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Zhang X, Lumen A, Wong H, Connarn J, Dutta S, Upreti VV. A Mechanistic Physiologically-Based Pharmacokinetic Platform Model to Guide Adult and Pediatric Intravenous and Subcutaneous Dosing for Bispecific T Cell Engagers. Clin Pharmacol Ther 2024; 115:457-467. [PMID: 37746860 DOI: 10.1002/cpt.3056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 09/11/2023] [Indexed: 09/26/2023]
Abstract
Bispecific T cell engagers (Bi-TCEs) have revolutionized the treatment of oncology indications across both liquid and solid tumors. Bi-TCEs are rapidly evolving from conventional intravenous (i.v.) to more convenient subcutaneous (s.c.) administrations and extending beyond adults to also benefit pediatric patients. Leveraging clinical development experience across three generations of Bi-TCE molecules across both liquid and solid tumor indications from i.v./s.c. dosing in adults and pediatric subjects, we developed a mechanistic-physiologically-based pharmacokinetic (PBPK) platform model for Bi-TCEs. The model utilizes a full PBPK model framework and was successfully validated for PK predictions following i.v. and s.c. dosing across both liquid and solid tumor space in adults for eight Bi-TCEs. After refinement to incorporate physiological ontogeny, the model was successfully validated to predict pediatric PKs in 1 month - < 2 years, 2-11 years, and 12-17 years old subjects following i.v. dosing. Following s.c. dosing in pediatric subjects, the model predicted similar bioavailability, however, a shorter time to maximum concentration (Tmax ) for the three age groups compared with adults. The model was also applied to guide the dosing strategy for first generation of Bi-TCEs for organ impairment, specifically renal impairment, and was able to accurately predict the impact of renal impairment on PK for these relatively small-size Bi-TCEs. This work highlights a novel mechanistic platform model for accurately predicting the PK in adult and pediatric patients across liquid and solid tumor indications from i.v./s.c. dosing and can be used to guide optimal dose and dosing regimen selection and accelerating the clinical development for Bi-TCEs.
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Affiliation(s)
- Xinwen Zhang
- Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., South San Francisco, California, USA
| | - Annie Lumen
- Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., South San Francisco, California, USA
| | - Hansen Wong
- Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., South San Francisco, California, USA
| | - Jamie Connarn
- Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., South San Francisco, California, USA
| | - Sandeep Dutta
- Clinical Pharmacology, Modeling and Simulation, Amgen Inc., Thousand Oaks, California, USA
| | - Vijay V Upreti
- Clinical Pharmacology, Modeling, and Simulation, Amgen Inc., South San Francisco, California, USA
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Malmgren L, Öberg C, den Bakker E, Leion F, Siódmiak J, Åkesson A, Lindström V, Herou E, Dardashti A, Xhakollari L, Grubb G, Strevens H, Abrahamson M, Helmersson-Karlqvist J, Magnusson M, Björk J, Nyman U, Ärnlöv J, Ridefelt P, Åkerfeldt T, Hansson M, Sjöström A, Mårtensson J, Itoh Y, Grubb D, Tenstad O, Hansson LO, Olafsson I, Campos AJ, Risch M, Risch L, Larsson A, Nordin G, Pottel H, Christensson A, Bjursten H, Bökenkamp A, Grubb A. The complexity of kidney disease and diagnosing it - cystatin C, selective glomerular hypofiltration syndromes and proteome regulation. J Intern Med 2023; 293:293-308. [PMID: 36385445 PMCID: PMC10107454 DOI: 10.1111/joim.13589] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Estimation of kidney function is often part of daily clinical practice, mostly done by using the endogenous glomerular filtration rate (GFR)-markers creatinine or cystatin C. A recommendation to use both markers in parallel in 2010 has resulted in new knowledge concerning the pathophysiology of kidney disorders by the identification of a new set of kidney disorders, selective glomerular hypofiltration syndromes. These syndromes, connected to strong increases in mortality and morbidity, are characterized by a selective reduction in the glomerular filtration of 5-30 kDa molecules, such as cystatin C, compared to the filtration of small molecules <1 kDa dominating the glomerular filtrate, for example water, urea and creatinine. At least two types of such disorders, shrunken or elongated pore syndrome, are possible according to the pore model for glomerular filtration. Selective glomerular hypofiltration syndromes are prevalent in investigated populations, and patients with these syndromes often display normal measured GFR or creatinine-based GFR-estimates. The syndromes are characterized by proteomic changes promoting the development of atherosclerosis, indicating antibodies and specific receptor-blocking substances as possible new treatment modalities. Presently, the KDIGO guidelines for diagnosing kidney disorders do not recommend cystatin C as a general marker of kidney function and will therefore not allow the identification of a considerable number of patients with selective glomerular hypofiltration syndromes. Furthermore, as cystatin C is uninfluenced by muscle mass, diet or variations in tubular secretion and cystatin C-based GFR-estimation equations do not require controversial race or sex terms, it is obvious that cystatin C should be a part of future KDIGO guidelines.
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Affiliation(s)
- Linnea Malmgren
- Department of Clinical Sciences Malmö, Clinical and Molecular Osteoporosis Research Unit, Lund University, Malmö, Sweden.,Department of Geriatrics, Skåne University Hospital, Malmö, Sweden
| | - Carl Öberg
- Department of Clinical Sciences Lund, Division of Nephrology, Skåne University Hospital, Lund University, Lund, Sweden
| | - Emil den Bakker
- Department of Pediatrics, Amsterdam University Medical Centre, Amsterdam, The Netherlands
| | - Felicia Leion
- Department of Clinical Chemistry, Skåne University Hospital, Lund University, Lund, Sweden
| | - Joanna Siódmiak
- Department of Laboratory Medicine, Faculty of Pharmacy, Ludwik Rydygier Collegium Medicum (Nicolaus Copernicus University in Torun), Bydgoszcz, Poland
| | - Anna Åkesson
- Division of Occupational and Environmental Medicine, Lund University, Lund, Sweden.,Clinical Studies Sweden, Forum South, Skåne University Hospital, Lund, Sweden
| | - Veronica Lindström
- Department of Clinical Chemistry, Skåne University Hospital, Lund University, Lund, Sweden
| | - Erik Herou
- Department of Cardiothoracic Surgery, Skåne University Hospital, Lund University, Lund, Sweden
| | - Alain Dardashti
- Department of Cardiothoracic Surgery, Skåne University Hospital, Lund University, Lund, Sweden
| | - Liana Xhakollari
- Department of Clinical Sciences, Lund University, Malmö, Sweden.,Department of Nephrology, Skåne University Hospital, Lund University, Malmö, Sweden
| | - Gabriel Grubb
- Department of Radiology, Skåne University Hospital, Lund, Sweden
| | - Helena Strevens
- Department of Clinical Sciences Lund, Department of Obstetrics and Gynaecology, Lund University, Lund, Sweden
| | - Magnus Abrahamson
- Department of Clinical Chemistry, Skåne University Hospital, Lund University, Lund, Sweden
| | | | - Martin Magnusson
- Department of Clinical Sciences, Lund University, Malmö, Sweden.,Department of Cardiology, Skåne University Hospital, Malmö, Sweden.,Wallenberg Center for Molecular Medicine, Lund University, Lund, Sweden.,Hypertension in Africa Research Team (HART), North West University, Potchefstroom, South Africa
| | - Jonas Björk
- Division of Occupational and Environmental Medicine, Lund University, Lund, Sweden.,Clinical Studies Sweden, Forum South, Skåne University Hospital, Lund, Sweden
| | - Ulf Nyman
- Department of Translational Medicine, Division of Medical Radiology, University of Lund, Malmö, Sweden
| | - Johan Ärnlöv
- Department of Neurobiology, Care Sciences and Society (NVS), Family Medicine and Primary Care Unit, Karolinska Institute, Huddinge, Sweden.,School of Health and Social Studies, Dalarna University, Falun, Sweden
| | - Peter Ridefelt
- Department of Medical Sciences, Clinical Chemistry, Uppsala University Hospital, Uppsala, Sweden
| | - Torbjörn Åkerfeldt
- Department of Medical Sciences, Clinical Chemistry, Uppsala University Hospital, Uppsala, Sweden
| | - Magnus Hansson
- Department of Clinical Chemistry, Karolinska University Hospital, Huddinge, Sweden
| | - Anna Sjöström
- Department of Clinical Chemistry, Karolinska University Hospital, Huddinge, Sweden
| | - Johan Mårtensson
- Department of Physiology and Pharmacology, Section of Anaesthesia and Intensive Care, Karolinska Institute, Stockholm, Sweden
| | - Yoshihisa Itoh
- Clinical Laboratory, Eiju General Hospital, Life Extension Research Institute, Tokyo, Japan
| | - David Grubb
- Department of Cardiothoracic Surgery, Skåne University Hospital, Lund University, Lund, Sweden
| | - Olav Tenstad
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Lars-Olov Hansson
- Department of Clinical Chemistry, Karolinska University Hospital, Huddinge, Sweden
| | - Isleifur Olafsson
- Department of Clinical Biochemistry, Landspitali - National University Hospital of Iceland, Reykjavik, Iceland
| | - Araceli Jarquin Campos
- Faculty of Medical Sciences, Private University in the Principality of Liechtenstein, Triesen, Liechtenstein
| | - Martin Risch
- Central Laboratory, Cantonal Hospital Graubünden, Chur, Switzerland
| | - Lorenz Risch
- Faculty of Medical Sciences, Private University in the Principality of Liechtenstein, Triesen, Liechtenstein.,University Institute of Clinical Chemistry, University Hospital and University of Bern, Inselspital, Bern, Switzerland
| | - Anders Larsson
- Department of Medical Sciences, Clinical Chemistry, Uppsala University Hospital, Uppsala, Sweden
| | | | - Hans Pottel
- Department of Public Health and Primary Care, Katholieke Universiteit Leuven Campus Kulak Kortrijk, Kortrijk, Belgium
| | - Anders Christensson
- Department of Nephrology, Skåne University Hospital, Lund University, Malmö, Sweden
| | - Henrik Bjursten
- Department of Cardiothoracic Surgery, Skåne University Hospital, Lund University, Lund, Sweden
| | - Arend Bökenkamp
- Department of Pediatric Nephrology, Emma Children's Hospital, Amsterdam University Medical Centers, Amsterdam, The Netherlands
| | - Anders Grubb
- Department of Clinical Chemistry, Skåne University Hospital, Lund University, Lund, Sweden
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3
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Wang D, Sant S, Ferrell N. A Biomimetic In Vitro Model of the Kidney Filtration Barrier Using Tissue-Derived Glomerular Basement Membrane. Adv Healthc Mater 2021; 10:e2002275. [PMID: 34218528 DOI: 10.1002/adhm.202002275] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 05/24/2021] [Indexed: 01/28/2023]
Abstract
The glomerular filtration barrier (GFB) filters the blood to remove toxins while retaining high molecular weight proteins in the circulation. The glomerular basement membrane (GBM) and podocytes, highly specialized epithelial cells, are critical components of the filtration barrier. The GBM serves as a physical barrier to passage of molecules into the filtrate. Podocytes adhere to the filtrate side of the GBM and further restrict passage of high molecular weight molecules into the filtrate. Here, a 3D cell culture model of the glomerular filtration barrier to evaluate the role of the GBM and podocytes in mediating molecular diffusion is developed. GBM is isolated from mammalian kidneys to recapitulate the composition and mechanics of the in vivo basement membrane. The GFB model exhibits molecular selectivity that is comparable to the in vivo filtration barrier. The GBM alone provides a stringent barrier to passage of albumin and Ficoll. Podocytes further restrict molecular diffusion. Damage to the GBM that is typical of diabetic kidney disease is simulated using hypochlorous acid and results in increased molecular diffusion. This system can serve as a platform to evaluate the effects of GBM damage, podocyte injury, and reciprocal effects of altered podocyte-GBM interactions on kidney microvascular permeability.
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Affiliation(s)
- Dan Wang
- Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, 1161 21st Ave. South, Nashville, TN, 37232, USA
| | - Snehal Sant
- Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, 1161 21st Ave. South, Nashville, TN, 37232, USA
| | - Nicholas Ferrell
- Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, 1161 21st Ave. South, Nashville, TN, 37232, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37235, USA
- Vanderbilt Center for Kidney Disease, S3223 Medical Center North, Nashville, TN, 37232, USA
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4
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Öberg CM, Lindström M, Grubb A, Christensson A. Potential relationship between eGFR cystatin C /eGFR creatinine -ratio and glomerular basement membrane thickness in diabetic kidney disease. Physiol Rep 2021; 9:e14939. [PMID: 34254743 PMCID: PMC8276256 DOI: 10.14814/phy2.14939] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Accepted: 05/28/2021] [Indexed: 12/04/2022] Open
Abstract
Diabetic kidney disease (DKD) is a leading cause of end-stage renal disease and renal replacement therapy worldwide. A pathophysiological hallmark of DKD is glomerular basal membrane (GBM) thickening, whereas this feature is absent in minimal change disease (MCD). According to fundamental transport physiological principles, a thicker GBM will impede the diffusion of middle-molecules such as cystatin C, potentially leading to a lower estimated GFR (eGFR) from cystatin C compared to that of creatinine. Here we test the hypothesis that thickening of the glomerular filter leads to an increased diffusion length, and lower clearance, of cystatin C. Twenty-nine patients with a kidney biopsy diagnosis of either DKD (n = 17) or MCD (n = 12) were retrospectively included in the study. GBM thickness was measured at 20 separate locations in the biopsy specimen and plasma levels of cystatin C and creatinine were retrieved from health records. A modified two-pore model was used to simulate the effects of a thicker GBM on glomerular water and solute transport. The mean age of the patients was 52 years, and 38% were women. The mean eGFRcystatin C /eGFRcreatinine -ratio was 74% in DKD compared to 98% in MCD (p < 0.001). Average GBM thickness was strongly inversely correlated to the eGFRcystatin C /eGFRcreatinine -ratio (Pearson's r = -0.61, p < 0.01). Two-pore modeling predicted a eGFRcystatin C /eGFRcreatinine -ratio of 78% in DKD. We provide clinical and theoretical evidence suggesting that thickening of the glomerular filter, increasing the diffusion length of cystatin C, lowers the eGFRcystatin C /eGFRcreatinine -ratio in DKD.
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Affiliation(s)
- Carl M. Öberg
- Department of Clinical Sciences LundLund UniversityLundSweden
- Department of NephrologySkåne University HospitalLundSweden
| | - Martin Lindström
- Department of Laboratory Medicine MalmöLund UniversityMalmöSweden
- Center for Molecular PathologySkåne University HospitalMalmöSweden
| | - Anders Grubb
- Department of Laboratory MedicineLund UniversityLundSweden
- Department of Clinical ChemistrySkåne University HospitalLundSweden
| | - Anders Christensson
- Department of Clinical Sciences MalmöLund UniversityLundSweden
- Department of NephrologySkåne University HospitalMalmöSweden
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5
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Dolinina J, Rippe A, Öberg CM. Clemizole and La 3+ salts ameliorate angiotensin II-induced glomerular hyperpermeability in vivo. Physiol Rep 2021; 9:e14781. [PMID: 34042270 PMCID: PMC8157770 DOI: 10.14814/phy2.14781] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 01/29/2021] [Accepted: 02/05/2021] [Indexed: 01/01/2023] Open
Abstract
Angiotensin II (Ang II) induces marked, dynamic increases in the permeability of the glomerular filtration barrier (GFB) in rats. After binding to its receptor, Ang II elicits Ca2+ influx into cells, mediated by TRPC5 and TRPC6 (transient receptor potential canonical type 5 and 6). Clemizole and La3+ salts have been shown to block TRPC channels in vitro, and we therefore tested their potential effect on Ang II‐induced glomerular hyperpermeability. Anesthetized male Sprague‐Dawley rats were infused with Ang II (80 ng kg–1 min–1) alone, or together with clemizole or low‐dose La3+ (activates TRPC5, blocks TRPC6) or high‐dose La3+ (blocks both TRPC5 and TRPC6). Plasma and urine samples were taken during baseline and at 5 min after the start of the infusions and analyzed by high‐performance size‐exclusion chromatography for determination of glomerular sieving coefficients for Ficoll 10–80 Å (1–8 nm). Ang II infusion evoked glomerular hyperpermeability to large Ficolls (50–80 Å), which was ameliorated by clemizole, having no significant effect on glomerular filtration rate (GFR) or Ang II‐mediated increase in mean arterial pressure (ΔMAP). In contrast, high‐ and low‐dose La3+ significantly lowered ΔMAP and reduced Ang II‐induced hyperpermeability. Combined, clemizole and low‐dose La3+ were less effective at ameliorating Ang II‐induced glomerular hyperpermeability than low‐dose La3+ alone. In conclusion, our data show that both clemizole and La3+ are effective against Ang II‐induced glomerular hyperpermeability, with differential effects on blood pressure. Further research using more specific blockers of TRPC5 and TRPC6 should be performed to reveal the underlying mechanisms.
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Affiliation(s)
- Julia Dolinina
- Department of Nephrology, Clinical Sciences Lund, Lund University, Lund, Sweden
| | - Anna Rippe
- Department of Nephrology, Clinical Sciences Lund, Lund University, Lund, Sweden
| | - Carl M Öberg
- Department of Nephrology, Clinical Sciences Lund, Lund University, Lund, Sweden
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6
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Storr M, Ward RA. Membrane innovation: closer to native kidneys. Nephrol Dial Transplant 2019; 33:iii22-iii27. [PMID: 30281130 PMCID: PMC6168921 DOI: 10.1093/ndt/gfy228] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Accepted: 06/19/2018] [Indexed: 12/11/2022] Open
Abstract
Modern methods in analytical biochemistry have established that uraemia is associated with the retention of proteins, both in their native state and post-translationally modified, over a wide range of molecular weights up to 60 kDa. Evidence is accumulating that these higher molecular weight retention solutes are important uraemic toxins, and therapies such as online haemodiafiltration (HDF), which enhance their removal, are associated with improved outcomes. However, HDF has limitations regarding cost, clinical implementation and the need for an external source of sterile substitution solution to maintain fluid balance. New membranes that have a solute removal profile more closely approaching that of the glomerular filtration barrier when used for conventional haemodialysis, while at the same time not allowing the passage of clinically significant amounts of beneficial proteins, are needed to address these limitations. Tighter control of the molecular characteristics of the polymers used for membrane fabrication, along with the introduction of additives and improvements in the manufacturing process, has led to membranes with a tighter pore size distribution that allows the use of an increased absolute pore size without leaking substantial amounts of albumin. At the same time, the wall thickness and internal diameter of membrane fibres have been decreased, enhancing convective transport within the dialyser without the need for an external source of substitution solution. These new expanded range membranes provide a solute removal profile more like that of the native kidney than currently available membranes when used in conventional haemodialysis.
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Affiliation(s)
- Markus Storr
- Baxter International, Research and Development, Hechingen, Germany
- Correspondence and offprint requests to: Markus Storr; E-mail:
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7
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Bakoush O, Lubbad L, Öberg CM, Hammad FT. Effect of diabetes mellitus on the recovery of changes in renal functions and glomerular permeability following reversible 24-hour unilateral ureteral obstruction. J Diabetes 2019; 11:674-683. [PMID: 30592154 DOI: 10.1111/1753-0407.12893] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 11/06/2018] [Accepted: 12/26/2018] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Following reversal of short periods of ureteral obstruction (UO), glomerular and tubular renal dysfunction recovers with time. Diabetes mellitus (DM) affects glomerular function; thus, the ability of diabetic kidneys to recover from UO may be impaired. This study investigated the effects of long-term DM on the recovery of glomerular and tubular function, as well as permeability of the glomerular filtration barrier (GFB), after unilateral UO (UUO) reversal. METHODS Diabetes mellitus was induced in Wistar rats by intraperitoneal streptozotocin. All diabetic and age-matched control rats underwent reversible 24-hour left UUO. The renal function of both kidneys was measured using clearance techniques 3 hours and 7 and 30 days after UUO reversal. Glomerular permeability was assessed by measuring the glomerular sieving coefficients for fluorescein isothiocyanate-conjugated Ficoll (molecular radius: 20-90 Å). RESULTS Unilateral UO induced transient changes in the size selectivity of GFB small pores. However, the size selectivity function of large pores had not returned to baseline even 30 days after UUO reversal. Diabetes mellitus caused exaggerated early alterations in glomerular hemodynamic and tubular function, as well as size selectivity dysfunction of both small and large pores. At 30 days after UUO reversal, despite glomerular hemodynamic and tubular function and the size selectivity of small pores returning to normal in both diabetic and non-diabetic rats, the residual size selectivity dysfunction of large pores was more severe in diabetic rats. CONCLUSION Unilateral UO caused long-term dysfunction in the size selectivity of large pores of the GFB. In addition, DM significantly exaggerated this dysfunction, indicating a more ominous outcome in diabetic kidneys following UUO.
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Affiliation(s)
- Omran Bakoush
- Department of Internal Medicine, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Loay Lubbad
- Department of Surgery, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Carl M Öberg
- Department of Nephrology, Clinical Sciences Lund, Lund University, Lund, Sweden
| | - Fayez T Hammad
- Department of Surgery, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
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8
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Dolinina J, Rippe A, Öberg CM. Sustained, delayed, and small increments in glomerular permeability to macromolecules during systemic ET-1 infusion mediated via the ET A receptor. Am J Physiol Renal Physiol 2019; 316:F1173-F1179. [PMID: 30864842 DOI: 10.1152/ajprenal.00040.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Emerging evidence indicates that endogenous production of endothelin (ET)-1, a 21-amino acid peptide vasoconstrictor, plays an important role in proteinuric kidney disease. Previous studies in rats have shown that chronic administration of ET-1 leads to increased glomerular albumin leakage. The underlying mechanisms are, however, currently not known. Here, we used size-exclusion chromatography to measure glomerular sieving coefficients for neutral FITC-Ficoll (molecular Stokes-Einstein radius: 15-80 Å, molecular weight: 70 kDa/400 kDa) in anesthetized male Sprague-Dawley rats (n = 12) at baseline and at 5, 15, 30, and 60 min after intravenous administration of ET-1. In separate experiments, ET-1 was given together with the selective ET type A (ETA) or ET type B (ETB) receptor antagonists JKC-301 and BQ-788, respectively. At both 15 and 30 min postadministration, the glomerular sieving coefficient for macromolecular Ficoll (70 Å) was significantly increased to 4.4 × 10-5 ± 0.7 × 10-5 (P = 0.024) and 4.5 × 10-5 ± 0.8 × 10-5 (P = 0.007), respectively, compared with baseline (2.2 × 10-5 ± 0.4 ×10-5). Decreased urine production after ET-1 prevented the use of higher doses of ET-1. Data analysis using the two-pore model indicated changes in large-pore permeability after ET-1, with no changes in the small-pore pathway. Administration of ETA blocker abrogated the permeability changes induced by ET-1 at 30 min, whereas blockade of ETB receptors was ineffective. Mean arterial pressure was only significantly increased at 60 min, being 123 ± 4 mmHg compared with 111 ± 2 mmHg at baseline (P = 0.02). We conclude that ET-1 evoked small, delayed, and sustained increases in glomerular permeability, mediated via the ETA receptor.
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Affiliation(s)
- Julia Dolinina
- Department of Nephrology, Skåne University Hospital, Clinical Sciences Lund, Lund University , Lund , Sweden
| | - Anna Rippe
- Department of Nephrology, Skåne University Hospital, Clinical Sciences Lund, Lund University , Lund , Sweden
| | - Carl M Öberg
- Department of Nephrology, Skåne University Hospital, Clinical Sciences Lund, Lund University , Lund , Sweden
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9
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Öberg CM, Martuseviciene G. Computer Simulations of Continuous Flow Peritoneal Dialysis Using the 3-Pore Model-A First Experience. Perit Dial Int 2019; 39:236-242. [PMID: 30846606 DOI: 10.3747/pdi.2018.00225] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 12/28/2018] [Indexed: 11/15/2022] Open
Abstract
Background:Continuous flow peritoneal dialysis (CFPD) is performed using a continuous flux of dialysis fluid via double or dual-lumen PD catheters, allowing a higher dialysate flow rate (DFR) than conventional treatments. While small clinical studies have revealed greatly improved clearances using CFPD, the inability to predict ultrafiltration (UF) may confer a risk of potentially harmful overfill. Here we performed physiological studies of CFPD in silico using the extended 3-pore model.Method:A 9-h CFPD session was simulated for: slow (dialysate to plasma creatinine [D/P crea] < 0.6), fast (D/P crea > 0.8) and average (0.6 ≤ D/P crea ≤ 0.8) transporters using 1.36%, 2.27%, or 3.86% glucose solutions. To avoid overfill, we applied a practical equation, based on the principle of mass-balance, to predict the UF rate during CFPD treatment.Results:Increasing DFR > 100 mL/min evoked substantial increments in small- and middle-molecule clearances, being 2 - 5 times higher compared with a 4-h continuous ambulatory PD (CAPD) exchange, with improvements typically being smaller for average and slow transporters. Improved UF rates, exceeding 10 mL/min, were achieved for all transport types. The β2-microglobulin clearance was strongly dependent on the UF rate and increased between 60% and 130% as a function of DFR. Lastly, we tested novel intermittent-continuous regimes as an alternative strategy to prevent overfill, being effective for 1.36% and 2.27%, but not for 3.86% glucose.Conclusion:While we find substantial increments in solute and water clearance with CFPD, previous studies have shown similar improvements using high-volume tidal automated PD (APD). Lastly, the current in silico results need confirmation by studies in vivo.
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Affiliation(s)
- Carl M Öberg
- Renal Physiology and Peritoneal Dialysis Group, Department of Clinical Sciences Lund, Lund University, Lund, Sweden
| | - Giedre Martuseviciene
- Renal Physiology and Peritoneal Dialysis Group, Department of Clinical Sciences Lund, Lund University, Lund, Sweden
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10
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Voinova M, Repin N, Sokol E, Tkachuk B, Gorelik L. Physical Processes in Polymeric Filters Used for Dialysis. Polymers (Basel) 2019; 11:E389. [PMID: 30960373 PMCID: PMC6473866 DOI: 10.3390/polym11030389] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Revised: 02/06/2019] [Accepted: 02/12/2019] [Indexed: 01/03/2023] Open
Abstract
The key physical processes in polymeric filters used for the blood purification include transport across the capillary wall and the interaction of blood cells with the polymer membrane surface. Theoretical modeling of membrane transport is an important tool which provides researchers with a quantification of the complex phenomena involved in dialysis. In the paper, we present a dense review of the most successful theoretical approaches to the description of transport across the polymeric membrane wall as well as the cell⁻polymer surface interaction, and refer to the corresponding experimental methods while studying these phenomena in dialyzing filters.
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Affiliation(s)
- Marina Voinova
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden.
- Department of Industrial and Biomedical Electronics, Kharkiv Polytechnical Institute, National Technical University, 61002 Kharkov, Ukraine.
| | - Nikolay Repin
- Department of Cryomorphology, Institute for Problems of Cryobiology and Cryomedicine, 61015 Kharkov, Ukraine.
| | - Evgen Sokol
- Department of Industrial and Biomedical Electronics, Kharkiv Polytechnical Institute, National Technical University, 61002 Kharkov, Ukraine.
| | - Bogdan Tkachuk
- Department of Hemodialysis, Municipal Noncommercial Enterprise of Kharkiv Regional Council "Regional Medical Clinical Center of Urology and Nephrology n.a. V.I. Shapoval", 61037 Kharkov, Ukraine.
| | - Leonid Gorelik
- Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden.
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11
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Maeda A, Himeno Y, Ikebuchi M, Noma A, Amano A. Regulation of the glucose supply from capillary to tissue examined by developing a capillary model. J Physiol Sci 2018; 68:355-367. [PMID: 28417297 PMCID: PMC10717424 DOI: 10.1007/s12576-017-0538-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Accepted: 04/05/2017] [Indexed: 10/19/2022]
Abstract
A new glucose transport model relying upon diffusion and convection across the capillary membrane was developed, and supplemented with tissue space and lymph flow. The rate of glucose utilization (J util) in the tissue space was described as a saturation function of glucose concentration in the interstitial fluid (C glu,isf), and was varied by applying a scaling factor f to J max. With f = 0, the glucose diffusion ceased within ~20 min. While, with increasing f, the diffusion was accelerated through a decrease in C glu,isf, but the convective flux remained close to resting level. When the glucose supplying capacity of the capillary was measured with a criterion of J util /J max = 0.5, the capacity increased in proportion to the number of perfused capillaries. A consistent profile of declining C glu,isf along the capillary axis was observed at the criterion of 0.5 irrespective of the capillary number. Increasing blood flow scarcely improved the supplying capacity.
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Affiliation(s)
- Akitoshi Maeda
- Department of Life Sciences, Ritsumeikan University, Shiga, Japan
| | - Yukiko Himeno
- Department of Life Sciences, Ritsumeikan University, Shiga, Japan
| | | | - Akinori Noma
- Department of Life Sciences, Ritsumeikan University, Shiga, Japan.
| | - Akira Amano
- Department of Life Sciences, Ritsumeikan University, Shiga, Japan
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12
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Punyaratabandhu N, Kongoup P, Dechadilok P, Katavetin P, Triampo W. Transport of Spherical Particles Through Fibrous Media and a Row of Parallel Cylinders: Applications to Glomerular Filtration. J Biomech Eng 2018; 139:2648279. [PMID: 28779521 DOI: 10.1115/1.4037550] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Indexed: 11/08/2022]
Abstract
Viewed in renal physiology as a refined filtration device, the glomerulus filters large volumes of blood plasma while keeping proteins within blood circulation. Effects of macromolecule size and macromolecule hydrodynamic interaction with the nanostructure of the cellular layers of the glomerular capillary wall on the glomerular size selectivity are investigated through a mathematical simulation based on an ultrastructural model. The epithelial slit, a planar arrangement of fibers connecting the epithelial podocytes, is represented as a row of parallel cylinders with nonuniform spacing between adjacent fibers. The mean and standard deviation of gap half-width between its fibers are based on values recently reported from electron microscopy. The glomerular basement membrane (GBM) is represented as a fibrous medium containing fibers of two different sizes: the size of type IV collagens and that of glycosaminoglycans (GAGs). The endothelial cell layer is modeled as a layer full of fenestrae that are much larger than solute size and filled with GAGs. The calculated total sieving coefficient agrees well with the sieving coefficients of ficolls obtained from in vivo urinalysis in humans, whereas the computed glomerular hydraulic permeability also falls within the range estimated from human glomerular filtration rate (GFR). Our result indicates that the endothelial cell layer and GBM significantly contribute to solute and fluid restriction of the glomerular barrier, whereas, based on the structure of the epithelial slit obtained from electron microscopy, the contribution of the epithelial slit could be smaller than previously believed.
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Affiliation(s)
- Numpong Punyaratabandhu
- Department of Physics, Faculty of Science, Chulalongkorn University, 6th Floor, Mahamakut Building, Payathai Road, Pathumwan, Bangkok 10330, Thailand e-mail:
| | - Pimkhwan Kongoup
- Department of Physics, Faculty of Science, Chulalongkorn University, 6th Floor, Mahamakut Building, Payathai Road, Pathumwan, Bangkok 10330, Thailand e-mail:
| | - Panadda Dechadilok
- Department of Physics, Faculty of Science, Chulalongkorn University, 6th Floor, Mahamakut Building, Payathai Road, Pathumwan, Bangkok 10330, Thailand e-mail:
| | - Pisut Katavetin
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Rama IV Road, Pathumwan, Bangkok 10330, Thailand e-mail:
| | - Wannapong Triampo
- Biophysics Group, Department of Physics, Faculty of Science, Mahidol University, Rama 6, Bangkok 10400, Thailand e-mail:
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13
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Sivertsson E, Friederich-Persson M, Öberg CM, Fasching A, Hansell P, Rippe B, Palm F. Inhibition of mammalian target of rapamycin decreases intrarenal oxygen availability and alters glomerular permeability. Am J Physiol Renal Physiol 2018; 314:F864-F872. [PMID: 28971989 DOI: 10.1152/ajprenal.00033.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
An increased kidney oxygen consumption causing tissue hypoxia has been suggested to be a common pathway toward chronic kidney disease. The mammalian target of rapamycin (mTOR) regulates cell proliferation and mitochondrial function. mTOR inhibitors (e.g., rapamycin) are used clinically to prevent graft rejection. mTOR has been identified as a key player in diabetes, which has stimulated the use of mTOR inhibitors to counter diabetic nephropathy. However, the effect of mTOR inhibition on kidney oxygen consumption is unknown. Therefore, we investigated the effects of mTOR inhibition on in vivo kidney function, oxygen homeostasis, and glomerular permeability. Control and streptozotocin-induced diabetic rats were chronically treated with rapamycin, and the functional consequences were studied 14 days thereafter. In both groups, mTOR inhibition induced mitochondrial uncoupling, resulting in increased total kidney oxygen consumption and decreased intrarenal oxygen availability. Concomitantly, mTOR inhibition induced tubular injury, as estimated from urinary excretion of kidney injury molecule-1 (KIM-1) and reduced urinary protein excretion. The latter corresponded to reduced sieving coefficient for large molecules. In conclusion, mTOR inhibition induces mitochondrial dysfunction leading to decreased oxygen availability in normal and diabetic kidneys, which translates into increased KIM-1 in the urine. Reduced proteinuria after mTOR inhibition is an effect of reduced glomerular permeability for large molecules. Since hypoxia has been suggested as a common pathway in the development of chronic kidney disease, mTOR inhibition to patients with preexisting nephropathy should be used with caution, since it may accelerate the progression of the disease.
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Affiliation(s)
- Ebba Sivertsson
- Division of Integrative Physiology, Department of Medical Cell Biology, Uppsala University , Uppsala , Sweden
| | - Malou Friederich-Persson
- Division of Integrative Physiology, Department of Medical Cell Biology, Uppsala University , Uppsala , Sweden
| | - Carl M Öberg
- Department of Nephrology, Lund University , Lund , Sweden
| | - Angelica Fasching
- Division of Integrative Physiology, Department of Medical Cell Biology, Uppsala University , Uppsala , Sweden
| | - Peter Hansell
- Division of Integrative Physiology, Department of Medical Cell Biology, Uppsala University , Uppsala , Sweden
| | - Bengt Rippe
- Department of Nephrology, Lund University , Lund , Sweden
| | - Fredrik Palm
- Division of Integrative Physiology, Department of Medical Cell Biology, Uppsala University , Uppsala , Sweden
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14
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Dolinina J, Rippe A, Bentzer P, Öberg CM. Glomerular hyperpermeability after acute unilateral ureteral obstruction: effects of Tempol, NOS, RhoA, and Rac-1 inhibition. Am J Physiol Renal Physiol 2018; 315:F445-F453. [PMID: 29465305 DOI: 10.1152/ajprenal.00610.2017] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
It is well known that proteinuria following urinary tract obstruction is mainly of a tubular nature. However, it is unknown whether there are also changes in glomerular permeability. In this study, we compared glomerular sieving coefficients (θ) of polydisperse fluorescein isothiocyanate (FITC)-Ficoll 70/400 following a 120- or 180-min unilateral ureteral obstruction (UUO) in anesthetized Sprague-Dawley rats. Samples were collected from the obstructed kidney at 5, 15, and 30 min postrelease and analyzed by means of high-pressure size-exclusion chromatography. After 120-min UUO, mean θ for Ficoll70Å was increased ( P < 0.01) from 2.2 ± 0.5 × 10-5 (baseline) to 10.6 ± 10 × 10-5 15 min postrelease (highest value). After 180-min UUO, mean θ for Ficoll70Å was further increased ( P < 0.001) from 1.4 ± 0.5 × 10-5 (baseline) to 40 ± 10 × 10-5 at 5 min postrelease (highest value). Administration of a reactive oxygen species (ROS) scavenger (Tempol; 1 mg·kg-1·min-1) partly abrogated the permeability effects following 120-min UUO but not after 180 min. Moreover, administration of the RhoA kinase inhibitor Y-27632, the nitric oxide synthase inhibitor NG-nitro-l-arginine methyl ester, or Rac-1 inhibition did not ameliorate glomerular hyperpermeability following 180-min UUO. We show, for the first time, that acute UUO results in marked elevations in glomerular permeability. In addition, our data suggest a time-dependent pathophysiology of UUO-induced hyperpermeability, where reactive oxygen species generation may play an important role in the early stages.
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Affiliation(s)
- Julia Dolinina
- Department of Nephrology, Clinical Sciences Lund, Lund University , Lund , Sweden
| | - Anna Rippe
- Department of Nephrology, Clinical Sciences Lund, Lund University , Lund , Sweden
| | - Peter Bentzer
- Department of Anesthesiology and Intensive Care, Clinical Sciences Lund, Lund University , Lund , Sweden.,Department of Anesthesia and Intensive Care, Helsingborg Hospital, Helsingborg, Sweden
| | - Carl M Öberg
- Department of Nephrology, Clinical Sciences Lund, Lund University , Lund , Sweden
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15
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Palit S, Yethiraj A. Dynamics and cluster formation in charged and uncharged Ficoll70 solutions. J Chem Phys 2017; 147:074901. [DOI: 10.1063/1.4986366] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Swomitra Palit
- Department of Physics and Physical Oceanography, Memorial University, St. John’s, Newfoundland and Labrador A1B3X7, Canada
| | - Anand Yethiraj
- Department of Physics and Physical Oceanography, Memorial University, St. John’s, Newfoundland and Labrador A1B3X7, Canada
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16
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Öberg CM, Rippe B. Optimizing Automated Peritoneal Dialysis Using an Extended 3-Pore Model. Kidney Int Rep 2017; 2:943-951. [PMID: 29270500 PMCID: PMC5733752 DOI: 10.1016/j.ekir.2017.04.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 03/04/2017] [Accepted: 04/21/2017] [Indexed: 11/20/2022] Open
Abstract
Introduction In the current study, an extended 3-pore model (TPM) is presented and applied to the problem of optimizing automated peritoneal dialysis (APD) with regard to osmotic water transport (UF), small/middle-molecule clearance, and glucose absorption. Methods Simulations were performed for either intermittent APD (IPD) or tidal APD (TPD). IPD was simulated for fill and drain volumes of 2 L, whereas TPD was simulated using a tidal volume of 0.5 L, 1 L, or 1.5 L with full drains and subsequent fills (2 L) occurring after every fifth dwell. A total of 25 cycles for a large number of different dialysate flow rates (DFR) were simulated using 3 different glucose concentrations (1.36%, 2.27%, and 3.86%) and 3 different peritoneal transport types: slow (peritoneal equilibrium test D/Pcrea < 0.6), fast (peritoneal equilibrium test D/Pcrea > 0.8), and average. Solute clearance and UF were simulated to occur during the entire dwell, including both fill and drain periods. Results It is demonstrated that DFRs exceeding ∼ 3 L/h are of little benefit both for UF and small-solute transport, whereas middle-molecule clearance is enhanced at higher DFRs. The simulations predict that large reductions (> 20%) in glucose absorption are possible by using moderately higher DFRs than a standard 6 × 2 L prescription and by using shorter optimized “bi-modal” APD regimens that alternate between a glucose-free solution and a glucose-containing solution. Discussion Reductions in glucose absorption appear to be significant with the proposed regimens for APD; however, further research is needed to assess the feasibility and safety of these regimens.
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Affiliation(s)
- Carl M. Öberg
- Lund University, Skåne University Hospital, Clinical Sciences Lund, Department of Nephrology, Lund, Sweden
- Correspondence: Carl M. Öberg, Department of Nephrology, Skåne University Hospital, S-211 85 Lund, Sweden.Department of Nephrology, Skåne University HospitalS-211 85 LundSweden
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17
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Öberg CM, Groszek JJ, Roy S, Fissell WH, Rippe B. A distributed solute model: an extended two-pore model with application to the glomerular sieving of Ficoll. Am J Physiol Renal Physiol 2017; 314:F1108-F1116. [PMID: 28424207 DOI: 10.1152/ajprenal.00066.2017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
One of the many unresolved questions regarding the permeability of the glomerular filtration barrier is the reason behind the marked difference in permeability between albumin and polysaccharide probe molecules such as Ficoll and dextran of the same molecular size. Although the differences in permeability have been mainly attributed to charge effects, we have previously shown that this would require a highly charged filtration barrier, having a charge density that is ~10 times more than that on the albumin molecule. In this article, the classic two-pore model was extended by introducing size distributions on the solute molecules, making them conformationally flexible. Experimental sieving data for Ficoll from the rat glomerulus and from precision-made silicon nanopore membranes were analyzed using the model. For the rat glomerulus a small-pore radius of 36.2 Å and a geometric standard deviation (gSD) for the Ficoll size-distribution of 1.16 were obtained. For the nanopore membranes, a gSD of 1.24 and a small-pore radius of 43 Å were found. Interestingly, a variation of only ~16% in the size of the polysaccharide molecule is sufficient to explain the difference in permeability between albumin and Ficoll. Also, in line with previous data, the effects of applying a size distribution on the solute molecule are only evident when the molecular size is close to the pore size. Surely there is at least some variation in the pore radii, and, likely, the gSD obtained in the current study is an overestimation of the "true" variation in the size of the Ficoll molecule.
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Affiliation(s)
- Carl M Öberg
- Lund University, Skane University Hospital, Department of Nephrology , Lund , Sweden
| | - Joseph J Groszek
- Nephrology and Hypertension, Vanderbilt University , Nashville, Tennessee
| | - Shuvo Roy
- Bioengineering & Therapeutic Sciences, University of California , San Francisco, California
| | - William H Fissell
- Nephrology and Hypertension, Vanderbilt University , Nashville, Tennessee
| | - Bengt Rippe
- Lund University, Skane University Hospital, Department of Nephrology , Lund , Sweden
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18
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Microproteinuria Predicts Organ Failure in Patients Presenting with Acute Pancreatitis. Dig Dis Sci 2016; 61:3592-3601. [PMID: 27734249 DOI: 10.1007/s10620-016-4335-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Accepted: 09/29/2016] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND AIMS The disease course of acute pancreatitis (AP) ranges from mild and self-limiting to severe inflammation, associated with significant morbidity and mortality. At present, there are no universally accepted and reliable predictors for severity. Microproteinuria has been associated with the presence of systemic inflammatory response syndrome as well as trauma, although its association with AP is not well understood. The aim of this study was to investigate the value of microproteinuria to predict development of organ failure in AP. METHODS Consecutive AP patients were prospectively enrolled. Urine samples were collected upon admission, 12-24 h after admission, and 3 months post-discharge for calculation of urine α1-microglobulin-, albumin-, IgG-, and IgM/creatinine ratios. Data regarding AP etiology, severity, and development of organ failure were registered. RESULTS Overall, 92 AP patients were included (14 % with organ failure; 6 % with severe AP). The α1-microglobulin-, albumin-, and IgG/creatinine ratios correlated with high-sensitivity C-reactive protein 48 h after admission (r = 0.47-0.61, p < 0.001 for all). They were also significantly higher in patients with versus without organ failure (p < 0.05 for all). The α1-microglobulin/creatinine ratio upon admission predicted organ failure [adjusted odds ratio 1.286, 95 % confidence interval (CI) 1.024-1.614] with similar accuracy (AUROC 0.81, 95 % CI 0.69-0.94) as the more complex APACHE II score (AUROC 0.86, 95 % CI 0.70-1.00). CONCLUSION The α1-microglobulin/creatinine ratio upon presentation with AP is related to inflammation and predicts development of organ failure. Further studies are warranted to evaluate its potential usefulness in predicting outcome for AP patients.
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19
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Lubbad L, Öberg CM, Dhanasekaran S, Nemmar A, Hammad F, Pathan JY, Rippe B, Bakoush O. Reduced glomerular size selectivity in late streptozotocin-induced diabetes in rats: application of a distributed two-pore model. Physiol Rep 2015; 3:3/5/e12397. [PMID: 26009635 PMCID: PMC4463827 DOI: 10.14814/phy2.12397] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Microalbuminuria is an early manifestation of diabetic nephropathy. Potential contributors to this condition are reduced glomerular filtration barrier (GFB) size- and charge selectivity, and impaired tubular reabsorption of filtered proteins. However, it was recently reported that no significant alterations in charge selectivity of the GFB occur in early experimental diabetic nephropathy. We here aimed at investigating the functional changes in the GFB in long-term type-1 diabetes in rats, applying a novel distributed two-pore model. We examined glomerular permeability in 15 male Wistar rats with at least 3 months of streptozotocin (STZ)-induced diabetes (blood glucose ∼20 mmol/L) and in age-matched control rats. The changes in glomerular permeability were assessed by determining the glomerular sieving coefficients (θ) for FITC-Ficoll (molecular radius 20–90 Å) using size exclusion HPLC. The values of θ for FITC-Ficoll of radius >50 Å were significantly increased in STZ-diabetic rats compared to age-matched controls (θ for 50–69 Å = 0.001 vs. 0.0002, and θ for 70–90 Å = 0.0007 vs. 0.00006, P < 0.001), while θ for FITC-Ficoll <50 Å tended to be lower in diabetic rats than in controls (θ for 36–49 Å = 0.013 vs. 0.016, ns). According to the distributed two-pore model, there was primarily an increase in macromolecular transport through large pores in the glomerular filter of diabetic rats associated with a loss of small-pore area. Deterioration in the glomerular size selectivity due to an increase in the number and size-spread of large pores, with no changes in the permeability of the small-pore system, represent the major functional changes observed after 3 months of induced experimental diabetes.
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Affiliation(s)
- Loay Lubbad
- Department of Surgery, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Carl M Öberg
- Department of Nephrology, Clinical Sciences Lund, Lund University, Lund, Sweden
| | - Subramanian Dhanasekaran
- Department of Pharmacology and Therapeutics, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Abderrahim Nemmar
- Department of Physiology, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Fayez Hammad
- Department of Surgery, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Javed Y Pathan
- Department of Internal Medicine, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Bengt Rippe
- Department of Nephrology, Clinical Sciences Lund, Lund University, Lund, Sweden
| | - Omran Bakoush
- Department of Internal Medicine, College of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
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20
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Wilkie M. Introduction to point-counterpoint: Mechanisms of glomerular filtration: pores versus an electrical field. Perit Dial Int 2015; 35:4. [PMID: 25700456 DOI: 10.3747/pdi.2014.00325] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Martin Wilkie
- Sheffield Kidney Institute Sheffield Teaching Hospitals NHS Sheffield, South Yorkshire, UK
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21
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Öberg CM, Rippe B. Letter to the Editor: "Can early plasma elimination rate be used to quantify renal clearance of macromolecules?". Am J Physiol Renal Physiol 2015; 308:F164-5. [PMID: 25560050 DOI: 10.1152/ajprenal.00491.2014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Carl M Öberg
- Department of Nephrology, Lund University, Lund, Sweden
| | - Bengt Rippe
- Department of Nephrology, Lund University, Lund, Sweden
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22
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Affiliation(s)
- Bengt Rippe
- Department of Nephrology, Lund University, Lund, Sweden
| | - Carl M Öberg
- Department of Nephrology, Lund University, Lund, Sweden
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23
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Kanwar YS. Continuum of historical controversies regarding the structural-functional relationship of the glomerular ultrafiltration unit. Am J Physiol Renal Physiol 2014; 308:F420-4. [PMID: 25503736 DOI: 10.1152/ajprenal.00640.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Yashpal S Kanwar
- Departments of Pathology and Medicine, Northwestern University, Chicago, Illinois
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