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19 results on '"Foster, A.L."'

7. X-ray absorption fine-structure spectroscopy study of photocatalyzed, heterogenous AS(III) oxidation on kaolin and anatase

Author

Foster, A.L., Brown, G.E., Jr., and Parks, G.A.

Subjects
Arsenic -- Environmental aspects, Bioremediation -- Research, Titanium -- Environmental aspects, Environmental issues, Science and technology
Abstract

An investigation into the photocatalyzed absorption of arsenic(As)(III) on such substrates as kaolin, smectite, anatase, gibbsite and amorphous silica showed over 30% of the As(III) being oxidized to As(V) using kaolin and anatase, while only 10% of the As(III) was oxidized using gibbsite and smectite. Titanium in both kaolin and anatase is believe to be responsible for accelerating the arsenic oxidation process.

Published
1998

8. A Focus on Chemical and Microbial Processes at Environmental Interfaces

Author

Brown, Jr-G.E., Nilsson, A., Spormann, A.M., P. Addiego, W., Benzerara, K., Bergmann, U., Bluhm, H., A. Brown, B., Calas, G., Chaka, A.M, Constantz, B.R., Farges, F., E. Fendorf, S., Foster, A.L., Juillot, F., Morin, G., S.C.B., M., Pettersson, L.G.M., Rosso, K.M., Rytuba, J.J., Salmeron, M., Saltzman, J., Toney, M., Trainor, T.P., Yoon, T., Institut de minéralogie et de physique des milieux condensés (IMPMC), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), and Université Pierre et Marie Curie - Paris 6 (UPMC)-IPG PARIS-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2006

10. X-ray absorption fine-structure spectroscopy study of photocatalyzed, heterogeneous as (III)...

Author

Foster, A.L., Brown Jr., G.E., and Parks, G. A.

Subjects
*OXIDATION, *KAOLIN, *TITANIUM dioxide
Abstract

Presents a study which investigated photocatalyzed, heterogeneous As(III) oxidation on kaolin and anatase. Methodology used to conduct the study; Identification of the common first-row transition elements which participate in electron-transfer reactions; Effect of titanium chemical speciation on reactivity towards As(III).

Published
1998
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11. Penicillamine and penicillin can generate antigenic determinants on rat peritoneal cells <em>in vitro</em>.

Author

O'Donnell, C.A., Foster, A.L., and Coleman, J.W.

Subjects
*CELLS, *ANTIGENS, *EPITOPES, *IMMUNITY, *CHELATION therapy, *AUTOIMMUNITY
Abstract

Conjugation of the protein-reactive drugs D-penicillamine (PA) and benzylpenicillin (BP) to immune cells to generate drug-derived antigenic determinants has been implicated in drug-induced allergies and autoimmunity. We have therefore developed an in vitro system to demonstrate and characterize the formation of cellular antigens by these drugs. Binding of PA and BP to rat peritoneal exudate cells was detected by a cell ELISA, employing rabbit antisera specific for each drug, and an indicator system employing a second antibody coupled to biotin-streptavidin-β-galactosidase. For both drugs, binding was detected over the concentration range 125-1000 µg/ml. PA bound cells rapidly (maximum binding within 10 min), whereas BP bound relatively slowly (maximum binding occurring later than 4 hr). A possible role for intracellular processing and cellular metabolic activity in the generation of these drug-derived antigenic determinants was examined. Pretreatment of the cells with the fixative paraformaldehyde significantly enhanced binding of PA but not BP. Treatment of cells with the lysosomotropic agents ammonium chloride or chloroquine, or with the metabolic inactivator sodium azide, did not affect the binding of either drug compared with untreated control cells. However, treatment with the oxidising agent copper sulphate, or the cellular activator phorbol myristate acetate, did significantly enhance binding of both drugs to the cells. Therefore, binding of PA and BP to the cell surface appears not to require an intracellular processing event to generate a recognizable antigenic determinant, but is enhanced by treatments that stimulate oxidative processes. [ABSTRACT FROM AUTHOR]

Published
1991

12. Characterization of arsenic species in microbial mats from an inactive gold mine

Author

Foster, A.L. and Ashley, R.P.

Abstract

Filamentous cyanobacterial mats and Fe oxyhydroxide-rich bacterial mats collected near an inactive gold mine in California are enriched in arsenic (As) approximately 1000-fold relative to the waters in contact with them. The predominant organism in the cyanobacterial mat could not be identified using morphological characteristics, but the unique morphology of the sheath-forming β protobacterium Leptothrix ochracea was used to identify this species in Fe oxyhydroxide mat samples from several sites near the gold mine. Leptothrixsheaths commonly exceed 10 μm in length and have an average diameter of 1 μm. The Fe-oxyhydroxide mats are dominated by L. ochracea sheaths, but use of fluorescently tagged genetic stains reveals the presence of sheathless bacteria that presumably also promote the formation of Fe oxyhydroxide. X-ray absorption fine structure (XAFS) spectroscopy was used to identify As species in these microbial mats. Mat-associated As is predominantly As(V), even when As(III) is the primary dissolved species in contact with the mats. The species of As(V) associated with the cyanobacterial mat could not be conclusively identified; however, it is not associated with Fe oxyhydroxide or other minerals, based on comparison to XAFS spectra of As adsorbed to various substrates. In addition, the cyanobacterial mat XAFS spectrum is different from that of aqueous As(V), suggesting that As(V) in the mat lacks some or all of the coordinating water molecules present in aqueous solution. We hypothesize that As is associated with the exopolysaccharide (EPS) matrix secreted by the cyanobacteria. In Leptothrix-dominated Fe-oxyhydroxide bacterial mats, XAFS analysis clearly indicates that As(V) is associated with the Fe oxyhydroxide as an adsorbed and/or coprecipitated complex.

Published
2002

18. Applied geochemistry, geology and mineralogy of the northernmost Carlin trend, Nevada.

Author

Theodore T.G., Abbott E.W., Berger V.I., Foster A.L., Kotlyar B.B., Singer D.A., Theodore T.G., Abbott E.W., Berger V.I., Foster A.L., Kotlyar B.B., and Singer D.A.

Abstract

Three-dimensional element distribution models were constructed from stream-sediment, rock and drill-core geochemical data to highlight metal zoning in the mineralised systems. The Rodeo Creek deposit comprises deep Ag-mineralised rock +/- Au with Ag/Au ratio greater than 30, below a thrust fault. Stacked geochemical haloes are confined to the thrust's lower plate and include two horizons of Hg, Cu and Zn anomalies as much as 180 m above the deposit. Subtle indications of mineralisation above the thrust include arsenopyrite overgrowths on small pyrite crystals in 50-75 micrometre clay-carbonate veinlets, arsenical rims on diagenetic pyrite and partial replacement of diagenetic pyrite by tennantite, some of the minerals containing anomalous Au. The anomaly is probably not related to Rodeo Creek or the nearby Dee and Storm gold deposits but to another locus. District-scale geochemical patterns coincide with the Carlin trend and can be used to explore for Carlin-type deposits, arsenic being the best pathfinder element in all media sampled. High As and Sb contents have NW-elongate lobe patterns outlining the trend across 4 km. Factor analysis shows that factor scores correlated with As, Sb, Au and Pb are also high. Most As in stream sediments is apparently contained in light fractions., Three-dimensional element distribution models were constructed from stream-sediment, rock and drill-core geochemical data to highlight metal zoning in the mineralised systems. The Rodeo Creek deposit comprises deep Ag-mineralised rock +/- Au with Ag/Au ratio greater than 30, below a thrust fault. Stacked geochemical haloes are confined to the thrust's lower plate and include two horizons of Hg, Cu and Zn anomalies as much as 180 m above the deposit. Subtle indications of mineralisation above the thrust include arsenopyrite overgrowths on small pyrite crystals in 50-75 micrometre clay-carbonate veinlets, arsenical rims on diagenetic pyrite and partial replacement of diagenetic pyrite by tennantite, some of the minerals containing anomalous Au. The anomaly is probably not related to Rodeo Creek or the nearby Dee and Storm gold deposits but to another locus. District-scale geochemical patterns coincide with the Carlin trend and can be used to explore for Carlin-type deposits, arsenic being the best pathfinder element in all media sampled. High As and Sb contents have NW-elongate lobe patterns outlining the trend across 4 km. Factor analysis shows that factor scores correlated with As, Sb, Au and Pb are also high. Most As in stream sediments is apparently contained in light fractions.

19. Compounds that confer thermal stress resistance and extended lifespan

Author

Matthew S. Gill, Anders Olsen, Maithili C. Vantipalli, Mark P. White, Michael G. Benedetti, James N. Sampayo, Gordon J. Lithgow, Amanda L. Foster, Benedetti M.G., Foster A.L., Vantipalli M.C., White M.P., Sampayo J.N., Gill M.S., Olsen A., and Lithgow G.J.

Subjects
Aging, media_common.quotation_subject, ved/biology.organism_classification_rank.species, Longevity, Endocrine System, Disease, Biology, medicine.disease_cause, Biochemistry, Models, Biological, Antioxidants, Article, chemistry.chemical_compound, Endocrinology, Genetics, medicine, Animals, Model organism, Caenorhabditis elegans, Caenorhabditis elegans Proteins, Molecular Biology, Propyl gallate, Genes, Helminth, media_common, ved/biology, Cell Biology, biology.organism_classification, Oxidative Stress, chemistry, Trolox, Cell aging, Oxidative stress
Abstract

The observation that long-lived and relatively healthy animals can be obtained by simple genetic manipulation prompts the search for chemical compounds that have similar effects. Since aging is the most important risk factor for many socially and economically important diseases, the discovery of a wide range of chemical modulators of aging in model organisms could prompt new strategies for attacking age-related disease such as diabetes, cancer and neurodegenerative disorders [Collins, J.J., Evason, K., Kornfeld, K., 2006. Pharmacology of delayed aging and extended lifespan of Caenorhabditis elegans. Exp. Gerontol.; Floyd, R.A., 2006. Nitrones as therapeutics in age-related diseases. Aging Cell 5, 51-57; Gill, M.S., 2006. Endocrine targets for pharmacological intervention in aging in Caenorhabditis elegans. Aging Cell 5, 23-30; Hefti, F.F., Bales, R., 2006. Regulatory issues in aging pharmacology. Aging Cell 5, 3-8]. Resistance to multiple types of stress is a common trait in long-lived genetic variants of a number of species; therefore, we have tested compounds that act as stress response mimetics. We have focused on compounds with antioxidant properties and identified those that confer thermal stress resistance in the nematode Caenorhabditis elegans. Some of these compounds (lipoic acid, propyl gallate, trolox and taxifolin) also extend the normal lifespan of this simple invertebrate, consistent with the general model that enhanced stress resistance slows aging.

Published
2007

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