Endurance-oriented training program with children and adolescents on maintenance hemodialysis to enhance dialysis efficacy-DiaSport.

OBJECTIVE: Pediatric patients spend significant time on maintenance hemodialysis (HD) and traveling. They are often not capable of participating in sports activities. To assess the effects of exercise training during HD on dialysis efficacy in children and adolescents, we set up a multi-center randomized controlled trial (RCT). METHODS: Patients on HD, age 6 to 18 years, were randomized either to 3× weekly bicycle ergometer training or to no training during HD for 12 weeks. Change in single-pool Kt/V (spKt/V) was the primary outcome parameter. RESULTS: We randomized 54 patients of whom 45 qualified (23 in the intervention and 22 in the waiting control group, 14.5 ± 3.01 years, 32 male and 13 female) for the intention-to-treat (ITT) population. Only 26 patients finished study per-protocol (PP). Training was performed for an average of 11.96 weeks (0.14-13.14) at 2.08 ± 0.76 times per week and for a weekly mean of 55.52 ± 27.26 min. Single-pool Kt/V was similar in the intervention compared to the control group (1.70 [0.33] vs. 1.79 [0.55]) at V0 and (1.70 [0.36] vs. 1.71 [0.51]) at V1; secondary endpoints also showed no difference in both ITT and PP analysis. No significant adverse events were reported. No bleeding or needle dislocation occurred in 1670 training sessions. CONCLUSIONS: Intradialytic bicycle training is safe, but does not improve dialysis efficacy and physical fitness. However, the study can be considered underpowered, particularly because of high dropout rates. Future studies need better strategies to increase motivation and compliance and other more effective/intensive exercise measures should be evaluated. TRIAL REGISTRATION: The trial was registered in ClinicalTrials.Gov ( Clinicaltrials.gov identifier: NCT01561118) on March 22, 2012.

Subclinical myocardial disease in patients with primary hyperoxaluria and preserved left ventricular ejection fraction: a two-dimensional speckle-tracking imaging study.

BACKGROUND: Primary hyperoxaluria (PH) is characterized by progressive chronic kidney disease (CKD) and systemic oxalate deposition. Myocardial dysfunction might be present early in the course of the disease. However, this hypothesis has not yet been tested in the PH population. Therefore, we aimed to determine whether strain imaging using two-dimensional speckle tracking echocardiography (2D-STE) might detect subclinical myocardial disease in otherwise asymptomatic PH patients. METHODS: Prospective study of pediatric and adolescent PH patients with preserved LV ejection fraction (LV EF) and without renal replacement therapy. Subjects underwent conventional echocardiography and 2D-STE. Global (GLS) and segmental peak systolic LV longitudinal strain (LS) measurements were obtained. Data were compared with age- and gender-matched controls, and Z-scores were calculated as appropriate. RESULTS: Fifteen PH patients (age 14.1 ± 5.9 years; 13/15 in CKD stages 1-2) were studied. Although LV EF was preserved (63 ± 6%) in patients, GLS was significantly impaired (GLS - 17.1 ± 2.2% vs - 22.4 ± 1.9%, p < 0.001). This was mainly due to decreased LS values in the apical segments (p < 0.05). Echocardiographic indices of ventricular wall thickness were significantly increased in patients compared to controls (all p < 0.03). GLS correlated significantly with Z-scores of diastolic interventricular wall thickness (r = - 0.57, p = 0.025) and moderately with serum creatinine levels (r = 0.53, p = 0.044). No correlation was found between GLS and blood pressure measurements. CONCLUSIONS: Subclinical myocardial disease is already present early in the course of disease in PH patients with preserved LV EF and some degree of renal dysfunction, but without overt systemic oxalosis. Current recommendations to screen only PH patients with advanced CKD for cardiac disease should be revised accordingly.

Rare Variants in BNC2 Are Implicated in Autosomal-Dominant Congenital Lower Urinary-Tract Obstruction.

Congenital lower urinary-tract obstruction (LUTO) is caused by anatomical blockage of the bladder outflow tract or by functional impairment of urinary voiding. About three out of 10,000 pregnancies are affected. Although several monogenic causes of functional obstruction have been defined, it is unknown whether congenital LUTO caused by anatomical blockage has a monogenic cause. Exome sequencing in a family with four affected individuals with anatomical blockage of the urethra identified a rare nonsense variant (c.2557C>T [p.Arg853∗]) in BNC2, encoding basonuclin 2, tracking with LUTO over three generations. Re-sequencing BNC2 in 697 individuals with LUTO revealed three further independent missense variants in three unrelated families. In human and mouse embryogenesis, basonuclin 2 was detected in lower urinary-tract rudiments. In zebrafish embryos, bnc2 was expressed in the pronephric duct and cloaca, analogs of the mammalian lower urinary tract. Experimental knockdown of Bnc2 in zebrafish caused pronephric-outlet obstruction and cloacal dilatation, phenocopying human congenital LUTO. Collectively, these results support the conclusion that variants in BNC2 are strongly implicated in LUTO etiology as a result of anatomical blockage.

A classic twin study of lower urinary tract obstruction: Report of 3 cases and literature review.

OBJECTIVE: The aim of the present study was to investigate genetic effects in the formation of congenital lower urinary tract obstruction (LUTO) comprising posterior urethral valves (PUV), urethral atresia, and urethras with variable degrees of stenosis. METHODS: A classic twin study was performed by assessing LUTO twin pairs from the literature. Furthermore, data regarding 3 previously unreported twin pairs with PUV from University of Bonn, Essen and Wroclaws own in-house databases were added. Both pair- and probandwise concordance rates were calculated and compared for monozygotic (MZ) and dizygotic (DZ) twin pairs. RESULTS: The pairwise concordance rates for all LUTO were 53% (95% confidence interval [CI] 32%-73%) and 17% (95% CI 3%-56%) for MZ and DZ twin pairs, respectively (P = .180). The probandwise concordance rates were 69% (95% CI 51%-83%) and 29% (CI 95% 8%-64%) for MZ and DZ twin pairs respectively (P = .084). The MZ/DZ ratios of the pair- and probandwise concordance rates were 3.1 and 2.4, respectively. CONCLUSION: The present study did not show significant differences in comparisons of concordance rates of MZ and DZ twin pairs, probably due to the small number of twin pairs reported. However, the more than 2-fold higher pair- and probandwise concordance rates for MZ versus DZ twin pairs are very suggestive of a contribution of genetic factors to the development of LUTO.

Correction to: Systematic assessment of urinary hydroxy-oxo-glutarate for diagnosis and follow up of primary hyperoxaluria type III.

The unit of the HOG-creatinine ratio presented in this article is calculated in µmol/mg creatinine instead of the demonstrated unit of µmol/µmol. This applies to the parameter in the text of the article and the labeling of Figs. 1, 2b and 3c.

Prenatal parental decision-making and postnatal outcome in renal oligohydramnios.

BACKGROUND: Previous studies on renal oligohydramnios (ROH) report highly variable outcome and identify early onset of ROH and presence of extrarenal manifestations as predictors of adverse outcome in most cases. Data on termination of pregnancy (TOP) and associated parental decision-making processes are mostly missing, but context-sensitive for the interpretation of these findings. We provide here a comprehensive analysis on the diagnosis, prenatal decision-making and postnatal clinical course in all pregnancies with ROH at our medical centre over an 8-year period. METHODS: We report retrospective chart review data on 103 consecutive pregnancies from 2008 to 2015 with a median follow-up of 554 days. RESULTS: After ROH diagnosis, 38 families opted for TOP. This decision was associated with onset of ROH (p < 0.001), underlying renal disease (p = 0.001) and presence of extrarenal manifestations (p = 0.02). Eight infants died in utero and 8 cases were lost to follow-up. Of the 49 liveborn children, 11 received palliative and 38 underwent active care. Overall survival of the latter group was 84.2% (n = 32) corresponding to 31% of all pregnancies (32 out of 103) analysed. One third of the surviving infants needed renal replacement therapy during the first 6 weeks of life. CONCLUSIONS: Over one third of pregnancies with ROH were terminated and the parental decision was based on risk factors associated with adverse outcome. Neonatal death was rare in the actively treated infants and the overall outcome promising. Our study illustrates that only careful analysis of the whole process, from prenatal diagnosis via parental decision-making to postnatal outcome, allows sensible interpretation of outcome data.

Systematic assessment of urinary hydroxy-oxo-glutarate for diagnosis and follow-up of primary hyperoxaluria type III.

BACKGROUND: There are currently three distinct autosomal recessive inherited types of primary hyperoxaluria (PH: PHI, PHII, and PHIII), all characterized by the endogenous overproduction of oxalate. The PH type is difficult to differentiate by clinical features alone. In addition to universal general characteristics to all hyperoxaluria subtypes, specific urinary metabolites can be detected: glycolate in PHI, L-glyceric acid in PHII, and hydroxy-oxo-glutarate (HOG) in PHIII. PHIII is considered to be the most benign form and is characterized by severe recurrent urolithiasis in early life, followed by clinical remission in many, but not all patients. We examined urinary HOG (UHOG) excretion as a diagnostic marker and its correlation to progression of the clinical course of PHIII. METHODS: UHOG was analyzed by combined ion chromatography/mass spectrometry (IC/MS) in urine samples from 30 PHIII and 68 PHI/II patients and 79 non-PH hyperoxaluria patients. RESULTS: Mean UHOG excretion was significantly higher in patients with PHIII than in those with PHI/II and in non-PH patients(51.6 vs. 6.61 vs. 8.36 µmol/1.73 m2/24 h, respectively; p<0.01). CONCLUSIONS: Significantly elevated UHOG excretion was exclusively seen in PHIII patients and showed a 100 % consensus with the results of hydroxy-oxo-glutarate aldolase (HOGA1) mutational analysis in newly diagnosed patients. However, UHOG excretion did not correlate with clinical course on follow-up and could not be used to discriminate between active stone formers and patients with a clinically uneventful follow-up.

Transition structures and timing of transfer from paediatric to adult-based care after kidney transplantation in Germany: a qualitative study.

OBJECTIVES: It is known that transition, as a shift of care, marks a vulnerable phase in the adolescents' lives with an increased risk for non-adherence and allograft failure. Still, the transition process of adolescents and young adults living with a kidney transplant in Germany is not well defined. The present research aims to assess transition-relevant structures for this group of young people. Special attention is paid to the timing of the process. SETTING: In an observational study, we visited 21 departments of paediatric nephrology in Germany. Participants were doctors (n=19), nurses (n=14) and psychosocial staff (n=16) who were responsible for transition in the relevant centres. Structural elements were surveyed using a short questionnaire. The experiential viewpoint was collected by interviews which were transcribedverbatim before thematic analysis was performed. RESULTS: This study highlights that professionals working within paediatric nephrology in Germany are well aware of the importance of successful transition. Key elements of transitional care are well understood and mutually agreed on. Nonetheless, implementation within daily routine seems challenging, and the absence of written, structured procedures may hamper successful transition. CONCLUSIONS: While professionals aim for an individual timing of transfer based on medical, social, emotional and structural aspects, rigid regulations on transfer age as given by the relevant health authorities add on to the challenge. TRIAL REGISTRATION NUMBER: ISRCTN Registry no 22988897; results (phase I) and pre-results (phase II).

A case report on the exceptional coincidence of two inherited renal disorders: ADPKD and Alport syndrome
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Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic cause of dialysis-requiring end-stage renal disease in adults and is characterized by the slowly progressing replacement of renal tissue by focal macrocysts. Alport syndrome (AS; hereditary nephritis) is a rare, inherited disorder of the basement membrane associated with hematuria, proteinuria, and loss of kidney function as well as sensorineural hearing loss and ocular abnormalities. Here, we report on a family in which both ADPKD and AS are present. In a male patient, both -ADPKD and AS coincided. This patient shows the very rare coexistence of two severe, inherited renal disorders and illustrates the importance of considering additional diagnoses in the setting of positive family history for a common hereditary disorder.
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Prospective study on the potential of RAAS blockade to halt renal disease in Alport syndrome patients with heterozygous mutations.

BACKGROUND: Patients with autosomal or X-linked Alport syndrome (AS) with heterozygous mutations in type IV collagen genes have a 1-20 % risk of progressing to end-stage renal disease during their lifetime. We evaluated the long-term renal outcome of patients at risk of progressive disease (chronic kidney disease stages 1-4) with/without nephroprotective therapy. METHODS: This was a prospective, non-interventional, observational study which included data from a 4-year follow-up of AS patients with heterozygous mutations whose datasets had been included in an analysis of the 2010 database of the European Alport Registry. Using Kaplan-Meier estimates and logrank tests, we prospectively analyzed the updated datasets of 52 of these patients and 13 new datasets (patients added to the Registry after 2011). The effects of therapy, extrarenal symptoms and inheritance pattern on renal outcome were analyzed. RESULTS: The mean prospective follow-up was 46 ± 10 months, and the mean time on therapy was 8.4 ± 4.4 (median 7; range 2-18) years. The time from the appearance of the first symptom to diagnosis was 8.1 ± 14.2 (range 0-52) years. At the time of starting therapy, 5.4 % of patients had an estimated glomerular filtration rate of <60 ml/min, 67.6 % had proteinuria and 27.0 % had microalbuminuria. Therapeutic strategies included angiotensin-converting enzymer inhibitors (97.1 %), angiotensin receptor antagonists (1 patient), dual therapy (11.8 %) and statins (8.8 %). Among patients included in the prospective dataset, prevented the need for dialysis. Among new patients, no patient at risk for renal failure progressed to the next disease stage after 4 years follow-up; three patients even regressed to a lower stage during therapy. CONCLUSIONS: Treatment with blockers of the renin-angiotensin-aldosterone system prevents progressive renal failure in AS patients with heterozygous mutations in the genes causing AS. Considerable numbers of aging AS patients on dialysis may have heterozygous mutations in these genes (present in 1 % of total population) as underlying disease. Hence, greater alertness towards timely diagnosis and therapy has the potential to prevent progressive renal failure in most-if not all-AS patients with heterozygous mutations in the causal genes.

Clinical and molecular characterization of patients with heterozygous mutations in wilms tumor suppressor gene 1.

BACKGROUND AND OBJECTIVES: The Wilms tumor suppressor gene 1 (WT1) plays an essential role in urogenital and kidney development. Genotype/phenotype correlations of WT1 mutations with renal function and proteinuria have been observed in world-wide cohorts with nephrotic syndrome or Wilms tumor (WT). This study analyzed mid-European patients with known constitutional heterozygous mutations in WT1, including patients without proteinuria or WT. DESIGN, SETTING, PARTICIPANTS & MEASUREMENTS: Retrospective analysis of genotype, phenotype, and treatment of 53 patients with WT1 mutation from all pediatric nephrology centers in Germany, Austria, and Switzerland performed from 2010 to 2012. RESULTS: Median age was 12.4 (interquartile range [IQR], 6-19) years. Forty-four of 53 (83%) patients had an exon mutation (36 missense, eight truncating), and nine of 53 (17%) had an intronic lysine-threonine-serine (KTS) splice site mutation. Fifty of 53 patients (94%) had proteinuria, which occurred at an earlier age in patients with missense mutations (0.6 [IQR, 0.1-1.5] years) than in those with truncating (9.7 [IQR, 5.7-11.9]; P<0.001) and splice site (4.0 [IQR, 2.6-6.6]; P=0.004) mutations. Thirteen of 50 (26%) were treated with steroids and remained irresponsive, while three of five partially responded to cyclosporine A. Seventy-three percent of all patients required RRT, those with missense mutations significantly earlier (at 1.1 [IQR, 0.01-9.3] years) than those with truncating mutations (16.5 [IQR, 16.5-16.8]; P<0.001) and splice site mutations (12.3 [IQR, 7.9-18.2]; P=0.002). Diffuse mesangial sclerosis was restricted to patients with missense mutations, while focal segmental sclerosis occurred in all groups. WT occurred only in patients with exon mutations (n=19). Fifty of 53 (94%) patients were karyotyped: Thirty-one (62%) had XY and 19 (38%) had XX chromosomes, and 96% of male karyotypes had urogenital malformations. CONCLUSIONS: Type and location of WT1 mutations have predictive value for the development of proteinuria, renal insufficiency, and WT. XY karyotype was more frequent and associated with urogenital malformations in most cases.

Diagnosis of Alport syndrome--search for proteomic biomarkers in body fluids.

BACKGROUND: The hereditary kidney disease Alport syndrome (AS) has become a treatable disease: intervention with angiotensin-converting enzyme (ACE)-inhibitors delays end stage renal failure by years. The efficiency of ACE inhibition depends on the onset of therapy-the earlier the better. Therefore, early diagnosis has become increasingly important. To date, robust diagnosis requires renal biopsy and/or expensive genetic analysis, which is mostly performed late after onset of the profound clinical symptoms of this progressive renal disease. Thus, disease biomarkers enabling low-invasive screening are urgently required. METHODS: Fourteen potential proteomic candidate markers (proteins) identified in a previous study in sera from patients exhibiting manifest AS were evaluated in the plasma, serum, and urine collected from a cohort of 132 subjects, including patients with AS and other nephropathies and healthy controls. Quantitation was performed by immunoassays. RESULTS: The serum and plasma levels of none of the 14 proteins evaluated were significantly different among the three groups and therefore could not be used to discriminate between the groups. In contrast, the levels of various biomarker combinations in the urine were significantly different between AS patients and healthy controls. Importantly, some combinations had the potential to discriminate between AS and other nephropathies. CONCLUSIONS: These findings open a window of opportunity for the sensitive and specific early diagnosis of AS. Our results increase the potential for larger scale evaluation of an increased number of patients.

Liquid chromatography-tandem mass spectrometry method for the quantification of mycophenolic acid and its phenolic glucuronide in saliva and plasma using a standardized saliva collection device.

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for simultaneous quantification of mycophenolic acid (MPA) and its phenolic glucuronide (MPAG) in saliva and plasma. Saliva was collected and processed using a standardized commercially available collection device. Sample preparation comprised of protein precipitation with acetonitrile and subsequent centrifugation, followed by evaporation and reconstitution with mobile phase. A labeled isotope of MPA was used as internal standard, and chromatographic separation was achieved on a C18 column with an isocratic flow. LC-MS/MS detection was performed using a triple-stage quadrupole mass spectrometer working in selected reaction monitoring mode with positive electrospray ionization (ESI). The analytes were quantified in a single run within 2 min. For saliva, linearity was demonstrated over the concentration range of 5.0 to 400.0 ng/ml for both MPA and MPAG, and from 0.08 to 20.00 µg/ml for MPA and 0.4 to 100.0 µg/ml for MPAG in plasma. The lower limits of quantification for MPA and MPAG were 0.07 and 0.80 ng/ml in saliva, and 0.002 and 0.009 µg/ml in plasma, respectively. Inter- and intra-day precisions expressed as relative standard deviation (RSD) and accuracies were less than 15%. The recoveries for MPA and MPAG from the collection device's swab were higher than 90%. Sample stability was confirmed for bench times up to 24 h at room temperature. The method was validated according to International Conference on Harmonization (ICH) guidelines Q2 (R1) Validation of Analytical Procedures. The applicability of the method was tested in a renal pediatric patient. Based on a limited sampling strategy, MPA saliva and plasma concentrations were found in good agreement with each other. We suggest that the described method is suitable to analyze saliva and plasma samples of small volumes for therapeutic drug monitoring (TDM) and pharmacokinetic studies in pediatric patients.

Cardiorespiratory capacity in children and adolescents on maintenance haemodialysis.

BACKGROUND: Paediatric patients on maintenance haemodialysis (HD) often report their own physical fitness to be hampered. Their physical endurance capacity is known to be significantly lower than that of healthy controls. However, physical endurance was up to now only examined on non-HD days. We were interested in the effect of HD on the cardiorespiratory capacity of children and adolescents on maintenance HD. METHODS: We therefore examined the endurance capacity by cardiopulmonary exercise testing on a cycle ergospirometer, before and after HD in 14 patients (9 male, 5 female; mean age: 15.1 ± 3.0 years; mean period on HD: 16.3 ± 11.5 months). RESULTS: The feasible time spent on the cycle ergospirometer was significantly reduced after dialysis (8.6 ± 3.2 versus 6.4 ± 2.5 min, P < 0.001), also the maximal workload was decreased (95 ± 36 W to 74 ± 29 W, P < 0.003). The starting and recovery heart rates were higher after than before dialysis. The peak oxygen uptake (VO(2) peak, VO(2) peak/kg) was reduced from 1.644 ± 600 to 1.422 ± 450 mL/min (P < 0.02) and from 35 ± 7 to 31 ± 5 mL/min/kg (P < 0.03), respectively. The respiratory exchange ratio as well as the lactate values showed significant differences in varied workload levels (P < 0.05). CONCLUSIONS: Paediatric patients on maintenance HD in general have a significantly lower exercise capacity compared to a healthy age-matched population, which is expressed much more after dialysis.

Liver fibrosis in recessive multicystic kidney diseases: transient elastography for early detection.

Cystic renal diseases are characterized by intrarenal cysts of different size and number. Further important diagnostic criteria include, e.g., liver fibrosis. The latter represents a significant cause of morbidity and mortality in autosomal-recessive polycystic kidney disease (ARPKD), whereas patients with autosomal-dominant polycystic kidney disease (ADPKD) can develop hepatic cysts without fibrosis. We report the use of transient elastography [FibroScan®, (FS)] for early and noninvasive detection of increased liver stiffness as marker of liver fibrosis. Compared with matched healthy controls, ADPKD patients (n = 7) showed no significant difference in liver stiffness (5.3 kPa vs. 4.5 kPa; ns). ARPKD patients (n = 7) had significantly increased median liver stiffness compared with controls (12.0 kPa vs. 4.5 kPa, p = 0.002) and ADPKD patients (12.0 kPa vs. 5.3 kPa, p = 0.002). Conventional ultrasound revealed evidence of liver fibrosis in only four of seven ARPKD patients (57%) compared with 100% detection by FS. Additional laboratory examinations showed no pathologic liver parameters. In conclusion, our data found FS to be a valuable, sensitive, and noninvasive new tool for early evaluation of liver fibrosis in cystic kidney diseases. This could facilitate diagnosis, monitoring, and management of liver involvement in ARPKD or any other cystic kidney disease.

Renal allograft calcification -- prevalence and etiology in pediatric patients.

BACKGROUND: Calcification of renal allografts has been reported in adult kidney transplant (KTx) recipients with a widely differing prevalence (2-60%). Persistent hyperparathyroidism, hypercalcemia and concomitant hypercalciuria were identified as major risk factors. We aimed to determine the prevalence and risk factors for such calcifications in children. METHODS: We investigated histological stains of routine graft biopsies from pediatric KTx patients for renal calcifications and determined the urinary excretion of lithogenic (oxalate, calcium) and stone-inhibitory substances (citrate). RESULTS: In our series of transplant patients, tubular calcification was found in 16 of the 36 (44.4%) KTx biopsies by an additional Kossa stain. This transplant calcification was not associated with any singular risk factor and was not correlated to a worse transplant outcome. CONCLUSION: Although our pediatric findings confirm the reported incidence rates of KTx calcification in adults, we could neither identify hypercalciuria as a risk factor nor confirm any negative influence on graft function. However, long-term studies are clearly needed to prove or disprove a negative impact of calcifications on graft function.

Quantitative analyses of SMN1 and SMN2 based on real-time lightCycler PCR: fast and highly reliable carrier testing and prediction of severity of spinal muscular atrophy.

Spinal muscular atrophy (SMA) is a common autosomal recessive disorder in humans, caused by homozygous absence of the survival motor neuron gene 1 (SMN1). SMN2, a copy gene, influences the severity of SMA and may be used in somatic gene therapy of patients with SMA in the future. We present a new, fast, and highly reliable quantitative test, based on real-time LightCycler PCR that amplifies either SMN1 or SMN2. The SMN1 copies were determined and validated in 329 carriers and controls. The specificity of the test is 100%, whereas the sensitivity is 96.2%. The quantitative analysis of SMN2 copies in 375 patients with type I, type II, or type III SMA showed a significant correlation between SMN2 copy number and type of SMA as well as duration of survival. Thus, 80% of patients with type I SMA carry one or two SMN2 copies, and 82% of patients with type II SMA carry three SMN2 copies, whereas 96% of patients with type III SMA carry three or four SMN2 copies. Among 113 patients with type I SMA, 9 with one SMN2 copy lived <11 mo, 88/94 with two SMN2 copies lived <21 mo, and 8/10 with three SMN2 copies lived 33-66 mo. On the basis of SMN2 copy number, we calculated the posterior probability that a child with homozygous absence of SMN1 will develop type I, type II, or type III SMA.