Biomedical subjects

S W Dixon

Publications and source records attributed to S W Dixon.

3 recordsLinked to original sources

PubMed1984

A multiconcentration controlled test atmosphere system for calibration studies.

A novel controlled test atmosphere system was developed to generate multiple concentrations of gases and vapors simultaneously. It was used successfully to study the effectiveness of two air monitoring methods to analyze for various organic compounds. Three concentrations were generated simultaneously to determine the methods' performance. This was accomplished in a single run, requiring one day, greatly improving validation efficiency. Prior to development of this system, a separate test run was required at each concentration requiring three days. Essential elements of the system include: dynamic serial dilution of the air stream to produce three concentrations; all inert surface construction (Teflon, glass, and stainless steel); diffusion/permeation tube generation with multicompound capability; low pressure drop by use of large tubing and low pressure differential mass flow meters.

Air Pollutants↗

PubMed1983

Seasonal effects on concentrations of monomethylformamide in urine samples.

Eleven du Pont operators participated in a special dimethylformamide metabolite (monomethylformamide, MMF) urine monitoring study to investigate a possible seasonal influence on urine metabolite concentrations. Variables considered included urine volume, MMF concentration, MMF mass, urine specific gravity, and ambient temperature. Statistical analysis revealed a 13% reduction in urine volume under hot weather conditions as a cause of increased MMF concentrations. A correction for this change in urine volume should be made subjectively.

Dimethylformamide↗

PubMedDate not supplied

Isolation and nucleotide sequence of the 5-aminolevulinate synthase gene from Aspergillus nidulans.

The structural gene for 5-aminolevulinate (ALA) synthase has been cloned and sequenced from the filamentous fungus Aspergillus nidulans using an oligonucleotide probe based on a highly conserved-amino-acid sequence found in ALA synthase genes of a wide range of species. The cloned gene, hemA, has a 5' untranslated mRNA of 92 nucleotides (nt) and one intron (64 nt). The deduced protein sequence (648 amino acids) shows 64% identity to the yeast ALA synthase in the C-terminal region of 453 amino acids. The N-terminal region is typical of ALA synthase proteins in that the specific amino-acid sequence is not conserved but consists of a "leader" region rich in basic amino acids, believed to be involved in mitochondrial targeting, followed by a stretch of largely hydrophobic residues which may allow interaction with the inner mitochondrial membrane. Under the conditions used the transcription of hemA was unaffected by dextrose repression, heat shock, or oxygen levels.

5-Aminolevulinate Synthetase↗