Masaru Miyao

Overhead work and shoulder-neck pain in orchard farmers harvesting pears and apples

The effects of overhead work were studied by comparing orchard farmers musculoskeletal symptoms while bagging pears with those same symptoms while bagging apples. The subjects were 52 Japanese female farmers, who were examined twice an evening in late June for bagging pears, and during another evening of late July for bagging apples, when each task had been almost finished. They were questioned about musculoskeletal complaints of stiffness and pain during each job, and examined for muscle tenderness and pain from joint movement. Arm elevation angles during the work were measured for each type of bagging. The prevalence of stiffness and pain in the neck and shoulder, muscle tenderness in the shoulder regions, and pain in neck motion were found to be significantly higher when bagging pears than apples. Musculoskeletal symptoms of parts other than the neck and shoulder did not differ between the two types of bagging. The working posture of elevating the arm more than 90 degrees was assumed to account for 75% of the time bagging pears, against 40% for bagging apples. Overhead work requiring arm elevation and head extension was considered to be closely related with shoulder-neck disorders among farmers.

Effect of vibration frequency on finger blood flow

SummaryA total of 18 healthy subjects (9 men and 9 women) 20–35 years of age were used to study the effect of vibration frequency on finger blood flow. Seven vibration frequencies of 16, 31.5, 63, 125, 250, 500 and 1,000 Hz, at vibrational accelerations of 10 m/s2 (rms: root mean square) or 50 m/s2 (rms), with the exception of 16 Hz, which was measured at only 10 m/s2 (rms), were randomly applied to the palm of the right hand for 1 min at intervals of about 3 min. Finger blood flow was measured simultaneously in both the right and the left middle fingers with a blood flowmeter using a thermal diffusion method and in the left middle finger with a laser Doppler flowmeter. The experiments were performed in an artificial climate chamber set at 23°C air temperature and 50% humidity. Relatively great responses were observed at frequencies of 31.5–63 and 250–500 Hz on the exposed and unexposed sides, respectively, as measured with a blood flowmeter using a thermal diffusion method and at 31.5–63 as well as 500 Hz on the unexposed side with a laser Doppler flowmeter. These results may be related to Meissners and pacinian corpuscles.

Skin sympathetic activity in the tibial nerve triggered by vibration applied to the hand

SummaryThe effect of vibration applied to the hand on skin sympathetic activity (SSA) in the lower limbs was studied in five healthy subjects. SSA from the right tibial nerve at the popliteal fossa, plethysmogram from the right index toe and perspiration from the sole of the rigth foot were measured when vibration of 100m/s2 at 60 Hz was applied to the left palm for 1 min. The SSA response to vibration exposure differed among subjects, but every subject showed an increase in SSA from the tibial nerve when vibration was applied to the hand. Decrease in amplitude of plethysmogram from the toe was also found in all subjects. One subject displayed a remarkable increase in perspiration on the sole of the foot together with a great increase in SSA. The present findings indicated that even vibration exposure of the hand triggers sympathetic activity in the tibial nerve innervating the foot, and causes vasoconstriction of the toe and perspiration on the sole of the foot.

Correlation between vibration-induced white finger and symptoms of upper and lower extremities in vibration syndrome

SummaryThe correlation was investigated between the frequency of attacks of vibration-induced white finger (VWF) and numbness or coldness of the fingers and legs in patients with vibration syndrome. Some 1687 patients with vibration syndrome were examined and of these 342 chain-saw operators and 277 rock-drill operators had no disease other than vibration snydrome. Then subjects were matched by age and period of treatment within three years. In the last analysis, 20 in the VWF “almost everyday” group or in the “never” group, and 40 in the “occasionally” group were selected from the chain-saw operators, and from the rock-drill operators 32 in the VWF “everyday” or the “never” group and 64 in the “occasionally” group. The present study showed that, with the frequency of VWF attacks, patients had a higher prevalence of coldness not only in the fingers but also in the legs. These findings suggest a correlation between the severity of circulatory disturbances of the upper extremities and that of the lower ones in patients with vibration syndrome. Further studies on circulatory disturbances in the leg are required.

Relation between overhead work and complaints of pear and apple orchard workers

The relation between working posture in overhead work and the complaints of farmers cultivating pears and apples were investigated by comparing pear work with apple work. The same 20 male and 28 female orchard workers were questioned about complaints associated with thinning out pears and bagging them, and bagging apples. The angle of forward flexion in the shoulder and neck extension was also measured in each job. The prevalence of tiredness, stiffness and pain in the neck, shoulders and arms was significantly higher in thinning out pears and bagging them than in bagging apples. Dizziness and tinnitus among female workers was more frequent in thinning pears. The posture of raising arms and bending the head backwards was higher in thinning and bagging pears. These results suggest that the working postures of elevated arms and backward head bending can cause symptoms in the neck, shoulders and arms. In some cases, they may also lead to symptoms of vertebral artery insufficiency.

Circulatory disturbances of the foot in vibration syndrome

SummaryCirculatory disturbances of the foot in patients with vibration syndrome were studied by measuring the skin temperature of both index fingers and great toes through a 3-min immersion of the right foot in cold water at 10°C. Subjects included 11 patients with vibration-induced white finger (VWF) [VWF(+) group], 12 patients without VWF [VWF(−) group], and 20 healthy referents not exposed to vibration. Patients were all male chain saw operators who had scarcely been exposed to vibration of the foot. The prevalence of coldness felt in the upper and lower extremities was > 90% in the VWF(+) group, about 60% in the VWF(−) group, and < 10% in the referents. The extent of the coldness was greatest in the VWF (+) group. The skin temperature of both fingers and toes was lowest in the VWF(+) group, somewhat higher in the VWF(−) group, and highest in the referents both before and after immersion. These findings indicate that patients with vibration syndrome, especially those with VWF, have circulatory disturbances in the foot as well as in the hand. The disturbances in the foot may be related to long-term repeated vasoconstriction in the foot induced by hand-arm vibration through the sympathetic nervous system.

Tuberculosis among the homeless people of Nagoya, Japan

A survey was conducted in order to clarify the tuberculosis (TB) situation in the homeless during the period from 1982 to 1991 in an urban district of Nagoya, using the registration cards of pulmonary TB patients and the data of chest roentgenograms of the Nagoya City Nakamura Health Centre. The incidence and prevalence of pulmonary TB per 100,000 among the homeless were estimated at 950-2150 and 1900-3250, respectively, which were around 30 and 20 times higher than those for the non-homeless. An increase in the incidence rate among homeless pulmonary TB patients was found in 1989, after a gradual decrease to the year 1988. The detected prevalence rate by chest examinations of the homeless was also around 30 times higher than that for the non-homeless. The percentage of patients with cavities indicated by chest roentgenograms when they were first registered was 76.9% among the homeless, but only 42.9% among the non-homeless.

Combined effects of vibration and noise on palmar sweating in healthy subjects

SummaryThe combined effects of vibration and noise on palmar sweating were studied experimentally in healthy subjects. Ten subjects were exposed to vibration at an acceleration of 100 m·sec−2 root mean square at a frequency of 125 Hz, a noise level of 105 dB(A) at a frequency of 1000 Hz and both stimuli together. Vibration was applied to the right hand and noise to both ears from headphones. Palmar sweating was measured by the ventilated capsule method. Vibration caused a marked increase in palmar sweating of the right hand directly exposed to vibration and also of the left hand not exposed to vibration. Simultaneous vibration and noise caused a greater increase in palmar sweating than by each of the factors separately. The combined effects tended to be greater in subjects who were more susceptible to vibration or noise.

Family clusters of pulmonary tuberculosis in a suburban area of Japan

A survey was conducted in a metropolitan suburb to examine family clusters of pulmonary tuberculosis patients and related factors. Firstly, a descriptive study was done based on the review of tuberculosis registration cards over a 11-yr period. Of 1106 cases, 109 (9.9%) were found to occur in households which had already had one or more pulmonary tuberculosis patient during the period. The most affected were four- and eight-member families with infants and adolescents accounting for most of the second or later patients. Secondly, a home visit survey was performed to investigate factors associated with family clusters of phthisis. Results showed that significant variables were the length of patients delay (interval between perception of physical symptoms and visit to the physician), the number of rooms, and lack of self-motivation to seek treatment. Log-linear analyses revealed interaction among these variables.

Psychology of computer use. XXX: Effects of presentation speed on pupil size using negative and positive CRTS

The effects of presentation speed and both positive and negative CRT (cathode ray tube) displays on pupil size were studied. The pupillary areas of 12 female student volunteers were measured by infrared videopupillography. The three presentation speeds were no change for 12 sec., a change every 2 sec. for 12 sec., and a change every 1/2 sec. for 12 sec. Two-way analysis of variance showed that the pupil size in the negative displays was significantly larger than that in the positive displays. A difference in pupillary area results from different display speeds, irrespective of a difference in polarity.