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Biomedical subjects

R Inaba

Publications and source records attributed to R Inaba.

At least 73 records · Page 4Linked to original sources
PubMed1991

Experimental studies on the effects of vibration and noise on sympathetic nerve activity in skin.

Multi-unit sympathetic activity was recorded at elbow level from median nerve fascicles supplying glabrous skin of the left hand in five healthy subjects. The resultant vasomotor responses accompanying the neural activity were monitored by simultaneous recordings of skin blood flow using the laser doppler method and skin temperature in the innervation zones. No significant change in sympathetic activity was observed during handgrip exercise of the right hand under a constant gripping force of 2 kg. Subjects maintained the same gripping force of the right hand during exposure in random order to local vibration and/or noise, each type of exposure lasting 5 min with intervals of 20 min. A two-peaked significant increase in outflow from sympathetic nerves was observed during local exposure of the right hand to vibration with a frequency of 60 Hz and an acceleration of 50 m.s-2, followed by a postexposure period which revealed a relative suppression of sympathetic nerve activity and a significant increase in blood flow. Noise at 100 dB(A) showed only an initial effect on skin sympathetic nerve activity (SSA), whereas when combined with local vibration at 60 Hz, a pronounced increase in neural activity was noticed, indicating a combined effect of vibration and noise. These results from direct recordings of SSA suggest a sympathetic vasomotor reflex mechanism triggered by local vibration stimuli to the hand.

Adult↗
PubMed1991

[Effects of whole-body microwave exposure on the plasma adrenocorticotropic hormone, thyroid-stimulating hormone and thyroid hormones in rats].

To investigate the effects of whole-body microwave exposure on plasma adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), thyroxine (T4) and free triiodothyronine (T3) levels, rats weighing 267-306 g (light group) and 352-387 g (heavy group) were exposed to microwaves with a frequency of 2,450 MHz at the power densities of 5 and 10 mW/cm2 under an ambient temperature of 21 degrees C to 23 degrees C for an hour. Rectal temperatures were increased by 1.0 degrees C at 5 mW/cm2 and 2.1 degrees C at 10 mW/cm2 in the light group, and by 0.7 degrees C at 5 mW/cm2 and 1.5 degrees C at 10 mW/cm2 in the heavy group after microwave exposure. Plasma levels of ACTH increased significantly at 10 mW/cm2 in the light group and 5 and 10 mW/cm2 in the heavy group after microwave exposure. Plasma levels of TSH increased significantly at 10 mW/cm2 only in the light group. As for plasma levels of free T3, a significant decrease at 10 mW/cm2 was observed only in the heavy group. However, plasma levels of T4 did not change in either group after microwave exposure.

Adrenocorticotropic Hormone↗
PubMed1991

[Changes of peripheral blood parameters in aerobic dance instructors after aerobic dance instruction].

To investigate the biological load of aerobic dance instruction on the body, a blood biological study was performed on 13 female instructors. The values were compared with 10 female healthy controls. The results obtained were as follows. 1. A significant negative correlation was observed between the total experience of aerobic dancing (in years) and the levels of serum phospholipids. In addition, the numbers of white blood cells and the levels of serum phospholipids, lipoperoxide, uric acid and creatinine were significantly related to aerobic dance instruction time (years). 2. The levels of serum CPK, aldolase, GOT, BUN and creatinine in the aerobic dance instructors were significantly higher than those in the controls. 3. The levels of serum CPK, uric acid, BUN, creatinine and Ca increased significantly after an intermediate class lesson (about 60 minutes). In addition, the numbers of white blood cells also increased after the lesson, but not significantly. Moreover, Significant decreases of the mean corpuscular volume and serum Mg were observed after the lesson.

Adult↗
PubMed1991

[Analysis of subjective symptoms of upper extremities in dental technicians].

Our review of the literature showed no report on the subjective symptoms of the upper extremities in dental technicians. This study was therefore undertaken on 164 dental technicians in Gifu Prefecture to investigate the relationship between the subjective symptoms of the hands, arms and shoulders and work of dental technicians. The following results were obtained. 1) The prevalence of Raynaud's phenomenon and numbness of the fingers was 5.5 and 18.5 %, respectively. A significant positive correlation was observed between the prevalence and frequency of numbness and cold sensation in the fingers and the daily usage time (h) of high-speed type machines. In addition, pain in the fingers and around the wrists, and pain and numbness in the arms were significantly related to the daily usage time (h) of low-speed type machines. These results suggest that the usage of high- and low-speed type machines may be a cause of vibration syndrome among dental technicians. 2) A high prevalence of pain in the shoulders (30.8%), neck (30.1%), and back (36.3%) was observed in dental technicians. It is considered that these symptoms are related to the working posture and usage of machines.

Adult↗
PubMed1990

Carpal tunnel syndrome in vibration disease.

The presence of carpal tunnel syndrome (CTS) in 125 forestry workers with exposure to vibration was examined clinically by electromyography and by determining vibration detection thresholds. Numbness of the hands was present in 43%, history of diminished hand muscle force in 15%, and Raynaud's phenomenon in 27%. The muscle weakness correlated significantly with motor nerve conduction velocity in the median nerve in both hands. In 25 forestry workers CTS was diagnosed. The condition was bilateral in 48%; otherwise it was more common on the right side. Fifteen patients were referred for surgery but because of spontaneous recovery or refusal by the patients only five underwent surgery; of these four improved. The motor conduction velocity of the ulnar nerve was decreased among patients with CTS supporting the idea that entrapment neuropathies in the hands may be due to tissue swelling caused by vibration at work. Total exposure time to vibration correlated with the decrease in motor conduction velocity in the ulnar nerve.

Adult↗
PubMed1990

[Effects of whole-body microwave exposure on the plasma corticosterone, glucose, uric acid and allantoin levels in rats].

To investigate the effects of whole-body microwave exposure on plasma corticosterone, glucose, uric acid and allantoin levels, rats weighing 245-300 g (light group) and 440-510 g (heavy group) were exposed to microwaves with a frequency of 2,450 MHz at the power density of 10 mW/cm2 under an ambient temperature of 21 to 23 degrees C for one hour. Rectal temperatures were increased by 3.4 degrees C in the light group and 1.4 degrees C in the heavy group after microwave exposure. Plasma levels of corticosterone, glucose and uric acid did not change in both groups after microwave exposure. Plasma levels of allantoin increased significantly only in the heavy group after microwave exposure. These results suggest that the plasma levels of allantoin, a metabolite of uric acid, may be useful as a biological variable for assessment of the effects of whole-body microwave exposure in rats. The increase of plasma allantoin level after microwave exposure could not be explained only by the degree of increased rectal temperature caused by hyperthermic effects of microwaves.

Allantoin↗
PubMed1989

Risk factors in the genesis of sensorineural hearing loss in Finnish forestry workers.

A detailed analysis of risk factors for the development of sensorineural hearing loss (SNHL) was carried out in 199 forest workers. The hearing threshold of both ears at 4000 Hz was measured, and the effect of age, exposure to noise, blood pressure, presence of vibration induced white finger (VWF), tobacco smoking, plasma LDL-cholesterol concentration, and consumption of drugs were evaluated by multiple linear regression analysis. Aging was the major risk factor, followed by exposure to occupational noise and the presence of VWF. Plasma LDL-cholesterol concentration and the use of antihypertensive drugs also correlated significantly with SNHL. These main factors were able to explain about 28% of the SNHL variance. Additional factors in the analysis, including smoking, systolic and diastolic blood pressure, and consumption of salicylates did not significantly contribute to the genesis of SNHL.

Age Factors↗
PubMed1988

[Effects of local vibration exposure on whole blood viscosity in rats].

To investigate the relationship between vibration hazards and blood viscosity, vibration exposure experiments were conducted. The rat's hind limbs were continuously exposed to local vibration (60 Hz, 5 G) for 4 h. The exposed group showed a slightly lower blood viscosity and plasma fibrinogen in the blood obtained immediately after exposure when compared with the control group. However, in the blood obtained 18 h after exposure, there was no significant difference in the levels of whole blood viscosity and plasma fibrinogen between the exposed group and the control group. Hematocrit was not affected by this exposure. These results indicate that the decrease in the levels of whole blood viscosity induced by local vibration exposure is transient and that some relationship exists between changes of whole blood viscosity and those of plasma fibrinogen.

Animals↗
PubMed1988

Evaluation of factors affecting sensory neural hearing loss.

A detailed analysis of risk factors in the development of sensory-neural hearing loss (SNHL) was carried out in 199 forest workers. The mean hearing threshold of both ears at 4000 Hz was measured and the effect of age, exposure, blood pressure, presence of vibration induced white finger (VWF), tobacco smoking and plasma lipid concentrations on SNHL were evaluated by multiple linear regression analysis. A part of aging the major risk factors were presence of VWF, elevation of LDL-cholesterol level and usage of antihypertensive agents. Additional factors in the analysis, e.g. smoking and diastolic and systolic blood pressure did not significantly contribute to the genesis of SNHL.

Age Factors↗
PubMed1988

Effects of low- and high-frequency local vibration on the occurrence of intimal thickening of the peripheral arteries of rats.

Rats were exposed to local vibration in a study of the differences in the effects between low and high frequencies of vibration on the vessel wall of peripheral arteries. The vibration was delivered at frequencies of 30 and 480 Hz under a constant acceleration of 5g. The duration of the vibration exposure was 30 d. The changes in the arteries were studied pathohistologically and hematologically. Three of the five rats exposed to 30 Hz and three of the five rats exposed to 480 Hz showed disruption of the internal elastic lamina. The disruption was followed by focal cell proliferation with regenerative formation of collagen and elastic fibers. The vascular changes observed after vibration exposure could not be explained by changes in plasma lipid concentrations. These results suggest that not only low frequencies of vibration, but also high frequencies have harmful effects on the intima of small arteries.

Animals↗
PubMed1988

Protection against the lethal effects of whole body vibration by the alpha-adrenergic system in rat.

To investigate the protective mechanism against the lethal effect of whole body vibration, the phentolamine (1 mg/kg) pretreated rats were exposed to whole body vibration with a frequency of 20 Hz under an acceleration of 5 G at 24 +/- 2 degrees C and 5 +/- 1 degrees C. Five of 9 rats pretreated with phentolamine died from the exposure to whole body vibration within one hour at 24 +/- 2 degrees C. In these rats, marked infrapleural hemorrhage, dilatation of alveolar capillary vessels, and intraalveolar hemorrhage and edema were observed. However, all of the 10 rats pretreated with saline survived through the one hour exposure to the same vibration, and showed only slight histological changes in the lung. On the other hand, no rats pretreated with saline or phentolamine died from the exposure to whole body vibration within one hour at 5 +/- 1 degrees C. These results suggest that the alpha-adrenergic system and cold have a role of protection against the lethal effects of whole body vibration.

Animals↗
PubMed1987

Occurrence of intimal thickening of the peripheral arteries in response to local vibration.

Experiments were performed to elucidate a possible mechanism for the peripheral circulatory disturbance caused by vibration. Rats were exposed to local vibration (60 Hz, 5 G) on their hind legs for four hours a day for 30 days or 90 days. With exposure for 30 days the small arteries at the exposed site did not change. With exposure for 90 days, however, disruption of the internal elastic lamina was observed in the small arteries. This disruption was followed by focal cell proliferation with regenerative formation of collagen and elastic fibres. The fibrocellular thickening of the intima was further augmented, and in addition a complete stenosis of the lumen of the small arteries was observed. Electron micrography showed that the fibrocellular thickening of the intima consisted of a proliferation of arterial smooth muscle cells and numerous collagen and elastic fibres. These alterations were not observed in the arteries of the controls. The thickness of the media did not differ between the control and exposed groups or in animals with different durations of exposure. Concerning plasma total cholesterol, HDL-cholesterol, and lipoperoxide, there were no significant differences between the control and exposed groups after either 30 or 90 days, but the whole blood viscosity was significantly increased by day 90. This finding may be related to the intimal thickening.

Animals↗
PubMed1987

Usefulness of blood parameters, especially viscosity, for the diagnosis and elucidation of pathogenic mechanisms of the hand-arm vibration syndrome.

In the present study it was found that, in vibrating-tool operators with Raynaud's phenomenon, whole blood viscosity was significantly higher than in operators without Raynaud's phenomenon at shear rates from 230 to 11.5 s-1. In addition rats were experimentally exposed to local vibration (60 Hz, 5 g) on their hind limbs for 4 h/d for 30 or 90 d. In the case of 30-d exposure, the small arteries in the exposed site did not change. However, after exposure for 90 d, disruption of the internal elastic lamina was observed in the small arteries. The disruption was followed by focal cell proliferation with regenerative formation of collagen and elastic fibers. The fibro-cellular thickening of the intima was further augmented, and, in addition, a complete stenosis of the small lumen of the small artery was observed. Medial thickness did not show significant differences between the control and exposed groups for either exposure duration. The whole blood viscosity was significantly increased by the 90-d but not by the 30-d exposure. These results suggest that there are some relationships between the increase in whole blood viscosity and the intimal thickening of some small arteries in the exposed site.

Animals↗