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PubMed2003

Substance use behaviors among college students with same-sex and opposite-sex experience: results from a national study.

OBJECTIVES: This study seeks to describe the population of college students with same-sex sexual experience and determine if these students report more substance use than their peers with only opposite-sex experience. METHODS: Questionnaires were completed by a national random sample of college students on 119 campuses in 1999. A total of 10,301 sexually active students were categorized as having only opposite-sex, only same-sex, or both-sex partners, and their smoking, binge drinking, and marijuana use behaviors were compared. RESULTS: Students who report same-sex sexual experiences comprise 6.1% of respondent. Women with both-sex partners were approximately twice as likely to smoke, binge drink, and use marijuana as women with only opposite-sex partners (OR=1.41-2.78), but women with only same-sex partners were not at increased risk for these behaviors. Men with both-sex partners were less likely to binge drink (OR=0.54) than men with only opposite-sex partners. CONCLUSIONS: Students with same-sex experience are present at every type of college. College women with both-sex partners appear to be an appropriate target for health interventions; outreach to these students and further study of related behaviors are warranted.

Adolescent↗
PubMed2004

A descriptive analysis of HIV risk behavior among men having sex with men attending a large sex resort.

This study assessed the prevalence of various HIV-associated risk behaviors among men who have sex with men (MSM) attending a popular sex resort in the southern United States. One hundred fifty men completed an anonymous self-administered questionnaire (91% response rate). Men currently resided in 14 states. One sixth reported being HIV-positive. During a typical resort visit, men averaged 4 sex partners. About two thirds of the men had anal sex during a typical resort stay; of these, 21% reported never using condoms and 41% reported always using condoms. HIV risk behavior over the past few months was also assessed. Men averaged 10 sex partners. Meeting partners by means of the Internet (57%) and bathhouses--excluding sex resorts--(40%) was common. Most men (62%) reported having group sex. About one half (49%) engaged in unprotected anal sex. Significant differences in recent frequency of unprotected anal sex between HIV-positive and HIV-negative men were not found (P = 0.74). Among those using condoms, 20% reported not using condoms from start to finish of sex, 7% reported breakage, and 6% reported slippage. Twenty-three percent had anal sex without lubrication. Fisting and the use of nonprescription sildenafil citrate (Viagra) was reported by about one sixth of the men. The findings suggest that MSM attending sex resorts may experience substantial risk of HIV infection. Sex resorts may be an important venue for HIV prevention.

Condoms↗
PubMed2006

Evolution of sex-biased maternal effects in birds: III. Adjustment of ovulation order can enable sex-specific allocation of hormones, carotenoids, and vitamins.

Overlap in growth of offspring should constrain the opportunity for sex-biased maternal effects, yet sex-specific allocation of maternal resources among simultaneously growing ova is often observed in vertebrates. In birds, such allocation can be accomplished either by temporal clustering of ova that become the same sex, resulting in sex-biased egg-laying order, or by follicle-specific delivery of maternal resources. Two house finch populations at the northern and southern boundaries of the species range have opposite ovulation sequences of male and female eggs, and thus, in the absence of sex differences in ova growth or sex-specific maternal strategies, would be expected to have opposite sex-specific accumulation of maternal products. We found that the populations had strong and similar gradients of steroid distribution in relation to ovulation order, whereas distribution of carotenoids and vitamins correlated with each follicle's accumulation of steroids. In both populations, temporal bias in production of sons and daughters within a clutch enabled strongly sex-specific acquisition of maternal products, and oocytes of the same sex were highly interdependent in their accumulation of steroids. Moreover, in nests where the sex-bias in relation to ovulation order deviated from population-specific patterns, eggs had highly distinct concentrations of steroids, carotenoids and vitamins. These results and previous findings of sex-specific yolk partitioning among oocytes suggest that oocytes that become males and females are temporally or spatially clustered during their ovarian growth. We discuss the implication of these findings for the evolution of sex-specific maternal resource allocation.

Animals↗
PubMed1985

Sex differences in avian embryo pulmonary surfactant production: evidence for sex chromosome involvement.

Sex differences in fetal pulmonary surfactant production have been shown in mammalian species, with the female at an advantage. A relationship between fetal sexual differentiation and the development of pulmonary surfactant production has been proposed. We hypothesized that if sex chromosomal factors play a role in causing the surfactant sex difference, then a reversal in the sex karyotype would be associated with a reversal in the surfactant sex difference and in some sex-specific responses to hormonal regulators of fetal surfactant production. To test this, we measured the surfactant-related phospholipids phosphatidylcholine and saturated phosphatidylcholine (SPC) in lung homogenates of avian embryos in which the male sex karyotype is homozygous (ZZ) and the female heterozygous (ZW). The following experimental groups were monitored: untreated controls on days 15 through 21 of gestation; embryos injected with 250 micrograms 17 beta-estradiol or of the antiestrogen CI 628; embryos injected with 250 micrograms testosterone or of the antiandrogen Flutamide; and embryos injected with 0.75 micrograms dexamethasone or 100 micrograms 11-deoxycortisol. Untreated controls exhibited significantly higher PC/milligram lung weight and SPC/milligram lung weight ratios in male embryos at gestation days 15 through 19. Hormone treatments also produced sex-specific effects. Dexamethasone significantly accelerated the male lung SPC concentration (35% over control) without affecting that of females. Glucocorticoid inhibition with 11-deoxycortisol significantly reduced the lung SPC concentration of both males and females, each by 19%. Testosterone significantly increased the female lung SPC concentration by 23%, and Flutamide significantly lowered this in the females by 24%. Estrogen reversed the sex difference by producing a relatively small (16%) decrease in the male lung SPC content while significantly increasing that of the females by 32%. CI 628 produced a modest and proportionate reduction of the lung SPC content in both sexes. These data provide evidence for a male advantage in fetal pulmonary surfactant production in the avian system, the reverse to that observed in humans, rabbits, rats, and mice. The known sex-specific responses of the developing surfactant system to glucocorticoids and to androgens are also reversed in the chick embryo as compared to the mammal. This gives additional support to the proposed link between the process of fetal sexual differentiation and the dimorphism in fetal pulmonary surfactant production and suggests that the sex chromosomes play an important regulatory role in the dimorphism of fetal surfactant production.

Animals↗
PubMed1991

[The antenatal diagnosis of the sex of the fetus by the cytological determination of sex chromatin].

Forty women between 17 and 23 weeks' gestation were included in the study, whose interruption of pregnancy was performed by medical and social indications. The method of Aburel-Atanasov was used as in 10 ml of the removed amniotic fluid sex chromatin was examined cytologically on cellular smears. Staining and determination of sex chromatin was made by the method of Dokumov. The fetus of male sex, when there was no sex chromatin, but the sex was female, when it was present in various percentage of cells. The genuine sex of the fetus was determined after interruption of pregnancy. Coincidence of cytological and genuine sex of the fetus was found in 36 cases (92.31%), but the sex was determined not exactly in 3 cases (7.69%). There was no sufficient material for preparation of high-grade cytological smears in one case. 14 out of 40 fetuses were of female sex (with sex chromatin in 28.57% of cells on the average) and 25 of male sex. The significance and advantages of the method in comparison with other methods for determination of fetal sex at the same term of pregnancy are discussed.

Amniotic Fluid↗
PubMed1998

Origin of sex for error repair. III. Selfish sex.

According to the repair hypothesis, sex originated as a cooperative interaction-the benefit being damage repair. As with all cooperative strategies, cooperative sex may be vulnerable to selfish mutants. The purpose of the present paper is to understand what implications such selfish mutants may have both for the origin of sex, especially in competition with asexual diploidy, and for the elaboration of the sexual cycle, especially in facultatively sexual organisms. Asexual diploids are assumed to effectively and instantaneously repair all damages without expression of deleterious recessive mutations. Costs to asexual diploidy are considered in terms of its birth rate and mortality rate. The main results of the present paper are as follows. (i) Asexual diploidy wins when the costs of diploidy are small, mortality rates low, and damage rates high. (ii) Beginning with an ancestral state in which cells are asexual haploids, the sexual life cycle would emerge before asexual diploidy as a response to increasing DNA damage. (iii) Selfish sex is a far more robust repair strategy than cooperative sex, especially in competition with asexual diploidy. (iv) Although cooperative sex is more adaptive in extreme environments characterized by high damage and high mortality, selfish sex can still invade in these regions and take the entire system to extinction. (v) Once it is present, selfish sex is stable to asexual diploidy over a wide range of parameter values and can persist in regions of parameter space forbidded to the asexual diploid. These results help to address a concern of the gene repair theory of sex, which is that efficient repair in an asexual diploid is a better strategy than sex. Data from microbes bearing on the results are discussed as is the relationship between facultative sex in multicellular organisms and selfish sex in microbes.

Bacterial Physiological Phenomena↗
PubMed2005

The sex difference of plasma homovanillic acid is unaffected by cross-sex hormone administration in transsexual subjects.

There is a close relationship between the brain and the endocrine system. The brain expresses receptors for sex steroids and is capable of metabolizing these hormones. We explored (1) sex differences in homovanillic acid (HVA), a metabolite of the neurotransmitter dopamine, and (2) the effects of cross-sex steroid administration in transsexual subjects. First, we compared plasma HVA levels between 38 male and 34 female healthy volunteers (not using hormone replacement therapy) of a mean age of 72 years (range 65-84 years). Secondly, we measured plasma HVA levels in 15 male-to-female transsexuals treated with 100 microg ethinyl estradiol/day and 100 mg cyproterone acetate/day for 4 months, and in 17 female-to-male transsexuals treated with testosterone esters (250 mg/2 weeks i.m. for 4 months). Plasma HVA levels were lower in elderly men than in elderly postmenopausal women (geometric mean 25.4 nmol/l (percentile (P)10 4.9; P90 69.8) vs 39.0 nmol/l (19.0; 76.1); P=0.027). In transsexuals before cross-sex hormone administration, genetic males also had lower plasma levels of HVA than genetic females (geometric mean 14.8 nmol/l (P10 7.0; P90 35.0) vs 34.3 nmol/l (21.8; 61.4); P<0.001). Cross-sex hormone administration did not affect plasma HVA in either group (P>0.5). The pretreatment sex difference in plasma HVA was unaffected after 4 months of cross-sex hormone administration (P=0.003). The sex difference in plasma HVA was not reversed by cross-sex hormone administration in transsexuals, and was also preserved in elderly subjects. This indicated that differences in dopamine gene expression were largely unaffected by exposure to sex hormone levels in adulthood, but must rather be explained by a sex difference in genetic factors or by the organizing effects of sex hormones during early development.

Aged, 80 and over↗
PubMed2001

Conflict behaviors toward same-sex and opposite-sex peers among male and female late adolescents.

Differences between males and females in regard to conflict behaviors toward same-sex and opposite-sex peers were examined in a sample of 501 undergraduate university students (326 males, 175 females). They completed a one-page questionnaire containing the theoretical definitions of five conflict behaviors identified by Thomas (1976): competing, avoiding, accommodating, compromising, and collaborating. Students were asked to rate the extent to which they exhibit each of these conflict behaviors, on a 5-point Likert-type scale, separately for same-sex and opposite-sex peers. Results revealed that males reported more competing behavior toward same-sex peers than toward opposite-sex peers, and more avoiding behavior toward opposite-sex peers than toward same-sex peers. Males, compared to females, reported more accommodating behavior toward both same-sex and opposite-sex peers. These findings support the view that preferences regarding conflict behaviors are different for males and females, particularly as exhibited toward same-sex and opposite-sex peers.

Adolescent↗
PubMed2006

Millions of missing girls: from fetal sexing to high technology sex selection in India.

The morality and acceptability of using prenatal diagnosis for sex selection is being extensively debated around the world as advances in assisted reproductive technologies (ART) and embryology have enabled selective implantation of embryos of the desired sex (George and Dahiya, 1998; Savulescu, 1999; Raphael, 2002; Harris, 2005; Robertson, 2005; Snider, 2005). Sophisticated methods of separation of semen, originally developed for cattle breeding, are being used for human sex selection. Recently, non-invasive methods of fetal sex determination in the first trimester (from 6 weeks) of pregnancy have also emerged (Hahn and Chitty, 2005). Market forces that promote sex selection along with libertarian ideologues have assisted in blurring the ethical limits (Paul, 2001; President's Council on Bioethics, 2003). The widespread misuse of sex selection for eliminating girls before birth in India and among the Indian diaspora needs to be brought into the global 'intellectual discourse'. It is imperative that Western ethicists recognize the genocidal nature of sex selection taking place in certain Asian countries. Even if they believe that these trends will not affect mainstream Western societies, the promotion or tolerance of sex selection amounts to a 'crime of silence' against this ongoing genocide in China and India. I have been concerned with issues of the girl child in India for over two decades and sex selection among Asian Indians in North America (George et al., 1992; George et al., 1993; George and Dahiya, 1998). This article examines the missing millions of girls, but will not consider the 1980s campaign against fetal sex determination, Indian feminists' recognition of sex selection as violence against women (unlike several Western feminists, Moazam, 2004), or the Government's response to regulate prenatal diagnostic techniques in 1994 (George and Dahiya, 1998; George, 2002).

Abortion, Induced↗
PubMed2000

Factors associated with condom use for oral sex among female brothel-based sex workers in Singapore.

BACKGROUND AND OBJECTIVE: The prevalence of oral sex increased from 27.1% in 1992 to 81.1% in 1997, with a concomitant increase in pharyngeal gonorrhea, among female sex workers in Singapore. The extent of condom use for oral sex among them is unknown. GOAL: To determine the prevalence of and factors associated with consistent condom use during oral sex. STUDY DESIGN: A cross-sectional study of 225 women randomly selected from the surveillance scheme register of female brothel-based sex workers with a history of oral sex documented in their medical records. RESULTS: Slightly more than half (56.9%) consistently used condoms for oral sex compared to 97% for vaginal sex. Condom use was significantly higher among middle than high class sex workers (adjusted rate ratio: 1.52, 95% CI: 1.01-2.29) and those with negotiation skills (adjusted rate ratio: 1.95, 95% CI: 1.32-2.07). CONCLUSION: Sex workers should be taught skills to negotiate condom use for oral sex.

Adult↗
PubMed2004

Field survey of sex-reversals in the medaka, Oryzias latipes: genotypic sexing of wild populations.

The medaka, Oryzias latipes, has an XX/XY sex determination mechanism. A Y-linked DM domain gene, DMY, has been isolated by positional cloning as a prime candidate for the sex-determining gene. Furthermore, the crucial role of DMY during male development was established by studying two wild-derived XY female mutants. In this study, to find new DMY and sex-determination related gene mutations, we conducted a broad survey of the genotypic sex (DMY-negative or DMY-positive) of wild fish. We examined 2274 wild-caught fish from 40 localities throughout Japan, and 730 fish from 69 wild stocks from Japan, Korea, China, and Taiwan. The phenotypic sex type agreed with the genotypic sex of most fish, while 26 DMY-positive (XY) females and 15 DMY-negative (XX) males were found from 13 and 8 localities, respectively. Sixteen XY sex-reversals from 11 localities were mated with XY males of inbred strains, and the genotypic and phenotypic sexes of the F(1) progeny were analyzed. All these XY sex-reversals produced XY females in the F(1) generation, and all F(1) XY females had the maternal Y chromosome. These results show that DMY is a common sex-determining gene in wild populations of O. latipes and that all XY sex-reversals investigated had a DMY or DMY-linked gene mutation.

Animals↗
PubMed2026

A pan-cancer single-cell atlas uncovers the role of sex hormones and chromosomes in sex-divergent reprogramming of the tumor microenvironment.

BACKGROUND: Sex bias is pervasive in tumors; however, how sex chromosomes and hormone-responsive signaling shape the tumor microenvironment (TME) remains insufficiently characterized. Considering the critical impact of the TME on tumor progression and response to immunotherapy, a pan-cancer investigation of sex-specific and cancer-context-dependent TME features is warranted. METHOD: Based on stringent inclusion criteria, we constructed a high-resolution pan-cancer single-cell sequencing atlas by integrating 31 publicly available single-cell RNA-seq datasets, comprising a total of 1,831,436 cells by integrating 468 samples from eight types of non-sex-specific solid tumors (282 males and 186 females). After correcting for batch effects, we identified major and minor cellular subsets. Multiple computational approaches were applied to investigate sex-associated differences in cellular composition, gene expression, pathway activity, malignant cell states and intercellular communication. RESULTS: We systematically compared sex-specific TME features across eight common solid malignancies. Male-biased CD8+ T cell exhaustion emerged as a recurrent but non-uniform feature, with its magnitude varying across cancer types and being modified by tissue-specific contexts. This pattern was associated with androgen-response signature scores and expression-based loss of the Y chromosome (LOY) scores. M2-like macrophage polarization showed a more cancer-type-dependent pattern; although female-biased enrichment was observed in selected malignancies, it did not represent a uniform pan-cancer feature. Expression-based X chromosome inactivation (XCI)/XCI escape-related programs, estrogen-response signature scores and stromal components, including fibroblasts and endothelial cells, were associated with macrophage and immune-regulatory states in specific tumor contexts. Tumor cells of male origin displayed higher genomic instability and more aggressive phenotypes, with androgen-response signatures and LOY contributing to the development of a male biased malignant state. Furthermore, expression-based LOY scores in malignant cells were associated with CD8+ T cell exhaustion based on transcriptomic proxies. CONCLUSION: Our study uncovers extensive but heterogeneous sex-specific differences in the TME across multiple cancer types. We propose a regulatory framework linking sex chromosomes, hormone-responsive signaling and TME interactions, which is consistent with recurrent male-biased CD8&#x207a; T cell exhaustion and context-dependent M2-like macrophage polarization. Importantly, the magnitude and, in some cancers, the direction of these sex-biased features are modified by tissue-specific contexts. These findings underscore the need to include sex chromosome and hormone status as essential biological variables in studies of the tumor microenvironment and the design of immunotherapies.

Tumor Microenvironment↗
PubMed2000

An instrument to measure safer sex strategies used by male sex workers.

Several studies have related safe sex in the commercial sex encounter to the ability of sex workers to apply specific safer sex strategies. However, no instrument has been previously available to measure these skills. The Safer-Sex Strategy Scale (SSS) was developed for such purposes. The psychometric properties (reliability and validity) were evaluated with a sample of sex workers recruited from Australian cities. A questionnaire was administered to 184 sex workers aged 18-58 years using a convenience sampling method. Results indicated that the SSS can be conceptualized as a four variation construct and can be reliably (all subscales yielded at least a Cronbach's alpha = .60) and validly measured. Additionally, the relationship of the SSS to various sex work experiences was explored. The results show that the length of time working as a sex worker and contact with sex work organizations and sexual health clinics appear to influence the level of agreement of using the safer sex strategies evaluated.

Adolescent↗
PubMed2004

Molecular sexing of prey remains permits a test of sex-biased predation in a wintering population of western sandpipers.

Population sex ratios in monogamous birds are often male biased. One factor that can affect population sex ratios is sex-biased predation. However, most estimates of sex-biased predation in birds have focused on species with obvious sexual colour dimorphism or body size dimorphism. Data on sexually monomorphic birds are generally lacking. In the present study, we adopt a PCR-based sexing procedure to help test for sex-biased predation in a wintering population of western sandpipers (Calidris mauri), a shorebird that shows only subtle sexual size dimorphism. Specifically, by comparing the a priori determined sex ratio of live birds wintering at a site in western Mexico to the molecular estimate obtained from depredated birds at this same site, we were able to perform a population-specific test for sex bias in predator-induced mortality. The proportion of females estimated from living (ca. 25%) versus dead (ca. 24%) individuals was in fact not significantly different, indicating that the strong male bias in this population is not due to differential predation. However, molecular sexing of prey remains is a hitherto unexploited test of sex-biased predation in birds, and is potentially applicable to any species for which prey remains can be gathered. We discuss our results in the context of alternate ecological hypotheses for population sex biases.

Animals↗
PubMed2002

Sex determination and sex chromosome evolution in the medaka, Oryzias latipes, and the platyfish, Xiphophorus maculatus.

The first vertebrate master sex-determining gene different from Sry has been very recently discovered in a small aquarium fish, the medaka (Oryzias latipes). In this fish, the X and Y chromosomes apparently differ only by a 250-kb Y-specific region containing dmrt1bY (also called DMY and dmrt1Y), a male-specific copy of the autosomal gene dmrt1. Dmrt1 is a putative transcription factor probably involved in testis formation in different vertebrate lineages. Dmrt1bY is the only gene having escaped the drastic process of degeneration that devastated the small Y-specific region of the medaka. Mutations leading to truncation or lower expression of dmrt1bY result in XY male-to-female sex reversal. Hence, both genetic and functional evidences converge in making dmrt1bY an outstanding candidate for the function of a master sex-determining gene in fish. Nevertheless, dmrt1bY could not be detected in certain other Oryzias species or in more divergent fishes. Phylogenetic analysis revealed that the duplication of the autosomal dmrt1 that formed dmrt1bY is young in evolutionary terms. Hence, dmrt1bY is not the universal master sex-determining gene in fish. Because the classical fish models, such as zebrafish and pufferfish, are not very adequate to study the basis of genetic sex determination, alternative models, such as the platyfish (Xiphophorus maculatus), are re-emerging. In this fish, which is a well-suited laboratory organism, gene loci involved in pigmentation, melanoma formation, and sexual maturity have been mapped close to the master sex-determining gene. Interestingly, the platyfish can harbor three different sex chromosomes (W, X, and Y) in certain natural populations. Bacterial artificial chromosome contigs covering the sex-determining region of the platyfish are already available, and the positional cloning of the master sex-determining gene(s) should provide new insights into sex determination and sex chromosome evolution in fish and other vertebrates.

Amino Acid Sequence↗
PubMedDate not supplied

Sex ratio of male sex preselected children born to couples with exclusively female offspring.

The present study was undertaken to determine if couples with exclusively female children had a decreased probability of a male child after using male sex preselection. Selection criteria for subjects necessitated that couples have had only female children previously and had produced a child at one of 14 centers after using protocol 3 (n = 70) and modified 3 (n = 28) male sex preselection. Prior to sex selection, protocol 3 couples produced a combined total of 135 female children for an average of 2.01 (range 1-4) females per couple; modified 3 couples produced a combined total of 62 female children for an average of 2.21 (range 1-4) females per couple. The normal approximation to the binomial distribution was used to determine significant differences between the sex ratios prior to and after male sex preselection. For couples using protocol 3 there were significant differences in the sex ratio prior to sex preselection (0%) and after sex preselection (73.0%) (p less than .00003). There were also significant differences between the sex ratio prior to modified 3 (0%) and after sex preselection (86%) (p less than .00003). Couples using male sex preselection do not have a decreased probability of a male child if they have had exclusively female children.

Female↗