1. The dynamics of coated and free microbubbles in the presence of ultrasound to enhance drug delivery*
Nima Mobadersany, George Washington University, Department of Mechanical and Aerospace Engineering
2. Computing wave responses in solids and fluid caused by an earthquake*
Bruno Peruqui Guidio and Chanseok Jeong, The Catholic University of America, Department of Civil Engineering
3. Innervation and plasticity of the olivocochlear system*
Dillan F. Villavisanis1, Katrina M. Schrode1, Omobolade Odedoyin1, Matthew Xu-Fredman2 and Amanda M. Lauer1
1 Johns Hopkins University School of Medicine, Center for Hearing and Balance, Department of Otolaryngology – Head & Neck Surgery
2 Department of Biological Sciences, University at Buffalo
3. Characterization of damping properties in 3D printed materials*
Jenna Gietl, Diego Turo and Joseph Vignola, The Catholic University of America, Department of Mechanical Engineering
4. The various investigations and causes of ambient noise in ocean*
Laurie Wei, The Catholic University of America, Department of Mechanical Engineering
ABSTRACTS:
The dynamics of coated and free microbubbles in the presence of ultrasound to enhance drug delivery
Student presenter: Nima Mobadersany
Department of Mechanical and Aerospace Engineering, School of Engineering, the George Washington University
Ultrasound waves are pressure waves capable of transporting energy into the body as they are absorbed relatively little by tissues. Their non-invasive, safe and painless transmission through the skin makes them suitable for use in drug delivery and gene therapy applications. Ultrasound in the presence of microbubbles facilitates transportation of drugs. These FDA approved encapsulated microbubbles (contrast agents) were initially developed for enhancing the contrast of ultrasound image. Contrast agents can carry and transport drugs or genes to the desired site through injection inside the bloodstream. They consist of a gas core encapsulated by a layer of protein or lipid to stabilize them against dissolution. Ultrasound wave excites the microbubbles making them implode (collapse) resulting in the release of drug/gene into the desired tissue. In addition to the role of microbubble as a drug carrier, in this study we aim to show that the collapse of microbubble forms or even increases the size of the small pores in the cell membrane. This can allow the transfer of DNA/RNA into the cell for gene therapy. It can also help to facilitate the uptake of drugs and large molecules into the cells. It can even help delivering drugs to cells with tight junctions like blood brain barrier by increasing the permeability of the cells. We also show that not only the collapse of these bubbles can help perforating the membranes, but their repeated pulsation also creates shear stress on membranes and perforates them. These bubbles will pulsate repeatedly if the excitation ultrasound pressure is not high enough to make them implode.
Innervation and Plasticity of the Olivocochlear System
Dillan F. Villavisanis1 (Undergraduate Student, dvillav1@jhu.edu), Katrina M. Schrode1,
Omobolade Odedoyin1, Matthew Xu-Friedman2, Amanda M. Lauer1
1Department of Otolaryngology – Head & Neck Surgery, Center for Hearing and Balance, Johns
Hopkins University School of Medicine
2Department of Biological Sciences, University at Buffalo
Background
Hair cells and afferent neurons in the organ of Corti are contacted by a network of efferent neurons
that send information from the brain back to the cochlea to modulate afferent activity. The efferent
(olivocochlear) system is comprised of the medial olivocochlear system (MOCS), which innervates
the outer hair cells (OHCs), and the lateral olivocochlear system (LOCS), which innervates the
auditory nerve fibers contacting the inner hair cells (IHCs). We investigated the effects of exposure
to acute loud noise and chronic environmental noise on olivocochlear synapses using an antibody
to label synaptic vesicle protein 2 (sv2).
Methods
CBA/CaJ mice were housed in moderate environmental acoustic conditions or under normal
acoustic conditions. A subset of the former group was restored to normal acoustic conditions
following the moderate environmental acoustic conditions. Mouse cochleae were dissected into
five or six flat half-turns and standard immunohistochemistry protocols were used to visualize
hair cells (rabbit anti-myo6 and Alexa Fluor 568 Goat anti-Rabbit) and sv2-labeled synaptic
vesicles (mouse anti-sv2 and Alexa Fluor 488 Goat anti-Mouse). Images of cochlear half-turns
were taken at 10x magnification to identify frequency specific points at half-octave intervals
using the Measure Line ImageJ plugin. Confocal images at specific frequencies were taken at
63x magnification by creating maximum intensity projections from z-stacks. Density of sv2
labeling from confocal images was quantified for each hair cell by counting each type of hair cell
(IHCs and OHCs) and dividing by the total associated area of sv2 labeling.
Results
There was no statistically significant difference between sv2 density for the MOCS between
mice housed in moderate acoustic conditions and those housed in standard housing. However,
a statistically significant increase was found in the mice housed under moderate acoustic
conditions for the LOCS at high frequency regions. Mice exposed to moderate environmental
acoustic conditions and then restored to normal acoustic conditions demonstrate an increase in
LOC sv2 density at high frequencies that is not completely restored.
Conclusions
The increase of sv2 density in LOC neurons in mice exposed to moderate noise compared to
mice exposed to standard housing conditions suggests a protective upregulation of the efferent
system against moderate, chronic noise exposure. The increase in sv2 density despite
restoration to normal acoustic conditions following the moderate, chronic noise exposure may
suggest that the LOCS does not have a high degree of plasticity.
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