Analysis of the tonic vibration reflex: influence of vibration variables on motor unit synchronization and fatigue

The influence of vibration frequency (40, 80, 100, 120, 150, or 200 Hz) at selected displacement amplitudes (0.2, 0.3 mm) on tonic vibration reflex (TVR) characteristics was investigated. The degree of synchronization of motor unit activity with vibratory stimuli in ten humans was determined using the electromyographic (EMG) activity of the finger and wrist flexor muscles when vibration was applied to the distal tendons of the hand flexor muscles. The EMG spectral analysis indicates that harmonic and subharmonic motor unit synchronization mechanisms contribute to the modulation of the amplitude of the TVR as the vibration frequency increases. Harmonic synchronization decreases while subharmonic synchronization increases as vibration frequency increases. It is suggested that the synchronization process influences muscle fatigue, since it forces the driving of motor units, leading to a decrease in contraction efficiency. This phenomenon most probably results from an impairment of excitation-contraction coupling. High-frequency vibration (>150 Hz) tends to induce less motor unit synchronization in a frequency range beyond the known mechanical resonance of biological tissues. The findings of this study may be applied to the design of hand-held power tools, since their vibration triggers the TVR in active muscles.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42240/1/421-75-6-504_70750504.pd

Impacts of gender, weather, and workplace differences in farm worker's gear

Background: The farmers cannot help working in outdoor conditions which have high humidity and solar radiation during the harvest period. Wearable items including clothing are the nearest environment of human body, and to understand the current state of them can be a way to set up an active prevention strategy against the health risk from heat stress in summertime agriculture. The aim of this study was to investigate the work wear and accessories which the elderly farmers used during agricultural working. Methods: One hundred twenty farmers (49 males and 71 females) working in nine separate sites on different days took part in this study. The average age of subjects was 61 years old. We examined the types of working posture, clothing, and items that the farmers used and/or wore. We also interviewed the farmers to know why they used such items while working. Results: The results of this study were as follows: (1) Farmers worked in the thermal environment which was over wet bulb globe temperature (WBGT) reference value, and the farmers could suffer heat stress due to workload induced from wearing conventional long-sleeved shirts and long trousers which were 0.66 clo in average under this summertime working thermal condition. (2) The farmers tended to change the layer of upper clothing for adapting to weather condition. (3) The types of footwear used seemed to be related with facilities as well as weather, and farmers tended to wear lighter footwear when the weather is hotter or when they work in PVC greenhouse. The majority of elderly farmers wore loafers and rubber shoes which had indistinguishable thin soles. (4) The types of hats showed the difference between facilities as well as gender and only 31.7 % of all participants used long brims. (5) Korean elderly farmers did not use any active cooling item as agricultural auxiliary tools in summer harvesting time. Conclusions: Korean elderly farmers worked in poor surroundings which could threaten their health and safety and seemed not to adjust their workload and clothing during summer harvest season. Thus, it would be necessary to monitor individual responses in order to ensure that the risk of heat stress is preventedopen

Incidentally Detected Situs Ambiguous in Adults

Situs ambiguous is rare congenital anomaly in adults. In 2 adult patients who admitted for different cardiac problems, situs ambiguous with polysplenia was detected. A 42-year-old male admitted for radio frequent catheter ablation of atrial fibrillation, and he had left-sided inferior vena cava (IVC), hepatic segment of IVC interruption with hemiazygos continuation, multiple spleens and intestinal malrotation. And in a 52-year-old female case who was hospitalized due to infective endocarditis after implanting pacemaker for sick sinus syndrome, multiple spleens, left-sided stomach, bilateral liver with midline gallbladder, and left-sided IVC were found. Those findings were consistent with situs ambiguous with polysplenia, but their features were distinctive

The Chemical Compositions of Very Metal-Poor Stars HD 122563 and HD 140283; A View From the Infrared

From high resolution (R = 45,000), high signal-to-noise (S/N > 400) spectra gathered with the Immersion Grating Infrared Spectrograph (IGRINS) in the H and K photometric bands, we have derived elemental abundances of two bright, well-known metal-poor halo stars: the red giant HD 122563 and the subgiant HD 140283. Since these stars have metallicities approaching [Fe/H] = -3, their absorption features are generally very weak. Neutral-species lines of Mg, Si, S and Ca are detectable, as well as those of the light odd-Z elements Na and Al. The derived IR-based abundances agree with those obtained from optical-wavelength spectra. For Mg and Si the abundances from the infrared transitions are improvements to those derived from shorter wavelength data. Many useful OH and CO lines can be detected in the IGRINS HD 122563 spectrum, from which derived O and C abundances are consistent to those obtained from the traditional [O I] and CH features. IGRINS high resolutions H- and K-band spectroscopy offers promising ways to determine more reliable abundances for additional metal-poor stars whose optical features are either not detectable, or too weak, or are based on lines with analytical difficulties.Comment: Accepted for publication in ApJ (28 pages, 4 tables, 6 figures

Dysregulation of adipose glutathione peroxidase 3 in obesity contributes to local and systemic oxidative stress

Glutathione peroxidase 3 (GPx3) accounts for the major antioxidant activity in the plasma. Here, we demonstrate that down-regulation of GPx3 in the plasma of obese subjects is associated with adipose GPx3 dysregulation, resulting from the increase of inflammatory signals and oxidative stress. Although GPx3 was abundantly expressed in kidney, lung, and adipose tissue, we observed that GPx3 expression was reduced selectively in the adipose tissue of several obese animal models as decreasing plasma GPx3 level. Adipose GPx3 expression was greatly suppressed by prooxidative conditions such as high levels of TNFalpha and hypoxia. In contrast, the antioxidant N-acetyl cysteine and the antidiabetic drug rosiglitazone increased adipose GPx3 expression in obese and diabetic db/db mice. Moreover, GPx3 overexpression in adipocytes improved high glucose-induced insulin resistance and attenuated inflammatory gene expression whereas GPx3 neutralization in adipocytes promoted expression of proinflammatory genes. Taken together, these data suggest that suppression of GPx3 expression in the adipose tissue of obese subjects might constitute a vicious cycle to expand local reactive oxygen species accumulation in adipose tissue potentially into systemic oxidative stress and obesity-related metabolic complications

Herb Mixture Inhibits Proinflammatory Mediators Through the Suppression of JNK and P38 Activation in LPS-Stimulated Raw 264.7 Macrophages

ABSTRACT Inflammation has been implicated as a pathophysiological feature underlying many chronic diseases. In the present study, we investigated the anti-inflammatory effect of new formulation of herb medicine, DG1102, composed by five different herbal ingredients such as Taraxaci Herba, Rhei Rhizoma, Houttuynia cordata Thunb. Houttuyniae Herba, Eriobotryae Folium which has been used for inflammatory diseases, in LPS-stimulated Raw 264.7 macrophages. DG1102 suppressed nitric oxide (NO), tumor necrosis factor-α (TNF-α), interleukin (IL)-1α, IL-6, IL-10 and macrophage inflammatory protein production in the lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages, as well as inducible nitric oxide synthase and cyclooxygenase 2 expression. Furthermore, DG1102 suppressed the activation of p38 and c-Jun N-terminal kinase (JNK). Our results suggest that DG1102 has an immune-modulatory activity suppressing production of pro-inflammatory cytokines and chemokine via the suppression of JNK and p38 MAPK activation in LPS-stimulated RAW 264.7 macrophages. The present study provides the biological evidence of the efficacy of medicinal plants in the treatment of inflammatory diseases

Atopic Dermatitis-Like Skin Lesions Reduced by Topical Application and Intraperitoneal Injection of Hirsutenone in NC/Nga Mice

Atopic dermatitis (AD) is a common inflammatory skin disease. The increasing prevalence and severity of AD have prompted the developments of safer, more effective drugs. Although topical corticosteroids have been used as first line therapy for AD, their potential side effects limit their clinical applications. To investigate the effect of hirsutenone (HIR), a diarylheptanoid compound, on AD-like skin lesions and other factors related to immune response is the aim of this paper Th2-related cytokines (IL-4, IL-5, IL-13), eosinophil, IgE inflammatory factors (COX-2, iNOS) levels were reduced in blood, lymphocytes, and tissue after HIR treatment. These results suggest that HIR might be an effective treatment for AD

Comparison of Monthly Ibandronate Versus Weekly Risedronate in Preference, Convenience, and Bone Turnover Markers in Korean Postmenopausal Osteoporotic Women

Patient preferences, convenience, and bone turnover markers were evaluated for the monthly ibandronate over the weekly risedronate regimen in Korean postmenopausal osteoporotic women. This was a 6-month, prospective, randomized, open-label, multicenter study with a two-period and two-sequence crossover treatment design. After a 30-day screening period, eligible participants with postmenopausal osteoporosis were randomized to receive either monthly oral ibandronate 150 mg for 3 months followed by weekly oral risedronate 35 mg for 12 weeks (sequence A) or the same regimen in reverse order (sequence B). Patient preference and convenience were evaluated by questionnaire. The changes in serum C-telopeptide after 3 months of treatment were analyzed. A total of 365 patients were enrolled in this study (sequence A 182, sequence B 183). Of patients expressing a preference (83.4%), 74.8% preferred the monthly ibandronate regimen over the weekly regimen (25.2%). More women stated that the monthly ibandronate regimen was more convenient (84.2%) than the weekly regimen (15.8%). There was no significant difference in the change in bone turnover marker between the two treatments. The two regimens were similarly tolerable. There were fewer adverse events in the monthly ibandronate group compared to the weekly risedronate group in terms of gastrointestinal side effects (nausea and abdominal distension). This study revealed a strong preference and convenience for monthly ibandronate over weekly risedronate in Korean postmenopausal osteoporotic women. There was no significant difference in change of bone turnover marker and safety profile between the two regimens