[Application of target trail emulation in real world: a case study of effect of statins on mortality in diabetes patients].

Target trail emulation is an observational research method, which can use real-world data (such as observational data and historical data) to carry out research design according to the design principles of randomized controlled trials (RCT) when RCT cannot be carried out. The intervention group and the control group were classified by simulating random grouping. Finally a high-reliable conclusion similar to RCT can be obtained. This paper summarizes the basic concepts and application process of target trail emulation based on the effect of statins on the prognosis of myocardial infarction in diabetic patients to provide reference for the application of this method in real world.

[Application of LASSO and its extended method in variable selection of regression analysis].

Multicollinearity is an important issue affecting the results of regression analysis. LASSO developed in recent years has great advantages in selecting explanatory variables, processing high-dimensional data, and solving multicollinearity problems. This method adds a penalty term to the model estimation, which can compress the regression coefficients of some unnecessary variables to zero and then remove them from the model to achieve the purpose of variable screening. This paper focuses on the LASSO method and compares it with optimal subsets, ridge regression, adaptive LASSO, and elastic net results. It is found that both LASSO and adaptive LASSO have good performance in solving independent variable multicollinearity problems and enhancing model interpretation and prediction accuracy.

[Application of regression discontinuity design in epidemiological research].

Regression discontinuity design (RDD) is a rigorous quasi-experimental method. Based on the randomness of the distribution of samples around the critical value, the data on both sides are used for regression respectively, so as to avoid the interference of potential confounding factors and provide strong evidence for the inference of causal correlation. This study introduces the RDD and its research progress, and expounds its application in detail combined with cases, in order to provide reference for the application of RDD in epidemiological research.

[Visualization of transcriptome data].

As an important method to study the phenotype and function of organisms, transcriptome has become one of hot topics in current research. The transcriptomics research usually accompanies with massive data. With the increase of the amount of data, the rules and features hidden in it are not easy to be found. Transforming big data into visual graphics is the most undoubtedly intuitive way to display the hidden information of big data. Several graphs commonly used in transcriptome study were introduced in this paper, such as Venn diagram, heat map, principal component analysis scatter plot, enrichment analysis plot, and time series analysis plot, in order to help readers to choose suitable graphics in future studies.

[Visualization of frequency distribution].

Statistical graph, as a useful tool of data visualization, plays a crucial role in the statistical description. This paper mainly introduces several common statistical charts, their characteristics, practical examples and so on for frequency distribution, including qualitative variable and quantitative variable, in order to provide application reference for readers.

[Using the sequenced sample cluster analysis to study the body mass index distribution characteristics of adults in different age groups and genders].

Objective: To explore the characteristics of distribution on Chinese adult body mass index (BMI) in different age groups and genders and to provide reference related to obesity and related chronic diseases. Methods: Data from the China Health and Nutrition Survey in 2009 were used. Sequential sample cluster method was used to analyze the characteristics of BMI distribution in different age groups and genders by SAS. Results: Our results showed that the adult BMI in China should be divided into 3 groups according to their age, as 20 to 40 years old, 40 to 65 years old, and> 65 years old, in females or in total when grouped by difference of 5 years. For groupings in male, the three groups should be as 20 to 40, 40 to 60 years old and>60 years old. There were differences on distribution between the male and female groups. When grouped by difference of 10 years, all of the clusters for male, female and total groups as 20-40, 40-60 and>60 years old, became similar for the three classes, respectively, with no differences of distribution between gender, suggesting that the 5-years grouping was more accurate than the 10-years one, and BMI showing gender differences. Conclusions: BMI of the Chinese adults should be divided into 3 categories according to the characteristics of their age. Our results showed that BMI was increasing with age in youths and adolescents, remained unchanged in the middle-aged but decreasing in the elderly.

Relationship between apoptosis and proliferation in granulosa and theca cells of cystic follicles in sows.

To investigate the causes of the occurrence and persistence of porcine cystic follicles, we evaluated the apoptosis and proliferation of follicular cells in these cysts. Apoptotic frequencies were examined by TUNEL assay and the expression of apoptosis regulators (XIAP, bax, bc1-2 and caspase-3) by immunohistochemistry, Western blotting and real-time quantitative PCR; cell proliferation activity was evaluated by PCNA immunohistochemistry and proliferation of in vitro cultured granulosa and theca cells. The low apoptotic frequency and weak proliferative activity were found in cystic follicles. Low frequency of apoptosis might be associated with decreased amounts of apoptotic-related factors (bax and caspase-3) and increased amounts of anti-apoptotic factors (XIAP and bcl-2) in cystic follicles. Significantly lower proliferation activity was detected in granulosa and theca cells from cystic follicles, and lesser PCNA-positive cells were found in cystic follicles. Our results indicate that the programmed cell death and cell proliferation system were altered in cystic follicles. The disorder between apoptosis and proliferation was responsible for maintaining a static condition without degeneration, which leads to the long-term persistence of follicles. These findings provide important novel insights into the pathogenesis of follicular cysts in sows.

Comparative proteomic analysis of follicular fluids from normal and cystic follicles in sows.

Follicular fluid (FF) includes various biologically active proteins which can affect follicular growth and maturation. Certain proteins could reflect the physiological and pathological status of follicles. The aim of the present study was to explore the key proteins associated with pathogenesis of follicular cysts, some of which may be candidate biomarkers for the condition. We analysed the proteomes of FF from small, medium, large and cystic follicles by two-dimensional electrophoresis (2-DE) combined with mass spectrometry (MS). The protein components in FF were found to be significantly different among groups; about 300 proteins spots in each group were examined, and 32 differentially expressed proteins were identified from different groups. To further reveal the source of identified proteins, transcripts encoding two of these, transferrin and RBP-4, were detected in granulosa cells (GCs) by RT-PCR, as well as the proteins were detected in 24 h culture media of GCs by ELISA. High levels of RBP-4 were examined in FF of cystic follicles by 2-DE analysis, which were significantly different to those in large follicles (p < 0.05). In conclusion, the study enriches our understanding of the proteins of FF; RBP-4 and transferrin originate from passive transfer and follicular synthesized secretion, and RBP-4 might be a candidate biomarker for porcine follicular cysts. Combined with histological studies, these results further suggest that changes of the type and quantity of proteins in FF might be attributed to an abnormal metabolism of follicular cells and structure of follicular wall in cystic follicles. Our findings will contribute to further insight into the pathogenesis of follicular cysts.