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PubMed2006

Over-expression of different aldehyde dehydrogenase genes in Arabidopsis thaliana confers tolerance to abiotic stress and protects plants against lipid peroxidation and oxidative stress.

Aldehyde dehydrogenases (ALDHs) play a major role in the detoxification processes of aldehydes generated in plants when exposed to abiotic stress. In previous studies, we have shown that the Arabidopsis thaliana ALDH3I1 gene is transcriptionally activated by abiotic stress, and over-expression of the ALDH3I1 gene confers stress tolerance in transgenic plants. The A. thaliana genome contains 14 ALDH genes expressed in different sub-cellular compartments and are presumably involved in different reactions. The purpose of this study was to compare the potential of a cytoplasmic and a chloroplastic stress-inducible ALDH in conferring stress tolerance under different conditions. We demonstrated that constitutive or stress-inducible expression of both the chloroplastic ALDH3I1 and the cytoplasmic ALDH7B4 confers tolerance to osmotic and oxidative stress. Stress tolerance in transgenic plants is accompanied by a reduction of H2O2 and malondialdehyde (MDA) derived from cellular lipid peroxidation. Involvement of ALDHs in stress tolerance was corroborated by the analysis of ALDH3I1 and ALDH7B4 T-DNA knockout (KO) mutants. Both mutant lines exhibited higher sensitivity to dehydration and salt than wild-type (WT) plants. The results indicate that ALDH3I1 and ALDH7B4 not only function as aldehyde-detoxifying enzymes, but also as efficient reactive oxygen species (ROS) scavengers and lipid peroxidation-inhibiting enzymes. The potential of ALDHs to interfere with H2O2 was also shown for recombinant bacterial proteins.

Aldehyde Dehydrogenase↗
PubMed2004

Stress induces activation of stress-activated kinases in the mouse brain.

Stress is a part of daily life. However, molecular mechanisms underlying the activation of limbic-hypothalamic-pituitary-adrenal (LHPA) axis remains unknown. In this study, we explored whether activation of the mitogen-activated kinase kinase 4 (MKK4)-c-Jun-N-terminal kinase (JNK) signaling pathway may play a role in the activation of the LHPA axis. We found that forced-swim stress induced elevation of activated MKK4 in the hippocampal formation, amygdala, and hypothalamus. Unlike MKK4, a high basal level of JNK activity is present in many brain areas of unstressed mice. Forced-swim stress significantly elevated JNK activity in the hypothalamus and amygdala and, to a lesser extent, in the cortex, CA1 and CA3 regions, and the dentate gyrus. To further investigate the role of MKK4 and JNK in induction of stress responses, we investigated whether a different stress, namely, restraint stress, induced activation of MKK4 or JNK in the brain. We found that restraint stress also induced elevation of activated MKK4 and JNK in the hippocampal formation, amygdala, and hypothalamus. Because MKK4 and JNK were activated within 5 min following stress, we propose that the MKK4-JNK signaling may be an early neural event in the initiation of neuroendocrine, autonomic and behavioral stress responses.

Amygdala↗
PubMed1998

Uniform stress state in bone structure with residual stress.

Residual stress and strain in living tissues have been investigated from the viewpoint of mechanical optimality maintained by adaptive remodeling. In this study, the residual stresses in the cortical-cancellous bone complex of bovine coccygeal vertebrae were examined. Biaxial strain gages were bonded onto the cortical surface, so that the gage axes were aligned in the cephalocaudal and circumferential directions. Strains induced by removal of the end-plate and the cancellous bone were recorded sequentially. The results revealed the existence of compressive residual stress in the cortical bone and tensile residual stress in the cancellous bone in both the cephalocaudal and the circumferential direction. The observed strains were examined on the basis of the uniform stress hypothesis using a three-bar model for the cephalocaudal direction and a three-layered cylinder model for the circumferential direction. In this model study, the magnitude of effective stresses, which is defined as the macroscopic stress divided by the area fraction of bone material, was found not to differ significantly between cephalocaudal and circumferential directions, although they were evaluated using independent models. These results demonstrate that the uniform stress state of the cortical-cancellous bone structure is consistent with results obtained in the cutting experiment when the existence of residual stress is taken into account.

Animals↗
PubMed1992

Finite element stress analysis of a push-out test. Part 1: Fixed interface using stress compatible elements.

In this first part of a two-part paper, interelement stress compatible finite elements are developed and used to perform the stress analysis of a push-out test with a fixed interface. In the formulation, the required continuity of some of the stresses along either a specific interface or all interelement interfaces is enforced by a penalty procedure. The model is axisymmetric and consists of two cylinders attached to each other through the interface. Various relative material properties and boundary conditions are simulated in order to examine their effects on the interface stresses. Both loadings of axial compression force and axial torque are considered. The predicted results exhibit identical interelement stresses and displacements even when highly dissimilar materials are used. They also exhibit a complex state of interface stresses which depend on the geometry, material arrangement, boundary conditions, and loading. The variation of the shear stress is often highly nonuniform and the radial normal stresses are likely to be large. The present results, therefore, disagree with the common assumptions made in the pull-out tests in the orthopaedic applications. Finally, stress analysis of a number of possible testing configurations could lead to the design of an optimal pull-out test which maximizes the usefulness of the measured results in terms of the interface bond strength and factors affecting it.

Biomechanical Phenomena↗
PubMed2001

Perceived job stress but not individual cardiovascular reactivity to stress is related to higher blood pressure at work.

Psychological stress has been reported to be related to higher blood pressure (BP) and unfavorable cardiovascular profile. However, because of the complexity of personal stress management, a multilevel stress measurement strategy is needed. The aim of this cross-sectional study was to analyze the respective influences of the subjective perception of professional strain (high demand and low latitude) and cardiovascular reactivity to a stress test (Stroop stress test) on BP. Worksite BP was measured in 303 healthy normotensive subjects, 18 to 55 years of age, who worked in the same chemical company. In a subset of 70 randomly selected subjects, 24-hour ambulatory BP was performed to assess BP during working hours. The 20% of subjects who reported the highest job strain (high-strain group) or the highest BP stress reactivity (high-responder group) were compared with the remaining subjects (80%) (non-high-strain or low-responder groups). Subjects who submitted to the highest job strain had significantly higher ambulatory diastolic BP (4.5 mm Hg, P=0.015) during only working hours, whereas BP was similar during the remaining hours. Worksite BP and stress cardiovascular reactivity were similar between job strain groups. BP stress reactivity did not influence worksite and ambulatory BP. Spontaneous BP variability assessed by standard deviation and spectral analysis was equivalent between complementary groups. Prevalence of microalbuminuria was significantly higher in the high-responder group (8.2% versus 2.5% in low responders) and only slightly higher in the high-strain group (6.2% versus 3.2% in non-high strain). Potential confounding factors, such as age, gender, alcohol consumption, salt intake, body mass index, and occupation, which were equivalent between groups, did not interfere with our results. Our study quantifies high-professional strain effects on BP levels that appear to be higher only during the working period and to be independent from spontaneous BP variability and stress BP reactivity.

Adolescent↗
PubMed2004

Stress, burnout, coping and stress management in psychiatrists: findings from a systematic review.

BACKGROUND: Research into stress among psychiatrists has attempted to identify stressors, which can lead to physical illness and psychological distress. AIMS: The aim of the study was systematically to review the current evidence for the effectiveness of stress management interventions for those working in the psychiatric profession. METHOD: A systematic review of the current literature was conducted into stress and stress management within the profession of psychiatry. RESULTS: Twenty-three international studies were included in the psychiatry section of the review. Psychiatrists report a range of stressors in their work, including stress associated with their work and personal stresses. One personal stress, which psychiatrists find very difficult to cope with is patient suicide. Coping strategies include support from colleagues and outside interests. No studies evaluated the use of stress-management interventions for psychiatrists. CONCLUSIONS: Psychiatry is a stressful profession. Psychiatrists identified several stressors in their professional and personal lives.

Adaptation, Psychological↗
PubMed1998

Psychophysiological assessment of stress in chronic pain: comparisons of stressful stimuli and of response systems.

Due to disparate findings across the published studies, the stress-hyperactivity hypothesis has never been fully accepted as a causal mechanism for chronic muscle pain. Two recent comprehensive reviews of the psychophysiological studies of chronic pain came to opposite conclusions about the viability of the hypothesis, which stemmed from differing importance placed on the experimental methodology: the adequacy of stress manipulation. The present study tested the hypotheses that the adequacy of stress manipulation is influenced by stress stimuli type, degree of personal relevance, and selection of criterion for verification of stress experience, and that these factors have a measurable impact on the related physiological responses in a manner that is consistent with a theory of stress applicable to clinical stress disorders. The three factors investigated were: task (imagery, reaction time), relevance (high, low), and manipulation criterion (autonomic, self-report). The tasks were presented to 16 chronic pain patients while muscle, electrodermal, and self-report responses were recorded. Reaction-time tasks and high-relevance conditions led to high muscle and electrodermal responses. Only the high-relevance imagery, however, produced high self-reported distress. Consistent with other research, the present overall data demonstrated differing physiological profiles for different stimuli types. More importantly, these data suggest that the manipulation type and the manipulation criterion influence outcomes of experimental tests of stress on physiological systems, which may directly lead to contrasting conclusions about causal relations between stress and chronic pain conditions.

Adult↗
PubMed1987

Electrocorticogram in rats loaded with SART stress (repeated cold stress).

The electrocorticogram (ECoG) in a SART (specific alternation of rhythm in temperature)-stressed (repeatedly cold-stressed) rat, which is regarded as an experimental model for clinical vagotonic-type dysautonomia, was investigated in the present study by the power spectral technique. 1) Analysis of ECoG in SART-stressed rats during the resting-arousal state indicated a decrease in total power and a decrease in relative power in the delta band, and also an increase in relative power in the theta, alpha and beta bands. 2) In the slow-wave sleeping state, the ECoG of SART-stressed rats indicated a marked increase in total power, an increase in the delta band and decreases in theta, alpha and beta bands. 3) Electric stimulation of the posterior-hypothalamic area evoked alterations of ECoG similar to those caused by SART stress. ECoG response to electric stimulation in SART-stressed rats was less than that in unstressed rats. 4) Lesioning of the posterior-hypothalamic areas prevented SART stress-induced ECoG alterations. SART-stressed rats thus appear to be at a higher consciousness level on awakening but to sleep more soundly. They seem to exhibit greater fluctuation in brain activity than normal rats. There is also the possibility that the posterior-hypothalamic area is responsible to some degree for ECoG alterations in SART-stressed rats.

Animals↗
PubMed1987

Surface epithelial cell damage induced by restraint and water-immersion stress in rats effects of 16,16-dimethyl prostaglandin E2 on stress-induced gastric lesions.

The time-course of gastric mucosal surface epithelial cell damage and macroscopically visible lesions in response to restraint and water-immersion stress (22 degrees C) in rats was examined, and the effects on it of 16,16-dimethyl prostaglandin E2 (dmPGE2) were compared with those of papaverine, timoprazole and atropine. The stress produced surface epithelial cell damage prior to visible lesion, the former increasing in severity with time and reaching a plateau 60 min later, by which time exfoliation of surface epithelial cells was observable along the mucosal folds. In contrast, macroscopically visible lesions appeared 2 hr after stress, and severity continued to increase with time. Pretreatment injections (s.c.) of dmPGE2 (3, 30 micrograms/kg), papaverine (100 mg/kg) and atropine (1 mg/kg) protected the surface cells against stress (1 hr)-induced damage, and inhibited visible lesion formation after 4 hr stress. Timoprazole (30 mg/kg, s.c.) did not protect the surface cells, but did markedly inhibit visible lesion formation. dmPGE2, papaverine and atropine, but not timoprazole, inhibited stress-induced increases in gastric contractions. dmPGE2, timoprazole and atropine, but not papaverine, inhibited acid secretion in stress-conditions. These results indicated that stress induced damage to the gastric mucosa within 1 hr due to increased gastric contractions, and the surface epithelial cell damage developed into macroscopically visible lesions in the presence of acid, and that dmPGE2 protected the surface epithelium against stress-induced damage probably by inhibiting gastric contractions.

16,16-Dimethylprostaglandin E2↗
PubMed1998

Stress ulcer prophylaxis in medical ICU patients: annual utilization in relation to the incidence of endoscopically proven stress ulceration.

OBJECTIVE: To measure changes in the proportion of medical intensive care unit (MICU) patients prescribed pharmacologic stress ulcer prophylaxis therapy over a 4-year period in relation to the incidence of stress-related ulceration detected by endoscopy at our institution. DESIGN: Retrospective 4-year review of pharmacy and endoscopy databases. SETTING: A 35-bed MICU. PATIENTS: Patients (n = 2941) admitted to the MICU for longer than 24 hours, between January 1, 1993, and December 31, 1996, without acute gastrointestinal hemorrhage on admission. METHODS: Records were reviewed to identify patients prescribed pharmacologic stress ulcer prophylaxis (> 24 h of sucralfate or a histamine2-receptor antagonist [H2RA]), and patients with evidence of stress ulceration during endoscopy. RESULTS: The number of patients per year receiving stress ulcer prophylaxis significantly (p < 0.001) decreased between 1993 and 1996: 1993, 492/693 (71%); 1994, 478/798 (60%); 1995, 295/670 (44%); 1996, 164/780 (21%). There was no difference between years in the median duration of stress ulcer prophylaxis therapy or the proportion of patients receiving sucralfate versus H2RA therapy. There was no difference (p = 0.91) between years in the annual incidence of definite or possible stress-related ulceration: 1993, 6/693 (0.87%); 1994, 5/798 (0.63%); 1995, 6/670 (0.90%); 1996, 5/780 (0.64%). CONCLUSIONS: The incidence of endoscopically proven stress-related ulceration has remained unchanged over the past 4 years in our MICU despite significantly fewer patients receiving pharmacologic stress ulcer prophylaxis therapy.

Anti-Ulcer Agents↗
PubMed2004

Dipyridamole stress echocardiography and ultrasonic myocardial tissue characterization in predicting myocardial ischemia, in comparison with dipyridamole stress Tc-99m MIBI SPECT myocardial imaging.

The purpose of this study was to validate whether dipyridamole stress ultrasonic tissue characterization with cyclic variation of integrated backscatter (CVIBS) compared with dipyridamole stress echocardiography and dipyridamole stress Tc99m-MIBI SPECT myocardial perfusion scintigraphy could predict myocardial ischemia in patients with chronic coronary artery disease. Twenty patients (16 M, 4 F) who had coronary angiography for stable angina pectoris were included in the study. Mean age was 62 +/- 8 years. The left ventricle was divided into 16 segments. Regional wall motion analysis and CVIBS measurements were obtained from 16 myocardial segments at rest and after dipyridamole (0.84 mg/kg) infusion. After 10 minutes, Tc-99m MIBI (10 mCi) was injected and SPECT myocardial imaging was performed. After 3 hours, 25 mCi Tc-99m MIBI was reinjected and rest images were obtained. A total of 320 ventricular wall segments were evaluated. Two hundred and six ventricular wall segments were supplied by stenotic coronary arteries and 114 segments were supplied by normal coronary arteries. Dipyridamole stress Tc-99m MIBI SPECT studies showed abnormal myocardial perfusion in 176 segments and normal perfusion in 144 segments. Transient regional wall motion abnormality was detected in 116 segments. A significant decrease in CVIBS after dipyridamole stress was detected in 184 segments. The sensitivity and specificity of dipyridamole stress echocardiography, Tc-99m MIBI SPECT, and CVIBS were 56% and 100%, 85% and 92%, and 89% and 100%, respectively, compared with the results from coronary angiography. Dipyridamole stress ultrasonic tissue characterization with CVIBS may provide more sensitive detection of myocardial ischemia than dipyridamole stress echocardiography and may be as valuable as dipyridamole stress myocardial perfusion scintigraphy.

Aged↗
PubMed1996

Cardiovascular stress testing: a description of the various types of stress tests and indications for their use.

OBJECTIVE: To describe the various types of stress tests and to provide guidelines for selecting a specific test for an individual patient. MATERIAL AND METHODS: Myocardial perfusion imaging, radionuclide angiography, stress echocardiography, and cardiopulmonary exercise testing are described. The advantages and limitations of these techniques are reviewed and compared with those of standard treadmill exercise testing. The agents used for pharmacologic stress testing are discussed. RESULTS: Standard treadmill exercise testing is widely available and is less expensive than the imaging techniques. It is most accurate in patients with normal findings on a resting electrocardiogram who are not taking digoxin. In these patients, standard exercise electrocardiography is almost as accurate as the exercise imaging modalities for identifying those with left main or three-vessel coronary artery disease. Advantages of the stress imaging modalities in comparison with standard exercise electrocardiography include greater accuracy when the resting electrocardiogram shows abnormal findings, higher sensitivity, ability to localize and characterize the extent of myocardial ischemia, and direct measurement of other variables such as left ventricular function. These techniques must be performed carefully in experienced laboratories in order to provide accurate information. Published data are scant that directly compare one technique with another in the same set of patients. The nuclear cardiology techniques have been well validated for detecting left main and three-vessel coronary artery disease and for assessing prognosis. Myocardial perfusion imaging has been well validated for detecting ischemia in patients with abnormal left ventricular function at rest. In comparison with the nuclear cardiology techniques, stress echocardiography is less expensive and provides more ancillary information but has not been as well validated for assessment of severe coronary artery disease or prognosis. Cardiopulmonary exercise testing can be useful in selecting patients for cardiac transplantation and in assessing exertional dyspnea in selected patients. The most common application of pharmacologic stress testing is preoperative risk assessment of patients undergoing noncardiac operations. Pharmacologic stress testing should usually be reversed for patients who are unable to exercise adequately. CONCLUSION: Most patients with normal findings on a resting electrocardiogram who are not taking digoxin should undergo standard treadmill exercise testing for diagnostic and prognostic purposes. Most patients with abnormal findings on a resting electrocardiogram should undergo one of the stress imaging techniques. Selecting a specific stress imaging techniques. should depend primarily on local expertise with the various techniques and secondarily on the strengths and limitations of the techniques as they relate to the individual patient.

Algorithms↗
PubMed2005

The development of a race and gender-specific stress measure for African-American women: Jackson, Hogue, Phillips contextualized stress measure.

OBJECTIVE: Community-based research was conducted to develop an identity stress measure for African-American women. The aim of the investigation was to capture the voices of African-American women telling their experiences of stress and support and to have their voices inform the development of an identity stress measure representing the realities of being Black and female. In this paper, we describe the components of a race and gender-specific stress measure emerging from a multidisciplinary iterative process that employed qualitative and quantitative methods. METHOD: The research was initiated by focus groups and interviews where women were asked to share their experiences of stress and support. Four hundred seventy-four (474) African-American women from the metropolitan Atlanta area collaborated in the study by participating in one or more phases of the research. Content analysis of the qualitative data informed the development of a 71-item race and gender-specific stress measure for African-American women. The scale and a battery of validity measures (Spielburger Anger and Anxiety, John Henryism, and NHIS-depression) were administered twice over a 30-day period followed by group discussions and interviews. RESULTS: Content and factor analysis resulted in the development of six subscales: racism, burden, personal history, work, support/coping, and stress states. The measure has been validated with established measures of anger, anxiety, depression. Significant correlations were established for all of the stress subscales and measures of anger (trait anger, anger-in, anger-out, and anger expression). Findings indicate significant correlations for the burden subscale and anger-in (r=.33, <.01) and stress states and trait anxiety (r=.57, <.01).

Adaptation, Psychological↗
PubMed1995

Tendon response to tensile stress: an ultrastructural investigation of collagen:proteoglycan interactions in stressed tendon.

Tendons are parallel arrays of collagenous fibres which are specialised to resist and transmit tensile stresses. The response of tendon fibres to tensile stress is age-dependent and complex. Elastic elongation at low stress is accompanied by the disappearance of alternate light and dark bands seen in transmitted polarised light. This region of the stress/strain curve is associated with straightening of fibre 'crimps'. At higher stress, elongation is still elastic and reversible until break point is reached. This behaviour may be associated with straightening of a helical arrangement of collagen fibrils. In addition to the collagen fibrils, there are transverse and longitudinal proteoglycan filaments, many of which bridge and link between the fibrils. We have investigated the effect of various levels of stress from very low up to breaking point on the appearance of the proteoglycan filaments and their relationships with the collagen fibrils. Proteoglycan-collagen fibril interactions in rat and mouse tail and flexor digitorum tendons were visualised by Cupromeronic blue staining, applied to dissected fibres in the resting state and at stresses up to breaking. Proteoglycan filaments were seen to be orthogonally arranged in every D period, probably at the d band in mature tendons. In immature tendons proteoglycan filaments took up more varied orientations, but were mainly orthogonal or axially arranged with respect to the collagen fibrils. Both pictures appeared unchanged after application of stress of any level up to breaking point. Young tendons ruptured at lower stresses than mature tendons. It is suggested that PG bridges between collagen fibrils play a part in transmitting and resisting tensile stresses in tendons, contributing to the strength of the tissue.

Animals↗
PubMed1997

Management of post traumatic stress disorder using combat stress treatment principles--a case report.

Combat stress casualties are only generated by war. However, military psychiatrists need to acquire the experience and skills that they would need before they are ever faced with their first combat stress casualty. Non-combat post traumatic stress disorder patients present the best approximation to combat stress casualties. This case study demonstrates how combat stress treatment principles can be successfully applied to a case of non-combat post traumatic stress disorder patient. It is not the intention of this paper to demonstrate whether the combat stress management protocol is superior to other methods or protocols. Recommendations are made on methods to identify post traumatic stress disorder patients and how to seize every available opportunity to practise combat stress treatment principles.

Adult↗