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

The main purpose of this study was to characterize brain activation patterns during a fatigue task involving repetitive maximal voluntary contractions (MVC) of finger flexor muscles. Fourteen young, healthy human participants performed approximately 100 handgrip MVCs (each 2-s contraction was followed by a 1-s rest) while their brain was imaged by functional MRI (fMRI). The handgrip force and electromyograms (EMG) of the finger flexors declined progressively to about 40% of the initial values at the end of the fatigue task, suggesting that significant muscle fatigue had occurred. In contrast, the level of the fMRI signal in the primary (sensorimotor), secondary (supplementary motor), and association (prefrontal and cingulate) motor-function cortices did not change significantly throughout the fatigue task (although the signal of the primary sensorimotor cortex showed a clear trend of decline). The fMRI data from the task of intermittent handgrip MVCs differed dramatically from those obtained in a 2-min sustained handgrip MVC published in a recent report, in which the overall fMRI-measured brain activation level was substantially lower and followed an increase-then-decrease pattern compared to the linear decreases in force and EMG. These results support the notion that the motor cortical centers control the tasks of repetitive and continuous muscle contractions differently and that there is a decoupling in the signal changes of the brain and muscles during muscle fatigue processes induced by maximal voluntary contractions.
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PMID:Fatigue induced by intermittent maximal voluntary contractions is associated with significant losses in muscle output but limited reductions in functional MRI-measured brain activation level. 1580 25

October 2004. A 49-year-old right-handed man developed progressive cognitive difficulties over a 4-month period. There was impairment in recent memory, calculations and language. He also developed fatigue, weight loss, gait imbalance and urinary incontinence. Past history included transfusion-associated Hepatitis C. Neurologic exam showed mild dysarthria, dysnomia, left sided neglect, bilateral Babinski signs, and a prominent grasp reflex. Laboratory testing provided no positive etiologic data. An EEG showed generalized intermittent slowing suggestive of a diffuse encephalopathy and decreased background in the right hemisphere, suggestive of a structural lesion. MRI showed multiple areas of high signal on FLAIR imaging and patchy enhancement. FDG-PET showed multi-focal areas of increased uptake, correlating with the abnormal areas on MRI, on a background of decreased uptake. A 4-vessel cerebral angiogram showed no abnormalities. A brain biopsy showed diffuse infiltrates of large malignant cells that were immunoreactive with antibodies to CD20, diagnostic of diffuse large B cell lymphoma. In summary, the clinical presentation suggested bilateral hemispheric involvement, which was supported by physical examination, EEG, MRI, and PET scans. The differential diagnosis for this presentation is limited to demyelinating disease such as multiple sclerosis, vascular dementia, and infiltrating neoplasm such as glioblastoma multiforme or lymphoma. Diagnosis was made by morphologic and immunohistochemical analysis of brain tissue.
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PMID:October 2004: a 49-year-old man with progressive dementia. 1591 74

The family of VEGF receptors are important mediators of angiogenesis, which is essential for tumour growth and metastasis. PTK/ZK is a multiple VEGF receptor inhibitor that blocks the activity of all known VEGF receptor tyrosine kinases. This phase I/II trial evaluated the safety, pharmacokinetics and efficacy of PTK/ZK in patients with liver metastases from solid tumours. Patients were administered oral PTK/ZK monotherapy once daily at doses of 300-1200 mg/day in 28-day cycles until unacceptable toxicity or tumour progression occurred. Twenty-seven patients were enrolled and treatment with PTK/ZK was generally well tolerated. The most frequently reported adverse events were fatigue, nausea, dizziness, and vomiting (mostly National Cancer Institute Common Toxicity Criteria grade 1 or 2). The area under the concentration-time curve (AUC) of PTK/ZK increased between 300 and 1000 mg/day with no further increase from 1000 to 1200 mg/day; the AUC decreased by 50% between day 1 and day 15. The DCE-MRI showed a statistically significant early reduction of tumour blood supply (measured as Ki) at day 2 at doses > or = 750 mg/day. Disease progression was significantly correlated with percent change from baseline Ki. Thirteen patients had stable disease for at least two cycles (56 days). Median overall survival was 11.8 months (95% CI = 6.6, 17.1 months). Long-term therapy with PTK/ZK demonstrated predictable pharmacokinetics, was safe and feasible in patients with metastatic disease, and showed promising clinical activity. The minimum biologically active dose was established at 750 mg/day whereas the recommended dose for phase III studies is 1200 mg/day.
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PMID:Phase I clinical and pharmacokinetic study of PTK/ZK, a multiple VEGF receptor inhibitor, in patients with liver metastases from solid tumours. 1593 65

We have compared functional MRI signals in primary sensorimotor cortex (SM1) during a paced motor task of each hand before and after unimanual (right hand) fatiguing exercise. Our aims were to determine whether the degree of activation is different when a motor task is performed after a fatiguing exercise, and whether there are any differences in activation between movement of the fatigued and non-fatigued hands. There was a significant reduction in the number of voxels activated in SM1 in the hemisphere contralateral to movement of both the fatigued hand (38 +/- 5 pre-exercise versus 21 +/- 3 post-exercise; P<0.05) and the non-fatigued hand (32 +/- 4 pre-exercise vs 18 +/- 4 post-exercise; P<0.05). There was no significant difference in the magnitude of the functional magnetic resonance imaging signal before or after exercise, however, the variance increased significantly after exercise (6.0 +/- 0.5 pre-exercise vs 7.3 +/- 0.6 post-exercise; P<0.01). Reduced functional activation in SM1 may reflect increased variability in the activation rather than a reduction in activation of cortical motor networks after fatigue.
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PMID:Primary sensorimotor cortex activation with task-performance after fatiguing hand exercise. 1603 78

The study of mechanics of the temporomandibular joint (TMJ) is important because its dysfunction and breakdown could be, at least partially, of mechanical origin. The incongruity of the articular surfaces of the TMJ is compensated by a fibrocartilaginous articular disc. Its dislocation and failure seem to be closely related to the development of osteoarthritis of the TMJ. The analysis of mandibular kinematics permits the detection and assessment of irregularities of TMJ function due to internal obstacles such as a displaced articular disc. Furthermore, the measurement of the dynamic relationship between the articular surfaces of the TMJ is useful to determine the strains undergone by the disc that if too high might compromise its integrity. The development of our research in TMJ mechanics has evolved from the acquisition of the traces of single mandibular points to an accurate and compact description of mandibular motion, in which the mechanical advantage of jaw muscles, and forces and torques acting on the jaw are considered as well. The combination of three-dimensional software models of TMJ anatomies obtained from MRI and jaw tracking with six degrees of freedom permits a subject-specific dynamic analysis of the intra-articular space, providing insight into individual disc deformation during function and TMJ loading. Studies performed with this system indicate that both TMJs are loaded during chewing, the balancing more so than the working joint. In fact, during chewing, the intra-articular distance is smaller for hard than for soft food, on closing than on opening, on the balancing than on the working side. This last finding is confirmed by static biting experiments, in which the condyle-fossa distance decreases more on the side contralateral to the bite force, depending on its magnitude. Also studies on the dynamics of compression areas indicate that plowing can occur through the disc during function, especially mediolaterally, due to stress field translation. This effect might contribute to cartilage wear and fatigue also because the disc is weaker mediolaterally. Further data indicate that the lateral area of the disc is mostly exposed to a higher mechanical energy density. This will be more intensively investigated using finite element method.
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PMID:Modeling of temporomandibular joint function using MRI and jaw-tracking technologies--mechanics. 1608 34

Health-related quality of life (HRQoL) has been more intensively studied in multiple sclerosis (MS) than in any other neurological disorder. Traditional medical models of impairment and disability are an incomplete summary of disease burden. Quality of life can be thought of as the sum of all sources of satisfaction (including anticipated sources) minus all threats (including anticipated threats). Many psychosocial factors-including coping, mood, self-efficacy, and perceived support-influence the quality of life of patients with MS more than biological variables such as weakness or extent of MRI lesions. Neuropsychiatric complications such as cognitive impairment and fatigue are also important predictors, even in those patients in the early stages of the disease. We review generic and specific HRQoL measures to help clinicians choose the most appropriate therapies. Subjective (self-report) HRQoL measures may serve to alert clinicians to areas that would otherwise be overlooked. Studies of new interventions should include an assessment of HRQoL not just impairment or disability alone.
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PMID:Quality of life and its assessment in multiple sclerosis: integrating physical and psychological components of wellbeing. 1610 62

Muscle fatigue has been known to differentially affect the activation level of the primary motor cortices (MIs) of the brain's two hemispheres. Whether this fatigue-related decoupling influence on the motor cortical signals extends beyond the motor action to the after-fatigue-task resting state is unknown. This question can be addressed by analyzing functional connectivity (FC) of low-frequency oscillations of resting-state functional MRI (fMRI) signals of the MIs. Low-frequency oscillations (<0.08 Hz) have been detected in many fMRI studies and appear to be synchronized between functionally related areas. These patterns of FC have been shown to differ between normal and various pathological states. The purpose of this study was to examine muscle fatigue-induced resting-state interhemispheric motor cortex FC changes in healthy subjects. We hypothesized that muscle fatigue would create a temporary "disrupted state" in the brain, and would decrease resting state interhemispheric motor cortical FC. Ten healthy subjects performed repetitive unilateral handgrip contractions that induced significant muscle fatigue, with resting state fMRI data collected before and after the task. After excluding two subjects due to gross head motion, interhemispheric motor cortex FC was assessed by cross-correlating the MI fMRI signal time courses. We found that the number of significant interhemispheric correlations in the MI fMRI signals decreased significantly after the performance of the fatigue task. These results suggest that resting state interhemispheric motor cortex FC may be used as an index of recovery from fatigue.
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PMID:Reductions in interhemispheric motor cortex functional connectivity after muscle fatigue. 1614 Feb 87

The purpose of this study was to describe the anatomical distribution and incidence of fatigue injuries of the femur in physically-active young adults, based upon MRI studies. During a period of 70 months, 1857 patients with exercise-induced pain in the femur underwent MRI of the pelvis, hips, femora, and/or knees. Of these, 170 patients had a total of 185 fatigue injuries, giving an incidence of 199 per 100 000 person-years. Bilateral injuries occurred in 9% of patients. The three most common sites affected were the femoral neck (50%), the condylar area (24%) and the proximal shaft (18%). A fatigue reaction was seen in 57%, and a fracture line in 22%. There was a statistical correlation between the severity of the fatigue injury and the duration of pain (p = 0.001). The location of the pain was normally at the site of the fatigue injury. Fatigue injuries of the femur appear to be relatively common in physically-active patients.
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PMID:Fatigue injuries of the femur. 1618 13

This study assessed low back and trapezius muscle activity in bus drivers, with or without recurrent low back pain (LBP), during the long term driving. In addition, low back and neck-shoulder pain intensities and fatigue were measured and the effect of low back support was observed. Also the possible source of LBP was attempted to assess by vibration pain provocation test and lumbar MRI. Forty bus drivers (recurrent LBP n = 25) participated in this study. Low back and neck-shoulder pain and subjective fatigue intensity was assessed by visual analogue scales (VAS) before and after driving. Lumbar paraspinal and trapezius muscle activation during driving was measured by surface EMG. Vibration pain provocation test was applied for all subjects. Average paraspinal myoelectric activity during driving was approximately 1% of MVC in both groups. Average trapezius myoelectric activity during driving was from 2 to 4% of MVC. Trapezius muscle activity was higher in back healthy drivers than in those with LBP. The low back support had no effect either on paraspinal or trapezius EMG activity. Low back and neck-shoulder fatigue increased during driving in both groups especially in those subjects with positive vibration pain provocation. The neck-shoulder pain and fatigue were more severe in drivers suffering from LBP. Low back support had no effect on low back and neck-shoulder subjective fatigue and neck-shoulder pain but tended to limit the LBP increase during driving. Paraspinal muscle loading in urban bus drivers was very limited and either LBP or ergonomic low back support had no effect on it. Trapezius muscle seemed to be less active in drivers suffering from recurrent LBP. Internal disc disruptions may expose to pain and fatigability during driving.
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PMID:Back and neck extensor loading and back pain provocation in urban bus drivers with and without low back pain. 1622 76

We present the fourth case of a primary pancreatic anaplastic large cell lymphoma (ALCL), ALK-. An 80-year-old man was admitted to our clinic for further investigation of a fever of unknown origin. He noted anorexia, weight loss and fatigue. His laboratory tests showed anemia and a great elevation of ESR, LDH, and beta (2) microglobulin. In CT and MRI scan, a soft tissue mass in the pancreas was observed. A repeated endoscopy after his admission revealed an ulcerated mass-like deformity of the duodenal bulb. Explorative laparotomy confirmed a diffuse spread of an unresectable malignant pancreatic mass extending to the adjacent organs. Duodenal and surgical biopsies identified an ALCL of T-cell lineage, ALK-. The patient died in the Intensive Care Unit due to hemodynamic instability. Our case is the first one indicating that primary pancreatic lymphoma should be suspected in a patient with pancreatic mass and elevated serum LDH and beta(2) microglobulin.
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PMID:Primary pancreatic anaplastic large cell lymphoma, ALK negative: a case report. 1627 56


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