Search PubMed⌕ Search

Biomedical subjects

G Gras

Publications and source records attributed to G Gras.

At least 55 records · Page 3Linked to original sources
PubMed1982

[Effect of temephos on the acetylcholinesterase activity of the brain of Tilapia guineensis. 2: Experimental study of 24-hour exposure to the toxic compound].

The exposition of the Tilapia guineensis to concentrations used in the field to destroy the simulium larvae in their aquatic biotopes is 0,05 mg/l/10 minutes. The authors have previously remarked a significant lowering of acetylcholinesterasic brain activity in this fish. In the case of a much prolonged contact (24h corresponding 144 times the theoretic time of contact), it is noticed that, if this immediate effect is not more pronounced, on the other hand it is noticeable for a much longer acetylcholinesterasic activity extends beyond forty days. In the same conditions, three successive weekly treatments lead the acetylcholinesterasic activity to the level of vital activity.

Acetylcholinesterase↗
PubMed1981

[The problem of the use of mercurials cosmetics in Senegal (author's transl)].

The use of skin-lightening preparations appears to be a problem for the coloured women in Africa as well as for the Black People in general. The mercurial creams occupy a place of choice into the most useful products for the skin depigmentation. An epidemiological study from twenty senegalese women using mercurials cosmetics has permitted to determine a mean value of 155,75 +/- 75,38 ppm Hg in scalp hair while the normal level is less than 10 ppm. An experimental study was realised with monkeys (Papio papio) treated with a soap containing mercuric biiodide. This study has shown, after only three months of experimentation, a significative augmentation of mercury levels in all the organs and specially in the kidneys and the hair.

Adult↗
PubMed1981

[Mercury and methylmercury pollution of fishery products. Toxicological effects on human health (author's transl)].

Since the japanese mass poisoning in 1954's, classically named today "Minamata disease", mercury and its derivatives occupy a place of choice into the most worrying chemical pollutants for the human health and a lot of studies about the pathways by which mercury enters in its biogeochemical cycle or the environmental mercury levels are resumed in this paper. The most important aspects of mercury ecotoxicology are reviewed here: biological methylation reaction, bioaccumulation and biomagnification of these toxics in te aquatic ecosystems. The authors also describe the mercury and methylmercury metabolism and the symptomatology of the methylmercurial poisoning; with emphasis that infraclinic chronical manifestations, or large epidemiological interest, are not well known. It should be necessary to found a sensitive biochemical test, specific of this intoxication. The studies about the initial body burden assessment or the threshold values of mercury in easily obtainable specimens (blood hair) are only available for a statistical distribution. At individual levels, a number of factors occur, particularly the presence of selenium who should act as a biological antagonist of methylmercury.

Animals↗
PubMed1980

[Experimental study of the bioaccumulation of inorganic mercury and methylmercury in the goldfish (Carassius auratus L.)].

The study of the mercury and methylmercury bioaccumulation by various species of fish is only possible experimentally when the animals are maintained fasting during a few days. With a such experimentation in the goldfish (Carassius auratus L.), the authors are showing that methylmercury is much more accumulated than inorganic mercury: the transfert factor is about 760 to 780 for the methylmercury chloride and only 90 for the mercuric chloride. In fact a lot of variables occur in this phenomena of bioaccumulation (experimentation time, size and age of fish, solvant space, concentration of oxygen and mercury in water,...) and make this study difficult.

Animals↗
PubMed1979

[Residue analysis of methiocarb, repellent for the Quelea, in crops var. sorghum sp. (author's transl)].

The methiocarb (4-methylthio 3,5-dimethylphenyl N-methylcarbamate) has repellent properties towards against Quelea, a small bird deteriorating crops in Africa. The residue analysis of the carbamate compound and of its possible metabolites on treated Sorghum sp. was completed by TLC after chloroformic quantitative extraction. The isolation of metabolites by two dimensional thin layer chromatography demonstrates the presence of methiocarb sulfone. The quantitative survey of residues was achieved by the treatment of the methiocarb by hydrolyzed derivatives by dansylchloride, a very fluorescent component. The fluorescent densitometry of dansylated by methylamine allows a total measurement of the residues at a level of less than 10 ng. This investigation reveals the disappearance curve of methiocarb in our samples in process of time and to define the half-live and, therefore, the intervals of treatment. Taking into account the RI 50 index, our results provide encouraging support for the utilization of methiocarb in the eradication of the harmful Quelea.

Animals↗