Urinary Plasminogen as a Marker of Disease Progression in Human Glomerular Disease.

RATIONALE & OBJECTIVE: Glomerular disorders have a highly variable clinical course, and biomarkers that reflect the molecular mechanisms underlying their progression are needed. Based on our previous work identifying plasminogen as a direct cause of podocyte injury, we designed this study to test the association between urine plasmin(ogen) (ie, plasmin and its precursor plasminogen) and end-stage kidney disease (ESKD). STUDY DESIGN: Multicenter cohort study. SETTING & PARTICIPANTS: 1,010 patients enrolled in the CureGN Cohort with biopsy-proven glomerular disease (focal segmental glomerulosclerosis, membranous nephropathy, and immunoglobulin A nephropathy). PREDICTORS: The main predictor was urine plasmin(ogen) at baseline. Levels were measured by an electrochemiluminescent immunoassay developed de novo. Traditional clinical and analytical characteristics were used for adjustment. The ratio of urine plasmin(ogen)/expected plasmin(ogen) was evaluated as a predictor in a separate model. OUTCOME: Progression to ESKD. ANALYTICAL APPROACH: Cox regression was used to examine the association between urinary plasmin(ogen) and time to ESKD. Urinary markers were log2 transformed to approximate normal distribution and normalized to urinary creatinine (Log2uPlasminogen/cr, Log2 urinary protein/cr [UPCR]). Expected plasmin(ogen) was calculated by multiple linear regression. RESULTS: Adjusted Log2uPlasminogen/cr was significantly associated with ESKD (HR per doubling Log2 uPlasminogen/cr 1.31 [95% CI, 1.22-1.40], P<0.001). Comparison of the predictive performance of the models including Log2 uPlasminogen/cr, Log2 UPCR, or both markers showed the plasmin(ogen) model superiority. The ratio of measured/expected urine plasmin(ogen) was independently associated with ESKD: HR, 0.41 (95% CI, 0.22-0.77) if ratio<0.8 and HR 2.42 (95% CI, 1.54-3.78) if ratio>1.1 (compared with ratio between 0.8 and 1.1). LIMITATIONS: Single plasmin(ogen) determination does not allow for the study of changes over time. The use of a cohort of mostly white patients and the restriction to patients with 3 glomerular disorders limits the external validity of our analysis. CONCLUSIONS: Urinary plasmin(ogen) and the ratio of measured/expected plasmin(ogen) are independently associated with ESKD in a cohort of patients with glomerular disease. Taken together with our previous experimental findings, urinary plasmin(ogen) could be a useful biomarker in prognostic decision making and a target for the development of novel therapies in patients with proteinuria and glomerular disease. PLAIN-LANGUAGE SUMMARY: Glomerular diseases are an important cause of morbidity and mortality in patients of all ages. Knowing the individual risk of progression to dialysis or transplantation would help to plan the follow-up and treatment of these patients. Our work studies the usefulness of urinary plasminogen as a marker of progression in this context, since previous studies indicate that plasminogen may be involved in the mechanisms responsible for the progression of these disorders. Our work in a sample of 1,010 patients with glomerular disease demonstrates that urinary plasminogen (as well as the ratio of measured to expected plasminogen) is associated with the risk of progression to end-stage kidney disease. Urine plasminogen exhibited good performance and, if further validated, could enable risk stratification for timely interventions in patients with proteinuria and glomerular disease.

Retinal thickness as potential biomarker in posterior cortical atrophy and typical Alzheimer's disease.

BACKGROUND: Retinal thickness can be measured non-invasively with optical coherence tomography (OCT) and may offer compelling potential as a biomarker for Alzheimer's disease (AD). Retinal thinning is hypothesized to be a result of retrograde atrophy and/or parallel neurodegenerative processes. Changes in the visual pathway are of particular interest in posterior cortical atrophy (PCA), the most common atypical AD phenotype predominantly affecting the parietal-occipital cortices. We therefore evaluated retinal thickness as non-invasive biomarker of neurodegeneration in well-characterized participants with posterior cortical atrophy (PCA) and typical Alzheimer's disease (tAD). METHODS: Retinal thickness measures were acquired from 48 patient participants (N = 25 PCA; N = 23 tAD) fulfilling consensus diagnostic criteria and 70 age-matched controls. Participants were recruited between 2014 and 2016. All participants underwent optical coherence tomography (OCT) imaging, including measurement of peripapillary retinal nerve fiber layer (pRNFL) thickness and total macular thickness (mRT). Participants did not show evidence of any significant ophthalmological conditions. Subgroup analyses were performed in participants with available MRI and CSF measures, providing evidence of neurodegeneration and underlying AD pathology respectively. RESULTS: There was no evidence of overall between-group differences in pRNFL thickness (mean PCA 98.7 ± 12.2; tAD 99.9 ± 8.7; controls 99.6 ± 10.0 µm, one-way analysis of variance (ANOVA) p = 0.92) or total mRT (mean PCA 266.9 ± 16.3; tAD 267.8 ± 13.6; controls 269.3 ± 13.6 µm, one-way ANOVA p = 0.75). Similarly, subgroup analysis with MRI biomarkers (PCA = 18, tAD = 17, controls = 31) showing neurodegeneration, and CSF biomarkers (PCA = 18, tAD = 14, controls = 13) supporting underlying AD pathology did not provide evidence of overall between-group differences in pRNFL or mRT measures (all p > 0.3). CONCLUSIONS: Retinal thickness did not discriminate tAD and PCA from controls or from one another despite unequivocal differences on standard clinical, neuro-imaging and CSF measures. Findings from this well-characterized sample, including cases with PCA, do not support the hypothesis that retinal neurodegeneration, measured using conventional OCT, is a useful biomarker for AD or PCA.

Improving clinical outcomes among hemodialysis patients: a proposal for a "volume first" approach from the chief medical officers of US dialysis providers.

Addressing fluid intake and volume control requires alignment and coordination of patients, providers, dialysis facilities, and payers, potentially necessitating a "Volume First" approach. This article reports the consensus opinions achieved at the March 2013 symposium of the Chief Medical Officers of 14 of the largest dialysis providers in the United States. These opinions are based on broad experience among participants, but often reinforced by only observational and frequently retrospective studies, highlighting the lack of high-quality clinical trials in nephrology. Given the high morbidity and mortality rates among dialysis patients and the absence of sufficient trial data to guide most aspects of hemodialysis therapy, participants believed that immediate attempts to improve care based on quality improvement initiatives, physiologic principles, and clinical experiences are warranted until such time as rigorous clinical trial data become available. The following overarching consensus opinions emerged. (1) Extracellular fluid status should be a component of sufficient dialysis, such that approaching normalization of extracellular fluid volume should be a primary goal of dialysis care. (2) Fluid removal should be gradual and dialysis treatment duration should not routinely be less than 4 hours without justification based on individual patient factors. (3) Intradialytic sodium loading should be avoided by incorporating dialysate sodium concentrations set routinely in the range of 134-138 mEq/L, avoidance of routine use of sodium modeling, and avoidance of hypertonic saline solution. (4) Dietary counseling should emphasize sodium avoidance.

Development and validation of a whole genome amplification long-range PCR sequencing method for ADPKD genotyping of low-level DNA samples.

Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in two large genes, PKD1 and PKD2, but genetic testing is complicated by the large transcript sizes and the duplication of PKD1 exons 1-33 as six pseudogenes on chromosome 16. Long-range PCR (LR-PCR) represents the gold standard approach for PKD1 genetic analysis. However, a major issue with this approach is that it requires large quantities of genomic DNA (gDNA) material limiting its application primarily to DNA extracted from blood. In this study, we have developed a whole genome amplification (WGA)-based genotyping assay for PKD1 and PKD2, and examined whether this approach can be applied to biosamples with low DNA yield, including blood, buccal cells and urine. DNA samples were amplified by multiple displacement amplification (MDA) and a high-fidelity DNA polymerase followed by LR-PCR and exon-specific amplifications of PKD1 and PKD2 respectively, and Sanger sequencing. This method has generated large amounts of DNA with high average product length (>10 kb), which were uniformly amplified across all sequences assessed. When compared to the gDNA direct sequencing method for six ADPKD samples, a total of 89 variants were detected including all 86 variations previously reported, in addition to three new variations, including one pathogenic mutation not previously detected by the standard gDNA-based analysis. We have further applied WGA to ADPKD mutation analysis of low DNA-yield specimens, successfully detecting all 63 gene variations. Compared to the gDNA method the WGA-based assay had a sensitivity and specificity of 100%. In conclusion, WGA-based LR-PCR represents a major technical improvement for PKD genotyping from trace amounts of DNA.

Molecular diagnosis of autosomal dominant polycystic kidney disease using next-generation sequencing.

Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in PKD1 and PKD2. However, genetic analysis is complicated by six PKD1 pseudogenes, large gene sizes, and allelic heterogeneity. We developed a new clinical assay for PKD gene analysis using paired-end next-generation sequencing (NGS) by multiplexing individually bar-coded long-range PCR libraries and analyzing them in one Illumina MiSeq flow cell. The data analysis pipeline has been optimized and automated with Unix shell scripts to accommodate variant calls. This approach was validated using a cohort of 25 patients with ADPKD previously analyzed by Sanger sequencing. A total of 250 genetic variants were identified by NGS, spanning the entire exonic and adjacent intronic regions of PKD1 and PKD2, including all 16 pathogenic mutations. In addition, we identified three novel mutations in a mutation-negative cohort of 24 patients with ADPKD previously analyzed by Sanger sequencing. This NGS method achieved sensitivity of 99.2% (95% CI, 96.8%-99.9%) and specificity of 99.9% (95% CI, 99.7%-100.0%), with cost and turnaround time reduced by as much as 70%. Prospective NGS analysis of 25 patients with ADPKD demonstrated a detection rate comparable with Sanger standards. In conclusion, the NGS method was superior to Sanger sequencing for detecting PKD gene mutations, achieving high sensitivity and improved gene coverage. These characteristics suggest that NGS would be an appropriate new standard for clinical genetic testing of ADPKD.

A quality initiative. Reducing rates of hospitalizations by objectively monitoring volume removal.

Morbidity, hospitalizations, and costs for the treatment of individuals with end-stage renal disease are simply not improving at a rate that is acceptable to many physicians and dialysis providers in the United States. Various conferences and papers have suggested what processes need to become part of the dialysis prescription to accelerate change. Controlling cardiovascular disease is a part of that change, and controlling extra-cellular volume (ECV) is necessary to accomplish this. Three dialysis providers joined in a quality initiative to objectively assess the ultrafiltration process and measure "normalized" ECV, with the outcome objective to decrease ECV-related hospitalizations. The results show a decrease in ECV-related hospitalizations by 50%. The model of dialysis prescription needs to now change to Kt/V + objective ECV control.

The economic burden of geriatric ESRD.

The elderly represent the fastest growing segment of incident patients entering end-stage renal disease (ESRD). Increasingly, social scientists and caregivers are faced with changing models of care, which will challenge traditional patterns of patient acceptance into costly medical therapies. This paper analyzes the outcomes and cost of taking care of patients over the age of 65, and compares these costs and outcomes with other age groups. The results are somewhat unexpected, in that the incremental costs are not appreciably higher, although the outcomes are considerably worse compared with that in younger age groups. Proposals are made for addressing these issues.

A crucial lifeline: reducing mortality in the first 120 days.

Data from the United States Renal Data System shows that mortality and hospitalization rates for prevalent ESRD patients is high and has only gradually improved year after year. Furthermore, the same rates are even higher for patients in the first year of care, especially the first 120 days. Renal Ventures Coaching for Actions, Results, and Empowerment (RVCARE) was developed to reduce the high mortality and hospitalization risk, improve cardiovascular disease, decrease the use of catheters, offer optimal modalities of therapy, and change other outcomes in incident patients undergoing in-center hemodialysis. The results demonstrate that it is indeed possible to positively affect these outcomes, even in a small dialysis organization (SDO).

A novel long-range PCR sequencing method for genetic analysis of the entire PKD1 gene.

Genetic testing of PKD1 and PKD2 is useful for the diagnosis and prognosis of autosomal dominant polycystic kidney disease; however, analysis is complicated by the large transcript size, the complexity of the gene region, and the high level of gene variations. We developed a novel mutation screening assay for PKD1 by directly sequencing long-range (LR) PCR products. By using this method, the entire PKD1 coding region was amplified by nine reactions, generating product sizes from 2 to 6 kb, circumventing the need for specific PCR amplification of individual exons. This method was compared with direct sequencing used by a reference laboratory and the SURVEYOR-WAVE Nucleic Acid High Sensitivity Fragment Analysis System (Transgenomic) screening method for five patients with autosomal dominant polycystic kidney disease. A total of 53 heterozygous genetic changes were identified by LR PCR sequencing, including 41 (of 42) variations detected by SURVEYOR nuclease and all 32 variations reported by the reference laboratory, detecting an additional 12 intronic changes not identified by the other two methods. Compared with the reference laboratory, LR PCR sequencing had a sensitivity of 100%, a specificity of 98.5%, and an accuracy of 98.8%; compared with the SURVEYOR-WAVE method, it had a sensitivity of 97.1%, a specificity of 100%, and an accuracy of 99.4%. In conclusion, LR PCR sequencing was superior to the direct sequencing and screening methods for detecting genetic variations, achieving high sensitivity and improved intronic coverage with a faster turnaround time and lower costs, and providing a reliable tool for complex genetic analyses.

Dialysis practices that distinguish facilities with below- versus above-expected mortality.

BACKGROUND AND OBJECTIVES: Mortality rates vary widely among dialysis facilities even after adjustment with standardized mortality ratios (SMRs). This variation may occur because top-performing facilities use practices not shared by others, because the SMR fails to capture key patient characteristics, or both. Practices were identified that distinguish top- from bottom-performing facilities by SMR. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: A cross-sectional survey was performed of staff across three organizations. Staff members rated the perceived quality of their units' patient-, provider-, and facility-level practices using a six-point Likert scale. Facilities were divided into those with above- versus below-expected mortality on the basis of SMRs from U.S. Renal Data Service facility reports. Mean Likert scores were computed for each practice using t tests. Practices that were statistically significant (P ≤ 0.05) and achieved at least a medium effect size of ≥0.4 were reported. Significant predictors were entered into a linear regression model. RESULTS: Dialysis facilities with below-expected mortality reported that patients in their unit were more activated and engaged, physician communication and interpersonal relationships were stronger, dieticians were more resourceful and knowledgeable, and overall coordination and staff management were superior versus facilities with above-expected mortality. Staff ratings of these practices explained 31% of the variance in SMRs. CONCLUSIONS: Patient-, provider-, and facility-level practices partly explain SMR variation among facilities. Improving SMRs may require processes that reflect a coordinated, multidisciplinary environment (i.e., no one group, practice, or characteristic will drive facility-level SMRs). Understanding and improving SMRs will require a holistic view of the facility.

Definition of chronic kidney disease after uninephrectomy in living donors: what are the implications?

BACKGROUND: Living kidney transplant donors generally have a favorable renal functional outcome postuninephrectomy, but concern remains that a reduced glomerular filtration rate (GFR) postuninephrectomy might have harmful effects. This study examines the short-term (3 months) effect of donor nephrectomy on GFR and the occurrence of stage 3 chronic kidney disease (CKD) postuninephrectomy. METHODS: The prevalence of stage 3 CKD (Kidney Disease Quality Outcome Initiative [GFR<60 mL/min/1.73 m]) was examined in 196 living donors by comparing preuninephrectomy and 3-month postuninephrectomy values of GFR using I-iothalamate GFR (iGFR), modification of diet in renal disease estimated GFR (eGFR), Cockcroft-Gault estimated creatinine clearance, and endogenous 24-hr creatinine clearance. The accuracy of GFR estimations for predicting iGFR was also studied. RESULTS: The mean GFR before and after donation were iGFR, 105+/-18 and 68+/-13 mL/min/1.73 m; eGFR, 98+/-19 and 63+/-12 mL/min/1.73 m; Cockcroft-Gault estimated creatinine clearance, 125+/-33 and 85+/-22 mL/min/1.73 m, and endogenous 24-hr creatinine clearance, 133+/-38 and 86+/-24 mL/min/1.73 m, respectively. Stage 3 CKD was found postuninephrectomy in 53 donors (27%) by iGFR and in 73 donors (38%) by eGFR. The prevalence of stage 3 CKD was greater with older age. GFR estimation equations did not accurately predict iGFR, particularly postuninephrectomy. CONCLUSIONS: Stage 3 CKD is commonly observed after living kidney donation, particularly in older donors. The long-term impact of stage 3 CKD postuninephrectomy is poorly understood and may not have the same implications as stage 3 CKD in other conditions. eGFR is a poor predictor of true GFR in kidney donors.

Dialysis practices that distinguish top- versus bottom-performing facilities by hemoglobin outcomes.

BACKGROUND: Because there is wide variation in outcomes across dialysis facilities, it is possible that top-performing units use practices not shared by others. The Identifying Best Practices in Dialysis (IBPiD) Study seeks to identify practices that distinguish top- from bottom-performing facilities by key outcomes, including achievement of recommended hemoglobin targets. STUDY DESIGN: Observational study with cross-sectional study ascertainment of predictors and outcomes. PREDICTORS: Facility dialysis practices ascertained using practice surveys of dialysis staff who indicated their level of agreement that each practice occurs in their facility (1-6 on a Likert scale). SETTING & PARTICIPANTS: 423 personnel in 90 dialysis facilities from 1 for-profit and 2 not-for-profit dialysis organizations. OUTCOMES: Percentage of patients per month per facility with hemoglobin levels of 11-12 g/dL. We divided facilities by median into top- versus bottom-performing groups and compared mean scores for each practice using t tests. We report practices that were statistically significant and achieved at least a medium effect size (ES) >or=0.4. RESULTS: 17 of 155 tested predictors were significant. Achievement of hemoglobin level targets was related most strongly to the use of chairside computers (ES, 0.8 [95% CI, 0.4-1.4]), extent/quality of educational videos (ES, 0.6 [95% CI, 0.2-1.1]), frequency of calling per diem staff if short staffed (ES, 0.6 [95% CI, 0.21-1.1]), policy that nurses pass written competency examinations before hire (ES, 0.6 [95% CI, 0.2-1.0]), and technician cannulation mastery (ES, 0.6 [95% CI, 0.2-1.1]). LIMITATIONS: This is a cross-sectional study that can address only associations, not causations. Future research should measure the longitudinal predictive value of these practices. CONCLUSIONS: High-performing facilities report more effective education programs, better staff management, higher staff competency, and higher use of chairside computers, a potential marker of information technology proficiency. This suggests that hemoglobin level management is enhanced by processes reflecting a coordinated multidisciplinary environment.

Human neutrophil peptides: a novel potential mediator of inflammatory cardiovascular diseases.

The traditional view of atherosclerosis has recently been expanded from a predominantly lipid retentive disease to a coupling of inflammatory mechanisms and dyslipidemia. Studies have suggested a novel role for polymorphonuclear neutrophil (PMN)-dominant inflammation in the development of atherosclerosis. Human neutrophil peptides (HNPs), also known as alpha-defensins, are secreted and released from PMN granules upon activation and are conventionally involved in microbial killing. Current evidence suggests an important immunomodulative role for these peptides. HNP levels are markedly increased in inflammatory diseases including sepsis and acute coronary syndromes. They have been found within the intima of human atherosclerotic arteries, and their deposition in the skin correlates with the severity of coronary artery diseases. HNPs form complexes with LDL in solution and increase LDL binding to the endothelial surface. HNPs have also been shown to contribute to endothelial dysfunction, lipid metabolism disorder, and the inhibition of fibrinolysis. Given the emerging relationship between PMN-dominant inflammation and atherosclerosis, HNPs may serve as a link between them and as a biological marker and potential therapeutic target in cardiovascular diseases including coronary artery diseases and acute coronary syndromes.