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

Postoperative physiatric treatment is an integral part of the replacement of hips, knees, ankles, shoulders, elbows, wrists, and digital joints. Neuromuscular substitution patterns and incoordination usually prevail after joint replacement because of the usual long-term expectation and experience of pain, limitation of motion, fatigue, weakness, and the unavoidable operative trauma. The goals of postoperative physiatric treatment, in line with those of joint replacement surgery, are relief of pain and reestablishment of comfortable, normal neuromuscular functions and their reasonable, safe application in appropriate activities of daily living and of locomotion. By close collaboration between the Department of Orthopedic Surgery and that of Physical Medicine and Rehabilitation, certain principles and detailed protocols of postoperative management have been developed over the last 10 years. These are described in some detail for each of the joint replacements. Optimal results can be achieved only through meticulous attention to physical and psychosocial details, with close cooperation and communication among the involved services and persons.
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PMID:Total joint arthroplasty: principles and guidelines for postoperative physiatric management. 47 Apr 59

An optimal control strategy for FES-induced cyclical leg movements in paraplegics is proposed. The control of the cyclical movement of a freely swinging leg is considered as an example. Quadriceps and the flexion withdrawal reflex are stimulated in order to generate a cyclical movement, of which the forward swing resembles the swing phase of gait. Optimal stimulation patterns are determined on the basis of an optimization criterion and a dynamic model of the system. The criterion is based on desired movement parameters and a minimal duration of the stimulation bursts. The movement parameters should ensure the generation of the desired cyclical movement: a desired hip angle range, sufficient foot clearance during the forward swing and knee extension at the beginning of the backward swing. Minimal duration of the stimulation bursts is assumed to yield minimal fatigue. A dynamic model, describing the dynamics of the neural system, the muscles and the leg, was constructed and its parameters identified on the basis of preliminary experiments and literature. Optimal timing of the quadriceps and flexion reflex stimulation bursts was determined by means of computer simulation. These simulations predicted that the flexion reflex should be stimulated in a short burst approximately 150 ms before the start of the forward swing. The quadriceps should be stimulated approximately starting 200 ms before the end of the forward swing in order to ensure knee extension at the beginning of the backward swing. The duration of one cycle of the movement was between 1300 and 1500 ms in these simulations. These results predict that the movement specified by the functional objectives can be realised using only two channels of stimulation. On the basis of the optimal timing, an adaptive control strategy can be designed, which varies the stimulation burst width when muscles fatigue.
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PMID:Modelling the optimal control of cyclical leg movements induced by functional electrical stimulation. 149 50

In adult male hamsters the influence of emphysema (EMP) on the in vitro contractile and fatigue properties and the histochemical, morphometric, and metabolic properties of muscle fibers in the costal diaphragm was determined 6 mo after the administration of either elastase or saline (controls, CTL). Isometric contractile properties were determined in vitro using supramaximal direct muscle stimulation. Optimal fiber length for force generation was significantly shorter in the EMP than in the CTL diaphragm. Maximum specific force (i.e., force per unit area) was 25% lower than CTL. Fatigue resistance was significantly improved in the EMP diaphragm compared with CTL. Diaphragm muscle fibers were classified as type I or II on the basis of histochemical staining for myofibrillar adenosinetriphosphatase after alkaline preincubation. The proportions of type I and II fibers were similar between the two groups. Cross-sectional areas of type II fibers were 30% larger in EMP than in CTL diaphragms. Succinate dehydrogenase activities of both type I and II fibers were higher in EMP than in CTL diaphragms. The number of capillaries surrounding both type I and II fibers increased with EMP, but in proportion to the hypertrophy of these fibers. Thus, capillary density (number of capillaries per fiber cross-sectional area) remained unchanged. We postulate that these contractile, morphometric, and metabolic adaptations reflect an increased activation of the diaphragm in response to the loads imposed by EMP.
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PMID:Adaptations of the diaphragm in emphysema. 156 89

Although fats and protein contribute to energy demands of exercise, carbohydrate, principally glycogen, is the preferred fuel for muscular activity. Because of its limited storage, depletion of muscle glycogen has been shown to be one factor responsible for fatigue and exhaustion during prolonged exercise. Thus, dietary carbohydrate plays a key role in exercise performance and training. When the athlete's diet is low in carbohydrate, little glycogen is resynthesized between training sessions, leaving the individuals with low muscle glycogen and a state of chronic fatigue. The most sensitive period for glycogen resynthesis is within the first few hours after exercise. Optimal recovery from an exhaustive exercise bout depends on a reasonably rich carbohydrate diet soon after the exercise. Such feedings serve to replenish carbohydrate stores in both liver and muscles. Exertional hypoglycemia can occur when liver glucose output falls below the rate of muscle glucose uptake. Though this seldom occurs in well-fed and highly trained individuals, sugar feedings during long-term exercise has been shown to enhance performance. Thus, the important role of dietary carbohydrate before, during and after endurance activities is well established, whereas our understanding of the nutritional needs for protein and fat remain unclear.
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PMID:Carbohydrate for athletic training and performance. 181 89

Pericarbon, a new generation pericardial valve, is characterized by a single, three cuspal shaped pericardium sheet, which is sutured to a second sheet lining the inner surface of the plastic, low profile stent. A coating of hemocompatible carbon film covers all the exposed, nonbiological surfaces. Optimal preservation of collagen and graft cells is achieved by fresh tissue glutaraldehyde fixation and cusp shaping without mold. Accelerated fatigue testing showed a duration of over 150 million cycles, a figure much higher than that observed when current pericardial and porcine valves were tested with the same apparatus. Results of long-term (greater than 7 months, average 10.5) implantation in 20 sheep (13 mitral, 7 tricuspid) disclosed no case of mechanical failure, mild to moderate primary calcification in older explants, and significant fibrous tissue overgrowth only in the tricuspid position. Transmission electron microscopy studies revealed collagen and elastic fiber integrity, no significant plasma protein insudation, and well-preserved graft cells. Re-endothelialization by host cells was a regular finding on scanning electronic microscopy. Early ultrastructural nuclei of calcification were seen mostly on collagen fibers. Pericarbon presents basic changes in pericardial valve design, and optimal morphological preservation is obtained after industrial processing. Accelerated fatigue tests in vitro show long duration. At medium long-term animal experimental follow-up, mechanical failure was not observed; significant host tissue reaction occurred in the tricuspid but not in the mitral position; primary calcification increased progressively with time and involved mainly collagen fibers.
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PMID:Evaluation of Pericarbon valve prosthesis: in vitro, ultrastructural, and animal studies. 251 86

Acute lymphoblastic leukemia accounts for 80% of leukemia in children. The exact cause is unknown, but some genetic, immunologic, viral, and environmental factors have been implicated. Symptoms at the time of diagnosis frequently include fever, bleeding, fatigue, and irritability. Initial white blood cell count and patient age at diagnosis are the most reliable indicators of prognosis. Acute lymphoblastic leukemia is a heterogenous disease. Lymphoblast morphology, immunologic markers, enzyme abnormalities, cytogenetic findings, and staining characteristics in conjunction with clinical characteristics allow classification into risk groups. Appropriate therapy for each risk group is based on these parameters. Combination chemotherapy administered alone or with additional chemotherapy or radiotherapy to sanctuary sites is the principal modality for treatment of ALL. Optimal therapy for relapse has not yet been determined, but for patients with appropriate donors, allogeneic bone marrow transplant is promising. Common complications of chemotherapy include tumor lysis syndrome, myelosuppression, and other problems such as gastrointestinal toxicity, neurotoxicity and cardiac toxicity. Significant late effects of chemotherapy include neurological impairment ranging from learning problems to leukoencephalopathy and a possible increased risk of second malignancy. Complete remission is achieved in 95% of children with acute lymphoblastic leukemia, and more than 55% will continue to be in complete remission at five years. Optimal CNS prophylaxis, effective treatment of relapse, and adjustment of therapy to minimize acute and late adverse effects are a continuing challenge. With improved understanding of biologic factors, and development of more specific therapy for each subgroup, children with acute lymphoblastic leukemia should enjoy a better long term outcome.
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PMID:Childhood acute lymphoblastic leukemia. 328 Nov 3

Alpha interferons are biological response modifiers that regulate immune function, slow cell proliferation, and inhibit virus replication. Large supplies of purified preparations are now available for clinical trials. Common toxicity includes an influenza-like syndrome to which tolerance occurs after several doses, and chronic fatigue and anorexia that may be dose-limiting. Myelosuppression is mild. Alpha interferons have established clinical activity against several human cancers, including melanoma, Kaposi's sarcoma, multiple myeloma, non-Hodgkin's lymphoma, hairy cell leukemia, and renal cell carcinoma. These data and alpha interferon nomenclature are summarized in table form. Intranasal alpha interferon is effective in prophylaxis of common viral upper respiratory tract infections, although toxicity in long-term use is prohibitive. Short-term administration to high risk populations may be most useful. Optimal doses and schedules need to be determined for all indications.
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PMID:The new alpha interferons. 391 Mar 84

The new synthetic opioid Tramadol [1-(m-Methoxyphenyl)-2-(dimethylaminomethyl)-cyclohexane-1-ol] was examined in 30 patients with different malignant diseases. An excellent or sufficient pain relief could be found in 86%. Only 14% of all patients did not respond. The analgetic effect throughout the day could be observed in most cases (92%) after the application of maximally 200 mg/die. Optimal or moderate subjective tolerance was found in 95% of all cases. Fatigue (65.8%), dryness of the mouth (68.4%), dizziness (14.3%) and perspiration (12.2%) were the main side effects. For this reason Tramadol can be recommended as a highly useful analgesic drug in the treatment of tumor induced pain.
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PMID:[Analgesic effect of tramadol in patients with malignant diseases]. 637 16

In acute hyperinflation, the occurrence of diaphragmatic shortening may alter the contractile characteristics and function of the diaphragm. The aim of this study was to investigate the effects of acute passive diaphragmatic shortening on in vitro mechanical properties and fatigability. Optimal diaphragmatic length (Lo) was defined as being that length at which peak twitch-tension occurred. Acute shortening (85% Lo, 70% Lo) altered the twitch characteristics. At shorter lengths, the time-to-peak tension and the half-relaxation time were significantly reduced (p less than 0.05). These alterations led to marked alterations in the shape of the force-frequency curve at shorter lengths and in the length-tension properties when assessed at different stimulation frequencies. When normalized with respect to maximal tension, a disproportionate decrease in the generated tension was observed at shorter lengths. Fatigability was assessed by repeatedly stimulating the diaphragmatic bundles and observing the drop in tension with respect to time. For a given fatigue regimen, i.e., same stimulation frequency, the shorter diaphragm (70% Lo) generated more absolute force at any given time period. When the initial tensions were matched at Lo and 70% Lo by increasing the stimulation frequency used to fatigue the shorter muscle, the acutely shortened diaphragm generated less absolute force following 60 s of the fatigue regimen. We conclude that alterations in the contractile characteristics of the diaphragm during acute passive shortening are such that a disproportionately greater excitability is required in order to reach a given submaximal tension as at Lo. This factor may partly account for increased diaphragmatic fatiguability in the acutely shortened state.
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PMID:Acute diaphragmatic shortening: in vitro mechanics and fatigue. 647 94

Corynebacterium equi, an aerobic, variably acid-fast, gram-positive "diphtheroid," is an unusual cause of pulmonary infection in immunosuppressed patients. Initially, infection with C. equi may be mistaken for a mycobacterial infection. Two cases in a two-year period were observed and compared with the 10 cases previously reported in the literature. All but one patient had pulmonary involvement, and the presentation of all other patients was typically insidious, with fatigue, fever, and nonproductive cough. Chest roentgenograms showed cavitary lesions in seven of 11 patients. Four of 12 patients had associated bacteremias, and three of 12 had subcutaneous abscesses or lymphadenitis. One of our patients developed multiple brain abscesses. Overall mortality was 25%. The organism is susceptible to vancomycin, erythromycin, aminoglycosides, and chloramphenicol. Optimal duration of antibiotic therapy and the proper role of surgery in treatment is uncertain, but relapses have been common and many weeks of antibiotic therapy have generally been required for cure.
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PMID:Corynebacterium equi: a review of 12 cases of human infection. 665 80


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