bluuebunny/crossref_metadata_2025 huggingface dataset:
NUCLEAR FACTOR κB BINDING ACTIVITY IN MOUSE L1210 CELLS FOLLOWING PHOTOFRIN II‐MEDIATED PHOTOSENSITIZATION
Authors: Ryter Stefan W. , Gomer Charles J.
Published: January 2008

Clinical photodynamic therapy (PDT) uses the photosensitizer photofnn II to produce singlet molecular oxygen and other reactive oxygen intermediates for localized tumor tissue cytotoxicity. In this report, we show that PDT enhances the DNA binding activity of nuclear factor kappa B (NFkB), a transacti vator of cytokine gene expression. Photosensitization following a 16 h incubation of photofrin II induced NFkB binding activity in mouse leukemia L1210 cells 10‐fold above that observed in exponentially growing cultures. Serum starvation, as well as drug‐alone and light‐alone controls, elevated basal NFkB binding activity two‐ to three‐fold. Upstream stimulatory factor binding activity was not modulated by any of the cell treatments and was used to standardize gel mobility shift data. This study identifies porphynn‐mediated PDT as an inducer of NFkB binding activity, extending recent findings that NFkB activation is a general response to oxidative stress.
BOOK REVIEW
Authors: Song Pill‐Soon
Published: January 2008

Frontiers of Photobiology. Edited by Akihiro Shima, Masa‐mitsu Ichihasi, Yoshisada Fujiwara and Hiraku Takebe
8‐METHOXYPSORALEN PLUS UVA INDUCES THE 72 kDa HEAT SHOCK PROTEIN IN ORGAN‐CULTURED NORMAL HUMAN SKIN
Authors: Muramatsu T. , Yamashina Y. , Tada H. , Kobayashi N. , Yamaji M. , Ohno H. , Shirai T. , Takahashi A. , Ohnishi T.
Published: January 2008

Abstract The proteins induced by heat and other stressors, called heat shock proteins (HSP) or stress proteins, are considered to play a general role in protection from cellular injury. Exposure to UVA (320400 nm) following application of 8‐methoxypsoralen (8‐MOP), termed PUVA is commonly used in the field of dermatology. In order to understand the induction of HSP in PUVA‐treated human skin, indirect immunofluorescence using a monoclonal antibody specific for the 72 kDa HSP (HSP 72) was carried out in organ‐cultured normal human skin that was treated with PUVA. When the organ‐cultured skin was treated at 37°C for 1 h with 8‐MOP at a final concentration of 10 or 100 μg/mL and exposed to UVA (51.3 kJ/m2), nuclear immunofluorcscence of HSP 72 was detected in the epidermal cells 12 h after UVA irradiation. In contrast, the induction of HSP 72 was not detected either by UVA irradiation or 8‐MOP treatment. These results suggest that PUVA treatment is one of the stressors for human skin, and DNA damage caused by PUVA induces HSP 72.
NORMAL BRAIN TISSUE RESPONSE TO PHOTODYNAMIC THERAPY USING ALUMINUM PHTHALOCYANINE TETRASULFONATE IN THE RAT
Authors: Leach M. W. , Khoshyomn S. , Bringus J. , Autry S. A. , Boggan J. E.
Published: January 2008

Abstract— The effects of photodynamic therapy (PDT) on normal brain tissue and depth of brain necrosis were evaluated in rats receiving 2.5 mg/kg aluminum phthalocyanine tetrasulfonate. Twenty‐four hours later brains were irradiated with 675 nm light at a power density of 50 mW/cm2 and energy doses ranging from 1.6 to 121.5 J/cm2. Brains were removed 24 h after PDT and evaluated microscopically. When present, brain lesions consisted of well‐demarcated areas of coagulation necrosis. When plotting the depth of necrosis against the natural log of energy dose, the data fit a piecewise linear model, with a changepoint at 54.6 J/cm2 and an x intercept of 7.85 J/cm2. The slopes before and after the changepoint were 2.04 and 0.21 mm/In J cm‐2, respectively. The x intercept suggests a minimum light dose below which necrosis of normal brain will not occur, whereas the changepoint indicates the energy density corresponding to an approximate maximum depth of necrosis.
ACTION SPECTRA FOR INHIBITION OF HYPOCOTYL GROWTH OF WILD‐TYPE PLANTS AND OF THE hy2 LONG‐HYPOCOTYL MUTANT OF Arabidopsis thaliana L.
Authors: Goto Nobuharu , Yamamoto Kotaro T. , Watanabe Masakatsu
Published: January 2008

Abstract— An analysis was made by action spectroscopy, using the Okazaki Large Spectrograph, of the inhibition of hypocotyl elongation of wild‐type plants and the hy2 mutant of Arabidopsis thaliana. Two day old etiolated seedlings were irradiated for 8 h with monochromatic light and left in the dark for 16 h before measurement of hypocotyl length. Spectrophotometric measurement showed that levels of phytochrome in the etiolated tissue of the hy2 mutant were less than 9% of those in the wild type. The action spectra of the wild type looked like those of high irradiance response and showed peaks at 375, 450, 625 and 725 nm, whereas the action spectra of hy2 showed only the peaks at 375 and 450 nm. Monochromatic light of wavelengths longer than 500 nm had no significant inhibitory effects on hy2 plants. Blue and UV‐A light were about five times more effective in the wild type than in hy2 plants. Severe inhibitory effects were observed with UV‐B light. It is concluded that inhibition of the growth of the hypocotyl involves combined actions of phytochrome and a putative blue/UV‐A photoreceptor(s).
FLUORESCENCE LIFETIME AND QUENCHING STUDIES OF SARCOPLASMIC RETICULUM CA2+ ‐ADENOSINE‐5′‐TRIPHOSPHATASE*
Authors: Ferreira Sergio T.
Published: January 2008

Abstract— Different classes of tryptophan residues in sarcoplasmic reticulum calcium‐ATPase were investigated with respect to their exposure to quenchers and sensitivity to high‐affinity calcium binding to the ATPase. The charged quenchers, iodide and cesium, produced only slight quenching of ATPase fluorescence, whereas noncharged acrylamide and notably oxygen produced significant quenching. This finding gives support to the proposed location of most of the tryptophan residues of the ATPase in transmembrane domains of this protein (MacLennan et al., 1985, Nature316r, 696–700). Among the different quenchers tested, oxygen quenching alone was sensitive to calcium binding to the ATPase, indicating that oxygen quenched tryptophan residues located in regions of the ATPase molecule which undergo conformational changes upon calcium binding. Time‐resolved oxygen quenching data were analyzed with a recently described model that takes into account the existence of two different classes of emitters in the ATPase (Ferreira and Verjovski‐Almeida, 1991, J. Lumin. 48, 430–434): a short‐lived blue‐shifted exponential component plus a long‐lived red‐shifted continuous lifetime distribution. Oxygen quenching of the single‐exponential lifetime component was found to be insensitive to calcium, whereas quenching of the distributed lifetime component was significantly (ca 25%) enhanced by calcium binding. The different sensitivities of the two tryptophan classes to calcium binding to the ATPase are interpreted in terms of the proposed location of tryptophan residues in relation to the calcium transport sites in the ATPase molecule.
PHTHALOCYANINE‐INDUCED PHOTOHEMOLYSIS: STRUCTURE‐ACTIVITY RELATIONSHIP AND THE EFFECT OF FLUORIDE
Authors: Ben‐Hur E. , Malik Z. , Dubbelman T. M. A. R. , Margakon P. , Ali H. , van Lier J. E.
Published: January 2008

Abstract— Phthalocyanine (Pc) containing AI, Ga or Zn as central metal ligand and substituted with a varying number of sulfonic acid residues as well as additional benzene rings were synthesized and their photodynamic activity was assayed using photohemolysis of human erythrocytes as an endpoint. The Pc derivatives vaned > 300‐fold in their photodynamic activity. Activity corrclated with binding of the dye to the cell, with the exception of some of the amphiphilic dyes where cell uptake was an order of magnitude higher than expected from the observed activity. Fluoride was shown to inhibit AIPcSn‐induccd photohemolysis. This effect occurred also with other AlPc and GaPc derivatives, but the concentration of F required to slow photohemolysis by a factor of two (Ki) varied between 4 μM and 10 mM. Fluorescence spectral studies indicated complex formation between F− and the dye, which was stronger for AlPc than GaPc derivatives. Ultrastructural studies using scanning electron microscopy showed that the photosensitized cells were converted to spherocytes and that F− prevented this to a large extent.
THE EFFECTS OF THROMBOXANE INHIBITORS ON THE MICROVASCULAR AND TUMOR RESPONSE TO PHOTODYNAMIC THERAPY
Authors: Fingar Victor H. , Siegel Kimberly A. , Wieman T. Jeffery , Doak Karola Weber
Published: January 2008

Abstract— Vascular stasis and tissue ischemia are known to cause tumor cell death in several experimental models after photodynamic therapy (PDT); however, the mechanisms leading to this damage remain unclear. Because previous studies indicated that thromboxane release is implicated in vessel damage, we further examined the role of throm‐boxane in PDT. Rats bearing chondrosarcoma were injected with 25 mg/kg Photofrin® (intravenously) 24 h before treatment. Light (135 J/cm2, 630 nm) was delivered to thc tumor area after injection of one of the following inhibitors: (1) R68070: a thromboxane synthetase inhibitor; (2) SQ‐29548: a thromboxane receptor antagonist; and (3) Flunarizine: an inhibitor of platelet shape change. Systemic thromboxane levels were determined. Vessel constriction and leakage were evaluated by intravital microscopy. Tumor response was assessed after treatment. Thromboxane levels were decreased more than 50% with SQ‐29548 as compared to controls. Thromboxane levels in animals given R68070 and Flunarizine remained at baseline levels. SQ‐29548 and R68070 reduced vessel constriction compared to controls, while Flunarizine totally prevented vessel constriction. R68070 and SQ‐29548 inhibited vessel permeability compared to PDT controls; Flunarizine did not. Animals given these inhibitors showed markedly reduced tumor cure. These results indicate that the release of thromboxane is linked to the vascular response in PDT.
In situ FLUORESCENCE SPECTROSCOPIC STUDIES ON BOVINE CORNEA
Authors: Uma L. , Balasubramanian D. , Sharma Yogendra
Published: January 2008

Abstract— The cornea is a transparent ocular tissue and its transparency is thought to be a result of intramolecular interactions and the supramolecular organization of its protein constituents. We have studied the intrinsic fluorescence properties of intact bovine corneas and compared these with that of the opaque sclera. It was observed that with increasing excitation wavelengths the emission maxima shifted toward the red edge exhibiting the phenomenon of red edge excitation shift, which is indicative of immobilization of the constituent fluorophores. The magnitude of the shift increased after photodamage by irradiation at 295 nm. Many of the spectral characteristics of the cornea are shown to be due to its proteoglycans, which show surprisingly significant red edge excitation shift in solution.
KINETIC STUDIES ON THE STABILIZATION OF THE PRIMARY RADICAL PAIR P680+ Pheo‐ IN DIFFERENT PHOTOSYSTEM II PREPARATIONS FROM HIGHER PLANTS*
Authors: Bernarding J. , Eckert H.‐J. , Eichler H. J. , Napiwotzki A. , Renger G.
Published: January 2008

Abstract— The stabilization of the primary radical pair P680+ pheophytin (Pheo)‐ through rapid electron transfer from Pheo to the special plastoquinone of photosystem II (PS II), QA, was analyzed on the basis of time‐resolved (40 ps) UV‐absorption changes detected in different PS II preparations from higher plants. Lifetime measurements of1Chi* fluorescence by single photon counting and a numerical analysis of the redox reactions revealed (1) at exciton densities required for light saturation of the stable charge separation, annihilation processes dominate the excited state decay leading to very similar lifetimes of 1Chi* in systems with open and closed reaction centers and (2) the difference of absorption changes induced by actinic flashes of comparatively high photon density in samples with open and photochemically closed reaction centers, respectively, provides a suitable measure of the rate constant of QA formation. Conclusion 2 was confirmed in PS II membrane fragments by measurements at three wavelengths (280 nm, 292 nm and 325 nm) where the difference spectrum of Q‐A formation exhibits characteristic features. The numerical evaluation of the experimental data led to the following results: (1) the rate constant of Q‐A formation was found to be (300 ± 100 ps)‐1 in PS II membrane fragments and PS II core complexes deprived of the distal and proximal antenna and (2) an iron depletion treatment of membrane fragments does not affect these kinetics. The implications of these results are briefly discussed in terms of the PS II reaction pattern.
PHARMACOKINETIC AND TISSUE DISTRIBUTION STUDIES OF THE PHOTOSENSITIZER bis(DI‐ISOBUTYLOCTADECYLSILOXY)SILICON 2,3‐NAPHTHALOCYANINE (isoBOSINC) IN NORMAL AND TUMOR‐BEARING RATS
Authors: Zuk Maria M. , Rihter Boris D. , Kenney Malcolm E. , Rodgers Michael A. J. , Kreimer‐Birnbaum Martha
Published: January 2008

Abstract Bis(di‐isobutyl octadecylsiloxy)silicon 2,3‐naphthalocyanine (isoBOSINC) is a representative of a group of naphthalocyanine derivatives with spectral and photophysical properties that make them attractive candidates for photodynamic therapy (PDT). Tissue distributions were studied in normal and in tumor‐bearing rats as a function of time following intravenous injection of isoBOSINC as a suspension in 10% Tween 80 in saline. The dose studied was 0.25 mg/kg of body weight. The compound isoBOSINC was isolated from several tissues and organs, as well as tumors and peritumoral muscles and skin, and quantitated by a high‐performance liquid chromatographic technique. The tumor model, an N‐(4‐[5‐nitro‐2‐furyl)‐2‐thiazolyl)formamide (FANFT)‐induced urothelial cell carcinoma, was transplanted into the hind legs of Fischer 344 rats. The dye was retained in tumors at higher concentrations than in all tissues and organs examined, except for spleen and liver. The highest concentration ratio of dye in tumor versus peritumoral muscle (24.5) occurred 9 h after injection. Serum clearance of isoBOSINC showed similar kinetic behavior for both groups of rats, with a t1/2 of elimination of ∼ 10 h. At 7 and 14 days postinjection, the levels of dye found in testes were generally higher than in most other tissues, except spleen and liver. Concentrations of isoBOSINC were either very low or not detectable in rat brain. Trace amounts of the dye were excreted in the urine, and by day 14 approximately 17% of the dose was accounted for in the feces. The significant levels of the drug in tumors, as well as the excellent ratios of tumor‐to‐muscle concentration observed, have promising implications for PDT of tumors.
PENETRATION POTENCY OF TOPICAL APPLIED δ‐AMINOLEVULINIC ACID FOR PHOTODYNAMIC THERAPY OF BASAL CELL CARCINOMA *
Authors: Szeimies Rolf‐Markus , Sassy Tarek , Landthaler Michael
Published: January 2008

Abstract Penetration potency of δ‐aminolevulinic acid (ALA) was studied by examining fluorescence of endogenous protoporphyrin IX in different histological types of basal cell carcinoma. Ten basal cell carcinomas were coated with an ointment containing 10% ALA prior to excision; five served as controls. Tumors were excised either 4 h or 12 h after application of ALA using a modified Mohs’micrographic surgical technique. Horizontal sections were cut from deep dermis to tumor surface and examined under a fluorescence microscope. After 4 h of application, only skin appendages demonstrated fluorescence typical of protoporphyrin IX. After 12 h, fluorescence was detectable in tumor cells in deep dermis. The five controls revealed no fluorescence at any site. These results may confirm the high penetration potential of topically applied ALA and its usefulness in photodynamic therapy. For tumors penetrating to deep dermis, an application time of more than 4 h seems necessary, at least when hydrophilic solvents for ALA are used.
LIGHT‐MEDIATED CYCLIZATION OF (E)‐3‐(5‐[6‐HYDROXY‐7‐METHOXY] BENZOFURANYL)PROPENOIC ACID, A WATER‐SOLUBLE PRECURSOR OF 8‐METHOXYPSORALEN
Authors: Mohammad Taj , Morrison Harry
Published: January 2008

The title compound is a stable, water‐soluble “pro‐drug” for 8‐methoxypsoralen, which converts to psoralen upon photolysis with UVA light. The process involves the photolytic formation of acisisomer that lactonizes in a dark reaction.
HOMOLOGY AT THE AMINO ACID LEVEL BETWEEN PLANT PHYTOCHROMES AND A REGULATOR OF ASEXUAL SPORULATION IN Emericella (=Aspergillus) nidulans
Authors: Grifith Gareth W. , Jenkins Gareth I. , Milner‐White E. James , Clutterbuck A. John
Published: January 2008

–Protein sequence comparison between the N‐terminal regions of the BRLA (bristle A) protein of the ascomycete fungus Aspergillus nidulans and a number of plant phytochromes has demonstrated a moderate level of sequence similarity. The region of similarity corresponds to the phytochrome domains believed to be responsible for photoreception and which undergo light‐induced conformational changes, although a putative chromophore‐binding site is not evident. Over 22% of residues are conserved and 24% conservatively substituted between residues 1 and 272 of BRLA and the N‐terminal domains of Type 1 phytochromes from dicotyledonous species. A lower level of similarity, but over the same region, is observed in comparison with a wider range of phytochromes. Given the known role of BRLA as a transcriptional activator involved in conidiation, and the red/far‐red reversible photoregulation of this developmental process, the similarity with phytochromes may be significant.
ADVENTITIOUS INTERCONVERSION OF cis‐ AND trans‐UROCANIC ACID BY LABORATORY LIGHT
Authors: Hug Daniel H. , Hunter John K.
Published: January 2008

Urocanic acid (UCA) is a chromophore in the stratum corneum. Ultraviolet radiation (ultraviolet B) has been shown to suppress mammalian cell‐mediated immunity. The photoisomerization of trans‐UCA to cis‐UCA was proposed as the initiator of the suppression process. Cis‐urocanic acid has been demonstrated to suppress immunity by a variety of experiments. Investigators should be aware that laboratory illumination may be capable of interconverting trans‐UCA and cis‐UCA during experimental manipulations. This possible inadvertent contamination of one isomer by the other may influence results. We demonstrated that fluorescent lamps, daylight, sunlight and incandescent lamps were able to bring about isomerization. Window glass and container materials of plastic and clear glass did not filter out effective wavelengths, but three commercial plastic diffusers on fluorescent fixtures prevented the isomerization. Because the molar extinction coefficient (ɛ) for cis‐UCA is less than that of trans‐UCA, we have exposed 0.1 mMtrans‐UCA to ambient light and monitored the change in absorbance. A method is given to calculate the percentage of trans and cis isomers from the absorbance at 277 nm when the initial purity and absorbance are known. Using this procedure, we validated the molar extinction coefficient of cis‐UCA.
THE ORIGIN OF THE RED‐SHIFTED ABSORPTION MAXIMUM OF THE M412 INTERMEDIATE IN THE BACTERIORHODOPSIN PHOTOCYCLE
Authors: Gat Y. , Sheves M.
Published: January 2008

The factors that red shift the absorption maximum of the retinal Schiff base chromophore in the M412 intermediate of bacteriorhodopsin photocycle relative to absorption in solution were investigated using a series of artificial pigments and studies of model compounds in solution. The artificial pigments derived from retinal analogs that perturb chromophore‐protein interactions in the vicinity of the ring moiety indicate that a considerable part of the red shift may originate from interactions in the vicinity of the Schiff base linkage. Studies with model compounds revealed that hydrogen bonding to the Schiff base moiety can significantly red shift the absorption maximum. Furthermore, it was demonstrated that although s‐trans ring‐chain planarity prevails in the M412 intermediate it does not contribute significantly (only ca 750 cm−1) to the opsin shift observed in M412. It is suggested that in M412, the Schiff base linkage is hydrogen bonded to bound water and/or protein residues inducing a considerable red shift in the absorption maximum of the retinal chromophore.
PHOTOREGULATION OF α‐CHYMOTRYPSIN ACTIVITY IN ORGANIC MEDIA: EFFECTS OF BIOIMPRINTING
Authors: Willner Itamar , Lion‐Dagan Mazzi , Rubin Shai , Wonner Johann , Effenberger Franz , Bäuerle Peter
Published: January 2008

Abstract α‐Chymotrypsin exhibits photoswitchable activities in an organic solvent after covalent modification of the protein backbone with thiophenefulgide active ester (2). The thiophenefulgide‐modified α‐chymotrypsin exhibits reversible photoisomerizable properties between states (3)‐E and (3)‐C. The modified α‐chymotrypsin, where nine lysine residues are substituted by thiophenefulgide units, retains 60% of the activity of the native enzyme. The activities of thiophenefulgide‐modified α‐chymotrypsin toward esterification of N‐acetyl‐L‐phenylalanine (4) by ethanol in cyclohexane are controlled by the configuration of the attached photoisomerizable component and by prior bioimprinting of the protein backbone with the reaction substrate (4). The esterification of (4) in cyclohexane using bioimprinted (3)‐C is two‐fold faster than in the presence of (3)‐E. In the presence of a nonbioimprinted enzyme, esterification of (4) by (3)‐C is five‐fold faster than with (3)‐E. The activity of bioimprinted (3)‐E toward esterification of (4) is 4.5‐fold higher than that of nonbioimprinted (3)‐E. Switchable cyclic esterification of (4) is accomplished by sequential photoisomerization of the thiophenefulgide‐modified α‐chymotrypsin between states (3)‐C and (3)‐E.
THE EFFECTS OF ULTRAVIOLET C ON in vitro NUCLEOSOME ASSEMBLY AND STABILITY
Authors: Matsumoto Hideki , Takakusu Akira , Ohnishi Takeo
Published: January 2008

Abstract The effects of ultraviolet C (UVC) irradiation on nucleosome assembly and its stability were investigated quantitatively using an in vitro nucleosome assembly system comprising a plasmid DNA of pBR322 and core histones isolated from rat ascites hepatoma cells. Nucleosomal formation was estimated by analyzing the resulting DNA supercoils. When UVC‐irradiated (3000 J/m2) DNA was used as a substrate for the nucleosome assembly system, the nucleosomal formation efficiency was reduced by half compared with nonirradiated DNA. On the other hand, when the reconstituted nucleosomes (minichromosomes) on the nonirradiated DNA were irradiated with UVC (3000 J/m2), about half each were disrupted and retained. These results indicate that it is difficult for UV‐damaged DNA regions to supercoil around the histone octamers to form nucleosomes and that the histone octamers in the UV‐damaged nucleosomes tend to be dissociated from DNA.
NEW PHTHALOCYANINES FOR PHOTODYNAMIC VIRUS INACTIVATION IN RED BLOOD CELL CONCENTRATES
Authors: Rywkin S. , Ben‐Hur E. , Malik Z. , Prince A. M. , Li Y.‐S. , Kenney M. E. , Oleinick N. L. , Horowitz B.
Published: January 2008

Abstract Cationic phthalocyanines with either aluminum or silicon as the central metal were evaluated for their ability to inactivate viruses in red blood cell concentrates (RBCC) photodynamically. In addition, the virucidal potential of a substituted anionic phthalocyanine, aluminum dibenzodisulfophthalocyanine hydroxide (AlN2SB2POH) was evaluated and compared with that of the much studied anionic aluminum tetrasulfophthalocyanine hydroxide (AIPcS4OH). Based on the rate of inactivation of the lipid‐enveloped vesicular stomatitisvirus (VSV), the viruci dal potential of these phthalocyanines was: HOSiPCOSi(CH3)2(CH2)3N+(CH3)3I‐ (Pc 5) = SiPC[OSi(CH3)2‐(CH2)3N+(CH3)3I‐]2 (Pc 6) > AIPCOSi(CH,)2(CH2)˜N+(CH3)2(CH˜)11CH3I‐ (Pc 21) = A1N2SB2POH = AlPcS4 > HOSiPc[OSi(CH3)2(CH2)3N+(CH3)2(CH2)11CH31–]2(Pc 14) > AIPcOSi(CH3)2(CH2)3N+(CHS)3I‐ (Pc 2). Phthalocy anine ligand 14 and Pc 21 are new phthalocyanines, made by quaternizing known amino analogues. Compared to VSV, the rate of inactivation of Sindbis virus (another model lipid‐enveloped virus) was identical when treated in red blood cells (RBC) with Pc 5 and slightly higher when treated with Pc 6 and AlPcS4OH. Treatment of RBCC containing cell‐free human immunodeficiency virus (HIV‐1) with Pc 5 or AlPcS4OH required 15 min of irradiation to inactivate (>5 log10 reduction) the virus. The extent of HIV‐1 inactivation with AlN2SB2POH was 3.7 log10 after 60 min of red light exposure. The RBC integrity after photosensitization was measured by the ability of the cells to bind to plates coated with poly‐L‐lysine, (which reflects the retention of the RBC surface negative charges) and hemolysis of the cells over a 7 day storage period. The RBC damage using these criteria was most pronounced with Pc 5 and Pc 6 but could be reduced when treatment was in plasma instead of buffer. These data indicate that lipid‐enveloped viruses differ in their sensitivity to phthalocyanine photosensitization. Therefore, for virus sterilization of RBCC for transfusion the ability to inactivate human pathogenic viruses completely will have to be evaluated for each virus. The cationic Pc 5 appears to be a potentially useful virucidal agent.
PSORALEN‐OLEFIN PHOTOPRODUCI'S: FIRST OBSERVATION OF A PHOTO‐ENE REACTION
Authors: Semin David J. , Winkler Paul C. , Rowlen Kathy L.
Published: January 2008

Abstract Methyl‐substituted psoralens (4′‐(hydroxymethyl)‐4,5′,8‐trimethylpsoralen and 4,5′,8‐trimethylpsoralen) are found to yield an ene product as well as the expected [2+2] cycloaddition product from photochemical reaction with simple olefins. As determined by absorbance, liquid chromatography‐mass spectrometry and nuclear magnetic resonance, both products are formed at the pyrone side of the respective psoralen. The product distribution is dependent on olefin concentration as well as the nature of the olefin. In deoxygenated solutions, cyclic olefins form as much as 50% ene product, while unsubstituted straight‐chain olefins form as little as 3%. In oxygenated solutions, the product distribution is strongly affected by singlet oxygen.
PHOTOREAaIVITY OF CHLORAMPHENICOL in vitro AND in vivo
Authors: Vries Henk de , Hemelaar Peter J. , Gevers Alice C. M. , Van Henegouwen Gerard M. J. Beyersbergen
Published: January 2008

Abstract The negative side effects of chlorarnphenicol (CAP) mostly involve blood dyscrasias (e.g. irreversible nondose‐dependent aplastic anemia), allergic skin reactions and eye damage. To learn the cause of these side effects, most research focuses on metabolically formed nitroso‐ and hydroxylamino derivatives in the predisposed patient. In previous investigations it was demonstrated that photochemical decomposition of CAP in vitro by UV‐A leads to formation of p‐nitrobenzaldehyde (pNB), p‐nitrobenzoic acid (pNBA) and p‐nitrosobenzoic acid (pNOBA); the latter comprises up to 45 mol% of the starting amount of CAP. Incubation of these photoproducts in rat blood showed that pNB and pNOBA rapidly react and that PNBA is stable under these conditions. Reaction products from pNB (half‐life 1.7 min) proved to be pNBA and p‐nitrobenzyl alcohol (pNBOH) while pNOBA (half‐life 3.7 min) was converted into p‐aminobenzoic acid (pABA). Exposure of CAP in rat blood to UV‐A yielded the same end products: pNBA, PABA and pNBOH. To estimate the amount of oxidative stress generated in vivo by these compounds, the ability to form methemoglobin (MetHb) in erythrocytes was tested; only pNOBA and p‐hydroxylaminobenzoic acid (pHABA), a possible intermediate in the decomposition of pNOBA, proved to be reactive. Ultraviolet‐A exposure of rats, after intraperitoneal injection of CAP, led to 3.6 times the basic level of MetHb. In addition, covalent binding of 3H‐labeled CAP photoproducts to the skin of the back and to the ears was found, which was 9.1 and 3.2 times higher, respectively, than the dark values. Toxicity toward bone marrow cells of all photoproducts was established in vitro. p‐Nitrobenzaldehyde, pNOBA andpHABA were 20, 6 and 6 times more toxic than CAP, respectively. These results show that photodecomposition of CAP in vivo does occur. Its reactive photoproducts are able to cause damage that may lead to (systemic) side effects. The latter is supported by the fact that the nature of the reactive products, nitroso‐ and hydroxylamino derivatives, is the same as the expected metabolites.
DAMAGE TO URACIL‐ AND ADENINE‐CONTAINING BASES, NUCLEOSIDES, NUCLEOTIDES AND POLYNUCLEOTIDES: QUANTUM YIELDS ON IRRADIATION AT 193 AND 254 NM
Authors: Gurzadyan Gagik G. , Görner Helmut
Published: January 2008

AbstractPhotoreactions, such as base release and decomposition of the base moiety, induced by either 20 ns laser pulses at 193 nm or continuous 254 nm irradiation, were studied for a series of uracil and adenine derivatives in neutral aqueous solution. The quantum yield of chromophore loss (φ) depends significantly on the nature of the nucleic acid constituent and the saturating gas (Ar, N2O or O2). In the case of polynucleotides the destruction of nucleotides was measured by high‐performance liquid chromatography after hydrolysis; the quantum yields (φ) are comparable to those of chromophore loss or larger. The φcland aφdnof 0.04–0.1 for poly(U) and poly(dU), obtained for both wavelengths of irradiation, are due to processes originating from the lowest excited singlet state,i.e. formation of photohydrates and photodimers, and a second part from photoionization using λirr= 193 nm. Irradiation at 193 nm effectively splits pyrimidine dimers and thus reverts them into monomers. The quantum yield for release of undamaged bases (φbr) from nucleosides, nucleotides and polynucleotides upon irradiation at 254 nm is typically φbr= (0.1–1) × 10−4Breakage of theN‐glycosidic bond is significantly more efficient for λirr=193 nm,e.g. φbr= 1.1 × 10−3, 0.8 × 10−3, 4.3 × 10−3and 0.5 × 10−3for poly(A), poly(dA), poly(U) and poly(dU) in Ar‐saturated solution, respectively. Enhanced φ values for λirr= 193 nm, essentially for adenine and its derivatives, are caused by photo‐processes that are initiated by photoionization.
PHOTOOXIDATION OF 2‐MERCAPTOETHANOL BY VARIOUS WATER‐SOLUBLE PHTHALOCYANINES IN AQUEOUS ALKALINE SOLUTION UNDER IRRADIATION WITH VISIBLE LIGHT
Authors: Schneider Gerhard , Wohrle Dieter , Spiller Wolfgang , Stark Johannes , Schulz‐Ekloff Günter
Published: January 2008

Abstract A selection of charged water‐soluble phthalocyanines was employed for the photocatalytic oxidation of 2‐mercaptoethanol in aqueous alkaline solution in the presence of oppositely charged detergents. Most efficient are Zn(II) and Al(III) phthalocyaninetetrasulfonic acids, which oxidize the thiolate to the sulfonic acid and sulfate, whereas Co(II)phthalocyaninetetrasulfonic acid does not exhibit a photoeffect. During the photooxidation reactions, decomposition (photobleaching) of the zinc phthalocyanine derivatives occurs, whereas the analogous alumina chelates are more stable. Covalent binding of Zn(II)phthalocyanine derivatives to silica carriers results in photocatalytic activities even in the absence of detergents, since the immobilization of the complexes preserves the required monomeric state. Moreover, the photodecomposition (bleaching) of the heterogenized complexes is strongly retarded. For the photo‐oxidations mainly the pathway via the sensitized formation of singlet oxygen with subsequent oxidation reactions is valid. Hydrogen peroxide as one reduction product of oxygen was found.
PHOTOPHYSICAL STUDY OF THE SCHIFF BASES OF 5′‐DEOXYPYRIDOXAL AND n‐HEXYLAMINE IN CATIONIC MICELLES
Authors: Vazquez Segura Miguel A. , Donoso Josefa , Muntoz Francisco , Blanco Francisco Garciaa , Garciaa del Vado M. Angeles , Echevarriaa Gerardo
Published: January 2008

Abstract‐The absorption and fluorescence spectra of the Schiff bases formed between 5′‐deoxypyridoxal and n‐hex‐ylamine in aqueous media containing different concentrations of the cationic surfactant hexadecyltrimethylammonium bromide were recorded at 25°C. The quantum yields of fluorescence of the different zwitterionic and enol forms of the chemical species of the Schiff bases occumng in media of pH 4.5–8.5 were determined. Also, the fluorescence quenching resulting from the presence of the surfactant and that of iodide ion were analyzed. From the results obtained it follows that the zwitterionic forms do not interact with the cationic surfactant, whereas the enol forms do interact with it.
DOES LOW‐INTENSITY He‐Ne LASER RADIATION PRODUCE A PHOTOBIOLOGICAL GROWTH RESPONSE IN Escherichia coli?
Authors: Daniels L. L. , Quickenden T. I.
Published: January 2008

Abstract A photobiological study was camed out on the bacterium Escherichia coli in order to determine whether stimulation of growth occurred after irradiation of an inoculum with coherent red light. No enhancement or inhibition of growth was observed for cultures of the bacterium following irradiation of inocula with a Helium‐neon laser (continuous wave, λ= 632.8 nm) at irradiances of 7.7 × 1015 and 1.8 × 1016 photons cm−2 s−1 using fluences of 4.5 × 10−‐1 and 4.5 J cm−2 at each irradiance. Bacterial growth in irradiated and control cultures was monitored during a growth period of ca 2 h using a viable count technique after inocula in the early exponential phase had been diluted with fresh growth medium. These results do not provide support for the work of Kam et al. (1983, Nuov. Cim. 2D, 1138–1144), and Tiphlova and Karu (1988, Photochem. Photobiol. 48, 467–471), which appear to show substantial enhancement of E. coli growth under these conditions.
ASCORBIC ACID GLYCATION OF LENS PROTEINS PRODUCES UVA SENSITIZERS SIMILAR TO THOSE IN HUMAN LENS
Authors: Ortwerth B. J. , Linetsky Mikhail , Olesen Paul R.
Published: January 2008

Abstract—

‐Soluble calf lens proteins were extensively glycated during a 4 week incubation with ascorbic acid in the presence of oxygen. Amino acid analysis of the dialyzed proteins removed at weekly intervals showed an increasing loss of lysine, arginine and histidine, consistent with the extensive protein cross‐linking observed. Irradiation of the dialyzed samples with UVA light (1.0 kJ/cm2 total illumination through a 338 nm cutoff filter) caused an increasing loss of tryptophan, an additional loss of histidine and the production of micromolar concentrations of hydrogen peroxide. No alteration in amino acid content and no photolytic effects were seen in proteins incubated without ascorbic acid or in proteins incubated with glucose for 4 weeks. The rate of hydrogen peroxide formation was linear with each glycated sample with a maximum production of 25 nmol/mg protein illuminated. The possibility that the sensitizer activity was due to an ascorbate‐induced oxidation of tryptophan was eliminated by the presence of a heavy metal ion chelator during the incubation and by showing equivalent effects with ascorbate‐incubated ribonuclease A, which is devoid of tryptophan. The ascorbate‐incubated samples displayed increasing absorbance at wavelengths above 300 nm and increasing fluorescence (340/430) as glycation proceeded. The spectra of the 4 week glycated proteins were identical to those obtained with a solubilized water‐insoluble fraction from human lens, which is known to have UVA sensitizer activity.

The incubation of lens proteins with dehydroascorbic acid or l‐threose, but not fructose, produced equivalent glycation, protein crosslinking and sensitizer activity. The relative sensitizer activity of the 4 week glycated sample was quantitatively very similar to that of a water‐insoluble fraction from aged human lenses. These data are consistent with the hypothesis that the protein‐bound brunescence in the lens may be advanced glycation endproducts, which are formed in large part by the oxidation products of ascorbic acid, and that these compounds may contribute significantly to the UVA sensitizer activity present in aged human lenses.
NEAR‐INFRARED‐FT‐RAMAN STUDY OF AGGREGATION OF BACTERIOCHLOROPHYLL c IN WHOLE LIVING Chlorobium limicola
Authors: Sato Hidetoshi , Uehara Kaku , Ishii Takasada , Ozaki Yukihiro
Published: January 2008

Abstract—

Near‐infrared excited Fourier‐transform Raman spectra have been measured for whole living Chlorobium limicola f. thiosulfatophilum to explore in situ structure of bacteriochlorophyll c (BChl‐c). The spectra, whose Raman bands are preresonance enhanced via a Qy band of BChl‐c, did not contain contributions from the major components of bacteria such as proteins and lipids. Therefore, the spectra provide selective structural information about BChl‐c in the chlorosomes in a totally nondestructive manner. A marker band, appearing at 1605 cm‐1 for the coordination number of the Mg atom, shows that BChl‐c in the chlorosomes is five coordinate. The Raman spectrum of living bacteria closely resembles that of BChl‐c in water‐saturated carbon tetrachloride (w‐std CC14) where it is comprised of dimer, tetramer and polymer spectra. However, a band assigned to a C=O stretching mode of the 131‐keto group is identified only at 1641 cm‐1. A band arising from the free keto carbonyl group, which appears in the spectrum of BChl‐c in w‐std CC14, is not observed in the spectra of bacteria. These observations suggest that BChl‐c in the chlorosomes forms mostly coordinate polymeric species whose structure is very similar to that of BChl‐c in w‐std CC14.
CHEMILUMINESCENT DIPHENYLACETALDEHYDE OXIDATION BY MITOCHONDRIA IS PROMOTED BY CYTOCHROMES and LEADS TO OXIDATIVE INJURY OF THE ORGANELLE
Authors: Nantes Isbli L. , Cilento Giuseppe , Bechara Etelvino J. H. , Vercesi Aníbal E.
Published: January 2008

Abstract—

Plant and animal mitochondria promote the aerobic oxidation of diphenylacetaldehyde (DPAA). This process is accompanied by chemiluminescence and rotenone‐insensitive oxygen uptake. Tn rat liver and potato tubers, mitochondrial swelling is concurrently detected. Light emission and oxygen consumption decreased (about 50%) in cytochrome c‐depleted mitochondria. A model system–cytochrome c or b5/dihexadecylphosphate liposomes–was also able to oxidize DPAA with parallel reduction of the cytochrome. Reduction of respiratory complex I or I plus II by addition of rotenone or antimycin A, respectively, did not prevent DPAA oxidation. However, when all cytochrome was reduced by addition of cyanide, aldehyde oxidation was completely suppressed. Altogether these data indicate that respiratory cytochromes are responsible for DPAA oxidation with production of excited species and consequent mitochondrial permeabilization.
SUBCELLULAR DISTRIBUTION OF HYPERICIN IN HUMAN CANCER CELLS
Authors: Miskovsky Pavol , Sureau Franck , Chinsky Laurent , Turpin Pierre‐Yves
Published: January 2008

Abstract—

Confocal laser microspectrofluorometric measurements on human T47D mammary tumor cells have been performed to assess the intracellular distribution of hypericin within the various cell compartments: cytoplasmic membrane, cytoplasm and nucleus. Confocal fluorescence measurements obtained from microvolumes (˜ 1 μm3) located within the three sites of interest show that, while being primarily located in the cell membrane and cytoplasm after a short‐term incubation in a 10−6M hypericin‐containing culture medium, hypericin actually reaches the inside of the cell nucleus after a long‐term incubation (210 min). Moreover, owing to the relative fluorescence quantum yields of hypericin determined in vitro when the molecule interacts with DNA, membrane and protein model systems, it is assumed that there is a significant accumulation of the drug into the cell nucleus. Consequently, the nucleus has to be considered as a possible target for the toxic action of hypericin.
EPR PERSISTENCE MEASUREMENTS OF UV‐INDUCED MELANIN FREE RADICALS IN WHOLE SKIN
Authors: Collins Bernard , Poehler Theodore O. , Bryden Wayne A.
Published: January 2008

Abstract—

Electron paramagnetic resonance is used to detect the formation of free radicals caused by exposure to ultraviolet radiation in chemically untreated rabbit skin. A fast jump in EPR signal level, occurring over a few seconds, is observed immediately after a skin sample is exposed to UV. This is followed by a slower increase toward an elevated steady‐state signal over a period of hours as the skin is continuously exposed to a UV light source. Upon cessation of UV light exposure, EPR signal levels undergo an abrupt drop followed by a slower decay toward natural levels. Elevated free radical concentrations following UV exposure are found to persist for several hours in whole skin. These results are consistent with time‐resolved EPR measurements of photoinduced radicals in various natural melanins.
SEQUENCE SPECIFICITY OF TETRAHYDROBENZOPSORALEN PHOTOBINDING TO DNA
Authors: Mobilio S. , Tondelli L. , Capobianco M. , Gia O.
Published: January 2008

Abstract— The sequence specificity of photobinding to DNA of two tetrahydrobenzopsoralen derivatives has been investigated by testing the photoreactivity toward a number of self‐complementary oligonucleotides. The thermodynamic constant for noncovalent binding to each DNA sequence was evaluated. The extent of photoreactivity was greatly dependent upon base composition. The two tetracyclic compounds show similar behavior in comparison to other bifunctional derivatives. Their overall rate constants were greatly enhanced in comparison to classical psoralens. However, their high efficiency of covalent binding is counterbalanced by low affinity for noncovalent interaction with DNA.
EFFECT OF AGGREGATION ON THE HEMATOPORPHYRIN‐SENSITIZED PRODUCTION OF SINGLET MOLECULAR OXYGEN
Authors: TAnielian C. , HEINRICH G.
Published: January 2008

Abstract—The hematoporphyrin‐sensitized production of singlet molecular oxygen, O2(1Δg), has been investigated in methanol and in aqueous solution. The quantum yield for formation of O2(1Δg) (ΦΔ) has been measured by both steady‐state (oxygen consumption) and time‐resolved (near‐infrared luminescence) methods. In methanol, both techniques indicate that ΦΔ= 0.76 and the value remains independent of sensitizer concentration over a wide range. This finding is consistent with the dye persisting in a monomelic form in methanol solution. In contrast, ΦΔdecreases markedly with increasing sensitizer concentration in water due to dimerization of the dye. Analysis of the steady‐state data indicates ΦΔvalues of 0.74 and 0.12, respectively, for monomer and dimer. It is further shown that the efficiency whereby quenching of the triplet state by O2results in generation of O2(1Δg) is substantially lower for the dimer than for the corresponding monomer. Because monomer and dimer possess quite different absorption spectral profiles, the efficacy for photodynamic action with hematoporphyrin exhibits a pronounced wavelength dependence.
THE STRUCTURE OF PHYCOBILISOMES IN MUTANTS OF Synechococcus sp. STRAIN PCC 7942 DEVOID OF SPECIFIC LINKER POLYPEPTIDES
Authors: Bhalerao R. P. , Collier J. L. , Gustafsson P. , Grossman A. R.
Published: January 2008

Abstract— The effect of elimination of the 30, 33 and 9 kDa phycobilisome rod‐linker polypeptides on rod length was examined by electron microscopy of phycobilisomes isolated from wild‐type Synechococcus sp. strain PCC 7942 and from genetically engineered mutants with lesions in the genes encoding the rod‐linker polypeptides. The maximum rod length in the absence of the 33 kDa linker polypeptide was two phycocyanin hexamers, whereas rods with up to five hexamers were found in the mutant strain lacking the 30 kDa linker polypeptide. Elimination of the 9 kDa linker polypeptide did not have a significant effect on rod length. Finally, mutants lacking either the 30 or 33 kDa rod‐associated linker polypeptides had an increased number of rods that terminated with a phycocyanin trimer. These observations are discussed with respect to the role of the linker polypeptides in the biosynthesis of the rod substructure.
PHOTOINDUCED TRANSIENT PHENOMENA IN CYCLODEXTRIN SOLID COMPLEXES: PHOTOCHEMISTRY OF AROMATIC KETONES
Authors: Barra Mónica , Scaiano J. C.
Published: January 2008

Abstract—

The photochemistry of benzophenone (BP) in cyclodextrin (α‐, ß‐ and γ‐CD) solid complexes has been examined by time‐resolved diffuse reflectance laser‐flash photolysis techniques. Benzophenone is photoreduced as a consequence of hydrogen abstraction from the CD cavity. Both BP phosphorescence and diphenylketyl radical fluorescence spectra in CD solid complexes were recorded at room temperature. Lifetime distribution analysis is used in order to describe the dynamics of triplet decay. The most probable BP triplet lifetime is found to decrease as the size of the CD cavity decreases (α‐CD = 0.3 (µs, ß‐CD = 0.5 µs and γ‐CD = 1.2 (µs). This observation contrasts with that for xanthone, a more rigid, yet structurally related ketone (α‐CD = 8 µs, ß‐CD = 3 µ.s and γ‐CD = 0.6 (µs) studied previously. The differences are interpreted in terms of changes in triplet reactivity and of restrictions on molecular mobility.
THE GENERATION OF HYDROGEN PEROXIDE BY THE UVA IRRADIATION OF HUMAN LENS PROTEINS
Authors: Linetsky Mikhail , Ortwerth B. J.
Published: January 2008

Abstract—

The water‐insoluble proteins from aged human lens are known to contain protein‐bound chromophores that act as UVA sensitizers. The irradiation of a sonication‐solubilized, water‐insoluble fraction from human lenses (55–75 years) with UVA light (1.5 kj/cm2, λ > 338 nm) caused an oxygen‐dependent photolysis of tryptophan, not seen when either α‐crystallin or lysozyme were irradiated. The suggested requirement for active oxygen species was consistent with a linear increase in hydrogen peroxide formation, which was also observed. A final concentration of 55 µM H2O2 was attained, with no H202 being detected in either dark‐incubated controls or in irradiated samples of native proteins. The UVA‐dependent H2O2 formation was increased 50% by superoxide dismutase (SOD) and abolished by catalase, arguing for the initial generation of superoxide anion. A linear photolysis of histidine and tryptophan was also seen; however, the addition of SOD or SOD and catalase had no effect on the photolytic destruction of either amino acid. Superoxide dismutase increased the oxidation of protein SH groups implicating H2O2, but SOD and catalase caused a decrease in SH oxidation only at later time periods. The direct addition of H2O2 to a water‐insoluble sonicate supernatant fraction caused only a slight oxidation of SH groups, but this was increased four‐ to eight‐fold when the protein was denatured in 4.0 M guanidine hydrochloride.

Overall, the data suggest a UVA‐dependent oxidation of protein SH groups via H2O2 generated within the large protein aggregates of the water‐insoluble fraction. These data also provide a mechanism for oxidation of the sulfur‐containing amino acids in vivo—a process that is known to accompany the formation of age‐onset cataracts.
SPECTRAL DEPENDENCE OF UV‐INDUCED IMMEDIATE AND DELAYED APOPTOSIS: THE ROLE OF MEMBRANE AND DNA DAMAGE
Authors: Godar Dianne E. , Lucas Anne D.
Published: January 2008

Abstract— The phototoxicity of each waveband region of UV radiation (UVR), i.e., UVA (32CM100 nm), UVB (290–320 nm) and UVC (200–290 nm), was correlated with an apoptotic mechanism using equilethal doses (10% survival) on murine lymphoma L5178Y‐R cells. Apoptosis was qualitatively monitored for DNA “ladder” formation (multiples of 200 base pair units) using agarose gel electrophoresis, while the percentages of apoptotic and membrane‐permeabilized cells were quantified over a postexposure time course using flow cytometry. The UVA1 radiation (340–400 nm) induced both an immediate (<4 h) and a delayed (>20 h) apoptotic mechanism, while UVB or UVC radiation induced only the delayed mechanism. The role of membrane damage was examined using a lipophilic free‐radical scavenger, vitamin E. Immediate apoptosis and membrane permeability increased in a UVA1 dose‐dependent manner, both of which were reduced by vitamin E. However, vitamin E had little effect on UVR‐induced delayed apoptosis. In contrast, the DNA damaging agents 2,4‐ and 2,6‐diaminotoluene exclusively induced delayed apoptosis. Thus, immediate apoptosis can be initiated by UVA 1‐induced membrane damage, while delayed apoptosis can be initiated by DNA damage. Moreover, the results suggest that immediate and delayed apoptosis are two independent mechanisms that exist beyond the realm of photobiology.