Effect of dissolved-oxygen on the flotation behavior of pyrite at high altitude area

With the continuous development of mineral resources to high altitude areas,the study of sulfide ore flotation in unconventional systems has been emphasized.There is a consensus that moderate oxidation of sulfide ore is beneficial to flotation,but the specific suitable dissolved oxygen value is inconclusive,and there are few studies on sulfide ore flotation under low dissolved oxygen environment at high altitude.In this paper,we designed and assembled an atmosphere simulation flotation equipment to simulate the flotation of pyrite at high altitude by controlling the partial pressure of N_(2)/O_(2) and dissolved oxygen under atmospheric conditions.X-ray photoelectron spec-troscopy(XPS),atomic force microscope(AFM),Fourier transform infrared spectrometer(FT-IR),UV-vis spectrophotometer,zeta po-tential,and contact angle measurements were used to reveal the effects of surface oxidation and agent adsorption on pyrite at high altitude(4600 m dissolved oxygen(DO)=4.0 mg/L).The results of pure mineral flotation indicated that the high altitude and low dissolved oxy-gen environment is favorable for pyrite flotation.Contact angle measurements and XPS analysis showed that the high altitude atmosphere nslows down the oxidation of pyrite surface,facilitates S_(n)^(2-)/S^(0) production and enhances surface hydrophobicity.Electrochemical calcula-tions and zeta potential analysis showed that the influence of atmosphere on the form of pyrite adsorption is small,and the different atmo-spheric conditions are consistent with dixanthogen electrochemical adsorption,with lower Zeta potential under high altitude atmosphere and significant potential shift after sodium isobutyl xanthate(SIBX)adsorption.The results of FT-IR,UV-vis,and AFM analysis showed that SIBX adsorbed more on the surface of pyrite under high altitude atmosphere and adsorbed on the surface in a mesh structure com-posed of column/block.The results of the experimental study revealed the reasons for the easy flotation of sulfide ores at high altitude with less collector dosage,and confirmed that the combined DO-pH regulation is beneficial to achieve more efficient flotation of pyrite.

Modification of streamer-to-leader transition model based on radial thermal expansion in the sphere-plane gap discharge at high altitude

Historically,streamer-to-leader transition studies mainly focused on the rod-plane gap and low altitude analysis,with limited attention paid to the sphere-plane gap at high altitude analysis.In this work,sphere-plane gap discharge tests were carried out under the gap distance of 5 m at the Qinghai Ultra High Voltage(UHV)test base at an altitude of 2200 m.The experiments measured the physical parameters such as the discharge current,electric field intensity and instantaneous optical power.The duration of the dark period and the critical charge of streamer-toleader transition were obtained at high altitude.Based on radial thermal expansion of the streamer stem,we established a modified streamer-to-leader transition model of the sphere-plane gap discharge at high altitude,and calculated the stem temperature,stem radii and the duration of streamer-to-leader transition.Compared with the measured duration of sphere-plane electrode discharge at an altitude of 2200 m,the error rate of the modified model was 0.94%,while the classical model was 6.97%,demonstrating the effectiveness of the modified model.From the comparisons and analysis,several suggestions are proposed to improve the numerical model for further quantitative investigations of the leader inception.

The cardiovascular system at high altitude:A bibliometric and visualization analysis

BACKGROUND When exposed to high-altitude environments,the cardiovascular system undergoes various changes,the performance and mechanisms of which remain controversial.AIM To summarize the latest research advancements and hot research points in the cardiovascular system at high altitude by conducting a bibliometric and visualization analysis.METHODS The literature was systematically retrieved and filtered using the Web of Science Core Collection of Science Citation Index Expanded.A visualization analysis of the identified publications was conducted employing CiteSpace and VOSviewer.RESULTS A total of 1674 publications were included in the study,with an observed annual increase in the number of publications spanning from 1990 to 2022.The United States of America emerged as the predominant contributor,while Universidad Peruana Cayetano Heredia stood out as the institution with the highest publication output.Notably,Jean-Paul Richalet demonstrated the highest productivity among researchers focusing on the cardiovascular system at high altitude.Furthermore,Peter Bärtsch emerged as the author with the highest number of cited articles.Keyword analysis identified hypoxia,exercise,acclimatization,acute and chronic mountain sickness,pulmonary hypertension,metabolism,and echocardiography as the primary research hot research points and emerging directions in the study of the cardiovascular system at high altitude.CONCLUSION Over the past 32 years,research on the cardiovascular system in high-altitude regions has been steadily increasing.Future research in this field may focus on areas such as hypoxia adaptation,metabolism,and cardiopulmonary exercise.Strengthening interdisciplinary and multi-team collaborations will facilitate further exploration of the pathophysiological mechanisms underlying cardiovascular changes in high-altitude environments and provide a theoretical basis for standardized disease diagnosis and treatment.

Study on Skin Care Efficacy of the Active Ingredients in Camellia Japonica Flowers at High and Low Altitudes

The active ingredients of Camellia japonica flowers(CJF)at high and low altitudes,as well as their skin care efficacy were compared.The dried red CJF at high and low altitudes were ultrasonically extracted with 70%ethanol,and these extracts were concentrated and then diluted to a constant volume.The content of total flavonoids,total polyphenols and total proteins was tested and analyzed.In addition,DPPH free radical scavenging,inhibition of the formation of advanced glycation end products,and inhibitory activity against elastase was measured to compare their skin care efficacy in anti-oxidation,anti-glycation,anti-wrinkling and firming.The results showed that,based on the dry weight of CJF,the content of total flavonoids and total proteins of the CJF at high altitude was approximately 1.5 times of the CJF at low altitude,while the content of total polyphenols was approximately 2.4 times that of the CJF at low altitude.The skin care efficacy of CJF at high altitude was significantly better than that of the CJF at low altitude.This work could provide theoretical basis for the selection and application of Camellia japonica flowers in the field of cosmetics.

Proteomic Analysis of the Small Intestine Reveals Adaptive Strategies for Energy Restriction of Phrynocephalus vlangalii at High Altitude

The environmental characteristics of hypothermia and hypoxia exert great selective pressure on the energy metabolism of high-altitude animals,especially the ectotherms.Current research on energy-limited adaptation of high-altitude ectotherms has focused on energy expenditures.However,the mechanisms of increasing energy intake in high-altitude ectotherms have been studied rarely.In order to investigate the adaptation mechanism of the small intestine,the key part of energy acquisition for animals,to energy limitation at high altitude in ectotherms,the gut proteins of Phrynocephalus vlangalii from high-and low-altitude populations were compared using label free proteomics.GO enrichment and KEGG pathway analysis showed that proteins associated with energy intake,such as those involved in oxidation-reduction processes,glutathione metabolism,oxidoreductase activity,cofactor binding,catalytic activity and metabolic pathways,were significantly up-regulated in high-altitude populations;while proteins associated with energy expenditure,such as immune responses and processes,membrane attack complexes,natural killer pathway and other immune-related processes,were significantly down-regulated in expression.

Changes of Na+ -K+ -ATPase activity and neuronal ultrastructure in cerebral cortex of rats exposed to a 5 000 m simulated high altitude

A model of high altitude cerebral hypoxia was made by two weeks' exposure to simulated high altitude of 5000 min 48 Wistar rats.The levels of Na+ -K+ -ATPase and Na+,K+ and water contents in the brain cortex were measured. The changes of neuronal ultrastructure were revealed with transmission electron microscope (TEM)examination. The results showed that the activity of Na+ -K+ -ATPase in the cerebral cortex reduced significantly (P<0. 01).The contents of Na+ and water in the cerebral cortex increased evidently (P<0.01).The damage of cortical neurons and neuronal swelling were very obvious under TEM.The experimental findings suggest that the depression of Na+-K+-ATPase activity and metabolic disorders of Na+ and K+ in the brain tissue might be an important factor for the occurrence and development of high altitude cerebral edema.

High Altitude Adaptation and Phylogenetic Analysis of Tibetan Horse Based on the Mitochondrial Genome

To investigate genetic mechanisms of high altitude adaptations of animals living in the Tibetan Plateau, three mitochondrial genomes （mt-genome） of Tibetan horses living in Naqu （4,500 m） of Tibetan, Zhongdian （3,300 m） and Deqin （3,100 m） of Yunnan province were sequenced. The structures and lengths of these three mt-genomes are similar to the Cheju horse, which is related to Tibetan horses, but little shorter than the Swedish horse. The pair-wise identity of these three horses on nucleotide level is more than 99.3%. When the gene encoding the mitochondrial protein of Tibetan horses was analyzed, we found that NADH6 has higher non-synonymous mutation rate in all of three Tibetan horses. This implies that NADH6 may play a role in Tibetan horses＇ high altitude adaptation. NADH6 is one of the subunits of the complex I in the respiratory chain. Furthermore, 7 D-loop sequences of Tibetan horse from different areas were sequenced, and the phylogeny tree was constructed to study the origin and evolutionary history of Tibetan horses. The result showed that the genetic diverse was high among Tibetan horses. All of Tibetan horses from Naqu were clustered into one clade, and Tibetan horses from Zhongdian and Deqin were clustered into others clades. The first molecular evidence of Tibetan horses indicated in this study is that Tibetan horse population might have multiple origins.

Satellite and high altitude platform-based inter-vehicle communications in vast and desolate areas

In order to solve the problem of inter-vehicle communication （IVC） in vast and desolate areas such as the desert and the Gobi, two vehicle network models are proposed. One is based on satellite communication and the other is based on high altitude platform （ HAP ） communication. The system outline and networking modes of the two models are described. In the satellite communication based model, all the vehicles are equipped with vehicle-bone satellite communication on the move terminals and the communication signals between vehicles are forwarded by satellite. In the high altitude platform-based model, the HAPs are equipped with base station facilities to form aerial base stations, and vehicles can communicate with each other via common terrestrial mobile communication devices. Some key parameters such as path loss, link loss and system capacity are also computed. The analysis shows that both the two models can satisfy the requirement of IVC in the descriptive environment.

Initial Analysis on the Effect of High-low Altitude Jet Stream on Heavy Precipitation in Guangxi

By using the routine observation data,a heavy precipitation process which happened in Guangxi on May 27,2006 was analyzed.The results that this heavy precipitation occurred in the common coordination weather system which included the high-altitude trough,the shear line and the ground cold front.The ascent branch of subtropical longitude circle circulation and the polar front jet stream longitude circle circulation had the important role for the formation of rainstorm area.The coupling effect of southerly jet,low-altitude westerly jet and high-altitude westerly jet in the boundary layer was the important reason of rainstorm occurrence.

Dynamic changes in peripheral blood-targeted miRNA expression profiles in patients with severe traumatic brain injury at high altitude

Background:The aim of this work is to detect and compare the peripheral blood mi RNA expression profiles in patients with severe traumatic brain injury(s TBI)2,12,24,48,and 72 h after injury at high altitude and to predict the target genes of differential expressed mi RNAs.Methods:Twenty s TBI patients from high-altitude areas were randomly selected according to the inclusion and exclusion criteria and were divided into five groups:the 2-h group,12-h group,24-h group,48-h group,and 72-h group.Peripheral blood mi RNA expression profiles were detected using real-time quantitative PCR(q RT-PCR).Results:The expression levels of mi R-18 a,mi R-203,mi R-146 a,mi R-149,mi R-23 b,and mi R-let-7 b in peripheral blood showed significant differences between the 2-h group and the 12-h group.The expression levels of mi R-203,mi R-146 a,mi R-149,mi R-23 b,and mi R-let-7 f in peripheral blood were up-regulated in the 24-h group.In the 48-h group,the expression levels of mi R-181 d,mi R-29 a,and mi R-18 b were upregulated.In the 72-h group,the expression levels of mi R-203,mi R-146 a,mi R-149,mi R-23 b,and mi R-let-7 f changed.The main target genes of the differentiation expressed mi RNAs were genes that regulate inflammatory responses,apoptosis,and DNA damage/repair.Conclusions:mi RNAs may be involved in the pathogenesis of s TBI by dynamically regulating the target genes that regulate inflammatory responses,apoptosis,and DNA damage/repair pathways.

Clinical,Laboratory and Imaging Features of High Altitude Pulmonary Edema in Tibetan Plateau

Objective To analyze characteristics of high altitude pulmonary edema(HAPE)in Chinese patients.Methods We performed a retrospective study of 98 patients with HAPE.We reviewed the medical records and summarized the clinical,laboratory and imaging characteristics of these cases,and compared the results on admission with those determined before discharge.Results Forty-eight(49.0%)patients developed HAPE at the altitude of 2800 m to 3000 m.Ninty-five(96.9%)patients were man.Moist rales were audible from the both lungs,and moist rales over the right lung were clearer than those over the left lung in fourteen patients.The white blood cells[(12.83±5.55)versus(8.95±3.23)×109/L,P=0.001)]as well as neutrophil counts[(11.34±3.81)versus(7.49±2.83)×109/L,P=0.001)]were higher,whereas the counts of other subsets of white blood cells were lower on admission than those after recovery(all P<0.05).Serum levels of alkaline phosphatase(115.8±37.6 versus 85.7±32.4 mmol/L,P=0.020),cholinesterase(7226.2±1631.8 versus 6285.3±1693.3 mmol/L,P=0.040),creatinine(85.2±17.1 versus 75.1±12.8 mmol/L,P=0.021),uric acid(401.9±114.2 versus 326.0±154.3 mmol/L,P=0.041),and uric glucose(7.20±1.10 versus 5.51±1.11 mmol/L,P=0.001)were higher,but carbondioxide combining power(CO2CP,26.7±4.4 versus 28.9±4.5 mmol/L,P=0.042)and serous calcium(2.32±0.13 versus 2.41±0.10 mmol/L,P=0.006)were lower on admission.Arterial blood gas results showed hypoxemia and respiratory alkalosis on admission.Conclusions In the present research,men were more susceptible to HAPE than women,and in the process of HAPE,the lesions of the right lung were more serious than those of the left lung.Some indicators of routine blood test and blood biochemistry of HAPE patients changed.

Serum testosterone levels and excessive erythrocytosis during the process of adaptation to high altitudes

Populations living at high altitudes （HAs）, particularly in the Peruvian Andes, are characterized by a mixture of subjects with erythrocytosis （16 g dl-1〈haemoglobin （Hb）≤21 gdl-1） and others with excessive erythrocytosis （EE） （Hb〉21 g dl-1）. Elevated haemoglobin values （EE） are associated with chronic mountain sickness, a condition reflecting the lack of adaptation to HA. According to current data, native men from regions of HA are not adequately adapted to live at such altitudes if they have elevated serum testosterone levels. This seems to be due to an increased conversion of dehydroepiandrosterone sulphate （DH EAS） to testosterone. Men with erythrocytosis at HAs show higher serum androstenedione levels and a lower testosterone/androstenedione ratio than men with EE, suggesting reduced 17beta-hydroxysteroid dehydrogenase （17beta-HSD） activity. Lower 17beta-HSD activity via A4-steroid production in men with erythrocytosis at HA may protect against elevated serum testosterone levels, thus preventing EE. The higher conversion of DHEAS to testosterone in subjects with EE indicates increased 17beta-HSD activity via the A5-pathway. Currently, there are various situations in which people live （human biodiversity） with low or high haemoglobin levels at HA. Antiquity could be an important adaptation component for life at HA, and testosterone seems to participate in this process.

High-altitude gastrointestinal bleeding:An observation in Qinghai-Tibetan railroad construction workers on Mountain Tanggula

AIM: To investigate the gastrointestinal bleeding (GIB) in people from lowland to high altitude and in workers on Mountain Tanggula and its causes as well as treatment and prophylaxis.METHODS: From 2001 to October 2003, we studied GIB in 13 502 workers constructing the railroad on Mountain Tanggula which is 4905 m above the sea level. The incidence of GIB in workers at different altitudes was recorded. Endoscopy was performed when the workers evacuated to Golmud (2808 m) and Xining (2261 m). The available data on altitude GIB were analyzed.RESULTS: The overall incidence of GIB was 0.49% in 13 502 workers. The incidence increased with increasing altitude. The onset of symptoms in most patients was within three weeks after arrival at high altitude. Bleeding manifested as hematemesis, melaena or hematochezia, and might be occult. Endoscopic examination showed that the causes of altitude GIB included hemorrhage gastritis, gastric ulcer, duodenal ulcer, and gastric erosion. Experimental studies suggested that acute gastric mucosal lesion (AGML) could be induced by hypoxic and cold stress, which might be the pathogenesis of altitude GIB. Those who consumed large amount of alcohol, aspirin or dexamethasone were at a higher risk of developing GIB. Persons who previously suffered from peptic ulcer or high-altitude polycythemia were also at risk of developing GIB. Early diagnosis, evacuation, and treatment led to early recovery. CONCLUSION: GIB is a potentially life threatening disease, if it is not treated promptly and effectively. Early diagnosis, treatment and evacuation lead to an early recovery. Death due to altitude GIB can be avoided if early symptoms and signs are recognized.

Over-starvation aggravates intestinal injury and promotes bacterial and endotoxin translocation under high-altitude hypoxic environment

AIM:To study whether over-starvation aggravates intestinal mucosal injury and promotes bacterial and endotoxin translocation in a high-altitude hypoxic environment.METHODS:Sprague-Dawley rats were exposed to hy-pobaric hypoxia at a simulated altitude of 7000 m for 72 h.Lanthanum nitrate was used as a tracer to detect intestinal injury.Epithelial apoptosis was observed with terminal deoxynucleotidyl transferase dUTP nick end labeling staining.Serum levels of diamino oxidase(DAO),malondialdehyde(MDA),glutamine(Gln),superoxide dismutase(SOD) and endotoxin were measured in intestinal mucosa.Bacterial translocation was detected in blood culture and intestinal homogenates.In addition,rats were given Gln intragastrically to observe its protective effect on intestinal injury.RESULTS:Apoptotic epithelial cells,exfoliated villi and inflammatory cells in intestine were increased with edema in the lamina propria accompanying effusion of red blood cells.Lanthanum particles were found in the intercellular space and intracellular compartment.Bacterial translocation to mesenteric lymph nodes(MLN) and spleen was evident.The serum endotoxin,DAO and MDA levels were significantly higher while the serum SOD,DAO and Gln levels were lower in intestine(P< 0.05).The bacterial translocation number was lower in the high altitude hypoxic group than in the high altitude starvation group(0.47±0.83 vs 2.38±1.45,P<0.05).The bacterial translocation was found in each organ,especially in MLN and spleen but not in peripheral blood.The bacterial and endotoxin translocations were both markedly improved in rats after treatment with Gln.CONCLUSION:High-altitude hypoxia and starvation cause severe intestinal mucosal injury and increase bacterial and endotoxin translocation,which can be treated with Gln.

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.

Correlation between blood pressure changes and AMS, sleeping quality and exercise upon high-altitude exposure in young Chinese men

Background: Excessive elevation of arterial blood pressure(BP) at high altitude can be detrimental to our health due to acute mountain sickness(AMS) or some AMS symptoms. This prospective and observational study aimed to elucidate blood pressure changes induced by exposure to high-altitude hypoxia and the relationships of these changes with AMS prevalence, AMS severity, sleep quality and exercise condition in healthy young men.Methods: A prospective observational study was performed in 931 male young adults exposed to high altitude at 3,700 m(Lhasa) from low altitude(LA, 500 m). Blood pressure measurement and AMS symptom questionnaires were performed at LA and on day 1, 3, 5, and 7 of exposure to high altitude. Lake Louise criteria were used to diagnose AMS. Likewise, the Athens Insomnia Scale(AIS) and the Epworth Sleepiness Scale(ESS) were filled out at LA and on day 1, 3, and 7 of exposure to high altitude.Results: After acute exposure to 3,700 m, diastolic blood pressure(DBP) and mean arterial blood pressure(MABP) rose gradually and continually(P【0.05). Analysis showed a relationship with AMS for only MABP(P【0.05) but not for SBP and DBP(P】0.05). Poor sleeping quality was generally associated with higher SBP or DBP at high altitude, although inconsistent results were obtained at different time(P【0.05). SBP and Pulse BP increased noticeably after high-altitude exercise(P【0.05).Conclusions: Our data demonstrate notable blood pressure changes under exposure to different high-altitude conditions: 1) BP increased over time. 2) Higher BP generally accompanied poor sleeping quality and higher incidence of AMS. 3) SBP and Pulse BP were higher after high-altitude exercise. Therefore, we should put more effort into monitoring BP after exposure to high altitude in order to guard against excessive increases in BP.

ANTI-HYPOXIA AND ANTI-OXIDATION EFFECTS OF AMINOPHYLLINE ON HUMAN WITH ACUTE HIGH-ALTITUDE EXPOSURE

Objective To investigate the anti-hypoxia and anti-oxidation effects of aminophylline on human with acute high- altitude exposure. Mothoda Totally 100 young male army members newly recruited from Sichuan province （400 meters above sea level） were enrolled. They were randomly divided into two groups： 50 in aminophylline group （A group） and 50 in control group （ C group）. A group and C group orally took aminophylline and placebo respectively for 10 days, 7 days before entering Lhasa （3 658 meters above sea level） by air and 3 days after it. Several parameters were measured at three time points： before drug taken, 7 days after drug taken, and 3 days after ascending high altitude. These parameters included serum levels of nitric oxide （NO）, superoxide dismutase （SOD）, catalase （CAT）, hydrogen dioxide （H2O2）, lactic acid （LA）, as well as arterial oxygen saturation （SO2）, arterial oxygen partial pressure （PaO2）, and arterial carbon dioxide partial pressure （PaCO2）. Statistical analysis was conducted to compare the difference between two groups with Stata 7.0 software system. Results There were no statistical differences between groups in hypoxia and oxidation indicators before and after drug taken in plain area. Three days after ascending high altitude, the serum levels of SOD, CAT, H202, LA, PaCO2 increased in both groups, yet to a much larger degree in C group than A group （P 〈0. 01 ） ; and NO, SO2 , PaO2 decreased more markedly in C group （ P 〈 0. 05 for NO, P 〈 0. 0001 for SO2 and PaO2 ）. Conclusion Aminophylline has significant anti-hypoxia and anti-oxidation effects at high altitude.

High altitude medicine in China in the 21st century Opportunities and challenges

China has the largest plateau, Qinghai-Tibet Plateau, where inhabited the most high altitude populations. Moreover, millions of people from plain areas come to the plateau for travel and work purposes and the number of the newcomers has been increasing every year. The hypoxic environment of plateau raised a series of related health issues in the new immigrants, so have created a special medical discipline- High Altitude Medicine. Over the past decades, researches on high altitude medicine have never being ceased in China, and lots of research findings have been reported. Application and practice of these achievements have greatly decreased the mobility and mortality of highaltitude diseases, however, there remained lots of questions to be elucidated. In view of this, the authors were granted a special project from the National Health and Family Planning Commission of China, and conducted a multi-center, prospective, on-scene high altitude medicine study for the acute mountain sickness. Some innovative findings were achieved, and the parameters for diagnosis and application conditions were proposed. Furthermore, the different diagnoses and treatment effects were compared, and a more standardized, reasonable scheme was drawn up. Regarding the unbalanced medical resources in the vast high altitude area, an application system for the public and the army has been established. In the 21 st century, innovations in China and novel research approaches have provided great opportunities for the development of high altitude medicine. It is believed that the researchers in China are able to catch the opportunities and address the challenges.

Endothelial Nitric Oxide Synthase Gene Polymorphisms Associated with Susceptibility to High Altitude Pulmonary Edema in Chinese Railway Construction Workers at Qinghai-Tibet over 4500 Meters above Sea Level

Objective To examine whether the polymorphisms of endothelial nitric oxide synthase (eNOS) gene are associated with the susceptibility to high altitude pulmonary edema (HAPE) in Chinese railway construction workers at Qinghai-Tibet where the altitude is over 4 500 m above sea level. Methods A case-control study was conducted including 149 HAPE patients in the construction workers and 160 healthy controls randomly recruited from their co-workers, matching the patients in ethnicity, age, sex, lifestyle, and working conditions. Three polymorphisms of eNOS gene, T-786C in promoter, 894G/T in exon 7, and 27bp variable number tandem repeat (VNTR) in intron 4, were genotyped using polymerase chain reaction (PCR) and confirmed with DNA sequencing. Results The frequencies of 894T allele and heterozygous G/T of the 894G/T variant were significantly higher in HAPE patients group than in the control group (P=0.0028 and P=0.0047, respectively). However, the frequencies of the T-786C in promoter and the 27bp VNTR in intron 4 were not significantly different between the two groups. Haplotypic analysis revealed that the frequencies of two haplotypes (H3,T-T-b, b indicates 5 repeats of 27 bp VNTR; H6, C-G-a, a indicates 4 repeats of 27 bp VNTR) were significantly higher in HAPE patients (both P<0.0001). On the contrary, the frequencies of H1 (T-G-b) and H2 (T-G-a) were lower in HAPE patients than in healthy controls (both P<0.001). Conclusions Two haplotypes (T-T-b and C-G-a) may be strongly associated with susceptibility to HAPE. Compared with the individual alleles of eNOS gene, the interaction of multiple genetic markers within a haplotype may be a major determinant for the susceptibility to HAPE.

Aerobic bacterial flora of the normal conjunctiva at high altitude area of Shimla Hills in India:a hospital based study

AIM:To study the normal aerobic conjunctival flora in lower to mid Himalayan region of Shimla Hills.METHODS:Samples from normal conjunctiva of 200 individuals above the age of 13 years who visited Indira Gandhi Medical College Hospital Shimla for refraction or cataract surgery were taken by anaesthetising the conjunctival sac with sterile 4% Xylocaine solution.Samples were obtained by gently rubbing lower fornix with a sterile cotton wool swab moistened with normal saline and keeping the eye lids wide apart to avoid contamination from lid margins.It was immediately inoculated in Brain Heart infusion and subjected to standard aerobic culture and identification techniques.RESULTS:Totally,72 eyes(36%) conjunctival sacs were sterile.Predominant aerobes isolated were Staphylococcus spp.in 120(60%) followed by Haemophilus in 16(8%),diphtheroids in 10(5%),and Escherichia coli(E.coli) in 4(2%).A single aerobe was isolated from 98 eyes(49%) while 30 eyes(15%) yielded more than 1 aerobe.Staphylococcus epidermidis(S.epidermidis) was the most common bacterium,found alone in 58 eyes(29%) and in combination with another aerobe in 30 eyes(15%),followed by Staphylococcus aureus(S.aureus) in 18(9%) and 10 eyes(5%) respectively.CONCLUSION:S.epidermidis is the most common commensal organism followed by Haemophilus species.diphtheroids occupied the third position which otherwise are found more abundantly in literature.Pathogens like S.aureus,Staphylococcus citreus and E.coli were also found.Therefore,preoperative administration of topical broad spectrum antibiotics is extremely important in prophylaxis against ocular infection.The variation in microflora of normal conjunctiva in this part of world can be attributed to geographical,climatic and ethnic characteristics of the population under study.