摘要:

AbstractA simple, well characterized porphyrin dimer with ether linkage was synthesized from 2‐ (1‐hydroxyethyl)deuteroporphyrin dimethyl ester and found to be an effective in vivo photosensitizer in the murine SMT‐F tumor system. The structure of the pure dimer was confirmed by NMR and mass spectro

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb01658.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe photoinduced exchange reactions of cytosine (la) and 5‐methylcytosine (IIa) with two primary amines have been studied. The reactions ofIaandIIawith methylamine lead, respectively, to 1‐methylcytosine (Ib) and 1,5‐dimethylcytosine (IIb) as final products; the reactions of the same two starting materials withn‐butylamine gives the correspondingn‐butyl compounds. The reactions ofIIawith the two amines also gave small amounts of 1‐methylthymine and 1‐n‐butylthymine. An opened ring intermediate, N‐(N'‐methylcarbamoyl)‐3‐arnino‐2‐methylacrylamidine (IVa), was isolated from theIIa‐methylamine system irradiated at pH 7 and shown to be a precursor of bothIIband 1‐methylthymine. The pH profiles for rate of production ofIIb, 1‐methylthymine andIVain the reaction ofIIawith methylamine were determined and found to be similar in shape. All three profiles show a maximum in reactivity at about pH 8.7 with some reactivity being de

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb01659.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—The quantitation of porphyrin and its photoproducts in biological samples is important in diverse applications including, but not limited to, tumor phototherapy. Differences in fluorescence properties, e.g., emission spectra and lifetimes, of the various components can be utilized to resolve the individual contributions. In this report time‐resolved measurements using multifrequency phase and modulation rluorometry are employed to study mixtures of protoporphyrin IX and photoprotopor‐phyrin. Individual lifetimes of 14.85 ns and 5.95 ns were determined for dioxane solutions of protoporphyrin IX and photoprotoporphyrin, respectively. These lifetime values were utilized to resolve the individual emission spectrum of each component in the mixture using the phase‐resolved Huorometry te

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb01660.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

Abstract—The nitrobiphenyl ether herbicides; 4‐nitrobiphenyl ether, bifenox, nitrofen, acifluorfen, acifluorfen‐methyl, acifluorfen‐ethyl, and oxyfluorfen were reduced to their corresponding nitro radical anions by visible light in the presence of β‐carotene, lycopene, retinol, retinal, retinoic acid and retinyl acetate in anaerobic solutions at high pH. It was more difficult to obtain spectra of bifenox, nitrofen and oxyfluorfen than acifluorfen derivatives, probably due to their poor solubilities. In neutral solutions the steady‐state concentration of the nitro radical anions was low due to their faster rate of dispropor‐tionation and the poor solubility of β‐carotene. In the presence of retinal, the nitro radical anion of acifluorfen was produced at pH 7.4. Compounds containing conjugated double bonds such as crotonaldehyde and 2.4‐hexadienal also reduced acifluorfen and its derivatives to their respective nitro radical anions in the presence of light. Ubiquinone‐50 which does not contain conjugated double bonds in the side chain did not reduce acifluorfen und

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb01661.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractMicelles formed by sodium taurocholate (NaTC) and mixed micelles formed by NaTC with detergents (SDS, reduced Triton X‐100 and CTAC) were studied with fluorescent probes. Pyrene was used as an indicator of the polarity of the micellar binding site by comparison of the fluorescence spectra and vibronic band intensity ratios of pyrene in the different systems. Perylene was used as a fluorescence polarization probe to study the rigidity of the NaTC and mixed micelles. The fluorescence lifetime of perylene in the different systems was also measured. Results of the studies were compared with measurements of the probes in cyclohexane, ethanol and aqueous beta‐cyclodextrin. Perylene was found to be more rigidly bound in the NaTC micelles than in the detergent micelles. Insertion of small amounts of reduced Triton X‐100 into the NaTC micelles appears to increase the rigidity. The binding sites of NaTC and CTAC have similar polarities, and are more polar than those of SDS and reduced Triton X‐100. Insertion of any of the detergents into the NaTC micelle decreases the polarity of the binding site, possibly by reducing the penetration of water into the

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb01662.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA chemical method for the identification and the quantitative detection of psoralen DNA furan‐side photoadducts formed in cells is presented. It is based on an enzymatic digestion of the purified DNA extracted from the treated cells and a further separation by high performance liquid chromatography of the modified nucleosides coupled to a highly sensitive fluorescence analysis and detection. Using this method, 3‐carbethoxypsoralen‐ DNA photoadducts formed in yeast and mammalian cells have been identified and quantified. The predominant photoadducts induced have been identified as twocis‐syndThd(564'5')3‐CPs diastereoisomers. In Chinese Hamster V79 cells treated with 3‐carbethoxypsoralen at 50 μM and irradiated at 365 nm with an incident dose of 24 kJ/m2, the two monoadducts could be quantitatively assessed at levels as low as 1.3 and 0.7 per 10 00

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb01663.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractMonochromatic 334‐nm radiation delivered under aerobic conditions inactivates the genetic activity (ability to transform auxotrophic recipient cells to nutritional prototrophy) of isolated transformingBacillus subtilisDNA. The presence of superoxide dismutase (SOD), catalase, and mannitol reduces the 334‐nm inactivation. The rate of inactivation of the genetic activity by 334‐nm radiation is enhanced fivefold by the sensitizer 2‐thiouracil (s2Ura). This enhancement is substantially reversed when the irradiations are performed in the presence of mannitol, and, to a lesser extent, SOD. Catalase slightly reduces the s2Ura enhancement of 334‐nm inactivation of transforming activity. Backbone breaks induced in the same DNA by aerobic 334‐nm radiation were also enhanced markedly by the presence of s2Ura; this enhancement was reversed by the presence of mannitol and, to a lesser extent, SOD during irradiation. Catalase had no effect upon s2Ura‐enhanced, 334‐nm‐induced SSBs. Whereas DNA breakage may be responsible for a portion of the inactivation of the DNA by the photosensitized reaction between s2‐Ura and 334‐nm radiation, it is not the only inactivating lesion, because the yield of SSBs per lethal hit per unit length of DNA is not constant for all the irradiation conditions studied. The results support a complex role for active oxygen species in inactivation of transforming activity and DNA breakage by s2Ura‐enhanced 334‐nm radiation. They are also consistent with the formation of superoxide anion, hydroxyl radical, and possibly also singlet molecular oxygen, generated from ground‐state molecular oxygen by reactive s2Ura in b

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb01664.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractRelative to their L5178Y‐S counterparts, L5178Y‐R cells have an impaired capacity to form patches in DNA after exposure to UVC radiation. The photolysis of 5'‐bromodeoxyuridine (BrdUrd) incorporated into DNA was used to estimate the number of 'repair patches'formed in response to a 254 nm UV (UVC) exposure. L5178Y‐S cells, typical of rodent cell lines, formed a small number of patches in exposed DNA (1‐2 patches per 1 times 108dalton during a 6 h recovery after an exposure of 20 J/m2). In contrast, DNA extracted from L5178Y‐R cells exposed to UVC and subsequently incubated with BrdUrd for 6 h showed no evidence of BrdUrd incorporation indicating no capacity to form sites of repair (fewer than 0.5 sites of BrdUrd incorporation per 1 times 108dalton). Moreover, in L5178Y‐R cells high fluences of UVC caused an extensive DNA degradation. Such degradation was not observed in L5178Y‐S cells during the 24‐h post‐exposure period. These results are consistent with the notion that L5178Y‐R cells have a reduced capacity to repair DNA damage ind

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb01665.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractAmelioration of dihematoporphyrin ether (DHE) induced skin photosensitivity by medications either suspected or known to influence porphyrin metabolism or inflammatory response was evaluated in 357 female athymic NCR‐nude mice (308 study animals, 49 controls) in 56 separate study groups. Seventy‐two hours after injection with 25 mg/kg of DHE, the study animals'abdomens were irradiated with 4.125‐4.25 J/cm2of visible light. Controls were irradiated after receiving either medication, solubilizing agent, or no injection. The abdominal surface burns were examined daily and graded as extensive, partial, or no burn. Statistical comparison was made between irradiated mice injected with DHE only and irradiated mice injected with DHE and medication. Injection of medications which influenced metabolism (hydroxychloroquine, hydrochlorothiazide) produced fewer extensive (P<0.01) but greater frequencies of partial burns than DHE controls. Medications which block histamine effect (cimetidine and/or hydroxyzine) resulted in fewer extensive (P<0.03) and roughly equal frequencies of partial burns compared with DHE controls. Steroids (dexamethasone, methylpred‐nisolone, triamcinolone) which interfere with inflammatory response resulted in similar extensive and partial burn levels. Control animals receiving only medication, solubilizing agent, or no injection had no photosensitivity and consequently showed no burns. The results from this study suggest that inhibition of histamine effect and, to a lesser extent, increased activity of porphyrin catabolic pathways may decrease skin photosensitivity associated with DHE adminis

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb01666.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe long wavelength UV‐induced photoisomerization of retinoic acid has been investigated in physiologic‐like solutions. By high‐performance liquid chromatographic analysis seven isomers of the parent molecule were observed at the photostationary state. The structures of these isomers have been determined using high‐field nuclear magnetic resonance spectroscopy. While addition of a non‐ionic detergent had no effect on the retinoic acid photoisomerization, a number of proteins, as well as a phospholipid, completely inhibited this process. Possible reasons for differences in observed isomer distribution relative to earlier studies, as well as for the effects of the photoprotectant compounds, are

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1988.tb01667.x

出版商:Blackwell Publishing Ltd    

年代:1988

数据来源: WILEY