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

We evaluated whether concurrent radiotherapy (RT) affected delivery and toxicity of adjuvant intravenous CMF (cyclophosphamide, methotrexate and 5-fluorouracil) in women with operable breast cancer. The medical charts of 321 consecutive breast cancer patients who received CMF either alone for 6 cycles, or for 4 cycles following of an anthracycline (A-CMF) were reviewed. One hundred forty-four women underwent radiotherapy concurrently with CMF. Optimal CMF delivery (success as opposite to failure) was defined as the combined achievement of an average relative dose intensity (aRDI) > or = 85% and an average percent of the total dose (aPTD) > or = 90% for the three drugs in the CMF regimen. Multivariate logistic regression analysis showed that concurrent-RT did not affect CMF delivery (OR for success 1.391 p=0.230). The sequential A-CMF regimen (OR for success 0.208, 95% C.I. 0.120-0.360, p<0.001) and age > or = 56 (OR for success 0.351, 95% C.I. 0.200-0.161, p<0.001) were independently associated with suboptimal CMF delivery. Moreover, concurrent RT was independently associated with increased leukopenia, thrombocytopenia, upper abdominal pain, mucositis and fatigue. Our retrospective analysis suggests that concurrent-RT has no impact on optimal CMF delivery, but it increases the burden of CMF-related toxicity.
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PMID:Concurrent radiotherapy does not affect adjuvant CMF delivery but is associated with increased toxicity in women with early breast cancer. 1657 99

Neuromuscular performance capabilities, including those measured by evoked responses, may be adversely affected by fatigue; however, the capability of the neuromuscular system to initiate muscle force rapidly under these circumstances is yet to be established. Sex-differences in the acute responses of neuromuscular performance to exercise stress may be linked to evidence that females are much more vulnerable to anterior cruciate ligament injury than males. Optimal functioning of the knee flexors is paramount to the dynamic stabilisation of the knee joint, therefore the aim of this investigation was to examine the effects of acute maximal intensity fatiguing exercise on the voluntary and magnetically-evoked electromechanical delay in the knee flexors of males and females. Knee flexor volitional and magnetically-evoked neuromuscular performance was assessed in seven male and nine females prior to and immediately after: (1) an intervention condition comprising a fatigue trial of 30-s maximal static exercise of the knee flexors, (2) a control condition consisting of no exercise. The results showed that the fatigue intervention was associated with a substantive reduction in volitional peak force that was greater in males compared to females (15.0, 10.2%, respectively, P < 0.01) and impairment to volitional electromechanical delay in females exclusively (19.3%, P < 0.05). Similar improvements in magnetically-evoked electromechanical delay in males and females following fatigue (21%, P < 0.001), however, may suggest a vital facilitatory mechanism to overcome the effects of impaired voluntary capabilities, and a faster neuromuscular response that can be deployed during critical times to protect the joint system.
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PMID:Effects of acute fatigue on the volitional and magnetically-evoked electromechanical delay of the knee flexors in males and females. 1746 81

Tickborne relapsing fever (TBRF) is a bacterial illness caused by certain species of Borrelia and transmitted through brief and painless bites from Ornithodoros ticks. Illness usually is characterized by intermittent periods of fever, fatigue, and muscle aches. In April 2005, CDC received reports of two cases of severe TBRF associated with acute respiratory distress syndrome (ARDS) in residents of California and Nevada. After a report describing these cases was posted on CDC's Epidemic Information Exchange (Epi-X), health officials in Washington reported a third severe case associated with ARDS. This report summarizes these three cases and the results of the subsequent epidemiologic investigations. The findings indicate that ARDS might occur more frequently in patients with TBRF than previously recognized. Optimal management of TBRF requires both prompt diagnosis and careful observation during the initial phases of treatment.
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PMID:Acute respiratory distress syndrome in persons with tickborne relapsing fever--three states, 2004-2005. 1794 65

Fatigue, pain, distress, and anorexia are four commonly encountered symptoms in cancer. To evaluate the usefulness of a single-item screening for these symptoms, 597 ambulatory outpatients with solid tumors were administered a self-report screening instrument within the first 12 weeks of chemotherapy. Patients rated the severity of each symptom on a 0-10 scale, at its worst over the past three days, with higher ratings associated with higher symptom levels. From this sample, 148 patients also completed a more comprehensive assessment of these symptoms. Two criteria were used to determine optimal cut-off scores on the screening items: 1) the sensitivity and specificity of each screening item to predict clinical cases using receiver-operating characteristics analysis and 2) the proportion of patients at each screening score who reported that some relief of the target symptom would significantly improve their life. Optimal cut-off scores ranged from 4 to 6 depending on the target symptom (area under the curve range=0.68-0.88). Use of single-item screening instruments for fatigue, pain, distress, and anorexia may assist routine clinical assessment in ambulatory oncology practice. In turn, such assessments may improve identification of those at risk of morbidity and decreased quality of life due to excess symptom burden.
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PMID:Use of a single-item screening tool to detect clinically significant fatigue, pain, distress, and anorexia in ambulatory cancer practice. 1795 45

The NEAT trial reported considerable benefit for ECMF (epirubicin followed by cyclophosphamide, methotrexate and 5-fluorouracil) of 28% for relapse-free survival (RFS) and 30% for overall survival (OS), when compared with classical CMF in early breast cancer. To assess tolerability, toxicity, dose intensity and quality of life (QoL) analyses were undertaken. All 2021 eligible patients had common toxicity criteria (CTC), delivered chemotherapy and supportive treatments details and long-term morbidities recorded. The QoL substudy used multiple validated measures. ECMF produced low CTC scores, although higher than CMF for nausea, vomiting, alopecia, constipation, stomatitis (P<0.001), infection (P=0.001) and fatigue (P=0.03). Supportive treatments required, however, were similar across randomised treatments. On-treatment deaths were more common with CMF (13) than ECMF(5). Optimal course-delivered dose intensity (CDDI > or =85%) was received more often by ECMF patients (83 vs 76%: P=0.0002), and was associated with better RFS (P=0.0006). QoL over 2 years was equivalent across treatments, despite minimally worse side effects for ECMF during treatment. ECMF benefit spanned all levels of toxicity, CDDI and QoL. There are no reported acute myeloid leukaemias or cardiac dysfunctions. ECMF is tolerable, deliverable, and significantly more effective than CMF, with no serious long-term toxicity or QoL detriment.
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PMID:NEAT: National Epirubicin Adjuvant Trial--toxicity, delivered dose intensity and quality of life. 1879 68

We propose that the critical function of sleep is to prevent uncontrolled neuronal feedback while allowing rapid responses and prolonged retention of short-term memories. Through learning, the brain is tuned to react optimally to environmental challenges. Optimal behavior often requires rapid responses and the prolonged retention of short-term memories. At a neuronal level, these correspond to recurrent activity in local networks. Unfortunately, when a network exhibits recurrent activity, small changes in the parameters or conditions can lead to runaway oscillations. Thus, the very changes that improve the processing performance of the network can put it at risk of runaway oscillation. To prevent this, stimulus-dependent network changes should be permitted only when there is a margin of safety around the current network parameters. We propose that the essential role of sleep is to establish this margin by exposing the network to a variety of inputs, monitoring for erratic behavior, and adjusting the parameters. When sleep is not possible, an emergency mechanism must come into play, preventing runaway behavior at the expense of processing efficiency. This is tiredness.
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PMID:A new hypothesis for sleep: tuning for criticality. 1919 2

Although the full physiological significance of vasomotion is still debated, it is generally thought to have a role in optimizing tissue oxygenation parameters. We study the effect of vasomotion rhythm in skeletal muscle on oxygen transport using a computational model. The model is used: (i) to test a novel hypothesis that "vasomotors" form a chemical network in which the rhythm adapts to meet oxygen demand in skeletal muscle and (ii) to study the contribution of desynchronized/chaotic vasomotion in optimizing oxygen delivery to skeletal muscle. We formulate a 2D grid model of skeletal muscle consisting of an interleaved arrangement of vessels and muscle fibers fired by a motor neuronal network. The vasomotors too form a network interacting by chemical means. When positive (negative) synapses dominate, the neuronal network exhibits synchronized (desynchronized) activity. Similarly, when positive (negative) chemical interactions dominate, the vessels exhibit synchronized (desynchronized) activity. Optimal oxygenation is observed when both neuronal network and vasomotor network exhibit desynchronous activity. Muscle oxygenation is thought to result by interactions between the fiber/neuron network and the vessel network; optimal oxygenation depends on precise rhythm-related conditions on the two networks. The model provides interesting insights into the phenomenon of muscle fatigue.
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PMID:Desynchronized vasomotion and desynchronized fiber activation pattern enhance oxygenation in a model of skeletal muscle. 1930 86

Adequacy of hemodialysis is frequently equated with Kt/V(urea) , the amount of urea clearance (K) multiplied by time (t) and divided by urea distribution volume (V). Several formulas have been developed to calculate Kt/V(urea) from the pre- and post-dialysis urea concentrations. In three-times-weekly hemodialysis, a single pool (spKt/V(urea)) value of 1.3 per treatment is commonly considered to indicate adequate therapy. Despite providing the recommended spKt/V(urea) of 1.3 per treatment, short dialysis with rapid ultrafiltration is associated with multiple intradialytic and interdialytic complications. Patients experience cramps, nausea, vomiting, headaches, fatigue, hypotensive episodes during dialysis, and hangover after dialysis; patients remain fluid overloaded with subsequent poor blood pressure control, left ventricular hypertrophy, diastolic dysfunction, and high cardiovascular mortality. According to Webster's dictionary, "optimal" means most desirable or satisfactory; "adequate" means sufficient for a specific requirement or barely sufficient or satisfactory. Optimal dialysis is the method of dialysis yielding results that cannot be further improved. New approaches, including hemeral quotidian or long nocturnal dialysis, provide opportunities to abandon the notion that adequate dialysis is "good enough" for our patients. Optimal dialysis should be our goal. Dialysis sessions should be long and frequent enough to provide excellent intra- and interdialytic tolerance of hemodialysis, normalization of serum calcium and phosphorus, blood pressure control, normal myocardial morphology and function, and hormonal balance, and to eliminate all, even subtle, uremic symptoms.
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PMID:We should strive for optimal hemodialysis: a criticism of the hemodialysis adequacy concept. 1937 36

Recent advances in neurobiology have aided our understanding of attention-deficit hyperactivity disorder (ADHD). The higher-order association cortices in the temporal and parietal lobes and prefrontal cortex (PFC) interconnect to mediate aspects of attention. The parietal association cortices are important for orienting attentional resources in time/space, while the temporal association cortices analyse visual features critical for identifying objects/places. These posterior cortices are engaged by the salience of a stimulus (its physical characteristics such as movement and colour). Conversely, the PFC is critical for regulating attention based on relevance (i.e. its meaning). The PFC is important for screening distractions, sustaining attention and shifting/dividing attention in a task-appropriate manner. The PFC is critical for regulating behaviour/emotion, especially for inhibiting inappropriate emotions, impulses and habits. The PFC is needed for allocating/planning to achieve goals and organizing behaviour/thought. These regulatory abilities are often referred to as executive functions. In humans, the right hemisphere of the PFC is important for regulating distractions, inappropriate behaviour and emotional responses. Imaging studies of patients with ADHD indicate that these regions are underactive with weakened connections to other parts of the brain. The PFC regulates attention and behaviour through networks of interconnected pyramidal cells. These networks excite each other to store goals/rules to guide actions and are highly dependent on their neurochemical environment, as small changes in the catecholamines noradrenaline (NA) or dopamine (DA) can have marked effects on PFC function. NA and DA are released in the PFC according to our arousal state; too little (during fatigue or boredom) or too much (during stress) impairs PFC function. Optimal amounts are released when we are alert/interested. The beneficial effects of NA occur at postsynaptic alpha(2A)-receptors on the dendritic spines of PFC pyramidal cells. Stimulation of these receptors initiates a series of chemical events inside the cell. These chemical signals lead to the closing of special ion channels, thus strengthening the connectivity of network inputs to the cell. Conversely, the beneficial effects of moderate amounts of DA occur at D(1) receptors, which act by weakening irrelevant inputs to the cells on another set of spines. Genetic linkage studies of ADHD suggest that these catecholamine pathways may be altered in some families with ADHD, e.g. alterations in the enzyme that synthesizes NA (DA beta-hydroxylase) are associated with weakened PFC abilities. Pharmacological studies in animals indicate catecholamine actions in the PFC are highly relevant to ADHD. Blocking NA alpha(2A)-receptors in the PFC with yohimbine produces a profile similar to ADHD: locomotor hyperactivity, impulsivity and poor working memory. Conversely, drugs that enhance alpha(2)-receptor stimulation improve PFC function. Guanfacine directly stimulates postsynaptic alpha(2A)-receptors in the PFC and improves functioning, while methylphenidate and atomoxetine increase endogenous NA and DA levels and indirectly improve PFC function via alpha(2A)- and D(1) receptor actions. Methylphenidate and atomoxetine have more potent actions in the PFC than in subcortical structures, which may explain why proper administration of stimulant medications does not lead to abuse. Further understanding of the neurobiology of attention and impulse control will allow us to better tailor treatments for specific patient needs.
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PMID:Toward a new understanding of attention-deficit hyperactivity disorder pathophysiology: an important role for prefrontal cortex dysfunction. 1962 76

The ability of galantamine hydrobromide (GAL HBr) treatment to antagonize O-ethyl-S-(2-diisopropylaminoethyl) methylphosphonothiolate (VX)-induced lethality, impairment of muscle tension, and electroencephalographic (EEG) changes was assessed in guinea pigs. Guinea pigs were challenged with 16.8 microg/kg VX (2LD50). One min after challenge, animals were administered 0.5 mg/kg atropine sulfate (ATR) and 25 mg/kg pyridine-2-aldoxime methochloride (2-PAM). In addition, guinea pigs were given 0, 1, 2, 4, 8 or 10 mg/kg GAL as a post-exposure treatment immediately prior to ATR and 2-PAM. Animals were either monitored for 24-h survival, scheduled for electroencephalography (EEG) recording, or euthanized 60 min later for measurement of indirectly-elicited muscle tension in the hemidiaphragm. Post-exposure GAL therapy produced a dose-dependent increase in survival from lethal VX challenge. Optimal clinical benefits were observed in the presence of 10 mg/kg GAL, which led to 100% survival of VX-challenged guinea pigs. Based on muscle physiology studies, GAL post-exposure treatment protected the guinea pig diaphragm, the major effector muscle of respiration, from fatigue, tetanic fade, and muscular paralysis. Protection against the paralyzing effects of VX was dose-dependent. In EEG studies, GAL did not alter seizure onset for all doses tested. At the highest dose tested (10 mg/kg), GAL decreased seizure duration when administered as a post-exposure treatment 1 min after VX. GAL also reduced the high correlation associated between seizure activity and lethality after 2LD50 VX challenge. GAL may have additional benefits both centrally and peripherally that are unrelated to its established mechanism as a reversible acetylcholinesterase inhibitor (AChEI).
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PMID:Galantamine is a novel post-exposure therapeutic against lethal VX challenge. 1964 7


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