Predicting of postoperative cardiac events using ambulatory ECG monitoring prior to abdominal aortic surgery.

Objectives: The purpose of this study was to estimate the value of preoperative electrocardiographic (ECG) monitoring in predicting postoperative cardiac events in patients undergoing abdominal aortic surgery.

Design: A prospective open study.

Setting: University Hospital.

Testosterone elevates pituitary prolactin content of long-term castrated rats under constant but not under periodic light.

Intact and castrated male rats were kept for 1 week under constant or periodic light, during which time they received daily injections of either vehicle or testosterone propionate (125 or 250 micrograms day-1). Immediately after the experiment the rats were decapitated and serum and pituitary prolactin were measured radioimmunologically. The pituitary prolactin content was decreased after castration in both lighting conditions.

Initially high plasma prolactin levels are depressed by prolonged psychological stress in males.

Plasma levels of prolactin were determined by radioimmunoassay in medical students before and after an academic examination and corresponding control periods. Before the academic examination, both the males' and the females' prolactin values were higher than their control values; they were statistically significant, however, only in the males. After the examination, the prolactin values were lower than the control values in the males, but not in the females.

Endocrine patterns before and after examination stress in males and females.

Plasma levels of cortisol, adrenocorticotropin (ACTH), and growth hormone (GH), were determined by radioimmunoassay in medical students just before (Exp.1) plasma values of cortisol were higher than their control values in both sexes, statistically significantly, however, only in males. The difference of cortisol behavior between the sexes was not significant.

Rapid eye movement sleep deprivation depresses plasma FSH and LH in castrated rats.

In castrated Wistar rats four days of Rapid Eye Movement sleep (REMs) deprivation by the cuff pedestal method induced decrements in plasma LH and FSH. The adenohypophyseal levels of these hormones were decreased in the REMs-deprived rats and in the control rats kept on pedestals with the supporting cuff in the elevated position as compared with the home-cage control rats. The results are discussed in terms of regional brain metabolic activity and transmission.

REM sleep deprivation increases early morning pineal melatonin in castrated rats.

Recently nighttime melatonin levels have been shown to be attenuated in depressive patients or patients with dementia of the Alzheimer type. On the other hand, depression can be transiently relieved by deprivation of rapid eye movement sleep. Since exogenous melatonin administration increases rapid eye movement sleep and slow wave sleep in the rat, could rapid eye movement sleep deprivation then inversely influence endogenous melatonin production? We found indices that in castrated Wistar rats 4 days of rapid eye movement sleep deprivation by the cuff pedestal method elevates the pineal content of melatonin by a factor of two at 1 to 2 h after light onset.

Effect of neonatal androgenization on the testosterone feedback sensitivity in adult rats in two lighting conditions.

Neonatally androgenized and intact adult male Wistar rats received daily, during 1 week, either testosterone propionate or sesame oil injections in periodic or constant light. Serum and pituitary gonadotropins and hypothalamic LHRH were measured. In periodic light, neonatal androgenization did not change the serum concentration or pituitary contents of gonadotropins, or the hypothalamic content of LHRH.

Lighting conditions affect testosterone feedback sensitivity in castrated rats.

It has been shown in the Syrian hamster that a short photoperiod sensitizes the hypothalamo-hypophyseal axis of castrated animals to the negative feedback effect of testosterone. There is some evidence that even the reproductive system of the rat, which is generally considered not to be very sensitive to light, can respond to changes in illumination. Therefore, we found it of interest to examine whether alterations in lighting conditions produce changes of sensitivity in the negative feedback effect of testosterone in the rat.

Twenty-four-hour patterns of pineal melatonin and pituitary and plasma prolactin in male rats under 'natural' and artificial lighting conditions.

Natural lighting differs from usual artificial lighting mainly as follows: it has larger spectral composition, fluctuations of intensity during the day, higher intensity levels during the night (moonlight, starlight), and gradual changes of illuminance at dawn and dusk. The present experiment was performed in order to study whether these features of lighting affect the 24-hour patterns of melatonin and prolactin in male rats. The rats were kept 7 days in 'natural' lighting (sunlight through windows) or in artificial lighting (cool white fluorescent lamps) of similar periodicities (13/11 h light/dark).

Examination stress decreases plasma level of luteinizing hormone in male students.

Plasma levels of luteinizing hormone (LH) and testosterone were determined by radioimmunoassay in medical students just before (Exp. 1) and after (Exp. 2) an academic examination and corresponding control periods.

Examination stress affects plasma levels of TSH and thyroid hormones differently in females and males.

Plasma levels of TSH and thyroid hormones in 22 male and 27 female medical students were determined by radioimmunoassay before and after an academic examination. The plasma values of TSH were slightly higher in both sexes on the examination day than on the control days. The values were lower after the examination than before it in females but not in males.

Rapid eye movement sleep deprivation affects sleep similarly in castrated and noncastrated rats.

Twenty-four-hour recordings of electrophysiological correlates of the sleep-waking cycle in castrated and noncastrated Wistar rats were performed to validate the cuff pedestal technique in the deprivation of rapid eye movement sleep. An undisturbed pattern of sleep was found in both castrated and noncastrated rats when the cuffs were in the raised position. The lowering of the cuff for 4 days virtually abolished REMs in both groups of rats.

Spectral properties of light affect plasma and pituitary gonadotropins in male rats.

In order to find out whether different light spectra have any role in regulating the gonadotropin levels in male rats, we compared the 24-hour patterns of plasma and pituitary gonadotropins in rats kept for 7 days in natural or in cool white artificial lighting (exp. I). The intensity and periodicity of the two lighting conditions were adjusted as similar as possible.

Increased aggression after rapid eye movement sleep deprivation in Wistar rats is not influenced by reduction of dimensions of enclosure.

Twelve female and twelve male Wistar rats were assigned to home groups, platform-control groups, and rapid eye movement sleep deprivation groups. The deprivation was performed with the cuff-pedestal method. Rats were tested in pairs in a shrinking chamber to increase proximity of the rats and to provoke interaction between them.

Effects of rapid eye movement sleep deprivation on regional brain metabolism as measured by 2-[14C]deoxyglucose autoradiography.

Regional brain metabolic activity of six male Sprague-Dawley rats was investigated with 2-[14C]deoxyglucose autoradiography. Regional brain metabolic activity was determined bilaterally for 60 brain structures, using laser densitometry. After 5 days of uninterrupted rapid eye movement sleep deprivation, increased metabolic activity was found in the lateral habenula, the caudal and middle parts of the limbic system, and in the corpus callosum.

Little oscillation of daily food intake in mousekiller rats as opposed to nonkiller rats before any confrontation with mice.

During 46 consecutive days the daily food intake and weight were recorded in 16 male Wistar rats. On Days 31-45 one mouse was presented each rat daily. Before any experience with mice (Days 0-27) the mousekiller rats, compared with the nonkiller rats, regulated their individual food intake more closely to their homeostatic equilibria, corrected for the linear trend.

Food consumption and mouse-killing in Sprague-Dawley rats.

The effects of daily 10-min mouse exposure tests on food consumption were studied in killer and non-killer Sprague-Dawley rats. The results showed both mouse-killers and non-killers significantly to decrease their food consumption when tested daily for mouse-killing. The effect was more pronounced in mouse-killers than in non-killers and the day-to-day individual fluctuation of food consumption was greater in mouse-killers during the mouse confrontation period.

The effect of blood sampling on plasma levels of LH and FSH in male rats.

Plasma levels of LH and FSH in male rats were compared in blood samples collected by decapitation or through permanently implanted aortic cannulae. The hormone levels were higher in the samples taken by decapitation. After cannulation, the gonadotropin levels remained unchanged when sampling occurred only once a day and each rat was bled 1-3 times over a period of 7 days (sample volume 2.

The effect of lighting conditions on plasma levels of gonadotropins in castrated male rats.

Plasma levels of LH and FSH were measured in castrated male rats kept in a 12/12 h light/dark cycle (control lighting), continuous light or continuous darkness. In Experiment I, the animals were kept in the three illumination conditions for 5 weeks. They were then decapitated for blood collection.

Validation of the cuff pedestal technique for rapid eye movement sleep (REMs) deprivation by electrophysiological recordings.

Twenty-four-hour recordings of electrophysiological correlates of the sleep-waking cycle in the rat were performed during different stages of cuff pedestal treatment. It was found that rats adapted to live on pedestals with the cuff raised displayed undisturbed patterns of sleep and wakefulness. Lowering the cuff for three days resulted in virtually total disappearance of rapid eye movement sleep (REMs), while slow wave sleep (SWs) was only slightly reduced.

Mouse-killing in Sprague-Dawley rats: effects of lighting conditions.

Sixteen male Sprague-Dawley rats were studied in artificial daylight and in red light for mouse-killing. Fifty percent of the rats killed mice. Killing varied, however, considerably: only seldom did it occur on consecutive days.