Objective To verify the feasibility and application value of an improved method for determination of urinary iodine by As3+-Ce4+ catalytic spectrophotometry.Methods Adults urine samples were collected,iodine calibration curves of 0-300 μg/L and 300-1200 μg/L were prepared,and urinary iodine was determined by the improved As3+-Ce4+ catalytic spectrophotometric method.Lyophilized human urinary iodine ingredient standards were used to validate linearity and range,limit of detection,precision and accuracy of this improved detection method.Results The linear range of the calibration curve was 0-300 μg/L,the detection limit was 1.8 μg/L,and the range of correlation coefficient was-0.9995--0.9997.When measuring urinary iodine at 40-80,100-149,200-280 μg/L,the relative standard deviations were 1.5％,0.8％ and 0.5％.When measuring urinary iodine at 40-80,100-149,150-180 μg/L,the average recoveries were 97.8％,99.8％ and 96.6％.Two given values of urinary iodine of national standard samples were (73.0± 9.0) and (206.0± 10.0)μg/L,and the results determined by this method were (75.5 + 0.9) and (207.5 ± 1.9)μg/L,and the relative deviation was 3.4％ and 0.7％,respectively,the results determined were all within the given value range.The linear range of the calibration curve was 300-1200 μg/L,the detection limit was 305.2 μg/L,the range of the correlation coefficient was-0.9996--0.9999.When measuring urinary iodine at 300-400,500-600 and 1000-1200μg/L,the relative standard deviations were 0.6％,1.0％ and 0.7％.When measuring urinary iodine at 300-499,500-599 and 600-700 μg/L,the average recoveries were 99.7％,99.2％ and 100.4％.Two given values of urinary iodine of national standard samples were (558.3 ± 3.5) and (884.8 ± 4.7)μg/L,the results determined by this method were (556.0 + 17.0) and (883.0 ± 28.0)μg/L,and the relative deviation was 0.4％ and 0.2％,respectively,the results were all within the given value range.Conclusions This method extends the detection range of iodine concentration,and improves precision and accuracy.This method greatly reduces the amount of arsenic used therefore reduces environmental pollution,which is suitable for promotion.

E.coli single-stranded DNA-binding protein (SSB) plays an important role in replication, recombination and repair of DNA and is thus crucial for the survival of the bacteria.We described a high expression and efficient purification scheme and kinetic assay of interaction with its substrate, single-stranded DNA (ssDNA). A ssb gene (537 bp) for encoding SSB was obtained by PCR amplification from E.coli K-12 genome. The expression vector of the fusion protein SSB was constructed by attaching ssb gene to pQE30. SSB fusion protein was expressed in M15 E.coli strain induced by IPTG. SDS-PAGE analysis revealed that the expected protein with a molecular weight 20.6kDa was soluble and amounted to about 30% of the total bacterial protein. SSB protein was purified by immobilized metal (Ni2+) chelation affinity chromatography and the purity was about 90%. The resulting SSB protein was a correctly folded tetramer analyzed by gel filtration. It could bind ssDNA with equilibrium dissociation constant (KD) of 4.79×10-7 mol/L as determined by surface plasmon resonance.

Objective To establish information management systems of drinking water defluoridation project in water-related endemic fluorosis areas and investigate the status of drinking water defluoridation project in Liaoning, provide the basis for the development of control measures. Methods Global positioning systems (GPS)and geographic information systems(GIS) were used in the study in August 2006 - July 2008. Water defluoridation projects of 1234 in 48 counties(cities, districts) in drinking water type of fluorosis areas were positioned. Latitude and longitude, water samples, water fluoride content were collected or tested. GIS was used to establish information management system of water defluoridation projects. Results We have established information management system for the facilities of decreasing water fluorine in drinking water type of endemic fluorosis regions in Liaoning. One thousand two hundred and thirty four defluoridation facilities distributed in east longitude between 39.39° - 43.37°,north latitude between 119.25° - 125.50°, and altitude between - 6.60 and 801.14 meter in 48 endemic fluorosis counties in 13 cities. Nine hundred and twenty seven facilities for decreasing fluorine were able to supply water regularly, accounting for 75.1% of investigated projects;29 facilities was .not yet completely rebuilt, accounting for 2.4%;278 facilities(supply water for 344 villages) were out of order or discarded for 22.5% of investigated projects.Water fluorine contents of 63 facilities were greater than 1.2 mg/L, accounting for 6.8% of investigation project.Facilities working regularly and water fluorine was in accord with hygienic standard for drinking water facilities were 70.0%. Conclusions The establishment of Liaoning province defluoridation project information management system in the whole province of drinking water type of fluorosis areas provides scientific basis for accurate decision-making on prevention and control of the disease.

Objective To establish TaqMan Real-Time PcR method for detection and identification of Neisseria meningitidis.Methods Seven sets of primers and FAM-labeled probes targeting different genes of Neisseria meningitidis were designed and synthesized.ctrA gene was used for identification of N.meningitidis species.Six serogruops(A,B,C,X,Y,W135)of N.meningitidis were detected with following genes:sacB(A),siaD(B),siaD(C),xcbB(X),synF(Y)and synG(W135)respectively.Sensitivity and specificity of Real-Time PCR were assessed for different primers and probes.121cerebrospinal fluid(CSF)specimens from suspected N.meningitidis invasive meningitis cases were detected by latex agglutination test and Real-Time PCR assay simultaneously.Resuits 79 N.meningitidis isolates of different serogroups could be detected and identified by seven sets of primers and probes in this study.Real-Time PCR seemed more sensitive than standard PCR bv 101-103 times.The respective sensitivities for ctrA,sacB,siaD(B),siaD(C),xcbB,synF and synG were 8,8,80,8,8,80,8 genomeDNA copies in each reaction.Of the 121 CSF specimens,11 were positive for Real-Time PCR and 6 for latex agglutination test.Conclusion Real-Time PCR could rapidly detect and identify N.meningitidis of different serogroups and seemed more sensitive.It could be widely used for diagnose of invasive meningitis caused bv N.meningitidis.

Objective:To analyze and determine heavy metal content in Paridis Rhizoma from different genus and localities,in order to provide a reference for selecting cultivation areas and establishing the quality standard of Paridis Rhizoma of heavy metals content. Method:Microwave digestion method combined with inductively coupled plasma atomic emission spectrometry method (ICP-AES) method were applied to determine the contents of 6 heavy metals,i.e. As,Cu,Hg,Cd,Pb and Cr in 39 samples of Paridis Rhizoma of different genus and localities in Yunnan Province. Cluster analysis,statistical analysis and principal component analysis (PCA) were used to compare the differences of heavy metals contents in different localities and species. Result:The contents of six heavy metals in Paridis Rhizoma met the ISO international standard of Heavy Metal Limit of Traditional Chinese Medicine-traditional Chinese Medicinal Materials. Under the limited value standard of Green Trade Standards of Importing Medicinal Plants and Preparations,the over-standard rate of heavy metal As was 15.4%,the excess rate of Cd was 5.1%,and the excess rate of Pb was 2.6%. The contents of Cu and Hg conformed to relevant requirements. Cluster analysis,statistical analysis and principal component analysis showed that for the same variety,differences in producing places had significant effects on heavy metal content,while differences in species had little effects. Conclusion:The results of this study indicated that the heavy metal content of Paris planted in and around Dali basically conformed to relevant standards. The differences of heavy metal content in Paris were mainly regional differences,which provided a theoretical basis for standardizing the cultivation of medicinal materials and formulating the limit standards of heavy metals for Paridis Rhizoma.