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Objective: To investigate a cluster epidemic of COVID-19 after a mass gathering activity in Ningbo of Zhejiang province and analyze the transmission chain and status of infection cases of different generations. Methods: The tracking of all the close contacts of the first COVID-19 case and epidemiological investigation were conducted on January 29, 2020 after a cluster epidemic of COVID-19 related with a Buddhism rally on January 19 (the 1.19 rally) in Ningbo occurred. The swabs of nose/throat of the cases and close contacts were collected and tested for nucleic acids by real-time fluorescence quantitative RT-PCR. Results: From January 26 to February 20, 2020, a total of 67 COVID-19 cases and 15 asymptomatic infection cases related with the 1.19 rally were reported in Ningbo. The initial case was the infection source who infected 29 second generation cases and 4 asymptomatic infection cases, in whom 23 second generation cases and 3 asymptomatic infection cases once took bus with the initial case, the attack rate was 33.82% (23/68) and the infection rate was 38.24% (26/68). The risks of suffering from COVID-19 and being infected were 28.91 times and 26.01 times higher in rally participants taking bus with initial case compared with those taking no bus with initial case. In this epidemic, 37 third+generation cases and 11 related asymptomatic infection cases occurred, the attack rate was 2.88% (37/1 283) and the infection rate was 4.76% (48/1 008). The main transmission routes included vehicle sharing and family transmission. Conclusion: It was a cluster epidemic of COVID-19 caused by a super spreader in a massive rally. The epidemic has been under effective control.

Objective: To describe the basic characteristics of clusters of coronavirus diseases 2019 (COVID-19) cases in Ningbo, Zhejiang province, and evaluate the generation time (Tg) and basic reproduction number ( R (0)) of COVID-19. Methods: The basic information and onset times of the clusters of COVID-19 cases in Ningbo were investigated, the inter-generational interval of the cases were fitted by using gamma distribution, and the R (0) was calculated based on the SEIR model. Results: In the 15 clusters of COVID-19 cases, a total of 52 confirmed cases, 5 cases of nucleic acid-positive asymptomatic cases. The cases occurred from January 23 to February 4, the cases were mainly women. The incubation period was (6.11±3.38) days, and the median was 5 days. The Tg was (6.93±3.70) days. There were no significant differences in Tg between age group<60 years and age group 60 years and above, and between men and women ( P =0.551). According to the Tg calculated in this paper, the R (0) of COVID-19 in Ningbo was 3.06 (95 %CI : 2.64- 3.51); according to the reported case transmission interval of 7.5 days in the literature, the R (0) was 3.32 (95 %CI : 2.51-9.38). Conclusion: There is no age and gender specific differences in the Tg of clusters of COVID-19 cases in Ningbo, and COVID-19 has high infectivity and spreading power in early phase.

Objective: To explore the short-term effects of ambient PM(2.5) on the outpatient visits of chronic obstructive pulmonary disease (COPD) in Ningbo city. Methods: Through the regional health information platform, number of daily COPD outpatients from the four general hospitals in Ningbo was gathered. Related data on meteorological and air pollution from 2014 to 2016 was also collected. Generalized additive model (GAM) of Possion regression was used to estimate the impact of PM(2.5) pollution on COPD outpatients and the lagging effects. Results: In cold (November- April) or warm seasons (May-October), an 10 μg/m(3) increase of PM(2.5) would result in the excessive number of COPD outpatients as 1.87% (95 %CI : 0.98%-2.76%), 2.09% (95 %CI : 1.11%-3.08%) and 2.56% (95 %CI : 0.56%-4.59%), respectively. In terms of the short-term effects of PM(2.5) the strongest was seen in the days of warm season but without delay ( P <0.05). The strongest effect appeared at day 4 in cold season and the effect was particularly significant seen in the over 65 year-old group or in the female population. After the introduction of PM(10), SO(2) and NO(2), the concentration of PM(2.5), did not show significant effect on the number of hospital visits due to COPD on the same day ( P >0.05). The effect of COPD on the fourth day showed a slight change after the lagging, and the effect was statistically significant ( P <0.05). Conclusion: The increase of PM(2.5) concentration in Ningbo was related to the increase of COPD outpatient numbers. Effective prevention measures should be taken to protect the vulnerable population and to reduce the risk of COPD.

Objective: To study the influence of daily air temperature on daily chronic obstructive pulmonary disease (COPD) mortality in residents in Ningbo. Methods: A time-series analysis using distributional lag non-linear model (DLNM) was conducted to estimate the attributable numbers and fraction of average air temperature on the daily COPD mortality in Ningbo from 2011 to 2016, by controlling the long-term time trend, day of week, air pollutants and other weather variables. Results: A reverse J-shape relationship was found between the average air temperature and COPD mortality, and the minimum-mortality temperature (MMT) was 25.5 ℃. The relative risks of extreme low and extreme high air temperature over lag 0-14 d were 2.767 (95 %CI : 1.950-3.928) and 1.197 (95 %CI : 1.021-1.404). In total, 31.62% (95 %CI : 23.05%-38.89%) of COPD mortality (4 963 cases, 95 %CI : 3 469-6 027) was attributable to non-MMT exposure, More attributable deaths were due to low air temperature, with a fraction of 30.41% corresponding to 4 772 deaths, compared with 1.22% and 192 deaths due to high air temperature. Low air temperature and high temperature were more likely to influence the mortality in females and those aged ≥65 years, but the influence was not significant in people aged <65 years. Conclusion: Both high and low air temperature were associated with an increased risk of COPD mortality in residents in Ningbo, especially during cold season, related measures on disease prevention should be taken to protect vulnerable population to reduce the risk of COPD mortality.

Objective: To explore the main effects of weather factors on heat stroke., Methods: Data from case report on heat stroke was collected in Ningbo city during 2011 to 2014. Temperature threshold, lag effects and interaction of weather factors on heat stroke had been analyzed, using the piecewise regression model, distributed lag non-linear model, response surface model and other methods., Results: RESULTS showed that temperature and humidity were more correlated with heat stroke than other weather-related factors. Through different models, daily average temperature always presented a better role in predicting the heat stroke, rather than maximum or minimum temperature. Positive association between daily average temperature and heat stroke was obvious, especially at lag 0-1 days, with its threshold as 29.1 (95% CI: 28.7-29.5) ℃ . The cumulative RR of heat stroke at 90(th) percentile of daily average temperature versus 10(th) percentile was 14.05 (95% CI: 7.23-27.31) in lag 0-1 days. The effects of daily relative humidity on heat stroke appeared nonlinear, with low humidity showing a negative effect on heat stroke and could lag for 1-4 days. However, the effect of high humidity was not significant, with the cumulative RR of low humidity and high humidity as 2.35 (95%CI: 1.27-4.33) and 0.86 (95%CI: 0.40-1.85) in lag of 0-4 days, respectively. We also noticed that there was an interactive effect of both temperature and humidity on heat stroke. Under high temperature and low humidity, the risk of heat stroke showed the highest., Conclusions: Temperature and humidity showed obvious relationship with heat stroke in Ningbo city, with the threshold temperature as 29.1 ℃. Under high temperature and low humidity, the risk of heat stroke became the highest.

Objective: To explore the short-term effect of particulate matters with an aerodynamic diameter of less than or equal to 10 μg (PM10) and aerodynamic diameter of less than or equal to 2.5 μg (PM2.5) on cardio-cerebrovascular mortality in Ningbo city., Methods: Daily cardio-cerebrovascular mortality data from 2011 to 2014 in Ningbo city were collected and the time series study using a semi-parametric generalized additive model were used to evaluate the relationship between the mortality of cardio-cerebrovascular disease and particulate matters after adjustment for the long-term trend of death,weather conditions, "days of the week" and other confounding factors., Results: In single-pollutant model, the short-term effects of particulate matter on cardio-cerebrovascular mortality was strongest in lagged 2 days in Ningbo city, and an increase of 10 μg/m(3) in moving average concentrations (lagged 2-3 days and lagged 2-4 days) of PM2.5 and PM10 could increase the cardio-cerebrovascular mortality by 0.55% (0.23%-0.87%) and 0.53% (0.28%-0.78%), respectively. In multi-pollutant models, PM10 did remain robust after being adjusted for PM2.5 with 0.58% (0.09%-1.07%) increase in cardio-cerebrovascular mortality. The effect of PM2.5 had no statistical significantce after being adjusted for other co-pollutants., Conclusion: These findings suggested that the concentrations of ambient particulate matters were associated with an increased risk of daily cardio-cerebrovascular mortality in Ningbo city.

Pig oocytes are surrounded by an acellular translucent envelope-zona pellucida(pZP), which is comprised of three biochemically and immunologically distinct glycoproteins(pZP1, pZP3 alpha and pZP3 beta). Due to the cross-reactivity of anti-pZP3 beta antibodies with human ZP in vitro, pZP3 beta has been considered as potential one of immunogens for developing human contraceptive vaccine. In order to express pZP3 beta directly in E. coli; we amplified the core fragment of pZP3 beta cDNA by PCR that was deleted 5'- and 3'-terminal sequences of coding for signal peptide and transmembrane-like domain. The DNA sequenced EcoRI and SalI restriced core fragment was cloned in a frame downstream of PRPL promoter in the pBV221 vector. SDS-PAGE analysis showed that pZP3 beta protein was expressed especially in E. coli after thermal induction, which the expression band displayed the molecular weight of about 38 kD matching with its deduced molecular weight(36.5 kD). In addition, the specially expressed protein band on SDS-PAGE gel showed specific immunological reaction with anti-pig ZP IgGs of rabbit in Western blot.