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Biomedical subjects

M R Pollard

Publications and source records attributed to M R Pollard.

12 recordsLinked to original sources
PubMed1991

A specific acyl-ACP thioesterase implicated in medium-chain fatty acid production in immature cotyledons of Umbellularia californica.

Umbellularia californica (California Bay) seeds accumulate 10:0 and 12:0 as principal reserve fatty acyl groups. An in vitro fatty acid synthesis system from the developing cotyledons produces chiefly 10:0 and 12:0, in approximately the same proportions as the intact tissue. The kinetics of acyl thioester and free fatty acid formation in this system suggest that a medium-chain specific acyl-acyl-carrier protein (ACP) hydrolysis mechanism is responsible for the preponderance of medium-chain products. A crude extract of the developing cotyledons exhibits hydrolytic activity toward acyl-ACPs, with marked preference for 12:0-ACP and 18:1-ACP in the test series 6:0, 8:0, 10:0, 11:0, 12:0, 14:0, 16:0, and 18:1-ACPs. Partial purification of the 12:0-ACP hydrolytic activity has resulted in its separation from the 18:1-ACP hydrolase(s) and the 12:0-coenzyme A hydrolase(s) that are also present, thereby demonstrating its specificity for the 12-carbon acyl chain length and the ACP derivative. During cotyledon development, as the proportion of medium-chain to other fatty acyl groups increases, the extractable yield of this activity also increases substantially. Collectively these results suggest a role for this 12-ACP thioesterase in medium-chain production in vivo.

Coenzymes↗
PubMed1978

Disease prevention and health promotion initiatives: some legal considerations.

Public health programs to prevent disease and promote health are constrained by legal doctrines that protect individuals from intrusive regulation of their health-influencing behaviors. This paper outlines the parameters of acceptable interventions in the context of antismoking legislation and motorcycle helmet safety laws. The authors discuss recent court decisions challenging the constitutionality of these laws and identify criteria the courts apply in reviewing governmental attempts to protect the public from disease or trauma.

Coercion↗
PubMed1977

Studies on the inhibition of the desaturases by cyclopropenoid fatty acids.

Unwashed rat liver microsomes were used to study the inhibition of the delta6 and delta9 desaturases by cyclopropenoid fatty acids with the ring structure about the 9,10 or 6,7 carbon atoms. The 9,10 cyclopropenoid acid (sterculic acid) is shown to be an effective inhibitor of only delta9 desaturase and then only in the presence of MgCl2 and coenzyme A (presumably due to the formation of sterculoyl-CoA). Two 6,7 cyclopropenoid acids of different chain lengths showed no marked inhibition of either the delta6 or delta9 desaturase. By the use of [3H]-sterculic acid, it has been shown that under conditions of high inhibition of the delta9 desaturase the inhibitor is not covalently attached to the enzyme at any point. This disproves older ideas on the mechanism of inhibition that assumed reaction between the cyclopropenoid ring and sulphydryl groups on the enzymes.

Animals↗
PubMed1976

Fatty acids. Part 48. 13C nuclear magnetic resonance studies of acetylenic fatty acids.

The 13C NMR spectra of thirty-seven alkynoic acids (C8-C18) and ten alkadiynoic acids (C18 and C20) are reported and interpreted. The influence of COOH, COOCH3, CH3, and C identical to C groups on the chemical shifts of nearby carbon atoms is assessed. These influences are largely additive so that available spectra are readily interpreted and the spectra of new compounds of this type can be predicted. These preliminary results indicate that 13C NMR spectroscopy should be of considerable value in the structural identification of acetylenic compounds.

Acetylene↗