摘要:

AbstractArsenic is ubiquitous in the environment. Although the average arsenic concentrations in rocks (∼2 mg kg−1), soils (∼2 mg kg−1), freshwater (∼1 m̈g dm−3), seawater (∼2 m̈g dm−3) and organisms is generally low, high arsenic concentrations in limited areas are not uncommon. Whereas terrestrial organisms appear not to accumulate arsenic, marine organisms effectively concentrate arsenic to levels thousand of times higher than in ocean waters. The geochemical cycle and mineralogy of arsenic are reviewed with some emphasis towards Japanese locations and arsenic concentrations (averages, ranges) found in samples from the lithosphere, pedosphere, hydrosphere and biosphere are tabula

ISSN:0268-2605    

DOI:10.1002/aoc.590020403

出版商:Longman Group UK Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractTrimethyl(carboxymethyl)arsonium zwitterion (arsenobetaine) is virtually ubiquitous in marine animals consumed by man. Experimental work on the transformation of arsenate to arsenobetaine in the marine environment is reviewed. Current evidence favors the conversion of arsenate to dimethyl(ribosyl)arsine oxides by algae, and the microbially mediated transformation of dimethyl(ribosyl)arsine oxides to arsenobetaine or to its immediate precursors in the sediments. Information about the transfer of arsenobetaine from the sediments to marine animals is lacking.

ISSN:0268-2605    

DOI:10.1002/aoc.590020404

出版商:Longman Group UK Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractArsenic has a reputation as a poison, because arsenic trioxide was used during medieval times as an agent for murder. Lingering memories of these events make any arsenic‐containing material suspect. Toxicity is a property of a specific compound and varies with the composition and structure of compounds. Developments in analytical methodology made it possible not only to determine total arsenic in a variety of matrices but also arsenic compounds. Knowledge about the arsenic cycle in marine systems has expanded considerably during the past decade. The marine arsenic cycle appears to be more complex than the cycle in the terrestrial environment. More attention must be given to the minor arsenic‐containing compounds detected in organisms and experiments should be undertaken that provide information about the biochemical pathways used for the transformation of arsenic compou

ISSN:0268-2605    

DOI:10.1002/aoc.590020405

出版商:Longman Group UK Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractOne‐time oral administration of arsenic trioxide to hamsters with toxic liver cirrhosis induced by longterm exposure to carbon tetrachloride resulted in significant elevations of the concentrations of dimethylarsenic species in the liver and in blood, and in high urinary excretions of dimethylarsenic species. These concentration changes in the liver, blood and urine indicated that the methylation of inorganic arsenic was not inhibited but promoted in hamsters suffering from experimentally induced toxic liver cirrhosis. Cirrhotic hamsters also had increased urinary excretion of inorganic arsenic. Results of the determinations of S‐adenosylmethionine in the livers suggested that this compound may accelerate the methylation of inorganic arsenic in the cirrhotic li

ISSN:0268-2605    

DOI:10.1002/aoc.590020406

出版商:Longman Group UK Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe effect of giutathione (GSH) concentrations in livers and kidneys of hamsters on the toxicity and methylation of arsenite in these animals was studied. No significant changes in hepatic and renal GSH concentrations were observed after a single arsenite administration (5 mg As kg−1, p.o.). When buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, was given (4 mmol kg−1, i.p.) two hours before administration of arsenite, hepatic and renal GSH concentrations were more severely and persistently depressed than in the case of BSO administration not followed by arsenite. Hamsters treated with BSO plus arsenite suffered from severe nephrotoxicity (acute renal failure) characterized by increases in plasma creatinine and urea nitrogen and by proximal tubular necrosis. Concurrently, transient hepatotoxicity was observed in the BSO plus arsenite group. Neither arsenite alone nor BSO alone produced liver or kidney injury. The BSO plus arsenite‐treated animals excreted in the urine only 3.5% of the arsenic dose during the 72 h period after administration of arsenite, probably because of a decrease in urine volume caused by kidney injury, whereas the arsenite‐only group excreted 27%. In addition, BSO pretreatment influenced the relative proportion of arsenic metabolites excreted in the urine during the first 24 h after administration. Urinary metabolites in the BSO plus arsenite group were predominantly inorganic arsenic. These results suggest that GSH provides protection against arsenic t

ISSN:0268-2605    

DOI:10.1002/aoc.590020407

出版商:Longman Group UK Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe interaction of arsenic and selenium compounds on the metabolism of these elements in golden hamsters was studied. Golden hamsters were divided into three groups and administered sodium selenite (Na2SeO3), sodium arsenite (NaAsO2) and Na2SeO3with NaAsO2, respectively, by a single Subcutaneous injection of 25 m̈mol kg−1body weight as As or Se (arsenic and selenium were calculated as weight of elemental arsenic and selenium). Selenium and arsenic metabolites were determined by high‐performance liquid chromatography–graphite furnace atomic absorption spectrometry (HPLC–GFA AA) and gas chromatography (GC). The results show (1): About 10% by weight of the given dose of selenium was excreted in expiration air as dimethylselenide (Me2Se) during 12 h after administration of Na2SeO3. Excretion of dimethylselenide with the respiratory air was inhibited by administration of Na2SeO3simultaneously with NaAsO2. (2) Giving Na2SeO3plus NaAsO2had no appreciable effect on the excretion of the trimethylselenonium ion (Me3Se+) into the urine and the feces. (3) Giving Na2SeO3plus NaAsO2increaed the excretion into the feces of an insoluble unknown‐structure selenium compound, the proportion of which was 10.9% by weight of the given dose of selenium. (4) Giving NaAsO2plus Na2SeO3decreased the excretion of dimethylarsinic acid (Me2AsOOH) and inorganic arsenic into the urine during 120 h after the administration of the reagents, the decreased amount being 5.3% (dimethylarsinic acid) and 7.7% (inorganic arsenic) of the given dose of arsenic, respectively. (5) Giving NaAsO2plus Na2SeO3increased the excretion into feces of insoluble unknown‐structure arsenic compound and inorganic arsenic, the increased amounts being 10.6% and 7.0% of the given dose of arsenic, respectively. (6) Giving NaAsO2plus Na2SeO3decreased the excretion into feces of extractable unknown‐structure arsenic compound, and the decreased amount was 4.9% of the given dose of arsenic. (7) It made little difference to the excretion of monomethylarsonic acid [MeAsO(OH)2] into urine and feces and of dimethylarsinic acid (Me2AsOOH) into feces whether NaAsO2was administered alone o

ISSN:0268-2605    

DOI:10.1002/aoc.590020408

出版商:Longman Group UK Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractChronic toxicity, including tumorigenicity, of gallium arsenide (GaAs) and arsenic trioxide (As2O3) were studied using Syrian golden hamsters given intermittent intratracheal instillations. GaAs particles (0.25 mg × 15 times/animal) were likely to produce relatively severe lung damage and the survival of the animals was shortened significantly compared with a control group. The tumor incidence of each group examined was GaAs (3.3%), As2O3(3.3%) respectively, at a dose of 3.75 mg total metal given during 15 weeks. In this experiment, both arsenic trioxide and gallium arsenide had no apparent carcinogenicity or tumorigenicity

ISSN:0268-2605    

DOI:10.1002/aoc.590020409

出版商:Longman Group UK Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe behavior of arsenite, methylarsonic acid, dimethylarsinic acid, trimethylarsine oxide, dimethyl‐R‐arsine oxides, and trimethyl‐R‐arsonium compounds (R = carboxymethyl, 2‐carboxyethyl, 2‐hydroxyethyl) toward sodium borohydride and hot aqueous sodium hydroxide was investigated. The arsines obtained by sodium borohydride reduction of the undigested and digested solutions were collected in a liquid‐nitrogen cooled trap, separated with a gas chromatograph, and detected with a mass spectrometer in the selected‐ion‐monitoring mode. The investigated arsenic compounds were stable in hot 2 mol dm−3sodium hydroxide except arsenobetaine [trimethyl(carboxymethyl)arsonium zwitterion] that was converted to trimethylarsine oxide, and dimethyl(ribosyl)arsine oxides that were decomposed to dimethylarsinic acid. Hydride generation before and after digestion of extracts from marine organisms allowed inorganic arsenic, methylated arsenic, arsenobetaine, and ribosyl arsenic compounds to be identified and quantified. This method was applied to extracts from shellfish, fish, crusta

ISSN:0268-2605    

DOI:10.1002/aoc.590020410

出版商:Longman Group UK Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractOf the several types of arsenic metabolic pathways in algae and aquatic higher plants, production of arsenoribosides is predominant and most interesting. Insertion of the ribosyl or adenosyl moiety by transfer from S‐adenosylmethioninine or possibly from adenosylcobalamin is the critical biochemical step which, as yet, has not been experimentally demonstrated. Oceanic or other environmental arsenate (AsO43−), absorbed in the plant's quest for phosphate, is fixed by reaction with ATP to yield the phosphoric arsenic anhydride APAs, a short‐lived but reducible intermediate which is converted to arsenic(III). The Hill Reaction, or thioredoxin reductase, reduces it to an arsine oxide (HAsO) or arsonous acid [HAs(OH)2] depending upon the water content of its environment. This readily diffusible reagent avidly attacks sulfhydryl groups of proteins to produce arsonous thioesters. TheSargassumgroup of algae appears to process arsenate no further than this. The reduced arsenic may be freed from its sulfur bondage by reaction with 2,3‐dimercaptopropan‐1‐ol (BAL) or dithiothreitol. In experiments withSargassum fluitansandSargassum natansno arsenoribosides were observed. Only protein‐bound arsenic was observed. It could be liberated by trituration with dithiothreitol to produce the cyclic arsonous dithioester.Most diatoms, dinoflagellates and macroalgae as well as freshwater higher plants release such protein‐bound arsenic as a result of sequential methylation and adenosylation. Ultimately the products are trialkylarsine oxides, innocuous substances which are slowly or not‐at‐all metabolized by herbivorous animals or bacteria. Fortunately mammals and most animals also excrete the arsenoribosides readily, unchanged. Arsenic metabolism by a cyanobacterium,Phormidiumsp., was described by Matsutoet al. (Comp. Biochem. Physiol., 1984, 78c:377) as involving two modes of arsenate fixation, reduction, and excretion. We have extended those experiments withPhormidium persicinum.We have analyzed algae from 2‐ and 7‐day culture in radioarsenate media. The arsenic products included 80% of arsenolipid, similar if not identical to that formed in the brown algae. The water‐soluble products were in low concentration. Insoluble, protein‐bound arsonous thioesters accounted for 8% of the fixed arsenic. The mechanism of arsenic depuration inPhormidiumappears to

ISSN:0268-2605    

DOI:10.1002/aoc.590020411

出版商:Longman Group UK Ltd.    

年代:1988

数据来源: WILEY

摘要:

AbstractAccumulation, biomethylation and excretion of arsenic by the arsenic‐tolerant freshwater blue–green alga,Phormidiumsp., which had been isolated from an arsenic‐polluted environment, were investigated.The cellular growth curves were in fair agreement with a ‘logistic curve’ equation. The growth increased with an increase in the surrounding arsenic concentration up to 100 m̈g g−1. The cells survived even at 7000 m̈g g−1. The arsenic concentration of the cells increased with an increase of the surrounding arsenic concentration up to 7000 m̈g g−1. Phosphorus concentrations in the medium affected the growth and arsenic accumulation. No arsenic was accumulated by cells killed by ethanol.The arsenic was methylated to the extent of 3.2% of the total arsenic accumulated. When the cells were transferred into an arsenic‐free medium, 85% of the arsenic accumulated was excreted; 58% of the excreted arsenic was in methylated form implying extensive methylation in the

ISSN:0268-2605    

DOI:10.1002/aoc.590020412

出版商:Longman Group UK Ltd.    

年代:1988

数据来源: WILEY