Comptes rendus de l'Academie des sciences. Serie III, Sciences de la vie最新文献

The carbonic acid-base balance and the concentrations of Na and Cl were studied in 3 fluids, plasmatic, pericardial and peritoneal, sampled from 2 species of amphibians: Pleurodeles waltl and Xenopus laevis. In Pleurodeles the pericardial and peritoneal fluids are in a state of marked metabolic alkalosis, the carbonate alkalinity being up to 10 times higher in the serosal fluids than in the plasma, whereas PCO2's are very close in the 3 fluids. The Cl concentration is markedly lower in the serosal fluids than in the plasma. In Xenopus, the metabolic alkalosis of the serosal fluids also exists, but to a much lower extent than in Pleurodeles. These observations lead to further researches in the field of morphometry, physicochemistry and physiology.

In this experiment we compared the efficiency of fission neutrons of californium 252 at doses of 25 or 53 mGy in function of the dose rate. Two groups of male Sprague-Dawley rats were exposed at 100 or 420 days of age to fission neutrons with dose rates of 950 or 760 microGy/h for 26 or 33 h, and 2 other groups were irradiated over a year from 3 months to 15 months of age with dose rates of 3.58 or 7.72 microGy/h. The 4 groups of animals were compared with a control group of 501 rats. The reduction of effectiveness on cancer induction that we have previously shown at low dose rate with rats exposed to gamma rays or to alpha particles was not observed for low dose rate exposure with fission neutrons.

Ventricular myocytes isolated from the heart of adult rats were able do dedifferentiate within 7 days in primary culture using a medium containing 10% fetal calf serum. Calcium current was recorded in these cells by means of the whole cell patch clamp technique and compared to the calcium current obtained in freshly isolated myocytes and in non dedifferentiated cultured myocytes. In dedifferentiated cardiomyocytes, both T-type (ICa-T) and L-type (ICa-L) calcium current components were recorded while only L-type was observed in freshly isolated and in non dedifferentiated cultured myocytes. ICa-T was separated from ICa-L through its voltage dependence and its pharmacology. These results demonstrate that ICa-T which has been shown to be present at the neonatal stage but absent in adult ventricular cells can be reexpressed when adult cells were dedifferentiated in culture. Its possible involvement in development of cardiac cells and in electrophysiological properties leading to spontaneous activity is discussed.

Ethyl 4-methyloctanoate, which has already been described in Oryctes monoceros, has been identified, using extracts of effluvia collected from males, as being a major component of the male pheromone of O. rhinoceros. Field trials have been carried out in North Sumatra, Indonesia. Ethyl 4-methyloctanoate synthesized in the laboratory and released at 10 mg/d resulted in the capture of 6.8 insects per week per trap, whereas ethyl chrysanthemate (40 mg/d), an allelochemical compound once used as an attractant, only led to the capture of 0.3 insects, and the control none at all. The insects captured with the pheromone were 81% females, the majority being sexually mature. Discovery of this compound opens up new prospects for O. rhinoceros control.

Drosophila melanogaster populations are naturally infected by the Drosophila C virus (DCV). Ingestion of this non-hereditary virus early in the life-cycle has a positive effect. Demographic parameters measured on DCV-free and DCV-infected populations of the same genotype enabled us to compute the population growth rates (multiplication rates) by means of matrix models. The DCV-infected sample had a larger growth rate both for low and high larval densities. Since it is not possible to experiment on a mixed population where DCV-free and DCV-infected individuals live together, a model combining competition and contamination was used. Simulations showed that coexistence of free and infected animals can occur. Such a result leads us to question the relation between population growth rate and fitness.

A report is given of 8 cases of recurrent "idiopathic" abortions sharing in common the following features, unreported so far: (1) high uterine arterial impedance; (2) decrease in endometrial thickness, in spite of normal hormonal and endometrial cycle at biopsy; (3) a history of previous curettages. Such a syndrome could be consistent with the existence of a narrow peripheral symphysis of the uterine cavity, unaffecting its shape at hysterography.

We have reported earlier the cloning and the chromosomal localization of 2 GPX-encoding sequences expressed differentially within the mouse epididymis, gpx5 and gpx3. Here, we have mapped on the mouse chromosomes the third known murine GPX-encoding gene, the cytosolic GPX or gpx1. We have compared the degree of identity of the 3 GPX proteins, the respective organization of the 3 corresponding single copy genes and, using degenerated oligonucleotides designed in highly conserved domains of the proteins, we have analyzed the expression of GPX-encoding genes in the mouse epididymis as well as in control tissues known to express GPX proteins (the liver for GPX1 and the kidney for GPX3). The 3 genes characterized to date were found expressed in each of the tissues tested but in a highly tissue-restricted manner. Nucleotidic sequences comparisons were carried out on GPX-encoding sequences from various species and were used to draw a dendrogram. Phylogenetic evaluation of the sequence information, as well as the chromosomal localizations, suggest that the GPX genes have evolved by duplication events followed by random insertions from a single ancestral gene.

We have analyzed the cerebrospinal fluid (CSF) of 19 patients with multiple sclerosis (MS), 12 patients with degenerative dementia and 17 control patients using in vitro high resolution proton magnetic resonance spectroscopy (MRS) at 400 MHz. The CSF metabolic profile is slightly modified in MS patients (increased lactate and fructose concentrations, decreased creatinine and phenylalanine concentrations) and is not correlated with the intensity of the intrathecal inflammation. Proton MRS of CSF does not differentiate relapsing-remitting MS and primary progressive MS. We have not detected any specific abnormal resonance in native or lyophilized CSF. The CSF metabolic profile of demented patients is much more altered (increased concentration of lactate, pyruvate, alanine, lysine, valine, leucine-isoleucine, tyrosine, glutamine) and is in agreement with a brain oxidative metabolism impairment as already described in Alzheimer's disease. Unassigned abnormal but non specific or constant resonances have been detected on MR spectra of demented patients. CSF inositol concentration is also increased in the CSF of patients with Alzheimer's disease. In vitro high resolution proton MRS of the CSF constitutes a new and original way to explore CSF for the differential and/or early diagnosis of dementias, as a complement to in vivo proton cerebral MRS.