英语四级考试真题之阅读
英语四级考试真题之阅读1
Questions56to60arebasedonthefollowingpassage.
ScientistsatWashingtonUniversitySchoolofMedicineintheUSfoundhigherlevelsofproteinS1PR2(磷酸鞘氨醇受体蛋白)intestsonthebrainsoffemalemiceanddeadwomenwithMSthaninmaleequivalents.FourtimesmorewomenthanmenarecurrentlydiagnosedwithMultipleSclerosis(多发性硬化症).
Expertssaidthefindingwas”reallyinteresting”.MSaffectsthenervesinthebrainandspinalcord，whichcausesproblemswithmusclemovement，balanceandvision.Itisamajorcauseofdisability,andaffectsabout100，000peopleintheUK.AbnormalimmunecellsaRacknervecellsinthecentralNervoussysteminMSpatients.Thereiscurrentlynocure，A.thoughtherearetreatmentsthatcanhelpintheearlystagesofthedisease.
ResearchersinMissourilookedatrelapsingremitting(复发缓解型)MS，wherepeoplehavedistinctattacksofsymptomsthattllenfadeawayeitherpartiallyorcompletely.About85%ofallpeoplewithMShavethistype.Scientistsstudiedthebloodvesselsandbrainsofhealthymice，micewithMS，andmicewithoutthegeneforSlPR2，abloodvesselreceptorprotein，toseehowitaffectedMSseverity.TheyA.so100kedatthebraintissuesamplesof20peopleaftertheyhaddied.TheyfoundhighlevelsofS1PR2intheareasofthebraintypicallydamagedbyMSinbothmiceandpeople.TlleactivityofthegenecodingforS1PR2waspositivelycorrelatedwiththeseverityofthediseaseinmice.thestudysaid.
ScientistssaidSlPR2couldworkbyhelpingtomaketheblood-brainbarrier,inchargeofstoppingpotentiA.lyharmfulsubstancesfromenteringthebrainandspialfluid.morepermeable.Amorepermeablebarriercouldletattackingcells，whichcauseMS，intothecentralnervoussystem，thestudysaid.Thislink[betweenMSandSlPR2]iscompletelynew一ithasneverbeenfoundbefore.
DrEmmaGray,oftheMSSociety,said：”Wedon’tyetfullyunderstandwhyMSaffectsmorewomenthanmen,and