Objective To investigate optimal method of establishing hypoxia/reoxygenation(H/R) model of H9c2 cell by using hypoxia/anoxic workstation under different conditions in hypoxia.Methods H9c2 cell was placed into hypoxia/anoxic workstation and simultaneously cultured with complete medium, glucose-free DMEM and acidic hypoxic solution for 1,2,4,6 and 8 h respectively, and then reoxygenated with complete medium for 1 h in normoxic incubator.The level of ROS was measured by flow cytometry.The cell viability was detected by MTT assay.The cellular morphology was observed by inverted microscope.Results With the extension of cell hypoxia time, there were no significant differences in the ROS level and cell viability in complete medium-and glucose-free DMEM-treated H/R groups compared with control group(P<0.05).There was no obvious morphologic change observed with inverted microscope, either.Nevertheless, when H9c2 cells were treated with acidic hypoxic solution in hypoxia, the ROS level continuously increased and the cell viability decreased with the extension of cell hypoxia time ( P<0.01 ).Since H:1 h/R:1 h, some of the cells shrunk and a few necrotic cells floated in the media under the inverted microscope , and the damage was aggravated with the extension of hypoxia time.After the cells were exposed in hypoxia for 8 h, they wrinkled to be round and a large number of floating necrotic cells were observed.When the cells were reoxygenated for 1 h, the cytomembrane was not smooth and there were still a few necrotic cells floating in culture dish .Conclusion The H9c2 cell H/R model with good repeatability can be established successfully by using hypoxia/anoxic workstation combining with acidic hypoxic solution.

Wechat has been widely used in nursing clinical clerkship teaching now. The application of Wechat in nursing clinical teaching mainly takes the form of Wechat group chat, Wechat public signal platform, Wechat friendship circle, online test and so on. Among them, Wechat group chat and Wechat public signal platform are used widely. Wechat enriches the teaching way, and improve the effectiveness of teaching, moreover, it facilitates the relationship between teachers and students. However, there are the ongoing challenges such as lacking of supervision and protection of intellectual property rights.

Postprandial hypotension is an abnormal regulation of blood pressure, which is common in the elderly. Due to insidious symptoms, postprandial hypotension is easily neglected by patients and medical staff in clinical practice, but it has a high degree of harm. There are many factors related to the occurrence of postprandial hypotension, including demographic factors, disease-related factors, lifestyle factors, postprandial postural factors and so on. Among demographic factors, age is positively associated with the occurrence of postprandial hypotension. Among disease-related factors, the existence of some basic diseases such as hypertension and diabetes, and the use of most kinds of anti-hypertensive drugs can increase the risk of postprandial hypotension. Among lifestyle factors, smoking is a risk factor for postprandial hypotension: while reducing the intake of staple foods, drinking large amounts of water or drinking green tea before meals may reduce the risk of postprandial hypotension. By taking different postures after meals, postural factors affect the rate of gastrointestinal emptying and then affect the occurrence of postprandial hypotension. Among the above factors, it is feasible to prevent postprandial hypotension by changing postprandial posture.

Objective: To show development status of postprandial hypotension studies comprehensively and intuitively in order to provide a reference for nursing research on postprandial hypotension. Methods: The data was from the literatures included in Web of Science database from 1986 to 2019 related to postprandial hypotension, and CiteSpace information visualization software was used to analyze the issuing country and institution, cited authors, Cited journals, keywords and cited references to postprandial hypotension. Results: A total of 1 140 literatures were obtained. 187 papers were finally included after screening. University of Adelaide in Australia has the most of published articles and the most of cited authors; The cited journals mainly include international high-impact journals such as Annals of Internal Medicine and Journal of the American Geriatrics Society. Through keywords clustering, a total of 5 research hotspots were obtained, including falls, insulin, autonomic nervous system, aged cared, gastrointestinal. Conclusions Postprandial hypotension is one of the convergence points of interdisciplinary fusion. At present, preliminary results have been obtained, but the research on its mechanism is still in the exploratory stage. Falls, insulin, autonomic nervous system, aged cared, gastrointestinal are currently the main focus of postprandial hypotension researches. The prevention of postprandial hypotension has made some achievements, but there are also some risks. It is necessary to conduct further studies on more convenient and safe measures to prevent postprandial hypotension.