Heart Disease Risk Factors In African Americans

182名非糖尿病非洲裔美国人（74名男性，108名女性）参加了研究。参与者的年龄范围为20至50岁。该非裔美国人样本可被视为具有代表性，因为肥胖（43%）、葡萄糖耐受不良（22%）和高血压（21%）的患病率与NHANES数据相似。NHANES代表国家健康和营养检查，是一项有数千名参与者的全国性调查。参与者的范围从非常瘦到非常胖。参与者的平均体重指数为30.6公斤/平方米（范围18.5 - 54.7）。身体质量指数是一种数学方法，用于根据身高校正体重。由于参与者的体重指数范围很广，因此可以得出关于体型与胰岛素抵抗关系的结论。我们在非裔美国男性中发现，男性腰围102厘米预示着胰岛素抵抗和肥胖。因此，我们完全同意国家胆固醇教育计划对白人的价值观。然而，在非裔美国妇女中，我们发现腰围98厘米预示着胰岛素抵抗和肥胖。根据对白色女性的调查，国家胆固醇教育计划建议使用腰围阈值88 cm。因此，我们的工作表明，有必要对妇女的指导方针进行种族特定的修改。 TG升高和HDL降低被认为是胰岛素抵抗的脂质标志。然而，虽然TG升高是白人胰岛素抵抗的标志物，但我们已经证明TG不是非裔美国人胰岛素抵抗的标志物。TG与胰岛素抵抗关系的研究已成为本研究的重要组成部分，参与本方案的非裔美国人队列现在被称为非裔美国人甘油三酯和心血管风险的塔拉。塔拉的结果令人印象深刻，以至于TG不是非裔美国人胰岛素抵抗标志物的假设在1999-2001年的NHANES数据中得到了检验。在这个全国性的白人、非洲裔美国人和墨西哥裔美国人的数据集中，TG不是胰岛素抵抗的标志物的事实得到了证实。然而，TG是白人和墨西哥裔美国人胰岛素抵抗的标志物。这再次表明需要有针对具体族裔的指导方针。 为了开发游离脂肪酸对胰岛素敏感性的指数，我们正在与数学家合作。建模正在进行中。胰岛素对葡萄糖水平影响的模型是在20世纪80年代由Richard N。伯格曼及其同事。由于影响游离脂肪酸水平的激素的多样性以及游离脂肪酸比葡萄糖更广泛的生物变异范围，因此获得胰岛素对游离脂肪酸的影响的模型是一个更大的挑战。为了建立模型，塔拉的150名参与者经常进行静脉葡萄糖试验，在3至6小时内的36个时间点测定葡萄糖、胰岛素和游离脂肪酸水平。复杂的多室建模正在进行中。 在过去的一年里，有50多名居住在华盛顿特区大都市区的非洲黑人被招募。我们正在了解到，生活在美国的非洲黑人在年龄、性别和BMI方面的代谢健康程度低于非洲裔美国人，包括胰岛素抵抗、葡萄糖耐量和血脂。这部分队列将被称为BART非洲黑人和风险有关TG水平和其他代谢因素。对数据的分析正在进行中，但与AA相比，BA的代谢健康较低的一个原因可能是一旦移民到美国，BA的体重相对较快。

One hundred eighty-two nondiabetic African-Americans (74 Men, 108 Women) have participated. The age range of the participants is 20 to 50 years. This sample of African Americans can be considered representative because the prevalence of obesity (43%), glucose intolerance (22%) and hypertension (21%) is similar to NHANES data. NHANES stands for National Health and Nutrition Examination and is a nationwide survey with thousands of participants. The participants range from very lean to very obese. The mean body mass index of participants is 30.6 kg/m2 (range 18.5 54.7). Body mass index is a mathematical method used to correct weight for height. Due to the broad range of body mass index in the participants it is possible to make conclusions about the relationship of body size to insulin resistance. We have found in African American men that a waist circumference of 102 cm in men predicts both insulin resistance and obesity. Therefore we are completely in agreement with the National Cholesterol Education Program values for whites. However, in African American women we found that a waist circumference of 98 cm predicted both insulin resistance and obesity. Based on investigations in white women the National Cholesterol Education Program recommends that a waist circumference threshold of 88 cm be used. Therefore our work demonstrates the need for ethnic specific modifications of guidelines in women. Elevated TG and low HDL are considered lipid hallmarks of insulin resistance. However while elevated TG is a marker of insulin resistance in whites, we have shown that TG is not a marker of insulin resistance in African Americans. The investigation of the relationship of TG to insulin resistance has become such an important component of this research, that the cohort of African Americans participating in this protocol are now known as TARA for Triglyceride and Cardiovascular Risk in African Americans. Results from TARA were so impressive that the hypothesis that TG was not a marker of insulin resistance in African Americans was tested in NHANES data from 1999-2001. In this nationwide data set of whites, African Americans and Mexican Americans, the fact that TG was not a marker of insulin resistance was confirmed. However, TG was a marker of insulin resistance in whites and Mexican Americans. Again this demonstrates the need for ethnic specific guidelines. To develop an index of free fatty acid sensitivity to insulin, we are working with mathematicians. The modeling is underway. The modeling of the influence of insulin on glucose levels was done in the nineteen eighties by Richard N. Bergman and colleagues. Because of the multiplicity of hormones that affect free fatty acid levels as well as the much wider range of biological variation in free fatty acids than glucose, achieving a model of the effect of insulin on free fatty acids is an even greater challenge. To achieve a model 150 participants in TARA have had frequently sampled intravenous glucose tests with glucose, insulin and free fatty acids levels determined at 36 timepoints in a 3 to 6 hour period. The complex multicompartment modeling is underway. In the last year over 50 Black Africans living in the Washington DC metropolitan area have been recruited. We are learning that Black Africans living in the United States matched by age, sex and BMI are less metabolically healthy in terms of insulin resistance, glucose tolerance and lipid profile than African Americans. This part of the cohort will be known as BART for Black Africans and Risk regarding TG levels and other Metabolic Factors. Analyses of the data is underway, but one reason for the lower metabolic health in BA comparing to AA may be the relatively rapid weight BA experience once emigration to the United States occurs.