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PubMed2006

How to bite your tongue without blowing your top: implicit evaluation of emotion regulation predicts affective responding to anger provocation.

People frequently have to control their emotions to function in life. However, mounting evidence suggests that deliberate emotion regulation often is costly. This presents a dilemma: Is it better to let emotions go or to pay the price of exerting costly control? In two studies, the authors explore whether emotion regulatory processes associated with implicit positive evaluation of emotion regulation might provide the benefits of successful emotion regulation without the costs. In Study 1, the authors introduce a measure of implicit evaluation of emotion regulation (ER-IAT). Study 2 examined whether this measure is associated with actual emotional responses to an anger provocation. It was found that greater ER-IAT scores were associated with lesser anger experience, fewer negative thoughts, lessened self-reported effortful emotion regulation, and an adaptive pattern of cardiovascular responding. These findings suggest that implicit positive evaluation of emotion regulation is associated with successful, automatic, and physiologically adaptive down-regulation of anger.

Adaptation, Psychological↗
PubMed1992

[Value of an algorithm of automatic adaptation of the atrio-ventricular delay to the instantaneous atrial rate in cardiac stimulation].

It has been suggested that an algorithm of automatic adaptation of the AV delay to the instantaneous atrial rate be introduced into the program of DDD pacemakers to reproduce the physiological adaptation of the PR interval to effort, characterised by progressive shortening inversely linearly related to the heart rate. In order to evaluate the potential benefits in conditions of "standard" programming (basal AV delay the same for all patients: maximal frequency of 1/1 AV synchronisation uniformly limited to 120 bpm), a haemodynamic study was undertaken in 10 patients who had permanent DDD pacemakers implanted for advanced AV block. Measurements were taken during two standardized exercise stress tests (20 W/2 mn steps from an initial load of 20 W) performed in a random order, one with a fixed AV delay of 156 ms and the other with an "automatic AV delay" allowing linear reduction from a maximum value of 156 ms at rest to a minimum value of 84 ms at the maximum heart rate of 120 bpm. At the peak of exercise the "automatic AV delay" significantly affected 4 parameters: the paced ventricular rate (p = 0.008) and rate-pressure product (p = 0.005) which increased, pulmonary capillary pressure (p = 0.03) and cycle-to-cycle variability of systolic and diastolic blood pressures (p = 0.02 < p < 0.0001) which decreased. There was a tendency (NS) to slowing of the spontaneous atrial rate and to increase in cardiac output. This increase was significant in some patients and seemed to be due to a good relationship between the individual optimal value of the value basal AV delay measured by Doppler echocardiography and the value programmed in this study (156 ms).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1996

A measurement model of cortisol reactivity of healthy older adults.

Research on the physiological adaptation process has found that stress is associated with the rate of cortisol secretion, the main hormone that reflects stress. However, considerable variation among subjects has been reported. Using a sample of older adults (N=46), we tested the hypothesis that cortisol reactivity is composed of (1) a situation-related component representing hypothalamic influence on cortisol secretion observed on three different occasions, and (2) a stable component representing a general trait responsible for cortisol responses observed from occasion to occasion. LISREL VIII was used to test this hypothesis. Results indicated that a homogeneous reliability model was not supported by the data. A congeneric measurement model represented a better fit to the data. Results suggest that subjects have consistent patterns of response during separate experimental occasions. However, results do not suggest a consistent pattern of response over time. The main implication of these results is that salivary cortisol measures are sensitive to experimental stress situations. As such, this noninvasive method may be useful in examining adaptive responses to stress.

Adaptation, Psychological↗
PubMed1990

Value of physiological measurement in sport.

The value of physiological measurement in sport lies in the opportunity it provides to learn more about the responses of individuals to the demands of exercise, the particular physiological characteristics which allow some individuals to become successful at some sports, but not others, and the physiological adaptations to training which underlie improvements in human performance. In this paper, running has been used to illustrate the value of making physiological measurements on sportsmen and women because it is an activity which is common to many sports. Sports can be divided into two broad groups, namely the 'endurance sports' and, what may be called, the 'multiple sprint' sports. The focus of attention of this brief overview is the physiological measurements which provide a general description of the 'fitness' for these sports.

Anaerobic Threshold↗
PubMed1992

[The physiological mechanisms of the adaptation of metal workers to exposure to elevated convection and combined radiant and convection heat].

Metallurgists exposed to exceeding amounts of radiant heat and convection heat combined with the radiant one demonstrate such general physiologic adaptational mechanisms as: reflectory tachycardia, intensive sweating, heat conducting to the skin surface of the body, abruptly increased minute respiratory volume and possible filtrative sweating. Furthermore heavy physical work induced the extremely abrupt tachycardia, the increased systolic and pulse pressure, systolic and cardiac output, total ventilation per minute. The recommendations were suggested to prevent overheating in workers.

Adaptation, Physiological↗
PubMed1989

Kappa Delta Award paper. Tissue fluid pressures: from basic research tools to clinical applications.

The two basic research tools developed to measure tissue fluid pressure (wick catheter) and osmotic pressure (colloid osmometer) have undergone extensive validation and refinement over the past 20 years. Using these techniques, basic science investigations were undertaken of edema in Amazon reptiles, pressure-volume relations in animals and plants, adaptive physiology of Antarctic penguins and fishes, edema in spawning salmon, tissue fluid balance in humans under normal conditions and during simulated weightlessness, and orthostatic adaptation in a mammal with high and variable blood pressures--the giraffe. Following and sometimes paralleling this basic research have been several clinical applications related to use of our colloid osmometer and wick technique. Applications of the osmometer have included insights into (a) reduced osmotic pressure of sickle-cell hemoglobin with deoxygenation and (b) reduced swelling pressure of human nucleus pulposus with hydration or certain enzymes. Clinical uses of the wick technique have included (a) improvement of diagnosis and treatment of acute and chronic compartment syndromes, (b) elucidation of tissue pressure thresholds for neuromuscular dysfunction, and (c) development of a better tourniquet design for orthopaedics. This article demonstrates that basic research tools open up areas of basic, applied, and clinical research.

Animals↗
PubMed2002

Scientific contributions of A. V. Hill: exercise physiology pioneer.

Beginning in 1910, A. V. Hill performed careful experiments on the time course of heat production in isolated frog muscle. His research paralleled that of the German biochemist Otto Meyerhof, who measured the changes in muscle glycogen and lactate during contractions and recovery. For their work in discovering the distinction between aerobic and anaerobic metabolism, Hill and Meyerhof were jointly awarded the 1922 Nobel Prize for Physiology or Medicine. Because of Hill's interest in athletics, he sought to apply the concepts discovered in isolated frog muscle to the exercising human. Hill and his colleagues made measurements of O(2) consumption on themselves and other subjects running around an 85-m grass track. In the process of this work, they defined the terms "maximum O(2) intake," "O(2) requirement," and "steady state of exercise." Other contributions of Hill include his discoveries of heat production in nerve, the series elastic component, and the force-velocity equation in muscle. Around the time of World War II, Hill was a leading figure in the Academic Assistance Council, which helped Jewish scientists fleeing Nazi Germany to relocate in the West. He served as a member of the British Parliament from 1940 to 1945 and as a scientific advisor to India. Hill's vision and enthusiasm attracted many scientists to the field of exercise physiology, and he pointed the way toward many of the physiological adaptations that occur with physical training.

Animals↗
PubMed1996

[Complex biomedical studies of the body under conditions of extreme marine factors].

The results of experiments with 50 volunteers are presented, exposed to conditions, similar to those of ship-wreck-on rafts and boats anchored in the sea and with restricted taking of food and water. Complex medical studies have been accomplished. The state of the cardio-vascular, nerve, respiratory and sensor systems and the metabolism of certain substances are followed up. The electrophysiological studies include: EKG, EEG, ENG, SPO, ZPO, SSEP, craniocorpography, computer analysis of the cardiac variability. A part of these have been monitored during the whole experiment using Holter records or by cable and telemetric way in special laboratories on the beach. The biochemical studies include indicators characterizing the metabolism of carbohydrates, lipids, proteins, mineral-electrolytes and biogenic amines. Some individual features in the course of sea-sickness are described according to the phenotype and the genotype characteristics of the adaptation processes. Special attention is paid to vestibular-vegetative, neurologic and psychic changes as well as on the manifestations of orthostatic collapse, sometimes ending by loss of consciousness or epi-fainting. It is considered that the orthostatic collapse is due to the combined influence of prolonged vestibular overstrain, hypokinesia, starvation, thirst and psycho-emotional stress. This is the possible main cause for the death of some saved ship-wreckers. An actualization of the instruction for saving of ship-wreckers is recommended with including of a special movement regime in the saving devices. Sibellium (flunarizin) is offered as a prophylactic and therapeutic agent against sea-sickness.

Accidents↗
PubMed1998

Spatial heterogeneity and insect adaptation to toxins.

Behavioral responses of insect herbivores to toxins are examined in managed and natural systems with reference to two important but largely ignored factors: heterogeneity in toxin distributions and the nature of the relationship between behavioral responses and physiological adaptation to the same toxins. Heterogeneous toxin distributions, which provide the opportunity for behavioral responses, are ubiquitous in managed and natural systems. Insect herbivores have evolved a wide variety of behavioral responses to such toxins. The nature of behavioral responses reflects toxin apparency, mode of action, and the extent to which sublethal effects influence behavior. The interaction between these behavioral responses to heterogeneously distributed toxins and physiological mechanisms of tolerance has influenced the evolution of insecticide resistance in managed systems and the evolution of plant defensive strategies in natural systems. An understanding of this interaction could lead to more evolutionarily stable methods of crop protection.

Journal Article↗
PubMed2002

Induction of cellular oxidative stress by aryl hydrocarbon receptor activation.

The aryl hydrocarbon receptor (AHR) has long been associated with the induction of a battery of genes involved in the metabolism of foreign and endogenous compounds. Depending on experimental conditions, AHR can mediate either activation or amelioration of chemical toxicity. For the past decade, evidence has mounted that AHR is associated with a cellular oxidative stress response that must be considered when evaluating the mechanism of action of xenobiotics capable of activating AHR, or capable of metabolic activation by enzymes encoded by genes under control of AHR. In this review, we have evaluated the diverse mechanisms by which AHR generates an oxidative stress response, including inflammation, antioxidant and prooxidant enzymes and cytochrome P450. A review of the regulation of Ahr transcription and functional polymorphisms especially related to oxidative stress is also included. We have carefully avoided placing a value judgment on the degree of toxicity produced by such a response, in view of the realization that an oxidative response is involved in many normal physiological processes. Since the interface between physiological, adaptive and toxicological responses elicited by the AHR-mediated oxidative stress response is not clearly defined, it behooves the researcher to evaluate both toxicological and physiological features of the response.

Animals↗
PubMed2005

Lactate threshold responses to a season of professional British youth soccer.

OBJECTIVE: To examine the changes in aerobic endurance performance of professional youth soccer players throughout the soccer season. METHODS: Nine youth soccer players were tested at six different time points throughout the soccer season by sub-maximal blood lactate assessment, using an incremental treadmill protocol. Whole blood lactate concentration and heart frequency (Hf) were determined at each exercise stage. Running velocities at the first lactate inflection point (v-T(lac)) and at a blood lactate concentration of 4 mmol l(-1) (v-4mM) were determined. RESULTS: Running velocity at the two lactate thresholds increased from the start of pre-season training to the early weeks of the competitive season, from 11.67 (0.29) to 12.96 (0.28) km h(-1) for v-T(lac), and from 13.62 (0.25) to 14.67 (0.24) km h(-1) for v-4mM (p<0.001). However, v-T(lac )and v-4mM when expressed relative to maximum heart frequency (Hf(max)) remained unchanged. The Hf to blood lactate concentration relationship was unchanged after the pre-season training period. The two expressions of lactate threshold did not reveal differences between each other. CONCLUSION: Running velocity at v-T(lac )and v-4mM increased significantly over the pre-season period, but v-T(lac )and v-4mM were unchanged when expressed relative to Hf(max). This finding may indicate that increased endurance performance may be mainly attributable to alterations in Vo(2max). Although lactate assessment of soccer players is useful for determining endurance training adaptations in soccer players, additional assessment of the other two determinants of endurance performance (Vo(2max) and running economy) may provide more useful information for determining physiological adaptations resulting from soccer training and training interventions.

Adolescent↗
PubMed1993

Effects of corticosteroids in preterm sheep on adaptation and sympathoadrenal mechanisms at birth.

This study investigates the effects of prenatal corticosteroid administration on newborn sympathoadrenal mechanisms involved in postnatal adaptation. Randomly assigned preterm (122-125 days) fetal sheep were treated with hydrocortisone or saline for 60 h and delivered by cesarean section. We examined postnatal physiological adaptation, sympathoadrenal responses, cardiac beta-receptor density, and the receptor-cyclase system. We observed increased ventilatory, cardiovascular, and metabolic responses function in the corticosteroid-treated animals despite a marked attenuation in the anticipated surge of plasma catecholamine concentrations and a decrease in epinephrine secretion rate, which is normally seen at birth. Myocardial beta-adrenergic receptor density and affinity states were comparable in both groups. Basal and agonist-mediated adenylyl cyclase activity in myocardial tissue was increased in the corticosteroid-treated animals. We speculate that the increase in myocardial adenylyl cyclase activity may be accompanied by similar changes in other organ systems and that this could account for the augmentation in respiratory, cardiovascular, and metabolic responses in the corticosteroid-treated animals.

Acclimatization↗
PubMed1991

Detection of growth-stimulating activity in the proximal small intestine during weaning in the suckling rat.

Adaptive changes in enzyme expression and cell proliferation occur in the small intestine of the suckling rat at the beginning of the 3rd postnatal week. This physiological adaptation can be modulated by factors including diet or glucocorticoids. We have previously described an intestinal growth-stimulating fraction derived from the remnant small bowel after resection and found that enteral nutrition is critical for its detection. In view of the similarity between the changes in cell proliferation that occur between 15 and 22 days postnatally and those immediately after resection, we sought to determine whether the small intestinal mucosa of the neonatal rat also contains a similar growth-stimulating fraction. Our results show that extracts of the proximal intestine prepared from 15-day-old rats do contain the growth-stimulating fraction. The activity was not detectable in maternal milk nor in the intestinal extract from 8-day-old rats. When the suckling rats were deprived of solid food, the activity was not detectable in the 15-day-old group. Gel filtration of the acidic extract on a G-25 Sephadex column revealed that the active component is made up of two molecular weight species (approximately 4,500 and 1,500 daltons) similar to that described in the proximal intestine of the postresectional model. These findings suggest that dietary factors may play a role in modulating the proliferative changes that occur at the time of weaning by way of the growth-stimulating fraction.

Aging↗
PubMed2000

Microdiversity of Culturable Diazotrophs from the Rhizoplanes of the Salt Marsh Grasses Spartina alterniflora and Juncus roemerianus.

Salt marshes dominated by Spartina alterniflora (smooth cordgrass) are among the most productive ecosystems known, despite nitrogen limitation. Rhizoplane/rhizosphere diazotrophy (nitrogen fixation) serves as a significant source of combined nitrogen in these systems. Several recent studies have demonstrated remarkable physiological and phylogenetic macro- and microdiversity within this important functional group of organisms. However, the ecological significance of this diversity is presently unknown. The physiological characteristics of the culturable, oxygen-utilizing fraction of the rhizoplane diazotroph assemblages from Spartina alterniflora and from another salt marsh grass, the black needle rush Juncus roemerianus, were examined in combination with an assessment of the phylogenetic relatedness by whole genome DNA-DNA hybridization. Analysis of substrate utilization data permitted quantitative evaluation of fully cross-hybridizing strain groups and physiological clusters. Phylogenetically related strains, defined by DNA homology >/=90% relative to the positive control, displayed extensive physiological diversity. Seven bootstrap-supported physiological clusters, composed largely of phylogenetically dissimilar strains, showed similar utilization patterns for at least one class of ecologically relevant substrates (carbohydrates, carboxylic acids, or amino acids). These diazotrophs appear to be physiologically adapted for utilization of specific substrates or classes of substrates, lending support to diazotrophic functional redundancy. Microenvironmental heterogeneity is credited for promoting this diversity by selecting for physiologically specialized diazotroph populations to occupy defined niches in situ. One outcome of this physiological diversity is maintenance of a crucial environmental function (nitrogen fixation) over a broad range of environmental conditions.

Journal Article↗
PubMed2001

Physiological variation in insects: hierarchical levels and implications.

Variation, and in particular regular pattern in that variation, forms the foundation for evolutionary physiology. Nonetheless, with the exception of seemingly good fits between the tolerances of animals and the environments they live in, this variation is often not well explored. Here, three examples of different forms of such variation (both large- and small-scale) in a range of physiological traits in insects are explored. In the first example, I show that at global, regional, and local scales, variation in insect upper lethal temperatures is far less variable than variation in lower lethal temperatures, and that upper and lower tolerances are partially decoupled. Second, I demonstrate that variation in upper and lower lethal limits, desiccation resistance and tolerance, and respiration rate are often partitioned at taxonomic levels above that of the species. In other words, there is considerable phylogenetic constraint in the evolution of the responses of insects to the environment. These findings suggest that several ideas regarding insect physiological adaptations might have to be re-examined. They also suggest that approaches using both "raw" and corrected data should be adopted where possible. Finally, I demonstrate that there is considerable intra-individual variation in the characteristics of insect discontinuous gas exchange cycles. This is perhaps well-known to researchers in the field, but the implications thereof for arguments in favour of the adaptive nature of these regular cycles have not been carefully examined. Together, these findings suggest that there is still much to be learned about variation in insect physiological traits.

Journal Article↗