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Although linoleic and linolenic acids have been known to be necessary for normal growth and dermal function since 1930, the omega 3 essential fatty acids (EFA) have not received much attention until recently. The two families of acids are metabolized by the same enzymes, making them competitive. Gross deficiencies of omega 6 plus omega 3 EFA have been observed in humans, induced by attempts at total parenteral nutrition (TPN) with preparations devoid of lipids. Deficiency of omega 3 acids has been induced by TPN containing high omega 6 and low omega 3 fatty acids. In natural human populations, a wide range of omega 3 and omega 6 proportions have been found, ranging from high omega 3 and low omega 6 content to low omega 3 and high omega 6 content, showing inverse correlation between sigma omega 6 and sigma omega 3. In humans with neuropathy or impairment of the immune system, significant deficits of omega 3 EFA have been measured.

Cholangiocytes, the epithelial cells that line intrahepatic bile ducts, are composed of plasma membranes with discrete apical (lumenal) and basolateral domains. While these domains are thought to contain different transporters, exchangers, channels, and receptors, no methodology currently exists for the isolation of these different membrane compartments. Thus, our aim was to develop a technique to isolated plasma membranes from cholangiocytes enriched in apical or basolateral domains. We isolate a cholangiocyte-enriched population of cells from rats 3 weeks after bile duct ligation (BDL), a maneuver which stimulates selective cholangiocyte proliferation. Using isopycnic centrifugation on linear sucrose gradients, we prepared a mixed cholangiocyte plasma membrane (MCPM) fraction from which we further generated separate apical and basolateral cholangiocyte plasma membrane (ACPM and BCPM, respectively). We characterized these fractions by specific marker enzyme assays, transmission electron microscopy (TEM), lipid analysis, anisotropy measurements, one- and two-dimensional gel electrophoresis, and quantitative immunoblots of the cystic fibrosis transmembrane conductance regulator (CFTR). Marker enzyme assays and TEM revealed that the MCPM fraction was essentially devoid of other organelles but was enriched approximately 70-fold in phosphodiesterase I, a general plasma membrane marker; the ACPM and BCPM were appropriately enriched in the respective apical and basolateral markers. TEM of ACPM and BCPM revealed homogeneous preparations of vesiculated membranes without contamination by other organelles. Lipid analysis, one- and two-dimensional gel electrophoresis, CFTR immunoblots, and anisotropy measurements showed unequivocal differences in lipid and protein composition and in fluidity between the ACPM and BCPM domains.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose tissue was obtained from six women undergoing liposuction twice at 6-mo intervals. Samples obtained bilaterally from abdomen, inner thigh, and outer thigh had fatty acids quantified by gas chromatography. There were no important differences between sides or over time. The saturates 14:0, 16:0, 18:0, and 20:0 were higher in abdominal adipose than in outer thigh (P < 0.002 for all); 16:1 and 18:1 omega 9 were lower in abdomen vs outer thigh (P < 0.01), whereas 18:1 omega 7 and 20:1 omega 9 were unchanged. Polyunsaturates 18:2 omega 6, 20:3 omega 6, and 20:4 omega 6 were higher in outer thigh than in abdomen (P < 0.06), and inner thigh values were intermediate. These changes in fatty acid composition resulted in lower mean triglyceride melting points from abdomen to inner thigh to outer thigh, and suggest that temperature may influence the selection process determining the variation in adipose fatty acid composition with anatomical location. Because the site-specific differences included essential fatty acids, selective uptake as well as potential differences in in situ fatty acid modification are indicated.

Diets rich in meat are claimed to contribute to the high tissue arachidonic acid (20:4 omega 6) content in people in Westernized societies, but there are very few direct data to substantiate this assertion. Because meat contains a variety of long-chain polyunsaturated fatty acids (PUFA) that are susceptible to oxidation, we initially examined the effect of cooking on the long-chain PUFA content of beef, and then determined the effect of ingestion of lean beef on the concentration of long-chain PUFA in plasma phospholipids (PL). First, we examined the effect of grilling (5-15 min) and frying (10 min) different cuts of fat-trimmed lean beef on the long-chain PUFA content. Second, we investigated the effect of including 500 g lean beef daily (raw weight) for 4 wk on the fatty acid content and composition of plasma PL in 33 healthy volunteers. This study was part of a larger trial investigating the effect of lean beef on plasma cholesterol levels. In the first two weeks, the subjects ate a very low-fat diet (10% energy) followed by an increase in the dietary fat by 10% each week for the next 2 wk. The added fat consisted of beef fat, or olive oil (as the oil or a margarine) or safflower oil (as the oil or a margarine). This quantity of beef provided 60, 230, 125, 140 and 20 mg/d, respectively, of eicosatrienoic acid (20:3 omega 6), 20:4 omega 6, eicosapentaenoic acid (20:5 omega 3), docosapentaenoic acid (22:5 omega 3) and docosahexaenoic acid (22:6 omega 3).(ABSTRACT TRUNCATED AT 250 WORDS)

Background: Although Wilson's disease is characterized by an accumulation of copper within hepatocyte lysosomes, the effects of excess copper on hepatic lysosomes are unknown. We studied the effects of excess copper on the structure, physicochemical properties, and pH of hepatocyte lysosomes using a rodent model. Methods: Rats were copper loaded with 0.125% copper acetate in water for 6 weeks. Copper was measured by atomic absorption spectrophotometry. Morphology was studied by electron microscopy. Lysosomal membrane fluidity was studied by fluorescence polarization, and lipid composition was determined by gas chromatography. Hepatocyte lysosomal pH was determined by flow cytometry. Results: Copper overload resulted in a 10-fold increase in hepatic copper. Hepatocyte lysosomes were enlarged and abnormally shaped with a 27-fold increase in copper, increased in vitro fragility, and decreased lysosomal membrane fluidity. Thiobarbituric acid reactive substances, a measure of lipid peroxidation, doubled in isolated lysosomal membranes. Polyunsaturated fatty acids increased, saturated fatty acids decreased, and membrane content of selected fatty acids was modified after copper overload. Lysosomal pH increased from 4.67 ± 0.02 to 4.87 ± 0.02. Conclusions: Copper overload causes alterations in lysosomal morphology, increases lysosomal fragility, decreases membrane fluidity, alters membrane fatty acid composition, and increases lysosomal pH. Copper catalyzed lipid peroxidation represents the likely mechanism for these alterations.

Serum NEFA profiles in Reye's syndrome are reportedly unique with a disproportionate percent made up of polyunsaturated fatty acids some of which are not ordinarily found in the serum. This pattern is also reflected in the serum triglyceride composition as well. As the liver is probably the sole source of the serum triglyceride in Rye's syndrome because patients are vomiting or in coma, the fatty acid acid composition of the liver triglyceride was examined for insight regarding the lipid abnormalities in this disease. Palmitic acid (16:0) and the sum of all the saturated fatty acids in the liver triglycerides were significantly decreased whereas the sum of the monoenoic fatty acids and the products of delta 9 desaturase activity were increased in Reye's samples. When these data were compared to the fatty acid composition of the serum triglyceride from a separate cohort of Reye's and control subjects, certain inferences regarding hepatic delta 9, delta 6, delta 5, and delta 4 desaturase activities and the elongases can be drawn from the liver and serum triglyceride fatty acid profiles which are unique. Collectively, these data reflect considerable intrahepatic fatty acid desaturation and elongation activity and/or acyl transfer from lipid to lipid of various polyunsaturated fatty acids in Reye's syndrome.

Linoleic acid (18:2 omega 6) and linolenic acid (18:3 omega 3) are precursors of two series of essential fatty acids (EFA) formed by alternate desaturations and elongations. In EFA deficiency (EFAD), oleic acid (18:1 omega 9) and palmitoleic acid (16:1 omega 7) undergo the same reactions to form polyunsaturated fatty acids (PUFA) of other structures. Partially hydrogenated soybean oil (PHSO) contains isomeric 18:1 acids that can be converted to unusual isomers of 18:2 by liver microsomes. To test whether 18:2, 20:3, and 20:4 of unusual structure occur in phospholipids as a consequence of EFAD or ingestion of PHSO, rats were fed corn oil, an EFA-deficient diet, or PHSO to provide isomeric 18:1 acids. At 2.5 months the phospholipids were isolated from livers and converted to methyl esters, and the 18:2, 20:2, 20:3, and 20:4 fractions were isolated. The 18:2 and 20:2 fractions were ozonized, and, by using a computer solution of simultaneous equations, the structures and proportions of each isomer were calculated. The 20:3 and 20:4 fractions were analyzed by ozonolysis and capillary gas chromatography. When corn oil was fed, the major isomer in each group was 9,12-18:2, 11,14-20:2, 8,11,14-20:3, and 5,8,11,14-20:4. Patterns in EFAD- and PHSO-fed groups were more diverse, with large proportions of unusual isomers. Feeding EFA-deficient diet and PHSO induced measurable amounts of unusual PUFA at each step of the cascade, and these PUFA may compete in metabolism of normal PUFA and are substrates for oxidative formation of autacoids of unknown structures and function.

The human undergoing rapid and sustained weight loss by very low calorie dieting (VLCD) derives the majority of daily energy needs from adipose fatty acids. To evaluate the rates of metabolic utilization of individual fatty acids in humans, two groups of adult women outpatients were studied during major weight loss by VLCD. The diets used were either food or formula, providing the recommended dietary allowance for minerals and vitamins, with fat contents of 2–20 g/d. Group 1 consisted of 10 subjects [initial body mass index (BMI) 32.7, 157% of ideal body weight (IBW)] with a mean loss of 17.7 kg in 3–5 months. Group 2 consisted of 14 subjects (initial BMI 36.7, 167% of IBW) with a mean loss of 25.6 kg in 4–5 months. Adipose tissue biopsies were obtained by needle aspiration from Group 1 before and after weight loss and from Group 2 before, at the midpoint, and after weight loss. With weight loss in Group 1, the adipose tissue content of 18∶1ω9, 18∶2ω6, and 20∶4ω6 did not change, but 18∶3ω3 fell (0.67 to 0.56 wt%, p

We administered borage seed oil (9 capsules/day) for 12 weeks to 7 normal controls and to 7 patients with active rheumatoid arthritis. The therapy provided 1.1 gm/day of gamma-linolenic acid (GLA). GLA administration resulted in increased proportions of its first metabolite, dihomo-gamma-linolenic acid (DGLA), in circulating mononuclear cells. The ratios of DGLA to arachidonic acid and DGLA to stearic acid increased significantly in these cells. Significant reductions in prostaglandin E2, leukotriene B4, and leukotriene C4 produced by stimulated monocytes were seen after 12 weeks of GLA supplementation. The antiinflammatory effects of GLA administration observed in animal models, and the apparent clinical improvement experienced by 6 or 7 rheumatoid arthritis patients given borage seed oil in this open, uncontrolled study may be due in part to reduced generation of arachidonic acid oxygenation products.

Epidemiological and animal-based investigations have indicated that the development of skin cancer is in part associated with poor dietary practices. Lipid content and subsequently the derived fatty acid composition of the diet are believed to play a major role in the development of tumorigenesis. Omega 3 (omega3) fatty acids, including docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), can effectively reduce the risk of skin cancer whereas omega 6 (omega6) fatty acids such as arachidonic acid (AA) reportedly promote risk. To investigate the effects of fatty acids on tumorigenesis, we performed experiments to examine the effects of the omega3 fatty acids EPA and DHA and of the omega6 fatty acid AA on phorbol 12-tetradecanoate 13-acetate (TPA)-induced or epidermal growth factor (EGF)-induced transcription activator protein 1 (AP-1) transactivation and on the subsequent cellular transformation in a mouse epidermal JB6 cell model. DHA treatment resulted in marked inhibition of TPA- and EGF-induced cell transformation by inhibiting AP-1 transactivation. EPA treatment also inhibited TPA-induced AP-1 transactivation and cell transformation but had no effect on EGF-induced transformation. AA treatment had no effect on either TPA- or EGF-induced AP-1 transactivation or transformation, but did abrogate the inhibitory effects of DHA on TPA- or EGF-induced AP-1 transactivation and cell transformation in a dose-dependent manner. The results of this study demonstrate that the inhibitory effects of omega3 fatty acids on tumorigenesis are more significant for DHA than for EPA and are related to an inhibition of AP-1. Similarly, because AA abrogates the beneficial effects of DHA, the dietary ratio of omega6 to omega3 fatty acids may be a significant factor in mediating tumor development.

Cholangiocytes, the epithelial cells that line intrahepatic bile ducts, are composed of plasma membranes with discrete apical (lumenal) and basolateral domains that contain different channels, transporters, and receptors. In recent work, we developed a long-term, primary culture system of normal rat cholangiocytes (NRC). Our aims here were to prepare and characterize apical and basolateral plasma membrane vesicles from NRC. Using serial isopycnic centrifugation on sucrose gradients, we generated separate apical and basolateral plasma membrane vesicles. We characterized these vesicles by transmission electron microscopy, specific marker enzyme assays, and immunoblotting; we also determined the percentage of sealed vesicles and their intravesicular volume and sidedness using biochemical approaches. Our results showed that vesicles derived from the apical and basolateral plasma membrane domains of NRC were highly purified, predominately sealed, right-side-out vesicles that differed in size and lipid and protein composition. This experimental model represents a novel tool that will be useful for additional functional studies on the channels, transporters, and receptors differentially distributed in the plasma membrane of biliary epithelia.

Several closely related long-chain omega-phenylalkanoic and omega-phenylalkenoic acids occur in the seed lipids of genera of the subfamily Aroideae of the Araceae. One, 13-phenyltridecanoic acid, is a major component. This is the first report of these acids in plant lipids. Their presence in only one subfamily may indicate that the Araceae is diphyletic.

In 1943 when I began research with Professor George O. Burr on the chemistry of essential fatty acids (EFA), there were no methods to measure individual fatty acids (FA) in tissue lipids. Using the new Beckman (Fullerton, CA) DU spectrophotometer, instrument #6, we explored the use of ultraviolet spectra in the study of auto-oxidation of individual FA, and found that the auto-oxidation of the polyunsaturated fatty acids (PUFA) induced drastic elevations of absorption in the ultraviolet range (Holman et al., 1945). Holman and Burr (1948) then exploited the alkaline conjugation reaction, at high temperature, to induce conjugation of the double bonds of the common essential FA. The fully conjugated polyenoic acids had distinctive absorption bands, which made it possible to distinguish and measure the content of the originally nonconjugated, methylene interrupted diene-, triene-, tetraene-, pentaene-, and hexaene-acids present in biological lipids. Using this new analytical method, we learned next that the lack of PUFA in the diet lowered the amount of arachidonic acid in liver lipids, and that a triene acid, not present in animals fed EFA, appeared in those lipids. Supplementation with corn oil elevated the arachidonic acid, but supplementation with cod liver oil elevated the pentaenoic and hexaenoic acids in all tissues analyzed by Rieckehoff et al. (1949). The dietary fat influenced the lipid composition of the animal!

UNLABELLED Essential fatty acid (EFA) deficiency is a predisposing factor for pulmonary infection with Staphylococcus aureus and Pseudomonas aeruginosa, the two major pathogenic microorganisms in cystic fibrosis (CF). OBJECTIVE The goal of this study was to investigate the essential fatty acid status of CF patients from infancy to 20 years old. MATERIALS AND METHODS Plasma fatty acid profiles for phospholipid (PL) were determined for cord (n = 6), 4 months (n = 40), 16 months (n = 25), 3 y (n = 8), 5-10 y (n = 10), and 10-20 y (n = 10) aged CF patients and compared to their respective control; cord (n = 22), 1-36 months (n = 38) and adult (n = 100). Significance was established by Student's t-test (p < 0.05). RESULTS The plasma PL fatty acid profile for all CF patients, except cord, revealed consistent deficiency in omega 3 and omega 6 EFAs. These deficiencies were most marked at infancy and more pronounced for patients with meconium ileus. CONCLUSIONS AND RELEVANCE EFA deficiency may contribute to the predisposition of CF infants to develop respiratory disease and to the excess cytotoxic activity found in bronchoalveolar lavage fluid at 2 months of age in the majority of screened infants.

The profiles of fatty acids (FAs) of plasma phospholipids (the compartment reflecting the essential FA status of tissue lipids), nonesterified FAs (the precursor pool for autacoid synthesis), urine protein excretion, and glomerular filtration rate were measured before and after supplementation with fish oil in 15 patients with immunoglobulin A nephropathy. In the FA profiles, there was deficient 18:3 omega 3 (alpha-linolenic acid), the parent compound of omega 3 polyunsaturated FA, and deficient chain elongation products of both omega 3 and omega 6 polyunsaturated FAs with replacement by saturated and monounsaturated short-chain, odd-chain, and branched-chain FAs, producing significant loss of omega 3 FA. These alterations indicate nutritional or functional (omega 3) and metabolic (omega 6) deficiencies. Additionally, the mean melting point of the FAs was significantly increased, implying an inherent decrease in cell membrane fluidity. Enhancement of 20: 5 omega 3 (eicosapentaenoic acid) and 22:6 omega 3 (docosahexaenoic acid) and suppression of 20:4 omega 6 (arachidonate) after supplementation with fish oil were accompanied by important decreases in proteinuria and improved glomerular filtration rate. Omega-3 polyunsaturated FAs may favorably influence immunoglobulin A nephropathy through a modulation of the pathologic actions of the omega 6 eicosanoids and other diverse actions on various mediators produced by an initial immune injury.

Objective: The aim was to determine if reduced heart lipid peroxidation in turkeys with two forms of dilated cardiomyopathy, previously reported, was related to an alteration in the lipid composition of the ventricle. Methods: Myocardial lipid composition was measured in turkeys with two types of dilated cardiomyopathy. Twenty six turkeys with naturally occurring dilated cardiomyopathy, six with furazolidone induced dilated cardiomyopathy, and 18 age matched control birds were used at 1 day, 9-10 days, and 38-78 days of age. Left ventricular fatty acid composition of the phospholipid, triglyceride, free fatty acid, and cholesterol ester fractions was analysed using gas chromatography. Results: Significant age related changes were identified in the fatty acid composition of the heart. In the phospholipid fraction, linoleic acid (18:2ω6) values increased with age, while arachidonic acid values decreased. The saturated to unsaturated fatty acid ratio in control hearts was unchanged as a function of age in the phospholipid fraction. In the triglyceride fraction, however, this ratio decreased substantially between newly hatched and nine day old birds and then markedly increased in two month old controls. There was a striking alteration in the saturated to unsaturated fatty acid ratio in the triglyceride fraction of 2 month old cardiomyopathic birds; this ratio was markedly increased in the furazolidone induced cardiomyopathic turkey hearts (5.14 v 2.79 in controls) and markedly diminished (ie, 0.97 to 1.21) in the spontaneously cardiomyopathic turkeys. A significant increase in myristic (14:0) and decrease in linoleic (18:2ω6) acid concentration in the furazolidone group v control and a marked decrease in myristic and increase in linoleic acid concentrations in the spontaneously cardiomyopathic group v controls was present. Conclusions: (1) There is an age related alteration in the fatty acid composition of control turkey hearts. (2) Previously identified reduced lipid peroxidation in furazolidone induced and spontaneous cardiomyopathy in turkeys does not appear to be related to reduced concentration of polyunsaturated fatty acids. (3) The two forms of dilated cardiomyopathy are associated with markedly disparate alterations in the concentration of polyunsaturated fatty acids in the triglyceride fraction of 1-2 month old turkey hearts. The changes may be related, in part, to the pathogenesis in these two different forms of dilated cardiomyopathy. Cardiovascular Research 1994; 28 :407-413

Retinitis pigmentosa (RP) is a hereditary retinal degeneration of unknown etiology, resulting in progressive night blindness, loss of peripheral vision, abnormal retinal pigmentation and reduced electroretinographic response. Docosahexaenoic acid (22:6 omega 3) is found in high concentration in the rod outer segment membranes of the retina. Previous reports of low 22:6 omega 3 in blood lipids or phospholipids in RP patients prompted us to evaluate the complete fatty acid (FA) profiles of plasma phospholipids (PL), cholesteryl esters, triglycerides (TG) and nonesterified fatty acids (NEFA) in ten patients with RP. In the PL fraction, we found significantly depressed levels of 22:6 omega 3, 22:5 omega 3, total omega 3, 22:5 omega 6, 22:4 omega 6 and total omega 6 polyunsaturated FA (PUFA), and elevated total saturated acids. Plasma TG showed normal levels of PUFA, normal total saturated FA and total monounsaturated FA. The NEFA fraction showed significant elevation in total saturated FA with depressed total omega 6 PUFA. Evidence is accumulating mulating that RP is associated with abnormal PUFA and lipid metabolism.

While hemochromatosis is characterized by sequestration of iron-protein complexes in hepatocyte lysosomes, little is known about the effects of excess iron on these organelles. Therefore, we studied the effects of experimental iron overload on hepatocyte lysosomal structure, physicochemical properties, and function in rats fed carbonyl iron. A sixfold increase (P less than 0.0001) in hepatic iron and a fivefold increase in lysosomal iron (P less than 0.01) was observed after iron loading; as a result, hepatocyte lysosomes became enlarged and misshapen. These lysosomes displayed increased (P less than 0.0001) fragility; moreover, the fluidity of lysosomal membranes isolated from livers of iron-loaded rats was decreased (P less than 0.0003) as measured by fluorescence polarization. Malondialdehyde, an end product of lipid peroxidation, was increased by 73% (P less than 0.008) in lysosomal membranes isolated from livers of iron-overloaded rats. While amounts of several individual fatty acids in isolated lysosomal membranes were altered after iron overload, cholesterol/phospholipid ratios, lipid/protein ratios, double-bond index, and total saturated and unsaturated fatty acids remained unchanged. The pH of lysosomes in hepatocytes isolated from livers of iron-loaded rats and measured by digitized video microscopy was increased (control, 4.70 +/- 0.05; iron overload, 5.21 +/- 0.10; P less than 0.01). Our results demonstrate that experimental iron overload causes marked alterations in hepatocyte lysosomal morphology, an increase in lysosomal membrane fragility, a decrease in lysosomal membrane fluidity, and an increase in intralysosomal pH. Iron-catalyzed lipid peroxidation is likely the mechanism of these structural, physicochemical, and functional disturbances.

In a group of 19 normal pregnant women, plasma lipids were extracted, phospholipids were isolated, and the fatty acid (FA) compositions were measured by capillary gas chromatography. Blood samples were taken at 36 wk, at labor, and at 6 wk postpartum. The FA profiles showed deficiencies of omega 6 and omega 3 FA (omega indicating the length of the terminal saturated chain), the latter more severe, at all three times. Mean melting point (MMP) was calculated for each sample as an index of "fluidity" based upon all FA present. MMP varied linearly with total polyunsaturated FA and with double bond index, current measures of "fluidity" and essential FA status. MMP was elevated 9-11 degrees C in plasma phospholipids of women during pregnancy and labor and postpartum. Lactating mothers showed less recovery from the deficiencies than did the nonlactating mothers, but neither approached normal at 6 wk. The changes seen in phospholipid profiles suggest a significant transfer of omega 3 and omega 6 polyunsaturated FA from the mother to the fetus. These FA are essential for normal fetal growth and development; their relative deficiency in maternal circulation suggests that dietary supplementation may be indicated.

Since an omega 3 fatty acid (FA) diet may have beneficial effects in inflammatory processes, we tested the hypothesis that the physiologic response to sepsis could be modified by altering the eicosanoid precursor pool via an omega 3 FA diet. Two groups (n = 8) of pigs were prefed for 8 days either an omega 3 FA or an omega 6 FA diet (Weaner Pig Feed with either menhaden or corn oil to produce a eucaloric feed with 15% fat) and then injected with live Escherichia coli. The omega 3 FA diet increased the concentration of eicosapentainoic acid (EPA, 20:5 omega 3) in plasma lipids, and increased the ratio of EPA to arachidonic acid (AA, 20:4 omega 6) in platelets from 1:20 to 1:1 over the 8 days. Following the injection of bacteria, there was a fall in PaO2 and blood pressure that was attenuated (p less than 0.05) by the omega 3 FA diet. The omega 3 FA diet, compared to the omega 6 FA diet, also attenuated the rise in thromboxane B2 (3.0 +/- 1.1 vs 12.9 +/- 5.7 ng/mL) and 6 keto-PGF1 alpha (0.8 +/- 0.5 vs 1.7 +/- 1.1 ng/mL) associated with bacteremia. We conclude that dietary omega 3 FA attenuated the physiologic response to sepsis, possibly by modifying arachidonic acid metabolism.

Total parenteral nutrition with an amino acid-glucose solution has previously been shown to decrease rat hepatic drug metabolism compared with drug metabolic activity observed in rats receiving the same solution enterally and chow-fed animals. Because changes in membrane fluidity and lipid composition are reported to influence activity of a number of liver enzymes, effects of parenteral and enteral nutrition on hepatic microsomal membrane fluidity and lipid composition were assessed and compared with hepatic mixed-function oxidase activity. Both parenteral and enteral hyperalimentation produced a significant decrease in microsomal membrane fluidity (fluorescence anisotropy = 0.155 +/- 0.003 in both experimental groups versus 0.129 +/- 0.003 for microsomes from chow-fed animals). However, meperidine demethylase activity was significantly decreased compared with chow-fed experiments only in hepatic microsomes from parenterally hyperalimented animals, whereas ethoxyresorufin deethylase activity was significantly reduced only in the enteral-nutrition group. Inclusion of lipid in the parenterally administered hyperalimentation solution normalized microsomal membrane fluidity and lipid profile to those of chow-fed animals but did not increase hepatic meperidine demethylation. Both parenteral and enteral nutrition produce significant changes in physical state and lipid composition of rat hepatic microsomal membranes, but these changes are not responsible for the altered hepatic drug metabolism observed during hyperalimentation.

The accumulation and depletion of trans 18:1 acids in the sciatic nerve phospholipids was studied in rats fed a diet containing 18% partially hydrogenated soybean oil of which 45% was trans 18:1. The nerve phospholipid of rats fed partially hydrogenated soybean oil beginning at weaning age reached a maximum incorporation of trans 18:1 of 0.8% in 4 weeks; whereas the nerve phospholipid of 18-day-old pre-weanling pups of mothers fed the partially hydrogenated soybean oil diet since their weaning contained 3.3% trans 18: l. The trans content decreased rapidly after the weaning of these second-generation rats to a steady-state level 50% higher than the maximum level reached in the first generation. Upon removal of partially hydrogenated soybean oil from the diet, the trans 18:1 of nerve phospholipid decreased much more slowly than from liver or heart phospholipid. Essential fatty acid deficiency had no influence on incorporation or removal of trans 18:1 in nerve phospholipid. The accumulation and depletion of frans 18:1 in nerve phospholipid of second-generation partially hydrogenated soybean oil-fed rats parallelled the changes of polyunsaturated fatty acids and was quite different from the changes observed in 18:0 and cis 18:1. Polyunsaturated fatty acids increased in nerve phospholipid from second but not first-generation rats fed partially hydrogenated soybean oil and declined rapidly when partially hydrogenated soybean oil was removed from the diet.

Ferrochelatase is an enzyme bound to the inner mitochondrial membrane, which is important in heme biosynthesis. Activity of purified ferrochelatase is affected by the presence of certain fatty acids. In the present study, we examined whether the activity of ferrochelatase is altered by dietary manipulation of the composition of mitochondrial membrane phospholipid fatty acylgroups. Rats were fed diets containing triolein, safflower or menhaden oil as 5% (w/w) of the diet. After 3 weeks, the animals were killed and liver mitochondria were isolated. Phospholipid fatty acid composition and ferrochelatase activity were assayed in the isolated mitochondria. Marked differences were seen. The proportion of oleic acid was highest in the triolein oil-fed group, that of linoleic and arachidonic acid was highest in the safflower oil-fed group and the proportion of eicosapentaenoic acid was highest in the menhaden oil-fed group. Ferrochelatase activity was greatest in the triolein oilfed group and lowest in the menhaden oil-fed group regardless of whether the mitochondria were intact, sonicated or sonicated and treated with Tween 20. Mixing of mitochondria from menhaden oil-fed rats with triolein oil resulted in a significant increase in ferrochelatase activity. Membrane fluidity and activities of the mitochondrial membrane enzymes succinic dehydrogenase and cytochrome oxidase did not differ among the groups. We conclude that dietary manipulation of mitochondrial membrane phospholipid fatty acyl group composition can directly modulate hepatic ferrochelatase activity. This has potential application in the treatment of protoporphyria, the genetic disorder in which ferrochelatase activity is deficient.

A cell-free particulate preparation from Butyrivibrio fibrisolvens was used to study the relative rates of isomerization of all cis, cis-methylene-interrupted isomers of octadecadienoic acid. Only two isomers were found to be substrates, the 9,12-isomer was isomerized at 41 ± 4 μmol/min per mg protein, and the 2,5-isomer at 11 ± 1 μmol/min per mg. The product of the isomerization of the 2,5-isomer had an ultraviolet absorption maximum at 233 nm indicating that it was the 3,5-isomer. The isomerization of the 2,5-isomer was studied in detail. Its rate of isomerization was linear with protein concentration up to 0.047 mg/ml, and was linear with substrate concentration up to 48 μM. The pH optimum was 6.8. Below pH 6, the substrate was also subject to spontaneous isomerization. The inhibition of isomerization of the 9,12-isomer by the other isomers was studied. Those isomers in which the double bonds are close to the carboxyl group were the most effective inhibitors. The preparation was also found capable of hydrogenating the conjugated diene product from the 2,5-isomer to a monoene after prolonged incubation.

The influences of zinc-deficiency and reduced food intake on levels of polyunsaturated fatty acids (PUFA) of phospholipids (PL) of lymphoid and nonlymphoid tissues were studied. Weanling male Long-Evans rats were fed ad libitum either a zinc-deficient (ZD) or a zinc-adequate (ZA) diet for 21 days. A pair-fed (PF) group was given the ZA diet in an amount equal to that consumed on the previous day by the ZD group. Linoleic acid (18:2ω6), 18:3ω6 and 20:3ω6 were either equivalent or significantly higher, but arachidonic acid (20:4ω6) and 22:5ω6 were either equivalent or significantly lower in tissues of ZD and PF rats compared to ZA rats. Total ω6 acids and metabolites were either equivalent or significantly lower in tissues of ZD and PF rats compared to ZA rats. In contrast, total ω3 acids and metabolites, and total ω9 acids and emtabolites were either equivalent or significantly higher in ZD and PF rats compared to ZA rats. Changes in PUFA patterns of lymphoid and nonlymphoid tissues of ZD rats were influenced by reduced food intake.

Fatty acid patterns of the serum lipids were measured in 17 children with Reye's syndrome (RS). Serial measurements of total serum free fatty acids (FFA) showed that levels were increased during RS and, after recovery, were significantly lower in the patients who survived. Fatty acid patterns of serum FFA, triglycerides, and phospholipids in patients with RS were significantly different from those in controls. In RS the polyunsaturated fatty acid content of phospholipids was less than control values; in the FFA, it was higher. This was consistent with the possible involvement of increased phospholipase activity. The increase in polyunsaturated fatty acids in FFA, the precursors of prostaglandins, suggests that a grossly disturbed prostaglandin pattern may occur in RS. These changes in lipid metabolism may be related to the abnormal hepatic and neurological functions observed in RS.

An approach to the analysis of 55 possible nonconjugated positional isomers of octadecadienoic acid is described and tested with mixtures of individual synthetic methyl esters. In the first example, by ozonolysis a seven-component mixture consisting of cis,cis 5,12-, 6,10-, 6,11-, 6,12-, 7,12-, 8,12-, and 9,12-octadecadienoates was converted to aldehydes, aldehyde-esters and dialdehydes. These fragments were separated on a 50 m X 0.2 mm free fatty acid phase (FFAP) vitreous silica capillary column. Equations for an arbitrarily restricted 12 X 15 matrix of linear simultaneous equations and a computer solution of the matrix provided the composition of the initial methyl octadecadienoate mixture. The power and significance of this method became apparent with the observation that only two of the seven isomers in the known mixture were resolved as single peaks by state-of-the-art capillary gas chromatography, but all seven were identified and estimated with acceptable error by the ozonolysis-capillary gas chromatography-computer procedure. In a generalized approach to the analysis of the 55 possible nonconjugated isomers, a computer program selects the appropriate matrix of linear simultaneous equations based on the aldehyde data supplied by the analyst. Twenty of 21 combinations of seven isomeric esters taken five at a time have been analyzed to assess the efficiency of the method. To illustrate applicability at this stage of development, the method has been used to analyze the diene products of the hydrazine reduction of gamma-linolenic acid and the diene products from the biological desaturation of isomeric monoenes.(ABSTRACT TRUNCATED AT 250 WORDS)

The inhibitory effects of the positional isomers of trans-18:1 acids on the desaturation of palmitic acid to palmitoleic (delta 9-desaturase), linoleic to gamma-linolenic (delta 6-desaturase) and eicosa-8,11,14-trienoic to arachidonic acid (delta 5-desaturase) were investigated. These trans-18:1 acids were found to be inhibitory for the microsomal delta 6-, delta 9- and delta 5-desaturases of rat liver. The position of the double bond in the trans-18:1 acids seems to be important in determining the degree of inhibition. At inhibitor/substrate ratio of 3:1, the delta 6-desaturase was most strongly inhibited by trans-delta 3, -delta 4, -delta 7 and -delta 15-18:1 isomers, whereas the delta 9-desaturase was most strongly inhibited by trans-delta3, -delta 5, -delta 7, -delta 10, -delta 12, -delta 13 and -delta 16 isomers. At inhibitor/substrate ratio of 6:1, the delta 5-desaturase was most strongly inhibited by delta 3-, delta 9-, delta 13- and delta 15-isomers. When 18:0 was added to the incubations of 16:0, 18:2 and 20:3 at the same I/S ratios used for the trans-18:1 acids, weak inhibition for delta 9- desaturase and no inhibition for delta 5- and delta 6-desaturases was observed.

The effects of dietary polyunsaturated and saturated fats upon several metabolic phenomena were studied in rats. These included phospholipid (PL) levels in unstimulated spleen lymphoid cells (SLC) and serum; in vitro proliferation of unstimulated SLC from the two groups of rats; the influence of mitogenic concanavalin-A (Con-A) on in vitro proliferation of SLC from the two groups of rats; and the influence of serum from the two groups of rats on SLC proliferation. Weanling male Long-Evans rats were fed ad libitum either a polyunsaturated fatty acid (PUFA)-adequate (safflower oil, SO) or PUFA-deficient (coconut oil, CNO) diet for 21 days. Growth was significantly less in the CNO group than in the SO group. Food intake was not different for the dietary groups. Unstimulated SLC and serum of CNO rats showed changes in fatty acid composition of PL typical of tissue PL in essential fatty acid-deficient (EFA-D) rats. Unstimulated SLC from the two groups cultured in medium containing serum from the same groups showed equivalent rates of in vitro proliferation. In vitro proliferations of SLC were influenced: by the dietary source of SLC but not by the dietary source of serum, used in the culture medium, when the cells were stimulated by suboptimal doses of Con-A; by the dietary source of serum but not by the dietary source of SLC when the cells were stimulated by the optimal dose of Con-A; and by an interaction between source of SLC and serum, when the cells were stimulated by a supra-optimal dose of Con-A. The present study indicates that in vitro proliferation of SLC from PUFA-adequate and PUFA-deficient rats is influenced by both the dietary source of serum used in the culture medium and the concentration of Con-A used for stimulation of the SLC.

Biotin deficiency associated with total parenteral nutrition is an emerging clinical problem; criteria for diagnosis and dosage for treatment are unclear. We have diagnosed and successfully treated biotin deficiency in three patients. Each patient had alopecia totalis, hypotonia, and developmental delay. Two developed the characteristic scaly periorificial dermatitis; one had only an intermittent scaly rash on the cheeks and occipital scalp. Zinc and essential fatty acid supplements were adequate; serum zinc levels and triene/tetraene ratios confirmed sufficiency of these nutrients. None of the patients received biotin prior to diagnosis, and each had decreased excretion of urinary biotin and increased urinary excretion of organic acids diagnostic of deficiency of two biotin-dependent enzymes (methylcrotonyl-coenzyme A carboxylase and priopionyl-coenzyme A carboxylase). Only one patient had a plasma biotin concentration below the normal range (Ochromonicas danica assay). The rash, alopecia, and neurologic findings responded dramatically to biotin therapy (100 micrograms/day in all patients; an initial larger dose of 1 mg/day for 1 week plus 10 mg/day for 7 weeks in one patient), and did not recur. However, abnormal organic acid excretion persisted in one patient who did not receive the larger dose. We conclude that plasma biotin concentration does not reflect biotin status in all cases and speculate that the biotin supplement currently recommended for pediatric patients (20 micrograms/day) may not be adequate therapy for biotin deficiency and might not even be adequate to maintain normal biotin status during TPN.

Low resolution mass spectra of pyrrolidides of isomeric octadecadienoic acids and other polyunsaturated straight chain fatty acids are presented and discussed. The spectra of the pyrrolidides contain mainly ions from the polar part of the molecule and give spectra that are specific for each isomer. The interpretation follows, in most cases, the rule developed for monounsaturated fatty acid pyrrolidides.

Serum was obtained from approximately 10 individuals of each sex from each decade of life from 0 to 90 years of age. Most of the serum samples were obtained from the excess remaining after diagnostic procedures performed for hospitalized patients. The individuals were screened according to tentative diagnosis, and overt cases of diseases known to have effects upon essential fatty acid (EFA) metabolism were eliminated. Serum lipids were separated into phospho- lipids, cholesteryl esters, triglycerides, and free fatty acids. These lipid classes and a sample of the total lipids were subjected to fatty acid analysis by gas chromatography. The data produced were arranged by computer to compare the effects of age upon each fatty acid present and upon each parameter calculated from fatty acid composition for each lipid group and each sex. No significant difference between sexes was found for any individual fatty acid in any lipid, but the average total unsaturation of all lipid classes was significantly higher for males than for females at both 0 and 90 years of age. In cholesteryl esters, and to a lesser extent in phospholipids, the total polyunsaturated fatty acids, the total co6 acids and the sum 18:2e�6 + 20:4w6 - 20:3w9 declined more rapidly with age in females than in males, suggesting a trend toward EFA deficiency, although the ratio 20:3w9/ 20:4�6 did not change significantly. The age and sex differences observed and the SD encountered were much smaller than the changes observed in EFA deficiency, indicating that this population has utility in comparisons with suggested cases of EFA deficiency. The triene/tetraene ratio, 20: 3w9/20:4w6, was found to be 0.1 ± 0.08 for male and female populations, indicating that a ratio above 0.2 should be considered the upper limit of normalcy. Between 0 and 4 months of age, a profound change took place in the patterns of fatty acids in serum lipids. At birth, phosphohipids were low in l8:2c,6 but 20:&,6 and 20:3co9 were elevated. The ratio of 20:3�,9/20:4w6 was 0.16 at birth and decreased progressively during infancy. Some of these observations suggest that at birth the infant has marginal reserves of EFA. The drastic change in composition of serum lipid shortly after birth probably reflects a change in supply of EFA from one rich in 20:4w6 and poor in 18:2�,6 to one high in 18:2�6 and low in 20:4�6. This may have significance in the nutrition of premature or very young infants. Am. J. Clin. Nuir. 32: 2390-2399, 1979.