bluuebunny/crossref_metadata_2025_split huggingface dataset:
PHOTOINACTIVATION OF INFLUENZA VIRUS FUSION AND INFECTIVITY BY ROSE BENGAL
Authors: Lenard John , Vanderoef Roger 
Published: January 2008

AbstractRose bengal inactivated influenza virus upon exposure to light. Infectivity and fusion were inactivated with the same dose dependence, supporting the suggestion that the virucidal activity of photodynamic agents against enveloped viruses may be generally due to inactivation of their fusion protein(s). Concentrations required for inac‐ti vation were found to depend upon the ratio of rose bengal to virus, rather than on the nominal aqueous concentration. Fusion‐competent virosomes were inactivated similarly to intact virus particles. The HAZ portion of the influenza fusion protein HA underwent two different, apparently mutually exclusive modifications upon illumination with rose bengal: cross‐linking, and conversion to a form that moved slightly more slowly on sodium dodecyl sulfate poly‐acrylamide gel electrophoresis. Inactivation of viral fusion was inhibited by oxygen removal or addition of azide or β‐carotene, and was enhanced by D2O, consistent with partial involvement of singlet oxygen. The possibility of a second mechanism of viral photoinactivation, by direct interaction between the viral fusion protein and the pho‐toactivated dye, is also discussed.
THE EFFECT OF DIFFERENTIATION ON PHOTOSENSITIZER UPTAKE BY HL60 CELLS
Authors: Korbelik Mladen , Krosl Gorazd , Adomat Hans , Skov Kristen A. 
Published: January 2008

AbstractThe capability of human promyelocytic leukemia cells HL60 to be induced to differentiate to various stages along the monocytic or myelocytic pathway was exploited for investigation of the uptake of selected photo‐sensitizers by diverse types of cells of the same origin. The results showed that there was no substantial difference in photofrin uptake between noninduced HL60 cells, immature monocytes, immature neutrophils and cells differentiated along the eosinophilic pathway. In contrast, HL60 cells differentiated into macrophages (HL609) exhibited markedly increased photofrin uptake, which was further enhanced by their pretreatment with bacterial lipopolysaccharide. Similar results were obtained with other photosensitizers tested: di‐and tetrasulfonated aluminum phthalocyanines (AIPcS2 and AIPcS4), tetrasulfonated zinc phthalocyanine (ZnPcS4), tetraphenylporphine tetrasulfonate (TPPS4) and benzoporphyrin derivative monoacid (BPD). Despite marked differences in the state of self‐aggregation and other chemical properties of these compounds, the degree of their preferential uptake by HL60 PH cells showed very little variation. In a typical experiment, the uptake of these photosensitizers by HL60 PH cells was four to five times higher than the uptake by noninduced HL60 cells. In addition to the fluorometric assay employed in most of the experiments, cellular concentration of AlPcS4 was determined by measurement of elementary aluminum using atomic absorption spectroscopy.
ISOLATION OF MUTANTS OF THE FUNGUS Cercospora nicotianae ALTERED IN THEIR RESPONSE TO SINGLET‐OXYGEN‐GENERATING PHOTOSENSITIZERS
Authors: Jenns Anne E. , Scott Donna L. , Bowden Edmond F. , Daub Margaret E. 
Published: January 2008

AbstractFungi in the genus Cercospora produce a singlet‐oxygen‐generating photosensitizing toxin cercosporin, which plays an important role in the ability of these fungi to parasitize plants. Previous studies demonstrated that resistance to cercosporin was associated with the ability of the fungus to reduce and detoxify cercosporin transiently. In order to characterize the mechanism of cercosporin resistance further, two types of mutants were isolated. One set of mutants was selected directly for sensitivity to cercosporin. Six cercosporin‐sensitive mutants were isolated. Five of the mutants were totally inhibited by cercosporin as well as by five other photosensitizers, methylene blue, toluidine blue, eosin Y, rose bengal and hematoporphyrin. These five mutants were also deficient in cercosporin‐reducing ability. The sixth cercosporin‐sensitive mutant was only partially inhibited by cercosporin. This mutant was unaltered in cercosporin‐reducing ability and in its response to the other photosensitizers. In order to test hypotheses concerning the mechanism of cercosporin reduction, a second set of mutants was selected for general deficiency in cell surface‐reducing capability by screening for the inability to reduce two tetrazolium dyes (p‐tolyltetrazolium red and 2,3,5‐triphenyltetrazolium chloride) of similar redox potential to cercosporin. Dye‐reduction‐deficient mutants were unaltered in their resistance to cercosporin and in cercosporin‐reducing ability. We conclude that cercosporin resistance of these fungi is strongly correlated with the ability to reduce cercosporin. However, cercosporin‐reducing ability is separable from the general ability to reduce external electron acceptors.
LOCAL NEUROTOXICITY OF HEMATOPORPHYRIN DERIVATIVE FOLLOWING INTRACEREBRAL INJECTION
Authors: Noske David P. , Kamphorst Wouter , Wolbers John G. , Sterenborg Henricus J. C. M. 
Published: January 2008

AbstractThe present study reports on toxicity of hematoporphyrin derivative (HpD) for normal brain tissue in vivo without the addition of light. Hematoporphyrin derivative was injected by slow infusion in rat brains. Histological examination was carried out for intervals after HpD administration, ranging from 0 h to 15 days. Ultrastructural changes were examinated with transmission electron microscopy. The extent of the necrosis was determined for different HpD concentrations and compared with control animals infused with 0.9% saline. Leukocytic infiltration was observed at day 5. Transmission electron microscopy showed that nuclei of neurons were completely disintegrated 4 h after HpD administration. Furthermore disruption of myelin sheaths was observed. The extent of the necrosis decreased with lower HpD doses. Injection of 2 μg HpD in a volume of 4 μL (0.5 mg/mL) resulted in a virtually equal extension of the tissue damage, as compared to the mechanical damage in the control animals caused by the infusion procedure.
ON THE SOURCE OF THE OSCILLATIONS OBSERVED DURING in vivo ZINC PHTHALOCYANINE FLUORESCENCE PHARMACOKINETIC MEASUREMENTS IN MICE
Authors: Dickson Eva F. Gudgin , Holmes Hugh , Jori Giulio , Kennedy James C. , Nadeau Pierre , Pottier Roy H. , Rossi Francesca , Russell David A. , Weagle Glenn E. 
Published: January 2008

AbstractSurface‐detected fluorescence spectroscopy can be used to monitor the pharmacokinetics of uptake and clearance of red‐absorbing fluorophores such as zinc(II) phthalocyanine (ZnPc) in vivo. When this technique is applied to mice that have been fed on a normal chlorophyll‐based diet, and particularly when measurements are performed in the abdominal region, oscillations are sometimes observed superimposed on the pharmacokinetic curve of the ZnPc. An oscillatory signal has also been observed arising from the abdominal region of control mice fed a normal diet but not injected with the ZnPc photosensitizer; this oscillatory component to the signal is reduced when mice are fed a chlorophyll‐free diet. The oscillatory signal component has been attributed to fluorescence arising from chlorophyll derivatives (pheophorbide/pheophytin) contained in the rodent food, whose concentration in the measured abdominal region changes substantially with time, presumably due to digestive processes. Thus it is important to be aware of the possibility of such artifactual contributions to in vivo fluorescence pharmacokinetic measurements.
PHOTOTHROMBOSIS USING TWO DIFFERENT PHTHALOCYANINE ADMINISTRATION ROUTES: CONTINUOUS I.V. INFUSIO versus BOLUS I.V. INJECTION*
Authors: Tsilimbaris Miltiadis K. , Pallikaris Ioannis G. , Lydataki Stella 
Published: January 2008

Abstract—Chloraluminum sulfonated phthalocyanine was administered in 22 albino rabbits either by means of bolus i.v. (intravenous) injection (6 mg/kg) or as continuous i.v. infusion. Eight animals were used for the comparison of plasma phthalocyanine change as a factor of time, using the two administration methods. Photothrombosis of corneal neovascularization was carried out in the remaining 14 animals either after bolus phthalocyanine injection or after continuous i.v. infusion. Irradiation of the right eye's vessels started 10 min after the injection in the bolus group and 35 min after initiation of infusion in the continuous infusion group. The vessels of each animal's left eye were irradiated 1 h after the irradiation of the right eye. The initial peak of phthalocyanine concentration after bolus injection was followed by a rapid decrease of plasma levels. In the continuous infusion group,30–40 min after the initiation of infusion, plasma phthalocyanine concentration reached a plateau that remained stable for the rest of the80–90 min of infusion. Using bolus injection, a significant decrease of phthalocyanine concentration was accompanied by a significant increase of irradiation time necessary for neovascularization thrombosis in the two eyes. Irradiation time as well as phthalocyanine concentration did not differ between the two eyes using continuous infusion. Vascular photosensitivity seemed to be higher using continuous i.v. infusion of phthalocyanine. Continuous i.v. infusion represents an interesting alternative to bolus injection for phthalocyanine‐mediated corneal neovascularization photothrombosis.
PHOTOSENSITIZED REDUCTION OF L‐BIOPTERIN IN THE ACTIVE TERNARY COMPLEX OF DIHYDROFOLATE REDUCTASE
Authors: Ledbetter John W. , Pfleiderer Wolfgang , Freisheim James H. 
Published: January 2008

Abstract—Photosensitized L‐biopterin induces the transfer of a hydrogen atom from the dihydronico‐tinamide moiety of NADPH to the biopterin ring. Sensitization occurs through the triplet state of both the lactim and lactam tautomers of L‐biopterin. Quenching kinetic analysis to measure the bimolecular rate constant demonstrated a greater reactivity for the lactim tautomer. Recombinant human dihydro‐folate reductase enzyme, for which these molecules are substrate and cofactor, enhanced the rate constant of the photosensitized H• transfer to the apparent lactim tautomer by eight times to 1.6 × 1010M‐1s‐1. When NADP+ replaced NADPH at the active site, no enhanced photoreduction of biopterin was observed, implying that the hydrogen atom comes from the reduced nicotinamide group and not as a result of protein conformational changes. This reduction at the active site represents a photoinitiated H• transfer in protein between substrate and cofactor.
Damage Threshold of Normal Rat Brain in Photodynamic Therapy
Authors: Chen Q. , Chopp M. , Madigan L. , Dereski M. O. , Hetzel F. W. 
Published: January 2008

AbstractNormal brain tissue response to photodynamic therapy (PDT) must be quantified in order to implement PDT as a treatment of brain neoplasm. We therefore calculated the threshold for PDT‐induced tissue necrosis in normal brain using Photofrin (porfimer sodium, Quadralogic Technologies Inc., Vancouver, BC) as the photosensitizer. The absolute light fluence‐rate distribution for superficial irradiation and effective attenuation depth were measured in vivo using an invasive optical probe. Photosensitizer uptake in cerebral cortex was measured with chemical extraction and fluorometric analysis. Photodynamic therapy‐induced lesion depths at various drug dose levels were measured as a biological end point. The PDT threshold for normal brain necrosis was calculated as in the magnitude of 1016 photons/cm3. Thus normal rat brain is extremely vulnerable to PDT damage. This suggests that extra precautions must be exercised when PDT is used in brain.
PUVA Treatment Selectively Induces a Cell Cycle Block and Subsequent Apoptosis in Human T‐Lymphocytes
Authors: Johnson Ray , Staiano‐Coico Lisa , Austin Lisa , Cardinale Irma , Nabeya‐Tsukifuji Reiko , Krueger James G. 
Published: January 2008

ABSTRACTPsoralen plus UVA (320–400 nm radiation; PUVA) is a highly effective therapy for cutaneous diseases caused by skin infiltration with normal or neoplastic T‐lympho‐cytes. In comparing the effects of pharmacologically relevant, low‐dose PUVA treatment on growth of human keratinocytes, peripheral blood leukocytes (PBMC), and T‐lymphocyte cell lines, we determined that PBMC or T‐lymphocytes were >50‐fold more sensitive to cytotoxic effects of PUVA, while antiproliferative effects were produced by similar PUVA levels in all cell types. Low doses of PUVA (10 ng/mL 8‐methoxypsoralen and 1–2 J/cm2) were highly cytotoxic for phytohemagglutinin‐activated normal lymphocytes or transformed T‐lymphocytes as assessed by two viability assays and by flow cytofluo‐rometry. Altered lymphocyte morphology, nuclear fragmentation, TUNEL+ nuclei or nuclear fragments, and the appearance of a sub‐G, DNA peak indicated that cell death occurred by apoptosis, beginning about 1 day after PUVA treatment and continuing for several days thereafter. From assessment of cell cycle progression in mi‐mosine‐synchronized cells, PUVA treatment markedly slowed cell cycle progression, eventually producing cell cycle arrest and apoptotic entry. We propose that the probable basis for disease remissions (psoriasis, cutaneous T‐cell lymphoma) produced by PUVA treatment is through selective cytotoxic effects on clonal T‐lymphocyte populations that are concentrated in diseased skin.
The Effects of ex vivo Handling Procedures on the Near‐Infrared Raman Spectra of Normal Mammalian Tissues
Authors: Shim Martin G. , Wilson Brian C. 
Published: January 2008

ABSTRACTRecent studies in the literature have investigated the feasibility of tissue diagnostics based on Raman spectroscopy. The majority of these compare the ex vivo spectra of normal and diseased tissue. Due to the time lapse between tissue excision and spectroscopic examination, samples must be frozen or otherwise preserved to maintain their native biochemical states. In order to establish optimum procedures for ex vivo Raman spectroscopy of tissue, the effects of tissue drying, formalin fixing, snap freezing, tissue freezing in optimal cutting temperature (OCT) medium and extended post‐thaw durations were studied to determine if any of these handling procedures introduced spectral artifacts. Experiments on representative tissues indicated that tissue heating due to the excitation light did not change the spectra significantly. With minor exceptions, OCT and formalin did not contaminate tissue spectra, so that samples stored for histological examination could also be studied with Raman spectroscopy. Tissue dehydration caused disruption of the protein vibrational modes, which caused spectral artifacts. It is concluded that ex vivo tissue samples should be frozen in OCT. Prior to spectral analysis, the tissue should then be acclimatized at room temperature in phosphate‐buffered saline (PBS) and immersed in PBS during spectroscopic examination.
Subcellular Localization of Sulfonated Tetraphenyl Porphines in Colon Carcinoma Cells by Spectrally Resolved Imaging
Authors: Malik Zvi , Amit Ifat , Rothmann Chana 
Published: January 2008

AbstractSubcellular localization of the dye, 5,10,15,20‐tetra(4‐sul‐fonatophenyl)porphine (TPPS4) and the more hydrophobic dye, 5,10,15,20‐tetra(1‐sulfonatophenyl)porphine (TPPS1), in murine colon carcinoma cells was studied by spectrally resolved imaging (SRI) combined with image processing techniques. Spectrally resolved imaging enabled the acquisition of multipixel fluorescence spectra (>104) from a single cell. Demarcation of specific localization sites and segregation of the irrelevant fluorescence were based on the pixel spectra and by operating the functions of spectral similarity mapping (SSM), principal component analysis (PCA) and spectral classification. The SRI revealed the fine details of the photochemical process that clarify some aspects of subcellular damage. The SRI depicted the differences between TPPS4 and TPPS, with respect to their initial localization and their fate at the end of the photochemical effect. The dye TPPS4 was localized initially in lysosomal vesicles, and upon irradiation fluorescence was seen in the nucleus as well as in vesicles. Some of the vesicles were closely related to the nucleus, as resolved by SSM, PCA and spectral classification. Additional light exposure stimulated relocalization of TPPS4 into the nucleus as well as into the nucleolus, which was clearly depicted by SSM and PCA. Spectral classification showed a third, weak residual cytoplasmic array around the nucleus. The dye TPPS, concentrated in a Golgi‐like complex and was resolved in the nuclear envelope and in small vesicles: it was not redistributed into other compartments upon photosensitization. Serum supplementation to the incubation media of colon carcinoma cells treated with TPPS4 or TPPS, did not change the localization patterns. Pixel spectra of the two dyes in the cells showed spectral shifts and expanded shoulders due to microenvironmental effects. Thus, the chemical nature of the sulfonated phenyl porphines, and not their interaction with serum proteins, was the main determinant of their binding to the lysosomes, nucleus, nucleolus, nuclear envelope or Golgi.
Free Radical Production upon Photoinduced Electron Transfer Reactions in the Presence of Vinyl Monomers. Effect of Water Addition*
Authors: Encinas M. V. , Lissi E. A. , Rufs A. M. , Altamirano M. , Cosa J. J. 
Published: January 2008

AbstractFree radical fragments produced in the photoinduced electron transfer from triethylamine (TEA) to excited pyrenebutyltrimethylammonium (*PyBu+) lead to 1‐vi‐nyl‐2‐pyrrolidinone (VP) and 2‐hydroxyethyl methacry‐late (HEMA) polymerization. Experiments carried out in water/acetonitrile solvent mixtures showed that the polymerization rate of VP increases upon increasing the water content, whereas the polymerization rate of HEMA follows the opposite trend. These results are interpreted in terms of the strong dependence on the solvent properties of the photochemical behavior of PyBu+ in the presence of the amine or monomers. Thus, the *PyBu+ quenching by VP is almost negligible in both solvents (water and acetonitrile). Whereas, the *PyBu+ quenching rate constant by HEMA in water is 4 times 109M−l s−1 and decreases four orders of magnitude in acetonitrile. The quenching of *PyBu+ by TEA in aqueous solutions is controlled by hydrogen‐bonding interactions between water molecules and the amine. Quantum yields of the pyrene radical anion (φPy) also strongly depend on the water content, decreasing from 0.28 to 0.015 upon going from acetonitrile to water.
A Comparative Analysis of Silicon Phthalocyanine Photosensitizers for in vivo Photodynamic Therapy of RIF‐1 Tumors in C3H Mice
Authors: Anderson Cathy Y. , Freye Kristin , Tubesing Karen A. , Li Ying‐Syi , Kenney Malcolm E. , Mukhtar Hasan , Elmets Craig A. 
Published: January 2008

ABSTRACTPhotofrin® photodynamic therapy (PDT) has recently received FDA approval for the palliative treatment of to‐tally and partially obstructing esophageal malignancies. However, there is a need for new PDT photosensitizers because Photofrin has a number of undesirable features. The purpose of this study was to evaluate the efficacy of four amine‐bearing silicon phthalocyanines—Pc4, Pc10, Pc12 and Pc18—as potential PDT photosensitizers. Equimolar concentrations of these Pc were found to be highly effective at causing the regression of RIF‐1 tumors trans‐planted to C3H/HeN mice. The amount of Pc4 necessary to cause an equivalent amount of tumor regression in this model system was substantially less than the amount of Photofrin. The cutaneous phototoxicity of the silicon Pc photosensitizer was assessed by the utilization of the murine ear‐swelling model. When C3H mice were exposed to 167 J/cm2 of polychromatic visible light from a UVB‐filtered solar simulator, which emitted UV radiation and visible light above 320 nm, the Pc produced little, if any, cutaneous photosensitivity. These results indicate that Pc4, Pc10, Pc12 and Pc18 are at least as effective as Photofrin in PDT protocols, while at the same time addressing many of the drawbacks of Photofrin.
Hydrogen‐bonding and Proton Transfer Interactions between Harmane and Trifluoroethanol in the Ground and Excited Singlet States
Authors: Balón Manuel , Carmona Carmen , Guardado Pilar , Muñoz Maria A. 
Published: January 2008

ABSTRACTA study of the hydrogen‐bonding and proton transfer reactions of the ground and excited states of harmane (1‐methyl‐9H‐pyrido/3,4‐b/indole) and its N9‐methyl derivative with 2,2,2‐trifluoroethanol in cyclohexane is reported. Spectral measurements (UV–visible, Fourier trans‐form IR, steady‐state and time‐resolved fluorescence) show the formation of fluorescent ground‐state hydrogen‐bonded complexes. The results have been interpreted assuming a tautomeric equilibrium between a 1:1 hydrogen‐bonded complex and its 1:2 proton transfer tautomer (hydrogen‐bonding ion pair). Upon excitation to its singlet excited state, the proton transfer tautomer of harmane reacts with an additional 2,2,2‐trifluoroethanol molecule to give a zwitterionic exciplex, which fluoresces at longer wavelength.
Anion‐lnduced Fluorescence Quenching of a New Zwitterionic Biacridine Derivative
Authors: Werner Tobias , Fahnrich Karsten , Huber Christian , Wolfbeis Otto S. 
Published: January 2008

AbstractThe effect of halides and different buffer anions on the quenching of the fluorescence of the new probe 10,10′‐bis(3‐sulfopropyl)‐9,9′‐biacridine (SPBA) has been studied using fluorescence and decay time measurements. The linearity of the Stern‐Volmer plot indicates that fluorescence quenching by halides can be described reasonably well by a single‐exponential decay with a K of 4.06 times 106M‐1s‐1for chloride, 7.83 times 106M‐1s‐1for bromide and 1.12 times 107M‐1s‐1for iodide. We have found that SPBA is collisionally quenched also by the buffers 3‐(N‐mor‐pholino)propanesulfonic acid (MOPS) and N‐2‐hydroxy‐ethylpiperazine‐N′‐ethansulfonic acid (HEPES). The bi‐molecular rate constants are 1.67 × 106M‐ls‐1for HEPES and 1.44 times 106M‐1s‐1for MOPS.
Apoptosis Induction in Nonirradiated Human HL‐60 and Murine NSO/2 Tumor Cells by Photoproducts of lndole‐3‐acetic Acid and Riboflavin
Authors: Edwards A. M. , Barredo F. , Silva E. , De Ioannes A. E. , Becker M. I. 
Published: January 2008

AbstractThe effect of the photoproducts of indole‐3‐acetic acid sensitized by riboflavin on nonirradiated human HL‐60 and murine NSO/2 tumor cells was studied. Severe damage with a dose‐response effect was observed on both cell types. The effect was greater than that previously described for the tryptophan riboflavin photoproducts. Electron microscopy studies and flow cytometry analysis of DNA fragmentation allowed us to conclude that the photoproducts studied in this work induce cell death by an apoptotic mechanism.
Optical Sensing of Cesium Using 1,3‐Alternate Calix[4]‐mono‐ and Di(anthrylmethyl)aza‐crown‐6
Authors: Ji Hai‐Feng , Hettich Robert L. , Brown Gilbert M. , Dabestani Reza 
Published: January 2008

AbstractWe have synthesized two derivatives of alkylanthracene covalently bonded to 1,3‐alternate calix[4]aza‐crown‐6 at the nitrogen position to study the effect of alkali metal ion complexation on the emission properties of anthracene fluorophore. The mono‐ and dianthryl‐substituted probes are weakly fluorescent because their emission is partially quenched by photoinduced electron transfer (PET) from the nitrogen lone pair to the excited singlet state of anthracene. Upon complexation of alkali metal ions (e.g. K+, Cs+) by the crown moiety, the nitrogen lone pair can no longer participate in the PET process causing an enhancement in the emission of anthracene fluorophore (fluorescent turn on). The maximum fluorescence enhancement observed upon complexation of cesium ions by mono‐ and dianthryl‐substituted calix[4]aza‐crown‐6 relative to the uncomplexed form was 8.5‐ and 11.6‐fold, respectively.