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156 results on '"Kotecha, Mrignayani"'

9. Assessment of blood-brain barrier leakage and brain oxygenation in Connexin-32 knockout mice with systemic neuroinflammation using pulse electron paramagnetic resonance imaging techniques.

Author

Epel, Boris, Viswakarma, Navin, Hameed, Safa, Freidin, Mona M., Abrams, Charles K., and Kotecha, Mrignayani

Subjects
ELECTRON paramagnetic resonance, BLOOD-brain barrier, KNOCKOUT mice, ELECTRON spin echoes, NEUROINFLAMMATION
Abstract

Purpose: The determination of blood-brain barrier (BBB) integrity and partial pressure of oxygen (pO2) in the brain is of substantial interest in several neurological applications. This study aimed to assess the feasibility of using trityl OX071-based pulse electron paramagnetic resonance imaging (pEPRI) to provide a quantitative estimate of BBB integrity and pO2 maps in mouse brains as a function of neuroinflammatory disease progression. Methods: Five Connexin-32 (Cx32)-knockout (KO) mice were injected with lipopolysaccharide to induce neuroinflammation for imaging. Three wild-type mice were also used to optimize the imaging procedure and as control animals. An additional seven Cx32-KO mice were used to establish the BBB leakage of trityl using the colorimetric assay. All pEPRI experiments were performed using a preclinical instrument, JIVA-25 (25mT/720 MHz), at times t =0, 4, and 6 h following lipopolysaccharide injection. Two pEPRI imaging techniques were used: (a) single-point imaging for obtaining spatial maps to outline the brain and calculate BBB leakage using the signal amplitude, and (b) inversion-recovery electron spin echo for obtaining pO2 maps. Results: A statistically significant change in BBB leakage was found using pEPRI with the progression of inflammation in Cx32 KO animals. However, the change in pO2 values with the progression of inflammation for these animals was not statistically significant. Conclusions: For the first time, we show the ability of pEPRI to provide pO2 maps in mouse brains noninvasively, along with a quantitative assessment of BBB leakage. We expect this study to open new queries from the field to explore the pathology of many neurological diseases and provide a path to new treatments. [ABSTRACT FROM AUTHOR]

Published
2024
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10. Inflammation-induced subcutaneous neovascularization for the long-term survival of encapsulated islets without immunosuppression

Author

Wang, Long-Hai, primary, Marfil-Garza, Braulio A., additional, Ernst, Alexander U., additional, Pawlick, Rena L., additional, Pepper, Andrew R., additional, Okada, Kento, additional, Epel, Boris, additional, Viswakarma, Navin, additional, Kotecha, Mrignayani, additional, Flanders, James Arthur, additional, Datta, Ashim K., additional, Gao, Hong-Jie, additional, You, Ye-Zi, additional, Ma, Minglin, additional, and Shapiro, A. M. James, additional

Published
2023
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11. Corrigendum: Absolute oxygen-guided radiation therapy improves tumor control in three preclinical tumor models

Author

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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12. SOX71, A Biocompatible Succinyl Derivative of the Triarylmethyl Radical OX071 for In Vivo Quantitative Oxygen Mapping Using Electron Paramagnetic Resonance

Author

Shaw, Misa A., primary, Poncelet, Martin, additional, Viswakarma, Navin, additional, Vallerini, Gian Paolo, additional, Hameed, Safa, additional, Gluth, Teresa D., additional, Geldenhuys, Werner J., additional, Hoblitzell, Emily H., additional, Eubank, Timothy D., additional, Epel, Boris, additional, Kotecha, Mrignayani, additional, and Driesschaert, Benoit, additional

Published
2023
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13. Absolute oxygen-guided radiation therapy improves tumor control in three preclinical tumor models

Author

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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14. Evaluating Tumor Hypoxia Radiosensitization Via Electron Paramagnetic Resonance Oxygen Imaging (EPROI)

Author

Rickard, Ashlyn G., primary, Mowery, Yvonne M., additional, Bassil, Alex, additional, Rouse, Douglas C., additional, Williams, Nerissa T., additional, Charity, Theresa, additional, Belloni, Rafaela, additional, Crouch, Brian, additional, Ramanujam, Nimmi, additional, Stevenson, Daniel, additional, Castillo, Rico, additional, Blocker, Stephanie, additional, Epel, Boris, additional, Kotecha, Mrignayani, additional, and Palmer, Gregory M., additional

Published
2023
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17. Estimation of Domain Size in Nano Ferroelectrics from NMR T1 Measurements

Author

Shukla, Alok, Kotecha, Mrignayani, and Pandey, Lakshman

Subjects
Condensed Matter - Materials Science, Condensed Matter - Other Condensed Matter, Physics - Chemical Physics
Abstract

The spin lattice relaxation of I=3/2 quadrupolar spin system due to domain walls in order-disorder ferroelectrics has been studied and a general method is proposed for the measurement of domain width in nano ferroelectrics. Based on the fact that electric polarization undergoes spiral orientation as one moves from one domain to the other, it is assumed that at low temperatures the spins at and near domain walls undergo relaxation due to possible easy reorientation of electric polarization in domain walls even though such a relaxation in the main body of the domain has almost ceased. The spins present inside the domain undergo relaxation through transfer of magnetization to the domain walls through a spin diffusion process by nearest neighbour interaction. Rate equations for spin populations are formed by representing the ferroelectric domain by a one-dimensional chain of equidistant spins having dipolar coupling. Spin populations are calculated as a function of time for different ratios of quadrupolar to dipolar transition probabilities for a sample subjected to selective rf pulse. Expression for spin- lattice relaxation time T1 is derived in terms of domain width and ratio of quadrupolar to dipolar transition probabilities. It is found that the domain width can be estimated provided the value of spin lattice relaxation time T1 is known for the corresponding crystal with normal sized grains. The results are quite general and can be applied to any order disorder ferroelectric with nano sized domains and having spin I=3/2 nuclei., Comment: 31 pages, 5 figures, 1 table

Published
2008

29. An inverse-breathing encapsulation system for cell delivery

Author

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

Published
2021
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31. In VivoPartial Oxygen Pressure Assessment in Subcutaneous and Intraperitoneal Sites Using Imaging of Solid Oxygen Probe

Author

Viswakarma, Navin, Siddiqui, Eliyas, Patel, Sonny, Hameed, Safa, Schreiber, Wilson, Swartz, Harold M., Epel, Boris, and Kotecha, Mrignayani

Abstract

The purpose of this study was to assess the natural partial oxygen pressure (pO2) of subcutaneous (SC) and intraperitoneal (IP) sites in mice to determine their relative suitability as sites for placement of implants. The pO2measurements were performed using oxygen imaging of solid probes using lithium phthalocyanine (LiPc) as the oxygen sensitive material. LiPc is a water-insoluble crystalline probe whose spin–lattice and spin–spin relaxation rates (R1and R2) are sensitive to the local oxygen concentration. To facilitate direct in vivooxygen imaging, we prepared a solid probe containing encapsulated LiPc crystals in polydimethylsiloxane (PDMS), an oxygen-permeable and bioinert polymer. Although LiPc-PDMS or similar probes have been used in repeated spectroscopic or average oxygen measurements using continuous wave electron paramagnetic resonance (EPR) since the late 1990s and now have advanced to clinical applications, they have not been used for pulse EPR oxygen imaging. One LiPc-PDMS probe of 2 mm diameter and 10 mm length was implanted in SC or IP sites (left or right side) in each animal. The pO2imaging of implanted LiPc-PDMS probes was performed weekly for 6 weeks using O2M preclinical 25 mT oxygen imager, JIVA-25™, using the pulse inversion recovery electron spin echo method. At week 6, the probes were recovered, and histological examinations were performed. We report in this study, first-ever solid probe oxygen imaging of implanted devices and pO2assessment of SC and IP sites.

Published
2022
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32. Relaxation-assisted separation of chemical sites in NMR spectroscopy of static solids

Author

Lupulescu, Adonis, Kotecha, Mrignayani, Frydman, Lucio, and Bowers, Michael T.

Subjects
Chemistry, Physical and theoretical -- Research, Nuclear magnetic resonance spectroscopy -- Usage, Chemistry
Abstract

The potential use of relaxation times toward the resolution of inequivalent chemical sites in the NMR spectroscopy of powdered or disordered samples is discussed. The proposal is motivated by the significant differences that could often be detected in the relaxation behavior of sites in solids.

Published
2003

40. Dynamic effects in MAS and MQMAS NMR spectra of half-integer quadrupolar nuclei: Calculations and an application to the double perovskite cryolite

Author

Kotecha, Mrignayani, Chaudhuri, Santanu, Grey, Clare P., and Frydman, Lucio

Subjects
Perovskite -- Chemical properties, Nuclear magnetic resonance -- Analysis, Lattice dynamics -- Research, Chemistry
Abstract

A description is provided about the dynamic effects of the multisided MAS (magic angle spinning) and MQMAS (multiple quantum magic angle spinning) and also relates them to evaluate the vast processes that take place in the double perovskite cryolite. Finally, the evaluation shows that synthetic cryolite lacks NaF, which leads to the existence of Na(super +) vacancy in the lattice.

Published
2005

43. The Application of Sodium Triple-Quantum Coherence NMR Spectroscopy for the Study of Growth Dynamics in Cartilage Tissue Engineering

Author

Kotecha, Mrignayani, Ravindran, Sriram, Schmid, Thomas M., Vaidyanathan, Aishwarya, George, Anne, and Magin, Richard L.

Subjects
Cartilage, Articular, Chondrocytes, Magnetic Resonance Spectroscopy, Tissue Engineering, Biomimetics, Sodium, Animals, Cattle, Article, Cells, Cultured, Cell Proliferation
Abstract

We studied the tissue growth dynamics for tissue-engineered cartilage at the early growth stage after cell seeding for four weeks using sodium triple-quantum coherence NMR spectroscopy. The following tissue-engineering constructs were studied: 1. Bovine chondrocytes cultured in alginate beads, 2. Bovine chondrocytes cultured as pellets (scaffold-free chondrocyte pellets), 3. Human Marrow Stromal Cells (HMSC) seeded in Collagen/Chitosan based scaffolds of chondrogenic extracellular matrix environment expecting chondrogenic differentiation, named as biomimetic scaffolds. We found that the sodium triple quantum coherence spectroscopy can differentiate between different tissue-engineering constructs and the native tissues based on the fast and the slow relaxation rates as well as based on the average quadrupolar coupling. Both the fast (Tf) and the slow (Ts) relaxation times were found to be longer in the chondrocyte pellets and the biomimetic scaffolds as compared to the chondrocytes suspended in alginate beads and the human articular cartilage tissues. In all cases, it was found that the relaxation rates and the motion of sodium ions, as measured from correlation time, were dependent on the amount of macromolecules, high cell density and the anisotropy of the cartilage tissue engineering constructs. Average quadrupolar couplings were found to be lower in the engineered tissue as compared to the native tissues, presumably due to the lack of order in collagen accumulated in the engineered tissue. These results indicate the use of sodium triple quantum coherence spectroscopy as a tool to investigate anisotropy and growth dynamics of cartilage tissue engineered constructs in a simple and reliable way.

Published
2013

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