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Biomedical subjects

J Roffi

Publications and source records attributed to J Roffi.

At least 73 records · Page 4Linked to original sources
PubMed1966

Norepinephrine methylation in fetal rat adrenals.

The activity of phenylethanolamine-N-methyl transferase, the enzyme that methylates norepinephrine to form epinephrine, increases rapidly in the fetal rat adrenal during the day preceding epinephrine accumulation. The developmental increase in enzyme activity and the accumulation of epinephrine are prevented by fetal hypophysectomy (decapitation). Administration of adrenocorticotrophic hormone or cortisol acetate largely reverses the effect of fetal decapitation.

Adrenal Glands↗
PubMedDate not supplied

[Variations in the testicular response to HCG during the perinatal period in the rat: influence of estrogens].

The variations of the testicular responsiveness to hCG and the implication of the maternal estrogens in the functioning of the testes were studied in the perinatal male rat. Male rat fetuses treated with hCG at the end of gestation failed to show an increase in serum testosterone (T). The lack of testicular responsiveness to hCG in the fetus is neither due to anesthesia nor to a blocking effect of estrogens directly on the testes. On the other hand, hCG injected either at 4 h or at 48 h after birth increases serum T. The administration of 5 micrograms of estradiol 17 beta (E2) to the newborn male rat at the time of birth blocks the expression of the postpartum testosterone surge. The fall in the plasma estrogens and the increase of the testicular sensitivity to gonadotropic stimulation at the time of birth are factors which are very likely implicated in the determinism of the neonatal testicular hyperactivity.

Anesthesia↗
PubMedDate not supplied

The neonatal testosterone surge: a comparative study.

In the rat an abrupt discharge of testicular testosterone in the newborn male figures prominently in the development of mechanisms controlling gonadotropin secretion, sexual behavior, and also promotes the functional differentiation of the accessory sex glands. In this study we detail the temporal characteristics of this surge in the rat, and we provide comparative data documenting a similar surge-like appearance of testosterone in neonatal male mice, recently foaled male horses, and newborn human infants. Although the physiological and behavioral significance of this phenomenon for species other than the rat remains to be determined, the apparently ubiquitous appearance of the neonatal testosterone surge suggests that it may be of special significance in the sexual differentiation of many mammalian species.

Animals↗
PubMedDate not supplied

[Antigenic specificity of antiplasmodium antibodies in an endemic area: an attempt at correlation with the induction of protective immunity].

Asexual blood-stage antigens from Plasmodium falciparum related to the development of protective immunity in an endemic area were identified by statistical comparison of antigens recognized by adult immune sera with those recognized by non-immune subjects (children). After metabolic labelling of parasites in culture and immunoprecipitation, target antigens of seric antibodies were separated by polyacrylamide gel electrophoresis/SDS and detected by fluorography. Two groups of antigens were thus identified: 1) the major bands, recognized by more than 90% of the sera regardless of the patients' immune status; and 2) the minor bands, less intense on fluorograms. The corresponding antibodies were more frequent in children who had not yet acquired protective immunity than in immune adults. Thus, these minor bands do not appear essential for protection, which might instead be related to the presence of some major antigens, such as 210/196-, 136-, 121- and 80-Kd antigens. These antibodies persist for at least one year, independently of fluctuations in the rate of transmission by Anopheles.

Adult↗