ANTECEDENTS OF PEAK BONE MASS IN BLACK & WHITE WOMEN

这项研究的目的是调查环境、生物和 一大群(n=650)青年双胞胎的骨量遗传决定因素 参加NHLBI增长与健康研究的女性。11年 纵向数据是可用的，关于饮食摄入的数据是可用的， 体力活动，身体成分，青春期里程碑，怀孕， 口服避孕药的使用、吸烟和饮酒。这群人也是 同时参加第二项研究，该研究获得年度总人数 DEXA扫描到2000年。嵌套在此研究中，我们将1) 确定环境(当前和之前)和遗传因素 决定腰椎和股骨近端骨量(BMD)的因素 年龄在20-22岁；2)确定种族差异的影响 在目标1中发现的重要环境和遗传因素；以及 3)确定哪些环境和遗传因素会影响 骨代谢和钙稳态的生化标记物。骨 质量将通过几种不同的方式进行评估，部分原因是为了解决 人口的生物本性。将对变异进行基因分型 在与骨代谢和钙密切相关的遗传位点 动态平衡。生物标志物包括血清骨钙素和离子钙， 完整的甲状旁腺激素，尿N-端肽和钙。这个 主要假设涉及饮食中钙、维生素D、 体力活动、青春期成熟对骨密度的影响及其相互作用 彼此之间以及与基因类型之间的关系。我们将把注意力集中到 了解选定的环境和遗传因素的程度 影响公认的黑白骨密度差异的因素。 “暴露”的时机的相对重要性 环境因素将通过分析生物学中的数据进行评估 青春期里程碑定义的有意义的时间段。这项研究将 全面评估一套详尽的 骨/钙的环境指标、基因分型和生物标记物 动态平衡在测定BMD和确定种族中的作用 骨密度的差异。因此，通过利用效率和成本- 辛辛那提儿童医院正在进行的两项研究节省的资金 医院里，我们的研究可以“望远镜”的11年的跟踪发现 黑白儿童峰值骨量的重要先兆因素 女人。

The aim of this study is to investigate environmental, biologic, and genetic determinants of bone mass in a large (n=650) biracial of young women enrolled in the NHLBI Growth and Health Study. Eleven-year longitudinal data are available data are available on dietary intake, physical activity, body composition, pubertal milestones, pregnancy, oral contraceptive use, smoking, and alcohol intake. This cohort is also concurrently enrolled in a second study which obtains annual total body DEXA scans until year 2000. Nested within this study, we will 1) determine what environmental (current and antecedent) and genetic factors determine bone mass (BMD) at the lumbar spine and proximal femur at ages 20-22 years; 2) determine racial difference in the effects of the significant environmental and genetic factors found in aim #1; and 3) determine what environmental and genetic factors influence biochemical markers of bone metabolism and calcium homeostasis. Bone mass will be assessed several different ways in part to address the biethnic nature of the population. Genotyping will be done for variation at genetic loci intimately involved in bone metabolism and calcium homeostasis. Biomarkers include serum osteocalcin and ionized calcium, intact parathyroid hormone, and urinary N-telopeptides and calcium. The main hypotheses involve the effects of dietary calcium, vitamin D, physical activity, and pubertal maturation on BMD, and their interaction with each other as well as with genotypes. Attention will be directed to understanding the extent to which selected environmental and genetic factors influence the well-recognized black-white differences in BMD. The relative importance of the timing of "exposure" to these environmental factors will be assessed by analyzing data in biologically meaningful time periods defined by pubertal milestones. This study will provide a comprehensive evaluation of the role of an exhaustive set of environmental measures, genotypes, and biomarkers of bone/calcium homeostasis in determining BMD as well as in determining the racial differences in BMD. Thus, by capitalizing on the efficiency and cost- saving afforded by the two ongoing studies at Cincinnati Children's Hospital, our study can "telescope" the 11 years of follow-up to uncover important childhood antecedents of peak bone mass in black and white women.