Objective:To study the inhibitory effects and mechanism of Armeniacae Semen Amarum alcohol extract in melanogenesis in zebrafish embryos.Methods:48 HPF healthy zebrafish embryos were randomly divided into blank control group, arbutin group, high-, medium- and low-dosage groups. The blank control group was added with 6 ml embryo culture medium, the arbutin group was added with 8 000 μg/ml arbutin solution 6 ml, and the high-, medium- and low-dosage groups were added with 2 925, 1 950 and 1 300 μg/ml Armeniacae Semen Amarum alcohol extract, respectively. After 24 hours of intervention, the melanin area of zebrafish embryos was observed by stereomicroscope, and the inhibition rate of ethanol extract of bitter almond on tyrosinase (TYR) activity and melanin content in zebrafish embryos were detected by spectrophotometry; the antioxidant activity was evaluated by DPPH radical scavenging capacity, ABTS radical scavenging capacity and CAT activity. RT-qPCR was used to detect the mRNA levels of MITF, Tyr and TYRP2 in zebrafish embryos.Results:Compared with the arbutin group, the low-, medium-, and high-dosage groups showed an increase in melanin area ( P<0.01 or P<0.05), a decrease in TYR activity and melanin content inhibition rate ( P<0.01), and IC50 values for DPPH and ABTS free radical scavenging rates of 23.636 and 3.195 mg/ml, respectively. The CAT activity increased in the medium- and high-dosage groups ( P<0.05 or P<0.01), while the mRNA levels of TYR and MITF decreased in the low-, medium-, and high-dosage groups ( P<0.01). Conclusion:Armeniacae Semen Amarum alcohol extract can effectively inhibit the production of melanin in zebrafish embryos, and its mechanism may be closely related to TYR activity and MITF related signaling pathway.

Objective:Analyze the mediating and moderating effects of the relationship between food intake and blood glucose levels.Methods:This study uses data from the China Health and Nutrition Survey project in the survey 2018, involving 11 043 adults aged 18 years or older, who have complete dietary data, waist circumference (WC), glycated hemoglobin A1c (HbA1c) indicators, and other key variables. Food consumption data was gathered via three consecutive 24-hour dietary recalls and weighing accounting method, which included two weekdays and one weekend day. The average daily intake of various foods and total energy intake were calculated. The mediation effect and moderation effect analysis were conducted using simple mediation models, direct moderation effect models, and moderated mediation analysis theoretical models. The confidence interval method (bootstrap method) was performed for testing and analysis.Results:A total of 4 951 males and 6 092 females were included in the stratified analysis by gender. The mediating effects on the rice, wheat, and red meat→WC→HbA1c were all statistically significant in males. The standardized coefficients were -0.009 ( P<0.001), 0.013 ( P<0.001), and -0.005 ( P=0.008), respectively. In females, the mediating effect on the wheat→WC→HbA1c was statistically significant, and the standardized coefficient was 0.017 ( P<0.001); the impact of red meat intake on HbA1c is negatively regulated by the intake of dark vegetables, with a direct moderating effect; the standardized coefficient of the interaction term between red meat and dark vegetables was -0.024 ( P=0.008). Dark vegetables have a moderated mediator on the pathway from rice to WC and HbA1c ( a3b1=-0.003, P=0.041) in males. The mediating effect of WC is negatively regulated by the intake of dark vegetables (mediation effect difference U1/-1=-0.006, P=0.048). Dark vegetables showed a moderated mediator on the pathway from wheat to WC and HbA1c ( a3b1=-0.004, P=0.045) in females. The mediating effect of WC is negatively regulated by the intake of dark vegetables (mediation effect difference U1/-1=-0.009, P=0.049). Conclusions:Changes in WC indicators caused by rice, wheat, and red meat intake. WC could mediate between rice, wheat, red meat, and HbA1c. Dark vegetables directly or indirectly regulate HbA1c levels by interacting with rice, wheat, and red meat.

Objective: To understand the internship of students majoring in preventive medicine in 6 colleges and universities in China, and provide reference suggestions for the improvement of internship arrangement. Methods: By using the method of combined clustering and convenient sampling, the fifth grades students majoring in preventive medicine in six universities in the eastern, central and western China were surveyed by using questionnaires to collect the information of their attitudes (to) and suggestions for clinical and public health internships. Results: A total of 596 students were surveyed. In terms of the benefits of clinical internship and public health internship, students who thought that the internship was fruitful accounted for >88%, and more students thought that reform is needed in clinical internship compared with public health internship. In clinical internship, the students through that the time arrangement was not appropriate enough (95, 39.58%), the content should be more detailed and in-depth (73, 30.42%) and the content did not conform to the professional direction (54, 22.50%). In public health internship, the students thought that the time arrangement was not appropriate (77, 45.56%), the content should be more detailed and standardized (65, 38.46%) and the types of internship bases should be more diversified (20, 11.83%). Conclusions The undergraduates majoring in preventive medicine felt to be benefited from clinical practice and public health internships and thought they are of necessity. At the same time, there are still many problems which needs to be improved in the two types of internships. It is necessary to make joint efforts from students, teachers, colleges and practice bases to promote the continuous improvement of undergraduate internship.