[Sodium restriction prevents cardiovascular remodeling associated with insulin-resistance in the rat]. / La restriction sodée prévient le remodelage cardiovasculaire dans l'insulinorésistance chez le rat.

AIM OF THE STUDY: In the present work, the objective was to evaluate the influence of a dietary sodium restriction on cardiovascular morphology changes associated with insulin-resistance. ANIMALS AND PROTOCOL: At 8 weeks of age, rats were fed for 12 weeks a 60%-fructose diet containing a regular sodium content (0.64%) or totally lacking in sodium chloride (<0.01%). A group of rats fed a wheat starch-based diet with regular sodium content served as control group. RESULTS: Elevated HOMA index and plasma insulin confirm the presence of insulin-resistance in fructose-fed rats. Concomitantly, an increase in cardiac mass and in cardiac collagen (Sirius red staining) was detected without obvious change in arterial pressure or cardiac aldosterone synthase mRNA expression. In addition, cross-sectional area of the carotid artery was higher in fructose-fed rats. Production of superoxide anion, equated with dihydroethidium (DHE) staining, was enhanced in cardiac tissue of rats with insulin-resistance. Withdrawal of sodium from the fructose diet prevented all the cardiovascular effects of fructose consumption, including DHE staining. CONCLUSION: These results are in favor of the participation of oxidative stress normalization in the beneficial influence of dietary sodium deprivation on cardiovascular remodeling in this model of insulin-resistance in rats.

[Oxydative stress and beneficial effect of sodium restriction on kidney damage associated with insulin resistance in rats]. / Stress oxydant et effets bénéfiques rénaux de la restriction sodée dans l'insulinorésistance chez le rat.

The aim of this work was to evaluate the influence of dietary sodium restriction on metabolic and renal changes associated with insulin resistance. At 8 weeks of age, rats received either a diet containing 60% fructose with or without sodium or a standard diet for 12 weeks. The insulin resistance and albuminuria induced by the high fructose diet were associated with a fibrosis and increase in oxidative stress in the kidney. The low salt diet prevented insulin resistance, renal fibrosis and albuminuria induced by the fructose diet. These beneficial effects on the kidney were associated with a decrease in kidney NADPH oxidase activity. Oxidative status is probably one of the major targets of the favourable effect of salt restriction on renal changes associated with insulin resistance, without excluding the involvement of other mechanisms.

Carbon monoxide pollution impairs myocardial perfusion reserve: implication of coronary endothelial dysfunction.

Chronic exposure to simulated urban CO pollution is reported to be associated with cardiac dysfunction. Despite the potential implication of myocardial perfusion alteration in the pathophysiology of CO pollution, the underlying mechanisms remain today still unknown. Therefore, the aim of this work was to evaluate the effects of prolonged exposure to simulated urban CO pollution on the regulation of myocardial perfusion. Cardiac hemodynamics and myocardial perfusion were assessed under basal conditions and during the infusion of a ß-Adrenergic agonist. The effects of CO exposure on capillary density, coronary endothelium-dependent vasodilatation, eNOS expression and eNOS uncoupling were also evaluated. Our main results were that prolonged CO exposure was associated with a blunted myocardial perfusion response to a physiological stress responsible for an altered contractile reserve. The impairment of myocardial perfusion reserve was not accounted for a reduced capillary density but rather by an alteration in coronary endothelium-dependent vasorelaxation (-45% of maximal relaxation to ACh). In addition, though chronic CO exposure did not change eNOS expression, it significantly increased eNOS uncoupling. Therefore, the present work underlines the fact that chronic CO exposure, at levels found in urban air pollution, is associated with reduced myocardial perfusion reserve. This phenomenon is explained at the coronary-vessel level by deleterious effects of CO exposure on the endothelium NO-dependent vasorelaxation via eNOS uncoupling.

[Renin-angiotensin system inhibition and cardiac and renal alteration induced by a high sodium diet in rat]. / Inhibition du système rénine-angiotensine et altérations cardiaque et rénale induites par une consommation excessive de sodium chez le rat.

BACKGROUND: The present study was designed to assess the influence of losartan on cardiac hypertrophy and albuminuria associated with early high sodium feeding in rats and to compare it to an angiotensin-converting enzyme inhibitor, enalapril, effect. METHODS: Male Sprague-Dawley rats received a regular diet (0.8% NaCl, NS, n=7), or high sodium diet (8% NaCl, HS, n=21) from weaning for 8 weeks. After 4 weeks of diet, two HS groups were treated or not for 4 weeks with losartan or enalapril (30 and 10 mg/kg(-1) x day(-1) respectively, n=7 in each). Food and water consumption, body weight, urinary volume and urinary excretion of sodium, potassium and albumin were measured at the end of treatment as well as arterial pressure (anesthetized rats), heart and kidney weight. RESULTS: Eight weeks after weaning, heart weight index and albuminuria were significantly higher in HS control group when compared to the control NS group without change of arterial pressure. Treatment with losartan or enalapril had no effect either on arterial pressure or cardio-renal alterations.

[I/D gene polymorphism of the angiotensin-converting enzyme and left ventricular hypertrophy. Response to converting enzyme inhibitors]. / Polymorphisme I/D du gène de l'enzyme de conversion de l'angiotensine et hypertrophie ventriculaire gauche. Réponse aux inhibiteurs de l'enzyme de conversion.

BACKGROUND: The present study was designed to assess whether the angiotensin-converting enzyme (ACE) gene I/D polymorphism influence the ACE inhibitors effect on the regression of left ventricular hypertrophy. METHODS: Sixty hypertensive subjects never treated by antihypertensive drugs, aged 46 +/- 11 years, were included in the study. Follow-up with ACE inhibitor treatment was 60 +/- 26 months. Genotypes for ACE I/D polymorphism (DD, ID or II) were determined by PCR. The left ventricular mass index (LVMI) was assessed by two-dimensional directed M-mode echocardiography. RESULTS: ACE genotype distribution was in agreement with the Hardy-Weinberg equilibrium: 21 patients had the DD genotype, 29 were ID, and 10 were II. At baseline, age, systolic arterial pressure and LVMI didn't differ on the basis of genotype. Body mass index was significantly higher in II than in ID and DD groups. Regression of LVMI with ACE inhibitor treatment was similar in the 3 genotypes (-8.9%, -0.6%, -12.1% in DD, ID and II groups respectively). In addition, decrease of systolic arterial pressure was identical in 3 groups. CONCLUSION: ACE gene I/D polymorphism seems not to influence regression of left ventricular hypertrophy by ACE inhibitors in essential hypertension.

[Wegener's granulomatosis in the elderly patient]. / Granulomatose de Wegener du sujet âgé.

PURPOSE: To determine aged-related variations in clinical and biological presentation and outcome in Wegener's granulomatosis. METHODS: In a retrospective cohort study of 35 patients with a diagnosis of Wegener's granulomatosis, 24 patients (69%) younger than 60 years of age and 11 (31%) aged 60 years or older were compared for clinical and biological characteristics. RESULTS: Clinical presentation was the same in the two groups; lymphopenia was more common in the elderly group (P > 0.05). Despite a similar treatment regime, outcome was significantly worse for the elderly group (> or = 60 years), with a mortality rate of 36% versus 8% in the control group. Mortality was essentially due to delayed infectious complications, raising the problem of a less intensive immunosuppressive treatment after remission.