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Biomedical subjects

D J Osborne

Publications and source records attributed to D J Osborne.

At least 19 recordsLinked to original sources
PubMed1992

Identification of o-hydroxyphenylacetaldehyde as a major metabolite of coumarin in rat hepatic microsomes.

The metabolism of [3-14C]coumarin has been studied in hepatic microsomes from control (corn-oil treated) and Aroclor 1254-treated (100 mg/kg body weight/day, 5 days, ip) rats. [3-14C]Coumarin metabolites in incubate extracts were separated by HPLC and identified by comparison with the retention times of known coumarin metabolites. The major product produced by incubation of 0.25-2.5 mM-[3-14C]coumarin with both control and Aroclor 1254-induced hepatic microsomes was a novel coumarin metabolite. This novel metabolite was extracted from pooled microsomal incubations, purified by semi-preparative HPLC and identified by mass spectrometry as o-hydroxyphenylacetaldehyde (o-HPA). Some possible pathways for the formation of o-HPA from coumarin are proposed.

Acetaldehyde↗
PubMed1992

Enterobacterial tetracycline resistance in relation to plasmid incompatibility.

Sixty-eight well-characterized antibiotic resistance (R) plasmids belonging to 19 Incompatibility groups were screened with probes representing heterologous classes (A-E) of the enterobacterial tetracycline resistance (TcR) determinant. The Class B determinant was shown to be predominant in the IncF and IncH complexes and the IncC group. The Class A determinant was shown to be predominant in the IncP and IncM groups. There was no correlation between distribution of the class of TcR gene and the genus or the species of the host bacterial strain. The plasmids R714a (IncFI) and pHH1465 (IncC) contained TcR determinants which had no homology with any of these five probes.

Enterobacteriaceae↗
PubMed1992

Cloning of a probe for a previously undescribed enterobacterial tetracycline resistance gene.

An 8.35 kb BamHI fragment was cloned from the plasmid R714a. It encoded resistances to chloramphenicol, streptomycin, spectinomycin and tetracycline. Tetracycline resistance was determined by a locus without homology to the known enterobacterial gene classes, TetA-TetE. Further subcloning of the fragment located an unusual tetracycline resistance gene on a 4.7 kb BamHI-BglII fragment. A physical-genetic map of this fragment indicated that the gene was bisected by a PstI site. Deletion analysis and insertion mutagenesis were used to define a suitable probe. An intragenic PstI-AvaI fragment of 1.2 kb was identified, and used as a non-radioactive probe, being specific for this previously undescribed enterobacterial Tet gene.

Cloning, Molecular↗
PubMed1991

The separation of chondroitin sulfate disaccharides and hyaluronan oligosaccharides by capillary zone electrophoresis.

We have developed techniques for the separation of unsulfated (2-acetamido-2-deoxy-3-O-(4-deoxy-alpha-L-threo- hex-4-enopyranosyluronicacid)-D-galactose and -D-glucose), monosulfated (2-acetamido-2-deoxy-3- O-(4-deoxy-2-O-sulfo-alpha-L-threo-hex-4-enopyranosyluronic acid)-D-galactose and 2-acetamido-2-deoxy-3-O-(4-deoxy-alpha-L-threo-hex- 4-enopyranosyluronic acid)-4-sulfo-D-galactose and -6-sulfo-D-galactose),disulfated (2-acetamido-2-deoxy-3-O-(4-deoxy-2-O-sulfo-alpha-L-threo-hex-4- enopyranosyluronic acid)-4-sulfo-D-galactose and -6-sulfo-D-galactose and 2-acet-amido-2-deoxy-3-O-(4-deoxy-alpha-L-threo-hex-4-enopy- ranosyluronic acid)-4,6-di-O-sulfo-D-galactose), and trisulfated (2-acetamido-2-deoxy-3-O-(4-deoxy-2-O- sulfo-alpha-L-threo-hex-4-enopyranosyluronic acid)-4,6-di-O-sulfo-D-galactose) isomers of chondroitin using capillary zone electrophoresis. In addition, it is possible to separate oligomers of hyaluronan by similar protocols. These techniques represent a rapid, sensitive, and reproducible technique for the assay of these molecules from digests of connective tissues.

Boric Acids↗
PubMed1991

Identification of contemporary plasmid virulence genes in ancestral isolates of Salmonella enteritidis and Salmonella typhimurium.

Six epidemiologically distinct ancestral strains of Salmonella enteritidis and 5 of S. typhimurium from the pre-antibiotic era were examined for plasmid content, and for presence of plasmid genes implicated in mouse-virulence. Five sizes of plasmid were detected in S. enteritidis varying from 1 to 60 MDa. Two sizes of plasmid were found in S. typhimurium, 28 and 60 MDa. Plasmids of the same size were not common to both serovars. The HindIII restriction patterns of 3 of the ancestral S. enteritidis plasmids were identical to the modern 38 MDa plasmid, while all contained identical bands of 3.5, 2.7 and 1.9 kb. All the 60-MDa S. typhimurium plasmids, ancestral and contemporary, had an identical restriction pattern. Three different sized S. enteritidis plasmids and one size S. typhimurium plasmid contained a 3.5-kb DNA fragment carrying the virulence locus VirA. The VirB virulence locus was located on a 2.7-kb DNA fragment in S. enteritidis and on a 2.5-kb fragment in S. typhimurium. Both loci were precisely conserved between the ancestral strains and the modern representatives of both serovars.

DNA Fingerprinting↗
PubMed1988

Organ selective conversion of prostaglandin D2 to 9 alpha, 11 beta-prostaglandin F2 and its subsequent metabolism in rat, rabbit and guinea pig.

Cell-free 100,000 g supernatants from liver, kidney, lung and caecum of rat, rabbit and guinea-pig were compared for their ability to transform prostaglandins F2 alpha, D2, E2 and 9 alpha, 11 beta-prostaglandin F2 (11epi-PGF 2 alpha) to metabolic products. Experiments utilized multitritiated substrate PGs, with assessment of biotransformation by TLC, HPLC and GC/MS. PGF2 alpha was converted via the sulphasalazine analogue-inhibitable NAD+-dependent 15-hydroxy-prostaglandin dehydrogenase pathway (15-PGDH), with high activity (greater than 5 pmol/min/mg protein) in all 12 systems except rat and rabbit liver (e.g. guinea-pig kidney and rat caecum both 64 pmol/min/mg; rat liver 0.3 pmol/min/mg), forming 15-keto and 13,14-dihydro-15-keto metabolites as determined by TLC, HPLC and GC/MS. Prostaglandin D2 was not transformed in similar fashion in NAD+- or NADP+-supplemented incubations in any of the 12 cytosolic systems. However, PGD2 was converted to a single product identified by TLC, HPLC and GC/MS as 9 alpha, 11 beta-PGF2 in certain of the systems when supplemented with an NADPH regenerating system, with high activity in guinea-pig kidney (55.0 pmol/min/mg), guinea-pig liver (27.5 pmol/min/mg) and rabbit liver (13.7 pmol/min/mg) and less than 5 pmol/min/mg in 8 of the remaining 9 systems. This stereospecific 11-ketoreductase of rabbit and guinea-pig liver was stable to 10 min heating at 50 degrees, dialysis, storage at -20 degrees and repeated freeze/thawing but was not inhibited by sulphasalazine analogues. The 11-ketoreductase had a markedly different tissue profile from PGE2 9-ketoreductase, which was shown to convert PGE2 stereospecifically to 9 alpha, 11 alpha-prostaglandin F2 (PGF2 alpha) and was present at highest activity in rabbit liver and kidney. Evidence was obtained that 9 alpha, 11 beta-PGF2 was actively transformed by the sulphasalazine-inhitable 15-PGDH pathway at approximately one third of the rate of PGF2 alpha with high activity in several cytosolic systems (e.g. rat caecum, guinea-pig liver and kidney), suggesting that further transformation in vivo of this biologically active product of PGD2 metabolism could be initiated by this route.

Animals↗
PubMed1988

The presence of two complete homologous meta pathway operons on TOL plasmid pWW53.

pWW53 is a 110 kbp catabolic plasmid which encodes the complete pathway for the utilization of toluene and the xylenes. The upper pathway operon xylCAB is located between two homologous but distinct meta pathway operons, xylDLEGF(I,J,K)H, which are in direct repeat. These have each been cloned on large HindIII restriction fragments HA (17.5 kbp) and HB (15.6 kbp), the restriction sites of which have been mapped. During growth of MT53 on benzoate, mutants which have lost the ability to grow on hydrocarbons such as m-xylene (Mxy-) but which retain the ability to grow on their carboxylic acid metabolites such as m-toluate (Mtol+) take over the culture before ultimately being displaced by plasmid-free strains which are Mxy- Mtol-. The plasmids in the Mxy- Mtol+ mutants are formed by a large deletion between homologous regions of the two duplicate meta pathway operons. This causes the loss of the intervening xylCAB operon and the formation of a hybrid xylDLEGF(I, J, K)H operon, starting with the genes originally on HA and terminating with the genes originally on HB.

Cloning, Molecular↗
PubMed1979

PGE1 metabolism by the perfused rat liver.

The hepatic and biliary metabolites of PGE1 have been isolated and identified after infusions of PGE1 into isolated rat liver preparations. The results demonstrate that in general PGE1 undergoes metabolism similar to that of PGE2 in the rat and reveals the possibility of a selective PG metabolite transport system across the biliary canalicular membrane.

Animals↗
PubMed1978

Modification of prostaglandin and thromboxane release by immunological sensitisation and successive immunological challenges from guinea-pig lumg.

The release of prostaglandins (PGs) and thromboxanes (Txs) from perfused guinea pig lungs was investigated during different immunological states. The major product released from normal lungs perfused with exogenous arachidonic acid was 6-oxo-PGF1a. The procedure of sensitisation to specific antigen resulted in an increase in the release of 15-oxo-13,14-dihydro-TxB2 and a decrease in the release of 6-oxo-PGF1a- and 6,15-dioxo-13,14-dihydro-PGF1a from lungs perfused with arachidonic acid. The relative amount of 15-oxo-13,14-dihydro-TxB2 released progressively increased with the number of immunological challenges with both exogenous and endogenously derived substrate, arachidonic acid. This change in response to successive immunological challenges may represent a protective mechanism to prevent parent Txs and PGs entering the systemic circulation.

Anaphylaxis↗
PubMed1977

Decline in ribonucleic acid and protein synthesis with loss of viability during the early hours of imbibition of rye (Secale cereale L.) embryos.

A decline in protein synthesis and slow germination accompanies loss of viability in embryos of rye (Secale cereale L.) grains. Associated with this, incorporation of precursors into all the major classes of RNA is decreased and the processing of precursor rRNA to 25S and 18S RNA is retarded. Embryos that just reach 0% viability still synthesize some low-molecular-weight non-nucleolar material, although they do not synthesize protein. It is suggested that early-synthesized RNA could play a major part in determining the extent of protein synthesis at early germination, and thereby regulate the rate at which germination can proceed.

Plant Proteins↗
PubMed1977

Analysis of nucleosomal deoxyribonucleic acid in a higher plant.

Comparisons of nuclease digestions of chromatin in nuclei from rye embryos and rat liver show that their nucleosomal DNA is similar, i.e. DNA subunits consist of 200 base-pair repeats with 140 base-pair cores of identical substructure. The identical nucleosome structure is present in nuclei from cells of rye embryos that have been non-viable (i.e. dead) for more than 7 years. These findings indicate a high degree of stability of the DNA-histone complex and are consistent with conservation of the nucleosomal structure of chromatin during evolution.

Base Sequence↗
PubMed1977

Mass spectral characterization of 6-oxo-OGF.

The mass spectra of eleven derivatives are presented to provide structural support for the recently discovered prostaglandin, 6-oxo-PGF1alpha, which we have isolated from incubations of arachidonic acid with ram seminal vesicles or released during isolated perfusions of sensitized guinea pig lungs.

Animals↗
PubMed1977

The identification of two novel prostaglandins and a thromboxane.

6,15-Dioxo-PGF1alpha, 6,15-dioxo-13,14-dihydro-PGF1alpha and 15-oxo-thromboxane B2 have been identified in incubates of ram seminal vesicle homogenates with added arachidonic acid or in the perfusate from sensitised challenged guinea pig lungs. These compounds are probably related to 6-oxo-PGF1alpha and thromboxane B2. The structures have been determined by gas chromatography mass spectrometry, following suitable chemical derivatisation.

Animals↗
PubMed1977

The pharmacology of prostaglandin-like substances released from guinea-pig lungs during anaphylaxis.

The pharmacology of the prostaglandins (PGs) and thromboxanes (Txs) released from immunologically challenged guinea-pig lungs is related to their roles in the anaphylactic response. 6-oxo-PGF1alpha probably contibutes substantially to bronchoconstriction during anaphylaxis. TxB2 may contribute to the anaphylactic response by increasing SRA-A release and by stimulating leucotaxis. The 15-oxo metabolites of PGE2 and PGF2alpha are rather weak spasmogens, but might modify respiratory muscle contractions and pulmonary vascular resistance. The 15-oxo 13,14 dihydro metabolites of PGE2 PGF2alpha and TxB2 were inactive in the systems studied, suggesting an important inactivating role for the 13:14 reductase enzyme.

Anaphylaxis↗