Population pharmacokinetics of mycophenolic acid in kidney transplant pediatric and adolescent patients.

Current data on mycophenolate mofetil (MMF) suggest that there is a pharmacokinetic/pharmacodynamic relationship between the mycophenolic acid (MPA) area under the curve (AUC) during treatment and both the risk of acute rejection and the occurrence of side effects. The aim of this study was to characterize the population pharmacokinetics of MPA in kidney transplant patients between the ages of 2 and 21 years and to propose a limited sampling strategy to estimate individual MPA AUCs. Forty-one patients received long-term oral MMF continuous therapy as part of a triple immunosuppressive regimen, which also included cyclosporine or tacrolimus (n=3) and corticosteroids. Therapy was initiated at a dose of 600 mg/m twice daily. The population parameters were calculated from an initial group of 32 patients. The data were analyzed by nonlinear mixed-effect modeling using a 2-compartment structural model with first-order absorption and a lag time. The interindividual variability in the initial volume of distribution was partially explained by the fact that this parameter was weight-dependent. Fifteen concentration-time profiles from 13 patients were used to evaluate the predictive performance of the Bayesian approach and to devise a limited sampling strategy. The protocol, involving two sampling times, 1 and 4 hours after oral administration, allows the precise and accurate determination of MPA AUCs (bias -0.9 microg.h/mL; precision 6.02 microg.h/mL). The results of this study combine the relationships between the pharmacokinetic parameters of MPA and patient covariates, which may be useful for dose adjustment, with a convenient sampling procedure that may aid in optimizing pediatric patient care.

Initial presentation of childhood-onset systemic lupus erythematosus: a French multicenter study.

OBJECTIVE: To describe the clinical and laboratory manifestations of childhood-onset systemic lupus erythematosus (SLE) at presentation. STUDY DESIGN: This retrospective French multicenter study involved 155 patients in whom SLE developed before the age of 16 years. Mean patient age at onset was 11.5 +/- 2.5 years (range, 1.5-16 years). The female to male ratio was 4.5. RESULTS: The most common initial manifestations were hematologic (72%), cutaneous (70%), musculoskeletal (64%), renal (50%), and fever (58%). Thirty-two percent of children had atypical symptoms, mainly including abdominal involvement in 26 patients, which lead to negative laparotomy results for presumed appendicitis. Severe renal, neurologic, hematologic, abdominal, cardiac, pulmonary, thrombotic, and/or cutaneous manifestations occurred within the first month after the diagnosis in 40% of patients. The mean erythrocyte sedimentation rate was 72 +/- 29 mm/h, and the mean C-reactive protein value 22 +/- 21 mg/L. Antinuclear antibodies an, anti-double stranded DNA antibodies, and low C3 or C4 level were retrieved in 97%, 93%, and 78 % of patients, respectively. CONCLUSION: Initial manifestations of childhood-onset SLE are diverse and often severe. The diagnosis of SLE should be promptly considered in any febrile adolescent with unexplained organ involvement, especially when associated with an increased erythrocyte sedimentation rate.

[Revised prevalence of afa+ Escherichia coli strains in acute pyelonephritis of children]. / Révision de la prévalence des souches afa+ dans les Escherichia coli responsables de pyélonéphrites aiguës de l'enfant.

Two hundred E. coli strains isolated from children with pyelonephritis were investigated for the presence of six virulence factors. The used primers amplified adhesin pap and sfa, toxin haemolysin (hly) and cytotoxic necrotizing factor 1 (cnf1) and aerobactin (aer). For afimbrial adhesin, the previously used set of primers could not allow to detect the newly reported afa operons (Le Bouguenec et al., 2001). With a new set of primers specific for the afa operon family the prevalence of afa+ strains increased from 3.5% to 13.5%. Combinations of three or more factors in a same strain were found in 48.5%. Thirty two different urovirulent genotypes were observed; two strains contained the six studied factors.

[Value of MR imaging of the fetal kidney]. / Apport de l'IRM dans l'étude du rein foetal.

Sonography is the imaging modality of choice for initial evaluation of the fetus. However, the role of MR imaging for fetal evaluation is expanding. Based on a review of seven cases, the role of MRI to further characterize renal abnormalities detected at US, especially hyperechoic kidneys, is demonstrated.

[Terminal and pre-terminal chronic renal insufficiency in newborns in French neonatal intensive care units: survey of the French pediatric nephrologic society of resuscitation and emergency]. / Insuffisance rénale chronique terminale et préterminale du nouveau-né dans les services de réanimation français: enquête de la Société de néphrologie pédiatrique auprès du Groupe francophone de réanimation et d'urgences pédiatriques.

OBJECTIVES: The aim of this study was to describe the intensive care unit neonatologists' attitudes about a neonate with terminal or pre-terminal renal failure. METHODS: A questionnaire was sent to all French neonatal intensive care units. Physicians were asked to describe their attitude about neonatal chronic renal failure (Would you agree with dialysis and graft for these children?). Physicians were also presented with two clinical observations involving neonates with varying degrees of renal insufficiency and a complicating comorbidity, including neurological abnormality or socioeconomic circumstances. RESULTS: Responses were obtained from 92% of the university neonatal care units. The will to take care of a neonate with end-stage renal failure till the renal graft, varied greatly from a centre to another one. Three (9%) university-teams said they had a strong will to bring the baby from the neonatal period to the time of renal graft. Eleven other centres (32%) did not have any will for accompanying the baby till the renal graft. Eight centres (24%) would be rather favourable to the idea of dialysis and graft, and 12 others (35%) would be rather unfavourable. CONCLUSION: The results of this study show great differences between French neonatologists when they are faced to newborns with end stage renal failure. Ethical, medical and organisational difficulties are matters of controversy. The epidemiological impact of the perinatal discussion could be a 20% variation of all the renal grafts in children.

PAX2 mutations in renal-coloboma syndrome: mutational hotspot and germline mosaicism.

The renal-coloboma syndrome (RCS, MIM 120330) is an autosomal dominant disorder caused by PAX2 gene mutations. We screened the entire coding sequence of the PAX2 gene for mutations in nine patients with RCS. We found five heterozygous PAX2 gene mutations: a dinucleotide insertion (2G) at position 619 in one sporadic RCS case, a single nucleotide insertion (619 + G) in three unrelated cases, and a single nucleotide deletion in a familial case. In this familial case, three affected sibs showed a striking ocular phenotypic variability. Each of the sibs carried a 619insG mutation, whilst unaffected parents did not, suggesting the presence of germline mosaicism. Interestingly, the 619insG mutation has been previously reported in several patients and is also responsible for the Pax21Neu mouse mutant, an animal model of human RCS. This study confirms the critical role of the PAX2 gene in human renal and ocular development. In addition, it emphasises the high variability of ocular defects associated with PAX2 mutations ranging from subtle optic disc anomalies to microphthalmia. Finally, the presence of PAX2 germline mosaicism highlights the difficulties associated with genetic counselling for PAX2 mutations.

Oligotyping for HLA-DQA, -DQB, and -DPB in idiopathic nephrotic syndrome.

Associations of human leukocyte antigens (HLA) with the idiopathic nephrotic syndrome (NS) have mainly been described for alleles of the HLA-DR locus. In the present study the polymorphism of HLA-DQ and -DP at the molecular level was investigated in 167 children with NS (129 steroid-sensitive) using the polymerase chain reaction and sequence-specific oligonucleotides in a French and a German cohort. HLA-DR typing was also performed by classical serology. In steroid-sensitive patients we observed an increased frequency of the alleles HLA-DQA1*0201 and -DQB1*0201 in both populations with relative risks ranging from 3.8 to 8.5 (Pb < 0.01 to Pb < 0.00001 after Bonferoni's correction). In contrast, the frequency of HLA-DQA1*0102 and DQB1*0602 was significantly decreased. In children with frequent relapses the HLA associations were generally more pronounced than in those with infrequent or no relapses. Applying logistic regression analysis, a nephrotic child bearing DQA1*0201 or DR7 was five times more likely to be in the steroid-sensitive group of patients than in the steroid-resistant group compared with nephrotic children not bearing one of these alleles. These HLA alleles therefore seem to be useful indicators of a steroid-sensitive frequently relapsing course of NS. No associations with DPB alleles were observed, which narrows the region genetically involved in the disease susceptibility to the DR-DQ region. Steroid-resistant NS was not associated with HLA.

Risk factors for chronic rejection in pediatric renal allograft recipients.

To determine the risk factors predictive of graft loss from chronic rejection in pediatric renal allograft recipients, we reviewed the collaborative study database of the Société de Néphrologie Pédiatrique which registered 314 grafts from January 1987 to December 1991. Of the 289 grafts analyzed, 71 failed during follow-up, chronic rejection being the most common cause of graft loss (35%). The clinical features of the chronic rejection group (n = 25) were compared with those of the group without failure (n = 218). The variables tested by monovariate analysis were cyclosporine dose at 1 year, donor type, donor and recipient age, and acute rejection episodes. The incidence of graft loss due to chronic rejection was 4% (4/109) in patients who had no acute rejection and 16% (21/134) in those with at least one acute rejection episode (P = 0.002). Donor age (< or = 5 years) was a risk factor for chronic rejection (P = 0.024). Recipient age and donor type were not significantly different between the chronic rejection group and the control group. Using time-dependent covariates, the risk factors were an acute rejection episode (P = 0.003) and low cyclosporine doses at 1 year (P = 0.02). We conclude that acute rejection and low cyclosporine doses in these pediatric patients were risk factors for graft loss due to chronic rejection.

Clinical implications from studies of HLA antigens in idiopathic nephrotic syndrome in children.

HLA class I and II antigen frequencies were determined in two large cohorts of children with idiopathic nephrotic syndrome (NS) from Southwest France (n = 199) and Southwest Germany (n = 152) and compared with unrelated healthy individuals from the same geographical areas. Strength of HLA association was expressed by the relative risk (RR) estimated by Odd's ratio. We examined 105 steroid-resistant and 242 steroid-sensitive NS patients who were subdivided in non-relapsers, infrequent relapsers and frequent relapsers or steroid-dependent patients. In steroid-sensitive patients significant associations were found with HLA-DR7 (RR 5.1 in French, 3.2 in Germans), -DQ2 (RR 4.7/2.3) and with the phenotypic combination HLA-DR3/DR7 (RR 5.6/7.7). Significant negative associations were encountered with HLA-DR2, -DR6 and -DQ1. The associations were stronger in frequent relapsers/steroid-dependent patients than in infrequent relapsers and were not significant in non-relapsers. In steroid-resistant patients the only significant association found was with the combined occurrence of HLA-DR3/DR7. We propose that in childhood NS tissue typing for selected HLA class II antigens is helpful in prediciting the clinical course.

DQCAR microsatellite polymorphisms in three selected HLA class II-associated diseases.

DQCAR is a very polymorphic CA repeat microsatellite located between the HLA DQA1 and DQB1 gene. Previous studies have shown that specific DQCAR alleles are in tight linkage disequilibrium with known HLA DR-DQ haplotypes. Of special interest was the fact that haplotypes containing long CA repeat alleles (DQCAR > 111) were generally more polymorphic within and across ethnic groups. In these latter cases, several DQCAR alleles were found even in haplotypes containing the same flanking DQA1 and DQB1 alleles. In this work, three HLA class II associated diseases were studied using the DQCAR microsatellite. The aim of this study was to test if DQCAR typing could distinguish haplotypes with the same DRB1, DQA1 and DQB1 alleles in control and affected individuals. To do so, patients with selected HLA DR-DQ susceptibility haplotypes were compared with HLA DR and DQ matched controls. This included: Norwegian subjects with Celiac disease and the HLA DRB1*0301, DQA1*05011, DQB1*02 haplotype; Japanese subjects with Type 1 (insulin-dependent) Diabetes Mellitus and the HLA DRB1*0405, DQA1*0302, DQB1*0401 haplotype; and French patients with corticosensitive Idiopathic Nephrotic Syndrome and the HLA DRB1*0701, DQA1*0201, DQB1*0202 haplotype. These specific haplotypes were selected from our earlier work to include one haplotype bearing a short DQCAR allele (celiac disease and DR3,DQ2-DQCAR99) and two haplotypes bearing long DQCAR alleles (Diabetes Mellitus and DR4,DQ4-DQCAR 113 or 115 Idiopathic Nephrotic syndrome and DR7,DQ2-DQCAR 111-121). Additional DQCAR diversity was found in both control and patients bearing haplotypes with long CA repeat alleles. The results indicate that DQCAR typing did not improve specificity in combination with high resolution DNA HLA typing as a marker for these three disorders.

HLA class II associations with idiopathic nephrotic syndrome in children.

The occasional familial occurrence of idiopathic nephrotic syndrome (NS) points to a genetic predisposition. Reports on associations with certain HLA class II antigens support this hypothesis. In order to define the immunogenetic background of NS more precisely, HLA class II allele frequencies in 161 children with NS were studied by restriction fragment length polymorphism (RFLP) typing. The patient cohorts consisted of 87 children from Southwest-France and 74 from Southwest-Germany. The control group consisted of 118 French and 101 German unrelated individuals from the same geographical areas. HLA alleles were defined in patients with steroid-sensitive (SS) and steroid-resistant (SR) NS and in controls. RFLP typing revealed that the previously reported association between SSNS and HLA-DR7 is confined to the RFLP split 7.1 (DRB1*07) with a combined relative risk (RRcomb) of 6.2. HLA-DQB typing showed an increased frequency of the allele DQB2b (DQB1*0201) (RRcomb = 7.8). HLA-DQA typing showed an association of SSNS with DQA3 (DQA1*0201,0301,0302) (RRcomb = 4.1). The highest RR (16.5) for SSNS was found in German patients who carried the two DRB1 specificities 17.1 (DRB1*0301) and 7.1 (DRB1*07). All associations were stronger in SS patients with frequent relapses or steroid dependency than in non- or infrequent relapsers. SR patients exhibited no significant associations with HLA class II alleles.

[Fetal and neonatal effects of maternal treatment with angiotensin converting enzyme inhibitor]. / Effets foetaux et néonatals d'un traitement maternel par inhibiteur de l'enzyme de conversion de l'angiotensine.

BACKGROUND. Exposure of pregnant women to angiotensin converting enzyme inhibitor may have side effects on the fetus or newborn, mainly oligoamnios and impaired renal function. CASE REPORT N zero 1. A 34 year-old woman was given enalapril from the onset of her pregnancy because of hypertension from the age of 18 years. Oligoamnios was diagnosed in the fetus on gestational week 28; enalapril was then replaced by nifedipine but this drug was badly tolerated so that the woman was again given enalapril 8 days later. The baby (1700 g) was born by cesarean section at gestational week 34 because of acute distress syndrome; he developed hypotension, anuria, generalized oedema and was placed in intensive care. Treatment included ventilation, sympathomimetic agents, and diuretics. An exchange-transfusion followed by peritoneal dialysis was performed a few hours later. Renal function returned to normal between the 3rd and 5th day. Unilateral kidney hypoplasia was diagnosed at the age of 2 years. CASE N zero 2. A 24 year-old woman was given enalapril at the third trimester of a twin pregnancy. Delivery was full term at 37 weeks. The first baby, a boy weighing 2610 g, suffered from hypoglycemia and vomiting followed by hypotension and oliguria that required exchange-transfusion and repeated peritoneal dialysis. This boy has developed moderate chronic renal failure and hypertension. The second baby, a girl weighing 2,165 g, suffered from respiratory distress syndrome followed by hypotension and oliguria, but her renal function returned to normal within a few days. CONCLUSIONS. The use of angiotension converting enzyme inhibitor by pregnant women places the fetus at severe risk: treatment with this type of drug should be stopped as soon as pregnancy is confirmed.

Deletion of the mitochondrial DNA in a case of de Toni-Debré-Fanconi syndrome and Pearson syndrome.

We report a patient with Pearson syndrome with failure to thrive, exocrine pancreas insufficiency, growth hormone deficiency and severe tubular dysfunction. The patient had no signs of liver involvement. Normal respiratory chain enzyme activity was found in the lymphocytes, but a mitochondrial DNA deletion was demonstrated in lymphocytes and in the kidney. Polymerase chain reaction amplification and sequence analysis revealed the presence of the 4,977 base pair "common" deletion in the mitochondrial genome. Our findings support the view that tubulopathies of unknown origin may be related to mitochondrial respiratory chain deficiency.