BACKGROUND: Stem cells are the potentially immortal cells capable of self-renewal, which are essential to the mystery of human development and aging, and are also the core of research for regenerative medicine. OBJECTIVE: To summarize the biological characteristics of embryonic stem cells, adult stem cells and induced pluripotent stem cells, to review the clinical and commercial applications in stem cell therapy and drug screening, and to analyze the problems and prospects in stem cell industry. METHODS: We searched relevant articles about stem cell models in PubMed and CNKI databases during 1995 to 2017 on internet, and took"stem cells, embryonic stem cells, adult stem cells, induced pluripotent stem cells, stem cell therapy, drug screening" as the keywords in English and Chinese, respectively. RESULTS AND CONCLUSION: According to the origin, stem cell models are divided into three types: embryonic stem cells, adult stem cells and induced pluripotent stem cells. Different types of stem cells have their unique biological advantages. Embryonic stem cells can generate all somatic cell types, but the application is limited by ethical disputes. As for adult stem cells, there are the most extensive and in-depth, studies as the well as the most prevalent and mature applications. Induced pluripotent stem cells have similar characteristics as embryonic stem cells, and furthermore their use avoids source restriction, moral and ethical controversies, bringing new opportunities for stem cell application. Stem cell-based cell therapy has shown successful achievement. There have been a few commercial products about adult stem cells-based cell therapy; in the meanwhile both embryonic stem cells and induced pluripotent stem cells are making their way into clinical trials. In addition, pluripotent stem cells hold great promise for the specific drug screening because they enable scientists to establish a variety of cell and disease models in vitro.

OBJECTIVETo study the potential risk factors for severe acute respiratory syndromes (SARS)-related deaths in Beijing.

METHODSEpidemiological data were collected among the confirmed SARS patients officially reported by Beijing Centers for Disease Control and Prevention (BCDC), and information was also supplemented by a follow-up case survey. Chi-square test and multivariate stepwise logistic regression analysis were performed.

RESULTSOld age (over 60 years) was found to be significantly associated with SARS-related deaths in the univariate analysis. Also, history of contacting SARS patients within 2 weeks prior to the onset of illness, health occupation, and inferior hospital ranking as well as longer interval of clinic consulting (longer than 1 day) were the risk factors for SARS-related deaths. Multivariate stepwise logistic regression analysis found four risk factors for SARS-related deaths.

CONCLUSIONOld age (over 60 years) is the major risk factor for SARS-related deaths. Moreover, hospital health workers, the designated hospitals for SARS clinical services and the interval of consulting doctors (less than 1 day) are protective factors for surviving from SARS.

Adolescent ; Adult ; Age Factors ; Aged ; Aged, 80 and over ; Child ; Child, Preschool ; China ; epidemiology ; Humans ; Infant ; Middle Aged ; Multivariate Analysis ; Risk Factors ; Severe Acute Respiratory Syndrome ; epidemiology ; mortality

OBJECTIVETo describe the epidemiologic features of an outbreak of severe acute respiratory syndrome (SARS) in urban and suburb areas in Beijing and to explore their differences between these two areas.

METHODSData of SARS cases were collected from daily notification of China Ministry of Health and a database of infectious diseases was established by the Beijing Municipal Center for Disease Prevention and Control (BCDC). All the data were put into dataset files by Microsoft Excel-2000 and analyzed with SPSS version 10.0 software.

RESULTSThe respective urban incidence and mortality rate were 29.06 and 2.21 per 100,000, while the case fatality rate was 7.62%. In contrast, the respective suburb incidence and mortality rate were 10.61 and 0.78 per 100,000, and the case fatality rate was 7.32%. No significant differences were found in demographic characteristics between the urban and suburb areas.

CONCLUSIONBeijing urban area suffered a more serious SARS epidemic than the suburb area in 2003.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Child ; Child, Preschool ; China ; epidemiology ; Cities ; Female ; Health Occupations ; Humans ; Incidence ; Infant ; Male ; Middle Aged ; Severe Acute Respiratory Syndrome ; epidemiology ; mortality ; Suburban Population ; Urban Population

BACKGROUND: Adipose-derived mesenchymal stem cells (ADSCs) that are manufactured in good manufacturing practice (GMP) clean rooms should be made into stem cell preparations before administration. Low-temperature preparation has many advantages over cryopreservation preparation; however, little is reported on the effect of short-term low-temperature storage on the biological characteristics of stem cells. OBJECTIVE: To evaluate the effect of 24-hour low-temperature storage using multiple electrolytes containing 5% human serum albumin on the biological characteristics of ADSCs.METHODS: ADSCs at passages 3-6 at a concentration of 5×109/L were suspended in multiple electrolytes containing 5% human serum albumin. Cell suspension was transferred into cryogenic vials, and then these vials were placed in a cold chain shipping box for 2-8 ℃ low-temperature storage for 24 hours. Cell morphology, adhesion ability, cell viability, cell diameters and cell immunophenotyping before and after the storage were observed. RESULTS AND CONCLUSION: (1) After low-temperature storage of ADSCs for 24 hours, the number of dead cells increased. Although cell viability decreased significantly, it was still higher than 80%. Cell diameters of living cells increased significantly. (2) After low-temperature storage of ADSCs for 24 hours, few cells which were circle-shaped lost adhesion ability, and most cells could adherently grow, with the spindle-shaped morphology similar to the cells before preservation. (3) After low-temperature storage of ADSCs for 24 hours, HLA-DR, CD34 and CD45 were negatively expressed with a positive rate lower than 2%; CD29, CD73 and CD105 were positively expressed with a positive rate higher than 95%. However, the cell cluster was clearly divided into two parts after the preservation. Cells with enlarged diameters moved right in the FSC/SSC dot-plot. These results show that low-temperature preparation storage has no significant effect on the stemness of ADSCs, such as adhesion ability, cell viability and cell immunophenotype.

OBJECTIVETo describe the specific features of the contact history of probable cases of severe acute respiratory syndrome (SARS) in Beijing.

METHODSData of SARS cases notified from the Beijing Municipal Center for Disease Control and Prevention (BCDC) and supplemented by other channels were collected. All the data were analyzed by descriptive epidemiology.

RESULTS(1) The number of probable cases with contact history was significantly higher than the excluded cases. (2) The proportion of probable cases with contact history descended with epidemic development, but this situation did not occur in health care workers (HCWs). (3) The fatality rate of probable cases with contact history was significantly higher than the cases without contact history (OR = 1.489). (4) The proportion of probable cases with contact history was 85.86% among health care workers, which was significantly higher than that of non-health care workers (85.86% v.s. 56.44%, OR=4.69).

CONCLUSIONS(1) The susceptible persons with contact history may not get infected, and the contact history is just a sufficient condition of infecting SARS; (2) There are 3 conceivable reasons for the descending trend of the proportion in probable cases with contact history; (3) The contact history is one of the risk factors of the death of SARS cases; (4) The risk of contacting with SARS among health care workers is approximately 5 times higher than that of non-HCWs.

China ; Contact Tracing ; Data Interpretation, Statistical ; Disease Outbreaks ; Health Personnel ; Humans ; Medical History Taking ; Occupational Exposure ; Risk Factors ; Severe Acute Respiratory Syndrome ; epidemiology ; prevention & control ; transmission

Objective To treat simple malocclusions preliminarily using Chinese-made invisible orthodontic aligners and discuss the indications, problems existed and future development. Methods Forty-one cases with different malocclusions were selected, including crowding, spaces and spaces due to periodontal problems. Invisible aligners were made and worn by patients and they were changed every 2-3 weeks. Results Acceptable treatment results were obtained in all cases, with nice alignments and good overbite and overjet. Treatment time ranged from 6-25 months. Conclusions Indications of this technique were still limited and the technique needed to be further developed in the future.

OBJECTIVETo describe the case fatality rate of SARS in Beijing.

METHODSData of SARS cases notified from Beijing Center for Disease Control and Prevention (BCDC) and supplemented by other channels were collected. The data were analyzed by rate calculation.

RESULTSThe case fatality rate of SARS in Beijing was 7.66%, and had an ascending trend while the age of cases was getting older, and a descending trend while the epidemic development. The case fatality rate in Beijing was lower than that in other main epidemic countries or regions.

CONCLUSIONSThe risk of death increases with the increment of age of SARS patients. Beijing is successful in controlling and treating SARS.

Adolescent ; Adult ; Age Factors ; Aged ; Aged, 80 and over ; Child ; Child, Preschool ; China ; epidemiology ; Female ; Humans ; Infant ; Infant, Newborn ; Male ; Middle Aged ; Occupations ; Severe Acute Respiratory Syndrome ; mortality

OBJECTIVETo summarize lessons learned from an outbreak of severe acute respiratory syndrome (SARS) in China during the spring of 2004.

METHODSData of SARS cases were officially reported by Beijing Municipal Center for Disease Control and Prevention (BCDC) and Anhui Provincial Center for Disease Control and Prevention (APCDC) and results of epidemiological investigations were collected and analyzed.

RESULTSThree generations of 11 cases of SARS were identified during the outbreak. Initial two cases were most likely to be infected in Diarrhea Virus Laboratory of National Institute of Virology, China Centers for Disease Control and Prevention and main mode of transmission was direct contact with SARS patients. Delay in detecting initial case resulted in spread of the illness at hospitals and communities with two generations of secondary cases.

CONCLUSIONSSARS outbreak in 2004 has yielded following lessons for public health globally. (1) Lab bio-safety programs should be made and should be strictly abided by. Studies in highly pathogenic viruses such as SARS coronavirus should be utmost cautious. (2) Management systems of occupational exposure to virus and disease surveillance need to be strengthened to take all risk factors into account so as to detect potential patients with infectious disease as early as possible.

China ; epidemiology ; Disease Outbreaks ; Female ; Humans ; Male ; Occupational Exposure ; prevention & control ; Occupational Health ; Retrospective Studies ; Severe Acute Respiratory Syndrome ; epidemiology ; prevention & control ; transmission

Objective To evaluate the effects of small interfering RNA(siRNA)against Ki67 gene on the proliferation and apoptosis of human renal carcinoma cell line 786-0 cells.Methods The human renal carcinoma 786-0 cells were treated with Ki67-siRNA(100 nmol/L).The mRNA expression of Ki67 was detected by RT-PCR.The protein expression of Ki67 was detected by Western blot and immunohisto- chemical technique,respectively.The proliferation of 786-0 cells was detected by MTT assay.The apoptosis of 786-0 cells was detected by TUNEL assay.Results RT-PCR and Western blot analysis showed that the Ki67 mRNA and Ki67 protein expression levels of the 786-0 cells treated with Ki67-siRNA were(37.6?1.9)% and(46.4?0.9)% ,respectively,which were significantly lower than those of controls [(97.3?0.9)% and(95.3?0.9)%,P＜0.01],The Ki67 positive expression rate of 786-0 cells treated with Ki67-siRNA by immunohistochemical technique was 52.5?2.3,which was significantly lower than that of controls(114.5?4.9 ,P＜0.01).The proliferation-inhibiting rate and apoptosis rate of the 786-0 cells trea- ted with Ki67-siRNA were( 63.6?1.6)% and(41.7?0.6)% ,respectively,which were significantly higher than those of controls [(2.8?0.2)% and(10.3?1.4)%,P＜0.01].Conclusions siRNA against Ki67 gene can inhibit the proliferation and induce the apoptosis by blocking Ki67 expression of hu- man renal carcinoma 786-0 cells.The inhibition of Ki67 expression by siRNA may be a promising approach in gene therapy for renal cancer.

Objective To evaluate the long-term immunogencity and effectiveness of live attenuated hepatitis A (HA) vaccine (H2 strain) after one dose injection, through a 15 years' follow up observation. Methods A total of 220 children with negative anti-HAV antibody (aged 1-3 y)were involved and followed up in Jiaojiang district, Taizhou city, Zhejiang province. Indicators would include seroconversion and geometric meantiter(GMT) levels after inoculation the vaccine with single dose at 2 m, 12 m, 6 years, 10 years and 15 years. Epidemiological observation was carried out within the 15 years to evaluate the relationship between vaccine coverage, the incidence of HA and the overall effectiveness. In the studied population, serum was tested by ELISA(calibrated by WHO international reference) and ABBOTT Axsym HAVAB mEIA. Results Seroconversion rates were found to be 98.6% and 81.3% after 2 months and 15 years of inoculation and slowly decreased. GMT level was 128 mIU/ml after 15 years, significantly higher than the required protective level of 20 mIU/ml,recommended by WHO experts. Effectiveness through the 15-year follow up program showed a significant correlation between vaccine coverage and incidence of HA in 1-15 years aged group (Kendall-Rank test, t =-0.931, P＜0.01). There was no HA case seen among the observed accumulated 236 413 person-year vaccines, compared to 4 HA cases discovered in the 27 206 personyear of the non-vaccinees. The overall protective rate reached 100%. Through a mass vaccination program on children, the whole population established an immune-defence to enable the incidence of HA decreased by 96.7%. Conclusion The long-term immunogencity and effectiveness of live attenuated hepatitis A vaccine (H2 strain) after one dose injection could last as long as 15 years.