Dépistage de l’ischémie myocardique par l’échocardiographie de stress à la dobutamine chez le diabétique de type 2 à haut risque cardiovasculaire au Sénégal

Introduction

Diabetes is a major risk factor for coronary artery disease witch may develop insidiously. Several non-invasive methods are used to detect silent myocardial ischaemia, especially in diabetic patients at high cardiovascular risk. We project to screen, by dobutamine stress echocardiography, silent myocardial ischaemia in type 2 diabetics in Senegal.

Methodology

We randomly recruited in hospital in Senegal type 2 diabetics aged at least 40 years and a dobutamine stress echocardiography was performed in those selected according to the French Society of Cardiology and the French Language Association for the Study of Diabetes and Metabolic Diseases.

Results

Dobutamine stress echocardiography was performed in 79 diabetics at high cardiovascular risk, including 56 women. The average age was 58.8 ± 11.8 years. The exam was positive in 67.1% of cases (53/79), with a predominance of motion abnormalities in anterior territory (83%). Cardiovascular risk factors associated with positivity of test were microalbuminuria (p = 0.0001), inactivity (p = 0.0001), dyslipidemia (p = 0.0002), arterial hypertension (p = 0.001), smoking (0.003) and male sex (p = 0.004).

Conclusion

In Africa, dobutamine stress echocardiography has the advantage of its accessibility and its feasibility. Early detection of silent myocardial ischaemia in diabetics at high risk could optimize their care.     

HIF-2alpha-haploinsufficient mice have blunted retinal neovascularization due to impaired expression of a proangiogenic gene battery

PURPOSE: To characterize the effect of HIF-2alpha haploinsufficiency on retinal neovascularization and angiogenic signaling in neonatal mice. METHODS: Retinal samples were obtained from HIF-2alpha-haploinsufficient (Epas1+/-) and wild-type (Epas1+/+) neonatal mice subjected to an oxygen-induced retinopathy (OIR) protocol. Histologic and molecular studies were performed immediately, 12 hours, or 5 days after initiation of the hypoxia phase of the OIR protocol. Molecular profiling was performed in mouse brain endothelial cells maintained in normoxia or hypoxia. Transfection studies assessed the response of isolated promoter regions from proangiogenic genes to HIF-1alpha or -2alpha overexpression. RESULTS: Epas1+/- mice exhibited no significant differences in retinal vasculature during normal development but had reduced retinal neovascularization in an OIR protocol. Multiple proangiogenic factors were induced during the hypoxia phase in Epas1+/+ OIR retinal samples, whereas Epas1+/- OIR retinal samples had absent or blunted induction of these same factors. Several, but not all, proangiogenic factors were induced in mouse brain endothelial cells after hypoxia. In transfection assays, most proangiogenic promoter regions were preferentially activated by HIF-2alpha relative to HIF-1alpha. CONCLUSIONS: HIF-2alpha deficiency results in reduced neovascularization and blunted inducibility of multiple proangiogenic factors in the retinas of mice with OIR. The authors propose that HIF-2alpha is a master regulator of proangiogenic factors in retinal vascular endothelial cells, the predominant cell type of the retina in which HIF-2alpha is expressed. Future studies will address whether the molecular and functional roles for HIF-2alpha identified from these studies can be generalized to other pathophysiological states involving neovascularization.     

Effect of Oat β-Glucan on Affective and Physical Feeling States in Healthy Adults: Evidence for Reduced Headache,Fatigue, Anxiety and Limb/Joint Pains

The gastrointestinal (GI) side-effects of dietary fibers are recognized, but less is known about their effects on non-GI symptoms. We assessed non-GI symptoms in a trial of the LDL-cholesterol lowering effect of oat β-glucan (OBG). Participants (n = 207) with borderline high LDL-cholesterol were randomized to an OBG (1 g OBG, n = 104, n = 96 analyzed) or Control (n = 103, n = 95 analyzed) beverage 3-times daily for 4 weeks. At screening, baseline, 2 weeks and 4 weeks participants rated the severity of 16 non-GI symptoms as none, mild, moderate or severe. The occurrence and severity (more or less severe than pre-treatment) were compared using chi-squared and Fisher’s exact test, respectively. During OBG treatment, the occurrence of exhaustion and fatigue decreased versus baseline (p < 0.05). The severity of headache (2 weeks, p = 0.032), anxiety (2 weeks p = 0.059) and feeling cold (4 weeks, p = 0.040) were less on OBG than Control. The severity of fatigue and hot flashes at 4 weeks, limb/joint pain at 2 weeks and difficulty concentrating at both times decreased on OBG versus baseline. High serum c-reactive-protein and changes in c-reactive-protein, oxidized-LDL, and GI-symptom severity were associated with the occurrence and severity of several non-GI symptoms. These data provide preliminary, hypothesis-generating evidence that OBG may reduce several non-GI symptoms in healthy adults.     

Validity of impedance-based equations for the prediction of total body water as measured by deuterium dilution in African women

BACKGROUND: Little information is available on the validity of simple and indirect body-composition methods in non-Western populations. Equations for predicting body composition are population-specific, and body composition differs between blacks and whites. OBJECTIVE: We tested the hypothesis that the validity of equations for predicting total body water (TBW) from bioelectrical impedance analysis measurements is likely to depend on the racial background of the group from which the equations were derived. DESIGN: The hypothesis was tested by comparing, in 36 African women, TBW values measured by deuterium dilution with those predicted by 23 equations developed in white, African American, or African subjects. These cross-validations in our African sample were also compared, whenever possible, with results from other studies in black subjects. RESULTS: Errors in predicting TBW showed acceptable values (1.3-1.9 kg) in all cases, whereas a large range of bias (0.2-6.1 kg) was observed independently of the ethnic origin of the sample from which the equations were derived. Three equations (2 from whites and 1 from blacks) showed nonsignificant bias and could be used in Africans. In all other cases, we observed either an overestimation or underestimation of TBW with variable bias values, regardless of racial background, yielding no clear trend for validity as a function of ethnic origin. CONCLUSIONS: The findings of this cross-validation study emphasize the need for further fundamental research to explore the causes of the poor validity of TBW prediction equations across populations rather than the need to develop new prediction equations for use in Africa.     

Use of hand-to-hand impedancemetry to predict body composition of African women as measured by air displacement plethysmography

OBJECTIVES: To test the validity of a simple, rapid, field-adapted, portable hand-held impedancemeter (HHI) for the estimation of lean body mass (LBM) and percentage body fat (%BF) in African women, and to develop specific predictive equations. DESIGN: Cross-sectional observational study. SETTINGS: Dakar, the capital city of Senegal, West Africa. SUBJECTS: A total sample of 146 women volunteered. Their mean age was of 31.0 y (s.d. 9.1), weight 60.9 kg (s.d. 13.1) and BMI 22.6 kg/m(2) (s.d. 4.5). METHODS: Body composition values estimated by HHI were compared to those measured by whole body densitometry performed by air displacement plethysmography (ADP). The specific density of LBM in black subjects was taken into account for the calculation of %BF from body density. RESULTS:: Estimations from HHI showed a large bias (mean difference) of 5.6 kg LBM (P<10(-4)) and -8.8 %BF (P<10(-4)) and errors (s.d. of the bias) of 2.6 kg LBM and 3.7 %BF. In order to correct for the bias, specific predictive equations were developed. With the HHI result as a single predictor, error values were of 1.9 kg LBM and 3.7 %BF in the prediction group (n=100), and of 2.2 kg LBM and 3.6 %BF in the cross-validation group (n=46). Addition of anthropometrical predictors was not necessary. CONCLUSIONS: The HHI analyser significantly overestimated LBM and underestimated %BF in African women. After correction for the bias, the body compartments could easily be estimated in African women by using the HHI result in an appropriate prediction equation with a good precision. It remains to be seen whether a combination of arm and leg impedancemetry in order to take into account lower limbs would further improve the prediction of body composition in Africans.     

Body composition predicted from skinfolds in African women: a cross-validation study using air-displacement plethysmography and a black-specific equation

Skinfold thickness (SF) measurements are commonly used for the indirect assessment of body composition. It is necessary to know how large the bias is when using Caucasian SF-based prediction equations Africans, as no specific equations exist. Our first aim was to test the validity of the equation of Durnin & Womersley for predicting body density from SF in Africans. The second aim was to determine the effect of calculating percentage body fat (%BF) from body density using a black-specific formula rather than the Siri equation, thus taking into account the higher fat-free mass (FFM) density in blacks than in whites. A total of 196 African women volunteered. Mean age was 29.5 (sd 8.7) years and mean BMI was 22.5 (sd 4.6) kg/m2. We compared body density values predicted from SF with those measured by air-displacement plethysmography, and %BF values obtained from body density using the Siri equation or the black-specific calculation. The bias (reference minus prediction) was 0.0100 kg/cm3 in body density (P<10(-4)) and 6.5 % BF (P<10(-4)), and the error (sd of the bias) 0.0097 kg/l and 4.5 % BF. With the black-specific equation, the bias was reduced by 1.9 % BF, while error remained similar. As the %BF prediction required an SF-based equation followed by a body density-based calculation, the lack of validity we observed in Africans may be due to known differences between blacks and whites in the distribution of subcutaneous adipose tissue and, as demonstrated, in the FFM density. Equations thus need to be established using SF values specific to Africans.