[TAN Bayesian network modeling of online learning decision making of dental undergraduates during the COVID-19 pandemic].

PURPOSE: To perceive the dental undergraduate's policy of coping with online learning and their decision-making laws during the COVID-19 pandemic. METHODS: For dental undergraduate students from the 2016 grade to 2018 grade of Lishui University, two prospective questionnaire surveys were conducted before the online course starting and four weeks later. SPSS Modeler18.0 software was used to screen, review, and analyze the data. TAN (tree augmented naive) Bayesian network models were utilized to analyze and predict variables. Indicators like the overall prediction accuracy, receiver operating characteristic curve (ROC curve), and area under the ROC curve(AUC value) were applied to evaluate the model's predicting performances. RESULTS: The case score of each survey was 422 and 382, and the Cronbach's α coefficients of internal consistency were 0.91 and 0.82. Among the decision-making variables in the aspect of "whether to preview online learning materials", the top-two variables were "looking forward to the semester beginning" and "the validity of the network materials". In speaking of "whether the online courses meet the offline course standards", the top-three variables were "the rhythm of lecturing on live or in recorded videos", "how many online tasks', and" the data frame and organization". The overall prediction accuracy of each constructed TAN Bayesian network model was 89.42% and 87.82%, and their AUC values were 0.75 and 0.93, respectively. CONCLUSIONS: To truly make online courses comparable to the off-line curriculum, teachers should fully understand how the students cope with their online learning at first. Then, only by perceiving and recognizing the students' expectations for education, by efficiently preparing and organizing online materials with all-round, clearly-structured, vivid, comprehensible contents and moderate difficult tasks, by well interacting with students through different websites and social media, can we truly achieve " ongoing learning with suspended class".

Microbial conversion of major ginsenosides in ginseng total saponins by Platycodon grandiflorum endophytes.

BACKGROUND: In this study, we screened and identified an endophyte JG09 having strong biocatalytic activity for ginsenosides from Platycodon grandiflorum, converted ginseng total saponins and ginsenoside monomers, determined the source of minor ginsenosides and the transformation pathways, and calculated the maximum production of minor ginsenosides for the conversion of ginsenoside Rb1 to assess the transformation activity of endophyte JG09. METHODS: The transformation of ginseng total saponins and ginsenoside monomers Rb1, Rb2, Rc, Rd, Rg1 into minor ginsenosides F2, C-K and Rh1 using endophyte JG09 isolated by an organizational separation method and Esculin-R2A agar assay, as well as the identification of transformed products via TLC and HPLC, were evaluated. Endophyte JG09 was identified through DNA sequencing and phylogenetic analysis. RESULTS: A total of 32 ß-glucosidase-producing endophytes were screened out among the isolated 69 endophytes from P. grandiflorum. An endophyte bacteria JG09 identified as Luteibacter sp. effectively converted protopanaxadiol-type ginsenosides Rb1, Rb2, Rc, Rd into minor ginsenosides F2 and C-K, and converted protopanaxatriol-type ginsenoside Rg1 into minor ginsenoside Rh1. The transformation pathways of major ginsenosides by endophyte JG09 were as follows: Rb1→Rd→F2→C-K; Rb2→C-O→C-Y→C-K; Rc→C-Mc1→C-Mc→C-K; Rg1→Rh1. The maximum production rate of ginsenosides F2 and C-K reached 94.53% and 66.34%, respectively. CONCLUSION: This is the first report about conversion of major ginsenosides into minor ginsenosides by fermentation with P. grandiflorum endophytes. The results of the study indicate endophyte JG09 would be a potential microbial source for obtaining minor ginsenosides.

[Cloning and expression of transferrin protein from Culex pipiens pallens and a study of its antimicrobial activity].

OBJECTIVE: To clone and express transferrin (Tsf) from Culex pipiens pallens in Pichia pastoris, and detect its antibacterial activity. METHODS: The coding region of transferrin from Culex pipiens pallens was amplified by RT-PCR. The product of RT-PCR was inserted into the downstream of gene encoding a-factor signal sequence in a Pichia pastoris secreting expression vector pGAPZalpha-A. The recombinant pGAPZalpha-A-Tsf vector was transformed into P. pastoris GS115 by electroporation. Recombinant strains pGAPZa-A-Tsf/GS115 were screened by Zeocin resistance and PCR. Recombinant protein was detected by SDS-PAGE and Western blotting. The recombinant transferrin protein was purified by using Ni-NTA resin. The antibacterial activity of the purified transferrin against Escherichia coli was detected. RESULTS: The transferrin gene with 2,100 bp was obtained by RT-PCR. The product of recombinant plasmid pGAPZalpha-A-Tsf was approximately 2 127 bp by double digestion with restriction enzymes, consistent with the anticipated fragment length. Sequencing results showed that the inserted sequence was correct. PCR result showed that the recombinant plasmid pGAPZalpha-A-Tsf/GS115 was constructed. The results of SDS-PAGE and Western blotting showed that the relative molecular weight (Mr) of the protein was about 80,200. The recombinant transferrin protein showed antibacterial activity against Escherichia coli, and the minimum concentration was 0.25 mg/ml. CONCLUSION: The recombinant transferrin protein from Culex pipiens pallens has been expressed in P. pastoris, and shows antibacterial activity against E. coli.

Effects of microRNA-21 on the interleukin 12/signal transducer and activator of transcription 4 signaling pathway in asthmatic mice.

OBJECTIVE: To study the effect of microRNA-21 (miRNA-21) on the regulation of the interleukin 12 (IL-12)/signal transducer and activator of transcription 4 (STAT4) pathway in the lung tissue of asthmatic mice. MATERIAL AND METHODS: Forty five male C57BL/6 mice were randomly divided into three groups of 15 mice each: normal control, asthmatic model, and dexamethasone. Our mouse model of allergic asathma was established using OVA sensitization and challenge. Hematoxylin and eosin staining was performed to observe the pathological changes in lung tissue morphology. Both the total cell number and the amount of eosinophils (EOS) in the bronchoalveolar lavage fluid (BALF) were manually counted. The expression of miRNA-21 was detected by real time quantitative PCR. The expression levels of IL-12 and STAT4 in lung tissue were assayed via western blot, and immunohistochemistry was used to observe the distribution of their expression. RESULTS: The expression levels of miRNA-21 as well as the total number of BALF cells and EOS were significantly higher in the asthmatic model group than in the control or dexamethasone groups, with significantly higher amounts found in the dexamethasone group than in the control group. The expression levels of IL-12 and STAT4 proteins were lower in the asthmatic model group than in the control and dexamethasone groups, with a significantly lower expression of IL-12 and STAT4 in the dexamethasone group than in the control group. CONCLUSIONS: The expression level of miRNA-21 was significantly increased and the expression level of IL-12 and STAT4 proteins was significantly decreased in allergic asthmatic mice compared with normal control mice. These findings suggest a role for miRNA-21 and the IL-12/STAT4 pathway in the development of allergic asthma.

[Inhibition effects of wood vinegar on Alternaria panax and Botrytis cinerea].

OBJECTIVE: Less fungicides could be used to biocontrol Alternaria panax and Botrytis cinerea, this experiment can offer preliminary theory for wood vinegar as a botanic fungicide. METHODS: The in vitro inhibition activities of wood vinegar on Alternaria panax and Botrytis cinerea were tested by using mycelial growth rate method and spore germination method. RESULTS: Inhibition of mycelium growth rate to Alternaria panax was 100% when the concentration of wood vinegar was no less than 3.0%, while the inhibition of mycelium growth rate and spore germination rate were 70.68% and 84.47%, respectively, at concentration of wood vinegar 2.25%. Inhibition of mycelium growth rate and spore germination rate to Botrytis cinerea were 100% when the concentration of wood vinegar was no less than 2.25%. CONCLUSION: Wood vinegar concentration of no less than 2.25% can be used as a biocontrol agent of Alternaria panax and Botrytis cinerea, it is useful for the further field trial.

[Secretory expression of salivary ATP diphosphohydrolase (apyrase) from Aedes albopictus in Pichia pastoris].

The gene-coding mature apyrase protein from Aedes albopictus was amplified by RT-PCR and cloned in frame with the a-factor secretion signal peptide into Pichia pastoris secreting expression vector pGAPZalpha-A resulting in the pGAPZa-A-apyrase. After being linearized by Bln I restriction enzyme, the recombinant pGAPZalpha-A-apyrase was trans-formed into Pichia pastoris GS115 by electroporation. Recombinant strains pGAPZalpha-A-apyrase/GS115 were screened on YPDS plates containing Zeocin and identified by PCR. The recombinant protein of apyrase (M(r) 60000) has been expressed in the supernatant of Pichia pastoris.

Polymorphisms of the IL-18 promoter and bronchial asthma.

To study the association of polymorphisms of the IL-18 promoter (-607C/A and -137G/C) with bronchial asthma, 120 subjects with bronchial asthma were selected as the experimental group (49 cases with bronchial asthma and allergic rhinitis as experimental group 1 and 71 cases with bronchial asthma without allergic rhinitis as experimental group 2) and 120 healthy individuals were selected as the control group. A polymerase chain reaction sequence-specific primer (PCR-SSP) was used to identify the genotypic polymorphisms between the experimental and control groups. The results revealed that the frequencies of the CC, CA and AA genotypes at -607C/A in experimental group 1 were 18.37, 40.82 and 40.82%, respectively; these frequencies were 32.39, 54.92 and 12.68%, respectively, in experimental group 2. There was a statistically significant difference in the genotype distribution between experimental groups 1 and 2 (χ²=12.81; P<0.05). The allele frequencies of genotypes C and A were 38.78 and 61.22%, respectively, in experimental group 1 and 59.86 and 40.14%, respectively, in experimental group 2. The allele frequencies at -607C/A were significantly different between experimental groups 1 and 2 (χ²=10.32; P<0.05). Frequencies of genotypes GG, GC and CC at -137C/A in experimental group 1 were 48.98, 46.94 and 4.08%, respectively, and 80.28, 14.08 and 4.08% in experimental group 2 with significant difference (χ²=15.73, P<0.05). Allele frequencies of G and C in experimental group 1 were 72.45 and 27.55%, and 87.32 and 12.68% in experimental group 2 with statistically significant difference (χ²=8.42, P<0.05). In conclusion, polymorphisms of the IL-18 gene promoter at -607C/A and -137G/C were associated with allergic rhinitis in bronchial asthma, indicating that polymorphisms of the IL-18 gene promoter at -607C/A and -137G/C differentially affect the pathogenesis of asthma and allergic rhinitis.

Association between gene polymorphism of CD14-159 (C/T) and allergic asthma.

The objective of this study was to evaluate the possible association between the CD14-159 polymorphism and adult asthma in the Chinese population. A total of 188 asthmatic patients and 60 healthy adults were enrolled in the present study, and the CD14-159 polymorphism was genotyped using the polymerase chain reaction-restriction fragment length polymorphism (PCR­RFLP) analysis. The results showed that the frequencies of CC, CT and TT genotypes were 12.2, 47.9, and 39.9%, respectively, in the asthma group, and 8.3, 50.0, and 41.7%, respectively, in healthy adults, with no statistical difference between the two groups (P>0.05). The frequencies of C and T allele were 36.2 and 63.8%, respectively, in the asthma group, 33.3 and 66.7%, respectively, in the healthy group, and no statistical difference was observed in the allele frequencies between the two groups (P>0.05). Our data suggest that the CD14-159 polymorphism is not associated with adult asthma in Chinese population.