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Almadani AK, Ahmed W, Al Obaidli AAK, Holt SG. Gender, age and nationality differences in chronic kidney disease prevalence in the emirate of Abu Dhabi, UAE. Nephrology (Carlton) 2024; 29:288-296. [PMID: 38450898 DOI: 10.1111/nep.14285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 02/19/2024] [Accepted: 02/21/2024] [Indexed: 03/08/2024]
Abstract
AIM We aimed to better understand the prevalence of chronic kidney disease in Abu Dhabi, UAE, where a very diverse ethnic population lives, each with their own risk profile. METHODS Data were analysed on all patients who were tested for serum creatinine in December 2019 for 4 years within our healthcare network. We analysed data for kidney disease by age, gender and nationality to study differences in prevalence and risk. RESULTS The entire cohort (EC) consisted 1 925 672 samples from 703 122 patients. 24% of patients had GFR < 90 mL/min/1.73 m2 (CKD2-5), 4% had more severe kidney dysfunction (CKD3-5) and 2% had UACR >3 mg/mmol and with GFR > 90 (CKD1). The long follow-up (LFU) group comprised 45.6% of patients who had eGFR on at least two occasions more than 90 days apart, and of these 19.5% had sustained eGFR <90, and 5.2% had CKD3-5. Males had lower eGFR than females in the EC (RR 1.68) and the LFU group (RR 1.76). Emirati Females had the lowest prevalence in the EC (2.9%) and expatriate females in the LFU (3.5%) groups. The relative risks of CKD in expatriate males were highest in the EC (2.14) and the LFU (2.39) groups. When we looked at the age distribution by nationality there were highly significant differences in some populations being highly represented at younger ages. CONCLUSION The prevalence of kidney disease in Abu Dhabi has a male predominance, with younger expatriates highly represented. A targeted strategy to identify those at high risk may identify early CKD to prevent progression to end-stage kidney disease.
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Affiliation(s)
- Ayman Kamal Almadani
- SEHA Kidney Care, Abu Dhabi, United Arab Emirates
- College of Medicine and Health Sciences, Khalifa University, Abu Dhabi, United Arab Emirates
| | - Wasim Ahmed
- SEHA Kidney Care, Abu Dhabi, United Arab Emirates
- College of Medicine and Health Sciences, Khalifa University, Abu Dhabi, United Arab Emirates
| | - Ali Abdul Kareem Al Obaidli
- SEHA Kidney Care, Abu Dhabi, United Arab Emirates
- College of Medicine and Health Sciences, Khalifa University, Abu Dhabi, United Arab Emirates
| | - Stephen G Holt
- SEHA Kidney Care, Abu Dhabi, United Arab Emirates
- College of Medicine and Health Sciences, Khalifa University, Abu Dhabi, United Arab Emirates
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Chacar S, Abdi A, Almansoori K, Alshamsi J, Al Hageh C, Zalloua P, Khraibi AA, Holt SG, Nader M. Role of CaMKII in diabetes induced vascular injury and its interaction with anti-diabetes therapy. Rev Endocr Metab Disord 2024; 25:369-382. [PMID: 38064002 PMCID: PMC10943158 DOI: 10.1007/s11154-023-09855-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/16/2023] [Indexed: 03/16/2024]
Abstract
Diabetes mellitus is a metabolic disorder denoted by chronic hyperglycemia that drives maladaptive structural changes and functional damage to the vasculature. Attenuation of this pathological remodeling of blood vessels remains an unmet target owing to paucity of information on the metabolic signatures of this process. Ca2+/calmodulin-dependent kinase II (CaMKII) is expressed in the vasculature and is implicated in the control of blood vessels homeostasis. Recently, CaMKII has attracted a special attention in view of its chronic upregulated activity in diabetic tissues, yet its role in the diabetic vasculature remains under investigation.This review highlights the physiological and pathological actions of CaMKII in the diabetic vasculature, with focus on the control of the dialogue between endothelial (EC) and vascular smooth muscle cells (VSMC). Activation of CaMKII enhances EC and VSMC proliferation and migration, and increases the production of extracellular matrix which leads to maladaptive remodeling of vessels. This is manifested by activation of genes/proteins implicated in the control of the cell cycle, cytoskeleton organization, proliferation, migration, and inflammation. Endothelial dysfunction is paralleled by impaired nitric oxide signaling, which is also influenced by CaMKII signaling (activation/oxidation). The efficiency of CaMKII inhibitors is currently being tested in animal models, with a focus on the genetic pathways involved in the regulation of CaMKII expression (microRNAs and single nucleotide polymorphisms). Interestingly, studies highlight an interaction between the anti-diabetic drugs and CaMKII expression/activity which requires further investigation. Together, the studies reviewed herein may guide pharmacological approaches to improve health-related outcomes in patients with diabetes.
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Affiliation(s)
- Stephanie Chacar
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates.
- Center for Biotechnology, Khalifa University of Science and Technology, 127788, Abu Dhabi, United Arab Emirates.
| | - Abdulhamid Abdi
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
| | - Khalifa Almansoori
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
| | - Jawaher Alshamsi
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
| | - Cynthia Al Hageh
- Department of Molecular Biology and Genetics, College of Medicine and Health Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
| | - Pierre Zalloua
- Department of Molecular Biology and Genetics, College of Medicine and Health Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
- Center for Biotechnology, Khalifa University of Science and Technology, 127788, Abu Dhabi, United Arab Emirates
| | - Ali A Khraibi
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
- Center for Biotechnology, Khalifa University of Science and Technology, 127788, Abu Dhabi, United Arab Emirates
| | - Stephen G Holt
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
- SEHA Kidney Care, SEHA, Abu Dhabi, UAE
| | - Moni Nader
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates.
- Center for Biotechnology, Khalifa University of Science and Technology, 127788, Abu Dhabi, United Arab Emirates.
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Al-Ani FM, Khandoker AH, Corridon PR, Holt SG. A novel model for predicting hospitalization risk among hemodialysis patients based on blood test variables. Annu Int Conf IEEE Eng Med Biol Soc 2023; 2023:1-4. [PMID: 38083570 DOI: 10.1109/embc40787.2023.10340227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2023]
Abstract
Hemodialysis patients are at high risk of hospitalization. Predicting such risk in dialysis patients may be critical to maintaining quality of life and reducing costs to the healthcare system. In this paper, we present and fractional polynomial stepwise logistic regression model to specify how routinely collected blood test variables could be linked to a significant increase in hospitalization risk. We found that eight of nineteen variables were significantly able to predict hospitalization risk; albumin (p<0.05), creatinine (p<0.05), calcium (p<0.01), bicarbonate (p<0.01), hemoglobin (p<0.05), mean cell hemoglobin concentration (MCHC) (p<0.0001), mean corpuscular volume (MCV) (p<0.0001), and potassium (p<0.01). The model achieved accuracy, sensitivity, and specificity of 77.31%, 83.03%, and 69.05%, respectively.
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Smith ER, Champion de Crespigny PJ, Vally F, Hewitson TD, Toussaint ND, Cade TJ, Holt SG. Cord blood effectively resists mineralization through mechanisms that stabilize calciprotein particles. Kidney Int 2023; 103:782-786. [PMID: 36516910 DOI: 10.1016/j.kint.2022.11.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 11/13/2022] [Accepted: 11/23/2022] [Indexed: 12/14/2022]
Affiliation(s)
- Edward R Smith
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia; Department of Medicine, University of Melbourne, Parkville, Melbourne, Victoria, Australia.
| | - Paul J Champion de Crespigny
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia; Department of Medicine, University of Melbourne, Parkville, Melbourne, Victoria, Australia; Department of Obstetrics and Gynaecology, The Royal Women's Hospital, Parkville, Melbourne, Victoria, Australia
| | - Fatima Vally
- Department of Obstetrics and Gynaecology, The Royal Women's Hospital, Parkville, Melbourne, Victoria, Australia
| | - Tim D Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia; Department of Medicine, University of Melbourne, Parkville, Melbourne, Victoria, Australia
| | - Nigel D Toussaint
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia; Department of Medicine, University of Melbourne, Parkville, Melbourne, Victoria, Australia
| | - Thomas J Cade
- Department of Obstetrics and Gynaecology, The Royal Women's Hospital, Parkville, Melbourne, Victoria, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia; Department of Medicine, University of Melbourne, Parkville, Melbourne, Victoria, Australia
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Thiem U, Hewitson TD, Toussaint ND, Holt SG, Haller MC, Pasch A, Cejka D, Smith ER. Effect of the phosphate binder sucroferric oxyhydroxide in dialysis patients on endogenous calciprotein particles, inflammation, and vascular cells. Nephrol Dial Transplant 2022; 38:1282-1296. [PMID: 36107466 PMCID: PMC10157755 DOI: 10.1093/ndt/gfac271] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Indexed: 11/14/2022] Open
Abstract
Abstract
Background
Calciprotein particles (CPP), colloidal mineral-protein nanoparticles, have emerged as potential mediators of phosphate toxicity in dialysis patients, with putative links to vascular calcification, endothelial dysfunction, and inflammation. We hypothesized that phosphate binder therapy with sucroferric oxyhydroxide (SO) would reduce endogenous CPP levels, and attenuate pro-calcific and pro-inflammatory effects of patient serum towards human vascular cells in vitro.
Methods
This secondary analysis of a randomized, controlled cross-over study compared the effect of two-week phosphate binder washout with high-dose (2000 mg/d) and low-dose (250 mg/d) SO therapy in 28 hemodialysis patients on serum CPP levels, inflammatory cytokine/chemokine arrays, and human aortic smooth muscle cell (HASMC) and coronary artery endothelial cell (HCAEC) bioassays.
Results
In our cohort (75% male, 62 ± 12 years) high-dose SO reduced primary (amorphous) and secondary (crystalline) CPP levels [-62 (-76 to -44)%, P < 0.0001 and -38 (-62 to -0.14)%, P < 0.001, respectively] compared with washout. Nine of 14 plasma cytokines/chemokines significantly decreased with high-dose SO, with consistent reductions in Interleukin-6 (IL-6) and IL-8. Exposure of HASMC and HCAEC cultures to serum of SO-treated patients reduced calcification and markers of activation (IL-6, IL-8, and vascular cell adhesion protein 1) compared with washout. Serum-induced HASMC calcification and HCAEC activation was ameliorated by removal of the CPP-containing fraction from patient sera. Effects of CPP removal were confirmed in an independent cohort of chronic kidney disease patients.
Conclusions
High-dose SO reduced endogenous CPP formation in dialysis patients and yielded serum with attenuated pro-calcific and inflammatory effects in vitro.
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Affiliation(s)
- Ursula Thiem
- Dept. of Medicine III - Nephrology, Hypertension, Transplantation Medicine, Rheumatology, Geriatrics, Ordensklinikum Linz - Elisabethinen Hospital , Linz , Austria
- Johannes Kepler University Linz, Medical Faculty , Linz , Austria
| | - Tim D Hewitson
- Dept. of Nephrology, The Royal Melbourne Hospital , Parkville, Victoria , Australia
- Dept. of Medicine (RMH), The University of Melbourne , Parkville, Victoria , Australia
| | - Nigel D Toussaint
- Dept. of Nephrology, The Royal Melbourne Hospital , Parkville, Victoria , Australia
- Dept. of Medicine (RMH), The University of Melbourne , Parkville, Victoria , Australia
| | - Stephen G Holt
- Dept. of Medicine (RMH), The University of Melbourne , Parkville, Victoria , Australia
| | - Maria C Haller
- Dept. of Medicine III - Nephrology, Hypertension, Transplantation Medicine, Rheumatology, Geriatrics, Ordensklinikum Linz - Elisabethinen Hospital , Linz , Austria
- CeMSIIS - Center for Medical Statistics, Informatics, and Intelligent Systems, Medical University Vienna , Vienna , Austria
| | - Andreas Pasch
- Calciscon AG , Nidau , Switzerland
- Lindenhofspital Bern , Bern , Switzerland
- Dept. of Physiology and Pathophysiology, Johannes Kepler University Linz , Linz , Austria
| | - Daniel Cejka
- Dept. of Medicine III - Nephrology, Hypertension, Transplantation Medicine, Rheumatology, Geriatrics, Ordensklinikum Linz - Elisabethinen Hospital , Linz , Austria
| | - Edward R Smith
- Dept. of Nephrology, The Royal Melbourne Hospital , Parkville, Victoria , Australia
- Dept. of Medicine (RMH), The University of Melbourne , Parkville, Victoria , Australia
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Bruell S, Nicholls KM, Hewitson TD, Talbot AS, Holt SG, Smith ER, Ruderman I. Reduced hip bone mineral density is associated with high levels of calciprotein particles in patients with Fabry disease. Osteoporos Int 2022; 33:1783-1794. [PMID: 35575807 PMCID: PMC9499881 DOI: 10.1007/s00198-022-06420-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Accepted: 05/03/2022] [Indexed: 12/01/2022]
Abstract
UNLABELLED Calciprotein particles (CPP) are nanoscale mineralo-protein aggregates that help stabilize excess mineral in the circulation. We examined the relationship between CPP and bone mineral density in Fabry disease patients. We found an inverse correlation with total hip and femoral neck density, but none with lumbar spine. PURPOSE Calciprotein particles (CPP) are colloidal mineral-protein complexes made up primarily of the circulating glycoprotein fetuin-A, calcium, and phosphate. They form in extracellular fluid and facilitate the stabilization, transport, and clearance of excess minerals from the circulation. While most are monomers, they also exist in larger primary (CPP-I) and secondary (CPP-II) form, both of which are reported to be raised in pathological states. This study sought to investigate CPP levels in the serum of patients with Fabry disease, an X-linked systemic lysosomal storage disorder that is associated with generalized inflammation and low bone mineral density (BMD). METHODS We compared serum CPP-I and CPP-II levels in 59 patients with Fabry disease (37 female) with levels in an age-matched healthy adult cohort (n=28) and evaluated their association with BMD and biochemical data obtained from routine clinical review. RESULTS CPP-I and CPP-II levels were higher in male Fabry disease patients than female sufferers as well as their corresponding sex- and age-matched controls. CPP-II levels were inversely correlated with BMD at the total hip and femoral neck, but not the lumbar spine. Regression analyses revealed that these associations were independent of common determinants of BMD, but at the femoral neck, a significant association was only found in female patients. CONCLUSION Low hip BMD was associated with high CPP-II in patients with Fabry disease, but further work is needed to investigate the relevance of sex-related differences and to establish whether CPP measurement may aid assessment of bone disease in this setting.
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Affiliation(s)
- S Bruell
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia
| | - K M Nicholls
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia
- Department of Medicine (RMH), University of Melbourne, Parkville, Australia
| | - T D Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia
- Department of Medicine (RMH), University of Melbourne, Parkville, Australia
| | - A S Talbot
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia
| | - S G Holt
- Department of Medicine (RMH), University of Melbourne, Parkville, Australia
- SEHA Kidney Care, Abu Dhabi Health Services Company, Abu Dhabi, United Arab Emirates
- Khalifa University, Abu Dhabi, United Arab Emirates
| | - E R Smith
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia.
- Department of Medicine (RMH), University of Melbourne, Parkville, Australia.
- Kincaid-Smith Renal Laboratories, Department of Nephrology, The Royal Melbourne Hospital, Grattan Street, Parkville, Victoria, 3052, Australia.
| | - I Ruderman
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia
- Department of Medicine (RMH), University of Melbourne, Parkville, Australia
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Madam AA, Ahmed W, Al Obaidli AAK, Smith ER, Holt SG. Coronavirus Disease 2019 Infection and ABO Blood Groups in a Hemodialysis Cohort in the United Arab Emirates. Saudi J Kidney Dis Transpl 2022; 33:413-417. [PMID: 37843142 DOI: 10.4103/1319-2442.385964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2023] Open
Abstract
Some epidemiological data have implicated blood groups in susceptibility to coronavirus disease 2019 (COVID-19) infection. We were interested to see if there was any apparent effect of different ABO blood groups on susceptibility to COVID-19 infection in unvaccinated hemodialysis (HD) patients, as they had a high rate of mortality from this infection. Blood group O has been suggested to be protective against COVID-19 infection; however, since the ABO frequency is affected by ethnicity, we looked at infection frequency and blood group and corrected the expected frequency for the ethnicity of our cohort. We examined 249 HD patients presenting with a positive COVID-19 polymerase chain reaction regarding their ABO blood group and compared the ABO frequencies with published data for the United Arab Emirates (UAE), as well as international and historical ABO data on dialysis frequency. Although there was an apparent protective effect of blood group O when we compared blood group frequencies with the UAE data, this disappeared when corrected for ethnicity. We concluded that any association of the ABO blood group with COVID-19 infection is unlikely to be of major importance and should not be used to reassure patients that they are mildly protected against COVID-19 without vaccination.
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Affiliation(s)
- Ayman Al Madam
- SEHA Kidney Care, Central Unit, Abu Dhabi, United Arab Emirates
| | - Wasim Ahmed
- SEHA Kidney Care, Central Unit, Abu Dhabi, United Arab Emirates
| | | | | | - Stephen G Holt
- SEHA Kidney Care, Central Unit, Abu Dhabi, United Arab Emirates; University of Melbourne, Melbourne, Victoria, Australia
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Tiong MK, Smith ER, Pascoe EM, Elder GJ, Lioufas NM, Pedagogos E, Hawley CM, Valks A, Holt SG, Hewitson TD, Toussaint ND. Effect of lanthanum carbonate on serum calciprotein particles in patients with stage 3-4 CKD-results from a placebo-controlled randomized trial. Nephrol Dial Transplant 2022; 38:344-351. [PMID: 35212735 PMCID: PMC9923701 DOI: 10.1093/ndt/gfac043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Calciprotein particles (CPP) are colloidal aggregates of calcium phosphate and the mineral-binding protein fetuin-A, and are potential mediators of cardiovascular disease in chronic kidney disease (CKD). Emerging evidence suggests non-calcium-containing phosphate binders may reduce serum CPP in patients with kidney failure who require dialysis; however, it is unclear whether similar interventions are effective in patients with earlier stages of CKD. METHODS The IMpact of Phosphate Reduction On Vascular End-points in CKD (IMPROVE-CKD) was a multi-centre, placebo-controlled, randomized trial of lanthanum carbonate on cardiovascular markers in 278 participants with stage 3b/4 CKD. In this pre-specified exploratory analysis, primary (CPP-I) and secondary CPP (CPP-II) were measured in a sub-cohort of participants over 96 weeks. Treatment groups were compared using linear mixed-effects models and the relationship between serum CPP and pulse wave velocity (PWV) and abdominal aortic calcification (AAC) was examined. RESULTS A total of 253 participants had CPP data for baseline and at least one follow-up timepoint and were included in this analysis. The mean age was 62.4 ± 12.6 years, 32.0% were female and the mean estimated glomerular filtration rate (eGFR) was 26.6 ± 8.3 mL/min/1.73 m2. Baseline median serum CPP-I was 14.9 × 104 particles/mL [interquartile range (IQR) 4.6-49.3] and median CPP-II was 3.3 × 103 particles/mL (IQR 1.4-5.4). There was no significant difference between treatment groups at 96 weeks in CPP-I [22.8% (95% confidence interval -39.2, 36.4), P = 0.65] or CPP-II [-18.3% (95% confidence interval -40.0, 11.2), P = 0.20] compared with a placebo. Serum CPP were not correlated with baseline PWV or AAC, or with the progression of either marker. CONCLUSIONS Lanthanum carbonate was not associated with a reduction of CPP at 96 weeks when compared with a placebo in a CKD cohort.
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Affiliation(s)
| | - Edward R Smith
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia,Department of Medicine (RMH), University of Melbourne, Parkville, Australia
| | - Elaine M Pascoe
- Australasian Kidney Trials Network, The University of Queensland, Brisbane, Australia
| | - Grahame J Elder
- University of Notre Dame, Sydney, Australia,University of Sydney, Sydney, Australia,Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, Darlinghurst, Australia,Department of Nephrology, Westmead Hospital, Sydney, Australia
| | - Nicole M Lioufas
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia,Department of Medicine (RMH), University of Melbourne, Parkville, Australia,Department of Nephrology, Western Health, Sunshine, Australia
| | | | - Carmel M Hawley
- Australasian Kidney Trials Network, The University of Queensland, Brisbane, Australia,Department of Nephrology, Princess Alexandra Hospital, Brisbane, Australia,Translational Research Institute, Brisbane, Queensland, Australia
| | - Andrea Valks
- Australasian Kidney Trials Network, The University of Queensland, Brisbane, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia,Department of Medicine (RMH), University of Melbourne, Parkville, Australia,SEHA Kidney Care, Abu Dhabi Health Services Company, Abu Dhabi, United Arab Emirates,Khalifa University, Abu Dhabi, United Arab Emirates
| | - Tim D Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia,Department of Medicine (RMH), University of Melbourne, Parkville, Australia
| | - Nigel D Toussaint
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia,Department of Medicine (RMH), University of Melbourne, Parkville, Australia
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Tiong MK, Holt SG, Ford ML, Smith ER. Serum Calciprotein Monomers and Chronic Kidney Disease Progression. Am J Nephrol 2022; 53:806-815. [PMID: 36473431 DOI: 10.1159/000526609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 08/12/2022] [Indexed: 12/12/2022]
Abstract
INTRODUCTION Elevated levels of fibroblast growth factor-23 (FGF23) in chronic kidney disease (CKD) are associated with progression of CKD. FGF23 inhibits proximal tubular phosphate reabsorption, raising phosphate concentrations in the tubular fluid of functioning nephrons, predisposing to spontaneous precipitation of calcium phosphate crystals and resultant tubular injury. Calciprotein monomers (CPM) form spontaneously in biological fluids when clusters of calcium phosphate ions are bound by the liver-derived glycoprotein fetuin-A. Serum CPM are elevated in CKD and are postulated to trigger FGF23 secretion. CPM are also readily filtered at the glomerulus into the tubular fluid, suggesting that higher CPM levels could be associated with progression of CKD via FGF23-mediated increased phosphate load but also through direct effects in the proximal tubule. METHODS ACADEMIC was a prospective observational study of 200 stable outpatients with CKD stages 3 and 4. Participants were followed until commencement of dialysis or death. In this study, we examined a sub-cohort of 189 participants who had baseline serum available for measurement of CPM. Cox proportionate hazard regression models were used to examine the association between CPM and a composite kidney disease outcome (commencement of dialysis or reduction in estimated glomerular filtration rate [eGFR] >30%). Linear regression models were used to examine the association between CPM and annualized eGFR slope. RESULTS Relative to the lowest tertile, the highest tertile of CPM was associated with increased risk of the composite kidney disease outcome in univariate models and after sequential adjustment for conventional risk factors for progression of CKD (adjusted hazard ratio 4.22; 95% confidence interval [CI] 1.91, 9.33, p < 0.001). Natural log-transformed CPM was also inversely associated with eGFR slope in univariate and multivariate adjusted models (adjusted β-coefficient -1.66, 95% CI: -3.10, -0.22, p = 0.024). In exploratory mediation analysis, the association between serum CPM and eGFR slope was partially mediated by iFGF23; however, the majority of the association was direct and independent of the iFGF23 pathway. CONCLUSION Elevated levels of CPM are associated with the progression of CKD. This association was partially mediated via FGF23, consistent with recent evidence that FGF23 predisposes to spontaneous precipitation of calcium phosphate crystals leading to tubular injury. However, serum CPM also appeared to have a direct association with eGFR slope, raising the possibility that CPM may also be associated with progression of CKD through additional pathways.
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Affiliation(s)
- Mark K Tiong
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Victoria, Australia.,Department of Medicine (RMH), University of Melbourne, Parkville, Victoria, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Victoria, Australia.,Department of Medicine (RMH), University of Melbourne, Parkville, Victoria, Australia.,SEHA Kidney Care, Abu Dhabi Health Services Company, Abu Dhabi, United Arab Emirates.,Department of Medicine, Khalifa University, Abu Dhabi, United Arab Emirates
| | - Martin L Ford
- Department of Renal Medicine, King's College Hospital NHS Foundation Trust, London, UK.,Faculty of Life Sciences & Medicine, Kings College London, London, UK
| | - Edward R Smith
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Victoria, Australia.,Department of Medicine (RMH), University of Melbourne, Parkville, Victoria, Australia
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Toussaint ND, Damasiewicz MJ, Holt SG, Lu ZX, Magliano DJ, Atkins RC, Chadban SJ, Shaw JE, Polkinghorne KR. Relationship Between Urinary Phosphate and All-Cause and Cardiovascular Mortality in a National Population-Based Longitudinal Cohort Study. J Ren Nutr 2021; 32:510-519. [DOI: 10.1053/j.jrn.2021.10.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 09/29/2021] [Accepted: 10/18/2021] [Indexed: 01/06/2023] Open
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Sypek MP, Kausman JY, Watson N, Wyburn K, Holt SG, Hughes P, Clayton PA. The Introduction of cPRA and Its Impact on Access to Deceased Donor Kidney Transplantation for Highly Sensitized Patients in Australia. Transplantation 2021; 105:1317-1325. [PMID: 34019363 DOI: 10.1097/tp.0000000000003410] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND In March 2016, Australia's deceased donor kidney allocation program introduced calculated panel reactive antibody (cPRA) based on antibody exclusions using multiplex assays to define sensitization for waitlisted candidates. We aimed to assess the impact of this change and review access to transplantation for highly sensitized patients under the current allocation rules. METHODS Registry data were used to reconstruct changes in panel reactive antibody (PRA)/cPRA for all patients active on the waiting list between 2013 and 2018. A multilevel, mixed-effects negative binomial regression model was used to determine the association between sensitization and transplantation rate in the cPRA era. RESULTS Following the introduction of cPRA, there was an increase in the percentage of the waiting list classified as highly sensitized (PRA/cPRA ≥80%) from 7.2% to 27.8% and very highly sensitized (PRA/cPRA ≥99%) from 2.7% to 15.3%. Any degree of sensitization was associated with a decreased rate of transplantation with a marked reduction for those with cPRA 95%-98% (adjusted incidence rate ratio, 0.36 [95% confidence interval, 0.28-0.47], P < 0.001) and cPRA ≥99% (adjusted incidence rate ratio, 0.09 [95% confidence interval, 0.07-0.12], P < 0.001). CONCLUSIONS The proportion of the waiting list classified as highly sensitized increased substantially following the introduction of cPRA, and despite current prioritization, very highly sensitized patients have markedly reduced access to deceased donor transplantation.
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Affiliation(s)
- Matthew P Sypek
- Faculty of Medicine, Dentistry and Health Science, University of Melbourne, Melbourne, Australia
- Department of Nephrology, Royal Melbourne Hospital, Melbourne, Australia
- Department of Nephrology, Royal Children's Hospital, Melbourne, Australia
- Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry, South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Joshua Y Kausman
- Department of Nephrology, Royal Children's Hospital, Melbourne, Australia
- Clinical Paediatrics, Murdoch Children's Research Institute, Melbourne, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Narelle Watson
- Transplantation and Immunogenetics Services, Australian RedCross Lifeblood, Brisbane, Australia
| | - Kate Wyburn
- Royal Prince Alfred Hospital and Sydney Medical School, Faculty of Medicine and Health, University of Sydney, Sydney, Australia
| | - Stephen G Holt
- Faculty of Medicine, Dentistry and Health Science, University of Melbourne, Melbourne, Australia
- Department of Nephrology, Royal Melbourne Hospital, Melbourne, Australia
| | - Peter Hughes
- Faculty of Medicine, Dentistry and Health Science, University of Melbourne, Melbourne, Australia
- Department of Nephrology, Royal Melbourne Hospital, Melbourne, Australia
| | - Philip A Clayton
- Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry, South Australian Health and Medical Research Institute, Adelaide, Australia
- Adelaide Medical School, University of Adelaide, Adelaide, Australia
- Central and Northern Renal and Transplantation Service, Royal Adelaide Hospital, Adelaide, Australia
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12
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Tiong MK, Smith ER, Toussaint ND, Al-Khayyat HF, Holt SG. Reduction of Calciprotein Particles in Adults Receiving Infliximab for Chronic Inflammatory Disease. JBMR Plus 2021; 5:e10497. [PMID: 34189386 PMCID: PMC8216135 DOI: 10.1002/jbm4.10497] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Accepted: 03/22/2021] [Indexed: 01/13/2023] Open
Abstract
Patients with chronic inflammatory diseases (CID) experience accelerated loss of bone mineral density, which is often accompanied by increased vascular calcification. These disturbances can be attenuated by therapies for inflammation, such as the tumor necrosis factor inhibitor infliximab. Calciprotein particles (CPP) are circulating colloidal aggregates of calcium and phosphate together with the mineral-binding protein fetuin-A, which have emerged as potential mediators of vascular calcification. The precise origins of serum CPP are unclear, but bone turnover may be an important source. In this longitudinal observational study, we studied patients with CID undergoing treatment with infliximab to assess the temporal relationship between bone turnover and circulating CPP. Ten patients with active CID receiving infliximab induction therapy and an additional 3 patients with quiescent CID on maintenance infliximab therapy were studied for 8 weeks with repeated measures of bone turnover markers as well as CPP (calciprotein monomers [CPM], primary CPP [CPP-I], and secondary CPP [CPP-II]). Therapeutic response was appraised using validated disease activity scores. At baseline, those with active CID had elevated markers of bone resorption and suppressed bone formation markers as well as higher CPM and CPP-I compared with those with quiescent CID. In responders, there was an early but transient reduction in resorption markers by week 1, but a more sustained increase in bone formation markers compared with non-responders at week 8. This was accompanied by reductions in CPM (β = -6.5 × 103 AU [95% CI -11.1, -1.8], p = 0.006) and CPP-I (β = -23.4 × 104 particles/mL [95% CI -34.8, -11.9], p < 0.001). In contrast, no significant changes in any markers were observed in non-responders or those receiving maintenance therapy. Thus, CPP have a dynamic association with changes in bone turnover in response to infliximab therapy, adding to accumulating evidence of the role of bone as a determinant of systemic levels. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Mark K Tiong
- Department of Nephrology The Royal Melbourne Hospital Parkville Australia.,Department of Medicine (RMH) University of Melbourne Parkville Australia
| | - Edward R Smith
- Department of Nephrology The Royal Melbourne Hospital Parkville Australia.,Department of Medicine (RMH) University of Melbourne Parkville Australia
| | - Nigel D Toussaint
- Department of Nephrology The Royal Melbourne Hospital Parkville Australia.,Department of Medicine (RMH) University of Melbourne Parkville Australia
| | - Hasan F Al-Khayyat
- Department of Nephrology The Royal Melbourne Hospital Parkville Australia
| | - Stephen G Holt
- Department of Nephrology The Royal Melbourne Hospital Parkville Australia.,Department of Medicine (RMH) University of Melbourne Parkville Australia.,SEHA Kidney Care Abu Dhabi Health Services Company Abu Dhabi United Arab Emirates.,Khalifa University Abu Dhabi United Arab Emirates
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13
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Thwaites SE, Holt SG, Yii MK. Inferiority of arteriovenous grafts, in comparison to autogenous fistulas, is underestimated by standard survival measures alone. ANZ J Surg 2020; 91:162-167. [PMID: 33295103 DOI: 10.1111/ans.16472] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 09/27/2020] [Accepted: 10/30/2020] [Indexed: 12/19/2022]
Abstract
BACKGROUND It has been argued that a prosthetic arteriovenous graft (AVG) is a reasonable alternative to an arteriovenous fistula (AVF) for dialysis. We aimed to compare the patency rates and requirements for the intervention of newly formed AVF and AVG. METHODS A retrospective analysis was undertaken of AVF and AVG formed between 1 January 2013 and 31 December 2015 at two tertiary referral centres and followed up until 31 December 2017. Outcome measures included successful use for dialysis, patency rates and the number of interventions required to maintain dialysis access per patient-year (PPY). RESULTS Four hundred and seventy AVF and 92 AVG were constructed. Of 470 AVF, 324 (68.9%) were used compared to 80 of 92 (87%) AVG. One year assisted primary patency of AVF was 75% (confidence interval 71-79%) compared to 47% (confidence interval 36-57%) for AVG. Secondary patency rates for AVF at 1, 2 and 3 years were 77%, 71% and 69%, respectively. At the same time points, secondary patency rates for AVG were 77%, 60% and 46%, respectively (log rank P = 0.034). AVG required 2.4 times the number of interventions PPY than AVF. Surgical thrombectomy of AVG was at a rate of 0.49 PPY compared with 0.042 PPY for AVF. CONCLUSION AVG have a substantially higher rate of thrombosis than AVF, evident from early in the life of the graft. AVF demonstrate superior patency rates to AVG throughout the life of the access, with far fewer interventions PPY than grafts.
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Affiliation(s)
- Stephen E Thwaites
- Department of Surgery, Monash Medical Centre, Melbourne, Victoria, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Victoria, Australia
| | - Ming K Yii
- Department of Surgery, Monash Medical Centre, Melbourne, Victoria, Australia.,Department of Surgery, School of Clinical Sciences at Monash Health, Monash University, Melbourne, Victoria, Australia
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14
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Holt SG, Locarnini S, Sasadeusz J. Hepatitis B related dilemmas in the renal unit. Nephrology (Carlton) 2020; 26:287-293. [PMID: 33155307 DOI: 10.1111/nep.13815] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 09/07/2020] [Accepted: 11/01/2020] [Indexed: 12/19/2022]
Abstract
Testing for hepatitis B in dialysis patients is routine, but newer and more sensitive detection methods mean that there is sometimes confusion around viral loads and occult infection. There are frequently difficult choices surrounding isolation and treatment. Here we describe the use of HBV serology and DNA testing in decisions around patients with end-stage renal disease. We also suggest isolation decisions based on our current understanding of the virus and its infectivity.
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Affiliation(s)
- Stephen G Holt
- Department of Medicine, Dentistry and Health Science, The University of Melbourne, Melbourne, Victoria, Australia.,Abu Dhabi Health Services Company (SEHA) Kidney Care, Abu Dhabi, UAE
| | - Stephen Locarnini
- Research and Molecular Development, Peter Doherty Institute of Infection and Immunity, Melbourne, Victoria, Australia.,Victorian Infectious Diseases Reference Laboratory, Peter Doherty Institute of Infection and Immunity, Melbourne, Victoria, Australia
| | - Joe Sasadeusz
- Abu Dhabi Health Services Company (SEHA) Kidney Care, Abu Dhabi, UAE.,Research and Molecular Development, Peter Doherty Institute of Infection and Immunity, Melbourne, Victoria, Australia.,Victorian Infectious Diseases Service, Royal Melbourne Hospital, Melbourne, Victoria, Australia
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15
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Toussaint ND, Pedagogos E, Lioufas NM, Elder GJ, Pascoe EM, Badve SV, Valks A, Block GA, Boudville N, Cameron JD, Campbell KL, Chen SSM, Faull RJ, Holt SG, Jackson D, Jardine MJ, Johnson DW, Kerr PG, Lau KK, Hooi LS, Narayan O, Perkovic V, Polkinghorne KR, Pollock CA, Reidlinger D, Robison L, Smith ER, Walker RJ, Wang AYM, Hawley CM. A Randomized Trial on the Effect of Phosphate Reduction on Vascular End Points in CKD (IMPROVE-CKD). J Am Soc Nephrol 2020; 31:2653-2666. [PMID: 32917784 PMCID: PMC7608977 DOI: 10.1681/asn.2020040411] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2020] [Accepted: 07/14/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Hyperphosphatemia is associated with increased fibroblast growth factor 23 (FGF23), arterial calcification, and cardiovascular mortality. Effects of phosphate-lowering medication on vascular calcification and arterial stiffness in CKD remain uncertain. METHODS To assess the effects of non-calcium-based phosphate binders on intermediate cardiovascular markers, we conducted a multicenter, double-blind trial, randomizing 278 participants with stage 3b or 4 CKD and serum phosphate >1.00 mmol/L (3.10 mg/dl) to 500 mg lanthanum carbonate or matched placebo thrice daily for 96 weeks. We analyzed the primary outcome, carotid-femoral pulse wave velocity, using a linear mixed effects model for repeated measures. Secondary outcomes included abdominal aortic calcification and serum and urine markers of mineral metabolism. RESULTS A total of 138 participants received lanthanum and 140 received placebo (mean age 63.1 years; 69% male, 64% White). Mean eGFR was 26.6 ml/min per 1.73 m2; 45% of participants had diabetes and 32% had cardiovascular disease. Mean serum phosphate was 1.25 mmol/L (3.87 mg/dl), mean pulse wave velocity was 10.8 m/s, and 81.3% had abdominal aortic calcification at baseline. At 96 weeks, pulse wave velocity did not differ significantly between groups, nor did abdominal aortic calcification, serum phosphate, parathyroid hormone, FGF23, and 24-hour urinary phosphate. Serious adverse events occurred in 63 (46%) participants prescribed lanthanum and 66 (47%) prescribed placebo. Although recruitment to target was not achieved, additional analysis suggested this was unlikely to have significantly affected the principle findings. CONCLUSIONS In patients with stage 3b/4 CKD, treatment with lanthanum over 96 weeks did not affect arterial stiffness or aortic calcification compared with placebo. These findings do not support the role of intestinal phosphate binders to reduce cardiovascular risk in patients with CKD who have normophosphatemia. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER Australian Clinical Trials Registry, ACTRN12610000650099.
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Affiliation(s)
- Nigel D Toussaint
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Victoria, Australia
- Department of Medicine, The Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia
| | - Eugenia Pedagogos
- Department of Medicine, The Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia
- Alfred Health, Melbourne, Victoria, Australia
- Western Health, Melbourne, Victoria, Australia
| | - Nicole M Lioufas
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Victoria, Australia
- Department of Medicine, The Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia
- Western Health, Melbourne, Victoria, Australia
| | - Grahame J Elder
- School of Medicine, University of Notre Dame, Sydney, New South Wales, Australia
- Faculty of Medicine and Health, University of Sydney, Sydney, New South Wales, Australia
- Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Elaine M Pascoe
- Australasian Kidney Trials Network, The University of Queensland, Brisbane, Queensland, Australia
| | - Sunil V Badve
- St. George Hospital, Sydney, New South Wales, Australia
- Renal and Metabolic Division, The George Institute for Global Health, University of New South Wales, Sydney, New South Wales, Australia
| | - Andrea Valks
- Australasian Kidney Trials Network, The University of Queensland, Brisbane, Queensland, Australia
| | | | - Neil Boudville
- Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
- Medical School, University of Western Australia, Perth, Western Australia, Australia
| | - James D Cameron
- Monash Cardiovascular Research Centre, Monash Heart, Monash Health, Clayton, Victoria, Australia
- Department of Medicine, Monash University, Clayton, Victoria, Australia
| | - Katrina L Campbell
- Department of Nephrology, Princess Alexandra Hospital, Brisbane, Queensland, Australia
| | | | - Randall J Faull
- Department of Medicine, University of Adelaide, Adelaide, South Australia, Australia
- Central Northern Adelaide Renal and Transplantation Services, Adelaide, South Australia, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Victoria, Australia
- Department of Medicine, The Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia
| | | | - Meg J Jardine
- Concord Repatriation and General Hospital, Concord, New South Wales, Australia
- The George Institute for Global Health, University of New South Wales, Sydney, New South Wales, Australia
| | - David W Johnson
- Australasian Kidney Trials Network, The University of Queensland, Brisbane, Queensland, Australia
- Department of Nephrology, Princess Alexandra Hospital, Brisbane, Queensland, Australia
- Translational Research Institute, Brisbane, Queensland, Australia
| | - Peter G Kerr
- Department of Medicine, Monash University, Clayton, Victoria, Australia
- Monash Health, Clayton, Victoria, Australia
| | - Kenneth K Lau
- Department of Medicine, Monash University, Clayton, Victoria, Australia
- Monash Health, Clayton, Victoria, Australia
| | | | - Om Narayan
- Monash Cardiovascular Research Centre, Monash Heart, Monash Health, Clayton, Victoria, Australia
- Department of Medicine, Monash University, Clayton, Victoria, Australia
| | - Vlado Perkovic
- Renal and Metabolic Division, The George Institute for Global Health, University of New South Wales, Sydney, New South Wales, Australia
| | - Kevan R Polkinghorne
- Department of Medicine, Monash University, Clayton, Victoria, Australia
- Monash Health, Clayton, Victoria, Australia
- Department of Epidemiology and Preventive Medicine, Monash University, Clayton, Victoria, Australia
| | - Carol A Pollock
- Kolling Institute, Royal North Shore Hospital, University of Sydney, Sydney, New South Wales, Australia
| | - Donna Reidlinger
- Australasian Kidney Trials Network, The University of Queensland, Brisbane, Queensland, Australia
| | - Laura Robison
- Australasian Kidney Trials Network, The University of Queensland, Brisbane, Queensland, Australia
| | - Edward R Smith
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Victoria, Australia
- Department of Medicine, The Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia
| | - Robert J Walker
- Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | | | - Carmel M Hawley
- Australasian Kidney Trials Network, The University of Queensland, Brisbane, Queensland, Australia
- Department of Nephrology, Princess Alexandra Hospital, Brisbane, Queensland, Australia
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16
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Flavell AL, Fullinfaw RO, Smith ER, Holt SG, Finlay MJ, Barbour TD. Noninfectious mixed cryoglobulinaemic glomerulonephritis and monoclonal gammopathy of undetermined significance: a coincidental association? BMC Nephrol 2020; 21:293. [PMID: 32703171 PMCID: PMC7376917 DOI: 10.1186/s12882-020-01941-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 07/09/2020] [Indexed: 12/18/2022] Open
Abstract
Background Cryoglobulins are cold-precipitable immunoglobulins that may cause systemic vasculitis including cryoglobulinaemic glomerulonephritis (CGN). Type 1 cryoglobulins consist of isolated monoclonal immunoglobulin (mIg), whereas mixed cryoglobulins are typically immune complexes comprising either monoclonal (type 2) or polyclonal (type 3) Ig with rheumatoid activity against polyclonal IgG. Only CGN related to type 1 cryoglobulins has been clearly associated with monoclonal gammopathy of undetermined significance (MGUS) using the conventional serum-, urine- or tissue-based methods of paraprotein detection. Case presentation We present four patients with noninfectious mixed (type 2 or 3) CGN and MGUS. Two patients had type 2 cryoglobulinaemia, one had type 3 cryoglobulinaemia, and one lacked definitive typing of the serum cryoprecipitate. The serum monoclonal band was IgM-κ in all four cases. Treatments included corticosteroids, cyclophosphamide, plasma exchange, and rituximab. At median 3.5 years’ follow-up, no patient had developed a haematological malignancy or advanced chronic kidney disease. Other potential causes of mixed cryoglobulinaemia were also present in our cohort, notably primary Sjögren’s syndrome in three cases. Conclusion Our study raises questions regarding the current designation of type 2 CGN as a monoclonal gammopathy of renal significance, and the role of clonally directed therapies for noninfectious mixed CGN outside the setting of haematological malignancy.
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Affiliation(s)
- Adam L Flavell
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia.
| | - Robert O Fullinfaw
- Department of Chemical Pathology, The Royal Melbourne Hospital, Parkville, Australia
| | - Edward R Smith
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia.,Department of Medicine, The University of Melbourne, Melbourne, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia.,Department of Medicine, The University of Melbourne, Melbourne, Australia
| | - Moira J Finlay
- Department of Medicine, The University of Melbourne, Melbourne, Australia.,Department of Anatomical Pathology, The Royal Melbourne Hospital, Parkville, Australia
| | - Thomas D Barbour
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia.,Department of Medicine, The University of Melbourne, Melbourne, Australia
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17
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Ruderman I, Hewitson TD, Smith ER, Holt SG, Wigg B, Toussaint ND. Vascular calcification in skin and subcutaneous tissue in patients with chronic and end-stage kidney disease. BMC Nephrol 2020; 21:279. [PMID: 32677907 PMCID: PMC7364566 DOI: 10.1186/s12882-020-01928-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 07/05/2020] [Indexed: 12/15/2022] Open
Abstract
Background Vascular calcification (VC) is well described in large- and medium-sized vessels in patients with chronic kidney disease (CKD), especially in those with end-stage kidney disease (ESKD) on dialysis. Medial calcification is particularly prevalent in this population and contributes to arterial stiffness and increased cardiovascular mortality and morbidity. Apart from in the setting of calciphylaxis, few studies have assessed skin and subcutaneous calcification and associations with abnormalities of bone and mineral metabolism in patients with CKD. Methods We performed a single-centre observational study to evaluate incisional skin tissue samples from three anatomical sites in patients with different stages of CKD undergoing elective surgery. We compared these samples to skin samples of a control cohort without CKD. Staining for calcification was performed with von Kossa method. A subgroup of skin samples were assessed by RT-PCR for upregulation of pro-calcific gene transcripts for tissue non-specific alkaline phosphatase (TNAP) and Runt-related transcription factor 2 (RUNX2). Results Forty-five patients were evaluated, 34 with CKD (including ESKD) and 11 control patients. VC was identified in 15 skin samples (13 CKD/ESKD and 2 controls). VC was present in the dermal and subcutaneous tissues of the neck, abdomen and arm samples. Two different histological types of VC were identified: speckled medial calcification and internal elastic lamina calcification. Presence of perieccrine calcification was identified in 14 samples, 10 with concurrent VC. There were no significant differences in serum parathyroid hormone, phosphate or calcium in patients with or without VC. Expression of TNAP or RUNX2 was not increased in samples from patients with ESKD or those with histological evidence of calcification. Conclusion This study reports the novel finding of dermal and subcutaneous calcification in multiple anatomical locations in 38% of patients with advanced CKD/ESKD undergoing elective surgery but free from calciphylaxis.
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Affiliation(s)
- Irene Ruderman
- Department of Nephrology, The Royal Melbourne Hospital, 300 Grattan St, Parkville, Victoria, 3050, Australia. .,Department of Medicine (RMH), The University of Melbourne, Parkville, Victoria, Australia.
| | - Tim D Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, 300 Grattan St, Parkville, Victoria, 3050, Australia.,Department of Medicine (RMH), The University of Melbourne, Parkville, Victoria, Australia
| | - Edward R Smith
- Department of Nephrology, The Royal Melbourne Hospital, 300 Grattan St, Parkville, Victoria, 3050, Australia.,Department of Medicine (RMH), The University of Melbourne, Parkville, Victoria, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, 300 Grattan St, Parkville, Victoria, 3050, Australia.,Department of Medicine (RMH), The University of Melbourne, Parkville, Victoria, Australia
| | - Belinda Wigg
- Department of Nephrology, The Royal Melbourne Hospital, 300 Grattan St, Parkville, Victoria, 3050, Australia
| | - Nigel D Toussaint
- Department of Nephrology, The Royal Melbourne Hospital, 300 Grattan St, Parkville, Victoria, 3050, Australia.,Department of Medicine (RMH), The University of Melbourne, Parkville, Victoria, Australia
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18
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Holt SG, Kotagiri P, Hogan C, Hughes P, Masterson R. The potential role of antibodies against minor blood group antigens in renal transplantation. Transpl Int 2020; 33:841-848. [PMID: 32619297 DOI: 10.1111/tri.13685] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 05/18/2020] [Accepted: 06/25/2020] [Indexed: 12/29/2022]
Abstract
Blood group antigens are red blood cell (RBC) surface markers comprising specific carbohydrate moieties attached to the glycolipids and glycoproteins within the membrane. In addition to the major ABO blood group antigens, at least 35 minor blood group antigens have been defined to date. These antigens have immunogenic potential and may cause a transfusion reaction. There is evidence for renal expression of antigens from the Kidd, MNS, Duffy and Lewis groups and therefore the potential for antibodies directed against these antigens to cross-react in a transplanted kidney. In individuals lacking a specific RBC antigen, antibodies may develop after de novo exposure to that antigen, in addition to the potential presence of pre-existing innate antibodies. Relatively little attention has been paid to non-ABO system antibodies, with most reports in the literature focusing on transfusion reactions rather than on any putative role in allograft rejection. Here, we review each of these antigens in the context of renal transplantation and what limited evidence there is on how such immunological risk may be assessed and managed.
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Affiliation(s)
- Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, VIC, Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, VIC, Australia
| | - Prasanti Kotagiri
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, VIC, Australia
| | - Chris Hogan
- Department of Haematology, The Royal Melbourne Hospital, Parkville, VIC, Australia.,Australian Redcross, Melbourne, VIC, Australia
| | - Peter Hughes
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, VIC, Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, VIC, Australia
| | - Rosemary Masterson
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, VIC, Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, VIC, Australia
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19
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Holt SG, Yo JH, Karschimkus C, Volpato F, Christov S, Smith ER, Hewitson TD, Worth LJ, Champion De Crespigny P. Monitoring skin temperature at the wrist in hospitalised patients may assist in the detection of infection. Intern Med J 2020; 50:685-690. [PMID: 31908128 PMCID: PMC7318648 DOI: 10.1111/imj.14748] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 12/07/2019] [Accepted: 12/13/2019] [Indexed: 12/29/2022]
Abstract
Background Measuring temperature has always been a key observation in the diagnosis of infection. No studies have examined the usefulness of measuring temperature at the wrist to detect infection. Aim We sought to determine whether a watch measuring wrist temperature could accurately identify patients who are infected. Methods Prospective cross‐sectional pilot study of temperature monitoring in an unselected patients in a tertiary referral adult nephrology unit. Results One hundred and four data recording sessions revealed 88 useful data sets, with recording failures in the others. Patients were retrospectively classified as having no infection (Group A, n = 60), clinically diagnosed infection with less than 24 h of treatment with antibiotics (Group B, n = 5), and clinically diagnosed infection with greater than 24 h on antibiotics (Group C, n = 23). There was a significantly higher average maximum temperature in Group B (mean (SEM)) 38°C (0.6) compared with Groups A (36.1°C (0.1)) and C (36.3°C (0.3)). Based on receiver operating characteristics (ROC) a cut‐off temperature of ≥37.5°C gave sensitivity 80% and specificity 98%. Mean electrodermal activity was significantly higher in Groups B and C. Conclusions ROC of peripheral skin temperature measurements suggest that such a device may identify many patients requiring treatment for infection. This proof of principle study showed value in using a wearable device in the detection of infection and its potential as an early warning or monitoring device.
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Affiliation(s)
- Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia.,Department of Medicine, The University of Melbourne, Melbourne, Victoria, Australia
| | - Jennifer H Yo
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia
| | - Connie Karschimkus
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia.,The Nursing Hub, The Royal Melbourne Hospital, Melbourne, Victoria, Australia
| | - Frank Volpato
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia
| | - Steve Christov
- Guidance Group, The Royal Melbourne Hospital, Melbourne, Victoria, Australia
| | - Edward R Smith
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia.,Department of Medicine, The University of Melbourne, Melbourne, Victoria, Australia
| | - Tim D Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia.,Department of Medicine, The University of Melbourne, Melbourne, Victoria, Australia
| | - Leon J Worth
- Victorian Healthcare Associated Infection Surveillance System (VICNISS) Coordinating Centre, Doherty Institute, Melbourne, Victoria, Australia.,Sir Peter MacCallum Department of Oncology, National Centre for Infections in Cancer, Victorian Comprehensive Cancer Centre, University of Melbourne, Melbourne, Victoria, Australia
| | - Paul Champion De Crespigny
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia.,Department of Medicine, The University of Melbourne, Melbourne, Victoria, Australia
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Bressendorff I, Hansen D, Pasch A, Holt SG, Schou M, Brandi L, Smith ER. The effect of increasing dialysate magnesium on calciprotein particles, inflammation and bone markers: post hoc analysis from a randomized controlled clinical trial. Nephrol Dial Transplant 2019; 36:713-721. [DOI: 10.1093/ndt/gfz234] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Indexed: 12/21/2022] Open
Abstract
Abstract
Background
The formation of calciprotein particles (CPPs) may be an important component of the humoral defences against ectopic calcification. Although magnesium (Mg) has been shown to delay the transition of amorphous calcium-/phosphate-containing primary CPP (CPP-1) to crystalline apatite-containing secondary CPP (CPP-2) ex vivo, effects on the endogenous CPP pool are unknown.
Methods
We used post hoc analyses from a randomized double-blind parallel-group controlled clinical trial of 28 days treatment with high dialysate Mg of 2.0 mEq/L versus standard dialysate Mg of 1.0 mEq/L in 57 subjects undergoing maintenance hemodialysis for end-stage kidney disease. CPP load, markers of systemic inflammation and bone turnover were measured at baseline and follow-up.
Results
After 28 days of treatment with high dialysate Mg, serum total CPP (−52%), CPP-1 (−42%) and CPP-2 (−68%) were lower in the high Mg group (all P < 0.001) but were unchanged in the standard dialysate Mg group. Tumour necrosis factor-α (−20%) and interleukin-6 (−22%) were also reduced with high dialysate Mg treatment (both P < 0.01). High dialysate Mg resulted in higher levels of bone-specific alkaline phosphatase (a marker of bone formation) (+17%) but lower levels of tartrate-resistant acid phosphatase 5 b (a marker of bone resorption; −33%) (both P < 0.01). Inflammatory cytokines and bone turnover markers were unchanged in the standard dialysate Mg group over the same period.
Conclusions
In this exploratory analysis, increasing dialysate Mg was associated with reduced CPP load and systemic inflammation and divergent changes in markers of bone formation and resorption.
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Affiliation(s)
- Iain Bressendorff
- Department of Endocrinology and Nephrology, Nordsjællands Hospital, Hillerød, Denmark
- Department of Nephrology, Herlev and Gentofte Hospital, Herlev, Denmark
| | - Ditte Hansen
- Department of Nephrology, Herlev and Gentofte Hospital, Herlev, Denmark
| | - Andreas Pasch
- Calciscon AG, Nidau, Switzerland
- Insitute for Physiology and Pathophysiology, Johannes Kepler University Linz, Linz, Austria
| | - Stephen G Holt
- Department of Nephrology, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Morten Schou
- Department of Cardiology, Herlev and Gentofte Hospital, Herlev, Denmark
| | - Lisbet Brandi
- Department of Endocrinology and Nephrology, Nordsjællands Hospital, Hillerød, Denmark
| | - Edward R Smith
- Department of Nephrology, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
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Smith ER, Hewitson TD, Holt SG. Diagnostic Tests for Vascular Calcification. Adv Chronic Kidney Dis 2019; 26:445-463. [PMID: 31831123 DOI: 10.1053/j.ackd.2019.07.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 07/22/2019] [Accepted: 07/28/2019] [Indexed: 02/06/2023]
Abstract
Vascular calcification (VC) is the heterogeneous endpoint of multiple vascular insults, which varies by arterial bed, the layer of the arterial wall affected, and is propagated by diverse cellular and biochemical mechanisms. A variety of in vivo and ex vivo techniques have been applied to the analysis of VC in preclinical studies, but clinical examination has principally relied on a number of noninvasive and invasive imaging modalities for detection and quantitation. Most imaging methods suffer from suboptimal spatial resolution, leading to the inability to distinguish medial from intimal VC and insufficient sensitivity to detect microcalcifications that are indicative of active mineral deposition and of vulnerable plaques which may be prone to rupture. Serum biomarkers lack specificity for VC and cannot discriminate pathology. Overall, uncertainties surrounding the sensitivity and specificity of different VC testing modalities, the absence of a clear cause-effect relationship, and lack of any evidence-based diagnostic or therapeutic protocols in relation to VC testing in chronic kidney disease has yielded weak or ungraded recommendations for their use in clinical practice. While VC is recognized as a key manifestation of chronic kidney disease-mineral and bone disorder and those with an increasing burden of VC are considered to be at higher cardiovascular risk, routine screening is not currently recommended.
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Kirkham FA, Rankin P, Parekh N, Holt SG, Rajkumar C. Aortic stiffness and central systolic pressure are associated with ambulatory orthostatic BP fall in chronic kidney disease. J Nephrol 2019; 33:317-324. [PMID: 31598911 DOI: 10.1007/s40620-019-00655-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 09/24/2019] [Indexed: 10/25/2022]
Abstract
OBJECTIVE Orthostatic hypotension (OH) has a significant association with cardiovascular disease. OH becomes more common in older age, as does arterial stiffness, shown to be independently associated with impaired baroreflex sensitivity and OH. Measurement of arterial compliance and central blood pressures are increasingly important, with evidence that central BP more closely correlates to end-organ damage and mortality than peripheral measurements. Patients with chronic kidney disease (CKD) are high risk for cardiovascular events, which can be predicted through measures of arterial compliance. We hypothesised that OH is associated with arterial stiffness and central blood pressure in CKD patients. DESIGN/SETTING We tested this hypothesis within the arterial compliance and oxidant stress as predictors of loss of renal function, morbidity and mortality in chronic kidney disease (ACADEMIC) study, a single-centre prospective observational study of the progression of arterial stiffness and renal function. PARTICIPANTS One hundred and forty-six patients with CKD 3 or 4. MEASUREMENTS Twenty-four-hour ambulatory BP monitoring with postural sensing (DIASYS Integra 2, Novacor France); central systolic and diastolic BP (cSBP and cDBP) and aortic Augmentation Index using Sphygmocor® (Atcor, Australia); Carotid-femoral pulse wave velocity (cfPWV) using Complior® (ALAM Medical, France). RESULTS Twenty-three patients had a postural SBP fall (prevalence 15.8%), with mean drop 7 mmHg. Patients with OH had higher cfPWV (15.2 m/s vs 12.7 m/s in patients without OH, p < 0.001) and central SBP (147.5 vs 135.7, p = 0.012). Regression analysis gave an odds ratio (OR) of orthostatic SBP fall for cfPWV of 1.46 (95% CI 1.16-1.84, p = 0.001) and 1.03 for cSBP (95% CI 1.004-1.06, p = 0.024) after adjustment for cardiovascular risk factors. CONCLUSION Aortic stiffness and central SBP are independently associated with orthostatic SBP fall in CKD patients. This suggests that enhanced arterial stiffness may be an underlying mechanism in baroreflex dysfunction, and may partly explain the vascular risk in CKD patients.
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Affiliation(s)
- Frances A Kirkham
- Department of Elderly Care and Stroke Medicine, Brighton and Sussex University Hospitals Trust, Brighton, BN2 5BE, UK.
| | - Philip Rankin
- Department of Elderly Care and Stroke Medicine, Brighton and Sussex University Hospitals Trust, Brighton, BN2 5BE, UK
| | - Nikesh Parekh
- Department of Elderly Care and Stroke Medicine, Brighton and Sussex University Hospitals Trust, Brighton, BN2 5BE, UK.,Department of Medicine, Brighton and Sussex Medical School, University of Sussex, Brighton, UK
| | - Stephen G Holt
- Department of Medicine, Brighton and Sussex Medical School, University of Sussex, Brighton, UK.,Department of Nephrology, Brighton and Sussex University Hospitals Trust, Brighton, UK
| | - Chakravarthi Rajkumar
- Department of Elderly Care and Stroke Medicine, Brighton and Sussex University Hospitals Trust, Brighton, BN2 5BE, UK.,Department of Medicine, Brighton and Sussex Medical School, University of Sussex, Brighton, UK
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23
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Ruderman I, Holt SG, Kirkland GS, Maslen S, Hawley CM, Oliver V, Krishnasamy R, Gray NA, Talaulikar GS, Nelson CL, Rajaram Y, Gock H, Au E, Elder GJ, Mainra R, Toussaint ND. Outcomes of cinacalcet withdrawal in Australian dialysis patients. Intern Med J 2019; 49:48-54. [PMID: 29992701 DOI: 10.1111/imj.14036] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 06/30/2018] [Indexed: 12/24/2022]
Abstract
BACKGROUND Secondary hyperparathyroidism (SHPT) in chronic kidney disease is associated with cardiovascular and bone pathology. Measures to achieve parathyroid hormone (PTH) target values and control biochemical abnormalities associated with SHPT require complex therapies, and severe SHPT often requires parathyroidectomy or the calcimimetic cinacalcet. In Australia, cinacalcet was publicly funded for dialysis patients from 2009 to 2015 when funding was withdrawn following publication of the EVOLVE study, which resulted in most patients on cinacalcet ceasing therapy. We examined the clinical and biochemical outcomes associated with this change at Australian renal centres. AIM To assess changes to biochemical and clinical outcomes in dialysis patients following cessation of cinacalcet. METHODS We conducted a retrospective study of dialysis patients who ceased cinacalcet after August 2015 in 11 Australian units. Clinical outcomes and changes in biochemical parameters were assessed over a 24- and 12-month period, respectively, from cessation of cinacalcet. RESULTS A total of 228 patients was included (17.7% of all dialysis patients from the units). Patients were aged 63 ± 15 years with 182 patients on haemodialysis and 46 on peritoneal dialysis. Over 24 months following cessation of cinacalcet, we observed 26 parathyroidectomies, 3 episodes of calciphylaxis, 8 fractures and 50 deaths. Eight patients recommenced cinacalcet, meeting criteria under a special access scheme. Biochemical changes from baseline to 12 months after cessation included increased levels of serum PTH from 54 (interquartile range 27-90) pmol/L to 85 (interquartile range 41-139) pmol/L (P < 0.0001), serum calcium from 2.3 ± 0.2 mmol/L to 2.5 ± 0.1 mmol/L (P < 0.0001) and alkaline phosphatase from 123 (92-176) IU/L to 143 (102-197) IU/L (P < 0.0001). CONCLUSION Significant increases in serum PTH, calcium and alkaline phosphatase occurred over a 12-month period following withdrawal of cinacalcet. Longer-term follow up will determine if these biochemical and therapeutic changes are associated with altered rates of parathyroidectomies and cardiovascular mortality and morbidity.
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Affiliation(s)
- Irene Ruderman
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Victoria, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Victoria, Australia
| | - Geoffrey S Kirkland
- Department of Nephrology, Royal Hobart Hospital, Hobart, Tasmania, Australia
| | - Sophie Maslen
- Department of Nephrology, Royal Hobart Hospital, Hobart, Tasmania, Australia
| | - Carmel M Hawley
- Department of Nephrology, Princess Alexandra Hospital, Brisbane, Queensland, Australia
| | - Veronica Oliver
- Department of Nephrology, Princess Alexandra Hospital, Brisbane, Queensland, Australia
| | - Rathika Krishnasamy
- Department of Nephrology, Sunshine Coast Hospital University Hospital, Sunshine Coast, Queensland, Australia
| | - Nicholas A Gray
- Department of Nephrology, Sunshine Coast Hospital University Hospital, Sunshine Coast, Queensland, Australia
| | - Girish S Talaulikar
- Department of Nephrology, Canberra Hospital, Canberra, Australian Capital Territory, Australia
| | - Craig L Nelson
- Department of Nephrology, Western Health, Melbourne, Victoria, Australia.,Department of Medicine, Western Health, Melbourne, Victoria, Australia.,Western Health Chronic Disease Alliance, Melbourne, Victoria, Australia
| | - Yogeshwar Rajaram
- Department of Nephrology, St Vincent's Health, Melbourne, Victoria, Australia
| | - Hilton Gock
- Department of Nephrology, St Vincent's Health, Melbourne, Victoria, Australia
| | - Eric Au
- Department of Nephrology, Westmead Hospital, Sydney, New South Wales, Australia
| | - Grahame J Elder
- Department of Nephrology, Westmead Hospital, Sydney, New South Wales, Australia.,Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
| | - Rahul Mainra
- Department of Nephrology, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
| | - Nigel D Toussaint
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Victoria, Australia
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24
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Hewitson TD, Holt SG, Samuel CS, Wigg B, Smith ER. Profiling histone modifications in the normal mouse kidney and after unilateral ureteric obstruction. Am J Physiol Renal Physiol 2019; 317:F606-F615. [DOI: 10.1152/ajprenal.00262.2019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Posttranslational modification of nucleosomal histones is a major determinant of chromatin structure and gene activity. In the present study, we hypothesized that unilateral ureteric obstruction (UUO), a widely used model of tubulointerstitial injury, would be associated with a distinct pattern of histone modifications (marks) in the kidney. Mass spectrometry was used to profile 63 different histone marks in normal mouse kidneys and those after 10 days of UUO. A subsequent histochemical analysis further examined examples of specific marks that changed significantly after UUO for which antisera are available. Histone marks were much more widely distributed and abundant in the normal kidney than is usually appreciated. Although aggregate analysis of the mass spectrometry results revealed net differences between control and UUO groups, residue-specific variations were subtle. Of the 16/63 significant changes ( P < 0.05), only 8 changes were quantitatively different by >5%. Nevertheless, we identified several that are not usually examined in the kidney, including marks in the globular domain of core histones (H3:K79), linker histones (H1.4), and histone variants (H3.1:K27 and H3.3:K27). In several cases, there were complementary changes in different marks on the same amino acid. Using H3:K79ME2 as an example, mark enrichment was heterogeneous but largely colocalized with active transcription in a subset of tubular pathology. In conclusion, our study highlights the importance of unbiased screening in examining histone marks. Simultaneous changes in multiple marks on the same amino acid indicate a coordinated histone mark signature. The heterogeneous enrichment of marks, even within the same tubule, highlights the importance of regulatory context.
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Affiliation(s)
- Timothy D. Hewitson
- Department of Nephrology, Royal Melbourne Hospital, Parkville, Victoria, Australia
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia
| | - Stephen G. Holt
- Department of Nephrology, Royal Melbourne Hospital, Parkville, Victoria, Australia
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia
| | - Chrishan S. Samuel
- Biomedicine Discovery Institute and Department of Pharmacology, Monash University, Clayton, Victoria, Australia
| | - Belinda Wigg
- Department of Nephrology, Royal Melbourne Hospital, Parkville, Victoria, Australia
| | - Edward R. Smith
- Department of Nephrology, Royal Melbourne Hospital, Parkville, Victoria, Australia
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Parkville, Victoria, Australia
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25
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Barraclough KA, Gleeson A, Holt SG, Agar JW. Green dialysis survey: Establishing a baseline for environmental sustainability across dialysis facilities in Victoria, Australia. Nephrology (Carlton) 2019; 24:88-93. [PMID: 29094785 DOI: 10.1111/nep.13191] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2017] [Indexed: 11/29/2022]
Abstract
AIM The Green Dialysis Survey aimed to (i) establish a baseline for environmental sustainability (ES) across Victorian dialysis facilities; and (ii) guide future initiatives to reduce the environmental impact of dialysis delivery. METHODS Nurse unit managers of all Victorian public dialysis facilities received an online link to the survey, which asked 107 questions relevant to the ES of dialysis services. RESULTS Responses were received from 71/83 dialysis facilities in Victoria (86%), representing 628/660 dialysis chairs (95%). Low energy lighting was present in 13 facilities (18%), 18 (25%) recycled reverse osmosis water and seven (10%) reported use of renewable energy. Fifty-six facilities (79%) performed comingled recycling but only 27 (38%) recycled polyvinyl chloride plastic. A minority educated staff in appropriate waste management (n = 30;42%) or formally audited waste generation and segregation (n = 19;27%). Forty-four (62%) provided secure bicycle parking but only 33 (46%) provided shower and changing facilities. There was limited use of tele- or video-conferencing to replace staff meetings (n = 19;27%) or patient clinic visits (n = 13;18%). A minority considered ES in procurement decisions (n = 28;39%) and there was minimal preparedness to cope with climate change. Only 39 services (49%) confirmed an ES policy and few had ever formed a green group (n = 14; 20%) or were currently undertaking a green project (n = 8;11%). Only 15 facilities (21%) made formal efforts to raise awareness of ES. CONCLUSION This survey provides a baseline for practices that potentially impact the environmental sustainability of dialysis units in Victoria, Australia. It also identifies achievable targets for attention.
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Affiliation(s)
- Katherine A Barraclough
- Department of Nephrology, Royal Melbourne Hospital, Melbourne, Victoria, Australia.,Department of Health and Human Services, Victorian Renal Clinical Network, Safer Care Victoria, Melbourne, Victoria, Australia
| | - Alice Gleeson
- Department of Health and Human Services, Victorian Renal Clinical Network, Safer Care Victoria, Melbourne, Victoria, Australia
| | - Stephen G Holt
- Department of Nephrology, Royal Melbourne Hospital, Melbourne, Victoria, Australia.,Department of Health and Human Services, Victorian Renal Clinical Network, Safer Care Victoria, Melbourne, Victoria, Australia
| | - John Wm Agar
- Department of Renal Medicine, University Hospital Geelong, Barwon Health, Geelong, Victoria, Australia
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26
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Sharma AK, Toussaint ND, Elder GJ, Masterson R, Holt SG, Robertson PL, Ebeling PR, Baldock P, Miller RC, Rajapakse CS. Magnetic resonance imaging based assessment of bone microstructure as a non-invasive alternative to histomorphometry in patients with chronic kidney disease. Bone 2018; 114:14-21. [PMID: 29860153 DOI: 10.1016/j.bone.2018.05.029] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 05/22/2018] [Accepted: 05/29/2018] [Indexed: 01/16/2023]
Abstract
BACKGROUND Chronic kidney disease (CKD) adversely affects bone microarchitecture and increases fracture risk. Historically, bone biopsy has been the 'gold standard' for evaluating renal bone disease but is invasive and infrequently performed. High-resolution magnetic resonance imaging (MRI) quantifies bone microarchitecture noninvasively. In patients with CKD, it has not been compared with results derived from bone biopsy or with imaging using dual energy X-ray absorptiometry (DXA). METHODS Fourteen patients with end-stage kidney disease (ESKD) underwent MRI at the distal tibia, bone mineral density (BMD) by dual energy X-ray absorptiometry (DXA; hip and spine) and transiliac bone biopsies with histomorphometry and microcomputed tomography (micro-CT). All patients had biomarkers of mineral metabolism. Associations were determined by Spearman's or Pearson's rank correlation coefficients. RESULTS MRI indices of trabecular network integrity, surface to curve ratio (S/C) and erosion index (EI), correlated to histomorphometric trabecular bone volume (S/C r = 0.85, p = 0.0003; EI r = -0.82, p = 0.001), separation (S/C r = -0.58, p = 0.039; EI r = 0.79, p = 0.0012) and thickness (S/C, r = 0.65, p = 0.017). MRI EI and trabecular thickness (TbTh) also correlated to micro-CT trabecular separation (EI r = 0.63, p = 0.02; TbTh r = -0.60, p = 0.02). Significant correlations were observed between histomorphometric mineralization and turnover indices and various MRI parameters. MRI-derived trabecular parameters were also significantly related to femoral neck BMD. CONCLUSIONS This study highlights the heterogeneity of bone microarchitecture at differing skeletal sites. MRI demonstrates significant, relevant associations to important bone biopsy and DXA indices and warrants further investigation to assess its potential to non-invasively evaluate changes in bone structure and quality over time.
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Affiliation(s)
- Ashish K Sharma
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia; Department of Medicine (RMH), University of Melbourne, Parkville, Australia.
| | - Nigel D Toussaint
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia; Department of Medicine (RMH), University of Melbourne, Parkville, Australia
| | - Grahame J Elder
- Department of Renal Medicine, Westmead Hospital, Westmead, Australia; Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, Darlinghurst, Australia
| | - Rosemary Masterson
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia; Department of Medicine (RMH), University of Melbourne, Parkville, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia; Department of Medicine (RMH), University of Melbourne, Parkville, Australia
| | - Patricia L Robertson
- Department of Medicine (RMH), University of Melbourne, Parkville, Australia; Department of Radiology, The Royal Melbourne Hospital, Parkville, Australia
| | | | - Paul Baldock
- Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, Darlinghurst, Australia
| | - Rhiannon C Miller
- Departments of Radiology and Orthopaedic Surgery, University of Pennsylvania, PA, USA
| | - Chamith S Rajapakse
- Departments of Radiology and Orthopaedic Surgery, University of Pennsylvania, PA, USA
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Tan SJ, Chu MM, Toussaint ND, Cai MM, Hewitson TD, Holt SG. High-intensity physical exercise increases serum α-klotho levels in healthy volunteers. J Circ Biomark 2018; 7:1849454418794582. [PMID: 30147756 PMCID: PMC6100126 DOI: 10.1177/1849454418794582] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Accepted: 07/02/2018] [Indexed: 01/16/2023] Open
Abstract
The recently discovered klotho proteins have roles in a diverse range of metabolic processes with the oldest protein, α-klotho, implicated in various cellular pathways in energy, glucose, and phosphate metabolism. Circulating soluble klotho (sKl), derived from membrane α-klotho cleavage, not only has effects on ion channels and insulin signaling pathways, but is inversely associated with mortality. Effects of physical exercise on sKl have not been well studied. The effect of a single high-intensity standardized exercise on sKl and serum phosphate (sPi) levels in healthy adults was investigated. A standard Bruce protocol treadmill exercise was undertaken by 10 fasting healthy volunteers. sKl, sPi, and blood glucose levels were measured in samples collected 1-week prior, immediately pre (Tpre), 0 (Tpost), 30 (T30), 240 (T240) min, and 1-week after exercise. Median (interquartile range) age of participants was 47.5 (44-51) years; five (50%) were male. All study participants achieved at least 90% predicted maximum heart rate (MHR). sKl increased acutely after exercise (Tpre median 448 pg/mL vs. Tpost median 576 pg/mL; p < 0.01). There was a nonsignificant sPi decline at T30 (Tpre 0.94 ± 0.12 mmol/L vs. T30 0.83 ± 0.22 mmol/L). Exercise led to a reduction in blood glucose by T240 with median glucose levels at Tpre, Tpost, T30, and T240 of 6.0, 6.5, 6.3, and 5.7 mmol/L, respectively. In conclusion, a single high-intensity exercise session is associated with a transient increase in sKl, a delayed reduction in blood glucose, and a nonsignificant decrease in sPi levels in healthy adults. The evaluation of long-term effects of cardiovascular fitness programs on sKl and sPi in healthy individuals and disease cohorts are required to identify potential lifestyle modifications to help improve chronic disease management and long-term outcomes.
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Affiliation(s)
- Sven-Jean Tan
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, VIC, Australia.,Department of Medicine, The University of Melbourne, Parkville, VIC, Australia
| | - Melissa M Chu
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, VIC, Australia
| | - Nigel D Toussaint
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, VIC, Australia.,Department of Medicine, The University of Melbourne, Parkville, VIC, Australia
| | - Michael Mx Cai
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, VIC, Australia.,Department of Medicine, The University of Melbourne, Parkville, VIC, Australia
| | - Tim D Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, VIC, Australia.,Department of Medicine, The University of Melbourne, Parkville, VIC, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, VIC, Australia.,Department of Medicine, The University of Melbourne, Parkville, VIC, Australia
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28
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Sharma AK, Toussaint ND, Elder GJ, Rajapakse CS, Holt SG, Baldock P, Robertson PL, Ebeling PR, Sorci OR, Masterson R. Changes in bone microarchitecture following kidney transplantation-Beyond bone mineral density. Clin Transplant 2018; 32:e13347. [PMID: 29984421 DOI: 10.1111/ctr.13347] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 07/03/2018] [Indexed: 11/30/2022]
Abstract
Bone disease in kidney transplant recipients (KTRs) is characterized by bone mineral density (BMD) loss but bone microarchitecture changes are poorly defined. In this prospective cohort study, we evaluated bone microarchitecture using non-invasive imaging modalities; high-resolution magnetic resonance imaging (MRI), peripheral quantitative computed tomography (pQCT), dual energy X-ray absorptiometry (DXA), and the trabecular bone score (TBS) following kidney transplantation. Eleven KTRs (48.3 ± 11.2 years) underwent MRI (tibia), pQCT (radius) and DXA at baseline and 12 months post-transplantation. Transiliac bone biopsies, performed at transplantation, showed 70% of patients with high/normal bone turnover. Compared with baseline, 12-month MRI showed deterioration in indices of trabecular network integrity-surface to curve ratio (S/C; -15%, P = 0.03) and erosion index (EI; +19%, P = 0.01). However, cortical area increased (+10.3%, P = 0.04), with a non-significant increase in cortical thickness (CtTh; +7.8%, P = 0.06). At 12 months, parathyroid hormone values (median 10.7 pmol/L) correlated with improved S/C (r = 0.75, P = 0.009) and EI (r = -0.71, P = 0.01) while osteocalcin correlated with CtTh (r = 0.72, P = 0.02) and area (r = 0.70, P = 0.02). TBS decreased from baseline (-5.1%, P = 0.01) with no significant changes in BMD or pQCT. These findings highlight a post-transplant deterioration in trabecular bone quality detected by MRI and TBS, independent of changes in BMD, underlining the potential utility of these modalities in evaluating bone microarchitecture in KTRs.
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Affiliation(s)
- Ashish K Sharma
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Victoria, Australia.,Department of Medicine (RMH), University of Melbourne, Parkville, Victoria, Australia
| | - Nigel D Toussaint
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Victoria, Australia.,Department of Medicine (RMH), University of Melbourne, Parkville, Victoria, Australia
| | - Grahame J Elder
- Department of Renal Medicine, Westmead Hospital, Westmead, Sydney, Australia.,Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Chamith S Rajapakse
- Departments of Radiology and Orthopaedic Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Victoria, Australia.,Department of Medicine (RMH), University of Melbourne, Parkville, Victoria, Australia
| | - Paul Baldock
- Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Patricia L Robertson
- Department of Medicine (RMH), University of Melbourne, Parkville, Victoria, Australia.,Department of Radiology, The Royal Melbourne Hospital, Parkville, Victoria, Australia
| | | | - Olivia R Sorci
- Departments of Radiology and Orthopaedic Surgery, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Rosemary Masterson
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Victoria, Australia.,Department of Medicine (RMH), University of Melbourne, Parkville, Victoria, Australia
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Cai MMX, Smith ER, Kent A, Huang L, Hewitson TD, McMahon LP, Holt SG. Calciprotein Particle Formation in Peritoneal Dialysis Effluent Is Dependent on Dialysate Calcium Concentration. Perit Dial Int 2018; 38:286-292. [PMID: 29793980 DOI: 10.3747/pdi.2017.00163] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 02/05/2018] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND The accumulation of fetuin-A-containing calciprotein particles (CPP) in the serum of patients with renal disease and those with chronic inflammation may be involved in driving sterile inflammation and extraosseous mineral deposition. We previously showed that both fetuin-A and CPP were present in the peritoneal dialysis (PD) effluent of stable PD patients. It is unknown whether different PD fluids might affect the formation of CPP in vivo. METHOD Peritoneal effluent from 12 patients was collected after a 6-hour dwell with 7 different commercial PD fluids. Calciprotein particles and inflammatory cytokines were measured by flow cytometry. RESULTS High inter-subject variability in CPP concentration was observed. Peritoneal dialysis fluids containing 1.75 mmol/L calcium were associated with enhanced formation of CPP in vivo, compared with fluids containing 1.25 mmol/L calcium. Osmotic agent, fluid pH, and glucose concentration did not affect CPP formation. Peritoneal dialysis effluent CPP levels were not associated with changes in inflammatory cytokines. CONCLUSION High calcium-containing PD fluids favor intraperitoneal CPP formation. This finding may have relevance for future PD fluid design.
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Affiliation(s)
- Michael M X Cai
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Australia .,Department of Medicine (Royal Melbourne Hospital), University of Melbourne, Melbourne, Australia
| | - Edward R Smith
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Australia.,Department of Medicine (Royal Melbourne Hospital), University of Melbourne, Melbourne, Australia
| | - Annette Kent
- Eastern Health Integrated Renal Services, Eastern Health, Melbourne, Australia
| | - Louis Huang
- Eastern Health Integrated Renal Services, Eastern Health, Melbourne, Australia.,Eastern Health Clinical School, Monash University, Melbourne, Australia
| | - Timothy D Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Australia.,Department of Medicine (Royal Melbourne Hospital), University of Melbourne, Melbourne, Australia
| | - Lawrence P McMahon
- Eastern Health Integrated Renal Services, Eastern Health, Melbourne, Australia.,Eastern Health Clinical School, Monash University, Melbourne, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Australia.,Department of Medicine (Royal Melbourne Hospital), University of Melbourne, Melbourne, Australia
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Sharma AK, Toussaint ND, Masterson R, Holt SG, Rajapakse CS, Ebeling PR, Mohanty ST, Baldock P, Elder GJ. Deterioration of Cortical Bone Microarchitecture: Critical Component of Renal Osteodystrophy Evaluation. Am J Nephrol 2018; 47:376-384. [PMID: 29791896 DOI: 10.1159/000489671] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 03/27/2018] [Indexed: 01/23/2023]
Abstract
BACKGROUND Cortical bone is a significant determinant of bone strength and its deterioration contributes to bone fragility. Thin cortices and increased cortical porosity have been noted in patients with chronic kidney disease (CKD), but the "Turnover Mineralization Volume" classification of renal osteodystrophy does not emphasize cortical bone as a key parameter. We aimed to assess trabecular and cortical bone microarchitecture by histomorphometry and micro-CT in patients with CKD G5 and 5D (dialysis). METHODS Transiliac bone biopsies were performed in 14 patients undergoing kidney transplantation (n = 12) and parathyroidectomy (n = 2). Structural parameters were analysed by histomorphometry and micro-CT including trabecular bone volume, thickness (TbTh), number (TbN) and separation and cortical thickness (CtTh) and porosity (CtPo). Indices of bone remodelling and mineralisation were obtained and relationships to bone biomarkers examined. Associations were determined by Spearman's or Pearson's rank correlation coefficients. RESULTS By micro-CT, trabecular parameters were within normal ranges in most patients, but all patients showed very low CtTh (127 ± 44 µm) and high CtPo (60.3 ± 22.5%). CtPo was inversely related to TbN (r = -0.56; p = 0.03) by micro-CT and to TbTh (r = -0.60; p = 0.024) by histomorphometry and correlated to parathyroid hormone values (r = 0.62; p = 0.021). By histomorphometry, bone turnover was high in 50%, low in 21% and normal in 29%, while 36% showed abnormal patterns of mineralization. Significant positive associations were observed between osteoblast surface, osteoclast surface, mineralization surface and bone turnover markers. CONCLUSIONS Deterioration of cortical -microarchitecture despite predominantly normal trabecular parameters reinforces the importance of comprehensive cortical evaluation in patients with CKD.
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Affiliation(s)
- Ashish K Sharma
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Victoria, Australia
- Department of Medicine (RMH), University of Melbourne, Parkville, Victoria, Australia
| | - Nigel D Toussaint
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Victoria, Australia
- Department of Medicine (RMH), University of Melbourne, Parkville, Victoria, Australia
| | - Rosemary Masterson
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Victoria, Australia
- Department of Medicine (RMH), University of Melbourne, Parkville, Victoria, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Victoria, Australia
- Department of Medicine (RMH), University of Melbourne, Parkville, Victoria, Australia
| | - Chamith S Rajapakse
- Departments of Radiology and Orthopaedic Surgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | - Sindhu T Mohanty
- Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Paul Baldock
- Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
| | - Grahame J Elder
- Osteoporosis and Bone Biology Division, Garvan Institute of Medical Research, Darlinghurst, New South Wales, Australia
- Department of Renal Medicine, Westmead Hospital, Westmead, New South Wales, Australia
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Ruderman I, Smith ER, Toussaint ND, Hewitson TD, Holt SG. Longitudinal changes in bone and mineral metabolism after cessation of cinacalcet in dialysis patients with secondary hyperparathyroidism. BMC Nephrol 2018; 19:113. [PMID: 29764395 PMCID: PMC5952622 DOI: 10.1186/s12882-018-0910-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 04/27/2018] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND The calcimimetic agent cinacalcet is effective for the management of secondary hyperparathyroidism (SHPT) in dialysis patients. Changes to reimbursement of cinacalcet in Australia provided an opportunity to assess effects of medication cessation on biochemical and clinical outcomes in dialysis patients, including changes to novel biomarkers such as calciprotein particles (CPP). CPP are nanoparticles of mineral and protein in the circulation associated with increased vascular calcification in patients with chronic kidney disease. METHODS Dialysis patients from a single center who ceased cinacalcet between August 2015 and March 2016 were included in a prospective observational study. Bloods were taken at the time of cessation of cinacalcet and at 1, 6 and 12 months. Clinical and biochemical outcomes were compared with an age- and gender-matched cohort of cinacalcet-naïve dialysis patients. RESULTS Sixty-two patients participated in the study. Mean age was 69.6 ± 13.2 years. Biochemical changes over 12 months following cessation of cinacalcet included an increase in serum parathyroid hormone (PTH) (42.2 [IQR 27.8-94.6] pmol/L to 114.8 [83.9-159.1] pmol/L [p < 0.001]), serum calcium (2.31 ± 0.21 mmol/L to 2.46 ± 0.14 mmol/L [p < 0.001]) and primary CPP (CPP-I) (p = 0.002). Changes in CPP were associated with an increase in PTH (p = 0.007), calcium (p = 0.002) and ferritin (p = 0.02) but a reduction in serum albumin (p = 0.001). Over the 12-month period, there were two fractures, five cardiovascular events, one episode of calciphylaxis, and one parathyroidectomy, with a mortality rate of 19% (n = 13). CONCLUSION Uniquely we report the effects of cinacalcet withdrawal in a real world setting with demonstrated increases in PTH, serum calcium and CPP subsets, novel CKD-MBD related factors, over a 12-month period.
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Affiliation(s)
- Irene Ruderman
- Department of Nephrology, The Royal Melbourne Hospital, 300 Grattan St, Parkville, Victoria, 3050, Australia. .,Department of Medicine (RMH), The University of Melbourne, Melbourne, Victoria, Australia.
| | - Edward R Smith
- Department of Nephrology, The Royal Melbourne Hospital, 300 Grattan St, Parkville, Victoria, 3050, Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Victoria, Australia
| | - Nigel D Toussaint
- Department of Nephrology, The Royal Melbourne Hospital, 300 Grattan St, Parkville, Victoria, 3050, Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Victoria, Australia
| | - Tim D Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, 300 Grattan St, Parkville, Victoria, 3050, Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Victoria, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, 300 Grattan St, Parkville, Victoria, 3050, Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Victoria, Australia
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Ruderman I, Holt SG, Hewitson TD, Smith ER, Toussaint ND. Current and potential therapeutic strategies for the management of vascular calcification in patients with chronic kidney disease including those on dialysis. Semin Dial 2018; 31:487-499. [PMID: 29733462 DOI: 10.1111/sdi.12710] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Patients with CKD have accelerated vascular stiffening contributing significantly to excess cardiovascular morbidity and mortality. Much of the arterial stiffening is thought to involve vascular calcification (VC), but the pathogenesis of this phenomenon is complex, resulting from a disruption of the balance between promoters and inhibitors of calcification in a uremic milieu, along with derangements in calcium and phosphate metabolic pathways. Management of traditional cardiovascular risk factors to reduce VC may be influential but has not been shown to significantly improve mortality. Control of mineral metabolism may potentially reduce the burden of VC, although using conventional approaches of restricting dietary phosphate, administering phosphate binders, and use of active vitamin D and calcimimetics, remains controversial because recommended biochemical targets are hard to achieve and clinical relevance hard to define. Increasing time on dialysis is perhaps another therapy with potential effectiveness in this area. Despite current treatments, cardiovascular morbidity and mortality remain high in this group. Novel therapies for addressing VC include magnesium and vitamin K supplementation, which are currently being investigated in large randomized control trials. Other therapeutic targets include crystallization inhibitors, ligand trap for activin receptors and BMP-7. This review summarizes current treatment strategies and therapeutic targets for the future management of VC in patients with CKD.
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Affiliation(s)
- Irene Ruderman
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Vic., Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Vic., Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Vic., Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Vic., Australia
| | - Tim D Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Vic., Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Vic., Australia
| | - Edward R Smith
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Vic., Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Vic., Australia
| | - Nigel D Toussaint
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Vic., Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Vic., Australia
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Abstract
Calciprotein particles (CPP) have emerged as nanoscale mediators of phosphate-induced toxicity in Chronic Kidney Disease (CKD). Uraemia favors ripening of the particle mineral content from the amorphous (CPP-I) to the crystalline state (CPP-II) but the pathophysiological significance of this transformation is uncertain. Clinical studies suggest an association between CPP ripening and inflammation, vascular dysfunction and mortality. Although ripening has been modelled in vitro, it is unknown whether particles synthesised in serum resemble their in vivo counterparts. Here we show that in vitro formation and ripening of CPP in uraemic serum is characterised by extensive physiochemical rearrangements involving the accretion of mineral, loss of surface charge and transformation of the mineral phase from a spherical arrangement of diffuse domains of amorphous calcium phosphate to densely-packed lamellar aggregates of crystalline hydroxyapatite. These physiochemical changes were paralleled by enrichment with small soluble apolipoproteins, complement factors and the binding of fatty acids. In comparison, endogenous CPP represent a highly heterogeneous mixture of particles with characteristics mostly intermediate to synthetic CPP-I and CPP-II, but are also uniquely enriched for carbonate-substituted apatite, DNA fragments, small RNA and microbe-derived components. Pathway analysis of protein enrichment predicted the activation of cell death and pro-inflammatory processes by endogenous CPP and synthetic CPP-II alike. This comprehensive characterisation validates the use of CPP-II generated in uraemic serum as in vitro equivalents of their endogenous counterparts and provides insight into the nature and pathological significance of CPP in CKD, which may act as vehicles for various bioactive ligands.
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Affiliation(s)
- Edward R Smith
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia; Department of Medicine - Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia.
| | - Tim D Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia; Department of Medicine - Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Eric Hanssen
- Melbourne Advanced Microscopy Facility and Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia; Department of Medicine - Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
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Ooi JD, Petersen J, Tan YH, Huynh M, Willett ZJ, Dudek NL, Eggenhuizen PJ, Loh KL, Watson KA, Gan PY, Handel A, Hudson BG, Fugger L, Power DA, Holt SG, Coates PT, Purcell AW, Gregersen JW, Holdsworth SR, La Gruta NL, Reid HH, Rossjohn J, Kitching AR. Dominant protection from HLA-mediated autoimmune disease is conferred by antigen specific regulatory T cells. Pathology 2018. [DOI: 10.1016/j.pathol.2017.12.112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Cai MMX, Smith ER, Tan SJ, Hewitson TD, Holt SG. The Role of Secondary Calciprotein Particles in the Mineralisation Paradox of Chronic Kidney Disease. Calcif Tissue Int 2017; 101:570-580. [PMID: 28861648 DOI: 10.1007/s00223-017-0313-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 08/09/2017] [Indexed: 12/12/2022]
Abstract
Mineralisation paradox is prevalent in chronic kidney disease and ageing where increased vascular calcification is accompanied by reduced bone mineralisation and osteopenia. Secondary calciprotein particles (CPP2), colloidal nanoparticles containing hydroxyapatite crystal stabilised by a protein shell, have been implicated in vascular calcification in chronic kidney disease. Here, we describe the effect of CPP2 on osteoblasts and vascular smooth muscle cells (VSMC) mineralisation in an in vitro model system. The mineralisation paradox can be simulated in vitro by the addition of phosphate ions (Pi, 3 mM) and CPP2 (10 µg/ml of Ca equivalent). Pi alone induced osteoblast mineralisation but had no effect on VSMC mineralisation. CPP2 alone had no effect on mineralisation in either cell line, but when combined with elevated Pi, reduced osteoblast-like mineralisation (P < 0.001) whilst induced VSMC mineralisation (P < 0.001). These results suggest that in an in vitro system the synergistic interaction between Pi and CPP2 could mimic the mineralisation paradox, and may provide a potential mechanistic link to explain these clinical observations.
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Affiliation(s)
- Michael M X Cai
- Department of Nephrology, Royal Melbourne Hospital, Parkville, VIC, Australia.
- Department of Medicine (RMH), University of Melbourne, Parkville, VIC, Australia.
| | - Edward R Smith
- Department of Nephrology, Royal Melbourne Hospital, Parkville, VIC, Australia
- Department of Medicine (RMH), University of Melbourne, Parkville, VIC, Australia
| | - Sven-Jean Tan
- Department of Nephrology, Royal Melbourne Hospital, Parkville, VIC, Australia
| | - Timothy D Hewitson
- Department of Nephrology, Royal Melbourne Hospital, Parkville, VIC, Australia
- Department of Medicine (RMH), University of Melbourne, Parkville, VIC, Australia
| | - Stephen G Holt
- Department of Nephrology, Royal Melbourne Hospital, Parkville, VIC, Australia
- Department of Medicine (RMH), University of Melbourne, Parkville, VIC, Australia
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Hewitson TD, Holt SG, Smith ER. Progression of Tubulointerstitial Fibrosis and the Chronic Kidney Disease Phenotype - Role of Risk Factors and Epigenetics. Front Pharmacol 2017; 8:520. [PMID: 28848437 PMCID: PMC5550676 DOI: 10.3389/fphar.2017.00520] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 07/24/2017] [Indexed: 12/11/2022] Open
Abstract
Although the kidney has capacity to repair after mild injury, ongoing or severe damage results in scarring (fibrosis) and an associated progressive loss of kidney function. However, despite its universal significance, evidence highlights a population based heterogeneity in the trajectory of chronic kidney disease (CKD) in these patients. To explain the heterogeneity of the CKD phenotype requires an understanding of the relevant risk factors for fibrosis. These factors include both the extrinsic nature of injury, and intrinsic factors such as age, gender, genetics, and perpetual activation of fibroblasts through priming. In many cases an additional level of regulation is provided by epigenetic mechanisms which integrate the various pro-fibrotic and anti-fibrotic triggers in fibrogenesis. In this review we therefore examine the various molecular and structural changes of fibrosis, and how they are influenced by extrinsic and intrinsic factors. Our aim is to provide a unifying hypothesis to help explain the transition from acute to CKD.
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Affiliation(s)
- Timothy D Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, MelbourneVIC, Australia.,Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, MelbourneVIC, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, MelbourneVIC, Australia.,Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, MelbourneVIC, Australia
| | - Edward R Smith
- Department of Nephrology, The Royal Melbourne Hospital, MelbourneVIC, Australia.,Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, MelbourneVIC, Australia
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Smith ER, Hewitson TD, Cai MMX, Aghagolzadeh P, Bachtler M, Pasch A, Holt SG. A novel fluorescent probe-based flow cytometric assay for mineral-containing nanoparticles in serum. Sci Rep 2017; 7:5686. [PMID: 28720774 PMCID: PMC5515983 DOI: 10.1038/s41598-017-05474-y] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 05/30/2017] [Indexed: 12/20/2022] Open
Abstract
Calciprotein particles, nanoscale aggregates of insoluble mineral and binding proteins, have emerged as potential mediators of phosphate toxicity in patients with Chronic Kidney Disease. Although existing immunochemical methods for their detection have provided compelling data, these approaches are indirect, lack specificity and are subject to a number of other technical and theoretical shortcomings. Here we have developed a rapid homogeneous fluorescent probe-based flow cytometric method for the detection and quantitation of individual mineral-containing nanoparticles in human and animal serum. This method allows the discrimination of membrane-bound from membrane-free particles and different mineral phases (amorphous vs. crystalline). Critically, the method has been optimised for use on a conventional instrument, without the need for manual hardware adjustments. Using this method, we demonstrate a consistency in findings across studies of Chronic Kidney Disease patients and commonly used uraemic animal models. These studies demonstrate that renal dysfunction is associated with the ripening of calciprotein particles to the crystalline state and reveal bone metabolism and dietary mineral as important modulators of circulating levels. Flow cytometric analysis of calciprotein particles may enhance our understanding of mineral handling in kidney disease and provide a novel indicator of therapeutic efficacy for interventions targeting Chronic Kidney Disease-Mineral Bone Disorder.
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Affiliation(s)
- Edward R Smith
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia. .,Department of Medicine - Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia.
| | - Tim D Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia.,Department of Medicine - Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Michael M X Cai
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia.,Department of Medicine - Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | | | - Matthias Bachtler
- Department of Clinical Research, University of Bern, Bern, Switzerland
| | - Andreas Pasch
- Department of Clinical Research, University of Bern, Bern, Switzerland
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia.,Department of Medicine - Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
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Tan SJ, Smith ER, Holt SG, Hewitson TD, Toussaint ND. Soluble klotho may be a marker of phosphate reabsorption. Clin Kidney J 2017; 10:397-404. [PMID: 28616218 PMCID: PMC5466110 DOI: 10.1093/ckj/sfw146] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 12/05/2016] [Indexed: 12/20/2022] Open
Abstract
Background: Membrane-bound α-klotho functions as a co-receptor with fibroblast growth factor receptor at the renal tubule conferring specificity to fibroblast growth factor-23 (FGF-23), allowing it to inhibit tubular phosphate reabsorption at physiological concentrations. α-klotho also exists as a soluble protein. However, the complex interrelationships between soluble α-klotho (sKl), FGF-23 and phosphate reabsorption are poorly understood, with little known about the links between sKl, FGF-23 and phosphate reabsorption in chronic kidney disease (CKD). This study addresses this issue in a cohort of patients with and without CKD. Methods: We conducted a single-centre, cross-sectional study of contemporaneously obtained samples of blood and 24-h urine biochemistry along with sKl and intact FGF-23 (iFGF-23) from non-dialysis-dependent CKD patients and healthy volunteers. Pearson's correlation coefficients were used to determine correlations between natural log-transformed (Ln) sKl and iFGF-23 with other parameters of interest. Backward multivariate analysis was undertaken to evaluate the relationship between mineral parameters. Results: One hundred and sixteen participants (77 with CKD and 39 healthy volunteers) were studied, of which 74 (63.8%) were male. The median age was 61 (interquartile range 49-71) years. Those with CKD had lower sKl (408 versus 542 pg/mL), higher iFGF-23 (94 versus 41 pg/mL), higher fractional excretion of phosphate (25.05 versus 10.98%) and lower daily urinary phosphate excretion (UPE) (24.8 versus 32.3 mmol/L) compared with healthy volunteers (all P ≤ 0.002). Age correlated inversely and estimated glomerular filtration rate (eGFR) correlated positively with phosphate reabsorption and Ln(sKl), while the opposite was seen with Ln(iFGF23). Upon multivariate analysis, eGFR, Ln(sKl) and parathyroid hormone were independently associated with phosphate reabsorption, whereas Ln(iFGF-23) was not, after adjustment for age. Conclusions: Abnormalities in phosphate regulatory pathways are disturbed early in CKD. While iFGF-23 is associated with phosphate excretion on univariate analyses, sKl demonstrates a significant association with phosphate reabsorption independent of iFGF-23, and this relationship deserves further exploration.
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Affiliation(s)
- Sven-Jean Tan
- Department of Nephrology, Royal Melbourne Hospital, Parkville, Australia
- Department of Medicine (RMH), University of Melbourne, Melbourne, Australia
| | - Edward R. Smith
- Department of Nephrology, Royal Melbourne Hospital, Parkville, Australia
| | - Stephen G. Holt
- Department of Nephrology, Royal Melbourne Hospital, Parkville, Australia
- Department of Medicine (RMH), University of Melbourne, Melbourne, Australia
| | - Tim D. Hewitson
- Department of Nephrology, Royal Melbourne Hospital, Parkville, Australia
- Department of Medicine (RMH), University of Melbourne, Melbourne, Australia
| | - Nigel D. Toussaint
- Department of Nephrology, Royal Melbourne Hospital, Parkville, Australia
- Department of Medicine (RMH), University of Melbourne, Melbourne, Australia
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Hewitson TD, Holt SG, Tan SJ, Wigg B, Samuel CS, Smith ER. Epigenetic Modifications to H3K9 in Renal Tubulointerstitial Cells after Unilateral Ureteric Obstruction and TGF-β1 Stimulation. Front Pharmacol 2017; 8:307. [PMID: 28611663 PMCID: PMC5447091 DOI: 10.3389/fphar.2017.00307] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 05/11/2017] [Indexed: 02/01/2023] Open
Abstract
Introduction: Epigenetic regulation of fibrogenesis through post-translational histone modifications (marks) may be a key determinant of progression in renal disease. In this study, we examined the distribution and acquisition of histone 3 Lysine 9 (H3K9) marks after injury and stimulation with the pro-fibrotic cytokine TGF-β1. Our focus was on their presence in activated fibroblasts (myofibroblasts) and epithelial cells (epithelial-mesenchymal transition). Methods and Results: Immunofluorescent microscopy was used to examine global H3K9 acetylation (H3K9Ac) and tri-methylation (H3K9Me3) after unilateral ureteric obstruction (UUO) in mice. Confocal, super resolution microscopy and flow cytometry were used to determine the in vitro effect of TGF-β1 on structural arrangement of these marks, and their relationship with α-smooth muscle actin (αSMA) expression, a marker of myofibroblasts and early EMT. The number of individual histone marks was increased 10 days after UUO (p < 0.05 vs. control), with both marks clearly seen in various cell types including proximal tubules and myofibroblasts. Sub-nuclear microscopy in primary rat renal fibroblasts and a proximal tubule cell line (NRK-52e) showed that H3K9Ac was co-localized with phosphorylated-Ser2 RNA polymerase II (pRNAPol II), while H3K9Me3 was not, consistent with permissive and repressive effects on gene expression respectively. In both cell types H3K9Ac was diffusely distributed throughout the nucleus, while H3K9Me3 was found in compartments resembling the nucleolus, and in the case of the fibroblast, also juxtapositioned with the nuclear membrane. TGF-β1 had no effect on H3K9Ac marks in either cell, but resulted in a redistribution of H3K9Me3 within the fibroblast nucleus. This was unrelated to any change in mitogenesis, but was associated with increased αSMA expression. Conclusion: These findings highlight why it is important to consider the epigenetics of each cell individually, because whilst no overall enrichment occurred, renal myofibroblast differentiation was accompanied by distinct changes in histone mark arrangements.
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Affiliation(s)
- Timothy D Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, MelbourneVIC, Australia.,Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, MelbourneVIC, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, MelbourneVIC, Australia.,Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, MelbourneVIC, Australia
| | - Sven-Jean Tan
- Department of Nephrology, The Royal Melbourne Hospital, MelbourneVIC, Australia
| | - Belinda Wigg
- Department of Nephrology, The Royal Melbourne Hospital, MelbourneVIC, Australia
| | - Chrishan S Samuel
- Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Pharmacology, Monash University, MelbourneVIC, Australia
| | - Edward R Smith
- Department of Nephrology, The Royal Melbourne Hospital, MelbourneVIC, Australia.,Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, MelbourneVIC, Australia
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Toussaint ND, Holt SG. Is serum phosphate a useful target in patients with chronic kidney disease and what is the role for dietary phosphate restriction? Nephrology (Carlton) 2017; 22 Suppl 2:36-41. [DOI: 10.1111/nep.13025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Nigel D Toussaint
- Department of Nephrology; The Royal Melbourne Hospital; Melbourne Parkville, Australia
- Department of Medicine; The University of Melbourne; Melbourne Australia
| | - Stephen G Holt
- Department of Nephrology; The Royal Melbourne Hospital; Melbourne Parkville, Australia
- Department of Medicine; The University of Melbourne; Melbourne Australia
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Hawley CM, Holt SG. Parathyroid hormone targets in chronic kidney disease and managing severe hyperparathyroidism. Nephrology (Carlton) 2017; 22 Suppl 2:47-50. [DOI: 10.1111/nep.13029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Carmel M Hawley
- Department Renal Medicine; Princess Alexandra Hospital; Brisbane Queensland Australia
- Department Renal Medicine; University of Queensland; Brisbane Queensland Australia
- Australasian Kidney Trials Network; University of Queensland; Brisbane Queensland Australia
- Translational Research Institute; Woolloongabba, Brisbane Queensland Australia
| | - Stephen G Holt
- Department Nephrology; The Royal Melbourne Hospital; Melbourne Victoria Australia
- Department of Medicine; The University of Melbourne; Melbourne Victoria Australia
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Tan SJ, Hewitson TD, Hughes PD, Holt SG, Toussaint ND. Changes in Markers of Mineral Metabolism After Living Kidney Donation. Transplant Direct 2017; 3:e150. [PMID: 28405606 PMCID: PMC5381743 DOI: 10.1097/txd.0000000000000660] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 01/27/2017] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Living kidney donors (LKDs) experience reduction in kidney function, however serum phosphate (sPi) levels are lower compared to patients with chronic kidney disease matched for reduced kidney function. Mineral metabolism adaptations that occur in LKDs have not been adequately investigated. To evaluate the effect of nephrectomy on markers of mineral metabolism in LKDs compared to healthy volunteers (HV) over 12 months. METHODS Mineral parameters were evaluated in twenty-one adult LKDs and twenty HVs. Parameters included sPi, intact parathyroid hormone, fibroblast growth factor-23 (FGF23), soluble Klotho (sKl) and urinary phosphate, measured prior to donation (T0), 1 month (T1), 6 months (T6) and 12 months (T12) post-kidney donation. Statistical analyses were conducted on normalized variables and changes were assessed using 2-way analysis of variance. RESULTS Mean ages of LKDs and HVs were 54.1 ± 14.7 and 52.6 ± 8.0 years, respectively. There were no baseline clinical or biochemical differences between LKDs and HVs. In LKDs at T1, serum creatinine increased (from 75 ± 12 to 114 ± 22 μmol/L), FGF23 increased (52 ± 15 to 70 ± 19 pg/mL) and sKl decreased (564 [469-662] to 424 [375-523] pg/mL), all P less than 0.001. Changes were sustained at T12. After donation, LKDs consistently demonstrated lower sPi compared with T0, with the maximal sPi change at T6 (-0.19 mmol/L difference, P < 0.001). Other markers of mineral metabolism were unchanged in LKDs. There were no mineral differences in HVs over 12 months. CONCLUSIONS Prospective evaluation of mineral metabolism parameters in LKDs provides valuable insight into compensatory mechanisms after reduction in kidney function. Further reduction of sPi at T6 despite early alterations in FGF23 and sKl suggest adaptation of mineral metabolism continues long-term in LKDs.
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Affiliation(s)
- Sven-Jean Tan
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia
- Department of Medicine (RMH), The University of Melbourne, Parkville, Victoria, Australia
| | - Tim D. Hewitson
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia
- Department of Medicine (RMH), The University of Melbourne, Parkville, Victoria, Australia
| | - Peter D. Hughes
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia
- Department of Medicine (RMH), The University of Melbourne, Parkville, Victoria, Australia
| | - Stephen G. Holt
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia
- Department of Medicine (RMH), The University of Melbourne, Parkville, Victoria, Australia
| | - Nigel D. Toussaint
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia
- Department of Medicine (RMH), The University of Melbourne, Parkville, Victoria, Australia
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Tan SJ, Satake S, Smith ER, Toussaint ND, Hewitson TD, Holt SG. Parenteral iron polymaltose changes i:c-terminal FGF23 ratios in iron deficiency, but not in dialysis patients. Eur J Clin Nutr 2016; 71:180-184. [DOI: 10.1038/ejcn.2016.217] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 09/22/2016] [Accepted: 09/27/2016] [Indexed: 12/17/2022]
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Toussaint ND, McMahon LP, Dowling G, Holt SG, Smith G, Safe M, Knight R, Fair K, Linehan L, Walker RG, Power DA. Introduction of Renal Key Performance Indicators Associated with Increased Uptake of Peritoneal Dialysis in a Publicly Funded Health Service. Perit Dial Int 2016; 37:198-204. [PMID: 27680765 DOI: 10.3747/pdi.2016.00149] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Accepted: 08/17/2016] [Indexed: 11/15/2022] Open
Abstract
♦ BACKGROUND: Increased demand for treatment of end-stage kidney disease has largely been accommodated by a costly increase in satellite hemodialysis (SHD) in most jurisdictions. In the Australian State of Victoria, a marked regional variation in the uptake of home-based dialysis suggests that use of home therapies could be increased as an alternative to SHD. An earlier strategy based solely on increased remuneration had failed to increase uptake of home therapies. Therefore, the public dialysis funder adopted the incidence and prevalence of home-based dialysis therapies as a key performance indicator (KPI) for its health services to encourage greater uptake of home therapies. ♦ METHODS: A KPI data collection and bench-marking program was established in 2012 by the Victorian Department of Health and Human Services, with data provided monthly by all renal units in Victoria using a purpose-designed website portal. A KPI Working Group was responsible for analyzing data each quarter and ensuring indicators remained accurate and relevant and each KPI had clear definitions and targets. We present a prospective, observational study of all dialysis patients in Victoria over a 4-year period following the introduction of the renal KPI program, with descriptive analyses to evaluate the proportion of patients using home therapies as well as home dialysis modality survival. ♦ RESULTS: Following the introduction of the KPI program, the net growth of dialysis patient numbers in Victoria remained stable over 4 years, at 75 - 80 per year (approximately 4%). However, unlike the previous decade, about 40% of this growth was through an increase in home dialysis, which was almost exclusively peritoneal dialysis (PD). The increase was identified particularly in the young (20 - 49) and the elderly (> 80). Disappointingly, however, 67% of these incident patients ceased PD within 2 years of commencement, 46% of whom transferred to SHD. ♦ CONCLUSIONS: Introduction of a KPI program was associated with an increased uptake of PD but not home HD. This change in clinical practice restricted growth of SHD and reduced pressure on satellite services. The effect was offset by a modest PD technique survival. Many patients in whom PD was unsuccessful were subsequently transferred to SHD rather than home HD.
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Affiliation(s)
- Nigel D Toussaint
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, VIC, Australia .,Department of Medicine, The University of Melbourne, Parkville, VIC, Australia
| | - Lawrence P McMahon
- Department of Renal Medicine, Eastern Health, Box Hill, VIC, Australia.,Eastern Health Clinical School, Monash University, Clayton, VIC, Australia
| | - Gregory Dowling
- Department of Health and Human Services, Melbourne, VIC, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, VIC, Australia.,Department of Medicine, The University of Melbourne, Parkville, VIC, Australia
| | - Gillian Smith
- Department of Health and Human Services, Melbourne, VIC, Australia
| | - Maria Safe
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, VIC, Australia
| | - Richard Knight
- Department of Renal Medicine, Barwon Health, Geelong, VIC, Australia
| | - Kathleen Fair
- Department of Nephrology, Bendigo Health, Bendigo, VIC, Australia
| | - Leanne Linehan
- Department of Nephrology, Monash Health, Clayton, VIC, Australia
| | - Rowan G Walker
- Department of Nephrology, Alfred Hospital, Prahran, VIC, Australia
| | - David A Power
- Department of Medicine, The University of Melbourne, Parkville, VIC, Australia.,Department of Nephrology, Austin Health, Heidelberg, VIC, Australia
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Abstract
Age-related changes in gastrointestinal symptoms need to be considered in peritoneal dialysis (PD) patients. A diminishing appetite is associated with aging and may be exacerbated by renal failure and PD treatment, meaning that attention to dietary adequacy is important in the older patient. Constipation and its treatment may increase the risk of peritonitis, but is important for comfort as well as trouble-free dialysis. Diverticulosis increases with age, and whilst there may be ethnic differences in the patterns of this condition, there is conflicting evidence regarding the risks of peritonitis associated with asymptomatic disease. Hernias, urinary incontinence, and prolapse are also common and made worse by PD, so it is important to know about these issues prior to starting. Whilst data around these topics are scant and some studies conflicting, further understanding these issues and considering mitigation strategies may improve technique survival and quality of life.
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Affiliation(s)
| | - Stephen G Holt
- Royal Melbourne Hospital, Melbourne, Australia The University of Melbourne, Melbourne, Australia
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Sharma AK, Masterson R, Holt SG, Tan SJ, Hughes PD, Chu M, Jayadeva P, Toussaint ND. Impact of cinacalcet pre-transplantation on mineral metabolism in renal transplant recipients. Nephrology (Carlton) 2016; 21:46-54. [PMID: 26072678 DOI: 10.1111/nep.12536] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/08/2015] [Indexed: 11/30/2022]
Abstract
AIM Cinacalcet is effective in reducing parathyroid hormone (PTH) in patients on dialysis. Reports of biochemical profiles and other clinical outcomes in patients discontinuing cinacalcet at time of renal transplantation are limited. METHODS A retrospective study assessing markers of mineral metabolism, graft and patient outcomes in renal transplant recipients to determine differences in patients discontinuing cinacalcet (C+) compared with patients not treated with cinacalcet (C-) at time of transplantation. To allow for differences between groups in pre-transplant biochemical parameters, we also analysed a matched cohort of C- with C+ recipients (2:1), matched for age, calcium and PTH levels at transplantation. RESULTS Five hundred thirty-two recipients (460 C-, 72 C+), transplanted January 2006-December 2012, were analysed, mean age 48.0 ± 12.7 years and 64.3% were men. At a median 42.9 months follow up, there were 10 deaths (1.9%), 56 allograft loss (10.6%) and 5 parathyroidectomies post-transplant (0.8%). Median PTH immediately pre-transplant was higher in C+ versus C- (50.7(25.4-75.2) versus 28.3(13.9-49.7) pmol/L, P < 0.001). Twelve-month post-transplant PTH was reduced but higher in C+ (11.7(6.9-21.2) vs 7.2(4.6-11.2) pmol/L, P < 0.001). Mean calcium was higher for C+ versus C- at 12 months (2.50 ± 0.19 vs 2.43 ± 0.17 mmol/L, P < 0.001), with differences to 4 years post-transplant. No difference was seen in renal function, graft loss, post-transplant parathyroidectomy rate and mortality. In the matched cohort (144 C- vs 72 C+), similar findings were also seen. CONCLUSION Differences in mineral metabolism post-transplant are seen with cinacalcet pre-transplant compared with no cinacalcet. Transplant recipients discontinuing cinacalcet had higher post-transplant PTH and calcium although the clinical significance is unclear.
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Affiliation(s)
- Ashish K Sharma
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Victoria, Australia
| | - Rosemary Masterson
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia
| | - Stephen G Holt
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Victoria, Australia
| | - Sven-Jean Tan
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Victoria, Australia
| | - Peter D Hughes
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia
| | - Melissa Chu
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia
| | - Pavithra Jayadeva
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia
| | - Nigel D Toussaint
- Department of Nephrology, The Royal Melbourne Hospital, Parkville, Australia.,Department of Medicine (RMH), The University of Melbourne, Melbourne, Victoria, Australia
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Abstract
In infective cases of peritoneal dialysis (PD) peritonitis, examination of the effluent fluid usually shows a predominance of neutrophils, and a bacterial organism is frequently isolated by culture. Where no organisms are identified, cases are often referred to as culture-negative 'peritonitis,' but non-infective causes for cloudy effluent are rare. We report the unusual finding of cloudy effluent as a presenting sign of recurrent lymphoma, diagnosed by cytological examination of the peritoneal effluent.
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Affiliation(s)
- Paul Viray
- The Royal Melbourne Hospital, Parkville, Victoria, Australia
| | | | - Stephen G Holt
- The Royal Melbourne Hospital, Parkville, Victoria, Australia Department of Medicine, The University of Melbourne, Parkville, Australia
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Wang AYM, Brimble KS, Brunier G, Holt SG, Jha V, Johnson DW, Kang SW, Kooman JP, Lambie M, McIntyre C, Mehrotra R, Pecoits-Filho R. ISPD Cardiovascular and Metabolic Guidelines in Adult Peritoneal Dialysis Patients Part II - Management of Various Cardiovascular Complications. Perit Dial Int 2016; 35:388-96. [PMID: 26228783 DOI: 10.3747/pdi.2014.00278] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Cardiovascular mortality has remained high in patients on peritoneal dialysis (PD) due to the high prevalence of various cardiovascular complications including coronary artery disease, left ventricular hypertrophy and dysfunction, heart failure, arrhythmia (especially atrial fibrillation), cerebrovascular disease, and peripheral arterial disease. In addition, nearly a quarter of PD patients develop sudden cardiac death as the terminal life event. Thus, it is essential to identify effective treatment that may lower cardiovascular mortality and improve survival of PD patients. The International Society for Peritoneal Dialysis (ISPD) commissioned a global workgroup in 2012 to formulate a series of recommendation statements regarding lifestyle modification, assessment and management of various cardiovascular risk factors, and management of the various cardiovascular complications to be published in 2 guideline documents. This publication forms the second part of the guideline documents and includes recommendation statements on the management of various cardiovascular complications in adult chronic PD patients. The documents are intended to serve as a global clinical practice guideline for clinicians who look after PD patients. We also define areas where evidence is clearly deficient and make suggestions for future research in each specific area.
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Affiliation(s)
| | - K Scott Brimble
- St. Joseph's Healthcare, McMaster University, Hamilton, Ontario, Canada
| | - Gillian Brunier
- Lawrence S. Bloomberg Faculty of Nursing, University of Toronto, Toronto, Ontario, Canada
| | - Stephen G Holt
- Division of Nephrology, The Royal Melbourne Hospital, University of Melbourne, Melbourne, Australia
| | - Vivekanand Jha
- George Institute for Global Health India, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - David W Johnson
- University of Queensland at Princess Alexandra Hospital, Brisbane, Australia Centre for Kidney Disease Research, Translational Research Institute, Brisbane, Australia
| | - Shin-Wook Kang
- Department of Internal Medicine, College of Medicine, Severance Biomedical Science Institute, Yonsei University, Korea
| | - Jeroen P Kooman
- Division of Nephrology, University Hospital Maastricht, Maastricht, The Netherlands
| | - Mark Lambie
- Health Services Research Unit, Institute for Science and Technology in Medicine, Keele University, Keele, Staffordshire, United Kingdom
| | - Chris McIntyre
- School of Medicine, University of Nottingham, Royal Derby Hospital Centre, Derby, United Kingdom
| | - Rajnish Mehrotra
- Harborview Medical Center, Division of Nephrology/Department of Medicine, University of Washington, Washington, DC, United States
| | - Roberto Pecoits-Filho
- School of Medicine, Pontifícia Universidade Católica do Paraná, Curitiba, Paraná, Brazil
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Tan SJ, Smith ER, Hewitson TD, Holt SG, Toussaint ND. The importance of klotho in phosphate metabolism and kidney disease. Nephrology (Carlton) 2016; 19:439-49. [PMID: 24750549 DOI: 10.1111/nep.12268] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/14/2014] [Indexed: 12/19/2022]
Abstract
The discovery of fibroblast growth factor-23 (FGF23) and its co-receptor α-klotho has broadened our understanding of mineral metabolism and led to a renewed research focus on phosphate homeostatic pathways in kidney disease. Expanding knowledge of these mechanisms, both in normal physiology and in pathology, identifies targets for potential interventions designed to reduce the complications of renal disease, particularly the cardiovascular sequelae. FGF23 has emerged as a major α-klotho-dependent endocrine regulator of mineral metabolism, functioning to activate vitamin D and as a phosphatonin. However, increasingly there is an appreciation that klotho may act independently as a phosphate regulator, as well as having significant activity in other key biological processes. This review outlines our current understanding of klotho, and its potential contribution to kidney disease and cardiovascular health.
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Affiliation(s)
- Sven-Jean Tan
- Department of Nephrology, The Royal Melbourne Hospital, Melbourne, Victoria, Australia; Department of Medicine (RMH), The University of Melbourne, Melbourne, Victoria, Australia
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Holt SG, Smith ER. Fetuin-A-containing calciprotein particles in mineral trafficking and vascular disease. Nephrol Dial Transplant 2016; 31:1583-7. [PMID: 27190332 DOI: 10.1093/ndt/gfw048] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 02/18/2016] [Indexed: 11/14/2022] Open
Abstract
Calcium and phosphate combine to form insoluble precipitates in both inorganic and organic materials. This property is useful biologically and has been used by numerous organisms to create hard tissues, a process referred to as biomineralisation [1]. In humans, calcium and phosphate combine to form useful crystal structures largely composed of calcium hydroxyapatite [Ca10(PO4)6(OH)2] and these are essential in the growth, maintenance and strength of parts of the skeleton and other structures like teeth. However, it remains unclear how the body achieves the exquisite specificity involved in biomineralisation. In ageing and disease, these pathways are perturbed, resulting in ectopic calcium crystal deposition impairing tissue function and, interestingly, frequently accompanied by simultaneous loss of mineral from sites where it is useful (e.g. bone). One paradigm for this maladaptive situation is renal failure; a situation that we know is associated with vascular stiffening and calcification, along with mineral loss from the skeleton. Mineral trafficking is a loose term used to describe the movements of calcium salts around the body, and new insights into these pathways may explain some of the problems of previous models of bone mineral disease in renal failure and point to potential future therapeutic strategies.
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Affiliation(s)
- Stephen G Holt
- Royal Melbourne Hospital, 300 Grattan Street, Parkville, Melbourne, VIC 3050, Australia Melbourne University, Melbourne Medical School, Level 2 (Street level), West Wing, Medical Building 181, Parkville, VIC 3050, Australia
| | - Edward R Smith
- Royal Melbourne Hospital, 300 Grattan Street, Parkville, Melbourne, VIC 3050, Australia
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