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

Implantable electrical conductor wires and coils of MP35N and drawn MP35N tube filled with a silver core (DFT) were tested in rotary bending to evaluate fatigue characteristics and failure mechanisms. Detailed stress analysis enabled evaluation of helical coil fatigue in bending with respect to theoretical stress. The relations between the maximum cyclic stress (S) and the cycles to failure (N) were obtained by introducing cyclic stresses on over 600 samples. Microscopic evaluation using scanning electron microscopy was performed to identify failure mechanisms. The results show that the stress analysis presented is a viable means for assessing the stress state in a composite coil structure in rotary loop testing, comparable S-N fatigue data sets for MP35N and DFT conductors are not consistently significantly different, S-N relationships for coils and wires of the MP35N and DFT appear to lie on the same curves, and failures of all sample types initiate on the outside surface of the wire. Differences in crack propagation and final fracture are shown as a function of sample type and cyclic stress.
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PMID:Rotary bending fatigue of coils and wires used in cardiac lead design. 950 41

Pulmonary mycotoxicosis (PM), also termed organic dust toxic syndrome or silo unloader's syndrome, is an acute illness resulting from massive inhalation of microbial toxins in organic dusts. It has not been well described histologically. Three cases of PM are presented in this report. Open lung biopsies were examined in each case. All of the patients were farmers with no prior lung disease. One had burning in his eyes, throat, and chest after exposure to moldy silage; chills, fever, dry cough, malaise, and weakness developed within 24 hours. Two patients presented with fever, progressive dyspnea, cough, and fatigue within 24 hours of emptying a corncrib, cleaning a chicken coop, and baling hay. Bilateral alveolar and interstitial infiltrates on chest roentgenograms and leukocytosis with neutrophilia were observed in all of the three patients. Two patients became hypoxemic and required mechanical ventilation. Histologic examination showed acute and organizing diffuse alveolar damage in two biopsy specimens and an acute bronchopneumonia in the third. One specimen had 1- to 10-microm ovoid organisms demonstrable with methenamine silver stains; cultures grew Fusarium and Penicillium species. The other two biopsy specimens had negative tissue cultures and special stains for organisms, although Penicillium species were grown from a preoperative bronchoalveolar lavage in one case. The two patients on mechanical ventilation recovered completely with high-dose steroids. The third patient recovered without steroids. No patient had residual functional deficits or chest radiographic abnormalities. PM can be distinguished from allergic and infectious diseases common in individuals exposed to large amounts of organic dust by its clinicopathologic features.
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PMID:Pulmonary mycotoxicosis: a clinicopathologic study of three cases. 961 95

Low-frequency fatigue was investigated in nine female and one male adult pigtail monkeys (Macaca nemestrina) with a mean weight of 5.3 kg (range 4.3 to 6.5 kg). After sedation and anesthesia, silver electrodes were inserted into the anterior and posterior parts of the right masseter muscle. The contralateral muscle was used as a control. The masseter muscles were stimulated for 3 minutes (4 Hz, 2 ms, 100 V). After a 5-minute rest period, the stimulation was repeated with the same duration and voltage but at a higher frequency of 8 Hz. Bite forces were measured, and muscle biopsies were obtained from the central part of the right masseter and immediately frozen in liquid nitrogen. After freeze-drying, a fluorometric analysis that used enzymatic methods for measuring levels of glycogen, glucose, lactate, pyruvate, creatine phosphate, nicotinamide-adenine dinucleotide (NAD), and reduced NAD (NADH) was performed. The bite force decreased by 12% after the initial 3 minutes of work. After the second contraction the bite force decreased to 56%. Prominent substrate depletion was observed. The precontraction levels of glycogen, glucose, and phosphocreatine were all reduced. The NADH and the NAD concentrations increased. An accumulation of metabolites was evident. The pyruvate increased by 32% and lactate levels increased by a factor of 3. The male measurements were comparable to the nine female measures for each assessment. The substantial substrate depletion in combination with a prominent accumulation of metabolites may contribute to the development of low-frequency fatigue.
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PMID:Frequency-dependent fatigue development during electrical stimulation in the masseter muscle of pigtail monkeys. 1042 74

This pilot study concerned the cyclic fatigue of five different endodontic post systems (AccessPost(R), Flexi-Flange(R), Flexi-Post(R), ParaPost(R), and Vlock(R)) with four different core materials (Tytin(R) Silver amalgam, Ti-Core(R), Ketac-Silver(R) and G-C Miracle Mix(R)). In vitro cyclic fatigue was performed using a fatigue machine that simulates masticatory fatigue forces. An instantaneous force of 5 lb was applied to each post and core combination for a test configuration of 4 000 000 repetitions or until failure occurred. The type of failure and number of repetitions at failure was recorded for each sample tested. Two-way ANOVA was used to compare groups. All posts/core samples with Ti-Core and Tytin Silver amalgam completed the test configuration of 4 000 000 cycles without failures. All posts/core samples with Ketac-Silver failed before the 4 000 000 test cycle configuration, all as a result of core failures. All posts/core samples with G-C Miracle Mix failed in a similar way. The Newman-Keuls multiple comparison test illustrated that Ti-Core and Tytin Silver amalgam were similar to each other and were superior to both G-C Miracle Mix and Ketac-Silver. Similar fatigue test results are found in the literature.
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PMID:Pilot study of the cyclic fatigue characteristics of five endodontic posts with four core materials. 1063 48

The relationships between exercise and metabolites as well as between exercise and sarcoplasmic reticulum function were studied in gastrocnemius muscle of ovariectomized-trained rats. Prolonged moderate-intensity exercise, treadmill up-hill run for 90 min with a 10 degree incline, decreased the muscle glycogen content. Exercise until exhaustion further lowered the glycogen concentration to 13% of the control, together with a significant decrease of ATP and glucose-6-phosphate concentrations. Also, Ag+-induced Ca2+ release, measured in whole muscle homogenate, showed a 30% reduction on exhaustion, while Ca2+ uptake was unaffected by this exercise. ATPase activities, of both homogenate and SR vesicles, and Ca2+ transport in the latter preparation were not altered on exhaustion. It could be concluded from these results that muscular fatigue in ovariectomized rats after aerobic exercise is caused by the change in energy supply and Ca2+ release from the SR, this latter possibly due to metabolites generated by the exercise.
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PMID:Effects of exercise on muscle metabolites and sarcoplasmic reticulum function in ovariectomized rats. 1223 16

Although it is well established that patients suffering from malaria experience skeletal muscle problems (contracture, aches, fatigue, weakness), detailed studies have not been performed to investigate changes in the contractile function and biochemical properties of intact and skinned skeletal muscles of mammals infected with malaria. To this end, we investigated such features in the extensor digitorium longus (EDL, fast-twitch, glyocolytic) and in the soleus (SOL, slow-twitch, oxidative) muscles from mice infected with Plasmodium berghei. We first studied maximal tetanic force (T(max)) produced by intact control and malaria-infected muscles before, during and after fatigue. Triton-skinned muscle fibres were isolated from these muscles and used to determine isometric contractile features as well as a basic biochemical profile as analysed by silver-enhanced SDS-PAGE. We found that the T(max) of intact muscles and the maximal Ca2+-activated force (F(max)) of Triton-skinned muscle fibres were reduced by approximately 50% in malarial muscles. In addition, the contractile proteins of Triton-skinned muscle fibres from malarial muscles were significantly less sensitive to Ca2+. Biochemical analysis revealed that there was a significant loss of essential contractile proteins (e.g. troponins and myosin) in Triton-skinned muscle fibres from malarial muscles as compared to controls. The biochemical alterations (i.e., reduction of essential contractile proteins) seem to explain well the functional modifications resolved in both intact muscles and Triton-skinned muscle fibres and may provide a suitable paradigm for the aetiology of muscle symptoms associated with malaria.
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PMID:Functional and biochemical modifications in skeletal muscles from malarial mice. 1572 39

Fifty-three chronic fatigue syndrome patients treated at a complementary medical centre were assessed over 12 months. Measures included the Chalder Fatigue scale, the General Health Questionnaire (GHQ) and positivity in illness (Silver Lining Questionnaire, SLQ). The SLQ measured at 6 and 9 months predicted (p < .01) mental (but not physical) fatigue at 12 months independently of current mental fatigue, initial mental fatigue, duration since diagnosis and time between start of treatment and entry to the study. The GHQ did not predict fatigue at any time point. The results suggest that a caring therapeutic intervention increases positive interpretations of illness prior to improvements in mental fatigue, but that positivity does not play a causal role in the reduction of fatigue.
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PMID:Chronic fatigue syndrome: the role of positivity to illness in chronic fatigue syndrome patients. 1690 69

Obesity has been found to be associated with left ventricular (LV) hypertrophy (LVH). However, the occurrence of LVH in obese teenagers who are involved in sport programs has not been studied. The objective of this study was to evaluate the prevalence of LVH and its correlation with obesity, gender, and symptoms in teenage athletes. We used echocardiographic database of 1,500 adolescences between the ages of 12 and 20 years who were actively involved in school sport programs. We evaluated associations between obesity and LVH (defined as LV wall thickness (LVWT)) >12 mm, or LV mass (LVM) >215 g or relative wall thickness (RWT) >0.43) and physical symptoms. Using univariate and multivariate analysis, male gender was associated with increased LVWT (multivariate odds ratio (OR) 4.87, confidence interval (CI) 2.41-9.82). Obesity was associated with parameters of LVH using univariate and multivariate analysis. (LVM > 215 g) occurred in 10.32% of obese athletes vs. 0.2% (1/445) of controls, (OR 51.33, CI 6.05-433.8), P < 0.001, LVWT >12 mm occurred in 16.5% of obese students vs. 3.6% of controls (OR 5.2, CI 2.7-10.1, P < 0.001), RWT >0.43 occurred in 41.4% of obese students vs. 15.7% of controls (OR 3.78, CI 2.11-6.76, P < 0.001). After adjusting for age and gender, reported history of shortness of breath (SOB), fatigue and leg edema were also significantly more prevalent in obese students and in students with LVH. In conclusion obesity is associated with LVH in a population of healthy teenagers actively involved in sport programs. Furthermore, the presence of LVH was independently associated with many physical symptoms suggesting negative effect of LVH on myocardial function.
Obesity (Silver Spring) 2009 Mar
PMID:Left ventricular hypertrophy is associated with obesity, male gender, and symptoms in healthy adolescents. 1923 46

The aim of this study was to determine health-related quality of life and fatigue measures in obese subjects and to compare scores with age- and gender-matched population norms. A total of 163 obese subjects were recruited from laparoscopic-adjustable gastric banding or exercise and diet weight loss programs between March 2006 and December 2007. All subjects completed the Medical Outcomes Study Short Form 36 (SF-36), Assessment of Quality of Life (AQoL), and Multidimensional Assessment of Fatigue (MAF) questionnaires. One-sample t-tests were used to compare transformed scores with age- and gender-matched population norms and controls. Obese subjects have significantly lower SF-36 physical and emotional component scores, significantly lower AQoL utility scores and significantly higher fatigue scores compared to age-matched population norms. Within the study cohort, the SF-36 physical functioning, role physical and bodily pain scores, and AQoL utility index were even lower in subjects with clinical knee osteoarthritis (OA). However, obese individuals without OA still had significantly lower scores compared to population norms. Obesity is associated with impaired health-related quality of life and disability as measured by the SF-36, AQoL, and fatigue score (MAF) compared to matched population norms.
Obesity (Silver Spring) 2009 Nov
PMID:Influence of BMI on health-related quality of life: comparison between an obese adult cohort and age-matched population norms. 1939 May 22

Atypical antipsychotic medications like olanzapine (OLZ) induce weight gain and increase the risk of diabetes in patients with schizophrenia. The goal of this study was to assess potential mechanisms of OLZ-induced weight gain and accompanying metabolic effects. Healthy, lean, male volunteers received OLZ and placebo (PBO) in a randomized, double-blind, crossover study. In periods 1 and 2, subjects received OLZ (5 mg for 3 days then OLZ 10 mg for 12 days) or matching PBO separated by a minimum 12-day washout. Twenty-four hour food intake (FI), resting energy expenditure (REE), activity level, metabolic markers, and insulin sensitivity (IS) were assessed. In total, 30 subjects were enrolled and 21 completed both periods. Mean age and BMI were 27 years (range: 18-49 years) and 22.6 +/- 2.2 kg/m(2), respectively. Relative to PBO, OLZ resulted in a 2.62 vs. 0.08 kg increase in body weight (P < 0.001) and 18% (P = 0.052 or 345 kcal) increase in FI. Excluding one subject with nausea and dizziness on the day of OLZ FI measurement, the increase in FI was 547 kcal, (P < 0.05). OLZ increased REE relative to PBO (113 kcal/day, P = 0.003). Significant increases in triglycerides, plasminogen activator inhibitor-I (PAI-I), leptin, and tumor necrosis factor-alpha (TNF-alpha) were observed. No significant differences in activity level or IS were observed. This study provides evidence that OLZ pharmacology drives the early increase in weight through increased FI, without evidence of decreased energy expenditure (EE), activity level, or short-term perturbations in IS.
Obesity (Silver Spring) 2010 Aug
PMID:Increased food intake and energy expenditure following administration of olanzapine to healthy men. 2013 8


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