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1、对人体细胞和微生物数量的改进估计RonSender1.OriginofprevalentclaimsintheliteratureonthenumberofbacterialcellsInhumans为什么大家会普遍认为肠道微生物数量是人体细胞的十倍，本文作者对文献进行了追溯，结果显示1977年Savage,annu,Rev.Microbiol引用超过一千。而它的计算基础是胃肠道容积为1L，肠道微生物浓度为1011/g.2.Distributionofbacteriaindifferenthumano
2、rgans不同部位的微生物数量相差很大，由上表可知，人体微生物约90%都集中在结肠。所以作者统计了不同文献的结肠微生物浓度，平均值为0.92*1011/g.3.Concentrationofbacteriainthecolon4.Thenumberofhumancellsina“standard”adultmaleAmass-basedorder-of-magnitudeestimateforthisnumberassumesa102kgman,whichisdividedbythemassofa“r
3、epresentative”mammalian,cell10-12-10-11kg(assumingcellvolumesof1,000-10,000µm3,spectively),thusarrivingat1013-1014cells.OnestudyusedaDNA-centeredmethod(Baserga,1985).Themethodbeginsbyestimatingthenumberofcellsinthebodyofa25gmousebydividingthetotalamount
4、ofDNA(statedtobe20mg)bytheDNAcontentofonediploidmousecell(6·10-12gDNApercell)toget≈3·109cellsina25gmouse.Thenextrapolatefrommousetohumanbyusingtheratioofmassestoget≈1013cellsinthehumanbody.ThismethodexcludescellsthatdonotcontainDNA,suchasredbloodcellsan
5、dplatelets.Summingoveratotalof56cellcategories(Bianconietal.,2013)resultedinanoverallestimateof3.7·1013humancellsinthebody(SD0.8·1013,i.e.CVof22%)5.UpdatedinventoryofhumancellsinthebodyWefocusonthesixcelltypesthatwererecentlyidentified(Bianconietal.,201
6、3)tocomprise97%ofthehumancellcount:redbloodcellaccountingfor70%),glialcells(8%),endothelialcells(7%),dermafibroblasts(5%),platelets(4%)andbonemarrowcells(2%).Theother50celltypesaccountfortheremaining3%.5.UpdatedinventoryofhumancellsinthebodyRedbloodcell
7、s:(Boer,1984;FeldschuhandEnson,1977;Nadleretal.,1962;Snyderetal.,1975)4.9L(Ambayyaetal.,2014;Dosooetal.,2012;Nordinetal.,2004;Pekelharingetal.,2010;VolkmerandHeinemann,2011;Wakemanetal.,2007)5.0·1012cells/L(SEM1.2%,CV7%)(SEM1.6%,CV9%)Thisledtoatotalof2.
8、5·1013redbloodcells(SEM2%,CV12%)Thisissimilartotheearlierreportof2.6·1013cells(Bianconietal.,2013).5.Updatedinventoryofhumancellsinthebodyglialcells:Thenumberofglialcellswaspreviouslyreportedas3·1012(Bianconietal.,2013)estimateis
