Correlates of dental student stress

The purpose of this study is to identify correlates of dental student stress. Associations between characteristics of dental students and their stress levels are examined, along with the association of stress with drug use and health problems. A total of 300 out of 315 dental students completed a questionnaire that measured the frequency and stressfulness of 31 stressors; drug use; health problems; and student characteristics including Type A behavior, career commitment, demographics, and lifestyle variables. Characteristics that were associated with a higher stress level were a higher level of Type A behavior and lower level of career commitment. Greater stress was also associated with a greater frequency of health problems. The results suggest an interactional stress model in which the personalities and attitudes of students are important mediators of the stress response.

Noise-induced temporary threshold shifts: the effects of anticipatory stress and coping strategies

Temporary Thresholds Shifts were assessed in five groups from before to after 5-minute exposure to 110 dB SPL white noise and in one additional group without noise exposure. In each group the baseline conditions were designed to elevate psychological stress via anticipation of the noise and venipuncture procedures. In the three experimental groups, procedures to reduce psychological stress were employed: Information, Relaxation, and Behavioral Avoidance. Manipulation checks supported the effectiveness of these arousal-reducing interventions. Temporary threshold shifts were considerably greater in two of the experimental conditions than in the noise-exposed control conditions.

Effect of two-week infusion of deamino D-arginine vasopressin in rats

Our purpose was to investigate a method of prolonged desmopressin (DDAVP) infusion in a free roaming rat to better understand the SIADH (syndrome of inappropriate antidiuretic hormone secretion) syndrome in man. DDAVP was infused for 2 weeks from implanted self-powered osmotic minipumps. At the end of that time, plasma DDAVP and urine osmolality were both significantly elevated in experimental as compared with control animals. However, hyponatremia and hypoosmolality, which are characteristic in the SIADH, did not develop. Our observations suggest that inappropriate high antidiuretic hormone levels do not necessarily lead to the SIADH either by urine sodium loss or by water retention if animals decrease water intake.

Primary hypothyroidism in chronic renal failure

Serum thyroid hormone concentrations have been measured in 8 patients with chronic renal failure (CRF) who are currently enrolled on a chronic hemodialysis program. Three of these patients were diagnosed to be suffering from coexistent primary hypothyroidism whereas the other 5 were considered euthyroid. There was a variable decline in serum thyroid hormone levels in both groups. However, the serum TSH response to TRH was normal or blunted in the euthyroid group but was characteristically brisk in subjects with CRF and coexistent primary hypothyroidism. The TRH test may be useful in the diagnosis of primary hypothyroidism coexistent with CRF.

Abnormal retinal artery responses to stress in patients with type I diabetes

The brachial artery pressure and retinal artery pressure responses to a one-minute cold pressor test were evaluated simultaneously in 14 patients with type I diabetes mellitus (six with and eight without diabetic retinopathy) and 10 age-matched control subjects. Five patients with type I diabetes had autonomic neuropathy. Mean baseline brachial artery pressure and retinal artery pressure were similar in patients with type I diabetes and control subjects. After cold pressor testing, the brachial artery pressure increased significantly (p less than 0.01) compared with baseline values in both groups. Retinal mean arterial pressures increased significantly (p less than 0.001) after cold pressor testing compared with the baseline values only in patients with type I diabetes. Positive correlation was found between the brachial and retinal mean arterial pressures after cold pressor testing (r = 0.48; p less than 0.05) in the diabetic patients but not in the control subjects (r = 0.10; p = NS). No correlation was found between the retinal artery pressure and age of onset of diabetes, duration of diabetes, the presence or absence of diabetic retinopathy, and glycemic control. Four patients with autonomic neuropathy and low retinal artery pressures, which remained unchanged after cold pressor testing, had no diabetic retinopathy. The fifth patient with autonomic neuropathy and exaggerated systolic brachial artery pressure (175 mm Hg) and retinal artery pressure (more than 80 mm Hg) responses had severe background diabetic retinopathy. In conclusion, abnormal retinal artery responses to stress are present in patients with type I diabetes. This may be modified by the presence or absence of both autonomic neuropathy and hypertension. The biologic significance of these findings is yet to be determined.

The repeatability of rearing performance of Merino and Dorset Horn ewes and its relationship with mature pelvic size

Data from one Dorset Horn and three Merino flocks were used to examine factors influencing the ability of ewes lambing four times to successfully rear their lambs. Repeatability of rearing performance, defined as the ratio of lambs weaned:lambs born, was estimated in three flocks and the intra-class correlation estimates ranged from 0.05 to 0.17, with a mean of 0.10. Ewes rearing at least one lamb at their first lambing reared an average of 7.6% more lambs at each of the subsequent three lambings, compared with those that failed to rear a lamb at their first lambing. Mean pelvic dimensions, notably the conjugate diameter and the area of the pelvic inlet, of mature ewes, which reared lambs on three or four occasions were significantly larger in two flocks than in ewes which had poorer rearing performances (P<0.05), whereas in a third flock they were not significantly different. In the two flocks in which the significant differences were observed, mature pelvic dimensions were correlated with rearing performance at individual lambings. Rearing performance in these two flocks increased, respectively, by 16.3 and 6.3% per cm increase in conjugate diameter, and by 1.4 and 0.5% per cm2 increase in pelvic area (P<0.05). The slopes of these linear regressions were significantly greater for single than for twin-born lambs (P<0.05). The relationships between rearing performance and pelvic dimensions were also significantly curvilinear, the slopes of the regressions being significantly steeper below the mean pelvic dimensions than above them (P<0.05). Removing differences between ewes in pelvic dimensions reduced the repeatability of rearing performance. Allowing for differences in conjugate diameter reduced the repeatability in two flocks from 0.15 to 0.05, and from 0.09 to 0.08, respectively. In both flocks, allowing for differences in pelvic dimensions reduced the repeatability of rearing single lambs more than that for twin lambs.

The relationship of endogenous ACTH levels to visual-attentional functioning in patients with congenital adrenal hyperplasia

The within subject experimental approach of either doubling cortisone medication dose or withdrawing steroid treatment for 36 hr preceding behavioral testing was found to induce corresponding significantly elevated or suppressed plasma ACTH levels, as measured by radioimmunoassay, in six of eight adults diagnosed as having congenital adrenal hyperplasia (CAH). During the session characterized by elevated ACTH levels, the CAH patients exhibited significantly reduced median reaction times on the Sternberg Item Recognition Task. Their response pattern was suggestive of facilitated visual attentional functioning and/or overt motor response capacity rather than alteration of simple cognitive processing. Moreover, Sternberg performance was significantly correlated with endogenous ACTH levels but not with levels of plasma cortisol or cortisone replacement medication. This enhancement of performance paralleled a previous finding of improved performance on the Sternberg paradigm by normal adults following exogenous administration of ACTH 4-10 (Ward et al., 1979). Further analysis of the Sternberg performance suggests that other variables such as mineralocorticoid treatment, type of CAH impairment, and sex may act to moderate the degree of ACTH-related facilitation on this task. Performance on other visual and verbal attention and memory tasks, found earlier to be sensitive indices of exogenous administration of ACTH 4-10 and related fragments, was not significantly altered by manipulation of endogenous ACTH levels in these CAH patients.

Angiotensin II and norepinephrine antagonize the secretory effect of VIP in rat ileum and colon

Vasoactive intestinal polypeptide (VIP) induces intestinal secretion of water and electrolytes in experimental animals and man. We assessed the ability of angiotensin II (AII) and norepinephrine (NE) to block the secretion evoked by VIP, in vivo. Ileal and colonic segments in rats were perfused in situ for two hours with a physiological buffer containing [14C]-PEG-4000 as a volume marker. Saline (0.9% NaCl) was infused intravenously during the first hour and VIP or a combination of VIP plus AII or NE was infused during the second hour. All (0.7 ng/kg/min) alone enhanced water absorption significantly (p less than 0.01) in the ileum and an appreciable, although not a statistically significant, effect was observed in the colon. AII antagonized the secretory effects of VIP in the ileum as well as in the colon. Norepinephrine (5 micrograms/kg/min) also reversed the effect of VIP on the small intestine and colon. Although the mechanism by which AII antagonizes the secretory effects of VIP has not been identified, it is probable that AII promotes absorption, at least in part secondary to release of mucosal NE.

Specific binding sites for vasoactive intestinal polypeptide on nonadherent peripheral blood lymphocytes

Vasoactive intestinal polypeptide (VIP), an octacosapeptide isolated from porcine duodenum and thought to have neuromodulator function in several functional systems (gastrointestinal tract, brain, lung, genital tract, heart), was recently detected in human neutrophils by radioimmunoassay. Subsequent studies demonstrated a VIP-mediated increase in lymphocyte adenylate cyclase. In this paper, VIP binding studies are presented using viable nonadherent human lymphocytes. Binding of 125I-VIP to nylon wool column-purified lymphocytes is specific, time dependent, rapid, and reversible. Bound radioactivity varies linearly with the number of cells used and is displaceable by non-iodinated VIP in a dose-dependent manner with complete displacement between 1 pM and 50 nM. Scatchard analysis of competition experiments demonstrates one class of specific binding sites with a KD of 0.47 +/- 0.23 nM and a Bmax of 24.9 +/- 7.0 pM. This Bmax represents 1700 binding sites/cell. secretin, gastric inhibitory polypeptide, and glucagon did not effectively compete with 125I-VIP for binding sites. This is the first demonstration of VIP receptors in a purified population of human lymphocytes; the data suggest that VIP may modulate lymphocyte function.

Specific binding sites for vasoactive intestinal polypeptide on nonadherent peripheral blood lymphocytes

Vasoactive intestinal polypeptide (VIP), an octacosapeptide isolated from porcine duodenum and thought to have neuromodulator function in several functional systems (gastrointestinal tract, brain, lung, genital tract, heart), was recently detected in human neutrophils by radioimmunoassay. Subsequent studies demonstrated a VIP-mediated increase in lymphocyte adenylate cyclase. In this paper, VIP binding studies are presented using viable nonadherent human lymphocytes. Binding of 125I-VIP to nylon wool column-purified lymphocytes is specific, time dependent, rapid, and reversible. Bound radioactivity varies linearly with the number of cells used and is displaceable by non-iodinated VIP in a dose-dependent manner with complete displacement between 1 pM and 50 nM. Scatchard analysis of competition experiments demonstrates one class of specific binding sites with a KD of 0.47 +/- 0.23 nM and a Bmax of 24.9 +/- 7.0 pM. This Bmax represents 1700 binding sites/cell. secretin, gastric inhibitory polypeptide, and glucagon did not effectively compete with 125I-VIP for binding sites. This is the first demonstration of VIP receptors in a purified population of human lymphocytes; the data suggest that VIP may modulate lymphocyte function.

Evaluation of an intraruminal device to provide an iodine supplement for sheep

Commercially manufactured intraruminal devices providing iodine supplementation for grazing sheep were tested for three years in a flock of 200 ewes, and iodine release rates and accumulation in tissues were measured in a small flock of first cross ewes and wethers. Retention of the device exceeded 99.5%. The rate of iodine release increased from about 500 �g/d during the first few months to about 1100 �g/d resulting in an effective life of almost three years. The ewes were not iodine deficient, and supplementation by this device did not improve reproductive performance. Thyroxine levels in plasma, and iodine concentrations in tissue, were not elevated to levels which might be considered toxic, confirming the safety of the device.

Nocturnal biofeedback for nocturnal bruxism

Reports have appeared recently describing the successful reduction of nocturnal bruxism through nocturnal biofeedback. These claims of effective treatments rest mainly on the use of a single index of integrated masseter EMG levels as a measure of bruxism and are based only on short-term effects. The present study was conducted to provide a more rigorous evaluation of the effectiveness of nocturnal biofeedback for nocturnal bruxism through the use of all-night polysomnographic recordings. The results from multiple indices of bruxism are internally consistent and indicate that simple nocturnal biofeedback does not appear to be effective in reducing nocturnal bruxing. Recommendations are made for a more comprehensive approach to the treatment of nocturnal bruxism.

The effects of psychological factors on recovery from surgery

This paper has reviewed correlational studies from both inpatient hospital settings and outpatient oral surgery that demonstrate that several psychological factors are related to postsurgical recovery. Examination of these factors indicates that dentists might improve patients' recovery by giving the surgery a more positive meaning (making the outcome seem desirable), improving patients' acceptance of their condition, making patients' expectations more positive and, reducing anxiety about recovery. Other psychological factors may be helpful in identifying patients who need more support, for example, those with higher trait anxiety, vigilant coping behavior, or an internal locus of control. The review of intervention studies indicates that the best preparation techniques include giving positive suggestions and teaching coping techniques. The value of giving increased amounts of information has not been demonstrated. Also, the literature is not conclusive on varying the type of preparation to fit the personality traits of patients.

Gastrin Responses to a test meal in patients with familial medullary thyroid carcinoma

The serum gastrin response to a standard test meal was evaluated in patients with familial medullary thyroid carcinoma (MTC) and in normal subjects. Patients with MTC and elevated plasma calcitonin levels had a lower gastrin response to the test meal than did normal persons or MTC patients who had normal calcitonin levels postthyroidectomy. There was no significant difference between the mean gastrin response of the normal group and that of the MTC patients with normal calcitonin levels. The serum gastrin response was studied before and after thyroidectomy in four patients. In all four, the post-operative response was greater than the preoperative one . We conclude that patients with MTC may have reduced gastrin responses to a test meal. This effect may be related to circulating calcitonin, somatostatin, or other factors related to familial MTC.

First night effects in good sleepers and sleep-maintenance insomniacs when recorded at home

Home sleep recordings were conducted over four consecutive nights with 12 good sleepers and 12 sleep-maintenance insomniacs. Good sleepers showed decreased sleep efficiency and increased min awake after sleep onset on night 1. Insomniacs showed extended latency to onset of the first REM period and decreased REM in the first third of the initial recording night. Good sleepers and insomniacs reported no significant differences in adequacy of sleep between the first and subsequent sleep nights.

Vasopressin and oxytocin content of human fetal brain at different stages of gestation

Pituitaries from 38 human fetuses and 5 microdissected hypothalamic areas from each of 14 fetuses were assayed for vasopressin and oxytocin. The fetuses were between 15 and 34 weeks of gestation. Vasopressin and oxytocin were found in all the pituitary glands and all the hypothalamic areas studied. A trend of increasing content of both hormones was found in the pituitary gland towards the end of gestation with a marked increase in vasopressin/oxytocin ratio. The human fetus synthesizes oxytocin and vasopressin at least from 15 weeks of gestation and the presence of both hormones in the hypothalamus is not limited to the supraoptic and paraventricular nuclei.

The effects of psychological factors and physical trauma on recovery from oral surgery

This study evaluated the effects of several psychological factors on postsurgical recovery while controlling for and also evaluating the effects of the physical trauma induced by the surgery. Subjects were 38 patients (18 males and 20 females) who were scheduled to have four third molars surgically removed. The psychological factors measured included anxiety and expectations about recovery, trait anxiety, coping behaviors, and health locus of control. Surgical trauma was rated after surgery, and the following aspects of recovery were monitored: postoperative pain, interference with normal function, swelling, and healing. Poorer postoperative recovery was significantly predicted by each of the psychological variables and by higher levels of surgical trauma. In addition, the effects of the psychological variables on recovery were shown to be largely independent of the trauma effects. The data suggest that (a) future studies which give patients more positive expectations and reduce their anxiety about recovery may improve their recovery and (b) the types of patients most in need of preoperative psychological support would be those who have higher trait anxiety, vigilant coping behaviors, or an internal locus of control.

Oxytocin in microdissected hypothalamic nuclei. Significant differences between prepubertal and sexually mature female rats

We measured the concentration of oxytocin and vasopressin in microdissected areas of the hypothalamus and posterior pituitary in weanling and adult female rats. Oxytocin concentration was significantly less in adult rats as compared to weanling rats in the supraoptic nucleus, median eminence, and retrochiasmatic area with no significant differences in vasopressin content. This may indicate differences in hypothalamic-neurohypophyseal pathways in adult and weanling rats. There was a significantly greater concentration of oxytocin in the adult rat in the paraventricular nucleus, suprachiasmatic nucleus, anterior hypothalamic nucleus, and posterior pituitary, again with no significant difference in vasopressin concentration. Our results are consistent with a role for sexual maturation in increasing synthesis of oxytocin in specific hypothalamic nuclei resulting in increased storage of oxytocin in the posterior pituitary.