@article {2422, title = {Thymic progenitor homing and lymphocyte homeostasis are linked via S1P-controlled expression of thymic P-selectin/CCL25}, journal = {Journal of Experimental Medicine}, volume = {206}, number = {4}, year = {2009}, note = {ISI Document Delivery No.: 444VXTimes Cited: 19Cited Reference Count: 55Gossens, Klaus Naus, Silvia Corbel, Stephane Y. Lin, Shujun Rossi, Fabio M. V. Kast, Joergen Ziltener, Hermann J.}, month = {Apr}, pages = {761-778}, type = {Article}, abstract = {Thymic T cell progenitor (TCP) importation is a periodic, gated event that is dependent on the expression of functional P-selectin ligands on TCPs. Occupancy of intrathymic TCP niches is believed to negatively regulate TCP importation, but the nature of this feedback mechanism is not yet resolved. We show that P-selectin and CCL25 are periodically expressed in the thymus and are essential parts of the thymic gate-keeping mechanism. Periodicity of thymic TCP receptivity and the size of the earliest intrathymic TCP pool were dependent on the presence of functional P-selectin ligand on TCPs. Furthermore, we show that the numbers of peripheral blood lymphocytes directly affected thymic P-selectin expression and TCP receptivity. We identified sphingosine-1-phosphate (S1P) as one feedback signal that could mediate influence of the peripheral lymphocyte pool on thymic TCP receptivity. Our findings suggest a model whereby thymic TCP importation is controlled by both early thymic niche occupancy and the peripheral lymphocyte pool via S1P.}, keywords = {ADULT-MOUSE, ENDOTHELIAL-CELLS, EPITHELIAL-CELLS, KAPPA-B, LIGAND PSGL-1, MICE, NECROSIS-FACTOR-ALPHA, P-SELECTIN, PLASMA SPHINGOSINE 1-PHOSPHATE, T-CELLS}, isbn = {0022-1007}, url = {://000266009600006}, author = {Gossens, K. and Naus, S. and Corbel, S. Y. and Lin, S. J. and Rossi, F. M. V. and Kast, J. and Ziltener, H. J.} } @article {1307, title = {Synthesis of pelorol and analogues: Activators of the inositol 5-phosphatase SHIP}, journal = {Organic Letters}, volume = {7}, number = {6}, year = {2005}, note = {ISI Document Delivery No.: 906DPTimes Cited: 19Cited Reference Count: 18}, month = {Mar}, pages = {1073-1076}, type = {Article}, abstract = {A screening program designed to find new antiinflammatory agents has identified the sponge meroterpenoid pelorol (1) as an in vitro activator of the inositol-5-phosphatase SHIP. Pelorol (1) and several functional group analogues have been synthesized from sclareolide (4).}, keywords = {CELLS, METABOLITE, MICE, SPONGE DACTYLOSPONGIA-ELEGANS}, isbn = {1523-7060}, url = {://000227621000030}, author = {Yang, L. and Williams, D. E. and Mui, A. and Ong, C. and Krystal, G. and Van Soest, R. and Andersen, R. J.} } @article {1091, title = {The toxicity of trimethylarsine: an urban myth}, journal = {Journal of Environmental Monitoring}, volume = {7}, number = {1}, year = {2005}, note = {ISI Document Delivery No.: 896IBTimes Cited: 7Cited Reference Count: 50}, month = {Jan}, pages = {11-15}, type = {News Item}, keywords = {DISEASE, IN-VITRO, METHYLATION, MICE, STACHYBOTRYS-CHARTARUM}, isbn = {1464-0325}, url = {://000226926700007}, author = {Cullen, W. R. and Bentley, R.} } @article {330, title = {Plasmid DNA damage caused by methylated arsenicals, ascorbic acid and human liver ferritin}, journal = {Toxicology Letters}, volume = {133}, number = {1}, year = {2002}, note = {ISI Document Delivery No.: 575QMTimes Cited: 46Cited Reference Count: 499th International Congress of ToxicologyJUL 08-12, 2001BRISBANE, AUSTRALIA}, month = {Jul}, pages = {47-57}, type = {Proceedings Paper}, abstract = {Both dimethylarsinic acid (DMA(V)) and dimethylarsinous acid (DMA(III)) release iron from human liver ferritin (HLF) with or without the presence of ascorbic acid. With ascorbic acid the rate of iron release from HLF by DMA(V) was intermediate (3.37 nM/min, P < 0.05) and by DMA(III) was much higher (16.3 nM/min, P < 0.001). No pBR322 plasmid DNA damage was observed from in vitro exposure to arsenate (iAs(V)), arsenite (iAs(III)), monomethylarsonic acid (MMA(V)), monomethylarsonous acid (MMA(III)) or DMA(V) alone. DNA damage was observed following DMA(III) exposure; coexposure to DMA(III) and HLF caused more DNA damage; considerably higher amounts of DNA damage was caused by coexposure of DMA(III), HLF and ascorbic acid. Diethylenetriaminepentaacetic acid (an iron chelator), significantly inhibited DNA damage. Addition of catalase (which can increase Fe2+ concentrations) further increased the plasmid DNA damage. Iron-dependent DNA damage could be a mechanism of action of human arsenic carcinogenesis. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.}, keywords = {arsenic, BIOCHEMICAL PARAMETERS, CARCINOGENESIS, DIMETHYLARSINIC ACID, dimethylarsinous acid, DMA(111), DNA damage, ENDOTHELIAL-CELLS, human liver ferritin, INDUCTION, INORGANIC ARSENICS, iron, MICE, MONOMETHYLARSONOUS ACID, reactive oxygen, species, STRAND BREAKS}, isbn = {0378-4274}, url = {://000176959200005}, author = {Ahmad, S. and Kitchin, K. T. and Cullen, W. R.} } @article {4901, title = {Monomethylarsonous acid (MMA(III)) is more toxic than arsenite in Chang human hepatocytes}, journal = {Toxicology and Applied Pharmacology}, volume = {163}, number = {2}, year = {2000}, note = {ISI Document Delivery No.: 295TBTimes Cited: 294Cited Reference Count: 28}, month = {Mar}, pages = {203-207}, type = {Article}, abstract = {Methylation has been considered to be the primary detoxication pathway of inorganic arsenic. Inorganic arsenic is methylated by many, but not all animal species, to monomethylarsonic acid (MMA(V)), monomethylarsonous acid (MMA(III)), and dimethylarsinic acid (DMA(V)). The As-V derivatives have been assumed to produce low toxicity, but the relative toxicity of MMA(III) remains unknown. In vitro toxicities of arsenate, arsenite, MMA(V), MMA(III) and DMA(V) were determined in Chang human hepatocytes, Leakage of lactate dehydrogenase (LDH) and intracellular potassium (K+) and mitochondrial metabolism of the tetrazolium salt XTT were used to assess cytotoxicity due to arsenic exposure. The mean LC50 based on LDH assays in phosphate media was 6 mu M for MMA(III) and 68 mu M for arsenite. Using the assay for K+ leakage in phosphate media, the mean LC50 was 6.3 mu M for MMA(III) and 19.8 mu M for arsenite. The mean LC50 based on the XTT assay in phosphate media was 13.6 mu M for MMA(III) and 164 mu M for arsenite. The results of the three cytotoxicity assays (LDH, K+, and XTT) reveal the following order of toxicity in Chang human hepatocytes: MMA(III) > arsenite > arsenate > MMA(V) = DMA(V). Data demonstrate that MMA(III) an intermediate in inorganic arsenic methylation, is highly toxic and again raises the question as to whether methylation of inorganic arsenic is a detoxication process. (C) 2000 Academic Press.}, keywords = {ARSENATE, ARSENITE, ASSAY, CELLS, Chang human hepatocytes, DIMETHYLARSINIC ACID, DMA, DMA(V), DMPS, ENZYMATIC METHYLATION, LDH, LIVER, MICE, MMA(III), MMA(V), monomethylarsonic acid, MONOMETHYLARSONOUS ACID, POTASSIUM, VIABILITY, XTT}, isbn = {0041-008X}, url = {://000085983000013}, author = {Petrick, J. S. and Ayala-Fierro, F. and Cullen, W. R. and Carter, D. E. and Aposhian, H. V.} } @article {4139, title = {Comparative inhibition of yeast glutathione reductase by arsenicals and arsenothiols}, journal = {Chemical Research in Toxicology}, volume = {10}, number = {1}, year = {1997}, note = {ISI Document Delivery No.: WD805Times Cited: 165Cited Reference Count: 30}, month = {Jan}, pages = {27-33}, type = {Article}, abstract = {Tri(gamma-glutamylcysteinylglycinyl)trithioarsenite (As-III(GS)(3)) is formed in cells and is a more potent mixed-type inhibitor of the reduction of glutathione disulfide (GSSG) by yeast glutathione (GSH) reductase than either arsenite (As-III) or GSH. The present work examines the effects of valence and complexation of arsenicals with GSH or L-cysteine (Cys) upon potency as competitive inhibitors of the reduction of GSH disulfide (GSSG) by yeast GSH reductase. Trivalent arsenicals were more potent inhibitors than their pentavalent analogs, and methylated trivalent arsenicals were more potent inhibitors than was inorganic trivalent As. Complexation of either inorganic trivalent As or methylarsonous diiodide ((CH3AsI2)-I-III) with Cys or GSH produced inhibitors of GSH reductase that were severalfold more potent than the parent arsenicals. In contrast, dimethylarsinous iodide ((CH3)(2)(AsI)-I-III) was a more potent inhibitor than its complexes with either GSH or Cys. Complexes of CH3AsIII with GSH (CH3AsIII(GS)(2)) or with Cys (CH3AsIII(Cys)(2)) were the most potent inhibitors, with K-i{\textquoteright}s of 0.009 and 0.018 mM, respectively. Inhibition of GSH reductase by arsenicals or arsenothiols was prevented by addition of meso-2,3-dimercaptosuccinic acid (DMSA) to a mixture of enzyme, GSSG, and inhibitor before addition of NADPH. DMSA added to the reaction mixture after NADPH reversed inhibition by (CH3)(2)(AsI)-I-III but had little effect on inhibition by (CH3AsI2)-I-III, CH3AsIII(GS)(2), CH3AsIII(Cys)(2), Or AS(III)(GS)(3). Partial redox inactivation of the enzyme with NADPH increased the inhibitory potency of (CH3AsI2)-I-III and (CH3)(2)(AsI)-I-III and changed the mode of inhibition for (CH3AsI2)-I-III from competitive to noncompetitive. The greater potency of methylated trivalent arsenicals and arsenothiols than of inorganic trivalent As suggests that biomethylation of As could yield species that inhibit reduction of GSSG and alter the redox status of cells.}, keywords = {BINDING, DIMERCAPTOSUCCINIC ACID, Disulfide, MAGNETIC-RESONANCE, MICE, PHENYLDICHLOROARSINE, RABBIT ERYTHROCYTES}, isbn = {0893-228X}, url = {://A1997WD80500004}, author = {Styblo, M. and Serves, S. V. and Cullen, W. R. and Thomas, D. J.} } @article {4160, title = {Magnetic resonance imaging evaluation of photodynamic therapy-induced hemorrhagic necrosis in the murine M1 tumor model}, journal = {Photochemistry and Photobiology}, volume = {66}, number = {6}, year = {1997}, note = {ISI Document Delivery No.: YN097Times Cited: 11Cited Reference Count: 19}, month = {Dec}, pages = {847-852}, type = {Article}, abstract = {Proton magnetic resonance imaging (MRI) and histological methods were used to evaluate photodynamic therapy (PDT)-induced hemorrhagic necrosis in the murine M1 tumor within 72 h of treatment of male DBA/2 mice, The effects of three photosensitizing drugs were investigated: Photofrin(R) (n = 4), Zn (II) phthalocyanine (n = 7) and benzoporphyrin derivative monoacid ring A (n = 11). As noted in previous studies of PDT using MRI, MRI makes possible serial, noninvasive, in vivo observation of tissue response to PDT. Our serial study of MRI and histological data confirms that tumors responded in the same way to PDT treatment using the three photosensitizing drugs: vascular damage followed by hemorrhagic necrosis. Most importantly and unlike previous MRI studies of PDT, we used a very high field magnet that enhanced the effect of magnetic susceptibility on image signal when blood is processed by the body after PDT-induced hemorrhagic necrosis. This last finding demonstrates the utility of high field magnets and the importance of localized, serial experiments in future magnetic resonance studies of PDT.}, keywords = {MICE, NORMAL BRAIN, SPECTROSCOPY}, isbn = {0031-8655}, url = {://000071132800021}, author = {Winsborrow, B. G. and Grondey, H. and Savoie, H. and Fyfe, C. A. and Dolphin, D.} } @article {3017, title = {1993 SYNTEX-AWARD LECTURE - PHOTOMEDICINE AND PHOTODYNAMIC THERAPY}, journal = {Canadian Journal of Chemistry-Revue Canadienne De Chimie}, volume = {72}, number = {4}, year = {1994}, note = {ISI Document Delivery No.: NN830Times Cited: 84Cited Reference Count: 47}, month = {Apr}, pages = {1005-1013}, type = {Article}, abstract = {Photodynamic therapy (PDT) involves the treatment of diseased tissue and cells using a photosensitizer and visible light. Such photomedical treatments have been known since the time of the ancient Egyptians but it was only just this year that this therapeutic modality was made available to modern medicine with the approval, in Canada, of Photofrin(R) for the treatment of bladder cancer. This paper reviews PDT with an emphasis on drug development, particulary for the second generation drugs, especially BPDMA (benzoporphyrin derivative-mono acid), which is now in human clinical trials.}, keywords = {BENZOPORPHYRIN DERIVATIVES, CELLS, HEMATOPORPHYRIN, INACTIVATION, MICE, PHOTOSENSITIZATION, PLASMA-LIPOPROTEINS, porphyrins, PROTEIN DAMAGE, PROTOPORPHYRIN}, isbn = {0008-4042}, url = {://A1994NN83000001}, author = {Dolphin, D.} } @article {3114, title = {IN-VIVO INHIBITION OF BETA-GLUCOSIDASE AND BETA-MANNOSIDASE ACTIVITY IN RATS BY 2-DEOXY-2-FLUORO-BETA-GLYCOSYL FLUORIDES AND RECOVERY OF ACTIVITY IN-VIVO AND IN-VITRO}, journal = {Biochemical Journal}, volume = {301}, year = {1994}, note = {ISI Document Delivery No.: PA559Times Cited: 12Cited Reference Count: 25Part 2}, month = {Jul}, pages = {343-348}, type = {Article}, abstract = {2-Deoxy-2-fluoro-beta-glucosyl and -beta-mannosyl fluorides administered to rats in a single dose(10 mg/kg) inhibited beta-glucosidase and beta-mannosidase activity respectively after 1 h in brain, spleen, liver and kidney tissues. This inhibition, presumably caused by accumulation of 2-deoxy-2-fluoroglycosyl-enzyme intermediates, indicates that intact 2-deoxy-2-fluoroglycosyl fluorides are distributed to these organs and, in the case of brain, that they cross the blood/brain barrier. beta-Glucosidase activity recovered completely or partially in brain, spleen, liver and kidney by 20-48 h. beta-Mannosidase activity partially recovered in all tissues by 48 h. beta-Galactosidase activity in brain and kidney was not significantly affected by administration of either the gluco or manno compounds at this dosage, indicating that these inhibitors are directed towards specific glycosidases. Observation of similar relatively rapid rates of beta-glycosidase re-activation in vivo and in tissue homogenates in vitro at 37 degrees C suggests that hydrolysis or transglycosylation of 2-deoxy-2-fluoroglycosyl-enzymes, not protein synthesis, are the primary mechanisms involved in the recovery of glycosidase activity inhibited by this class of compounds in vivo.}, keywords = {DEFICIENCY, ENZYME INTERMEDIATE, FORMS, GLUCOCEREBROSIDASE, GLYCOSIDASES, INACTIVATION, LIVER, MICE}, isbn = {0264-6021}, url = {://A1994PA55900006}, author = {McCarter, J. D. and Adam,Michael J. and Hartman, N. G. and Withers, S. G.} }