SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The general adaptation syndrome is discussed on the light of recent discoveries on hypothalamic peptides and of their possible influence in survival and in induction of diseases. The problem of stress in alcoholism is reviewed. The author ends with a short souvenir of Hans Selye.
A variety and rate of non-cancer diseases occurred in humans as a result of chronic exposure to ionizing radiation or to electromagnetic radiation (EMR) of high and superhigh frequency have been compared. The intensity of EMR was slightly higher than a sanitary standard for population. A risk of health impairments in workers having occupational exposure to EMR was assessed on the basis of Selie's concept of development of non-specific reaction of the body to chronic stress factors (general adaptation syndrome), models of changes in the body compensatory reserves and calculations of radiation risk after severe and chronic exposure to ionizing radiation.
The authors conducted two series of experiments on 144 mice of BAL/c and C57B1 line. It was established that in autotransplantation submicroscopical changes developing in somatotropinocytes are typical of stressor situation and reflect various phases of general adaptation syndrome. An increase in the number of cells in the phase of active proteinic synthesis and degranulation is observed in allotransplantation in inductive phase of immunogenesis. Before rejection the number of cells in the phase of active proteinic synthesis is decreased, and in degranulation phase--is increased.
The object of this work was to establish whether induced stress leads to morphological changes in the sublingual and submaxillary glands of rats. General adaptation syndrome (S.G.A.) was induced in 25 young adult male Wistar rats through cold and immobilization. The animals were killed 48 hrs. and 10 days after stressor (E.A.) application. To verify stress condition, the adrenales were weighed and plasmatic corticosterone were carried out. The sublingual and submaxillary glands were dissected, fixed in buffered formol and stained with H.E. The results histology indicate that the submaxillary is more sensitive to cold than the sublingual, while the reverse holds true form immobilization.
The General Adaptation Syndrome is characterized by three stages: Alarm Reaction - Adaptation - Exhaustion. Results of animal experiments and clinical observations indicate that both central nervous and peripheral systemic reactions to acute stress - e.g. noise - can be accentuated by magnesium deficiency and reduced by mild hypermagnesemia, respectively. Concerning long term suboptimal magnesium supply, experimental data indicate that a stage of adaptation might be achieved during a certain period of time, preceded and followed by stages of markedly decreased resistance.U
To maintain their body integrity when aggressed, living organisms use a series of genetic and metabolic events constituting the stress response. Experiments carried out on man and superior vertebrates have shown that the stress response can be considered as a general adaptative syndrome. It constitutes one of the key elements of the defense system and can schematically be decomposed as an immediate response related to the release of preformed or formed de novo cytotoxic cell mediators and a delayed response with genomic interactions and induced protein synthesis. In invertebrates, experiments were essentially aimed at study of cytotoxic secreted agents during immediate response. However, the presence of cytokine like agents, NO-synthases and heat shock proteins were also found in molluscs, insects, annelids and echinoderrns. In marine bivalvia, informations on stress response are scarce and ftagmentary and, to the best of our knowledge, no coherent synthesis was carried out. The aim of the present work is to collect up to date results in this field and to carry out a comparative analysis of defense mechanisms known in vertebrates.
A concept of extreme state as a specific physiological category different from the general adaptation syndrome (stress-response), is presented. The extreme state occurs in case of a functional supertask when the price of urgent adaptation of the organism can involve life-threatening. The author presents a bio-economic approach to analysis of redistribution of the energy balance for maintenance of the organism's functioning in a critical situation, and suggests some ways of scientific-practical realisation of this approach.
The literary data and own results concerning the stages of free radical lipid oxidation inhibition during the adaptation of animals to stress are reviewed. Using the chronic stress models such as immobilization, experimental neurosis, it has been shown, that in general adaptation syndrome the stage of permanent adaptation to stress corresponds to a permanent inhibition of free radical processes in animal tissues. This stage is accompanied by the activation of superoxide radical scavenging and corresponding changes of lipid composition. similar results are obtained on the model of the development of permanent compensation processes after brain injury. Studying the acute stress it has been found, that during first minutes the inhibition of lipid peroxidation which precedes its further activation takes place. This stage corresponds to the realization of urgent adaptation phase to stress. The role of inhibition of free radical processes in mechanisms of urgent and permanent adaptation to stress is under discussion.
An overview of the main problems and misconceptions in the clinical application and theoretic evaluation of the stress concept reveals that the same 10 problems appear to cause the greatest difficulties in its application, irrespective of the specialty in which it is used: (1) the correct definition of stress, stressors and the general adaptation syndrome; (2) the concept of nonspecificity in biology and medicine; (3) the conditioning of stress responses by diverse endogenous (mainly genetically determined) and exogenous (environmental) factors; (4) the relation between the genral and the local adaptation syndromes; (5) the difference between direct and indirect pathogens; (6) the definition of the morbid lesions in whose pathogenesis stress plays a particularly prominent role--the so-called diseases of adaptation; (7) the role of genetics versus that of factors under voluntary self-control in mastering biologic stress; (8) the mode of action of syntoxic and catatoxic hormones, drugs and behavioural attitudes; (9) the so-called first mediator of the stress response, which carries the message that a state of stress exists from the directly affected area to the neurohormonal regulatory centres; and (10) the prophylaxis and treatment of stress-induced damage by pharmacologic and behavioural techniques.
The appropriate literature has been reviewed for the purpose of defining the phenomenon of stress in lactating dairy cattle, establishing a baseline concept of lactation stress and emphasizing the most significant aspects of the natural mammary defence mechanisms. Data on the general adaptation syndrome (GAS) make it clear that stress is essentially the rate of wear and tear of the biological system affected by a stressor either eliciting stress of the organism as a whole or partly so. Owing to the variety of stressors which may affect the dairy cow at physiological and pathological levels, a definition of stress in the broad sense is indicated. This is essential from the point of view of the anti-homeostatic effects (metabolic and immunological) of lactation stress, aggravated by anti-homeostatic effects elicited by superimposed other types of stress (e.g. heat stress). The lactating cow, as a ruminant in a state of sustained stress, requires a special profile of hormonal mediators. In high yielding cows, for example, acute and sustained heat stress promotes increased activities of prolactin, progesterone and catecholamines. Compared with the mainly glycogenic/glycogenolytic metabolism of non-ruminant mammals, the lipogenic/lipolytic and glycogenic/glycogenolytic metabolism of the dairy cow depends on hormonal mediators which differ from those of the former not so much in their nature but in their magnitude and ratios. Stressors induce the development of GAS reactions in the dairy cow. These enable the cow to create and maintain homeostasis of its integrated 3 main physio-pathological systems and thus to endure the stressor(s). The cow's compensating adjustments to a stressor are therefore the effects of stress. This means that natural lactation is the effect of the lactation stress induced by the cow's progeny (i.e. the natural lactation stressor). Artificial lactation stressors (e.g. removal of milk by hand and machine) may affect the lactation stress in magnitude but not necessarily in nature. Likewise, a range of behavioural, physiological, lactational and lacteal changes related to other stressors are the effects of different types of stress. Lactation stress, like other types of stress, shows 3 stages of development, i.e., an overcompensating alarm phase (= lactogenesis), resistance phase (= galactopoiesis) and exhaustion phase (= regression). They facilitate adjustments of the cow's homeostasis from the level of involutional homeostasis (= no lactational activity) to that of lactational homeostasis. Like other tissues in a state of stress, the lactating mammary epithelium requires a greatly increased supply of glucose.(ABSTRACT TRUNCATED AT 400 WORDS)
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.