ABSTRACT
Objective:To explore the role ofDNA methyltransferase 1 (DNMT1) in mouse skin aging.Methods:Epidermal conditional K14 Cre-mediated DNA methyltransferase 1 (DNMT1) knockout mice (Mut group,n=4) and the littermate normal mice with the same age (WT group) n=4) were used in this study.HE staining was used to detect the pathological changes of skin;the changes of number in the dermal elastic fibers were detected by Gomori aldehyde fuchsin staining,the number of 5-bromo-2-deoxyuridine (BrdU)-labeled transit amplifying cells (TAC) in epidermis were detected by immunohistochemical staining;the number of chlorodeoxyuridine (CldU)-labelretaining cells (LRC) in epidermis were detected by immunofluorescent staining.Results:Compared with the WT group,the skin showed premature aging symptoms in the Mut group concomitant with the decreased epidermal thickness as well as the number of dermal collagen fibers,while the increased dermal elastic fiber fracture.Compared with the WT group,the number of TAC in the epidermis was significantly increased (P＜0.05),and the number of LRC was significantly decreased (P＜0.05) in the Mut group.Conclusion:The phenotype of skin premature aging in epidermal stem cell conditional DNMT1-knockout mice suggests an important role of DNMT 1 in skin aging.
ABSTRACT
This study was aimed to assess the potential of Dioscorea [yam] leaves as a source of antioxidants. Microwave-assisted extraction [MAE] process was used to prepare the extracts. The phenolic compounds in Dioscorea leaves extracts were analyzed by HPLC-DAD-ESI-MS/MS method and the contents of major compounds were determined. Results indicated that a total of 17 phenolic compounds were separated identified by means of UV and mass spectra compared with authentic reference substances and/or reported values in the literature. The main phenolic compound was rosmarinic acid and its highest amount was found in Dioscorea glabra Roxb. leaves [22.31+/-1.33 mg/g DW]. Rutin was the dominant flavonoid followed by quercetin which highest amount was found in Dioscorea alata leaves [8.66+/-0.29 mg/g DW]. Antioxidant activity of the extracts was estimated by the use of DPPH and ABTS assays. Both kinds of leaves exhibited satisfied antioxidant capacity which was correlated with phenolic contents. In the cytoprotective effect on HUVECs viability assay, Dioscorea glabra Roxb. leaves extract was found to be more active than that of Dioscorea alata against H2O2-induced oxidative stress. Our findings support the promising role of Dioscorea leaves that can be used as an interesting source of phenolic antioxidants
ABSTRACT
This paper discussed constructing the preventive medicine experiment demonstration teaching center,promoting the reform and innovation on nutrition and food hygiene,and put forward such teaching reformation and methods as innovative teaching idea for the specialty to keep up with time and the combination of modularization and systematization.
ABSTRACT
To elevate the teaching effect of clinical nutriology in adult education and be satisfied with clinic and society. The exploration is made of choosing textbook and refining teaching material,adjusting teaching methods,paying attention to cultivating practice skills and reform on exam. The results of scores of clinical nutriology and practice skills are good.