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Gasier H.G.,Naval Submarine Medical Research Laboratory | Fluckey J.D.,Texas A&M University | Previs S.F.,Case Western Reserve University
Nutrition and Metabolism | Year: 2010

Skeletal muscle protein synthesis has generally been determined by the precursor:product labeling approach using labeled amino acids (e.g., [ 13C]leucine or [13C]-, [15N]-, or [ 2H]phenylalanine) as the tracers. Although reliable for determining rates of protein synthesis, this methodological approach requires experiments to be conducted in a controlled environment, and as a result, has limited our understanding of muscle protein renewal under free-living conditions over extended periods of time (i.e., integrative/cumulative assessments). An alternative tracer, 2H2O, has been successfully used to measure rates of muscle protein synthesis in mice, rats, fish and humans. Moreover, perturbations such as feeding and exercise have been included in these measurements without exclusion of common environmental and biological factors. In this review, we discuss the principle behind using 2H2O to measure muscle protein synthesis and highlight recent investigations that have examined the effects of feeding and exercise. The framework provided in this review should assist muscle biologists in designing experiments that advance our understanding of conditions in which anabolism is altered (e.g., exercise, feeding, growth, debilitating and metabolic pathologies). © 2010 Gasier et al; licensee BioMed Central Ltd.

Lee B.C.,Naval Submarine School | Young C.R.,Naval Submarine Medical Research Laboratory
Undersea and Hyperbaric Medicine | Year: 2015

This case report presents a military diver who became dysphoric and lost consciousness during a routine surface- supplied dive. The patient regained consciousness spontaneously, but the physical exam was notable for bilateral ophthalmoplegia. Full eye movement was regained during hyperbaric oxygen (HBO2) therapy, and the patient subsequently made a full recovery. Equipment and dive profile analysis led to the conclusion of hypercapnia and arterial gas embolism as the probable causes of the diver's symptoms. This is a unique case of isolated bilateral ophthalmoplegia presenting in a diving injury. Copyright © 2015 Undersea & Hyperbaric Medical Society, Inc.

Tufts J.B.,University of Connecticut | Chen S.,University of Connecticut | Marshall L.,Naval Submarine Medical Research Laboratory
Journal of the Acoustical Society of America | Year: 2013

Custom-molded earplugs (CMEPs) whose canal segments extend beyond the second bend of the ear canal can provide excellent attenuation but can sometimes be uncomfortable. Attenuation was measured for CMEPs whose canal segments were shortened in 2-mm increments. The within-subjects design permitted illustration of the form of the function relating attenuation to canal segment length for individuals. Reduction of attenuation due to canal segment shortening was generally more pronounced for frequencies ≤1000 Hz. Some regions of the canal segments were more critical than others in maintaining attenuation. The relationship between comfort and canal segment length was not straightforward. © 2013 U.S. Government.

Reini S.A.,Naval Submarine Medical Research Laboratory
Aviation Space and Environmental Medicine | Year: 2010

Cortisol is a stress-response hormone that is important for survivability in fight or flight situations. Hypercortisolism is a state of chronically elevated cortisol levels due to a failure to return to, or maintain baseline levels. It is a condition that is often undiagnosed and can aid in the development of many physiological and psychological health problems. Some of the health ailments associated with hypercortisolism include metabolic syndrome, decreases in bone mineral density, and depression. Chronic stress and sleep deprivation are two common causes of hypercortisolism, both areas of concern within the submarine community. This review discusses the etiology of hypercortisolism and the likelihood of submariner vulnerability to the condition along with health problems associated with it. Lastly, strategies to prevent chronic elevation of cortisol and mitigate the potential health risks associated with the condition are covered. Copyright © by the Aerospace Medical Association, Alexandria, VA.

Gasier H.,Naval Submarine Medical Research Laboratory | Olson C.,Salus Education LLC
Journal of Exercise Physiology Online | Year: 2010

Carbohydrate-protein (CHO-PRO) beverages have been reported to improve endurance performance; however, no studies have been conducted on elite military combatants in a field setting in a fed state. Thus, the primary objective of this study was to evaluate the effects of a CHO-PRO supplement on physical performance and mood in U.S. Air Force Pararescue indoctrination trainees. Eight, healthy U.S. Air Force Pararescue indoctrination trainees completed a double-blind, randomized crossover study. Following a morning meal (592 kcal), subjects completed a 2000 m swim, physically demanding water activities, calisthenics (push-ups, pull-ups, curl-ups and flutter-kicks), a 6.4 km run, and a 400 m exhaustive run. Supplements (600 ml x 5 doses) were provided throughout the study and consisted of a placebo (PLA), an 8.9% carbohydrate solution (CHO), and a 7.22% carbohydrate/1.81% protein solution (CHO-PRO). Times (minutes and seconds) and repetitions were used to assess physical performance, and subjective mood states were determined using the Profile of Mood States Questionnaire (POMS). No differences were observed between the CHO-PRO, CHO, and PLA groups on any of the physical performance measures or mood states. These results suggest that, in the fed state, a CHO-PRO beverage does not enhance physical performance or mood during a series of physically demanding activities lasting < 1 h in duration in U.S. Air Force Pararescue indoctrination trainees.

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