Mechanisms of Ascorbyl Radical Formation in Human Platelet-Rich Plasma
Identifieur interne : 003C09 ( Pmc/Corpus ); précédent : 003C08; suivant : 003C10Mechanisms of Ascorbyl Radical Formation in Human Platelet-Rich Plasma
Auteurs : Kou-Gi Shyu ; Chao-Chien Chang ; Yu-Chieh Yeh ; Joen-Rong Sheu ; Duen-Suey ChouSource :
- BioMed Research International [ 2314-6133 ] ; 2014.
Abstract
Recently, many clinical reports have suggested that the ascorbyl free radical (Asc∙) can be treated as a noninvasive, reliable, real-time marker of oxidative stress, but its generation mechanisms in human blood have rarely been discussed. In this study, we used upstream substances, enzyme inhibitors, and free radical scavengers to delineate the mechanisms of Asc∙ formation in human platelet-rich plasma (PRP). Our results show that the doublet signal was detected in PRP samples by using electron spin resonance, and the hyperfine splitting of the doublet signal was
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DOI: 10.1155/2014/614506
PubMed: 24696859
PubMed Central: 3947840
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<record><TEI><teiHeader><fileDesc><titleStmt><title xml:lang="en">Mechanisms of Ascorbyl Radical Formation in Human Platelet-Rich Plasma</title><author><name sortKey="Shyu, Kou Gi" sort="Shyu, Kou Gi" uniqKey="Shyu K" first="Kou-Gi" last="Shyu">Kou-Gi Shyu</name><affiliation><nlm:aff id="I1">Division of Cardiology, Shin Kong Wu Ho-Su Memorial Hospital, 95 Wenchang Road, Shihlin Taipei 111, Taiwan</nlm:aff></affiliation><affiliation><nlm:aff id="I2">Graduate Institute of Clinical Medicine, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan</nlm:aff></affiliation></author><author><name sortKey="Chang, Chao Chien" sort="Chang, Chao Chien" uniqKey="Chang C" first="Chao-Chien" last="Chang">Chao-Chien Chang</name><affiliation><nlm:aff id="I3">Department of Cardiology, Cathay General Hospital, 280 Jen Ai Road, Section 4, Taipei 106, Taiwan</nlm:aff></affiliation><affiliation><nlm:aff id="I4">Graduate Institute of Medical Sciences, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan</nlm:aff></affiliation></author><author><name sortKey="Yeh, Yu Chieh" sort="Yeh, Yu Chieh" uniqKey="Yeh Y" first="Yu-Chieh" last="Yeh">Yu-Chieh Yeh</name><affiliation><nlm:aff id="I4">Graduate Institute of Medical Sciences, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan</nlm:aff></affiliation></author><author><name sortKey="Sheu, Joen Rong" sort="Sheu, Joen Rong" uniqKey="Sheu J" first="Joen-Rong" last="Sheu">Joen-Rong Sheu</name><affiliation><nlm:aff id="I4">Graduate Institute of Medical Sciences, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan</nlm:aff></affiliation><affiliation><nlm:aff id="I5">Department of Pharmacology, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan</nlm:aff></affiliation></author><author><name sortKey="Chou, Duen Suey" sort="Chou, Duen Suey" uniqKey="Chou D" first="Duen-Suey" last="Chou">Duen-Suey Chou</name><affiliation><nlm:aff id="I5">Department of Pharmacology, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan</nlm:aff></affiliation></author></titleStmt><publicationStmt><idno type="wicri:source">PMC</idno><idno type="pmid">24696859</idno><idno type="pmc">3947840</idno><idno type="url">http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3947840</idno><idno type="RBID">PMC:3947840</idno><idno type="doi">10.1155/2014/614506</idno><date when="2014">2014</date><idno type="wicri:Area/Pmc/Corpus">003C09</idno><idno type="wicri:explorRef" wicri:stream="Pmc" wicri:step="Corpus" wicri:corpus="PMC">003C09</idno></publicationStmt><sourceDesc><biblStruct><analytic><title xml:lang="en" level="a" type="main">Mechanisms of Ascorbyl Radical Formation in Human Platelet-Rich Plasma</title><author><name sortKey="Shyu, Kou Gi" sort="Shyu, Kou Gi" uniqKey="Shyu K" first="Kou-Gi" last="Shyu">Kou-Gi Shyu</name><affiliation><nlm:aff id="I1">Division of Cardiology, Shin Kong Wu Ho-Su Memorial Hospital, 95 Wenchang Road, Shihlin Taipei 111, Taiwan</nlm:aff></affiliation><affiliation><nlm:aff id="I2">Graduate Institute of Clinical Medicine, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan</nlm:aff></affiliation></author><author><name sortKey="Chang, Chao Chien" sort="Chang, Chao Chien" uniqKey="Chang C" first="Chao-Chien" last="Chang">Chao-Chien Chang</name><affiliation><nlm:aff id="I3">Department of Cardiology, Cathay General Hospital, 280 Jen Ai Road, Section 4, Taipei 106, Taiwan</nlm:aff></affiliation><affiliation><nlm:aff id="I4">Graduate Institute of Medical Sciences, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan</nlm:aff></affiliation></author><author><name sortKey="Yeh, Yu Chieh" sort="Yeh, Yu Chieh" uniqKey="Yeh Y" first="Yu-Chieh" last="Yeh">Yu-Chieh Yeh</name><affiliation><nlm:aff id="I4">Graduate Institute of Medical Sciences, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan</nlm:aff></affiliation></author><author><name sortKey="Sheu, Joen Rong" sort="Sheu, Joen Rong" uniqKey="Sheu J" first="Joen-Rong" last="Sheu">Joen-Rong Sheu</name><affiliation><nlm:aff id="I4">Graduate Institute of Medical Sciences, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan</nlm:aff></affiliation><affiliation><nlm:aff id="I5">Department of Pharmacology, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan</nlm:aff></affiliation></author><author><name sortKey="Chou, Duen Suey" sort="Chou, Duen Suey" uniqKey="Chou D" first="Duen-Suey" last="Chou">Duen-Suey Chou</name><affiliation><nlm:aff id="I5">Department of Pharmacology, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan</nlm:aff></affiliation></author></analytic><series><title level="j">BioMed Research International</title><idno type="ISSN">2314-6133</idno><idno type="eISSN">2314-6141</idno><imprint><date when="2014">2014</date></imprint></series></biblStruct></sourceDesc></fileDesc><profileDesc><textClass></textClass></profileDesc></teiHeader><front><div type="abstract" xml:lang="en"><p>Recently, many clinical reports have suggested that the ascorbyl free radical (Asc<sup>∙</sup>) can be treated as a noninvasive, reliable, real-time marker of oxidative stress, but its generation mechanisms in human blood have rarely been discussed. In this study, we used upstream substances, enzyme inhibitors, and free radical scavengers to delineate the mechanisms of Asc<sup>∙</sup> formation in human platelet-rich plasma (PRP). Our results show that the doublet signal was detected in PRP samples by using electron spin resonance, and the hyperfine splitting of the doublet signal was <italic>a</italic><sup>H</sup> = 1.88 gauss and <italic>g</italic>-factor = 2.00627, which was determined to be the Asc<sup>∙</sup>. We observed that the inhibitors of NADPH oxidase (NOX), cyclooxygenase (COX), lipoxygenase (LOX), cytochrome P450 (CYP450), mitochondria complex III, and nitric oxide synthase (NOS), but not xanthine oxidase, diminished the intensity of the Asc<sup>∙</sup> signal dose dependently. All enzyme inhibitors showed no obvious antioxidant activity during a Fenton reaction assay. In summary, the obtained data suggest that Asc<sup>∙</sup> formation is associated with NOX, COX, LOX, CYP450, eNOS, and mitochondria in human PRP.</p></div></front><back><div1 type="bibliography"><listBibl><biblStruct><analytic><author><name sortKey="Valko, M" uniqKey="Valko M">M Valko</name></author><author><name sortKey="Leibfritz, D" uniqKey="Leibfritz D">D Leibfritz</name></author><author><name sortKey="Moncol, J" uniqKey="Moncol J">J Moncol</name></author><author><name sortKey="Cronin, Mtd" uniqKey="Cronin M">MTD Cronin</name></author><author><name sortKey="Mazur, M" uniqKey="Mazur M">M Mazur</name></author><author><name sortKey="Telser, J" uniqKey="Telser J">J Telser</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Rice Evans, C" uniqKey="Rice Evans C">C Rice-Evans</name></author><author><name sortKey="Miller, N" uniqKey="Miller N">N Miller</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Kokic, An" uniqKey="Kokic A">AN Kokic</name></author><author><name sortKey="Stevic, Z" uniqKey="Stevic Z">Z Stevic</name></author><author><name sortKey="Stojanovic, S" uniqKey="Stojanovic S">S Stojanovic</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Pristov, Jb" uniqKey="Pristov J">JB Pristov</name></author><author><name sortKey="Spasojevic, I" uniqKey="Spasojevic I">I Spasojevic</name></author><author><name sortKey="Mikovic, Z" uniqKey="Mikovic Z">Ž Mikovic</name></author><author><name sortKey="Mandic, V" uniqKey="Mandic V">V Mandic</name></author><author><name sortKey="Cerovic, N" uniqKey="Cerovic N">N Cerovic</name></author><author><name sortKey="Spasic, M" uniqKey="Spasic M">M Spasic</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Slavi, M" uniqKey="Slavi M">M Slavić</name></author><author><name sortKey="Appiah, I" uniqKey="Appiah I">I Appiah</name></author><author><name sortKey="Nikoli Koki, A" uniqKey="Nikoli Koki A">A Nikolić-Kokić</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Townsend, Dm" uniqKey="Townsend D">DM Townsend</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Spasojevi, I" uniqKey="Spasojevi I">I Spasojević</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Buettner, Gr" uniqKey="Buettner G">GR Buettner</name></author><author><name sortKey="Jurkiewicz, Ba" uniqKey="Jurkiewicz B">BA Jurkiewicz</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Buettner, Gr" uniqKey="Buettner G">GR Buettner</name></author><author><name sortKey="Jurkiewicz, Ba" uniqKey="Jurkiewicz B">BA Jurkiewicz</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Chang, Tc" uniqKey="Chang T">TC Chang</name></author><author><name sortKey="Uen, Yh" uniqKey="Uen Y">YH Uen</name></author><author><name sortKey="Chou, Ch" uniqKey="Chou C">CH Chou</name></author><author><name sortKey="Sheu, Jr" uniqKey="Sheu J">JR Sheu</name></author><author><name sortKey="Chou, Ds" uniqKey="Chou D">DS Chou</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Edderkaoui, M" uniqKey="Edderkaoui M">M Edderkaoui</name></author><author><name sortKey="Hong, P" uniqKey="Hong P">P Hong</name></author><author><name sortKey="Vaquero, Ec" uniqKey="Vaquero E">EC Vaquero</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Hsieh, C Y" uniqKey="Hsieh C">C-Y Hsieh</name></author><author><name sortKey="Liu, C L" uniqKey="Liu C">C-L Liu</name></author><author><name sortKey="Hsu, M J" uniqKey="Hsu M">M-J Hsu</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Sakagami, H" uniqKey="Sakagami H">H Sakagami</name></author><author><name sortKey="Satoh, K" uniqKey="Satoh K">K Satoh</name></author><author><name sortKey="Ohata, H" uniqKey="Ohata H">H Ohata</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Vergely, C" uniqKey="Vergely C">C Vergely</name></author><author><name sortKey="Maupoil, V" uniqKey="Maupoil V">V Maupoil</name></author><author><name sortKey="Benderitter, M" uniqKey="Benderitter M">M Benderitter</name></author><author><name sortKey="Rochette, L" uniqKey="Rochette L">L Rochette</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Touyz, Rm" uniqKey="Touyz R">RM Touyz</name></author><author><name sortKey="Schiffrin, El" uniqKey="Schiffrin E">EL Schiffrin</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Hemila, H" uniqKey="Hemila H">H Hemila</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Kim, C" uniqKey="Kim C">C Kim</name></author><author><name sortKey="Dinauer, Mc" uniqKey="Dinauer M">MC Dinauer</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Shiose, A" uniqKey="Shiose A">A Shiose</name></author><author><name sortKey="Sumimoto, H" uniqKey="Sumimoto H">H Sumimoto</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Armstead, Wm" uniqKey="Armstead W">WM Armstead</name></author><author><name sortKey="Mirro, R" uniqKey="Mirro R">R Mirro</name></author><author><name sortKey="Busija, Dw" uniqKey="Busija D">DW Busija</name></author><author><name sortKey="Leffler, Cw" uniqKey="Leffler C">CW Leffler</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Sato, M" uniqKey="Sato M">M Sato</name></author><author><name sortKey="Yokoyama, U" uniqKey="Yokoyama U">U Yokoyama</name></author><author><name sortKey="Fujita, T" uniqKey="Fujita T">T Fujita</name></author><author><name sortKey="Okumura, S" uniqKey="Okumura S">S Okumura</name></author><author><name sortKey="Ishikawa, Y" uniqKey="Ishikawa Y">Y Ishikawa</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Jin, G" uniqKey="Jin G">G Jin</name></author><author><name sortKey="Arai, K" uniqKey="Arai K">K Arai</name></author><author><name sortKey="Murata, Y" uniqKey="Murata Y">Y Murata</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Turrens, Jf" uniqKey="Turrens J">JF Turrens</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Higashi, Y" uniqKey="Higashi Y">Y Higashi</name></author><author><name sortKey="Peng, T" uniqKey="Peng T">T Peng</name></author><author><name sortKey="Du, J" uniqKey="Du J">J Du</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Pallast, S" uniqKey="Pallast S">S Pallast</name></author><author><name sortKey="Arai, K" uniqKey="Arai K">K Arai</name></author><author><name sortKey="Wang, X" uniqKey="Wang X">X Wang</name></author><author><name sortKey="Lo, Eh" uniqKey="Lo E">EH Lo</name></author><author><name sortKey="Van Leyen, K" uniqKey="Van Leyen K">K Van Leyen</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Sch Chinger, V" uniqKey="Sch Chinger V">V Schächinger</name></author><author><name sortKey="Britten, Mb" uniqKey="Britten M">MB Britten</name></author><author><name sortKey="Zeiher, Am" uniqKey="Zeiher A">AM Zeiher</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Munzel, T" uniqKey="Munzel T">T Münzel</name></author><author><name sortKey="Gori, T" uniqKey="Gori T">T Gori</name></author><author><name sortKey="Bruno, Rm" uniqKey="Bruno R">RM Bruno</name></author><author><name sortKey="Taddei, S" uniqKey="Taddei S">S Taddei</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Sies, H" uniqKey="Sies H">H Sies</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Fortu O, A" uniqKey="Fortu O A">A Fortuño</name></author><author><name sortKey="San Jose, G" uniqKey="San Jose G">G San José</name></author><author><name sortKey="Moreno, Mu" uniqKey="Moreno M">MU Moreno</name></author><author><name sortKey="Diez, J" uniqKey="Diez J">J Díez</name></author><author><name sortKey="Zalba, G" uniqKey="Zalba G">G Zalba</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Foster, Ma" uniqKey="Foster M">MA Foster</name></author><author><name sortKey="Pocklington, T" uniqKey="Pocklington T">T Pocklington</name></author><author><name sortKey="Miller, Jdb" uniqKey="Miller J">JDB Miller</name></author><author><name sortKey="Mallard, Jr" uniqKey="Mallard J">JR Mallard</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Cai, H" uniqKey="Cai H">H Cai</name></author><author><name sortKey="Harrison, Dg" uniqKey="Harrison D">DG Harrison</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Munzel, T" uniqKey="Munzel T">T Münzel</name></author><author><name sortKey="Daiber, A" uniqKey="Daiber A">A Daiber</name></author><author><name sortKey="Ullrich, V" uniqKey="Ullrich V">V Ullrich</name></author><author><name sortKey="Mulsch, A" uniqKey="Mulsch A">A Mülsch</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Zweier, Jl" uniqKey="Zweier J">JL Zweier</name></author><author><name sortKey="Talukder, Mah" uniqKey="Talukder M">MAH Talukder</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Munzel, T" uniqKey="Munzel T">T Münzel</name></author><author><name sortKey="Sinning, C" uniqKey="Sinning C">C Sinning</name></author><author><name sortKey="Post, F" uniqKey="Post F">F Post</name></author><author><name sortKey="Warnholtz, A" uniqKey="Warnholtz A">A Warnholtz</name></author><author><name sortKey="Schulz, E" uniqKey="Schulz E">E Schulz</name></author></analytic></biblStruct><biblStruct><analytic><author><name sortKey="Radomski, Mw" uniqKey="Radomski M">MW Radomski</name></author><author><name sortKey="Palmer, Rmj" uniqKey="Palmer R">RMJ Palmer</name></author><author><name sortKey="Moncada, S" uniqKey="Moncada S">S Moncada</name></author></analytic></biblStruct></listBibl></div1></back></TEI><pmc article-type="research-article"><pmc-dir>properties open_access</pmc-dir>
<front><journal-meta><journal-id journal-id-type="nlm-ta">Biomed Res Int</journal-id><journal-id journal-id-type="iso-abbrev">Biomed Res Int</journal-id><journal-id journal-id-type="publisher-id">BMRI</journal-id><journal-title-group><journal-title>BioMed Research International</journal-title></journal-title-group><issn pub-type="ppub">2314-6133</issn><issn pub-type="epub">2314-6141</issn><publisher><publisher-name>Hindawi Publishing Corporation</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="pmid">24696859</article-id><article-id pub-id-type="pmc">3947840</article-id><article-id pub-id-type="doi">10.1155/2014/614506</article-id><article-categories><subj-group subj-group-type="heading"><subject>Research Article</subject></subj-group></article-categories><title-group><article-title>Mechanisms of Ascorbyl Radical Formation in Human Platelet-Rich Plasma</article-title></title-group><contrib-group><contrib contrib-type="author"><name><surname>Shyu</surname><given-names>Kou-Gi</given-names></name><xref ref-type="aff" rid="I1"><sup>1</sup></xref><xref ref-type="aff" rid="I2"><sup>2</sup></xref></contrib><contrib contrib-type="author"><name><surname>Chang</surname><given-names>Chao-Chien</given-names></name><xref ref-type="aff" rid="I3"><sup>3</sup></xref><xref ref-type="aff" rid="I4"><sup>4</sup></xref></contrib><contrib contrib-type="author"><name><surname>Yeh</surname><given-names>Yu-Chieh</given-names></name><xref ref-type="aff" rid="I4"><sup>4</sup></xref></contrib><contrib contrib-type="author"><name><surname>Sheu</surname><given-names>Joen-Rong</given-names></name><xref ref-type="aff" rid="I4"><sup>4</sup></xref><xref ref-type="aff" rid="I5"><sup>5</sup></xref><xref ref-type="corresp" rid="cor1">*</xref></contrib><contrib contrib-type="author"><contrib-id contrib-id-type="orcid" authenticated="false">http://orcid.org/0000-0002-1653-992X</contrib-id><name><surname>Chou</surname><given-names>Duen-Suey</given-names></name><xref ref-type="aff" rid="I5"><sup>5</sup></xref><xref ref-type="corresp" rid="cor2">*</xref></contrib></contrib-group><aff id="I1"><sup>1</sup>Division of Cardiology, Shin Kong Wu Ho-Su Memorial Hospital, 95 Wenchang Road, Shihlin Taipei 111, Taiwan</aff><aff id="I2"><sup>2</sup>Graduate Institute of Clinical Medicine, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan</aff><aff id="I3"><sup>3</sup>Department of Cardiology, Cathay General Hospital, 280 Jen Ai Road, Section 4, Taipei 106, Taiwan</aff><aff id="I4"><sup>4</sup>Graduate Institute of Medical Sciences, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan</aff><aff id="I5"><sup>5</sup>Department of Pharmacology, Taipei Medical University, 250 Wu-Hsing Street, Taipei 110, Taiwan</aff><author-notes><corresp id="cor1">*Joen-Rong Sheu: <email>sheujr@tmu.edu.tw</email> and </corresp><corresp id="cor2">*Duen-Suey Chou: <email>fird@tmu.edu.tw</email></corresp><fn fn-type="other"><p>Academic Editor: Philip Aloysius Thomas</p></fn></author-notes><pub-date pub-type="ppub"><year>2014</year></pub-date><pub-date pub-type="epub"><day>17</day><month>2</month><year>2014</year></pub-date><volume>2014</volume><elocation-id>614506</elocation-id><history><date date-type="received"><day>21</day><month>11</month><year>2013</year></date><date date-type="accepted"><day>9</day><month>1</month><year>2014</year></date></history><permissions><copyright-statement>Copyright © 2014 Kou-Gi Shyu et al.</copyright-statement><copyright-year>2014</copyright-year><license xlink:href="https://creativecommons.org/licenses/by/3.0/"><license-p>This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.</license-p></license></permissions><abstract><p>Recently, many clinical reports have suggested that the ascorbyl free radical (Asc<sup>∙</sup>) can be treated as a noninvasive, reliable, real-time marker of oxidative stress, but its generation mechanisms in human blood have rarely been discussed. In this study, we used upstream substances, enzyme inhibitors, and free radical scavengers to delineate the mechanisms of Asc<sup>∙</sup> formation in human platelet-rich plasma (PRP). Our results show that the doublet signal was detected in PRP samples by using electron spin resonance, and the hyperfine splitting of the doublet signal was <italic>a</italic><sup>H</sup> = 1.88 gauss and <italic>g</italic>-factor = 2.00627, which was determined to be the Asc<sup>∙</sup>. We observed that the inhibitors of NADPH oxidase (NOX), cyclooxygenase (COX), lipoxygenase (LOX), cytochrome P450 (CYP450), mitochondria complex III, and nitric oxide synthase (NOS), but not xanthine oxidase, diminished the intensity of the Asc<sup>∙</sup> signal dose dependently. All enzyme inhibitors showed no obvious antioxidant activity during a Fenton reaction assay. In summary, the obtained data suggest that Asc<sup>∙</sup> formation is associated with NOX, COX, LOX, CYP450, eNOS, and mitochondria in human PRP.</p></abstract><funding-group><award-group><funding-source>http://dx.doi.org/10.13039/501100001868 National Science Council Taiwan</funding-source><award-id>NSC97-2320-B-038-016-MY3</award-id></award-group><award-group><funding-source>http://dx.doi.org/10.13039/501100001868 National Science Council Taiwan</funding-source><award-id>NSC100-2320-B-038-021-MY3</award-id></award-group></funding-group></article-meta></front><body><sec id="sec1"><title>1. Introduction</title><p>Interest in treating oxidative stress has grown in medicine over the past 2 decades. The oxidative status of a biosystem represents a relative level of oxidation in living organisms and is crucial for understanding numerous human physiological and pathophysiological processes [<xref rid="B1" ref-type="bibr">1</xref>]. Overproduction of ROS results in oxidative stress, a pathophysiological process that can damage cell structures and induce cancer, cardiovascular disease, atherosclerosis, hypertension, diabetes mellitus, neurodegenerative diseases, rheumatoid arthritis, and ageing. In contrast, ROS play a physiological role in protection against infectious organisms, in the function of several cellular signalling pathways, and the generation of a mitogenic response at low/moderate concentrations [<xref rid="B1" ref-type="bibr">1</xref>]. Oxidative status can be estimated using biochemical assays, such as the 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) assay [<xref rid="B2" ref-type="bibr">2</xref>], and by measuring the activity of superoxide dismutating enzymes (Mn superoxide dismutase (SOD) and CuZnSOD), catalase (CAT), GSH peroxidase, and reductase [<xref rid="B3" ref-type="bibr">3</xref>–<xref rid="B5" ref-type="bibr">5</xref>], as well as the level of S-glutathionylation [<xref rid="B6" ref-type="bibr">6</xref>]. However, Spasojević suggested that these techniques be supplemented by electron spin resonance (ESR) spectroscopy to enable acquiring data on oxidative status that are more specific [<xref rid="B7" ref-type="bibr">7</xref>]. Certain endogenous paramagnetic molecules, such as the ascorbyl free radical (Asc<sup>∙</sup>), tocopheryl radical, and melanin radical, are biomarkers of oxidative status that can be detected using ESR spectroscopy [<xref rid="B7" ref-type="bibr">7</xref>].</p><p>Ascorbic acid is an essential biological component that can be oxidized through a two-step oxidation process involving a free radical intermediate; this oxidation process may be performed by nearly all oxidizing species intrinsic to the biological environment [<xref rid="B7" ref-type="bibr">7</xref>]. When using ESR spectroscopy, the concentration of the Asc<sup>∙</sup> can be measured using a lower limit of approximately 5 nM with a standard deviation of <1 nM [<xref rid="B8" ref-type="bibr">8</xref>]. The characteristics of the Asc<sup>∙</sup> are relatively stable and it has a long half-life, indicating that it is the most useful biomarker of oxidative status in living systems [<xref rid="B7" ref-type="bibr">7</xref>].</p><p>ESR spectroscopy was first applied in detecting the Asc<sup>∙</sup> in oxidative status research in 1993 [<xref rid="B9" ref-type="bibr">9</xref>]. Thus far, the Asc<sup>∙</sup> has been treated as a noninvasive, reliable, real-time biomarker of oxidative stress in various biological samples including plasma, serum, whole blood, cerebrospinal fluid, extracellular fluid, synovial fluid, seminal fluid, tumor, and heart tissue samples [<xref rid="B7" ref-type="bibr">7</xref>]; however, the generation mechanisms of the Asc<sup>∙</sup> in human blood have rarely been discussed.</p><p>Ascorbate (the reduced form of vitamin C) is an important radical scavenger and antioxidant in human plasma. Asc<sup>∙</sup> has been detected by ESR in various biological samples including plasma, serum, whole blood, cerebrospinal fluid, skin, extracellular fluid, synovial fluid, gastric mucosa, seminal fluid, tumors, heart tissue, and others [<xref rid="B7" ref-type="bibr">7</xref>]. We recently applied ESR spectroscopy in detecting the Asc<sup>∙</sup> to investigate the mechanisms of oxidative stress caused by lymphedema in mice [<xref rid="B10" ref-type="bibr">10</xref>]. In this study, we used upstream substances, enzyme inhibitors, and free radical scavengers to delineate the mechanisms of Asc<sup>∙</sup> formation in human platelet-rich plasma (PRP).</p></sec><sec id="sec2"><title>2. Materials and Methods</title><sec id="sec2.1"><title>2.1. Materials</title><p>AA861, allopurinol, antimycin, arachidonic acid (AA), baicalein, CAT, clotrimazole, dimethyl sulfoxide (DMSO), diphenyleneiodonium (DPI), ethylenediaminetetraacetic acid, hemoglobin, indomethacin, NG-nitro-L-arginine methyl ester (L-NAME), quinacrine, and SOD were purchased from Sigma Chemical (St. Louis, MO, USA). L(+)-ascorbic acid was purchased from Wako Pure Chemical Industries (Osaka, Japan).</p></sec><sec id="sec2.2"><title>2.2. Human Blood Collection Procedure</title><p>This study was approved by the Institutional Review Board of Taipei Medical University and conformed to the principles outlined in the Helsinki Declaration. All human volunteers provided informed consent to participate.</p></sec><sec id="sec2.3"><title>2.3. Preparation of Human Blood Components</title><p>Whole blood was collected from healthy human volunteers who had taken no medicine during the preceding 2 wk and was mixed with acid/citrate/glucose. After centrifugation at 120 ×g for 10 min at room temperature, the supernatant (PRP) was supplemented with PGE<sub>1</sub> (0.5 <italic>μ</italic>M) and heparin (6.4 IU/mL) and then incubated for 10 min at 30°C and centrifuged at 500 ×g for 10 min. The supernatant was platelet-poor plasma (PPP) and was used in subsequent experiments.</p></sec><sec id="sec2.4"><title>2.4. Isolation of Red Blood Cells</title><p>Whole blood was centrifuged at 650 ×g for 5 min. Plasma was removed carefully and the white buffy layer was completely removed through aspiration using a pipette with utmost care. The red blood cells (RBCs) were then washed three additional times with Tyrode's solution.</p></sec><sec id="sec2.5"><title>2.5. Measurement of the Ascorbyl Free Radical in Platelet-Rich Plasma Using Electron Paramagnetic Resonance Spectrometry</title><p>The ESR method involved using a Bruker EMX ESR spectrometer (Bruker Instruments Inc., Billerica, MA, USA) as described previously [<xref rid="B14" ref-type="bibr">11</xref>]. The PRP was prewarmed to 37°C for 2 min, and enzyme inhibitors or other reagents were then added. ESR spectra were recorded at room temperature by using a quartz flat cell designed for aqueous solutions. ESR spectrometry was conducted under the following conditions: 20 mW of power at 9.78 GHz, with a scan range of 100 G and a receiver gain of 5 × 10<sup>4</sup>. The modulation amplitude, sweep time, and time constant are provided in the figure legends.</p></sec><sec id="sec2.6"><title>2.6. Fenton Reaction Model System with Electron Paramagnetic Resonance Detection of the Hydroxyl Radical</title><p>The hydroxyl radical generated in a standard Fenton reaction was trapped using DMPO according to the method previously described [<xref rid="B11" ref-type="bibr">12</xref>]. A Fenton reaction solution (50 <italic>μ</italic>M FeSO<sub>4</sub> + 500 <italic>μ</italic>M H<sub>2</sub>O<sub>2</sub>) was pretreated with a solvent control (0.6% DMSO) or reagent (10 <italic>μ</italic>M). The ESR spectra were recorded after precisely 3 min.</p></sec><sec id="sec2.7"><title>2.7. Statistical Analysis</title><p>The experimental results are expressed as the mean ± SEM and are accompanied by the number (<italic>n</italic>) of observations. The data were assessed using an analysis of variance (ANOVA). When this analysis indicated significant differences among the group means, each group was compared using the Newman-Keuls method. A <italic>P</italic> value <0.05 was considered statistically significant.</p></sec></sec><sec id="sec3"><title>3. Results</title><sec id="sec3.1"><title>3.1. Electron Spin Resonance Investigations of Free Radicals Formed in Human Blood Components</title><p>Free radical signals were detected using ESR in human PPP, PRP, RBCs, and whole blood. A doublet signal radical was observed in PPP and PRP, but not in RBCs or whole blood (<xref ref-type="fig" rid="fig1">Figure 1(a)</xref>). PRP exhibited the strongest signal among the human blood components and was used in subsequent experiments. The hyperfine splitting and <italic>g</italic>-factor of this doublet signal were 1.88 G and 2.00627, respectively. In each instance, the signals exhibited doublet peaks and a line width of approximately 4 G. The radical species was identified to be ascorbyl based on the close similarity of the hyperfine coupling constants and <italic>g</italic>-factor of the observed signal to those of published data [<xref rid="B12" ref-type="bibr">13</xref>, <xref rid="B13" ref-type="bibr">14</xref>]. No notable oxygen-derived free radicals were detected in this study, probably because of the presence of ascorbic acid and other antioxidants in human PRP.</p></sec><sec id="sec3.2"><title>3.2. Effect of Exogenous Ascorbic Acid on the <italic>g</italic> = 2.00627 Radical Formation in Human Platelet-Rich Plasma</title><p>To confirm that the <italic>g</italic> = 2.00627 radical was a typical Asc<sup>∙</sup>, we added exogenous ascorbic acid to human PRP. The intensity of the <italic>g</italic> = 2.00627 radical induced by exogenous ascorbic acid increased dose dependently (<xref ref-type="fig" rid="fig1">Figure 1(b)</xref>).</p></sec><sec id="sec3.3"><title>3.3. Effect of Superoxide and the Nitric Oxide Scavenger on Ascorbyl Free Radical Formation in Human Platelet-Rich Plasma</title><p>We propose that the Asc<sup>∙</sup> is a secondary radical; therefore, we determined which types of primary radical may be involved in the formation of this radical species. The effects of superoxide and the nitric oxide scavenger were examined on the <italic>g</italic> = 2.00627 radical formation, as shown in <xref ref-type="fig" rid="fig2">Figure 2</xref>. The <italic>g</italic> = 2.00627 signal formed by PRP was arbitrarily designated 100% and was inhibited by the superoxide scavenger (120 U/mL of SOD and 1000 U/mL of CAT) and nitric oxide scavenger (1 <italic>μ</italic>g/mL of hemoglobin) to 26.1% (<italic>P</italic> < 0.01) and 13.5% (<italic>P</italic> < 0.05), respectively. This result indicates that superoxide and nitric oxide may be primary radicals that induce Asc<sup>∙</sup> formation.</p></sec><sec id="sec3.4"><title>3.4. Effect of the NADPH Oxidase Inhibitor on Ascorbyl Free Radical Formation in Human Platelet-Rich Plasma</title><p>It was reported that NOX on the cell membrane of leucocytes may be the primary source of superoxide formation in blood [<xref rid="B30" ref-type="bibr">15</xref>]. To investigate the involvement of NOX in Asc<sup>∙</sup> formation in PRP, we used DPI as a NOX nonselective inhibitor. The Asc<sup>∙</sup> signal of a solvent control group was arbitrarily designated 100% and was dose dependently inhibited by DPI (3 <italic>μ</italic>M = 17.7%, <italic>P</italic> < 0.05; 10 <italic>μ</italic>M = 23.8%, <italic>P</italic> < 0.001, <xref ref-type="fig" rid="fig3">Figure 3(a)</xref>). This result indicates that NOX may be involved in the formation of Asc<sup>∙</sup> in PRP.</p></sec><sec id="sec3.5"><title>3.5. Effect of the Xanthine Oxidase Inhibitor on Ascorbyl Free Radical Formation in Human Platelet-Rich Plasma</title><p>XO is a superoxide-producing enzyme normally present in the serum and lungs [<xref rid="B20" ref-type="bibr">16</xref>]. To investigate the involvement of XO in Asc<sup>∙</sup> formation in PRP, we used allopurinol as a nonselective XO inhibitor. The Asc<sup>∙</sup> signal of a solvent control group was arbitrarily designated 100%, and allopurinol (1–10 <italic>μ</italic>M) did not significantly influence Asc<sup>∙</sup> formation in PRP (<italic>P</italic> > 0.05, <xref ref-type="fig" rid="fig3">Figure 3(b)</xref>).</p></sec><sec id="sec3.6"><title>3.6. Effect of the Nitric Oxide Synthase Inhibitor on Ascorbyl Free Radical Formation in Human Platelet-Rich Plasma</title><p>We determined whether NOS is involved in Asc<sup>∙</sup> formation in PRP. We used L-NAME as an NOS inhibitor. The Asc<sup>∙</sup> signal of a solvent control group was arbitrarily designated 100% and was inhibited by L-NAME (1–10 <italic>μ</italic>M) dose dependently (3 <italic>μ</italic>M = 18.6%, <italic>P</italic> < 0.05; 10 <italic>μ</italic>M = 25.4%, <italic>P</italic> < 0.01, <xref ref-type="fig" rid="fig3">Figure 3(c)</xref>). This result indicates that NOS-derived NO is associated with the formation of Asc<sup>∙</sup> in PRP.</p></sec><sec id="sec3.7"><title>3.7. Effect of Arachidonic Acid on Ascorbyl Free Radical Formation in Human Platelet-Rich Plasma</title><p>Reactive oxygen species (ROS) are generated by AA metabolites, which are released from the cell membrane. AA-induced ROS generation may occur through the oxidative metabolic processes induced by COX and LOX [<xref rid="B14" ref-type="bibr">11</xref>]. AA has also been reported to induce ROS formation through NOX [<xref rid="B15" ref-type="bibr">17</xref>, <xref rid="B16" ref-type="bibr">18</xref>]. Our results showed that NOX may be involved in the formation of the Asc<sup>∙</sup> in PRP (<xref ref-type="fig" rid="fig3">Figure 3(a)</xref>). Therefore, we determined whether AA metabolite pathways are associated with the Asc<sup>∙</sup> formation. The Asc<sup>∙</sup> signal formed by PRP was, respectively, increased 39.1% (<italic>P</italic> < 0.05) and 62.4% (<italic>P</italic> < 0.001) by 10 <italic>μ</italic>M and 100 <italic>μ</italic>M AA compared with a solvent control (<xref ref-type="fig" rid="fig4">Figure 4(a)</xref>). In addition, the Asc<sup>∙</sup> signal of the solvent control group was arbitrarily designated 100% and was inhibited by quinacrine (2.5–10 <italic>μ</italic>M), a phospholipidase A<sub>2</sub> (PLA<sub>2</sub>) inhibitor, dose dependently (5 <italic>μ</italic>M = 20.9%, <italic>P</italic> < 0.001; 10 <italic>μ</italic>M = 26.2%, <italic>P</italic> < 0.001, <xref ref-type="fig" rid="fig4">Figure 4(b)</xref>). This result indicates that AA metabolite pathways are associated with the formation of the Asc<sup>∙</sup> in PRP.</p></sec><sec id="sec3.8"><title>3.8. Effect of the Cyclooxygenase Inhibitor on Ascorbyl Free Radical Formation in Human Platelet-Rich Plasma</title><p>In downstream pathways of the AA metabolism, COX [<xref rid="B17" ref-type="bibr">19</xref>], P450 [<xref rid="B18" ref-type="bibr">20</xref>], and LOX [<xref rid="B19" ref-type="bibr">21</xref>] are vital sources of extracellular ROS release. To investigate the involvement of COX in Asc<sup>∙</sup> formation in PRP, we used indomethacin as a nonselective COX inhibitor. The Asc<sup>∙</sup> signal of a solvent control group was arbitrarily designated 100%; 3 and 10 <italic>μ</italic>M indomethacin produced a 13.4% (<italic>P</italic> < 0.05) and 14.5% (<italic>P</italic> < 0.01) reduction of the Asc<sup>∙</sup> signal, respectively. However, the signal was not significantly changed when a low dose (1 <italic>μ</italic>M) of indomethacin (<xref ref-type="fig" rid="fig5">Figure 5(a)</xref>) was used. This result suggests that COX may be involved in the formation of the Asc<sup>∙</sup> in PRP.</p></sec><sec id="sec3.9"><title>3.9. Effect of the Lipoxygenase Inhibitor on Ascorbyl Free Radical Formation in Human Platelet-Rich Plasma</title><p>To investigate the involvement of LOX in Asc<sup>∙</sup> formation in PRP, we used AA861 as a nonselective LOX inhibitor. The Asc<sup>∙</sup> signal of a solvent control group was arbitrarily designated 100% and was inhibited by AA861 (1–10 <italic>μ</italic>M) dose dependently (10 <italic>μ</italic>M = 25.7%, <italic>P</italic> < 0.001, <xref ref-type="fig" rid="fig5">Figure 5(b)</xref>). This result suggests that LOX may also be involved in the formation of Asc<sup>∙</sup> in PRP.</p></sec><sec id="sec3.10"><title>3.10. Effect of the P450 Inhibitor on Ascorbyl Free Radical Formation in Human Platelet-Rich Plasma</title><p>To investigate the involvement of P450 in Asc<sup>∙</sup> formation in PRP, we used clotrimazole as a nonselective P450 inhibitor. As shown in <xref ref-type="fig" rid="fig5">Figure 5(c)</xref>, 1 and 10 <italic>μ</italic>M clotrimazole produced 13.7% (<italic>P</italic> < 0.01) and 19.5% (<italic>P</italic> < 0.01) depressions of the Asc<sup>∙</sup> signal, respectively.</p></sec><sec id="sec3.11"><title>3.11. Influence of the Mitochondrial Respiratory Chain on Ascorbyl Free Radical Formation in Human Platelet-Rich Plasma</title><p>In the mitochondrial respiratory chain, some electrons may leak to oxygen, partially reducing oxygen to a superoxide anion [<xref rid="B21" ref-type="bibr">22</xref>]. We determined whether oxidative stress induced by the mitochondrial respiratory chain is associated with Asc<sup>∙</sup> formation in PRP. We used antimycin as a mitochondrial complex III inhibitor. The Asc<sup>∙</sup> signal of a solvent control group was arbitrarily designated 100%, and 10, 30, and 100 <italic>μ</italic>M antimycin, respectively, produced 19.2% (<italic>P</italic> < 0.001), 23.3% (<italic>P</italic> < 0.001), and 32.5% (<italic>P</italic> < 0.001) depressions of the Asc<sup>∙</sup> signal (<xref ref-type="fig" rid="fig6">Figure 6</xref>). This indicates that mitochondrial respiratory chain oxidative stress plays a partial role in Asc<sup>∙</sup> formation in PRP.</p></sec><sec id="sec3.12"><title>3.12. Antioxidative Assay of Enzyme Inhibitors</title><p>Higashi et al. demonstrated that nordihydroguaiaretic acid, AA-861, and baicalein are LOX inhibitors and also have antioxidant activity [<xref rid="B33" ref-type="bibr">23</xref>]. However, Pallast et al. showed that AA-861 inhibits both 12/15-LOX and 5-LOX but does not have antioxidant activity [<xref rid="B34" ref-type="bibr">24</xref>]. Therefore, we selected AA-861 as a LOX inhibitor in this study. However, some enzyme inhibitors used in this study still potentially elicit antioxidative effects and inhibit Asc<sup>∙</sup> signal production. To exclude this possibility, we used the Fenton reaction assay to determine whether the enzyme inhibitors were also antioxidants. The enzyme inhibitors were divided into lipid-soluble (<xref ref-type="fig" rid="fig7">Figure 7(a)</xref>) and water-soluble (<xref ref-type="fig" rid="fig7">Figure 7(b)</xref>) groups. Our result showed that DPI (10 <italic>μ</italic>M), AA861 (10 <italic>μ</italic>M), L-NAME (10 <italic>μ</italic>M), allopurinol (10 <italic>μ</italic>M), clotrimazole (10 <italic>μ</italic>M), indomethacin (10 <italic>μ</italic>M), quinacrine (10 <italic>μ</italic>M), and antimycin (10 <italic>μ</italic>M) did not exhibit significant antioxidative activity in the Fenton reaction assay (<italic>P</italic> > 0.05).</p></sec></sec><sec id="sec4"><title>4. Discussion</title><p>The vascular endothelium plays an essential role in regulating vascular tone, modulating vascular growth, platelet aggregation and coagulation, and inflammation. Therefore, the degree of endothelial dysfunction may predict the outcomes of cardiovascular diseases [<xref rid="B22" ref-type="bibr">25</xref>]. Although the precise mechanisms of endothelial dysfunction have not been elucidated, a considerable amount of evidence suggests that increased oxidative stress may play a critical role in this state [<xref rid="B23" ref-type="bibr">26</xref>]. Oxidative stress can be described as an “imbalance between proxidants and antioxidants in favor of the proxidants, potentially leading to damage” [<xref rid="B24" ref-type="bibr">27</xref>]. Currently, reducing oxidative stress remains a prominent objective for cardiovascular prevention and therapy. However, clear knowledge of its source is required to provide novel perspectives for treatment.</p><p>ROS participate in the growth, apoptosis, and migration of vascular smooth muscle cells and in the remodeling of the vessel wall. Each of these responses may contribute to vascular diseases in uncontrolled conditions [<xref rid="B25" ref-type="bibr">28</xref>]. Therefore, the sources of ROS may be crucial therapeutic targets of cardiovascular disease.</p><p>In this study, we found that Asc<sup>∙</sup> signals were observed in PPP and PRP, but not in RBCs or whole blood (<xref ref-type="fig" rid="fig1">Figure 1(a)</xref>). A study of ESR spectra of whole blood from normal and tumour bearing patients showed two main lines with <italic>g</italic> values of 4.2 and 2.049 [<xref rid="B32" ref-type="bibr">29</xref>]. The authors suggested that the line at <italic>g</italic> = 2.049 may be due to the copper protein ceruloplasmin. In addition, smaller signals were found with <italic>g</italic> values of 2.16, 2.005, and 1.98. We suggest that some paramagnetic species in whole blood with <italic>g</italic> values nearby 2.0 that restrict the signal intensity of ascorbyl radical. Therefore, in this study, we used ESR spectroscopy in detecting the Asc<sup>∙</sup> to determine the sources of oxidative stress in human PRP. Asc<sup>∙</sup> formation may be induced by nearly all ROS intrinsic to the biological environment, including superoxide radicals, hydroxyl radicals, alkyl peroxyl radicals, lipid peroxyl radicals, peroxynitrite, thiyl radicals, protein radicals, and catalytic metals [<xref rid="B7" ref-type="bibr">7</xref>].</p><p>In the vasculature wall, ROS are produced by all of the layers, and the major vascular ROS is the superoxide anion, which inactivates NO and, thus, impairs relaxation [<xref rid="B26" ref-type="bibr">30</xref>]. Superoxide-generating enzymes involved in increased oxidative stress within vascular tissue include uncoupled NOS, NOX, XO, and mitochondrial superoxide-generating enzymes [<xref rid="B27" ref-type="bibr">31</xref>]. In this study, we observed that the AA pathway enzymes, such as COX, LOX, and CYP450, also contributed to the increased oxidative stress in human PRP. However, the XO did not seem to play an important role in this event (<xref ref-type="fig" rid="fig8">Figure 8</xref>).</p><p>XO is capable of generating superoxide and hydrogen peroxide when supplied with its substrates, xanthine and hypoxanthine, which accumulate during ischemia [<xref rid="B28" ref-type="bibr">32</xref>]. Although studies have shown that XO is present in human arterial and venous endothelial cells and can generate sufficient levels of oxygen radicals to trigger endothelial injury, questions remain regarding the role of xanthine and hypoxanthine formation in triggering this process. Because the samples in this study were not subjected to ischemic conditions, we did not observe XO contributing to oxidative stress in human PRP.</p><p>NO is released from endothelial cells mainly by eNOS and is a main mediator of endothelium-dependent vasodilatation. When ROS production is increased, tetrahydrobiopterin generation is reduced, causing eNOS to uncouple and produce superoxide; when NO is insufficiently formed or quenched too quickly, the process of atherosclerosis is initiated or accelerated [<xref rid="B29" ref-type="bibr">33</xref>]. In pathological conditions, NO may be scavenged by excess ROS generated in blood vessels by vascular NOX [<xref rid="B30" ref-type="bibr">15</xref>]. eNOS has been observed not only in the endothelium but also in platelets [<xref rid="B31" ref-type="bibr">34</xref>]. Therefore, based on our results, we suggest that platelet eNOS is also a source of ROS in human PRP.</p><p>We recently applied ESR spectroscopy in detecting Asc<sup>∙</sup> to investigate the oxidative status of lymphedema, suggesting that COX-derived oxidative stress plays a major role in the pathological mechanisms of surgically induced lymphedema [<xref rid="B10" ref-type="bibr">10</xref>]. However, in the current study, COX-derived oxidative stress played only a minor role in oxidative stress in human PRP.</p></sec><sec id="sec5"><title>5. Conclusion</title><p>In this study, we investigated the potential sources of Asc<sup>∙</sup> production that contribute to oxidative stress in human PRP. We provide evidence that no single source of Asc<sup>∙</sup> can be identified in human PRP, but Asc<sup>∙</sup> are typically generated through NOX, COX, LOX, CYP450, eNOS, and mitochondrial superoxide-generating enzyme pathways.</p></sec></body><back><ack><title>Acknowledgments</title><p>This work was supported by Grants from the National Science Council of Taiwan (NSC97-2320-B-038-016-MY3 and NSC100-2320-B-038-021-MY3) and Shin Kong Wu Ho-Su Memorial Hospital-Taipei Medical University (SKH-TMU-100-12).</p></ack><sec sec-type="conflict"><title>Conflict of Interests</title><p>The authors declare that there is no conflict of interests regarding the publication of this paper.</p></sec><ref-list><ref id="B1"><label>1</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Valko</surname><given-names>M</given-names></name><name><surname>Leibfritz</surname><given-names>D</given-names></name><name><surname>Moncol</surname><given-names>J</given-names></name><name><surname>Cronin</surname><given-names>MTD</given-names></name><name><surname>Mazur</surname><given-names>M</given-names></name><name><surname>Telser</surname><given-names>J</given-names></name></person-group><article-title>Free radicals and antioxidants in normal physiological functions and human disease</article-title><source><italic>International Journal of Biochemistry and Cell Biology</italic></source><year>2007</year><volume>39</volume><issue>1</issue><fpage>44</fpage><lpage>84</lpage><pub-id pub-id-type="other">2-s2.0-33749986298</pub-id><pub-id pub-id-type="pmid">16978905</pub-id></element-citation></ref><ref id="B2"><label>2</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Rice-Evans</surname><given-names>C</given-names></name><name><surname>Miller</surname><given-names>N</given-names></name></person-group><article-title>Measurement of the antioxidant status of dietary constituents, low density lipoproteins and plasma</article-title><source><italic>Prostaglandins Leukotrienes and Essential Fatty Acids</italic></source><year>1997</year><volume>57</volume><issue>4-5</issue><fpage>499</fpage><lpage>505</lpage><pub-id pub-id-type="other">2-s2.0-0030734963</pub-id></element-citation></ref><ref id="B3"><label>3</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Kokic</surname><given-names>AN</given-names></name><name><surname>Stevic</surname><given-names>Z</given-names></name><name><surname>Stojanovic</surname><given-names>S</given-names></name><etal></etal></person-group><article-title>Biotransformation of nitric oxide in the cerebrospinal fluid of amyotrophic lateral sclerosis patients</article-title><source><italic>Redox Report</italic></source><year>2005</year><volume>10</volume><issue>5</issue><fpage>265</fpage><lpage>270</lpage><pub-id pub-id-type="pmid">16354415</pub-id></element-citation></ref><ref id="B4"><label>4</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Pristov</surname><given-names>JB</given-names></name><name><surname>Spasojevic</surname><given-names>I</given-names></name><name><surname>Mikovic</surname><given-names>Ž</given-names></name><name><surname>Mandic</surname><given-names>V</given-names></name><name><surname>Cerovic</surname><given-names>N</given-names></name><name><surname>Spasic</surname><given-names>M</given-names></name></person-group><article-title>Antioxidative defense enzymes in placenta protect placenta and fetus in inherited thrombophilia from hydrogen peroxide</article-title><source><italic>Oxidative Medicine and Cellular Longevity</italic></source><year>2009</year><volume>2</volume><issue>1</issue><fpage>14</fpage><lpage>18</lpage><pub-id pub-id-type="other">2-s2.0-77953283808</pub-id><pub-id pub-id-type="pmid">20046640</pub-id></element-citation></ref><ref id="B5"><label>5</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Slavić</surname><given-names>M</given-names></name><name><surname>Appiah</surname><given-names>I</given-names></name><name><surname>Nikolić-Kokić</surname><given-names>A</given-names></name><etal></etal></person-group><article-title>The anti-oxidative defence system in the isolated rat uterus during spontaneous rhythmic activity</article-title><source><italic>Acta Physiologica Hungarica</italic></source><year>2006</year><volume>93</volume><issue>4</issue><fpage>335</fpage><lpage>339</lpage><pub-id pub-id-type="other">2-s2.0-33845882797</pub-id><pub-id pub-id-type="pmid">17191665</pub-id></element-citation></ref><ref id="B6"><label>6</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Townsend</surname><given-names>DM</given-names></name></person-group><article-title>S-glutathionylation: indicator of cell stress and regulator of the unfolded protein response</article-title><source><italic>Molecular Interventions</italic></source><year>2008</year><volume>7</volume><issue>6</issue><fpage>313</fpage><lpage>324</lpage><pub-id pub-id-type="other">2-s2.0-38349049487</pub-id></element-citation></ref><ref id="B7"><label>7</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Spasojević</surname><given-names>I</given-names></name></person-group><article-title>Free radicals and antioxidants at a glance using EPR spectroscopy</article-title><source><italic>Critical Reviews in Clinical Laboratory Sciences</italic></source><year>2011</year><volume>48</volume><issue>3</issue><fpage>114</fpage><lpage>142</lpage><pub-id pub-id-type="other">2-s2.0-80052239721</pub-id><pub-id pub-id-type="pmid">21875311</pub-id></element-citation></ref><ref id="B8"><label>8</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Buettner</surname><given-names>GR</given-names></name><name><surname>Jurkiewicz</surname><given-names>BA</given-names></name></person-group><article-title>Catalytic metals, ascorbate and free radicals: combinations to avoid</article-title><source><italic>Radiation Research</italic></source><year>1996</year><volume>145</volume><issue>5</issue><fpage>532</fpage><lpage>541</lpage><pub-id pub-id-type="other">2-s2.0-0029939394</pub-id><pub-id pub-id-type="pmid">8619018</pub-id></element-citation></ref><ref id="B9"><label>9</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Buettner</surname><given-names>GR</given-names></name><name><surname>Jurkiewicz</surname><given-names>BA</given-names></name></person-group><article-title>Ascorbate free radical as a marker of oxidative stress: an EPR study</article-title><source><italic>Free Radical Biology and Medicine</italic></source><year>1993</year><volume>14</volume><issue>1</issue><fpage>49</fpage><lpage>55</lpage><pub-id pub-id-type="other">2-s2.0-0027469054</pub-id><pub-id pub-id-type="pmid">8384150</pub-id></element-citation></ref><ref id="B10"><label>10</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Chang</surname><given-names>TC</given-names></name><name><surname>Uen</surname><given-names>YH</given-names></name><name><surname>Chou</surname><given-names>CH</given-names></name><name><surname>Sheu</surname><given-names>JR</given-names></name><name><surname>Chou</surname><given-names>DS</given-names></name></person-group><article-title>The role of cyclooxygenase-derived oxidative stress in surgically induced lymphedema in a mouse tail model</article-title><source><italic>Pharmaceutical Biology</italic></source><year>2013</year><volume>51</volume><issue>5</issue><fpage>573</fpage><lpage>580</lpage><pub-id pub-id-type="pmid">23373707</pub-id></element-citation></ref><ref id="B14"><label>11</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Edderkaoui</surname><given-names>M</given-names></name><name><surname>Hong</surname><given-names>P</given-names></name><name><surname>Vaquero</surname><given-names>EC</given-names></name><etal></etal></person-group><article-title>Extracellular matrix stimulates reactive oxygen species production and increases pancreatic cancer cell survival through 5-lipoxygenase and NADPH oxidase</article-title><source><italic>American Journal of Physiology</italic></source><year>2005</year><volume>289</volume><issue>6</issue><fpage>G1137</fpage><lpage>G1147</lpage><pub-id pub-id-type="other">2-s2.0-28444499374</pub-id><pub-id pub-id-type="pmid">16037546</pub-id></element-citation></ref><ref id="B11"><label>12</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Hsieh</surname><given-names>C-Y</given-names></name><name><surname>Liu</surname><given-names>C-L</given-names></name><name><surname>Hsu</surname><given-names>M-J</given-names></name><etal></etal></person-group><article-title>Inhibition of vascular smooth muscle cell proliferation by the vitamin E derivative pentamethylhydroxychromane in an in vitro and in vivo study: pivotal role of hydroxyl radical-mediated PLC<italic>γ</italic>1 and JAK2 phosphorylation</article-title><source><italic>Free Radical Biology and Medicine</italic></source><year>2010</year><volume>49</volume><issue>5</issue><fpage>881</fpage><lpage>893</lpage><pub-id pub-id-type="other">2-s2.0-77955092406</pub-id><pub-id pub-id-type="pmid">20600839</pub-id></element-citation></ref><ref id="B12"><label>13</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Sakagami</surname><given-names>H</given-names></name><name><surname>Satoh</surname><given-names>K</given-names></name><name><surname>Ohata</surname><given-names>H</given-names></name><etal></etal></person-group><article-title>Relationship between ascorbyl radical intensity and apoptosis inducing activity</article-title><source><italic>Anticancer Research</italic></source><year>1996</year><volume>16</volume><issue>5 A</issue><fpage>2635</fpage><lpage>2644</lpage><pub-id pub-id-type="other">2-s2.0-10544220021</pub-id><pub-id pub-id-type="pmid">8917363</pub-id></element-citation></ref><ref id="B13"><label>14</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Vergely</surname><given-names>C</given-names></name><name><surname>Maupoil</surname><given-names>V</given-names></name><name><surname>Benderitter</surname><given-names>M</given-names></name><name><surname>Rochette</surname><given-names>L</given-names></name></person-group><article-title>Influence of the severity of myocardial ischemia on the intensity of ascorbyl free radical release and on postischemic recovery during reperfusion</article-title><source><italic>Free Radical Biology and Medicine</italic></source><year>1998</year><volume>24</volume><issue>3</issue><fpage>470</fpage><lpage>479</lpage><pub-id pub-id-type="other">2-s2.0-0031964491</pub-id><pub-id pub-id-type="pmid">9438560</pub-id></element-citation></ref><ref id="B30"><label>15</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Touyz</surname><given-names>RM</given-names></name><name><surname>Schiffrin</surname><given-names>EL</given-names></name></person-group><article-title>Reactive oxygen species in vascular biology: implications in hypertension</article-title><source><italic>Histochemistry and Cell Biology</italic></source><year>2004</year><volume>122</volume><issue>4</issue><fpage>339</fpage><lpage>352</lpage><pub-id pub-id-type="other">2-s2.0-8644277006</pub-id><pub-id pub-id-type="pmid">15338229</pub-id></element-citation></ref><ref id="B20"><label>16</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Hemila</surname><given-names>H</given-names></name></person-group><article-title>Vitamin C and the common cold</article-title><source><italic>The British Journal of Nutrition</italic></source><year>1992</year><volume>67</volume><fpage>3</fpage><lpage>16</lpage><pub-id pub-id-type="pmid">1547201</pub-id></element-citation></ref><ref id="B15"><label>17</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Kim</surname><given-names>C</given-names></name><name><surname>Dinauer</surname><given-names>MC</given-names></name></person-group><article-title>Impaired NADPH oxidase activity in Rac2-deficient murine neutrophils does not result from defective translocation of p47phox and p67 phox and can be rescued by exogenous arachidonic acid</article-title><source><italic>Journal of Leukocyte Biology</italic></source><year>2006</year><volume>79</volume><issue>1</issue><fpage>223</fpage><lpage>234</lpage><pub-id pub-id-type="other">2-s2.0-30144442688</pub-id><pub-id pub-id-type="pmid">16275890</pub-id></element-citation></ref><ref id="B16"><label>18</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Shiose</surname><given-names>A</given-names></name><name><surname>Sumimoto</surname><given-names>H</given-names></name></person-group><article-title>Arachidonic acid and phosphorylation synergistically induce a conformational change of p47(phox) to activate the phagocyte NADPH oxidase</article-title><source><italic>The Journal of Biological Chemistry</italic></source><year>2000</year><volume>275</volume><issue>18</issue><fpage>13793</fpage><lpage>13801</lpage><pub-id pub-id-type="other">2-s2.0-0034607649</pub-id><pub-id pub-id-type="pmid">10788501</pub-id></element-citation></ref><ref id="B17"><label>19</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Armstead</surname><given-names>WM</given-names></name><name><surname>Mirro</surname><given-names>R</given-names></name><name><surname>Busija</surname><given-names>DW</given-names></name><name><surname>Leffler</surname><given-names>CW</given-names></name></person-group><article-title>Postischemic generation of superoxide anion by newborn pig brain</article-title><source><italic>American Journal of Physiology</italic></source><year>1988</year><volume>255</volume><issue>2</issue><fpage>H401</fpage><lpage>H403</lpage><pub-id pub-id-type="other">2-s2.0-0023688174</pub-id><pub-id pub-id-type="pmid">2841877</pub-id></element-citation></ref><ref id="B18"><label>20</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Sato</surname><given-names>M</given-names></name><name><surname>Yokoyama</surname><given-names>U</given-names></name><name><surname>Fujita</surname><given-names>T</given-names></name><name><surname>Okumura</surname><given-names>S</given-names></name><name><surname>Ishikawa</surname><given-names>Y</given-names></name></person-group><article-title>The roles of cytochrome P450 in ischemic heart disease</article-title><source><italic>Current Drug Metabolism</italic></source><year>2011</year><volume>12</volume><issue>6</issue><fpage>526</fpage><lpage>532</lpage><pub-id pub-id-type="other">2-s2.0-79957947630</pub-id><pub-id pub-id-type="pmid">21476972</pub-id></element-citation></ref><ref id="B19"><label>21</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Jin</surname><given-names>G</given-names></name><name><surname>Arai</surname><given-names>K</given-names></name><name><surname>Murata</surname><given-names>Y</given-names></name><etal></etal></person-group><article-title>Protecting against cerebrovascular injury: contributions of 12/15-lipoxygenase to edema formation after transient focal ischemia</article-title><source><italic>Stroke</italic></source><year>2008</year><volume>39</volume><issue>9</issue><fpage>2538</fpage><lpage>2543</lpage><pub-id pub-id-type="other">2-s2.0-52449086378</pub-id><pub-id pub-id-type="pmid">18635843</pub-id></element-citation></ref><ref id="B21"><label>22</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Turrens</surname><given-names>JF</given-names></name></person-group><article-title>Mitochondrial formation of reactive oxygen species</article-title><source><italic>Journal of Physiology</italic></source><year>2003</year><volume>552</volume><issue>2</issue><fpage>335</fpage><lpage>344</lpage><pub-id pub-id-type="other">2-s2.0-0142150051</pub-id><pub-id pub-id-type="pmid">14561818</pub-id></element-citation></ref><ref id="B33"><label>23</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Higashi</surname><given-names>Y</given-names></name><name><surname>Peng</surname><given-names>T</given-names></name><name><surname>Du</surname><given-names>J</given-names></name><etal></etal></person-group><article-title>A redox-sensitive pathway mediates oxidized LDL-induced downregulation of insulin-like growth factor-1 receptor</article-title><source><italic>Journal of Lipid Research</italic></source><year>2005</year><volume>46</volume><issue>6</issue><fpage>1266</fpage><lpage>1277</lpage><pub-id pub-id-type="other">2-s2.0-24944450780</pub-id><pub-id pub-id-type="pmid">15805544</pub-id></element-citation></ref><ref id="B34"><label>24</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Pallast</surname><given-names>S</given-names></name><name><surname>Arai</surname><given-names>K</given-names></name><name><surname>Wang</surname><given-names>X</given-names></name><name><surname>Lo</surname><given-names>EH</given-names></name><name><surname>Van Leyen</surname><given-names>K</given-names></name></person-group><article-title>12/15-Lipoxygenase targets neuronal mitochondria under oxidative stress</article-title><source><italic>Journal of Neurochemistry</italic></source><year>2009</year><volume>111</volume><issue>3</issue><fpage>882</fpage><lpage>889</lpage><pub-id pub-id-type="other">2-s2.0-70349898267</pub-id><pub-id pub-id-type="pmid">19737346</pub-id></element-citation></ref><ref id="B22"><label>25</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Schächinger</surname><given-names>V</given-names></name><name><surname>Britten</surname><given-names>MB</given-names></name><name><surname>Zeiher</surname><given-names>AM</given-names></name></person-group><article-title>Prognostic impact of coronary vasodilator dysfunction on adverse long- term outcome of coronary heart disease</article-title><source><italic>Circulation</italic></source><year>2000</year><volume>101</volume><issue>16</issue><fpage>1899</fpage><lpage>1906</lpage><pub-id pub-id-type="other">2-s2.0-0342424181</pub-id><pub-id pub-id-type="pmid">10779454</pub-id></element-citation></ref><ref id="B23"><label>26</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Münzel</surname><given-names>T</given-names></name><name><surname>Gori</surname><given-names>T</given-names></name><name><surname>Bruno</surname><given-names>RM</given-names></name><name><surname>Taddei</surname><given-names>S</given-names></name></person-group><article-title>Is oxidative stress a therapeutic target in cardiovascular disease?</article-title><source><italic>European Heart Journal</italic></source><year>2010</year><volume>31</volume><issue>22</issue><fpage>2741</fpage><lpage>2749</lpage><pub-id pub-id-type="other">2-s2.0-78649357316</pub-id><pub-id pub-id-type="pmid">20974801</pub-id></element-citation></ref><ref id="B24"><label>27</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Sies</surname><given-names>H</given-names></name></person-group><article-title>Oxidative stress: from basic research to clinical application</article-title><source><italic>American Journal of Medicine</italic></source><year>1991</year><volume>91</volume><issue>3</issue><fpage>31S</fpage><lpage>38S</lpage><pub-id pub-id-type="other">2-s2.0-13644284442</pub-id></element-citation></ref><ref id="B25"><label>28</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Fortuño</surname><given-names>A</given-names></name><name><surname>San José</surname><given-names>G</given-names></name><name><surname>Moreno</surname><given-names>MU</given-names></name><name><surname>Díez</surname><given-names>J</given-names></name><name><surname>Zalba</surname><given-names>G</given-names></name></person-group><article-title>Oxidative stress and vascular remodelling</article-title><source><italic>Experimental Physiology</italic></source><year>2005</year><volume>90</volume><issue>4</issue><fpage>457</fpage><lpage>462</lpage><pub-id pub-id-type="other">2-s2.0-22144494121</pub-id><pub-id pub-id-type="pmid">15890797</pub-id></element-citation></ref><ref id="B32"><label>29</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Foster</surname><given-names>MA</given-names></name><name><surname>Pocklington</surname><given-names>T</given-names></name><name><surname>Miller</surname><given-names>JDB</given-names></name><name><surname>Mallard</surname><given-names>JR</given-names></name></person-group><article-title>A study of electron spin resonance spectra of whole blood from normal and tumour bearing patients</article-title><source><italic>British Journal of Cancer</italic></source><year>1973</year><volume>28</volume><issue>4</issue><fpage>340</fpage><lpage>348</lpage><pub-id pub-id-type="other">2-s2.0-0015842639</pub-id><pub-id pub-id-type="pmid">4357272</pub-id></element-citation></ref><ref id="B26"><label>30</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Cai</surname><given-names>H</given-names></name><name><surname>Harrison</surname><given-names>DG</given-names></name></person-group><article-title>Endothelial dysfunction in cardiovascular diseases: the role of oxidant stress</article-title><source><italic>Circulation Research</italic></source><year>2000</year><volume>87</volume><issue>10</issue><fpage>840</fpage><lpage>844</lpage><pub-id pub-id-type="other">2-s2.0-0034634281</pub-id><pub-id pub-id-type="pmid">11073878</pub-id></element-citation></ref><ref id="B27"><label>31</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Münzel</surname><given-names>T</given-names></name><name><surname>Daiber</surname><given-names>A</given-names></name><name><surname>Ullrich</surname><given-names>V</given-names></name><name><surname>Mülsch</surname><given-names>A</given-names></name></person-group><article-title>Vascular consequences of endothelial nitric oxide synthase uncoupling for the activity and expression of the soluble guanylyl cyclase and the CGMP-dependent protein kinase</article-title><source><italic>Arteriosclerosis, Thrombosis, and Vascular Biology</italic></source><year>2005</year><volume>25</volume><issue>8</issue><fpage>1551</fpage><lpage>1557</lpage><pub-id pub-id-type="other">2-s2.0-23244459293</pub-id></element-citation></ref><ref id="B28"><label>32</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Zweier</surname><given-names>JL</given-names></name><name><surname>Talukder</surname><given-names>MAH</given-names></name></person-group><article-title>The role of oxidants and free radicals in reperfusion injury</article-title><source><italic>Cardiovascular Research</italic></source><year>2006</year><volume>70</volume><issue>2</issue><fpage>181</fpage><lpage>190</lpage><pub-id pub-id-type="other">2-s2.0-33646055216</pub-id><pub-id pub-id-type="pmid">16580655</pub-id></element-citation></ref><ref id="B29"><label>33</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Münzel</surname><given-names>T</given-names></name><name><surname>Sinning</surname><given-names>C</given-names></name><name><surname>Post</surname><given-names>F</given-names></name><name><surname>Warnholtz</surname><given-names>A</given-names></name><name><surname>Schulz</surname><given-names>E</given-names></name></person-group><article-title>Pathophysiology, diagnosis and prognostic implications of endothelial dysfunction</article-title><source><italic>Annals of Medicine</italic></source><year>2008</year><volume>40</volume><issue>3</issue><fpage>180</fpage><lpage>196</lpage><pub-id pub-id-type="other">2-s2.0-41649116606</pub-id><pub-id pub-id-type="pmid">18382884</pub-id></element-citation></ref><ref id="B31"><label>34</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Radomski</surname><given-names>MW</given-names></name><name><surname>Palmer</surname><given-names>RMJ</given-names></name><name><surname>Moncada</surname><given-names>S</given-names></name></person-group><article-title>An L-arginine/nitric oxide pathway present in human platelets regulates aggregation</article-title><source><italic>Proceedings of the National Academy of Sciences of the United States of America</italic></source><year>1990</year><volume>87</volume><issue>13</issue><fpage>5193</fpage><lpage>5197</lpage><pub-id pub-id-type="other">2-s2.0-0025366847</pub-id><pub-id pub-id-type="pmid">1695013</pub-id></element-citation></ref></ref-list></back><floats-group><fig id="fig1" orientation="portrait" position="float"><label>Figure 1</label><caption><p>Free radical doublet (a) detected using ESR spectroscopy in (A) PPP, (B) PRP, (C) RBCs, and (D) whole blood. The ESR signal was examined at room temperature, and the following instrument parameters were used in ESR spectroscopy: standard frequency (X-band): 9 GHz; microwave power: 20 mW; modulation frequency: 100 kHz; time constant: 163.84 ms; conversion time: 40.96 ms; receiver gain: 5.02 × 10<sup>5</sup>; and the number of data X-scans: 4. The free radical doublet is marked with arrows: “↓”. Effect of ascorbic acid on the <italic>g</italic> = 2.00627 radical formation in human PRP. The intensity of the <italic>g</italic> = 2.00627 radical obtained from the reaction of PRP (approximately 8 × 10<sup>6</sup> cells/mL, control) and 30 <italic>μ</italic>M, 100 <italic>μ</italic>M, 300 <italic>μ</italic>M, and 1000 <italic>μ</italic>M ascorbic acid in the presence of 100 mM DMPO. ESR analysis was exactly 30 s after the final addition. ESR spectra are labeled to show their components: DMPO- Asc<sup>∙</sup> adduct (∗). The values of the ESR signal intensity in the bar chart (b) are shown as the means ± SEM (<italic>n</italic> = 4). ***<italic>P</italic> < 0.001 compared with the control. The instrument parameters were identical to those shown in (a).</p></caption><graphic xlink:href="BMRI2014-614506.001"></graphic></fig><fig id="fig2" orientation="portrait" position="float"><label>Figure 2</label><caption><p>Effect of superoxide and the nitric oxide scavenger on Asc<sup>∙</sup> formation in human PRP. ESR spectra (a) obtained from the reaction of (A) PRP (approximately 8 × 10<sup>6</sup> cells/mL) and (B) superoxide scavenger (120 U/mL SOD and 1000 U/mL CAT) and the (C) nitric oxide scavenger (1 <italic>μ</italic>g/mL of hemoglobin) in the presence of 100 mM DMPO for 3 min. The ESR spectra are labeled to show their components: DMPO- Asc<sup>∙</sup> adduct (∗). The ESR signal intensity rates in the bar chart (b) are shown as the means ± SEM (<italic>n</italic> > 3). **<italic>P</italic> < 0.01, *<italic>P</italic> < 0.05 compared with the control. The instrument parameters were identical to those shown in <xref ref-type="fig" rid="fig1">Figure 1(a)</xref>.</p></caption><graphic xlink:href="BMRI2014-614506.002"></graphic></fig><fig id="fig3" orientation="portrait" position="float"><label>Figure 3</label><caption><p>Effect of the NOX inhibitor (a), XO inhibitor (b), and NOS inhibitor (c) on Asc<sup>∙</sup> formation in human PRP (approximately 8 × 10<sup>6</sup> platelets/mL). The ESR signal intensity rates in the bar chart are expressed as the means ± SEM (<italic>n</italic>≧5). ***<italic>P</italic> < 0.001, *<italic>P</italic> < 0.05 compared with the solvent control. The instrument parameters were identical to those shown in <xref ref-type="fig" rid="fig1">Figure 1(a)</xref>.</p></caption><graphic xlink:href="BMRI2014-614506.003"></graphic></fig><fig id="fig4" orientation="portrait" position="float"><label>Figure 4</label><caption><p>Effect of AA (a) and the PLA<sub>2</sub> inhibitor (b) on Asc<sup>∙</sup> formation in human PRP (approximately 8 × 10<sup>6</sup> platelets/mL). The ESR signal intensity and data in the bar chart are expressed as the means ± SEM (<italic>n</italic>≧5). *<italic>P</italic> < 0.05, ***<italic>P</italic> < 0.001 compared with the solvent control group. The instrument parameters were identical to those shown in <xref ref-type="fig" rid="fig1">Figure 1(a)</xref>.</p></caption><graphic xlink:href="BMRI2014-614506.004"></graphic></fig><fig id="fig5" orientation="portrait" position="float"><label>Figure 5</label><caption><p>Effect of the COX inhibitor (a), LOX inhibitor (b), and CYP450 inhibitor (c) on Asc<sup>∙</sup> formation in human PRP (approximately 8 × 10<sup>6</sup> platelets/mL). The ESR spectra are labeled to show their components: DMPO- Asc<sup>∙</sup> adduct (∗). The ESR signal intensity rates and data in the bar chart are expressed as the means ± SEM (<italic>n</italic>≧4). **<italic>P</italic> < 0.01, *<italic>P</italic> < 0.05 compared with the solvent control. The instrument parameters were identical to those shown in <xref ref-type="fig" rid="fig1">Figure 1(a)</xref>.</p></caption><graphic xlink:href="BMRI2014-614506.005"></graphic></fig><fig id="fig6" orientation="portrait" position="float"><label>Figure 6</label><caption><p>Effect of the mitochondrial complex III inhibitor on Asc<sup>∙</sup> formation in human PRP. The ESR spectra show (a) the effect of a solvent control, (A) 0.6% DMSO, and 10, 30 (data not shown), and (B) 100 <italic>μ</italic>M antimycin in the presence of 100 mM DMPO for 30 min on Asc<sup>∙</sup> formation in human PRP (approximately 8 × 10<sup>6</sup> platelets/mL). The ESR spectra are labeled to show their components: DMPO- Asc<sup>∙</sup> adduct (∗). The ESR signal intensity rate and data shown in the bar chart (b) are expressed as the means ± SEM (<italic>n</italic> = 6). ***<italic>P</italic> < 0.001 compared with the solvent control. The instrument parameters were identical to those shown in <xref ref-type="fig" rid="fig1">Figure 1</xref>.</p></caption><graphic xlink:href="BMRI2014-614506.006"></graphic></fig><fig id="fig7" orientation="portrait" position="float"><label>Figure 7</label><caption><p>Effect of the fat-soluble (a) and water-soluble (b) enzyme inhibitor on hydroxyl free radical formation in the Fenton reaction. (a) The effect of the Fenton reaction solution (500 <italic>μ</italic>M hydrogen peroxide + 50 <italic>μ</italic>M FeSO<sub>4</sub>, positive control), 0.6% DMSO, 10 <italic>μ</italic>M DPI, 10 <italic>μ</italic>M AA861, 10 <italic>μ</italic>M L-NAME, 10 <italic>μ</italic>M allopurinol, 10 <italic>μ</italic>M clotrimazole, and 10 <italic>μ</italic>M indomethacin in the presence of 150 mM DMPO for 3 min on hydroxyl radical formation. (b) The effect of the Fenton reaction solution (positive control), 10 <italic>μ</italic>M quinacrine, and 100 <italic>μ</italic>M antimycin in the presence of 150 mM DMPO for 3 min on hydroxyl radical formation. The signal intensity rates and data shown in the bar chart are expressed as the means ± SEM (<italic>n</italic>≧3). <italic>P</italic> > 0.05 compared with the solvent control. The instrument parameters were identical to those shown in <xref ref-type="fig" rid="fig1">Figure 1(a)</xref>.</p></caption><graphic xlink:href="BMRI2014-614506.007"></graphic></fig><fig id="fig8" orientation="portrait" position="float"><label>Figure 8</label><caption><p>Proposed pathway for the mechanisms of Asc<sup>∙</sup> formation in human PRP (O<sub>2</sub><sup>∙−</sup>; superoxide anion; NO; nitric oxide).</p></caption><graphic xlink:href="BMRI2014-614506.008"></graphic></fig></floats-group></pmc></record>Pour manipuler ce document sous Unix (Dilib)
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