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PubMed2000

Growth hormone and thyroid stimulating hormone concentrations in captive male orangutans: implications for understanding developmental arrest.

There are two morphs of reproductive male in orangutans. Both morphs span the age range from adolescent to adult, but "subadult" males are smaller in size and lack secondary sexual features. In this study, urine samples were collected over a 2 year period from 23 captive male orangutans in order to define the endocrinology of this apparent arrest of secondary sexual development. Three males were juveniles, 3 to 5 years of age; seven males showed no secondary sexual trait development and were over 7 years of age; six males were in the process of developing secondary sexual features, with the youngest male being 6 years of age; and seven males were fully mature adults. Morning samples were analyzed by radioimmunoassay for levels of growth hormone (GH) and thyroid-stimulating hormone (TSH) and group hormone profiles were compared by analysis of variance. GH is the primary hormone of growth and development and its increase in teenage boys is associated with the adolescent growth spurt. TSH stimulates the thyroid to produce and secrete hormones that have metabolic effects and required for normal growth and development. Results show that arrested adolescent male orangutans have a GH level about 1/3 that of developing adolescents (P = .0006). TSH levels do not differ significantly between arrested and developing adolescents. These data complement other endocrine data showing significantly lower levels of sex steroids and luteinizing hormone (LH) in arrested males than developing males [Maggioncalda, 1995a,b; Maggioncalda et al., 1999]. Together with documented behavioral differences between reproductive males with and without secondary sexual features, these endocrine data support the hypothesis that in male orangutans there are alternative developmental pathways and corresponding alternative reproductive strategies.

Age Factors↗
PubMed1994

Gender differences in vertebral body sizes in children and adolescents.

PURPOSE: To determine whether differences in vertebral bone densities or sizes account for gender differences in skeletal mass during growth. MATERIALS AND METHODS: Quantitative computed tomography (CT) was used to measure the densities of cortical and cancellous bone and dimensions of the lumbar vertebral bodies in 196 healthy children and adolescents, ages 4-20 years. RESULTS: Neither cancellous nor cortical bone densities differed between boys and girls with age or level of sexual development. In contrast, the cross-sectional areas of the vertebral bodies were greater in boys than girls throughout childhood and adolescence. Even when prepubertal children were matched for chronologic age, bone age, height, and weight, the size of the vertebral bodies was 17% greater in boys. This disparity in vertebral body size increased with level of sexual development and was greatest at sexual maturity. CONCLUSION: Lower vertebral bone mass of women as compared with men may result from early gender differences in the sizes of bones rather than differences in bone densities.

Adolescent↗
PubMed1976

Plasma prolactin levels in maturing intact and cryptorchid male rats: development of stress response.

In order to determine the possible role of the seminiferous tubules in the regulation of prolactin secretion during sexual development, male rats were rendered cryptorchid at 22 days of age, and thereafter different groups of animals were decapitated at 8-10 day intervals between Day 32 and Day 70. Cryptorchid rats showed destruction of the germinal epithelium accompanied by increased plasma FSH and, to a much lesser extent, increased plasma LH titers. Nevertheless, plasma prolactin levels were similar to those of intact controls throughout the entire period studied. Plasma prolactin titers in intact controls remained uniformly low from Day 20 to Day 70, contrasting with previous reports in which increasing prolactin levels have been observed during sexual development. To determine the reason for this apparent discrepancy, a longitudinal experiment was conducted in which intact and cryptorchid male rats were bled every 10 days from Day 30 to Day 70, following a 3-min period of exposure to ether fumes. The prolactin response to this stress increased markedly with age. A similar pattern of prolactin was observed in a cross-sectional study in which different groups of intact animals were bled following a 3-min period of ether exposure, at ages ranging from 20 to 70 daysmthe results indicate that unlike FSH secretion, prolactin secretion is not controlled by the seminiferous tubules. In addition, they suggest that the pattern of increasing plasma prolactin previously described in the developing male rat is at least in part caused by an age-dependent increase in responsiveness of prolactin to stress.

Age Factors↗
PubMed2005

Differential expression of the chsE gene encoding a chitin synthase of Aspergillus nidulans in response to developmental status and growth conditions.

Expression of chsE encoding one of the five chitin synthases of Aspergillus nidulans was analyzed. Expression of chsE was moderate in conidiophores, but somewhat weaker in vegetative mycelia. During sexual development, chsE was expressed strongly in young cleistothecia and hülle cells, but little in mature sexual structures. Deletion of chsE caused a significant decrease in the chitin content of the cell wall during early sexual development. Expression of chsE was increased by substituting glucose with lactose or by addition of 0.6M KCl or NaCl, but affected little by substituting glucose with sodium acetate. Consequently, chsE was shown to have a mode of expression distinct from those of the other chitin synthase genes, chsA, chsB and chsC.

Aspergillus nidulans↗
PubMed2001

Sexual diploids of Aspergillus nidulans do not form by random fusion of nuclei in the heterokaryon.

The sexual stage of Aspergillus (Emericella) nidulans consists of cleistothecia containing asci, each with eight ascospores. The fungus completes the sexual cycle in a homokaryotic or a heterokaryotic mycelium, respectively. The common assumption for the last 50 years was that different nuclear types are not distinguishable when sexual development is initiated. When cultured on a medium limited for glucose supplemented with 2% sorbitol, sexual development of A. nidulans is slowed and intact tetrads can be isolated. Through tetrad analysis we found that unlike haploid nuclei fuse preferentially to the prezygotic diploid nucleus. When heterokaryons are formed between nuclei of different genetic backgrounds, then recombinant asci derived from opposite nuclei are formed exclusively. Strains in the same heterokaryon compatibility group with moderate differences in their genetic backgrounds can discriminate between the nuclei of a heterokaryon and preferentially form a hybrid diploid nucleus, resulting in 85% recombinant tetrads. A. nidulans strains that differ at only a single genetic marker fuse the haploid nuclei at random for formation of diploid nuclei during meiosis. These results argue for a genetically determined "relative heterothallism" of nuclear recognition within a heterokaryon and a specific recruitment of different nuclei for karyogamy when available.

Aspergillus nidulans↗
PubMed1999

Sexual behaviors in autism: problems of definition and management.

Surveys of sexual behavior in autism suggest a variety of behavioral expression. However, the course of sexual development in autism is unplotted, leaving questions about the normalcy of specific behaviors. Even less is known about deviations of sexual development and the incidence of paraphilias in this population. We explore the problems of definition of sexual behaviors and describe a case report that highlights the difficulties of management. An application of a testosterone-suppressing medication and its effect on sexual behavior are reported. After failure of behavioral and educational programs, leuprolide, an injectable antiandrogen, resulted in suppression of behaviors and retention of the participants' community placement. Follow-up for almost 3 years shows no abnormal physical effects. Dosage has been tapered over that period to a low but effective dose. Directions for research are discussed.

Adolescent↗
PubMed1996

Mating systems in ascomycetes: a romp in the sac.

The ascomycetous fungi choose between sexual and asexual reproduction; it is only when appropriately stressed that most resort to sexual development. Many of the proteins known to regulate development in animals (homeodomain proteins, HMG-box proteins) are also central to the control of sexual differentiation in the ascomycetes. Most ascomycete mating-type loci are structurally complex idiomorphs (large regions of nonhomologous DNA), in that they encode multiple products of probable independent evolutionary origin. The products of the mating-type genes are the master regulators of sexual development; we are just beginning our search for factors involved in the signal transduction pathway downstream from these master regulators.

Ascomycota↗
PubMed2000

Development and sexual maturation of Echinococcus vogeli in an alternative definitive host, Mongolian gerbil (Meriones unguiculatus).

An alternative definitive host model for Echinococcus vogeli was developed using Mongolian gerbils. The animals treated with prednisolone tert-butylacetate were orally inoculated with protoscoleces of E. vogeli and the development of worms in the small intestine was observed until 50 days post infection (DPI). The parasites were recovered most frequently from the anterior part of the small intestine. The band formation (the sign of proglottisation) of the worm was observed at 7 DPI, the second proglottid and tests formation at 14 DPI, spermatozoa in seminal receptacle and cleavage of ova in uterus at 21 DPI, the hook formation of oncospheres at 28 DPI and the embryophore formation at 34 DPI. Eggs in the feces were first detected at 35 DPI. The coproantigen detection method developed for E. multilocularis could detect the E. vogeli coproantigen early in the infection, at 7 DPI during the prepatent period. Therefore, this technique could be used for the diagnosis of E. vogeli, replacing ordinary fecal egg examination.

Animals↗
PubMed2002

Clinical trial development in female sexual dysfunction.

The development of clinical trial protocols for testing safety and efficacy of therapeutic interventions requires the blending of traditional methodologies with special consideration of the indications. The specificity of disease definition, precise identification of target populations, study design rationales, instruments, and selection of endpoints all contribute to the difficulty of conducting successful trials in this arena. An understanding of these issues can lead to improved clinical protocols.

Clinical Trials as Topic↗
PubMed1989

Blockade of neonatal activation of the pituitary-testicular axis: effect on peripubertal luteinizing hormone and testosterone secretion and on testicular development in male monkeys.

The objective of this study was to examine the effect of blockade of neonatal activation of the pituitary-testicular axis, using a GnRH agonist, on sexual development in male rhesus monkeys. Monkeys were treated with either a GnRH agonist (10 micrograms/day; n = 8) or vehicle (n = 9) for 112 days using osmotic minipumps beginning at 10-13 days of age. In control monkeys serum LH and testosterone concentrations during the first 3 postnatal months were similar to those in adults; they then declined to very low levels. GnRH agonist administration caused an immediate and precipitous decline in serum LH and testosterone concentrations to very low levels, and both remained low throughout the rest of the agonist administration period. Neither group had any significant elevation in serum LH or testosterone concentrations during the next 2 yr. In the control monkeys serum LH and testosterone began to rise during the third year, with a rapid increase occurring during the fall coincident with the breeding season. This peripubertal rise of LH and testosterone secretion was associated with rapid enlargement of the testes and the appearance of sperm in ejaculates. The monkeys who had received GnRH agonist had subnormal serum LH and testosterone increases, and testicular enlargement was also attenuated compared to that in the control animals during the third year of life. Semen samples were recovered from only 50% of the GnRH agonist-treated monkeys during this period, and the sperm count per ejaculate was suppressed. The serum LH responses of the GnRH agonist-treated monkeys to an iv bolus dose of GnRH (5 micrograms/kg BW) during the third year were normal. These results suggest that the induction of reversible hypogonadotropin-hypogonadism in neonatal male monkeys alters subsequent testicular development and peripubertal endocrine changes. Thus, neonatal activation of the pituitary-testicular axis may be a critical developmental event in the process of sexual development in male primates.

Animals↗
PubMed2006

Sexual identity development among gay, lesbian, and bisexual youths: consistency and change over time.

A longitudinal report of 156 gay, lesbian, and bisexual youths examined changes in sexual identity over time. Fifty-seven percent of the youths remained consistently self-identified as gay/lesbian, 18% transited from bisexual to gay/lesbian, and 15% consistently identified as bisexual over time. Although youths who consistently identified as gay/lesbian did not differ from other youths on time since experiencing sexual developmental milestones, they reported current sexual orientation and sexual behaviors that were more same-sex centered and they scored higher on aspects of the identity integration process (e.g., more certain, comfortable, and accepting of their same-sex sexuality, more involved in gay-related social activities, more possessing of positive attitudes toward homosexuality, and more comfortable with others knowing about their sexuality) than youths who transited to a gay/lesbian identity and youths who consistently identified as bisexual. Contrary to the hypothesis that females are more sexually fluid than males, female youths were less likely to change identities than male youths. The finding that youths who transited to a gay/lesbian identity differed from consistently gay/lesbian youths suggests that identity integration continues after the adoption of a gay/lesbian sexual identity.

Adolescent↗
PubMedDate not supplied

[Puberal development in Cuban adolescents].

Within the sample of the National Investigation of Development and Growth in Cuba in 1972, the mean age of menarche in girls and the different stages of sexual development in both sexes were analyzed. For menarche, the status method was employed with logit analysis in a national aleatory sample that comprised 13,143 girls. The mean age for menarche was 13.01 +/- 0.02 years with a value of 12.77 for urban population and 13.26 for the rural. The study was also made by provinces. The sexual development, according with the stages of Tanner's method was investigated. The sample included about 26,000 individuals from 8 to 18 years old. The results obtained for the different percentiles with the logit analysis are offered. The importance that adolescents have a different maturation rhythm; precocious, average and late, becomes evident and the importance of the knowledge of these variants in normal individuals by the personnel in charge is pointed out.

Adolescent↗
PubMed1993

Social contagion and adolescent sexual behavior: a developmental EMOSA model.

Epidemic Models of the Onset of Social Activities (EMOSA models) describe the spread of adolescent transition behaviors (e.g., sexuality, smoking, and drinking) through an interacting adolescent network. A theory of social contagion is defined to explain how social influence affects sexual development. Contacts within a network can, with some transition rate or probability, result in an increase in level of sexual experience. Five stages of sexual development are posited. One submodel proposes a systematic progression through these stages; a competing submodel treats each as an independent process. These models are represented in sets of dynamically interacting recursive equations, which are fit to empirical prevalence data to estimate parameters. Model adjustments are substantively interpretable and can be used to test for and better understand social interaction processes that affect adolescent sexual behavior.

Adolescent↗
PubMed2003

Sexually dichromatic protogynous angelfish Centropyge ferrugata (Pomacanthidae) males can change back to females.

Protogynous hermaphroditism, female-to-male sex change, is well known among reef fishes where large males monopolize harems of females. When the dominant male disappears from a harem, the largest female may change sex within a few weeks. Recently, from experiments with some protogynous haremic fishes in which two males' cohabitated, it was confirmed that sexual behavior and gonads were completely reversible according to individual social status. However, the ability to reverse secondary-developed sexual body coloration has never been examined in any protogynous fish. We conducted two male cohabitation experiments with the protogynous haremic angelfish, Centropyge ferrugata, which has conspicuous sexual dichromatism on the dorsal fin. Smaller males of C. ferrugata soon performed female-specific mating behaviors when they became subordinated after losing a contest. They then completed gonadal sex change to females 47 or 89 d (n=2) after beginning cohabitation. In the course of the reversed gonadal sex change, male-specific coloration on the dorsal fin changed to that of a female. Thus, the sex of C. ferrugata, including secondary developed sexually dichromatic characteristics, can be completely reversible in accord with their social status.

Adaptation, Physiological↗