Klinefelter syndrome.
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Abnormalities, Multiple↗
Biomedical subjects
Alan D Rogol
Publications and source records attributed to Alan D Rogol.
Androgens and puberty.
Growth, adolescent sexual development and changes in body composition are described in male adolescents. The underlying changes in the hypothalamic-pituitary gonadal and the GH/IGF-I axes that underline the physical changes are then described. Finally, how high energy output, at a time of low energy input, using, as an example, scholastic male wrestlers, is described.
Adolescent↗
Growth at puberty.
Somatic growth and maturation are influenced by a number of factors that act independently or in concert to modify an individual's genetic potential. The secular trend in height and adolescent development is further evidence for the significant influence of environmental factors on an individual's genetic potential for linear growth. Nutrition, including energy and specific nutrient intake, is a major determinant of growth. Paramount to normal growth is the general health and well-being of an individual; in fact, normal growth is a strong testament to the overall good health of a child. More recently the effect of physical activity and fitness on linear growth, especially among teenage athletes, has become a topic of interest. Puberty is a dynamic period of development marked by rapid changes in body size, shape, and composition, all of which are sexually dimorphic. One of the hallmarks of puberty is the adolescent growth spurt. Body compositional changes, including the regional distribution of body fat, are especially large during the pubertal transition and markedly sexually dimorphic. The hormonal regulation of the growth spurt and the alterations in body composition depend on the release of the gonadotropins, leptin, the sex-steroids, and growth hormone. It is very likely that interactions among these hormonal axes are more important than their main effects, and that alterations in body composition and the regional distribution of body fat actually are signals to alter the neuroendocrine and peripheral hormone axes. These processes are merely magnified during pubertal development but likely are pivotal all along the way from fetal growth to the aging process.
Adipose Tissue↗
Effects of dose and gender on the growth and growth factor response to GH in GH-deficient children: implications for efficacy and safety.
We evaluated the dose-response effects of GH on the growth and growth factor levels of GH-deficient patients. One hundred eleven short (-3.0 +/- 0.9 height SD score), prepubertal GH-deficient children were randomized to receive low- (L; 0.025 mg/kg per day), medium- (M; 0.05 mg/kg per day), or high- (H; 0.1 mg/kg per day) dose GH. One hundred four children completed the 2-yr study. At 2 yr, the three groups displayed increases in height SD scores of 1.4 +/- 0.1 for L, 2.2 +/- 0.1 for M, and 2.3 +/- 0.1 for H (P < 0.001 relative to L, P = NS relative to M). The serum levels of IGF-I and IGF binding protein-3 during treatment also demonstrated dependency on the GH dose and were independently correlated with the increase in height SD scores attained. Bone age advancement, the occurrence of puberty, fasting glucose, and hemoglobin A1c did not change during therapy, but fasting insulin levels rose in a dose-dependent manner. Surprisingly, the GH dose-response curve for both auxological and biochemical parameters differed between prepubertal females (n = 33) and males (n = 71). Males had a linear GH dose response, whereas females had an apparent plateau of both linear growth and IGF-I SD score responses at 0.05 mg/kg per day. In this large, randomized, 2-yr study, we observed a dose-response effect of GH on growth and serum growth factor levels and a prepubertal gender difference in GH sensitivity. These results suggest that the efficacy and theoretical safety of GH therapy can be optimized by modulating the GH dose in a gender-specific manner, based on the growth response and serum growth factor levels.
Age Factors↗