Proposition for the biochemical mechanism occurring in the sucrose isomerase active site.

Sucrose conversion by sucrose isomerase from Protaminobacter rubrum, Serratia plymuthica and Erwinia rhapontici was investigated in the presence of different monosaccharides in the reaction mixture. These conditions led to inhibitory effects and to glucosyl transfer of the glucose moiety of sucrose to the exogen monosaccharide. Comparison of the structure of the different inhibitors and acceptors has allowed us to suppose the binding of the sucrose molecule into the active site, and thereafter, to propose the possible biochemical reactions leading to the formation of different products from sucrose. This study also underlines the close homologies between these enzymes.

[Uni- or biventricular circulatory assist devices. Selection criteria and patients' follow-up, choice of device]. / Assistances uni- ou biventriculaires. Critères de sélection et de surveillance des patients, choix du dispositif.

Therapy of patients presenting with cardiogenic shock refractory to medical treatment can be undertaken with uni or biventricular circulatory assist devices. Pre implantation evaluation of patients is aimed at defining the etiology as well as the extent of uni versus biventricular heart failure, the possibility of recovery of myocardial function improvement of vital organ function and the possibility of cardiac transplantation. Circulatory assist devices must provide efficient support of the failing ventricles, allow recovery of myocardial function or cardiac transplantation under optimal circumstances. The choice of uni-biventricular support of total artificial heart is discussed as well as criteria useful in defining a therapeutic strategy.

[Influence of gender and size on parameters measured by signal-averaged electrocardiography in healthy subjects: preliminary study]. / Influence du sexe et de la taille sur les paramètres mesurés par électrocardiographie haute amplification chez les sujets sains; étude préliminaire.

The aim of this study was to determine the influence of electrocardiographic and biomorphometric factors on the parameters measured by signal averaged electrocardiography (SA-ECG) in normal subjects. The study population comprised 40 Caucasian students (20 men, 20 women). The SA-ECG measured 6 parameters: total duration of the averaged QRS, the root mean square of the voltage of the last 40 ms of the QRS (RMS 40) and the length duration of the terminal signal of under 40 microV (LAS), each parameter being measured with a band pass filter of 25 and 40 Hz. The echocardiographic recording included measurement of 12 parameters including left ventricular mass and ventricular volumes. Five morphological parameters were measured, including height, weight and body surface area. The duration of QRS measured with a 25 Hz band pass filter was significantly longer by 9.7 ms in men than in women (102.9 +/- 8.5 ms versus 93.2 +/- 8.1 ms; p < 0.001). Similarly, QRS duration measured with the 40 Hz band pass filter was longer in men by 11.4 ms than in women (102.1 +/- 9.6 ms versus 90.7 +/- 7.5 ms; p < 0.001). Multiple linear regression analyses showed that in both men and women, the duration of the QRS measured with either a 25 or 40 Hz band pass filter was correlated to size: the taller the subject, the longer the QRS duration. A negative correlation was observed between size and RMS 40 measured with both 25 and 40 Hz band pass filters: the taller the subject, the smaller the value of RMS 40.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficiency of fatty acid synthesis by oleaginous yeasts: Prediction of yield and fatty acid cell content from consumed C/N ratio by a simple method.

In nitrogen-limited media, growth and fatty acid formation by the oleaginous yeast Rhodotorula glutinis, i.e., yield and fatty acid cell content, have been characterized regarding carbon and nitrogen availabilities. It was shown that the formation of fatty acid free biomass was limited by nitrogen availability, whereas the fatty acid production was directly dependent on the consumed C/N ratio. According to these observations, the fraction of substrate consumed for fatty acid synthesis was estimated by using a simple method based on the actual yields, i.e., the mass of carbon source strictly converted into fatty acids and fatty acid free biomass. From these results, relationships were established allowing to predict in a simple and performing manner the maximal attainable fatty acid cell content and yield from the available carbon and nitrogen. These relationships were validated by using experimental data obtained by various authors with different yeast strains, and the proposed method was compared to the energetic and mass balance method previously described.