The Application of GEE and GEE/R-PIA Prior to Noise Exposure
CDR Nancy Hight, MSC, USN
The possibility that reactive oxygen species (ROS) may play a role in noise induced hearing loss has been explored recently. If ROS do contribute to cochlear pathology following noise exposure, than providing increased antioxidant availability before noise exposure should diminish the damage. Glutathione (GSH) is one of the most prevalent antioxidants in human tissue, and it has been found to be present in increased amounts in cochlear fluids following noise exposure. This study looks at providing the ear with glutathione monoethyl ester (GEE), a glutathione analogue, and R-phenylisopropyladenosine (R-PIA) an adenosine analogue shown to upregulate antioxidants, before either a continuous or an impulse noise exposure. The amount of hearing loss and hair cell loss will be compared between the control ear and the ear where the GEE or the GEE/R-PIA have been placed on the round window prior to noise exposure.
Supported by the Office of Naval Research.
Occupational Hearing Loss in A US Navy Active Duty Enlisted Population
Jan, MH. Department of Preventive Medicine and Biometrics,
Uniformed Services University of the Health Sciences, Bethesda, MD.
Background: Many Navy personnel are exposed to significant levels of noise in the course of their jobs. This study examines hearing loss in specific occupational groups using Hearing Conservation Program audiograms from a Navy active duty enlisted population.
Methods: Annual and termination audiograms with accompanying demographic information were analyzed in a database of Navy Hearing Conservation Program (HCP) audiograms. The definition of positive significant threshold shift (STS) followed current Navy policy using the 15 and 10 dB rules. The proportion of positive STS was determined overall and by occupation as represented by general rating (the 2 or 3 letter designator). Unconditional logistic regression of positive STS on age, sex, race, rating group, length of service, time interval between the current and reference audiogram, and the year the current audiogram was performed. The ratings group classification is used by the Navy Personnel Command (NPC) to organize related general ratings into manageable groups. Relative odds ratios for positive STS were calculated by year and ratings group.
Results: 3,387 annual or termination HCP audiograms from 1992-1998 were analyzed. The overall proportion of positive STS was 35.6% (95% CI 34.0-37.4). 16 general ratings demonstrated a lower 95% confidence limit for proportion of positive STS ( 25% and included Opticalman, Aviation Electrician’s Mate, Machinery Repairman, Builder, Torpedoman’s Mate, among others. The Medical/Dental ratings group demonstrated the lowest proportion of positive STS. Using this group as reference, significantly ((=0.05) elevated RORs for positive STS were obtained for Seabees (ROR 2.3, 95% CI 1.1-4.8) and the Technical group (ROR 2.1, 95% CI 1.1-3.8). RORs for positive STS by year of audiogram were not significantly different ((=0.05) with respect to the reference year of 1992.
Discussion: This study suggests that many Navy enlisted personnel continue to be exposed to high levels of noise in the occupational setting. Specific occupational groups that may be at highest risk include Seabees and the Technical ratings. In addition, the results suggest that the risk of positive STS did not significantly change from 1992-1998.
The 270 dB Program: Fitness for Continuing to Work in a Hazardous Noise Environment
Keith Wolgemuth, Ph.D.
LCDR MSC USN
Naval Medical Center, San Diego
This presentation will involve a brief historical perspective of the origin of the current “Auditory Fitness for Working in Noise” or “270 dB Program” mandated by the Bureau of Medicine and Surgery in February of 1998. Information will be presented on how the program was implemented in the San Diego, CA area and at outlying commands in central CA. Summary descriptive statistics will be discussed concerning hearing conservation-patient disposition recommendations in the San Diego program, as well as two or three interesting case studies that highlight both the clinical and personnel issues involved in making such decisions. The presentation will conclude with research recommendations regarding future modifications to this program.
New Advances in Protecting and Restoring the Inner Ear
From The Department of Defense Spatial Orientation Center
Naval Medical Center San Diego
Department of Otolaryngology Suite 200
34520 Bob Wilson Drive
San Diego CA 92134-2200
Authors: Kopke RD, Hoffer ME, Jackson RL, Wolgemuth KS, Wester DC, O’Leary MJ, Henderson D, Van De Water TR Over the past decade significant advances have been made in understanding the molecular mechanisms of inner ear damage due to toxins including excessive noise. Advances have also been made in the areas of drug delivery to the inner ear as well as increased understanding of how the inner ear protects and repairs itself when exposed to damaging stress. This new information has in turn led to progress in the protection, repair and regeneration of inner ear neurosensory structures. This talk will review some of the basic new information regarding the role of toxin and noise- mediated oxidative stress in inner ear damage. Strategies based on mechanistic principles for protection, rescue and regeneration of the inner ear from noise and toxin damage will also be presented, along with specific basic science and clinical examples of each. Future prospects for clinical protection, repair and regeneration will also be discussed.
Identification of Vestibular Schwannomas Through the Hearing Conservation Program: Three Case Presentations
Early identification of retro-cochlear pathology is curtail to the preservation of post-surgical hearing and vestibular function, along with aiding in the reduction of post-surgical complications. Often the first symptom is a unilateral decrease in hearing which can be identified through the Navy’s Hearing Conservation Program. Three Magnetic Resonance Imaging (MRI) and/or surgically confirmed cases are presented, all referred to the Occupational Audiology Service at Naval Medical Center Portsmouth Virginia due to a Significant Threshold Shift (STS) identified during hearing conservation testing. Otologic and audiologic symptoms are discussed.
CDR Bob Rogers, LT Joel Bealer
Naval Medical Center
Portsmouth, VA
LT (sel) James Davis
US Naval Hospital
Yokosuka, Japan