BONE AND MINERAL METABOLISM IN BLACKS AND WHITES

有证据表明，骨量增加，黑色相比， 白色个体，从而降低患骨质疏松症的风险， 相关骨折。 增加的骨骼质量归因于 增加肌肉质量。 此外，黑人的尿钙低于 穿白色的 有人提出，黑人骨量的增加 甲状旁腺激素（PTH）的骨骼阻力的结果， 1，25-二羟维生素D [1-25（OH）2D]， 钙引起的循环PTH随之增加。 初步 结果支持这一假设：年轻的成年黑人（年龄20-35岁） 显示平均血清免疫反应性PTH、血清 1，25（OH）2D和尿环AMP，平均 与年龄匹配的白人相比， 平均血清钙， 血清离子钙、血清磷和肌酐清除率是 两组相同。 鉴于这些观察结果， 建议a）建立黑人的骨骼是抵抗 通过测定对人合成PTH（1-34）的反应以及是否 黑人的肠道钙吸收增加， 增加循环1，25（OH）2D，B），以确定骨骼是否 黑人对1，25（OH）2D 3具有抗性， 3 H-1，25（OH）2D 3通过培养的皮肤成纤维细胞在黑人中减少，c） 以确定骨量和骨骼增加的年龄， 对PTH的抗性在黑人中变得明显，d）为了确定 年龄对黑人前臂、腰椎和髋关节3个部位骨量的影响， 以及是否存在与年龄相关的肾脏产生1，25（OH）2D的损失 以及黑人适应低钙摄入的能力受损， 发生在白人，e）以确定绝经对维生素C的影响。 D和矿物质代谢在黑人妇女，和f），以确定影响 肥胖受试者体重增加， 健美运动员和举重运动员对骨量和维生素D和矿物质 新陈代谢. 拟议的工作应该提供新的信息， 骨骼对骨质疏松症和泌尿系统疾病的发展具有抵抗力。 钙在黑人中减少， 重力会影响骨量， 维生素D-内分泌系统与黑人相似。 的 研究结果也可能导致新的方法来调查 骨质疏松症的发病机制和治疗。

There is evidence that bone mass is increased in black as compared to white individuals so that there is less risk of osteoporosis and associated fractures. The increased skeletal mass is attributed to increased muscle mass. Further, urinary calcium is lower in blacks than in whites. It is proposed that the increase in bone mass in blacks results from skeletal resistance to parathyroid hormone (PTH) and possibly to 1,25-dihydroxyvitamin D [1-25(OH)2D] and that diminished urinary calcium caused by consequent increases in circulating PTH. Preliminary results support this hypothesis: young adult blacks (age 20-35 years) show significant increases in mean serum immunoreactive PTH, serum 1,25(OH)2D and urinary cyclic AMP and significant decreases in mean urinary calcium as compared to age-matched whites. Mean serum calcium, serum ionized calcium, serum phosphorus and creatinine clearance are the same in the two groups. In view of these observations, additional studies are proposed a) to establish that the skeleton of blacks is resistant to PTH by determining the response to human synthetic PTH (1-34) and whether intestinal absorption of calcium is increased in blacks because of increased circulating 1,25(OH)2D, b) to determine whether the skeleton of blacks is resistant to 1,25(OH)2D3 and whether binding and uptake of 3H-1,25(OH)2D3 by cultured skin fibroblasts are diminished in blacks, c) to determine the age at which increases in bone mass and skeletal resistance to PTH become evident in blacks, d) to determine the effects of aging on bone mass at 3 sites in blacks, forearm, lumbar spine and hip, and whether there is an age-related loss of renal production of 1,25(OH)2D and impairment in ability to adapt to a low calcium intake in blacks as occur in whites, e) to determine the influence of the menopause on vitamin D and mineral metabolism in black women, and f) to determine the effects of increased body weight in obese subjects and of increased muscle mass in body builders and weight lifters on bone mass and vitamin D and mineral metabolism. The proposed work should provide new information about why the skeleton is resistant to the development of osteoporosis and urinary calcium is reduced in blacks and whether increased strain produced by gravitational forces can influence bone mass and produce alterations in the vitamin D-endocrine system similar to those observed in blacks. The results could also lead to new approaches for investigating the pathogenesis and treatment of osteoporosis.