Tight junctions(TJs) are the primary junctions between intestinal epithelia.TJs serve as the maintenance of epithelial cell polarity and the rate-limiting barrier to passive movement of hydrophilic solutes across intestinal epithelia.It plays an important role in maintaining integral intestinal epithelia,protecting intestinal barrier and preventing bacterial endotoxin and other toxin into body.This review is about biological functions,molecular regulating mechanisms of intestinal epithelial tight junctions and some factors affecting on them.

Colorectal cancer (CRC) is a malignant digestive tract tumor resulted from genetic and environmental factors and can be accompanied by a series of gene mutations.The etiology of CRC,particularly the role of gut microbiota imbalance,has became a hot research topic along with the increase of its prevalance.In this article,we elucidate the potential roles and mechanisms of streptococcus gallolyticus,fusobacterium,Escherichia coli,Bacteroides fragilis,and helicobacter wlori in the development of CRC,with an attempt to further understand the functions of microbiota,search for possible specific carcinogenic strains,and improve the management of CRC.

Human guts harbor abundant microbes that regulate many aspects of host physiology.However,bacterial imbalance or dysbiosis in the gut due to the dietary or environmental changes may cause colorectal cancer (CRC).Therefore,it is theoretically and clinically important to explore the correlation between possible carcinogenic bacteria and CRC and thus reduce CRC incidence by regulating intestinal microecological balance through the application of microecological preparations.

Insulin resistance(IR) develops following major injury to the body, including serious trauma, surgical infection and burn. Metabolic disorders due to IR have a serious impact on energy production and attenuate body capacity of anti-infection and anti-shock. Therefore, the research about the mechanism of post-traumatic insulin resistance will be beneficial to improving patients' metabolism situation.

Objective: To investigate the influences of IGF-1 on the stress hormone,GLUT-4 and its mRNA expression.Methods: The SD rats with abdominal infection established by cecal ligation and perforation method were randomly divided into three groups: pyaemic group(n=10),parenteral nutrition group(PN group,n=10) and IGF-1 Group(n=10).10 healthy rats was used as the normal group(n=10).On the sixth day,blood was sampled to determine the level of glucose,insulin,glucagon and IGF-1.The expressions of GLUT-4 and its mRNA in muscle were detected by immuno-histochemistry and Real-Time PCR methods.Results: The plasma levels of glucose,insulin and glucagon in the IGF-1 group were significantly lower than those in the pyaemic group and PN group(P

Objective:To investigate the influences of IGF-1 on the stress homone,InsR?、? gene expression and protein content in pyaemia rats.Methods:SD rats with abdominal infection models established by cecal ligation and perforation method were randomly divided into three groups: pyaemic group(n=10),parenteral nutrition group(PN group,n=10) and IGF-1 Group (n=10),and 10 SD rats were used as normal group(n=10).On the sixth day,Vena Cava blood was sampled to determine the level of glucose,insulin,glucagon,and IGF-1.In addition,the expression of the InsR?、? in liver and muscle were detected by immunohistochemistry and Real-Time PCR methods.Results:The plasma glucose,insulin,glucagon in the IGF-1 group were significantly lower than that of the pyaemic group and PN group(P

Objective To study the effects of glutamine (Gln) combined with growth hormone (GH) on the levels of cytokine (TNF-?, IL-1, IL-6), coritsol and amino acid metabolism in septic rats. Methods Ten out of 79 SD rats were randomly collected as the control group. Thirty of 69 septic SD rats, which were made by cecal ligation and perforation (CLP) method and were given parenteral nutrition (PN) lived to day 6. They were also randomly divided into three groups as follows: septic group (n=10), parenteral supplemented glutamine group (Gln group, n=10), and Gln combined with GH (Gln+GH group, n=10). On the 6th day, blood drew from portal veins of the dead rats was used to detect the levels of TNF-?, IL-1, IL-6 and cortisol by ELISA. The plasma concentrations of free amino acids were determined by amino acid auto-analyzer. The muscle tissue of extensor digitorum longus was used to determine 3-methyl-histidine (3-MH) by high performance liquid chromatographic (HPLC). Results Except for the control group, most rats developed celiac abscess, hepatic abscess and pulmonary infection. The serum levels of TNF-?, IL-1, IL-6 and cortisol were significantly higher in the septic group than those of the other three groups, and they were significantly lower in the Gln+GH group than those of the Gln group, P

Objective To study the protective effect of glutamine on the intestinal mucosal antioxidation in endotoxemic rats. Methods　Twenty-eight male Wistar rats were randomly divided into three groups, group A:parenteral nutrition supplemented with glutamine, group B:TPN without glutamine,and group C:normal control. Endotoxemia was induced by continous intravenous infusion of lipopolysaccharide(LPS) at a dose of 2 mg/kg per day throughout the 5-day study period. The mucosal protein、DNA、ATP、SOD、MDA、GSH、sIgA were determined. Results The mucosal protein、DNA、ATP、SOD、GSH and sIgA content in endotoxic rats were markedly decreased, MDA was increased as compared with normal control(P＜0.05). The former indices in group A were improved and MDA content was decreased as compared with group B(P＜0.05). Conclusion　Glutamine can improve gut energy metabolism, decrease the extent of mucosal injury of free radicals, and give an protective effect on the mucosal probably by increasing GSH.

Objective To investigate the effect of enteral and parenteral nutrition on gut microecology in rats with abdominal infection. Methods Fourteen Sprague-Dawley (SD) model rats of abdominal infection, which had survived for more than 6 days were divided into two groups: PN group ( n =7) and PN+EN group ( n =7) via jejunostomy and jugular vein respectively for another 5 days. The nutrition support in the two groups was isonitrogen and isocaloric. At sacrifice on the sixth day, occludin and IgA level in plasma cells of intestine epithelium of the gut were measured by immunohistochemistry. Vena cava blood and homogenated tissue of liver, lung and mesenteric lymph nodes were cultured to determine bacterial translocations, and portal vein blood was tested for endotoxin. Results The expression of occludin and IgA in the small and large intestine in PN+EN group were stronger than PN group ( P

Objectives:To evaluate the effect of early enteral nutrition(EEN) on the structure and function of the gut, the bacterial and endotoxin translocation. Methods:SAP model was induced by injecting 1 ml/kg of combined solution of 5% sodium taurocholate and trypsin into the pancreas via pancreatic duct.15 dogs were divided into PN group and EEN group.Systemic plasma endotoxin levels was quantified.Both portal and systemic blood sample were obtained before and 1?4?7 d following SAP,and cultured for aerobic as well as anaerobic bacterial growth.Specimens of tissue from mesentery lymph nodes,lung and pulmonary portal nodes and pancreas were removed,weighed and homogenized at the 7th day. Results:The levels of systemic plasma endotoxin and the magnitude of bacterial translocation to the portal and cycle blood and distant organs were significantly reduced the protein and DNA content of the small intestine and colon increased,and the height of the villi and the thickness of mucosa and whole bowel wall of the intestinel and colon improved in EEN group as compared with those in PN group. Conclusions:We conclude that EEN can improve gut metabolism,decrease the extent of mucosal atrophy,and assist in the maintenance of the mucosal barrier function.It is effective touse EEN in severe acute pancreatitis.