The antibacterial property of silver nanoparticles has resulted in their widespread application in many fields,so the chance of silver nanoparticles exposure for human increased greatly.Thus,there is urgent need to assess the safety of such particle.So far,most toxicological studies of silver nanoparticles mainly focus on the cytotoxicity using different examination endpoint such as morphology,mitochondrial function,cell proliferation,enzyme activity,and so on.In addition,the in vitro studies on the toxicity of silver nanopoarticles are also reported,few of the study on molecule mechanism of toxicity was reported.This review provided a summary of antibacterial mechanism of silver nanoparticles and the current research situation of the safety.The future research direction of toxicological study of silver nanoparticles is also prospected based on the current knowledge.

Objective To understand the trend of lung cancer mortality of permanent residents in Beijing urban area caused by the influence of per capita tobacco consumption and air pollution.Methods Data of lung cancer mortality,air pollution and tobacco consumption from 1982 to 2005 was collected from published year books and Beijing cancer registration division.Trend analysis was applied to test significance of trend of lung cancer mortality of permanent resident in Beijing urban area.Distributed lag model was applied to determine the influence of per capita tobacco consumption and air pollution on lung cancer mortality by Eviews software package.Results Lung cancer mortality of permanent residents in Beijing urban area elevated from 19.74/100 000 in 1982 to 44.73/100 000 in 2005.In the distributed lag model for lung cancer mortality,with per capita tobacco consumption as independent variable,comprehensive index of air pollution,NO2 and PM10 were not statistical significant,while SO2 had statistical significance(P

In recent years,lead poisoning has gradually become an important public health issue.Usually,children are facing a chronic low-level environmental lead exposure.The damage of lead for children is a dose-effect continual process,involving in nerve,blood,digestive,urinary,immune,endocrine and many other systems,and can affect children's growth.The recent researches on children lead poisoning were reviewed and the biological markers of lead poisoning,detection method of lead in vivo,clinical diagnosis,interventions and models in vitro and in vivo in studies of lead poisoning were summarized.This article would offers scientific researchers effective and convenient scientific basis for further study of the lead toxicity.

Objective To explore the environmental risk factors,periconceptional folate intake and methylenetetrahydrofolate reduetase(MTHFR) gene C667T polymorphism of pregnant women on congenital heart diseases(CHD) in offspring.Methods Retrospective case-control study was carried out to investigate periconceptional folate supplementation and environmental factors in 98 parents with CHD offsprings and 101 parents with normal offsprings.The mothers'MTHFR gene C667T mutation was also identified.The possible risk factors were analyzed by simple and multiple factors Logistic regression methods.Results Six factors were related to the occurrence of CHD in the offspring:education of gestation mother,no prenatal examination,under depressed or nervous condition during pregnancy and maternal exposures to harmful substance;periconceptional folate and compound vitamin supplementation were protection factors.There were significant difference between case and control group in folate supplement(P

Objective To explore the pathogenesis of renal damage induced by melamine and the characteristics of kidney damage in rats.Methods Twenty Wister rats were randomly divided into one control group fed with normal pet food and one exposure group fed with animal food mixed with melamine at 25 mg(/kg?d).After 4 weeks,biochemical indexes of blood were determined,histopathological examination was performed,and kidney/body weight was measured among rats.The kidney slices were observed using light microscopy of animal anatomy.Renal tissues from affected rats were analyzed using high-performance liquid chromatography and mass spectrometry.Kidney X-ray diffraction were performed to determine the existence of crystals Results After 4 weeks of melamine exposure,the rats showed polyuria,less activity,weight loss,increasing levels of serum creatinine,urea nitrogen,triglyceride.The appearance of kidney significantly changed.The diffuse distribution of the point and the flake crystal shadow were observed in kidney slices.Histopathological examination showed the existence of a large number of crystals in renal tubular,renal tubular epithelial damage.The analysis of high-performance liquid chromatography and mass spectrometry revealed that crystals were composed of melamine and cyanuric acid.Kidney X-ray diffraction revealed that crystals could be found in kidneys of rats.Conclusion Melamine can enter the body through the digestive tract and generate partially cyanuric acid through hydrolysis.Then cyanuric acid and melamine formed cocrystals in renal tubules leading to progressive tubular blockage,renal tubular epithelial damage,tubular reabsorption dysfunction,eventually renal failure.

Objective To construct expressing recombinant of recF and recO from Deinococcus radiodurans R1and express the target protein in E.coli BL21(DE)3.Methods recF and recO gene were amplified by PCR from genomic DNA of Deinococcus radiodurans R1 and inserted into expression plasmid vector pET30b(+) to construct pET30b(+)-recF and pET30b(+)-recO.The recombinant plasmids were transformed into E.coli BL21(DE)3 and the recombinant proteins were expressed by the isopropyl-?-D-thiogalactopyranoside(IPTG) and were analyzed with SDS-PAGE.The changes in the survival rate of bacteria in each group before-and after UV-irradiation were calculated.Results The recombinant plasmid pET30b(+)-recO and pET30b(+)-recF was obtained and the recombinant protein could be highly expressed in E.coli BL21(DE)3.Conclusion This study has provided a foundation for further studies and applications of the recombinant RecF and RecO,and initial detection shows that recO and recF gene can increase the resistant ability of E.coli.

Objective To observe urinary iodine levels in the rat model for excessive iodine intake and monophagia.Methods Wistar rats were randomly divided into 8 groups:normal diet control group(NC),10-fold iodine + normal diet group(10 HI-N),50-fold iodine + normal diet group(50 HI-N),100-fold iodine + normal diet group(100 HI-N),monophagia control group(MC),10-fold iodine + monophagia group(10 HI-M),50-fold iodine + monophagia group(50 HI-M),100-fold iodine + monophagia group(100 HI-M).The excessive iodine intake groups exposed to 1 400,7 600,15 350 ?g/L I-through drinking water presented higher levels of daily iodine intake,which were 10,50,100 times of those in control groups.During the exposure period,the body weights of the rats were measured weekly,the levels of urinary iodine were determined at the second,the fourth and the sixth month.Results The body weights of the excessive iodine intake groups with monophagia were lower than that of the NC group.In normal diet groups and monophagia diet groups,the levels of urinary iodine increased with the increase of iodine intake.The levels of urine iodine in 50 HI-M group and 100 HI-M group were significantly higher than those of the related groups with higher iodine intake.Conclusion The experimental animal model of excessive iodine intake and monophagia are successfully established in the present research,with physical retardation and higher urinary iodine.

Objective To establish a method for the determination of Ca2 + cations in the nutritive food by ion chromatography.Methods After being digested by the mixture of nitric acid and perchloric acid,the Ca2+ cations in the nutritive food were determined by ion chromatography(IC).Results The optimum chromatographic conditions were studied thoroughly,the linear range was 0.10-500 mg/L,r=0.9998.The lowest detection limit of Ca2+ cations in nutritive food was 0.02 mg/L,RSDs were 0.50%-4.00%,the rates of recovery tested by the standard addition method were in the range of 95.0%-103.0%.Conclusion This method is simple,fast,sensitive and accurate.

Objective To explore the association between the minimum temperature in different seasons and the hospital emergency room visits for cardiocerebrovascular diseases(International Classification of Diseases,tenth vision ICD-10:I00-I99) in Beijing,China.Methods The data of the daily hospital emergency room visits for cardiocerebrovascular diseases(ICD-10:I00-I99)from one of Peking university hospitals,the data of relevant ambient air pollution from the Beijing Municipal Environmental Monitoring Center and the data of meteorological index from China meteorological data sharing service system between 2004— 2006 were collected The time-stratified case-crossover design was used to analyze the data.Results After adjusting SO2,NO2,and PM10,the results showed that each 1 ℃ increase in the daily minimum temperature in summer was associated with the intraday hospital emergency room visits(OR=1.039,P

Polybrominated diphenyl ethers(PBDEs) are widely present in the world and their concentration in the environment has been increasing rapidly.PBDEs pollution has caused an extensive concern in recent years.The environmental effects of PBDEs are decided by their transfer and transformation,which is the basis of environmental and health risk evaluation.At present,a considerable number of detection of PBDEs has been undertaken in sediment and wildlife.However,little research has been done on the ecotoxicology of PBDEs.The purpose of this paper was to introduce the research status of PBDEs,to summarize emphatically their distribution model,bioaccumulation regularity and ecotoxicology effects in the environment,and to discuss the influences of PBDEs on human health.Finally the problems needed to be solved in this field are proposed.