bluuebunny/crossref_metadata_2025 huggingface dataset:
SURVIVAL AND PYRIMIDINE DIMERS IN CULTURED FISH CELLS EXPOSED TO CONCURRENT SUN LAMP ULTRAVIOLET AND PHOTOREACTIVATING RADIATIONS
Authors: SHIMA AKIHIRO , SETLOW R. B.
Published: January 2008

Abstract— Cultured fishcells(RBCF–1 line) were irradiated with filtered sun lamp ultraviolet (SL‐UV; > 280 nm) together with or followed by illumination with daylight(DL) radiation (> 350 nm). The colony forming ability of the cells decreased with increasing fluence of SL‐UV. Concurrent exposure of cells to SL‐UV and DL, however, increased survival relative to exposure to SL‐UV alone. The photoreactivable fraction reached 0.52 at22–25‡C. By using a constant fluence modification factor of 86, the shape of dose‐survival curve was found to be almost the same for 254 nm and SL‐UV. In parallel with photoreactivation of cell survival, changes in the numbers of pyrimidine dimers in permeabilized cell DNA and in extracted total DNA were determined by measurements of endonuclease‐sensitive sites (ESS). The yield of ESS in both DNA's increased almost linearly with increasing SL‐UV fluence, although the yield in extracted DNA was about double of that in permeabilized cell DNA. The yield of ESS per unit fluence by 254 nm was about 70‐fold greater than SL‐UV. The fraction of cells inactivated per ESS was almost the same for 254 UV and SL‐UV. In SL‐UV‐irradiated cells, the photoreactivable fractions in terms of ESS were ‡ 10% higher in extracted DNA than in the DNA of permeabilized cells and also were higher when DL was administered separately after SL‐UV‐irradiation. When irradiated cells were exposed to DL at 0‡C, the photoreactivable fractions of both DNAs were appreciably less, indicating that the photoreactivation of ESS was enzymatic. These results support the suggestion that the mechanism for cell killing, mainly formation of pyrimidine dimers, by SL‐UV is the same as that by 254 UV.
LETHAL ACTION OF ULTRAVIOLET AND VISIBLE (BLUE‐VIOLET) RADIATIONS AT DEFINED WAVELENGTHS ON HUMAN LYMPHOBLASTOID CELLS: ACTION SPECTRA AND INTERACTION SITES
Authors: TYRRELL R. M. , WERFELLI P. , MORAER E. C.
Published: January 2008

Abstract— The repair proficient human lymphoblastoid line (TK6) has been employed to construcr an action spectrum for the lethal action of ultraviolet (UV) radiation in the range254–434 nm and to examine possible interactions between longer (334, 365 and 405 nm) and shorter wavelength (254 and 313 nm) radiations. The action spectrum follows a DNA absorption spectrum fairly closely out to 360 nm. As in previously determined lethal action spectra for procaryotic and eucaryotic cell populations, there is a broad shoulder in the334–405 nm region which could reflect the existence of either (a) a non‐DNA chromophore or (b) a unique photochemical reaction in the DNA over this region. Pre‐treatment with radiation at 334 or 365 nm causes either a slight sensitivity to (low fluences) or protection from (higher fluences) subsequent exposure to radiation at a shorter wavelength (254 or 313 nm). Pre‐irradiation at a visible wavelength (405 nm) at all fluence levels employed sensitizes the populations to treatment with 254 or 313 nm radiations. These interactions will influence the lethal outcome of cellular exposure to broad‐band radiation sources.
INVESTIGATIONS ON THE MECHANISM OF CHLORPROMAZINE PHOTOTOXICITY: EFFECTS ON LYSOSOMES OF CULTURED HUMAN FIBROBLASTS
Authors: Hasei Kazuyoshi , Ichihashi Masamitsu , Mojamdar Manoj
Published: January 2008

Abstract The effect of chlorpromazine (CPZ) and UVA on lysosomes of cultured normal human fibroblasts has been investigated. Acid phosphatase (ACPase) activity in 12 000 g pellet of cells treated with CPZ (10 μg/ml) and UVA (6 × 104 J/m2) was found to be decreased as compared with non‐treated, CPZ or UVA treated control cells. This decrease, however, was not accompanied by a concomitant increase in ACPase activity in the 12 000 g supernatant. The addition of Triton X‐100 to cells pretreated with CPZ + UVA resulted in only a moderate increase in ACPase activity of the 12 000 g supernatant. ACPase activity of the cells incubated in media containing preirradiated CPZ was also found to he decreased. These results indicate that CPZ + UVA directly inactivate lysosomal enzymes, possibly without affecting the membrane.
QUENCHING OF TRIPLET BENZOPHENONE BY VITAMINS E and C and BY SULFUR CONTAINING AMINO ACIDS and PEPTIDES
Authors: Encinas M. V. , Lissi E. A. , Olea A. F.
Published: January 2008

Abstract— The quenching rate of triplet benzophenone in water and/or water mixtures has been determined employing vitamin C, vitamin E, cystine, cysteine, reduced and oxidized glutathione, methionine and DL‐penicillamine. In these systems, the ketyl radical quantum yield and the benzophenone photoreduction yield have also been measured. The ketyl quantum yield is 1.0 in presence of vitamin C and smaller than 0.3 in presence of glutathione, cysteine and cystine. The data imply that quenching by thiols and disulfides takes place, at least in very polar solvents, mainly by a mechanism involving charge transfer intermediates.
PARTICIPATION OF THE TWO PHOTOSYSTEMS IN LIGHT DEPENDENT HYDROGEN EVOLUTION IN Scenedesmus obliquus
Authors: Randt Christoph , Senger Horst
Published: January 2008

Abstract— The H2‐photoproduction in the presence of dithionite measured in wild type and mutant cells of Scenedesmus obliquus demonstrates two sequential phases. In mutants showing only PS I activity phase 1 of H2‐photoproduction is visible with its core activity. When PS II is developed during greening, considerable activity is added to the core of phase I and phase II activity appears. Addition of DCMU reduces H2‐photoproduction by about 90%. The residual activity is completely attributed to the core of phase I. It was concluded that the core of phase I is dependent upon PS I only and can use sources different from water as electron donors. Phase II is dependent upon the capacity of PS II, a functioning photosynthetic apparatus and water as electron donor. The results are supported by studies of wavelength dependent activity of the two separate phases of H2‐photoproduction.
THERMOLUMINESCENCE and OXYGEN EVOLUTION FROM A THERMOPHILIC BLUE‐GREEN ALGA OBTAINED AFTER SINGLE‐TURNOVER LIGHT FLASHES*
Authors: Jee Govind , Koike H. , Inoue Y.
Published: January 2008

Abstract— Oxygen evolution and thermoluminescence (TL) studies on a thermophilic blue‐green alga Synechococcus vulcanus Copeland revealed the following: (a) The deactivations of the S3 and S2 states of the Oxygen Evolving Complex, at room temperature, have half‐times of ∼200 and 75 s, respectively, instead of 30 and 20 s found in mesophilic plants, (b) The TL band(s) “B”, due to the recombination of the state S2 or S3 and QB, the reduced secondary quinone acceptor, is(are) at50–55°C instead of25–30°C; the intensity of this band oscillates with a period of 4 with maxima on the 2nd and the 6th flashes, (c) The TL band “D” in the presence of diuron, due to the recombination of S2 and the reduced primary quinone acceptor QA,− occurs at ∼35°C instead of0–10°C. (d) Furthermore, the ratio of QB− to QB in dark‐adapted S. vulcanus cells is close to 1 as in intact spinach leaves, but not 0.43 as in isolated thylakoids from spinach.
THE EFFECTS OF AGGREGATION ON THE FLUORESCENCE and THE TRIPLET STATE YIELD OF HEMATOPORPHYRIN
Authors: Smith Gerald J.
Published: January 2008

Abstract— The fluorescence and triplet state yields of hematoporphyrin have been measured in wuter/methanol mixtures. There is a closely linked response of these yields to aggregation of the hematoporphyrin molecule. The monomer, which is the principal species present at high methanol content, has a triplet state yield of 0.91 and a fluorescence yield of 0.09. By contrast, hematoporphyrin solutions with a high water content containing aggregates have lower fluorescence and triplet state yields, e.g. 0.018 and 0.56, respectively, in water. Static, singlet state quenching in some of the aggregates is responsible for the reduced fluorescence yield. The results also show that in addition to these aggregates there are other types of aggregates where there is an increased singlet to ground state radiative transition probability, resulting from the interaction between transition dipoles in adjacent molecules.
SINGLE‐STRAND BREAKS IN SUPERCOILED DNA INDUCED BY VACUUM‐UV RADIATION IN AQUEOUS SOLUTION
Authors: Takakura Kaoru , Ishikawa Mitsuo , Hidea Kotaro , Kobayashi Katsumi , Ito Atsushi , Ito Takashi
Published: January 2008

We studied the induction of single‐strand breaks in the DNA of plasmid pBR 322 by vacuum‐UV radiation above 145 nm in aqueous solutions in relation to the production of OH‐radicals in water. The similarity and dissimilarity were examined of the wavelength dependence between the two effects. The maximum of single strand breaks at 150 nm could be explained by the action of OH‐radicals derived from direct water photolysis: the maximum at 180 nm remains unexplained. There was no indication that the direct absorption of photon by the DNA molecule plays an important role in the production of single‐strand breaks.
PHOTOHEMOLYSIS OF HUMAN ERYTHROCYTES LABELED IN BAND 3 WITH EOSIN‐ISOTHIOCYANATE
Authors: Pooler John P. , Girotti Albert W.
Published: January 2008

Eosin‐isothiocyanate (EYNCS) is 50 to 100 times more effective in sensitizing delayed photo‐hemolysis of human erythrocytes than is eosin when matched for absorbance in the reaction medium. These dyes are equally efficient in generating singlet oxygen, a potent membrane oxidant. When cells are treated with sensitizer and washed extensively prior to illumination, EYNCS phototoxicity persists, while that of eosin is lost. SDS‐gel electrophoresis of membranes from EYNCS‐exposed cells shows a large fluorescence signal coincident with band 3 protein that is abolished by pretreatment with H2DIDS, the inhibitor of anion exchange by band 3. This treatment reduces the photohemolytic potency of EYNCS by over 90%. The marked enhancement of photohemolytic activity upon binding sensitizer to band 3 implicates band 3 itself as a site of photodamage leading to lysis.
PHOTOIONIZATION OF TRYPTOPHAN: AN ELECTRON SPIN RESONANCE INVESTIGATION
Authors: Hoebeke M. , Gandin E. , Lion Y.
Published: January 2008

The photoionization of tryptophan has been studied by ESR spectroscopy using the free radical scavenger 5, 5 dimethyl‐1‐pyrroline‐l‐oxide as a spin trap for hydrated electrons. A special set‐up has been devised to irradiate more than one aliquot of the bubbled aqueous solutions in the cavity without removing the ESR cell out of the cavity.

Quantum yields of electrons production have been estimated as a function of irradiation wavelength. No photoionization threshold has been observed in these experiments.
WAVELENGTH DEPENDENCE FOR THE INDUCTION OF BACTERIOPHAGE LAMBDA BY ANTITUMOR AGENT GILVOCARCIN V
Authors: Elespuru Rosalie K. , Hitchins Victoria M.
Published: January 2008

The wavelength dependence for the induction of a lambda‐lacZ fusion phage of E. coli by photo‐activated gilvocarcin V was determined using a spot test or a quantitative assay for the lacZ gene product. Suspensions of bacteria and chemical were exposed to radiation of different wavelengths in the region 313‐546 nm, using a double grating monochromator. The prophage induction profiles generated were similar to the absorption spectrum of gilvocarcin V in this region, with a peak near 400 nm. The radiation fluence and chemical concentration required for threshold levels of prophage induction exhibited a nearly reciprocal relationship. These results have implications for the therapeutic use of gilvocarcins as antitumor agents.
THE PHOTOLYSIS OF TRYPTOPHAN WITH 337.1 nm LASER RADIATION
Authors: Borkman R. F. , Hibbard L. B. , Dillon James
Published: January 2008

Abstract— Aqueous solutions of L‐tryptophan were photolyzed by exposure to 337.1 nm radiation from a pulsed nitrogen laser. These data were compared with results for the 290 nm conventional‐source photolysis of tryptophan. The progress of photolysis was monitored by fluorescence analysis of tryptophan. UV absorption spectroscopy, HPLC, TLC, and proton NMR spectroscopy. The loss of Trp was observed to be first order for 290 nm photolysis but of mixed order for 337.1 nm photolysis. Five photolysis products were detected by TLC analysis, including: N‐formylkynurenine. kynurenine, tryptamine (detected after 290 nm photolysis but not 337.1 nm photolysis) and two unknown products. The tryptophan‐containing peptides N‐acetyl‐tryptophanamide (NATA) and tryptophylglycine (Trp‐Gly) were also observed to photolyze upon 337.1 nm laser radiation demonstrating that this phenomenon is not restricted to free tryptophan monomer.

Since Trp is not ordinarily thought to absorb U V radiation at wavelengths as long as 337.1 nm. a number of experiments were performed in an effort to determine the mechanism of photolysis at this wavelength. Evidence is presented which indicates that the 337.1 nm laser photolysis of Trp does not result from two photon absorption, dielectric breakdown, or other laser‐specific processes. Instead. it is concluded that this photolysis results either from a very weak absorption tail extending to 337.1 nm in tryptophan itself or from a reaction involving an impurity sensitizer which absorbs the 337.1 nm radiation. The sensitizing impurity. if present, could not. however, be removed by preparative HPLC and could not be detected by TLC or fluorescence analysis.
ENHANCED SUSCEPTIBILITY TO HPD‐SENSITIZED PHOTOTOXICITY AND CORRELATED RESISTANCE TO TRYPSIN DETACHMENT IN SV‐40 TRANSFORMED IMR‐90 CELLS
Authors: Denstman Steven C. , Dillehay Larry E. , Williams Jerry R.
Published: January 2008

Abstract— The response of a normal human cell strain, IMR‐90 and a line derived from it by SV40 transformation were compared after treatment in vitro with hematoporphyrin derivative (HPD) and red light. Transformed cells were inactivated at a significantly higher rate than normal cells when assayed by clonogenic survival. Co‐treatment with HPD and light also induces cellular resistance to enzymatic cleavage by trypsin; transformed cells exhibit a greater resistance than the normal cells to detachment from the growing surface. These data indicate that transformed cells may possess intrinsic characteristics that render them more sensitive than normal cells to HPD‐induced phototoxicity and that the plasma membrane may be the site of differential toxicity.
RNA—PROTEIN CROSSLINK AND RNA CHAIN BREAK FORMATION ON UV‐IRRADIATION OF TOBACCO MOSAIC VIRUS
Authors: Dobrov E. N. , Arbieva Z. H. , Khromov I. S. , Kust S. V.
Published: January 2008

Abstract— The ability of UV‐irradiation (254 nm) to induce formation of RNA‐protein crosslinks in tobacco mosaic virus (TMV) particles have been studied by Cs2SO4 density gradient centrifugation, analytical centrifugation, nitrocellulose filter binding and two‐dimensional peptide mapping. RNA‐protein crosslinks were found to be formed on UV‐irradiation of TMV, but the parallel process of UV‐induced RNA chain breakage complicated their quantitation. Using speciall devised equations, the quantum yield of RNA‐protein crosslink formation was found to be 0.65 × 10−5 and that of RNA chain break formation 0.95 × 10−5.
PYRIMIDINE DIMER FORMATION IN HUMAN SKIN
Authors: Freeman Steven E. , Gange Richard W. , Sutherland John C. , Sutherland Betsy M.
Published: January 2008

Cyclobutyl pyrimidine dimers are major photoproducts formed upon irradiation of DNA with ultraviolet light. We have developed a method for detecting as few as one pyrimidine dimer per million bases in about 50 ng of non‐radioactive DNA, and have used this method to quantitate dimer yields in human skin DNA exposed in situ to UV. We found that UVA radiation (320–400 nm) produces detectable levels of dimers in the DNA of human skin. We also measured UVB‐induced dimer yields in skin of individuals of differing sun sensitivity and found higher yields in individuals with higher UVB minimal erythema doses and greater sun sensitivity. These approaches should provide important information on damage induced in human skin upon exposure to natural or artificial sources of ultraviolet radiation.
PULSED RADIATION STUDIES OF PHOTODYNAMIC SENSITISERS: THE NATURE OF DHE
Authors: Keir W. F. , Land E. J. , MacLennan A. H. , McGarvey D. J. , Truscott T. G.
Published: January 2008

Abstract Laser flash photolysis has previously been used to study the nature of DHE via measurements of photophysical parameters which are dependent on the molecular weight of the system being studied. These results to date allow only a lower limit to be established for DHE which imply that in some environments such as detergents more than two porphyrin units are linked. We have now determined the triplet extinction coefficient of DHE by the pulse radiolysis technique via an energy transfer method which allows the triplet extinction of DHE to be estimated independent of the molecular weight. The combined techniques allow the actual molecular weight of DHE to be established at about 4200. Laser flash techniques have also now been used to determine, for a number of potential photodynamic sensitisers, the quantum yield of triplet state formation (θT) and, using the direct luminescence of singlet oxygen at 1270 nm, the quantum yield of singlet oxygen formation (θδ). For many of the porphyrins studied θδ is less than θT. For DHE itself there is a substantial increase in θδ in detergent compared to buffer. The θδ yields for a number of related systems including 'simple’systems such as haematoporphyrin, for linked porphyrin‐chlorin systems, (including DHE in which the end porphyrin is reduced to a chlorin–DHEC), and for phthalocyanines are compared. For the DHEC the θδ is close to that of DHE itself which may imply that such chlorins could be of use in photodynamic therapy (PDT).
OVERVIEW OF EXPERIENCES WITH PHOTODYNAMIC THERAPY FOR MALIGNANCY IN 192 PATIENTS
Authors: McCaughan James S.
Published: January 2008

Abstract From April 1982 to April 1986 we used photodynamic therapy to treat 192 patients with various malignancies. In all, 172 injections of hematoporphyrin derivative and 135 injections of dihematoporphyrin ether were made intravenously to sensitize the tumors; 684 photodynamic treatments were given using a tunable dye argon laser system for the light source. The technical problems of the light source and delivery systems are presented and the efficacy of therapy is analyzed.
SYNTHESIS AND PHOTOSENSITIZING ACTIVITY OF A DI‐PORPHYRIN ETHER
Authors: Pandey Ravindra K. , Dougherty Thomas J.
Published: January 2008

AbstractA simple, well characterized porphyrin dimer with ether linkage was synthesized from 2‐ (1‐hydroxyethyl)deuteroporphyrin dimethyl ester and found to be an effective in vivo photosensitizer in the murine SMT‐F tumor system. The structure of the pure dimer was confirmed by NMR and mass spectroscopy.
MEMBRANE DAMAGE AND RECOVERY ASSOCIATED WITH GROWTH DELAY INDUCED BY NEAR‐UV RADIATION IN Escherichia coliK–12
Authors: Pizarro Ramón A. , Orce Luis V.
Published: January 2008

Abstract— The growth delay induced by near‐UV radiation has been largely attributed to injured tRNA's and to the stringent response. We report an associated membrane perturbation whose recovery determines substantial modifications in the behavior of log phase Escherichia coliK–12 exposed to sublethal doses of near‐UV radiation (366 nm). When incubated at 37°C in plain nutrient broth, cells suffered a growth delay of about 100 min with parallel inhibition of several membrane functions. Conversely, when grown in conditions known to influence membrane activities, these were slightly inhibited and the growth delay lasted about 50 min. All the above conditions triggered the stringent response, characterized by an equivalent post‐irradiation burst of intracellular guanosine 5′3′ tetra and pentaphosphate and by a similar decay rate of the nucleotides accumulated at time 0 of the growth lag. According to our data the polyphosphates' half decay time in irradiated cells remains practically constant and close to 15 min. But, while cells from unsupplemented broth at 37°C resumed normal growth in around 100 min those with recovered membranes were rescued from growth inhibition in about one half of that time.
Phycornyces: TURGOR PRESSURE BEHAVIOR DURING THE LIGHT AND AVOIDANCE GROWTH RESPONSES
Authors: Ortega Joseph K. E. , Manica Keith J. , Keanini Russell G.
Published: January 2008

Abstract— The turgor pressure of the stage 4b sporangiophore of Phycomyces blakesleeanus was continuously measured with a pressure probe before and during a period of increased elongational growth rate elicited by a step‐up in blue light fiuence rate (a positive light growth response) or by a double‐barrier stimulus (avoidance growth response). In these and other experiments it was found that a step‐up in turgor pressure between 0.02 and 0.05 MPa may elicit an increase in growth rate that is comparable to those of the light and avoidance growth responses. The results of the present work demonstrate that the turgor pressure does not increase during these growth responses, indicating that the increased growth rate is solely the result of altered cell wall mechanical properties. Furthermore, very small decreases in turgor pressure could be detected during the period of increased growth rate. This turgor pressure depression is predicted by the Growth Equations, and provides further support for the conclusion that the light and avoidance growth responses are solely the result of changes in cell wall mechanical properties.
MOUSE SKIN PHOTOSENSITIVITY WITH DIHAEMATOPORPHYRIN ETHER (DHE) AND ALUMINIUM SULPHONATED PHTHALOCYANINE (AlSPc)
Authors: TRALAU C. J. , YOUNG A. R. , WALKER N. P. J. , VERNON D. I. , MACROBERT A. J. , BROWN S. B. , BOWN S. G.
Published: January 2008

Abstract Skin photosensitivity of sun exposed sites is the major side effect of dihaematoporphyrin ether (DHE) photodynamic therapy (PDT). Reports of severe oedema and erythema have generally been anecdotal. We have studied aluminium sulphonated phthalocyanine (AlSPc) as a potential photosensitiser for PDT. In this paper we report our work comparing the skin photosensitivity reactions of DHE and AlSPc. We have studied: (i) the time course of the skin reactions, (ii) the effect of increasing time from administration of photosensitiser to irradiation, (iii) drug‐skin reaction dose response. Groups of Skh I female hairless albino mice were given an intravenous bolus dose of either 0.9% saline solution, AlSPc or DHE (Photofrin II). Drug doses ranged from 0.5 to 50 mg/kg. At times ranging from 1 h to 1 month animals were irradiated with a range of doses of solar simulated radiation (SSR). The skin reaction was observed over a 2 week period. DHE reactions were always more severe than those with AlSPc. Peak skin reaction was seen at 3 h for DHE and 6 h for AlSPc. DHE reactions were still visible 2 weeks after irradiation whereas the AlSPc reaction disappeared by 48 h. Irradiation evoked a reaction up to 2 months after administration of DHE but only up to 2 weeks with AlSPc. The mean SSR dose at which a skin reaction was seen decreased with increasing dose of both agents. The rate of decrease was slower with AlSPc than DHE. This study suggests that in PDT, AlSPc will cause much less skin photosensitivity than DHE.
PHYTOCHROME IN GREEN‐TISSUE: PARTIAL PURIFICATION and CHARACTERIZATION OF THE 118‐KILODALTON PHYTOCHROME SPECIES FROM LIGHT‐GROWN Avena sativa L.*
Authors: Tokuhisa James G. , Quail Peter H.
Published: January 2008

Abstract—

The predominant, immunochemically‐detectable phytochrome polypeptide rapidly extracted directly into boiling sodium dodecyl sulfate‐containing buffer from fresh or freeze‐dried green Avena tissue has an apparent molecular mass of 118 kilodaltons (kDa). This result indicates that the 118‐kDa phytochrome species obtained from green Avena by extraction and rapid processing under non‐denaturing conditions in previous studies was not derived by partial proteolysis of a larger polypeptide present in the cell. Additional data do, however, demonstrate the presence in green tissue homogenates of proteolytic activity that can cause a = 6‐kDa reduction in apparent molecular mass and a blue‐shift in the Pfr absorbance maximum of phytochrome during handling. This proteolytic activity contrasts with that previously encountered in etiolated tissue in that it is not inhibited by phenylmethylsulfonyl fluoride, but is inhibited by iodoacetamide and leupeptin. This result indicates that the activity is associated with a thiol‐like protease.

A partial purification procedure that incorporates the use of iodacetamide and a novel chromatographic step is described for green‐tissue phytochrome. This procedure provides 50% recovery with a 90‐fold enrichment of phytochrome relative to the initial extract in which the chromoprotein is 0.003% of the total soluble protein. The final fraction is apparently free of proteolytic activity. Immunoblot analysis of this fraction demonstrates that the predominant immunoreactive band has a monomeric molecular mass of 118 kDa. Comigration of this band with a band exhibiting zinc‐induced fluorescence on blots of the partially purified preparations verifies that the 118‐kDa species is the principal tetrapyrrole‐bearing polypeptide present. Spectral properties of the final fraction are identical to those published for crude green‐tissue extracts, indicating the stability of the molecule's spectral properties throughout the procedure. Size exclusion chromatography under nondenaturing conditions shows that the 118‐kDa phytochrome species from green tissue comigrates with the dimeric, etiolated‐tissue molecule, and is therefore suggestive of similar quaternary structure. Together these data reinforce previous conclusions that the predominant phytochrome molecule present in the living cells of green tissue is resolvable as a 118‐kDa species, distinct from the well‐characterized 124‐kDa molecule from etiolated tissue (Tokuhisa et al., 1985, Planta 164, 321–332), and indicate that the partial purification protocol described here sustains the green‐tissue phytochrome in its native state throughout the procedure.
THE EPIDERMAL CELL KINETIC RESPONSE TO ULTRAVIOLET B IRRADIATION COMBINES REGENERATIVE PROLIFERATION AND CARCINOGEN ASSOCIATED CELL CYCLE DELAY
Authors: Olsen Wenche Marie , Kirkhus Bente
Published: January 2008

Abstract—

The cell cycle traverse of epidermal basal cells 24 h after in vivo exposure of ultraviolet B (UVB) irradiation was studied by immunochemical staining of incorporated bromodeoxyuridine (BrdU) and bivariate BrdU/DNA flow cytometric analysis. The results were compared with the cell kinetic patterns following topical application of the skin carcinogen methylnitrosourea (MNU) as well as the skin irritant cantharidin. Hairless mice were injected intraperitoneally with BrdU 24 h after treatment of their back skin with either a minimal erythema dose of UVB, or a single application of MNU or cantharidin dissolved in acetone. The cell cycle traverse of the BrdU‐labelled cohorts of epidermal basal cells were then followed for the subsequent 12 h. At 6 h after BrdU‐injection, when all labelled cells in the control group as well as in the cantharidin group had left the S phase, the bivariate distributions of the UVB‐exposed and the MNU group showed that BrdU‐positive cells were still present in S phase. Hence, UVB irradiation, similar to the carcinogen MNU, prolonged the S phase duration in some of the basal cells. At 12 h after pulse labelling, however, BrdU‐positive cells from UVB‐exposed mice were re‐entering S phase from Gl phase, indicating that UVB irradiation induced a shortening of the cell cycle time as well, similar to the response observed after cantharidin. The present data can not tell whether these cells also were delayed in S phase. Thus, the cell cycle traverse in hairless mouse epidermis 24 h after in vivo exposure to UVB seemed to be a combination of the cell kinetic effects following chemical skin carcinogens and skin irritants. UVB irradiation induced both a delay in transit time through S phase, probably due to DNA damage and subsequent repair, as well as a reduction in the total cell cycle time consistent with rapid regenerative proliferation.
UPTAKE and PHOTODYNAMIC EFFICIENCY OF HEM ATOPORPH YRIN, HYDROXYETHYLVINYLDEUTEROPORPHYRIN and HEMATOPORPHYRIN DERIVATIVE (PHOTOFRIN II®): A STUDY WITH ISOLATED MITOCHONDRIA
Authors: Dellinger M. , Vever‐Bizet C. , Brault D. , Moreno G. , Salet C.
Published: January 2008

Abstract— The uptake of Photofrin II® (PFII), hematoporphyrin (Hp) and hydroxyethylvinyldeuter‐oporphyrin (HVD) by isolated mitochondria was studied using the high performance liquid chromatography (HPLC) technique. The various PFII components show a high affinity for mitochondria. At 5.75 μg/ml PFII, their ratio of incorporation was found to be very similar, except for Hp which is about two times less incorporated. These results were reproduced with pure Hp and pure HVD. The uptake of Hp and HVD increases with concentration but, while that of Hp reaches a plateau, the uptake of HVD continues to increase. At a high porphyrin concentration (˜ 10−5M), the loss of respiratory control is obtained with the same light dose for Hp and PFII. Taking into account the uptake and the known photophysical parameters of the various porphyrins, the photodynamic efficiency of HVD seems equivalent to that of Hp. The present results and known data on cell photoinactivation suggest that the activity of these porphyrins is mainly dependent on their incorporation.
DEPOLARIZATION OF MOUSE MYELOMA CELL MEMBRANES DURING PHOTODYNAMIC ACTION
Authors: Specht K. G. , Rodgers M. A. J.
Published: January 2008

Abstract— The effect of photodynamic action on plasma membranes was examined using a fluorescent potentiometric indicator [di‐SBA‐C2(3)] to measure alterations in the plasma membrane potential of mouse myeloma cells treated with zinc phthalocyanine sulfonate and light. Plasma membrane depolarization was observed to be an early event in photodynamic action, showing both photosensitizer concentration and light dose dependence. Depolarization occurred while membrane integrity was retained and appears to be an early event preceding cell death.
SYNTHESIS OF POSITIVELY CHARGED PHTHALOCYANINES and THEIR ACTIVITY IN THE PHOTODYNAMIC THERAPY OF CANCER CELLS
Authors: Wöhrle D. , Iskander N. , Graschew G. , Sinn H. , Friedrich E. A. , Maier‐Borst W. , Stern J. , Schlag P.
Published: January 2008

Abstract— Positively charged zinc containing or metal free phthalocyanines 6a‐c and 7a‐c were prepared via a three step procedure starting from 4‐nitrophthalonitrile. The phthalocyanines contain alkyl chains of different length in order to influence the hydrophilic vs lipophilic character of the compounds. The partition between a hydrophilic (water) and lipophilic (octanol‐1) phase was determined, and the photoredox activities were investigated. Initial results on the photodynamic activity of these compounds were compared with those of Dougherty's Photofrin II on different malignant and non‐malignant cell lines (XP 29MAmal, CXI, HeLa, S180 and N017). Positively charged phthalocyanines in vitro showed a higher photodynamic activity than Photofrin II.
THE POLYAMINES OF Xanthium strumarium and THEIR RESPONSE TO PHOTOPERIOD
Authors: Hamasaki Nobuko , Galston Arthur W.
Published: January 2008

Abstract— Flowering plants of Xanthium strumarium L., grown in 8 h photoperiods, were analysed for polyamines. Putrescine, spermidine and spermine were found throughout the plant in three forms: (a) as free polyamines; (b) conjugates soluble in 5% trichloracetic acid (TCA); and (c) bound to the TCA‐insoluble precipitate. On a fresh weight basis, total polyamines are most abundant in young leaves and buds, especially flower buds. Spermidine predominates in the free polyamine fractions, while spermine is dominant in the conjugated fraction. Transfer of vegetative plants from 16 h photoperiods to 1, 2, 3 or 4 inductive cycles (8 h light + 16 h uninterrupted dark) caused rapid and marked changes in the polyamine titer of the leaves and ultimately, floral initiation. The titer of free putrescine per mg protein declined progressively with induction in all leaf sizes, while the titers of free spermidine and spermine rose during days 2 and 3 in small and expanding leaves. Conjugated putrescine, spermidine and spermine rose sharply after only 1 inductive cycle, especially in small and expanding leaves, and maintained the higher level for at least several cycles. In plants given 4 inductive cycles, buds harvested after 4 additional days had sharply elevated levels of conjugated polyamines, especially spermine, on a protein basis.
WAVELENGTH DEPENDENCE OF HEMATOPORPHYRIN DERIVATIVE PHOTODYNAMIC TREATMENT EFFECTS ON RAT EARS
Authors: Star Willem , Versteeg Jeanne , Putten Wim Van , Marunissen Hans
Published: January 2008

Abstract— The in vivo wavelength dependence of hematoporphyrin derivative (HpD) photodynamic treatment (PDT) has been studied. Ears of 136 rats were treated at six red and four blue‐green laser wavelengths (615‐635,488–514.5 nm). Hematoporphyrin derivative was administered intraperitoneally (15 mg/kg) and 24 h later both ears were irradiated, at different wavelengths, for t=6.5, 10 or 15 min at 60 mW/cm2. Four parameters (thickness, average erythema, eschar and loss of tissue) were quantified and a combined score (CS) of effects was established statistically. The maximum combined score during follow‐up was taken as a measure for the biological effect. The light distribution in rat ears during irradiation with red and blue‐green light was estimated from in vivo measurements and the transport theory. Statistical analysis of the combined score data yielded values for the relative biological effectiveness (RBE). Relative biological effectiveness maxima occurred at 501.7 and 625 nm. Analyzing erythema and loss of tissue separately yielded maxima at the same wavelengths. Quantitative agreement between the latter two sets of relative biological effectiveness values was obtained only when they were referred to the actual light energy fluence in tissue, rather than to the incident fluence. These relative biological effectiveness values are about 2.3 at 501.7 nm and 1.35 at 625 nm, taking relative biological effectiveness = 1 at 630 nm.
ACTION SPECTRA FOR THE GENERATION OF SINGLET OXYGEN FROM MITOCHONDRIAL MEMBRANES FROM SOYBEAN (Glycine max) HYPOCOTYLS
Authors: Jung Jin , Kim Hee‐Jung , Cho Moonjae
Published: January 2008

Abstract— The action spectrum for the generation of singlet oxygen (1O2) from mitochondrial membranes under aerobic conditions was measured at wavelengths between 360 and 600 nm, using sub‐mitochondrial particles (SMP) prepared from soybean hypocotyls. The spectrum, showing a peak at about 420 nm, remarkably resembles the absorption spectra of the Fe‐S centers of nonheme iron proteins. Disruption of the Fe‐S centers by treating SMP with mersalyl acid resulted in a substantial decrease in the efficiency of 1O2 generation, leaving an action spectrum whose pattern is significantly similar to the absorption spectrum of flavins, at least in the region of near UV and blue light wavelengths. Estimating the contribution of the Fe‐S centers to the generation of 1O2 from SMP, we suggest that the Fe‐S centers act as very important endogenous photosensitizers in plant cells, in so far as the type II mechanism is concerned. Possible involvement of mitochondrial flavoproteins in the generation of 1O2 is also discussed.
TIN ETIOPURPURIN DICHLORIDE‐SENSITIZED LIPID PHOTOOXIDATION OF ERYTHROCYTE MEMBRANES
Authors: Morgan Alan R. , Cheng L. S. , Skalkos Dimitris , Garbo Greta M.
Published: January 2008

Abstract— Tin(IV) etiopurpurin dichloride (SnET2‐2Cl) is a photosensitizer which has been shown to be an effective photodynamic agent for the treatment of transplantable animal tumors in vivo. The purpose of this study was to understand the effect of SnET2‐2Cl on membrane lipid peroxidation. When erythrocyte membranes were exposed to visible light in the presence of SnET2‐2Cl, lipid peroxidation was observed. An accumulation of lipid hydroperoxides and an increase in lipid fluorescence were also observed. Thin layer chromatography of lipid extracts from photooxidized membrane revealed photoperoxide products derived from phospholipid. Investigations into the mechanism(s) of lipid peroxidation by SnET2 2Cl and light‐sensitized membranes were also performed. Results indicate that singlet oxygen (1O2) plays a major role in lipid peroxidation.
ANNUAL EXPOSURES TO CARCINOGENIC RADIATION FROM THE SUN AT DIFFERENT LATITUDES and AMPLIFICATION FACTORS RELATED TO OZONE DEPLETION. THE USE OF DIFFERENT GEOMETRICAL REPRESENTATIONS OF THE SKIN SURFACE RECEIVING THE ULTRAVIOLET RADIATION
Authors: Dahlback Arne , Moan Johan
Published: January 2008

Abstract— In most calculations of annual fluences of carcinogenic light as well as of the radiation amplification factor and of biological amplification factors associated with ozone depletions, the radiation is assumed to fall on a horizontally oriented plane surface. This is obviously a bad approximation of the surface of the human body. In order to evaluate the importance of using a realistic geometric representation of the surface of the human body we here present calculations of the flux of carcinogenically effective radiation falling on three different bodies: a vertically standing cylinder, a sphere and a horizontally oriented surface. The exposure to carcinogenic radiation depends strongly on the surface geometry. However we find that the radiation amplification factors are almost independent of the surface geometry chosen. The biological amplification factors for the three geometrical representations are also similar to within 20%. The total amplification factor for the increase in the incidence of non‐melanoma skin cancer related to ozone depletion is about 17% larger when a cylindrical representation is used compared to when a plane horizontal surface is considered.
THE PHOTOSENSITIZERS BENZOPHENOXAZINE and THIAZINES: COMPREHENSIVE INVESTIGATION OF PHOTOPHYSICAL and PHOTOCHEMICAL PROPERTIES
Authors: Becker Ralph S. , Chakravorti Sankar , Das Suresh
Published: January 2008

Eight differently substituted title dye compounds have been investigated regarding intersystem crossing, triplet state, fluorescence and singlet excited state pKa properties. In general, non‐halogenated oxazines and thiazines as well as a mono bromooxazine show very low triplet quantum yields, φT (lT 0.03) and relatively long triplet lifetimes (‐40 μs) in acidic methanol. The φT data correlate well with known singlet oxygen yields. In basic methanol no triplet transient is observed but a significant yield of a ground state transient protonated (base dye) form is produced with a short lifetime, ‐400 ns. Fluorescence can be seen simultaneously from both the excited base and the protonated base dye forms in basic methanol. For iodinated oxazine or thiazines, the triplet yield increases and can be as high as 0.5 (diiodo case) in acidic methanol. The triplet lifetimes are further shortened to ‐10 μs compared to the non‐iodinated derivatives above. The triplet yields of the iodo compounds are higher or equal to known singlet oxygen yields. In basic methanol triplet yields up to 0.2 can be seen, the triplet lifetime are shortened still further to 1 μs but no observable protonated form is produced (in distinction to the non‐iodinated cases). Consideration is given to the correlation of triplet and singlet oxygen yields, ground and excited pKa properties, spin‐orbit coupling and internal conversion properties, solvent effects, and phototherapeutic activity of these dyes.
ELECTROCHEMICAL LUMINESCENCE WITH N(5)‐ETHYL‐4a‐HYDROXY‐3‐METHYL‐4a, 5‐DIHYDROLUMIFLAVIN. THE MECHANISM OF BACTERIAL LUCIFERASE
Authors: Kaaret Thomas W. , Bruice Thomas C.
Published: January 2008

It has been proposed in the literature that the chemiluminescence of the flavoenzyme of bacterial luciferase is caused by a chemically initiated electron‐exchange luminescence mechanism which provides an excited 4a‐hydroxy‐4a,5‐dihydroflavin ([4a‐FlHOH]*) as product of le− reduction of the radical 4a‐FlHOHt. Electrochemical/photon counting experiments were performed to assess the feasibility of this proposal. Potentials for step‐wise oxidation of N(5)‐ethyl‐4a‐hydroxy‐4a,5‐dihydroluminfiavin (4a‐FlEtOH) have been determined in dry N,N‐dimethylformamide (DMF). Photon counting was carried out during the le− reduction of 4a‐FlEtOH+ in both DMF and acetonitrile by use of an apparatus consisting of a photocell mounted below a Pt ring‐disk electrode. By use of the ring‐disk electrode a steady state concentration of [4a‐FlEtOH]* could be maintained by continuous le oxidation of 4a‐FlEtOH +→ 4a‐FlEtOH+ and le− reduction of 4a‐FlEtOH+→ 4a‐FlEtOH. A maximum of 14% collection (theoretical maximum is 18%) of FlEtOH+ at the ring electrode was obtained below 5000 rotations per minute. Calibration of the apparatus using 9,10‐diphenylanthracene allowed approximation of the quantum yield for le− reductive capture of 4a‐FlEtOrP as lO−6 to 10−4 in DMF and 10−7 to 10−5 in acetonitrile. No fluorescence for 4a‐FlEtOH in DMF could be observed; if fluorescent, the efficiency of 4a‐FlEtOH can be no greater than − 3 × 10−5. No electrogenerated chemiluminescence is observed on the electrochemical recycling of FlEt+→ FlEt2+ and FlEt2+→ FlEt+.
A FLUORESCENCE STUDY OF THE INTERACTION OF INDOLIC COMPOUNDS WITH SYNTHETIC POLYELECTROLYTES
Authors: Zimerman Oscar E. , Cosa Juan J. , Previtali Carlos M.
Published: January 2008

Abstract— –The interaction of indole derivatives with synthetic polyelectrolytes was investigated using UV absorption and fluorescence spectroscopy. The presence of both sodium poly(styrene sulfonate) (PSS) and sodium polyvinyl sulfonate) (PVS) inhibits the fluorescence quenching of 1‐pyrene sulfonic acid by tryptamine. The effect is more marked for PSS than for PVS. There was no polyelectrolyte effect on the quenching by tryptophan. It was also found that aromatic polyelectrolytes strongly quench the fluorescence of indole derivatives of opposite charge by a static mechanism. This is accompanied by a new absorption in the red extreme of the UV spectrum of the mixtures. The systems investigated were tryptamine‐PSS and polyvinyl benzyl trimethylammonium chloride) with the anions of indole‐3‐alkanoic acids. Equilibrium constants for the binding of the indole derivatives to the polyelectrolytes were determined. The fluorescence of zwitterionic tryptophan is not affected by the presence of the polyelectrolytes.
PHYTOCHROME INDUCTION OF PHOTOREACTIVATING ENZYME IN Phaseolus vulgaris L. SEEDLINGS*
Authors: Langer Bernd , Wellmann Eckard
Published: January 2008

Abstract— Photoreactivating enzyme (PRE) activity was measured in hypocotyls of Phaseolus vulgaris L. seedlings using a radioimmunoassay for thymine dimers. In dark‐grown seedlings a five‐fold increase in PRE activity was observed after 6 h of irradiation with blue or far‐red light. Short time irradiations with red light were also effective. Reversibility of this red‐light‐effect by a subsequent short term irradiation with far‐red light and also the high effectiveness of continuous far‐red light indicate that PRE activity is under phytochrome control. This observation points to PRE induction via gene activation.
STUDIES ON THE MECHANISM OF THE HEMATOPORPHYRIN‐SENSITIZED PHOTOOXIDATION OF 1,3‐DIPHENYLISOBENZOFURAN IN ETHANOL and UNILAMELLAR LIPOSOMES
Authors: Reddi Elena , Valduga Giuliana , Rodgers Michael A. J. , Jori Giulio
Published: January 2008

The 5μM hematoporphyrin‐sensitized photooxidation of 1,3‐diphenylisobenzofuran (DPBF) was studied in homogeneous ethanolic solutions and in aqueous dispersions of unilamellar liposomes of dipalmitoylphosphatidylcholine; both the porphyrin and DPBF are embedded in the phospholipid bilayer. The rate and quantum yield of DPBF photooxidation were found to increase upon increasing the substrate concentration and were higher in the liposome system, while they were unaffected by the fluidity of the phospholipid bilayer. Time‐resolved spectroscopic measurements showed that the photooxidation of DPBF in ethanol solution proceeds by a type II O2(1Δg)‐involving mechanism. In the liposomal vesicles the high local concentration of hematoporphyrin (Hp) and DPBF in the phospholipid bilayer (ca 2000‐fold higher than the stoichiometric concentration) enhances the probability of energy transfer from triplet Hp to DPBF with generation of triplet DPBF; hence O2(1Δg) formation can be promoted by both triplet Hp and triplet DPBF. A minor fraction of triplet DPBF quenchings appears to generate radical species which propagate DPBF damage by chain reaction.
LONG PERSISTENCE OF MONOFUNCTIONAL 8‐METHOXYPSORALEN‐DNA ADDUCTS IN HUMAN SKIN in vivo
Authors: Ortel Bernhard , Maytum Daniel J. , Gange Richard W.
Published: January 2008

Human skin can be persistently photosensitized by topical application of aqueous 8‐methoxypsoralen plus immediate irradiation with a non‐erythemogenic dose of wavelengths above 380 nm. Re‐exposure of skin thus sensitized to broadband UV‐A produces phototoxic erythema72–120 h later. The persistence of the photosensitization was demonstrated by phototoxic erythema after re‐exposure up to 15 days after the first sensitizing irradiation. According to the concept that the first exposure induces primarily psoralen monoadducts, we consider this an investigation of psoralen monoadduct persistence. In contrast to several earlier studies, this sensitive method indicates that psoralen monoadducts may remain in human skin in vivo for more than 2 weeks after formation.
FERROUS ION RELEASE FROM FERRITIN BY ULTRAVIOLET‐A RADIATIONS
Authors: Aubailly M. , Santus R. , Salmon S.
Published: January 2008

Ferritin is the principal protein of iron storage (in the Fe(III) state). The UV‐A irradiation of 0.25 μM ferritin solutions (from horse spleen) loaded with 530 μM Fe(III) induces Fe2+ release in the medium. The initial quantum yield is wavelength dependent (φ(365 nm) − 2 times 10−3) but pH and oxygen independent. The Fe2+ release reaches a plateau which strongly depends on pH and oxygen. The amino acid composition of the apoprotein is not altered by the UV irradiation. Addition of formate ions enhances the Fe2+ production, suggesting that the ferritin photoreduction involves an electron transfer from an OH− ligand. The possible importance of this phenomenon in skin photo‐biology is discussed.
DYNAMIC LINEAR DICHROISM IN CHROMOPROTEINS
Authors: LYLE PAUL A. , STRUVE WALTER S.
Published: January 2008

Abstract—

The time‐dependent polarized fluorescence and optical density transients arising from electronic excitation transport are derived for solutions of randomly oriented chromoproteins in which the chromophore transition moments have well‐defined orientations with respect to the protein. The treatment is extended to oriented monolayers of chromoproteins, in which the molecules are aligned with a particular protein‐fixed axis perpendicular to the surface plane and with random azimuthal angles about the surface normal. The initial ratio of parallel to perpendicular transients is invariably 3:1, irrespective of system dimensionality and chromophore organization. The residual anisotropy observed at long times is directly related to the relative orientations of the donor and acceptor chromophores. These calculations form a basis for detailed interpretation of ultrafast fluoresence and pump‐probe linear dichroism studies in photosynthetic systems, for which 3‐dimensional structures are becoming increasingly available.