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Biomedical subjects

J J Robert

Publications and source records attributed to J J Robert.

At least 19 recordsLinked to original sources
PubMed2006

Genetic and epigenetic defects at the 6q24 imprinted locus in a cohort of 13 patients with transient neonatal diabetes: new hypothesis raised by the finding of a unique case with hemizygotic deletion in the critical region.

BACKGROUND: Transient neonatal diabetes (TND) is a rare form of diabetes usually present in the first few days after birth that resolves within 1 year but that has a tendency to recur later in life. It can be associated with chromosome 6 paternal uniparental disomy (UPD), paternal duplications or loss of maternal methylation at the 6q24 imprinted locus. OBJECTIVE: To report on a cohort of 13 sporadic TND cases, including five with birth defects (congenital abnormalities of heart, brain and bone) and eight without. RESULTS: The hallmarks of diabetes were similar in patients with or without 6q24 defects. The chromosome 6 abnormalities in our patients (n = 13) included 2 of 13 (approximately 15.4%) cases of paternal UPD6, 2 of 11 (approximately 18%) cases of complete and 3 of 11 (approximately 27%) cases of partial loss of the maternal methylation signature upstream of ZAC1-HYMAI imprinted genes in non-UPD cases, and 1 of 13 (approximately 7.7%) cases of hemizygotic deletion. CONCLUSION: The deletion was found in a patient with severe congenital abnormalities. This genetic lesion was not reported previously. The hypothesis of an effect on regulatory elements critical for imprinting and tissue-specific gene expression in early development by the deletion is raised. The data presented here may contribute to the diagnosis and the understanding of imprinting in the region.

Abnormalities, Multiple↗
PubMed2005

Cross-sectional study of care, socio-economic status and complications in young French patients with type 1 diabetes mellitus.

OBJECTIVES: To describe the present status of type 1 diabetes care in France and study the relations between clinical and socio-economic variables on one hand and disease management and prevalence of complications on the other hand. METHODS: A random sample of 365 French specialists in diabetes care performed a cross-sectional study and included consecutively 562 children aged 10-16 and 1691 adults aged 16-45, with more than 2 years of type 1 diabetes. The main outcome measures were the prevalence of complications (retinal, renal, lower-limb, cardiovascular, ketoacidosis); disease management parameters (blood pressure, HbA1c, daily number of insulin injections, frequency of visits to a specialist in diabetes, membership of a patient association); socio-economic status as a score, and treatments received. RESULTS: Retinal complications were rare in children (0.7%) and common in adults (28.3%). 10.2% children and 15.2% adults had micro- or macro-albuminuria, 4.7% adults had plasma creatinine >or=150 micromol/L. Only 15% children and 26% adults had HbA1c<7%, 86.2% children and 62.7% adults had blood pressure<130/85 mmHg; 58% children and 80% adults had at least 3 daily insulin injections. In adults, the risk of experiencing at least one complication was linked significantly with diabetes duration, HbA1c, and socio-economic status. Age, sex, type of insulin therapy, tobacco consumption, and blood pressure control were not significant parameters. Ketoacidosis in the preceding year was only linked with HbA1C and socio-economic status. CONCLUSION: Although this sample of patients had overall a fair socio-economic status and were followed-up by specialists of diabetes care, metabolic and blood pressure control were not optimal. The care of French type 1 diabetics could probably be improved by a stricter control of glycaemia and blood pressure, and an earlier use of intensive insulin treatment, with a particular focus on adolescents and patients with the lowest socio-economic status.

Adolescent↗
PubMed2004

Serum leptin level is a regulator of bone mass.

Leptin is a powerful inhibitor of bone formation in vivo. This antiosteogenic function involves leptin binding to its receptors on ventromedial hypothalamic neurons, the autonomous nervous system and beta-adrenergic receptors on osteoblasts. However, the mechanisms whereby leptin controls the function of ventromedial hypothalamic antiosteogenic neurons remain unclear. In this study, we compared the ability of leptin to regulate body weight and bone mass and show that leptin antiosteogenic and anorexigenic functions are affected by similar amounts of leptin. Using a knock-in of LacZ in the leptin locus, we failed to detect any leptin synthesis in the central nervous system. However, increasing serum leptin level, even dramatically, reduced bone mass. Conversely, reducing serum-free leptin level by overexpressing a soluble receptor for leptin increased bone mass. Congruent with these results, the high bone mass of lipodystrophic mice could be corrected by restoring serum leptin level, suggesting that leptin is an adipocyte product both necessary and sufficient to control bone mass. Consistent with the high bone mass phenotype of lipodystrophic mice, we observed an advanced bone age, an indirect reflection of premature bone formation, in lipodystrophic patients. Taken together, these results indicate that adipocyte-derived circulating leptin is a determinant of bone formation and suggests that leptin antiosteogenic function is conserved in vertebrates.

Animals↗
PubMed2003

[Blood glucose monitoring in the management of type 1 diabetes in childhood].

In the last twenty years, blood glucose self-monitoring has attained a nearly optimal level, with reliability, easiness, quickness and safety, which makes it tolerable to a greater number of patients and allows young diabetics to make more easily something which is mandatory to the management of type 1 diabetes. The principles of treatment are identical in children, adolescents and adults. However, many patients experience difficulties in applying the ideal therapeutic model. This must be particularly taken into account in children, who are in a stage of full intellectual and psychological development. Inappropriate demands can drive them to failure and go against the main objective at this period of life, which is education. Reference documents help pediatricians to the daily practice of home blood glucose monitoring and, more generally, management of childhood diabetes: ISPAD Consensus Guidelines (ISPAD=International Society for Pediatric and Adolescent Diabetes), which has been translated in French, and Cahiers de l'AJD (AJD Note books), for educating new patients. Blood glucose monitoring is recommended: to evaluate the glycemic response to the effect of insulin; to confirm hypoglycemia; to prevent hyperglycemia in case of disease; in case of physical exercise. The frequency of home blood glucose monitoring should be individualized, depending on the acceptability for the young patients and the insulin therapeutic regimen.

Adolescent↗
PubMed2002

[Micro-angiopathic and psychological risk in children and adolescents with type 1 diabetes].

OBJECTIVE: Evaluate the correlation between psychopathological disorders in type 1 insulin-dependent diabetic (IDD) children and adolescents and the occurrence of micro-angiopathic complications. METHODS: Two hundred and five IDD children (104 girls and 101 boys with a mean age of 13.4 +/- 3.5 years on inclusion) were longitudinally monitored between 1994 and 2000. Somatic complications were systematically searched for during a yearly control visit to the day hospital. Psychiatric disorders had been assessed initially by self-administered questionnaires filled-in by the children (Spielberger's STAIC-Trait for anxiety, CESD for depression and Child-EAT for eating habits), by the parents (CBCL, CPRS or GHQ-28) or the principle teachers (CTRS) and diagnostic screening of psychopathological disorders every year. RESULTS: More than 140% of the IDD children (n = 86) were diagnosed DSM-IV, with predominant anxiety (n = 41), during the longitudinal evaluation. Positive screening was significantly associated with higher psychopathological scores before inclusion in the study, with children considered more perturbed by the parents, teachers and the children themselves and mothers who considered themselves more perturbed (GHQ-28 mean 5.6 +/- 7.5 vs. 3.5 +/- 4.8; t = 2.211 p = 0.028). These children were less compliant. Disorders were associated with metabolic imbalance, measured by HbA1c, overweight and an excess of micro-angiopathic, particularly retinopathic, complications. CONCLUSION: Our results show the frequency of mental disorders in IDD children, the importance of the parents' psychopathology and its association with increased somatic risk. The nature of this relationship requires clarification and the incidence of prevention measures targeted on the psychological problems. The interest of associating a paedopsychiatric element in the therapeutic management of these patients and their families is emphasized.

Adolescent↗
PubMed2002

Efficacy of Humalog injections before an afternoon meal and their acceptance by children and adolescents with type 1 diabetes.

AIMS: To evaluate the acceptability and efficacy of an injection of insulin lispro, before an afternoon meal. METHODS: The subjects, 43 patients with Type 1 diabetes, 16 boys and 27 girls, aged 12.4 +/- 2.4 years, were randomly assigned to the treatment (n = 20) or the untreated control group (n = 23). The treatment was an injection of insulin lispro immediately before the afternoon meal. The control group had no injection. The treatment and the control group consumed identical types of meals for 2 months. The mean before-dinner blood glucose was measured during the last 2 weeks of the study. RESULTS: Injection of insulin lispro resulted in a significant reduction in the before-dinner blood glucose compared with the untreated control group (10.4 +/- 3.8 mmol/l vs. 14.7 +/- 3.9 mmol/l, respectively). The number of days on which the blood glucose was > 10 mmol/l was reduced by half in the insulin lispro group. The difference in HbA1c between baseline and endpoint differed slightly but significantly between the two groups, in boys. Treated patients ate the meal less frequently (11.4 +/- 3.0 times per 15 days) than the control patients (14.4 +/- 0.6 times per 15 days) and injected themselves with insulin 8.9 +/- 3.6 times per 15 days. The HbA1c increased significantly with the number of meals taken without injection. There was no statistically significant difference in the frequency of hypoglycaemia or changes in weight between the two groups. CONCLUSIONS: We conclude that an injection of insulin lispro before the afternoon meal can effectively lower the before-dinner blood glucose, and in boys also lowers the HbA1c. Patients were satisfied with the lower blood glucose before dinner, and did not find the insulin lispro injection difficult. However, compliance with the protocol procedures decreased during a subsequent 6-month period.

Blood Glucose↗
PubMed2002

Genotype-phenotype relationships in Berardinelli-Seip congenital lipodystrophy.

Generalised lipodystrophy of the Berardinelli-Seip type (BSCL) is a rare autosomal recessive human disorder with severe adverse metabolic consequences. A gene on chromosome 9 (BSCL1) has recently been identified, predominantly in African-American families. More recently, mutations in a previously undescribed gene of unknown function (BSCL2) on chromosome 11, termed seipin, have been found to be responsible for this disorder in a number of European and Middle Eastern families. We have studied the genotype/phenotype relationships in 70 affected subjects from 44 apparently unrelated pedigrees of diverse ethnic origin. In all subjects, hepatic dysfunction, hyperlipidaemia, diabetes mellitus, and hypertrophic cardiomyopathy were significant contributors to morbidity with no clear differences in their prevalence between subjects with BSCL1 or BSCL2 and those with evidence against cosegregation with either chromosome 9 or 11 (designated BSCLX). BSCL2 appears to be a more severe disorder than BSCL1 with a higher incidence of premature death and a lower prevalence of partial and/or delayed onset of lipodystrophy. Notably, subjects with BSCL2 had a significantly higher prevalence of intellectual impairment than those with BSCL1 or BSCLX (p<0.0001, OR 17.0, CI 3.6 to 79.0). The higher prevalence of intellectual impairment and the increased risk of premature death in BSCL2 compared to BSCL1 emphasise the importance of molecular diagnosis of this syndrome and have clear implications for genetic counselling.

Adolescent↗
PubMed2002

Allelic variation in exon 18 of the sulfonylurea receptor 1 (SUR1) gene, insulin secretion and insulin sensitivity in nondiabetic relatives of type 2 diabetic subjects.

BACKGROUND: We have previously observed associations of the T-allele of the exon 18 variant (ACC --> ACT; Thr759Thr) of the sulfonylurea receptor 1 (SUR1) gene with type 2 diabetes mellitus (T2DM). Here we assess beta-cell function and insulin sensitivity in carriers of different genotypes at this locus. METHODS: Pre-hepatic insulin secretion rates (ISR) derived by deconvolution of circulating C-peptide levels, and glucose clearance were assessed during graded infusions of intravenous glucose in CC-homozygous (n=6) and CT-heterozygous (n=6) nondiabetic relatives of CT-heterozygous type 2 diabetic subjects. RESULTS: Average ISR over the duration of the study, adjusted for sex, age, BMI and prevailing glucose levels, were lower in CT-heterozygous subjects as compared with CC-homozygous subjects (3.91 +/- 0.40 vs. 4.84 +/- 0.28 pmol/kg x min(-1); p=0.048). The correlation curves relating ISR to glucose levels were significantly different in the two groups (analyses of covariance p=0.029). Glucose clearance was similar in both groups. CONCLUSIONS: Insulin secretion rates, but not insulin sensitivity, assessed during graded infusion of glucose were mildly decreased in nondiabetic relatives of type 2 diabetic subjects, who carry the at risk T-allele of exon 18 variant of the SUR1 gene. These results suggest that the at-risk allele might have a small effect on pancreatic B-cell function and contribute to the development of T2DM in these families.

ATP-Binding Cassette Transporters↗
PubMed2001

[Obesity in children and adolescents, mental disorders and familial psychopathology].

OBJECTIVE: The purpose of this study was to evaluate the type and frequency of psychopathological disorders observed in obese children and adolescents. We also looked for a correlation between psychic disorders in the obese children, the degree of obesity and paternal psychopathology. PATIENTS AND METHODS: The study group included 84 obese children and adolescents aged 5 to 16 years (mean age 10.9 +/- 2.8 years). There were 55 girls and 29 boys. The z-score expressing deviation from the ideal body mass index (IMC) varied from +2 to +10.6 (mean 4 + 1.9). Psychopathological disorders observed in these obese patients were compared in children and adolescents with insulin-dependent diabetes mellitus. The standard diagnostic interview (K-SADS PL) and self-administered questionnaires (Sielberger STAIC-Trait for anxiety and CDI for depression in children or CBCL or GHQ for their parents) were also used to evaluate psychic disorders. RESULTS: More than half of the obese children (47 out of 84) had a DSM-IV diagnosis, often involving anxiety (n = 28). The rate of internalized and externalized psychopathological disorders (measured by STAIC-Trait and CBCL) was higher in the obese children than in the diabetics. The children's psychopathological disorders were more marked if their parents were perturbed, particularly when their mother had an internalized disorder. No correlation was found between the degree obesity and psychopathological disorders in the obese children and adolescents. CONCLUSION: Our findings show the frequency of mental disorders in obese children and point out the importance of parental psychopathology. This underlines the usefulness of a pedopsychiatric approach implicating the entire family for therapeutic management of these patients.

Adolescent↗
PubMed2001

Expression of the amino-terminal domain of platelet glycoprotein Ib alpha: exploitation of a calmodulin tag for determination of its functional activity.

Platelet glycoprotein (GP) Ibalpha is a component of the GPIb-IX receptor complex, which is involved in multiple physiological and pathological processes, including platelet adhesion at sites of vascular injury, thrombin binding, Bernard-Soulier syndrome, platelet-type von Willebrand disease, and immune-mediated thrombocytopenias. The amino-terminal domain of approximately 300 residues of GPIbalpha mediates both normal biological function (by providing the sites for direct ligand interaction) and aberrant function (through amino acid substitutions). To investigate the molecular interactions mediated by this region of GPIbalpha, we have developed a recombinant baculovirus to facilitate its expression as a calmodulin fusion protein from insect cells. By employing the calmodulin tag, the fusion protein could be obtained at >90% purity after a single isolation step at yields of 8 mg/L of insect cell medium (purified fusion protein). The recombinant GPIbalpha fragment was shown to be posttranslationally sulfated and glycosylated, although its glycosylation differed from that of the equivalent GPIbalpha fragment isolated from human platelets. The differential glycosylation, however, did not affect the function of the recombinant GPIbalpha fragment in either von Willebrand factor (vWf) or thrombin binding as these were both found to be identical to those of the same-length GPIbalpha fragment derived from human platelets. The calmodulin tag was also exploited in the development of assays to measure directly vWf and thrombin binding, since it did not interfere with either, demonstrating the feasibility for the use of this soluble receptor fusion protein in detailed biophysical assays to investigate the molecular mode of binding of platelet glycoprotein Ibalpha to these ligands.

Animals↗
PubMed2001

Unbalanced expression of 11p15 imprinted genes in focal forms of congenital hyperinsulinism: association with a reduction to homozygosity of a mutation in ABCC8 or KCNJ11.

Congenital hyperinsulinism (CHI), previously named persistent hyperinsulinemic hypoglycemia of infancy, is characterized by profound hypoglycemia because of excessive insulin secretion. CHI presents as two different morphological forms: a diffuse form with functional abnormality of islets throughout the pancreas and a focal form with focal islet cell adenomatous hyperplasia, which can be cured by partial pancreatectomy. Recently, we have shown that focal adenomatous hyperplasia involves the specific loss of the maternal 11p15 region and a constitutional mutation of a paternally inherited allele of the gene encoding the regulating subunit of the K(+)(ATP) channel, the sulfonylurea receptor (ABCC8 or SUR1). In the present study on a large series of 31 patients, describing both morphological features and molecular data, we report that 61% of cases (19 out of 31) carried a paternally inherited mutation not only in the ABCC8 gene as previously described but also in the second gene encoding the K(+)(ATP) channel, the inward rectifying potassium channel (KCNJ11 or KIR6.2), in 15 cases and 4 cases, respectively. Moreover our results are consistent with the presence of a duplicated paternal 11p15 allele probably because of mitotic recombination or reduplication of the paternal chromosome after somatic loss of the maternal chromosome. In agreement with the loss of the maternal chromosome, the level of expression of a maternally expressed tumor suppressor gene, H19, was greatly reduced compared to the level of expression of the paternally expressed growth promoter gene, IGF2. The expression of IGF2 was on average only moderately increased. Thus, focal forms of CHI can be considered to be a recessive somatic disease, associating an imbalance in the expression of imprinted genes in the 11p15.5 region to a somatic reduction to homozygosity of an ABCC8- or KCNJ11-recessive mutation. The former is responsible for the abnormal growth rate, as in embryonic tumors, whereas the latter leads to unregulated secretion of insulin.

ATP-Binding Cassette Transporters↗
PubMed2001

Identification of the gene altered in Berardinelli-Seip congenital lipodystrophy on chromosome 11q13.

Congenital generalized lipodystrophy, or Berardinelli-Seip syndrome (BSCL), is a rare autosomal recessive disease characterized by a near-absence of adipose tissue from birth or early infancy and severe insulin resistance. Other clinical and biological features include acanthosis nigricans, hyperandrogenism, muscular hypertrophy, hepatomegaly, altered glucose tolerance or diabetes mellitus, and hypertriglyceridemia. A locus (BSCL1) has been mapped to 9q34 with evidence of heterogeneity. Here, we report a genome screen of nine BSCL families from two geographical clusters (in Lebanon and Norway). We identified a new disease locus, designated BSCL2, within the 2.5-Mb interval flanked by markers D11S4076 and D11S480 on chromosome 11q13. Analysis of 20 additional families of various ethnic origins led to the identification of 11 families in which the disease cosegregates with the 11q13 locus; the remaining families provide confirmation of linkage to 9q34. Sequence analysis of genes located in the 11q13 interval disclosed mutations in a gene homologous to the murine guanine nucleotide-binding protein (G protein), gamma3-linked gene (Gng3lg) in all BSCL2-linked families. BSCL2 is most highly expressed in brain and testis and encodes a protein (which we have called seipin) of unknown function. Most of the variants are null mutations and probably result in a severe disruption of the protein. These findings are of general importance for understanding the molecular mechanisms underlying regulation of body fat distribution and insulin resistance.

Acanthosis Nigricans↗
PubMed2001

Degenerated pIX-IVa2 adenoviral vector sequences lowers reacquisition of the E1 genes during virus amplification in 293 cells.

A critical issue for E1-deleted adenoviral vectors manufactured from 293 cells is the emergence of replication-competent adenovirus (RCA). These contaminants arise through homologous recombination between identical sequences framing the E1 locus displayed by 293 cells, and the vector backbones. Modified recombinogenic sequences (syngen) were thus introduced within the vector backbone, and virus viability and RCA emergence were assessed. Syngen#1 is a synthetic sequence displaying silent point mutations in the pIX and IVa2 coding regions. A side by side comparison of Ad5CMV/p53 (E1-deleted adenovirus expressing the p53 tumor suppressor gene) and AVdeltaE1#1CMV/p53 (with syngen#1 in place of wild-type sequences) demonstrated a normal productivity for the modified construct. The altered sequences did not impair p53-mediated apoptosis in a model tumor cell line. Most importantly, a statistically significant decrease in terms of RCA occurrence could also be demonstrated. Degenerescence of the recombinogenic sequences could be further accentuated by modifying noncoding pIX region (syngen #2), with no effect on virus productivity and stability. We concluded that these vector modifications constitute a feasible strategy to reduce RCA emergence during amplification in 293 cells. This approach could also be applied to decrease reincorporation of the E1 genes during amplification of deltaE1deltaE4 vectors in 293/E4-trans-complementing cells.

Adenoviridae↗
PubMed2001

Aminopyrimidine-carboxyl(ate) interactions in trimethoprim maleate, an antifolate drug.

In the title cocrystal, trimethoprim maleate [2,4-diamino-5-(3,4,5-trimethoxybenzyl)pyrimidin-1-ium maleate], C(14)H(19)N(4)O(3)(+).C(4)H(3)O(4)(-), the trimethoprim molecule is protonated at N1. The carboxyl group of the maleate ion makes a specific double hydrogen bond of type N-H.O with the 2-amino group and the protonated N1 atom of the trimethoprim cation which is similar to the carboxylate-trimethoprim cation interaction observed in the complex of dihydrofolate reductase with trimethoprim. The pyrimidine moieties of trimethoprim cations are centrosymmetrically paired through a pair of N-H.N hydrogen bonds involving the 4-amino group and the pyridinium N3 atom of a symmetry-related molecule. One of the O atoms at the maleate carboxylate group bridges the 2-amino and 4-amino groups on either side of the paired trimethoprim cations. The other O atom of the carboxylate group forms an intramolecular O-H.O hydrogen bond with the carboxyl group. These characteristic hydrogen bonds result in infinite two-dimensional aggregation of rings into a supramolecular ladder, which is further crosslinked through weak C-H.O interactions with methoxy groups of neighbouring trimethoprim molecules to form a layered structure.

Crystallography, X-Ray↗
PubMed2001

Hyperinsulinism and hyperammonemia syndrome: report of twelve unrelated patients.

Hyperinsulinism and hyperammonemia syndrome has been reported as a cause of moderately severe hyperinsulinism with diffuse involvement of the pancreas. The disorder is caused by gain of function mutations in the GLUD1 gene, resulting in a decreased inhibitory effect of guanosine triphosphate on the glutamate dehydrogenase (GDH) enzyme. Twelve unrelated patients (six males, six females) with hyperinsulinism and hyperammonemia syndrome have been investigated. The phenotypes were clinically heterogeneous, with neonatal and infancy-onset hypoglycemia and variable responsiveness to medical (diazoxide) and dietary (leucine-restricted diet) treatment. Hyperammonemia (90-200 micromol/L, normal <50 micromol/L) was constant and not influenced by oral protein, by protein- and leucine-restricted diet, or by sodium benzoate or N-carbamylglutamate administration. The patients had mean basal GDH activity (18.3 +/- 0.9 nmol/min/mg protein) not different from controls (17.9 +/- 1.8 nmol/min/mg protein) in cultured lymphoblasts. The sensitivity of GDH activity to inhibition by guanosine triphosphate was reduced in all patient lymphoblast cultures (IC(50), or concentrations required for 50% inhibition of GDH activity, ranging from 140 to 580 nM, compared with control IC(50) value of 83 +/- 1.0 nmol/L). The allosteric effect of ADP was within the normal range. The activating effect of leucine on GDH activity varied among the patients, with a significant decrease of sensitivity that was correlated with the negative clinical response to a leucine-restricted diet in plasma glucose levels in four patients. Molecular studies were performed in 11 patients. Heterozygous mutations were localized in the antenna region (four patients in exon 11, two patients in exon 12) as well as in the guanosine triphosphate binding site (two patients in exon 6, two patients in exon 7) of the GLUD1 gene. No mutation has been found in one patient after sequencing the exons 5-13 of the gene.

Adolescent↗