Annals of the New York Academy of Sciences
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Ann. N. Y. Acad. Sci. · Sep 2000
Comparative StudyAge as a susceptibility factor in the striatal dopaminergic neurotoxicity observed in the mouse following substituted amphetamine exposure.
A number of substituted amphetamines, including methamphetamine (METH) are considered dopaminergic neurotoxicants. METH causes long-term depletions of striatal dopamine (DA) and its metabolites (DOPAC and HVA) that are accompanied by other changes indicative of nerve terminal degeneration. These include argyrophilia as detected by silver degeneration stains and an elevation in glial fibrillary acidic protein (GFAP), a marker of reactive gliosis in response to injury, as well as a long-term decrease in tyrosine hydroxylase (TH) protein levels. ⋯ In contrast, the usual neurotoxic regimen of d-METH was minimally effective in inducing GFAP elevations (49% over control) in one-month-old mice, despite elevations in body temperature equivalent to those observed in older mice. Although increasing the dosage of d-METH (20 to 80 mg/kg) did increase the GFAP response (100% over control), it was still well below that usually exhibited at the usual neurotoxic dosage (300-400% over control) in fully mature mice. These data suggest maturity of striatal dopamine systems may be an essential element in the striatal damage induced by the neurotoxic amphetamines.
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Ann. N. Y. Acad. Sci. · May 2000
Multicenter StudyWaist circumference and sagittal diameter reflect total body fat better than visceral fat in older men and women. The Health, Aging and Body Composition Study.
The validity of waist circumference and sagittal diameter as surrogate measures of visceral fat were assessed using preliminary cross-sectional data from the Health, Aging and Body Composition Study, a cohort of 3,075 men and women aged 70-79. Weight, body mass index, waist circumference, waist/thigh ratio, and sagittal diameter were compared by correlation, graphical analysis, and regression to total body fat as measured by dual-energy X-ray absorptiometry (Hologic 4500A), and to visceral fat area as measured by computerized tomography. ⋯ However, waist circumference, sagittal diameter, weight, and body mass index were more closely related to total body fat than to visceral fat area (R2 for the linear regression of waist circumference on total body fat was 0.69 in women and men; R2 for linear regression of waist circumference on visceral fat area was 0.40 in women, and 0.49 in men). These data suggest that the contribution of visceral fat to health risks will be better assessed by directly measuring this fat depot.