The severe acute respiratory syndrome (SARS) has been spreading in nearly 30 countries and regions worldwide recently. In response to its outbreak, many laboratories worldwide collaborated to identify the causative agent of SARS. A new type of coronavirus(named SARS CoV)has been isolated consequently, and the complete genomic sequences of the SARS CoV have been published. It is very important, at this stage, to deeply investigate the functional genome of SARS CoV with modern molecular techniques. As a new gene silencing method at RNA level, the recently established RNA interference will be a useful approach for the studies of SARS CoV genome.

Tropical medicine is defined by an association with geographic location,and it is a branch of medicine integrating preclinical medicine,clinical medicine and preventive medicine and investigating the diagnosis,treatment and prevention of diseases of tropical and subtropical zones.Military tropical medicine is a new interdiscipline based on tropical medicine and military medicine.With the improvement of health condition and the development of global economy,some tropical infectious diseases have been gradually controlled.However,factors such as increasingly frequent international communication and extreme changes in global climate induced by overproduction activity of human are leading to a redistribution of infectious diseases,which inevitably has impact on military strategies and tactics.This article reviews the past and prospect of military tropical medicine.

By studies of primary influencing factors in interferon ( IFN ) purification as well as affinity of IFN for different ligands, a purification system for leukocyte IFN from human umbilical cord blood was preliminarily established, and the properties of this IFN were studied.The established purification system includes two steps. The first step may be called "rough purification" using potassium thiocyanate (KCNS)-alcohol method. The second step "fine purification" using Blue Dextran-sepharose 4B(BDS) column affinity chromatography. The effects of different temperature, KCNS concentration, pH and the time(s) of salting out with KCNS on the activity, purity and recovery of the IFN were studied. Moreover, the affinity of the IFN for Blue Dextran and the chromatographic behavior of it on ConA-sepharose 4B column and BDS column were also observed.The experimental results showed that optimal conditions for precipitating the IFN from the crude IFN solution were to add KCNS to 0.5M, and then adjust pH to 4.0. The optimum pH values in separating out the IFN from acid alcohol-interferon were 5.5 to 7.2. The results between the salting out of once and twice by KCNS were not significantly different. Centrifugation with centrifuge maintaining lower temperature with cold alcohol might be used instead of refrigerated centifuge during purification. The IFN can be purified to about 106 international units per mg of protein with about 70% recovery on the first step of purification. On the second step of purification, the specific activity of IFN in the collecting fraction with maximum activity was increased up to about 107 international units per mg of protein and the recovery of activity was over 40%.Furthermore, the present findings indicated that the IFN from human umbilical cord blood was resistant to treatment with Sodium Dodeyl Sulfate(SDS), nucleolytic enzymes and pH 2.0; but sensitive to proteolytic enzymes. It was proved that the IFN had clearly species specificity. The determination of antiviral activity titer in SDS-PAGE gel slices documented that molecular weights of the IFN was about 18.3k to 24.3k. The IFN could be bound to Blue Dextran, but almost not to ConA. It indicates that IFN from human umbilical cord blood belongs in human IFN-? (Le) and is probably a glycoprotein that its carbohydrate moieties had hidden within IFN molecules.The present experiments may offer the possibility in purifying the IFN for clinical use and be helpful in revealing the essence of IFN from human umbilical cord blood. The purification method discribed in the paper will render some valuable reference to other types of IFN.

Epidemic diseases often occur following natural disasters,such as earthquakes.The most commonly seen epidemics after an earthquake include:enteric diseases(dysentery,typoid and paratypoid fever,cholera,hand-foot-mouth disease,hepatitis A,hepatitis E,etc),arthropod-borne infectious diseases(malaria,Kala-Azar,Japanese encephalitis,etc), zoonosis(plague,hemorrhagic fever with renal syndrome,anthrax,etc),soil and epidemic water transmitted diseases(tetanus, gas gangrene,leptospirosis,etc),respiratory diseases(measles,rubella,influenza,etc),food-borne diseases(food poisoning caused by bacteria or bacterial toxin).This article reviews the controlling principles and measures for major infectious pathogens and epidemic diseases after earthquake.

Presently, there are 3 problems in the study of human embryonic pluripotent stem cells: short of materials, complicacy of culture system and spontaneous differentiation. Both basic research and clinical application of human embryonic pluripotent stem cells were hindered by these 3 basic problems. New embryonic pluripotent stem cells should be established by combining nucleus transfer and plasma reprograming, and their possible mechanisms and key factors need further study. The culture system should be simplified and cell differentiation must be inhibited when pluripotent stem cell is cultured. When pluripotent stem cells are induced to differentiation, combination of several methods should be used to induce and select specific cell lineages, and the morphology and function of the target cell must be evaluated.

Hepatitis C virus cell entry is mediated by multiple factors,including various receptors and cellular factors that trigger virus uptake by the hepatocyte.Occludin is a newly identified essential co-receptor for HCV entry together with CD81,SR-B1 and CLDN1.CLDN1 and occludin highlight the importance of studying the effects of tight junction and cell polarization on HCV entry.Study on cell polarization and tight junction can help to discover new targets for HCV therapy,and therefore interfere the cell entry and cell-cell spread of HCV.This review summarizes the current knowledge of hepatocyte polarization,tight junction and its major integral proteins CLDN1 and occludin,polarized cell culture system and its relation with HCV entry.

The purification system described in this paper includes two steps. The first step may be called "rough purification" by using potassium thiocyanate (KCNS) -alcohol fractionation precipitation method. The second step is "fine purification" by using Blue Dextran-sepharose 4B (BDS) column affinity chromatography methodThe experimental results showed that the optimum condition for precipitating the interferon (IFN) from the crude IFN solution could be made by adding 0.5M KCNS, and then adjusting pH to 4.0. The optimum pH values in separating out the IFN from acid alcohol-interferon solution were 5.5 to 7.2. The results between the salting out once and twice by KCNS were not significantly different. Centrifugation with centrifuge maintaining lower temperature with cold alcohol could be used instead of refrigerated centrifuge during purification. The IFN can be purified to about 106 international units per mg of protein with about 70% recovery on the first step of purification. In the IFN yielded on the second step of purification, the maximum specific activity of IFN in the collecting fractions was increased up to about 107 international units per mg of protein with a recovery rate of over 40%.The present experiments may offer the possibility in purifying the IFN for clinical use. The Suggested purification method will also render some valuable reference to purify other types of IFN.

The Oct4,a POU transcription factor belongs to class Ⅴ of POU proteins, is expressed in mouse totipotent embryonic stem and germ cells. Oct4 plays a critical role in maintaining pluripotency of stem cell when it differentiates into a trophectoderm lineage at early stage of mouse embryo. Oct4 expression appears to be regulated by a positional effect as well as specific regulating elements of Oct4 such as proximal enhancer (PE) and distal enhancer (DE). Oct4 has both repression and activation effects in regulating transcription,and the activation has 3 models: distance dependent transactivation, conformational transactivation and Oct4 dimers dependent transactivation.

Objective To investigate pathogene city, replication and expression of hepatitis G virus (HGV) in rhesus monkey infected with HGV RNA genome or HGV RNA positive sera. Methods A full length cDNA clone of HGV was constructed. Rhesus monkey BY1 was inoculated intrahepatically with genomic RNA from this HGV clone resulted in viral replication. HGV RNA positive sera from BY1 were intravenously inoculated into rhesus monkeys BM1, and sera from BM1 were intravenously inoculated into BB1 in series. Sera were collected weekly or bi weekly and liver biopsies were performed regularly. RT PCR, in situ hybridization and immunological, serological, histological assays were carried out to study the infectivity and pathogenecity of HGV. Results The serological and pathological results indicated that all of the 3 rhesus monkeys developed HGV viremia and had slightly elevated alanine transaminase levels (up to 418 IU/ L) during the period of experiment. HGV RNA became positive at the 3 rd , 8 th and 3 rd week post inoculation in the animals BY1, BM1 and BB1 respectively, and existed up to 21 weeks. The histology, immunohistochemnistry, and in situ hybridization in the liver tissues of the inoculated animals also showed that there was a mild hepatitis with HGV E2 expression in cytoplasm of hepatocytes. RT PCR and quantitative PCR showed that HGV could replicate in liver.Conclusions The genomic RNA from HGV full length cDNA is infective to the rhesus monkeys resulting in mild hepatitis. Infection and the transmission of the HGV in the rhesus monkey provide an appropriate animal model for the study of HGV.

One hepatitis C virus(HCV) cDNA fragment, 534bp in length and designated as Q534, was obtained by means of PCR amplification with self-designed oligonucleotide primers. Q534 was doned into Hinc II site of pUC18 and the- recombinant plasmid pQ534 was then selected from the bacterial transformants. The sequence data indicated the Q534 was a cDNA fragment of HCV core gene, and located in HCV genome from positions 320 to 853 in correspondence with Chiron's prototype sequence. The homologies between Q534 and the prototype at the levels of nucleotides and amino adds were 90.9% and 97.6%, respectively. The homologies of Q534 with Japanese HCV-J and HCV-BK strains were 96.8% and 97.0% at the nucleotide level, and 98.2% and 98.8% at the amino add level. Compared with the corresponding sequences of other HCV isolates, this Chinese HCV isolate we obtained in the present study belongs to HCV group II .