Solution synthesis of core–shell Co9S8@MoS2 catalysts

Core–shell Co₉S₈@MoS₂ unsupported catalysts prepared by a solution reaction in ethylene glycol demonstrate high catalytic activity and exceptional thermal stability.

Can the height-independent Pottel eGFR equation be used as a screening tool for chronic kidney disease in children?

Determination of plasma creatinine (Pcr) should be associated to an estimation of glomerular filtration rate (eGFR). Pottel et al. established a height-independent equation, eGFR = 107.3/(Pcr/Q) where Q is the median of Pcr (Pottel-Belgium). The aims were to 1) determine a local height-independent equation (Pottel-Lyon), 2) evaluate the performance of these equations compared to the Schwartz 2009 and Schwartz-Lyon equations, and 3) evaluate the height-independent equations in laboratory routine. Therefore, 1) all first pediatric Pcr determination (December 2009-June 2011) were collected, and median of Pcr was determined for each 1-year age interval (Q-Lyon), 2) GFR was measured (mGFR) in 359 children (438 measures) and compared to eGFR, and 3) all first Pcr determination (January 2012-June 2013) were used to calculate eGFR with the Pottel-Lyon and the Pottel-Belgium equations. Pcr was determined by an IDMS-standardized enzymatic assay. In the population with a mGFR, the Pottel-Lyon and the Schwartz-Lyon showed the best performance (bias, P10 and P30). However, the performance in identifying patients with a mGFR < 75 mL/min/1.73 m(2) was similar for all the studied equations.

CONCLUSION

The performance of the height-independent and dependent equations to identify mild renal dysfunction is similar. The height-independent Pottel equation could be proposed as an excellent screening tool for kidney disease when height information is not available. "

WHAT IS KNOWN

" • Determination of plasma creatinine in children is rarely associated to an estimation of glomerular filtration rate due to the lack of height information. • Pottel et al. developed a height-independent equation (eGFR = 107.3/(Pcr/Q) where Q is the median of Pcr for each age class. "

WHAT IS NEW

" • The performance of the height-independent (Pottel) or height-dependent (Schwartz) equations is similar to identify renal dysfunction (GFR < 75 mL/min/1.73 m (2) ) in children. • The height-independent Pottel equation could be an excellent screening tool for kidney disease in a general pediatric laboratory when height information is not available.

A new equation to estimate the glomerular filtration rate in children, adolescents and young adults

BACKGROUND

A new estimated glomerular filtration rate (eGFR) equation, designed for isotope dilution mass spectrometry-standardized serum creatinine (Scr), is presented for use in children, adolescent boys and girls and young adults.

METHODS

The new equation, eGFR = 107.3/(Scr/Q), is based on the concept of normalized Scr: Q is the normalization value and is considered as the Scr concentration for the average healthy child, adolescent or young adult of a specific height (L) and is modeled as a height-dependent polynomial of the fourth degree.

RESULTS

The well-known Schwartz equation [eGFR = kL/Scr, k = 0.413 (Schwartz) or k = 0.373 (Schwartz-Lyon)] for children between 1 and 14 years can be seen as a special case of the new equation for which the Q-polynomial is simplified to a linear equation: Q = 0.0035 × L (cm). The new eGFR equation has been validated in a data set of n = 750 children, adolescents and young adults aged 10-25, against the true GFR (inulin method), and outperforms the selected (but most used) creatinine-based eGFR equations for children, mainly in the healthy GFR region.

CONCLUSIONS

The new Q(height)-eGFR equation serves as an excellent screening tool for kidney disease in 1-25-year-old children, adolescents and young adults.

Deferasirox-induced renal impairment in children: an increasing concern for pediatricians

BACKGROUND

Deferasirox (DFX) is an oral iron chelator with an established dose-dependent efficacy in transfusion-related iron overload. Whereas emerging long-term data confirm the safety of the drug, with transient moderate elevation of serum creatinine level, several authors have reported renal tubular dysfunction. The aim of this study was to evaluate tubular and glomerular function before and after the initiation of DFX therapy in a pediatric patient population.

METHODS

Ten children (4 girls, mean age 12.4 ± 3.9 years) enrolled in a routine blood transfusion program were treated with 24.8 ± 9.6 mg/kg per day of DFX, and renal function was assessed before and 17.2 ± 8.9 months after the initiation of DFX therapy.

RESULTS

Prior to treatment with DFX, all patients had a normal glomerular function rate (GFR) (125 ± 15 ml/min per 1.73 m(2)) and normal tubular function. Following the initiation of DFX therapy, the GFR decreased by approximately 20 % with one patient with a GFR of <80 mL/min per 1.73 m(2) and seven patients with a GFR of <100 mL/min per 1.73 m(2). Two patients experienced a generalized proximal tubular dysfunction whereas nine patients presented at least one sign of proximal tubular dysfunction.

CONCLUSIONS

Renal toxicity is a frequent adverse event of DFX treatment, presenting as both glomerular and proximal dysfunction. A routine renal assessment is therefore required to prevent chronic kidney disease that may result from prolonged tubular injury.

Performance of the chronic kidney disease epidemiology collaboration equation to estimate glomerular filtration rate in diabetic patients

OBJECTIVE

The best method to estimate glomerular filtration rate (GFR) in diabetic patients is still largely debated. We compared the performance of creatinine-based formulas in a European diabetic population.

RESEARCH DESIGN AND METHODS

We compared the performance of Cockcroft and Gault, simplified Modification of Diet in Renal Disease (MDRD), and Chronic Kidney Disease Epidemiology (CKD-EPI) Collaboration equations in 246 diabetic patients by calculating the mean bias and the interquartile range (IQR) of the bias, 10% (P10) and 30% (P30) accuracies, and Bland-Altman plots. GFR was measured by inulin clearance.

RESULTS

For the whole population, the IQR was slightly lower for CKD-EPI, but the mean bias was lower and P10 and P30 were higher for MDRD. Similar results were observed in specific subgroups, including patients with mild renal insufficiency, obese patients, or type 2 diabetic patients.

CONCLUSIONS

In our population, the CKD-EPI formula does not exhibit better performance than the simplified MDRD formula for estimating GFR.

Familial nephrogenic syndrome of inappropriate antidiuresis: dissociation between aquaporin-2 and vasopressin excretion

CONTEXT

Nephrogenic syndrome of inappropriate antidiuresis (NSIAD), the X-linked disease resulting from activating mutation of the vasopressin V2 receptor gene (AVPR2), is a recently described condition causative of episodes of hyponatremia in boys and male and female adults.

OBJECTIVE

The objective of the study was the pathophysiological characterization of NSIAD.

DESIGN

A family with NSIAD was identified and investigated for hyponatremic episodes and degrees of urine dilution defects. For the first time, the impact of the mutated V2R on aquaporin 2 (AQP2) excretion is reported.

SETTING

The study was conducted at a referral center.

PATIENTS

Five patients of seven carriers (two young brothers and their mother and her two sisters) were investigated together with age-matched controls.

INTERVENTIONS

There were no interventions.

RESULTS

In NSIAD patients, urinary AQP2 excretion occurred independently of concomitant vasopressin excretion and strongly correlated with urine osmolality, confirming direct AQP2 involvement in urine concentration. Water loading was followed by a very slow and incomplete elimination in the asymptomatic hemizygous boy with no suppression of AQP2 excretion and a delayed elimination in the heterozygous women because of an incomplete suppression of AQP2, and it induced hyponatremia in all NSIAD patients. Two hemizygous carriers presented with severe hyponatremia-induced seizures, and the repetition in one of them led to mental retardation.

CONCLUSIONS

Hyponatremia was a constant and characteristic aspect of the abnormal response to even mild water-loading tests in an asymptomatic hemizygous child as well as heterozygous adults. We confirm the phenotypic variability of NSIAD, a disease that should be regarded in pediatric intensive care units in presence of severe and/or recurrent hyponatremia, and also in adults, because carriers are prone to hyponatremia.

What is the best alternative to inulin clearance to estimate GFR in patients with decompensated alcoholic cirrhosis?

BACKGROUND

Accurate evaluation of the glomerular filtration rate (GFR) in patients awaiting liver transplantation is important because they have a greater risk of impaired renal function. A major percentage of these patients have alcoholic cirrhosis, and the accuracy of bedside used GFR estimates have not been specifically evaluated in this group. The aim of this study was to evaluate the validity of the simplified Modification of Diet in Renal Diseases (MDRD) and Cockcroft and Gault (CG) formulas in patients with decompensated alcoholic cirrhosis in comparison to inulin clearance as the reference method.

METHODS

GFR estimated by the simplified MDRD and CG formulas were retrospectively compared to the true GFR measured by inulin clearance in a single-centre cohort of 148 patients with decompensated alcoholic cirrhosis.

RESULTS

Mean ± standard deviation of age, body mass index, inulin clearance and MDRD and CG estimates were 54.4 ± 6.9 years, 26.5 ± 4.7 kg/m(2), 76.9 ± 28.0 mL/min per 1.73 m(2), 99.4 ± 34.0 mL/min per 1.73 m(2) and 98.7 ± 32.0 mL/min per 1.73 m(2), respectively; 70% of the patients had a GFR, measured by inulin clearance, below 90 mL/min per 1.73 m(2). The difference between estimated GFR and true GFR were 23 ± 23 mL/min per 1.73 m(2) for MDRD and 22 ± 20 mL/min per 1.73 m(2) for Cockcroft and Gault.

CONCLUSIONS

The simplified MDRD and CG formulas largely overestimated GFR in patients with decompensated alcoholic cirrhosis. Results of such bedside formulas should be interpreted with caution in these patients.

Hyperuricemia after liver transplantation in children

Uric acid may be involved in the development and progression of kidney diseases. Hyperuricemia is a common feature in adult liver transplant recipients but there is limited information in children. In order to estimate the incidence, predictors of hyperuricemia in pediatric liver transplant recipients, and to assess whether hyperuricemia may impact long-term renal function determined by measured GFR, we reviewed data of 70 children who received a first liver transplant between 1991 and 2005 (median follow-up 7.1 yr). Renal function tests performed annually included uric acid concentration, inulin and uric acid clearances. The cumulative incidence of hyperuricemia was 32% at 10-yr post-transplantation, mainly because of decreased urate excretion. The only factor significantly associated with an increased risk of hyperuricemia was older age. After adjustment for donor and recipient age, gender, primary liver disease, immunosuppression, and post-operative acute renal failure, hyperuricemia as time dependent variable tended to predict (p = 0.05) subsequent CRI. The control of serum urate concentration in eight of the 21 hyperuricemic patients either by nutritional management or by allopurinol was not followed by a significant GFR improvement. Hyperuricemia after liver transplantation in children is a frequent problem which needs further investigation.

Relationship between serum carnitine, acylcarnitines, and renal function in patients with chronic renal disease

BACKGROUND

Serum free carnitine is decreased and serum acylcarnitines are increased in maintenance hemodialysis (MHD) patients, and the causes for these abnormalities are not known. This study examined the role of renal failure in the occurrence of low serum carnitine and increased acylcarnitines in patients with advanced chronic kidney disease (CKD) by assessing the relationship between these compounds and renal function in normal individuals and patients with CKD. If these compounds decrease as glomerular filtration rate (GFR) decreases, this suggests that decreased intake or impaired synthesis in kidneys explain the low serum values. If serum compounds increase as GFR decreases, this suggests that impaired excretion may predispose to these values.

METHODS

The study, conducted in Lyon, France (part A), and Los Angeles, California (part B), compared serum free carnitine and acylcarnitines to renal function in 20 normal patients, 65 CKD patients, and 29 MHD patients. GFR was measured using inulin (A) and iothalamate (B) clearances. Carnitine compounds were measured by tandem mass spectrometry (A) and electron spray mass spectrometry (B).

RESULTS

There was no relationship between serum total carnitine or free carnitine and GFR in the normal subjects and CKD patients. In contrast, serum acylcarnitines were inversely correlated with GFR in these 2 groups. Serum free carnitine was significantly lower in MHD patients than in CKD patients and normal controls in study B, whereas acylcarnitines were significantly greater than controls in studies A and B and than in CKD patients in study A.

CONCLUSIONS

Serum free carnitine is not reduced in CKD and decreases in MHD patients. Serum acylcarnitines increase in CKD and MHD patients primarily because of impaired excretory function in the failing kidney.

Predicted creatinine clearance to evaluate glomerular filtration rate in black Caribbean subjects

BACKGROUND AND METHODS

Although Caribbean people have been a lesser-studied ethnic group than other populations, they have a high burden of hypertension and renal disease. Because Caribbean people have a greater muscle mass than Caucasians, this study examined the accuracy of creatinine-based estimates (creatinine clearance; C(cr) and Cockcroft-Gault formula; C-G Cl) of glomerular filtration rate (GFR) in 38 Caribbeans who were matched for age, gender, and GFR, with 38 Caucasian subjects. Patients were considered black Caribbean if at least one of two parents was of black Caribbean origin. GFR values ranging from 5 to 140 ml/min/1.73 m(2) were measured by inulin clearance. Results were compared using linear correlations and the Bland and Altman methodology to provide better estimates of value dispersion.

RESULTS

Correlation coefficients between C-G Cl and GFR were highly significant in both black Caribbean subjects (r=0.83, P<0.001) and Caucasians (r=0.84, P<0.001). Similar coefficients were obtained between C(cr) and GFR (r=0.89, P<0.001 and r=0.90, P<0.001, respectively). In spite of these strong correlations, the Bland and Altman representation highlighted huge intra-individual variations in GFR estimation by C-G Cl and by C(cr) in both ethnic groups. The underestimation of GFR by C-G Cl was significant in black Caribbeans (-8.6+/-20 ml/min/1.73 m(2), P<0.001) but not in Caucasians (-5.6+/-20.7 ml/min/1.73 m(2)). C(cr) overestimation of GFR was significant both in Caribbeans (8.7+/-16.8 ml/min/1.73 m(2), P<0.001) and in Caucasians (7.2+/-15.7 ml/min/1.73 m(2), P<0.01).

CONCLUSIONS

The C-G formula for estimating GFR yields similar clinical values in black Caribbeans and in Caucasians, but the same limitations were observed in both ethnic groups.

[Target organ effects in untreated hypertension]

The parallel investigation of the renal and cardiac complications of recent and never treated systemic hypertension has only rarely been undertaken. The aim of this study was to define the renal function of never treated hypertensive subjects, separated into white coat hypertensives (HTbb: n = 19, BP at consultation 153/97 mmHg) or permanent hypertensives (HT: n = 49, BP at consultation 169/104 mmHg) as a function of their 24 hour BP. Their renal functions were then compared with those of normotensive subjects (NT: n = 10). The 68 hypertensive subjects seen consecutively underwent renal function investigation (DFG: glomerular filtration rate, DPR: renal plasmatic debit, and muAlb: microalbuminuria over 24 hours), and myocardial echography (measurement of the left ventricular mass index, IMVG). The white coat hypertensives had a normal renal function, while the permanent hypertensives had a significant decrease in DPR and a significantly higher muAlb compared to the normotensives. Compared to the white coat hypertensives, the permanent hypertensives had a significantly lower DFG and DPR, as well as a higher muAlb and IMVG. In all the hypertensives (white coat and permanent) the 24 hour systolic BP was significantly correlated with muAlb (r = 0.51, p < 0.001), filtration fraction (r = 0.30, p < 0.05), and IMVG (r = 0.52, p < 0.001). The renal and myocardial parameters were not significantly correlated. In conclusion, there seems to be a continuum between the level of ambulatory BP and the effect on target organs without a parallel progression of the renal and myocardial effects. From a practical point of view, only ambulatory BP measurement allows differentiation of permanent hypertensives who have a very early renal and/or myocardial effect, while white coat hypertensives are spared.

Better long-term functional adaptation to the child's size with pediatric compared to adult kidney donors

BACKGROUND

Pros and cons for pediatric kidney donors have been debated, especially with respect to survival rates. However, the effect of donor age on kidney function remains conflicting. The aim of this study was to compare short and long-term renal function according to the age of the donor, in grafts from adult living related (LRD), adult cadaveric and pediatric cadaveric donors (PedCD) following pediatric transplantation (Tx).

METHODS

One hundred and thirty-four children were repeatedly followed for four years, and 44 were followed for eight years. Absolute and relative glomerular filtration rate (GFR; inulin clearance, mL/min and mL/min/1.73 m(2), respectively) were determined within 6 months, and yearly thereafter.

RESULTS

Absolute GFR increased along with body growth in the PedCD group (P < 0.001) during the 4 years following Tx, leading to stable relative GFR, whereas absolute GFR of the LRD group did not change, with a progressive decrease of relative GFR (P < 0.001). Relative GFR did not differ between PedCD and LRD recipients by the sixth month but became higher in PedCD 4 years post-Tx (70 +/- 25 vs 52 +/- 19 mL/min/1.73 m(2), P < 0.001). Among those followed for 8 years, relative GFR showed a slow decrease in both recipient groups from 6 years post-Tx. At 8 years post-Tx, relative GFR was still significantly higher in PedCD than in LRD (57 +/- 19 vs. 45 +/- 19; P < 0.05).

CONCLUSIONS

Adult-sized grafts may adapt to pediatric recipients during the first months post-Tx, but graft function cannot improve thereafter along with the increase in body size of the recipient. Interestingly, the absolute GFR of children receiving pediatric grafts increased along with body growth, leading to a stable relative GFR up to 6 years post-Tx.

A preservation solution with polyethylene glycol and calcium: a possible multiorgan liquid

The addition of polyethylene glycol (PEG) to hepatocyte storage medium is known to decrease lipid peroxidation and swelling and to protect the cell cytoskeleton from cold. We therefore decided to investigate the effect of substituting PEG for hydroxyethyl starch (HES) in an extracellular-like UW solution, with and without Ca++, on rat liver preservation. Isolated perfused rat livers were used to assess graft injury after 24h of cold storage. Four groups of preserved livers ( n=6 for each group) were compared to controls (non preserved livers, n=11). For this purpose, Belzer solution (K+-UW, group 1) was stepwise modified. Group 2 (Na+-UW) was treated with the same liquid, however with inverted concentrations of Na+ and K+. Group 3 was preserved in the first experimental solution (EPS-1) with Ca++ (0.5mM) added to the Na+-UW solution. In the EPS-2 (group 4), PEG-35 (0.03mM) was substituted for HES. The last group, EPS-3 (group 5) was treated with the same compounds as EPS-2, but without Ca++. After 24h of cold storage and 120min normothermic reperfusion, there was no statistical difference in transaminases (ALT and AST) release between the control and the Na+-UW groups. Furthermore, rat livers preserved in Na+-UW solution released less ( P<0.05) ALT and AST and excreted more ( P<0.05) indocyanine green (ICG) than livers preserved in K+-UW solution. The addition of 0.5mM Ca++ to Na+-UW solution (EPS-1) dramatically increased ( P<0.05) parenchymal (ALT, AST) and non parenchymal (creatine kinase-BB) cellular injury. The substitution of PEG (0.03mM) for HES (EPS-2) reduced ( P<0.05) membrane injuries due to Ca++ while bile flow was statistically increased ( P<0.05). Finally, the omission of Ca++ from EPS-2, that is EPS-3, has no statistically significant effect on the studied parameters. PEG effectively protected the rat liver grafts from the onset of hypothermic ischemia-reperfusion and Ca++ damages and thus may be a valuable additive to preservation solutions.

A preservation solution with polyethylene glycol and calcium: a possible multiorgan liquid

The addition of polyethylene glycol (PEG) to hepatocyte storage medium is known to decrease lipid peroxidation and swelling and to protect the cell cytoskeleton from cold. We therefore decided to investigate the effect of substituting PEG for hydroxyethyl starch (HES) in an extracellular-like UW solution, with and without Ca++, on rat liver preservation. Isolated perfused rat livers were used to assess graft injury after 24h of cold storage. Four groups of preserved livers ( n=6 for each group) were compared to controls (non preserved livers, n=11). For this purpose, Belzer solution (K+-UW, group 1) was stepwise modified. Group 2 (Na+-UW) was treated with the same liquid, however with inverted concentrations of Na+ and K+. Group 3 was preserved in the first experimental solution (EPS-1) with Ca++ (0.5mM) added to the Na+-UW solution. In the EPS-2 (group 4), PEG-35 (0.03mM) was substituted for HES. The last group, EPS-3 (group 5) was treated with the same compounds as EPS-2, but without Ca++. After 24h of cold storage and 120min normothermic reperfusion, there was no statistical difference in transaminases (ALT and AST) release between the control and the Na+-UW groups. Furthermore, rat livers preserved in Na+-UW solution released less ( P<0.05) ALT and AST and excreted more ( P<0.05) indocyanine green (ICG) than livers preserved in K+-UW solution. The addition of 0.5mM Ca++ to Na+-UW solution (EPS-1) dramatically increased ( P<0.05) parenchymal (ALT, AST) and non parenchymal (creatine kinase-BB) cellular injury. The substitution of PEG (0.03mM) for HES (EPS-2) reduced ( P<0.05) membrane injuries due to Ca++ while bile flow was statistically increased ( P<0.05). Finally, the omission of Ca++ from EPS-2, that is EPS-3, has no statistically significant effect on the studied parameters. PEG effectively protected the rat liver grafts from the onset of hypothermic ischemia-reperfusion and Ca++ damages and thus may be a valuable additive to preservation solutions.

Fading renal hyperfiltration in children following liver transplantation

In a prospective longitudinal study, we investigated the renal function (RF) of 23 children before and after orthotopic liver transplantation (OLT). The aim was to assess both the outcome of pretransplant hyperfiltration and the clinical nephrotoxic effects of cyclosporin A (CsA); children with decreased RF prior to OLT were therefore excluded. The RF study of the 13 remaining patients included glomerular filtration rate (GFR) and effective renal plasma flow (RPF) measured by inulin (Cin: mL/min/1.73 m2) and para-amino hippurate (Cpah: mL/min/1.73 m2) clearances, respectively. Hyperfiltration prior to OLT was observed in six children, i.e. Cin>170 [range 172-230] and Cpah>800 [808-1,133]. A significant decrease in RF was noted as soon as 6 months after OLT: Cin (mean+/-SD)=107+/-23 vs. 158+/-46 (p<0.003); Cpah=583+/-119 vs. 791+/-243 (p<0.004). This was due to loss of hyperfiltration in the six children, as there was no significant difference in RF before and 6 months after OLT in the other seven children. With a 36-month follow-up, there was no correlation between CsA trough blood level and RF. In conclusion, following OLT, RF underwent early changes owing to loss of prior hyperfiltration in children without impaired RF before OLT. In addition, no evidence of CsA nephrotoxicity was found and RF remained stable during follow-up.

Vesicoureteral reflux after kidney transplantation in children

BACKGROUND

The prevalence and significance of vesicoureteral reflux (VUR) after kidney transplantation in adults varies between authors and there have been few reports in children.

METHODS

We conducted a retrospective study in a single-centre paediatric cohort. Fifty-five of the 84 children who underwent kidney transplantation over a 5-year period were checked with routine cystography after a median of 8 months post-transplantation. Graft function and urinary-tract infections were assessed during the first 6 years after transplantation.

RESULTS

VUR into the graft was present in 58% of the patients. Graft function and incidence of urinary-tract infections were similar in the two groups, independent of VUR. After having excluded infections attributed to the presence of a catheter, actuarial survival rates without pyelonephritis and without pyelonephritis following a first lower urinary-tract infection were worse in patients with VUR (P:=0.017 and P:=0.0039 respectively). None of the eight patients with VUR treated with antibiotic prophylaxis after a first acute pyelonephritis (APN) episode presented subsequent APN after 4.4+/-3.3 years on therapy.

CONCLUSIONS

VUR to the graft occurred in more than half paediatric renal transplant recipients. This condition was associated with an increased risk of APN. Long-term antibiotic prophylaxis seems to be able to prevent APN in transplanted children with VUR.

Renal function of children exposed to cyclosporin in utero

BACKGROUND

The use of cyclosporin (CsA) has improved graft survival in transplant (Tx) patients despite its potential nephrotoxicity. Children born to transplanted women may present with intrauterine growth retardation (IUGR). On the basis of potential reduced nephron mass both in IUGR and in newborn experimental animals exposed to CsA in utero, we investigated the renal function of children >1 year of age born to women under maintenance immunosuppression, including CsA.

METHODS

Fourteen children born to 12 Tx women (nine kidney, one pancreas-kidney, one heart, one liver) were investigated using inulin clearance (C(in)), para-aminohippuric acid clearance (C(PAH)), microalbuminuria, and electrolyte reabsorption rate.

RESULTS

Gestational age of the 14 infants was 34+/-3 weeks and birth weight 2018+/-620 g. During pregnancy, CsA trough blood level was 234+/-115 microg/l and plasma creatinine range was 96-136 micromol/l. Two children were excluded from the study because renal investigation led to a diagnosis of hereditary nephritis (one Alport syndrome, one familial dominant focal segmental glomerulosclerosis) that was retrospectively completed in the mother. Renal function tests were finally performed in 12 children at 2.6+/-1.8 years of age: BP 94+/-7/55+/-5 mmHg, C(in) 117+/-28 ml/min/1.73 m(2), C(PAH) 545+/-124 ml/min/1.73 m(2), filtration fraction 0.23+/-0.03, microalbuminuria 4.2+/-3.5 mg/mmol. Electrolyte tubular reabsorption rates and urine concentrating capacity were normal.

CONCLUSION

These results suggest that in children born to transplanted women taking CsA, renal function develops normally despite prolonged exposure in utero.

Renal function and urinary excretion of electrolytes in patients receiving cyclic parenteral nutrition

BACKGROUND

Long-term parenteral nutrition (LTPN) has been shown to induce renal impairment and bone demineralization. However, the mechanism of both injuries has not been clarified.

METHODS

This prospective study was performed in 16 patients with short bowel syndrome, aged 28 to 63 years, who had received LTPN for 31 +/- 7 months. Urinary excretion of electrolytes were measured before (diurnal, 12 hours) and during (nocturnal, 12 hours) parenteral nutrition. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured in the morning after the nutritional bag supply.

RESULTS

Mean GFR was 86 +/- 7 mL/min/1.73 m2 and ERPF was 412 +/- 31 mL/min/1.73 m2. Decreased GFR was present in 9 patients. There was no relation between renal function and age or the duration of LTPN. Urine volume and excretion of urea, creatinine, sodium, magnesium, and phosphate but not potassium increased significantly in nocturnal urine compared with diurnal urine. On the basis on 24-hour calciuria, 7 patients were normocalciuric (NCa) whereas 9 were hypercalciuric (HCa). Both had excessive nocturnal calciuria, but only the HCa group had diurnal hypercalciuria, the calcium supply being identical. Bone mineral density (BMD) was slightly, although not significantly, higher in NCa group, but in all patients BMD correlated significantly with calciuria. Serum parathyroid hormone and vitamin D were not different in the two groups.

CONCLUSIONS

In patients receiving LTPN, renal function is frequently impaired, by a mechanism which remains unclear. In nocturnal cyclic mode of nutrition, urinary volume and electrolyte excretion occurred predominantly during the infusion, but some patients have diurnal hypercalciuria. In these patients a defect in renal calcium reabsorption or more likely the inability of bone to retain the infused calcium may be responsible for bone demineralization.

Long-term nephrotoxicity of cisplatin, ifosfamide, and methotrexate in osteosarcoma

The acute renal effects of chemotherapy are known, but long-term nephrotoxicity has rarely been investigated. The aim of the present study was to assess long-term renal function in children and adolescents who received at-risk chemotherapy, including cisplatin, ifosfamide, and methotrexate, to treat an osteosarcoma. Renal function tests [creatinine clearance, microalbuminuria, and renal excretion of sodium, potassium, chloride, calcium, magnesium (Mg), phosphorus (P), and uric acid] were prospectively performed 5.4+/-2.2 (+/-SD) years after chemotherapy (total cumulative dose: methotrexate 41+/-31 g/m2, ifosfamide 39+/-14 g/m2, cisplatin 674+/-188 mg/m2) in 18 children and adolescents. The results were compared with 13 normal volunteers matched for age and sex. Creatinine clearance, which was greater than 80 ml/min per 1.73 m2 in all patients, correlated with the total dose of ifosfamide (r=0.55, P<0.05) and cisplatin (r=0.48, P<0.05). Microalbuminuria was noted in 4 patients. Hypomagnesemia was present in 4 and hypercalciuria in 3 patients; renal excretion of P, Mg, and uric acid was higher in patients than in controls. Glomerular function was not significantly altered and only mild tubular dysfunction was present. Since renal excretion of P and Mg were increased in patients compared with normal volunteers and hypercalciuria was occasionally seen, divalent ion disorders are the most-likely potential complications.

Role of the donor in post-transplant renal function

BACKGROUND

The donor, i.e. adult or paediatric, might influence the outcome of the graft function.

METHODS

The glomerular filtration rate (GFR) of 120 transplanted children (47 girls) aged 10.4+/-4.6 years (0.7-17.2) was prospectively assessed over a 5-year period. The patients were divided into two groups according to the age of donor: adult (donor age > 18 years; n=33) and paediatric (donor age < 18 years; n=87). GFR was assessed by inulin clearance at 3, 6 and 12 months and yearly thereafter.

RESULTS

The average GFR was stable in the range of 70 ml/min/1.73 m2 for the whole follow-up period. The adjusted GFR in adult graft recipients was significantly higher at 3 months post-transplantation: 80.6+/-36.9 vs 65.1+/-22.0, P=0.02. However, from the second year post-transplantation, the adjusted GFR in paediatric graft recipients became significantly higher than that of adult graft recipients. Such results could be due to an improvement in the absolute GFR (ml/min) of paediatric graft recipients with time (P=0.0001) whereas that of the adult graft recipients remained stable despite the children's growth.

CONCLUSIONS

The adjusted GFR of adult graft recipients was significantly higher than that of paediatric graft recipients in the early post-transplant period. In the long-term, a progressive decrease in adjusted GFR was noted in adult graft recipients. On the one hand, this may be due to a functional adaptation and/or inadequate compensatory growth of the graft. On the other hand, the absolute GFR of paediatric graft recipients increased, suggesting an ongoing capacity for growth and/or compensatory hypertrophy after child-to-child renal transplantation.

[Graft function following renal transplantation in children]

BACKGROUND

Since renal transplantation is known to be the best choice for the growing child with end-stage renal failure, we prospectively evaluated early and late graft function in transplanted children.

POPULATION AND METHODS

The study included 78 children (32 girls, 46 boys) 10.4 +/- 0.6 years at the time of transplantation. Renal investigations were performed at 3, 6 and 12 months post-transplantation and yearly thereafter. Inulin clearance was used to evaluate the glomerular filtration rate (GFR), and the reabsorption rates of Na, P and Ca were measured concomitantly.

RESULTS

The overall adjusted GFR was approximately 70 mL/min/1.73 m2 and remained unchanged during the first 5 years post-transplantation. In the mean time the absolute GFR increased significantly, suggesting a remaining capacity for compensatory hypertrophy of the transplanted kidney. Renal function was significantly influenced by the number of rejection episodes during the first 2 years post-transplantation but no correlation was found between GFR and the number of HLA mismatches or the use of preemptive transplantation.

Outcome of preemptive renal transplantation and pretransplantation dialysis in children

The present study compares the outcome of 40 children (39%) transplanted without prior dialysis, i.e., preemptive transplantation (PET), with 63 children (61%) transplanted after a variable duration of dialysis, i.e., pretransplantation dialysis (PTD). The two groups were matched for recipient and donor age and for immunological risk factors. There was no statistical difference in the time to first acute rejection episode nor in the number of acute rejection episodes during the 1st year after renal transplantation. In the PET group, 78% of the recipients received blood transfusion versus 92.5% in the PTD group (P < 0.05), and the average number of blood units per patient was 3.2 and 7.8, respectively (P < 0.05). Arterial hypertension was found in 55% of the patients in the PET group versus 73% in the PTD group (P < 0.05). The number of functioning grafts at the end of the study period was 87.5% in the PET group and 73% in the PTD group (NS). The major cause of graft failure was vascular thrombosis in the PET group (3/5) and chronic allograft rejection in the PTD group (10/17). In the PET group, the actuarial graft survival rate was 100%, 84%, 81%, and 76% at 1, 3, 5, and 7 years, which was not statistically different from the PTD group at 1, 3, and 5 years (98%, 91%, and 73%, respectively) but there was a significantly lower graft survival (59%) after 7 years in the PTD (P < 0.05). The 7-year actuarial patient survival rate was 97% in the PET group and 90% in the PTD group (NS). In the PTD group, children on dialysis for less than 1 year (group 1, n = 25) were compared with those on dialysis for more than 1 year (group 2, n = 38). Arterial hypertension was noted in 40% of patients from group 1 and 65% from group 2 (P < 0.05); there was no significant difference in graft loss rate. In conclusion, these results confirm PET as the preferred approach rather than PTD in children who need renal replacement therapy.

[Renal function after nephrectomy for Wilms' tumor]

BACKGROUND

Most children with Wilms tumour recover after nephrectomy, chemotherapy and sometimes radiotherapy. It is therefore important to assess their long-term renal function.

POPULATION AND METHODS

Thirty-three patients with Wilms tumour experienced unilateral nephrectomy between 1986 and 1993: three were excluded; 23 were staged as grade I, one at grade II, two at grade III and four at grade IV. They were treated with SIOP 6 and SIOP 9 protocols. The results were compared to five controls who underwent unilateral nephrectomy including three for renal trauma. The glomerular filtration rate (GFR) was measured by inulin clearance and the renal plasma flow (RPF) by para-amino-hippuric acid clearance.

RESULTS

The mean age at nephrectomy was 3.4 +/- 2.5 years (median: 3, range: 0.2-10.6) and the duration of follow-up was 4.6 +/- 3.1 years (median: 4.5, range: 1-8.5), the GFR was 93 +/- 13 mL/min/1.73 m2 (median: 93, range: 73-130), the RPF was 441 +/- 85 mL/min/1.73 m2 (median: 453, range: 236-650) and the filtrated fraction (FF) was 0.21 +/- 0.03 (median: 0.20, range: 0.18-0.31). The difference in renal function between patients and controls was not significant (GRF: 86 +/- 12 mL/min/1.73 m2, RPF: 486 +/- 185 mL/min/1.73 m2, FF: 0.22 +/- 0.03). The electrolyte reabsorption rate was normal and none of the patients suffered from arterial hypertension. Fourteen children had urinary albumin: creatinine ratio > 2 g/mol. When comparing patients according to the duration of follow-up after nephrectomy (< 4 years vs > 4 years), the renal function was not statistically different. The age at nephrectomy (< 2 years vs > 2 years) did not increase the risk of renal impairment.

CONCLUSION

Children with Wilms tumour who were treated with nephrectomy and non-nephrotoxic drugs (actinomycin, vincristine, epiadriamycin) have a good long-term renal outcome. It is speculated that systematic renal investigation should be limited to those children with increased microalbuminuria and/or elevated blood pressure.

Nifedipine improves recovery function of kidneys preserved in a high-sodium, low-potassium cold-storage solution: study with the isolated perfused rat kidney technique

BACKGROUND

Extracellular types (high-Na) of cold-storage solution (CSS) have been shown to be more effective in preserving kidneys than intracellular CSS (high-K). On the other hand, calcium entry blockers (CEB) have been demonstrated to improve graft function when administered after and/or prior to transplantation. The ischaemia reperfusion syndrome involves, in part, an alteration in intracellular calcium metabolism that induces an increase in renal vascular resistances (RVR) and other cellular dysfunction, and high-K CSS per se are vasoconstrictive. Since CEB act via a modification in intracellular calcium metabolism on vascular smooth muscle, glomerular, and tubular cells, we evaluated the actual benefit on CEB on kidneys preserved in Belzer's CSS (K-UW) and a high-Na version of Belzer's CSS (Na-UW).

METHOD

The isolated perfused rat kidney (IPK) was used, first as a vascular bed to test the effects of CSS on RVR, and the influence of nifedipine. Second, the recovery function of the IPK was assessed by GFR and tubular Na reabsorption, after 24 h preservation in K-UW and Na-UW, with or without nifedipine. Results were compared with a control group in which renal function was measured without prior cold-storage.

RESULTS

K-UW but not Na-UW induced an increase in RVR when flushed into the kidney. This vasoconstriction is prevented by nifedipine. K-UW CSS was more deleterious to renal function than Na-UW. Addition of nifedipine to the flush, the CSS for 24 h, and to the normothermic reperfusate further improved recovery function of the IPK cold stored in Na-UW but not in K-UW, without any modification of RVR.

CONCLUSION

Nifedipine may be of potential effect in attenuating ischaemic injury by a mechanism which does not involve its vasodilatory properties.

Body composition and physical performance in children after renal transplantation

Body composition using standard anthropometric methods and dual-energy X-ray absorptiometry (DEXA) was determined in a cross-sectional study among 26 pediatric renal transplant recipients. At the same time, spiroergometry exam, pulmonary function tests, dynamometry and tremometry exams were performed in all patients. Fat body mass obtained by DEXA correlated inversely with maximal physical load during spiroergometry exam (r2 = 0.51, p = 0.0001). The study demonstrates good tolerance of increased physical load in children after renal transplantation. An inverse relationship was found between fat body mass and physical performance. Exercise training programs for children after renal transplantation are therefore suggested.

Body composition in children with renal disease: use of dual energy X-ray absorptiometry

Dual energy X-ray absorptiometry (DEXA) is a non-invasive accurate method which estimates bone mineral content and density (BMD), as well as fat (FM) and lean (LM) body mass. This method was used in control children in order to establish normal values for BMD of lumbar spine and whole body composition ¿logistic curves, general equation E = k+K/[1+ alpha exp(- beta A)]¿. In children with chronic renal failure (CRF), LM correlated with the urinary excretion of creatinine (r = 0.97, P = 0.0001) independently from glomerular filtration rate. However, the assessment of LM by DEXA must take into account the hydration level, since there is a positive correlation between fluid loss and reduction in LM in children on hemodialysis (r = 0.98, P = 0.0001). After renal transplantation, a significant loss of BMD (median -9.2%) was observed at 6 months which returned to 95% of pretransplant values by the end of the 1st year. Maximal changes in LM and FM occurred during the first 3 months (-7.8% and +7.2%, respectively) and may be due to steroids; these should be influenced by physical activity since FM correlated inversely with maximal oxygen consumption (r = 0.69, P = 0.0001). Recombinant growth hormone treatment could also increase LM and decrease FM, as shown in 9 patients. DEXA appears therefore to be a reliable method for evaluating therapeutic interventions affecting nutritional status in children with CRF.

[Recombinant human growth hormone (rhGH) administration in a patient with chronic renal insufficiency: renal and metabolic effects]

We report the renal and metabolic effects of a 40 day administration of recombinant human growth hormone in a 31 years old diabetic and GH-deficient patient who underwent a kidney and pancreas transplantation. The data show an increase in glomerular filtration rate, tubular reabsorption of phosphate, and plasma hemoglobin level. Anabolism is suggested from a decrease in serum urea nitrogen and an increase in muscle mass (increase in plasma creatinine). These positive effects might be partly explained by an overcome of endogenous growth hormone resistance when administering pharmacological doses of recombinant growth hormone.

Renal function following unilateral nephrectomy for neuroblastoma and Wilms' tumour

To estimate the side effects of chemotherapy and the influence of age at the time of nephrectomy on renal function, we investigated renal function in 34 uninephrectomised children with neuroblastoma (NB) or Wilms' tumour (WT). The results were compared with 6 controls who underwent nephrectomy for non-malignant disease. Study of renal function was primarily based on the clearance of inulin and para-aminohippuric acid (Cin and CPAH, ml/min per 1.73 m2). No significant differences in Cin/CPAH (mean +/- SD) were found between the NB group (90 +/- 24/421 +/- 95), WT group (85 +/- 17/386 +/- 104) and the controls (93 +/- 13/430 +/- 61). Children with NB and WT were divided into two subgroups according to the theoretical nephrotoxic risk. There was no significant difference in renal function between NB or between WT subgroups. Cumulative cisplatin doses in children with NB did not affect renal function significantly. The age at time of unilateral nephrectomy (< or = 2 years vs. > 2 years) was not associated with a higher risk of renal damage in WT children, whereas in NB children the filtration fraction (Cin:CPAH) was higher in younger children (mean +/- SD: 0.243 +/- 0.023 vs. 0.191 +/- 0.041). In conclusion, uninephrectomised children with NB are supposed to have a higher risk of drug-induced renal impairment compared with those with WT. Our data do not confirm this hypothesis, since renal function was comparable to controls in both groups, except in younger patients with NB who show a high filtration fraction. Since the survival of children with NB has improved, a longer follow-up of their renal function in needed.

[Measurement of renal function in children]

Assessment of renal function in children raises several difficulties concerning technical and analytical aspects. Renal function parameters are influenced by both age and renal failure. Inulin clearance is the standard method to measure glomerular filtration rate, but it cannot be routinely used. Among other methods, plasma creatinine determination is not reliable to evaluate the level of renal function or to follow the course of renal diseases. Creatinine clearance estimated from calculations such as Schwartz formula does not provide an accurate estimation of the glomerular filtration rate. More precise estimate can be obtained from endogenous creatinine clearance, providing that the measurement is performed accurately. In this paper the authors review these factors and report personal data obtained from 500 children who underwent renal function investigation.

Effects of lisinopril on stress-induced peak blood pressure and sodium excretion: a double-blind controlled study

A stress test was performed before (S1) and after a 1-month treatment period (S2) in patients with essential hypertension, randomly allocated to receive either an angiotensin-converting enzyme inhibitor (ACEI), lisinopril (n = 10), or placebo (n = 10). The two groups were similar with regard to systolic and diastolic blood pressure (SBP, DBP), body weight, renal function, and 24-h sodium excretion. At S1, stress induced a significant increase in SBP of 18 +/- 9 mm Hg and in DBP of 10 +/- 6 mm Hg and a significant reduction in sodium excretion from 258 +/- 105 to 204 +/- 72 mumol/min. Stress-induced sympathetic stimulation was assessed by a significant increase in urinary norepinephrine (NE) excretion from 21 +/- 10 to 26 +/- 10 micrograms/g creatinine. One-month treatment by placebo did not change stress-induced BP reactivity, sodium retention, or urinary NE excretion. In the lisinopril group, rest and stress BP were significantly reduced by the treatment. Stress-induced sodium retention was higher after 1-month placebo treatment (72 +/- 78 vs 48 +/- 67 mumol/min), whereas this retention was significantly reduced by lisinopril (13 +/- 27 vs 69 +/- 60 mumol/min).

Outcome of cadaver kidney transplantation in small children

Small children have often been reported to have poor outcome after kidney transplantation (KT). Recent reports from North America have shown that the use of living-related donors improves patient and graft survival. We report the experience in one centre of primary cadaveric KT using sequential immunosuppression in nine children aged 8-30 months and weighing 5.4-9.8 kg; donors were 0.7-12.3 years old. Four patients had pre-emptive KT and the other five were on peritoneal dialysis; the mean +/- SD waiting time was 2.0 +/- 2.4 months. Perioperative care has been published previously. The surgical approach was intraperitoneal if the aorta and vena cava were used (n = 7) and extraperitoneal for common iliac vessels anastomosis (n = 2); the duration of surgery was 3.5 +/- 0.9 h and the time for vascular anastomosis was 32 +/- 6 min. The recipients received ATG, azathioprine, prednisone and delayed administration of cyclosporin A. The patients were followed for 12-98 (median 41) months and showed good graft function (inulin clearance 63-100 ml/min/1.73 m2); only one child with recurrent haemolytic uraemic syndrome lost his graft three months post-transplantation and died after he had received a second graft. None of the recipients required post-transplant dialysis; arterial hypertension involved four children and was related to graft artery stenosis in two. Growth improved by 0.24 +/- 0.48 SD score of height per year.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal concentrating capacity test by desmopressin in children: intranasal or intravenous route?

Intranasal administration of desmopressin (dDAVP) is frequently used to test renal concentrating capacity in children. However, the bioavailability of intranasal dDAVP is about 10% and may be modified by nasal congestion. The study aimed to compare the efficacy of intranasal dDAVP with an equivalent dose of intravenous dDAVP for a renal concentrating capacity test in children. We studied 18 children aged 12.6 +/- 3.8 years weighing more than 20 kg in whom a dDAVP test was indicated as part of global renal function evaluation. Spray applicator (Minirin Spray) was used for intranasal administration (20-40 micrograms according to BW); the dose of intravenous dDAVP (Minirin IV) was reduced to 10% (2-4 micrograms according to BW). A randomized sequence was used for the first intranasal or intravenous dDAVP test; the second alternate test was repeated in the same children in a time interval ranging from 1 to 3 weeks. Osmolality of the urine (Uosm, mosm/kg) was determined before (T0), then 2 (T2) and 4 (T4) h after dDAVP administration. There was no significant difference in Uosm at T0 (intranasal = 480 +/- 212, intravenous = 443 +/- 168 mosm/kg), T2 (604 +/- 226 and 542 +/- 173 mosm/kg, respectively), and T4 (657 +/- 206 and 629 +/- 190 mosm/kg, respectively). There was an obvious correlation between intranasal and intravenous Uosm at T4 (r2 = 0.826; p = 0.001). Even if intravenous dDAVP is of theoretical interest, intranasal administration of dDAVP using a spray applicator can be considered as first-choice method for a renal concentrating capacity test in children weighing more than 20 kg.

Influence of the level of hydration on the renal response to a protein meal

Recent studies have suggested that the renal effects of high protein intake could be mediated, at least in part, by vasopressin and/or an increase in the urinary concentrating activity. The present study investigated the influence of the level of hydration, and hence of the activity of the concentrating process, on the renal response to an acute oral protein load. Clearance studies were performed before (Control) and during three hours after a protein meal (1.5 g/kg body wt protein as cooked meat) in ten healthy volunteers. This study was performed twice at a two to three week interval under either constant low (LowH) or high (HighH) hydration. In spite of the marked difference in initial diuresis (3.1 +/- 0.3 in LowH vs. 13.9 +/- 0.7 ml/min in HighH) and urine osmolality (501 +/- 42 in LowH vs. 99 +/- 3 mOsm/kg H2O in HighH), a similar relative decrease in urine flow rate was observed following the meal in both conditions. TcH2O increased progressively by 70% in LowH whereas CH2O decreased by 40% in HighH. Plasma vasopressin showed a progressive increase with time in LowH (from 1.10 +/- 0.26 in control, to 1.98 +/- 0.35 pg/ml at the third hour after the PM, P < 0.05) but not in HighH (0.53 +/- 0.09 to 0.70 +/- 0.17 pg/ml). Glomerular filtration rate (inulin clearance) increased significantly on the second post-prandial hour under LowH but not under HighH. Excretions rates of Na, Cl, K, and urea increased after the meal, however, not to the same extent nor with the same time course in the two conditions. Significant positive correlations were observed between GFR and TcH2O, urine osmolality, or the ratio of urine-to-plasma urea concentrations in LowH. These results suggest that the protein-induced hyperfiltration is partially blunted by a high water intake, and hence is dependent, directly or indirectly, on the urine concentrating activity.

Acute renal failure with preserved renal plasma flow induced by cancer immunotherapy

Adoptive immunotherapy in patients with advanced cancer produces significant regression of metastatic disease in selected patients, but it is complicated by severe side effects. Prevention of these complications is still limited because their precise mechanisms remain unknown. For this reason we have investigated renal function and hemodynamic parameters in 16 patients with renal cell carcinoma before and during treatment with a combination of high doses of both recombinant interleukin-2 (rIL2) and recombinant alpha-interferon. After patients had received three injections of combined immunotherapy, there was a decrease in mean blood pressure (-20%), glomerular filtration rate (-25%), urine output (-50%), and fractional sodium excretion (-0.8%). This was associated with an increase in heart rate (+30%), plasma creatinine level (+30%), fractional potassium excretion (+14%) and microalbuminuria (+130%). However, renal plasma flow remained constant. The increment in microalbuminuria may reflect an alteration of glomerular capillary permeability. The reduction in GFR may be accounted either for a decrease in efferent to afferent arteriolar resistance ratio, leading to a decrease in glomerular capillary pressure, or for a decrease in ultrafiltration coefficient, or both. Nonsteroidal antiinflammatory drugs, such as ketoprofen, used to minimize side effects, could considerably worsen renal function and should be avoided in patients treated by rIL2. Our results bring new insights into the pathogenesis of functional acute renal failure and provide a rational basis for the use of vasopressors in the treatment of cytokine-induced acute renal failure.

Microalbuminuria is acutely increased during anesthesia and surgery

Microalbuminuria is known to increase in various diseases with potential repercussion on the kidneys and indicates an increase in glomerular intracapillary pressure or changes in permeability characteristics. In this study, we measured whether albumin excretion is affected in patients undergoing anesthesia and surgery, which are both known to induce dramatic changes in renal function and in the release of vasoactive substances such as catecholamines, vasopressin, angiotensin, and prostaglandins. Seven patients with normal renal function and physiological microalbuminuria prior to surgery were studied. Urine samples were collected before anesthesia, just before the beginning of surgery, and thereafter 30 min following incision, and 30 min after the end of surgery. Anesthesia induced a significant increase in microalbuminuria, which further increased during surgery. After the end of surgical procedure, microalbuminuria decreased but remained significantly higher than control. This phenomenon may be due to an increase in intracapillary glomerular pressure and/or an alteration in glomerular permeability induced by a direct effect of drugs, or to the action of vasoactive substances on the glomerular structure.