主页 > 医学动态 >

【medical-news】《Nature》：新旧交替 肥胖仍然在继

And the Fat Goes On 该文本人已认领，若四十八小时未给出结果，请其他战友自由认领 To dieters struggling to lose weight, it may seem like new fat keeps showing up. That impression is half-right. Contrary to the accepted wisdom that humans don't make new fat cells, scientists have found that our bodies constantly generate fresh cells each year to replace those that naturally die off. Although the finding may not directly help people shed pounds, it suggests that our bodies tightly regulate the number of fat cells. And that mechanism, not yet understood, may help explain why it's so difficult to lose weight.
在艰难的减肥而节食,似乎新的脂肪又产生了。这个印象只对了一半。人体不再产生新的脂肪细胞，与这个广泛接受的结论相反，科学家们发现：我们的体内每年都在不断的产生新的细胞来替代自然衰老死亡的细胞。虽然这个发现对人减轻体重没有直接的帮助，但是这个研究表明：我们的身体密切的调节着脂肪细胞的数目。虽然这个机制现在还不清楚，但是可能有助于解释减轻体重为何这么困难。
Researchers have assumed that a human can't make new fat cells, because the total amount of the cells doesn't seem to change after reaching adulthood. The trouble with testing this assumption is that standard techniques for tracking cells in animals are either toxic to people or can't be applied to fat cells. To get around this problem, a team that included Kirsty Spalding, a molecular biologist at the Karolinska Institute in Stockholm, Sweden, used data from aboveground nuclear tests conducted from 1955 to 1963. The tests spewed vast amounts of the radioactive molecule, carbon-14, into the atmosphere, which in turn was incorporated into the DNA of the fat cells of humans. Carbon-14 concentrations in the fat cells correspond to levels present in the atmosphere when the cells were created, giving the researchers a way to date when the cell was born.
研究人员以前认为人类不能再产生新的脂肪细胞了。因为成年后，细胞的总数似乎不再发生变化了。验证这条假设的困难是：在动物身上跟踪细胞的标准技术不是对人有毒就是不能适用于脂肪细胞。为解决这个问题，一个包括Kristy Spalding的小组，使用了1955到1963年地上核试验产生的数据。这些试验向空气中喷发了大量的放射性分子——碳-14。这些分子被导入到了人类脂肪细胞的DNA中。碳-14的在脂肪细胞中的浓度与当时细胞产生时候空气中的碳-14的浓度相关，这给研究人员提供了一条测知细胞产生日期的道路。
In 10 lean or obese adults born before the nuclear bomb testing began, the carbon-14 concentrations in fat cells matched levels present in the atmosphere during the tests, indicating the fat cells were generated later in life. Conversely, fat cells from 25 lean or obese people born after the testing was halted had carbon-14 concentrations lower than the levels present during the bomb testing years. The carbon-14 amounts were closer to current atmospheric levels of the radioactive compound, indicating that the fat cells were generated later in life and confirming that the cells are continuously generated during our adult years, the researchers report this week in Nature. Using the carbon-14 data, the age of the study participants and their total number of fat cells, the researchers calculated that people generate about 10% of their fat cells each year to replace an equivalent amount that die off. The total stays the same, giving the illusion that fat cells aren't dying.
十个出生于核爆炸试验开始之前的瘦或胖的成年人，其脂肪细胞碳-14的浓度和在试验中暴露在大气中的浓度水平相符合。这提示：这些脂肪细胞是后来的生活中产生的；同时这也证明：在我们成年后细胞是持续的产生，研究人员本周在Nature上报道。使用碳-14数据、研究参与者的年龄和他们总的脂肪细胞数，研究者计算得出：人类每年大约产生10%的脂肪细胞来替换等量的死亡细胞。细胞总量维持不变，这使人们产生了脂肪细胞不死亡的错觉

The researchers also monitored fat cell numbers in 20 people who underwent gastric bypass operations. Weight loss after the surgery was due to shrinkage of their fat cells, but the total number of the cells stayed constant. This indicates that even when people eat less, their bodies continue to churn out new fat cells to ensure the levels stay the same.
研究者也监视了20位进行了胃旁手术的人的脂肪细胞数目。术后体重的降低是由于他们的脂肪细胞收缩，但是细胞的总量维持不变。这指示即使人吃的更少，他们的体内仍然继续产生新的脂肪细胞来保证数量水平不变。
How the body regulates the turnover of fat cells remains unknown. But Spalding says the fact that the body keeps up the fat cell production even during weight loss could be one reason why people find it hard to keep off any weight they lose.

阅读本文的人还阅读：

【medical-news】干扰素r和

【medical-news】呼吸道病毒

【bio-news】抗肥胖可否抵

作者:admin@医学,生命科学    2010-10-03 17:11
医学,生命科学网