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Leonard P. Rybak, MD, PhD
Division of Otolaryngology - Head and Neck Surgery




Research Interests/Areas of Expertise:


Dr. Leonard P. Rybak, is a professor and ear, nose and throat specialist whose general otolaryngology practice focuses on sinus disease and obstructive sleep apnea. Dr. Rybak received his medical degree from the Medical College of Wisconsin-Milwaukee and completed his internship at Hennepin County Medical Center in Minneapolis. He completed a residency in otolaryngology and also obtained a PhD at the University of Minnesota-Minneapolis.

Dr. Rybak served as an Assistant Professor of Otolaryngology at the University of Minnesota prior to coming to the SIU School of Medicine. Dr. Rybak's professional affiliations include the American College of Surgeons, and the American Academy of Otolaryngology - Head and Neck Surgery. Locally, he is a member of the Sangamon County Medical Society and of various committees at St. John’s Hospital and the SIU School of Medicine. He serves as president of the Sangamon County Chapter of the Society for Neuroscience.

As a clinician and surgeon, Dr. Rybak's special interests include general otolaryngology and sleep apnea. Known both nationally and internationally for his research in the field of otolaryngology, Dr. Rybak has published and presented numerous articles and chapters dealing with various aspects of ear, nose and throat diseases. He is certified by the American Board of Otolaryngology.

For more information or to schedule an appointment with Dr. Rybak, please call 217-545-8000.

Toxicology Lab

August 21, 2014 Press Release

SIU Researcher Receives NIH Grant to Study Chili Pepper Component to Reduce Hearing Loss

A physician researcher at Southern Illinois University (SIU) School of Medicine in Springfield has been awarded a five-year federal grant from the National Institute of Deafness and Communication Disorders (NIDCD) of the National Institutes of Health to continue his studies of how to reduce hearing loss in cancer patients undergoing chemotherapy treatment. The current research project will examine whether capsaicin, a component of hot chili peppers, can reduce hearing loss and kidney damage if given prior to or after a dose of cisplatin, an anti-cancer drug frequently used for chemotherapy.

Dr. Leonard Rybak, professor emeritus of surgery in the Division of Otolaryngology Head and Neck Surgery and SIUC distinguished scholar, is the principal investigator for the project. The study is a continuation of an existing grant that has been funded for 17 years, to study the mechanisms and prevention of cisplatin ototoxicity. The grant has a total budget of $1,549,269.

“Cisplatin has been the most effective anti-tumor drug since the 1970’s,” Rybak said. “Through our research, we’re trying to make it less toxic without making it less effective.” Rybak’s previous research has shown that cisplatin causes reactive oxygen species (ROS) that damage the inner ear, causing permanent hearing loss. The research has identified several different pathways that can be targeted to decrease cisplatin induced hearing loss without compromising its tumor killing capacity.

Over the previous period of funding, Rybak studied several antioxidants and found that in animal models, these drugs protect against cisplatin-induced hearing loss and kidney damage. However, some experts are concerned that the antioxidants may interfere with cisplatin’s effectiveness as a cancer treatment. For that reason, Rybak’s laboratory is investigating potentially safer alternatives, such as capsaicin. Otolaryngology residents and pharmacology graduate students participated in these studies.

The study will determine the smallest doses of capsaicin possible that will prevent hearing loss yet still allow cisplatin to be effective in the treatment of tumors. The results of the research may lead to cancer treatment with fewer negative side effects, like hearing loss and kidney damage.

The importance of these findings underscores the use of readily available natural products in the prevention of toxic effects of chemotherapy. These findings could easily be translated to humans for clinical use in the near future.
Rybak’s research team at SIU includes Vickram Ramkumar, Ph.D., Debashree Mukherjea, Ph.D., Kelly Sheehan and Puspanjali Bhatta. He will also use a consultant, Sridar Chittur, Ph.D., director of the Center of Functional Genomics at the University of Albany, New York.

Rybak, who also is a member of the Simmons Cancer Institute, joined the SIU faculty in 1981. He completed his doctorate degree as well as a residency in otolaryngology at the University of Minnesota (1979). Rybak earned his medical degree at the Medical College of Wisconsin (1973). He earned his bachelor’s degree at the St. Louis College of Pharmacy (1969). He is board certified in otolaryngology. Since 1994, he's delivered 31 presentations and 40 published peer-reviewed journal articles on cisplatin-induced ototoxicity. Rybak has also mentored five medical students and one Ph.D. candidate who all performed research on cisplatin ototoxicity.

Compounds Investigated

Electrophysiological Measures

Morphological Measures

Biochemical Measures

In collaboration with:

Vickram Ramkumar, PhD, Department of Pharmacology

Full CV download here

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