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Biomedical subjects

K Williams

Publications and source records attributed to K Williams.

At least 235 records · Page 13Linked to original sources
PubMed1996

Awareness is the cure.

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Acquired Immunodeficiency Syndrome↗
PubMed1996

A sensitive color ELISA for detecting polycyclic aromatic hydrocarbon-DNA adducts in human tissues.

Human exposure to polycyclic aromatic hydrocarbons (PAHs) has been determined by measurement of DNA adducts in human tissues. Competitive enzyme-linked immunosorbent assays (ELISAs) using antisera recognizing benzo[a]pyrenediol-epoxide-modified DNA (BPDE-I-DNA) and color of fluorescence endpoint detection have been used extensively for quantifying PAH-DNA adducts. The fluorescence ELISA (limit of detection 1 adduct/10(8) nucleotides) was previously reported to be more sensitive than the color ELISA (1/10(7)) for measuring PAH adducts (Santella et al. (1988) Carcinogenesis, 9, 1265-1269). However, the fluorescence assay has the disadvantages of greater variation among the replicates and higher background levels than the color assay. Using a newly developed antiserum against BPDE-I-DNA, we have modified the color of ELISA so that it has the same sensitivity as the fluorescence ELISA and requires only 33% of the sample quantity needed for the fluorescence ELISA. The modifications included preincubation of the antiserum with the samples, using microtiter plates with half-size, flat bottom wells, and optimizing the assay conditions. The improved color ELISA was used to analyze DNA samples from human autopsy tissues, including heart, lung, liver, kidney, spleen, pancreas and stomach from smokers and nonsmokers. With the exception of spleen and stomach, all tissues from smokers showed higher PAH-DNA adducts (ranging from 0.3 to 19.0 adducts/10(7) nucleotides) than the tissues from the nonsmokers (0.3 to 3.7 adducts/10(7) nucleotides) in two separate experiments. Among the tissues from smokers, heart showed the highest level of DNA adducts. This study demonstrates that a stable color ELISA with high sensitivity can be useful in assessing human exposure to PAH.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1996

Handle with care.

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Biomechanical Phenomena↗
PubMed1996

Two-dimensional electrophoresis of human urinary proteins following concentration by dye precipitation.

The use of dye precipitation for concentration of proteins prior to 2-DE has been demonstrated by application to human urine. The precipitation methods (T. Marshall and K. M. Williams, Clin. Chem. 1993, 39, 2314-2318; T. Marshall et al., Electrophoresis 1995, 16, 28-31) have been adapted for two-dimensional electrophoresis (2-DE) by modifying the reagent composition and adding sodium dodecyl sulphate (SDS) to the assay mixture. These modifications extend the precipitation range of the methods and overcome the problem of soluble glycoprotein-dye complexes. The protein-dye complex is recovered by centrifugation and dissolved in a small volume of sample denaturing buffer. The dye separates from the protein on 2-DE (forming a sharp band at the anodal end of the isoelectric focusing gel) so that the positional coordinates of the polypeptides are unaffected by the treatment. Dye precipitation provides a simple, rapid and highly economic method for concentrating urines of low to intermediate protein content (0.02-0.50 g/L) prior to 2-DE analysis.

Animals↗
PubMed1996

Removal of Cr(VI) from ground water by Saccharomyces cerevisiae.

Chromium can be removed from ground water by the unicellular yeast, Saccharomyces cerevisiae. Local ground water maintains chromium as CrO42- because of bicarbonate buffering and pH and Eh conditions (8.2 and +343 mV, respectively). In laboratory studies, we used commercially available, nonpathogenic S. cerevisiae to remove hexavalent chromium [Cr(VI)] from ground water. The influence of parameters such as temperature, pH, and glucose concentration on Cr(VI) removal by yeast were also examined. S. cerevisiae removed Cr(VI) under aerobic and anaerobic conditions, with a slightly greater rate occurring under anaerobic conditions. Our kinetic studies reveal a reaction rate (Vmax) of 0.227 mg h-1 (g dry wt biomass)-1 and a Michaelis constant (Km) of 145 mg/l in natural ground water using mature S. cerevisiae cultures. We found a rapid (within 2 minutes) initial removal of Cr(VI) with freshly hydrated cells [55-67 mg h-1 (g dry wt biomass)-1] followed by a much slower uptake [0.6-1.1 mg h-1 (g dry wt biomass)-1] that diminished with time. A materials-balance for a batch reactor over 24 hours resulted in an overall shift in redox potential from +321 to +90 mV, an increase in the bicarbonate concentration (150-3400 mg/l) and a decrease in the Cr(VI) concentration in the effluent (1.9-0 mg/l).

Aerobiosis↗