Stress and illness.
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Adaptation, Psychological↗
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Stress-induced arrhythmic disease of the heart--Part I.
This review deals with the following principal concepts: (1) Heart injuries in single severe stress episodes manifested primarily in disturbances of membrane lipid bilayer, sarcolemmal Na, K-pump, and sarcoplasmic Ca-pump with concurrent limited disturbances of the heart energy supply, namely, of the creatine kinase and glycolysis systems. These disturbances cause small focal myocardial lesions and reduce cardiac electrical stability: the fibrillation threshold falls and ectopic activity increases. In repeated stress, this damage, localized mainly in the richly innervated conduction system, accumulates to cause even more pronounced disturbances of electrical stability and severe arrhythmias. (2) Severe stress and beta-adrenergic effects on the heart regularly result in coronary vasodilation and increased coronary blood flow. However, the entire primary complex of stress-induced injuries and disturbances of the heart's electrical stability occurs despite the increased coronary blood flow. Thus, beta-adrenergic stress-induced injuries may indeed develop as primary stress damage to cardiomyocytes without any relation to ischemia. (3) The main factor determining high vulnerability or, on the contrary, resistance of the heart to stress is the state of stress-limiting systems, namely, the opioidergic, GABAergic, cholinergic, adenosinergic, and other systems. Activation of these systems by adaptation to repeated stress or other factors prevents serious injuries to the heart in severe stress. Conversely, genetically determined or acquired dysfunction of these systems predisposes to severe arrhythmias and sudden death. Thus, in stress-induced arrhythmic disease as well as in ischemic heart disease, the main pathogenetic links are outside the heart, but they differ from those observed in ischemia. (4) The clinical picture of stress-induced arrhythmic disease, that is, alterations in electrocardiogram, coronarogram, and patient responses to stress, physical loads, and tranquilizers differ, as do pathologic alterations in the heart. These differences are summarized at the end of this review.
Animals↗
Individual differences and the stress response: studies of a wild primate.
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Adrenal Cortex↗
[Blood lipid and blood glucose changes during single, multiple and repeated stress].
As soon as various stressors exceed specific thresholds they induce marked metabolic changes in the organism. In a number of studies these facts have been verified experimentally. In our investigations we were able to demonstrate that the pattern of stress-induced changes differs after single and multiple stress exposures and that metoblic alterations in repeated stress situations are modified by habituative and adaptative processes respectively. Stress-induced metabolic mechanisms differently develop for blood lipid fractions and blood glucose. The described mechanisms are explained according to the functions of these blood parameters during stress exposures. The differential analysis of these alterations may be important for the prevention of stress-induced metabolic disorders.
Adult↗
Neurotransmitters and stress.
In this article definitions of stress and distress are proposed and the relationships between stress and activities of neurohormonal systems explored. The idea is developed that stress is a condition where expectations--whether genetically programmed, established by prior learning, or deduced from circumstances--do not match the current or anticipated perceptions of the internal or external environment, and this discrepancy between what is observed or sensed and what is expected or programmed elicits patterned, compensatory responses. Distress is viewed here as a form of stress characterized by specific behavioral and autonomic communicated signs, pituitary-adrenocortical and sympathoadrenomedullary activation, and a negative experience that motivates escape or avoidance. During stress, many body systems--including the sympathoadrenal, parasympathetic, and hormonal homeostatic systems--are activated or inhibited in primitively specific patterns regulated by physiological, biochemical, and psychological homeostats. Many of these patterns, which are at least partly inherited, can be understood teleologically on the basis of preservation of the internal environmental and natural selection in evolution.
Animals↗
Mercury toxicity as compared to adrenocorticotropin-induced physiological stress in the chicken.
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Adrenocorticotropic Hormone↗
[The significance of physical activity on the physiological stress reaction].
The extent of physical activity and the dynamic performance capacity show an inverse relationship to cardiovascular mortality, independent of the influence of other risk factors, but the underlying mechanism remains uncertain. Most concepts assume that the aerobic capacity of the peripheral musculature is increased by training, and thus improved cardiocirculatory regulation and especially a more favorable stress reaction pattern are attained. This adaptation is essentially an inverse adaptation mechanism as in established cardiocirculatory insufficiency. Based on an extended stress concept, it can be seen that training effects, especially in autonomic circulatory regulation, occur under physiological conditions to a lower degree in the renin-angiotensin-aldosterone system and in inflammatory reaction. The training effects depend on the form of exercise, the baseline condition, the extent of training, and genetic predisposition. It can be particularly demonstrated when the aerobic capacity has been sufficiently enlarged in an adequate proportion of the peripheral musculature. To what extent and under what conditions these training effects can be used under the pathophysiological conditions of established cardiocirculatory insufficiency is presently under investigation.
Adaptation, Physiological↗
Changes in the plasma electrolytes and metabolites of the rat following acute exposure to sodium fluoride and strontium chloride.
Acute exposure of rats to strontium or fluoride by i.p. injection of sodium fluoride or strontium chloride resulted in a systemic response in which changes occurred in the plasma electrolytes and metabolites. Strontium resulted in a rapid but temporary hypercalcaemia while fluoride produced a temporary hypocalcaemia. There was no significant hypophosphataemia after fluoride and only a transient hypophosphataemia with strontium. There was some indication of kidney damage and a general stress response following fluoride injection. These results do not support the hypothesis that interglobular dentine is associated with hypophosphataemia or hypoplastic enamel with hypocalcaemia and are in conflict with the observation that the formation of interglobular dentine following the injection of lead acetate is associated with hyperphosphataemia and hypercalcaemia.
Amelogenesis↗
The interrelationship of stress and degenerative diseases.
The following hypothesis has been proposed: Stressors--environmental and/or nutritional--can cause functional disorders. Functional disorders are abnormal neurology, endocrinology, and kinesiology without underlying organic pathology. The malfunction of these three systems is a major factor in the pathogenesis of systemic and dental degenerative diseases. Dental structural aberrations (malocclusion) can be perceived by the brain as major, 24-hour-a-day stressor agents, thus adding substantially to the total distress of the patient. In this manner, malocclusion becomes a significant factor in the pathogenesis of degenerative diseases. Under this hypothesis, malocclusion is the result of functional disorders, not genetics. Treatment of the entire patient cannot be overemphasized. The following suggestions can be made: 1. Conventional dental restorative treatment should be supplemented with nutritional therapy to eliminate nutrition as a distress agent. 2. Dental pathosis should be eliminated for optimum systemic health as well as preservation of the dentition.
Environment↗
Activation of the hypothalamus-pituitary-adrenal axis by bacterial endotoxins: routes and intermediate signals.
Peripheral administration of endotoxin induces brain-mediated responses, including activation of the hypothalamus-pituitary-adrenal (HPA) axis and changes in thermoregulation. This paper reviews the mechanisms by which endotoxin affects these responses. The effects on thermoregulation are complex and include macrophage-dependent hyperthermic and hypothermic responses. Low doses of endotoxin, given IP, activate peripheral macrophages to produce interleukin (IL)-1 beta, which enters the circulation and acts as a hormonal signal. IL-1 may pass fenestrated endothelium in the median eminence to stimulate corticotropin-releasing hormone (CRH) secretion from the CRH nerve-terminals. In addition, IL-1 may activate brain endothelial cells to produce IL-1, IL-6, prostaglandins, etc., and secrete these substances into the brain. By paracrine actions, these substances may affect neurons (e.g., CRH neurons) or act on microglial cells, which show IL-1-induced IL-1 production and therefore amplify and prolong the intracerebral IL-1 signal. In contrast, high doses of endotoxin given i.v. may directly stimulate endothelial cells to produce IL-1, IL-6, and prostaglandin-E2 (PGE2) and thereby activate the HPA axis in a macrophage-independent manner.
Adrenocorticotropic Hormone↗
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↗
Alterations in cholinergic and non-cholinergic neurotransmitter receptor densities in transgenic Tg2576 mouse brain with beta-amyloid plaque pathology.
Cholinergic deficits in Alzheimer's disease are accompanied by a number of alterations in other transmitter systems including glutamate, noradrenaline and serotonin, suggesting the involvement also of other neurotransmitter systems in the pathogenesis of the disease. To address the question whether beta-amyloid may contribute to these deficits, brain tissue from transgenic Tg2576 mice with Alzheimer plaque pathology at ages of 5 (still no significant plaque load) and 17 months (moderate to high cortical beta-amyloid plaque load) were examined for a number of cholinergic and non-cholinergic markers. Transgenic mice with no significant plaque load demonstrated reduced hemicholinium-3 (HCh-3) binding to choline uptake sites in anterior brain regions as compared to non-transgenic littermates, while in aged transgenic mice with high number of plaque deposits decreased HCh-3 binding levels were accompanied by increased vesicular acetylcholine transporter binding in selected cortical brain regions. In aged transgenic mice GABA(A), NMDA, AMPA, kainate, and beta-adrenergic as well 5-HT(1A)- and 5-HT(2A)-receptor binding levels were hardly affected, whereas alpha(1)- and alpha(2)-adrenoceptor binding was increased in selected cerebral cortical regions as compared to non-transgenic littermates. The development of changes in both cholinergic and non-cholinergic markers in transgenic Tg2576 mouse brain already before the onset of progressive plaque deposition provides in vivo evidence of a modulatory role of soluble beta-amyloid on cortical neurotransmission and may be referred to the deficits in learning and memory observed in these mice also before significant plaque load.
Acetylcholine↗
Reduced mechanical load decreases the density, stiffness, and strength of cancellous bone of the mandibular condyle.
OBJECTIVE: To investigate the influence of decreased mechanical loading on the density and mechanical properties of the cancellous bone of the human mandibular condyle. DESIGN: Destructive compressive mechanical tests were performed on cancellous bone specimens.Background. Reduced masticatory function in edentate people leads to a reduction of forces acting on the mandible. As bone reacts to its mechanical environment a change in its material properties can be expected. METHODS: Cylindrical bone specimens were obtained from dentate and edentate embalmed cadavers. Mechanical parameters were determined in the axial and in the transverse directions. Subsequently, density parameters were determined according to a method based on Archimedes' principle. RESULTS: The apparent density and volume fraction of the bone were about 18% lower in the edentate group; no age-related effect on density was found. The decrease of bone in the edentate group was associated with a lower stiffness and strength (about 22% and 28%, respectively). The ultimate strain, however, did not differ between the two groups. Both groups had similar mechanical anisotropy; in axial loading the bone was stiffer and stronger than in transverse loading. CONCLUSIONS: Reduced mechanical load had affected the density and herewith the mechanical properties of condylar cancellous bone, but not its anisotropy. RELEVANCE: The change in material properties of the cancellous bone after loss of teeth indicate that the mandibular condyle is sensitive for changes in its mechanical environment. Therefore, changes in mechanical loading of the condyle have to be accounted for in surgical procedures of the mandible.
Aged↗
Mechanical properties of nasal fascia and periosteum.
OBJECTIVE: To determine under which layer the silicone implants should be inserted into, the biomechanical properties of fascia and periosteum were investigated. DESIGN: Biomechanical testing of cadaveric tissues. BACKGROUND: In silicone augmentation rhinoplasty, most complications are closely related to the depth of implant and the mechanical character of the tissue surrounding the implant. METHODS: Biomechanical properties of human nasal periosteum and fascia were studied, including tensile strength, stress-strain relationship and stress relaxation under uniaxial elongation.Result. Although with less failure strain, the periosteum has more tensile strength than fascia. The slope of the linear part of stress-strain curve of the periosteum is bigger than that of fascia, which indicates the periosteum is stiffer than fascia. The stress-relaxation slope of periosteum is smaller than that of fascia. CONCLUSION: In the view of biomechanics, the periosteum is thicker, stronger and stiffer than fascia. Under periosteum the silicone implants are easier to be fixed at desired position, thus periosteum is more suitable for covering silicone implants. RELEVANCE: The periosteum is more suitable than fascia for covering silicone implants in augmentation rhinoplasty.
Adolescent↗
The stress response and autoimmunoregulation.
Using the recent burgeoning of information on how the stress response systems interact, and combining this with advances in our understanding of neuroimmune communication, a proposed neuroendocrine-neuroimmune stress response system incorporating autoimmunoregulation is reviewed. The study of immunocyte behavior in certain clinical conditions associated with a variant stress response may help illuminate the functioning of the neuroendocrine-neuroimmune stress response system.
Animals↗
Vestibular function and sensory interaction in altered gravity.
The effects of weightlessness on vestibular function have been studied since the beginning of manned spaceflight. The results of these studies have been highly variable and to some extent even contradictory, which makes it difficult to draw unambiguous conclusions. This variability is probably due to at least three factors: (1) individual differences in the adaptive process, (2) non-standardized experimental methods and conditions, (3) a lack of integrated experiments. For this reason, we have used a single integrated approach with a specially developed battery of tests. The results thus obtained for 21 cosmonauts on short- and long-term flights are reviewed here, and discussed in the light of the results obtained by others. Changes in the operation of the vestibular system and in all functions based on vestibular afferent input are commonly observed in spaceflight. These changes are characteristic for the process of adaptation and re-adaptation to altered gravity. They occur in a high proportion of persons exposed to such conditions, although there are individual differences with regard to severity, nature, time and duration of occurrence, and the dynamics of the process. Analysis of the observations in a large number of cosmonauts has permitted to distinguish three types of adaptation of the system to altered gravity. The first type of adaptation is characterized by a strong response to any stimulus during the initial adaptation period. The second type of adaptation is characterized by responses that are drastically decreased or even absent. The third type of adaptation is distinguished by the selective response of the sensory system to certain types of stimulation only. After long-term missions the process of re-adaptation usually takes a more severe course than the earlier process of adaptation to microgravity. Both adaptation and re-adaptation follow an undulating course, in which adaptation and re-adaptation are alternating. This is most conspicuous during long-term flights, and it suggests that in the initial stage of adaptation to weightlessness the vestibular input plays a dominant role, while at the end of the adaptation process the visual input prevails.
Eye Movements↗
[Quality of life despite illness. How does diabetes type 2 change quality of life of patients and how can it be modified?].
UNLABELLED: The research-question, posed in this study, was: How does diabetes type 2 change the quality of life of the persons involved and how can this be influenced? As these perceptions are subjective a qualitative approach was chosen. The interpretations of the persons involved were collected by using both a focus group discussion and individual interviews. CONCLUSION: The quality of life of the persons with diabetes type 2 questioned in this study, was altered especially in the functional health area. The concepts named here, were house-keeping, nutrition and mobility. But also the area of spare-time-management with concepts as hobbies and holidays, as well as the area of control with the concept of self-control, were named as being compromised by the illness. Information was recognized as a very important influencing factor. Information can positively influence the strength of the impact of diabetes type 2 on the quality of life.
Activities of Daily Living↗
[Value of brain ultrasound studies of newborn infants for prediction of neurological development in the 1st year of life].
BACKGROUND: Recent advances in perinatology have been associated with a decrease in perinatal mortality. However, nowadays detailed assessments are of major importance for accurate prediction of neurologic development of extreme low birth weight infants and term infants with severely disturbed postnatal adaptation. This study examined the role of cranial ultrasound for the prediction of developmental progress during the first year of life. PATIENTS AND METHODS: Fifty nine infants with gestational age less than 33. weeks and fifty seven infants with gestational age above 32. weeks were studied. Each infant was classified as normal, suspect or abnormal using cranial ultrasound and a specialized scoring system during the first days and twelve month of life. Repeated structured neurological examination were carried out during the first year of corrected age. By statistical analysis was investigated the correlation between the degree of ultrasound abnormalities and neurological outcome of neonates of both different gestational age groups. RESULTS: We diagnosed the same share of pathological ultrasound scans in both groups within the first days of life. In contrast there were remarkable differences concerning the results of sonographic investigation at the end of the first year of life. We demonstrated a significant higher incidence of abnormal findings in neonates with a gestational age less than 33 weeks at this point of time. The neurological progress of neonates of both groups was significantly disturbed in cases of major sonographic abnormalities. Cases of mild or moderate ultrasound abnormalities were significantly associated with a poor neurologic outcome only in neonates with a gestational age less than 33 weeks. By statistical analysis we proved a significant value of cranial ultrasound for prediction of neurological development of preterm neonates with gestational age less than 33 weeks. The certainty prediction of neurodevelopmental sequelae in neonates with gestational age above 32 weeks was associated with major sonographic abnormalities but not with mild or moderate sonographic pathology. CONCLUSION: The prognostic accuracy of ultrasound scans performed in the first week of life is important for preterm neonates with gestational age less than 33 weeks. In neonates with gestational age above 32 weeks we revealed no significant predictive value of the method. This limits the value of this technique in this patients as a reliable method for recognising of the infants with the need of early rehabilitation.
Brain Damage, Chronic↗