Discriminant Analysis of Pu-Erh Tea of Different Raw Materials Based on Phytochemicals Using Chemometrics.

Pu-erh tea processed from the sun-dried green tea leaves can be divided into ancient tea (AT) and terrace tea (TT) according to the source of raw material. However, their similar appearance makes AT present low market identification, resulting in a disruption in the tea market rules of fair trade. Therefore, this study analyzed the classification by principal component analysis/hierarchical clustering analysis and conducted the discriminant model through stepwise Fisher discriminant analysis and decision tree analysis based on the contents of water extract, phenolic components, alkaloid, and amino acids, aiming to investigate whether phytochemicals coupled with chemometric analyses distinguish AT and TT. Results showed that there were good separations between AT and TT, which was caused by 16 components with significant (p < 0.05) differences. The discriminant model of AT and TT was established based on six discriminant variables including water extract, (+)-catechin, (−)-epicatechin, (−)-epigallocatechin, theacrine, and theanine. Among them, water extract comprised multiple soluble solids, representing the thickness of tea infusion. The model had good generalization capability with 100% of performance indexes according to scores of the training set and model set. In conclusion, phytochemicals coupled with chemometrics analyses are a good approach for the identification of different raw materials.

General public perceptions and attitudes toward Alzheimer's disease from five cities in China.

Alzheimer's disease (AD) is the most common type of dementia affecting the aged population worldwide, yet its social perceptions have been less studied. To investigate the perceptions and attitudes toward AD in the Chinese population, a cross-sectional face-to-face survey of 2,000 randomly selected adults was conducted in five representative cities of China. This survey focused on the fear of AD, and the relationship between this variable and each studied factor was analyzed using univariate analysis and multivariate regression analysis. In general, 76.6% of the total respondents had personal fear of developing AD, and such fear was closely related to the proximity to AD and perceived severity of AD, as well as other factors such as gender and self-perceived health. The results strongly suggested that more attention should be paid to public health education of AD, which can only be achieved with the cooperation of government, media, medical institutions, and the community so as to eliminate people's confusion about AD, relieve their psychological burden, and optimize their health-seeking behavior.

[Construction and identification of exogenous gene expression system in Lactococcus lactis].

OBJECTIVE: To construct and characterize an exogenous gene expression system in Lactococcus lactis. METHODS: PCR-based gene assembly was used to synthesize the gene sequence containing P59 promoter, USP45 signal peptide, ribosome binding site and multiple cloning site. Plasmid pBS-pu was obtained after ligation of the assembled sequence with pBluescript II SK (+), and the terminator of USP45 protein was added to construct the recombinant plasmid pNBC1000. The gene coding for Streptococcus pyogenes M6 protein was amplified and cloned into pNBC1000 to obtain the plasmid pNBC2000. To characterize the expression system, enhanced green fluorescent protein (EGFP) gene was amplified from the plasmid pEGFP-N1 and cloned into pNBC2000. Laser scanning confocal microscope was used to observe the bacteria containing pNBC2000, pNBC2000-EGFP or pBS-EGFP. RESULTS: Green fluorescence was visualized in the bacteria containing pNBC2000-EGFP, but not in the bacteria containing pNBC2000 or pBS-EGFP. CONCLUSION: The plasmids pNBC1000 and pNBC2000 containing P59 promoter, USP45 signal peptide, ribosome binding site and multiple cloning sites are successfully constructed, which are capable of expressing exogenous gene in Lactococcus lactis.