大閱讀1-73篇大閱讀-8_W

1、微信公眾號：醫(yī)學(xué)博士英語南京醫(yī)科大學(xué)小白老師大閱讀第 8 天 小白老師醫(yī)學(xué)考博英語網(wǎng)絡(luò)課程The biter bitKILLING mosquitoes of the genus Anopheles, the sort that transmit malaria, is aserious businessso serious that some doctors would like to do it by using people asbait. Their idea is to dose those in malarious areas with a drug called ivermect

2、in. Thiswill not protect the dosees directly, for it does not act on the parasite that causes thedisease. But it may protect them indirectly, by making their blood poisonousto Anopheles. Mosquitoes do not tend to fly far from the place they hatch, andexperiments suggest that if most of a villages in

3、habitants were to take ivermectinthey could collectively do serious damage to the local Anopheles population. Thatwould substantially reduce the number of cases of malaria in an area.Whether this isis debated. Ivermectin is used routinely to treat filariasis,river blindness, scabies and several othe

4、r diseases. But drugging healthy people isgenerally frowned on. At the moment, though, there is a more practical objection.Ivermectin does not hang around in the body long enough to make a concertedanti-mosquito campaign that relies on it look like a realistic proposition. And it is thisthat Robert

5、Langer of the Massachusetts Institute of Technology and GiovanniTraverso at Brigham and Womens Hospital, in Boston, hope to change. As theyreport in Science Translational Medicine, they think they have devised a means tokeep ivermectin concentrations in the blood at mosquito-killing levels for far l

6、ongerthan has previously been possible.1 / 4ethical微信公眾號：醫(yī)學(xué)博士英語南京醫(yī)科大學(xué)小白老師The starting point for their device is a material called poly E-caprolactone (PCL).Theythis and blended it with powdered ivermectin. Then they tested theresulting composite in an acidic solution intended to mimic conditions fou

7、nd in thehuman stomach, to see how well it protected the drug, and also the rate at whichivermectin migrated out of it. They found that the PCL did indeed protect theivermectin from the acid. It also let the drug diffuse out steadily over the course of14 days.Encouraged by this finding, the two rese

8、archers pondered how to arrange for ablock of ivermectin-doped PCL to stay in the stomach that long, rather than passingthrough to the intestine and thence, ultimately, to the outside world. Their solutionwas a star-shaped structure 4cm across (see picture) with a flexible polyurethanecore and arms

9、made of ivermectin-laden PCL.For delivery, this is folded up inside acapsule, so that it can beswallowed. Once it arrives in the stomach, the gelatine is rapidly digested and thestar unfolds into something large enough to avoid being expelled into the intestine,but insubstantial enough not to obstru

10、ct the passage of semi-digested food throughthe alimentary canal. After careful experiment, the researchers came up with anivermectin-PCL mixture that disintegrates as it gives up its payload. Once the arms,which are made of this mixture, have dissolved, the core is small enough to pass tothe intest

11、ine and out of the body.Laboratory tests suggested this arrangement would work, so the researcherstried it out on animalsspecifically, a dozen Yorkshire pigs. These are a common2 / 4gelatinemelted微信公眾號：醫(yī)學(xué)博士英語南京醫(yī)科大學(xué)小白老師breed, and the passages between their stomachs and their intestines are similar in

12、size to those of people.Using X-rays, they monitored the stars movements through the pigs guts. Theyalso sampled the animals blood, to work out how much ivermectin was getting intoit. As they had hoped, the stars were able to release mosquito-killing doses ofivermectin for up to two weeks. And, as i

13、ntended, when their payloads wereexpended they collapsed and passed safely through the remainder of thesystem without causing any obvious ill effects.Dr Langer and Dr Traverso hope to start human trials next year. But they alsowonder if they have come up with something that might be more widely depl

14、oyed.Taking repeated doses of any drug to keep its level up is a. If the stars could beimpregnated with other drugs, then things now requiring daily or more frequentdoses might be delivered on a one-horse-pill-per-fortnight basis. That would almostcertainly improve compliance.Which, if any, other dr

15、ugs might be delivered in this way remains to be seen. But,even if the stars work only for ivermectin (assuming they do), they will still be auseful addition to the armoury being deployed against malaria. And that, alone,could save many lives a year.1. ethical 英 ekl 美 kladj.學(xué)的； 道德的，的； 憑處方出售的； n.憑醫(yī)師處方出售的藥品 2. melt 英 melt 美 mltvi.熔化，溶解； 逐漸融合； 逐漸消失； 感動，軟化，感情上變得