bluuebunny/crossref_metadata_2025 huggingface dataset:
WAVELENGTH DEPENDENCE FOR AMT CROSSLINKING OF pBR322 DNA
Authors: Gasparro Francis P. , Saffran Wilma A. , Cantor Charles R. , Edelson Richard L.
Published: January 2008

Abstract The wavelength dependence for 4′aminomethyl‐4,5′,8‐trimethylpsoralen crosslinking of a linearized plasmid DNA (pBR322) by narrow band UV‐A light (298–382 nm) has been determined. Maximal levels of crosslinking occurred with light in the 322–346 nm range. Crosslinks were shown to be photoreversible by shorter wavelength photons (298 and 310 nm). The correlation between the wavelength dependence for crosslink formation and the optimal wavelength for most psoralen action spectra further supports the notion that crosslinks are the major lesion responsible for the effectiveness of psoralen plus ultraviolet A therapies.
FORWARD SCATTERING PROPERTIES OF HUMAN EPIDERMAL LAYERS
Authors: Bruls Wiel A. G. , Van Der Leun Jan C.
Published: January 2008

Abstract From an optical point of view the outermost skin layers contain numerous structures by which penetrating radiation may be scattered as well as absorbed. The nature and strength of this scattering may strongly influence the extent of penetration. We illuminated samples of stratum corneum and full‐thickness epidermis with collimated radiation and measured the angular intensity distribution of the transmitted radiation; we did this in the ultraviolet for several angles of incidence, and in the visible for perpendicular incidence only. Skin samples were obtained from the skin of the lower back and upper leg of Caucasian volunteers. Epidermis and subsequently stratum corneum were separated by chemical methods. In the case of stratum corneum, the angular intensity distribution of the transmitted radiation peaks strongly at all wavelengths, in approximately the direction of the incident radiation, that has been refracted at the surface of the sample. With full‐thickness epidermis, the distribution of the transmitted radiation also peaks, though less strongly than with stratum corneum. These features suggest a forward oriented scattering mechanism. Both in the case of stratum corneum and full‐thickness epidermis, the angular distribution flattens towards the shorter wavelengths and with increasing thickness. The wavelength dependence suggests that both scattering and absorption increase towards the shorter wavelengths. The existence of a thickness dependence indicates that volume scattering occurs. Hydration of stratum corneum is found to influence its scattering properties. Dry samples scatter less than hydrated samples. The consequences of our findings for modelling skin optics are briefly discussed.
ELECTRON SPIN ECHO ENVELOPE MODULATION OF THE TRANSIENT EPR SIGNALS OBSERVED IN PHOTOSYNTHETIC ALGAE AND CHLOROPLASTS*
Authors: Thurnauer Marion C. , Clark Carl
Published: January 2008

Phase memory decays were obtained from the transient signals sampled within 50 ns of laser excitation by time resolved electron spin echo (ese) spectroscopy in normal protonated, deuterated, deuterated 15N photosynthetic algae and broken chloroplasts. Previously, it has been shown that application of time resolved ese to study these systems, in particular, gives rise to two kinds of signals (standard and special ese). The standard ese signal at g = 2.0023 and the special ese signal exhibit similar electron spin echo envelope modulation (eseem). The modulation frequency and pattern can be identified with that obtained from stable oxidized P700 in the same system. The two lower field resonances of the standard ese signal do not show eseem. The results support the proposed mechanism for formation of special ese and the notion that the standard ese is due to at least two radicals. It is also demonstrated that we can observe eseem of P+700 under ambient temperature conditions.
PHOTODYNAMIC EFFECTS: PORPHYRIN VS CHLORIN
Authors: Kessel David , Dutton Christopher J.
Published: January 2008

The photosensitizing properties of mesoporphyrin were compared with those of a structurally‐related chlorin, bonellin. Using Sarcoma‐180 tumor cells in culture and irradiation at 610–660 nm, we observed a 10‐fold greater efficiency of photodynamic inactivation by the chlorin. This result was correlated with differences in absorption spectra of the two compounds, not with differences in extent and loci of intracellular accumulation.
ENHANCEMENT OF PORPHYRIN‐PHOTOSENSITIZATION OF YEAST CELLS BY ETHANOL
Authors: Ito Takashi , Ito Atsushi
Published: January 2008

AbstractIn porphyrin photosensitization, the localization of porphyrin in the cell and the sensitizing activity have been of recent concern. Hydrophobic porphyrins are usually in a highly aggregated state in aqueous systems. This study was designed to see whether the change in the polarity of the environment by adding ethanol could modify the sensitizing effects of porphyrins using a fermentable (alcohol tolerant) yeast (Saccharomyces cerevisiae) cells. The results showed that (1) the addition of ethanol (˜15%) to the aqueous suspension remarkably increased inactivation and cell membrane damage both in the hematoporphyrin (HP) and protoporphyrin (PP) photosensitizations, and (2) a sharp induction of genetic changes occurred concomitantly both in HP and PP sensitized cells in the presence of ethanol. In view of the fact that the addition of ethanol modified the absorption spectra and fluorescence intensity of porphyrins in favor of deaggregation, these results may be interpreted to mean that deaggregation of porphyrins promoted by ethanol enhanced their solubility in the lipophilic environment of the cell membrane and even further inside, thereby increasing the sensitizing activities.
ACUTE SKIN RESPONSE IN ALBINO MICE FOLLOWING PORPHYRIN PHOTOSENSITIZATION UNDER OXIC AND ANOXIC CONDITIONS
Authors: Gomer Charles J. , Razum Nicholas J.
Published: January 2008

Abstract Acute normal skin toxicity induced by porphyrin photosensitization has been examined using albino mice. Oxic and anoxic (clamped) skin was exposed to red light (630 nm) 24 h following administration of hematoporphyrin derivative (HpD) or Photofrin II (the active component of HpD). Experiments were also performed to determine the effect of sodium pentobarbital anesthesia on HpD and Photofrin II photosensitization of normal skin. Results from this study demonstrated that comparable levels of acute skin damage were induced by HpD and Photofrin II under oxic conditions but neither porphyrin produced any apparent phototoxicity under anoxic conditions. In addition, the level of skin damage induced by porphyrin photosensitization was not affected by sodium pentobarbital anesthesia.
PHOTOSENSITIZATION OF MELANIN: AN ELECTRON SPIN RESONANCE STUDY OF SENSITIZED RADICAL PRODUCTION AND OXYGEN CONSUMPTION
Authors: Sealy R. C. , Sarna T. , Wanner E. J. , Reszka K.
Published: January 2008

Abstract Rose Bengal is shown to photosensitize free‐radical production and oxygen consumption in solutions of melanin from autooxidation of 3,4‐dihydroxyphenylalanine (DOPA). In anaerobic solutions the sensitizer enhances rates of free‐radical production by up to a factor of 20. In aerobic solutions, rates of oxygen consumption can be increased by a factor of several hundred. The reactions appear to involve the triplet state of the sensitizer. The effect of the sensitizer in increasing oxygen consumption is quenched by low concentrations of azide and enhanced by D2O, suggesting that a singlet oxygen mechanism is involved.
AMIODARONE PHOTOTOXICITY TO HUMAN ERYTHROCYTES AND LYMPHOCYTES
Authors: HASAN Tayyaba , E. Kochevar Irene , Abdulah Dorina
Published: January 2008

Amiodarone (AD) therapy for cardiac arrhythmia frequently leads to cutaneous phototoxicity. Amiodarone and its metabolite, desethylamiodarone (DEA), photosensitized hemolysis of red blood cells (RBC) and were phototoxic to lymphocytes. Hemolysis photosensitized by 3.3 μM AD was partially oxygen dependent and was partially quenched 5 mM sodium azide, 50 mM mannitol, superoxide dismutase (251 U/mee) and catalase (1500 U/me), but was unaffected when H2O was replaced by D2O. These results suggest that membrane damage may be important in the in vivo phototoxicity to AD, that both oxygen dependent and oxygen independent mechanisms may operate, and that active oxygen species such as O2 and hydrogen peroxide may be involved. Photohemolysis was more rapid in the presence of DEA than of AD. However, this may be due to the greater fragility of the cell membrane in the presence of DEA. The greater phototoxicity of DEA than AD towards lymphocytes was not due to greater membrane fragility.
THE EFFECTS OF EXOGENOUS CATALASE ON BROAD‐SPECTRUM NEAR‐UV (300‐400 nm) TREATEDEscherichia coli CELLS
Authors: Sammartano Lauri J. , Tuveson R. W.
Published: January 2008

Abstract —Catalase incorporated into plating medium protects against inactivation and mutagenesis by broad‐spectrum near‐ultraviolet wavelength (300‐400 nm) (NUV) radiation in strains of Escherichia coll. Plating medium containing catalase does not provide protection against inactivation by wavelengths in the FUV region. Catalase added to the cell suspension during or added immediately after NUV exposure also protects against inactivation. The protection provided by catalase suggests a possible role for hydrogen peroxide in the processes of inactivation and mutagenesis by broad‐spectrum NUV.
CELLULAR BINDING OF HEMATOPORPHYRIN DERIVATIVE IN HUMAN BLADDER CANCER CELL LINES: KK‐47
Authors: MIYOSHI NORIO , HISAZUMI HARUO , UEKI OSAMU , NAKAJIMA KAZUYOSHI
Published: January 2008

Abstract— The fluorescence lifetime and degree of fluorescence polarization of hematoporphyrin derivative (HpD) have been investigated using different solutions: organic and micellar solutions. Ham's F12 medium, and KK‐47 cell suspension. The lifetime and polarization degree in organic and micellar solutions did not change with increasing incubation time, but the polarization degree in the cell suspensions temporarily increased at the initial incubation time and then decreased 4 h after incubation. The lifetime in the cell suspensions exhibited a bi‐phasic exponential decay. The results obtained suggested that mainly dimeric HpD may bind weakly to the cell membrane, and then slowly be distributed throughout the cytoplasm. The polarity and viscosity of the intracellular loci containing HpD were evaluated from the fluorescence polarizations of HpD in MeOH‐H2O mixtures and ethylene glycol(EG)‐MeOH mixtures. The dielectric constant and viscosity of the loci containing HpD were 35 and 11 cp, respectively. Accordingly, the intracellular location of HpD were considered relatively hydrophilic loci of the cells.
GIANT CELL FORMATION IN BLADDER TUMOR CELLS FOLLOWING HEMATOPORPHYRIN DERIVATIVE‐SENSITIZED PHOTOIRRADIATION
Authors: BELLNIER DAVID A. , LIN CHI‐WEI
Published: January 2008

Abstract—Giant cell induction was studied in cultured bladder tumor cells (MGH‐Ul; commonly referred to as “EJ”) following hematoporphyrin derivative (HpD)‐sensitized photoirradiation. Eight days after treatment, control colonies (no treatment, HpD alone, light alone) were generally uniform in size and density and contained few giant cells. Colony heterogeneity and giant cell frequency increased with light dose in the presence of HpD. The morphology and frequency of giant cell formation, with respect to survival levels, were comparable to those observed in 280 kVp X‐irradiation of the same cells.
COMPARATIVE STUDIES ON THE LETHAL, MUTAGENIC, AND RECOMBINOGENIC EFFECTS OF ULTRAVIOLET‐A,‐B,‐C, AND VISIBLE LIGHT WITH AND WITHOUT 8‐METHOXYPSORALEN IN Saccharomyces cerevisiae
Authors: Mondon P. , Shahin Majdi M.
Published: January 2008

Abstract

Genetic effects of UV‐A, UV‐B, UV‐C, and the combination of 8‐methoxypsoralen (8MOP) with UV‐A or visible light were studied in the haploid strain XV185–14C and diploid strain D5 of Saccharomyces cerevisiae. The induction of his+, lys+, and horn+ reverse mutations was measured in strain XV185–14C. In strain D5 we measured the induction of genetically altered colonies, particularly twin spot colonies arising from a mitotic crossing‐over. UV‐C and UV‐B induced point mutations at the three loci in the haploid strain and mitotic crossing‐over and other genetic alterations in the diploid strain. UV‐C was more mutagenic and recombinogenic than UV‐B. UV‐A or visible light alone did not induce genotoxic effects at the doses tested. However, UV‐A plus 8‐MOP produced lethal and mutagenic effects in the haploid strain XV185–14C, although mutagenic activity was less than that of UV‐B. Visible light plus 8‐MOP also induced genotoxic effects in strain XV185–14C. In the diploid strain D5, UV‐A plus 8‐MOP induced a higher frequency of genetic alterations than UV‐B at comparative doses. Visible light plus 8‐MOP was also genetically active in strain D5. The haploid strain was more sensitive to the lethal effects of UV‐C, UV‐B, UV‐A, and impure visible light plus 8‐MOP than the diploid strain.
THE INWARD H+ PATHWAY IN BACTERIORHODOPSIN: THE ROLE OF M412 AND P(N)560 INTERMEDIATES
Authors: Danshina S. V. , Drachev L. A. , Kaulen A. D. , Skulachev V. P.
Published: January 2008

Abstract

In purple bacteriorhodopsin sheets adsorbed onto the phospholipid‐impregnated collodion film, electrogenic stages are identified correlating with decays of the M and N(P)‐type intermediates. It is concluded that both M N and N bR transitions are electrogenic.

The M decay is shown to be of a complex kinetics. In purple sheets, the lower the light intensity, the higher the rate of “slow M” decay. Such a dependence, which is absent from monomeric bacteriorhodopsin in proteoliposomes and from Triton X‐100‐solubilized protein, may be explained by the inhibiting effect of a light‐induced conformation change in a bacteriorhodopsin molecule upon the M decay in some other bacteriorhodopsin molecules within the same sheet.

The light intensity‐independent “slow M” decay in solubilized bacteriorhodopsin is shown to correlate with the decay of the N intermediate and H+ uptake after the flash. In contrast to “fast M”, “slow M” is pH dependent, closely resembling in this respect the N intermediate. It is suggested that there is a fast light‐independent equilibration between M and N so that “slow M” represents the portion of the M pool that monitors the N concentration. The M N equilibrium is assumed to be involved in the effect of the light‐induced electric field on the M decay. No direct effect of light on the equilibrium was found.
EFFECT OF PSORALEN + ULTRAVIOLET‐A ON THE CHEMOTACTIC ACTIVITY OF POLYMORPHONUCLEAR NEUTROPHILS TOWARDS ANAPHYLATOXIN C5a DES ARG
Authors: Esaki Kenji , Mizuno Nobuyuki
Published: January 2008

Abstract

It was shown that psoralen + UV‐A inhibits the chemotactic activity of polymorphonuclear neutrophils towards anaphylatoxin C5a des Arg. This reaction required oxygen and there is a high possibility that the active oxygen species was in a singlet state. Oxygen did not act directly on C5a des Arg, but rather produced oxidized psoralen which inhibited C5a des Arg activity. The effect was dependent on the concentration and types of psoralen and on the UV‐A dose. Among the psoralens, the inhibitory effect of 4,5′,8‐trimethylpsoralen was the strongest, followed by 8‐methoxypsoralen and 3‐carbethoxypsoralen and finally 4,4′,6‐trimethylangelicin. Psoralen + UV‐A failed to inhibit the chemotactic activity towards chemotactants other than anaphylatoxin C5a such as casein, the cultured filtrate of E. coli, platelet‐activating factor, leukotriene B4, 5‐hydroxy‐6,8,11,14‐eicosatetraenoic acid and 12‐L‐hydroxy‐5,8,10,14‐eicosatetraenoic acid.
QUANTUM YIELDS AND KINETICS OF THE PHOTOBLEACHING OF HEMATOPORPHYRIN, PHOTOFRIN II, TETRA(4‐SULFONATOPHENYL)‐PORPHINE AND UROPORPHYRIN
Authors: Spikes John D.
Published: January 2008

Abstract

Porphyrins used as sensitizers for the photodynamic therapy (PDT) of tumors are progressively destroyed (photobleached) during illumination. If the porphyrin bleaches too rapidly, tumor destruction will not be complete. However, with appropriate sensitizer dosages and bleaching rates, irreversible photodynamic injury to the normal tissues surrounding the tumor, which retain less sensitizer, may be significantly decreased. This paper surveys the quantum yields and kinetics of the photobleaching of four porphyrins: hematoporphyrin (HP), Photofrin II (PF II), tetra(4‐sulfonatophenyOporphine (TSPP) and uroporphyrin I (URO). The initial quantum yields of photobleaching, as measured in pH 7.4 phosphate buffer in air, were: 4.7 × 10‐5, 5.4 × 10‐5, 9.8 × 10‐5, and 2.8 × 10‐5for HP, PF II, TSPP and URO respectively; thus, the rates of photobleaching are rather slow. Low oxygen concentration (2 μM) significantly reduced the photobleaching yields. However, D2O increased the yields only slightly, and the singlet oxygen quencher, azide, had no effect, even at 0.1M.Photosensitizing porphyrins in body fluids, cells and tissues may be closely associated with various photooxidizable molecules and electron acceptors and donors. Therefore, selected model compounds in these categories were examined for their effects on porphyrin photobleaching. A number inhibited and/or accelerated photobleaching, depending on the compound, the porphyrin and the reaction conditions. For example, 1.0 mMfurfuryl alcohol increased the photobleaching yields of HP and URO more than 5‐fold, with little effect on PF II or TSPP. In contrast, the electron acceptor, methyl viologen, increased the photobleaching yield of TSPP more than 10‐fold, with little accelerating effect on the other porphyrins. These results suggest that the mechanism(s) of the photobleaching of porphyrin photosensitizers in cells and tissues during PDT may be complex.
PHOTOREACTIVATION OF UV‐KILLING IN Vibrio parahaemolyticus WP28*
Authors: Okaichi Kumio , Ohnishi Takeo , Nozu Keiichi
Published: January 2008

Abstract— Vibrio parahaemolyticus WP28 cells possess efficient photoreactivation (PR) from U V‐killing. The action spectrum of PR in these cells is quite analogous to that in Escherichia coli cells, which have a broad efficient range from 350 to 425 nm with a maximum at 375 nm. PR at 315 nm is also significantly present.
RICH GROWTH MEDIUM ENHANCES ULTRAVIOLET RADIATION SENSITIVITY and INHIBITS CELL DIVISION IN ssb MUTANTS OF Escherichia coli K‐12
Authors: Wang Tzu‐chien V. , Smith Kendric C.
Published: January 2008

Abstract— –DNA single‐strand binding protein mutants (ssb) of Escherichia coli K‐12 exhibit much greater UV radiation sensitivity when plated on rich medium (RM) than when plated on minimal medium (MM). However, when comparing UV‐irradiated ssb‐113 cells (previously known as exrB and lexC113) incubated in RM vs MM, no difference was observed in DNA degradation or in the repair of incision breaks that arose during excision repair. Although UV‐irradiated ssb‐113 cells incubated in RM did resume DNA synthesis slightly sooner than those incubated in MM, and there was a small increase in the production of DNA double‐strand breaks in these cells, the most dramatic difference noted, however, was the much enhanced filamentation of irradiated cells incubated in RM vs MM. Therefore, we suggest that most of the RM‐enhanced U V radiation sensitivity in ssb‐113 cells is due to an inhibitory effect of RM on cell division rather than on DNA repair.
DIFFERENT (DIRECT and INDIRECT) MECHANISMS FOR THE INDUCTION OF DNA‐PROTEIN CROSSLINKS IN HUMAN CELLS BY FAR‐ and NEAR‐ULTRAVIOLET RADIATIONS (290 and 405 nm)
Authors: Peak Meyrick J. , Peak Jennifer G. , Jones Carol A.
Published: January 2008

Abstract— Apparent DNA‐protein crosslinking induced by monochromatic 290 and 405 nm Tadiations was measured in cultured human P3 teratocarcinoma cells with DNA alkaline elution techniques. The rates of the induction of crosslinks by 290 nm radiation were the same when the cells were irradiated either aerobically or anaerobically or when the cells were in an H2O or D2O aqueous environment. With 405 nm radiation, anaerobic irradiation reduced the induction of the crosslinks (dose modifying factor is about 0.2), and about twice as many crosslinks were observed when the cells were irradiated in an environment of D2O rather than H2O. The results are consistent with the hypothesis that far‐UV radiation induces DNA‐protein crosslinks by a direct mechanism, whereas near‐UV radiation induces crosslinks via indirect photodynamic photosensitizations in which unidentified cellular endogenous photosensitizers and reactive species of oxygen are used.
IN VIVO and POST MORTEM MEASUREMENTS OF THE ATTENUATION SPECTRA OF LIGHT IN MAMMALIAN TISSUES
Authors: Wilson Brian C. , Jeeves W. Patrick , Lowe Diane M.
Published: January 2008

Abstract— The attenuation of light in rabbit liver and striated muscle and in pig brain has been measured in the wavelength range400–800 nrn. A variable‐wavelength monochromatic light source was used to illuminate the surface of the exposed tissues in situ. Optical fibers, coupled to a single photon counter, were positioned within the tissues at different depths to determine the distribution of light flux along the central axis of the light beam. The wavelength‐dependence of attenuation was measured in vivo, and changes occurring in the attenuation spectra immediately post mortem were recorded. Strong absorption bands were observed around 425 nm and 550 nm in all three tissues, both in vivo and post mortem. At longer wavelengths, the attenuation decreased slowly, and no significant structure was observed. Substantial changes occurred immediately post mortem, particularly in the absorption bands. These effects are attributed mainly to de‐oxygenation of blood, and changes in blood concentration in the tissues. The implications for light dosimetry in photodynamic therapy are discussed.
COMPARATIVE STUDY OF ERYTHEMA RESPONSE TO UVA RADIATION IN GUINEA PIGS and HUMANS*,†
Authors: Whitman Gail B. , Leach Eileen Enny , DeLeo Vincent A. , Fleiss Joseph L. , Conetta Barbara , Harber Leonard C.
Published: January 2008

Abstract— Cutaneous erythema resulting from UVB radiation has been extensively studied in both humans and experimental animals; however, although there have been several investigations defining UVA erythema in humans, there have been no comprehensive reports using an animal model. Accordingly, studies were designed to assess UVA erythema in terms of time of onset; time of maximum reaction; and fluence‐response relationships in albino guinea pigs and to compare these with similar studies in humans.

Two high intensity Hg vapor lamps containing iron and gallium halides were used as UVA light sources. Both have sufficient fiuence rates (190 to 260 W m−2) so as to allow convenient exposure times for delivery of UVA erythemogenic fluences. UVA fluences of 20 times 104, 40 times 104 and 60 times 104 J m−2 were administered to 58 humans and 51 Hartley‐strain albino guinea pigs.

Data obtained in humans indicate that UVA erythema develops immediately after irradiance with a maximum erythema peak occurring in 6 to 12 h and markedly diminishing by 24 h. The minimal fiuence required to elicit erythema responses in Type I and Type II individuals was found to be approximately 40 times 104 J m−2 of UVA when observed at 6 h, a fiuence about 1000 times greater than that used to elicit UVB erythema.

Studies in 51 guinea pigs demonstrated erythema immediately after irradiance, with a peak between 8 to 12 h, and a marked decrease in 48 h. The fiuence of UVA required to elicit erythema was similar to that required in humans. The two different light sources provided comparable data per unit exposure and were essentially similar to a Xe lamp.

These data from both humans and guinea pigs strongly support the concept that UVA erythema can be assayed in guinea pigs and correlated with humans.
BIOLOGICAL ACTIVITIES OF PHTHALOCYANINES–III. PHOTOINACTIVATION OF V‐79 CHINESE HAMSTER CELLS BY TETRASULFOPHTHALOCYANINES*
Authors: Brasseur N. , Ali H. , Autenrieth D. , Langlois R. , Liert J. E. van
Published: January 2008

Abstract—Tetrasulfophthalocyanine and a series of its metal chelates were tested for their ability to photoinactivate V‐79 Chinese hamster cells. Incubation of cells for 1 h with tetrasulfophthalocyanine at 5 μMeffectively sensitized cells towards red light. At the 1% survival level, the dye was 4 x more efficient than hematoporphyrin, efficiency being defined in terms of drug concentration in the medium and incident light fluence rather than on the basis of quanta absorbed. Chelation of the dye with metal ions resulted in most cases in a greatly diminished photosensitizing effect, except for cerium. The cerium complex was about 5 x more effective for cell killing than the metal free tetrasulfophthalocyanine and 20 x more efficient as compared to hematoporphyrin. Hypoxic conditions resulted in total loss of photoactivity indicating the involvement of oxygen in the action mechanism. The inactivation by near‐UV light by these drugs was also investigated. The potential of sulfonated phthalocyanines as novel photosensitizers for photodynamic cancer therapy is discussed.
POLARIZED PHOTOACOUSTIC SPECTRA OF PHYCOERYTHRIN and PHYCOCYANIN IN ANISOTROPIC POLYMER FILMS
Authors: Frackowiak Danuta , Hotchandani Surat , Bialek‐Bylka G. , Leblanc Roger M.
Published: January 2008

Abstract—Photoacoustic spectra (PAS) of biliproteins, namely, R‐phycoerythrin (PE) and C‐phycocyanin (PC) and their mixture in anisotropic and isotropic polyvinylalcohol (PVA) films were measured under the illumination with polarized and natural light. Also samples in deuterated PVA were investigated. The yields of fluorescence of various chromophores of investigated biliproteins were obtained from PAS, absorption, fluorescence and fluorescence lifetime measurements. The deuteration of samples causes different changes in thermal deactivation of excitation of various chromophores. Ratios of PAS to absorption of the light polarized parallel and perpendicular to the direction of film stretching are different. The PAS amplitude of deuterated samples is higher than that for undeuterated.
THE EFFECT OF DEUTERIUM OXIDE ON THE FLUORESCENCE AND PHOTOTRANSFORMATION OF 124 kDALTON PHYTOCHROME*
Authors: Moon Doo‐Khil , Jeen Gwang‐Soo , Song Pill‐Soon
Published: January 2008

Abstract— To probe the nature of primary photoprocess and the mechanism of the phototransformation of undegraded 124 kDa oat phytochrome, solvent deuterium isotope effects on the fluorescence and phototransformation of phytochrome have been investigated. The fluorescence intensity and lifetime of phytochrome (Pr form) are greater in D20‐buffer than in H2O‐buffer, suggesting a possible involvement of proton transfer in the primary photoprocess of phytochrome. Although the photostationary equilibrium (Pr to Pfr ratio) was not altered by deuterium oxide, in contrast to degraded phytochrome, the rate constants of both transformations, Pr→ Pfr and Pfr→ Pr were enhanced by up to 24%. The Pr to Pfr phototransformation of degraded phytochrome, however, was retarded by about the same percentage in D2O. These opposite effects of D2O with degraded and undegraded phytochromes underscore the fact that the Pr form from the former reverts to the Pr form in the dark, apparently catalyzed by deuterated general and/or conjugate acidic group(s). With the degraded phytochrome the deuterium oxide enhancement of the rate of dark reversion was approximately 2‐fold (Sarkar and Song, 1981).

Both the fluorescence intensity and the rates of phototransformation of phytochrome were enhanced in D2O with successive photocyclings (Pr→ Pfr→ Pr→ Pfr→ Pr etc.) with alternating red and far‐red irradiation. It has been proposed that successive photocycling of phytochrome in D2O results in proton‐deuteron exchange in the partially exposed Ptr chromophore and/or its surrounding amino acid residues.
ON THE TRIPLET‐TRIPLET ENERGY TRANSFER FROM CHLOROPHYLL TO CAROTENE IN TRITON X 100 MICELLES
Authors: Chauvet Jean‐Paul , Bazin Marc , Santus René
Published: January 2008

Abstract— The kinetics of the triplet‐triplet energy transfer of chlorophyll α (Cha) to β carotene (Car) has been investigated in Triton X100 micelles by 353 nm laser flash photolysis. This transfer consists of an intramicellar process involving pigment species located in the same micelle. A kinetic model using a bimolecular treatment leads to a rate constant of the energy transfer in the micellar phase (ktm≅ 6 × 108M‐1 s‐1) lower than the previously determined values in homogeneous solvents (kt≅ 4.6 ≅ 109M‐ls‐l); this result shows the high microviscosity of the micellar core. In addition, the apparent bimolecular rate constant (kt≅ 5.0 ≅ 1010M‐l s‐1) appears to be an order of magnitude higher than in homogeneous solvents. The lifetime of the carotene triplet state is the same in the hydrophobic core of Triton X100 micelles (τa= 7.7 μs) as in organic solvents (hexane or carbon disulfide). The transfer yield is controlled by the distribution of chlorophyll and carotene molecules in the micelles.
ELECTRICAL and EMISSION PROPERTIES OF CHLOROPHYLL a IN PLANAR ASYMMETRICAL MEMBRANES
Authors: Robert Sylvain , Tancrède Pierre , Houle André , Leblanc Roger M.
Published: January 2008

Abstract—We have designed and constructed an experimental set‐up allowing the simultaneous determination of the electrical and fluorescence properties of pigments incorporated in asymmetrical lipid bilayers formed from monolayers. The system is composed of two Langmuir troughs machined in an annealed Teflon block. Each trough is mounted with a movable barrier for the compression of the monolayers as well as with a float type Langmuir torsion balance to measure the surface properties of the monolayers prior to membrane formation. The trough is also equipped with optical windows which permit the localization of a laser beam on the reconstituted membrane incorporating the chromophore. The reconstituted bilayers are further characterized by measurement of their specific resistance and capacitance properties. A detailed description of the experimental method proposed is given, stressing the main advantages of our technique. Finally preliminary results on asymmetrical phosphatidylethanolamine/phosphatidylserine bilayers incorporating chlorophyll‐a molecules are presented and discussed.
THE REACTIVITY OF SUPEROXIDE (O2‐) and ITS ABILITY TO INDUCE CHEMILUMINESCENCE WITH LUMINOL
Authors: Merenyi G. , Lind J. , Eriksen T. E.
Published: January 2008

Abstract— The quantum yield and the kinetics of O‐induced luminol chemiluminescence was investigated in a broad pH interval at varying luminol and concentrations. It is suggested that the weak chemiluminescence observed is mediated via a luminol‐superoxide‐adduct proposed to be an a‐hydroxyperoxyl radical. At pH 7 the maximum quantum yield of chemiluminescence per initial percent was determined to be 4 times 10‐8. The degree of involvement in phagocytosis and related processes should be viewed against this maximum limit.
ABSORPTION OF METHYLBACTERIOPHEOPHORBIDE a SINGLE CRYSTALS: SPECTRAL SHIFTS DUE TO π‐π INTERACTIONS
Authors: Hanson Louise Karle , Hofrichter James
Published: January 2008

Abstract— Polarized absorption spectra were obtained for a single crystal of methylbacteriophorbide a (MeBPhide a). The Qy band is red‐shifted ? 1660 cm‐1 (? 110 nm) relative to MeBPhide a in a CH2Cl2/benzene solution. This is equivalent to the largest red shifts observed for in vivo bacteriochlorophyll a. The Soret band exhibits a smaller red shift and a significant reduction in intensity, and the Qx band is not observed. The crystal spectra are qualitatively similar to spectra reported for several other aggregated (bacterio)chlorophyll and bacteriopheophytin systems. Since crystalline MeBPhide a contains no Mg, water or hydrogen bonding (Barkigia etal., 1981), these results demonstrate that the spectral changes associated with the aggregation of photosynthetic chromophores can arise solely from IT‐IT interactions between macrocycles.
ON THE PREPARATION and PROPERTIES OF DIHEMATOPORPHYRIN ETHER, THE TUMOR‐LOCALIZING COMPONENT OF HPD*
Authors: Kessel David , Cheng May‐Ling
Published: January 2008

Abstract—A porphyrin mixture derived from hematoporphyrin and termed HPD (hematoporphyrin derivative) is used for localization and therapy of tumors. The major localizing component of HPD has been provisionally identified as a dihematoporphyrin ether (DHE). In this study, we describe HPLC procedures for analytical and preparative separation of HPD components. Optimal conditions for DHE formation were determined. A comparison of absorbance and fluorescence spectra in different solvents indicate that DHE aggregates are substantially more stable than are the analogous hematoporphyrin structures. Studies on the interaction between DHE and tumor cells indicate an initial binding of the drug at lipophilic membrane sites, followed by gradual relocation to intracellular loci.
THE PHOTOMOVEMENT OF Caenorhabditis elegans, A NEMATODE WHICH LACKS OCELLI. PROOF THAT THE RESPONSE IS TO LIGHT NOT RADIANT HEATING
Authors: Burr A. H.
Published: January 2008

Abstract— Caenorhabditis elegans adults were tested at constant temperature with 10 s periods of monochromatic light alternated with 20 s dark periods. Stimuli at effective intensities and wavelengths caused an increase in the frequency of ecclitic (phobic, avoidance) responses, which was measured as an increase in the probability of a temporary reversal in direction of movement. For monochromatic stimuli ranging from 420 to 680 nm at a constant 56 picoeinsteins s‐1 cm‐2, only those at520–600 nm elicited significant responses. At 540 nm the threshold fluence rate was approximately 30 pE s‐1 cm‐2. At saturating intensities the mean reversal probability was increased to 0.20 in 10 s from a background level of 0.12. approximately.

Because C. elegans lacks ocelli and is very sensitive to temperature, possible sources of radiant heating were considered in detail, including (a) infrared present in the stimuli, (b) absorption of light by the arena, and (c) absorption of light by a nematode pigment. All possible sources were found to cause a negligible temperature rise, on the order of or less than the natural temperature fluctuations inside the worm, 1.5 times 10‐6°C. A 2 times 10‐4°C temperature rise produced by a 1230 nm infrared stimulus had no significant effect on reversal frequency. It was concluded that the response to illumination must have been to light, and not to temperature changes.

Large, + or ‐ 2 °C changes from the acclimation temperature caused significant increases in the background frequency of ecclitic responses (a thermoecclisis or thermoklinokinesis). However, neither the threshold nor the saturation level of light‐induced responses was affected by the ± 2°C changes.
FLUORESCENCE OF Euglena gracilis PHOTORECEPTOR PIGMENT: AN in vivo MICROSPECTROFLUOROMETRIC STUDY
Authors: Ghetti Francesco , Colombetti Giuliano , Lenci Francesco , Campani Enzo , Polacco Erseo , Quaglia Maurizio
Published: January 2008

Abstract— The spectroscopic characterization of the photoreceptor pigment is one of the main questions in the study of the photosensory transduction chains in photomotile microorganisms. One of the possible techniques that can be used is in vivo microspectrofluorometry. By means of a tunable dye‐laser microspectrofiuorometer developed by us, we have investigated some of the spectroscopic properties of the photoreceptor pigment of the green flagellate Euglena gracilis. The in vivo fluorescence excitation spectrum has been determined and the fluorescence quantum yield has been measured. The results show that flavins are indeed present in the paraflagellar body of E. gracilis and that their fluorescence quantum yield is much lower than that of a free flavin. An estimate of the order of magnitude of the rate constants for primary molecular reactions is tentatively given.
TIME‐RESOLVED FLUORESCENCE STUDIES OF SPINACH CHLOROPLASTS–EVIDENCE FOR THE HETEROGENEOUS BIPARTITE MODEL
Authors: Berens Sylvia J. , Scheele Jurgen , Butler Warren L. , Magde Douglas
Published: January 2008

Abstract—Fluorescence lifetimes of spinach chloroplasts were measured with a modelocked dye laser and time‐correlated single photon counting. Information about energy transport and functional organization of the chloroplasts is revealed by such time‐resolved fluorescence studies. Quenching experiments using treatment with UV light or the chemical agent dibromothymoquinone are consistent with the notion that there is heterogeneity associated with PS II units and that such heterogeneity is reflected over the entire time range of fluorescence decay, not just in a single component. Phosphorylation experiments were also carried out which permit us to relate these kinetic studies to previous steady state observations.
HPLC ANALYSIS OF 4′,5′‐MONOADDUCT FORMATION IN CALF THYMUS DNA and SYNTHETIC POLYNUCLEOTIDES TREATED WITH UVA and 8‐METHOXYPSORALEN
Authors: Gasparro Francis P. , Bagel Jerry , Edelson Richard L.
Published: January 2008

Abstract—8‐methoxypsoralen monoadduct formation in calf thymus DNA irradiated with subbands of ultraviolet A light has been quantitated by HPLC analysis of the enzymatic hydrolysates of the DNA. Normalization of the yield of monoadducts for the variation in source output and the absorptivity of 8‐MOP at each of the irradiating wavelengths showed that the 4′,5′‐furan monoadduct was the principal photoproduct and the efficiency of its formation was independent of irradiating wavelength. Synthetic polynucleotides irradiated with ultraviolet A light demonstrated a base composition and sequence dependence for 8‐MOP photoreactivity: (poly(dAdT.dAdT) > poly(dA.dT) > poly(dGdC.dGdC) in both the B and Z forms > pofy(dT).
PHOTOCHEMISTRY OF THE PHOTOTOXIC POLYACETYLENE PHENYLHEPTATRIYNE*
Authors: Weir D. , Scaiano J.C. , Arnason J.T. , Evans C.
Published: January 2008

Abstract— Investigation of the photochemistry of the phototoxic polyacetylene phenylheptatriyne, PHT, was undertaken to obtain further information on competing photo‐oxidative type II and non‐oxidative processes observed in vivo. Laser excitation (308 or 337 nm) led to the formation of a strong triplet signal with a lifetime of 28 μs in MeOH. The triplet was efficiently quenched by the triplet quencher 1,3‐octadiene (kq ‐ 1.6 × 109M‐1s‐1). Quenching by O2 occurred with a rate constant (1.7 × 109M‐1s‐1) comparable to the rate of electron transfer to methylviologen (1.4 × 109M‐1 s‐1). The formation of singlet oxygen established earlier (type II reaction) in the former case and the semioxidized PHT radical in the latter case are consistent with the competing phototoxic processes observed in vivo.
WAVELENGTH DEPENDENCE OF ULTRAVIOLET RADIATION‐INDUCED MORTALITY AND K+ EFFLUX IN CULTURED CELLS OF Rosa damascena
Authors: Murphy Terence M. , Hurrell Helen C. , Sasaki Tamara L.
Published: January 2008

Abstract— The sensitivity of the colony‐forming ability of rose‐cell cultures (Rosa damascena L. cv Gloire de Guilan) to ultraviolet radiation has been measured for wavelengths from 240‐334 nm. These cultures are much less sensitive than bacteria and animal cells in the region from 240‐310 nm, an observation attributed to the presence in rose cells of ultraviolet‐radiation‐absorbing compounds. The effect of the same wavelengths on K+ efflux was also measured and compared to the spectrum for lethality. K+ efflux or damage leading to K+ efflux might contribute to lethality at wavelengths longer than 290 nm but not at shorter wavelengths.
FREE RADICAL PRODUCTION BY CHLORPROMAZINE SULFOXIDE, AN ESR SPIN‐TRAPPING AND FLASH PHOTOLYSIS STUDY
Authors: Buettner Garry R. , Motten Ann G. , Hall Robert D. , Chignell Colin F.
Published: January 2008

Abstract— Using the spin‐trapping technique we have investigated the photolysis of chlorpromazine sulfoxide and promazine sulfoxide. Photolysis of these sulfoxides in aqueous solution resulted in a species which is capable of oxidizing ascorbate, cysteine, glutathione, NADH, and azide by one electron, in addition to extracting hydrogen atoms from ethyl alcohol and dimethyl sulfoxide. These oxidations were not dependent on the presence of dissolved oxygen. The oxidizing species is proposed to be the hydroxyl free radical arising from the homolytic cleavage of the S‐O bond of the sulfoxide. Flash photolysis of the chlorpromazine and promazine sulfoxides demonstrated the formation of cation radicals consistent with the loss of the hydroxyl radical from the sulfoxides. In addition we present a simple direct method for the quantitative synthesis of promazine and chlorpromazine sulfoxides from the parent promazine derivatives.
LASER FLASH PHOTOLYSIS STUDIES OF DNA‐COMPLEXED ETHIDIUM BROMIDE
Authors: Atherton Stephen J. , Beaumont Paul C.
Published: January 2008

Abstract—Laser flash photolysis studies of DNA‐complexed ethidium bromide were undertaken. We have observed a singlet‐singlet (S1‐Sn) absorption process for DNA‐complexed ethidium bromide. The observed lowest singlet excited state lifetime was 21 ± 2 ns. The molar difference extinction coefficient was measured to be 2.4 ± 0.4 × 103M‐1cm‐1at 370 nm. The assignment of this transition was confirmed by time resolved fluorescence measurements.
INDUCTION OF CROSS‐LINKS IN VIRAL DNA BY NATURALLY OCCURRING PHOTOSENSITIZERS
Authors: Altamirano‐Dimas M. , Hudson J. B. , Towers G. H. N.
Published: January 2008

Abstract—Six different photosensitizers were compared for their ability to form cross‐links in murine cellular DNA and murine cytomegalovirus DNA, in the presence of long wave UV radiation. The viral DNA was in the form of free DNA or intact virions. The compounds consisted of the linear furanocoumarins 8‐methoxypsoralen (8‐MOP) and isopimpinellin; the angular furanocoumarin, angelicin; the two furanochromones, visnagin and khellin; and the β‐carboline alkaloid, harmine. Cross‐linking was assessed by alkaline agarose gel electrophoresis and hydroxyapatite chromatography. 8‐MOP produced extensive cross‐linking (as expected), as did isopimpinellin. Visnagin produced less cross‐linking, such that not all DNA molecules were affected at the concentrations used. Khellin, angelicin and harmine produced no detectable cross‐linking. The same result was obtained for DNA which was treatedin situin the virion. To some degree there was a correlation between the amount of cross‐linking and the relative potency of anti‐MCMV infectivity. But other factors evidently contribute to the phototoxic effect of these compounds.
2,4‐DIAMINO‐6‐PTERIDINECARBOXALDEHYDE AND AN AZOBENZENE DERIVATIVE ARE PRODUCED BY UV PHOTODEGRADATION OF METHOTREXATE
Authors: Chahidi C. , Giraud M. , Aubailly M. , Valla A. , Santus R.
Published: January 2008

Abstract— 2,4‐Diamino‐6‐pteridinecarboxaldehyde, aminopterin and an azobenzene derivative have been identified as methotrexate photoproducts. A mechanism involving photosensitized oxidation by the aldehyde is proposed for the production of these three products.
DARK INTERACTION AND OXYGEN DEPENDENT PHOTOBINDING BETWEEN AN AROMATIC TETRAPEPTIDE AND DNA MODIFIED BY 5‐ METHOXYPSORALEN MONOADDUCTS
Authors: Morliere P. , Cremer J. , Toulme J. J. , Santus R. , Dubertret L.
Published: January 2008

The binding of the tetrapeptide lysyl‐tryptophyl‐glycyl‐lysinet‐butyl ester to native DNA and DNA photochemically modified by 5‐methoxypsoralen has been investigated by fluorescence spectroscopy. The peptide exhibits a higher affinity for the modified DNA than for the undamaged DNA. This is due to the presence of strong stacking sites in the vicinity of 5‐methoxypsoralen monoadducts. Upon irradiation at 365 nm of the peptide‐modified DNA complexes, a cross‐linking of the peptide to the nucleic acid is observed. This photochemical addition requires the presence of oxygen and involves, in part, singlet oxygen.
PHOTOCHEMISTRY OF THE BOTANICAL PHOTOTOXIN, α‐TERTHIENYL AND SOME RELATED COMPOUNDS*
Authors: Evans C. , Weir D. , Scaiano J. C. , Eachern A. Mac , Arnason J. T. , Morand P. , Hollebone B. , Leitch L. C. , Philogegne B. J. R.
Published: January 2008

The photochemistry of α‐terthienyl (αT) and its mono‐ and dodo derivatives has been examined using nanosecond laser Hash photolysis techniques. The triplet states of these intermediates have been characterized, and show strong triplet‐triplet absorptions with maxima in the 450 to 490 nm region. The triplet lifetimes are normally reduced by efficient triplet‐triplet annihilation and self‐quenching both of which approach diffusion control. Triplet lifetimes in methanol obtained by extrapolation to zero laser dose and zero concentration are 30, 12.5 and 9.4 μs for αT and its mono‐ and dodo derivatives, respectively; the effect of iodo substitution on the lifetimes is attributed to heavy atom effects. The triplet states are efficiently quenched by oxygen and the electron acceptor methyl viologen, while amines tire very poor triplet quenchers. The iodo derivatives are photolabile. undergoing C‐I bond cleavage from the singlet state, a process that was studied in benzene solvent, where the complex between iodine atoms and benzene can be readily characterized.

Modification of αT by replacement of the central thiophene ring by an aromatic ring (i.e. DTB) causes drastic changes in the triplet and singlet state kinetic and spectroscopic characteristics.
A MICROSPECTROFLUOROMETRIC STUDY OF PORPHYRIN‐PHOTOSENSITIZED SINGLE LIVING CELLS— I. MEMBRANE ALTERATIONS
Authors: Reyftmann J. P. , Kohen E. , Morliere P. , Santus R. , Kohen C. , Mangel W. F. , Dubertret L. , Hirschberg J. G.
Published: January 2008

Microspectrofluorometry on single living cells reveals that the primary effects of porphyrin‐photosensitization on membranes results in the production of fluorescent lipofuscin‐like pigments implying important lipid photoperoxidation. These fluorescent products (max450 nm) can also be formed in the dark after the irradiation of the cell. Their formation is abolished not only by crocetin and Tigason, two long‐chain polyenes, but also by chloroquine. The latter, although a lysosomotropic drug, cannot inhibit the photosensitized permeation of lysosomal membranes which occurs at the beginning of the irradiation as shown by the splitting of fluorogenic substrates by lysosomal proteinases or by β‐galactosidase when added before or after irradiation.
FURTHER STUDIES ON THE ANTIVIRAL ACTIVITY OF HARMINE, A PHOTOACTIVE β‐CARBOLINE ALKALOID
Authors: Hudson J. B. , Graham E. A. , Fong R. , Hudson L. L. , Towers G. H. N.
Published: January 2008

The UV‐A mediated antiviral effect of harmine was investigated using murine cytomegalovirus (MCMV) as the target. Virus, which had been inactivated by harmine + UVA, was used to infect cultured mouse cells, and various stages in the viral replication cycle were examined. No viral protein synthesis or RNA synthesis (as measured by polyacrylamide gel electrophoresis or DNA‐RNA hybridization) could be detected, and the viral DNA did not replicate (measured by DNA‐DNA hybridization). In contrast virus which had been treated with harmine in the dark promoted a complete growth cycle in mouse cells.

An attempt was made to identify the primary target of harmine + UVA activity by examining the bacteriophages T4 and M13, which unlike MCMV do not possess membranes. Both bacteriophages were sensitive, but the single‐stranded DNA phage M13 was considerably more so. These results, together with others discussed in the text, suggest that DNA and possibly other macromolecules can serve as targets for harmine photoactivity.
SITES OF PHOTOSENSITIZATION BY DERIVATIVES OF HEMATOPORPHYRIN
Authors: Kessel David
Published: January 2008

Leukemia L1210 cells were incubatedin vitrowith the tumor‐localizing product HPD (hem‐atoporphyrin derivative) for 0.5. 4 and 18 h. Effects of subsequent irradiation on viability, membrane transport and integrity, DNA synthesis and intracellular ATP concentration were assessed. Intracellular porphyrin pools were analyzed by HPLC. A 30 min incubation led to concentration of a readily‐exchangeable pool of monomeric HPD components at plasma membrane loci; irradiation resulted in photodamage to membrane transport and a loss in capacity for dye exclusion. In contrast, increasing the incubation time led to a corresponding increase in the size of a non‐exchangeable intracellular pool of other HPD components. Subsequent irradiation led to depletion of intracellular ATP and loss of capacity for biosynthesis of DNA, but little plasma membrane damage.