Penn Comprehensive Neuroscience Center

Faculty Members
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David M. Raizen, MD, PhD

Assistant Professor of Neurology
Member, Center for Sleep and Circadian Neurobiology, University of Pennsylvania School of Medicine
Member, Mahoney Institute of Neurological Sciences, University of Pennsylvania
Member, Institute for Translational Medicine and Therapeutics, University of Pennsylvania
Member, Chronobiology program, University of Pennsylvania
Department: Neurology

Contact information
Dept Neurology
462 Stemmler Hall
415 Curie Blvd
Philadelphia, PA 19104-4283
Graduate Group Affiliations
Education:
BA (Biochemistry)
University of Texas at Austin, 1989.
MD (Medicine)
University of Texas Southwestern, 1997.
PhD (Neuroscience)
University of Texas Southwestern, 1997.
Post-Graduate Training
Intern in Medicine, Hospital of the University of Pennsylvania, 1998-1999.
Resident in Neurology, Hospital of the University of Pennsylvania, 1999-2002.
Fellow in Sleep Medicine, University of Pennsylvania School of Medicine, 2002-2004.
Certifications
American Board of Psychiatry and Neurology (Recertified 2013), 2003.
American Board of Sleep Medicine, 2005.
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Description of Research Expertise

Research Interests
The regulation and function of sleep

Key Words: sleep, ecdysis, molting, behavior, amyloid, neuropeptides

Description of Research
Quiescent behavioral states are universal to the animal world with the most famous and mysterious of these being sleep. Despite the fact that we spend one third of our life sleeping, and despite the fact that all animals sleep, the core function of sleep remains a mystery. In addition, the molecular basis underlying sleep/wake regulation is poorly understood.

We use C. elegans as a model system to address these questions. C. elegans offers many experimental advantages including powerful genetic tools as well as a simple neuroanatomy.

Growth of C. elegans from an embryo to an adult is punctuated by four molts, during which the animal secretes a new cuticle and sheds its old one. Prior to each molt the worm has a quiescent behavioral state called lethargus. Lethargus has several similarities to sleep including rapid reversibility to strong stimulation, increased sensory arousal threshold, and homeostatic regulation.

In addition to larval sleep, C. elegans also sleeps during the adult stage, after exposure to an environment that induces cellular stress.


Molecular genetic similarity between C. elegans sleep and sleep in other animals is demonstrated by the identification of signaling pathways that regulate C. elegans sleep in the similar fashion to their regulation of sleep in mammals and arthropods. We have identified new sleep regulators in C. elegans and are currently studying how and in which cells these regulators function.

By studying the purpose and genetic regulation of nematode sleep, we hope to identify additional novel sleep regulators, and to gain insight into why sleep had evolved, a central biological mystery.

Rotation projects
Please see David about possible projects.

Description of Clinical Expertise

Sleep disorders: In particular disorders of sleep regulation and restless leg syndrome.

Selected Publications

Julia B. George-Raizen, Keith R. Shockley, Nicholas F. Trojanowski, Annesia L. Lamb, and David M. Raizen: Dynamically-expressed prion-like proteins form a cuticle in the pharynx of Caenorhabditis elegans. Biology Open (article featured on the journal cover) 3(11), November 2014.

Nelson MD, Lee KH, Churgin MA, Hill AJ, Van Buskirk C, Fang-Yen C,and Raizen DM: FMRFamide-like FLP-13 neuropeptides promote quiescence following heat stress in Caenorhabditis elegans. Current Biology (Article discussed in Nature Neuroscience Reviews) 24(20): 2406-2410, October 2014.

Hill1 AJ,Mansfield R, Lopez JMNG, Raizen DM,and Van Buskirk C: Cellular Stress Induces a Protective Sleep-like State in C. elegans. Current Biology 24(20): 2399-2405, October 2014.

Nagy S, Raizen DM*, Biron D. *Corresponding Author: Measurements of behavioral quiescence in Caenorhabditis elegans. Methods 68(3): 500-507, August 2014.

Ryu MH, Kang IH, Nelson MD, Jensen TM, Lyuksyutova AI, Siltberg-Liberles J, Raizen DM, Gomelsky M.: Engineering adenylate cyclases regulated by near-infrared window light. Proc Natl Acad Sci U S A. 111(28): 10167-72, July 2014.

Yuan J, Raizen DM, Bau HH.: Gait synchronization in Caenorhabditis elegans. Proc Natl Acad Sci U S A. 111(19): 6865-70, May 2014.

Trojanowski NF, Padovan-Merhar O, Raizen DM*, Fang-Yen C. *Corresponding author: Neural and genetic degeneracy underlies Caenorhabditis elegans feeding behavior. J Neurophysiol 112(4): 951-61, May 2014.

Yu CC, Raizen DM, Fang-Yen C: Multi-well imaging of development and behavior in Caenorhabditis elegans. Journal of Neuroscience Methods 223: 35-39, February 2014.

Davis EM and Raizen DM: Prolonging apneas in a hospitalized patient – a potential harm of routine medical therapy. Annals of the American Thoracic Society in press, 2014.

Belfer SJ,Chuang HS, Freedman BL, Yuan J, Norton M, Bau HH, and Raizen DM: Caenorhabditis-in-Drop array for monitoring C. elegans quiescent behavior. Sleep 36(5): 689-698G, May 2013.

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Last updated: 11/13/2014
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