31 results on '"Epel, Boris"'
Search Results
2. Nondestructive, longitudinal, 3D oxygen imaging of cells in a multi-well plate using pulse electron paramagnetic resonance imaging
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Hameed, Safa, Viswakarma, Navin, Babakhanova, Greta, Simon, Jr., Carl G., Epel, Boris, and Kotecha, Mrignayani
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- 2024
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3. 4D-image reconstruction directly from limited-angular-range data in continuous-wave electron paramagnetic resonance imaging
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Zhang, Zheng, Epel, Boris, Chen, Buxin, Xia, Dan, Sidky, Emil Y., Qiao, Zhiwei, Halpern, Howard, and Pan, Xiaochuan
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Physics - Medical Physics - Abstract
Objective: We investigate and develop optimization-based algorithms for accurate reconstruction of four-dimensional (4D)-spectral-spatial (SS) images directly from data collected over limited angular ranges (LARs) in continuous-wave (CW) electron paramagnetic resonance imaging (EPRI). Methods: Basing on a discrete-to-discrete data model devised in CW EPRI employing the Zeeman-modulation (ZM) scheme for data acquisition, we first formulate the image reconstruction problem as a convex, constrained optimization program that includes a data fidelity term and also constraints on the individual directional total variations (DTVs) of the 4D-SS image. Subsequently, we develop a primal-dual-based DTV algorithm, simply referred to as the DTV algorithm, to solve the constrained optimization program for achieving image reconstruction from data collected in LAR scans in CW-ZM EPRI. Results: We evaluate the DTV algorithm in simulated- and real-data studies for a variety of LAR scans of interest in CW-ZM EPRI, and visual and quantitative results of the studies reveal that 4D-SS images can be reconstructed directly from LAR data, which are visually and quantitatively comparable to those obtained from data acquired in the standard, full-angular-range (FAR) scan in CW-ZM EPRI. Conclusion: An optimization-based DTV algorithm is developed for accurately reconstructing 4D-SS images directly from LAR data in CW-ZM EPRI. Future work includes the development and application of the optimization-based DTV algorithm for reconstructions of 4D-SS images from FAR and LAR data acquired in CW EPRI employing schemes other than the ZM scheme. Significance: The DTV algorithm developed may be exploited potentially for enabling and optimizing CW EPRI with minimized imaging time and artifacts by acquiring data in LAR scans., Comment: Submitted to Journal of Magnetic Resonance
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- 2023
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4. In vitro oxygen imaging of acellular and cell-loaded beta cell replacement devices
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Kotecha, Mrignayani, Wang, Longhai, Hameed, Safa, Viswakarma, Navin, Ma, Minglin, Stabler, Cherie, Hoesli, Corinne A., and Epel, Boris
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- 2023
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5. Development of a PET/EPRI combined imaging system for assessing tumor hypoxia
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Kim, Heejong, Epel, Boris, Sundramoorthy, Subramanian, Tsai, Hsiu-Ming, Barth, Eugene, Gertsenshteyn, Inna, Halpern, Howard, Hua, Yuexuan, Xie, Qingguo, Chen, Chin-Tu, and Kao, Chien-Min
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Physics - Medical Physics ,Physics - Instrumentation and Detectors - Abstract
Precise quantitative delineation of tumor hypoxia is essential in radiation therapy treatment planning to improve the treatment efficacy by targeting hypoxic sub-volumes. We developed a combined imaging system of positron emission tomography (PET) and electron para-magnetic resonance imaging (EPRI) of molecular oxygen to investigate the accuracy of PET imaging in assessing tumor hypoxia. The PET/EPRI combined imaging system aims to use EPRI to precisely measure the oxygen partial pressure in tissues. This will evaluate the validity of PET hypoxic tumor imaging by (near) simultaneously acquired EPRI as ground truth. The combined imaging system was constructed by integrating a small animal PET scanner (inner ring diameter 62 mm and axial field of view 25.6 mm) and an EPRI subsystem (field strength 25 mT and resonant frequency 700 MHz). The compatibility between the PET and EPRI subsystems were tested with both phantom and animal imaging. Hypoxic imaging on a tumor mouse model using $^{18}$F-fluoromisonidazole radio-tracer was conducted with the developed PET/EPRI system. We report the development and initial imaging results obtained from the PET/EPRI combined imaging system., Comment: 12 pages, 6 figures
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- 2021
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6. Single-dose radiotherapy disables tumor cell homologous recombination via ischemia/reperfusion injury
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Bodo, Sahra, Campagne, Cécile, Thin, Tin Htwe, Higginson, Daniel S, Vargas, H Alberto, Hua, Guoqiang, Fuller, John D, Ackerstaff, Ellen, Russell, James, Zhang, Zhigang, Klingler, Stefan, Cho, HyungJoon, Kaag, Matthew G, Mazaheri, Yousef, Rimner, Andreas, Manova-Todorova, Katia, Epel, Boris, Zatcky, Joan, Cleary, Cristian R, Rao, Shyam S, Yamada, Yoshiya, Zelefsky, Michael J, Halpern, Howard J, Koutcher, Jason A, Cordon-Cardo, Carlos, Greco, Carlo, Haimovitz-Friedman, Adriana, Sala, Evis, Powell, Simon N, Kolesnick, Richard, and Fuks, Zvi
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Genetics ,Cancer ,Animals ,Cell Line ,Tumor ,Chromatin ,Homologous Recombination ,Humans ,Mice ,Neoplasm Proteins ,Neoplasms ,Reperfusion Injury ,Signal Transduction ,Small Ubiquitin-Related Modifier Proteins ,Ubiquitins ,DNA repair ,Oncology ,Vascular Biology ,Medical and Health Sciences ,Immunology - Abstract
Tumor cure with conventional fractionated radiotherapy is 65%, dependent on tumor cell-autonomous gradual buildup of DNA double-strand break (DSB) misrepair. Here we report that single-dose radiotherapy (SDRT), a disruptive technique that ablates more than 90% of human cancers, operates a distinct dual-target mechanism, linking acid sphingomyelinase-mediated (ASMase-mediated) microvascular perfusion defects to DNA unrepair in tumor cells to confer tumor cell lethality. ASMase-mediated microcirculatory vasoconstriction after SDRT conferred an ischemic stress response within parenchymal tumor cells, with ROS triggering the evolutionarily conserved SUMO stress response, specifically depleting chromatin-associated free SUMO3. Whereas SUMO3, but not SUMO2, was indispensable for homology-directed repair (HDR) of DSBs, HDR loss of function after SDRT yielded DSB unrepair, chromosomal aberrations, and tumor clonogen demise. Vasoconstriction blockade with the endothelin-1 inhibitor BQ-123, or ROS scavenging after SDRT using peroxiredoxin-6 overexpression or the SOD mimetic tempol, prevented chromatin SUMO3 depletion, HDR loss of function, and SDRT tumor ablation. We also provide evidence of mouse-to-human translation of this biology in a randomized clinical trial, showing that 24 Gy SDRT, but not 3×9 Gy fractionation, coupled early tumor ischemia/reperfusion to human cancer ablation. The SDRT biology provides opportunities for mechanism-based selective tumor radiosensitization via accessing of SDRT/ASMase signaling, as current studies indicate that this pathway is tractable to pharmacologic intervention.
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- 2019
7. Fast dynamic electron paramagnetic resonance (EPR) oxygen imaging using low-rank tensors
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Christodoulou, Anthony G, Redler, Gage, Clifford, Bryan, Liang, Zhi-Pei, Halpern, Howard J, and Epel, Boris
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Engineering ,Cancer ,Biomedical Imaging ,Bioengineering ,Algorithms ,Animals ,Electron Spin Resonance Spectroscopy ,Hypoxia ,Image Processing ,Computer-Assisted ,Mice ,Neoplasms ,Oxygen ,EPR ,Imaging ,Sparse sampling ,Physical Sciences ,Biophysics ,Physical sciences - Abstract
Hypoxic tumors are resistant to radiotherapy, motivating the development of tools to image local oxygen concentrations. It is generally believed that stable or chronic hypoxia is the source of resistance, but more recent work suggests a role for transient hypoxia. Conventional EPR imaging (EPRI) is capable of imaging tissue pO2in vivo, with high pO2 resolution and 1mm spatial resolution but low imaging speed (10min temporal resolution for T1-based pO2 mapping), which makes it difficult to investigate the oxygen changes, e.g., transient hypoxia. Here we describe a new imaging method which accelerates dynamic EPR oxygen imaging, allowing 3D imaging at 2 frames per minute, fast enough to image transient hypoxia at the "speed limit" of observed pO2 change. The method centers on a low-rank tensor model that decouples the tradeoff between imaging speed, spatial coverage/resolution, and number of inversion times (pO2 accuracy). We present a specialized sparse sampling strategy and image reconstruction algorithm for use with this model. The quality and utility of the method is demonstrated in simulations and in vivo experiments in tumor bearing mice.
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- 2016
8. Corrigendum: Absolute oxygen-guided radiation therapy improves tumor control in three preclinical tumor models
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Gertsenshteyn, Inna, primary, Epel, Boris, additional, Giurcanu, Mihai, additional, Barth, Eugene, additional, Lukens, John, additional, Hall, Kayla, additional, Martinez, Jenipher Flores, additional, Grana, Mellissa, additional, Maggio, Matthew, additional, Miller, Richard C., additional, Sundramoorthy, Subramanian V., additional, Krzykawska-Serda, Martyna, additional, Pearson, Erik, additional, Aydogan, Bulent, additional, Weichselbaum, Ralph R., additional, Tormyshev, Victor M., additional, Kotecha, Mrignayani, additional, and Halpern, Howard J., additional
- Published
- 2023
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9. Absolute oxygen-guided radiation therapy improves tumor control in three preclinical tumor models
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Gertsenshteyn, Inna, primary, Epel, Boris, additional, Giurcanu, Mihai, additional, Barth, Eugene, additional, Lukens, John, additional, Hall, Kayla, additional, Martinez, Jenipher Flores, additional, Grana, Mellissa, additional, Maggio, Matthew, additional, Miller, Richard C., additional, Sundramoorthy, Subramanian V., additional, Krzykawska-Serda, Martyna, additional, Pearson, Erik, additional, Aydogan, Bulent, additional, Weichselbaum, Ralph R., additional, Tormyshev, Victor M., additional, Kotecha, Mrignayani, additional, and Halpern, Howard J., additional
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- 2023
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10. HIF-stabilizing Biomaterials: from Hypoxia-mimicking to Hypoxia-inducing
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Colombani, Thibault, primary, Bhatt, Khushbu, additional, Epel, Boris, additional, Kotecha, Mrignayani, additional, and Bencherif, Sidi A., additional
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- 2023
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11. A bioinspired scaffold for rapid oxygenation of cell encapsulation systems
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Wang, Long-Hai, primary, Ernst, Alexander Ulrich, additional, An, Duo, additional, Datta, Ashim Kumar, additional, Epel, Boris, additional, Kotecha, Mrignayani, additional, and Ma, Minglin, additional
- Published
- 2021
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12. Highly sensitive electron paramagnetic resonance nanoradicals for quantitative intracellular tumor oxymetric images
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Chen,Nai-Tzu, Barth,Eugene D., Lee,Tsung-Hsi, Chen,Chin-Tu, Epel,Boris, Halpern,Howard, and Lo,Leu-Wei
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Male ,Free Radicals ,Electron Spin Resonance Spectroscopy ,Mice, Nude ,Silicon Dioxide ,tumor oxygenation ,Fluorescence ,Oxygen ,triarylmethyl (trityl) spin probe ,Imaging, Three-Dimensional ,Oxygen Consumption ,International Journal of Nanomedicine ,mesoporous silica nanoparticles (MSNs) ,Cell Line, Tumor ,Neoplasms ,Animals ,Humans ,Nanoparticles ,electron paramagnetic resonance imaging (EPRI) ,Oximetry ,Porosity ,Original Research - Abstract
Nai-Tzu Chen,1 Eugene D Barth,2,3 Tsung-Hsi Lee,4 Chin-Tu Chen,5 Boris Epel,2,3 Howard J Halpern,2,3 Leu-Wei Lo5,61Institute of New Drug Development, China Medical University, Taichung 40402, Taiwan; 2Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL 60637, USA; 3Center for EPR Imaging In Vivo Physiology, University of Chicago, Chicago, IL 60637, USA; 4Department of Biological Science and Technology, China Medical University, Taichung 40402, Taiwan; 5Department of Radiology, University of Chicago, Chicago, IL 60637 USA; 6Institute of Biomedical Engineering and Nanomedicine, National Health Research Institutes, Zhunan 35053, TaiwanPurpose: Tumor oxygenation is a critical parameter influencing the efficacy of cancer therapy. Low levels of oxygen in solid tumor have been recognized as an indicator of malignant progression and metastasis, as well as poor response to chemo- and radiation therapy. Being able to measure oxygenation for an individual’s tumor would provide doctors with a valuable way of identifying optimal treatments for patients.Methods: Electron paramagnetic resonance imaging (EPRI) in combination with an oxygen-measuring paramagnetic probe was performed to measure tumor oxygenation in vivo. Triarylmethyl (trityl) radical exhibits high specificity, sensitivity, and resolution for quantitative measurement of O2 concentration. However, its in vivo applications in previous studies have been limited by the required high dosage, its short half-life, and poor intracellular permeability. To address these limitations, we developed high-capacity nanoformulated radicals that employed fluorescein isothiocyanate-labeled mesoporous silica nanoparticles (FMSNs) as trityl radical carriers. The high surface area nanostructure and easy surface modification of physiochemical properties of FMSNs enable efficient targeted delivery of highly concentrated, nonself-quenched trityl radicals, protected from environmental degradation and dilution.Results: We successfully designed and synthesized a tumor-targeted nanoplatform as a carrier for trityl. In addition, the nanoformulated trityl does not affect oxygen-sensing capacity by a self-relaxation or broadening effect. The FMSN-trityl exhibited high sensitivity/response to oxygen in the partial oxygen pressure range from 0 to 155 mmHg. Furthermore, MSN-trityl displayed outstanding intracellular oxygen mapping in both in vitro and in vivo animal studies.Conclusion: The highly sensitive nanoformulated trityl spin probe can profile intracellular oxygen distributions of tumor in a real-time and quantitative manner using in vivo EPRI.Keywords: tumor oxygenation, electron paramagnetic resonance imaging (EPRI), mesoporous silica nanoparticles (MSNs), triarylmethyl (trityl) spin probe
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- 2019
13. An inverse-breathing encapsulation system for cell delivery
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Wang, Long-Hai, primary, Ernst, Alexander Ulrich, additional, Flanders, James Arthur, additional, Liu, Wanjun, additional, Wang, Xi, additional, Datta, Ashim K., additional, Epel, Boris, additional, Kotecha, Mrignayani, additional, Papas, Klearchos K., additional, and Ma, Minglin, additional
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- 2021
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14. Improving Tumor Hypoxia Location in 18F-Misonidazole PET with Dynamic Contrast-enhanced MRI Using Quantitative Electron Paramagnetic Resonance Partial Oxygen Pressure Images
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Gertsenshteyn, Inna, primary, Epel, Boris, additional, Barth, Eugene, additional, Leoni, Lara, additional, Markiewicz, Erica, additional, Tsai, Hsiu-Ming, additional, Fan, Xiaobing, additional, Giurcanu, Mihai, additional, Bodero, Darwin, additional, Zamora, Marta, additional, Sundramoorthy, Subramanian, additional, Kim, Heejong, additional, Freifelder, Richard, additional, Bhuiyan, Mohammed, additional, Kucharski, Anna, additional, Karczmar, Gregory, additional, Kao, Chien-Min, additional, Halpern, Howard, additional, and Chen, Chin-Tu, additional
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- 2021
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15. Abstract 2773: Increased tumor control boosting hypoxic regions identified with EPR pO2 imaging in 2 tumor types
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Halpern, Howard, primary, Maggio, Matthew, additional, Barth, Eugene, additional, Bodero, Darwin, additional, Miller, Richard C., additional, Pelizzari, Charles A., additional, Krzykawska-Serda, Martyna, additional, Sundramoorthy, Subramanian V., additional, Aydogan, Bulent, additional, Weichselbaum, Ralph R., additional, Tormyshev, Victor M., additional, Gertsenshteyn, Inna, additional, and Epel, Boris, additional
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- 2020
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16. Abstract 1648: Multimodal imaging of tumor hypoxia with 18F-misonidazole PET, EPR, and MRI
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Gertsenshteyn, Inna, primary, Epel, Boris, additional, Leoni, Lara, additional, Fan, Xiaobing, additional, Friefelder, Richard, additional, Barth, Eugene, additional, Kim, Heejong, additional, Zamora, Marta, additional, Markiewicz, Erica, additional, Bodero, Darwin, additional, Bhuiyan, Mohammed, additional, Kucharski, Anna, additional, Tsai, Hsiu-Ming, additional, Grana, Mellissa, additional, Sundramoorthy, Subramanian V., additional, Karczmar, Gregory S., additional, Kao, Chien-Min, additional, Chen, Chin-Tu, additional, and Halpern, Howard, additional
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- 2020
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17. A Doubly Constrained TV Algorithm for Image Reconstruction
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Qiao, Zhiwei, primary, Redler, Gage, additional, Epel, Boris, additional, and Halpern, Howard, additional
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- 2020
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18. Phylloquinone and related radical anions studied by pulse electron nuclear double resonance spectroscopy at 34 GHz and density functional theory
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Epel, Boris, Niklas, Jens, Sinnecker, Sebastian, Zimmermann, Herbert, and Lubitz, Wolfgang
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Propanols -- Chemical properties ,Hydrogen bonding -- Chemical properties ,Hydrogen bonding -- Spectra ,Quinone -- Chemical properties ,Quinone -- Spectra ,Chemicals, plastics and rubber industries - Abstract
The semiquninone radical anions B[Q.sup..-], N[Q.sup..-], V[K3.sup..-] and V[K1.sup..-] in frozen propanol solution is measured using pulsed Q-band electron nuclear double resonance spectroscopy. The hyperfine (hf) tensors study concluded that four solvent molecules are coordinated through hydrogen bonds to the quinone oxygens but in V[K3.sup..-] and V[K1.sup..-] some of these hydrogen bonds do not lie in the plane of the quinone.
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- 2006
19. Real-Time Image Reconstruction for Pulse EPR Oxygen Imaging Using a GPU and Lookup Table Parameter Fitting
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Redler, Gage, Qiao, Zhiwei, Epel, Boris, and Halpern, Howard J.
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Article - Abstract
The importance of tissue oxygenation has led to a great interest in methods for imaging pO2 in vivo. Electron paramagnetic resonance imaging (EPRI) provides noninvasive, near absolute 1 mm-resolved 3D images of pO2 in the tissues and tumors of living animals. Current EPRI image reconstruction methods tend to be time consuming and preclude real-time visualization of information. Methods are presented to significantly accelerate the reconstruction process in order to enable real-time reconstruction of EPRI pO2 images. These methods are image reconstruction using graphics processing unit (GPU)-based 3D filtered back-projection and lookup table parameter fitting. The combination of these methods leads to acceleration factors of over 650 compared to current methods and allows for real-time reconstruction of EPRI images of pO2 in vivo.
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- 2015
20. In vivo pO2 imaging of tumors: Oxymetry with very low frequency Electron Paramagnetic Resonance
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Epel, Boris and Halpern, Howard J.
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inorganic chemicals ,Oxygen ,Neoplasms ,Electron Spin Resonance Spectroscopy ,Animals ,Humans ,Oximetry ,Hypoxia ,Article - Abstract
For over a century, it has been known that tumor hypoxia, regions of a tumor with low levels of oxygenation, are important contributors to tumor resistance to radiation therapy and failure of radiation treatment of cancer. Recently, using novel pulse electron paramagnetic resonance (EPR) oxygen imaging, near absolute images of the partial pressure of oxygen (pO2) in tumors of living animals have been obtained. We discuss here the means by which EPR signals can be obtained in living tissues and tumors. We review development of EPR methods to image the pO2 in tumors and the potential for the pO2 image acquisition in human subjects.
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- 2015
21. Highly sensitive electron paramagnetic resonance nanoradicals for quantitative intracellular tumor oxymetric images.
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Nai-Tzu Chen, Barth, Eugene D., Tsung-Hsi Lee, Chin-Tu Chen, Epel, Boris, Halpern, Howard J., and Leu-Wei Lo
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- 2019
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22. What We Learn From Oxygen Images
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Redler, Gage, Epel, Boris, and Halpern, Howard J.
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Mice, Knockout ,Mitochondrial Proteins ,Oxygen ,Mice ,Mammary Tumor Virus, Mouse ,Antigens, Polyomavirus Transforming ,Electron Spin Resonance Spectroscopy ,Animals ,Mammary Neoplasms, Experimental ,Membrane Proteins ,Article - Abstract
Distributions of oxygen concentration (pO₂) are a critical determinant of normal tissue health as well as tumor aggressiveness and response to therapy. A number of studies show the value of normal tissue and tumor tissue oxygenation images and some of these will be discussed here. A strong correlation between tumor hypoxic fraction as measured with electron paramagnetic resonance oxygen imaging and radiation treatment success or failure has been found in two separate cancer types. Oxygen images of the torso of wild type mice show initial reduction of lung, liver, visceral, and muscle pO₂ with cyclic halving of fraction of inspired oxygen (FiO₂), but variation is blunted over an hour. Spontaneous breast cancers in Mouse Mammary Tumor Viral (MMTV) promoted-polyoma middle T antigen (PyMT) mice with BNIP3, a major factor in promotion of mitochondrial autophagy, knocked out will be compared with wild type animals. Preliminary studies for the BNIP3 knock out animals show extremely low pO₂. The wide variety of studies, in which oxygen images can play an integral role, serve to demonstrate the importance of oxygen images.
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- 2014
23. Electron paramagnetic resonance oxygen imaging of a rabbit tumor using localized spin probe delivery
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Epel, Boris, Haney, Chad R., Hleihel, Danielle, Wardrip, Craig, Barth, Eugene D., and Halpern, Howard J.
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Oxygen ,Drug Delivery Systems ,Tissue Measurements ,Carcinoma ,Electron Spin Resonance Spectroscopy ,Animals ,Contrast Media ,Spin Labels ,Rabbits ,Image Enhancement ,Magnetic Resonance Imaging - Abstract
Application of in vivo electron paramagnetic resonance (EPR) oxygen imaging (EPROI) to tumors larger than those of mice requires development of both instrumental and medical aspects of imaging.250 MHz EPR oxygen imaging was performed using a loop-gap resonator with a volume exceeding 100 cm3. The paramagnetic spin probe was injected directly into the femoral artery feeding the rabbit leg/tumor.The authors present continuous wave and electron spin echo EPR oxygen images of a large size (4 cm) VX-2 tumor located on the leg of a New Zealand white rabbit.This study demonstrates the feasibility of continuous wave and electron spin echo oxygen imaging modalities for investigation of volumes of tumor and normal tissue relevant to large animals. The injection of the spin probe directly into the artery feeding a rabbit leg will allow one to reduce, by over one order of magnitude, the amount of spin probe used as compared to whole animal i.v. injection.
- Published
- 2010
24. A passive dual-circulator based transmit/receive switch for use with reflection resonators in pulse EPR
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Subramanian, V. S., Epel, Boris, Mailer, Colin, and Halpern, Howard J.
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Article - Abstract
In order to protect the low noise amplifier (LNA) in the receive arm of a pulsed 250 MHz EPR bridge, it is necessary to install as much isolation as possible between the power exciting the spin system and the LNA when high power is present in the receive arm of the bridge, while allowing the voltage induced by the magnetization in the spin sample to be passed undistorted and undiminished to the LNA once power is reduced below the level that can cause a LNA damage. We discuss a combination of techniques to accomplish this involving the power-routing circulator in the bridge, a second circulator acting as an isolator with passive shunt PIN diodes immediately following the second circulator. The low resistance of the forward biased PIN diode passively generates an impedance mismatch at the second circulator output port during the high power excitation pulse and resonator ring down. The mismatch reflects the high power to the remaining port of the second circulator, dumping it into a system impedance matched load. Only when the power diminishes below the diode conduction threshold will the resistance of the PIN diode rise to a value much higher than the system impedance. This brings the device into conduction mode. We find that the present design passively limits the output power to 14 dBm independent of the input power. For high input power levels the isolation may exceed 60 dB. This level of isolation is sufficient to fully protect the LNA of pulse EPR bridge.
- Published
- 2009
25. EPR Oxygen Images Predict Tumor Control by a 50% Tumor Control Radiation Dose
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Elas, Martyna, primary, Magwood, Jessica M., additional, Butler, Brandi, additional, Li, Chanel, additional, Wardak, Rona, additional, DeVries, Rebekah, additional, Barth, Eugene D., additional, Epel, Boris, additional, Rubinstein, Samuel, additional, Pelizzari, Charles A., additional, Weichselbaum, Ralph R., additional, and Halpern, Howard J., additional
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- 2013
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26. Synthesis and characterization of de novo designed peptides modelling the binding sites of [4Fe–4S] clusters in photosystem I
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Antonkine, Mikhail L., primary, Koay, Melissa S., additional, Epel, Boris, additional, Breitenstein, Christoph, additional, Gopta, Oxana, additional, Gärtner, Wolfgang, additional, Bill, Eckhard, additional, and Lubitz, Wolfgang, additional
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- 2009
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27. Electronic Structure of the Quinone Radical Anion A1•−of Photosystem I Investigated by Advanced Pulse EPR and ENDOR Techniques
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Niklas, Jens, primary, Epel, Boris, additional, Antonkine, Mikhail L., additional, Sinnecker, Sebastian, additional, Pandelia, Maria-Eirini, additional, and Lubitz, Wolfgang, additional
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- 2009
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28. An inverse-breathing encapsulation system for cell delivery.
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Long-Hai Wang, Ernst, Alexander Ulrich, Flanders, James Arthur, Wanjun Liu, Xi Wang, Datta, Ashim K., Epel, Boris, Kotecha, Mrignayani, Papas, Klearchos K., and Minglin Ma
- Subjects
- *
RESPIRATION , *ISLANDS of Langerhans , *POLYMERSOMES , *BIOENGINEERING , *ELECTRON spin echoes , *KINETIC theory of gases - Published
- 2021
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29. EPR Oxygen Images Predict Tumor Control by a 50%Tumor Control Radiation Dose.
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Elas, Martyna, Magwood, Jessica M., Butler, Brandi, Chanel Li, Wardak, Rona, Barth, Eugene D., Epel, Boris, Rubinstein, Samuel, Pelizzari, Charles A., Weichselbaum, Ralph R., and Halpern, Howard J.
- Subjects
- *
TUMOR diagnosis , *HYPOXEMIA , *LABORATORY mice , *FIBROSARCOMA , *KAPLAN-Meier estimator - Abstract
Clinical trials to ameliorate hypoxia as a strategy to relieve the radiation resistance it causes have prompted a need to assay the precise extent and location of hypoxia in tumors. Electron paramagnetic resonance oxygen imaging (EPR O2 imaging) provides a noninvasive means to address this need. To obtain a preclinical proof-of-principle that EPR O2 images could predict radiation control, we treatedmouse tumors at or near doses required to achieve 50% control (TCD50). Mice with FSa fibrosarcoma or MCa4 carcinoma were subjected to EPR O2 imaging and immediately radiated to a TCD50 or TCD50 10Gy. Statistical analysiswas permitted by collection of approximately 1,300 tumor pO2 image voxels, including the fraction of tumor voxels with pO2 less than 10mmHg (HF10). Tumors were followed for 90 days (FSa) or 120 days (MCa4) to determine local control or failure. HF10 obtained fromEPR images showed statistically significant differences between tumors thatwere controlled by the TCD50 and those that were not controlled for both FSa andMCa4. Kaplan-Meier analysis of both types of tumors showed that approximately 90%ofmildly hypoxic tumorswere controlled (HF10% 10%), and only 37%(FSA) and 23% (MCa4) tumors controlled if hypoxic. EPR pO2 image voxel distributions in these approximately 0.5 mL tumors provide a prediction of radiation curability independent of radiation dose. These data confirm the significance of EPR pO2 hypoxic fractions. The 90% control of low HF10 tumors argue that 0.5 mL subvolumes of tumors may be more sensitive to radiation and may need less radiation for high tumor control rates. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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30. Improving Tumor Hypoxia Location in 18 F-Misonidazole PET with Dynamic Contrast-enhanced MRI Using Quantitative Electron Paramagnetic Resonance Partial Oxygen Pressure Images.
- Author
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Gertsenshteyn I, Epel B, Barth E, Leoni L, Markiewicz E, Tsai HM, Fan X, Giurcanu M, Bodero D, Zamora M, Sundramoorthy S, Kim H, Freifelder R, Bhuiyan M, Kucharski A, Karczmar G, Kao CM, Halpern H, and Chen CT
- Subjects
- Animals, Electron Spin Resonance Spectroscopy, Hypoxia diagnostic imaging, Magnetic Resonance Imaging, Mice, Oxygen, Positron Emission Tomography Computed Tomography, Positron-Emission Tomography, Misonidazole, Tumor Hypoxia
- Abstract
Purpose: To enhance the spatial accuracy of fluorine 18 (
18 F) misonidazole (MISO) PET imaging of hypoxia by using dynamic contrast-enhanced (DCE) MR images as a basis for modifying PET images and by using electron paramagnetic resonance (EPR) partial oxygen pressure (pO2 ) as the reference standard., Materials and Methods: Mice ( n = 10) with leg-borne MCa4 mammary carcinomas underwent EPR imaging, T2-weighted and DCE MRI, and18 F-MISO PET/CT. Images were registered to the same space for analysis. The thresholds of hypoxia for PET and EPR images were tumor-to-muscle ratios greater than or equal to 2.2 mm Hg and less than or equal to 14 mm Hg, respectively. The Dice similarity coefficient (DSC) and Hausdorff distance (dH ) were used to quantify the three-dimensional overlap of hypoxia between pO2 EPR and18 F-MISO PET images. A training subset ( n = 6) was used to calculate optimal DCE MRI weighting coefficients to relate EPR to the PET signal; the group average weights were then applied to all tumors (from six training mice and four test mice). The DSC and dH were calculated before and after DCE MRI-corrected PET images were obtained to quantify the improvement in overlap with EPR pO2 images for measuring tumor hypoxia., Results: The means and standard deviations of the DSC and dH between hypoxic regions in original PET and EPR images were 0.35 mm ± 0.23 and 5.70 mm ± 1.7, respectively, for images of all 10 mice. After implementing a preliminary DCE MRI correction to PET data, the DSC increased to 0.86 mm ± 0.18 and the dH decreased to 2.29 mm ± 0.70, showing significant improvement ( P < .001) for images of all 10 mice. Specifically, for images of the four independent test mice, the DSC improved with correction from 0.19 ± 0.28 to 0.80 ± 0.29 ( P = .02), and the dH improved from 6.40 mm ± 2.5 to 1.95 mm ± 0.63 ( P = .01)., Conclusion: Using EPR information as a reference standard, DCE MRI information can be used to correct18 F-MISO PET information to more accurately reflect areas of hypoxia. Keywords: Animal Studies, Molecular Imaging, Molecular Imaging-Cancer, PET/CT, MR-Dynamic Contrast Enhanced, MR-Imaging, PET/MR, Breast, Oncology, Tumor Mircoenvironment, Electron Paramagnetic Resonance Supplemental material is available for this article. © RSNA, 2021., Competing Interests: Disclosures of Conflicts of Interest: I.G. disclosed no relevant relationships. B.E. Activities related to the present article: disclosed no relevant relationships. Activities not related to the present article: disclosed no relevant relationships. Other relationships: co-owner of O2M Technologies, a company that fabricates EPR imaging instruments. No O2M instruments, IP, or technology was used in the present work. E.B. disclosed no relevant relationships. L.L. disclosed no relevant relationships. E.M. disclosed no relevant relationships. H.M.T. disclosed no relevant relationships. X.F. disclosed no relevant relationships. M.G. disclosed no relevant relationships. D.B. Activities related to the present article: National Cancer Institute grant R01CA236385 was used to partially fund the author’s salary for this project. Activities not related to the present article: money from O2M Technologies paid was part of the author’s transition to employment with O2M. These funds were not a part of the relevant work. Other relationships: disclosed no relevant relationships. M.Z. disclosed no relevant relationships. S.S. disclosed no relevant relationships. H.K. disclosed no relevant relationships. R.F. disclosed no relevant relationships. M.B. disclosed no relevant relationships. A.K. disclosed no relevant relationships. G.K. disclosed no relevant relationships. C.M.K. disclosed no relevant relationships. H.H. Activities related to the present article: disclosed no relevant relationships. Activities not related to the present article: disclosed no relevant relationships. Other relationships: Inventor of several patents, including Magnetic Resonance Analysis of Substances in Samples that Include Dissipative Material (inventor: Howard Halpern; patent no.: 4,714,886); Selective Isotopic Labelling of Spin Labels for Electron Resonance Spectroscopy (inventors: Howard Halpern, Beverly A. Teicher; patent no.: 5,431,901) Imaging system performing substantially exact reconstruction and using non-traditional trajectories (inventors: Pan X, Zou, Yu, Yu L, Kao; C-M, King M, Giger M, Xia D, Halpern H, Pelizzari C, Sidky E, Cho S; patent no: 7,444,011); High isolation transmit/receive surface coils and method for EPRI (inventor: Halpern H; patent no. 8,644,955); T1-Senstivie inversion recovery-imaging method and apparatus for EPRI (inventors: Halpern H, Epel B; patent no.: 9,392,957); Method and apparatus for resonator signal production and measurement (inventors: Halpern H, Sundramoorthy S, Epel B; patent no.:10,551,450B2); Method and high isolation transmit/receive surface coils for EPRI (inventor: Howard J. Halpern; patent no.: 10,568,537); and Alderman-Grant/Loop-Gap High Isolation Crossed Field Bimodal Resonator (inventors: Halpern H, Epel B, Sundramoorthy S; submitted: 4/12/2011). C.T.C. Activities related to the present article: disclosed no relevant relationships. Activities not related to the present article: royalties and stock options from RefleXion Medical, which is licensed from the University of Chicago for the author’s patent on PET or SPECT-guided radiation therapy. Other relationships: disclosed no relevant relationships., (2021 by the Radiological Society of North America, Inc.)- Published
- 2021
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31. Electronic structure of the quinone radical anion A1*- of photosystem I investigated by advanced pulse EPR and ENDOR techniques.
- Author
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Niklas J, Epel B, Antonkine ML, Sinnecker S, Pandelia ME, and Lubitz W
- Subjects
- Binding Sites, Coenzymes chemistry, Coenzymes metabolism, Cyanobacteria enzymology, Electron Spin Resonance Spectroscopy, Hydrogen Bonding, Models, Molecular, Organic Chemicals chemistry, Protein Conformation, Protons, Quantum Theory, Solvents chemistry, Vitamin K 1 metabolism, Electrons, Photosystem I Protein Complex metabolism, Vitamin K 1 chemistry
- Abstract
Vitamin K1 (VK1) is an important cofactor of the electron-transfer chain in photosystem I (PS I), referred to as A1. The special properties of this quinone result from its unique interaction(s) with the protein surrounding. In particular, a single H-bond to neutral A1 was identified previously in the X-ray crystal structure of PS I. During light-induced electron transfer in PS I, A1 is transiently reduced to the radical anion A1*-. In this work, we characterized the electron spin density distribution of A1*- with the aim of understanding the influence of the protein surrounding on it. We studied the light-induced spin-polarized radical pair P700*+A1*- and the photoaccumulated radical anion A1*-, using advanced pulse EPR, ENDOR, and TRIPLE techniques at Q-band (34 GHz). Exchange with fully deuterated quinone in the A1 binding site allowed differentiation between proton hyperfine couplings from the quinone and from the protein surrounding. In addition, DFT calculations on a model of the A1 site were performed and provided proton hyperfine couplings that were in close agreement with the ones determined experimentally. This combined approach allowed the assignment of proton hyperfine coupling tensors to molecular positions, thereby yielding a picture of the spin density distribution in A1*-. Comparison with VK1*- in organic solvents (Epel et al. J. Phys. Chem. B 2006, 110, 11549.) leads to the conclusion that the single H-bond present in both the radical pair P700*+A1*- and the photoaccumulated radical anion A1*- is, indeed, the crucial factor that governs the electronic structure of A1*-.
- Published
- 2009
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