Iwao Hirosawa

Availability of temperature sense indices for diagnosis of vibration disease

SummaryThe correlation between stages of vibration disease and hypesthesia of temperature sense detected with our thermo-esthesiometer was analyzed. We measured the warm and cool thresholds among operators (644 males) in three occupational categories with vibration exposure from hand-held vibratory tools, such as grinder, drill, sander, impact-wrench, bush-cutter and chain-saw. Through the examination of the relationship between the temperature threshold and the stage of vibration disease, the following was revealed: The warm sense threshold elevated parallel with the aggravation of vibration disease, although the skin temperature had no change or reduction. The hypesthesia of the cool sense threshold appeared in serious cases of vibration disease. This abnormality of the cool sense indicated a more intensive disorder than that detected by the warm sense abnormality. The width of the neutral zone between the warm and cool thresholds of the intact subjects was 6.6° C±3.8 C°. This neutral zone was enlarged with the aggravation of the vibration disease. Data also showed that the measurements of temperature sense threshold should be carried out under standardized room temperature.

Temporary threshold shift of temperature sensation caused by vibration exposure

SummaryThe temporary threshold shift of temperature sensation due to vibration exposure was studied to clarify the significance of frequency and acceleration on it. The discrete frequencies of the vibrations tested were 32, 63, 125, 250 and 500 Hz, and the accelerations were at the level of 2, 4, 8 and 16 g. The threshold shift of warm sensation (TTSw) was markedly, but that of cool sensation was small and not significantly different from the control value. TTSw increased with a rise in the level of acceleration and was largest at 125 Hz among the frequencies examined. The most effective frequency among the vibrations tested for warm sensation was inferred to be lower than that for vibratory sensation. After exposure, TTSw or the increment of the neutral zone decayed exponentially but bounced slightly in the later period. These patterns of TTSw are similar to those of the vibration-induced TTS of vibratory sensation.

Original construction of thermo-esthesiometer and its application to vibration disease

SummaryA thermo-esthesiometer was devised for the investigation of sensory disorders among operators of vibration tools. Moreover, its usefulness for diagnosis was investigated. The esthesiometer was composed of a copper pipe 80 cm long that was heated at one end with an electric heater and chilled at the other end with a cooling mixture of NaCl and ice. The temperature at each point of the copper pipe was measured using a sliding surface-thermometer. It gave a sigmoidal temperature gradient between 8.5° and 47.5°C at a room temperature of 20°C. It took about 30 min to complete a stable temperature gradient from the start of heating and cooling. The profile of the temperature gradient curve was a function of room temperature. The stability of the temperature gradient curve was to be maintained satisfactorily for more than 5 h at a constant room temperature below 28°C. The size of this apparatus, when it was broken up, was small enough to carry around easily. Using this esthesiometer, the warm and cool thresholds were measured at the fingertips of operators of vibration tools. From the results obtained the hypesthesia of temperature sense was shown to correlate very strictly with the stage of vibration disease. In particular, an upward deviation of warm threshold and an increase of the width of the neutral zone were observed in those patients.

Effects of Catechol on Human Subjects

SummaryPhysical examination was carried out on 13 workers exposed to vapours of catechol and phenol. The intensity of exposure was such that the average concentrations of catechol and phenol were 1.8 ppb and 55.6 ppb, respectively, with an occasional peak up to 70 ppb and 260 ppb, respectively. Chief complaints of the workers were related to upper respiratory tract, such was confirmed by CMI Health Questionnaire as well as by clinical examination. Possible disturbance of catecholamine metabolism, haematopoiesis, or hepatic and renal functions was ruled out. Biological half-life of catechol, calculated from the result of the factory survey and rat experiments, was comparable to that of phenol. No evidence was obtained to suggest metabolic inhibition between phenol and catechol. Colorimetric method for determination of catechol in air and in urine in the presence of phenol is described.

Evidence for an Acceleration of Programmed Cell Death in Bronchiolar Epithelium after Exposure to O, O, S-Trimethyl Phosnhorothioate

Evidence for an Acceleration of Programmed Cell Death in Bronchiolar Epithelium after Exposure to O, O, S‐Trimethyl Phosphorothioate: Akio Koizumi, et al. Akita University School of Medicine—Exfoliation of Clara cells is a prelude to pathological alterations after exposure to a variety of toxicants. The reported morphological features of exfoliating Clara cells share similarity with some types of programmed cell death (PCD). The purpose of the present study is to characterize morphological changes in Clara cells in the process of PCD in physiological and pathological conditions. We used 0,0,S‐trimethyl phosphorothioate (OOS‐TMP) as a lung toxicant. Morphological changes in the lungs of control rats and rats killed at 2 to 48 hr after treatment with OOS‐TMP (po. 60 mg/kg) were investigated by electron microscopy. In situ DNA‐ fragmentation was determined by 3’‐OH end labeling in these rats. Immunoelectron microscopy was conducted to examine the morphological changes in Clara cells in PCD. Exfoliation of Clara cells started at 2 hr after dosing. At 6 hr, many Clara cells were sloughed. In situ DNA‐fragmentation positive cells were detected in the bronchiolar epithelium of both control and treated rats. Their relative incidences increased 13 fold by 6 hr and returned to basal levels by 48 hr. In contrast, no positive cells were detected in the alveolar cells of either group. Positive cells in the bronchiolar epithelium were identified exclusively as Clara cells. The ultrastructure of the DNA‐ fragmentation positive cells revealed similar changes in control and treated rats. DNA‐fragmentation, a hallmark of PCD, was detected in Clara cells of both control and treated rats, but not in alveolar cells. The relative increases in the DNA‐fragmentationpositive cells suggest an acceleration in PCD after treatment with OOS‐TMP. The results of this study indicate that different mechanisms of cellular death occur in Clara and alveolar cells in response to toxic insults. This difference most likely reflects the cell‐ specific mode of the action of lung toxicants.

THE ANNUAL CHANGES OF VIBRATION HAZARDS IN THE LUMBERJACKS OF STATE FORESTS

Since 1958, with the labor rationalization policy of the state forests, chain-saws have been widely introduced in the felling operation of trees. Chain-saws have often caused damage to operators as have other vibrating tools such as drills, hammers and grinders. It was negotiated between labor and management in 1969 that one can not operate the chain-saw more than 2hr per day for the prevention of hazards, furthermore, that persons with vibration hazards, particularly white waxy hands, should not continue to use the chain-saw and to receive medical treatment with the recognition of the hazards as prescribed occupational hazards and with the displacement of their occupations.Medical examinations were carried out on the lumberjacks of the State Forests in Yamaguchi Prefecture for 6 years since 1970. In the present study, the effects of the time regulation of the use of chain-saw on the symptoms and the progress of the symptoms of serious cases after discontinuing the use of chain-saw were investigated. It was found that the regulation of operation time scarcely affected the symptoms, Peripheral blood circulation and peripheral nerve sensation were still impaired with the use of chain-saw. The complaints of the finger numbness, and of the systemic indisposition had increased each year.On the other hand, the progress of the symptoms after discontinuing the use of chain-saw resulted in a tendency of a decrease of the Raynauds phenomenon and recovery of the peripheral blood circulation and the peripheral nerve sensation, whereas the finger numbness still continued. Therefore it is necessary to find out a more satisfactory measure in the medical treatment of these hazards.Now every lumberjack has given up the use of chain-saw and has started to use an ax and a saw again. There are used freely by persons with vibration hazards as well as by the others. We are worried about the effects of ax impacts and vibrations and of strained posture leading to cervicobrachical syndrome and of low back pain. It seems to be necessary to consider preventive measures against these injuries.