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International Journal of Biometeorology Apr 1997The study was conducted on human volunteers as controls as well as after administration of vanadyl sulphate on induction to high altitude (HA) at 3500 m. The plasma... (Clinical Trial)
Clinical Trial
The study was conducted on human volunteers as controls as well as after administration of vanadyl sulphate on induction to high altitude (HA) at 3500 m. The plasma vanadium contents were significantly reduced in the control group on abrupt induction to HA on days 3 and 10, indicating redistribution to other organs/tissues under the stressful situation. In the vanadium salt-treated group, plasma vanadium contents were similar to those obtained at sea-level. Administration of vanadyl sulphate did not act as a diuretic. Moreover the vanadium supplemented group drank more water and also excrete less urine than the control group.
Topics: Acclimatization; Altitude; Blood; Blood Viscosity; Diuresis; Drinking; Humans; Vanadium
PubMed: 9140210
DOI: 10.1007/s004840050025 -
International Journal of Sports Medicine Oct 1992Anaerobic metabolism is usually evaluated by the determination of the anaerobic capacity and the maximal anaerobic mechanical external power (Wmax). Conflicting results... (Review)
Review
Anaerobic metabolism is usually evaluated by the determination of the anaerobic capacity and the maximal anaerobic mechanical external power (Wmax). Conflicting results are reported on anaerobic capacity evaluated by maximal oxygen deficit and debt, and maximal blood lactate concentration during acute or chronic hypoxia (acclimatized subjects). Data on muscle biopsies (lactate concentration, changes in ATP, phosphocreatine and glycogen stores, glycolytic enzyme activities) and the few studies on lactate flux give in most cases evidence of a non-alteration of the anaerobic capacity for altitudes up to 5,500 m. No differences are observed in Wmax measured at high altitudes up to 5,200 m during intense short-term exercises: (1) jumps on a force platform which is a good indicator of alactic Wmax, and (2) 7-10 s sprints (i.e. force-velocity test) which solicit alactic metabolism but also lactic pathway. For exercises of duration equal or more than 30 s (i.e. Wingate test), there are conflicting results because a lower participation of aerobic metabolism during this test at high altitude can interfere with anaerobic performance. In conclusion, we can admit that anaerobic performances are not altered by high altitudes up to 5,200 m if the length of exposure does not exceed 5 weeks. After this period, muscle mass begins to decrease.
Topics: Acclimatization; Altitude; Energy Metabolism; Exercise; Humans; Hypoxia; Lactates; Lactic Acid; Muscles; Physical Endurance; Time Factors
PubMed: 1483803
DOI: 10.1055/s-2007-1024604 -
Maroc Medical Oct 1954
Topics: Acclimatization; Animals; Cattle
PubMed: 13264739
DOI: No ID Found -
Scientific Reports Apr 2024Local adaptation can increase fitness under stable environmental conditions. However, in rapidly changing environments, compensatory mechanisms enabled through...
Local adaptation can increase fitness under stable environmental conditions. However, in rapidly changing environments, compensatory mechanisms enabled through plasticity may better promote fitness. Climate change is causing devastating impacts on coral reefs globally and understanding the potential for adaptive and plastic responses is critical for reef management. We conducted a four-year, three-way reciprocal transplant of the Caribbean coral Siderastrea siderea across forereef, backreef, and nearshore populations in Belize to investigate the potential for environmental specialization versus plasticity in this species. Corals maintained high survival within forereef and backreef environments, but transplantation to nearshore environments resulted in high mortality, suggesting that nearshore environments present strong environmental selection. Only forereef-sourced corals demonstrated evidence of environmental specialization, exhibiting the highest growth in the forereef. Gene expression profiling 3.5 years post-transplantation revealed that transplanted coral hosts exhibited profiles more similar to other corals in the same reef environment, regardless of their source location, suggesting that transcriptome plasticity facilitates acclimatization to environmental change in S. siderea. In contrast, algal symbiont (Cladocopium goreaui) gene expression showcased functional variation between source locations that was maintained post-transplantation. Our findings suggest limited acclimatory capacity of some S. siderea populations under strong environmental selection and highlight the potential limits of coral physiological plasticity in reef restoration.
Topics: Animals; Anthozoa; Coral Reefs; Caribbean Region; Transcriptome; Acclimatization
PubMed: 38570591
DOI: 10.1038/s41598-024-57319-0 -
Chest Apr 2022
Topics: Acclimatization; Altitude; Altitude Sickness; Humans; Hypoxia; Iron; Vasoconstriction
PubMed: 35396045
DOI: 10.1016/j.chest.2021.10.009 -
Plant Science : An International... Jan 2011Temperature is one of the most important environmental factors limiting the geographical distribution of plants and accounts for significant reductions in the yield of... (Review)
Review
Temperature is one of the most important environmental factors limiting the geographical distribution of plants and accounts for significant reductions in the yield of agriculturally important crops. Low temperature damages many plant species, especially those adapted to tropical climates. In contrast, some species from temperate regions are able to develop freezing tolerance in response to low-non-freezing temperature, an adaptive process named cold acclimation. Numerous molecular, biochemical and physiological changes occur during cold acclimation, most of them being associated with significant changes in gene expression and metabolite profiles. During recent years, transcriptomic and metabolomic approaches have allowed the identification of cold-responsive genes and main metabolites which accumulate in plants exposed to cold. The obtained data support the previously held idea that polyamines (PAs) are involved in plant responses to cold, although their specific role is still not well understood. In this review, we synthesize published data regarding PA-responses to cold stress and integrate them with global transcriptional and metabolic changes. The potential of PA genetic engineering for the development of plants resistant to cold and freezing temperatures, and their plausible mechanisms of action are also discussed.
Topics: Acclimatization; Arabidopsis; Cold Temperature; Gene Expression Regulation, Plant; Models, Biological; Polyamines
PubMed: 21421344
DOI: 10.1016/j.plantsci.2010.07.022 -
Aviation, Space, and Environmental... Aug 1991Peripheral acclimatization to cold in scuba divers stationed at the British Antarctic Survey's Signy Station was investigated during a year in Antarctica. Five divers...
Peripheral acclimatization to cold in scuba divers stationed at the British Antarctic Survey's Signy Station was investigated during a year in Antarctica. Five divers and five non-diver controls underwent monthly laboratory tests of index finger immersion in cold water for 30 min. Index finger pulp temperature and time of onset of cold-induced vasodilatation (CIVD) were measured. Pain was recorded with verbal and numerical psychophysical subjective pain ratings. Average finger temperatures and median finger pain from 6-30 min of immersion, maximum finger temperatures during the first CIVD cycle, and finger temperatures at the onset of CIVD were calculated. Comparison of the variables recorded from divers and non-divers were performed with analysis of variance. No significant differences were found among the variables recorded from divers and non-divers. From a review of the literature, divers have responses typical of non-cold-adapted Caucasians. There is, therefore, no evidence that Signy divers peripherally acclimatized to cold. We suggest that these findings occur because either the whole body cooling which divers undergo inhibits peripheral acclimatization or because of insufficiently frequent or severe cold exposure while diving. Further basic studies on the duration, frequency and severity of cold exposure necessary to induce peripheral cold acclimatization are required before this question can be satisfactorily answered.
Topics: Acclimatization; Adult; Analysis of Variance; Antarctic Regions; Cold Climate; Diving; Fingers; Humans; Male; Skin Temperature; Vasodilation
PubMed: 1930054
DOI: No ID Found -
General and Comparative Endocrinology May 2020Biological activities in ectothermic vertebrates depend to a great extent on ambient temperature. Adapting their biological systems to annual or short-term alterations...
Biological activities in ectothermic vertebrates depend to a great extent on ambient temperature. Adapting their biological systems to annual or short-term alterations in temperature may play an important role in thermal resistance or overwintering survival. Using SDS-PAGE and western blot, we examined plasma proteins in bullfrog (Rana catesbeiana) tadpoles that were seasonally acclimatized (winter vs. summer) or thermally acclimated (4 °C vs. 21 °C) and identified two season-responsive proteins. The first, transthyretin (TTR), is a plasma thyroid hormone distributor protein that was abundant in summer, and the second is a protein containing C-type lectin-like domain (CTLD) that was abundant in winter and cold acclimation of 4 weeks. Sequence analysis revealed that the C-terminal carbohydrate recognition domain of this CTLD protein (termed collectin X) was highly similar to those of the collectin family members, which participate in complement activation of the innate immune system; however, it lacked most of collagen-like domain. Among the hepatic genes involved in the thyroid system, ttr and dio3 were up-regulated, whereas thra and thrb were down-regulated, in summer acclimatization or warm acclimation. In contrast, the collectin X gene (colectx), as well as colect10 and colect11 in the collectin family involved in the innate immune system, were down-regulated during warm acclimation, although fcn2 in the ficolin family was up-regulated during summer acclimatization and warm acclimation. These findings indicate that seasonal acclimatization and thermal acclimation differentially affect some components of the thyroid and innate immune systems at protein and transcript levels.
Topics: Acclimatization; Animals; Blood Proteins; Larva; Rana catesbeiana; Seasons; Temperature
PubMed: 31987871
DOI: 10.1016/j.ygcen.2020.113396 -
Experimental Physiology May 2014Cerebral hypoxaemia associated with rapid ascent to high altitude can be life threatening; yet, with proper acclimatization, cerebral function can be maintained well...
Cerebral hypoxaemia associated with rapid ascent to high altitude can be life threatening; yet, with proper acclimatization, cerebral function can be maintained well enough for humans to thrive. We investigated adjustments in global and regional cerebral oxygen delivery (DO2) as 21 healthy volunteers rapidly ascended and acclimatized to 5260 m. Ultrasound indices of cerebral blood flow in internal carotid and vertebral arteries were measured at sea level, upon arrival at 5260 m (ALT1; atmospheric pressure 409 mmHg) and after 16 days of acclimatization (ALT16). Cerebral DO2 was calculated as the product of arterial oxygen content and flow in each respective artery and summed to estimate global cerebral blood flow. Vascular resistances were calculated as the quotient of mean arterial pressure and respective flows. Global cerebral blood flow increased by ∼70% upon arrival at ALT1 (P < 0.001) and returned to sea-level values at ALT16 as a result of changes in cerebral vascular resistance. A reciprocal pattern in arterial oxygen content maintained global cerebral DO2 throughout acclimatization, although DO2 to the posterior cerebral circulation was increased by ∼25% at ALT1 (P = 0.032). We conclude that cerebral DO2 is well maintained upon acute exposure and acclimatization to hypoxia, particularly in the posterior and inferior regions of the brain associated with vital homeostatic functions. This tight regulation of cerebral DO2 was achieved through integrated adjustments in local vascular resistances to alter cerebral perfusion during both acute and chronic exposure to hypoxia.
Topics: Acclimatization; Altitude; Cerebrovascular Circulation; Female; Humans; Male; Middle Cerebral Artery; Oxygen; Regional Blood Flow; Young Adult
PubMed: 24243839
DOI: 10.1113/expphysiol.2013.075184 -
The Journal of Experimental Biology Oct 1982Hyperventilation is one of the most important features of acclimatization to high altitude. Resting ventilation at extreme altitudes increases up to fourfold and... (Review)
Review
Hyperventilation is one of the most important features of acclimatization to high altitude. Resting ventilation at extreme altitudes increases up to fourfold and exercise ventilation for a given work level increases to the same extent. Hypoxic stimulation of the peripheral chemoreceptors is the chief mechanism for the hyperventilation but there is also evidence that central sensitization of the respiratory centres occurs. Permanent residents of high altitude have a blunted hypoxic ventilatory response compared to acclimatized lowlanders. Cardiac output increases in responses to acute hypoxia but returns to normal in acclimatized lowlanders. Oxygen uptake at extreme altitudes is markedly limited by the diffusion properties of the blood gas barrier. As a consequence the maximal oxygen consumption of a climber near the summit of Mount Everest is near his basal oxygen requirements. Maximal oxygen consumption is so sensitive to barometric pressure that it may be that day-to-day variations will affect the chances of a climber reaching the summit without supplementary oxygen.
Topics: Acclimatization; Altitude; Blood Circulation; Heart; Humans; Physical Exertion; Respiration; Rest; Work Capacity Evaluation
PubMed: 6757367
DOI: 10.1242/jeb.100.1.147