bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectrally Resolved Imaging of Cabot Rings and Howell‐Jolly Bodies
Authors: Rothmann Chana , Malik Zvi , Cohen Amos M. 
Published: January 2008

AbstractThe spectral characteristics of erythropoietic cellular inclusions stained by May‐Grunwald Giemsa (MGG) were determined by spectrally resolved imaging. Multipixel spectra were obtained from Cabot rings and Howell‐Jolly (HJ) bodies, displaying a range of wavelengths of transmitted light. The spectral characteristics of these inclusions were compared with those of isolated DNA, his‐tones (type II) and arginine‐rich histones (type VI), all stained by MGG. Results of single‐cell spectroscopy show that the spectra of Cabot rings and HJ bodies share spectral characteristics with the type II and type VI histones. However, no resemblance was found between Cabot rings and DNA spectra. The spectral analysis of hetero‐chromatin displayed a spectral pattern with characteristics of both DNA and histones, while the euchromatin showed a major contribution of the DNA component.
The Role of Oxygen in the Antiviral Activity of Hypericin and Hypocrellin
Authors: Park Jaehun , English Doug S. , Wannemuehler Yvonne , Carpenter Susan , Petrich Jacob W. 
Published: January 2008

AbstractThe light‐induced antiviral activity of hypericin and hypocrellin in the presence and absence of oxygen was examined under experimental conditions where the effect of oxygen depletion could be quantified. There was a significant reduction of light‐induced antiviral activity of hypericin and hypocrellin under hypoxic conditions. Interestingly, antiviral activity of hypocrellin was not observed at low oxygen levels at which hypericin retained measurable virucidal activity. This suggests that additional pathways, such as the generation of protons from excited states of hypericin, may enhance the biological activity of activated oxygen species.
Electron Transfer Processes in the Reactivity of Nonsteroidal Anti‐inflammatory Drugs in the Ground and Excited States
Authors: Moore Douglas E , Ghebremeskel Kifle A. , Chen Bruce B. C. , Wong Elaine Y. L. 
Published: January 2008

AbstractThe nonsteroidal anti‐inflammatory drugs (NSAID), naproxen, sulindac and indomethacin, were shown to donate electrons to nitro blue tetrazolium (NBT) when irradiated with UV light in deoxygenated aqueous buffer solution (pH 7.4, 30°C). The reaction was monitored spec‐trophotometrically by the appearance of the diformazan reduction product from NBT. The electron transfer process facilitates the decomposition of the drugs. Naproxen in the presence of NBT is photodegraded principally to the alcohol (2‐[1‐hydroxyethyl]‐6‐methoxynaphthalene) at a rate approximately 20‐fold faster than when irradiated alone in deoxygenated conditions. The photoproduct from naproxen also participates in the electron transfer to NBT but at a much slower rate than naproxen. Irradiation of sulindac or indomethacin in the presence of NBT caused the slow photoreduction of NBT to diformazan. In the absence of NBT, indomethacin and sulindac are essentially unreactive when irradiated in aqueous solution. The ability of a number of NSAID to act as electron donors in their ground state was studied by observing their oxidation by potassium peroxodisulfate in pH 7.0 phosphate buffer at 50°C. The HPLC analysis of the drug remaining showed that the 2‐arylpropionic acid NSAID (naproxen, ibuprofen, ketoprofen and suprofen) reacted at a rate equivalent to the thermal decomposition of peroxodisulfate. The major products were the same as detected in the photooxidation of these drugs, resulting from decarboxylation and oxygen addition but also included a dimeric compound. On the other hand, the NSAID that do not contain the propionic acid substituent all reacted more slowly with peroxodisulfate, enabling specific reaction rate constants to be evaluated.
Photophysical Studies of Some 5,10,15,20‐Tetraarylethynylporphyrinatozinc(II) Complexes as Potential Lead Compounds for Photodynamic Therapy
Authors: Lacey Jackie A. , Phillips David , Milgrom Lionel R. , Yahioglu Gokhan , Rees Robert D. 
Published: January 2008

ABSTRACTThe photophysics of 5,10,15,20‐tetraarylethynylporphyrinatozinc(II) complexes, 1 and 2, are reported. Compared to 5,10,15,20‐tetraphenylporphyrinatozinc(II) (ZnTPP), the UV/visible spectra of 1 and 2 have red‐shifted B and Q bands, with the Q bands of increased intensity relative to the B band. FIuorescence quantum yields and lifetimes and triplet quantum yields and lifetimes are similar to ZnTPP. However, quantum yields for in vitro singlet‐oxygen generation are much larger than for ZnTPP and for 2 the quantum yield is near unity. These findings suggest that the title compounds could be potential lead compounds as sensitizers for photodynamic therapy.
Cytotoxicity and Antiproliferative Effect of Hypericin and Derivatives after Photosensitization
Authors: Vandenbogaerde Ann L. , Delaey Els M. , Vantieghem Annelies M. , Himpens Bernard E. , Merlevede Wilfried J. , de Witte Peter A. 
Published: January 2008

ABSTRACTThe toxicity on three human tumor cell lines (A431, HeLa and MCF7) of five phenanthroperylenequinones (hypericin and derivatives) and two perylenequinones (cercosporin and calphostin C) was investigated after photosensitization (4 J/cm2). Furthermore, the antiproliferative effect on HeLa cells was studied for the phenanthroperylenequinones. Hypericin, 2,5‐dibromohypericin, 2,5,9,12‐tetrabromohypericin and perylenequinones displayed a potent cytotoxic and antiproliferative effect in the nanomolar range. Hypericin dicarboxylic acid exhibited no photoactivity. In general, the antiproliferative activity correlated well with the photocytotoxicity. However, the nonphotocytotoxic compound hexamethylhypericin showed potent antiproliferative activity in the nanomolar range, probably exerting its action by protein kinase C inhibition. Without light irradiation, no cytotoxic and antiproliferative effect was observed for any photocytotoxic phenanthroperylenequinone compound. Furthermore, confocal laser microscopy revealed that the subcellular localization in A431 cells was similar for the photoactive compounds; the photosensitizers were mainly concentrated in the perinuclear region, probably corresponding with the Golgi apparatus and the endoplasmic reticulum. In addition, the accumulation of the photosensitizers in HeLa cells was investigated. All compounds except hypericin dicarboxylic acid were found to concentrate to a large extent in the cells. The compound 2,5,9,12‐tetrabromohypericin seemed intrinsically more effective than hypericin since the intracellular concentration of the bromoderivative was a magnitude of order lower than that of hypericin although both compounds showed similar photobiological activity.
Pharmacokinetics of Tetra (m‐hydroxyphenyl)chlorin in Human Plasma and Individualized Light Dosimetry in Photodynamic Therapy
Authors: Glanzmann Thomas , Hadjur Christophe , Zellweger Matthieu , Grosjean Pierre , Forrer Martin , Ballini Jean‐Pierre , Monnier Philippe , van den Bergh Hubert , Lim Chang Kee , Wagnières Georges 
Published: January 2008

ABSTRACTThe pharmacokinetics of the photosensitizer 5,10,15,20‐tetra(m‐hydroxyphenyl) chlorin(mTHPC) was investigated in the plasma of 20 patients by absorption and fluorescence spectroscopy. The temporal behavior was characterized by a rapid decrease in concentration during the first minutes after intravenous injection of 0.15 mg/kg mTHPC. A minimum concentration in the plasma was reached after about 45 min. The drug concentration then increased again, attaining a maximum after about 10 h, after which it decreased again with a halflife of about 30 h. Irradiation tests in the oral cavity at different time intervals after the injection revealed that the tissue re‐action was only partially correlated with the mTHPC plasma level. The tissue response was stronger at later drug‐light intervals (1–4 days) than during the first hours after injection even though the mTHPC plasma concentration was higher at the shorter times. Relative mTHPC concentrations were also measured in the mucosae of the oral cavity, the esophagus and the bronchi of 27 patients by light‐induced fluorescence spectroscopy using an optical fiber‐based spectrometer. These measurements were performed prior to photodynamic therapy (PDT), 4 days after injection of the photosensitizer. Highly significant linear correlations were found between the relative mTHPC concentrations in the mucosae of these three organs. Likewise, the plasma levels of mTHPC measured just before PDT were significantly correlated with the mTHPC concentrations in the three types of mucosae mentioned above. These results indicate that mTHPC plasma levels measured just before PDT can be used for PDT light dosimetry.
Dark and Photochemical Interactions of Dimethyltetrahydrobenzoangelicin with DNA
Authors: Miolo Giorgia , Lucchini Vittorio , Vedaldi Daniela , Guiotto Adriano , Caffieri Sergio 
Published: January 2008

ABSTRACTA study of dark interaction and photoreaction between 4,6‐dimethyltetrahydrobenzoangelicin (THBA) and DNA is described. 4,6‐Dimethyltetrahydrobenzoangelicin is a furocoumarin derivative in which 4’and 5’carbons are linked by a four‐methylene bridge. In spite of the bulky aliphatic ring, THBA forms a complex with DNA in the dark and, on UVA irradiation, reacts with pyrimidine bases of DNA yielding monoadducts only involving its furan side double bond. Two main photoproducts form: they derive from a C4‐cycloaddition to thymine and cytosine, respectively, and account for 56% and 39% of the total photoreaction yield. Both show cis‐syn configuration. Two other isomers, one with thymine and one with cytosine, formed with so much lower yield (ca 3 and 1%, respectively) that their structure could not be assigned. Furthermore, in spite of its angular structure, THBA induces a small number of crosslinks in DNA.
Changes of Chlorophyll(ide) Fluorescence Yield Induced by a Short Light Pulse as a Probe to Monitor the Early Steps of Etioplast Phototransformation in Dark‐Grown Leaves
Authors: Eullaffroy Philippe , Popovic Radovan , Franck Fabrice 
Published: January 2008

ABSTRACTThe fluorescence yield of chlorophyll(ide) (Chl[ide]) excited by weak modulated light was recorded at room temperature during a 2 h period after a short actinic light pulse that transformed all photoactive protochlorophyllide in dark‐grown barley leaves. A typical pattern of fluorescence yield variations was found whatever the age of the leaf but with age‐dependent changes in rates. Its successive phases were related to the Chl(ide) spectral shifts observed in low‐temperature emission spectra. The fluorescence yield started at a high level and strongly declined during the formation of Chlide695from Chlide668within a few seconds. It increased to a transient maximum during the Shibata shift (15–25 min) that resulted in Chl(ide)682. A final, slow decrease to a steady state occurred during the final red shift to Chl685. Pretreatments with δ‐aminolevulinic acid, chloramphenicol or 1, 10‐phenanthroline resulted in correlated modifications of Chl(ide) fluorescence yield transients and shifts of the low‐temperature Chl(ide) emission band. The complex response of the final decrease phase of the fluorescence yield to these compounds suggests that it results both from the assembly of photosynthetic Chl proteins and from the reorganization of the etioplast membrane system. From these results it is concluded that continuous recordings of Chl(ide) fluorescence yield after a short light pulse represent a useful tool to monitor the kinetics of pigment–protein organization and primary thylakoid assembly triggered by Pchlide photoreduction.
Laser Photolysis of Chromium(lll) Porphyrins in Toluene Solutions. Effects of Oxygen on the Photodissociation Yields of the Axial Ligands
Authors: Inamo Masahiko , Hoshino Mikio 
Published: January 2008

AbstractThe effects of oxygen on the photochemical reactions of chromium(III) porphyrins with axial nitrogenous bases in toluene are studied by nanosecond laser flash photolysis. The photodissociation of the axial bases is confirmed to occur via both the excited states 4S1 and 6T1 (and/or 4T1) on the basis of the effect of oxygen on the quantum yield of photoreaction.
13‐Acetoxy‐13‐desmethylretinal‐14‐3H: Synthesis and Interaction with Bacterioopsin
Authors: Seltzer Stanley 
Published: January 2008

AbstractThe title compound (4) was synthesized in three steps from 1,1‐dimethoxy‐7‐methyl‐9‐(2′,6′,6′‐trimethyl‐1‐cy‐clohexen‐1‐yl)‐4E,6E,8E‐nonatrien‐3‐one (1). Interaction of 4 with bacterioopsin produced a pigment absorbing at 573 nm, which, on long standing in the dark, moves to 406 nm, mirroring the behavior of nonradioactive 4 with bacterioopsin (S. Seltzer, J. Org. Chem. 60, 1189–1194, 1993). Compound 4 was designed to test for the involvement of a nucleophilic side chain, presumably asp‐212, in catalyzing the dark cis‐trans isomerization of bound retinal, through its attack at C‐13. Such a mechanism is anticipated to lead to a cross‐linked product where the nucleophile replaces the 13‐acetoxy group when 4 is substituted for the natural chromophore. The protein, reconstituted with 4, after extensive washing, solubilization in dimethylsulfoxide and extensive dialysis retains its radioactivity suggesting the establishment of a cross‐link. Solution in 6 M urea, however, results in substantial loss of radioactivity, suggesting that the unfolded labeled protein suffers hydrolysis of the very labile 13‐enolester group followed by proton exchange.
Fluorescence Studies of Lens Epithelial Cells and Their Constituents
Authors: Atherton Stephen J. , Lambert Chris , Schultz Joanne , Williams Natalie , Zigman Seymour 
Published: January 2008

AbstractSteady‐state and time‐resolved fluorescence measurements have been made of human and rabbit lens epithelial cells and their total soluble protein. Excitation at 350 nm results in broad fluorescence spectra peaking at 450 nm and stretching into the visible past 650 nm. The fluorescence excitation spectra peak around 350 nm. We assign the species responsible for this absorption and fluorescence as NADPH. Because the absorption of near‐UV light (300–400 nm) is responsible for cell damage and death, we postulate that excited states of NADPH are implicated in the mechanisms of cell damage. Preirradia‐tion with 355 nm light leads to a loss of NADPH fluorescence but with no change in decay kinetics. Possible mechanisms for cell damage are explored.
(2+4)‐Cycloaddition with Singlet Oxygen.17O‐lnvestigation of the Reactivity of Furfuryl Alcohol Endoperoxide¶
Authors: Braun André M. , Dahn Hans , Gassmann Ernst , Gerothanassis Ioannis , Jakob Laurent , Kateva Jordanka , Martinez Claudia G. , Oliveros Esther 
Published: January 2008

AbstractIn earlier work, the use of furfuryl alcohol as a specific singlet oxygen acceptor was proposed because of the high ratio between the rate constants of chemical reaction and physical quenching. In contrast to furfuryl aldehyde, a number of products are formed by this type II photo‐oxidation of furfuryl alcohol. These products may be derived from the endoperoxide of furfuryl alcohol as a common intermediate. The present work focuses on the reactivity of this endoperoxide that was marked specifically by the use of17O2as a source for singlet oxygen. The analyses of the stable products, their yields and their labeling distribution reveal a strong solvent effect on the primary reaction pathways, and nucleophilic substitution reactions leading to hydroperoxide intermediates are dominant.
Preparation, Phototoxicity and Biodistribution Studies of Anti‐Carcinoembryonic Antigen Monoclonal Antibody‐Phthalocyanine Conjugates
Authors: Carcenac Magali , Larroque Christian , Langlois Rejean , van Lier Johan E. , Artus Jean‐Claude , Pelegrin Andre 
Published: January 2008

AbstractImmunophototherapy of cancer combines the specificity of a monoclonal antibody (MAb) to an overexpressed tumor marker with the phototoxic properties of a conjugated dye. Aluminum tetrasulfophthalocyanine (AlPcS4) was covalently coupled to a 35A7 MAb directed against carcinoembryonic antigen (CEA) via a five‐carbon spacer chain (A1) to yield conjugates with a molar ratio ranging from 5 to 16 mol of AlPcS4 per mol of 35A7 MAb. Conjugates were labeled with radioiodine for characterization. The immunoreactivity of the conjugates, determined in a direct binding assay on CEA coupled to sepharose, was not modified by the coupled AlPcS4A1 molecules. In vivo, these conjugates were evaluated in nude mice bearing human colon carcinoma xenografts (T380). 35A7 MAb‐(AlPcS4A1)s, 35A7 MAb‐(AlPcS4A1,)12 and 35A7 MAb‐(AIPcS4A,)16 conjugates displayed a tumor uptake of 35 ± 5.0%, 40 ± 5.7% and 32 ± 3.3% of the injected dose per gram of tumor tissue, respectively, corresponding to an uptake of 97%, 104% and 91% as compared to that of the unconjugated 35A7 MAb. In each experimental group, the tumor‐to‐normal tissue ratios obtained with the conjugates were almost identical to those obtained with unconjugated 35A7 MAb. Average values of 1.8, 7 and about 30 were obtained for blood, liver and muscle, respectively. Phototoxic efficacy of the 35A7 MAb‐(AlPcS4A,)12 conjugate was demonstrated in vitro on the LoYo cell line giving a 91 % growth inhibition for a 2.50 μ/mL AlPcS4A1 concentration. We conclude that these conjugates demonstrate clear in vivo tumor‐seeking capacity and in vitro photocytotoxic properties. Such conjugates could thus be promising candidate drugs for clinical photodynamic therapy of cancers expressing CEA.
The ALCAM Shedding by the Metalloprotease ADAM17/TACE Is Involved in Motility of Ovarian Carcinoma Cells
Authors: Rosso Ombretta , Piazza Tiziana , Bongarzone Italia , Rossello Armando , Mezzanzanica Delia , Canevari Silvana , Orengo Anna Maria , Puppo Andrea , Ferrini Silvano , Fabbi Marina 
Published: January 2008

Abstract
Previous findings indicated that the activated leukocyte cell adhesion molecule (ALCAM) is expressed by tumors and plays a role in tumor biology. In this study, we show that ALCAM is shed from epithelial ovarian cancer (EOC) cells in vitro, leading to the generation of a soluble ALCAM (sALCAM), consisting of most of the extracellular domain. A similar sALCAM molecule was also found in the ascitic fluids and sera from EOC patients, suggesting that this process also occurs in vivo. sALCAM is constitutively produced by EOC cells, and this process can be enhanced by cell treatment with pervanadate, phorbol 12-myristate 13-acetate (PMA), or epidermal growth factor (EGF), a known growth factor for EOC. Pharmacologic inhibitors of matrix metalloproteinases (MMP) and of a disintegrin and metalloproteases (ADAM), and the tissue inhibitor of metalloproteinase-3, significantly inhibited sALCAM release by EOC cells. The ADAM17/TACE molecule was expressed in EOC cell lines and ADAM17/TACE silencing by specific small interfering RNA–reduced ALCAM shedding. In addition, inhibitors of ADAM function blocked EOC cell motility in a wound-healing assay. Conversely, a recombinant antibody blocking ALCAM adhesive functions and inducing ALCAM internalization enhanced EOC cell motility. Altogether, our data suggest that the disruption of ALCAM-mediated adhesion is a relevant step in EOC motility, and ADAM17/TACE takes part in this process, which may be relevant to EOC invasive potential. (Mol Cancer Res 2007;5(12):1246–53)
Inhibition of Intestinal Polyposis with Reduced Angiogenesis in ApcMin/+ Mice Due to Decreases in c-Myc Expression
Authors: Yekkala Krishna , Baudino Troy A. 
Published: January 2008

Abstract
The c-myc oncogene plays an important role in tumorigenesis and is frequently deregulated in many human cancers, including gastrointestinal cancers. In humans, mutations of the adenomatous polyposis coli (Apc) tumor suppressor gene occur in most colorectal cancers. Mutation of Apc leads to stabilization of β-catenin and increases in β-catenin target gene expression (c-myc and cyclin D1), whose precise functional significance has not been examined using genetic approaches. ApcMin/+ mice are a model of familial adenomatous polyposis and are heterozygous for an Apc truncation mutation. We have developed a model for examining the role of c-Myc in Apc-mediated tumorigenesis. We crossed c-myc+/− mice to ApcMin/+ to generate ApcMin/+ c-myc+/− animals. The compound ApcMin/+ c-myc+/− mice were used to evaluate the effect of c-myc haploinsufficiency on the ApcMin/+ phenotype. We observed a significant reduction in tumor numbers in the small intestine of ApcMin/+ c-myc+/− mice compared with control ApcMin/+ c-myc+/+ mice. In addition, we observed one to three polyps per colon in ApcMin/+ c-myc+/+ mice, whereas only two lesions were observed in the colons of ApcMin/+ mice that were haploinsufficient for c-myc. Moreover, reduction in c-myc levels resulted in a significant increase in the survival of these animals. Finally, we observed marked decreases in vascular endothelial growth factor, EphA2, and ephrin-B2 expression as well as marked decreases in angiogenesis in intestinal polyps in ApcMin/+ c-myc+/− mice. This study shows that c-Myc is critical for Apc-dependent intestinal tumorigenesis in mice and provides a potential therapeutic target in the treatment of colorectal cancer. (Mol Cancer Res 2007;5(12):1296–303)
Defective in Mitotic Arrest 1/Ring Finger 8 Is a Checkpoint Protein That Antagonizes the Human Mitotic Exit Network
Authors: Tuttle Robyn L. , Bothos John , Summers Matthew K. , Luca Francis C. , Halazonetis Thanos D. 
Published: January 2008

Abstract
A molecular pathway homologous to the S. cerevisiae mitotic exit network (MEN) and S. pombe septation initiation network has recently been described in higher eukaryotes and involves the tumor suppressor kinase LATS1 and its subunit MOB1A. The yeast MEN/septation initiation network pathways are regulated by the ubiquitin ligase defective in mitotic arrest 1 (Dma1p), a checkpoint protein that helps maintain prometaphase arrest when cells are exposed to microtubule poisons. We identified here the RING domain protein ring finger 8 (RNF8) as the human orthologue of the yeast protein Dma1p. Like its yeast counterparts, human DMA1/RNF8 localized at the midbody and its depletion by siRNA compromised mitotic arrest of nocodazole-treated cells in a manner dependent on the MEN. Depletion of MAD2, a spindle checkpoint protein, also compromised mitotic arrest, but in a MEN-independent manner. Thus, two distinct checkpoint pathways maintain mitotic arrest in cells exposed to microtubule poisons. (Mol Cancer Res 2007;5(12):1304–11)