Up-regulation of NHE8 by somatostatin ameliorates the diarrhea symptom in infectious colitis mice model

Xuelian Lei,Lin Cai,Xiao Li,Hua Xu,Chong Geng,Chunhui Wang 대한약리학회 2018 The Korean Journal of Physiology & Pharmacology Vol.22 No.3

Na+/H+ exchangers (NHEs) have been shown to be involved in regulating cell volume and maintaining fluid and electrolyte homeostasis. Pooled evidences have suggested that loss of Na+/H+ exchanger isoform 8 (NHE8) impairs intestinal mucosa. Whether NHE8 participates in the pathology of infectious colitis is still unknown. Our previous study demonstrated that somatostatin (SST) could stimulate the expression of intestinal NHE8 so as to facilitate Na+ absorption under normal condition. This study further explored whether NHE8 participates in the pathological processes of infectious colitis and the effects of SST on intestinal NHE8 expression in the setting of infectious colitis. Our data showed that NHE8 expression was reduced in Citrobacter rodentium (CR) infected mice. Up-regulation of NHE8 improved diarrhea symptom and mucosal damage induced by CR. In vitro, a similar observation was also seen in Enteropathogenic E. coli (EPEC) infected Caco-2 cells. Seglitide, a SST receptor (SSTR) 2 agonist, partly reversed the inhibiting action of EPEC on NHE8 expression, but SSTR5 agonist (L-817,818) had no effect on the expression of NHE8. Moreover, SST blocked the phosphorylation of p38 in EPEC-infected Caco-2 cells. Taken together, these results suggest that enhancement of intestinal NHE8 expression by SST could ameliorate the symptoms of mice with infectious colitis.

Up-regulation of NHE8 by somatostatin ameliorates the diarrhea symptom in infectious colitis mice model

Lei, Xuelian,Cai, Lin,Li, Xiao,Xu, Hua,Geng, Chong,Wang, Chunhui The Korean Society of Pharmacology 2018 The Korean Journal of Physiology & Pharmacology Vol.22 No.3

$Na^+/H^+$ exchangers (NHEs) have been shown to be involved in regulating cell volume and maintaining fluid and electrolyte homeostasis. Pooled evidences have suggested that loss of $Na^+/H^+$ exchanger isoform 8 (NHE8) impairs intestinal mucosa. Whether NHE8 participates in the pathology of infectious colitis is still unknown. Our previous study demonstrated that somatostatin (SST) could stimulate the expression of intestinal NHE8 so as to facilitate $Na^+$ absorption under normal condition. This study further explored whether NHE8 participates in the pathological processes of infectious colitis and the effects of SST on intestinal NHE8 expression in the setting of infectious colitis. Our data showed that NHE8 expression was reduced in Citrobacter rodentium (CR) infected mice. Up-regulation of NHE8 improved diarrhea symptom and mucosal damage induced by CR. In vitro, a similar observation was also seen in Enteropathogenic E. coli (EPEC) infected Caco-2 cells. Seglitide, a SST receptor (SSTR) 2 agonist, partly reversed the inhibiting action of EPEC on NHE8 expression, but SSTR5 agonist (L-817,818) had no effect on the expression of NHE8. Moreover, SST blocked the phosphorylation of p38 in EPEC-infected Caco-2 cells. Taken together, these results suggest that enhancement of intestinal NHE8 expression by SST could ameliorate the symptoms of mice with infectious colitis.

The corrosion behaviour of alloy 690 tube in simulated PWR secondary water with the effect of solid diffusing hydrogen

Chen, Junjie,Lu, Zhanpeng,Meng, Fanjiang,Xu, Xuelian,Xiao, Qian,Kim, Ho-Sub,Jang, Changheui Elsevier 2019 JOURNAL OF NUCLEAR MATERIALS Vol.517 No.-

<P><B>Abstract</B></P> <P>High-temperature water corrosion tests were performed to investigate the corrosion behaviors of Alloy 690 TT in simulated PWR secondary water with gaseous hydrogen permeation condition. Double-layer oxide films formed on hydrogen-free and hydrogen-permeating specimens. The thickness of a Cr-rich inner oxide film on the hydrogen-free specimens has no obvious difference from the hydrogen-permeating ones. For hydrogen-free specimens, the outer oxide films were Fe and Ni enriched spinel-type oxide particles. For hydrogen-permeating specimens, outer oxide films were sheet-like or needle-like Cr-rich chromia-type oxides. In summary, the solid diffusing hydrogen affected the morphology and composition of outer oxides.</P> <P><B>Highlights</B></P> <P> <UL> <LI> High temperature water corrosion test was performed in hydrogen permeation condition. </LI> <LI> The thickness of Cr-rich inner films has no obvious change by hydrogen permeation. </LI> <LI> Sheet-like outer oxides on hydrogen-permeating samples unlike hydrogen-free ones. </LI> <LI> Fe and Ni-rich spinel-type outer oxide films formed on hydrogen-free specimens. </LI> <LI> Cr-rich chromia-type outer oxide films formed on hydrogen-permeating specimens. </LI> </UL> </P>

An Investigation of Responsibility and Learner Autonomy in a Sino-British EAP Program in China

Wen-Cheng Hsu,Ling Xia,Xuelian Xu 아시아테플 2019 The Journal of Asia TEFL Vol.16 No.1

Learner autonomy has become a universally acknowledged benign notion and exercised in all levels of education, especially in tertiary settings, although some doubts have been cast on its suitability in teacher-dependent contexts. Learner autonomy entails capacity to take on responsibility for ones’ own learning. This study aims to investigate students’ perceptions of their own responsibility and their teachers’, and then evaluate students’ autonomy in English learning in an EAP curriculum in a Sino-British university in China. To these aims, a 30-item questionnaire was compiled to administer to 276 year 1 and year 2 students, and T-test and one-way ANOVA were used to analyze the data. It was found that students in this Sino-British context perceived themselves to assume more responsibility for their own learning compared to their Chinese counterparts, but teachers had more responsibility to stimulate their learning inside the classroom. The degree of autonomy increased accordingly by students’ language proficiency level. Female students assumed more responsibility than male students while the latter were more autonomous than the former. Although students had a good understanding of course aims, they had low awareness of setting goals and plans. These findings have implications for promoting autonomy in tertiary settings in this specific context, as well as in other tertiary settings.

Mean Nocturnal Baseline Impedance and Post-reflux Swallow-induced Peristaltic Wave Index Could Identify Gastroesophageal Reflux Disease but pH-Impedance Metrics Alone Might Not Correlate With Proton Pump Inhibitor Response in Chinese Patients With Typica

Dongke Wang,Chaofan Duan,Xiaohao Zhang,Junying Xu,Xiaohua Hou,Xuelian Xiang 대한소화기 기능성질환∙운동학회 2022 Journal of Neurogastroenterology and Motility (JNM Vol.28 No.4

Background/Aims Lyon consensus differentiates acid exposure time (AET) as physiological, borderline, and pathological. Mean nocturnal baseline impedance (MNBI) and post-reflux swallow-induced peristaltic wave index (PSPWi) are believed to increase diagnostic yield of gastroesophageal reflux disease (GERD) and correlate with symptom outcome of proton pump inhibitor (PPI) treatment. We aim to explore the clinical characteristics and the correlation of pH-impedance parameters with PPI response in Chinese patients with different AET levels. Methods We retrospectively investigated 177 patients with typical reflux symptoms who received esophageal function tests. The demographics, GERD questionnaire scores, the proportion of esophagitis and PPI responders, and manometric and pH-impedance parameters were compared among patients with AET < 4%, 4-6%, and > 6%. In patients with AET ≥ 4%, manometric and pH-impedance parameters were compared between PPI responders and non-responders. Results Among 177 patients, 69 (39.0%) had AET 4-6%, and 53 (29.9%) had AET > 6%. The demographics, esophagogastric junction type, and occurrence of ineffective esophageal motility were similar between patients with AET 4-6% and > 6%, but different from AET < 4%. MNBI and PSPWi were different among different AET levels, but similar between PPI responders and non-responders in patients with AET ≥ 4%. Conclusions It is reasonable to set 4% as a threshold to define pathological AET in Chinese patients. MNBI and PSPWi could identify GERD patients, but may not correlate with PPI response of Chinese GERD patients.

Biosynthesis of Isoprenoids: Characterization of a Functionally Active Recombinant 2-C-methyl-D-erythritol 4-phosphate Cytidyltransferase (IspD) from Mycobacterium tuberculosis H37Rv

Shi, Wenjun,Feng, Jianfang,Zhang, Min,Lai, Xuhui,Xu, Shengfeng,Zhang, Xuelian,Wang, Honghai Korean Society for Biochemistry and Molecular Biol 2007 Journal of biochemistry and molecular biology Vol.40 No.6

Tuberculosis, caused by Mycobacterium tuberculosis, continues to be one of the leading infectious diseases to humans. It is urgent to discover novel drug targets for the development of antitubercular agents. The 2-C-methyl-Derythritol-4-phosphate (MEP) pathway for isoprenoid biosynthesis has been considered as an attractive target for the discovery of novel antibiotics for its essentiality in bacteria and absence in mammals. MEP cytidyltransferase (IspD), the third-step enzyme of the pathway, catalyzes MEP and CTP to form 4-diphosphocytidyl-2-C-methylerythritol (CDP-ME) and PPi. In the work, ispD gene from M. tuberculosis H37Rv (MtIspD) was cloned and expressed. With N-terminal fusion of a histidine-tagged sequence, MtIspD could be purified to homogeneity by one-step nickel affinity chromatography. MtIspD exists as a homodimer with an apparent molecular mass of 52 kDa. Enzyme property analysis revealed that MtIspD has high specificity for pyrimidine bases and narrow divalent cation requirements, with maximal activity found in the presence of CTP and $Mg^{2+}$. The turnover number of MtIspD is $3.4 s^{-1}$. The Km for MEP and CTP are 43 and $92{\mu}M$, respectively. Furthermore, MtIspD shows thermal instable above $50^{\circ}C$. Circular dichroism spectra revealed that the alteration of tertiary conformation is closely related with sharp loss of enzyme activity at higher temperature. This study is expected to help better understand the features of IspD and provide useful information for the development of novel antibiotics to treat M. tuberculosis.