Influence of Genetic Risk Factors on Coronary Heart Disease Occurrence in Afro-Caribbeans.

BACKGROUND: Despite excessive rates of cardiovascular risk factors such as hypertension, diabetes, and obesity, Afro-Caribbeans have lower mortality rates from coronary heart disease (CHD) than do whites. This study evaluated the association of genetic risk markers previously identified in whites and CHD in Afro-Caribbeans. METHODS: We studied 537 Afro-Caribbean individuals (178 CHD cases and 359 controls) who were genotyped for 19 CHD-related single-nucleotide polymorphisms (SNPs). A genetic risk score (GRS) incorporating the 19 SNPs was calculated. These participants were compared with 1360 white individuals from the Second Northwick Park Heart Study. RESULTS: In Afro-Caribbeans, patients with CHD had higher rates of hypertension (78.7% vs 30.1%), hypercholesterolemia (52.8% vs 15.0%), and diabetes (53.9% vs 14.8%) and were more often men (64.0% vs 43.7%) and smokers (27.5% vs 13.4%) compared with non-CHD controls (all P < 0.001). The GRS was higher in Afro-Caribbeans with CHD than in those without CHD (13.90 vs 13.17; P < 0.001) and was significantly associated with CHD after adjustment for cardiovascular risk factors, with an odds ratio of 1.40 (95% confidence interval, 1.09-1.80) per standard deviation change. There were significant differences in allelic distributions between the 2 ethnic groups for 14 of the 19 SNPs. The GRS was substantially lower in Afro-Caribbean controls compared with white controls (13.17 vs 16.59; P < 0.001). CONCLUSIONS: This study demonstrates that a multilocus GRS composed of 19 SNPs associated with CHD in whites is a strong predictor of the disease in Afro-Caribbeans. The differences in CHD occurrence between Afro-Caribbeans and whites might be a result of significant discrepancies in common gene variant distribution.

Interfacial energy-dispersive spectroscopy profile X-ray resolution measurements in variable pressure SEM.

A procedure has been developed to follow degradation of energy-dispersive spectroscopy (EDS) X-ray lateral resolution in a variable pressure scanning electron microscope. This procedure is based on evaluation of the EDS profile shape change for different experimental conditions. Some parameters affecting the X-ray resolution in high-vacuum mode have been taken into account. Good agreement between the simulated and experimental EDS profiles shows the reliability of the proposed procedure. A significant improvement in measurement of the EDS profile interfacial distance (DINT) has been achieved.

Relationships between systemic vascular resistance, blood rheology and nitric oxide in children with sickle cell anemia or sickle cell-hemoglobin C disease.

Vascular function has been found to be impaired in patients with sickle cell disease (SCD). The present study investigated the determinants of systemic vascular resistance in two main SCD syndromes in children: sickle cell anemia (SCA) and sickle cell-hemoglobin C disease (SCC). Nitric oxide metabolites (NOx), hematological, hemorheological, and hemodynamical parameters were investigated in 61 children with SCA and 49 children with SCC. While mean arterial pressure was not different between SCA and SCC children, systemic vascular resistance (SVR) was greater in SCC children. Although SVR and blood viscosity (ηb) were not correlated in SCC children, the increase of ηb (+18%) in SCC children compared to SCA children results in a greater mean SVR in this former group. SVR was positively correlated with ηb, hemoglobin (Hb) level and RBC deformability, and negatively with NOx level in SCA children. Multivariate linear regression model showed that both NOx and Hb levels were independently associated with SVR in SCA children. In SCC children, only NOx level was associated with SVR. In conclusion, vascular function of SCC children seems to better cope with higher ηb compared to SCA children. Since the occurrence of vaso-occlusive like complications are less frequent in SCC than in SCA children, this finding suggests a pathophysiological link between the vascular function alteration and these clinical manifestations. In addition, our results suggested that nitric oxide metabolism plays a key role in the regulation of SVR, both in SCA and SCC.

Prediction and limitation of polymer degradation in Environmental SEM.

Polymer materials degradation is a well-known limitation to their characterization in SEM. In this paper authors present an additional possibility for polymer imaging offered by the Environmental SEM applied to the PMMA with micrometric relief. As shown by the so-called double-scan procedure, increasing the pressure enables to delay the degradation of the polymer surface. To evaluate quantitatively this observation, the classical formula to calculate the electron dose is adapted to ESEM characteristic. It is shown first that pressure enables to decrease the electron dose and all that takes place as if the skirt electrons do not participate in the irradiation. Secondly this procedure allows to obtain the critical dose of topographic degradation, applied to the PMMA with micrometric relief D(C) was found to be 1.31 ± 0.28 Cm(-2). Finally it becomes then possible, knowing the D(C) for a given sample, to evaluate the limit of investigation without topographic surface degradation: for example, the maximal field of view (linked to the magnification) depending on the other parameters.

Pressure and scattering regime influence on the EDS profile resolution at a composite interface in environmental SEM.

Gas impact on the EDS profile resolution at the interface of composite interface resin/Al was investigated with two gaseous environments: helium and water vapor. Two main components of the global profile at the interface were investigated: the contrast of the profile and the spatial resolution. A complementary approach was developed by comparing gas nature impact versus the pressure and versus the scattering regime. The results show that the unscattered electron beam mainly governs EDS profile spatial resolution as long as the scattering regime is single or oligo scattering. Then for plural scattering, spatial resolution is dramatically degraded. In addition, the contrast is degraded since a gas is introduced, whatever the gas, the pressure and so the scattering regime. This approach would enable to better understand the respective contributions of the unscattered beam and the skirt and the influence of the gases nature on them.