bluuebunny/crossref_metadata_2025 huggingface dataset:
IMPROVING THE EFFICIENCY OF HEMATOPORPHYRIN PHOTOTHERAPY OF OCULAR TUMORS
Authors: Lutty GerardA. , Fortune Myrmuth , Hochheimer BernardF.
Published: January 2008

Malignant melanoma of the choroid is the most common primary intraocular tumor in adult humans. Controversy exists over which is the most effective therapy. One therapeutic modality that has not been thoroughly investigated is hematoporphyrin derivative phototherapy (HPdPRT), a technique used successfully in the clinic on many non‐ocular tumors.

The effect of HPd PRT on an ocular, amelanotic melanoma was evaluated using Greene melanoma implanted on pigmented rabbit iris. The parameters used clinically on non‐ocular tumors (intravenous 2.5 mg HPd kg‐1 body weight and irradiation at 633 nm 48 h later) were totally ineffective in killing Greene melanoma implanted on the iris. The dose of dye (2.5–5 mg kg‐1), wavelength of light (500‐700 nm), and illumination intensity were varied to determine the most efficient parameters for treating this tumor. The most important parameter was dye dose; increasing it to 5 mg kg‐1 resulted in some control of tumor growth. Administering 100% O2 prior to and during irradiation also improved HPd PRT cytotoxicity. The use of pulsed light (pulses of 1 or 2 min) further enhanced killing and reduced the length of irradiation needed. These studies suggested that HPd PRT might be used efficiently on ocular melanomas.
A FILTER BINDING ASSAY FOR CHARACTERIZATION OF ANTIBODIES TOWARDS DAMAGED DNA
Authors: Helland Dag E. , Eggset Guri , Krokan Hans
Published: January 2008

A nitrocellulose filter binding assay was used to characterize rabbit antibodies specific for UV‐irradiated DNA. The dissociation constant for the UV‐DNA‐antibody complex was found to be 4.2 × 10−12 M. No significant binding to unirradiated DNA was observed. Unlabelled single‐stranded and double‐stranded DNA competed with equal efficiency for the radioactively labelled antigen (UV‐irradiated φX174 DNA). The antibodies also bound to OsO4‐treated DNA, suggesting that these polyclonal antibodies also recognize minor photoproducts. Caffeine efficiently decreased binding of the antibodies to UV‐irradiated DNA.
RESTRICTION ENZYME CLEAVAGE OF UV‐IRRADIATED DNA: A COMPARISON OF FAR‐UV AND MID‐UV WAVELENGTHS
Authors: Moore S. P. , Mcaleer M. A. , Moss S. H.
Published: January 2008

UV‐irradiated DNA is less susceptible to restriction by Type II endonucleases than unirradiated DNA presumably due to photolesions formed in the recognition sites. Previous reported studies have used 254 nm radiation or 313 nm plus acetophenone, both treatments which introduce pyrimidine dimers in preference to other photolesions. To assess the effect of a longer wavelength, at which the ratio of pyrimidine dimer formation to the formation of other photolesions is reduced, two different DNAs were irradiated with UV of either 254 or 313 nm and restricted with suitable restriction endonucleases. Restriction patterns were analysed for novel fragments resulting from UV‐induced alteration of enzyme recognition sites. EcoRI restriction of 254 nm irradiated lambda DNA produced six novel bands, only three of which were observed following restriction of 313 nm irradiated lambda. These three represented the largest fragments resulting from single site blocks. Novel fragments involving adjacent site blocks observed at 254 nm were not found with 313 nm radiation. Comparison of 254 nm irradiated pSV2gpt to that irradiated at 313 nm, both restricted with Dral, revealed a more complex pattern. Although all sites were singly blocked by radiation of both wavelengths, multiple site blocks produced by 313 nm radiation did not occur in the order predicted by the 254 nm radiation dose response. These data suggest that certain sites in pSV2gpt may be more refractory to multiple site blocks than others when irradiated at 313 nm.
RNA PROTEIN CROSSLINKS INTRODUCED INTO E. coli RIBOSOMES BY USE OF THE INTRINSIC PROBE 4‐THIOURIDINE
Authors: Hajnsdorf Eliane , Dubreuil Yolande Lemaigre , Bezerra Roberto , Favre Alain , Expert‐BezanÇon Alain
Published: January 2008

Abstract— 70S Ribosome substituted by the uridine photoactivable analogue 4‐thiouridine has been prepared by an in vivo method (substitution level 4.5%). The r‐proteins crosslinked to 16S and 23S rRNA before and after 366‐nm photoactivation were identified. Proteins S2‐S7‐S9/11‐S18 are found linked to 16S RNA in dark‐prepared 30S subunits. Illumination increases uniformly their binding by a factor of 2.5. Similarly, proteins L5‐L15‐L18‐L23‐L28‐L32 are found crosslinked to 23S RNA in dark‐prepared 50S subunits. Photoactivation increases their binding but in addition promotes the covalent linking of proteins L1‐L3‐L4.
NECROSIS OF MURINE TAIL SKIN FOLLOWING PHOTODYNAMIC TREATMENT WITH meso‐tetra‐(p‐SULPHOPHENYL) PORPHINE (TPPS)
Authors: Moore James V.
Published: January 2008

Abstract. Albino mice were injected intravenously with 2 mg of meso‐tefra‐(p‐sulphophenyl) porphine (TPPS) and subsequently their tails were exposed to a range of doses of full‐spectrum visible light. At a power density of 75 mW cm‐2, a 50% incidence of gross necrosis of the tail skin (ED50) occurred at a light dose of 130 J cm‐2. For haematoporphyrin derivative at the same administered dose, the ED50 was 33 J cm‐2. Increasing the interval between TPPS and light from 1 to 34 days did not spare the tail skin, in terms of an increase in ED50. The slopes of curves of incidence of tail necrosis vs light dose were steep: 1/slope ranged between 20 and 50 J cm‐2.
BLUE LIGHT INDUCED, REVERSIBLE IN ACTIVATION OF THE TONOPLAST‐TYPE H+‐ATPase FROM CORN COLEOPTILES IN THE PRESENCE OF FLAVINS
Authors: Krauss Wolf , Schiebel Gabriele , Eberl Dagmar , Hager Achim
Published: January 2008

Abstract— Irradiation (λmax 447 nm; 58.5 W m‐2) of a microsomal membrane fraction of corn coleoptiles for 5 min in the presence of the in vivo concentration of riboflavin inactivates the tonoplast‐type H+‐ATPase. This inhibition is O2‐dependent, is enhanced in D2O and suppressed by NaN3, indicating participation of singlet molecular oxygen in the inactivating mechanism. Besides singlet oxygen, the superoxide anion (O2‐) is generated during irradiation, which obviously has no effect on the H+‐pumping activity. However, in the presence of superoxide dismutase (SOD), O2‐ is transformed into H2O2 which causes an additional strong inhibition of H+. ATPase activity. This inhibition can be increased by ethylenediaminetetraacetic acid (EDTA), which is known to be an electron donor of the excited flavin molecule. In contrast, catalase prevents the H2O2‐mediated photoinactivation of the H+ ‐ATPase. The light dependent inactivation of H+‐transport does not occur if reduced glutathion (GSH) is added prior to or after irradiation. These results indicate that the blue light mediated inhibition of the H+‐ATPase is mediated by singlet oxygen and H2O2 which oxidize essential SH‐groups of the enzyme into disulfides. Reduction of the formed disulfides by GSH restores the activity of the enzyme.
PICOSECOND ABSORPTION SPECTROSCOPY OF CHLOROPHYLL A DIHYDRATE
Authors: Malý P. , Danielius R. , Gadonas R.
Published: January 2008

Abstract— The solution of chlorophyll a in hexane with more than 70% of chlorophyll molecules in the form of the dihydrate (CHl‐a.2H2O)n is investigated at room temperature by picosecond absorption technique. The transient difference spectra and the kinetic dependences of the absorption changes are measured for several excitation and probe wavelengths. Creation of a new state with blue‐shifted absorption band is observed in the system after excitation. A model of the behaviour of the system after excitation is proposed and checked by comparison of the computer‐simulated spectral and time dependences with the experimental data. According to the model, about 30% of excited molecules are in the state with the 0.046 eV shift of the absorption band in comparison with the ground state absorption. The lifetime of this state has 170‐ps component. The rest of the excited molecules are in the first excited state with the decay time component of 37 ps.
LASER FLASH PHOTOKINETIC STUDIES OF ROSE BENGAL SENSITIZED PHOTODYNAMIC INTERACTIONS OF NUCLEOTIDES AND DNA
Authors: Lee Plato C. C. , Rodgers Michael A. J.
Published: January 2008

Abstract— Laser flash photolysis studies of the production of the triplet state of the xanthene dye, rose bengal (RB), have been carried out. The reactions of this state with oxygen to form singlet oxygen and the superoxide anion radical have been observed and yields measured. Quenching of RB(T1) by oxygen leads to approximately 75% singlet oxygen and 20% superoxide. The reactivity of these species‐RB(T1), O2(1Δg) and O2‐—with four nucleotides and DNA have been determined. Only guanine residues showed any noticeable reaction at neutral pH. At higher pH guanine rate constants increased. The consequences to biological photodynamic processes are discussed.
PHOTOSENSITIZING EFFECTS OF HEMATOPORPHYRIN DERIVATIVE IMMOBILIZED ON SEPHAROSE
Authors: Gibson Scott L. , Murant Richard S. , Hilf Russell
Published: January 2008

Abstract— The cytotoxicity that ensues following photosensitization by hematoporphyrin derivative (Hpd) is attributed to production of singlet oxygen. Many of the cellular end points reported to be affected are localized to membranes, hydrophobic environments conducive to partitioning of hydrophobic porphyrins in Hpd. In order to test the hypothesis that efficacy of Hpd‐induced photosensitization is enhanced by its ability to freely enter cells or subcellular organelles, we immobilized Hpd on a sepharose support. This immobilized reagent was found to produce 1O2 when photoradiated, in yields similar to those observed for Hpd in solution, as evidenced by the bleaching of p‐nitrosodimethylaniline in the presence of imidazole. The immobilized Hpd was capable of photosensitizing, i.e. inhibit, cytochrome c oxidase activity in intact mitochondrial membranes and in aqueous solution. However, enzymes located on the interior of mitochondrial membranes (F0F1 ATP synthase and succinate dehydrogenase), in the mitochondrial matrix (malate dehydrogenase), or on the inside of the plasma membrane, (Na++ K+)‐ ATPase, were unaffected by immobilized Hpd plus photoradiation compared to free Hpd. The results suggest that photosensitization by Hpd most likely arises from entry of the photosensitizer into the biological membrane, although proteins on the exterior membrane surface may be susceptible to damage by 1O2 produced in proximity to their location.
CALCIUM CONTROL OF PHOTOTACTIC ORIENTATION IN Chlamydomonas reinhardtii: SIGN AND STRENGTH OF RESPONSE
Authors: Morel‐Laurens N.
Published: January 2008

Abstract— Chlamydomonas reinhardtii responds to a blue light stimulus by an oriented swimming (phototaxis) toward or away from the stimulus source. In this study it is established that the sign and strength of the phototactic response are a complex function of extracellular [Ca2+], stimulus fluence rate, time of analysis after onset of stimulation and light pretreatment. At very low extracellular [Ca2+] the response is weak and usually negative. At [Ca2+] close to the preconditioning level, phototactic response becomes stronger and positive. As [Ca2+] is raised further, the initial (2 s) response remains positive but the long term (20 s) becomes negative and very strong. At extremely high [Ca2+] the cells become immobile. This bimodal behavior suggests that two different mechanisms determine the direction of the turn. Data cannot be explained in terms of a simple model. The model which accounts for most of the details of the behavior is that of Kamiya and Witman (1984), which proposes that positive response is triggered by a transient increase in intracellular [Ca2+] and negative response by a decrease below unstimulated level of Ca2+, at least in the range of 10‐9‐10‐6M [Ca2+]. The strong negative orientation which follows an initial positive response above this level of [Ca2+], in these experiments, is best explained by an adaptation of the cells due to an increased (on average) intracellular [Ca2+].
THE PHOTOCHEMISTRY OF SPECIFIC TRYPTOPHAN RESIDUES IN PROTEINS AS ANALYZED BY THE FLUORESCENT SCANNING OF TRYPTIC PEPTIDE MAPS
Authors: Dillon James , Chiesa Raúl , Spector Abraham
Published: January 2008

Abstract— The fact that most proteins contain several tryptophans hinders the investigation of the photochemistry of a particular indole residue. A method is presented here that can be used to investigate the photochemistry of specific tryptophan residues in proteins. It consists simply of separating the peptides of a proteolytically digested protein by TLC and then scanning the peptides at the fluorescent maximum of tryptophan. The assignment of the resultant peaks to a particular peptide is based on the chromatographic comparison of the scans with peptide maps.

Using this method, the photochemistry of the tryptophan residues in alpha crystallin, a major protein of lenses, was investigated. Under photolytic conditions that mimic the transmission characteristics of the cornea (>293 nm), it was found that there is a differential photolysis of the tryptophan residues in the protein; with Trp‐9 in the N‐terminal peptide photolyzing at a considerably faster rate than Trp‐60. In addition to tryptophan, photolytic losses of tyrosine were assessed by scanning the peptide maps at the tyrosine fluorescent maximum. Only one tyrosine residue photolyzes under these conditions. The differential photolysis of the tryptophan residues is explained in part by the presence of residues in the vicinity of the indole moieties.
OXIDATION OF RIBOSE MOIETY OF ADENOSINE INDUCED BY IRRADIATION OF NEAR‐UV LIGHT IN THE PRESENCE OF IRON(III) CHLORIDE
Authors: Araki Koji , Shiraishi Shinsaku
Published: January 2008

Abstract— Irradiation of near‐UV light in the presence of FeCl3 caused oxidation of adenosine with concomitant reduction of Fe(III) under either aerobic or anaerobic atmosphere. Major photoproducts were adenine and adenosine‐5′‐aldehyde, showing that oxidation took place mostly at the ribose moiety of adenosine. Detailed study showed that the reaction proceeded by the light absorption due to Fe(III) at 300‐350 nm.
TRANSIENT PHENOMENA IN THE PULSE RADIOLYSIS OF RETINYL POLYENES—7. RADICAL ANIONS OF VITAMIN A AND ITS DERIVATIVES
Authors: Bhattacharyya K. , Bobrowski K. , Rajadurai S. , Das P. K.
Published: January 2008

Abstract— Upon e‐‐pulse irradiation in nonprotic solvents, all‐trans retinol (ROH) and retinylmethyl ether (ROMe) form transient species (τ= 0.5–7μs, λmax=575–590 nm) identifiable as radical anions. Similar species are also formed upon laser pulse photoexcitation of these retinyl derivatives in the presence of N,N‐dimethylaniline in acetonitrile. In contrast, electron transfer or attachment to all‐trans retinyl acetate (ROAc) and palmitate (ROPa) results in ‘instantaneous’ loss of carboxylate anions from electron adducts giving the retinylmethyl radical (R‐, λmax= 395 nm, τk > 100 μ,s); the radical anions in these cases are too short‐lived to be detected by nanosecond pulse radiolysis. The lifetimes of radical anions of ROH and ROMe are very sensitive to water and alcohols (e.g. kq= 107M‐1 s‐1 with methanol as quencher for ROH‐ in tetrahydrofuran). Based on these findings, the spectral dissimilarity of the one‐electron reduction products from ROH and ROAc in alcohols and aqueous micelles becomes explainable in terms of fast formation of protonated radical anions (RH(OH), τ1/2, > 100 μs, λmax=370–375 nm) in the case of ROH and of retinylmethyl radical via loss of AcO‐ from radical anion in the case of ROAc. In tetrahydrofuran, the complexation of ROH‐ with cations such as Na+ and Bu4N+ affects the relative importance of its major decay modes, namely, protonation and dehydroxylation, the latter process being significantly enhanced by the presence of Na+.
CHANGES IN CHLOROPHYLL‐PROTEIN COMPLEXES ASSOCIATED WITH JUNE YELLOWS OF STRAWBERRY*
Authors: Jeong B‐R. , Daley L. S. , Postman J. , Proebsting W. M. , Lawrence F. J.
Published: January 2008

Abstract— June yellows (J‐y) of strawberry (Fragaria) is an inheritable condition for which no causal pathogen has been demonstrated. Spectroscopic analysis of intact leaf lamina was applied to strawberry leaves with J‐y. The spectra were analyzed by fourth derivative technique. Differences were found between asymptomatic and affected leaves with respect to chlorophyll‐protein complexes. Affected leaves show spectra consistent with loss of certain chlorophyll‐a‐proteins (Ca). Distinct types of effects are found. In one type Ca 684 decreases, in another Ca 693 is diminished. Studies of strawberry clone pedigree suggest that Ca 684 losses are observed in clones with Howard 17 parentage, and Ca 693 losses in clones with Aberdeen parentage. One clone with both Howard 17 and Aberdeen parentage had a spectra consistent with diminished Ca 684 and Ca 693. The simplest explanation of the data is that J‐y results from several different types of genetic lesions on different Ca. Some viral infection effects on Ca spectra are also described.
POLYETHYLENE GLYCOL‐MODIFIED HEMATOPORPHYRIN AS PHOTOSENSITIZER
Authors: Kodera Yoh , Ajima Ayako , Takahashi Katsunobu , Matsushima Ayako , Saito Yuji , Inada Yuji
Published: January 2008

Abstract— Hematoporphyrin, having two carboxylic groups, was coupled with α‐(3‐aminopropyl)‐ω‐methoxypoly(oxyethylene), PEG‐NH2, through acid‐amide bond formed with carbodtimide. PEG‐modified hematoporphyrin was readily soluble not only in neutral aqueous solution but also in organic solvents. Its absorption spectrum showed a sharp band at 376 nm in neutral aqueous solution and at 403 nm in benzene. Modified hematoporphyrin acted as a photosensitizer; imidazole and indole were photooxidized in organic solvents such as benzene or chloroform, and uric acid was also photooxidized in neutral aqueous solution.
PHOTOSENSITIZATION OF NEOPLASTIC CELLS BY ANTHRAPYRAZOLES*
Authors: Kessel David
Published: January 2008

Abstract— Three anthrapyrazoles were tested for their ability to photosensitize murine leukemia cells in culture. Photosensitization was correlated with singlet oxygen yield. A cell line which exhibits anthrapyrazole resistance was also photosensitized, but the resulting photodamage was substantially less than in the drug‐sensitive cell line. This result has implications with regard to repair mechanisms in drug sensitive vs resistant cells.
124‐kDa PHYTOCHROME IN MODEL MEMBRANE SYSTEMS: ASSOCIATION STUDIES AND COVALENT BINDING TO PREFORMED LIPOSOMES
Authors: Krieg Marianne , Braslavsky Silvia E. , Schaffner Kurt
Published: January 2008

Abstract— 124‐kDa Phytochrome from oat has been covalently bound to the surface of preformed unilamellar liposomes doped with functionalized lipids. The extent of phytochrome binding varied from 100% (to soybean lecithin and dioleoyl phosphatidylcholine liposomes) to (90 ± 10)% (to dimyristoyl phosphatidylcholine liposomes) and (50 ± 10)% to dipalmitoyl phosphatidylcholine liposomes). The photochromic properties of phytochrome were fully retained in the liposome‐bound systems. Attempts to bring about spontaneous incorporation and binding of the phytochrome to neutral and positively charged liposomes failed. These results were independent of liposome size, the presence of cholesterol, and whether phytochrome was added prior to or after the liposome formation.
RAPID TRANSMISSION OF A PHYTOCHROME SIGNAL FROM HYPOCOTYL HOOK TO COTYLEDONS IN MUSTARD (Sinapis alba L.)
Authors: OELZE‐KAROW HEIDEMARIE , MOHR Hans
Published: January 2008

Abstract— In mustard (Sinapis alba L.) cotyledons appearance of ‘potential capacity’ to phosphorylate is controlled by phytochrome (Pfr) through a threshold, all‐or‐none reaction. Phytochrome operates only if the hypocotyl hook is connected to the cotyledons for at least 2.5 min after the end of a 1 min inductive light pulse. Partial irradiations of hook and cotyledons show that in the case of induction of ‘potential capacity’ rapid transmission of the Pfr signal occurs from the hypocotyl hook to the cotyledons. Phytochrome within the cotyledons is totally ineffective in this regard. A 3 min red light pulse suffices for full transmission of the signal. It seems that an explanation of the facts we have observed requires a revision of the present views about communication between the organs of a plant.
ENERGETICS OF DNA REPAIR: EFFECTS OF TEMPERATURE ON DNA REPAIR IN UV‐IRRADIATED PERIPHERAL BLOOD LEUCOCYTES FROM CHRONIC MYELOID LEUKEMIC PATIENTS*
Authors: Sharma A. , Sharma R. , Jain V. K.
Published: January 2008

Abstract— The effects of different temperatures(34–43°C) were studied on the repair of UV‐induced (254‐nm) DNA damage and its energetics in peripheral blood leucocytes of chronic myeloid leukaemic patients. DNA repair was measured by the unscheduled DNA synthesis (UDS) technique. Cellular energy supply was modulated by inhibitors of oxidative phosphorylation (antimycin‐A) and glycolysis (2‐deoxy‐D‐glucose). It was observed that there is an increase in the amount of DNA repair with increasing temperatures up to 40°C and a fall thereafter. Longer periods of heat treatment (4 h) beyond 40°C were observed to further decrease the DNA repair. Increasing temperatures were observed to have no significant effect on the parameters of energy metabolism. Further, the activation energy of DNA repair was calculated as 92 ± 46 kJ/mol (22 ± 11 kcal/mol), which did not alter significantly even in the presence of inhibitors of energy metabolism.
DIRECT DETECTION OF SINGLET OXYGEN SENSITIZED BY NALIDIXIC ACID: THE EFFECT OF pH AND MELANIN*
Authors: Dayhaw‐Barker Pierrette , Truscott T. George
Published: January 2008

Abstract— Singlet oxygen yields are reported for the antibiotic nalidixic acid in D2O at pH values above and below its pK., in water. The φΔincreases on lowering the pH. The effect of eumelanin on the φΔ values is shown to be substantial at pH 4.4, but virtually zero above the pKn value. Human serum albumin seems to have little effect on the singlet oxygen yield at high pH in the presence of melanin. The results are correlated with the experimental and clinical observations relating to the photosensitizing activity of the drug.
BINDING, EXCITATION ENERGY TRANSFER AND PHOTOSENSITIZATION IN GRISEOFULVIN‐DNA MIXTURES
Authors: Neely W. C. , Siraj M. Y.
Published: January 2008

Abstract— The weak and reversible binding of the antifungal drug, griseofulvin (GF), to calf thymus DNA has been demonstrated by difference spectroscopy and the quenching of the fluorescence of GF by DNA observed. The value of Kn was determined to be 800 M‐1by fluorescence quenching titration. Adenosine and guanosine also exhibit difference spectra with GF and quench GF fluorescence indicating that they may be the site of both binding and energy transfer. The in vitro photosensitization of DNA by griseofulvin is shown to occur. It is proposed that the clinically observed in vivo photosensitizing action of griseofulvin may result from binding followed by excitation energy transfer and that this may also be important in the antifungal activity of the drug.
PHOTOBINDING OF CHLORPROMAZINE AND ITS SULFOXIDE IN VITRO AND IN VIVO
Authors: Schoonderwoerd S. A. , van Henegouwen G. M. J. Beijersbergen , Luijendijk J. J.
Published: January 2008

Abstract— Photosensitivity as observed after chlorpromazine (CPZ) treatment is enhanced in the UVA‐ rather than the UVB region, whereas CPZ has its absorption maximum at 305 nm. This long wavelength sensitivity has sometimes been ascribed to CPZ‐sulfoxide (CPZSO) which has an absorption maximum at 340 nm. We compared the photobinding properties of CPZSO and CPZ under both in vitro and in vivo conditions.

With 310 and 370 nm lamps CPZSO absorbs twice as much light as CPZ but still binds less efficiently to HSA in vitro. At wavelengths longer than 380 nm CPZSO does not absorb nor photobind to HSA (420 nm lamps) in contrast to CPZ.

In vivo the bioavailability of CPZ and CPZSO in ears, eyes and skin of the back of Wistar rats is comparable, yet irradiation with 370 nm light caused more CPZ‐photobinding in these tissues. Chlorpromazine binds relatively more compared to CPZSO, to constituents of deeper lying tissues (dermis). This corresponds with the observation that both the ratio of in vitro CPZ photobinding to CPZSO photobinding, and the penetrating ability of light in the skin increase with wavelength.

In the eyes, where the lens efficiently filters out light with wavelengths shorter than 370 nm, no CPZSO photobinding was observed, in contrast to CPZ; this also corresponds with the in vitro experiments. Therefore it seems more likely that the observed wavelength maximum in the photosensitivity action spectrum after CPZ treatment should be attributed to the non‐sulfoxidated drug rather than to the sulfoxidated compound.
TRIPLET ENERGIES AND ELECTRON AFFINITIES OF METHYL‐ACRYLATE AND METHYL‐METHACRYLATE
Authors: Schafer Olivier , Allan Michael , Haselbach Edwin , Davidson R. S.
Published: January 2008

Abstract— The gas phase electron affinities and triplet and singlet excitation energies of the title compounds have been measured by electron transmission and electron‐energy‐loss spectroscopies. The implications of the results to understanding the mechanism of electron‐beam curing of materials containing the acrylate and methacrylate moieties are discussed.
PHOTO‐CIDNP EVIDENCE FOR CHARGE‐TRANSFER INTERACTION BETWEEN SYNTHETIC WATER‐SOLUBLE PORPHYRINS AND GUANINE*
Authors: NouËN D. LE , MARKO J. , VERMEERSCH G. , FEBVAY‐GAROT N. , LABLACHE‐COMBIER A. , PERREE‐FAUVET M. , GAUDEMER A.
Published: January 2008

Abstract Photoreactions of aqueous solutions of synthetic water‐soluble porphyrins were studied by the 1H and 13C CIDNP technique. Strong polarizations, which were very sensitive to the presence of added acid, were observed on the cationic porphyrins (TMePyPH2‐TAPPH2) when irradiated through continuous UV‐visible light. They resulted from the reverse electron transfer between the semi‐oxidized and the semi‐reduced species of the derivative.

When the experiments were carried out in the presence of nucleobases, guanine (and its derivatives) was the only residue that was polarized. This is thoroughly interpreted in terms of a reversible electron transfer reaction leading to guanine photooxidation by the porphyrin excited triplet state. It was shown to be drastically pH‐dependent and was correlated to the redox potential of the porphyrin. It was not affected by the incident wavelength. The reaction proceeded through the intermediate formation of the correlated radical‐ion pair: porphyrin radical anion‐guanine radical cation. This study suggested that a Type I (free radical) reaction could be one of the primary processes in DNA photosensitization by porphyrins.
SELECTIVE DEGRADATION OF AMINO ACIDS PHOTOSENSITIZED BY TRYPTOPHAN IN POLYPEPTIDE STRUCTURES
Authors: Pigault Claire , Gerard Dominique
Published: January 2008

Abstract—

Polypeptides containing a basic amino acid close to their single tryptophan residue were irradiated with monochromatic 302 nm radiation. Tryptophan photolysis was monitored by absorption and fluorescence spectroscopy. Amino acid loss was evaluated by amino acid analysis. Only the protonated residues adjacent to tryptophan in the sequence were destroyed upon tryptophan excitation. This reaction is probably due essentially to direct interaction between the excited tryptophan and the neighbouring residue without electron solvation.
PHOTO‐INDUCED ELECTRON EJECTION FROM THE REDUCED COPPER OF Pseudomonas aeruginosa AZURIN
Authors: Corin Alan F. , Gould Ian R.
Published: January 2008

Abstract—

The reduced form of Pseudomonas aeruginosa azurin exhibits an enhanced absorbance in the UV compared to that of the oxidized protein. This enhancement has also been observed for azurins from other bacterial species and for another type I copper protein, plastocyanin. Pulsed laser excitation of the reduced azurin in the region of enhanced absorbance at 308 nm results in single photon, rapid (<30 ns) oxidation of the copper center and formation of the hydrated electron with a quantum yield of 0.05. The hydrated electron reacts in the expected manner with scavengers such as nitrous oxide, oxygen, acetone and nitromethane. In the absence of scavengers, the electron reacts with the protein, including the disulfide bond, to form the disulfide radical anion, observed at 410 nm. The overall photophysical event involves a charge‐transfer to solvent transition although the existence of intermediate states can not be excluded.
SINGLET OXYGEN INDUCED MUTAGENESIS OF BENZO[α]PYRENE DERIVATIVES
Authors: Seed John L. , Specht Kathleen G. , Dahl Thomas A. , Midden W. Robert
Published: January 2008

Abstract— Singlet oxygen activates the mutagenicity of several benzo[α]pyrene (BP) derivatives in the absence of mammalian metabolic action. This has been demonstrated using a separated‐surface‐sensitizer system for generating chemically pure singlet oxygen, eliminating most of the complications that arise with singlet oxygen generation by conventional photosensitization. Salmonella typhimurium bacteria were exposed to singlet oxygen in the presence of certain BP derivatives and the mutation frequency determined with an azaguanine forward mutation assay. The mutation frequency was increased by exposure to singlet oxygen compared to light‐only controls for those BP derivatives that were saturated at either the 7,8 or 9,10 positions but not both. The increase in mutuation frequency depends on both the concentration of BP derivative and on the dose of singlet oxygen. Mutation frequency was also significantly increased when bacteria were treated with a solution of trans‐7,8‐dihydrodiol‐BP that had been separately exposed to singlet oxygen, unequivocally demonstrating that the mutagenicity is due to the formation of a product of BP derivative oxidation by singlet oxygen and that this product has a lifetime at least on the order of minutes in acetonitrile. The requirement for singlet oxygen rather than some other form of reactive oxygen was confirmed by determination of the gas phase lifetime of the intermediate responsible for activating mutagenicity. This was performed by measuring the dependence of the mutation frequency on the distance separating the sensitizer from the target. This gives a value of 88 ± 35 ms, which is in excellent agreement with the mean value of 89 ms calculated from previous independent determinations of the gas phase lifetime of singlet oxygen reported in the literature.
EXPRESSION OF AN Anacystis nidulans PHOTOLYASE GENE IN Escherichia coli; FUNCTIONAL COMPLEMENTATION AND MODIFIED ACTION SPECTRUM OF PHOTOREACTIVATION
Authors: Takao Masashi , Oikawa Atsushi , Eker Andre P. M. , Yasui Akira
Published: January 2008

Abstract— The Anacystis nidulans photolyase gene inserted in an expression vector plasmid was introduced into Escherichia coli cells and the production of Anacystis photolyase protein was confirmed by reaction with antibodies raised against photolyase purified from A. nidulans cells. The Anacystis photolyase functioned in photoreactivation repair defective E. coli cells. The E. coli transformants exhibited an action spectrum with a maximum around 380 nm similar to that of E. coli photolyase in contrast with the action spectrum of A. nidulans cells which has a maximum at 437 nm. These results indicate that the Anacystis photolyase produced in E. coli cells has enzymatic activity in spite of the apparent lack of its intrinsic 8‐hydroxy‐5‐deazaflavin cofactor.
SOLAR ULTRAVIOLET RADIATION AT THE EARTH'S SURFACE
Authors: Frederick J. E. , Snell H. E. , Haywood E. K.
Published: January 2008

The biologically effective ultraviolet irradiance at the earth's surface varies with the elevation of the sun, the atmospheric ozone amount, and with the abundance of scatterers and absorbers of natural and anthropogenic origin. Taken alone, the reported decrease in column ozone over the Northern Hemisphere between 1969 and 1986 implies an increase in erythemal irradiance at the ground of four percent or less during summer. However, an increase in tropospheric absorption, arising from polluting gases or particulates over localized areas, could more than offset the predicted enhancement in radiation. Any such extra absorption is likely to be highly regional in nature and does not imply that a decrease in erythemal radiation has occurred on a global basis. The Antarctic ‘ozone hole’ represents a special case in which a portion of the earth has experienced ultraviolet radiation levels during spring that are far in excess of those which prevailed prior to the present decade.
RADICAL PROCESSES IN LIPIDS. SELECTIVITY OF HYDROGEN ABSTRACTION FROM LIPIDS BY BENZOPHENONE TRIPLET
Authors: MARKOVIC D. Z. , PATTERSON L. K.
Published: January 2008

Abstract

Laser photolysis techniques have been used to measure the reactivity of benzophenone triplet (BZP) toward various fatty acids and two glycerides in benzene solution. Eight compounds varying both in number and in the configuration of olefinic bonds have been examined. It has been found that the rate constant for hydrogen abstraction from these compounds by 3BZP may be related to the number of secondary, allylic and doubly allylic hydrogens in each molecule by the equation:

k
H={0.023[Hsec+ 0.112[Hallylic] + 1.78[Hddoubly allylic]}× 107M‐1s‐1
KINETICS and THERMODYNAMICS OF THE AUTOXIDATION OF REDUCED FLAVIN MONONUCLEOTIDE (FMN)
Authors: Lind Johan , Merenyi Gabor
Published: January 2008

Abstract— Pulse radiolysis of flavin mononucleotide (FMN) solutions produce flavin semiquinone radicals. The equilibrium constant of radical formation was determined in the pH range2–7 as a function of flavin concentration. Several complex constants as well as the kinetics of equilibration were measured in this pH regime. The rate constant of the autoxidation of the free flavin mononucleotide semiquinone radical was determined to be (1 ± 0.5) × 104M−1 s−1. It is shown that between pH 2 and 7 the direct reaction of the dihydroflavin with oxygen is negligibly slow compared to the rate of autocatalysis. The autoxidation of dihydroflavin is discussed in relation to electron transfer theory.
PHOTOSENSITIVE PHENOMENA OF NITRILE HYDRATASE OF Rhodococcus sp. N‐771
Authors: Nagamune Teruyuki , Kurata Hideyuki , Hirata Makoto , Honda Jun , Hirata Akira , Endo Isao
Published: January 2008

Abstract— When the washed cells of Rhodococcus sp. N‐771 were incubated at 5°C in the dark under aerobic condition, their nitrile hydratase was inactivated after several days. Most of this activity was recovered by light irradiation. The speed of inactivation in the dark was affected by incubation temperature and amount of oxygen supply. Under anerobic conditions, however, this reversible dark inactivation was not observed; the photoirradiation of the cells irreversibly inactivated the initial cell activity by about 15%. The enzyme activity of the cell‐free extract of the inactivated cells can also be recovered when photoirradiated. This process did not require oxygen, and was not prevented by dialysis. However, the enzyme of the cell‐free extract could not be inactivated by dark, aerobic incubation nor by photoirradiation after dark anaerobic incubation.
ORIENTATION MOVEMENTS OF CHLOROPLASTS IN Vallisneria EPIDERMAL CELLS: DIFFERENT EFFECTS OF LIGHT AT LOW‐ and HIGH‐FLUENCE RATE*
Authors: Izutani Yasuhiko , Takagi Shingo , Nagai Reiko
Published: January 2008

Abstract— Epidermal cells of Vallisneria gigantea have a large central vacuole which is surrounded by a thin layer of cytoplasm. The chloroplasts are distributed over all six cytoplasmic layers of an approximate cuboid. In low‐intensity light, the accumulation of chloroplasts in the side facing the outer periclinal wall (the P side) continues for several hours. Red light (650 nm) shows the highest effect and induces such an accumulation even at a fluence rate of only 0.02 W/m2. In response to high‐intensity light, the chloroplasts move to the sides that face the anticlinal walls (the A sides) within a few tens of minutes. Blue light (450 nm) is most effective in inducing this movement. At a fluence rate of 1.51 W/m2, the reaction is induced in only half of the specimens. Neither red nor blue light can induce any orientation movement in the presence of 100 μg/ml of cytochalasin B.

The chloroplast movements in the P side have been examined with a time‐lapse video system. When cells, in which the chloroplast accumulation has been completed after red‐light irradiation, are subsequently irradiated with blue light, the rapid movement of chloroplasts to A sides is induced. However, a considerable number of chloroplasts remains in the center of the P side. The same is true of cells in which the chloroplasts have not accumulated in the P side because of cytochalasin B treatment during red‐light irradiation, when such cells are irradiated with blue light after removal of the drug. Some anchoring mechanism seems to work in low‐intensity light to render the chloroplasts immobile in the P side.
PHOTOPHYSICS and PHOTOCHEMISTRY OF BIS‐2‐(9‐ANTHRYL)ETHYL GLUTARATE
Authors: Fox Marye Anne , Britt Phillip F.
Published: January 2008

Abstract— The photochemistry and photophysics of bis‐(2‐(9‐anthryl)ethyl glutarate 2 and 2‐(9‐anthryl) ethyl pivalate 3 have been examined as monomeric models for poly‐2‐(9‐anthryl)ethyl methacrylate 1. The absorption and excitation spectra of 2 show no ground state interaction, but appreciable monomer (51%) and excimer (49%) emission. Delayed monomer and excimer fluorescence are also observed in fluid solution at room temperature. Photolysis of 2 at low temperature produces a photoproduct (44% yield) which is unstable at room temperature and presumably is the head‐to‐head (H‐H) dimer. Steady state irradiation of 2 at room temperature (Λ 350 nm) cleanly produces a head‐to‐tail (H‐T) dimer (6) derived from the singlet state and an additional unidentified adduct (7). The product distribution is concentration dependent, with 6 predominating at high concentrations (> 10−3M). The fluorescence spectra of the broken dimers derived from 6 and 7 indicate that substantial ir overlap exists in the transition state leading to each product.
DITHIONITE TREATMENT OF FLAVINS: SPECTRAL EVIDENCE FOR COVALENT ADDUCT FORMATION and EFFECT ON in vitro BACTERIAL BIOLUMINESCENCE
Authors: Mager Humphrey I. X. , Tl Shiao‐Chun
Published: January 2008

Abstract— Intrigued by the apparent requirement of dithionite for FMN reduction (as opposed to photoreduction or catalytic hydrogenation) in the H2O2‐initiated bacterial bioluminescence reaction, we chose 5‐ethyl‐3‐methyllumiflavinium cation I as a mode) to investigate possible flavin adduct formation by treatment with dithionite or (bi)sulfite. In the range of pH5–8, the reaction of dithionite with 5‐ethyl‐3‐methylIumiflavinium cation, which is in equilibrium with the 5‐ethyl‐4a‐hydroxy‐3‐methyl‐4a, 5‐dihydrolumiflavin pseudobase II (X = OH), is not limited to the formation of flavo‐semiquinone and dihydroflavin following two one‐electron steps. Several parallel and sequential reactions may take place involving the intermediacy of covalent flavin adducts. Addition of (bi)sulfite gave a 4a‐sulfiteflavin adduct II (X = SO3). Consistent with the S2O4 ⇄ 2 SO2 equilibrium, the reaction of dithionite and II (X = OH; SO3) gave rise to two flavin adducts in competitive nucleophilic displacements: a 4a‐sulfoxylate‐flavin radical (II, X = SO2) and a 4a‐dithioniteflavin adduct (II, X = S2O4), respectively. On increasing the (S2O4, SO2)/f1avin ratio under N2, the formation of the 4a‐sulfoxylate‐flavin radical became predominant. The II (X = SO2) so formed was in equilibrium with the flavosemiquinone and bisulfite and can be trapped by reacting with hydroxylamine. In the initial presence of oxygen, II (X = SO2) was highly reactive toward O2, giving a fast oxidation to II (X = SO3) and effectively suppressing the formation of the flavosemiquinone. If the oxygen is subsequently removed, the II (X = SO3) so formed then reacts with dithionite leading to quantitative accumulation of II (X = S2O4). Slow, spontaneous decompositions of the 4a‐dithioniteflavin adduct indicated the occurrence of alternative pathways, probably proceeding via a 4a‐sulfoxylateflavin anion (II, X = SO2) and II (X = SO2) as intermediates. The implications of these findings for the reactions of (bi)sulfite and dithionite with (dihydro)flavodoxins and for the role of dithionite in the H2O2 induced bacterial bioluminescence are discussed.
THE RATES OF PHOTOLYSIS OF THE FOUR INDIVIDUAL TRYPTOPHAN RESIDUES IN UV EXPOSED CALF γ‐II CRYSTALLIN
Authors: Tallmadge D. H. , Borkman R. F.
Published: January 2008

Abstract— Aqueous buffer solutions of the lens protein bovine γ‐II crystallin were irradiated at 295 nm in the presence of dithiothreitol to determine the individual photolysis susceptibilities of the four tryptophan residues. Reverse‐phase high performance liquid chromatography was utilized to compare the tryptic peptide maps before and after irradiation. Sequence analysis of collected tryptic peptides showed that the four tryptophans in calf γ‐II crystallin, TRP‐42, TRP‐68, TRP‐131, and TRP‐157 appeared in four distinct tryptic peptides. Fluorescence and absorption (diode array) monitoring of the eluting peptides allowed assessment of the changes in peptide absorbance and fluorescence following irradiation. Tryptophan fluorescence losses of (40 ± 15)%, (17 ± 4)%, (35 ± 5)% and (15 ± 4)% were observed for the peptides containing TRP‐42, TRP‐68. TRP‐131 and TRP‐157, respectively. Thus the four tryptophans in calf γ‐II crystallin did not all photolyze at the same rate. The rate differences are presumably related to the microenvironments of the individual tryptophan residues, and this is discussed in terms of the known crystal structure of calf γ‐II crystallin.
RELATIONSHIP BETWEEN PHYTOCHROME PHOTOCONVERSION and RESPONSE
Authors: Hecht Ursula , Mohr Hans
Published: January 2008

Abstract— The action of phytochrome on appearance of NADH‐dependent glutamate synthase (NADH‐GOGAT) and ferredoxin‐dependent glutamate synthase (Fd‐GOGAT) was studied in the cotyledons of the mustard (Sinapis alba L.) seedling. It was found that the [Pfr]‐response curves are composed of two branches with two very different slopes (a1 a2). This explains the biphasic fiuence response curves reported previously. While a, is the same with both enzymes, a, is much higher in NADH‐GOGAT than in Fd‐GOGAT. However, the transition from the high (a1) to the low (a1) slope occurs at the same Pfr/Ptot ratio irrespective of the steepness of a1 While the appearance of NADH‐GOGAT is very sensitive to small amounts of Prr (high a1), the response is not sensitive to the “High Irradiance Reaction” (HIR) of phytochrome. On the other hand, appearance of Fd‐GOGAT (relatively low a1) exhibits the usual HIR. It is concluded that the presently available models of phytochrome action, including the dimeric model, are not adequate to account for the actual data. At present it appears that a multiplicity of primary actions of phytochrome exist, and that it is the availability of the primary reactant (X, 1,2,3) which determines transduction or non‐transduction of the phytochrome signal.
PHOTOPHYSICAL STUDIES OF LOCAL ANESTHETICS, TETRACAINE and PROCAINE: DRUG AGGREGATIONS
Authors: Mertz C. J. , Marques A. D. S. , Williamson L. Neil , Lin C. T.
Published: January 2008

Abstract— The effects of solvent and concentration on the photophysical properties of tertiary amine local anesthetics, tetracaine and procaine were studied experimentally using low temperature (77 K) emission spectroscopy and confirmed theoretically using a HAM/3 method. For tetracaine free base in methylcyclohexane, a broad fluorescence band observed at ˜375 nm for concentrations greater than 1 × 10−3M is assigned to the molecular self‐associated species. The disappearance of this band in ethanol (i.e. a model hydrophobic environment) indicates a greater tendency of neutral tetracaine towards molecular hetero‐association. In an aqueous solution of procainc‐HCl, a broad emission band centered at ˜400 nm is detected even at a concentration as low as 1 × 10−4M and is attributed to the charged aggregates of procaine‐HCI. Two general observations for procaine, tetracaine and dibucaine are noted: (1) the monocation and free base local anesthetics in ethanol solutions give identical photophysical properties, suggesting that the monocation drug species in ethanol is H+ dissociative. and (2) the lowest singlet excited state of neutral local anesthetics is calculated to have a charge‐transfer character originating from a non‐bonding electron in the N of tertiary amine group to the π* orbital of aromatic ring. The possible pharmacological implications of the deprotonation, the drug aggregations and the charge‐transfer excitations of local anesthetics on the molecular basis of anesthesia are discussed.
OXYGEN DIFFUSION THROUGH HORSERADISH PEROXIDASE
Authors: Brunet Juan E. , Jullian Carolina , Jameson David M.
Published: January 2008

Abstract— The quenching by molecular oxygen of the fluorescence from a protoporphyrin IX adduct of horseradish peroxidase has been investigated using both intensity and time‐resolved techniques. The bimolecular quenching rate constant determined for this process, as evaluated by the conventional Stern‐Volmer analysis, was 2 × 108 M−1 s−1, among the lowest observed for protein systems. This result suggests that the heme binding site in horseradish peroxidase is relatively inaccessible to oxygen, which may account for the observation of room temperature phosphorescence in aerated solutions from enzymatically created triplet states.
BLUE LIGHT PHOTORECEPTION IN Neurospora ORCADIAN RHYTHM: EVIDENCE FOR INVOLVEMENT OF THE FLAVIN TRIPLET STATE
Authors: Fritz Bernhard J. , Kasai Sabu , Matsui Kunio
Published: January 2008

The mechanism of the photoreceptor acting on the circadian conidiation rhythm of Neurospora crassa was studied, with the following results: (1) the efficiency of 8‐haloflavins as sensitizers increased with their triplet yields. (2) Phase shifts were not abolished by removal of oxygen prior to illumination. (3) Oxygen inhibited phase shifts when introduced into the cultures after light treatment. It is proposed that the blue light photoreceptor for the circadian clock of Neurospora crassa acts (1) from its triplet state, but (2) not via singlet oxygen; (3) signal transduction involves (an) oxygen‐sensitive intermediate(s).
CHARACTERIZATION OF RADICAL ADDUCTS FORMED DURING PHOTOCHEMICAL SPIN TRAPPING IN LIPOSOMES
Authors: Sheng Pei‐GEN , Feix J. , Kalyanaraman B.
Published: January 2008

Abstract—

There exists an urgent need to monitor radical reactions in biological membranes. With the exception of a few studies in model and natural membranes, most biological spin trapping reactions have been confined to homogeneous media. In the present work we have devised a methodology by which spin trapping reactions can be investigated in liposomes composed of a fully‐saturated phospholipid, dimyristoylphosphatidylcholine. Using photochemical spin trapping, we have detected and characterized the formation and partitioning of spin adducts in liposomes. Benzophenone (a lipid‐soluble photosensitizer) and benzoyl peroxide (a lipid‐soluble radical initiator) have been used to generate free radicals from hydrogen donors during photolysis in liposomes. Both water‐soluble and lipid‐soluble spin traps have been used to trap the radicals.