Obesity and Free Fatty Acid Flux

30%的美国人肥胖。妇女比男子受到的影响更严重。非洲裔美国人比白人更受影响。 为了了解肥胖的代谢后果，必须了解脂肪组织释放游离脂肪酸（FFA）的速率。循环FFA有助于肥胖症的并发症，特别是糖尿病和心脏病。由于所有这些疾病的患病率存在性别和种族差异，因此FFA通量可能存在性别和种族差异。FFA通量表示FFA循环的速率。FFA通量是同时进行的三个过程的结果，（1）FFA从脂肪组织释放的速率，（2）循环FFA用于能量的速率，以及（3）FFA离开循环重新进入脂肪组织的速率。没有关于FFA通量是否存在性别和种族差异的数据。此外，当比较不同体型、性别和种族的受试者时，不清楚FFA通量是否应根据瘦体重或静息能量消耗进行校正。 为了确定FFA通量是否存在性别和种族差异，并确保非洲裔美国人和高加索人的充分招募，这项调查是位于马里兰州贝塞斯达的美国国立卫生研究院（NIH）和明尼苏达州奥姆斯特德县的马约诊所之间的合作努力。美国国家卫生研究院所在的大华盛顿特区大都市区有一个大型的非洲裔美国人社区，而奥姆斯特德县90%以上的居民是白人。因此，美国国立卫生研究院将研究非裔美国人FFA通量的性别差异。将在马约诊所研究高加索人FFA通量的性别差异。将合并两项研究的结果，以确定FFA通量是否存在种族差异。 在NIH，将招募50名非洲裔美国人（25 M，25 W，年龄范围18-49岁）。将招募相同数量的正常体重、超重和肥胖受试者。作为门诊病人，参与者将接受两周的体重维持饮食，然后住院两天。在每个住院早晨，将测量静息能量消耗，并输注稳定同位素以测量FFA通量。稳定同位素是元素的天然存在形式，安全且无放射性。 从美国国立卫生研究院对非裔美国人的研究中，将有可能确定（a）非裔美国人的FFA释放率是否与瘦体重或静息能量消耗高度相关，以及（B）这种关系是否存在性别差异。然后如上所述，将结合马约诊所和NIH的结果，以确定FFA通量是否存在种族差异。

Thirty percent of Americans are obese. Women are more severely affected than men. African-Americans are more severely affected than Caucasians. To understand the metabolic consequences of obesity, it is essential to know the rate at which free fatty acids (FFA) are released from adipose tissue. Circulating FFA contribute to the complications of obesity particularly diabetes and heart disease. As there are sex and race differences in the prevalence of all these conditions there may be sex and race differences in FFA flux. FFA flux represents the rate at which FFA circulate. FFA flux is the result of three processes going on at the same time, (1) the rate FFA are released from adipose tissue, (2) the rate circulating FFA are used for energy, and (3) the rate FFA leaves the circulation to re-enter adipose tissue. No data is available on whether sex and race differences in FFA flux exist. Further, when comparing subjects of different size, sex and race, it is unknown whether FFA flux should be corrected for lean body mass or resting energy expenditure. To determine if there are sex and race differences in FFA flux and to ensure adequate enrollment of both African American and Caucasians, this investigation is a collaborative effort between the National Institutes of Health (NIH) in Bethesda, Maryland and the Mayo Clinic in Olmsted County, Minnesota. The greater Washington, DC, metropolitan area, where NIH is located, has a large African-American community whereas over 90% of residents of Olmsted County are Caucasians. Therefore, sex differences in FFA flux in African Americans will be studied at the National Institutes of Health. Sex differences in in FFA flux Caucasians will be studied at the Mayo Clinic. The results of the two studies will be combined to determine if there are race differences in FFA flux. At NIH, 50 African-Americans (25M, 25W, age range 18-49 years) will be enrolled. Equal numbers of normal weight, overweight and obese subjects will be recruited. As outpatients, participants will be placed on weight maintaining diets for two weeks and then admitted for a two-day hospital stay. On each in-hospital morning, resting energy expenditure will be measured and stable isotopes infused to measure FFA flux. Stable isotopes are naturally occurring forms of elements, which are safe and non-radioactive. From the study of African-Americans at NIH it will be possible to determine if (a) the rate of FFA release in African-Americans is more highly related to lean body mass or to resting energy expenditure, and (b) if there is a sex difference in this relationship. Then as described above, the results from the Mayo Clinic and NIH will be combined to determine if there are race differences in the FFA flux.