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PubMed1992

Changing patterns of adolescent sexual behavior: consequences for health and development.

Sexuality is a fundamental quality of human life, important for health, happiness, individual development, and indeed for the preservation of the human race. During the dynamic period of adolescence in which the passage from childhood to maturity takes place, sexuality takes on new dimensions; feelings become more intense, relationships become more complex, and the consequences of sexual behavior are radically altered. This not only affects the behavior of young people but also of those who interact with them, their families and peers, and those who work in the health, education, youth, social welfare, and other sectors. In the contemporary world the conditions of life for many young people have also changed, and with it patterns of sexual behavior. In general, earlier puberty, later marriage, a decline in the family leading to less control and more autonomy, and intense exposure to sexual stimuli via the mass media and travel across cultural boundaries have made pre-marital adolescent sexual activity more common. This has added to traditional problems of early marriage, newer problems of early pregnancy, childbirth, and induced abortion outside of marriage, sexually transmitted diseases, and human immunodeficiency syndrome infection leading to acquired immunodeficiency syndrome. But the work of the World Health Organization (WHO), along with many others in the field, strongly suggests that given appropriate information and services, trust and equity between the sexes, young people will behave responsibly and well. In this paper some of the findings from methods developed by WHO for research, training, advocacy, and evaluation, and findings in relation to patterns and determinants of sexual and reproductive health and development will be described, and future directions suggested.

Adolescent↗
PubMed1993

Contraceptive self-efficacy in college women.

We examined the relationship between the theory of self-efficacy and its effect on contraceptive use along with other variables in a predominantly white female college population. Written survey questionnaires were administered to 356 subjects in college classrooms; the study sample was limited to those 250 female subjects who were age 17-25 years unmarried, and sexually active. The questionnaire was designed to measure contraceptive use, contraceptive self-efficacy, demographic variables, and other variables associated with the college psychosocial environment (i.e., alcohol use, history of sexual assault, and future orientation in education and career plans). Contraceptive self-efficacy (CSE) was highly correlated with effective use (r = .4, p < 0.01). Highly effective contraceptive users had a significantly higher mean CSE score (p < 0.01) than that of less effective users. Logistic regression analysis of effective contraceptive use resulted in a four-factor model that correctly classified 76.3% of users. Contraceptive self-efficacy was the most important predictor of contraceptive use for this sample. Lack of barriers to contraception was also important, with knowledge and length of time of sexual activity also included in the final regression model. Most demographic and future orientation variables were not significantly associated with effective use; variables measuring sexual experience and personal attitudes and perceptions about birth control were more significantly associated with effective use. A lack of interference from alcohol was highly associated with effective contraceptive use. Self-efficacy would seem to be important in predicting contraceptive use and effecting behavior change.

Adolescent↗
PubMed1997

Using the Kalman filter and dynamic models to assess the changing HIV/AIDS epidemic.

Many factors, including therapy and behavioral changes, have modified the course of the HIV/AIDS epidemic in recent years. To include these modifications in HIV/AIDS models, in the absence of appropriate external data sources, changes over time in the parameters can be incorporated by a recursive estimation technique such as the Kalman filter. The Kalman filter accounts for stochastic fluctuations in both the model and the data and provides a means to assess any parameter modifications included in new observations. The Kalman filter approach was applied to a simple differential model to describe the observed HIV/AIDS epidemic in the homo/bisexual male community in Paris (France). This approach gave quantitative information on the time-evolution of some parameters of major epidemiological significance (average transmission rate, mean incubation rate, and basic reproduction rate), which appears quite consistent with the recent epidemiological literature.

Disease Outbreaks↗
PubMed1995

A Drosophila seminal fluid protein, Acp26Aa, stimulates egg laying in females for 1 day after mating.

Mating triggers behavioral and physiological changes in the Drosophila melanogaster female, including an elevation of egg laying. Seminal fluid molecules from the male accessory gland are responsible for initial behavioral changes, but persistence of these changes requires stored sperm. Using genetic analysis, we have identified a seminal fluid protein that is responsible for an initial elevation of egg laying. This molecule, Acp26Aa, has structural features of a prohormone and contains a region with amino acid similarity to the egg-laying hormone of Aplysia. Acp26Aa is transferred to the female during mating, where it undergoes processing. Here we report the generation and analysis of mutants, including a null, in Acp26Aa. Females mated to male flies that lack Acp26Aa lay fewer eggs than do mates of normal males. This effect is apparent only on the first day after mating. The null mutation has no other detectable physiological or behavioral effects on the male or the mated female.

Amino Acid Sequence↗
PubMed1997

Altered gene expression in the host brain caused by a trematode parasite: neuropeptide genes are preferentially affected during parasitosis.

Schistosome parasites adjust the physiology and behavior of their intermediate molluscan hosts to their own benefit. Previous studies demonstrated effects of the avian-schistosome Trichobilharzia ocellata on peptidergic centers in the brain of the intermediate snail host Lymnaea stagnalis. In particular, electrophysiological properties and peptide release of growth- and reproduction-controlling neuroendocrine neurons were affected. We now have examined the possibility that the expression of genes that control physiology and behavior of the host might be altered during parasitosis. A cDNA library of the brain of parasitized Lymnaea was constructed and differentially screened by using mRNA from the brain of both parasitized and nonparasitized snails. This screening yielded a number of clones, including previously identified cDNAs as well as novel neuronal transcripts, which appear to be differentially regulated. The majority of these transcripts encode neuropeptides. Reverse Northern blot analysis confirmed that neuropeptide gene expression is indeed affected in parasitized animals. Moreover, the expression profiles of 10 transcripts tested showed a differential, parasitic stage-specific regulation. Changes in expression could in many cases already be observed between 1.5 and 5 hr postinfection, suggesting that changes in gene expression are a direct effect of parasitosis. We suggest that direct regulation of neuropeptide gene expression is a strategy of parasites to induce physiological and behavioral changes in the host.

Amino Acid Sequence↗
PubMed1990

Male knowledge of and attitudes and practices towards AIDS in Zimbabwe.

This paper presents findings from a survey on knowledge of and attitudes and practices towards AIDS among currently married Zimbabwean men conducted between April and June 1988. Findings indicated that knowledge was reasonably high: 89.7% reported having heard of AIDS. The young and middle-aged groups, the most educated, and the urban men were the most knowledgeable in identifying routes of transmission. However, 22% did not know that there could be asymptomatic carriers of the virus capable of transmitting the virus and infecting others. Furthermore, 38% did not know that all those affected with AIDS eventually die as a result, and only 55% knew that there is no cure for AIDS. Behavioral change in order to avoid contracting AIDS seems relatively low given this sample's history of sexually transmitted diseases and extramarital sexual relations during the year prior to the survey. Although condom use was the lowest percentage of the behavioral change categories, a high percentage reported ever using a condom.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Knowledge of AIDS among secondary school pupils in Bagamoyo and Dar-Es-Salaam, Tanzania.

We assessed knowledge of AIDS among pupils in selected schools in Tanzania in August 1989. Four hundred and eight-one pupils from four randomly selected secondary schools, two from Dar-Es-Salaam (a city) and two from Bagamoyo (a semi-rural town), were interviewed using a structured questionnaire. Of these, 476 (99.0%) had heard of AIDS, and 447 (92.9%) were able to mention spontaneously at least one sexually transmitted disease (STD), of whom 374 (83.7%) mentioned AIDS. Knowledge was found to increase with age and tended to be higher among women in Dar-Es-Salaam than in Bagamoyo. These data suggest that communication channels directed at women in rural areas should be strengthened. While knowledge of sexual transmission of HIV was generally high, and prevalence of reported misconceptions about modes of transmission was very low, knowledge of non-sexual means of transmission (transfusions, injections, vertical) was lacking. Although 80% of pupils mentioned reduction of number of sexual partners as a means of AIDS prevention, only 22% mentioned condom use, and less than 5% reported that they had ever used a condom. Future research should concentrate on means of promoting sexual behavior change, the ultimate aim of any AIDS prevention strategy.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Willingness to participate in AIDS vaccine trials among high-risk populations in northern Thailand.

OBJECTIVES: To determine the anticipated participation in a prophylactic AIDS vaccine trial and to identify perceived benefits and barriers to enrollment of HIV-seronegative volunteers at risk of HIV infection in northern Thailand. DESIGN: A cross-sectional survey. METHODS: Subjects interviewed in a cross-sectional survey included female commercial sex workers (n = 215), men attending sexually transmitted disease clinics (n = 219), conscripts in the Royal Thai Army (n = 1453), and men discharged from the army (n = 293) who had returned to civilian life. We determined AIDS vaccine knowledge and attitudes, perceived vulnerability to HIV infection, barriers and incentives to participate in a future vaccine trial and agreement to participate in a randomized trial. RESULTS: Awareness of vaccines (88-97%) and AIDS vaccine development efforts (62-77%) were common and viewed to be a complement to behavior change (74-94%). Approximately 25% of subjects would definitely join a trial if asked, and an additional 38% would accept an AIDS vaccine if they were convinced it would be safe and effective. Important barriers to participation included concerns with discrimination (16-45%), short- (37-60%) and long-term (30-55%) vaccine side-effects, fear of disability and death (36-58%), and beliefs that partners would refuse to have sex (24-49%) after immunization. The principal inducement to join a trial was health insurance (62%). CONCLUSION: Potential HIV vaccine trial participants have several fears of joining a vaccine study at this time. Information derived from Phase I/II trials is needed to address these concerns if enrollment in efficacy trials is to be successful in the near future.

AIDS Vaccines↗
PubMed1975

Intrauterine infection of mice with St. Louis encephalitis virus: immunological, physiological, neurological, and behavioral effects on progeny.

Intravenous injection of pregnant mice with St. Louis encephalitis (SLE) virus at 8 days of gestation resulted in infection of the fetus. Progeny developed no antibody or tolerance to SLE virus since the viral antigen was cleared by maternal antibody before antibody-forming competence developed in the young. Temporary growth retardation was observed in a number of young at 3 weeks of age. After the initial setback the growth rate increased, indicating that early runting was due to an inability to adjust adequately to extrauterine life, which was subsequently overcome. In most other young there were no significant effects on growth, reproduction, or life expectancy. A few young died at or shortly after birth; in these, neurological changes ranging from gross defects such as encephaloceles and hydrocephalus to histological evidence of necrosis and congestion were observed. Neurologically related behavioral changes were detected by using the open field test and the rotating-rod test, which indicated neurological damage and memory impairment in the surviving intrauterinely infected animals.

Animals↗
PubMed1992

Time and sex in the male mouse: temporal regulation of infanticide and parental behavior.

Infanticide is a violent but successful reproductive strategy found in many mammals, particularly rodents. In male house mice (Mus domesticus and M. musculus), the act of ejaculation provides a reliable neural signal for timing the birth of their offspring. However, a unique chronobiological aspect of this phenomenon is the extraordinary temporal latency that can occur between the stimulus (coital ejaculation) and its adaptive neural response (male mice cease killing pups and behave parentally toward them instead). Specifically, the inhibition of infanticide is often time delayed for many days after a male ejaculates, but virtually always occurs before or around the time his own sired offspring would be born 18-20 days later. Furthermore, infanticide spontaneously reemerges 50-60 days after mating. In CF-1 stock male mice this entire behavioral sequence is synchronized with the female's reproductive cycle, and occurs even in the total absence of social cues or changes in pituitary or gonadal hormones after mating. When entrained and mated at 22 h (light:dark 11:11) or 27 h (light:dark 13.5:13.5) T-cycles, photoperiodic cues appeared to synchronize this dramatic shift in behavior, because a sudden transition from pup killing to parenting was matched with the number of light/dark cycles experienced after ejaculation rather than the amount of real time experienced, suggesting a circadian timing link. Housing in constant light accelerated the postmating transition to parenting, whereas constant dark significantly delayed the transition to parenting, but still occurred by 3 weeks after mating. Most males tend to oscillate between infanticide and parental behavior for several days before locking in to constant parenting, regardless of lighting conditions. Variation in the time delay between ejaculation and the inhibition of infanticide was consistent within young individuals (< 10 months of age), but in older males (> 18 months of age) the time interval between ejaculation and parenting was significantly prolonged and attenuated. Another unique aspect of this phenomenon is that variation among individuals in their timing and response to light cues is correlated with phenotypic variation in sex steroid exposure during late fetal development. So far, no simple physiological explanation can account for the neural mechanism triggered by ejaculation that coordinates these time-delayed behavioral changes toward pups.

Animals↗
PubMed1999

The Women and Infants Demonstration Project: an integrated approach to AIDS prevention and research.

The Women and Infants Demonstration Project is a multisite, behavioral intervention research effort funded by the Centers for Disease Control. The project is evaluating a theory-based, integrated intervention model to increase the use of condoms for prevention of both sexually transmitted diseases (STDs) and unintended pregnancy among women and their partners at risk of infection with HIV. The importance of utilizing carefully targeted, credible and persistent risk reduction interventions to effect lasting behavior change has become evident over the last ten years of the AIDS epidemic. The theory-based intervention components being evaluated in this intervention study involve one-on-one stage-tailored outreach; the development and distribution of community-tailored HIV prevention materials, called role-model stories; and the development of organizational and peer networking, all within a community mobilization framework. This article describes each of the intervention components being evaluated during this 5-year study. Such an intervention effort represents an important contribution in the design of community-level AIDS prevention intervention efforts which support individual-level behavioral changes by women at risk for HIV and other sexually transmitted infections.

Adolescent↗
PubMed1988

The ethics of safe sex.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Project Redirection: evaluation of a comprehensive program for disadvantaged teenage mothers.

An evaluation of Project Redirection, a two-year demonstration program designed to help pregnant teenagers and teenage mothers, shows that teenagers from a comparison group, who were not enrolled in the demonstration program, were significantly more likely than project participants to experience a repeat pregnancy after one year, but that after two years the difference was small and nonsignificant. Likewise, at 12 months into the program, the project participants proved more likely to be using contraceptives, but by 24 months the comparison group had caught up. After one year of participation, the project teenagers were more likely than the others either to be in school or to have graduated (56 and 49 percent, respectively). However, this differential also disappeared by 24 months. Nonetheless, even at that point, project teenagers who had dropped out prior to joining the program and those who had had a repeat pregnancy were more likely to be in school or to have completed school than were similar comparison teens. Project teenagers also were somewhat more likely to have held a job during the two-year period than were teenagers not enrolled in the program. All in all, the evaluation demonstrated that teenagers who participated in the project and remained in it for more than a year had consistently better outcomes in education, employment and repeat pregnancy than any other group had. Comparison teenagers who had never participated in any special program for pregnant teenagers, on the other hand, demonstrated consistently poorer outcomes than any other group.

Adolescent↗
PubMed1979

Effects of chronic lead ingestion on social development in infant rhesus monkeys.

The social behavior of infant rhesus monkeys during the first year of life was examined under a variety of lead (Pb) exposure conditions in four separate experiments. Daily ingestion of PB acetate in milk for one year elevated blood Pb levels to 30-100 microgram/dl, suppressed play, increased social clinging, and exacerbated the disruption of social behavior caused by changing the play environment midway through the year of observation. The presence of control monkeys in social test-groups reduced the magnitude of Pb-induced social behavior changes. In contrast to daily postnatal Pb exposure, chronic exposure to Pb during gestation had no measurable effect on postnatal social development, and acute, transient postnatal Pb exposure (producing blood Pb levels > 200 microgram/dl during month 2 of life) affected only the monkeys' response to the change in the plan environment. These data suggest that daily ingestion of Pb, and not a previously-acquired tissue burden, was responsible for the long-term changes in social development observed. The results are discussed in the general context of primate social development, which is thought to require adequate interactive play for appropriate social integration and reproductive behavior at maturity.

Aging↗
PubMed1982

The development of menstrual-related beliefs and behaviors during early adolescence.

Adolescent girls' menstrual-related beliefs and behaviors are examined from a developmental perspective. 2 studies, 1 cross-sectional and 1 longitudinal, were conducted. In the first, 639 girls in grades 5-6, 7-8, and 11-12 were seen. In the second, 46 pairs of girls were seen twice: all were premenarcheal at the first testing; at the second testing, one-half had begun to menstruate in the last few months and one-half were a matched premenarcheal comparison group. Girls answered questions on menstrual symptomatology, menstrual-related attitudes, and potential informational sources. 3 questions were asked in the present study: (1) What are the expectations for menstrual symptoms that girls hold prior to menstruation and when do these develop? (2) How do expectations for menstrual symptoms and beliefs relate to the actual experience of menarche? (3) What are the sources of information for menstruation and do they relate to subsequent menstrual-related behavior? First, as early as fifth grade, premenarcheal girls had clear expectations regarding menstrual symptoms; their expectation that cycle-related changes would occur paralleled the changes reported by adult and older adolescent women. Second, girls who had begun to menstruate reported experiencing less severe menstrual distress (less pain, water retention, negative affect, and behavioral changes, and more concentration) than the premenarcheal comparison group expected to experience. In addition, early symptom expectations were positively related to later-reported menstrual distress (pain, water retention, and behavioral change) in the changing-menarcheal-status group. Third, there were few changes in the amount learned from various sources as a function of menarcheal status. However, correlational analyses indicate that girls who learned more from male sources rated menstruation as more debilitating and negative than those girls who learned less from male sources. The importance of socialization in the emergence of menstrual distress and negative menstrual attitudes is discussed.

Adolescent↗
PubMed1993

AIDS in sub-Saharan Africa: the epidemiology of heterosexual transmission and the prospects for prevention.

As the epidemic of the acquired immunodeficiency syndrome (AIDS) in sub-Saharan Africa enters its second decade, much has been learned about the distribution and determinants of the disease and its causative agent, the human immunodeficiency virus (HIV). Over 6 million people, or 2.5% of the adult population, are thought to be infected with HIV. The distribution of HIV is largely determined by sexual behavior; as for other sexually transmitted diseases, the characteristics of sexual networks determine the extent and rate of spread of HIV. Female sex workers and their male clients are at high risk for HIV and have been important in initiating the epidemic in many African countries. The dynamics of HIV in the rest of the population are complex; men with multiple sexual partners are largely responsible for transmission of HIV to women in the general population. Other sexually transmitted diseases and lack of male circumcision may increase the probability of transmission of HIV during sexual intercourse and probably are partially responsible for the rapid diffusion of HIV in Africa. Interventions among high-risk groups are needed, but they must be accompanied by attempts to induce behavior change among men and women in the general population. Epidemiologic studies of the determinants of sexual behavior and sexual contact patterns, as well the design and evaluation of interventions, are urgently needed. Key areas for development are the study of behavioral exposures and outcomes, the evaluation of interventions, developing new methods for conducting interventions in resource-poor environments, and increasing the number of African scientists with the skills and resources to conduct epidemiologic studies.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Influence of tapeworm infection on the production of aggregation pheromone and defensive compounds in Tribolium castaneum.

Recent studies suggest that parasites affect host development, reproduction, and behavior through alterations of host hormones and pheromones, or other hormone-triggered biochemical events. We previously reported that Hymenolepis diminuta infection affects surface-seeking and cannibalism behaviors, and reduces male sperm precedence of Tribolium castaneum beetles. This study examined the quantitative effects of H. diminuta on the production of aggregation pheromone and 3 defensive compounds in male T. castaneum beetles, using 2 wild-caught, geographically distinct T. castaneum strains. For the c-Madison strain, infected beetles exhibited a 2- to 22-fold increase in defensive compounds; conversely, no changes were observed in strain c-Africa. Parasite infection did not significantly influence aggregation pheromone secretion in either strain. Because defensive compounds function as repellents or deterrents to other insects, parasite-induced increases in the secretion of defensive compounds may be a physiologic clue for the behavioral changes in infected T. castaneum beetles. Significant among-strain variation in defensive compound production seen in infected beetles suggests that caution is needed before generalizing about changes in volatile production and in host behavior induced by a parasite.

Analysis of Variance↗