Objective To establish a method for the simple and rapid extraction and detection of nitrosodipropulamine(NDPA).Methods NDPA at levels of?g /L grade in chemical industrial wastewater was enriched efficiently using the purge and trap(P&T)method with a Trap3tube under the standard program,including the flow rate of purge gas(40ml/min),the time of purge(11min),the temperature of desorb(225℃),the time of desorb(4min),the temperature of bake(230℃)and the time of bake(10min).The NDPA concentrations were determined by gas chromatography-mass spectroscopy(GC-MS )and chemical ionization(CI )and select ion mode(uSIS)coupled with the purge and trap(P&T)(P&T/GC-MS/CI /uSIS)method Results The detection limit,recovery rates and relative standard deviation(RSD)of the method were3?g /L,62.60%-96.31%and7.5%respectively.The linearity of method was good in the5-30?g /L range with the correlation coefficient 0.978.Conclusion The P&T/GC-MS/CI /uSIS method could be used to detect semi-volatile NDPA in chemical industrial wastewater.

Objective To evaluate the relationship between 5,10-Methylenetetrahydrofolate reductase(MTHFR) gene polymorphisms and colorectal cancer(CRC).Methods Studies were selected based on the criteria for inclusion.The Meta-analysis software,REVMAN 4.2,was applied for checking the heterogeneity across the studies and calculating the pooled OR.The results were evaluated by the analyses of publication bias and sensitivity.Results A total of 9 787 cases and 12 986 controls from 18 studies for C677T and a total of 4 422 cases and 5 819 controls from 9 studies for A1 298C were included.No heterogeneity among the studies was found.For codon 677,the frequencies of CC,CT and TT genotypes were 46.48%,43.81% and 9.71% in cases,and 45.03%,43.08% and 11.89% in controls,respectively.The pooled OR of TT vs.CT+CC was 0.80(95%CI 0.74～0.87).For codon 1 298,the frequencies of AA,AC and CC genotypes were 53.60%,39.39% and 7.01% in cases,and 53.31%,38.67% and 8.03% in controls,respectively.The pooled OR of CC vs.AC+AA was 0.84(95%CI 0.72～0.97).Conclusions MTHFR 677TT is at lower risk of developing CRC and 1 298CC genotypes might be associated with the decreased risk of developing CRC.

Objective To explore the expressions and distributions of glial cell line -derived neurotrophic factor (GDNF)and itstyrosine kinase receptor RET in the terminal rectums of fetal rats with congenital anorectal malfor-mations (ARM)at different gestationalage,and to explore their effects on the enteric nervous system in the terminal rectum of ARMfetal rats.Methods Thirty -five SD pregnancy rats were divided into a saline group (n =1 0)and an ethylenethiourea experiment group (n =25)by simple randomized study.The fetal rats were removed from the pregnant rats at the gestational 1 6 d,1 8 d and 20 d.The fetal rats were divided into the saline control group,the ethylenethiourea control group (fetal rats without ARM)and the ethylenethiourea malformation group (ARM fetal rats)by the naked eye and dissecting microscope.HE staining was used to observe the morphology and the intestinal ganglion cells in the terminal rectum were counted.The immunohistochemical staining and Western blot methods were used to observe the distributions of GDNF and RET in the rectum at the gestational 1 6 d,1 8 d and 20 d.The quantitative real -time poly-merase chain reaction (qRT -PCR)was used to detect the expression of GDNF mRNA in the fetal rats in the terminal rectum at the gestational 1 6 d,1 8 d and 20 d.Results HE staining:the development of anorectal terminal in 3 groups of fetal rats was unclear at the gestational 1 6 d.A small amount of scattered nerve plexuses were observed in the muscu-lar layer.The nuclei were small and sparse.The axons and cytoplasms were less.The serosal layer,muscular layer,sub-mucosa,mucosal layer and glands in the terminal rectum were gradually clear in the saline control group and the ethyle-nethiourea control group at the gestational 1 8 d and 20 d.The intermuscular submucosal nerve plexuses increased gra-dually (1 1 .400 ±3.1 34 and 1 1 .200 ±3.425 at the gestational 1 8 d;66.1 00 ±4.954 and 67.600 ±5.481 at the gesta-tional 20 d).While,the layer was unclear in the ethylenethiourea malformation group and the nerve plexus was less (7.800 ±1 .989 at the gestational 1 8 d,and 25.200 ±3.048 at the gestational 20 d),and the difference was statistical-ly significant compared with 2 control groups (F =7.591 ,271 .833,all P <0.05).Immunohistochemistry satning:the expressions of GDNF and RET in all layers of the intestinal wall in the 3 groups of fetal rats were unclear at the gesta-tional 1 6 d and only a few positive cells were observed.The GDNF and RET were expressed in the mucosal layer and submucosa of the terminal rectum as well as intermuscular nerve plexus in the saline control group and the ethylene-thioured control group at the gestational 1 8 d and 20 d.With the continuous development of the embryo,their expression intensities were gradually increased.The expressions of GDNF and RET positive cells were decreased gradually in the ethylenethiourea malformation group.The difference was significant statistically compared with 2 control groups (all P <0.05).qRT -PCR:the expressions of GDNF mRNA showed no statistical difference among 3 groups at the gestational 1 6 d (P >0.05);the expressions of GDNF and RET protein were 1 03.624 ±27.533 and 1 05.1 84 ±1 9.634 at the ges-tational 1 8 d;1 51 .496 ±33.622 and 1 50.738 ±21 .423 at the gestational 20 d in 2 control groups.Compared with the ethylenethiourea malformation group (79.1 69 ±1 1 .697 at the gestational 1 8 d;94.873 ±1 1 .309 at the gestational 20 d),and the difference were statistically significant (all P <0.05).Conclusions The expressions of GDNF and its tyrosine kinase receptor RET had a certain temporal correlation in the terminal rectum of normal fetal rats at different gestational ages and ARM.Moreover,the abnormal expressions of GDNF and its tyrosine kinase receptor RET in the dis-tal rectum of ARMfetal rats can affect the development of enteric nervous system.

Objective: To investigate the factors influencing the development of gastric cancer in Chinese populations, so as provide insights into creating a model for predicting gastric cancer incidence among Chinese populations. Methods: The case-control and cohort studies pertaining to factors affecting the development of gastric cancer were retrieved in electronic Chinese and English databases, including CNKI, Wanfang Data, VIP, PubMed, Web of Science and Embase from their inception until September 30, 2021. A meta-analysis was performed using R package version 4.1.0. Sensitivity analysis was performed using the “leave-one-out” evaluation procedure, and the publication bias was evaluated using the Egger regression test and the trim-and-fill procedure. Results: A total of 5 301 publications were screened and 116 eligible studies were included in the final analysis, including 103 case-control studies and 13 cohort studies, which covered approximately 3.23 million study subjects. A total of 45 factors affecting the development of gastric cancer were collected, and there were less than 4 publications reporting 7 factors, which were only qualitatively described. There were 38 factors included in the final meta-analysis. A total of 21 factors were identified as risk factors of gastric cancer, including a history of gastrointestinal diseases (pooled OR=4.85, 95%CI: 3.74-6.29), H. pylori infection (pooled OR=3.18, 95%CI: 2.35-4.32), binge eating and drinking (pooled OR=2.88, 95%CI: 2.09-3.97) and a family history of tumors (pooled OR=2.78, 95%CI: 2.17-3.56), and 10 factors as protective factors, including vegetable intake (pooled OR=0.48, 95%CI: 0.38-0.61), tea consumption (pooled OR=0.55, 95%CI: 0.47-0.64), administration of aspirin (pooled OR=0.53, 95%CI: 0.31-0.92) and administration of statins (pooled OR=0.59, 95%CI: 0.44-0.80). Sensitivity analyses of eating moldy food frequently, white meat intake, favoring spicy food and administration of sulfonylureas were not robust. Following correction with the trim-and-fill procedure, there was still a publication bias pertaining to high income, diabetes, administration of stains, alcohol consumption, tea consumption and white meat intake. Conclusions The development of gastric cancer is associated with a medical history of gastrointestinal disease, H. pylori infection, family history of tumors and poor dietary habits. Risk and protective factors of gastric cancer are recommended to be included in models used to predict gastric cancer incidence among Chinese populations.

Objective This study aimed to describe the sex disparities on cancer incidence and mortality in Jiashan population.Methods All data concerning incident and death cases of cancers were gathered from the database of Cancer Registry in Jiashan county.Data from the 2010 China census was used as the standard population.Sex-specific age-standardized incidence rates (ASIRs),mortality rates (ASMRs) per 100 000 persons for all cancers and types of each cancer were calculated for the years of 1990 to 1999,2000 to 2009,2010 to 2014,and 1990 to 2014.In addition,the corresponding male-to-female incidence rate ratios (IRRs) and mortality rate ratios (MRRs) were also calculated.Results The ASIR of all cancers was 226.13/105 for the whole period of 1990 to 2014,with 266.04/105 for males and 187.22/105 for females,respectivcly.The corresponding IRR was 1.42 (95％CI:1.39-1.46),with significant difference noticed in the incidence rates between males and females (P＜0.05).The ASMR of all cancers was 155.39/105,with 206.55/105 for males and 104.98/105 for females,respectively.The corresponding MRR was 1.97 (95％ CI:1.91-2.03),with significant difference between males and females (P＜0.05).Among all the cancer types,only gallbladder cancer and thyroid cancer showed female predominance in both incidence and mortality,with male predominance in all the remaining cancers.Conclusion Finding from our study suggested that a male predominance in both incidence and mortality for a majority of cancers in Jiashan population.

Epidemiology is one of main courses for undergraduate students majoring in preventive medicine.There are some limitations in the traditional epidemiology teaching,which is usually characterized in indoctrinated education:"lectured by the teachers and listened by the students." In Zhejiang University,staff of the epidemiology division tried to explore a new teaching mode as ‘student-centered,teacher-leading,question-based,and combining with literature discussion and course practice.'After practicing for two years,students were inspired in learning initiatives,with teaching effectiveness obviously improved.

Objective:To compare the application effect of domestic and imported intravenous radiofrequency closure system in the treatment of primary varicose veins of lower extremities.Methods:This single-center prospective, non-inferiority randomized controlled trial was performed in the Department of Vascular Surgery, the Fourth Affiliated Hospital, Zhejiang University School of Medicine from January 2021 to January 2022. Patients with primary varicose veins of lower extremities who met the ataxation criteria were randomly assigned to the experimental group(domestic novel venous radiofrequency closure system) or the control group(imported venous radiofrequency closure system) in a ratio of 1∶1. The two groups of subjects were compared in terms of target vein closure rate, technical success rate, system operation performance, incidence of adverse events and incidence of serious adverse events(SAE) within 6 months after surgery. Quantitative data were compared by Mann-Whitney U test, and categorical data were compared by χ2 test and non-inferiority test. Results:A total of 80 subjects were included in the trial (41 in the experimental group and 39 in the control group), including 27 males and 53 females, aged ( M(IQR)) 55(23) years (range:40 to 78 years). There were 48 cases of left lower limb and 32 cases of right lower limb. The technical success rate and system control performance between the groups were 100%.The incidence of adverse events (58.5% (24/41) vs. 61.5% (24/39), χ2=0.075, P=0.784), and the incidence of SAE (7.3% (3/41) vs. 5.1% (2/39), χ2=0.163, P=0.686) within 6 months after surgery in experimental group and control group had no statistical significance. There was one device-related adverse event in each of the two groups. In the experimental group, one patient developed endovenous heat-induced thrombosis after surgery and recovered after taking rivaroxaban tablets. One patient in the control group had pain in the upper right thigh for more than 1 day after operation, which was cured after using analgesic cream. No device-related SAE occurred. The venous closure rate of the experimental group was 100% (38/38) at 6 months after surgery, and that of the control group was 97.4% (37/38). The difference between the two groups was 2.63% (95% CI:-3.19 to 8.45, Z=4.865, P<0.01), and the 95% CI lower limit of the difference in target venous closure rate between two groups was greater than the non-inferiority threshold of -10.00%. Conclusion:The early application effect of the new domestic intravenous radiofrequency closure system in patients with primary varicose veins of lower extremities is in line with expectations, it is not inferior to the imported system.

Objective:To compare the application effect of domestic and imported intravenous radiofrequency closure system in the treatment of primary varicose veins of lower extremities.Methods:This single-center prospective, non-inferiority randomized controlled trial was performed in the Department of Vascular Surgery, the Fourth Affiliated Hospital, Zhejiang University School of Medicine from January 2021 to January 2022. Patients with primary varicose veins of lower extremities who met the ataxation criteria were randomly assigned to the experimental group(domestic novel venous radiofrequency closure system) or the control group(imported venous radiofrequency closure system) in a ratio of 1∶1. The two groups of subjects were compared in terms of target vein closure rate, technical success rate, system operation performance, incidence of adverse events and incidence of serious adverse events(SAE) within 6 months after surgery. Quantitative data were compared by Mann-Whitney U test, and categorical data were compared by χ2 test and non-inferiority test. Results:A total of 80 subjects were included in the trial (41 in the experimental group and 39 in the control group), including 27 males and 53 females, aged ( M(IQR)) 55(23) years (range:40 to 78 years). There were 48 cases of left lower limb and 32 cases of right lower limb. The technical success rate and system control performance between the groups were 100%.The incidence of adverse events (58.5% (24/41) vs. 61.5% (24/39), χ2=0.075, P=0.784), and the incidence of SAE (7.3% (3/41) vs. 5.1% (2/39), χ2=0.163, P=0.686) within 6 months after surgery in experimental group and control group had no statistical significance. There was one device-related adverse event in each of the two groups. In the experimental group, one patient developed endovenous heat-induced thrombosis after surgery and recovered after taking rivaroxaban tablets. One patient in the control group had pain in the upper right thigh for more than 1 day after operation, which was cured after using analgesic cream. No device-related SAE occurred. The venous closure rate of the experimental group was 100% (38/38) at 6 months after surgery, and that of the control group was 97.4% (37/38). The difference between the two groups was 2.63% (95% CI:-3.19 to 8.45, Z=4.865, P<0.01), and the 95% CI lower limit of the difference in target venous closure rate between two groups was greater than the non-inferiority threshold of -10.00%. Conclusion:The early application effect of the new domestic intravenous radiofrequency closure system in patients with primary varicose veins of lower extremities is in line with expectations, it is not inferior to the imported system.

Objective:To explore the association between lifestyle-related factors and colorectal adenoma.Methods:Based on the Screening Project of Early Diagnosis and Treatment of Colorectal Cancer in Jiashan county Zhejiang province, from August 2012 to March 2018, information gathered through records on questionnaire and colonoscopic diagnosis were collected from participants with positive results during the primary screening stage. According to the findings of colonoscopy, 11 232 controls without any colorectal diseases and 3 895 cases with colorectal adenoma were included in the study. Multivariate logistic regression models were used to analyze the association between lifestyle-related factors and colorectal adenoma.Results:After adjusting for possible confounding factors, results from multivariate logistic regression analysis showed that smoking, alcohol drinking and obesity were positively related to the risk of colorectal adenoma, with ORs (95 %CIs) as 1.38 (1.24-1.54), 1.37 (1.24-1.51) and 1.38 (1.20-1.59) respectively. However, regular aspirin intake was negatively related with the risk of colorectal adenoma ( OR=0.65, 95 %CI: 0.53-0.80). After stratified by sex and age, data showed that the associations between smoking, alcohol drinking and colorectal adenoma were statistically significant in males, and the association between regular aspirin intake and colorectal adenoma was also statistically significant in older participants (aged 60 years and older). Conclusion:Smoking, alcohol drinking, regular aspirin intake and obesity were associated with colorectal adenoma.