Effect Of High Altitude Environment Research Articles

Effect of High Altitude Environment on Pharmacokinetic and Pharmacodynamic of Warfarin in Rats.

High altitude environment affects the pharmacokinetic (PK) parameters of drugs and the PK parameters are an important theoretical basis for guiding the rational clinical use of drugs. Warfarin is an oral anticoagulant of the coumarin class commonly used in clinical practice, but it has a narrow therapeutic window and wide individual variation. However, the effect of high altitude environment on PK and pharmacodynamic (PD) of warfarin is unclear. The objective of this study is to investigate the effect of a high altitude environment on PK and PD of warfarin in rats. Rats were randomly divided into plain group and high altitude group and blood samples were collected through the orbital venous plexus after administration of 2 mg/kg warfarin. Warfarin concentrations in plasma samples were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and PK parameters were calculated by the non-compartment model using WinNonlin 8.1 software. Meanwhile, the expression of PXR, P-gp and CYP2C9 in liver tissues was also determined by western blotting. The effect of high altitude environment on PD of warfarin was explored by measuring activated partial thromboplastin time (APTT) and prothrombin time (PT) values and then calculated international normalized ratio (INR) values based on PT. Significant changes in PK behaviors and PD of warfarin in high altitude-rats were observed. Compared with the plain-rats, the peak concentration (Cmax) and the area under the plasma concentration-time curve (AUC) increased significantly by 50.9% and 107.46%, respectively. At the same time, high altitude environment significantly inhibited the expression of PXR, P-gp and CYP2C9 in liver tissues. The results of the PD study showed that high altitude environments significantly prolonged PT, APTT and INR values. High altitude environment inhibited the metabolism and increased the absorption of warfarin in rats and increased the effect of anticoagulant effect, suggesting that the optimal dose of warfarin for patients at high altitude should be reassessed.

The effect of high altitude environment on diesel engine performance: Comparison of engine operations in Hangzhou, Kunming and Lhasa cities

The all-area operating performance of the vehicles requires the development of diesel engines that can operate at high altitudes without significant performance deterioration. Prior to optimizing the efficiency and emissions of highland engines, there is a necessity to investigate the underlying causes of engine performance degradation. The purpose of this paper was to study the in-cylinder activities occurring in the combustion chamber of diesel engines at high altitudes, which can help explain the effect of altitude on engine efficiency and emissions of concern to the customer. Specifically, a turbocharged direct injection compression ignition engine was operated at a constant engine speed and load, but at different altitudes. The theoretical analyses based on experimental data suggested that the mismatch between air and diesel quantities caused by the high altitude atmosphere led to the engine combustion deterioration. Specifically, the lower gas density at high altitudes during fuel injection resulted in a reduction of the injection angle and an enhancement of the penetration capability. In addition, the rise in altitude extended the ignition delay, which increased the fuel fraction mixed with air in the premixed combustion stage and raised the pressure rise rate. Moreover, at high altitudes, the reduction in excess air ratio and increased possibility of wall impingement of the fuel droplets resulted in uneven mixture concentration distribution and reduced air utility. Accordingly, combustion deterioration occurred in the combustion chamber of the plateau engines, which reduced energy release during main mixing-controlled combustion, lowered combustion efficiency, increased exhaust energy, and raised engine-out incomplete combustion emissions. All these effects resulted in a decrease in engine thermal efficiency of ∼6.5% and an increase in soot emissions of ∼4.2 times from Hangzhou to Lhasa city for the engine and operating conditions investigated in this study. Consequently, engines operating in highland areas need to be optimized in terms of efficiency and emissions.

Sleep quality among elderly high-altitude dwellers in Ladakh

It has been already known that people who temporarily stay at high altitude may develop insomnia as a symptom of acute mountain sickness. However, much less is known about people living at high altitude. The aim of this study was to determine the effect of high altitude environment on sleep quality for the elderly who have been living at high altitude for their whole lives. A cross-sectional study was conducted in Domkhar valley at altitudes of 2800–4200m, Ladakh. Sleep quality was assessed using Insomnia Severity Index (ISI). Measurement items include body mass index, blood pressure, blood sugar, hemoglobin, timed Up and Go test, oxygen saturation during wakefulness, respiratory function test, Oxford Knee Score (OKS), and Geriatric Depression Scale (GDS), and so on. The participants were Ladakhi older adults aged 60 years or over (n=112) in Domkhar valley. The participation rate was 65.1% (male: female=47:65, mean age: 71.3 years and 67.9 years, respectively). The prevalence of the high score of ISI (8 or more) was 15.2% (17 out of 112). Altitude of residence was significantly correlated with ISI. Stepwise multiple regression analysis showed that OKS and altitude of residence were significantly related with ISI.

Effects of high altitude and nutritional status over the physical fitness of young Nepalese residing in Pokhara, Kaski district of western Nepal

Pokhara is situated over 5,577ft above sea level in The Kingdom of Nepal. Such high-hilly regions of Nepal contain only one-third as much oxygen as sea level air and in order to acclimatize to such environmental hypoxia, a series of metabolic and musculocardio-respiratory adaptations initiate that influence oxygen transport and utilization, which is necessary to achieve optimal physical performance at altitude. The health of people residing at such high altitude is determined not only by the environment but also by means of nutritional determinants. The present study was conducted to explicate the effect of high altitude environment with nutritional factors over physical fitness of young Nepalese of Pokhara. Twenty-five male young Nepalese were randomly selected from Pokhara, Nepal (mean age 21.6) and twenty-five sedentary college students of Kolkata, India (mean age 21.9) were taken as controls. Results showed a significant difference in BMI, body fat percentage, pre- and post-exercise BP, PFI, VO2max, energy expenditure and anaerobic power (P<0.05). Young adults of Nepal are also found to be deficient in protein, calcium and iron in their diet, describing their poor nutritional status. Together these data entail that the physical fitness of young adults of Nepal is under the influence of environmental factors as well as their nutritional status.South East Asia J Public Health | Jan-June 2012 | Vol 2 Issue 1 | 34-38 DOI: http://dx.doi.org/10.3329/seajph.v2i1.15263

Decaploidy inRosa praelucensByhouwer (Rosaceae) Endemic to Zhongdian Plateau, Yunnan, China

Abstract Genus Rosa (Rosaceae) has a base chromosome number of x = 7. Ploidy levels of wild species range from 2n= 2x= 14 to 2n= 8x=56. In this paper, one decaploid, the highest naturally occurring ploidy never reported before in the genus was detected in the karyological study of an endemic wild species, R. praelucens Byhouwer to Zhongdian Plateau, Yunnan, China. Its karyotype formula was 2n=10x=70=2st+6sm+62m and the karyotype was 2B. Chromosome No. 6 was subterminal. Chromosome No. 15, No. 22 and No. 23 were submedian. According to its karyomorphology, R. praelucens derived not from auto polyploidization directly but from inter-specific hybridization. Polyploidization and inter-species hybridization both might have played important roles in the origin of R. praelucens associated with effect of high altitude environment. Further research on this species is warranted to provide helpful evidences to understand the differentiation and evolution of the Genus Rosa, and even clues to trace the process of spec...

Effects of High-Altitude Environment on the Cardiovascular System of Man

Cardiac output during exercise is decreased after a prolonged sojourn at high altitude. The maximal oxygen uptake at high altitude, which persists at a low value even after arterial oxygen content normalizes, is reduced because of these changes in cardiac output. Alterations of both heart rate and stroke volume contribute to this decrease. The etiologies of these changes are not known, but failure to restitute stroke work to sea-level values with dextran 75 infusion suggests altered myocardial function. The superior physical performance of high-altitude natives may be due to cardiovascular adaptation to hypoxia.

Effects of high-altitude environment on the cardiovascular system of man

Effects of high-altitude environment on the cardiovascular system of man