New trends in photobiology

Tuite, Eimer; Kelly, John M.

doi:10.1016/1011-1344(93)80173-7

Cited by 314 publications

(58 citation statements)

References 171 publications

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“…Several studies have reported that 1 O 2 preferentially induces piperidine-labile lesions at guanine residues (Ito et al, 1993;Tuite and Kelly, 1993;Kawanishi et al, 1986;Hall et al, 1998;Stevenson and Davies, 1999). NaN 3 , DABCO, methional, and methionine, which are potent and relatively specific scavengers of 1 O 2 , inhibited DNA damage by 100 mm homocysteine in the presence of Cu(II).…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, in the presence of catalase, this preference for cleavage at guanine residues displayed by 100 mm homocysteine was more pronounced (Figure 3d). Several studies have suggested that 1 O 2 is responsible for the induction of piperidine-labile lesions at most guanine residues (Kawanishi et al, 1986;Ito et al, 1993;Tuite and Kelly, 1993). -12), and 20 mm CuCl 2 in 10 mm phosphate buffer (pH 7.8) containing 5 mm DTPA were incubated at 371C for 120 min.…”

Section: Formation Of 8-oxodg In Human Cultured Cells By Homocysteinementioning

confidence: 99%

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Oxidative damage to cellular and isolated DNA by homocysteine: implications for carcinogenesis

2003

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Homocysteine is considered to be an important risk factor for cancer as well as cardiovascular diseases. To clarify whether homocysteine has potential carcinogenicity, we investigated formation of 8-oxo-7,8-dihydro-2 0 -deoxyguanosine (8-oxodG), which is known to be correlated with the incidence of cancer, induced by homocysteine in human cultured cell lines. Homocysteine increased the amount of 8-oxodG in human leukemia cell line HL-60, whereas the amount of 8-oxodG in its hydrogen peroxide (H 2 O 2 )-resistant clone HP100 was not increased. We investigated the mechanism for oxidative DNA damage by homocysteine using 32 P-labeled DNA fragments obtained from human tumor suppressor genes and a protooncogene. There were two mechanisms by which homocysteine caused DNA damage in the presence of Cu(II). A low concentration of homocysteine (20 lm) frequently induced piperidine-labile sites at thymine residues, whereas a high concentration of homocysteine (100 lm) resulted in damage principally to guanine residues. Catalase inhibited DNA damage by 20 lm homocysteine, indicating the participation of H 2 O 2 , but was ineffective in preventing DNA damage by 100 lm homocysteine. Experiments using a singlet oxygen probe showed that 100 lm homocysteine enhanced chemiluminescence intensity in deuterium oxide more than that in H 2 O. These results indicated that the metal-dependent DNA damage through H 2 O 2 is likely to be a more relevant mechanism for homocysteine carcinogenicity.

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Section: Discussionmentioning

confidence: 99%

Section: Formation Of 8-oxodg In Human Cultured Cells By Homocysteinementioning

confidence: 99%

Oxidative damage to cellular and isolated DNA by homocysteine: implications for carcinogenesis

2003

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“…Devido às suas propriedades fotoquímicas, têm sido desenvolvidos estudos visando sua aplicação na inativação de bacté-rias e vírus 4,5 , em células fotogalvânicas 6,7 e, mais recentemente, na preparação de eletrodos quimicamente modificados [8][9][10] .…”

Section: Introductionunclassified

Azul de metileno imobilizado na celulose/TiO2 e SiO2/TiO2: propriedades eletroquímicas e planejamento fatorial

Scotti¹,

Lima²,

Benvenutti³

et al. 2006

Quím. Nova

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Recebido em 10/12/04; aceito em 23/6/05; publicado na web em 20/1/06 METHYLENE BLUE IMMOBILIZED IN CELLULOSE/TiO 2 AND SiO 2 /TiO 2 : ELECTROCHEMICAL PROPERTIES AND FACTORIAL DESIGN. The electrochemical properties of methylene blue immobilized on cellulose/TiO 2 and mixed oxide SiO 2 / TiO 2 matrices were investigated by means of cyclic voltammetry. The electron mediator property of the methylene blue was optimized using a factorial design, consisting of four factors in two levels. The experimental observations and data analyses on the system indicate that the lowest peak separation occurs for Sil/TiOAM, 1.0 mol L -1 KCl solution and 20 mV s -1 scan rate, while values of current ratio closest to unity were found for Cel/TiOAM independent of electrolyte concentration, 0.2 or 1.0 mol L -1 , and scan rate, 20 mV s -1 or 60 mV s -1 .Keywords: factorial design; cyclic voltammetry; methylene blue. INTRODUÇÃOO azul de metileno é um corante orgânico redox fenotiazínico descoberto por Heinrich Caro em 1876, que inicialmente ganhou prestígio como corante citológico 1,2 e como indicador de óxido-redução 3 . Devido às suas propriedades fotoquímicas, têm sido desenvolvidos estudos visando sua aplicação na inativação de bacté-rias e vírus 4,5 , em células fotogalvânicas 6,7 e, mais recentemente, na preparação de eletrodos quimicamente modificados [8][9][10] .As propriedades eletroquímicas do corante são bem conhecidas em fase aquosa desde que seu potencial formal, E 0 , que se situa na faixa entre -0,1 e -0,4 V (vs. ECS) em soluções com pH entre 3 e 11 10 . Este potencial redox encontra-se muito próximo do potencial redox de várias espécies biomoleculares e eletrodos modificados quimicamente baseados no corante têm sido bastante utilizados como sistemas mediadores para acelerar processos de transferência de elétrons entre enzimas e superfícies de eletrodo 11 . Nos últimos anos, um considerável avanço foi observado na preparação de eletrodos quimicamente modificados, com destaque para os eletrodos de pasta de carbono devido à facilidade de construção, baixo custo, baixa corrente de fundo e possibilidade de incorporação de diferentes materiais [12][13][14] . Dentre estes materiais destacam-se matrizes inorgânicas, como sílica 15 , zeólitas 16 , argilas 17 , óxidos mistos obtidos pelo processo sol-gel 18 e matrizes orgânicas, como celulose 19 e derivados 20 , as quais conferem características especificas ao eletrodo 21 .Os materiais obtidos pelo processo sol-gel, tais como os óxi-dos mistos SiO 2 /M x O y , combinam as propriedades mecânicas da matriz de sílica com as propriedades químicas dos óxidos metáli-cos. O processo sol-gel permite obter um sólido com porosidade controlada, alta resistência mecânica e química, além de se ter o óxido metálico altamente disperso na matriz de sílica. Estas características permitem que uma maior concentração de mediador seja incorporada no eletrodo 22 .A celulose é um biopolímero relativamente inerte, que apresenta algumas vantagens tais como baixo custo, razoável porosidade, facilidade de ma...

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“…Nogalamycin or adriamycin as anticancer drugs, and ethidium bromide or methylene blue as fluorescence DNA detecting reagents are included in this category. 5,14 Especially, nogalamycin is known to bind to DNA duplex with a unique intercalation mode, which is called "threading intercalation," since its two substituents are projecting out of both grooves of DNA duplex. 15 One of the substituents of such threading intercalator needs to go through or thread into the adjacent base pairs to form a threading intercalation complex.…”

Section: Pseudo-catenane Formation Between Dna Duplex and Threading Imentioning

confidence: 99%

Electrochemical DNA Detection Using Supramolecular Interactions

Sato

Takenaka

2012

ANAL. SCI.

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New trends in photobiology

Cited by 314 publications

References 171 publications

Oxidative damage to cellular and isolated DNA by homocysteine: implications for carcinogenesis

Oxidative damage to cellular and isolated DNA by homocysteine: implications for carcinogenesis

Azul de metileno imobilizado na celulose/TiO2 e SiO2/TiO2: propriedades eletroquímicas e planejamento fatorial

Electrochemical DNA Detection Using Supramolecular Interactions

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