High-flow nasal cannula oxygen reduced hypoxemia in patients undergoing gastroscopy under general anesthesia at ultra-high altitude: a randomized controlled trial.

BACKGROUND: Hypoxemia can occur in people at ultra-high altitude (above 3500 m) even at rest, and patients undergoing gastroscopy under general anesthesia have higher risk of hypoxemia. Supplementary oxygen via standard nasal cannula (SNC) is the standard of care for most patients who undergo gastroscopy under general anesthesia, which provides oxygen flow up to 15 L/min. High-flow nasal cannula (HFNC) could deliver oxygen at a rate up to 60 L/min, which is recommended by the American Society of Anesthesiologists Practice Guidelines. We speculated that the benefit with HFNC is more prominent in high-altitude areas, and aimed to compare the incidence of hypoxemia during gastroscopy under general anesthesia at ultra-high altitude with oxygen supply via either HFNC or SNC. METHODS: The trial was registered at at Chinese Clinical Trial Registry (ChiCTR2100045513; date of registration on 18/04/2021). Adult patients undergoing gastroscopy with anesthesia (estimated duration of anesthesia at ≥ 15 min) were randomized at a 1:1 ratio to receive HFNC oxygen or SNC oxygen. The primary outcome was hypoxemia (SpO2 < 90% for any duration). Secondary outcomes included severe hypoxemia (SpO2 < 75% for any duration or SpO2 < 90% but ≥ 75% for ≥ 60 s) and hypotension, as defined by reduction of mean arterial blood pressure by ≥ 25% from the baseline. RESULTS: A total of 262 patients were enrolled: 129 in the HFNC group and 133 in the SNC group. All patients received the designated intervention. Student's t-test, Mann-Whitney U test and χ2 test were employed in the study. The rate of hypoxemia was 9.3% (12/129) in the HFNC group versus 36.8% (49/133) in the SNC group [risk ratio (95% confidence interval): 0.25(0.14-0.45); P < 0.001). The HFNC group also had lower rate of severe hypoxemia [0.0% (0/129) versus 11.3% (15/133); risk ratio (95% confidence interval): 0.03(0.00-0.55); P < 0.001, respectively]. The rate of hypotension did not differ between the 2 groups [22.5% (29/129) in HFNC group versus 21.1% (28/133) in SNC group; risk ratio (95% confidence interval): 1.07(0.67-1.69) ; P = 0.779]. CONCLUSION: HFNC oxygen reduced the incidence of hypoxemia during anesthesia in adult patients undergoing gastroscopy at ultra-high altitude.

Environmental fate of microplastics in high-altitude basins: the insights into the Yarlung Tsangpo River Basin.

Microplastics (MPs) have been found in remote high-altitude areas, but the main source and migration process remained unclear. This work explored the characteristics and potential sources of MPs in the Yarlung Tsangpo River Basin. The average abundances of MPs in water, sediment, and soil samples were 728.26 ± 100.53 items/m3, 43.16 ± 5.82 items/kg, and 61.92 ± 4.29 items/kg, respectively, with polypropylene and polyethylene as the main polymers. The conditional fragmentation model revealed that the major source of MPs lower than 4000 m was human activities, while that of higher than 4500 m was atmospheric deposition. Community analysis was further conducted to explore the migration process and key points of MPs among different compartments in the basin. It was found that Lhasa (3600 m) and Shigatse (4100 m) were vital sources of MPs inputs in the midstream and downstream, respectively. This work would provide new insights into the fate of MPs in high-altitude areas.

Metabolites and gene expression in the myocardium of fasting rats in an acute hypoxic environment.

With the rising demand for entry to extremely high altitudes (HAs), rapid adaptability to extremely hypoxic environments is a challenge that we need to explore. Fasting was used to evaluate acute hypoxia tolerance at HA and was proven to be an effective method for improving the survival rate at extreme HA. Our experiments also showed that fasting pretreatment for 72 h significantly increased the 24 h survival rate of rats at 7620 m from 10 to 85% and protected the myocardium cells of rats. Here, we compared the metabolites and gene expression in the myocardium of SD rats pretreated with fasting and nonfasting at normal altitude and extreme HA. Our findings demonstrated that the dynamic contents of detected differential metabolites (DMs) between different rat groups were consistent with the expression of differentially expressed genes (DEGs), and DM clusters also showed strong correlations with DEG clusters. DM clusters related to amino acids and lipids were significantly lower in the fasting groups, and the correlated DEG clusters were enriched in mitotic pathways, including CDK1, CDC7, NUF2, and MCM6, suggesting that fasting can attenuate mitotic processes in cardiac tissues and reduce the synthesis of amino acids and lipids. L-Glutamine-related metabolites were particularly low at extreme HA without pretreatment but were normal in the fasting groups. The DEGs in the cluster related to L-glutamine-related metabolites were enriched for T-cell receptor V(D)J recombination, the Hippo signaling pathway, the Wnt signaling pathway, the cGMP-PKG signaling pathway, and the mTOR signaling pathway and were significantly downregulated, indicating that the content of L-glutamine decreased at extreme HA, while fasting increased it to adapt to the environment. Moreover, abundant fatty acids were detected when rats were exposed to extreme HA without pretreatment. Our study revealed the fasting and hypoxic environment-related factors in SD rats and provided new insights into the genetic and molecular characteristics in the myocardium, which is critical to developing more potential rapid adaptation methods to extreme HA.

Clinical characteristics of venous thromboembolism onset from severe high altitude pulmonary edema in plateau regions.

BACKGROUND: To investigate venous thromboembolism (VTE) in hospitalized patients with severe high altitude pulmonary edema (HAPE), we performed a single center retrospective study to evaluate its clinical characteristics, prognosis, and potential thromboprophylaxis strategies in a large referral and treatment center in plateau regions. METHODS: We studied a total of 18 patients with severe HAPE from January 1, 2012 to December 31, 2021. Demographic and clinical data, laboratory data, including ultrasound scans of the lower extremities and cardiac ultrasound, and computed tomographic pulmonary angiography (CTPA) variables were obtained, and comparisons were made between groups with and without VTE. RESULTS: Of the 18 patients hospitalized with severe HAPE (age 43 (range, 34-54) years, 14 [77.8%] men), 7 patients developed VTE (38.9%), including 5 with deep vein thrombosis (DVT) and pulmonary embolism (PE), 2 of whom had DVT only. Eighteen patients are all firstly rapid ascent to high altitudes which the mean altitude was 3700 m (3656-4050 m). Compared with patients who did not have VTE, patients with VTE had a longer time in hospital (13 [11, 19] versus 9 [7, 12]; P = 0.027), respiratory failure (6 [85.7%] versus 2 [18.2%]; P = 0.013), the shortened APTT (21.50 [19.00, 27.50] versus 26.30 [24.80, 30.10]; P = 0.044) and the higher level of D-dimer (7.81 [4.62, 9.60] versus 2.90 [1.75, 3.37]; P = 0.003). The proportion of thromboprophylaxis is too low in our cohort which 2 of 18 (11.1%) patients were given VTE prophylaxis. There was no statistically significant difference between the VTE and non-VTE groups (0 [0.0%] versus 2 [18.2%]; P = 0.497). CONCLUSIONS: The prevalence of VTE is high in hospitalized patients with severe high altitude pulmonary edema (HAPE). Prophylaxis for venous thromboembolism may be protective in severe HAPE patients after admission. Our data seem to suggest that VTE is probably an additional prognostic factors in patients with severe HAPE.

Risk factors for mortality in patients with acute exacerbation of cor pulmonale in plateau.

BACKGROUND: The risk factors for mortality might differ between patients with acute exacerbation of chronic pulmonary heart disease in plains and plateaus, while there is a lack of evidence. METHOD: Patients diagnosed with cor pulmonale at Qinghai Provincial People's Hospital were retrospectively included between January 2012 and December 2021. The symptoms, physical and laboratory examination findings, and treatments were collected. Based on the survival within 50 days, we divided the patients into survival and death groups. RESULTS: After 1:10 matching according to gender, age, and altitude, 673 patients were included in the study, 69 of whom died. The multivariable Cox proportional hazards analysis showed that NYHA class IV (HR = 2.03, 95%CI: 1.21-3.40, P = 0.007), type II respiratory failure (HR = 3.57, 95%CI: 1.60-7.99, P = 0.002), acid-base imbalance (HR = 1.82, 95%CI: 1.06-3.14, P = 0.031), C-reactive protein (HR = 1.04, 95%CI: 1.01-1.08, P = 0.026), and D-dimer (HR = 1.07, 95%CI: 1.01-1.13, P = 0.014) were risk factors for death in patients with cor pulmonale at high altitude. Among patients living below 2500 m, cardiac injury was a risk factor for death (HR = 2.47, 95%CI: 1.28-4.77, P = 0.007), while no significant association was observed at ≥ 2500 m (P = 0.057). On the contrary, the increase of D-dimer was only a risk factor for the death of patients living 2500 m and above (HR = 1.23, 95% CI: 1.07-1.40, P = 0.003). CONCLUSION: NYHA class IV, type II respiratory failure, acid-base imbalance, and C- reactive protein may increase the risk of death in patients with cor pulmonale. Altitude modified the association between cardiac injury, D-dimer, and death in patients with cor pulmonale.

Supraglottic jet oxygenation and ventilation decreased hypoxemia during gastrointestinal endoscopy under deep sedation at high altitudes: a randomized clinical trial.

BACKGROUND: Hypobaric hypoxia is common at high altitudes. Whether this exacerbates hypoxia during procedural sedation and whether hypoxia can be alleviated by the use of supraglottic jet oxygenation and ventilation (SJOV) are unknown. This study aimed to compare the incidence of hypoxia during gastrointestinal endoscopy under deep sedation at high altitudes with oxygen supply techniques using either a nasal cannula or SJOV. METHODS: This study was conducted from April 2022 to July 2022 in a tertiary hospital located 3650 m above sea level. Adult patients scheduled for routine gastrointestinal endoscopy under sedation were enrolled and randomized 1:1 to receive SJOV or a nasal cannula during sedation. Moderate hypoxia was the primary outcome, defined as an SPO2 of 75-89% for < 60 s. The secondary outcomes were respiratory-, cardiovascular-, and SJOV-related complications. The influence of characteristics regarding acclimatization to high altitudes (Tibetan ethnic group and erythrocytosis) on the occurrence of hypoxia was analyzed. RESULTS: None of the patients were lost to follow-up. A total of 72 patients were included in the analysis (36 patients in each group). There were 20 (27.8%) patients who experienced moderate hypoxia events. Significantly fewer hypoxic events occurred in the SJOV group than in the nasal cannula group [3 (8.3%) vs. 17 (47.2%), absolute risk difference (95% CI): - 38.9 (- 57.5, - 20.2) %, risk ratio (RR, 95% CI): 0.18 (0.06, 0.55), P < 0.001]. Significantly fewer patients in the SJOV group experienced mild hypoxia (P < 0.001) and severe hypoxia (P = 0.002). No serious adverse events occurred in either of the groups. The Tibetan ethnic group (P = 0.086) and erythrocytosis (P = 0.287) were not associated with the occurrence of hypoxia events. CONCLUSIONS: The incidence of hypoxia was lower with SJOV than with nasal cannula in patients undergoing gastrointestinal endoscopy under deep sedation at high altitudes. The Tibetan ethnic group and erythrocytosis did not influence the occurrence of hypoxia. TRIAL REGISTRATION: This study was registered at ClinicalTrials.gov (NCT05304923) before enrollment by Dr. Yi Feng on 31/03/2022.

Genetic mechanism of adaptive evolution: the example of adaptation to high altitudes.

Since Darwin's time, elucidating the mechanism of adaptive evolution has been one of the most important scientific issues in evolutionary biology and ecology. Adaptive evolution usually means that species evolve special phenotypic traits to increase fitness under selective pressures. Phenotypic adaptation can be observed at different hierarchical levels of morphology, physiology, biochemistry, histology, and behavior. With the breakthroughs of molecular biology and next-generation sequencing technologies, mounting evidence has uncovered the genetic architecture driving adaptive complex phenotypes. Studying the molecular genetic mechanisms of evolutionary adaption will enable us to understand the forces shaping biodiversity and set up genotype-phenotype-environment interactions. Genetic bases of adaptive evolution have been explained by multiple hypotheses, including major-effect genes, supergenes, polygenicity, noncoding regions, repeated regions, and introgression. The strong selection pressure exerted by high-altitude extreme environments greatly promotes the occurrence of phenotypic and genetic adaptation in species. Studies on multi-omics data provide new insights into adaptive evolution. In this review, we systematically summarize the genetic mechanism of adaptive evolution, research progress in adaptation to high-altitude environmental conditions, and existing challenges and discuss the future perspectives, thereby providing guidance for researchers in this field.

Summer seasonal prevalence of Culicoides species from pre-alpine areas in Switzerland.

Biting midges (Diptera: Ceratopogonidae) are arthropods of veterinary importance since they can transmit pathogens and cause severe allergic dermatitis in horses. Very little is known about the species at higher altitudes and their seasonal dynamics. In this work, adult Culicoides were collected with Onderstepoort UV-light suction traps (OVI) from June to September 2016 at two areas situated at around 1600 m asl (pre-alpine area I, 2 farms) and 2030 m asl (pre-alpine area II, 1 farm) in the Canton of Grisons (south-east Switzerland). Overall, 17 049 Culicoides were collected, including 871 parous females. A total of 50 individuals/trap/night (n = 1050) were identified to species (17 species) by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) or by polymerase chain reaction (PCR) and sequencing. The remaining 15 128 Culicoides were classified to species groups' level. Culicoides obsoletus (Meigen, 1818), a multivoltine species, was mainly present at 1600 m asl, whereas at high altitudes (2030 m asl), C. grisescens Edwards, 1939 I&II were the most abundant species. In particular, C. grisescens II, which seems to be univoltine, occurred later in the season but significantly increasing over time. Species diversity was higher at pre-alpine I area (n = 16 species) compared to pre-alpine II (n = 10 species).

Iron supplementation at high altitudes induces inflammation and oxidative injury to lung tissues in rats.

Exposure to high altitudes is associated with hypoxia and increased vulnerability to oxidative stress. Polycythemia (increased number of circulating erythrocytes) develops to compensate the high altitude associated hypoxia. Iron supplementation is, thus, recommended to meet the demand for the physiological polycythemia. Iron is a major player in redox reactions and may exacerbate the high altitudes-associated oxidative stress. The aim of this study was to explore the potential iron-induced oxidative lung tissue injury in rats at high altitudes (6000ft above the sea level). Iron supplementation (2mg elemental iron/kg, once daily for 15days) induced histopathological changes to lung tissues that include severe congestion, dilatation of the blood vessels, emphysema in the air alveoli, and peribronchial inflammatory cell infiltration. The levels of pro-inflammatory cytokines (IL-1ß, IL-6, and TNF-α), lipid peroxidation product and protein carbonyl content in lung tissues were significantly elevated. Moreover, the levels of reduced glutathione and total antioxidant capacity were significantly reduced. Co-administration of trolox, a water soluble vitamin E analog (25mg/kg, once daily for the last 7days of iron supplementation), alleviated the lung histological impairments, significantly decreased the pro-inflammatory cytokines, and restored the oxidative stress markers. Together, our findings indicate that iron supplementation at high altitudes induces lung tissue injury in rats. This injury could be mediated through excessive production of reactive oxygen species and induction of inflammatory responses. The study highlights the tissue injury induced by iron supplementation at high altitudes and suggests the co-administration of antioxidants such as trolox as protective measures.

Review of Athletic Guidelines for High-Altitude Training and Acclimatization.

Ramchandani, Rashi, Ioana Tereza Florica, Zier Zhou, Aziz Alemi, and Adrian Baranchuk. Review of athletic guidelines for high-altitude training and acclimatization. High Alt Med Biol. 00:000-000, 2024. Introduction: Exposure to high altitude results in hypobaric hypoxia with physiological acclimatization changes that are thought to influence athletic performance. This review summarizes existing literature regarding implications of high-altitude training and altitude-related guidelines from major governing bodies of sports. Methods: A nonsystematic review was performed using PubMed and OVID Medline to identify articles regarding altitude training and guidelines from international governing bodies of various sports. Sports inherently involving training or competing at high altitude were excluded. Results: Important physiological compensatory mechanisms to high-altitude environments include elevations in blood pressure, heart rate, red blood cell mass, tidal volume, and respiratory rate. These responses can have varying effects on athletic performance. Governing sport bodies have limited and differing regulations for training and competition at high altitudes with recommended acclimatization periods ranging from 3 days to 3 weeks. Discussion: Physiological changes in response to high terrestrial altitude exposure can have substantial impacts on athletic performance. Major sport governing bodies have limited regulations and recommendations regarding altitude training and competition. Existing guidelines are variable and lack substantial evidence to support recommendations. Additional studies are needed to clarify the implications of high-altitude exposure on athletic ability to optimize training and competition.

High myopia at high altitudes.

Background: Optic nerve sheath diameter (ONSD) increases significantly at high altitudes, and is associated with the presence and severity of acute mountain sickness (AMS). Exposure to hypobaria, hypoxia, and coldness when hiking also impacts intraocular pressure (IOP). To date, little is known about ocular physiological responses in trekkers with myopia at high altitudes. This study aimed to determine changes in the ONSD and IOP between participants with and without high myopia (HM) during hiking and to test whether these changes could predict symptoms of AMS. Methods: Nine participants with HM and 18 without HM participated in a 3-day trek of Xue Mountain. The ONSD, IOP, and questionnaires were examined before and during the trek of Xue Mountain. Results: The ONSD values increased significantly in both HM (p = 0.005) and non-HM trekkers (p = 0.018) at an altitude of 1,700 m. In the HM group, IOP levels were greater than those in the non-HM group (p = 0.034) on the first day of trekking (altitude: 3,150 m). No statistically significant difference was observed between the two groups for the values of ONSD. Fractional changes in ONSD at an altitude of 1,700 m were related to the development of AMS (r pb = 0.448, p = 0.019) and the presence of headache symptoms (r pb = 0.542, p = 0.004). The area under the ROC curve for the diagnostic performance of ONSD fractional changes at an altitude of 1,700 m was 0.859 for predicting the development of AMS and 0.803 for predicting the presence of headache symptoms. Conclusion: Analysis of changes in ONSD at moderate altitude could predict AMS symptoms before an ascent to high altitude. Myopia may impact physiological accommodation at high altitudes, and HM trekkers potentially demonstrate suboptimal regulation of aqueous humor in such environments.

Lipid profiles and their relation to glycemic control in Saudi Arabia: The role of altitudes and environmental factor.

Background: The height from sea levels, environmental factors, human-environment interactions, and lifestyle significantly influence the lipid profile and glycemic control of a population. Objective: This study aims to explore the influence of altitude on lipid profiles and glycemic control among the Saudi population at sea level and high altitude. Methods: In this retrospective cross-sectional study, a large dataset of patients of both gender and over 30 years old attending internal medicine clinics from two different regions at different heights from sea level, Jeddah (sea level) and Asir region (high altitudes) and referred to commercial laboratories for glycated haemoglobin (HbA1c) and lipids profile. Results: Compared to the Asir region, the Jeddah region had significantly higher mean values for fasting blood sugar (FBG), total cholesterol (TC), low-density lipoprotein (LDL-C), and triglycerides (TG) (P < 0.05). Every 1 mg/dL increase in FBG results in a 0.662 mg/dL increase in TG from the Jeddah region. However, it was a 0.318 mg/dL increase in TG from the Asir region. HbA1c demonstrated a significant (P < 0.05) strong positive correlation with TC, low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), and lipid ratio. FBG levels were also associated with a high level of TC/HDL-C (ß = 0.137 95% confidence interval [CI]: 0.11-0.21; P < 0.05), LDL-C/high-density lipoprotein cholesterol (HDL-C) (ß = 0.50; 95% CI: 0.31-1.49; P < 0.05), and TG/HDL-C (ß = 0.14; 95% CI = 0.12-0.15; P < 0.05) in Jeddah region. However, significantly high blood pressure was observed in the population from high altitudes. Conclusion: Our results demonstrated a significant positive correlation between lipid profile and glycemic control with high prevalence at sea level.

Maximal pulmonary ventilation and lactate affect the anaerobic performance in young women exposed to hypobaric hypoxia.

Background: Athletes, tourists, and mining workers from all over the world ascend daily to an altitude greater than 3.000 meters above sea level to perform different activities, all of which demand physical effort. A ventilation increase is the first mechanism once the chemoreceptors perceive hypoxia, and is key to maintaining blood oxygen levels during acute exposure to high altitudes and to buffering lactic acidosis during exercise. It has been observed that gender is a variable that can influence the ventilatory response. Still, the available literature is limited due to the few studies considering women as study subjects. The influence of gender on anaerobic performance and its effects under high altitudes (HA) environments have been poorly studied. Objective: The objectives of this study were to evaluate anaerobic performance in young women exposed to high altitudes and to compare the physiological response to multiple sprints between women and men measured by ergospirometry. Methodology: Nine women and nine men (22.9 ± 3.2 years old) carried out the multiple-sprint anaerobic tests under two conditions, sea level and high altitudes. Results: In the first 24 h of exposure to a high altitudes, lactate levels were higher in women than those in men (2.57 ± 0.4 Mmol/L, 2.18 ± 0.3 Mmol/L, respectively; p < 0.05). Second, women had a decreased ventilatory response in exposure to high altitudes compared to men (p > 0.005). Third, there is a positive correlation between lactate levels prior to an anaerobic test and the ventilatory response developed by subjects at high altitudes (R2 = 0.33, slope = -41.7, and p < 0.05). Lastly, this ventilatory response can influence VO2peak (R2 = 0.60, slope = 0.02, and p < 0.001). Conclusion: This study provides insights into the mechanisms behind the reduced respiratory capacity observed in women during an anaerobic exercise test at high altitudes. An acute response to HA showed a greater work of breathing and increased the drive ventilatory response. It is possible to postulate the differences in the fatigue-induced metaboreflex of the respiratory muscles and aerobic-anaerobic transition between genders. These results on multiple sprint performance and the influences of gender in hypoxic environments deserve further investigation.

Neurodynamics of Awareness Detection in Tibetan Immigrants: Evidence from Electroencephalography Analysis.

The psychological effects of long-term exposure to high-altitude environments have attracted great attention. These effects are usually attributed to the diminished cognitive resources due to high-altitude exposure. This study employed electroencephalography (EEG) to investigate the effects of exposure duration on awareness detection tasks. Neither reaction time nor accuracy showed the direct effects of the exposure duration, so did the model indexes obtained from drift diffusion model analysis. However, event-related potentials (ERP) analysis revealed that exposure duration was associated with changes in the visual awareness negativity (VAN) and the late positivity (LP) components, which in turn affected reaction time. Specifically, longer exposure durations were associated with lower VAN and higher LP, resulting in shorter reaction times and greater drift rate. In contrast to previous studies, the reverse relationship between VAN and LP may reflect a compensatory response to the reduced cognitive resources caused by high-altitude exposure. Additionally, increased LP and shorter reaction times with exposure duration may reflect a resistance to the high-altitude environment. We also conducted time-frequency analysis and found that theta power did not vary with exposure duration, suggesting that the reduction in cognitive resources remains stable in these individuals over time. Overall, our study provides new insights into the dynamic effects of high-altitude environments on awareness detection in the presence of reduced cognitive resources.

Radiation environment in high-altitude Antarctic plateau: Recent measurements and model studies.

Polar regions are the most exposed to secondary particles and radiation produced by primary cosmic rays in the atmosphere, because naturally they are with marginal geomagnetic shielding. In addition, the secondary particle flux contributing to the complex radiation field is enhanced at high-mountain altitudes compared to sea level because of the reduced atmospheric attenuation. At present, there are very few systematic experimental measurements of environmental dose at high southern latitudes, specifically at high-altitude region. Here, we report a campaign of measurements with different devices, that is passive and Liulin-type dosimeters, of the radiation background at high-mountain Antarctic station Vostok (3488 m above sea level, 78° 27' S; 106° 50' E). We compare the measurements with a Monte Carlo-based model for the propagation of the cosmic rays through the atmosphere and assessment of the radiation field in the atmosphere. We employed the model to estimate the radiation dose at Vostok station during the ground-level enhancement at 28 October 2021. As in previous studies by other teams, we show that the annual dose equivalent at high-altitude Antarctic facilities can significantly exceed the limit of 1 mSv established for the general population by the ICRP.

Diversity of endophytic bacterial and fungal microbiota associated with the medicinal lichen Usnea longissima at high altitudes.

Endophytic microbial communities of lichen are emerging as novel microbial resources and for exploration of potential biotechnological applications. Here, we focused on a medicinal lichen Usnea longissima, and investigated its bacterial and fungal endophytes. Using PacBio 16S rRNA and ITS amplicon sequencing, we explored the diversity and composition of endophytic bacteria and fungi in U. longissima collected from Tibet at five altitudes ranging from 2,989 to 4,048 m. A total of 6 phyla, 12 classes, 44 genera, and 13 species of the bacterial community have been identified in U. longissima. Most members belong to Alphaproteobacteria (42.59%), Betaproteobacteria (33.84%), Clostridia (13.59%), Acidobacteria (7%), and Bacilli (1.69%). As for the fungal community, excluding the obligate fungus sequences, we identified 2 phyla, 15 classes, 65 genera, and 19 species. Lichen-related fungi of U. longissima mainly came from Ascomycota (95%), Basidiomycota (2.69%), and unidentified phyla (2.5%). The presence of the sequences that have not been characterized before suggests the novelty of the microbiota. Of particular interest is the detection of sequences related to lactic acid bacteria and budding yeast. In addition, the possible existence of harmful bacteria was also discussed. To our best knowledge, this is the first relatively detailed study on the endophytic microbiota associated with U. longissima. The results here provide the basis for further exploration of the microbial diversity in lichen and promote biotechnological applications of lichen-associated microbial strains.

Vitamin D Levels and Cardiometabolic Markers in Indigenous Argentinean Children Living at Different Altitudes.

The objective of this study was to assess the association between vitamin D and cardiometabolic markers in 2 indigenous communities from similar ethnic backgrounds, but living at different altitudes. A cross-sectional study compared 152 (72 females) indigenous schoolchildren from San Antonio de los Cobres (SAC), 3750 m above sea level, with 175 (86 females) from Chicoana (CH), 1400 m above sea level, mean age 9 years. Anthropometry, blood pressure, lipids, glucose, insulin, and vitamin D were assessed in spring season. The prevalence of children's overweight/obesity was significantly lower in SAC, 9.2% (13), than in CH, 41.5% (71). There was a significantly higher prevalence of vitamin D deficiency (<20 ng/mL) in SAC (n = 103, 67.7%) than in CH (n = 62, 36.3%). SAC showed an inverse correlation between vitamin D and insulinemia (r = -0.17, P < .05), whereas CH showed an inverse correlation between vitamin D and systolic blood pressure (r = -0.19, P < .05), z-BMI (body mass index; r = -0.25, P < .01), triglycerides (r = -0.15, P < .05), glucose (r = -0.35, P < .05), and insulinemia (r = -0.24, P < .01). Multiple linear regression analysis showed that vitamin D (ß = -.47; R 2 = .21) was significantly associated with SAC location, adjusted for confounding variables. Vitamin D levels were significantly and directly associated with altitude and inversely with metabolic markers, suggesting that populations living at high altitudes are at higher risk for future cardiovascular diseases.

Touching the Sky: Coccinellids (Coleoptera: Coccinellidae) at High Altitudes in South America.

Records of extreme altitudes where several coccinellid species from South America inhabit the Andes of Argentina, Bolivia, Chile, Colombia, Ecuador, and Peru are provided. After an intensive review of several entomological collections and literature, records for 35 species with at least one location over 3500-m elevation were obtained, including the genera Cycloneda (ten species), Eriopis (15 species and one subspecies), Harmonia (one species), Hippodamia (two species), Mimoscymnus (two species), Psyllobora (one species), and Stenadalia (four species). In total, 184 location records are listed, of which 119 were from between 3000 and 4000 m, 57 between 4000 and 4900 m and eight above 4900 m, with the highest altitude record at 5250 m for Eriopis minima Hofmann. All records above 4000 m were obtained in the Puna biogeographic province within the Paramo Puneña biogeographic subregion. These records are the highest altitudes observed for the American continent and by far surpass others known for coccinellids worldwide. Several species of coccinellids living in sympatry at these high altitudes were verified, and in some cases, in situ development was inferred by the presence of immature stages. These findings are important to foresee the future effects of global warming that will affect especially the biological communities of extreme altitudes.

Actigraphy of Wrist and Ankle for Measuring Sleep Duration in Altitude Travelers.

Latshang, Tsogyal Daniela, Daniela Juliana Mueller, Christian Maurizio Lo Cascio, Anne-Christin Stöwhas, Katrin Stadelmann, Noemi Tesler, Peter Achermann, Reto Huber, Malcolm Kohler, and Konrad Ernst Bloch. Actigraphy of wrist and ankle for measuring sleep duration in altitude travelers. High Alt Med Biol. 17:194-202, 2016-Aims: Actigraphy might be convenient to assess sleep disturbances in altitude field studies. Therefore, we evaluated whether actigraphy accurately measures sleep duration in healthy subjects traveling to altitude. METHODS: Fifty-one healthy men, aged mean ± standard deviation (SD) 27 ± 9 years, were studied during one night at Zurich (490 m), two nights at Davos Wolfgang (1630 m), and two nights at Jakobshorn (2590 m), in randomized order. Sleep duration measured by actigraphy, using a one-axis device at the wrist (n = 51), a three-axis device at the other wrist, and a three-axis device at the ankle (n = 22), was compared with corresponding total sleep time (TST) measured by polysomnography. RESULTS: During 255 polysomnographic overnight studies, 449 paired actigraphic recordings were obtained. The median polysomnographic-derived TST ranged from 397 to 408 minutes. Actigraphic mean TST from wrists with one-axis and three-axis devices, and from ankle agreed well with polysomnographic values with a bias of +1, -7, +6 minutes, respectively. Corresponding limits of agreement (±2 SD of bias) were ±51, ±60, and ±59 minutes. Limits of agreement of mean TST over five nights by actigraphy and polysomnography were similar to the coefficient of repeatability (2 SD of mean) of polysomnographic TST, that is, ±31, ±38, and ±36 minutes versus ±34 minutes. CONCLUSIONS: Actigraphy of the wrist or ankle by a one-axis or a three-axis device accurately estimates mean TST in groups of subjects and mean TST over several nights in individuals traveling to altitude. Therefore, actigraphy is valuable for assessing effects of altitude and other environmental influences on sleep duration during field studies over extended periods.

The effect of hypoxia on intra-ocular, mean arterial, retinal venous and ocular perfusion pressures.

INTRODUCTION: High altitude hypoxia is linked to decreased blood oxygen saturation with a related increase of Endothelin-1 (ET-1) blood plasma levels. As a consequence of such elevated ET-1 levels, alterations of retinal venous and ocular perfusion pressures are suspected. PURPOSE: To measure the effect of hypoxia on intra-ocular pressure, mean arterial pressure, retinal venous pressure and to calculate ocular perfusion pressure. METHOD: An experimental, prospective cohort study with 33 healthy subjects was conducted in which the subjects were confronted with long-term (days) environmental hypoxia at high altitudes. Mean arterial pressure, arterial blood oxygen saturation, intra-ocular pressure, retinal venous and ocular perfusion pressure were measured at 300 m/1'000 ft (baseline), 4200 m/13'800 ft and 6000 m/19'700 ft above sea level. RESULTS: Arterial oxygen saturation (-13.06% ± 4.69, p = < 0.001; -23.46% ± 5.7,p = < 0.001), retinal venous pressure (+7.16 m Hg±8.2, p = < 0.001;+9.9 mm Hg±8.5, p = < 0.001) and ocular perfusion pressure (-8.49 mm Hg±10.6, p = < 0.001; -6.02 mm hg±11.2, p = 0.006) changed significantly from baseline at both high altitude of 4200 and 6000 m. Intra-ocular pressure did not change significantly at all altitudes (+1.16 mm Hg±4.5, p = 0.227; +0.84 mm Hg±4.8, p = 0.286) and mean arterial pressure changed significantly only at an altitude of 6000 m (+3,8 mm Hg±21.1, p = 0.005) from baseline. CONCLUSION: As hypoxia increases with higher altitude, arterial oxygen saturation and ocular perfusion pressure decreased, retinal venous pressure increased, intra-ocular pressure remains stable and mean arterial pressure was elevated only at 6000 m.