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At least 451 records · Page 25Linked to original sources
PubMed1986

[Left ventricular function in dilated cardiomyopathy. Noninvasive determination of end-systolic stress-diameter and shortening fraction-stress relations].

The ejection fraction and fractional shortening are parameters of left ventricular function dependent on the conditions of load. They are not perfect indices of myocardial contractility. The study of the relationships between stress and diameter and fractional shortening and stress in end-systole provides a better means of assessing the contractile state of the myocardium. The relationships between end-systolic stress-diameter and end-systolic stress-fractional shortening were studied non-invasively in 10 normal subjects (Group I) and 7 patients with severe dilated cardiomyopathy (Group II). End-systolic longitudinal stress of the left ventricle was calculated from Grossman's formula by coupling automatic measurement of blood pressure (cuff method) with simultaneous M mode recordings guided by 2D echocardiography. The line of regression of end-systolic stress-end-systolic diameter was determined in all cases from a series of 14 points obtained after sublingual administration of 10 mg of isosorbide dinitrate. The line of regression of fractional shortening-end-systolic stress was established in both groups by using the values observed under basal conditions and at the peak of action of the isosorbide dinitrate. The following results obtained: Under basal conditions, patients in Group II had greater end-diastolic diameters (69 +/- 8 vs 49 +/- 4 cm, p less than 0.01), greater end-systolic diameters (61 +/- 8 vs 33 +/- 4 mm, p less than 0.001) and higher end-systolic stress (140 +/- 54 vs 67 +/- 13 10(3) dyn/cm2, p less than 0.001). Fractional shortening was lower in Group II than in Group I (12 +/- 5 vs 33 +/- 5%, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Comparison of diagnostic value of coronary artery disease between ATP-stress and exercise-stress thallium myocardial SPECT images].

A study was made between adenosine triphosphate disodium (ATP)-stress thallium myocardial scintigrams and exercise-stress scintigrams to compare their respective extents and degree of defects. The subjects of the study were 33 ischemic heart disease patients, who received ATP stress and treadmill exercise stress with a mean interval of 25 days. ATP was infused for 5 minutes with an infusion rate of 0.16 or 0.18 mg per kg of body weight per minute. Thallium was injected three minutes after infusion. The percent-defect index (percentage of the extent and degree of the defects for all 33 patients), was calculated with visual scoring using a five-zone myocardial division method and semi-quantitative four-grade representation method for both the ATP and exercise SPECT images. The extent of the defects in ATP- and exercise-stress images was 51.5% and 44.2%, and that in redistribution images was 36.4% and 33.9%, respectively. The degree of defects in ATP- and exercise-stress images was 35.8% and 32.3%, while that in redistribution images was 20.8% and 17.2%, respectively (p = NS in all cases). In conclusion, the image quality of thallium SPECT with ATP stress was equivalent to that of exercise stress, indicating identical diagnostic values for coronary lesions.

Adenosine Triphosphate↗
PubMed2004

Delayed effects of chronic variable stress during peripubertal-juvenile period on hippocampal morphology and on cognitive and stress axis functions in rats.

Animal studies on the effects of chronic variable stress during the peripubertal-juvenile period on hippocampal structure and function are lacking. Twenty-eight-day-old Sprague-Dawley rats were subjected to random, variable physical or social stress regimens for 4 weeks. Hippocampal volume was found to continue to grow in all lamina examined during the transition into young adulthood. Our variable physical stress paradigm led to inhibition of this growth in the CA1 pyramidal cell layer (PCL) and in the dentate gyrus-granular cell layer (DG-GCL), which reached full arrest in the CA3-PCL. Volume deficits were first observed after chronic stress exposure when 3 weeks, but not 24 h, of recovery had elapsed. Moreover, these volume deficits were associated with impairments in the Morris water-maze navigation, sustained down-regulation in the basal hippocampal glucocorticoid receptor gene expression, and deficits in the shutdown of acute stress-induced corticosterone secretion. Volume changes both due to normal maturation and after chronic stress exposure were independent of neuron number. Thus, a peripubertal-juvenile chronic stress paradigm that leads to significant alterations in the limbic-hypothalamic-pituitary-adrenal axis can produce robust effects in hippocampal structure and cognitive ability, lasting into adulthood.

Age Factors↗
PubMed2006

Social stress is as effective as physical stress in reinstating morphine-induced place preference in mice.

RATIONALE: Relapse to drug-seeking in abstinent heroin addicts and reinstatement in experimental animals are observed when exposed to drug-associated stimuli or cues, the drug itself, and stressful events. It has been shown that footshock-induced stress increases the rewarding effects of opiates, delays extinction, and induces the reinstatement of drug-seeking. However, the effects of social stress on the reinstatement of opiate-seeking after extinction has not been studied. OBJECTIVES: The role of physical (restraint and tail pinch) and social (social defeat) stressors on the reinstatement of morphine-induced conditioned place preference (CPP) was evaluated. METHODS: Adult male OF1 mice were conditioned with 10, 20, or 40 mg/kg of morphine or saline. Only morphine-conditioned animals acquired CPP. All mice underwent extinction sessions until the CPP was extinguished. Then, the effects of physical or social stress on the reinstatement of CPP were evaluated. Morphine- and saline-conditioned animals were exposed to the respective stressor or control stress condition immediately or 15 min before reinstatement tests. In experiment 1, animals underwent restraint for 15 min. In experiment 2, animals were exposed to tail pinch or placed in a cage without any manipulation for 15 min. In experiment 3, animals performed an agonistic encounter with an isolated or anosmic mouse or were placed in a cage without any social contact or manipulation. RESULTS: Restraint, tail pinch, and social defeat in an agonistic encounter with an isolated mouse produce the reinstatement of CPP in morphine-conditioned animals. CONCLUSIONS: These data demonstrate that social stress is as effective as physical stress in reinstating morphine-seeking.

Agonistic Behavior↗
PubMed1996

Oxidative stress associated with exercise, psychological stress and life-style factors.

Oxidative stress is a cellular or physiological condition of elevated concentrations of reactive oxygen species that cause molecular damage to vital structures and functions. Several factors influence the susceptibility to oxidative stress by affecting the antioxidant status or free oxygen radical generation. Here, we review the effect of alcohol, air pollution, cigarette smoke, diet, exercise, non-ionizing radiation (UV and microwaves) and psychological stress on the development of oxidative stress. Regular exercise and carbohydrate-rich diets seem to increase the resistance against oxidative stress. Air pollution, alcohol, cigarette smoke, non-ionizing radiation and psychological stress seem to increase oxidative stress. Alcohol in lower doses may act as an antioxidant on low density lipoproteins and thereby have an anti-atherosclerotic property.

Air Pollution↗
PubMed2006

Safety of stress echocardiography (from the International Stress Echo Complication Registry).

The safety of any diagnostic test is a major issue in deciding its practicability and cost-effectiveness. The aim of this study was to evaluate the safety of various stress echocardiographic modalities in the "real world." From February 1998 to January 2004, a simple written questionnaire was distributed to echocardiography laboratories across the world known to perform stress echocardiography. The following categories of major complications (known to occur during stress testing) were indicated: sustained ventricular tachycardia (> 30 beats/min), ventricular fibrillation, myocardial infarction, third-degree atrioventricular block, severe hypotension requiring therapy, cardiac asystole, cardiac rupture, stroke, and death. Three hundred centers were polled, from which 71 co-investigators responded and reported on 85,997 patient examinations. Exercise was used in 26,295 cases, dobutamine in 35,103, and dipyridamole in 24,599 cases. Life-threatening events occurred in 86 cases: during exercise in 4 patients (event rate 1 in 6,574), during dobutamine infusion (small dose for viability and/or large dose for ischemia) in 63 patients (event rate 1 in 557), and during dipyridamole stress testing in 19 patients (event rate 1 in 1,294). Of the 86 patients with complications, 5 died during dobutamine stress testing (ventricular fibrillation, n = 2; cardiac rupture, n = 3) and 1 after dipyridamole testing (cardiogenic shock). In conclusion, stress echocardiography is a safe method in the real world, but serious complications may occur. Exercise seems safer than pharmacologic stress and dipyridamole safer than dobutamine, possibly because of preselection criteria.

Cardiotonic Agents↗
PubMed2006

Blunted HPA axis response to stress influences susceptibility to posttraumatic stress response in rats.

BACKGROUND: Posttraumatic stress disorder (PTSD) is associated with low levels of circulating cortisol, and recent studies suggest that cortisol administration may reduce PTSD symptoms. This study investigated the role of cortisol in the manifestation of anxiety- and fear-like symptoms in an animal model of PTSD. METHOD: Magnitude of changes in prevalence of anxiety-like behaviors on the elevated plus-maze and nonhabituated exaggerated startle reaction were compared in three strains of rats exposed to predator stress, with and without prior corticosterone treatment. Extreme behavioral changes in both paradigms implied an extreme behavioral response (EBR), representing PTSD-like symptoms. RESULTS: Lewis rats exhibited greater baseline anxiety-like behaviors and greater stress-induced increases in anxiety-like behaviors than Fischer F344 or Sprague-Dawley rats, with only minor corticosterone increases following stress. Prevalence of EBR was 50% among Lewis rats compared with 10% of Fischer F344 and 25% of Sprague-Dawley rats. Administering corticosterone 1 hour before stress exposure reduced the prevalence of EBR from 50% to 8% in the Lewis rats. CONCLUSIONS: These results suggest that a blunted HPA response to stress may play a causal role in this model of PTSD and that this susceptibility may be prevented by administration of cortisol before stress exposure.

Analysis of Variance↗
PubMed2004

Estradiol protects against oxidative stress induced by chronic variate stress.

Neurochemical gender-specific effects have been observed following chronic stress. The aim of this study was to verify the effects of chronic variable stress on free radical production (evaluated by DCF test), lipoperoxidation (evaluated by TBARS levels), and total antioxidant reactivity (TAR) in three distinct structures of brain: hippocampus, cerebral cortex and hypothalamus of female rats, and to evaluate whether the replacement with estradiol in female rats exerts neuroprotection against oxidative stress. Results demonstrate that chronic stress had a structure-specific effect upon lipid peroxidation, since TBARS increased in hypothalamus homogenates of stressed animals, without alterations in the other structures analyzed. Estradiol replacement was able to counteract this effect. In hippocampus, estradiol induced a significant increase in TAR. No differences in DCF levels were observed. In conclusion, the hypothalamus is more susceptible to oxidative stress in female rats submitted to chronic variable stress, and this effect is prevented by estradiol treatment.

Animals↗
PubMed2003

Helping adolescents cope with stress during stressful times.

Increasing levels of stress in the daily lives of adolescents is an important health concern. Adolescents experience a variety of stressful situations and use a wide range of coping strategies to help effectively manage stress. Recent research on adolescent coping with stressful situations is reviewed. Findings support an association between coping and adolescent health problems, chronic physical illness, and mental health. More research is needed to investigate the long-term benefits of coping with stress on adolescent health and well-being. Specific recommendations for helping adolescents cope with stressful situations are discussed. Health care providers are encouraged to assess how adolescents cope with acute and chronic stressors and provide adolescents with information about coping with stressful situations.

Adaptation, Psychological↗
PubMed2003

The predictive power of peritraumatic dissociation and acute stress symptoms for posttraumatic stress symptoms: a three-month prospective study.

OBJECTIVE: The authors prospectively examined the power of peritraumatic dissociation and acute stress symptoms in predicting posttraumatic stress disorder (PTSD) symptoms. METHOD: Thirty-five assault victims were assessed with the Peritraumatic Dissociative Experiences Questionnaire within 24 hours of the assault. Participants were reassessed 2 weeks after the trauma with the Stanford Acute Stress Reaction Questionnaire and 3 months after the trauma with the Clinician-Administered PTSD Scale and the Impact of Event Scale. Correlational analyses and a hierarchical multiple regression were conducted. RESULTS: Peritraumatic dissociation and acute stress symptoms were correlated with later PTSD symptoms and diagnosis. Together, peritraumatic dissociation and acute stress symptoms accounted for 33% of the variance in PTSD symptoms. CONCLUSIONS: These results support earlier findings that peritraumatic dissociative experiences and acute stress are robust predictors of PTSD. Such symptoms may be of use for identifying at an early stage individuals at highest risk of remaining symptomatic. Future studies should investigate the predictive power of specific peritraumatic and acute stress disorder symptom clusters.

Adult↗
PubMed1986

Stress inoculation therapy with anxiety and stress disorders of acute psychiatric inpatients.

Twenty-six consecutive inpatient psychiatric admissions with severe stress and anxiety disorders were assigned to three treatment groups: stress inoculation therapy; a combination of stress inoculation and medication therapy; and medication therapy. The dependent measures indicate that stress inoculation therapy was superior to chemotherapy from pre- to post-testing and from baseline to posttesting in reducing symptoms of depression, anxiety, and overall subjective distress. In a 3-year follow-up, subjects in the stress inoculation therapy group tended to require fewer readmissions for psychiatric problems than the other treatment groups. It is proposed that stress inoculation therapy is effective in reducing symptoms of severe anxiety and stress reactions of acute psychiatric inpatients and that medication sometimes may have an inhibitive effect upon possible gains through psychotherapy.

Adult↗
PubMed2002

Effects of stress hormones on traumatic memory formation and the development of posttraumatic stress disorder in critically ill patients.

A majority of patients after intensive care treatment report traumatic memories from their stay in the intensive care unit (ICU). Traumatic memories can be associated with the development of posttraumatic stress disorder (PTSD) in a subpopulation of these patients. In contrast to other patient populations at risk for PTSD, patients in the ICU often receive exogenously administered stress hormones like epinephrine, norepinephrine, or cortisol for medical reasons and are extensively monitored. ICU patients therefore represent a suitable population for studying the relationship between stress hormones, traumatic memories, and the development of PTSD. Studies in long-term survivors of ICU treatment demonstrated a clear and vivid recall of different categories of traumatic memory such as nightmares, anxiety, respiratory distress, or pain with little or no recall of factual events. The number of categories of traumatic memory recalled increased with the total administered dosages of stress hormones (both catecholamines and cortisol), and the evaluation of these categories at different time points after discharge from the ICU showed better memory consolidation with higher dosages of stress hormones administered. However, the administration of stress doses of cortisol to critically ill patients resulted in more complex findings as it caused a significant reduction in PTSD symptoms measured after recovery. This effect can possibly be explained by a differential influence of cortisol on memory. Increased serum cortisol levels not only result in consolidation of emotional memory but are also known to cause a temporary impairment in memory retrieval which appears to be independent of glucocorticoid effects on memory formation. Disrupting retrieval mechanisms with glucocorticoids during critical illness may therefore act protectively against the development of PTSD by preventing recall of traumatic memories. Our findings indicate that stress hormones influence the development of PTSD through complex and simultaneous interactions on memory formation and retrieval. Our studies also demonstrate that animal models of aversive learning are useful in analyzing and predicting clinical findings in critically ill humans.

Affect↗
PubMed1989

Neuroendocrine responses to nicotine and stress: enhancement of peripheral stress responses by the administration of nicotine.

Habitual smokers frequently report that when they are stressed smoking helps them to relax. One potential explanation for the reported stress ameliorating effect of smoking is that cigarette consumption (nicotine self-administration) may decrease the sympathetic autonomic nervous system activity which is associated with the stress response. In the present study, rabbits prepared with chronic vascular cannulae were used to study the effects of nicotine administration on plasma corticosterone, catecholamine (epinephrine, norepinephrine and dopamine) and glucose responses to physical restraint stress. Nicotine (0.025, 0.05 or 0.10 mg nicotine base/kg body weight) was administered for 10 days prior to the "stress test" to allow for the development of habituation/tolerance to its acute toxic effects. Independent administration of nicotine, or the application of the physical restraint stressor, resulted in increases in the plasma concentrations of corticosterone, epinephrine, norepinephrine, and glucose. Nicotine administration during restraint stress enhanced the increase in plasma corticosterone and epinephrine, as compared to the responses induced by either factor alone. The results suggest that the stress ameliorating effect of continued cigarette smoking, as reported by habitual smokers, is not due to a reduction in the activity of the peripheral sympathetic autonomic nervous system.

Animals↗
PubMed1994

Previous stress increases in vivo biogenic amine response to swim stress.

In vivo microdialysis was used to determine biogenic amines in medial prefrontal cortex of rats exposed to eight minutes of swim stress on two consecutive days. On the first day of stress, norepinephrine (NE) efflux increased by 183% over baseline after stress, while dopamine (DA) and serotonin (5-HT) remained stable throughout. On the second day of stress, a robust increase was observed in all 3 neurotransmitters measured, with (NE), (DA), and (5-HT) increasing by 310%, 441% and 496% respectively, and remaining elevated for an hour or more after stress. This suggests that the first exposure to swim stress, while not causing dramatic changes in biogenic amine release, may sensitize biogenic amines in medial prefrontal cortex to subsequent swim stress. Our results also serve as preliminary data concerning the neurochemical changes which might underlie the forced swimming model of "behavioral despair".

Animals↗
PubMedDate not supplied

Consistency in physiological stress responses and electromyographic activity during induced stress exposure in women and men.

Physiological responses serve the role as objective indicators of stress as well as a link between psychosocial stress and various health outcomes. The aim of the present exposure session was to compare different physiological stress responses (systolic and diastolic blood pressure, heart rate, urinary epinephrine and norepinephrine, salivary cortisol) as well as trapezius muscle activity, measured by surface electromyography, during mental and physical stress in 11 women and ten men. The results show significantly increased activity in all measures but cortisol and significant associations between sympathetic arousal and EMG activity. The association between sympathetic arousal and muscle activity is of importance for understanding the high prevalence of musculoskeletal disorders in mentally stressful but physically light work tasks. Men had higher blood pressure and a more pronounced increase in epinephrine output than women, whereas women had higher heart rate. It was concluded that sympathetic activity is more sensitive to moderately intense stress exposure than pituitary adrenocortical (cortisol) activity and that men respond to performance stress with more epinephrine output than women. Although the correlations between the different indicators of sympathetic arousal were high, together they could still only explain 30-70% of the inter-individual variance. Thus, several parameters are needed in order to obtain a reliable measure of sympathetic activity.

Adult↗
PubMedDate not supplied

Limbic hypertension induced by stress and septal stimulation. Stress-locked-in hypertension.

For this study, it was postulated that hypertension of emotional origin is generated within the limbic system. To validate this thesis, septal induced blood pressure elevations were combined with a stressful experience in adult rats (spontaneously hypertensive and Wistar Kyoto rats). Stress consisted of intermittent confinement in a plexiglass tube. The results revealed that hypertension induced by electric stimulation of the septum during the stressful state could subsequently be elicited by the stressful state alone, without electric stimulation of the septum. It was postulated that the cortically modulated stress circuit converged with the electrically activated limbic pressor circuit at the level of the septum. This convergence resulted in the formation of one cortico-limbic circuitry which could be activated by stress alone. This underlying mechanism may be considered as a model of neural sensitization in the production of stress-induced limbic hypertension.

Animals↗
PubMed2004

Buckling of inner cell wall layers after manipulations to reduce tensile stress: observations and interpretations for stress transmission.

The inner layer of the cell wall in tissues that are under tensile stress in situ, e.g. epidermis and collenchyma of etiolated sunflower hypocotyls, shows a pattern of transverse folds when the tissues are detached and plasmolysed. This can be observed by Nomarski imaging of inner surfaces of the outer cell walls and electron microscopy of longitudinal sections after peeling the epidermis and bathing it in plasmolysing solutions. The folds are apparently caused by buckling of the inner layer due to the longitudinal compressive force exerted on this layer by the outer wall layer, when it shrinks after the removal of the longitudinal tensile stresses. In these stresses, two components can be distinguished: the tissue stress, disappearing on peeling, and that caused directly by turgor pressure, disappearing in hyperosmotic solution. Investigation of the buckling indicates that the outer layer of the cell wall transmits in situ most of the longitudinal tensile stress in the wall. The common concept that the inner layer of the wall is the region bearing most stress and therefore regulating growth can still be valid with respect to the transverse stress component.

Cell Wall↗
PubMed1989

Adrenocortical and behavioral responses to repeated stressors: toward an animal model of chronic stress and stress-related mental illness.

Research in chronic stress has been hampered by the absence of an operational definition for that condition. To explore possible criteria for chronic stress, we repeatedly exposed rats to 2 hr of tail shock per day. After several days, we found elevated prestress corticosterone levels and abnormal behavior, including decreased food consumption, fear-like suppression of activity immediately before stress, greater hesitancy to drop from a suspended wire, and decreased exploratory behavior in a novel environment. A less intensely stressed group of rats also had elevated prestress corticosterone levels, but not the abnormal behaviors that persisted in shocked rats after the stress sessions were discontinued. We propose that abnormalities in both adrenocortical function and behavior are a better marker for chronic stress than abnormalities in either of these systems alone. The animal model we have described may be useful for studying factors that contribute to development of chronic stress or PTSD.

Adrenal Cortex↗