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Biomedical subjects

M R Pollard

Publications and source records attributed to M R Pollard.

28 records · Page 2Linked to original sources
PubMed1980

The delta 5 and delta 6 desaturation of fatty acids of varying chain length by rat liver: a preliminary report.

The delta 6 desaturase of rat liver can accommodate substrates with a wide range of chain length. delta 9-cis, 12-cis-Dienoic acids of chain lengths 14-22 carbon atoms were all desaturated at the delta 6 position by microsmal preparations from rat liver. By contrast, the delta 5 desaturase appeared much more chain-length sensitive. The percentage delta 5 desaturation of a series of delta 8-cis- and delta 9-trans-monoenoic acids increased with increasing chain length (from C16 to C20).

Animals↗
PubMed1980

Long Chain (C(20) and C(22)) Fatty Acid Biosynthesis in Developing Seeds of Tropaeolum majus: AN IN VIVO STUDY.

The storage triacylglycerols of nasturtium (Tropaeolum majus) seeds are composed principally of cis-11-eicosenoate and cis-13-docosenoate. To investigate the biosynthesis of these C(20) and C(22) fatty acids, developing seed tissue was incubated with various (14)C-labeled precursors. Incubation with [1-(14)C]acetate produced primarily cis-11-[1-(14)C]eicosenoate and cis-13-[1,3-(14)C]docosenoate in the triacylglycerol fraction, the odd-carbon [U-(14)C]oleate also formed from [(14)C] acetate was in the polar lipid fraction. Kinetic data showed that this oleate was not channeled into cis-11-eicosenoate nor cis-13-docosenoate over a 24-hour period. Under suitable conditions, nasturtium seed could also produce [(14)C]stearate, [(14)C]eicosenoate, and [(14)C]docosenoate from [1-(14)C]acetate. The results are discussed in terms of the number of pathways producing fatty acids. From pool size and other considerations, the results can be rationalized only in terms of different de novo systems for oleate biosythesis, one supplying oleate for incorporation into phospholipids and the other supplying oleate for chain elongation and subsequent esterification into triacylglycerols. Because of the probable heterogeneous nature of the seed tissue, it is not known if these two systems are operating in different cell types, in the same cell type at different stages of development, or in the same cell type concurrently.

Journal Article↗
PubMed1980

Biosynthesis of C(20) and C(22) Fatty Acids by Developing Seeds of Limnanthes alba: CHAIN ELONGATION AND Delta5 DESATURATION.

The storage triacylglycerols of meadowfoam (Limnanthes alba) seeds are composed essentially of C(20) and C(22) fatty acids, which contain an unusual Delta5 double bond. When [1-(14)C]acetate was incubated with developing seed slices, (14)C-labeled fatty acids were synthesized with a distribution similar to the endogenous fatty acid profile. The major labeled product was cis-5-eicosenoate, with smaller amounts of palmitate, stearate, oleate, cis-5-octadecenoate, eicosanoate, cis-11-eicosenoate, docosanoate, cis-5-docosenoate, cis-13-docosenoate, and cis-5,cis-13-docosadienoate. The label from [(14)C]acetate and [(14)C]malonate was used preferentially for the elongation of endogenous oleate to produce cis-[(14)C]11-eicosenoate, cis-13-[(14)C]docosenoate, and cis-5,cis-13-[(14)C]docosadienoate and for the elongation of endogenous palmitate to produce the remaining C(20) and C(22) acyl species. The Delta5 desaturation of the preformed acyl chain and chain elongation of oleate and palmitate were demonstrated in vivo by incubation of the appropriate 1-(14)C-labeled free fatty acids. Using [1-(14)C]acyl-CoA thioesters as substrates, these enzyme activities were also demonstrated in vitro with a cell-free homogenate.

Journal Article↗
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↗