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W A Norton

Publications and source records attributed to W A Norton.

10 recordsLinked to original sources
PubMed1994

Plasma cis-dec-4-enoic acid measured by isotope dilution mass spectrometry; an improved assay to diagnose medium-chain acyl-CoA dehydrogenase deficiency.

An isotope dilution mass spectrometric assay for plasma cis-dec-4-enoic acid is described. It is quicker, more reliable and more accurate than previous methods. It confirmed previous findings that cis-dec-4-enoic acid is a reliable indicator for medium-chain acyl-CoA dehydrogenase deficiency (MCAD). The plasma cis-dec-4-enoic acid levels of both asymptomatic and symptomatic MCAD patients (3.5-71 mumol/L) are demonstrably higher than those of normal children (0.2-1.7 mumol/L), MCAD heterozygotes (0.1-1.5 mumol/L), those with other fatty acid oxidation defects (0.2-2.2 mumol/L) or those receiving high doses of valproic acid (0.2-0.4 mumol/L).

Acyl-CoA Dehydrogenase↗
PubMed1991

Direct measurement of soluble CD4 binding to human immunodeficiency virus type 1 virions: gp120 dissociation and its implications for virus-cell binding and fusion reactions and their neutralization by soluble CD4.

We have analyzed the binding of soluble CD4 (sCD4) to human immunodeficiency virus type 1 (HIV-1) virions (isolates IIIB and RF) at 4 and 37 degrees C by using a combination of gel exclusion chromatography and enzyme-linked immunosorbent assay detection systems. The sCD4 binding curve at 37 degrees C indicates that the affinity of the interaction of sCD4 with gp120 on the virion surface is indistinguishable from the affinity of sCD4 for the equivalent concentration of soluble gp120. At 4 degrees C, however, the affinity of sCD4 for virion-bound gp120 but not for soluble gp120 is reduced by about 20-fold. Binding of sCD4 (greater than 0.2 microgram/ml) to virions at 37 degrees C but not 4 degrees C induces the rapid dissociation of a major proportion of gp120 from gp41 on the virion surface. This dissociation requires occupancy by sCD4 of multiple (probably two) binding sites on a gp120-gp41 oligomer. At 37 degrees C there are two components to the neutralizing action of sCD4 on HIV-1; reversible, competitive inhibition at low sCD4 concentrations (less than 0.2 microgram/ml) and essentially irreversible inhibition due to gp120 loss at higher sCD4 concentrations. At 4 degrees C, sCD4 neutralizes HIV infectivity by competitive inhibition alone. These findings may have implications for the HIV-CD4+ cell binding and fusion reactions and the mechanism by which sCD4 blocks infectivity.

CD4 Antigens↗