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M F Vincent

Publications and source records attributed to M F Vincent.

66 records · Page 4Linked to original sources
PubMed1983

Effects of a cardioselective beta 1 partial agonist (corwin) on left ventricular function and myocardial metabolism in patients with previous myocardial infarction.

Corwin is a new selective beta 1 partial agonist, able to stabilize the beta 1 adrenoceptors at approximately 43% of their maximal activity. The aim of the study was to determine the effects of this agent in patients with coronary artery disease (CAD) and previous myocardial infarction (MI). In a first group of 14 patients, corwin increased significantly the peak (+)dP/dt (+35%; p less than 0.005), the global ejection fraction, and the ejection fraction of abnormally contracting segments (from 20 +/- 18 to 26 +/- 19%; p less than 0.02). Corwin also induced significant decreases in mean systolic (-8%; p less than 0.05) and mean diastolic (-38%; p less than 0.001) wall stress and accelerated the relaxation rate. In a second group of 11 patients, a metabolic study indicated that neither myocardial oxygen consumption (15 +/- 7 versus 15 +/- 7 ml/min; difference not significant) nor lactate extraction was modified by the drug. In this group, increases in peak (+)dP/dt, acceleration in ventricular relaxation (-8 ms in time constant of isovolumic pressure decrease; p less than 0.01), and decreases in left ventricular end-diastolic pressure also were noted after administration of corwin, both under basal conditions and during a cold pressor test. In conclusion, corwin is a positive inotrope which, in patients with CAD and left ventricular dysfunction, improves left ventricular systolic and diastolic function without inducing myocardial ischemia.

Adrenergic beta-Agonists↗
PubMed1983

[The place of urinary cytology in the diagnosis of urothelial tumors].

A cytologic study was done in three groups of patients, either for screening purposes or for the follow up of vesical tumors already treated by transurethral resection or cystectomy. The reliability of urinary cytology is closely related to the degree of tumor anaplasia (81,8% positive cytology in grade III tumors). When a cytologic and cystoscopic follow-up is done, the results of these two methods are in agreement in 60% of the cases. In the follow up of patients already treated for vesical tumors, the association of cystoscopy and cytology increases the discovery of recurrences by 40%. The persistence of isolated positive cytologies is indicative of highly malignant lesions (grade III). In cystectomized patients, a close correlation exists between the histologic grade and the positivity of the cytologic survey. A cytologic follow up after cystectomy helps to discover a greater number of urethral recurrences.

Carcinoma in Situ↗
PubMed1982

The pathway of adenine nucleotide catabolism and its control in isolated rat hepatocytes subjected to anoxia.

1. The breakdown of the adenine nucleotide pool provoked by the replacement of the O(2)/CO(2) gas phase by N(2)/CO(2) was studied in isolated rat hepatocytes with the purpose of defining the pathway of the catabolism of AMP in anoxic conditions. 2. Approx. 40% of the adenine nucleotide pool was lost after 40-60 min of anoxia. In hepatocytes from fed rats there was a slow disappearance of ATP. This is explained by the presence of glycogen stores, allowing the generation of ATP by anaerobic glycolysis. In hepatocytes from 24h-starved rats, ATP almost completely disappeared within 5 min, and was partly replaced by an accumulation of AMP. This indicates that another mechanism protects the adenine nucleotide pool in the starved state. In both conditions, the loss of adenine nucleotides was mainly accounted for by an accumulation of uric acid, owing to the oxygen-dependence of urate oxidase. 3. Incubation of the hepatocytes before the suppression of O(2) with coformycin at concentrations known to inhibit selectively adenosine deaminase did not result in an accumulation of adenosine and did not influence the formation of uric acid. This indicates that the degradation of AMP does not proceed by way of 5'-nucleotidase under these conditions. In the presence of coformycin at concentrations which are inhibitory to AMP deaminase, however, the formation of uric acid was nearly suppressed, demonstrating that the initial degradation of AMP was catalysed by the latter enzyme. 4. The accumulation of AMP in the starved state can be explained by the pronounced decrease in ATP, the major stimulator of AMP deaminase, and the enhanced increase in P(i), one of its physiological inhibitors. The modifications of these effectors can also explain the increased inhibition of the cytoplasmic 5'-nucleotidase, shown by the accumulation of IMP in the absence of coformycin, in hepatocytes from starved rats. 5. Reoxygenation of the hepatocytes after 20 min of anoxia induced a prompt regeneration of ATP, which reached concentrations equal to the pre-existing concentration of AMP. 6. No explanation was found for the accumulation of IMP observed after preincubation of the hepatocytes with 0.1mum-coformycin, since the activities of the IMP-metabolizing enzymes were not influenced by this inosine analogue.

Adenine Nucleotides↗
PubMed1981

[Kurloff's thymic inclusion : action on rat gonads in culture].

Thymic and splenic extracts rich in FOA-KURLOFF (F.K.) body cells, obtained from guinea-pigs treated with oestrogen, were added to rat testis or ovaries in culture. Controls were prepared with extracts from thymus and spleen of non treated animals and from kidneys of treated or non treated animals. After five hours the level of sexual hormones and the germinal cells were studied. The F.K. substance has no effect on germinal cells and on progesterone and testosterone secretion. The F.K. substance induces a significative decrease of oestrogen secretion. In an other paper we established that F.K. bodies induced a hyperactivity of internal theca folliculi and of ovarian interstitial cells. It is a false image of activity in connection with a hypersecretion of FSH. The F.K. substance inhibits oestrogen synthesis.

Animals↗
PubMed1979

Light-induced conductivity changes in purple membrane suspensions.

Small light-induced changes in the conductivity of light-adapted purple membrane suspended in strong electrolyte solutions were detected. The method used involved modulated light and a phase sensitive detector and it allowed us to detect accurately changes as small as 0.0001% in the conductivity of the suspension. The light-induced conductivity changes turned out to be composed of at least two different event: a small fast increase in conductivity (tau approximately 2 ms) followed by a slower and larger decrease in this parameter (tau = 70 ms-80 ms). The effects of pH and temperature on these changes were studied. Both events reached maximal values around neutral pH and approached zero at both high and low pH's. Heating the suspension decreased the photoconductivity change and Arrhenius plots of the data showed breaks around 31 degrees C. It is suggested that the conductivity changes reflect changes in the surface charge of the membrane and can be used to follow the kinetics of the conformational changes occurring in the system.

Bacteriorhodopsins↗
PubMedDate not supplied

[The value of xamoterol in moderate ischemic cardiac insufficiency].

Xamoterol is a partial beta-1 adrenergic agonist capable of stabilising the beta-1 receptor to 43% of their maximal activity. Xamoterol was administered to 10 patients with moderate ischaemic heart failure at an oral dose of 200 mg twice a day. After 3 months, there was an improvement in left ventricular function: 28% reduction in the end-diastolic pressure (p less than 0.01), 12% reduction in ventricular volume (p less than 0.05) with a marked increase in the inotropic state. The exercise tolerance was also increased (+ 30 watt; p less than 0.05) and several indices suggest an improvement in myocardial metabolism. In conclusion, xamoterol is a positive inotrope which does not present the phenomenon of tachyphylaxis during the prolonged administration.

Adrenergic beta-Agonists↗