No abstract

No abstract

In rats with experimental hypertension the esterification of cholesterol and hydrolysis of cholesterol esters in aortae, blood serum and liver was investigated in vitro at atmospheric pressure and at raised pressure of 200 Torr, i.e. a pressure similar to that recorded in the arteries of hypertensive animals in vivo. Hydrolysis of cholesterol esters was enhanced in hypertensive animals. The increase could be detected on incubation in vivo at atmospheric pressure and at 200 Torr in serum and aortae, but in the liver only at atmospheric pressure. In hypertensive rats no decline of hydrolysis in serum and aortae, which was associated with incubation at 200 Torr in normotensive rats, was observed. Cholesterol esterification in serum in vitro was greater at 200 Torr, while in aortae it declined. In hypertensive rats esterification in serum was reduced, in aortae enhanced and in the liver the changes were not significant. The results are discussed with regard to atherogenesis in hypertension and with regard to enzyme adaptability.

The effect of intramuscular administration of glucagon (Glg) and calcitonin (Ct) on the pattern of serum calcium (Ca), in organic phosphorus (P), blood glucose (BS), immunoreactive insulin (IRI) and growth hormone (GH) was investigate in 14 patients after total thyroid ablation during replacement therapy. In seven patients the pattern of Ct after Glg administration was assessed in the same conditions. Both hormones induced a prompt and marked decrease of Ca with out any differences between effect of Glg and Ct. The decline of P due to Glg is more rapid and marked than the due to Ct, the difference being significant from 60 to 120 min. Glg caused a rapid and marked rise of BS and IRI with a tendency toward normalization up to 180 min, GH rose significantly from 120 to 180 min. The changes of BS and IRI due to Ct were slow and less marked, but prolonged: level of BS increased and that of IRI decreased. No effect of Ct administration on GH was recorded. In general, neither the effects of Glg nor those of Ct were influenced by hypothyroidism. This fact may be of importance for use of Glg in testing GH reserve in hypothyroidism. Ct after Glg administration in athyroid patients failed to exhibit any significant changes. Thus our results support the assumption about similar and independent action of Glg and Ct on calcium and phosphate homeostasis and different effects of both hormones on glucose metabolism.

Objectives Night shift work has been associated with higher breast cancer risk. It has been proposed that night shift workers experience light-induced reduction in melatonin production. Melatonin has direct oncostatic properties and a potential interplay with reproductive hormones. In this cross-sectional study the hypothesis was that night shift workers produce less melatonin and more estrogens and androgens compared to day workers. Changes in the rhythm of hormone production under different individual light exposures were evaluated. Methods 75 permanent night workers and 42 day workers of both sexes, aged 22-64 years, were recruited from 4 companies in Barcelona, Spain. Levels of 6-sulfatoxymelatonin (melatonin metabolite) and 27 steroid metabolites were measured in urine samples collected from all voids over 24-hours on a working day by all participants. Simultaneously participants wore a data logger that continuously recorded their light exposure. Sociodemographic, occupation and lifestyle information was collected for each participant by interview. Cosinor analysis was performed for 6-sulfatoxymelatonin in every individual to evaluate their circadian rhythm estimating the mesor (midpoint in the full-range), amplitude (difference of the peak value to the mesor) and peak time of production. Geometric means were calculated for each parameter in night and day workers. Results Sociodemographic and lifestyle characteristics of day and night shift groups were not significantly different. 6-sulfatoxymelatonin production was significantly lower in night compared to day workers ( mesor 10.9 vs 14.2 ng/mg creatinine respectively; amplitude 11.5 vs 18.3 ng/ml creatinine) and peak time was later in night shift workers (6:00 am vs 3:48 am). Mean oestrogen and androgen levels tended to be higher among night workers but differences were not significant. Conclusions This study indicates potential differences in melatonin and steroid profiles between night and day workers. Results from hormone levels in relation to personal light exposure using nonlinear mixed models will be presented. Objectives Nightshift work has been associated with cancer among men, but the mechanism underlying this association is not clear. We investigated whether male nightshift workers demonstrated changes in the normal circadian levels and secretion patterns of melatonin, cortisol and sex hormones that may be directly related to cancer risk. Methods Participants were 185 male nightshift workers (NSW) and 158 male dayshift workers (DSW) employed as healthcare providers, aged 22-55. Urine samples were collected throughout work and sleep periods and assayed for various hormone metabolites. Results Compared to DSW during their nighttime sleep, NSW had significantly lower levels of 6-sulfatoxymelatonin during daytime sleep, nighttime work, and nighttime sleep on their offnights (57%, 62% and 40% lower, respectively). Urinary cortisol levels in the NSW were 16% higher during daytime sleep and 13% lower during nighttime sleep on off-nights, compared to DSW...