Physical Stress Conditions Research Articles

Ｂｒｕｘｉｓｍの研究 Ｂｒｕｘｉｓｍ自覚者と無自覚者の睡眠中のＢｒｕｘｉｓｍの観察

Bruxism has been considered to be one of the most important factors in accelerating the progression of established periodontal lesions. However the objective diagnostic method has not yet been established. At present, diagnosing bruxism might mainly be dependent on interview. The purpose of this study was to compare and analyze the differences in frequency and duration of bruxism between a group of patients conscious of the problem and a group not conscious of bruxism. After interviewing, the subjects were divided into two groups; 1) group A consisted of 8 subjects who were conscious of bruxism and 2) group B of 8 subjects who were not conscious of bruxism. The frequencies and durations of muscle activity during sleep at night were compared between groups A and B using EMG with a telemetric method. In the one-night observation, muscle activity supposed to be bruxism was observed in both groups. Significant differences in frequencies of muscle activity were not found between the two groups. A similar result was obtained in the durations of muscle activity. In a seven-day observation, muscle activity was seen in all three volunteers, although marked differences were not found among them. A long duration of muscle activity was found under conditions of physical or mental stress. The results of this study showed the difficulty of diagnosing bruxism by interview and the necessity of an objective method.

The dynamics of hypertension—An overview: Present practices, new possibilities, and new approaches

Contemporary clinical evaluation of hypertensive patients must include observations encompassing the impact of environment, behavior, and sociologic factors on metabolism and physiology. As evidenced by animal and human studies, catecholamines are an important mediator between psychologic factors and cardiovascular physiology, but direct measurement of catecholamine levels has not proved useful. Measurement of hemodynamic variables—blood pressure, heart rate, and stroke volume—during standardized psychophysiologic challenges is advocated. With low-challenge standardized stressors that include α- and β-adrenergic stimuli, inappropriate reactors can be classified according to whether blood pressure is elevated primarily by cardiac output, total systemic resistance, or a combination of both. Hypertensive patients can be similarly distinguished, and medication can then be custom-tallored to the underlying physiology. Extensive laboratory and clinical evidence points to significant interrelationships between the central nervous system and the cardiovascular system. Furthermore, cardiovascular physiologic and metabolic perturbances are distinctly different under conditions of mental vs physical stress. Most clinical testing assesses physical performance whereas the real-life challenges of today are primarily mental.

Silent myocardial ischemia: Hemodynamic changes during dynamic exercise in patients with proven coronary artery disease despite absence of angina pectoris

The hemodynamic changes during exercise occurring in 36 patients with proven coronary artery disease (10 without and 26 with previous myocardial infarction) who tolerated the stress test without angina were analyzed and compared with changes observed in a control group of 36 carefully matched patients whose exercise was limited by angina. All patients were exercised to the same extent, reaching a similar rate-pressure product at the end of the stress test (19,508 +/- 4,828 [SD] versus 19,247 +/- 4,117 beats/min X mm Hg [NS] in the study and control groups without prior infarction, and 19,665 +/- 3,950 versus 17,701 +/- 4,600 beats/min X mm Hg [NS] in the respective groups with infarction). In all groups left ventricular end-diastolic pressure increased from rest to exercise (from 18 +/- 4 to 36 +/- 11 and from 13 +/- 5 to 29 +/- 9 mm Hg, respectively, in the study and control groups without prior infarction and from 17 +/- 7 to 32 +/- 13 and from 19 +/- 7 to 36 +/- 9 mm Hg in the respective groups with prior infarction). Left ventricular ejection fraction decreased (from 59 +/- 7 to 50 +/- 15 and from 60 +/- 4 to 52 +/- 9% in the study and control groups without prior infarction and from 54 +/- 9 to 47 +/- 10 and 55 +/- 9 to 50 +/- 4% in the respective groups with prior infarction). Whereas the changes from rest to exercise were highly significant within each group, no significant differences were noted between the corresponding groups. Regional de novo hypokinesia appeared in all patients without prior infarction and in 25 and 22 patients, respectively, of the groups with prior infarction. Thus, under similar physical stress conditions, comparable hemodynamic changes indicative of ischemia are observed in patients with significant coronary artery lesions with or without previous myocardial infarction irrespective of the occurrence of angina. Therefore, angina pectoris cannot be considered a prerequisite for hemodynamically significant ischemia during exertion.

Agriculture group symposium plant growth under physical stress conditions

Journal of the Science of Food and AgricultureVolume 34, Issue 9 p. 943-950 Symposium Agriculture group symposium plant growth under physical stress conditions First published: September 1983 https://doi.org/10.1002/jsfa.2740340908AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume34, Issue9September 1983Pages 943-950 RelatedInformation

Somatic and Non‐Somatic Influences on the Heart: Hemodynamic Changes

ABSTRACTHemodynamic changes in response to two different stressors were obtained and compared in order to determine whether non‐somatic influences on the cardiovascular system were similar to somatic influences regardless of the metabolic requirements. Ten subjects participated in three different treatment conditions: a) pre‐performance anxiety (a realistic psychological stress condition), b) mild exercise (the physical stress condition), and c) a control (no stress condition). The exercise levels were assigned to elicit heart rates equivalent to those observed during the pre‐performance anxiety condition. The cardiac index (CI) for both stressors was significantly increased above control values and even though the exercise condition had a higher predicted metabolic requirement, similar CI values were found in 8 out of 10 subjects. Two subjects classified as labile hypertensive responded with a greater cardiovascular reactivity to the psychological stress than to the physical stress. It appeared that the psychological stress condition evoked a cardiovascular response that was excessive for the metabolic requirements.

The role of aspirin in gastric ulceration . Some factors involved in the development of gastric mucosal damage induced by aspirin in rats exposed to various stress conditions.

The gastric irritant effects of aspirin were studied in rats treated with a variety of physical and "disease" (inflammatory) stress conditions (which may mimic responses to some stress states encountered clinically) with the object of establishing whether these stress states increase the susceptibility of the gastric mucosa to the potentially ulcerogenic actions of aspirin. While exposure to physical (eg, cold) stress conditions markedly increased the sensitivity of the gastric mucosa to aspirin, exposure to various disease stressors (eg, adjuvant arthritis, acute pain, or paw inflammation) did not appreciably affect the mucosal sensitivity to this drug. Attempts were made to determine the mechanisms of the physical stress plus aspirin interaction by use of pharmacological agents. The results suggest a major involvement of the parasympathetic-vagal, sympathetic, and histamine-producing systems, but not the adrenocortical axis, in this model of gastric ulcerogenesis. No differences were observed in the mucosal uptake of [14C]aspirin, showing that accelerated uptake of the drug is not a factor in the development of gastric ulceration.

Effects of carbon dioxide and nitrogen on the secretion of parabenzoquinones by Tribolium castaneum (Herbst)

Abstract Tribolium castaneum (Herbst) is known to expel a defense secretion of parabenzoquinones under certain conditions of physical and thermal stress. Experiments were undertaken to determine the effects of a possible chemical stress on T. castaneum by subjecting adults to increased percentages of Carbon dioxide or Nitrogen in dry air. Carbon dioxide percentages from 40 to 96 per cent caused the beetles to secrete considerable quantities of p -benzoquinones These secretions did not occur in air containing increased percentages of N 2 . The data indicate that T. castaneum secretes p -benzoquinones only in a condition of partial narcosis. Results of this study are pertinent to current concepts in fumigation of grain storage containers which advocate purging with CO 2 or N 2 .

Role of L-Glutamate in the Tolerance of Osmotic Stress by <i>Escherichia coli</i>

Studies on the cellular response to conditions of physical or chemical stress have played a very significant role in diverse areas of biology. The present investigation aims at determining concentrations of NaCl that are stressful for environmental and clinical strains of Escherichia coli and to investigate the effect of L-glutamate to counteract such stressful conditions. It was observed that growth of environmental, clinical and reference strains could be stressed by a NaCl concentration of 0.9 M. Growth decreased under conditions of stress as opposed to that without added NaCl. Clinical isolates showed much higher resistance than environmental strains to osmotic stress. Glutamate had a significant effect in overcoming osmotic stress under laboratory conditions. This was indicated by increased growth in the presence of glutamate (15 mM) compared to that occurred at 0.9 M NaCl without added glutamate. Distinct protein bands were produced under stressful conditions, which indicate that these proteins might be stress proteins that aid the isolates to counteract osmotic stress. Keywords: Osmotic stress; L-Glutamate; Escherichia coliDOI: http://dx.doi.org/10.3329/bjm.v25i1.4865 Bangladesh J Microbiol, Volume 25, Number 1, June 2008, pp 79-81

The heart in anemia.

The following brief summary seems justified from the large volume of accumulated data dealing with the reaction of the cardiovascular system in the anemic patient. There are four mechanisms operating in the anemic patient which may increase the supply of oxygen to the tissues when the oxygen carrying capacity of the blood is reduced. Under conditions of rest, a rapid velocity flow and tachycardia with an increase in minute volume of cardiac output is the first response to anemia. As compensation develops, tachycardia and increased velocity flow are largely replaced by selective shunting of blood and the removal of an increasing percentage of oxygen in the tissue capillaries from each gram of circulating hemoglobin. These later physiologic mechanisms are best illustrated by patients with chronic parasitic anemias. Under conditions of physical stress each of the four physiologic mechanisms contribute in meeting the demands for increased oxygen requirements. Compensation is, however, never perfect; the status of the patient is determined by the reduction in hemoglobin, the tissue oxygen requirements, the presence of physical changes in the cardiovascular and pulmonary systems, degree of oxygen abstraction from the blood, and the selective shunting of blood. In relatively acute anemia, dyspnea readily occurs on physical exercise. Reduction in the ventilatory capacity of the lung occurring in some anemic patients results from an over-all reduction in physical fitness due to the anemic state rather than to physical changes in the lung. In well compensated, chronic anemia, the vital capacity of the lungs is frequently above normal and similar to that observed in athletes and completely acclimatized, high altitude inhabitants. In the absence of cardiovascular disease or physical or metabolic factors requiring increased cardiac output, true congestive heart failure rarely results from the anemic state. Effort angina is uncommon in anemic patients and when present is usually related to underlying coronary artery disease. Cardiac hypertrophy under certain conditions results from prolonged anemia. Since cardiac hypertrophy is rightly placed in the category of organic heart disease, one is justified in classifying chronic anemia as one of the etiologic factors in the production of heart disease.