bluuebunny/crossref_metadata_2025 huggingface dataset:
WAVELENGTH DEPENDENCE AND DOSE‐RATE INDEPENDENCE OF UV RADIATION‐INDUCED IMMUNOLOGIC UNRESPONSIVENESS OF MICE TO A UV‐INDUCED FIBROSARCOMA
Authors: Fabo E. C. De , Kripke M. L.
Published: January 2008

Abstract—

Irradiation of BALB/c mice with FS40 sunlamps induces susceptibility to challenge with syngeneic UV‐induced fibrosarcomas that otherwise would be rejected immunologically. Plastic filters were used to remove various wavelengths from the radiation source to identify the active waveband. Wavelengths above 315 nm (those transmitted through a mylar filter) were ineffective in producing tumor susceptibility, even when the total amount of energy applied was the same as that emitted by the unfiltered FS40 sunlamps. Removal of wavelengths below 275 nm (with a polystyrene filter) did not reduce the activity of the radiation. Alteration of the dose‐rate of the radiation by as much as a factor of 10. by irradiating animals through neutral density filters, did not change the proportion of tumor‐susceptible mice, suggesting that there is reciprocity with regard to dose‐rate and time of UV exposure. Cell transfer studies were used to test whether similar immunologic mechanisms were responsible for the equal susceptibility to tumor challenge of mice given continuous UV exposure (one 12‐h treatment) or fractionated exposures (twelve 1‐h treatments). With both treatment regimens, tumor susceptibility could be transferred to X‐irradiated recipients with lymphoid cells, provided that sufficient time had elapsed after the single treatment.
THE FLAVIN SENSITISED PHOTOOXIDATION OF ASCORBIC ACID: A CONTINUOUS AND FLASH PHOTOLYSIS STUDY
Authors: Heelis P. F. , Parsons B. J. , Phillips G. O. , McKellar J. F.
Published: January 2008

Abstract—The mechanism of the photooxidation of ascorbic acid by flavin mononucleotide has been studied by steady state and flash photolysis techniques. The primary reaction consists of an electron abstraction from ascorbic acid by the flavin singlet and triplet states by a diffusional process and in the latter case also by the formation of a triplet flavin‐ascorbic acid complex. Under anaerobic conditions, the secondary reactions consist primarily of a radical recombination and a ‘dark’chemical back reaction, leading to the reformation of unchanged flavin and ascorbic acid. In the presence of oxygen, the ‘back reactions’are prevented, resulting in the efficient photooxidation of ascorbic acid.
SENSITIZATION OF THE PHOSPHORESCENCE OF INDOLE THROUGH INTRAMOLECULAR ENERGY TRANSFER FROM THE TRIPLET STATE OF COVALENTLY LINKED ACETOPHENONE IN RIGID MEDIA AT 77 K
Authors: Tamaki Takashi
Published: January 2008

Abstract— In an attempt to study the quenching of the triplet state of acetophenone by indole, we have prepared the compounds containing these chromophores intramolecularly. The emission measurements in rigid glasses at 77 K have indicated that the quenching of the triplet acetophenone is due to intramolecular triplet‐triplet energy transfer to the indole chromophore, resulting in the sensitization of the indole phosphorescence. The efficiency of the energy transfer has reached ca. 100% in ethanol glasses, while it has been suggested that in methylcyclohexane glasses, the indole chromophore except for 1‐methyl derivative is subjected to strong interaction with the acetophenone chromophore other than electronic energy transfer.
LUMINESCENCE STUDIES OF QUINIZARIN AND DAUNORUBICIN
Authors: Capps Rodger N. , Vala Martin
Published: January 2008

Abstract— The absorption and emission spectra of quinizarin (1,4‐dihydroxy‐anthraquinone) have been investigated in hydrocarbon and alcoholic solvents. Fluorescence spectra in 3 different Shpolskii matrices were recorded at 14 K. Vibrational analyses of these spectra revealed the presence of 3, 8, and 9 sites in octane, heptane, and hexane matrices, respectively. The fluorescence lifetime was found to be 6.5 ns in hexane and EPA. Fluorescence photoselection measurements in EPA (77 K) showed that the first 4 electronic transitions of quinizarin are polarized parallel, parallel, perpendicular, and parallel to the long molecular axis and can be assigned, in order of increasing energy, to 1B2, 1B2, 1A1 and 1B2 (ππ*)→1A1(C2v,) transitions, respectively. The fluorescent transition is assigned as 1B1 (ππ*)→1A1. The absence of phosphorescence is attributed to the intramolecular hydrogen bonding present which displaces the parent anthraquinone n→* states above the ππ* states, thereby rendering the intersystem crossing (S1‐T1) radiationless pathway inefficient.

Photoselection measurements on daunorubicin, a substituted quinizarin and known anticancer drug, revealed an absorption band polarization pattern identical to that of quinizarin. These results are in part at variance with assumptions used in previous work on the intercalation specificity of daunorubicin with DNA.
PHYTOCHROME DESTRUCTION IN DARK ‐ AND LIGHT‐GROWN AMARANTHUS CAUDATUS SEEDLINGS
Authors: Heim Brigitte , Jabben Merten , Schäfer Eberhard
Published: January 2008

Abstract— Slow destruction of the far‐red‐absorbing form of phytochrome (Pfr), which has been observed in light‐grown oat and maize, occurs in light‐ and dark‐grown Amaranthus, Pharbitis, and Brassica seedlings as well. Destruction of Pfr in these seedlings shows two phases: if a high level of Pfr is produced in dark‐grown seedlings, the destruction is fast in the beginning and then slows after a low Pfr level has been reached. Slow Pfr destruction is predominant in light‐grown tissue.
EFFECTS OF SOLAR AND ARTIFICIAL ULTRAVIOLET‐B RADIATION ON LARVAL NORTHERN ANCHOVY, ENGRAULIS MORDAX*
Authors: Hunter John R. , Kaupp Sandor E. , Taylor John H.
Published: January 2008

Abstract— Northern anchovy larvae were exposed to various amounts of both natural (global solar) and artificial (sunlamps filtered by cellulose triacetate) UV‐B energy over a 12‐day period. Dosage was determined on the basis of a weighting function for biological effectiveness. The action spectrum on which this biologically effective dose for anchovy mortality is based was developed using broad‐band spectroscopy. These experiments indicated that biologically adverse conditions exist near the sea surface. Larvae exposed in shallow containers to global solar UV for 12 days suffered significant UV mortality from February to October. Larvae surviving all solar and artificial UV doses were smaller than those not exposed to UV. [Lowest dosage = 398 J·m−2(bio.eff.).] Fifty percent of the larvae survived a cumulative dose of 605 J·m−2(bio.eff.), or 50 J·m−2·day−1(bio.eff). Dose reciprocity did not hold; when a similar cumulative dose was given in the first 4 days of 12, there were about one‐half as many survivors.

One meter below the sea surface the daily solar UV dose (corrected for average cloud cover) is equal to or greater than 50 J·m−2(bio.eff.) (33°N, 118°W), the daily equivalent of the LD50, for 7 months of the year (March to September) at moderate chlorophyll‐a concentrations (0.5 mg‐m−3). These data suggest that larvae in the sea may be subject to some UV‐B stress at present. Owing to their seasonality of spawning and vertical distribution, anchovy populations may not be gravely endangered by moderate degree of stratospheric ozone diminution.
THE ACTION SPECTRUM OF DAPHNIA MAGNA (CRUSTACEA) PHOTOTAXIS IN A SIMULATED NATURAL ENVIRONMENT
Authors: Buchanan Claire , Goldberg Bernard
Published: January 2008

Abstract— The action spectrum of phototaxis in Daphnia magna (Crustacea) was measured in a chamber which simulated a natural angular distribution of underwater light. A 17% step‐down in irradiance was used to stimulate the phototactic response at all wavelengths and irradiances tested. Peaks in the spectral response curves depended on the fluence rate to which the zooplankton were acclimated. The wavelength of maximum response (Zmax) shifted from yellow‐green at the highest acclimation fluence rate (5.1 × 10−2 Wm−2) to blue‐violet at moderate rates. At low acclimation fluence rates, the blue‐violet maximum was retained and another maximum developed in the red. At the lowest fluence rate (1.6 × 10−5 Wm−2), the blue‐violet and red maxima were lost and another maximum developed in the near ultraviolet. The action spectrum indicates the presence of three, and possibly four, photopigments with Zmax, at ∼405, 440, 570 and 690nm. The 440 and 690nm maxima may belong to the same photopigment; however, this was not tested. Changes in zooplankton swimming speed, caused either by large changes in irradiance or by mechanical stimuli, were accompanied by changes in the strength of the phototactic response to the −17% stimulus at any irradiance level for white and monochromatic light, and indicated the presence of a mechanism connecting swimming speed and photosensitivity.
A CONVENIENT PHOTOCHEMICAL METHOD FOR REDUCTION OF FERRIC HEMES
Authors: Ward Brian , Chang C. K.
Published: January 2008

Abstract— A method has been developed for the reduction of ferric porphyrins and hemoproteins using ketyl radicals generated from ketone photoreduction. This method is applicable to both aqueous and non‐aqueous systems and has several advantages over the dithionite reducing agent.
PHOTOCHEMICAL ESTIMATION OF OXYGEN SOLUBILITY
Authors: Monroe Bruce M.
Published: January 2008

Abstract— A photochemical technique for estimating the solubility of oxygen in a solvent has been developed and used to estimate the solubility of oxygen in chloroform. From a measurement of the change in rubrene concentration and rubrene fluorescence lifetime as a sealed rubrene solution is irradiated and from the fluorescence lifetime of rubrene in nitrogen, air and oxygen‐saturated solvent the oxygen solubility constant and rate constant for oxygen quenching of rubrene fluorescence can be measured. For chloroform these values are 9.8 mM/atm and 7.9 109M‐1 s‐1 respectively.
A STUDY OF THE KINETICS OF INCLUSION OF HALONAPHTHALENES WITH ß‐CYCLODEXTRIN VIA TIME CORRELATED PHOSPHORESCENCE
Authors: Turro Nicholas J. , Bolt John D. , Kuroda Yasuhisa , Tabushi Iwao
Published: January 2008

Abstract— The phosphorescence of 1‐bromonaphthalene and 1‐chloronaphthalene is readily observable in nitrogen purged aqueous solutions containing ß‐cyclodextrin. Addition of acetonitrile increases both the phosphorescence intensity and lifetime. The quenching of halonaphthalene phosphorescence in aqueous solution by nitrite is substantially inhibited upon addition of ß‐cyclodextrin, as a result of a guest‐host complex. The rate constants for formation and dissociation of the l‐bromonaphthalene/ß‐cyclodextrin complex are evaluated from an analysis of the dependence of phosphorescence lifetimes on nitrite concentration.
PHYTOCHROME INTERMEDIATES IN VIVO—IV. KINETICS OF PfrEMERGENCE*
Authors: Spruit C. J. P.
Published: January 2008

Abstract—Rate constants for the formation of Pfr, the far‐red‐absorbing form of phytochrome, from photochemical intermediates, have been measuredin vivoin a number of plants. Two first order processes were observed, the slowest of which has been studied in detail. In pea epicotyl hooks, the rate constants proved dependent on temperature as well as on composition of the gas phase. A transition point was observed at about—2°C. Above this temperature the Arrhenius activation energy is 61 ± 6 kJ/mol, below the transition temperature 200 + 17 kJ/mol. The data correspond to half lives of between 0.4 and 0.2 s in an atmosphere of oxygen at 20°C, depending upon the species of plant. In oxygen‐free atmospheres, the rates are between 1.7 and 1.9 times as fast. The data prove that, on the time scale relevant to the usual type of photomorphogenetic experiments, the occurrence of phytochrome intermediates generally can be neglected. Exceptions to this generality are formed by experiments involving continuous or very rapidly intermittent exposures to very high light intensities. Under these conditions the steady state fraction of Pfrmay be considerably lower than calculated from the spectroscopic data for the pigment and the light sources.
PROPERTIES OF THE CHLOROPLAST FILM ELECTRODE IMMOBILIZED ON AN SnO2‐COATED GLASS PLATE
Authors: Ochiai Hideo , Shibata Hitoshi , Sawa Yoshihiro , Katoh Takashi
Published: January 2008

Abstract— Type C chloroplasts were deposited on the surface of an SnO2 optically transparent electrode glass plate with polyvinyl alcohol plus bovine serum albumin as immobilizing supports. This electrode, on illumination of 250 J/m2 in an electrolyte solution, generated anodic photo current more than 150 nA per 10 μg chlorophyll/cm2 of the SnO2 glass plate at a potentiostatic condition of + 0.5 V against a saturated calomel electrode, and gave rise to an open circuit potential up to 300 mV. The photocurrent output was enhanced as high as 60‐fold under the short circuit condition by the addition of an artificial electron carrier, l‐methoxy‐5‐methylphenazinium methyl sulfate, to the electrolyte solution. With the electrode poised at +0.5 V against a saturated calomel electrode, the enhancement effect was exhibited as high as 13‐fold in the presence of 2,6‐dichlorophenol indophenol. A photocurrent spectrum coincides well with an absorption spectrum of the chloroplast film electrode. Effects of heat‐treatment, photosynthetic inhibitors, and electrolyte's pH on the magnitude of the photocurrent were studied in detail. Water molecule, a primary electron donor in the chloroplast photosystems, contributes to the large majority of photocurrent generation. A minor output was observed with the electrode coated with completely inactivated chloroplasts, probably due to the chlorophyll photosensitization.
PHYTOCHROME and THE DEVELOPMENT OF PHOTOPHOSPHORYLATION CAPACITY—AN APPRAISAL OF THE EXPERIMENTAL APPROACH*
Authors: Oelze‐Karow H. , Mohr H.
Published: January 2008

Abstract— Development of the capacity for photophosphorylation (= total capacity for light‐driven ATP formation) in the mustard (Sinapis alba L.) cotyledons is strongly influenced by a red light pulse pretreatment which operates through phytochrome. The present report deals with several objections raised against the in situ assay of the rate of photophosphorylation. Experimental evidence is given in support of the assumption that the linear increase of the ATP content of the cotyledons as measured over 1.5 min after the onset of saturating white light (370 Wm‐2) in fact represents the maximum rate of photophosphorylation (‘capacity’). Moreover, it is confirmed that control by phytochrome of the development of the photophosphorylation capacity and of the capacity for chlorophyll synthesis are unrelated phenomena. The failure of development of the capacity for photophosphorylation in isolated cotyledons from dark‐grown seedlings cannot be attributed to deficiencies of chlorophyll synthesis.

It is concluded that the photophosphorylation response is particularly useful to study the mechanism of phytochrome (Pfr) action in case of a response which involves a threshold reaction and an interorgan (hook→cotyledon) cooperation.
PHOTOREACTIVATION ASSOCIATED WITH CHROMOSOMAL ABNORMALITY IN SEA URCHIN EGGS FERTILIZED WITH ULTRAVIOLET‐IRRADIATED SPERM
Authors: Ejima Yosuke , Shiroya Tsugio
Published: January 2008

Abstract Chromosomal abnormality due to the ultraviolet (UV) irradiation of sperm and its modification by photoreactivation (PR) were studied in the sea urchin, Hemicentrotus pulcherrimus. When sperm was UV‐irradiated and allowed to fertilize unirradiated eggs, the effect of UV was manifested as an abnormal separation of chromosomes at the anaphase of the first mitosis. The frequency of abnormal anaphase increased with UV fluence. In the UV fluence of larger than 20J/m2, more than 90% of eggs showed chromosomal abnormality. The UV‐induced chromosomal abnormality was prevented by photoreactivation when the fertilized eggs were illuminated with visible light. The PR sector for the PR of chromosomal abnormality, which was comparable to the PR sector for morphological abnormality, was higher than that of cleavage delay. The UV sensitivity expressed in terms of chromosomal abnormality was significantly higher than the sensitivity expressed in terms of morphological abnormality. Photo‐reactivation illumination sufficed to effect a nearly complete PR when applied up to 20 min after fertilization, while the PR effectiveness declined thereafter. Illumination after 40 min had little effect for PR.
ENZYMATIC GENERATION OF TRIPLET BIACETYL
Authors: Soares CarlosH. L. , H. Bechara EtelvinoJ.
Published: January 2008

Abstract The horseradish peroxidase‐catalyzed aerobic oxidation of 3‐methylacetoacetone yields biacetyl, partly in the electronically excited triplet state. This is indicated by the chemiluminescence spectrum, which corresponds to the phosphorescence spectrum of biacetyl, by the time course of the chemiluminescence emission which accompanies oxygen depletion, and by quenching studies with the sorbate ion.
NATURE OF THE INTERACTION BETWEEN THE PHOTOACTIVE COMPOUND PHENYLHEPTATRIYNE AND ANIMAL VIRUSES
Authors: Hudson J. B. , Graham E. A. , Towers G. H. N.
Published: January 2008

AbstractThe mechanism of action of the phototoxic polyacetylene phenylheptatriyne (PHT) against viruses was investigated. For this purpose the membrane containing mouse cytomegalovirus (MCMV) was treated with PHT in long wave UV light, and several functions of the virus were then examined. Following this treatment MCMV retained its structural integrity, as revealed by electron microscopy, resistance to exogenous deoxyribonuclease, and sedimentation‐velocity. The treated virus was also normal in its ability to penetrate into the nuclei of susceptible mouse cells. Replication of the virus was defective, however, in that infectious centers could not be established and no infectious progeny resulted. Two RNA‐containing viruses, Sindbis and infectious hematopoietic necrosis virus (IHNV, a fish virus), both of which contain membranes, were inactivated by PHT in long wave UV as efficiently as MCMV. In contrast, the fish virus IPNV (infectious pancreatic necrosis virus), which does not possess a membrane, was resistant to PHT. Thus, it appears that PHT, in the presence of long wave UV, exerts its action via the viral membrane and as a consequence the viral genome, DNA or RNA, is unable to replicate.
PHOTOINACTIVATION OF SPINACH NITRATE REDUCTASE SENSITIZED BY FLAVIN MONONUCLEOTIDE. EVIDENCE FOR THE INVOLVEMENT OF SINGLET OXYGEN
Authors: Vargas M. A. , Mauriño S. G. , Maldonado J. M. , Aparicio P. J.
Published: January 2008

AbstractAll the activities of the nitrate reductase complex from spinach are irreversibly inactivated by irradiation of the enzyme with blue light in the presence of flavin mononucleotide. The photoinactivation requires oxygen and is prevented by ethylenediaminetetraacetic acid and by reduced nicotinamide adenine dinucleotide, but not by superoxide dismutasepluscatalase. On the other hand, the inactivation is markedly enhanced in 77% deuterated water and it is suppressed by the singlet oxygen quenchers azide, histidine and tryptophan. All these results suggest that singlet oxygen generated by light absorption by flavin mononucleotide, rather than excited flavin mononucleotide or other oxygen species, is the primary agent involved in the photooxidative inactivation of the enzyme.
POSTREPLICATION REPAIR IN uvrA AND uvrB STRAINS OF ESCHERICHIA COLI K‐12 IS INHIBITED BY RICH GROWTH MEDIUM
Authors: Sharma Rakesh C. , Barfknecht Thomas R. , Smith Kendric C.
Published: January 2008

Abstract Escherichia coli K‐12 uvrA or uvrB strains grown to logarithmic phase in minimal medium showed higher survival after ultraviolet (UV) irradiation (254 nm) if plated on minimal medium (MM) instead of rich medium. This‘minimal medium recovery’(MMR) was largely blocked by additional recA56 (92% inhibition) or lexA101 (77%) mutations, was partially blocked by additional recB21 (54%), uvrD3 (31%) or recF143 (22%) mutations, but additional polA1 or polA5 mutations had no effect on MMR. When incubated in MM after UV irradiation, the uvrB5 and uvrB5uvrD3 strains showed essentially complete repair of DNA daughter‐strand gaps (DSG) produced after UV radiation fluences up to ∼ 6 J/m2 and ∼1 J/m2, respectively, and then they accumulated unrepaired DSG as a linear function of UV radiation fluence. However, when they were incubated in rich growth medium after UV irradiation, they did not show the complete repair of DSG and unrepaired DSG accumulated as a linear function of UV radiation fluence. The fluence‐dependent correlation observed for the uvrB and uvrB uvrD cells between UV radiation‐induced killing and the accumulation of unrepaired DSG, indicates that the molecular basis of MMR is the partial inhibition of postreplication repair by rich growth medium. Rich growth medium can be just MM plus Casamino Acids or the 13 pure amino acids therein in order to have an adverse effect on survival, regardless of whether the cells were grown in rich medium or not before UV irradiation.
ULTRAVIOLET LIGHT: PHOTOSENSITIVITY AND OTHER EFFECTS ON THE VISUAL SYSTEM *
Authors: Stark William S. , Tan Karel E. W. P.
Published: January 2008

Abstract It is generally stated in elementary lectures on sensory systems that the limits of the visible spectrum are 400 nm (violet) and 700 nm (red), although there are several exceptions to this generalization. Recently, the properties of ultraviolet (UV) vision in invertebrates, as well as vertebrates, have been better characterized, and it is worthwhile to examine visual phenomena in the UV region of the spectrum. The purpose of this review is to integrate what is known about UV vision in invertebrates, which have been particularly well studied, with a growing literature on UV sensitivity and UV effects in the visual systems of humans and other vertebrates.
UV‐ACTION SPECTRUM (254‐405 nm) FOR INHIBITION OF A K+ ‐STIMULATED ADENOSINE TRIPHOSPHATASE FROM THE PLASMA MEMBRANE OF ROSA DAMASCENA
Authors: Imbrie Catherine W. , Murphy Terence M.
Published: January 2008

A K +‐stimulated ATPase from suspension‐cultured rose cells was isolated and subjected to UV radiation. The characteristics of the ATPase resembled those of a plasma‐membrane associated enzyme and not those of the mitochondrial enzyme. The ATPase required Mg2+ and was further stimulated up to 100% by K+. K+ stimulation was specific for ATP. The order of stimulation by monovalent cations was K+ > Na+ > Li+. The enzyme had a pH optimum of 6.5 in the presence of 50 mM K+. It was almost completely inhibited by diethylstilbestrol and partially inhibited by vanadate. but was not affected by azide or oligomycin. The inhibition of ATPase activity by various fluences of UV indicated that one fraction of the K+‐stimulated activity was very sensitive to radiation, while another fraction was relatively insensitive. It is possible that UV distinguished between two enzymes. The action spectra for inhibition of both fractions showed maxima at 290 nm and significant but much lower action throughout the near‐UV region, resembling spectra in the literature for the inhibition of transport processes in bacteria.
THE ELECTROCHEMICAL PROTON GRADIENT IN THE PHOTOSYNTHETIC PURPLE SULPHUR BACTERIUMCHROMATIUM VINOSUM
Authors: Davidson Victor L. , Knaff David B.
Published: January 2008

Cells of the photosynthetic purple bacteriumChromatium vinosumgenerate a transmembrane electrochemical proton gradient (δμH+H+) on illumination. The steady state values of the two components of δμH+m+, δpH and the membrane potential (δψ) have been measured as a function of both the pH and ion composition of the external medium. While δψ and δpH vary considerably as the external pH is varied from 5.5 to 7.5, the magnitude of δμH+h+remains relatively constant over this pH range. δψ is relatively unaffected by the ion composition of the medium but δpH and δμH+H+both vary considerably depending upon the cation present in the medium. The use of specific ionophores to eliminate either δpH or δψ results in changes in the magnitude of the other component. The δpH values determined here were used to predict the direction of Tl+flux via the potassium‐proton antiport and to demonstrate the reversibility of this antiport.
PHOTOPEROXIDATION OF LENS LIPIDS: PREVENTION BY VITAMIN E
Authors: Varma Shambhu D. , Beachy Natalie A. , Richards Richard D.
Published: January 2008

Abstract— Light of visible frequency was observed to initiate peroxidative degradation of lipids of rat lenses when the latter were maintained in organ culture. The extent of degradation was monitored by measurement of malanaldehyde. This photodegradative process, which we believe is triggered by light catalyzed generation of superoxide and its subsequent transformation to other potent oxidants. was observed to be thwarted substantially if the medium of organ culture was fortified with 10−3 and 107M vitamin E (α‐tochopherol). These studies suggest that vitamin E may be metabolically beneficial by protecting light exposed tissues, such as those in the eye against photoperoxidativc damage concomitant to light‐catalyzed generation of oxygen‐free radicals. The findings appear relevant to age‐associated pathogenesisof cataracts and their possible attenuation. In addition, they provide a basis of pathogenesis in other ocular tissues such as the macula known to undergo age‐dependent degeneration.
EFFECT OF INACTIVATION OF THE OXYGEN‐EVOLVING SYSTEM ON THE THERMOLUMINESCENCE OF ISOLATED CHLOROPLASTS
Authors: Rózsa Zsuzsa , Demeter Sándor
Published: January 2008

Abstract— The effect of inactivation of water‐splitting enzyme on the thermoluminescence of isolated chloroplasts was investigated. The inhibitory treatments used included Tris‐washing, alkaline pH in the presence of the uncoupler gramicidin, incubation with a high concentration of magnesium ions and different chaotropic agents. It was found that inhibition of oxygen evolution resulted in the disappearance of the main thermoluminescence band at +20°C. The A band which appears at — 10°C and has been related to the S4 state of the water‐splitting enzyme (Inoue, 1981) was not considerably affected by the inhibition of oxygen evolution. The results presented here indicate that the participation of the S4 state of water‐splitting enzyme in the generation of the A band should be reinvestigated.
INFLUENCE OF PHOTON FLUX DENSITY IN THE 400–700 nm WAVEBAND ON INHIBITION OF PHOTOSYNTHESIS BY UV‐B (280–320 nm) IRRADIATION IN SOYBEAN LEAVES: SEPARATION OF INDIRECT AND IMMEDIATE EFFECTS
Authors: Warner Charles W. , Caldwell Martyn M.
Published: January 2008

Abstract— Visible radiation can substantially influence the degree to which plant photosynthesis is inhibited by UV‐B radiation. This study was designed to separate the immediate effects of visible radiation on UV‐B photosynthetic inhibition from the indirect influence of visible irradiation on morphological and physiological properties of leaves during leaf development. Soybean plants were pretreated in growth chambers with either high or low visible irradiance (750 and 70 μmol m‐2s‐1 quantum flux in the 400–700 nm waveband, respectively) during the development of leaves used subsequently for UV irradiation. Test leaves still attached to the plant were exposed to 5 h of polychromatic UV‐B irradiation and the photosynthetic capacity (net CO2 exchange) was determined before and after the UV irradiation. During the UV irradiation, plants from both pretreatment groups received either high or low visible flux. Development of leaves in the high visible flux pretreatment conditions resulted in thicker leaves, higher chlorophyll a/b ratios, more UV‐absorbing pigments, and reduced sensitivity to the UV‐B irradiation. However, higher visible flux during the UV‐B irradiation resulted in greater depression of photosynthesis by the UV‐B irradiation. The relative magnitude of photosynthetic depression under these treatment combinations was the same when photosynthesis was measured under either light‐limited or light‐saturated conditions.
IRREVERSIBLE PHOTO IN ACTIVATION OF NITRATE REDUCTASE DURING THE FLAVIN‐SENSITIZED PHOTOCHEMICAL ASSAY OF ITS CATALYTIC ACTIVITY
Authors: Rosa Miguel A. Dela , Rosa Francisco F. Dela
Published: January 2008

Abstract—The classic photochemical system in which flavin and EDTA act as photosensitizer and electron donor, respectively, has been employed for assayingin vitrothe catalytic activity ofAnkistrodesmus brauniinitrate reductase. When the photochemical assay is performed under air, but not in anaerobiosis, a considerable decay in the nitrite photoproduction rate is observed after 10–15 min. which is accompanied by a decrease of reduced methyl viologen‐nitrate reductase activity. The first enzyme activity, i.e. diaphorase is photoinactivated even more quickly and does not present any initial lag phase. Some oxygen species (superoxide and/or hydrogen peroxide) are probably involved in the photoinactivating mechanism, which appears to be non‐specific and irreversible.

The use of flavin/EDTA photosystems is therefore, very practical for thein vitroassay of nitrate reductase activity, although anaerobic conditions are required for optimum results. Since inactivation of the terminal activity is, however, relatively slow, anaerobiosis would not be required for assay times shorter than 10 min.
CHLOROPHYLLb: AN INTEGRAL COMPONENT OF PHOTOSYSTEM I OF HIGHER PLANT CHLOROPLASTS
Authors: Anderson Jan M. , Brown Jeanette S. , Lam Eric , Malkin Richard
Published: January 2008

Abstract—An undissociated photosystem I complex may be isolated from spinach thylakoids by mild gel electrophoresis (CP1a) or Triton X‐100. CP1a has a Chla/bratio of 11 and a Chl/P700 ratio of 120. while the Triton X‐100 PS I complex (Chla/bratio of 5.9) has a larger antenna unit size (Chl/P700 ratio of 180). None of the Chla/b‐proteins of the main light‐harvesting complex (apoproteins of 30–27 kD) are present in CP1a, and they account for less than 10% of the total chlorophyll in the Triton X‐100 PS I complex. Instead, these PS I complexes have specific, but as yet little characterized, Chia/b‐proteins (apoproteins in the 26–21 kD range). With both PS I complexes, Chibtransfers light excitation to the 735 nm low temperature fluorescence band characteristic of photosystem I. We suggest that Chibis an integral but minor component of photosystem I.
CATALYTIC ACTION AND DESTRUCTION OF PROTOHEMATIN DURING PEROXIDE DEPENDENT LUMINOL CHEMILUMINESCENCE
Authors: Olsson T. , Ewetz L. , Thore A.
Published: January 2008

Abstract— The catalytic action of protohematin was studied during the H2O2‐dependent chemiluminescent luminol reaction. In spite of the fact that the catalyst was ultimately inactivated, the average protohematin molecule catalyzed the consumption of about 103 molecules of luminol. The inactivation of catalyst and the initial consumption of luminol were studied during the luminescent reaction with different concentrations of reactants. A scheme accounting for the experimental observations is proposed. The formation of a primary protohematin‐H2O2 complex is followed by binding of luminol, resulting in a ternary complex. A nucleophilic attack by a second molecule of H2O2 on the luminol molecule results in light emission from excited aminophthalate via a hypothetical peroxide adduct. The destruction of protohematin occurs via the attack of H2O2 on the porphyrin structure of the protohematin‐H2O2 complex. Second order rate constants for the destruction of protohematin, the formation of the luminol complex and the nucleophilic attack of H2O2 are presented.
PHOTOINDUCTION OF PROTOPERITHECIA IN NEUROSPORA CRASSA BY BLUE LIGHT
Authors: Innocenti F. Degli , Pohl U. , Russo V. E. A.
Published: January 2008

Blue light induces the formation of Neurospora crassa protoperithecia.This photoinduction is completed in less than 24 h. Its threshold is about 4.2 J/m2. Red light is ineffective. The Bunsen‐Roscoe law is obeyed at the fluence of 12.6 J/m2 for fluence rates from 5.25 × 10 2 to 1.05 W/m2.
REMARKABLE INHIBITION OF OXYGEN QUENCHING OF PHOSPHORESCENCE BY COMPLEXATION WITH CYCLODEXTRINS
Authors: Turro Nicholas J. , Cox G. Sidney , Li Xin
Published: January 2008

The phosphorescence of the 4‐bromo‐l‐naphthoyl group is readily quenched by molecular oxygen in homogeneous solvents. However, when this lumophore is complexed with γ‐cyclodextrin in aqueous solution at room temperature, its phosphorescence is observed even under 1 atm of oxygen! Phosphorescence decay data indicated that two types of probe/cyclodcxtrin complexes are formed with lifetimes of 600 u,s and 3.5 ms. Oxygen completely quenches the fast decay, but only partially quenches the slow decay.
PHOTOPRODUCTS OF CHLORPROMAZINE WHICH CAUSE RED BLOOD CELL LYSIS
Authors: Kochevar Irene E. , Hom Jennie
Published: January 2008

A mechanism for chlorpromazine (CPZ) phototoxicity has been proposed that attributes the response to formation of stable, toxic photoproducts which cause cell membrane disruption. We have characterized these toxic photoproducts as dimers and higher multimers of CPZ. Chlorpromazine solutions (3 or 10 mA/) were irradiated with a medium pressure Hg lamp filtered to exclude λ < 280 nm. Five low mol wt photoproducts were separated by high performance liquid chromatography. Two were identified as CPZ‐sulfoxide and promazine. Higher mol wt photoproducts were separated by Sephadex G‐50 chromatography into 3 broad bands which were characterized by their absorption and fluorescence spectra. Band A (mol wt > 800) had λmaxabs= 263 nm, λmaxfl= 490 nm and Band B (mol wt = 350‐800) had λmaxabs= 255 nm, λmaxfl= 450 nm. Based on the mol wt of CPZ, Band A contained trimers and higher mol wt compounds and Band B was composed of dimeric structures. BandC(λmaxabs= 255,310 nm; λmaxfl= 445 nm) was composed of CPZ (mol wt = 315) and the low mol wt photoproducts. Red blood cell lysis was used as an assay for the ability of photoproducts to cause membrane disruption. Bands A and B, but not Band C, caused cell lysis. These data indicate that the CPZ photoproducts which cause cell membrane disruption are dimers (Band B) and higher multimers (Band A).
PICOSECOND LASER PHOTOLYSIS STUDIES OF FLUORESCENCE QUENCHING MECHANISMS OF FLAVIN: A DIRECT OBSERVATION OF INDOLE‐FLAVIN SINGLET CHARGE TRANSFER STATE FORMATION IN SOLUTIONS and FLAVOENZYMES
Authors: Karen Akiya , Ikeda Noriaki , Mataga Noboru , Tanaka Fumio
Published: January 2008

Formation of singlet charge transfer (heteroexcimer) states in the course of the fluorescence quenching of lumiflavin and riboflavin tetrabutyrate by indole and N‐methylindole have been directly observed by means of time‐resolved absorption spectral measurements using a picosecond laser photolysis method. Similar transient spectra have been observed also in the case of a flavoenzyme, D‐amino acid oxidase.
HALORHODOPSIN and PHOTOSENSORY BEHAVIOR INHalobacterium halobiumMUTANT STRAIN L‐33
Authors: Traulich Bernhard , Hildebrand Eilo , Schimz Angelika , Wagner Gottfried , Lanyi Janos K.
Published: January 2008

Halobacterium halobium, strain L‐33, which is deficient in bacteriorhodopsin (BR) but synthesizes increased amounts of halorhodopsin (HR), shows behavioral responses upon changes in fluence rate with visible light or with UV light. The observations support the earlier report (Schimzet al., 1982). that BR is not essential for photosensing inH. halobium.In the UV‐range, changes in light intensity elicit the maximal response at λ= 370 nm. In the visible range, changes in light intensity show the maximal response at Δ= 565 nm and a secondary peak at Δ= 590 nm. The latter corresponds to the absorption maximum of HR (Δmax= 588 nm). This light‐energy converting retinal pigment ofH. halobiumthus appears to contribute to photosensory behavior.
COMPARISON OF ACTION SPECTRA FOR ACUTE CUTANEOUS RESPONSES TO ULTRAVIOLET RADIATION: MAN and ALBINO HAIRLESS MOUSE*
Authors: Cole C. A. , Davies R. E. , Forbes P. D. , D'Aloisio L. C.
Published: January 2008

Abstract The hairless mouse has been used as an experimental model for photocarcinogenesis for about 20 years. Although the carcinogenesis action spectra for mice and man are not known, acute responses to ultraviolet radiation (UVR) in the biologically active UVB and UVC region (wavelengths below 320 nm) can be compared. Vascular response (predominantly edema) action spectra for monochromatic radiation in the Skh:HR‐l (albino hairless) male mouse were determined. These action spectra were found to be very similar to the human erythema action spectrum that had been developed using the same monochromator. The accuracy of this experimentally derived action spectrum was tested with a series of polychromatic source spectra. The mice were exposed to radiation from a long arc Xe lamp filtered by varying thicknesses of Schott WG320 filters, which yielded a wide range of biologically effective spectra. Spectral irradiance measurements, when weighted with the mouse edema and human erythema action spectra and multiplied by the irradiation time required to elicit a threshold response (edema), yielded a constant weighted dose regardless of irradiation spectral quality. The integrated effective dose was approximately 200 J/m2 of 297 nm equivalent energy, agreeing with requirements for the monochromatic 297 nm dose in the mice as well as for minimal human erythema. These data suggest a commonality in the UVR chromophores of mice and men as they relate to the acute responses described, and a direct additivity of effectiveness from the UVR components in a polychromatic beam, at least over the portion of the UVR spectrum tested (λ > 295 nm).
PHOTODYNAMIC INACTIVATION OF R3230AC MAMMARY CARCINOMAIN VITROWITH HEMATOPORPHYRIN DERIVATIVE: EFFECTS OF DOSE, TIME, and SERUM ON UPTAKE and PHOTOTOXICITY
Authors: Hilf Russell , Leakey Pauline Bo , Sollott Steven J. , Gibson Scott L.
Published: January 2008

AbstractPrimary cultures of the R3230AC mammary adenocarcinoma were used for pharmacokinetic studies of hematoporphyrin derivative (HPD), a preparation containing several porphyrin species and useful as a photoactivatable anti‐tumor agent. Uptake of HPDin vitrowas shown to be time‐, dose‐ and temperature‐dependent with an apparent plateau reached at 2 ‐ 4 h. An increase in the amount of serum in the medium progressively reduced the amount of HPD taken up by the cells; at a level of 10% serum, uptake of HPD was reduced by >95%. The time‐course of efflux of HPD from these cells demonstrated a complex pattern, with an initial rapid component followed by a more gradual rate of efflux up to 4 h. Assessment of photoradiation‐induced cytotoxicity was performed by a method developed to quantitatively measure trypan blue exclusion. Relative cytotoxicity was determined by use of heat‐killed cells as a standard. At two different concentrations of HPD, cytotoxicity was dependent on light exposure time. The presence of serum, which reduced uptake of HPD was correctable to reduced cytotoxicity. Based on the amount of light exposure to produce 50% cell kill, an order of potency was obtained for HPD > hematoporphyrin > hydroxyethylvinyldeuteroporphyrinin vitro.This order of potency correlated with the relative proportion of hydrophobic components as estimated by HPLC analysis. The results indicate that HPD is an effective cytotoxic agentin vitroin a well‐differentiated mammary adenocarcinoma model.
ACTINOMETRY IN MONOCHROMATIC FLASH PHOTOLYSIS: THE EXTINCTION COEFFICIENT OF TRIPLET BENZOPHENONE AND QUANTUM YIELD OF TRIPLET ZINC TETRAPHENYL PORPHYRIN
Authors: Hurley John K. , Sinai Naomi , Linschitz Henry
Published: January 2008

Abstract— The extinction coefficient εT, of triplet benzophenone in benzene has been directly determined by absolute measurements of absorbed energy and triplet absorbance, ΔD0T, under demonstrably linear conditions where incident excitation energy, E0, and ground state absorbance, A0, are both extrapolated to zero. The result, 7220 ± 320 M‐1 cm‐1 at 530 nm, validates and slightly corrects many measurements relative to benzophenone of triplet extinction coefficients made by the energy transfer technique, and of triplet yields obtained by the comparative method.

As E0 and A0 both decrease, ΔD0T becomes proportional to their product. In this situation, the ratio R= (1/A0)(dΔD0T/dE0) = (εT ‐ εG)φT. Measurements of R, referred to benzophenone, give (εT ‐ εG)φT for any substance, without necessity for absolute energy calibration.

Both absolute and relative laser flash measurements on zinc tetraphenyl porphyrin (εT ‐ εG at 470 nm = 7.3 × 104M‐1 cm‐1) give φT= 0.83 ± 0.04.
INDUCTION OF DNA STRAND BREAKS IN NORMAL HUMAN FIBROBLASTS EXPOSED TO MONOCHROMATIC ULTRAVIOLET AND VISIBLE WAVELENGTHS IN THE 240–546 nm RANGE
Authors: Rosenstein Barry S. , Ducore Jonathan M.
Published: January 2008

Abstract— The induction of DNA single‐strand breaks in normal human fibroblasts exposed to monochromatic wavelengths from 240–546 nm was measured by the alkaline elution assay. The cells were irradiated at 1°C to prevent both repair of induced breaks and formation of enzymatically induced breaks through excision repair. The cultures were also washed with and irradiated while suspended in phosphate buffered saline to prevent the formation of DNA damaging photoproducts from medium components. The action spectrum for DNA strand breakage was found to exhibit one peak at 265 nm, consistent with DNA absorption, and a second peak at 450 nm. The normalized action spectrum in the visible is similar to the normalized absorption spectrum for riboflavin, a known photosensitizing agent, implicating this molecule as the absorbing chromophore.
PERMEATION OF LYSOSOMAL MEMBRANES IN THE COURSE OF PHOTOSENSITIZATION WITH METHYLENE BLUE AND HEMATOPORPHYRIN: STUDY BY CELLULAR MICROSPECTROFLUOROMETRY
Authors: Santus R. , Kohen C. , Kohen E. , Reyftmann J. P. , Morliere P. , Dubertret L. , Tocci P. M.
Published: January 2008

Abstract—The photodynamically‐induced liberation of lysosomal enzymes using ß‐galactosidase as marker for the lysosomal enzymes has been studied by microspectrofluorometry on mouse L cells. Similar studies have been carried out using N‐acetyl‐ß‐D‐glucosaminidase as marker for the lysosomal enzymes of human fibroblasts. The high sensitivity of the fluorescence detection makes it possible to use 4‐methylumbelliferyl substrates for the enzymes contained in a single cell. Methylene blue and hematoporphyrin readily incorporate into both cells and upon excitation, sensitize lysosomal membrane damages, leading to enzyme release accompanying strong morphological changes.
AN ULTRASENSITIVE BIOASSAY FOR THE DETECTION OF FUROCOUMARINS AND OTHER PHOTOSENSITIZING MOLECULES
Authors: Ashwood‐Smith M. J. , Poulton G. A. , Ceska O. , Liu M. , Furniss E.
Published: January 2008

Abstract—A photobiological assay based upon inhibition of growth in the DNA repair‐deficient bacteriumE. coli Bs‐1, is described for the analysis of a number of photosensitizing agents. The lower limits of detection were as follows: psoralen 5 × 10‐11g; 5‐methoxypsoralen 1 × 10‐9g; 8‐methoxypsoralen 1 × 10‐9g; 4,5',8‐trimethylpsoralen 1 × 10‐11g; angelicin 5 × 10‐9g; 5,7‐di‐methoxycoumarin 1 × 10‐7g; isoimperatorin 5 × 10‐9g; dictamnine 1 × 10‐8g; oxypeucedanin 5 × 10‐7g; 5‐nitroxanthotoxin 5 × 10‐7g; and α‐terthienyl 1 × 10‐6g. All active compounds with the exception of α‐terthienyl were more easily detected by several orders of magnitude byE. coli Bs‐1than with the normal wild typeE. coli.5—Geranoxypsoralen and isopimpinellin were not active. The application of this technique, after TLC, to the analysis of complex mixtures from lemon oil, oil of bergamot,Heracleum lanatum, Angelica dawsonii, and celery and parsnip is illustrated. The bioassay described is more rapid and sensitive than previously published methods, permits replica plates to be made, and allows tentative identification of the photosensitized molecular target.
OXYGEN DEPENDENCY OF PHOTOCYTOTOXICITY WITH HAEMATOPORPHYRIN DERIVATIVE
Authors: See K. Lee , Forbes I. J. , Betts W. H.
Published: January 2008

Abstract— Exposure of Raji cells to haematoporphyrin derivative (HPD) and red light caused marked cytotoxicity. This was completely inhibited under anaerobic conditions. By using sodium dithionite in aqueous solutions, precise and graded oxygen concentrations could be achieved. Cytotoxicity was directly proportional to the oxygen concentration of the medium until a maximum was reached at a pO2 of 90 mm Hg. Sodium dithionite did not affect the viability of test cells and did not alter the chromatographic profile of HPD. Dithionite did not interfere with the uptake of HPD by cells. Dependency of phototoxicity upon aerobic conditions suggests that the cytotoxic agent is derived from oxygen and is consistent with the hypothesis that singlet oxygen and/or oxygen‐derived free radicals play an important role in photochemotherapy with HPD.
CHEMILUMINESCENCE INDUCED BY OXIDATION OF TRYPTOPHAN BY SINGLET OXYGEN AND BY HYPOCHLOROUS ACID. IMPLICATIONS IN THE LUMINESCENCE EMITTED IN PHAGOCYTOSIS
Authors: Violet P. Fornier de , Veyret B. , Vincendeau P. , Caristan A.
Published: January 2008

Abstract— The mechanism of the chemiluminescence emitted during phagocytosis of opsonized zymosan was investigated. The use of an artificial system generating singlet oxygen permitted the distinction between the respective roles of O2 and HOCl in the light production via the reactions with opsonized zymosan, amino‐acids and peptides. The reaction of free hypochlorous acid, produced by the myeloperoxidase H2 O2‐Cl‐ system, with free tryptophan appears to be a likely path for the production of chemiluminescence. Implications for the mechanism of in vivo chemiluminescence during phagocytosis are considered.
BINDING OF HEMATOPORPHYRIN DERIVATIVE TO HUMAN SERUM ALBUMIN
Authors: Grossweiner Leonard I. , Goyal Greesh C.
Published: January 2008

AbstractDialysis of hematoporphyrin derivative fraction A (HpD‐A) off human serum albumin at 38°C followed the Hill equation for cooperative binding with saturation at 5 to 8. 600 dalton porphyrin units. Approximately 15% of the HpD‐A was free for concentrations typical of human serum in photoradiation therapy. Possible structures of the tumor‐localizing and ‐photosensitizing component in HpD‐A are considered. Of these, a folded‐over, covalent dimer appears to be more consistent with the photophvsical properties.
PORPHYRIN ACCUMULATION BY ATHEROMATOUS PLAQUES OF THE AORTA
Authors: Kessel David , Sykes Elizabeth
Published: January 2008

AbstractA complex mixture of porphyrins termed hematoporphyrin derivative (HPD) has been clinically useful for tumor localization. When sections of human aorta containing atheromatous plaques were incubated with HPD, accumulation of fluorescent porphyrin was observed within the plaques. Analytic studies showed that the plaques had accumulated hematoporphyrin (HP), which is substantially more hydrophilic than that HPD fraction generally associated with tumor localization. Fluorescence spectra suggest that the plaque binding sites of HP resemble the relatively aqueous micelles formed by the detergent sodium dodecylsulfate. This result has implications for tumor‐localization procedures, since accumulation of hydrophilic porphyrins by tumors has been reported.
SKIN OPTICS AND PHOTOTHERAPY OF JAUNDICE
Authors: Pratesi Riccardo , Ronchi Laura , Cecchei Giovanna , Sbrana Giuseppe , Migliorini Maria Grazia , Vecchi Corrado , Donzelli Gianpaolo
Published: January 2008

Abstract The Kubelka–Munk theory of radiation transfer is applied to determine the influence of skin optical losses on the efficiency of phototherapy of jaundice. Using a multi‐layer model of the skin the photon absorption rate of bilirubin molecules is calculated for spectrally Gaussian light sources and fluorescent lamps used in phototherapy. Light absorption and scattering processes in the skin layers shift the optimum value of the peak excitation wavelength from λ= 453 nm (absorption maximum of bilirubin in vitro) to λ= 480 nm. This suggests the clinical investigation of narrow‐spectrum lamps emitting in the blue‐green region of the spectrum.