bluuebunny/crossref_metadata_2025_split huggingface dataset:
AN ACTION SPECTRUM FOR CELL KILLING AND PYRIMIDINE DIMER FORMATION IN CHINESE HAMSTER V‐79 CELLS
Authors: Rothman R. H. , Setlow R. B. 
Published: January 2008

Abstract—We have determined action spectra for pyrimidine dimer formation and loss of colony‐forming ability in Chinese Hamster V‐79 cells and have found a very strong correlation between the two. These data are consistent with the notion that damage to DNA is the principle cause of cell death and that the most important type of damage is the pyrimidine dimer. While the shape of the V‐79 spectra mimics that of action spectra for bacteria. phage, and purified DNA, V‐79 cells are about twice as sensitive to radiation at long wavelengths, relative to the sensitivity at 265 nm. However, if the action spectra are normalized to 297 nm. a wavelength included in the solar spectrum, the two sets of action spectra would coincide at wavelengths relevant to human skin‐cancer. Thus an action spectrum based on microorganisms should be adequate for extrapolation to humans in terms of risk due to ozone depleteion.
A UNIQUE ALDEHYDE CHEMILUMINESCENCE INVOLVING PEROXIDE AND COPPER I IN ACIDIC DMSO
Authors: Rudie Noel G. , Wampler John E. 
Published: January 2008

Abstract—Simple aliphatic aldehydes, when mixed with hydrogen peroxide in acidic, aprotic solvents containing copper I, chemiluminesce weakly. The reaction is very specific for copper I. Quantum yield determinations reveal a catalytic role for copper I and a 1:1 stoichiometry for aldehyde and hydrogen peroxide. Kinetics reveal that an aldehyde/peroxide adduct is the active compound and synthetic l‐hydroxy octyl hydroperoxide is completely active in the reaction. Similarities in substrates. kinetics and insensitivity to extraneous substances suggest this reaction as a model for earthworm bioluminescence.
CROSS‐LINKING OF MEMBRANE PROTEINS AND PROTOPORPHYRIN‐SENSITIZED PHOTOHEMOLYSIS*
Authors: Lamola A. A. , Doleiden F. H. 
Published: January 2008

Abstract— Irradiation of protoporphyrin‐sensitized red cells with blue light in the presence of oxygen alters many components of their membranes and eventually leads to hemolysis. Extensive cross‐linking of membrane proteins can be observed before hemolysis occurs (Girotti, 1976).Facile oxidative hemolysis can be achieved without observable cross‐linking of membrane proteins upon incubation (37°C) of red cells containing membrane‐bound 3ß‐hydroxy‐5α‐hydroperoxy‐△6‐cholcstene. Thus, protein cross‐linking is not obligatory for oxidative lysis. Deoxygenation by Ar bubbling strongly retards the light‐induced increase in osmotic fragility and strongly inhibits eventual hemolysis of protoporphyrin‐sensitized erythrocytes. However, similar reduction in oxygen concentration only partially inhibits cross‐linking of membrane proteins. These results suggest that membrane protein cross‐linking and photohemolysis are not coupled processes.
STEREOELECTRONIC PROPERTIES OF PHOTOSYNTHETIC AND RELATED SYSTEMS—VI. AB INITIO CONFIGURATION INTERACTION CALCULATIONS ON THE GROUND AND LOWER EXCITED SINGLET AND TRIPLET STATES OF ETHYL BACTERIOCHLOROPHYLLIDE‐a AND ETHYL BACTERIOPHEOPHORBIDE‐a‡
Authors: Petke J. D. , Maggiora Gerald M. , Shipman Lester L. , Christoffersen Ralph E. 
Published: January 2008

Abstract— Ab initio quantum mechanical calculations on ethyl bacteriochlorophyllide‐a (Et‐BChl‐a) and ethyl bacteriopheophorbide‐a (Et‐BPheo‐a) are presented, including self‐consistent‐field (SCF) molecular orbital studies on the ground states using the molecular fragment procedure, and configuration interaction (CI) calculations on the low‐lying singlet and triplet states and absorption spectra.A characterization and comparison of many of the higher‐lying molecular orbitals obtained from the SCF studies is presented. The estimated first ionization potentials are 5.66 and 5.97 eV for Et‐BChl‐a and Et‐BPheo‐a, respectively.Excited state calculations show that the visible spectrum of both molecules consists of an intense, y‐polarized S1← S0 transition and a weakly‐allowed, x‐polarized S2← S0 transition. Both S1 and S2 states are 1(π, π*) in character, and are described by a four‐orbital model. Transitions to the remaining calculated states, S3‐S12, appear in the Soret region of the spectrum of both molecules. However, only transitions to S9(‘x’), S10(‘x’) and S11(‘y’) of Et‐BChl‐a, and S7(‘x’) and S10(‘y’) of Et‐BPheo‐a are of high intensity. The composition of the high intensity Soret states is 1(π, π*) and strongly “four‐orbital” in nature.The lowest triplet state, T1, is predicted to lie 9752 cm‐1 and 7880 cm‐1 above S0 for Et‐BPheo‐a and Et‐BChl‐a, respectively. In each molecule T2 and S1 are nearly degenerate, suggesting a favorable pathway for intersystem crossing. Calculated Tn← T1 transitions indicate that the y‐polarized T12← T1 transition in Et‐BChl‐a corresponds to the observed intense 24,400 cm‐1 absorption in the triplet‐triplet spectrum of BChl‐a. A similar type spectrum is also predicted for BPheo‐a.
LECTIN RECEPTORS ON ROD AND CONE MEMBRANES
Authors: Bridges C. D. B. , Fong S.‐L. 
Published: January 2008

Abstract— The oligosaccharides of rod and cone membranes were investigated with the aid of fluorescence and 125I‐labeled lectins. Additionally, the ability of lectins to cause agglutination in rod outer segment (ROS) suspensions was used as an index for the presence of the corresponding lectin receptors. The specificities of lectin‐ligand interactions were determined from studies of inhibition by various haptene sugars. The membranes of both rods and cones have receptors for Con A, PNA, RCA‐120, RCA‐60, SBA and WGA. The affinity of PNA for accessory cones is much higher than for the principal cones. There do not appear to be receptors for UeA and LTA on rods or cones. Additionally, receptors for HPA and DBA were identified on ROS. These results suggest the existence of the following sugar residues:The binding of Con A and WGA to ROS membrane proteins electrophoresed on SDS‐polyacrylamide gels was also investigated. In addition to rhodopsin, these lectins also bind to the 291000‐dalton protein, indicating that it is a glycoprotein containing mannose and GlcNAc.
PHOTOTOXIC EFFECTS OF NATURALLY OCCURRING POLYACETYLENES AND α‐TERTHIENYL ON HUMAN ERYTHROCYTES
Authors: Wat C.‐K. , MacRae W. D. , Yamamoto E. , Towers G. H. N. , Lam J. 
Published: January 2008

Abstract—Hemolysis, K+ leakage and acetylcholinesterase (AChE) inhibition in human erythrocytes were observed with certain naturally occurring polyacetylenes and a thiophene derivative, α‐terthienyl. K' leakage, subsequent hemolysis and AChE inactivation by phenylheptatriyne (PHT), a phototoxic compound, were considerably enhanced by UV light (312–400 nm). The same was true with α‐terthienyl and with certain other polyacetylenes. Oxygen enhanced AChE inactivation and hemolysis with α‐terthienyl in light. With PHT, only AChE inhibition was significantly enhanced in oxygen. Falcarindiol, a non‐phototoxic polyacetylene, did not inactivate this enzyme but caused hemolysis in the dark. Inhibition of AChE and hemolysis by these compounds appear to be unrelated phenomena. These results indicate that certain polyacetylenes are capable of damaging biological membranes in light, and others in dark.
LIGHT ABSORPTION AND ENERGY TRANSFER IN POLYENE‐PORPHYRIN ESTERS*
Authors: Dirks Gary , Moore Ana L. , Moore Thomas A. , Gust Devens 
Published: January 2008

Abstract—Two examples of a new class of compounds, polyenes covalently linked to meso‐tetraarylporphyrins, have been prepared. Optical studies revealed that energy transfer from a 26 π electron polyene moiety to the porphyrin was zero, whereas energy transfer efficiency from a polyene containing 18 π electrons was ˜80%. The results demonstrate that the polyene moiety can function as an efficient light gathering antenna for possible application to porphyrin‐based solar energy conversion schemes. In addition, such polyene‐porphyrin esters may serve as probes of the structural requisites for light harvesting by carotenoids in the photosynthetic membranes of green plants.
THEORETICAL STUDY OF OPTICAL SPECTRA AND CONFORMATION OF THE CHROMOPHORE OF HYPSORHODOPSIN
Authors: Kakitani Toshiaki , Kakitani Hiroko 
Published: January 2008

Abstract—Optical spectra of hypsorhodopsin were theoretically analyzed by assuming the unprotonated all‐trans form of the Schiff base of the chromophore. The large bathochromic shift of the optical absorption of hypsorhodopsin from that of the retinylidene Schiff base in solution could be easily explained by twisting the double bond of the chromophore; it could not be explained by simple counter anion models. Using the same twisted chromophore conformation for hypsorhodopsin as that of bathorhodopsin obtained by the torsion model, we showed that the calculated absorption wavelength was in fairly good agreement with the experimental value. Our calculated oscillator strengths and rotational strengths were quite similar between hypsorhodopsin and bathorhodopsin. Those theoretical results will be useful when one examines the relation of the chromophore's conformation between hypsorhodopsin and bathorhodopsin experimentally.
OBSERVATION OF THE PICOSECOND TIME‐RESOLVED SPECTRUM OF SQUID BATHORHODOPSIN AT ROOM TEMPERATURE
Authors: Suzuki Kaori , Kobayashi Takayoshi , Ohtani Hiroyuki , Yesaka Hiroshi , Nagakura Saburo , Shichida Yoshinori , Yoshizawa Tôru 
Published: January 2008

Abstract—Difference spectra between squid rhodopsin and its bathorhodopsin at room temperature were measured ca. 150 ps and ca. 500 ps after the excitation at 347.2 nm by a double‐beam picosecond time‐resolved spectrometer. The spectra measured showed a red shift of the isosbestic point between squid rhodopsin and its bathorhodopsin and a lower ΔAmax/ΔAmin value compared with those measured at low temperatures by conventional spectrophotometry.
PHOTOREACTIVATING ENZYME FROM STREPTOMYCES GRISEUS—IV. ON THE NATURE OF THE CHROMOPHORIC COFACTOR IN STREPTOMYCES GRISEUS PHOTOREACTIVATING ENZYME
Authors: Eker A. P. M. , Dekker R. H. , Berends W. 
Published: January 2008

Abstract— A structure for the chromophoric part of the intrinsic cofactor of Streptomyces griseus photo‐reactivating enzyme is suggested on the basis of absorption and fluorescence spectra of cofactor and reference compounds at various pH. The essential chromogenic part of this cofactor is proposed to be a 7,8‐didemethy]‐8‐hydroxy‐5‐deazaflavin derivative (Ia).From whole S. griseus cells a compound SF420 (Ic) was isolated which contains the same chromophoric group. This compound sensitizes the splitting of thymine dimers when irradiated with blue light, supporting the structure proposed for the photoreactivating enzyme cofactor.
ACTION SPECTRA FOR MODIFICATION OF ESCHERICHIA COLI B/r MENAQUINONE BY NEAR‐ULTRAVIOLET AND VISIBLE RADIATIONS (313–578 nm)*
Authors: Madden J. J. , Boatwright D. T. , Jagger J. 
Published: January 2008

Abstract–Menaquinone‐8 (MQ‐8) was irradiated in vivo in Escherichia coli B/r and in vitro after extraction from E. coli B/r, using monochromatic radiation in the range 313–578 nm. Within experimental error, the action spectra for loss of chromatographic mobility after irradiation in vivo and in vitro agree with each other and with the absorption spectrum of pure MQ‐8. The MQ‐8 is extremely sensitive to near‐UV light (300–380 nm), showing an F37in vivo at 334 nm of 1.3 kj/m2, a value 15 times lower than that required for growth delay, and 150 times lower than that for killing, of E. coli B/r. The quantum yield for this reaction in vivo at 334 nm has the very high value of 0.26. The high sensitivity of MQ‐8 suggests involvement in near‐UV‐induced effects on the plasma membrane.
KINETICS AND MECHANISM OF PHOTO‐INDUCED METHYL VIOLOGEN REDUCTION WITH ZINC‐MESO‐TETRAPHENYLPORPHYRINTRISULFONIC ACID AND HYDROGEN EVOLUTION FROM WATER HYDROGENASE
Authors: Okura Ichiro , Takeuchi Makoto , Kim‐Thuan Nguyen 
Published: January 2008

Abstract— The formation of the cation radical of methyl viologen was established when an aqueous solution containing zinc‐meso‐tetraphenylporphyrintrisulfonic acid, methyl viologen and mercaptoethanol was irradiated by visible light. The reduction of methyl viologen has been studied kinetically and the reduction rate expressed as followswhere [Zn]0 is the total amount of zinc compounds in the system.On the basis of the rate expression, the reaction mechanism is discussed.On the addition of hydrogenase to the above photoirradiation system, hydrogen evolution was observed by both the irradiation of sunlight and a tungsten lamp.
PHOTOREACTION OF THE ACIDIFIED FORM OF BACTERIORHODOPSIN AND ITS 9‐CIS DERIVATIVE IN PURPLE MEMBRANE AT LOW TEMPERATURES
Authors: Maeda Akio , Iwasa Tatsuo , Yoshizawa Tǒru 
Published: January 2008

Abstract— The photoreaction of the acidified form of bacteriorhodopsin and its 9‐cis derivative was studied by low temperature spectroscopy.A short exposure of the acidified form of bacteriorhodopsin, which was prepared by adding 2 mM HC1 to purple membrane suspension in 67% glycerol at 0°C, to red light at – 72°C resulted in the blue‐shift of the spectrum. The feature of the shift was very similar to that accompanied by the formation of stable 9‐cis acidified form of bacteriorhodopsin at 0°C, but only 13‐cis‐ and all‐trans‐retinals were found in the extract from this product. No blue‐shifted product was found on irradiation at – 190°C.Irradiation of the 9‐cis form of acidified bacteriorhodopsin at ‐72°C with blue light caused the isomerization of its 9‐cis‐retinylidene chromophore to 13‐cis and all‐trans forms without a significant spectral change. It became greater only after the sample was warmed above – 24°C. These results indicate the presence of the light‐induced product which has trans configuration on the 9‐10 double bond and exhibits the 9‐cis type spectrum.
RELATION BETWEEN SOME PHOTOBIOLOGICAL PROPERTIES OF FUROCOUMARINS AND THEIR EXTENT OF SINGLET OXYGEN PRODUCTION
Authors: De Mol N. J. , Beijersbergen van Henegouwen G. M. J. 
Published: January 2008

Abstract— The production of singlet oxygen (1O2) by a series of furocoumarins with different skin sensitizing abilities has been investigated with methods already proven to be suitable to establish the ability of 8‐methoxypsoralen (8‐MOP) to generate 1O2.The following compounds: 5‐methoxypsoralen (5‐MOP), psoralen, 4,5′,8‐trimethylpsoralen (TMP) and 5,8–dimethoxypsoralen (5,8–DMOP), are able to generate 1O2 when irradiated with long–wave ultraviolet light. With the photobiologically inactive angelicin no 1O2 production has been found. The relative extent of 1O2 formation has been determined for the various furocoumarins and has been compared with literature data for the skin photosensitizing effect. The observed relation between experimental data on the one side and the literature data on the other side is discussed.
PHOTOCHEMISTRY OF RETINOCHROME
Authors: Hara Reiko , Hara Tomiyuki , Tokunaga Fumio , Yoshizawa Tǒru 
Published: January 2008

Abstract— Retinochrome is a photopigment found in the visual cells of cephalopods. It has been considered to act as a supplier of the 11‐cis‐retinal required for synthesis of rhodopsin, because its all‐trans chromophore is isomerized to 11‐cis form in the light. Light and thermal reactions of squid retinochrome were investigated by low‐temperature spectrophotometry.On irradiation with green light at liquid‐nitrogen temperature, retinochrome (λmax 496 nm, – 190°C) is converted mainly to an intermediate lumiretinochrome (λmax 475 nm, – 190°C), its chromophore being changed to 11‐cis‐retinal. On irradiation with blue light at ‐ 190°C, retinochrome is changed to a photosteady–state mixture (λmax 487 nm, – 190°C) composed mainly of retinochrome and lumiretinochrome, since lumiretinochrome is partially regenerated back to retinochrome. Similarly, irradiation of lumiretinochrome with blue light also results in the same photosteady‐state mixture, which can be completely reverted to lumiretinochrome on re‐irradiation with green light.Lumiretinochrome is stable at a wide range of temperatures from – 190°C to about – 20°C. Above – 20°C, it is further converted, thermally, into metaretinochrome (λmax 470 nm), which is the same bleached product as has been observed on irradiation of retinochrome at room temperatures. Thus, the light‐bleaching process of retinochrome is rather simple compared with that of rhodopsin.
HAEMATOPORPHYRIN‐TREATED MURINE LYMPHOCYTES: IN VITRO INHIBITION OF DNA SYNTHESIS AND LIGHT‐MEDIATED INACTIVATION OF CELLS RESPONSIBLE FOR GVHR*
Authors: Canti Gianfranco , Marelli Ornella , Ricci Laura , Nicolin Angelo 
Published: January 2008

Abstract— It has been known that haemoatoporphyrin derivative (Hpd) has a preferential distribution in tissues with high mitotic index. Furthermore, cytocidal activity of light activated Hpd within the cells has been exploited in the therapy of experimental and human cancer. It is reported here that maximum, long lasting, although reversible, inhibition of DNA synthesis was obtained in Hpd‐treated lymphocytes. However, Hpd‐treated lymphoid cells did not stimulate allogeneic lymphocytes in the primary mixed lymphocyte reaction (MLR) culture. Phytohaemagglutinin (PHA) stimulated murine lymphocytes treated with Hpd and exposed to laser light have shown higher susceptibility to lysis than resting, PHA unstimulated, lymphocytes. In vitro DBA/2 stimulated C57 lymphocytes, inoculated into X‐irradiated BD2F1 mice, upon Hpd treatment followed by exposure to light, did not cause a lethal graft vs. host reaction (GVHR).Haematoporphyrin derivative was preferentially incorporated by large and metabolically active cells. inhibited the incorporation of [3H]‐thymidine in the lymphocyte nucleus and could be exploited to selectively remove blast cells from resting lymphocytes.
IN VITRO SYNTHESIS OF PHYTOCHROME APOPROTEIN DIRECTED BY mRNA FROM LIGHT AND DARK GROWN AVENA SEEDLINGS*
Authors: Gorrmann Klaus , Schaefer Eberhard 
Published: January 2008

Abstract—The aim of this work was to compare the translatability of poly‐A‐RNA from light‐ and dark‐grownArenaseedlings, the product of which should be phytochrome.Polysomal poly‐A‐RNA was isolated from 4‐day‐old dark‐grownAvenaseedlings(Avena sativaL. cv. Garry) and translated in a rabbit reticulocyte lysate system. Immunoprecipitation by anti‐phytochrome serum was used for measurements of specific phytochrome translation. Characterization of the translated and immunoprectpitated protein was performed by comparison with [35S]‐methioninein vivo‐labelled phytochrome. The specificity of the precipitation was shown by parallel use of non‐specific serum and by competitive inhibition of precipitation by exogenous unlabelled phytochrome isolated by affinity chromatography.
PRIMARY INTERMEDIATES IN THE PULSED IRRADIATION OF RETINOIDS
Authors: Lo K. K. N. , Land E. J. , TRUSCOTT T. G. 
Published: January 2008

Abstract Laser flash photolysis and pulse radiolysis have led to the characterisation of several shortlived intermediates formed after irradiation of retinoic acid and retinyl acetate in hexane or methanol.For retinoic acid, the triplet state, wavelength maximum 440 nm, extinction coefficient 7.3 × 104 dm3 mol−1 cm−1, decay constant 6.2 × 105 s−1, is formed with a quantum yield of 0.012 for 347 nm excitation. The radical cation, absorption maximum 590 nm, extinction coefficient ∼7 × 104 dm3mol−1 cm−1, is formed in a biphotonic process. The radical anion, absorption maximum 510nm in hexane, 480 nm in methanol where its extinction coefficient is 1.2 × 105 dm3mol−1 cm−1, appears to decay partially in methanol into another longer‐lived neutral radical, wavelength maximum 420 nm, by loss of OH−.For retinyl acetate, the triplet state, absorption maximum 395 nm, extinction coefficient 7.9 × 104dm3mol−1 cm−1, decay constant 1.2 × 106s−1 is formed with a quantum yield of 0.025 for 347 nm excitation. Monophotonic photoelimination of OCOCH3− in methanol produces the retinylic carbenium ion, wavelength maximum 590 nm, whose decay is enhanced by ammonia, k ∼ 2 × 106 dm3 mol−1 s−1 and retarded by water. The radical cation also has a wavelength maximum at 590 nm, its extinction coefficient being ∼ 1.0 × 105 dm3mol1 cm−1. The long‐lived transient absorption with maximum at 385 nm, extinction coefficient 1.0 × 105 dm3mol−1 cm−1, obtained from the reaction of the solvated electron with retinyl acetate in methanol may be due to either the radical anion itself or more likely the radical resulting from elimination of OCOCH3− from this anion.These results suggest that skin photosensitivity caused by retinyl acetate might be greater than that due to retinoic acid.
DESIGN AND PERFORMANCE OF THE OKAZAKI LARGE SPECTROGRAPH FOR PHOTOBIOLOGICAL RESEARCH
Authors: Watanabe Masakatsu , Furuya Masaki , Miyoshi Yasuhiro , Inoue Yasunori , Iwahashi Isao , Matsumoto Koichi 
Published: January 2008

AbstractA computer‐operated spectrograph was recently built at Okazaki, Japan. Different specimens can be placed on a horseshoe‐shaped focal curve (10 m long) covering a wavelength range of 250 to 1000 nm so they can be irradiated simultaneously. The linear dispersion is about 0.8 nm/cm. The photon fluence rate on the focal curve is 5 x 1015. photons x cm‐2 x s‐1 at 300nm and 1 x 1016 photons x cm‐2 x s‐1 at 600 and at 900 nm. The spectral half width is 5.5 nm or less on the focal curve. The stray light content is about 10‐5 of the main peak at the peak wavelength ± 100 nm. Specimens are set in microcomputer‐controlled threshold boxes so that wavelengths, photon fluence rates, photon fluences and timing of irradiations are controlled automatically according to a pre‐programmed schedule. An optical fiber system is also provided for remote irradiations.
PICOSECOND FLUORESCENCE KINETICS OF N‐ALL‐TRANS‐RETINYLIDENE‐AT‐BUTYLAMINE
Authors: Everaert J. , Rentzepis P. M. 
Published: January 2008

AbstractFluorescence lifetimes are reported for N‐all‐trans‐retinylidene‐n‐butylamine in hexane. Picosecond resolution was obtained by excitation with a single 355‐nm pulse, 25 ps FWHM, from a passive mode‐locked YAG‐laser and detection with a high speed streak camera. The lifetime dependence on temperature and the spectral characteristics support a vibrational‐torsional deactivation model of the singlet excited state of two different conformers. Additional data in decalin are consistent with this model, while the quenching in alcoholic solutions may be supported by the solvent reorientation.
FLASH PHOTOLYSIS STUDIES OF HEMATO‐AND COPRO‐PORPHYRINS IN HOMOGENEOUS AND MICROHETEROGENEOUS AQUEOUS DISPERSIONS
Authors: Reddi E. , Jori G. , Rodgers M. A. J. , Spikes J. D. 
Published: January 2008

Abstract—This paper describes an experimental study of the photo properties of the triplet (T,) states of hematoporphyrin (HP) and coproporphyrin (CP), particularly in relation to their medium dependence and reactivity towards oxygen. Triplet‐triplet absorption spectra of HP and CP have been determined in aqueous buffer at pH = 7.4 and in water‐methanol and water‐formamide mixtures. The spectra corrected for ground state contributions show major absorption peaks near 400 nm and lesser peaks near 500 nm. Extinction coefficient measurements have been made and their dependences on solvent composition investigated. Natural lifetimes of the T1 states of HP and CP and the bimolecular quenching constants with oxygen have been determined. The quantum yields of T1 formation are ca. 0.6 in buffer rising to 0.8 and higher in predominantly organic media. Incorporation of the porphyrins into micellar phases similarly causes φT, to increase. Quantum efficiencies of O−2 and O2(lΔg) formation have been determined for HP in buffer, some binary mixtures and micellar dispersions. Superoxide yields are low and may result from photo‐ionization processes. O2(lΔg) yields are large but appear to have an unexpected dependence on the medium.