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Biomedical subjects

S Roux

Publications and source records attributed to S Roux.

At least 127 records · Page 7Linked to original sources
PubMed1993

Influence of congestive heart failure on endothelin levels and receptors in rabbits.

Congestive heart failure, both in man and in animals is associated with an increased plasma level of endothelin. To investigate further the potential role of the endothelin system, we designed a study to determine the effect of experimental congestive heart failure (CHF) on plasma and tissue immunoreactive-endothelin (irET) and on the density and affinity of endothelin-1 receptors in the heart and kidney. For this purpose, CHF was induced in rabbits by combined aortic valvular insufficiency and stenosis. When CHF was established, plasma and tissue irET levels were measured by radioimmunoassay and density and affinity of endothelin-1 receptors were measured by binding assay on tissue homogenates. Compared to control rabbits, plasma irET was significantly elevated in rabbits with CHF [1.04 +/- 0.15 vs. 0.04 +/- 0.01 fmol/ml, P < 0.001]. Tissue irET concentrations in ventricles and kidney were roughly 4 orders of magnitude higher than plasma concentrations. CHF decreased the tissue irET levels in left ventricle and kidney by 32 and 46%, respectively (P < 0.01), whereas CHF increased it by 58% in the right ventricle (P < 0.005). The density of ET-1 receptors was decreased in the right and left ventricles and in kidneys by 26, 36, and 61%, respectively (P < 0.05). Receptor affinity remained unchanged in response to CHF in both ventricles, whereas it increased in kidney [Kd (pM); 154 +/- 17 vs. 99 +/- 9, P < 0.01]. Thus, this study demonstrates that experimental CHF is not only characterized by elevated plasma irET levels but also by a decrease in tissue irET concentrations in the left ventricle and kidney, and by a down-regulation of ET-1 receptors both in the heart and kidney. Functional consequences of these changes need to be determined.

Animals↗
PubMed1993

Stretch-induced inositol trisphosphate and tetrakisphosphate production in rat cardiomyocytes.

The kinetics and signal transduction of inositol phosphate production were studied after a 20% stretch of neonatal rat cardiomyocytes in culture. Inositol trisphosphate (IP3) production was increased by 41% above control after 10-20 s of cellular stretch but returned to control after 120 s of stretch. The increase in IP3 was potentiated in high K+ medium and was inhibited by pertussis toxin, suggesting the existence of a pertussis toxin-sensitive G protein in signal transduction. Ion-pair HPLC analysis of cell extracts stretched for 20 s showed an increase in both IP3 isomers, mostly 1,4,5-IP3 (+66%) with a weak increase in IP4 (+10%), whereas 120 s stretch induced an increase in IP4 (+26% above control) associated with a decrease of 1,4,5-IP3 isomer as compared with 20 s stretch. It is concluded that the progressive increase in IP4 production associated with an early rise in IP3 after stretching myocardial cells may be a factor inducing the length-dependent activation of cardiac muscle through a modulation of intracellular free calcium concentration.

Animals↗
PubMed1993

Auditory stimulus intensity responses and frontal midline theta rhythm.

The influence of stimulus intensity on the N1 component of auditory evoked potentials recorded at fronto-central sites was investigated in respect to the spectral components of the EEG recorded at Cz, Fz and Oz. The study was performed on 14 healthy adult subjects. The only EEG frequency bandwidth that was strongly correlated with the N1 amplitude-intensity slope was the theta rhythm, particularly the 5-7 Hz frequencies recorded at Cz and Fz. This frequency bandwidth corresponds to the previously described frontal midline theta rhythm related to performance of tests that require continuous concentration of attention. Our results show that the steeper the slope, the greater the amount of Fm theta. This suggests that the interindividual differences in the N1 amplitude/intensity slope could be related to interindividual differences in attentional readiness toward the auditory stimuli, even when delivered in "passive" conditions.

Adult↗
PubMed1993

Influence of the status of the renin-angiotensin system on the effect of cilazapril on neointima formation after vascular injury in rats.

BACKGROUND: Angiotensin converting enzyme (ACE) inhibition has been shown to prevent neointima formation after vascular injury in rats. However, clinical results evaluating restenosis after angioplasty have been negative. The goal of the present study was to evaluate the influence of the renin-angiotensin system (RAS) status on the effect of ACE inhibition on neointima formation. METHODS AND RESULTS: Arterial injury was produced by ballooning the left carotid artery of rats, and neointima formation was evaluated by morphometry 2 weeks after ballooning. The effects of cilazapril were assessed in four experimental groups: normotensive rats, spontaneously hypertensive rats, hypertensive rats with a renal artery stenosis induced by clipping (two-kidney, one-clip rats), and hypertensive rats with uninephrectomy, high salt intake, and administration of deoxycorticosterone (DOCA). In parallel groups of rats, measurement of plasma renin activity was made in order to characterize (at least at the plasma level) the status of the RAS. As expected, renal artery stenosis markedly increased plasma renin activity, and DOCA decreased it to undetectable levels. Cilazapril had a marked preventive effect on neointima formation in normotensive rats, spontaneously hypertensive rats, and two-kidney, one-clip rats but was ineffective in DOCA rats. CONCLUSIONS: We conclude that the status of the RAS has a major influence on the effect of cilazapril on neointima formation after vascular injury.

Animals↗
PubMed1993

Ro 44-9883, a new nonpeptide glycoprotein IIb/IIIa antagonist, prevents platelet loss during experimental cardiopulmonary bypass.

Extensive contact between blood and artificial surfaces causes platelet activation and depletion. The aim of the study was to test the efficacy of Ro 44-9883, a new nonpeptide, reversible, glycoprotein IIb/IIIa antagonist in preventing platelet count drop in dogs undergoing cardiopulmonary bypass during 2 hours. Twenty-two heparinized dogs were divided into three groups, one control group (n = 9) not treated, one group treated with a low dose of Ro 44-9883 (145 micrograms/kg intravenously, n = 6), and one group treated with a high dose of Ro 44-9883 (870 micrograms/kg intravenously, n = 7). In the control group, platelet counts declined to 53% +/- 15% of initial levels at the start of cardiopulmonary bypass and remained lower than 80% of initial levels during follow-up. Platelet count drop was completely prevented in the Ro 44-9883 high-dose group, whereas it was only partially prevented in the low-dose group. Blood loss was similar in the three groups despite the fact that bleeding times were longer in the Ro 44-9883 high-dose group than in the control group. We conclude that Ro 44-9883, together with heparin as a standard anticoagulant, is highly effective in preventing platelet count drop during cardiopulmonary bypass without causing excessive bleeding.

Acetates↗
PubMed1992

Unimodal and crossmodal reactivity in autism: presence of auditory evoked responses and effect of the repetition of auditory stimuli.

Using auditory evoked responses, this work compares the reactivities to unimodal and crossmodal stimuli and the main neurocognitive functions most often disturbed in autism. With the aim of testing the hypothesis that the deficit in the ability to form crossmodal associations in autism is linked to a cognitive abnormality, auditory evoked responses to simple and to crossmodal (auditivo-visual) stimuli were recorded in 30 autistic children and compared with those of 30 normal and 30 mentally retarded children. Relationships between electrophysiological reactivity and neurocognitive functions showed that the cognitive deficit in the ability to maintain crossmodal associations is preceded by a more elementary perceptive abnormality in autistic children.

Acoustic Stimulation↗
PubMed1992

Effects of aspirin on coronary reocclusion and recurrent ischemia after thrombolysis: a meta-analysis.

Reocclusion of infarct-related coronary arteries within 2 weeks of thrombolytic therapy varies from 5% to 45% and neither clinical nor angiographic variables have been proved to be predictive of reocclusion. The goal of the present study was to evaluate whether aspirin could prevent coronary reocclusion and recurrent ischemia after thrombolysis. For this purpose, a meta-analysis including 32 studies was performed. Although the studies showed very similar demographic data, the reocclusion rate assessed by angiography in 419 patients treated with aspirin was 11% compared with 25% in 513 patients without aspirin therapy (p less than 0.001). Recurrent ischemic events were present in 25% of 2,977 patients treated with aspirin and 41% of 721 patients treated without aspirin (p less than 0.001). The effect of aspirin was similar in trials with either streptokinase or recombinant tissue-type plasminogen activator (rt-PA). Thus, aspirin in the presence of heparin might prevent coronary reocclusion after thrombolysis.

Angina Pectoris↗
PubMed1992

Sensitivity and specificity of the Behavioral Summarized Evaluation (BSE) for the assessment of autistic behaviors.

The Behavior Summarized Evaluation (BSE), developed for the assessment of autistic behavior, was specifically designed to evaluate the severity of behavioral problems in autistic children involved in bioclinical and therapeutic studies. The reliability studies and the factorial analysis of this scale have been previously published. The present paper examines the effectiveness of the BSE to discriminate 58 autistic from 58 nonautistic mentally retarded children. The BSE clearly separated the two samples of children. A most efficient combination of 8 items emerged from the stepwise item selection procedure. The between-group differences were highest on 4 items, indicating that the most particular pattern in autistic compared to nonautistic children could be the association of autistic withdrawal and stereotypic behaviors. Our findings suggest that the BSE could help in the detection and evaluation of autistic developmental deviance. Implications for further research are discussed.

Autistic Disorder↗
PubMed1992

Validity and reliability of the infant behavioral summarized evaluation (IBSE): a rating scale for the assessment of young children with autism and developmental disorders.

The Infant Behavioral Summarized Evaluation (IBSE) is a rating scale adapted from the Behavioral Summarized Evaluation (BSE) and specifically related to the assessment of behaviors of young children having autistic disorders. Content validity and reliability studies described in the paper were made from behavior ratings of videotapes for 89 children aged from 6 to 48 months. Results show a significant group of 19 items including some characteristic early autistic behaviors (communicative and social abnormalities) and some that are less commonly described in the syndrome (attentional, perceptive, and adaptive disorders). The value of the use of this scale for clinicians and professionals involved in behavioral evaluations and treatment of young children with developmental disorders and the necessity for further psychometric investigations are discussed.

Autistic Disorder↗
PubMed1992

Electrophysiological evidence of different abilities to form cross-modal associations in children with autistic behavior.

This study evaluates the amplitudes of auditory evoked responses and the variability of evoked responses, using a signal-to-noise ratio (SNR) method applied to individual evoked potential in a cross-modal (sound and light) association paradigm in 17 children with autistic behavior matched for sex and chronological age with normal children. Auditory evoked responses were smaller in children with autistic behavior than in normal children. The modifications of amplitudes and of SNR during cross-modal associations allowed the separation of children with autistic behavior into 3 subgroups who presented different patterns of ability to form cross-modal associations. These 3 subgroups of children presented different clinical profiles demonstrating that the differences observed in the ability to form cross-modal associations can be related to differences in the main psychophysiological functions such as attention, intention, motility, association, contact and communication.

Acoustic Stimulation↗
PubMed1992

Isoproterenol impairs the rat coronary vasculature: effects of angiotensin-converting enzyme inhibition.

The purpose of the present study was to evaluate whether in addition to its myocardial effects, chronic beta-adrenergic stimulation with isoproterenol could modify the coronary vasculature. For this purpose, rats were treated for 2 weeks with isoproterenol, and the hearts were isolated for determination of the minimal coronary vascular resistance under maximal vasodilation and then perfused-fixed for morphometry of the coronary arteries. In addition, because isoproterenol stimulates the renin-angiotensin system (RAS), the effects of angiotensin-converting enzyme (ACE) inhibition on the coronary vasculature were assessed. Isoproterenol increased heart weight by 65% and minimal coronary resistance by 55%. This effect was associated with medial thickening in intermediate (32%) and large coronary arterioles (26%). Cilazapril, a long-acting ACE inhibitor, completely prevented the medial thickening induced by isoproterenol and normalized the minimal coronary resistance. We conclude that impairment of the rat coronary vasculature induced by chronic beta-adrenergic stimulation might be in part mediated by activation of the RAS.

Angiotensin-Converting Enzyme Inhibitors↗