Virulence in rodent malaria: host genotype by parasite genotype interactions.

In an effort to understand what limits the virulence of malaria parasites, we infected inbred mice of three genotypes (C57Bl/6J, CBA/Ca and DBA/2) with one of two parasite lines of the rodent malaria Plasmodium chabaudi. One of these parasite lines had been serially passaged through C57Bl/6J mice and had evolved higher asexual growth rate, virulence and transmission in the process. The other parasite line was the unadapted ancestral line which had low virulence. In all three host genotypes, the C57Bl/6J-adapted parasite line was more virulent than the ancestral line thus indicating that trade-offs in virulence between alternative host genotypes had not placed strong constraints on the evolution of high virulence in this system. By examining the infection dynamics for fitness-related components-asexual parasite population growth, transmission and virulence-we revealed alternative possible explanations for what sets the upper limit to virulence in nature. The total number of transmission forms (gametocytes) produced during the infection, a measure of parasite Darwinian fitness, was four-fold higher in mice that survived the infection than those which died. Among mice that survived, total gametocyte production was greatest in the host genotype that suffered intermediate levels of morbidity (anaemia and weight loss). Thus, there were transmission costs of high virulence that were partly due to host death (as most theoretical models of virulence evolution assume), but perhaps partly due to some factor related to high morbidity. Both mortality and morbidity-related factors might therefore influence the upper limit on virulence of malaria parasites.     

性早熟女童血清睾酮与性激素结合球蛋白检测结果分析

目的了解特发性中枢性性早熟(ICPP)和单纯性乳房早发育(PT)女童血清睾酮(T)、游离睾酮(FT)和性激素结合球蛋白(SHBG)水平,为开展儿童青少年青春发育期研究提供参考。方法选取2000-2007年杭州师范大学附属医院儿科内分泌门诊诊治的ICPP和PT女童各16例为研究组,正常青春期女童和正常青春期前女童各16例为对照组。所有受试者采用放射免疫分析法测定血清T,FT,SHBG和雌二醇(E2),计算FT/T。结果 ICPP组与正常青春期女童组的E2和T水平高于PT组和正常青春期前女童组(P值均<0.05);PT组的FT水平和FT/T高于正常青春期女童组、ICPP组和正常青春期前女童组(P值均<0.05);PT组的SHBG水平低于正常青春期前女童组(P<0.05),而与ICPP组和正常青春期女童组差异无统计学意义(P>0.05)。结论女童PT与血清SHBG降低有关,具有生物活性的游离性激素的升高是导致女童发生PT的重要因素。血清FT的水平和FT/T有助于PT和ICPP的鉴别。     

Learning about sex: results from Natsal 2000.

To date, the focus of sex education research has tended to be on the effect of education on behavioral outcomes. There is little data on the felt needs of young people, how well they are met, and how provision might be improved. Here we report on main source of information about sexual matters, adequacy of knowledge, further needs, and preferred source of additional information, using data from a probability sample survey of people aged 16 to 44 years in Britain (Natsal 2000). A total of 11,161 participants (4,762 men and 6,399 women) were interviewed. The response rate was 65.4%. The results show that despite the assumed worldliness and sophistication of young people about sexual matters, there is a great deal of self-perceived ignorance among them. Parents and schools are the preferred source of further information. We need to enable parents to provide information to their children, especially their sons.     

The sexual behavior of US adults: results from a national survey.

OBJECTIVES. One consequence of the acquired immunodeficiency syndrome (AIDS) epidemic has been to highlight the need for population-based estimates of the number of individuals engaging in sexual behaviors that place them at risk for human immunodeficiency virus (HIV) infection. This paper describes the prevalence of various sexual behaviors in a nationally representative sample of adults in the United States. METHODS. Data were collected as part of a household probability survey of adults (n = 2058) in the United States. Data collected on sexual behavior included sexual orientation, frequency of intercourse, condom use, and number of sexual partners. RESULTS. Nearly all respondents were sexually experienced. Of those who were currently sexually active, 13% (1% of married respondents) had had sex with more than one partner in the previous year. Of those reporting having intercourse with more than one partner in the previous year, 7% used condoms consistently and 23% used condoms consistently with their casual partners. CONCLUSIONS. A significant proportion of individuals were found to have intercourse with multiple partners without using condoms. A minority of these respondents acknowledged that their behavior may place them at risk for HIV transmission.     

Multiple severe sexual dysfunctions resolved in brief sex therapy.

The following case illustrates the use of integrative sex therapy techniques in treating a couple with numerous sexual dysfunctions. The integrative method enables the therapist to address sexual difficulties in both partners simultaneously and significantly reduce the time of treatment.     

Mortality differences by APOE genotype estimated from demographic synthesis.

The 4 allele of apolipoprotein E (APOE) is associated with increased risk of two major causes of death in low-mortality populations: ischemic heart disease and Alzheimer's disease. It is less common among centenarians than at younger ages. Therefore, it is likely that it is associated with excess risk of death. This article extends demographic models that estimate relative mortality risks from changes in gene frequencies with age. The resulting demographic synthesis combines gene frequencies with data on mortality by genotype from cohort studies. The model was applied to data from Denmark, Finland, France, Italy, Sweden, and the United States. Near age 50, the 3/4 genotype is associated with a risk of death of 1.34 times that of the 3/3 (95% CI 1.18-1.67). The relative risk for 4/4 is the square of the relative risk for 3/4, 1.81. The 2/3 genotype is protective with a relative risk of 0.84 (0.68-0.93) near age 50. These relative risks move toward 1.0 at the oldest ages and APOE genotype is associated with little variation in mortality over age 100. There are no significant differences in the relative risks by sex. There is little evidence of differences within Europe in the effects of APOE. This approach can be generalized to combine data on genetic risk factors for disease from a wide variety of study designs and sample characteristics.     

Differential responses to selenomethionine supplementation by sex and genotype in healthy adults

A year-long intervention trial was conducted to characterise the responses of multiple biomarkers of Se status in healthy American adults to supplemental selenomethionine (SeMet) and to identify factors affecting those responses. A total of 261 men and women were randomised to four doses of Se (0, 50, 100 or 200 μg/d as L-SeMet) for 12 months. Responses of several biomarkers of Se status (plasma Se, serum selenoprotein P (SEPP1), plasma glutathione peroxidase activity (GPX3), buccal cell Se, urinary Se) were determined relative to genotype of four selenoproteins (GPX1, GPX3, SEPP1, selenoprotein 15), dietary Se intake and parameters of single-carbon metabolism. Results showed that supplemental SeMet did not affect GPX3 activity or SEPP1 concentration, but produced significant, dose-dependent increases in the Se contents of plasma, urine and buccal cells, each of which plateaued by 9-12 months and was linearly related to effective Se dose (μg/d per kg0·75). The increase in urinary Se excretion was greater for women than men, and for individuals of the GPX1 679 T/T genotype than for those of the GPX1 679 C/C genotype. It is concluded that the most responsive Se-biomarkers in this non-deficient cohort were those related to body Se pools: plasma, buccal cell and urinary Se concentrations. Changes in plasma Se resulted from increases in its non-specific component and were affected by both sex and GPX1 genotype. In a cohort of relatively high Se status, the Se intake (as SeMet) required to support plasma Se concentration at a target level (Se(pl-target)) is: Se(in) = [(Se(pl - target) - Se(pl))/(18.2ng d kg?.??/ml per mu g)] .     

Utilisation of sexual health services by female sex workers in Nepal

Background  

The Nepal Demographic Health Survey (NDHS) in 2006 showed that more than half (56%) of the women with sexually transmitted infections (STIs), including HIV, in Nepal sought sexual health services. There is no such data for female sex workers (FSWs) and the limited studies on this group suggest they do not even use routine health services. This study explores FSWs use of sexual health services and the factors associated with their use and non-use of services.     

The inheritance of pyloric stenosis explained by a multifactorial threshold model with sex dimorphism for liability

The inheritance of pyloric stenosis is explained by a multifactorial threshold model with an underlying assumption that the liability for the disease is distributed in males and females showing a sex dimorphism. From the available data on familial occurrences of pyloric stenosis, it is shown, that an extra maternal effect is not required to explain the familial risk of pyloric stenosis, as opposed to the earlier literature. Explicit expressions for familial risks of a discontinuous trait exhibiting dimorphism of liability are presented, based on a model originally proposed by Rice et al [1981], which do not require the approximation of univariate normality of a conditional bivariate normal distribution.     

Adolescents' perceptions of maternal disapproval of sex: relationship to sexual outcomes.

PURPOSE: To examine the relationship between adolescents' perceptions of maternal abstinence attitudes, adolescent-maternal relationship satisfaction, and the occurrence in the ensuing 12 months of: (a) sexual intercourse, (b) the use of birth control at intercourse, and (c) the occurrence of pregnancy. We also examined the accuracy of adolescents in perceiving the attitudes of their mothers as well as factors that predicted underestimations of these attitudes. Finally, the study evaluated the relative predictive power of adolescent perceptions of maternal abstinence attitudes and the actual maternal abstinence attitudes. METHODS: This was a prospective study using a subsample of the Longitudinal Study of Adolescent Health database, which is a nationally representative school-based sample. The sample for the present study was approximately 10,000 adolescents in grades 7 to 11 who completed 2 interviews in their homes at a 1-year interval. Mothers of the adolescents were interviewed only during Wave 1. Interviews covered a variety of topics, including adolescent risk behaviors and family relationships. Measures at Wave 1 were used to predict outcomes at Wave 2, employing logistic and multiple regression techniques. RESULTS: Adolescents' perceptions of maternal attitudes toward the adolescents' engaging in sexual intercourse, and adolescent satisfaction with the maternal relationship were predictive of the occurrence of sexual intercourse between Wave 1 and Wave 2, as well as the occurrence of pregnancy. The more disapproving adolescents perceived their mothers to be toward their engaging in sexual intercourse and the more satisfied adolescents were with their relationship with their mothers, the less likely adolescents were to initiate sexual activity or to become pregnant. Only relationship satisfaction was predictive of the use of birth control, such that more satisfied adolescents were more likely to use birth control at their most recent intercourse. The correlation between adolescent perceptions of maternal abstinence attitudes and actual maternal attitudes was .26. Adolescent perceptions of maternal attitudes tended to be a more consistent predictor of outcomes than actual maternal attitudes. CONCLUSIONS: The results are consistent with a growing body of literature that suggests the importance of adolescents' perceptions of maternal attitudes in determining sexual risk behaviors. Adolescents may misperceive the attitudes of parents, suggesting the need for communication between parent and teen.     

HIV阳性结果告知对男男性行为者高危性行为的影响

目的了解HIV阳性结果告知对男男性行为者(MSM)行为改变的影响。方法 2011年1月-2012年12月,对1 365名MSM进行问卷调查和梅毒快速血浆反应素环状卡片试验(RPR)、梅毒螺旋体血球凝集试验(TPPA)、艾滋病病毒(HIV)抗体初筛检测及确认,对121名HIV确认阳性者进行规范面对面告知,6个月后对纳入研究的HIV阳性者进行随访,比较阳性结果告知前后艾滋病(AIDS)知识知晓、高危性行为特征及性病感染情况。结果 79名MSM完成随访,阳性结果告知后51.9%的感染者减少了肛交行为,49.4%的减少了性伴数,55.7%的在性行为时安全套使用率提高,告知前后肛交行为、多性伴、不使用安全套等高危性行为发生率,差异均有统计学意义(P0.05)。结论阳性结果告知能有效降低MSM人群高危性行为发生率,应加强告知的规范性,确保告知的效果。     

性心理健康视角下对青春期学生系统开展性教育的实效性

  目的  比较从性认知、性价值观以及性适应等方面对青春期学生系统开展性教育的具体作用,为在中学开展全面性教育提供实践支持。  方法  采取整群抽样的方法,抽取四川省6所普通中学及职业中学的3 369名初中及高中学生,分为系统开展性教育的学校以及非系统开展性教育学校,采用青春期性心理健康量表进行调查研究。  结果  接受系统教育的青春期学生与非系统性教育学生的性认知(7.54±1.41,7.20±1.66)、性价值观(7.60±1.17,7.30±1.24)、性适应(11.49±1.29,11.10±1.41)差异均有统计学意义(t值分别为5.95,6.80,7.57,P值均 < 0.01)。在初中阶段接受过系统性教育的学生在性认知、性价值观和性适应方面均高于接受非系统性教育的学生(P值均 < 0.01)。但在高中阶段,系统性教育的差异仅仅表现在性价值观总分、性观念、性控制力以及性适应中的自身适应等方面(P值均 < 0.01)。而接受系统性教育和非系统性教育的男女生在性认知、性价值观和性适应等方面差异均有统计学意义(P值< 0.01)。  结论  相比非系统地开展学校性教育,系统的性教育更有利于青春期学生的性心理健康。     

Child sexual abuse and subsequent psychopathology: results from the National Comorbidity Survey

OBJECTIVES: This study examined the relationship between child sexual abuse (CSA) and subsequent onset of psychiatric disorders, accounting for other childhood adversities, CSA type, and chronicity of the abuse. METHODS: Retrospective reports of CSA, other adversities, and psychiatric disorders were obtained by the National Comorbidity Survey, a nationally representative survey of the United States (n = 5877). Reports were analyzed by multivariate methods. RESULTS: CSA was reported by 13.5% of women and 2.5% of men. When other childhood adversities were controlled for, significant associations were found between CSA and subsequent onset of 14 mood, anxiety, and substance use disorders among women and 5 among men. In a subsample of respondents reporting no other adversities, odds of depression and substance problems associated with CSA were higher. Among women, rape (vs molestation), knowing the perpetrator (vs strangers), and chronicity of CSA (vs isolated incidents) were associated with higher odds of some disorders. CONCLUSIONS: CSA usually occurs as part of a larger syndrome of childhood adversities. Nonetheless, CSA, whether alone or in a larger adversity cluster, is associated with substantial increased risk of subsequent psychopathology.     

Psycho-social determinants for sexual partner referral in Uganda: quantitative results.

The purpose of this study was to investigate the factors influencing sexual partner referral using the Attitude-Social influence self-Efficacy model as a guiding theoretical framework. The data was collected in an interview survey with 236 women and 190 men attending a sexually transmitted disease clinic in Kampala, Uganda. Intention, attitude, subjective norm, self-efficacy, and past behaviour in relation to partner referral as well as partner type were collected at time 1. At time 2 (1 month later), sexual partner referral was assessed. Intention, self-efficacy, and previous behaviour predicted partner referral for women whereas intention, partner type and previous behaviour predicted partner referral for men. For the women the strongest predictors for intention were self-efficacy followed by attitude and partner type. For the men the strongest predictor was attitude followed by partner type and self-efficacy. Social influence was a better predictor of intention for women than for men. An analysis of underlying cognitive beliefs discriminating those who referred and those who did not refer the sexual partner showed that attitudinal beliefs were the most important for men whereas self-efficacy beliefs were the most important for women. The targeting of the gender-based discriminatory beliefs in intervention may improve compliance with sexual partner referral.     

Extramarital sex and HIV risk behavior among US adults: results from the National AIDS Behavioral Survey.

Data from the National AIDS Behavioral Survey were used to examine the social distribution of extramarital sex and risk for human immunodeficiency virus (HIV) infection among married individuals in the United States. Of 1686 married respondents living across the United States, 2.2% reported extramarital sex; of 3827 married respondents living in 23 urban areas with large Hispanic or African-American populations, 2.5% reported having sexual partners outside marriage. The data indicate that the correlates of extramarital sex varied by race/ethnicity. Low levels of condom use were found among people reporting extramarital sex (8% to 19% consistent users).     

Men''s disclosure of HIV test results to male primary sex partners.

We evaluated disclosure of human immunodeficiency virus (HIV) antibody status to a main sex partner and the impact on the relationship in men who have sex with men and who are enrolled in the Acquired Immunodeficiency Syndrome (AIDS) Community Demonstration Projects cohorts. Eighty-nine percent of both seronegative and seropositive men disclosed the results to their main sex partner. Seventy percent of the seronegative men and 82% of the seropositive men who did so reported that the relationship remained "as strong as ever" after 6 months. Most men who did not disclose their test results to their main partner reported being "single" after 6 months.     

Placenta praevia and male sex at birth: results from a population-based study

This study examined the relationship between male sex at birth and placenta praevia in 433031 mother/infant dyads (linked by a common institutional code and hospital admission number) in the Canadian province of Quebec, during the fiscal years of 1991/92-1995/96. The male-to-female ratio among pregnancies with and without placenta praevia was calculated and compared. The male-to-female ratio at birth was higher in pregnancies complicated by a placenta praevia (1.19) than in those without it (1.04; P < 0.02). This increased ratio persisted after accounting separately for the potential confounding and/or modifying effects of maternal age, infant birthweight and gestational age by stratified and multiple logistic regression analyses. We conclude that pregnant women with male babies carry a higher risk of placenta praevia.