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PubMed2001

[Adaptation to hyperthermia and changes in peripheral blood leukocytes in humans].

Heating humans up to rectal temperature 39.0-39.5 degrees C induces a heat stress and a physiological adaptation. Blood cells were found to produce nitric oxide under these conditions, neutrophiles playing a major role in the process. In our opinion, the HSC 70 takes part in the process of the long cell adaptation augmenting the cells' functional activity. Hyperthermia leads to a massive temporal HSP 72 expression in the blood mononuclears. This expression seems to be due to alterations in the cellular proteins and to oxidative stress.

Adaptation, Physiological↗
PubMed1998

Thermoregulatory competence and behavioral expression in the young of altricial species--revisited.

The behavioral and physiological thermoregulatory capabilities of newborn and infant mammals have been studied for over half a century. Psychobiologists have noted that the infants of altricial species (e.g., rats) have physical and physiological limitations such that heat loss overwhelms heat production, thus forcing a reliance on behavioral thermoregulation for the maintenance of body temperature. Recent evidence, however, suggests that a modification of this view is justified. Specifically, throughout a range of moderately cold air temperatures, nonshivering thermogenesis by brown adipose tissue contributes significantly to the infant rat's behavioral and physiological adaptations to cold challenge. Given the prominent use of altricial species for the study of infant behavior, increased understanding of the infant's physiological responses to cold and the effect of thermal factors on behavior is warranted.

Adaptation, Physiological↗
PubMed2005

The subacute effects of exercise: concept, characteristics, and clinical implications.

Physical exercise represents a physiological stress to the organism producing acute integrative physiological adjustments, whereas repetitive and regular sessions of physical effort provoke chronic physiological adaptations that develop throughout the weeks of training and increase exercise capacity. The present work presents and discusses the concept of subacute effects of exercise, those physiological responses occurring between single bouts of exercise.

Adaptation, Physiological↗
PubMed1999

Performance and muscle fiber adaptations to creatine supplementation and heavy resistance training.

PURPOSE: The purpose of this study was to examine the effect of creatine supplementation in conjunction with resistance training on physiological adaptations including muscle fiber hypertrophy and muscle creatine accumulation. METHODS: Nineteen healthy resistance-trained men were matched and then randomly assigned in a double-blind fashion to either a creatine (N = 10) or placebo (N = 9) group. Periodized heavy resistance training was performed for 12 wk. Creatine or placebo capsules were consumed (25 g x d(-1)) for 1 wk followed by a maintenance dose (5 g x d(-1)) for the remainder of the training. RESULTS: After 12 wk, significant (P < or = 0.05) increases in body mass and fat-free mass were greater in creatine (6.3% and 6.3%, respectively) than placebo (3.6% and 3.1%, respectively) subjects. After 12 wk, increases in bench press and squat were greater in creatine (24% and 32%, respectively) than placebo (16% and 24%, respectively) subjects. Compared with placebo subjects, creatine subjects demonstrated significantly greater increases in Type I (35% vs 11%), IIA (36% vs 15%), and IIAB (35% vs 6%) muscle fiber cross-sectional areas. Muscle total creatine concentrations were unchanged in placebo subjects. Muscle creatine was significantly elevated after 1 wk in creatine subjects (22%), and values remained significantly greater than placebo subjects after 12 wk. Average volume lifted in the bench press during training was significantly greater in creatine subjects during weeks 5-8. No negative side effects to the supplementation were reported. CONCLUSION: Creatine supplementation enhanced fat-free mass, physical performance, and muscle morphology in response to heavy resistance training, presumably mediated via higher quality training sessions.

Adaptation, Physiological↗
PubMed2006

The unique 16S rRNA genes of piezophiles reflect both phylogeny and adaptation.

In the ocean's most extreme depths, pressures of 70 to 110 megapascals prevent the growth of all but the most hyperpiezophilic (pressure-loving) organisms. The physiological adaptations required for growth under these conditions are considered to be substantial. Efforts to determine specific adaptations permitting growth at extreme pressures have thus far focused on relatively few gamma-proteobacteria, in part due to the technical difficulties of obtaining piezophilic bacteria in pure culture. Here, we present the molecular phylogenies of several new piezophiles of widely differing geographic origins. Included are results from an analysis of the first deep-trench bacterial isolates recovered from the southern hemisphere (9.9-km depth) and of the first gram-positive piezophilic strains. These new data allowed both phylogenetic and structural 16S rRNA comparisons among deep-ocean trench piezophiles and closely related strains not adapted to high pressure. Our results suggest that (i) the Circumpolar Deep Water acts as repository for hyperpiezophiles and drives their dissemination to deep trenches in the Pacific Ocean and (ii) the occurrence of elongated helices in the 16S rRNA genes increases with the extent of adaptation to growth at elevated pressure. These helix changes are believed to improve ribosome function under deep-sea conditions.

Adaptation, Physiological↗
PubMed1997

Background adaptation by Xenopus laevis: a model for studying neuronal information processing in the pituitary pars intermedia.

This review is concerned with recent literature on the neural control of the pituitary pars intermedia of the amphibian Xenopus laevis. This aquatic toad adapts skin colour to the light intensity of its environment, by releasing the proopiomelanocortin (POMC)-derived peptide alpha-MSH (alpha-melanophore-stimulating hormone) from melanotrope cells. The activity of these cells is controlled by brain centers of which the hypothalamic suprachiasmatic and magnocellular nuclei, respectively, inhibit and stimulate both biosynthesis and release of alpha-MSH. The suprachiasmatic nucleus secretes dopamine, GABA, and NPY from synaptic terminals on the melanotropes. The structure of the synapses depends on the adaptation state of the animal. The inhibitory transmitters act via cAMP. Under inhibition conditions, melanotropes actively export cAMP, which might have a first messenger action. The magnocellular nucleus produces CRH and TRH. CRH, acting via cAMP, and TRH stimulate POMC-biosynthesis and POMC-peptide release. ACh is produced by the melanotrope cell and acts in an autoexcitatory feedback on melanotrope M1 muscarinic receptors to activate secretory activity. POMC-peptide secretion is driven by oscillations of the [Ca2+]i, which are initiated by receptor-mediated stimulation of Ca2+ influx via N-type calcium channels. The hypothalamic neurotransmitters and ACh control Ca2+ oscillatory activity. The structural and functional aspects of the various neural and endocrine steps in the regulation of skin colour adaptation by Xenopus reveal a high degree of plasticity, enabling the animal to respond optimally to the external demands for physiological adaptation.

Adaptation, Physiological↗
PubMed2003

Vascular adaptation of intact joint stabilizing structures in the posterior cruciate ligament deficient rabbit knee.

Loss of the posterior cruciate ligament (PCL) of the knee has a significant impact on joint stability and biomechanical function. Changes in joint biomechanics may result in mal-adaptive tissue degeneration and functional alteration of supporting ligaments. This study examines the effects of joint laxity on the vascular physiology of the intact anterior cruciate (ACL) and medial collateral (MCL) ligaments after PCL transection in rabbits.One-year-old female New Zealand white rabbits were assigned to control (n=12), sham-operated (n=12) or PCL transected (2, 6 or 16 weeks, n=12 per time point) groups. Half of the animals (n=6 per group) were used for ACL and MCL blood flow determination using coloured microsphere infusion (ml/min/100 g), and half were used for vascular volume determination (given as vascular index, micro l/g). In the MCL, PCL transection induced large, significant (4-5-fold) increases in blood flow (peak at 2 weeks) and vascular index (peak at 6 weeks) compared to sham-operated animals that returned towards control values by 16 weeks. In contrast, the ACL showed no increase in blood flow in lax joints, and a relatively small (2-fold) increase in vascular index at 6 weeks only. The wet weight and water content of both the MCL and ACL were significantly increased in PCL-deficient joints. We conclude that joint laxity (instability) subsequent to loss of the PCL in rabbits impacts the vascular physiology of intact supporting ligaments, inducing both vasomotor and angiogenic responses in the MCL. Changes in wet weight and water content of both the MCL and ACL demonstrate prolonged physiological adaptation of intact structures in lax joints.

Adaptation, Physiological↗
PubMed2001

Fetal growth restriction: adaptations and consequences.

A range of pathophysiological factors can result in a perturbation or restriction of fetal growth, and the cardiovascular, neuroendocrine and metabolic adaptations of the fetus to these stimuli will depend on their nature, timing and intensity. The critical importance of these physiological adaptations for both immediate survival and long-term health outcomes has provided an impetus for experimental studies of the nature and consequences of specific fetal adaptations to a poor intrauterine environment. This review summarizes data from recent studies that have focused on the responses of the fetal cardiovascular, sympathoadrenal, hypothalamo-pituitary-adrenal and renin-angiotensin systems to experimental restriction of placental function in the sheep and discusses the consequences of these adaptations for fetal, neonatal and adult health.

Adaptation, Physiological↗
PubMed1983

Physical conditioning of children.

Exercise-induced changes in muscular and cardiovascular function in pre- and postpubescent children are explained in terms of a "Trigger Hypothesis." This hypothesis predicts that, prepubertally, there will be only small training-induced biological alterations because of the lack of hormonal control. It is suggested, therefore, that emphasis be placed on skill acquisition rather than physiological conditioning during prepuberty. Postpubertal exercise-induced changes are well documented and follow predictable patterns. The principles that govern physiological adaptations to exercise are discussed in terms of energy transfer and the factors that affect training. Duration, intensity, and frequency of performance are detailed. It is recommended that emphasis be placed on these factors when designing a physiologically sound physical training program.

Adaptation, Physiological↗
PubMed2002

Nonhuman primate transgenesis: progress and prospects.

The nonhuman primate is used extensively in biomedical research owing to its close similarities to human physiology and human disease pathophysiology. Recently, several groups have initiated efforts to genetically manipulate nonhuman primates to address complex questions concerning primate-specific development and physiological adaptation. Primates pose unique challenges to transgenesis and, although this field is still in its infancy, the potential for obtaining new insights into primate physiology and gene function is unprecedented. This review focuses on the methods and potential applications of genetically altered nonhuman primates in biomedical research.

Adaptation, Physiological↗
PubMed2003

Effect of air temperature on forecasting the start of the Betula pollen season at two contrasting sites in the south of Europe (1995-2001).

In order to survive periods of adverse cold climatic conditions, plant requirements are satisfied by means of physiological adaptations to prevent cells from freezing. Thus, the growth of woody plants in temperate regions slows down and they enter into a physiological state called dormancy. In order to identify the chilling and heat requirements to overcome the dormancy period of Betula in the south of Europe, a comparative study was carried out with aerobiological pollen data of a 7-year (1995-2001) period in Vigo (Spain) and Perugia (Italy). To satisfy chilling requirements, base temperatures of 7 degrees C and 5.75 degrees C showed a lower standard variation coefficient: 3.94% and 2.36% in Perugia and Vigo respectively. In the case of heat accumulation, the sum of mean temperatures in Perugia and the sum of maximum temperatures in Vigo were the parameters that showed a minor coefficient of variation (11.13% and 14.51% respectively).

Adaptation, Physiological↗
PubMed2005

Loaded wheel running and muscle adaptation in the mouse.

Voluntary cage wheel exercise has been used extensively to determine the physiological adaptation of cardiac and skeletal muscle in mice. In this study, we tested the effect of different loading conditions on voluntary cage wheel performance and muscle adaptation. Male C57Bl/6 mice were exposed to a cage wheel with no-resistance (NR), low-resistance (LR), or high-resistance (HR) loads for 7 wk. Power output was elevated (3-fold) under increased loading (LR and HR) conditions compared with unloaded (NR) exercise training. Only unloaded (NR) exercise induced an increase in heart mass, whereas only loaded (LR and HR) exercise training induced an increase in skeletal (soleus) muscle mass. Moreover, unloaded and loaded exercise training had a differential impact on the cross-sectional area of muscle fibers, depending on the type of myosin heavy chain expressed by each fiber. The biochemical adaptation of the heart was characterized by a decrease in genes associated with pathological (but not physiological) cardiac hypertrophy and a decrease in calcineurin expression in all exercise groups. In addition, transcriptional activity of myocyte enhancer factor-2 (MEF-2) was significantly decreased in the hearts of the LR group as determined by a MEF-2-dependent transgene driving the expression of beta-galactosidase. Phosphorylation of glycogen synthase kinase-3beta, protein kinase B (Akt), and p70 S6 kinase was increased only in the hearts of the NR group, consistent with the significant increase in cardiac mass. In conclusion, unloaded and loaded cage wheel exercise have a differential impact on cage wheel performance and muscle (cardiac and skeletal) adaptation.

Adaptation, Physiological↗
PubMed2006

Evolutionary diversification of the bean beetle genus Callosobruchus (Coleoptera: Bruchidae): traits associated with stored-product pest status.

Despite the fact that many plant-feeding insects are pests, little effort has been made to identify key evolutionary trait transitions that allow taxa to acquire or lose pest status. A large proportion of species in the genus Callosobruchus are economically important pests of stored, dry postharvest beans of the tribe Phaseoleae. However, the evolution of this feeding habit is poorly understood. Here, we present a reconstruction of the phylogeny of the Asian and African Callosobruchus based on three mitochondrial genes, and assess which traits have been associated with the evolutionary origin or loss of ability to reproduce on dry beans. Our phylogenetic analysis showed that species group into the chinensis and the maculatus clades, which are also supported by genital morphology, and an additional paraphyletic group. Ancestral ability to use dry beans has been lost in the chinensis clade but acquired again in C. chinensis. Dry-bean use and host-plant use were both phylogenetically constrained and transitions in the two were significantly correlated. Host shifts from the subtribe Phaseolinae to Cajaninae were more common than the reverse and were more likely in species using young beans. The ability to use dry beans was more likely gained when using Phaseolinae hosts and promoted habitat shifts from tropical to temperate regions. Adaptation to arid climate was also associated with the ability to reproduce on dry beans and on Phaseolinae. Thus, our analysis suggests that physiological adaptations to an arid climate and to Phaseolinae hosts both render beetles predisposed to become pests of cultivated beans.

Adaptation, Physiological↗
PubMed2002

Muscular adaptations in response to three different resistance-training regimens: specificity of repetition maximum training zones.

Thirty-two untrained men [mean (SD) age 22.5 (5.8) years, height 178.3 (7.2) cm, body mass 77.8 (11.9) kg] participated in an 8-week progressive resistance-training program to investigate the "strength-endurance continuum". Subjects were divided into four groups: a low repetition group (Low Rep, n = 9) performing 3-5 repetitions maximum (RM) for four sets of each exercise with 3 min rest between sets and exercises, an intermediate repetition group (Int Rep, n = 11) performing 9-11 RM for three sets with 2 min rest, a high repetition group (High Rep, n = 7) performing 20-28 RM for two sets with 1 min rest, and a non-exercising control group (Con, n = 5). Three exercises (leg press, squat, and knee extension) were performed 2 days/week for the first 4 weeks and 3 days/week for the final 4 weeks. Maximal strength [one repetition maximum, 1RM), local muscular endurance (maximal number of repetitions performed with 60% of 1RM), and various cardiorespiratory parameters (e.g., maximum oxygen consumption, pulmonary ventilation, maximal aerobic power, time to exhaustion) were assessed at the beginning and end of the study. In addition, pre- and post-training muscle biopsy samples were analyzed for fiber-type composition, cross-sectional area, myosin heavy chain (MHC) content, and capillarization. Maximal strength improved significantly more for the Low Rep group compared to the other training groups, and the maximal number of repetitions at 60% 1RM improved the most for the High Rep group. In addition, maximal aerobic power and time to exhaustion significantly increased at the end of the study for only the High Rep group. All three major fiber types (types I, IIA, and IIB) hypertrophied for the Low Rep and Int Rep groups, whereas no significant increases were demonstrated for either the High Rep or Con groups. However, the percentage of type IIB fibers decreased, with a concomitant increase in IIAB fibers for all three resistance-trained groups. These fiber-type conversions were supported by a significant decrease in MHCIIb accompanied by a significant increase in MHCIIa. No significant changes in fiber-type composition were found in the control samples. Although all three training regimens resulted in similar fiber-type transformations (IIB to IIA), the low to intermediate repetition resistance-training programs induced a greater hypertrophic effect compared to the high repetition regimen. The High Rep group, however, appeared better adapted for submaximal, prolonged contractions, with significant increases after training in aerobic power and time to exhaustion. Thus, low and intermediate RM training appears to induce similar muscular adaptations, at least after short-term training in previously untrained subjects. Overall, however, these data demonstrate that both physical performance and the associated physiological adaptations are linked to the intensity and number of repetitions performed, and thus lend support to the "strength-endurance continuum".

Adaptation, Physiological↗
PubMed1997

Evolutionary physiology: history, principles.

1) The history of comparative and evolutionary physiology since the early XIX century is given; 2) The methods of evolutionary physiology are described; 3) Principles of the evolution of function are discussed at every level of physiological organization (cellular, functional units of the organ, the organ itself, functional systems) as they apply to the kidney and to the regulation of salt and water balance; and 4) General questions of evolutionary physiology covering physico-chemical factors in evolution of functions, the development of the integrity of an organism, the origin of physiological adaptation, the development of interconnection of physiological systems are discussed.

Animals↗
PubMed1987

Neurovisual adaptations to subnormal vision in children.

Neurovisual adaptations to subnormal vision in children are of practical importance and need to be remembered in the management of children with low vision. The physiological adaptations discussed include shortening the focal distance, abnormal head positions, compensatory head movements, and ocular motor search strategies. In addition the concept of neural plasticity, particularly in respect to the ability of the extrageniculate striaete system to assume primary visual function in cortically damaged children is discussed.

Accommodation, Ocular↗
PubMed2000

Calcium in pregnancy and lactation.

Pregnancy and lactation are periods of high calcium requirement. This review highlights recent advances in our understanding of calcium and bone metabolism during human pregnancy and lactation and discusses the findings in relation to the calcium nutrition of the mother. The evidence indicates that pregnancy and lactation are characterized by physiological adaptive processes that are independent of maternal calcium intake and that provide the calcium necessary for fetal growth and breast-milk production without requiring an increase in maternal calcium intake. There are firm data that demonstrate that a low calcium intake during lactation does not lead to impaired lactational performance or to exaggerated bone loss. However, more research is required to define whether a low calcium intake prior to or during pregnancy can have deleterious effects on reproductive and lactational performance, and on the long-term health of the mother and child.

Adaptation, Biological↗