Sexual dimorphism of the femoral neck during the adolescent growth spurt: a structural analysis

Before puberty, there are only small sex differences in body shape and composition. During adolescence, sexual dimorphism in bone, lean, and fat mass increases, giving rise to the greater size and strength of the male skeleton. The question remains as to whether there are sex differences in bone strength or simply differences in anthropometric dimensions. To test this, we applied hip structural analysis (HSA) to derive strength and geometric indices of the femoral neck using bone densitometry scans (DXA) from a 6-year longitudinal study in Canadian children. Seventy boys and sixty-eight girls were assessed annually for 6 consecutive years. At the femoral neck, cross-sectional area (CSA, an index of axial strength), subperiosteal width (SPW), and section modulus (Z, an index of bending strength) were determined, and data were analyzed using a hierarchical (random effects) modeling approach. Biological age (BA) was defined as years from age at peak height velocity (PHV). When BA, stature, and total-body lean mass (TB lean) were controlled, boys had significantly higher Z than girls at all maturity levels (P < 0.05). Controlling height and TB lean for CSA demonstrated a significant independent sex by BA interaction effect (P < 0.05). That is, CSA was greater in boys before PHV but higher in girls after PHV The coefficients contributing the greatest proportion to the prediction of CSA, SPW, and Z were height and lean mass. Because the significant sex difference in Z was relatively small and close to the error of measurement, we questioned its biological significance. The sex difference in bending strength was therefore explained by anthropometric differences. In contrast to recent hypotheses, we conclude that the CSA-lean ratio does not imply altered mechanosensitivity in girls because bending dominates loading at the neck, and the Z-lean ratio remained similar between the sexes throughout adolescence. That is, despite the greater CSA in girls, the bone is strategically placed to resist bending; hence, the bones of girls and boys adapt to mechanical challenges in a similar way. (C) 2004 Elsevier Inc. All rights reserved.

Expression profiling of purified mouse gonadal somatic cells during the critical time window of sex determination reveals novel candidate genes for human sexual dysgenesis syndromes

Despite the identification of SRY as the testis-determining gene in mammals, the genetic interactions controlling the earliest steps of male sex determination remain poorly understood. In particular, the molecular lesions underlying a high proportion of human XY gonadal dysgenesis, XX maleness and XX true hermaphroditism remain undiscovered. A number of screens have identified candidate genes whose expression is modulated during testis or ovary differentiation in mice, but these screens have used whole gonads, consisting of multiple cell types, or stages of gonadal development well beyond the time of sex determination. We describe here a novel reporter mouse line that expresses enhanced green fluorescent protein under the control of an Sf1 promoter fragment, marking Sertoli and granulosa cell precursors during the critical period of sex determination. These cells were purified from gonads of male and female transgenic embryos at 10.5 dpc (shortly after Sry transcription is activated) and 11.5 dpc (when Sox9 transcription begins), and their transcriptomes analysed using Affymetrix genome arrays. We identified 266 genes, including Dhh, Fgf9 and Ptgds, that were upregulated and 50 genes that were downregulated in 11.5 dpc male somatic gonad cells only, and 242 genes, including Fst, that were upregulated in 11.5 dpc female somatic gonad cells only. The majority of these genes are novel genes that lack identifiable homology, and several human orthologues were found to map to chromosomal loci implicated in disorders of sexual development. These genes represent an important resource with which to piece together the earliest steps of sex determination and gonad development, and provide new candidates for mutation searching in human sexual dysgenesis syndromes.

The makings of maleness: towards an integrated view of male sexual development

As the mammalian embryo develops, it must engage one of the two distinct programmes of gene activity, morphogenesis and organogenesis that characterize males and females. In males, sexual development hinges on testis determination and differentiation, but also involves many coordinated transcriptional, signalling and endocrine networks that underpin the masculinization of other organs and tissues, including the brain. Here we bring together current knowledge about these networks, identify gaps in the overall picture, and highlight the known defects that lead to disorders of male sexual development.

PERSONALIDADE, ESTILOS PARENTAIS E COGNIÇÃO EM MENINOS VÍTIMAS DE ABUSO SEXUAL

Há um consenso na literatura de que a vivência do abuso sexual na infância ocasiona uma série de consequências, tanto físicas quanto psicológicas, às vítimas. O cenário de violência contra crianças e adolescentes está cada vez mais frequente na sociedade contemporânea, tornando-se um problema de saúde pública, de modo a ser necessário um olhar mais atento dos profissionais e elaboração de políticas públicas tanto para a prevenção dos casos como para o tratamento dos problemas deles decorrentes. Nas crianças, há uma associação do aumento de problemas comportamentais e psicológicos, que podem se estender até o período da idade adulta. Outros estudos enfatizam alterações em áreas cerebrais e as relacionam com o surgimento de transtornos mentais na população de crianças vítimas de violência sexual, dentre outros tipos de violência. O objetivo deste trabalho foi verificar a presença de traços de personalidade, os estilos parentais desenvolvidos e o desempenho cognitivo, especificamente as funções executivas, em meninos com histórico de abuso sexual. Foram avaliadas 62 crianças e adolescentes (32 com histórico de abuso sexual e 30 sem), sendo que no grupo de abuso a idade média dos integrantes é de 11,7 anos de idade e seus genitores majoritariamente divorciados, diferentemente do grupo controle, no qual os genitores são, na maior parte, casados. O método constou de questionário sociodemográfico, testes neuropsicológicos que avaliam as funções executivas (Wisconsin Card Sortint Test, Figuras de Ray e Escala de Inteligência Wechsler para Crianças - Terceira Edição (WISC-III)- Semelhanças, Arranjo de Figuras, Compreensão, Cubos, Dígitos e Vocabulário), Questionário de Personalidade para Crianças e Adolescentes (EPQ-J) e Inventário de Estilos Parentais (IEP). Não houve resultados significativos entre o abuso e as funções executivas, tanto nos subtestes dos Escala de Inteligência Wechsler para Crianças - Terceira Edição (WISC-III) quanto no do Wisconsin; porém o grupo apresentou dados significativamente menores na memória do Figuras Complexas de Rey. Com relação ao EPQ-J, os resultados demonstraram maiores índices de neuroticismo, os quais podem ser associados com sintomas de depressão, e apresentaram menores índices em extroversão, trazendo possíveis dificuldades nas relações sociais. Com relação aos estilos parentais, o grupo apresentou dificuldades e prejuízos nas percepções sobre os genitores, especialmente com relação ao genitor, que é o maior abusador estatisticamente. Os dados mostraram uma correlação entre neuroticismo e vocabulário, estilos parentais e vocabulário, e neuroticismo e estilos parentais. Observou-se a importância de maiores estudos com o público masculino, para que possam ser elucidadas, de forma mais abrangente, as questões de abuso sexual e suas interferências nos aspectos neuropsicológicos, estilos parentais e traços de personalidade, visto que a maior parte dos estudos é relacionada ao público feminino. É necessário o desenvolvimento de políticas públicas para o atendimento específico do público masculino que sofre abuso, e que o profissional da saúde esteja preparado para ajudar, fortalecendo os aspectos psíquicos e emocionais.

Placental contribution to the origins of sexual dimorphism in health and diseases: sex chromosomes and epigenetics

Sex differences occur in most non-communicable diseases, including metabolic diseases, hypertension, cardiovascular disease, psychiatric and neurological disorders and cancer. In many cases, the susceptibility to these diseases begins early in development. The observed differences between the sexes may result from genetic and hormonal differences and from differences in responses to and interactions with environmental factors, including infection, diet, drugs and stress. The placenta plays a key role in fetal growth and development and, as such, affects the fetal programming underlying subsequent adult health and accounts, in part for the developmental origin of health and disease (DOHaD). There is accumulating evidence to demonstrate the sex-specific relationships between diverse environmental influences on placental functions and the risk of disease later in life. As one of the few tissues easily collectable in humans, this organ may therefore be seen as an ideal system for studying how male and female placenta sense nutritional and other stresses, such as endocrine disruptors. Sex-specific regulatory pathways controlling sexually dimorphic characteristics in the various organs and the consequences of lifelong differences in sex hormone expression largely account for such responses. However, sex-specific changes in epigenetic marks are generated early after fertilization, thus before adrenal and gonad differentiation in the absence of sex hormones and in response to environmental conditions. Given the abundance of X-linked genes involved in placentogenesis, and the early unequal gene expression by the sex chromosomes between males and females, the role of X- and Y-chromosome-linked genes, and especially those involved in the peculiar placenta-specific epigenetics processes, giving rise to the unusual placenta epigenetic landscapes deserve particular attention. However, even with recent developments in this field, we still know little about the mechanisms underlying the early sex-specific epigenetic marks resulting in sex-biased gene expression of pathways and networks. As a critical messenger between the maternal environment and the fetus, the placenta may play a key role not only in buffering environmental effects transmitted by the mother but also in expressing and modulating effects due to preconceptional exposure of both the mother and the father to stressful conditions.

Sexual risk behaviors and HIV risk among Americans aged 50 years or older: a review.

Although HIV-related sexual risk behaviors have been studied extensively in adolescents and young adults, there is limited information about these behaviors among older Americans, which make up a growing segment of the US population and an understudied population. This review of the literature dealing with sexual behaviors that increase the risk of becoming HIV-infected found a low prevalence of condom use among older adults, even when not in a long-term relationship with a single partner. A seminal study by Schick et al published in 2010 reported that the prevalence of condom use at last intercourse was highest among those aged 50-59 years (24.3%; 95% confidence interval, 15.6-35.8) and declined with age, with a 17.1% prevalence among those aged 60-69 years (17.1%; 95% confidence interval, 7.3-34.2). Studies have shown that older Americans may underestimate their risk of becoming HIV-infected. Substance use also increases the risk for sexual risk behaviors, and studies have indicated that the prevalence of substance use among older adults has increased in the past decade. As is the case with younger adults, the prevalence of HIV infections is elevated among ethnic minorities, drug users (eg, injection drug users), and men who have sex with men. When infected, older adults are likely to be diagnosed with HIV-related medical disorders later in the course of illness compared with their younger counterparts. Physicians are less likely to discuss sexual risk behaviors with older adults and to test them for HIV compared with younger adults. Thus, it is important to educate clinicians about sexual risk behaviors in the older age group and to design preventive interventions specifically designed for older adults.

Child Abuse and Mental Disorders in Iranian Adolescents

Background: Child abuse is a serious social health problem all over the world with important adverse effects. Objectives: The aim of this study was to extend our understanding of the relation between mental disorders and child abuse. Materials and Methods: The study was designed as a cross-sectional survey on 700 students in secondary schools using multiple cluster sampling in Yazd, Iran in 2013. We applied 2 self reported questionnaires: DASS (depression anxiety stress scales)-42 for assessing mental disorders (anxiety, stress and depression) and a standard self-reported valid and reliable questionnaire for recording child abuse information in neglect, psychological, physical and sexual domains. The collected data was analyzed using SPSS software. P-values < 0.05 were considered as significant. Results: There was a statically significant correlation between mental disorder and child abuse score (Spearman rho: 0.2; P-value < 0.001). The highest correlations between mental disorders and child abuse were found in psychological domain, Spearman’s rho coefficients were 0.46, 0.41 and 0.36 for depression, anxiety and stress respectively (P-value < 0.001). Based on the results of logistic regression for mental disorder, females, last born adolescents and subjects with drug or alcohol abuser parents had mental disorder odds of 3, 0.4 and 1.9 times compared to others; and severe psychological abuse, being severely neglected and having sexual abuse had odds 90, 1.6 and 1.5 respectively in another model. Conclusions: Programming for mandatory reporting of child abuse by physicians and all health care givers e.g. those attending schools or health centers, in order to prevent or reduce its detrimental effects is useful and success in preventing child abuse could lead to reductions in the prevalence of mental disorders.

Sexual selection in a tropical fruit fly : role of a plant derived chemical in mate choice

The specific mechanisms by which selective pressures affect individuals are often difficult to resolve. In tephritid fruit flies, males respond strongly and positively to certain plant derived chemicals. Sexual selection by female choice has been hypothesized as the mechanism driving this behaviour in certain species, as females preferentially mate with males that have fed on these chemicals. This hypothesis is, to date, based on studies of only very few species and its generality is largely untested. We tested the hypothesis on different spatial scales (small cage and seminatural field-cage) using the monophagous fruit fly, Bactrocera cacuminata. This species is known to respond to methyl eugenol (ME), a chemical found in many plant species and one upon which previous studies have focused. Contrary to expectation, no obvious female choice was apparent in selecting ME-fed males over unfed males as measured by the number of matings achieved over time, copulation duration, or time of copulation initiation. However, the number of matings achieved by ME-fed males was significantly greater than unfed males 16 and 32 days after exposure to ME in small cages (but not in a field-cage). This delayed advantage suggests that ME may not influence the pheromone system of B. cacuminata but may have other consequences, acting on some other fitness consequence (e.g., enhancement of physiology or survival) of male exposure to these chemicals. We discuss the ecological and evolutionary implications of our findings to explore alternate hypotheses to explain the patterns of response of dacine fruit flies to specific plant-derived chemicals.