Mass spectrometry of lipids. I. Cyclopropane fatty acid esters

A method was developed for the almost quantitative conversion of unsaturated esters (from monoenes to tetraenes) to cyclopropanes using diiodomethane and a highly active zinc-copper couple. These derivatives are sufficiently volatile for GLC analysis andcis andtrans isomers can be distinguished by this technique. Equivalent chain lengths of the cyclopropane derivatives were measured on polar and nonpolar phases. The mass spectra of the monocyclopropane compounds are very similar to those of the parent unsaturated esters. Those of dicyclopropanes, however, are quite distinctive so that the original structure of the ester can be deduced. Polycyclopropanes give complex spectra which are difficult to interpret in terms of the position of the original double bonds.

Omega 3 but not omega 6 fatty acids inhibit AP-1 activity and cell transformation in JB6 cells

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.

The slow discovery of the importance of omega 3 essential fatty acids in human health

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.

13-phenyltridecanoic acid in seed lipids of some aroids

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.

Effects of the incubation of long-chain polyunsaturated fatty acids on platelet lipids and thromboxane release

Alterations of dietary lipids have been advocated to manipulate platelet release of thromboxane A2. We studied the effects of incubating platelets with several different polyunsaturated fatty acids on platelet-lipid profile and release of thromboxane A2 in response to platelet stimulation. Porcine platelets were isolated by centrifugation, washed three times in Tyrode's solution, and incubated with fatty acids (500 microM) in Tyrode's solution with albumin. Seven polyunsaturated fatty acids of varying lengths (18-, 20-, and 22-carbon chain) of the omega3 and omega6 families were incubated for 60 min at concentrations of 0, 10, 30, and 100 microM with saturated fatty acids comprising the remainder of the 500 microM fatty acids. The platelets were then stimulated for 5 min with A23187 (30 microM). Indomethacin was added, and the platelets were pelleted. Platelet lipids were extracted in hexane, transesterified and quantified by gas chromatography. Using radioimmunoassay, we measured thromboxane B2, the stable metabolite of thromboxane A2, in the platelets' supernatant. A 1-h incubation in each of the seven polyunsaturated fatty acids had no significant effect on platelet-lipid composition. We found a significant increase in thromboxane B2 production in arachidonic acid (100 microM) incubated platelets (324.0 +/- 63.8% of baseline) that was inhibited by eicosapentaenoic acid (81.0 +/- 26.8%, P < 0.01) and to a lesser extent by dihomogammalinolenic acid (189.8 +/- 28.3%, P < 0.03). We conclude that in altering diets to affect platelet release of thromboxane, the two fatty acids of interest are the 20-carbon chain fatty acids, dihomogammalinolenic acid and eicosapentaenoic acid. The ideal amount of each of these fatty acids to be incorporated entails supraphysiologic but pharmacologically achievable levels of fatty acids in plasma.

Essential fatty acid deficiency and predisposition to lung disease in cystic fibrosis

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.

Isolation and characterization of rat cholangiocyte vesicles enriched in apical or basolateral plasma membrane domains

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)

Patients with anorexia nervosa demonstrate deficiencies of selected essential fatty acids, compensatory changes in nonessential fatty acids and decreased fluidity of plasma lipids

The objective of this study was to assess the essential fatty acid status of patients with anorexia nervosa. Blood was collected from eight fasting female anorexia nervosa patients with a mean of 81% ideal body weight. Fatty acid composition of phospholipids, nonesterified fatty acids, triglycerides and cholesteryl esters of plasma were determined by capillary gas chromatography to indicate polyunsaturated fatty acids status compared with 19 healthy female adults < 25 y old. Subjects with anorexia nervosa showed polyunsaturated fatty acid deficiencies in plasma phospholipids different from simple nutritional essential fatty acid deficiency or chronic malnutrition. The phospholipid profile showed significantly lower (n-6) and (n-3) elongation and desaturation products, and elevated short-chain saturated, short-chain monounsaturated, branched-chain and odd-chain fatty acids. These elevations indicate enhancement of biosynthesis of alternative fatty acids that only partially compensated for the loss of polyunsaturated fatty acids in providing membrane "fluidity." Calculated mean melting point of the fatty acids of phospholipids in patients with anorexia nervosa was elevated 7.7 degrees C above normal values. These results demonstrate that patients with anorexia nervosa have deficiencies of selected essential fatty acids, compensatory changes in nonessential fatty acids and decreased fluidity of plasma lipids.

Human subcutaneous adipose tissue shows site-specific differences in fatty acid composition

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.

Serum fatty acid profiles in cystic fibrosis patients and their parents

Fatty acid compositions of the major serum lipid classes from 43 cystic fibrosis (CF) homozygotes (CF patients), 36 obligate heterozygotes (parents of CF patients) and 34 controls were determined by capillary gas chromatography. Fatty acid compositions of the homozygote CF patients were skewed in the direction of relative essential fatty acid deficiency in comparison with the controls. Less pronounced, but similar deviations from normal, were observed in the heterozygotes. Homozygotes with normal fatty acid compositions and heterozygotes with considerably disturbed fatty acid profiles were found.

Diets rich in lean beef increase arachidonic acid and long-chain omega 3 polyunsaturated fatty acid levels in plasma phospholipids

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)

Essential fatty acid deficiency profiles in idiopathic immunoglobulin A nephropathy

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.

Myocardial lipid composition in turkeys with dilated cardiomyopathy

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 (18:2 omega 6) 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 (18:2 omega 6) 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.

Abnormal plasma lipids of patients with Retinitis pigmentosa

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.

Effects of endotoxin on pigs prefed omega-3 vs. omega-6 fatty acid-enriched diets

We investigated in a porcine model whether omega-3 fatty acids modify the physiological response to sepsis. For 8 days, 16 male pigs were fed a diet containing 18% fat by weight enriched with either omega-3 or omega-6 fatty acids (FA). A group of six pigs receiving their regular diet served as controls. The omega-3 FA-supplemented pigs had elevated levels of omega-3 FA in their serum-free FA, serum phospholipid (PL), and platelet PL levels compared with either of the other groups. On the ninth day, the unanesthetized pigs were injected with 0.3 mg/kg of endotoxin (Escherichia coli) intravenously. The animals had a significant decrease in their arterial O2 pressure (PaO2) [from 84.4 +/- 6.8 (SD) to 64 +/- 9.4, and from 83.1 +/- 7.2 to 55.9 +/- 6.3 mmHg in the omega-6 FA and regular diet groups, respectively]. The PaO2 did not decrease in the omega-3 FA pigs. The omega-3 FA group had significantly lower pulmonary vascular resistance (541 +/- 205 dyn.s.cm-5) 20 min after endotoxin compared with either the omega-6 FA or regular diet groups (797 +/- 233 and 1,102 +/- 552 dyn.s.cm-5, respectively) and more normal blood pressure compared with the other two groups. Plasma thromboxane (Tx) B2 and 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha) levels were lowest in the omega-3 FA diet group and highest in the regular diet group.(ABSTRACT TRUNCATED AT 250 WORDS)

Fatty acid composition of hepatic triglycerides in Reye's syndrome: implications for hepatic desaturase abnormalities

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.

Essential fatty acid status and fluidity of plasma phospholipids in cystic fibrosis infants

The fatty acid (FA) patterns of cord serum phospholipids (PLs) were examined in 4 cystic fibrosis (CF) newborns, 8 non-CF siblings, and 22 normal control subjects. Plasma from 27 newly diagnosed CF infants and 38 normal infants aged less than 2 y were studied for comparison. CF cord-blood PLs had patterns similar to those of CF siblings and to normal newborns, but the pattern for CF did not shift toward adult patterns during infancy as did patterns for normal infants. CF infants at diagnosis exhibited a deficiency pattern in which 18: 2 omega 6, 20:4 omega 6, 22:4 omega 6, an omega 3 polyunsaturated fatty acids (PUFAs) were significantly subnormal and 18:3 omega 6, total saturated fatty acids, and total monounsaturated fatty acids were significantly elevated compared with normal infants. In PLs in CF infants, although mean chain length of FAs was low, mean melting point was elevated 2.4 degrees C and double-bond index was low (both P less than 0.001), implying a significantly lessened fluidity. Nutritional supplements of both omega 6 and omega 3 PUFAs are cated.

Unusual isomeric polyunsaturated fatty acids in liver phospholipids of rats fed hydrogenated oil

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.

Deficiency of essential fatty acids and membrane fluidity during pregnancy and lactation

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.

Improvement in immune function in ICU patients by enteral nutrition supplemented with arginine, RNA, and menhaden oil is independent of nitrogen balance

Hypermetabolism and multiple organ failure syndrome (MOFS) after trauma, surgery, or sepsis is associated with accelerated catabolism, the rapid onset of malnutrition, and immune system failure. Current nutritional support, enteral or parenteral, can achieve an acceptable nutritional response but appears unable to improve immune function. Nutrients such as arginine, refined menhaden oil, and RNA have been found to have immune-stimulating properties. This randomized blind prospective trial compared two nutritionally complete enteral formulas, one supplemented with arginine, menhaden oil, and RNA, on the disease-specific effects of anergy and suppression of in vitro tests of immune function in intensive-care patients and the nutritional outcome of nitrogen balance. After 7-10 days of enteral nutrition in patients with persistent sepsis syndrome, both formulas were associated with the achievement of net nitrogen retention and improved visceral protein status but with nonresolution of anergy. However, the supplemented formula was associated with marked stimulation of in vitro lymphocyte proliferative responses and a significant reduction in 3-methylhistidine excretion. Six and 12-mo follow-up data demonstrated no long-term effects. Nutrients targeted to effect the disease-induced in vitro suppression of immune function in MOFS appear to achieve that end independent of the nutritional outcome of nitrogen balance and without adverse clinical outcome.

Obesity and weight loss alter serum polyunsaturated lipids in humans

Serum omega 6 (n-6) fatty acids were assessed in 12 obese women during an outpatient very-low-calorie diet (VLCD). Ten subjects (S10) achieved a mean weight loss of 17 kg over 3-5 mo (initial weight-for-height 157%). Serum was obtained before (baseline) and monthly during the VLCD and from five of them (S5) after 2-3 mo of weight stability (refed) at 21 kg of loss. At baseline for S10, the serum phospholipid (PL) 20:4 omega 6 was 9.16 wt% and differed from normal (12.81 wt%) by P less than 0.0001, but cholesterol ester (CE) 20:4 omega 6 did not differ from normal. During 3 mo of VLCD, the S10 serum PL and CE 18:2 omega 6 fell (P less than 0.005 and 0.0001, respectively). Serum PL 20:4 omega 6 rose to normal during VLCD months 1-3 (P less than 0.01) while the serum CE 20:4 omega 6 rose above normal (P less than 0.0002). During the VLCD, S5 results paralleled S10. However when refed, S5 PL and CE 18:2 omega 6 and 20:4 omega 6 all reverted to baseline (PL 20:4 omega 6 below normal, P less than 0.001). Serum PL 20:4 omega 6 is low in moderate obesity, corrects to normal during a VLCD, but regresses to the predict abnormality after weight loss.

Effects of a fish oil diet on pigs' cardiopulmonary response to bacteremia

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.

Reduced adipose 18:3 omega 3 with weight loss by very low calorie dieting

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 18:1 omega 9, 18:2 omega 6, and 20:4 omega 6 did not change, but 18:3 omega 3 fell (0.67 to 0.56 wt%, p less than 0.0001) as did 20:5 omega 3 (0.08 to 0.05, p less than 0.01). Adipose tissue 22:6 omega 3 rose from 0.03 to 0.07 (p less than 0.01). In Group 2, only 18:3 omega 3 showed a change, falling from 0.71 to 0.69 to 0.59 wt% across weight loss (p = 0.03 by analysis of variance). We conclude that the major fatty acids are oxidized in proportion to their composition in adipose triglyceride.(ABSTRACT TRUNCATED AT 250 WORDS)

Alteration of the cellular fatty acid profile and the production of eicosanoids in human monocytes by gamma-linolenic acid

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.

Influence of hyperalimentation on rat hepatic microsomal fluidity and function

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.

Collisional activation of a series of homoconjugated octadecadienoic acids with fast atom bombardment and tandem mass spectrometry

High-energy collisional activation (CA) of long-chain fatty acid ions induces decompositions that occur remote from the charge site. These charge-remote fragmentations (CRFs) have been shown to provide much structural information. In this report, the CRF of a continuous series of 12 homoconjugated octadecadienoic acids was studied with fast atom bombardment and tandem mass spectrometry. Each fatty acid was desorbed as the carboxylate anion, [M - H](-), the dilithiated species, [M - H+2Li](+), or the bariated species, [M - H+Ba](+), giving three ways of localizing the charge. A characteristic pattern is generated for CRF of the 1,4-diene functional group, and this allows for the rapid identification of the functional group and its location on the chain. Minor variations of this pattern are observed for the different ionic precursors and for different locations of the double bonds. Furthermore, there are a few complications from different types of charge-proximate reactions, especially of the fatty acid carboxylates.

Reduced arachidonate in serum phospholipids and cholesteryl esters associated with vegetarian diets in humans

Lipid fractions such as phospholipids (PLs), cholesteryl esters (CEs), and free fatty acids (FFAs) represent source pools for eicosanoid synthesis. To determine whether dietary habits affect the enrichment of 20:4n-6 in these precursor pools, we studied humans with partial or complete arachidonate restriction resulting from chronic avoidance of animal fat and tissue. Fasting serum was obtained from omnivorous control subjects (Omni, n = 100), semivegetarians (Semiveg, n = 16), and vegetarians (Veg, n = 25). PLs, CEs, FFAs, and triglyceride (TG) fatty acids were quantitated by thin-layer and gas chromatography. Serum 20:4n-6 was lower in the PL fraction in both Veg (p less than 0.01) and Semiveg groups (p less than 0.05) than in the Omni group and lower in the CE fraction in the Veg group (p less than 0.05). Serum 18:2n-6 did not differ between groups for any serum lipid fraction. 18:3n-3 was elevated in PLs and CEs of both Veg (p less than 0.05 and 0.01) and Semiveg groups (p less than 0.05 and 0.01) compared with the Omni group but did not result in differences in 20:5n-3 in PLs or CEs between diet groups. The lower concentration of 20:4n-6 in serum PLs and CEs of the Veg group indicates that dietary arachidonic acid enriches its circulating pool in humans; however, 20:5n-3 is not similarly responsive to dietary restriction.

Deficiencies of polyunsaturated fatty acids and replacement by nonessential fatty acids in plasma lipids in multiple sclerosis

Fatty acid compositions of plasma phospholipids, cholesteryl esters, triacylglycerols, and nonesterified fatty acids of 14 clinically proven and graded cases of multiple sclerosis were determined by capillary gas chromatography and compared with the values obtained for 100 normal, healthy subjects. In phospholipids, linoleic acid (18:2 omega 6; 18 carbon atoms, 2 double bonds, 6 carbon atoms beyond last double bond) was normal and 18:3 omega 6 was increased, but all subsequent omega 6 acids were subnormal (P less than 0.001), indicating impairment of chain elongation. All omega 3 acids were subnormal. The paucity of polyunsaturated fatty acids was compensated mass-wise by an increase in saturated acids. Disproportionate increases in short-chain, saturated, and monounsaturated acids, decreases in long-chain homologs, and increases of branched and odd-chain acids were observed. Loss of polyunsaturated fatty acids and replacement by nonessential acids lowered mean chain length and raised mean melting point significantly, suggesting that lowered membrane fluidity was only partially compensated by endogenous synthesis of lower-melting, nonessential acids. This phenomenon was not observed in cholesteryl esters or triacylglycerols. Nonesterified fatty acids showed significant changes in pattern of possible autacoid precursors. The abnormal profile of fatty acids in multiple sclerosis has features in common with profiles of other syndromes involving viral infections.

Modulation of Kupffer cell membrane phospholipid function by n-3 polyunsaturated fatty acids

Dietary n-3 polyunsaturated fatty acids (PUFAs) have been reported to improve clinical outcome in a number of inflammatory diseases including burns and sepsis. One mechanism contributing to the anti-inflammatory effect is the incorporation of n-3 PUFAs into membrane phospholipids which decreases macrophage eicosanoid production. We hypothesize that an additional mechanism for their effects is an alteration of membrane signal transduction that decreases macrophage responsiveness to inflammatory stimuli. Kupffer cells, the fixed macrophages of the liver, were obtained from rats pair fed diets for 6 weeks with 15% of calories supplied as menhaden (high n-3), corn (control), or safflower (high n-6) oils. The effects of the dietary oils on Kupffer cell membrane signal transduction and eicosanoid production were assessed by measuring inositol phospholipid (PI) metabolism, intracellular calcium responses, and prostaglandin E2 (PGE2) production to the inflammatory signals endotoxin (LPS) and platelet activating factor (PAF). The menhaden oil diet resulted in significant incorporation of n-3 PUFAs into total cellular PUFAs compared to corn and safflower oil. (total n-3 PUFAs, 28.1% menhaden vs 2.1% corn vs 1.2% safflower, P less than 0.03). This incorporation altered signal transduction of PAF as both PI turnover (65% +/- 10% of corn oil) and calcium response (0.6-fold vs 5.0-fold for corn oil) were significantly reduced in the menhaden oil group. (P less than 0.05) The menhaden oil diet also reduced significantly PGE2 production in response to PAF and LPS (corn, 348 +/- 23 pg/ml; menhaden, 48 +/- 6 pg/ml, P less than 0.01). We conclude that, in addition to modulating eicosanoid production, n-3 PUFAs can also alter macrophage membrane signal transduction.(ABSTRACT TRUNCATED AT 250 WORDS)

Modulation of hepatic ferrochelatase activity by dietary manipulation of mitochondrial phospholipid fatty acyl groups

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 acyl groups. 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 oil-fed 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.

Fatty acid pattern of tissue phospholipids in copper and iron deficiencies

Because copper and iron have been reported to be essential cofactors in delta 9 desaturation of fatty acids, the effects of different dietary intakes of copper and iron on tissue fatty acids were studied. Male Long-Evans rats (ten per group) were fed diets containing adequate, deficient or excess copper or iron. On day 42 of the dietary regimen, the animals were killed and tissues and blood were removed for analysis of metals and fatty acids of phospholipids. Compared with the copper-adequate rats, the copper-deficient rats showed increased 18:0 in liver and decreased 16:1 omega 7 in liver, heart and serum. There were no differences for 16:0 or 18:1 omega 9. Intake of excess copper did not cause an increase in products of delta 9 desaturation. Comparisons between iron-deficient and iron-adequate rats showed that iron deficiency increased 18:2 omega 6 in liver and serum and decreased 20:4 omega 6 in serum only. Relative percentages of 16:0, 18:0, 16:1 omega 7 and 18:1 omega 9 in liver and serum phospholipids were similar for both groups. Intake of excess iron caused a decrease in 18:2 omega 6; and 16:0 and 18:1 omega 9 were higher in the liver of the iron-excess group than the iron-deficient group. This study did not support the requirement for copper or iron in the delta 9 desaturation of fatty acids as expressed in phospholipids of liver, heart and serum.

Effects of biotin deficiency on plasma and tissue fatty acid composition: evidence for abnormalities in rats

Abnormalities of fatty acid composition have been detected in the plasma of patients who developed frank biotin deficiency during parenteral nutrition. We sought to determine which abnormalities of fatty acid composition, if any, would be replicated in the biotin-deficient rat and to determine the relative temporal relationships of these abnormalities to biotin nutritional status. We measured fatty acid compositions of the phospholipids extracted from plasma, heart, and liver and assessed biotin nutritional status longitudinally in biotin-deficient and biotin-treated rats during progressive biotin deficiency. In the biotin-deficient group, significant increases relative to the biotin-treated group were detected in all three tissues in the odd-chain fatty acids 15:0 and 17:0. In the biotin-deficient rats, significant increases in 18:2 omega 6 in liver and 18:3 omega 6 in plasma and liver and significant decreases in 22:5 omega 6 were detected in plasma and liver. The constellation of fatty acid abnormalities observed in the biotin-deficient rats was not identical to that observed in biotin-deficient patients, but abnormalities in composition of odd-chain fatty acids were detected in both human and rat and therefore are attributable to biotin deficiency per se. The abnormalities in fatty acid composition were already present by wk 4 on the egg white diet; the cutaneous findings appeared between wk 3 and 6. These observations are consistent with the hypothesis that an abnormality in fatty acid metabolism may play a pathogenetic role in the cutaneous manifestations of biotin deficiency.

Fatty acid intake and Kupffer cell function: fish oil alters eicosanoid and monokine production to endotoxin stimulation

Diets high in n-3 fatty acids appear to have an anti-inflammatory effect, which is thought to be due to decreased macrophage prostaglandin (PG) and thromboxane (Tx) production after incorporation of these fatty acids into cell membrane phospholipids. The effect of n-3 fatty acids incorporation on macrophage monokine release in response to septic stimuli is not well established. Kupffer cells, the fixed macrophages of the liver, were obtained from rats fed diets with fat sources derived from corn oil (CO, control), fish oil (FO, high in n-3 fatty acids), or safflower oil (SO, high in n-6 fatty acids) for 2 or 6 weeks. After exposure to bacterial lipopolysaccharide, Kupffer cells from rats fed FO for 2 or 6 weeks produced less PG and Tx than Kupffer cells from rats fed CO or SO. After 2 weeks of defined diets, interleukin-1 (IL-1) and tumor necrosis factor release were not affected by dietary fat source. In contrast, after 6 weeks of feeding, Kupffer cells from both the FO and the SO groups released less IL-1 and tumor necrosis factor when triggered by lipopolysaccharide than Kupffer's cells from animals fed the control diet that contained CO. These data suggest that altered monokine release from macrophages may contribute to the anti-inflammatory effect of diets high in n-3 fatty acids. Also shown in our results is that prolonged changes in membrane phospholipid content induced by dietary fat source can influence not only PG and Tx production but monokine release as well.

Polyunsaturated fatty acids of serum lipids in myocardial infarction

Two groups of volunteers had blood drawn for serum analysis of fatty acids. The first group was comprised of patients admitted to the hospital with possible myocardial infarction (MI). Blood was drawn at admission and at 12, 24 and 48 hr. These patients were subsequently divided into three groups, those with MI, those without (No MI) and those taking prostaglandin inhibitors (PGI), on the basis of the cardiac enzymes, electrocardiograms and clinical history. A fourth group of Normal nonstressed people was also drawn at 0, 12, 24 and 48 hr for comparison. Fatty acid composition of phospholipids (PL), nonesterified fatty acids (NEFA), triglycerides (TG) and cholesteryl esters (CE) was determined by capillary gas chromatography (GC), and comparisons were made between the MI, No MI, PGI and Normal groups. Total NEFA were significantly elevated in patients admitted for possible MI compared with Normals. Those patients with MI had marginally higher levels of NEFA than the No MI group at each sampling time, but this difference was not statistically significant. The MI, No MI and PGI groups had significantly different fatty acid patterns in NEFA with reduced percentages of arachidonic acid (AA) than controls. The fatty acid patterns in the four lipid classes showed few significant differences comparing the MI, No MI and PGI groups. The regular use of prostaglandin inhibitors before hospitalization for chest pain was associated with a reduced frequency of MI (p less than 0.002). NEFA levels, nonesterified AA levels and fatty acid patterns in this group did not differ from those patients not taking prostaglandin inhibitors.