Wrap up Warm to Avoid Heart Attacks, Newscientist, July 5th, 2013
冬天穿暖和能避免心脏病发作，新科学家科技杂志，2013年7月5日
When it's cold we turn up the central heating.
当天气寒冷时，我们会打开中央供暖系统。
Our bodies do the same-burning brown fat to produce extra heat and keep us warm.
我们的身体也是一样，我们会燃烧褐色脂肪来产生额外的热量，以保持我们身体的温暖。
But this internal heating system may have a dangerous side effect.
但是这种内部加热系统可能会有危险的副作用。
"Brown fat has always been considered to be good fat." says Yihai Cao at the Karolinska Institute.
卡罗林斯卡医学院的曹义海说:“褐色脂肪一直被认为是不错的脂肪。”
Since it turns the energy obtained from food into heat, brown fat thought to be one of the keys to weight loss.
由于事实证明热量是由食物中所获得的能量转化而来的，所以褐色脂肪被认为是减肥的关键之一。
Cao and colleagues wanted to investigate its role in atherosclerosis-the build-up of fatty deposits in blood vessels.
曹义海和他的同事们想探讨褐色脂肪在动脉硬化中所扮演的角色，动脉硬化指的是脂肪在血管中的沉积。
First, the team created genetically modified mice that were easily prone to atherosclerosis.
首先，研究团队创造出了一种转基因老鼠，这些老鼠特别容易发生动脉硬化。
At eight weeks old, they split the mice into two groups.
在老鼠8周大的时候，研究人员把老鼠分成了两组。
Some mice were kept for a further eight weeks at 30°C-a temperature that mice find comfortable-while the rest were kept at 4℃.
一组老鼠在30°C的温度下继续待8周，这个温度会让老鼠感觉很舒适，而另一组老鼠将待在4°C的温度下。
Mice exposed to the cold converted more white fat to brown and the production of low-density lipoprotein (LDL) was accelerated, leading to a greater build-up of fatty deposits.
暴露于寒冷环境下的老鼠能将更多的白色脂肪转化成褐色脂肪，加快生产低密度的脂蛋白，从而导致更多脂肪的沉积。
The mice kept in the cold also had deposits in their blood vessels that were more likely to break off and cause blockages-a major cause of heart attack and stroke.
同时，在寒冷环境下饲养的老鼠的血管中也会有沉积，这更容易造成血管的中断，导致堵塞，这是心脏病发作和中风的一个重要原因。
To test whether the effect was specifically linked to heat generation, the team next created atherosclerosis-prone mice that were unable to use their brown fat to produce heat.
为了测试这种结果是否与产生的热量有关，研究人员接下来创造出易发生动脉硬化的老鼠，它们无法使用褐色脂肪产生热量。
These mice were completely protected from the increased production of LDL and consequent arterial problems.
这些老鼠完全在生产量提高的低密度脂蛋白的保护下，结果产生了动脉问题。
But Andrew Whittle at the University of Cambridge notes that mice kept in the cold will eat more food, which might also contribute to the extra fatty deposits.
但是剑桥大学的安德鲁·惠特尔指出，老鼠在寒冷的环境中会吃更多的食物，这可能也有助于多余脂肪的沉积。
Until recently we did not know adult humans had brown fat at all, he says, and we are still learning what it does.Thank you.
曹义海说，直到最近，我们根本不知道成年人体内是否有褐色脂肪，我们仍然在研究其作用。谢谢。
