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Biomedical subjects

J Timsit

Publications and source records attributed to J Timsit.

At least 37 records · Page 2Linked to original sources
PubMed2000

Association of a variant in exon 31 of the sulfonylurea receptor 1 (SUR1) gene with type 2 diabetes mellitus in French Caucasians.

The sulfonylurea receptor (SUR1) of the pancreatic beta-cell ATP-sensitive potassium channel plays a key role in glucose-induced insulin secretion. The A-allele of a single nucleotide polymorphism (SNP) in exon 31 of the SUR1 gene (AGG-->AGA; Arg1273Arg) has previously been shown to be associated with hyperinsulinemia in nondiabetic Mexican-American subjects. Here, we have investigated the association of this SNP with type 2 diabetes mellitus (T2DM) in French Caucasian subjects. We have observed an increased frequency of the A allele (37.1% vs 27.6%, P=0.0048; odds ratio 1.54), of the AA genotype (15.7% vs 9.8%; P=0.025), and of the combined AA/AG genotypes (58.5% vs 45.5%, P=0.0098; odds ratio 1.69) in patients compared with controls. This association is stronger in the subgroup of patients with age of diagnosis of diabetes equal to or less than 45 years: A allele 43.2% (P=0.0003 compared with controls; odds ratio 1.99), AA genotype 21.4% (P=0.0032), and combined AA/AG genotypes 65.1% (P=0.0022; odds ratio 2.23). Unexpectedly, the G allele is strongly associated with arterial hypertension in obese diabetic subjects (GG vs AA odds ratio 19.97). In conclusion, we have observed an association of an SNP in exon 31 of the SUR1 gene with T2DM. These data reinforce the hypothesis that insulin secretion defects in T2DM might be at least partially related to allelic variations in the SUR1 gene.

ATP-Binding Cassette Transporters↗
PubMed2000

Sequential occurrence of thyroid autoantibodies and Graves' disease after immune restoration in severely immunocompromised human immunodeficiency virus-1-infected patients.

We analyzed the kinetics of CD4 cells, human immunodeficiency virus (HIV) viral load, and autoantibodies in acquired immune deficiency syndrome patients with Graves' disease (GD) after immune restoration on highly active antiretroviral therapy (HAART; retrospective study). Five patients (median age, 41 yr) were diagnosed with GD after 20 (range, 14-22) months on HAART on the basis of clinical and biological hyperthyroidism, diffuse hyperfixation of thyroid scan, and the presence of anti-TSH receptor (anti-TSHR) antibodies (Ab). GD was diagnosed several months after the plasma HIV ribonucleic acid load became undetectable, when the CD4+ cell count had risen from 14 (range, 0-62) to 340 (range, 163-460) x 10(6) cells/L. Antithyroid peroxidase (anti-TPO) and anti-TSHRAb appeared 14 (range, 9-18) and 14 (range, 11-20) months after starting HAART and 12 (range, 6-15) and 11 (range, 9-17) months after the increase in CD4+ cells. In 3 patients, TPOAb preceded TSHRAb by 3-10 months. No other autoantibodies were detected. Thyroid antibodies were absent in a group of 55 HIV-1-positive patients with comparable response to HAART and no symptoms of hyperthyroidism (cross-sectional study). Thyroid-specific autoimmunity can occur upon immune restoration with HAART. Our observations suggest a relationship between thymus-dependent immune reconstitution after immunosuppression and autoimmunity and may provide insight into the pathophysiology of GD.

Adult↗
PubMed2000

Mutations in the insulin promoter factor-1 gene in late-onset type 2 diabetes mellitus.

OBJECTIVE: Insulin promoter factor-1 (IPF-1) is a transcription factor expressed in pancreatic beta cells. Following the identification of missense variants in the coding regions of the IPF-1 gene, in subjects selected for a strong family history of type 2 diabetes, the aim of our study was to evaluate the prevalence of these variants in the common form of type 2 diabetes. METHODS: Three variants (C18R, Q59L and D76N) were screened by PCR-RFLP in a group of 296 unrelated French late-onset type 2 diabetic subjects consecutively recruited in a diabetes department of a university hospital, regardless of family history of diabetes. RESULTS: The C18R and Q59L variants were each found in 0.37% of the diabetic patients, and in none of 147 controls. We did not detect the D76N variant, which was the most frequent variant in subjects with a strong family history of diabetes, in patients or controls. CONCLUSIONS: We have observed a combined prevalence of missense variants in the coding region of the IPF-1 gene of around 1%, in unselected patients with the common form of late-onset type 2 diabetes. The prevalence of these variants in subjects with a strong family history of type 2 diabetes had been found to be as high as approximately 6%. These differences in prevalence might be related to differences in the clinical profile of patients, such as age of onset of diabetes and associated obesity, as well as a family history of diabetes.

Age of Onset↗
PubMed2000

[Etiopathogeny of fetal macrosomia].

Fetal macrosomia is an heterogeneous condition in terms of definition and etiologic factors. Recent findings suggest that macrosomia should not be classified on the basis of birth weight and gestational age alone. The ponderal index delineates a symmetric and an asymmetric subtype of macrosomia. The relationship between maternal diabetes and fetal macrosomia has been extensively investigated. However, eighty percent of macrosomic infants are born to mothers who are not hyperglycemic, and various factors have been associated. Maternal factors explain approximately 50% of the variance in birth weight, whereas paternal factors have no significant effect. The predisposition to excessive fetal growth may be shared within the intra uterine environment and the fetal genome. The respective roles of lipids, amino acids, hormones such as leptin, and growth factors need to be evaluated. Perinatal morbidity and long term consequences such as obesity and glucose intolerance might be associated with some of the factors leading to fetal overgrowth.

Embryonic and Fetal Development↗
PubMed2000

Clinical characteristics of type 2 diabetes in patients with mutations of HFE.

Genetic hemochromatosis (GH) is associated with two mutations of the HFE gene (Cys282Tyr and His63Asp). Heterozygosity for GH is associated with a mild increase in iron metabolism parameters, and increased iron stores are associated with abnormal glucose tolerance and decreased insulin sensitivity in the general population. We have previously shown that the frequency of the two HFE mutations is not increased in patients with type 2 diabetes. However, to assess whether the presence of HFE mutations modulates the clinical presentation of type 2 diabetes, we studied the clinical characteristics and iron metabolism indexes according to the presence of the two mutations in 266 patients with type 2 diabetes. The Cys282Tyr mutation and the His63Asp mutation were present in 9. 8% and 26% of the patients, respectively. Serum iron, transferrin saturation and ferritin concentrations were significantly increased in patients expressing either HFE mutations, compared to those without any mutation. There was no difference in the clinical characteristics in the two groups except that obesity was significantly less frequent in the patients with at least one mutation than in those without any mutation (27.6% vs 42.8%, p=0.02). This finding suggests that, in the absence of obesity, HFE mutations, through the insulin resistance associated with the increase in iron stores, may contribute to the onset of type 2 diabetes.

Amino Acid Substitution↗
PubMed2000

[Is diabetes mellitus a sufficient condition to suspect hemochromatosis?].

Genetic Hemochromatosis (GH) is a highly prevalent autosomal recessive disorder, which outcome has been dramatically improved by early phlebotomy. Attempts to screen for the disease, using biological and genetic approaches, are currently under evaluation. Diabetes mellitus often complicates GH. However, as it occurs late in the course of the disease, in most cases when cirrhosis is already present, its usefulness for the screening of GH seems reduced. Diabetes mellitus, when isolated, appears also as a poor predictor of hemochromatosis. Indeed, the risk of being carrier of the disease is not increased in diabetic patients compared with non diabetic sujects. This risk is however highly enhanced by the co-existence of cirrhosis. Thus, in the face of a newly diagnosed diabetes mellitus, the search for hemochromatosis must be performed only when it associates with cirrhosis or with other evocative clinical conditions.

Diabetes Complications↗
PubMed2000

[Should the occurrence of a first coronary event change the management of diabetes?].

The coronary morbi-mortality is particularly high in type 2 diabetes, which represents the vast majority of all diabetes. Hyperglycemia is an independent vascular risk factor in the short and long-term. The relationship between the degree of hyperglycemia and vascular risk is linear with no threshold effect. The occurrence of a first coronary event is an occasion, though late, to review the management of all risk factors in diabetic patients. In these patients, intensive insulin therapy administered in the acute phase of infarction reduces cardiovascular mortality by 30% at 1 and 3 years. There are no specific studies of secondary prevention by optimal therapy of diabetes, but, in the UKPDS, the treatment of hyperglycemia with sulfonylurea or insulin only marginally reduced the number of cardiovascular events. On the other hand, treatment of obese patients with metformin significantly reduced the incidence of myocardial infarction and of mortality diabetes related. These results, though observed with the same level of glycemic control as in the other treatment groups, suggest a cardio-protective effect of metformin itself. These beneficial effects should be weighed up against the potential risk of lactic acidosis which still limits the widespread use of metformin in with coronary heart disease patients. Follow-up studies show that diabetic with coronary heart disease patients do not receive all effective therapeutic inventions in secondary prevention and that the treatment of hyperglycemia is often neglected. Close collaboration between cardiologists and diabetologists is necessary to improve the management of type 2 diabetes.

Acidosis, Lactic↗
PubMed1999

[Type 1 diabetes mellitus].

POSITIVE DIAGNOSIS: Among the various diseases leading to chronic hyperglycemia, type 1 diabetes mellitus is distinctive by the presence of specific autoantibodies. The common from of type 1 diabetes mellitus is insulin-dependant diabetes, but type 1 diabetes may also present as non-insulin-dependent. In order to predict insulin-dependence and screen for associated autoimmune diseases, search for autoantibodies is required in all patients with diabetes, whatever the clinical presentation. COMPLEX PATHOPHYSIOLOGY: Diabetes mellitus is a multifactorial disease implicating of environmental and genetic factors leading to breakdown immune tolerance. LONG PRECLINICAL PHASE: Chronic hyperglycemia is preceded by a long preclinical phase during which the only observable anomalies result from activation of the immune system. With the development of simplified techniques for detecting autoantibodies, it would be reasonable to foresee large-scale screening. ONGOING SECONDARY PREVENTION TRIALS: The goal is to prevent the development of chronic hyperglycemia by intervening early, during the infraclinical phase, in patients with signs of immune activation. AT THE TIME OF DIAGNOSIS: When diabetes is discovered, intensive insulin therapy helps preserve residual insulin secretion and guarantees better long-term metabolic control.

Chronic Disease↗
PubMed1999

Macrosomia revisited: ponderal index and leptin delineate subtypes of fetal overgrowth.

OBJECTIVES: We sought to reanalyze the concept of fetal macrosomia with regard to the ponderal index and to investigate the role of insulin, insulinlike growth factor I, leptin, and maternal factors on birth size in a population of infants with nondiabetic mothers. STUDY DESIGN: Venous cord blood levels of insulin, insulinlike growth factor I, insulinlike growth factor binding protein 3, and leptin were measured in 28 large-for-gestational-age and 21 appropriate-for-gestational-age newborns. RESULTS: Large-for-gestational-age newborns can be divided into symmetric and asymmetric subtypes according to the ponderal index. Mean leptin concentrations in cord blood were significantly higher in asymmetric than in symmetric large-for-gestational-age newborns (P =.01). A positive correlation was observed between leptin and the ponderal index (r = 0.53, P =.001) and between leptin and insulin concentrations in cord blood (r = 0.53, P =.008). CONCLUSION: Our results strongly suggest that macrosomia should not be classified on the basis of birth weight and gestational age alone. We also show that asymmetric macrosomic infants with nondiabetic mothers have abnormal leptin and insulin concentrations.

Embryonic and Fetal Development↗
PubMed1999

Insulin secretion and insulin sensitivity in diabetic and non-diabetic subjects with hepatic nuclear factor-1alpha (maturity-onset diabetes of the young-3) mutations.

OBJECTIVE: To evaluate insulin secretion and sensitivity in affected (diabetes mellitus or impaired glucose tolerance; n=7) and in unaffected (normal glucose tolerance; n=3) carriers of hepatocyte nuclear factor-1alpha (maturity-onset diabetes of the young-3 (MODY3)) gene mutations. METHODS: Insulin secretion was assessed by an i.v. glucose tolerance test (IVGTT), hyperglycemic clamp and arginine test, and insulin sensitivity by an euglycemic hyperinsulinemic clamp. Results were compared with those of diabetic MODY2 (glucokinase-deficient) and control subjects. RESULTS: The amount of insulin secreted during an IVGTT was decreased in affected MODY3 subjects (46+/-24 (s.d.) pmol/kg body weight (BW)) as compared with values in MODY2 (120+/-49pmol/kg BW) and control (173+/-37pmol/kg BW; P=0.0004) subjects. The amount of insulin secreted during a 10mmol/l glucose clamp was decreased in affected MODY3 subjects (171+/-78pmol/kg BW) and MODY2 subjects (302+/-104pmol/kg BW) as compared with control subjects (770+/-199pmol/kg BW; P=0.0001). Insulin secretion in response to arginine was decreased in affected MODY3 subjects. Milder and heterogeneous defects were observed in the unaffected MODY3 subjects; the amount of insulin secreted during the hyperglycemic clamp was 40-79% of that of controls. The response to arginine was abnormally delayed. Insulin sensitivity was decreased in diabetic but not in non-diabetic MODY3 subjects. CONCLUSIONS: Beta-cell dysfunction in response to glucose and arginine is observed in affected and unaffected MODY3 subjects. The MODY3 and MODY2 subtypes present different insulin secretion profiles. Secondary insulin resistance might contribute to the chronic hyperglycemia of MODY3 patients and modulate their glucose tolerance.

Adolescent↗
PubMed1999

A large subset of neutrophils expressing membrane proteinase 3 is a risk factor for vasculitis and rheumatoid arthritis.

It has been shown previously that proteinase 3 (PR3), a neutrophil intracellular protease that is the main antigen of antineutrophil cytoplasm (ANCA) autoantibodies, is present on the plasma membrane of a subset of freshly isolated neutrophils. This study shows that the size of this subset of membrane PR3-positive (mPR3+) neutrophils is a stable feature of a given individual, most likely genetically controlled. It ranges from 0 to 100% of neutrophils and allows us to define a new polymorphism in the healthy population, with three discrete phenotypes corresponding respectively to less than 20% mPR3 + neutrophils (mPR3low) or to a mean percentage of 47% (mPR3intermediate) and 71.5% (mPR3high) mPR3+ neutrophils. The frequency of the mPR3high phenotype was significantly increased in patients with ANCA-associated vasculitis (85% versus 55% in healthy subjects). The percentage of mPR3+ neutrophils was not affected by disease activity, relapses, or therapy, and did not reflect in vivo cell activation. In addition, mPR3+ phenotypes were normally distributed in cystic fibrosis patients, indicating that infection and/or inflammation per se do not lead to a high percentage of mPR3+ neutrophils. The frequency of the mPR3high phenotype was not related to anti-PR3 autoimmunization, since it was increased in vasculitic patients regardless of the ANCA specificity (anti-PR3, anti-myeloperoxidase, or unknown). Interestingly, the frequency of the mPR3high phenotype was also increased in patients with rheumatoid arthritis. It was normal in type I-diabetes, a T cell-dependent autoimmune disease. It is proposed here that a high proportion of membrane PR3-positive neutrophils could favor the occurrence or the progression of chronic inflammatory diseases.

Adult↗
PubMed1999

[Diabetes and pregnancy].

The presence of insulin-dependent or non insulin-dependent diabetes mellitus in pregnant women has been associated with an adverse effect on the maternal an fetal outcomes of pregnancy. The incidence of obstetrical and diabetic complications is increased, and a continuum has been observed between maternal blood glucose levels and perinatal outcome. The incidence of congenital malformations, macrosomia and prematurity is increased in offspring of diabetic mothers. Programming and intensive collaborative follow-up improve the outcome of such pregnancies. Gestational diabetes mellitus is an heterogenous condition defined as carbohydrate intolerance of variable severity with onset or first recognition during pregnancy. Short term complications are mainly represented by fetal macrosomia and high cesarean section rate. Women with a history of gestational diabetes mellitus are at increased risk of future diabetes, predominantly type 2. Obesity and type 2 diabetes are increased among their children.

Breast Feeding↗
PubMed1999

Insulin autoimmune syndrome: a rare cause of hypoglycaemia not to be overlooked.

We report the case of a Caucasian patient with insulin autoimmune syndrome (IAS), defined as the association of hypoglycaemic attacks with insulin autoantibodies in individuals not previously treated with exogenous insulin. This rare syndrome (more than 200 published cases) has been reported mainly in Japan. Most affected patients present with other autoimmune disorders, most often Graves' disease. In most cases, insulin autoantibodies appear a few weeks after the beginning of treatment with a drug containing a sulphyldryl group. A significant increase in insulin and C-peptide plasma concentrations and the presence of other antiorgan antibodies are observed. The susceptibility haplotype is present in the Japanese population, which may account for the high frequency of IAS. Spontaneous remission is observed in 80% of cases, with cessation of hypoglycaemic attacks and disappearance of insulin autoantibodies some months after withdrawal of the drug. This rare cause of hypoglycaemia in Caucasian subjects should be considered in aetiologic investigation of spontaneous hypoglycaemia.

Antithyroid Agents↗
PubMed1998

Mutation screening in 18 Caucasian families suggest the existence of other MODY genes.

Maturity-onset diabetes of the young (MODY) is a heterogeneous subtype of non-insulin-dependent diabetes mellitus characterised by early onset, autosomal dominant inheritance and a primary defect in insulin secretion. To date five MODY genes have been identified: hepatocyte nuclear factor-4 alpha (HNF-4alpha/MODY1/TCF14) on chromosome 20q, glucokinase (GCK/MODY2) on chromosome 7p, hepatocyte nuclear factor-1 alpha (HNF-1alpha/MODY3/TCF1) on chromosome 12q, insulin promoter factor-1 (IPF1/MODY4) on chromosome 13q and hepatocyte nuclear factor-1 beta (HNF-1beta/MODY5/TCF2) on chromosome 17cen-q. We have screened the HNF-4alpha, HNF-1alpha and HNF-1beta genes in members of 18 MODY kindreds who tested negative for glucokinase mutations. Five missense (G31D, R159W, A161T, R200W, R271W), one substitution at the splice donor site of intron 5 (IVS5nt + 2T-->A) and one deletion mutation (P379fsdelT) were found in the HNF-1alpha gene, but no MODY-associated mutations were found in the HNF-4alpha and HNF-1beta genes. Of 67 French MODY families that we have now studied, 42 (63%) have mutations in the glucokinase gene, 14 (21%) have mutations in the HNF-1alpha gene, and 11 (16%) have no mutations in the HNF-4alpha, IPF1 and HNF-1beta genes. Eleven families do not have mutations in the five known MODY genes suggesting that there is at least one additional locus that can cause MODY.

Adult↗
PubMed1998

Major histocompatibility class II genes polymorphism in insulin dependent diabetes mellitus with or without associated thyroid autoimmunity.

Insulin dependent diabetes mellitus (IDDM) is sometimes associated with extrapancreatic organ-specific autoimmune diseases, but whether this phenotype results from a peculiar genetic profile is still unclear. The allelic distribution of the major histocompatibility complex (MHC) class II genes (HLA-DRB1, DQA1, DQB1 and TAP) was analysed in 143 patients with IDDM alone by comparison with 82 IDDM patients with autoimmune thyroid disease (IDDM/AITD). The frequency of the DQB1*0301 IDDM-protective phenotype seemed to be lower in IDDM than in IDDM/AITD patients (16.8% vs 30.5% respectively, p = 0.02). By contrast, the frequency of the DRB1*04-DQB1*0302 IDDM-predisposing phenotype was higher in IDDM than in IDDM/AITD patients (91.3% vs 76.1% of DR4-positive patients respectively, p = 0.007), but these differences were not significant after correcting the p values, except in the case of the DRB1*0405-DQB1*0302 combination (21.3% vs 2.4% of DR4-positive patients, Pc = 0.05). Furthermore, all differences disappeared when patients were matched for age at IDDM-onset. Our data do not long give support for a particular role of MHC class II genes in favouring the occurrence of thyroid autoimmunity in IDDM patients, but rather suggest that some class II alleles or residues might determine the rapidity of progression to IDDM in genetically susceptible individuals. The involvement of non-MHC genes and/or environmental factors remains to be determined.

ATP Binding Cassette Transporter, Subfamily B, Mem↗