Author: ehgroth

Keat Ghee Ong and Rupak Rajachar Receive Funding

Assistant Professors Keat Ghee Ong (BME) and Rupak Rajachar (BME) have received $146,764 from the US Department of Defense CDMRP for a two-year project, “Remotely Activated, Sub-Micron Vibrating Surfaces for Controlling Infections and Uncontrolled Fibrosis at the Osseointegrated Limb Interfaces.”

Keat G. Ong (Biomedical Engineering) has received $212,727 from the US Department of Defense, Army, Congressionally Directed Medical Research Programs, for a two-year project, “A Wireless Sensor System for Real-Time Measurement of Pressure Profiles at Lower Limb Prostheses to Ensure Proper Fitting.”

Keat Ghee Ong Receives 3M Nontenured Faculty Award

Keat Ghee Ong, an assistant professor in the Department of Biomedical Engineering, has received 3M Nontenured Faculty Awards in 2009 and 2010 to support his research on wireless implantable sensor technologies. The award, which is nominated by 3M researchers working on research topics that are of interest to 3M, is currently sponsored by Jim Vanous of SEMS Electronics Applications group.

First in vivo Measurement of Differential Motion in the Guinea Cochlea

Monday, October 4
211 Chemical Sciences Building
3:00 pm

Presenter: Niloy Choudhury, Ph.D., Department of Biomedical Engineering, Oregon Health & Science University, Portland, Oregon

Abstract: Auditory response in mammals depends upon an amplifying mechanism which hypothetically uses forces from outer hair cell (OHC) motility to enhance sound-induced vibration of the organ of Corti in the cochlea. Differential motion among key structures in this organ and proper timing of OHC force generation are essential to this hypothesis.  An optical coherence tomography (OCT) system was designed and built to image the microstructures and measure mechanical vibrations at different cellular structures in the guinea pig cochlea.  The traditional OCT system was modified to  allow measure of nanometer scale vibration motion.  The new scheme  allows quantitative values for phase and amplitude vibration in the presence of bulk animal motion.  The engineering of the system as well as the first ever  in vivo measurements of differential motion of two functionally important structures in the organ of Corti, the basilar membrane and reticular lamina, will be presented.  Results show that the reticular lamina vibrates at a greater magnitude than the basilar membrane and has a significant phase lead.  Similar phase relation between OHC receptor potentials and basilar membrane motion were observed. These results demonstrate that a powerful enhancement of vibration occurs at the apical surface of sensory hair cells and that  OHC force generation is optimally timed for counteracting viscosity-related energy loss.

RNA Splicing and Polyadenylation Control in Retroviruses: Implications for Cellular Control

September 3, 2010

U113 M&M

2:00 – 3:00 pm

Presenter: Dr. Mark McNally, Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, Milwaukee

Abstract: Characterizing unique virus-host interactions is key to understanding pathogenesis and developing therapeutics to block the virus life cycle. Because of their intimate associations with host cells, viruses have also been exploited as tools for studying many basic cellular processes, including RNA processing. For retroviruses, control of splicing and polyadenylation is an important aspect of the replication cycle. Splicing of retroviral primary transcripts must be controlled since high levels of unspliced RNA are needed as mRNA, and for incorporation as genomes into progeny virions. Polyadenylation control is important because failure to use the viral polyadenylation site results in read-through transcripts that extend into downstream genomic sequences; this is the basis for oncogenic transformation and the ability of retroviruses to acquire host cell sequences through oncogene capture. We are studying viral cis elements and host trans-acting factors required for proper RNA processing and replication of Rous sarcoma virus (RSV), not only to further an understanding of virus replication but to provide insights into host cell RNA processing regulation. Our work focuses in part on a novel RNA processing control element, the negative regulator of splicing (NRS), that contributes to the accumulation of genome-length RNA by acting as a pseudo 5’ss to repress splicing. We continue to study a host factor, hnRNP H, that is required for high-efficiency binding of U11 snRNP (a splicing factor in the ‘minor’ splicing pathway that binds to 5′ splice sites) to the NRS, with an eye towards deeper understanding of its role in alternative splicing of cellular genes. Interestingly, the NRS is also required for proper polyadenylation of viral RNAs, and we have made the novel finding that a class of splicing factors (SR proteins) mediates stimulation of polyadenylation by the NRS in a position-dependent manner; this observation suggests that some cellular mRNAs might use a similar mechanism of polyadenylation control. Thus, the RSV system has provided a powerful tool to dissect novel cellular mechanisms of RNA processing regulation.