Plasma Carotenoids and Onset of Dysglycemia in an Elderly Population: Results of the Epidemiology of Vascular Ageing Study

OBJECTIVE—The hypothesis of carotenoid having a preventive role in diabetes is suggested by their antioxidant properties. In this report, we investigated the relationship between baseline total plasma carotenoid levels and 9-year onset of dysglycemia (impaired fasting glucose or type 2 diabetes) in a healthy elderly population

Identification Aveugle de Canaux de Communication Non-linéaires basée sur la décomposition PARAFAC

Dans cet article, nous considérons l'estimation aveugle des noyaux de Volterra associés à un canal non-linéaire structuré en blocs. Pour ce type de structure, il a été montré que la connaissance des coefficients diagonaux des noyaux de Volterra est suffisante pour la caractérisation complète du modèle. Nous proposons donc un précodage de l'entrée permettant de découpler l'effet des coefficients diagonaux et non-diagonaux. Ce précodage induit une représentation tensorielle des signaux mesurés qui admet une décomposition du type PARAFAC dont l'un des facteurs est formé par les coefficients diagonaux recherchés. Nous établissons les conditions d'identifiabilité et illustrons la méthode par quelques simulations

In silico identification and expression of SLC30 family genes: An expressed sequence tag data mining strategy for the characterization of zinc transporters' tissue expression

BACKGROUND: Intracellular zinc concentration and localization are strictly regulated by two main protein components, metallothioneins and membrane transporters. In mammalian cells, two membrane transporters family are involved in intracellular zinc homeostasis: the uptake transporters called SLC39 or Zip family and the efflux transporters called SLC30 or ZnT family. ZnT proteins are members of the cation diffusion facilitator (CDF) family of metal ion transporters. RESULTS: From genomic databanks analysis, we identified the full-length sequences of two novel SLC30 genes, SLC30A8 and SLC30A10, extending the SLC30 family to ten members. We used an expressed sequence tag (EST) data mining strategy to determine the pattern of ZnT genes expression in tissues. In silico results obtained for already studied ZnT sequences were compared to experimental data, previously published. We determined an overall good correlation with expression pattern obtained by RT-PCR or immunomethods, particularly for highly tissue specific genes. CONCLUSION: The method presented herein provides a useful tool to complete gene families from sequencing programs and to produce preliminary expression data to select the proper biological samples for laboratory experimentation

The sizes of the exchangeable pools of selenium in elderly women and their relation to institutionalization

Exchangeable pools of Se after an intravenous injection of 74Se-enriched isotope as sodium selenite were measured in two groups (n 9) of elderly women (free-living aged 64-82 years and institutionalized aged 68-82 years), and a comparison group (n 9) of young women aged 31-40 years to evaluate the effect of age and institutionalization on Se reserves. Dietary Se intake was not different among the three groups. Plasma Se and glutathione peroxidase (EC 1.11.1.9) levels were significantly lower in the institutionalized elderly women (P < 0.05). In each of the three groups, two pools were determined from our model. The size of the first pool and the sum of the two pools were lower in the group of institutionalized elderly women than in the other two groups. The significant correlation between plasma Se level and total Se pool size (r 0.66, P < 0.01) indicated that this last variable could serve as a new marker of Se status. Finally, these data suggest that the Se status of elderly women is more related to lifestyle, in terms of institutionalization or not, than to age per s

In vivo expression and functional characterization of the zinc transporter ZnT8 in glucose-induced insulin secretion.

International audienceInsulin-secreting pancreatic beta cells are exceptionally rich in zinc. In these cells, zinc is required for zinc-insulin crystallization within secretory vesicles. Secreted zinc has also been proposed to be a paracrine and autocrine modulator of glucagon and insulin secretion in pancreatic alpha and beta cells, respectively. However, little is known about the molecular mechanisms underlying zinc accumulation in insulin-containing vesicles. We previously identified a pancreas-specific zinc transporter, ZnT-8, which colocalized with insulin in cultured beta cells. In this paper we studied its localization in human pancreatic islet cells, and its effect on cellular zinc content and insulin secretion. In human pancreatic islet cells, ZnT-8 was exclusively expressed in insulin-producing beta cells, and colocalized with insulin in these cells. ZnT-8 overexpression stimulated zinc accumulation and increased total intracellular zinc in insulin-secreting INS-1E cells. Furthermore, ZnT-8-overexpressing cells display enhanced glucose-stimulated insulin secretion compared with control cells, only for a high glucose challenge, i.e. >10 mM glucose. Altogether, these data strongly suggest that the zinc transporter ZnT-8 is a key protein for both zinc accumulation and regulation of insulin secretion in pancreatic beta cells

Estimating Chikungunya prevalence in La Réunion Island outbreak by serosurveys: Two methods for two critical times of the epidemic

<p>Abstract</p> <p>Background</p> <p>Chikungunya virus (CHIKV) caused a major two-wave seventeen-month-long outbreak in La Réunion Island in 2005–2006. The aim of this study was to refine clinical estimates provided by a regional surveillance-system using a two-stage serological assessment as gold standard.</p> <p>Methods</p> <p>Two serosurveys were implemented: first, a rapid survey using stored sera of pregnant women, in order to assess the attack rate at the epidemic upsurge (s1, February 2006; n = 888); second, a population-based survey among a random sample of the community, to assess the herd immunity in the post-epidemic era (s2, October 2006; n = 2442). Sera were screened for anti-CHIKV specific antibodies (IgM and IgG in s1, IgG only in s2) using enzyme-linked immunosorbent assays. Seroprevalence rates were compared to clinical estimates of attack rates.</p> <p>Results</p> <p>In s1, 18.2% of the pregnant women were tested positive for CHIKV specific antibodies (13.8% for both IgM and IgG, 4.3% for IgM, 0.1% for IgG only) which provided a congruent estimate with the 16.5% attack rate calculated from the surveillance-system. In s2, the seroprevalence in community was estimated to 38.2% (95% CI, 35.9 to 40.6%). Extrapolations of seroprevalence rates led to estimate, at 143,000 and at 300,000 (95% CI, 283,000 to 320,000), the number of people infected in s1 and in s2, respectively. In comparison, the surveillance-system estimated at 130,000 and 266,000 the number of people infected for the same periods.</p> <p>Conclusion</p> <p>A rapid serosurvey in pregnant women can be helpful to assess the attack rate when large seroprevalence studies cannot be done. On the other hand, a population-based serosurvey is useful to refine the estimate when clinical diagnosis underestimates it. Our findings give valuable insights to assess the herd immunity along the course of epidemics.</p

Interactions fonctionnelles entre la protéine transactivatrice du VIH-1, Tat, et les histones acétyltransférases

Les protéines à activité Histone AcetylTransferase (HAT) sont impliquées dans la régulation transcriptionnelle de nombreux gènes. En effet, les HAT vont, d'une part, permettre d'ouvrir localement la chromatine en acétylant les extrémités N-terminales des histones et donc rendre les promoteurs accessibles aux facteurs de transcription, et d'autre part, moduler la transcription en acétylant certains activateurs transcriptionnels cellulaires (p53,E2F) ou viraux. Le transactivateur Tat du VIH est capable d'interagir avec les HAT p300/CBP, TAFII250 et tip60. De plus, Tat est acétylé par les HAT p300/CBP et P/CAF. Au cours de mon travail de thèse, des expériences d'interaction m'ont permis de montrer que Tat interagit directement avec une autre protéine à activité HAT:la protéine GCN5. Cette interaction entre ces deux protéines va conduire à une acétylation de Tat, ce qui aura pour conséquence d'activer la transactivation au niveau du promoteur viral. De plus, nous avons montré que Tat est capable d'inhiber 'acétylation des histones par les Hat d'une façon générale aussi bien in vitro que dans la cellule. Cette action ciblée de Tat sur la capacité de ces protéines à acétyler les histones semble liée à l'inhibition de la transcription de certains gènes de défense cellulaire, notamment celui de la MnSOD, une enzyme anti-oxydante. Ainsi, le VIH "détournerait" les HATs à son profit, les utilisant d'une part pour l'acétylation de son transactivateur Tat et l'activation des gènes viraux, et réprimant leur activité d'autre part, pour modifier l'expression de gènes cellulaires.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Blind joint identification and equalization of Wiener-Hammerstein communication channels using PARATUCK-2 tensor decomposition

International audienc

Matrix and tensor decompositions for identification of block-structured nonlinear channels in digital transmission systems

International audienceIn this paper, we consider the problem of identification of nonlinear communication channels using input-output measurements. The nonlinear channel is structured as a LTI-ZMNL-LTI one, i.e. a zero-memory nonlinearity (ZMNL) sandwiched between two linear time-invariant (LTI) subchannels. Considering Volterra kernels of order higher than two as tensors, we show that such a kernel associated with a LTI-ZMNL-LTI admits a PARAFAC decomposition with matrix factors in Toeplitz form. From a third-order Volterra kernel, we show that the PARAFAC decomposition allows estimating directly the linear subchannels. In the case of a LTI-ZMNL channel, such a task is achieved by considering an eigenvalue decomposition of a given slice of such a tensor. Then, the nonlinear subsystem is estimated in the least squares sense. The proposed identification method is illustrated by means of simulation results