PubMed Health⌕ Search

Biomedical subjects

G Mulryan

Publications and source records attributed to G Mulryan.

5 recordsLinked to original sources
PubMed1993

Bovine serum amine oxidase: some differences between chromatographically defined forms including sensitivity to inhibition by dithiomolybdate.

1. Bovine serum amine oxidase (BSAO) forms, defined by DEAE-cellulose and hydroxyapatite chromatography, were shown to have different kinetic characteristics with p-dimethylaminobenzylamine as a substrate; there was also some variation in heat sensitivity. 2. The forms showed similar sensitivity to inhibition by aminoguanidine but there were differences with respect to dithiomolybdate. 3. The results also provided some support for the view that both subunits were active catalytically. 4. It is concluded that while the forms were interconvertible, the practice of pooling different chromatographic fractions may not be acceptable in all circumstances. 5. While inhibition by dithiomolybdate is of biochemical interest it is concluded that inhibition of BSAO by thiomolybdates is unlikely to play a role in the clinical syndromes which are common in cattle exposed to Mo in the herbage.

Amine Oxidase (Copper-Containing)↗
PubMed1992

Assessment of liver copper status in cattle from plasma copper and plasma copper enzymes.

Copper status determined by liver biopsy was also assessed by 3 plasma parameters: total plasma copper (Cu) as well as ceruloplasmin (Cp) and amine oxidase E.C.1.4.3.6. (AO) activities. While 14 out of the 98 cattle, all kept in field conditions, had liver copper levels of less than 20 mg/kg only 5 of these could be distinguished by low plasma Cu and 3 by low Cp activity. In addition, some animals with apparently adequate liver copper had relatively low plasma Cu values, ca 0.5-0.6 mg/l. None of the cattle had decreased AO activity. When all 3 plasma parameters were combined in the form [AO] divided by ([Cp] x [Cu]), detection of the low liver copper was improved in that 9 out of 14 could be distinguished, whereas animals with more than 20 mg/kg DM liver Cu could not. It is suggested that this relationship, tentatively called an index, would merit examination in other situations, since it might provide a better guide to copper status and indicate whether copper repletion therapy was worthwhile.

Amine Oxidase (Copper-Containing)↗
PubMed1989

Behavior of [185W]thiotungstates injected into sheep and the influence of copper: their fate and the effect of the compounds upon plasma copper.

[185W]trithio- and tetrathiotungstates (0.5 mg W) were injected intravenously into sheep. The compounds circulated in plasma bound reversibly to plasma proteins, particularly to albumin. After the first few minutes, levels declined exponentially with a T 1/2 of 12-14 hr. The initial movement of [185W]trithiotungstate from the plasma compartment was delayed transiently by the immediate injection of copper (2-6 mg); the longer-term metabolism was unaffected. The final fate of the compounds appeared to be hydrolysis and excretion in urine as [185W]tungstate. 185W from [185W]trithiotungstate appeared more rapidly than from [185W]tetrathiotungstate, but in both the rate was unaffected by copper injections. Since the appearance in urine did not correspond to the disappearance from plasma, it was suggested that the hydrolysis occurred in extravascular tissues and that the liver might be the site. A control experiment showed that [185W]tungstate in plasma was very rapidly cleared (and appeared in urine). At higher W levels (25-50 mg W per sheep per day), systematic copper metabolism was perturbed since plasma copper levels rose. The experiments demonstrated that in sheep the behavior and the effects of thiotungstates and thiomolybdates are sufficiently similar for 185W to be used as a more convenient alternative to 99Mo for longer-term studies on the interaction of the compounds with copper metabolism in animals.

Animals↗
PubMed1988

Studies of the changes in systemic copper metabolism and excretion produced by the intravenous administration of trithiomolybdate in sheep.

1. The effects of intravenous trithiomolybdate administration on the fate of 64Cu and on stable Cu metabolism were examined in sheep held in metabolism cages and fed on a low-Cu diet supplying 2.95 mg Cu/animal per d. 2. In Expt 1 the injection of trithiomolybdate, 30 mg molybdenum/sheep per d for 5 d, greatly increased plasma Cu levels and more than doubled the faecal Cu excretion. Urinary Cu excretion was unaffected. The disappearance from plasma of 64Cu injected during the trithiomolybdate administration was slowed although faecal 64Cu excretion was increased more than threefold. 3. In Expt 2 trithiomolybdate, 10 and 30 mg Mo/sheep per d for 3 d, was administered 22 h after the injection of 64Cu. Radioactivity reappeared immediately in plasma and faecal 64Cu excretion was increased. 4. In both experiments the 64Cu and the increased stable Cu in plasma were associated with albumin. 5. The experiments explain the effectiveness of thiomolybdates as 'decoppering' agents and provide a model for some of the systemic effects seen in ruminants exposed to increased dietary Mo. The experiments support the view that the thiomolybdates, by causing the appearance of new ligands, alter the distribution of Cu in tissues and cause an overall depletion.

Animals↗