[Exploration on the reformation of epidemiology teaching mode for postgraduates]

Objective: To explore the suitable teaching mode of epidemiology for postgraduates, so as to provide techniques for improving and enhancing the teaching quality. Methods: The course was divided into three stages according to the teaching progress, which was, traditional teaching, traditional teaching and case discussion, online learning and case discussion. The test scores in three stages were compared respectively, and the students' willingness to teaching methods was investigated by questionnaire. Results: The scores of 214 students showed an upward trend in three stages, and the differences were statistically significant (P<0.001). Most students paid more attention to the knowledge systematization and important knowledge. Most students proposed that the teaching time between theoretical knowledge and case discussion should be evenly distributed. More students chose Chinese literature related to their major as teaching cases. Most students believed that case discussion improved the skills of self-study and communication. Conclusion: The epidemiology course for postgraduate should integrate the traditional teaching and case discussion, with online learning as a supplementary, and take effective methods to evaluate, so as to improve the teaching quality of postgraduate.

[A Meta-analysis on association between statins and colorectal cancer]

Objective: To explore the association between statins and colorectal cancer and provide evidence for the prevention of colorectal cancer. Methods: Literatures about statins and colorectal cancer published from January 2000 to January 2020 were retrieved from CNKI, Wanfang data, PubMed and Cochrane Library database. The literatures which met the inclusion criteria were collected, and the Newcastle-Ottawa Scale and Jadad score were used to assess the studies. Meta-analysis was performed with statistical software Revman 5.0 and Stata 12.1. Results: A total of 31 studies, involving more than 1.62 million subjects, were included in the analysis. The case-control study (RR=0.93, 95%CI: 0.88-0.98), the cohort study (RR=0.75, 95%CI: 0.63-0.88) and the randomized controlled trial (RR=0.79, 95%CI: 0.65-0.97) showed moderate protective effect of statins. Using statin <5 years (RR=0.86, 95%CI: 0.76-0.96), average daily dosage ≥34 mg (RR=0.81, 95%CI: 0.66-0.98) and lipid-soluble statins (RR=0.86, 95%CI: 0.74-0.99) also had preventive effect on colorectal cancer; while lovastatin (RR=1.07, 95%CI: 1.00-1.14) increased the risk of colorectal cancer. Conclusion: Statins have protective effect on colorectal cancer.

[Relationship of telomere length, mitochondrial DNA copy number of peripheral blood with hypertension in coal miners]

Objective: To explore the relationship of telomere length, mitochondrial DNA copy number of peripheral blood with hypertension and the interaction between telomere length and mtDNA-CN on hypertension in coal miners. Methods: A case control study was conducted in a coal mine of Shanxi province from July to December of 2013, in which 325 healthy workers were selected as the control group and 378 workers with hypertension as the case group. The information about general demographic characteristics and life behavior habits of the subjects were collected through questionnaire. Levels of telomere length and mtDNA-CN in peripheral blood were detected by real-time PCR. Unconditional logistic regression was used to examine the association between hypertension and telomere length, mtDNA-CN. The interaction test between telomere length and mtDNA-CN on hypertension was performed by adding the interaction term in the corresponding model. Results: The mean telomere length of the workers in the case group was (1.50±0.55) kb, and that of the control group was (2.01±0.62) kb, the difference between two groups was significant (t=11.68, P<0.001). The correlation analysis showed that telomere length was positively correlated with mtDNA-CN (r=0.157, P=0.002) in the case group. Multivariate analysis showed that telomere length (OR=4.408, 95%CI: 3.012-6.452), age (OR=0.417, 95%CI: 0.284-0.613), BMI (OR=1.357, 95%CI: 1.162-1.584), monthly household income level (OR=0.656, 95%CI: 0.553-0.778) and work duration (OR=1.249, 95%CI: 1.100-1.417) were influencing factors of hypertension. The multiply interaction between telomere length and mtDNA-CN was significant on hypertension (OR=1.267, 95%CI: 1.094-1.468). Conclusions: The results suggest shorter telomere length is a risk factor of hypertension. There is a multiply interaction between telomere length and mtDNA-CN on hypertension. However, the association between mtDNA-CN and hypertension was not found.

[Research on potential interaction between mitochondrial DNA copy number and related factors on risk of hypertension in coal miners]

Objective: To investigate the effects of mitochondrial DNA (mtDNA) copy number in peripheral blood and related factors on the risk of hypertension in coal miners. Methods: A case-control study was conducted in 378 coal miners with hypertension and 325 healthy coal miners recruited from Datong Coal Mine Group. A standard questionnaire was used to collect their general information, such as demographic characteristics, habits and occupational history. Fluorescence quantitative PCR was performed to detect the copy number of mtDNA. Logistic regression model was applied for identifying the related risk factors of hypertension and analyzing the interaction between mtDNA copy number and risk factors. Results: The prevalence of hypertension of high mtDNA copy number was lower than mtDNA copy numberin 0-5.67 group, but the difference was not statistically significant (P=0.414). Alcohol drinking (OR=1.80, 95% CI: 1.26-2.56), family history of hypertension (OR=1.74, 95% CI: 1.20- 2.50), work shifts (OR=0.69, 95% CI: 0.48-0.99), education level (P=0.012) and family monthly income level (P=0.001) were related to the prevalence of hypertension. There were potential interactions between mtDNA copy number and alcohol drinking, family monthly income level, family history of hypertension, respectively. Alcohol drinking was a risk factor for hypertension [1.77 (1.25-2.50)]. Potential interactions between mtDNA copy number and alcohol drinking reduced the risk of hypertension (OR=1.20, 95% CI: 1.07-1.35). Family history of hypertension was a risk factor for hypertension [1.81(1.26-2.59)]. Potential interactions between mtDNA copy number and family history of hypertension reduced the risk of hypertension (OR=1.24, 95%CI: 1.09-1.41). Family monthly income level was a protect factor for hypertension [0.55(0.46-0.66)]. Potential interactions between mtDNA copy number and family monthly income level increased the protection role of hypertension (OR=0.90, 95% CI: 0.86-0.94). Conclusion: mtDNA copy number variation was not significantly associated with the prevalence of hypertension in coal miners, but mtDNA copy number showed multiplication interaction on the prevalence of hypertension with alcohol drinking, family monthly income level as well as family history of hypertension and made their influences weaken.

Silencing effect of lentiviral vectors encod-ing shRNA of Herp on endoplasmic reticulum stress and inflammatory responses in RAW 264.7 macrophages

Herp, a mammalian protein with a ubiquitin-like domain, can be strongly upregulated by endoplasmic reticulum (ER) stress during ER-associated protein degradation. However, the other cellular functions of Herp remain unclear. We explored the effect of Herp on ER stress and inflammatory responses in RAW 264.7 macrophages that had been exposed to tunicamycin or thapsigargin. We successfully constructed recombinant lentiviral vectors for Herp short-hairpin RNA (shRNA) expression to better understand the contribution made by Herp to other signaling pathways. Western blotting revealed that the recombinant Herp lentiviral shRNA vector significantly inhibited the expression of the Herp protein in the thapsigargin-treated RAW 264.7 macrophages. The reverse transcription quantitative polymerase chain reaction results showed that knockdown Herp inhibited the expression of ER stress-related genes during exposure to tunicamycin or thapsigargin. In RAW 264.7 macrophages, knockdown Herp markedly attenuated the expression of inflammatory cytokines when exposed to tunicamycin; however, it strongly enhanced the expression of inflammatory cytokines when exposed to thapsigargin. We concluded that Herp lentiviral shRNA vectors had been successfully constructed; knockdown Herp inhibited ER stress and had a different effect on inflammatory responses in RAW 264.7 macrophages depending on whether they were exposed to tunicamycin or thapsigargin.