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

Intermittent hyperthyreosis occurs under various forms of stress, especially heat stress. The clinician may diagnose such cases as masked or apathetic hyperthyroidism or "forme fruste" hyperthyreosis or thyroid autonomy. As most routine and standard tests may here yield inconsistent results, it is the patients' anamnesis which may provide the clue. Our Bioclimatology Unit has now seen over 100 cases in which thyroid hypersensitivity towards heat was the most prominent syndrome: 10-15% of weather-sensitive patients are affected. The patients complain before or during heat spells of such contradictory symptoms as insomnia, irritability, tension, tachycardia, palpitations, precordial pain, dyspnoe, flushes with sweating or chills, tremor, abdominal pain or diarrhea, polyuria or pollakisuria, weight loss in spite of ravenous appetite, fatigue, exhaustion, depression, adynamia, lack of concentration and confusion. Determination of urinary neurohormones allows a differential diagnosis, intermittent hyperthyreosis being characterized by three cardinal symptoms: 1. tachycardia -- every case with more than 80 pulse beats being suspect (not specific); 2. urinary histamine -- every case excreting more than 90 mug/day being suspect. Again the drawback of this test is its lack of specificity, as histamine may also be increased in cases of allergy and spondylitis; 3. urinary thyroxine -- every case excreting more than 20 mug/day T-4 being suspect. This is the only specific test. Therapy should make use of lithium carbonate and beta-blockers. Propyl thiouracil is rarely required.
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PMID:Intermittent hyperthyreosis -- a heat stress syndrome. 5 84

The effect of dipeptides (carnosine and anserine) on a neuromuscular preparation under fatigue or diplacine blocking is shown to result in a significant restoration of the muscle contraction. The analysis of this phenomenon evidences that synaptic processes are not responsible for the restoration, at least under the given experimental conditions. At the same time, the absence of any effect of the compounds studied on the maximal rate of isotonic shortening and on the tension of glycerinized fibres and ATPPase of native and desenitized actomyosine indicates that the contractile mechanism is not involved in the effect described. On the other hand, the dipeptides restore the value of the transmembrane potential depolarized by exhaustion, increase the amplitude of isometric twitch and the value of maximal load under isotonic conditions. Moreover, the time of the contractile cycle in the presence of the dipeptides is considcted to the processes of electromechanical coupling in skeletal muscles.
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PMID:[Effect of carnosine and anserine on excitation and contraction of fatigued skeletal muscle]. 13 81

A questionnaire study on work conditions, work organization, leisure time, social problems, and health was directed toward active and retired locomotive engineers. This article mainly presents responses of the active engineers. The active locomotive engineers quoted the irregular work hours as the worst occupational problem. They judged noise and vibration in the locomotive cabs as disturbing. The majority of the desired changes in the work and work conditions concerned work time. The most common complaints given on the questionnaire were back trouble, hypertension and dermatitis. Tiredness and exhaustion were the most prevalent neuropsychological symptoms. A retrospective follow-up survey on invalidity and mortality was made. Trainmen and railroad clerks were used as reference cohorts.The engineers had relatively high invalidity and mortality rates in comparison to the reference groups, especially with respect to cardiovascular diseases and malignant tumors. Higher rates for disease of the digestive system and hearing loss were also suggested by the results.
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PMID:Work conditions and health of locomotive engineers. II. Questionnaire study, mortality and disability. 15 82

The result of biochemical and mathematical analysis of restitution processes after various exercises determined the phases of these processes and the interrelationship between metabolic structure of restitution and the character of exercise. Metabolic structure of restitution has some common traits in recovery period after non-fatiguing exercises and exercises causing a rapidly developing fatigue. In contrast, sharp changes of this structure occur after exercises causing a slowly developing exhaustion.
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PMID:[Metabolic structure of the restitution process following physical loads of a different character]. 21 Oct 53

In 4 patients with clinical signs of dermatomyositis, confirmed by electromyography and muscle biopsy, a form of muscle fatigue was detected which was expressed clinically by predominantly proximal motor deficit, with phonation and deglutition disturbances, slightly influenced by prostigmine. In all patients, stimulation of the ulnar nerve at 3--10 Hz induced a decrement of muscle-evoked potentials in abductor digiti minimi and at 15--50 Hz an increment at the end of the trains (1.2 sec in duration) of repetitive stimulation (preceded in two cases by a decrement in the response to the fifth stimulus in the train). Stimulation at 30 Hz for 10 sec resulted in a transient facilitation, followed (at 3 Hz stimulation) by postactivation exhaustion which disappeared after 5--15 min. The post-tetanic facilitation, the incremental response and the myasthenic symptoms reverted to normal under treatment with corticosteroids, an immunosuppressor agent and guanidine hydrochloride. A mixed, pre- and postsynaptic mechanism is presumed to underlie the muscle fatigue in our patients. Electron microscopy of muscle biopsies disclosed zones of necrosis and, in incipient stages, large agglomerations of glycogen that had disorganized the structure of myofibrils. The end-plates in the biopsies were larger than normal and the cholinesterase reaction was hyperactive. Serum immunoelectrophoretic and electrophoretic data--increase of IgG and IgM, decrease of IgA and hypergammaglobulinaemia -- point to a possible autoimmune mechanism of the neuromuscular disorders in our patients.
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PMID:Myasthenia in patients with dermatomyositis: clinical, electrophysiological and ultrastructural studies. 21 37

The author reports changes in vibration and two-point discrimation sensitivity in groups of healthy young males after several days of intense physical effort and after one short-lasting intense exercise. The vibration sensitivity was a steady type of sensory function showing no significant changes after these workloads. The two-point discrimination sensitivity was, not infrequently, better after several days of effort in relation to preliminary state, and it was regarded as an evidence of adaptation to work. On the other hand, one sort-lasting exercise reduced significantly discrimination of two stimuli, especially on the lower extremities. This significant impairment of two-stimuli discrimination on the lower extremities in relation to the upper ones after intensive effort suggests easier exhaustion of pathways conveying sensation in the thoracic segment of the spinal cord. On the basis of these investigations the author thinks that aesthesiometric investigations carried out under strictly observed conditions may be useful for assessment of fatigue.
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PMID:[Effect of various forms of physical exertion on selected types of sensory function]. 48 91

The purpose of this study was to determine the influence of diurnal variations of muscle and liver glycogen stores on exercise endurance in male albino rats. Animals were swum to exhaustion at either 0700 or 1900 h, after which samples of soleus, white vastus lateralis, and red vastus lateralis muscles as well as liver were excised and subsequently analyzed for glycogen content. Glycogen content of all tissues from nonexercising control animals was higher in the morning than in the evening. Consequently, animals at 0700 h swam 60% longer than those at 1900 h (209 +/- 20 min vs. 130 +/- 23 min, respectively). However, because the skeletal tissues of the exhausted animals were not totally depleted of glycogen, it was concluded that fatigue under the swim protocol was the result of hypoglycemia secondary to hepatic glycogen depletion. The results of this study demonstrate the physiological consequences of diurnal glycogen fluctuation and establish experimental support for the importance of controlling this variable in rodent exercise investigations.
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PMID:Muscle and liver glycogen content: diurnal variation and endurance. 57 22

The pharmacological activity of hematoporphyrin has been studied on two experimental models which are able to monitor the motor coordination in the rat, namely the natatory exhaustion and the Rota-Rod tests. A dose related effect of hematoporphyrin in increasing resistane to motor fatigue has been observed in the Rota-Rod between 2-8 mg/kg i.p. Higher doses of hematoporphyrin seem to be less effective (difasic effect). In both tests hematoporphyrin was able to potentiate the stimulating effect of d-amphetamine (6 mg/kg s.c.). The potentiation appeared to be dose related between 2 and 8 mg/kg in the Rota Rod and between 2 and 16 mg/kg in the natatory test.
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PMID:[Stimulating action of hematoporphyrin on motor coordination and resistance to fatigue in rats]. 61 Jun 90

The experiments were carried out in rabbits and rats during 1--7.5 months. They demonstrated increasing disturbances in ultrastructure of the protein synthesizing myocardiocyte apparatus. The major and most dangerous disorder is the deficiency in the myocardial apparatus, which is, evidently, the main cause in the reduction of the cardiac functional reserves. Externally, similar reaction of the organism in response to loading (treadmill)--deep fatigue--produces diverse ultrastructural changes in the myocardium depending on the initial adaptive level to motor activity. In rabbits, having satisfactory adaptation to motor activity, the loading (treadmill) results, mainly, in exhaustion of their energy storage. In disadapted animals it produces dangerous lesions in the contractile apparatus of the cardial myocytes.
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PMID:[Effect of hypokinesia and physical loading on the ultrastructure of cardiac myocytes]. 62 95

It has been shown previously (this journal) that any activity, physical or mental, performed as "diverting activity" in the pauses between bouts of exhaustive musclar work has a positive effect on the recuperation after fatigue. It was concluded that this effect was primarily of central nervous origin (Setchenov, 1903) and not a circulatory effect (Weber, 1914). In the present experiments it is shown that the amount of work that can be performed before exhaustion is larger when the subjects work with their eyes open than when they work with closed eyes. Further, when complete exhaustion has been reached with closed eyes, opening of the eyes results in an immediate return of a working capacity amounting to 15-30% of that already performed. It is demonstrated, that patellar reflexes are brisker when the eyes are open than when they are closed. The same is the case during the diverse forms of "diverting activity" used in this and the previous article. The brisker myotatic reflexes are taken to mean an enhanced central nervous arousal, and the recuperative effect of "diverting activity" is consequently explained as being due to an increased facilitation of the neuro-motor system, which in fatigue is inhibited centrally through afferents from receptors in the fatigued muscles.
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PMID:A central nervous component in local muscular fatigue. 63 Nov 22


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