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Query: UMLS:C0015672 (fatigue)
 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Stripped duodenal mucosa of rabbits was mounted in Ussing chambers containing a Ringer solution gassed with 100% O2. The disappearance of acid or alkali from the mucosal solution of short-circuited tissue was measured with a pH stat while the serosal pH was kept at 7.4. The duodenum rapidly disposed of both acid and alkali; neither property was altered by gassing with N2 while iodoacetate was in the perfusing solutions. Prevention of release of CO2 from the mucosal chamber obliterated the early rapid phase of acid disposal by the mucosa while a similar maneuver in the serosal chamber increased the appearance of serosal acid without altering the rate of acid disposal. Gut sacs of rabbit duodenum in vitro and in vivo showed a positive correlation between acid disposal and the rate of luminal CO2 production. While acid disposal progressively decreased with time for the in vitro gut sacs, the in vivo gut sac showed no fatigue in this respect. Luminal acidification in the Ussing chamber was associated with a profound reduction in short-circuit current (Isc), partially reversible by elevation of the mucosal pH but not by luminal glucose. Our data suggest that acid disposal occurs in part by intraluminal neutralization and in part by diffusion into the mucosa.
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PMID:Mechanisms of disposal of acid and alkali in rabbit duodenum. 0 19

1 We have studied the effects of single oral doses of 80 mg propranolol and 100 mg metoprolol on the cardiovascular and respiratory responses to progressive exercise in nine healthy men in double-blind, placebo-controlled experiment. As judged by their effects on exercise heart rate and cardiac output the doses of the two drugs used were equivalent. 2 Beta-adrenoceptor blockade reduced oxygen consumption by 3.5% over the whole work range with an increase in the respiratory exchange ratio of 0.056 units. Carbon dioxide production and exercise ventilation were unchanged. The two drugs had similar effects. Possible mechanisms for these observations are discussed. 3 Perceived exertion during exercise was increased by both the beta-adrenoceptor blocking drugs and this may be of relevance to the symptom of fatigue reported by patients on these drugs. Endurance, assessed as either total work done or maximal work achieved, was reduced by 15%.
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PMID:The effect of beta-adrenoceptor blockade on factors affecting exercise tolerance in normal man. 3 85

The metabolic effects of 60-min exposure to 250-2000 mg gamma-hydroxybutyrate (GHB) per kilogram or 150-1200 mg gamma-butyrolactone (GBL) per kilogram were studied in rats by measurement of the cerebral hemisphere contents of energy phosphates and glycolytic-Krebs' cycle metabolites. A general pattern of increased glycogen and glucose with decreased pyruvate, lactate, alpha-ketoglutarate, and malate was observed. This pattern in association with unchanged adenylates and decreased energy phosphate utilization was consistent with a metabolic adaptation to a state of cerebral depression. The major qualitative difference between the two drugs was that higher doses of GBL were associated with additional decreases of citrate and glutamate. Since these doses of GBL were also associated with acute increases of arterial CO2 tension, it is proposed that these differences were secondary to hypercapnia and not due to a distinctive primary action of GBL. Derivation of the cytoplasmic NAD(P)H:NAD(P)+ ratios indicated that GHB and GBL were not associated with consistent alterations of the cytoplasmic redox state.
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PMID:A comparison of the effects of gamma-hydroxybutyrate and gamma-butyrolactone on cerebral carbohydrate metabolism. 4 Jun 77

We have previously demonstrated that diaphragmatic muscle fatigue can be diagnosed in infants from spectral frequency analysis of the surface diaphragmatic electromyogram. This requires a digital computer, but the analysis takes several days. Spectral frequency changes, however, can be accurately reflected by band pass filtering and expressing the ratio of high-frequency power to low-frequency power. A fall in this ratio of greater than 20% indicates muscle fatigue. Using a simple analog device to obtain this ratio permits the results to be immediately available; we have used this method to study weaning from mechanical ventilators in ten infants. With a successful weaning step there is no significant change in the ratio, whereas an unsuccessful weaning step invariably leads to a decrease in the ratio of greater than 20%, which precedes CO2 retention and clinical deterioration. These data indicate that diaphragmatic muscle fatigue plays an important role in the infant's response to lung disease. Monitoring of the high/low frequency ratio may be helpful in weaning infants from assisted ventilation.
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PMID:The consequences of diaphragmatic muscle fatigue in the newborn infant. 38 13

Twenty-two smokers with elevated hematocrits (mean, 54 per cent) had elevated blood carboxyhemoglobin (mean, 11.6 per cent; normal, less than 1 per cent) and a "left-shifted" oxygen-hemoglobin dissociation curve (mean P50, 21.6 +/- 2.3 [+/- S.D.] torr; normal, 26.7 +/- 1.1). Red-cell volume was increased in 14 of 18, and plasma volume reduced in 14 of 18. Fatigue and headache were common, and syncopal attacks occurred in four patients. Symptoms disappeared and the elevated red-cell volume decreased markedly in all five patients who were able to reduce severely their smoking habit; low plasma volume increased in three of four patients studied. We conclude that carbon monoxide exposure from cigar and cigarette smoke is a frequent cause of an elevated red-cell volume or a reduced plasma volume (or both). Measurement of carboxyhemoglobin should be a routine part of the evaluation of all polycythemic subjects.
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PMID:Smokers' polycythemia. 61 65

Ten subjects were exposed to high-G on the human centrifuge using seatback angles of 13 degrees, 30 degrees, 45 degrees, 60 degrees, and 75 degrees from the vertical, and body configurations of the lower portion of the body with pelvis and legs elevated, pelvis, elevated, and pelvis elevated with knees on chest (fetal position). Tolerance was measured by peripheral light loss. Mental status, respirations, core and ambient temperatures, and ECG were monitored. Daily physio-chemical data included: creatinine, bilirubin, phosphorus, alkaline phosphatase, uric acid, cholesterol, total protein, albumin, BUN, glucose, LDH cardiac isoenzyme No. 5, SGOT, SGPT, CPK, CBC, and urinalysis. Tiredness, pressure on the chest, and general discomfort in the fetal position were reported. Physical examination demonstrated petechiae. Heart rate, respiratory rate, and temperature increased post-session. There was a significant rise in values for albumin, chloride ion, creatinine, calcium, LDH, BUN, and immature white cells; and a decrease in values for phosphorus, SGOT, SGPT, protein, uric acid CO2, globulin, hematocrit, monocytes, and eosinophils.
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PMID:Psycho-physiological assessment of acceleration-induced changes in various seat configurations. 86 40

Multiple serum chemical values were examined in 92 patients with chronic glaucoma who were treated with the carbonic anhydrase inhibitors (CAIs) acetazolamide or methazolamide, seeking relationships between serum composition and symptomatic side effects. Of the 92 patients, 44 complained of a symptom-complex of malaise, fatigue, weight loss, depression, anorexia, and loss of libido, which we have found most commonly to threaten continuation of therapy. Patients who had this symptom complex were significantly more acidotic than those without it. Ten of 24 patients who had chemical evidence of excessive acidosis reported a dramatic alleviation of symptoms when sodium bicarbonate was administered, although their serum CO2-combining power changed little. There was no correlation of the symptom complex with serum potassium concentration, except in a few patients who were simultaneously receiving chlorothiazide diuretics for systemic hypertension and who became frankly hypokalemic.
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PMID:Carbonic anhydrase inhibitor side effects. Serum chemical analysis. 88 13

A syndrome of alveolar hypoventilation has been identified in a group of patients with bilateral diaphragm paralysis. Eight patients were studied in whom diaphragm weakness had been suggested by paradoxical (inward) movement of the abdominal wall on inspiration, of whom seven had evidence of a generalized neuromuscular disorder. Diaphragm function was assessed quantitatively by measurement of the change in transdiaphragmatic pressure during a maximum inspiration (deltaPDi). In five patients, deltaPDi was zero and in the others ranged from 2-6 cm H2O (normal greater than 25 cm H2O) indicating paralysis and severe weakness in the respective groups. Fluoroscopy of the diaphragm was found to give misleading results, and the resons for this are considered. Vital capacity ranged from 65-30 per cent of the predicted normal in the upright posture, typically falling by about a half in the supine posture. Alveolar hypoventilation was present in five patients when supine and in six when asleep, the deterioration in blood gases associated with sleep generally being much greater in these patients than in normal subjects. Respiratory rate was significantly greater than age-matched controls. The ventilatory response to CO2 was impaired. The PCO2 could be brought to normal levels by voluntary hyperventilation, and the unreliability of voluntary respiratory manoeuvres of this kind as indices of ventilatory reserve is emphasized. Alveolar hypoventilation was associated with disturbed sleep, morning headache and day-time fatigue. Symptomatic benefit was achieved by the use of a cuirass respirator at night.
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PMID:Diaphragm function and alveolar hypoventilation. 106 15

Yawning in reptiles was investigated in field observations of various lizard and tortoise species and in laboratory experiments with the tortoises Testudo h. hermanni and Emys orbicularis. In the experiments the animals' reactions to various conditions of temperature, air O2 and CO2 content, fatigue and hunger, were tested. Yawning and related or similar motor patterns are described and discussed.
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PMID:[The problem of yawning in reptiles]. 114 23

The aim of the study was to ascertain the reasons which lead to discontinuance of exercise on the bicycle ergometer in healthy untrained subjects and to assess the dependence of dyspnea on breathing pattern and on ventilation. The physical load was progressively increased to the maximum in 11 volunteers at the age of 21 +/- 1 years. During exercise some cardiovascular and respiratory parameters were measured simultaneously with the degree of dyspnea. Breathlessness was rated by means of a scaling according Borg, where 0 indicates no, 10 maximal dyspnea. Dyspnea was not a reason for termination of maximal exercise, its value being 6 +/- 1.9 in men and 4.5 +/- 2.3 in women at the end of exercise. The reasons for termination of exercise were the sensations of general fatigue and pain in lower the extremities. The degree of dyspnea correlated with the minute ventilation, with the decrease of end-tidal CO2 concentration, with the duration of exercise and some other values. The grading varied among subjects. The mathematical dependence of dyspnea was summarised by two regression equations, one without suppression, the other with suppression of interindividual differences in responses.
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PMID:Breathlessness in healthy subjects at physical load. 130 83


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