Bioengineering Seminar Schedule, Spring 2009
NO SEMINAR
Friday, January 16, 2009, 12:00 - 1:00 pm, Room 210 Hallowell Building, CG624E Hershey
NO SEMINAR
Friday, January 23, 2009, 12:00 - 1:00 pm, Room 210 Hallowell Building, CG624E Hershey
"Humanitarian Engineering and Social Entrepreneurship: Opportunities for Bioengineers"
Khanjan Mehta, Electronic and Computer Services for the College of Engineering, Penn State University
Friday, January 30, 2009, 12:00 - 1:00 pm, Room 210 Hallowell Building, CG624E Hershey
Abstract
Students from various colleges across Penn State have been working collaboratively on various technology-based social entrepreneurial ventures in East Africa and other regions. One such venture is Mashavu: Networked Health Solutions for the Developing World. There is one doctor for every 50,000 people in East Africa compared to one doctor for every 390 people in the United States. It costs a significant amount of time and money to consult a doctor and whether to even consult a doctor is a critical decision. Mashavu enables medical professionals around the world to connect with patients in the developing world using modern technology and communications infrastructure. Trained operators at Mashavu stations in developing communities collect essential medical information including weight, body temperature, lung capacity, blood pressure, photographs, stethoscope rhythms, basic hygiene and nutrition information for each patient on a regular basis. Web servers aggregate this information from various Mashavu stations over a cell-phone link and d provide it on a web-based portal. Medical professionals can view the patient’s information and respond to the patient and the nearest doctor(s) with their recommendations. Validation efforts prove that numerous entities are willing to purchase Mashavu stations. They can charge customers a small fee, thereby making Mashavu economically sustainable and creating an additional revenue stream.
Approximately eighty students and seven faculty mentors from various disciplines are engaged in the design of the Mashavu system. The design of the ultra inexpensive biomedical devices based on virtual instrumentation is being done in the BIOE 401 class. This seminar will focus on the Mashavu vision and the myriad opportunities for bioengineers to create sustainable value in developing countries.
TBD
Friday, February 6, 2009, 12:00 - 1:00 pm, Room 210 Hallowell Building, CG624E Hershey
"Anomalous Diffusion in MRI Expressed Through Fractional Order Differential Operators in the Bloch-Torrey Equation"
Richard Magin, University of Illinois - Chicago
Friday, February 13, 2009, 12:00 - 1:00 pm, Room 210 Hallowell Building, CG624E Hershey
Abstract
Diffusion weighted MRI is used clinically to detect and characterize neurodegenerative, malignant and ischemic diseases. The correlation between developing pathology and localized diffusion relies on diffusion-weighted pulse sequences that probe biophysical models of molecular diffusion. Several recent studies have investigated the so-called anomalous diffusion model where a measure of tissue complexity is introdued ad hoc. In this seminar, I will describe an alternative model derived using fractional order space and time derivatives in the Bloch-Torrey equation. Fractional order dynamics were observed to fit the signal attenuation in difffusion-weighted images obtained from Sephadex gels, human articular cartilage and human brain. Future developments of this approach may be useful for classifying the anomalous diffusion in tissues with developing pathology.
“Novel Tools for Quantifying the Dynamic Effects of Phenotypic Plasticity and Mechanobiological Stimuli in Tumor Progression”
Zoe Demou, Northwestern University
Friday, February 16, 2009, 11:00am - 12:00, Room 210 Hallowell Building, CG624E Hershey
Abstract
Although phenotypic plasticity and dysregulated biological and mechanical stimuli are considered to promote the spreading of cancer, the exact mechanisms and a cure remain elusive. This seminar summarizes the systems I have developed to model key mechanobiological phenomena in solid tumors in order to measure their effect in invasion, metastasis, and angiogenesis. (A) The first ever fully automated platform for tracking cells in three-dimensional (3D) tissue analogs was combined with a novel statistical analysis of the cell trajectories. This system identifies cell subpopulations according to their distinct abilities for migration and invasion and is ultimately useful as a screening tool for cell motility, invasion and for drugs that attenuate these processes. (B) 3D cell tracking also revealed that defects in collagen polymerization differentially enhance the morphodynamic activity and promote motility and invasion in breast cancer cells. (C) The first ever application of laser capture microdissection (LCM) in living 3D cell cultures revealed that melanoma cells capable of vasculogenic mimicry (formation of vascular-like networks) possess a self-sustained angiogenic ability with potentially significant clinical implications, such as response to anti-angiogenic treatments. (D) A patented device, the time-lapse analysis chamber for LCM, expands the capabilities of the commercially available Veritas LCM instrument by enabling time-lapse topography and image analysis of differentiating cell cultures and isolation of desired cell subpopulations for genomics and proteomics analyses. (E) Two other systems, the well-pressor and optic-pressor simulate the growth-induced mechanical stress in tumors and enable live cell imaging, cell tracking, and molecular analyses under normal loading. Data from these systems revealed that mechanical compression differentially regulates a specific set of genes that promote invasion and metastasis. In conclusion, these systems can be used independently or in tandem as discovery engines for the interplay and the individual roles of cellular and mechanochemical components in the progression of cancer.
BIOE Research Day
Friday, February 20, 2009, 12:00 - 1:00 pm, Room 210 Hallowell Building, CG624E Hershey
FINAL DEFENSE -“Shear Stress Elicits a Transient Domain-Dependent Alteration of the Plasma Membrane Fluidity in Endothelial Cells”
Tristan Tabouillot, Penn State
Thursday, February 26, 2009, 3:00pm - 4:00 pm, Room 210 Hallowell Building, CG624E Hershey
Abstract
Blood flow-associated shear stress causes physiological and pathophysiological biochemical processes in endothelial cells that may be initiated by alterations in plasma membrane domains. Time scales of cells signaling cascades triggered by shear stress spans seconds to hours. Hence, a single-molecule fluorescence spectroscopy system was developed to grasp cellular molecular dynamics with high spatial and temporal resolution. And, we defined a procedure to locate lipoid dyes in cultured endothelial cells under physiological conditions.
We assessed the photophysics and dynamics of the lipid analogues DiI-C12 and DiI-C18 in endothelial cells subjected to physiological fluid shear stress. These lipoid dyes are thought to segregate to domains of the membrane with thicknesses matching DiI alkyl chain length such that DiI-C12 partitions into the thinner liquid-disordered phase and DiI-C18 partitions into the thicker liquid-order phase. DiI fluorescence lifetime, molecular brightness, number of molecules, and lateral diffusion were obtained from time-correlated single photon counting data and analyzed as a function of shear stress and time. DiI-C12 fluorescence lifetime was less than DiI-C18 lifetime and the diffusion coefficient of DiI-C12 was greater than the DiI-C18 diffusion coefficient confirming that DiI-C12 probes more fluid membrane environment than DiI-C18. Domains probed by DiI-C12 dye exhibited an early decrease of fluorescence lifetime up to 20 seconds after the onset of shear while domains probed by DiI-C18 exhibited a delayed decrease of fluorescence lifetime that was sustained for the 2 minutes the cells were subjected to flow. Determination of the number of molecules in the control volume suggested that DiI-C12 -labeled domains increased in area while DiI-C18 -stained membrane did not. These results suggest that shear stress induces an early rippling of DiI-C12 –stained domains and later change in lipid mobility of DiI-C18 –stained domains. These results help focus attention on membrane microdomains, with their differential interaction with the glycocalyx and cytoskeleton, as sites of shear sensitivity.
FINAL DEFENSE- “Image Processing Tools for Quantitative Analysis of Magnetic Resonance Neuroimaging and Application To Amyotrophic Lateral Sclerosis”
Don Bigler, Penn State
Friday, March 6, 2009, 12:00 - 1:00 pm, Room 210 Hallowell Building, CG624E Hershey
Abstract
The diagnosis and evaluation of neurodegenerative disease using MRI is qualitative, subjective, and experience-based. Such conventional approaches are low in information to data ratio (IDR) and do not provide quantitative markers for disease evaluation. Currently the tools needed for quantitative MRI (qMRI) processing are not adequate for routine clinical usage. Thus, there is a need for image analysis tools for clinical applications and trials using qMRI. In this work tools were created to extend and enhance existing advanced registration tools for processing multi-modality MRI in parallel on a supercomputer. Also, an efficient method to automatically estimate thickness in a medical image is presented and validated using basic shapes and sample knee and brain MRI. Application of the method to a group comparison of mild cognitive impaired (MCI) subjects and normal control subjects using SPM5 demonstrated thinning in the hippocampus which is a well established finding. These tools were applied to a cross-sectional and longitudinal qMRI study of ALS. Regional thickness statistics performed using SPM5 were negative cross-sectionally and longitudinally. The right primary motor cortex (PMC) was significantly thinner for the ALS Limb only and ALS Probable groups. Longitudinally, the left PMC thickness correlated with time, disease duration, and severity. Thickness correlated significantly with cognitive exams in the left inferior temporal gyrus and right inferior occipital gyrus. Average 0.24%/month brain parenchyma fraction (BPF) decrease for duration for the General ALS group was significant (P = 0.0425). Ventricular fraction (VF) between baseline ALS and controls approached significance (P = 0.09827). Average 0.009%/month VF increase for duration and time was significant (P = 0.0576, P = 0.0528). Regional atrophy in gray matter (GM) and white matter (WM) correlated with duration and time in frontal, temporal, motor, parietal, and occipital brain regions. Using SPM5, clusters of significant T2 increase cross-sectionally were found in frontal and temporal areas and in the right corticospinal tract (CST) at the corona radiata (CR). The right CST at the CR was significant cross-sectionally in all three images. Longitudinally, increased T2 was associated with disease duration mainly in frontal areas, which overlapped with similar disease duration associated diffusion tensor imaging (DTI) mean diffusivity (MD) increases. In general the results of the ALS study were positive, but in all of the qMRI types studied changes due to disease were slight and the number of subjects was insufficient to determine whole brain group differences within ALS.
NO SEMINAR - Spring Break
Spring Break
Friday, March 13, 2009, 12:00 - 1:00 pm, Room 210 Hallowell Building, CG624E Hershey
FINAL DEFENSE - “Effects of Simultaneous Wall Shear Stress And Circumferential Strain on Endothelial Cell Junctions”
Danielle Berardi, Penn State
Friday, March 20, 2009, 12:00 - 1:00 pm, Room 210 Hallowell Building, CG624E Hershey
Abstract
Complex hemodynamics play a role in the localization and development of atherosclerosis. Endothelial cells (ECs) lining blood vessel walls are directly influenced by various hemodynamic forces: simultaneous wall shear stress (WSS), normal stress, and circumferential strain (CS) due to pulsatile flow, pressure, and diameter changes. As such, ECs may sense and transduce these forces into biomolecular responses at intracellular junctions. A hemodynamic simulator is used to investigate the combined effects of WSS and CS on EC junctions with emphasis on the stress phase angle (SPA), the temporal phase difference between WSS and CS. Regions of the circulation with highly negative SPA, such as the coronary arteries and carotid bifurcation, are more susceptible to the development of atherosclerosis.
At 5 hours, zonula occludens-1 relative protein expression was significantly lower for the atherogenic SPA = -180o compared to the normal SPA = 0o while mitosis (not statistically significant) and apoptosis (statistically significant) were both higher for SPA = -180o than SPA = 0o. This decrease in tight junction protein and increase in cell turnover, and “leaky junction” presence, may indicate a decreased junctional stability and a higher paraellular permeability for the atherogenic SPA = -180o than for SPA = 0o. Meanwhile, at 12 hours, protein expression levels and mitosis were not significantly different between SPA = -180o and SPA = 0o. Finally, changes in cell elongation and alignment were negligible at these time points.
Additionally, using a parallel plate flow chamber, the effects of short- and long-term exposure of ECs to WSS were examined for junctional markers as ECs remodel and align in the direction of flow over time. Indeed, ECs exposed to WSS for 24 hours significantly increased the alignment and elongation while significantly decreasing mitosis.
TBD
Friday, March 27, 2009, 3:30 - 4:30 pm, Room 210 Hallowell Building, CG624E Hershey
"The Use of Bone Marrow Stromal Cells for Engineering Scaffold-less Skeletal Tissue Constructs for Tissue Regeneration"
Lisa Larkin, University of Michigan
Friday, April 3, 2009, 12:00 - 1:00 pm, Room 210 Hallowell Building, CG624E Hershey
Abstract
End-stage organ failure or tissue loss is one of the most devastating and costly problems in medicine. Limitations associated tissue donation such as tissue availability, donor site morbidity, and immune rejection have led investigators to develop strategies to engineer tissue for replacement. The creation of engineered musculoskeletal tissues will not only restore the function of complex tissues such as muscle, tendon, ligament, bone and nerve following traumatic injury, but can also be used as a model for studying developmental muscle biology and muscle pharmacology. Current methodologies for engineering both musculoskeletal tissues utilize scaffolds that promote adhesion, migration and proliferation of cultured cells. While scaffolding strategies appear to promote cell growth, there are limitations such as immune rejection, degradation, and non-physiological mechanical properties of the scaffold need to be considered. To avoid these limitations, the Skeletal Tissue Engineering Laboratory (STEL) at the University of Michigan has developed a scaffold-less method to engineer three-dimensional (3D) muscle, tendon, bone and ligament constructs from both primary and bone marrow stromal cells (BMSCs). The purpose of STEL is to fabricate 3D musculoskeletal tissue and evaluate the structural and histological characteristics, to implant these tissues in vivo to expose them to the actual mechanical and biochemical environments of a hindlimb, to evaluate the alterations in the structural, functional and histological characteristics of these tissues in response to strain-shielded and unshielded mechanical environments, and to utilize the engineered constructs for tissue repair and replacement. This seminar will present highlights of research ongoing in STEL.
TBD
Friday, April 10, 2009, 12:00 - 1:00 pm, Room 210 Hallowell Building, CG624E Hershey
TBD
Friday, April 17, 2009, 12:00 - 1:00 pm, Room 210 Hallowell Building, CG624E Hershey
Student Presentations: Zhipeng Cao, Kimberly Griffith, Payal Khanna and David Porzio
Friday, April 24, 2009, 12:00 - 1:00 pm, Room 210 Hallowell Building, CG624E Hershey
“Towards an MRI Simulator with an Intuitive Interface for Evaluation of Field Effects on MR Images”
Zhipeng Cao, Advisor: Chris Collins
Abstract
Researchers in MRI development often face the challenge of high investment and instability for real systems. An MR simulator based on desktop computers with robust calculation ability is thus indentified as an important need of the MRI community. Here I report progress toward a simulator designed for ease of use in implementing and evaluating complex sequences and field distributions and facilitating accurate simulation of systems with multiple transmit and receive RF coils. An application is shown demonstrating the effects of a novel slice-selective array-optimized composite pulse by implementation in this simulator with 8 RF coils driven simultaneously with different waveforms.
“Evaluating Representation Guidelines for Cannula Performance”
Kimberly Griffith, Advisor: Bill Weiss
Abstract
The performance of the arterial cannula has the potential to greatly impact the overall outcome of the cardiopulmonary bypass procedure. For this reason, it is essential for the performance charts to be accurately represented. Current guidelines fail to emphasize previously made assumptions and the resultant degree of error. The fluid characteristics and clinical relevance of the performance data is explored in this study. Experimental data from three pediatric arterial cannulae were collected and evaluated.
Past and current research and clinical guidelines focus on the importance of a pressure limit threshold. The general standard may suffice for the adult population, but stricter guidelines must be investigated to minimize risk to the pediatric population in particular. The strict limitations of the pediatric field validate the need to identify further performance factors and validate performance representation.
“Characterization of the Tumor Microenvironment on Endothelial Signaling”
Payal Khanna, Advisor: Cheng Dong
Abstract
Endothelial vascular endothelial (VE)- cadherin junctions are involved in regulating endothelial barrier function, where breakdown of these junctions facilitates tumor extravasation and passage of immune cells (leukocytes, monocytes, etc.) through the post-capillary venule. Studies show the importance of the p38 mitogen activated protein kinase (MAPK) pathways in regulating endothelial permeability through inflammatory cytokines such as IL-1β. Using fluorescence microscopy, western blots, and ELISA, we show that cytokines from melanoma cells, interleukin (IL)-8, IL-6, IL-1β, and growth regulated oncogene (Gro)-α, breakdown VE-cadherin and activate the p38 MAP Kinase pathway in human umbilical vein endothelial cells (HUVECs). However, stimulation of human umbilical vein endothelial cells (HUVECs) with anti-VCAM-1 shows that adhesion events between VLA integrins on melanomas and VCAM-1 also play a significant role in breakdown of VE-cadherin and p38 MAP Kinase activation. Concentrations of pp38 over time in response to anti-VCAM-1 and cytokines were measured using western blots where densiometry was used to make quantitative measurements. The involvement of both cytokines and adhesion events in the breakdown of VE-cadherin suggest that other GTPases, MAPK proteins, and calcium signaling upstream of the p38 MAPK pathway all play an important role in these events. Current studies are focused on cell signaling network models within endothelial cells combined with statistical approaches to identify other important signaling proteins.
“Overview of Automated Lung Mesh Creation from Medical Images for Computational Fluid Dynamic Simulations of Respiration”
David Porzio, Advisor: Robert Kunz
Abstract
The creation of a high quality mesh from medical images for computational fluid dynamic simulations can be a very time intensive process; however, using physiologically real data in mesh creation can yield more meaningful results than those obtained by using a Weibel model or other schemes based upon averaged airway dimensions. Increases in medical imaging quality and computational power in the last decade have allowed for a finer resolved unstructured mesh to run in either comparable or fewer processor hours than its generic structured counterpart has in the past. This step forward has increased the physiologic significance of the mesh and subsequently also increased the need of a capability to quickly produce a mesh of desired regions from medical images. This talk will cover the automated process used to create a truncated mesh of the upper respiratory tract from a stereolithography file created from a series of transverse plane CT scans of a patient.
“Centrifugal Blood Pumps”
Gerald Miller, Virginia Commonwealth University
Monday, April 27, 2009, 1:30 - 2:30 pm, Room 210 Hallowell Building, CG628 Hershey
Abstract
The use of centrifugal blood pumps for cardiovascular support and heart assist have resulted from the marriage of a very successful class of standard fluid pumps with an urgent need to stem one of the largest causes of death in the United States – cardiovascular and heart pathologies. Centrifugal pumps have long been used as water pumps, oil pumps, air fans, and a host of other industrial, automotive, space, and home applications. They are one class of rotary pumps – the others being axial pumps and mixed-flow pumps. The use of such a pumping technology to address a growing need for cardiac support is a natural extension of these devices, and has resulted in the development of dozens of such pumps for use to propel blood. Over the last two decades, the use of rotary blood pumps, of which centrifugal pumps are one type, has steadily grown to the point that rotary pumps are now employed clinically as often as the more historically known positive displacement pumps, and lend themselves for use in both adult and pediatric cases.
Centrifugal pumps offer advantages over other pumping modalities in that they can produce large pressure increases and large flow rates at relatively low rotation speeds. As the history of centrifugal pumps for non-medical applications is long, the developments and advances in such a technology have been significant. Many centrifugal pumps have been used for specialized fluids including those which are highly volatile (such as rocket fuel) and those which have suspensions of particles (such as motor oil). Development of centrifugal pumps for such applications has resulted in versions that are designed for sensitive fluids and can thus produce stable flow regimes. The use of such pumps to propel blood is thus a natural extension, as this is another sensitive fluid which has deformable particles and which requires stable flow. It is thus not surprising that many centrifugal pumps are now employed for cardiovascular support and are in various stages of clinical and bench top trials.
Student Presentations: James Bauer, Hari Muddana, and Jason Mandell
Friday, May1, 2009, 2:00 - 3:00 pm, Room 210 Hallowell Building, CG624E Hershey
“Utilization of Thiol-Modified Surfaces to Investigate Contact Activation of Plasma Coagulation”
James Bauer, Advisor: Chris Sedleki
Abstract
Coagulation resulting from contact activation due to blood-material interactions remains a challenge in the use of blood-contacting cardiovascular materials. The current widespread view of contact activation imparts coagulation factor XII (FXII) activating abilities specific to anionic hydrophilic surfaces. However, previous studies from this group challenge this specificity to anionic-hydrophilic surfaces, and also suggest that surfaces with nanoscale chemical heterogeneity affect the plasma coagulation response. In this study one- and two-component thiol-modified surfaces were prepared and utilized as the procoagulant for in vitro coagulation assays.
Methods: Thiol-modified surfaces were prepared by immersing gold sputter-coated coverslips in 1mM ethanol solutions of dodecanethiol (C12), 11-mercaptoundecanoic acid (11-MUA), 11-mercapto-1-undecanol, 11-amino-1-undecanethiol, or mixtures of C12 with one of the other listed thiols. Sample surfaces were tested for clotting time in plasma coagulation assays and compared to baseline (null sample) clotting times. Results: Plasma coagulation assays of mixed thiol monolayers show trends warranting further investigation. Such behavior includes: 1) a sigmoidal transition region between contact angles of 50-70 degrees for 11-MUA:C12 mixtures; 2) an increased clotting time, near baseline, for 11-MUOH:C12 mixtures with contact angles near 50 degrees; and 3) clotting times above baseline for 11-amino-1-undecanethiol mixtures with 90 degree contact angles.
“Physiological Membrane Tension Causes an Increase in Lipid Diffusion: A Single Molecule Fluorescence Study”
Hari Muddana, Advisor: Peter Butler
Abstract
The quantitative relationship between lipid bilayer tension and lipid dynamics is currently unknown. We used time-correlated single photon counting (TCSPC) and fluorescence correlation spectroscopy (FCS) to determine diffusion of DiI, a lipoid dye, in micropipette-aspirated model membranes. Fluid-phase giant unilamellar vesicles (GUVs) were prepared from DOPC lipid using electroformation and stained with nanomolar concentrations of DiIC12. When GUVs were stressed from 0.02 to 0.1 mN/m, the diffusion coefficient increased monotonically from 9 x 10-8 to 13 x 10-8 cm2/sec. Thus, for the first time, we show that physiological tensions on the order of those experienced when cells are subjected to fluid shear stress or osmotic swelling induce substantial changes in lipid diffusion. These results suggest that tension directly causes changes in lipid diffusion, a phenomenon that may play a role in activation of integral membrane proteins. Conversely, this direct relationship may allow one to determine membrane stresses in cells from measured diffusion coefficients.
“Magnetic Resonance Imaging of Brain Morphology in Normal and Hydrocephalic Mice”
Jason Mandell, Advisor: Andrew Webb
Abstract
Obstructive hydrocephalus is created when the outflow of cerebrospinal fluid (CSF) is blocked. This occurs most often in infants and children and can be caused by a malformation, trauma, or infection in the brain. Experimental hydrocephalus can be created by injecting kaolin into the cisterna magna. Although animal models have been studied for years, brain and ventricular development of normal and hydrocephalic animals have not been well characterized. In this study, we quantify the development of brain and cerebrospinal fluid volumes in normal and kaolin-induced hydrocephalic mice using high-field MRI. The development was accurately determined for the C57 mouse from 2-12 weeks of age. The hydrocephalic ventricular volumes were clearly larger than the controls in all cases and the cortical thickness was often reduced; however the severity and time-course of the ventricular enlargement was highly variable for different mice
FINAL DEFENSE - “Functional Imaging of Intracellular Metabolic Cofactors in Human Normal and Cancer Breast Cells”
Qianru Yu, Penn State
Monday, June 15, 2009, 1:00 - 2:00 pm, Room 210 Hallowell Building, CG623 Hershey
Abstract
Reduced nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) are key metabolic cofactors in energy metabolism and redox reactions in live cells. Mitochondrial malfunction is related to numerous health problems such as cancer, neurodegenerative diseases, cardiomyopathy, and ageing. As a result, intracellular coenzymes have the potential to serve as natural biomarkers for the respiratory state activities and mitochondria-related health problems. Conventional biochemical methods have provided the bulk information on the concentration of these intrinsic cofactors using cell lysates and, therefore, a snapshot of the enzymatic activities in both normal and diseased cells. These biochemical techniques, however, are incapable of providing the morphological context and molecular conformation dynamics inherent in living cells or tissues. Other steady-state fluorescence-based techniques are limited by the ambiguous distinction between intrinsic NADH concentration and alteration of cellular autofluorescence, which is sensitive to the molecular conformation (i.e., free or enzyme-bound) as well as the complex cell environment. To overcome these limitations, we have developed integrated multimodal fluorescence microscopy and spectroscopy techniques, on a single platform, to differentiate between normal and cancer breast cells using intracellular NADH and FAD as natural biomarkers. Human breast cancer cell line (Hs578T) and its non-transformed fibroblast counterpart (Hs578Bst) from the same patient were used as model systems. To examine the sensitivity of our assay to different cell lines, a non-tumorigenic mammalian epithelial cell line (MCF10A) and the cancer cell line (MCF7) from different patients were also used. Complementary studies on primary and ras-transduced keratinocyte cells isolated from mice enabled us to assess the sensitivity of our experimental approach and these coenzymes to targeted alteration of key regulatory proteins. The environmental heterogeneity of intracellular cofactors was investigated using two-photon fluorescence lifetime imaging. These fluorescence lifetime and intensity images, recorded using a calibrated microscope, were analyzed to construct concentration images of the endogenous coenzymes at the single cell level. Time-resolved fluorescence anisotropy images were then used to obtain the fluorescence fraction of free and enzyme-bound NADH at the single-cell level. Complementary studies were also conducted using potassium cyanide to inhibit ETC enzymes in these model cells. Control experiments include NADH and FAD interactions with representative enzymes in solution. Using our integrated fluorescence assay, we also investigated the local environment and complexity of the inner membrane of mitochondria, with the mitochondrial tracker rhodamine 123. Our results are discussed in terms of the cell biology, cancer pathology, and related literature studies. The potential of our fluorescence-dynamics assay and future outlook are also outlined.
“Profilin-1 in Physiology and Pathology”
Partha Roy, University of Pittsburgh
Wednesday, June 24, 2009, 10:00 - 11:00 am, Room 210 Hallowell Building, CG623 Hershey
Abstract
Profilin-1 is the founding member of profilin family of genes and a ubiquitously expressed actin-binding protein that plays a key role in actin cytoskeletal regulation and embryonic development. Besides actin, profilin-1 also interacts with membrane phosphoinositides and a plethora of other ligands which are implicated in a multitude of cellular functions ranging from cytoskeletal regulation to gene transcription. Our studies have revealed an important role of profilin-1 in migration, invasion and capillary morphogenesis of vascular endothelial cells. Although profilin-1 has been traditionally conceived as a molecule required for cell migration and proliferation, interestingly its expression is significantly down-regulated in various adenocarcinoma including breast cancer. We will discuss molecular mechanisms underlying how profilin-1 dysregulation alters mammary tumor growth and aggressiveness.
Final Defense - “Electrical, Chemical, and Mechanical Manipulation of the Endothelial Cell Surface with a Multifunctional Nanopipette”
Chilman Bae, Penn State
Friday, July 3, 2009, 12:00 - 1:00 pm, Room 210 Hallowell Building, CG624F Hershey
Abstract
An integrated and automated micropipette electrode (ME)-based single-cell electroporation (SCE) system was developed for rapid, efficient, cell selective and non-invasive delivery of fluorescent compounds into adherent endothelial cells. Key features include software-controlled pulse waveform generation, continuous monitoring of electroporation events, feedback-controlled motorized micromanipulation, image capture, and data acquisition. The main innovations of automation are image-based cell selection, 40nm-precision feedback control of ME approach, and a method to prescribe the applied membrane potential. Comparisons of experiment measurements and finite element analysis of cleft resistance enabled identification of three distinct phases of pipette positioning: positioning phase, approach phase, and indenting phase. Computational simulations were also performed to determine the quantitative relationships of cleft size and resistance, transmembrane potential (TP) and cleft size, and TP and electrode axial distance. The simulation also shows that pores are focused on the membrane area corresponding to the inner pipette lumen. In addition, we quantitatively determined membrane tension, stress, and strain distributions in the vicinity of a nanoelectrode using finite element analysis of a multiscale electro-mechanical model which consisted of pipette, media, membrane, actin cortex, and cytoplasm. Results suggest that nanopipette electrodes (nE) provide a new non-contact method to deliver physiological stresses directly to membranes in a focused and controlled manner, thus providing the quantitative foundation for microelectrotension. Finally, we developed a new simple method for dynamic deformation spectroscopy with a functionalized nE. The electrical and mechanical characteristics of the system and the system resolution were tested. The results suggest that the adhesion of a nanopipette electrode tip onto the cell surface is dependent on the nanopipette electrode tip size, the fibronectin concentration for coating the nanopipette electrode tip, and the reaction time. This system has high versatility because of its simplicity, easy of interpretation, and non-contact analysis of surface properties.
Final Defense - “Ultrasonic Transdermal Glucose Monitoring and Insulin Delivery Using Cymbal Transducer Arrays”
Eun-Joo Park, Penn State
Wednesday, July 29, 2009, 9:00 - 10:00 am, Room 210 Hallowell Building, CG628 Hershey
Abstract
As a practically portable ultrasound system in transdermal insulin delivery and glucose sensing, the cymbal transducer array has shown promise in several in vivo experiments using small animals. The goal of this study is to evaluate the potential of the cymbal transducer array as a pre-clinical application for transdermal insulin delivery and glucose sensing. In order to achieve this goal, several aspects have been investigated, such as the comparison of insulin dose of ultrasonic delivery to the direct injection, the efficacy of the modified cymbal transducer array, the feasibility of ultrasonic transdermal insulin delivery and glucose sensing in large animals and feasibility of combined ultrasound system for the glucose control by using a feedback controller. Several in vivo experiments were designed to perfume these tasks. Through the in vivo experiments which were designed to perfume these tasks, the ultrasound system using the cymbal transducer array has shown the positive potential of a practically portable device for a clinical application of diabetes care.
For additional information, contact Ms. Doretta Garvey, Dept of Bioengineering, Tel: 814.865.1407 or E-Mail: bioe@engr.psu.edu