GCH1 plays a role in the high-altitude adaptation of Tibetans

Tibetans are welt adapted to high-altitude hypoxia. Previous genome-wide scans have reported many candidate genes for this adaptation, but only a few have been studied. Here we report on a hypoxia gene （GCH1, GTP-cyclohydrolase I）, involved in maintaining nitric oxide synthetase （NOS） function and normal blood pressure, that harbors many potentially adaptive variants in Tibetans. We resequenced an 80.8 kb fragment covering the entire gene region of GCH1 in 50 unrelated Tibetans Combined with previously published data, we demonstrated many GCHI variants showing deep divergence between highlander Tibetans and lowlander Han Chinese. Neutrality tests confirmed a signal of positive Darwinian selection on GCH1 in Tibetans. Moreover, association analysis indicated that the Tibetan version of GCH1 was significantly associated with multiple physiological traits in Tibetans, including blood nitric oxide concentration, blood oxygen saturation and hemoglobin concentration. Taken together, we propose that GCH1 plays a role in the genetic adaptation of Tibetans to high altitude hypoxia.

Studies on monitoring hemodynamics and oxygen dynamics of adult respiratory distress syndrome secondary to high altitude pulmonary edema

To study monitoring hemodynamics and oxygen dynamics of adult respiratory distress syndrome (ARDS) secondary to high altitude pulmonary edema (HAPE),we performed clinic and laboratory studies in 8 patients who preliminarily developed high altitude cerebral edema (HACE) and then ARDS occurred at an altitude of 4 500 m. After an initial emergency treatment on high mountains,all the patients were rapidly transported to a hospital at a lower altitude of 2 808 m. The right cardiac catheterizations were carried out within 5 h after hospitalized. The monitoring hemodynamics and oxygen dynamics were studied via a thermodilution Swan-Gaze catheter. The results showed that before treatments at the beginning of monitoring,there presented a significant pulmonary artery hypertension with a decreased cardiac function,and a lower oxygen metabolism in all the 8 patients. However,after some effective treatments,including mechanical ventilation and using dexamethasone,furosemide,etc,four days later the result of a repeated monitoring showed that their pulmonary artery pressure had been decreased with an improved cardiac function with all the oxygen metabolic indexes increased significantly. Our studies suggested that performing monitoring hemodynamics in patients with ARDS secondary to HAPE will define the clinical therapeutic measures which will benefit the outcome.

EP300 contributes to high-altitude adaptation in Tibetans by regulating nitric oxide production

The genetic adaptation of Tibetans to high altitude hypoxia likely involves a group of genes in the hypoxic pathway, as suggested by earlier studies. To test the adaptive role of the previously reported candidate gene EP300 （histone acetyltransferase p300）, we conducted resequencing of a 108.9 kb gene region of EP300 in 80 unrelated Tibetans. The allele-frequency and haplotype-based neutrality tests detected signals of positive Darwinian selection on EP300 in Tibetans, with a group of variants showing allelic divergence between Tibetans and lowland reference populations, including Han Chinese, Europeans, and Africans. Functional prediction suggested the involvement of multiple EP300 variants in gene expression regulation. More importantly, genetic association tests in 226 Tibetans indicated significant correlation of the adaptive EP300 variants with blood nitric oxide （NO） concentration. Collectively, we propose that EP300 harbors adaptive variants in Tibetans, which might contribute to high-altitude adaptation through regulating NO production.

Ataxia,acute mountain sickness,and high altitude cerebral edema

Previous investigations suggest that ataxia is common and often one of the most reliable warning signs of high altitude cerebral edema(HACE). The aim of this study was to investigate the diagnostic role of ataxia in acute mountain sickness(AMS)and HACE among mountain rescuers on the quake areas,and in approaching the relation between AMS and HACE. After the earthquake on April 14,2010,approximately 24 080 lowland rescuers were rapidly transported from sea level or lowlands to the mountainous rescue sites at 3 750 ~ 4 568 m,and extremely hardly worked for an emergency treatment after arrival. Assessments of acute altitude illness on the quake areas were using the Lake Louise Scoring System. 73 % of the rescuers were found to be developed AMS. The incidence of high altitude pulmonary edema(HAPE)and HACE was 0.73 % and 0.26 %,respectively,on the second to third day at altitude. Ataxia sign was measured by simple tests of coordination including a modified Romberg test. The clinical features of 62 patients with HACE were analyzed. It was found that the most frequent,serious neurological symptoms and signs were altered mental status(50/62,80.6 %)and truncal ataxia(47/62,75.8 %). Mental status change was rated slightly higher than ataxia,but ataxia occurred earlier than mental status change and other symptoms. The earliest sign of ataxia was a vague unsteadiness of gait,which may be present alone in association with or without AMS. Advanced ataxia was correlated with the AMS scores,but mild ataxia did not correlate with AMS scores at altitudes of 3 750~4 568 m. Of them,14 patients were further examined by computerized tomographic scanning of the brain and cerebral magnetic resonance imagines were examined in another 15 cases. These imaging studies indicated that the presence of the cerebral edema was in 97 % of cases who were clinically diagnosed as HACE(28/29). Ataxia seems to be a reliable sign of advanced AMS or HACE,so does altered mental status.

Subclinical high altitude pulmonary edema: A clinical observation of 12 cases in Yushu

During the Yushu Earthquake on April 14,2010,a high incidence of acute high altitude illness was observed in the mountain rescuers,and 0.73 % of these patients suffered from high altitude pulmonary edema,of which 12 patients developed subclinical pulmonary edema and concomitantly contracted acute mountain sickness. Symptoms and signs were atypically high heart rate with high respiratory rate,striking cyanosis,and significantly low oxygen saturation,whereas no moist rates were heard on auscultation,and Chest X-ray showed peripheral with a patchy distribution of mottled infiltrations in one or both lung fields. We believe that subclinical high altitude pulmonary edema is an earliest stage of pulmonary edema at high altitude. The possible pathogenesis and the diagnosis were discussed.

Sleep quality alterations in healthy workers at high altitude in Yushu area

During the period of reconstruction after Yushu Earthquake,a large number of sea-level or low land workers ascended there and worked at altitudes between 3 750 m and 4 878 m which is a hypoxic environment. To investigate the sleep quality at that altitude,we performed two full polysomnographies (PSGs) in 10 volunteers,who were healthy male workers,aged 31±6.6,born and living at sea level,without experience of pre-altitude exposure. The assessment of subjective sleep quality was performed twice in each volunteer. The first investigations were carried out at sea level in Jinan city (p B =760 torr,1 torr=133.322 4 Pa). The second studies were performed at an altitude of 3 750 m (p B =416 torr) in Yushu Jiegu in the same 10 workers after they lived and worked at that altitude for 5 months. At sea level,workers presented a normal sleep structure and a higher oxygenation during sleep. However,as compared to sea-level sleep,at 3 750 m,workers had a shorter total sleep time (TST) (p<0.001),a longer stage 1 non-rapid eye movement (nREM) sleep (p<0.05) and a shorter 3+4 nREM and rapid eye movement (REM) sleep (p<0.05) with a severe sleep hypoxemia (p<0.01). Our data suggested that sea-level workers revealed a disturbed sleep and a bad sleep quality with a significant sleep hypoxemia at altitude of 3 750 m. Strengthening the prevention and treatment are thereby sorely necessary.

Rong Shuan Jiao Nang in the treatment of acute mountain sickness and high altitude myocardial ischemic syndrome in Yushu

To evaluate the therapeutic effects of Rong Shuan Jiao Nang (RSJN) on treatment of acute mountain sickness (AMS) and high altitude myocardial ischemic syndrome in workers in Yushu,three groups were studied: group A (60 patients with AMS,given RSJN),group B (15 patients with altitude myocardial ischemic syndrome, given RSJN),and group C (control,without drugs). All studied subjects were lowland workers who were first time entry to Yushu for work at an altitude of 4 250 m. During the course of treatment,a routing physical examination was performed,AMS Lake Louise Scores were estimated,arterial oxygen saturation (SaO2),electrocardiography and hemoglobin concentration were measured before and after using RSJN for 10 days. In group A,the effective rate was 68 %,symptomatic improvement in 54 cases (90 %) within 5 days. In group B,the effective rate was 93 %,episodes of angina pectoris stopped in 12 patients within 3 ~ 7 days,one lasted 8 days. After treatment, the level of SaO2 increased 15.5 %,21.8 % and 5.6 % in group A,group B and group C,respectively. RSJN taken at the start of the arrival at Yushu can decrease AMS scores and facilitate cure. If taken after the illness has begun,RSJN may help lessen symptoms,especially effectively improved angina pectoris of the high altitude myocardial ischemic syndrome. Symptoms usually subside after 3 ~ 8 days. RSJN should be continually used for at least 7 days after ascent.

High altitude headache occurs frequently among construction workers in Yushu

The aim was to measure the incidence of high altitude headache(HAH)and to determine clinical features,as well as the relation between acute mountain sickness(AMS)and HAH through a prospective study. We conducted a questionnaire-based study among construction workers in Yushu after a serious earthquake;they were under reconstruction using a structured questionnaire incorporating International Headache Society(IHS) and AMS Lake Louise Scoring System. A total of 608 workers were enrolled after their first ascent to altitudes of 3 750~4 528 m. The results showed that 96 % reported at least 1 HAH(median 3.8,range from 1 to 10)in workers at a mean altitude of 4 250 m. The magnitude of headache was divided as mild(38 %),moderate(44 %)and severe(18 %). This study indicates that HAH is the most common symptom of acute altitude exposure and closely correlated with altitude(r=0.165,p<0.001). However,52 % of headache was one of the main symptoms of AMS, while the other 48 % was the sole symptom of HAH. On the contrary we found that 2 % of AMS without headache,thus the'painless AMS'actually existed. The clinical features of HAH are presented,and the relationship between AMS and HAH is discussed.

Association of HER2 status with prognosis in gastric cancer patients undergoing R0 resection: A large-scale multicenter study in China

AIM: To determine whether the positive status of human epidermal growth receptor 2(HER2) can be regarded as an effective prognostic factor for patients with gastric cancer(GC) undergoing R0 resection.METHODS: A total of 1562 GC patients treated by R0 resection were recruited. HER2 status was evaluated in surgically resected samples of all the patients using immunohistochemical(IHC) staining. Correlations between HER2 status and clinicopathological characteristics were retrospective analyzed. Hazard ratios(HRs) and 95% confidence intervals(CIs) were estimated using Cox proportional hazard model, stratified by age, gender, tumor location and tumor-nodemetastasis(TNM) stage, with additional adjustment for potential prognostic factors.RESULTS: Among 1562 patients, 548(positive rate = 35.08%, 95%CI: 32.72%-37.45%) were HER2 positive. Positive status of HER2 was significantly correlated with gender(P = 0.004), minority(P < 0.001), tumor location(P = 0.001), pathological grade(P < 0.001), TNM stage(P < 0.001) and adjuvant radiotherapy(74.67% vs 23.53%, P = 0.011). No significant associations were observed between HER2 status and disease free survival(HR = 0.19, 95%CI: 0.96-1.46, P = 0.105) or overall survival(HR = 1.19, 95%CI: 0.96-1.48, P = 0.118) using multivariate analysis, although stratified analyses showed marginally statistically significant associations both in disease free survival and overall survival, especially among patients aged < 60 years or with early TNM stages(Ⅰ and Ⅱ). Categorical age, TNM stage, neural invasion, and adjuvant chemotherapy were, as expected, independent prognostic factors for both disease free survival and overall survival. CONCLUSION: The positive status of HER2 based on IHC staining was not related to the survival in patients with GC among the Chinese population.

A genetic adaptive pattern-low hemoglobin concentration in the himalayan highlanders

Mean hemoglobin(Hb) concentration of about 3 500 subjects derived from 17 studies of Himalayan highlanders(Tibetans, Sherpas, and Ladakhis) was compared with lowlanders(Chinese Han, Indian Tamils) lived in the Himalayas, and European climbers during Everest expeditions as well as Andean natives. The results found that Hb concentration in Himalayan highlanders was systemically lower than those reported for Andean natives and lowland immigrants. These comparative data demonstrated that a healthy native population may successfully reside at high altitude without a significant elevation in Hb, and the lower Hb levels of Himalayan highlanders than those of migrated lowlanders and Andean natives are an example of favourable adaptation over the generations. In addition, excessive polycythemia has frequently been used as a marker of chronic mountain sickness(CMS). Altitude populations who have a higher Hb concentration also have a higher incidence of CMS. The low Hb in Himalayans suggested as showing adaptation over many generations in Tibetan stock. Recent work in Tibet, suggested that Tibetans there may have adapted to high altitude as a result of evolutionary pressure selecting for genes which give an advantage at altitude. All of the population genomic and statistical analysis indicated that EPAS1 and EGLN1 are mostly likely responsible for high altitude adaptation and closely related to low Hb concentration in Tibetans. These data supported the hypothesis that Himalayan highlanders have evolved a genetically different erythropoietic response to chronic hypoxia by virtue of their much longer exposure to high altitude.

Medical mountain rescue in the Yushu Earthquake: Have lessons been learned?

On April 14,2010,an earthquake reaching Richter scale 7.1 struck Jiegu Town of Yushu,a mountain rescue operation promptly launched. All injurers had a direct assess to take medical care,and were immediately rescued and rapidly evacuated by air to Xining and Golmud at lower altitudes and admitted to advanced hospitals. Almost all of the injurers have been completely recovered. Yushu Earthquake was one of the highest earthquakes in the world,with a high incidence of acute altitude illness,which was observed in about 80 % of the lowland rescuers at an altitude of 4 000 m."Rescue the rescuers"became the major task of Qinghai-Tibetan rescue teams,all the severe patients were rapidly descended to Xining and treated promptly and effectively. The outcome was excellent,all patients survived. After the earthquake,it is a long and arduous task to reconstruct what has been destroyed. Medical teams continue to work in the Yushu Earthquake area because about 30 000 workers and carders are now here for rebuilding the earthquake center. Thus the prevention and treatment of altitude illness are still critical tasks for medical teams. Although all the fights are successful,there are more experiences and lessons we have learned from the medical mountain rescue during the earthquake and the reconstruction,and reports here are to sum up our experiences from the medical mountain rescue operation in Yushu Earthquake and draw the lessons that we should learn. With the increasing of earthquake probability occurring in the Qinghai-Tibetan Plateau,we also should prepare against earthquake disasters and for further rescue training in the high mountains.

Ascent schedules,acute altitude illness,and altitude acclimatization:Observations on the Yushu Earthquake

During the Yushu Earthquake on April 14,2010,a large number of rescuers from sea level or lowlands ascended to the quake areas very rapidly or rapidly less than 24 h. However,Yushu Earthquake is the highest quake in the world at altitudes between 3 750 m and 4 878 m where is a serious hypoxic environment. A high incidence of acute altitude illness was found in the unacclimatized rescuers;the mountain rescue operation changed as "rescue the rescuers". Lesson from the Yushu Earthquake is that the occurrence of acute altitude illness may be closely related to the ascent schedules. This prompted us to study the relationship between ascent rate and the incidence and severity of acute altitude illness;five different groups were compared. The first group was 42 sea level male young soldiers who ascended to quake area very rapidly within 8 h at 4 000 m;the second group was 48 sea level male young soldiers who ascended to 4 000 m rapidly less than 18 h;the third group was 66 acclimatized medical workers from 2 261 m who ascended to 4 000 m rapidly within 12 h;the fourth group was 56 Tibetan medical workers from 2 800 m who ascended to 4 000 m rapidly within 8 h;the fifth group was 50 male sea level workers who ascended to 4 000 m gradually over a period of 4 d. The results showed that the sea level rescuers ascended to 4 000 m very rapidly or rapidly had the highest incidence of acute mountain sickness (AMS) with the greatest AMS scores and the lowest arterial oxygen saturation (SaO2);the sea level workers ascended to 4 000 m gradually had moderate incidence of AMS with moderate AMS scores and SaO2 values;whereas the acclimatized and adapted rescuers had the lowest incidence of AMS,lowest AMS scores and higher SaO2;especially none AMS occurred in Tibetan rescuers. AMS score is inversely related to the ascent rate (r=-0.24,p< 0.001). Additionally,acute altitude illness is significantly influenced by altitude acclimatization. The ascent rate is inversely re- lated to the period of altitude acclimatization whereas the time of perfect recovered from AMS is positively correlated to the time taken to acclimatize. Generally,the best means of preventing acute altitude illness is slow and gradual ascent to high altitude,as this allows time for establishing altitude acclimatization and tolerance to the hypoxic environment. However,during an emergency circumstance,such as mountain rescue operation,the rescuers must rapidly ascend to high altitude,so a series of preventive strategies including pre-acclimatization,using some prophylactic drugs and oxygen supplementary are sorely necessary.

High Arterial Oxygen Saturation in the Acclimatized Lowlanders Living at High Altitude

Blood oxygen saturation(SpO_(2))is a key indicator of oxygen availability in the body.It is known that a low SpO_(2)at high altitude is associated with morbidity and mortality risks due to physiological hypoxemia.Previously,it was proposed that the lowlander immigrants living at high altitude should have a lower SpO_(2)level compared to the highlander natives,but this proposal has not been rigorously tested due to the lack of data from the lowlander immigrants living at high altitude.In this study,we compared arterial oxygen saturation of 5929 Tibetan natives and 1034 Han Chinese immigrants living at altitudes ranging from 1120 m to 5020 m.Unexpectedly,the Han immigrants had a higher SpO_(2)than the Tibetan natives at the same high altitudes.At the same time,there is a higher prevalence of chronic mountain sickness in Han than in Tibetans at the same altitude.This result suggests that the relatively higher SpO_(2)level of the acclimatized Han is associated with a physiological cost,and the SpO_(2)level of Tibetans tends to be sub-optimal.Consequently,SpO_(2)alone is not a robust indicator of physiological performance at high altitude.

Associations between interleukin-1 polymorphisms and gastric cancers among three ethnicities

AIM:To investigate the associations between interleukin(IL)-1B and IL-1RN polymorphisms and gastric cancers among the Tibet,Hui and Han ethnicities.METHODS:Genomic DNA was extracted from peripheral blood of 210,205,and 202 healthy volunteers and from 155,158,and 197 gastric cancer patients from the Tibet,Hui,and Han populations,respectively.Polymorphisms in IL-1B and IL-1RN were analyzed by denaturing high-performance liquid chromatography.RESULTS:Carriers of the IL-1B-31 CC genotype had an increased risk of intestinal type gastric cancer [odds ratio(OR) = 2.17,P = 0.037] in the Tibet ethnicity.Carriers of the IL-1B 2/L genotype had an increased risk of both intestinal and diffuse types of gastric cancer(OR = 2.08,2.31,P = 0.007,0.016,respectively) in the Hui ethnicity.In the Han population,carriers of the IL-1B-31 CC,IL-1B-511CT,TT genotypes had increased risk of intestinal type gastric cancer(OR = 2.51,2.74,5.66,P = 0.005,0.002,0.000,respectively).CONCLUSION:IL-1B and IL-RN genotypes may differentially contribute to gastric cancer among the Tibet,Hui,and Han ethnicities in the Qinghai area of China.

Amplification of the miR-181c/d cluster is inversely correlated with PDCD4 expression in gastric cancer

miR-181c/d is dysregulated in gastric cancer(GC).We investigated the amplification and expression of miR-181c/d and its predicted target genes in GC.Amplification of miR-181c/d was quantified by genomic real-time PCR in GC and adjacent normal tissues,as well as the levels of mature miR-181c/d was performed by real-time PCR in the same tissues.The potential target genes of miR-181c/d were predicted using bioinformatics software.Expression of one potential target gene,PDCD4,was measured by semiquantitative RT-PCR,real-time PCR,and immunohistochemistry.Next,the relationship between miR181c/d expression and PDCD4 expression was analyzed.Results indicated that the amplification and expression of miR-181c/d were significantly higher in GC than in adjacent normal tissues(primary miR-181c/d,P\0.001;miR-181c,P=0.0344;miR-181d,P=0.0153),and there was a strong correlation between mature miR-181c/d and primary miR-181c/d.Thirty-two target genes were predicted,including PDCD4 which is a known tumor suppressor gene.Expression of PDCD4 was significantly down-regulated in GC as compared to adjacent normal tissues and was inversely correlated with miR-181c/d expression in GC(miR-181c and PDCD4:R=-0.496,P=0.008;miR-181d and PDCD4:R=-0.454,P=0.003).Therefore,miR-181c/d may play a pivotal role in the pathogenesis of GC by downregulating PDCD4 expression.

Correlation of DNA methylation patterns to the phenotypic features of Tibetan elite alpinists in extreme hypoxia

High altitude is an extreme environment that imposes hypoxic pressure on physiological processes,and natives living at high altitudes are more adaptive in certain physiological processes.So far,epigenetic modifications under extreme changes in hypoxic pressures are relatively less understood.Here,we recruit 32 Tibetan elite alpinists(TEAs),who have successfully mounted Everest(8848 m)at least five times.Blood samples and physiological phenotypes of TEAs and 32 matched non-alpinist Tibetan volunteers(non-TEAs)are collected for analysis.Genome-wide DNA methylation analysis identifies 23,202 differentially methylated CpGs(P_(adj)<0.05,|β|>0.1)between the two groups.Some differentially methylated CpGs are in hypoxia-related genes such as PPP1R13L,MAP3K7CL,SEPTI-9,and CUL2.In addition,Gene ontology enrichment analysis reveals several inflammation-related pathways.Phenotypic analysis indicates that 12 phenotypes are significantly different between the two groups.In particular,TEAs exhibit higher blood oxygen saturation levels and lower neutrophil count,platelet count,and heart rate.For DNA methylation association analysis,we find that two CpGs(cg16687447,cg06947206)upstream of PTEN were associated with platelet count.In conclusion,extreme hypoxia exposure leads to epigenetic modifications and phenotypic alterations of TEA,providing us clues for exploring the molecular mechanism underlying changes under extreme hypoxia conditions.

Seasonality and Sex-Biased Fluctuation of Birth Weight in Tibetan Populations

Birth weight(BW)is a key determinant of infant mortality.Previous studies have reported seasonal fluctuation of BW.However,the responsible environmental factors remain disputable.High-altitude environment provides a great opportunity to test the current hypotheses due to its distinctive climate conditions.We collected BW data of~9000 Tibetan singletons born at Lhasa(elevation:3660 m)from 2014 to 2018.Using regression models,we analyzed BW seasonality of highland Tibetans.Multivariate models with meteorological factors as independent variables were employed to examine responsible environmental factors accounting for seasonal variation.We compared BW,low-BW prevalence and sex ratio between high-land and lowland populations,and we observed a significant seasonal pattern of BW in Tibetans,with a peak in winter and a trough in summer.Notably,there is a marked sex-biased pattern of BW seasonality(more striking in males than in females).Sunlight exposure in the 3rd trimester and barometric pressure exposure in the 2nd trimester are significantly correlated with BW,and the latter can be explained by seasonal change of oxygen partial pressure.In particular,due to the male-biased BW seasonality,we found a more serious BW reduction and higher prevalence of low-BW in males,and a skewed sex ratio in highlanders.The infant BW of highland Tibetans has a clear pattern of seasonality.The winter BW is larger than the summer BW,due to the longer sunlight exposure during the late-trimester.Male infants are more sensitive to hypoxia than female infants during the 2nd trimester,leading to more BW reduction and higher mortality.