Increase of nocturnal melatonin levels in hemodialyzed patients after parathyroidectomy: a pilot study.

In hemodialyzed patients hormonal disturbances are known to occur. However, melatonin levels have not been completely studied. The aim of the study was to find whether changes in calcaemia affect melatonin secretion.

Lack of melatonin response to acute administration of nifedipine and diltiazem in healthy men.

Calcium antagonists have been shown to influence some endocrinological processes in mammals. The use of calcium channel blockers in clinical practice is well documented. The current study monitored nocturnal melatonin, prolactin, and cortisol levels in 19 healthy volunteers before and after administration of calcium channel blockers.

Albumin microsphere as a drug delivery system for dexamethasone: pharmacokinetics in sheep, residue amount in cows and distribution in rats.

The aim of this study was to evaluate the potential use of albumin microspheres as a drug delivery system to provide sustained release of dexamethasone in vivo. Pharmacokinetic studies were carried out in sheep and tissue distribution in rats given dexamethasone in two injectable forms--water suspension of dexamethasone associated with albumin microspheres and water-ethanol solution of dexamethasone. When dexamethasone was associated with albumin microspheres the amount of free dexamethasone, available for absorption did not reach the high values typical of the pattern of release of dexamethasone from water-ethanol solution.

hCG stimulation test for diagnosis of androgen deficiency.

A diagnostic-stimulation test with hCG (Pregnyl, Organon) was developed for demonstration of latent testicular deficit. The test was worked out on clinically healthy men and was used to diagnose cases of anorchidism and cryptorchidism. This stimulation test may be applied in clinical andrology as a noninvasive and highly sensitive method.

In vitro effects of substance P and arginine-vasopressin on testosterone production in Leydig cells of short and long photoperiodic hamsters.

The aim of the present study was to determine the interaction between substance P (SP) and arginine-vasopressin (AVP) on basal and LH-stimulated testosterone production by Leydig cells isolated from hamsters kept under long or short days (LD-hamsters, SD-hamsters, respectively). SP inhibited the testosterone production of Leydig cells, its effect being more pronounced in the case of LH-stimulated steroidogenesis in LD-hamsters. Similarly, the addition of AVP to the culture medium resulted in a diminution of basal, as well as LH-stimulated testosterone secretions.