Search

Aim: The aim of this study was to explore the prediction factors for incidence of acute mountain sickness (AMS) in young males newly entering highland areas., Methods: A retrospective study of 4367 records of male highland soldiers from 2000 to 2005 was done. The factors were tested by logistic regression., Results: After selection by univariate model, ethnicity, altitude, season, deployment type, and prophylaxis were inserted into a multivariate model. The adjusted odds ratio (AOR) was 0.078 for Tibetan compared with Han. AORs for altitudes 3600 to 3700, 4000 to 4300, and 4600 to 4700 m versus 2900 to 3100 m were 4.490, 4.532, and 4.964, respectively. AOR for cold season versus warm season was 1.332. AORs for emergency land deployment and air deployment versus normal land deployment were 2.261 and 1.614, respectively. The AOR was 0.741 for prophylaxis versus none. The area under receiver operating characteristic curve was 0.731 (optimal cutoff = 0.370)., Conclusions: Adjusting for altitude, risk factors that contributed to AMS were being non-Tibetan, cold season, greater speed of transport, emergency conditions, and without prophylaxis. The model established is acceptable for assisting AMS prediction., (© 2011 APJPH.)

High-altitude pulmonary edema (HAPE) is a non-cardiogenic pulmonary edema that is always found among unacclimatized persons after rapid ascent to high altitude, and HAPE is caused by the interaction of genetic and environmental factors. To screen and analyze the susceptibility genes and single nucleotide polymorphisms (SNPs) of HAPE in Han Chinese, the DNA samples of 40 patients with HAPE and 33 healthy controls, who performed the reconstruction tasks from the plain region in Yushu area of Qinghai province during May of 2010 to July of 2012, were scanned by Affymetrix SNP Array 6.0 Chips in this study. Genome-wide association study (GWAS, by PLINK software) was used to screen the susceptibility genes and genetic markers, and a total of 57 SNPs were found to be significantly different between case and control groups (adjust P < 0.05). GO and Pathway enrichment analysis of 74 genes around the 57 SNPs indicated that these genes were significantly correlated with prostanoid metabolic process, arachidonic acid metabolism and nitrogen metabolism (adjust P < 0.05), which were involved in the physiopathologic mechanism of HAPE. Our studies suggest that these genetic polymorphisms and genes were associated with HAPE.

High altitude sickness (HAS) occurs among humans visiting or inhabiting high altitude environments. Genetic differences in the EPAS1 and EGLN1 genes have been found between lowland (Han) and highland (Tibetan) Chinese. Three SNPs within EPAS1 and EGLN1 were evaluated in Han and Tibetan patients with acute mountain sickness (AMS) and chronic mountain sickness (CMS). We compared 85 patients with AMS to 79 Han unaffected with mountain sickness (MS) as well as 45 CMS patients to 34 unaffected Tibetan subjects. The three SNPs studied were EPAS1 [ch2: 46441523 (hg18], EGLN1 (rs480902) and (rs516651). Direct sequencing was used to identify individual genotypes for the three SNPs. Age was found to be significantly associated with the EPAS1 SNP in the CMS patients while heart rate (HR) and oxygen saturation level of hemoglobin (SaO(2)) were found to be significantly associated with the EGLN1 (rs480902) SNP in the Han patients with AMS. The individuals with CMS were found to diverge significantly for the EPAS1 SNP compared to their Tibetan control group as measured by genetic distance (0.123) indicating positive selection of the EPAS-G allele with age and illness. The EGLN1 (rs480902) SNP had a significant correlation with hematocrit (HCT), HR and SaO(2) in AMS patients. AMS and CMS were found to be significantly associated with the EPAS1 and EGLN1 SNPs compared to their Han and Tibetan control groups, respectively, indicating these nucleotide alterations have a physiological effect for the development of high altitude sickness., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Background: The role of genetics in determining an individual's susceptibility to high altitude pulmonary edema (HAPE) is unclear. However a number of genetic polymorphisms have recently been found to be overrepresented in patients with HAPE. Changes at the mitochondrial level may play an important role in the human body's adaptation to hypoxia. Polymorphisms of mitochondrial DNA (mtDNA) have been shown to be responsible for differences in organelle function. Therefore, the frequency of mtDNA 3397A/G and 3552T/A polymorphisms were studied to determine their potential role in HAPE., Objectives: To further study the role of mtDNA 3397A/G and 3552T/A variations of reduced nicotinamide adenosine dinucleotide dehydrogenase 1 in HAPE susceptibility., Methods: The single-nucleotide polymorphisms of mtDNA 3397 and 3552 in patients with HAPE (n = 132) and their matched control subjects (n = 233) were studied using polymerase chain reaction sequencing., Results: The frequency of mtDNA 3397G in the HAPE group (2.3%) was significantly higher than that of the control group (0%; P = .021; odds ratio, 2.806; 95% confidence interval, 2.443 to 3.223). The frequency of mtDNA 3552A in the HAPE group (6.8%) also was significantly higher than in the control group (1.7%; P = .012; odds ratio, 4.198; 95% confidence interval, 1.264 to 13.880)., Conclusions: In this study, we present the first evidence of differences in mtDNA polymorphism frequencies between HAPE victims and healthy Han Chinese. Genotypes of mtDNA 3397G and 3552A were correlated with HAPE susceptibility. This result could contribute to defining the role of the mitochondrial genome in the pathogenesis of HAPE., (Copyright © 2012. Published by Elsevier Inc.)

Purpose: To estimate the prevalence of dry eye disease, analyze the associations between dry eye symptoms and signs, and identify the risk factors in an elderly Mongolian population at high altitude in China., Methods: A population-based survey was conducted in 2006. A total of 2,486 Mongolians age 40 and older were selected. Symptoms of dry eye were assessed using a 6-item validated questionnaire. Dry eye disease was defined if participants reported one or more symptoms often or all the time. Positive signs included a tear-film breakup time of or= 1 in one or both eyes. Presence of dry eye symptoms and positive signs were analyzed. Correlations between symptoms and signs, and risk factors were evaluated in a multivariate model., Results: Of the 1,816 participants, 50.1% (95% confidence interval, 47.8-52.4) were symptomatic. Tear-film breakup time of or= 1 was 6.0% (95% confidence interval, 4.9-7.1). The correlation between dry eye symptoms and positive signs (tear-film breakup time of or=1 [r = 0.361, P < 0.001]) were statistically significant. Independent risk factors included increased age, age-related cataract and pterygium., Conclusion: This study demonstrates a high prevalence rate of dry eye disease in a Mongolian population. Dry eye signs were significantly associated with dry eye symptoms.

Since the beginning of the Himalayan climbing era, the anecdotal extraordinary physical performance at high altitude of Sherpas and Tibetans has intrigued scientists interested in altitude adaptation. These ethnic groups may have been living at high altitude for longer than any other population, and the hypothesis of a possible evolutionary genetic adaptation to altitude makes sense. Reviewed here is the evidence as to whether Tibetans are indeed better adapted for life and work at high altitude as compared to other populations and, if so, whether this better adaptation might be inborn. Tibetans, compared to lowlanders, maintain higher arterial oxygen saturation at rest and during exercise and show less loss of aerobic performance with increasing altitude. Tibetans have greater hypoxic and hypercapnic ventilatory responsiveness, larger lungs, better lung function, and greater lung diffusing capacity than lowlanders. Blood hemoglobin concentration is lower in Tibetans than in lowlanders or Andeans living at similar altitudes. Tibetans develop only minimal hypoxic pulmonary hypertension and have higher levels of exhaled nitric oxide than lowlanders or Andeans. Tibetans' sleep quality at altitude is better and they desaturate less at night. Several of these findings are also found in Tibetans born at low altitude when exposed for the first time to high altitude once adult. In conclusion, Tibetans indeed seem better adapted to life and work at high altitude, and this superior adaptation may very well be inborn, even though its exact genetic basis remains to be elucidated.