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896 results on '"Skala, Melissa C"'

202. Oxidative stress via inhibition of the mitochondrial electron transport and Nrf-2-mediated anti-oxidative response regulate the cytotoxic activity of plumbagin

Author

Kapur, Arvinder, primary, Beres, Thomas, additional, Rathi, Kavya, additional, Nayak, Amruta P., additional, Czarnecki, Austin, additional, Felder, Mildred, additional, Gillette, Amani, additional, Ericksen, Spencer S., additional, Sampene, Emmanuel, additional, Skala, Melissa C., additional, Barroilhet, Lisa, additional, and Patankar, Manish S., additional

Published
2018
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204. Reproducibility and staging of 3D human retinal organoids across multiple pluripotent stem cell lines

Author

Capowski, Elizabeth E., primary, Samimi, Kayvan, additional, Mayerl, Steven J., additional, Phillips, M. Joseph, additional, Pinilla, Isabel, additional, Howden, Sara E., additional, Saha, Jishnu, additional, Jansen, Alex D., additional, Edwards, Kimberly L., additional, Jager, Lindsey D., additional, Barlow, Katherine, additional, Valiauga, Rasa, additional, Erlichman, Zachary, additional, Hagstrom, Anna, additional, Sinha, Divya, additional, Sluch, Valentin M., additional, Chamling, Xitiz, additional, Zack, Donald J., additional, Skala, Melissa C., additional, and Gamm, David M., additional

Published
2018
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205. Signal and response properties indicate an optoacoustic effect underlying the intra-cochlear laser-optical stimulation

Author

Kallweit, Nicole, Baumhoff, Peter, Krueger, Alexander, Tinne, Nadine, Heisterkamp, Alexander, Kral, Andrej, Maier, Hannes, Ripken, Tammo, Choi, Bernard, Kollian, Nikiforos, Zeng, Haishan, Kang, Hyun Wook, Wong, Brian J.F., Ilgner, Justus F., Tearney, Guillermo J., Gregory, Kenton W., Marcu, Laura, Skala, Melissa C., Campagnola, Paul J., and Mandelis, Andreas

Subjects
Materials science, Dewey Decimal Classification::600 | Technik::620 | Ingenieurwissenschaften und Maschinenbau, Stimulation, 01 natural sciences, Absorption, law.invention, 010309 optics, 03 medical and health sciences, 0302 clinical medicine, Optics, law, 0103 physical sciences, otorhinolaryngologic diseases, medicine, Infrared radiation, Konferenzschrift, Cochlea, Spiral ganglion, Photoacoustic effect, Sensors, business.industry, Pulse duration, Pulsed laser operation, Laser, medicine.anatomical_structure, Amplitude, Attenuation coefficient, In vivo imaging, Laser systems engineering, sense organs, ddc:620, business, 030217 neurology & neurosurgery, Signal detection
Abstract

Optical cochlea stimulation is under investigation as a potential alternative to conventional electric cochlea implants in treatment of sensorineural hearing loss. If direct optical stimulation of spiral ganglion neurons (SGNs) would be feasible, a smaller stimulation volume and, therefore, an improved frequency resolution could be achieved. However, it is unclear whether the mechanism of optical stimulation is based on direct neuronal stimulation or on optoacoustics. Animal studies on hearing vs. deafened guinea pigs already identified the optoacoustic effect as potential mechanism for intra-cochlear optical stimulation. In order to characterize the optoacoustic stimulus more thoroughly the acoustic signal along the beam path of a pulsed laser in water was quantified and compared to the neuronal response properties of hearing guinea pigs stimulated with the same laser parameters. Two pulsed laser systems were used for analyzing the influence of variable pulse duration, pulse energy, pulse peak power and absorption coefficient. Preliminary results of the experiments in water and in vivo suggesta similar dependency of response signals on the applied laser parameters: Both datasets show an onset and offset signal at the beginning and the end of the laser pulse. Further, the resulting signal amplitude depends on the pulse peak power as well as the temporal development of the applied laser pulse. The data indicates the maximum of the first derivative of power as the decisive factor. In conclusion our findings strengthen the hypothesis of optoacoustics as the underlying mechanism for optical stimulation of the cochlea. © SPIE 2016

Published
2016
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206. Three-dimensional imaging of intracochlear tissue by scanning laser optical tomography (SLOT)

Author

Tinne, N., Nolte, L., Antonopoulos, Georgios C., Schulze, J., Andrade, J., Heisterkamp, A., Meyer, H., Warnecke, A., Majdani, Omid, Ripken, T., Choi, Bernard, Kollian, Nikiforos, Zeng, Haishan, Kang, Hyun Wook, Wong, Brian J.F., Ilgner, Justus F., Tearney, Guillermo J., Gregory, Kenton W., Marcu, Laura, Skala, Melissa C., Campagnola, Paul J., and Mandelis, Andreas

Subjects
inner ear, Materials science, cochlea, Dewey Decimal Classification::600 | Technik::620 | Ingenieurwissenschaften und Maschinenbau, tomography, 3-D microscopy, 01 natural sciences, Antibodies, Fluorescence, law.invention, 010309 optics, 03 medical and health sciences, antibody staining, Optical clearing, 0302 clinical medicine, Optics, Optical microscope, law, 0103 physical sciences, Microscopy, medicine, Scanning, Scanning lasers, Optical tomography, Konferenzschrift, Cochlea, Visualization, Tissue, Tomographic reconstruction, ?CT, medicine.diagnostic_test, business.industry, Computerized tomography, Laser, scanning laser optical tomography, Autofluorescence, 3D microscopy, sense organs, Tomography, ddc:620, business, 030217 neurology & neurosurgery, SLOT
Abstract

The presented study focuses on the application of scanning laser optical tomography (SLOT) for non-destructive visualization of anatomical structures inside the human cochlea ex vivo. SLOT is a laser-based highly efficient microscopy technique, which allows for tomographic imaging of the internal structure of transparent large-scale specimens (up to 1 cm3). Thus, in the field of otology this technique is best convenient for an ex vivo study of the inner ear anatomy. For this purpose, the preparation before imaging comprises mechanically assisted decalcification, dehydration as well as optical clearing of the cochlea samples. Here, we demonstrate results of SLOT visualizing hard and soft tissue structures of the human cochlea with an optical resolution in the micrometer range using absorption and autofluorescence as contrast mechanisms. Furthermore, we compare our results with the method of X-ray micro tomography (micro-CT, μCT) as clinical gold standard which is based only on absorption. In general, SLOT can provide the advantage of covering all contrast mechanisms known from other light microscopy techniques, such as fluorescence or scattering. For this reason, a protocol for antibody staining has been developed, which additionally enables selective mapping of cellular structures within the cochlea. Thus, we present results of SLOT imaging rodent cochleae showing specific anatomical structures such as hair cells and neurofilament via fluorescence. In conclusion, the presented study has shown that SLOT is an ideally suited tool in the field of otology for in toto visualization of the inner ear microstructure. © 2016 SPIE.

Published
2016
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207. Influence of distance and incident angle on light intensities in intravascular optical coherence tomography pullback runs

Author

Liu, Shengnan, Eggermont, Jeroen, Wolterbeek, Ron, Lelieveldt, B.P.F., Dijkstra, J, Wook Kang, Hyun, Tearney, Guillermo J., Gregory, Kenton W., Marcu, Laura, Skala, Melissa C., Campagnola, Paul J., Choi, Bernard, Kollias, Nikiforos, Zeng, Haishan, Mandelis, Andreas, Wong, Brian J.F., and Ilgner, Justus F.

Subjects
030204 cardiovascular system & hematology, 01 natural sciences, 010309 optics, compensation, 03 medical and health sciences, IVOCT, 0302 clinical medicine, Optics, Optical coherence tomography, statistical analysis, 0103 physical sciences, medicine, Statistical analysis, catheter position, distance, angle of incidence, Physics, medicine.diagnostic_test, business.industry, Potential effect, Ray, intravascular optical coherence tomography, hierarchical linear regression, Homogeneous, business, Intravascular imaging, Lumen (unit)
Abstract

Intravascular optical coherence tomography (IVOCT) is an intravascular imaging modality which enables the visualization arterial structures at the micro-structural level. The interpretations of these structures is mainly on the basis of relative image intensities. However, even for homogeneous tissue light intensities can differ. In this study the incident light intensity is modeled to be related to the catheter position. Two factors, the distance between catheter and inner lumen wall as well as the incident angle of the light upon the lumen wall, are considered. A three-level hierarchical model is constructed to statistically validate this model to include the potential effect of different pullbacks and/or frame numbers. The model is solved using 169 images out of 9 pull-backs recorded with a St.Jude Medical IVOCT system. F-tests results indicate that both the distance and the incident angle contribute to the model statistically significantly with p < 0.001. Based on the results from the statistical analysis, a potential compensation method is introduced to normalize the IVOCT intensities for the catheter position effects and small shadows.

Published
2016

221. Dysfunctional BMPR2 signaling drives an abnormal endothelial requirement for glutamine in pulmonary arterial hypertension

Author

Egnatchik, Robert A., primary, Brittain, Evan L., additional, Shah, Amy T., additional, Fares, Wassim H., additional, Ford, H. James, additional, Monahan, Ken, additional, Kang, Christie J., additional, Kocurek, Emily G., additional, Zhu, Shijun, additional, Luong, Thong, additional, Nguyen, Thuy T., additional, Hysinger, Erik, additional, Austin, Eric D., additional, Skala, Melissa C., additional, Young, Jamey D., additional, Roberts, L. Jackson, additional, Hemnes, Anna R., additional, West, James, additional, and Fessel, Joshua P., additional

Published
2017
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227. Redox imaging and optical coherence tomography of the respiratory ciliated epithelium.

Author

Gil, Daniel A., Sharick, Joe T., Mancha, Sophie, Gamm, Ute A., Choma, Michael A., and Skala, Melissa C.

Subjects
FLAVIN adenine dinucleotide, OPTICAL images, PARTICLE tracking velocimetry, OPTICAL coherence tomography, OXIDATION-reduction reaction, OBSTRUCTIVE lung diseases, OPTICAL tomography
Abstract

Optical coherence tomography (OCT) is an emerging technology for in vivo airway and lung imaging. However, OCT lacks sensitivity to the metabolic changes caused by inflammation, which drives chronic respiratory diseases such as asthma and chronic obstructive pulmonary disorder. Redox imaging (RI) is a label-free technique that uses the autofluorescence of the metabolic coenzymes NAD(P)H and flavin adenine dinucleotide (FAD) to probe cellular metabolism and could provide complimentary information to OCT for airway and lung imaging. We demonstrate OCT and RI of respiratory ciliated epithelial function in ex vivo mouse tracheae. We applied RI to measure cellular metabolism via the redox ratio [intensity of NAD(P)H divided by FAD] and particle tracking velocimetry OCT to quantify cilia-driven fluid flow. To model mitochondrial dysfunction, a key aspect of the inflammatory process, cyanide was used to inhibit oxidative metabolism and reduce ciliary motility. Cyanide exposure over 20 min significantly increased the redox ratio and reversed cilia-driven fluid flow. We propose that RI provides complementary information to OCT to assess inflammation in the airway and lungs. [ABSTRACT FROM AUTHOR]

Published
2019
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228. Drug-Free ROS Sponge Polymeric Microspheres Reduce Tissue Damage from Ischemic and Mechanical Injury

Author

O’Grady, Kristin P., Kavanaugh, Taylor E., Cho, Hongsik, Ye, Hanrong, Gupta, Mukesh K., Madonna, Megan C., Lee, Jinjoo, O’Brien, Christine M., Skala, Melissa C., Hasty, Karen A., and Duvall, Craig L.

Abstract

The inherent antioxidant function of poly(propylene sulfide) (PPS) microspheres (MS) was dissected for different reactive oxygen species (ROS), and therapeutic benefits of PPS-MS were explored in models of diabetic peripheral arterial disease (PAD) and mechanically induced post-traumatic osteoarthritis (PTOA). PPS-MS (∼1 μm diameter) significantly scavenged hydrogen peroxide (H2O2), hypochlorite, and peroxynitrite but not superoxide in vitro in cell-free and cell-based assays. Elevated ROS levels (specifically H2O2) were confirmed in both a mouse model of diabetic PAD and in a mouse model of PTOA, with greater than 5- and 2-fold increases in H2O2, respectively. PPS-MS treatment functionally improved recovery from hind limb ischemia based on ∼15–25% increases in hemoglobin saturation and perfusion in the footpads as well as earlier remodeling of vessels in the proximal limb. In the PTOA model, PPS-MS reduced matrix metalloproteinase (MMP) activity by 30% and mitigated the resultant articular cartilage damage. These results suggest that local delivery of PPS-MS at sites of injury-induced inflammation improves the vascular response to ischemic injury in the setting of chronic hyperglycemia and reduces articular cartilage destruction following joint trauma. These results motivate further exploration of PPS as a stand-alone, locally sustained antioxidant therapy and as a material for microsphere-based, sustained local drug delivery to inflamed tissues at risk of ROS damage.

Published
2024
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229. Signal and response properties indicate an optoacoustic effect underlying the intra-cochlear laser-optical stimulation

Author

Choi, Bernard, Kollian, Nikiforos, Zeng, Haishan, Kang, Hyun Wook, Wong, Brian J.F., Ilgner, Justus F., Tearney, Guillermo J., Gregory, Kenton W., Marcu, Laura, Skala, Melissa C., Campagnola, Paul J., Mandelis, Andreas, Kallweit, Nicole, Baumhoff, Peter, Krueger, Alexander, Tinne, Nadine, Heisterkamp, Alexander, Kral, Andrej, Maier, Hannes, Ripken, Tammo, Choi, Bernard, Kollian, Nikiforos, Zeng, Haishan, Kang, Hyun Wook, Wong, Brian J.F., Ilgner, Justus F., Tearney, Guillermo J., Gregory, Kenton W., Marcu, Laura, Skala, Melissa C., Campagnola, Paul J., Mandelis, Andreas, Kallweit, Nicole, Baumhoff, Peter, Krueger, Alexander, Tinne, Nadine, Heisterkamp, Alexander, Kral, Andrej, Maier, Hannes, and Ripken, Tammo

Abstract

Optical cochlea stimulation is under investigation as a potential alternative to conventional electric cochlea implants in treatment of sensorineural hearing loss. If direct optical stimulation of spiral ganglion neurons (SGNs) would be feasible, a smaller stimulation volume and, therefore, an improved frequency resolution could be achieved. However, it is unclear whether the mechanism of optical stimulation is based on direct neuronal stimulation or on optoacoustics. Animal studies on hearing vs. deafened guinea pigs already identified the optoacoustic effect as potential mechanism for intra-cochlear optical stimulation. In order to characterize the optoacoustic stimulus more thoroughly the acoustic signal along the beam path of a pulsed laser in water was quantified and compared to the neuronal response properties of hearing guinea pigs stimulated with the same laser parameters. Two pulsed laser systems were used for analyzing the influence of variable pulse duration, pulse energy, pulse peak power and absorption coefficient. Preliminary results of the experiments in water and in vivo suggesta similar dependency of response signals on the applied laser parameters: Both datasets show an onset and offset signal at the beginning and the end of the laser pulse. Further, the resulting signal amplitude depends on the pulse peak power as well as the temporal development of the applied laser pulse. The data indicates the maximum of the first derivative of power as the decisive factor. In conclusion our findings strengthen the hypothesis of optoacoustics as the underlying mechanism for optical stimulation of the cochlea. © SPIE 2016

Published
2016

244. Imaging Cellular Metabolic Heterogeneity in Cancer

Author

Skala, Melissa C., primary, Walsh, Alex J., additional, Shah, Amy T., additional, Sharick, Joseph T., additional, Heaster, Tiffany M., additional, Cook, Rebecca S., additional, Arteaga, Carlos L., additional, Sanders, Melinda E., additional, and Meszoely, Ingrid, additional

Published
2016
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247. Autofluorescence imaging identifies tumor cell‐cycle status on a single‐cell level.

Author

Heaster, Tiffany M., Walsh, Alex J., Zhao, Yue, Hiebert, Scott W., and Skala, Melissa C.

Abstract

Abstract: The goal of this study is to validate fluorescence intensity and lifetime imaging of metabolic co‐enzymes NAD(P)H and FAD (optical metabolic imaging, or OMI) as a method to quantify cell‐cycle status of tumor cells. Heterogeneity in tumor cell‐cycle status (e. g. proliferation, quiescence, apoptosis) increases drug resistance and tumor recurrence. Cell‐cycle status is closely linked to cellular metabolism. Thus, this study applies cell‐level metabolic imaging to distinguish proliferating, quiescent, and apoptotic populations. Two‐photon microscopy and time‐correlated single photon counting are used to measure optical redox ratio (NAD(P)H fluorescence intensity divided by FAD intensity), NAD(P)H and FAD fluorescence lifetime parameters. Redox ratio, NAD(P)H and FAD lifetime parameters alone exhibit significant differences (p<0.05) between population means. To improve separation between populations, linear combination models derived from partial least squares ‐ discriminant analysis (PLS‐DA) are used to exploit all measurements together. Leave‐one‐out cross validation of the model yielded high classification accuracies (92.4 and 90.1 % for two and three populations, respectively). OMI and PLS‐DA also identifies each sub‐population within heterogeneous samples. These results establish single‐cell analysis with OMI and PLS‐DA as a label‐free method to distinguish cell‐cycle status within intact samples. This approach could be used to incorporate cell‐level tumor heterogeneity in cancer drug development. [ABSTRACT FROM AUTHOR]

Published
2018
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