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 811 records · Page 45Linked to original sources
PubMed2006

Animals, energy, and water in extreme environments: perspectives from Ithala 2004.

Animals occupy an impressive range of environments, and many approach the limits of conditions that are compatible with life. Such environments are often characterized by low productivity, and survival depends on abilities to maintain levels of hydration sufficient for biochemical reactions and an adequate level of energy turnover. Specific adaptations for acquiring and conserving water affect the intake and utilization of energy that is available for growth and reproduction. Almost any benign, historically stable environment can become hostile if conditions change, and the severity of challenges to animals depends on temporal as well as spatial factors that are related to the intensity and duration of harsh conditions (e.g., drought). Animals have responded to such changes through avoidance, phenotypically plastic adjustments, and evolutionary changes in genomic structure. Here we present an overview of research findings presented at a session of the Third International Conference of Comparative Physiology and Biochemistry. We hope such a synthesis will stimulate new directions in research that address biological responses to environmental change. In this context, we believe that challenging environments in Africa might provide increasingly useful sites for biological investigations relating to the application of comparative and evolutionary approaches toward a deeper understanding of physiological adaptation.

Acclimatization↗
PubMed1983

Modification of liver mitochondrial lipids and of adenine nucleotide translocase and oxidative phosphorylation by cold adaptation.

The decrease in respiration rate following thyroidectomy is preceded by changes in the lipid composition of the mitochondrial membrane (Hoch, F.L., Subramanian, C., Dhopeshwarkar, G.A. and Mead, J.F. (1981) Lipids 16, 328-334) and in concert, changes in the kinetic parameters of the adenine nucleotide translocase (Mak, I.T., Shrago, E. and Elson, C.E. (1981) Fed. Proc. 40, 398). To demonstrate that physiological adaptation also involves this sequence of events, rats were housed at 8 degrees C for 3-4 weeks. Cold adaptation resulted in a modest (5%) increase in the unsaturation index for the mitochondrial fatty acids comprised of a significant increase in arachidonic acid and a reciprocal decrease in linoleic acid. Phospholipid analysis indicated that cold adaptation increased the mitochondrial phosphatidylethanolamine and reciprocally decreased the phosphatidylcholine content. Concomitantly, cold adaptation resulted in 25-30% increases in rat liver mitochondrial respiratory activities without changing the respiratory control or ADP/O ratios. The kinetic parameters of the adenine nucleotide translocase were determined by the back-exchange method (Pfaff, E. and Klingenberg, M. (1968) Eur. J. Biochem. 6, 66-79). At 0-4 and 10 degrees C, the Vmax and Km of the cold-adapted rat liver adenine nucleotide translocase were not distinguishable from the control values. The Ki values determined by Dixon plot studies for atractylate and palmitoyl-CoA were also comparable between the two groups. However, at 25 and 37 degrees C, cold-adapted rat liver adenine nucleotide translocase exhibited a 20% increase in Vmax and a 20% decrease in Km for external ADP. The results suggest that one adaption to a cold environment involves hormone-mediated changes in the lipid composition in the mitochondrial membranes which in turn modulate the adenine nucleotide translocase and subsequent respiratory activities.

Acclimatization↗
PubMedDate not supplied

[Biomedical results of the Space Shuttle Orbital Flight Test Program].

On July 4, 1982 the Space Shuttle Columbia landed at Edwards Air Force Base, California, thus successfully completing the fourth and last in a series of Orbital Flight Tests (OFT) of the Space Transportation System (STS). The primary goal of medical operation support for the OFT was to assure the health and well-being of flight personnel during all phases of the mission. To this end, the crew health status was evaluated preflight, inflight and postflight. Biomedical flight test requirements were completed in the following areas: physiological adaptation to microgravity, cabin acoustical noise, cabin atmospheric evaluation, radiation dosimetry, crew exercise equipment evaluation and a cardiovascular deconditioning countermeasure assessment.

Air Pollution↗
PubMed2004

Is it normal for multiples to be smaller than singletons?

This section discusses fetal growth in multiple pregnancy from various perspectives. Whereas the entire 'fetal mass' of a multiple pregnancy can exceed the 90th birth weight percentile of a singleton of the same gestational age, the individual fetuses might exhibit growth patterns compatible with adaptation to the limited uterine environment. Adaptation can take the form of relative growth restriction (i.e. discordance), whereby not all fetuses show a decelerating growth pattern. When adaptation fails, fetal growth is genuinely restricted. However, even in cases with significant discordance, about 40% of the smaller twins weigh above the 10th birth weight percentile. The key in these circumstances might be found in the ability to recognize the transition from the physiologic adaptation into the pathologic process of growth restriction.

Embryonic and Fetal Development↗
PubMed2002

Delayed effects of cold stress on immune response in laboratory mice.

This study was undertaken to examine the trade-off between the cost of thermoregulation and immune function in laboratory mice. Mice were maintained either at 23 degrees C or cold exposed at 5 degrees C for 10 days. Then, they were immunized with sheep red blood cells. Thus, the cold-exposed mice had either experienced or not experienced cold stress prior to immunization. Cold stress elicited a substantial increase in food intake, accompanied by a significant reduction in food digestibility. An increase in mass of metabolically active internal organs (small intestines, heart and kidney) was observed in cold-exposed mice. These findings reassured us that costs of increased thermoregulation caused by cold stress were substantial. The immune response of mice exposed to long-lasting cold stress was significantly lower, but immune response was not affected in short-exposed mice. Differences in immune response between experimental groups accompanied changes in mass of immunocompetent organs (thymus and spleen). Our findings indicate that studies of trade-offs should account for the fact that resource reallocation in response to an environmental challenge may not be immediate. In fact, resource reallocation may be postponed until the new environmental state becomes permanent or until an organism attains physiological adaptation to the current conditions.

Animals↗
PubMed1993

Effects of acute ethanol doses or dietary phenobarbitol with carbon tetrachloride exposure on vitamin A status of rats.

Hepatotoxins such as ethanol and CCl4 are known to adversely affect vitamin A metabolism, although the effects of acute exposure to these agents have received less evaluation. The purpose of this study was to determine the effects of vitamin A status after a series of acute ethanol doses or a series of CCl4 inhalation challenges with concurrent phenobarbital exposure in the diet of rats. The depressed hepatic vitamin A seen after one ethanol dose was not sustained after repeated dosings. However, the significantly increased urine and liver radiolabeled vitamin A recovery after three acute ethanol exposure periods suggests adaptive physiologic and metabolic changes after the initial dose. The results of repeated CCl4/phenobarbital dosings on vitamin A status paralleled, for the most part, the ethanol results. Thus, the initial acute exposure of hepatotoxic agents causes metabolic changes that are not fully sustained as the animal adapts to these challenges.

Alcoholic Intoxication↗
PubMed1986

Adaptations in lipid metabolism of bovine adipose tissue in lactogenesis and lactation.

The timing and magnitude of metabolic adaptations in adipose tissue during lactogenesis and lactation were determined in first lactation bovines. In vitro rates of lipogenesis and palmitate esterification were measured to estimate in vivo synthesis. Lipolysis was measured in the basal state and as maximally stimulated by norepinephrine or epinephrine to estimate physiological adaptations as well as the changes in catecholamine responsiveness. Subcutaneous adipose tissue was biopsied at -1, -0.5, +0.5, 1, 2, and 6 months from parturition. From 1 to 0.5 months prepartum there was a 54% reduction in lipogenesis, a 16% reduction in esterification, a 54 and 77% increase in norepinephrine- and epinephrine-stimulated free fatty acid (FFA) release, respectively, and a 28% increase in epinephrine-stimulated glycerol release. The immediate postpartum period (0.5 and 1 month) was marked by a decrease in lipogenesis to 5% and esterification to 50% of -1 month rates. During this period, norepinephrine-stimulated FFA release increased 50% above -1 month rates, epinephrine-stimulated FFA release increased 128%, and norepinephrine- and epinephrine-stimulated glycerol release increased 30 and 87%, respectively. Midlactation (2 and 6 months) was marked by a dramatic rebound in lipogenesis and esterification to 14-fold and 2.5-fold prepartum rates, respectively. Basal glycerol release doubled during this period, while basal FFA release declined to near prepartum levels. Catecholamine-stimulated FFA and glycerol release decreased from the peak during midlactation, but remained elevated compared to prepartum levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1997

Effects of shear stress on wound-healing angiogenesis in the rabbit ear chamber.

Recent studies indicate that wall shear stress plays a significant role in the physiological adaptation of the vascular system. This study focused on the effect of sustained wall shear stress on wound-healing angiogenesis by exploring the morphologic and hemodynamic changes in developing microvessels in vivo through the tissue repair process. Rabbits were treated with the alpha 1 blocker prazosin (50 mg/L in water) orally from Day 0 to Day 23 after implantation of ear chambers to increase peripheral blood flow. The microvasculature in the chamber was recorded from Day 7 to Day 23 by using an intravital videomicroscope. The relative area of the chamber covered by vascularized tissue (%), the rate of ingrowth (mm2/day), the total vascular area (mm2), and the wall shear stress level (dyne/cm2) in venules (diameter in 20-40 microns) were quantified using a computerized image analysis system. The relative area increased significantly in the prazosin-treated animals from Days 7 to 19. The chamber of the treated group was completely covered with vascularized tissue earlier than that of the control group. The final total vascular area was larger by 21% in the treated group. The time course of shear stress in the treated group showed an initial elevation (1.44 times increase vs the control) followed by a gradual decrease toward the control level. These findings suggest that wound-healing angiogenesis may be partly involved in the adaptive response of microvasculature to shear stress.

Adrenergic alpha-Antagonists↗
PubMedDate not supplied

[The super-marathon run (Spartathlon, 248 km): variations in blood gastrin].

Serum gastrin levels were determined in 21 male runners aged 21-57 years old before and after an ultra marathon (Spartathlon, Athens-Sparta, 248 km). 13 participants (group B) arrived to Sparta after a continuous run of 24-35 hours, while 8 stopped after 95-151 km (group A). The stress associated with such a strenuous run has resulted a 35% decrease of gastrin in group A and a 46% rise in group B. Gastrin levels (post-race) of group B were 56% lower than those of group A. The regulatory mechanisms of serum gastrin levels and the physiological adaptations related to such an exhaustive exercise are discussed.

Adult↗
PubMed1983

Biomedical results of the Space Shuttle orbital flight test program.

On July 4, 1982, the Space Shuttle Columbia landed at Edwards Air Force Base, CA, thus successfully completing the fourth and last in a series of Orbital Flight Tests (OFT) of the Space Transportation System (STS). The primary goal of medical operations support for the OFT was to assure the health and well-being of flight personnel during all phases of the mission. To this end, crew health status was evaluated preflight, inflight, and postflight. Biomedical flight test requirements were completed in the following areas: physiological adaptation to microgravity, cabin acoustical noise, cabin atmospheric evaluation, radiation dosimetry, crew exercise equipment evaluation, and a cardiovascular deconditioning countermeasure assessment.

Aerospace Medicine↗
PubMed1993

Ontogeny of water sorption-desorption in the perinatal rat.

In mammals, birth marks a transition to a cold and gaseous environment that requires rapid physiologic adaptations limiting heat and water loss. In this study, the perinatal Sprague-Dawley rat was utilized as a model to study the behavior of water binding to the external body surface following birth. Water sorption and desorption were quantified by measurement of skin surface capacitance following water loading using a dry ring electrode system. The results indicate that the external body surface of the newborn rat is highly hydrophobic. This hydrophobicity is manifested by the rapid desorption of water (amniotic fluid) following birth as well as marked limitation of water sorption after birth. Post-natally, this hydrophobic effect is gradually lost over the first 3 d of life. Somatic growth retardation results in retention of this surface property, whereas extraction of the skin surface with acetone abolishes it. Morphologic and functional (water binding) studies performed after stripping the stratum corneum with acrylic adhesive strongly suggest a physiologic role for the periderm in determining this postnatal hydrophobic effect. These data are interpreted as evidence for a novel thermoregulatory mechanism in the rat during adaptation to post-natal life.

Absorption↗
PubMed1992

[Family intervention according to Roy].

The author presents a care plan based upon Sister Callista Roy's conceptual model, that is recognized as well suited to the family system. This, the first of two-part series, focuses on the first two steps of the care plan--the theoretical and practical aspects of data collection and data analysis. The subjects are a single mother and her son. During the first level of evaluation of the family system, the nurse observes and explores the family system's behavior as well as that of each of the family members using the four modes of adaptation: physiological needs, self-concept, role function, and interdependence relations. During the second level of evaluation, the nurse identifies observed and reported stimuli or factors within the family environment that influence observed behaviors. During the data analysis, the nurse determines if the reported or observed behaviors are adaptive or non-adaptive toward maintaining the bio-psycho-social integrity of the family. The nurse also determines if the behaviors allow for achievement of identified goals. The nurse establishes links between the behaviors and the stimuli, classes and organizes the findings, and formulates an appropriate nursing care plan. Next month's article will focus on the planning, implementation and evaluation of the nursing care plan. It will focus equally on the ways in which the nurse can facilitate the family's adaptation.

Family↗
PubMed2007

Transcriptomic adaptations in rice suspension cells under sucrose starvation.

Sugar is an important resource for energy generation and developmental regulation in plants, and sucrose starvation causes enormous changes in cellular morphology, enzyme activities and gene expression. Genome-wide gene expression profiling provides a comprehensive knowledge of gene expression under nutrient depletion and senescence; however, that of a monocot model plant, rice, under sucrose depletion is still under investigation. Here, the time-course monitoring of gene expression profiles in sucrose-starved rice (Oryza sativa cv Tainung67) suspension cells was investigated by 21495 probes contained in Agilent rice chip. In sucrose-starved cells, the induced vacuolar biogenesis coincided with significantly upregulated transcripts of H+-pyrophosphatase, delta-TIP, one putative alpha-TIP, several vacuolar proteases and proteinase inhibitors, and one OsATG3. To survey the overall metabolic adaptations under sucrose depletion, the genes with significantly altered expression level were incorporated into multiple metabolic pathways. Most genes encoding enzymes involved in biosynthesis and degradation pathways of various macromolecules were comprehensively down-and upregulated, respectively, with sucrose starvation. Transcriptional regulation of gene expression is important for physiological adaptations to environmental stress, and many transcription factors, including bZIPs, NACs, and WRKY, showed significant increase in transcriptional level under sucrose starvation. Concurrently, statistical analysis revealed that their corresponding consensus cis-elements, such as ABA-responsive element, CACG, ACI, ACII and CTTATCC, were frequently found in the promoter regions of many sucrose starvation-upregulated genes. Particle bombardment-mediated and luciferase activity-based transient promoter assays revealed the CTTATCC, derived form TATCCA, and the AC motifs to be promising sucrose-starvation responsive activators in rice suspension cells.

Base Sequence↗
PubMed2005

Fetal programming: the perspective of single and twin pregnancies.

Multiple pregnancy is associated with increased risk of adverse consequences for both mother and fetus(es), including increased rates of maternal hypertension and pre-eclampsia, spontaneous abortion, Caesarean delivery, low birthweight, birth prematurity, perinatal mortality, admission to neonatal intensive care and extended length of care, respiratory distress, cerebral palsy, developmental delay, contact with disability services and mortality to age 5 years. Premature birth, which affects 97% of triplets and 53.3% of twins in Australia, is not the sole factor involved. The rate of multiple pregnancy in Australia is 1.7%. This compares to 22.1% for pregnancies resulting from assisted reproduction technology (ART). As a result, 21.8% of babies born from ART are from a multiple pregnancy, in comparison to the USA where the majority of babies born from ART are from a multiple pregnancy. Additionally, the population rate of multiple births is rising due to the more frequent use of ART and continued multi-embryo transfers, which is operating against a background of rising implantation rates within ART clinics. Twins have been of interest from a programming perspective. However, analysis of associations between crude birthweight and subsequent metabolic risk factors or mortality in adulthood from chronic disease indicate that adaptations in pregnancy to support multi-fetal growth are not identical to fetal growth restriction in singleton pregnancies. Indeed, the process of 'maternal constraint' is incompletely understood and confounds such comparisons. From a programming perspective, it is a challenge to identify in twin pregnancies the transition from physiological adaptation to pathological growth restriction. Growth disparity between twins has been more illuminating of subtle adverse effects for the smaller of twin pairs in both blood pressure and insulin resistance in adulthood. Interestingly, these effects can be observed in both dizygotic and to a lesser degree in monozygotic twins, which indicates a role for both genetic and environmental factors in these measures. This suggests that, consistent with experimental studies in other species, the relationship between impaired growth in utero and chronic disease in later life is not simply mediated by a common genetic pathway.

Australia↗
PubMedDate not supplied

Postfreeze reduction of locomotor endurance in the freeze-tolerant wood frog, Rana sylvatica.

Considerable study has focused on the physiological adaptations for freeze tolerance in the wood frog, Rana sylvatica, a northern species that overwinters within the frost zone, but little attention has been paid to the associated costs to organismal performance. Here we report that freezing causes transient impairment of locomotor endurance and adverse changes in exercise physiology that persist for at least 96 h. Wood frogs frozen at -2 degrees C for 36 h exhibited normal behaviors and hydro-osmotic status and near-normal metabolite (glycogen, glucose, and lactate) levels within 24 h after thawing began. However, when exercised to exhaustion on a treadmill, these frogs showed a 40% reduction in endurance as compared to sham-treated (unfrozen) controls, a reduction that persisted for at least 96 h. Previously frozen frogs exhibited higher rates of lactate accumulation during exercise than controls, suggesting that prior freezing forces greater reliance on the glycolytic pathways of energy production to support exercise. Given that this species breeds in late winter, when subzero temperatures are common, freezing may result in reduced fitness by hampering their ability to reach the pond, avoid predators, and successfully obtain mates.

Acclimatization↗
PubMed1976

The stress concept.

Explore the source record for details and available documents.

Adaptation, Physiological↗
PubMed2004

The genetic basis of high-altitude pulmonary oedema.

High-altitude pulmonary oedema (HAPE) is a potentially fatal condition affecting fit and previously well individuals at altitudes in excess of 3000 m. This article discusses the mechanisms of HAPE, considers the contribution of hypoxic pulmonary vasoconstriction and alterations in sodium transport to the pathological process. It discusses the various biochemical mediators such as nitric oxide (NO), endothelin-1 (ET-1), and the renin-angiotensin-aldosterone system (RAS) that may be involved and considers possible oxygen-sensing mechanisms involved in hypoxic adaptation such as hypoxia-inducible factor-1 (HIF-1). Those who have had HAPE once run an unpredictable but significant risk of recurrence; therefore, there may be a constitutional or genetic component in its aetiology. This paper considers the possible involvement of genes that may be involved in physiological adaptation to hypoxia (e.g., angiotensin-1 [AT(1)]-converting enzyme [ACE], tyrosine hydroxylase, serotonin transporter [5-HTT], and endothelial NO synthase [eNOS] genes). As yet, no formal association has been identified between an identified genetic polymorphism and HAPE, but genetic variation provides a possible mechanism to explain interindividual variation in response to hypoxia and enhanced or reduced performance at altitude.

Altitude Sickness↗