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

Road traffic crashes (RTCs) are responsible for a substantial fraction of morbidity and mortality and are responsible for more years of life lost than most of human diseases. In this review, we have tried to delineate behavioral factors that collectively represent the principal cause of three out of five RTCs and contribute to the causation of most of the remaining. Although sharp distinctions are not always possible, a classification of behavioral factors is both necessary and feasible. Thus, behavioral factors can be distinguished as (i) those that reduce capability on a long-term basis (inexperience, aging, disease and disability, alcoholism, drug abuse), (ii) those that reduce capability on a short-term basis (drowsiness, fatigue, acute alcohol intoxication, short term drug effects, binge eating, acute psychological stress, temporary distraction), (iii) those that promote risk taking behavior with long-term impact (overestimation of capabilities, macho attitude, habitual speeding, habitual disregard of traffic regulations, indecent driving behavior, non-use of seat belt or helmet, inappropriate sitting while driving, accident proneness) and (iv) those that promote risk taking behavior with short-term impact (moderate ethanol intake, psychotropic drugs, motor vehicle crime, suicidal behavior, compulsive acts). The classification aims to assist in the conceptualization of the problem that may also contribute to behavior modification-based efforts.
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PMID:Human factors in the causation of road traffic crashes. 1129 24

Because dental restorative materials undergo fatigue in use, testing is often performed in the laboratory to evaluate material responses to cyclic loading. The purpose of this study was to compare the lifetime predictions resulting from two methods of fatigue testing: dynamic and cyclic fatigue. Model composites were made in which one variable was the presence of a silanizing agent, and specimens tested in 4-point flexure. Cyclic fatigue was carried out at a frequency of 5 Hz, while dynamic fatigue testing spanned seven decades of stress rate application. Data were reduced and the crack propagation parameters for each material were calculated from both sets of fatigue data. These parameters were then used to calculate an equivalent static tensile stress for a 5-year survival time. The 5-year survival stresses predicted by dynamic fatigue data were approximately twice those predicted by cyclic fatigue data. In the absence of filler particle silanization, the survival stress was reduced by half. Aging in a water-ethanol solution reduced the survival stresses by a factor of four to five. Cyclic fatigue is a more conservative means of predicting lifetimes of resin-based composites.
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PMID:Lifetime predictions for resin-based composites using cyclic and dynamic fatigue. 1131 37

It was recently reported that MnSO4 stimulates glycogen synthase-dependent glucose transfer from UDPglucose into trichloroacetic acid precipitable endogenous glycoproteins (GSMn(T)) in human muscle extracts. To determine the physiologic significance of this reaction, we compared a new GS activity ratio, GSMn(T)/GSH(E) (where GSH(E) represents the usual glucose transfer to ethanol precipitable exogenous glycogen by GS at 7.2 mM glucose 6-phosphate), with the generally used GSL(E)/GSH(E) ratio (where GSL(E) represents glucose transfer at 0.17 mM glucose 6-P concentration). Biopsies were obtained from the quadriceps femoris muscle of healthy subjects at rest, after 40 min of bicycle exercise at approximately 65% of maximal oxygen uptake and after isometric contraction at 2/3 maximal force to fatigue (approximately 1 min). GSMn(T)/GSH(E) increased from 0.012+/-0.002 at rest to 0.054+/-0.008 (P<0.01) after 40 min of bicycle exercise and the increase in GSMn(T) activity was strongly related to the decrease in endogenous glycogen (i.e.. increase in short-chain endogenous glycoproteins) (r=0.90; P<0.05). On the other hand, GSL(E)/GSH(E) did not change significantly after bicycle exercise (rest = 0.49+/-0.04; exercise = 0.58+/-0.08, P>0.05). GSMn(T)/GSH(E) increased from 0.010+/-0.001 at rest to 0.016+/-0.002 (P<0.05) after isometric exercise, whereas GSL(E)/GSH(E) decreased from 0.27+/-0.04 to 0.20+/-0.02 (P<0.05) under corresponding conditions. Last, insulin, which stimulates glycogen synthesis, also increased GSMn(T)/GSH(E) (1.8-fold, P<0.05), as well as GSL(E)/GSH(E) (1.4-fold, P<0.05), in isolated rat soleus muscle. These data indicate that GSMn(T)/GSH(E) is influenced by endogenous substrate availability and covalent modification. Therefore, GSMn(T)/GSH(E) ratio may prove to be a useful alternative to other GS activity ratios that only reflect changes in the phosphorylation state of GS.
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PMID:A new glycogen synthase activity ratio in skeletal muscle: effects of exercise and insulin. 1148 2

The study aim was to investigate the relationship between alcohol consumption and health-related quality of life (HRQL) in post-therapeutic head and neck cancer patients. A cross-sectional study design was used with a sample of 191 subjects. Data were collected through interview and chart review. Alcohol consumption was evaluated through the dichotomous response to the question "During the past month have you drunk alcohol on one or more occasions?" HRQL was evaluated through the EORTC QLQ-C30 and H&N35 instruments. Data were also collected concerning sociodemographic and clinical variables. Multivariate regression was used to evaluate the hypothesized association. Of 28 domains comprising the EORTC QLQ-C30 and H&N35 instruments, eight were significantly associated with alcohol consumption, while 19 of the 20 remaining domains showed a tendency towards an association. Alcohol drinking was associated with significantly better physical and role functioning, and better global HRQL, plus less fatigue, pain, problems swallowing, dry mouth and feelings of illness. This suggests that, while the study findings are limited by its design and the sample bias, despite alcohol's role as an aetiological factor, it may be reasonable to drink a little as one recovers from head and neck cancer.
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PMID:Alcohol consumption is associated with improved health-related quality of life in head and neck cancer patients. 1175 25

Mutations in ion channels, or channelopathies, often lead to neurological disorders in which normal behavior is interrupted by attacks of debilitating symptoms such as pain, weakness or abnormal motor control. Attacks are often precipitated by similar stimuli, including stress, caffeine, ethanol, exercise or fatigue. The tottering mouse inherits a mutation in P/Q-type calcium channels and reliably exhibits attacks of abnormal movements, or dyskinesia. To determine if this mouse mutant is an appropriate model to study episodic neurological disorders, tottering mice were exposed to different environmental conditions or drugs known to precipitate attacks in humans. Stress, caffeine and ethanol all reliably induced attacks in tottering mice. Since calcium influx has previously been implicated in stress-induced tottering mouse attacks, the L-type calcium channel antagonist, nimodipine, and the NMDA receptor antagonist, MK 801, were tested for their ability to prevent attacks caused by caffeine or ethanol administration. Nimodipine blocked both caffeine- and ethanol-induced attacks, while MK 801 was effective against stress- and caffeine-induced attacks. These results support a common role for excess neuronal excitability and increased calcium influx in attacks triggered by diverse agents. Together, these results suggest that the tottering mouse is a novel model to investigate triggers of episodic neurological disorders.
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PMID:Triggers of paroxysmal dyskinesia in the calcium channel mouse mutant tottering. 1215 Oct 38

Previous studies that have quantified fatigue-related cognitive impairment as blood alcohol concentration (BAC) equivalents have been limited by two issues: the effect of practice on tests of cognition and, more importantly, the statistic used to quantify change in cognitive performance. The current study addressed these issues by adopting an ABACA design, which allowed for the adequate control of practice effects, and by using effect size metrics, which enabled direct comparisons to be made in performance impairments as a result of fatigue (i.e. sustained wakefulness of 24 h) and alcohol (i.e. BAC of 0.05%). Cognitive performance under the fatigue and alcohol conditions required the use of the CogState battery. It was demonstrated that fatigue caused greater impairment than alcohol on the speed of continuous attention and memory and learning, and on the accuracy of complex matching. Alcohol was more detrimental than fatigue only on the accuracy of memory and learning. Performances on the remaining tasks were the same for both the fatigue and alcohol conditions. These differences and similarities in performance impairment are discussed emphasizing the deleterious cognitive effects of relatively short periods of sustained wakefulness.
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PMID:Qualitative similarities in cognitive impairment associated with 24 h of sustained wakefulness and a blood alcohol concentration of 0.05%. 1463 37

To investigate the role played by muscle afferents in the sensorimotor loops, we measured the effects of capsaicin injection in newborns on the mechano- and metabosensitive discharges and the running performance at adulthood. Female Sprague Dawley rats received a subcutaneous injection of either 50 mg/kg capsaicin or solvent (10% ethanol, 10% Tween 80 in 0.9% saline) during their second day of life. These two groups were compared with a control, untreated group. Four months later, treadmill running performance and muscle afferent (mechanosensitive and metabosensitive) activities from the tibialis anterior muscle were measured. The capsaicin-treated group demonstrated a reduced maximal exercise capacity (time to exhaustion) and a reduced response of muscle metabosensitive fibers (group III and IV nerve endings) to the examined stimuli (arterial KCl and lactic acid injections, electrically induced fatigue) compared with the sham-injected solvent and control groups. Group IV afferent responses were absent in the compound nerve action potentials evoked by peripheral nerve stimulation. The response to mechanosensitive fibers to tendon vibration was also affected in the capsaicin group compared with the control and sham-injected groups, which presented a bimodal response corresponding to the activation of muscle spindles and Golgi tendon organs. Finally, measurements of the force developed by the tibialis anterior muscle from the beginning to the end of a 3-min muscle stimulation revealed a more significant fall in the capsaicin group compared with the others. The present experiments reveal that the pharmacological alteration of muscular metabosensitive afferent resulted in drastic changes in the neuromuscular sensory encoding and in the central neural network that could accelerate failure of the task during fatigue.
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PMID:Effects of neonatal capsaicin deafferentation on neuromuscular adjustments, performance, and afferent activities from adult tibialis anterior muscle during exercise. 1513 32

In the past century we have learned that driving performance is impaired by alcohol even in low dosage, and that many other drugs are also linked to impairment. This paper is a summary of some of the more relevant studies in the past fifty years--an overview of our knowledge and unanswered questions. There is no evidence of a threshold blood alcohol (BAC) below which impairment does not occur, and there is no defined category of drivers who will not be impaired by alcohol. Alcohol increases not only the probability of collision, but also the probability of poor clinical outcome for injuries sustained when impaired by alcohol. This review samples the results of the myriad studies that have been performed during the last half century as experiments have moved from examination of simple sensory, perceptual and motor behaviours to more complex measures of cognitive functioning such as divided attention and mental workload. These more sophisticated studies show that significant impairment occurs at very low BACs (< 0.02 gm/100 ml). However, much remains to be determined regarding the more emotional aspects of behaviour, such as judgment, aggression and risk taking. Considering that the majority of alcohol related accidents occur at night, there is a need for increased examination on the role of fatigue, circadian cycles and sleep loss. The study of the effects of drugs other than alcohol is more complex because of the number of substances of potential interest, the difficulties estimating drug levels and the complexity of the drug/subject interactions. The drugs of current concern are marijuana, the benzodiazepines, other psychoactive medications, the stimulants and the narcotics. No one test or group of tests currently meets the need for detecting and documenting impairment, either in the laboratory or at the roadside.
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PMID:Effects of alcohol and other drugs on driver performance. 1527 19

Acute respiratory failure is a common complication of drug abuse. It is more likely to develop in the setting of chronic lung disease or debility in those with limited respiratory reserve. Drugs may acutely precipitate respiratory failure by compromising respiratory pump function and/or by causing pulmonary pathology. Polysubstance overdoses are common, and clinicians should anticipate complications related to multiple drugs. Impairment of respiratory pump function may develop from central nervous system (CNS) depression (suppression of the medulla oblongata, stroke or seizures) or respiratory muscle fatigue (increased respiratory workload, metabolic acidosis). Drug-related respiratory pathology may result from parenchymal (aspiration-related events, pulmonary edema, hemorrhage, pneumothorax, infectious and non-infectious pneumonitides), airway (bronchospasm and hemorrhage), or pulmonary vascular insults (endovascular infections, hemorrhage, and vasoconstrictive events). Alcohol, cocaine, amphetamines, opiates, and benzodiazepines are the most commonly abused drugs that may induce events leading to acute respiratory failure. While decontamination and aggressive supportive measures are indicated, specific therapies to correct seizures, metabolic acidosis, pneumothorax, infections, bronchospasm, and agitation should be considered. Drug-related respiratory failure when due to CNS depression alone may portend well, but in patients with drug-related significant pulmonary pathology, a protracted course of illness may be anticipated.
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PMID:Acute respiratory failure from abused substances. 1529 19

More than two out of three of all fatal crashes in Maine occur on rural, two-lane collector or arterial roads. Head-on crashes on these roads account for less than 5% of the crashes, but they are responsible for almost half of all fatalities. Data analyzed in this study was provided by Maine Department of Transportation and covers all head-on crashes for 2000-2002 during which period there were 3,136 head-on crashes reported. Out of these, 127 were fatal crashes and 235 produced incapacitating but not fatal injuries. These two categories made up over 75% of the crash cost. A clear majority of head-on crashes on two-lane, rural roads in Maine were caused by drivers making errors or misjudging situations. Illegal/unsafe speed was a factor in 32% of the crashes while driver inattention/distraction was a primary factor in 28%. Fatigue was responsible for around one in 40 crashes and one in 12 fatal crashes. Alcohol or drugs was a factor in one in 12 crashes and one in nine fatal head-on crashes. Less than 8% of fatalities involved someone overtaking another vehicle, and only around 14% involved a driver intentionally crossing the centerline. Two in three fatal head-on crashes occurred on straight segments and 67% of these happened on dry pavement. There is a clear trend towards higher speed limits leading to a higher percentage of crashes becoming fatal or having incapacitating injuries. There is also a clear trend - if one keeps speeds constant and AADT within a certain range - that wider shoulders give higher crash severities. Also, for higher-speed roads, more travel lanes (than two) increase crash severity. In summary, there seems to be two major reasons why people get across the centerline and have head-on collisions: (a) people are going too fast for the roadway conditions; or (b) people are inattentive and get across the centerline more or less without noticing it. The latter category of crashes could probably be reduced if centerline rumble-strips were installed. More or less all head-on collisions could be eliminated if median barriers were installed. In-vehicle technology could also be used to significantly reduce the incidence of lane departures. Furthermore, today's speed limits should be better enforced since a high percentage of serious crashes involve illegal speeding. This should be combined with lowered speed limits for targeted high-crash segments.
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PMID:Segment characteristics and severity of head-on crashes on two-lane rural highways in Maine. 1642 19


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