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Krajnak K, Warren C, Xu X, Chapman P, Waugh S, Boots T, Welcome D, Dong R. Applied Force Alters Sensorineural and Peripheral Vascular Function in a Rat Model of Hand-Arm Vibration Syndrome. J Occup Environ Med 2024; 66:93-104. [PMID: 37903602 PMCID: PMC10921367 DOI: 10.1097/jom.0000000000002998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2023]
Abstract
OBJECTIVE This study described the effects of applied force (grip) on vascular and sensorineural function in an animal model of hand-arm vibration syndrome (HAVS). METHODS Rat tails were exposed to 0, 2, or 4 N of applied force 4 hr/d for 10 days. Blood flow and sensitivity to transcutaneous electrical stimulation and pressure were measured. RESULTS Applied force increased blood flow but reduced measures of arterial plasticity. Animals exposed to force tended to be more sensitive to 250-Hz electrical stimulation and pressure applied to the tail. CONCLUSIONS Effects of applied force on blood flow and sensation are different than those of vibration. Studies examining co-exposures to force and vibration will provide data that can be used to determine how these factors affect risk of workers developing vascular and sensorineural dysfunction (ie, HAVS).
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Affiliation(s)
- Kristine Krajnak
- From the Physical Effects Research Branch, National Institute for Occupational Safety and Health, Morgantown, West Virginia
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Moore KD, Wu JZ, Krajnak K, Warren C, Dong RG. Quantification of mechanical behavior of rat tail under compression. Biomed Mater Eng 2024; 35:337-349. [PMID: 38758990 DOI: 10.3233/bme-230170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2024]
Abstract
BACKGORUND The development of vibration-induced finger disorders is likely associated with combined static and dynamic responses of the fingers to vibration exposure. To study the mechanism of the disorders, a new rat-tail model has been established to mimic the finger vibration and pressure exposures. However, the mechanical behavior of the tail during compression needs to be better understood to improve the model and its applications. OBJECTIVE To investigate the static and time-dependent force responses of the rat tail during compression. METHODS Compression tests were conducted on Sprague-Dawley cadaver rat tails using a micromechanical system at three deformation velocities and three deformation magnitudes. Contact-width and the time-histories of force and deformation were measured. Additionally, force-relaxation tests were conducted and a Prony series was used to model the force-relaxation behavior of the tail. RESULTS The rat tails' force-deformation and stiffness-deformation relationships were strongly nonlinear and time-dependent. Force/stiffness increased with an increase in deformation and deformation velocity. The time-dependent force-relaxation characteristics of the tails can be well described using a Prony series. CONCULSIONS We successfully quantified the static and time-dependent force responses of rat tails under compression. The identified mechanical behavior of the tail can help improve the rat-tail model and its applications.
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Affiliation(s)
- Kevin D Moore
- Physical Effects Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety & Health, Morgantown, WV, USA
| | - John Z Wu
- Physical Effects Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety & Health, Morgantown, WV, USA
| | - Kristine Krajnak
- Physical Effects Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety & Health, Morgantown, WV, USA
| | - Christopher Warren
- Physical Effects Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety & Health, Morgantown, WV, USA
| | - Renguang G Dong
- Physical Effects Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety & Health, Morgantown, WV, USA
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Dong RG, Warren C, Xu XS, Wu JZ, Welcome DE, Waugh S, Krajnak K. A novel rat-tail model for studying human finger vibration health effects. Proc Inst Mech Eng H 2023; 237:890-904. [PMID: 37345449 PMCID: PMC10557186 DOI: 10.1177/09544119231181246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/23/2023]
Abstract
It has been hypothesized that the biodynamic responses of the human finger tissues to vibration are among the major stimuli that cause vibration health effects. Furthermore, the finger contact pressure can alter these effects. It is difficult to test these hypotheses using human subjects or existing animal models. The objective of this study was to develop a new rat-tail vibration model to investigate the combined effects of vibration and contact pressure and to identify their relationships with the biodynamic responses. Physically, the new exposure system was developed by adding a loading device to an existing rat-tail model. An analytical model of the rat-tail exposure system was proposed and used to formulate the methods for quantifying the biodynamic responses. A series of tests with six tails dissected from rat cadavers were conducted to test and evaluate the new model. The experimental and modeling results demonstrate that the new model behaves as predicted. Unlike the previous model, the vibration strain and stress of the rat tail does not depend primarily on the vibration response of the tail itself but on that of the loading device. This makes it possible to quantify and control the biodynamic responses conveniently and reliably by measuring the loading device response. This study also identified the basic characteristics of the tail biodynamic responses in the exposure system, which can be used to help design the experiments for studying vibration biological effects.
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Affiliation(s)
- Ren G Dong
- Physical Effects Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health (NIOSH), Morgantown, WV, USA
| | - Christopher Warren
- Physical Effects Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health (NIOSH), Morgantown, WV, USA
| | - Xueyan S Xu
- Physical Effects Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health (NIOSH), Morgantown, WV, USA
| | - John Z Wu
- Physical Effects Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health (NIOSH), Morgantown, WV, USA
| | - Daniel E Welcome
- Physical Effects Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health (NIOSH), Morgantown, WV, USA
| | - Stacey Waugh
- Physical Effects Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health (NIOSH), Morgantown, WV, USA
| | - Kristine Krajnak
- Physical Effects Research Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health (NIOSH), Morgantown, WV, USA
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Degan GA, Antonucci A, Coltrinari G, Lippiello D. Problems related to measuring the transmissibility of anti-vibration gloves. Possible efficacy for impact tools used in mining and quarrying activities. INTERNATIONAL JOURNAL OF OCCUPATIONAL SAFETY AND ERGONOMICS 2022; 29:704-716. [PMID: 35475952 DOI: 10.1080/10803548.2022.2070334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
AbstractThis commentary takes into account some of the most relevant studies investigating the transmissibility of anti-vibration (AV) gloves. AV gloves are almost useless at the palm level in the low frequencies (less than 31.5 Hz), while they generally start to have an appreciable reduction of the vibration over 400 Hz. In their use with impact tools, having a low dominant vibration frequency usually between 25-60 Hz for chipping hammers and drills, and less than 30 Hz for pneumatic breakers, the average transmissibility reduction at the palm level is 13% (min 2% - max 26%) when used with hammers, and 1% (increment of 4% and reduction of 6%) when used with breakers. The transmissibility at the finger level, especially in the low frequencies, is almost nothing or produces an increase of the vibration. Other problems related to the increase of the applied force and the reduction of dexterity are reported.
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Affiliation(s)
| | | | | | - Dario Lippiello
- Department of Engineering, University of Roma Tre, Rome, Italy
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Dong RG, Wu JZ, Xu XS, Welcome DE, Krajnak K. A Review of Hand-Arm Vibration Studies Conducted by US NIOSH since 2000. VIBRATION 2021; 4:482-528. [PMID: 34414357 PMCID: PMC8371562 DOI: 10.3390/vibration4020030] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Studies on hand-transmitted vibration exposure, biodynamic responses, and biological effects were conducted by researchers at the Health Effects Laboratory Division (HELD) of the National Institute for Occupational Safety and Health (NIOSH) during the last 20 years. These studies are systematically reviewed in this report, along with the identification of areas where additional research is needed. The majority of the studies cover the following aspects: (i) the methods and techniques for measuring hand-transmitted vibration exposure; (ii) vibration biodynamics of the hand-arm system and the quantification of vibration exposure; (iii) biological effects of hand-transmitted vibration exposure; (iv) measurements of vibration-induced health effects; (iv) quantification of influencing biomechanical effects; and (v) intervention methods and technologies for controlling hand-transmitted vibration exposure. The major findings of the studies are summarized and discussed.
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Affiliation(s)
- Ren G. Dong
- Physical Effects Research Branch, Health Effects Laboratory Division (HELD), National Institute for Occupational Safety and Health (NIOSH), Morgantown, WV 26505, USA
| | - John Z. Wu
- Physical Effects Research Branch, Health Effects Laboratory Division (HELD), National Institute for Occupational Safety and Health (NIOSH), Morgantown, WV 26505, USA
| | - Xueyan S. Xu
- Physical Effects Research Branch, Health Effects Laboratory Division (HELD), National Institute for Occupational Safety and Health (NIOSH), Morgantown, WV 26505, USA
| | - Daniel E. Welcome
- Physical Effects Research Branch, Health Effects Laboratory Division (HELD), National Institute for Occupational Safety and Health (NIOSH), Morgantown, WV 26505, USA
| | - Kristine Krajnak
- Physical Effects Research Branch, Health Effects Laboratory Division (HELD), National Institute for Occupational Safety and Health (NIOSH), Morgantown, WV 26505, USA
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Can Blood Flow be Used to Monitor Changes in Peripheral Vascular Function That Occur in Response to Segmental Vibration Exposure? J Occup Environ Med 2020; 61:162-167. [PMID: 30507789 DOI: 10.1097/jom.0000000000001509] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Laser Doppler blood flow measurements have been used for diagnosis or detection of peripheral vascular dysfunction. This study used a rat tail model of vibration-induced vascular injury to determine how laser Doppler measurements were affected by acute and repeated exposures to vibration, and to identify changes in the Doppler signal that were associated with the exposure. METHODS Blood flow was measured immediately after a single exposure to vibration, or before vibration exposure on days 1, 5, 10, 15, and 20 of a 20 days exposure. RESULTS After a single exposure to vibration, average tail blood flow was reduced. With 20 days of exposure, there was a reduction in the amplitude of the arterial pulse on days 10 to 20 in vibrated rats and days 15 to 20 in control rats. CONCLUSIONS More detailed statistical analyses of laser Doppler data may be needed to identify early changes in peripheral circulation after exposure to vibration.
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Zimmerman JJ, Bain JLW, Wu C, Lindell H, Grétarsson SL, Riley DA. Riveting hammer vibration damages mechanosensory nerve endings. J Peripher Nerv Syst 2020; 25:279-287. [PMID: 32443170 DOI: 10.1111/jns.12393] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 05/06/2020] [Accepted: 05/16/2020] [Indexed: 11/28/2022]
Abstract
Hand-arm vibration syndrome (HAVS) is an irreversible neurodegenerative, vasospastic, and musculoskeletal occupational disease of workers who use powered hand tools. The etiology is poorly understood. Neurological symptoms include numbness, tingling, and pain. This study examines impact hammer vibration-induced injury and recoverability of hair mechanosensory innervation. Rat tails were vibrated 12 min/d for 5 weeks followed by 5 week recovery with synchronous non-vibrated controls. Nerve fibers were PGP9.5 immunostained. Lanceolate complex innervation was compared quantitatively in vibrated vs sham. Vibration peak acceleration magnitudes were characterized by frequency power spectral analysis. Average magnitude (2515 m/s2 , root mean squared) in kHz frequencies was 109 times that (23 m/s2 ) in low Hz. Percentage of hairs innervated by lanceolate complexes was 69.1% in 5-week sham and 53.4% in 5-week vibration generating a denervation difference of 15.7% higher in vibration. Hair innervation was 76.9% in 5-weeks recovery sham and 62.0% in 5-week recovery vibration producing a denervation difference 14.9% higher in recovery vibration. Lanceolate number per complex (18.4 ± 0.2) after vibration remained near sham (19.3 ± 0.3), but 44.9% of lanceolate complexes were abnormal in 5 weeks vibrated compared to 18.8% in sham. The largest vibration energies are peak kHz accelerations (approximately 100 000 m/s2 ) from shock waves. The existing ISO 5349-1 standard excludes kHz vibrations, seriously underestimating vibration injury risk. The present study validates the rat tail, impact hammer vibration as a model for investigating irreversible nerve damage. Persistence of higher denervation difference after 5-week recovery suggests repeated vibration injury destroys the capability of lanceolate nerve endings to regenerate.
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Affiliation(s)
- Jordan J Zimmerman
- Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - James L W Bain
- Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Chaowen Wu
- Plastic Surgery, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Hans Lindell
- Material Manufacturing, Swerea IVF, Mölndal, Sweden
| | | | - Danny A Riley
- Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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Krajnak K. Frequency-dependent changes in mitochondrial number and generation of reactive oxygen species in a rat model of vibration-induced injury. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2020; 83:20-35. [PMID: 31971087 PMCID: PMC7737659 DOI: 10.1080/15287394.2020.1718043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Regular use of vibrating hand tools results in cold-induced vasoconstriction, finger blanching, and a reduction in tactile sensitivity and manual dexterity. Depending upon the length and frequency, vibration induces regeneration, or dysfunction and apoptosis, inflammation and an increase in reactive oxygen species (ROS) levels. These changes may be associated with mitochondria, this study examined the effects of vibration on total and functional mitochondria number. Male rats were exposed to restraint or tail vibration at 62.5, 125, or 250 Hz. The frequency-dependent effects of vibration on mitochondrial number and generation of oxidative stress were examined. After 10 days of exposure at 125 Hz, ventral tail arteries (VTA) were constricted and there was an increase in mitochondrial number and intensity of ROS staining. In the skin, the influence of vibration on arterioles displayed a similar but insignificant response in VTA. There was also a reduction in the number of small nerves with exposure to vibration at 250 Hz, and a reduction in mitochondrial number in nerves in restrained and all vibrated conditions. There was a significant rise in the size of the sensory receptors with vibration at 125 Hz, and an elevation in ROS levels. Based upon these results, mitochondria number and activity are affected by vibration, especially at frequencies at or near resonance. The influence of vibration on the vascular system may either be adaptive or maladaptive. However, the effects on cutaneous nerves might be a precursor to loss of innervation and sensory function noted in workers exposed to vibration.
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Affiliation(s)
- Kristine Krajnak
- Physical Effects Research Branch, National Institute for Occupational Safety and Health, Morgantown, WV, USA
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Pacurari M, Waugh S, Krajnak K. Acute Vibration Induces Peripheral Nerve Sensitization in a Rat Tail Model: Possible Role of Oxidative Stress and Inflammation. Neuroscience 2018; 398:263-272. [PMID: 30553794 DOI: 10.1016/j.neuroscience.2018.12.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 12/05/2018] [Accepted: 12/06/2018] [Indexed: 12/20/2022]
Abstract
Prolonged occupational exposure to hand-held vibrating tools leads to pain and reductions in tactile sensitivity, grip strength and manual dexterity. The goal of the current study was to use a rat-tail vibration model to determine how vibration frequency influences factors related to nerve injury and dysfunction. Rats were exposed to restraint, or restraint plus tail vibration at 62.5 Hz or 250 Hz. Nerve function was assessed using the current perception threshold (CPT) test. Exposure to vibration at 62.5 and 250 Hz, resulted in a reduction in the CPT at 2000 and 250-Hz electrical stimulation (i.e. increased Aβ and Aδ, nerve fiber sensitivity). Vibration exposure at 250 Hz also resulted in an increased sensitivity of C-fibers to electrical stimulation and thermal nociception. These changes in nerve fiber sensitivity were associated with increased expression of interleukin (IL)-1β and tumor necrosis factor (TNF)-α in ventral tail nerves, and increases in circulating concentrations of IL-1 β in rats exposed to 250-Hz vibration. There was an increase in glutathione, but no changes in other measures of oxidative activity in the peripheral nerve. However, measures of oxidative stress were increased in the dorsal root ganglia (DRG). These changes in pro-inflammatory factors and markers of oxidative stress in the peripheral nerve and DRG were associated with inflammation, and reductions in myelin basic protein and post-synaptic density protein (PSD)-95 gene expression, suggesting that vibration-induced changes in sensory function may be the result of changes at the exposed nerve, the DRG and/or the spinal cord.
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Affiliation(s)
- M Pacurari
- Department of Biology, Jackson State University, Jackson, MS 39217, United States
| | - S Waugh
- Engineering and Controls Technology Branch, National Institute for Occupational Safety and Health, Morgantown, WV 26501, United States
| | - K Krajnak
- Engineering and Controls Technology Branch, National Institute for Occupational Safety and Health, Morgantown, WV 26501, United States.
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Krajnak K, Waugh S. Systemic Effects of Segmental Vibration in an Animal Model of Hand-Arm Vibration Syndrome. J Occup Environ Med 2018; 60:886-895. [PMID: 30020212 PMCID: PMC6173648 DOI: 10.1097/jom.0000000000001396] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
OBJECTIVE Epidemiology suggests that occupational exposure to hand-transmitted (segmental) vibration has local and systemic effects. This study used an animal model of segmental vibration to characterize the systemic effects of vibration. METHODS Male Sprague Dawley rats were exposed to tail vibration for 10 days. Genes indicative of inflammation, oxidative stress, and cell cycle, along were measured in the heart, kidney, prostate, and liver. RESULTS Vibration increased oxidative stress and pro-inflammatory gene expression, and decreased anti-oxidant enzymes in heart tissue. In the prostate and liver, vibration resulted in changes in the expression of pro-inflammatory factors and genes involved in cell cycle regulation. CONCLUSIONS These changes are consistent with epidemiological studies suggesting that segmental vibration has systemic effects. These effects may be mediated by changes in autonomic nervous system function, and/or inflammation and oxidative stress.
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Affiliation(s)
- Kristine Krajnak
- Engineering Controls and Technology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, Washington
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Krajnak K. Health effects associated with occupational exposure to hand-arm or whole body vibration. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2018; 21:320-334. [PMID: 30583715 PMCID: PMC6415671 DOI: 10.1080/10937404.2018.1557576] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Workers in a number of different occupational sectors are exposed to workplace vibration on a daily basis. This exposure may arise through the use of powered-hand tools or hand-transmitted vibration (HTV). Workers might also be exposed to whole body vibration (WBV) by driving delivery vehicles, earth moving equipment, or through use of tools that generate vibration at low dominant frequencies and high amplitudes, such as jackhammers. Occupational exposure to vibration has been associated with an increased risk of musculoskeletal pain in the back, neck, hands, shoulders, and hips. Occupational exposure may also contribute to the development of peripheral and cardiovascular disorders and gastrointestinal problems. In addition, there are more recent data suggesting that occupational exposure to vibration may enhance the risk of developing certain cancers. The aim of this review is to provide an assessment of the occupations where exposure to vibration is most prevalent, and a description of the adverse health effects associated with occupational exposure to vibration. This review will examine (1) various experimental methods used to measure and describe the characteristics of vibration generated by various tools and vehicles, (2) the etiology of vibration-induced disorders, and (3) how these data were employed to assess and improve intervention strategies and equipment that reduces the transmission of vibration to the body. Finally, there is a discussion of the research gaps that need to be investigated to further reduction in the incidence of vibration-induced illnesses and injuries.
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Affiliation(s)
- Kristine Krajnak
- a Health Effects Laboratory Division , National Institute for Occupational Safety and Health , Morgantown , WV , USA
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Krajnak K, Miller GR, Waugh S. Contact area affects frequency-dependent responses to vibration in the peripheral vascular and sensorineural systems. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2018; 81:6-19. [PMID: 29173119 PMCID: PMC6379067 DOI: 10.1080/15287394.2017.1401022] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 11/01/2017] [Indexed: 05/18/2023]
Abstract
Repetitive exposure to hand-transmitted vibration is associated with development of peripheral vascular and sensorineural dysfunctions. These disorders and symptoms associated with it are referred to as hand-arm vibration syndrome (HAVS). Although the symptoms of the disorder have been well characterized, the etiology and contribution of various exposure factors to development of the dysfunctions are not well understood. Previous studies performed using a rat-tail model of vibration demonstrated that vascular and peripheral nervous system adverse effects of vibration are frequency-dependent, with vibration frequencies at or near the resonant frequency producing the most severe injury. However, in these investigations, the amplitude of the exposed tissue was greater than amplitude typically noted in human fingers. To determine how contact with vibrating source and amplitude of the biodynamic response of the tissue affects the risk of injury occurring, this study compared the influence of frequency using different levels of restraint to assess how maintaining contact of the tail with vibrating source affects the transmission of vibration. Data demonstrated that for the most part, increasing the contact of the tail with the platform by restraining it with additional straps resulted in an enhancement in transmission of vibration signal and elevation in factors associated with vascular and peripheral nerve injury. In addition, there were also frequency-dependent effects, with exposure at 250 Hz generating greater effects than vibration at 62.5 Hz. These observations are consistent with studies in humans demonstrating that greater contact and exposure to frequencies near the resonant frequency pose the highest risk for generating peripheral vascular and sensorineural dysfunction.
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Affiliation(s)
- Kristine Krajnak
- a Engineering and Controls Technology Branch , National Institute for Occupational Safety and Health Morgantown , Morgantown , WV , USA
| | - G R Miller
- a Engineering and Controls Technology Branch , National Institute for Occupational Safety and Health Morgantown , Morgantown , WV , USA
| | - Stacey Waugh
- a Engineering and Controls Technology Branch , National Institute for Occupational Safety and Health Morgantown , Morgantown , WV , USA
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Waugh S, Kashon ML, Li S, Miller GR, Johnson C, Krajnak K. Transcriptional Pathways Altered in Response to Vibration in a Model of Hand-Arm Vibration Syndrome. J Occup Environ Med 2016; 58:344-50. [PMID: 27058473 PMCID: PMC4837947 DOI: 10.1097/jom.0000000000000705] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE The aim of this study was to use an established model of vibration-induced injury to assess frequency-dependent changes in transcript expression in skin, artery, and nerve tissues. METHODS Transcript expression in tissues from control and vibration-exposed rats (4 h/day for 10 days at 62.5, 125, or 250 Hz; 49 m/s, rms) was measured. Transcripts affected by vibration were used in bioinformatics analyses to identify molecular- and disease-related pathways associated with exposure to vibration. RESULTS Analyses revealed that cancer-related pathways showed frequency-dependent changes in activation or inhibition. Most notably, the breast-related cancer-1 pathway was affected. Other pathways associated with breast cancer type 1 susceptibility protein related signaling, or associated with cancer and cell cycle/cell survivability were also affected. CONCLUSION Occupational exposure to vibration may result in DNA damage and alterations in cell signaling pathways that have significant effects on cellular division.
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Affiliation(s)
- Stacey Waugh
- Engineering Controls and Technology Branch and Biostatistics and Epidemiology Branch (Waugh, Miller, Johnson, Dr Krajnak), and National Institute for Occupational Safety and Health, Morgantown, West Virginia (Drs Kashon, Li)
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Krajnak K, Raju SG, Miller GR, Johnson C, Waugh S, Kashon ML, Riley DA. Long-term daily vibration exposure alters current perception threshold (CPT) sensitivity and myelinated axons in a rat-tail model of vibration-induced injury. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2016; 79:101-111. [PMID: 26852665 DOI: 10.1080/15287394.2015.1104272] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Repeated exposure to hand-transmitted vibration through the use of powered hand tools may result in pain and progressive reductions in tactile sensitivity. The goal of the present study was to use an established animal model of vibration-induced injury to characterize changes in sensory nerve function and cellular mechanisms associated with these alterations. Sensory nerve function was assessed weekly using the current perception threshold test and tail-flick analgesia test in male Sprague-Dawley rats exposed to 28 d of tail vibration. After 28 d of exposure, Aβ fiber sensitivity was reduced. This reduction in sensitivity was partly attributed to structural disruption of myelin. In addition, the decrease in sensitivity was also associated with a reduction in myelin basic protein and 2',3'- cyclic nucleotide phosphodiasterase (CNPase) staining in tail nerves, and an increase in circulating calcitonin gene-related peptide (CGRP) concentrations. Changes in Aβ fiber sensitivity and CGRP concentrations may serve as early markers of vibration-induced injury in peripheral nerves. It is conceivable that these markers may be utilized to monitor sensorineural alterations in workers exposed to vibration to potentially prevent additional injury.
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Affiliation(s)
- Kristine Krajnak
- a Engineering and Control Technology Branch, Health Effects Laboratory Division , National Institute for Occupational Safety and Health , Morgantown , West Virginia , USA
| | - Sandya G Raju
- b Department of Cell Biology, Neurobiology & Anatomy , Medical College of Wisconsin , Milwaukee , Wisconsin , USA
| | - G Roger Miller
- a Engineering and Control Technology Branch, Health Effects Laboratory Division , National Institute for Occupational Safety and Health , Morgantown , West Virginia , USA
| | - Claud Johnson
- a Engineering and Control Technology Branch, Health Effects Laboratory Division , National Institute for Occupational Safety and Health , Morgantown , West Virginia , USA
| | - Stacey Waugh
- a Engineering and Control Technology Branch, Health Effects Laboratory Division , National Institute for Occupational Safety and Health , Morgantown , West Virginia , USA
| | - Michael L Kashon
- c Biostatistics and Epidemiology Branch, Health Effects Laboratory Division , National Institute for Occupational Safety and Health , Morgantown , West Virginia , USA
| | - Danny A Riley
- b Department of Cell Biology, Neurobiology & Anatomy , Medical College of Wisconsin , Milwaukee , Wisconsin , USA
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Kiedrowski M, Waugh S, Miller R, Johnson C, Krajnak K. The effects of repetitive vibration on sensorineural function: biomarkers of sensorineural injury in an animal model of metabolic syndrome. Brain Res 2015; 1627:216-24. [PMID: 26433044 DOI: 10.1016/j.brainres.2015.09.026] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 09/14/2015] [Accepted: 09/22/2015] [Indexed: 10/23/2022]
Abstract
Exposure to hand-transmitted vibration in the work-place can result in the loss of sensation and pain in workers. These effects may be exacerbated by pre-existing conditions such as diabetes or the presence of primary Raynaud's phenomena. The goal of these studies was to use an established model of vibration-induced injury in Zucker rats. Lean Zucker rats have a normal metabolic profile, while obese Zucker rats display symptoms of metabolic disorder or Type II diabetes. This study examined the effects of vibration in obese and lean rats. Zucker rats were exposed to 4h of vibration for 10 consecutive days at a frequency of 125 Hz and acceleration of 49 m/s(2) for 10 consecutive days. Sensory function was checked using transcutaneous electrical stimulation on days 1, 5 and 9 of the exposure. Once the study was complete the ventral tail nerves, dorsal root ganglia and spinal cord were dissected, and levels of various transcripts involved in sensorineural dysfunction were measured. Sensorineural dysfunction was assessed using transcutaneous electrical stimulation. Obese Zucker rats displayed very few changes in sensorineural function. However they did display significant changes in transcript levels for factors involved in synapse formation, peripheral nerve remodeling, and inflammation. The changes in transcript levels suggested that obese Zucker rats had some level of sensory nerve injury prior to exposure, and that exposure to vibration activated pathways involved in injury and re-innervation.
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Affiliation(s)
- Megan Kiedrowski
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA
| | - Stacey Waugh
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA
| | - Roger Miller
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA
| | - Claud Johnson
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA
| | - Kristine Krajnak
- National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA.
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Eger T, Thompson A, Leduc M, Krajnak K, Goggins K, Godwin A, House R. Vibration induced white-feet: overview and field study of vibration exposure and reported symptoms in workers. Work 2015; 47:101-10. [PMID: 24004754 DOI: 10.3233/wor-131692] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Workers who stand on platforms or equipment that vibrate are exposed to foot-transmitted vibration (FTV). Exposure to FTV can lead to vibration white feet/toes resulting in blanching of the toes, and tingling and numbness in the feet and toes. OBJECTIVES The objectives are 1) to review the current state of knowledge of the health risks associated with foot-transmitted vibration (FTV), and 2) to identify the characteristics of FTV and discuss the associated risk of vibration-induced injury. PARTICIPANTS Workers who operated locomotives (n=3), bolting platforms (n=10), jumbo drills (n=7), raise drilling platforms (n=4), and crushers (n=3), participated. METHODS A tri-axial accelerometer was used to measure FTV in accordance with ISO 2631-1 guidelines. Frequency-weighted root-mean-square acceleration and the dominant frequency are reported. Participants were also asked to report pain/ache/discomfort in the hands and/or feet. RESULTS Reports of pain/discomfort/ache were highest in raise platform workers and jumbo drill operators who were exposed to FTV in the 40 Hz and 28 Hz range respectively. Reports of discomfort/ache/pain were lowest in the locomotive and crusher operators who were exposed to FTV below 10 Hz. These findings are consistent with animal studies that have shown vascular and neural damage in exposed appendages occurs at frequencies above 40 Hz. CONCLUSIONS Operators exposed to FTV at 40 Hz appear to be at greater risk of experiencing vibration induced injury. Future research is required to document the characteristics of FTV and epidemiological evidence is required to link exposure with injury.
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Affiliation(s)
- Tammy Eger
- School of Human Kinetics, Laurentian University, Sudbury, ON, Canada Centre for Research in Occupational Safety and Health, Laurentian University, Sudbury, ON, Canada
| | - Aaron Thompson
- Department of Medicine, Division of Occupational Medicine, University of Toronto, Toronto, ON, Canada Department of Occupational and Environmental Health, St. Michael's Hospital, Toronto, ON, Canada
| | - Mallorie Leduc
- School of Human Kinetics, Laurentian University, Sudbury, ON, Canada
| | - Kristine Krajnak
- Engineering and Controls Technology Branch, National Institute for Occupational Safety and Health, Morgantown, WV, USA
| | - Katie Goggins
- School of Human Kinetics, Laurentian University, Sudbury, ON, Canada
| | - Alison Godwin
- School of Human Kinetics, Laurentian University, Sudbury, ON, Canada Centre for Research in Occupational Safety and Health, Laurentian University, Sudbury, ON, Canada
| | - Ron House
- Department of Medicine, Division of Occupational Medicine, University of Toronto, Toronto, ON, Canada Department of Occupational and Environmental Health, St. Michael's Hospital, Toronto, ON, Canada
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17
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PEELUKHANA SV, GOENKA S, KIM B, KIM J, BHATTACHARYA A, STRINGER KF, BANERJEE RK. Effect of higher frequency components and duration of vibration on bone tissue alterations in the rat-tail model. INDUSTRIAL HEALTH 2015; 53:245-259. [PMID: 25843564 PMCID: PMC4466877 DOI: 10.2486/indhealth.2014-0117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2014] [Accepted: 01/29/2015] [Indexed: 06/04/2023]
Abstract
To formulate more accurate guidelines for musculoskeletal disorders (MSD) linked to Hand-Arm Vibration Syndrome (HAVS), delineation of the response of bone tissue under different frequencies and duration of vibration needs elucidation. Rat-tails were vibrated at 125 Hz (9 rats) and 250 Hz (9 rats), at 49 m/s(2), for 1D (6 rats), 5D (6 rats) and 20D (6 rats); D=days (4 h/d). Rats in the control group (6 rats for the vibration groups; 2 each for 1D, 5D, and 20D) were left in their cages, without being subjected to any vibration. Structural and biochemical damages were quantified using empty lacunae count and nitrotyrosine signal-intensity, respectively. One-way repeated-measure mixed-model ANOVA at p<0.05 level of significance was used for analysis. In the cortical bone, structural damage quantified through empty lacunae count was significant (p<0.05) at 250 Hz (10.82 ± 0.66) in comparison to the control group (7.41 ± 0.76). The biochemical damage was significant (p<0.05) at both the 125 Hz and 250 Hz vibration frequencies. The structural damage was significant (p<0.05) at 5D for cortical bone while the trabecular bone showed significant (p<0.05) damage at 20D time point. Further, the biochemical damage increased with increase in the duration of vibration with a significant (p<0.05) damage observed at 20D time point and a near significant change (p=0.08) observed at 5D time point. Structural and biochemical changes in bone tissue are dependent upon higher vibration frequencies of 125 Hz, 250 Hz and the duration of vibration (5D, 20D).
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Affiliation(s)
| | - Shilpi GOENKA
- Department of Mechanical and Materials Engineering,
University of Cincinnati, USA
| | - Brian KIM
- Department of Mechanical and Materials Engineering,
University of Cincinnati, USA
| | - Jay KIM
- Department of Mechanical and Materials Engineering,
University of Cincinnati, USA
| | | | - Keith F. STRINGER
- Department of Pathology, Cincinnati Children’s Hospital
Medical Centre, USA
| | - Rupak K. BANERJEE
- Department of Mechanical and Materials Engineering,
University of Cincinnati, USA
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Krajnak K, Waugh S, Johnson C, Miller RG, Welcome D, Xu X, Warren C, Sarkisian S, Andrew M, Dong RG. Antivibration gloves: effects on vascular and sensorineural function, an animal model. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2015; 78:571-82. [PMID: 25965192 PMCID: PMC4700820 DOI: 10.1080/15287394.2015.1014079] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Anti-vibration gloves have been used to block the transmission of vibration from powered hand tools to the user, and to protect users from the negative health consequences associated with exposure to vibration. However, there are conflicting reports as to the efficacy of gloves in protecting workers. The goal of this study was to use a characterized animal model of vibration-induced peripheral vascular and nerve injury to determine whether antivibration materials reduced or inhibited the effects of vibration on these physiological symptoms. Rats were exposed to 4 h of tail vibration at 125 Hz with an acceleration 49 m/s(2). The platform was either bare or covered with antivibrating glove material. Rats were tested for tactile sensitivity to applied pressure before and after vibration exposure. One day following the exposure, ventral tail arteries were assessed for sensitivity to vasodilating and vasoconstricting factors and nerves were examined histologically for early indicators of edema and inflammation. Ventral tail artery responses to an α2C-adrenoreceptor agonist were enhanced in arteries from vibration-exposed rats compared to controls, regardless of whether antivibration materials were used or not. Rats exposed to vibration were also less sensitive to pressure after exposure. These findings are consistent with experimental findings in humans suggesting that antivibration gloves may not provide protection against the adverse health consequences of vibration exposure in all conditions. Additional studies need to be done examining newer antivibration materials.
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Affiliation(s)
- K Krajnak
- a Engineering and Controls Technology Branch , National Institute for Occupational Safety and Health , Morgantown , West Virginia , USA
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19
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Krajnak K, Waugh S, Miller GR, Johnson C. Recovery of vascular function after exposure to a single bout of segmental vibration. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2014; 77:1061-9. [PMID: 25072825 PMCID: PMC4505626 DOI: 10.1080/15287394.2014.903813] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Work rotation schedules may be used to reduce the negative effects of vibration on vascular function. This study determined how long it takes vascular function to recover after a single exposure to vibration in rats (125 Hz, acceleration 5 g). The responsiveness of rat-tail arteries to the vasoconstricting factor UK14304, an α2C-adrenoreceptor agonist, and the vasodilating factor acetylcholine (ACh) were measured ex vivo 1, 2, 7, or 9 d after exposure to a single bout of vibration. Vasoconstriction induced by UK14304 returned to control levels after 1 d of recovery. However, re-dilation induced by ACh did not return to baseline until after 9 d of recovery. Exposure to vibration exerted prolonged effects on peripheral vascular function, and altered vascular responses to a subsequent exposure. To optimize the positive results of work rotation schedules, it is suggested that studies assessing recovery of vascular function after exposure to a single bout of vibration be performed in humans.
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Affiliation(s)
- Kristine Krajnak
- a Engineering and Controls Technology Branch , Health Effects Laboratory Division, National Institute for Occupational Safety and Health , Morgantown , West Virginia , USA
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20
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KRAJNAK KM, WAUGH S, JOHNSON C, MILLER GR, XU X, WARREN C, DONG RG. The effects of impact vibration on peripheral blood vessels and nerves. INDUSTRIAL HEALTH 2013; 51:572-80. [PMID: 24077447 PMCID: PMC4202742 DOI: 10.2486/indhealth.2012-0193] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Accepted: 07/30/2013] [Indexed: 05/03/2023]
Abstract
Research regarding the risk of developing hand-arm vibration syndrome after exposure to impact vibration has produced conflicting results. This study used an established animal model of vibration-induced dysfunction to determine how exposure to impact vibration affects peripheral blood vessels and nerves. The tails of male rats were exposed to a single bout of impact vibration (15 min exposure, at a dominant frequency of 30 Hz and an unweighted acceleration of approximately 345 m/s(2)) generated by a riveting hammer. Responsiveness of the ventral tail artery to adrenoreceptor-mediated vasoconstriction and acetylcholine-mediated re-dilation was measured ex vivo. Ventral tail nerves and nerve endings in the skin were assessed using morphological and immunohistochemical techniques. Impact vibration did not alter vascular responsiveness to any factors or affect trunk nerves. However, 4 days following exposure there was an increase in protein-gene product (PGP) 9.5 staining around hair follicles. A single exposure to impact vibration, with the exposure characteristics described above, affects peripheral nerves but not blood vessels.
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Affiliation(s)
- Kristine M. KRAJNAK
- Engineering and Controls Technology Branch, National
Institutes for Occupational Safety and Health, USA
| | - Stacey WAUGH
- Engineering and Controls Technology Branch, National
Institutes for Occupational Safety and Health, USA
| | - Claud JOHNSON
- Engineering and Controls Technology Branch, National
Institutes for Occupational Safety and Health, USA
| | - G. Roger MILLER
- Engineering and Controls Technology Branch, National
Institutes for Occupational Safety and Health, USA
| | - Xueyan XU
- Engineering and Controls Technology Branch, National
Institutes for Occupational Safety and Health, USA
| | - Christopher WARREN
- Engineering and Controls Technology Branch, National
Institutes for Occupational Safety and Health, USA
| | - Ren G. DONG
- Engineering and Controls Technology Branch, National
Institutes for Occupational Safety and Health, USA
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21
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Goenka S, Peelukhana SV, Kim J, Stringer KF, Banerjee RK. Dependence of vascular damage on higher frequency components in the rat-tail model. INDUSTRIAL HEALTH 2013; 51:373-385. [PMID: 23518603 DOI: 10.2486/indhealth.2012-0060] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Hand-Arm Vibration Syndrome (HAVS) is caused by hand-transmitted vibration in industrial workers. Current ISO guidelines (ISO 5349) might underestimate vascular injury associated with range of vibration frequencies near resonance. A rat-tail model was used to investigate the effects of higher frequencies >100 Hz on early vascular damage. 13 Male Sprague-Dawley rats (250 ± 15 gm) were used. Rat-tails were vibrated at 125 Hz and 250 Hz (49 m/s(2)) for 1D, 5D and 10D; D=days (4 h/day). Structural damage of the ventral artery was quantified by vacuole count using Toluidine blue staining whereas biochemical changes were assessed by nitrotyrosine (NT) staining. The results were analyzed using one-way repeated measures mixed-model ANOVA at p<0.05 level of significance. The structural damage increased at 125 Hz causing significant number of vacuoles (40.62 ± 9.8) compared to control group (8.36 ± 2.49) and reduced at 250 Hz (12.33 ± 2.98) compared to control group (8.36 ± 2.49). However, the biochemical alterations (NT-signal) increased significantly for 125 Hz (143.35 ± 5.8 gray scale value, GSV) and for 250 Hz (155.8 ± 7.35 GSV) compared to the control group (101.7 ± 4.18 GSV). Our results demonstrate that vascular damage in the form of structural and bio chemical disruption is significant at 125 Hz and 250 Hz. Hence the current ISO guidelines might underestimate vascular damage at frequencies>100 Hz.
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Affiliation(s)
- Shilpi Goenka
- School of Energy, Environmental, Biological and Medical Engineering, Materials Engineering Program, University of Cincinnati, USA
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22
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Characterization of frequency-dependent responses of the vascular system to repetitive vibration. J Occup Environ Med 2013; 54:1010-6. [PMID: 22785326 DOI: 10.1097/jom.0b013e318255ba74] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
OBJECTIVE Occupational exposure to hand-transmitted vibration can result in damage to nerves and sensory loss. The goal of this study was to assess the frequency-dependent effects of repeated bouts of vibration on sensory nerve function and associated changes in nerves. METHODS The tails of rats were exposed to vibration at 62.5, 125, or 250 Hz (constant acceleration of 49 m/s2) for 10 days. The effects on sensory nerve function, nerve morphology, and transcript expression in ventral tail nerves were measured. RESULTS Vibration at all frequencies had effects on nerve function and physiology. However, the effects tended to be more prominent with exposure at 250 Hz. CONCLUSION Exposure to vibration has detrimental effects on sensory nerve function and physiology. However, many of these changes are more prominent at 250-Hz exposure than at lower frequencies.
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Characterization of Frequency-Dependent Responses of the Vascular System to Repetitive Vibration. J Occup Environ Med 2010; 52:584-94. [DOI: 10.1097/jom.0b013e3181e12b1f] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Krajnak K, Waugh S, Johnson C, Miller R, Kiedrowski M. Vibration disrupts vascular function in a model of metabolic syndrome. INDUSTRIAL HEALTH 2009; 47:533-542. [PMID: 19834263 DOI: 10.2486/indhealth.47.533] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Vibration-induced white finger (VWF) is a disorder seen in workers exposed to hand-transmitted vibration, and is characterized by cold-induced vasospasms and finger blanching. Because overweight people with metabolic syndrome are pre-disposed to developing peripheral vascular disorders, it has been suggested that they also may be at greater risk of developing VWF if exposed to occupational vibration. We used an animal model of metabolic syndrome, the obese Zucker rat, to determine if metabolic syndrome alters vascular responses to vibration. Tails of lean and obese Zucker rats were exposed to vibration (125 Hz, 49 m/s(2) r.m.s.) or control conditions for 4 h/d for 10 d. Ventral tail arteries were collected and assessed for changes in gene expression, levels of reactive oxygen species (ROS) and for responsiveness to vasomodulating factors. Vibration exposure generally reduced the sensitivity of arteries to acetylcholine (ACh)-induced vasodilation. This decrease in sensitivity was most apparent in obese rats. Vibration also induced reductions in vascular nitric oxide concentrations and increases in vascular concentrations of ROS in obese rats. These results indicate that vibration interferes with endothelial-mediated vasodilation, and that metabolic syndrome exacerbates these effects. These findings are consistent with idea that workers with metabolic syndrome have an increased risk of developing VWF.
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Affiliation(s)
- Kristine Krajnak
- Engineering and Controls Technology Branch, National Institute for Occupational Safety and Health, 1095 Willowdale Rd, Morgantown, WV 26505, USA.
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Hughes JM, Wirth O, Krajnak K, Miller R, Flavahan S, Berkowitz DE, Welcome D, Flavahan NA. Increased oxidant activity mediates vascular dysfunction in vibration injury. J Pharmacol Exp Ther 2008; 328:223-30. [PMID: 18955588 DOI: 10.1124/jpet.108.144618] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Occupational exposure to hand-operated vibrating tools causes a spectrum of pathological changes in the vascular, neurological, and musculoskeletal systems described as the hand-arm vibration syndrome (HAVS). Experiments were performed to determine the effects of acute vibration on the function of digital arteries. Rats paws were exposed to a vibrating platform (4 h, 125 Hz, constant acceleration of 49 m/s(2) root mean squared), and digital artery function was assessed subsequently in vitro using a pressure myograph system. Constriction to phenylephrine or 5-hydroxytryptamine was reduced in digital arteries from vibrated paws. However, after endothelium denudation, constriction to the agonists was no longer impaired in vibrated arteries. Inhibition of nitric-oxide synthase (NOS) with N(omega)-nitro-l-arginine methyl ester (l-NAME) increased constriction to phenylephrine or 5-hydroxytryptamine in vibrated but not control arteries and abolished the vibration-induced depression in constrictor responses. However, nitric oxide (NO) activity, determined using the NO-sensitive probe 4-amino-5-methylamino-2', 7'-difluorofluorescein, was reduced in vibrated compared with control arteries. Endogenous levels of reactive oxygen species (ROS), determined using the ROS-sensitive probe 5-(and 6)-chloromethyl-2',7'-dichlorodihydro-fluorescein, were increased in vibrated compared with control arteries. The increased ROS levels were abolished by L-NAME or by catalase, which degrades extracellular hydrogen peroxide. Catalase also increased constriction to phenylephrine or 5-hydroxytryptamine in vibrated but not control arteries and abolished the vibration-induced depression in constrictor responses. The results suggest that acute vibration causes vascular dysfunction in digital arteries by increasing ROS levels, which is probably mediated by uncoupling of endothelial NOS. Therefore, therapeutic strategies to inhibit ROS or augment NO activity may be beneficial in HAVS.
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Affiliation(s)
- Jennifer M Hughes
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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