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Samouilov A, Komarov D, Petryakov S, Iosilevich A, Zweier JL. Development of an L-band resonator optimized for fast scan EPR imaging of the mouse head. Magn Reson Med 2021; 86:2316-2327. [PMID: 33938574 PMCID: PMC8295191 DOI: 10.1002/mrm.28821] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 04/07/2021] [Accepted: 04/08/2021] [Indexed: 12/11/2022]
Abstract
PURPOSE To develop a novel resonator for high-quality fast scan electron paramagnetic resonance (EPR) and EPR/NMR co-imaging of the head and brain of mice at 1.25 GHz. METHODS Resonator dimensions were scaled to fit the mouse head with maximum filling factor. A single-loop 6-gap resonator of 20 mm diameter and 20 mm length was constructed. High resonator stability was achieved utilizing a fixed position double coupling loop. Symmetrical mutually inverted connections rendered it insensitive to field modulation and fast scan. Coupling adjustment was provided by a parallel-connected variable capacitor located at the feeding line at λ/4 distance. To minimize radiation loss, the shield around the resonator was supplemented with a planar conductive disc that focuses return magnetic flux. RESULTS Coupling of the resonator loaded with the mouse head was efficient and easy. This resonator enabled high-quality in vivo 3D EPR imaging of the mouse head following intravenous infusion of nitroxide probes. With this resonator and rapid scan EPR system, 4 ms scans were acquired in forward and reverse directions so that images with 2-scan 3,136 projections were acquired in 25 s. Head images were achieved with resolutions of 0.4 mm, enabling visualization of probe localization and uptake across the blood-brain barrier. CONCLUSIONS This resonator design provides good sensitivity, high stability, and B1 field homogeneity for in vivo fast scan EPR of the mouse head and brain, enabling faster measurements and higher resolution imaging of probe uptake, localization, and metabolism than previously possible.
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Affiliation(s)
- Alexandre Samouilov
- Davis Heart and Lung Research Institute, and the Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, OH 43210 USA
| | - Denis Komarov
- Davis Heart and Lung Research Institute, and the Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, OH 43210 USA
| | - Sergey Petryakov
- Davis Heart and Lung Research Institute, and the Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, OH 43210 USA
| | - Arkadiy Iosilevich
- Davis Heart and Lung Research Institute, and the Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, OH 43210 USA
| | - Jay L. Zweier
- Davis Heart and Lung Research Institute, and the Division of Cardiovascular Medicine, Department of Internal Medicine, The Ohio State University College of Medicine, Columbus, OH 43210 USA
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Campanella AJ, Nguyen MT, Zhang J, Ngendahimana T, Antholine WE, Eaton GR, Eaton SS, Glezakou VA, Zadrozny JM. Ligand control of low-frequency electron paramagnetic resonance linewidth in Cr(III) complexes. Dalton Trans 2021; 50:5342-5350. [PMID: 33881070 PMCID: PMC8173706 DOI: 10.1039/d1dt00066g] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Understanding how the ligand shell controls low-frequency electron paramagnetic resonance (EPR) spectroscopic properties of metal ions is essential if they are to be used in EPR-based bioimaging schemes. In this work, we probe how specific variations in the ligand structure impact L-band (ca. 1.3 GHz) EPR spectroscopic linewidths in the trichloride salts of five Cr(iii) complexes: [Cr(RR-dphen)3]3+ (RR-dphen = (1R,2R)-(+)-diphenylethylenediamine, 1), [Cr(en)3]3+ (en = ethylenediamine, 2), [Cr(me-en)3]3+ (me-en = 1,2-diaminopropane, 3), [Cr(tn)3]3+ (tn = 1,3-diaminopropane, 4) [Cr(trans-chxn)3]3+ (trans-chxn = trans-(±)-1,2-diaminocyclohexane, 5). Spectral broadening varies in a nonintuitive manner across the series, showing the sharpest peaks for 1 and broadest for 5. Molecular dynamics simulations provide evidence that the broadening is correlated to rigidity in the inner coordination sphere and reflected in ligand-dependent distribution of Cr-N bond distances that can be found in frozen solution.
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Affiliation(s)
- Anthony J Campanella
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA.
| | - Manh-Thuong Nguyen
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, USA
| | - Jun Zhang
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, USA
| | - Thacien Ngendahimana
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA
| | - William E Antholine
- National Biomedical EPR Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Gareth R Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA
| | - Sandra S Eaton
- Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208, USA
| | | | - Joseph M Zadrozny
- Department of Chemistry, Colorado State University, Fort Collins, CO 80523, USA.
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Megow I, Darvin ME, Meinke MC, Lademann J. A Randomized Controlled Trial of Green Tea Beverages on the in vivo Radical Scavenging Activity in Human Skin. Skin Pharmacol Physiol 2017; 30:225-233. [PMID: 28723689 DOI: 10.1159/000477355] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 05/05/2017] [Indexed: 12/22/2022]
Abstract
BACKGROUND Oxidative stress plays an important role in the pathogenesis of various skin diseases. Thus, the antioxidant network of the skin relies on the uptake of exogenous antioxidants to ensure cell protection against radical formation. Green tea is one of the main sources of polyphenolic antioxidant compounds, but only few data are available on its cutaneous antioxidant effects. METHODS The radical scavenging properties of Benifuuki and Yabukita green tea were investigated in the human skin. Thirty-two participants who met the inclusion criteria were randomized to consume 3 cups per day of either Benifuuki tea, Yabukita tea, or water (control group) for 2 weeks. Electron paramagnetic resonance (EPR) spectroscopy was applied to measure the radical scavenging capacity of the skin in vivo before and after the intervention. RESULTS Both Yabukita and Benifuuki tea led to an increase in the radical scavenging activity of the skin by 28 and 29%, respectively, and the difference was significant when compared to the control group. Benifuuki tea, previously reported to be superior in bioavailability due to a highly absorbable methylated catechin, did not prove to be more effective than the common Yabukita tea. CONCLUSION The results show that green tea enhances the radical scavenging capacity of the skin and support the hypothesis that green tea may offer protection against cutaneous oxidative stress.
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Affiliation(s)
- Inna Megow
- Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Center of Experimental and Applied Cutaneous Physiology (CCP), Department of Dermatology, Berlin, Germany
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Haag S, Taskoparan B, Bittl R, Teutloff C, Wenzel R, Fahr A, Chen M, Lademann J, Schäfer-Korting M, Meinke M. Stabilization of Reactive Nitroxides Using Invasomes to Allow Prolonged Electron Paramagnetic Resonance Measurements. Skin Pharmacol Physiol 2011; 24:312-21. [DOI: 10.1159/000330235] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 05/06/2011] [Indexed: 12/23/2022]
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Haag SF, Taskoparan B, Darvin ME, Groth N, Lademann J, Sterry W, Meinke MC. Determination of the antioxidative capacity of the skin in vivo using resonance Raman and electron paramagnetic resonance spectroscopy. Exp Dermatol 2011; 20:483-7. [PMID: 21366704 DOI: 10.1111/j.1600-0625.2010.01246.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Non-invasive measurements are of major interest for investigating the effects of stress, nutrition, diseases or pharmaceuticals on the antioxidative capacity of the human skin. However, only a few non-invasive methods are available. MATERIAL AND METHODS The resonance Raman spectroscopy is well established to monitor carotenoids in the skin, but correlations with other antioxidants have not yet been described. Electron paramagnetic resonance spectroscopy used for measurements of free radicals has already been used elsewhere to investigate the reduction of applied long-living nitroxide radicals, caused by skin antioxidants and UV irradiation, but only a single or up to four volunteers were included in these studies. Therefore, in this study, the two methods were applied in parallel on 17 volunteers, and the rate constant of the nitroxide decrease was correlated with the cutaneous carotenoid concentration. RESULTS AND DISCUSSION A correlation with R = 0.65 was found, supporting the thesis that different antioxidants protect each other and build an antioxidative network in the skin. The results also give first indications that the carotenoids serve as marker substances for the antioxidative capacity, if the nutrition is well balanced.
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Affiliation(s)
- Stefan F Haag
- Department of Biology, Chemistry, and Pharmacy, Freie Universität Berlin, Berlin, Germany
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Zastrow L, Groth N, Klein F, Kockott D, Lademann J, Ferrero L. [UV, visible and infrared light. Which wavelengths produce oxidative stress in human skin?]. Hautarzt 2009; 60:310-7. [PMID: 19319493 DOI: 10.1007/s00105-008-1628-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Experimental evidence suggests that the creation of free radicals--mainly reactive oxygen species (ROS)--is the common photobiological answer to the skin-sunlight interaction. The free radical action spectrum (wavelength dependency) for ultraviolet and visible light (280-700 nm) has been determined by quantitative ESR spectroscopy. Visible light produces around 50% of the total oxidative stress caused by sunlight. Reactive species like *O(-)(2), *OH and *CHR are generated by visible light. The amount of ROS correlates with the visible light intensity (illuminance). We demonstrated the creation of excess free radicals by near-infrared light (NIR, 700-1600 nm). Free radical generation does not depend exclusively on the NIR irradiance, but also on the NIR initiated skin temperature increase. The temperature dependence follows the physiological fever curve. Our results indicate that the complex biological system skin creates the same type of free radicals over the entire active solar spectrum. This general response will make it possible to define the beneficial or deleterious action of sunlight on human skin by introduction of a free radical threshold value.
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Affiliation(s)
- L Zastrow
- Coty/Lancaster SAM, International R&D Center, 2 rue de la Lüjernetta, 98000 Monaco, Monaco.
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Zastrow L, Ferrero L, Herrling T, Groth N. Integrated Sun Protection Factor: A New Sun Protection Factor Based on Free Radicals Generated by UV Irradiation. Skin Pharmacol Physiol 2004; 17:219-31. [PMID: 15452408 DOI: 10.1159/000080215] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2004] [Accepted: 07/20/2004] [Indexed: 11/19/2022]
Abstract
The present work uses the initial step of the whole cascade of biological effects in the skin, the creation of free radicals by means of UVA/UVB radiation, to develop a total sun protection factor. Until now, existing in vivo indices have not been fully satisfying: SPF only reflects protection from UVB light, and persistent pigment darkening is restricted to the UVA part of the sun spectrum. The quantitative measurement of free radicals generated in human skin biopsies by means of electron spin resonance X-band spectroscopy allows to determine a new total SPF. This new sun protection index covers all UVA/UVB wavelengths taking into account their effects in the epidermis as well as the dermis. Use of skin biopsies avoids exposure of human volunteers to potentially harmful radiations. The new index is always practically equal or lower than the in vivo SPF depending on the level of a product's UVA/UVB photoprotection balance. With this, we propose to name this new protection index 'integrated sun protection factor'.
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Affiliation(s)
- L Zastrow
- Coty Beauty/Lancaster Group, International R&D Center, Monaco, Monaco.
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