bluuebunny/crossref_metadata_2025 huggingface dataset:
METHYLENE BLUE‐SENSITIZED PHOTOOXIDATION OF HEMOGLOBIN: EVIDENCE FOR CROSS‐LINK FORMATION*
Authors: Girotti Albert W. , Lyman Suzanne , Deziel Mark R.
Published: January 2008

Abstract— When exposed to light of wavelengths >520nm, human hemoglobin (Hb; I mg/m/ at pH X, 10°C) in the presence of methylene blue (MB) undergoes inter‐subunit cross‐linking, as visualized by sodium dodecyl sulfate (SDS)‐gel electrophoresis. With 10μM MB and a light dose of ˜700kJ/m2, a prominent ‘dimer’ band (28,00–30,000 daltons) appears, with traces of higher mol wt components. This effect (also observed by SDS‐Sepharose chromatography) is seen with dialyzed hemolysates and with chromatographically purified Hb. The sedimentation coefficient of photooxidized Hb in 6 M guanidine hydrochloride (2.3 S) is significantly larger than that of unirradiated Hb (1.3 S), which supports the above conclusion that stable cross‐links are generated in the photoreaction. The bonds formed are presumably not disulfides, since they resist cleavage by dithiothreitol. The rate of cross‐linking is diminished by N3, histidine, and bilirubin, but enhanced by D2O, indicating that 1O2 plays a role in the reaction. Cross‐linking is minimal when photooxidation is carried out at pH 6.0. but increases steadily with pH up to 9.0, suggesting that the reaction involves residues which titrate over this pH range.
RAPID RESPONSES TO LIGHT AND GIBBERELLIC ACID IN ETIOLATED PEA STEMS
Authors: Naunović Gordana , Nešković Mirjana
Published: January 2008

Abstract— An angular position sensing transducer has been used to investigate the effect of light and gibberellins on rapid growth responses in decapitated, dark‐grown pea stems. The immediate effect of 3 min of red (657 nm) light was a decrease in growth rate. Short wavelength far red light (728 nm) did not reverse the effect of red. Long wavelength far red (742 nm) reversed the inhibition only during the first 30 min. Gibberellic acid induced a rapid, transient increase in growth rate in dark‐grown and in red‐light‐irradiated plants. The length of the latent period in response to GA, was shorter in irradiated plants
COMPLEX FORMATION BETWEEN PYRENE AND THE NUCLEOTIDES GMP, CMP, TMP AND AMP
Authors: Lianos P. , Georghiou S.
Published: January 2008

Abstract—

Pyrene has been found to form ground and excited electronic state complexes of 1:1 stoichi‐ometry with GMP, CMP, TMP and AMP. The values of their ground state association constants are 45 M‐1, 13M‐1, 14 M‐1, and 52 M‐1 respectively. The fluorescence of pyrene is strongly quenched by GMP, CMP, and TMP but only slightly by AMP. Fluorescence quenching analysis has yielded the values 87M‐1, 73 M‐1, and 154 M‐1 for the excited state association constants with GMP, CMP, and TMP, respectively. The corresponding values for the excited state second‐order rate constant for complex formation are: 3.3 times 109M‐1 s‐1 4.1 times 109M‐1 s‐1, and 4.0 times 109M‐1 s‐1. The probabilities of complex formation per collision between an excited pyrene molecule and a nucleotide are: 0.52, 0.64, and 0.63. The values for the excited state rate constant for dissociation of the complex are: 3.8 times 107s‐1 5.6 times 107s‐1, and 2.6 times 107s‐1. The possibility is discussed that partial transfer of charge from pyrene to nucleotide may be playing a role in the complex formation process.
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.
PHOTOOXYGENATION OF MAGNESIUM meso‐TETRAPHENYLPORPHYRIN*
Authors: Matsuura Teruo , Inoue Kenzo , Ranade A. C. , Saito Isao
Published: January 2008

Abstract— On unsensitized photooxygenation magnesium meso‐tetraphenylporphyrin underwent oxidative ring cleavage yielding a bilitriene derivative as the sole product. Kinetic studies by quenching technique using singlet‐oxygen quenchers, ß‐carotene and α‐tocopherol, and by substrate direct disappearance technique (Foote and Ching) indicated that only singlet‐oxygen process is involved in the photooxygenation, and that the rate of total consumption of singlet oxygen (kQ+kR) is 1.0 ± 0.4 times 108M‐1s‐1.
EXCITED STATES OF DNA AND ITS COMPONENTS AT ROOM TEMPERATURE—IV. SPECTRAL, POLARIZATION AND QUANTUM YIELD STUDIES OF EMISSIONS FROM CpC AND POLY rC
Authors: Morgan James P. , Daniels Malcolm
Published: January 2008

Abstract— Corrected normalized emission spectra are reported for poly rC, CpC and CMP in neutral aqueous solution at room temperature. The emissions from CpC and poly rC show progressive and extensive depolarization across the emission band compared with CMP. Self‐consistent analysis of the polarization and spectral data allows the resolution of red‐shifted component emissions from the overall spectra and the evaluation of component polarizations. By comparison with experimental reference spectra three long wavelength components are identified in the poly rC emission and assigned as excimer fluorescence, monomer phosphorescence and excimer phosphorescence, whereas for CpC only two components are observed. The quantum yields are interpreted quantitatively in terms of the known stacking behavior of CpC and poly rC. with excimer emissions originating from the stacked fraction. Quantitative differences between CpC and poly rC are due to their different hypochromism and degree of stacking. Differences of polarization of excimer fluorescence are a consequence of different stacking geometries, and the directional properties of the transition moment suggest the excimer fluorescence is largely charge‐resonance in nature. The behavior of the CpC/poly rC system is compared with ApA/ poly rA.
THE PHOTODYNAMIC EFFECT OF HEMATOPORPHYRIN ON DNA
Authors: Boye Erik , Moan Johan
Published: January 2008

Abstract— Breakage of DNA in vitro and inside E. colt cells has been determined after exposure to monochromatic 365 nm light in the presence of 10 µM hematoporphyrin. When measured by alkaline sucrose sedimentation, the yields of breaks were 1.4 × 10‐12 per dalton and per J/m2 for Col El‐DNA in vitro and 5.9 × 10‐3 per dalton and per J/m2 for superinfecting phage Λ DNA inside E. coli cells made permeable by toluene. No breaks were found by neutral sucrose sedimentation, demonstrating that the lesions represent alkali‐labile bonds. The majority of the alkali‐labile bonds were induced by singlet oxygen, as evidenced by the several‐fold higher yield obtained in D2O‐containing buffer.
EXCITED STATES OF BILIRUBIN
Authors: Sloper R. W. , Truscott T. G.
Published: January 2008

Abstract— The excited states of bilirubin (BR) in a variety of environments have been studied by 347 nm laser flash photolysis. Quantum yields of formation of triplet BR have been shown to be less than 0.005 in solution in water (pH 9–11), methanolic ammonia, 10% aqueous mulgofen and in cetyl trimethyl‐ammonium bromide. In benzene the quantum yield was 0.01 although this diminished to less than 0.005 on addition of triethylamine. Permanent products are formed with benzene and with 1% methanolic ammonia. With BR in HSA a transient decaying with k = 3.5 × 105 s‐1 is formed by a monophotonic process together with a permanent product. Neither species is affected by oxygen or by iodide ion. Both originate from BR molecules in the strongest binding site in the HSA. The yields of both species are unaffected by salt but are temperature dependent. The decay of the transient is strongly temperature dependent corresponding to an activation energy of about 50–60 kj mol‐1. If this transient is a triplet it is formed with a quantum yield of 0.13 ± 0.01. The relevance of these results to an understanding of the photo therapeutic process is discussed.
THE DEPENDENCE OF THE QUANTUM YIELD OF LIGAND PHOTODISSOCIATION FROM HAEM PROTEINS ON ULTRAFAST RECOMBINATION
Authors: Duddell D. A. , Morris R. J. , Muttucumaru N. J. , Richards J. T.
Published: January 2008

Abstract— Measurements of relative photolysis yields in nanosecond flash photolysis studies of carbon monoxide and dioxygen complexes of haemoglobin and myoglobin are compared with published values of the quantum efficiency for photodissociation obtained from microsecond flash or continuous photolysis studies. It is shown that the differences in quantum yield between HbCO and MbCO and between Hb02 and Mb02 can be correlated with the different extent of ultrafast recombination observed in the nanosecond experiments. Furthermore, the temperature dependence of the quantum yield in the case of HbCO can be entirely attributed to the effect of temperature on the ultrafast recombination.
ON THE NATURE OF THE INTERMEDIATE ELECTRON ACCEPTOR (A1) IN THE PHOTOSYSTEM I REACTION CENTER
Authors: Baltimore Barbara G. , Malkin Richard
Published: January 2008

Abstract— A sodium dodecyl sulfate‐Photosystem I (PSI) complex has been prepared and characterized with respect to its electron acceptors. Component X and iron‐sulfur centers A and B are absent from this preparation but the intermediate electron acceptor (A1) is present. Flash‐induced absorbance changes at 25°C show charge separation, followed by a back‐reaction with a half‐time of 5 µs. The spectrum of the flash‐induced change from 350 to 550 nm indicates a contribution from the intermediate electron acceptor, A1, as well as from P700+. EPR studies show that A1 is associated with a free‐radical signal having a g‐value of 2.0025 and a linewidth of 12 gauss. A, would appear to be associated with a monomeric form of either Chi α or pheophytin a.
ABNORMAL EMBRYONIC DEVELOPMENT OF THE AMERICAN SEA URCHIN FOLLOWING ILLUMINATION OF GAMETES WITH VISIBLE LIGHT FROM A PHOTOTHERAPY UNIT
Authors: Speck William T. , Behrman Amy J. , Rosenkranz Pnina G. , Gordon Doria , Rosenkranz Herbert S.
Published: January 2008

Abstract— The unfertilized oocytes and spermatozoa of the American sea urchin (Arbacia punctulata) were exposed to phototherapy lights in order to determine the effect of this treatment regimen on post‐irradiation fertilization and embryonic development. Light treatment revealed dose‐dependent abnormalities in fertilization and subsequent embryonic development.
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.
PHOTOLYSIS OF IODODEOXYCYTIDINE IN DNA AND RELATED POLYNUCLEOTIDES: WAVELENGTH DEPENDENCE AND ENERGY TRANSFER*
Authors: Rahn R. O. , Sellin H. G.
Published: January 2008

Abstract— 5'‐Iodocytosine (IC) containing denatured DNA and poly(C) were prepared and the photoinduced loss of iodine measured for irradiation at wavelengths between 240 and 313 nm. The following intrinsic quantum yields (ΦINT) were obtained for irradiation at λex > 300 nm where only IC absorbs: denatured DNA (0.01), poly(C) (0.013), apurinic acid (0.018) and IdCMP (0.026). These results suggest that geometrical or structural restraints in the polymer, which increase with the degree of base stacking, inhibit the loss of iodine from an excited IC residue. The variation in the photochemical cross section for iodine photolysis was measured as a function of the wavelength of irradiation and found to vary in a manner which indicates that absorption by noniodinated residues can lead to iodine photolysis. It is proposed that energy transfer from neighboring bases to an adjacent IC residue takes place, resulting in an action spectrum for iodine photolysis which reflects absorption of excitation energy by noniodinated as well as iodinated residues. The contribution due to energy transfer in denatured DNA was estimated to be from not more than a single base located on either side of an IC residue. The degree of transfer was slightly less in iodinated poly(C) and decreased 4‐fold following depurination of the DNA. These results are consistent with a structurally dependent energy transfer process in which IC, because of its lower lying singlet state, can act as an energy trap.
THE 1‐CYANONAPHTHALENE EXCIMER IN HOMOGENEOUS AND MICELLAR SOLUTIONS
Authors: Turro Nicholas J. , Lee Plato C. C.
Published: January 2008

Abstract— An excimer of 1‐cyanonaphthalene is produced in homogeneous organic solvents and in micelle containing detergent solutions. From solvent effects in homogeneous solution it is concluded that the excimer is relatively polar (dipole moment ∼ 4D). From a comparison with emission from that observed in homogeneous solvents, it is concluded that 1‐cyanonaphthalene is solubilized mainly in the Stern Layer of sodium dodecyl sulfate (SDS) and hexadecyltrimethyl ammonium bromide (HDTBr) micelles. The influence of variation of detergent concentration on the excimer to monomer emission ratio and the influence of NaCl concentration on the excimer to monomer emission ratio have been determined. Excimer formation is shown to be a convenient method for determination of the Kraft point of SDS solutions.
PHOTOINACTIVATION OF CHINESE HAMSTER CELLS BY HEMATOPORPHYRIN DERIVATIVE AND RED LIGHT
Authors: Gomer Charles J. , Smith David M.
Published: January 2008

Abstract— The use of hematoporphyrin derivative (HpD) has previously been demonstrated to be beneficial in clinical cancer therapy. This paper describes cell culture studies used to examine HpD phototherapy in Chinese hamster ovary cells (line CHO). Survival curves have been obtained for both direct HpD toxicity and HpD induced photoinactivation. Examination of HpD induced photoinactivation as a function of stage in the cell growth cycle has also been performed, as has the quantitative measurement of HpD uptake in cells (using 3H‐HpD) as a function of cellular incubation time, serum concentration in the incubation medium, and cell cycle position. In the absence of light, no toxicity was observed for HpD incubation levels of up to 400 μg/m/ when incubations times were 3 h or less. Exposure of cells to light alone (> 590 nm, 4.0 mW/cm2) for 9 min was also found to be completely nontoxic. Survival curves obtained for exponentially growing cells labeled with various concentrations of HpD and subsequently illuminated with red light exhibited a threshold or shoulder region at short exposure times followed by exponential killing at longer exposure times. The cell cycle response curves for HpD induced photoinactivation of synchronized CHO cells was nearly flat, indicating no variation in sensitivity for cells treated at time periods from 6 to 15 h after mitosis. Additon of serum to the incubation medium resulted in improved plating efficiency and reproducible survival curves but decreased cellular uptake of HpD.
MIDDLE ULTRAVIOLET RADIATION REACHING THE OCEAN SURFACE*
Authors: Baker Karen S. , Smith Raymond C. , Green A. E. S.
Published: January 2008

Abstract— Direct measurements of the downwelling spectral irradiance in the middle UV (280–340 nm) have been made for a range of solar zenith angles (20°‐70°). These measurements were made for a marine atmosphere at equatorial latitudes. We fit these data to two semi‐empirical analytic representations, from which quantitative calculations of spectral irradiance in the middle UV incident at the ocean surface can be made. The formulae accommodate variation in wavelength, solar zenith angle, ozone thickness, aerosol thickness and surface albedo. Our purpose is to provide marine photobiologists and photochemists with a basis for estimating middle UV radiation levels reaching the ocean surface and the approximate changes caused by manmade alterations of the ozone layer.
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.
THE FORMATION OF TWO FORMS OF BATHORHODOPSIN AND THEIR OPTICAL PROPERTIES
Authors: Sasaki Norihiro , Tokunaga Fumio , Yoshizawa Toru
Published: January 2008

Abstract— Using two kinds of rhodopsin preparations (digitonin extract and rod outer segments suspension), we measured changes in absorption spectra during the conversion of rhodopsin or isorhodopsin to a photosteady state mixture composed of rhodopsin, isorhodopsin and bathorhodopsin by irradiation with blue light (437 nm) at 77 K and during the reversion of bathorhodopsin to a mixture of rhodopsin and isorhodopsin by irradiation with red light (> 650 nm) at 77 K. The reaction kinetics could be expressed with only one exponential in the former case and with two exponentials in the latter case. These data suggest that both rhodopsin and isorhodopsin are composed of a single molecular species, while bathorhodopsin is composed of two molecular species, designated as bathorhodopsin1 and bathorhodopsin2. The absorption spectra of these bathorhodopsin were calculated by two different methods (kinetic method and warming‐cooling method). The former was based on the kinetics of the conversion of two forms of bathorhodopsin by irradiation with the red light. The spectra obtained by this method were consistent with those obtained by the warming‐cooling method. Bathorhodopsin1 and bathorhodopsin2 have Λmax at 555 and 538 nm, respectively. The two forms of bathorhodopsin are interconvertible in the light, but not in the dark. Thus, we suggest that a rhodopsin molecule in the excited state relaxes to either bathorhodopsin1 or bathorhodopsin2 through one of the two parallel pathways.
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.
EFFECTS OF EXTRACELLULAR Ca2+ CONCENTRATION AND PAPAVERINE ON THE VISUAL CELL FUNCTION IN THE ISOLATED FROG RETINA
Authors: Hanawa Isao , Matsuura Tetsuji
Published: January 2008

Abstract— Effects of extracellular Ca2+ concentration and papaverine on the PIII response of the electroretinogram and the dark adaptation process of the visual cells were studied in the isolated, aspartate‐treated bullfrog retina. The amplitudes of both the fast and slow PIII responses are increased in 0.01 mM Ca2+ solution, but decreased in Ca2+‐free solution containing 1 mM EDTA. The application of 0.1 mM papaverine in the presence of 1 mM Ca2+ led to the enhancement of the slow PIII response at lower stimulus intensity and the prolongation of the slow PIII response, but these effects of papaverine on the response were lost when Ca2+ was removed from the bathing fluid. The half‐time of recovery of the fast PIII response amplitude after switching off the adapting light was a linear function of the amount of bleached rhodopsin. Papaverine in the absence of Ca2+ produced about 2‐fold increase in the half‐time of recovery of the response. These findings suggest that chemical reactions which are sensitive to papaverine in the absence of Ca2+ are implicated in the dark adaptation process of the visual cells.
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.
INHIBITION OF DNA REPAIR AND PRODUCTION OF SINGLE‐STRAND BREAKS IN ESCHERICHIA COLI BY REDUCTONE
Authors: Leitão A. C. , Caldas L. R. , Gomes R. Alcantara
Published: January 2008

Abstract— Reductone (HOCH2COCHO), a keto‐aldehyde produced by thermal degradation of some sugars, at alkaline pHs, blocks the excision repair of DNA lesions in uv‐irradiated wild type Escherichia coli. This probably occurs as a result of inhibition of the exonucleolytic activity of DNA polymerase I. In addition, reductone alone induces DNA single‐strand breaks. Repair of this damage is mainly dependent on the polA gene products.
THE EFFECTS OF PHOTOOXIDATION BY PROFLAVINE ON HeLa CELLS—II. DAMAGE TO DNA
Authors: Roberts Joan E.
Published: January 2008

Abstract— HeLa cell suspensions, prelabeled with specific [14C]‐nucleosides, were treated with proflavine and irradiated with visible light (400–500 nm). The DNA was isolated from the cells (as well as from the appropriate control cells) and examined for macromolecular and molecular changes. Although the UV absorbance spectrum of DNA from irradiated HeLa cells showed no discernible change, a fluorescence spectrum (excitation/emission: 305/405) indicated a molecular change in the DNA. Isolated DNA samples were hydrolyzed with 90% formic acid and chromatographed. There were no detectable differences between the irradiated and non‐irradiated profile (Rf and radioactivity) for both guanine and adenine. However, the chromatograms of thymine and cytosine showed distinct changes. There was a loss of radioactivity in the [14C]‐thymidine labeled samples, while the [14C]‐cytidine labeled samples indicated the formation of a new compound, containing 10% of the radioactivity, running just ahead of cytosine. These data strongly suggest the formation of a new compound resulting from the photooxidation of cytosine when nuclear DNA was sensitized by proflavine.
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.
UV‐ENHANCED REACTIVATION IN MAMMALIAN CELLS: INCREASE BY CAFFEINE
Authors: Lytle C. D. , Iacangelo A. L. , Lin C. H. , Goddard J. G.
Published: January 2008

Abstract— It has been reported that caffeine decreases UV‐enhanced reactivation of UV‐irradiated Herpes simplex virus in CV‐1 monkey kidney cells. That occurred when there was no delay between cell irradiation and virus infection. In the present study, virus infection was delayed following cell irradiation to allow an ‘induction’period separate from the ‘expression’period which occurs during the virus infection. Thus, the effects of caffeine on ‘induction’and ‘expression’could be determined separately. Caffeine increased the expression of UV‐enhanced reactivation, while causing a small decrease in the ‘induction’of enhanced reactivation.
ACTION SPECTRUM FOR PHOTOREACTIVATION OF ESCHERICHIA COLI Bs‐1 AFTER γ‐IRRADIATION
Authors: Skvortzov V. G. , Myasnik M. N. , Sokolov V. A. , Morozov I. I.
Published: January 2008

Abstract Measurements were performed to determine the action spectrum and dose dependence for photoreactivation of E. coli Bs‐1 cells after γ‐irradiation. The similarities between photoreactivation after UV‐ and after γ‐irradiation in action spectra, kinetics, and other characteristics indicate that the increased survival of γ‐irradiated cells after illumination with photoreactivating light is the result of true photoenzymatic repair.
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

–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 follows

where [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.
FLUORESCENCE OF 1‐DIMETHYLAMINONAPHTHALENE‐5‐SULFONATE AND PYRENE‐1‐SULFONATE CONJUGATED TO BACTERIORHODOPSIN
Authors: Nakabayashi Mikio , Mihashi Koshin
Published: January 2008

Abstract— Two fluorescence probes, 1‐dimethylaminonaphthalene‐5‐sulfonylchloride and pyrene‐1‐sulfonylchloride, were conjugated to the protein in purple membrane and fluorescence intensity and anisotropy were measured as a function of temperature. The anisotropy of the 1‐dimethyl‐aminonaphthalene‐5‐sulfonate conjugate showed a characteristic temperature dependence, in which, the anisotropy is constant at 0.22 ± 0.01 until 25‐30°C and decreases above 30°C. The fluorescence intensity, however, varies linearly with temperature. These results imply that the transition is due to bacteriorhodopsin in the trimer.
THE ‘OPSIN SHIFT’ IN BACTERIORHODOPSIN: STUDIES WITH ARTIFICIAL BACTERIORHODOPSINS
Authors: Balogh‐Nair Valeria , Carriker John D. , Honig Barry , Kamat Vinayak , Motto Michael G. , Nakanishi Koji , Sen Ranjan , Sheves Mordechai , Tanis Maria Arnaboldi , Tsujimoto Kazuo
Published: January 2008

Abstract— The difference (in cm−1) in absorption maxima between the protonated Schiff base of retinals and the pigment derived therefrom has been defined as the opsin shift. It represents the influence of the opsin binding site on the chromophore. The analysis of the opsin shifts of a series of dihydrobacteriorhodopsins has led to the external point‐charge model, which in addition to a counter anion near the Schiff base ammonium, carries another negative charge in the vicinity of the β‐ionone ring. This is in striking contrast to the external point‐charge model proposed earlier for the bovine visual pigment. The absorption maxima of rhodopsins formed from bromo‐ and phenyl retinals support the two models. A retinal carrying a photoaffinity label has yielded a nonbleachable bacteriorhodopsin.
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.
PHOTOEFFECTS OF VISIBLE AND ULTRAVIOLET RADIATION ON THE TWO‐SPOTTED SPIDER MITE, TETRANYCHUS URTICAE
Authors: Barcelo Jeanne A.
Published: January 2008

Abstract— The ability of the two‐spotted spider mite, Tetranychus urticae Koch, to detect and avoid various wavelengths was examined. The mites were given a choice between two regions: an area on a leaf exposed to light of defined spectral composition or an area protected from certain selected wavelength components. The mites showed little avoidance of visible, UV‐A or UV‐C wavelengths. In contrast, the animals strongly avoided the UV‐B spectral region, indicating that this arthropod can discriminate and respond to the presence of UV‐B wavelengths. The adult mites did not appear to be killed by the amount of UV‐B they could receive on a sunny summer day in Kentucky (i.e. 20 SU). However, the egg laying capacity of the females was reduced in a linear fashion as dose increased. Thus, avoidance of high UV‐B regions on a leaf may contribute to the survival of the species in nature.
SELECTIVE INACTIVATION OF MICROSOMAL DRUG METABOLIZING PROTEINS BY VISIBLE LIGHT
Authors: Augusto Ohara , Packer Lester
Published: January 2008

Abstract— Rat liver microsomes treated with heterochromatic visible light (λ > 400 nm) and O2 showed a preferential inactivation of NADPH‐cytochrome P450 reductase and cytochrome P450, proteins involved in drug metabolism. Cytochrome P450 destruction correlates with lipid peroxidation; both are oxygen dependent and affected to the same extent by antioxidants and radical scavengers. Under anaerobic conditions. NADPH‐cytochrome P450 reductase is the only component which is inactivated; this is accompanied by FMN loss and activity can be restored by reconstitution.
PHOTOALLERGIC CONTACT DERMATITIS TO MUSK AMBRETTE: ACTION SPECTRA IN GUINEA PIGS AND MAN*
Authors: Giovinazzo Vincent J. , Ichikawa Hideyuki , Kochevar Irene E. , Armstrong Robert B. , Harber Leonard C.
Published: January 2008

Abstract— Positive photopatch tests to musk ambrette were elicited using narrow band radiation in two patients with photoallergic contact dermatitis to musk ambrette and in photosensitized guinea pigs. The most effective wavelength range in the two patients was between 334 and 394 nm. Control subjects did not respond to the same light doses either in the presence or absence of musk ambrette. One patient exhibited maximum sensitivity at 346 nm. The action spectrum in guinea pigs extended from 322 to 406 nm with maximum response at 322 nm. Below 322 nm, erythema was observed at the same or higher doses than those required for evoking a minimal erythema response in non‐sensitized animals. Morphologically and histologically the response below 322 nm appeared to be normal delayed erythema. No erythema was elicited by radiation between 322 and 430 nm in non‐photosensitized animals which had received musk ambrette.
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.
INVOLVEMENT OF NEAR‐UV‐INDUCED SYNTHESIS OF SEROTONIN IN PHOTOPROTECTION AND IN POTENTIATION OF FAR‐UV LETHALITY IN THE YEAST CANDIDA GUILLIERMONDII
Authors: Fraikin G. Y. , Strakhovskaya Marina G. , Rubin Leonid B.
Published: January 2008

Abstract— This paper considers mechanisms of near‐UV (334nm) induced photoprotection as well as potentiation of far‐UV (254 nm) lethality in Candida guilliermondii. Using exogenous precursors of serotonin, it appears that the above two mechanisms involve photoactivated synthesis of serotonin. It has been postulated that the serotonin effect could take place by binding to DNA.
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.
EFFECTS OF IONOPHORES AND RUTHENIUM RED ON THE PHOTOTAXIS OF STENTOR COERULEUS AS MEASURED BY SIMPLE DEVICES
Authors: Chang Taek‐Hyoun , Walker Edward B. , Song Pill‐Soon
Published: January 2008

Abstract— Two simple methods of phototaxis measurements have been applied to study the effects of ionophores on the negative phototactic response in Stentor coeruleus. The inhibitory effects of Ca2+‐ionophore (A23187), Ca2+‐blocking agent (Ruthenium Red), and K+ ‐ionophore (valinomycin) on photo‐taxis have been determined. Results suggest that the influx of Ca2+ plays a transducing role in the phototaxis of Stentor.
UV‐INDUCED REVERSION OF ADENOVIRUS 5ts2 INFECTING HUMAN CELLS
Authors: Day Rufus S. , Ziolkowski Chuck H. J.
Published: January 2008

Abstract— Among the progeny produced by UV‐irradiated adenovirus 5ts2 when infecting either A498 (human kidney tumor) or CRL1187 (normal human fibroblast) strains at 32° C were a certain number (UV–fluence dependent) of revertants able to grow at 39° C. Within experimental error, the induced reversion frequency was independent of whether or not the cells received UV (5 J/m2) 20 h prior to infection, indicating that induced error‐prone repair was not observed in these experiments.
QUENCHING OF SINGLET OXYGEN BY SENSITIZER IN DYE‐SENSITIZED PHOTOOXYGENATION*
Authors: Tanielian Charles , Golder Lucien
Published: January 2008

Abstract— A general method for the determination of the extent of the singlet oxygen (1O2) quenching by sensitizer in the dye‐sensitized photooxygenation of olefins is used in the case of rose bengal (RB) in methanol and oil‐soluble chlorophyll (M) in benzene with 2‐methyl‐2‐pentene and tetramethylethylene as acceptors. Unlike RB, M which contains only a low percentage of pure chlorophyll (Chi), quenches 1O2. It is shown that this very cheap mixture can be used for kinetic studies and that the chemical quenching of 1O2 by M is very weak with respect to the physical quenching. The upper limit for the rate constants of physical and chemical quenching of 1O2 by Chi is estimated.
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.
TRANSMITTANCE OF NONIONIZING RADIATION IN HUMAN TISSUES*
Authors: Wan San , Parrish John A. , Anderson R. Rox , Madden Michael
Published: January 2008

Abstract— Spectral transmittance of 400–865 nm radiation through various human structures, including the skull with scalp, the chest wall, abdominal wall and scrotum, is presented. There is essentially no visible light of wavelengths shorter than 500 nm transmitted through the chest or the abdominal wall. In contrast, 10−5–10−4 of blue light can reach the brain and testes. Transmittance of all tissues increases progressively with wavelength from 600 to 814nm. The maximal transmittances are 10−2–10−1 for skulls and scrota, and 10−3–10−2 for chest and abdominal walls. Tissue thickness, optical absorption and scattering are major influencing factors.
ULTRAVIOLET RADIATION INDUCED CHANGES IN MACROPHAGE ACTIVITY
Authors: Schuller Georgia B. , Hellman Kiki B.
Published: January 2008

Abstract— The effect of ultraviolet (UV) radiation on macrophage activity was examined. Thioglycollate‐stimulated peritoneal exudate cells were collected from adult C57BL/6 mice. Ninety‐five per cent of the cells adhering to plastic petri dishes were macrophages as determined by the presence of a non‐specific esterase. Adherent cells were exposed to UV radiation of 0.5‐13.2 J/m2. Viability and phagocytosis were measured at 0, 24, 48, 72 and 96 h after exposure. A statistically significant UV exposure‐dependent decrease in macrophage viability and phagocytic capacity was observed. Macrophage viability and phagocytosis also decreased as a function of time after exposure to UV radiation.