Assessment of hand-arm vibration exposure among traffic police motorcyclists

 The aims of this study were (1) to evaluate subjective symptoms in the hand-arm system of all traffic police motorcyclists of a city located in the central part of Japan and (2) to assess their hand-arm vibration exposure associated with traffic police motorcycle riding. The study population consisted of 119 motorcycling traffic policemen and 49 male controls. By means of a questionnaire, information on the occupational history and the presence of subjective symptoms in the hand-arm system of all subjects was obtained. Vibration was measured on the handlebars of the representative motorcycles and on the hands of the riders. The 4- and 8-h energy-equivalent frequency-weighted acceleration as well as the lifetime vibration dose were calculated for all police motorcyclists. The prevalence of finger blanching in the traffic police motorcyclists was 4.2%, but none of the controls had this symptom. The rates of finger numbness (19.3%), finger stiffness (16.0%), shoulder pain (13.4%), and shoulder stiffness (45.4%) were significantly higher among police motorcyclists as compared with controls. The root-mean-square (rms) frequency-weighted acceleration on the handlebars of police motorcycles was in the range of 2.2–4.9 m/s² rms. The computed 4- and 8-h energy-equivalent frequency-weighted acceleration values were 2.8– 4.5 and 2.0 –3.2 m/s² rms, respectively. A pattern of increasing percentage prevalence with increasing cumulative vibration dose was noticed. The subjects with a lifetime vibration dose of more than 20.1 m² h ³ s^-4 (ln scale) showed significantly higher prevalence rates for symptoms in the fingers and shoulders as compared with the control group. As occupational vibration exposure of traffic police motorcyclists might be considered a risk factor for the development of symptoms in the hand-arm system of the riders, its evaluation and control is needed for prevention methodology evolution. Received: 15 April 1996/Accepted: 8 November 1996     

Effects of Maharishi Amrit Kalash 5 as an Ayurvedic herbal food supplement on immune functions in aged mice

Background  

Maharishi Amrit Kalash (MAK) 5, one of the Ayurvedic food supplements, belongs to a group of substances known as Rasayana. MAK5 and other Rasayanas are believed to enhance the body's resistance to infections and disease, and enhance longevity. In this study, we determined the effects of administration of MAK5, one of the Ayurvedic food supplements on immune functions in young and old mice.     

Purification and characterization of urease isolated from the pathogenic fungus Coccidioides immitis.

Coccidioides immitis, the causative agent of San Joaquin Valley fever (coccidioidomycosis), produces a urease which has been suggested to contribute to the virulence of this fungal pathogen. Urease catalyzes the hydrolysis of urea and has been proposed to at least partly account for alkalinity of the microenvironment in which C. immitis grows due to the release of ammonia and ammonium ions. The C. immitis urease was purified to homogeneity (1048-fold) from the mycelial cytosol by chromatographic fractionation. The sequence of 12 N-terminal amino-acid residues of the purified, native polypeptide was identical to that predicted by the translated urease gene sequence which has been reported. The isolated enzyme exhibited a specific activity in the presence of urea of 1750 micromol min(-1) mg(-1) protein, has a native molecular mass of 450 kDa, revealed a Km for urea of 4.1 mM, had a pH optimum of 8.0 and is heat stable. Hydroxyurea, acetohydroxamic acid (AHA) and boric acid each inhibited activity of the purified enzyme. Urease activity was enhanced by the presence of 5-10 mM concentrations of Mg2+ or Mn2+, but inhibited by Li+, Ni2+, Cu2+ or Zn2+. The reversible urease inhibitor, AHA, blocked enzyme activity in the crude mycelial cytosolic fraction when added at a concentration of 10 mM. On the other hand, 10 mM AHA added to 4-day-old mycelial cultures only partially decreased the amount of ammonium detected in the culture medium. It is evident, therefore, that C. immitis urease activity does not account for the total amount of ammonia secreted during in vitro growth of the pathogen. Other metabolic sources of ammonia, which may also contribute to the virulence of C. immitis, are under investigation.     

Hand-arm vibration syndrome and its prevalence in the present status of private forestry enterprises in Japan

Summary Currently there are no limitations on age of employment on private forestries in Japan. Hence, it was hypothesized that in these kind of enterprises, elderly chain saw operators, or those with long-term exposure, might be at higher risk of developing hand-arm vibration syndrome (HAVS). We consequently investigated the prevalence of HAVS in 447 chain saw workers on private forestries in Gifu Prefecture, Japan, with particular reference to age and exposure period. Of this population, 43 (9.6%) had signs and symptoms of vibration-induced white finger (VWF), and among these workers the severity of finger blanching was significantly correlated (P < 0.01) with the exposure period. Classification of all subjects by exposure period showed that workers with 30 years' exposure had higher prevalences of VWF (20.9%) and numbness of the hands (25.4%) compared to other groups. Significant differences (P < 0.01) were found between the functional capacities of workers with VWF and those of control subjects. We concluded that (a) the elderly chain saw operators and those with longer exposure should be moved to other jobs with a lower or no risk of exposure to vibration, and (b) the results of screening tests, even without cold water immersion (which we did not employ, in order to protect workers' hands), could be helpful for the identification of workers with VWF.     

A study on the vibration-dose limit for Japanese workers exposed to hand-arm vibration.

To obtain a vibration-dose limit for Japanese workers exposed to hand-arm vibration, the prevalences of vibration-induced white finger (VWF) and numbness of the hand were studied in 5 different groups of workers exposed to segmental vibration. In addition, the prevalence of primary Raynaud's phenomenon (PRP) in the general population without occupational vibration exposure was computed. The vibration levels in the exposed groups (except chain saw operators) ranged from 124.1-129.2 dB (reference value, 10(-6) m/s2). The prevalence of VWF in these groups was 2.2-4.8%. This value was not statistically significant (p greater than 0.05) when compared to the prevalence of PRP in the general Japanese population (2.7-2.9% in our study and 0.5-4.6% in other surveys in Japan). Although the prevalence of numbness of the hands fluctuated among the groups, no significant differences could be demonstrated. Our results were then compared to those of previous reports by literature study [319 papers on hand-arm vibration syndrome (HAVS) and 25 reports on PRP]. At a glance the Japanese population showed a lower prevalence for PRP compared to other countries, which suggested that exposure to cold and biological abilities should also be considered to assess vibration syndrome. A comparison of the vibration characteristics of different tools and the occurrence of VWF in the hands of workers in the literature with those of our data suggested that a daily hand-arm vibration exposure at a level lower than 2.5 m/s2 (128 dB, reference value 10(-6) m/s2) could possibly decrease the risk of VWF among workers exposed to segmental vibration.     

Raynaud's phenomenon and cutaneous changes due to hand-arm vibration

Vibration of hand-held tools is considered to induce disorders in the peripheral circulation, peripheral nerve and organs, muscles, bones and joints (vibration syndrome). Above all, Raynaud's phenomenon is known as a prominent sign of vibration syndrome. This paper describes the findings obtained from the observation of the skin of the hands exposed to vibration and evaluates the relation between Raynaud's phenomenon and cutaneous changes. A total of 124 chain-saw workers in a forestry company in Gifu Prefecture were investigated in connection with compulsory health examination. In medical occupational interview, every worker was asked whether he had any experience of Raynaud's phenomenon or not. Moreover, the following symptoms of the skin and nails of the hand(s) were examined: 1. sclerodactylia, 2. pitting scar, 3. edema, 4. erythema around the nail, and 5. elongation and bleeding of proximal nailfolds and cuticles. To determine whether vibration induces the above mentioned cutaneous changes, the relation between the prevalence of the changes and the duration of exposure to vibration was assessed. The workers were classified into four groups by duration of exposure to vibration (in intervals of 10 years). The evaluation was made by comparing the prevalence of cutaneous changes between the workers with Raynaud's phenomenon and those without it. Subjects were restricted in age from 40 to 59 years. There was a significant relationship between age and duration of exposure (p less than 0.001). The prevalence of Raynaud's phenomenon was significantly high among the workers in the fifties (15.8%). The prevalence of Raynaud's phenomenon was significantly increased in workers with longer exposure. The prevalence of Raynaud's phenomenon was 6.9% in workers in the forties. Though the prevalence of sclerodactylia and elongation and bleeding of proximal nailfolds and cuticles was higher in workers in the fifties than those in the forties, (1. 34.7% in the 50 s, 24.1% in the 40 s 5. 27.4% in the 50 s, 17.2% in the 40 s), no relation could be demonstrated between the duration of exposure and the prevalence of cutaneous changes. There were no significant differences in the prevalence of cutaneous changes between the workers with Raynaud's phenomenon and those without Raynaud's phenomenon.     

Cutaneous signs (Raynaud's phenomenon,sclerodactylia, and efladema of the hands) and hand-arm vibration exposure

Summary Dermatological tests and examinations of the hand(s) were carried out in vibration-exposed and un exposed males. The subjects were 179 chain-saw workers in private forestry companies and 205 local inhabitants who had never used vibrating tools. The prevalences of Raynaud's phenomenon (RP), sclerodactylia, and edema of the hands were estimated in both groups, and associations between these cutaneous signs and vibration exposure were evaluated. The prevalences of RP and edema in the exposed group were 9.5% and 1.7%, respectively, and in the unexposed group, 2.9% and 1.5%, respectively. Sclerodactylia was seen in 31.8% of the chain-saw workers but in only 6.4% of the unexposed individuals. In statistical analyses based on unconditional logistic regression models with adjustment for age, RP was associated with long-term ( 20 years) vibration exposure [odds ratio (OR) = 7.06; 95% confidence interval (CI) = 2.51–19.87]. Sclerodactylia was associated with both short- and long-term vibration exposure (OR = 6.54, Cl = 3.30-13.36; OR = 7.05; CI = 3.41-14.60, respectively). There were significant dose-response relationships between RP and duration of exposure and between sclerodactylia and duration of exposure. Results of function tests indicated a longer recovery time and a higher vibration threshold for the workers with RP. The presence of sclerodactylia, however, did not have any significant influence on function test results. It is possible to conclude that not only RP but also sclerodactylia could be induced by vibration exposure. However, most cases of sclerodactylia were not so serious as to involve disturbances of peripheral circulatory and nerve function.     

Comparison of subjective symptoms and hot prevention measures in summer between traffic control workers and construction workers in Japan

In the present study, a survey on subjective symptoms and hot prevention measures in summer was conducted in 204 male traffic control workers and 115 male construction workers. Work loads of traffic control workers and construction workers were estimated at RMR 1-2 and RMR 2-4, respectively. A self-administered questionnaire was used to collect information on age, occupational career, working habit, present or past history of diseases, individual preventive measures to the heat, and subjective symptoms in the summer. Daily working hours in the sunshine of the traffic control workers were significantly longer than those of the construction workers. Prevalence rates of changing clothes frequently, avoiding direct exposure of face and neck to sunlight using towel like materials, and wearing sunglasses in the traffic control workers were significantly lower than the construction workers. Prevalence rates of symptoms in the upper extremities in the traffic control workers were significantly lower than those in the construction workers. Prevalence of work difficulty due to hot weather during work in the traffic control workers was significantly lower than the construction workers. On the basis of the results obtained, some preventive countermeasures to improve working environment are presented.     

Immunohistochemical study of vestibular gingival blood vessel density and internal circumference in smokers and non-smokers.

BACKGROUND: This study was undertaken to determine: 1) if sections stained with monoclonal antibody to CD34 can be used for measurement of gingival blood vessel density and circumference and 2) if long-term smoking affects either of these 2 parameters. METHODS: Vestibular gingival biopsy samples were obtained from 17 adults (5 smokers and 12 non-smokers) who were undergoing routine periodontal surgery independently of this study. Hematoxylin and eosin staining was used for histological assessment of inflammation, while immunohistochemical staining with CD34 mouse monoclonal antibody was used to mark the endothelial cells of the blood vessels within each sample. Stringent selection criteria were applied to the 17 biopsy samples, and 7 (from 3 smokers and 4 non-smokers) were chosen to have their vascular density (number of vessels/unit area) and internal vessel circumference (IC) measured under a blinded protocol. RESULTS: Repeated measurements of vascular density and internal circumference showed small standard deviations, indicating the high reproducibility of the measurement technique. The smoker group showed a higher proportion of small (IC < 50 microns) and a lower proportion of large blood vessels (IC > 100 microns), which was statistically significant (P = 0.0403 and P < 0.001, respectively). The difference between the vascular density of smokers and non-smokers was not significant (P = 0.092). CONCLUSIONS: The present study indicates that the CD34 immunohistochemical staining technique is a simple and reproducible method for the measurement of density and internal circumference of gingival blood vessels. Based on this technique, cigarette smokers show a higher percentage of smaller blood vessels and a lower percentage of larger vessels, but similar vascular density, to non-smokers.