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At least 1,711 records · Page 95Linked to original sources
PubMed1994

Concanavalin A-bound selenoprotein in human serum analyzed by graphite furnace atomic absorption spectrometry.

We developed an assay for the direct determination of selenium in serum with a Perkin-Elmer Model 4100ZL Zeeman atomic absorption spectrometer and Ag-Cu-Mg modifier. We used this assay to analyze concanavalin A-bound selenoprotein (CABSP) in human serum after concanavalin A (ConA) affinity chromatography. The CABSP was identified as a single-chain glycoprotein of 57.3 kDa. Carbohydrate units were N- and O-linked to the protein. The selenium moiety was selenocysteine. Total selenium, glutathione peroxidase (GPX; EC 1.11.1.9), ConA-bound selenium (CABS), and alpha 1-acid glycoprotein (AAG) were determined in normal subjects and patients with various pathological conditions. CABS accounted for 44.1% +/- 6.3% of total selenium in sera from normal subjects and 46.5% +/- 3.9% to 55.1% +/- 8.1% in sera from patients with a variety of diseases. Total selenium in serum was well correlated with serum CABS (r = 0.860), but not with serum GPX activity (r = 0.117), for all patients studied. Serum CABS increased in normal subjects after selenium supplementation. Serum CABSP did not behave as an acute-phase reactant, compared with AAG.

Adult↗
PubMedDate not supplied

The measurement of cadmium in biological materials, using graphite furnace atomic absorption spectrometry with Zeeman background correction.

Cadmium (Cd), a toxic heavy metal and probable carcinogen in humans, appears to have potential anti-cancer activity in pre-clinical systems. This observation led us to develop a method for measuring cellular Cd and DNA-bound Cd following micromolar exposures to cadmium dichloride. Cultured human ovarian cancer cell lines were used. Following low level exposures to cadmium dichloride (CdCl2), atomic absorption spectrometry with Zeeman background correction was used to measure total cell associated Cd in wet-ashed cells, and the lower limits of detection was at 100 pg of Cd per 106 cells. In cellular DNA isolated by cesium chloride density gradient centrifugation, levels of 1.5 Cd lesions (Cd molecules) per 106 nucleotides were reproducibly detected. Standard curves with samples yielded 76.4 6.7% recovery when using picogram quantities of Cd. Manipulation of the total amount of biological material used, can further improve detection limits. Thus, this method is suitable for the detection of Cd in biological matrixes after low levels of Cd exposure, and shows good performance in terms of the level of sensitivity and reproducibility.

Cadmium↗
PubMed2003

Improved fuel cell and electrode designs for producing electricity from microbial degradation.

A new one-compartment fuel cell was composed of a rubber bunged bottle with a center-inserted anode and a window-mounted cathode containing an internal, proton-permeable porcelain layer. This fuel cell design was less expensive and more practical than the conventional two-compartment system, which requires aeration and a ferricyanide solution in the cathode compartment. Three new electrodes containing bound electron mediators including a Mn(4+)-graphite anode, a neutral red (NR) covalently linked woven graphite anode, and an Fe(3+)-graphite cathode were developed that greatly enhanced electrical energy production (i.e., microbial electron transfer) over conventional graphite electrodes. The potentials of these electrodes measured by cyclic voltametry at pH 7.0 were (in volts): +0.493 (Fe(3+)-graphite); +0.15 (Mn(4+)-graphite); and -0.53 (NR-woven graphite). The maximal electrical productivities obtained with sewage sludge as the biocatalyst and using a Mn(4+)-graphite anode and a Fe(3+)-graphite cathode were 14 mA current, 0.45 V potential, 1,750 mA/m(2) current density, and 788 mW/m(2) of power density. With Escherichia coli as the biocatalyst and using a Mn(4+)-graphite anode and a Fe(3+)-graphite cathode, the maximal electrical productivities obtained were 2.6 mA current, 0.28 V potential, 325 mA/m(2) current density, and 91 mW/m(2) of power density. These results show that the amount of electrical energy produced by microbial fuel cells can be increased 1,000-fold by incorporating electron mediators into graphite electrodes. These results also imply that sewage sludge may contain unique electrophilic microbes that transfer electrons more readily than E. coli and that microbial fuel cells using the new Mn(4+)-graphite anode and Fe(3+)-graphite cathode may have commercial utility for producing low amounts of electrical power needed in remote locations.

Biodegradation, Environmental↗