Objective:To investigate the corrosion fatigue strength of laser-welded specimens fabricated from commercially pure titanium (TA2) and titanium alloy(TC4). Methods:TA2 and TC4 were mechanically processed into a certain size and joined by laser welding. A fatigue testing machine was used to test tensile load and fatigue strength after soaked in synthetic saliva. The fatigue fracture surface was examined by scanning electron microscopy (SEM). Results: The fatigue strengths of the laser-welded test specimens showed no significant differences compared to specimens in air. SEM examination showed that there were no defects such as corrosion pits. Conclusion: There are no significant differences between either laser-welded metal in the corrosion fatigue strength for dry specimens and specimens in synthetic saliva.

Objective:Heme chloride(Hemin)is an in vitro purified form of natural heme and an important raw material for anti-anemia and antitumor drugs.This study aims to analyze the protective effect of Hemin on tissue damage in low-pressure oxygen chamber simulated plateau hypoxic mice,and explore its role in anti-plateau hypoxia. Methods:Thirty male BALB/c mice were randomly divided into a blank group,a positive drug group(acetazolomide,200 mg/kg),a Hemin low-dose group(15 mg/kg),a Hemin medium-dose group(30 mg/kg),and a Hemin high-dose group(60 mg/kg)with intraperitoneal injection.The anti-hypoxic activity of Hemin was explored by atmospheric closed hypoxia experiment and the optimal dose was screened.Thirty-six male BALB/c mice were randomly divided into a blank group,a hypoxia group,a positive drug group,and a Hemin high-dose group.The plasma inflammatory factor levels and oxidative stress indicators malondialdehyde(MDA),glutataione(GSH),and superoxide dismutase(SOD)levels of myocardium,brain,lung,and liver tissues were measured in different groups with hypoxia for 24 h.The degree of histopathological damage of mice was observed with HE staining.The degree of protection of Hemin against tissue hypoxia injury was detected with the hypoxia probe piperidazole. Results:Compared with the blank group,the survival time of mice in the positive drug group,the Hemin medium-dose group,and high-dose group was significantly extended(all P<0.05),with the highest prolongation rate in the Hemin high-dose group.Compared with the hypoxia group,mice in the Hemin high-dose group showed a significant increase in SOD level and GSH content of brain tissue,and a significant decrease in MDA content of lung tissue(all P<0.05).The results of HE staining and hypoxia probe showed that Hemin had a significant protective effect on the damage of liver,heart,brain and lung tissues of mice with hypoxia,and the most obvious effect on that of the brain tissue. Conclusion:Hemin has an effect of improvement on oxidative stress and inflammatory response caused by hypoxia,and has obvious protective effect on tissue damage caused by hypoxia.

Red blood cells(RBCs)are the primary mediators of oxygen transport in the human body,and their function is mainly achieved through conformational changes of hemoglobin(Hb).Hb is a tetramer composed of four subunits,with HbA being the predominant Hb in healthy adults,existing in two forms:tense state(T state)and relaxed state(R state).Endogenous regulators of Hb conformation include 2,3-diphosphoglyceric acid,carbon dioxide,protons,and chloride ions,while exogenous regulators include inositol hexaphosphate,inositol tripyrophosphate,benzabate,urea derivative L35,and vanillin,each with different mechanisms of action.The application of Hb conformational regulators provides new insights into the study of hypoxia oxygen supply issues and the treatment of sickle cell disease.

Areca catechu L. medicinal materials and their preparations are widely used in clinical practice. Betelnut polyphenol is one of the main chemical components with antioxidant, anti-inflammatory, and antibacterial effects. With continuous increase of high altitude activities, tissue oxidative damage caused by high altitude hypoxia seriously affects the ability to work, and the studies on anti-hypoxia drugs are particularly important. Recent studies have shown that betelnut polyphenols have protective effects on oxidative stress injury caused by hypoxia via improving blood gas index of hypoxic organism, increasing superoxide dismutase glutathione catalase activity, and scavenging excessive free radicals. The effects of betelnut polyphenols against hypoxia and oxidative damage protection suggest that betelnut polyphenols can be used as potential anti-hypoxia drugs and posses clinical prospects.
Antioxidants/pharmacology* ; Areca/chemistry* ; Humans ; Hypoxia ; Oxidative Stress ; Polyphenols/pharmacology* ; Superoxide Dismutase/metabolism*

Tibetan is a kind of medicine which extensively absorbed and fused the Chinese Traditional Medicine, Indian medicine and food through long-term practice and form the unique medical system. At the same time, the Qinghai Tibet plateau has characteristics of high altitude and lack of resources and oxygen, which has formed its unique geographical environment and grow a lot of rare medicinal plants. Tibetan medicine has a long history and is one of the relatively complete and influential ethnic medicines in China, which has played an important role in the treatment of plateau diseases. In recent years, with the increasing of economic activities in the plateau, the plateau anoxia had greatly affected the working capacity of the plateau. According to "Chinese medicine" through the literature, the pharmacological activities, active ingredients, growing environment of Tibetan medicine with good plateau hypoxia effect were reviewed and according to the site, which could be divided into the lung protection medicine, the cardiac protection medicine, the brain protection medicine, the liver protection medicine, the improvement of fatigue medicine and other medicine, which could provide theoretical basis for finding more potential anti-hypoxia drugs.