Ethosuzimide,whichwasdevelopedinthe1950s,iscommonlyusedtotr eatepilepsy,thoughitisnoknownpreciselyhowthedrugcontr olsconvulsions.Thereisnoanecdotalevidencethatithashadananti-aglngeffectinpeople.Thenextstep,Komfeldsays,istotestifthedrugshaveananti-agingeffectonanimallikefliesandmice。Verylittleisknownabouttheagingprocess.Fromgeneticanalysis,researchershavefoundthataninsulin-likesignalingsystemregulatesagingandlongevity.Agooddietcandelayagingandextendapersonlifespan.Butscientistsknowvirtuallynothingabouttheeffectofdrugsonaging.“It’sabigvoid,”Konfeldsaid。Inadditiontodelayingage-relateddegenerativechanges,thedrugsalsoincreasedneuromuscularactivty,suggestingalinkbetweentheneuromuscularsystemandtheagingprocess。
A.ButKomfeldsaidscientistswillnotknowabouttheapplicabilityofthedrugsinhumansuntilasimilarstudyisdoneonhumans.“What’sveryencouragingisthatthesedrugsweredevelopedtotr eathumans,andtheyarewellunderstood,becausethey’vebeenusedforalongtime,”hesaid。
B.Laterthescientistsdiscoveredthattworelatedanticonvulsantd rugsalsolengthenedthelivesoftheworms-inthecaseofonedrug,byalmost50percent.“Thiswasabigsurprisetouse,Komfeldsaid.”“Wedidn’tthinkanticonvulsantd rugshadanyparticularrelationshiptoaging.Thatconnectionwascompletelyunexpected.”
C.Roundwormsareapoorsubjectforexperiments,becausetheyarenotlikehumans,eventhoughtheirmoleculesaresimilar.Forexample,theyhavenobones,nordotheyshowemotions,makingitd ifficulttoknowhowexactlyhumansubjectswouldreacttothesedrugsinlargequantities.However,usingthewormsallowsexperimentstobeconductedquickly,becausetheydonotliveforlong。
D.“Somehowtheneuralactivityseemstoregulatetheagingofallofthebodytheskin,musculature,andreproductivetr act,”Kornfeldsaid.“Somehowthenervoussystemcoordinatestheprogressofallthesetissues,evidently,thoughthelifestages.Butwedon’tknowhowitd oesthat.”
E.Thediscoverymayalsoshedlightonthelittle-understoodagingprocess.Sincethedrugsactontheneuromuscularsystemsofbothhumansandworms,thefindingshintatalinkbetweenneuralactivityandaging。
F.Unlikevertebrates,thewormsareidealsubjectsforthestudyofagingbecauseoftheirshortlifespans,whichlastonlyacoupleofweeksinalaboratory.Thewormiswellknowningenetics,andtheworm’sgenomehasbeensequenced。
G.Useofthisdrughasbeenpermittedbylawsince1998andwideruseisnowexpectedasaresultofthestudies.“Wecanclearlylinkthisdrugwithhumanaging,butwestillneedtofindproof,saysKornfeldoptimistically.”
正确答案：A空前文字提到：“有理由相信这种实验结论对更高级的动物，如人类，也同样适用”。所以这一空应该继续谈到实验结果对人类究竟是不是适用的问题。选项A提到：“但是科学家们目前还不知道究竟对人类是不是适用，除非也在人类身上做相同的实验”。显然，选项A最合适。
