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Rieger AL, Edwards JO, Levey G. PHOTOOXIDATION OF MAGNESIUM TETRAPHENYLPORPHYRIN IN THE PRESENCE OF METHYL VIOLOGEN. Photochem Photobiol 1983. [DOI: 10.1111/j.1751-1097.1983.tb03852.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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252
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Klimek J, Schaap AP, Kimura T. Effect of paraquat on cytochrome P-450-dependent lipid peroxidation in bovine adrenal cortex mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA 1983; 752:127-36. [PMID: 6849960 DOI: 10.1016/0005-2760(83)90240-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We have investigated the effect of paraquat (methyl viologen) on lipid peroxidation in bovine adrenal cortex mitochondria. Incubation of a buffered aerobic mixture of mitochondria in the presence of Fe2+ or NADPH resulted in the formation of lipid peroxides whose accumulation could be followed at 532 nm as malondialdehyde. Fe2+ stimulates lipid peroxidation in normal mitochondria and those in which enzymes have been inactivated with heat. In contrast, NADPH has a stimulatory effect only in normal mitochondria, but not in heat-treated mitochondria. These results indicate that NADPH-dependent lipid peroxidation is an enzymatic process. Paraquat strongly inhibits this enzymatic lipid peroxidation, but has no effect on the non-enzymatic Fe2+-dependent process. The chemiluminescence that accompanies the NADPH-dependent lipid peroxidation is also markedly decreased in the presence of paraquat. Superoxide dismutase, which removes superoxide anion efficiently, does not inhibit malondialdehyde production. The mechanism of the inhibition of the lipid peroxidation by paraquat has been examined. Paraquat has no effect on NADPH-2,6-dichlorophenolindophenol reductase and on NADPH-cytochrome c reductase activities in bovine adrenal cortex mitochondria. However, paraquat strongly inhibits the NADPH-dependent reduction of cytochrome P-450. These results suggest that the inhibitory effect of paraquat on NADPH-dependent lipid peroxidation in adrenal cortex mitochondria is due to a decrease in the level of reduced cytochrome P-450 probably by diverting electrons from cytochrome P-450. Cytochrome c, which can compete with P-450 for available electrons from adrenodoxin, like paraquat had an inhibitory effect on NADPH-dependent lipid peroxidation. Lipid peroxidation was also strongly inhibited by steroid hydroxylase inhibitors, e.g., amphenone B, aminoglutethimide and metyrapone.
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254
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Rabinowitch HD, Fridovich I. SUPEROXIDE RADICALS, SUPEROXIDE DISMUTASES and OXYGEN TOXICITY IN PLANTS. Photochem Photobiol 1983. [DOI: 10.1111/j.1751-1097.1983.tb04540.x] [Citation(s) in RCA: 148] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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255
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Maurette MT, Oliveros E, Infelta PP, Ramsteiner K, Braun AM. Singlet Oxygen and Superoxide: Experimental Differentiation and Analysis. Helv Chim Acta 1983. [DOI: 10.1002/hlca.19830660236] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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256
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Cox GS, Whitten DG. Excited state interactions of protoporphyrin IX and related porphyrins with molecular oxygen in solutions and in organized assemblies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1983; 160:279-92. [PMID: 6837355 DOI: 10.1007/978-1-4684-4406-3_24] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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258
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Sata T, Takeshige K, Takayanagi R, Minakami S. Lipid peroxidation by bovine heart submitochondrial particles stimulated by 1,1'-dimethyl-4,4'-bipyridylium dichloride (paraquat). Biochem Pharmacol 1983; 32:13-9. [PMID: 6830607 DOI: 10.1016/0006-2952(83)90645-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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260
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Hydrogen production using chloroplast membranes without oxygen scavengers: An assay with hydrogenases from aerobic hydrogen-oxidizing bacteria and flavodoxins from Desulfovibrio sp. ACTA ACUST UNITED AC 1983. [DOI: 10.1007/bf00505881] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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261
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Keeling PL, Smith LL. Relevance of NADPH depletion and mixed disulphide formation in rat lung to the mechanism of cell damage following paraquat administration. Biochem Pharmacol 1982; 31:3243-9. [PMID: 7150352 DOI: 10.1016/0006-2952(82)90557-3] [Citation(s) in RCA: 81] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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262
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Catalysis of the reduction of dioxygen by poly(xylylviologen) coatings on graphite electrodes. ACTA ACUST UNITED AC 1982. [DOI: 10.1016/0022-0728(82)85135-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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263
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Ohno T, Kato S, Lichtin NN. Electron Transfer in the Quenching of Triplet States of Zinc Phthalocyanine and Methylene Blue by the Use of Fe(III), Co(III), and Organic Oxidants. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1982. [DOI: 10.1246/bcsj.55.2753] [Citation(s) in RCA: 35] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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264
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Ebbesen TW, Levey G, Patterson LK. Photoreduction of methyl viologen in aqueous neutral solution without additives. Nature 1982. [DOI: 10.1038/298545a0] [Citation(s) in RCA: 67] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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265
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Siefkin AD. Combined paraquat and acetaminophen toxicity. JOURNAL OF TOXICOLOGY. CLINICAL TOXICOLOGY 1982; 19:483-91. [PMID: 7175993 DOI: 10.3109/15563658208992503] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A case of combined paraquat and acetaminophen ingestion is reported with accompanying serial serum levels (including pre- and postcharcoal hemoperfusion) and autopsy tissue levels of both toxins. An increased lethality (time until death) is suggested in rats receiving both toxins as compared to either toxin alone. A proposed mechanism for the combined toxicity of the two drugs is hypothesized.
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Abstract
Paraquat (1,1'-dimethyl-4,4'-bipyridinium dichloride) was used as an intracellular generator of oxygen free radicals and was found to be highly mutagenic for Salmonella typhimurium. It caused both base-pair substitution and frameshift mutations. Paraquat was much more toxic and mutagenic in a simple nutritionally restricted medium than in a rich complex medium. The mutagenicity of paraquat was dependent upon the presence of a supply of both electrons and oxygen. Cells containing high levels of superoxide dismutase (superoxide:superoxide oxidoreductase, EC 1.15.1.1) were more resistant to the toxicity and the mutagenicity of paraquat than were cells containing normal levels of this enzyme. The mutagenicity of paraquat thus appears to be due to its ability to exacerbate the intracellular production of superoxide radicals.
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267
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268
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LAMBERT GRANTR, SMITH GEOFFREYD. THE HYDROGEN METABOLISM OF CYANOBACTERIA (BLUE-GREEN ALGAE). Biol Rev Camb Philos Soc 1981. [DOI: 10.1111/j.1469-185x.1981.tb00360.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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269
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Abstract
The highly pulmonary concentration of 1,2-dipalmitoyl-sn-glycerol-3-phosphorylcholine (dipalmitoyllecithin) and its implication as an important component of lung surfactant have promoted investigation of phospholipid metabolism in the lung. This review will set the contents including recent informations for better understanding of phospholipid metabolism of the lung in normal state (physiological significances of lung phospholipids, characteristics of phospholipids in lung tissue and alveolar washing, biosynthetic pathways of dipalmitoyllecithin, etc.) as well as in toxic states (pulmonary oxygen toxicity, etc.) and in diseased states (idiopathic respiratory distress syndrome, pulmonary alveolar proteinosis, etc.) Since our main concern has been to clarify the most important route for supplying dipalmitoyllecithin, this review will be focused upon the various biosynthetic pathways leading to the formation of different molecular species of lecithin and their potential significance in the normal, toxic, and diseased lungs.
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270
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Mass spectrometric studies of hydrazine photooxidation by illuminated chloroplasts. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1981. [DOI: 10.1016/0005-2728(81)90212-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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271
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273
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Beretta C, Fadini L, Montesissa C, Pompa G, Stoppani E. Membrane lipid composition of subcellular fractions from lungs of rats treated with paraquat. PHARMACOLOGICAL RESEARCH COMMUNICATIONS 1981; 13:433-42. [PMID: 7291277 DOI: 10.1016/s0031-6989(81)80070-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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274
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Brigelius R, Hashem A, Lengfelder E. Paraquat-induced alterations of phospholipids and GSSG-release in the isolated perfused rat liver, and the effect of SOD-active copper complexes. Biochem Pharmacol 1981; 30:349-54. [PMID: 7213421 DOI: 10.1016/0006-2952(81)90065-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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275
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276
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Wold E, Kaalhus O, Johansen ES, Ekse AT. The electron affinity of some radiotherapeutic agents used in cancer therapy. INTERNATIONAL JOURNAL OF RADIATION BIOLOGY AND RELATED STUDIES IN PHYSICS, CHEMISTRY, AND MEDICINE 1980; 38:599-611. [PMID: 6970730 DOI: 10.1080/09553008014551441] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In order to evaluate whether chemotherapeutic compounds applied in cancer treatment might interact with radiation as anoxic cell sensitizers, the electron-affinic properties of DTIC, AIC, hydroxyurea, busulfan and cyclophosphamide were studied by pulse radiolysis. Reaction rates with hydrated electrons were determined for all these compounds. With the exception of DTIC, they all reacted much more slowly with electrons than do most electron-affinic sensitizers. One-electron reduction potentials were determined for DTIC, AIC and hydroxyurea. The values were all in the region for the onset of sensitization, with hydroxyurea as the most promising (E71 =- 0.0552V). For busulfan and cyclophosphamide no value could be determined, but these compounds are probably less electron-affinic than hydroxyurea. A possible application of chemotherapeutic agents as radiosensitizers is discussed.
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277
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Cadenas E, Arad ID, Fisher AB, Boveris A, Chance B. Hydroperoxide-induced chemiluminescence of the perfused lung. Biochem J 1980; 192:303-9. [PMID: 7305901 PMCID: PMC1162335 DOI: 10.1042/bj1920303] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Light-emission of the perfused lung is induced by t-butyl hydroperoxide, giving chemiluminescence yields that oscillate between 800 and 1500 counts/s depending on the site and position of the lung. The response of the perfused lung to infusion with different hydroperoxides gives a pattern similar to that observed with the liver microsomal fraction; ethyl hydroperoxide shows a much higher chemiluminescence yield than the tertiary (t-butyl and cumene)hydroperoxides. Alveolar oedema affected the light-emission of the perfused lung depending on the time at which oedema developed, decreasing light emission on infusion of hydroperoxide in the oedematous lung and increasing it when oedema appeared after the maximal chemiluminescence yield was already achieved. Paraquat, administered in vivo, augmented light-emission by approximately 2-fold. The effect of paraquat was a time-dependent process. Lung chemiluminescence, compared with liver chemiluminescence, needed higher hydroperoxide concentration to induce light-emission.
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278
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Rat alveolar macrophages require NADPH for superoxide production in the respiratory burst. Effect of NADPH depletion by paraquat. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(18)43474-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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279
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Boyd MR. Biochemical mechanisms in chemical-induced lung injury: roles of metabolic activation. Crit Rev Toxicol 1980; 7:103-76. [PMID: 6773721 DOI: 10.3109/10408448009037487] [Citation(s) in RCA: 217] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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280
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Land E. Pulse radiolysis and flash photolysis: some applications in biology and medicine. Biochimie 1980; 62:207-21. [DOI: 10.1016/s0300-9084(80)80395-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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281
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Burk RF, Lawrence RA, Lane JM. Liver necrosis and lipid peroxidation in the rat as the result of paraquat and diquat administration. Effect of selenium deficiency. J Clin Invest 1980; 65:1024-31. [PMID: 7364936 PMCID: PMC371432 DOI: 10.1172/jci109754] [Citation(s) in RCA: 185] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Paraquat and diquat facilitate formation of superoxide anion in biological systems, and lipid peroxidation has been postulated to be their mechanism of toxicity. Paraquat has been shown to be more toxic to selenium-deficient mice than to controls, presumably as the result of decreased activity of the selenoenzyme glutathione peroxidase. The present study was designed to measure lipid peroxidation and to assess toxicity in control and selenium-deficient rats given paraquat and diquat. Lipid peroxidation was measured by determining ethane production rates of intact animals; toxicity was assessed by survival and by histological and serum enzyme evidence of liver and kidney necrosis. Paraquat and diquat were both much more toxic to selenium-deficient rats than to control rats. Diquat (19.5 mumol/kg) caused rapid and massive liver and kidney necrosis and very high ethane production rates in selenium-deficient rats. The effect of paraquat (78 mumol/kg) was similar to that of diquat but was not as severe. Acutely lethal doses of paraquat (390 mumol/kg) and diquat (230 mumol/kg) in control rats caused very little ethane production and no evidence of liver necrosis. These findings suggest that paraquat and diquat exert their acute toxicity largely through lipid peroxidation in selenium-deficient rats. Selenium deficiency had no effect on superoxide dismutase activity in erythrocytes or in 105,000 g supernate of liver or kidney. Glutathione peroxidase, which represents the only well-characterized biochemical function of selenium in animals, was dissociated from the protective effect of selenium against diquat-induced lipid peroxidation and toxicity by a time-course study in which selenium-deficient rats were injected with 50 mug of selenium and later given diquat (19.5 mumol/kg). Within 10 h, the selenium injection provided significant protection against diquat-induced lipid peroxidation and mortality even though this treatment resulted in no rise in glutathione peroxidase activity of liver, kidney, lung, or plasma at 10 h. This suggests that a selenium-dependent factor in addition to glutathione peroxidase exists that protects against lipid peroxidation.
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282
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Enhancement of mitochondrial, cyanide-resistant superoxide dismutase in the livers of rats treated with 2,4-dinitrophenol. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)86140-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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283
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284
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Youngman RJ, Dodge AD, Lengfelder E, Elstner EF. Inhibition of paraquat phytotoxicity by a novel copper chelate with superoxide dismutating activity. EXPERIENTIA 1979; 35:1295-6. [PMID: 499403 DOI: 10.1007/bf01963967] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
A chelate with superoxide dismutase activity, D-penicillamine copper complex, was shown to inhibit paraquat toxicity in flax cotyledons (Linum usitatissimum var. Reina). Paraquat-stimulated chlorophyll loss and ethane production were markedly reduced by this complex. The role of superoxide in the action of paraquat is briefly discussed.
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285
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Bonfils C, Saldana JL, Debey P, Maurel P, Balny C, Douzou P. Fast photochemical reactions of cytochrome P450 at subzero temperatures. Biochimie 1979; 61:681-7. [PMID: 497255 DOI: 10.1016/s0300-9084(79)80166-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Several reactions of the cytochrome P450 multi-step cycle have been studied by fast light activation combined with subzero temperatures. A flash device was adapted to an Aminco-Chance DW 2 spectrophotometer equipped for subzero temperature thermostatisation. The first electron can be introduced into the cycle by non specific reducing agents such as reduced flavin mononucleotide (FMNH2) or methylviologen radical (MV.). This first reduction remains a fast process even at subzero temperatures. The oxy-compound Fe2+-O2 can thus be formed either directly from Fe2+ or via the photodissociation of the carboxy-ferro adduct. Fe2+-O2 is stable at subzero temperatures towards spontaneous autoxidation as well as further reduction by FMNH2 or MW.. In addition, the recombination of CO after flash photodissociation of Fe2+-CO was used to study in more details the specific behaviors of the purified microsomal cytochrome.
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286
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Debey P, Land EJ, Santus R, Swallow AJ. Electron transfer from pyridinyl radicals, hydrated electrons, CO2.- and O2.- to bacterial cytochrome P450. Biochem Biophys Res Commun 1979; 86:953-60. [PMID: 219865 DOI: 10.1016/0006-291x(79)90210-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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291
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Halliwell B. The chloroplast at work. A review of modern developments in our understanding of chloroplast metabolism. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1979; 33:1-54. [PMID: 415334 DOI: 10.1016/0079-6107(79)90024-5] [Citation(s) in RCA: 79] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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292
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Ross JH, Lim LO, Krieger RI. Herbicidal potency of 1,1'-alkyl-4,4'-bipyridylium salts as a function of their physicochemical constants in duckweed. Drug Chem Toxicol 1979; 2:193-205. [PMID: 546622 DOI: 10.3109/01480547908998242] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Duckweed (Spirodela oligorrhiza, Kurz) is a sensitive indicator of 1,1'-alkyl-4,4'-bipyridylium salt (viologen) herbicidal potency. A homologous series of viologens were tested to determine relative herbicidal potency which was related to alkyl inductive and steric effects of N-alkyl side chains. Chlorosis was assessed after 48 hr of continuous illumination to establish herbicidal potency. Herbicidally effective concentrations were 2.7, 12, 236, 71, 31, 51, 13 and 43 microM for methyl (paraquat), propyl, isopropyl, butyl, methyl-pentyl, hexyl, octyl and benzyl viologen, respectively. A biphasic relationship of herbicidal potency versus steric effect was established in which compounds with the least bulky side chains were most phytotoxic. Comparison of rat lethality (acute, subcutaneous) and herbicidal potency of these compounds indicates that none of the viologens tested are less toxic to mammals than plants compared to the commercial herbicide methyl biologen (paraquat).
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293
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Hassan H, Fridovich I. Superoxide radical and the oxygen enhancement of the toxicity of paraquat in Escherichia coli. J Biol Chem 1978. [DOI: 10.1016/s0021-9258(17)34373-9] [Citation(s) in RCA: 139] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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294
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Asada K, Nakano Y. AFFINITY FOR OXYGEN IN PHOTOREDUCTION OF MOLECULAR OXYGEN AND SCAVENGING OF HYDROGEN PEROXIDE IN SPINACH CHLOROPLASTS. Photochem Photobiol 1978. [DOI: 10.1111/j.1751-1097.1978.tb07040.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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295
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Smith LL, Rose MS, Wyatt I. The pathology and biochemistry of paraquat. CIBA FOUNDATION SYMPOSIUM 1978:321-41. [PMID: 38952 DOI: 10.1002/9780470715413.ch18] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
After the administration of paraquat to rats the lung is the organ most severely damaged. The pathology in the lung can be divided into two distinct phases: (1) a destruction phase lasting a few days with damage to the type I and type II alveolar epithelial cells, oedema and haemorrhage (most of the rats which die after dosing with paraquat do so during this phase); (2) a reparative phase with regeneration of the epithelium and, in areas of severe damage, a characteristic proliferation of fibroblasts. In both phases of the lesion the death of the rats results from anoxia. Paraquat is selectively accumulated by the rat lung in comparison with other tissues and this accounts, at least in part, for the specific toxic effect in this organ. The accumulation into the lung was shown by in vitro studies to depend on energy and is inhibited by various endogenous and exogenous compounds. This uptake process is not that which has been described for 5-hydroxytryptamine and evidence is presented to suggest that the type I and type II alveolar epithelial cells are sites of accumulation. When paraquat is present in lung cells, it undergoes a cyclical reduction and oxidation with the production of superoxide anion. This radical may lead directly or indirectly to the formation of lipid peroxides and hence to cell death. However, paraquat stimulates the pentose-phosphate pathway and both reduces the level of NADPH and inhibits fatty acid synthesis in the lung. These effects occur when there is only minimal ultrastructural damage to the lung cells. It is suggested, therefore, that the primary mechanism of toxicity of paraquat is the extreme oxidation of NADPH which inhibits vital physiological processes and renders the cell more susceptible to attack from lipid hydroperoxides.
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Smith EA, Mayfield CI. Effects of paraquat on selected microbial activities in soil. MICROBIAL ECOLOGY 1977; 3:333-343. [PMID: 24233669 DOI: 10.1007/bf02010740] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Paraquat, applied as Gramoxone, to a nonamended sandy loam soil at five times the suggested field application rate (10 lb/A ≈ 115μg/cm(2)) increased the numbers of bacteria, actinomycetes, and fungi during a 14-day incubation at 25°C. This increase was attributed to the use of compounds in the Gramoxone formulation rather than the use of paraquat. Treatment at one and five times the normal rate reduced CO2 evolution by 44% and 67%, respectively, in soil amended with 2% glucose during a 12-day incubation. Similar treatments reduced CO2 evolution in 1% straw-amended soil by 39% and 58%, respectively, during a 28-day incubation. Cellulose decomposition of cotton duck containing 13 and 176μg of paraquat per milligram of material was inhibited for 15 and 28 days, respectively, in soil containing a large population of cellulolytic microorganisms. A concentration of 5000μg/gm of paraquat was necessary to inhibit nitrification in soil by 44% druing a 28-day incubation at 20°C. Paraquat inhibited C2H2 reduction in artificial aggregates of soil amended with 2% glucose and incubated anaerobically at 25°C. Nitrogenase activity in aggregates was inhibited by 43% and 52% at concentrations of 580 and 720μg/gm of paraquat respectively. The inhibitory effects of the herbicide were reduced when soil was amended with organic matter in the form of peat or straw. The availability of paraquat controlled the toxicity of the herbicide to soil microorganisms.
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Affiliation(s)
- E A Smith
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
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298
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Anderson RF, Patel KB. Radiosensitization of Serratia marcescens by bipyridinium compounds. INTERNATIONAL JOURNAL OF RADIATION BIOLOGY AND RELATED STUDIES IN PHYSICS, CHEMISTRY, AND MEDICINE 1977; 32:471-9. [PMID: 336568 DOI: 10.1080/09553007714551231] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Bipyridinium compounds (viologens) have been shown to radiosensitize hypoxic Serratia marcescens cells by two components. These can be separated on the basis that only the one-electron reduced form of the compounds can penetrate the bacterium cell wall. One component is associated with sensitization at the membrane and the other with an internal site. The efficiency of sensitization at the membrane-associated site follows the order of increasing one-electron reduction potentials of the compounds. The one-electron reduced forms of the bipyridinium compounds are involved in a mechanism that reduces the initial level of sensitization. No additivity in sensitization is found on combining the bipyridinium compounds with other radiosensitizers, PNAP and Ro 07-0582 at concentrations of each, which will give sensitization to the level associated with the membrane site. It is concluded that all these electron-affinic compounds sensitize this site. The protective effect of added glycerol on sensitization by viologens is related to protection at the membrane-associated site.
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Witschi H, Kacew S, Hirai KI, Côté MG. In vivo oxidation of reduced nicotinamide-adenine dinucleotide phosphate by paraquat and diquat in rat lung. Chem Biol Interact 1977; 19:143-60. [PMID: 22404 DOI: 10.1016/0009-2797(77)90027-8] [Citation(s) in RCA: 79] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intravenous injection of rats with 156 mumol/kg of paraquat or 140 mumol/kg of diquat produced, within 60 min, a sharp drop in the ratios of NADPH to NADP in lung. The effect persisted for a time period of at least 24 h. Exposure to 100% oxygen enhanced the toxicity of both compounds without substantially amplifying changes in the NADPH/NADP ratio. Lungs retained the capability to synthesize adenine nucleotides de novo. Electron microscopic studies showed that both paraquat and diquat damage type I alveolar cells, but only paraquat produces type II cell lesions. Although bipyridylium herbicides produce acute oxidation of NADPH in vivo, there seems not to exist a straightforward relationship between this event and cell damage.
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Hassan H, Fridovich I. Regulation of the synthesis of superoxide dismutase in Escherichia coli. Induction by methyl viologen. J Biol Chem 1977. [DOI: 10.1016/s0021-9258(17)41019-2] [Citation(s) in RCA: 190] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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