更新时间：2016-10-09 来源：网络 投诉删除
医学英语论文是医学期刊的常见的文体。根据英国TheLancet杂志和香港Hong Kong Medical Journal上所登载的论文以及国外其它期刊所刊登的文章来分析，大体包括以下几个方面内容:标题、摘要、引言、方法、结果、讨论、致谢、参考文献。关于英语标题和摘要的写作格式在本刊2003年第4期上已经论述。现就论文的引言、方法、结果、讨论、致谢和参考文献做一详细论述，以飨读者。
The feasibility of ultrasonography for diagnosis of fetal cardiacabnormality was recognised in the early 1980s，and cardiac scanningis gradually being incorporated into fetal screening protocols.Theeffect of the screening process on the incidence and types ofcongenital heartdisease atterm has been difficultto ascertain becausemany pregnant women and infants travel great distances to specialistcentres which are farfrom their health authority.For a single centre，the geographical area from which its fetal referrals arrive is generallynot the same as the area attracting postnatal referrals，and the numberof births that each serves is impossible to define.The BritishPaediatric Cardiac Association(BPCA)undertook a nationalcollaborative study of fetal cardiac screening.The aim was to assessthe effect of fetal diagnosis of congenital heart disease on the patternof serious congenital heart disease at term.
该部分可依据所研究的对象或使用的材料和采用的方法，也可分别称之为:对象与方法(Subjects and methods or Patients and methods)，材料与方法(Materials and methods)。方法部分实际上是论文的主体，它是对论文的内容和采用的方法作出详细的论述。具体的顺序为:首先是所使用的材料或研究的对象，其次是程序安排，最后是结果计算或统计方法。方法部分一般为回顾性叙述，在时态上多采用一般过去时，偶尔也有用过去完成时。不过，假若叙述的是定义，理论，图表内容及数值，属于客观现象，故可采用一般现在时。举例:
Patients and methods
The Information and Statistics Department of the Scottish Homeand Health Department collected data on the demographics andlaboratory results of all possible outbreak cases.We collected clinicaldata by reviewing the case notes of all cases admitted to hospital inthe Lanarkshire area.
All confirmed or probable cases ofEscherilchia coli(E coli)0157 infection，identified in the Lanarkshire area during the outbreakperiod，were included in the assessment and analysis.Confirmedcaseswere those in whom the outbreak strain ofE coliO157 wasisolated from stool samples.If stool cultureswere negative atthe locallaboratories，specimens were sent to Scotland'sE colireferencelaboratory in Aberdeen，for the more sensitive isolation method ofimmunomagnetic separation.Probable cases were those with bloodydiarrhoea or haemolytic uraemic syndrome(HUS)/thromboticthrombocytopenic purpura(TTP)，an association with food sourcesimplicated in the outbreak，noE coliO157 isolated，and no otherorganism isolated.Adults were defined as patients 15 years of age orolder.
To allow standardisation of diagnosis in the face of a hugeclinical workload，a case definition for HUS and TTP was developedat the beginning of the outbreak.HUS was defined as evidence ofred-cell haemolysis(red-cell fragmentation on blood film and lactatedehydrogenase>1.5 times the upper limitof normal[our laboratory 0～480 IU/L])plus thrombocytopenia(platelets<150×109/L)with rising urea and creatinine concentrations.All three criteria hadto be met before the diagnosis could be made，but not necessarily onthe same blood sample.A diagnosis of TTPwas given to patientswhomet these laboratory criteria and developed new neurologicalsymptoms and signs.One patient was included as having developedHUS despite a minimum platelet count of 228×109/L(on death).
He had bloody diarrhoea，an association with an implicated foodsource，acute renal failure，the criteria for red-cell haemolysis，and afalling platelet count.
In the assessment of premorbid illness，medical historiesincluded as relevant were ischaemic heart disease，cardiac failure，hypertention，cerebrovascular disease，renal disease，diabetes，andimmunosuppression.Pulmonary oedemawas diagnosed on clinical andradiological evidence.
TPE was performed at three centres with three Cobe SpectraApheresis Systems(Cobe Laboratories Ltd，Gloucester，UK)and aBaxter Fenwal CS-3000 Plus Cell Separator(Baxter Healthcare，Newberry，UK).Plasma was exchanged with 2.0～2.4 Lfresh frozenplasma or cryosupernatant in refractory patients.The anticoagulantused was ACD-A.A combination of central and peripheral venousaccess was used.Intravenous hydrocortisone was given with eachexchange.Intravenous prostacyclin was also given to cases receivingTPE，at doses between 40 mg/h and 200 mg/h，where tolerated.Datawere analysed by means of SPSS(version 7.5).
There were 262 cases ofE coliO157 infection in theLanarkshire area:200 confirmed cases and 62 probable cases.Themedian age of all affected was 53 years，but there were highernumbers at the extremes of age.47%(124/262)of infectedindividualswere over 55 years of age.13(5%)people died.In 10cases death was associated with the systemic complications ofE coliO157 infection.
28(11%)of the Lanarkshire cases ofE coliO157 met thediagnostic criteria forHUS/TTP.Casesmet the criteria forHUS/TTPa median of 7 days(range 4～15)after the onset of gastrointestinalsymptoms.A further eight cases had evidence of thromboticmicroangiopathy but did not meet the criteria for HUS/TTP and werenot eligible for TPE.22(79%)cases with HUS/TTP were adultsand six(21%)were children.The median age of adults whodeveloped HUS/TTP was 71 years and the median age of children 6years.The demographics，clinical features，treatment，laboratoryresults，and outcome of the adult cases with HUS/TTP are shown intable 1.Blood results are taken from the day that the diagnosticcriteria for HUS/TTP were met，before TPE in cases so treated.
The mortality rate in adults with HUS/TTP was 45%(ten of22).Seven of 12 cases aged over 70 years and three of ten aged 70years or less died.There were no deaths in children.Necropsiesweredone for all cases who died.Causes of death in patients with HUS/TTPwere acute renal failure secondary to HUS(two cases)，cardiacarrest(two cases)，intracerebral haemorrhage，cerebral infarction，acute myocardial infarction，multiple organ failure，hepatorenalsyndrome secondary to macronodular cirrhosis and septic shock.
TPE was used in 16 of the 22 adultpatientswithHUS/TTP.Forpatients treated with TPE later received haemodialysis，because ofdeteriorating renal function.Patients who did not receive TPE wereeither too unwell to tolerate the procedure or died before TPE couldbe carried out.
In all 16 cases treated with TPE，the first exchange was firstdone within 24h of the criteria for HUS/TTP being met.Theminimum number of changes was one，the maximum 16，and themedian six.Patients underwent a total of 107 procedures，and 1100units of fresh frozen plasmawere used.Two patients proved refractoryto treatment with fresh frozen plasma，after five and six exchanges，but were successfully treated by additional TPE with cryosupernatantas the exchange fluid.Five of the 16(31%)TPE-treated patientsdied，four of eight aged over 70 years and one of eight aged 70 yearsor less.Premorbid illness，neurological features，treatment withciprofloxacin or prostacyclin，and the laboratory severity of HUS/TTPwere not associated with death，although the number of caseswas toosmall to allow statistical conclusion.
The most frequent complication associated with plasma exchangewas pulmonary oedema，which was diagnosed on clinical andradiological grounds in 11 cases.Pulmonary oedema was not confinedto patients undergoing TPE;three of six HUS/TTP cases not treatedwith TPE had pulmonary oedema.Hypocalcaemia(calcium<2.12mmol/L)occurred in 15 of the 16 patients treated with TPE.
Although severe(minimum serum calcium 1.32mmol/L)in manycases，intravenous magnesium was given when appropriate and noclinical effects were observed.Other complications associated withTPEwere line infectionwithmeticillin-resistantStaphylococcus aureusand extravasation infusion.
HUS/TTP used to be a rare disease in adults，with an estimatedfrequency of one case per million per year.In 50%of cases it wasassociated with pregnancy，malignant hypertension，HIV infection，cancer，or chemotherapy，and the remainderof caseswere familial orof unknown cause.In 1986 the first association of HUS/TTP withEcoliO157 infection was made and the incidence of the disorder hassince continued to rise in parallel with the global rise inE coliO157infections.After exposure toE coliO157，between 3%and 7%ofall patients progress to overt HUS/TTP.The incidence of HUS/TTPis highest in children and elderly people.
The course and prognosis of HUS/TTP differ substantiallybetween adults and children.Children with HUS develop acute renalfailure precipitately and the treatment of choice is dialysis，which isinitiated when the child becomes oliguric.Most children respond todialysis，and mortality rates of less than 5%are nowreported.In thecentral Scotland outbreak there were no deaths in children.Adultsseem to develop neurological or cardiovascular complications beforethe onset of oliguria.Neurological features are associated withincreased mortality，and neurological and cardiovascularcomplications of HUS/TTP were the most frequent causes of death inthe central Scotland outbreak.
Plasma exchange is an expensive(￡2500 per person treated inour hospital)and intensive procedure.Its effectiveness in thetreatment of HUS/TTP induced byE coliO157 needs to be showndefinitively in a multicentre，randomised controlled trial.However，for a disease with very high mortality and just one potentiallybeneficial treatment option，a trial thatwithholds this optionwould behard to justify.It would also be extremely difficult to organise sincecases ofE coliO157 occur sporadically.There will always be anunavoidable selection bias within such a trial，with patients who areexcluded from treatment because they have contraindications to TPEorwho die before treatment can be initiated.
If 5%of all cases ofEcoliO157 develop HUS/TTP，we wouldexpect about 40 adult cases of HUS/TTP per year in the UK(datafrom the Communicable Disease Surveillance Centre and ScottishCentre for Infection and Environmental Health).We suggest that anational register be established for adult cases of HUS/TTP，ascurrently operates for cases in children.This database would enablemonitoring of treatment and outcomes in adults，providing definitiveevidence of the effectiveness of TPEwithin about 5 years.
There is no evidence from our experience that TPE is harmful.
A national register of HUS/TTP secondary toE coliO157 coulddefine the role of TPE in the treatment of this serious disorder.
AcknowledgementsWe thank AK R Chaudhuri and W HWatson for their clinicalcontribution;the renal physicians and haematoligists at GlasgowRoyal Infirmary and Stobhill Hospital for clinical assistance in themanagement of cases;M Drummond for data collection;and theCentral ScotlandE coliO157 Research Group for the laboratorydatabase.