Assistant Professor, Exercise Science
BS: University of California, Los Angeles, 1995
MA: Pepperdine University, 2000
PhD: New Mexico State University, 2006
I am interested in determining how much activity is required to maintain near normal hindlimb muscle properties after a spinal cord injury. In my first experiments, my colleagues and I used an implantable microstimulator that is controlled by an external unit to deliver known amounts of electromechanical activity to determine the dose-response curve of electromechanical stimulation and its effect on muscle mass. We then looked at a variety of genes known to regulate muscle hypertrophy and atrophy using Western blot analyses and semi-quantitative RT-PCR experiments. Second, I am interested in determining how loss in muscle force and increased muscle fatigability commonly observed after a spinal cord injury impacts neural control of locomotion. I am currently carrying out two investigations to address this question. In the first experiment, we are blocking the expression of myostatin, a gene that inhibits skeletal muscle differentiation, and assess whether preventing muscle atrophy and inducing hypertophy can improve the force generating capacity in the hindlimb muscles after a complete spinal cord transection to improve locomotor function, i.e., full weight-bearing stepping. In the second experiment we are overexpressing PPARd, a transcription factor that increases the fatigue resistance properties in predominantly fast-twitch glycolytic muscles after spinal cord injury to determine whether improving the fatigue properties of the affected hindlimb muscles are correlated to improved locomotor function. Third, I am interested in mapping the spinal circuitry involved in standing and stepping after a spinal cord injury. We are using various retrograde labeling techniques to label muscle-specific motoeneurons and their associated last order interneurons. We are also using immunohistochemistry to characterize these interneurons on the basis of their neurotransmitter properties. The successful completion of these studies will have large implications for future interventions, not only for spinal cord injured subjects, but also for individuals with a number of other neuromotor diseases.