David G Besselsen

David G Besselsen

Adjunct Associate Professor, Animal and Comparative Biomedical Sciences
Associate Research Scientist, BIO5 Institute
Member of the Graduate Faculty
Veterinary Specialist
Primary Department
Contact
(520) 626-6702

Research Interest

Research Interest
David Besselsen, DVM, PhD, is the Director of University Animal Care (UAC), the Attending Veterinarian. He is a board-certified veterinary specialist (Diplomate) in the American College of Laboratory Animal Medicine and the American College of Veterinary Pathology, and served as Interim Dean for the College of Veterinary Medicine from 2017-2019. In addition to his administrative and service responsibilities, Dr. Besselsen is actively engaged in research through the provision of comparative pathology support for rodent models and oversight of the gnotobiotic mouse service. He has directed UAC Pathology Services since his arrival in 1995 and has over 80 peer-reviewed publications. UAC Pathology Services provides diagnostic and comparative pathology support for the research animals and research animal facilities at the University of Arizona. Capabilities include hematology, blood chemistry, necropsy, histologic preparation and interpretation, and others.

Publications

Watson, J. M., Marion, S. L., Rice, P. F., Bentley, D. L., Besselsen, D. G., Utzinger, U., Hoyer, P. B., & Barton, J. K. (2014). In vivo time-serial multi-modality optical imaging in a mouse model of ovarian tumorigenesis. Cancer Biology and Therapy, 15(1), 42-60.
BIO5 Collaborators
Jennifer Kehlet Barton, David G Besselsen

Abstract:

Identification of the early microscopic changes associated with ovarian cancer may lead to development of a diagnostic test for high-risk women. In this study we use optical coherence tomography (OCT) and multiphoton microscopy (MPM) (collecting both two photon excited fluorescence [TPEF] and second harmonic generation [SH G]) to image mouse ovaries in vivo at multiple time points. We demonstrate the feasibility of imaging mouse ovaries in vivo during a longterm survival study and identify microscopic changes associated with early tumor development. These changes include alterations in tissue microstructure, as seen by OCT, alterations in cellular fluorescence and morphology, as seen by TPEF, and remodeling of collagen structure, as seen by SH G. These results suggest that a combined OCT-MPM system may be useful for early detection of ovarian cancer. © 2014 Landes Bioscience.

Barton, J., Hariri, L. P., Qiu, Z., Tumlinson, A. R., Besselsen, D. G., Gerner, E. W., Ignatenko, N. A., Povazay, B., Hermann, B., Sattmann, H., McNally, J., Unterhuber, A., Drexler, W., & Barton, J. K. (2007). Serial endoscopy in azoxymethane treated mice using ultra-high resolution optical coherence tomography. Cancer biology & therapy, 6(11).
BIO5 Collaborators
Jennifer Kehlet Barton, David G Besselsen

Optical coherence tomography (OCT) is a minimally invasive, depth-resolved imaging tool that can be implemented in a small diameter endoscope for imaging mouse models of colorectal cancer (CRC). In this study, we utilized ultrahigh resolution (UHR) OCT to serially image the lower colon of azoxymethane (AOM) treated A/J mouse models of CRC in order to monitor the progression of neoplastic transformations and determine if OCT is capable of identifying early disease.

Barton, J., Hariri, L. P., Tumlinson, A. R., Wade, N. H., Besselsen, D. G., Utzinger, U., Gerner, E. W., & Barton, J. K. (2007). Ex vivo optical coherence tomography and laser-induced fluorescence spectroscopy imaging of murine gastrointestinal tract. Comparative medicine, 57(2).
BIO5 Collaborators
Jennifer Kehlet Barton, David G Besselsen

Optical coherence tomography (OCT) and laser-induced fluorescence (LIF) spectroscopy each have clinical potential in identifying human gastrointestinal (GI) pathologies, yet their diagnostic capability in mouse models is unknown. In this study, we combined the 2 modalities to survey the GI tract of a variety of mouse strains and ages and to sample dysplasias and inflammatory bowel disease (IBD) of the intestines. Segments (length, 2.5 cm) of duodenum and lower colon and the entire esophagus were imaged ex-vivo with combined OCT and LIE We evaluated 30 normal mice (A/J and 10- and 21-wk-old and retired breeder C57BL/6J) and 10 mice each of 2 strains modeling colon cancer and IBD (Apc(Min) and IL2-deficient mice, respectively). Histology was used to classify tissue regions as normal, Peyer patch, dysplasia, adenoma, or IBD. Features in corresponding OCT images were analyzed. Spectra from each category were averaged and compared via Student t tests. OCT provided structural information that led to identification of the imaging characteristics of healthy mouse GI. With histology as the 'gold standard,' we developed preliminary image criteria for early disease in the form of adenomas, dysplasias, and IBD. LIF characterized the endogenous fluorescence of mouse GI tract, with spectral features corresponding to collagen, NADH, and hemoglobin. In the IBD sample, LIF emission spectra displayed potentially diagnostic peaks at 635 and 670 nm, which we attributed to increased porphyrin production by bacteria associated with IBD. OCT and LIF appear to be useful and complementary modalities for ex vivo imaging of mouse GI tissues.

Hahn, T., Bradley-Dunlop, D. J., Hurley, L. H., Von-Hoff, D., Gately, S., Mary, D. L., Lu, H., Penichet, M. L., Besselsen, D. G., Cole, B. B., Meeuwsen, T., Walker, E., & Akporiaye, E. T. (2011). The vitamin E analog, alpha-tocopheryloxyacetic acid enhances the anti-tumor activity of trastuzumab against HER2/neu-expressing breast cancer. BMC cancer, 11.
BIO5 Collaborators
David G Besselsen, Laurence Hurley

HER2/neu is an oncogene that facilitates neoplastic transformation due to its ability to transduce growth signals in a ligand-independent manner, is over-expressed in 20-30% of human breast cancers correlating with aggressive disease and has been successfully targeted with trastuzumab (Herceptin®). Because trastuzumab alone achieves only a 15-30% response rate, it is now commonly combined with conventional chemotherapeutic drugs. While the combination of trastuzumab plus chemotherapy has greatly improved response rates and increased survival, these conventional chemotherapy drugs are frequently associated with gastrointestinal and cardiac toxicity, bone marrow and immune suppression. These drawbacks necessitate the development of new, less toxic drugs that can be combined with trastuzumab. Recently, we reported that orally administered alpha-tocopheryloxyacetic acid (α-TEA), a novel ether derivative of alpha-tocopherol, dramatically suppressed primary tumor growth and reduced the incidence of lung metastases both in a transplanted and a spontaneous mouse model of breast cancer without discernable toxicity.

Ball, C. L., Daniel, S. G., Besselsen, D. G., Hurwitz, B. L., & Doetschman, T. C. (2017). Functional changes in the gut microbiome contribute to Transforming Growth Factor β-deficient colon cancer. mSystems, 2(5), 1-17.
BIO5 Collaborators
David G Besselsen, Thomas C Doetschman, Bonnie L Hurwitz