Revue canadienne de biologie experimentale最新文献

Different concentrations of rabbit or bovine follicular fluid were added to a defined medium or to rabbit oestrous oviduct fluid containing 13 hours in utero incubated sperm. With increasing concentration of follicular fluid, the percentage of fertilization was progressively and significantly lower than in oestrous tubal secretions or Brackett's medium, alone or containing up to 5% of follicular fluid. Utilization of ova, with or without cumulus clot, to the fertilization media, had no significant effect on fertilization of rabbit eggs. Both kinds of follicular fluid used did inhibit the motility of capacitated sperm.

Adriamycin (ADR) can be linked to DNA without loss of its antitumoral activity while reducing the acute toxicity of free ADR (Deprez--DeCampeneere et al., 1979, 1980). However, the potential chronic toxic effects of both forms of ADR are poorly documented. For such a study, it is necessary to establish the sequence of treatment allowing the administration of a sufficient amount of drugs to induce chronic toxicity and a schedule leading to prolonged survival of animals. In this study, 24 Lewis rats were injected twice a week during four weeks with either free or DNA-linked ADR, and three dose levels were tested: 4, 2 and 1 mg/kg. Our results indicated that the total cumulative dose of ADR should not exceed 8 mg/kg over one month, if prolonged survival is desired. The binding of ADR to DNA seemed also to reduce the acute toxic effects induced by free ADR, in rats. However, such a beneficial effect was not observed when the chronic nephrotoxicity was considered since characteristic renal lesions were observed in all long-term survivors, whatever the dose and the form of ADR received.

The object of this study was to explore the effect of clofibrate on gastric secretion. The volume and the total acid output of Shay-treated rats (pyloric ligation) was studied after intragastric, intraduodenal, intramuscular and intraperitoneal administration of clofibrate. The experimental model was a factorial (3 X 4) random block design. The treatment factor had 3 levels: water, oil and clofibrate. The route of administration factor had 4 levels: intragastric, intraduodenal, intraperitoneal and intramuscular. The data were analyzed by analysis of variance. Compared to the control group (water and oil) the intraduodenally and intraperitoneally administered clofibrate produced a statistically significant (p less than 0.001) reduction in the volume and total acid output. The intragastric and intramuscular groups did not show a statistically significant reduction on the gastric secretion. It is concluded that clofibrate acts systemically rather than locally to reduce gastric secretion.

We propose a quantitative model which suggests that the present genetic code appeared under the influence of mutations, while optimizing its own resistance against their effects. Its evolution was realized by successive steps in which the number of translated codons grew, whereas the number of terminators decreased. The main constraint of this model is selection against nonsense mutations: the competition among many primitive codes gives advantage to those which resist best to the occurrence of nonsense mutations. The structures of the selected systems converge towards that of the present genetic code. This one appears then as built so as to resist to errors, information noise, mutations.

In anesthetized rats the retina is electrically stimulated. The evoked responses are recorded in the lateral geniculate cells with glass micro-pipettes filled with NaCl. Two patterns of discharges are elicited: non-alternating responses (NA) and alternating responses (A). The evoked responses are abolished when cobalt or aspartate is injected into the eye suggesting that the discharges are generated at the outer plexiform layer of the retina. Furthermore these data indicate that the electrical current does not activate directly the retinal ganglion cells. Glycine and G A B A had differential effects on the evoked responses. The results are compared with those obtained on rabbits.

Weights of skeletons, several viscera (heart, lungs, empty stomach and intestine, liver, spleen, kidneys) and muscles of 80 muskrats were taken. The data were analyzed and compared versus four classes of ages and sexes: adult males, adult females, sub-adult males and sub-adult females. The weight of the muscles is 47 to 50% of the live-weight in the four classes studied. The weight of the viscera is approximately 10 to 12% of the live-weight. Thus, the weight of edible matters varies, in the muskrat between 57 and 62% of the live-weight. The spleen of adult females is relatively heavier than that of adult males or sub-adult females.

Following injections of labelled amino acids around the pericruciate gyrus and the medial aspect of gyrus genualis-proreus in cat, two entirely different projection patterns are found in the head of the caudate nucleus. Massive and multiple pericruciate injections failed to label the most medial caudate nucleus which, by contrast, appears selectively labelled following genualis-proreus injections. The respective accepted connexions of pericruciate and genualis-proreus cortices with the thalamus and other subcortical structures are different. Therefore, it appears that the lateral and medial regions of the caudate nucleus must differ in their hodological and, possibly, in their functional characteristics.

The pathogenicity in Sprague-Dawley rats of Mycobacterium lepraemurium cultivated on egg-yolk medium was investigated. The results show that in vitro grown cultures provoked hugh subcutaneous lepromata in rats similar to those produced by the in vivo grown M. lepraemurium. The acid-fast bacilli isolated from lepromata of rats infected with the in vitro or in vivo grown cultures were microscopically and histopathologically identical to each other.