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Biomedical subjects

J C Chapman

Publications and source records attributed to J C Chapman.

44 records · Page 3Linked to original sources
PubMed1977

Stereochemistry of olefinic bond formation in defensive steroids of Acilius sulcatus (Dytiscidae).

The defensive secretion of Acilius sulcatus contains a number of pregnane derivates: cortexone, 20alpha-hydroxy-4-pregnen-3-one, together with the unusual delta4,6 dienes, 6,7-dehydrocortexone, 20alpha-hydroxy-4,6-pregnadien-3-one and 4,6-pregnadien-3,20-dione. The synthesis of all these steroids except cortexone is described. Complete separation of the steroids of Acilius can be achieved by high-performance liquid chromatography on the reversed-phase column system. During biosynthesis of the Acilius steroids from cholesterol, introduction of the delta4 and delta6 bonds involves elimination of the 4beta and 7beta hydrogens, respectively. Possible mechanisms of formation of the delta4,6 steroids are discussed.

Animals↗
PubMed1976

Lupus erythematosus latex tests compared with the immunofluorescence method for antinuclear factor.

Two commercially available lupus erythematosus (LE) latex tests were compared against positive antinuclear antibody (ANF) sera of known titers. The Lederle SLE Latex Test Kit was found to be more specific and relatively more sensitive, particulary with high ANF titers, than the Hyland LE Test Kit. The latex test is a rapid, simple method which, when positive, can be suggestive of systemic lupus erythematosus (SLE) or other collagen disease. However, at present this test cannot replace the immunofluorescence method for detecting ANF. Where there is any clinical suggestion of SLE or a related condition, all negative results should be tested by immunofluorescence methods.

Antibodies, Antinuclear↗
PubMedDate not supplied

The DNA sequence and comparative analysis of human chromosome 20.

The finished sequence of human chromosome 20 comprises 59,187,298 base pairs (bp) and represents 99.4% of the euchromatic DNA. A single contig of 26 megabases (Mb) spans the entire short arm, and five contigs separated by gaps totalling 320 kb span the long arm of this metacentric chromosome. An additional 234,339 bp of sequence has been determined within the pericentromeric region of the long arm. We annotated 727 genes and 168 pseudogenes in the sequence. About 64% of these genes have a 5' and a 3' untranslated region and a complete open reading frame. Comparative analysis of the sequence of chromosome 20 to whole-genome shotgun-sequence data of two other vertebrates, the mouse Mus musculus and the puffer fish Tetraodon nigroviridis, provides an independent measure of the efficiency of gene annotation, and indicates that this analysis may account for more than 95% of all coding exons and almost all genes.

Animals↗
PubMedDate not supplied

Profenofos residues in wild fish from cotton-growing areas of New South Wales, Australia.

The organophosphorus (OP) pesticide profenofos (O-4-bromo-2-chlorophenyl O-ethyl S-propyl phosphorothioate) is used heavily in cotton-growing areas of eastern Australia toward the end of the growing season. European carp (Cyprinus carpio), bony bream (Nematalosa erebi), and mosquitofish (Gambusia holbrooki) were collected from the cotton-growing areas around Wee Waa, New South Wales, to determine the relationship between profenofos residues and acetyl-cholinesterase (AChE) activity in wild fish. Profenofos concentrations in water, sediment, and fish tissue reflected its general level of use; levels in March 1994 were significantly higher than in 1993 and generally decreased in May, 6 wk after cessation of spraying. Residues in carp and bony bream generally correlated with concentrations in water and sediment, although residues in fish tend to persist longer at some sites. Acetylcholinesterase inhibition was a useful indicator of profenofos exposure within a season, particularly if linked with residue measurements. Bony bream and gravid female mosquitofish recovered AChE levels more slowly than carp or nongravid mosquitofish. Recovery in creeks was generally more rapid than in lagoons.

Acetylcholinesterase↗