Rapid and High-throughput Identification of Recombinant Bacteria with Mass Spectrometry Assay

Objective To construct a rapid and high-throughput assay for identifying recombinant bacteria based on mass spectrometry. Methods Matrix assisted laser desorption ionization time-of-flight mass spectrometry （MALDI-TOF MS） techniques were used to identify 12 recombinant proteins （10 of Yersinia pestis, 1 of Campylobacter jejuni and 1 of Helicobacter pylori）. A classification model for the various phase of recombinant bacteria was established, optimized and validated, using MALDI-TOF MS-CIinProTools system. The differences in the peptide mass spectra were analyzed by using Biotyper and FIexAnalysis softwares. Results Models of GA, SNN, and QC were established. After optimizing the parameters, the GA recognition model showed good classification capabilities： RC=100%, mean CVA=98.7% （the CVA was 96.4% in phase 1, 100% in phase 2, 98.4% in phase 3, and 100% in phase 4, respectively） and PPV=95}. This model can be used to classify the bacteria and their recombinant, which only requires 3.7x103 cells for analysis. The total time needed is only 10 min from protein extraction to reporting the result for one sample. Furthermore, this assay can automatically detect and test 96 samples concurrently. A total of 48 specific peaks （9, 16, 9, and 14 for the four stages, respectively） was found in the various phase of recombinant bacteria. Conclusion MALDI-TOF MS can be used as a fast, accurate, and high-throughput method to identify recombinant bacteria, which provide a new ideas not only for recombinant bacteria but also for the identification of mutant strains and bioterrorism pathogens.

Assessing Heat-related Mortality Risks in Beijing,China

Objective To obtain the exposure-response relationship for temperature and mortality, and assess the risk of heat-related premature death. Methods A statistical model was developed using a Poisson generalized linear regression model with Beijing mortality and temperature data from October 1st, 2006 to September 30th, 2008. We calculated the exposure-response relationship for temperature and mortality in the central city, and inner suburban and outer suburban regions. Based on this relationship, a health risk model was used to assess the risk of heat-related premature death in the summer （June to August） of 2009. Results The population in the outer suburbs had the highest temperature-related mortality risk. People in the central city had a mid-range risk, while people in the inner suburbs had the lowest risk. Risk assessment predicted that the number of heat-related premature deaths in the summer of 2009 was 1581. The city areas of Chaoyang and Haidian districts had the highest number of premature deaths. The number of premature deaths in the southern areas of Beijing （Fangshan, Fengtai, Daxing, and Tongzhou districts） was in the mid-range. Conclusion Ambient temperature significantly affects human mortality in Beijing. People in the city and outer suburban area have a higher temperature-related mortality risk than people in the inner suburban area. This may be explained by a temperature-related vulnerability. Key words： Temperature; Mortality; Premature death; Health risk; Generalized linear regression model; Climate change

Severe Acute Respiratory Syndrome-Retrospect and Lessons of 2004 Outbreak in China

Objective To summarize lessons learned from an outbreak of severe acute respiratory syndrome （SARS） in China during the spring of 2004. Methods Data 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. Results Three 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, Conclusions SARS 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.