电脑模型解析镰状细胞危象形成

海量资料下载 免费学习 www.englishvip.com/xinlw.htm （申请网址） Using powerful computer models, researchers from Brown University have shown for the first time how different types of red blood cells interact to cause sickle cell crisis, a dangerous blockage of blood flow in capillaries（毛细血管） that causes searing pain and tissue damage in people with sickle cell disease. The models showed that the rigid, crescent-shaped red blood cells that are the hallmark of sickle cell disease don't cause these blockages on their own. Instead, softer, deformable red blood cells known as SS2 cells start the process by sticking to capillary walls. The rigid sickle-shaped cells then stack up behind the SS2s, like traffic behind a car wreck.   The findings, published in Proceedings of the National Academy of Sciences, could provide a way to evaluate drug treatments aimed at easing or preventing sickle cell crisis, also known as vaso-occlusion.   "This is the first study to identify a specific biophysical mechanism through which vaso-occlusion takes place," said George Karniadakis, professor of applied mathematics at Brown and the study's senior author. "It was a surprising result because the common wisdom was that it was just the sickle cells that block the capillary."   Sickle cell disease is a genetic condition that affects an estimated 75,000 to 100,000 people in the United States, mostly of African or Hispanic descent. Abnormal hemoglobin（血红蛋白）, the protein that enables red blood cells to carry oxygen, causes sickle cells to acquire their crescent shape and rigidity. That elongated shape and inability to bend were thought to be the reason sickle cells caused blockages in capillaries.   But while sickle-shaped cells are the hallmark of the disease, they're not the only type of red blood cell present in people with the condition. Research from the 1980s found that there are actually four types of sickle red blood cells, and not all of them are rigid and sickle-shaped. One cell type, the SS2 cell, retains the round shape and the soft malleability（顺从，展延性） of normal red blood cells.   "They look like healthy cells," Karniadakis said, "except they're sticky."   The SS2 cells have receptors on their membranes that cause them to adhere to the walls of blood vessels. Sickle-shaped cells have those same sticky proteins, but Karniadakis's model showed that the SS2 cells are much more likely to get stuck. "Because [SS2 cells] are deformable, they have a larger contact area with the vessel wall, and so they stick better," Karniadakis said. 使用功能强大的计算机模型显示，来自布朗大学的研究人员第一次，如何将不同类型的红血细胞相互作用，从而导致镰状细胞危象，一个危险的血流量阻塞导致在人们灼热的疼痛和组织损伤毛细血管（毛细血管）镰状细胞疾病。模型显示，刚性的，月牙形的红血细胞，镰状细胞病的特点，不会造成堵塞自己。相反，柔软，可变形的红血细胞被称为SS2细胞启动过程中，坚持毛细血管壁。刚性镰刀形细胞，然后叠起来背后SS2s，如交通落后的汽车残骸。   这项研究结果发表在国家科学院的法律程序，可以提供一种方法来评估药物治疗旨在减轻或预防镰状细胞危象，也被称为血管闭塞。   “乔治Karniadakis，应用数学教授在布朗和研究的高级作者，说：”这是第一次研究，以找出一个特定的生物物理机制，通过血管闭塞发生。“这是一个令人惊讶的结果，因为共同的智慧是，这是仅有的镰状细胞，阻断了毛细管。”   镰状细胞病是一种遗传性疾病，影响估计75,000至100,000人，在美国，大部分非洲或拉美裔血统。异常血红蛋白（血红蛋白）的蛋白质，使红血细胞携带氧气，导致镰状细胞获得的月牙形状和刚性。即细长的形状和镰状细胞造成毛细管堵塞的原因被认为是不能弯曲。   不过，虽然镰状细胞疾病的标志，他们不是唯一的类型的红血细胞中存在的条件的人。从20世纪80年代的研究发现实际上有四种类型的镰状红血细胞，并不是所有的人是刚性的，镰刀形。一种细胞类型，的SS2细胞，保留圆形的和软的可锻性（顺从，展延性）的正常红细胞。   “它们看起来像健康细胞，”Karniadakis说，“除了他们粘”。   SS2细胞上的受体，导致他们坚持血管壁膜。镰刀形细胞有同样的粘蛋白，但Karniadakis的模型表明SS2细胞更容易被卡住。“因为SS2细胞变形，他们有更大的接触面积与血管壁，使他们更好地坚持，”Karniadakis说。 “成千上万人疯狂下载。。。。。。 更多价值连城的绝密英语学习资料， 洛基内部秘密英语，技巧，策略 请在 网上 申请报名” 洛基国际英语 竭诚为您服务