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Journal of Physiological Anthropology Apr 2020While active heat acclimation strategies have been robustly explored, not many studies highlighted passive heat acclimation strategies. Particularly, little evidence...
BACKGROUND
While active heat acclimation strategies have been robustly explored, not many studies highlighted passive heat acclimation strategies. Particularly, little evidence demonstrated advantages of utilizing a water-perfused suit as a passive heating strategy. This study aimed to explore heat adaptive changes in physiological and perceptual responses during 10-day heat acclimation training using a water-perfused suit.
METHODS
Nineteen young males were divided into three experimental groups: exercise condition (N = 6, HA, 1-h exercise at 6 km h followed by 1-h rest in a sitting position), exercise and passive heating condition (N = 6, HA, 1-h exercise at 6 km h followed 1-h passive heating in a sitting position), and passive heating condition (N = 7, HA, 2-h passive heating in a sitting position). All heating programs were conducted for 10 consecutive days in a climatic chamber maintained at 33 °C with 60% relative humidity. The passive heating was conducted using a newly developed water-perfused suit with 44 °C water.
RESULTS
Greater whole-body sweat rate and alleviated perceptual strain were found in HA and HA after 5 and/or 10 days (P < 0.05) but not in the exercise-only condition (HA). Lower rectal temperature and heart rate were found in all conditions after the training (P < 0.05). Heat adaptive changes appeared earlier in HA except for sweat responses.
CONCLUSIONS
For heat acclimation in hot humid environments, passive and post-exercise heat acclimation training using the suit (water inflow temperature 44 °C) were more effective than the mild exercise (1-h walking at 6 km h). This form of passive heating (HA) may be an especially effective strategy for the elderly and the disabled who are not able to exercise in hot environments.
Topics: Acclimatization; Adult; Body Temperature Regulation; Exercise; Hot Temperature; Humans; Male; Perception; Republic of Korea; Sweating; Water; Young Adult
PubMed: 32290869
DOI: 10.1186/s40101-020-00217-x -
Sports Medicine (Auckland, N.Z.) Nov 2016Exercise training (ExT) prompts multiple beneficial adaptations associated with vascular health, such as increases in skeletal muscle capillarization and vascular... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Exercise training (ExT) prompts multiple beneficial adaptations associated with vascular health, such as increases in skeletal muscle capillarization and vascular dilator function and decreases in arterial stiffness. However, whether ExT performed in hypoxic conditions induces enhanced effects is unclear.
OBJECTIVE
We sought to systematically review the literature and determine whether hypoxic ExT leads to superior vascular adaptations compared with normoxic ExT.
METHODS
We searched MEDLINE, Scopus, and Web of Science from their inception until September 2015 for articles assessing vascular adaptations to ExT performed under hypoxic and normoxic conditions. We performed meta-analyses to determine the standardized mean difference (SMD) between the effects of ExT performed in hypoxia versus normoxia on vascular adaptations. We assessed heterogeneity among studies using I statistics and evaluated publication bias via the Begg and Mazumdar's rank correlation test and Egger's regression test.
RESULTS
After systematic review, we included 21 controlled studies, including a total of 331 individuals (mean age 19-57 years, 265 males). ExT programs primarily consisted of cycling endurance training performed in normobaric hypoxia or normoxia; duration ranged from 3 to 10 weeks. The exercise intensity was similar in relative terms in the groups trained in hypoxia and normoxia in the majority of studies (17 of 21). After data pooling, skeletal muscle capillarization (n = 182, SMD = 0.40, 95 % confidence interval [CI] 0.10-0.70; P = 0.01) and vascular dilator function (n = 71, SMD = 0.67, 95 % CI 0.17-1.18; P = 0.009) but not arterial stiffness (n = 112, SMD = -0.03, 95 % CI -0.69 to 0.63; P = 0.93), were enhanced with ExT performed in hypoxia versus normoxia. We only found heterogeneity among studies assessing arterial stiffness (I = 63 %, P = 0.02), and no publication bias was detected.
CONCLUSION
Based on current published studies, hypoxic ExT potentiates vascular adaptations related to skeletal muscle capillarization and dilator function. These findings may contribute to establishing effective exercise programs designed to enhance vascular health.
Topics: Acclimatization; Adult; Exercise; Humans; Hypoxia; Male; Middle Aged; Muscle, Skeletal; Oxygen Consumption; Vascular Stiffness; Young Adult
PubMed: 27286988
DOI: 10.1007/s40279-016-0570-5 -
Journal of Comparative Physiology. B,... Oct 2005Biological functions are dependent on the temperature of the organism. Animals may respond to fluctuation in the thermal environment by regulating their body temperature... (Review)
Review
Biological functions are dependent on the temperature of the organism. Animals may respond to fluctuation in the thermal environment by regulating their body temperature and by modifying physiological and biochemical rates. Phenotypic flexibility (reversible phenotypic plasticity, acclimation, or acclimatisation in rate functions occurs in all major taxonomic groups and may be considered as an ancestral condition. Within the Reptilia, representatives from all major groups show phenotypic flexibility in response to long-term or chronic changes in the thermal environment. Acclimation or acclimatisation in reptiles are most commonly assessed by measuring whole animal responses such as oxygen consumption, but whole animal responses are comprised of variation in individual traits such as enzyme activities, hormone expression, and cardiovascular functions. The challenge now lies in connecting the changes in the components to the functioning of the whole animal and its fitness. Experimental designs in research on reptilian thermal physiology should incorporate the capacity for reversible phenotypic plasticity as a null-hypothesis, because the significance of differential body temperature-performance relationships (thermal reaction norms) between individuals, populations, or species cannot be assessed without testing that null-hypothesis.
Topics: Acclimatization; Animals; Body Temperature Regulation; Marine Biology; Models, Biological; Oxygen Consumption; Phenotype; Reptiles
PubMed: 16034580
DOI: 10.1007/s00360-005-0010-6 -
International Journal of Sports Medicine Jun 1998More is known about the time course for the acquisition of human heat acclimation during exercise than its decay or loss. Pioneering research in the 1940s led to our... (Comparative Study)
Comparative Study Review
More is known about the time course for the acquisition of human heat acclimation during exercise than its decay or loss. Pioneering research in the 1940s led to our early understanding of the heat acclimation process and its subsequent decay with further knowledge concerning the associated physiological mechanisms in later years. For both hot-dry and hot-humid environments, nearly complete exercise-heat acclimation occurs after 7 to 10 days of exposure. However, about two-thirds to 75% of the physiological adjustments and improvements in performance are seen in 4 to 6 days. Individuals with high levels of aerobic fitness are partially but not fully acclimated to the heat. Most of the early studies on decay or loss of heat acclimation are flawed by very small samples, incomplete heat acclimation or inappropriate measurements. Nevertheless, these studies are pioneering in a sense because they indicate that the retention of heat acclimation is quite variable between individuals and environments. Retention of the benefits of heat acclimation appears to remain longer for dry compared to humid heat. High levels of aerobic fitness seem associated with greater retention of heat acclimation. Further well-designed and definitive studies on decay or loss of heat acclimation appear necessary.
Topics: Acclimatization; Body Temperature Regulation; Environment; Environmental Exposure; Exercise; Heart Rate; Hot Temperature; Humans; Humidity; Oxygen Consumption; Physical Endurance; Physical Fitness; Time Factors
PubMed: 9694426
DOI: 10.1055/s-2007-971985 -
Nature Plants Apr 2020Predicting the consequences of manipulating genotype (G) and agronomic management (M) on agricultural ecosystem performances under future environmental (E) conditions... (Review)
Review
Predicting the consequences of manipulating genotype (G) and agronomic management (M) on agricultural ecosystem performances under future environmental (E) conditions remains a challenge. Crop modelling has the potential to enable society to assess the efficacy of G × M technologies to mitigate and adapt crop production systems to climate change. Despite recent achievements, dedicated research to develop and improve modelling capabilities from gene to global scales is needed to provide guidance on designing G × M adaptation strategies with full consideration of their impacts on both crop productivity and ecosystem sustainability under varying climatic conditions. Opportunities to advance the multiscale crop modelling framework include representing crop genetic traits, interfacing crop models with large-scale models, improving the representation of physiological responses to climate change and management practices, closing data gaps and harnessing multisource data to improve model predictability and enable identification of emergent relationships. A fundamental challenge in multiscale prediction is the balance between process details required to assess the intervention and predictability of the system at the scales feasible to measure the impact. An advanced multiscale crop modelling framework will enable a gene-to-farm design of resilient and sustainable crop production systems under a changing climate at regional-to-global scales.
Topics: Acclimatization; Climate Change; Crops, Agricultural; Models, Biological
PubMed: 32296143
DOI: 10.1038/s41477-020-0625-3 -
International Journal of Environmental... Sep 2021Several aspects of cognition can be affected after cold exposure, but contradictory results have been reported regarding affected cognitive domains. The aim of the... (Review)
Review
Several aspects of cognition can be affected after cold exposure, but contradictory results have been reported regarding affected cognitive domains. The aim of the current systematic review was to evaluate the effects of specific cold exposure on cognitive performance in healthy subjects. A systematic search was performed using MEDLINE (through PubMed), EMBASE (Scopus) and PsycINFO databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Inclusion criteria were healthy subjects exposed to a cold environment (either simulated or not) and cognitive performance related to cold exposure with an experimental design. The literature search identified 18 studies, eight studies investigated the effect of cold air exposure and ten the effect of cold water immersion on cognitive performance of healthy subjects. There were several differences among the studies (environmental temperature reached, time of exposure, timing, and type of cognitive test administration). Cold exposure induced in most of the experimental settings (15 of 18) an impairment of CP even before accidental hypothermia was established. The most investigated and affected cognitive domains were attention and processing speed, executive function, and memory. Gender differences and effects of repeated exposure and possible acclimation on cognitive performance need further studies to be confirmed.
Topics: Acclimatization; Adult; Attention; Cognition; Cognitive Dysfunction; Executive Function; Humans
PubMed: 34574649
DOI: 10.3390/ijerph18189725 -
Frontiers in Bioscience (Landmark... Jan 2010Thermal comfort--the state of mind, which expresses satisfaction with the thermal environment--is an important aspect of the building design process as modern man spends... (Review)
Review
Thermal comfort--the state of mind, which expresses satisfaction with the thermal environment--is an important aspect of the building design process as modern man spends most of the day indoors. This paper reviews the developments in indoor thermal comfort research and practice since the second half of the 1990s, and groups these developments around two main themes; (i) thermal comfort models and standards, and (ii) advances in computerization. Within the first theme, the PMV-model (Predicted Mean Vote), created by Fanger in the late 1960s is discussed in the light of the emergence of models of adaptive thermal comfort. The adaptive models are based on adaptive opportunities of occupants and are related to options of personal control of the indoor climate and psychology and performance. Both models have been considered in the latest round of thermal comfort standard revisions. The second theme focuses on the ever increasing role played by computerization in thermal comfort research and practice, including sophisticated multi-segmental modeling and building performance simulation, transient thermal conditions and interactions, thermal manikins.
Topics: Acclimatization; Body Temperature; Body Temperature Regulation; Environment Design; Housing; Humans; Models, Biological; Research; Research Design; Temperature
PubMed: 20036845
DOI: 10.2741/3645 -
Nature Communications Apr 2023At the molecular level, the evolution of life is driven by the generation and diversification of adaptation mechanisms. A universal description of adaptation-capable...
At the molecular level, the evolution of life is driven by the generation and diversification of adaptation mechanisms. A universal description of adaptation-capable chemical reaction network (CRN) structures has remained elusive until now, since currently-known criteria for adaptation apply only to a tiny subset of possible CRNs. Here we identify the definitive structural requirements that characterize all adaptation-capable collections of interacting molecules, however large or complex. We show that these network structures implement a form of integral control in which multiple independent integrals can collaborate to confer the capacity for adaptation on specific molecules. Using an algebraic algorithm informed by these findings, we demonstrate the existence of embedded integrals in a variety of biologically important CRNs that have eluded previous methods, and for which adaptation has been observed experimentally. This definitive picture of biological adaptation at the level of intermolecular interactions represents a blueprint for adaptation-capable signaling networks across all domains of life, and for the design of synthetic biosystems.
Topics: Adaptation, Physiological; Acclimatization; Signal Transduction
PubMed: 37081018
DOI: 10.1038/s41467-023-38011-9 -
International Journal of Biological... Jan 2023Microbial lipases are very prominent biocatalysts because of their ability to catalyze a wide variety of reactions in aqueous and non-aqueous media. Here microbial... (Review)
Review
Microbial lipases are very prominent biocatalysts because of their ability to catalyze a wide variety of reactions in aqueous and non-aqueous media. Here microbial lipases from different origins (psychrophiles, mesophiles, and thermophiles) have been reviewed. This review emphasizes an update of structural diversity in temperature adaptation and industrial applications, of psychrophilic, mesophilic, and thermophilic lipases. The microbial origins of lipases are logically dynamic, proficient, and also have an extensive range of industrial uses with the manufacturing of altered molecules. It is therefore of interest to understand the molecular mechanisms of adaptation to temperature in occurring lipases. However, lipases from extremophiles (psychrophiles, and thermophiles) are widely used to design biotransformation reactions with higher yields, fewer byproducts, or useful side products and have been predicted to catalyze those reactions also, which otherwise are not possible with the mesophilic lipases. Lipases as a multipurpose biological catalyst have given a favorable vision in meeting the needs of several industries such as biodiesel, foods, and drinks, leather, textile, detergents, pharmaceuticals, and medicals.
Topics: Temperature; Lipase; Adaptation, Physiological; Acclimatization
PubMed: 36402388
DOI: 10.1016/j.ijbiomac.2022.11.146 -
PLoS Genetics Jun 2023Genetic robustness can be achieved via several mechanisms including transcriptional adaptation (TA), a sequence similarity-driven process whereby mutant mRNA degradation...
Genetic robustness can be achieved via several mechanisms including transcriptional adaptation (TA), a sequence similarity-driven process whereby mutant mRNA degradation products modulate, directly or indirectly, the expression of so-called adapting genes. To identify the sequences required for this process, we utilized a transgenic approach in Caenorhabditis elegans, combining an overexpression construct for a mutant gene (act-5) and a fluorescent reporter for the corresponding adapting gene (act-3). Analyzing a series of modifications for each construct, we identified, in the 5' regulatory region of the act-3 locus, a 25-base pair (bp) element which exhibits 60% identity with a sequence in the act-5 mRNA and which, in the context of a minimal promoter, is sufficient to induce ectopic expression of the fluorescent reporter. The 25 nucleotide (nt) element in the act-5 mRNA lies between the premature termination codon (PTC) and the next exon/exon junction, suggesting the importance of this region of the mutant mRNA for TA. Additionally, we found that single-stranded RNA injections of this 25 nt element from act-5 into the intestine of wild-type larvae led to higher levels of adapting gene (act-3) mRNA. Different models have been proposed to underlie the modulation of gene expression during TA including chromatin remodeling, the inhibition of antisense RNAs, the release of transcriptional pausing, and the suppression of premature transcription termination, and our data clearly show the importance of the regulatory region of the adapting gene in this particular act-5/act-3 TA model. Our findings also suggest that RNA fragments can modulate the expression of loci exhibiting limited sequence similarity, possibly a critical observation when designing RNA based therapies.
Topics: Animals; Caenorhabditis elegans; Acclimatization; RNA; RNA, Messenger; Nucleotides
PubMed: 37384903
DOI: 10.1371/journal.pgen.1010806