The aim of this study was to define the incidence and characteristics of sclerosing encapsulating peritonitis (SEP) in pediatric peritoneal dialysis (PD) patients in Japan. A questionnaire was sent to all dialysis units with at least two pediatric PD patients. Among 687 patients registered, 11 cases (1.6%) of SEP were diagnosed. The mean age of patients with SEP at the start of PD was 9.7+/-3.6 years and at SEP diagnosis, 19.1+/-3.8 years. All patients had undergone PD for more than 5 years, and the mean PD duration was 9.6+/-3.3 years. SEP was diagnosed in 6.6% and 12% of patients dialyzed for >5 years and >8 years, respectively. The incidence of peritonitis among patients with SEP was not different from that among the Japanese pediatric registry. All patients had virtually no residual urine volume and 9 had impaired peritoneal ultrafiltration. Peritoneal calcification was the most-frequent radiological finding. Peritoneal biopsy was performed in 7 patients and confirmed sclerotic peritonitis in all. Ten patients transferred to hemodialysis, and only 1 patient underwent surgery. Three patients died. We recommend that patients on PD for more than 5 years who have impaired peritoneal ultrafiltration or peritoneal calcification should be carefully managed as presumptive cases of SEP.

Very low birth weight (VLBW) infants can be subjected to oxidative stress in the course of intensive care. We measured 8-hydroxydeoxyguanosine (8-OHdG), a biomarker of oxidative stress, and estimated the degree of oxidative stress in such infants. We also examined if the administered oxygen was related to oxidative stress. Urine samples of 50 Japanese VLBW infants [birth weights: 956.3+/-277.6g, and gestational ages: 28.0+/-2.6 weeks (mean +/- SD)] were collected on various postnatal days and 8-OHdG levels were determined using an ELISA kit. Sixteen term infants served as normal controls. As body weights at sampling increased, the average levels of urinary 8-OHdG decreased. 8-Hydroxydeoxyguanosine levels were: infants under 1000g, 29.5+/-16.4 micromol/mol creatinine (n = 24); 1000-1500g, 23.8+/-14.9 (n = 12); over 1500g, 16.1+/-8.5 (n = 14); and control, 10.9+/-7.2 (n = 16). Significant differences were found between <1000g group and > or = 1500g group (p = 0.0030), <1000g group and control (p < 0.0001), and 1000-1500g group and control (p = 0.0108). Also as postconceptional age at sampling increased, the average levels of 8-OHdG decreased. 8-Hydroxydeoxyguanosine levels were: infants before 252 days (36 weeks) of postconception: 27.4+/-15.5 micromol/mol creatinine (n = 34); after 252 days, 18.2+/-12.5 (n = 16). Differences between <252 days group and control (p < 0.0001), and <252 days group and > or = 252 days groups (p = 0.0253) were statistically significant. Among the three groups based on ambient oxygen concentration (21%, 22-29%, and > or = 30%) there was no significant difference (p = 0.417). The more premature the infants were, the more intense was the oxidative stress, hence, it is the prematurity rather than the administered oxygen which causes oxidative stress in VLBW infants. Drury et al. ["Urinary 8-hydroxydeoxyguanosine in infants and children" Free Radic. Res. 28 (1998) 423-4281 measured urinary 8-OHdG of 28 infants (24-40 weeks gestation) and found no gestation or birthweight related differences. This discrepancy seemed to be because of difference in birth weights and sampling period of the subjects.

Objective Over the past 10 years, we have collected data on pediatric patients less than 16 years of age from the National Registry of CAPD (continuous ambulatory peritoneal dialysis). We present our experience with this population. Design The database details the patient number, age, weight, height, outcome, cause of death, reason for terminating CAPD therapy, peritonitis, and catheter survival. Patients Of the 434 patients (239 males, 195 females), 37 patients (8.5%) were under 1 year of age and 164 patients (37.8%) were under 6 years of age. About half of the patients were less than 20 kg in weight, clearly indicating that CAPD was the treatment of choice in young children. The duration on CAPD for these patients was less than 2 years for 233 patients (54%), and was 5 years or more in 48 patients (11%). Results The outcome of the total patient population of 434 as of M ay, 1991, is as follows 229 patients (52.8%) were being successfully treated with CAPD, 47 patients (10.8%) died, and 78 patients (18.0%) received a kidney transplantation. The patient survival rate was 85.6% at 3 years and 81.7% at 5 years. The technique survival rate was 74.9% at 3 years and 63.5% at 5 years. The rate of peritonitis was one episode over 28.6 patient-months. The mean catheter duration was 1.68 years. Peritonitis rate, catheter survival rate, and the rate of tunnel infection were worse in children less than 6 years of age than in older children. Conclusion The excellent patient and technique survival rates indicate that CAPD is an effective treatment for children with end-stage renal disease in Japan. The high infection rates in younger children indicate that extra careful management is needed for this young age group.

Familial idiopathic low-molecular-weight proteinuria (FILMWP) is a renal proximal tubulopathy that occurs predominantly in males. FILMWP is characterized by mild proteinuria consisting of low-molecular-weight proteinuria, aminoaciduria and relatively conserved renal function, but without rickets. To determine whether FILMWP is related to the CLCN5 gene, which is responsible for Dent's disease and two related disorders, we analyzed the CLCN5 gene from four Japanese families with FILMWP. We identified two novel mutations: one was a single base insertion at codon 520 serine in exon 10 and the other was a single base deletion at codon 403 tyrosine in exon 8. These mutations caused a shift in the reading frame, resulting in synthesis of truncated CLC5 proteins that lacked 220 (29%) and 314 (42%) amino acids, respectively. These mutations were demonstrated to cosegregate with the disease in two families, respectively. We conclude that the CLCN5 gene is responsible for this proximal renal tubulopathy in some Japanese families and that FILMWP is possibly a variant of Dent's disease.

We conclude that the CLCN5 gene is responsible for the renal proximal tubulopathy in many Japanese families and suggest that molecular defects, environmental factors, or other modifying genes may account for the different phenotypes.

22 patients with IgA nephropathy aged 7–16 years, 15 of whom were found by mass urine screening of school children, were divided into three groups based on the degree of their proteinuria at admission: group A (n = 6) below 0.5 g/day of urine protein, group B (n = 7) between 0.6 and 3.0, and group C (n = 9) above 3.0 g/day of urine protein. The degree of proteinuria seemed to be related to the severity of pathological changes of the glomerular basement membrane; most severe in group C, moderate in group B, and minimal in group A. IgA deposits in the mesangial area were found in all groups of patients, but those in the capillary walls were most frequently found in group C. In addition to electron-dense deposits in the mesangial area, which was found in all groups of patients, the subendothelial and subepithelial deposits were the most remarkable changes found in group C. During the clinical observation period, which was between 2.0 and 7.1 years, no patient belonging to group A progressed to groups B or C. 4 cases in group C developed chronic renal failure, but none in the other groups did. The amount of urine protein might be used as a valuable parameter of the pathological damage of the glomerulus in children with IgA nephropathy.

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Urinary abnormalities combined with positive serum hepatitis B virus surface antigen (HBsAg) were found in 9 children. Most of these patients were found by mass urine screening of school children. Renal biopsy findings revealed 6 cases of membranous glomerulonephropathy (MGN) and 3 cases of minimal change disease. Immune deposits consisting of hepatitis B virus e antigen (HBeAg), IgG and C₃ were detected in the glomerular capillary walls by immunofluorescent study in patients with MGN. Circulating immune complex was positive at a rate of 67% (6/9 cases) by the C_1q-binding assay and at a rate of 56% (5/9 cases) by the protein-A precipitation test in patients with persistent urinary abnormalities and hepatic dysfunction.