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Biomedical subjects

D L Palmquist

Publications and source records attributed to D L Palmquist.

66 records · Page 4Linked to original sources
PubMed1976

Contribution of intermuscular fat to lipogenesis from dietary glucose carbon in mice.

We assessed the contribution of various tissues to the synthesis of fat from glucose carbon in mice during rapid lipogenic activation induced by a glucose test meal. Nibbling and gorging mice were maintained on a 58% glucose, fat-free diet. The mice were fasted 22 h and refed 5-10 muCi [U-14C]glucose (120 mg/20 g body weight) either by gastric intubation or as a test meal (58% glucose diet). The muscular carcass in both nibblers an gorgers contained more than 75% of the total radioactivity in the fatty acids derived from glucose; liver and epididymal fat pad accounted for only a small percentage. Mort than half the carcass activity was in the "muscular" tissue as neutral lipid acids. We could isolate a discrete fat body in the popliteal region of the leg muscle ("muscle fat", "intermuscular fat"). The popliteal fat converted glucose carbon to fatty acids an order of magnitude faster, per unit weight, than the epididymal fat pad or skeletal muscle. The fatty acid moiety of the triacylglycerols had the major portion of the label in the popliteal fat 2 and 6 h after ingestion of the glucose test meals. The diacylglycerol pool was active at 2 h and its activity faded at 6 h implicating its intermediary role in lipid metabolism similar to published findings in epididymal fat pad. These results indicate that fat cells associated with the muscular carcass may play a major role in the de novo synthesis of fat from dietary carbohydrate in mice.

Adipose Tissue↗
PubMed1976

A kinetic concepto of lipid transport in ruminants.

Summarization of the literature shows a strong correlation between dietary fatty acid intake and total lipid concentration in plasma in lactating cows whereas total milk fat secreted is related to neither of these. In the process of plasma triglyceride removal, chylomicra and very low density lipoproteins are converted to low density lipoproteins. Limited kinetic data indicate that the fractional removal rates for chulomicra and very low density lipoproteins are rapid in lactating cows whereas fractional removal of low density lipoproteins is slower, resulting in accumulation of the latter in plasma. Under such conditions, low density lipoprotein concentrations of plasma would not be expected to reflect quantitatively the transfer of plasma triglyceride fatty acids to milk fat. Quantitative analysis or triglyceride fatty acid turnover in density less than 1.006 lipoproteins should delineate the role of plasma lipid transport in milk fat synthesis. High fat diets protected from rumen biohydrogenation have proven to be a useful approach in studying ruminant fat metabolism and may be used more extensively to elucidate the role of cholesterol in plasma lipid transport and the metabolism of essential fatty acids in ruminants.

Acetyl-CoA Carboxylase↗
PubMed1976

Relative activation of milk lipoprotein lipase by serum of cows fed varying amounts of fat.

A routine laboratory assay to evaluate relative concentrations of lipoprotein lipase activator (apo C-II) in cow serum was developed. The assay was linear for at least 120 min after an initial, unexplained, lag ime of 13 to 15 min. Half-maximal activation was in the range of 1 to 2% serum in the assay. Inhibition of activation was indicated at high amounts (10%) of serum. Activation from plasma was half that from serum, presumably caused by an increase in substrate Km in the presence of heparin. Use of glyceryl tri[9,10-3H] oleate yielded excessively high blanks; [2-3H] glyceryl triolein is suggested for routine assay. Relative amounts of activator were not different between dry and lactating cows fed "conventional" diets. Activator concentration increased linearly with increasing dietary fat and was related to concentration of total lipid in plasma. The assay may provide a useful adjunct in studies on lipoprotein metabolism.

Animals↗
PubMed1976

Polyunsaturated meat and dairy products in fat-modified food patterns for hyperlipidemia.

Polyunsaturated meat and dairy products were compared with their saturated counterparts to determine their usefulness in a fat-modified diet for hyperlipidemic persons and their spouses. These polyunsaturated animal products were produced by feeding cattle a supplement of oil droplets coated with denatured protein. As a result, the polyunsaturated fatty acid content was 27 to 28 per cent of the meat fat and butterfat; saturated fatty acids (C12:0 to tc16:0) were 18 to 19 per cent. Of the eleven free-living subjects three were normocholesteremic, three had type IIa hyperlipidemia and five had type VI (IIb). In the fourteen-week study, an adjustment period of three weeks was followed by two consecutive experimental periods of four weeks each, then by a three-week follow-up period. During the adjustment period, participants continued to follow their usual eating patterns. During both experimental periods all followed the same prescribed fat modified food pattern using polyunsaturated margarine and oil. Five participants ate polyunsaturated beef and dairy products during the first experimental period and their saturated counterparts in the second; six participants ate saturated products first, then polyunsaturated. During the follow-up period, all participants selected all their own food. Serum cholesterol levels in five participants who had not previously followed a fat-modified diet were reduced by 18 per cent with polyunsaturated animal products and 11 per cent with saturated products. Serum cholesterol in six participants, previously on a fat-modified diet, was not significantly changed with polyunsaturated products. In ten of eleven participants, serum cholesterol levels were an average of 6 per cent lower with polyunsaturated products than with saturated products. It is concluded that polyunsaturated animal products are suitable for use in fat-modified food patterns for reducing hyperlipidemia, with some restrictions in the amount of polyunsaturated animal fat and with the inclusion of polyunsaturated oil and margarine.

Adult↗
PubMed1976

Equally rapid activation of lipogenesis in nibbling and gorging mice.

Minimal average rates of exogenous glucose-C-conversion to whole body, total lipid fatty acids were measured in nibbling and gorging mice. Gorgers trained to eat 1 meal/day (8-10 am) were fasted 22-24 hr and given [14C]glucose with pure glucose, 30% glucose in water, or a 58% glucose, fat-free diet. Conversion of glucose-C to total lipid fatty acids increased from 0.6 (fasted) to approximately 20 mug/min/20 g body weight during 40 min after glucose feeding using each test meal. Dietary amino acids were not required for activation of lipogenesis in gorgers. Exogenous glucose-C was incorporated into fatty acids as fast in nibbling mice as in gorgers. This was true after varying all of the following conditions: training period, number of meals gorged, previous fasting time, and diet composition. The total rate of fatty acid synthesis from body glucose-C during absorption of a glucose load was also estimated in absorption of a glucose load was also estimated in previously fasted nibbling and gorging mice. These estimates were based on composite, serial measurement of both plasma glucose specific activities and 14C-labeled fatty acids. The total rate of fatty acid synthesis from both exogenous and endogenous glucose-C was only 15% higher than the rate from exogenous glucose-C between 10 and 40 min. No significant differences between nibblers and gorgers were found.

Animals↗
PubMed1966

Enzymatic techniques for the study of pathways of carbohydrate utilization in the rumen.

Enzymatic techniques were used to study the metabolism of carbohydrates by ruminal bacteria. A direct relationship was observed between the proportions of acetate and propionate formed and the specific activities of the enzymes which participate in forming these acids. An inverse relationship between butyrate formation and butyrate-forming enzymes was observed. The relative activities of succinic dehydrogenase to fumaric reductase, nicotinamide adenine dinucleotide-linked glutamic dehydrogenase to nicotinamide adenine dinucleotide phosphate-linked glutamic dehydrogenase, and pyridine nucleotide-nonlinked lactic dehydrogenase to pyridine nucleotide-linked lactic dehydrogenase were affected by the level of concentrates in the diet. Lactyl coenzyme A dehydrase activity was below the limits of the assay technique in many samples from the alfalfa hay diet, and increased to relatively high levels when concentrates were fed. It is suggested that the enzymatic method will prove valuable for studying the contributions of individual microorganisms to the overall ruminal metabolism, and, with certain limitations, useful for estimating the relative contributions of alternate pathways.

Animal Feed↗