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[Essential fatty acids and their transformations in the animals (author's transl)].

The research of essential fatty acids biochemistry in Argentina was initiated approximately twenty years ago. These investigations together with the outstanding findings obtained in other countries proved the existence of different types of reactions. The essential fatty acids, linolenic and alpha linolenic, are converted by desaturation and elongation reactions in higher homologs building families of fatty acids. These reactions are regulated by dietary components, hormones, temperature and products of reaction. Retroconversion reactions transform the higher homologs, especially of 22 carbons back again to lower homologs avoiding beta oxidation. They are incorporated in the lipids to build the lipoproteic membranes increasing their fluidity. Specific acids are converted to prostaglandins that function as specific hormones.

Animals↗

[Effect of a diet with various amounts of essential fatty acid on the fatty acid spectrum of lipids in the kidneys in spontaneously hypertensive rats].

Fatty acid composition of phospholipids and triglycerides was studied by means of gas chromatography in kidney of rats with spontaneous hypertension, kept on rations containing various amounts of essential fatty acids. Deficiency of essential fatty acids caused an increase in content of oleic acid (18:1 omega 9) and of its metabolite--eucosetrienic acid (20:3 omega 9). Feeding of the animals with large amounts of linoleic (18:2 omega 6) and linoleic (18:3 omega 3) acids led to an increase of their content in kidney lipids as well as to elevation of prostaglandin precursors level. With an increase in deficiency of linoleic acid activity of delta 5-desaturation of its derivatives was decreased. Decrease in the rate of arterial pressure was observed in those spontaneously hypertensive rats, in kidney of which the content of linoleic, linoleic acids and eucosepentanic acid of the linoleic species (20:5 omega 3) was increased after the alimentary treatments.

Animals↗

[Metabolism of essential fatty acids and prostaglandins in the rat liver in chronic alcoholic intoxication].

Patterns of essential fatty acids and of prostaglandins metabolism were studied in liver tissue of rats which consumed 5% solution of ethanol as a single source of drinking material within 3, 6 and 9 months. Deficiency of essential fatty acids and a decrease in the content of prostaglandins occurred during development of chronic alcohol intoxication. Activity of PGE2 synthetase was decreased within 3 and 9 months and the activity of PGF2 alpha synthetase--within 9 months of the experiment. Activity of linoleyl-CoA-desaturase was decreased similarly in all the systems studied. The decrease in prostaglandins content found in liver tissue after long-term consumption of ethanol was due both to a deterioration in accessibility of the substrate for prostaglandin synthetase and to the decrease in activity of prostaglandin synthetases.

Alcoholism↗

Topical corn oil in the management of essential fatty acid deficiency.

Conflicting anecdotal reports about the efficacy of topical linoleate in managing essential fatty acid deficiency prompted this prospective study of 10 critically ill surgical patients receiving continuous total parenteral nutrition (TPN). Ten ml of corn oil (4800 mg of linoleate) were massaged into the skin daily commencing after 7.7 +/- 3.8 (mean +/- SD) days of fat-free intake. Plasma samples were obtained weekly. Total lipids were extracted and methylated, and fatty acids were quantitated by gas-liquid chromatography. The triene:tetraene ratio (20:3 omega 9/20:4 omega 6) increased progressively in patients despite corn oil therapy. In 89% of patients the ratio exceeded 0.2, which is diagnostic of essential fatty acid deficiency (EFAD). Topical application of corn oil does not prevent or treat EFAD in patients on TPN.

Administration, Topical↗

The effects of essential fatty acid supplementation by Efamol in hyperactive children.

Thirty-one children, selected for marked inattention and overactivity, were studied in a double-blind, placebo-controlled crossover study of essential fatty acid (EFA) supplementation. Subjects received the active treatment and placebo conditions for 4 weeks each and were assessed on a variety of cognitive, motor, and standardized rating scale measures. EFA supplementation (evening primrose oil; Efamol) resulted in significantly lower levels of palmitoleic acid (a nonessential fatty acid) and higher concentrations of dihomogammalinolenic acid, an EFA previously found to be deficient in some hyperactive children. Supplementation was also associated with significant changes on two performance tasks and with significant improvement to parent ratings on the subscales designated as Attention Problem and Motor Excess of the Revised Behavior Problem Checklist. However, a variety of eight other psychomotor performance tests and two standardized teacher rating scales failed to indicate treatment effects. When the experiment-wise probability level was set at .05, only 2 of 42 variables showed treatment effects. Baseline EFA concentrations appeared to be unrelated to treatment response. It was concluded that EFA supplementation, as employed here, produces minimal or no improvements in hyperactive children selected without regard to baseline EFA concentrations.

8,11,14-Eicosatrienoic Acid↗

Pathogenesis of diabetic neuropathy: the role of the n-6 essential fatty acids and their eicosanoid derivatives.

A substantial disturbance of the metabolism of the n-6 essential fatty acids exists in both human and experimental diabetes mellitus. Disturbances of the essential fatty acids and of the 1- and 2-series prostaglandins derived from them create a variety of microvascular, haemorheological, and other abnormalities leading to reduced blood flow and neural hypoxia which will in turn produce a cycle of hypoxia. Disturbance of the n-6 pathway may also result in functional and structural abnormalities of the axon, the myelin, and membrane-bound proteins such as enzymes and receptors. Metabolic disturbances identified previously may have a synergistic effect in enhancing these pathogenetic changes.

Diabetes Complications↗

[Does supplementation of essential fatty acids influence the visual acuity and cognitive function of term infants?].

BACKGROUND: Norwegian health authorities recommend supplementation of essential fatty acids such as cod liver oil to term infants from four weeks of age. The essential fatty acids are seen as contributing to optimal development of the visual acuity and cognitive functions. This study reviews recent research on this issue. MATERIAL AND METHODS: We assessed six randomized controlled trials, published in 1998 and 1999, of which two evaluated visual function and four cognitive development. Outcome were measured by a number of standardized tests. We compared the results from our review with results from a Cochrane review which evaluated six studies published from 1995 to 1997. RESULTS: Only one of the tests used in the visual acuity studies showed significant effect at three out of the four age-related points in time at which the test was administered. Only one of the tests used in the cognitive development studies showed significant effect. INTERPRETATION: The studies reviewed here are in accordance with previous research and do not provide evidence for the claim that supplementation with essential fatty acids as such is significant in order to achieve optimal visual function and cognitive development in healthy term infants.

Child Development↗

Effects of chronic ethanol treatment on lipid composition and prostaglandins in rats fed essential fatty acid deficient diets.

Rats of the third generation fed on a diet with 0.3 energy-% (low-essential fatty acids (EFA) or 3 energy-% (normal-EFA) essential fatty acids were given once-daily intraperitoneal injections of ethanol 3 g/kg or isocaloric glucose for 23 days. At the end of the experiment, organs were removed and their weight and lipid composition were determined. The postmortem accumulation of the prostaglandins PGE2, PGF2 alpha and 6-keto-PGF1 alpha was used to assess prostaglandin (PG) precursor availability in the organs. Ethanol was found to amplify the biochemical indicators of EFA-deficiency. The fatty acids 20:3 n-9 in brain phosphatidylethanolamine and phosphatidylinositol and 22:5 n-6 in brain phosphatidylethanolamine and phosphatidylserine were significantly higher in the ethanol group compared to the control group. In the kidney, the 20:3 n-9/20:4 n-6 ratio in phosphatidylinositol and phosphatidylserine was significantly higher in the ethanol group compared to the control group. The low-EFA animals had a lower output of urinary PGF2 alpha than the normal EFA animals. Chronic ethanol treatment gave a pronounced increase of urinary PGF2 alpha in both groups. Kidney levels of PGs were lower in the low EFA-animals. Chronic ethanol treatment gave a further decrease in kidney PGs. PG levels were the same in brains from low-EFA and normal-EFA animals with no effects of ethanol. The data are consistent with an increased utilization of EFA during chronic ethanol intoxication leading to a depletion of PG precursor stores in some but not all organs.

Alcoholism↗

The essential fatty acids.

In animal and human tissues, there are four families of fatty acids that are derived from the precursors palmitoleic, oleic, linoleic, and linolenic acids. Of these, linoleic and linolenic acids are essential dietary elements for humans and all higher animals. The four precursor fatty acids are metabolized (through desaturation and chain elongation) to form the long-chain polyunsaturated fatty acids. The principal fatty acids derived from linoleic acid are arachidonic acid, which contains four double bonds (tetraene) and dihomogamma linolenic acid, whereas products formed from linolenic acid are eicosapentaenoic acid and docosahexaenoic acid. The major products from palmitoleic and oleic acids are the 20 carbon fatty acids with three double bonds (triene). In the presence of adequate dietary amounts of essential fatty acids, tetraene products predominate in plasma. When the intakes of both linoleic and linolenic acids are low, triene formation is high and hence the triene/tetraene ratio in plasma is used to assess the index of essential fatty acid deficiency. The polyunsaturated fatty acids derived from essential fatty acids serve as cellular membrane phospholipid components which can influence the physicochemical characteristics of the lipid bilayer. Changes in membrane lipids can modify the mobility and function of a variety of membrane proteins which may result in altered cell/organ functions. Linoleic acid is specifically required in the skin to maintain the integrity of epidermal water barrier. The dihomogamma linolenic acid, arachidonic acid, and eicosapentaenoic acid are the precursors of eicosanoids which influence many cell processes and organ functions.(ABSTRACT TRUNCATED AT 250 WORDS)

Deficiency Diseases↗

Fat absorption in essential fatty acid deficiency: a model experimental approach to studies of the mechanism of fat malabsorption of unknown etiology.

Male rats were made deficient in essential fatty acids by feeding them a fat-free diet supplemented with 4% tripalmitin for 8-12 wk from the time of weaning. After feeding 0.5 ml of [(14)C]triolein or [(3)H]oleic acid, 72-hr stool recoveries of radioactivity were significantly greater in deficient rats than in chow-fed controls. Essential fatty acid deficiency did not reduce the absorptive capacities for triolein or for a medium-chain fat, trioctanoin, measured after 3 and 2 hr of maximal-rate duodenal infusion. In everted jejunal slices from essential fatty acid-deficient rats, uptake of micellar [(14)C]oleic acid at 0-1 degrees C was similar to that of controls, but the rate of incorporation of fatty acid into triglyceride after rewarming to 37 degrees C was significantly reduced. The specific activities of the microsomal esterifying enzymes, acyl CoA:monoglyceride acyltransferase and fatty acid CoA ligase in jejunal mucosa were 30% lower in essential fatty acid-deficient rats. However, the total microsomal enzyme activity adjusted to constant weight did not differ significantly in deficient rats compared with controls. After intraduodenal perfusion of triolein, accumulation of lipid in the intestinal wall was increased in the deficient rats. Because over 90% of the absorbed mucosal lipid was present as triglyceride, essential fatty acid deficiency appears to affect the synthesis or release of chylomicron lipid from the intestine. Analysis of regions of intestine showed that this delay in transport was most marked in the midportion of the small intestine.

Acyltransferases↗

Maternal adipose tissue, maternal and cord blood essential fatty acids and their long-chain polyunsaturated derivatives composition after elective caesarean section.

BACKGROUND: The essential fatty acids and their long-chain polyunsaturated derivatives (LC PUFAs) are important for the growth and maturation of the fetal organism. OBJECTIVE: The aim of a study was to assess the profile of the essential fatty acids and their LC PUFAs in the blood and adipose tissue of pregnant women and in the cord blood after elective caesarean section. DESIGN: The study group comprised 36 women and 38 their full-term babies born after elective caesarean section. In maternal adipose tissue, maternal blood (separately in plasma and erythrocytes) and cord blood (separately arterial and venous) composition of the fatty acids in total lipids was estimated with gas chromatography. RESULTS: In the maternal plasma and erythrocytes the weight percent content of linoleic acid and alfalinolenic acid was higher and of LC PUFAs was lower than in plasma and erythrocytes from the umbilical vein with the exception of EPA and DPA. In the maternal subcutaneous adipose tissue the content of alfalinolenic acid was higher and of linoleic acid and of LC PUFAs were lower than in maternal plasma and erythrocytes. There was no significant difference in the weight percent content of estimated acids between the venous and arterial umbilical blood. In the maternal plasma the weight percent content of linoleic acid, alfalinolenic acid and LC PUFAs was lower than in the maternal erythrocytes. CONCLUSION: Differences between maternal and cord blood essential fatty acids and their metabolites indicate that preferential placental transfer of n-6 and n-3 fatty acid metabolites or faster metabolic turnover of linolenic and arachidonic acids in the fetus than in mother is possible.

Adipose Tissue↗