PubMed Health⌕ Search

Biomedical subjects

S D Burton

Publications and source records attributed to S D Burton.

13 recordsLinked to original sources
PubMed2001

Examination of cadmium(II) complexation by the Suwannee River fulvic acid using 113Cd NMR relaxation measurements.

Aquatic and terrestrial fulvic acids are environmentally important because they affect the bioavailability and transport of metal ions. Prior studies demonstrated that Cd(ll) binds to the oxygen containing functional groups of fulvic acids. The complexation of Cd(II) is further investigated in this study using 113Cd NMR relaxation measurements for solutions of the Suwannee River fulvic acid (SRFA). Spin-lattice (T1) and spin-spin (T2) relaxation times are measured over a range of Cd(II):SRFA ratios. The results clearly indicate two types of Cd(II) binding sites for the SRFA. A series of model ligands was also examined to gain further understanding of the two types of binding motifs present in the fulvic acid. The results for a model compound containing several carboxylate functionalities in near proximity correspond very closely to the results obtained for the strong binding sites of the Cd(II)-SRFA complexes.

Algorithms↗
PubMed1991

High-performance liquid chromatographic method for the determination of spectinomycin in turkey plasma.

A selective high-performance liquid chromatographic (HPLC) method with ultraviolet-visible (UV-VIS) detection was developed to measure therapeutic concentrations of spectinomycin in turkey plasma. Treatment of plasma samples with 3% trifluoroacetic acid in acetonitrile facilitated spectinomycin extraction and protein precipitation. After centrifugation, the stable derivatization reagent, 2,4-dinitrophenyl-hydrazine, was added to an aliquot of the supernatant, and the mixture was incubated for 30 min at 70 degrees C. Excess reagent was quenched with acetone and additional heating. The resulting derivative, a proposed spectinomycin-hydrazone, was separated from other compounds by reversed-phase HPLC during a short gradient run. The absorbance of the effluent was monitored spectrophotometrically with the UV-VIS detector set at 205 nm. The detector response was linear through the range of interest, 2-100 micrograms/ml.

Animals↗
PubMed1990

Occurrence of a Thiothrix sp. Attached to Mayfly Larvae and Presence of Parasitic Bacteria in the Thiothrix sp.

Larvae of the mayfly (Drunella grandis [Eaton]) from Diamond Fork Creek, Utah, were covered with a heavy growth of the sulfide-oxidizing bacterium Thiothrix. The bacterium did not seem to harm the mayfly, but the Thiothrix trichomes were parasitized by three morphologically distinct bacteria, two of which were cytoplasmic and one of which was probably periplasmic. At least two of the parasites destroyed the cytoplasmic contents of the Thiothrix sp., thus killing the host cell. Attempts to obtain the parasites in pure culture were unsuccessful.

Journal Article↗
PubMed1978

Improved enrichment and isolation procedures for obtaining pure cultures of beggiatoa.

Scoring agar surfaces with alginate swabs before placing washed filaments of Beggiatoa on the agar has greatly increased the rate at which single filaments move from contaminated areas. Numerous morphological types of pure cultures have been grown in organic media supplemented with either catalase or reducing agents. Aerated sewage was used as the enrichment source.

Journal Article↗
PubMed1977

Establishing generalization effects among autistic children.

Although elusive, generalization of behavior change in autistic children is essential to obtaining maximum treatment effects. Using behaviorally based treatment and teachers and parents as trainers, generalization effects between home and school were measured on four behaviors: following instructions, washing, wiping bottom, and sharing toys. The results indicate that both settings were effective in establishing generalization. Behaviors treated in one setting generalized to another when children were provided with an opportunity for daily practice. Treatment with practice in other settings is possible in contrast to providing treatment on the same behavior in both settings.

Adolescent↗
PubMed1976

The effects of selected gases on excystation of coccidian oocysts.

The mechanism of CO2 action in changing coccidian oocyst wall permeability was indirectly studied by substituting NO, NO2, N2O, H2S, SO2, CH4, NH3, and 8M urea in place of CO2 in an established excystation procedure. Changes in oocyst wall permeability of Eimeria stiedai, E. bovis, and E. tenella were determined by incubation in test gases and cysteine HCl followed by attempted activation of sporozoites by trypsin and bile and staining of intraoocyst components with methylene blue. The gases CH4, NO2, and N2O were negative for all 3 tests, as were SO2, NH3, and 8M urea which, in addition, were toxic to the oocysts. Both H2S and NO were capable of mimicking the action of CO2 and are related chemically to the reducing agent, and thus tend to underscore its importance in excystation. It now appears that the role of CO2 is that of an allosteric effector enhancing the action of the reducing agent.

Ammonia↗
PubMed1976

Formation of sulfhydryl groups in the walls of Eimeria stiedai and E. tenella oocysts subjected to in vitro excystation.

Eimeria stiedai or Eimeria tenella oocysts were incubated in aqueous cysteine hydrochloride (cysHCl) under carbon dioxide (CO2), aqueous cysHCl under air, water under CO2 or water under air, and analyzed for sulfhydryl (-SH) groups. The cysHCl-CO2 treatment produced more -SH groups than the other treatments and was effective in allowing activation of intact and sodium hypochlorite (NaOCl)-treated E. stiedai oocysts as well as NaOCl-treated E. tenella oocysts. The CO2-cysHCl complex may act directly on the oocyst wall, especially in the micropylar region, to unmask lipid-shielded disulfide bridges, which are reduced to -SH groups. The reduction apparently disturbs the protein superstructure of the oocyst wall, promotes opening of the micropyle, and changes the impermeable state of the sporulated oocyst.

Animals↗
PubMed1966

Utilization of acetate by Beggiatoa.

Burton, Sheril D. (Institute of Marine Science, University of Alaska, College), Richard Y. Morita, and Wayne Miller. Utilization of acetate by Beggiatoa. J. Bacteriol. 91:1192-1200. 1966.-A proposed system which would permit acetate incorporation into four-carbon compounds without the presence of key enzymes of the citric acid cycle or glyoxylate cycle is described. In this system, acetyl-coenzyme A (CoA) is condensed with glyoxylate to form malate, which, in turn, is converted to oxaloacetate. Oxaloacetate then reacts with glutamate to produce alpha-ketoglutarate, which is subsequently converted to isocitrate. Cleavage of isocitrate produces glyoxylate and succinate. Thus, the proposed system is similar to the glyoxylate bypass in that malate is produced from glyoxylate and acetyl-CoA, but differs from both the citric acid cycle and the glyoxylate bypass, since citrate and fumarate are not involved. Fumarase, aconitase, catalase, citritase, pyruvate kinase, enolase, phosphoenolpyruvate carboxylase, lactic dehydrogenase, alpha-ketoglutarate dehydrogenase, and condensing enzyme were not detectable in crude extracts of Beggiatoa. Succinate was oxidized by a soluble enzyme not associated with an electron-transport particle. Isocitrate was identified as the sole compound labeled when C(14)O(2) was added to a reduced nicotinamide adenine dinucleotide, CO(2) generating system (crystalline glucose-6-phosphate dehydrogenase and glucose-6-phosphate) in the presence of alpha-ketoglutarate.

Acetates↗