Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Lauren B. Priddy

Committee Member

Raj K. Prabhu

Committee Member

Steven H. Elder

Committee Member

Raheleh Miralami

Committee Member

Keith E. Tansey

Date of Degree

8-6-2021

Original embargo terms

Visible to MSU only for 1 year

Document Type

Dissertation - Campus Access Only

Major

Biomedical Engineering

Degree Name

Doctor of Philosophy

College

James Worth Bagley College of Engineering

Department

Department of Agricultural and Biological Engineering

Abstract

Low back pain is a leading cause of disability and is associated with whole-body vibration exposure in industrial workers and military personnel. The pathophysiological mechanisms by which whole-body vibration causes low back pain have been studied in vivo, but there is little data that improve diagnosis of low back pain. The overall objective of this research was to elucidate diagnostic biomarkers associated with whole-body vibration. Hence, a rat model for vibration-induced inflammatory responses was developed. Von Frey filaments were used to determine the withdrawal threshold of the hind paw as a surrogate behavioral marker for pain. The concentration of nerve growth factor in the serum was measured every four days using an assay as a potential diagnostic biomarker for low back pain. In the first study, whole-body vibration was applied using a modified commercially available device at 8 or 12 Hz every other day for two weeks, following which animals recovered for one week. At the conclusion of the study, intervertebral discs were graded histologically for degeneration. The nerve growth factor concentration increased threefold in the 8 Hz group and twofold in the 12 Hz group and returned to baseline by the end of the recovery period for 12 Hz, but not 8 Hz. Mechanical sensitivity appeared to change over time due to habituation and not any effect of vibration and was inconclusive. There was no difference in intervertebral disc degeneration scores between groups. In the second study, rats were vibrated at 8 Hz every other day for two or four weeks. The concentrations of nine cytokines were determined in the longissimus muscle, spleen, and thymus using a multiplex assay. These cytokines were ranked according to their ability to differentiate vibrated and non-vibrated animals, and classification models were compared. Nerve growth factor serum concentration peaked on day 13, then returned to baseline on day 17. The withdrawal threshold in vibrated animals decreased throughout the study indicating greater sensitivity to the stimulus, a surrogate for increased pain. Several longissimus muscle and spleen cytokines were important in distinguishing vibrated animals from non-vibrated, while thymus cytokines and weeks of exposure were not significant.

Sponsorship

US Army ERDC Contract No. W912HZ-17-C-0021 The Graduate School at Mississippi State University The Office of the Provost and the Executive Vice President at Mississippi State University

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