Research progress in oxidative stress induced by antibiotics in bacteria / 中华微生物学和免疫学杂志

Antibiotics can not only combine with specific targets, but also induce a cascade of re-active oxygen species ( ROS) in bacteria. Antioxidant defense system plays an important role in scavenging ROS and repairing injury against oxidative stress. However, the mechanism of ROS accumulation in bacteria and the action of ROS are very complicated. Therefore, this paper reviewed the mechanisms of bacterial re-sponding to oxidative stress in the existence of antibiotics. In addition, we analyzed the main problems lying in the current study and the issues needing further consideration.

Effects of bone marrow mesenchymal stem cell conditioned medium with and without inflammatory activation on radiation-induced intestinal injury / 中国组织工程研究

BACKGROUND:Conditioned medium from mesenchymal stem cels (MSC-CM) may represent a promising alternative to MSCs transplantation. Previous studies have shown that inflammatory activation can strengthen the multiple biological potencies of MSCs; however, normal MSCs with insufficiency of immunocompetence and migration ability are not effective for tissue damage repair. OBJECTIVE:To investigate differential effects of MSC-CM with and without inflammatory activation on radiation-induced intestinal injury.METHODS:MSCs from the bone marrow of SD rats were separated, cultured and identified, and then co-cultured with non-irradiated IEC-6 or irradiated IEC-6 in a transwel system for 24 hours. Then, MSCs with inflammatory activation were cultured alone for another 48 hours. After that, the supernatant was colected as non-activated MSC-CM (MSC-CMNOR) and MSC-CM under radiation-induced inflammatory condition (MSC-CMIR). Rats were exposed to 14 Gy whole abdominal irradiation and randomly divided into four groups: control group, radiation injury group (DMEM/F12), MSC-CMNOR group and MSC-CMIR group. Continuous administration was givenvia tail vein and intraperitoneal implantation of Alzet microosmotic pumps. Intestinal samples were colected at 1, 3, 7 days after radiation for analysis of short circuit variation, at 3 days after radiation for analysis of intestinal epithelium ultrastructure, and at 1, 3, 5, 7, 14 days after radiation for histological observation of the intestinal epithelium using hematoxylin-eosin staining. Blood samples were colected at 1, 3, 7 days after radiation for analysis of serum xylose levels. In addition, the survival state and survival time of rats were observed and recorded. RESULTS AND CONCLUSION: The short circuit variation responding to electrical field stimulation was significantly reduced at al frequencies, but it was significantly improved in the MSC-CMIR group. Similarly, the intestinal absorption (serum xylose levels) was also significantly impaired by irradiation, but improved by delivery of MSC-CMIR (P < 0.05). At 3 days after MSC-CMIR infusion, the intestinal epithelium exhibited an increase in crypt size and vilous length (P < 0.05). Under the electron microscope, a reduction in intestinal microvili and open tight junctions in irradiated intestinal epithelium was found, and the intestine from rats treated with MSC-CMIR had more obvious tight junctions. In addition, treatment with MSC-CMIR dramaticaly improved the survival rate and mean survival time of irradiated rats as compared to those treated with DMEM/F12 or MSC-CMNOR (P < 0.05). Taken together, the present study demonstrated that MSC-CMIR , but not non-activated MSC-CM, improves the structural and functional restoration of the smal intestine after radiation-induced intestinal injury.

The clinical value of capsule endoscopy image screening system / 中华消化内镜杂志

ObjectiveTo evaluate the clinical value of capsule endoscopy (CE) image screening system developed by our group.MethodsBetween March 2011 and June 2011,50 patients (29 males and 21 females with a mean age of 45.7(45.7 ± 4.1 ) ) underwent CE in our department.CE images were reviewed,and processed by the screening system at the rate of 50％,60％,70％,80％ and 90％,respectively.After reviewing the remaining and the deleted frames,the endoscopists calculated the remaining rate of the lesions by recording the number of lesions of all patients and the number of remaining lesions.The procedure time and the total number of the frames of each case were also recorded.ResultsA total of 39 patients of 50 had lesions and the detection rate was 78％.91 lesions were detected in the 39 patients,most of whom had more than 2 lesions.When the prescribed deletion rate was less than or equal to 60％,the lesion remaining rate reached 100％,with a mean frames of the cases of 46 242,and the mean processing time of 15.62 min.ConclusionWith all the lesions remained,the system can delete 60％ similar frames in a very short time,which greatly reduces the diagnosis time and workload for endoscopist,and improves the efficiency of capsule endoscopy.

Risk factors for false negative diagnosis of obscure gastrointestinal bleeding by capsule endoscopy / 中华消化内镜杂志

ObjectiveTo analyze the risk factors for false negative diagnosis of obscure gastrointestinal bleeding (OGIB) by capsule endoscopy.MethodsA total of 133 OGIB inpatients,104 in true positive group and 29 in false negativc group,were reviewed.The features of demography,diseases and capsule endoscopy were collected and then analyzed,which included 10 variables like age,sex,time of bleeding,diseases accompanied,type and location of the disease,hemoglobin concentration,transit time of CE,quality of CE pictures and type of purgative agents.All data were analyzed with t test,and all the enumeration data were analyzed with chi square test.Logistic regression was used to analyze the correlation between the factors and results of diagnosis.ResultsAge ( t =2.095,P =0.038 ),concentration of hemoglobin ( t =2.143,P=0.034),type (X2 =20.222,P ＜0.001) and location (X2 =33.732,P ＜0.001) of the diseases,image quality of the CE (X2 =9.219,P =0.002 ) and the type of purgative agents (X2 =6.999,P =0.024) were found to have statistical differences between the two groups.Chi-square and partition Chi-square test revealed the occurrence of civerticulosis and lesion location,i.e.lower ileum and ileumcecum,were of statistical difference between the two groups (X2 =22.233,P ＜ 0.001 and x2 =24.412,P ＜ 0.001 ).Univariate logistic regression showed diverticulosis ( OR =0.102,P ＜0.001 ),lower bowel diseases ( OR =0.110,P ＜0.001 ),poor quality of CE pictures ( OR =0.258,P =0.004 ) and the use of sodium phosphate agent ( OR =0.367,P =0.027) were risk factors for false negative diagnosis,while older age facilitated diagnosis ( OR =1.024,P =0.041 ).However,multivariate logistic regression showed no statistic significance in type of purgative agent ( P =0.05 ) or the concentration of hemoglobin ( P =0.394).Furthermore,elder age facilitated positive diagnosis ( OR =1.031,P =0.032),while diverticulosis ( OR =0.118,P =0.001 ),lower bowel diseases ( OR =0.145,P =0.001 ) and poor quality of CE pictures ( OR =0.245,P =0.016) were correlated with higher probability of false negative diagnosis.ConclusionAge,disease type,disease location and image quality exert great influence on CE diagnosis.Diverticulosis,lower location of the diseases and poor CE image quality are risk factors for false negative diagnosis.