Scanning Electrochemical Microscopy of Human Bladder Cancer (T24) Cells

Scanning electrochemical microscopy (SECM) employs a biased ultramicroelectrode (few nm to 25 µm diameter) as a probe that is scanned over a sample to electrochemically characterize its physical properties and chemical reactivity with high temporal and spatial resolutions. In this dissertation, SECM was used to investigate the membrane responses of single live human bladder cancer (T24) cells to obtain insights into their topography, physiology and pathology. First, the membrane-impermeable ferrocene carboxylate was used as the SECM redox mediator to investigate the geometry and topography of these cells along with 3D finite elemental analysis (FEA) simulations. The use of 3D simulation models now allows characterization of asymmetric samples, previously restricted to a 2D axially symmetric geometry. Upon exposure to toxic and non-essential Cd2+ (mM range), the membrane permeability to the hydrophobic mediator, ferrocenemethanol, in T24 cells increased within minutes. Time-lapsed SECM was able to measure and quantify these changes in membrane permeability. Expanding on this work, T24 cells were exposed to low exposure (25 µM, up to 6 hours) or 1 hour of acute Cd2+ concentrations. Specifically, the permeation of hydrophilic redox mediators: ferrocene carboxylate, ferrocene dicarboxylate, and hexaamineruthenium(III), into the Cd2+-treated T24 cells confirmed membrane integrity loss. In conjunction with FEA, the membrane permeability coefficients were quantified. A correlation between cellular loss and membrane integrity was confirmed using MTT cell proliferation assays. Exposure to the trace essential Zn2+ (0-75 µM, 24 hours) did not significantly affect the cell membranes of T24 cells. Higher Zn2+-treatment led to cytotoxicity, where membrane integrity loss (increased permeation) and cellular death were observed (100-400 µM). The above discoveries suggested the Zn2+-induced apoptosis in these cells. This was confirmed by several apoptotic indicators, such as the externalization of phosphatidylserine and activation of caspases 3 and 7. Finally, to improve the spatial resolution of SECM, a fabrication method of nanometer-sized probes was successfully developed. This led to the reduction of Pt electrode disk diameters from 25 µm to 25 nm. Visualization of reactivity features of nanometer-sized samples using SECM is anticipated with this advancement

Optimizing the Pedagogical Efficacy of Moodle

Course Management Systems (CMS) such as Moodle, D2L, and Blackboard are often used as auxiliary resources for both traditional and online courses. As CSB/SJU faculty, many of us are developing and using creative CMS resources with the goal of positive pedagogical impact. How is the effectiveness of these resources assessed? Which resources are found most useful by students? How can faculty maximize the pedagogical value of CMS? This Thursday Forum presentation shows participants the results of a study directed toward answering these questions. During three introductory financial accounting courses conducted in 2009, 2010, and 2011, Camtasia videos, assignment solutions, notes, slides, WebEx recordings, homework discussion forums, and other Moodle resources were available to students. Analyses were performed to determine whether student Moodle use correlated with student performance. A pre- and post-course exam was administered to assess student learning as related to Moodle use. In addition, a student survey was conducted to gather evidence about which resources were deemed most useful by students and to compare student perceptions of usefulness with actual use. The forum presentation also shows how to track student use of Moodle resources via the direct and indirect assessment methods used in the study. Examples of student preferred resources are also shown

Graph Representation Learning in Biomedicine

Biomedical networks are universal descriptors of systems of interacting elements, from protein interactions to disease networks, all the way to healthcare systems and scientific knowledge. With the remarkable success of representation learning in providing powerful predictions and insights, we have witnessed a rapid expansion of representation learning techniques into modeling, analyzing, and learning with such networks. In this review, we put forward an observation that long-standing principles of networks in biology and medicine -- while often unspoken in machine learning research -- can provide the conceptual grounding for representation learning, explain its current successes and limitations, and inform future advances. We synthesize a spectrum of algorithmic approaches that, at their core, leverage graph topology to embed networks into compact vector spaces, and capture the breadth of ways in which representation learning is proving useful. Areas of profound impact include identifying variants underlying complex traits, disentangling behaviors of single cells and their effects on health, assisting in diagnosis and treatment of patients, and developing safe and effective medicines

Fibulin-4 is essential for maintaining arterial wall integrity in conduit but not muscular arteries

Homozygous or compound heterozygous mutations in fibulin-4 (FBLN4) lead to autosomal recessive cutis laxa type 1B (ARCL1B), a multisystem disorder characterized by significant cardiovascular abnormalities, including abnormal elastin assembly, arterial tortuosity, and aortic aneurysms. We sought to determine the consequences of a human disease-causing mutation in FBLN4 (E57K) on the cardiovascular system and vascular elastic fibers in a mouse model of ARCL1B. Fbln4E57K/E57K mice were hypertensive and developed arterial elongation, tortuosity, and ascending aortic aneurysms. Smooth muscle cell organization within the arterial wall of large conducting vessels was abnormal, and elastic fibers were fragmented and had a moth-eaten appearance. In contrast, vessel wall structure and elastic fiber integrity were normal in resistance/muscular arteries (renal, mesenteric, and saphenous). Elastin cross-linking and total elastin content were unchanged in large or small arteries, whereas elastic fiber architecture was abnormal in large vessels. While the E57K mutation did not affect Fbln4 mRNA levels, FBLN4 protein was lower in the ascending aorta of mutant animals compared to wild-type arteries but equivalent in mesenteric arteries. We found a differential role of FBLN4 in elastic fiber assembly, where it functions mainly in large conduit arteries. These results suggest that elastin assembly has different requirements depending on vessel type. Normal levels of elastin cross-links in mutant tissue call into question FBLN4\u27s suggested role in mediating lysyl oxidase-elastin interactions. Future studies investigating tissuespecific elastic fiber assembly may lead to novel therapeutic interventions for ARCL1B and other disorders of elastic fiber assembly. 2017 © The Authors, some rights reserved

Leveraging Commercial Cloud Navigation and Maps for Special Event Route Management

Universities and sports venues routinely host large events that often attract over 100,000 attendants. These special events create and encounter unique challenges, such as motorists unfamiliar with the area, streets that must be closed for security and crowd management, non-traditional parking, and strong demand immediately after the event. Traditionally, special parking and routing plans have been communicated by static maps and, more recently, static maps posted on web sites. This presentation discusses the implementation of cloud-based maps (maps.google.com) that provide recommended turn by turn directions to and from 26 parking lots associated with the Purdue Football home game activities. These maps were developed in close coordination with public safety and athletics staff. The resultant maps were communicated to season pass holders and other visitors using QR codes printed on parking passes as well as a variety of electronic media. In addition to covering the map generation process, this presentation will share some of the lessons learned and ongoing activities related to special event management

Dosimetric Performance and Planning/Delivery Efficiency of a Dual-Layer Stacked and Staggered MLC on Treating Multiple Small Targets: A Planning Study Based on Single-Isocenter Multi-Target Stereotactic Radiosurgery (SRS) to Brain Metastases.

Purpose: To evaluate the dosimetric performance and planning/delivery efficiency of a dual-layer MLC system for treating multiple brain metastases with a single isocenter. Materials and Methods: 10 patients each with 6-10 targets with volumes from 0.11 to 8.57 cc, and prescription doses from 15 to 24 Gy, were retrospectively studied. Halcyon has only coplanar delivery mode. Halcyon V1 MLC modulates only with the lower layer at 1 cm resolution, whereas V2 MLC modulates with both layers at an effective resolution of 0.5 cm. For each patient five plans were compared varying MLC and beam arrangements: the clinical plan using multi-aperture dynamic conformal arc (DCA) and non-coplanar arcs, Halcyon-V1 using coplanar-VMAT, Halcyon-V2 using coplanar-VMAT, HDMLC-0.25 cm using coplanar-VMAT, and HDMLC-0.25 cm using non-coplanar-VMAT. All same-case plans were generated following the same planning protocol and normalization. Conformity index (CI), gradient index (GI), V12Gy, V6Gy, V3Gy, and brain mean dose were compared. Results: All VMAT plans met clinical constraints for critical structures. For targets with diameter \u3c 1 cm, Halcyon plans showed inferior CI among all techniques. For targets with diameter \u3e1 cm, Halcyon VMAT plans had CI similar to non-coplanar VMAT plans, and better than non-coplanar clinical DCA plans. For GI, Halcyon MLC plans performed similarly to coplanar HDMLC plans and inferiorly compared to non-coplanar HDMLC plans. All coplanar VMAT plans (Halcyon MLC and HDMLC) and clinical DCA plans had similar V12Gy, but were inferior compared to non-coplanar VMAT plans. Halcyon plans had slightly reduced V3Gy and mean brain dose compared to HDMLC plans. The difference between Halcyon V1 and V2 is only significant in CI of tumors less than 1cm in diameter. Halcyon plans required longer optimization than Truebeam VMAT plans, but had similar delivery efficiency. Conclusion: For targets with diameter \u3e1 cm, Halcyon\u27s dual-layer stacked and staggered MLC is capable of producing similar dose conformity compared to HDMLC while reducing low dose spill to normal brain tissue. GI and V12Gy of Halcyon MLC plans were, in general, inferior to non-coplanar DCA or VMAT plans using HDMLC, likely due to coplanar geometry and wider MLC leaves. HDMLC maintained its advantage in CI for smaller targets with diameter \u3c1 cm. © 2019 Li, Irmen, Liu, Shi, Alonso-Basanta, Zou, Teo, Metz and Dong

Do ultrafast exciton-polaron decoherence dynamics govern photocarrier generation efficiencies in polymer solar cells?

All-organic-based photovoltaic solar cells have attracted considerable attention because of their low-cost processing and short energy payback time. In such systems the primary dissociation of an optical excitation into a pair of photocarriers has been recently shown to be extremely rapid and efficient, but the physical reason for this remains unclear. Here, two-dimensional photocurrent excitation spectroscopy, a novel non-linear optical spectroscopy, is used to probe the ultrafast coherent decay of photoexcitations into charge-producing states in a polymer:fullerene based solar cell. The two-dimensional photocurrent spectra are interpreted by introducing a theoretical model for the description of the coupling of the electronic states of the system to an external environment and to the applied laser fields. The experimental data show no cross-peaks in the two-dimensional photocurrent spectra, as predicted by the model for coherence times between the exciton and the photocurrent producing states of 20\,fs or less