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(huì)說吸血蝙蝠是個(gè)討厭的東西。而那些讀現(xiàn)代醫(yī)學(xué)雜志的人也許不同意這樣的觀點(diǎn)，他們認(rèn)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(shí)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(jīng)常流口水，因?yàn)橥僖菏撬鼈冿嬍沉?xí)慣中的必不可少的一部分。
當(dāng)吸血蝙蝠纏在，比如一直公牛身上時(shí)，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?jiǎng)﹣韺?shí)現(xiàn)的。盡管你會(huì)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(fēng)。
中風(fēng)是由于血液凝結(jié)成塊阻礙其流動(dòng)，從而導(dǎo)致大腦部分缺氧。醫(yī)生們已經(jīng)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(xiǎn)的副作用，甚至?xí)p傷腦細(xì)胞。
有更好的主意嗎?澳大利亞生物化學(xué)家，Robert Medcalf對(duì)蝙蝠進(jìn)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(xiàn)在正在患有中風(fēng)病人身上測(cè)試，結(jié)果將于一年內(nèi)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。
