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Maldonado CJ, White-Phillip JA, Liu Y, Erbele ID, Choi YS. Exposomic Signatures of Tinnitus and/or Hearing Loss. Mil Med 2023; 188:102-109. [PMID: 37948208 DOI: 10.1093/milmed/usad046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 01/24/2023] [Accepted: 02/08/2023] [Indexed: 11/12/2023] Open
Abstract
INTRODUCTION We evaluated the risk factors associated with tinnitus and/or hearing loss (THL) among active duty (AD) members of the U.S. Army and Marine Aviation Community (AMAC) using an exposomic approach. Specifically, we aimed to determine the factors associated with the reported THL in the Military Health System. METHODS Longitudinal data were obtained from the Medical Assessment and Readiness System housed at Womack Army Medical Center, Fort Bragg, NC, for a retrospective cohort study that included 78,546 AD AMAC members from October 2015 to December 2019. Multivariable mixed-effects logistic regression was used to assess the relationship between THL and numerous variables to include rank, service time, deployment, tobacco use, alcohol use, age, gender, race, ethnicity, and body mass index. RESULTS Our analysis included a total of 220,044 person-years of observations. The THL incidence rate was 6.7 per 100 person-years, with an 8.1% period prevalence. THL was associated with age, gender, body mass index, race, deployment, service time, marital status, and tobacco use (all P < .05). Service time greater than 16 years had the greatest odds ratio of THL (4.46, 95% CI: 3.58-5.55, P < .001). CONCLUSIONS Our assessment shows the utility of using an exposomic approach to create member-specific personalized clinical algorithms for health outcomes. We examined individuals with THL diagnoses and identified a combination of risk factors from biomedical, lifestyle, environmental, and stochastic sources. Taken together, the risk factors identified across the four exposomic domains could help understand the etiology of THL. Our exposomic methodology could be the foundation for generating predictive models. Finally, a specific evaluation of occupational risk factors may provide insight into aspects not readily available from civilian literature. In upcoming years, as the Medical Assessment and Readiness System matures, we will expand our analyses to include prospective, untargeted metabolites and biomarker data.
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Affiliation(s)
- Carlos J Maldonado
- Department of Clinical Investigation, Womack Army Medical Center, Fort Bragg, NC 28310, USA
| | | | - Yuliang Liu
- Department of Veterans Affairs, Veterans Administration Central Office, Washington, DC 20420, USA
| | - Isaac D Erbele
- Department of Otolaryngology, Brooke Army Medical Center, JBSA Fort Sam Houston, TX 78234, USA
| | - Y Sammy Choi
- Department of Clinical Investigation, Womack Army Medical Center, Fort Bragg, NC 28310, USA
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Sterner TR, Covington TR, Mattie DR. Complex Mixtures: Array PBPK Modeling of Jet Fuel Components. TOXICS 2023; 11:187. [PMID: 36851061 PMCID: PMC9964161 DOI: 10.3390/toxics11020187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/12/2023] [Accepted: 02/14/2023] [Indexed: 06/18/2023]
Abstract
An array physiologically-based pharmacokinetic (PBPK) model represents a streamlined method to simultaneously quantify dosimetry of multiple compounds. To predict internal dosimetry of jet fuel components simultaneously, an array PBPK model was coded to simulate inhalation exposures to one or more selected compounds: toluene, ethylbenzene, xylenes, n-nonane, n-decane, and naphthalene. The model structure accounts for metabolism of compounds in the lung and liver, as well as kinetics of each compound in multiple tissues, including the cochlea and brain regions associated with auditory signaling (brainstem and temporal lobe). The model can accommodate either diffusion-limited or flow-limited kinetics (or a combination), allowing the same structure to be utilized for compounds with different characteristics. The resulting model satisfactorily simulated blood concentration and tissue dosimetry data from multiple published single chemical rat studies. The model was then utilized to predict tissue kinetics for the jet fuel hearing loss study (JTEH A, 25:1-14). The model was also used to predict rat kinetic comparisons between hypothetical exposures to JP-8 or a Virent Synthesized Aromatic Kerosene (SAK):JP-8 50:50 blend at the occupational exposure limit (200 mg/m3). The array model has proven useful for comparing potential tissue burdens resulting from complex mixture exposures.
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Affiliation(s)
- Teresa R. Sterner
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Wright-Patterson Air Force Base, Dayton, OH 45433, USA
- Air Force Research Laboratory, 711HPW/RHBAF, Wright-Patterson Air Force Base, Dayton, OH 45433, USA
| | - Tammie R. Covington
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Wright-Patterson Air Force Base, Dayton, OH 45433, USA
- Air Force Research Laboratory, 711HPW/RHBAF, Wright-Patterson Air Force Base, Dayton, OH 45433, USA
| | - David R. Mattie
- Air Force Research Laboratory, 711HPW/RHBAF, Wright-Patterson Air Force Base, Dayton, OH 45433, USA
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Guthrie OW. Abnormal neural adaptation consequent to combined exposure to jet fuel and noise. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2022; 85:671-684. [PMID: 35469543 DOI: 10.1080/15287394.2022.2069064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A fundamental property of first-order sensory neurons is the ability to alter their response properties as a function of change in the statistical parameters of an input signal. Such neural adaptation shapes the performance features of contiguous neural circuits that ultimately drive sensory discrimination. The current study focused on whether combined exposure to jet fuel and noise might alter the capacity of the auditory nerve to adapt to stimulus presentation speed. Young hooded Long-Evans 4-5 weeks old male rats were grouped and used in the current experiment. One group was exposed via inhalation to 1000 mg/m3 of jet propulsion fuel for 6 hr per day, 5 days per week for 4 weeks. Another group was exposed to a 5.5-11.3 kHz band-pass noise at 85 dB SPL for 6 hr per day, 5 days per week for 4 weeks. An additional group was simultaneously exposed to both jet fuel and noise. An age-matched group served as control and was not exposed to either jet fuel or noise. After experimental exposures, animals were given 4 weeks to recover and then assessed for neural adaptation. Both slow and fast rectangular voltage pulses were employed to elicit neuroelectric activity from the animals. Data demonstrated significant neural adaptation (1.46 μV shift) among controls, where neural activity decreased as the stimulus presentation speed rose from 10 to 100 per sec. This effect might also be observed in animals in the jet fuel treated and rats in the noise-exposed group. However, animals who were simultaneously exposed to both jet fuel and noise failed to exhibit neural adaptation. This abnormality appeared to be masked because independent slow and fast stimuli produced similar neural activity between controls and rats exposed to both jet fuel and noise. Therefore, neural adaptation assays may further be developed to unmask silent neurotoxicity consequent to physiochemical exposures.
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Affiliation(s)
- O'Neil W Guthrie
- Cell & Molecular Pathology Laboratory, Communication Sciences and Disorders, Northern Arizona University, Flagstaff, AZ, USA
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Guthrie OW, Wong BA, McInturf SM, Mattie DR. Degenerate brainstem circuitry after combined physiochemical exposure to jet fuel and noise. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2022; 85:175-183. [PMID: 34913848 DOI: 10.1080/15287394.2021.1980166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Degenerate neural circuits exhibit "different" circuit properties yet produce similar circuit outcomes (many-to-one) which ensures circuit robustness and complexity. However, neuropathies may hijack degeneracy to yield robust and complex pathological circuits. The aim of the current study was to test the hypothesis that physiochemical exposure to combined jet fuel and noise might induce degeneracy in the brainstem. The auditory brainstem of pigmented rats was used as a model system. The animals were randomized into the following experimental groups: Fuel+Noise, fuel-only, noise-only, and control. Ascending volume conductance from various auditory brainstem regions were evaluated simultaneously with peripheral nervous system (PNS) input to brainstem circuitry. Data demonstrated normal PNS inputs for all groups. However, the Fuel+Noise exposure group produced different caudal brainstem circuit properties while rostral brainstem circuitry initiated outputs that were similar to that of control. This degenerative effect was specific to Fuel+Noise exposure, since neither noise-alone or fuel-alone produced the same result. Degeneracy in the auditory brainstem is consistent with perceptual abnormalities, such as poor speech discrimination (hear but not understand), tinnitus (ringing in the ear), hyperacusis (hypersensitivity to even low-level sound), and loudness intolerance. Therefore, a potential consequence of Fuel+Noise exposure among military and civilian populations may be evidenced as increased rates of super-threshold auditory perceptual abnormalities. This is particularly important because to date, the ototoxic profile of Fuel+Noise exposure has remained unresolved.
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Affiliation(s)
- O'neil W Guthrie
- Cell & Molecular Pathology Laboratory, Communication Sciences and Disorders, Northern Arizona University, Flagstaff, AZ, USA
| | - Brian A Wong
- Naval Medical Research Unit Dayton, Wright-Patterson Air Force Base, OH, USA
- Oak Ridge Institute for Science and Education (Orise), Oak Ridge, TN, USA
| | - Shawn M McInturf
- Naval Medical Research Unit Dayton, Wright-Patterson Air Force Base, OH, USA
| | - David R Mattie
- 711 Human Performance Wing, Wright-Patterson Air Force Base, OH, USA
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Dreisbach L, Murphy S, Arevalo R, Schlocker C, Miller T, Guthrie OW. Is jet fuel exposure associated with central auditory nervous system difficulties: An exploratory study in military personnel. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2022; 151:2027. [PMID: 35364904 DOI: 10.1121/10.0009845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 03/04/2022] [Indexed: 06/14/2023]
Abstract
Central auditory nervous system dysfunction (CANSD) can manifest as hearing difficulty in the absence of audiometric abnormalities. Effects of noise or jet fuel exposure on the CANS are documented in animal models and humans. This study screened military personnel using the modified Amsterdam Inventory for Auditory Disability (mAIAD) to assess whether concurrent jet fuel and noise (JFN) exposures potentiate central auditory difficulties compared to noise only exposures. A total of 48 age- and sex-matched participants were recruited: 24 military bulk fuel specialists (JFN) and 24 military personnel without jet fuel exposure. All participants completed the mAIAD, the Noise Exposure Questionnaire, and basic audiological testing. Results revealed non-significant differences in pure-tone thresholds between groups, but the JFN group had higher noise exposures. Additionally, the JFN group revealed consistently lower mAIAD scores compared to the noise only group. Interestingly, a JFN stratified subgroup reporting more listening difficulty exhibited statistically significant lower mAIAD scores in the speech intelligibility in noise subdomain. These preliminary data suggest that jet fuel exposure may potentiate noise-induced CANSD, such as speech-in-noise difficulties. Such difficulties may be more prominent among specific military personnel with combined exposures. Hearing conservation programs could add CANSD screening by use of the mAIAD.
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Affiliation(s)
- Laura Dreisbach
- School of Speech, Language and Hearing Sciences, San Diego State University, 5500 Campanile Drive, San Diego, California 92182-1518, USA
| | - Sara Murphy
- Navy Medicine Readiness and Training Command San Diego (NMRTC SD), 34800 Bob Wilson Drive, San Diego, California 92134, USA
| | - Reginald Arevalo
- School of Speech, Language and Hearing Sciences, San Diego State University, 5500 Campanile Drive, San Diego, California 92182-1518, USA
| | - Caroline Schlocker
- Navy Medicine Readiness and Training Command San Diego (NMRTC SD), 34800 Bob Wilson Drive, San Diego, California 92134, USA
| | - Tanner Miller
- Navy Medicine Readiness and Training Command San Diego (NMRTC SD), 34800 Bob Wilson Drive, San Diego, California 92134, USA
| | - O'neil Winston Guthrie
- Department of Communication Sciences and Disorders, Northern Arizona University, 208 E. Pine Knoll Drive, Flagstaff, Arizona 86011, USA
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Herr DW. The Future of Neurotoxicology: A Neuroelectrophysiological Viewpoint. FRONTIERS IN TOXICOLOGY 2021; 3:1. [PMID: 34966904 PMCID: PMC8711081 DOI: 10.3389/ftox.2021.729788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Neuroelectrophysiology is an old science, dating to the 18th century when electrical activity in nerves was discovered. Such discoveries have led to a variety of neurophysiological techniques, ranging from basic neuroscience to clinical applications. These clinical applications allow assessment of complex neurological functions such as (but not limited to) sensory perception (vision, hearing, somatosensory function), and muscle function. The ability to use similar techniques in both humans and animal models increases the ability to perform mechanistic research to investigate neurological problems. Good animal to human homology of many neurophysiological systems facilitates interpretation of data to provide cause-effect linkages to epidemiological findings. Mechanistic cellular research to screen for toxicity often includes gaps between cellular and whole animal/person neurophysiological changes, preventing understanding of the complete function of the nervous system. Building Adverse Outcome Pathways (AOPs) will allow us to begin to identify brain regions, timelines, neurotransmitters, etc. that may be Key Events (KE) in the Adverse Outcomes (AO). This requires an integrated strategy, from in vitro to in vivo (and hypothesis generation, testing, revision). Scientists need to determine intermediate levels of nervous system organization that are related to an AO and work both upstream and downstream using mechanistic approaches. Possibly more than any other organ, the brain will require networks of pathways/AOPs to allow sufficient predictive accuracy. Advancements in neurobiological techniques should be incorporated into these AOP-base neurotoxicological assessments, including interactions between many regions of the brain simultaneously. Coupled with advancements in optogenetic manipulation, complex functions of the nervous system (such as acquisition, attention, sensory perception, etc.) can be examined in real time. The integration of neurophysiological changes with changes in gene/protein expression can begin to provide the mechanistic underpinnings for biological changes. Establishment of linkages between changes in cellular physiology and those at the level of the AO will allow construction of biological pathways (AOPs) and allow development of higher throughput assays to test for changes to critical physiological circuits. To allow mechanistic/predictive toxicology of the nervous system to be protective of human populations, neuroelectrophysiology has a critical role in our future.
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Affiliation(s)
- David W Herr
- Neurological and Endocrine Toxicology Branch, Public Health and Integrated Toxicology Division, CPHEA/ORD, U.S. Environmental Protection Agency, Washington, NC, United States
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Steyger PS. Mechanisms of Aminoglycoside- and Cisplatin-Induced Ototoxicity. Am J Audiol 2021; 30:887-900. [PMID: 34415784 PMCID: PMC9126111 DOI: 10.1044/2021_aja-21-00006] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 04/30/2021] [Accepted: 05/14/2021] [Indexed: 12/11/2022] Open
Abstract
Purpose This review article summarizes our current understanding of the mechanisms underlying acquired hearing loss from hospital-prescribed medications that affects as many as 1 million people each year in Western Europe and North America. Yet, there are currently no federally approved drugs to prevent or treat the debilitating and permanent hearing loss caused by the life-saving platinum-based anticancer drugs or the bactericidal aminoglycoside antibiotics. Hearing loss has long-term impacts on quality-of-life measures, especially in young children and older adults. This review article also highlights some of the current knowledge gaps regarding iatrogenic causes of hearing loss. Conclusion Further research is urgently needed to further refine clinical practice and better ameliorate iatrogenic drug-induced hearing loss.
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Affiliation(s)
- Peter S. Steyger
- Translational Hearing Center, Creighton University, Omaha, NE
- National Center for Rehabilitative Auditory Research, VA Portland Health Care System, OR
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Morata TC, Hungerford M, Konrad-Martin D. Potential Risks to Hearing Functions of Service Members From Exposure to Jet Fuels. Am J Audiol 2021; 30:922-927. [PMID: 34407375 DOI: 10.1044/2021_aja-20-00226] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Purpose Several military occupations, particularly those within the U.S. Air Force, require working with or around jet fuels. Jet fuels contain components that are known to affect central nervous function, yet effects of these fuels on auditory function, specifically auditory processing of sound, are not well understood at this time. Animal studies have demonstrated that exposure to jet fuels prior to noise exposure can exacerbate the noise exposure's effects, and service members exposed to jet fuels are at risk of noise exposure within their work environments. The purpose of this article was to give a brief synopsis of the evidence on the ototoxic effects due to jet fuel exposure to aid audiologists in their decision making when providing care for populations who are occupationally exposed to fuels or while during military service. Conclusions Exposure to jet fuels impacts central nervous function and, in combination with noise exposure, may have detrimental auditory effects that research has yet to fully explain. Additional longitudinal research is needed to explain the relationships, which have clinical implications for service members and others exposed to jet fuels. In the meantime, audiologists can gain useful information by screening for chemical exposures when obtaining patient case histories. If jet fuel exposure is suspected, the Lifetime Exposure to Noise and Solvents Questionnaire can be used to estimate a noise exposure ranking and identify other potentiating agents such as jet fuel and industrial chemicals. A history of jet fuel exposure should inform the selection of hearing tests in the audiometric evaluation and when devising the treatment plan.
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Affiliation(s)
- Thais C. Morata
- National Institute for Occupational Safety and Health, Cincinnati, OH
| | - Michelle Hungerford
- National Center for Rehabilitative Auditory Research, VA Portland Health Care System, OR
| | - Dawn Konrad-Martin
- National Center for Rehabilitative Auditory Research, VA Portland Health Care System, OR
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Sex differences in the auditory functions of rodents. Hear Res 2021; 419:108271. [PMID: 34074560 DOI: 10.1016/j.heares.2021.108271] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 04/07/2021] [Accepted: 04/28/2021] [Indexed: 12/30/2022]
Abstract
BACKGROUND In humans, it is well known that females have better hearing than males. The mechanism of this influence of sex on auditory function in humans is not well understood. Testing the hypothesis of underlying mechanisms often relies on preclinical research, a field in which sex bias still exists unconsciously. Rodents are popular research models in hearing, thus it is crucial to understand the sex differences in these rodent models when studying health and disease in humans. OBJECTIVES This review aims to summarize the existing sex differences in the auditory functions of rodent species including mouse, rat, Guinea pig, Mongolian gerbil, and chinchilla. In addition, a concise summary of the hearing characteristics and the advantages and the drawbacks of conducting auditory experiments in each rodent species is provided. DESIGNS Manuscripts were identified in PubMed and Ovid Medline for the queries "Rodent", "Sex Characteristics", and "Hearing or Auditory Function". Manuscripts were included if they were original research, written in English, and use rodents. The content of each manuscript was screened for the sex of the rodents and the discussion of sex-based results. CONCLUSIONS The sex differences in auditory function of rodents are prevalent and influenced by multiple factors including physiological mechanisms, sex-based anatomical variations, and stimuli from the external environment. Such differences may play a role in understanding and explaining sex differences in hearing of humans and need to be taken into consideration for developing clinical therapies aim to improve auditory performances.
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Bendtsen KM, Bengtsen E, Saber AT, Vogel U. A review of health effects associated with exposure to jet engine emissions in and around airports. Environ Health 2021; 20:10. [PMID: 33549096 PMCID: PMC7866671 DOI: 10.1186/s12940-020-00690-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 12/29/2020] [Indexed: 05/03/2023]
Abstract
BACKGROUND Airport personnel are at risk of occupational exposure to jet engine emissions, which similarly to diesel exhaust emissions include volatile organic compounds and particulate matter consisting of an inorganic carbon core with associated polycyclic aromatic hydrocarbons, and metals. Diesel exhaust is classified as carcinogenic and the particulate fraction has in itself been linked to several adverse health effects including cancer. METHOD In this review, we summarize the available scientific literature covering human health effects of exposure to airport emissions, both in occupational settings and for residents living close to airports. We also report the findings from the limited scientific mechanistic studies of jet engine emissions in animal and cell models. RESULTS Jet engine emissions contain large amounts of nano-sized particles, which are particularly prone to reach the lower airways upon inhalation. Size of particles and emission levels depend on type of aircraft, engine conditions, and fuel type, as well as on operation modes. Exposure to jet engine emissions is reported to be associated with biomarkers of exposure as well as biomarkers of effect among airport personnel, especially in ground-support functions. Proximity to running jet engines or to the airport as such for residential areas is associated with increased exposure and with increased risk of disease, increased hospital admissions and self-reported lung symptoms. CONCLUSION We conclude that though the literature is scarce and with low consistency in methods and measured biomarkers, there is evidence that jet engine emissions have physicochemical properties similar to diesel exhaust particles, and that exposure to jet engine emissions is associated with similar adverse health effects as exposure to diesel exhaust particles and other traffic emissions.
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Affiliation(s)
- Katja M. Bendtsen
- National Research Centre for the Working Environment, Lersø Parkallé 105, DK-2100 Copenhagen, Denmark
| | - Elizabeth Bengtsen
- National Research Centre for the Working Environment, Lersø Parkallé 105, DK-2100 Copenhagen, Denmark
| | - Anne T. Saber
- National Research Centre for the Working Environment, Lersø Parkallé 105, DK-2100 Copenhagen, Denmark
| | - Ulla Vogel
- National Research Centre for the Working Environment, Lersø Parkallé 105, DK-2100 Copenhagen, Denmark
- Department of Health Technology, Technical University of Denmark, DK-2800 Kgs Lyngby, Denmark
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Fuente A, Hickson L, Morata TC, Williams W, Khan A, Fuentes-Lopez E. Jet fuel exposure and auditory outcomes in Australian air force personnel. BMC Public Health 2019; 19:675. [PMID: 31151392 PMCID: PMC6544957 DOI: 10.1186/s12889-019-7038-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Accepted: 05/23/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Animal data suggest that jet fuels such as JP-8 are associated with hearing deficits when combined with noise and that the effect is more pronounced than with noise exposure alone. Some studies suggest peripheral dysfunction while others suggest central auditory dysfunction. Human data are limited in this regard. The aim of this study was to investigate the possible chronic adverse effects of JP-8 combined with noise exposure on the peripheral and central auditory systems in humans. METHODS Fifty-seven participants who were current personnel from the Royal Australian Air Force were selected. Based on their levels of exposure to jet fuels, participants were divided into three exposure groups (low, moderate, high). Groups were also categorised based on their noise exposure levels (low, moderate, high). All participants were evaluated by tympanometry, pure-tone audiometry (1-12 kHz), distortion product otoacoustic emissions (DPOAEs), auditory brainstem response (ABR), words-in-noise, compressed speech, dichotic digit test, pitch pattern sequence test, duration pattern sequence test and adaptive test of temporal resolution. All auditory tests were carried out after the participants were away from the Air Force base for a minimum of two weeks, thus two weeks without jet fuel and noise exposure. RESULTS Jet fuel exposure was significantly associated with hearing thresholds at 4 and 8 kHz; average hearing thresholds across frequencies in the better ear; DPOAEs at 2.8, 4 and 6 kHz; ABR wave V latency in the right ear; compressed speech and words-in-noise. Further analyses revealed that participants with low exposure level to jet fuels showed significantly better results for the aforementioned procedures than participants with moderate and high exposure levels. All results were controlled for the covariates of age and noise exposure levels. CONCLUSIONS The results suggest that jet fuel exposure, when combined with noise exposure, has an adverse effect on audibility in humans. Taking all the test results into consideration, jet fuel exposure combined with noise exposure specifically seems to affect the peripheral hearing system in humans.
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Affiliation(s)
- Adrian Fuente
- School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Australia. .,Centre de recherche de l'Institut universitaire de gériatrie de Montréal, Montreal, Quebec, Canada.
| | - Louise Hickson
- School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Australia
| | - Thais C Morata
- National Institute for Occupational Safety and Health, Cincinnati, OH, USA
| | | | - Asaduzzaman Khan
- School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Australia
| | - Eduardo Fuentes-Lopez
- Carrera de Fonoaudiología, Departamento de Ciencias de la Salud, Pontificia Universidad Católica de Chile, Santiago, Chile
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Grobe N, Narayanan L, Brown DN, Law ST, Sibomana I, Shiyanov P, Reo NV, Hack CE, Sterner TR, Mattie DR. Lipid, water, and protein composition to facilitate kinetic modeling of the auditory pathway. Toxicol Mech Methods 2018; 29:53-59. [PMID: 30084267 DOI: 10.1080/15376516.2018.1508263] [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: 10/28/2022]
Abstract
Environments combining JP-8 jet fuel exposure with heightened ambient noise may accelerate hearing loss induced by noise. To reduce animal use and facilitate kinetic modeling of this military aviation fuel, tissue-specific parameters are required, including water, protein, and lipid content. However, tissues involved in hearing, including cochlea, brainstem, frontal, and temporal lobe, have not been characterized before. Therefore, water content was determined by lyophilization of rat auditory tissues and the protein of the freeze dried remainder was quantified using a bicinchoninic acid assay. Lipids were extracted from fresh-frozen rat auditory tissues and separated into neutral lipids, free fatty acids, neutral phospholipids, and acidic phospholipids using solid phase extraction. Phospholipid fractions were confirmed by 31 P nuclear magnetic resonance analysis showing distinct phospholipid profiles. Lipid content in reference tissues, such as kidney and adipose, confirmed literature values. For the first time, lipid content in the rat auditory pathway was determined showing that total lipid content was lowest in cochlea and highest in brainstem compared with frontal and temporal lobes. Auditory tissues displayed distinct lipid fraction profiles. The information on water, protein, and lipid composition is necessary to validate algorithms used in mathematical models and predict partitioning of chemicals of future interest into these tissues. This research may reduce the use of animals to measure partition coefficients for prospective physiological models.
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Affiliation(s)
- Nadja Grobe
- a Molecular Mechanisms Branch, Human Centered ISR Division , Airman Systems Directorate, 711th Human Performance Wing (711HPW/RHXJ), Air Force Research Laboratory , Wright-Patterson Air Force Base , OH , USA
| | - Latha Narayanan
- a Molecular Mechanisms Branch, Human Centered ISR Division , Airman Systems Directorate, 711th Human Performance Wing (711HPW/RHXJ), Air Force Research Laboratory , Wright-Patterson Air Force Base , OH , USA.,b Henry M. Jackson Foundation for the Advancement of Military Medicine (HJF) , Wright-Patterson Air Force Base , OH , USA
| | - Dominique N Brown
- a Molecular Mechanisms Branch, Human Centered ISR Division , Airman Systems Directorate, 711th Human Performance Wing (711HPW/RHXJ), Air Force Research Laboratory , Wright-Patterson Air Force Base , OH , USA
| | - Sarah T Law
- a Molecular Mechanisms Branch, Human Centered ISR Division , Airman Systems Directorate, 711th Human Performance Wing (711HPW/RHXJ), Air Force Research Laboratory , Wright-Patterson Air Force Base , OH , USA.,b Henry M. Jackson Foundation for the Advancement of Military Medicine (HJF) , Wright-Patterson Air Force Base , OH , USA
| | - Isaie Sibomana
- a Molecular Mechanisms Branch, Human Centered ISR Division , Airman Systems Directorate, 711th Human Performance Wing (711HPW/RHXJ), Air Force Research Laboratory , Wright-Patterson Air Force Base , OH , USA.,c Department of Biochemistry and Molecular Biology Magnetic Resonance Laboratory, Boonshoft School of Medicine , Wright State University , Dayton , OH , USA
| | - Pavel Shiyanov
- a Molecular Mechanisms Branch, Human Centered ISR Division , Airman Systems Directorate, 711th Human Performance Wing (711HPW/RHXJ), Air Force Research Laboratory , Wright-Patterson Air Force Base , OH , USA.,b Henry M. Jackson Foundation for the Advancement of Military Medicine (HJF) , Wright-Patterson Air Force Base , OH , USA
| | - Nicholas V Reo
- c Department of Biochemistry and Molecular Biology Magnetic Resonance Laboratory, Boonshoft School of Medicine , Wright State University , Dayton , OH , USA
| | - C Eric Hack
- a Molecular Mechanisms Branch, Human Centered ISR Division , Airman Systems Directorate, 711th Human Performance Wing (711HPW/RHXJ), Air Force Research Laboratory , Wright-Patterson Air Force Base , OH , USA.,b Henry M. Jackson Foundation for the Advancement of Military Medicine (HJF) , Wright-Patterson Air Force Base , OH , USA
| | - Teresa R Sterner
- a Molecular Mechanisms Branch, Human Centered ISR Division , Airman Systems Directorate, 711th Human Performance Wing (711HPW/RHXJ), Air Force Research Laboratory , Wright-Patterson Air Force Base , OH , USA.,b Henry M. Jackson Foundation for the Advancement of Military Medicine (HJF) , Wright-Patterson Air Force Base , OH , USA
| | - David R Mattie
- a Molecular Mechanisms Branch, Human Centered ISR Division , Airman Systems Directorate, 711th Human Performance Wing (711HPW/RHXJ), Air Force Research Laboratory , Wright-Patterson Air Force Base , OH , USA
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Fife TD, Robb MJA, Steenerson KK, Saha KC. Bilateral Vestibular Dysfunction Associated With Chronic Exposure to Military Jet Propellant Type-Eight Jet Fuel. Front Neurol 2018; 9:351. [PMID: 29867750 PMCID: PMC5964212 DOI: 10.3389/fneur.2018.00351] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 05/01/2018] [Indexed: 12/19/2022] Open
Abstract
We describe three patients diagnosed with bilateral vestibular dysfunction associated with the jet propellant type-eight (JP-8) fuel exposure. Chronic exposure to aromatic and aliphatic hydrocarbons, which are the main constituents of JP-8 military aircraft jet fuel, occurred over 3–5 years’ duration while working on or near the flight line. Exposure to toxic hydrocarbons was substantiated by the presence of JP-8 metabolite n-hexane in the blood of one of the cases. The presenting symptoms were dizziness, headache, fatigue, and imbalance. Rotational chair testing confirmed bilateral vestibular dysfunction in all the three patients. Vestibular function improved over time once the exposure was removed. Bilateral vestibular dysfunction has been associated with hydrocarbon exposure in humans, but only recently has emphasis been placed specifically on the detrimental effects of JP-8 jet fuel and its numerous hydrocarbon constituents. Data are limited on the mechanism of JP-8-induced vestibular dysfunction or ototoxicity. Early recognition of JP-8 toxicity risk, cessation of exposure, and customized vestibular therapy offer the best chance for improved balance. Bilateral vestibular impairment is under-recognized in those chronically exposed to all forms of jet fuel.
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Affiliation(s)
- Terry D Fife
- Barrow Neurological Institute, Phoenix, AZ, United States
| | | | | | - Kamala C Saha
- Barrow Neurological Institute, Phoenix, AZ, United States
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Background Noise Contributes to Organic Solvent Induced Brain Dysfunction. Neural Plast 2016; 2016:8742725. [PMID: 26885406 PMCID: PMC4739468 DOI: 10.1155/2016/8742725] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 12/22/2015] [Indexed: 12/13/2022] Open
Abstract
Occupational exposure to complex blends of organic solvents is believed to alter brain functions among workers. However, work environments that contain organic solvents are also polluted with background noise which raises the issue of whether or not the noise contributed to brain alterations. The purpose of the current study was to determine whether or not repeated exposure to low intensity noise with and without exposure to a complex blend of organic solvents would alter brain activity. Female Fischer344 rats served as subjects in these experiments. Asynchronous volume conductance between the midbrain and cortex was evaluated with a slow vertex recording technique. Subtoxic solvent exposure, by itself, had no statistically significant effects. However, background noise significantly suppressed brain activity and this suppression was exacerbated with solvent exposure. Furthermore, combined exposure produced significantly slow neurotransmission. These abnormal neurophysiologic findings occurred in the absence of hearing loss and detectable damage to sensory cells. The observations from the current experiment raise concern for all occupations where workers are repeatedly exposed to background noise or noise combined with organic solvents. Noise levels and solvent concentrations that are currently considered safe may not actually be safe and existing safety regulations have failed to recognize the neurotoxic potential of combined exposures.
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Stubbs JE, Slagley JM, Reboulet JE. A noise delivery system for multi-animal multi-level whole body ototoxicity studies. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2015; 138:3181-3187. [PMID: 26627791 DOI: 10.1121/1.4935392] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The Naval Medical Research Unit Dayton (NAMRU-D) at Wright-Patterson Air Force Base, Ohio, in conjunction with the U.S. Air Force, studied ototoxic effects of JP-8 in rats. NAMRU-D used a multi-chamber whole body exposure facility for up to 96 test animals and 32 control animals at different exposure levels. The objective was to design a noise delivery system that could provide a white noise source one octave band wide, centered at 8 kHz frequency, delivered from outside the exposure chambers. Sound pressure levels were required to be within ±2 dB at all exposure points within each chamber and within ±2 dB over a 6-h run. Electrodynamic shakers were used to produce input noise in exposure chambers by inducing vibration in chamber plenums. Distribution of sound pressure levels across exposure points was controlled within a ±1.5dB prediction interval (α = 0.05) or better. Stability at a central reference point was controlled over 6-h runs within a ±1 dB prediction interval (α = 0.05) or better. The final system allowed NAMRU-D to deliver noise and whole-body aerosol exposures to multiple animals at different levels simultaneously and study the effects that ototoxins may have on hearing loss.
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Affiliation(s)
- John E Stubbs
- Air Force Institute of Technology, Department of Systems Engineering and Management, Wright-Patterson Air Force Base, Ohio 45433, USA
| | - Jeremy M Slagley
- Air Force Institute of Technology, Department of Systems Engineering and Management, Wright-Patterson Air Force Base, Ohio 45433, USA
| | - James E Reboulet
- Naval Medical Research Unit Dayton, Wright-Patterson Air Force Base, Ohio 45433, USA
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Guthrie OW, Wong BA, McInturf SM, Reboulet JE, Ortiz PA, Mattie DR. Inhalation of Hydrocarbon Jet Fuel Suppress Central Auditory Nervous System Function. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2015; 78:1154-1169. [PMID: 26408153 DOI: 10.1080/15287394.2015.1070389] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
More than 800 million L/d of hydrocarbon fuels is used to power cars, boats, and jet airplanes. The weekly consumption of these fuels necessarily puts the public at risk for repeated inhalation exposure. Recent studies showed that exposure to hydrocarbon jet fuel produces lethality in presynaptic sensory cells, leading to hearing loss, especially in the presence of noise. However, the effects of hydrocarbon jet fuel on the central auditory nervous system (CANS) have not received much attention. It is important to investigate the effects of hydrocarbons on the CANS in order to complete current knowledge regarding the ototoxic profile of such exposures. The objective of the current study was to determine whether inhalation exposure to hydrocarbon jet fuel might affect the functions of the CANS. Male Fischer 344 rats were randomly divided into four groups (control, noise, fuel, and fuel + noise). The structural and functional integrity of presynaptic sensory cells was determined in each group. Neurotransmission in both peripheral and central auditory pathways was simultaneously evaluated in order to identify and differentiate between peripheral and central dysfunctions. There were no detectable effects on pre- and postsynaptic peripheral functions. However, the responsiveness of the brain was significantly depressed and neural transmission time was markedly delayed. The development of CANS dysfunctions in the general public and the military due to cumulative exposure to hydrocarbon fuels may represent a significant but currently unrecognized public health issue.
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Affiliation(s)
- O'neil W Guthrie
- a Cell & Molecular Pathology Laboratory, Department of Communication Sciences and Disorders , Northern Arizona University , Flagstaff , Arizona , USA
- b Research Service, Loma Linda Veterans Affairs Medical Center , Loma Linda , California , USA
- c Department of Otolaryngology and Head & Neck Surgery , School of Medicine, Loma Linda University Medical Center , Loma Linda , California , USA
| | - Brian A Wong
- d Naval Medical Research Unit-Dayton , Wright-Patterson Air Force Base , Ohio , USA
| | - Shawn M McInturf
- d Naval Medical Research Unit-Dayton , Wright-Patterson Air Force Base , Ohio , USA
| | - James E Reboulet
- d Naval Medical Research Unit-Dayton , Wright-Patterson Air Force Base , Ohio , USA
| | - Pedro A Ortiz
- d Naval Medical Research Unit-Dayton , Wright-Patterson Air Force Base , Ohio , USA
| | - David R Mattie
- e Molecular Bioeffects Branch, Bioeffects Division, Human Effectiveness Directorate , Air Force Research Laboratory, Wright Patterson Air Force Base , Ohio , USA
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Cannizzaro E, Cannizzaro C, Plescia F, Martines F, Soleo L, Pira E, Lo Coco D. Exposure to ototoxic agents and hearing loss: A review of current knowledge. HEARING BALANCE AND COMMUNICATION 2014. [DOI: 10.3109/21695717.2014.964939] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Guthrie OW, Xu H, Wong BA, McInturf SM, Reboulet JE, Ortiz PA, Mattie DR. Exposure to low levels of jet-propulsion fuel impairs brainstem encoding of stimulus intensity. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2014; 77:261-280. [PMID: 24588226 DOI: 10.1080/15287394.2013.862892] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Jet propulsion fuel-8 (JP-8) is a kerosene-based fuel that is used in military jets. The U.S. Armed Services and North Atlantic Treaty Organization countries adopted JP-8 as a standard fuel source and the U.S. military alone consumes more than 2.5 billion gallons annually. Preliminary epidemiologic data suggested that JP-8 may interact with noise to induce hearing loss, and animal studies revealed damage to presynaptic sensory cells in the cochlea. In the current study, Long-Evans rats were divided into four experimental groups: control, noise only, JP-8 only, and JP-8 + noise. A subototoxic level of JP-8 was used alone or in combination with a nondamaging level of noise. Functional and structural assays of the presynaptic sensory cells combined with neurophysiologic studies of the cochlear nerve revealed that peripheral auditory function was not affected by individual exposures and there was no effect when the exposures were combined. However, the central auditory nervous system exhibited impaired brainstem encoding of stimulus intensity. These findings may represent important and major shifts in the theoretical framework that governs current understanding of jet fuel and/or jet fuel + noise-induced ototoxicity. From an epidemiologic perspective, results indicate that jet fuel exposure may exert consequences on auditory function that may be more widespread and insidious than what was previously shown. It is possible that a large population of military personnel who are suffering from the effects of jet fuel exposure may be misidentified because they would exhibit normal hearing thresholds but harbor a "hidden" brainstem dysfunction.
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Affiliation(s)
- O'neil W Guthrie
- a Research Service-151, Loma Linda Veterans Affairs Medical Center , Loma Linda , California , USA
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Baiduc RR, Poling GL, Hong O, Dhar S. Clinical measures of auditory function: the cochlea and beyond. Dis Mon 2013; 59:147-56. [PMID: 23507354 DOI: 10.1016/j.disamonth.2013.01.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Martin SA, Campbell JL, Tremblay RT, Fisher JW. Development of a physiologically based pharmacokinetic model for inhalation of jet fuels in the rat. Inhal Toxicol 2011; 24:1-26. [DOI: 10.3109/08958378.2011.631297] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Abstract
The modern era of evidence-based ototoxicity emerged in the 1940s following the discovery of aminoglycosides and their ototoxic side effects. New classes of ototoxins have been identified in subsequent decades, notably loop diuretics, antineoplastic drugs, and metal chelators. Ototoxic drugs are frequently nephrotoxic, as both organs regulate fluid and ion composition. The mechanisms of ototoxicity are as diverse as the pharmacological properties of each ototoxin, though the generation of toxic levels of reactive oxygen species appears to be a common denominator. As mechanisms of cytotoxicity for each ototoxin continue to be elucidated, a new frontier in ototoxicity is emerging: How do ototoxins cross the blood-labyrinth barrier that tightly regulates the composition of the inner ear fluids? Increased knowledge of the mechanisms by which systemic ototoxins are trafficked across the blood-labyrinth barrier into the inner ear is critical to developing new pharmacotherapeutic agents that target the blood-labyrinth barrier to prevent trafficking of ototoxic drugs and their cytotoxic sequelae.
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Affiliation(s)
- Peter S Steyger
- Oregon Hearing Research Center, Oregon Health and Science University, Portland, Oregon
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24
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Mattie DR, Sterner TR. Past, present and emerging toxicity issues for jet fuel. Toxicol Appl Pharmacol 2011; 254:127-32. [DOI: 10.1016/j.taap.2010.04.022] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Revised: 04/09/2010] [Accepted: 04/09/2010] [Indexed: 10/18/2022]
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Yang Y, Dai M, Wilson TM, Omelchenko I, Klimek JE, Wilmarth PA, David LL, Nuttall AL, Gillespie PG, Shi X. Na+/K+-ATPase α1 identified as an abundant protein in the blood-labyrinth barrier that plays an essential role in the barrier integrity. PLoS One 2011; 6:e16547. [PMID: 21304972 PMCID: PMC3031570 DOI: 10.1371/journal.pone.0016547] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 12/21/2010] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND The endothelial-blood/tissue barrier is critical for maintaining tissue homeostasis. The ear harbors a unique endothelial-blood/tissue barrier which we term "blood-labyrinth-barrier". This barrier is critical for maintaining inner ear homeostasis. Disruption of the blood-labyrinth-barrier is closely associated with a number of hearing disorders. Many proteins of the blood-brain-barrier and blood-retinal-barrier have been identified, leading to significant advances in understanding their tissue specific functions. In contrast, capillaries in the ear are small in volume and anatomically complex. This presents a challenge for protein analysis studies, which has resulted in limited knowledge of the molecular and functional components of the blood-labyrinth-barrier. In this study, we developed a novel method for isolation of the stria vascularis capillary from CBA/CaJ mouse cochlea and provided the first database of protein components in the blood-labyrinth barrier as well as evidence that the interaction of Na(+)/K(+)-ATPase α1 (ATP1A1) with protein kinase C eta (PKCη) and occludin is one of the mechanisms of loud sound-induced vascular permeability increase. METHODOLOGY/PRINCIPAL FINDINGS Using a mass-spectrometry, shotgun-proteomics approach combined with a novel "sandwich-dissociation" method, more than 600 proteins from isolated stria vascularis capillaries were identified from adult CBA/CaJ mouse cochlea. The ion transporter ATP1A1 was the most abundant protein in the blood-labyrinth barrier. Pharmacological inhibition of ATP1A1 activity resulted in hyperphosphorylation of tight junction proteins such as occludin which increased the blood-labyrinth-barrier permeability. PKCη directly interacted with ATP1A1 and was an essential mediator of ATP1A1-initiated occludin phosphorylation. Moreover, this identified signaling pathway was involved in the breakdown of the blood-labyrinth-barrier resulting from loud sound trauma. CONCLUSIONS/SIGNIFICANCE The results presented here provide a novel method for capillary isolation from the inner ear and the first database on protein components in the blood-labyrinth-barrier. Additionally, we found that ATP1A1 interaction with PKCη and occludin was involved in the integrity of the blood-labyrinth-barrier.
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Affiliation(s)
- Yue Yang
- Department of Otolaryngology/Head and Neck Surgery, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Min Dai
- Department of Otolaryngology/Head and Neck Surgery, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Teresa M. Wilson
- Department of Otolaryngology/Head and Neck Surgery, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Irina Omelchenko
- Department of Otolaryngology/Head and Neck Surgery, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
| | - John E. Klimek
- Proteomic Shared Resources, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Phillip A. Wilmarth
- Proteomic Shared Resources, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Larry L. David
- Proteomic Shared Resources, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Alfred L. Nuttall
- Department of Otolaryngology/Head and Neck Surgery, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
- Kresge Hearing Research Institute, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Otolaryngology, Renji Hospital, Shanghai Jiao Tong University, Shanghai, China
| | - Peter G. Gillespie
- Department of Otolaryngology/Head and Neck Surgery, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
- Vollum Institute, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Xiaorui Shi
- Department of Otolaryngology/Head and Neck Surgery, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
- Department of Otolaryngology, Renji Hospital, Shanghai Jiao Tong University, Shanghai, China
- The Institute of Microcirculation, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
- * E-mail:
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Tremblay RT, Martin SA, Fisher JW. Metabolites from inhalation of aerosolized S-8 synthetic jet fuel in rats. Inhal Toxicol 2011; 23:11-6. [PMID: 21222558 DOI: 10.3109/08958378.2010.535573] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Alternative fuels are being considered for civilian and military uses. One of these is S-8, a replacement jet fuel synthesized using the Fischer-Tropsch process, which contains no aromatic compounds and is mainly composed of straight and branched alkanes. Metabolites of S-8 fuel in laboratory animals have not been identified. The goal of this study was to identify metabolic products from exposure to aerosolized S-8 and a designed straight-chain alkane/polyaromatic mixture (decane, undecane, dodecane, tridecane, tetradecane, pentadecane, naphthalene, and 2-methylnaphthalene) in male Fischer 344 rats. Collected blood and tissue samples were analyzed for 70 straight and branched alcohols and ketones ranging from 7 to 15 carbons. No fuel metabolites were observed in the blood, lungs, brain, and fat following S-8 exposure. Metabolites were detected in the liver, urine, and feces. Most of the metabolites were 2- and 3-position alcohols and ketones of prominent hydrocarbons with very few 1- or 4-position metabolites. Following exposure to the alkane mixture, metabolites were observed in the blood, liver, and lungs. Interestingly, heavy metabolites (3-tridecanone, 2-tridecanol, and 2-tetradecanol) were observed only in the lung tissues possibly indicating that metabolism occurred in the lungs. With the exception of these heavy metabolites, the metabolic profiles observed in this study are consistent with previous studies reporting on the metabolism of individual alkanes. Further work is needed to determine the potential metabolic interactions of parent, primary, and secondary metabolites and identify more polar metabolites. Some metabolites may have potential use as biomarkers of exposure to fuels.
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Affiliation(s)
- Raphael T Tremblay
- Interdisciplinary Toxicology Program, University of Georgia, Athens, GA, USA.
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Guest M, Boggess M, Attia J, D'Este C, Brown A, Gibson R, Tavener M, Gardner I, Harrex W, Horsley K, Ross J. Hearing impairment in F-111 maintenance workers: the study of health outcomes in aircraft maintenance personnel (SHOAMP) general health and medical study. Am J Ind Med 2010; 53:1159-69. [PMID: 20593381 DOI: 10.1002/ajim.20867] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND We sought to examine hearing loss in a group from the Royal Australian Air Force who undertook fuel tank maintenance on F-111 aircraft, with exposure to formulations containing ototoxins, relative to two different comparison groups. METHODS Using pure-tone audiometry, hearing thresholds were assessed in 614 exposed personnel, 513 technical-trade comparisons (different base, same job), and 403 non-technical comparisons (same base, different job). We calculated percentage loss of hearing (PLH) and used regression models to examine whether there was an association between PLH and F-111 fuel tank maintenance, adjusting for possible confounders. In addition, the difference between the observed hearing thresholds and the expected thresholds based on an otologically normal population (ISO-7029-2003) was determined. RESULTS The PLH ranged from nil to 96 (median 1.5, quartiles 0.3, 5.5). A logistic regression model showed no statistically significant difference in PLH among the three exposure groups (exposed vs. non-technical controls 1.1: 95% CI 0.7, 2.0 and exposed vs. technical OR 0.9: 95% CI 0.6, 1.3). The model also highlighted a number of other risk factors for PLH including age, tinnitus, smoking, depression, and use of depression medications. However, at all eight frequencies measured, all populations had lower than expected hearing thresholds based on published ISO-7029 medians. CONCLUSIONS Although there was no difference in PLH between the three exposure groups, the study did reveal a high degree of hearing loss between the 3 groups and a normal population.
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Affiliation(s)
- Maya Guest
- University of Newcastle, NSW, Australia.
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Martin SA, Tremblay RT, Brunson KF, Kendrick C, Fisher JW. Characterization of a nose-only inhalation exposure system for hydrocarbon mixtures and jet fuels. Inhal Toxicol 2010; 22:382-93. [PMID: 20109056 DOI: 10.3109/08958370903456645] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
A directed-flow nose-only inhalation exposure system was constructed to support development of physiologically based pharmacokinetic (PBPK) models for complex hydrocarbon mixtures, such as jet fuels. Due to the complex nature of the aerosol and vapor-phase hydrocarbon exposures, care was taken to investigate the chamber hydrocarbon stability, vapor and aerosol droplet compositions, and droplet size distribution. Two-generation systems for aerosolizing fuel and hydrocarbons were compared and characterized for use with either jet fuels or a simple mixture of eight hydrocarbons. Total hydrocarbon concentration was monitored via online gas chromatography (GC). Aerosol/vapor (A/V) ratios, and total and individual hydrocarbon concentrations, were determined using adsorbent tubes analyzed by thermal desorption-gas chromatography-mass spectrometry (TDS-GC-MS). Droplet size distribution was assessed via seven-stage cascade impactor. Droplet mass median aerodynamic diameter (MMAD) was between 1 and 3 mum, depending on the generator and mixture utilized. A/V hydrocarbon concentrations ranged from approximately 200 to 1300 mg/m(3), with between 20% and 80% aerosol content, depending on the mixture. The aerosolized hydrocarbon mixtures remained stable during the 4-h exposure periods, with coefficients of variation (CV) of less than 10% for the total hydrocarbon concentrations. There was greater variability in the measurement of individual hydrocarbons in the A-V phase. In conclusion, modern analytical chemistry instruments allow for improved descriptions of inhalation exposures of rodents to aerosolized fuel.
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Affiliation(s)
- Sheppard A Martin
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, Georgia 30602, USA.
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Tremblay RT, Martin SA, Fisher JW. Novel characterization of the aerosol and gas-phase composition of aerosolized jet fuel. Inhal Toxicol 2010; 22:394-401. [DOI: 10.3109/08958370903456637] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Wright AJ, Deak T, Parsons ECM. Size matters: management of stress responses and chronic stress in beaked whales and other marine mammals may require larger exclusion zones. MARINE POLLUTION BULLETIN 2010; 63:5-9. [PMID: 20045527 DOI: 10.1016/j.marpolbul.2009.11.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Revised: 11/26/2009] [Accepted: 11/29/2009] [Indexed: 05/28/2023]
Abstract
Marine mammal management traditionally focuses on lethal takes, but non-lethal (or not immediately lethal) impacts of human disturbance, such as prolonged or repeated activation of the stress response, can also have serious conservation implications. The physiological stress response is a life-saving combination of systems and events that maximises the ability of an animal to kill or avoid being killed. However, "chronic stress" is linked to numerous conditions in humans, including coronary disease and infertility. Through examples, including beaked whales and sonar exposure, we discuss increasing human disturbance, mal-adaptive stress responses and chronic stress. Deep-diving and coastal species, and those targeted by whalewatching, may be particularly vulnerable. The various conditions linked with chronic stress in humans would have troubling implications for conservation efforts in endangered species, demands management attention, and may partly explain why some species have not recovered after protective measures (e.g., smaller protected areas) have been put into place.
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Affiliation(s)
- Andrew J Wright
- National Environmental Research Institute, Department for Arctic Environment, Aarhus University, Frederiksborgvej, Postboks, Roskilde, Denmark.
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Abstract
High-intensity and/or prolonged exposure to noise causes temporary or permanent threshold shifts in auditory perception. Occupational exposure to solvents or administration of clinically important drugs, such as aminoglycoside antibiotics and cisplatin, also can induce permanent hearing loss. The mechanisms by which these ototoxic insults cause auditory dysfunction are still being unraveled, yet they share common sequelae, particularly generation of reactive oxygen species, that ultimately lead to hearing loss and deafness. Individuals are frequently exposed to ototoxic chemical contaminants (e.g., fuel) and noise simultaneously in a variety of work and recreational environments. Does simultaneous exposure to chemical ototoxins and noise potentiate auditory dysfunction? Exposure to solvent vapor in noisy environments potentiates the permanent threshold shifts induced by noise alone. Moderate noise levels potentiate both aminoglycoside- and cisplatin-induced ototoxicity in both rate of onset and in severity of auditory dysfunction. Thus, simultaneous exposure to chemical ototoxins and moderate levels of noise can potentiate auditory dysfunction. Preventing the ototoxic synergy of noise and chemical ototoxins requires removing exposure to ototoxins and/or attenuating noise exposure levels when chemical ototoxins are present.
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Affiliation(s)
- Peter S Steyger
- Oregon Hearing Research Center, Oregon Health, Sciences University, Portland, Oregon
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Fechter LD, Nelson-Miller A, Gearhart C. Depletion of liver glutathione levels in rats: a potential confound of nose-only inhalation. Inhal Toxicol 2008; 20:885-90. [PMID: 18645729 DOI: 10.1080/08958370801975329] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Nose-only inhalation exposure chambers offer key advantages to whole-body systems, particularly when aerosol or mixed aerosol-vapor exposures are used. Specifically, nose-only chambers provide enhanced control over the route of exposure and dose by minimizing the deposition of particles either on the subjects skin/fur or on surfaces of a whole-body exposure system. In the current series of experiments, liver, brain, and lung total glutathione (GSH) levels were assessed following either nose-only or whole-body exposures to either jet fuel or to clean, filtered air. The data were compared to untreated control subjects. Acute nose-only inhalation exposures of rats resulted in a significant depletion of liver GSH levels both in subjects that were exposed to clean, filtered air as well as those exposed to JP-8 jet fuel and to a synthetic jet fuel. Glutathione levels were not altered in lung or brain tissue. Whole-body inhalation exposure had no effect on GSH levels in any tissue for any of the treatment groups. A second experiment demonstrated that the loss of GSH did not occur if rats were anaesthetized prior to and during nose-only exposure to clean, filtered air or to mixed hydrocarbons. These data appear to be consistent with studies demonstrating depletion in liver GSH levels among rats subjected to restraint stress. Finally, the depletion of GSH that was observed in liver following a single acute exposure was reduced following five daily exposures to clean, filtered air, suggesting the possibility of habituation to restraint in the nose-only exposure chamber. The finding that placement in a nose-only exposure chamber per se yields liver GSH depletion raises the possibility of an interaction between this mode of toxicant exposure and the toxicological effects of certain inhaled test substances.
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Kanno S, Furuyama A, Hirano S. Effects of eicosane, a component of nanoparticles in diesel exhaust, on surface activity of pulmonary surfactant monolayers. Arch Toxicol 2008; 82:841-50. [PMID: 18488198 DOI: 10.1007/s00204-008-0306-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Accepted: 04/21/2008] [Indexed: 10/22/2022]
Abstract
Recently, it has been reported that n-alkanes are principal components of diesel exhaust nanoparticles. We investigated the effects of n-alkanes on the surface activity of a pulmonary surfactant monolayer using both fresh surfactant isolated from mouse lungs, and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), a major component of lung surfactant. To examine the effect of n-alkanes on the surfactant, we compared surface pressure/trough area isotherm features and topographic images of DPPC in the presence and absence of a specific n-alkane (eicosane, C(20)H(42)) by Langmuir-Wilhelmy methods. The pure DPPC isotherm shows a typical plateau feature at a monolayer collapse pressure of 70 mN/m. The collapse pressure diminishes with increasing concentration of eicosane in DPPC. DPPC monolayers containing eicosane exhibit isotherms with one phase transition, but not the coexistence plateau of a liquid-expanded (LE) and liquid-condensed (LC) phase observed with a pure DPPC monolayer. Atomic force microscopy studies suggest that a DPPC monolayer containing eicosane has the phase transition from LE phase to LC phase and the protrusions are squeezed out from the monolayer, below the phase transition. On the other hand, eicosane changes the isotherm from mouse lung surfactant less dramatically than that of DPPC. The addition of increasing amounts of eicosane to mouse surfactant increases surface compressibility at 30 mN/m during the second compression, suggesting that the deposition of alkane-rich nanoparticles onto pulmonary surfactants may be related to dysfunction of surfactant activity during breathing.
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Affiliation(s)
- Sanae Kanno
- Environmental Nanotoxicology Section, Research Center for Environmental Risk, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
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