Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
14,045
result(s) for
"high altitude"
Sort by:
Black sun : a novel
\"A chilling and cinematic thriller set in 1961 in one of the most secretive locations in Soviet history. Ten days before the test of largest nuclear device in history--the Tsar Bomba--a KGB officer must investigate the murder of one of the architects of the bomb, and unravel a conspiracy that could set the world on fire\"-- Provided by publisher.
Book
The history and evolution of the Denisovan-EPAS1 haplotype in Tibetans
Recent studies suggest that admixture with archaic hominins played an important role in facilitating biological adaptations to new environments. For example, interbreeding with Denisovans facilitated the adaptation to high-altitude environments on the Tibetan Plateau. Specifically, the EPAS1 gene, a transcription factor that regulates the response to hypoxia, exhibits strong signatures of both positive selection and introgression from Denisovans in Tibetan individuals. Interestingly, despite being geographically closer to the Denisova Cave, East Asian populations do not harbor as much Denisovan ancestry as populations from Melanesia. Recently, two studies have suggested two independent waves of Denisovan admixture into East Asians, one of which is shared with South Asians and Oceanians. Here, we leverage data from EPAS1 in 78 Tibetan individuals to interrogate which of these two introgression events introduced the EPAS1 beneficial sequence into the ancestral population of Tibetans, and we use the distribution of introgressed segment lengths at this locus to infer the timing of the introgression and selection event. We find that the introgression event unique to East Asians most likely introduced the beneficial haplotype into the ancestral population of Tibetans around 48,700 (16,000–59,500) y ago, and selection started around 9,000 (2,500–42,000) y ago. Our estimates suggest that one of the most convincing examples of adaptive introgression is in fact selection acting on standing archaic variation.
Journal Article
Global and country-level estimates of human population at high altitude
Estimates of the global population of humans living at high altitude vary widely, and such data at the country level are unavailable. Herein, we use a geographic information system (GIS)-based approach to quantify human population at 500-m elevation intervals for each country. Based on georeferenced data for population (LandScan Global 2019) and elevation (Global Multiresolution Terrain Elevation Data), 500.3 million humans live at ≥1,500 m, 81.6 million at ≥2,500 m, and 14.4 million at ≥3,500 m. Ethiopia has the largest absolute population at ≥1,500 m and ≥2,500 m, while China has the greatest at ≥3,500 m. Lesotho has the greatest percentage of its population above 1,500 m, while Bolivia has the greatest at ≥2,500 m and ≥3,500 m. High altitude presents a myriad of environmental stresses that provoke physiological responses and adaptation, and consequently impact disease prevalence and severity. While the majority of high-altitude physiology research is based upon lowlanders from western, educated, industrialized, rich, and democratic countries ascending to high altitude, the global population distribution of high-altitude residents encourages an increased emphasis on understanding high-altitude physiology, adaptation, epidemiology, and public health in the ∼500 million permanent high-altitude residents.
Journal Article
Comparative transcriptomics of 3 high-altitude passerine birds and their low-altitude relatives
High-altitude environments present strong stresses for living organisms, which have driven striking phenotypic and genetic adaptations. While previous studies have revealed multiple genetic adaptations in high-altitude species, how evolutionary history (i.e., phylogenetic background) contributes to similarity in genetic adaptations to high-altitude environments is largely unknown, in particular in a group of birds. We explored this in 3 high-altitude passerine birds from the Qinghai-Tibet Plateau and their low-altitude relatives in lowland eastern China. We generated transcriptomic data for 5 tissues across these species and compared sequence changes and expression shifts between high- and low-altitude pairs. Sequence comparison revealed that similarity in all 3 high-altitude species was high for genes under positive selection (218 genes) but low in amino acid substitutions (only 4 genes sharing identical amino acid substitutions). Expression profiles for all genes identified a tissue-specific expression pattern (i.e., all species clustered by tissue). By contrast, an altitude-related pattern was observed in genes differentially expressed between all 3 species pairs and genes associated with altitude, suggesting that the high-altitude environment may drive similar expression shifts in the 3 high-altitude species. Gene expression level, gene connectivity, and the interactions of these 2 factors with altitude were correlated with evolutionary rates. Our results provide evidence for how gene sequence changes and expression shifts work in a concerted way in a group of high-altitude birds, leading to similar evolution routes in response to high-altitude environmental stresses.
Journal Article
A late Middle Pleistocene Denisovan mandible from the Tibetan Plateau
Denisovans are members of a hominin group who are currently only known directly from fragmentary fossils, the genomes of which have been studied from a single site, Denisova Cave
1
–
3
in Siberia. They are also known indirectly from their genetic legacy through gene flow into several low-altitude East Asian populations
4
,
5
and high-altitude modern Tibetans
6
. The lack of morphologically informative Denisovan fossils hinders our ability to connect geographically and temporally dispersed fossil hominins from Asia and to understand in a coherent manner their relation to recent Asian populations. This includes understanding the genetic adaptation of humans to the high-altitude Tibetan Plateau
7
,
8
, which was inherited from the Denisovans. Here we report a Denisovan mandible, identified by ancient protein analysis
9
,
10
, found on the Tibetan Plateau in Baishiya Karst Cave, Xiahe, Gansu, China. We determine the mandible to be at least 160 thousand years old through U-series dating of an adhering carbonate matrix. The Xiahe specimen provides direct evidence of the Denisovans outside the Altai Mountains and its analysis unique insights into Denisovan mandibular and dental morphology. Our results indicate that archaic hominins occupied the Tibetan Plateau in the Middle Pleistocene epoch and successfully adapted to high-altitude hypoxic environments long before the regional arrival of modern
Homo sapiens
.
Fossil evidence indicates that Denisovans occupied the Tibetan Plateau in the Middle Pleistocene epoch and successfully adapted to this high-altitude hypoxic environments long before the regional arrival of modern
Homo sapiens
.
Journal Article
Curcumin-mediated enhancement of lung barrier function in rats with high-altitude-associated acute lung injury via inhibition of inflammatory response
Background
Exposure to a hypobaric hypoxic environment at high altitudes can lead to lung injury. In this study, we aimed to determine whether curcumin (Cur) could improve lung barrier function and protect against high-altitude-associated acute lung injury.
Methods
Two hundred healthy rats were randomly divided into standard control, high-altitude control (HC), salidroside (40 mg/kg, positive control), and Cur (200 mg/kg) groups. Each group was further divided into five subgroups. Basic vital signs, lung injury histopathology, routine blood parameters, plasma lactate level, and arterial blood gas indicators were evaluated. Protein and inflammatory factor (tumor necrosis factor α (TNF-α), interleukin [IL]-1β, IL-6, and IL-10) concentrations in bronchoalveolar lavage fluid (BALF) were determined using the bicinchoninic acid method and enzyme-linked immunosorbent assay, respectively. Inflammation-related and lung barrier function-related proteins were analyzed using immunoblotting.
Results
Cur improved blood routine indicators such as hemoglobin and hematocrit and reduced the BALF protein content and TNF-α, IL-1β, and IL-6 levels compared with those in the HC group. It increased IL-10 levels and reduced pulmonary capillary congestion, alveolar hemorrhage, and the degree of pulmonary interstitial edema. It increased oxygen partial pressure, oxygen saturation, carbonic acid hydrogen radical, and base excess levels, and the expression of zonula occludens 1, occludin, claudin-4, and reduced carbon dioxide partial pressure, plasma lactic acid, and the expression of phospho-nuclear factor kappa.
Conclusions
Exposure to a high-altitude environment for 48 h resulted in severe lung injury in rats. Cur improved lung barrier function and alleviated acute lung injury in rats at high altitudes.
Highlights
•
Curcumin (Cur) improves lung barrier function under high-altitude stress in rats
•
Cur mitigated acute lung injury under high-altitude stress
•
Cur improved hemoglobin and hematocrit levels under high-altitude stress
•
Cur reduced bronchoalveolar lavage fluid protein content under high-altitude stress
•
Cur reduced inflammatory factor TNF-α, IL-α, IL-6 levels under high-altitude stress
Graphical Abstract
Journal Article
Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth
The unexpectedly high flux of cosmic-ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report the detection, using the High-Altitude Water Cherenkov Observatory (HAWC), of extended tera–electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of accelerated leptons, but the measured tera–electron volt emission profile constrains the diffusion of particles away from these sources to be much slower than previously assumed. We demonstrate that the leptons emitted by these objects are therefore unlikely to be the origin of the excess positrons, which may have a more exotic origin.
Journal Article
The earliest human occupation of the high-altitude Tibetan Plateau 40 thousand to 30 thousand years ago
Human colonization of the high-altitude Tibetan Plateau has generally been thought to have been confined to the past few thousand years of the Holocene. Zhang et al. report an investigation of the Nwya Devu archaeological site in central Tibet, 4600 meters above sea level, with Paleolithic occupation dates of ∼40 thousand to 30 thousand years ago (see the Perspective by Zhang and Dennell). The site has yielded a range of stone tools, indicating the adaptive ability of early modern humans to the harsh environment of the “roof of the world.” The findings also suggest that people from Tibet and Siberia may have interacted at this time. Science , this issue p. 1049 ; see also p. 992 The Nwya Devu Paleolithic site in Tibet, 4600 meters above sea level, preserves evidence of early human high-altitude adaptation. The Tibetan Plateau is the highest and one of the most demanding environments ever inhabited by humans. We investigated the timing and mechanisms of its initial colonization at the Nwya Devu site, located nearly 4600 meters above sea level. This site, dating from 40,000 to 30,000 years ago, is the highest Paleolithic archaeological site yet identified globally. Nwya Devu has yielded an abundant blade tool assemblage, indicating hitherto-unknown capacities for the survival of modern humans who camped in this environment. This site deepens the history of the peopling of the “roof of the world” and the antiquity of human high-altitude occupations more generally.
Journal Article
Extracellular enzyme stoichiometry reveals the carbon and phosphorus limitations of microbial metabolisms in the rhizosphere and bulk soils in alpine ecosystems
Aims
Alpine ecosystems are important terrestrial carbon (C) pools, and microbial decomposers play a key role in cycling soil C. Microbial metabolic limitations in these ecosystems, however, have rarely been studied. The objectives of this study are to reveal the characteristics of microbial nutrient limitation, and decipher the drivers in the alpine ecosystems.
Methods
Models of extracellular enzymatic stoichiometry were applied to examine and compare the metabolic limitations of the microbial communities in bulk and rhizosphere soils along an altitudinal gradient (2800–3500 m a.s.l.) under the same type of vegetation (
Abies fabri
) on Gongga Mountain, eastern Tibetan Plateau.
Results
The soil microbial communities suffered from relative C and phosphorus (P) limitations in the alpine ecosystem despite of high soil nutrient contents here. Partial least squares path modelling (PLS-PM) revealed that the limitations were directly regulated by soil nutrient stoichiometry, followed by nutrient availability. The C and P limitations were higher at the high altitudes (3000–3500 m) than that at the low altitude (2800 m), which mainly attribute to changes of soil temperature and moisture along the altitudinal gradient. This suggested that global warming may relieve microbial metabolic limitation in the alpine ecosystems, and then is conducive to the retention of organic C in soil. Furthermore, the C and P limitations varied significantly between the bulk and rhizosphere soils at the high altitudes (3200–3500 m), but not at the low altitudes. This indicated the influences of vegetation on the microbial metabolisms, while the influences could decrease under the scenario of global warming.
Conclusions
Our study suggests that the alpine ecosystems with high organic C storage harbour abundant microbial populations limited by relative C and P, which have sensitive metabolic characteristics. This could thus potentially lead to large fluctuations in the soil C turnover under climate change. The study provides important insights linking microbial metabolisms to the environmental gradients, and improves our understanding of C cycling in alpine ecosystems.
Journal Article
Pulmonary Hypertension in Acute and Chronic High Altitude Maladaptation Disorders
Alveolar hypoxia is the most prominent feature of high altitude environment with well-known consequences for the cardio-pulmonary system, including development of pulmonary hypertension. Pulmonary hypertension due to an exaggerated hypoxic pulmonary vasoconstriction contributes to high altitude pulmonary edema (HAPE), a life-threatening disorder, occurring at high altitudes in non-acclimatized healthy individuals. Despite a strong physiologic rationale for using vasodilators for prevention and treatment of HAPE, no systematic studies of their efficacy have been conducted to date. Calcium-channel blockers are currently recommended for drug prophylaxis in high-risk individuals with a clear history of recurrent HAPE based on the extensive clinical experience with nifedipine in HAPE prevention in susceptible individuals. Chronic exposure to hypoxia induces pulmonary vascular remodeling and development of pulmonary hypertension, which places an increased pressure load on the right ventricle leading to right heart failure. Further, pulmonary hypertension along with excessive erythrocytosis may complicate chronic mountain sickness, another high altitude maladaptation disorder. Importantly, other causes than hypoxia may potentially underlie and/or contribute to pulmonary hypertension at high altitude, such as chronic heart and lung diseases, thrombotic or embolic diseases. Extensive clinical experience with drugs in patients with pulmonary arterial hypertension suggests their potential for treatment of high altitude pulmonary hypertension. Small studies have demonstrated their efficacy in reducing pulmonary artery pressure in high altitude residents. However, no drugs have been approved to date for the therapy of chronic high altitude pulmonary hypertension. This work provides a literature review on the role of pulmonary hypertension in the pathogenesis of acute and chronic high altitude maladaptation disorders and summarizes current knowledge regarding potential treatment options.
Journal Article