ABSTRACT
The mammalian intestinal epithelium constitutes the largest barrier against the external environment and makes flexible responses to various types of stimuli. Epithelial cells are fast-renewed to counteract constant damage and disrupted barrier function to maintain their integrity. The homeostatic repair and regeneration of the intestinal epithelium are governed by the Lgr5+ intestinal stem cells (ISCs) located at the base of crypts, which fuel rapid renewal and give rise to the different epithelial cell types. Protracted biological and physicochemical stress may challenge epithelial integrity and the function of ISCs. The field of ISCs is thus of interest for complete mucosal healing, given its relevance to diseases of intestinal injury and inflammation such as inflammatory bowel diseases. Here, we review the current understanding of the signals and mechanisms that control homeostasis and regeneration of the intestinal epithelium. We focus on recent insights into the intrinsic and extrinsic elements involved in the process of intestinal homeostasis, injury, and repair, which fine-tune the balance between self-renewal and cell fate specification in ISCs. Deciphering the regulatory machinery that modulates stem cell fate would aid in the development of novel therapeutics that facilitate mucosal healing and restore epithelial barrier function.
ABSTRACT
OBJECTIVE: To explore the environmental risk factors of different categories of congenital heart defects (CHD) and provide evidence for further risk factors and prevention research of CHD phenotypes. METHODS: Data of Guangdong CHD Register Study from 2004 to 2012 were used. In the study, 3 038 CHD cases and 3 038 paired controls from 34 hospitals distributed in 17 cities were registered and related information were collected using uniform, and structured questionnaires. All the CHD phenotypes were coded according to the International Classification of Diseases 10th Revision (ICD-10) and classified into 6 categories according to their pathological features. Univariate analyses were adopted to filter potential risk factors for each category of CHD. Then multivariate conditional Logistic regression was used to calculate the odds ratios of the risk factors for each category of CHD. RESULTS: The risk factors for left-to-right shunt CHD included low (OR=2.63, 95%CI:2.04-3.39) or over birth weight (OR=2.21, 95%CI: 1.47-3.32), premature delivery (OR=1.95, 95%CI: 1.53-2.49), polyembryony (OR=1.99, 95%CI: 1.22-3.26), maternal low education, mother as factory worker (OR=1.62, 95%CI: 1.32-1.98), parity≥2 (OR=1.38, 95%CI: 1.13-1.69), maternal abnormal reproduction history (OR=2.29, 95%CI: 1.75-3.01), fever (OR=2.38, 95%CI: 1.26-4.48), virus infection (OR=1.80, 95%CI: 1.29-2.51), medicine usage (OR=1.73, 95%CI: 1.11-2.69), passive smoking (OR=1.69, 95%CI: 1.26-2.29), chemical agent contact (OR=8.71, 95%CI: 2.33-32.58), living in newly decorated houses (OR=2.56, 95%CI: 1.60-4.09) or room close to the main road (OR=1.40, 95%CI: 1.14-1.72) in the first 3 months of pregnancy and father as factory worker (OR=1.46, 95%CI: 1.23-1.73). The risk factors for pulmonary outflow tract obstruction CHD included low (OR=5.98, 95%CI: 2.88-12.44) or over birth weight (OR=6.56, 95%CI:1.19-36.26), maternal low education, parity≥2 (OR=2.08, 95%CI: 1.03-4.22), virus infection in the first 3 months of pregnancy (OR=4.30, 95%CI: 1.27-13.45). The risk factors for left ventricular outflow tract obstruction CHD included father as factory worker (OR=6.01, 95%CI:1.05-34.59). The risk factors for transposition of the great arteries included low birth weight (OR=12.93, 95%CI:1.14-146.26), maternal low education, mother as factory worker (OR=3.69, 95%CI:1.53-8.91). The risk factors for conditions with intra cardiac mixing of oxygenated and deoxygenated blood included parity=2 (OR=3.45, 95%CI: 1.42-8.38). The risk factors for other CHD included over birth weight (OR=4.87, 95%CI: 1.19-19.94), maternal abnormal reproduction history (OR=2.96, 95%CI: 1.14-7.68), virus infection (OR=4.92, 95%CI: 1.56-15.47), medicine usage (OR=4.90, 95%CI: 1.22-19.77) or passive smoking (OR=10.31, 95%CI: 1.25-85.05) in the first 3 months of pregnancy. CONCLUSION: The environmental risk factors were discrepant among different categories of CHD. Further risk factors study of CHD phenotypes should be performed specially. To prevent CHD, attention should be paid to the risk factors which are related to multi or complex categories of CHD.
