Reducing the burden of hypoglycaemia in people with diabetes through increased understanding: design of the Hypoglycaemia REdefining SOLutions for better liVEs (Hypo-RESOLVE) project.

BACKGROUND: Hypoglycaemia is the most frequent complication of treatment with insulin or insulin secretagogues in people with diabetes. Severe hypoglycaemia, i.e. an event requiring external help because of cognitive dysfunction, is associated with a higher risk of adverse cardiovascular outcomes and all-cause mortality, but underlying mechanism(s) are poorly understood. There is also a gap in the understanding of the clinical, psychological and health economic impact of 'non-severe' hypoglycaemia and the glucose level below which hypoglycaemia causes harm. AIM: To increase understanding of hypoglycaemia by addressing the above issues over a 4-year period. METHODS: Hypo-RESOLVE is structured across eight work packages, each with a distinct focus. We will construct a large, sustainable database including hypoglycaemia data from >100 clinical trials to examine predictors of hypoglycaemia and establish glucose threshold(s) below which hypoglycaemia constitutes a risk for adverse biomedical and psychological outcomes, and increases healthcare costs. We will also investigate the mechanism(s) underlying the antecedents and consequences of hypoglycaemia, the significance of glucose sensor-detected hypoglycaemia, the impact of hypoglycaemia in families, and the costs of hypoglycaemia for healthcare systems. RESULTS: The outcomes of Hypo-RESOLVE will inform evidence-based definitions regarding the classification of hypoglycaemia in diabetes for use in daily clinical practice, future clinical trials and as a benchmark for comparing glucose-lowering interventions and strategies across trials. Stakeholders will be engaged to achieve broadly adopted agreement. CONCLUSION: Hypo-RESOLVE will advance our understanding and refine the classification of hypoglycaemia, with the ultimate aim being to alleviate the burden and consequences of hypoglycaemia in people with diabetes.

Dairy consumption is associated with lower plasma dihydroceramides in women from the D.E.S.I.R. cohort.

AIM: In the D.E.S.I.R. cohort, higher consumption of dairy products was associated with lower incidence of hyperglycaemia, and dihydroceramide concentrations were higher in those who progressed to diabetes. Our aim here was to study the relationships between dairy consumption and concentrations of dihydroceramides and ceramides. METHODS: In the D.E.S.I.R. cohort, men and women aged 30-65 years, volunteers from West-Central France, were included in a 9-year follow-up with examinations every 3 years, including food-frequency questionnaires. Two items concerned dairy products (cheese, other dairy products except cheese). At each examination, dihydroceramides and ceramides were determined by mass spectrometry in a cohort subset; in the present study, the 105 people who did not progress to type 2 diabetes were analyzed, as the disorder per se might be a confounding factor. RESULTS: Higher consumption of dairy products (except cheese) was associated with total plasma dihydroceramides during the follow-up, but only in women (P=0.01 for gender interaction). In fact, dihydroceramide levels were lower in women with high vs low consumption (P=0.03), and were significantly increased during follow-up (P=0.01) in low consumers only. There was also a trend for lower ceramides in women with high dairy (except cheese) intakes (P=0.08). Cheese was associated with dihydroceramide and ceramide changes during follow-up (P=0.04 for both), but no clear trend was evident in either low or high consumers. CONCLUSION: These results show that, in women, there is an inverse association between fresh dairy product consumption and predictive markers (dihydroceramides) of type 2 diabetes.

Identification of a mammalian H(+)-myo-inositol symporter expressed predominantly in the brain.

Inositol and its phosphorylated derivatives play a major role in brain function, either as osmolytes, second messengers or regulators of vesicle endo- and exocytosis. Here we describe the identification and functional characterization of a novel H(+)-myo- inositol co-transporter, HMIT, expressed predominantly in the brain. HMIT cDNA encodes a 618 amino acid polypeptide with 12 predicted transmembrane domains. Functional expression of HMIT in Xenopus oocytes showed that transport activity was specific for myo-inositol and related stereoisomers with a Michaelis-Menten constant of approximately 100 microM, and that transport activity was strongly stimulated by decreasing pH. Electrophysiological measurements revealed that transport was electrogenic with a maximal transport activity reached at pH 5.0. In rat brain membrane preparations, HMIT appeared as a 75-90 kDa protein that could be converted to a 67 kDa band upon enzymatic deglycosylation. Immunofluorescence microscopy analysis showed HMIT expression in glial cells and some neurons. These data provide the first characterization of a mammalian H(+)-coupled myo- inositol transporter. Predominant central expression of HMIT suggests that it has a key role in the control of myo-inositol brain metabolism.

GLUTX1, a novel mammalian glucose transporter expressed in the central nervous system and insulin-sensitive tissues.

Based on homology with GLUT1-5, we have isolated a cDNA for a novel glucose transporter, GLUTX1. This cDNA encodes a protein of 478 amino acids that shows between 29 and 32% identity with rat GLUT1-5 and 32-36% identity with plant and bacterial hexose transporters. Unlike GLUT1-5, GLUTX1 has a short extracellular loop between transmembrane domain (TM) 1 and TM2 and a long extracellular loop between TM9 and TM10 that contains the only N-glycosylation site. When expressed in Xenopus oocytes, GLUTX1 showed strong transport activity only after suppression of a dileucine internalization motif present in the amino-terminal region. Transport activity was inhibited by cytochalasin B and partly competed by D-fructose and D-galactose. The Michaelis-Menten constant for glucose was approximately 2 mM. When translated in reticulocytes lysates, GLUTX1 migrates as a 35-kDa protein that becomes glycosylated in the presence of microsomal membranes. Western blot analysis of GLUTX1 transiently expressed in HEK293T cells revealed a diffuse band with a molecular mass of 37-50 kDa that could be converted to a approximately 35-kDa polypeptide following enzymatic deglycosylation. Immunofluorescence microscopy detection of GLUTX1 transfected into HEK293T cells showed an intracellular staining. Mutation of the dileucine internalization motif induced expression of GLUTX1 at the cell surface. GLUTX1 mRNA was detected in testis, hypothalamus, cerebellum, brainstem, hippocampus, and adrenal gland. We hypothesize that, in a similar fashion to GLUT4, in vivo cell surface expression of GLUTX1 may be inducible by a hormonal or other stimulus.

Analysis of T cell receptor V alpha polymorphisms in rheumatoid arthritis.

OBJECTIVE: To test for association of T cell receptor (TCR) V alpha polymorphisms and rheumatoid arthritis (RA) in British and Swiss white populations. METHODS: TCRAV polymorphisms were analysed in RA patients and controls by single strand conformational polymorphism (SSCP) analysis. Associations were sought between defined genotypes and RA, and the effect of HLA-DR4 status analysed. Putative associations were then retested further in new groups of patients and controls. Overall, 360 RA patients and 197 controls were studied. RESULTS: No association between TCRAV5S1, V6S1, V8S1, V17S1 or V21S1 polymorphisms and RA were observed in the initial population screened. Stratification for DR4 status showed an increase of V5S1*01/*01 in DR4 positive versus DR4 negative patients (chi 2 = 7.19, p = 0.028 (2df), p = 0.14 after correction for multiple comparisons). This putative association was tested in three further patient groups, none of which showed significant increase of V5S1*01/*01 in DR4 positive patients, although an overall trend towards an increase in V5S1*01/*01 was observed. CONCLUSION: No evidence was found for a strong association of TCRAV genes and RA in a white population. However, these results suggest a weak association of V5S1*01/*01 with DR4 positive RA, although this requires confirmation using larger groups of patients and controls.

T-cell receptor variable alpha (TCRAV) polymorphisms in European, Chinese, South American, AfroCaribbean, and Gambian populations.

Interactions involving the T-cell receptor (TCR) and major histocompatibility complex (MHC) are fundamental to the generation of a specific immune response. The study of interpopulation differences in TCR genes may identify those genes which are subject to selection, and also provides useful information for future genetic studies in these populations. In this study we present analysis of five TCRAV polymorphisms, for V5S1, V6S1, V8S1, V17S1, and V21S1 loci in five human populations by single-strand conformational polymorphism (SSCP) analysis. Caucasian, Chinese, Gambian, AfroCaribbean, and South American Indians (Mapuches) showed marked interpopulation variation for both the silent (V5S1, V17S1, and V21S1) and coding (V6S1 and V8S1) polymorphisms. In general the alleles were conserved in the different populations, but new, additional variants were found for V5S1 and V17S1 in Gambians and Caucasians. V6S1 overall showed the highest nucleotide diversity, and V6S1 genotype distributions were skewed away from expected values in Chinese and Mapuches. Analysis of allelic associations showed a general lack of linkage disequilibrium between the loci, which was reflected by the absence of strong population-specific haplotypes.

Genomic organization of the human T-cell receptor variable alpha (TCRAV) gene cluster.

A long-range physical map of the human T-cell receptor variable alpha (TCRAV) locus was produced using 23 V alpha subgroup-specific probes. Linkage disequilibrium across the locus was also studied using polymorphic TCRAV markers. Pulsed-field gel electrophoresis was used to map V alpha gene segments onto one SfiI fragment of 500 kb and two of 200 kb using DNA from peripheral blood neutrophils. PCR and conventional Southern techniques on Jurkat, CEM, and H9 T-cell lines were used to establish the 5' to 3' order of the gene segments and the relative positions of V alpha gene segments on the SfiI fragments. The linkage disequilibrium study used single-stranded conformation polymorphism analysis to genotype 100 normal caucasoid subjects for TCRAV5S1, V6S1, V8S1, V17S1, and V21S1 polymorphisms. Strong linkage disequilibrium was detected between V5S1 and V8S1, in concordance with the physical map. This new information will be useful for future studies of genetic variation at the TCRAV locus, its role in the shaping of the TCR repertoire, and its possible contribution to autoimmune diseases.

Lack of association of T cell receptor V beta 8 polymorphism with rheumatoid arthritis in United Kingdom and Italian white patients.

OBJECTIVES: To study if the reported association of a BamH I 2kb RFLP of the T cell receptor V beta 8 gene with DR4+ rheumatoid arthritis patients is found in non-American white populations. METHODS: The frequency of this RFLP in two different populations was analysed. Eighty one northern Italians were studied for HLA-DR genotypes and V beta 8 polymorphism, and 29 DR4+ British white patients were studied for V beta 8 polymorphism. RESULTS: No association between the V beta 8 RFLP and DR4 was found with rheumatoid arthritis in both groups. CONCLUSION: The reported V beta 8-DR4 association is not generally applicable. The lack of association in our populations may be due to genetic differences, or to differences in factors which shaped the T cell repertoire.