A pilot test of a self-guided, home-based intervention to improve condom-related sexual experiences, attitudes, and behaviors among young women.

OBJECTIVE: To conduct a pilot test of a brief, self-guided, home-based program designed to improve male condom use attitudes and behaviors among young women. PARTICIPANTS: Women aged 18-24 years from a large Midwestern University reporting having had penile-vaginal sex with two or more partners in the past 3 months. Sixty-seven enrolled; 91.0% completed the study. METHODS: A repeated measures design was used, with assessments occurring at baseline, immediately  post intervention (T2), and 30 days subsequent (T3). RESULTS: Condom use errors and problems decreased, condom-related attitudes and self-efficacy improved, and experiences of condom-protected sex were rated more positively when comparing baseline with T2 and T3 scores. Further, the proportion of condom-protected episodes more than doubled between T1 and T3 for those in the lowest quartile for condom use at baseline. CONCLUSION: This low-resource, home-based program improved condom-related attitudes and promoted the correct and consistent use of condoms.

Regulation of plasma vasopressin and renin activity in conscious hindlimb-unloaded rats.

Cardiovascular deconditioning occurs in astronauts after spaceflight or in individuals subjected to bed rest. It is characterized by an increased incidence of orthostatic intolerance. The mechanisms responsible for orthostatic intolerance are likely multifactorial and may include hypovolemia, autonomic dysfunction, and vascular and cardiac alterations. The arterial baroreflex is an important compensatory mechanism in the response to an orthostatic stress. In a previous study, we demonstrated that arterial baroreflex mediated sympathoexcitation was blunted in hindlimb-unloaded (HU) rats, a model of cardiovascular deconditioning. The arterial baroreflex also contributes to the regulation of vasoactive hormones including vasopressin and angiotensin II. In the present study, we tested the hypothesis that the neurohumoral response to hypotension is also attenuated in rats after 14 days of hindlimb unloading. To test this hypothesis, the vasodilator diazoxide (15 or 25 mg/kg) or saline (0.9%) was administered to produce hypotension or control conditions, respectively, in conscious HU and control rats. Plasma samples were collected and assayed for vasopressin and plasma renin activity (PRA). Diazoxide (25 mg/kg) produced significant increases in vasopressin and PRA compared with saline controls. HU rats exhibited significantly higher levels of vasopressin at rest and the increase in vasopressin levels during hypotension was enhanced by hindlimb unloading. Neither resting nor hypotension-induced PRA was altered by hindlimb unloading. These data suggest that although baroreflex-mediated sympathoexcitation is blunted by hindlimb unloading, hypotension-induced vasopressin release is enhanced and hypotension-induced PRA is unaffected. Increased circulating vasopressin may serve to compensate for blunted baroreflex regulation of sympathetic nervous activity produced by hindlimb unloading or may actually contribute to it.

Rats exhibit aldosterone-dependent sodium appetite during 24 h hindlimb unloading.

Hindlimb unloading (HU) is an animal model of microgravity and bed rest. In these studies, we examined the role of ingestive behaviours in regulating body fluid balance during 24 h HU. In the first experiment, all rats were given distilled water to drink while two groups were also given access to a sodium chloride solution (0.9% or 1.8%). Water and saline intakes were measured before, during and after 24 h of HU. Rats reduced water intake during 24 h HU in all conditions. During HU, rats increased their intakes of both saline solutions (0.9% NaCl (n= 11): control 7.8 +/- 3 ml; HU 18.2 +/- 4 ml; recovery 8.9 +/- 2.5 ml; 1.8% NaCl (n= 7): control 1.0 +/- 0.4 ml; HU 3.8 +/- 0.3 ml; recovery 1.2 +/- 0.5 ml). Although water intake decreased there was no reduction in total fluid intake when saline was available. Plasma volumes were reduced during HU compared to rats in a normal posture when only water was available to drink (control (n= 11) versus HU (n= 11): 4.0 +/- 0.2 versus 3.4 +/- 0.2 ml (100 g body weight)(-1)). When 0.9% saline was available in addition to water, plasma volumes after 24 h HU were not different from rats in a normal posture (control (n= 11) versus HU (n= 12): 4.3 +/- 0.4 versus 4.3 +/- 0.1 ml (100 g body weight)(-1)). Plasma aldosterone but not plasma renin activity was significantly elevated after 24 h HU. Central infusions of spironolactone blocked the increased intake of 1.8% saline that was associated with 24 h HU. Thus, HU results in an aldosterone-dependent sodium appetite and the ingestion of sodium may help maintain plasma volume.

Cardiovascular regulation of supraoptic vasopressin neurons.

A number of laboratories have identified several key areas in the central nervous system that relay information from arterial baroreceptors to the supraoptic nucleus. Two of these regions are the diagonal band of Broca and the perinuclear zone of the supraoptic nucleus. Recent findings suggest that the inhibition of vasopressin neurons in the SON by caval-atrial stretch may also involve the perinuclear zone. Using Fos immunocytochemistry in combination with volume expansion in unanesthetized rats, we observed that volume expansion activates a number of regions in the CNS including the area postrema, the nucleus of the solitary tract, the caudal ventrolateral medulla, the paraventricular nucleus, the perinuclear zone and oxytocin neurons in the supraoptic nucleus. Further experiments using pericardial catheters demonstrate that the activation of the nucleus of the solitary tract, the ventrolateral medulla, the paraventricular nucleus and the perinuclear zone by volume expansion is dependent on cardiac afferents. However, the Fos in the area postrema and oxytocin neurons of the supraoptic nucleus is not affected by removal of cardiac afferents. Similarly, electrophysiological experiments show that stimulation of cardiac receptors in the caval-atrial junction inhibits supraoptic vasopressin neurons but does not significantly affect the activity of supraoptic oxytocin neurons. These experiments suggest that while the inhibition of supraoptic vasopressin neurons during volume expansion is mediated by cardiac afferents, the activation of supraoptic oxytocin is independent of cardiac afferents and may be mediated by other visceral afferents or humoral factors. Additional electrophysiological experiments examined the importance of the perinuclear zone in cardiopulmonary regulation of vasopressin. Excitotoxin lesions of the perinuclear zone region block the inhibitory effects of caval-atrial stretch on supraoptic vasopressin neurons. This lesion has previously been shown to block the inhibitory effects of arterial baroreceptor stimulation on supraoptic vasopressin neurons. Thus, the neural pathways that inhibit vasopressin release in response to an increase in blood pressure and an increase in blood volume may overlap at the perinuclear zone of the supraoptic nucleus. Also while the inhibition of supraoptic vasopressin neurons during volume expansion is mediated by cardiac afferents, the activation of supraoptic oxytocin neurons is independent of cardiac afferents and may be mediated by other visceral afferents or hormonal factors.

Intrapericardial procaine affects volume expansion-induced fos immunoreactivity in unanesthetized rats.

Acute volume expansion is associated with a specific pattern of Fos expression and the goal of the present study was to evaluate the contribution of cardiac receptors to this response. Adult male rats were instrumented with pericardial catheters introduced at the level of the thymus. Rats were also catheterized for measuring blood pressure, heart rate, central venous pressure, and intravenous infusion. Each rat received a 200-microl intrapericardial (i.p.c) injection of 2% procaine or 0.9% NaCl. Rats were then volume expanded with isotonic saline (10% body weight in 10 min) or given a control infusion (0.01 ml/min for 10 min). Ninety minutes after the start of the infusion, the rats were anesthetized and perfused transcardially. Their brains were sectioned and processed for Fos, dopamine-beta-hydroxylase, and oxytocin immunocytochemistry. Volume expansion plus i.p.c. saline produced a significant increase in Fos expression in the nucleus of the solitary tract, the ventrolateral medulla, the area postrema, the locus coeruleus, the paraventricular nucleus of the hypothalamus, the perinuclear zone of the supraoptic nucleus, and oxytocin neurons in the supraoptic nucleus. The i.p.c. procaine significantly blocked Fos expression produced by the volume expansion in the all of the regions examined except for the area postrema and the SON oxytocin neurons.

Wakeful positioning and movement controlling young infants: A pilot study.

Purpose: Clinical experience has suggested differences in motor development between infants nursed prone, and those nursed supine. This pilot study investigated possible associations between wakeful infant positioning and motor control. Method: Twenty-six infants were examined. Wakeful positional experience was recorded by log book. When the infants were aged between 14 and 18 weeks, motor control was measured using five items from the Movement Assessment of Infants. Results: Analyses revealed associations between age and time spent in stimulating circumstances, and some motor scores, but not an association between time spent in prone and supine positions and motor skills in those positions. Conclusion: Time spent in positions involving greater stimulation from, and closer interaction with, caregivers may be beneficial to motor development in early infancy.