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At least 991 records · Page 55Linked to original sources
PubMed2006

Oxidative stress, mitochondrial dysfunction, and stress signaling in Alzheimer's disease.

Although oxidative stress and mitochondrial dysfunction have been linked to neurodegenerative diseases such as Alzheimer's disease (AD), it remains unclear how mitochondrial oxidative stress may induce neuronal death. In a variety of tissues, cumulative oxidative stress, disrupted mitochondrial respiration, and mitochondrial damage are associated with, and may indeed promote cell death and degeneration. In this review, we examine current evidence supporting the involvement of mitochondria and mitochondrially generated stress signaling in AD and discuss potential implications for the mechanism of pathogenesis of this disease. Mitochondria are pivotal in controlling cell life and death not only by producing ATP, and sequestering calcium, but by also generating free radicals and serving as repositories for proteins which regulate the intrinsic apoptotic pathway. Perturbations in the physiological function of mitochondria inevitably disturb cell function, sensitize cells to neurotoxic insults and may initiate cell death, all significant phenomena in the pathogenesis of a number of neurodegenerative disorders including AD.

Alzheimer Disease↗
PubMed1975

Prediction of perceptual defense from experimental stress and susceptibility to stress as indicated by thematic apperception.

The present investigation tested the hypothesis advanced by J. Inglis (1961) that perceptual defense and perceptual vigilance result from an interaction between personality differences and degrees of experimental stress. The design, which controlled for questionable procedures used in previous studies, utilized 32 introverts and 32 extraverts, half male and half female, in an experiment with a visual recognition-task. Results indicated that under low-stress conditions introverts and extraverts identified by their response to a thematic apperception task react to threatening stimuli with perceptual defense and perceptual vigilance, respectively. Under high-stress conditions, type of avoidance activity reverses; extraverts react with perceptual defense and introverts with perceptual vigilance. It was suggested that, when both personality and stress variables are controlled, results of the perceptual defense paradigm are predictable and consistent, in support of Inglis' hypothesis.

Anxiety↗
PubMed2005

Simultaneous multiple stressors in the environment: physiological stress reactions, performance, and stress evaluation.

Interactive effects of two environmental stressors when simultaneous ly present, i.e., noise and crowding, were analyzed. Four experimental conditions with two intensities of stress for each stressor (high versus low) were created. The stressors were concurrently introduced in laboratory conditions and their effects analyzed using several methodological approaches. More intense and negative effects were expected when the two highest intensities of noise and crowding concurred. 40 people (20 men and 20 women) participated in a study with a 2 x 2 factorial design. Analysis showed an increase in the measures of hemodynamic, endocrine, and neuroendocrine values of participants after being exposed simultaneously to noise and crowding. Similarly, their performance on complex tasks decreased, and they reported a subjective increase in stress. Capacity to cope was indicated by a statistically significant lower mean on the Dimension of Stress scale, tolerance of frustration during the multiple stress condition.

Adolescent↗
PubMed2001

Persistent behavioural changes in rats following inescapable shock stress: a potential model of posttraumatic stress disorder.

Behavioural changes in rats two weeks after inescapable shock stress were studied using a shuttle-box task (active avoidance/escape). Rats exposed to inescapable shock stress two weeks beforehand showed more frequent avoidance responses and greater within-group variation in both avoidance response and general activity during the test than rats in a control group. General activity during an unstressful period (before starting the test) did not differ significantly between groups. This relatively prolonged increase in responsiveness to external stimuli in the stressful context may be a useful experimental model of posttraumatic stress disorder, especially in relation to hypervigilance.

Adaptation, Psychological↗
PubMed2006

Repetitive tensile stress to rat caudal vertebrae inducing cartilage formation in the spinal ligaments: a possible role of mechanical stress in the development of ossification of the spinal ligaments.

OBJECT: Mechanical stress has been considered one of the important factors in ossification of the spinal ligaments. According to previous clinical and in vitro studies, the accumulation of tensile stress to these ligaments may be responsible for ligament ossification. To elucidate the relationship between such mechanical stress and the development of ossification of the spinal ligaments, the authors established an animal experimental model in which the in vivo response of the spinal ligaments to direct repetitive tensile loading could be observed. METHODS: The caudal vertebrae of adult Wistar rats were studied. After creating a novel stimulating apparatus, cyclic tensile force was loaded to rat caudal spinal ligaments at 10 N in 600 to 1800 cycles per day for up to 2 weeks. The morphological responses were then evaluated histologically and immunohistochemically. After the loadings, ectopic cartilaginous formations surrounded by proliferating round cells were observed near the insertion of the spinal ligaments. Several areas of the cartilaginous tissue were accompanied by woven bone. Bone morphogenetic protein-2 expression was clearly observed in the cytoplasm of the proliferating round cells. The histological features of the rat spinal ligaments induced by the tensile loadings resembled those of spinal ligament ossification observed in humans. CONCLUSIONS: The findings obtained in the present study strongly suggest that repetitive tensile stress to the spinal ligaments is one of the important causes of ligament ossification in the spine.

Animals↗
PubMed1992

[Psychological stress and sexual behavior in male rats. II. Effect of psychological stress on dopamine and its metabolites in the critical brain areas mediating sexual behavior].

We have reported that sexual behavior of male rats is impaired by long-term psychological stress. We measured dopamine (DA) and its metabolites (3,4-dihydroxyphenylacetic acid, DOPAC, and homovanillic acid, HVA) in the brain of rats which were exposed to the long-term stress. Our experiment was focused on the medial preoptic area (MPOA), which is perhaps the single most critical area of the brain mediating sexual behavior, the amygdala, the substantia nigra, the striatum, the nucleus accumbens and the cortex. In the MPOA, dopamine, DOPAC, and HVA decreased; in the substantia nigra and amygdala, dopamine and HVA decreased; and in the striatum and nucleus accumbens only HVA decreased after long-term psychological stress. In the cortex, however, no evidence of change was recognized. These changes indicate low activity of dopamine neurons which have an important role in male sexual behavior. Therefore, we suspect that exposure of male rats to psychological stress leads to a decrease in the activity of dopamine neurons, especially in the MPOA, amygdala, and substantia nigra, impairing their sexual behavior.

3,4-Dihydroxyphenylacetic Acid↗
PubMedDate not supplied

Easing the burden of stress. A stress management program can help eldercare professionals cope.

Healthcare professionals in general, and those who care for the elderly in particular, must cope with a number of stressors in the working environment. Moreover, because care givers tend to put others' needs before their own, they often place an added burden of stress on themselves. Eldercare professionals must often forego the reward of finding a cure for their patients. In addition, the persons they care for can sometimes become overly dependent, depressed, unappreciative, self-centered, and demanding. The daily effort to deflect or diffuse this negative energy can take its toll on care givers, leading to coping deficiencies that themselves increase workplace tension and stress. Not only individuals, but entire departments can develop dysfunctional reactions to stress. To break this vicious cycle and improve workplace morale, facilities can implement stress management programs. As part of such a program, supervisors and managers identify stressors in the environment and suggest ways to alleviate or eliminate their effects. Once morale improves, coordinators should shift the program's focus to maintaining employee morale.

Adaptation, Psychological↗
PubMed1976

[Problems in the genetics of stress. II. Genetic analysis of endocrine gland weight in mice under normal conditions and during exposure to stress].

Relative weight of adrenals, thymus, hypophysis and gonads was studied in female mice after 21 days after parturition and in intact males. One group of females was stressed during pregnancy, and another group was intact. All these animals were a progeny of the full diallele cross of 4 inbred mice strains (BALB/c, C3H/He, C57BL/6, AKR/J). On the basis of analysis of general and specific combining ability the conclusion is drawn that the relative weight of the endocrine glands is inherited additively in females of both experimental groups. However, it was found that the size of additive genetic variation for these characters in the population of females, which had been stressed during their pregnancy was larger, than in the control population. A significant role of non-additive genes in the determination of these characters was observed in males. The degree of hypertrophy of adrenals and lysis of thymus in stressed females corresponded to their emotional reactivity. Significant genotypic correlations between the weight of some endocrine glands, on one hand, and the emotional reactivity and the rate of sexual maturation, on the other hand, were found in both experimental groups of females. In the stressed group these correlations were higher.

Adrenal Glands↗
PubMed2003

[Behavioral characteristics and stress reaction of the pituitary-adrenal system in prenatally stressed rats].

Mothers' stress was shown to considerably diminish the orienting-studying activity of male rats in the dioestrus stage, as well as enhancement of anxiety. In prenatally stressed male rats, on the contraty, the anxiety diminished while their behaviour in the open field tests remained practically unaltered. The prenatal stress affected the stressor response of the hypophysis-adrenal systems in both sexes. The data obtained suggest that the mothers' stress affects both behaviour and stressor response in male as well as female rats.

Animals↗
PubMed1992

Comparison of stress transmission in the IMZ implant system with polyoxymethylene or titanium intramobile element: a finite element stress analysis.

Using the finite element method, this study modeled a 4.0 x 13.0-mm IMZ implant, restored with a cast gold crown, to examine the influence of the polyoxymethylene (POM) intramobile element (IME) on the transmission of vertical and oblique forces. Stress concentrations in the bone and in components of the implant system were much greater under a 30-degree load than under an equal vertical load. Stress transmission to bone occurred chiefly in the crestal region, and these stresses were not reduced when the IME was modeled in POM rather than in titanium. Maximum stress concentrations occurred in the fastening screw.

Alveolar Process↗
PubMed1992

[Parental stress in mothers of preschool children: validation and Quebec norms for the Parental Stress Inventory].

The authors examine the metrological qualities of a French version of the Parenting Stress Index (Abidin, 1983; Loyd and Abidin, 1985) based on a sampling of 122 Québec mothers with a preschool child. Results show that the Parental Stress Inventory presents internal consistency indices that are equivalent to those obtained in the U.S. sampling. However, the samplings differ on seven out of 13 subscales, as well as concerning the scores obtained for the child's realm and the overall stress, Québec mothers show higher scores. The factorial analysis of the subscales supports the existence of a hierarchical structure composed of a general factor of parental stress and two specific factors: the realm of the child and the realm of the parent. The score relative to the realm of the parent varies according to the socioeconomic level and the marital status of the mother. The mother's age is negatively correlated with the score of the child's realm. The child's aggressiveness/hyperactivity level, as perceived by the teacher in a class situation, is positively correlated with the score of the subscale Difficulty to accept the child's characteristics and the subscale Distraction and hyperactivity of the child. The authors present benchmarks that were developed in order to take into account the noted differences between the Québec and U.S. samplings.

Adult↗
PubMed2005

Stress echocardiography in the evaluation of women presenting with chest pain syndrome: a randomized, prospective comparison with electrocardiographic stress testing.

OBJECTIVE: To evaluate the relative value of three stress testing modalities for establishing the presence of coronary artery disease in women presenting with chest pain. BACKGROUND: Echocardiographic testing modalities have the potential to be more effective than standard electrocardiographic stress testing (EST), but they require prospective evaluation. METHODS: Patients with no cardiac history and at least two cardiac risk factors were randomly assigned to one of three initial diagnostic strategies: treadmill EST (n=54), treadmill echocardiographic stress testing (ExE) (n=57) or dobutamine stress echocardiography (DSE) (n=47). Patients were followed prospectively for 28.1+/-14.2 months. The nature of the presenting chest pain was established clinically. RESULTS: Twelve patients (7.6%) were determined to have had cardiac chest pain, 128 patients (81.0%) received a diagnosis of noncardiac chest pain and 18 patients (11.4%) had indeterminate results. The echocardiographic testing modalities were associated with fewer indeterminate results than was EST (two of 104 [1.9%] versus 13 of 54 [24.1%]). All modalities were highly effective in excluding cardiac chest pain, with negative predictive values of 91.3%, 83.7% and 88.4%, respectively, for EST, DSE and ExE. The proportion of cases for which both definitive and accurate results were provided was 92.9% for DSE, 82.4% for ExE and 67.3% for EST. CONCLUSIONS: The results support the favourable prognosis of women presenting with chest pain syndrome and the reliability of negative results obtained with any of the testing modalities. Echocardiographic testing modalities are more likely than EST to provide both definitive and accurate results and would, therefore, seem to be the superior primary noninvasive testing modality in this patient population.

Adult↗
PubMed2005

[Is stress-induced analgesia a measure of stress severity?].

When comparing magnitudes of "behavioural despair" (duration of immobility) and stress-induced analgesia in the tail suspension test and cold water swim test with SHR and NMRI male mice. The results might depend on saline injection prior the test and on the fact that exposure to cold water in swim test was sufficient to alter the response patterns. The findings show that the main parameters are closely related to each other. Stress-induced analgesia seems to be a measure of stress as the stress becomes stronger analgesia changes in linear dependence, whereas duration of immobility has an invert U-shaped function.

Animals↗
PubMedDate not supplied

[Corticoliberin fragment CRF4-6 modifies rat behavior in opposite ways under stressing and non-stressing conditions].

The effects of tripeptide corticoliberin fragment CRF4-6 (icv; 6, 30, and 150 nmol/head) on behaviour of rats were investigated under non-stressing and stressing conditions. CRF4-6 activated rat behaviour under non-stressing conditions (home cage): the duration of locomotion and exploratory behaviour was increased whereas the duration of passive behaviour and sleep was decreased. On the other hand, CRF4-6 suppressed the rat exploratory behaviour under stressing conditions (elevated plus-maze): the duration of non-exploratory behaviour was increased; numbers of rearings and leanings out to open arms were reduced. All observed effects of the tripeptide CRF4-6 were dose-dependent. Behavioural effects of the tripeptide were similar to the well-known action of the whole corticoliberin molecule. Therefore we suggest that CRF4-6 is located in the active part of CRF or it can be a physiologically active corticoliberin derivative.

Animals↗
PubMedDate not supplied

[Kinetic properties of rat heart cathepsin D under normal conditions, during emotional-pain stress and in the post-stress period].

Cathepsin D preparations have been isolated from the heart of healthy animals and stress-surviving rats by the method of affine chromatography with the hemoglobin-biogel-P300 sorbent. To analysis of the obtained data permits concluding that acute stress stimulates activation of the catalytic function of cathepsin D in the heart. But the period after the stress accompanied by the consecutive proteolysis rate reduction, that can be explained, probably, by a change in enzyme conformation. The concentration of Ca2+ (10(-6), 10(-5) M) and cAMP (10(-7), 10(-6) M) exert a regulating influence on the cathepsin D activity in the heart in acute stress period and after it.

Animals↗
PubMed1991

[Stress in the hospital--stresses on nurses and physicians].

A questionnaire study was carried out with 891 physicians and nurses working in 54 different hospitals. The objectives were to assess the main stress situations at work and to find out, under which conditions the stress occurs. The results show that the most important stress situations concern the environmental working conditions and the identification with the patient. Physical complaints of the nurses and physicians exceed the scores of a matched norm sample. The main stress conditions are a low level of professional experience, working hours, working in rotating shifts and having to care for a great proportion of terminally ill patients. About 16% of the nurses and 9% of the physicians have to be considered severely distressed. The results shall serve a basis for providing support programs.

Adult↗
PubMed1990

[Daily stress, coping with stress and metabolic control in insulin dependent adult diabetics].

In accordance with previous research investigating adult insulin-dependent diabetics the present study supports evidence for a weak correlation between psychosocial stress and metabolic control (HbA1c). This relation, however, is becoming more substantial, if specific patterns of stress-reactions are taken into account. This is especially the case for a pattern represented by a short form of the SVF-subscale "emotional irritability" (Janke et al., 1984), and even better by the (inversely scored) FPI-K-scale "calmness" (Fahrenberg et al., 1978). Contrary to our expectations a high amount of emotional irritability was leading to a more favorable metabolic control, especially in the case of high psychosocial stress. It is suggested that positive attention-directed and motivating functions of emotional stress-reactions may in the long run compensate or even exceed their short-lived debilitating metabolic effects.

Adaptation, Psychological↗
PubMed1988

High-G stress and orientational stress: physiologic effects of aerial maneuvering.

G stress can readily incapacitate pilots of modern fighter aircraft and result in mishaps due to G-induced loss of consciousness (GLC). The physiologic effects of high-G stress, including decreased head-level blood pressure due to hydrostatic pressure drop and decreased cardiac output due to inadequate venous return, result in the symptoms of visual loss and GLC. The body's primary natural defenses against the effects of G stress in flight, i.e., the neural tissue energy reserve and the cardiovascular baroceptor reflexes, determine the characteristic shape of the G-time tolerance curve, which is presented. Means of raising G tolerance fall into three categories: mechanical, physiological, and educational. Mechanical means include anti-G suits and valves, assisted positive-pressure breathing (APPB) systems, and special seats in which the seatback is reclined and/or the pilot's legs are elevated. Physiological means include frequent exposure to G stress, physical conditioning (weight training and moderate aerobic conditioning), selection of pilots for high natural tolerance, and performance of a vigorous and efficient anti-G straining maneuver. Educational means include briefings on methods of enhancing tolerance, and high-G training in a centrifuge to allow the pilot to perfect his anti-G straining maneuver. An improved anti-G valve, physical conditioning, high-G awareness briefings, and centrifuge training are now being applied in efforts to prevent GLC in current fighter aircraft. Future generations of even more maneuverable aircraft will probably necessitate the use of APPB, pilot selection, and high-G seats for protection of pilots from the effect of sustained high G forces.

Aerospace Medicine↗