bluuebunny/crossref_metadata_2025_split huggingface dataset:
TIME‐RESOLVED LUMINESCENCE SPECTROSCOPY OF PHOTOSENSITIZERS OF BIOMEDICAL INTEREST*
Authors: Andreoni Alessandra 
Published: January 2008

Abstract—Studying the fluorescence decay of chromophores, either used as fluorescent labels to stain specific biomolecules or as photosensitizers to produce irreversible chemical or physicochemical modifications on biological substrates, is being demonstrated to be a valuable method of investigating the interactions underlying a variety of phenomena. In fact, all possible primary steps in a photosensitized biological system are phenomena that may occur during the chromophore S, lifetime and act as quenching mechanisms of the S, state. Thus they can be identified, and the relative importance of the corresponding transient species quantitatively determined, with suitable techniques of time‐resolved fluorescence spectroscopy. The examples discussed in this paper concern both tumor photosensitizing drugs, such as anthracyclines and porphyrins, and skin sensitizers (e.g. furocoumarins).
ACTIVITY AND PHYSICOCHEMICAL PROPERTIES OF PHOTOFRIN®
Authors: Ho Yau‐Kwan , Missert Joseph R. , Dougherty Thomas J. 
Published: January 2008

AbstractUpon certain conditions of storage, Photofrin® samples changed their photodynamic therapy activity in mice. These samples showed similar absorption and high performance liquid chromatography (HPLC) profiles. The Photofrin® samples that were active, however, had higher relative fluorescence yields than those which failed. Active and inactive samples also had different characteristics when analyzed by gel filtration chromatography using Sephacryl S‐300; the failed samples had 60% or more high‐molecular‐weight fraction. The change of the amount of this high‐molecular‐weight fraction with the time of storage at room temperature could be clearly demonstrated. Results from fluorescence, HPLC and mass spectrometry studies suggest that the high‐molecular‐weight fraction may form by dehydration from or condensation between various components of Photofrin®.
CAROTENOIDS OF Erwinia herbicola AND AN Escherichia coli HB101 STRAIN CARRYING THE Erwinia herbicola CAROTENOID GENE CLUSTER
Authors: Hundle Bhupinder S. , Beyer Peter , Kleinig Hans , Englert Gerhard , Hearst John E. 
Published: January 2008

AbstractCarotenoid pigments of Erwinia herbicola and a transformed strain of Escherichia coli carrying the carotenoid biosynthesis gene cluster of E. herbicola have been analyzed. Both organisms are capable of making essentially the same carotenoids, indicating that all of the genes required for the biosynthesis of the wild type E. herbicola carotenoids have been transformed intact into E. coli. The major products in both species of bacteria are p‐cryptoxanthin glucoside, zeaxanthin monoglucoside and zeaxanthin diglucoside. These compounds are the first example of secondary, non‐allylic carotenoid glucosides. The absolute configuration 3R,3′R for zeaxanthin diglucoside was determined from its circular dichroism spectrum. Both species of bacteria also accumulate small amounts of hydrocarbon carotenes with similar cisltrans isomerization states.
PHOTOINITIATED VECTORIAL TRANSMEMBRANE ELECTRON TRANSFER IN BILAYERS SENSITIZED BY A FACE TO FACE TRIPORPHYRIN ACTING AS A MOLECULAR ELECTRONIC DEVICE. AMPLIFICATION DUE TO IONIC COUPLING
Authors: Lamrabte A. , Janot J. M. , Bienvenue E. , Momenteau M. , Seta P. 
Published: January 2008

AbstractUnder light excitation transmembrane electron transfer is observed when a stacked Zn‐Cu‐Zn triporphyrin is incorporated in a bilayer between aqueous redox phases. The electric polarization of the membrane due to the photoinduced transmembrane charge flux drives ion transport. This effect increases the net charge transfer across the system, giving rise to an amplification similar to a field effect transistor. Thus this system can be considered an organic photo transistor.
ON THE EVIDENCE FROM HIGH‐INTENSITY TWO‐PHOTON LASER PHOTOLYSIS FOR ENERGY TRANSFER FROM HIGH‐LYING QUASI‐RYDBERG STATES OF THYMINE TO ISO‐ENERGETIC STATES OF WATER
Authors: Daniels Malcolm 
Published: January 2008

AbstractHigh intensity two‐photon picosecond excitation at 266 nm (effective energy 9.2 eV) has been shown to cause efficient photolysis of thymine in aqueous solution. Experimental results for the quantum yield of solvated electrons, θ (e−aq), and the net consumption of thymine, θ(‐Thy) have been interpreted (Oraevsky and Nikogosyan, 1985) as indicating a stoichiometric excess of solvated electrons over thymine radical‐cations. To account for this under conditions in which direct two‐photon photolysis of water is negligible, it has been concluded that it is necessary to postulate the occurrence of extensive energy transfer from high‐lying thymine states to dissociating/ionizing states of water. This Note demonstrates that: (i) the supposed excess of e−aqdepends on an implicit assumption concerning the secondary radical reactions (dimerization) such that ‐ΔTh+=ΔThy+; if secondary radicals dismutate then ‐Thy =½δThy+, leading a stoichiometric deficit of e−aq; and (ii) the experimental results can be accounted for by a mixed dimerization/dismutation mechanism, without invoking energy transfer. Thus there is no evidence unambiguously requiring the postulate of energy transfer. But if it occurs, stoichiometry places restrictions on the extent of transfer and the nature of the secondary radical reactions.
THE INFLUENCE OF SMECTIC PHASES OF PERFLUORODECYL DECANE ON THE PHOTOREACTIONS OF PERFLUOROHEPTYL OCTYL KETONE. AN EXAMPLE OF MICROSCOPIC DISORDER IN HIGHLY ORDERED LAYERED PHASES*
Authors: Vilalta Patricia M. , Hammond George S. , Weiss Richard G. 
Published: January 2008

AbstractThe consequences of solvent order, imposed by the two smectic phases of 1,1,1,2,2,3,3,4, 4,5,5,6,6,7,7,8,8,9,9,10,10‐heneicosylfluoroeicosane (F10H10, a “diblock” molecule) on the photochemistry of 1,1,1,2,2,3,3,4,4,5,5.6,6,7,7‐pentadecylfluoro‐8‐hexadecanone (F7COH8) were investigated. Results from irradiations of F7COH8 in smectic F10H10 are compared to those obtained in hexane, perfluorohexane, and the isotropic phase of F10H10. They are complemented by 2H‐NMR experiments on F10H10 solutions of F7COH8 deuterated at the methylene alpha to the carbonyl, and differential scanning calorimetry thermograms. More than 85% of the photoproducts are derived from carbonyl reduction and Norrish II processes. Based upon the 2H‐NMR spectra and Norrish II photoproduct ratios, the microscopic environment experienced by the locus of reaction of F7COH8 in smectic F10H10 is not very restrictive towards the solute shape changes that must occur. This conclusion was not anticipated because the macroscopic order of the smectic phases of F10H10 is high.
REPAIR OF NEAR‐VISIBLE‐ and BLUE‐LIGHT‐INDUCED DNA SINGLE‐STRAND BREAKS BY THE CHO CELL LINES AA8 and EM9
Authors: Churchill Mark E. , Peak Jennifer G. , Peak Meyrick J. 
Published: January 2008

AbstractThe induction of single‐strand breaks (SSB) and the kinetics of SSB repair were measured in two Chinese hamster ovary cell lines irradiated with monochromatic photons of near‐visible radiation (405 nm) and blue light (434 nm). The radiosensitive and UV‐A‐sensitive mutant line EM9 is known to repair SSB induced by ionizing radiation or 365‐nm UV‐A more slowly than the parent line AA8. At the 10% survival level, EM9 cells were 1.7‐ and 1.6‐fold more sensitive than AA8 cells to 405 and 434 nm radiation, respectively. This sensitivity was not due to differences in induction of SSB because AA8 and EM9 cells accumulated the same number of initial breaks when irradiated at 0.5°C with either 405 nm (5.9 SSB per MJ/m2) or 434 nm (5.1 SSB per MJ/m2), as measured by alkaline elution. When the cells repaired these SSB at 37°C in full culture medium, biphasic repair kinetics were observed for both cell lines. In both phases of repair, EM9 cells repaired breaks induced by both wavelengths more slowly than did AA8 cells. The 1½ values for the repair phases for 405‐nm‐induced SSB were 3.8 and 150 min for EM9, and 1.5 and 52 min for AA8; the corresponding values for repair of 434 nm breaks were 3.7 and 39 min for EM9, and 2.0 and 30 min for AA8. Because of this slower repair, EM9 cells left more SSB unrepaired after 90 min than did AA8 cells for both wavelengths. The ratio of unrepaired breaks in EM9 cells to that in AA8 cells was 1.4 and 1.7 times higher for 405 and 434 nm radiation, respectively. Thus, the sensitivity of EM9 cells to near‐visible and visible light correlates with a deficiency in repairing SSB induced by these wavelengths. These results suggest that DNA damage may be a critical event in visible‐light‐induced cellular lethality and that an important determinant of the ability of AA8 and EM9 cells to survive visible light irradiation may be their ability to repair DNA strand breaks.
INACTIVATION ACTION SPECTRA OF BACILLUS SUBTILIS SPORES IN EXTENDED ULTRAVIOLET WAVELENGTHS (50–300nm) OBTAINED WITH SYNCHROTRON RADIATION
Authors: Munakata Nobuo , Saito Mikio , Hieda Kotaro 
Published: January 2008

AbstractFive types of Bacillus subtilis spores (UVR, UVS, UVP, RCE, and RCF) differing in repair and/or recombinational capabilities were exposed to monochromatic radiations at 13 wavelengths from 50 to 300 nm in vacuum. An improved biological irradiation system connected to a synchrotron radiation source was used to produce monochromatic UV radiation in this extended wavelength range with sufficient fluence to inactivate bacterial spores. From the survival curves obtained, the action spectra for the inactivation of the spores were depicted. Recombination‐deficient RCE (recE) and RCF (recF) spores were more sensitive than the wild‐type UVR spores in the entire range of wavelengths. This was considered to mean that DNA was the major target for the inactivation of the spores. Vacuum‐UV radiations of125–175 nm were effective in killing the spores, and distinct peaks of the sensitivity were seen with all types of the spores. Insensitivities at 190 and 100 nm were common to all five types of spores, indicating that these wavelengths were particularly impenetrant and absorbed by the outer layer materials. The vacuum‐UV peaks centering at 150 nm were prominent in the spores defective in recombinational repair, while the far‐UV peaks at around 235 and 270 nm were prominent in the UVS (uvrA ssp) and UVP (uvrA ssp polA) spores deficient in removal mechanisms of spore photoproducts. Thus, the profiles of the action spectra were explained by three factors; the penetration depth of each radiation in a spore, the efficiency of producing DNA damage that could cause inactivation, and the repair capacity of each type of spore.
SULFONATED PHTHALIMIDOMETHYL ALUMINUM PHTHALOCYANINE: THE EFFECT OF HYDROPHOBIC SUBSTITUENTS ON THEin vitroPHOTOTOXICITY OF PHTHALOCYANINES
Authors: PAQUETTE BENOIT , BOYLE ROSS W. , ALI HASRAT , MACLENNAN ALEXANDER H. , TRUSCOTT T. GEORGE , VAN LIER JOHAN E. 
Published: January 2008

Abstract—The photocytotoxicity of sulfonated phthalimidomethyl aluminum phthalocyanine, a more hydrophobic photosensitizer as compared to phthalocyanine substituted with sulfonate groups only, was investigated. Inclusion of 1–2 phthalimidomethyl groups into disulfonated aluminum phthalocyanine, resulted in increased partition coefficients betweenn‐octanol and water, and a six‐fold increase in both cellular uptake and photocytotoxicity towards Chinese hamster lung fibroblast cells (line V‐79). Reducing the number of phthalimidomethyl groups, or increasing the degree of sulfonation, lead to a decrease in the partition coefficient, cellular uptake, and phototoxicity. The quantum yield of singlet oxygen was comparable for all dyes tested in this series, indicating that no significant change in this photophysical parameter resulted from phthalimidomethylation. These results suggest that the addition of 1–2 phthalimidomethyl groups to disulfonated aluminum phthalocyanine improves cellular uptake, but, as the relative efficiency of cell killing was not effected, the intracellular distribution on photosensitive molecules may not be modified.
RESONANCE RAMAN SPECTRA OF BACTERIORHODOPSIN MUTANTS WITH SUBSTITUTIONS AT ASP‐85, ASP‐96, AND ARG‐82
Authors: LIN STEVEN W. , FODOR STEPHEN P. A. , MIERCKE LARRY J. W. , SHAND RICHARD F. , BETLACH MARY C. , STROUD ROBERT M. , MATHIES RICHARD A. 
Published: January 2008

Abstract—Detergent solubilized bacteriorhodopsin (BR) proteins which contain alterations made by site‐directed mutagenesis (Asp‐96→Asn, D96N; Asp‐85→Asn, D85N; and Arg‐82→Gln, R82Q) have been studied with resonance Raman spectroscopy. Raman spectra of the light‐adapted (BRLA) and M species in D96N are identical to those of native BR, indicating that this residue is not located near the chromophore. The BRLA states of D85N and especially R82Q contain more of the 13‐cis, C=N syn (BR555) species under ambient illumination compared to solubilized native BR. Replacement of Asp‐85 with Asn causes a 25 nm red‐shift of the absorption maximum and a frequency decrease in both the ethylenic (‐7 cm−1) and the Schiff base C=NH+ (‐3 cm−1) stretching modes of BRLA. These changes indicate that Asp‐85 is located close to the protonated retinal Schiff base. The BRLA spectrum of R82Q exhibits a slight perturbation of the C=NH+ band, but its M spectrum is unperturbed. The Raman spectra and the absorption properties of D85N and R82Q suggest that the protein counterion environment involves the residues Asp‐85−, Arg‐82+ and presumably Asp‐212−. These data are consistent with a model where the strength of the protein‐chromophore interaction and hence the absorption maximum depends on the overall charge of the Schiff base counterion environment.
ELECTROSTATIC EFFECTS IN THE PHOTOREDUCTION OF FLAVINS BY EDTA
Authors: MOORE WILLIAM M. , FIFE DENNIS J. , GRABNER MARY JO , WHYTE GRACE I. 
Published: January 2008

Abstract—The anaerobic photoreduction of riboflavin, flavin mononucleotide, N(3)‐carboxymethylriboflavin, N(3)‐methyl‐lumiflavin, and lumiflavin by EDTA was studied in aqueous solution over the pH range 2.5–10. The electrostatic effects of the electron donor‐acceptor pair produce a secondary effect on the reactivity, and this effect can be predicted from the product of the charges (ZD x ZA). The trianonic and tetraanonic species of EDTA have nitrogens which are free from intramolecular hydrogen bonding, and these species are potentially the most reactive. However, in some pH regions the electrostatic effect can become the dominant factor when both the electron donor and acceptor become negatively charged. The excited states of flavins are susceptible to charge effects whether the charge is localized on the side chain or involves the isoalloxazine ring system.
SPECIES DIFFERENCES IN RESPONSE TO PHOTOHEMOLYTIC AGENTS
Authors: ROBERTSON DONALD G. , BAILEY DEBRA L. , MARTIN RONALD A. 
Published: January 2008

Abstract—Species differences in red blood cell susceptibility to the photohemolytic agents chlorpromazine, menadione and tetracycline were examined in mouse, rat, dog, and human blood. Menadione and tetracycline (25 μM) hemolyzed mouse but not dog, rat, or human red blood cells (RBC) when irradiated with UV light but not in the dark. Chlorpromazine (25 μM) produced a photohemolytic response in all four species with mouse and rat RBC lysing fastest followed by human then dog cells. Investigations into the nature of these species differences suggested that the size of mouse RBC may contribute to its high sensitivity to photohemolytic agents. An investigation of the effect of UV light on key antioxidant enzymes revealed species differences in enzyme inactivation. These data suggest that mouse RBC may be particularly vulnerable to phototoxic agents, especially those compounds which produce active oxygen species and, therefore, may prove more useful than human RBC as a model for predicting phototoxic potential of some chemical entities.
INTER AND INTRAMOLECULAR INTERACTIONS OF PORPHYRINS WITH 5,5′‐DITHIOBIS(2‐NITROBENZOIC ACID)
Authors: D'Souza Francis , Krishnan V. 
Published: January 2008

Abstract—meso‐Tetraphenylporphyrin and its metal [zinc(II) and copper(II)] derivatives form both inter and intramolecular complexes with 5,5′‐dithiobis(2‐nitrobenzoic acid) (DTNB). The nature of interaction is predominantly charge transfer (CT) in origin, with the porphyrin functioning as a II‐donor and DTNB as an acceptor. Among the covalently linked intramolecular systems, the magnitude of CT interaction varies with the position (of one of the aryl groups of the porphyrin) to which DTNB is attached as ortho meta > para. Steady‐state and time‐resolved fluorescence studies revealed electron transfer to be the dominant pathway for the fluorescence quenching in these systems. Steady‐state photolysis experiments probed using EPR and optical absorption studies have shown that electron transfer (from the excited singlet state of the porphyrin) to DTNB results in the formation of thiyl radical and production of free thiolate anion. It is found that the products of electrochemical reduction of covalently linked porphyrin‐DTNB systems are different from those observed for the photochemical studies.
ACTION SPECTRA OF PHTHALOCYANINES WITH RESPECT TO PHOTOSENSITIZATION OF CELLS
Authors: Moan Johan , Berg Kristian , Bommer Jerry C. , Western Andre 
Published: January 2008

Abstract—Human carcinoma cells (NHIK 3025 cells) and Chinese hamster cells (V79 cells) were incubated with AIPcS1, AIPcS2and AIPcS4, phthalocyanines with different lipophilicity but with similar photochemical properties when in monomeric solutions. The absorption‐ and fluorescence spectra of the dyes in the cells were recorded as well as their action spectra with respect to sensitizing cells to photoinactivation. These spectra show that under the present conditions AIPcS1is strongly aggregated in both cell lines; AIPcS2is aggregated in V79 cells but much less so in NHIK 3025 cells. A main finding is that the shapes of the action spectra are similar to that of the fluorescence excitation spectra, but not to the absorption spectra, indicating that the photosensitizing effects of the dyes are mainly due to their monomeric fraction in the cells. AIPcS2and AIPcS4localize intracellularly mainly in lysosomes while AIPcS1was found to be more diffusely distributed in cells. As measured per quantum of fluorescence emitted, AIPcS2and AIPcS2are more efficient sensitizers than AIPcS4. The difference in efficiency between AIPcS2and AIPcS4is supposedly due to a different localization pattern on the suborganelle level.
INFLUENCE OF DIETARY OMEGA‐6, ‐3 FATTY ACID SOURCES ON THE INITIATION AND PROMOTION STAGES OF PHOTOCARCINOGENESIS
Authors: Black Homer S. , Thornby John I. , Gerguis Janette , Lenger Wanda 
Published: January 2008

Abstract—To determine the segment along the carcinogenic continuum at which dietary lipid exerts its principal effect, six groups of 35 Skh‐HR‐1 hairless mice were placed on defined isocaloric diets containing either 0.75%, 12% corn oil or 12% menhaden oil as sources of omega‐6 or omega‐3 fatty acids, respectively. All animals received an 11 week course of UV‐radiation from fluorescent sunlamps. Upon termination of UV, diets of some groups were crossed‐over to either low fat, high fat, omega‐6 or omega‐3 fatty acid sources. The first tumor appeared at week 14. Life‐table analysis of the tumor incidence curves and Wilcoxon tests of tumor multiplicity provided evidence that high corn oil diets significantly (P < 0.01) enhance carcinogenic expression; that tumor enhancement by the omega‐6 fatty acid source occurs during the post‐initiation, or promotion, stage; that replacement with a low corn oil diet after UV‐initiation will negate the exacerbating effect of high corn oil; and that an omega‐3 fatty acid source inhibits UV‐carcinogenesis even at high dietary levels, although not during the post‐initiation stage.
THE PHOTOTOXICITY OF 8‐M‐ETHOXYTHIONEPSORALEN AND 6‐M‐ETHYLTHIONECOUMARIN
Authors: Tuveson R. W. , Wang Gui‐Rong , Becker Ralph S. 
Published: January 2008

Abstract—The phototoxicity of 8‐m‐ethoxythionepsoralen (8‐M‐OTP) and 6‐m‐ethylthione coumarin (6‐M‐TC) when activated by UV‐A has been investigated using a variety of Escherichia coli strains, Haemophilus influenme transforming DNA and Escherichia coli pBR322 plasmid DNA. The results demonstrate that 8‐M‐OTP is a strictly oxygen independent photosensitizer that is about 500‐f‐old less efficient in forming lesions leading to equivalent lethality than is the parent compound from which it is derived (8‐M‐OP). As is true for 8MOP, 8‐M‐OTP is capable of inducing histidine independent mutations in E. coli and inactivating transforming DNA consistent with DNA being a target for lesions induced by this molecule in the presence of UV‐A. 6‐M‐TC is a strongly oxygen dependent photosensitizer activated by UV‐A when tested with either E. coli cells or transforming DNA in contrast to the parent compound (6‐m‐ethylcoumarin; 6‐M‐C) which is not phototoxic when treated with UV‐A. These results imply that the membrane may be an important target leading to lethality. 6‐M‐TC in the presence of UV‐A can inactivate pBR322 plasmid and Haemophilus influenme transforming DNA activity in virro suggesting that DNA is a potential target for this molecule when activated by UV‐A.
POTENTIATION OF OXIDATIVE DAMAGE TO PROTEINS BY ULTRAVIOLET‐A AND PROTECTION BY ANTIOXIDANTS
Authors: Hu Miao‐Lin , Tappel Al L. 
Published: January 2008

Abstract—We have studied the damage of alcohol dehydrogenase (ADH) and glyceraldehyde 3‐p‐hosphate dehydrogenase (GAPD) induced by Fe++/EDTA + H2O2 in combination with UV‐A (main output at 365 nm). Enzyme inactivation, formation of hydroxyl radicals (measured in the absence of enzymes), increase in protein carbonyls, oxidation of sulfhydryl (SH) groups, loss of native protein fluorescence, and enhanced protease degradation were used to determine protein damage. Hydroxyl radical production was greatly enhanced by the combination of UV‐A with Fe++/EDTA + H2O2. The combined treatment increased protein carbonyls but decreased native protein fluorescence and SH groups. The combined treatment caused turbidity in GAPD but not in ADH, whereas trypsin susceptibility was increased more in ADH than in GAPD. These measurements of protein oxidation correlated well with enzyme activities. Glyceraldehyde 3‐p‐hosphate dehydrogenase and dithiothreitol were most protective against such damage, while hydroxyl radical and singlet oxygen scavengers were partially effective. Superoxide dismutase had no effect. Thus, UV‐A potentiation of protein damage induced by FE++/EDTA + H2O2 appeared to involve hydroxyl radicals and perhaps singlet oxygen but not superoxide radicals. The damage to proteins induced by combination of UV‐A with physiological oxidants, iron ions and HzO2 may be relevant to UV‐A‐induced skin and tissue damage.
INACTIVATION OF LAMBDA PHAGE WITH 658 nm LIGHT USING A DNA BINDING PORPHYRIN SENSITIZER
Authors: Kasturi Chandrika , Platz Matthew S. 
Published: January 2008

Abstract—Exposure of lambda phage to 658 nm light in the presence of 5,10,15,20‐tetrakis‐(1‐methyl‐4‐pyridyl)‐21H,23H‐prphine, tetra‐p‐tosylate leads to complete (< 7 logs) inactivation as measured by the plaque assay. The sensitizer without light and 658 nm photolysis of lambda phage in the absence of sensitizer do not lead to a measurable decrease in viral inactivity. Viral inactivation is not dependent upon the presence of oxygen.