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 829 records · Page 46Linked to original sources
PubMed2002

Preconditioning and postresuscitation injury.

A major challenge in improving cardiac arrest survival is organ injury that occurs after the return of spontaneous circulation. This postresuscitation injury may result in as many as 90% of such patients not surviving to hospital discharge. Preconditioning, an adaptive physiologic response found in multiple organs and species, may help protect against such injury of ischemic tissue when reperfused at the return of spontaneous circulation. A better understanding of how preconditioning may alter postresuscitation injury is important for two major reasons. First, it is one of the most protective adaptations currently known in nature that attenuates ischemia-reperfusion injury. Pharmacologic and nonpharmacologic means to quickly trigger and perhaps augment this response have the potential to greatly improve survival from the global ischemia of cardiac arrest. Second, potential targets of preconditioning-such as the adenosine triphosphate-sensitive potassium channel and NAD(P)H oxidases-likely play important roles in the postresuscitation phase of cardiac arrest, and their modification may be important components of future treatment for patients with return of spontaneous circulation. The evidence for postresuscitation injury at the cellular level and its modification by preconditioning are discussed.

Cells, Cultured↗
PubMed1999

Water vapor absorption in arthropods by accumulation of myoinositol and glucose

Hydrophilic soil arthropods have been thought to respond to soil desiccation exclusively by migrating to deeper soil layers. Numerous studies have shown that their survival below 90 percent relative humidity dry weight, is limited to hours. However, little attention has been paid to physiological adaptations to more realistic desiccation regimes, such as at the permanent wilting point of plants (98.9 percent relative humidity). A water vapor absorption mechanism is described that allows a common soil collembolan, Folsomia candida, to remain active down to below the permanent wilting point. A reevaluation of the water physiology of this widespread and diverse animal group is required.

Journal Article↗
PubMed1984

The effect of water acidification on prolactin cells and pars intermedia PAS-positive cells in the teleost fish Oreochromis (formerly Sarotherodon) mossambicus and Carassius auratus.

Although exposure to acid water (pH 3.5) induces severe and prolonged reduction in plasma osmolarity and total plasma calcium concentration in tilapia (Oreochromis mossambicus) and goldfish (Carassius auratus), the responses of the hypophyseal cells are clearly different. In tilapia, the size of the rostral pars distalis of the pituitary gland is enlarged as a result of the increase in size and number of prolactin cells. The pars intermedia PAS-positive (PIPAS) cells are not noticeably changed. Conversely, in goldfish, prolactin cells are unaffected, whereas the number of enlarged PIPAS cells increases markedly. Stimulation of prolactin secretion may be responsible for the partial restoration of plasma osmolarity and calcium levels observed in tilapia after two weeks exposure to acid water. Prolactin cells apparently play a role in the adaptation to acid stress by counteracting osmoregulatory disturbances. Goldfish show no restoration of plasma osmolarity during the course of the experiment. Plasma calcium levels tend to increase. Although prolactin may have an osmoregulatory function in goldfish under steady state conditions, goldfish prolactin cells do not seem to participate in the physiological adaptation to environmental changes that disturb water and ion homeostasis. The function of PIPAS cells in tilapia remains unclear and is apparently unconnected with ion regulation. The observations on these cells in goldfish are consistent with the hypercalcemic activity suggested for them.

Animals↗
PubMed2007

Heme oxygenase-1 expression in premature and mature neonates during the first week of life.

Newborns are exposed to mechanical and oxidative stress during labor and to relative hyperoxia thereafter during the course of adaptation to the extrauterine conditions. Part of the adaptation mechanism is the rapid degradation of fetal hemoglobin and the oxidation of its heme moiety by heme oxygenases (HOs). Heme oxygenase-1 enzyme (HO-1) is the inducible isoform, which is induced by and protective against oxidative stress. We hypothesized that HO-1 may play a role in the physiological adaptation of newborns. We therefore measured the HO-1 mRNA expression with cRT-PCR during the first week after birth in healthy mature and premature newborns. We found that HO-1 was induced until day 2 or 3 after birth, but its level had dropped below the birth HO-1 mRNA level by the end of the first week. HO-1 levels and inducibility were similar in mature newborns and premature newborns. The fact that HO-1 was inducible even in gestation week 26 suggests that HO-1 plays an important role in the early adaptation processes.

Gene Expression↗
PubMed2005

Counteracting selective regimes and host preference evolution in ecotypes of two species of walking-sticks.

The evolution of ecological specialization has been a central topic in ecology because specialized adaptations to divergent environments can result in reproductive isolation and facilitate speciation. However, the order in which different aspects of habitat adaptation and habitat preference evolve is unclear. Timema walking-stick insects feed and mate on the host plants on which they rest. Previous studies of T. cristinae ecotypes have documented divergent, host-specific selection from visual predators and the evolution of divergent host and mate preferences between populations using different host-plant species (Ceanothus or Adenostoma). Here we present new data that show that T. podura, a nonsister species of T. cristinae, has also formed ecotypes on these host genera and that in both species these ecotypes exhibit adaptive divergence in color-pattern and host preference. Color-pattern morphs exhibit survival trade-offs on different hosts due to differential predation. In contrast, fecundity trade-offs on different hosts do not occur in either species. Thus, host preference in both species has evolved before divergent physiological adaptation but in concert with morphological adaptations. Our results shed light onto which traits are involved in the initial stages of ecological specialization and ecologically based reproductive isolation.

Adaptation, Biological↗
PubMed1993

Amygdaloid central nucleus lesions and cholinergic blockade attenuate the response of the renal peripheral benzodiazepine receptor to stress.

Previous research has demonstrated that the density of peripheral benzodiazepine receptors (PBR) in rat kidney rapidly drops following exposure to 80 min of stress. The present experiments examined the contribution of the central and autonomic nervous systems in mediating this effect. Ibotenic acid lesions of the amygdaloid central nucleus (ACe), but not the lateral and basolateral amygdala, diminished the magnitude of the reduction in renal PBR binding caused by stress. Pretreating rats with methyl-scopolamine also inhibited the response of the PBR to stress. Adrenergic blockade with nadolol was ineffective. In order to test whether the PBR was under direct or indirect neural control during stress, unilateral renal denervation was performed. The stress-induced reduction in PBR binding persisted in denervated kidneys revealing that any neural control over the PBR that might exist must be indirect. Together the results suggest that the CNS may be involved in regulating the PBR during stress through the activation of intermediate, possibly hormonal, factors. The involvement of the central nervous system in the modulation of the PBR indicates the relevance of the PBR to physiological adaptations to stress.

Acetylcholine↗
PubMed1989

Sports nutrition. Approaching the nineties.

A sophisticated appreciation of the role of nutrition in athletic performance has been made possible by increasing knowledge of the physiology of exercise. The nutritional issues of training are of primary importance, since this occupies most of the athlete's effort. The nutritional support of an intense daily training programme includes an appropriately high energy intake, predominantly in the form of carbohydrate in order to continually replenish muscle glycogen stores. Recent review of the protein needs of athletes indicates that requirements may be substantially above those of sedentary subjects, to account for the oxidation of amino acids during exercise as well as the retention of nitrogen during periods of muscle building. However, these increased requirements are likely to be met by the generous protein intakes anticipated in a high energy diet. The same would seem to hold true for micronutrient considerations, although there is no evidence that vitamin requirements are considerably increased by exercise. Nevertheless, a high energy diet chosen from a sufficiently varied range of foods should allow micronutrient intakes well in excess of population recommended dietary intake levels. Current interest is focused on the mineral status of athletes, particularly that of iron and calcium. In the case of iron, there is a possibility that the increased level of loss by some endurance athletes will not be met by their usual dietary patterns. Screening for early signs of iron deficiency, and appropriate supplementation and dietary counselling seem warranted in high risk groups. Competition poses the challenge of identifying possible factors limiting performance, and taking steps to delay or reduce these. Of paramount importance is body temperature regulation through the maintenance of hydration levels. This issue has long been recognised, but recent studies of gastric emptying and the benefits of carbohydrate supplementation during exercise have caused an update of the advice to athletes regarding fluid intake during exercise. It now seems possible to simultaneously achieve fluid and carbohydrate requirements for endurance exercise within a wide range of choice of beverages containing up to 10% carbohydrate. Concern about the adequacy of carbohydrate fuel stores in endurance exercise situations is also well known. The recognition that training achieves various physiological adaptations to enhance the lifespan of fuel stores has taken away some of the attention previously focussed on carbohydrate-loading techniques.(ABSTRACT TRUNCATED AT 400 WORDS)

Humans↗
PubMed1991

Mathematical modeling of acute and chronic cardiovascular changes during Extended Duration Orbiter (EDO) flights.

The Extended Duration Orbiter (EDO) program aims to extend the capability of the Shuttle orbiter beyond its current 7-10 day limit on mission duration. This goal is to be accomplished in steps, partly due to our limited knowledge of the physiological changes resulting from long-term exposure to weightlessness and their likely influence on critical mission operations involved in EDO flights. Answers to questions related to physiologic adaptation to weightlessness are being actively sought at the present time to help implement the EDO program. In the cardiovascular area, the loss of orthostatic tolerance is a medical concern because of its potential adverse effects on crew performance and safety during reentry and following return to earth. Flight and ground-based physiologic studies are being planned to understand the mechanism and time course of spaceflight-induced orthostatic intolerance and to develop effective countermeasures for improving post-flight cardiovascular performance. Where feasible, these studies are aided by theoretical analyses using mathematical modeling and computer simulation of physiological systems. This paper is concerned with the application of proven models of circulatory and cardiovascular systems in the analysis of chronic cardiovascular changes under weightless conditions.

Cardiovascular Deconditioning↗
PubMedDate not supplied

Interpreting the electronic fetal monitor. Strategies for management.

Electronic fetal monitoring offers the practitioner involved in the intrapartum care of women a mechanism to validate the fetus' physiologic adaptation to the labor and delivery experience. Utilizing a predetermined framework for constant assessment of fetal well-being will assist the clinician in the bedside management of these patients. This pathway of reassurance for fetal evaluation is an effective tool in the intrapartum observations of the fetus. If the fetus can demonstrate his physiologic well-being, labor may continue. However, if there are no signs of reassurance, immediate delivery of the fetus should be considered.

Acidosis↗
PubMed2001

Menopause and aging with disability.

Aging involves change and adaptation to change. The normal or usual changes of aging often have significantly greater impact on an individual whose disability has limited his or her physical or socioeconomic reserves. The aging process itself may be accelerated by overuse and compensatory mechanisms. The changes of aging have unique features in damaged body systems that exhibit physiologic adaptations. The changes of aging therefore often result in secondary impairments, leading to secondary disability. New adaptations or repeated rehabilitation are needed to regain the equilibrium among biologic, psychosocial, and environmental influences. Disabled women do not seem to have a significantly different experience of menopause from other women, but postmenopausal changes-accelerated bone loss and increased risk of heart disease-do appear to carry greater risk in those with mobility impairment. Hormone replacement therapy has both greater potential benefit and greater potential risks. Review of these issues makes evident the great need for research in the area of aging with disability, improvement in physician and consumer education, and future health care planning.

Aging↗
PubMed1991

The heart in hypertension.

Knowledge concerning the functional and structural changes of the heart in hypertension has increased remarkably over the past three decades. These changes may not at all be the same as with other diseases associated with increased afterload since the etiology, pathophysiological mechanisms, and other associated diseases are very different. Hemodynamic alterations associated with hypertension have a major role in the adaptive cardiac changes; but recent knowledge indicates that they are not exclusive. Nonhemodynamic factors are also very important; they not only include the now-accepted demographic considerations of age, race, gender and associated diseases but also consider newly discovered growth factors as well as prior and present therapy. The heart that provides a physiological adaptation to the increasing overload produced by disease in order to stem the tide from eventual cardiac failure also confers an independent risk of premature cardiovascular morbidity and mortality. It is too early to infer that reversal of the LVH reverses this risk. But, even if this does occur, mechanisms other than only LVH reversal must be considered. Therefore, at this time, the implications and consequences of reversed LVH has yet to be demonstrated.

Animals↗
PubMed1998

Effects of circadian mutations and LD periodicity on the life span of Drosophila melanogaster.

The pervasive occurrence of circadian clocks throughout the living world underlines their adaptive value. Nonetheless, there is surprisingly little evidence for a negative impact, on any animal species, of a constant discrepancy between the environmental and endogenous periods. Male Drosophila melanogaster per mutants with altered circadian periods were compared to the wild type in two different LD schedules. Life span was used as a global index of physiological adaptation. The life span of the mutants was significantly reduced by up to 15% for the flies whose period differs most from that of the wild type. A reduction was observed even when flies were kept in an LD schedule fitting a mutant period. The LD schedule made no significant difference on its own, but the authors found evidence for an interaction between genotype and LD schedule in determining life span. These results are consistent with the importance of the circadian clock in maintaining internal temporal order independent of environmental cycles. Nonetheless, a large difference between the environmental and endogenous periods has a measurable impact.

Alleles↗
PubMed1989

New perspectives on left ventricular hypertrophy: anatomy, physiology, and significance.

The advent of echocardiography has added an important and sensitive tool for assessment of left ventricular hypertrophy (increased left ventricular mass). Recent echocardiographic studies in large population-based samples suggest an epidemic of left ventricular hypertrophy. Preliminary data suggesting important prognostic importance for such left ventricular hypertrophy (independent of standard risk factors) has fueled interest in the development, determinants, and other features of the hypertrophy. Hemodynamic and neurohumoral factors are the most prominent stimuli to adaptive (physiologic) myocardial hypertrophy, which can progress to maladaptive (pathologic) hypertrophy. The overall blood pressure experience, overweight, the cardiovascular response to recurrent psychosocial stress and physical activity level are four important correlates and potential determinants of left ventricular mass in various urban-suburban populations. Determination of the relative contributions and interrelations of these and other factors (such as heredity) to various forms of left ventricular hypertrophy found in various demographic groups warrants intensive investigation.

Cardiomegaly↗
PubMed1980

A philosophical commentary. Stress: a redefinition.

Concepts dealing with stress and adaptation, even though useful, leave many unanswered questions. This paper touches on some of these ambiguities and outlines a broader and more encompassing philosophical approach to the subject.

Adaptation, Physiological↗
PubMed1977

[The influence of different feeding regimens on the capacity of lipolysis and ketogenesis during the neonatal period (author's transl)].

The capacity of lipolysis and ketogenesis as well as blood glucose homeostasis is studied in full-term newborn infants on different feeding formulas during the first days of life. Only with the aid of an oligosaccharide compound, carbohydrates can be administered in sufficient quantities, about 7 g/kg X 24 h, so that fat mobilization and ketogenesis are almost completely suppressed. This is not achieved by a regimen mimicing breast feeding in that no milk feeding takes place during the first day, nor by feeding maximal quantities of milk as soon as possible nor by administration of a mixed formula consisting of 10% glucose and milk. Though by early ingestion of large volumes of milk which without introducing tube feeding cannot be further enhanced total caloric intake almost equals the amount attained by the oligosaccharide formula the proportion of carbohydrates in respect to the latter only amounts to one third. In summing up the data reported herein demonstrate that the energy requirements of neonates cannot be supplied by usual dietary regimens, mainly due to the limitation of volume newborn infants can drink voluntarily. As a result of a deficiency in available carbohydrate lipolysis is stimulated in adipose tissue and ketosis arises. These are physiological adaptions resulting in increased availability of free fatty acids and ketone bodies which are easily utilized and thus satisfy the caloric requirements of the newborn infant.

Blood Glucose↗