bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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

AbstractThe 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

AbstractWe 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.
TOWARD THE LINK BETWEEN MEMBRANES TRANSPORT AND PHOTOPERCEPTION IN PLANT
Authors: Blatt Michael R. 
Published: January 2008

“The processes of growth and morphogenesis represent the movements of chemical groups. atcertain rates and in certain definite directions in space. within the organism. Thus, growth andmorphogenesis represent transport processes which, in common with the more popular membrane transport, must be described by vector quantities, having both magnitude and direction in space.
ENERGY CONVERSION IN THE DECAY OF TRIPLET LUMIFLAVIN IN THE PRESENCE OF FERRI‐ AND FERROCYANIDE
Authors: Naman S. A. 
Published: January 2008

Abstract—Flash photolysis at 450 nm has been used to study the quenching of the excited triplet state of lumiflavin and the transient species formed in subsequent reactions in deaerated phosphate buffer (pH 6.9).The effect of the presence of ferricyanide on the life time of triplet lumiflavin has been studied. The results suggest an energy transfer reaction without concurrent electron transfer reactions. The rate constant for the process was 2.8 times 109M‐1s‐1. The analogous reaction with ferrocyanide could not be observed because of the efficient electron transfer reaction (δG = ‐20.6 kcal mol‐1) leading to the formation of the semireduced lumiflavin and ferricyanide. The rate constant for this reaction was 3.3 times 109M‐1s‐1. The semireduced lumiflavin radical was found to disappear in a second order reaction with a rate constant of 1.7 times 109M‐1s‐1. It was found to react with ferricyanide with a rate constant of 0.7 times 109M‐1s‐1.A model for the various photochemical and photophysical processes involved in the decay and quenching of the lumiflavin triplet state is suggested and discussed.
SPECTROSCOPIC INVESTIGATION OF DIHYDRONICOTINAMIDES‐I: CONFORMATION, ABSORPTION, AND FLUORESCENCE
Authors: FISCHER PETER , FLECKENSTEIN JURGEN , HöNES JOACHIM 
Published: January 2008

Abstract— The 1(N)‐(2,6‐dichlorobenzyl)‐1,4‐dihydronicotinamide (I), N‐methyl‐ and N,N‐dimethyl‐1(N)‐(2,6‐dichlorobenzyl)‐1,4‐dihydronicotinamide (II and III), respectively), and 1(N)‐(2,6‐dichloro‐benzyl)‐2‐aminomethyl‐1,4‐dihydronicotinic acid lactame (IV) were synthesized as model compounds for natural coenzymes, and systematically studied by 1H NMR, UV/V1S absorption and fluorescence spectroscopy. The absorption at ∼ 340 nm argues for an effective conjugation between dihydropyridine and carboxamide π‐system, and rules out any severely twisted conformation. For the natural coenzymes NADH and NMNH, as well as for I and II (with no or only one N‐amide substituent), 1H NMR definitively establishes a transoid conformation in solution, with the carbonyl O close to 2‐H of the dihydropyridine ring. N,N‐dimethyl substitution effectively inverts the carboxamide orientation into the cisoid form. The 1H NMR data (as well as molar extinctions) for the fused‐ring derivatives IV and V, with a fixed cisoid and transoid structure, respectively, provide final proof for the conformational assignment.Absorption maxima are shifted to lower energies with increasing solvent polarity. In solvents which can act as hydrogen bond acceptors to the carboxamide N‐H, absorption shows a general blue‐shift of ∼ 10 nm. H‐bond donor solvents do not affect absorption maxima but enhance molar extinction. Fluorescence maxima show a similar dependence on solvent polarity but no specific hydrogen‐bonding effect. Fluorescence quantum yields appear increased tenfold in solvents donating H‐bonds to the carboxamide C=O group. These results are interpreted in terms of the vinylogous amide resonance between C=O function and ring‐N lone pair being the electronic interaction dominating in the ground state of dihydronicotinamides.
A ROLE FOR MENADIONE IN THE PURPLE MEMBRANE PROTON PUMP?
Authors: Renthal Robert , Hollub Alexander 
Published: January 2008

Abstract— It has been assumed that proton pumps such as purple membrane lack redox loops. However, purple membrane does contain an electron carrier. Kates et al. (Meth. Enzymol. 88,98–1 111, 1982) reported the presence of 1 mole of vitaminMK–8 to 6 mol of bacteriorhodopsin among the nonpolar lipids. Is this quinone functionally important in the proton pump mechanism?Proton pumping rates were measured with lipid‐free bacteriorhodopsin reconstituted in vesicles to which varying amounts of vitamin K1 were added. With soybean lipids, in the presence of tetraphenyl boron, the pump quantum yield was 0.04H+/photon. This result was independent of the amount of vitamin K, added over a range of 0 to a 100‐fold mole ratio to bacteriorhodopsin. A similar result was obtained with H. halobium lipids. The pump quantum yield in vesicles is much less than reported for membrane sheets and whole cells. The results support the conclusion that a vitamin K Q‐cycle is not involved in the purple membrane proton pump.
8‐METHOXYPSORALEN‐PHOTOINDUCED DNA CROSSLINKS AS DETERMINED IN YEAST BY ALKALINE STEP ELUTION UNDER DIFFERENT REIRRADIATION CONDITIONS. RELATION WITH GENETIC EFFECTS
Authors: Cundari E. , Averbeck D. 
Published: January 2008

Abstract—DNA damage induced by 8‐methoxypsoralen (8‐MOP) plus near UV light (UVA) was analyzed in diploid yeast using the alkaline step elution technique. The presence of 8‐MOP and UVA induced DNA interstrand cross‐links was revealed by the increase of DNA retained on elution filters as compared to untreated controls. The fraction of DNA retained on filters increased linearly with UVA dose. The amount of cross‐links was estimated from the fraction of DNA retained on filters using a dose of &#x006d;̀‐radiation leading to a number of DNA strand breaks at least equivalent to the number of 8‐MOP induced photoadducts.When 8‐MOP treated cells were exposed to monochromatic light, 365 nm light induced monoadducts and cross‐links whereas 405 nm light induced only monoadducts. When submitting 8‐MOP plus 405 nm light treated cells to 365 nm irradiation, after removal of unbound 8‐MOP by washing, a portion of 8‐MOP plus 405 nm light induced monoadducts was converted into cross‐links. The amount of monoadducts transformed into cross‐links was dependent on the dose of 365 nm irradiation up to a maximum likely to correspond to the number of suitably positioned furan‐side monoadducts that could be converted into biadducts. When 8‐MOP plus 365 nm light treated cells were reirradiated with 365 nm light, following the same protocol, the maximum level of cross‐linking obtainable in yeast was lower than that obtained with 8‐MOP in a 405 nm plus 365 nm reirradiation protocol.In the presence of 8‐MOP single exposures to 405 nm light were found to be only slightly genotoxic. However, when followed by second exposures to 365 nm light, a dose‐dependent increase in genetic effects, i.e. mutation and gene conversion, was observed in parallel to the induction of DNA crosslinks. These results stress again the prominent role of DNA cross‐links in the genotoxicity of 8‐MOP.
TEMPERATURE AND MYCOCHROME SYSTEM IN NEAR‐UV LIGHT INDUCIBLE AND BLUE LIGHT REVERSIBLE PHOTOINDUCTION OF CONIDIATION IN Alternaria tomato*
Authors: Kumagai Tadashi 
Published: January 2008

Abstract— When dark‐grown colonies were exposed to near‐UV light, conidiophore formation was induced, and conidia developed during a subsequent dark period. Simultaneous exposure to near‐UV and blue light inhibited induction of conidiation. The inductive effect of near‐UV light irradiation was greatly enhanced by treating colonies with low temperatures for 4 h during the 2nd‐6th hour of incubation in the dark following inductive irradiation: the enhancement was greatest at 21°C. The extent of inhibition by blue light increased with the temperature between 10 and 28°C. This diminution by low temperature was greatest when colonies previously kept at a low temperature were exposed to inductive irradiation: the longer the duration between inductive irradiation and temperature treatment, the lower the diminution. Higher fluences of blue light were required to suppress conidial induction at lower temperature.Thus, it is evident that the inductive effect of near‐UV light irradiation on conidiation and the suppressive effect of blue light irradiation are each responsive to different temperatures applied at different times.
MECHANISM OF PHOTOSENSITIZATION BY PHEOPHORBIDE a STUDIED BY PHOTOHEMOLYSIS OF ERYTHROCYTES AND ELECTRON spIN RESONANCE SPECTROSCOPY
Authors: KUWABARA M. , YAMAMOTO T. , INANAM O. , SATO F. 
Published: January 2008

Abstract Phcophorbide a (PPa), a causal substance of food intoxication, when excited by exposure to light wavelengths of over 600 nm, caused the photohemolysis of goat erythrocytes in proportion to the incubation time of the cells. The addition of N‐3, an effective scavenger of 1O2, to the medium markedly inhibited the hemolysis of erythrocytes in a concentration‐dependent manner, whereas the addition of superoxide dismutase (SOD) and catalase, inhibitors of O‐2 and H2O2 generation, respectively, to the medium had little effect on it.Methods for converting 1O2 to a nitroxide radical by 2,2,6,6‐tetramethyl‐4‐piperidone (TMPD) and for trapping O‐2 and OH by 5,5‐dimethyl‐l‐pyrroline‐A'‐oxide (DMPO) were employed to observe directly these activated oxygens by electron spin resonance (ESR). The methods provided evidence that only 1O2, was produced by PPa, which was excited by light wavelengths of over 600 nm. Both the addition of N3 to the solution and the removal of oxygen from the solution inhibited the generation of 1O2.These results led us to conclude that 1O2 was mainly responsible for the hemolysis of erythrocytes by photoexcited PPa.
α‐OXIDASE ACTIVITY IN PLANTS AS PROMOTOR OF ELECTRONIC ENERGY
Authors: CAMPA ANA , SALIM‐HANNA MARTA , CILENTO GIUSEPPE 
Published: January 2008

Abstract The a‐oxidase activity of higher plants acting on long chain fatty acids generates the lower aldehyde in the ground state; however if chlorophyll or chioroplasts are present the chlorophylls are excited most likely by a chemically initiated electron exchange (CIEEL) luminescence process with the putative a‐peroxylactone intermediate. When the aldehyde is substituted for the acid, the lower aldehyde appears in the triplet state. The chiral discrimination observed in the quenching by D‐ and L‐tryptophan of the chlorophyll sensitized emission indicates that the triplet aldehyde is generated within the enzymatic preparation and transfers energy while still bound to the enzyme.Chlorophylls in chioroplasts are excited by addition of a long chain fatty acid or aldehyde. The mechanism, however, is unknown.
PICOSECOND FLUORESCENCE OF R3230AC MAMMARY CARCINOMA MITOCHONDRIA AFTER TREATMENT WITH HEMATOPORPHYRIN DERIVATIVE and PHOTOFRIN®II in vivo
Authors: Hanzlik Cheryl A. , Knox Robert S. , Gibson Scott L. , Hilf Russell 
Published: January 2008

Abstract—Hematoporphyrin derivative(HPD) and other porphyrin samples were excited by 20‐ps 532‐nm laser pulses. Fluorescence was detected using a low‐jitter streak camera. Data were fitted to a sum of exponential decay times on the order of picoseconds. Fluorescence of porphyrins in aqueous solution show various behaviors depending on the hydrophobicity of the porphyrins. The most hydrophilic porphyrins show long decays only(500 ps). Porphyrins intermediate in hydrophobicity have intensity‐dependent fast decays. The most hydrophobic have fast decays (< 20 ps). Picosecond fluorescences of mitochondria prepared from rat tumors treatedin vivowith HPD or Photofrin II show an increase in the ratio of fast to slow decays when compared to the injected porphyrins. These results are consistent with the concentration of the more hydrophobic porphyrins in mitochondria in photosensitization treatment. Thus picosecond fluorescence studies of porphyrins may provide a means to obtain photoproperties which differentiate between effective and ineffectivein vivophotosensitizers.
FLUENCE‐RESPONSE RELATIONSHIP FOR PHOTOGENE EXPRESSION IN ETIOLATED PEA SEEDLINGS†
Authors: Yoshida Kazuichi , Takimoto Atsushi , Sasaki Yukiko 
Published: January 2008

Abstract—Fluence‐response relationships in transcript accumulation were investigated at various wavelengths for the following photogenes: the nuclear‐encoded small subunit gene of ribulose bisphosphate carboxylase/oxygenase (rbcS), the nuclear‐encoded chlorophyll alb‐binding protein gene (Cab), the chloroplast‐encoded large subunit gene of ribulose bisphosphate carboxylase/oxygenase (rbch) and the chloroplast‐encoded photosystem I A2 subunit gene (psaB). The fluence‐response curves for all genes obtained at all wavelengths showed a biphasic character suggesting the involvement of both very low fluence response and low fluence response mediated by phytochrome. The proportion responding in the very low fluence range differed with the gene, and was largest for rbcL followed by psaB, Cab and rbcS in this order.
DISTRIBUTION AND ELIMINATION OF PHOTOFRIN II IN MICE
Authors: Bellnier David A. , Ho Yau‐Kwan , Pandey Ravindra K. , Missert Joseph R. , Dougherty Thomas J. 
Published: January 2008

Abstract—The distribution and elimination of [14C]PH, the radioisotopically‐labeled equivalent of the mixture of porphyrins known as Photofrin II used in the photodynamic treatment of solid tumors, were determined in tumor‐free and SMT‐F tumor‐bearing DBA/2 Ha‐DD mice. Following i.p. injection, drug was absorbed from the peritoneum with a half‐life of about 1 h; elimination from plasma was rapid, declining about 1.4 logs in concentration over 48 h following i.v. administration. However, some [14C]‐activity was still detectable after 75 days. Normal tissues take up the drug within about 7.5 h after administration, with peak concentrations distributed as follows: liver, adrenal gland, urinary bladder > pancreas, kidney, spleen > stomach, bone, lung, heart > muscle > brain. Only skeletal muscle, brain, and skin located contralaterally to subcutaneously implanted SMT‐F tumors had peak [14C]‐activities lower than tumor tissue; skin overlying SMT‐F tumors showed concentrations not significantly different (P > 0.3) from tumor. After 75 days all tissues examined retained some fraction of [14C]‐activity, ranging from 16% for kidney to 61% for spleen, of the initial peak tissue levels. The primary route of elimination of Photofrin II was through the bile‐gut pathway, with greater than 59% of the administered [14C]‐activity recovered in the feces, and only about 6% in the urine, over 192 h. HPLC analyses of fecal extracts showed that mostly monomeric and other low molecular weight porphyrin components of Photofrin II were eliminated. The higher molecular weight oligomeric fractions of Photofrin II were retained in liver and spleen up to 14 days after injection.
INACTIVATION AND MUTAGENESIS OF Herpes VIRUS BY PHOTODYNAMIC TREATMENT WITH THERAPEUTIC DYES
Authors: Lytle C.D. , Carney P.G. , Felten R.P. , Bushar H.F. , Straight R.C. 
Published: January 2008

Abstract—Dyes which photosensitize membranes may be clinically useful for photodynamic treatment (PDT) of Herpes simplex virus (HSV) infections. It is important to determine whether the enveloped HSV can be inactivated via membrane damage without affecting the genetic material. Selection of appropriate PDT conditions, including the choice of dye, could minimize viral mutagenesis. We determined the mutagenesis caused by PDT employing three membrane‐photosensitizing dyes of potential use in cancer photochemotherapy (Photofrin II, polyhematoporphyrin esters, zinc phthalocy‐anine tetrasulfonates) and a DNA‐photosensitizing dye (proflavine sulfate). The effects were compared to those caused by exposure of HSV to ultraviolet radiation(UV). The procedure consisted of incubating HSV with µ,g/ml (µM) concentrations of the dye, irradiating the samples with broad spectrum visible/near‐UV radition (Daylight fluorescent lamps) and assaying the survival of the treated HSV. Zinc phthalocyanine was the most potent dye per absorbed photon for inactivating HSV. In parallel with determination of survival, progeny of the surviving virus were grown for determination of mutagenesis. The progeny virus was harvested and subsequently assayed in the presence and absence of 40 µ,g/ml iododeoxycytidine (ICrd) to determine the frequency of mutation to ICrd resistance. Mutation frequencies were determined for progeny from the 1–4% survival level. For PDT with each membrane‐photosensitizing dye, only zinc phthalocyanine increased the mutation frequency over the untreated control. This increase was <2‐fold. Proflavine increased the mutation frequency 2–3 fold over the untreated control. Ultraviolet produced a 15–20 fold increase over the untreated control. Therefore, all four dyes were much less mutagenic than UV at the same toxicity level (P<0.0001), and the membrane‐photosensitizing dyes were less mutagenic than the DNA‐photosensitizing proflavine at the same toxicity level (P<.0001).
ULTRAVIOLET ACTION SPECTRA (280 to 380 nm) AND SOLAR EFFECTIVENESS SPECTRA FOR HIGHER PLANTS
Authors: Coohill Thomas P. 
Published: January 2008

AbstractSeveral ultraviolet (UV) action spectra that typify the responses of higher plants to irradiation by wavelengths between 280 nm and 380 nm are shown. An attempt is made to generate common spectra that may be used, at least temporarily, to represent the effects of UV on such important biological parameters as photosynthesis. The goal is to provide an estimate of plant response to solar UV and to the potential increase in ground level UV postulated for a depleted stratospheric ozone layer. Solar plant damage effectiveness curves are generated under “normal” solar UV conditions, and under an assumed UV increase corresponding to a 16% depletion in total ozone. Additional effects due to ozone depletion are concentrated in the UV‐B region, especially at wavelengths between about 297 nm and 315 nm. Common features of these effectiveness curves are noted, and limitations are pointed out. As expected, no common spectrum has been found that can substitute for any specific spectrum nor that is unique enough to provide more than a limited first approximation of a plant damage spectrum. Additional information must be generated to fulfill this need.