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Birds Show Price Humans Pay for Good Clotting

They say what doesn’t kill you makes you stronger. But sometimes what makes you stronger can kill you, at least when it comes to blood clotting. Because the stickiness that allow platelets to heal your wounds also raises your risk of heart attack.
人们总说杀不死你的，能让你更强大。但有时候，你却可能死于一些令你强大的因素。至少就血液凝固这一人类优势来说，能证实这一观点。因为粘稠的血小板不但能愈合我们人类的创伤，同时也会增加我们患心脏病的危险。

All mammals use platelets to help prevent blood loss after traumatic injury. But birds don’t have ‘em, nor do reptiles or fish. Instead, these critters have blood cells called thrombocytes, which are about twice the size of platelets. But is bigger necessarily better when it comes to clotting? Scientists took thrombocytes from parakeets and put them to the test. The work appears in the journal Blood. [Alec A. Schmaier et al., "Occlusive thrombi arise in mammals but not birds in response to arterial injury: evolutionary insight into human cardiovascular disease"]
所以哺乳动物在遭受创伤后都是依靠血小板来防止出血过多。但是鸟类、鱼类以及爬行类动物没有这一功能。它们体内有一种凝血细胞，是我们血小板的两倍大。但是不是凝血细胞越大，凝血效果就越好呢？科学家提取了鹦鹉体内的凝血细胞，进行实验。实验结果刊登在‘Blood’这本期刊上。

They focused their attention on birds because our feathered friends have a cardiovascular system much like our own, in that blood exerts pressure on the walls of blood vessels.
科学家们之所以把注意力集中在了小鸟上，是因为在我们那长满羽毛的朋友体内，血液施加给血管壁的压力我们人类的相像。可以说我们有相似的心血管系统。

The results: parakeet thrombocytes don’t stick together like platelets do. They also don’t block blood flow in the birds’ arteries the same way that platelets do when they form clots in mice.
实验的结果是：鹦鹉的凝血细胞不如我们人类的血小板那么给力。它们也不能在鸟类的动脉中起到类似血小板在小白鼠体内的凝块作用。

Which means that mice may be more likely to survive a bloodletting-pecking. But birds are far less likely to suffer from the clot formation called economy class syndrome—despite being frequent fliers.
这就意味着小白鼠更可能在浴血肉搏中幸存下来。但尽管小鸟是空中常客，它们不太可能患上我们容易患上的经济舱综合征。

ps： 简单介绍一下“经济舱综合征”，因长时间飞行后，腿部肿胀的症状。在经济舱中病发几率更高，因为经济舱的狭小空间，使乘客的腿部长时间不能自由动弹。因此，血液容易积压在腿部，增加了血块凝结的可能性。

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