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

The present study was designed to determine the contribution of weight bearing to the adaptations of the plantaris (PL) to synergist removal. PL from female rats were exposed to 28 days of a simultaneous condition of synergist ablation and hindlimb suspension. At 28 days, contractile responses and morphological measures were obtained and compared with muscles that either had synergists intact or were weight bearing or a combination of both. Synergist ablation prolonged PL maximum isometric twitch tension (Pt), time to peak tension (12%), and one-half relaxation time (12%); increased Pt (26%), maximum isometric tetanic tension (Po, 44%), fatigue resistance (FI, 42%), and fast fiber cross-sectional area (FT CSA, 20%); and decreased Pt/Po (13%) over nonablation counterparts. Suspension decreased PL Pt (26%), Po (26%), rest length (16%), FT CSA (31%), and slow-twitch fiber (ST) number (24%) but increased FI (75%) over weight-bearing counterparts. PL from weight-bearing animals were heavier than from suspended animals, and the extent of this response was greatest after synergist removal. Whole muscle and ST CSA and ST area contribution were greater only in weight-bearing synergist ablation muscles. Daily weight bearing (4 h) in synergist ablation hindlimb suspension groups caused PL weights and ST expressions to be halfway between 24-h suspension and 24-h weight-bearing groups. Our results suggest that weight bearing is not essential to the induction of several adaptations associated with synergist ablation but is required to cause the large muscle mass and ST expression characteristic of this model.
 ...
PMID:Influence of weight bearing on the adaptations of rat plantaris to ablation of its synergists. 279 64

The electrically evoked isometric properties of the triceps surae have been studied in young (22 yr) and elderly (69 yr) men and women. The results show that the triceps surae of elderly subjects had an increased time to peak tension (TPT) of the twitch, a lower specific tension (force/cross section area), and showed a greater relative force loss when subjected to a standard "fatigue" test procedure than young triceps surae. The respective figures for TPT, specific tension, and fatigue index (FI) were 147 +/- 15 ms (male), 143 +/- 8 ms (female), 19.5 N/cm2 and 0.52 +/- 0.16 (male), 0.37 +/- 0.09 (female) in the elderly, compared with 118 +/- 14 ms (male), 132 +/- 11 ms (female), 32.9 N/cm2 and 0.67 +/- 0.11 (male), 0.62 +/- 0.09 (female) in their younger counterparts. The peak rates of rise (delta P50, delta P200) and relaxation (delta PR50, delta PR200) of tetani at 50 Hz and 200 Hz were slower (p less than 0.05) in the elderly group. The delta P50 and delta P200 were inversely associated (r = 0.76 and -0.50 respectively) with TPT, and the half relaxation time (1/2RT) of the maximal twitch was related to delta PR50 (r = 0.53). The decrease of tetanus relaxation rate during the 2 min fatigue test (delta PRF) was greater in the elderly than the young and was positively associated (r = 0.74) with FI. It is concluded that elderly muscle is weaker, more slowly contracting and fatigable than that of the young. However, it is suggested that the reduced specific tension and enhanced fatiguability of the elderly may in part be due respectively to the inadequacies of our estimates of the effective cross-sectional area CSA) of contractile tissue in the lower leg and the influence of blood flow which may be compromised during a 2 min test.
 ...
PMID:Mechanical properties of young and elderly human muscle. 346 6

A previous uncontrolled study suggested that nasal continuous positive airway positive airway pressure (NCPAP) may improve left ventricular ejection fraction (LVEF) in patients with congestive heart failure (CHF) and Cheyne-Stokes respiration with central sleep apnea (CSR-CSA). In order to more critically evaluate the effects of NCPAP on cardiac function, we undertook a randomized, controlled trial of NCPAP in 29 patients with heart failure and CSR-CSA over a 3-mo period, with LVEF as the primary outcome measure. Patients with CHF and associated CSR-CSA who were receiving optimal medical therapy were randomly assigned to a control group (n = 15) or a group receiving nightly NCPAP (n = 14). Twelve patients in each group completed the study. There was a greater improvement of LVEF in the NCPAP group than in the control group during the study (mean +/- SEM = 7.7 +/- 2.5 versus - 0.5 +/- 1.5%, p = 0.019). In addition, there was a significantly greater reduction in the number of apneas and hypopneas (-28.5 +/- 3.9 versus -6.1 +/- 7.0 per hour of sleep, p = 0.012) in the NCPAP group than in the control group. Significantly greater improvements in symptoms of fatigue (5.6 +/- 1.2 versus 0.8 +/- 0.7, p = 0.005) and disease mastery (3.6 +/- 1.1 versus -0.7 +/- 0.7, p = 0.031) were also observed in the NCPAP group. We conclude that in patients with chronic heart failure and CSR-CSA, nightly administration of NCPAP can attenuate CSR-CSA, improve cardiac function, and alleviate symptoms of heart failure.
 ...
PMID:Treatment of congestive heart failure and Cheyne-Stokes respiration during sleep by continuous positive airway pressure. 781 79

Patients with congestive heart failure (CHF) suffer from respiratory muscle weakness which may contribute to dyspnea. Nasal continuous positive airway pressure (NCPAP) can improve left ventricular ejection fraction (LVEF) and reduce dyspnea in patients with CHF and Cheyne-Stokes respiration with central sleep apnea (CSR-CSA) but its effects on respiratory muscle strength are not known. We therefore studied the effects of NCPAP on maximal inspiratory and expiratory pressures (MIP and MEP, respectively), LVEF, dyspnea, and fatigue in patients with chronic CHF and CSR-CSA over 3 mo. Eight patients were randomized to control and nine to nightly NCPAP. There were no significant changes in any of these factors in the control group during the study. In contrast, among the NCPAP group, MIP increased from 79.3 +/- 8.1 to 90.7 +/- 10.4 cm H2O (mean +/- SEM; p < 0.02), LVEF increased from 24.0 +/- 4.0 to 32.6 +/- 6.6% (p < 0.02) and symptoms of dyspnea and fatigue were alleviated. However, MEP did not change. In addition, the number of apneas and hypopneas decreased from 49 +/- 11 to 17 +/- 7 per hour of sleep (p < 0.001) and mean low Sao2 during sleep increased from 87.9 +/- 1.0 to 93.0 +/- 1.0% (p < 0.01). Our data indicate that nightly application of NCPAP in patients with CHF and CSR-CSA improves inspiratory muscle strength and LVEF, and relieves dyspnea and fatigue.
 ...
PMID:CPAP improves inspiratory muscle strength in patients with heart failure and central sleep apnea. 854 29

The myosin heavy chain (MHC) exists as multiple isoforms that are encoded for by a family of genes. The respiratory musculature demonstrates muscle-specific and temporally-dependent changes in MHC isoform expression during maturation. Developmental expression of MHC isoforms correlate well with postnatal changes in actomyosin ATPase activity, specific force generation (P0/CSA), maximum unloaded velocity of shortening (V0) and and fatigue resistance. More specifically, as the expression of MHCneonatal declines and MHC2A, MHC2X, and MHC2B increase, actomyosin ATPase activity, P0/CSA, V0, and muscle fatigability increase. The increase in actomyosin ATPase activity with maturation is partially offset by a postnatal increase in oxidative capacity; however, as fatigue resistance declines with development it is apparent that the energy costs of contraction are not fully matched by an increase in energy production. Developmental transitions in smooth muscle MHC phenotype also occur although their functional importance remains unclear.
 ...
PMID:Myosin heavy chain transitions during development. Functional implications for the respiratory musculature. 973 30

Exercise-induced oxidative stress has been reported in patients with chronic obstructive pulmonary disease (COPD) and may play a role in muscle fatigue. It is speculated that oxidative stress during exercise originates from the contracting muscles but this has not been documented. The accumulation of lipofuscin, a marker of cellular oxidative damage, was evaluated in the vastus lateralis muscle in 17 patients with COPD and 10 healthy subjects of similar age. Each subject performed a stepwise exercise test up to maximal capacity during which oxygen uptake (VO(2)) was measured. Resting and peak exercise blood gases were also obtained. Two indices of lipofuscin accumulation were used: lipofuscin inclusions/fiber ratio (LI/F) and lipofuscin inclusions/fiber cross-sectional area ratio (LI/CSA). These ratios were also determined for each specific fiber-type. LI/F (P < 0.01) and LI/CSA (P < 0.01) were greater in COPD compared to healthy subjects. LI/F and LI/CSA for all fiber types were also greater in COPD (P < 0.001). In both groups, LI/F (P < 0.001) and LI/CSA (P < 0.01) were higher in type I than in type II fibers. LI/F and LI/CSA did not correlate significantly with resting PaO(2) and SaO(2), peak VO(2), and DeltaPaO(2) and DeltaSaO(2) during exercise (P > 0.05). Increased lipofuscin accumulation, a marker of oxidative damage, was found in the vastus lateralis muscle in patients with COPD compared to healthy subjects. Oxidative damage of muscle tissue may thus be involved in skeletal muscle dysfunction and wasting in COPD.
 ...
PMID:Lipofuscin accumulation in the vastus lateralis muscle in patients with chronic obstructive pulmonary disease. 1187 Jul 15

Individuals with chronic fatigue syndrome (CFS) have been shown to have reduced activity levels associated with heightened feelings of fatigue. Previous research has demonstrated that exercise training has beneficial effects on fatigue-related symptoms in individuals with CFS. PURPOSE: The aim of this study was to sustain an increase in daily physical activity in CFS patients for 4 weeks and assess the effects on fatigue, muscle pain and overall mood. METHODS: Six CFS and seven sedentary controls were studied. Daily activity was assessed by a CSA accelerometer. Following a two week baseline period, CFS subjects were asked to increase their daily physical activity by 30% over baseline by walking a prescribed amount each day for a period of four weeks. Fatigue, muscle pain and overall mood were reported daily using a 0 to 100 visual analog scale and weekly using the Profile of Mood States (Bipolar) questionnaire. RESULTS: CFS patients had significantly lower daily activity counts than controls (162.5 +/- 51.7 x 103 counts/day vs. 267.2 +/- 79.5 x 103 counts/day) during a 2-week baseline period. At baseline, the CFS patients reported significantly (P < 0.01) higher fatigue and muscle pain intensity compared to controls but the groups did not differ in overall mood. CFS subjects increased their daily activity by 28 +/- 19.7% over a 4 week period. Overall mood and muscle pain worsened in the CFS patients with increased activity. CONCLUSION: CFS patients were able to increase their daily physical activity for a period of four weeks. In contrast to previous studies fatigue, muscle pain, and overall mood did not improve with increased activity. Increased activity was not presented as a treatment which may account for the differential findings between this and previous studies. The results suggest that a daily "activity limit" may exist in this population. Future studies on the impact of physical activity on the symptoms of CFS patients are needed.
 ...
PMID:Increased daily physical activity and fatigue symptoms in chronic fatigue syndrome. 1574 55

The purpose of this study is two-fold: (1) to examine skeletal muscle function in a rat model of midthoracic contusion spinal cord injury (SCI) and (2) to evaluate the therapeutic influence of a short bout (1 week) of treadmill locomotor training on soleus muscle function (peak force, fatigability, contractile properties, fiber types), size (fiber area), and motor deficit and recovery (BBB scores) after SCI. The rats were injured with a moderate T8 spinal cord contusion and were assigned to either receive treadmill locomotor training (TM), starting 1 week after SCI for 5 consecutive days (20 min/trial, 2 trials/day) or not to receive any exercise intervention (no TM). Locomotor training resulted in a significant improvement in overall locomotor function (32% improvement in BBB scores) when compared to no TM. Also, the injured animals that trained for 1 week had 38% greater peak soleus tetanic forces (p < 0.05), a 9% decrease in muscle fatigue (p < 0.05), 23% larger muscle fiber CSA (p < 0.05), and decreased immunoexpression of fast heavy chain fiber types than did rats receiving no TM. In addition, there was a good correlation (0.704) between the BBB scores of injured animals and peak soleus muscle force regardless of group assignment. No significant differences were seen in twitch or time to peak tension values across groups. Collectively, these results indicate that 1 week of treadmill locomotor training, initiated early after SCI, can significantly improve motor recovery following SCI. The magnitude of these changes is remarkable considering the relatively short training interval and clearly illustrates the potential that initiating treadmill locomotor training shortly after injury may have on countering some of the functional deficits resulting from SCI.
 ...
PMID:Changes in soleus muscle function and fiber morphology with one week of locomotor training in spinal cord contusion injured rats. 1711 12

Obstructive sleep apnea (OSA), which is characterized by recurrent upper airway obstruction during sleep with resultant hypoxia-reoxygenation and sleep fragmentation, is prevalent among patients with cardiovascular disease. Refractory hypertension, nocturnal angina or arrhythmias, and stroke in particular should prompt consideration of OSA. The symptoms of OSA include snoring and excessive daytime sleepiness; risk factors include obesity and reduced upper airway dimensions. Up to 50% of patients with congestive heart failure (CHF) may manifest OSA, central sleep apnea-Cheyne-Stokes respiration (CSA-CSR), or both. Patients with CSA-CSR may present with fatigue, disrupted sleep, and paroxysmal nocturnal dyspnea. Objective sleep recording is required to document the nature and severity of sleep apnea. The gold standard is in-laboratory overnight polysomnography (PSG), including monitoring of electroencephalography and other signals to determine sleep-wake state, and recording of body position, airflow, respiratory effort, and pulse oximetry. Portable cardiorespiratory recorders are now approved for diagnosis in patients without comorbidities. Full PSG is recommended for diagnosis in all other cases, although OSA and CSA-CSR can be identified from portable recorders in some patients with CHF and other conditions. The objectives of treatment are to improve symptoms, quality of life, and cardiovascular outcomes. The mainstay of treatment for moderate-to-severe OSA is positive airway pressure (PAP). Automated PAP devices may be used in uncomplicated OSA, whereas continuous fixed PAP is the treatment of choice for other patients with OSA, and may also treat a proportion of patients with CSA-CSR. A form of bi-level PAP known as adaptive servoventilation is effective in treating a majority of patients with CSA-CSR.
...
PMID:When to Suspect Sleep Apnea and What to Do About It. 2611 5

The goal of treating sleep disordered breathing (SDB) has traditionally focused on improving daytime sleepiness and fatigue. In heart failure (HF) patients with SDB, this is not as easy to ascertain as their symptoms overlap with HF. Thus, improvement in treating SDB in HF patients must focus more on overall quality of life. Over the past 5 years, there has been a shift in sleep medicine from only improving symptoms in SDB, to preventing the long term consequences. The specialist Heart Failure community is, however, desirous of also seeing benefit in reduction of major clinical events for their patients with interventions, such as effects on mortality or re-hospitalisation rates and so may wish to see other benefits beyond a reduction in sleep apnea events before either commencing therapy or referring their patients for sleep study evaluation and further management. To expect lower mortality as well may be asking for too much. Consequently, success in the treatment in SDB should focus on three items: 1) proof that the underlying disease is treated, 2) symptomatic benefit and 3) demonstration that the pathological consequences are prevented. These benefits must then be balanced with a strong safety profile. Here we evaluate a variety of end-points of value to our CSA patients, in an effort to see what may reasonably be required for treating physicians to recommend an intervention for their CHF patients with CSA by looking at candidate measures of treatment success in CSA within a heart failure population.
 ...
PMID:Measuring therapeutic efficacy in the treatment of central sleep apnoea in patients with heart failure. 2697 Nov 85


1 2 Next >>