Characterization of human mitochondrial PDSS and COQ proteins and their roles in maintaining coenzyme Q10 levels and each other's stability.

Mutations of many PDSS and COQ genes are associated with primary coenzyme Q10 (CoQ10) deficiency, whereas mitochondrial DNA (mtDNA) mutations might cause secondary CoQ10 deficiency. Previously, we found that COQ5 and COQ9 proteins are present in different protein complexes in the mitochondria in human 143B cells and demonstrated that COQ5 and COQ9 knockdown suppresses CoQ10 levels. In the present study, we characterized other PDSS and COQ proteins and examined possible crosstalk among various PDSS and COQ proteins. Specific antibodies and mitochondrial localization of mature proteins for these proteins, except PDSS1 and COQ2, were identified. Multiple isoforms of PDSS2 and COQ3 were observed. Moreover, PDSS1, PDSS2, and COQ3 played more important roles in maintaining the stability of the other proteins. Protein complexes containing PDSS2, COQ3, COQ4, COQ6, or COQ7 protein in the mitochondria were detected. Two distinct PDSS2-containing protein complexes could be identified. Transient knockdown of these genes, except COQ6 and COQ8, decreased CoQ10 levels, but only COQ7 knockdown hampered mitochondrial respiration and caused increased ubiquinol:ubiquinone ratios and accumulation of a putative biosynthetic intermediate with reversible redox property as CoQ10. Furthermore, suppressed levels of PDSS2 and various COQ proteins (except COQ3 and COQ8A) were found in cybrids containing the pathogenic mtDNA A8344G mutation or in FCCP-treated 143B cells, which was similar to our previous findings for COQ5. These novel findings may prompt the elucidation of the putative CoQ synthome in human cells and the understanding of these PDSS and COQ protein under physiological and pathological conditions.

Prevalence and psychosocial risk factors of upper extremity musculoskeletal pain in industries of Taiwan: a nationwide study.

Prevalence of upper extremity disorders and their associations with psychosocial factors in the workplace have received more attention recently. A national survey of cross-sectional design was performed to determine the prevalence rates of upper extremity disorders among different industries. Trained interviewers administered questionnaires to 17,669 workers and data on musculoskeletal complaints were obtained along with information on risk factors. Overall the 1-year prevalence of neck (14.8%), shoulder (16.6%), and hand (12.4%) disorders were higher than those of the upper back (7.1%) and elbow (8.3%) among those who sought medical treatment due to the complaint. Workers in construction and agriculture-related industries showed a higher prevalence of upper extremity disorders. After multiple logistic regression adjusted for age, education, and employment duration, we found job content, physical working condition, a harmonious interpersonal relationship at the workplace and organizational problems were significant determinants of upper extremity disorders in manufacturing and service industries. Male workers in manufacturing industries showed more concern about physical working conditions while female workers in public administration emphasized problems of job content and interpersonal relationships. We concluded that these factors were major job stressors contributing to musculoskeletal pain of the upper extremity.

Effects of flange size on dividing streamlines of exterior hoods in cross drafts.

Effects of flange size on the flow patterns of an exterior circular hood subject to the influence of various uniform cross drafts were studied in an apparatus consisting of hood-model/wind-tunnel assembly. The cross draft to suction velocity ratio covered the range from 0.056 to 0.792. The flange width to hood diameter ratio spanned from 1.2 to 3.0. The hood equipped without flange was also probed. A two-component laser Doppler anemometer was used to measure the velocity field on the symmetry plane. The streamline patterns were obtained from the measured velocity data. The cross draft caused a capture envelope. The boundary of the envelope was described by a dividing streamline. It was found that the flange width presented complex effects on the capture envelope and the dividing streamline. Corresponding to a cross draft to suction velocity ratio, a critical flange width existed. If the flange width was smaller than the critical value, the dividing streamline would terminate at the downstream tip of the flange. The behaviors of the capture envelope and the dividing streamline of the hood in cross draft under different flange widths are presented and discussed.

Occupational health research in Taiwan.

This article gave a brief introduction of population, labor force, general status of occupational safety and health in Taiwan. Statistics of occupational injuries and health disorders, laws and regulations relevant to occupational health were also covered. Research activities driven by universities, research institutes, society/association were provided. Two multi-lateral collaborative research examples were presented: an intoxication outbreak-initiated CS2 study and an information-demand-motivated 2-methoxy-ethanol study. Industrial hygienists, engineers, epidemiologists, and occupational physicians from both universities and research institutes, governmental agencies, and from non-profit R&D organizations and academic associations were involved in these researches, presenting a promise that integrated collaboration of inter-disciplinary specialty cooperated with governmental participation could benefit not only academic achievement, governmental policy-makeup, but also to the employees themselves.

Prevalence of musculoskeletal disorder among workers in Taiwan: a nationwide study.

Musculoskeletal disorder (MSD) is a common problem among workers. In spite of the numerous reports on MSD in various specific groups of workers, few data on the prevalence in the general working population are available except for back pain. We analyzed the information collected through a nationwide survey in Taiwan in 1994 to estimate the prevalence of MSD by age, gender, and education level and identify high-risk industries. In the survey, a standard questionnaire was distributed to a representative sample of 22,475 non-self-employed workers in Taiwan. National estimates were obtained by applying a weight to each participant. Among the sampled workers, 18,942 (84.3%) participated, and 37.0% (standard error=0.4%) had MSD. Female workers had a significantly higher overall prevalence than male workers (39.5% vs. 35.2%, p<0.05). Education and age also had significant associations with MSD (p<0.001 in both genders). "Lower back and waist" were the most frequently affected body parts (18.3% among males and 19.7% among females), but the prevalence of MSDs of the neck, shoulders, hands and wrists were also above 10%. The top ten high-risk major industries for MSD of various body parts for each gender were identified, and some industries, including "Basic Metal Industries" and "Buildings Construction," were among the top ten for multiple body parts. Our study showed that MSDs of body parts other than the back are also prevalent, especially in the neck, shoulders, hands and wrists. We also identified high-risk industries for further research and intervention.

Musculoskeletal disorders in hotel restaurant workers.

BACKGROUND: A variety of occupational groups have been shown to experience elevated risks of work-related musculoskeletal disorders (WMSD). Little information on WMSD is available in hotel restaurant workers. OBJECTIVE: To document the profile of WMSD in a sample of hotel restaurant workers in Taiwan. METHODS: A self-administered questionnaire was used to gather information regarding body site specific WMSD, pain intensity and strategies for pain relief amongst a sample of hotel restaurant workers. RESULTS: Among 905 restaurant workers, 785 (84%) reported experience of WMSD in the previous month, with the highest prevalence rate found for the shoulder (58%). The highest mean score for perceived pain intensity was found for the lower back/waist (2.50 points). Despite a high prevalence rate, only a small portion of those reporting WMSD (12%) considered their work capacity or activities of daily living to be affected by WMSD, and only <5% of workers with WMSD sought medical treatment. CONCLUSION: WMSD related pain is common among hotel restaurant workers in Taiwan, but it does not appear to interfere with job performance or daily living. Self-treatment and alternative therapies that have not been evaluated for effectiveness are commonly employed by hotel restaurant workers.

Development and characterization of a wake-controlled exterior hood.

A wake-controlled exterior hood was developed to overcome the negative influence of cross draft on an exterior hood and avoid the operation inconvenience caused by the enclosure of an airflow capture booth. This new type of local exterior hood used the hood suction flow to stabilize the dynamic vortex shedding that was induced when a crossflow passed over a blockage plate, and therefore formed a hydrodynamics-stabilized local isolation area for efficient removing of the contaminant. The development process was performed in a test section of an open-circuit wind tunnel. The blockage plate and the exterior hood model were placed in a wind-tunnel test section so that the crossflow could be freely supplied by the airstream of the wind tunnel. The laser light sheet flow visualization method and the laser Doppler velocimeter were employed to reveal the characteristics of the flow field. Primary influential parameters were factored out of the measured velocity results so that a design procedure was proposed. Experiments using hot-wire type alcohol sensors to measure the toluene vapor concentration distributions showed that the capture efficiency of this type of actively controlled hood was remarkably higher than that of an uncontrolled hood.

Evaluating the efficacy of a thermal exposure chamber designed for assessing workers' thermal hazard.

This study was conducted on a thermal exposure chamber designed for assessing workers' thermal hazard. In order to assess the efficacy of the studied chamber, three environmental conditions were selected to simulate high, middle and low thermal impact situations, with air temperatures (Ta) of 43.12, 36.23 and 25.77 masculine C, globe temperatures (Tg) of 44.41, 41.07 and 29.24 masculine C, relative humidity (RH) of 77, 59 and 39%, and air flow velocities (Va) of 1.70, 0.91 and 0.25 m/s, respectively. For the three specified thermal impact conditions, results show that the coefficients of variation (CVs) for Ta, Tg, RH and Va measured in the chamber studied were consistently less than 10%, except for Va under the low thermal impact condition (=50%). For each specified thermal impact condition, we generated 1,000 environmental combinations by using the Monte Carlo simulation approach according to the variations obtained from the four environmental factors. We directly adopted the ISO 7933 approach to estimate the allowable exposure time (AET) for each simulated environmental condition. This study yielded a range in the 95% confidence interval (95% CI) of the estimated AETs for the three specified thermal impact conditions which were consistently less than 5 min. We further conducted the sensitivity analysis to examine the effect of the four environmental factors on estimating AETs. We found Va was the least important factor in estimating AETs for any specified thermal impact condition. In conclusion, although Va was found with great variation for the chamber specified in the low thermal impact condition, the exposure chamber studied can still be regarded as a feasible one for assessing workers' thermal hazard.

Heat stress evaluation and worker fatigue in a steel plant.

This study assessed fatigue in electric arc melting workers (ER) and continuous casting workers (CC) in a steel plant and evaluated their physiological response to different levels of heat stress. Fifty-five men participated in the study. The ER group (mean, standard deviation [SD]=41.6, 7.4 years) was significantly older than the CC group (34.9, 6.4 years). The wet bulb globe temperature (WBGT) index of the workplace was measured. Workers' subjective fatigue symptoms were investigated by a 30-item constructive questionnaire, and physiological conditions and response time were measured before and after work for 2 consecutive days. WBGT ranged from 25.4 approximately 28.7 degrees C and 30.0 approximately 33.2 degrees C for the CC and ER areas, respectively. After age adjustment the ER group had significantly higher prevalence rates in subjective symptoms and slower response time than the CC group. The response "thirsty" was the highest after work (75 and 60% for the 2 ER interview days, respectively). A high prevalence (over 40%) of "eyes feel strained," "perception of shoulders stiff," or "feel waist pain" also was observed. Average pre- and postwork ER group systolic pressures were 129.1+/-11.4 mmHg (mean+/-SD) and 126.1+/-12.1 mmHg, 132.5+/-11.4 and 130.6+/-11.2 mmHg for the CC group. Continuous heat-strain monitoring data from one ER and one CC worker indicated that average working heart rate and body temperature were well below 150 beats/min and 38 degrees C. Faster response in critical flicker fusion was found after work than before work, but the differences were not statistically significant (p>.05). Response time for the falling bar grasp was faster at the beginning of work, declined with working time, and rebounded at the end of work. Workers exposed to a hot environment are inclined to subjective fatigue, and their fatigue symptoms increase with the heat exposure levels. However, low resting heart rate and systolic pressure are two characteristics for high heat exposure workers.