Knowledge, attitudes and behaviours related to HIV and AIDS among chinese adolescents in hong kong.

The purpose of this study was to assess HIV and AIDS knowledge and attitudes, source of HIV and AIDS information, and behaviours related to HIV and AIDS among Chinese adolescents in Hong Kong. Participants included 1259 (826 females and 433 males) Chinese adolescents in Hong Kong between 12-18 years of age. Findings revealed that over 80% of the adolescents had rarely or never discussed HIV and AIDS with their family or teacher, and the primary source of HIV and AIDS information was media sources such as television and newspapers. Findings revealed HIV and AIDS misinformation among both male and female adolescents in the areas of transmission, facts, personal vulnerability and attitudes. However, participants reported engaging in little at-risk behaviour associated with HIV and AIDS. Implications for HIV and AIDS education and prevention are discussed.

Influence of perinatal factors on the nucleus accumbens dopamine response to repeated stress during adulthood: an electrochemical study in the rat.

Evidence from animal studies suggests that a period of anoxia to the fetus, a consequence common to many birth complications, results in long-term alterations in ventral mesencephalic dopamine function. Long-term functional changes in these dopamine neurons, in particular those that innervate the nucleus accumbens, also occur when animals are repeatedly stressed. In the present study, we examined the possibility that a period of anoxia during a Cesarean section birth can later alter the development of stress-induced sensitization of dopamine transmission in the nucleus accumbens. Dams were decapitated on the last day of gestation and the entire uterus was removed by Cesarean section. Pups were then delivered either immediately (Cesarean section group) or were immersed in a 37 degrees C saline bath for 3.5 or 13.5 min (Cesarean section+anoxia groups) before delivery of the pups. A fourth group of pups that were born vaginally served as controls (Vaginal group). Three to four months postnatally, animals from each group were implanted with monoamine-selective carbon-fiber electrodes into the nucleus accumbens. Voltammetry was used to monitor the dopamine response to each of five consecutive, once daily, 15-min exposures to tail-pinch stress. The results show that the first exposure to stress elicited dopamine signal increases of comparable amplitudes and durations in all animals. However, when compared to the initial stress response, the fourth and fifth exposures to tail-pinch elicited significantly longer-lasting dopamine responses in animals born by Cesarean section, either with or without added anoxia. In contrast, there was no significant day-to-day enhancement of the stress response in control, vaginally born animals. The findings reported here provide experimental support for the idea that birth complications may contribute to the pathophysiology of psychiatric disorders, in particular those that involve central dopamine dysfunction, such as schizophrenia. Specifically, our results suggest that subtle alterations in birth procedure may be sufficient to increase the sensitivity of mesolimbic dopamine neurons to the effects of repeated stress in the adult animal.

Electrochemical evidence of increased dopamine transmission in prefrontal cortex and nucleus accumbens elicited by ventral tegmental mu-opioid receptor activation in freely behaving rats.

Chronoamperometry was used in combination with monoamine-selective electrodes to monitor, in nucleus accumbens (NAcc) and prefrontal cortex (PFC) of freely behaving rats, changes in dopamine (DA)-like electrochemical signals elicited by unilateral ventral tegmental microinjections of the selective mu-opioid receptor agonist D-Ala, N-Me-Phe-Gly-Ol-Enkephalin (DAMGO; 0.01, 0.1, and 1.0 nmol). The results show that DAMGO dose-dependently increased electrochemical signals both in Nacc and PFC within a few minutes of injection. While DAMGO elicited signal increases of comparable amplitudes in both regions, the increases recorded in PFC were significantly longer lasting than those in NAcc; at the highest dose tested (1.0 nmol), DAMGO produced signal increases that lasted (mean +/- sem) 129 +/- 7.3 min in PFC and 96 +/- 12.5 min in NAcc. Pretreatment with the opioid receptor antagonist, naloxone (2 mg/kg, sc), significantly attenuated the peak amplitude and reduced the duration of DAMGO-induced (0.1 nmol) signal increases both in PFC and NAcc. In contrast, pretreatment with apomorphine (50 micrograms/kg, sc), a D1/D2 DA receptor agonist, significantly reduced the duration and the rate of rise of the signal increases in both regions but had little effect on the peak increases in signal. Unilateral ventral tegmental DAMGO administration (0.01, 0.1, and 1.0 nmol) also caused dose-dependent increases in contraversive circling the duration of which approximated that of the signal increases recorded in NAcc. However, differences in the time courses of DAMGO-induced contraversive circling and signal increases in NAcc suggest that the behavioral stimulant effect of ventral tegmental mu-opioid receptor activation may not be mediated exclusively by meso-NAcc DA neurons. The results of this study suggest that enkephalins modulate the activity of meso-PFC DA neurons and that behaviorally relevant activation of mu-opioid receptors in the ventral tegmental area increases DA transmission in PFC to a same, if not to a greater extent as in NAcc. These findings are discussed in relation to evidence indicating that the response of meso-NAcc DA neurons to a variety of stimuli, including drugs of abuse, is indirectly regulated by a DA-sensitive neurons in PFC.

Ventral tegmental injections of a selective mu or delta opioid enhance feeding in food-deprived rats.

Food-deprived rats received injections of the selective mu opioid D-Ala2,N-Me-Phe4-Gly5-Ol-Enkephalin (DAMGO; 0.01, 0.1, 1.0 or 10 nmol) or the selective delta opioid D-Pen2,D-Pen5-enkephalin (DPDPE; 0.1, 1.0 or 10 nmol) into or dorsal to the ventral tegmental area (VTA). Repeated measures of the speed of eating and the latency to initiate eating were obtained by dividing meals into discrete segments. Intra-VTA injections of DAMGO or DPDPE produced dose-dependent increases in the speed of eating but had little effect on the latency to initiate eating. Injections into sites dorsal to the VTA were ineffective in the case of DPDPE and less than normally effective in the case of DAMGO. Intra-VTA DAMGO was at least 100 x more potent in enhancing feeding than was DPDPE. A similar difference in potency has been observed in the degree to which DAMGO or DPDPE activates the mesolimbic dopamine system. These data suggest the possibility that changes in the mesolimbic dopamine system underlie the potentiation of feeding by intra-VTA administration of mu or delta opioids.

Ventral tegmental area opioid mechanisms and modulation of ingestive behavior.

In this paper we report on the effects of intra-VTA infusion of opioid agonists on rat ingestive behavior in a variety of experimental contexts. When the animals were tested outside of their home cages surrounded only by food-pellets (Experiment 1), the injection of the mu-opioid agonist DAMGO, but not the kappa-opioid agonist U-50,488H, into the ventral tegmental area facilitated food-related behaviors, decreasing the latency to feed and increasing the number of interactions with food. When, as in Experiment 2, gnawable objects and a drinking tube were also available, intra-VTA DAMGO gnawing and drinking behaviors, whereas the effects on feeding were negligible. These effects intra-VTA DAMGO increased were greatly enhanced in rats that underwent repeated treatments with amphetamine. On the other hand, when food-related behaviors were studied in a home-cage, where access to the food supply was achieved by entry into a tunnel, latency to feed and total food-intake were not enhanced in tests made during either the dark or the light phase (Experiment 3 and 4). This was true whether powdered standard lab chow or a highly palatable food was available. It appears that when a number of alternative incentive stimuli are available, increases in dopamine transmission such as that induced by intra-VTA DAMGO may ultimately have the effect of interfering with behavior normally directed primarily to one of these stimuli, by enhancing the salience of others. These effects bears some resemblance to the effects of tail-pinch and electrical brain stimulation of the medial forebrain bundle-lateral hypothalamic area on the responses to natural incentive stimuli.

Ventral tegmental injections of morphine but not U-50,488H enhance feeding in food-deprived rats.

Food-deprived rats received microinjections of the preferential mu opiate morphine or the selective kappa opiate U-50,488H (0.1, 1 and 10 nmol) into the ventral tegmental area (VTA). Meals were divided into discrete segments so that repeated measures of the speed of eating and the latency to initiate eating could be obtained. Morphine produced a dose-dependent increase in the speed of eating. Injections of saline or U-50,488H into the VTA or injections of morphine dorsal to the VTA were ineffective. Neither morphine nor U-50,488H had a significant effect on the latency to initiate feeding. These data suggest that mu but not kappa opioid receptors in the VTA are involved in the regulation of feeding in food-deprived rats.

Effects of systemic and central prolactin injections on food intake, weight gain, and estrous cyclicity in female rats.

It has been suggested that prolactin may contribute to the hyperphagia of lactation. Studies examining the effects of the systemic administration of prolactin on food intake, however, have produced varying results. In species other than the rat, central prolactin administration has been found to increase food intake, but it is not known if central prolactin administration increases food intake in rats. In the current study the effects of peripheral and central prolactin administration on food intake, weight gain, and estrous cyclicity in female rats were compared. Prolactin was administered twice daily at 0800 and at 1900 h either subcutaneously at 3 mg/kg or 1 mg/kg b.wt. or by intracerebroventricular (ICV) infusion (2 micrograms/0.5 microliter) for 10 days to female rats. Control animals received similar injections of vehicle. Food intake, body weight, and vaginal smears were taken daily. Results showed that peripheral administration of prolactin increased food intake and weight gain and disrupted vaginal cyclicity. In contrast, ICV administration increased food intake to the same extent as did systemic prolactin administration but had no effect on weight gain or cyclicity. These data suggest that prolactin acts both peripherally and centrally to regulate energy balance in the female rat.

Dietitians' role in decisions to withhold nutrition and hydration.

Decisions to limit nutrition and hydration in irreversibly or terminally ill patients are becoming more frequent in both hospitals and home-care settings. Although clear-cut principles or rules are not always possible, appropriate decisions about any form of life-sustaining treatment, nutrition and hydration included, require conducting a productive moral conversation within the medical management team and/or the institutional ethics committee. In this article, we discuss how dietitians can participate in these medical decisions.

New dimensions: the dietitian in private practice.

Private practice is coming to the fore in the profession of dietetics. It can serve as a much needed arm of the health care delivery system in the area of nutrition. Institutions need to re-evaluate and expand their opportunities to sue private practioners, thus releasing more employee time for short-term remedial counseling and education. Referral processes need to be designed and implemented to open new opportunities for consumers to choose and obtain continuing services. Private practice must be included in funding methods, such as third-party payment. Educationl institutions must design programs to prepare persons for private practice. The profession must solve the problem of obtaining community recognition of properly qualified professional authority. The profession must also support the concept of a lifetime career in direct private practice and plan career tracks to keep the most able practioners available to consumers.