bluuebunny/crossref_metadata_2025 huggingface dataset:
SENSITIVITIES TO MONOCHROMATIC 254‐nm AND 365‐nm RADIATION OF CLOSELY RELATED STRAINS OF Saccharomyces cerevisiae WITH DIFFERING REPAIR CAPABILITIES
Authors: Roth R. M. , Game J. C. , PEAK M. J.
Published: January 2008

Abstract— Sensitivity to monochromatic 254‐ and 365‐nm radiation was compared in closely related yeast strains with defects in one or more of the excision‐repair (rad1), error‐prone repair (rad18), or recombinational‐repair (rad51) pathways. At 254 nm, mutants defective in a single repair pathway exhibited slight to moderate UV sensitivity; those defective in two separate pathways were somewhat more UV sensitive, while triple mutants defective in all three pathways exhibited extreme UV sensitivity with a lethal event corresponding to 0.05 J m−2. Repair defects also rendered mutants sensitive to 365‐nm radiation; strains with single defects exhibited slight sensitivity, mutants with two defective pathways were more sensitive, and triple mutants exhibited maximal sensitivity with a lethal event corresponding to 2.4 times 104 J m−2. In the triple mutant (rad1, rad18, rad51) at both 254 and 365 nm, the dose per lethal event was almost identical with comparable values in a repair‐deficient double mutant (uvrA, recA) of Escherichia coli. In the E. coli mutant pyrimidine dimers are believed to be the primary cause of lethality at both wavelengths. Evidence for dimer involvement in the yeast mutant was obtained by demonstrating that lethality at both 254 and 365 nm was photoreactivated by light at 405 nm.
CAROTENE AND CYTOCHROME c DEPENDENT MITOTIC RECOMBINATION AND KILLING IN RESPONSE TO VISIBLE LIGHT AND UV‐C IN THE SMUT FUNGUS Ustilago Violacea
Authors: Kovacs Adrienne M. , Rossing William , III Oscar H. Will , Ruddat Manfred
Published: January 2008

Abstract— The carotene (carotenoid hydrocarbons) and cytochrome c compositions for the phlph+ pink diploid strain of Ustilago violacea and three newly developed color variants, white (w), orange (o), and yellow (y) were quantitatively determined using high‐performance liquid chromatography of lipid extracts and difference spectroscopy of alkali extracts. In addition, the effect of high‐intensity incandescent and far UV (UV‐C) radiation on survival and mitotic recombination in all four phlph+ strains were studied. The phlph+w and phlph+y strains contained relatively small amounts of cytochrome c; however, the phlph+y strain accumulated β‐carotene while in the phlph+w strain only the colorless carotene phytoene was found. The phlph+w was very sensitive to incandescent radiation, with complete killing by 90 min of exposure. The induction of mitotic recombination in the phlph+w strain was inversely proportional to the level of survival, with 96% induction by 90 min of exposure. The β‐carotene‐accumulating phlph+y strain was considerably more resistant to photokilling, and exhibited induction of mitotic recombination at a lower level. Similar results were observed with these strains in response to UV‐C. The phlph+y strain was significantly more resistant to UV‐C killing than the phlph+w strain and it also exhibited lower induced levels of mitotic recombination.

The phlph+o and phlph+ pink strains accumulated over 10 times the cytochrome c as the phlph+w or phlph+y strains. The phlph+o strain accumulated β‐carotene at the level of the phlph* y strain, but the phlph+ pink strain contained only about one‐tenth as much β‐carotene. The phlph+ o and phi ph+ pink strains exhibited sensitivity to visible radiation that was intermediate to the phlph+y and phlph+w strains. Mitotic recombination induction by visible radiation in the orange and pink strains was slightly less than that in the phlph+w strain. In response to UV‐C, the phlph+o and phlph+ pink strains had survival and mitotic recombination induction characteristics that were similar to the phlph+w strain.
PHOTOBLEACHING OF PORPHYRINS USED IN PHOTODYNAMIC THERAPY AND IMPLICATIONS FOR THERAPY
Authors: Mang Thomas S. , Dougherty Thomas J. , Potter William R. , Boyle Donn G. , Somer Stein , Moan Johan
Published: January 2008

Abstract— The development of an extraction procedure to quantitate dihematoporphyrin ether (DHE) concentration in tissues correlated to fluorescence measurements from instrumentation developed for in vivo fluorimetry was examined. In vivo fluorometric results from mouse mammary carcinoma (SMT‐F) were calibrated against results of the chemical extraction assay quantitated spectrophotometrically. Fluorescence and drug extractable levels increase in a linear fashion with injected dose. Loss of porphyrin fluorescence (photobleaching) and intra‐tumoral porphyrin level has been demonstrated both in vitro (NHIK cells) and in vivo (SMT‐F tumor) during illumination with light following exposure to Hpd or DHE. This process is essentially independent of porphyrin tumor level in vivo and could lead to tumor protection at very low porphyrin levels. On the other hand, this photobleaching process which occurs concurrent with cellular inactivation and tissue damage due to the photodynamic process can be exploited to protect normal tissue during photodynamic therapy (PDT) and thus greatly enhance the therapeutic ratio. This has been demonstrated in patients undergoing PDT.
SPECTROSCOPY AND PHOTOCHEMISTRY OF 8‐SUBSTITUTED 5‐DEAZAFLAVINS
Authors: Link Paul A. J. , Plas Henk C. VAN DER , Müller Franz
Published: January 2008

Abstract— Absorption, fluorescence and phosphorescence spectra as well as fluorescence and phosphorescence quantum yields of 8‐X‐5‐deazaflavins (X = C1, NO2, p‐NO2‐C6H4, N(CH3)2, NH2, p‐NH2‐C6H4, p‐N(CH3)2‐C6H4‐N=N) were determined. It was found that all these data are highly influenced by the substituent at position 8 of the 5‐deazaisoalloxazine skeleton. Also the photoreduction of 8‐X‐5‐deazaflavins in the presence of electron donors was studied. It was established that the photoreduction leads to the formation of a 5,5‘‐dimer and/or a 6,7‐dihydro compound. Reduction of the C(6)‐C(7) bond is promoted by strong electron‐donating substituents and bulky electron donors. 5‐Deazaftavins with a reducible substituent at position 8 exhibit reduction of the substituent prior to the reduction of the 5‐deazaisoalloxazine skeleton.
SPECTROSCOPIC STUDIES OF CUTANEOUS PHOTOSENSITIZING AGENTS—X. A SPIN‐TRAPPING AND DIRECT ELECTRON SPIN RESONANCE STUDY OF THE PHOTOCHEMICAL PATHWAYS OF DAUNOMYCIN AND ADRIAMYCIN
Authors: Li Anson S. W. , Chignell Colin F.
Published: January 2008

Abstract— Irradiation of daunomycin (or adriamycin) and the spin trap 5,5‐dimethyl‐l‐pyrroline‐1‐oxide (DMPO) at 490 nm in the presence or in the absence of air generated the hydroxyl radical adduct (DMPO‐OH). The observed DMPO‐OH signal was not affected by the addition of hydroxyl radical scavengers (ethanol, formate), suggesting that direct trapping of the hydroxyl radical was not involved. The DMPO‐OH signal was insensitive to superoxide dismutase and catalase, which ruled out the possibility of superoxide or H2O2 involvement. These findings demonstrate that daunomycin (or adriamycin) does not generate hydroxyl radicals or superoxide radical anions when subjected to 490‐nm excitation. However, when daunomycin (or adriamycin) was irradiated at 310 nm DMPO adducts derived from two carbon‐centered radicals, superoxide and the hydroxyl radical were detected. The superoxide adduct of DMPO was abolished by the addition of SOD, providing unequivocal evidence for the generation of the superoxide anion radical. The daunomycin semiquinone radical, observed upon 310‐nm irradiation of daunomycin in the absence of DMPO, appears to be the precursor of the superoxide radical anion. One of the carbon‐centered radicals trapped by DMPO exhibited a unique set of hyperfine parameters and was identified as an acyl radical. This suggests that the known photochemical deacylation of daunomycin occurs via a homolytic cleavage mechanism. The free radicals generated photolytically from adriamycin and daunomycin may be involved in the etiology of the skin ulceration and inflammation caused by these drugs. A knowledge of the dependence of these photogenerated radicals on the wavelength of excitation may be important in the development of adriamycin and daunomycin for photodynamic therapy.
BIOLOGICAL ACTIVITIES OF PHTHALOCYANINES—VI. PHOTOOXIDATION OF L‐TRYPTOPHAN BY SELECTIVELY SULFONATED GALLIUM PHTHALOCYANINES: SINGLET OXYGEN YIELDS AND EFFECT OF AGGREGATION
Authors: Wagner J. Richard , Ali Hasrat , Langlois RÉjean , Brasseur Nicole , VAN Ller Johan E.
Published: January 2008

Abstract— The photosensitized oxidation of L‐tryptophan by gallium phthalocyanines sulfonated to different degrees is studied as a function of both substrate and sensitizer concentrations in water and 50% MeOH‐H2O solutions. The maximum quantum yield of singlet oxygen was found to be nearly 0.5 for all sulfonated gallium complexes. The effect of adding sulfonate groups in the phthalocyanine backbone is to change the tendency of dye molecules to dimerize or aggregate in a particular solvent. A shift in the chemical equilibrium away from the monomeric state, which occurs at high dye concentrations and at lower degrees of dye sulfonation, results in a reduced photochemical yield. The variation of quantum yields in different solvent systems and at several wavelengths is similarly accounted for by the fraction of light absorbed by the productive monomer state.
LIPID PEROXIDATION AND OTHER MEMBRANE DAMAGE PRODUCED IN Escherichia coli K1060 BY NEAR‐UV RADIATION AND DEUTERIUM OXIDE
Authors: Chamberlain J. , Moss S. H.
Published: January 2008

Abstract— With accumulating evidence that the membrane is an important site for near‐UV inactivating events, we have investigated the effects of near‐UV radiation on the unsaturated fatty acid auxotroph E. coli K1060 following incorporation into the membrane phospholipids of fatty acids with varying degrees of unsaturation. Sensitivity, lipid peroxidation and membrane damage, as determined by 86Rb+ leakage, have been found to increase with increasing unsaturation in log‐phase cells. Similar experiments carried out in D2O also show an increase in sensitivity, lipid peroxidation and membrane damage, indicating that singlet oxygen may be responsible for such near‐UV‐radiation‐induced damage
PHOTOPEROXIDATION OF LENS LIPIDS: INHIBITION BY ASPIRIN
Authors: Beachy N. A. , Morris S. M. , Richards R. D. , Varma S. D.
Published: January 2008

Abstract— Rat lenses have been organ cultured in light and dark, and peroxidative degradation of lipids studied in the presence and absence of aspirin. The extent of peroxidative degradation has been assessed by measurement of malonaldehyde. The light‐stimulated peroxidative degradation of the tissue lipids has been found to be preventable by aspirin. Aspirin thus appears to be a potential agent against light damage to the tissue.
TEMPERATURE DEPENDENCE OF PHOSPHORESCENCE PARAMETERS OF PHYLOGENETICALLY DISTANT APOMYOGLOBINS
Authors: Bismuto Ettore , Strambini Giovanni B. , IRACE GAETANO
Published: January 2008

Abstract. The triplet state lifetime and the position of the O—O vibrational band of the tryptophanyl phosphorescence spectrum of two philogenetically distant apomyoglobins, i.e. tuna and sperm whale apomyoglobin, have been studied at different temperatures. The temperature dependence of the two phosphorescence parameters revealed that the tryptophanyl microenvironment possesses different dynamic characteristics in the two examined proteins. In particular, the tryptophanyl side chain of tuna apomyoglobin was found embedded into a less rigid microenvironmental cluster which possesses a higher degree of internal flexibility than that of sperm whale apomyoglobin.
TEMPERATURE AND VISCOSITY DEPENDENCE OF FLUORESCENCE QUENCHING BY OXYGEN IN MODEL SYSTEMS
Authors: Eftink M. R. , Ghiron C. A.
Published: January 2008

Abstract— The bimolecular rate constant, kq, for the quenching of the fluorescence of pyrenebutyric acid and naphthaleneacetic acid by molecular oxygen has been studied as a function of temperature and viscosity, η. Fluorescence lifetime measurements were used to monitor the degree of quenching. Glycerol‐water and sucrose‐water mixtures were used to increase the bulk viscosity. Plots of log kqvs log η show deviations from Stokes‐Einstein behavior, but the data are consistent with the patterns that have been observed for other diffusion limited reactions. This work provides background information, regarding the viscosity dependence of oxygen quenching reactions, which is essential for the correct interpretation of oxygen quenching/viscosity dependence studies with more complex systems (i.e. quenching of tryptophan residues in proteins).
THE USE OF SPECIFIC RADIOIMMUNOASSAYS TO DETERMINE ACTION SPECTRA FOR THE PHOTOLYSIS OF (6‐4) PHOTOPRODUCTS
Authors: Mitchell David L. , Rosenstein Barry S.
Published: January 2008

Abstract. A radioimmunoassay (RIA) was developed which specifically detects a photoproduct produced by the near‐UV photolysis of pyrimidine(6‐4)pyrimidone photoproducts. This assay was used in conjunction with a previously characterized RIA which specifically detects (6‐4) photoproducts to determine the relative efficiency of wavelengths between 265 and 435 nm for photolysing these lesions. The rate of loss of antibody‐binding sites associated with (6‐4) photoproducts correlates with the production of those associated with its photolysis product. Action spectra for both the loss of (6‐4) photoproducts and the induction of the photolysis product parallel the absorption spectrum of the (6‐4) photoproduct.
THE EFFECT OF ACIDS ON THE INFRARED SPECTRA OF SCHIFF BASES—II. IMINES CONTAINING THE C=C‐C=N AND C=C‐C=C‐C=N UNITS
Authors: Lussier L. S. , Sandorfy C. , L E‐Thanh H. OA , Vocelle D.
Published: January 2008

Abstract— The Fourier‐transform infrared spectra of chloroform‐d solutions of conjugated imines CH3CH=CHCH=NCH(CH3)2 and CH3CH2CH=CHCH=CHCH=NCH(CH3)2 and the related protonated species with HCl, HBr, HI, trichloro, dichloro, monobromo and monochloroacetic acids or propionic acid are presented. The effects of conjugation and protonation are examined. The results show that conjugation slightly increases the basicity of the Schiff bases. HCl, HBr and HI protonate the Schiff bases completely. The carboxylic acids protonate partially depending on their pKa, values. When the Schiff base contains two (or more) C=C bonds conjugated with C=N, the main C=C stretching band undergoes a strong intensification showing that sizeable dipole moment variations occur along the conjugated chain.
EVIDENCE FOR A SEQUENTIAL PATHWAY FROM Pr TO Pfr OF THE PHOTOTRANSFORMATION OF 124‐kDa OAT PHYTOCHROME
Authors: Eilfeld Peter , Eilfeld Petra , Vogel Jürgen , Maurer Robert
Published: January 2008

Abstract. Phototransformation kinetics of 124‐kDa oat phytochrome at 298 K after a red (660‐nm) laser flash excitation were recorded at different wavelengths. The kinetics of the dark relaxation processes for lumi‐R to Pfr can be satisfactorily described by only 3 rate constants: k= 28000 s‐1 370 s‐1 and 20 s‐1. The first rate constant is due to the decay of lumi‐R to meta‐Ra. The latter two rate constants correspond to processes establishing the far‐red (>700 nm) absorption band. No meta ‐Rb could be detected. From the wavelength dependency of the amplitudes of these two rates, parallel pathways in the formation of Pfr could be excluded. A unique sequential pathway for the dark relaxation leading to Pfr seems to be an intrinsic property of 124‐kDa phytochrome, however. Assuming a sequential pathway, molar extinction coefficients for intermediates have been calculated. These values agree with molar extinction coefficients obtained from low‐temperature spectra. The process with a rate constant of 370 s‐1 corresponds to absorbance changes for the formation of meta‐Rc from meta‐Ra and the rate constant of 20 s‐1 describes the absorbance changes due to the transformation of meta‐Rc to Pfr.
TAUTOMERISM AND FLUORESCENCE OF LUMAZINE
Authors: Klein R. , Tatischeff I.
Published: January 2008

Abstract— The fluorescence properties of lumazine, 1‐methyl‐lumazine (1‐ML) and 3‐methyl‐lumazine (3‐ML) in aqueous solution are pH dependent. Emissions with the following maxima were attributed to the four ionic species of lumazine: dianion (483 nm), monoanion (467 nm), neutral (380 nm) and monocation (505 nm). Neutral lumazine emitted, besides, a fluorescence at 481 nm with a large Stokes shift (10 000 cm‐1). As a similar emission is observed with 3‐ML but not with 1‐ML, we suggest as emitting species the N(8)‐H‐phototautomer resulting from the N(l) to N(8) proton transfer in the excited state. At pH 10, the fluorescence quantum yield of 3‐ML, Qf= 0.24 ± 0.02 was higher than that of 1‐ML, Qf= 0.015 ± 0.002. At this pH, lumazine is a mixture of N(l)‐deprotonated and N(3)‐deprotonated monoanions, the emitting properties being principally due to the N(l)‐deprotonated species, Qf= 0.24 ± 0.02. The evaluation of the ionization constants in the excited state are discussed in relation to the tautomeric nature of the emitting species.
3‐CARBETHOXYPSORALEN‐DNA PHOTOLESIONS: IDENTIFICATION AND QUANTITATIVE DETECTION IN YEAST AND MAMMALIAN CELLS OF THE TWO cis‐syn DIASTEREOISOMERS FORMED WITH THYMIDINE
Authors: Moysan A. , Vigny P. , Dardalhon M. , Averbeck D. , Voituriez L. , Cadet J.
Published: January 2008

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 two cis‐syn dThd(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 10 000 base pairs.
PROTECTION AGAINST DIHEMATOPORPHYRIN ETHER PHOTOSENSITIVITY
Authors: Manyak Michael J. , Smith Paul D. , Harrington Frank S. , Steinberg Seth M. , Glatstein Eli , Russo Angelo
Published: January 2008

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/cm2 of 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 administration.
THE ACTION SPECTRUM IN DRUG INDUCED PHOTOSENSITIVITY
Authors: Diffey B. L. , Farr P. M.
Published: January 2008

Abstract— A new method is proposed for expressing the data obtained from in vivo studies of drug‐induced photosensitivity. It is shown that consideration of the underlying normal photobiological responses that occur in the absence of the photosensitising drug can yield much closer agreement between the in vitro absorption spectrum of the drug and the action spectrum obtained in photosensitised skin than is apparent from many published reports.
SPECTRAL AND TIME DEPENDENCE STUDIES OF THE ULTRA WEAK BIOLUMINESCENCE EMITTED BY THE BACTERIUM Escherichia coli
Authors: Tilbury R. N. , Quickenden T. I.
Published: January 2008

Abstract— Weak luminescence was detected using photon counting equipment, from oxygenated, liquid cultures of Escherichia coli during two stages of its growth cycle. The first period of emission occurred during the exponential phase of growth and comprised a UV(210–330 nm) band and a visible region(450–620 nm) band, the total intensity being (1.65 ± 0.12) x 103 counts s‐1. The second period of emission occurred during the stationary phase of growth and comprised only a visible region(450–620 nm) band of intensity (8.72 ± 0.15) x 103 counts s‐1. When the growth temperature was raised from 306.15 to 310.15 K, the above emission intensities were approximately halved, but the spectra were not changed significantly. No luminescence was observed at either temperature when the E. coli was grown anaerobically. The visible region luminescence was attributed to excited carbonyl groups and excited singlet O2 dimers formed during the decomposition of lipid peroxides. The UV component was tentatively assigned to oxidative side reactions accompanying the synthesis of proteins.
EFFECT OF CHRONIC UV EXPOSURE ON EPIDERMAL FORWARD SCATTERING‐ABSORPTION INSK–1 HAIRLESS MOUSE SKIN
Authors: Menter Julian M. , Agin Patricia P. , Sayre Robert M. , Willis Isaac
Published: January 2008

Abstract— Clinical and histological precancerous responses to UV irradiation are complicated dynamic functions of total dose, dose fractionation, fluence rate, and spectral distribution. This may be due, in large part, to the ability of UV to decrease epidermal‐stratum corneum transmission by stimulation of hyperplasia. This work provides quantitative measurement of dose‐ and wavelength‐dependent optical changes inSK–1 hairless mouse epidermis‐stratum corneum occurring under irradiation with “monochromatic” UV wavebands, at 280, 290, 300, 307, and 313 nm. Mice were irradiated 5 days per week with a filtered Xenon‐Hg high‐intensity grating monochromator, starting with 0.9 minimal erythemal dose (MED), followed by incremental increases in the radiation dose by 20% of the original dose every tenth irradiation day, for2–8 consecutive weeks. Subsequent irradiations (for longer experiments) were followed by 30% incremental increases after the 8th week every 10th irradiation day until cessation of radiation at the end of 14 weeks. Irradiated and control full‐thickness epidermis/ stratum corneum were examined histologically and by forward‐scattering absorption spectroscopy. Chronic irradiation of hairless mice resulted in significant hyperplasia which was optically manifested by a general increase in forward‐scattering absorbance. At moderate local doses (7.2 MED), the absorbance increase per MED was approximately the same for all excitation wavelengths, whereas at large total doses (≅ 100 MED) the optical increase per delivered MED progressively decreased in the order 313> 307> 300≅ 290> 280 nm. The increase in skin thickening, expressed as observed increase in absorption at 320 nm, correlated well with histological and clinical data. We propose that optical changes induced by UV‐induced thickening can account in large part, if not entirely, for dynamic changes in action spectra for (pre) cancerous processes under chronic irradiation conditions.
124‐kDa PHYTOCHROME IN MODEL MEMBRANE SYSTEMS: STUDIES OF THE Ii700 INTERMEDIATES WITH THE PROTEIN COVALENTLY BOUND TO PREFORMED LIPOSOMES
Authors: Krieg Marianne , Aramendia Pedro F. , Braslavsky Silvia E. , Schaffner Kurt
Published: January 2008

Abstract— We have described the covalent binding of 124‐kDa oat phytochrome to large unilamellar liposomes composed of either dioleoyl phosphatidylcholine or dipalmkoyl phosphatidylcholine or soybean lecithin, without affecting the photochromic properties of the protein. These phytochrome‐liposome systems have now been studied by laser flash photolysis. The liposomes, independent of their membrane rigidity (liquid‐crystal vs gel‐like phase), do not influence the ratio and reactivity of the two primary photoproducts, Ii700‐ of the red absorbing form of phytochrome, Pl Thus, the lifetimes of the Ii700 intermediates and the activation parameters associated with Ii700Iibl are the same as those measured for nonbound phytochrome in buffer solution. The temperature increase from about 273 K. to 297 K lowers the population of the shorter‐lived Ii700 intermediate to the same extent both in the liposome‐Pl and in nonbound Pl, whereas it does not affect the relative population of the Ii700 intermediates from non‐bound Pl in the presence of 25% ethylene glycol added to the buffer solution (ionic strength 0.17).
PHOTOLYSIS OF AMIODARONE, AN ANTIARRHYTHMIC DRUG
Authors: Paillous Nicole , Verrier Martine
Published: January 2008

Abstract— The photochemical behaviour of amiodarone was examined in vitro in order to get more insight on the chemical reactions involved in the cutaneous phototoxicity processes. Irradiation at 300 nm of amiodarone degassed in ethanol solution leads to a photodehalogenation followed by a much slower α‐cleavage reaction. Desethylamiodarone, the main metabolite of AD was found to undergo the same reaction as AD. Results of photosensitization and quenching experiments together with phosphorescence spectra indicated that the reaction proceeds via the triplet excited stateof amiodarone. Radical species formed during photolysis were identified by ESR spectroscopy. CH3CHOH, HO2 and an unidentified radical were detected using 5,5‐dimethyl‐1‐pyrroline‐1‐oxide as spin trap. In aerated solutions, photosensitization of oxygen by amiodarone was demonstrated by adding singlet oxygen scavengers such as dimethylfuran and cholesterol. Overall, these results suggest that Type I and Type II mechanisms may take place in the phototoxicity of amiodarone and its metabolite.
A HIGH RESOLUTION FLUORESCENCE DECAY AND DEPOLARIZATION STUDY OF HUMAN PLASMA APOLIPOPROTEINS
Authors: Chang Mary C. , Fleming Graham R. , Scanu Angelo M. , Yang Nien‐chuC
Published: January 2008

Abstract— Human plasma apolipoprotein A‐I (apoA‐I) and apolipoprotein C‐I (apoC‐I) were investigated by time‐resolved fluorescence decay and depolarization. The tryptophyl fluorescence of apoA‐I undergoes a double‐exponential decay with lifetimes of 1.07 and 3.43 ns which remain unchanged over the range of apoA‐I concentration studied.

The time‐resolved fluorescence of both native and denatured forms of apoC‐I exhibits an unusual tryptophyl fluorescence decay that was best fit to a triexponential function with lifetimes at 3.7 ± 0.2, 1.1 ± 0.1 and 0.1 ns at 2°C. The native and denatured forms of apoC‐I had rotational correlation times of 1.42 and 1.19 ns at 20°C respectively. A shorter rotational correlation time associated with the internal tryptophan motions was not observed or resolved.

The decay of tryptophyl fluorescence in apoC‐I/DPPC/cholesterol complex at 20°C is also triexponential with lifetimes at 4.94, 1.28 and 0.21 ns, which are longer than those of the uncomplexed forms. Two rotational correlation times of 28.32 and 0.59 ns at 20°C were resolved by fluorescence depolarization measurements. The long rotational time remained constant with temperatures above 30°C. Also, the temperature dependence of the order parameter, S2, resembled a lipid phase transition curve with a transition midpoint at 38°C. The tryptophan and thus apoC‐I are found to be affected by the bulk changes in the lipid.
CORRELATION BETWEEN ENDOGENOUS GLUTATHIONE CONTENT AND SENSITIVITY OF CULTURED HUMAN SKIN CELLS TO RADIATION AT DEFINED WAVELENGTHS IN THE SOLAR ULTRAVIOLET RANGE
Authors: Tyrrell R. M. , Pidoux M.
Published: January 2008

Abstract— Glutathione depletion of cultured human skin fibroblasts by treatment with buthionine‐S,R‐sulfoximine (BSO) sensitises them to radiation at a series of defined wavelengths throughout the solar UV range. We now show that there is a close quantitative correlation between cellular glutathione content (as depleted by BSO) and sensitivity to radiation at 365 nm. A weaker correlation is observed when cells are depleted of glutathione using diethylmaleimide. Both fibroblasts and epidermal keratinocytes derived from the same foreskin biopsy are sensitised to radiation at 313 nm by glutathione depletion. However, the keratinocytes are sensitised to a much lesser extent, an observation which agrees quantitatively with the higher residual levels of cellular glutathione remaining after maximum depletion by BSO (approximately 25% for the keratinocytes vs less than 5% for the fibroblasts). At low to intermediate fluence levels, 10 mM cysteamine present during irradiation at 302 nm is able to almost completely reverse the sensitising effects of glutathione depletion suggesting that the endogenous thiol protects against radiation at this wavelength by a free radical scavenging mechanism. At 313 nm, the sensitisation is not reversed by cysteamine suggesting that glutathione plays a more specific role in protection against radiation at longer wavelengths. Xeroderma pigmentosum group A fibroblasts (excision deficient) are also sensitised to radiation at 313 and 365 nm by depletion of glutathione but since the sensitization is less than that observed for the normal strain, we cannot conclude that glutathione protects against a sector of DNA damage susceptible to excision repair. The results provide further evidence that endogenous glutathione is involved in protecting human skin cells against a wide range of solar radiation damage and suggest that while free radical scavenging is involved at the shortest wavelength (302 nm) tested, a more specific role of glutathione is involved in protection against radiation at longer wavelengths.
PHOTOSENSITIZATION BY ANTITUMORAGENTS–6. PRODUCTION OF SUPEROXIDE RADICAL AND HYDROGEN PEROXIDE DURING ILLUMINATION OF DIAMINOANTHRACENEDIONES IN THE PRESENCE OF NADH IN AQUEOUS SOLUTIONS: AN EPR STUDY
Authors: RESZKA KRZYSZTOF , KOLODZIEJCZYK PAWEL , TSOUNGAS PETROS G. , LOWN J. WILLIAM
Published: January 2008

Abstract— Photosensitizing capabilities of anthracenedione anticancer agents to oxidize NADH in aqueous solutions have been studied by EPR and spin trapping techniques. It is demonstrated that 1,4‐diamino substituted anthraquinones, like mitoxantrone and ametantrone, do not photosensitize NADH oxidation while 1,5‐ and l,8‐bis[[(diethylamino)ethyl]amino]anthraquinones do, undergoing simultaneous one‐electron reduction to their semiquinone radical forms upon illumination with visible light. In aerated aqueous solutions the reaction leads to the production of superoxide ion and hydrogen peroxide.
A NEW ELECTRONIC ABSORBANCE BAND IN CONCENTRATED AQUEOUS SOLUTIONS OF HEMATOPORPHYRIN IX DETECTED BY PHOTOACOUSTIC SPECTROSCOPY
Authors: Pottier R. , Lachaine A. , Pierre M. , Kennedy J. C.
Published: January 2008

Abstract— Photoacoustic (PA) spectroscopy reveals a new electronic transition in concentrated aqueous solutions of hematoporphyrin IX (Hp). This new band has a maximum near 440 nm. Its intensity is sensitive to pH, concentration, PA chopping frequency, and the presence of sodium dodecyl sulfate (SDS). Data presented support the assignment of this new band to a dimeric form of Hp. The pH effects on this new band are discussed in terms of their implications for the selective biodistribution of certain porphyrin‐based photochemotherapeutic agents.
UROCANIC ACID PHOTOBIOLOGY. PHOTOOXIDATION AND SUPEROXIDE FORMATION*
Authors: Morrison Harry , Deibel Rose Marie
Published: January 2008

Abstract— Photolysis of urocanic acid (UA) and nitro blue tetrazolium (NBT2+), under conditions wherein the NBT2+ absorbs the light, leads to oxidation of the UA by the NBT2+ excited state. When UA is itself photolyzed in the presence of oxygen and NBT2+, NBT2+ reduction again occurs, but in this event via the intermediate formation of superoxide.
SYNTHETIC PORPHYRINS AT INTERFACES; PHOTOSENSITIZATION AND RELATED REACTIONS OF ATROPISOMERS OF o‐SUBSTITUTED TETRAPHENYLPORPHINE DERIVATIVES IN FILMS, REVERSED MICELLES AND MEMBRANES †
Authors: Collins‐Gold L. C. , Barber D. C. , Hagan W. J. , Gibson S. L. , Hilf R. , Whitten D.G.
Published: January 2008

Abstract— Previous studies from our laboratories and elsewhere have shown that amides between fatty acids and the synthetic α, α, α, α ‐tetra (o‐aminophenyl)‐porphyrins exhibit good surfactant properties which facilitate their incorporation into structured assemblies characterized by hydrophobic‐hydrophilic compartmentalization. This paper will focus on a number of aspects of our studies of these porphyrins at different interfaces.

The α, α, α, α (4,0) isomers are readily incorporated into Langmuir‐Blodgett films as either free base or metal complexes. Studies of assemblies containing free base and palladium (II) complexes have been carried out in which the porphyrin is irradiated in the presence of oxygen and nonexcited but oxidizable substrates. Much of the reactivity observed can be attributed to 1O2* generation. These studies reveal the migration range and reactivity of activated oxygen in a structure related to biomem‐branes.

Several of these synthetic porphyrins have also been examined in cell suspensions and in synthetic reversed micelle solutions. Studies in the former have shown that the porphyrins can mediate the photoinactivation of several enzymes located inside and within the mitochondrial membrane in tumor cells extracted from rats. They are found to compare favorably to hematoporphyrin derivative in effectiveness.

Studies of the same porphyrins in their reactivity towards copper ion incorporation in anionic reversed micelles indicate striking rate differences which can be interpreted in part to structural variations between the porphyrins as well as to their orientation at the hydrophobic‐hydrophilic interface.
EFFECTS OF METAL CATIONS, RETINAL, AND THE PHOTOCYCLE ON THE TRYPTOPHAN EMISSION IN BACTERIORHODOPSIN
Authors: Jang Du‐Jeon , Corcoran TimothyC. , El‐Sayed M. A.
Published: January 2008

Abstract— The picosecond fluorescence kinetics of tryptophan residues in bacteriorhodopsin and some perturbed analogs are measured to study the different tryptophan environments and their changes upon metal cation removal, retinal removal, and M412 trapping. In bacteriorhodopsin, the emission shows four decay components designated Or, C2r, C3r, and C4r in order of increasing lifetimes. The emission wavelength of C3r and C4r is near that found in aqueous solution, while that of C1r is the shortest. The removal of retinal triples the total emission intensity and reduces the number of components to two, suggesting that the observed variation of the lifetimes in bacteriorhodopsin results from the variation of the energy transfer efficiency between different tryptophans and retinal. We conclude that the Or and C2r emission is from the closest tryptophans to the retinal. The quenching of the C3r emission by all metal cations, including those that cannot act as energy acceptors, e.g. Ca2+, is attributed to protein conformation changes caused by metal cation binding which leads to a stronger energy transfer coupling between tryptophans and retinal. The additional quenching of the C2r emission in Eu3+bound bacterioopsin is proposed to result from direct energy transfer between tryptophans and Eu3+.
THE INTERPRETATION OF THE ELECTRON SPIN RESONANCE SPECTRUM OBTAINED BY ULTRAVIOLET IRRADIATION OF THE PHOTO ALLERGEN BITHIONOL
Authors: Delahanty Jonathan N. , Evans Jeffrey C. , Rowlands Christopher C. , Barratt Martin D.
Published: January 2008

Abstract— The initial radical produced on UV irradiation of the photoallergen bis(2‐hydroxy‐3,5‐dichlorophenyl) sulphide (bithionol) in aqueous solution (pH 8) has been characterised involving chlorine isotope interaction (35Cl 0.059, 37Cl 0.049 mT) in the interpretation of the ESR spectrum. This is the first time that this effect has been observed in solution in these systems.
PHOTOPHYSICAL PROPERTIES OF meso‐TETRAPHENYLPORPHYRIN and SOME meso‐TETRA(HYDROXYPHENYL)PORPHYRINS
Authors: Bonnett R. , McGarvey D. J. , Harriman A. , Land E. J. , Truscott T. G. , Winfield U‐J.
Published: January 2008

Abstract— The o‐, m‐, and p‐isomers of 5, 10, 15, 20‐ tetra(hydroxyphenyl)‐porphyrin have been of recent interest as potential second‐generation sensitisers in tumour phototherapy. Fluorescence spectroscopy, nanosecond laser flash photolysis and pulse radiolysis have been used to characterise the singlet and triplet excited states of tetraphenylporphyrin and the o, m‐, and p‐isomers of tetra(hydroxyphenyl)porphyrin. This has included evaluation of fluorescence yields and lifetimes, triplet spectra, lifetimes, oxygen quenching rate constants, extinction coefficients, and yields and singlet oxygen yields. Whilst the fluorescence quantum yields were low, the triplet yields were all 0.7 ± 10% and the singlet oxygen yields 0.6 ± 10%: all these parameters are in the ranges shown by other efficient porphyrin photosensitisers. The similar photophysical properties found for these compounds suggest that their differing tumour sensitising efficiencies are likely to be due to other factors.
MECHANISM OF PHYSICAL QUENCHING OF SINGLET MOLECULAR OXYGEN BY CHLOROPHYLLS and RELATED COMPOUNDS OF BIOLOGICAL INTEREST
Authors: Tanielian C. , Wolff C.
Published: January 2008

Abstract— The rate constant k5/ > for physical quenching of singlet oxygen O2(δ1;) by the sensitizer in dye‐sensitized photooxygenations is determined in the case of chlorophylls a and b (7.3 times 108, 4.2 times 108 M‐1 s‐1 respectively), pheophytins a and b (7.4 times 107, 3.0 times 107M‐1 s_1 respectively), tetraphenylporphyrin (4.4 times 107 M‐1 s_1), magnesium tetraphenylporphyrin (5.0 times 108M‐1 s_1), zinc tetraphenylporphyrin (1.5 times 108 M‐1 s_l) and protoporphyrin IX‐dimethylester (9.1 times 107M‐1 s_1) in benzene. These sensitizers show a linear correlation between log ksO, and their half‐wave oxidation potentials and the value of the slope is similar to that observed for various compounds such as phenols. It is concluded that (i) the interaction between chlorophylls and related compounds with singlet oxygen may involve an exciplex as for phenols, and (ii) physical quenching may be envisaged as a spin‐orbit‐induced intersystem crossing within the exciplex.
DYNAMICS OF ANTHRACYCLINES/DNA INTERACTION: A LASER TIME‐RESOLVED FLUORESCENCE STUDY*
Authors: Malatesta Vincenzo , Andreoni Alessandra
Published: January 2008

Abstract— The dynamic interaction with DNA of two representative anthracyclines, daunomycin and 5‐iminodaunomycin, differing in the redox properties, DNA affinity and cardiotoxicity, has been characterized by laser time‐resolved fluorescence decay. The free drug fluorescence decay is mono‐exponential for daunomycin in both phosphate and TRIS buffer and becomes biexponential in the case of 5‐iminodaunomycin when the phosphate buffer is used. In the presence of DNA, daunomycin excited with a mode‐locked Ar laser at 364 nm shows a three‐exponential fluorescence decay with time constants T1=2.92 ns, T2= 1.42 ns, T3=0.31 ns. The first lifetime refers to the decay of the excited state of the chromophore bound on the DNA backbone, whereas T2 and T3 are assigned to two different conformations of the intercalation complex. An estimate of the molar extinction coefficient and the relative quantum yield of the variously bound drug is made. The 5‐iminodaunomycin fluorescence decay lifetime is less sensitive to the nature of the environment probably because, being a poorer intercalator, it binds more easily on the phosphate backbone and thus the electronic perturbation resulting from the binding is not as strong as in the case of daunomycin.
INHIBITORY EFFECTS OF ETHANOL ON THE PHOTODYNAMIC CELL INACTIVATION AND PETITE INDUCTION BY EUFLAVINE IN YEAST, Saccharomyces cerevisiae
Authors: Tsuchiya M. , Iwamoto Y. , Masuzawa T. , Shimizu T. , Morita T. , Yanagihara Y.
Published: January 2008

Abstract— Effects of active oxygen scavengers on cell inactivation and petite induction of yeast by the photodynamic action of euflavine were examined. Histidine, sodium azide, 1,3‐diphenyl‐isobenzofuran and p‐carotene, which are singlet oxygen scavengers, inhibited photodynamic cell killing. Histidine and sodium azide inhibited petite induction, too. These results suggested that photobiological effects of euflavine are induced via singlet oxygen‐mediated Type II reaction process. In this work, however, we found that ethanol, which is reported to be a hydroxyl radical scavenger, notably inhibited photodynamic cell inactivation and petite induction by euflavine. Inhibition of petite induction was increased with increasing concentration of ethanol. Decrease of absorbance of euflavine by irradiation was also inhibited by the addition of ethanol.

These results suggested that ethanol possibly acts as a singlet oxygen scavenger.
LUMIFLAVIN‐SENSITIZED PHOTOOXYGENATION OF INDOLE
Authors: Yoshimura Akio , Ohno Takeshi
Published: January 2008

Abstract— The lumiflavin‐sensitized photooxygenation of indole in aqueous solutions has been investigated by means of steady light photolysis and flash photolysis. The semiquinone of lumiflavin and the half‐oxidized radical of indole were formed by the reaction between triplet lumiflavin and indole (3.7 times 109M‐1 s‐1). The semiquinone anion radical of lumiflavin reacted with oxygen to form superoxide radical. The triplet state of lumiflavin also reacted with oxygen forming singlet oxygen, 1O2. But the reaction between 1O2 and indole (7 times 107 M_l s_1; estimated from steady light photolysis using Rose Bengal as a sensitizer) was far less efficient than the reaction between indole and triplet lumiflavin. The quantum yield of the lumiflavin‐sensitized photooxygenation of dilute indole via radical processes was much higher than that via1O2 processes, though appreciable 1O2 was formed.
RESPONSE DIFFERENCES BETWEEN TWO SOYBEAN CULTIVARS WITH CONTRASTING UV‐B RADIATION SENSITIVITIES
Authors: Murali N. S. , Teramura Alan H. , Randall Stephen K.
Published: January 2008

Abstract— Soybeans (Glycine max [L.] Men. cvs. Essex and Williams) were grown in an unshaded greenhouse under two levels of biologically effective ultraviolet‐B (UV‐BBE) radiation (effective daily dose: 0 and 11.5 kJ m‐2) for 34 days. Ultraviolet‐B radiation reduced leaf area and total plant mass in Essex but these parameters were unaffected in Williams. Differences in both anatomical and biochemical characteristics were found between cultivars. Some of these differences were inherently distinct between cultivars while others were variably induced by UV treatment. Specific leaf weight. an estimate of leaf thickness, was unchanged in Essex but increased in Williams with UV‐B irradiation. The relative increase in concentration of UV‐absorbing compounds in leaf tissues after UV‐B irradiation was greater in Williams. The composition of UV‐absorbing compounds in leaf tissues differed between the two cultivars but was unaffected by UV‐B radiation. Although total soluble proteins and total peroxidase activity were similar between cultivars, several electrophoretically distinct peroxidase activities were detected. Therefore, the intraspecific variation in UV‐B sensitivity found in soybean appears to be correlated with a suite of anatomical and biochemical differences, including leaf thickness, composition and concentration of UV‐absorbing compounds in leaf tissues, and possibly differences in peroxidase activities.
PREVENTION OF UV IRRADIATION INDUCED SUPPRESSION OF MONOCYTE FUNCTIONS BY RETINOIDS AND CAROTENOIDS in vitro
Authors: Schoen David J. , Watson Ronald R.
Published: January 2008

Abstract— The effects of stimulation of human peripheral blood monocytes in vitro with retinoids and carotenoids, and subsequent exposure to ultraviolet light of the B wavelength were measured. The compounds were applied to the monocytes in culture for 24 h, and the washed cells were then exposed to UVB light up to 220 J/m2. The compounds tested protected the monocyte from UVB induced damage to phagocytic activity. This protection may be due to the antioxidant or UVB energy‐quenching properties of these compounds. Monocyte cytotoxicity against a melanoma cell line was stimulated by exposure to the retinoids or carotenoids, but a protective effect in vitro against UVB damage was not seen for this cell function.
β‐CARBOLINE ALKALOIDS: MECHANISMS OF PHOTOTOXICITY TO BACTERIA AND INSECTS
Authors: Larson Richard A. , Marley Karen A. , Tuveson Robert W. , Berenbaum May R.
Published: January 2008

Abstract— Phototoxicity of five naturally occurring (3‐carboline alkaloids was assayed against a series of Escherichia coli strains and against the insect Trichoplusia ni (Lepidoptera: Noctuidae). Rank order efficacy of the compounds was comparable in both organisms. Although the bacterial assay demonstrated oxygen dependence, the degree of phototoxicity did not correlate with the relative efficiency of in vitro singlet oxygen or hydrogen peroxide photoproduction by the alkaloids. A better correlation was observed between chromatographic migration distances (lipophilicity) and phototoxicity. Therefore, hydrophobic mechanisms in which the alkaloids diffuse with varying efficiencies into cells or into the vicinity of target molecules may be important modes of phototoxicity for these compounds.
CHLORINATION OF ISOLATED CHLOROPHYLLS in vitro
Authors: Senge Mathias , Senger Horst
Published: January 2008

Abstract— It was shown that chlorophyll a and its epimer chlorophyll a' are chlorinated and hydroxyl‐ated during thin layer chromatography with silica gel plates. Hydroxylated chlorophyll a could not be chlorinated. Chlorinated and non chlorinated chlorophylls could be separated and determined by high performance liquid chromatography, because chlorophylls do not alter during this procedure. These findings support the assumption that Chi RC I is a preparation artifact. The extent of chlorination depends on chloride availability on the thin layer and on time. Chlorination and hydroyxlation do not take place under nitrogen atmosphere. The mechanism of chlorination during the thin layer chromatography procedure is discussed.
THE CONTROL OF METABOLISM BY BLUE LIGHT IN Acetabularia mediterranea—I. LIGHT DEPENDENCY AND EVIDENCE FOR POST‐TRANSCRIPTIONAL CONTROL OF UDPG PYROPHOSPHORYLASE AND PYRUVATE KINASE
Authors: Nickl Bernhard , Maass Ingrid , Schmid Rainer
Published: January 2008

Abstract— After a preculture in white light, Acetabularia mediterranea Lamouroux (=A. acetabulum (L.) Silva) was irradiated with either continuous red or blue light. In crude extracts, the specific activities of UDPG pyrophosphorylase(uridine–5′‐triphosphate: glucose 1‐phosphate uridylyltransfer‐ase EC 2.7.7.9) and pyruvate kinase(adenosine–5′‐triphosphate: pyruvate phosphotransferase EC 2.7.1.40) varied as a result of the different light qualities. In red light activities decreased to 40% and 60%, respectively, within 3 weeks of irradiation, while under blue light, if not preceded by a red irradiation, the activities remained unchanged. After prolonged red light, high enzyme activities were restored by blue light with a relatively rapid time course (3 to 4 days for completion) compared with the decrease in red light. A fluence‐response curve for the activation of UDPG pyrophosphorylase showed two phases with different sensitivities for blue light.

The blue light‐mediated increase in the activities of both enzymes was unaffected when the cell nucleus was removed before the beginning of the blue irradiation. The increase was inhibited by cycloheximide but not by chloramphenicol. Thus, functional cytosolic translation but not de novo transcription products are presumed to be required for the increase in specific enzyme activities in vivo.