Indomethacin,ibuprofen and gentamicin administered during late stages of glomerulogenesis do not reduce glomerular number at 14 days of age in the neonatal rat

Premature neonates are frequently administered indomethacin, ibuprofen and gentamicin during the period of active glomerulogenesis. These drugs are known to have nephrotoxic effects, but the morphological effect of these drugs is unknown. The purpose of this study was to determine whether administration of these drugs during the late stages of glomerulogenesis in the rat has an effect on glomerular endowment. Rat pups were given, intraperitoneally, indomethacin, ibuprofen or indomethacin and gentamicin for the first 5 days of their postnatal life. The pups were killed at 14 days of age at completion of glomerulogenesis. The total number of glomeruli in the left kidney was determined by the physical disector/fractionator stereological technique. There was no difference between treatment groups in total number of glomeruli per kidney (P = 0.45). There were significantly fewer glomeruli per gram of kidney in those rat pups that had received indomethacin or ibuprofen (P < 0.0001). The reduction in the number of glomeruli per gram of kidney may indicate augmented growth of nephron tubules and/or collecting ducts, and/or be a consequence of oedema secondary to drug exposure. Further study is required to determine whether reduced glomerular number is seen in older animals or following exposure to these drugs at different time-points in kidney development.     

Histopathological evidence of poor prognosis in patients with vesicoureteral reflux

Patients with vesicoureteral reflux (VUR) often develop reflux nephropathy with focal segmental glomerular sclerosis (FSGS), although the exact mechanisms leading to the development of this complication are unknown. To determine the early changes in glomeruli of VUR patients that ultimately cause poor renal outcome, we examined morphometrically renal biopsies of 16 young patients (age 10–20 years) with VUR at baseline pre-operatively. Patients were divided into two groups, those who subsequently showed good prognosis and those with poor renal prognosis at the end of a 10-year follow-up period. Patients with poor prognosis had worse proteinuria and lower creatinine at baseline than those with good prognosis. We also examined 40 age-matched control cases with previous temporal microhematuria and/or proteinuria but normal renal function and histology. Although the mean diameter of glomerular capillary did not change in VUR cases irrespective of prognosis, glomerular capillary length increased by 125% in cases with good prognosis, and 335% in cases with poor prognosis (P<0.01). Cystically expanded capillaries, with diameter ≥95% of that in age-matched control, were detected in five of eight patients with poor prognosis, but only in one of eight patients with good prognosis. In VUR, the number of podocytes/capillary diminished with increased length of the capillaries. Tuft adhesion to Bowman’s capsule and podocyte detachment were primarily found in patients with poor prognosis. Our results suggest that lengthening of glomerular capillaries in young patients with VUR is a compensatory reaction to hyperfiltration. The appearance of cystic capillary expansion, podocyte detachment and/or tuft adhesion to Bowman’s capsule in such glomeruli may be important indicators of renal prognosis in patients with VUR. These changes may lead to FSGS due to podocyte injury in patients with VUR, with subsequent deterioration of renal function. Received: 3 January 2000 / Revised: 18 January 2001 / Accepted: 18 January 2001     

Oligonephronia, not exuberant apoptosis, accounts for the development of glomerulosclerosis in the bcl-2 knockout mouse

Background. A main function attributed to B cell leukaemia/lymphoma 2 gene (bcl-2) is its ability to confer resistance against apoptosis. In bcl-2 deficient mice, extensive apoptosis occurs during abnormal nephrogenesis, and renal failure is found very quickly after birth. However, the underlying mechanisms remain poorly understood. The aim of the present study was to clarify whether the degenerative process in the kidneys seen after birth is based either on increased apoptosis of glomerular cells or on mechanisms independent from the genetic defect. Materials and methods. Kidneys from 7-56-day-old bcl-2 knockout mice and wild-type litter mates were studied. Glomerula number, glomerular tuft volume, cell counts in 'non-sclerotic' glomeruli as well as the glomerular damage score were determined by histomorphometrical studies. Apoptosis was evaluated by morphological criteria and the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labelling (TUNEL)-technique. Results. The number of nephrons at birth was severely decreased in bcl-2 knockout mice compared to controls (<20%; P<0.001). These nephrons undergo dramatic hypertrophy with an approximately 4-fold increase in volume (P<0.001). In hypertrophic, but 'non-sclerotic' glomeruli, the number density of glomerular cells progressively declined with time (P<0.001). Starting with day 20, enlarged glomeruli developed sclerosis beginning with a segmental distribution, but quickly progressing to global sclerosis. Apoptosis was neither detected in non-sclerotic glomeruli nor in stages prior to fully established sclerosis. As shown by the glomerular damage score, post-natal degeneration of kidneys from bcl-2 knockout animals proceeded rapidly. Conclusions. Bcl-2 knockout mice exhibit deficient nephrogenesis resulting in severe oligonephronia at birth. Post-partum development of glomerulosclerosis does not seem to be due to augmented apoptosis. The degenerative process appears to be based on a glomerular overload with increased mechanical stress to the filtration barrier, leading via glomerula hypertrophy, podocyte damage and formation of tuft adhesions to glomerulosclerosis.     

Glomerular eNOS gene expression during postnatal maturation and AT1 receptor inhibition

Glomerular maturation increases from immature superficial to advanced juxtamedullary nephrons, while nephrogenesis continues postnatally in porcine kidneys. Endothelial NOS, eNOS, shows significant postnatal renal developmental regulation, perhaps mediated by Angiotensin II (AII). The objective was to compare eNOS mRNA gene expression between superficial and juxtamedullary glomeruli obtained from piglets and adult pigs utilizing laser capture microdissection during basal conditions and, to determine the role of the AII AT1 receptor, AT1, after chronic AT1 inhibition (AT1X) with candesartan. Superficial glomerular eNOS expression was lowest in newborns (NB) and at 7 days, and was highest in 14, 21 day old piglets and adults. Juxtamedullary glomerular eNOS, while similar in NB, 14, 21 day and adult, dipped to the lowest level at 7 days. Juxtamedullary glomerular eNOS expression in the NB was 7 fold greater than in superficial glomeruli. AT1X did not change eNOS expression in adult glomeruli. AT1X significantly reduced NB eNOS expression in both superficial, 90 ± 10%, and juxtamedullary glomeruli, 89 ± 5% respectively. In conclusion, eNOS gene expression demonstrates significant differences between NB superficial and juxtamedullary glomeruli, significant postnatal developmental regulation of both glomerular locations, and this expression may be mediated in the NB by AII via the AT1 receptor.     

Six-minute walking test in children with ESRD: discrimination validity and construct validity

The six-minute walking test (6MWT) may be a practical test for the evaluation functional exercise capacity in children with end-stage renal disease (ESRD). The aim of this study was to investigate the 6MWT performance in children with ESRD compared to reference values obtained in healthy children and, secondly, to study the relationship between 6MWT performance with anthropometric variables, clinical parameters, aerobic capacity and muscle strength. Twenty patients (13 boys and seven girls; mean age 14.1 ± 3.4 years) on dialysis participated in this study. Anthropometrics were taken in a standardized manner. The 6MWT was performed in a 20-m-long track in a straight hallway. Aerobic fitness was measured using a cycle ergometer test to determine peak oxygen uptake ( \textV^· \textO_\text2peak ) \left( {\mathop {\text{V}}\limits^\cdot {{\text{O}}_{\text{2peak}}}} \right) , peak rate (W_peak) and ventilatory threshold (VT). Muscle strength was measured using hand-held myometry. Children with ESRD showed a reduced 6MWT performance (83% of predicted, p < 0.0001), irrespective of the reference values used. The strongest predictors of 6MWT performance were haematocrit and height. Regression models explained 59% (haematocrit and height) to 60% (haematocrit) of the variance in 6MWT performance. 6MWT performance was not associated with \textV^· \textO_\text2peak {\mathop {\text{V}}\limits^\cdot {{\text{O}}_{\text{2peak}}}} , strength, or other anthropometric variables, but it was significantly associated with haematocrit and height. Children with ESRD scored lower on the 6MWT than healthy children. Based on these results, the 6MWT may be a useful instrument for monitoring clinical status in children with ESRD, however it cannot substitute for other fitness tests, such as a progressive exercise test to measure \textV^· \textO_\text2peak {\mathop {\text{V}}\limits^\cdot {{\text{O}}_{\text{2peak}}}} or muscle strength tests.     

Risk factors for renal insufficiency in children with urethral valves

Posterior urethral valves (PUV) associated with renal dysplasia are one of the most common causes of end stage kidney disease (ESKD) in childhood. In order to identify risk factors for the progression of this condition to early renal failure, we have retrospectively analyzed the clinical course, renal function, and first postnatal renal ultrasound in a sample of 42 young male patients with PUV, who were followed at a single center. Twelve (28.6%) were diagnosed with ESKD at a median age of 11.3 years. Our comparison of PUV patients without decreased estimated glomerular filtration rate (eGFR) (group A; K/DOQI CKD stage 0–1) with PUV patients showing a decreased eGFR (group B; K/DOQI CKD stage 2–5) revealed the following significant risk factors for loss of eGFR: renal volume <3rd percentile (P < 0.001), elevated echogenicity (P = 0.001), pathologic corticomedullary differentiation (P < 0.001), >3 febrile urinary tract infections (P = 0.012), and decreased eGFR at 1 year of age (P < 0.001). Receiver operating characteristic curve analysis in the cohort confirms that patients showing a renal volume >88.2 ml/m² body surface area (BSA) are not at risk to develop K/DOQI CKD stage 5 (sensitivity 75%, specificity 77.3%, positive/negative predictive value 37.5/94.4%). Ultrasound promises to be a valuable tool for identifying endangered patients.     

Development of a beta-trace protein based formula for estimation of glomerular filtration rate

Beta-trace protein (BTP) is a novel marker of glomerular filtration rate (GFR). To date, no pediatric formula for calculating GFR based on BTP has been developed. We measured GFR, serum creatinine and BTP in 387 children who underwent 474 ^99mTc-diethylene triamine pentaacetic acid renal scans. A BTP-based formula for estimating GFR was derived using stepwise linear regression analysis. A separate control group of 116 measurements in 99 children was used to validate the novel formula. A formula was also developed for each gender. The novel formula is: \textGFR = \text10^ù (\text1.\text90\text2 + ( 0.\text9515 x LOG( \text1/\textBTP ) ) ) {\text{GFR}} = {\text{1}}{0^\wedge }\left({\text{1}}.{\text{9}}0{\text{2}} + \left( {0.{\text{9515 x LOG}}\left( {{\text{1}}/{\text{BTP}}} \right)} \right) \right) . The Spearman rank correlation coefficient between the BTP-derived GFR estimate and the measured GFR was 0.80 [95% confidence interval (CI) 0.76–0.83], which is substantially better than that derived with the Schwartz formula (r = 0.70, 95% CI 0.65–0.74). The Bland–Altman analysis revealed a mean bias of 1.21% [standard deviation (SD) 28%] in the formula development dataset, which was virtually identical to the 1.03% mean bias (29.5% SD) in the validation group and no different from the Schwartz formula bias. The percentage of values within 10% (33.0 vs. 28.3%) and 30% deviation (76.8 vs. 72.6%) were better for BTP-based formula than for the Schwartz formula. Separate formulas according to gender did not perform better than that for the pediatric population. This BTP-based formula was found to estimate GFR with reasonable precision and provided improved accuracy over the Schwartz GFR formula.     

Urinary transforming growth factor beta1 in children and adolescents with congenital solitary kidney

The aim of the study was to assess urinary transforming growth factor beta1 (TGF beta1) level in children and adolescents with congenital solitary kidney (CSK), depending on estimated glomerular filtration rate (eGFR) and compensatory overgrowth of the kidney. The study group (I) consisted of 65 children and young adults, 0.5–22 years of age (median 10.0 years) with CSK and no other urinary defects. The control group (C) contained 44 healthy children and adolescents, 0.25–21 years old (median 10.3 years). We used an enzyme-linked immunosorbent assay (ELISA) to determine the urinary level of TGF beta1, the Jaffe method to assess creatinine concentration, and the Schwartz formula to estimate GFR. Kidney length was measured while the patient was in a supine position, and overgrowth (O%) was calculated with reference to the charts. Urinary TGF beta1 level in CSK patients was more than twice as high as that in controls (P < 0.05). Also, eGFR in patients with CSK exceeded the values in the control group (P < 0.01). Compensatory overgrowth of the solitary kidney was found (median 19.44%). Urinary TGF beta1 concentration was positively correlated with eGFR (r = 0.247, P < 0.05), uric acid concentration (r = 0.333, P < 0.01), and percentage of overgrowth (r = 0.338, P < 0.01) and body mass index (BMI) centile (r = 0.274, P < 0.05). We concluded that, although proteinuria and progressive renal insufficiency is not observed in patients with CSK during childhood, the renal haemodynamic changes are present and may be a risk factor for impairment of renal function and hypertension in future life.     

Thrombospondin-1 in Patients with Diabetic Nephropathy

Thrombospondin-1 (TSP-1), a potent antiangiogenic and proatherogenic protein, has been implicated in the development of several vascular diabetic complications. The aim of the study is to find the role of TSP-1 in diabetic nephropathy. We investigated serum TSP-1 in 30 patients with type 2 diabetes mellitus and diabetic nephropathy (group 1) with renal disease grade 1 to 3 (Kidney Disease Outcomes Quality Initiative stages of kidney disease) and 15 normal control subjects (group 2). Thorough history and clinical examination, biochemical tests including renal function tests, renal ultrasound and renal artery Doppler were done to the studied groups. In addition, carotid intima media thickness and serum TSP-1 enzyme-linked immunosorbent assay were measured. Serum TSP-1 was increased in diabetic nephropathy (193.33 ± 43.28) ng/ml compared to controls (106.27 ± 38.80) ng/ml (p < 0.001). TSP-1 correlates negatively with glomerular filtration rate (p < 0.001) and positively with resistivity index (RI) of extrarenal vessels (p < 0.001) and RI intrarenal vessels (p < 0.001). There is also positive correlation between serum TSP-1 with age (p = 0.004) and carotid intima media thickness (p = 0.004). No correlation was found with proteinuria (p = 0.37). Linear regression test in group 1 shows TSP-1 is significant independent determinant for glomerular filtration rate (p < 0.001) and carotid intima media thickness (p = 0.002). The present study suggests that TSP-1 plays an important role in development of complications in Patients with diabetic nephropathy. Serum level of TSP-1 is related to renal injury and vascular disease. Further studies may be necessary to determine casual relationship between TSP-1 and renal damage and to determine the role of targeting TSP-1 in managing these complications and preventing its progress.     

Clinical, histopathological and flow-cytometric properties of incidental renal cell carcinomas

Medical records of 63 patients operated on for renal cell carcinoma (RCC) between 1986 and 1996 in the Karlovac General Hospital were studied retrospectively. In 23 (36.5%) patients, the tumor was incidentally detected. The median patient age was 62 in the incidental group and 64 years in the symptomatic group (P > 0.05). Ultrasonography was the leading technique for incidental detection of RCC. The median tumor diameter was 6 cm in the incidental group and 9 cm in the symptomatic group (P < 0.001). Incidental carcinomas had a lower stage (P = 0.022) and a lower nuclear grade (P < 0.001) than the symptomatic ones. The incidental cases were associated with a more favorable ploidy status (P = 0.027) and a lower proliferative activity (P = 0.005). The 5-year survival rate was significantly higher in incidental (81.4%) than in symptomatic cases (44.3%) (P = 0.020). Univariate analysis showed that tumor stage, ploidy status, and proliferative activity were good prognostic parameters, while patient age, tumor size, and nuclear grade were not. Tumor stage was the only independent prognostic parameter in multivariate analysis. In conclusion, the incidentally detected RCC show more favorable clinical, histopathological, and flow-cytometric characteristics and their prognosis is significantly better than in symptomatic cases. Received: 21 July 1998 / Accepted: 1 July 1999     

Pre-pubertal induction of experimental diabetes protects against early renal macrophage infiltration

The present study was undertaken to identify whether the age at induction of experimental diabetes modifies macrophage infiltration in the kidney. Renal macrophage infiltration was studied 10 days after the induction of experimental diabetes in 4-week-old pre-pubertal and 12-week-old adult male rats of normotensive [Wistar-Kyoto (WKY) rats] and hypertensive (spontaneously hypertensive rats, SHRs) background. Renal macrophage infiltration was evaluated by immunohistochemistry for ED1. Plasma glucose levels were similar in all diabetic groups. Adult SHRs were hypertensive, and induction of diabetes did not alter blood pressure (BP) in any group. Induction of diabetes in pre-pubertal rats did not induce macrophage infiltration in the kidney. However, in adult rats, tubulointerstitial macrophage infiltration was increased in both WKY (22.86 ± 3.93 vs 7.86 ± 2.16 per high-power field, P < 0.001) and SHR (26.41 ± 5.91 vs 11.48 ± 1.23, P < 0.001) groups after induction of diabetes. Glomerular macrophage infiltration was also increased after induction of diabetes in the adult WKY group (1.83 ± 0.50 vs 1.16 ± 0.26 per glomerular cross section, P = 0.029), which was not significant in the adult SHRs (2.52 ± 0.34 vs 1.95 ± 0.35). We conclude that the pre-pubertal induction of diabetes apparently protects against early renal macrophage infiltration, while the induction of diabetes in adults induces exaggerated macrophage infiltration in the kidney.     

Expression of Ki-67 antigen using monoclonal antibody MIB-1 in children with post-streptococcal glomerulonephritis

We investigated the expression of Ki-67 antigen using monoclonal antibody MIB-1 in glomeruli and renal tubules of 21 children (18 males, 3 females) with post-streptococcal glomerulonephritis (PSGN). Patients were divided into two groups of active and convalescent phases. The active group (n=13) comprised those patients with clinical manifestations of the acute nephritic syndrome consisting of edema, hypertension, hematuria, and oliguria or those in whom percutaneous renal biopsy was performed within 4 weeks of onset of the symptoms of PSGN and those with serum C3 levels below 55 mg/dl at the time of biopsy. MIB-1 expression was considered positive when staining of endocapillary cells was observed. Of the 21 biopsies, expression of MIB-1 in glomeruli and renal tubules was observed in 14 cases (63.6%) and 20 cases (95.7%), respectively. The expression of MIB-1 in glomeruli of patients with active disease (11/13, 84.6%) was significantly higher than that of the convalescent group (2/8, 25%) (P=0.018). The cellularity in the glomeruli was more severe in the active group than the convalescent group (P=0.0475). There was a significant difference of neutrophilic infiltration in glomeruli between the active group and the convalescent group (P=0.0117). However, glomerular MIB-1 expression did not correlate with the degree of immunofluorescence, the number of neutrophils in the glomeruli on light microscopy, and the presence of subepithelial dense deposits on electron microscopy. There was no significant correlation between MIB-1 and serum C3 level. There was no significant correlation between glomerular MIB-1 expression and creatinine clearance (r=–0.180, P=0.556) or 24-h urinary protein excretion (r=0.434, P=0.137). Our results suggest that the expression of MIB-1 in glomeruli in the active phase in PSGN was higher than in the convalescent phase and expression of glomerular MIB-1 appears to be related to glomerular endocapillary proliferation with exudative lesions in children with PSGN. Received: 20 October 1998 / Revised: 27 July 1999 / Accepted: 30 July 1999     

Carnitine as a preventive agent in experimental renal ischemia-reperfusion injury

Reactive oxygen species generated during the reperfusion of ischemic kidney, as well as any other tissue, cause lipid peroxidation damaging the cell membrane. The aim of this study was to investigate the effect of carnitine in reperfusion injury of the kidney. Male albino rabbits were subjected to unilateral renal 1-h warm ischemia followed by 15 min of reperfusion. Group I (n=9): control group received 3 cc of isotonic saline solution and group II (n=9): carnitine group received 100 mg/kg of carnitine. Blood samples were collected at the 15th min of reperfusion from the left renal vein selectively. Preischemic and post-reperfusion serum and renal tissue MDA levels were measured by thiobarbituric acid reactive substances (TBARS) spectrophotometric analysis. The preischemic serum and tissue MDA values (sham values) for groups I and II were statistically comparable (P > 0.01). Serum and tissue MDA levels were markedly elevated after 15 min of reperfusion in group I (P < 0.01), while the values remained in the baseline levels following reperfusion in group II (P > 0.01). In group I, the major histological differences observed in the reperfused kidneys were marked edema and congestion whereas glomerular and tubular cellular integrity were well preserved in group II. Pre-treatment with carnitine in solid organ transplantations, preschock states, surgical procedures that require temporary vascular clamping etc. may be helpful to minimize the reperfusion injury in the involved tissue, reducing morbidity and mortality. Received: 22 May 2000 / Accepted: 1 February 2001     

Obesity and preterm birth: additive risks in the progression of kidney disease in children

Preterm birth is associated with decreased nephron mass and obesity that may impact on kidney disease progression in later life. Our objectives were to examine the relative risks of obesity and preterm birth on the progression of kidney disease in children. In a retrospective cohort study, 80 (44 obese and 36 non-obese) patients with proteinuric kidney disease were studied for disease progression and glomerular histomorphometry. Of the obese, 22 had been born at term (Obese-T) and 22 had been preterm (Obese-PT). Seventeen non-obese children with focal glomerular sclerosis, born at term (NO-FSGS), and 19 non-obese preterm (NO-PT) children, served as controls. Insulin resistance as measured by the homeostatic model assessment (HOMA-IR) was elevated in all obese children. Obese-PT patients had increased risk of renal demise during childhood when compared with Obese-T children [hazard ratio 2.4; 95% Confidence interval (95% CI) 1.1 to 7.1; P = 0.04]. In obese children, although proteinuria often exceeded nephrotic range, average levels of serum albumin remained normal. Preterm patients were more likely to have reduced renal mass (odds ratio 4.7; P = 0.006), but obesity was not a factor. Renal histomorphometry showed glomerulomegaly in obese patients, regardless of birth weight. Obesity and preterm birth appear to impose additive risks for progression of kidney disease in childhood.     

Histology of the fetal prune belly syndrome with reference to the efficacy of prenatal decompression

BACKGROUND: Deficient abdominal musculature, complex abnormalities of urinary tracts and bilateral abdominal cryptorchidism represent the basic characteristics of prune belly syndrome (PBS). Although prenatal diagnosis of PBS is rarely made, because of the wide variety of ultrasonographic images, reported cases have gradually increased. Once a fetus suspected of having PBS is found, it is sometimes difficult for the pediatric urologists to decide how to treat them. The histology of the kidney and urinary tracts in fetuses with PBS was reviewed in order to give suggestions on the management of prenatal cases. METHODS: Autopsy records of nine fetuses (5 males, 2 females and 2 undetermined) with characteristically distended and deficient abdominal wall were reviewed. Gestational age (GA) at detection ranged from 12 to 25 weeks and at delivery from 13 to 32 weeks. RESULTS: Renal histology in two fetuses showed earlier than normal disappearance of cortical nephrogenic zone replaced by cortical cysts and dysplastic structures. The nephrogenic zone was retained in five fetuses which were younger than GA 20 weeks. While the number of glomeruli along the medullary ray was normal for the age in three fetuses younger than GA 20 weeks, it was decreased in all others. Bladder histology was variable showing both increased musculature and defective or dysplastic muscles. There was a tendency for connective tissues in the bladder wall to increase in proportion to GA, The ureter revealed scarcity of muscle bundles among dense connective tissue. The urethra was atretic in eight fetuses. CONCLUSION: The clinical implication from the renal histology is that decompression of the urinary tract should be done before GA 20 weeks. However, the early fetal treatment appears to have no effect on the urodynamics in this disorder with deficient musculature.     

Serum cystatin C for estimation of residual renal function in children on peritoneal dialysis

Residual renal function (RRF) is an important parameter in the management of patients on chronic dialysis. The aim of this cross-sectional study was to determine the efficacy of serum cystatin C (CysC) for RRF estimation in 20 children (16 boys, 4 girls; median age 13.4 years) undergoing peritoneal dialysis (PD). For studies of correlation with serum CysC, the average of creatinine clearance rate (C_cr) and urea clearance rate (C_urea), Kt/V_urea, and weekly C_cr were evaluated as parameters reflecting RRF. The serum CysC level was found to be negatively correlated with urine volume (r = −0.717, P < 0.001), average of C_cr and C_urea(r = −0.851, P < 0.001), total and renal weekly C_cr (r = −0.795, P < 0.001; r = −0.845, P < 0.001, respectively), and renal Kt/V_urea (r = −0.793, P < 0.001) and positively correlated with peritoneal weekly C_cr (r = 0.738, P < 0.001) and peritoneal Kt/V_urea (r = 0.785, P < 0.001). There was no significant association with total Kt/V_urea (r = −0.335, P = 0.148). In non-anuric group of patients, serum CysC had no link to peritoneal Kt/V_urea (r = 0.573, P = 0.066), but was negatively correlated with renal Kt/V_urea (r = −0.609, P = 0.047). In the multiple regression analysis, renal Kt/V_urea significantly contributed to log CysC concentration rather than peritoneal Kt/V_urea. The results of this study suggest that serum CysC could be an appropriate marker for RRF, independent of total and peritoneal Kt/V_urea.     

A novel surgical organ perfusion method for effective ex vivo and in vivo gene transfer into renal glomerular cells

In an attempt to develop gene therapy for Alport syndrome, we have evaluated surgical methods for gene transfer into pig kidneys. For gene transfer we used an adenovirus expressing the Escherichia coliβ-galactosidase gene as a reporter gene. The viral preparation was first infused in vivo into the porcine renal artery. Then explanted kidneys were perfused ex vivo at body temperature for 12 hours with the viral solution and, finally the kidney perfusions were carried out in vivo via laparotomy for 60 and 120 minutes. Gene transfer was determined visually on histological cryosections after 5-bromo-4-chloro-3-indoyl-β-galactopyranoside (X-gal) and periodic acid-Schiff (PAS) staining. Perfusion of whole porcine kidneys ex vivo resulted in strong expression in about 80% of glomeruli. The in vivo kidney perfusion via laparotomy for 120 minutes resulted in reporter gene expression of about 75% of the glomeruli examined after 4 days. Expression was observed almost exclusively in glomeruli, while little if any expression was found in other renal structures. The present results suggest that operatively performed kidney perfusion may be used for gene transfer in treatment of glomerular disease. This surgical approach may also prove useful for somatic gene therapy of other organs. Received: 23 April 1998 / Accepted: 25 September 1998     

Bicarbonate therapy improves growth in children with incomplete distal renal tubular acidosis

Incomplete distal renal tubular acidosis (idRTA) has recently been associated with osteoporosis and growth retardation, attributed to the mild persistent metabolic acidosis. We hypothesized a therapeutic benefit from bicarbonate therapy on growth parameters in children with idRTA. In a study group of 40 surgically treated patients with posterior urethral valve (PUV) and normal estimated glomerular filtration rate, we evaluated the change in height standard deviation scores (SDSs) while they were on bicarbonate therapy in the presence of idRTA and complete distal renal tubular acidosis (dRTA). Age- and gender-matched healthy subjects constituted the control group (n = 55). Incomplete dRTA was evaluated by ammonium chloride acidification. The baseline height SDS of −1.94 ± 0.41 and −5.31 ± 1.95 in the groups with idRTA and complete dRTA, respectively, were significantly lower than that of the controls. After a follow-up period of 24.7 ± 8.3 months on sodium bicarbonate therapy, the idRTA patients had a 66% increase in height SDS compared with 26% and 3% increases in the patients with PUV with complete dRTA and without dRTA, respectively. At the end of follow-up, mean height SDS in the group with idRTA no longer remained significantly lower than that of the controls (P = 0.42). We concluded that bicarbonate therapy improves height SDS in idRTA. This issue needs further validation in larger studies.