Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ADAPTATION, PHYSIOLOGICAL”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 595 records · Page 33Linked to original sources
PubMed1992

[Gene-enzyme system of alcohol dehydrogenase and adaptation of Drosophila to increased temperature].

Properties and allelic ADH (alcohol dehydrogenase) control in Drosophila melanogaster were studied upon flies' cultivation under conditions of hypotherm of different intensity and duration. Lines homozygotic for F allele (vg) and S allele (cn) of the Adh gene as well as genetically enriched experimental cn' and vg' populations containing a small number of AdhF/AdhS heterozygotes at the initial stage were used. It was found out that physiological adaptation of the species to momentary influence of elevated temperature is accompanied by modification of physical properties of ADH-F according to ADH-S. Constant influence (during the life span of 25 generations) of elevated temperature on the population changes its genetic structure, due to selective advantages of the S allele of Adh under these conditions.

Adaptation, Physiological↗
PubMed1999

Auditory-visual integration during multimodal object recognition in humans: a behavioral and electrophysiological study.

The aim of this study was (1) to provide behavioral evidence for multimodal feature integration in an object recognition task in humans and (2) to characterize the processing stages and the neural structures where multisensory interactions take place. Event-related potentials (ERPs) were recorded from 30 scalp electrodes while subjects performed a forced-choice reaction-time categorization task: At each trial, the subjects had to indicate which of two objects was presented by pressing one of two keys. The two objects were defined by auditory features alone, visual features alone, or the combination of auditory and visual features. Subjects were more accurate and rapid at identifying multimodal than unimodal objects. Spatiotemporal analysis of ERPs and scalp current densities revealed several auditory-visual interaction components temporally, spatially, and functionally distinct before 200 msec poststimulus. The effects observed were (1) in visual areas, new neural activities (as early as 40 msec poststimulus) and modulation (amplitude decrease) of the N185 wave to unimodal visual stimulus, (2) in the auditory cortex, modulation (amplitude increase) of subcomponents of the unimodal auditory N1 wave around 90 to 110 msec, and (3) new neural activity over the right fronto-temporal area (140 to 165 msec). Furthermore, when the subjects were separated into two groups according to their dominant modality to perform the task in unimodal conditions (shortest reaction time criteria), the integration effects were found to be similar for the two groups over the nonspecific fronto-temporal areas, but they clearly differed in the sensory-specific cortices, affecting predominantly the sensory areas of the nondominant modality. Taken together, the results indicate that multisensory integration is mediated by flexible, highly adaptive physiological processes that can take place very early in the sensory processing chain and operate in both sensory-specific and nonspecific cortical structures in different ways.

Acoustic Stimulation↗
PubMed1993

Introduction: exercise capacities and adaptations of people with chronic disabilities--current research, future directions, and widespread applicability.

This symposium addresses the unique physiological problems, current research, future needs, and widespread applicability for research involving people experiencing five major chronic disabilities within the United States: quadriplegia, paraplegia, mental retardation, multiple sclerosis, and poliomyelitis. Each author represents ACSM members who, by their distinguished research efforts, exemplify scientists who have demonstrated their dedication to the specific needs of these populations. The papers will give a brief description of the pathophysiology of the disability and the resultant effects upon the group's acute response to exercise and their physiological adaptations to exercise programs. Each paper will include reports on the state of current research and what benefits to that group could be expected if a major research breakthrough occurred. Additionally, the papers will indicate the major research questions currently confronting each population and a brief statement about the strategy needed to resolve these questions. If applicable, the authors will address how such a model (of the specific disability/disease) could be used to better understand the able-bodied response to exercise. The purpose of this symposium, therefore, was not only to better understand the effects of exercise on persons having chronic disabilities, but from a physiological point of view, to use what we know about the response of people with chronic disabilities to better understand the able-bodied response.

Adaptation, Physiological↗
PubMedDate not supplied

Winter swimming: healthy or hazardous?. Evidence and hypotheses.

Swimming in cold water during the winter season is an extreme sport, with fans all over the world. However, its effects on health have been debated. This article examines the hypothesis that the effects of winter swimming may depend on previous exposure to cold stimuli. Immersion in cold water in unaccustomed persons may lead to detrimental consequences, while, in regular winter swimmers, adaptive physiologic mechanisms increase tolerance to cold. Furthermore, these mechanisms may prevent the occurrence of a wide variety of diseases. Prospective studies and epidemiological data are needed to test this hypothesis.

Acclimatization↗
PubMed2005

The effects of local anesthetics on cellular hypoxia-induced gene responses mediated by hypoxia-inducible factor 1.

PURPOSE: Hypoxia (reduced oxygen availability) induces a series of adaptive physiological responses. At the cellular level, the adaptation includes a switch of energy metabolism from oxidative phosphorylation to anaerobic glycolysis, increased glucose uptake, and the expression of stress proteins related to cell survival. One of the most important transcription factors that activate the expression of oxygen-regulated genes is hypoxia-inducible factor 1 (HIF-1). We previously reported that halothane inhibits the hypoxia-induced HIF-1 activation. In this study, we investigated the effect of local anesthetics on HIF-1 activation and its downstream gene expression. METHODS: The established cell line Hep3B and SK-N-MC cells were exposed to 1% O2 with or without treatment by either lidocaine or bupivacaine. Expression of subunits of HIF-1, HIF-1alpha, and HIF-1beta was examined by Western blot using specific antibodies. Expression of mRNA of HIF-1 and the HIF-1-dependent genes was investigated by RT-PCR and reporter assay. RESULTS: Neither of the local anesthetics tested affected the accumulation of HIF-1alpha induced by hypoxia, nor did they affect NOC18-induced HIF-1alpha accumulation. Moreover, they had no effects on HIF-1-mediated hypoxia-induced gene expression. CONCLUSION: The local anesthetics lidocaine and bupivacaine did not affect the HIF-1-dependent cellular hypoxia-induced gene responses.

Anesthetics, Local↗
PubMed2001

Circulatory physiology in the developing embryo.

Knowledge of early developmental circulatory physiology has lagged behind advances in molecular cardiology. Cardiovascular physiology changes during embryonic development in a highly complex and carefully orchestrated manner, tightly correlated with structural development. Circulatory changes in early development include increasing heart rate, preload, and cardiac output; decreasing peripheral resistance; and increasing ventricular compliance, paralleling the increasing metabolic needs of the growing embryo. Newer techniques and the recent ability to study mammalian models of development have led to further insight into changes in myocardial and peripheral vascular physiology. The next major challenges include understanding the mechanisms regulating cardiovascular hemodynamics, normal physiologic adaptation of the growing embryo, and the physiology of abnormal cardiovascular development.

Biomechanical Phenomena↗
PubMedDate not supplied

[The effect of ultrahigh-frequency radiation on adaptation thresholds and the damages to blood system cells].

Cytologic investigations designed to study bone marrow, peripheral blood, spleen, and thymus of albino rats irradiated by an electromagnetic field, 2375, 2450, and 3000 MEGS, revealed structural and functional changes in populations of megakaryocytes, immunocompetent cells as well as of undifferentiated cells, and of other types of cells that are dependent on the intensity of irradiation and permit establishing the probability-threshold levels of exposure taking account of reactions of perception and physiologic adaptation together with compensatory and regenerative processes and the injury sustained. It is shown that changes in bone marrow cells differentiation and reproduction rather than integral shifts in the peripheral blood that acquire the utmost significance. Subjected to a particular scrutiny in the paper are blast cells, which cells' repopulation was noted to be getting increased in low-intensity exposure as were disturbances in their mitosis pattern.

Adaptation, Physiological↗
PubMed1992

Low to moderate intensity endurance training in healthy older adults: physiological responses after four months.

OBJECTIVE: To determine the physiological adaptations in previously sedentary healthy older men and women (mean age = 68) to a 16-week low-to-moderate-intensity exercise program. DESIGN: Randomized, controlled trial. SETTING: An exercise facility and testing laboratory in a gerontological research institute. PARTICIPANTS: Two-hundred forty-seven community-dwelling older persons free of significant cardiovascular, pulmonary, or uncontrolled metabolic disease, anemia, electrolyte abnormality, resting BP of 165/90 or greater, or chronic disease affecting the ability to exercise on a bicycle. INTERVENTION: Subjects were randomly assigned to either an exercise (n = 166) or attention control group (n = 81). Exercisers trained thrice weekly for 40 minutes on a cycle ergometer (5-minute warm up, 30 minutes at training heart rate (THR), 5-minute cool down). THR was set at 70% of peak heart rate attained on a maximal exercise test (mean = 115 +/- 15). Control subjects attended weekly group talks. Testing took place before and after the program. RESULTS: Peak attained oxygen uptake (VO2max) increased 8.5% in exercisers and decreased slightly in controls (p less than .001) and oxygen uptake at ventilatory threshold (VeT VO2) increased by 3.5% in exercisers and decreased by 3% in controls (p less than .001). This pattern of a greater increase in VO2max than VeT VO2 is different from that seen in young and middle-aged subjects. CONCLUSION: This study demonstrated that a large scale training program is feasible for healthy older people, that physiologic improvements can be measured after 16 weeks of low-to-moderate-intensity training, and that mechanisms of adaptation to exercise may be different in elderly subjects from those in younger ones.

Adaptation, Physiological↗
PubMed2005

Temporal changes in gene expression in the arcuate nucleus precede seasonal responses in adiposity and reproduction.

In anticipation of seasonal climate changes, Siberian hamsters display a strategy for survival that entails profound physiological adaptations driven by photoperiod. These include weight loss, reproductive quiescence, and pelage growth with shortening photoperiod and vice versa with lengthening photoperiod. This study reports gene expression changes in the hypothalamus of Siberian hamsters switched from short days (SD) to long days (LD), and also in photorefractory hamsters. Siberian hamsters were maintained in either LD or SD for 14 wk, conditions that generate physiological states of obesity under LD and leanness under SD. After 14 wk, SD lighting was switched to LD and gene expression investigated after 0, 2, 4, and 6 wk by in situ hybridization. Genes encoding nuclear receptors (RXR/RAR), retinoid binding proteins (CRBP1 and CRABP2), and histamine H3 receptor were photoperiodically regulated with significantly lower expression in SD, whereas VGF mRNA expression was significantly higher in SD, in the dorsomedial posterior arcuate nucleus. After a SD-to-LD switch, gene expression changes of CRABP2, RAR, H3R, and VGF occurred relatively rapidly toward LD control levels, ahead of body weight recovery and testicular recrudescence, whereas CRBP1 responded less robustly and rxrgamma did not respond at the mRNA level. In this brain nucleus in photorefractory animals, the CRABP2, RAR, H3R, and VGF mRNA returned toward LD levels, whereas CRBP1 and rxrgamma remained at the reduced SD level. Thus, genes described here are related to photoperiodic programming of the neuroendocrine hypothalamus through expression responses within a subdivision of the arcuate nucleus.

Adaptation, Physiological↗
PubMed2005

Aerobic training improves insulin sensitivity 72-120 h after the last exercise session in younger but not in older women.

The regular practice of aerobic training (AT) induces an improvement in insulin sensitivity (IS) in healthy younger women that persists until 96-120 h after the last exercise bout. Due to the dearth of research data, it still remains unclear whether a regular AT program can improve IS for such a period of time after the last training bout in healthy older women. To address this issue, we trained 14 younger and 8 older women 3 days per week during 6 months, and measured IS 3-5 days after the last training bout. AT consisted of 25-60 min sessions of running at 60-95% of maximal heart rate. Fat mass decreased (8%) in older women only. VO(2max) and fat-free mass increased in both groups. Only older women decreased bodyweight (4%) and subcutaneous adipose tissue (19%). Visceral adipose tissue decreased in none of the groups. The IS improved only in younger women (relative: 22%; absolute: 24%). The present findings suggest that in older women the improvement in IS following AT is short-lived and results mainly from the acute effect of the last training bout, whereas in younger women the chronic adaptations induced by AT are implicated, as the improvement in IS is maintained beyond the residual effect of the last training bout. From a clinical standpoint, our findings suggest that in older women AT should be performed every day to improve glucose metabolism, whereas in younger women an AT frequency (three times per week) allowing to induce and maintain chronic minimal physiological adaptations would be required.

Adaptation, Physiological↗
PubMed1995

Release of oxytocin within the supraoptic nucleus. Mechanisms, physiological significance and antisense targeting.

In addition to its secretion from neurohypophysial terminals, oxytocin (OT) is released within the hypothalamic magnocellular nuclei--the supraoptic (SON) and paraventricular nuclei--in response to various stimuli as mainly shown by microdialysis studies. During parturition and suckling, OT is released within the SON in a positive feedback role to further amplify its own local and/or neurohypophysial release depending upon the reproductive conditions. Whereas, for instance, intra-SON OT is important for appropriate OT secretion and milk ejection during suckling, it seems to be involved in the timing of the parturition process without directly affecting OT secretion during birth. As a consequence of various morphological and physiological adaptations of the OT system during lactation, the release pattern of OT into blood and within the SON is altered in response to other stimuli, like swim stress and peripheral osmotic stimulation. In addition, in lactating, but not virgin female or male rats, unilateral stimulation of the SON results in the release of OT, but not vasopressin or various amino acids, within the contralateral SON, which implicates a functional role of intranuclear OT in the plastic coupling of the paired SON during lactation. To manipulate OT synthesis and release, antisense targeting was used. Novel, acute effects (within 5 hours) of an OT antisense oligodeoxynucleotide on suckling-related parameters and, specifically, on the electrophysiological excitability of OT neurons as well as their ability to express the Fos-protein after CCK-8 are described. Since the OT content in the hypothalamo-neurohypophysial system was still unaffected at this time, antisense oligonucleotides may induce feedforward alterations in neuronal responsiveness which precede or parallel effects on neuropeptide synthesis. Taken together, the functional significance of OT released within the brain and into blood during reproduction provides an example of how a neuropeptide might regulate complex physiological and behavioral performances in a synergistic manner.

Adaptation, Physiological↗
PubMed2006

Environmental discontinuity hypothesis: Buffer dysfunctions as a source of human disease.

Adaptive physiologic buffers enable organisms to respond to environmental variation with appropriate plasticity. Modern humans have substantially remodeled their environment such that many interactions with the environment have become relatively discontinuous functions compared to the past. Examples include sunlight, temperature, and altitude. We propose that environmental discontinuity represents a Darwinian maladaptation and may promote disease by inducing buffer dysfunctions. Skin pigmentation is an adaptive, dynamic buffer that normalizes sunlight exposure to balance the potential harm of damaging rays with the importance of sunlight in driving systemic biologic functions such as melatonin and vitamin D. Due to lifestyle characteristics such as indoor-outdoor living, well-intended sun-avoidance campaigns, and inhomogeneous use of apparel and sunblock techniques, modern humans increasingly experience sunlight variation as a discontinuous function. The resulting skin pigmentation buffer dysfunction may promote diseases associated with over- or under-exposure to sunlight, the most striking example being melanoma. In addition to promoting discontinuity of sunlight exposure, sun-avoidance campaigns may undermine sun-dependent biologic pathways such as melatonin and vitamin D that appear to protect against cancer. These issues may partly explain the rise in melanoma rates despite the implementation of sun-avoidance campaigns. Also discussed is the potential role that discontinuous temperature variation associated with modern lifestyles plays in diseases such as viral infection, heart failure, and acute coronary syndromes. Acute discontinuous changes in pressure and oxygen levels related to air travel may contribute to autonomic dysfunction, venous thromboembolism, and viral infections. Therapeutic implications are discussed.

Adaptation, Physiological↗
PubMed2004

State transitions: an example of acclimation to low-light stress.

State 1-State 2 transitions ('state transitions') are a rapid physiological adaptation mechanism that adjusts the way absorbed light energy is distributed between photosystem I and photosystem II. They occur in both green plants and cyanobacteria, although the light-harvesting complexes involved are very different. Which aspects of the mechanism are conserved in green plants and cyanobacteria and which may be different, are discussed. It is shown that phycobilisome mobility is necessary for state transitions in cyanobacteria. A conserved cyanobacterial gene (rpaC) that plays a very specific role in state transitions has been identified. There is still debate about the physiological role of state transitions. Comparison of the growth properties of the rpaC deletion mutant with the wild-type gives us a way of directly addressing the question. It was found that state transitions are physiologically important only at very low light intensities: they play no role in protection from photoinhibition. Thus state transitions are a way to maximize the efficiency of light-harvesting at low light intensities.

Adaptation, Physiological↗
PubMedDate not supplied

[Osmotic tolerance and adaptation to hypotonic medium of Echinorhynchus gadi (Acanthocephala, Echinorhynchidae)].

Minimum of the osmotic pressure in the intestine of the cod corresponds to the osmotic pressure of sea water of 10%. The sorbtion level of neutral red by intact E. gadi remained practically unchanged after their maintenance in sea water of 8-10 to 30% during 24 hours (ecological optimum). Specimens of E. gadi transferred from 10 to 4% displayed compensatory recovery of the normal sorbtion level of the dye by the 5th-6th day of the experiment. The ability of Acanthocephala possessing extreme eutelia to a physiological adaptation is indicative of its not obligatory participation of mitotic processes in the acclimation.

Absorption↗
PubMed2006

Cyclitols and carbohydrates in leaves and roots of 13 Eucalyptus species suggest contrasting physiological responses to water deficit.

In many tree species, physiological adaptations to drought include the accumulation of osmotically active substances and/or the presence of particular compatible solutes, among them cyclitols. Recently, the cyclitol quercitol was identified in species of Eucalyptus, a diverse genus whose speciation is probably driven by adaptation to water availability. We subjected seedlings of 13 Eucalyptus species from different ecosystems ('mesic' and 'xeric') and different sub-generic taxonomic groups to 10 weeks of water deficit (WD) treatment. Pre-dawn water potentials (psi(pdwn)) and relative water content (RWC) were determined in shoots, and total osmolality, soluble low-molecular-weight carbohydrates and cyclitols were measured in leaves and roots. Responses to water deficit followed two distinct patterns: Eucalyptus species from 'mesic' environments adjusted concentrations of sucrose (through increased levels of sucrose and decreases in RWC) in response to water deficit, whereas 'xeric' species increased concentrations of quercitol (through reductions in RWC). In root tissues, only species from xeric environments contained high levels of quercitol and mannitol, increasing under WD conditions. We suggest that the former (mesic) strategy may be beneficial to respond to short-lasting drought conditions, because sucrose is easily metabolized, whereas the latter (xeric) strategy may relate to an effective acclimation to longer-lasting drought. These physiological response groups are also related to taxonomic groups within the genus.

Adaptation, Physiological↗
PubMed2005

Nutritional adaptation to seasonal climatic change: a study for rain-fed farmers in northeast Thailand.

Based on the author's study of anthropometry, energy expenditure and food consumption in four (pre-harvest, harvest, post-harvest and rainy) seasons among rain-fed rice growing farmers in Northeast Thailand, this article clarifies and discusses human adaptive (or maladaptive) strategies to seasonal climatic change. Total energy expenditure fluctuated markedly among the four seasons, but total energy intake did to a negligible extent. Change in body weight significantly differed between pre-harvest and post-harvest seasons, with a magnitude of 1.3 kg, or 2.3%, in males and 2.5 kg, or 4.3%, in females. Respiratory quotient (RQ) was the lowest in the post-harvest season when fat mass increased. These results demonstrated that physiological adaptation, through change in RQ in particular, to change in energy balance occurred in relatively short periods, and thus behavioral adaptation by means of changes in energy intake was observed not in specific seasons but in a year. The nutritional-ecological adaptive patterns of the rain-fed rice farmers were compared with those of various subsistence populations based on physical activity levels.

Adaptation, Physiological↗
PubMed2005

Adaptations in bacterial catabolic enzyme activity and community structure in membrane-coupled bioreactors fed simple synthetic wastewater.

Membrane-coupled bioreactors (MBRs) offer substantial benefits compared to conventional reactor designs for biological wastewater treatment. MBR treatment efficiency, however, has not been optimized because the effects of the MBR on process microbiology are poorly understood. In this study, the structure and function of the microbial communities growing in MBRs fed simple synthetic wastewater were investigated. In four starch-fed MBRs, the bacterial community substantially increased its alpha-glucosidase affinity (>1000-fold), while the leucine aminopeptidase and heptanoate esterase affinities increased slightly (<40-fold) or remained relatively constant. Concomitant to these physiological adaptations, shifts in the bacterial community structure in two of the starch-fed MBRs were detected by PCR-DGGE. Four of the bacterial populations detected by PCR-DGGE were isolated and exhibited specific growth rates in batch culture ranging from 0.009 to 0.22 h(-1). Our results suggest that bacterial communities growing under increasingly stringent nutrient limitation adapt their enzyme activities primarily for the nutrients provided, but that there is also a more subtle response not linked to the substrates included in the feed medium. Our research also demonstrates that MBRs can support relatively complex bacterial communities even on simple feed media.

Adaptation, Physiological↗