New Bolton Center Kennett Square, PA
Emergencies & Appointments:
Ryan Hospital Philadelphia, PA


Assistant Professor, Pathobiology, University of Pennsylvania School of Veterinary Medicine

Assistant Director, Clinical Care, University of Pennsylvania University Laboratory Animal Resources

Diplomate, American College of Laboratory Animal Medicine (DACLAM)

Research Areas: Laboratory Animal Medicine,
PubMed Link
Contact Information:
176 EG Old Vet Quadrangle
3800 Spruce Street

As a diplomat of the American College of Laboratory Animal Medicine, my clinical specialty is in the care and use of animals used in biomedical research. While most of my research interests in this field revolve around mice, I have extensive experience providing care for all of the species commonly used in research.

I currently have two areas of research interest. First is in refining and improving the clinical care of laboratory mice. My goal is to work to improve the diagnostic and therapeutic options for mice. My second area of collaboration extends back to my work in the fields of skeletal and smooth muscle contractility.

Chang S, Gomes CM, Hypolite JA, Marx J, Alanzi J, Zderic SA, Malkowicz B, Wein AJ, Chacko S. Detrusor overactivity is associated with downregulation of large-conductance calcium- and voltage-activated potassium channel protein Am J Physiol Renal Physiol. 298: F1416-23, 2010.

Kraemer WJ, Nindl BC, Volek JS, Marx JO, Gotshalk LA, Bush JA, Welsch JR, Vingren JL, Spiering BA, Fragala MS, Hatfield DL, Ho JY, Maresh CM, Mastro AM, Hymer WC. Influence of oral contraceptive use on growth hormone in vivo bioactivity following resistance exercise: Responses of molecular mass variants. Growth Horm IGF Res. 18: 238-44, 2008.

Marx, J.O., Olsson, M.C., and Larsson, L. Scaling of skeletal muscle shortening velocity in mammals representing a 100,000-fold difference in body size. Pflugers Archives: European Journal of Physiology 452: 222-30, 2006.

Stanton MC, Austin JC, Delaney DP, Gosfield A, Marx JO, Zderic SA, Chacko S, Moreland RS. Partial bladder outlet obstruction selectively abolishes protein kinase C induced contraction of rabbit detrusor smooth muscle. Journal of Urology 176: 2716-21, 2006.

Miles, M.P., Kraemer, W.J., Nindl, B.C., Grove, D.S., Leach, S.K., Dohi, K., Marx, J.O., Volek, J.S., and Mastro, A.M. Strength, workload, anaerobic intensity and the immune response to resistance exercise in women. Acta Physiologica Scandinavica 178: 155-63, 2003.

Miles, M.P., Kraemer, W.J., Grove, D.S., Leach, S.K., Dohi, K., Bush, J.A., Marx, J.O., Nindl, B.C., Volek, J.S., and Mastro, A.M. Effects of resistance training on resting immune parameters in women. European Journal of Applied Physiology 87: 506-8, 2002.

Marx, J.O., Kraemer, W.J., Nindl, B.C., and Larsson, L.G. The effect of aging on skeletal muscle myosin heavy chain mRNA. Journals of Gerontology: Biological Sciences 57: 232-38, 2002.

Miles, M.P., Mackinnon, L.T., Grove, D.S., Williams, N.I., Bush, J.A., Marx, J.O., Kraemer, W.J., and Mastro, A.M. The relationship of natural killer cell counts, perforin mRNA and CD2 expression to post-exercise natural killer cell activity in humans. Acta Physioliogica Scandinavica 17: 317-25, 2002.

Marx, J.O., S.E. Gordon, N.H. Vos, B.C. Nindl, A.L. Gomez, J.S. Volek, J. Pedro, K. Häkkinen, N.A. Ratamess, S.A. Mazzetti, R.U. Newton, and. W.J. Kraemer. Effect of alkalosis on plasma epinephrine responses to high intensity cycle exercise. European Journal of Applied Physiology 87: 72-77, 2002.

Larsson, L., Yu, F., Hook, P., Ramamurthy, B., Marx, J.O., and Pircher, P. Effects of aging on regulation of muscle contraction at the motor unit, muscle cell and molecular levels. International Journal of Sport Nutrition and Exercise Metabolism 11: s26-s22, 2001.

Kraemer, W.J., Staron, R.S., Gordon, S.E., Volek, J.S., Koziris, L.P., Duncan, N.D., Nindl, B.C., Gomez, A.L., Marx, J.O., Fry, A.C., Murray, J.D., and Hikida, R.S. The effect of 10 days spaceflight on the shuttle Endeavor on predominantly fast-twitch muscles in the rat. Journal of Histochemistry and Cell Biology 114: 349-55, 2000.

DVM (Veterinary Medicine) NYSCVM, 1991

PhD (Kinesiology) The Pennsylvania State University, 2001

BS (Animal Science) Cornell University, 1988