bluuebunny/crossref_metadata_2025 huggingface dataset:
THE SITE‐SPECIFIC INHIBITION OF Bgl I CLEAVAGE BY PSORALEN PHOTOADDUCTS
Authors: Ostrander Elaine A. , Robinson Gordon W. , Isaacs Stephen T. , Tessman John , Hallick Lesley M.
Published: January 2008

Abstract— We have investigated the site specificity of furocoumarins by using fluorescent densitometry to examine the frequency of cleavage by the restriction enzyme Bgl I. This enzyme has an 11 base pair (bp) recognition sequence which varies slightly from site to site because it includes a 5 base pair neutral region. Cleavage at all three Bgl I recognition sites in pBR322 was inhibited by the photoaddition of the psoralen derivative 4′‐hydroxymethyl‐4,5′,8‐trimethylpsoralen (HMT) which forms both crosslinks and monoad‐ducts in a dose‐dependent manner. One site, which contains two thymidines in a crosslinkable configuration, was observed to be markedly more sensitive to HMT photoadducts. In contrast Bgl I cleavage at all sites was relatively resistant to the derivative 5‐methylisopsoralen (5‐MIP), which forms only monoadducts. When HMT‐reacted DNA was generated with widely different ratios of monoad‐ducts to crosslinks (3% and 40% crosslinks), essentially the same level and pattern of inhibition was observed in both cases. Taken together, the data imply that differences in inhibition seen at the three cutting sites of Bgl I with HMT are attributable to DNA sequence and the role it plays in adduct positioning.
DRUG SENSITIZATION: PHOTOBINDING OF SULFANILAMIDE TO BOVINE SERUM ALBUMIN
Authors: Bec Jean Louis , Delrieu Pascal , Abravanel Gérard , Paillous Nicole
Published: January 2008

Abstract— Photobinding of sulfanilamide to bovine serum albumin (BSA) was investigated by irradiating BSA and buffered BSA/drug solutions with UV light (Λ= 300 nm) under anaerobic conditions. The protein solutions were then denatured and the unbound sulfanilamide removed. Marked differences in the UV and fluorescence spectra of the solutions before and after irradiation were observed, suggesting covalent binding of the drug to BSA. This was confirmed using [14C]labelled sulfanilamide. The extent of photobinding of sulfanilamide determined using the radiolabeled drug, was concentration dependent. The binding ratio varied from 3 mol drug per mol BSA for a 10‐4M drug concentration, to 10 mol drug per mol BSA for 10‐2M drug concentration.

The protein solutions were hydrolysed under acid conditions and the amino acids obtained were analysed by ion exchange chromatography. The hydrolysate of irradiated BSA (10‐4M) ‐sulfanilamide (10‐2M) mixture lost about 10 mol of cystine per mol of BSA. This loss was not observed after hydrolysis of irradiated alone or non‐irradiated BSA. Irradiation of cystine with [14C]sulfanilamide in HC1 solutions produced the same compound as was found after hydrolysis of irradiated BSA/sulfanilamide mixtures. This was demonstrated by autoradiography of paper chromatograms. The same compound was also detected in an irradiated [35S]cystine non‐labelled sulfanilamide mixture. It was not detected, however, after irradiation of a mixture of all amino acids of BSA excluding cystine. These data suggest that cystine residues are involved in the photobinding of sulfanilamide (or its photoproducts) to BSA.
EFFECT OF MID‐UV RADIATION ON DNA‐Cu2+ COMPLEX: ABSORPTION AND CIRCULAR DICHROISM STUDY
Authors: Matzeu Mirella , Onori Giuseppe
Published: January 2008

Abstract— When DNA is complexed with Cu2+ ions it becomes sensitized to mid‐UV light. Irradiation of the complex at 310 ± 10 nm produces marked changes in absorption and circular dichroism spectra in addition to those in melting profiles of irradiated samples. These variations show conformational changes in DNA structure due to a photoreduction of some copper sites in the DNA‐Cu2+ complex. In addition to this effect an irreversible damage in DNA structure could be invoked to explain the observed behaviour. These facts can be related to the presence in DNA‐Cu2+ complex of a small absorption band extending up to mid‐UV range while the absorption of DNA is negligible in this spectral range.
CONFORMATIONAL CHANGES OF BOVINE LENS CRYSTALLINS IN A PHOTODYNAMIC SYSTEM
Authors: Andley Usha P. , Chapman Susan F.
Published: January 2008

Abstract— Conformational changes of bovine lens crystallins in a photodynamic system generating singlet oxygen, have been investigated. The formation of intersubunit crosslinks was observed in all three classes (α‐, β and γ‐) of crystallins by irradiation in the presence of the photosensitizer methylene blue. Near‐UV circular dichroism (CD) spectra of the crystallins were significantly altered by irradiation under these conditions, indicating changes in tertiary structure but the far‐UV CD remained unchanged suggesting that the secondary structure ((β‐sheet conformation) remains unchanged. Significant changes in the absorption and fluorescence spectra were also observed. Measurement of total sulfhydryl content showed a decrease of 27%, 50% and 37% for α‐, β‐ and γ‐crystallins respectively, after irradiation. Fluorescence lifetime measurements of N‐iodoacetyl‐N'‐(5‐sulfo‐l‐naphthyl)ethylenediamine‐labeled crystallins showed a significant decrease of the lifetime of the major decay components of the label bound to sulfhydryl groups of α‐ and γ‐crystallins, but showed no change in the microenvironment of the sulfhydryl groups of β‐crystallin. The results are consistent with the microenvironments of the tryptophan and sulfhydryl groups predicted from sequence studies.
TEMPORAL SHIFTS IN BIOLUMINESCENCE EMISSION SPECTRA FROM THE DEEP‐SEA FISH, Searsia koefoedi
Authors: Widder E. A. , Latz M. I. , Herring P. J.
Published: January 2008

Abstract— The luminescence of freshly collected exudate from the post‐cleithral organ of the deep‐sea searsiid fish. Searsia koefoedi, was increased in intensity by the addition of hydrogen peroxide and exhibited emission maxima at 408 nm and 478 nm. Initially, the spectrum was unimodal with a long wavelength peak and a short wavelength shoulder. With time, the short wavelength peak increased in relative magnitude; the spectrum became bimodal, then the short wavelength peak predominated. The measured time‐dependent changes in the spectral distribution resulted from differences in the rates of decay of the two peaks. The short wavelength peak exhibited first order exponential decay with a mean (± standard deviation) decay constant of ‐0.13 ± 0.02 min‐1 (N= 4). Decay of the long wavelength peak proceeded approximately twice as fast and was best defined by a double exponential function.
IN VIVOFLUORESCENCE OF TUMORS AFTER TREATMENT WITH DERIVATIVES OF HEMATOPORPHYRIN
Authors: Kessel David
Published: January 2008

Abstract—Administration of a mixture of porphyrins termed HPD (hematoporphyrin derivative) to mice bearing the Lewis lung tumor leads to preferential accumulation of fluorescence at tumor lociin vivoafter 48 h. HPLC analysis shows that the fluorescent species consist of hematoporphyrin and its dehydration products. But injection of these porphyrins does not lead to fluorescence localization. The intracellular fluorescence which is observed apparently arises from intracellular degradation of the tumor‐localizing component of HPD. These fluorescent species represent only a small fraction of the total accumulated porphyrin pool; a larger weakly‐fluorescent porphyrin pool is also present, and may be the major factor in tumor photosensitization.
PROPOSED STRUCTURE OF THE TUMOR‐LOCALIZING FRACTION OF HPD (HEMATOPORPHYRIN DERIVATIVE)
Authors: Kessel David
Published: January 2008

Abstract— Synthesis of the tumor‐localizing preparation HPD (hematoporphyrin derivative) results in the formation of dimers and oligomers of hematoporphyrin joined by labile linkages. Studies with HPD and an HPD analog containing the chlorin analog of mesoporphyrin suggest the presence of two different linkages, either of which yields a tumor‐localizing product. One such linkage is apparently derived from a hematoporphyrin‐based oligomer present in commercial preparations of hematoporphyrin as an impurity. The other linkage is formed during the chemical steps leading to the conversion of hematoporphyrin to “HPD”.
APPEARANCE OF PHOTOPHOSPHORYLATION CAPACITY: THRESHOLD vs GRADED CONTROL BY PHYTOCHROME
Authors: Oelze‐Karow Heidemarie , Mohr Hans
Published: January 2008

Abstract— It is shown that in attached mustard cotyledons graded control of chlorophyll synthesis by physiologically active phytochrome (Pfr) and threshold control by Pfr of the ‘potential capacity’ to photophosphorylate are totally different phytochrome actions even though both controls are essential for the build‐up of the same functional complex, the machinery for photophosphorylation. The essential findings are as follows: The action of Pfr (made by a 1 min red light pulse) on the capacity and efficiency of photophosphorylation is rapid—detectable after 15 min and completed after 30 min—whereas the action of Pfr on chlorophyll formation is slower—only detectable 45 min after the original red light pulse (R). Detailed escape studies (loss of full reversibility of the inductive effect of a R pulse by far‐red) show that the effect of a R pulse on chlorophyll synthesis remains fully reversible for 45 min whereas the action of Pfr on the capacity for photophosphorylation is very fast (occurring within 2 min). Control of capacity for photophosphorylation is a threshold response (whereby the threshold value is approximately 1.25% Pfr based on total phytochrome at 36 h = 100%) whereas control by Pfr of chlorophyll synthesis is graded. Control of capacity for photophosphorylation by Pfr only operates if the hypocotyl hook is connected to the cotyledons for at least 2 min after the inductive R pulse, i.e. until full escape from reversibility has occurred, whereas chlorophyll formation in the cotyledons is not affected by the separation of hook and cotyledons.
VACUUM ULTRAVIOLET NATURAL AND MAGNETIC CIRCULAR DICHROISM WITH CONVENTIONAL SOURCES AND SYNCHROTRON RADIATION
Authors: Snyder Patricia Ann
Published: January 2008

Vacuum ultraviolet natural and magnetic circular dichroism measurements have added significantly to our knowledge of the geometric and electronic structure of molecules and have provided a better understanding of the correct approach for theoretical calculations. In this review, I define natural and magnetic circular dichroism, and discuss information obtained with these techniques. The instrumentation for vacuum ultraviolet natural and magnetic circular dichroism is reviewed, from its beginning with conventional sources to the present time use of synchrotron radiation. The future possibilities and challenges for these measurements are examined with particular reference to making measurements to higher energies.
WAVELENGTH DEPENDENCE FOR THE INACTIVATION OF ATP IN THE VACUUM‐ULTRAVIOLET REGION ABOVE 140 nm
Authors: Ito Atsushi , Taniguchi Taketoshi , Ito Takashi
Published: January 2008

Radiation effects were investigated on the activity and the structure of adenosine triphosphate in the wavelength range from 140 nm to 260 nm, using monochromatized synchrotron radiation from the INS‐SOR storage ring. The sample was irradiated as a thin film in vacuum. The activity of adenosine triphosphate decreased sharply below 180 nm as judged by the luminescence in the luciferin‐luciferase assay. From the exponential decay of function, the cross‐section for inactivation was calculated to be of the order of 10‐21 m2/photon in the range from 140 to 170 nm. No decrease was detected at wavelengths of 190 nm and above. The calculated quantum yield increased as the wavelength became shorter and reached to 0.20 at 150 nm. The release of adenine at 160 nm‐irradiation was detected by thin layer chromatography; no adenosine diphosphate or adenosine monophosphate occurred. Only a trace of adenine was found after 190 nm‐irradiation. These results indicate that the broad absorption peak for higher excitations attributable to the base moiety around 190 nm does not cause both structural and functional changes, while the absorption by the sugar‐phosphate group produces the rupture of N‐glycosidic bond, and probably leads to the loss of function.
PHOTOACOUSTIC SPECTRA OF SOME BIOLOGICAL MOLECULES BETWEEN 300 AND 130 nm
Authors: Inagaki Takashi , Ito Atsushi , Hieda Kotaro , Ito Takashi
Published: January 2008

Photoacoustic spectra of the biological molecules thymine, adenine, tyrosine, ergosterol and polyadenylic acid were obtained in the 300‐130 nm region of photon wavelength using synchrotron radiation as a light source. Photoacoustic measurements were performed with thin solid films of these molecules made by vacuum evaporation, except for polyadenylic acid whose thin films were made from the aqueous solution. It was found that the spectra exhibit absorption structures which are in good agreements with those found from conventional transmission measurements. Some of the spectra, however, exhibit a marked deviation from the transmission data in the region below 145 nm, which may be indicative of photon absorption with subsequent photoelectron emission.
VIRUS‐CELL INTERACTIONS AS PROBES FOR VACUUM‐ULTRAVIOLET RADIATION DAMAGE AND REPAIR
Authors: Coohill Thomas P.
Published: January 2008

Irradiation of biological materials in the vacuum‐ultraviolet (VUV*‐wavelengths below 200nm) is inhibited by the substantial absorption of water, air, and of the material itself. We have made a rough estimate of the penetration of radiation to the center of three kinds of cells and three viruses of different sizes at three wavelengths in the VUV (155 nm, 170 nm, and 200 nm) and two wavelengths in the far‐UV (220 nm and 250 nm). With the exception of bacteria, absorption limits the penetration of wavelengths below 200 nm to the center of the cell, to less than one percent of the radiation striking the cell surface. Thus, effects on the genetic material when cells larger than bacteria are irradiated with VUV should be insignificant. However, even the largest viruses were relatively transparent to all the wavelengths that we used. Therefore viruses can be considered to be model organisms for VUV studies; we list some of the maj or advantages of using them as probes to study cellular responses to VUV biological damage. The use of viral probes to study membrane phenomena also is noted since damage by VUV often is limited to cell surfaces. We suggest that the use of viruses may make possible biological experiments in the VUV that were not feasible with cells alone.
LINKED‐FUNCTION ANALYSIS OF FLUORESCENCE DECAY KINETICS: RESOLUTION OF SIDE‐CHAIN ROTAMER POPULATIONS OF A SINGLE AROMATIC AMINO ACID IN SMALL POLYPEPTIDES
Authors: Alexander Ross J. B. , Laws William R. , Sutherland John Clark , Buku Angeliki , Katsoyannis Panayotis G. , Schwartz Irving L. , Wyssbrod Herman R.
Published: January 2008

A linked‐function approach to fluorescence decay data analysis is presented that permits complex systems to be resolved from a single decay curve. The method involves linking fluorescence decay parameters based on a relationship established by independent physical measurements. As an example, by correlating the fluorescence data with 1H‐NMR results, the complex fluorescence decay kinetics of tyrosine analogs and single tyrosyl residues in simple polypeptides can be explained by ground‐state rotameric populations of the phenol ring about the Cα‐Cβ bond.
ACTION SPECTRA FOR IN ACTIVATION AND MEMBRANE DAMAGE OF Saccharomyces cerevisiae CELLS IRRADIATED IN VACUUM BY MONOCHROMATIC SYNCHROTRON UV RADIATION (155‐250 nm)
Authors: Hidea Kotaro , Ito Takashi
Published: January 2008

We investigated the wavelength dependence of inactivation and membrane damage in yeast cells (Saccharomyces cerevisiae) in the range from 170 to 200 nm. Action spectra constructed at wavelengths from 155 to 250 nm using published data were nearly the same for the two types of effects below 200 nm, but differed from the absorption spectrum of DNA, indicating that major lethal damage occurred in the membrane, not in DNA. This conclusion was strongly supported by the finding that far‐UV‐sensitive cells, which lack excision repair, showed no enhanced sensitivity below 200 nm.
ANTIVIRAL ACTIVITY OF THE PHOTOACTIVE THIOPHENE α‐TERTHIENYL
Authors: Hudson J. B. , Graham E. A. , Micki N. , Hudson L. , Towers G. H. N.
Published: January 2008

The naturally occurring thiophene, α‐terthienyl, was investigated for phototoxicity against several viruses and a line of mouse cells. The compound was extremely phototoxic to the two‐membrane‐containing animal viruses, murine cytomegalovirus (MCMV) and Sindbis virus (SV). Antiviral activity was detected at 105μg/m in the presence of UVA. However, no effect was seen in the absence of UV‐A, even at 0.1 μg/m of αT. Mouse cells were much more resistant to αT, as was the bacterial virus T4, which does not contain a membrane. Murine CMV, which had been inactivated by αT and UVA, penetrated mouse cells efficiently; but the viral DNA could not replicate, and late viral proteins were not made. Thus viral gene expression was inhibited in the photoinactivated virus. In order to account for all these data we suggest that αT may interact with viral proteins in addition to membrane lipids.
THE EFFECT OF APPLIED THICKNESS ON SUNSCREEN PROTECTION: IN VIVO AND IN VITRO STUDIES
Authors: Brown S. , Diffey B. L.
Published: January 2008

The effect of applied thickness of sunscreen on the degree of protection against ultraviolet exposure has been investigated using an in vitro model (excised human epidermis) and phototesting in human subjects. The agreement between the protection factors obtained by each technique was excellent. It is shown that the influence of applied thickness on sunscreen protection factors is much less than would be predicted by Beer's law.
A PROTON RELEASE SITE ON THE C‐TERMINAL SIDE OF BACTERIORHODOPSIN
Authors: Li Qingguo , Govindjee Rajni , Ebrey Thomas G.
Published: January 2008

We have studied the pH dependence of the light‐induced proton release and uptake by bacteriorhodopsin. The quantum efficiency of proton release in cell envelopes and proton uptake in phospholipid vesicles is high in the low pH range and begins to decline between pH 6 and 7 in cell envelopes and between pH 7–8 in phospholipid vesicles. In the cell envelope vesicles the proton release increases again above pH 8–8.5; in phospholipid vesicles a proton release is observed before proton uptake at pHs greater than 9. We suggest that the light‐induced proton release observed at high pHs are due to protons released and rebound on the carboxyl terminal side of bacteriorhodopsin.
EXCITATION ENERGY TRANSFER IN THE CRYPTOPHYTES. FLUORESCENCE EXCITATION SPECTRA AND PICOSECOND TIME‐RESOLVED EMISSION SPECTRA OF INTACT ALGAE AT 77 K
Authors: Bruce Doug , Biggins John , Steiner Tom , Thewalt Mike
Published: January 2008

Excitation spectra of chlorophyll‐a (Chl‐a) fluorescence in intact cells of Cryptomonas ovata, Chroomonas pauciplastida and Chroomonas salina were determined at 77 K. For all species the excitation spectra for emission from Chl‐a associated with photosystem II (PSII) showed increased contributions by a carotenoid (493 nm) and phycobiliproteins, and decreased contributions by carotenoid (417 nm, 505 nm) and Chl‐a (445 nm) as compared to excitation spectra for emission from Chl‐a associated with photosystem I (PSI). Excitation spectra of C. salina and C. ovata showed an increased contribution by Chl‐c2 to PSII Chl‐a fluorescence emission. In all three species the absorbance band positions of Chl‐a, as determined from the excitation spectra, were similar to those previously described in green plants. green algae and phycobilisome‐containing organisms. Time‐resolved 77 K fluorescence emission spectra of C. ovata and C. salina showed successive emission from both phycoerythrin and Chl‐c2, PSII Chl‐a, and PSI Chl‐a. C. pauciplastida showed successive emission from phycocyanin, PSII Chl‐a, and PSI Chl‐a. Spectral red‐shifts with time were observed for the phycobiliprotein peaks in all three species. The fluorescence decay of phycoerythrin in C. ovata and C. salina was faster than that of phycocyanin in C. pauciplastida. The results are discussed in relation to the organization of the antenna pigments of PSII and PSI in the cryptophyte algae.
AN UNUSUAL EXCITED STATE SPECIES OF ortho‐ HYDROXY‐CINNAMIC ACID*
Authors: Wolfbeis Otto S. , Begum Monowara , Hochmuth Petra
Published: January 2008

The fluorescence of ortho‐hydroxycinnamic acid was studied in aqueous solution over the pH 0‐14 range and in methanol. At pH values above 9.7, intense anion fluorescence is observed. In the pH 4‐9 range emissions are from both the monoanion (albeit weakly) and from the dianion due to photodissociation. In the pH 0‐4 range a blue and a green fluorescence was found, which is attributed to emissions from the unchanged molecule and from an unusual excited state tautomer respectively. The latter is assumed to be the phenolate anion of cinnamic acid and represents a tautomer with no equivalent in the electronic ground state. It is assumed to be formed by adiabatic photodissociation during the lifetime of the first excited singlet state.
FOURIER ANALYSIS OF ANGULAR DISTRIBUTIONS FOR MOTILE MICROORGANISMS
Authors: Hauder Donat‐P. , Lipson Edward D.
Published: January 2008

The method of Fourier transformation is used to analyze histograms of the angular distribution of organisms moving with respect to a stimulus, in this case the light direction. In the Fourier spectra, the components with the highest amplitudes indicate the modality of orientation, i.e. the number of preferred directions, and the corresponding phase values indicate the deviation from the light direction. In the frequency domain, those components with high amplitude and/or those with low frequencies (low‐pass filtering) can be selected and used to reconstruct a smoothed histogram by means of an inverse Fourier transform. This method reduces the noise level and reveals the prominent features of histograms. Examples of unimodal, bimodal and multimodal distributions are shown in their original and smoothed form for the flagellate Euglena gracilis, and for amoebae and pseudoplasmodia or the slime mold Dictyostelium discoideum.
SENSITIVITY OF MOUSE SKH:HR‐2 TO ULTRAVIOLET LIGHT: MOUSE PIGMENTATION MODEL
Authors: Warren Raphael
Published: January 2008

Abstract— The mouse Skh:HR‐2 has been reported to be sensitized to ultraviolet light and become pigmented. Using three independent parameters associated with pigmentation. we have examined the ability of the mouse to become pigmented. The methods utilized were spectroscopic (skin color). histological (melanocyte density and epidermal thickness), and biochemical (tyrosinase activity). Following a two‐week ultraviolet exposure, the mice were pigmented with the degree of pigment change related to the ultraviolet dose administered. Perturbations in skin color, epidermal thickness, melanocyte density, and tyrosinase activity were recorded. Mice were also examincd for their response to tyrosinc applied topically following each ultraviolet exposure. With the exccption of epidermal thickness. all the pigmentation parameters were accentuated when compared to results from ultraviolet exposure alone.
SINGLET OXYGEN GENERATION BY FUROCOUMARIN TRIPLET STATES—I. LINEAR FUROCOUMARINS (PSORALENS)
Authors: Knox C. N. , Land E. J. , Truscott T. G.
Published: January 2008

Abstract— Triplet extinction coefficients and hence singlet → triplet intersystem crossing quantum yields have been measured in benzene for a number of linear furocoumarins including pseudopsoralen, 5, 8‐dimethoxypsoralen, 4, 5′, 8‐trimethylpsoralen and 3‐carbethoxypseudopsoralen. These triplet yields were then used in conjunction with the corresponding quantum yields of singlet oxygen formation, measured in oxygenated solution, to estimate the fractions of furocoumarin triplets which when quenched by ground state oxygen produce singlet excited oxygen, similar data being obtained for psoralen, 5‐methoxypsoralen, 8‐methoxypsoralen and 3‐carbethoxypsoralen. The superoxide anion radical was not detected from these oxygen quenching reactions, nor was a contribution to the singlet oxygen yield found from furocoumarin excited singlet state quenching by oxygen. The fraction of furocoumarin‐oxygen quenching interactions leading to singlet oxygen varied between 0.13 (for 5, 8‐dimethoxypsoralen) and unity (for 3‐carbethoxypsoralen), and thus needs to be taken into account, as well as the triplet quantum yields, in assessing photobiological processes involving singlet oxygen.
THE STRUCTURAL CHANGES IN BOVINE ROD OUTER SEGMENTS IN THE PRESENCE OF ATP
Authors: Borys T. J. , Gura B. D. , Deshpande S. , Abrahamson E. W.
Published: January 2008

Abstract— We have, previously, described a light‐induced near infrared (700–850 nm) light scattering transient obtained in the presence of ATP from bovine rod outer segments suspensions in which the plasma but not the disk membranes were perforated (Uhl et al., 1979a). This transient was termed the ‘A’ signal. To elucidate its possible origin, we have analyzed their angular and wavelength dependencies. These data have been compared with osmotically controlled (non‐light) induced light scattering changes from identical control rod outer segments suspensions. It has been found that AD (the dark light scattering signal obtained in the presence of ATP) and ALS (the slow component of the actinic flash induced light scattering signal, AL) can be assigned to the swelling of the disk membranes while ALf (the fast component of this latter signal) can be attributed to the change in refractive index of the ROS caused by the hypsochromic spectral shift of photolyzed rhodopsin. The collective disk swelling associated with A, and ALS is consistent with the pumping of ions into the disk lumen by the action of a disk membrane bound ATPase.
BIOLUMINESCENCE OF ACETALDEHYDE CATALYZED BY BACTERIAL LUCIFERASE
Authors: Cho Ki Woong , Lee Hyun Jae , Shim Sang Chul
Published: January 2008

Abstract— Bioluminescence from the oxidation of acetaldehyde by bacterial luciferase of Photobacterium fischeri has been demonstrated for the first time and its efficiency has been compared with that of nonanal and other short chain aldehydes.
CHLORPROMAZINE INGESTION INHIBITS UV‐INDUCED SKIN CARCINOGENESIS
Authors: Peak Meyrick J. , Pfaff Michelle M. , Peraino Carl
Published: January 2008

Abstract Chlorpromazine (0.01% in drinking water) inhibits the induction of skin cancer by sunlamp irradiation of hairless mice. This inhibition is partially reversed by a single injection of ethyl nitrosourea at birth.
THE THEORY OF PHOTODYNAMIC THERAPY DOSIMETRY: CONSEQUENCES OF PHOTO‐DESTRUCTION OF SENSITIZER
Authors: Potter W. R. , Mang T. S. , Dougherty T. J.
Published: January 2008

Abstract Photodynamic dose is defined as the area under the curve of sensitizer level plotted as a function of light dose. This is a photochemical definition of dose. We will show that this definition is useful in predicting photobiological response. The photodestruction of sensitizer during photodynamic therapy is shown to result in an upper limit on the photodynamic dose which can be delivered by an unlimited light dose. This limit results in the opportunity to make total photodynamic dose uniform to considerable depths (one to two centimeters). The existence of thresholds for permanent tissue damage allows protection of normal tissue from the large light doses required to achieve this limiting dose deep in the tissue. Higher sensitizer levels in the tumor permit tumor destruction while the normal tissues are protected. A clinical trial to determine the proper level of injected dose necessary for these results is required.

This theory of photodynamic therapy (PDT) dosimetry is tested in the DBA‐SMT experimental mouse tumor system. Combinations of drug and light which are not reciprocal but are nearly equal by this theory are shown to give equivalent tumor control at seven days post treatment. Reciprocal combinations of drug and light fail to give equivalent results when they are selected using the theory to choose a combination where reciprocity should fail.
GENERATION OF ELECTRONICALLY EXCITED STATES IN SITU. POLYMORPHONUCLEAR LEUKOCYTES TREATED WITH PHENYLACETALDEHYDE
Authors: Nascimento Ana Lucia T. O. , Cilento Giuseppe
Published: January 2008

Abstract In polymorphonuclear leukocytes phenylacetaldehyde promotes an intracellular O2 consuming process in which myeloperoxidase participates. The reaction is accompanied by lipid peroxidation as shown by both malondialdehyde formation and biphasic light emission. The lipid peroxidation appears to be induced by intracellularly generated triplet benzaldehyde. When chlorophyll‐a is solubi‐lized in the leukocytes, biphasic emission is observed in the red, demonstrating that the excited species formed in lipid peroxidation transfer their energy to chlorophylls bound to the cell. The energy transfer process is efficient and does not occur by radiative transfer.
UNCOUPLING OF PHOTOPHOSPHORYLATION BY NITROGENOUS BASES. NO CORRELATION Ofb UNCOUPLING WITH pKb and PARTITION COEFFICIENT
Authors: Lotina‐Hennsen Blas , King Beatriz , Albores Martha , Pozas Rocío
Published: January 2008

Twenty six nitrogenous compounds were tested for uncoupling activity from water to methylviologen in spinach chloroplasts. No correlation was found between photophosphorylation and pKb or partition coefficient. Thus basic strength is not related with uncoupling phenomena, suggesting that nitrogenous bases are not protonated during uncoupling. Steric effect is also unimportant for uncoupling. New discovered uncouplers were acetamide, hexylamide and trichloroacetamide, which are all very efficient uncouplers. Acetamide accelerates electron transport and decreases ATP synthesis. However, it increases net proton uptake at low concentration, and collapses proton gradient at high concentration. 1,12 Diaminododecane is also a very efficient uncoupler'but it does not have any relationship with other diamines tested; it causes reversible shrinkage to the chloroplast, which suggests that it is not a detergent type of uncoupler.
AN ACTION SPECTRUM FOR LETHAL PHOTOSENSITIZATION OF Candida albicans BY 8‐MOP AFTER LOW‐DOSE BROAD‐BAND UV‐A IRRADIATION; AN ACTION SPECTRUM FOR 8‐MOP 4′,5′‐ MONOADDUCTS?
Authors: Baydoun Safa A. , Young Antony R.
Published: January 2008

An action spectrum was obtained for lethal photosensitization of Candida albicans that had been pre‐irradiated with a sub‐lethal low dose of broad‐band UV‐A after incubation with 8‐methoxypsoralen and then washed to remove any non‐photobound 8‐methoxypsoralen. The resultant spectrum with a peak in the 320‐335 nm region was similar to that obtained by a conventional method (single irradiation only) and also to the absorption spectrum of the 4′,5′‐monoadduct. These data support the hypothesis that the chromophore for lethal photosensitization by 8‐methoxypsoralen is the 8‐methoxypsoralen/DNA 4′,5′‐monoadduct rather than 8‐methoxypsoralen itself.
INDUCTION OF phr GENE EXPRESSION BY PYRIMIDINE DIMERS IN Escherichia coli
Authors: Ihara Makoto , Yamamoto Kazuo , Ohnishi Takeo
Published: January 2008

The photoreactivating enzyme (PRE) is concerned with mainly two kinds of light wavelength. The PRE splits UVC (254 nm)‐induced pyrimidine dimer by absorbing UVA (320–380 nm) or visible light in its chromophore. The present paper demonstrates that the phr gene expression was efficiently induced in an excision defective strain (uvrA∼) after irradiation by UVC and UVB (290‐320 nm), but not by UVA and visible light. In addition, the induced activity was significantly depressed by irradiation with UVA and visible light. Therefore we conclude that the phr gene expression can be induced by pyrimidine dimers.
DEPOSITION OF METALLIC and SEMICONDUCTING LAYERS ONTO BILAYER LIPID MEMBRANES
Authors: Kutnik Jan , Tien H. Ti
Published: January 2008

In this paper the phenomenon of inorganic substances deposited onto the bilayer lipid membrane is described. Metallic copper and semiconducting compounds such as CuS, FeS, CdS and also AgBr were deposited onto the bilayer lipid membrane. The cyclic voltammetry technique was used for determining electrochemical and photoelectrical properties of coated membranes. Considerable increase of stability and drastic changes of membrane properties were observed. Also investigated were the photoelectrical properties of bilayer lipid membrane with dispersed CdSe or AgBr particles in the absence and presence of pigments.
STATIC and TIME‐RESOLVED FLUORESCENCE OF AN AMPHIPHILIC FLAVIN IN AEROSOL OT REVERSED MICELLES
Authors: Visser Antonie J. W. G. , Vos Kees , Santema Jillert S. , Bouwstra Jan , Hoek Arie VAN
Published: January 2008

Spectral and time‐resolved fluorescence studies have been carried out on N(3)‐undecyllumi‐flavin dispersed in reversed micelles composed of the surfactant sodium di(2‐ethylhexyl) sulfosuccinate (Aerosol OT, AOT), various amounts of water andn‐heptane as continuous phase. The fluorescence spectral properties (spectral distribution, quantum efficiencies and lifetimes) as function of the water to AOT molar ratio suggest that the flavin occupies a position within the surfactant boundary layer in close contact with water. The fluorescence anisotropy exhibits biexponential decay with a short (0.3 ns) and a longer (1.6–2.4 ns) correlation time. The contribution of the short component increases with the growth of the droplet providing evidence for enhanced flexibility of the flavin in the interfacial layer.
DARK EFFECTS OF HEMATOPORPHYRIN DERIVATIVE ON LACTATE DEHYDROGENASE ACTIVITY and DISTRIBUTION IN HeLa CELLS: CYTOCHEMICAL EVALUATION
Authors: Freitas Isabel , Novarina Antonella
Published: January 2008

Abstract The effects of hematoporphyrin derivative (HpD) in the dark on the activity and subcellular location of lactate dehydrogenase (LDH) in HeLa cells are evaluated with an original quantitative cytochemical technique. The enzyme activity is visually indicated by diffuse patterns ascribed to loosely‐bound, cytoplasm‐LDH and by granular formations ascribed to tightly bound, mitochondrial‐LDH. The granular pattern has a longer formation lag than the diffuse pattern, since mitochondrial loci are less accessible to the reagents. Observations occasionally and unexpectedly found show that the percentage of cells with granular pattern is highly enhanced in suffering cells. This suggests that the mitochondrial‐LDH activity increases as a reaction to stress.

In cells that have incorporated HpD for 24 h in the dark, significant changes of LDH activity and distribution occur as many more cells with granular pattern and larger granules are seen, while the diffuse activity significantly decreases. These results point towards: (a) a binding of HpD at the cytoplasm LDH active site or close to it leading to enzyme inactivation; (b) a labilization of the mitochondrial membrane facilitating access to the inner loci by the cytochemical reagents and hence better visualization of the mitochondrial‐enzyme; and/or (c) an increased LDH activity ensuing from drug‐induced stress.
GROWTH DELAY STUDIES OF THE RESPONSE OF V‐79 MULTICELL SPHEROIDS EXPOSED TO DHE and RED LIGHT
Authors: Jeeves W. P. , Wilson B. C. , Smith P. , Ens K. , Spiegl P.
Published: January 2008

AbstractMulticell tumour spheroids (MTS) of V‐79 Chinese hamster cells have been used to study the role of a number of treatment and microenvironmental parameters in the modification of tumour response to Photodynamic Therapy (PDT) using visible light in combination with the photosensitizing compound dihematoporphyrin ether (DHE). The kinetics of DHE uptake into MTS, determined by fluorimetry of extracted porphyrins, indicate that after extended incubation (i.e. 24 h) the mean cellular DHE content in larger (˜300 μ.m and 400 u.m) MTS is significantly less than that for smaller (˜200 μm) MTS, consistent with a hypothesis that DHE uptake into the internal regions of spheroids is diffusion‐limited. The response of spheroids to PDT, as assessed by the endpoint of growth delay, indicates that the kinetics of spheroid volume alteration and cell loss, as well as the potential for regfrrwth, are markedly dependent on both the drug and light exposure levels used. The oxygen dependence of this response has been investigated after light irradiation of spheroid cultures equilibrated with either 21% O2(i.e. air) or 0% 02(i.e. N2). While treatment in air results in significant growth delay, the growth kinetics of DHE‐treated spheroids irradiated under N2were essentially unchanged from those of untreated spheroids. These observations clearly demonstrate an important role for oxygen, at the time of irradiation, in determining the response of spheroids to PDT.
NEUROTOXICITY OF TETRAPHENYLPORPHINESULFONATE TPPS4 and ITS RELATION TO PHOTODYNAMIC THERAPY*
Authors: Winkelman James W. , Collins George H.
Published: January 2008

Abstract Tetraphenylporphinesulfonate (TPPS4) is a synthetic porphyrin that localizes in certain tumors to a higher absolute concentration and with more favorable tumor to other tissue ratios than any other porphyrin yet studied. Its utilization for photodynamic therapy and other applications has been inhibited by reported neurotoxicity. We injected TPPS4 over a broad dose range of 5‐150 mg kg−1 and observed the effects on peripheral nerve in groups of animals sacrificed 35, 70 and 140 days later. No immediate deaths or phototoxic manifestations were seen. Light and electron microscopy, however, revealed cytoskeletal abnormalities and nerve fiber degeneration affecting both myelinated and unmyelinated fibers in all the time and dose groups. These findings have similarities to those of other experimental toxic neuropathies, and may also be related to the preponderance of autonomic manifestations in patients with porphyric neuropathy. The morphological changes consisted of tangles of fibrillar material in the myelinated fibers and loss of neurotubules in the unmyelinated fibers. Our studies indicate a direct interaction of TPPS4 with tubulin. This biological mechanism may be involved in the selective distribution of certain parenterally administered porphyrins.
A TEST OF DIFFERENT PHOTOSENSITIZERS FOR PHOTODYNAMIC TREATMENT OF CANCER IN A MURINE TUMOR MODEL
Authors: Evensen Jan Folkvard , Moan Johan
Published: January 2008

Abstract The efficiency of different sensitizers for photodynamic therapy (PDT) was tested using a model system with a C3H mammary carcinoma growing subcutaneously on the dorsal side of mouse feet. Growth curves were constructed from which growth delay and doubling time in the regrowth phase were calculated. As PDT induced oedema in the mouse foot, this model system also allowed assessment of normal tissue response.

The following sensitizers were tested: hematoporphyrin derivative (HpD), Photofrin II (PII), tetraphenylporphinetetrasulfonate (TPPS4), acridine orange (AO), phthalocyanine tetrasulfonate (PCTS), Al‐ and Zn‐phthalocyanine tetrasulfonate (A1PCTS and ZnPCTS). For tumor control, the following sensitizer efficiencies were found: PII > HpD > AIPCTS > TPPS4 >>> ZnPCTS, PCTS, AO. With regard to sensitizing normal‐tissue damage: PII > AIPCTS, TPPS4 > HpD, ZnPCTS, PCTS. The results suggest that AIPCTS should be further evaluated for use in PDT.
POTENTIOMETRIC and LASER FLASH PHOTOLYSIS STUDIES OF THE pH DEPENDENCE OF HYDROGEN PEROXIDE PRODUCTION BY THE SEMICARBAZIDE/LUMIFLAVIN/OXYGEN PHOTOSYSTEM
Authors: Navarro José A. , Roncel Mercedes , Rosa Miguel A. De la
Published: January 2008

The effect of pH on hydrogen peroxide photoproduction by the semicarbazide/lumiflavin/ oxygen system has been investigated by using the potentiometric and laser flash photolysis techniques. Kinetic analysis of (a) primary and secondary reactions involved in the photoreduction of lumiflavin and (b) lumiflavin reoxidation by oxygen have been carried out at varying pH values, drastic differences being observed in the pH dependence of both types of reactions. The reaction mechanism appears to proceed by semicarbazide‐quenching (reductive type) of the light‐excited lumiflavin in its triplet state followed, depending on pH, either by reoxidation of the so formed flavosemiquinone by molecular oxygen or by flavosemiquinone disproportionation into oxidized and fully reduced lumiflavin.
A SURVEY OF PHOTOPRODUCTS OF AN IRRADIATED OLIGODEOXYNUCLEOTIDE BY MONOCHROMATIC PHOTONS WITH THE ENERGY RANGED FROM 6.5 TO 22.5 eV
Authors: Ito Takashi , Saito Mikio , Taniguchi Taketoshi
Published: January 2008

We have irradiated 2′‐deoxyadenylyl‐(3′‐5′)‐2′‐deoxyadenosine (dephospho(dA)2) in solid state with a newly developed synchrotron irradiation system over 6.5 to 22.5 eV photon energy range (190 to 55 nm in wavelength). Densitometric analysis of thin‐layer chromatogram of photoproducts indicated that adenine and deoxyadenosine monophosphate were commonly produced above 7.3 eV (170 nm) in approximately equal amount. Deoxyribose was not detected by the fluorescence method with scratched materials from the chromatogram at any location except deoxyadenosine monophosphate and parent oligonucleotide positions. The photoproducts above mentioned were not observed at 6.5 eV (190 nm) even after very high radiation fluence. The energy dependence of this degradation indicates that the shorter the wavelength in use the smaller the fluence it requires. Careful examination of irradiated oligonucleotide on the chromatograms shows that the major portion of deoxyadenosine monophosphate so produced was the 5′phospho derivative. This site‐selective degradation, independent of photon energy, seemed to be a remarkable characteristic of vacuum‐UV induced effects above 7 eV. From these results a working hypothesis was advanced that the deoxypentose moiety was first destroyed in one of the nucleoside residues due to the strong absorption in the sugar‐phosphate group, liberating adenine on the one hand and leaving 5′‐deoxyadenosine monophosphate on the other hand.
SINGLET OXYGEN GENERATION BY FUROCOUMARINS: EFFECT OF DNA AND LIPOSOMES
Authors: Blan Quaseem A. , Grossweiner Leonard I.
Published: January 2008

The quantum yield of singlet oxygen generation by aqueous furocoumarins was measured at 365 nm using the photosensitized inactivation of subtilisin Carlsberg as the probe with the following results: psoralen (0.18), 5‐methoxypsoralen (0.013), and 8‐methoxypsoralen (0.035). Singlet oxygen formation was significant for dark complexes of 8‐MOP with calf thymus DNA and the covalent DNA photoadducts. Incorporation of 8‐MOP in sonicated egg phosphatidylcholine liposomes did not inhibit photosensitization of subtilisin Carlsberg and also led to lipid peroxidation, with positive tests for the involvement of singlet oxygen. Peroxidation of the liposomes was inhibited by the presence of α‐tocopherol and promoted by the presence of cholesterol in the membranes.
THERMAL‐LENSING AND PHOSPHORESCENCE STUDIES OF THE QUANTUM YIELD AND LIFETIME OF SINGLET MOLECULAR OXYGEN (1Δg) SENSITIZED BY HEMATOPORPHYRIN AND RELATED PORPHYRINS IN DEUTERATED AND NON‐DEUTERATED ETHANOLS
Authors: Redmond Robert W. , Heihoff Klaus , Braslavsky Silvia E. , Truscott T. George
Published: January 2008

Time‐resolved thermal‐lensing was used to measure the absolute quantum yield (φΔ) of singlet molecular oxygen, O2(1Δg), produced by hematoporphyrin photosensitization in ethanol. Deuteration of the solvent did not affect the value of φΔ. The value of φΔ= 0.53 was then used as reference to evaluate φΔ in O2 (1Δg) phosphorescence experiments with the related porphyrins, monohydroxyethylvinyl deuteroporphyrin and dihematoporphyrin ether. The φΔ values, in conjunction with the respective quantum yields of intersystem crossing (measured using a nanosecond laser flash photolysis technique) served to evaluate efficiencies, SΔ, of O2 (1Δg) production from the porphyrin triplet states. The lifetime TΔ in monodeuterated ethanol was measured as 29 ± 3 μs and 30 ± 1 (xs by time‐resolved thermal lensing and phosphorescence detection, respectively. TΔ in ethanol and fully deuterated ethanol were in good agreement with values reported in the literature.
A COMPARISON OF MAMMALIAN CELL SENSITIVITY TO EITHER 254 nm OR ARTIFICIAL “SOLAR” SIMULATED RADIATION
Authors: Gill Randall F. , Coohill Thomas P.
Published: January 2008

The sensitivity of six mammalian cell strains to either germicidal (254 nm) or artificial “solar” simulated radiation was tested. The solar simulator used had an output similar, in some respects, to natural sunlight. Cellular capacity for Herpes simplex virus production was used as the assay procedure. The tested cells were a strain of African green monkey kidney cells and five human skin fibroblast cell strains. The latter included a “normal” cell strain, and four photosensitive cell strains; three of which were strains of xeroderma pigmentosum cells, and one strain of Bloom's syndrome cells. When comparing the D10 values, the different cell strains varied by a factor of six in response to germicidal radiation, but only by a factor of two to artificial “solar” simulated radiation. The relative sensitivity of the cells to either type of radiation also varied from 1.7 to 10.9. Large variations in response occurred even among the xeroderma pigmentosum cell strains. These responses suggest that mammalian cell sensitivity to 254 nm radiation may not be a true indicator of a cell's responses to natural sunlight.
TWO WATER‐SOLUBLE FLUORESCENCE PROBES FOR CHEMIEXCITATION STUDIES: SODIUM 9,10‐DIBROMO‐ AND 9, 10‐DIPHENYLANTHRACENE‐2‐SULFONATE. SYNTHESIS, PROPERTIES AND APPLICATION TO TRIPLET ACETONE AND TETRAMETHYLDIOXETANE
Authors: Catalani Luiz H. , Wilson Thérèse , Bechara Etelvino J. H.
Published: January 2008

The syntheses of sodium 9,10‐dibromo‐ and 9,10‐diphenylanthracene‐2‐sulfonate (DBAS and DPAS, respectively) are described and their photophysical properties determined. These two probes were used in aqueous solution studies of the kinetic parameters of tetramethyldioxetane thermolysis, which were found to be the same as in organic solvents. The yields of triplet and singlet acetone generated by the decomposition of this dioxetane in water are also comparable to the literature values in organic medium. The lifetime of triplet acetone in water was determined to be 13 ± 2 u.s by a method based on the measurement of the fluorescence decay of DBAS excited via energy transfer from triplet acetone, by the time‐correlated single‐photon counting technique. Sorbate ion quenches triplet acetone from tetramethyldioxetane with a rate constant smaller but close to the diffusion‐controlled limit.
ULTRAVIOLET QUANTUM YIELDS OF PHOTOPHOSPHORYLATION IN Halobacterium halobium*
Authors: Wagner Gottfried , Traulich Bernhard , Hartmann Karl M.
Published: January 2008

Quantum yields of photophosphorylation in Halobacterium halobium were determined for ultraviolet spectral bands between 276 and 365 nm, and at 565 nm wavelength, based on integral spectral cell absorptance, bacteriorhodopsin‐specific cell absorptance and the corresponding quantum dose rates. In the ultraviolet, there is an almost linear decline of the quantum yields of photophosphorylation from 365 to 276 nm wavelength, despite the peak absorption of bacteriorhodopsin at 280 nm. The cycling quantum yield for 276 nm excitation of bacteriorhodopsin was determined as 4.5 ± 1.8%, which is about one fourth of the value of 19% for solubilized bacteriorhodopsin. Threshold energy fluence rates of 20 W m−2 for UV‐B radiation typify the photophosphorylation as three orders less sensitive than the sensory UV‐B avoidance response that needs 0.02 W m−2 as the threshold. Thus, UV‐B avoidance appears as the dominating strategy for survival of the archaic bacterium H. halobium, rather than possible photoenergetic use of UV‐B radiation and photorepair of UV‐damage.