Changes in body composition of children with chronic renal failure on growth hormone.

Body composition is altered in children with chronic renal failure (CRF) and contributes to the significant growth failure seen in these children. Recombinant human growth hormone (rhGH) has been used in the past several years to improve the somatic growth of children with CRF. To determine if the growth achieved in these children occurs concomitantly with body compositional changes, seven prepubertal (n=6) and pubertal (n=1) children with chronic renal insufficiency (n=4) and end-stage renal disease (n=3) underwent measurements of total body fat (FM), fat free mass (FFM), bone mineral density (BMD), total bone mineral mass (TBBM), total body water (TBW), and total body potassium (TBK) before and 6 months after initiation of subcutaneous recombinant human growth hormone (rhGH) at 0.35 mg/kg per week. The techniques used included dual-energy X-ray absorptiometry (for measurement of FM, BMD, and TBBM), total body potassium counting (for measurement of TBK), and deuterated water for assessment of TBW. Significant increases in both height and weight were seen following 6 months of rhGH therapy. These increases were accompanied by significant reductions in FM (4.4+/-1.4 kg vs. 3.6+/-1.2 kg, P=0.002) and percentage fat (18.6+/-3.9% vs. 14.5+/-3.4%, P=0.04), while FFM (17.9+/-3.0 kg vs. 20.7+/-3.6 kg, P=0.04) increased significantly as did TBBM (776+/-171 g vs. 844+/-177 g, P=0.001). Increases in TBK, a measure of body cell mass, were also seen. No difference in total BMD was observed. Thus, growth in CRF is occurring with repletion of the FFM and TBBM compartments. Despite these improvements, no change was observed in the body mass index (BMI). Measurement of BMI alone does not define the compartmental catabolic losses in FFM.

Advanced glycosylation end-products and NO-dependent vasodilation in renal afferent arterioles from diabetic rats.

Systemic pressor responses to acetylcholine (ACh) are reduced in DM, an effect thought to be related to quenching of nitric oxide (NO) by advanced glycosylation end-products (AGE). We studied the effects of AGE in juxtamedullary (JM) afferent arterioles (AA) from rats with 40-50 days diabetes mellitus (DM) induced via streptozotocin. JM AA were perfused in vitro with solutions containing fresh RBCs suspended in either 6% bovine albumin or 6% AGE-albumin in euglycaemic Krebs-Ringer. Autoregulatory responses were evident in the DM vessels: AA constricted 31 +/- 2% (n=9) when perfusion pressure (PP) was raised from 60 to 140 mmHg. ACh (10 microM) caused a 43 +/- 15% dilation and Ca2+-channel blockade elicited a 95 +/- 14% dilation at 100 mmHg PP, indicating substantial basal vascular tone in DM AA. L-NAME (0.1 mM) constricted DM AA by 21 +/- 2% (n=9) at 100 mmHg PP, indicating significant basal NO production in DM vessels. Segments of renal resistance arteries from DM rats perfused in vitro responded to muscarinic stimulation and elevated glucose levels with significant increments in NO production, as measured with an NO-sensitive electrode. This observation shows that the renal endothelial NO system is intact in DM. While AGE in the perfusate dilated control AA, they had no effect on DM AA at all PP levels, although they blunted ACh-induced dilation. Hence, although AGE do appear to have vasoactive properties in the absence of hyperglycaemia, the results of this study are inconsistent with substantial NO quenching by AGE.

Peritoneal loss of insulin-like growth factor-I and binding proteins in end-stage renal disease.

The kinetics of peritoneal transport of insulin-like growth factor (IGF) system-related proteins during dialysis is not well characterized. We studied temporal changes in dialysate and serum concentrations of IGF-I and IGF-II as well as IGF binding protein (BP)-1, -2, and -3 in ten children with end-stage renal disease (ESRD) undergoing continuous cycling peritoneal dialysis (CCPD) during a 4-h peritoneal equilibration test (PET). Dialysate concentrations of IGF-I, IGF-II, and all three IGFBPs demonstrated a time-dependent increase during PET. Despite their transport, the serum concentrations of these proteins did not change significantly during the PET. Dialysate/serum ratios for IGF-I, IGF-II, and IGFBP-1, -2, and -3 were significantly increased at 2 h and increased further at 4 h, at which time values averaged 1.3+/-0.2%, 3.1+/-0.5%, 6.2+/-1.0%, 2.4+/-0.2%, and 1.3+/-0.2% of serum levels, respectively. The transperitoneal clearance (microl/min per 1.73 m2) of the three IGFBPs was inversely related to both their molecular weight and plasma concentration. However, peritoneal clearance of IGF-I and -II was similar to that of the larger and more-abundant IGFBP-3. Mass transfer rates (microg/h per 1.73 m2) for the IGFs and their binding proteins were directly proportional to their prevailing plasma concentration. Based on estimates of mass transfer, only a small molar excess of IGFBPs was removed from the circulation relative to the combined molar concentration of IGF-I and IGF-II. Hence, it seems unlikely that any beneficial effect of CCPD on growth in children with ESRD is mediated via a preferential loss of IGFBPs into the dialysate fluid.

Insulin-like growth factor-I restores microvascular autoregulation in experimental chronic renal failure.

Impairment of autoregulation (AR) is associated with accelerated progression of chronic renal failure (CRF). As the bioavailability of insulin-like growth factor-I (IGF-I) is low in CRF, we investigated the effects of acute luminal application of 10 nM recombinant human IGF-I on AR in juxtamedullary (JM) afferent arterioles (AA) perfused in vitro with a blood solution [(approximately 30% hematocrit (HCT)]. Studies were conducted in AA from adult male rats three to four weeks after five-sixths nephrectomy (Nx) by either surgical excision (N = 7) or infarction (N = 5) of two thirds of the remnant kidney; controls (N = 6) had sham surgery. AA from both Nx groups exhibited marked hypertrophy and impaired AR responses (60 to 140 mm Hg perfusion pressure), features more pronounced in the infarction group. Responses to abluminal acetylcholine (10 microM) were similar in sham and excision groups but were significantly blunted in the infarction group. All groups vasodilated significantly after Ca-channel blockade (10 mM MnCl2). IGF-I restored AR in AA from both Nx groups (P < 0.05, analysis of variance) while it vasodilated AA from controls. These results suggest that IGF-I may protect the glomerulus from injury by maintaining autoregulatory control of renal blood flow, thereby slowing the progression of CRF.

Effects of insulin-like growth factor I on the renal juxtamedullary microvasculature.

To characterize the effects on the rat renal preglomerular microvasculature of insulin-like growth factor I (IGF-I), experiments were performed using the in vitro blood-perfused juxtamedullary nephron preparation. IGF-I induced a reversible vasodilation of pre- but not postglomerular microvessels in a dose-dependent manner (10(-9)-10(-7) M). The IGF-I-induced vasodilation was similar in all preglomerular vascular segments: interlobular artery, 11.5 +/- 1.2% of control (n = 16); mid-afferent arterioles, 11.6 +/- 1.7% (n = 24); and juxtaglomerular afferent segments, 16.1 +/- 2.8% (n = 19). Renal autoregulatory capacity was not reduced by IGF-I. Pretreatment with the nitric oxide (NO) synthase inhibitor NG-nitro-L-arginine methyl ester (10(-4) M) completely inhibited the vasodilatory response to IGF-I. IGF-I induced a rapid increase of NO concentration in intact renal microvessels, monitored by a NO-selective voltametric microelectrode. Pretreatment with the cyclooxygenase inhibitor indomethacin (10(-5) M) not only abrogated the IGF-I-induced dilation, but, moreover, IGF-I elicited a small but significant (approximately 10%) vasoconstriction in all preglomerular vessels. These results indicate that the renal vascular effects of IGF-I involve activation of two endogenous vasodilators (NO and vasodilatory prostaglandins). In addition, IGF-I may also release an undefined vasoconstrictor.

Decreased hepatic insulin-like growth factor (IGF)-I and increased IGF binding protein-1 and -2 gene expression in experimental uremia.

The imbalance between normal insulin-like growth factor-I (IGF-I) and markedly increased IGF binding protein (IGFBP) plasma levels plays a pathogenic role for growth retardation and catabolism in children with chronic renal failure. To investigate the mechanism of these alterations, experiments were performed in an experimental model of uremia in rats (5/6 nephrectomy) and in pair-fed and ad libitum-fed sham-operated controls Using a specific solution hybridization/RNase protection assay, we observed a marked reduction of hepatic IGF-I messenger RNA (mRNA) abundance at steady state in uremic animals (37 +/- 5% of control) compared both with pair-fed (65 +/- 10%) and ad libitum-fed controls (100 +/- 11%) (P < 0.001). Reduced IGF-I gene expression was clearly organ-specific; it was most pronounced in liver (significant vs., pair-fed controls) and lung and muscle tissue (significant vs., ad libitum-fed controls); no change was observed in kidney and heart tissue. To determine a potential mechanism of reduced hepatic IGF-I gene expression in uremia, the hepatic GH receptor gene expression in the same experimental animals was analyzed by specific solution hybridization/RNase protection assay. Uremic animals had a 20-30% reduction of hepatic GH receptor mRNA abundance compared with controls. Hepatic GHBP expression in uremia was decreased in parallel. Despite the reduction of hepatic IGF-I mRNA abundance, plasma IGF-I levels in uremia were not different from ad libitum-fed controls. This discrepancy is explained by an increased concentration of IGFBPs in uremic plasma. By RIA, plasma IGFBP-1 levels in uremia were increased 4-fold; by Western immunoblot, plasma IGFBP-2 levels were increased 7-fold and plasma IGFBP-4 levels were increased 2-fold compared with both control groups. Intact IGFBP-3 (M(r), approximately 48 kDa) and low molecular IGFBP-3 fragments were not significantly different among the three groups. By Northern blot analysis, hepatic IGFBP-1 mRNA levels in uremia were 2-fold higher than in controls. IGFBP-2 mRNA abundance in liver tissue was increased 4-fold, whereas in kidney there was a significant reduction of IGFBP-2 mRNA (30% of control). IGFBP-4 mRNA was increased by 50% in kidney but not in liver. Plasma insulin and corticosterone levels were not different among the groups. Our study shows that hepatic IGF-I gene expression was specifically reduced in uremia, partially as the consequence of a reduced hepatic GH receptor gene expression. One of the mechanisms contributing to increased IGFBP levels in uremia is increased hepatic gene expression of IGFBP-1 and IGFBP-2. The imbalance between reduced hepatic IGF-I production and increased hepatic IGFBP-1 and 2 production is likely to play a pathogenic role for catabolism and growth failure in CRF.

Growth hormone treatment in growth retarded children with end stage renal failure: effect on free/dissociable IGF-I levels.

Growth retardation in children with endstage renal disease (ESRD) is associated with normal to slightly low concentrations of insulin-like growth factor (IGF)-I and increased concentrations of IGF-binding proteins (IGFBPs) in serum. Consequently, IGF-I bioactivity is reduced in serum from uremic patients presumably due to a decrease in the concentration of free IGF-I. Improvement of linear growth with growth hormone (GH) treatment of uremic children is thought to be due to increased IGF-I/IGFBP ratio, thus resulting in increased free IGF-I levels during treatment. The purpose of the present study was to determine whether free/dissociable IGF-I levels are in fact low in uremic children and whether increased growth velocity during GH treatment is associated with an increase in the free IGF-I concentration. Serum total and free/dissociable IGF-I concentrations were measured in 5 children with ESRD before and during treatment with GH, and in control children matched for age, pubertal status, and body mass index. Height velocity increased from 3.7 +/- 1.0 cm/yr to 6.5 +/- 1.2 cm/yr with an increment in height SDS at the end of the first year of GH treatment. Free/dissociable IGF-I concentrations tended to be lower in uremic children compared to control children (3.0 +/- 0.3 vs 7.3 +/- 2.1 micrograms/l, respectively). During GH treatment, free/dissociable IGF-I levels increased significantly to 8.5 +/- 1.0 micrograms/l at 3 months and 6.9 +/- 1.4 micrograms/l at 6-24 months, p < 0.05 compared to pretreatment. Total IGF-I levels were 243 +/- 18 micrograms/l in children with ESRD before treatment and these values also increased during GH treatment (740 +/- 114 micrograms/l at 3 months and 442 +/- 44 micrograms/l at 6-24 months, p < 0.05, compared to pretreatment). Total IGF-I concentration in the control group was 439 +/- 114 micrograms/l. These results support the hypothesis that growth retardation in children with chronic renal failure is associated with a reduction in the concentration of free, biologically available IGF-I, and that increased growth velocity during GH treatment of these children is associated with restoration of free IGF-I concentrations.

Changes in laminin during recovery from postischemic acute renal failure in rats.

Changes in the immunoreactivity of laminin have been demonstrated in a variety of tissues undergoing injury-regeneration process and during nephrogenesis. Studies in vitro revealed that laminin is important in many cellular functions such as growth, differentiation, and cell communication. This study examined the changes of laminin in the extracellular matrix (ECM) of proximal straight tubules (PST) in the outer stripe of the outer medulla after renal ischemia, an area where most morphological damage occurred. Anesthetized male Sprague-Dawley adult rats underwent a 30-min temporary occlusion of the left renal artery. The inulin clearance (Cin) of the postischemic left kidneys was significantly decreased at 30 min, 1 day, 2 days, and 5 days after the injury, and at 7 and 10 days after the injury it rose to a level not significantly different from the sham-operated controls. Using immunogold electron microscopy, the density of immunoreactive laminin (gold-conjugated laminin grains/micron2 ECM area) in PST where flattened PST cells were present was decreased at 1 day and 2 days, and at 5 days, a time when the renal function was still depressed, it returned to a level not significantly different from that in controls. These changes were not observed in those PST or proximal convoluted tubules in which morphology was intact. Further studies are needed to determine if these changes in laminin of damaged PST cells have any significant role during their recovery from the ischemic injury.

Growth hormone and insulin-like growth factor-I and mesangial matrix in uremic rats.

Combined growth hormone (GH) and insulin-like growth factor-I (IGF-I) therapy has been advocated for clinical use to minimize the diabetogenic effect of GH and enhance their anabolic effects. However, GH has been shown to accelerate the development of glomerular sclerosis in experimental animals and IGF-I mediates the renal effects of GH. The purpose of this study was therefore to examine morphometrically the effects of GH (1 mg intraperitoneally three times a week), IGF-I (50 micrograms/kg body weight subcutaneously twice a day), and combined GH/IGF-I treatments in vivo on mesangial matrix at 3-20 days after 5/6 nephrectomy in 140- to 150-g rats. There were no significant changes in growth and renal function after GH and/or IGF-I treatment. The effects of GH and IGF-I on glomerular size were additive, which were more prominent in juxtamedullary glomeruli. GH induced proportional increases in mesangial area (MA) and glomerular area (GA), whereas IGF-I induced a similar increase in GA without a corresponding change in MA. When compared with GH treatment alone, combined GH/ IGF-I treatment resulted in a lesser degree of mesangial expansion despite an enhanced glomerular size. While additional studies are needed to examine the long-term effects of these findings, our results suggest a potentially beneficial effect of combined GH/IGF-I therapy during uremia.

Posterior urethral valves in patients with Down syndrome.

Renal and urological anomalies in Down syndrome (DS) have received little attention compared with the nephrourological findings described in other chromosomal abnormalities. Renal hypoplasia, hydroureteronephrosis, ureterovesical and ureteropelvic junction obstruction, and vesicoureteral reflux, but not posterior urethral valves, have been associated with DS. We report the occurrence of posterior urethral valves in three male infants with DS at a single institution. All had multiple urological procedures for correction or palliation of obstruction. Children with DS may have an increased risk for developing posterior urethral valves and obstructive uropathy. Furthermore, they may also develop chronic renal failure secondary to posterior urethral valves. Therefore, we suggests that infants with DS be screened with ultrasonography for renal and urological abnormalities early in life and, if abnormal, a contrast voiding cystourethrogram be performed to rule out posterior urethral valves or other bladder or urethral abnormalities. A review of the renal and urological anomalies in DS reported in the literature since 1960 is presented.

Accumulation of acidic renin isoforms in kidneys of cyclosporine-A-treated rats.

Chronic cyclosporin A (CsA) treatment results in major hemodynamic changes in the renal microvasculature and in expression of the intrarenal renin angiotensin system. Changes in renin expression in kidneys of CsA-treated rats include the recruitment of immunoreactive renin in afferent arterioles and in the juxtaglomerular apparatus. This study presents evidence that an acidic isoform of renin is increased in kidneys of CsA-treated rats. Immunoblots of rat kidney homogenate separated by polyacrylamide-gel electrophoresis and also by isoelectric focusing demonstrate the presence of an acidic isoform (pl 5.5 and estimated molecular weight of approximately 32 to 36 kd) seen in increased amounts in kidney homogenate from CsA-treated rats. Silver-stained two-dimensional gels of renin separated from kidney homogenate with pepstatin agarose confirm the presence of an acidic renin isoform in CsA-treated rats. In rats that received CsA for varied intervals of 1, 3, 5, and 8 wk, this acidic isoform is shown to significantly accumulate relative to duration of treatment with CsA when immunoreactive bands are analyzed by densitometric scanning (r2 = 0.90, P < 0.001). Renin enzymatic activity also increased in kidney homogenate of CsA-treated rats relative to duration of treatment with CsA (r2 = 0.486, P < 0.001). Prorenin in these same samples was significantly decreased compared with controls. The acidic renin isoform identified in kidney homogenate of CsA-treated rats may be involved in the vascular changes that are seen in this model.

Megacystis-microcolon-intestinal hypoperistalsis syndrome.

The megacystis-microcolon-intestinal hypoperistalsis syndrome is a congenital disorder characterized by urinary bladder distension and hypoperistalsis throughout the entire gastrointestinal tract. We present a new case with the typical clinical, radiological, and pathological findings of the syndrome. The diagnosis should be suspected in a patient who present clinically with intestinal obstruction and urinary retention, and confirmed with imaging studies, including abdominal plain films, urinary tract ultrasonography, and contrast studies of the colon and the bladder. The prognosis is generally very poor. Our patient died secondary to sepsis on day 5 of life.

Insulin-like growth factor-1 enhances epidermal growth factor receptor activation and renal tubular cell regeneration in postischemic acute renal failure.

Growth factors such as insulin-like growth factor-1 (IGF-1), epidermal growth factor (EGF), and hepatocyte growth factor have been shown to accelerate the recovery from postischemic acute renal failure (ARF) with a concomitant increase in DNA synthesis. Interactions between growth factors have been demonstrated in a number of in vitro studies. This study examined the effect of exogenous IGF-1 on the DNA synthesis and EGF receptor (EGF-R) activation in postischemic rat kidneys. Thirty minutes after the relief of 30-minute total occlusion of the left renal artery in anesthetized 225 to 300 gm Sprague-Dawley rats, either IGF-1 (75 micrograms/kg) or normal saline solution (NS, 0.2 ml) was given by intravenous bolus, followed by twice daily subcutaneous injections of IGF-1 (50 micrograms/kg) or 0.2 ml NS for 4 days, respectively, in IGF-1-Tx) and NS treated (NS-Tx) groups (n = 8 each). On the day after the completion of treatment, inulin clearance (ml/kg/min) of the postischemic kidneys in the IGF-1-Tx group was significantly higher (p < 0.01) than inulin clearance of kidneys in the NS-Tx group. This was associated with improved kidney morphology. IGF-1 treatment also enhanced the labeling index of 5-bromo-2'-deoxyuridine (percent of stained tubule cells), a marker for active DNA synthesis, in the outer medulla of postischemic kidneys at 1 day and 2 days after the injury. EGF-R tyrosine phosphorylation (which reflects receptor activation) increased in postischemic kidneys in both NS-Tx (n = 5) and IGF-1-Tx (n = 3) groups 1 day after the injury as compared with nonischemic contralateral kidneys. In the IGF-1-Tx group there was also increased iodine 125-labeled EGF binding and EGF-R protein. Our results demonstrate a beneficial effect of IGF-1 on postischemic ARF. Furthermore, they suggest that EGF-R activation is involved in tubular regeneration and that IGF-1 may enhance EGF-R activation by increasing EGF-R expression.

Recurrence of immunoglobulin A-kappa crystalline deposition disease after kidney transplantation.

Cases of immunoglobulin A heavy chain and kappa light chain deposition disease are rare and their clinical presentations vary. We report one patient with histopathologic and clinical findings of a microangiopathic glomerulonephritis due to immunoglobulin A-kappa deposition. Ultrastructural studies revealed highly ordered deposits in the capillary lumen, mesangium, and basement membrane. The disease recurred at 2.5 years after a cadaveric kidney transplantation. Pulse steroid therapy was repeatedly effective in retarding further progression of renal deterioration in this patient.

Dopamine-1 receptors in the proximal convoluted tubule of Dahl rats: defective coupling to adenylate cyclase.

We have previously reported a defect in the coupling of the renal dopamine-1 receptor (D1) to adenylate cyclase (AC) in the proximal convoluted tubule (PCT) of the spontaneously hypertensive rat (Okamoto-Aoki strain). To determine if this defect is present in another model of hypertension, we microdissected PCTs from Dahl salt-sensitive (DSS) and Dahl salt-resistant (DSR) rats on low- or high-NaCl diet. The ability of two selective D1 agonists, fenoldopam and SND-919-C12, and forskolin to stimulate AC activity in PCT was determined in each of the four groups of rats. Fenoldopam (10(-7) M) and SND-919-C12 (10(-6) M) failed to stimulate AC activity in the PCT of DSS rats whether on a low- or high-NaCl diet. In DSR rats, however, both fenoldopam and SND-919-C12 stimulated AC activity by 289-320% and 220-270%, respectively, whether on a low- or high-NaCl intake. Forskolin (10(-5) M), which directly stimulates AC activity, increased AC activity in all four groups. These studies show that in DSS rats the D1 receptor in the PCT fails to respond to D1 agonists. This defect is not a consequence of the hypertension because it was present in the DSS rats on a low-salt diet and before blood pressure elevation.

Direct visualization of renin-cell distribution in preglomerular vascular trees dissected from rat kidney.

Three methods to visualize directly the distribution of granulated renin-positive cells in vascular trees microdissected from rat kidney were developed. Kidneys were removed from anesthesized rats, hemisectioned, macerated in HCl, and soaked in distilled water for 24-48 h. Cortical preglomerular vascular trees consisting of arcuate and cortical radial arteries and afferent arterioles were microdissected with the aid of a stereomicroscope. Granulated cells can be visualized in three ways. First, under transmitted or incident light observation, granulated cells are readily distinguished from the surrounding smooth muscle cells, because of marked differences in the refractive properties of these two cell types. Second, quinacrine, a fluorescent, intravital stain selective for dense-core granules, can be administered (2 mg/kg iv) to the rat 1 h before nephrectomy. When illuminated with 440-nm light, granulated cells fluorescence strongly at 510 nm. Third, specific immunostaining for renin can be obtained with a polyclonal anti-rat renin antibody and avidin-biotin immunoperoxidase staining in vascular trees subjected to cell permeabilization with Triton. These new techniques permit the direct visualization of the distribution of granulated renin-positive cells in preglomerular vessels under conditions in which the vascular architecture is largely preserved.

IgG and IgA classes of anti-neutrophil cytoplasmic autoantibodies in a 13-year-old girl with recurrent Henoch-Schonlein purpura.

We describe a 13-year-old girl with recurrent Henoch-Schonlein purpura whose symptoms were precipitated by upper respiratory tract infections. Her serum was positive for both IgG and IgA classes of anti-neutrophil cytoplasmic autoantibodies by immunofluorescence. The titers of both autoantibodies correlated with disease activity. The immunopathology underlying these findings is discussed.