The latest medical research on Nephrology

The research magnet gathers the latest research from around the web, based on your specialty area. Below you will find a sample of some of the most recent articles from reputable medical journals about nephrology gathered by our medical AI research bot.

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Exome Chip Analyses and Genetic Risk for IgA Nephropathy among Han Chinese.

Clinical Journal of the American

IgA nephropathy is the most common form of primary GN worldwide. The evidence of geographic and ethnic differences, as well as familial aggregation of the disease, supports a strong genetic contribution to IgA nephropathy. Evidence for genetic factors in IgA nephropathy comes also from genome-wide association patient-control studies. However, few studies have systematically evaluated the contribution of coding variation in IgA nephropathy.

We performed a two-stage exome chip-based association study in 13,242 samples, including 3363 patients with IgA nephropathy and 9879 healthy controls of Han Chinese ancestry. Common variant functional annotation, gene-based low-frequency variants analysis, differential mRNA expression, and gene network integration were also explored.

We identified three non-HLA gene regions (FBXL21, CCR6, and STAT3) and one HLA gene region (GABBR1) with suggestive significance (P meta <5×10-5) in single-variant associations. These novel non-HLA variants were annotated as expression-associated single-nucleotide polymorphisms and were located in enhancer regions enriched in histone marks H3K4me1 in primary B cells. Gene-based low-frequency variants analysis suggests CFB as another potential susceptibility gene. Further combined expression and network integration suggested that the five novel susceptibility genes, TGFBI, CCR6, STAT3, GABBR1, and CFB, were involved in IgA nephropathy.

Five novel gene regions with suggestive significance for IgA nephropathy were identified and shed new light for further mechanism investigation.

Variability in Culture-Negative Peritonitis Rates in Pediatric Peritoneal Dialysis Programs in the United States.

Clinical Journal of the American

International guidelines suggest a target culture-negative peritonitis rate of <15% among patients receiving long-term peritoneal dialysis. Through a pediatric multicenter dialysis collaborative, we identified variable rates of culture-negative peritonitis among participating centers. We sought to evaluate whether specific practices are associated with the variability in culture-negative rates between low- and high-culture-negative rate centers.

Thirty-two pediatric dialysis centers within the Standardizing Care to Improve Outcomes in Pediatric End Stage Renal Disease (SCOPE) collaborative contributed prospective peritonitis data between October 1, 2011 and March 30, 2017. Clinical practice and patient characteristics were compared between centers with a ≤20% rate of culture-negative peritonitis (low-rate centers) and centers with a rate >20% (high-rate centers). In addition, centers completed a survey focused on center-specific peritoneal dialysis effluent culture techniques.

During the 5.5 years of observation, 1113 patients had 1301 catheters placed, totaling 19,025 patient months. There were 620 episodes of peritonitis in 378 patients with 411 catheters; cultures were negative in 165 (27%) peritonitis episodes from 125 (33%) patients and 128 (31%) catheters. Low-rate centers more frequently placed catheters with a downward-facing exit site and two cuffs (P<0.001), whereas high-rate centers had more patients perform dialysis themselves without the assistance of an adult care provider (P<0.001). The survey demonstrated that peritoneal dialysis effluent culture techniques were highly variable across centers. No consistent practice or technique helped to differentiate low- and high-rate centers.

Culture-negative peritonitis is a frequent complication of maintenance peritoneal dialysis in children. Despite published recommendations for dialysis effluent collection and culture methods, great variability in culture techniques and procedures exists among individual dialysis programs and respective laboratory processes.

Nicotine, Smoking, Podocytes and Diabetic Nephropathy.

American Journal of

Diabetic nephropathy (DN) is the leading cause of end-stage kidney disease. Besides glycemic and blood pressure control, environmental factors such...

The solute carrier SLC16A12 is critical for creatine and guanidinoacetate handling in the kidney.

American Journal of

A heterozygous mutation (c.643C.A; p.Q215X) in the creatine transporter SLC16A12 was proposed to cause a syndrome with juvenile cataracts, microcor...

Trends in Discard of Kidneys from Hepatitis C Viremic Donors in the United States.

Clinical Journal of the American

Kidneys from hepatitis C virus (HCV) viremic donors have become more commonly accepted for transplant, especially after effective direct-acting antiviral therapy became available in 2014. We examined the contemporary trend of kidney discard from donors with HCV seropositivity and viremia.

Data from the Organ Procurement and Transplantation Network were used to identify deceased donor kidneys recovered for transplant. The exposure was donor HCV antibody status in the first analyses, and donor HCV antibody and viremia status in the second analyses. Multilevel, multivariable logistic regression was used to assess the association of these HCV exposure measures with kidney discard, adjusted for donor characteristics. Multilevel analyses were conducted to account for similar kidney discard pattern within clusters of organ procurement organizations and regions.

Among 225,479 kidneys recovered from 2005 to 2019, 5% were from HCV seropositive donors. Compared with HCV seronegative kidneys, the odds of HCV seropositive kidney discard gradually declined, from a multivariable-adjusted odds ratio (aOR) of 7.06 (95% confidence interval [95% CI], 5.65 to 8.81) in 2014, to 1.20 (95% CI, 1.02 to 1.42) in 2019. Among 82,090 kidneys with nucleic acid amplification test results in 2015-2019, 4% were from HCV viremic donors and 2% were from aviremic seropositive donors. Compared with HCV aviremic seronegative kidneys, the odds of HCV viremic kidney discard decreased from an aOR of 4.89 (95% CI, 4.03 to 5.92) in 2018, to 1.48 (95% CI, 1.22 to 1.81) in 2019. By 2018 and 2019, aviremic seropositive status was not associated with higher odds of discard (2018: aOR, 1.13; 95% CI, 0.88 to 1.45; and 2019: aOR, 0.97; 95% CI, 0.76 to 1.23).

Despite the decrease in kidney discard in recent years, kidneys from viremic (compared with aviremic seronegative) donors still had 48% higher odds of discard in 2019. The potential of these discarded organs to provide successful transplantation should be explored.

Activation of TGR5 restores AQP2 expression via HIF pathway in renal ischemia/reperfusion injury.

American Journal of

Renal ischemia/reperfusion (I/R) injury is associated with markedly reduced the protein expression of aquaporins (AQPs). The membrane G protein-cou...

Proximal Tubule LPA1 and LPA2 Receptors use Divergent Signaling Pathways to Additively Increase Profibrotic Cytokine Secretion.

American Journal of

Lysophosphatidic acid (LPA) increases PDGFB and CTGF production and secretion by proximal tubule (PT) cells through LPA2-receptor-Gαq-αvβ6-integrin...

Activation of RAS contributes to peritoneal fibrosis via dysregulation of low-density lipoprotein receptor.

American Journal of

Peritoneal dialysis (PD)-related peritoneal fibrosis (PF) is characterized by progressive extracellular matrix (ECM) accumulation in peritoneal mes...

NAT8 Variants, N-Acetylated Amino Acids, and Progression of CKD.

Clinical Journal of the American

Genetic variants in NAT8, a liver- and kidney-specific acetyltransferase encoding gene, have been associated with eGFR and CKD in European populations. Higher circulating levels of two NAT8-associated metabolites, N-δ-acetylornithine and N-acetyl-1-methylhistidine, have been linked to lower eGFR and higher risk of incident CKD in the Black population. We aimed to expand upon prior studies to investigate associations between rs13538, a missense variant in NAT8, N-acetylated amino acids, and kidney failure in multiple, well-characterized cohorts.

We conducted analyses among participants with genetic and/or serum metabolomic data in the African American Study of Kidney Disease and Hypertension (AASK; n=962), the Atherosclerosis Risk in Communities (ARIC) study (n=1050), and BioMe, an electronic health record-linked biorepository (n=680). Separately, we evaluated associations between rs13538, urinary N-acetylated amino acids, and kidney failure in participants in the German CKD (GCKD) study (n=1624).

Of 31 N-acetylated amino acids evaluated, the circulating and urinary levels of 14 were associated with rs13538 (P<0.05/31). Higher circulating levels of five of these N-acetylated amino acids, namely, N-δ-acetylornithine, N-acetyl-1-methylhistidine, N-acetyl-3-methylhistidine, N-acetylhistidine, and N2,N5-diacetylornithine, were associated with kidney failure, after adjustment for confounders and combining results in meta-analysis (combined hazard ratios per two-fold higher amino acid levels: 1.48, 1.44, 1.21, 1.65, and 1.41, respectively; 95% confidence intervals: 1.21 to 1.81, 1.22 to 1.70, 1.08 to 1.37, 1.29 to 2.10, and 1.17 to 1.71, respectively; all P values <0.05/14). None of the urinary levels of these N-acetylated amino acids were associated with kidney failure in the GCKD study.

We demonstrate significant associations between an NAT8 gene variant and 14 N-acetylated amino acids, five of which had circulation levels that were associated with kidney failure.

Effect of Phosphate-Specific Diet Therapy on Phosphate Levels in Adults Undergoing Maintenance Hemodialysis: A Systematic Review and Meta-Analysis.

Clinical Journal of the American

Hyperphosphatemia is a persistent problem in individuals undergoing maintenance hemodialysis, which may contribute to vascular and bone complications. In some dialysis centers, dietitians work with patients to help them manage serum phosphate. Given the regularity of hyperphosphatemia in this population and constraints on kidney dietitian time, the authors aimed to evaluate the evidence for this practice.

There was a systematic review and meta-analysis of clinical trials. MEDLINE, Embase, CINAHL, Web of Science, Cochrane Central Register of Controlled Trials, and other databases were searched for controlled trials published from January 2000 until November 2019 in the English language. Included studies were required to examine the effect of phosphate-specific diet therapy provided by a dietitian on serum phosphate in individuals on hemodialysis. Risk of bias and certainty of evidence were assessed using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) method.

Of the 8054 titles/abstracts identified, 168 articles were reviewed, and 12 clinical trials (11 randomized, one nonrandomized) were included. Diet therapy reduced serum phosphate compared with controls in all studies, reaching statistical significance in eight studies, although overall certainty of evidence was low, primarily due to randomization issues and deviations from protocol. Monthly diet therapy (20-30 minutes) significantly lowered serum phosphate in patients with persistent hyperphosphatemia for 4-6 months, without compromising nutrition status (mean difference, -0.87 mg/dl; 95% confidence interval, -1.40 to -0.33 mg/dl), but appeared unlikely to maintain these effects if discontinued. Unfortunately, trials were too varied in design, setting, and approach to appropriately pool in meta-analysis, and were too limited in number to evaluate the timing, dose, and strategy of phosphate-specific diet therapy.

There is low-quality evidence that monthly diet therapy by a dietitian appears to be a safe and efficacious treatment for persistent hyperphosphatemia in patients on HD.

Network Meta-Analysis of Novel Glucose-Lowering Drugs on Risk of Acute Kidney Injury.

Clinical Journal of the American

Little is known about the comparative effects of dipeptidyl peptidase-4 (DPP-4) inhibitors, glucagon-like peptide-1 receptor agonists (GLP-1RAs), or sodium glucose cotransporter-2 (SGLT2) inhibitors on risk of AKI. This study aimed to compare the effects of these three novel classes of glucose-lowering drugs on AKI risk in patients with or without type 2 diabetes, by network meta-analysis of event-driven cardiovascular or kidney outcome trials.

We systematically searched electronic databases up to September 2020, and included 20 event-driven cardiovascular or kidney outcome trials (18 trials included patients with type 2 diabetes only, and two trials included patients with or without type 2 diabetes). A network meta-analysis using a frequentist approach was performed to compare the effects of DPP-4 inhibitors, GLP-1RAs, or SGLT2 inhibitors on risk of AKI, and estimate the probability for each intervention as the safest one. The primary analysis included 18 trials with type 2 diabetes only, and a secondary analysis included 20 trials.

In the 18 trials with a total of 2051 AKI events (range: 1-300) among 156,690 patients with type 2 diabetes only, our network meta-analysis showed that SGLT2 inhibitors were associated with a lower risk of AKI compared with placebo (odds ratio, 0.76; 95% confidence interval, 0.66 to 0.88), whereas both DPP-4 inhibitors and GLP-1RAs had neutral effects on risk of AKI. Moreover, SGLT2 inhibitors were significantly associated with a lower risk in AKI than both GLP-1RAs (odds ratio, 0.79; 95% confidence interval, 0.65 to 0.97) and DPP-4 inhibitors (odds ratio, 0.68; 95% confidence interval, 0.54 to 0.86). SGLT2 inhibitors have the highest probability of being the safest intervention (84%). The results were similar in the secondary analysis.

Current evidence indicates that SGLT2 inhibitors have a lower risk of AKI than both DPP-4 inhibitors and GLP-1RAs.

Multicenter Study of Long-Term Safety of Tolvaptan in Later-Stage Autosomal Dominant Polycystic Kidney Disease.

Clinical Journal of the American

Tolvaptan slows kidney function decline in patients with autosomal dominant polycystic kidney disease (ADPKD) at risk of rapid progression. In the 3-year Tolvaptan Efficacy and Safety in Management of ADPKD and Its Outcomes (TEMPO) 3:4, 2-year extension to TEMPO 3:4 (TEMPO 4:4), and 1-year Replicating Evidence of Preserved Renal Function: An Investigation of Tolvaptan Safety and Efficacy in ADPKD (REPRISE) trials, aquaretic adverse events were common. Serum alanine aminotransferase (ALT) or aspartate aminotransferase (AST) elevations occurred in all three studies. Three patients met Hy Law criteria (ALT or AST more than three times and total bilirubin more than two times the upper limit of normal) for severe drug-induced liver injury (two in TEMPO 3:4 and one in TEMPO 4:4). In REPRISE, liver enzyme monitoring frequency was increased to monthly, with no Hy Law cases. A long-term, phase 3 safety study has further characterized tolvaptan safety.

Subjects who completed TEMPO 4:4, REPRISE, or other tolvaptan trials could enroll in this prospective, multinational, open-label safety study. Assessments included monthly liver enzyme testing during the first 18 months of tolvaptan exposure and every 3 months thereafter.

Among 1803 subjects, median tolvaptan exposure during the extension was 651 days (interquartile range, 538-924), and cumulative exposure (extension and previous trials) was ≤11 years. Subjects entering from REPRISE placebo experienced more aquaretic adverse events compared with subjects from TEMPO 4:4 or REPRISE tolvaptan (i.e., patients with prior long-term tolvaptan exposure). Liver enzyme elevations also occurred more frequently in subjects from REPRISE placebo. Percentages experiencing ALT ≥3/≥5/ ≥10/≥20 times the upper limit of normal were 3.2%/2.1%/0.9%/0.7%, respectively, in subjects from REPRISE placebo and 0.6%-1.1%/0.0%-0.1%/0%/0%, respectively, in those from REPRISE tolvaptan and TEMPO 4:4. Percentages experiencing AST ≥3/ ≥5/≥10/≥20 times the upper limit of normal were 6.9%/3.8%/2.3%/0.8%, respectively, in subjects from REPRISE placebo and 0.9%-2.0%/0.0%-1.0%/0%/0%, respectively, in those from REPRISE tolvaptan and TEMPO 4:4. No Hy Law cases occurred.

No new safety signals emerged during this long-term extension. Monthly liver function testing for the first 18 months of treatment appeared to enable effective detection and management of transaminase elevations.

Open Label Extension of TEMPO 3:4, NCT02251275.