27 research outputs found
PO-154 Exercise induced redistribution of oxygen in internal organs
Objective Exercise induces tissue blood flow redistribution, which decreases splanchnic circulation and leads to physiologic hypoxia in the gastrointestinal (GI) system and liver. We hypothesized that the oxygen redistribution in the internal organs is affected by exercise.
Methods Twenty–four female 8-10wk ROSA26 ODD-Luc/+ mice (n= 6 per group) were used in this study. Three exercise models were conducted: (1) Moderate Exercise (ME): mice voluntarily swam for 30 min. (2) Heavy-intensity Exercise (HE): mice swam for 1.5 hours with 5% body weight loads attached to their tails. (3) Long-time Exercise (LE): mice voluntarily swam for 3 hours or till fatigue. Sedentary mice (SED) were used as controls. A hypoxic marker pimonidazole HCl was applied to detect tissue hypoxia. Pimonidazole HCl forms protein adducts when PO2 is under 10 mmHg. An hour after intraperitoneal injection of pimonidazole HCl (60 mg/kg body weight), the mice were anesthetized with isoflurane then sacrificed. The small intestine, colon, skeletal muscle, heart, liver, spleen and kidney specimens were fixed in 4% paraformaldehyde and stained with a specific monoclonal antibody against the pimonidazole HCl protein adducts to observe the hypoxic level of internal organs.
Results (1) The distributions of immunostaining intensity of pimonidazole HCl were different among the internal organs. In the kidney, the renal tubules demonstrated staining for hypoxia. In the liver, the positive staining was radiating outwards from central veins. In the small intestine and colon, there was the retention of pimonidazole HCl from the crypt to villus. (2) In the ME group, the extent of hypoxia in the kidney, liver and colon was increased compared with the SED. We found the small intestine is susceptible to exercise-induced tissue hypoxia distribution. Exercise resulted in a markedly increased staining in the crypts, whereas decreased staining in the villus. Intensified positive stains were observed in the nuclei of hypoxic cells, mostly in ME and HE groups. (3) The heart, skeletal muscle and spleen were not shown positive staining pre- and post-exercise.
Conclusions This study presented evidences that exercise induces the oxygen redistribution in the small intestine, colon, liver and kidney. The small intestine is susceptible to exercise induced physiological hypoxia
OR-026 Exercise induces HIF-1α redistribution in the small intestine
Objective Intestinal epithelial cells are positioned between an anaerobic lumen and a highly metabolic lamina propria, affected by reduced blood flow and tissue hypoxia. Exercise induces blood flow redistribution, leading to hypoperfusion and gastrointestinal (GI) compromise. The hypoxia-inducible factor (HIF) 1α is pivotal in the transcriptional response to oxygen flux. In this study, we hypothesized that exercise induces GI system hypoxia and accumulates HIF-1α.
Methods (1) ROSA26 ODD-Luc/+ mouse model (ODD-Luc) was used to detect HIF-1α expression in the intestine (female, 8-week, n=6/group). ODD-Luc mice were randomized into 4 groups: stayed in 21% O2 as the normoxic control (C), exercise (E), injected HIF-1α inhibitor PX-478 before swimming (PS), placed in the chamber containing 9% O2 for 4 hours as the positive control (PC). (2) Exercise models were conducted by volume: Moderate Exercise (ME): mice voluntarily swam for 30 min; Heavy-intensity Exercise (HE): mice swam for 1.5 hours with 5% body weight loads attached to their tails; Long-time Exercise (LE): mice voluntarily swam for 3 hours or till fatigue.
Results (1) Exercise increased HIF-1α in the abdominal area. The luciferase activities boosted after exercise, compared to the controls (ME v.s. C, P<0.05; HE v.s. C, P<0.05; LE v.s. C, P<0.05) but no differences among three exercise groups (ME v.s. HE, P>0.99; ME v.s. LE, P>0.99; HE v.s. LE, P>0.99); (2) Exercise altered HIF-1α distribution in the small intestine in a time-dependent manner. The expression of HIF-1α was significantly increased after exercise and gradually reduced to the rest level. The photons increased at the 0th hour after exercise compared to that of the normoxic control (P<0.01). The level of photons then reduced over time, while the 2nd, 4th and 6th hour post-exercise were still greater than that of the normoxic control (2nd hour v.s. C, P<0.01; 4th hour v.s. C, P<0.01; 6th hour v.s. C, P<0.05), and returned to normal after 24 hours (24th hour v.s. C, P>0.99).
Conclusions Exercise induced the distribution of HIF-1α in the small intestine. The expression of HIF-1α is shown in a time-dependent manner after exercise
Interface controlling and mechanisms of strengthening and toughening of graphene reinforced titanium matrix composites
The rapid development of aviation equipment such as hypersonic aircraft has put forward higher requirement for the comprehensive properties and application levels of titanium alloys. The properties of titanium alloys prepared by traditional thermal technologies have approached or reached the theoretical limit. Traditional technologies have been difficult to greatly improve the comprehensive properties of titanium alloys,and exploring graphene technology to modify titanium alloys has become an important development direction. However,it is difficult to control the interface reaction of graphene in titanium alloys. How to obtain the graphene/titanium interfaces with high bonding strength is the key to improve the performance of graphene reinforced titanium matrix composites. Based on the analysis of the problems restricting the development of graphene reinforced titanium matrix composites,this paper emphatically introduces the research progresses of microstructures,interface characteristics,static/dynamic mechanical properties,friction and wear properties,oxidation resistances,and strengthening and toughening mechanisms. The advantages and disadvantages of current solutions for dispersion uniformity,interface bonding and microstructure compactness are discussed. The challenges of interface control technology,large-scale preparation technology and performance stability of graphene reinforced titanium matrix composites are pointed out. Finally,it is proposed that such materials should be combined with theoretical calculation technologies, advanced preparation technologies and special function applications to deepen the interface optimization design and controllable preparation, and the application field expansion
Non-Isothermal Oxidation Behavior and Mechanism of a High Temperature Near-α Titanium Alloy
Non-isothermal oxidation is one of the important issues related to the safe application of high-temperature titanium alloys, so this study focuses on the non-isothermal oxidation behavior and mechanism of near-α titanium alloys. The thermogravimetry-differential scanning calorimetry (TGA/DSC) method was used to study the non-isothermal oxidation behavior of TA29 titanium alloy heated from room temperature to 1450 °C at a heating rate of 40 °C/min under pure oxygen atmosphere. The results show that non-isothermal oxidation behavior can be divided into five stages, including no oxidation, slow oxidation, accelerated oxidation, severe oxidation and deceleration oxidation; for the three-layer TiO2 scale, Zr, Nb, Ta are enriched in the intermediate layer, while Al is rich in the inner layer and Sn is segregated at the oxide-substrate interface, which is related to their diffusion rates in the subsurface α case. The oxidation mechanism for each stage is: oxygen barrier effect of a thin compact oxide film; oxygen dissolution; lattice transformation accelerating the dissolution and diffusion of oxygen; oxide formation; oxygen barrier effect of recrystallization and sintering microstructure in outer oxide scale. The alloying elements with high valence state and high diffusion rate in α-Ti are favorable to slow down the oxidation rate at the stage governed by oxide formation
Unified Treatment for Plasmon–Exciton Co-driven Reduction and Oxidation Reactions
Revealing the nature
of plasmon–exciton co-driven surface
catalytic reactions is important and urgent for developing potential
applications in energy and environmental science. In this work, we
propose a mechanism for plasmon–exciton co-driven surface catalytic
reactions based on our experimental results. We provide a method for
a unified treatment for reduction and oxidation reactions, which not
only strongly supports our proposed mechanism but also promotes a
deeper understanding of plasmon–exciton co-driven surface catalytic
reactions
Mechanistic Insight into Decomposition of 2<i>H</i>‑Azirines: Electronic Structure Calculations and Dynamics Simulations
In the present work, the combined
electronic structure calculations
and dynamics simulations have been performed to explore the decomposition
reactions of 2<i>H</i>-azirine, 2-phenyl-2<i>H</i>-azirine, and 3-phenyl-2<i>H</i>-azirine in gas phase.
Thermal cleavage of the C–C single bond yields nitrile ylides
as products with a high barrier (>50.0 kcal mol<sup>–1</sup>). On the other hand, photochemical cleavage reactions starting from
the <sup>1</sup>nπ* state of 2<i>H</i>-azirine and
3-phenyl-2<i>H</i>-azirine are ultrafast nonadiabatic processes
(<100 fs), leading to nitrile ylides through the S<sub>1</sub>/S<sub>0</sub> conical intersection. The fast formation of ylides in experiments
was well reproduced by present dynamics simulations. For 3-phenyl-2<i>H</i>-azirine, population of the S<sub>1</sub>(<sup>1</sup>ππ*)
state is another decay pathway for the S<sub>2</sub>(<sup>1</sup>nπ*)
state. The C–N bond cleavage upon photoexcitation was usually
considered to take place in T<sub>1</sub> state. However, our calculations
reveal that photocleavage of the C–N single bond for 2-phenyl-2<i>H</i>-azirine is very likely to take place in S<sub>1</sub> state.
The present work provides new insights into photocleavage mechanism
of 2<i>H</i>-azirine and the related derivatives
Physical activity, screen viewing time, and overweight/obesity among Chinese children and adolescents: an update from the 2017 physical activity and fitness in China—the youth study
Abstract Background With increases in inactive lifestyles and mounting pressure for academic excellence in Chinese younger populations, lack of physical activity and increased prevalence of obesity have become a major public health concern in China. The purpose of this study is to provide updated estimates on the prevalence of meeting moderate-vigorous physical activity (MVPA) and screen viewing time guidelines, and overweight and obesity among Chinese school-aged children and adolescents, with a secondary aim examining variations in prevalence by sex, grade groupings, and residential location. Methods The study sample came from the 2017 Physical Activity and Fitness in China—The Youth Study, a cross-sectional and national survey of 131,859 students (aged 7 to 19 years) from 986 public schools in China. Measures of MVPA, screen viewing time, and age- and sex-specific overweight and obese body mass index were used to calculate national prevalence estimates of Chinese school-aged children and adolescents. Results In 2017, 34.1% (95% confidence interval [CI], 34.09–34.11%) of children and adolescents met MVPA guidelines and 65.4% (95% CI, 65.39–65.41%) adhered to screen viewing time guidelines. The prevalence of overweight and obesity was 15.1% (95% CI, 15.09–15.11%) and 10.7% (95% CI, 10.69–10.71%), respectively. Prevalence estimates differed by sex (boys, girls), grade grouping (primary schools, junior middle schools, junior high schools), and residential location (rural, urban). Conclusions There remains a low prevalence of meeting MVPA guidelines and high prevalence of overweight and obesity in Chinese school-aged children and adolescents. Future efforts should focus on monitoring the trend of these behavioral and health risk factors to inform school policies and programs aimed at increasing physical activity and reducing and preventing obesity in younger populations in China