5‐羟色胺（5-HT）是一种强有力的血管活性神经递质，被广泛的应用在调节血管张力。当5‐HT 被释放后，会被单胺氧化酶（MAOs）催化的酶促反应代谢，从而产生不同的代谢产物，比如5‐HIAA，5‐HTOL 和过氧化氢（H₂O₂）。然而，5‐HT对于内皮细胞活性氧物种（ROS）的产生作用以及5‐HT 转运体，5‐HT 受体，MAOs和ROS 的产生伴随着细胞内钙变化是否参与了其中的信号传导尚未被阐明。所以，这个研究最初的目的是考查外源性加入的5‐HT 对于脐静脉内皮细胞中ROS产生的影响以及其潜在的生物机理。 / 数据清楚的显示在没有L‐NAME（一种抑制一氧化氮（NO）产生的抑制剂）预处理的情况下，5‐HT 并不能在脐静脉内皮细胞内产生显著性的ROS。然而，在L‐NAME 预处理的情况下，NO 的产生被完全抑制，我们观察到明显的显著性的线粒体内的ROS 产生。5‐HT 产生的线粒体ROS 可以被clorgyline（一种MAO‐A 抑制剂），indatraline（一种5‐HT 转运体阻断剂），LY272015（一种5‐HT‐2B 受体拮抗剂），ketanserin（一种5‐HT2A 受体拮抗剂），XeC（一种IP3 受体拮抗剂），Gd³⁺（一种非选择性TRP 通道阻断剂），BAPTA（一种强效钙离子螯合剂），PEG‐Catalase，U73122（一种选择性PLC 抑制剂）以及没有钙离子的培养基所阻止。同时，5‐HT介导的胞内钙离子变化被XeC, Gd³⁺, BAPTA, U73122, ketanserin, LY272015 以及没有钙离子的培养基所阻止。另外，MAO‐A 基因敲除抑制了5‐HT 导致的线粒体ROS的产生却对5‐HT 介导的胞内钙离子变化没有影响。基于以上所述的结果，我们可以得出结论，通过5‐HT 转运体，5‐HT 被摄取入细胞内，然后通过MAO‐A 介导的酶促代谢反应，产生钙离子依赖性的线粒体内ROS 的产生，这一结论对于解释血小板聚集而引起的内皮细胞功能性障碍起到非常重要的作用。 / 根据前人所述，内皮细胞内产生的ROS 对于内皮细胞通透性变化有着重要的作用，但是5‐HT 诱导的脐静脉内皮细胞ROS 的增加是否会对内皮通透性有所影响并没有被说明。在这项研究中，我们设计了实验旨在测试平面细胞表面积（ PCSA ）， 跨内皮电阻（ TER ）， 细胞高度， 肌球蛋白轻链磷酸化（MLCphosphorylation）和肌动蛋白细胞骨架（F‐actin cytoskeleton）水平的变化。此外，b‐catenin 在ROS 引起的F‐actin cytoskeleton 重组中的作用也在我们的讨论范围之内。 / 数据表明，在L‐NAME 预处理的情况下，5-HT 降低了脐静脉内皮的PCSA，TER 以及细胞高度，却增加了MLCP 和与b‐catenin 表达负相关的F‐actincytoskeleton 的水平。这些作用明显被PEG‐Catalase 预处理和MAO‐A 基因敲除减弱，证明了5‐HT 通过MAO‐A 介导产生的H₂O₂ 可以增加内皮细胞的通透性。 / 据文献报道，不论内源性还是外源性的低浓度的H₂O₂ 都可以激活导致血管生成的信号通路。文献进一步表明5‐HT 可以通过特定的5‐HT 受体亚型促进各种类型的内皮细胞的血管生成。然而，5‐HT 诱导的H₂O₂ 对于脐静脉内皮的血管生成作用并没有被报道。我们通过最初的实验先验证5‐HT 对于内皮细胞增殖和迁移的影响，然后我们才去验证H₂O₂ 在其中的作用及其潜在的机理。 / 实验结果表明，在L‐NAME 预处理的情况下，不论是急性（30 分钟）还是慢性（24 小时）的5‐HT 的处理都可以导致脐静脉内皮细胞的迁移，而这个作用会被5‐HT‐2 受体拮抗剂ketanserin，LY272015，ROS 清除剂PEG‐Catalase 以及PI3K的抑制剂wortmannin 所抑制。同时，在L‐NAME 预处理下，5‐HT 增加了cortactin,p‐Akt 和 p‐eNOS 的蛋白表达量而并没有影响Akt, eNOS 和p‐cortactin 的蛋白表达量。而5‐HT 增加的p‐Akt 和p‐eNOS 的蛋白表达被wortmannin 和PEG‐Catalase所抑制。不论是在Cyuant 细胞增殖检测还是在BrdU 细胞增殖检测中，5‐HT 诱导了一种非显著性的DNA 合成的增加，并且再BrdU 细胞增殖检测中，增加了的DNA 合成被PEG‐Catalase 显著性降低。总结以上实验结果，我们可以得出结论，通过一种5‐HT‐2 受体介导的PI3K 依赖性通路，而不是cortactin 磷酸化依赖性的信号通，路5‐HT 可以引导内皮细胞迁移。 / 除此之外，ROS 也被印证可以加剧内皮细胞的炎症反应和加速内皮细胞的老化。因此，我们也观察了5‐HT 对于粘附蛋白比如ICAM‐1 和VCAM‐1 以及抗老化因子SIRT‐1 的表达是否有影响。数据表明，在L‐NAME 预处理的情况下，30 分钟的5‐HT 处理显著的增加了ICAM‐1，SIRT‐1 而不是VCAM‐1 的表达。同时，这些作用均可以被PEG‐Catalase 所抑制表明了5‐HT 通过诱导H₂O₂ 的产生来形式其促进炎症反应和抗衰老的作用。 / 最后，总结以上，通过抑制NO 的产生，5‐HT 可以通过MAO‐A 介导的酶促代谢反应在人体脐静脉内皮细胞线粒体诱导ROS 的产生。同时，5‐HT 诱导的H₂O₂参与了改变内皮细胞通透性，促进血管生成（内皮迁移）及炎症反应的过程。 / 5-Hydroxytryptamine (5-HT), a potent vasoactive neurotransmitter, is involved in the regulation of vascular tone. After its release, 5-HT is terminated at the nerve terminals via enzymatic metabolism catalyzed by monoamine oxidases (MAOs), resulting in the generation of different metabolites (e.g. 5-HIAA, 5-HTOL and H₂O₂). Our lab demonstrates for the first time that 5-HT-induced ROS production indeed occurs and therefore, the aim of this study is to investigate exogenously added 5-HT on ROS generation in human umbilical vein endothelial cells (HUVECs), in order to understand the mechanisms involved in 5-HT-induced ROS production. / Our results clearly demonstrated that in the absence of L-NAME(a NO production inhibitor), there wasno apparent ROS production induced by 5-HT. However, after the inhibition of NO synthesis by L-NAME, 5-HT caused a significant increase in mitochondrial H₂O₂ production. The 5-HT-induced mitochondrial H₂O₂ generation was sensitive to clorgyline (a MAO-A inhibitor), indatraline (a 5-HT transporter blocker), LY272015 (a 5-HT2B antagonist) and ketanserin (a 5-HT2A antagonist), Xextospongin C（XeC，a IP3 receptor antagonist), Gd³⁺ (a non-selective TRP channel blocker), BAPTA (a potent Ca²⁺ ions chelator), PEG-Catalase, U73122 (a selective PLC inhibitor), and in [Ca²⁺]o-free medium. Concurrently, 5-HT-mediated [Ca²⁺]i changes were sensitive to XeC, Gd³⁺, BAPTA, U73122, ketanserin, LY272015, and in [Ca²⁺]o-free conditions. In addition, gene knockdown of MAO-A suppressed 5-HT-elicited H₂O₂ production with no effects on [Ca²⁺]i changes. Based on all the results above, we can conclude that 5-HT caused a Ca²⁺-dependent mitochondrial H₂O₂ generation via MAO-A-mediated metabolism with the pre-requisite uptake of 5-HT into HUVECs through 5-HT transporter. / ROS derived from endothelial cells have been implicated in changes in endothelial permeability, but whether 5-HT-induced H₂O₂ generation could alter endothelial cells permeability has as yet not been demonstrated. Here, we measured the planar cell surface area (PCSA), transendothelial electrical resistance (TER), cell height, myosin light chain phosphorylation and F-actin cytoskeleton level in response to 5-HT challenge to investigate the change of endothelial permeability. Moreover, the participation of β-catenin in regulation of F-actin cytoskeleton remodeling in ROS-modulated alteration in endothelial permeability was also investigated. Results indicated that in the presence of L-NAME, 5-HT reduced the PCSA, TER and cell height in HUVECs. In contrast, 5-HT (with L-NAME) increased myosin light chain phosphorylation (MLCP) expression and F-actin cytoskeleton level, which are negatively associated with β-catenin expression. All of these effects were ameliorated by pre-treatment of PEG-Catalase or gene knockdown of MAO-A, implying 5-HT can consistently elicit the increase in endothelial permeability via MAO-A mediated H₂O₂ generation. / Low dose of ROS from exogenous or endogenous source can activate signaling pathway that lead to angiogenesis.5-HT can promote endothelial angiogenesis through specific 5-HT receptor subtype in various endothelial cell types, but the concomitant ROS generation had not previously been indicated to play a role in the process. In this study, we seek to test out the effects of 5-HT on endothelial cells migration, and should there be a functional role for ROS in the process. / Our results revealed that in the presence of L-NAME, both acute (30 min) and chronic (24 hr) treatment of 5-HT caused HUVECs migration, the effects of which were reversed by pre-incubation of 5-HT-2 receptor antagonists, ketanserin, LY272015, ROS scavenger PEG-Catalase or selective PI3K inhibitor wortmannin. With L-NAME, 5-HT consistently increased cortactin, p-Akt and p-eNOS expression without affecting total Akt, eNOS and p-cortactin protein expression whereas the increased p-Akt and p-eNOS expression are suppressed by pre-treatment of wortmanin or PEG-Catalase. Both in Cyuant cell proliferation assay and BrdU assay, 5-HT caused a trend but non-significant increase in DNA synthesis whereas the pre-treatment of PEG-Catalase significantly suppressed cell proliferation in the BrdU assay. Based on these results, we can conclude that 5-HT elicits endothelial migration via 5-HT-2 receptor-mediated H₂O₂ generation in a PI3K-dependent pathway. Under this circumstance, cortactin phosphorylation-dependent pathway was excluded. / Besides, ROS is notorious for effects like aggravation of inflammation and acceleration aging processes. The investigation extends to looking at alterations ofexpression of adhesion protein including ICAM-1 and VCAM-1 in the inflammatory response pathway and also to looking at the major aging parameter SIRT-1 in the presence of 5-HT in endothelium. Our data showed that in the presence of L-NAME, 30 min treatment of 5-HT significantly increased ICAM-1 and SIRT-1 expression without altering VCAM-1 expression and the up-regulation of ICAM-1 and SIRT-1 expression was prevented by PEG-Catalase. / In conclusion, with the eradication of the influence of NO, 5-HT induced mitochondrial H₂O₂ production via MAO-A-mediated metabolism in HUVECs. At the same time, 5-HT-induced H₂O₂ generation was involved in increasing endothelial permeability, inflammation and angiogenesis (cell migration). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Zhang, Qian. / Thesis (Ph.D.) Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 326-450). / Abstracts also in Chinese. / Zhang, Qian.

Existem muitas metodologias utilizadas para tentar analisar a permeação de peróxido de hidrogênio através das estruturas dentárias, porém não conseguem determinar o momento exato em que o peróxido começa a alcançar concentrações detectáveis dentro da câmara pulpar. OBJETIVO: Investigar a viabilidade de um modelo experimental de análise eletroquímica para detecção e mensuração da concentração de peróxido de hidrogênio proveniente de produtos utilizados em tratamento clareador e avaliar a cinética da difusão destes peróxidos através dos tecidos duros dentários. MATERIAIS E MÉTODOS: Foram utilizados 45 dentes incisivos bovinos permanentes mandibulares, cujo preparo envolveu a remoção da face lingual coronária, mantendo-se o esmalte e a dentina vestibulares intactos. Todos os dentes foram fixados em resina acrílica com auxílio de matriz elastomérica quadrangular e organizados segundo os testes: 1: análise eletroquímica e 2: análise espectrofotométrica. Para os testes foram utilizados clareadores à base de peróxido de hidrogênio (HP) e de peróxido de carbamida (CP) e seus respectivos placebos (PHP e PCP). Foram realizados três cronoamperogramas e três voltamogramas para cada uma das amostras. Utilizou-se a mesma cela no experimento eletroquímico e no teste espectrofotométrico, permitindo assim a comparação das metodologias. RESULTADOS: A análise eletroquímica mostrou na 1ª permeação de HP média de 1688,50 segundos quando comparada a 857,70s e a 457,70s da 2ª e da 3ª permeações, respectivamente. Desta forma observa-se que a 1ª permeação representa aproximadamente o dobro e o quadruplo dos valores sequenciais da 2ª e da 3ª permeações. Não foi detectado início de permeação para CP, PHP e PCP. Para o grupo HP há uma relação crescente nas concentrações de moléculas de peróxido de hidrogênio detectadas nas três permeações respectivamente. Entretanto, o crescimento entre a 1ª e 2ª permeação é discreto, quando comparado à 3ª permeação, onde foi detectada maior concentração de moléculas do peróxido de hidrogênio. No grupo CP observam-se médias de 2,96E-02 A na 1ª permeação, 3,11E-05 A na 2ª permeação e 1,37E-04 A na 3ª permeação, havendo diferença entre a 1ª e 3ª permeação (p = 0,00472). Todavia, não ocorreram diferenças entre os demais grupos (p > 0,05). Quando comparado o método eletroquímico e o método espectrofotométrico, o peróxido de hidrogênio (HP) não demonstrou diferença significativa entre as análises (p =0,0826); todavia o peróxido de carbamida mostrou diferenças entre as duas análises (p=0,0093). CONCLUSÕES: A metodologia eletroquímica é tão eficaz quanto à metodologia consolidada na literatura para a detecção da presença de peróxido de hidrogênio na câmara pulpar, nos testes com peróxido de hidrogênio 35%. O tempo necessário para que o peróxido de hidrogênio chegasse à câmara pulpar diminuiu a cada aplicação e a penetração do peróxido de hidrogênio aumentou a permeabilidade dos tecidos duros dentais. / There are many methods used to analyze the permeation of hydrogen peroxide through the tooth structure, but they cannot determine the exact moment when the peroxide begins to reach detectable concentrations within the pulp chamber. OBJECTIVE: To investigate the feasibility of an experimental model of electrochemical analysis for detection and measurement of the concentration of hydrogen peroxide from products used in bleaching and evaluate the kinetics of diffusion of these peroxides through dental hard tissues. MATERIALS AND METHODS: We used 45 bovine permanent mandibular incisors, whose preparation involved removing the lingual coronary hard tissues keeping intact the vestibular enamel and dentin. All teeth were fixed in acrylic resin with the aid of elastomeric matrix square and organized according to the tests: 1: electrochemical analysis and 2: spectrophotometric analysis. For tests were used based bleaching hydrogen peroxide (HP) and carbamide peroxide (CP) and their respective placebos (PHP and PCP). Three cronoamperograms and three voltammograms were performed for each sample. We used the same cell to the spectrophotometric test, thus allowing comparison of methodologies. RESULTS: The analysis showed the 1st electrochemical permeation HP average of 1688.50 seconds when compared to 857.70s and 457.70s of the 2nd and 3rd permeations respectively. Thus we observe that the 1st permeation is approximately double and quadruple sequential values of the 2nd and the 3rd permeations. Not detected early permeation for CP, PHP and PCP. For Group HP there is a ratio of molecules increasing concentrations of hydrogen peroxide detected in three permeations respectively. However, the growth between the 1st and 2nd permeation is understated when compared to 3rd permeation, where there has been a greater concentration of molecules of hydrogen peroxide. In the CP group were observed averages of 2.96 E-02A in the 1st permeation, 3.11 E-05 A in the 2nd permeation and 1.37 E-04 A in 3rd permeation, no difference between 1st and 3rd permeation (p = 0.00472) . However, there were no differences between the other groups (p> 0.05). When compared the electrochemical and spectrophotometric methods, hydrogen peroxide (HP) showed no significant difference between the analysis (p = 0.0826), yet the carbamide peroxide showed differences between the two analyzes (p = 0.0093). CONCLUSIONS: The electrochemical method is as effective as the consolidated methodology in the literature to detect the presence of hydrogen peroxide in the pulp chamber, in the tests with hydrogen peroxide 35%. The time required for the hydrogen peroxide to reach the pulp chamber decreased to each application and the penetration of hydrogen peroxide increased the permeability of dental hard tissues.

Ho, Ka Yan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 111-124). / Abstracts in English and Chinese. / Thesis committee --- p.i / Acknowledgements --- p.ii / Abstract --- p.iii / 摘要 --- p.v / List of Tables --- p.vii / List of Figures --- p.viii / Abbreviations --- p.x / Content --- p.xiii / Chapter Chapter 1: --- Introduction --- p.1 / Chapter 1.1 --- Reactive oxygen species (ROS) --- p.1 / Chapter 1.1.1 --- Definition and examples --- p.1 / Chapter 1.1.2 --- Generation of ROS in biological systems --- p.2 / Chapter 1.1.3 --- Features of specif ic ROS --- p.3 / Chapter 1.1.3.1 --- Superoxide anion --- p.3 / Chapter 1.1.3.2 --- Peroxyl radical --- p.4 / Chapter 1.1.3.3 --- Hydrogen peroxide --- p.4 / Chapter 1.1.3.4 --- Hydroxyl radical --- p.5 / Chapter 1.1.4 --- Damaging effects of ROS on biomolecules --- p.5 / Chapter 1.1.4.1 --- Lipid peroxidation --- p.6 / Chapter 1.1.4.2 --- DNA damage --- p.8 / Chapter 1.1.4.3 --- Protein oxidation --- p.9 / Chapter 1.2 --- Antioxidants --- p.11 / Chapter 1.2.1 --- Introduction --- p.11 / Chapter 1.2.2 --- Mode of action --- p.11 / Chapter 1.2.3 --- Endogenous Antioxidants --- p.12 / Chapter 1.2.3.1 --- Antioxidant enzymes --- p.12 / Chapter 1.2.3.2 --- Antioxidant compounds --- p.15 / Chapter 1.2.4 --- Exogenous antioxidants --- p.16 / Chapter 1.3 --- Oxidative stress --- p.17 / Chapter 1.3.1 --- Balance between ROS and antioxidants --- p.17 / Chapter 1.3.2 --- Diseases associated with oxidative stress --- p.18 / Chapter 1.4 --- Previous studies on edible mushroom antioxidants --- p.19 / Chapter 1.4.1 --- Previous studies on Agrocybe aegerita --- p.20 / Chapter 1.5 --- Cell culture models for antioxidant research --- p.21 / Chapter 1.6 --- Objectives --- p.23 / Chapter Chapter 2 --- Materials and Methods --- p.24 / Chapter 2.1 --- Materials --- p.24 / Chapter 2.1.1 --- Mushroom fruiting bodies --- p.24 / Chapter 2.1.2 --- Cell lines and their subcultures --- p.24 / Chapter 2.2 --- Principle of Methods and Procedures --- p.26 / Chapter 2.2.1 --- Sample preparation and extraction --- p.26 / Chapter 2.2.2 --- Chemical assays for in vitro antioxidative properties of mushroom extracts --- p.28 / Chapter 2.2.2.1 --- ABTS + scavenging activity --- p.28 / Chapter 2.2.2.2 --- Hydroxyl radical scavenging activity --- p.30 / Chapter 2.2.2.3 --- Hydrogen peroxide scavenging activity --- p.32 / Chapter 2.2.3 --- Total phenolic content --- p.34 / Chapter 2.2.4 --- Cytotoxicity of hydrogen peroxide --- p.36 / Chapter 2.2.5 --- Cytoprotectivity of mushroom extracts --- p.36 / Chapter 2.2.6 --- "Colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay" --- p.37 / Chapter 2.2.7 --- Lactate dehydrogenase (LDH) assay --- p.39 / Chapter 2.2.8 --- Total cellular protein loss --- p.40 / Chapter 2.2.9 --- Comet assay (Single cell gel electrophresis assay) --- p.41 / Chapter 2.2.10 --- Thiobarbituric Acid Reactive Substances (TBARS) assay ..… --- p.44 / Chapter 2.2.11 --- Preparation of cell lysate for evaluating cellular antioxidant defense system --- p.45 / Chapter 2.2.12 --- Total Glutathione level --- p.46 / Chapter 2.2.13 --- Enzyme activity --- p.49 / Chapter 2.2.13.1 --- Catalase (CAT) --- p.49 / Chapter 2.2.13.2 --- Glutathione peroxidases (GPx) --- p.51 / Chapter 2.2.13.3 --- Glutathione Reductase (GR) --- p.53 / Chapter 2.2.13.4 --- Superoxide dismutase (SOD) --- p.54 / Chapter 2.2.14 --- Determination of protein --- p.56 / Chapter 2.2.15 --- Statistical analysis --- p.56 / Chapter Chapter 3 --- Results and discussions --- p.57 / Chapter 3.1 --- Extraction yield --- p.57 / Chapter 3.2 --- Chemical assays for in vitro antioxidative properties of mushroom extracts --- p.60 / Chapter 3.2.1 --- ABTS + scavenging activity --- p.60 / Chapter 3.2.2 --- Hydroxyl radicals scavenging activity --- p.61 / Chapter 3.2.3 --- Hydrogen peroxide scavenging activity --- p.64 / Chapter 3.3 --- Total phenolic content --- p.67 / Chapter 3.4 --- Cytotoxicity of hydrogen peroxide --- p.69 / Chapter 3.4.1 --- "Colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay" --- p.71 / Chapter 3.4.2 --- Lactate dehydrogenase (LDH) assay --- p.72 / Chapter 3.4.3 --- Total cellular protein loss --- p.73 / Chapter 3.4.4 --- Residual hydrogen peroxide level --- p.76 / Chapter 3.4.5 --- Lipid peroxidation --- p.77 / Chapter 3.4.6 --- DNA damage --- p.79 / Chapter 3.5 --- Cytotoxicity of extracts --- p.85 / Chapter 3.6 --- Protection of H2()2-induced oxidative damage in HDFa cells --- p.88 / Chapter 3.6.1 --- Protective effect of mushroom water extracts --- p.88 / Chapter 3.6.2 --- Protective effect of CfAa on H2()2-incluced damage to HDFa --- p.93 / Chapter 3.6.3 --- Protective effect of CfAa on DNA damage in HDFa cells --- p.96 / Chapter 3.7 --- Modulation of cellular antioxidant defense system by CfAa --- p.99 / Chapter 3.7.1 --- Intracellular total glutathione --- p.100 / Chapter 3.7.2 --- Enzyme activities --- p.102 / Chapter 3.8 --- Speculation on the possible components in CfAa --- p.108 / Chapter Chapter 4 --- Conclusion and further works --- p.109 / References --- p.111

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Thesis (M.S.)--University of Michigan, 1991.

Made available in DSpace on 2014-06-11T19:24:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2005-08-03Bitstream added on 2014-06-13T20:31:52Z : No. of bitstreams: 1 camargo_sea_me_sjc.pdf: 698707 bytes, checksum: 21ecc468a433f0633cef989558394cc9 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Acredita-se que a penetração de peróxido de hidrogênio através do esmalte e dentina pode causar danos à polpa. A proposta deste trabalho foi avaliar a quantidade de peróxido de hidrogênio no interior da câmara pulpar de dentes bovinos e humanos com ou sem restauração, após clareamento pela técnica de consultório. Os dentes foram seccionados 3mm à junção amelo-cementária e divididos em dois grupos: A (setenta terceiros molares humanos) e B (setenta incisivos laterais bovinos) que foram subdivididos em: A1 e B1 restaurados com resina composta (Esthetic-X, Dentsply), A2 e B2 com CIV (Vidrion-R, SSWhite), A3 e B3 com CIV modificado por resina (CIV-MR) (Vitremer, 3M); A4, A5, B4 e B5 não foram restaurados. No interior da câmara pulpar de todos os dentes foi colocado tampão acetato. Os subgrupos A1 a A4 e B1 a B4 foram expostos ao peróxido de hidrogênio 38% (Opalescence XtraBoost, Ultradent) por 40 min. Os subgrupos A5 e B5 permaneceram em água deionizada por 40 min. O tampão acetato foi transferido a um tubo de ensaio reagindo com corante violeta leucocristal e peroxidase. A densidade óptica da solução foi avaliada em espectrofotômetro, os valores de absorbância convertidos em microgramas de peróxido e submetidos aos testes de Dunnett, Kruskal-Wallis, ANOVA e Tukey (5%). Verificou-se maior penetração de peróxido nos dentes bovinos (0,79l0,61æg) e humanos (2,27l0,41æg) restaurados com CIV-MR. A penetração do agente clareador foi maior em dentes humanos para qualquer situação experimental. Concluiu-se que a penetração de peróxido depende do material restaurador e que dentes humanos são mais susceptíveis à penetração do agente clareador para o interior da câmara pulpar do que dentes bovinos. / It is believe that externally applied bleachings agents could penetrate into the pulp chamber.This study was conducted to evaluate pulp chamber penetration of peroxide bleaching agent in human and bovine teeh, after office bleach technique. All the teeth were sectioned 3mm apical of the cemento-enamel junction and were divided into 2 groups: A (70 third human molars) and B (70 bovine lateral incisor) that were subdivided in: A1 and B1 restored using composite resin (Esthetic-X, Dentsply), A2 and B2 using glass ionomer cement (Vidrion-R, SSWhite), A3 and B3 using resin-modified glass ionomer cement (Vitremer, 3M); A4, A5, B4 and B5 were not restored. Acetate buffer was placed in the pulp chamber and the treatment agent was applied for 40 min as follow: A1 to A4 and B1 to B4 38% hydrogen peroxide exposure and A5 and B5 immersion into distilled water. The buffer solution was transferred to a glass tube where leuco crystal violet and horseradish peroxidase were added, producing a blue solution. The optical density of the blue solution was determined determined by spectrophotometer and converted into microgram equivalents of hydrogen peroxide. Data were submitted to ANOVA and Dunnett, Kruskal-Wallis, and Tukey tests (5%). A higher level of hydrogen peroxide penetrated into the pulp chamber in resin-modified glass ionomer cements groups, bovine (0,79l0,61æg) and human (2,27l0,41æg). The bleaching agent penetration was higher in human teeth for any experimental situation. The penetration of the hydrogen peroxide depend on restorative materials and that human teeth are more susceptible to penetration of bleaching agent into the pulp chamber than bovine teeth.

Existem muitas metodologias utilizadas para tentar analisar a permeação de peróxido de hidrogênio através das estruturas dentárias, porém não conseguem determinar o momento exato em que o peróxido começa a alcançar concentrações detectáveis dentro da câmara pulpar. OBJETIVO: Investigar a viabilidade de um modelo experimental de análise eletroquímica para detecção e mensuração da concentração de peróxido de hidrogênio proveniente de produtos utilizados em tratamento clareador e avaliar a cinética da difusão destes peróxidos através dos tecidos duros dentários. MATERIAIS E MÉTODOS: Foram utilizados 45 dentes incisivos bovinos permanentes mandibulares, cujo preparo envolveu a remoção da face lingual coronária, mantendo-se o esmalte e a dentina vestibulares intactos. Todos os dentes foram fixados em resina acrílica com auxílio de matriz elastomérica quadrangular e organizados segundo os testes: 1: análise eletroquímica e 2: análise espectrofotométrica. Para os testes foram utilizados clareadores à base de peróxido de hidrogênio (HP) e de peróxido de carbamida (CP) e seus respectivos placebos (PHP e PCP). Foram realizados três cronoamperogramas e três voltamogramas para cada uma das amostras. Utilizou-se a mesma cela no experimento eletroquímico e no teste espectrofotométrico, permitindo assim a comparação das metodologias. RESULTADOS: A análise eletroquímica mostrou na 1ª permeação de HP média de 1688,50 segundos quando comparada a 857,70s e a 457,70s da 2ª e da 3ª permeações, respectivamente. Desta forma observa-se que a 1ª permeação representa aproximadamente o dobro e o quadruplo dos valores sequenciais da 2ª e da 3ª permeações. Não foi detectado início de permeação para CP, PHP e PCP. Para o grupo HP há uma relação crescente nas concentrações de moléculas de peróxido de hidrogênio detectadas nas três permeações respectivamente. Entretanto, o crescimento entre a 1ª e 2ª permeação é discreto, quando comparado à 3ª permeação, onde foi detectada maior concentração de moléculas do peróxido de hidrogênio. No grupo CP observam-se médias de 2,96E-02 A na 1ª permeação, 3,11E-05 A na 2ª permeação e 1,37E-04 A na 3ª permeação, havendo diferença entre a 1ª e 3ª permeação (p = 0,00472). Todavia, não ocorreram diferenças entre os demais grupos (p > 0,05). Quando comparado o método eletroquímico e o método espectrofotométrico, o peróxido de hidrogênio (HP) não demonstrou diferença significativa entre as análises (p =0,0826); todavia o peróxido de carbamida mostrou diferenças entre as duas análises (p=0,0093). CONCLUSÕES: A metodologia eletroquímica é tão eficaz quanto à metodologia consolidada na literatura para a detecção da presença de peróxido de hidrogênio na câmara pulpar, nos testes com peróxido de hidrogênio 35%. O tempo necessário para que o peróxido de hidrogênio chegasse à câmara pulpar diminuiu a cada aplicação e a penetração do peróxido de hidrogênio aumentou a permeabilidade dos tecidos duros dentais. / There are many methods used to analyze the permeation of hydrogen peroxide through the tooth structure, but they cannot determine the exact moment when the peroxide begins to reach detectable concentrations within the pulp chamber. OBJECTIVE: To investigate the feasibility of an experimental model of electrochemical analysis for detection and measurement of the concentration of hydrogen peroxide from products used in bleaching and evaluate the kinetics of diffusion of these peroxides through dental hard tissues. MATERIALS AND METHODS: We used 45 bovine permanent mandibular incisors, whose preparation involved removing the lingual coronary hard tissues keeping intact the vestibular enamel and dentin. All teeth were fixed in acrylic resin with the aid of elastomeric matrix square and organized according to the tests: 1: electrochemical analysis and 2: spectrophotometric analysis. For tests were used based bleaching hydrogen peroxide (HP) and carbamide peroxide (CP) and their respective placebos (PHP and PCP). Three cronoamperograms and three voltammograms were performed for each sample. We used the same cell to the spectrophotometric test, thus allowing comparison of methodologies. RESULTS: The analysis showed the 1st electrochemical permeation HP average of 1688.50 seconds when compared to 857.70s and 457.70s of the 2nd and 3rd permeations respectively. Thus we observe that the 1st permeation is approximately double and quadruple sequential values of the 2nd and the 3rd permeations. Not detected early permeation for CP, PHP and PCP. For Group HP there is a ratio of molecules increasing concentrations of hydrogen peroxide detected in three permeations respectively. However, the growth between the 1st and 2nd permeation is understated when compared to 3rd permeation, where there has been a greater concentration of molecules of hydrogen peroxide. In the CP group were observed averages of 2.96 E-02A in the 1st permeation, 3.11 E-05 A in the 2nd permeation and 1.37 E-04 A in 3rd permeation, no difference between 1st and 3rd permeation (p = 0.00472) . However, there were no differences between the other groups (p> 0.05). When compared the electrochemical and spectrophotometric methods, hydrogen peroxide (HP) showed no significant difference between the analysis (p = 0.0826), yet the carbamide peroxide showed differences between the two analyzes (p = 0.0093). CONCLUSIONS: The electrochemical method is as effective as the consolidated methodology in the literature to detect the presence of hydrogen peroxide in the pulp chamber, in the tests with hydrogen peroxide 35%. The time required for the hydrogen peroxide to reach the pulp chamber decreased to each application and the penetration of hydrogen peroxide increased the permeability of dental hard tissues.

During the construction of the new urban area in the north-eastern part of Stockholm, Stockholm Royal Seaport, groundwater with extremely elevated levels of the carcinogenic aromatic hydrocarbon benzene was discovered in the area Hjorthagen. Such a contamination can be remediated in-situ by the use of chemical oxidation and biodegradation. Due to the fact that many factors such as contaminant composition, groundwater characteristics and temperature vary between sites, smaller bench scale studies are usually conducted before the full scale remediation on site. Little published research exists on the ability of these remediation techniques in areas with lower groundwater temperature such as Stockholm, why the need of a bench-scale study in this case is even larger. The objective of this master thesis is to, out of three investigated remediation agents, find the most suitable one for remediation of the benzene-contaminated groundwater in Hjorthagen. This was made in the form of a bench-scale study and the techniques studied were chemical oxidation, for which the two agents hydrogen peroxide (uncatalyzed and catalyzed in the form of Fenton’s reagent) and persulfate (activated with iron (II)) were used, and biological degradation by the use of a calcium peroxide-based compound. The study showed that the benzene-contaminated groundwater was best remediated with Fenton’s reagent, which was able to degrade the benzene with great success.