Life events and the course of bipolar disorder.

The authors examined the impact of life stress on the course of bipolar disorder over a 2-year period in a group of 61 outpatients. The patients were followed prospectively with ongoing assessments of stressful life events, symptoms, levels of maintenance medication, and compliance with treatment regimens. As predicted, survival analyses indicated a significant association between life events and relapse or recurrence of the disorder. These effects could not be explained by differences in levels of medication or compliance. Further research is recommended to examine which specific subgroups of bipolar patients are most susceptible to stress.

Psychiatric history and stress: predictors of severity of unipolar depression.

Unipolar depression is frequently a recurrent or chronic disorder. In studies on predicting its course, outcomes are typically linked to either psychiatric features or stressful life events. In order to integrate the 2 approaches, 51 unipolar patients were assessed periodically over at least 1 year for symptoms, stressful events, and chronic stressors. It was hypothesized that adverse family history and early age of onset impair role functioning and coping capabilities, thereby contributing to stressful circumstances that predict severity of depressive reactions. Results of causal modeling analyses supported a model in which background factors were associated with severity of depressive outcomes as mediated by their effects on stress variables. Such a model implicates the self-perpetuating nature of clinical depression, both for the individual and across generations.

Sociotropy/autonomy and vulnerability to specific life events in patients with unipolar depression and bipolar disorders.

Followed samples of unipolar and bipolar patients for a 6-month period, with independent assessment of symptoms and life events. Patients were initially categorized into subtypes using Beck's Sociotropy/Autonomy Scale, with the prediction that onset or exacerbation of symptoms, as well as more total symptoms, would occur for sociotropic individuals experiencing more negative interpersonal events than achievement events, and for autonomous-achievement patients experiencing more achievement events than interpersonal events. Results were confirmed for unipolars, indicating that the course of disorder was associated with the occurrence of personally meaningful life events, but not for bipolars. Further research is recommended to examine whether the effect is equally robust for both subtypes of unipolars, whether longer study duration may be required for bipolars, and whether a cognitive self-schema mechanism may account for the specific vulnerability to a subset of stressful events.

Measurements of visual suppression during opening, closing and blinking of the eyes.

We have previously shown that the sensitivity of human vision, as measured with a stimulus that bypasses the eyelids, is briefly impaired at the time of an eyeblink. We now find that the visual loss is almost equally extensive during eye closure if the eyes then remained closed. But little impairment occurs during eye opening when the eyes then remain open. We have previously concluded that, in blinking, visual suppression is associated with an inhibitory signal sent out by the brain. We now conclude that this signal arises primarily as a corollary to the efferent discharge that closes the eyelids.

Perception of suprathreshold stimuli during saccadic eye movements.

We have investigated the extent to which a graded series of suprathreshold stimuli are perceptually weakened by saccadic suppression. Stimuli were brief decrements of variable amplitude in the illumination of a Ganzfeld. For each of several decrements presented during fixation, we determined a matching amplitude of decrement presented during saccades. The measure of saccadic suppression was the ratio of these two amplitudes. The matches made by three observers exhibit ratios as high as 6:1 (0.8 log unit of suppression) near the threshold. Suppression decreases systematically as the strength of the stimulus increases, reaching 0.1 log unit or less for stimuli 2 log units above threshold.

The timing of psychosocial transitions and changes in women's lives: an examination of women aged 45 to 60.

Sixty-four middle-class women from four cohorts aged 45, 50, 55, and 60 participated in a retrospective interview concerning psychosocial changes in their adult lives. Their responses provided self-report data relating to specific psychosocial changes, and judges who read the interview protocols provided independent ratings of major psychosocial transitions. The results indicated that major psychosocial transitions were more likely to be associated with phases of the family cycle than with chronological age; within the family cycle, transitions were more likely to occur during the preschool (28% of the women), launching (42% of the women), and postparental (33% of the women) phases than during the no children, school-age, or adolescent phases; transitions associated with the preschool and launching phases were characterized by dissatisfaction, personal disruption, marital unhappiness, and decreased personal development, whereas transitions associated with the postparental phase were characterized by personal mellowing and improved marital relations; and finally, numerous self-reported psychosocial changes were associated with family cycle phase, and a small number of changes was associated with chronological age.

Effect of low levels of exogenous progesterone on puberty in beef heifers.

Twenty eight prepuberal Charolais-Angus cross heifers approximately 15 months old and averaging 334 kg were implanted intravaginally with either a placebo (control, 9 heifers) or progesterone containing implant (treated, 19 heifers). Implants were left in place 3 days. Seventeen heifers (8 controls and 9 treated) retained implants. Plasma progesterone concentrations were < .4 ng/ml in control heifers and 1.5 +/- .59 ng/ml in treated heifers while implants were in place. Seven heifers, all in the treated group, were observed in estrus within 4 days after implant removal. All but one heifer observed in estrus had elevated plasma progesterone concentrations 12 days after implant removal. None of the heifers not observed in estrus had elevated progesterone levels at this time. This study indicates that low levels of exogenous progesterone (1 to 2 ng/ml plasma for 3 days) will induce estrus in prepuberal heifers following its withdrawal.

Suckling induced cortisol secretion in young beef cows.

The profiles of plasma cortisol concentration in response to suckling were determined in 10 young, postpartum beef cows between days 25 and 85 postpartum. Two trials, comprised of five cows each, were conducted in the fall (I) and spring (II), respectively. In both trials, plasma cortisol rose within 10 minutes after suckling began and was significantly higher than pre-suckling concentrations (P<.01). Over the next 30 minutes in trial I and 40 minutes in trial II, the cortisol level progressively fell back to the pre-suckling levels. This profile was qualitatively similar among the days postpartum on which the cows were bled. Neither the profile nor the peak concentration after suckling changed significantly (P>.10) as days postpartum lapsed. Finally, there was a significant difference (P<.01) in mean plasma cortisol between the cows in trial I compared to the cows in trial II.

Prolactin and luteinizing hormone (LH) release throughout the postpartum period in the suckled first-calf beef cow.

A study was performed to examine the release patterns of prolactin and LH of young beef cows with one (single calf) or two calves (double calf) throughout the postpartum interval. The effect on prolactin release of intramuscular and intra-carotid administration of lergotrile and intra-carotid administration of L-dopa was also examined. In approximately 50% and 65% of the cases, no prolactin release could be detected after the beginning of or during the suckling stimulus in cows with one or two calves respectively. LH plasma concentrations remained constant throughout the experiment in all animals. The chosen intramuscular lergotrile treatment lowered plasma prolactin concentrations to baseline levels but had no effect on the length of the postpartum interval. No effect on prolactin release was observed by the given intra-carotid treatments of both lergotrile and L-dopa. First postpartum estrus was observed on days 67 and 88 in the single and double calf cows respectively. The number of suckling periods did not change during the postpartum period but their duration decreased during the same period. These results demonstrate that in at least half of the cases the suckling stimulus does not cause a release of prolactin from the pituitary in the young beef cow. Also, the inhibitory effect of suckling on the resumption of ovarian cyclic function postpartum appears to be of a quantitative nature and mediated by a factor other than prolactin.

An intra-abdominal chamber for continuous long-term observation of the sheep ovary.

Rupture of the ovarian follicle (ovulation) is a clinically important event in reproduction, and its prediction or detection has been the object of many investigations. Direct observation is presently the only conclusive concurrent evidence of ovulation and is, therefore, necessary in investigations on the validity and precision of signals hypothesized to be time-related to ovulation. For this purpose, an ovary observation chamber, with a kink-resistant polyvinyl chloride viewing conduit, has been fabricated from resin-reinforced fibreglass, further coated with a silicone elastomer. The chamber is implanted surgically in ewes with the ovaries placed in the distal section of the chamber. The rigid fibreglass construction can withstand the normal physical activity of the animal, while the flexible portion of the chamber allows movement of the flank musculature with minimum impairment of blood supply at the ovary pedicle. A glass window permits continuous external observation and photography of both ovaries with their follicles. Both ovaries of each of 8 sheep were mounted in a chamber and, after an initial swelling, presented relatively normal morphology for 2-9 weeks. The tissue in contact with the chamber showed no adverse reaction. No infection was observed as long as the tissue-biomaterial interface near the abdominal skin was intact. In 6 of the 8 sheep implanted with the device, components of normal cyclic development have been identified by histological, photographic, or hormonal evidence.

Periovulatory changes in ovarian temperature in ewes.

Thermistors were implanted in intact ewes, and ovarian and aorta temperatures were recorded for 72 hours, following the removal of a progesterone implant intended to induce estrus. Serum levels of luteinizing hormone (LH) were measured hourly over a 10 hour period beginning at the onset of estrus. Ovaries were examined by laparotomy at the end of each experiment. Estrus behavior, LH surge, and a fresh corpus luteum were all found to be present in four, and absent in two, of a total of six experiments. To remove variations in basal body temperature, ovarian temperatures were measured relative to aorta temperature at all times. In the nonovulating ewes, both mean ovarian temperatures varied at random, whereas in the ovulating ewes they decreased by approximately 0.15 degrees C. to reach a minimum 1 hour before the time of maximum rate of increase in LH. The ovulating ovaries differed from the contralateral ovaries (where ovulation did not occur) in two respects: the mean temperature in the ovulating ovaries was lower by 0.02 to 0.10 degrees C. at all times, and its preovulatory decrease began several hours earlier. When taken in conjunction with published data on secretion and on the local and systemic effect of estradiol, these findings, are consistent with the hypothesis that ovarian estradiol induces an increase in ovarian blood flow. A heat-sink effect of the uterine mass due to its proximity to the ovaries may also be involved.

Effect of pentobarbital anaesthesia on luteinizing hormone levels in intact and ovariectomized ewes.

In six intact ewes, deep anaesthesia lasting 1-2 h was induced with pentobarbital given intravenously at the onset of oestrus. In a second group of six ovariectomized ewes, light pentobarbital anaesthesia was induced following a control period of 4 h and then maintained for 2, 3, or 4 h. No drug was given to control animals (seven in the first group, three in the second). Serum levels of luteinizing hormone (LH) were determined by radioimmunoassay hourly in the first group, and at intervals of 5 or 10 min in the second. In the oestrous ewes, pentobarbital did not prevent or modify the expected LH surge. In the ovariectomized ewes, the drug, while not affecting the pulsatile release pattern of LH, reduced average LH levels to about half their control values (P smaller than 0.001) when given in a dosage maintaining 3 or 4 of light sleep; the 2-h dosage had no such effect. These differential effects of pentobarbital indicate that LH secretion in ewes is regulated by more than one mechanism. In particular, our findings are consistent with a hypothesis that there are, in ovariectomized ewes, independent central regulatory mechanisms for the amount of LH released, and for the time pattern of its release.