Pierre Robitaille

LONG-TERM FOLLOW-UP OF PATIENTS WHO UNDERWENT UNILATERAL NEPHRECTOMY IN CHILDHOOD

The long-term damaging potential of remnant nephron hyperperfusion was investigated in patients who had undergone unilateral nephrectomy in childhood. 27 such patients were examined after a mean of 23.3 years postnephrectomy. The average creatinine clearance was 83.9 +/- 16.5 ml/min/1.73 m2 or 74.3% of that in healthy controls with two kidneys; it was a value similar to that reported 3 to 6 months postnephrectomy in kidney donors. Age at the time of nephrectomy, duration of follow-up, or sex had no influence on the residual creatinine clearance. None of these patients had clinically important hypertension or proteinuria. Since so little evidence of kidney damage could be documented after such a long observation period, hyperperfusion would seem to be seldom of clinical importance in man unless other factors were present.

Circulating inflammatory cytokine levels in hemolytic uremic syndrome

Abstract Experimental data suggest that the host’s inflammatory response is involved in the pathophysiology of verotoxin-producing Escherichia coli (VTEC)-associated hemolytic uremic syndrome (HUS). We compared the circulating levels of pro- [interleukin (IL)-6, IL-8] and anti-inflammatory [IL-10 and IL-1 receptor antagonist (Ra)] mediators on enrollment among children with HUS due to E. coli O157:H7, according to the severity of renal dysfunction. The latter was evaluated by the occurrence of oligoanuria, the requirement for dialysis, and a glomerular filtration rate (GFR) ≤80 ml/min per 1.73 m2 measured 1 year later. Increased levels of IL-6 (P<0.0001), IL-10 (P<0.0001), and IL-1Ra (P<0.07) were found among patients with HUS compared with normal controls. Children with severe renal dysfunction also had tenfold increased levels of IL-6 and higher concentrations of IL-10 and IL-1Ra. Both the IL-6/IL-10 (4.9±8.3 vs. 0.5±0.4, P=0.01) and the IL-6/IL-1Ra ratios (0.10±0.20 vs. 0.01±0.01, P=0.04) were significantly increased. GFR correlated well with IL-6 levels, IL-6/IL-10 and IL-6/IL-1Ra ratios. Our data demonstrate that the inflammatory response of the host is associated with the severity of renal dysfunction during classic HUS. An imbalance between the pro- and the anti-inflammatory responses may be involved in the pathophysiology of VTEC-associated HUS.

Inflammatory mediators in Escherichia coli O157:H7 hemorrhagic colitis and hemolytic-uremic syndrome.

BACKGROUND Recent experimental data suggest that the inflammatory response of the host to verotoxin and/or lipopolysaccharides of Escherichia coli is involved in the pathophysiology of verotoxin-producing E. coli (VTEC) infections. METHODS We measured the circulating concentrations of cytokines [TNF-alpha, interleukin (IL)-1-beta, IL-1 receptor antagonist (Ra), IL-6, IL-8, IL-10] and soluble leukocyte adhesion molecules (L-selectin, P-selectin, E-selectin, intracellular cell adhesion molecule-1, vascular cell adhesion molecule-1) by sandwich enzyme-linked immunosorbent assay among (1) normal controls (n = 12), (2) disease controls with hemorrhagic colitis (HC) not associated with VTEC infections (n = 57), (3) patients with uncomplicated HC caused by E. coli O157:H7 (n = 30), and (4) children with hemolytic-uremic syndrome (HUS) (n = 28). Patients with HUS were matched with children who presented an uncomplicated HC caused by E. coli O157:H7 for the time interval elapsed between the onset of HC and that of blood sample collection. RESULTS Concentrations of TNF-alpha and IL-1-beta were undetectable. Children with HUS were characterized by increased amounts of IL-6 and IL-8, lower values of soluble L-selectin as well as increased levels of IL-10 and IL-1Ra. The circulating concentrations of IL-1Ra were higher among children with O157:H7 HC who subsequently developed HUS. CONCLUSIONS Increased pro- and antiinflammatory cytokine responses are produced by the host during the development of HUS among children with VTEC infections. Further studies are needed to determine their relative contribution to the pathophysiology of classic HUS.

Plasma homocysteine concentration in children with chronic renal failure

Abstract. Hyperhomocysteinemia, a risk factor for vascular disease, is commonly found in adult patients with end-stage renal disease. Major determinants of elevated plasma homocysteine levels in these patients include deficiencies in folate and vitamin B12, methylenetetrahydrofolate reductase (MTHFR) genotype and renal function. Little information is available for children with chronic renal failure (CRF). The prevalence and the factors that affect plasma homocysteine concentration were determined in children. Twenty-nine children with various degrees of CRF (15 were dialyzed, 14 were not dialyzed) were compared with 57 age- and sex-matched healthy children. Homocysteine concentrations were higher in patients than controls (17.3 µmol/l vs 6.8 µmol/l, P<0.0001) and hyperhomocysteinemia (>95th percentile for controls: 14.0 µmol/l) was seen in 62.0% of patients and 5.2% of controls. Folate concentrations were lower in patients (9.9 nmol/l) than controls (13.5 nmol/l), P<0.01. Vitamin B12 was similar in patients (322 pmol/l) and controls (284 pmol/l). Dialyzed patients have a higher prevalence of hyperhomocysteinemia than nondialyzed patients (87% vs 35%). Dialyzed patients with MTHFR mutation have higher plasma homocysteine (28.5 µmol/l) than nondialyzed patients with the mutation (10.7 µmol/l), P<0.002. In our study, differences between controls and patients in plasma homocysteine concentrations are observed when age is greater then 92 months, folate less than 21.6 nmol/l and vitamin B12 less than 522 pmol/l.Our study shows that hyperhomocysteinemia is common in children with CRF and is associated with low folate and normal vitamin B12 status, compared to normal children. Among the patients, the dialyzed patients with the MTHFR mutation are particularly at risk for hyperhomocysteinemia. Further studies are needed to investigate therapeutic interventions and the potential link with vascular complications in these patients.

Dicarboxylic aminoaciduria: an inborn error of amino acid conservation.

A 38-month-old apparently healthy male has been followed for three years because of a massive glutamic and aspartic aminoaciduria detected shortly after birth in a neonatal screening program. Amino acid clearance studies revealed the presence of renal wastage of dicarboxylic amino acids. Intestinal transport and in vitro oxidation of dicarboxylic amino acids were found to be intact. Clinical and metabolic data obtained on a previously described patient and the present case suggest that some patients with dicarboxylic aminoaciduria might have a selective renal conservation defect without clinical abnormalities, whereas others might demonstrate an additional defect in intestinal transport associated with fasting hypoglycemia.

Clinical efficacy of levamisole in the treatment of primary nephrosis in children

The purpose of the study was to evaluate the efficacy and the toxicity of levamisole given for 1 year to 16 children suffering from minimal change primary nephrosis who were relapsing frequently. The overall results showed that under levamisole the relapse rate decreased by 55% and the steroid requirements by 50%. After cessation of levamisole administration, most children (11/16) relapsed again. A second course of levamisole treatment reduced the relapse rate significantly once again. At the dosage of 2.5 mg/kg given every other day for 1 year or more, no side effects of levamisole were observed. It is concluded that levamisole does not cure nephrosis but reduces the incidence of relapses for the period it is administered. It also reduces the steroid requirements without any important side effects.

Orchitis mimicking testicular torsion in Henoch-Schönlein's purpura.

Henoch-Schönleins purpura is a systemic vasculitis involving mainly skin, joints, intestine and kidney. We report on 2 patients who presented with clinical signs and symptoms suggestive of testicular torsion. In 1 case purpuric areas after leg cast removal indicated a diagnosis of Henoch-Schöleins purpura. Surgical exploration of the other case revealed congestion of the hydatid of Morgagni, which was followed by typical systemic manifestations of Henoch-Schönleins purpura. These and another case indicate that orchitis accompanying Henoch-Schönleins purpura may mimic testicular torsion.

Hyperlipidemic profiles during remission in childhood idiopathic nephrotic syndrome

Hyperlipidemia, an important characteristic of idiopathic nephrotic syndrome in children (NS), is usually observed during the active phase of the disease and disappears with the resolution of the proteinuria. However, persisting lipid anomalies during remission have been reported in a few studies and raise the question of the later development of atherosclerosis. Plasma lipid profiles in 25 children with NS at remission, with or without active prednisone treatment, were compared with those of an age-matched population. The results indicate that plasma total and LDL-cholesterol levels were above the 95(th) percentile for age and sex in 12 of the 25 patients (48%) with 7 of them having apolipoprotein B and triglyceride concentrations above the 95(th) percentile. Moreover, frequently relapsing children were more likely to have abnormal lipid profile during the remission. We conclude that close monitoring of lipid levels during the remission of the NS especially in those with frequent relapses, is necessary to select the high-risk patients.

Kidney Transplantation in Uremic Children with Cystinosis

10 children underwent cadaveric renal transplantation between the ages of 8.0 and 12.5 years for uremia secondary to infantile cystinosis. 6 children are doing well 6-62 months after-transplantation. 3 of the 4 other recipients required a second graft and eventually died of uremia or fulminant viral encephalitis, the other lost her first graft due to accelerated acute rejection and is now on maintenance hemodialysis. No further systemic complications of cystinosis have been observed in the patients with functioning grafts. Our experience confirms that kidney transplantation is the treatment of choice for uremic children with infantile cystinosis.

Study of psychosocial parameters related to the survival rate of renal transplantation in children

Abstract. The purpose of the present study was to assess the effect of intelligence, schooling, psychomotor, emotional, and social status on renal graft survival in children. Sixty-two cadaver renal transplant recipients were evaluated retrospectively and the influence of sex, age, weight, and the use of cyclosporin A (CyA) on the success rate of the graft from 1 to 5 years later was analyzed. Psychological and social scores were devised and included as factors predictive of survival of the graft. Univariate analysis showed that the following variables predicted renal graft survival: the use of CyA (P = 0.0002), pre-transplant dialysis (P = 0.04), weight at the time of transplantation (P = 0.072), and psychological scores (P = 0.064). Association analysis demonstrated that pre-transplantation dialysis was only a chance association and therefore the parameter was discarded. Multivariate analysis showed that the predictive parameters were the use of CyA, sex, weight in kilograms, and the psychological score. An equation was then derived from variables that predict the probability that a specific patient’s graft will survive more than t months. This equation is the estimated survival distribution function and is as follow: S (t) = Exp {–Exp[–(0.8882x1–1.827x2+0.037x3–0.1746x4)+ln t–4.7862]} where S (t) = the survival at t months post transplantation, x1 = sex (male 1, female 2), x2 = CyA (yes 1, no 2), x3 = weight in kilograms, and x4 = psychological score. The major impact of psychological factors on renal graft survival was surprising.