bluuebunny/crossref_metadata_2025 huggingface dataset:
THE EXCITATION OF 8‐METHOXYPSORALEN WITH VISIBLE LIGHT: REVERSED PHASE HPLC QUANTITATION OF MONOADDUCTS and CROSS‐LINKS
Authors: Gasparro Francis P. , Gattolin Paola , Olack Gerard A. , Deckelbaum Lawrence I. , Sumpio Bauer E.
Published: January 2008

Abstract— The formation of 8‐methoxypsoralen‐DNA monoadducts and cross‐links is presumed to be responsible for the efficacy of photochemotherapies that employ 8‐methoxypsoralen activated with long‐wavelength ultraviolet radiation (UVA,320–400 nm). In this report it is shown that 8‐methoxypsoralen can also be activated with visible light (419 nm). Bovine aorta smooth muscle cells were treated with 8‐methoxypsoralen (1000 ng/mL) and 419 nm light (up to 12 J/cm2). Cellular DNA was isolated, hydrolyzed using nucleolytic enzymes and then analyzed by reversed‐phase high‐performance liquid chromatography. The primary effect of using visible light instead of long‐wavelength ultraviolet radiation is a more than 10‐fold reduction in the extent of cross‐link formation. Because the extent of monoadduct and cross‐link formation has not been routinely measured in experiments in which cellular assays have been performed, it is difficult to correlate cell response to the presence of a particular type of 8‐methoxypsoralen photoadduct (monoadduct or cross‐link). Thus, the use of visible light allows the study of cells containing nearly 100% monoadducts. In addition, the reduction in cross‐link formation when visible light is used to activate the compound may also reduce the mutagenicity of 8‐methoxypsoralen and hence enhance its therapeutic efficacy.
CU(II) SENSITIZES pBR322 PLASMID DNA TO INACTIVATION BY UV‐B(280–315 nm)
Authors: Lloyd R. E. , Larson R. A. , Adair Tracy L. , Tuveson R. W.
Published: January 2008

Abstract— Copper(II), in the presence of UV‐B radiation(280–315 nm), can generate single‐strand breaks in the sugar‐phosphate backbone of pBR322 plasmid DNA. A low level of single‐strand backbone breaks occurs in the presence of Cu(II) alone, but UV‐B irradiation increases the rate by the more than 100‐fold. Concomitant with the damage to the DNA backbone is a loss of transforming activity. Oxygen is required for generation of the single‐strand breaks but not for the loss of transforming activity. A DNA glycosylase (Fpg), which participates in the repair of certain DNA nitrogenous base damage, does not repair plasmid DNA damaged by Cu(II). The hydroxyl radical scavenging compound DMSO is only somewhat effective at protecting the physical and biological properties of the DNA. These results with Cu(II) are compared to those obtained previously with pBR322 plasmid DNA in the presence of Fe(III) and UV‐A.
ROLES OF URACIL‐DNA GLYCOSYLASE AND APYRIMIDINIC ENDONUCLEASES IN THE MOLECULAR 5‐BROMO‐2′‐DEOXYURIDINE PHOTOSENSITIZATION IN Escherichia coli K‐12
Authors: Yamamoto Yoko , Fujlwarat Yoshisada
Published: January 2008

The molecular mechanism for 5‐bromo‐2′‐deoxyuridine (BrdU) photosensitization was studied in thymine‐requiring wild‐type and uracil‐DNA glycosylase (UDG)‐deficient ung mutant cells of Escherichia coli K‐12. Wild‐type cells were more sensitive to BrdU photosensitiLation than ung mutant cells. IJV induced the identica/ numbers of alkaline sucrose single‐strand breaks (SSB) in 5‐bromouracil‐DNA (BrU‐DNA) of both the wild type and ung mutant. The ung mutant cells repaired SSB almost completely, whereas the wild‐type cells with UDG produced more adverse SSB by 90 min after UV. Neutral agarose gel electrophoresis of minipreps indicated that UV induced (1) more smears of host BrU‐DNA possibly by more double‐strand breaks (DSB) and (2) a greater decline of pBR322 Form I BrU‐DNA in the wild‐type cells than the ung cells. These results indicated a greater induction of SSB by apyrimidinic (AP) endonucleases in wild‐type cells. The ung/wild ratios (=1.7–1.9) for cellular and plasmid BrdU sensitizations aftcr growth in 50% BrdU were similar. The extents of UDG‐dependent and UDG‐independent sensitizations in wild‐type cells were ∼40 and ∼60%, respectively. The xth nfo double mutant defective in both exonuclcase III and endonucleasc IV was more sensitive to BrdU photosensitization than the wild type, indicating that an excess of AP sites remaining after uracil excision in the xth nfo mutant causes a greater BrdU photosensitization than SSB by AP endonucleases in wild‐type cells. Conversely, the xth rfo ung triple mutant was more resistant to BrdU photosensitization than the xth nfo double mutant, so that UV‐induced uracil residues in the BrU‐DNA are tolerated and do not appear to be directly responsible for BrdU photosensitization.
PILOT STUDY ON LIGHT DOSIMETRY FOR ENDOBRONCHIAL PHOTODYNAMIC THERAPY
Authors: Marijnissen Johannes P. A. , Baas Paul , Beek Johan F. , Moll Jan H. van , Zandwijk Nico van , Star Willem M.
Published: January 2008

Endobronchial photodynamic therapy (EB‐PDT) using photofrin as the photosensitizer is currently being evaluated as a new treatment modality for inoperable endobronchial tumors. One of the current problems with EB‐PDT is the lack of adequate light dosimetry, which hampers proper interpretation of treatment results. In this study exploratory light dosimetry experiments were performed in plastic bronchus models using either a microlens‐tipped fiber (suitable for illumination of small superficial tumors) or a cylindrical diffuser fiber (suitable for intraluminal illumination or interstitial illumination of partially obstructing tumors). It is shown that the light fluence prescriptions of current clinical protocols yield a different fluence in tissue for each illumination modality. Depending on the actual placement of the cylindrical diffuser within the lumen, the light fluence at 5 mm depth in the homogeneous tissue model may vary by a factor of 3. The results were confirmed by in vivo experiments in the trachea of a pig. There is a possibility of enhanced tissue response by accidental hyperthermia induced during EB‐PDT. The temperature rise was therefore estimated in vivo using a rat tumor model to mimic clinical EB‐PDT. Temperature rises of at least 5°C and 10°C can be expected for intraluminal and intratumoral illumination, respectively, at 3.5 ± 1 mm depth in tissue and 400 mW/cm diffuser output. Light fluence and its distribution in the bronchus strongly depend on the geometry and the optical properties of the tissue as well as on the technique of illumination. As a result of inadequate dosimetry, significant variations in treatment response between patients may be expected.
SYNTHESIS AND PHOTOBIOLOGICAL PROPERTIES OF 4‐HYDROXYMETHYL‐4′‐METHYLPSORALEN DERIVATIVES
Authors: Zagotto G. , Gia O. , Baccichetti F. , Uriarte E. , Palumbo M.
Published: January 2008

The synthesis and the photobiological activity of two new hydroxymethyl derivatives of psoralen namely 4‐hydroxymethyl‐4′‐methyl‐ and 4‐hydroxymethyl‐4′‐methyl‐8‐rnethoxypsoralen are described. Both compounds exhibited efficient photobinding to DNA and RNA. The DNA‐photobinding process was investigated using different nucleic acid structures such as double‐helical DNA, ribosomal RNA, bacterial DNA and DNA organized in the nucleosomal arrangement. The test derivatives were able to induce cross‐links to a similar extent as 8‐methoxypsoralen (8‐MOP), used as a reference photochemotherapeutic drug. In contrast to 8‐MOP, they produced relatively high levels of lO2. Most photobiological effects (DNA synthesis inhibition, T2 phage sensitization, inhibition of tumor transmitting capacity) showed a good correlation with the extent of covalent photoaddition. On the other hand, the new 4‐hydroxymethylpsoralens were unable to induce skin erythema, in striking contrast with 8‐MOP. Thus, neither cross‐linking of the nucleic acid nor 1O2 production were coupled with skin phototoxicity in this class of compounds. The new derivatives appear to represent an important beginning to development of new active photochemotherapeutic agents devoid of undesired phototoxic side effects.
EFFECTS OF ARCTIC OZONE DEPLETION AND SNOW ON UV EXPOSURE IN FINLAND
Authors: Jokela Kari , Leszczynski Kirsti , Visuri Reijo
Published: January 2008

The increase in the UV exposure of the Finnish population associated with the combined effects of ozone depletion and snow reflection was studied with the aid of theoretical calculations based on Green's clear sky UV model. A simple formula was utilized to transform horizontal irradiances to vertical irradiances averaged over 360 azimuth angle. The model was verified with spectral and broadband measurements. The difference between the theoretical and measured UV radiation falling to horizontal surfaces was in most cases less than ±10%, and the additional error to theoretical vertical irradiances was less than ± 10%. The calculations show that the annual horizontal doses in Helsinki (60.2°N, 25°E) are about 35% higher than in Saariselkä (68.4°N, 27.5°E), but the difference is only 16% for vertical doses owing to the stronger contribution to vertical (facial) surfaces of the reflection of UV from snow. At Saariselkä, the maximum vertical irradiance at the end of April approaches the midsummer values. The ozone depletions up to 40% in February and March 1992 had no significant effect on the annual doses because the total ozone returned to normal before the UV increased to biologically significant levels.
LIGHT‐DRIVEN H2 PRODUCTION WITH PROFLAVIN AND HYDROGENASE: COMPARISON OF CYTOCHROME C3 AND METHYL VIOLOGEN AS e‐ MEDIATORS
Authors: Eng Lars H. , Lewin Mona B.‐M. , Neujahr Halina Y.
Published: January 2008

We have studied the hydrogenase‐catalyzed production of H, when either its natural electron mediator cytochrome c3 (c3) or the artificial mediator methyl viologen (MV) was reduced by illumination of proflavin (PF) in the presence of ethylenediaminetetraacetate (EDTA). The reduction rates of MV and c3 were comparable at equivalent concentrations of PF, taking into account the four redox sites of c3. However, when the concentration of c3 exceeded that of PF, the reduction rate decreased. We explain this by light quenching. In the H2‐producing system, MV was more efficient than c3 as electron mediator when the initial reaction rates were compared. However, under certain conditions with MV, the rate of H2 production decreased rapidly with time of illumination, whereas with c3 it consistently remained stable. Possible reasons for this difference are discussed.

Severe inactivation of hydrogenase was observed in the absence of the primary electron donor EDTA. It is concluded that this inactivation is caused by the excited state of PF
4‐THIOURIDINE INCORPORATION INTO THE RNA OF MONKEY KIDNEY CELLS (CV‐1) TRIGGERS NEAR‐UV LIGHT LONG‐TERM INHIBITION OF DNA, RNA AND PROTEIN SYNTHESIS
Authors: Favre Alain , Moreno Giuliana , Salet Christian , Vinzens Francloise
Published: January 2008

Monkey kidney cells (CV‐1) grown for 4 h in the presence of 0.1 mM 4‐thiouridine (s4Urd) incorporate this photoactivable uridine analog in their RNA. A minor, 5–8%, thiolated RNA fraction can be isolated from bulk RNA by affinity chromatography. This RNA fraction contains 1.5–2.5 s4Urd residues per 100 nucleotides and exhibits a broad chain length distribution ranging from 700 to 7000 nucleotides. It is essentially of nuclear origin and amounts to 30% of the RNA synthesized during exposure of cells to s4Urd. Under the same s4Urd labeling conditions, no thiolated pyrimidine residues have been detected in DNA.

Irradiation with 365 nm light (45 kJ/m2) of the cells immediately after s4Urd exposure triggers long‐term inhibition of DNA, RNA and protein synthesis accompanied by a linear decline (50% in 2 days) in the total cell mass of cultured cells. In contrast, exposure to s4Urd alone results in moderate but reversible inhibitory effects. The available data suggest that s4Urd‐induced photolesions in newly synthesized RNA such as RNA‐RNA cross‐links as well as RNA‐protein bridges are directly involved in impairment of essential cellular functions.
STIMULATION OF APPEARANCE OF EXTRAPLASTIDIC TETRAPYRROLES BY A PHOTOOXIDATIVE TREATMENT OF THE PLASTIDS*
Authors: Thomsen Björn , Oelze‐Karow Heidemarie , Schuster Christa , Mohr Hans
Published: January 2008

In the mustard seedling (Sinapis alba L.) the appearance of photodetectable phytochrome and synthesis of relatively abundant cytosolic hemoproteins (nitrite reductase, ascorbate peroxidase) are stimulated rather than impaired by a photooxidative treatment of the plastids. While the ability to synthesize protoporphyrin IX from exogenous 5‐aminolevulinic acid was preserved in the photooxidatively damaged plants, protochlorophyll and chlorophyll accumulation was no longer possible. It appears from our data that in higher plants the pathway of tetrapymole synthesis up to protoporphyrin IX is not adversely affected by a photooxidative treatment of the plastids that destroys the capacity of the organelle to synthesize chlorophyll.
SIMULTANEOUS MEASUREMENT OF PHOTOSYNTHETIC OXYGEN EVOLUTION AND CARBON DIOXIDE ASSIMILATION UNDER ANAEROBIOSIS
Authors: MacInnis J. M. , McDonald K. A. , Sigman M. E. , Greenbaum E.
Published: January 2008

Instrumentation has been developed for measuring absolute simultaneous assimilation of carbon dioxide and evolution of oxygen by photosynthetic systems in anaerobic atmospheres under flow conditions. Time‐dependent photosynthetic quotients (PSQ) have bccn obtained. A detailed description of the instrument, including how it was constructed, calibrated and uscd for photosynthesis measurements, is presented. An important factor in the measurements was a clear understanding of the response time of the instrument. As with any flow system, flow rate, forward void volume and relative position of the O2 and CO2 sensors in the gas train were crucial to performance. Response time was measured by step‐function calibrations mimicking PSQ of unity. Oxygen was generated using an in‐line electrolysis cell driven by a programmable constant current source. Carbon dioxide assimilation was mimicked with the use of a programmable electronic gas blending system. Simultaneous step functions of these two key photosynthetic parameters fully characterized the response time and sensitivity of the instrument. In this report, time‐dependent PSQ for spinach leaf disks and the microalga Scenedesmus D3 are reported. It is explicitly demonstrated that the transient approach to steady state is different for the two systems. Whereas the time‐dependent PSQ for spinach depended on illumination history and reached a steady‐state value less than 1, this was not the case for Scenedesmus.
CHLOROPHYLEPHOTOSENSITIZED ELECTRON TRANSFER BETWEEN CYTOCHROME c AND A LIPID‐MODIFIED TRANSPARENT INDIUM OXIDE ELECTRODE
Authors: Salamon Z. , Tollin G.
Published: January 2008

Both direct and chlorophyll‐photosensitized electron transfer reactions between cytochrome c and a lipid‐modified indium oxide electrode have been studied by cyclic voltammetry and photoelectrochemistry. The lipid films consisted of egg phosphatidylcholine (PC), either alone or in combination with the negatively charged surfactant dihexadecylphosphate (DHP‐), and contained varying amounts of chlorophyll. The photocurrents were either ca‐thodic, when cytochrome c was used in its oxidized form in the supporting electrolyte, or anodic when the reduced form of cytochrome c was present, with a magnitude that depended on the PC concentration and the applied voltage. Quantum efficiencies of the anodic and cathodic photocurrents reached their maxima (5% and 10/o, respectively), at an intermediate PC concentration (5 mg/mL in the membrane‐forming solution), conditions under which the diffusion‐controlled electrochemical response of cytochrome c was also maximal. Incorporation of DHP‐ into the PC film increased both the direct and chlorophyll‐photosensitized currents, presumably due to electrostatic binding of the positively charged cytochrome c to the electrode surface.
RECONSTITUTION OF ALLOPHYCOCYANIN FROM Mastigocladus laminosus WITH ISOLATED LINKER POLYPEPTIDE
Authors: Gottschalk L. , Lottspeich F. , Scheer H.
Published: January 2008

The core linker polypeptide Lc8.9 was isolated from Mastigocladus laminosus and purified on a preparative scale. A method for the reconstitution of allophycocyanin (AP)—linker complexes from isolated polypeptides was developed. The complex (αAP(βAP)3 Lc8.9 was reconstituted and compared to (αAPβAP) and (αAPβAP)3 by sucrose density gradient ultracentrifugation, absorption, fluorescence emission and circular dichroism spectroscopy. Differences in the spectra of reconstituted and of directly isolated AP complexes are discussed.
APOPTOSIS DURING PHOTODYNAMIC THERAPY‐INDUCED ABLATION OF RIF‐1 TUMORS IN C3H MICE: ELECTRON MICROSCOPIC, HISTOPATHOLOGIC AND BIOCHEMICAL EVIDENCE
Authors: Zaidi Syed I. A. , Oleinick Nancy L. , Zaim M. Tarif , Mukhtar Hasan
Published: January 2008

Abstract Very little is known about the applicability of the metabolic and biochemical events observed in cell culture systems to in vivo tumor shrinkage following photodynamic therapy (PDT). The purpose of this study was to assess whether PDT induces apoptosis during tumor ablation in vivo. We treated radiation‐induced fibrosarcoma (RIF‐1) tumors grown in C3H/HeN mice with PDT employing three photosensitizers, Photofrin‐II, chloroaluminum phthalocyanine tetrasulfonate, or Pc IV (a promising phthalocyanine developed in this laboratory). Each photosensitizer was injected intraperitoneally and 24 h later the tumors were irradiated with an appropriate wavelength of red light using an argon‐pumped dye laser. During the course of tumor shrinkage, the tumors were removed at 1, 2, 4 and 10 h post‐PDT for DNA fragmentation, histopathologic, and electron microscopic studies. Markers of apoptosis, viz. the ladder of nucleosome‐size DNA fragments, increased apoptotic bodies, and condensation of chromatin material around the periphery of the nucleus, were evident in tumor tissue even 1 h post‐PDT; the extent of these changes increased during the later stages of tumor ablation. No changes were observed in tumors given photosensitizer alone or irradiation alone. Our data suggest that the damage produced by in vivo PDT may activate endonucleolysis and chromatin condensation, and that apoptosis is an early event in tumor shrinkage following PDT.
PHOTOREACTIVATION IN A phrB MUTANT OF Escherichia coli K‐12: EVIDENCE FOR THE ROLE OF A SECOND PROTEIN IN PHOTOREPAIR
Authors: Dorrell N. , Ahmed A. H. , Moss S. H.
Published: January 2008

Abstract In Escherichia coli, the light‐dependent repair of pyrimidine dimers in UV‐irradiated DNA is now accepted as being due to enzymatic photoreactivation (PR) by a 50 kDa enzyme, photolyase (EC 4.1.99.3). The gene for this enzyme has been mapped at 16.2 min and designated phr. This gene was earlier described as phrB, another locus phrA having been proposed in association with PR. The relevance of the putative phrA gene has now been placed in doubt. The recent report of the discovery of a photoreactivating enzyme in Drosphila melanogaster. which specifically repairs pyrimidine (6–4) pyrimidone photoproducts ([6–4] photoproducts), and that E. coli does possess a protein with specific affinity for the (6–4) photoproduct, has cast new light on the prospective role of phrA in PR. We have determined the nucleotide sequence of the putative phrA gene, which suggests it codes for a protein of 38 kDa. When the putative phrA gene was cloned into an expression vector and transformed into a phrA phrB mutant of E. coli, a level of photorepair was observed, which could correspond to repair of (6–4) photoproducts.
ISOLATION OF V79 FIBROBLAST CELL LINES CONTAINING ELEVATED METALLOTHIONEIN LEVELS THAT HAVE INCREASED RESISTANCE TO THE CYTOTOXIC EFFECTS OF ULTRAVIOLET‐A RADIATION
Authors: Dudek Edward J. , Peak Jennifer G. , Roth Robert M. , Peak Meyrick J.
Published: January 2008

Abstract Isolated clones of V79 Chinese hamster lung fibroblasts, selected for resistance against cadmium toxicity, were exposed to monochromatic 365 nm ultraviolet‐A (UVA, 320 nm to visible light) radiation and examined for cell survival. All three of the Cd‐resistant V79 clones (V79Cd) tested exhibited significant increases in survival after irradiation compared with control cultures similar to the increased survival observed in Zn acetate‐induced V79 cells. Dose‐modifying factors calculated for these survival experiments were all approximately 1.5. When characterized for steady‐state levels of metallothionein (MT) mRNA and associated Cd‐binding activity, all of the Cd‐resistant V79Cd clones demonstrated elevated constitutive levels of both, implicating MT as the mechanism responsible for the observed cellular resistance to Cd and also to 365 nm UVA radiation. However, whereas levels of intracellular MT protein correlated with differences in survival against Cd, MT intracellular levels did not correlate well with protection against 365 nm UVA. Increased cell survival after exposure to 365 nm UVA radiation mediated by MT appeared to reach a threshold level and MT only provided a limited degree of protection. Since UVA radiation is known to cause cell death mediated through the intracellular generation of reactive oxygen species (ROS), these results suggest that the role of MT in ameliorating cellular photooxidative damage produced by UVA is by reducing intracellular ROS.
UV IRRADIATION OF NUCLEIC ACIDS: CHARACTERIZATION OF PHOTOPRODUCTS OF THYMIDYLYL‐(3′→5′)‐2′‐DEOXY‐5‐FLUOROURIDINE
Authors: Alderfer James L. , Soni Sunil‐D. , Arakali Aruna V. , Wallace John C.
Published: January 2008

Abstract— The acetone‐sensitized irradiation using UV‐B (ultraviolet light, 280–320 nm; sunlamps) of thymidyl‐yl(3′→5′)deoxyfluorouridine monophosphate produces two main photoproducts. The distribution of these photo‐products is dependent on the pH of the irradiation solution. At pH 6, the cis‐syn cyclobutane‐type photodimer is the major product, whereas at high pH (8–10) a photoadduct is the major product. These photoproducts have been identified and structurally characterized by H‐1 and C‐13 NMR spectroscopy. The photoadduct arises from defluorination of the 5‐fluorouracil moiety. The structure of the photoadduct maintains the sugar‐phosphate backbone of the starting material (d‐TpF), and contains a saturated thymine moiety with an added Thy(C6‐hydroxyl) and a Thy(C5)‐(C5)Ura covalent bond.
Cis/trans ISOMERIZATION OF CAROTENOIDS BY THE TRIPLET CARBONYL SOURCE 3‐HYDROXYMETHYL‐3,4,4‐TRIMETHYL‐1,2‐DIOXETANE*
Authors: Sundquist Alfred R. , Hanusch Michael , Stahl Wilhelm , Sies Helmut
Published: January 2008

Abstract— The interaction of biological carotenoids with 3‐hydroxymethyl‐3,4,4‐trimethyl‐1,2‐dioxetane (HTMD), a thermodissociable source of electronically excited ketones, was investigated using reversed‐phase high‐performance liquid chromatography. Incubation of the all‐trans isomers of β‐carotene, lycopene and canthaxanthin with HTMD led to significant trans‐to‐cis isomerization, with cis isomers accounting for 20–50% of products formed (the balance assigned as oxidation products). The isomers forming from all‐trans‐β‐carotene were identified as 9‐cis‐, 13‐cis‐ and 15‐cis‐β‐carotene by cochromatography of cis isomer standards and by on‐line diode array absorbance spectroscopy. An HTMD‐dependent cis‐to‐trans isomerization was observed in incubations started with 15‐cis‐β‐carotene, and it occurred more rapidly and to a greater extent than the isomerization of all‐trans‐β‐carotene. The isomer patterns generated from lycopene and β‐carotene are generally similar to those reported recently for various human tissues (Stahl et al, 1992, Arch. Biochem. Biophys.294, 173–177).
LOW‐TEMPERATURE LUMINESCENCE SPECTRA AND FLUORESCENCE LIFETIMES OF POLYCYTIDYLIC ACID IN POLYALCOHOLIC GLASSES
Authors: Večeř Jaroslav , Heřman Petr , Beránek Josef
Published: January 2008

Abstract— Corrected emission spectra and fluorescence lifetimes of polycytidylic acid in ethylene glycol: water glass at low temperatures are reported. Luminescence properties observed exhibit a strong dependence on pH and temperature. At neutral pH a vibronic structure of a blue part of the fluorescence spectrum is revealed when temperature is changed from 77 to 10 K, confirming that a monomer component of fluorescence is present. There is also a strong difference in decay of a red‐shifted excimer fluorescence at 10 K at pH 7 and pH 3.9, reflecting a different protonation of cytosine residues and different conformations of polynucleotides in such conditions.
UV‐A‐MEDIATED ACTIVITY OF p‐METHOXYMETHYLCINNAMATE
Authors: Ashwood‐Smith M. , Stanley C. , Towers G. H. N. , Warrington P. J.
Published: January 2008

Abstract— Methyl esters of hydroxycinnamic acids are photobiologically active. Cis(Z) and trans(E)p‐methoxymethyl‐cinnamate photosensitize Escherichia coli and Chinese hamster ovary cells. They also produce sister chromatid exchanges. Photosensitization is oxygen independent, and the cinnamates are not genetically active in the absence of light in the Ames Salmonella typhimurium test.
PERTUSSIS TOXIN SENSITIVE PHOTOAGGREGATION OF PIGMENT IN ISOLATED Xenopus TAIL‐FIN MELANOPHORES
Authors: Rollag Mark D.
Published: January 2008

Abstract— Direct illumination of Xenopus laevis tail‐fin melanophores results in rapid, reversible translocation of intracellular pigment granules to a perinuclear location, an effect distinct from and opposite to the photodispersion of pigment found in melanophores isolated from Xenopus embryos. In this report we show that both pertussis toxin and dibutyryl‐adenosine‐3', 5'‐monophosphate block the ability of light to cause photoaggregation of pigment in cultured tail‐fin melanophores, whereas dibutyryl‐guanosine‐3', 5'‐monophosphate is without effect.
PHOTODYNAMIC EFFECTS OF NEW SILICON PHTHALOCYANINES: In vitro STUDIES UTILIZING RAT HEPATIC MICROSOMES AND HUMAN ERYTHROCYTE GHOSTS AS MODEL MEMBRANE SOURCES
Authors: Zaidi Syed I. A. , Agarwal Rajesh , Eichler Guido , Rihter Boris D. , Kenney Malcolm E. , Mukhtar Hasan
Published: January 2008

Abstract— Photodynamic therapy (PDT) of cancer is a modality that relies upon the irradiation of tumors with visible light following selective uptake of a photosensitizer by the tumor tissue. There is considerable emphasis to define new photosensitizers suitable for PDT of cancer. In this study we evaluated six phthalocyanines (Pc) for their photodynamic effects utilizing rat hepatic microsomes and human erythrocyte ghosts as model membrane sources. Of the newly synthesized Pc, two showed significant destruction of cytochrome P‐450 and monooxygenase activities, and enhancement of lipid peroxidation, when added to microsomal suspension followed by irradiation with ∼ 675 nm light. These two Pc named SiPc IV (HOSiPcOSi[CH3]2[CH2]3N[CH3]2) and SiPc V (HOSiPcOSi[CH3]2[CH2]3N[CH3]31 I) showed dose‐dependent photodestruction of cytochrome P‐450 and monooxygenase activities in liver microsomes, and photoenhancement of lipid peroxidation, lipid hydroperoxide formation and lipid fluorescence in rnicrosomes and erythrocyte ghosts. Compared to chloroaluminum phthalocyanine tetrasulfonate, SiPc IV and SiPc V produced far more pronounced photodynamic effects. Sodium azide, histidine, and 2,5‐dimethylfuran, the quenchers of singlet oxygen, afforded highly significant protection against SiPc IV‐ and SiPc V‐mediated photodynamic effects. However, to a lesser extent, the quenchers of superoxide anion, hydrogen peroxide and hydroxyl radical also showed some protective effects. These results suggest that SiPc IV and SiPc V may be promising photosensitizers for the PDT of cancer.
ALTERATIONS OF PROTEOGLYCANS IN ULTRAVIOLET‐IRRADIATED SKIN
Authors: Margelin Dominique , Fourtanier Anny , Thevenin Thierry , Medaisko Chantal , Breton Monique , Picard Jacques
Published: January 2008

Abstract— The effect of UVB exposure on the distribution and synthesis of dermal proteoglycans was measured in the skin of hairless mice. Two groups of mice were included: one was irradiated for 10 weeks; the other was kept as control. After intraperitoneal injection of sodium 35S‐sulfate, punch biopsies were taken for histology and proteoglycans were extracted from the remaining skin with 4 M guanidinium chloride, containing 3–[(3‐cholamidopropyl)dimethylammonio]‐1‐propanesulfonate (0.5%, weight per volume). Following proteolytic digestion, the glycosaminoglycan constituents were isolated and analyzed by quantitative cellulose acetate electrophoresis and enzymatic digestibility.

Under the influence of UVB radiation, newly synthesized proteoglycans measured by 35SO4 uptake increased as much as 60%. In addition, the irradiated skin had a higher average content of proteoglycan than had control skin (4981 μg vs 4134 μg/g dry weight). This could be ascribed to an increase in heparin (1400 vs 533 μg/g dry weight) and heparan sulfate (472 vs 367 μg/g dry weight), whereas no change in the concentration of hyaluronic acid (1243 vs 1372 μg/g dry weight) and dermatan sulfate (1866 vs 1863 μg/g dry weight) was observed. The irradiated animals also exhibited a marked increase in the synthesis of heparan sulfate and heparin (62% and 71%, respectively). These results demonstrate that chronic doses of UVB altered proteoglycan metabolism through both quantitative and qualitative changes.
8‐METHOXYPSORALEN DNA INTERSTRAND CROSS‐LINKING OF THE RIBOSOMAL RNA GENES IN Tetrahymena thermophila. DISTRIBUTION, REPAIR AND EFFECT ON rRNA SYNTHESIS
Authors: Fengqin Xia , Nielsen Henrik , Zhen Weiping , Nielsen Peter E.
Published: January 2008

Abstract— The distribution and repair of 8‐methoxypsoralen‐DNA interstrand cross‐links in the ribosomal RNA gencs (rDNA) in Tetrahymena thermophila have been studied in vivo by Southern blot analysis. It is found that the cross‐links at a density of ≤ 1/2 × 104 base pairs (bp) are distributed equally between three domains (terminal spacer, transcribed region and central spacer) as defined by restriction enzyme analysis (Bam HI and ClaI). It is furthermore shown that a dosage resulting in approximately one cross‐link per rDNA molecule (21 kbp, two genes) is suficient to block KNA synthesis. Finally, it is shown that the cross‐links in the rDNA molecules are repaired at equal rate in all three domains within 24 h and that RNA synthesis is partly restored during this repair period. The majority of the cells also go through one to two cell divisions in this period but do not survive.
UV‐INDUCED DAMAGE OF PHOTORECEPTOR PROTEINS IN THE PARAFLAGELLAR BODY OF Euglena gracilis
Authors: Brodhun Bonita , Häder Donat‐P.
Published: January 2008

Abstract— The paraflagellar body (PFB), the putative photoreceptor for phototaxis in the flagellate Euglena gracilis, was isolated still attached to the flagellum. After solubilization the proteins were separated and analyzed by two‐dimensional gel electrophoresis. To discriminate the PFB‐specific proteins from the flagella proteins, flagella without PFB were analyzed, isolated from the flagellate Astasia longa (a chlorophyll‐free relative of E. gracilis), which has no PFB and lacks phototaxis. The absorption spectra of solubilized PFB samples showed a maximum at 415 nm, two shoulders around 380 and 410 nm and two additional small peaks at 515 and 540 nm not present in the control sample without PFB. Two‐dimensional gel electrophoresis showed eight PFB‐specific proteins with molecular masses in the range of 25000–45000 and isoelectric points in the range of pH 3.5–7. Ultraviolet radiation strongly affects some of these PFB‐specific proteins, but also flagella proteins are damaged by UV treatment. There is also a drastic decrease in the PFB‐specific absorption maxima after UV irradiation.
EFFICIENT PHOTODYNAMIC ACTION OF VICTORIA BLUE BO AGAINST THE HUMAN LEUKEMIC CELL LINES K‐562 AND TF‐1
Authors: Fiedorowicz Maciej , Galindo Jean Remy , Julliard Michel , Mannoni Patrice , Chanon Michel
Published: January 2008

Abstract— Photodynamic induced cytotoxicity by Victoria blue BO (VB‐BO), merocyanine 540 (MC540), Nile blue A (NB) and 4‐tetrasulfonatophenyl‐porphyrin (4‐TSPP) has been studied on two human leukemic cell lines: K‐562 and TF‐1. Cells were incubated with dyes and irradiated with different doses of white light. Cell survival was assessed by propidium iodide (PI) staining using flow cytometry analysis. Concentrations of 5 x 10 8M VB‐BO were found to kill 75% of cells, and a concentration of 1 × 10−7M induced more than 99% of cell killing. To obtain the same cytotoxic level, the presence of 2.6 × 10−5M of MCS40 during irradiation was needed. Under the conditions used, NB was ineflective as a photosensitizer, although uptake studies showed that this dye was taken by the cells in much greater amounts than any other studied dye. Cell cycle distribution of TF‐1 cells, surviving MC540 or VB‐BO photoscnsitization has bccn studied by flow cytometry analysis after staining with Hoechst 33342 and PI. It was found that cells in G1 phase were slightly more resistant toward MCS40– and VB‐BO‐mediated photosensitization than cells in other phascs of the ccll cycle
CHANGES IN SPECTRAL PROPERTIES OF CHLOROPHYLL DURING GREENING OF BARLEY LEAVES
Authors: Shlbasaka Mineo , Tanaka Ayumi , Tsiji Hideo
Published: January 2008

Abstract— In order to study the formation of photochemical systems in the early phase of greening of barley leaves, we examined the changes in chlorophyll (Chl) spectral components of the absorption spectrum of greening tissues using a curvc analysis method. Peak positions of the fourth‐derivative spectrum were changing during the first 30 min of illumination hut became stable thereafter. Results of curve analysis showed that about half of the spectral components of mature leaves were already found at 30 min after onset of illumination, and the rest appeared by 4 h. After 30 min the half widths of some spectral componcnts changed slightly. The 683 nm form of Chl a of the photosystem 11 (PSII) core was present after 30 min of illumination and increased up to 2 h, followed by a decrease. The 641 nm form of Chl u of photosystem I (PSI) appeared at 30 min and increased until 2.5 h. The 699 nm form of Chl a also appeared at 1.5 h. The 640 nm form of Chl b appeared at 2 h, while the 649 nm Chl b form was found earlier (1.5 h). Both components were increasing with prolonged time of illumination. Finally, the 704 nm form of Chl a characteristic of the PSI peripheral antenna appeared at 4 h of greening. Ruorescence of PSI and PSII began to appear at 1 and 2 h, respectively. These spectral changes were discussed in relation to the formation of chlorophyll‐protein complexes and the development of photochemical activities.
LIGHT EMISSION ACCOMPANIES OXYGEN UPTAKE DURING THE PEROXIDATIVE METABOLISM OF TETRACYCLINES
Authors: Gillo Virginia E. , Cilento Giuseppe
Published: January 2008

Abstract— Tetracycline molecules offer several sites for peroxidative metabolism of the type known to lead to oxygen consumption and electronic cxcitation. Accordingly, when tetracycline and chlortetracycline were exposed to horseradish peroxidase in the presence of hydrogen peroxide, oxygen was taken up and light emission was observed. The overall quantum yield ofchemiluminescencc is on the order of 10 6, but that of chemiexcitation may be orders of magnitude higher as suggested by studies of sensitized emission. Given the widespread distribution of peroxidases, the formalion of highly reactive metabolites of tetracycline may have biological importance.
UVA‐INDUCED AUTOCRINE STIMULATION OF FIBROBLAST‐DERIVED COLLAGENASE/MMP‐1 BY INTERRELATED LOOPS OFINTERLEUKIN–1 andINTERLEUKIN–6
Authors: Wlaschek Meinhard , Heinen Gudrun , Poswig Arndt , Schwarz Agatha , Krieg Thomas , Scharffetter‐Kochanek Karin
Published: January 2008

Abstract— Previous work has shown that fibroblast‐derived collagenase/matrix‐metalloproteinase‐1(MMP–1), responsible for the breakdown of dermal interstitial collagen, was dose‐dependently induced in vitro and in vivo by UVA irradiation and this induction was at least partly mediated byinterleukin–6(IL–6). We here provide evidence that UVA‐inducedIL–1α andIL–1β play a central role in the induction of the synthesis both ofIL–6 and collagenase/MMP–1. In contrast to the late increase ofIL–1α andIL–1β mRNA levels at 6 h postirradiation, bioactivity ofIL–1 is already detectable at 1 h postirradiation. This early peak ofIL–1 bioactivity appears to be responsible for the induction ofIL–6 synthesis and together withIL–6 lead to an increase of the steady‐state mRNA level of collagenase/MMP–1 as deduced from studies usingIL–1α andIL–1β antisense oligonucleotides or neutralizing antibodies againstIL–1α andIL–1β Besides the early posttranslationally controlled release of intracellularIL–1, a latter pretranslationally controlled synthesis and release ofIL–1 perpetuates the UV response. From these data we suggest a UV‐induced cytokine network consisting ofIL–1α,IL–1β andIL–6, which via interrelated autocrine loops induce collagenase/MMP–1 and thus may contribute to the loss of interstitial collagen in cutaneous photoaging.
ULTRAVIOLET DOSIMETRY IN OUTDOOR MEASUREMENTS BASED ON BACTERIOPHAGE T7 AS A BIOSENSOR
Authors: RONTÓ Gy , Gaspar S. , Gugolya Z.
Published: January 2008

A simple method has been worked out for measuring the biologically effective dose (BED) of solar radiation The method uses phage T7 as a biosensor and it includes field measurements of global and direct UV radiation from the sun in the air; it has been applied to underwater measurements as well. Results of field measurements are presented with discussion of the angle‐dependent sensitivity of the biosensor. A model of spectral irradiance based on the measured values is presented. Relevance of the HT7 unit—derived earlier by us from T7 phage inactivation upon UV radiation—as a measure of the BED is also discussed.
POLARIZED SITE‐SELECTION SPECTROSCOPY OF CHLOROPHYLL a IN DETERGENT
Authors: Kwa Stefan L. S. , Voulker Silvia , Tilly Nina T. , Grondelle Rienk van , Dekker Jan P.
Published: January 2008

Monomeric chlorophyll a (Chl a) was obtained from the isolated core antenna complex CP47 of photo‐system II after incubation with the detergent triton X‐100 and was studied by low‐temperature polarized light spectroscopy with the aim to obtain model spectra for Chi a in intact photosynthetic complexes. Evidence is presented by circular dichroism and anisotropy measurements that the isolated chlorophyll is monomeric. The absorption bandwidths are relatively large compared to those found in photosynthetic complexes due to inhomogeneous broadening introduced by the detergent. By selective laser excitation at low temperature, considerable narrowing can be achieved. A number of vibrational bands are resolved in the site‐selected, polarized absorption and fluorescence emission spectra. The emission spectrum of Chi a in detergent‐damaged CP47 is compared with that of Chi a in the intact light‐harvesting complex of photosystem II (LHC‐II) from green plants. The spectra are remarkably similar indicating that the low‐temperature thermal emitter in LHC‐II has spectral properties that are very similar to those of monomeric Chl a.
AUTHENTIC in vivo ABSORPTION SPECTRA FOR CHLOROPHYLL IN LEAVES AS DERIVED FROM in situ AND in vitro MEASUREMENTS*
Authors: Richter Thomas , Fukshansky Leonid
Published: January 2008

On the basis of a comprehensive treatment of light propagation in plant tissue the first authentic in vivo absorption spectrum of chlorophyll in a leaf (of Catalpa bignonioides) has been elucidated. An experimental‐theoretical procedure is described, which permits derivation of the authentic chlorophyll spectrum by purifying the in vivo absorption spectrum of a leaf from the distortions of optical origin: multiple scattering and distributional error. The procedure involves measurements of internal and external light fluxes, spatial characterization of tissue layers, cells, chloroplasts and grana stacks. Furthermore, one has to determine the local chlorophyll concentrations. The theories of radiation transfer and absorption statistics make up the theoretical basis of the procedure. The derived authentic chlorophyll spectrum differs both from the in vivo spectrum of the leaf and (although to a smaller degree) from the in vitro spectrum of chlorophyll‐protein complexes extracted from the same leaf.
SPECTRAL AND PHOTOCHEMICAL PROPERTIES OF CURCUMIN
Authors: Chignell Colin F. , Bilskj Piotr , Reszka Krzysztof J. , Motten Ann G. , Sik Robert H. , Dahl Thomas A.
Published: January 2008

Curcumin, bis(4‐hydroxy‐3‐methoxyphenyl)‐l,6‐heptadiene‐3,5‐dione, is a natural yellow‐orange dye derived from the rhizome of Curcuma longa, an East Indian plant. In order to understand the photobiology of curcumin better we have studied the spectral and photochemical properties of both curcumin and 4‐(4‐hydroxy‐3‐methoxy‐phenyl)‐3‐buten‐2‐one (hC, half curcumin) in different solvents. In toluene, the absorption spectrum of curcumin contains some structure, which disappears in more polar solvents, e.g. ethanol, acetonitrile. Curcumin fluorescence is a broad band in acetonitrile (λmax= 524 nm), ethanol (λmax= 549 nm) or micellar solution (λmax= 557 nm) but has some structure in toluene (λmax= 460, 488 nm). The fluorescence quantum yield of curcumin is low in sodium dodecyl sulfate (SDS) solution (φ= 0.011) but higher in acetonitrile (φ= 0.104). Curcumin produced singlet oxygen upon irradiation (φ > 400 nm) in toluene or acetonitrile (Φ= 0.11 for 50 μM curcumin); in acetonitrile curcumin also quenched 1O2 (kq, = 7 × 106 M−1 s−1). Singlet oxygen production was about 10 times lower in alcohols and was hardly detectable when curcumin was solubilized in a D2O micellar solution of Triton X‐100. In SDS micelles containing curcumin no singlet oxygen phosphorescence could be observed. Curcumin photogenerates superoxide in toluene and ethanol, which was detected using the electron paramagnetic resonance/spin‐trapping technique with 5,5‐dimethyl‐pyrroline‐.N‐oxide as a trapping agent. Unidentified carbon‐centered radicals were also detected. These findings indicate that the spectral and photochemical properties of curcumin are strongly influenced by solvent. In biological systems, singlet oxygen, superoxide and products of photodegradation may all participate in curcumin phototoxicity depending on the environment of the dye.
CYTOPROTECTION AGAINST MEROCYANINE 540‐SENSITIZED PHOTOINACTIVATION OF THE Na+,K+‐ADENOSINE TRIPHOSPHATASE IN LEUKEMIA CELLS: GLUTATHIONE AND SELENOPEROXIDASE INVOLVEMENT
Authors: Lin Fubao , Girotti Albert W.
Published: January 2008

When irradiated with broad‐band visible light in the presence of merocyanine 540 (MC540), murine leukemia L1210 cells grown under selenium‐deficient conditions (Se(‐) cells) accumulated lipid hydroperoxides and lost viability more rapidly than selenium‐satisfied controls (Se(+) cells). These findings suggest that cytoprotection against photoperoxidation and photokilling is mediated at least in part by selenoperoxidase (SePX) action. Similar protection against photoinactivation of an intrinsic membrane enzyme, the Na+,K+‐ATPase, has been observed. Thus, irradiation of MC540‐sensitized Se(‐) cells resulted in an immediate and progressive inactivation of ouabain‐sensitive Na+, K+‐ATPase; by contrast, activity loss in Se(+) cells was preceded by a prominent lag. Enzyme photoinactivation in Se(‐) cells was inhibited by ebselen, an SePX mimetic, confirming that SePX(s) is (are) involved in natural protection. Desferrioxamine treatment (iron sequestration/inactivation) resulted in higher hydroperoxide levels and slower Na+,K+‐ATPase inactivation during MC540/light exposure, whereas ferric‐8‐hydroxyquinoline treatment (iron supplementation) had the opposite effect. Thus, iron appears to play an important role in both of these processes. In contrast, photoinactivation of another intrinsic enzyme in L1210 cells, acetylcholinesterase (AChE), was unaffected by selenium or iron manipulation. On the basis of these findings, we propose that lipid peroxidation plays an important role in the photoinactivation of Na+,K+‐ATPase, but not AChE. This is consistent with the fact that Na+, K+‐ATPase's active site lies within the membrane bilayer, whereas AChE's active site lies outside the bilayer.
FORMATION OF REARRANGEMENT PRODUCT IN PHOTOLYSIS OF α,α‐DIMETHYLDEOXYBENZOIN UPON CYCLODEXTRIN COMPLEXATION
Authors: Pitchumani K. , Ramamurthy V.
Published: January 2008

Abstract Solid‐state irradiation of cyclodextrin complexes of α,α‐dimethyldeoxybenzoin results in the formation of a significant amount of rearrangement product, 4‐isopropylbenzophenone, in addition to cage products. This behavior is not observed in the photolysis in solution or in micellar media.
MEMBRANE DAMAGE IN UV‐IRRADIATED LENSES
Authors: Hightower Kenneth R. , Mccready Janet P. , Borchman Doug
Published: January 2008

Abstract The purpose of this study was to investigate three possible causes of membrane damage following UV irradiation: photooxidation of membrane thiol (SH) groups, peroxidation of membrane lipids and inhibited synthesis of membrane proteins. Thiol loss was not observed. Thin‐layer chromatography showed a four‐fold increase in several primary lipid peroxidation products such as hydroperoxyl lipids in the epithelial membrane preparations isolated from irradiated lenses. The formation of new hydroxyl lipid bands not seen in control preparations was also observed in isolated membranes from irradiated lenses. Irradiation in the presence or absence of oxygen produced lipid peroxidation products. Aerobic irradiation produced small, but statistically significant increases in lipid hydroxyls and hydroperoxyls relative to controls. Repair of initial damage might be compromised by the observed 60% reduction in rate of protein synthesis measured in lens membranes following irradiation. Synthesis was affected by means other than depleted potassium or elevated calcium levels.
STRUCTURE AND CONFORMATION OF PHOTOSYNTHETIC PIGMENTS AND RELATED COMPOUNDS 7. ON THE CONFORMATION OF THE METHYL ESTER OF (20‐METHYLPHYTOCHLORINATO)NICKEL(II)‐A BAaERIOCHLOROPHYLL c MODEL COMPOUND
Authors: Senge Mathias O. , Smith Kevin M.
Published: January 2008

Abstract The crystal and molecular structure of the title compound 4 have been determined by single crystal X‐ray crystallography. The structure shows the typical S,‐ruffled conformation observed for Ni(II) tetrapyrroles. Compared to the structure of the methyl ester of (132‐demethoxycarbonyl‐pheophorbidato a)nickel(II), 4 shows a smaller Ca‐Cm‐Cm angle and a higher degree of conformational distortion at the methyl‐substituted C20 position. This local distortion of the macrocycle might account for the bathochromic shifted absorption spectra of the bacteriochlorophylls c compared to the d‐series. Crystal data: C35H38N4NiO3; tetragonal, P43212, a = 15.335(7) Å, c = 25.11(2) Å, V = 5904, Z = 8, λ(Mo Kα) = 0.71069 Å, μ= 0.701 mm−1, P(000) = 2624, 130 K, R = 0.058 for 5700 reflections with F > 4.0σ(F).