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R O Adlof

Publications and source records attributed to R O Adlof.

29 records · Page 2Linked to original sources
PubMed1989

Incorporation of deuterium-labeled fatty acids into human milk, plasma, and lipoprotein phospholipids and cholesteryl esters.

Fatty acid metabolism and the contribution of dietary fatty acids to milk cholesteryl ester (CE) and phospholipid (PL) were investigated in normal lactating mothers. The approach used was to feed mixtures of triglycerides containing deuterium-labeled palmitic acid (16:0-2H2), oleic acid (18:1-2H6), and linoleic acid (18:2-2H4). Milk and plasma samples were collected for 72 hr. Triglyceride (TG), CE, and PL fractions from milk, plasma, and lipoprotein were isolated and analyzed by gas-liquid chromatography and mass spectrometry. Data for the milk CE and PL fractions showed a definite selectivity for incorporation of 16:0-2H2 and 18:1-2H6 relative to 18:2-2H4. Based on the ratios of the deuterated fatty acids incorporated into the milk CE and PL samples, their incorporation times and isotopic enrichment data, it appears that these fatty acids are supplied mainly by the TG derived from chylomicrons and very low density lipoproteins. Plasma and lipoprotein CE data showed a progressive increase in 18:2-2H4 content, with 16:0-2H2 and 18:1-2H4 remaining relatively constant over the collection period. Plasma and lipoprotein PL data showed a higher rate for incorporation of 18:2-2H4 than 16:0-2H2 and 18:1-2H6 over the course of the sampling period. Comparison to previous data from adult males indicates lactation does not have a major effect on the general metabolism of these fatty acids. An increase with time in the isotopic enrichment of 18:2-2H4 in the plasma and lipoprotein CE and PL samples was observed which is consistent with in vitro selectivities reported for lecithin:cholesterol acyltransferase and phosphatidylcholine acyltransferase.(ABSTRACT TRUNCATED AT 250 WORDS)

Cholesterol Esters↗
PubMed1987

Metabolism in humans of cis-12,trans-15-octadecadienoic acid relative to palmitic, stearic, oleic and linoleic acids.

Mixtures of triglycerides containing deuterium-labeled hexadecanoic acid (16:0), octadecanoic acid (18:0), cis-9-octadecenoic acid (9c-18:1), cis-9,cis-12-octadecadienoic acid (9c, 12c-18:2) and cis-12,trans-15-octadecadienoic acid (12c,15t-18:2) were fed to two young-adult males. Plasma lipid classes were isolated from samples collected periodically over 48 hr. Incorporation and turnover of the deuterium-labeled fats in plasma lipids were followed by gas chromatography-mass spectrometry (GC-MS) analysis of the methyl ester derivatives. Absorption of the deuterated fats was followed by GC-MS analysis of chylomicron triglycerides isolated by ultracentrifugation. Results were the following: (i) endogenous fat contributed about 40% of the total fat incorporated into chylomicron triglycerides; (ii) elongation, desaturation and chain-shortened products from the deuterated fats were not detected; (iii) the polyunsaturated isomer 12c,15t-18:2 was metabolically more similar to saturated and 9c-18:1 fatty acids than to 9c,12c-18:2; (iv) relative incorporation of 9c,12c-18:2 into phospholipids did not increase proportionally with an increase of 9c,12c-18:2 in the mixture of deuterated fats fed; (v) absorption of 16:0, 18:0, 9c-18:1, 9c,12c-18:2 and 12c,15t-18:2 were similar; and (vi) data for the 1- and 2-acyl positions of phosphatidylcholine and for cholesteryl ester fractions reflected the known high specificity of phosphatidylcholine acyltransferase and lecithin:cholesteryl acyltransferase for 9c,12c-18:2. These results illustrate that incorporation of dietary fatty acids into human plasma lipid classes is selectively controlled and that incorporation of dietary 9c,12c-18:2 is limited. These results suggest that nutritional benefits of diets high in 9c,12c-18:2 may be of little value to normal subjects and that the 12c,15t-18:2 isomer in hydrogenated fat is not a nutritional liability at the present dietary level.

Adult↗
PubMed1987

Human lactation: maternal transfer of dietary triglycerides labeled with stable isotopes.

A stable isotope tracer method was utilized to measure quantitatively the secretion of diet-derived fatty acids (FA) into human milk. A mixture of [2H6]tripalmitin, [2H18]-triolein, and [2H12]trilinolein was administered to three healthy, lactating women 22 to 30 years of age. Milk and blood samples were collected sequentially for 72 hr. The FA composition and concentration of total plasma, lipoprotein, and milk triglycerides were determined by gas-liquid chromatography (GLC) and the isotopic enrichment was determined by gas-liquid chromatography-mass spectrometry (GLC-MS). There were no statistically significant differences in mammary secretion of the individual fats, either by a single individual or between subjects. The mean secretion of fat by one breast was 5.11 +/- 1.26% of the dose (CV = 25%). There was a significant 6.0-hr delay between peak occurrence of the tracer in plasma and its occurrence in milk. The lipids are transported to the mammary gland primarily by the chylomicron and very low density lipoprotein triglycerides.

Adult↗
PubMed1986

Distribution of hexadecenoic, octadecenoic and octadecadienoic acid isomers in human tissue lipids.

The trans 16:1, 18:1 and 18:2 fatty acid composition of various human organ lipids was studied to determine if isomers accumulated in specific tissues. "Trans" isomers are defined as those fatty acids containing one or more trans double bonds. Adipose, kidney, brain, heart and liver tissue lipids were analyzed. Gas chromatography with a 100-SP2560 capillary column was used to characterize the various positional and/or geometrical isomers. The distribution of trans 16:1 and 18:1 isomers ranged from 0.3% in the brain to 4.0% in adipose tissue, while trans 18:2 isomers ranged from 0.0% in the brain to 0.4% in adipose tissue. No trans 18:3 isomers were detected. Positional isomer ratios for cis 16:1 (delta 9 vs delta 7) and cis 18:1 (delta 11 vs delta 9) were also determined. Since these ratios are reproducible from one individual to the next, they might be useful for diagnosis of human metabolic disorders.

Adipose Tissue↗
PubMed1986

Absorption and distribution of deuterium-labeled trans- and cis-11-octadecenoic acid in human plasma and lipoprotein lipids.

Triglycerides of deuterium-labeled trans-11-, trans-11-cis-11- and cis-9-octadecenoic acid (11t-18:1-2H, 11c-18:1-2H) were simultaneously fed to two young adult male subjects. Plasma lipids from blood samples collected periodically for 48 hr were analyzed by gas chromatography-mass spectroscopy. The results indicate the delta 11-18:1-2H acids and 9c-18:1-2H were equally well absorbed; relative turnover rates were higher for the delta 11-18-1-2H acids in plasma triglycerides; incorporation of the delta 11-18:1-2H acids into plasma phosphatidylcholine was similar to 9c-18:1-2H, but distribution at the 1- and 2-acyl positions was substantially different; esterification of cholesterol with 11t-18:1 was extremely low; chain shortening of the delta 11-18:1-2H acids was 2-3 times greater than for 9c-18:1-2H; no evidence for desaturation or elongation of the 18:1-2H acids was detected; and a 40% isotopic dilution of the 18:1-2H acids in the chylomicron triglyceride fraction indicated the presence of a substantial intestinal triglyceride pool. Based on our present knowledge, these metabolic results for delta 11-18:1 acids present in hydrogenated oils and animal fats indicate that the delta 11 isomers are no more likely than 9c-18:1 to contribute to dietary fat-related health problems.

Cholesterol Esters↗
PubMed1985

In vivo distribution and turnover of trans- and cis-10-octadecenoic acid isomers in human plasma lipids.

Triacylglycerols containing deuterium-labeled trans-10- and cis-10-octadecenoic acid (10t-18:1, 10c-18:1) plus the triacylglycerol of deuterated cis-9-octadecenoic acid (9c-18:1) were fed as a mixture to two young, adult male subjects. Analysis by mass spectroscopy of the labeled fats in blood samples collected periodically for 48 h allowed the uptake, distribution and turnover of both 10-octadecenoic acid isomers to be directly compared to 9c-18:1. A feature of this study is that actual weight data for the labeled fats were obtained. These data allowed plasma triacylglycerol turnover rates of 3.47-5.13 mg/min per kg to be estimated. Plasma and chylomicron triacylglycerol data also provided evidence that absorption of the deuterated fats mobilized 10-12 g of a triacylglycerol pool present in the intestinal cells. Other results are summarized as follows: the 10t-, 10c- and 9c-18:1 fatty acids were equally well absorbed, both delta 10-18:1 isomers were oxidized more rapidly than 9c-18:1, conversion of the delta 10-18:1 isomers into their corresponding 16:1 isomers was about 3-times faster than for 9c-18:1, the delta 10-18:1 isomers were preferentially incorporated at the 1-acyl and excluded from the 2-acyl position of phosphatidylcholine, esterification of cholesterol with the delta 10-18:1 fatty acids was 2.5-4.3-times slower than for 9c-18:1 and desaturation and elongation rates for the delta 10-18:1 acids were very low.

Adult↗
PubMed1983

Incorporation of deuterium-labeled trans- and cis-13-octadecenoic acids in human plasma lipids.

The absorption and distribution of deuterated trans- and cis-13-octadecenoic acid (13t-18:1 and 13c-18:1) in plasma lipids were compared to deuterated cis-9-octadecenoic acid (9c-18:1) in two young adult male subjects. A mixture of triglycerides was fed in a multiple-labeled experiment where each triglyceride contained a fatty acid labeled with a different number of deuterium atoms. Analysis of human plasma lipids by mass spectroscopy allowed the distribution of the two 13-octadecenoic acid isomers to be directly compared to cis-9-octadecenoic acid. Plasma lipids selectively excluded both the 13t-18:1 and 13c-18:1 isomers relative to 9c-18:1 in all neutral and phospholipid fractions. Discrimination against incorporation of the 13t-18:1 isomer into plasma cholesteryl ester and 2-acyl phosphatidylcholine was nearly absolute. The 1-acyl phosphatidylcholine fraction exhibited a large positive selectivity for the 13t-18:1 isomer. Differences in the relative distribution of the trans and cis 13-18:1 isomers vs. 9c-18:1 in the various lipoprotein lipid classes were found. Analysis of the chylomicron triglyceride component of the plasma lipids indicated all three fatty acids were equally well absorbed.

Adult↗
PubMed1980

Distribution of deuterium-labeled cis- and trans-12-octadecenoic acids in human plasma and lipoprotein lipids.

Triglycerides containing cis- and trans-12-octadecenoic acid (12c-18:1 and 12t-18:1) and cis-9-octadecenoic acid (9c-18:1) labeled with deuterium were fed to 2 young adult male subjects. These fatty isomers each contained a different number of deuterium lables, which allowed mass spectrometric analysis to distinguish among them after they were fed as a mixture. This approach results in a direct comparison of the absorption and distribution of these 3 monenoic acids into blood plasma and lipoprotein lipids. Plasma lipid data indicated that all phospholipid fractions selectively incorporate 12c-18:1 and 12t-18:1 in preference to 9c-18:1. Discrimination against 12c-18:1 and 12t-18:1 compared to 9c-18:1 was found in the plasma neutral lipids, with a strong discrimination against 12t-18:1 incorporation into the cholesteryl ester fraction. Considerable reduction in the percentage of linoleic and arachidonic acid was observed when 12-18:1 isomers were incorporated in plasma triglyceride, phosphatidylcholine and spingomyelin samples. Chylomicron lipid analyses indicated that all isomers were well absorbed. Variation was observed in the relative distribution of 12c-18:1, 12t-18:1 and 9c-18:1 between the very low density, low density and high density lipoprotein lipid classes. No desaturation of 12c-18:1 to linoleic acid was detected.

Adult↗
PubMed1979

Incorporation of deuterium-labeled cis- and trans-9-octadecenoic acids in humans: plasma, erythrocyte, and platelet phospholipids.

The objective of this study was to follow the uptake and distribution of oleic and elaidic acids into human erythrocytes, platelets, and plasma phospholipids. The use of dual and triple labeling methodology permitted a precise comparison of elaidic and oleic acid utilization. Elaidic acid (EI) was selectively concentrated in all the plasma phospholipids except for lysophosphatidylcholine. Three times more elaidic than oleic acid (OI) accumulated in the 1-acyl position of phosphatidylcholine, as determined by hydrolysis with phospholipase A2. Rapid incorporation and removal of elaidate were observed for all samples. These results support the concept that enzymes responsible for acylation of phospholipids are sensitive to double bond configuration and the physical properties of the fatty acid moieties. Labeled fatty acid levels in red cell and platelet phospholipids were much lower than for plasma phospholipids, indicating a relatively slow rate for the in vivo incorporation of fatty acids into blood cell membrane phospholipids. No isotope effect was found when oleic acid labeled with deuterium on the double bond was used.

Adult↗