ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1993.tb02278.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe extensive use of bergamot oil in perfumery and cosmetics led us to study the photoreactivity of 5‐geranoxypsoralen (bergamottin), the major chromophore in this oil. Structure determination of the bergamottin photoproducts was achieved using extensive NMR techniques including two‐dimensional NMR:1H‐13C correlation by long‐range coupling,1H‐1H correlation spectroscopy (COSY) and1H‐1H COSY phase sensitive (COSYPH). Bergaptol is formed according to the well‐known fragmentation of allyl‐aryl ethers. The other photoproducts arise from an intramolecular [2 + 2] photocycloaddition and appeared as an equimolecular mixture of diastereomeric cyclobutyl derivatives. The relative configurations were determined by nuclear Overhauser effect analysis. These structures were further corroborated by X‐ray crystal analysis. The facile formation of an intramolecular cyclobutyl derivative in bergamottin might prevent the intermolecular cyclobutane adduct formation with pyrimidine DNA bases responsible, in part, for phototoxi

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1993.tb02279.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractAbsorption, fluorescence and resonance Raman spectra of the membrane dye merocyanine‐540 (MC540) were measured. The aggregation of the dye, its binding to lipid membranes and its response to crossmembrane electric potential differences were studied. The dye was found to aggregate even at micromolar concentrations in water, but not in organic solvents. The dimerization constant was evaluated by spectroscopic techniques. The binding constant to liposomes was estimated by a spectroscopic titration method. Resonance Raman spectra of MC540 were measured for the first time. Distinct changes were observed in the vibrational spectrum upon the generation of a valinomycin‐induced K+diffusion potential (Nernst potential) on liposomes. The ratio of Raman band intensities, which was found to be related to the membrane potential, can be used to evaluate the absolute value of the electric potent

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1993.tb02280.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractFluorescence line narrowing (FLN) spectroscopy was used to study the vibrational features of Zn porphyrins, including Zn octaethylporphine, Zn mesoporphyrin, Zn deuteroporphyrin and Zn coproporphyrin, and the interaction of these porphyrins with their solvent matrices. A number of ground‐state vibrational levels were identified for each of the Zn porphyrins. Six of these levels persistent throughout almost all spectra were analyzed in terms ofcontributions of specific internal vibrational modes of the porphyrins. A number of other vibrational levels were identified as characteristic of the peripheral substituents of Zn porphyrin. Phonon wing contribution in the FLN spectra increased with increased polarity of the solvent matrix, and the Stokes shift calculated from the conventional spectra was correlated with the strength of phonon coupling. Specific vibrational modes were found to couple differently with the solvent and to have different phonon wings. The conventional and energy‐selected spectra of Zn coproporphyrin in 5Mguanidine HCI suggest that guanidine ligates to the Zn a

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1993.tb02281.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractSix new aluminum and silicon phthalocyanines have been synthesized and their photocytotoxicity toward V79 cells has been studied. The compounds that have been prepared are: AIPcOSi(CH3)2(CH2),N(CH3)2, I; AIPcOSi(CH3)2(CH2)3N(CH3)3+I−, II; CH3SiPcOSi(CH3)2(CH2)3N(CH3)2, III; HOSiPcOSi(CH3)2(CH2)3N(CH3)2, IV; HOSiPcOSi(CH3)2(CH2)3)3(CH3)3+I−, V; and SiPc[OSi(CH3)2(CH2)3N(CH3)3+I−]2, VI. Relative growth delay values for compounds I‐VI and relative cytotoxicity values for compounds I, II, IV, V and VI have been determined. Compounds I and II have been shown to be comparable in photocytotoxicity to what is presumed to be AIPcOH.xH2O, and compound IV has been shown to have greater activity. The classes of compounds to which these six compounds belong appear to have potential for photodynamic

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1993.tb02282.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractMammalian cells attached to membrane filters or deposited on filters without attachment were exposed to gas‐phase singlet oxygen (1O2) in the absence of any other reactants. Cells were exposed in a monolayer or less, in the absence of external medium, during steady‐state1O2generation, ensuring that singlet oxygen impinged directly and equally on all cells simultaneously. The current methodology for cell exposure ensures that1O2is initially the only reactive species to which the cells are exposed. Results seen with this system can therefore be attributed solely and unambiguously to events initiated by1O2. Further, all cells in the sample receive the same magnitude of exposure per surface area per time interval, which supports calculations of the amount of1O2required for irreversible cell damage, based on measured1O2flux and exposed cell surface area. Exposure to pure1O2irreversibly damaged a variety of cell types, including rat basophilic leukemia, human squamous carcinoma and Chinese hamster lung fibroblast cell lines, and murine primary hepatocytes. Cell survival curves following exposure to1O2followed apparent first‐order kinetics. A large number of singlet oxygen collisions (˜ 1012‐1013) were required to inactivate a cell, on average, indicating a low probability that singlet oxygen collision will reduce cell survival. Regardless of cell type or the survival endpoint measured, lethal toxicity required a fairly constant number of1O2collisions per cell. This poses a seriouscaveatin the assignment of causality in correlating1O2‐initiated cellular damage with mechanism of death,i.e.most damage observed will not be related to death. The importance of various toxic effects of1O2, whether lethal or nonlethal, will depend on the magnitude of exposure and therefore on the context in which expos

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1993.tb02283.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractThe nucleoside 4‐thiouridine, present in some bacterial tRNA species, is known to be a chromophore and a target for near‐UV light‐induced growth delay and also mediates both photoprotection and near‐UV cell killing in various bacterial strains. To investigate the photoreaction of 4‐thiouridine with DNA or its precursors, we irradiated aqueous mixtures of thymine and 4‐thiouridine with 334 nm light and then separated photoproducts using two or more stages of reversed‐phase high performance liquid chromatography. The two equally abundant major photoproducts were analyzed by UV absorbance spectrophotometry, fast‐atom bombardment and electron‐impact mass spectrometry, and1H‐ and13C‐NMR spectroscopy, and have been identified as two diastereomers of 6‐hydroxy‐5‐[1‐(β‐D‐erythro‐pentofuranosyl)‐4′‐pyrimidin‐2′‐one]dihydrothymine (o6hThy[5‐4]Pdo), of molecular weight = 370.32. These two diastereomers, although stable at room temperature or below, are interconvertible by heating (90d̀C for 5 min) in aqueous solution. The possible biological significance of this photoproduct is discussed, and an application as a crosslinker for oligonucleo

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1993.tb02284.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractExposure of mice to UV radiation inhibits the induction and elicitation of the delayed‐type hypersensitivity (DTH) response toCandida albicans. To determine whether UV irradiation also affects the pathogenesis of systemicC. albicansinfection, C3H mice were exposed to a single dose of 48 kJ/m2UV‐B radiation from FS40 sunlamps 5 days before or 5 days after sensitization with formalin‐fixedC. albicansand challenged intravenously (i.v.) with a lethal dose of viable fungi 6 days after sensitization (11 or 1 days after UV irradiation). Exposing unsensitized mice to UV radiation 11 days before lethal challenge had no effect on survival, but the survival time of mice exposed to UV radiation 1 day before challenge was reduced by more than 50%. In the latter group, decreased survival time correlated with persistence ofC. albicansin the brain and progressive growth ofC. albicansin the kidneys. Sensitization of unirradiated mice with formalin‐fixedC. albicansextended their survival time following lethal i.v. challenge with viableC. albicans. Exposing the mice to UV radiation 5 days before sensitization did not abrogate this beneficial effect of sensitization on survival, even though it significantly reduced the DTH response. Thus, immunity to systemic infection did not depend on the ability of the mice to exhibit a DTH response toC. albicans. The beneficial effect of sensitization on survival after lethal infection was abrogated, however, in mice exposed to UV radiation 1 day before lethal challenge withC. albicans. Furthermore, these mice were unable to contain the progressive growth of C. albicuns in the kidneys, in contrast to sensitized, unirradiated mice. The induction of cutaneous inflammation with turpentine had no effect on the survival rate of mice lethally infected withC. albicans, suggesting that inflammation alone is not sufficient to decrease the survival time ofC. albicans‐infe

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1993.tb02285.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractReplicate cultures of the yeast,Saccharomyces cerevisiaewere irradiated with 632.8 nm coherent light from He‐Ne lasers at irradiances of 6.5 times 1015and 1.0 times 1016photons s−1cm−2. Irradiation periods ranged from 0 to 652 min, and cultures were grown until well into the exponential phase. Unirradiated control cultures were grown alongside the irradiated cultures under otherwise identical conditions. The extents of growth in the control and irradiated cultures were compared spectrophotometrically at the end of each experiment. contrary to the expectations of Karuet al. (e.g.Karu, 1988,Lasers Life Sci.2, 53–74) no growth enhancement was found in the irradiated cultures, but a mild inhibitory effect was o

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1993.tb02286.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

AbstractPrevious studies have shown that natural killer (NK) cell activity was suppressed in volunteer subjects exposed to ultraviolet radiation (UVR) from solarium lamps. The present studies were carried out to determine that spectrum of UVR responsible for suppression of NK activity and to developin vitromethods to analyze the effectivenes of sunscreen agents in prevention of UVR‐mediated suppression of NK activity and other aspects of immune function. UVR from a xenon are lamp source was used to irradiate peripheral blood lymphocytes (PBL) in wells of tissue culture flasks, and transmission interference filters were used to eliminate UVR of particular wavelengths. The results indicated that UVR from this source inhibited NK activity of PBL in a dose‐dependent manner with a 50% inhibitory dose of 5.5 mJ/cm2when unfiltered and 29.6 mJ/cm2when diluted through cellulose acetate, which gave a UV spectrum similar to that in solar radiation. Equivalent suppression of NK activity was mediated by UV‐A (UVR>315 nm) at dose levels of 4.2 J/cm2, which was approximately 140 times greater than the amount of UV‐B (UVR>315 nm) needed to suppress NK activity. Similar dose‐response curves were seen for inhibition of mitogenic responses to phytohemagglutinin except that the latter appeared less sensitive than NK to inhibition by UV‐A. These studies suggest that whe the greater proportion of UV‐A in solar radiation adn its greater penetration into skin is taken into account, UV‐A may have equivalent or greater direct immunosuppressive effects than UV‐B. The mechanisms of their immunosuppressive effects may, however, differ. Thein vitrosystem described here would appear to provide a simple test system for further analysis of UVR‐indu

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1993.tb02287.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY