Adrenomedullin and nitrite levels in children with Bartter syndrome

Children with Bartter syndrome have lower than normal vascular reactivity with normotension in spite of biochemical and hormonal abnormalities which are typical of hypertension. Nitric oxide (NO) is a potent endogenous vasodilator, and plays an important role in the control of vascular tone. Adrenomedullin (AM) is a novel hypotensive peptide originally isolated from human pheochromocytoma. The possible role of NO and AM in maintaining this reduced vascular reactivity was examined by studying plasma and urinary nitrite, a stable metabolite of NO, and AM levels in ten children with Bartter syndrome, ten healthy controls, and five children with hypokalemia of causes other than Bartter syndrome (pseudo-Bartter). Urinary excretion of nitrite (μmol/mg urinary creatinine) was 8.9.±1.2 in children with Bartter syndrome, 4.7.±0.9 in healthy controls, and 2.9.±0.8 in pseudo-Bartter (P<0.05). Plasma nitrite levels (μmol/l) were 101.9±23.4, 59.9±14.7, and 65.0±29.7, respectively (P>0.05), in the three groups. Urinary excretion of AM (pmol/mg urinary creatinine) was 187±40, 65±10, and 160±50, respectively (P<0.05), in the three groups. Plasma AM levels were 47.4±1.8, 39.9±5.9, and 42.4±3.9, respectively (P>0.05), in the three groups. The same parameters were repeated in the two groups of controls and in the Bartter patients in the 6th month of therapy. Urinary nitrite and AM levels were still higher in the Bartter patients than in the other groups. We conclude that in Bartter syndrome the increased NO production may be responsible for the reduced vascular response of the disease. Initially, increased levels of AM in Bartter syndrome and pseudo-Bartter may be a compensatory response to acute hypokalemia; however, continuation of a high level of urinary excretion of AM in children with Bartter syndrome may suggest also the possible role of AM in the reduced vascular response of the disease. Received: 2 December 1999 / Revised: 24 July 2000 / Accepted: 27 July 2000     

Urotensin-II levels in children with minimal change nephrotic syndrome

Human urotensin-II (hU-II) is the most potent mammalian vasoconstrictor identified to date. Although it is expressed mainly in the brain and spinal cord, it is also detected in other tissues, such as the kidney. It has been speculated that U-II might be an important physiological mediator of vascular tone and blood pressure in humans. To our knowledge, no studies have investigated the level of U-II in children with minimal change nephrotic syndrome (MCNS). Considering the renal synthesis and vasoactive role of U-II, we aimed to measure the plasma and urinary levels of U-II in children with MCNS, and investigate the correlation with other clinical and laboratory findings. Twenty-six children with clinical MCNS, ranging in age from 2 to 7 years, were compared with 16 healthy age- and sex-matched controls. The median age of the children was 4.73±2.36 years. U-II level was measured by RIA. Plasma U-II concentrations (pg/ml) were decreased during relapse (20.11±14.43 in relapse, 38.94±23.86 in remission, P <0.05), whereas urinary U-II levels (pg/mg urinary creatinine) were significantly higher in relapse than in remission (37.31±28.43 in relapse, 31.09±21.10 in remission, P <0.05). We could not detect any relationship between U-II levels and other clinical and laboratory parameters. Our data indicate that the important changes in plasma and urinary U-II levels during relapse may be the result of heavy proteinuria rather than playing a role in mediating the clinical and laboratory manifestations of MCNS in children.     

Adrenomedullin and total nitrite levels in children with Henoch-Schönlein purpura

Nitric oxide (NO) is synthesized from endothelium and has an important role in the control of vascular tonus. Adrenomedullin (AM) is a potent vasodilator, and cytoprotective peptide is produced not only in adrenal medulla, but also in the vascular smooth muscle and endothelial cells. To investigate the endothelial synthesis of AM and NO, and endothelial injury in Henoch-Schönlein purpura (HSP), we measured their levels in 16 children with HSP, who were evaluated during the acute and remission phases, and compared with 12 healthy controls. Plasma AM levels (pmol/ml) were significantly higher in acute phase children (46.87±11.49) than in those in remission (35.59±12.39, p<0.01) and controls (30.70±9.12, p<0.001). Similarly, plasma total nitrite levels (mol/l) were higher in acute phase patients (47.50±12.30) than in those in remission (35.94±10.08, p<0.005) and controls (34.56±11.51, p<0.05). Urinary excretion of AM (pmol/mg creatinine) was higher in acute phase patients (53.85±23.22) than in remission patients (29.97±9.33, p<0.01) and controls (37.43±15.78, p<0.05). Patients had increased urinary nitrite excretion (mol/mg creatinine) in acute phase (2.39±1.18) compared to those in remission (1.53±0.90, p<0.05) and controls (1.05±0.61, p<0.005). There was no significant difference between remission phase and controls in AM and nitrite levels (p>0.05). This study concluded that AM and NO may have a role in the immunoinflammatory process of HSP, especially in the active stage, although whether this perpetuates, or protects against, further vascular injury is not clear. Further studies are needed to clearly establish the roles of AM and NO in the pathogenesis of HSP.     

Urinary histamine excretion in proteinuric states

The kidney possesses the enzymatic steps required for the biosynthesis of histamine and this autocoid may play a role in modulating renal hemodynamics and the local inflammatory response to immunologic injury. We, therefore, measured urinary histamine. N-methylhistamine and N-methylimidazole acetic acid concentrations in patients with proteinuria due to a variety of disease states-idiopathic nephrotic syndrome (n = 19), systemic lupus erythematosus (n = 10), refractory focal segmental glomerulosclerosis (n = 10) and control patients (n = 16). Urinary histamine concentration was significantly reduced in treatment-responsive idiopathic nephrotic syndrome during disease relapse compared to remission (16.6 +/- 3.6 vs. 28.4 +/- 4.8 mumol/mol creatinine, p less than 0.02). The levels were also depressed in children with other causes of persistent proteinuria, including systemic lupus erythematosus (10.3 +/- 4.0 mumol/mol creatinine) and focal segmental glomerulosclerosis (14.6 +/- 2.8 mumol/mol creatinine) compared to normal controls (31.4 +/- 4.7 mumol/mol creatinine). The decreased urinary excretion of histamine and its metabolites in patients with proteinuria may be a result of immunologically mediated mesangial cell injury or represent a compensatory hemodynamic response to limit urinary protein losses.     

Adrenomedullin and nitric oxide in children with detrusor instability

Detrusor instability (DI) and detrusor-external sphincter dyssynergia lead to poor bladder emptying and high bladder pressure. Recent results indicate that nitric oxide (NO) is an important transmitter or messenger molecule in autonomic neurotransmission. Adrenomedullin (AM) is a potent vasodilator and natriuretic peptide, originally purified from human pheochromocytoma. Since NO and AM have vasodilatory effects on smooth muscles, we considered them to be of interest in children with DI. We determined the tissue levels of NO and AM in 14 children with DI, and compared these with 6 children with normal bladder activity. Bladder biopsy total nitrite levels (nmol/g tissue) were decreased in children with DI (10.69+/-0.91 vs. 12.83+/-0.98, P<0.01). However, AM levels (pmol/g tissue) were increased in the same patients (48.84+/-3.52 vs. 28.79+/-1.53, P<0.001). According to our results, decreased NO production probably has a role in the pathophysiology of DI, although increased AM appears to be compensatory. NO may provide a therapeutic target in clinical situations related to DI. However, the functional significance of AM and NO in bladder smooth muscle remains to be determined by further detailed studies.     

Heparanase activity is dysregulated in children with steroid-sensitive nephrotic syndrome

BACKGROUND: Immune cells express heparanase, an endoglycosidase, able to degrade heparan sulfate glycosaminoglycan (HSGAG) in the glomerular capillary wall (GCW) and potentially induce proteinuria. The aim of this study was to determine whether dysregulated heparanase expression is associated with the heavy proteinuria of childhood steroid-sensitive nephrotic syndrome (SSNS). METHODS: Plasma and urinary heparanase activity and peripheral blood mononuclear cell (PBMC) mRNA heparanase levels [real-time polymerase chain reaction (PCR)] were measured in children with SSNS in relapse and remission. Plasma and urinary heparanase activity was determined in adult patients with nephrotic syndrome and in age- and gender-matched controls. RESULTS: Plasma heparanase activity was reduced in SSNS with relapse (811.2 units) compared to remission (1147.96 units) (P= 0.003) and control subjects (1390.51 units) (P < 0.001). In adult nephrotic syndrome, plasma heparanase activity was significantly lower in patients compared to controls. However, there was no difference between remission and relapse states. In children, urinary heparanase activity/urinary creatinine ratio was highest in SSNS relapse (14.26 units/mg) compared with remission (7.43 units/mg) (P= 0.016) and controls (2.29) (P < 0.001). However, PBMC heparanase mRNA expression was not different between these three groups. In adult nephrotic syndrome, urinary heparanase activity/urinary creatinine levels were lower in both remission and relapse compared to controls and there was no difference between remission and relapse states. CONCLUSION: In childhood SSNS, there is a qualitative and quantitative difference in urinary heparanase activity expression that is not paralleled in adult nephrotic syndrome. These data suggest that dysregulated heparanase expression may play a significant role in the pathogenesis of SSNS, possibly through an abnormality in post-translational control of latent heparanase activation.     

Increased urinary nitrite excretion in primary enuresis: effects of indomethacin treatment on urinary and serum osmolality and electrolytes,urinary volumes and nitrite excretion

OBJECTIVE: To assess urinary nitrite excretion, a stable end product of nitric oxide (NO), in patients with enuresis and in normal controls, and to evaluate the effects of indomethacin (a potent prostaglandin synthesis inhibitor) on urinary nitrite excretion, other urinary variables and bladder capacity. PATIENTS AND METHODS: The study comprised 10 patients with primary enuresis and 10 normal comparable controls (age range 6-14 years). Nitrite was assayed in 'spot' morning urine samples in both the enuretics and normal controls. Enuretics were then given 50 mg indomethacin suppositories each night; urine volume, urinary osmolality and electrolytes, serum osmolality and electrolytes and urinary nitrite were assayed before indomethacin treatment and after 15 days of treatment. RESULTS: The mean (sd) urinary nitrite excretion was 24.4 (19.6) micromol/L in normal children and 275.9 (111.2) micromol/L in enuretics (P<0.05). With indomethacin, the urinary nitrite concentration was significantly decreased to 141 (45.1) micromol/L (P<0.05) and associated with a significant reduction in bed-wetting episodes and voiding frequency. The functional bladder capacity was <70% of the predicted value for age in six of the patients; they had significant improvements on indomethacin, to values similar to those in patients with a nearly normal functional bladder capacity. Indomethacin decreased the 24-h urinary volume by 41%, the night volume by 40%, clearance of free water by 46% and increased the day : night urinary volume ratio by 55%. The absolute amounts of urinary calcium, magnesium, phosphorus, urea, creatinine, and glucose were lower on indomethacin, although not statistically significantly so. Indomethacin decreased the 24-h urinary and 'spot' morning osmolality and osmotic clearance. There were no significant changes in serum osmolality and electrolyte concentrations. Indomethacin also decreased the absolute amount of urinary sodium, chloride and potassium, fractional sodium and potassium excretion, and filtered sodium. Creatinine clearance was decreased by 20% (P>0.05) and normal 24-h urinary protein was significantly lower, by 47%, after indomethacin treatment (P<0.05). CONCLUSION: Urinary nitrite excretion increased significantly in patients with primary nocturnal enuresis; indomethacin markedly reduced bed-wetting episodes and decreased the frequency of voiding in enuretics with small or normal functional bladder capacity, which was associated with a significant decrease in urinary nitrite excretion. Indomethacin reduced bed-wetting by decreasing the urine volume, clearance of free water and urinary electrolytes, and through possible effects on bladder and urethral contraction, by inhibiting NO and prostaglandin synthesis. NO and prostaglandins might be important in the pathogenesis of primary enuresis.     

T-cell subsets,interleukin-2 receptor expression and production of interleukin-2 in minimal change nephrotic syndrome

This study was designed to investigate T-lymphocyte subsets interleukin-2 receptor (IL-2R) expression and IL-2 production in minimal change nephrotic syndrome (MCNS). Peripheral blood T-lymphocytes and IL-2R expression were analysed using fluorescein isothiocyanatelabelled CD3, CD4, CD8 and CD25 monoclonal antibodies with flow cytometry. IL-2 production was determined by enzyme immunoassay. Ten children with MCNS in relapse and in remission were evaluated. Thirteen healthy children served as controls. The patients in relapse demonstrated a moderate decrease in the total absolute lymphocyte counts and CD8(+) T-lymphocytes compared with controls (P<0.05) and had a greatly increased IL-2R expression in frashly isolated, unstimulated peripheral lymphocytes compared with patients in remission and controls. While this was not statistically significant, IL-2R expression on cultured lymphocytes stimulated with phytohaemagglutinin was significantly elevated in relapse compared with those in remission and controls (P<0.05). IL-2 production did not correlate well with IL-2R expression and there was no significant difference between the groups. Our results suggest that T-cell subset changes and high IL-2R expression on peripheral lymphocytes may indicate the presence of stimulated T-cell populations in MCNS which could contribute to the immunopathogenesis.     

Sodium-lithium countertransport in children with nephrotic syndrome

The mechanisms of sodium retention in edema-forming minimal change nephrotic syndrome (MCNS) have not been completely evaluated. The aim of this study was to characterize the transmembrane sodium transport in nephrotic syndrome by measuring the erythrocyte sodium-lithium countertransport (SLC) in vitro. Eighteen children with MCNS were studied in the edema-forming state, and subsequently at the beginning of remission. Nephrotic children with edema retained sodium (10±12 μmol/day) and had a higher SLC [426±118 vs. 281±60 μmol/l red blood cells (RBC) per hour, P=0.003). The intracellular sodium concentration of nephrotics was 6.1±2.1 mmol/l RBC, which did not differ from that of controls (6.42±2.24, n=13). In remission sodium balance became negative (–30 ±21 mmol/day), and the SLC decreased but still differed significantly from control values (P=0.009). The intracellular sodium content decreased to 4.4±0.9 mmol/l RBC (P=0.002). There was a negative correlation between erythrocyte SLC and plasma albumin concentration (r=0.48, P=0.003), and urinary sodium excretion rate (r=0.66, P=0.001). In conclusion, erythrocyte SLC is high in the edema-forming state of childhood nephrotic syndrome and decreases with the onset of remission. A role for the SLC in the altered sodium homeostasis of nephrotic syndrome is suggested. Received: 6 April 1998 / Revised: 5 October 1998 / Accepted: 4 November 1998     

Diagnostic value of urinary retinol-binding protein in childhood nephrotic syndrome

Urinary excretion of N-acetyl-β-d-glucosaminidase (NAG) and retinol-binding protein (RBP), sensitive markers of renal tubular damage and dysfunction respectively, were evaluated in paired remission and relapse urine samples from 16 patients (median age 12 years), with minimal change nephrotic syndrome (MCNS), in single samples from 5 nephrotic patients (median age 12 years) with focal segmental glomerulosclerosis (FSGS) and in 183 normal controls aged 2–16 years. The NAG and RBP data were expressed as a ratio over urinary creatinine (Cr). The NAG/Cr and RBP/Cr geometric means (ranges) for normal subjects were 11.1 (3.4–35.5) μmol 2-methoxy-4-(2"-nitrovinyl)-phenol (MNP)/h per mmol and 3.1 (0.3–38.8) μg/mmol, respectively. The NAG/Cr data revealed a weak negative correlation with age in normal children, whereas RBP/Cr was independent of age. RBP/Cr and NAG/Cr in MCNS in remission were the same as in controls. In MCNS in relapse, NAG/Cr was significantly elevated (P=<0.001), while in FSGS both RBP/Cr and NAG/Cr were significantly raised (P=<0.001 and P<0.008, respectively). These findings suggest that elevated NAG/Cr may be an indicator of relapse in both MCNS and FSGS and elevated RBP/Cr may allow differentiation between the two. Received May 7, 1997; received in revised form January 30, 1998; accepted February 4, 1998     

Long-term follow-up after cyclophosphamide and cyclosporine-A therapy in steroid-dependent and -resistant nephrotic syndrome

A retrospective study was made on 37 children with idiopathic nephrotic syndrome (INS). At the beginning, all patients were steroid sensitive but received more than one steroid course (median 4). Following several relapses, they became steroid dependent or steroid resistant. Group 1 consisted of 22 children [3 focal segmental glomerulosclerosis (FSGS), 19 minimal-change NS (MCNS)] who received cyclophosphamide (CP) orally for 2.5 +/- 0.5 months. Group 2 consisted of 15 children (7 FSGS, 8 MCNS) who received cyclosporine-A (CSA) for 28 +/- 15 months. The level of proteinuria decreased significantly and remained low during the follow-up. The relapse-free period was significantly longer in the CP group (CP 30 +/- 21.5; CSA 26.2 +/- 18 months, p < 0.001). The relapse rate decreased significantly in both groups and remained in this lower level during the follow-up (from 3.4 +/- 2.8 to 0.1 +/- 0.2/year in group 1, and from 3.7 +/- 3.1 to 0.6 +/- 0.8/year in group 2). At the end of the 5-year follow-up, 20/22 patients (90.9%) and 10/15 patients (66.6%) were in remission in groups 1 and 2 respectively, with or without treatment (p < 0.05). In the long term, both CP and CSA is effective second-line therapy following steroid monotherapy in INS patients, but the relapse rate was lower and the relapse free period was significantly longer in the CP-treated group.     

Plasma and urinary adrenomedullin levels in children with acute pyelonephritis

AIM: Adrenomedullin (AM), a novel peptide recently isolated from pheochromocytoma, eliciting vasorelaxing activity, is the strongest among all known peptides. AM has been detected in the adrenal medulla, cardiac tissue, lung and kidney. Immunohistochemical studies have demonstrated the localization of AM in glomeruli, tubules and collecting cells of the kidney. Clinically, plasma and urinary AM levels are altered in patients with different renal disease. The present study aims to determine plasma and urinary AM levels in children with acute pyelonephritis (APN) and compare the results with a control group. MATERIALS AND METHODS: The study group was comprised of 19 patients with APN aged 11.6 +/- 3.7 months (range, 6-18 months) and the control group consisted of 16 cases aged 11.5 +/- 3.2 months (range, 7-16 months). Acute pyelonephritis was diagnosed by clinical, laboratory and imaging methods. Plasma and urinary AM levels were measured by high performance liquid chromotography (HPLC). RESULTS: The plasma AM levels were lower in APN patients (33.40 +/- 2.27 pmol/mL) than in the control group (43.76 +/- 4.27 pmol/mL) (P < 0.001), whereas the urinary AM levels were higher in APN patients (248.58 +/- 140.63 pmol/mg urinary creatinine) than in the control group (49.42 +/- 45.23 pmol/mg) (P < 0.001). Coefficients of correlation between urinary AM levels and C-reactive protein and white blood cells were statistically significant (r = 0.472, P = 0.041; r = 0.555, P = 0.014, respectively). CONCLUSION: Adrenomedullin, a smooth muscle relaxant peptide that is synthesized in urinary tract tissue might have a role in acute pyelonephritis. However, the importance of AM in the pathogenesis of acute pyelonephritis remains to be determined by further detailed studies.     

Analysis of nitric oxide in the exhaled air of patients with chronic glomerulonephritis.

BACKGROUND: Nitric oxide (NO) plays an important role in renal hemodynamics and function. Although production of NO in the glomeruli has been found to be increased in animal models of glomerulonephritis, it remains unclear whether its endogenous production is enhanced in patients with chronic glomerulonephritis (CGN). SUBJECTS AND METHODS: We measured NO output in exhaled air as an indicator of its local production in the lungs and plasma and urinary nitrite plus nitrate (NO2-/NO3-) levels as indicators of its production in the whole body in 21 patients with CGN in 31 healthy controls. RESULTS: The patients exhaled higher concentrations of NO (29.5 +/- 1.4 vs. 18.7 +/- 1.0 parts per billion (ppb), mean +/- SEM, p < 0.0001) and exhaled NO output was also higher than in controls (166.6 +/- 6.8 vs. 95.5 +/- 5.6 nl/min/m2, p < 0.0001). Plasma NO2-/NO3- concentrations were also significantly greater in the patients than in the controls (81.6 +/- 7.2 vs. 41.1 +/- 4.3 micromol/l, p < 0.001). In patients with CGN, exhaled NO output correlated negatively with creatinine clearance (r = -0.62, p < 0.05). Oral administration of prednisolone (60 mg/day) for two weeks did not significantly affect the exhaled NO output in the patients (160 +/- 7 vs. 200 +/- 30 nl/min/m2, p = NS) despite a decrease in urinary protein excretion (12.0 +/- 2.9 vs. 1.4 +/- 0.6 g/day, p < 0.01). CONCLUSION: These findings suggested that endogenous NO production is increased in patients with CGN. Increased endogenous NO production may play some pathophysiological role in these patients.     

Supplementation with a low dose of L-arginine reduces blood pressure and endothelin-1 production in hypertensive uraemic rats.

BACKGROUND: We documented recently that increased endothelin-1 (ET-1) production in blood vessels and glomeruli of uraemic rats plays a crucial role in the development of hypertension and the progression of chronic renal failure. Normally, biological effects and local production of ET-1 are attenuated by the immediate release of nitric oxide (NO). Increasing evidence suggest, however, that NO release is impaired in chronic renal failure. We investigated whether supplementation with L-arginine, the natural precursor of NO, improves NO synthesis in uraemic rats with reduced renal mass and modulates vascular and renal ET-1 production as well as blood pressure and renal failure progression. METHODS: One week after surgical renal mass reduction, the uraemic and sham-operated animals received either no treatment or 0.1% L-arginine in drinking water for 5 weeks. In another series of experiments, uraemic rats received 1% L-arginine for 5 weeks. Immunoreactive-ET-1 (ir-ET-1) levels in plasma, urine, and vascular and renal tissue preparations was measured by radioimmunoassay after sample extraction and purification. RESULTS: Before treatment, systolic blood pressure was significantly elevated in uraemic animals compared to sham-operated controls (156+/-7 vs 111+/-3 mmHg, respectively; P<0.01). Thereafter, systolic blood pressure increased further in uraemic-untreated rats (systolic blood pressure at week 5; 199+/-9 mmHg, P<0.01), whereas it remained similar in uraemic rats supplemented with 0.1% L-arginine (171+/-9 mmHg, NS). At the end of the study, serum creatinine and urea, proteinuria and ir-ET-1 excretion were significantly augmented, while creatinine clearance was reduced in uraemic animals compared to the controls. Ir-ET-1 level was also increased in glomeruli as well as in thoracic aorta, mesenteric arterial bed, and pre-glomerular arteries, and was associated with vascular hypertrophy as assessed by tissue weight. In contrast, ir-ET-1 level was diminished in the renal papilla of uraemic rats. Treatment with 0.1% L-arginine significantly reduced proteinuria and urinary ir-ET-1 excretion (P<0.05) as well as ir-ET-1 level in glomeruli (P<0.01) and in thoracic aorta (P<0.05). These changes were associated with increased plasma NO metabolites NO2/NO3 levels in L-arginine-treated animals (P<0.01) and reduced aortic hypertrophy (P<0.05). In contrast, supplementation with 1% L-arginine had no effect on systolic blood pressure in uraemic rats, but exacerbated proteinuria and urinary ir-ET-1 excretion and increased serum urea (P<0.05) were observed. CONCLUSIONS: These results indicate that improvement of NO release with a low dose but not with a high dose of L-arginine significantly attenuates the development of hypertension and the progression of renal insufficiency in rats with reduced renal mass. These protective effects may be mediated in part by the reduction of vascular and renal ET-1 production.     

Adrenomedullin and nitrite levels in children with primary nocturnal enuresis

Primary nocturnal enuresis (PNE) is the most common type of nocturnal enuresis in children, but its etiology remains unclear. Recent studies indicated the differences in urinary electrolytes in enuretic children, and stressed the existence of a renal tubular maturation defect. In this study, 30 children (aged 6-12 years) with PNE were investigated in comparison with 18 healthy controls. We evaluated plasma antidiuretic hormone, electrolytes, 24-h urine volume, osmolarity, and urinary electrolytes. Unlike other studies, we firstly assessed the plasma and urinary adrenomedullin (AM) and total nitrite levels, a stable product of nitric oxide (NO), and investigated their relationship with urinary electrolytes. The plasma AM and total nitrite levels were significantly lower than controls. Urine volume (24-h) and potassium excretion were higher than in controls. However, 24-h urinary osmolarity and excretion of AM were significantly lower than in controls. Our results indicate that there may be a problem in renal regulation of potassium in children with PNE. Although decreased levels of AM and total nitrite may be a compensatory response to abnormal potassium and water excretion, further investigations are required to exclude whether the renal synthesis of AM and NO are also deficient in these children.     

Long-term clinical and pathological effects of cyclosporin in children with nephrosis

The clinical course of eight children with minimal change disease (MCNS) who were treated with cyclosporin (CYA) was retrospectively reviewed (group A). Five children had frequently relapsing (FRNS) and three had steroid-resistant (SRNS) primary nephrotic syndrome (PNS). The mean age (+/-SEM) of the patients at the time of initiation of CYA therapy was 8.01+/-1.30 years. Twelve follow-up renal biopsies, obtained from patients in group A, were compared with baseline 3.36+/-0.76 years after the initiation of CYA. Follow-up renal biopsies from group A were compared with another cohort of eight children with PNS who did not receive CYA (group B, controls). In this later group four children had FRNS and four had SRNS, and all had MCNS on the initial renal biopsy. In group B, the time between the initiation of CYA and the last renal biopsy was 4.07+/-0.82 years. All 36 baseline and follow-up renal biopsies, from group A and B, were retrospectively reviewed by the same pathologist who was blinded to the clinical course and therapy. CYA decreased the number of relapses in patients from group A from 5.20+/-1.02 to 1.14+/-0.63 episodes per year (P<0.05). All patients with SRNS went into remission after initiation of CYA. Estimated creatinine clearance before CYA therapy was unchanged at the end of the observation period, 133+/-10 vs. 131+/-8 ml/min per 1.73m2, respectively. One child developed reversible acute renal failure while on CYA therapy. Attempts to wean three patients off CYA after 3.89+/-0.87 years of CYA therapy were unsuccessful. Mild but increasing tubular atrophy and interstitial fibrosis was observed in serial biopsies of 75% of the patients in group A compared with 25% of the patients in group B, all of whom had MCNS on initial biopsy. In addition, the percentage of renal cortex showing interstitial fibrosis and tubular atrophy in biopsies from group A patients was slightly greater than that of the group B patients (P<0.05). Hence, CYA therapy in children with MCNS is associated with mild renal interstitial fibrosis and tubular atrophy similar to that noted in a minority of the patients with primary MCNS who were not treated with CYA. However, the mild chronic interstitial damage is more frequent and extensive in MCNS patients treated with CYA, suggesting drug-related interstitial alteration. Despite its efficacy and minimal nephrotoxicity in most patients with MCNS, CYA therapy carries the potential for significant morbidity.     

Shear stress-induced platelet aggregation in children with minimal change nephrotic syndrome

Analysis of the hemostasis system using biochemical techniques in children with minimal change nephrotic syndrome (MCNS) has previously been restricted to in vitro assays. The recent introduction of measurement of shear stress-induced platelet aggregation (SIPA) using platelet-rich plasma (PRP) has facilitated detailed investigation of the hemostatic system in vivo. In order to further analyze the etiology of the thrombotic tendency exhibited by patients with childhood MCNS, we investigated SIPA at both low shear stress (L-SIPA) and high shear stress (H-SIPA) in 14 children with MCNS using PRP collected weekly after commencing prednisolone therapy. Seven patients were newly diagnosed cases of MCNS (ND) whereas the remainder had suffered a disease relapse (DR). Prior to prednisolone therapy L-SIPA, which was thought to be affected by fibrinogen (Fbg) levels, was significantly increased in both patient groups compared to normal controls (17.4 +/- 4.1% vs. 3.6 +/- 0.7%, ND vs control, p < 0.01: 11.7 +/- 3% vs. 2 +/- 0.7%, DR vs control, p < 0.01) with values declining at weekly intervals thereafter. Plasma Fbg levels in simultaneously collected samples followed a similar course. In contrast, H-SIPA, which was thought to be affected by von Willebrand factor (VWF), was significantly enhanced in MCNS patients after 1 week of prednisolone therapy compared to the controls (45 +/- 5.1% vs. 26.3 +/- 3.5%, ND vs normal, p < 0.05: 36.9 +/- 3.3% vs. 25.5 +/- 1.6%, DR vs. normal, p < 0.05). Plasma ristocetin cofactor and VWF antigen levels in simultaneously collected samples followed a similar course, whereas thrombin-antithrombin complex (TAT) levels remained constant. These results indicate that SIPA is enhanced in the acute stage of childhood MCNS, especially L-SIPA prior to the initiation of prednisolone therapy and H-SIPA after 1 week of prednisolone therapy, and that these phenomena may be affected by plasma Fbg and VWF levels, respectively. The enhanced SIPA may play an important thrombogenic role in the acute phase of childhood MCNS.     

Low-dose cyclosporin therapy combined with prednisolone for relapsing minimal change nephrotic syndrome in adults

Low-dose cyclosporin(CsA) therapy combined with prednisolone was performed in 10 adult patients with frequently relapsing minimal change nephrotic syndrome(MCNS). Oral CsA was administered at the dose of 1-3 mg/kg/day(50-150 mg/day) in combination with preceding prednisolone(32.5 +/- 13.1 mg/day). The whole blood traugh concentration of CsA was maintained at the level of 50-100 ng/ml (ranging in 35-160 ng/ml, mean: 68.0 +/- 42.8 ng/ml), and the therapy was continued for 31.7 +/- 12.7 months. The urinary protein excretion, serum total protein, albumin and total cholesterol significantly improved after treatment. The serum creatinine increased slightly at 3-6 months after treatment, but decreased to within the normal range thereafter. The frequency of relapse and the ratio of the complete remission period to the total observed period were compared between the pre-treatment period(36.6 +/- 42.5 months) and post-treatment period(31.7 +/- 12.7 months). The frequency of relapse was significantly decreased after CsA treatment(2.3 +/- 1.5 times/year-->0.7 +/- 0.7 times/year, p = 0.02). The ratio of the complete remission period to the total observed period was increased significantly after CsA therapy(61.7 +/- 24.3%-->88.6 +/- 14.5%, p = 0.01). Thus, the low dose cyclosporin(CsA) therapy combined with prednisolone was an effective treatment for adult MCNS patients who relapsed frequently under conventional prednisolone therapy.     

Combined T- and B-cell activation in childhood steroid-sensitive nephrotic syndrome

BACKGROUND: Growing evidence shows that steroid-sensitive nephrotic syndrome (SSNS) is the result of a primary T-cell disturbance and leads to secondary anatomical and functional, however, not to immunological glomerular changes. In addition, immunoglobulin abnormalities in SSNS indicate a role of B-cell involvement. PATIENTS AND METHODS: We therefore analyzed T- and B-cell activation markers in children with SSNS at different stages of the disease including different treatment regimens by measuring the soluble IL-2 receptor (sCD25) and the soluble low-affinity IgE receptor (sCD23), respectively. Seventy-five patients with SSNS (median age 8.0, range 2.5 - 18 years) were studied, 33 in relapse (RL) including 21 patients relapsing during alternate-day steroids (RL-SD). Forty-two patients were studied in remission (RM; 14 off treatment and 28 on alternate-day steroids (RM-AD)) and 22 age-matched children served as controls. RESULTS: Serum concentrations of sCD25 were increased in RL (113.6 +/- 19.5 micromol/l) compared to RM (79.8 +/- 8 micromol/l, p < 0.02) and controls (74.8 +/- 0.9 micromol/l, p < 0.02). Patients with RL-SD did not have elevated sCD25. In relapse, sCD25 was inversely correlated with age (R = -0.36, p < 0.04) and positively correlated with total IgG (R = 0.37, p < 0.04). Urinary excretion of sCD25 was also significantly elevated in RL of SSNS compared to RM and controls (71.2 +/- 11.9 micromol/g creatinine vs. 39.1 +/- 4.8 and 32.0 +/- 4.2 micromol/g, p < 0.05). Serum levels of sCD 23 were significantly elevated in RL (6.22 +/- 0.65 microg/l) compared to RM (3.1 +/- 0.83 microg/l, p < 0.02) and to controls (3.4 +/- 0.93 microg/l). The highest values, however, were found in RL-SD (7.8 +/- 1.7 microg/l) vs. untreated RL (p < 0.007) and RM-AD (p < 0.002). In untreated RL there was a significant correlation of sCD23 and total IgE (R = 0.67, p < 0.02) and in RL-SD with total IgG (R = 0.45, p < 0.05). sCD23 and sCD25 were not correlated with each other. CONCLUSION: These data document parallel abnormalities of both CD23-mediated B as well as CD25-mediated T-cell activation and suggest that SSNS is not solely a disorder of T-cell dysfunction.     

Acute renal allograft rejection is associated with increased levels of vascular endothelial growth factor in the urine

AIM: The purpose of this study was to assess whether measurement of urinary vascular endothelial growth factor (VEGF) could be adopted as a new non-invasive diagnostic tool for acute rejection following renal transplantation. METHODS: Urinary concentration of VEGF was determined by an enzyme-linked immunosorbent assay technique in 215 renal allograft recipients and 80 healthy controls. RESULTS: Subjects with acute rejection (n=67) excreted urinary VEGF at a significantly higher level (28.57+/-6.21, 95% CI: 16.18-40.97 pg/mumol creatinine) than those without acute rejection. This included subjects with stable renal function and no abnormal histological findings (n=119), acute tubular necrosis (n=15), chronic allograft nephropathy (n=14) and healthy controls (n=80). Using a urinary VEGF/creatinine ratio of 3.64 pg/micromol as the cut-off point, the sensitivity and specificity for diagnosing acute rejection were 85.1 and 74.8%, respectively (P<0.001). Patients with steroid-resistant acute rejection had significantly greater urinary VEGF concentration than patients with steroid-sensitive acute rejection (42.09+/-10.00 vs 9.74+/-2.63 pg/micromol creatinine, P<0.001). Patients with graft loss after acute rejection had significantly greater urinary VEGF concentration than patients with reversible acute rejection (106.66+/-38.60 vs 19.46+/-4.13 pg/micromol creatinine, P=0.001). Using a urinary VEGF/creatinine ratio of 22.48 pg/micromol as the cut-off point, the sensitivity and specificity of the prediction to graft loss after acute rejection were 85.7% and 78.3%, respectively (P=0.001). CONCLUSION: This study demonstrates that the monitoring of urinary VEGF may be a useful non-invasive approach for the detection of acute rejection. Additionally, urinary VEGF levels were shown to predict the response to anti-rejection therapy and to predict a poor outcome after acute rejection.