bluuebunny/crossref_metadata_2025 huggingface dataset:
POLARIZED OPTICAL PROPERTIES OF PHYCOBILISOMES FROM Anabaena, Nostoc and Synechococcus
Authors: Frackowiak D. , Erokhina L. G. , Picard G. , Leblanc R. M.
Published: January 2008

Polarized absorption, photoacoustic, fluorescence excitation and fluorescence emission spectra of phycobilisomes were measured when embedded in polyvinyl alcohol films. The phycobilisomes were isolated from the following organisms:Anabaena cylindrica, Nostoc punctiformaandSynechococcus elongatus.The ratio of photoacoustic spectra to absorption was taken as a measure of thermal dissipation of excitation energy. The isotropic samples and those oriented by the film stretching were investigated. The stretching of the sample strongly influences the efficiency of excitation energy transfer occurring among biliproteins in phycobilisomes, as is seen from the dramatic changes in the fluorescence and thermal dissipation spectra. The effect of stretching the film depends on the shape of phycobilisomes and on the strength of interactions between biliproteins in phycobilisomes.
PARTIAL CHARACTERIZATION and LIGHT‐INDUCED REGULATION OF GTP‐BINDING PROTEINS IN Lemna paucicostata
Authors: Hasunuma Kohji , Furukawa Kazuhiko , Funadera Kanako , Kubota Mamoru , Watanabe Masakatsu
Published: January 2008

Binding of GTP‐binding proteins with [35S]GTP7S in the extract containing membrane components of Lemna paucicostata 441 was inhibited by red or far red light by 20 to 25%, but blue light showed no or little effect. The plant used for the preparation of the extract was subjected to single darkness for 8 h, as both red and far red light inhibit flowering. The extract treated with 1% Lubrol was fractionated by gel filtration. Four species of GTP‐binding proteins, GL1, GL2, GL3 and GL4 were detected with Km values 3, 7, 80 and 4 nM, respectively. GL1, GL2 and GL3 were ADP‐ribosylated by pertussis toxin. The extract activated by [35S]GTP‐γS in darkness, under red light or under far red light was treated with 1% Lubrol and subsequent gel filtration of the extracts made it possible to detect GTP‐binding protein with a small molecular weight only in an extract labeled in darkness. The reduction in the molecular weight of GTP‐binding protein from the larger molecule associated with the binding of [35S]GTPγS was confirmed by rechromatography of the larger molecule activated by [35S]GTPγS in darkness. The binding of GL2 and/or GL3 with [35S]GTPγS was suggested to be inhibited by red or far red light.
PHOTOSENSITIZING EFFICIENCIES, TUMOR‐ and CELLULAR UPTAKE OF DIFFERENT PHOTOSENSITIZING DRUGS RELEVANT FOR PHOTODYNAMIC THERAPY OF CANCER
Authors: Moan J. , Peng Q. , Evensen J. F. , Berg K. , Western A. , Rimington C.
Published: January 2008

AbstractSeveral parameters of the following dyes, all relevant as sensitizers for photochemotherapy of cancer, have been studied: Photofrin II (PII), hematoporphyrin (HP)‐di‐hexyl‐ether, HP‐di‐ethyl‐ether, tetra (3‐hydroxyphenyl) porphyrin, (3THPP), tetraphenyl porphine tetrasulphonate (TPPS4) aluminium phthalocyanine tetrasulfonate (A1PCTS), aluminium phthalocyanine (A1PC), chlorin e, (Chi e6) and merocyanine 540 (MC 540). The following parameters and features of these dyes were studied: (1) Tumor uptake in C3H mouse mammary carcinomas. (2) Skin/tumor concentration ratio in the same animal system. (3) Triton X‐114/H20 partition coefficients at different pH‐values. (4) Uptake of the dyes by human cells of the line NHIK 3025. (5) Relative fluorescence quantum yields of the dyes bound to cells. (6) Absorption‐, fluorescence‐excitation‐ and fluorescence‐emission spectra of the cell‐bound dyes. (7) Relative quantum yields for photoinactivation of cells after 18 h incubation with the dyes. (8) Relative quantum yields of photodegradation of the singlet oxygen trap 1,3‐diphenylisobenzofuran (DPBF) in cells after 18 h incubation with the dyes.

The following main conclusions were drawn: (1) 3THPP was the best and most selective tumor localizer of the dyes tested, followed by AIPCTS, TPPS4, PII and Chi e.,. (2) The Triton X‐114/H20 partition coefficient of most of the dyes decreased with increasing pH. (3) The cellular uptake of the dyes (18 h incubation in medium with 3% serum) increased with increasing Triton X‐114/H20 partition coefficient. (4) HP‐di‐hexyl‐ether had the highest quantum yields both for photoinactivation of cells and degradation of cell‐bound DPBF, followed by the other lipophilic porphyrins and Chi e6. The water‐soluble dyes TPPS4and AIPCTS had quantum yields of the order of ten times lower than those of the lipophilic porphyrins. (5) There was a clear correlation between the quantum yields for cell‐inactivation and those for photodegradation of DPBF, suggesting that the same reactive photoinduced species is involved in both processes. This suggestion was strengthened by the observation that DPBF reduced the quantum yield of cell inactivation. Thus, all the tested dyes seem to actviaa type II process. (6) All of the dyes, even the water‐soluble TPPS4and AIPCTS, are aggregated in aqueous solutions, and the cells bind both monomers and aggregates. (7) A significant fraction of the cell‐bound dyes was located close to tryptophan‐containing proteins. (8) Cell‐bound Chi e,6had the highest fluorescence quantum yield of the dyes.
LOCALIZATION OF MONO‐L‐ASPARTYL CHLORIN e6 (NPe6) IN MOUSE TISSUES
Authors: Aizawa Katsuo , Okunaka Tetsuya , Ohtani Takuzo , Kawabe Hirofumi , Yasunaka Yukari , O'Hata Susumu , Ohtomo Nobunari , Nishimiya Katsuaki , Konaka Chimori , Kato Harubumi , Hayata Yoshihiro , Saito Takashi
Published: January 2008

Abstract It is known that HpD is retained longer by malignant tissue than normal tissue and is therefore a useful material for photodynamic therapy (PDT). Currently, vigorous research is being conducted throughout the world to discover a new material which can have greater cancer cell affinity than hematoporphyrin derivative (HpD) and will be used effectively for PDT. Investigation has been conducted to determine the spectral characteristics and cancer cell affinity of NPe6, a recently developed material.

Structurally, a double bond on the D‐ring of the porphyrin ring of mono‐L‐aspartyl chlorin e6 (NPe6) has been reduced, thereby changing its spectral properties from that of HpD. This difference accounts for the stronger absorption bands in wavelengths longer than those of HpD. Furthermore, NPe6 in tumor showed stronger absorption at 660 nm than HpD. Absorption by hemoglobin (Hb) in the blood occurs at wavelengths in the range 500‐600 nm, thereby lowering light transmittance. A compound which has a strong absorption band at wavelengths longer than 600 nm and consequently is not affected by Hb will naturally be activated by light at a greater depth in tissue than compounds which do not share this characteristic. The localization of NPe6 in sarcoma and various internal organs was examined with an endoscopic spectrophotometer using an excimer dye laser. After 72 h i.v. NPe6 injection, the results indicate that NPe6 has 10 times greater uptake in malignant tissue cells than in normal organs. Based on the above observations, it was concluded that NPe6 could be effective for PDT if toxicity is low and that this compound has a high malignant tissue affinity.
SINGLET OXYGEN INVOLVEMENT IN PHOTOHEMOLYSIS SENSITIZED BY MEROCYANINE‐540 and ROSE BENGAL
Authors: Valenzeno Dennis Paul , Trudgen Julia , Hutzenbuhler Angela , Milne Mark
Published: January 2008

Merocyanine‐540 is currently in use in experimental protocols for the treatment of leukemia and neuroblastomas. The mechanism of cellular phototoxicity of this membrane binding sensitizer is unexplored. We have used sodium azide and deuterium oxide to examine the role of singlet oxygen in photomodification of cell membranes in a photohemolysis assay. The effects of these agents on the photomodification process were separated from the effects on the ion fluxes leading to lysis (lytic phase). Azide significantly inhibited photohemolysis sensitized by merocyanine‐540 or rose bengal. The inhibition was equal for both sensitizers. Azide had no effect on the lytic phase. Deuterium oxide significantly potentiated lysis with both sensitizers to approximately the same degree. There was little effect of deuterium oxide when added after illumination. The results indicate that singlet oxygen plays a significant role in membrane photomodification sensitized by both rose bengal and merocyanine‐540.
THE ELECTRON SPIN POLARIZATION OF THE DONOR‐TRIPLET STATE IN NATIVE and MODIFIED PHOTOSYNTHETIC REACTION CENTERS FROM
Authors: Wijk F. G. H. Van , Beijer C. B. , Gast P. , Schaafsma T. J.
Published: January 2008

The electron spin polarization (ESP) pattern of the donor‐triplet state (PR) of reaction centers (RC's) of the purple bacteriumRhodobacter(formerlyRhodopseudomonas) sphaeroidesR‐26 was investigated. δm =±1 triplet EPR spectra were recorded of unmodified RC's as well as of RC's from which Fe2+or ubiquinone was removed, or ubiquinone was substituted by menaquinone.

The relative amplitude of the Y peaks in the triplet EPR powder spectrum of PRdecreases when the temperature is increased from 8 K to 100 K in RC's with an intact quinone‐iron complex. This decrease is more pronounced when the primary ubiquinone is substituted by menaquinone. These observations provide further support for the hypothesis that the observed lineshape of the PRtriplet state EPR spectrum reflects the presence of a third electron spin, magnetically coupled to I‐in the P+I‐radical pair, as suggested by Van Wijk et al. (1986)(Photobiochem. Photobiophys. 11, 95–100). Our observations suggest that this phenomenon may be general in purple bacteria.
FREE RADICALS DETECTED BY ESR FROM PHENYLHEPTATRIYNE IN LIPOSOMES IRRADIATED WITH UV‐A
Authors: McRae D. , Yamamoto E. , Towers G. H. N.
Published: January 2008

Abstract—When irradiated with UV‐A liposome bilayers composed of distearoyl phosphatidylcholine and containing phenylheptatriyne produced a free radical signal detected by electron spin resonance spectroscopy. The spectrum contained one broad peak characterized by a linewidth of 19 G and a g value of 2.0017. The rate of formation of the signal amplitude was dependent upon light intensity, concentration of PHT within the bilayer and concentration of the PHT‐liposome suspension. Enhancement of the signal under an anaerobic atmosphere indicated a non‐photodynamic mechanism for free radical formation. Once formed however, the free radical was stable to the presence of oxygen and decayed very slowly with a half‐life of 8 h. Formation of the free radical species was demonstrated to be dependent upon a highly ordered lipid environment since incorporation of lysophosphatidylcholine, stearoyl which perturbs lipid packing, decreased the levels of the free radical species. On the other hand, when PHT was present in a liposome with a more fluid bilayer such as egg yolk phosphatidylcholine, the levels of free radical species were even lower. Conversely, the levels increased when cholesterol which increases lipid order, was incorporated into the egg yolk phosphatidylcholine liposomes. Cells ofE. coli, B, containing PHT, produced a similar free radical signal upon irradiation demonstratingin vivogeneration of free radicals from PHT.
MUTAGENIC AND RECOMBINOGENIC ACTION OF DNA MONOADDUCTS PHOTOINDUCED BY THE BIFUNCTIONAL FUROCOUMARIN 8‐METHOXYPSORALEN IN YEAST (Saccharomyces cerevisiae)
Authors: Averbeck D. , Averbeck S. , Cundari E.
Published: January 2008

Abstract—For the same furocoumarin 8‐MOP and the same total number of photoadditions, the genetic activity of DNA monoadducts and a mixture of mono‐ and biadducts photoinduced by the bifunctional furocoumarin 8‐methoxypsoralen (8‐MOP) is compared in the yeastSaccharomyces cerevisiae.In the presence of 8‐MOP, 405 nm irradiation induces only monoadducts, whereas 365 nm irradiation induces mono‐ and biadducts (interstrand cross‐links) in DNA. This is shown by heat denaturation‐renaturation experiments on calf thymus DNA treatedin vitroand by alkaline step elution analysis of DNA from treated yeast cells. For the same photobinding of tritiated 8‐MOP to DNA in diploid yeast, about 20 times higher doses are needed with 405 nm than with 365 nm irradiation. Re‐irradiation experiments reveal that part of the monoadducts induced by 8‐MOP and 405 nm irradiation can be effectively converted into DNA interstrand cross‐links by exposures to 365 nm radiation after washing‐out of unbound 8‐MOP molecules. 8‐MOP and 405 nm irradiation induce per lethal hit cytoplasmic “petite” mutations in yeast as efficiently as the monofunctional furocoumarin 3‐carbethoxypsoralen (3‐CPs) and 365 nm irradiation, both treatments being much more efficient than 8‐MOP and 365 nm irradiation. At equal survival, treatments with 8‐MOP and 405 nm radiation are clearly less efficient than treatments with 8‐MOP and 365 nm radiation for the induction of forward (CAN*) and reverse (HIS+) mutations in haploïd yeast and for the induction of mutations (ILV+) and genetically aberrant colonies including mitotic crossing‐over in diploid yeast. The two treatments are equally efficient for the induction of mitotic gene conversion. At equal photobinding of 8‐MOP, the monoadducts induced by 405 nm irradiation are found less effective than the mixture of mono‐and biadducts induced by 365 nm irradiation for the induction of cell killing, mutations and mitotic recombination.
TIME‐RESOLVED RESONANCE RAMAN SPECTRA OF THE PHOTOCYCLE INTERMEDIATES OF ACID AND DEIONIZED BACTERIORHODOPSIN
Authors: Chronister Eric L. , El‐Sayed M. A.
Published: January 2008

Abstract— The photocycle of bacteriorhodopsin (bR) and its perturbed forms are investigated by a time‐resolved resonance Raman study. These experiments were performed in the C=C stretching and in the fingerprint spectral regions for the acid blue, acid purple and deionized forms of bR.

The main observations are as follows: (1) isomerization of the retinal, from all‐trans to 13‐cis, occurs in native bR and in all of the acid and deionized perturbed bR species; (2) formation of the early intermediates (the K610 and L550 analogues) also occur in native bR and in all of the perturbed species; and (3) deprotonation of the protonated Schiff base (PSB), to give the M412 type intermediate, occurs in native bR, but is inhibited in all of the perturbed bR species on the time‐scale of the native bR photocycle.

The results show that isomerization alone is not a prerequisite for the PSB deprotonation process. The observed photocycle, initiated with retinal isomerization, is found to occur from all‐trans to 13‐cis in all of the perturbed forms of bR. In addition, the results imply that removal of the cations, of an increase in the hydrogen ion concentration, prevent only the PSB deprotonation process and not the formation of earlier cycle intermediates. Some attention is focused on the two blue forms of bR (acid and deionized) due to the fact that their ground‐state absorption maximum, unphotolyzed Raman spectra, and Raman spectra changes during the photocycle are all very similar. The similarities between the acid blue and deionized blue forms in the fingerprint region support previous suggestions that both blue species have nearly the same retinal active site.
TRIPLET LIFETIMES OF SOME FLAVINS
Authors: Fritz B. J. , Matsui K. , Kasai S. , Yoshimura A.
Published: January 2008

Abstract— Using flash photolysis the rate constants of the triplet decay at pH 7.0 (26°C) of 10‐hydroxyethyl‐isoalloxazine (2700 s−1), 2′‐deoxyRF (2300 s−1), 5′‐deoxyRF (3200 s−1), 8‐hydroxyRF (18 000 s−1) and 8‐aminoRF (28 000 s−1) have been measured. The results agree with other evidence that photochemical properties of flavins are influenced by the interaction of the sidechain with the isoalloxazine nucleus. In addition, our data on RF and FMN indicate that the triplet decay rates given in the literature for these compounds have to be corrected to 3200 s−1 (RF) and 4900 s−1 (FMN), respectively. The rate constants for the quenching of the triplet by ground state molecules for all above compounds are given.
LONG TERM DELAYED LUMINESCENCE OF VARIOUS OPTICAL COMPONENTS
Authors: Schmidt Werner
Published: January 2008

Abstract—Various interference absorption filters, high pass cutoff filters as well as a half mirror exhibit substantial long term delayed luminescence with halflives of approximately 0.5 s. Kinetics cannot be assigned to a specific order; the fluence response curves are complex and do not allow further analysis. The effect described might interfere with measurements of low light signals, particularly of biological samples.
PURIFICATION OF PHYTOCHROME FROM RYE BY FAST PROTEIN LIQUID CHROMATOGRAPHY
Authors: Ernst D. , Vojacek R. , Oesterhelt D.
Published: January 2008

Abstract. A rapid procedure for the purification of phytochrome from rye by fast protein liquid chromatography (FPLC) is described. A pre‐purification with Q‐Sepharose fast flow and hydroxylapatite fast flow is necessary in order not to exceed the total capacity of the Mono‐Q HR 5/5 column. The whole fractionation is finished within 24 h and yields an intact 124‐kDa phytochrome of high purity.
PHOTOSENSITIZERS: THERAPY AND DETECTION OF MALIGNANT TUMORS
Authors: Dougherty Thomas J.
Published: January 2008

Abstract. Advances in the use of photosensitizers for detection and treatment of malignant tumors during the previous reviews in this journal have been mainly in the areas of development of potentially useful new photosensitizers (e.g. phthalocyanines and chlorins), further understanding of the mechanisms of photodynamic therapy (PDT), and in dosimetry of light delivery in tissue. Perhaps the most significant advance during the past year has been the initiation of Phase III clinical trials of PDT vs standard therapy in treatment of superficial bladder cancer and obstructive endobronchial tumors. In the final analysis, only such clinical trials can determine the future of this new modality for cancer treatment.
LIGHT‐ABSORPTION AND ELECTRON‐TRANSPORT BALANCE BETWEEN PHOTOSYSTEM II AND PHOTOSYSTEM I IN SPINACH CHLOROPLASTS
Authors: MELIS Anastasios , Spangfort Michael , Andersson Bertil
Published: January 2008

Abstract—The distribution of absorbed light and the turnover of electrons by the two photosystems in spinach chloroplasts was investigated. This was implemented upon quantitation of photochemical reaction centers, chlorophyll antenna size and composition of each photosystem (PS), and rate of light absorptionin situ.In spinach chloroplasts, the photosystem stoichiometry was PSIIJPSIIα/PSIIβ/PSI= 1.3/0.4/1.0. The number (N) of chlorophyll (a+b) molecules associated with each PS was N(PSIIα)/N(PSIIβ)/N(PSI)=230/100/200, i.e. about 65% of all Chl is associated with PSII and about 35% with PSI. Light absorption by PSIIin vivois selectively attenuated at the molecular, membrane and leaf levels, (a) The rate of light absorption by PSII was only 0.85 that of PSI because of the lower rate of light absorption by Chlbas compared to Chla(approximately 80% of all Chlbin the chloroplast is associated with PSII). (b) The exclusive localization of PSIIαin the membrane of the grana partition regions and of PSI in intergrana lamellae resulted in a differential “sieve effect” or “flattening of absorbance” by the photosystems in the two membrane regions. Due to this phenomenon, the rate of light absorption by PSII was lower than that of PSI by 15‐20%. (c) Selective filtering of sunlight through the spinach leaf results in a substantial distortion of the effective absorbance spectra and concomitant attenuation of light absorption by the two photosystems. Such attenuation was greater for PSII than for PSI because the latter benefits from light absorption in the 700‐730 nm region.

It is concluded that, in spite of its stoichiometric excess in spinach chloroplasts, light absorption by PSII is not greater than that by PSI due to the different molecular composition of the two light‐harvesting antenna systems, due to the localization of PSII in the grana, and also because of the light transmission properties through the leaf. The elevated PSII/PSI reaction center ratio of 1.7 and the association of 65% of all Chl with PSII help to counter the multilevel attenuation of light absorption by PSII and ensure a balanced PSII/PSI electron turnover ratio of about 1:1.
PHOTOCHEMICAL REACTIONS OF CYTOSINE AND 5‐METHYLCYTOSINE WITH METHYLAMINE ANDn‐BUTYLAMINE
Authors: Shetlar Martin D. , Hom Kellie , Distefano Salvatore , Ekpenyong Kieran , Yang Jane
Published: January 2008

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 detectable at pH values as low as 5.
THE PHOTOTOXICITY OF PHENYLHEPTATRIYNE: OXYGEN‐DEPENDENT HEMOLYSIS OF HUMAN ERYTHROCYTES AND INACTIVATION OFEscherichia coli
Authors: Gong Hai‐Hua , Kagan Jacques , Seitz Rosemarie , Stokes Allison B. , Meyer Frederick A. , Tuveson R. W.
Published: January 2008

Abstract—Phenylheptatriyne (PHT) plus near‐ultraviolet light(320–400 nm; NUV) hemolyzed human erythrocytes in an oxygen dependent manner. When the phototoxicity of PHT plus NUV was tested with a series ofEscherichia colistrains carrying all four possible combinations of genes controlling excision proficiency (uvrA6 vs uvrA+) and catalase activity (HPII,katF vs katF*), the membrane was found to be an important lethal target. Consistent with this observation. PHT plus NUV did not induce histidine independent (his‐4+) mutations in the four tester strains (RT7h‐RT10h). Using tester strain RT10h, it was shown that there was no inactivation by PHT plus NUV in nitrogen. Results of experiments with anE. colifatty acid auxotroph (K1060) treated with PHT plus NUV are also consistent with membrane proteins being the chief targets for attack. Radicals were formed during the photolysis of PHT plus NUV in aqueous solutions, both in the presence of air and under nitrogen. Since PHT plus NUV did not hemolyze erythrocytes or inactivateE. colicells under nitrogen, these radicals are not cytotoxic.
PHOTOPHYSICAL PROPERTIES OF A CHLORIN, A POTENT SENSITIZER FOR PHOTOCHEMOTHERAPY
Authors: Brault Daniel , Vever‐Bizet Christine , Rougée Michel , Bensasson René
Published: January 2008

Abstract—Photophysical and photodynamic properties of a ehlorin type molecule derived from hydroxyethylvinyldeuteroporphyrin are presented. It photosensitizes singlet oxygen production as efficiently as mesotetraphenylporphin. The high absorptions of both its ground and triplet states in the red (660 nm) make it a potent photosensitizer which might act not only by photo‐oxidation via singlet oxygen but also by radicals produced via sequential biphotonic absorption.
A COMPARATIVE STUDY OF THE PHOTOCHEMISTRY OF THE NON‐STEROIDAL ANTI‐INFLAMMATORY DRUGS, NAPROXEN, BENOXAPROFEN AND INDOMETHACIN
Authors: MOORE DOUGLAS E. , CHAPPUIS PHILLIPE P.
Published: January 2008

Abstract—The photochemical reactivity of the non‐steroidal anti‐inflammatory drugs, naproxen and indomethacin, has been studied and compared with benoxaprofen, a similar compound of known cutaneous phototoxicity. Although indomethacin shows some phosphorescence at 77 K, flash photolysis at room temperature revealed only a weak photoionization process, and no photochemical reactivity was detected in steady state photolysis. Naproxen has strong fluorescence and phosphorescence, and in laser flash photolysis showed photoionization and a triplet state species in approximately equal yield. Naproxen and benoxaprofen produced singlet oxygen with similar quantum yield, as deduced from the sensitized rates of photooxidation of 2,5‐dimethylfuran. Naproxen underwent photodecarboxylation as detected by ESR‐spin trap experiments with 2‐methyl‐2‐nitrosopropane. The decarboxy‐naproxen radical combined readily with oxygen in aerated solution, and l‐(6‐methoxy‐2‐napthyl)ethanol and 2‐acetyl‐6‐methoxynaphthalene were formed as the oxidation products. In deaer‐ated solution, the major product was 2‐ethyI‐6‐methoxynaphthalene, with the alcohol also formed. In comparison, benoxaprofen also underwent decarboxylation, with much higher quantum yield, but the decarboxy‐benoxaprofen radical did not add oxygen. This difference in photoreactivity between naproxen and benoxaprofen, together with the much lower molar absorptivity of naproxen are the significant factors in relating to the differences in reported levels of clinical photosensitivity responses.
PICOSECOND FLUORESCENCE SPECTROSCOPY ON INCORPORATION PROCESSES OF HEMATOPORPHYRIN DERIVATIVE INTO MALIGNANT TUMOR CELLSin vitro
Authors: YAMASHITA MIKIO , TOMONO TAKAHISA , KOBAYASHI SHYUNSUKE , TORIZUKA KENJI , AIZAWA KATSUO , SATO TAKUZO
Published: January 2008

Abstract—By using a highly sensitive streak‐camera technique, we investigate incorporation processes of HpD into malignant tumor m‐KSA cellsin vitro.The picosecond decays of the total fluorescence spectra, the wavelength‐resolved fluorescence decays and the time‐resolved fluorescence spectra from HpD in the cells are measured as a function of the incubation time. The results show that the aggregate component of HpD which has a fast fluorescence lifetime of 100 ps and a red‐shifted band of ∼ 660 nm selectively accumulates more and more in the cells with the increase of the incubation time.
EQUILIBRIUM AMONG HEMATOPORPHYRIN‐DERIVATIVE COMPONENTS: INFLUENCE OF THE INTERACTION WITH CELLULAR STRUCTURES
Authors: BOTTIROLI GIOVANNI , RAMPONI ROBERTA
Published: January 2008

Abstract—Hematoporphyrin‐derivative (HpD) is a complex mixture of porphyrins in different aggregation states. The spectral analysis of HpD in aqueous solution shows the presence of monomeric species through the fluorescence emission spectrum and of both monomeric and aggregated species through the absorption spectrum.

The interaction with biopolymers and cellular components results in the appearance of new emission bands at 630 nm and in the640–670 nm spectral region which can be evidenced under suitable excitation conditions. Correspondingly, two new decay times (∼ 0.6 ns, and ∼ 3 ns), are observable. The new fluorescent species detected can be considered as the result of the hydrophobic effect induced by cellular structures on porphyrin aggregates.
THE DOSE‐RESPONSE RELATIONSHIP OF TUMORIGENESIS BY ULTRAVIOLET RADIATION OF 254 nm
Authors: Sterenborg H. J. C. M. , van der Putte S. C. J. , van der Leun J. C.
Published: January 2008

Abstract— Groups of albino hairless mice, Skh‐hrl, were exposed daily to UVC radiation from low pressure Hg arcs (Philips TUV 40W). These lamps emit predominantly radiation of 254 nm. Three groups of animals were used in the experiments, each receiving a different daily dose.

The results were described with the Weibull probability function. As in earlier studies with UVB. the tumor induction time was proportional to a power of the daily dose. The exponent turned out to be as low as ‐0.2. This implies that the induction time varied only a little with the daily dose. The average number of tumors per animal was proportional to a power of time. A sample of 73 tumors of at least 4 mm in diameter were investigated histologically. The large majority were classified as squamous cell carcinomas.

A comparison was made with the results of an earlier reported experiment with Westinghouse FS40 sunlamps. Throughout the whole range of daily doses used in the present experiment, UVC was less carcinogenic than UVB. An intriguing difference between the two types of radiation was that the tumors induced by UVC appeared much more scattered over the irradiated parts of the animals than the UVB‐induced tumors.
THE PHOTOACTIVE ANTIMICROBIAL PROPERTIES OF EUDISTOMINS FROM THE CARIBBEAN TUNICATE Eudistoma olivaceum
Authors: Hudson J. B. , Saboune H. , Abramowski Z. , Towers G. H. N. , Rinehart K. L.
Published: January 2008

Abstract— Five eudistomins, β‐carboline derivatives isolated from a Caribbean tunicate, were tested for phototoxicity against several viruses, bacteria, yeast, and mammalian cells. The five compounds showed varying degrees of UVA dependant phototoxicity (i.e. long wavelength UV dependant) against murine cytomegalovirus (MCMV), Sindbis virus (SV) and mouse 3T3 cells, although the relative order of potency was the same for these three organisms. Eudistomin N was the most active (approximately the same as the β‐carboline, harmine), while eudistomins M and O were moderately phototoxic, and H and I had little activity. To some degree the relative phototoxicity was correlated with fewer side chain substituents. A similar relative order of phototoxic potency was seen against phage T4, but in this case the magnitude of the effect was considerably reduced, in contrast to harmine. The antibacterial and antifungal activities were not correlated with antiviral effects, and some UVA‐independent activities were seen. Thus the eudistomins may possess different mechanisms of action against different organisms, depending upon the presence or absence of UVA.
PHOTOREVERSIBLE PROTON DISSOCIATION AND ASSOCIATION IN PEA PHYTOCHROME AND ITS CHROMOPEPTIDES
Authors: TOKUTOMI SATORU , YAMAMOTO KOTARO T. , FURUYAT MASAKI
Published: January 2008

Abstract— Effect of red‐light irradiation on the medium pH at 10d̀C was measured and compared among unbuffered solutions of the 121‐kDa native pea (Pisum sativum cv. Alaska) phytochrome and its 114‐ and 62‐kDa fragments in a red‐light‐absorbing form (Pr), all of which converted to far‐red‐light‐absorbing form (Pfr) on red‐light irradiation. Red‐light irradiation induced alkalinization in the solutions of the phytochrome and the fragments in the pH range 6.6‐7.2 and 6.2‐7.8, respectively. The amount of protons taken up by the 121‐kDa phytochrome was less than one half of that of the 114‐kDa fragment. Red‐light irradiation induced acidification in the solutions of the 114‐ and the 62‐kDa fragments above pH 7.8. In the solutions of the 121‐kDa phytochrome, however, the irradiation induced no pH change at pH 7.2‐8.2, and only a slight acidification at pH 8.2‐8.7, which may be ascribed to a small amount of contamination from the 114‐kDa fragment. All these red‐light‐induced pH changes were reversible following exposure to far‐red light. The 7‐kDa polypeptide(s) of the native 121‐kDa phytochrome, which is lacking in the 114‐kDa fragment, thus, prohibited proton transfer between phytochrome and the medium. A red‐light‐induced pH change was also measured in unbuffered solutions of the 39‐kDa fragment of the phytochrome and of the 114‐kDa fragment in the presence of 0.8 mM soyasaponin I. The 39‐kDa fragment showed partially photoreversible conversion between a spectral form having an absorption maximum at 659 nm (P659) and a bleached form, P***. The 114‐kDa fragment in the presence of the saponin showed a photoreversible conversion between P65V and Pb,. Exposure of P659 from the 39‐kDa fragment and from the 114‐kDa fragment in the presence of the saponin to red light, caused acidification of the medium in the pH range 6.8‐8.8 and 7.2‐9.0, respectively, but no change at pH 6.2‐6.8 and 6.4‐7.2, respectively. The acidification of the latter was reversible following a far‐red‐light irradiation, but that of the former was only partially photoreversible. Proton uptake of phytochrome was inhibited by tryptic degradation to the 39‐kDa fragment and also by the presence of the saponin. Only proton release was observed during the photoconversion from P659 and P***hl. It is suggested that a phytochrome molecule has possible site(s) for both proton release and for uptake and that the proton release reaction may be correlated to the photoconversion process(es) prior to the bleached intermediate (I***) of phytochrome.
SOME RELATIONSHIPS BETWEEN ULTRAVIOLET LIGHT AND HEME‐PROTEIN‐INDUCED PEROXIDATIVE LIPID BREAKDOWN IN LIPOSOMES, AS REFLECTED BY FLUORESCENCE CHANGES: THE EFFECT OF NEGATIVE SURFACE CHARGE
Authors: SZEBENI JANOS , TOLLIN GORDON
Published: January 2008

Abstract—The water soluble, photolabile nitrene precursor,azidonaphthalene–2,7‐disulfonic acid (ANDS) was encapsulated in small unilamellar, isoelectric (egg PC) or negatively charged (egg PC + dihexadecylphosphate) liposomes. The individual and combined effects of heme‐proteins and UV irradiation on the fluorescence of these vesicles under aerobic conditions were studied. Consistent with the catalytic action of heme‐proteins on lipid peroxidation and peroxide decomposition, addition of cytochrome c (positively charged) or catalase (negatively charged) to the vesicles elicited immediate formation of a fluorescence band at 470 nm, characteristic of Schiff bases that form from aldehyde byproducts of decomposing hydroperoxides. Ultraviolet irradiation of liposomes for 5 min caused no significant changes in the fluorescence spectrum, in spite of the radiolysis of ANDS inside the vesicles with consequent formation of nitrene radicals. When isoelectric vesicles were irradiated with UV light in the presence of cytochrome c or catalase, Schiff base formation was further increased by2–3 fold, which effect was not observed in the absence of internal ANDS, or in the presence of negative surface charge on the vesicles. These findings suggest that (a) UV irradiation, by itself, cannot trigger lipid decomposition even when it is assisted by photoproduced nitrene radicals, (b) there is a ternary synergism between UV light, heme‐proteins and nitrene radicals in promoting peroxidative lipid breakdown, and (c) negative surface charge inhibits the above synergism, which effect is unlikely to be due to electrostatic interaction between the vesicles and the protein or the ANDS.
TYPES I AND II SENSITIZED PHOTOOXIDATION OF AMINOACID BY PHTHALOCYANINES: A FLASH PHOTOCHEMICAL STUDY
Authors: Ferraudi G. , Arguello G. A. , Ali H. , VAN Lier J. E.
Published: January 2008

Abstract— In connection with the use of red light‐photosensitizers for photodynamic therapy, the redox reactivity of excited metallophthalocyanines (M = Al, Ga) was investigated by flash photolysis in order to establish whether photooxidations proceed by Foote's mechanisms I or II. Aminoacids (tryptophan, tyrosine) were seen to function as electron transfer quenchers of the excited phthalocyanines with rate constants 107k 104M‐1 s‐1. This was not the case of purines or ATP. The ability of the excited phthalocyanines to sensitize photooxidations by mechanisms I and II is discussed in terms of evaluated rate constants.
THERMAL REQUIREMENTS OF PHOTOSENSITIZED PYRIMIDINE DIMER SPLITTING
Authors: Kim Sang‐Tae , Rose Seth D.
Published: January 2008

Abstract— A cis, syn‐pyrimidine dimer (derived from thymine and orotate) covalently linked to 5‐methoxyindole has been studied as a mechanistic model of photosensitized pyrimidine dimer splitting. In this dimer‐indole, photoinitiated electron transfer to the dimer causes splitting in a manner that parallels the mechanism by which the DNA photolyases are thought to act. Dissolved in EPA (diethyl ether‐isopentane‐ethyl alcohol, 5: 5: 1, by vol) at room temperature, the dimer‐indole exhibited indole fluorescence quenching and underwent splitting upon irradiation at 300 nm. In an EPA glass at 77 K, however, no splitting was detectable. To distinguish the effects of temperature and immobilization, photolysis experiments were performed on PMM [poly(methyl methacrylate)] films containing dimer‐indole. In PMM at room temperature, dimer‐indole underwent splitting when irradiated at 300 nm, which indicated that immobilization per se was not responsible for the failure of dimer‐indole to split at low temperature. Furthermore, no splitting was observed when dimer‐indole was irradiated in PMM at 77 K. These results imply that a step following photoinitiated, intramolecular electron transfer from indole to dimer has an insurmountable activation barrier at 77 K. The mechanistic implications for the photolyases are considered.
ELECTRON TRANSFER REACTIONS OCCURRING UPON LASER FLASH PHOTOLYSIS OF PHOSPHOLIPID BILAYER SYSTEMS CONTAINING CHLOROPHYLL, BENZOQUINONE AND CYTOCHROME c‐I. NEGATIVELY‐CHARGED VESICLES*
Authors: Fang Yifei , Tollin Gordon
Published: January 2008

Abstract—In negatively‐charged lipid bilayer vesicles prepared in deionized water from egg phosphatidylcholine and 25 mol % of α‐eleostearic acid, and containing chlorophylla, benzoquinone, and cytochromec, primary electron transfer after a laser flash occurred principally from chlorophyll triplet to benzoquinone, and to a smaller extent from chlorophyll triplet to oxidized cytochromec. Several secondary electron transfer reactions occurred subsequent to this. The most rapid of these was electron transfer from reduced cytochromec, which was bound to the outer surface of the negatively‐charged vesicle, to chlorophyll cation radical (k= 3.9 times 103s‐1). Subsequent to this, the cation radical was reduced by benzoquinone anion radical (k= 1.6 times 102s‐1>) and bound oxidized cytochromecwas reduced by the remaining anion radical which was expelled into the aqueous phase by the negative charge on the vesicle surface. This latter reaction occurred at the membrane‐solution interface with an observed rate constant (k= 60 s‐1) two orders of magnitude smaller than cytochrome oxidation. Net reduced cytochromecwas produced in this process. The reduced cytochromecwas slowly reoxidized by benzoquinone (k= 17 s‐1) and the system was returned to its original state. When the vesicle system was made slightly basic by adding tris(hydroxymethyl)aminomethane, the rates of both the reverse electron transfer between chlorophyll cation radical and benzoquinone anion radical (k= 5 times 102s‐1) and the oxidation of reduced cytochrome c by chlorophyll cation radical (k= 9.4 times 103s‐1) were accelerated. The rate of reduction of oxidized cytochromecby benzoquinone anion radical remained approximately the same.
PHOTOCHEMISTRY OF AQUEOUS ADRIAMYCIN AND DAUNOMYCIN. A SPIN TRAPPING STUDY WITH17O ENRICHED OXYGEN AND WATER
Authors: Alegria Antonio E. , Riesz Peter
Published: January 2008

Abstract—Photolyses at 485 or 490 nm of air saturated, H2I7O enriched, aqueous solutions of adriamycin (ADR) in the presence of 5,5‐dimethyl‐l‐pyrroline‐l‐oxide (DMPO) produce a mixture of hydroxyl radical spin‐adducts, i.e. DMPO‐16OH‐ and DMPO‐17OH‐, as detected by electron spin resonance (ESR). DMPO‐17OH‐ was also observed during the irradiation at these same wavelengths of aqueous solutions of ADR or daunomycin (DA) containing DMPO and17O enriched oxygen. Therefore, the observed hydroxyl radical spin‐adducts derive from both water and gaseous oxygen. It is concluded from the measured relative spin‐adduct concentrations and from the enrichment fractions that most of the DMPO‐OH adducts originate from water. However, if anaerobic diluted solutions of ADR (200μ M) or DA (600μM)in the presence of DMPO (13mMand 27 mMrespectively) are irradiated at these same wavelengths no spin adduct is detected, indicating that oxygen is needed for the adduct formation, at these drug and spin trap concentrations. DMPO‐OH‐ is always observed if relatively high concentrations of either the drug (1.1–2.9 mM) or the spin trap(100–150 mM) are used in argon saturated solutions. A water photooxidation mediated mechanism is proposed in order to account for these results, analogous to previous observations in the photochemistry of other water soluble anthraquinone derivatives.
ANTIVIRAL PROPERTIES OF PHOTOSENSITIZERS*
Authors: Hudson J. B. , Towers G. H. N.
Published: January 2008

Abstract—We have studied the antiviral properties of three different groups of photo‐sensitizers,viz.(i) various furyl compounds; (ii) β‐carboline alkaloids; (iii) thiophenes and their acetylene derivatives. In general the antiviral potency of the furyl compounds correlated with their ability to produce DNA photoadducts.

Among the naturally occurring β‐carboline alkaloids, harmine was considerably more potent (in the presence of long wavelength UV radiation, UVA) than several other harmane‐related compounds. Slight alterations in chemical structure had profound effects on their antiviral activities. Harmine was shown to inactivate the DNA‐virus murine cytomegalovirus (MCMV) by inhibiting viral gene expression, although other targets may also exist. Several eudistomins, carboline derivatives isolated from a tunicate, were also photoactive against viruses.

Various plant thiophenes and polyacetylenes were studied in detail. These compounds also required UVA for antiviral activity, and some of them were extremely potent against viruses with membranes, e.g. α‐terthienyl, which showed significant activity at only 10‐5μg/ml. When MCMV had been treated with α‐terthienyl plus UVA, the virus retained its integrity and penetrated cells normally; but the virus did not replicate. More than 30 additional thiophenes have recently been evaluated, including many synthetic ones, and some of these are even more potent than a‐terthienyl. We believe that certain thiophenes possess potential therapeutic value and should be tested against model virus infections in animals.
RESONANCE RAMAN SPECTRA AND NORMAL MODE DESCRIPTIONS OF A BACTERIOCHLOROPHYLL a MODEL COMPLEX
Authors: Donohoe Robert J. , Frank Harry A. , Bocian David F.
Published: January 2008

Abstract— Resonance Raman (RR) spectra are reported for the bacteriochlorophyll a (BChl a) model complex, copper methylbacteriopheophorbide a (CuBPheo a). The spectra are acquired at a number of excitation wavelengths in the Qy+ Qx and B regions of the absorption spectrum. The RR data obtained for CuBPheo a are correlated to those previously reported for BChl a. The normal modes of the BChl structure are calculated by using the semiempirical quantum chemistry force field (QCFF/ PI) method of Warshel and Karplus [J. Am. Chem. Soc.94,5612–5625 (1972)]. The vibrational data are used in conjunction with the calculations to obtain a cohesive assignment for the normal modes of BChl a with frequencies between 1100 and 1700 cm‐1. The forms of the normal modes of BChl a are predicted to be different both from those of chlorophyll a and from those of porphyrins.
INTERACTIONS AND PHOTOREACTIVITY OF 5‐ALKOXYPSORALENS WITH THYMINE. A MODEL APPROACH
Authors: Décout Jean‐Luc , Huart Georges , Lhomme Jean
Published: January 2008

Abstract—In order to investigate the interactions and the photoreactions in solution between the thymine (thy) and the psoralen (Pso) rings, we have prepared model compounds Thy‐(CH2)n‐Pso in which two aromatic chromophores Thy and Pso are linked by flexible polymethylene chains of varying length (CH2)n. Two series of compounds were examined and compared as models for the two important drugs 5‐methoxypsoralen and 8‐methoxypsoralen. Results concerning the 5‐alkoxypsoralen series are reported here. In water, these model molecules exhibit intramolecular ring‐ring stacking interactions as indicated by hypochromism in the UV and by shielding of the protons in1H NMR spectroscopy. These interactions disappear in organic solvents. The photochemical properties of the models were examined in relation with their ground state interaction properties. Irradiation at 365 nm carried out at the usual concentrations (10‐2‐10‐3M)leads exclusively to a stereoselective dimerization involving the psoralen moieties of the models at the 3,4 double bonds. However, when operating at exceedingly low concentrations (2 × 10‐5M), the psoralen photodimerization is avoided and a highly regio and stereo‐selective psoralen thymine photoaddition is observed involving the 3,4 double bond of psoralen leading to thecisadduct. The same reaction occurs for all models under study being independent of the length of the (CH2)npolymethylene linking chain,n =2 to 6, 12 and of the solvent used. This is unambiguous proof for the highest intrinsic photoreactivity of the 3,4vsthe 4′,5′ double bond in 5‐alkoxy psoralen.
CONJUGATED DIENE FORMATION PROMOTED BY TRIPLET ACETONE ACTING UPON ARACHIDONIC ACID
Authors: Indig Guilherme L. , Campa Ana , Bechara Etelvino J. H. , Cilento Giuseppe
Published: January 2008

Abstract—Triplet acetone, whether generated from the decomposition of tetramethyldioxetane, enzym‐atically or by optical excitation, induces conjugated diene formation from micelle‐solubilized arach‐idonic acid as judged from the increase in A. Especially with optically generated triplet acetone, thiobarbituric acid reactive products could also be detected. When tetramethyldioxetane thermolysis was the source of triplet acetone, the activation energy for diene formation was the same as for thermolysis indicating that the latter is the rate determining step. Stern‐Volmer data indicate that the suppression of triplet acetone by arachidonic acid is diffusion controlled or almost so. Anthracene derivatives which are well known abstractors of energy from triplet acetone, decreased the rate of diene formation. Our results fully support the earlier inference that the observed lipid peroxidation is promoted by an excited species produced when substrates capable of enzymatic excitation are added to appropriate cells or organelles. Since lipid peroxidation efficiently generates excited species, the present results raise the possibility of an amplification mechanism and suggest that the effects produced by triplet carbonyls mimic those of ‘active oxygen species’.
PHOTOSENSITIZATION BY DIPORPHYRINS JOINED VIA METHYLENE BRIDGES
Authors: Kessel David , Dougherty T. J. , Truscott T. G.
Published: January 2008

Abstract— Photodynamic and biophysical properties of three porphyrin dimers joined by methylene bridges were examined. Fluorescence emission spectra and fluorescence lifetimes of the methylene‐linked dimers were similar to values obtained with porphyrin monomers. Singlet oxygen quantum yields were not significantly different when the three diporphyrins were compared. The diporphyrins were short‐acting tumor photosensitizers in vivo, and were rapidly cleared from plasma. Of the 3 diporphyrins examined, one was essentially ineffective as a sensitizer in vivo. This could not have been predicted from in vitro studies which indicated photodamage to membrane and mitochondrial loci. The methyiene‐linked diporphyrins were hydrophilic dyes (water/octanol distribution ratio =120–200) and bound mainly to plasma high‐density lipoprotein. In contrast, the more hydrophobic diporphyrin ester/ether fraction from HPD was a long‐persisting photosensitizer in vivo. Compared with hematoporphyrin, this hematoporphyrin derivative (HPD) fraction demonstrated a red‐shift in fluorescence emission and a shortened fluorescence lifetime. These comparisons suggest that ring‐ring interactions occur in the ester/ether‐linked diporphyrins from HPD, but not in the methyiene‐linked diporphyrins.
EFFECTS OF INTENSITY AND FLUENCE UPON DNA SINGLE‐STRAND BREAKS INDUCED BY EXCIMER LASER RADIATION
Authors: Chilbert M. A. , Peak M. J. , Peak J. G. , Pellin M. J. , Gruen D. M. , Williams G. A.
Published: January 2008

Abstract—A Xenon‐chloride excimer laser emitting energy at 308 nm was used to induce single‐strand breaks (SSBs, frank breaks plus alkali‐labile lesions as assayed by alkaline sucrose sedimentation techniques) in purified DNA fromBacillus subtilis. A fluence response study and a peak pulse intensity study were performed. At a pulse energy of 0.1 mJ/pulse, the radiation induced SSBs in a linear fashion (91 SSB/108Da per MJ/m2) to a maximum exprimental fluence of 1.28 MJ/m2. The pulse intensity study showed that there were no significant changes in DNA breakage (105 SSB/108Da) between 2.93 times 109and 5.86 times 1011W/m2(0.11 and 22.0 mJ/pulse) at a constant total fluence of 1.1 MJ/m2(27000 mJ dose). This study has verified and extended previous work by quantifying the yield of SSBs induced in DNA by this laser radiation.