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S C Bain

Publications and source records attributed to S C Bain.

At least 55 records · Page 3Linked to original sources
PubMed1996

The CTLA-4 gene region of chromosome 2q33 is linked to, and associated with, type 1 diabetes. Belgian Diabetes Registry.

Susceptibility to autoimmune insulin-dependent (type 1) diabetes mellitus is determined by a combination of environmental and genetic factors, which include variation in MHC genes on chromosome 6p21 (IDDM1) and the insulin gene on chromosome 11p15 (IDDM2). However, linkage to IDDM1 and IDDM2 cannot explain the clustering of type 1 diabetes in families, and a role for other genes is inferred. In the present report we describe linkage and association of type 1 diabetes to the CTLA-4 gene (cytotoxic T lymphocyte associated-4) on chromosome 2q33 (designated IDDM12). CTLA-4 is a strong candidate gene for T cell-mediated autoimmune disease because it encodes a T cell receptor that mediates T cell apoptosis and is a vital negative regulator of T cell activation. In addition, we provide supporting evidence that CTLA-4 is associated with susceptibility to Graves' disease, another organ-specific autoimmune disease.

Abatacept↗
PubMed1996

Altered insulin secretory responses to glucose in diabetic and nondiabetic subjects with mutations in the diabetes susceptibility gene MODY3 on chromosome 12.

One form of maturity-onset diabetes of the young (MODY) results from mutations in a gene, designated MODY3, located on chromosome 12 in band q24. The present study was undertaken to define the interactions between glucose and insulin secretion rate (ISR) in subjects with mutations in MODY3. Of the 13 MODY3 subjects, six subjects with normal fasting glucose and glycosylated hemoglobin and seven overtly diabetic subjects were studied as were six nondiabetic control subjects. Each subject received graded intravenous glucose infusions on two occasions separated by a 42-h continuous intravenous glucose infusion designed to prime the beta-cell to secrete more insulin in response to glucose. ISRs were derived by deconvolution of peripheral C-peptide levels. Basal glucose levels were higher and insulin levels were lower in MODY3 subjects with diabetes compared with nondiabetic subjects or with normal healthy control subjects. In response to the graded glucose infusion, ISRs were significantly lower in the diabetic subjects over a broad range of glucose concentrations. ISRs in the nondiabetic MODY3 subjects were not significantly different from those of the control subjects at plasma glucose levels <8 mmol/l. As glucose rose above this level, however, the increase in insulin secretion in these subjects was significantly reduced. Administration of glucose by intravenous infusion for 42 h resulted in a significant increase in the amount of insulin secreted over the 5-9 mmol/l glucose concentration range in the control subjects and nondiabetic MODY3 subjects (by 38 and 35%, respectively), but no significant change was observed in the diabetic MODY3 subjects. In conclusion, in nondiabetic MODY3 subjects insulin secretion demonstrates a diminished ability to respond when blood glucose exceeds 8 mmol/l. The priming effect of glucose on insulin secretion is preserved. Thus, beta-cell dysfunction is present before the onset of overt hyperglycemia in this form of MODY. The defect in insulin secretion in the nondiabetic MODY3 subjects differs from that reported previously in nondiabetic MODY1 or mildly diabetic MODY2 subjects.

Adolescent↗
PubMed1995

Analysis of the CD3 gene region and type 1 diabetes: application of fluorescence-based technology to linkage disequilibrium mapping.

The CD3 gene region on chromosome 11q23 has been implicated in susceptibility to type 1 (insulin-dependent) diabetes mellitus. Using semi-automated fluorescence-based technology, we have undertaken association and linkage analysis of a dinucleotide microsatellite in the CD3 delta (CD3D) gene. We have also performed a large case-control analysis of a restriction fragment length polymorphism (RFLP) in the CD3 epsilon (CD3E) gene, 26 kb from CD3D. We found no evidence for the previously reported association between the 8 kb allele of the RFLP and disease in a UK dataset of 403 diabetic patients and 446 nondiabetic controls. Furthermore, the use of the transmission/disequilibrium test (TDT) showed no evidence of linkage or association to type 1 diabetes at either marker locus. We conclude that the CD3 gene region does not contribute significantly to IDDM susceptibility. We have successfully applied semi-automated, fluorescence-based technology to undertake association analysis on the CD3D microsatellite. Moreover, by analysing 94 other dinucleotide repeat markers, we conclude that fluorescence-based methodology can generally be applied to large-scale, semi-automated association studies with most microsatellite markers.

Adolescent↗
PubMed1995

Nephropathy in type 1 diabetes: the role of genetic factors.

Diabetic nephropathy affects up to 30% of all patients with Type 1 (insulin-dependent) diabetes and is associated with a high morbidity and mortality. A number of studies have suggested that, unlike retinopathy or neuropathy, the influence of hereditary factors on the development of nephropathy is strong. Much interest has focused on possible genetic markers indicating an increased risk for developing diabetic nephropathy. It is envisaged that patients with Type 1 diabetes may be screened at diagnosis for increased susceptibility to nephropathy and subsequently have intensified follow up and possibly even prophylactic therapy in order to prevent progression to nephropathy. Two groups of candidate genes have so far been of particular interest: those implicated in the aetiology of hypertension, and those involved in the metabolism of glomerular basement membrane proteins. This article aims to review the evidence suggesting a role for hereditary factors, possible genetic models, and the genetic loci thought to be involved.

Aldehyde Reductase↗
PubMed1994

Parental origin of diabetes-associated HLA types in sibling pairs with type I diabetes.

Genetic susceptibility to type I diabetes is partly determined by genes located in the human leukocyte antigen (HLA) region on chromosome 6. It has been claimed that the transmission of HLA-encoded susceptibility is influenced by parental sex. Fathers are reported to transmit HLA-DR4 haplotypes more frequently to their diabetic offspring than mothers. More recently, it has been suggested that the presence of HLA-DR4 in a mother may influence susceptibility in her offspring, even when it is not inherited. We have analyzed 172 multiplex diabetic pedigrees from the U.K. and find no evidence to support an important effect of parental sex on the inheritance of HLA-encoded susceptibility. Examination of a further 110 pedigrees from the U.S. supports this finding. These results have important implications for strategies involving genetic screening for type I diabetes.

Adolescent↗
PubMed1992

Insulin gene region-encoded susceptibility to type 1 diabetes is not restricted to HLA-DR4-positive individuals.

Type 1 or insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease of the insulin-producing pancreatic beta-cells which is determined by both genetic and environmental factors. The major histocompatibility complex and the insulin gene region (INS) on human chromosomes 6p and 11p, respectively, contain susceptibility genes. Using a mostly French data set, evidence for linkage of INS to IDDM was recently obtained but only in male meioses (suggesting involvement of maternal imprinting) and only in HLA-DR4-positive diabetics. In contrast, we find evidence for linkage in both male and female meioses and that the effect of the susceptibility gene(s) in the INS region is not dependent on the presence of HLA-DR4.

Base Sequence↗
PubMed1992

A practical approach to identification of susceptibility genes for IDDM.

Of all the common diseases that have a genetic component, IDDM is probably the most tractable to the experimentalist. Large numbers of nuclear multiplex families are available, which can be stored as permanent cell lines; diagnosis is relatively unambiguous; and a mouse strain, the NOD, spontaneously develops autoimmune IDDM similar to the human disorder. In addition, the resolution and accessibility of the human genome map has been revolutionized by the discovery and widespread application of the PCR, particularly the amplification of short, tandemly repeated segments of DNA called microsatellites, which display high levels of allelic polymorphism. With these reagents, the stage is set for dissection of the genetic factors that control the pathophysiology of IDDM.

Animals↗
PubMed1991

Comparison of the free radical scavenging activity of captopril versus enalapril: a three month in vivo study in hypertensive diabetic patients.

Lipid peroxides and fluorescent serum proteins, possible markers of free radical activity, are increased in diabetic patients, particularly those with angiopathy. Captopril, an angiotensin converting enzyme (ACE) inhibitor, scavenges free radicals in vitro independently of ACE inhibition. This is probably due to the presence of a sulphydryl group which is not present in other ACE inhibitor drugs. We have compared the effects of captopril and enalapril on free radical activity in thirty-two diabetic subjects with hypertension (BP greater than 160/95 mmHg). After a three week run-in period on no antihypertensive therapy, patients were randomly allocated to receive captopril or enalapril, the dose titrated according to BP response. After three months, BP was well controlled in both groups and glycaemic control unchanged. Both drugs were associated with a reduction of fluorescent IgG (captopril:Baseline [BL] 0.564 vs. 12 weeks [w] 0.428, P less than 0.05, enalapril:BL 0.603 vs. 12w 0.422 P less than 0.05) and thiobarbituric acid reactive material (captopril:BL 2.35 nmol MDA vs. 12w 1.46 nmol, P less than 0.05, enalapril:BL 2.44 nmol vs. 12w 1.72 nmol, P less than 0.01). In contrast to in vitro studies, there was no significant difference between the drugs when used in therapeutic doses, questioning a hypothesised advantage of captopril over enalapril.

Adult↗