【Objective】 To investigate the inhibitory effect of BFD-6b on colorectal cancer cell growth and its preliminary mechanism. 【Methods】 The inhibitory effect of BFD-6b on the growth of various tumor cells （SW480， MCF-7， T47D， SMMC-7721， BEL-7402， 97H， SK-HEP-1， H460， H1299， A549， MS751， and HELA） was investigated by MTT assay； the effect of BFD-6b on apoptosis and cell cycle was detected by flow cytometry； the effect of BFD-6b on the expressions of cell cycle-related proteins and apoptosis-related proteins was examined by Western blotting. 【Results】 BFD-6b inhibited the proliferation of different cancer cells such as SW480， MCF-7， H460， H1299， A549， and HELA. Among all of them， SW480 cells were most sensitive to BFD-6b， and the IC50 value was 7.09 μmol/L. Furthermore， BFD-6b could inhibit the growth of another three colorectal cell （SW620， Lovo， and HCT116 cells）； the IC50 values were 7.23， 8.08 and 8.96 μmol/L， respectively. BFD-6b could downregulate the amount of cyclinD1， cyclinE， and cell cycle-dependent kinase CDC2， thereby arresting the cell cycle at G1 phase. Also， BFD-6b downregulated the expressions of anti-apoptotic proteins Mcl-1 and Bcl-2， and upregulated the expressions of pro-apoptotic proteins BAK and BAX， thus inducing apoptosis of SW480 cells. 【Conclusion】 BFD-6b arrests SW480 cells at G1 phase by downregulating the expressions of cyclinD1， cyclinE and CDC2， and induces SW480 cell apoptosis by downregulating the expressions of Mcl-1 and Bcl-2 and upregulating the expressions of BAK and BAX， thereby inhibiting the proliferation of colorectal cancer SW480 cells.

Objective To investigate the positive time length of nucleic acid detection in 22 confirmed cases of coronavirus disease (COVID-19) in Yangzhou and analyze the influencing factors, and to provide evidence for the prevention and control of the disease. Method A total of 22 confirmed cases were followed up for five weeks. Throat swabs were collected for nucleic acid detection. The relevant data were collected and statistical analysis was conducted on the basis of survival analysis. Results The positive rate of throat swabs was 100%, 100% and 66.67% at 1-2d, 3-4d and 5-7d, respectively, after the onset of COVID-19. The average positive time of all confirmed cases was 16.32 days, including 18.50 days for common type and 13.70 days for light type. The difference was statistically significant (χ²=4.36, P=0.037). Multivariate Cox regression analysis showed that case type (or=0.19, 95%CI:0.06-0.61) and onset visit time (or=0.70,95%CI:0.55-0.88) had an impact on the positive time length of nucleic acid detection. Conclusion The positive rate of respiratory samples is high within one week after the onset of the confirmed cases, and the positive time length of light type cases was shorter than that of common types. The positive time length of nucleic acid detection may be shortened after timely treatment with drugs.

ObjectiveTo explore the impact of Gegen Qinliantang（GQT） on the fecal short-chain fatty acids（SCFAs） metabolism in antibiotic-associated diarrhea（AAD） through targeted metabolomics. MethodA total of 240 SD rats were randomly divided into six groups（n=40， half male and half female）， including blank group， model group， bifidobiogen group（0.15 g·kg^-1）， and GQT high-， medium-， and low-dose groups（10.08， 5.04， 2.52 g·kg^-1）， except for the blank group， clindamycin（250 mg·kg^-1） was given to all groups by gavage for modeling every day for 7 d. After successful modeling， each administered group was gavaged with the corresponding dose of the drug， and the blank and model groups were gavaged with an equal volume of normal saline solution， 1 time/d， for 14 d. At 0， 3， 7， 14 d after the drug intervention， eight rats were randomly selected from each group， respectively. Gas chromatography-time-of-flight mass spectrometry（GC-TOF-MS） was used to perform targeted metabolomic analysis of SCFAs in the feces of rats， and partial least squares-discriminant analysis（PLS-DA） was applied to compare the differences in metabolic profiles between groups at different treatment times， and to compare the changes in the contents of SCFAs in rat feces between groups. ResultPLS-DA results showed that the blank group could be clearly distinguishable from the model group， with GQT exhibiting a closer proximity to the blank group after 7 d of treatment. After further analyzing the composition of SCFAs， it was found that the proportion of acetic acid increased and the proportions of butyric acid， valeric acid， hexanoic acid and isovaleric acid decreased in the model group compared with the blank group. After the treatment with GQT， the proportions of butyric acid， isobutyric acid， valeric acid， and isovaleric acid increased， and the proportions of acetic acid， propionic acid and caproic acid decreased. Subsequent differential analysis revealed that GQT could significantly improve the content of butyric acid， and had a certain retrogressive effect on the contents of valeric acid and hexanoic acid. ConclusionThe medium dose group of GQT can improve the contents of SCFAs in AAD feces after 7 days of treatment， which may be related to the improvement of the composition ratio of SCFAs and the contents of butyric acid， valeric acid and caproic acid.