ABSTRACT
Background@#Few studies using criterion measures of insulin sensitivity (SI) and insulin secretory capacity (ISC) have been conducted across puberty to adulthood. We examined how SI and ISC change from pre-puberty through adulthood. @*Methods@#Hyperglycemic clamp studies were performed in a convenience sample of non-Hispanic Black (NHB) and White children evaluated at age 6 to 12 years and at approximately 5-year intervals into adulthood (maximum age 27 years). SI and ISC (first-phase and steady-state insulin secretion) were determined cross-sectionally in 133 unique participants across puberty and in adulthood. Additionally, longitudinal changes in SI and ISC were compared at two timepoints among three groups defined by changes in pubertal development: pre-pubertal at baseline and late-pubertal at follow-up (n=27), early-pubertal at baseline and late-pubertal at follow-up (n=27), and late-pubertal at baseline and adult at follow-up (n=24). @*Results@#Cross-sectionally, SI was highest in pre-puberty and early puberty and lowest in mid-puberty (analysis of covariance [ANCOVA] P=0.001). Longitudinally, SI decreased from pre-puberty to late puberty (P<0.001), then increased somewhat from late puberty to adulthood. Cross-sectionally, first-phase and steady-state ISC increased during puberty and decreased in adulthood (ANCOVA P<0.02). Longitudinally, steady-state and first-phase ISC increased from pre-puberty to late puberty (P<0.007), and steady-state ISC decreased from late puberty to adulthood. The NHB group had lower SI (P=0.003) and greater first-phase and steady-state ISC (P≤0.001), independent of pubertal development. @*Conclusion@#This study confirms that SI decreases and ISC increases transiently during puberty and shows that these changes largely resolve in adulthood.
ABSTRACT
Background@#Few studies using criterion measures of insulin sensitivity (SI) and insulin secretory capacity (ISC) have been conducted across puberty to adulthood. We examined how SI and ISC change from pre-puberty through adulthood. @*Methods@#Hyperglycemic clamp studies were performed in a convenience sample of non-Hispanic Black (NHB) and White children evaluated at age 6 to 12 years and at approximately 5-year intervals into adulthood (maximum age 27 years). SI and ISC (first-phase and steady-state insulin secretion) were determined cross-sectionally in 133 unique participants across puberty and in adulthood. Additionally, longitudinal changes in SI and ISC were compared at two timepoints among three groups defined by changes in pubertal development: pre-pubertal at baseline and late-pubertal at follow-up (n=27), early-pubertal at baseline and late-pubertal at follow-up (n=27), and late-pubertal at baseline and adult at follow-up (n=24). @*Results@#Cross-sectionally, SI was highest in pre-puberty and early puberty and lowest in mid-puberty (analysis of covariance [ANCOVA] P=0.001). Longitudinally, SI decreased from pre-puberty to late puberty (P<0.001), then increased somewhat from late puberty to adulthood. Cross-sectionally, first-phase and steady-state ISC increased during puberty and decreased in adulthood (ANCOVA P<0.02). Longitudinally, steady-state and first-phase ISC increased from pre-puberty to late puberty (P<0.007), and steady-state ISC decreased from late puberty to adulthood. The NHB group had lower SI (P=0.003) and greater first-phase and steady-state ISC (P≤0.001), independent of pubertal development. @*Conclusion@#This study confirms that SI decreases and ISC increases transiently during puberty and shows that these changes largely resolve in adulthood.
ABSTRACT
Dianchi Lake is one of the most three seriously eutrophic lakes in China. In the present study, the phosphorus [P] and nitrogen [N] fractions in 37 surface sediments samples collected in the Dianchi Lake were investigated. The total phophorus [TP] in sediments was divided into two parts: inorganic P [IP] and residual P [Res-P]. The results showed that the total phosphorus content in surface sediments ranged from 1465.27 to 3650.12 mg/kg, IP was the major component of TP and the Ca bound P was the main fraction of IP. The bio-available phosphorus [BAP] in Dianchi Lake was first estimated in this study. BAP ranged from 215.66 to 678.02 mg/kgand the mean concentration was 382.78 +/- 89.77 mg/kgfor all 37 samples. The nitrogen fractions for the whole Dianchi Lake were firstly studied. It was shown that the sediment had been an important N nutrient source of the water, owing to the high content of transferable nitrogen forms in the sediment