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Biomedical subjects

J Y Daniel

Publications and source records attributed to J Y Daniel.

53 records · Page 3Linked to original sources
PubMed1980

[Binding capacity of the testosterone-binding plasma protein in 2 wild mammals with cyclic testicular activity, the fox and badger].

The binding capacity of the plasma testosterone binding globulin (TeBG) as determined by the equilibrium dialysis method, in fox and badger, was shown to wary in relation to the seasonal endocrine activity of the testis. During the winter breeding period, the TeBG binding capacity was low in the fox and high in the badger, whereas an opposite situation prevailed during the sexual quiescence phase. Independent of those seasonal variations, the binding capacity of TeBG was always lower in fox than in badger.

Animals↗
PubMed1980

[Effect of the equilibrium constant of steroid-transcortin binding on the metabolic clearance rate of cortisol and corticosterone in the rabbit].

In the Rabbit the metabolic clearance rate (MCR) was shown to be eightfold greater for corticosterone than for cortisol. This marked difference in the clearance kinetics of both glucocorticosteroids appears to result from a difference in the affinity of transcortin (CBG) towards both hormones, since the maximal association constant of CBG was twice as high for cortisol as for corticosterone.

Aldosterone↗
PubMed1978

The effect of lesions of the epithalamus on plasma aldosterone and corticosterone levels in Japanese quail.

The peripheral plasma aldosterone and corticosterone concentrations were measured by CPBA and RIA method in Japanese quails in which the subcommissural organ (SCO) or the habenula had been destroyed. Lesion of the SCO reduced the plasma aldosterone level by 50%. The lesion of n. habenularis medialis and lateralis on the other hand did not affect the plasma corticosteroid level. It is suggested that in birds the SCO takes part in a multifactorial regulation of aldosterone secretion.

Aldosterone↗
PubMed1977

Evidence of androgen and estrogen receptors in the preen gland of male ducks.

Androgen receptors have been found in duck preen glands by using dextran-coated charcoal adsorption. They bound DHT with high affinity (KD = 0.2 nM), limited capacity (45 fmoles/mgP) and good specificity. They sedimented at 8 S in a sucrose gradient and were destroyed by pronase digestion and heating. An estrogen receptor having different binding specificity was also demonstrated. On the basis of a marked annual cycle of gonadal activity in ducks, this system appears appropriate for studying the regulation of sex steroid hormone receptors.

Adsorption↗
PubMed1975

Experimental studies on the annual cycles of thyroid and adrenocortical functions in relation to the reproductive cycle of drakes.

The annual variations in the basal plasma contents of testosterone, thyroxine and corticosterone have been measured in Peking drakes living outdoors, in Southern France. 10 The plasma testosterone titer underwent a more than 20-fold increase during the vernal reproductive period (March-April). In early June the circulating testosterone fell to near autumnal values, and the testosterone MCR was augmented. These were the first manifestations of the cessation of the vernal reproductive period. 20 The plasma thyroxine levels were minimal in autumn, moderately augmented (40%) in winter (January-March), but exhibited a 3-fold increase in early June. The resulting steep (13-fold) increase of the plasma thyroxine/testosterone ratio preceded the onset of the post-nuptial moult. 30 Modifications of testosterone secretion and clearance rate similar to those occurring in June were initiated in spring by i.m. injections of thyroxine at a dosage (1 mg/d) that induced June-July thyroxine plasma levels. On the other hand, an experimentally induced steep decrease of testosterone (castration) induced enhanced plasma thyroxine concentrations similar to the June values, while an induced (10 mg/d testosterone i.m.) hypertestosteronemia corresponding to the reproductive period depressed the plasma thyroxine levels. Strong reciprocal negative interactions between testis and thyroid might therefore afford a partial explanation of the peculiar thyroxine/testosterone imbalance that occurred in June immediately prior to the moult. 40 Cold-exposed "short-day" (December) ducks exhibited a marked increase in plasma thyroxine levels, while exposure of December ducks to "long days" (18L-6D) at 25 degrees C depressed the thyroxine titers. The inhibitory effect of "long days" on the blood level of thyroxine was further evident in castrated ducks. Exposure of "short day" ducks (December) to a combined treatment by "long days" (18L-6D) and cold (4 degrees C) produced an endocrine picture similar to the January-March pattern, i.e. highly increased testosterone plasma levels, but unaffected testosterone MCR, together with a moderate increase in plasma thyroxine concentration. 50 Corticosterone plasma concentrations increased during the reproductive season, as a result of a seasonally augmented binding-capacity of the CBG. Exogenous testosterone (10 mg/d) which induced spring-like circulating levels of male hormones, caused a similar increase in CBG-bound and total corticosterone levels. 60 In June the MCR of both corticosterone and aldosterone were elevated (as was the testosterone MCR). Similarly enhanced MCR of both corticosteroids were brought on in spring by an exogenous thyroxine treatment, leading to a June-like state of hyperthyroxinemia.

Adrenal Cortex↗