英語聽力文摘 吸血蝙蝠能挽救生命？
蝙蝠的唾液
Anyone who reads gothic fiction will tell you that vampires are bad news. People who read modern medical journals, however, might disagree–in fact, they think vampires just might help save lives.
The kind of vampire I’m talking about is Desmodus rotundus, commonly known as the “vampire bat.” Yep, these little creatures are real; and even though they almost never turn into suave Romanian counts to drool over, they do drool a lot themselves. That’s because their saliva is an essential part of their dining habits.
When a vampire bat latches onto, say, a steer, it needs to keep the blood flowing from the puncture made by its teeth. That’s achieved by a natural anti-coagulant in the vampire bat’s saliva. Despite what you see in the movies, vampire bats almost never drink human blood. But people do suffer from other blood problems–a leading one being stroke.
Stroke is caused by a clotting in the blood which stops the flow and can starve areas of the brain of oxygen. Doctors have generally broken up clots with a compound called tPA. TPA works okay, but it has dangerous side effects, and can even hurt brain cells.
A better idea? Bring in the bats, says researcher Robert Medcalf, a biochemist from Australia. Vampire bat spit contains a different compound, DSPA, which does the good things tPA does with far fewer side-effects. DSPA is now being tried on patients who have suffered a stroke; the data should be in within a year. If it works, doctors might have found an unlikely friend–the vampire bat.
讀過哥特小說的人都會說吸血蝙蝠是個討厭的東西。而那些讀現代醫(yī)學雜志的人也許不同意這樣的觀點，他們認為吸血蝠能幫助拯救生命。
我說的是圓形葉口蝠，俗稱“吸血蝙蝠”。是的，這些小家伙是真實的，盡管它們幾乎沒有垂涎于溫雅的羅馬利亞人，但它們卻經常流口水，因為唾液是它們飲食習慣中的必不可少的一部分。
當吸血蝙蝠纏在，比如一直公牛身上時，必須保持血液從牙齒咬開的孔流過。這是通過蝙蝠唾液里一種天然的抗凝血劑來實現的。盡管你會在電影里看到，吸血蝙蝠幾乎從來不吸人的血。但人類患有其它血液疾病——最重要的就是中風。
中風是由于血液凝結成塊阻礙其流動，從而導致大腦部分缺氧。醫(yī)生們已經找到了分解血液凝塊的化合物，就是tPA。TPA很有效，但具有危險的副作用，甚至會損傷腦細胞。
有更好的主意嗎?澳大利亞生物化學家，Robert Medcalf對蝙蝠進行研究。吸血蝙蝠的唾液中含有一種不同的化合物，DSPA，它能夠幫助減少tPA引起的副作用，DSPA現在正在患有中風病人身上測試，結果將于一年內揭曉。如果有效的話，醫(yī)生們也許多一位意想不到的朋友——吸血蝙蝠。
