Triacylglycerol-rich lipoproteins derived from healthy donors fed different olive oils modulate cytokine secretion and cyclooxygenase-2 expression in macrophages: the potential role of oleanolic acid

PURPOSE

Current evidence suggests that consumption of virgin olive oil (VOO) helps to protect against the development of atherosclerosis and that minor components such as oleanolic acid contribute to this effect. In this study, the effects of triacylglycerol-rich lipoproteins (TRLs) derived from olive oil on inflammatory processes in macrophages and how they are modulated by oleanolic acid was investigated.

METHODS

TRLs isolated from healthy volunteers 2 and 4 h after a test meal containing VOO, pomace olive oil (POO) (the second pressing of olive oil, enriched in minor components) or POO enriched with oleanolic acid (OPOO) were incubated with macrophages derived from the human monocyte cell line, THP-1.

RESULTS

All types of TRLs caused a decrease of about 50% in the secretion of monocyte chemoattractant protein-1 (MCP-1) by the cells. Interleukin (IL)-6 secretion was also significantly decreased by 2 and 4 h VOO TRLs and by 4 h OPOO TRLs. In contrast, increased IL-1β secretion was observed with all 2 h TRL types, and increased tumour necrosis factor-α (TNF-α) production with 2 h VOO and POO, but not OPOO, TRLs. TRLs isolated after 4 h, however, had no significant effects on TNF-α secretion and increased IL-1β secretion only when they were derived from VOO. Cyclooxygenase-2 (COX-2) mRNA expression was strongly down-regulated by all types of TRLs, but protein expression was significantly depressed only by 4 h OPOO TRLs.

CONCLUSION

These findings demonstrate that TRLs derived from olive oil influence inflammatory processes in macrophages and suggest that oleanolic acid may have beneficial effects.

Influence of minor components of olive oils on the composition and size of TRLs and on macrophage receptors involved in foam cell formation

Metabolic and epidemiologic studies support the idea that the type of dietary fat is more important than the total amount of fat with respect to the development of atherosclerosis and the risk of cardiovascular heart disease. Dietary fat is carried in CMs (chylomicrons), which can be taken up by macrophages without need of further oxidation, leading to the formation of foam cells and initiating or aggravating the atherogenic process. Evidence from different studies has shown that dietary fat can influence the composition and size of TRLs (triacylglycerol-rich lipoproteins), which might modulate their atherogenicity to a certain extent. In particular, experiments in vitro have shown the anti-atherogenic effects of minor components from olive oil when forming part of TRL, as these particles give minor lipid components the opportunity to interact with the cells implicated in endothelial dysfunction and atherogenesis. However, the exact mechanisms mediating CM uptake by macrophages still remain unclear. Thus further studies are needed to understand how the modifications of TRL composition caused by dietary fats could modulate the expression of macrophage receptors and foam cell formation, or even improve the atherogenic risk of these particles.

Modulation of the effects of chylomicron remnants on endothelial function by minor dietary lipid components

There is emerging evidence that minor components from dietary oils can modulate or even improve events occurring in the development of atherosclerosis. One of the earliest events of the atherosclerotic process is endothelial dysfunction, which is an activation of the endothelium manifested by an increase in pro-inflammatory molecules, such as cytokines and adhesion molecules. Chylomicron remnants, such as LDL (low-density lipoprotein), are considered to be pro-atherogenic lipoproteins because they interact with endothelial cells and macrophages, increasing endothelial dysfunction mainly by the disturbance of the redox state in the cell. However, chylomicrons are, at the same time, the natural carriers of dietary lipids in plasma, which gives minor lipid components the opportunity to interact with the cells implicated in endothelial dysfunction and atherogenesis. Some of these components are known to exhibit antioxidant, anti-inflammatory and anti-atherogenic effects in vitro, even forming part of triacylglycerol-rich lipoproteins, such as chylomicrons.

International conference on the healthy effect of virgin olive oil

1. Ageing represents a great concern in developed countries because the number of people involved and the pathologies related with it, like atherosclerosis, morbus Parkinson, Alzheimer's disease, vascular dementia, cognitive decline, diabetes and cancer. 2. Epidemiological studies suggest that a Mediterranean diet (which is rich in virgin olive oil) decreases the risk of cardiovascular disease. 3. The Mediterranean diet, rich in virgin olive oil, improves the major risk factors for cardiovascular disease, such as the lipoprotein profile, blood pressure, glucose metabolism and antithrombotic profile. Endothelial function, inflammation and oxidative stress are also positively modulated. Some of these effects are attributed to minor components of virgin olive oil. Therefore, the definition of the Mediterranean diet should include virgin olive oil. 4. Different observational studies conducted in humans have shown that the intake of monounsaturated fat may be protective against age-related cognitive decline and Alzheimer's disease. 5. Microconstituents from virgin olive oil are bioavailable in humans and have shown antioxidant properties and capacity to improve endothelial function. Furthermore they are also able to modify the haemostasis, showing antithrombotic properties. 6. In countries where the populations fulfilled a typical Mediterranean diet, such as Spain, Greece and Italy, where virgin olive oil is the principal source of fat, cancer incidence rates are lower than in northern European countries. 7. The protective effect of virgin olive oil can be most important in the first decades of life, which suggests that the dietetic benefit of virgin olive oil intake should be initiated before puberty, and maintained through life. 8. The more recent studies consistently support that the Mediterranean diet, based in virgin olive oil, is compatible with a healthier ageing and increased longevity. However, despite the significant advances of the recent years, the final proof about the specific mechanisms and contributing role of the different components of virgin olive oil to its beneficial effects requires further investigations.

Changes in fatty acid composition of rat liver and serum induced by distal small bowel resection

The serum lipid composition and the fatty-acid profiles of the major lipid fraction (triglycerides, esterified cholesterol, and phospholipid) of liver and serum were examined 6 weeks after both 50% and 75% distal small bowel resection (DSBR). Total serum lipid content did not modify after DSBR. Esterified cholesterol and phospholipid levels of the serum did not significantly change after the operation. However, a significant increase in both free cholesterol and triglyceride levels was observed after DSBR. Different fatty acid changes in the liver and serum lipid fractions were found after DSBR, with the greatest differences in the hepatic esterified cholesterol fraction. These results suggest that DSBR affects both the lipid composition and the fatty acid composition of major lipid fraction of liver and serum.

Dietary virgin olive oil triacylglycerols as an independent determinant of very low-density lipoprotein composition

OBJECTIVE

We examined the effects of virgin olive oil (VOO) triacylglycerols (TGs) on the lipid composition of human very low-density lipoprotein (VLDL).

METHODS

Twenty-one normocholesterolemic, normotensive, non-diabetic elderly subjects were recruited for the study. Two VOOs (VOO1 and VOO2) of the same variety, with an equivalent composition in minor components and differing only in the oleic and linoleic acid concentrations, were administered for 4 wk each to assess the effect of their TG molecular species compositions. Blood was collected after an overnight fast, VLDLs were isolated by ultracentrifugation, and lipid classes, TG molecular species, and TG fatty acid composition were determined.

RESULTS

Dietary VOOs significantly differed in TG molecular species composition. VOO1 represented larger amounts of triolein (P < 0.01), whereas VOO2 was significantly enriched with dilinoleoyl-oleoyl-glycerol, linoleoyl-dioleoyl-glycerol, and linoleoyl-oleoyl-palmitoyl-glycerol (P < 0.01). For VLDL, intake of VOO1 caused an increase of total TG (P < 0.01) due mainly to increases in triolein and linoleoyl-dioleoyl-glycerol. Conversely, VOO2 increased VLDL cholesteryl esters (P < 0.01) and TG rich in arachidonic acid (P < 0.01).

CONCLUSIONS

The different TG molecular species compositions of dietary oils may be an independent determinant of the lipid composition of VLDL in elderly people and therefore may play a role in regulating lipoprotein metabolism in these subjects.

Sphingosine 1-phosphate signal survival and mitogenesis are mediated by lipid-stereospecific binding of triacylglycerol-rich lipoproteins

Proof for the role of triacylglycerol-rich lipoproteins (TRLs) in the development of cardiovascular events is accumulating. We recently reported that postprandial TRLs bind to and internalize into human aortic vascular smooth muscle cells (HA-VSMCs) by a lipid-dependent mechanism. We now show that postprandial TRLs triggered hydrolysis of sphingomyelin and stimulation of the sphingosine kinase producing sphingosine 1-phosphate (S1P). In addition, postprandial TRLs exhibited survival and mitogenic effects. Interestingly, the signals were modulated by the nature of the fatty acids located at the sn-2 position in the triacylglycerol molecules of TRL. This lipid-stereospecific regulation of S1P cellular levels in HA-VSMCs provides a novel insight into the intrinsic role of dietary fatty acids and the mechanism mediated by triacylglycerol-containing postprandial lipoproteins in the pathogenesis of atherosclerosis.

Incorporation of dietary triacylglycerols from olive oil and high-oleic sunflower oil into VLDL triacylglycerols of hypertensive patients

OBJECTIVES

To establish whether the ingestion of diets enriched with olive oil or high-oleic sunflower oil may produce changes in the composition of VLDL triacylglycerols from hypertensive patients. It could be relevant for the uptake and metabolism of triacylglycerol-derived metabolites by extrahepatic tissues.

DESIGN

Patients were assigned to the diets in a random-order sequence.

SUBJECTS

The participants were 24 hypertensive patients recruited from a religious community.

INTERVENTIONS

The study was conducted over two four week periods with a four week washout period between both MUFA diets.

RESULTS

Dietary olive oil kept in balance the content of saturated fatty acids and decreased the content of arachidonic acid in VLDL triacylglycerols. HOSO diet reduced the content of palmitic acid and increased the content of linoleic acid. There was also a decrease in trioleate-glycerol and an increase in tripalmitate-glycerol of VLDL after the MUFA diets, but these effects were more pronounced in the HOSO group. Intake of olive oil decreased the content of disaturated triacylglycerols and increased the content of dioleate-containing triacylglycerols. A decrease in palmitate-dioleate-glycerol after dietary HOSO was observed. Olive oil (but not HOSO) promoted the presence of long-chain PUFA of n-3 family at the sn-2 position of VLDL triacylglycerols.

CONCLUSIONS

Our data indicate that olive oil and HOSO, providing a similar concentration of MUFA (oleic acid), differ in the formation of VLDL triacylglycerols in hypertensive patients.

Sodium transport kinetics, cell membrane lipid composition, neural conduction and metabolic control in type 1 diabetic patients. Changes after a low-dose n-3 fatty acid dietary intervention

BACKGROUND

A decreased content of n-3 fatty acids in erythrocyte membrane of type 1 diabetic patients, which is inversely related to plasma levels of HbA(1c), has been reported previously. Our aim in this study was to observe the changes after a low-dose n-3 fatty acid (330 mg/day docosahexaenoic acid and 630 mg/day eicosapentanoic acid) dietary intervention in the lipid composition of cell membrane and metabolic control (measured according to plasma HbA(1c) levels). Since changes in both parameters may alter transmembrane sodium transport or influence parameters measuring target organ damage, we also studied the neural conduction quality and activity of four sodium transporters.

METHODS

Eighteen type 1 diabetic patients were randomly assigned to continue their usual diet (control group) or to supplement their diet with a daily low dose of n-3 fatty acids (supplemented group). The changes between baseline and end values of the following parameters were compared: HbA(1c), lipid and phospholipid composition of cell membrane, activity of four ion carriers and neural conduction quality.

RESULTS

The dietary supplementation caused statistically significant changes in membrane lipid composition, particularly an increase of C22:6 (n-3) and the total n-3 fatty acid (respectively +0.90+/-1.14% vs. -0.44+/-1.23% and +1.36+/-1.62% vs. -0.5+/-1.80%, p<0.05). After the dietary supplementation, we also observed a significant decrease of HbA(1c) (-2.00+/-1.9% vs. -0.13+/-0.48%, p<0.05), without significant changes in the dose of insulin required, an increase in the motor conduction velocity by the median nerve (+2.12 +/-1.35 m/s vs. -0.8+/-2.34 m/s, p<0.05) and a decrease of the V(max) of the Na(+)-Li(+) countertransport (-96.6+/-111.2 vs. +58.1+/-81.3 micromol/l cell/h(-1), p<0.01).

CONCLUSION

A low-dose omega-3 fatty acid dietary supplementation may change the fatty acid composition of the cell membrane and improve the metabolic control of diabetes. Using this dose, we also observed a decrease of the maximal rate of Na(+)-Li(+) countertransport and a slight improvement of neural conduction.

Folate transport by prawn hepatopancreas brush-border membrane vesicles

The transport system of folic acid (Pte-Glu) by brush-border membrane vesicles (BBMV) isolated from prawn (Penaeus japonicus) hepatopancreas, was studied by measuring the uptake of Pte-Glu. This uptake was found to have two components, intravesicular transport and membrane binding. Membrane binding was not affected by the presence of a transmembrane pH-gradient at a short incubation period. However, a transmembrane pH-gradient increased membrane binding at 60 min. The transport of Pte-Glu appeared to be carrier-mediated, was stimulated by an inwardly proton gradient (pH 5.5 outside, 7.4 inside) and was unaffected by a sodium-gradient. The relationship between pH gradient-driven Pte-Glu uptake and medium Pte-Glu concentration followed saturating Michaelis-Menten kinetics. Eadie-Hofstee representation of the pH gradient-driven Pte-Glu uptake indicated a single transport system with a Km of 0.37 microM and Vmax of 1.06 pmol/mg protein/15 s. These findings indicate that BBMV isolated from prawn hepatopancreas possesses a Pte-Glu transport system similar to that described in mammalian intestine.

Increased Na(+)-H+ exchanger activity in the ileal brush-border membrane of spontaneously hypertensive rats

In the present study, we have examined the intestinal Na+ transport, through the Na+)-H+ exchanger in ileal brush-border membrane vesicles (BBMV) isolated from spontaneously hypertensive rats (SHR), and normotensive Wistar Kyoto (WKY) rats as a control group. Na+ uptake into ileal BBMV was stimulated the presence of a proton gradient (pH 5.5 inside/pH 7.5 outside) in SHR and WKY rats, resulting in a transient accumulation (overshoot) in both groups of rats. No overshoot was observed in the absence of a pH gradient. The magnitude of the accumulation was significantly higher in SHR than in WKY rats. Uptake of Na+ at equilibrium was identical in the presence and the absence of a proton gradient and was not changed in SHR. The use of amiloride inhibited pH gradient-driven Na+ uptake in a dose-dependent manner with a Ki of 90 microM and 100 microM for SHR and WKY rats, respectively. The relationship between proton gradient-driven Na+ uptake and external Na+ concentration was saturable and conformed to Michaelis-Menten kinetics in both SHR and WKY rats. Lineweaver-Burk analysis of the pH gradient-driven Na+ uptake indicated values of Vmax that were significantly increased in SHR compared to WKY rats (11.4 +/- 0.55 nmol/mg/8 s vs. 4.96 +/- 0.78 nmol/mg/8 s for SHR and WKY rats, respectively). In contrast, similar K(m) for Na+ were found between SHR and WKY rats (4.0 +/- 0.2 mM vs. 4.9 +/- 0.6 mM for SHR and WKY rats, respectively). These studies show derangement in ileal BBMV Na+ transport of SHR, which is characterized by increased Na(+)-H+ exchanger activity.

Phospholipid profile and fatty acid composition of rat cecal mucosa in relation to intestinal resection

In this study we examined the effect of distal small bowel resection (DSBR) on the phospholipid composition of rat cecal mucosa. Three groups of animals were used: sham-operated, and 50% and 75% DSBR. The fatty acid composition of phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylinositol (PI), lysophosphatidylcholine (LPC) and sphingomyelin (SM) was also determined. PE was the predominant phospholipid, together with PC, in the 3 groups of animals. Both phospholipids accounted for more than 60% of the total phospholipids. DSBR affected the phospholipid profile of the cecal mucosa. Thus the ratio PC/PE was increased in the 75% resected animals. A decrease in the proportion of LPC and LPE was observed after DSBR, and the PI proportion was not changed in the resected rats. The phospholipid/cholesterol molar ratio was not modified as a consequence of DSBR. Different fatty acid composition changes in the cecal phospholipid subclasses were observed after DSBR. The PC fraction contained the highest amounts of saturated fatty acids in all the animal groups. Linoleic and arachidonic acids were found in all phospholipid fractions in the 3 groups of animals except in the SM of sham rats and in the LPC of resected rats, in which values of arachidonic acid were not found. All these changes might be involved in physicochemical, biochemical and/or functional adaptations observed in the cecum after DSBR.

Intestinal resection and ursodeoxycholic acid: effect on hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase and acyl-CoA:cholesterol acyltransferase activities in the rat

The effect of distal small bowel resection (DSBR) and/or ursodeoxycholic-acid (UDCA) ingestion on hepatic activities of 3-hydroxy-3-methylglutaryl Coenzyme A (HMG-CoA) reductase and acyl-CoA:cholesterol acyltransferase (ACAT) was studied in rats. The total activity and the activity state of the enzyme HMG-CoA reductase were also determined. DSBR significantly increased the total activity of HMG-CoA reductase. This increase was enhanced when rats were treated with UDCA. The active form of the enzyme was increased by DSBR. However, the ingestion of UDCA did not modify these results. Therefore, the observed increase in the total activity of HMG-CoA reductase in resected-rats after the administration of UDCA was due to an increase in the inactive form of the enzyme. The activity of ACAT was decreased in resected animals. This decrease was greater after the treatment of UDCA in resected rats when compared with the corresponding group of untreated rats with UDCA. We conclude that UDCA ingestion increases the effect of intestinal resection on hepatic HMG-CoA reductase and ACAT activities.

Lipid composition and fluidity in the jejunal brush-border membrane of spontaneously hypertensive rats. Effects on activities of membrane-bound proteins

The lipid composition and fluidity of jejunal brush-border membrane vesicles (BBMV) have been studied in spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto (WKY) rats. The activities of both Na(+)-dependent D-glucose cotransport and Na(+)-H+ antiport have also been determined. A significant increase in the level of free cholesterol was observed in jejunal BBMV from SHR compared to WKY rats. Since phospholipid values did not change in either group of animals, a significant enhancement in the free cholesterol/phospholipid ratio was observed in SHR. A decrease in the levels of phosphatidylethanolamine together with an increase in the values of phosphatidylserine was observed in hypertensive rats. Although the content of phosphatidylcholine (PC) and sphingomyelin (SM) was not significantly altered in SHR, the ratio PC/SM significantly increased in these animals when compared to WKY rats. The major fatty acids present in bursh-border membranes prepared from SHR and WKY rats were palmitic (16:0), stearic (18:0), oleic (18:1, n-9) and linoleic (18:2, n-6), and the fatty acid composition was not modified by the hypertension. A decreased fluorescence polarization, i.e., increased membrane fluidity, was observed in SHR, which was not correlated to the increased ratio of cholesterol/phospholipid found in the brush-border membrane isolated from these animals. These structural changes found in SHR were associated to an enhancement in both Na(+)-dependent D-glucose transport and Na(+)-H+ antiport activity in the jejunal BBMV of SHR.

Increased sodium-dependent D-glucose transport in the jejunal brush-border membrane of spontaneously hypertensive rat

The current studies explore the effect of hypertension on D-glucose transport into jejunal brush-border membrane vesicles (BBMV). Spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats, as a control group, were used. The purity of the BBMV from both groups of animals was validated by the finding that the specific activity of brush-border enzyme marker, sucrase, was severalfold greater in membrane vesicles compared with corresponding values in mucosal homogenate. D-glucose uptake was Na+ dependent in both groups of animals, with a transient increase in the intravesicular concentration of D-glucose. However, the initial rate and the magnitude of the accumulation of Na+-dependent D-glucose was significantly higher in SHR compared with WKY rats. In order to investigate the mechanism(s) for the increase in Na+-dependent D-glucose transport in SHR, several experiments were performed: (1) an experiment that indicated 22Na uptake, as an indicator for Na+ permeability, was similar between SHR and WKY rats, (2) kinetic studies that indicated that Vmax values of SHR were significantly greater that those of WKY rats. In contrast, similar Km values for glucose were found between SHR and WKY rats, (3) Na+-dependent phlorizin binding measurements that were not altered by hypertension and (4) a study of the brush-border membrane lipid composition that showed a significant increase in the free cholesterol/phospholipid ratio in SHR. We conclude that altered membrane cholesterol content and consequently altered lipid fluidity could be, at least in part, responsible for the observed increase in Na+-dependent D-glucose transport in SHR.

Lipoprotein concentrations in normolipidemic males consuming oleic acid-rich diets from two different sources: olive oil and oleic acid-rich sunflower oil

The effects on plasma lipid concentrations of two oleic acid-rich diets, prepared with two different plant oils--olive oil and sunflower oil high in monounsaturated fatty acids (MUFAs)-- were compared with a National Cholesterol Education Program (NCEP) I diet. Twenty-one healthy, normolipidemic, young males consumed an NCEP-I diet (30% of energy as fat) during a 25-d period. Subjects were then assigned to two 4-wk study periods, according to a randomized, crossover design. Group one was placed on an olive oil-enriched diet (40% fat, 22% MUFAs), followed by a 4-wk period of a sunflower oil-enriched diet (40% fat, 22% MUFAs). In group two, the order of the diets was reversed. Both MUFA dietary periods resulted in an increase in high-density-lipoprotein (HDL) cholesterol (7% for the olive oil diet and 4% for the sunflower oil diet) and in apolipoprotein (apo) A-I (9% for both) compared with the NCEP-I diet. Low-density-lipoprotein (LDL) cholesterol and apo B concentrations (x +/- SEM) were lower (P < 0.05) during the sunflower oil diet (2.40 +/- 0.11 mmol/L, 0.85 +/- 0.04 mg/L) than during the olive oil diet (2.64 +/- 0.15 mmol/L, 0.93 +/- 0.05 mg/L). No significant differences were observed in these variables between the sunflower oil and NCEP-I (2.48 +/- 0.13 mmol/L, 0.89 +/- 0.04 mg/L) diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Phospholipid fatty acid composition of hepatopancreatic brush-border membrane vesicles from the prawn Penaeus japonicus

Brush-border membrane vesicles (BBMV) were isolated from prawn hepatopancreas as we previously described (Muriana et al (1993) J Biochem 113, 625-629). The characterization of hepatopancreatic BBMV (hBBMV) by monitoring the activity of marker enzymes indicated a relatively pure apical membrane preparation reduced in basolateral contamination. Phospholipid composition of hBBMV was examined by the Iatroscan TLC/FID technique, whereas the fatty acid profile of phospholipids was examined by capillary gas chromatography. Phosphatidylcholine and phosphatidylethanolamine are the principal phospholipids of these membranes. The major fatty acids of phospholipids are palmitic (16:0), palmitoleic (16:1n-7), stearic (18:0), oleic (18:1n-9), eicosapentaenoic (20:5n-3) and docosapentaenoic (22:5n-3) acids. Individual phospholipids are characterized by distinct fatty acid compositions, but display a similar ratio of unsaturated-to-saturated fatty acids and a similar unsaturation index.

Effect of intestinal resection on phospholipid class distribution and fatty acid composition of mucosal cells in the rat large intestine

In this study we examined the effect of 50% distal small bowel resection (DSBR) on the lipid composition of rat colonic mucosa, including the fatty acid composition of major phospholipid classes, phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylinositol (PI), lysophosphatidylcholine (LPC), and sphingomyelin (SM). Phospholipid, free cholesterol, triacylglycerols, diacylglycerols, and cholesterol ester levels were not affected by the surgical operation. PE together with PC accounted for more than 60% of total phospholipid, in both groups of animals. The relative percentages of PE, PC, PI, SM, and cardiolipin (CL) remained unaffected by DSBR. However, a decrease in the content of LPC was observed in 50%-resected animals. Different fatty acid composition changes in the colonic phospholipid classes were observed after resection. PC fraction contained the highest amounts of saturated fatty acids, but monounsaturated fatty acids were present in high levels in PI fraction, in both groups of animals. DSBR produces different changes in the levels of linoleic and arachidonic acids. These results suggest that the lipid composition and the fatty acid profile of the different phospholipid fractions change in the adaptive response of colon to intestinal resection.

Phospholipid fatty acid compositions of hepatopancreas and muscle from the prawn, Penaeus japonicus

The hepatopancreas and muscle of the prawn, Penaeus japonicus, were analyzed as to the phospholipid fatty acid composition. The most important lipids in the hepatopancreas are triglycerides and phospholipids, while the lipids in muscle are principally phospholipids and free cholesterol. Fatty acids such as palmitic (16:0), stearic (18:0), oleic (18:1 n-9), eicosapentaenoic (20:5 n-3), and docosahexaenoic (22:6 n-3) were prominent in the total phospholipid fatty acid composition. However, phosphatidylethanolamine appeared to be particularly rich in n-3 polyunsaturated fatty acids, sphingomyelin in saturated fatty acids (mainly 18:0), and phosphatidylinositol in monounsaturated fatty acids (mainly 18:1 n-9). Our data indicated that each phospholipid class is characterized by a specific paraffin chain composition.

Cell membrane fatty acid composition in type 1 (insulin-dependent) diabetic patients: relationship with sodium transport abnormalities and metabolic control

We have studied the fatty acid composition of erythrocyte membrane phospholipids in nine Type 1 (insulin-dependent) diabetic patients and nine healthy control subjects. Cell membranes from the diabetic patients showed a marked decrease in the total amount of polyunsaturated fatty acids (19.0% +/- 2.2 vs 24.6% +/- 1.4, p < 0.0001) mainly at the expense of docosahexaenoic acid C22:6(n3) (2.9% +/- 1.1 vs 5.3% +/- 1.3, p < 0.001), and arachidonic acid C20:4n6 (12.0% +/- 1.6 vs 15.1% +/- 0.6, p < 0.0005). Conversely, the total amount of saturated fatty acids was significantly increased (p < 0.05) and the polyunsaturated/saturated ratio was decreased in the Type 1 diabetic patients (p < 0.00 005). Neither the time from diagnosis, nor C-peptide levels, correlated with parameters indicating a poor metabolic control of Type 1 diabetes. However, C22:6(n-3) and total n-3 content significantly correlated with HbA1c (r = -0.79 and r = -0.88, respectively, p < 0.01), fructosamine (r = -0.71 and r = -0.74, respectively, p < 0.05), and Na+-K+ ATPase activity (maximal rate/Km quotient) (r = 0.78 and r = 0.71, respectively, p < 0.05). In conclusion we have found marked alterations of cell membrane lipid composition in Type 1 diabetic patients. These cell membrane abnormalities in lipid content were related to sodium transport systems and to poor metabolic control. Either diet, or the diabetic state, might be responsible for the observed cell membrane abnormalities. A dietary intervention study might differentiate the role of diet and diabetes in the reported cell membrane alterations.

A study of the lipids and carotenoprotein in the prawn, Penaeus japonicus

The lipid and fatty acid composition of the hepatopancreas and muscle of the prawn, Penaeus japonicus, were analyzed. The hepatopancreas was the main lipid storage organ, triglycerides and phospholipids being its major lipid components, while muscle contained mainly phospholipids. The fatty acid compositions of total lipids from the hepatopancreas and muscle were similar to those in other marine animals. The major fatty acids were palmitic (16:0), oleic (18:1n-9), eicosapentaenoic (20:5n-3), and docosahexaenoic (22:6n-3) acids. The monoglycerides, diglycerides, triglycerides, and cholesterol esters from the hepatopancreas and muscle exhibited similar fatty acid patterns, but each lipid fraction was characterized by a specific paraffin chain composition. A blue carotenoprotein (lambda max = 640 nm) containing astaxanthin was also extracted and purified from the hypodermis of the prawn. This blue carotenoprotein has a molecular weight of ca. 280,000, which is much lower to those given for other crustaceans. The carotenoid prosthetic group was released from the carotenoprotein by the addition of acetone, and showed a hypsochromic shift to 470 nm and the characteristic shape of free ketocarotenoids. TLC, infrared spectroscopy, chemical reduction, spectrophotometry, and qualitative analysis by HPLC were used to identify the astaxanthin as a unique chromophore group of the blue carotenoprotein. Moreover, HPLC studies suggested all-trans-astaxanthin to be the main component, which was accompanied by an epimer and its cis-isomer.

Changes in fatty acid desaturation in hepatic and intestinal tissues induced by intestinal resection

We have studied the activities of delta 9, delta 6 and delta 5 desaturases in rat liver and jejunum when the entero-hepatic circulation was interrupted by either 50 or 75% intestinal resection. Desaturase activities in caecal mucosa were also determined in control and operated rats. Distal small bowel resection significantly altered the activities of desaturase enzymes in liver, jejunum and caecum. Thus, the delta 9 desaturase activity was lower in hepatic microsomes from operated animals, and this decrease was not related to the extent by which the intestine was removed. However, a significant increase in both delta 6 and delta 5 desaturases was found in these animals compared to sham-operated rats, the increase in both desaturases being higher after 75% than after 50% intestinal resection. The activities of delta 9 and delta 5 desaturases were significantly increased in jejunal mucosa of resected rats. The activity of delta 6 desaturase was increased only in 50% resected-animals. An increase in delta 6 desaturase activity was observed in caecal mucosa after resection, together with a decrease in delta 9 desaturase and no change in delta 5 desaturase activities. Enzyme activities were highest in the liver relative to the activity in jejunal and caecal homogenates. In sham rats, the caecal mucosa showed higher delta 9 and delta 6 but lower delta 5 desaturase activities than in jejunal mucosa.

Is hydrogen peroxide involved in the benzyl viologen-mediated in-vivo inactivation of rat liver glutamine synthetase?

After benzyl viologen administration to rats, a decrease in the rat liver glutamine synthetase activity was observed. An increase in the rat liver catalase activity was found concomitantly. In combination with the catalase inhibitor aminotriazole, benzyl viologen again diminished, but markedly, the rat liver glutamine synthetase activity. Moreover, partially purified glutamine synthetase from rat liver underwent rapid inactivation upon aerobic incubation with NAD(P)H and benzyl viologen. This inactivation was prevented by catalase, which suggests that the NAD(P)H/BV2+/O2-dependent system has a role in H2O2 production. Our results suggest that H2O2 is involved in the benzyl viologen-mediated in-vivo inactivation of the rat liver glutamine synthetase. In contrast, benzyl viologen alone or in combination with aminotriazole produced a significant increase of brain glutamine synthetase.

Apparent digestibility of dietary fibre and other components in table olives

The apparent digestibility of the main components of the olive (Olea europaea arolensis) has been studied using young Wistar rats. An appreciable digestibility of fibre was found (of the order of 31% Neutral Detergent Fibre) and a high digestibility of fats (higher than 60%) and sugars (100% of glucose and 76% of fructose). Some 41% of the protein was digested, a relatively low value when compared with other products. If the diet is previously desalted, the digestibility of the components diminishes. There are significant differences in the digestibility of dry matter, fibre, cellulose and lignin, but not in proteins and fat.

Lipid composition, phospholipid profile and fatty acid of rat caecal mucosa

In this study, we examined the lipid composition of rat caecal mucosa, including the fatty acid composition of major phospholipid classes. Phospholipids accounted for 90% of the total lipid, with cholesterol, triacylglycerols, diacylglycerols, fatty acids and cholesterol ester making up the remainder. Therefore, a phospholipid to neutral lipid ration of 9:1 was found. Phosphatidylethanolamine was the predominant phospholipid, with phosphatidylcholine as the second most abundant phospholipid. Cardiolipin, phosphatidylserine, phosphatidylinositol and lysophosphatidylcholine were present in lesser amounts. Sphingomyelin and lysophosphatidylethanolamine were only detected in trace amounts. The major fatty acids present in both the lipid and all phospholipid fractions were palmitate, stearate, oleate, linoleate and arachidonate. Other fatty acids of chain length greater than C20 were only detected in phospholipid fraction and accounted for < 5% of the total fatty acids in this fraction. However, 11.10% of 22:6 (n-3) and 7.17% of 24:0 were detected in phosphatidylserine and lysophosphatidylcholine, respectively. The results are discussed in terms of their possible physiological significance.

Determination of fatty acid and triacylglycerol composition of human adipose tissue

The fatty acid composition of adipose tissue was studied in a population in western Andalusia with a diet in which the fat contribution is mainly from olive oil. The lipid composition of adipose tissue, including the fatty acid composition of triacylglycerols, was examined by capillary gas chromatography. Thirty-five peaks were resolved, ranging in chain length from 12 to 24 carbon atoms, including geometric and positional isomers. The major triacylglycerol was POO, followed by PLO and OOO.

Fatty acid composition and properties of the liver microsomal membrane of rats fed diets enriched with cholesterol

Male rats were fed diets containing olive (OO) or evening primrose (EPO) oil (10% w/w), with or without added cholesterol (1% w/w). After 6-week feeding, the lipid and fatty acid compositions, fluidity, and fatty acid desaturating and cholesterol biosynthesis/esterification related enzymes of liver microsomes were determined. Both the OO and EPO diets, without added cholesterol, increased the contents of oleic and arachidonic acids, respectively, of rat liver microsomes. The results were consistent with the increases in delta 9 and delta 6 desaturation of n-6 essential fatty acids and the lower microviscosity in the EPO group. Dietary cholesterol led to an increase in the cholesterol content of liver microsomes as well as that of phosphatidylcholine (PC). The cholesterol/phospholipid and PC/PE (phosphatidylethanolamine) ratios were also elevated. Fatty acid composition changes were expressed as the accumulation of monounsaturated fatty acids, with accompanying milder depletion of saturated fatty acids in rat liver microsomes. In addition, the arachidonic acid content was lowered, with a concomitant increase in linoleic acid, which led to a significant decrease in the 20:4/18:2 ratio in comparison to in animals fed the cholesterol-free diets. Cholesterol feeding also increased delta 9 desaturase activity as well as membrane microviscosity, whereas it decreased delta 6 and delta 5 desaturase activities. There was a very strong correlation between fluidity and the unsaturation index reduction in the membrane. Furthermore, the activity of hydroxymethylglutaryl-CoA reductase increased and the activity of acyl-CoA:cholesterol acyltransferase decreased in liver microsomes from both cholesterol-fed groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of fatty acid anilides on immune responses of Swiss mice

The possible relationship between fatty acid anilides and the toxic oil syndrome (TOS) which appeared in Spain in 1981 has been debated during recent years. These anilides have been detected as anomalous compound in toxic oils analysed. After treatment with one daily dose of 50 mg/kg of oleilanilide (88.86% pure) for 5 days, animals showed a tendency towards progressive loss of body weight and a significant increase in serum concentration of immunoglobulins. The percentage of suppressor T cells in spleen diminished significantly compared with the control group. Consequently, an increase in the helper T cells/suppressor T cells was also observed. The production of IgM and IgG in culture was significantly higher than in controls and no differences were seen in IgA synthesis. The functional studies of generation of specific IgM, IgA and IgG suppressor cells at variable doses of concanavalin A (Con A) showed paradoxical behaviour of suppressor T cells generated by low doses of Con A. A similar change occurred at higher doses of Con A. These results suggest that low-dose treatment with oleilanilides induces an alteration in the immune response in Swiss mice.

Influence of dietary cholesterol on polyunsaturated fatty acid composition, fluidity and membrane-bound enzymes in liver microsomes of rats fed olive and fish oil

Male rats were fed diets containing olive or marine fish oils (10% w/w) with or without added cholesterol (1% w/w). After six weeks of feeding, the major fatty acid composition, fluidity, fatty acid desaturating and cholesterol biosynthesis/esterification related enzymes of liver microsomes were determined. Both olive oil and marine fish oil diets, without added cholesterol, enriched content of oleic and docosahexaenoic acids, respectively, of rat liver microsomes. The results were consistent with reduction in delta 6 and delta 5 desaturation of n-6 essential fatty acids and higher fluidity in the marine origin oil group. Inclusion of cholesterol into diets resulted in decreased membrane arachidonic acid content, with concomitant increase in linoleic acid content. Cholesterol feeding also decreased delta 6 and delta 5 desaturase activities, as well as membrane fluidity. Furthermore, the activity of acyl-CoA:cholesterol acyltransferase decreased, whereas the activity of hydroxymethylglutaryl-CoA reductase increased, in liver microsomes from both cholesterol-fat groups.

Determination of phospholipid fatty acid and triacylglycerol composition of rat caecal mucosa

The lipid composition of rat caecal mucosa, including the fatty acid composition of phospholipids and triacylglycerols, has been examined by capillary gas chromatography. Thirty-seven peaks were resolved, ranging in chain length from 12 to 24 carbon atoms. Preliminary identification of fatty acids by comparison with authentic standards was confirmed by gas chromatography-mass spectrometry using electron-impact ionization. The neutral and polar components were examined. Fatty acid methyl esters were quantified in absolute amounts with respect to the percentage of total phospholipid and triacylglycerols. The results show significantly higher levels of 16:0, 18:0, 18:1(n-9), 18:1(n-7), 18:2(n-6) and 20:4(n-6) in phospholipids, and higher levels of 16:0, 18:1(n-9) and 18:2(n-6) in triacylglycerols. On the other hand, analysis of caecal triacylglycerols revealed sn-glycerol-palmitate-oleate-palmitate, sn-glycerol-palmitate-linoleate-palmitate and sn-glycerol-palmitate-linoleate-oleate as major components.

Effect of benzyl viologen on the phospholipid fatty acid composition and some properties in hepatic microsomal membrane of rats

The effect of benzyl viologen (a stimulator of free radical production in cells) on lipid composition, fluidity and enzymes involved in both polyunsaturated fatty acid biosynthesis and cholesterol metabolism was studied in liver microsomal membrane of adult rats. In viologen-treated animals, a significant decrease in the levels of free cholesterol and cholesteryl esters, accompanied to a decrease at the free cholesterol/phospholipid ratio, were observed. The levels of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase and acyl-coenzyme A: cholesterol acyltransferase (ACAT) were also lower in viologen-treated rats than in controls. Linoleic and arachidonic acids were both severely lower while docosatetraenoic, docosapentaenoic and docosahexaenoic acids were significantly higher as compared with controls. Furthermore, a decrease in monounsaturated/saturated ratio was found. In addition, the treatment evoked a depression in the fatty acid desaturation complex, with a diminish of delta 9, delta 6 and delta 5 desaturase activities in microsomal membrane. It was concluded that changes in phospholipid microsomal fatty acid and cholesterol content could be directly responsible for changes in membrane fluidity and function, and that extensive yield of docosahexaenoic acid may serve to maintain the physical characteristics of particular domains against oxidative stress caused by benzyl viologen treatment.

Effect of benzyl viologen on the fatty acid composition of rat liver

The influence of subacute treatment with benzyl viologen (a stimulator of free radical production in cells) on the fatty acid content of rat liver has been analyzed. Lipid storage, essentially characterized by lamellated inclusions, developed as we reported previously (Muriana et al., Exp. Pathol., 32 (1987) 65-72). A substantial increase in liver total lipid, phospholipids and triacylglycerols was found during viologen treatment in rats. The composition in fatty acids was profoundly influenced by the experimental conditions, but to different degrees in different lipid classes.

Caecal and colonic uptake of both linoleic acid and cholesterol in rats following intestinal resection

Caecal and colonic uptake of both linoleic acid and cholesterol were studied in rats after distal small bowel resection (DSBR). The results showed that the surgical operation increased the caecal and colonic uptake of linoleic acid. Supplementation with linolenic acid inhibited caecal and colonic uptake of linoleic acid. Experiments carried out in the presence of rotenone and ouabain suggest that facilitated diffusion is the predominant mechanism of caecal and colonic linoleic acid absorption, at least at low concentrations. An increase in caecal and colonic uptake of cholesterol was observed after the surgical operation. The study showed that facilitated diffusion seems to be the mechanism of linoleic acid absorption in the caecum and colon, and that both organ growth and changes in transport function of the epithelial cells of caecum and colon appear to be involved in the adaptive response of the bowel to intestinal resection.

Changes in uptake of linoleic acid and cholesterol by jejunal sacs of rats in vitro, after distal small-bowel resection

Both linoleic acid and cholesterol uptake were studied in small-intestinal sacs of rats in vitro after distal small-bowel resection (DSBR). The relationship between linoleic acid concentration and its absorption was non-linear at low concentrations and became linear at high concentrations in the three groups of animals. These observations indicate that a concentration-dependent dual mechanism of transport is operative in linoleic acid intestinal uptake. Experiments with rotenone and ouabain suggest that a facilitated diffusion is the predominant mechanism of absorption at low concentrations, whereas at high concentrations simple diffusion is predominant. The apparent kinetic constants of linoleic acid uptake (Kd, Kt, and Vmax) increased after DSBR. The uptake of linoleic acid is, however, influenced by the simultaneous presence of linolenic acid, the inhibition constant being decreased after the surgical operation. After the surgical operation an increase of cholesterol uptake was observed, with a parallel enhancement in the apparent mass-transfer coefficient (Kd). Taken together, these results suggest that both organ growth and changes in transport function of the enterocytes appear to be involved in the adaptive response of the bowel to intestinal resection.

Effect of distal small bowel resection on ACAT activity and microsomal lipid composition in rat small intestine

1. The acyl-CoA:cholesterol acyltransferase (ACAT) activity and lipid composition of intestinal microsomal membrane were investigated 6 weeks after both 50 and 75% distal small bowel resection (DSBR). 2. No changes in both microsomal ACAT activity and cholesteryl ester levels were found, while microsomal non-esterified cholesterol content was increased after the surgical operation. 3. The total phospholipid content of the microsomes did not change as a result of DSBR. 4. The microsomal phospholipid fatty acid composition showed a significant increase in saturated fatty acids together with no changes in both total monounsaturated and total polyunsaturated fatty acids after resection. 5. An increase in the levels of linoleic acid accompanied by a decrease in arachidonic acid was found in remnant intestine of resected rats.

Comparative effects of feeding different fats on fatty acid composition of major individual phospholipids of rat hearts

Comparative effects of feeding dietary linoleic (corn oil), oleic (olive oil), alpha-linolenic (soybean oil) and polyunsaturated fatty acids (fish oil) on lipid content and fatty acid composition of major individual phospholipids of rat hearts were examined. Feeding different diets did not result in lipid accumulation in the heart. Total triglyceride, nonesterified fatty acid, cholesteryl ester and phospholipid levels of heart tissue were not affected by the type of dietary fatty acid. However, heart free cholesterol levels decreased in both animals fed the olive and the fish oil diets. The percentage of individual phospholipids, phosphatidylcholine (PC), phosphatidylethanolamine (PE) and cardiolipin (CL) did not modify by changes in the dietary fat composition. Heart tissue from animals fed on olive oil were enriched with 18:1 (n-9 + n-7) fatty acid in all phospholipid fractions. Animals fed corn oil contained higher proportions of 18:2 (n-6) for PC, PE and CL, and the ingestion of the soybean oil diet increased 18:2 (n-6) for PC and CL in the same proportion as the ingestion of the corn oil diet. The levels of 22:6 (n-3) were increased in the fish oil-fed group, accompanied by both a decrease in total (n-6) fatty acids and an increase in total (n-3) fatty acids in the three phospholipid fractions. The 20:5 (n-3) was only detected in these animals. These results show that olive oil is as effective as fish oil in reducing heart cholesterol content and support earlier works suggesting the role of fish oil in preventing cardiovascular disease.

Changes in both acyl-CoA:cholesterol acyltransferase activity and microsomal lipid composition in rat liver induced by distal-small-bowel resection

The acyl-CoA:cholesterol acyltransferase (ACAT) activity and lipid composition of hepatic microsomal membrane were investigated 6 weeks after both 50 and 75% distal-small-bowel resection (SBR). A significant decrease in hepatic cholesteryl ester levels was observed after SBR, with a significant increase in the cholesteryl ester content of the livers of 75% SBR compared with the 50% SBR. Hepatic total acylglycerols, free cholesterol and phospholipid levels were not modified after the surgical operation. Microsomal free cholesterol was increased after both 50 and 75% SBR. However, a decrease in both microsomal ACAT activity and cholesteryl ester levels were found in microsomes (microsomal fractions) of resected rats, both changes being higher after 75 than after 50% resection. The total phospholipid content of the microsomes did not change after the surgical operation. The microsomal phospholipid fatty acid composition indicated higher changes after 75 than after 50% SBR. These results demonstrated that, in resected animals: (1) the activity of the enzyme responsible for catalysing cholesterol esterification (ACAT) is decreased, and (2) hepatic microsomal free cholesterol does not appear to influence the activity of ACAT.