BONE AND MINERAL METABOLISM IN BLACKS AND WHITES

有证据表明，与黑色相比，黑色的骨量增加 白人个体，因此患骨质疏松症的风险较小 相关骨折。骨骼质量的增加归因于 肌肉质量增加。此外，黑人的尿钙低于 穿着白色衣服。据认为，黑人骨量的增加 由于骨骼对甲状旁腺激素(PTH)的抵抗，可能 1，25-二羟基维生素D[1-25(OH)2D]和减少尿量 循环中甲状旁腺激素随之增加而引起的钙。初步 结果支持这一假设：年轻的成年黑人(20-35岁) 平均血清免疫反应性甲状旁腺素、血清 1，25(OH)2D和尿环AMP显著降低 与年龄匹配的白人相比，尿钙。平均血钙， 血清离子钙、血磷和内生肌酐清除率是 两组疗效相同。鉴于这些观察，更多的研究 被提出a)以确定黑人的骨骼对 通过测定对人合成甲状旁腺素(1-34)的反应以及是否 黑人肠道对钙的吸收增加是因为 增加循环1，25(OH)2D，b)以确定骨骼是否 黑色对1，25(OH)2D3的抗性以及结合和摄取 培养的皮肤成纤维细胞的~3H-1，25(OH)2D3在黑人中减少，c) 确定骨量和骨骼增加的年龄 对甲状旁腺素的抗药性在黑人中变得明显，d)为了确定 黑人前臂、腰椎和髋部3个部位骨量的增龄 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量的能力受损 发生在白人中，e)以确定更年期对维生素的影响 D和黑人女性的矿物质代谢，以及f)以确定其影响 肥胖者的体重增加和肌肉质量的增加 健美运动员和举重运动员的骨量、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，说明为什么 骨骼抵抗骨质疏松症和尿路疾病的发展。 黑人体内的钙含量减少了，而由 重力会影响骨量并导致骨密度的改变 维生素D--内分泌系统类似于黑人身上观察到的。这个 结果也可能导致调查的新方法 骨质疏松症的发病机制及治疗。

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.