Bone mineral density obtained by peripheral quantitative computed tomography (pQCT) in middle-aged and elderly Japanese.

To clarify age-related changes in bone mineral density (BMD) by peripheral quantitative computed tomography (pQCT), 1,124 Japanese middle-aged and elderly community-dwelling people were examined. The BMD of the trabecular bone was assessed at the distal part of the radius (D50), and the BMD of the cortical bone was assessed at the diaphysis of the radius (P100). P100 during age 40 to 49 was significantly higher in females (1359.6 +/- 10.7 mg/cm3, mean +/- SE) than in males (1253.5 +/- 9.5 mg/cm3), while there was no difference in D50, 245.3 +/- 5.1 mg/cm3 in females and 293.0 +/- 5.5 mg/cm3 in males. Females and males aged 50 to 59 lost 8.09 +/- 2.08 (mean +/- SE) mg/cm3 and 3.80 +/- 1.77 mg/cm3 of D50 every year, respectively. As for P100, females lost 25.1 +/- 4.48 mg/cm3, and males lost 6.37 +/- 3.89 mg/cm3 every year. Because of these gender differences, both D50 and P100 were significantly higher in males than in females aged 50 and over. Assuming that the average BMD between ages 40 and 44 was the maximum bone mineral density (BMD max), the percentage change from the BMD max with age was examined. Females aged 60 to 69 whose BMD were under 70% of the BMD max made up 73.9% in D50 and 23.2% in P100. Only 21.1% of males aged 60 to 69 showed less than 70% of the BMD max in D50 and only 3.8% in P100. The percentage decrease in BMD by age was larger in D50 than in P100 in both males and females. The individual difference in BMD was larger in D50 than in P100. These results suggest that pQCT may be useful to independently assess aging effects on cortical and trabecular bone density.

Background Previous investigators have reported that maximal power increases during growth and decreases with aging. These age-related differences have been reported to persist even when power is scaled to body mass or muscle size. We hypothesized that age-related differences in maximal power were primarily related to differences in muscle size and fiber-type distribution rather than to age per se. Methods Maximum cycling power (P max ) and optimal pedaling rate (V opt , a surrogate measure for muscle fiber type) were determined for 195 boys and men, 8-70 years of age, by using inertial load cycle ergometry. Anthropometric dimensions were used to estimate lean thigh volume (LTV est ) of all subjects, and magnetic resonance imagery was used to determine thigh and hip muscle volume (MRI vol ) for 24 subjects. Results P max was highly related to the product of LTV est and V opt (LTV est × V opt ; r 2 = 0.83). Multiple regression revealed that P max was significantly related to both LTV est × V opt and age (r 2 = 0.84). Power scaled by LTV est × V opt was stable during growth and exhibited a small but significant decrease with aging. MRI vol was highly correlated with LTV est , and the ratio of LTV est to MRI vol was independent of age. Conclusions These results suggest that muscle volume and optimal pedaling rate are the main determinants of maximal power across the lifespan and that the contractile properties of muscle are developed early in childhood and remain nearly intact late into the lifespan. To clarify age-related changes in bone mineral density (BMD) by peripheral quantitative computed tomography (pQCT), 1,124 Japanese middle-aged and elderly community-dwelling people were examined. The BMD of the trabecular bone was assessed at the distal part of the radius (D50), and the BMD of the cortical bone was assessed at the diaphysis of the radius (P100). P100 during age 40 to 49 was significantly higher in females (1359.6 ± 10.7 mg/cm 3 , mean ± SE) than in males (1253.5 ± 9.5 mg/cm 3 ), while there was no difference in D50, 245.3 ± 5.1 mg/cm 3 in females and 293.0 ± 5.5 mg/cm 3 in males. Females and males aged 50 to 59 lost 8.09 ± 2.08 (mean ± SE) mg/cm 3 and 3.80 ± 1.77 mg/cm 3 of D50 every year, respectively. As for P100, females lost 25.1 ± 4.48 mg/cm 3 , and males lost 6.37 ± 3.89 mg/cm 3 every year. Because of these gender differences, both D50 and P100 were significantly higher in males than in females aged 50 and over. Assuming that the average BMD between ages 40 and 44 was the maximum bone mineral density (BMD max ), the percentage change from the BMD max with age was examined. Females aged 60 to 69 whose BMD were under 70% of the BMD max made up 73.9% in D50 and 23.2% in P100. Only 21.1% of males aged 60 to 69 showed less than 70% of the BMD max in D50 and only 3.8% in P100. The percentage decrease in BMD by age was larger in D50 than in P100 in both males and females. The individual difference in BMD was larger in D50 than in P100. These results suggest that pQCT may be useful to independently assess aging effects on cortical and trabecular bone density.

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Normal lumbar vertebrae: anatomic, age, and sex variance in subjects at proton MR spectroscopy -initial experience D. Schellinger, C. S. Lin, D. Fertikh, J. S. Lee, W. C. Lauerman, F. Henderson and B. Davis Radiology 2000;215:910-16 Fifty-seven subjects underwent proton magnetic resonance (MR) spectroscopy of the second lumbar vertebra to evaluate single-voxel and multivoxel techniques. Measurements included lipid-to-water ratios, lipid fractions, and line width. These data provide information about vertebral fat content. There was an age-dependent linear increase in fat content and sex dependence. A higher fat concentration was found in men. The observed spectra provide a basis for future study to determine clinical utility of vertebral proton MR spectroscopy. H. Tohgi, T. Abe, K. Yamazaki, T. Murata, E. Ishizaki and C. Isobe Neurosci Lett 1999;269:52-4 To investigate the significance of nitric oxide (NO)-mediated neuron death in aging and Alzheimer's disease (AD), the 3-nitrotyrosine concentration in the cerebrospinal fluid (CSF) was investigated in neurologically normal controls and patients with AD. The 3-nitrotyrosine concentration and the 3-nitrotyrosine/tyrosine ratio significantly increased with advancing age, whereas the tyrosine concentration was unaltered. In patients with AD, the 3-nitrotyrosine concentration and the 3-nitrotyrosine/tyrosine ratio increased significantly (>six-fold) compared with controls of similar age, and increased significantly with decreasing cognitive functions, whereas the tyrosine concentration did not change. These findings suggest that an activation of tyrosine nitration, increase in nitrated tyrosine-containing proteins, and/or its degradation may be involved in brain aging and play an important role in the pathogenesis of AD.

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Population aging in developing countries L. B. Shrestha Health Aff (Millwood) 2000;19:204-12 Issues related to population aging -Social Security and pension reform, health care financing and provision, and long-term care -have long been the subject of public debate in the industrialized countries of Europe and North America.
Economically less developed regions have been slower to adopt aging as a major public policy concern, despite the fact that older populations in many developing countries are growing more rapidly than are those of industrialized nations.

Worldwide literature review
The Aging Male 157