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Chow CM, Persad AH, Karnik R. Effect of Membrane Permeance and System Parameters on the Removal of Protein-Bound Uremic Toxins in Hemodialysis. Ann Biomed Eng 2024; 52:526-541. [PMID: 37993752 PMCID: PMC10859350 DOI: 10.1007/s10439-023-03397-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 10/25/2023] [Indexed: 11/24/2023]
Abstract
Inadequate clearance of protein-bound uremic toxins (PBUTs) during dialysis is associated with morbidities in chronic kidney disease patients. The development of high-permeance membranes made from materials such as graphene raises the question whether they could enable the design of dialyzers with improved PBUT clearance. Here, we develop device-level and multi-compartment (body) system-level models that account for PBUT-albumin binding (specifically indoxyl sulfate and p-cresyl sulfate) and diffusive and convective transport of toxins to investigate how the overall membrane permeance (or area) and system parameters including flow rates and ultrafiltration affect PBUT clearance in hemodialysis. Our simulation results indicate that, in contrast to urea clearance, PBUT clearance in current dialyzers is mass-transfer limited: Assuming that the membrane resistance is dominant, raising PBUT permeance from 3 × 10-6 to 10-5 m s-1 (or equivalently, 3.3 × increase in membrane area from ~ 2 to ~ 6 m2) increases PBUT removal by 48% (from 22 to 33%, i.e., ~ 0.15 to ~ 0.22 g per session), whereas increasing dialysate flow rates or adding adsorptive species have no substantial impact on PBUT removal unless permeance is above ~ 10-5 m s-1. Our results guide the future development of membranes, dialyzers, and operational parameters that could enhance PBUT clearance and improve patient outcomes.
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Affiliation(s)
- Chun Man Chow
- Department of Chemical Engineering, Massachusetts Institute of Technology, 25 Ames St, Cambridge, MA, 02142, USA
| | - Aaron H Persad
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139, USA
| | - Rohit Karnik
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA, 02139, USA.
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Meyer TW, Lee S, Whitmer LC, Blanco IJ, Suba JK, Sirich TL. Increasing the Clearance of Protein-Bound Solutes by Recirculating Dialysate through Activated Carbon. KIDNEY360 2023; 4:e744-e750. [PMID: 37211642 PMCID: PMC10371360 DOI: 10.34067/kid.0000000000000155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 04/05/2023] [Indexed: 05/23/2023]
Abstract
Key Points Conventional hemodialysis provides limited clearance of uremic solutes that bind to plasma proteins. No studies have yet tested whether increasing the clearance of bound solutes provides clinical benefit. Practical means to increase the dialytic clearance of bound solutes are required to perform such studies. Background Conventional hemodialysis provides limited clearance of uremic solutes that bind to plasma proteins. However, no studies have tested whether increasing the clearance of bound solutes provides clinical benefit. Practical means to increase the dialytic clearance of bound solutes are required to perform such studies. Methods Artificial plasma was dialyzed using two dialysis systems in series. In the first recirculating system, a fixed small volume of dialysate flowed rapidly through an activated carbon block before passing through two large dialyzers. In a second conventional system, a lower flow of fresh dialysate was passed through a single dialyzer. Chemical measurements tested the ability of the recirculating system to increase the clearance of selected solutes. Mathematical modeling predicted the dependence of solute clearances on the extent to which solutes were taken up by the carbon block and were bound to plasma proteins. Results By itself, the conventional system provided clearances of the tightly bound solutes p-cresol sulfate and indoxyl sulfate of only 18±10 and 19±11 ml/min, respectively (mean±SD). Because these solutes were effectively adsorbed by the carbon block, the recirculating system by itself provided p-cresol sulfate and indoxyl sulfate clearances of 45±11 and 53±16 ml/min. It further raised their clearances to 54±12 and 61±17 ml/min when operating in series with the conventional system (P < 0.002 versus conventional clearance both solutes). Modeling predicted that the recirculating system would increase the clearances of bound solute even if their uptake by the carbon block was incomplete. Conclusions When added to a conventional dialysis system, a recirculating system using a carbon block sorbent, a single pump, and standard dialyzers can greatly increase the clearance of protein-bound uremic solutes.
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Affiliation(s)
- Timothy W. Meyer
- The Department of Medicine, Stanford University, Palo Alto, California
- The Department of Medicine, VA Palo Alto Healthcare System, Palo Alto, California
| | - Seolhyun Lee
- The Department of Medicine, Stanford University, Palo Alto, California
- The Department of Medicine, VA Palo Alto Healthcare System, Palo Alto, California
| | - Luke C. Whitmer
- The Department of Medicine, Stanford University, Palo Alto, California
- The Department of Medicine, VA Palo Alto Healthcare System, Palo Alto, California
| | - Ignacio J. Blanco
- The Department of Medicine, Stanford University, Palo Alto, California
- The Department of Medicine, VA Palo Alto Healthcare System, Palo Alto, California
| | - Josef K. Suba
- The Department of Medicine, Stanford University, Palo Alto, California
- The Department of Medicine, VA Palo Alto Healthcare System, Palo Alto, California
| | - Tammy L. Sirich
- The Department of Medicine, Stanford University, Palo Alto, California
- The Department of Medicine, VA Palo Alto Healthcare System, Palo Alto, California
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Numerical modeling and parametric study of a hollow fiber dialyzer using double porous media approach. SOUTH AFRICAN JOURNAL OF CHEMICAL ENGINEERING 2022. [DOI: 10.1016/j.sajce.2022.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Determinants of Hemodialysis Performance: Modeling Fluid and Solute Transport in Hollow-Fiber Dialyzers. REGENERATIVE ENGINEERING AND TRANSLATIONAL MEDICINE 2021; 7:291-300. [PMID: 34926787 DOI: 10.1007/s40883-019-00135-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Hemodialysis constitutes the lifeline of patients with end stage renal disease, yet the parameters that affect hemodialyzer performance remain incompletely understood. We developed a computational model of mass transfer and solute transport in a hollow-fiber dialyzer to gain greater insight into the determinant factors. The model predicts fluid velocity, pressure, and solute concentration profiles for given geometric characteristics, membrane transport properties, and inlet conditions. We examined the impact of transport and structural parameters on uremic solute clearance by varying parameter values within the constraints of standard clinical practice. The model was validated by comparison with published experimental data. Our results suggest solute clearance can be significantly altered by changes in blood and dialysate flow rates, fiber radius and length, and net ultrafiltration rate. Our model further suggests that the main determinant of the clearance of unreactive solutes is their diffusive permeability. The clearance of protein-bound toxins is also strongly determined by blood hematocrit and plasma protein concentrations. Results from this model may serve to optimize hemodialyzer operating conditions in clinical practice to achieve better clearance of pathogenic uremic solutes.
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Shi Y, Tian H, Wang Y, Shen Y, Zhu Q, Ding F. Improved Dialysis Removal of Protein-Bound Uraemic Toxins with a Combined Displacement and Adsorption Technique. Blood Purif 2021; 51:548-558. [PMID: 34515053 DOI: 10.1159/000518065] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 06/04/2021] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Protein-bound uraemic toxins (PBUTs) are poorly removed by conventional dialytic techniques, given their high plasma protein binding, and thus low, free (dialysable) plasma concentration. Here, we evaluated and compared PBUTs removal among conventional haemodialysis (HD), adsorption-based HD, displacement-based HD, and their 2 combinations both in vitro and in vivo. METHODS The removal of PBUTs, including 3-carboxy-4-methyl-5-propyl-2-furan-propanoic acid (CMPF), p-cresyl sulphate (PCS), indoxyl sulphate (IS), indole-3-acetic acid (3-IAA), and hippuric acid, was first evaluated in an in vitro single-pass HD model. Adsorption consisted of adding 40 g/L bovine serum albumin (Alb) to the dialysate and displacement involved infusing fatty acid (FA) mixtures predialyser. Then, uraemic rats were treated with either conventional HD, Alb-based HD, lipid emulsion infusion-based HD or their combination to calculate the reduction ratio (RR), and the total solute removal (TSR) of solutes after 4 h of therapy. RESULTS In vitro dialysis revealed that FAs infusion prefilter increased the removal of PCS, IS, and 3-IAA 3.23-fold, 3.01-fold, and 2.24-fold, respectively, compared with baseline and increased the fractional removal of CMPF from undetectable at baseline to 14.33 ± 0.24%, with a dialysis efficacy markedly superior to Alb dialysis. In vivo dialysis showed that ω-6 soybean oil-based lipid emulsion administration resulted in higher RRs and more TSRs for PCS, IS, and 3-IAA after 4-h HD than the control, and the corresponding TSR values for PCS and IS were also significantly increased compared to that of Alb dialysis. Finally, the highest dialysis efficacy for highly bound solute removal was always observed with their combination both in vitro and in vivo. CONCLUSIONS The concept of combined displacement- and adsorption-based dialysis may open up new avenues and possibilities in the field of dialysis to further enhance PBUTs removal in end-stage renal disease.
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Affiliation(s)
- Yuanyuan Shi
- Department of Nephrology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China, .,Department of Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China,
| | - Huajun Tian
- Department of Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Yifeng Wang
- Department of Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Yue Shen
- Department of Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Qiuyu Zhu
- Department of Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Feng Ding
- Department of Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
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Synthesis of ceramic membrane using inexpensive precursors and evaluation of its biocompatibility for hemofiltration application. Sep Purif Technol 2021. [DOI: 10.1016/j.seppur.2020.117814] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Daneshamouz S, Eduok U, Abdelrasoul A, Shoker A. Protein-bound uremic toxins (PBUTs) in chronic kidney disease (CKD) patients: Production pathway, challenges and recent advances in renal PBUTs clearance. NANOIMPACT 2021; 21:100299. [PMID: 35559786 DOI: 10.1016/j.impact.2021.100299] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 01/13/2021] [Accepted: 01/20/2021] [Indexed: 06/15/2023]
Abstract
Uremic toxins, a group of uremic retention solutes with high concentration which their accumulation on the body makes several biological problems, have recently gained a large interest. The importance of this issue more targets patients with compromised kidney function since the presence of these toxins in their bodies contributes to serious illness and death. It is reported that around 14% of people are subjected of CKD's problems. Among different classifications of uremic toxins, protein bound uremic toxins are poorly removed from the body as they tightly bind to proteins like serum albumin. A deeper and closer understanding of methods for removing protein bound uremic toxins and their efficiency is of paramount importance. This article discussed the most critical protein bound uremic toxins from different points of view including their chemistry, binding sites, interactions, and their biological impacts. Concerning the toxicity and high concentration, p-cresyl sulfate (PCS), Indoxyl sulfate (IS), 3-Carboxy-4-methyl-5-propyl-2-furanpropionic acid (CMPF), and Indole- 3-acetic acid (IAA) was chosen to study in this article. Results offered that the functional groups of mentioned PBUTs and the way that they interact with the adsorbent play an important role in finding substances for removal of them. Furthermore, the development of nanoparticle (NPs) for promising biomedical purposes has been explored. However, there is still a need for further investigation to find biocompatible substances focusing on the removal of PBUTs. PBUTs are a unique class of uremic toxins whose renal clearance mechanisms and role in uremic pathophysiology are still unclear. This review outlines the biochemical aspects of PBUT/protein binding in a view to explaining their renal formation to elimination mechanisms; some examples are drawn from routes involving albumin-binding with indoxyl sulphate, p-cresyl sulfate, p-cresyl glucuronide and hippuric acid. We have also highlighted the kinetic behaviors during dialytic removal of PBUTs to address future concerns regarding dialytic therapy.
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Affiliation(s)
- Sana Daneshamouz
- Department of Chemical and Biological Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Saskatchewan S7N 5A9, Canada
| | - Ubong Eduok
- Department of Chemical and Biological Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Saskatchewan S7N 5A9, Canada
| | - Amira Abdelrasoul
- Department of Chemical and Biological Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Saskatchewan S7N 5A9, Canada; Department of Biomedical Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Saskatchewan S7N 5A9, Canada.
| | - Ahmed Shoker
- Nephrology Division, College of Medicine, University of Saskatchewan, 107 Wiggins Rd, Saskatoon, SK S7N 5E5, Canada; Saskatchewan Transplant Program, St. Paul's Hospital, 1702 20th Street West Saskatoon Saskatchewan S7M 0Z9, Canada
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Vandenbosch I, Dejongh S, Claes K, Bammens B, De Vusser K, Van Craenenbroeck A, Kuypers D, Evenepoel P, Meijers B. Strategies for asymmetrical triacetate dialyser heparin-free effective haemodialysis: the SAFE study. Clin Kidney J 2020; 14:1901-1907. [PMID: 34345413 PMCID: PMC8323132 DOI: 10.1093/ckj/sfaa228] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 09/18/2020] [Indexed: 11/30/2022] Open
Abstract
Background In haemodialysis, maintaining patency of the extracorporeal circuit requires the use of anticoagulants. Although (low molecular weight) heparins are the mainstay, these are not well tolerated in all patients. Alternative approaches include saline infusion, citrate-containing dialysate, regional citrate anticoagulation or the use of heparin-coated membranes. Asymmetric cellulose triacetate (ATA) dialysers have a low degree of platelet contact activation and might be an alternative to heparin-coated dialysers. The aim of this study was to test the clotting propensity of ATA when used without systemic anticoagulation. Methods We performed a Phase II pilot study in maintenance dialysis patients. The ‘Strategies for Asymmetrical Triacetate dialyzer heparin-Free Effective hemodialysis’ (SAFE) study was a two-arm open-label crossover study. In Arm A, patients were dialysed using 1.9 m2 ATA membranes in combination with a citrate-containing dialysate (1 mM). In Arm B, the ATA membrane was combined with high-volume predilution haemodiafiltration (HDF) without any other anticoagulation. The primary endpoint was the success rate to complete 4 h of haemodialysis without preterm clotting. Secondary endpoints included time to clotting and measures of dialysis adequacy. Results We scheduled 240 dialysis sessions (120/arm) in 20 patients. Patients were randomized 1:1 to start with Arm A or B. All patients crossed to the other arm halfway through the study. A total of 232 (96.7%) study treatments were delivered. Overall, 23 clotting events occurred, 7 in Arm A and 16 in Arm B. The success rate in Arm A (ATA + citrate-containing dialysate) was 90.8/94.0% [intention to treat (ITT)/as treated]. The success rate in Arm B (ATA + predilution HDF) was 83.3/86.2% (ITT/as treated). Time to clotting was borderline significantly better in Arm A (Mantel-Cox log rank P = 0.05). Conclusion ATA dialysers have a low clotting propensity and both predilution HDF and a citrate-containing dialysate resulted in high rates of completed dialysis sessions.
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Affiliation(s)
- Ines Vandenbosch
- Nephrology Unit, Ziekenhuizen Gasthuiszusters, Antwerpen, Belgium.,Division of Nephrology, UZ Leuven, Leuven, Belgium
| | - Sander Dejongh
- Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium
| | - Kathleen Claes
- Division of Nephrology, UZ Leuven, Leuven, Belgium.,Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium
| | - Bert Bammens
- Division of Nephrology, UZ Leuven, Leuven, Belgium.,Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium
| | - Katrien De Vusser
- Division of Nephrology, UZ Leuven, Leuven, Belgium.,Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium
| | - Amaryllis Van Craenenbroeck
- Division of Nephrology, UZ Leuven, Leuven, Belgium.,Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium
| | - Dirk Kuypers
- Division of Nephrology, UZ Leuven, Leuven, Belgium.,Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium
| | - Pieter Evenepoel
- Division of Nephrology, UZ Leuven, Leuven, Belgium.,Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium
| | - Björn Meijers
- Division of Nephrology, UZ Leuven, Leuven, Belgium.,Department of Microbiology and Immunology, KU Leuven, Leuven, Belgium
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Wang L, Xiang F, Ji J, Ding X, Shen B, Chen J, Chen Y, Xue N, Zhang L, Jiang X, Cao X. Indoxyl sulfate and high-density lipoprotein cholesterol in early stages of chronic kidney disease. Ren Fail 2020; 42:1157-1163. [PMID: 33191829 PMCID: PMC7671672 DOI: 10.1080/0886022x.2020.1845731] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Background High IS level has been demonstrated to be associated with vascular calcification and lymphocyte functional disorders, which are both risk factors of CVD. Low HDL-c level is a risk factor of CVD in CKD patients. This study was designed to explore the potential relationship between IS and HDL-c levels in early stages of CKD population. Methods Patients of CKD stage 1-3 were enrolled in this cross-sectional study. Correlations between HDL-c and IS levels were investigated among various clinicopathological variables through independent samples t test and multivariate logistic regression. Results A total of 205 CKD patients (96 men) aged 43.27 ± 13.80 years old were included in this research. There were 96 patients (46 men) in CKD stage1 and 109 (50 men) in CKD stage 2 or stage 3. IS levels were significantly higher in CKD 2 + 3 group (1.50 ± 1.74 μg/ml vs. 0.94 ± 0.66 μg/ml, p = 0.007), while HDL-c levels were lower (1.19 ± 0.39 mmol/L vs. 1.33 ± 0.45 mmol/L, p = 0.017) compared to CKD 1 group. Among all the patients, a negative correlation was observed between IS and HDL-c levels (r = −0.244, p = 0.001). IS level was an independent risk factor for low HDL-c (<1.04 mmol/L) incidence even after controlling for potential confounders including concomitant disease, age, sex, blood pressure, BMI and laboratory biochemical test including eGFR (OR = 1.63, 95% CI: 1.11–2.39, p = 0.013). IS and HDL-c were both risk factors for predicting CKD stage 3. Conclusions In early CKD stages, low HDL-c level is associated with increased IS levels, which may be an important contributor in the development of dyslipidemia in CKD patients.
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Affiliation(s)
- Li Wang
- Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China.,Shanghai Institute of Kidney and Dialysis, Shanghai, China.,Shanghai Key Laboratory of Kidney and Blood Purification, Shanghai, China
| | - Fangfang Xiang
- Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China.,Shanghai Institute of Kidney and Dialysis, Shanghai, China.,Shanghai Key Laboratory of Kidney and Blood Purification, Shanghai, China
| | - Jun Ji
- Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China.,Shanghai Institute of Kidney and Dialysis, Shanghai, China.,Shanghai Key Laboratory of Kidney and Blood Purification, Shanghai, China
| | - Xiaoqiang Ding
- Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China.,Shanghai Institute of Kidney and Dialysis, Shanghai, China.,Shanghai Key Laboratory of Kidney and Blood Purification, Shanghai, China
| | - Bo Shen
- Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China.,Shanghai Institute of Kidney and Dialysis, Shanghai, China.,Shanghai Key Laboratory of Kidney and Blood Purification, Shanghai, China
| | - Jing Chen
- Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China.,Shanghai Institute of Kidney and Dialysis, Shanghai, China.,Shanghai Key Laboratory of Kidney and Blood Purification, Shanghai, China
| | - Yunqin Chen
- Shanghai Institute of Cardiovascular Disease, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Ning Xue
- Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China.,Shanghai Institute of Kidney and Dialysis, Shanghai, China.,Shanghai Key Laboratory of Kidney and Blood Purification, Shanghai, China
| | - Lin Zhang
- Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China.,Shanghai Institute of Kidney and Dialysis, Shanghai, China.,Shanghai Key Laboratory of Kidney and Blood Purification, Shanghai, China
| | - Xiaotian Jiang
- Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China.,Shanghai Institute of Kidney and Dialysis, Shanghai, China.,Shanghai Key Laboratory of Kidney and Blood Purification, Shanghai, China
| | - Xuesen Cao
- Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China.,Shanghai Institute of Kidney and Dialysis, Shanghai, China.,Shanghai Key Laboratory of Kidney and Blood Purification, Shanghai, China
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Shi Y, Zhang Y, Tian H, Wang Y, Shen Y, Zhu Q, Ding F. Improved dialytic removal of protein-bound uremic toxins by intravenous lipid emulsion in chronic kidney disease rats. Nephrol Dial Transplant 2020; 34:1842-1852. [PMID: 31071223 DOI: 10.1093/ndt/gfz079] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Accepted: 03/22/2019] [Indexed: 01/30/2023] Open
Abstract
BACKGROUND Protein-bound uremic toxins (PBUTs) have received extensive attention, as their accumulation leads to pleiotropic toxic biological effects, while the removal of these solutes by conventional dialysis therapies is severely hampered. This study aimed to examine whether increased removal of PBUTs could be achieved with intravenous lipid emulsion (ILE). METHODS PBUTs such as 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (CMPF), p-cresyl sulfate (PCS) and indoxyl sulfate (IS) were spiked with human serum albumin (HSA) solution and the inhibitory effects of free fatty acid (FFA) on the binding of CMPF, PCS and IS to HSA were examined separately in vitro by ultrafiltration. In vitro dialysis of albumin solution was then performed to investigate the effects of fatty acid (FAs) mixtures infusion on the fractional removal of PBUTs. Finally, the inhibitory effect of FFA on the binding of PBUTs to albumin was examined in uremic rats, and blood purification therapy was conducted to calculate the reduction ratio (RR) and the total solute removal (TSR) of solutes. RESULTS The percentage protein binding of CMPF, PCS and IS decreased significantly with increasing FFAs concentrations, and the inhibitory effect was more remarkable with the addition of oleic acid or linoleic acid than that of eicosapentaenoic acid and docosahexaenoic acid. In vitro infusion of FAs increased the fractional removal of CMPF to 14.40 ± 2.38%. PCS, IS and indole-3-acetic acid removal increased from 8.00 ± 2.43%, 11.68 ± 1.54% and 15.38 ± 3.97%, respectively, at baseline to 28.21 ± 5.99%, 35.42 ± 5.27% and 40.18 ± 5.05%, respectively, when FAs were present. In vivo, rat serum concentrations of free PBUTs were significantly higher in the ILE group than in the control group, and administration of ILE resulted in higher RRs and more TSR for PBUTs after 3 h of hemodialysis (HD) therapy compared with the control group. CONCLUSIONS Administration of ILE effectively increased the dialytic removal of PBUTs. This method could be applied to current HD therapy.
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Affiliation(s)
- Yuanyuan Shi
- Division of Nephrology & Unit of Critical Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Yumei Zhang
- Division of Nephrology & Unit of Critical Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Huajun Tian
- Division of Nephrology & Unit of Critical Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Yifeng Wang
- Division of Nephrology & Unit of Critical Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Yue Shen
- Division of Nephrology & Unit of Critical Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Qiuyu Zhu
- Division of Nephrology & Unit of Critical Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Feng Ding
- Division of Nephrology & Unit of Critical Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
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Abstract
Dialyzer clearance of urea multiplied by dialysis time and normalized for urea distribution volume (Kt/Vurea or simply Kt/V) has been used as an index of dialysis adequacy since more than 30 years. This article reviews the flaws of Kt/V, starting with a lack of proof of concept in three randomized controlled hard outcome trials (RCTs), and continuing with a long list of conditions where the concept of Kt/V was shown to be flawed. This information leaves little room for any conclusion other than that Kt/V, as an indicator of dialysis adequacy, is obsolete. The dialysis patient might benefit more if, instead, the nephrology community concentrates in the future on pursuing the optimal dialysis dose that conforms with adequate quality of life and on factors that are likely to affect outcomes more than Kt/V. These include residual renal function, volume status, dialysis length, ultrafiltration rate, the number of intra-dialytic hypotensive episodes, interdialytic blood pressure, serum potassium and phosphate, serum albumin, and C reactive protein.
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Affiliation(s)
- Raymond Vanholder
- Nephrology Section, Department of Internal Medicine, University Hospital Ghent, Ghent, Belgium
| | - Wim Van Biesen
- Nephrology Section, Department of Internal Medicine, University Hospital Ghent, Ghent, Belgium
| | - Norbert Lameire
- Nephrology Section, Department of Internal Medicine, University Hospital Ghent, Ghent, Belgium
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12
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Shi Y, Wang Y, Ma S, Liu T, Tian H, Zhu Q, Wang W, Li Y, Ding F. Increasing the removal of protein-bound uremic toxins by liposome-supported hemodialysis. Artif Organs 2018; 43:490-503. [PMID: 30375673 DOI: 10.1111/aor.13383] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 10/13/2018] [Accepted: 10/17/2018] [Indexed: 12/14/2022]
Abstract
Protein-bound uremic toxins (PBUTs) accumulate at high plasma levels and cause various deleterious effects in end-stage renal disease patients because their removal by conventional hemodialysis is severely limited by their low free-fraction levels in plasma. Here, we assessed the extent to which solute removal can be increased by adding liposomes to the dialysate. The uptake of liposomes by direct incubation in vitro showed an obvious dose-response relationship for p-cresyl sulfate (PCS) and indoxyl sulfate (IS) but not for hippuric acid (HA). The percent removal of both PCS and IS but not of HA was gradually increased with the increased concentration of liposomes in a rapid equilibrium dialysis setup. In vitro closed circulation showed that adding liposomes to the dialysate markedly increased the dialysances of PBUTs without greatly altering that of urea and creatinine. In vivo experiments in uremic rats demonstrated that adding liposomes to the dialysate resulted in higher reduction ratios (RRs) and more total solute removal (TSR) for several PBUTs compared to the conventional dialysate, which was approximately similar to the addition of bovine serum albumin to the dialysate. These findings highlight that as an adjunct to conventional hemodialysis, addition of liposomes to the dialysate could significantly improve the removal of protein-bound uremic solutes without greatly altering the removal of small, water-soluble solutes.
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Affiliation(s)
- Yuanyuan Shi
- Division of Nephrology & Unit of Critical Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Yifeng Wang
- Division of Nephrology & Unit of Critical Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China.,The State Key Laboratory of Bioreactor Engineering, Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science & Technology, Shanghai, China
| | - Shuai Ma
- Division of Nephrology & Unit of Critical Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Tingyan Liu
- Division of Nephrology & Unit of Critical Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Huajun Tian
- Division of Nephrology & Unit of Critical Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Qiuyu Zhu
- Division of Nephrology & Unit of Critical Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Wenji Wang
- Division of Nephrology & Unit of Critical Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Yulin Li
- The State Key Laboratory of Bioreactor Engineering, Key Laboratory for Ultrafine Materials of Ministry of Education, East China University of Science & Technology, Shanghai, China
| | - Feng Ding
- Division of Nephrology & Unit of Critical Nephrology, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
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13
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Chevtchik NV, Mihajlovic M, Fedecostante M, Bolhuis-Versteeg L, Sastre Toraño J, Masereeuw R, Stamatialis D. A bioartificial kidney device with polarized secretion of immune modulators. J Tissue Eng Regen Med 2018; 12:1670-1678. [DOI: 10.1002/term.2694] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 04/04/2018] [Accepted: 05/03/2018] [Indexed: 12/24/2022]
Affiliation(s)
- N. V. Chevtchik
- Bioartificial Organs, Department of Biomaterials Science and Technology, MIRA Institute for Biomedical Technology and Technical Medicine; University of Twente; Enschede the Netherlands
| | - M. Mihajlovic
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences; Utrecht University; Utrecht the Netherlands
| | - M. Fedecostante
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences; Utrecht University; Utrecht the Netherlands
| | - L. Bolhuis-Versteeg
- Bioartificial Organs, Department of Biomaterials Science and Technology, MIRA Institute for Biomedical Technology and Technical Medicine; University of Twente; Enschede the Netherlands
| | - J. Sastre Toraño
- Division of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Sciences; Utrecht University; Utrecht the Netherlands
| | - R. Masereeuw
- Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences; Utrecht University; Utrecht the Netherlands
| | - D. Stamatialis
- Bioartificial Organs, Department of Biomaterials Science and Technology, MIRA Institute for Biomedical Technology and Technical Medicine; University of Twente; Enschede the Netherlands
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14
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Gong D, Cruz D, Ronco C. Depurative capacity of molecular adsorbent recycling system (MARS): A focus on bilirubin removal. Int J Artif Organs 2018; 31:875-81. [DOI: 10.1177/039139880803101003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The molecular adsorbent recycling system (MARS) is now widely used in the treatment of patients with hepatic failure (HF). A great deal of interest has been directed toward its effect on clinical outcome, whereas its depurative capacity also needs attention. Bilirubin, a tightly albumin-bound toxin accumulating in patients with HF, is regarded as a surrogate to evaluate the depurative capacity of albumin-bound toxins by blood purification modalities. The removal of bilirubin by MARS is difficult to predict, because both the clearance of bilirubin and the reduction ratio of bilirubin after a single session differ between patients and sessions. A reduction of depurative capacity over the course of a treatment is observed. Furthermore, the later sessions are likely less efficient than previous ones. It cannot be taken for granted that the reduction of depurative capacity is due to the saturation and reduced efficiency of the adsorbent columns used in MARS. The answer lies in the property of bilirubin/albumin binding. The removal of bilirubin by MARS is a diffusion process, dependent on the free bilirubin concentration. Bilirubin binds to albumin in 3 ways with different affinity. High-affinity binding bilirubin is difficult to dissociate from albumin and is accompanied by a smaller free fraction, which means it is also difficult for MARS to remove. The factors affecting the free fraction of bilirubin will impact on bilirubin removal by MARS. Among them, the molar ratio of bilirubin to albumin is the most important one. Other factors include the interaction of other agents with bilirubin/albumin binding, the albumin concentration, plasma ion strength, and pH.
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Affiliation(s)
- D. Gong
- Research Institute of Nephrology, Jingling Hospital, Nanjing University School of Medicine, Nanjing - PR China
| | - D. Cruz
- Department of Nephrology, Dialysis and Transplantation, San Bortolo Hospital, International Renal Research Institute Vicenza (IRRIV), Vicenza - Italy
| | - C. Ronco
- Department of Nephrology, Dialysis and Transplantation, San Bortolo Hospital, International Renal Research Institute Vicenza (IRRIV), Vicenza - Italy
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15
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Maheshwari V, Thijssen S, Tao X, Fuertinger D, Kappel F, Kotanko P. A novel mathematical model of protein-bound uremic toxin kinetics during hemodialysis. Sci Rep 2017; 7:10371. [PMID: 28871178 PMCID: PMC5583320 DOI: 10.1038/s41598-017-10981-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 08/10/2017] [Indexed: 11/17/2022] Open
Abstract
Protein-bound uremic toxins (PBUTs) are difficult to remove by conventional hemodialysis; a high degree of protein binding reduces the free fraction of toxins and decreases their diffusion across dialyzer membranes. Mechanistic understanding of PBUT kinetics can open new avenues to improve their dialytic removal. We developed a comprehensive model of PBUT kinetics that comprises: (1) a three-compartment patient model, (2) a dialyzer model. The model accounts for dynamic equilibrium between protein, toxin, and the protein-toxin complex. Calibrated and validated using clinical and experimental data from the literature, the model predicts key aspects of PBUT kinetics, including the free and bound concentration profiles for PBUTs and the effects of dialysate flow rate and dialyzer size on PBUT removal. Model simulations suggest that an increase in dialysate flow rate improves the reduction ratio (and removal) of strongly protein-bound toxins, namely, indoxyl sulfate and p-cresyl sulfate, while for weakly bound toxins, namely, indole-3-acetic acid and p-cresyl glucuronide, an increase in blood flow rate is advantageous. With improved dialyzer performance, removal of strongly bound PBUTs improves gradually, but marginally. The proposed model can be used for optimizing the dialysis regimen and for in silico testing of novel approaches to enhance removal of PBUTs.
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Affiliation(s)
| | | | - Xia Tao
- Renal Research Institute, New York, USA
| | | | - Franz Kappel
- Institute for Mathematics and Scientific Computing, University of Graz, Graz, Austria
| | - Peter Kotanko
- Renal Research Institute, New York, USA.,Icahn School of Medicine at Mount Sinai, New York, USA
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16
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Zhang A, Rijal K, Ng SK, Ravid K, Chitalia V. A mass spectrometric method for quantification of tryptophan-derived uremic solutes in human serum. J Biol Methods 2017; 4. [PMID: 29707597 PMCID: PMC5914531 DOI: 10.14440/jbm.2017.182] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
In addition to various physiologic roles, emerging evidence strongly points to pathogenic roles of tryptophan and of its metabolites, especially in diseases such as renal failure. Accurate estimation of levels of these metabolites in blood is important to mechanistically probe their contribution to disease pathogenesis, while clinically, such a panel can be used to risk stratify patients for a clinical phenotype. Herein, we describe a comprehensive liquid chromatography-mass spectrometry (LC/MS)-based method to determine the level of tryptophan and its metabolites (kynurenine, kynurenic acid, xanthurenic acid, anthranilic acid, indoxyl sulfate and indoxyl acetate). Human sera samples were processed through a C18 column followed by application of a binary gradient and quantitation by MS/MS. The linearity, lower limit of detection, inter- and intraassay variabilities and recovery were determined, yielding a precise, reproducible method for all the metabolites. Unlike previous studies, we further validated these methods in a well-characterized set of human sera from end stage renal disease patients compared to age-, gender- and ethnic-background matched human controls. Overall, we report an optimized LC/MS-based estimation of a comprehensive panel of tryptophan-derived metabolites with quality features within FDA standards, underscoring their readiness for translational use.
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Affiliation(s)
- Anqi Zhang
- Metabolomics Core, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Keshab Rijal
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Seng Kah Ng
- Whitaker Cardiovascular Institute and the Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Katya Ravid
- Whitaker Cardiovascular Institute and the Department of Medicine, Boston University School of Medicine, Boston, MA, USA
| | - Vipul Chitalia
- Renal Section, Department of Medicine, Boston University School of Medicine, Boston, MA, USA.,Whitaker Cardiovascular Institute and the Department of Medicine, Boston University School of Medicine, Boston, MA, USA
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17
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Sirich TL. Obstacles to reducing plasma levels of uremic solutes by hemodialysis. Semin Dial 2017; 30:403-408. [DOI: 10.1111/sdi.12609] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Tammy L. Sirich
- The Department of Medicine; VA Palo Alto Health Care System and Stanford University; Palo Alto CA USA
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18
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Krieter DH, Devine E, Körner T, Rüth M, Wanner C, Raine M, Jankowski J, Lemke HD. Haemodiafiltration at increased plasma ionic strength for improved protein-bound toxin removal. Acta Physiol (Oxf) 2017; 219:510-520. [PMID: 27259463 DOI: 10.1111/apha.12730] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 03/01/2016] [Accepted: 05/31/2016] [Indexed: 11/27/2022]
Abstract
AIM Protein-bound uraemic toxin accumulation causes uraemia-associated cardiovascular morbidity. Enhancing the plasma ionic strength releases toxins from protein binding and makes them available for removal during dialysis. This concept was implemented through high sodium concentrations ([Na+ ]) in the substituate of pre-dilution haemodiafiltration at increased plasma ionic strength (HDF-IPIS). METHODS Ex vivo HDF-IPIS with blood tested increasing [Na+ ] to demonstrate efficacy and haemocompatibility. Haemocompatibility was further assessed in sheep using two different HDF-IPIS set-ups and [Na+ ] between 350 and 600 mmol L-1 . Safety and efficacy of para-cresyl sulphate (pCS) and indoxyl sulphate (IS) removal was further investigated in a randomized clinical pilot trial comparing HDF-IPIS to HD and HDF. RESULTS Compared to [Na+ ] of 150 mmol L-1 , ex vivo HDF-IPIS at 500 mmol L-1 demonstrated up to 50% higher IS removal. Haemolysis in sheep was low even at [Na+ ] of 600 mmol L-1 (free Hb 0.016 ± 0.001 g dL-1 ). In patients, compared to HD, a [Na+ ] of 240 mmol L-1 in HDF-IPIS resulted in 40% greater reduction (48.7 ± 23.6 vs. 67.8 ± 7.9%; P = 0.013) in free IS. Compared to HD and HDF (23.0 ± 14.8 and 25.4 ± 10.5 mL min-1 ), the dialytic clearance of free IS was 31.6 ± 12.8 mL min-1 (P = 0.017) in HDF-IPIS, but [Na+ ] in arterial blood increased from 132 ± 2 to 136 ± 3 mmol L-1 (0 vs. 240 min; P < 0.001). CONCLUSION HDF-IPIS is technically and clinically feasible. More effective HDF-IPIS requires higher temporary plasma [Na+ ], but dialysate [Na+ ] has to be appropriately adapted to avoid sodium accumulation.
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Affiliation(s)
- D. H. Krieter
- Division of Nephrology; Department of Medicine; University Hospital Würzburg; Würzburg Germany
| | | | - T. Körner
- Division of Nephrology; Department of Medicine; University Hospital Würzburg; Würzburg Germany
| | - M. Rüth
- eXcorLab GmbH; Obernburg Germany
| | - C. Wanner
- Division of Nephrology; Department of Medicine; University Hospital Würzburg; Würzburg Germany
| | - M. Raine
- eXcorLab GmbH; Obernburg Germany
| | - J. Jankowski
- Institute of Molecular Cardiovascular Research; University Hospital RWTH Aachen; Aachen Germany
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19
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Leypoldt JK, Meijers BKI. Effect of Treatment Duration and Frequency on Uremic Solute Kinetics, Clearances and Concentrations. Semin Dial 2016; 29:463-470. [PMID: 27578429 DOI: 10.1111/sdi.12531] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The kinetics of uremic solute clearances are discussed based on two categories of uremic solutes, namely those that are and those that are not derived directly from nutrient intake, particularly dietary protein intake. This review highlights dialysis treatments that are more frequent and longer (high-dose hemodialysis) than conventional thrice weekly therapy. It is proposed that the dialysis dose measures based on urea as a marker uremic solute, such as Kt/V and stdKt/V, be referred to as measures of dialysis inadequacy, not dialysis adequacy. For uremic solutes derived directly from nutrient intake, it is suggested that inorganic phosphorus and protein-bound uremic solutes be considered as markers in the development of alternative measures of dialysis dose for high-dose hemodialysis prescriptions. As the current gap in understanding the detailed kinetics of protein-bound uremic solutes, it is proposed that normalization of serum phosphorus concentration with a minimum (or preferably without a) need for oral-phosphorus binders be targeted as a measure of dialysis adequacy in high-dose hemodialysis. For large uremic solutes not derived directly from nutrient intake (middle molecules), use of extracorporeal clearances for β2 -microglobulin that are higher than currently available during thrice weekly therapy is unlikely to reduce predialysis serum β2 -microglobulin concentrations. High-dose hemodialysis prescriptions will lead to reductions in predialysis serum β2 -microglobulin concentrations, but such reductions are also limited by significant residual kidney clearance. Kinetic data regarding middle molecules larger than β2 -microglobulin are scarce; additional studies on such uremic solutes are of high interest to better understand improved methods for prescribing high-dose hemodialysis prescriptions to improve patient outcomes.
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Affiliation(s)
- John K Leypoldt
- Renal Therapeutic Area and Medical Affairs, Baxter Healthcare Corporation, Deerfield, Illinois.
| | - Björn K I Meijers
- Division of Nephrology, Department of Microbiology and Immunology, University Hospitals Leuven, Leuven, Belgium
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20
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Chevtchik NV, Fedecostante M, Jansen J, Mihajlovic M, Wilmer M, Rüth M, Masereeuw R, Stamatialis D. Upscaling of a living membrane for bioartificial kidney device. Eur J Pharmacol 2016; 790:28-35. [PMID: 27395800 DOI: 10.1016/j.ejphar.2016.07.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 06/24/2016] [Accepted: 07/06/2016] [Indexed: 12/01/2022]
Abstract
The limited removal of metabolic waste products in dialyzed kidney patients leads to high morbidity and mortality. One powerful solution for a more complete removal of those metabolites might be offered by a bioartificial kidney device (BAK), which contains a hybrid "living membrane" with functional proximal tubule epithelial cells (PTEC). These cells are supported by an artificial functionalized hollow fiber membrane (HFM) and are able to actively remove the waste products. In our earlier studies, conditionally immortalized human PTEC (ciPTEC) showed to express functional organic cationic transporter 2 (OCT2) when seeded on small size flat or hollow fiber polyethersulfone (PES) membranes. Here, an upscaled "living membrane" is presented. We developed and assessed the functionality of modules containing three commercially available MicroPES HFM supporting ciPTEC. The HFM were optimally coated with L-Dopa and collagen IV to support a uniform and tight monolayer formation of matured ciPTEC under static culturing conditions. Both abundant expression of zonula occludens-1 (ZO-1) protein and limited diffusion of FITC-inulin confirm a clear barrier function of the monolayer. Furthermore, the uptake of 4-(4-(dimethylamino)styryl)-N-methylpyridinium iodide (ASP+), a fluorescent OCT2 substrate, was studied in absence and presence of known OCT inhibitors, such as cimetidine and a cationic uremic solutes mixture. The ASP+ uptake by the living upscaled membrane was decreased by 60% in the presence of either inhibitor, proving the active function of OCT2. In conclusion, this study presents a successful upscaling of a living membrane with active organic cation transport as a support for BAK device.
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Affiliation(s)
- Natalia Vladimirovna Chevtchik
- Department of Biomaterials Science and Technology, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands
| | - Michele Fedecostante
- Department of Pharmaceutical Sciences, UIPS Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Jitske Jansen
- Department of Pharmaceutical Sciences, UIPS Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Milos Mihajlovic
- Department of Pharmaceutical Sciences, UIPS Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Martijn Wilmer
- Department of Pharmacology and Toxicology, Radboud Institute for Molecular Life Sciences, Radboudumc, Nijmegen, The Netherlands
| | - Marieke Rüth
- eXcorLab GmbH, Industrie Center Obernburg, Obernburg, Germany
| | - Rosalinde Masereeuw
- Department of Pharmaceutical Sciences, UIPS Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands
| | - Dimitrios Stamatialis
- Department of Biomaterials Science and Technology, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands.
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21
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Protein-Bound Uremic Toxin Profiling as a Tool to Optimize Hemodialysis. PLoS One 2016; 11:e0147159. [PMID: 26799394 PMCID: PMC4723122 DOI: 10.1371/journal.pone.0147159] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 12/29/2015] [Indexed: 12/20/2022] Open
Abstract
Aim We studied various hemodialysis strategies for the removal of protein-bound solutes, which are associated with cardiovascular damage. Methods This study included 10 patients on standard (3x4h/week) high-flux hemodialysis. Blood was collected at the dialyzer inlet and outlet at several time points during a midweek session. Total and free concentration of several protein-bound solutes was determined as well as urea concentration. Per solute, a two-compartment kinetic model was fitted to the measured concentrations, estimating plasmatic volume (V1), total distribution volume (Vtot) and intercompartment clearance (K21). This calibrated model was then used to calculate which hemodialysis strategy offers optimal removal. Our own in vivo data, with the strategy variables entered into the mathematical simulations, was then validated against independent data from two other clinical studies. Results Dialyzer clearance K, V1 and Vtot correlated inversely with percentage of protein binding. All Ks were different from each other. Of all protein-bound solutes, K21was 2.7–5.3 times lower than that of urea. Longer and/or more frequent dialysis that processed the same amount of blood per week as standard 3x4h dialysis at 300mL/min blood flow showed no difference in removal of strongly bound solutes. However, longer and/or more frequent dialysis strategies that processed more blood per week than standard dialysis were markedly more adequate. These conclusions were successfully validated. Conclusion When blood and dialysate flow per unit of time and type of hemodialyzer are kept the same, increasing the amount of processed blood per week by increasing frequency and/or duration of the sessions distinctly increases removal.
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22
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Daugirdas JT. Lower cardiovascular mortality with high-volume hemodiafiltration: a cool effect? Nephrol Dial Transplant 2015; 31:853-6. [PMID: 26687900 DOI: 10.1093/ndt/gfv412] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 11/10/2015] [Indexed: 11/12/2022] Open
Affiliation(s)
- John T Daugirdas
- Medicine/Nephrology, University of Illinois at Chicago, Chicago, IL, USA
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23
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Suchy-Dicey AM, Laha T, Hoofnagle A, Newitt R, Sirich TL, Meyer TW, Thummel KE, Yanez ND, Himmelfarb J, Weiss NS, Kestenbaum BR. Tubular Secretion in CKD. J Am Soc Nephrol 2015; 27:2148-55. [PMID: 26614381 DOI: 10.1681/asn.2014121193] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 10/15/2015] [Indexed: 11/03/2022] Open
Abstract
Renal function generally is assessed by measurement of GFR and urinary albumin excretion. Other intrinsic kidney functions, such as proximal tubular secretion, typically are not quantified. Tubular secretion of solutes is more efficient than glomerular filtration and a major mechanism for renal drug elimination, suggesting important clinical consequences of secretion dysfunction. Measuring tubular secretion as an independent marker of kidney function may provide insight into kidney disease etiology and improve prediction of adverse outcomes. We estimated secretion function by measuring secreted solute (hippurate, cinnamoylglycine, p-cresol sulfate, and indoxyl sulfate) clearance using liquid chromatography-tandem mass spectrometric assays of serum and timed urine samples in a prospective cohort study of 298 patients with kidney disease. We estimated GFR by mean clearance of creatinine and urea from the same samples and evaluated associations of renal secretion with participant characteristics, mortality, and CKD progression to dialysis. Tubular secretion rate modestly correlated with eGFR and associated with some participant characteristics, notably fractional excretion of electrolytes. Low clearance of hippurate or p-cresol sulfate associated with greater risk of death independent of eGFR (hazard ratio, 2.3; 95% confidence interval, 1.1 to 4.7; hazard ratio, 2.5; 95% confidence interval, 1.0 to 6.1, respectively). Hazards models also suggested an association between low cinnamoylglycine clearance and risk of dialysis, but statistical analyses did not exclude the null hypothesis. Therefore, estimates of proximal tubular secretion function correlate with glomerular filtration, but substantial variability in net secretion remains. The observed associations of net secretion with mortality and progression of CKD require confirmation.
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Affiliation(s)
| | | | | | - Rick Newitt
- Kidney Research Institute, School of Medicine
| | - Tammy L Sirich
- School of Medicine, Stanford University, Stanford, California
| | - Timothy W Meyer
- School of Medicine, Stanford University, Stanford, California
| | - Ken E Thummel
- Department of Pharmaceutics, School of Pharmacy, University of Washington, Seattle, Washington; and
| | | | | | | | - Bryan R Kestenbaum
- Departments of Epidemiology and Kidney Research Institute, School of Medicine
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24
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Cheungpasitporn W, Zand L, Dillon JJ, Qian Q, Leung N. Lactate clearance and metabolic aspects of continuous high-volume hemofiltration. Clin Kidney J 2015; 8:374-7. [PMID: 26251702 PMCID: PMC4515900 DOI: 10.1093/ckj/sfv045] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 05/18/2015] [Accepted: 05/19/2015] [Indexed: 11/12/2022] Open
Abstract
Lactic acidosis is associated with high morbidity and mortality in hospitalized patients. Treatment of lactic acidosis is targeted on correcting the underlying causes and optimizing adequate oxygen delivery to the tissues. Even though evidence is lacking, continuous renal replacement therapy (CRRT) and dialysis have been advocated as treatments for lactic acidosis. We report a 28-year-old Caucasian male with a history of hemophagocytic lymphohistiocytosis who presented with septic shock, severe lactic acidosis and multiple organ failure. Metabolic acidosis was corrected after bicarbonate therapy and CRRT with a hemofiltration rate of 7 L/h (58 mL/kg/h). Lactate clearance was calculated to be 79 mL/min. Compared with reported rates of lactate overproduction in septic shock, the rate of lactate clearance is quite small. Our case suggests that CRRT with high-volume hemofiltration is not effective for severe lactic acidosis. Lactic acidosis alone should not be considered as a nonrenal indication for CRRT.
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Affiliation(s)
| | - Ladan Zand
- Division of Nephrology and Hypertension , Mayo Clinic , Rochester, MN , USA
| | - John J Dillon
- Division of Nephrology and Hypertension , Mayo Clinic , Rochester, MN , USA
| | - Qi Qian
- Division of Nephrology and Hypertension , Mayo Clinic , Rochester, MN , USA
| | - Nelson Leung
- Division of Nephrology and Hypertension , Mayo Clinic , Rochester, MN , USA ; Division of Hematology , Mayo Clinic , Rochester, MN , USA
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25
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Schophuizen CM, De Napoli IE, Jansen J, Teixeira S, Wilmer MJ, Hoenderop JG, Van den Heuvel LP, Masereeuw R, Stamatialis D. Development of a living membrane comprising a functional human renal proximal tubule cell monolayer on polyethersulfone polymeric membrane. Acta Biomater 2015; 14:22-32. [PMID: 25527093 DOI: 10.1016/j.actbio.2014.12.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 11/22/2014] [Accepted: 12/02/2014] [Indexed: 10/24/2022]
Abstract
The need for improved renal replacement therapies has stimulated innovative research for the development of a cell-based renal assist device. A key requirement for such a device is the formation of a "living membrane", consisting of a tight kidney cell monolayer with preserved functional organic ion transporters on a suitable artificial membrane surface. In this work, we applied a unique conditionally immortalized proximal tubule epithelial cell (ciPTEC) line with an optimized coating strategy on polyethersulfone (PES) membranes to develop a living membrane with a functional proximal tubule epithelial cell layer. PES membranes were coated with combinations of 3,4-dihydroxy-l-phenylalanine and human collagen IV (Coll IV). The optimal coating time and concentrations were determined to achieve retention of vital blood components while preserving high water transport and optimal ciPTEC adhesion. The ciPTEC monolayers obtained were examined through immunocytochemistry to detect zona occludens 1 tight junction proteins. Reproducible monolayers were formed when using a combination of 2 mg ml(-1) 3,4-dihydroxy-l-phenylalanine (4 min coating, 1h dissolution) and 25 μg ml(-1) Coll IV (4 min coating). The successful transport of (14)C-creatinine through the developed living membrane system was used as an indication for organic cation transporter functionality. The addition of metformin or cimetidine significantly reduced the creatinine transepithelial flux, indicating active creatinine uptake in ciPTECs, most likely mediated by the organic cation transporter, OCT2 (SLC22A2). In conclusion, this study shows the successful development of a living membrane consisting of a reproducible ciPTEC monolayer on PES membranes, an important step towards the development of a bioartificial kidney.
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Albumin dialysis in artificial liver support systems: open-loop or closed-loop dialysis mode? ASAIO J 2015; 61:324-31. [PMID: 25650810 DOI: 10.1097/mat.0000000000000198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
In artificial liver support systems, the open-loop albumin dialysis mode (OLM) is usually used to remove protein-bound toxins from the blood of patients with liver failure. However, there is still interest in the closed-loop albumin dialysis mode (CLM) because this mode may enable not only the regeneration and reuse of albumin but also the miniaturization of artificial liver systems. In this article, we compared the two modes under a fixed amount of albumin in dialysate experimentally and theoretically. The results show that according to the detoxification efficiency in the 3 hour dialysis for removing albumin-bound bilirubin, CLM is better than OLM. The usage efficiency of albumin in CLM is also higher. Moreover, the advantage of CLM is more significant when the concentration of bilirubin in blood is lower. Under a given amount of albumin in dialysate, if the concentration of bilirubin in blood is high, one may further increase the performance of CLM by means of increasing the flow rate of the albumin dialysate or using the highly concentrated albumin dialysate.
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Demirjian S, Fissell WH. Staying on target with continuous dialysis. Clin J Am Soc Nephrol 2015; 10:7-8. [PMID: 25538268 DOI: 10.2215/cjn.11251114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Sevag Demirjian
- Department of Nephrology and Hypertension, Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, Ohio; and
| | - William H Fissell
- Department of Nephrology and Hypertension, Vanderbilt University, Nashville, Tennessee
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Cao XS, Chen J, Zou JZ, Zhong YH, Teng J, Ji J, Chen ZW, Liu ZH, Shen B, Nie YX, Lv WL, Xiang FF, Tan X, Ding XQ. Association of indoxyl sulfate with heart failure among patients on hemodialysis. Clin J Am Soc Nephrol 2014; 10:111-9. [PMID: 25332316 DOI: 10.2215/cjn.04730514] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND AND OBJECTIVES Indoxyl sulfate, a protein-bound uremic toxin, may be associated with cardiovascular events and mortality in patients with CKD. This study aimed to investigate the relationship between indoxyl sulfate and heart failure in patients on hemodialysis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Patients on hemodialysis for >6 months were enrolled within 6 months. Patients with congestive heart failure, angina pectoris, acute myocardial infarction, cerebral infarction, or cerebral hemorrhage within 3 months before the study or those <18 years old were excluded. The primary end point was first heart failure event during follow-up. RESULTS In total, 258 patients (145 men) with a mean age of 57.0 ± 14.6 years old were enrolled. Median plasma indoxyl sulfate level was used to categorize patients into two groups: the low-indoxyl sulfate group (indoxyl sulfate ≤ 2.35 μg/ml) and the high-indoxyl sulfate group (indoxyl sulfate >32.35 μg/ml). Then, patients were prospectively followed up for a median of 48.0 (interquartile range: 33.5-48.0) months. During follow-up, 68 patients experienced episodes of first heart failure. Kaplan-Meier analysis revealed the incidence of first heart failure event in the high-indoxyl sulfate group was significantly higher than in the low-indoxyl sulfate group (log rank P<0.001). Cox regression analysis showed indoxyl sulfate was significantly associated with first heart failure event (indoxyl sulfate as the continuous variable: hazard ratio, 1.02; 95% confidence interval [95% CI], 1.01 to 1.03; P=0.001; indoxyl sulfate as the dichotomous variable: hazard ratio, 3.49; 95% CI, 1.97 to 6.20; P<0.001). After adjustment for other confounding factors, the results remained significant (indoxyl sulfate as the continuous variable: hazard ratio, 1.04; 95% CI, 1.02 to 1.06; P<0.001; indoxyl sulfate as the dichotomous variable: hazard ratio, 5.31; 95% CI, 2.43 to 11.58; P<0.001). CONCLUSIONS Plasma indoxyl sulfate was associated with first heart failure event in patients on hemodialysis. Whether indoxyl sulfate is only a biomarker or involved in the pathogenesis of heart failure in hemodialysis warrants additional study.
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Affiliation(s)
- Xue-Sen Cao
- Department of Nephrology, Shanghai Institute of Kidney and Dialysis, Shanghai Key Laboratory of Kidney and Blood Purification, Zhongshan Hospital
| | - Jun Chen
- Department of Pharmaceutics, School of Pharmacy; and
| | - Jian-Zhou Zou
- Department of Nephrology, Shanghai Institute of Kidney and Dialysis, Shanghai Key Laboratory of Kidney and Blood Purification, Zhongshan Hospital
| | - Yi-Hong Zhong
- Department of Nephrology, Shanghai Institute of Kidney and Dialysis, Shanghai Key Laboratory of Kidney and Blood Purification, Zhongshan Hospital
| | - Jie Teng
- Department of Nephrology, Shanghai Institute of Kidney and Dialysis, Shanghai Key Laboratory of Kidney and Blood Purification, Zhongshan Hospital
| | - Jun Ji
- Department of Nephrology, Shanghai Institute of Kidney and Dialysis, Shanghai Key Laboratory of Kidney and Blood Purification, Zhongshan Hospital
| | - Zhang-Wei Chen
- Department of Cardiology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Zhong-Hua Liu
- Department of Nephrology, Shanghai Institute of Kidney and Dialysis, Shanghai Key Laboratory of Kidney and Blood Purification, Zhongshan Hospital
| | - Bo Shen
- Department of Nephrology, Shanghai Institute of Kidney and Dialysis, Shanghai Key Laboratory of Kidney and Blood Purification, Zhongshan Hospital
| | - Yu-Xin Nie
- Department of Nephrology, Shanghai Institute of Kidney and Dialysis, Shanghai Key Laboratory of Kidney and Blood Purification, Zhongshan Hospital
| | - Wen-Lv Lv
- Department of Nephrology, Shanghai Institute of Kidney and Dialysis, Shanghai Key Laboratory of Kidney and Blood Purification, Zhongshan Hospital
| | - Fang-Fang Xiang
- Department of Nephrology, Shanghai Institute of Kidney and Dialysis, Shanghai Key Laboratory of Kidney and Blood Purification, Zhongshan Hospital
| | - Xiao Tan
- Department of Nephrology, Shanghai Institute of Kidney and Dialysis, Shanghai Key Laboratory of Kidney and Blood Purification, Zhongshan Hospital
| | - Xiao-Qiang Ding
- Department of Nephrology, Shanghai Institute of Kidney and Dialysis, Shanghai Key Laboratory of Kidney and Blood Purification, Zhongshan Hospital;
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Cationic uremic toxins affect human renal proximal tubule cell functioning through interaction with the organic cation transporter. Pflugers Arch 2013; 465:1701-14. [DOI: 10.1007/s00424-013-1307-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 05/31/2013] [Accepted: 06/02/2013] [Indexed: 01/03/2023]
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Melamed ML, Plantinga L, Shafi T, Parekh R, Meyer TW, Hostetter TH, Coresh J, Powe NR. Retained organic solutes, patient characteristics and all-cause and cardiovascular mortality in hemodialysis: results from the retained organic solutes and clinical outcomes (ROSCO) investigators. BMC Nephrol 2013; 14:134. [PMID: 23806101 PMCID: PMC3698023 DOI: 10.1186/1471-2369-14-134] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 06/17/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Multiple solutes are retained in uremia, but it is currently unclear which solutes are toxic. Small studies suggest that protein-bound solutes, such as p-cresol sulfate and indoxyl sulfate and intracellular solutes, such as methylamine (MMA) and dimethylamine (DMA), may be toxic. Our objective was to test whether elevated levels of these solutes were associated with mortality. METHODS We conducted a prospective cohort study in 521 U.S. incident hemodialysis patients to evaluate associations between these solutes and all-cause and cardiovascular mortality. P-cresol sulfate, indoxyl sulfate, MMA and DMA levels were measured from frozen plasma samples obtained 2 to 6 months after initiation of dialysis. Mortality data was available through 2004 using the National Death Index. RESULTS Elevated (greater than the population median) p-cresol sulfate, MMA or DMA levels were not associated with all-cause or cardiovascular mortality. Elevated indoxyl sulfate levels were associated with all-cause mortality but not cardiovascular mortality (hazard ratio 1.30 (95% confidence interval 1.01, 1.69) p-value 0.043). CONCLUSIONS In this cohort of 521 incident hemodialysis patients, only elevated indoxyl sulfate levels were associated with all-cause mortality. Further research is needed to identify causes of the toxicity of uremia to provide better care for patients with kidney disease.
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Viaene L, Annaert P, de Loor H, Poesen R, Evenepoel P, Meijers B. Albumin is the main plasma binding protein for indoxyl sulfate andp-cresyl sulfate. Biopharm Drug Dispos 2013; 34:165-75. [DOI: 10.1002/bdd.1834] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 12/17/2012] [Accepted: 12/30/2012] [Indexed: 11/05/2022]
Affiliation(s)
| | - Pieter Annaert
- Laboratory for Pharmacotechnology and Biopharmacy, Department of Pharmaceutical and Pharmacological Sciences; KU Leuven; Belgium
| | - Henriette de Loor
- Laboratory of Nephrology, Department of Immunology and Microbiology; KU Leuven; Belgium
| | - Ruben Poesen
- Nephrology; University Hospitals Leuven; Belgium
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Eloot S, Schneditz D, Vanholder R. What can the dialysis physician learn from kinetic modelling beyond Kt/V(urea)? Nephrol Dial Transplant 2012; 27:4021-9. [PMID: 22923544 DOI: 10.1093/ndt/gfs367] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Leypoldt JK, Loghman-Adham M, Jordan P, Reigner B. Effect of hemodialysis and hemofiltration on plasma C.E.R.A. concentrations. Hemodial Int 2012; 16:20-30. [PMID: 22098670 DOI: 10.1111/j.1542-4758.2011.00634.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
C.E.R.A., a continuous erythropoietin receptor activator, is a long-acting erythropoiesis-stimulating agent approved for the treatment of anemia in patients with chronic kidney disease. Although the large molecular weight and the carbohydrate chain make it unlikely that C.E.R.A. could be removed during hemodialysis or hemofiltration, no such data have been published. In vitro studies were performed to assess the removal of C.E.R.A. during hemodialysis and hemofiltration, using both low-flux and high-flux membranes and parameters very similar to those used in clinical practice. Clinical pharmacokinetic studies of plasma C.E.R.A. concentrations in patients undergoing hemodialysis were also performed following subcutaneous injection of C.E.R.A. In the in vitro studies, plasma C.E.R.A. concentrations were not significantly different from baseline values in the primed blood reservoir over a 4-hour period during hemodialysis (P = 0.12). C.E.R.A. concentrations in the plasma obtained from the venous end of the hemofilter increased proportionally with the plasma total protein concentrations, reflecting the consequence of hemoconcentration and suggesting that C.E.R.A and plasma total proteins were retained by hemofiltration membranes to a similar degree. These in vitro studies showed that C.E.R.A. was not removed by simulated hemodialysis or hemofiltration either via transmembrane transport or adsorption to the membrane. The results were corroborated by the clinical pharmacokinetic data, which showed no detectable changes in plasma C.E.R.A. concentrations during hemodialysis using either low-flux or high-flux dialyzers. These results suggest that C.E.R.A. can be administered to patients at any time during hemodialysis or hemofiltration without appreciable loss in the extracorporeal circuit.
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Affiliation(s)
- John K Leypoldt
- Research Service, VA Salt Lake City Healthcare System, Salt Lake City, Utah, USA.
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Meijers B, Toussaint ND, Meyer T, Bammens B, Verbeke K, Vanrenterghem Y, Kerr PG, Evenepoel P. Reduction in protein-bound solutes unacceptable as marker of dialysis efficacy during alternate-night nocturnal hemodialysis. Am J Nephrol 2011; 34:226-32. [PMID: 21791919 DOI: 10.1159/000330176] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2011] [Accepted: 06/17/2011] [Indexed: 11/19/2022]
Abstract
BACKGROUND The uremic retention solutes indoxyl sulfate and p-cresyl sulfate are linked to cardiovascular disease and overall survival. Dialytic clearances are limited, which is principally attributed to tight protein binding. Extending dialysis duration would be expected to substantially increase protein-bound uremic solute removal. The aim of the current study was to study protein-bound uremic retention solute clearances and kinetics during longer-hours nocturnal hemodialysis. METHODS In a prospective cohort study of 32 maintenance alternate-night nocturnal hemodialysis patients, we followed serum concentrations, solute removals and solute clearances of p-cresyl sulfate and indoxyl sulfate. Spent dialysate sampling was fractionated to compare solute removals between the first 4 h and next 4 h of nocturnal dialysis. Single-compartment variable volume kinetics were calculated. RESULTS Dialytic clearances of protein-bound uremic retention solutes are maintained during nocturnal (longer-hours) dialysis. Clearances of indoxyl sulfate exceed those of p-cresyl sulfate, presumably due to less tight protein-binding. Apparent distribution volumes increase substantially during nocturnal dialysis, indicative of multi-compartmental behavior of the protein-bound uremic retention solutes indoxyl sulfate and p-cresyl sulfate. CONCLUSIONS During nocturnal hemodialysis, serum concentrations of protein-bound solute concentrations are reduced less than predicted. Reduction ratios are not a valid tool to estimate total solute removal of protein-bound uremic retention solutes.
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Affiliation(s)
- Bjorn Meijers
- Division of Nephrology, Department of Medicine, University Hospital Leuven, Belgium
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Basile C, Libutti P, Di Turo AL, Casino FG, Vernaglione L, Tundo S, Maselli P, De Nicolo EV, Ceci E, Teutonico A, Lomonte C. Removal of uraemic retention solutes in standard bicarbonate haemodialysis and long-hour slow-flow bicarbonate haemodialysis. Nephrol Dial Transplant 2010; 26:1296-303. [DOI: 10.1093/ndt/gfq543] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Krieter DH, Hackl A, Rodriguez A, Chenine L, Moragues HL, Lemke HD, Wanner C, Canaud B. Protein-bound uraemic toxin removal in haemodialysis and post-dilution haemodiafiltration. Nephrol Dial Transplant 2009; 25:212-8. [DOI: 10.1093/ndt/gfp437] [Citation(s) in RCA: 140] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Luo FJG, Patel KP, Marquez IO, Plummer NS, Hostetter TH, Meyer TW. Effect of Increasing Dialyzer Mass Transfer Area Coefficient and Dialysate Flow on Clearance of Protein-Bound Solutes: A Pilot Crossover Trial. Am J Kidney Dis 2009; 53:1042-9. [DOI: 10.1053/j.ajkd.2009.01.265] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2008] [Accepted: 01/14/2009] [Indexed: 11/11/2022]
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Abstract
PURPOSE OF REVIEW Our concept of uremia has expanded to encompass the illness patients begin to suffer as glomerular filtration rate declines long before the onset of end-stage renal disease (ESRD) not explained by known derangements in volume status or metabolic parameters. New insights into the accumulation of uremic toxins and the loss of function of hormones and enzymes provide important information on the etiology of uremia. RECENT FINDINGS New data are accumulating on the identity and toxicity of uremic toxins and the syndromes that encompass uremia. rho-Cresol sulfate and indoxyl sulfate are small, protein-bound molecules that are poorly cleared with dialysis. These molecules have been linked to cardiovascular disease and oxidative injury. Impaired immunity plays a central role in the morbidity of ESRD and may be both the result of uremic toxicity and a contributor to oxidative stress in ESRD. Uremic cachexia is an underrecognized uremic syndrome. New insights into disordered feeding circuits in ESRD may lead to novel therapies using hormone agonists. SUMMARY Mortality in ESRD remains unacceptably high. It is hoped that as knowledge emerges on the causes and consequences of uremia, we are embarking on an era not only of new insights but also new and effective treatments for patients with the ill effects of uremia.
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Gong D, Ren B, Ji D, Tao J, Xu B, Liu Z, Li Z. Selective albumin exchange: a novel and simple method to remove bilirubin. Int J Artif Organs 2008; 31:425-30. [PMID: 18609516 DOI: 10.1177/039139880803100508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
PURPOSE Owing to its non-selectivity, plasma exchange has limited use in the treatment of patients with hepatic failure, although it is effective in removal of protein-bound toxins. This study reports a novel way to perform selective albumin exchange (SAE) by using a secondary plasma separator and aims to study its depurative capacity in the removal of bilirubin. METHOD In ex vivo experiments, the sieving coefficients (SCs) of plasma proteins for two secondary plasma separators, EC20W and EC30W (Asahi Medical, Tokyo, Japan), were measured. The EC20W membrane was chosen for use in clinical treatment because of its higher selectivity in separating albumin from plasma than the EC30W. The SCs of albumin, immunoglobumin G, A and M (IgG, IgA, IgM) for the EC20W were 0.3+/-0.021, 0.017+/-0.012, and 0, respectively. Five inpatients with plasma total bilirubin (TB) more than 200 micromol/L were enrolled in the present study and received a total of 10 SAE therapy sessions. Each session lasted 10 hours. SAE using the EC20W was conducted, making it similar to post-dilution continuous veno-venous hemofiltration (CVVH), with a filtrate rate of 2000 ml/h. Replacement fluid was composed by adding human albumin into conventional CVVH replacement fluid, with a final albumin concentration of 0.6%. During each treatment, the parameters of plasma and filtrate TB, direct bilirubin (DB), indirect bilirubin (IDB), and proteins were dynamically monitored. Hemostasis parameters were measured before and after sessions. RESULTS The reduction ratio of plasma TB, DB, and IDB after a single session was 29.1+/-3.0%, 31.3+/-4.5%, and 18.7+/-10.2%, respectively. The clearance of TB at initiation was 11.1+/-1.3 mL/min and declined to 4.4+/-0.5 ml/min at the end (p<0.01). This decline was accompanied by a reduction in albumin SC from 0.3+/-0.021 to 0.13+/-0.05. The molar ratio of bilirubin to albumin in filtrate was comparable to that in plasma. After a single treatment, plasma protein concentration including total protein, albumin, IgA and IgM remained unaffected, except for globulin and IgG, which were reduced by 11.5+/-7.8% and 11.1+/-2.3%, respectively. An improvement in hemostasis parameters, including plasma fibrinogen, prothrombase time and INR, was found after treatment. No obvious side effects were reported during any of the sessions. CONCLUSION Selective albumin exchange is a simple and effective method to remove bilirubin. However, further studies are required to verify its effects on clinical outcome.
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Affiliation(s)
- D Gong
- Research Institute of Nephrology, Jinling Hospital, Nanjing University School of Medicine, Nanjing - China.
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Bouchard J, Mehta RL. Acid-base disturbances in the intensive care unit: current issues and the use of continuous renal replacement therapy as a customized treatment tool. Int J Artif Organs 2008; 31:6-14. [PMID: 18286450 DOI: 10.1177/039139880803100103] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Continuous renal replacement therapies (CRRT) are often used to manage complex acid-base problems in critically ill patients. These techniques allow a constant manipulation of the plasma composition. Several technical factors from CRRT influence the acid-base status; namely, the effluent rate, the operational characteristics of the technique, the content of the solutions and the metabolic rate of the buffer. This article reviews the common acid base disorders occurring in the intensive care unit, using both the anion gap and the strong ion gap approaches, and describes the influence of CRRT on acid-base physiology. The use of CRRT as a customized therapy for acid-base disorders is discussed, allowing an integration of both physiological and technical concepts.
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Affiliation(s)
- J Bouchard
- Division of Nephrology, Department of Medicine, University of California San Diego, California - USA
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Meijers BKI, Bammens B, Verbeke K, Evenepoel P. A review of albumin binding in CKD. Am J Kidney Dis 2008; 51:839-50. [PMID: 18436096 DOI: 10.1053/j.ajkd.2007.12.035] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Accepted: 12/05/2007] [Indexed: 01/11/2023]
Abstract
Hypoalbuminemia is associated with excess mortality in patients with kidney disease. Albumin is an important oxidant scavenger and an abundant carrier protein for numerous endogenous and exogenous compounds. Several specific binding sites for anionic, neutral, and cationic ligands were described. Overall, the extent of binding depends on the ligand and albumin concentration, albumin-binding affinity, and presence of competing ligands. Chronic kidney disease affects all these determinants. This may result in altered pharmacokinetics and increased risk of toxicity. Renal clearance of albumin-bound solutes mainly depends on tubular clearance. Dialytic clearance by means of conventional hemodialysis/hemofiltration and peritoneal dialysis is limited. Other epuration techniques combining hemodialysis with adsorption have been developed. However, the benefit of these techniques remains to be proved.
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Affiliation(s)
- Björn K I Meijers
- Department of Medicine, Division of Nephrology, University Hospitals Leuven, Leuven, Belgium
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Abstract
Acute renal failure is a common complication in intensive care medicine. While the incidence of acute renal failure increases, mortality still remains at a high level. In Europe continuous renal replacement therapy (CRRT) has become the standard treatment for acute renal failure. Continuous renal replacement therapy has the advantage of achieving a more stable haemodynamic situation and an easier volume management compared to intermittent haemodialysis (IHD). Until now there has been no evidence to suggest that either classical IHD or CRRT is superior in reducing mortality. Using CRRT in patients with acute renal failure, an ultrafiltration rate adjusted to the patient's bodyweight at 35 ml/kg x h is recommended. A new approach in renal replacement therapy is the slow extended daily dialysis (SLEDD), which combines the advantages of CRRT and IHD. First results are promising, but further investigations are needed to show whether outcome can be improved. A final evidence-based recommendation on the dosing of CRRT or a definitive answer to the question whether daily IHD is better than CRRT, can probably only be possible after two running multicentre studies, the VA/NIH Acute Renal Failure Trial Network (ATN) study and the Augmented Versus Normal Renal Replacement Therapy in Severe Acute Renal Failure Study (ANZICS 2005) Australia and New Zealand Intensive Care Group.
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Les alternatives à l’hémodialyse conventionnelle. Nephrol Ther 2007. [DOI: 10.1016/s1769-7255(07)78755-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Stadlbauer V, Krisper P, Beuers U, Haditsch B, Schneditz D, Jung A, Putz-Bankuti C, Holzer H, Trauner M, Stauber RE. Removal of bile acids by two different extracorporeal liver support systems in acute-on-chronic liver failure. ASAIO J 2007; 53:187-93. [PMID: 17413559 DOI: 10.1097/01.mat.0000249852.71634.6c] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Acute-on-chronic liver failure (ACLF) is accompanied by marked intrahepatic cholestasis leading to accumulation of cytotoxic bile acids. Extracorporeal liver support systems efficiently remove bile acids, but their effect on bile acid composition in ACLF is unknown. The aim of the present study was to compare elimination of individual plasma bile acids by albumin dialysis (Molecular Adsorbents Recirculating System, MARS) and fractionated plasma separation (Prometheus). Eight consecutive patients with ACLF underwent alternating 6-hour sessions with MARS or Prometheus in a randomized, cross-over design. Serum samples were obtained before, during, and after each treatment, and individual bile acids including cholic acid and chenodeoxycholic acid (CDCA) were measured by gas chromatography. MARS and Prometheus removed total bile acids to a similar extent (reduction ratio, 45% and 46%, respectively). Both devices cleared cholic acid more efficiently than did CDCA. The molar fraction of CDCA (fCDCA) was elevated at baseline and correlated with the degree of liver dysfunction. Prometheus but not MARS treatments further increased fCDCA. Although both devices eliminate total bile acids to a similar extent, clearance of individual bile acids is different, leading to a slight change of the bile acid profile toward hydrophobic bile acids during Prometheus treatments.
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Affiliation(s)
- Vanessa Stadlbauer
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Medical University of Graz, Graz, Austria
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Meyer TW, Peattie JWT, Miller JD, Dinh DC, Recht NS, Walther JL, Hostetter TH. Increasing the Clearance of Protein-Bound Solutes by Addition of a Sorbent to the Dialysate. J Am Soc Nephrol 2007; 18:868-74. [PMID: 17251385 DOI: 10.1681/asn.2006080863] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The capacity of sorbent systems to increase solute clearances above the levels that are provided by hemodialysis has not been well defined. This study assessed the extent to which solute clearances can be increased by addition of a sorbent to the dialysate. Attention was focused on the clearance of protein-bound solutes, which are cleared poorly by conventional hemodialysis. A reservoir that contained test solutes and artificial plasma was dialyzed first with the plasma flow set at 46 +/- 3 ml/min and the dialysate flow (Q(d)) set at 42 +/- 3 ml/min using a hollow fiber kidney with mass transfer area coefficients greater than Q(d) for each of the solutes. Under these conditions, the clearance of urea (Cl(urea)) was 34 +/- 1 ml/min, whereas the clearances of the protein-bound solutes indican (Cl(ind)), p-cresol sulfate (Cl(pcs)), and p-cresol (Cl(pc)) averaged only 5 +/- 1, 4 +/- 1, and 14 +/- 1 ml/min, respectively The effect of addition of activated charcoal to the dialysate then was compared with the effect of increasing Q(d) without addition of any sorbent. Addition of charcoal increased Cl(ind), Cl(pcs), and Cl(pc) to 12 +/- 1, 9 +/- 2, and 35 +/- 4 ml/min without changing Cl(urea). Increasing Q(d) without the addition of sorbent had a similar effect on the clearance of the protein-bound solutes. Mathematical modeling predicted these changes and showed that the maximal effect of addition of a sorbent to the dialysate is equivalent to that of an unlimited increase in Q(d). These results suggest that as an adjunct to conventional hemodialysis, addition of sorbents to the dialysate could increase the clearance of protein-bound solutes without greatly altering the clearance of unbound solutes.
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Affiliation(s)
- Timothy W Meyer
- Department of Medicine, VA Palo Alto HCS, Palo Alto, CA 94303, USA.
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Meyer T, Hostetter T. Response to ‘Downloadable computer models for maintenance but not acute renal replacement therapy’. Kidney Int 2006. [DOI: 10.1038/sj.ki.5001672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Walther JL, Bartlett DW, Chew W, Robertson CR, Hostetter TH, Meyer TW. Downloadable computer models for renal replacement therapy. Kidney Int 2006; 69:1056-63. [PMID: 16528255 DOI: 10.1038/sj.ki.5000196] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mathematical models can predict solute clearances and solute concentrations during renal replacement therapy. At present, however, most nephrologists cannot use these models because they require mathematical software. In this report, we describe models of solute transport by convection and diffusion adapted to run on the commonly available software program Excel for Macintosh computers and PCs running Windows. Two programs have been created that can be downloaded from http://www.stanford.edu/~twmeyer/ or http://dev.satellitehealth.com/research/journal.asp. The first, called 'Dr Addis Clearance Calculator', calculates clearance values from inputs including the blood flow Q(b), the hematocrit, the ultrafiltration rate Q(f), the dialysate flow rate Q(d), the reflection coefficient sigma and the mass transfer area coefficient K(o)A for the solute of interest, and the free fraction f if the solute is protein bound. Solute concentration profiles along the length of the artificial kidney are displayed graphically. The second program, called 'Dr Coplon Dialysis Simulator', calculates plasma solute concentrations from the clearance values obtained by the first program and from additional input values including the number of treatments per week, the duration of the treatments, and the solute's production rate and volumes of distribution. The program calculates the time-averaged solute concentration and provides a graphic display of the solute concentration profile through a week-long interval.
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Affiliation(s)
- J L Walther
- Department of Medicine, VA Palo Alto HCS and Stanford University, Palo Alto, California 94304, USA
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Martinez AW, Recht NS, Hostetter TH, Meyer TW. Removal of P-cresol sulfate by hemodialysis. J Am Soc Nephrol 2005; 16:3430-6. [PMID: 16120820 DOI: 10.1681/asn.2005030310] [Citation(s) in RCA: 214] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Protein-bound solutes are poorly cleared by dialysis. Among the most extensively studied of these solutes is p-cresol, which has been shown to be toxic in vitro. This study examined the form in which p-cresol circulates and quantified its removal by hemodialysis. HPLC analysis of plasma from hemodialysis patients contained a peak whose mobility corresponded to synthetic p-cresol sulfate (PCS) but no detectable unconjugated p-cresol. Treatment with sulfatase resulted in recovery of this peak as p-cresol, confirming its identity. Subsequent studies compared the removal of PCS and another protein-bound solute, indican, to the removal of urea during clinical hemodialysis treatments. PCS and indican were 94 +/- 1% and 93 +/- 2% bound to plasma protein, respectively. Protein-binding caused a predictable decrease in measured dialytic clearance, which averaged 20 +/- 4 ml/min for PCS and 25 +/- 5 ml/min for indican as compared with 260 +/- 20 ml/min for urea. Volumes of distribution for the protein-bound solutes were greater than the plasma volume, averaging 15 +/- 7 L for PCS and 14 +/- 3 L for indican as compared with 37 +/- 7 for urea. Solute reduction ratios were 20 +/- 9% for PCS, 30 +/- 7% for indican, and 69 +/- 5% for urea. We conclude that p-cresol circulates in the form of its sulfate conjugate, PCS. PCS is poorly removed by hemodialysis because its clearance is limited by protein binding and the ratio of its volume of distribution to its clearance is high.
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Affiliation(s)
- Andres W Martinez
- Department of Medicine, Veterans Association, Palo Alto, California, USA
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