Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0015672 (fatigue)
 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Atrial fibrillation is most the common sustained arrhythmia seen by the cardiologist. Therapy to prevent this arrhythmia is often prescribed so as to eliminate associated symptoms which include palpitations, fatigue, dizziness and presyncope, shortness of breath, congestive heart failure and emboli, especially those that result in a cerebrovascular accident. Pharmacologic therapy is the only effective therapy for preventing atrial fibrillation and the class 1 antiarrhythmic drugs remain the most frequently used agents. Although each of these agents has been reported to be effective for preventing atrial fibrillation, they are associated with frequent side effects, some of which are potentially serious, especially aggravation of arrhythmia. Prior to treatment the benefit vs risk of these drugs for each patient must be established.
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PMID:Class 1 antiarrhythmic agents for therapy of atrial fibrillation. 845 55

This study describes shoulder muscle activity during the butterfly stroke. Upon hand entry, the deltoids and rotator cuff muscles demonstrated activity as the humerus was abducted, extended, and externally rotated. The rhomboids and upper trapezius were also active, retracting and upwardly rotating the scapula, which positioned the glenoid for the humerus. During propulsion, the pectoralis major and latissimus dorsi generated power. The subscapularis and teres minor were active to control humeral rotation. The serratus anterior helped to pull the body over the arm by reversing its origin and insertion. The posterior deltoid completed humeral extension at the end of propulsion and began to lift the arm out of the water. Then, the middle and anterior deltoids fired with the supraspinatus and infraspinatus to abduct and externally rotate the arm. The scapular muscles were also active, retracting the proximal portion of the scapula while protracting and upwardly rotating the distal tip. The glenoid then provided a platform for the humerus. Overall, the serratus anterior and the subscapularis maintained a high level of activation throughout the stroke; thus, these muscles were highly susceptible to fatigue and vulnerable to injury.
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PMID:The normal shoulder during the butterfly swim stroke. An electromyographic and cinematographic analysis of twelve muscles. 845 54

1. Heat acclimation was induced in eight subjects by asking them to exercise until exhaustion at 60% of maximum oxygen consumption rate (VO2) for 9-12 consecutive days at an ambient temperature of 40 degrees C, with 10% relative humidity (RH). Five control subjects exercised similarly in a cool environment, 20 degrees C, for 90 min for 9-12 days; of these, three were exposed to exercise at 40 degrees C on the first and last day. 2. Acclimation had occurred as seen by the increased average endurance from 48 min to 80 min, the lower rate of rise in the heart rate (HR) and core temperature and the increased sweating. 3. Cardiac output increased significantly from the first to the final heat exposure from 19.6 to 21.4 l min-1; this was possibly due to an increased plasma volume and stroke volume. 4. The mechanism for the increased plasma volume may be an isosmotic volume expansion caused by influx of protein to the vascular compartment, and a sodium retention induced by a significant increase in aldosterone. 5. The exhaustion coincided with, or was elicited when, core temperature reached 39.7 +/- 0.15 degrees C; with progressing acclimation processes it took progressively longer to reach this level. However, at this point we found no reduction in cardiac output, muscle (leg) blood flow, no changes in substrate utilization or availability, and no recognized accumulated 'fatigue' substances. 6. It is concluded that the high core temperature per se, and not circulatory failure, is the critical factor for the exhaustion during exercise in heat stress.
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PMID:Human circulatory and thermoregulatory adaptations with heat acclimation and exercise in a hot, dry environment. 848 4

A double chamber ventricular assist device (VAD) with a roller screw linear muscle actuator (RSLMA) driven by the left and right latissimus dorsi muscles was developed. The inflow port of each chamber was connected to form the compound inflow port, and the outflow ports were connected to form the compound outflow port. The advantages of this system include 1) the contraction of each muscle contributes to ejection from each ventricle into the common outflow port, thus doubling the net outflow; 2) through proper adjustment of muscle length, the preload to each muscle can be optimized to yield the maximum muscle force; 3) muscle can be stimulated at a lower rate to reduce fatigue and to optimize muscle performance; and 4) the compliance chamber needed in the implantable VAD system is not required with this system. In vitro evaluation in the mock loop with the human arm actuating the RSLMA revealed that the double chamber VAD can provide pump flows of 2-4 L/min against an afterload of 100 mmHg at a stimulation rate of 35-50 beats per minute. The power requirement for each muscle ranged from 2.5 to 3 W at a muscle stroke length of 4 cm. These results verify that the double chamber VAD with the RSLMA driven by the left and right latissimus dorsi muscles can meet the design requirements of a muscle driven VAD to assist the left heart.
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PMID:Double chamber ventricular assist device with a roller screw linear actuator driven by left and right latissimus dorsi muscles. 857 50

To evaluate the in situ latissimus dorsi muscle as an actuator for circulatory assistance, 1) muscle power was analyzed in animal experiments, and 2) muscle weight was measured in human cadavers. Three adult goats underwent 12 week preconditioning. The insertion of the latissimus dorsi muscle was then connected to a spring and a tension transducer in series. The stroke length was measured with a photosensor without power loss. With contraction of muscles under various loads, tension-length relationships at end contraction and end relaxation were obtained and the maximum area of a square drawn within both lines was assumed to be maximum external power. Good fatigue resistance and the highest maximum external power of 3.16 Watts/kg at 120 min was derived from preconditioned latissimus dorsi muscle in burst frequency of 50 Hz. Muscle weight in 42 human cadavers was negatively correlated with age (r = 0.56) and was expected to be 221.6 g in patients aged 45 years. According to these data, the power of a human preconditioned latissimus dorsi muscle was estimated as 0.7 Watts. It was concluded the power of in situ preconditioned latissimus dorsi muscles was appropriate for right heart assistance or counterpulsation for left heart assist.
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PMID:Power of the fatigue resistant in situ latissimus dorsi muscle. 857 10

Clinical experience suggests that the visual neglect in stroke patients fluctuates over short periods of time. This fluctuation has been variously attributed to fatigue, time of day, previous activities, patient learning and compensation. Such fluctuations have clinical implications for the assessment and rehabilitation of visual neglect but do date no formal study has evaluated the extent of such fluctuation over the course of a day. Twenty-two patients with an acute stroke and 19 patients with convalescent stroke were examined for visual neglect twice on the same day using the Visual Neglect Recovery Index (VNRI), a valid and sensitive measure of the severity of neglect, which could be used to select acute patients for trials of treatment of neglect. The inter-test reliability was extremely high. In contrast to past clinical accounts most patients failed to show significant fluctuation. Although preliminary, this finding suggests that a single assessment of visual neglect, using the VNRI, could help select patients for treatment trials.
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PMID:Fluctuations in visual neglect after stroke? 859 1

We investigated the upright bicycle exercise cardiopulmonary response in 20 patients with left ventricular dysfunction (LVD, secondary to previous myocardial infarction, left ventricular ejection fraction range 18-44%). Ten patients (48 +/- 7 years) asymptomatic (I NYHA class) without drug treatment (LVD group). The others (n = 10) (50 +/- 1 years) complained of dyspnea and/or fatigue despite therapy (NYHA II-III). They represented the heart failure (HF) group. Eight sedentary men (40 +/- 10 years) served as controls. Controls and patients performed stress testings under drug treatment, when administered. Anaerobic ventilatory threshold (ATge) was considered as an index of submaximal exercise while peak exercise VO2 (Peak VO2) was considered the maximal volitional exercise capacity. The ratio between minute ventilation (VE) to carbon dioxide release (VCO2) (VE/VCO2) was assessed to evaluate the ventilatory response during exercise. We coupled gas exchange assessment (2001, MGC) with noninvasive monitoring of stroke volume (SV) by impedance cardiography (NCCOM3, BOMED) and total systemic vascular resistances (TSVR; by auscultatory blood pressure measurement). In controls VO2 increase during exercise was related to higher heart rate (HR) and SV both from resting to ATge and from this point to the peak. TSVR declined during both steps. In patients with HF VO2 rose from resting to ATge (by faster HR and unchanged SV). VO2 increased slightly from this point to Peak VO2. This result was related to flat HR increase and unchanged SV as well as TSVR. In patients with LVD VO2 increased similarly to controls from resting to ATge and less above the threshold. In these patients both HR and SV increased during submaximal exercise. From ATge to Peak VO2 only HR increased. TSVR declined significantly similarly to controls. The VE/VCO2 ratio was higher at peak exercise in patients with HF compared to controls. Different determinants were demonstrated in patients with left ventricular dysfunction with mild or symptomatic chronic heart failure (CHF). These findings and the increased ventilatory response in patients with CHF can explain different changes of VO2 in these patients during submaximal and maximal voluntary exercise and contribute to explain exercise-induced exertion in these subjects.
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PMID:Cardiopulmonary exercise response in patients with left ventricular dysfunction or heart failure: a noninvasive study by gas exchange and impedance cardiography monitoring. 865 32

During December 1993-September 1995, the Bureau of Food and Drug Safety, Texas Department of Health (TDH), received approximately 500 reports of adverse events in persons who consumed dietary supplement products containing ephedrine and associated alkaloids (pseudoephedrine, norephedrine, and N-methyl ephedrine). This total included reports by individuals and reports identified by the Bureau of Epidemiology, TDH, in a review of records from the six centers of the Texas Poison Center Network. Reported adverse events ranged in severity from tremor and headache to death in eight ephedrine users and included reports of stroke, myocardial infarction, chest pain, seizures, insomnia, nausea and vomiting, fatigue, and dizziness. Seven of the eight reported fatalities were attributed to myocardial infarction or cerebrovascular accident. This report describes three patients in which the recommended dosage for the dietary supplements reportedly was not exceeded, summarizes results from ongoing investigations, and underscores the potential health risks associated with the use of products containing ephedrine.
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PMID:Adverse events associated with ephedrine-containing products--Texas, December 1993-September 1995. 877 3

Two 29 mm St. Jude Medical valves, two 29 mm CarboMedics valves and two 29 mm Sorin Bicarbon valves were tested in a real time fatigue test rig. The test rig was run at 72 beats/min with a stroke volume of 70 ml for approximately one million cycles. Optical microscopy was used to investigate the valve surfaces. Possible deterioration of the surface finish was observed on the stops of the hinge recesses in the St. Jude Medical and CarboMedics valves. In the Sorin valves areas of the pyrolytic carbon coating was worn away adjacent to and on the valve stops.
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PMID:An initial investigation into the wear and damage within the pivots of three types of bileaflet mechanical heart valves. 880 63

Competitive swimmers perform highly repetitive motions, therefore characteristic overuse injuries of the shoulder, back, and knee can occur. A thorough history and examination should be performed by both physician and physical therapist. The combination of hypovascularity, fatigue, poor stroke mechanics, and the progressive instability of a hypermobile joint results in shoulder impingement. Medical evaluation should determine the existence of any glenohumeral joint instability or signs of impingement. Back injuries are most commonly due to disc degeneration, hyperextension, or myofascial involvement. Medial knee pain is most common in breaststroke swimmers and may be due to excessive valgus and rotatory stress. Frequently seen diagnosis includes patellofemoral pain, medial collateral ligament stress syndrome, and medial synovitis. Treatment will focus on elimination of inflammation. Rehabilitation should focus on stabilisation exercises for hypermobile joints, postural correction, strengthening and flexibility.
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PMID:Rehabilitation of injuries in competitive swimmers. 892 51


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