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Biomedical subjects

R Hutton

Publications and source records attributed to R Hutton.

5 recordsLinked to original sources
PubMed1991

Qualitative assessment of von Willebrand factor (vWF) in cirrhotics following repeated doses of desmopressin acetate.

Qualitative abnormalities in von Willebrand Factor (vWF) in patients with cirrhosis have been little studied with contrasting results. We used crossed immunoelectrophoresis (2-DIE) and multimeric analysis of vWF in eight patients with stable hepatic cirrhosis to evaluate abnormalities in vWF before and 1 h following intravenous administration of three doses of desmopressin acetate (0.3 micrograms/kg) given at baseline, 4 and 24 h. We thought that qualitative abnormalities might be more easily detected following desmopressin as this is known to release vWF from storage sites. There was an increased electrophoretic mobility on 2-DIE in all patients with no change following desmopressin. The multimeric analysis did not show an increase in lower molecular weight multimers, but showed a statistically significant increase in higher molecular weight multimers following desmopressin (P less than 0.02). These results suggest that the vWF of cirrhotics has an abnormal charge (not altered by release following desmopressin) which would explain the increased electrophoretic mobility on 2-DIE with a normal pattern of lower molecular weight multimers using multimeric analysis.

Deamino Arginine Vasopressin↗
PubMed1986

A two-site, monoclonal antibody-based immunoassay for von Willebrand factor--demonstration that vWF function resides in a conformational epitope.

Two monoclonal antibodies (RFF-VIII:R/1 and RFF-VII:R/2) which recognise the same epitope on von Willebrand factor (vWF) have been used in a simple, two-site, solid-phase immunoradiometric (IRMA) or enzyme-linked assay (ELISA) to analyse vWF in plasma from normal individuals and from patients with von Willebrand's disease (vWD). Results obtained confirm our previous findings (using RFF-VIII:R/2 in a one-site, fluid-phase IRMA) that the MAbs detect the presence of an epitope on the vWF molecule that reflects its function. This epitope is involved in vWF binding to the GPIb protein on platelets. It is reduced in all types of vWD, including type II (or variant) vWD. It is present in normal plasma, in vWF released from normal platelets and from cultured umbilical cord vein endothelial cells. The epitope is, however, found to be reduced in serum. Studies on SDS-treated vWF prove that this GPIb-binding site is dependent on the conformation of the vWF multimers.

Antibodies, Monoclonal↗
PubMed1985

An immunoradiometric assay for human factor VIII/von Willebrand factor (VIII:vWF) using a monoclonal antibody that defines a functional epitope.

A murine monoclonal antibody has been produced (RFF-VIII:R/2) that binds specifically to human factor VIII-related antigen (VIII:RAg) in plasma and in vascular endothelial cells but has no reactivity with factor VIII procoagulant antigen (VIII:cAg). This antibody is a potent inhibitor of von Willebrand factor activity (VIII:vWF) in that it can totally neutralize ristocetin-induced aggregation of platelet rich plasma and inhibit platelet adhesion at high flow rates. RFF-VIII:R/2 can be used in a one-stage, fluid phase immunoradiometric assay that can detect VIII:RAg at concentrations of 0.001 u/ml. This method has been used to analyse plasma from patients with von Willebrand's disease (vWD). Results obtained in these patients showed a high degree of correlation between the monoclonally-defined epitope and VIII:vWF levels measured by ristocetin-induced aggregation of washed platelets. This correlation was maintained in those patients with the 'variant' types of vWD who exhibit highly disparate VIII:vWF and VIII:RAg levels when the latter is determined using polyclonal antisera. It appears that this monoclonal antibody recognizes a site on the VIII:RAg molecule which is associated with its interaction with the platelet membrane. Immunoradiometric assays using RFF-VIII:R/2 offer a simplified, reproducible means of detecting functionally-active VIII:RAg as an alternative or supplement to techniques involving platelet interactions.

Animals↗
PubMed1979

Effects of deferoxamine methanesulfonate on Trichophyton mentagrophytes.

Deferoxamine methanesulfonate (Desferal), an iron chelator, inhibited germ tube formation and growth of Trichophyton mentagrophytes in a microculture assay. A 50% reduction of germ tube formation required Desferal at 5 mg/ml and a 50% reduction of growth required 1.5 mg/ml. Growth was almost completely inhibited with 50 and 100 mg/ml. Also, Desferal at 100 mg/ml inhibited further elongation when added to short hyphae (II and 21 micrometer), but showed less inhibitory effects when added to long hyphae (64 micrometer). Iron (133 microgram/ml) reversed the inhibition of growth produced by incubating spores with Desferal at 5 mg/ml, providing iron was added before 72 h incubation. Desferal at 100 mg/ml decreased viability of activated spores incubated for 3 days at 30 degrees C, but did not decrease viability of spores incubated for 3 days at 4 degrees C. The growth inhibitory effect of Desferal and transferrin were compared. Transferrin was inhibitory at low molarities (0.001 to 1.0 mM), while Desferal was inhibitory only at higher molarities (greater than 1 mM). Desferal (0.05 mM) also reversed the inhibition expected with 0.05 mM transferrin. These findings indicate that Desferal and transferrin deprive T. mentagrophytes of nutritional iron and thus inhibit growth of the fungus. Low concentrations of Desferal can also promote growth in the presence of transferrin.

Deferoxamine↗