Acute phosphate depletion and in vitro rat proximal tubule injury: Protection by glycine and acidosis

Acute phosphate depletion and in vitro rat proximal tubule injury: Protection by glycine and acidosis.The effects of phosphate (PO4) removal from Krebs Henseleit buffer on freshly isolated rat proximal tubules (rPT) were assessed by measuring Ca2+ uptake (nmol/mg protein), cellular adenosine triphosphate (ATP) (nmol/mg), tissue K+ content (nmol/mg) and lactate dehydrogenase (LDH) as an index of cell integrity. Ca2+ uptake increased by 50% in rPT incubated in zero PO4 medium as compared to control (2.6 ±0.1 vs. 3.9 ±0.19, P < 0.001) and LDH release increased 2.5-fold from 14.2 ±0.6 to 31.6 ±1.6%, P < 0.001. Neither verapamil (200 µM) nor mepacrine (50 µM) reduced Ca2+ uptake or decreased LDH release suggesting that the increased Ca2+ uptake was not occurring through potential operated channels and that phospholipase-induced cell injury was not the cause of increased LDH release. Either glycine (2 mM) or extracellular fluid acidosis (pH 7.06), however, significantly diminished rPT injury and Ca2+ uptake. Specifically, as compared to the increased LDH released in untreated, PO4-depleted rPT, LDH release was diminished significantly by glycine treatment (31.0 ±0.9 vs. 15.5 ±1.6%, P < 0.001) or acidosis (30.3 ±0.04 vs. 19.2 ±0.9%, P < 0.01). Ca2+ uptake did not increase in glycine treated tubules (2.6 ±0.1 vs. 2.8 ±0.2 nmol/mg, NS) or in the presence of acidosis (2.6 ±0.1 vs. 2.97 ±0.17 nmol/mg, NS). ATP concentrations were markedly reduced by PO4 depletion (2.8±0.2 vs. 4.8±0.3 nmol/mg, P < 0.001) and remained at low levels during either acidosis or glycine-induced protection. ATP depletion was accompanied by loss of K+ from rPT and this was only modestly attenuated by either glycine or acidosis. Total cell PO4 was not significantly altered, however, perchloric acid (PCA) extractable free PO4 was reduced significantly (33.3 ±4.5 to 15.9 ±3.5 nmol/mg, P < 0.01). The rPT injury, associated with acute PO4 depletion, may be related to Ca2+ uptake since Ca2+ uptake and LDH release were both attenuated by glycine administration or acidosis

Тепловой насос в системе отопления индивидуального жилого дома

Разработка системы теплоснабжения отдельно стоящего дома с использованием теплового насоса, выбор электрооборудования, исследование режимов работы насосного оборудования и систем управления теплоснабжением.Development of a heat supply system for a detached house using a heat pump, selection of electrical equipment, study of operating modes of pumping equipment and heat supply management systems

Functional tests to guide management in an adult with loss of function of type-1 angiotensin II receptor

BACKGROUND: Genetic loss of function of AGT (angiotensinogen), REN (renin), ACE (angiotensin-converting enzyme), or AGTR1 (type-1 angiotensin II receptor) leads to renal tubular dysgenesis (RTD). This syndrome is almost invariably lethal. Most surviving patients reach stage 5 chronic kidney disease at a young age. METHODS: Here, we report a 28-year-old male with a homozygous truncating mutation in AGTR1 (p.Arg216*), who survived the perinatal period with a mildly impaired kidney function. In contrast to classic RTD, kidney biopsy showed proximal tubules that were mostly normal. During the subsequent three decades, we observed evidence of both tubular dysfunction (hyperkalemia, metabolic acidosis, salt-wasting and a urinary concentrating defect) and glomerular dysfunction (reduced glomerular filtration rate, currently ~30 mL/min/1.73 m(2), accompanied by proteinuria). To investigate the recurrent and severe hyperkalemia, we performed a patient-tailored functional test and showed that high doses of fludrocortisone induced renal potassium excretion by 155%. Furthermore, fludrocortisone lowered renal sodium excretion by 39%, which would have a mitigating effect on salt-wasting. In addition, urinary pH decreased in response to fludrocortisone. Opposite effects on urinary potassium and pH occurred with administration of amiloride, further supporting the notion that a collecting duct is present and able to react to fludrocortisone. CONCLUSIONS: This report provides living proof that even truncating loss-of-function mutations in AGTR1 are compatible with life and relatively good GFR and provides evidence for the prescription of fludrocortisone to treat hyperkalemia and salt-wasting in such patients. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00467-021-05018-7

Modeling complement activation on human glomerular microvascular endothelial cells

Introduction: Atypical hemolytic uremic syndrome (aHUS) is a rare kidney disease caused by dysregulation of the complement alternative pathway. The complement dysregulation specifically leads to damage to the glomerular endothelium. To further understand aHUS pathophysiology, we validated an ex vivo model for measuring complement deposition on both control and patient human glomerular microvascular endothelial cells (GMVECs). Methods: Endothelial cells were incubated with human test sera and stained with an anti-C5b-9 antibody to visualize and quantify complement depositions on the cells with immunofluorescence microscopy.Results: First, we showed that zymosan-activated sera resulted in increased endothelial C5b-9 depositions compared to normal human serum (NHS). The levels of C5b-9 depositions were similar between conditionally immortalized (ci)GMVECs and primary control GMVECs. The protocol with ciGMVECs was further validated and we additionally generated ciGMVECs from an aHUS patient. The increased C5b-9 deposition on control ciGMVECs by zymosan-activated serum could be dose-dependently inhibited by adding the C5 inhibitor eculizumab. Next, sera from five aHUS patients were tested on control ciGMVECs. Sera from acute disease phases of all patients showed increased endothelial C5b-9 deposition levels compared to NHS. The remission samples showed normalized C5b-9 depositions, whether remission was reached with or without complement blockage by eculizumab. We also monitored the glomerular endothelial complement deposition of an aHUS patient with a hybrid complement factor H (CFH)/CFH-related 1 gene during follow-up. This patient had already chronic kidney failure and an ongoing deterioration of kidney function despite absence of markers indicating an aHUS flare. Increased C5b-9 depositions on ciGMVECs were observed in all samples obtained throughout different diseases phases, except for the samples with eculizumab levels above target. We then tested the samples on the patient’s own ciGMVECs. The C5b-9 deposition pattern was comparable and these aHUS patient ciGMVECs also responded similar to NHS as control ciGMVECs. Discussion: In conclusion, we demonstrate a robust and reliable model to adequately measure C5b-9-based complement deposition on human control and patient ciGMVECs. This model can be used to study the pathophysiological mechanisms of aHUS or other diseases associated with endothelial complement activation ex vivo.</p

Acute Treatment Effects on GFR in Randomized Clinical Trials of Kidney Disease Progression

Background: Acute changes in GFR can occur after initiation of interventions targeting progression of CKD. These acute changes complicate the interpretation of long-term treatment effects. Methods: To assess the magnitude and consistency of acute effects in randomized clinical trials and explore factors that might affect them, we performed a meta-analysis of 53 randomized clinical trials for CKD progression, enrolling 56,413 participants with at least one estimated GFR measurement by 6 months after randomization. We defined acute treatment effects as the mean difference in GFR slope from baseline to 3 months between randomized groups. We performed univariable and multivariable metaregression to assess the effect of intervention type, disease state, baseline GFR, and albuminuria on the magnitude of acute effects. Results: The mean acute effect across all studies was 20.21 ml/min per 1.73 m2 (95% confidence interval, 20.63 to 0.22) over 3 months, with substantial heterogeneity across interventions (95% coverage interval across studies, 22.50 to 12.08 ml/min per 1.73 m2). We observed negative average acute effects in renin angiotensin system blockade, BP lowering, and sodium-glucose cotransporter 2 inhibitor trials, and positive acute effects in trials of immunosuppressive agents. Larger negative acute effects were observed in trials with a higher mean baseline GFR. Conclusion: The magnitude and consistency of acute GFR effects vary across different interventions, and are larger at higher baseline GFR. Understanding the nature and magnitude of acute effects can help inform the optimal design of randomized clinical trials evaluating disease progression in CKD

Evidence for renal vasodilation in pre-dialysis patients during correction of anemia by erythropoietin

Evidence for renal vasodilation in pre-dialysis patients during correction of anemia by erythropoietin. Results from animal experiments have suggested that treatment with recombinant human erythropoietin (rHuEPO) causes changes in renal hemodynamics which are detrimental to renal function. Therefore, the effects of correction of the anemia by rHuEPO on glomerular filtration rate (GFR; inulin clearance) and effective renal plasma flow (ERPF; PAH clearance) were studied in eight pre-dialysis patients. The studies were done before (Hct 0.24 ± 0.05 liter/liter) and at 89 ± 19 days after the start of rHuEPO therapy (Hct 0.39 ± 0.03 liter/liter). To further evaluate the effects of ACE inhibition, 25 mg of captopril was given orally after baseline values had been obtained. Baseline GFR, renal blood flow (RBF) and filtration fraction (FF) did not change during rHuEPO therapy. At low hematocrit (Hct) captopril induced a significant increase in ERPF and RBF, and a decrease in MAP. After correction of the hematocrit the blood pressure lowering effect of captopril remained unchanged. However, captopril no longer induced changes in ERPF and RBF. We conclude that the increase in hematocrit had no adverse effects on GFR. The results suggest that changes in hematocrit may influence the effects of ACE inhibition on efferent vascular resistance. Therefore, the hematocrit should be taken into account when evaluating studies on the effects of ACE inhibition in the progression of chronic renal failure

Association of anti-PLA₂R antibodies with outcomes after immunosuppressive therapy in idiopathic membranous nephropathy.

BACKGROUND: The optimal timing and duration of immunosuppressive therapy for idiopathic membranous nephropathy (iMN) have been debated. This study aimed to evaluate whether measuring the antibody against the phospholipase A(2) receptor (PLA(2)R-ab) at start and end of therapy predicts long-term outcome and therefore may inform this debate. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This observational study included all consecutive high-risk patients with progressive iMN observed from 1997 to 2005 and treated with oral cyclophosphamide (CP) or mycophenolate mofetil (MMF) in combination with corticosteroids for 12 months. Patients were prospectively followed, and outcome was ascertained up to 5 years after completion of immunosuppressive therapy. Serum samples were collected before and after completion of therapy. PLA(2)R antibodies were determined retrospectively in stored samples using ELISA. RESULTS: In total, 48 patients (37 men) were included. The median age was 55 years (range, 34–75), and the median serum creatinine level was 1.60 mg/dl (range, 0.98–3.37 mg/dl). Twenty-two patients received MMF and 26 received CP. At baseline, PLA(2)R-abs were present in 34 patients (71%). Baseline characteristics and outcome did not significantly differ between patients negative or positive for PLA(2)R-ab. In PLA(2)R-ab–positive patients, treatment resulted in a rapid decrease of antibodies: median anti–PLA(2)R-ab, 428 U/ml (range, 41–16,260 U/ml) at baseline and 24 U/ml (range, 0–505 U/ml) after 2 months. The PLA(2)R-ab levels at baseline did not predict initial response, but antibody status at end of therapy predicted long-term outcome: After 5 years, 14 of 24 (58%) antibody-negative patients were in persistent remission compared with 0 of 9 (0%) antibody-positive patients (P=0.003). CONCLUSIONS: These data suggest that in PLA(2)R-ab–positive patients, measuring PLA(2)R-abs at the end of therapy predicts the subsequent course