Showing papers on "Fatty acid published in 1970"

Splanchnic metabolism of free fatty acids and production of triglycerides of very low density lipoproteins in normotriglyceridemic and hypertriglyceridemic humans

Abstract: Transport of free fatty acids from the blood into the splanchnic region and their conversion to triglycerides of very low density lipoproteins, together with estimates of splanchnic oxidation of free fatty acids to ketones and to carbon dioxide and water, have been made in the postabsorptive state in seven normolipemic subjects, six with primary endogenous hyperlipemia and one each with primary dysbetalipoproteinemia and mixed hyperlipemia. Net systemic transport of free fatty acids into the blood was the same in normolipemic and hyperlipemic groups, but a greater fraction was taken up in the splanchnic region in the latter. Transport into the blood in very low density lipoproteins of triglyceride fatty acids derived from free fatty acids was proportional and bore the same relationship to splanchnic uptake of free fatty acids in the two groups. In normolipemic subjects, near equilibration of specific activities after 4 hr infusion of palmitate-1-(14)C showed that almost all triglyceride fatty acids of very low density lipoproteins and acetoacetate were derived from free fatty acids taken up in the splanchnic region. In the hyperlipemic subjects, equilibration of free fatty acidcarbon with acetoacetate was almost complete, but not with triglyceride fatty acids, owing at least in part to increased pool size. Comparison of the rate of equilibration of triglyceride fatty acids-(14)C with rate of inflow transport from the splanchnic region, together with other data, indicated that most of the circulating triglyceride fatty acids of very low density lipoproteins in hyperlipemic subjects were also derived from free fatty acids. Although mean inflow transport of triglyceride fatty acids was greater in the hyperlipemic subjects, it correlated poorly with their concentration and it appeared that efficiency of mechanisms for extrahepatic removal must be a major determinant of the concentration of triglycerides in blood plasma of the normolipemic as well as the hyperlipemic subjects. Estimates of splanchnic respiratory quotient supported the concept that oxidation of free fatty acids accounts for almost all of splanchnic oxygen consumption in the postabsorptive state. Splanchnic oxygen consumption was greater in the hyperlipemics, but fractional oxidation of free fatty acids to ketones was higher in normolipemic subjects. Calculations of splanchnic balance indicate that a larger fraction of free fatty acids was stored in lipids of splanchnic tissues in the hyperlipemics. No differences were found between the two groups in net splanchnic transport of glucose, lactate, or glycerol.

A possible role for singlet oxygen in the initiation of fatty acid autoxidation

Abstract: A mechanism for the initiation of autoxidation in fatty acids is proposed which involves singlet state oxygen, formed through a photosensitization reaction, as the reactive intermediate. Both singlet oxygen generated in a radio-frequency gasdischarge, and photosensitization by natural pigments, were shown to catalyze the oxidation of methyl linoleate. The involvement of singlet oxygen was shown by the identification of nonconjugated hydroperoxides as products common to both photooxidation and singlet O2 oxidation. Nonconjugated hydroperoxides could not be detected among the free radical autoxidation products. Further proof for the above mechanism was gained by showing that compounds known to react strongly with singlet oxygen, inhibited the photooxidation. With the exception of chlorophyll, all sensitizers could be completely inhibited. Although singlet oxygen formation can account for approximately 80% of the observed chlorophyll photooxidation, at least one other mechanism must be involved. It is postulated that proton abstraction by the photoactivated carbonyl group of chorophyll could account for the remaining 20% of the observed photooxidation. The conclusion is drawn that oxygen, excited to its singlet state by a photosensitization process, plays the important role of forming the original hydroperoxides whose presence is necessary before the normal free radical autoxidation process can begin.

Pancreozymin bioassay in man based on pancreatic enzyme secretion: potency of specific amino acids and other digestive products

Abstract: The ability of products of digestion to stimulate pancreozymin secretion in man was investigated using a bioassay procedure, based on duodenal perfusion, which quantified the total outputs of pancreatic enzymes evoked by intraduodenal stimuli under steady-state conditions. Patterns of response resulting from physiologic intraduodenal concentrations of test material were basal output (with isotonic saline), washout of enzymes (with dextrose, micellar fatty acid, and amino acids), and sustained output of enzymes (with amino acids and micellar fatty acid). The sustained secretion of pancreatic enzymes found during the 2nd hr of perfusion and subsequently was characteristic of pancreozymin-induced secretion. The enzyme output in response to a mixture of essential and nonessential amino acids was significantly higher than that evoked by micellar fatty acid and was comparable with that resulting from the maximally tolerated dose of pancreozymin given by vein. Perfusion with essential amino acids caused enzyme outputs comparable to those induced by perfusion with the original amino acid mixture, whereas perfusion with nonessential amino acids had no effect. When the essential amino acids were tested individually, only phenylalanine, methionine, and valine caused significant increases in pancreatic enzyme output; the effect of tryptophan was indeterminate. However, the pancreatic enzyme output was less in response to these three essential amino acids than to mixtures containing all of them.

The effect of phospholipase A on the calcium transport and the role of unsaturated fatty acids in ATPase activity of sarcoplasmic vesicles.

Abstract: 1 The cleavage of the β-ester bond of the phospholipids in the membranes of the sarcoplasmic reticulum by phospholipase A increases the permeability of the membranes for calcium whereby the ATP driven calcium storage is abolished. The activity of the calcium dependent ATPase remains unimpaired. The splitting products of the phospholipids which are composed of unsaturated fatty acids and prevailingly saturated lysolecithins are firmly attached to the membranal protein. They are removed from the protein by bovine serum albumin. The calcium dependent ATPase activity and the phosphoryl-transfer from ATP to the membranal protein are abolished thereby. 2 Unsaturated fatty acids restore the phosphoryl transfer reaction and the calcium dependent ATPase. Lysolecithin restores the ATPase activity nearly to the same extent but the phosphoryl transfer reaction is not reactivated. The accumulation of calcium is not restored either by unsaturated fatty acids or lysolecithin. 3 The calcium dependent ATPase reactivated by fatty acids is more sensitive towards prenylamine than the ATPase reactivated by lysolecithin. Prenylamine is bound to the vesicles activated by fatty acids whereas the vesicles reactivated with lysolecithin do not bind the drug.

Effects of chronic ethanol feeding on serum lipoprotein metabolism in the rat

Abstract: In rats, chronic ethanol feeding was found to enhance the postprandial hyperlipemia and to increase the incorporation of dietary palmitic acid-(3)H and intravenously injected L-lysine-(14)C into serum lipoproteins. The main increases of total amount, labeling, and specific activity of lipid and protein occurred in the d < 1.019 lipoprotein fraction. Fat absorption and the clearance of injected chylomicrons were not affected by ethanol feeding. Blocking of lipoprotein and chylomicron removal with Triton did not prevent the action of ethanol on serum lipids, indicating that the ethanol effect is not likely due to defective removal of lipids from the circulation. Ethanol enhanced the incorporation of chylomicron fatty acids into newly synthetized very low density lipoproteins, as shown by an increased reappearance of the fatty acid label into the lipids of this fraction after injection of palmitate-(14)C/glycerol-(3)H doubly labeled chylomicrons. These results indicate that alcoholic hyperlipemia is due, at least in part, to an increase in newly synthetized lipoproteins. The hyperlipemia produced by ethanol was accompanied by hepatic steatosis. The simultaneous production of fatty liver and hyperlipemia makes it unlikely that defective lipoprotein synthesis or secretion is a primary mechanism for the pathogenesis of the alcoholic fatty liver.

Biosynthese von 6‐Methylsalicylsäure

Abstract: An extract was prepared from Penicillium patulum grown in submerged culture, which converted acetyl-CoA and malonyl-CoA into 6-methylsalicylic acid in the presence of NADPH. The enzyme was very labile in the crude extract, but appeared stable after acetone precipitation. A 100-fold purification was achieved by ammonium sulfate fractionation, sedimentation in the ultracentrifuge, and sucrose-density gradient centrifugation. The enzyme was a single particle with a molecular weight of 1.1–1.5 × 106 as determined by gradient centrifugation with catalase and fatty acid synthetase as standards. In the first steps of purification, fatty acid synthetase from Penicillium patulum migrated with the methylsalicylic acid synthetase complex. A separation of the two enzyme systems was accomplished by sucrose-density gradient centrifugation. The purified enzyme represents a new multienzyme complex which shares several common properties with fatty acid synthetase. Methylsalicylic acid synthetase is inhibited by iodoacetamide and N-ethylmaleinimide. The incubation of enzyme with acetyl-CoA and malonyl-CoA in the absence of NADPH led to triacetic acid lacton. This indicates that in 6-methylsalicylic acid synthesis reduction occurs at the triacetic acid level before the final condensation with malonyl-CoA. Triacetic acid lacton was produced by the enzyme at 10% of the rate of 6-methylsalicylic acid synthesis in the complete system. This rate of lacton synthesis, however, is an order of magnitude greater than that catalysed by fatty acid synthetase. A possible explanation for this difference in behavior is given. Covalent linkage of substrates and intermediates to SH-groups of the protein during the synthesis of 6-methylsalicyslic acid is suggested. A reaction scheme leading to 6-methylsalicylic acid is proposed and the partial reactions of this synthesis are discussed with respect to similar reactions of fatty acid biosynthesis.

Brain lipid modifications induced by essential fatty acid deficiency in growing male and female rats

Abstract: —Essential fatty acid (EFA) deficiency initiated in rats prior to birth and continued for one year affects brain lipids to an extent which differs in the two sexes. It was found that: (1) Brain weight and lipid content were decreased in deficient conditions, especially in males. (2) Total phospholipids were present in lower concentrations, particularly in the deficient male brain, while the percentage of the major phospholipid classes-ethanolamine phosphoglyceride (EPG), choline phosphoglyceride (CPG) and serine phosphoglyceride (SPG) did not change. (3) Brain EPG, CPG and SPG had distinctive fatty acid patterns differing greatly in polyunsaturation content. PE acids of control females had elevated monoenes and reduced saturates in comparison with control males. This sex difference was lost in the deficient animals. (4) Polyunsaturated fatty acids of EPG, CPG and SPG were markedly changed in animals lacking dietary linoleic acid. Trienoic (C20 and C22) and docosapentaenoic acids were greatly increased, whereas arachidonic, docosatetraenoic and docosahexaenoic acids were much decreased. (5) In spite of the changes in fatty acid composition each of the three phospholipid classes maintained its particular level of unsaturation during EFA deficiency. (6) EPG aldehydes did not change appreciably in deficient conditions.

The polyunsaturated fatty acids of marine dinoflagellates.

Abstract: SYNOPSIS. Eight photosynthetic and one heterotrophic, marine dinoflagellates were cultured axenically in chemically defined media and their fatty acids characterized. Palmitic, octadecatetraenoic and docosahexaenoic were the most typical fatty acids. Photosynthetic forms also contained the polyunsaturates icosapentaenoic acid and α-linolenic acid, the latter as a relatively minor component. The galactolipids of one photosynthetic species, Glenodinium sp., were isolated and their fatty acids analyzed. Octadecatetraenoic acid was the predominant fatty acid, particularly of the monogalactosyl diglyceride fraction. The relationship of these findings to the body of knowledge of the photosynthesis-associated lipids of eucaryotic microbes and to the ecology of polyunsaturated fatty acids in marine food chains is discussed.

The essential fatty acids.

Abstract: Publisher Summary This chapter explains structural requirements, metabolism of action, and the role of the essential fatty acids. These acids are metabolized in ways common to other unsaturated fatty acids. In addition, the unsaturated acids possessing the 9, 12 double bond system (C18 acids) or the 11–14 double bond system (C20 acids) possesses special properties that are essential to the animal. Presumably, they function in esterified forms rather than as free fatty acids, and their essential roles may be determined by relative concentrations of phospholipids, glycerides, and sterol esters, which in turn seem to involve hormonal regulation. There is evidence to suggest that they are concerned, via phospholipids, in membrane integrity. This may be related to certain biochemical lesions that have been reported in connection with a deficiency of essential fatty acids in cases where membranes possess recognized biochemical activity, for example, in mitochondria. The essential fatty acids are the precursors of the prostaglandins, but the relationships of the latter to the classical deficiency symptoms is not certain and there is no evidence suggesting a relationship of this hormone family to the reported biochemical lesions of the deficiency.

Metabolism of long chain fatty acids in the rumen

Abstract: Publisher Summary This chapter discusses the metabolism of long-chain fatty acids in the rumen. The studies described in the chapter reveal the importance of veterinary problems in stimulating new interest in biochemical processes that might improve foods of animal origin and, thus, human nutrition. They have contributed to one of the most interesting areas of biochemical studies: the molecular basis of evolution. They have allowed the discovery of living biochemical fossils and have helped to elucidate the mechanisms of branched fatty acid biosynthesis and unsaturated fatty acid biohydrogenation. Studies on the origin of petroleum in association with studies on biological evolution show that branched-chain hydrocarbon structures derive from the corresponding fatty acid molecules. In fatty acid biohydrogenation, the enzyme responsible for the disappearance of a π bond probably represents a vestige, whose deep biological meaning is now hidden in the rumen, of the mechanisms of energy transformations of primitive organisms, when there was no oxygen in the atmosphere, at the beginning of life on earth.

Fatty acid composition of plasma and red cell phosphoglycerides in full term infants and their mothers.

Abstract: SUMMARY Methods have been adapted and their reproducibility tested for the determination of blood lipids and the fatty acid composition of the phosphoglycerides. The main lipid classes in 20 women from the south-western part of Sweden at term pregnancy and of umbilical cord plasma of their newborn infants were studied. Determinations were made of the fatty acid pattern of plasma phosphoglycerides and of cephalins and lecithin of red cells. The concentration of the major lipid classes in maternal and umbilical cord plasma agreed well with previously reported figures from other countries. The maternal plasma fatty acid pattern of phosphoglycerides was similar to that of adult males. The mothers and their infants had identical concentrations of the total sum of all polyunsaturated fatty acids in plasma phosphoglycerides, in red cell lecithin and in red cell cephalins. The infants' pattern differed from the mothers' by much lower concentrations of the parent fatty acids, linoleic and linolenic acids, and correspondingly increased concentrations of the more polyunsaturated fatty acids of the two series. The fatty acid composition in the red cell lecithin of mother and infant reflected that in the corresponding plasma. The cephalins contained more polyunsaturated fatty acids than the lecithin in both mothers' and infants' red cells. The study produced no biochemical evidence of an essential fatty acid deficiency in these newborns. The identical concentration of total polyunsaturated fatty acids in blood phosphoglycerides of mothers and infants in combination with the pronounced change in the ratio between the parent fatty acids and the highly polyunsaturated derivates, suggest a homeo-static regulation of the fatty acid composition of the blood phosphoglycerides.

Relationship between Fatty-Acid Composition of Platelets and Platelet Aggregation in Rat and Man RELATION TO THROMBOSIS

Abstract: Male rats fed a diet rich in butter or stearic acid presented a marked predisposition to endotoxin-initiated thrombosis. This was preceded by hypercholesterolemia, hypercoagulability, and an increased susceptibility of platelets to thrombin-induced aggregation. In contrast to this, feeding of corn oil or linoleic or oleic acids did not result in such marked changes in the blood or in severe thrombosis. Gas-liquid chromatographic analysis of total lipids of platelet and plasma indicated that the thrombogenic fat or fatty acid resulted in a highly significant increase, mostly in the platelets, of the ratio of saturated + monounsaturated to polyunsaturated fatty acids (S+M)/P. In patients who had suffered a myocardial infarction as compared with men without risk factors for coronary heart disease, an increase in the (S+M)/P in plasma and platelets was also observed. Among 17 active middle-aged businessmen, the five who presented signs of coronary heart disease also showed the highest susceptibility to thrombin-induced aggregation, but not to ADP or collagen. In these 17 subjects, the results of the thrombin aggregation could be correlated with the platelet (S+M)/P, but not with the plasma or platelet cholesterol. In both the rat and man, a high thrombotic tendency may be associated with a platelet hypersusceptibility to thrombin which, in turn, is related to changes in fatty-acid composition.

Influence of Duration of Cholesterol Feeding on Esterification of Fatty Acids by Cell-Free Preparation of Pigeon Aorta

Abstract: Influence of duration of cholesterol feeding on esterification of fatty acids and hydrolysis of cholesteryl esters was studied in cell-free preparations of aorta from White Carneau pigeons. Esterification of fatty acids required ATP and CoA; greater than 80% of the esterifying activity was located in the particulate fraction obtained by centrifugation at 105,000x g (after a preliminary centrifugation at 1000x g ). Fatty acids were incorporated most efficiently into phospholipid, primarily (82%) lecithin. Greater than 87% of the fatty acid was esterified at the 2-position. During 8 months of cholesterol feeding, incorporation of oleic acid into phospholipids and triglycerides increased relatively little (less than double that of controls); no changes were seen before 1 month. Esterification of oleic acid to cholesterol was increased after 2 weeks of cholesterol feeding (before gross lesions were seen), eventually reaching a maximum increase of 30- to 50-fold. Cholesterol was esterified by transfer of fatty acyl-CoA to cholesterol, a mechanism similar to that described for liver and adrenal cortex. Little if any cholesterol esterification occurred when lecithin labeled at the 2-position with oleic acid-l-14C was used as substrate. The relationship between duration of cholesterol feeding and hydrolysis of cholesteryl oleate could not be evaluated since results depend directly on an unknown extent of equilibration of substrate with pre-existing cholesteryl ester pools.

Composition of wheat‐flour lipids

Abstract: Lipids were extracted from a single sample of wheat flour using three solvent systems: ethanol–diethyl ether–water (2:2:1 by vol.); chloroform–methanol (2:1 by vol.); and water-saturated n-butanol. Analysis of the extracts and of residual lipid in the extracted flour showed that water-saturated n-butanol was the most efficient solvent. Wheat-flour lipids were extracted with water-saturated n-butanol and separated by chromatographic procedures into individual components. The lipid classes which were isolated and studied were steryl ester, free sterol, 6-O-acyl steryl glucoside, steryl glucoside, triglyceride, diglyceride, monoglyceride, free fatty acid, monogalactosyl diglyceride, 6-O-acyl monogalactosyl diglyceride, digalactosyl diglyceride, digalactosyl monoglyceride, monoglycosyl ceramide, diglycosyl ceramide, N-acyl phosphatidyl ethanolamine, N-acyl lysophosphatidyl ethanolamine, phosphatidyl ethanolamine, lysophosphatidyl ethanolamine, phosphatidyl choline, lysophosphatidyl choline, phosphatidyl serine and phosphatidyl inositol. Monogalactosyl monoglyceride was also tentatively identified. The quantitative distributions of the lipid classes were determined. Monoglycosyl ceramide contained small amounts of normal fatty acids (12:0–24:0) and large amounts of 2-hydroxy fatty acids (principally 16:0 and 20:0), with similar amounts of dihydroxy long-chain bases (18:0 and 18:1) and trihydroxy long-chain bases (18:0, 18:1, 19:0, 19:1, 20:0, 22:0). The principal sterols were identified as β-sitosterol, campesterol, and C28 and C29 saturated sterols. The fatty acids in the sterol lipids were principally 16:0 (50–60%) and 18:2 (28–30%) with small amounts of 16:1, 18:0, 18:1 and 18:3. The fatty acids in all the glycerides were principally 18:2 (51–84%) with lesser amounts of 16:0, 18:0, 18:1 and 18:3.