Impact of reference panel composition on scores of script concordance test assessing basic nephrology knowledge in undergraduate medical education

PURPOSE

In the assessment of basic medical knowledge, the composition of the reference panel between specialists and primary care (PC) physicians is a contentious issue. We assessed the effect of panel composition on the scores of undergraduate medical students in a script concordance test (SCT).

METHODS

The scale of an SCT on basic nephrology knowledge was set by a panel of nephrologists or a mixed panel of nephrologists and PC physicians. The results of the SCTs were compared with ANOVA for repeated measurements. Concordance was assessed with Bland and Altman plots.

RESULTS

Forty-five students completed the SCT. Their scores differed according to panel composition: 65.6 ± 9.73/100 points for nephrologists, and 70.27 ± 8.82 for the mixed panel, p < 0.001. Concordance between the scores was low with a bias of -4.27 ± 2.19 and a 95% limit of agreement of -8.96 to -0.38. Panel composition led to a change in the ranking of 71% of students (mean 3.6 ± 2.6 places).

CONCLUSION

The composition of the reference panel, either specialist or mixed, for SCT assessment of basic knowledge has an impact on test results and student rankings.

Indoxyl sulfate inhibits muscle cell differentiation via Myf6/MRF4 and MYH2 downregulation

BACKGROUND

Chronic kidney disease (CKD) is associated with a significant decrease in muscle strength and mass, possibly related to muscle cell damage by uremic toxins. Here, we studied in vitro and in vivo the effect of indoxyl sulfate (IS), an indolic uremic toxin, on myoblast proliferation, differentiation and expression of myogenic regulatory factors (MRF)-myoblast determination protein 1 (MyoD1), myogenin (Myog), Myogenic Factor 5 (Myf5) and myogenic regulatory factor 4 (Myf6/MRF4)-and expression of myosin heavy chain, Myh2.

METHODS

C2C12 myoblasts were cultured in vitro and differentiated in myotubes for 7 days in the presence of IS at a uremic concentration of 200 µM. Myocytes morphology and differentiation was analyzed after hematoxylin-eosin staining. MRF genes' expression was studied using reverse transcription polymerase chain reaction in myocytes and 5/6th nephrectomized mice muscle. Myf6/MRF4 protein expression was studied using enzyme-linked immunosorbent assay; MYH2 protein expression was studied using western blotting. The role of Aryl Hydrocarbon Receptor (AHR)-the cell receptor of IS-was studied by adding an AHR inhibitor into the cell culture milieu.

RESULTS

In the presence of IS, the myotubes obtained were narrower and had fewer nuclei than control myotubes. The presence of IS during differentiation did not modify the gene expression of the MRFs Myf5, MyoD1 and Myog, but induced a decrease in expression of Myf6/MRF4 and MYH2 at the mRNA and the protein level. AHR inhibition by CH223191 did not reverse the decrease in Myf6/MRF4 mRNA expression induced by IS, which rules out the implication of the ARH genomic pathway. In 5/6th nephrectomized mice, the Myf6/MRF4 gene was down-regulated in striated muscles.

CONCLUSION

In conclusion, IS inhibits Myf6/MRF4 and MYH2 expression during differentiation of muscle cells, which could lead to a defect in myotube structure. Through these new mechanisms, IS could participate in muscle atrophy observed in CKD.

Innovations thérapeutiques dans la prise en charge de l’anémie de la maladie rénale chronique Therapeutic innovations in the management of chronic kidney disease-associated anemia

Anemia is a common complication of chronic kidney disease (CKD). The insufficient erythropoietin (EPO) production by the kidneys and iron deficiency are the main causes. Iron supplementation and the administration of recombinant EPO are the main treatment modalities. New iron formulations that can be administered orally, intravenously or directly via the dialysate have recently been developed to improve efficacy and tolerance. Ferric citrate administered orally can effectively corrects anemia in case of iron deficiency and in addition chelate phosphate in the gut lumen. Ferric carboxymaltose allows intravenous administration of larger doses given less frequently. Ferric pyrophosphate citrate administered directly via the dialysate allows the compensation of iron losses during the hemodialysis session. HIF-prolyl-hydroxylase inhibitors are a new therapeutic class of erythropoiesis-stimulating agents. Orally administered, they act by stabilizing the HIF transcription factor involved in the initiation of erythropoietin production by hypoxia. Several clinical studies have recently evaluated these new molecules in comparison with recombinant EPO. In CKD patients not yet on dialysis or undergoing dialysis therapy non-inferiority in correcting anemia has been demonstrated compared with recombinant EPO. The decrease in circulating hepcidin they induce appears greater than that induced by injectable recombinant EPO. Presently available reports on the safety of HIF-prolyl-hydroxylase inhibitors are reassuring but need to be confirmed in longer-term studies of larger size. © 2022 Published by Elsevier Masson SAS on behalf of Société francophone de néphrologie, dialyse et transplantation.

Mechanisms of myostatin and activin A accumulation in chronic kidney disease

BACKGROUND

Myostatin and activin A induce muscle wasting by activating the ubiquitin proteasome system and inhibiting the Akt/mTOR pathway. In chronic kidney disease (CKD), myostatin and activin A plasma concentrations are increased, but it is not clear if there is an increased production or a decreased renal clearance.

METHODS

We measured myostatin and activin A concentrations in 232 CKD patients and studied their correlation with estimated glomerular filtration rate (eGFR). We analyzed the myostatin gene (MSTN) expression in muscle biopsies of hemodialysis (HD) patients. We then measured circulating myostatin and activin A in plasma and the Mstn and Inhba expression in muscles, kidney, liver and heart of two CKD mice models (adenine and 5/6th nephrectomy models). Finally, we analyzed whether the uremic toxin indoxyl sulfate (IS) increased Mstn expression in mice and cultured muscle cells.

RESULTS

In patients, myostatin and activin A were inversely correlated with eGFR. MSTN expression was lower in HD patients' muscles (vastus lateralis) than in controls. In mice with CKD, myostatin and activin A blood concentrations were increased. Mstn was not up-regulated in CKD mice tissues. Inha was up-regulated in kidney and heart. Exposure to IS did not induce Mstn up-regulation in mice muscles and in cultured myoblasts and myocytes.

CONCLUSION

During CKD, myostatin and activin A blood concentrations are increased. Myostatin is not overproduced, suggesting only an impaired renal clearance, but activin A is over produced in kidney and heart. We propose to add myostatin and activin A to the list of uremic toxins.

Kidney Histopathology Can Predict Kidney Function in ANCA-Associated Vasculitides with Acute Kidney Injury Treated with Plasma Exchanges

BACKGROUND

Data from the PEXIVAS trial challenged the role of plasma exchange (PLEX) in ANCA-associated vasculitides (AAV). We aimed to describe kidney biopsy from patients with AAV treated with PLEX, evaluate whether histopathologic findings could predict kidney function, and identify which patients would most benefit from PLEX.

METHODS

We performed a multicenter, retrospective study on 188 patients with AAV and AKI treated with PLEX and 237 not treated with PLEX. The primary outcome was mortality or KRT at 12 months (M12).

RESULTS

No significant benefit of PLEX for the primary outcome was found. To identify patients benefitting from PLEX, we developed a model predicting the average treatment effect of PLEX for an individual depending on covariables. Using the prediction model, 223 patients had a better predicted outcome with PLEX than without PLEX, and 177 of them had >5% increased predicted probability with PLEX compared with without PLEX of being alive and free from KRT at M12, which defined the PLEX-recommended group. Risk difference for death or KRT at M12 was significantly lower with PLEX in the PLEX-recommended group (-15.9%; 95% CI, -29.4 to -2.5) compared with the PLEX not recommended group (-4.8%; 95% CI, 14.9 to 5.3). Microscopic polyangiitis, MPO-ANCA, higher serum creatinine, crescentic and sclerotic classes, and higher Brix score were more frequent in the PLEX-recommended group. An easy to use score identified patients who would benefit from PLEX. The average treatment effect of PLEX for those with recommended treatment corresponded to an absolute risk reduction for death or KRT at M12 of 24.6%.

CONCLUSIONS

PLEX was not associated with a better primary outcome in the whole study population, but we identified a subset of patients who could benefit from PLEX. However, these findings must be validated before utilized in clinical decision making.

Rituximab for recurrence of primary focal segmental glomerulosclerosis after kidney transplantation: Results of a nationwide study

Rituximab (RTX) therapy for primary focal segmental glomerulosclerosis recurrence after kidney transplantation (KT) has been extensively debated. We aimed to assess the benefit of adding RTX to plasmapheresis (PP), corticosteroids, and calcineurin inhibitors (standard of care, SOC). We identified 148 adult patients who received KT in 12/2004-12/2018 at 21 French centers: 109 received SOC (Group 1, G1), and 39 received immediate RTX along with SOC (Group 2, G2). In G1, RTX was introduced after 28 days of SOC in the event of failure (G1a, n = 19) or PP withdrawal (G1b, n = 12). Complete remission (CR) was achieved in 46.6% of patients, and partial remission (PR) was achieved in 33.1%. The 10-year graft survival rates were 64.7% and 17.9% in responders and nonresponders, respectively. Propensity score analysis showed no difference in CR+PR rates between G1 (82.6%) and G2 (71.8%) (p = .08). Following the addition of RTX (G1a), 26.3% of patients had CR, and 31.6% had PR. The incidence of severe infections was similar between patients treated with and without RTX. In multivariable analysis, infection episodes were associated with hypogammaglobulinemia <5 g/L. RTX could be used in cases of SOC failure or remission for early discontinuation of PP without increasing the risk of infection.

Day and night changes in energy expenditure of patients on automated peritoneal dialysis

RATIONALE

Automated peritoneal dialysis (APD) treatment for end-stage kidney disease affords patients a degree of autonomy in everyday life. Clinical investigations of their energy expenditure (EE) are usually based on resting EE, which could mask day and night variations in EE. The aim of this study, therefore, was to compare the components of EE in APD patients and healthy control (C) subjects.

MATERIAL AND METHOD

Patients treated with APD for more than 3 months were compared with C volunteers matched for age and lean body mass (LBM). Biochemical analyses were performed and body composition was determined by DEXA to adjust EE to LBM. Total EE, its different components and respiratory quotients (RQ) were measured by a gas exchange method in calorimetric chambers. Spontaneous total and activity-related EE (AEE) were also measured in free-living conditions over 4 days by a calibrated accelerometer and a heart rate monitor.

RESULTS

APD (n = 7) and C (n = 7) patients did not differ in age and body composition. REE did not differ between the two groups. However, prandial increase in EE adjusted for dietary energy intake was higher in APD patients (+57.5 ± 12.71 kcal/h) than in C subjects (+33.8 ± 10.5 kcal/h, p = 0.003) and nocturnal decrease in EE tended to be lower in APD patients undergoing dialysis sessions (- 4.53 ± 8.37 kcal/h) than in subjects (- 11.8 ± 7.69 kcal/h, p = 0.059). Resting RQ (0.91 ± 0.09 vs 0.81 ± 0.04, p = 0.032) and nocturnal RQ (0.91 ± 0.09 vs 0.81 ± 0.04, p = 0.032) were significantly higher in APD patients, indicating a preferential use of glucose substrate potentially absorbed across the peritoneum. AEE was lower in APD patients (595.9 ± 383.2 kcal/d) than in C subjects (1205.2 ± 370.5 kcal/d, p = 0.011). In contrast, energy intakes were not significantly different (1986 ± 465 vs 2083 ± 377 kcal/d, p = 0.677).

CONCLUSION

Although the two groups had identical resting EE, APD patients had a higher prandial increase in EE, a lower activity-related EE and higher resting and nocturnal RQ than healthy subjects.

Management of Immunosuppression After Kidney Transplant Failure: Effect on Patient Sensitization

BACKGROUND

Immunosuppressive treatment is often interrupted in the first months following kidney transplant failure (KTF) to limit side effects. The aim of this study was to assess the effect of prolonged treatment (PT) of more than 3 months' duration after KTF on HLA sensitization and treatment tolerance.

METHODS

We performed a retrospective observational study involving 119 patients with KTF in 3 French kidney transplant centers between June 2007 and June 2017. Sensitization was defined as the development of HLA donor-specific antibodies (DSA).

RESULTS

In the PT group receiving calcineurin inhibitor (CNI) treatment, 30 of 52 patients (57.7%) were sensitized vs 52 of 67 patients (77.6%) who had early cessation of treatment (P = .02). The results were confirmed by multivariate analysis (odds ratio [OR] = 0.39, 95% confidence interval [CI] [0.16; 0.98], P = .04). The development of de novo DSAs after CNI treatment (n = 63/90 [70.0%]) was significantly more frequent than during CNI treatment, (n = 18/52 [34.6%], P = .01). Panel-reactive antibody ≥85% was lower in the PT group in multivariate analysis (OR = 0.28, 95% CI [0.10; 0.78], P = .02). No differences in the rates of infection, cardiovascular complications, neoplasia, and deaths were observed between the 2 groups. In multivariate analysis, continuation of corticosteroid treatment had no influence on sensitization but was associated with a higher rate of infection (OR = 2.66, 95% CI [1.09; 6.46], P = .03).

CONCLUSION

Maintenance of CNI treatment after return to dialysis in patients requesting a repeat transplant could avoid the development of anti-HLA sensitization with a good tolerance.

Circulating 20S proteasome for assessing protein energy wasting syndrome in hemodialysis patients

Protein energy wasting (PEW) including muscle atrophy is a common complication in chronic hemodialysis patients. The ubiquitin proteasome system (UPS) is the main proteolytic system causing muscle atrophy in chronic kidney disease and proteasome 20S is the catalytic component of the UPS. Circulating proteasome 20S (c20S proteasome) is present in the blood and its level is related to disease severity and prognosis in several disorders. We hypothesized that c20S proteasome could be related with muscle mass, other PEW criteria and their evolution in hemodialysis patients. Stable hemodialysis patients treated at our center for more than 3 months were followed over 2 years. C20S proteasome assay was performed at baseline. Biological and clinical data were collected, muscle mass was assessed by multi-frequency bio-impedancemetry, and nutritional scores were calculated at baseline, 1 year and 2 years. Hospitalizations and mortality data were collected over the 2 years. Forty-nine patients were included. At baseline, the c20S proteasome level was 0.40[0.26–0.55] μg/ml. Low muscle mass as defined by a lean tissue index (LTI) < 10th in accordance with the International Society of Renal Nutrition and Metabolism guidelines was observed in 36% and PEW in 62%. Increased c20S proteasome levels were related with LTI at baseline (R = 0.43, p = 0.004) and with its 2 year-variation (R = -0.56, p = 0.003). Two-year survival rate was not different between higher and lower c20S proteasome values (78.9 vs 78.4%, p = 0.98 log-rank test). C20S proteasome is not a good marker for assessing nutritional status in hemodialysis patients and predicting patient outcomes.

Cobalamin c deficiency associated with antifactor h antibody-associated hemolytic uremic syndrome in a young adult

Background

Thrombotic microangiopathy (TMA) syndromes are characterized by the association of hemolytic anemia, thrombocytopenia and organ injury due to arteriolar and capillary thrombosis.

Case presentation

We report the first case of adult onset cobalamin C (Cbl C) disease associated with anti-factor H antibody-associated hemolytic uremic syndrome (HUS).

A 19-year-old woman was admitted to the nephrology department owing to acute kidney failure, proteinuria, and hemolytic anemia with schizocytes.

TMA was diagnosed and plasma exchanges were started in emergency.

Exhaustive analyses showed 1) circulating anti factor H antibody and 2) hyperhomocysteinemia, hypomethioninemia and high levels of methylmalonic aciduria pointing towards Clb C disease. Cbl C disease has been confirmed by methylmalonic aciduria and homocystinuria type C protein gene sequencing revealing two heterozygous pathogenic variants.

The kidney biopsy showed 1) intraglomerular and intravascular thrombi 2) noticeable thickening of the capillary wall with a duplication aspect of the glomerular basement membrane and a glomerular capillary wall IgM associated with Cbl C disease related TMA.

We initiated treatment including hydroxycobalamin, folinic acid, betaine and levocarnitine and Eculizumab. Rituximab infusions were performed allowing a high decrease in anti-factor H antibody rate.

Six month after the disease onset, Eculizumab was weaning and vitaminotherapy continued. Outcome was favorable with a dramatic improvement in kidney function.

Conclusion

TMA with renal involvement can have a complex combination of risk factors including anti-FH autoantibody in the presence of cblC deficiency.

Evaluation of the efficacy of an interdialytic "ethanol 40% v/v - enoxaparin 1000 U/mL" lock solution to prevent tunnelled catheter infections in chronic hemodialysis patients: a multi-centre, randomized, single blind, parallel group study

BACKGROUND

Tunnelled dialysis catheter (TC) infections are a major health complication and are associated with increased antibiotic consumption, hospital stays, health costs and mortality. Experimental data provide evidence that Ethenox, a mixture of enoxaparine 1000 U/mL in 40% v/v ethanol, could be a promising lock solution. The aim of the study is to compare an interdialytic lock solution of Ethenox with reference lock solutions, unfractionated heparin (UFH) or citrate 4% for the prevention of TCI in hemodialysis patients.

METHOD

This study will monitor a multicentre, prospective, single blind, randomized, controlled, parallel group trial. The main inclusion criteria are patients > 18 years old with end-stage renal disease, treated with chronic hemodialysis/hemodiafiltration three times a week, with incident or prevalent non-impregnated internal jugular TCs inserted for at least 2 weeks and able to give informed consent. Exclusion criteria are TCI in the previous 4 weeks and anti-infective treatment for TCI in the previous 2 weeks. Patients will be randomized to receive either study treatment Ethenox in the intervention group or reference solutions in the control group, unfractionated heparin (UFH) or citrate 4% w/v according to usual practice. The primary outcome measure will be time to first TCIs assessed by an endpoint adjudication committee blinded to the study arm according to predefined criteria. Patients will receive the study treatment for up to 12 months. Intention-to-treat analysis of the primary endpoint will be performed with a marginal Cox proportional hazard model. Prospective power calculations indicate that the study will have 90% statistical power to detect a clinical significant two-fold increase in median infection-free survival if 200 patients are recruited into each arm over a period of 24 months.

DISCUSSION

Firm evidence of the efficacy of the Ethenox lock in preventing TCI could be of major clinical benefit for patients. The results of this study will allow the development of new guidelines based on a high level of evidence.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03083184 , date of registration March 17 2017 and European Clinical Trials Database Identifier: EudraCT 2016-A00180-51), date of registration July 11 2016.

Muscle wasting in patients with end-stage renal disease or early-stage lung cancer: common mechanisms at work

BACKGROUND

Loss of muscle mass worsens many diseases such as cancer and renal failure, contributes to the frailty syndrome, and is associated with an increased risk of death. Studies conducted on animal models have revealed the preponderant role of muscle proteolysis and in particular the activation of the ubiquitin proteasome system (UPS). Studies conducted in humans remain scarce, especially within renal deficiency. Whether a shared atrophying programme exists independently of the nature of the disease remains to be established. The aim of this work was to identify common modifications at the transcriptomic level or the proteomic level in atrophying skeletal muscles from cancer and renal failure patients.

METHODS

Muscle biopsies were performed during scheduled interventions in early-stage (no treatment and no detectable muscle loss) lung cancer (LC), chronic haemodialysis (HD), or healthy (CT) patients (n = 7 per group; 86% male; 69.6 ± 11.4, 67.9 ± 8.6, and 70.2 ± 7.9 years P > 0.9 for the CT, LC, and HD groups, respectively). Gene expression of members of the UPS, autophagy, and apoptotic systems was measured by quantitative real-time PCR. A global analysis of the soluble muscle proteome was conducted by shotgun proteomics for investigating the processes altered.

RESULTS

We found an increased expression of several UPS and autophagy-related enzymes in both LC and HD patients. The E3 ligases MuRF1 (+56 to 78%, P < 0.01), MAFbx (+68 to 84%, P = 0.02), Hdm2 (+37 to 59%, P = 0.02), and MUSA1/Fbxo30 (+47 to 106%, P = 0.01) and the autophagy-related genes CTPL (+33 to 47%, P = 0.03) and SQSTM1 (+47 to 137%, P < 0.01) were overexpressed. Mass spectrometry identified >1700 proteins, and principal component analysis revealed three differential proteomes that matched to the three groups of patients. Orthogonal partial least square discriminant analysis created a model, which distinguished the muscles of diseased patients (LC or HD) from those of CT subjects. Proteins that most contributed to the model were selected. Functional analysis revealed up to 238 proteins belonging to nine metabolic processes (inflammatory response, proteolysis, cytoskeleton organization, glucose metabolism, muscle contraction, oxidant detoxification, energy metabolism, fatty acid metabolism, and extracellular matrix) involved in and/or altered by the atrophying programme in both LC and HD patients. This was confirmed by a co-expression network analysis.

CONCLUSIONS

We were able to identify highly similar modifications of several metabolic pathways in patients exhibiting diseases with different aetiologies (early-stage LC vs. long-term renal failure). This strongly suggests that a common atrophying programme exists independently of the disease in human.

No impact of disseminated intravascular coagulation in kidney donors on long-term kidney transplantation outcome: A multicenter propensity-matched study

The diagnosis of disseminated intravascular coagulation (DIC) is often considered to be a contraindication to organ donation. The aim of this study was to evaluate the impact of DIC+ donors on kidney recipient (KR) evolution. We identified 169 KRs with DIC+ donation after brain death donors between January 1996 and December 2012 in 6 French transplant centers. Individuals were matched using propensity scores to 338 recipients with DIC- donors according to donor age and sex, whether expanded criteria for the donor existed, graft year, and transplantation center. After kidney transplantation, delayed graft function was observed in 28.1% of DIC+ KRs and in 22.8% of DIC- KRs (NS). Renal allograft survival at 1, 5, and 10 years was 94.5%, 89.3%, and 73.9% and 96.2%, 90.8%, and 81.3% in DIC+ KRs and DIC- KRs, respectively (NS). The median estimated glomerular filtration rate (eGFR) was similar between DIC+ and DIC- KRs at 3 months, 1 year, and 10 years: 45.9 vs 48.1 mL/min, 42.1 vs 43.1 mL/min, and 33.9 vs 38.1 mL/min, respectively. Delayed calcineurin inhibitor introduction or induction had no impact on delayed graft function rate or eGFR evolution at 10 years after transplantation in DIC+ KRs. Donor DIC did not seem to affect initial outcome, long-term graft function, or allograft survival.

Evolution of chronic kidney disease after surgical aortic valve replacement or transcatheter aortic valve implantation

BACKGROUND

Immediate improvement in kidney function has been reported after surgical aortic valve replacement or transcatheter aortic valve implantation. Long-term data, however, are not available.

AIM

To assess the evolution of kidney function in chronic kidney disease stage 3b-5, 1 year after surgical aortic valve replacement or transcatheter aortic valve implantation.

METHODS

All patients with chronic kidney disease stage 3b-5 undergoing surgical aortic valve replacement or transcatheter aortic valve implantation for aortic stenosis in a single centre were included. Kidney function was assessed 1 year postprocedure. Improvement or deterioration in estimated glomerular filtration rate was defined by an increase or decrease of 5mL/min/1.73 m², respectively.

RESULTS

Overall, 127 procedures were analysed (54 surgical aortic valve replacements and 73 transcatheter aortic valve implantations). Kidney function improved in 51% of patients at 1 year (45% of the surgical aortic valve replacement group versus 57% of the transcatheter aortic valve implantation group; P=0.21), and deteriorated in only 14% of patients at 1 year (18% of the surgical aortic valve replacement group versus 10% of the transcatheter aortic valve implantation group; P=0.22). Almost a quarter of patients (23%) had an improvement in estimated glomerular filtration rate of>15mL/min/1.73 m², and this was consistent at later follow-up. Few patients went onto chronic dialysis at 1 year (three after surgical aortic valve replacement and one after transcatheter aortic valve implantation). Acute kidney injury was an independent prognostic factor for long-term deterioration in kidney function (odds ratio 2.1, 95% confidence interval 1.4-3.6; P=0.006).

CONCLUSION

Aortic valve replacement, whether by surgical aortic valve replacement or transcatheter aortic valve implantation, improved estimated glomerular filtration rate at 1 year in more than half of patients with chronic kidney disease stage 3b-5.

Renal Transplant in Obese Patients and Impact of Weight Loss Before Surgery on Surgical and Medical Outcomes: A Single-Center Cohort Study

OBJECTIVES

Previous studies have linked obesity to poor outcomes in renal transplant recipients, prompting many transplant centers to encourage weight loss pretransplant in obese patients. Here, we performed a single-center retrospective study to assess the effects of weight loss on graft and patient outcomes.

MATERIALS AND METHODS

Data from 893 renal transplant recipients at our center from 2007 to 2011 were analyzed. First, renal transplant recipients with a history of obesity before transplant (42%) were compared with nonobese patients. Second, in the obese group, renal transplant recipients with significant weight loss (> 10%) before transplant were compared with other obese renal transplant recipients without significant weight loss.

RESULTS

Renal transplant recipients were predominantly white, with 74% having undergone living-donor transplant. Obese patients were older (56.6 vs 46.7 y old) and had more comorbidities and more surgical complications, in particular wound complications and incisional hernias, posttransplant than nonobese patients (14.7 vs 5.5%, respectively). Patient and graft survival rates were similar to those in nonobese patients. In the obese group, patient characteristics and medical or surgical complications after transplant did not differ between those with or without significant weight loss. However, obese patient and graft survival rates were lower in patients with weight loss than in obese patients without weight loss.

CONCLUSIONS

In our study, weight loss before transplant surgery in obese patients had no influence on surgical outcomes but was associated with a higher mortality rate. A prospective assessment of the impact of weight loss before surgery is needed to establish its usefulness.

Erratum: Polge, C., et al. UBE2E1 Is Preferentially Expressed in the Cytoplasm of Slow-Twitch Fibers and Protects Skeletal Muscles from Exacerbated Atrophy upon Dexamethasone Treatment. Cells 2018, 7, 214

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Ischemia reperfusion injury in kidney transplantation: A case report

RATIONALE

Kidney transplantation is considered the best treatment for patients with end stage renal disease. Ischemia- reperfusion injury (IRI) is an evitable event after deceased donor transplantation and influences short term and long term graft outcome. Few data on IRI's histology in the setting of kidney transplantation are available in the literature despite its frequency and its severity.

PATIENT CONCERNS

A 64-year-old patient was admitted for his 1st kidney transplantation. There were no pre-existing immunization. The surgery proceeded without complications; with cold ischemia estimated at 37 h 50 min and warm ischemia at 44 min. The immunosuppression protocol was as follows: induction by thymoglobulins, mycophelonate mofetil, corticosteroids. Few hours after transplantation, the patient remained anuric and the biological assessment highlighted in addition to renal failure, hyperlactatemia at 5 mmol/L and a high increase in lactate deshydrogenase (LDH) at 5239 U/L. An abdominopelvic angio-scanner was performed urgently to eliminate the hypothesis of thrombosis of the artery or vein of the graft. A kidney biopsy was performed the day after the transplant and revealed massive lesions of acute tubular necrosis including apoptosis, autophagy-associated cell death, and necrosis. Microvascular dysfunction with increased vascular permeability and endothelial cell inflammation were also present. Activation of coagulation is represented by thrombi in the lumens of the glomerular capillaries.

DIAGNOSIS

The diagnosis was ischemia reperfusion injury responsible for delayed graft function (DGF).

INTERVENTIONS

Immunosuppressive regimen was delayed use of calcineurin inhibitors, mycophenolate mofetil, and corticosteroids.

OUTCOMES

At 1 year post transplant, the patient has a renal autonomy with a graft function stable and physiological proteinuria.

LESSONS

The main clinical consequences of IRI in kidney transplant are DGF, acute and chronic graft rejection, and chronic graft dysfunction. Reducing IRI is one of the most relevant challenge in kidney transplantation.

Mathematical model of calcium exchange during haemodialysis using a citrate containing dialysate

Calcium has two important roles in haemodialysis. It participates in the activation of blood coagulation and calcium intakes have a major impact on patient mineral and bone metabolism. The aim of this article is to propose a mathematical model for calcium ions concentration in a dialyzer during haemodialysis using a citrate dialysate. The model is composed of two elements. The first describes the flows of blood and dialysate in a dialyzer fibre. It was obtained by asymptotic analysis and takes into account the anisotropy of the fibres forming a dialyzer. Newtonian and non-Newtonian blood rheologies were tested. The second part of the model predicts the evolution of the concentration of five chemical species present in these fluids. The fluid velocity field drives the convective part of a convection-reaction-diffusion system that models the exchange of free and complexed calcium. We performed several numerical experiments to calculate the free calcium concentration in the blood in a dialyzer using dialysates with or without citrate. The choice of blood rheology had little effect on the fluid velocity field. Our model predicts that only a citrate based dialysate without calcium can decrease free calcium concentration at the blood membrane interface low enough to inhibit blood coagulation. Moreover for a given calcium dialysate concentration, adding citrate to the dialysate decreases total calcium concentration in the blood at the dialyzer outlet. This decrease of the calcium concentration can be compensated by infusing in the dialyzed blood a quantity of calcium computed from the model.

A muscle-specific MuRF1-E2 network requires stabilization of MuRF1-E2 complexes by telethonin, a newly identified substrate

BACKGROUND

Muscle wasting is observed in the course of many diseases and also during physiological conditions (disuse, ageing). Skeletal muscle mass is largely controlled by the ubiquitin-proteasome system and thus by the ubiquitinating enzymes (E2s and E3s) that target substrates for subsequent degradation. MuRF1 is the only E3 ubiquitin ligase known to target contractile proteins (α-actin, myosins) during catabolic situations. However, MuRF1 depends on E2 ubiquitin-conjugating enzymes for ubiquitin chain formation on the substrates. MuRF1-E2 couples are therefore putative targets for preventing muscle wasting.

METHODS

We focused on 14 E2 enzymes that are either expressed in skeletal muscle or up-regulated during atrophying conditions. In this work, we demonstrated that only highly sensitive and complementary interactomic approaches (surface plasmon resonance, yeast three-hybrid, and split green fluorescent protein) allowed the identification of MuRF1 E2 partners.

RESULTS

Five E2 enzymes physically interacted with MuRF1, namely, E2E1, E2G1, E2J1, E2J2, and E2L3. Moreover, we demonstrated that MuRF1-E2E1 and MuRF1-E2J1 interactions are facilitated by telethonin, a newly identified MuRF1 substrate. We next showed that the five identified E2s functionally interacted with MuRF1 since, in contrast to the non-interacting E2D2, their co-expression in HEK293T cells with MuRF1 led to increased telethonin degradation. Finally, we showed that telethonin governed the affinity between MuRF1 and E2E1 or E2J1.

CONCLUSIONS

We report here the first MuRF1-E2s network, which may prove valuable for deciphering the precise mechanisms involved in the atrophying muscle programme and for proposing new therapeutical approaches.

[Collapsing focal segmental glomerulosclerosis induced by cytomegalovirus: A case report]

Focal segmental glomerulosclerosis (FSGS) is a common cause of nephrotic syndrome in child and adult. The collapsing forms are of poor renal prognosis and are usually secondary to viral infections with, first and foremost, the human immunodeficiency virus. Among other viral etiologies, cytomegalovirus (CMV) is an uncommon cause. We report a case of a 32years-old patient with collapsing focal segmental glomerulosclerosis induced by cytomegalovirus with initial acute renal failure and proteinuria at 12.4g/24h. The treatment associated ganciclovir during 7days followed by valganciclovir during 14days and steroids at 1mg/kg/day. Renal function improved and proteinuria decreased with this treatment. Proteinuria increase again 3weeks after valganciclovir discontinuation while CMV Polymerase chain reaction (PCR) was positive. Therefore, valganciclovir has been resumed allowing renal function normalization and decrease in proteinuria to 4g/24h after negative CMVPCR assay after 15weeks. Anti-CMV therapy combined with steroids seems to provide a renal response in case of FSGS induced by CMV even if long-term prognosis stays uncertain.

Bile Cast Nephropathy Caused by Obstructive Cholestasis

Acute kidney injury (AKI) is a major complication in patients with liver disease. Although hepatorenal syndrome is frequently involved, bile cast nephropathy, characterized by tubular bile cast formation, has been scarcely described in the setting of severe liver failure. Few renal histology studies are available in these patients. We describe a case of bile cast nephropathy in a patient with obstructive cholestasis caused by stones in the common bile duct. The kidney biopsy confirmed this diagnosis, with several green casts in tubular lumens, tubular injury, and bilirubin composition of the tubular casts with Hall stain. The patient had no confounding cause of kidney failure, and complete kidney recovery followed removal of the bile duct obstruction. This case shows that severe cholestasis is sufficient to cause AKI, and that AKI can be reversible after treatment of the biliary obstruction.

Anti-TNFα therapy for chronic inflammatory disease in kidney transplant recipients: Clinical outcomes

Anti-tumor necrosis factor-α (TNFα) therapy has improved the prognosis of many chronic inflammatory diseases. It appears to be well-tolerated by liver-transplant patients. However, their use and their safety in kidney-transplant patients have yet to be determined.In this retrospective study, we identified 16 adult kidney-transplant patients aged 46.5 years (34-51.8) who received anti-TNFα therapy from 7 kidney transplantation centers. The indications for this treatment included: chronic inflammatory bowel disease (n = 8), inflammatory arthritis (n = 5), AA amyloidosis (n = 1), psoriasis (n = 1), and microscopic polyangiitis (n = 1).Anti-TNFα therapies resulted in a clinical response in 13/16 patients (81%). Estimated glomerular filtration rates (MDRD-4) were similar on day 0 and at 24 months (M24) after anti-TNFα treatment had been initiated (41 [12-55] and 40 [21-53] mL/min/1.73 m, respectively). Two allograft losses were observed. The 1st case was due to antibody-mediated rejection (M18), while the 2nd was the result of AA amyloidosis recurrence (M20). There were several complications: 8 patients (50%) developed 23 serious infections (18 bacterial, 4 viral, and 1 fungal) and 4 developed cancer. Five patients died (infection n = 2, cardiac AA amyloidosis n = 1, intraalveolar hemorrhage following microscopic polyangiitis n = 1, and acute respiratory distress syndrome n = 1). On univariate analysis, recipient age associated with death (P = 0.009) and infection development (P = 0.06).Using anti-TNFα therapies, remission can be achieved in chronic inflammatory diseases in kidney-transplant patients. However, concommitant anti-TNFα and immunosuppresive therapies must be used with caution due to the high risk of infection, particularly after the age of 50.

Upregulation of MuRF1 and MAFbx participates to muscle wasting upon gentamicin-induced acute kidney injury

Acute Kidney Injury (AKI) is frequently encountered in hospitalized patients where it is associated with increased mortality and morbidity notably affecting muscle wasting. Increased protein degradation has been shown to be the main actor of AKI-induced muscle atrophy, but the proteolytic pathways involved are poorly known. The Ubiquitin Proteasome System (UPS) is almost systematically activated in various catabolic situations, and the E3 ligases MuRF1 and MAFbx are generally up regulated in atrophying muscles. We hypothesized that the UPS may be one of the main actors in catabolic skeletal muscles from AKI animals. We used gentamicin-induced acute kidney disease (G-AKI) in rats fed a high protein diet to promote acidosis. We first addressed the impact of G-AKI in the development of mild catabolic conditions. We found that both muscle atrophy and UPS activation were induced with the development of G-AKI. In addition, the phasic muscles were more sensitive to 7-days G-AKI (-11 to -17%, P<0.05) than the antigravity soleus muscle (-11%, NS), indicating a differential impact of AKI in the musculature. We observed an increased expression of the muscle-specific E3 ligases MuRF1 and MAFbx in phasic muscles that was highly correlated to the G-AKI severity (R²=0.64, P<0.01 and R²=0.71, P<0.005 respectively). Conversely, we observed no variation in the expression of three other E3 ligases (Nedd4, Trim32 and Fbxo30/MUSA1). Altogether, our data indicate that MuRF1 and MAFbx are sensitive markers and potential targets to prevent muscle atrophy during G-AKI.

Daily urinary urea excretion to guide intermittent hemodialysis weaning in critically ill patients

Background

There are no easily available markers of renal recovery to guide intermittent hemodialysis (IHD) weaning. The aim of this study was to identify markers for IHD weaning in critically ill patients with acute kidney injury (AKI).

Methods

We performed a retrospective single-center cohort study of patients treated with IHD for at least 7 days and four dialysis sessions for AKI between 2006 and 2011 in an intensive care unit (ICU) of a French university hospital. Blood and urinary markers were recorded on the day of the last IHD in the ICU for unweaned patients and 2 days after the last IHD for weaned patients. Factors associated with IHD weaning were identified by multiple logistic regression. The areas under the receiver operating characteristic curve (AUROC) and the characteristics of the best diagnostic thresholds were compared.

Results

Sixty-seven patients were analyzed, including thirty-seven IHD-weaned patients. Urine output [odds ratio (OR) 1.59, 95 % confidence interval (CI) 1.20–2.10 (per ml/kg/24 h increase); P = 0.01] and urinary urea concentration [OR 1.29, 95 % CI 1.01–1.64 (per 10 mmol/L increase); P = 0.04] were both associated with IHD weaning. The optimal diagnostic thresholds for IHD weaning were urine output greater than 8.5 ml/kg/24 h, urinary urea concentration greater than 148 mmol/L, and daily urea excretion greater than 1.35 mmol/kg/24 h, with accuracy of 82.1 %, 76.1 %, and 92.5 % (P = 0.03), respectively. The AUROC of daily urinary urea excretion (0.96) was greater than the AUROC of urine output (0.86) or the AUROC of urinary urea concentration (0.83) (P < 0.001).

Conclusions

A daily urinary urea excretion greater than 1.35 mmol/kg/24 h was found to be the best marker for weaning ICU patients with AKI from IHD.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1225-5) contains supplementary material, which is available to authorized users.

Chronic renal failure complications and management in kidney transplanted and nontransplanted patients

BACKGROUND

Our purpose was to compare the management of chronic kidney disease (CKD) according to Kidney Disease Quality Initiative (K/DOQI) recommendations in kidney transplanted patients (T) and nontransplanted ones (NT).

METHODS

Data concerning CKD complications were collected retrospectively. Patients seen in consultations in our department from May 2009 to June 2010 were selected if they had at least 6 months of follow-up, CKD stage 4 or 5, and no exclusion criteria namely hospitalization, active cancer, or infection in the 3 months before data collection.

RESULTS

Fifty-eight T were compared with 85 NT matched by CKD stage (4-5). Anemia within K/DOQI target was better controlled among NT (51.2% versus 41.3%); however, ferritin levels within K/DOQI target were higher (80% T versus 51.7% NT). Average arterial blood pressure was similar in both groups but 51.7% of T were in K/DOQI target versus 41% of NT. Dyslipidemia within cholesterol K/DOQI target was better controlled in 60% (NT) versus 35% NT with 63.5% versus 38% NT within low-density lipoprotein K/DOQI targets. Phosphorus level was better controlled among T; parathyroid was better controlled in among 65% NT versus 50% T within the target level.

CONCLUSION

Most complications of CKD were better managed among NT.

Safe use of citric acid-based dialysate and heparin removal in postdilution online hemodiafiltration

BACKGROUND

Anticoagulation of the blood circuit with heparin is essential for hemodialysis, but exposes patients to several risks (bleeding, thrombocytopenia, etc.). The use of citric acid-based dialysate (CitA-D) allows the reduction of heparin in conventional hemodialysis. We evaluated the feasibility of using CitA-D in postdilution online hemodiafiltration (OL-HDF) and of removing heparin.

METHODS

We prospectively compared chlorhydric acid-based dialysate with CitA-D in 10 patients treated by OL-HDF. First, we reduced heparin by half the dose and then we totally removed anticoagulation.

RESULTS

For all 120 sessions using heparin-free CitA-D, only one clotting episode related to an arteriovenous fistula stenosis was observed. No adverse clinical effect was observed. (Kt/V)sp, predialytic serum bicarbonate, calcium, phosphate, parathroid hormone, and β2-microglobulin remained the same in all cases.

CONCLUSION

Our data suggest that the use of CitA-D in OL-HDF is safe and allows heparin removal in most patients.