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At least 973 records · Page 54Linked to original sources
PubMed1994

Changes in hypothalamic [correction of hypothalmic] staining for c-Fos following 2G exposure in rats.

The static gravitational field of the earth has been an important selective pressure that has shaped the evolution of biological organisms. This is illustrated by the evolution of tetrapods from a water environment where gravitational force was partially negated to a terrestrial environment where gravity is of greater consequence. Terrestrial invasion resulted in a series of new structural, physiological, and behavioral features. Therefore, it is not surprising that alterations in the gravitational field can cause widespread effects in many physiological systems and behaviors. Our previous studies have demonstrated that both exposure to hyperdynamic fields and the microgravity condition of space flight have significant effects on body temperature, heartrate, activity, feeding, drinking, and circadian rhythms. However, it has not been determined whether these physiological adaptations are associated with changes in neural activity within the hypothalamic nuclei that regulate these functions. This study examined the changes in body temperature, activity, body weight and food and water intake in rats caused by exposure to a hyperdynamic field. In addition, the immediate early gene activation marker, c-Fos, was used to examine potential protein synthesis changes in the hypothalamic nuclei that regulate these functions.

Animals↗
PubMed2004

[Soluble sugar content of clonal plant Neosinocalamus affinis at module and ramet levels].

In this paper, soluble sugar content of Neosinocalamus affinis was measured by anthrone colorimetry at two levels of module and ramet in order to reveal its ecological and physiological adaptability. The results showed that soluble sugar content decreased in the order of leaf > branch > culm. As for soluble sugar content, different modules responded to ramet age and position in different ways. The branch and culm of 1-year-old ramets contented more soluble sugar than those of other four ages, but soluble sugar content in leaf was independent to ramet age. For leaf and culm, lower parts of ramet contented more soluble sugar than middle and upper parts. Under high irradiance, the soluble sugar content of Neosinocalamus affinis leaf was more than that under low irradiance. Seasonal change had significant effect on soluble sugar content. The soluble sugar content of leaf presented a monthly change, with a bottom and upper value in January and in April, respectively, but there was no obvious difference between 2-year-old and 3-year-old ramets. The soluble sugar content of parent ramet leaves was positively correlative to that of daughter ramet in upper and middle parts of ramets. There was no significant difference between ramet ages at ramet level. Hierarchical response of physiological character to environmental changes existed at the module and ramet levels of Neosinocalamus affinis.

Glucose↗
PubMed1986

Ouabain binding sites and (Na+,K+)-ATPase activity in rat cardiac hypertrophy. Expression of the neonatal forms.

The adaptation of the myocardium to mechanical overload which results in cardiac hypertrophy involves several membrane functions. The digitalis receptor in sarcolemma vesicles from hypertrophied rat hearts is characterized by binding of [3H]ouabain and ouabain-induced inhibition of (Na+,K+)-ATPase. The results show the existence of two families of ouabain binding sites with apparent dissociation constants (Kd) of 1.8-3.2 X 10(-8) M and 1-8 X 10(-6) M, respectively, which are similar to those found in normal hearts. The presence of the high affinity receptor in hypertrophied rat heart is correlated to a detectable inhibition of the (Na+,K+)-ATPase (IC50 = 1-3 X 10(-8) M). However, the high and low affinity sites in hypertrophied hearts bind and release ouabain at 4-5-fold slower rates than the corresponding sites in normal hearts. These properties are similar to that we observed in newborn rat cardiac preparations. Taken together with the expression of myosin isoforms (Schwartz, K., Lompre, A.M., Bouveret, P., Wisnewsky, C., and Whalen, R.G. (1982) J. Biol. Chem. 23, 14412-14418), our data show that the physiological adaptation of the heart also involves the resurgence of the neonatal forms of the digitalis receptor.

Animals↗
PubMed1995

Gender-, side- and site-dependent variations in human perioral spatial resolution.

Twenty-eight right-handed, young adults participated in a sensory testing experiment to evaluate spatial resolution at 10 positionally matched sites on the right- and left-hand sides of the face. An adaptive psychophysical (i.e. tracking) procedure was used to estimate the threshold spatial separation for perceiving two points of contact at each site. Estimates of the threshold at one site on both sides of the face were also obtained with a method-of-limits procedure similar to that employed for clinical evaluation of patients. In addition, each individual was asked to rate (i) his(her) overall facial sensitivity to touch and (ii) the degree to which he(she) could discern subtle changes in lip, cheek and chin position during speech, chewing and facial expression. Analysis of the estimates of the threshold separation obtained with the tracking procedure revealed a significant effect of gender (p < 0.04) and of site (p < 0.001). Females were more spatially sensitive than males: average threshold separations were 1.55 mm less. Most notably, the threshold increased ninefold with distance posterolaterally from the oral opening. The vermilion of the upper lip was the most spatially sensitive site (population geometric mean = 2.4 mm) and the preauricular skin the least spatially sensitive site (20.9 mm). Significant effects of side and of interactions among gender, side and site were not observed. The estimates obtained with the method-of-limits procedure were very similar to those obtained with the tracking procedure: the latter were 0.67 mm less on the average. Individuals' ratings of overall facial sensitivity to touch were similar for males and females (p > 0.70). Females, however, reported greater ability to discern subtle changes in lip, cheek and chin position than males (p < 0.03). The ratings of this sensory function correlated negatively with the estimates of the threshold separation on the vermilion of the upper lip (p < 0.03).

Adaptation, Physiological↗
PubMed1986

The ultrastructure and physiology of the tergotrochanteral depressor muscle of the housefly, Musca domestica.

The gross morphology, ultrastructure, and the physiological properties of the tergotrochanteral depressor muscle (TTM) of the housefly are described. Under transmission and scanning electron microscopy, the TTM is a highly modified multinucleated tubular muscle of the synchronous class of insect muscle. Mitochondria appear few in number (5% of muscle volume) but there is an extensive sarcoplasmic reticulum (20% of muscle volume). Two types of neuromuscular junctions were observed, but these junctions are considered functionally similar. Three neurons innervate the muscle, and when the muscle is orthodromically stimulated, three well-defined thresholds are observed. Under repeated stimulation, the TTM fatigues rapidly but recovers in a short time. The TTM has a long "length constant" of 132.1 micron, 7.3 microF/cm2 membrane capacity, and a specific resistance of 394 omega cm2. The tergotrochanteral or "jumping" muscle has a behaviorally unique function. It is used only in the jump response preparatory to flight. TTM development is believed to have coevolved with an associated giant neuron to optimize the escape behavior response (response time 2.5 msec) in the housefly. The muscle has become specialized and more massive to increase the jump response. The TTM appears to be adapted physiologically and ultrastructurally for fast response and short twitch duration times.

Animals↗
PubMed2004

Serum carboxyl-terminal propeptide of procollagen type I in exercise-induced left ventricular hypertrophy.

BACKGROUND: Left ventricular hypertrophy (LVH) induced by exercise is considered to be a physiologic adaptive mechanism without fibrogenic hyperactivity, as occurs in pathologic hypertrophy. HYPOTHESIS: This study investigated serum markers of collagen synthesis and echo parameters of left ventricular diastolic function (LVdf) in 22 male athletes. METHODS: Twenty-two highly competitive male athletes (10 cyclists, 12 soccer players) were studied with full history, clinical examination, Doppler echocardiogram, and serum concentration of the carboxyl-terminal propeptide of collagen type I (PIP). They were divided into two groups: normal left ventricular mass (N) with left ventricular mass index (LVMI) < 125 g/m2 (14 athletes) and LVH with LVMI > 125 g/m2 (8 athletes). RESULTS: Age, body surface area, blood pressure, heart rate, and systolic function were not different between the groups. Serum concentration of PIP (N: 163 +/- 44.1 microg/l, LVH: 172.7 +/- 61.2 microg/l--NS) and LVdf (early to atrial peak mitral flow velocity ratio: [E/A] N: 1.77 +/- 0.47, LVH: 1.98 +/- 0.70--NS, and early to atrial peak mitral annulus velocity ratio: [Ea/Aa] N: 2.63 +/- 0.70, LVMI: 2.55 +/- 0.90 LV 1.61--NS) were similar in both groups. CONCLUSIONS: Normal serum concentration of PIP in athletes with LVH in association with normal LVdf indicates the possibility that in this type of physiologic hypertrophy there is mainly an increase of myocyte size without interstitial fibrosis.

Adolescent↗
PubMed1979

Population changes induced in Candida albicans by nalidixic acid.

Cells of Candida albicans plated on media containing nalidixic acid (Nal) either die, adapt physiologically to Nal-tolerance or mutate ot Nal-resistance. The fraction of a population exhibiting each response depends on the growth phase of cells when plated and their nitrogen and carbon nutrition and growth temperatures before and after plating. Nal induces Nal-resistant mutants in very high frequency but only at 37 C on plates containing i) glucose as primary carbon source and ii) adenine, a sulfur amino acid or a representative of the glutamic acid family of amino acids. Nal does not affect either forward mutation to caffeine-resistance or reverse mutation from histidine auxotrophy to prototrophy. Nal-resistant mutants produce minute colonies on N-ALfree medium, respire oxidatively and are unusually sensitive to inhibitors of oxidative phosphorylation. They revert spontaneously to wild type at very high rates but can be propagated indefinitely in the absence of Nal by serial selection and replating of minute colonies. Cellular inactivation and induction of Nal-resistant mutants are greatly affected by specific inhibitors of mitochondrial macromolecular syntheses. The presence of chloramphenicol or erythromycin during exposure to Nal prevents cell death and mutation but has no effect on adaptation to Nal-tolerance. Growth on acriflavin or ethidium bromide enhances resistance of cells to inactivation when subsequently plated on Nal containing media. It is concluded that Nal-induced cellular inactivation and mutation to Nal-resistance, but not adaptation to Nal-tolerance, result from damages to the mitochondrion which are fixed or promoted by macromolecular syntheses within the mitochondrion. Implications of these findings for the therapeutic use of Nal are discussed.

Azides↗
PubMed1994

Human cardiovascular response to sympathomimetic agents during head-down bed rest: the effect of dietary sodium.

Changes in sympathoadrenal function and cardiovascular deconditioning have long been recognized as a feature of the physiological adaptation to microgravity. The deconditioning process, coupled with altered hydration status, is thought to significantly contribute to orthostatic intolerance upon return to Earth gravity. The cardiovascular response to stimulation by sympathomimetic agents before, during, and after exposure to simulated microgravity was determined in healthy volunteers equilibrated on normal or high sodium diets in order to further the understanding of the deconditioning process.

Adult↗
PubMedDate not supplied

Use of aortic valvo-pumps placed in valve annulus for long-term left ventricular assist.

To provide better anatomical fit and physiologic adaptation, three aortic valvo-pumps with different dimensions were developed. Each pump has a rotor with an impeller and drive magnets and a stator consisting of a motor coil with iron core and an outflow guide vane. The devices had outer diameters of 21 mm, 23 mm, and 25 mm, respectively, and weighted 27 g, 31 g, and 40 g, respectively. Laboratory testing demonstrated that the rotating speed for maintaining a diastolic pressure of 80 mm Hg at zero flow rate should be 17500 rpm, 15000 rpm, and 12500 rpm, respectively; the largest flow at these same speeds will be 5 l/min, 7 l/min, and 10 l/min, respectively, with approximately 50 mm Hg pressure head increase. Therefore, these three pumps may meet the hemodynamic requirements of patients with body weights of 40-60 kg, 60-80 kg, and 80-100 kg. The first in vivo trial exhibited that the 25 mm valvo-pump can be sewn onto the aortic valve annulus of a 80 kg body weight pig without harm to adjacent organ functions. The devices occupy no additional anatomic space and deliver the blood directly from ventricle to the aorta, thus producing less physiologic disturbance to the natural circulation. Neither connecting conduits nor bypass circuits are necessary, thus eliminating the most dangerous sites of thrombosis in traditional left ventricular assist devices.

Animals↗
PubMed1995

Plethysmography with optoelectronic sensors: comparison with mercury strain gauge plethysmography.

The study and follow-up of certain physiological adaptations in microgravity, particularly vascular and venous ones, require the use of reliable equipment that yields results well correlated with data provided by equipment usually used in clinical examinations. The purpose of the present study was to evaluate the reproducibility of results obtained using a new type of plethysmography, plethysmography with optoelectronic sensors or volometry, and to verify whether these results correlate with those yielded by mercury strain gauge plethysmography. The plethysmograph is a device which permits measuring limb volume by means of an infra-red light transmitter-receiver system that calculates cross-sectional areas at 220 successive points of a given limb segment. Calf venous capacity (calf volume measured after 50 mm Hg venous occlusion in the thigh) was measured on 27 subjects using volometry and mercury strain gauge plethysmography used as reference method. Results showed a good correlation (r = 0.8, p < 0.001) and a statistically identical reproducibility between the two methods even though venous capacity measurements obtained using these two techniques were not superimposable because they did not use the same model for limb volume measurements. Volometry therefore appears to be a technique of interest for the future, to monitor vascular and muscular physiological parameters in astronauts during long-term microgravity exposure.

Adult↗
PubMed2004

Stress, stress response, and health.

Components of stress and the stress response differ between men and women. The tend-and-befriend response, mediated by oxytocin and endogenous opioids, may be more applicable to women than the fight-or-flight response, which was based largely on studies of men. Even within the flight-or-flight response pattern there are sex-based differences. The HPA axis interacts with reproductive function, such as menstruation. For immune function there are sex differences as well as differences within the menstrual phase. Inclusion of men and women in stress response studies is critical. Further study is needed to clarify the influence of ovarian hormones on the stress and immune responses during the reproductive stages in women's lives, including menarche. pregnancy, and perimenopause.

Adaptation, Physiological↗
PubMed2006

Approaching the shared biology of obesity and depression: the stress axis as the locus of gene-environment interactions.

Obesity and depression are serious public health problems and also constitute cardiovascular disease risk factors. Research organizations have called for efforts to explore the interrelationship between obesity and depression. A useful starting point is the fact that in both disorders there is dysregulation of stress systems. We review molecular and clinical evidence indicating that the mediators of the stress response are a key locus for gene-environment interactions in the shared biology of depression and obesity. Scientific milestones include translational paradigms such as mice knockouts, imaging and pharmacogenomic approaches that can identify new therapeutic strategies for those burdened by these two afflictions of contemporary civilization. Perspectives for the future are promising. Our ability to dissect the underpinnings of common and complex diseases with shared substrates will be greatly enhanced by the Genes and Environment Initiative, the emerging Large Scale Studies of Genes and Environment in Common Disease, and the UK Biobank Project.

Adaptation, Physiological↗
PubMed1998

Skeletal muscle metabolic characteristics before and after energy restriction in human obesity: fibre type, enzymatic beta-oxidative capacity and fatty acid-binding protein content.

BACKGROUND: Skeletal muscle has the ability to adapt as result of dietary, hormonal or pharmacological interventions affecting energy metabolism. The aim of the present study was to investigate the effects of energy restriction on skeletal muscle metabolic characteristics in obese women. METHODS: The effects of 8 weeks' energy restriction on body composition, energy expenditure and skeletal muscle characteristics were investigated in 28 healthy obese women. Subjects were aged 37.9 +/- 1.5 years and had a body mass index of 32.0 +/- 0.8 kg m-2. RESULTS: Energy restriction (2800 kJ day-1) resulted in a 10.8 +/- 0.5 kg weight loss consisting of 8. 6 +/- 0.5 kg of fat mass and 2.2 +/- 0.3 kg of fat-free mass. Basal respiratory exchange ratio, sleeping metabolic rate and exercise-induced thermogenesis significantly declined in response to the diet. These changes were accompanied by an increase (P = 0.038) in the skeletal muscle content of cytosolic fatty acid-binding protein (H-FABP), whereas no changes occurred in fibre type distribution or activities of enzymes reflecting beta-oxidation and mitochondrial density (3-hydroxyacyl-CoA dehydrogenase and citrate synthase respectively). CONCLUSION: The results suggest that increased capacity of intracellular fatty acid transport in skeletal muscle cells is involved in the physiological adaptations of fat metabolism to energy restriction in obese female subjects.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMedDate not supplied

Homologous regulation of melanocortin-1 receptor (MC1R) expression in melanoma tumor cells in vivo.

As G protein-coupled receptors (GPCRs) are the target of numerous signaling molecules, including about half of the therapeutic drugs currently used, it is important to understand the consequences of homologous (ligand-induced) receptor regulation. Continuous exposure of GPCRs to agonist in vitro most frequently results in receptor down-regulation, but receptor up-regulation may occur as well. These phenomena are expected to play a role in the physiological adaptation to endogenous ligands and also in the response to repetitive administration of drugs in the clinic. However, there is little information on homologous regulation of GPCRs in vivo. Here, we report on the regulation of melanocortin-1 receptor (MC1R) expression in melanoma cells implanted into mice. Two melanoma cell lines were investigated, D10 and B16F1, which in vitro had previously been shown to undergo homologous receptor up- and down-regulation, respectively. After implantation into mice and exposure to the natural MC1R agonist alpha-melanocyte-stimulating hormone (alpha-MSH), cell-surface MC1R expression was evaluated by competition binding experiments in tumor membrane preparations. In B 16F1 cells, a single injection of 50 to 500 microg alpha-MSH induced a rapid but moderate dose-dependent MC1R down-regulation which could be totally reverted within 16-24 h. By continuous administration of alpha-MSH via osmotic minipumps, MC1R down-regulation was considerably amplified and reached the level observed in vitro, demonstrating that prolonged receptor interaction was necessary to induce a maximal effect in vivo. Similar results were obtained in vitro, which demonstrates that homologous MC1R regulation in B16F1 cells is essentially independent of the physiological environment. In D10 cells, however, up-regulation could not be reproduced in vivo, suggesting that MC1R up-regulation is more dependent on the physiological environment. These results demonstrate the importance of in vivo receptor regulation studies, in particular in view of the potential use of MC1R as a target for melanoma therapy.

Animals↗