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

Circadian rhythms in urinary catecholamine excretion, performance and self-ratings were studied in two experiments with a total of 29 subjects who were deprived of sleep for 72 hr. Adrenaline excretion and fatigue ratings showed the most consistent circadian variations; noradrenaline and performance rhythms were more irregular. The average crest phase for adrenaline excretion was around 1400 hr, for noradrenaline about 0800 hr, for performance 1700 hr and for fatigue 0500 hr. Twenty-four hour levels of performance and 'subjective arousal' decreased over the three days of sleep deprivation, while adrenaline excretion levels increased.
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PMID:Circadian rhythms of catecholamine excretion, shooting range performance and self-ratings of fatigue during sleep deprivation. 113 17

To evaluate physical and mental workload in middle-aged workers, urinary excretion of catecholamines and cortisol and self-reported scores of fatigue, stress and arousal in middle-aged steel workers were compared with those in young steel workers. Noradrenaline excretion in daytime of the day-off was higher in middle-aged workers than that in young workers. In the work days, noradrenaline excretion during working hours increased in both age groups when compared with that in the day-off. The work-related increase in noradrenaline excretion was more evident in the middle-aged group than in the young group. Adrenaline excretion during working hours was greater in the middle-aged group than that in the young group, whereas the adrenaline value in the day-off was almost the same in the two age-groups. Age-difference was hardly observed in dopamine and cortisol excretion. These findings suggest that the workload in middle-aged workers was greater than that in young workers. However, self-reported scores of fatigue and stress in middle-aged workers were less than those in young workers, suggesting inconsistency between subjective score of workload and urinary levels of catecholamines. These age-related differences in urinary levels of noradrenaline and adrenaline were not so obvious in workers engaged in automated and mechanized work (vigilance task) when compared to workers engaged in less automated and less mechanized work. It is considered that factory automation might reduce the workload in middle-aged workers.
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PMID:[Evaluation of workload in middle-aged steel workers by measuring urinary excretion of catecholamines and cortisol]. 177 Jun 15

The role of extracellular K+ concentration in the propagation velocity of action potential was tested in isolated rat skeletal muscles. Different K+ concentrations were produced by KCl additions to extracellular solution. Action potentials were measured extracellularly by means of two annular platinum electrodes. Fibre bundles of m. soleus (SOL), m. extensor digitorum longus (EDL), red (SMR) and white (SMW) part of m. sternomastoideus were maximum stimulated. The conduction velocity (c.v.) was calculated from the distance between the electrodes and the time delay of the potentials measured at 22 degrees C. In Tyrode solution containing 5 mmol/l K+, the c.v. was close to 1 m.s-1. Bundles of the fast muscle type seemed to have a somewhat higher c.v. The differences observed in these studies were not significant. At higher temperatures, the c.v. increased (Q10 of approx. 2) and a dissociation between SMR and SMW muscles appeared. An elevation of K+ concentration to 10 mmol/l induced a drop of the c.v. by approx. 25% and 15% in EDL and SOL muscles, respectively. After return to normal solution, the recovery was not complete within 30 min. In K+ free solution the c.v. of EDL and SM muscles rose by a factor of 1.5, but less in SOL muscles. The weaker response of SOL to K+ modification was related to the higher resistance of this muscle to fatigue. This suggestion was supported by experiments on fatigued fibre bundles. Immediately after a tetanic stimulation producing fatigue, the c.v. of EDL and SOL muscles dropped similarly as in 10 mmol/l K+; again, the drop was less for SOL muscles. Adrenaline (0.5-10.0 mumol/l) enhanced both the c.v. and the twitch amplitude. The results support the suggestion that extracellular K+ accumulation during activity is an essential factor of muscle fatigue.
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PMID:External potassium and action potential propagation in rat fast and slow twitch muscles. 181 28

The roles of cAMP and inorganic phosphate (Pi) in the regulation of muscle glycogenolysis during exercise have been investigated in humans using the needle biopsy technique. The fraction of phosphorylase a in resting muscle was as a mean 23%, but the rate of glycogenolysis was extremely low. Epinephrine infusion increased cAMP in muscle by 3-fold and transformed 80% of phosphorylase to the a form. Despite this, the rate of glycogenolysis was only 5-10% of the maximum rate of phosphorylase a (Vmax a) determined in vitro. Isometric exercise for 25 s at 66% MVC or electrical stimulation for 50 s at 20 Hz transformed about 53% and 80% of phosphorylase in the a form. The rate of glycogenolysis ranged between 50-90 mmol.kg-1.dm.min-1 and was close to Vmax of phosphorylase a determined in vitro. No significant difference in the rate of glycogenolysis in muscle was observed after isometric exercise to fatigue without and with epinephrine infusion, respectively. Apparently the rate of glycogenolysis in muscle is not solely related to the fraction of phosphorylase in the a form. Several factors could be responsible for allosteric and/or substrate regulation. The results in the present studies can be explained on the basis of substrate regulation of phosphorylase activity, provided that Pi is present in a limiting amount at the active site of phosphorylase in muscle at rest. It is concluded that transformation of phosphorylase b to a is important but alone is not adequate for a high activity and thus for a high rate of glycogenolysis in muscle.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Role of cyclic AMP and inorganic phosphate in the regulation of muscle glycogenolysis during exercise. 285 69

Water deprivation (WD) resulted in increased serum osmotic pressure (OP) and decreased body weight (WB); adrenal aldosterone content did not change. Adrenal corticosterone content tended to be elevated during early WD, indicating a stress response, but tended to decrease after seven days of WD, suggesting adrenal fatigue. During water restriction (WR), after the period of weight loss, adrenal corticosterone content and serum OP were elevated. As the birds began to gain weight, aldosterone levels did not change but adrenal corticosterone content and serum OP approached control values, suggesting that the birds were beginning to adapt to the WR. Adrenal sensitivity to ACTH was indicated by the elevated adrenal aldosterone and corticosterone content after ACTH injection.
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PMID:Adrenal responses to chronic and acute water stress in Japanese quail Coturnix japonica. 285 51

To investigate adrenergic receptor-mediated responses in dog gastrocnemius-plantaris muscle, several catecholamine agonists, isoproterenol, epinephrine, norepinephrine, and phenylephrine, and two antagonists, propranolol and phenoxybenzamine, were given during repetitive, isotonic, tetanic contractions. The response variables that were measured were muscle blood flow, shortening during constant load contractions, and arterial and venous O2 and lactate concentrations. The calculated variables were O2 uptake (VO2), net lactic acid output (L), and power output. In the control experiments, the contractions increased VO2 to approximately 50 times rest by 2 min. Thereafter, shortening, work, and VO2 declined together by 17% at 30 min, indicating muscle fatigue. L increased rapidly to nearly 0.8 mumol X g-1 X min-1 by 2 min, declined to 0.3-0.4 mumol X g-1 X min-1 by 7 min, and was like rest at 15, 22.5, and 30 min. The arterial lactate concentration rose steadily from rest to 30 min of contractions. Epinephrine infusion stopped the decline of VO2 during the contractions, but this effect was not observed with the other agonists. Propranolol decreased VO2 compared with controls at 22.5 and 30 min of contractions. Phenoxybenzamine decreased VO2 compared with controls at all times during contraction, and the decline with time was present. Coinfusion of epinephrine with propranolol reduced the decline in VO2 observed with propranolol alone. Both epinephrine and isoproterenol increased L compared with controls. This epinephrine response was antagonized by propranolol but enhanced by phenoxybenzamine. Both isoproterenol and epinephrine infusions increased arterial lactate concentration.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of adrenergic agonists and antagonists on muscle O2 uptake and lactate metabolism. 288 2

The importance of subcellular storage, nerve impulse rate and pattern, and feedback regulation, as well as resupply by axonal transport for the release of noradrenaline and neuropeptide Y-like immunoreactivity, was studied in the blood perfused pig spleen in vivo. Vasoconstrictor responses were recorded as perfusion pressure changes. Subcellular fractionation experiments using sucrose density gradients showed a bimodal distribution of noradrenaline (peak concentrations at 0.8 and 1.1 M sucrose) while only one main peak of neuropeptide Y was present (at 1.1 M sucrose). Overflow suggesting release of noradrenaline and neuropeptide Y-like immunoreactivity could be detected after 10 s stimulation at 10 Hz. The ratio for the output of noradrenaline and neuropeptide Y upon continuous nerve stimulation in control animals decreased with frequency. After inhibition of noradrenaline reuptake by desipramine the vasoconstrictor response and noradrenaline output were enhanced while the corresponding overflow of neuropeptide Y was reduced by 50% at 0.5 Hz. Stimulation with the irregular or regular bursting patterns at high frequencies caused larger perfusion pressure increase and relative enhancement of neuropeptide Y output compared to noradrenaline than a continuous stimulation both before and after desipramine treatment. A similar fractional release per nerve impulse was calculated both for [3H]noradrenaline (5.6 +/- 1.0 x 10(-5) and neuropeptide Y (7.3 +/- 0.3 x 10(-5). After reserpine treatment combined with preganglionic denervation the vasoconstrictor responses were more long-lasting, neuropeptide Y release was enhanced while noradrenaline content and release were reduced by 99%. The difference in neuropeptide Y overflow between continuous and bursting types of stimulation was smaller after reserpine treatment. After prolonged intermittent stimulation with regular bursts (20 Hz) for 1 h the splenic content of neuropeptide Y was reduced by 58%, while no change was observed for noradrenaline. The maximal perfusion pressure increase upon prolonged nerve stimulation after reserpine was similar in control and reserpine-treated animals, but after reserpine the vasoconstrictor response and neuropeptide Y release were subjected to fatigue. Ligation experiments of the splenic nerves revealed the splenic neuropeptide Y content was resupplied by axonal transport with a calculated total tissue turnover time of 11 days. In contrast, axonal transport contributed only to a marginal extent for the resupply of noradrenaline.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Co-release of neuropeptide Y and noradrenaline from pig spleen in vivo: importance of subcellular storage, nerve impulse frequency and pattern, feedback regulation and resupply by axonal transport. 292 11

Ten patients with adrenal cortical carcinoma were treated from 1966 to 1986. There were 7 males and 3 females. The typical clinical manifestations, marked increase of 17-ketosteroid, 17-hydroxycorticoids and DHA, and negative dexamethasone suppression test were essential for the diagnosis. Of the ten patients, eight had secretive function and their 17-ketosteroid and 17-hydroxycorticoids varied from 36.8-93 mg% and 32.5-150 mg%, respectively. DHA was measured in 5 cases with the result of 6.95-44mg%. Those without secretive functions or obvious endocrine disturbances were usually misdiagnosed as kidney tumor, splenomagaly, liver tumor or pancreatic mass. Wood had summarized that nonsecretive ACC patients commonly had fever, pain, exhaustion syndrome (emaciation, fatigue, perspiration, anorexia), mass and distant metastasis. Adrenal scan, IVU, abdominal aortic arteriography, retroperitoneal pneumography and CT were helpful in localization. The differential diagnosis between ACC and adenoma by pathology was difficult. It is generally agreed that if the mass is larger than 100 grams, capsulated, having blood or lymphatic vessel invasion, hemorrhage, necrosis and calcification or even distant metastasis, malignant tumor should be considered. Surgical removal of the tumor is the only effective treatment. For advanced or recurrent lesions, selective adrenal artery thrombosis could be used. One of the ten patients was thus treated by this facilitated subsequent surgery. Postoperative chemotherapy, such as O.P-DDD, might be used in some cases.
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PMID:[Adrenal cortical carcinoma (ACC)--report of 10 cases]. 297 73

A 9-year-old boy who complained of fatigue, myalgias, and progressive weakness was found to have a markedly elevated serum creatine phosphokinase (CPK). He developed polyuria with polydipsia and was noted to be hypertensive and severely hypokalemic. Treatment with potassium and spironolactone alleviated his signs and symptoms and normalized the blood pressure and CPK. Initial studies revealed low plasma renin activity that did not increase with change from supine to upright position. Plasma aldosterone was consistently elevated in the supine position, decreased with upright posture, and was not suppressed by administration of dexamethasone. Plasma 18-hydroxycorticosterone also was elevated. Enhanced computerized tomography (CT) revealed a mass in the left adrenal that had not been seen on the initial unenhanced scan. Adrenal vein catheterization confirmed elevated plasma aldosterone on that side. Adrenalectomy was performed, and a well-encapsulated adenoma was found at examination of the surgical specimen. Postoperatively, suppression of plasma renin activity continued for many months without signs of aldosterone deficiency.
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PMID:Aldosterone-producing adenoma presenting with hypokalemic myopathy. Case report and review. 329 4

Unilateral adrenal tuberculosis is a very rare disease. A 66-year-old woman presented with epigastric discomfort and general fatigue. Abdominal CT scan revealed a homogeneous mass shadow in the right adrenal region. Findings of physical examination were normal except that the patient was obese. Hormonal data were in normal range. Adrenal scintiscanning demonstrated no RI uptake in the right adrenal gland. Right adrenalectomy was performed under the diagnosis of nonfunctioning tumor of the right adrenal gland. Histopathological examination, however, revealed typical tuberculosis with Langhans' type of giant cells and infiltrated lymphocytes. Of 322, 148 autopsies performed during the twelve years between 1970 and 1981 in Japan, 228 cases of adrenal tuberculosis were recognized. Furthermore, only 18 cases had tuberculous regions in the adrenal gland alone.
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PMID:[Tuberculosis of the contralateral adrenal gland: a case report]. 402 81


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