The role of viscoelasticity of collagen fibers in bovine articular cartilage was examined in compression and tension using stress relaxation measurements in the axial direction (normal to the articular surface). Experimentally, for a given axial strain, both peak and equilibrium loads were higher in tension than in compression, whereas stress ...

OBJECTIVE: The purpose of the present study was to extend a previous work in a sample of American undergraduates demonstrating the effects of situational factors on reported anger expression behavior and blood pressure. METHOD: General and domain-specific anger expression behavior and subjective work stress were assessed in 218 nurses from ...

Peritraumatic dissociation (PD) is one of the best predictors of posttraumatic stress disorder (PTSD). In this pilot study, we examined cardiovascular psychophysiology and negative emotions in 19 adults who, retrospectively, reported experiencing high or low levels of PD during the worst trauma of their lives. In a contiguous series of ...

INTRODUCTION: The aim of this study was to determine the characteristics of heart rate variability (HRV), blood pressure variability (BPV), and baroreflex gain (BRG) at rest and during orthostatic stress in patients with clinical criteria of inappropriate sinus tachycardia (IST). METHODS AND RESULTS: Beat-to-beat HRV and BPV, measured by time- ...

The cyclic stresses in the cranium caused by pulsation of the brain play an important role in the design of materials for cranioplasty, as well as craniofacial development. However, these stresses have never been quantified. In this study, the force in the epidural space against the cranium was measured intraoperatively ...

BACKGROUND: Optimal motor control of the spine depends on proprioceptive input as a prerequisite for co-ordination and the stability of the spine. Muscle spindles are known to play an important role in proprioception. Animal experiments suggest that an increase in sympathetic outflow can depress muscle spindle sensitivity. As the muscle ...

Exposure to racial discrimination has been identified as an adverse biopsychosocial stressor that may be related to the prevalence of hypertension in African Americans. The overall objective of this research was to estimate aspects of the effects of self-reported exposure to stress-related racial discrimination and hypertension likelihood in a sample ...

Growing evidences suggest a role of oxidative stress in hypertension and cardiac hypertrophy. The fructose (60%)-fed rat represents a model of metabolic syndrome, associating insulin resistance and high blood pressure. In this model, hypertension, cardiac and vessels hypertrophy and markers of oxidative stress were determined. In addition, the production of ...

Increasing physical activity has been shown to reduce physiological markers of cardiovascular disease, such as high blood pressure, vascular endothelial cell reactivity and arterial stiffness. In this issue of Clinical Science, Hägg and colleagues have chosen the spontaneously hypertensive rat model to investigate the effect of exercise on vascular function. ...

BACKGROUND: Research on religion and health suggests general health benefits for those who are more religiously involved. Particular aspects of religiosity that may influence this finding, however, have not been sufficiently investigated. PURPOSE: This study was designed to explore the relationship between religious orientation (intrinsic, extrinsic) and blood pressure reactivity ...

BACKGROUND: Epidemiological studies have repeatedly shown inverse associations between size at birth and blood pressure in later life. There is some evidence to suggest that exaggerated blood pressure responses to psychological stressors are a forerunner of sustained hypertension. OBJECTIVE: To determine whether individuals who were smaller at birth have greater ...

The aim of this study was to investigate the efficacy of Ondamtanggamibang, a Korean traditional herbal remedy, as a treatment of stress-related psychophysiological variables in healthy medical students experiencing examination stress. Forty volunteers were randomly assigned to either an herbal remedy group (n = 20) or a placebo control group ...

The molecular mechanism for the transition from cardiac hypertrophy, an adaptive response to biomechanical stress, to heart failure is poorly understood. The mitogen-activated protein kinase p38alpha is a key component of stress response pathways in various types of cells. In this study, we attempted to explore the in vivo physiological ...

Several electrocardiographic indices for repolarization heterogeneity have been proposed previously. The behavior of these indices under two different stressors at the same heart rate (i.e., normotensive gravitational stress, and hypertensive isometric stress) was studied. ECG and blood pressure were recorded in 56 healthy men during rest (sitting with horizontal legs), ...

1. Phytoncides are volatile substances released mainly from trees. We studied whether phytoncides can reduce stress responses in stroke-prone spontaneously hypertensive rats (SHRSP). 2. Under the restraint stress, SHRSP exposed to phytoncides showed lower blood pressure than those without the exposure (186.8 +/- 3.9 vs 207.7 +/- 3.4 mmHg, respectively, ...

Blood coagulation activation might be one mechanism linking acute mental stress with coronary events. We investigated the natural habituation of coagulation responses and recovery to short-term mental stress. Three times with one-week intervals, 24 men (mean age 47 +/- 7 years) underwent the same 13-min stressor (preparation, job interview, mental ...

Perturbations that load or unload baroreceptors do not alter skin sympathetic nerve activity (SSNA) in normothermic individuals. However, in pronounced heat-stressed individuals, when a significant component of the SSNA signal is sudomotor and possibly vasodilator in origin, the effects of baroreceptor unloading via an orthostatic stress on SSNA remain unclear. ...

Three recent studies reveal that the unloaded length of a carotid artery increases significantly and rapidly in response to sustained increases in axial extension. Moreover, such lengthening involves an "unprecedented" increase in the rate of turnover of cells and matrix. Although current data are not sufficient for detailed biomechanical analyses, ...

BACKGROUND: The contribution of stress to obesity-related cardiovascular disease is uncertain. The purpose of this study was to examine the influence of body composition on stress-induced pressure natriuresis. METHODS: Dual energy x-ray absorptiometry was performed in 127 African American and white youths to assess lean body mass (LBM), fat mass ...

Reactive oxygen species (ROS) has been implicated in the pathogenesis of many diseases including hypertension. Therefore, certain compounds with antioxidative capacity are believed to be protective against such diseases. Some components of garlic are known to possess antioxidative properties. Therefore, in the present study we investigated the effect of short-term ...

OBJECTIVE: Stroke-prone spontaneously hypertensive rats (SHRSP) are known to have sympathetic hyperactivity to various stimuli. In the search for 'intermediate phenotypes' inferring the function of hypertension genes, the present study assessed responsiveness to cold stress in a congenic strain derived from SHRSP/Izm and Wistar-Kyoto/Izm (WKY/Izm). DESIGN: A congenic strain, WKYpch1.0, ...

Autonomic responses may underlie associations among anxiety, vestibular dysfunction, and unexplained syncope. Mental stress (MS), an anxiety-inducing stimulus, causes forearm vasodilation, whereas the vestibulosympathetic reflex (VSR) causes forearm vasoconstriction. The purpose of this study was to examine the combined effects of mental and vestibular stimulation on neurovascular control in the ...

Approaches for monitoring depth of anesthesia can be influenced by things other than anesthetics. In this study, we evaluated the influence of acupressure on the A-line autoregressive index (AAI) and on stress levels in unsedated volunteers. Fifteen unsedated adult volunteers received pressure on the acupuncture Extra 1 point (EP) and ...

The adult heart responds to stress signals by hypertrophic growth, which is often accompanied by activation of a fetal cardiac gene program and eventual cardiac demise. We showed previously that histone deacetylase 9 (HDAC9) acts as a suppressor of cardiac hypertrophy and that mice lacking HDAC9 are sensitized to cardiac ...

In this paper the torque of an oesophagus is studied for physiological and diabetic conditions. Since the function of the oesophagus is mainly mechanical, this work is focused on providing quantitative measurement of the passive biomechanical properties of the oesophagus torque. The oesophagus was treated as a membrane when calculating ...

This study was undertaken to test the hypothesis that basal sympathetic activity and sympathetic reactivity to stress are increased in patients with essential hypertension. One hundred and fifteen randomly selected patients with essential hypertension and an equal number of age- and sex-matched normal controls were included in this study. Various ...

This multi-method study aimed to disentangle objective and subjective components of job stressors and determine the role of each for hypertension risk. Because research on job stressors and hypertension has been exclusively based on self-reports of stressors, the tendency of some individuals to use denial and repressive coping might be ...

In addition to actual social interactions, internal representations of supportive ties could affect mechanisms linking relationships and health. Undergraduates (41 men, 41 women) wrote about supportive ties or casual acquaintances. Supportive ties were rated as warmer and less controlling than acquaintances, and writing about them evoked reductions in negative affect, ...

Hydrostatic pressure is a well-known physical stimulus, but its effects on cell physiology have not been clarified. To investigate pressure effects on Escherichia coli, we carried out DNA microarray analysis of the entire E. coli genome. The microarray results showed pleiotropic effects on gene expression. In particular, heat- and cold-stress ...

The neuroendocrine hormones ACTH and corticotropin- releasing factor (CRF), which are involved in the stress response, have acute effects on arterial pressure. New evidence indicates that urocortin (UCN), the putative agonist for the CRF type 2 receptor, has selective cardiovascular actions. The responses to long-term infusions of these hormones, both ...

This study sought to determine the influence of gender and/or race on the hemodynamic response to dobutamine during dobutamine stress echocardiography. Blood pressure response patterns differed by gender and race, and completion of testing was often limited because of adverse events, namely, hypertension. Gender and racial differences in blood pressure ...

This study tested the hypothesis that the inflammatory cytokine, interleukin-6, contributes to the hypertensive response to acute psychosocial stress, caused by switching male mice to a cage previously occupied by a different male mouse. Male C57BL6 (WT) and interleukin-6 (IL-6) knockout (KO) mice were implanted with biotelemetry devices to monitor ...

Alexithymia has been prospectively associated with all-cause mortality and with cardiovascular morbidity. Here, stress-induced autonomic reactivity and recovery were examined as potential pathways linking alexithymia to cardiovascular disease. The relation of alexithymia to blood pressure, heart rate, and other cardiovascular parameters derived from impedance cardiography (N = 80) and heart ...

Cardiac hypertrophy is a physiological adaptive response by the heart to pressure overload. However, after prolonged periods, this initial adaptive response becomes maladaptive, leading to increased mortality and morbidity from heart failure. Recently, 3-hydroxyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, or statins, have been shown to inhibit cardiac hypertrophy by cholesterol-independent ...

BACKGROUND AND AIM: The function of the common bile duct is to transport bile from the liver and the gall bladder to the duodenum. Since the bile duct is a distensible tube consisting mainly of connective tissue, it is important to obtain data on the passive mechanical wall properties. The ...

Cardiovascular and sympathoadrenal responses to a reproducible mental stress test were investigated in eight healthy young men before and during intravenous infusion of the nitric oxide (NO) synthesis inhibitor N-monomethyl-L-arginine (L-NMMA). Before L-NMMA, stress responses included significant increases in heart rate, mean arterial pressure, and cardiac output (CO) and decreases ...

OBJECTIVE: The hypothesis that increased blood pressure reactivity to stress is an early risk marker of hypertension was tested in a 1994 follow-up of the 1974 to 1978 Air Traffic Controller Health Change Study sample. METHODS: Assessments in 1974 to 1978 included physical examinations and recordings (every 20 minutes for ...

PURPOSE: Previous studies have documented elevations in indices of sympathetic activity in cats and humans with interstitial cystitis (IC). To examine potential autonomic dysregulation in IC we examined the effects of a laboratory mental stress challenge on blood pressure and heart rate (HR) in patients with IC and healthy controls. ...

OBJECTIVE: Oxidative stress and NO are thought to play important roles in arteriosclerosis pathogenesis, a major cause of white matter lesions in the brain. Therefore, we examined whether NO metabolites (NOx) and 8-iso-prostaglandin F(2alpha) (IsoP) levels in vivo correlated with the severity of periventricular hyperintensity (PVH) to evaluate potential roles ...

The role played by the history of packing in the behaviour of a granular material confined in a column is studied experimentally. The mean pressure applied by the granular assembly to the base is measured as a function of the height of material poured in the column. We obtain reproducible ...

OBJECTIVE: This study compared the effects of acute mental stress on cardiovascular and subjective responses and platelet activation in male patients with established coronary artery disease (CAD) and age-matched controls. METHODS: We assessed 17 male CAD patients aged 44 to 59 years and 22 healthy male controls. Blood pressure, heart ...

Mechanical forces related to pressure and flow are important for cell hypertrophy and proliferation. There are still a few studies that examine responses of human vascular smooth muscle cells to pure pressure stress (transmural pressure). It is unclear as to which mechanisms are involved in cellular responses to pressure elevation. ...

BACKGROUND: Anger management style is related to acute and chronic pain, but it is not clear whether anger arousal is needed for these associations to emerge or whether physiological mechanisms mediate these links. PURPOSE: "Trait x Situation" models were examined to determine whether relationships between anger-out and pain and anger-in ...

BACKGROUND: Spaceflight studies have demonstrated that adaptation to increased gravitational stress after prolonged microgravity includes sympathetic activation, water retention, and arterial pressure increase, i.e. is very similar to essential hypertension, which looks like an advanced stage of adaptation to a further increase in gravitational stress. MATERIAL/METHODS: Theoretical analysis and literature ...

Yeasts are unicellular organisms that are exposed to a highly variable environment, concerning the availability of nutrients, temperature, pH, radiation, access to oxygen and, specially, water activity. Evolution has selected yeasts to tolerate, to a certain extent, these environmental stresses. High hydrostatic pressure (HHP) exerts a broad effect upon yeast ...

Excessive stress loadings in daily life are believed to play a role in the development of affective disorders. Our recent finding of enhanced neuroendocrine activation during stress of hypoglycemia after repeated antidepressant treatment in healthy men supports the hypothesis that the clinical effects of antidepressant treatment may be partly due ...

There is a general lack of valid tools to measure work stress of Malaysian. This study examines the validity and reliability of the Pressure Management Inventory (PMI). Reliability was evaluated using test retest method, and its correlation coefficient was calculated using Pearson's r. Internal consistencies were examined using Cronbach's Alpha. ...

Superoxide has been shown to be an important intracellular mediator of actions of angiotensin II. Recently, we found that blockade of angiotensin II type-1 receptors in the rostral ventrolateral medulla (RVLM) abrogated the pressor effect of emotional stress in rabbits. In the present study, we examined the influence of superoxide ...

A pseudo-strain energy function (pseudo-SEF) describing the biomechanical properties of large conduit arteries under the influence of vascular smooth muscle (VSM) tone is proposed. In contrast to previous models that include the effects of smooth muscle contraction through generation of an active stress, in this study we consider the vascular ...

Basal septal hypertrophy (BSH), a cause of left ventricular outflow tract (LVOT) obstruction, is thought to occur by increased ventricular dynamics. The aim of the study was to evaluate the effect of pharmacologic stress on LVOT gradients in a group of hypertensive patients with BSH. Dobutamine stress was used in ...