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At least 775 records · Page 43Linked to original sources
PubMed1998

An increase in the threshold of citric acid-induced cough during chest wall vibration in healthy humans.

This study tested the hypothesis that the afferent input from the respiratory muscles may be involved in the neural mechanisms inducing cough responses. Coughing was evoked in conscious healthy humans by the inhalation of citric acid aerosol of several concentrations either during or not during chest wall vibration (100 Hz) at the right second intercostal space or during vibration of the right thigh. The mean threshold citric acid concentration to induce coughing was significantly higher during chest wall vibration (geometric mean, 131.8 mg/ml) than without vibration (75.9 mg/ml). Vibration after topical anesthesia of the chest wall skin did not significantly change the threshold concentration of citric acid. The threshold citric acid concentration during vibration of the right thigh did not significantly differ from that without vibration. We concluded that inputs from the chest wall afferent, presumably from the intercostal muscle or costovertebral joint, may have an inhibitory effect on the initiation of coughing at the higher neural structure in conscious humans.

Administration, Inhalation↗
PubMed1998

Experimental studies of subjective response to road traffic-induced building vibration.

The road traffic-induced building vibration was recorded continuously for 24 hr in three orthogonal axes outside and inside the building. Several alternative objective methods of quantifying the severity of exposures to whole-body road traffic-induced building vibration are used. The relationship between the results of all objective evaluation methods of vibration-induced by road traffic and the subjective responses to building vibration are compared. It was conducted that the ISO 2631-2 z-axis frequency weighting combined with a measure of vibration dose value (VDV = [integral of a4(t) dt)]1/4 may use a practicable objective evaluation procedure in buildings than L10 percentile vibration levels. It was also cleared that the L10 percentile vibration levels at the ground boundary of the regulation law of Japan Environmental Agency must be low levels.

Building Codes↗
PubMed1998

Prevention strategy for vibration hazards by portable power tools, national forest model of comprehensive prevention system in Japan.

In the 1950s, the introduction of portable power tools into the production process of many industries began on a large scale around the world and resulted in many cases of occupational vibration syndrome after the 1960s. There was an urgent world wide need to undertake preventive steps, medical assessment and therapy. At the end of 1964, our investigation began in Japanese national forests, and then in mines and stone quarries. The Japanese Association of Industrial Hygiene established a "Committee for Local Vibration Hazards" (1965), and many researchers in the medical and technological fields joined this Committee. After 10 years, a comprehensive system for the prevention of vibration syndrome was established in the national forestry. It consists of 1) improvements in vibrating tools, 2) hygienic regulation of operation time with an alternative working system, 3) health care system involving early medical checks, early therapy and age limitations in operation of vibrating tools, 4) protection against cold in the workplace and while commuting, and 5) education and training for health and safety. The prevention strategy for vibration syndrome in our national forests is to establish a comprehensive prevention system in cooperation among researchers in the medical and technological fields, workers and administration. The Ministry of Labor presented that strategy as good model of prevention for other industries (1976). New designs for this model were developed and adapted according to the special conditions of each industry. Thus comprehensive system for prevention of vibration syndrome developed successfully from the late 1970s to 1980s in Japan.

Forestry↗
PubMed1998

Measurement of hand-transmitted vibration of tapping the long cane for visually handicapped people in Japan.

The long cane can be used as a mobility aid for visually handicapped people. According to a questionnaire completed by Japanese cane users, it seems they are not always satisfied with using long canes for a variety of reasons. In this study, hand-transmitted vibration from the long cane due to tapping the ground was measured because an exposure to repeated shock-type tapping vibration may affect the hand-arm system. A sighted female wearing a blindfold participated. The measurement was carried out in different conditions with three different ground materials both indoor and outdoors. The vibration at three axes of the cane grip and one axis at the wrist were measured. The pinch forces between an index finger and the grip were also measured using a strain gauge in order to observe how the vibration characteristics depend on the changing forces. Measurement, evaluation and assessment were based on the International Standard (ISO 5349). The estimated daily exposure time and the transmissibility were obtained in order to investigate the severity of the hand-transmitted vibration caused by the long cane. It was found that the characteristics of tapping vibration depend on different measurement conditions and the vibration might be associated with a health risk over a long life span.

Adult↗
PubMed1998

Momentary discomfort caused by vibration of railway vehicle.

When trains pass level crossings or turnouts, they are momentarily subject to relatively strong vibrations. In railway engineering, evaluation of the riding comfort under such occasional vibrations is called the momentary evaluation, which is distinguished from the long-term evaluation. In order to identify the effective vibrational characteristics on the momentary evaluation now controversial in Japan, an experiment was performed with a riding comfort simulator. Twenty adult subjects were exposed to lateral vibration with varying peak acceleration and crest factor. Referring to the vibrations of real trains, the peak acceleration in the range of 0.35-2.00 m/s2 were varied in steps of 0.35 m/s2 and the crest factors in the range of 1.5-5.0 were varied in steps of 0.5. The frequency was set constant at 2 Hz. The task was to rate the degree of discomfort under each vibration which was given them successively. Results indicate that changes in the peak acceleration are most effective, and application of the crest factor in parallel improves the correlation with the perceived discomfort. Whether subjects can perceive changes in the peak or not affects the evaluation. Weights of vibrational characteristics that make a cue to the evaluation by subjects differ from person to person.

Acceleration↗
PubMed1999

A study on the effects of countermeasures for vibrating tool workers using an impact wrench.

The aims of this study were (1) to measure frequency-weighted vibration acceleration and (2) to study the effects of introducing a vibration-proof impact wrench on VWF in workers. The subject pool was 383 male workers who were regularly using an impact wrench and taking special medical examinations for vibration syndrome in a factory from 1982 to 1999. The prevalence of workers with VWF increased gradually after 1982, reached a peak value (4.8%) in 1986, gradually decreased after 1987, and disappeared in 1994. Sixteen subjects who had had VWF at least one time during the observation period were selected for this study. The stages of VWF were at stage I on the Stockholm Workshop scale in all subjects. After the vibration-proof impact wrench was introduced in 1986, the vibration acceleration of the impact wrench measured on the handle decreased from 8.6-11.1 m/s2 to 5.1-7.1 m/s2. The actual time per day that subjects were assumed to use the impact wrench was 108 minutes. The subjects actually used an impact wrench more than the occupational exposure limit allowed. However, VWF disappeared after the introduction of a vibration-proof impact wrench. This might have resulted from the combined effect of introducing the vibration-proof impact wrench and certain countermeasures that were taken against cold working environments.

Adult↗
PubMed2001

A comparison of vibration magnitudes on the tool with different subject according to the ISO 8662-7 standard.

Recently, ISO has defined the guidelines for the evaluation of the measurement and exposure limits of hand-transmitted vibrations at the handle of hand-held portable power tools. In a measurement of vibrations at pneumatic impact wrenches that tighten and remove screws. ISO 8862-7 standard: 1997 and ISO 5349 standard: 1986 are set as international standards. In order to make an exact measurement of the quantities of vibrations exposed to the hand-arm system of a human body, ISO 8662-7 gives specifications to a measurement device and a loading device. As to a measurement device, for instance, the mass, installation method etc. of transducers and mechanical filters are defined. In addition, it specifies with each tolerance the working conditions of a pneumatic tool, the number of revolutions of socket in a loading device, the feed force, the number of subjects, and such an evaluation method as how to decide a declaration value of vibrations. These specifications give toolmakers a comparative measurement of vibration values of their tools before shipment. Meanwhile, although the measurement condition described in ISO8662-7: 1997 is that skilled operators conduct vibration measurement, no provisions as to operators are made in detail. Hence, this study focuses its concern on ambiguous work experience years in measuring vibrations of the tools in conformity with ISO 8662-7, and hereby the effect of years of work experience upon measurement values is considered and at the same time a knowledge of how to select operators is made clear.

Adult↗
PubMed1990

Hemodynamic changes in skin microcirculation induced by vibration stress in the conscious rabbit.

Cutaneous microcirculatory responses to vibration stress were observed by microphotoelectric plethysmography in a transparent round window installed in the ears of conscious rabbits. Vertical vibrations at frequencies ranging from 8 to 250 Hz were applied to the abdomen of the rabbits for 5 min. The vibrations produced an increase in heart rate and the index of discomfort, and a decrease in blood flow in the skin microcirculation. The maximum response was observed at 63 Hz. Rhythmic fluctuations in microcirculation were associated with two components: component A had a small amplitude and high frequency, and component B had a large amplitude and low frequency. Vibration exposure led to a large increase in component B and a smaller increase in component A. During vibration exposure, component A was suppressed by treatment with diltiazem, a calcium channel blocker, and was not affected by bunazosin, an alpha-1 adrenoceptor antagonist. The opposite changes were observed for component B. This indicates that components A and B of the rhythmic fluctuations are regulated by myogenic and neurogenic activities, respectively. Thus, the hemodynamic changes of skin microcirculation induced by vibration may actually be due to a neurogenic factor, especially sympathetic nerve activity. The responses appear to depend on the frequency of the vibrations.

Animals↗
PubMed1977

Transurethral stone extraction with a vibrating basket catheter.

In a recent in vitro study, mechanical vibration was shown to facilitate, considerably, both the passing of a basket catheter beyond an artificial ureteral stone as well as the extraction of a calculus. Therefore, a device by which vibration can be transmitted to the basket of a modified stone extractor was developed for clinical application. The basket moves to and fro with an amplitude of 2-4 mm and a frequency of 40-60 Hz. An experimental follow-up study was performed in dogs to find out whether the vibration procedure as such induced injuries to the ureters. Modified stone extractors were passed up bilaterally into the ureters of 11 dogs. Vibration was applied in a standardized manner to one side, the other non-vibrated side served as a control. Postoperatively, 5 dogs were followed during 4-5 weeks with repeated urographies. Specimens of the ureters were examined microscopically when the dogs were sacrificed. No complications which could be ascribed to the vibration procedure as such were observed. The vibration technique was tried also in a pilot study comprising 14 patients with distal ureteral stones; in 9 patients, the stones were successfully extracted. Of the remaining 5 patients in whom the stone extraction failed, 3 passed the stone spontaneously and in 2 ureterolithotomies were performed. No complications were encountered.

Animals↗
PubMed1999

[Morphological changes in the stria vascularis and hair cells after mastoid-vibration using a cutting bur].

Severe sesorineural deafness develops occasionally after tympanoplasty. Since a vibration induced by the drill during surgery is thought to be one of the cause, we examined its effect on the inner ear in this study. Five guinea pigs aged about 1 month were used. The right ear of each animal was used as the control, and the left ear underwent stimulation with the drill induced vibration. The vibration was applied to the temporal bone for 60 seconds using a cutting bur. After the vibration, the stria vascularis and hair cells in the cochlea were examined. For the investigation of the permeability of the stria vascularis, horseradish peroxidase (HRP) was injected intravenously as a tracer, and the tissue was observed with a light and an electron microscopes. Three sections of the stria vascularis from each of the superior turn (the third turn) and the inferior turn (the basal turn) of bilateral cochleae were randomly prepared, and they were classified into Types I to IV according to the degree of HRP leakage. When a hair cell had even one vacuole inside, it was classified as a vacuole-positive cell. After stimulation with the drill-induced vibration, about 10% of the blood vessels of the stria vascularis showed severe leakage of HRP (Types III, IV). In the intermediate cells, partial degeneration of mitochondria was found. No significant difference in the permeability of the blood vessels was found between the turns. The route of leakage of HRP from blood vessels of the stria vascularis was neither the transport via pinocytotic vesicle nor passage through the intercellular space of endothelial cells. The leakage through a tubular-like structure in the endothelial cells was observed. Since no HRP was found in this tubular-like structure ordinarily, a channel might have been opened by injury due to the vibration. The leakage from the blood vessels of the stria vascularis in the control side could scarcely be observed. Many hair cells in the drill-stimulation side in both the first and the third turns showed vacuoles with loss of intracellular structure. Slight loss of auditory hairs was found in this study, suggesting that the development of a vacuole was the first reaction to the drill-stimulation. Since the sensitivity toward stimulation of the drill-induced vibration was different among individual animals, it appears possible that the inner ear is injured in some cases without direct touch to the auditory ossicles owing to technical failure.

Animals↗
PubMed1993

Contribution of the tonic vibration reflex to muscle stress and muscle fatigue.

The aim of the investigation was to determine the influence of vibration displacement amplitude (200, 300 microns peak-to-peak), as opposed to acceleration effects at selected frequencies (40, 80, 100, 120, 150, 200 Hz), on a commonly observed but often undesired motor response elicited by local vibratory stimulation, that is, the tonic vibration reflex (TVR). Vibration was applied to the distal tendons of the hand flexor muscles. Changes in the activity of hand flexor and extensor muscles were analyzed as a function of both their initial contraction level (0, 10, 20% of maximal voluntary contraction) and the vibration parameters. The main results indicate that TVR increases with the initial muscle contraction and increases with vibration frequency up to 100-150 Hz but decreases beyond. High-frequency vibration seems to induce less muscle and tendon stress. This result is particularly important for the design of handheld vibrating tools.

Adult↗
PubMed1987

Intraneural edema following exposure to vibration.

Peripheral neuropathy represents a well-known complication from long-term exposure to vibration. In the present study an experimental model is presented with the purpose of analyzing the formation of intraneural edema following vibration exposure. Vibration (82 Hz, peak-to-peak amplitude 0.21 mm) was induced in the hind limb of rats by the use of vibrating electric motors during 4 h/d for 5 d. Tracer techniques (with albumin Evans blue and horseradish peroxidase) were used to study the permeability of intraneural microvessels after the vibration exposure on day 5. It was found that the vibration trauma in this model induced epineurial edema in the sciatic nerve. It is hypothesized that the formation of intraneural edema may be an important pathophysiological factor in the occurrence of vibration-induced neuropathy.

Animals↗
PubMed1987

Bone and joint pathology in workers using hand-held vibrating tools. An overview.

A literature evaluation was made with regard to the radiological documentation of bone and joint pathology in the hands and arms of workers using vibrating tools. There is evidence that work with pneumatic percussive tools (such as chipping hammers and scalers) may cause premature elbow and wrist osteoarthrosis, although of very low prevalence. This work-related disorder is not specific to vibration exposure. Instead, it is likely to result from the strong dynamic and static joint loading (often in extreme positions of the joint) and the repetitive hand-arm movements (sometimes also repeated minor traumatization) typical for tool manipulation in any heavy labor. Exposure to low-frequency percussion may, however, play a particular etiologic role: damage to the joint cartilage by repeated shocks from the tool, additional articular load (and consequent strain) associated with a vibration-induced increase in the need for joint stabilization and higher gripping forces, the tonic vibration reflex (which increases muscle contraction), and a stronger grip induced when tactile sensibility is diminished by vibration. So far, no investigations have ventured into the great complexity of possible confounders and effect modifiers. -A constitutional susceptibility may be required to produce osteoarthrosis. -The allegation that hand-arm vibration exposure causes an excess prevalence of bone cysts, vacuoles, Kienböck's disease, or pseudarthrosis of the scaphoid has not been validly documented. -Exposure to vibration of higher frequencies (such as from rotating drills, grinders, and chain saws) does not seem to be associated with excess bone and joint pathology. -The observed large variation in the prevalence of skeletal disorders may be explained by biodynamic and ergonomic differences between various occupations.

Arm↗
PubMed1987

Clinical assessment of suspected damage from hand-held vibrating tools.

The case history is still the cornerstone in the clinical assessment of suspected vibration injury. Objective tests to verify the symptoms are needed for legal reasons in insurance cases and for research purposes. The minimum requirement of a test used to obtain objective signs of Raynaud's phenomenon is that patients with vibration-induced white finger be evaluated along with symptom-free, but vibration-exposed, subjects for reference. The measurement of systolic blood pressure in the finger after local finger and general body cooling is a test that has been evaluated in this way, as has restitution of finger temperature after local cooling and ischemia combined with general body heating. If neurological symptoms are present, electroneurographic examination is essential since carpal tunnel syndrome, a treatable condition, is common in vibration-exposed patients. Measurements of vibration and temperature thresholds are complementary examinations. The so-called vibrogram may be a method with which to obtain objective neurological signs of vibration injury, but the test needs further evaluation. Until more is known of the pathophysiological mechanisms behind the disease, the patient's description of his symptoms, combined with a detailed exposure history, will remain essential for a diagnosis of vibration injury--irrespective of the results of the tests used.

Carpal Tunnel Syndrome↗
PubMed1986

Handlebar vibration of a motorcycle during operation on different road surfaces.

In Japan daily motorcycle mail deliverers have been exposed to vibration from the handlebars of their motorcycles. Handlebar vibration was measured during the operation of a motorcycle in order to evaluate the hazardous effects of vibration and to identify preventive measures against the vibration hazards. Tests were made on asphalted, unpaved, and packed-snow road surfaces. The tested motorcycles were selected from the many motorcycles in daily use. The test motorcycle was a 1-cylindered, 89-cm3, 4-cycle machine. The direction showing the maximum value of vibration acceleration was not always in the directions of X, Y, and Z proposed by the International Organization for Standardization (ISO). The maximum vibration acceleration level exceeded the exposure guideline of ISO, while its frequency corresponded to that of the engine speed during operation. Vibration of greater than 20 Hz was transmitted through the front forks from the road surface and tires.

Fingers↗
PubMed1986

Transmission of hand-arm vibration to the head.

A "tooth impression" was devised to measure head vibration. The vertical head vibration of four subjects was measured with the tooth impression during exposure of the hand to vertical sinusoidal vibration at acceleration levels of 3.15, 10.0, and 31.5 m/s2 root mean square in the range of 8-200 Hz. While in a standing position, the subjects pulled the vibrating handle upward at a force of 5 kg with the elbow joint stretched during the tests. The measurement was repeated twice. The difference between the two measurements was within 3 dB, a level which suggests that this method has good reproducibility. The vibration transmitted to the head was the greatest in the range of 12.5-16 Hz, and the attenuation was about 20 dB. Head vibration decreased by approximately 15 dB per octave at frequencies above 20 Hz as the frequency increased. When the excitation level was increased by 10 dB, the head vibration increased by about 8 dB.

Adult↗
PubMed1999

Sister chromatid exchange analysis in workers exposed to noise and vibration.

BACKGROUND: There has been a growing interest in the combined effects of noise and vibration. In a population of aeronautical workers diagnosed with vibroacoustic disease (VAD), a large incidence of malignancy was detected. These workers were exposed to large pressure amplitude (LPA) (> or = 90 dB SPL) noise, with energy content concentrated within the low frequency (LF) bands (< or = 500 Hz) and whole-body vibration (WBV). To our knowledge, there are no studies conducted in humans or animals that address the issue of the potential genotoxic effects of vibration combined with noise. In the present study, the levels of sister chromatid exchanges (SCE) and of cells with high frequencies of SCE (HFC) were analyzed in peripheral blood lymphocytes of workers employed in various occupations within the aeronautical industry. METHODS: SCE and HFC were analyzed in lymphocytes of 50 workers occupationally exposed to noise and vibration and of 34 office-worker controls (G0). The exposed group included: 10 hand-vibrating tool operators (G1), 15 engine test cell technicians (G2), 12 aircraft run-up technicians (G3) and 13 Portuguese Air Force helicopter pilots (G4). Groups 2-4 were exposed to WBV and LPALF noise; group 1 was exposed to LPA high frequency noise and local vibration. Statistical analysis of the mean SCE count per cell was carried out by multiple regression analysis comparing various predictor variables: type of exposure, duration of exposure, age, and cigarette consumption. RESULTS: Only cigarette consumption and type of exposure were found to be significantly correlated with the mean SCE frequency. After allowing for the effects of smoking, the analysis indicates that: 1) there was no significant difference between G1 and G0 (p > 0.05); 2) the differences between G2 and G0, G3 and G0, G4 and G0 were all highly significant (p < 0.001); 3) there was no significant difference between G2 and G3 (p > 0.05), nor between G2 and G3 combined and G4 (p > 0.05); and 4) G2 and G4 combined had a significantly elevated mean SCE frequency compared G0 (p < 0.001). Statistical analysis of the proportion of HFC was consistent with these results. CONCLUSION: Our data suggest that occupational exposure to LPALF noise and WBV may lead to increased levels of SCE in men. These results also suggest a reason for the high incidence of malignancy in VAD patients. The observed effects may not reflect a direct action of these physical agents on DNA. Alternative explanations may lie in the noise-, vibration-, and/or stress-induced pathophysiological changes.

Adult↗
PubMed1999

Models of the apparent mass of the seated human body exposed to horizontal whole-body vibration.

BACKGROUND: Many environments contain vibration with simultaneous vertical and horizontal components. Mathematical lumped parameter models of the mechanical impedance of the seated human body have previously been defined for exposure to vertical vibration. This paper proposes models for the response of the seated body when exposed to horizontal vibration. METHODS: Four target functions were derived from previously reported measurements of the apparent masses of seated subjects exposed to fore-and-aft and lateral vibration at both 0.5 and 1.0 ms(-2) r.m.s. Parameters were optimized for six different three degree-of-freedom models to fit the modulus of the model responses to the four target functions. RESULTS: The modulus and phase of the apparent masses optimized for all combinations of vibration magnitude and direction were close to the responses previously measured and reported in the literature. Fitted parameters for all models with elements in series showed at least one element with a parameter that tended to zero. CONCLUSIONS: Models with three parallel single degree-of-freedom systems with a rigid support generally gave the closest representation of the apparent mass of the seated body exposed to horizontal vibration. More experimental data on the effect of gender, posture and magnitude of vibration on the apparent masses of seated subjects would be useful to enable these models to be improved.

Adult↗