The contribution of adrenal and gonadal androgens to the growth in height of adolescent males

Gonadal androgens are known to regulate the rate of growth in height during adolescence, particularly in males, but little is known of the role of adrenal androgens in this process. In a prospective multiple regression model we show that both adrenal and gonadal androgens contribute to the increasing rate of growth in height prior to peak height velocity and the decreasing rate of height growth in later adolescence. Since adrenal androgen secretion begins in mid-childhood, long before gonadal maturation and the secretion of testicular androgens, these findings may prove helpful in explaining population variation in adolescent growth.     

A Comparison of Health Complaints of Settled and Nomadic Turkana Men

This article examines the health complaints of settled and nomadic Ngisonyoka Turkana of northwest Kenya. Samples of 152 nomadic and 124 settled men, aged 14 and over, were surveyed about their health status. The general pattern of disease reported concurs with previous studies of health among Turkana; that is, the primary complaints are respiratory tract infections and eye infections. The settled Turkana reported more severe complaints and higher rates of infectious disease than the nomads, including a significantly higher frequency of cold with cough, eye infection, and chest infection. Although the settled males as a group had slightly higher body mass index and other measures of body fat than the nomadic group, none of these indicators of body composition were predictive of health complaints. Observed differences in health patterns are possibly related to differences in dietary composition, exposure to pathogens associated with population density and environmental pollution, physical activity patterns, and psychosocial stress.     

Growth of nomadic and settled Turkana infants of northwest Kenya

Turkana tribespeople reside in a semi-arid savanna ecosystem in northwest Kenya. For over a decade, Ngisonyoka Turkana nomads have been studied within a multidisciplinary framework that embraces ecology, anthropology, and human population biology. Original research objectives of the South Turkana Ecosystem Project were to study nomads longitudinally and within the context of the dry savanna ecosystem. These objectives have been expanded to incorporate settled Turkana who were nomads in the recent past, but who, for a variety of reasons, have taken up a life of sedentary cultivation. The research described here focused on comparisons of growth patterns of nomadic and settled infants from birth to 24 months of age. Infants were measured (recumbent length, weight, head circumference, arm and calf circumference, and selected skinfolds) in 1989 and 1990. Settled infants were slightly longer, but nomadic infants were heavier and fatter. Head circumferences were the same. Some variation was observed by season and year of measurement (from comparative surveys). Both groups showed pronounced weight faltering after 6 months of age when compared with U. S. NCHS reference values. Head circumference faltering was moderate and recumbent length faltering was only slight after 12 months of age. Comparisons of Turkana infant growth in the two populations can contribute indirectly to a better understanding of infant nutritional status, probable morbidity, and other factors, some of which may be linked to female reproduction. © 1993 Wiley-Liss, Inc.     

Age-related patterns of urinary gonadotropins (FSH and LH) and E-3-G as measures of reproductive function among Turkana males of northern Kenya

To determine age-related patterns of gonadotropins and their relationship to energetic status in a subsistence population we analyzed urinary FSH, LH, and estrone-3-glucuronide (E-3-G) along with anthropometric measures among Turkana males of northern Kenya. Subjects were 134 nomadic and 109 settled males ages 20 to 80+. FSH, LH and E-3-G were significantly higher among the settled, compared to nomadic, males. LH, but not FSH, showed a significant increase across 10 year age groups among all the men. E-3-G increased across age groups only among the settled males. Controlled for age, FSH was inversely related to measures of fat free and body mass among the settled men. These findings suggest an unusual age profile of gonadotropins and estrogen metabolites that may reflect the impact of fluctuating food availability. More research is needed to address the impact of energetic and social factors on the male reproductive axis among energetically stressed populations.     

Early anthropometric indices predict short stature and overweight status in a cohort of Peruvians in early adolescence

While childhood malnutrition is associated with increased morbidity and mortality, less well understood is how early childhood growth influences height and body composition later in life. We revisited 152 Peruvian children who participated in a birth cohort study between 1995 and 1998, and obtained anthropometric and bioimpedance measurements 11-14 years later. We used multivariable regression models to study the effects of childhood anthropometric indices on height and body composition in early adolescence. Each standard deviation decrease in length-for-age at birth was associated with a decrease in adolescent height-for-age of 0.7 SD in both boys and girls (all P < 0.001) and 9.7 greater odds of stunting (95% CI 3.3-28.6). Each SD decrease in length-for-age in the first 30 months of life was associated with a decrease in adolescent height-for-age of 0.4 in boys and 0.6 standard deviation in girls (all P < 0.001) and with 5.8 greater odds of stunting (95% CI 2.6-13.5). The effect of weight gain during early childhood on weight in early adolescence was more complex to understand. Weight-for-length at birth and rate of change in weight-for-length in early childhood were positively associated with age- and sex-adjusted body mass index and a greater risk of being overweight in early adolescence. Linear growth retardation in early childhood is a strong determinant of adolescent stature, indicating that, in developing countries, growth failure in height during early childhood persists through early adolescence. Interventions addressing linear growth retardation in childhood are likely to improve adolescent stature and related-health outcomes in adulthood.     

Longitudinal analysis of length growth in the chimpanzee (Pan troglodytes)

The adolescent growth spurt in linear dimension in humans is considered to be unique among mammals, but few comparative studies have been done, even on chimpanzees. Growth of the summed length of crown to rump, thigh, and leg was studied longitudinally in 12 chimpanzees. We took body weight growth and reproductive maturation into consideration. Reproductive maturation was monitored by the swelling of sexual skin and menarche in females, and by testicular development in males. We applied two relationships found in humans between body length growth and the environment to the chimpanzees. The first relationship was the robustness of the growth spurt, meaning that the spurt is absent only in individuals under the most severe environmental pressure. Subjects maturing in a favorable or even mediocre environment are anticipated to show the growth spurt. The second relationship was catch-up growth, where, when the environment is ameliorated, growth may be accelerated to attain the target size. Catch-up growth at the end of the juvenile period may mimic the adolescent growth spurt. Results showed that subjects living under favorable conditions did not exhibit a growth spurt, and that it was only the subjects who had delayed growth in the juvenile period that showed a spurt in adolescence, the period when reproductive maturation occurred. Although we have concluded that chimpanzees do not have an adolescent growth spurt, except in cases of catch-up growth, this does not mean that they have a different growth pattern from that of humans. The absence of a growth spurt may be associated with adaptations to chimpanzee patrilineal society, where adolescent males are incorporated into the adult hierarchy at a low rank.     

The growth pattern of chimpanzees: Somatic growth and reproductive maturation inPan troglodytes

Growth of chimpanzees reared at the Kumamoto Primates Park of Sanwa Kagaku Kenkyusho Co. Ltd. was studied cross-sectionally from the viewpoints of somatic growth and reproductive maturation. Distance and velocity curves were expressed using spline function method. Males showed adolescent growth acceleration in body weight, with a peak at 7.86 yrs of age, but not in trunk length. Females showed continuous rapid growth from mid-juvenile to adolescent phase in both body weight and trunk length, but no isolated adolescent spurt. The Sanwa chimpanzees matured at about 12.5 yrs of age for females and 15.0 yrs for males. The mean adult weights and trunk lengths were 53.2 kg and 507.8 mm for males and 42.7 kg and 481.6 mm for females. The Sanwa chimpanzees had similar growth patterns to those of the Yerkes chimpanzees, although they showed a slight delay in infancy, and a higher growth rate from the early juvenile phase onwards. Growth patterns in these two laboratories may be regarded as “normative” for laboratory-reared chimpanzees. They matured earlier than wild chimpanzees by more than two years. The major reason for the retarded maturation in wild chimpanzees is the delay of growth from infant to the early juvenile phases (0–4 yrs of age), probably owing to a limited nutritional supply from the mother. Development of the testes comprised three phases: slow growth from infant to juvenile (until 6.4 yrs); rapid growth around adolescence (until 9.2 yrs); and adult (mean testicular volume, 187 cm³). Setting the nutritional standard at 2,000–2,600 Cal/day (= Kcal/day) per adult, calories were considered for captive chimpanzees in each age class.     

Testicular hormone exposure during adolescence organizes flank-marking behavior and vasopressin receptor binding in the lateral septum

Adolescence is a period during which many social behaviors emerge. One such behavior, flank marking, is a testosterone-modulated scent marking behavior that communicates dominance status between adult male Syrian hamsters. Testosterone modulates flank-marking behavior by altering neural transmission of vasopressin within a forebrain circuit. This study tested whether testicular hormones secreted during adolescence play purely a transient activational role in the display of flank-marking behavior, or whether adolescent steroid hormone secretions also cause long-term organizational changes in vasopressin binding within brain regions underlying flank-marking behavior. We tested this hypothesis by manipulating whether testicular secretions were present during adolescent development and then tested for flank-marking behavior and vasopressin receptor binding within the flank-marking neural circuit in young adulthood. Specifically, males were gonadectomized immediately before or after adolescence, replaced with testosterone 6 weeks following gonadectomy in young adulthood, and behavior tested 1 week later. Adult testosterone treatment activated flank-marking behavior only in males that were exposed to testicular hormones during adolescence. In addition, males exposed to testicular hormones during adolescence exhibited significantly less vasopressin receptor binding within the lateral septum than males deprived of adolescent hormones, suggesting that hormone-dependent remodeling of synapses normally occurs in the lateral septum during adolescence. These data highlight the importance of gonadal steroid hormone exposure during adolescence for the organization of neural circuits and social behavior.     

Differential mortality in Turkana agriculturalists and pastoralists

Nomadic pastoral populations appear to have much lower rates of growth than the otherwise very high growth rates now characteristic of populations in developing nations. Because dramatic declines in infant mortality have been a primary contributor to increased population growth rates in these countries, it has been assumed that nomadic pastoral populations are still characterized by high levels of mortality in the first few years of life. Few studies, however, have been undertaken to estimate demographic parameters for nomadic pastoral populations, and even fewer of a comparative nature have been undertaken to document the impact of subsistence strategy on demographic processes. This study compares indirect childhood mortality estimates for Turkana nomadic pastoralists with childhood mortality in a settled agricultural group within the same population and finds that pastoralists have substantially higher levels of mortality. Based on the childhood mortality estimates, model life tables are selected for pastoral and agricultural groups from which values for mean life expectancy and infant mortality are estimated and compared. Recent improvements in primary health care for the settled agricultural group are ruled out as being an important cause of their lower mortality levels, and some aspects of life-style associated with subsistence strategy are discussed as likely determinants of the mortality differences.     

Testicular and blood steroid levels in aged men

In this study, we have evaluated the hypophyso-gonadal axis in three groups of men aged 60-69, 70-79 and 80-91 years by measuring the intratesticular concentrations of several steroids (pregnenolone, progesterone, DHEA, DHEA-S, testosterone, estradiol) and serum levels of FSH, LH, testosterone, estradiol and sex hormone binding globulin (SHBG). The histological examination of testes revealed normal spermatogenesis in all examined samples. No significant changes in serum hormone and SHBG concentrations as well as in testicular steroid contents among the three groups of patients were found. However, the mean serum SHBG level was three times higher in the oldest men than in other groups and a positive correlation between patient's age and serum SHBG was observed. Therefore, the bioavailability of estradiol in the oldest men was likely diminished. Consequently, the hormonal status in aged men is rather unchanged but great variations observed between patients imply special cautious when the SHBG and estradiol levels are concerned.     

Adolescents and androgens, receptors and rewards

Adolescence is associated with increases in pleasure-seeking behaviors, which, in turn, are shaped by the pubertal activation of the hypothalamo-pituitary-gonadal axis. In animal models of naturally rewarding behaviors, such as sex, testicular androgens contribute to the development and expression of the behavior in males. To effect behavioral maturation, the brain undergoes significant remodeling during adolescence, and many of the changes are likewise sensitive to androgens, presumably acting through androgen receptors (AR). Given the delicate interaction of gonadal hormones and brain development, it is no surprise that disruption of hormone levels during this sensitive period significantly alters adolescent and adult behaviors. In male hamsters, exposure to testosterone during adolescence is required for normal expression of adult sexual behavior. Males deprived of androgens during puberty display sustained deficits in mating. Conversely, androgens alone are not sufficient to induce mating in prepubertal males, even though brain AR are present before puberty. In this context, wide-spread use of anabolic-androgenic steroids (AAS) during adolescence is a significant concern. AAS abuse has the potential to alter both the timing and the levels of androgens in adolescent males. In hamsters, adolescent AAS exposure increases aggression, and causes lasting changes in neurotransmitter systems. In addition, AAS are themselves reinforcing, as demonstrated by self-administration of testosterone and other AAS. However, recent evidence suggests that the reinforcing effects of androgens may not require classical AR. Therefore, further examination of interactions between androgens and rewarding behaviors in the adolescent brain is required for a better understanding of AAS abuse.     

Increase in plasma 5 alpha-androstane-3 alpha,17 beta-diol glucuronide as a marker of peripheral androgen action in hirsutism: a side-effect induced by cyclosporine A

Dose-dependent hypertrichosis is a common dermatological side-effect affecting the majority of patients treated with cyclosporine A (CSA). Previous studies have not demonstrated the influence of CSA on specific sex hormone levels. The aim of this study is to investigate whether CSA increases the activity of 5 alpha-reductase, an enzyme which transforms androgens into dihydrotestosterone in peripheral tissues. The metabolite which best reflects this activity is 5 alpha-androstane-3 alpha,17 beta-diol glucuronide (Adiol G). The study was carried out on 49 insulin-dependent diabetes patients participating in the double-blind "Cyclosporine-Diabète-France" clinical trial, of which 28 were treated with CSA (16 males and 12 females), and 21 received only placebo (10 males and 11 females). All patients underwent extensive clinical and laboratory evaluations prior to and during the present study. In addition to Adiol G, testosterone (T), dehydroepiandrosterone sulfate (DHEA S) and sex hormone-binding globulin (SHBG) were assayed. Levels of Adiol G increased significantly in CSA-treated groups: males, 11.86 +/- 2.58 vs 7.83 +/- 2.30 nmol/l; females, 4.48 +/- 2.70 vs 2.10 +/- 1.22 nmol/l; P less than 0.02 (comparison of means). There were no significant differences in this parameter before and during treatment in either the male or female placebo groups (paired t-test). During the treatment period, T, DHEA S, SHBG and the T/SHBG ratio did not significantly change with respect to their baseline values in any of the groups studied (comparison of means). Comparison (using paired t-test) showed a significant increase of DHEA S in CSA-treated groups: males, delta = 3.08 +/- 3.33 nmol/l, P less than 0.01; females, delta = 0.98 +/- 1.13 nmol/l, P less than 0.05. In conclusion, it is possible that CSA induces hypertrichosis or hirsutism by increasing 5 alpha-reductase activity in peripheral tissues. Nevertheless the role of increased DHEA S as a possible Adiol G precursor cannot be excluded.     

Neonatal and pubertal development in males of a cooperatively breeding primate, the cotton-top tamarin (Saguinus oedipus oedipus).

In cooperatively breeding groups of mammals, reproduction is usually restricted to a small number of individuals within the social group. Sexual development of mammals can be affected by social environment, but we know little regarding effects of the cooperative-breeding system on males. Cotton-top tamarin (Saguinus oedipus oedipus) offspring typically do not reproduce in their natal group, even though they may be physically mature. We examined neonatal and pubertal development in captive male cotton-top tamarins as an example of reproductive development within a cooperative-breeding system and to compare cotton-top tamarins with the general primate model. Puberty was characterized using both hormonal and physical measures. Data were collected on urinary levels of LH, testosterone (T), dihydrotestosterone (DHT), cortisol, and the ratio of DHT to T; testicular development; body weight; and breeding age. We determined that 1) pubertal LH secretion began at Week 37, 2) a surge of T secretion followed at Weeks 41-44, and 3) an increase in the metabolism of T to DHT may have occurred at an average age of 48.6 wk. Most of the rapid weight gain was completed by Week 24, before hormonal increases and rapid scrotal growth. We concluded that rapid pubertal testicular growth in captive cotton-top males was completed by an average 76 wk, but that completion of the individual pubertal spurt can occur between 56 and 122 wk. In a cooperative-breeding system, the opportunity for successful reproduction is dictated by the social environment, but we found no evidence that male offspring were developmentally suppressed in their natal social groups. Our findings suggest that puberty in male New World callitrichid primates occurs more quickly than puberty in Old World primates, even though both have similar patterns of development.     

Femur/stature ratio and estimates of stature in children.

The present study examines the relationship between femur length and stature in children between the ages of 8 and 18 years. In previous investigations, my colleagues and I reported the surprising finding that femur length bears a nearly constant relationship to stature in adult humans regardless of ethnicity or gender. This earlier study revealed that the femur/stature ratio averages 26.74% in adult humans, and that using the ratio to predict stature from femur length yields remarkably accurate estimates. The current study shows that femur/stature ratios of children between the ages of 8 and 11 differ significantly from their older counterparts. Between the ages of 12 and 18, there are no significant differences due to age in the femur/stature ratio; however, there are significant differences in this age group attributable to gender. This study also shows that the worldwide average adult femur/stature ratio does not adequately describe children in this age range. This study strongly documents the adolescent growth spurt in the femur/stature ratios of both males and females at the precise time one would expect to see the spurt occur (10-12 in females; 12-14 in males). This growth follows a nearly identical trajectory in both genders, with relative femur growth dominating before the peak years of the growth spurt, and relative stature growth dominating afterward. This accounts for the ratio's rise to maximum values just before peak growth, and its decline toward the adult ratio thereafter. These findings require us to use separate adolescent femur/stature ratios of 27.16 (females) and 27.44 (males) to estimate the stature of children between the ages of 12 and 18. Preliminary testing shows these ratios to be more accurate in estimating stature than the properly selected Trotter and Gleser adult regression equation. Use of the adolescent male ratio with the Homo erectus juvenile WT 15000 results in a lower stature estimate (157.4 cm) than previously reported. It is suggested that continued testing of the ratio occur, but that the values herein derived may be useful in routine forensic cases involving children in this age range, and with subadult paleontological specimens.     

Cross-sectional growth of pastoralist Karimojong and Turkana children

In this study, we compare cross-sectional growth in two Nilotic pastoralist populations, the Turkana and Karimojong of northern East Africa. Until the middle of the 18th century, these two groups constituted one population, and their genetic affinities consequently are assumed to be strong. Known differences in their subsistence practices as well as their recent cultural history allow us to consider the genetic vs. environmental determinants of their growth patterns. Growth in stature of the two groups is remarkably similar, whereas the pattern of ponderal growth varies, particularly in infancy and adolescence. Both groups demonstrate the linear adult physique that is characteristic of savanna-dwelling peoples in East Africa, but the Karimojong are heavier and fatter after early childhood. Linearity of physique is related to narrow skeletal breadth, a trait that emerges early in childhood among the Karimojong and is strongly correlated with weight: this finding supports the climatic hypothesis of human body shape and size. Extreme leanness, determined from body mass index, is correlated with fat stores, which are only weakly correlated with weight, height, or skeletal breadth. Linearity of physique appears to have a substantial genetic component, whereas fatness is hypothesized to relate to differences in subsistence strategies and exposure to environmental and cultural stress.     

Comparison of final height in monozygotic twins,one with idiopathic and isolated growth hormone deficiency treated with low dose of growth hormone

OBJECTIVE: We report final heights in a pair of monozygotic twins, one unaffected and the other affected with idiopathic and isolated growth hormone (GH) deficiency treated with human GH, and discuss the effect of GH dosage on the attainment of the genetic height potential in GH deficiency. PATIENTS: Male monozygotic twins were born at 35 weeks of gestation; birth weights were 1,876 g in the unaffected and 1,510 g in the affected twin. At 4.9 years of age, the affected twin was studied for short stature (-3.38 SD) and was diagnosed as having idiopathic and isolated GH deficiency, whereas the unaffected twin was normal in height (+/- 0 SD). GH treatment was started at the age of 5.7 years and continued throughout childhood and adolescence. The average dose of GH administered during the treatment period was 0.35 IU (0.12 mg)/kg/week. The affected twin appeared to grow normally without other hormone replacement and achieved a final height of 165.6 cm (-0.86 SD) compared with that of 166.4 cm (-0.71 SD) in the unaffected twin at 17.5 years of age. CONCLUSION: Our results indicate that a relatively low dose of GH treatment started at an early age may preserve genetic height potential in patients with isolated GH deficiency.     

Impact of socio-emotional context,brain development,and pubertal maturation on adolescent risk-taking

While there is little doubt that risk-taking is generally more prevalent during adolescence than before or after, the underlying causes of this pattern of age differences have long been investigated and debated. One longstanding popular notion is the belief that risky and reckless behavior in adolescence is tied to the hormonal changes of puberty. However, the interactions between pubertal maturation and adolescent decision making remain largely understudied. In the current review, we discuss changes in decision making during adolescence, focusing on the asynchronous development of the affective, reward-focused processing system and the deliberative, reasoned processing system. As discussed, differential maturation in the structure and function of brain systems associated with these systems leaves adolescents particularly vulnerable to socio-emotional influences and risk-taking behaviors. We argue that this asynchrony may be partially linked to pubertal influences on development and specifically on the maturation of the affective, reward-focused processing system.     

Adrenal androgens in children with short stature

Recent data suggest that adolescent individuals with growth hormone (GH) deficiency have subnormal levels of adrenal androgens (AA). In order to determine the developmental pattern of AA in GH deficiency and to assess whether AA levels can help identify children with GH deficiency, we measured plasma concentrations of dehydroepiandrosterone (DHEA), DHEA sulfate (DHEA-S), delta 4-androstenedione (delta 4A), and cortisol in the basal state and during prolonged adrenocorticotropin (ACTH) infusion (8 h) in a group of 34 individuals, 26 males and 8 females, with short stature. Their chronological ages (CA) ranged from 1.75 to 17.5 years (median 10.35 years). The subjects were grouped into two categories according to the results of pituitary testing: group 1 = short, non-GH-deficient (n = 16), and group 2 = GH-deficient, ACTH-sufficient (n = 18). Patients in groups 1 and 2 had similar bone ages (BA: 7.2 +/- 0.7 vs. 7.5 +/- 1.0 years) and Z scores for height (-3.0 +/- 0.2 vs. -3.2 +/- 0.3 units) and height velocity (-2.5 +/- 0.4 vs. -2.6 +/- 0.2 units). For both groups there were significant increases from basal to peak levels for DHEA, DHEA-S, delta 4A and cortisol following prolonged ACTH infusion. Although both basal and peak levels of DHEA-S overlapped in groups 1 and 2 for all CA and BA, levels in group 2 tended to be lower, especially for BA greater than 10 years.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of chronic clonidine treatment on urinary growth hormone excretion and linear growth in children with short stature

Eleven prepubertal children with short stature were treated with clonidine (0.15 mg/m2 daily) for a period of 1 year. The effect of this drug was evaluated on both clinical (growth velocity, height standard deviation scores for chronological age and bone age) and hormonal (urinary growth hormone excretion and insulin-like growth factor I) parameters. Our study shows that long-term clonidine administration in children with short stature did not result in significant differences in growth velocity, height standard deviation scores for chronological age and bone age, insulin-like growth factor I or in urinary growth hormone excretion.