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

Electron probe analysis, cryo-ultramicrotomy, and freeze-substitution were used to determine the nature of vacuolation and the subcellular composition in fatigued frog skeletal muscle fibers. The vacuoles caused by fatigue were part of the T-tubule system and contained high concentrations of NaCl. The calcium concentration in the terminal cisternae was higher than previously measured normal resting values. Mitochondrial calcium content was relatively low (mean +/- SEM, 2 +/- 2 mmol/kg dry weight). Fiber NaCl was increased. It is concluded that fatigue is not due to the depletion of calcium stores from the terminal cisternae or to uncoupling of mitochondria due to calcium loading but may be caused by multiple mechanisms including failure of the T-tubule action potential.
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PMID:Composition of vacuoles and sarcoplasmic reticulum in fatigued muscle: electron probe analysis. 2 54

There is much individual variability in the clinical manifestations of hypocalcemia. The rapidly of the development of hypocalcemia will determine whether or not symptoms will be present. Signs and symptoms of hypocalcemia consisted of tetany (Chvostek's and Trousseau's signs), seizures, diminshed to absent deep tendon reflexes, papilledema, mental changes (weakness, fatigue, irritability, memory loss, confusion, delusion, hallucination), and skin changes. Etiologic factors for hypocalcemia in man include (1) decreased calcium absorption or increased loss from the gastrointestinal tract; (2) parathyroid hormone deficiency; (3) skeletal resistance to parathyroid hormone; (4) ineffective parathyroid hormone; (5) decreased production or increased degradation of 25-hydroxycholecalciferol or 1,25-dihydroxycholecalciferol; (6) increased complex formation with calcium; (7) increased skeletal uptake of calcium; (8) hypomagnesemic state; and (9) direct inhibition of bone resorption. Measurement of total and ionic calcium, magnesium, parathyroid hormone, vitamin D metabolites (25-hydroxycholecalciferol, 1,25-dihydroxycholecalciferol), and nephrogenous cyclic adenosine monophosphate are especially helpful in the laboratory evaluation of the hypocalcemic patient.
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PMID:Hypocalcemia. Differential diagnosis and mechanisms. 22 22

Fatigue and recovery from fatigue were related to metabolism in single fibers of the frog semitendinosus muscle. The fibers were held at a sarcomere length of 2.3 microm in oxygenated Ringer solution at 15 degrees C and were stimulated for up to 150 s by a schedule of 10-s, 20-Hz tetanic trains that were interrupted by 1-s rest periods, after which they were rapidly frozen for biochemical analysis. Two kinds of fatigue were produced in relation to stimulus duration. A rapidly reversed fatigue occurred with stimulation for under 40 s and was evidenced by a decline in tetanic tension that could be overcome by 1 s of rest. A prolonged fatigue was caused by stimulation for 100-150 s. It was evidenced during stimulation by a fall in tetanic tension that could not be overcome by 1 s of rest, and after stimulation by a reduction, lasting for up to 82 min, in the peak tension of a 200-ms test tetanus. Fiber phosphocreatine (PCr) fell logarithmically in relation to stimulus duration, from a mean of 121 +/- 8 nmol/mg protein (SEM, n = 12) to 10% of this value after 150 s of stimulation. PCr returned to normal levels after 90-120 min of rest. Stimulation for 150 s did not significantly affect fiber glycogen and reduced fiber ATP by at most 15%. It is suggested that the prolonged fatigue caused by 100-150 s of tetanic stimulation was caused by long-lasting failure of excitation-contraction coupling, as it was not accompanied by depletion of energy stores in the form of ATP. One possibility is that H+ accumulated in fatigued fibers so as to interfere with the action of Ca2+ in the coupling process.
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PMID:Metabolic correlates of fatigue and of recovery from fatigue in single frog muscle fibers. 31 Aug 67

A study is presented of 14 patients with hyperparathyroid crisis treated at the Massachusetts General Hospital between 1964 and 1978. These patients showed diverse clinical manifestations that were indistinguishable from those in patients with pseudohyperparathyroidism. Their symptoms varied from progressive fatigue, malaise, and weakness to those related to the gastrointestinal and urinary tracts. The one biochemical alteration commonly found among these patients was the rapid increase in the serum calcium. There was a concomitant rise in the BUN in 50% of the patients and in the creatinine in 80%. The diagnosis was established by an elevated immunoreactive parathyroid hormone (PTH) level in all eight patients (100%) who had the radioimmunoassay; by the presence of subperiosteal resorption of the phalanges in six of the eight patients (75%); and in three of four patients (75%) by the loss of the lamina dura of the teeth. The 12 patients who had surgery all survived; the two who did not died. Thirteen patients (93%) had a neoplasm--an adenoma in 12 and a carcinoma in one. One patient had hyperplasia (7%). Nine patients (64%) received hypocalcemic drug therapy. The serum calcium temporarily fell to 12 mg/100 ml in five patients (56%) but failed to budge in four (44%). Simultaneous treatment with saline infusion, furosemide and with hypocalcemic drugs over a prolonged period compounded the difficulty at operation by increasing interstitial edema. Our findings from this study show prompt surgical intervention as the ideal treatment for hyperparathyroid crisis, preferably, within 72 hours of the acute onset of symptoms.
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PMID:Hyperparathyroid crisis: clinical and pathologic studies of 14 patients. 51 79

Recent electron probe analytic studies of freeze-dried cryosections of vascular smooth and vertebrate striated muscle are reviewed. The results show that the sarcoplasmic reticulum of striated muscle is not in ionic communication with the extracellular space. Vacuolation by hypertonic solutions and fatigue involves the T-tubule system. The high calcium content of the terminal cisternae of the resting muscle has been quantitated in situ. In smooth muscle, the high Cl content is distributed in the cytoplasm, and mitochondria in rabbit portal vein smooth muscle cells do not contain high concentrations of calcium. Mitochondrial calcium loading in the form of granules is generally due to fiber damage. Nuclear and mitochondrial composition in situ has been quantitated and compared to the composition of the cytoplasm of the same cells. Preliminary phosphorus x-ray maps of smooth muscle show the feasibility of this approach in defining the composition of organelles in thin cryosections. The use of x-ray maps at intermediate resolution is illustrated with tropomyosin paracrystals labelled with Hg-containing dye at the thiol residues. Mercury x-ray maps of such paracrystals show the 40nm periodicity of the thiol groups and their Fourier transforms contain information to a spatial resolution of 10-20nm.
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PMID:Electron probe analysis of muscle and X-ray mapping of biological specimens with a field emission gun. 52 37

1. Latency relaxation and twitch tension were recorded simultaneously in single isolated muscle fibres of Xenopus laevis. 2. During low frequency (0.6 or 1 pulse/sec) repetitive stimulation, three successive phases of twitch tension were observed: negative staricase (a slight drop in tension), positive staircase (about 15% increase in tension) and fatigue. At the same time the amplitude of latency relaxation decreased monotonically, and near the peak of positive staircase, the amplitude decreased almost to an undetectable level. 3. The application of caffeine (0.1--1.5 mM) increased peak twitch tension by 15--200%, but decreased the latency relaxation amplitude by 30--93%. 4. The application of Ca-release inhibitors, deuterium oxide and dantrolene sodium, caused a 43--89% decline in peak twitch tension but no change in latency relaxation amplitude. 5. The lack of correlation between changes in peak twitch tension and latency relaxation amplitude suggests that latency relaxation is associated with the mechanism which triggers Ca2+ relase rather than with Ca2+ release itself.
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PMID:Latency-relaxation in single muscle fibres. 72 20

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

Preliminary results of this retrospective-prospective analysis of renal hypertension in 110 children indicate that hypertension may be secondary to a wide variety of acute progresive, and chronic renal diseases which may be either congenital or acquired. Affected children may be detected at any time from infancy through adolescence. Symptoms usually associated with acute glomerulonephritis (i.e., headache, swelling, nausea, vomiting, anorexia, fatigue, dizziness, and fever) occur in both acute and chronic renal diseases associated with hypertension. Headache and swelling are the most common symptoms in this series. Peripheral edema, rales, and increased heart size were found in between 10 and 25% of these children. Differential diagnosis may be approached by a consideration of causes of acute and chronic hypertension. The child with chronic renal disease usually presents with a long history of fatigability, poor growth, and pallor, and laboratory tests reveal elevation of the creatinine and BUN along with anemia, hypocalcemia, and hyperphosphatemia. In contrast, the child with acute renal disease and hypertension presents with a history of prior good health followed by the abrupt onset of signs and symptoms of renal disease; laboratory tests usually reveal modest elevations of creatinine and BUN, anemia is unusual, an abnormal urinalysis is common, and serum calcium and phosphorous levels are usually normal. Renovascular and asymmetric renal parenchymal disease represent uncommon but important conditions because surgery may be curative. Treatment may be surgical, medical, or combined. Surgical conditions include renal trauma, hydronephrosis, asymmetric renal disease, and renal arterial disease. Adequate blood pressure control without medication can be expected following surgery in instances of unilateral involvement with a normal contralateral kidney. Meticulous assessment of the contralateral kidney is needed to determine that it is normal. If surgery is unsuccessful or is not indicated, pharmacologic therapy is initiated with a stepwise regimen starting with the mildest agent (e.g., thiazides) and then adding additional antihypertensive drugs when adequate blood pressure control has not yet been achieved. The goal of therapy is the lowest, safest, tolerated blood pressure levels. Long-term, carefully designed studies of antihypertensive agents for children with renal hypertension are not available. The need for collection and critical analysis of data concerning the clinical course of children with renal hypertension is evident from a review of the literature and from the preliminary data presented in this series. The presentation of such information and a critique of outcome variables will provide a basis for program planning for affected children and improvement in patient care where indicated.
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PMID:Renal hypertension in children. 99 44

In a group of nine healthy but obese women a set of tests were used to estimate several physiological and psycho-physiological variables: self-rating of hunger, mood and physical vigor, self-recording of grip-strength, muscular fatigue test, eye-hand skill, tempo, etc. Measurements were performed every 6-hours, at fixed times, during 24-hours, once a week, before (non-restricted spontaneous food intake) and for three weeks on a 220 cal. special protein diet (calcium caseinate: 55g, associated with potassium salts, water and vitamins). Findings relating to the metabolic and hormonal variables while on this diet have already been reported: (a) The diet does not alter the circadian acrophase (peak) of the variables and (b) two distinct metabolic steps occur: first a peak of gluconeogenesis and second, a phase when ketone bodies and fatty acids are used almost exclusively as source of fuel. The present findings show that so long as nitrogen remains in balance this restricted diet (a) does not change the grip strength and the muscular fatigue test; (b) does not alter the mood, the physical vigor etc. and (c) induces a statistically significant fall in "hunger" (self-rating method). We conclude that this low protein diet is compatible with non-strenuous work.
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PMID:A chronobiological investigation of fitness for work in women on a 220 cal 24 h protein diet. 102 34

In excised, curarized and massively stimulated fast-twitch mouse gastrocnemius muscles the early twitch tension enhancements (treppe) during 1/s activity between 10 and 36 degrees C increase and affect more contractions as temperature increases. Tension output eventually declines at a temperature-independent rate. Half-relaxation time lengthens below 25 degrees C and shortens above 25 degrees C. During 1/0.63s twitches half-relaxation time lengthens even at 25 degrees C. In slow-twitch soleus muscles activity decreases twitch tension and half-relaxation time regardless of temperature. Activity shortens contraction times in both muscles. Oxygen lack induced by NaN3 cannot account satisfactorily for these results. Activation is apparently more plastic in the gastrocnemius than in the soleus, and the relationship between the rates of their activation and relaxation processes and the temperature sensitivities of these rates also seem to differ. In both muscles caffeine can convert activity-induced shortened of half-relaxation times into prolongations. In the soleus this effect is more pronounced at 30 than at 25 degrees C. At high temperature and twitch rates caffeine reduces treppe amplitude and duration without affecting the eventual twitch tension decline in the gastrocnemius while it greatly accelerates twitch tension decline in the soleus. In both muscles intrafiber Ca2+ movements are apparently major determinants of fatigue behavior.
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PMID:Fatigue and caffeine effects in fast-twitch and slow-twitch muscles of the mouse. 103 14


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