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PubMed1981

Effect of dietary lipids on composition and glucose utilization by rat adipose tissue.

Feeding rats diets rich in either safflower oil or coconut oil resulted in a significant change in the lipid composition of epididymal fat pads as compared with those obtained from rats fed a commercial stock diet. A safflower oil diet resulted in an increase in tissue cholesterol and a decrease in phospholipid concentration as compared with the stock diet. A coconut oil diet resulted in a decrease in both tissue cholesterol and phospholipid concentrations as compared with the stock diet. Adipose tissue fatty acid composition was also altered due to these dietary manipulations. Glucose utilization by adipose tissue from animals fed the safflower oil diet was 2 and 10 times greater than glucose utilization by adipose tissue from animals fed the stock and coconut oil diets, respectively. The coconut oil diet resulted in an increase in the percentage of glucose incorporated into adipose tissue diglycerides, free fatty acids and cholesterol esters and a decrease in the percentage of glucose incorporated into triglycerides as compared with animals fed the stock or safflower oil diet. The incorporation of glucose into adipose tissue fatty acids was depressed by a saturated fatty acid diet as compared with either a polyunsaturated fatty acid diet or the stock diet.

Adipose Tissue↗
PubMed1989

Digestion and absorption of fish oil by neonatal piglets.

In order to establish the digestibility and absorption of fish oil, 18 unsuckled, newborn piglets were tube-fed an amount of fish oil calculated to provide the piglets' maintenance energy needs for 12 h. After fat administration the piglets were either intubated with 25 ml of fat-free milk replacer per h, or fasted. The digesta of the stomach, small intestine, and large intestine (digesta plus feces) were collected 12 h after fish oil intubation. Disappearance of total extractable fat was 95 +/- 1 and 94 +/- 1% for fed and fasted piglets, respectively. True absorption of the lipid was calculated from the disappearance of eicosapentaenoic acid and was 99% for both fed and fasted piglets. Nearly 50% of the stomach lipid was as diglycerides and free fatty acids, suggesting that hydrolysis of the fish oil was initiated in the stomach. Small intestinal lipid was 63-65% free fatty acids, indicating that the piglet pancreatic lipase was of sufficient activity to hydrolyze fish oil triglyceride. Neonatal piglets appeared to have ample capacity to digest and absorb fish oil, which supports the concept that lipid supplementation could improve the energy status of the newborn piglet.

Absorption↗
PubMed2002

Glyceride stearic acid content and structure affect the energy available to growing rats.

To better understand the relative absorption of 18:0, specific structured triglycerides (STG) with varied ratios of 18:0 and short-chain organic acids (2:0, 3:0, 4:0) were compared with naturally occurring 18:0 in cocoa butter and to other mono- and diglycerides (DGs) containing 18:0. A bioassay for available fat energy was developed for growing Sprague-Dawley rats fed reduced energy from a control diet containing an American Heart Association (AHA) fat blend to generate 60 or 80% normal growth. The resulting standard growth curve was applied to the test fats, including cocoa butter and six glycerides, which were blended 3:1 with the AHA blend (to ensure EFA sufficiency) and pair-fed to match intake of control rats (AHA diet, 80% normal growth). Available energy from test fats ranged from 30 to 12 kJ/g (7.1 to 2.9 kcal/g) for cocoa butter to 18:0-DG, respectively, with the mean of the four different STG being 22 kJ/g (5.2 kcal/g). Energy available from test fats was negatively related to total 18:0 in the STG (r = -0.90; P < 0.001) and fecal dry weight (r = -0.92; P < 0.001); the effect was greater for monoglyceride (monolong-18:0) than for DG (dilong-18:0) but was not related to fecal 18:0. Compared with monoglyceride-18:0, available energy was increased or decreased when short-chain organic acids (SCOA) were added to form triglycerides, depending on the addition of butyrate or acetate, respectively. The different fat sources altered the available energy without apparent changes in lipoproteins or body composition. Thus, the reduced energy available from a glyceride containing 18:0 is determined by its total 18:0 and reflects the mono- or dilong chain character of the glyceride, its content of SCOA and triglyceride structure or organization per se.

Animals↗
PubMed1986

Effects of Ca2+ on ethanolaminephosphotransferase and cholinephosphotransferase in rabbit platelets.

The effects of Ca2+ on ethanolaminephosphotransferase [EC 2.7.8.1] and cholinephosphotransferase [EC 2.7.8.2] activities in rabbit platelet membranes were studied using endogenous diglyceride and CDP-[3H]ethanolamine or CDP-[14C]choline as substrates. Both transferases required Mn2+, Co2+, or Mg2+ as a metal cofactor and the optimal concentrations of the metals for both activities were about 5, 10, and 5 mM, respectively. When 5 mM Mg2+ was used as a cofactor, both transferase activities were inhibited by a low concentration of Ca2+ (half maximal inhibition at approx. 15 microM). In the presence of 5 mM Mn2+, however, approx. 5 mM Ca2+ was required to produce half maximal inhibition. The Ca2+-induced inhibition was reversible and the rate of the inhibition was not affected either by the concentrations of the CDP-compound or by exogenously added diacylglycerol. The relationship between Ca2+ and both Mg2+ and Mn2+ on the transferase activities was competitive. 45Ca2+ binding (and/or uptake) to the platelet membranes was inhibited by Mn2+, Mg2+, and Co2+, in a concentration-dependent manner. However, the inhibitory effects of the three metal ions on the total Ca2+ binding (and/or uptake) did not correlate with the activation of both transferase activities by the three metal ions in the presence of Ca2+. These results suggest that both transferase activities are regulated by low concentrations of Ca2+ in the presence of optimal concentrations of Mg2+, and that the inhibition is mediated directly by Ca2+, which interacts with a specific metal cofactor binding site(s) of the transferases.

Animals↗
PubMed1993

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.

Animals↗
PubMed1976

Metabolism of triacylglycerol in Mycobacterium smegmatis.

Mycobacterium smegmatis cells incorporated [1-14C]oleic acid into triacylglycerols (TG) from the medium more rapidly than shorter chain fatty acids, caprilic and butyric acids. This incorporation was inhibited more strongly by 10(-3) M N-ethylmaleimide than by 10(-3) M KCN. [14C]TG in the bacterial cells was utilized when the cells were in poor nutritional conditions, such as phosphate buffer (pH 7.0) containing oleic acid. Accumulation of TG was observed in the cells at late stages of growth. Diglyceride acyltransferase [EC 2.3.1.20] activity was detected in a cell-free extract from this bacterium. The pH optimum of this enzyme was between pH 7 and 9. F- and Tween 20 showed remarkable enhancing and inhibitory effects, respectively.

Acyltransferases↗
PubMed1977

Determination of molecular species of phospholipids from thermophilic bacterium PS3 by mass chromatography.

The molecular species of phosphatidylethanolamine, phosphatidyglycerol and cardiolipin of thermophilic bacterium PS3 were determined by a new and simple mass chromatographic technique. The fatty acyl groups of these compounds, unlike those of usual phospholipids, were all saturated and were mixtures of even and odd numbered carbon chains; their [M-CnH2n+1-COOCH2]+ and [M-Cn+1H2n+3COO]+ peaks overlapped. Thus, the acetyldiglycerides derived from these phospholipids were subjected to a combination of mass chromatography using chemical ionization with NH3 and treatment of the phospholipids with phospholipase A2 [EC 3.1.1.4]. These three phospholipids had similar patterns of diglycerides. Expressed as R1 : R2, %, they were found to be 14:14,0-1%, 15:14,0-4%, 15:15, 22-23%, 16:15, 16-20%, 17:15, 28-32%, 17:16, 6-9%, 18:15, 7-13%, 17:17, 3-6%, and 18:16, 0-1%. These results should be of significance in connection with the high stability of the biomembranes of this bacterium.

Bacteria↗
PubMed1978

Role of phospholipid in adrenaline-induced lipolysis and cyclic AMP production.

Lipid micelles consisting of a glyceride mixture (triolein, diolein, and monoolein) and lecithin bound adrenaline-14C more strongly than did micelles consisting of the glyceride mixture only. Lipid micelles consisting of the glyceride mixture and phosphatidic acid also bound adrenaline-14C effectivily, whereas lipid micelles consisting of the glyceride mixture and diglyceride, obtained from lecithin, did not bind the hormone strongly. Both phenoxybenzamine (an alpha- blocker) and propranolol (a beta-blocker) strongly inhibited the association between adrenaline-14C and lipid micelles consisting of the glyceride mixture and lecithin. Propranolol, inhibited adrenaline-induced lipolysis in both fat cells and fat globules, whereas, phenoxybenzamine, did not affect adrenaline-induced lipolysis. Both agents reduced adrenaline-induced adenyl-cyclase activation in fat cell ghosts. Phospholipid was also found to be related with adrenaline-mediated adenylcyclase activation.

Adenylyl Cyclases↗
PubMed1982

Synthesis of various phospholipids from 2-acyl lysophospholipids by Escherichia coli extract.

When 2-[14C]acyl lysophosphatidylethanolamine was incubated with the envelope fraction of E. coli in the presence of Mg2+ ion, phosphatidylethanolamine, acylphosphatidylglycerol and free fatty acid were produced. When 2-[14C]acyl lysophosphatidylglycerol was examined similarly, six phospholipids as well as free fatty acid were produced. These were dilysocardiolipin, lysocardiolipin, phosphatidylglycerol, cardiolipin, bis(monoacylglycero)phosphate and acylphosphatidylglycerol; they were identified by thin layer chromatography, acetolysis and mild alkaline hydrolysis. Studies with an E. coli mutant which is deficient in cardiolipin synthase showed that dilysocardioilipin, lysocardiolipin and cardiolipin were synthesized by cardiolipin synthase. Bis(monoacylglycero)phosphate as well as acylphosphatidylglycerol was produced by acylphosphatidylglycerol synthase. While phosphatidylglycerol and cardiolipin were produced predominantly from 2-acyl lysophosphatidylglycerol, almost the same amounts of dilysocardiolipin, lysocardiolipin and bis(monoacylglycero)phosphate were produced from the 1-acyl and 2-acyl isomers. Metabolites of 2-[14C]acyl lysophosphatidic acid were also examined. Phosphatidic acid, acylphosphatidylglycerol, free fatty acid and monoglyceride were produced, together with a small amount of diglyceride.

Escherichia coli↗
PubMed1984

Structural studies of Fc receptors. V. Effect of phospholipase C treatment on the binding activities of the Fc receptor of macrophage or its isolated plasma membrane.

The effect of phospholipase C treatment on the binding activity of the Fc receptor of guinea pig macrophage was studied to analyze the interaction of the Fc receptor with membrane phospholipids necessary for the activity. It was confirmed by subcellular fractionation that the receptor is localized on the plasma membrane. Treatment of the whole cell or isolated plasma membrane with phospholipase C of Clostridium perfringens diminished the binding of soluble IgG2-immune complex to Fc receptors on the cell or membrane. On the other hand, phospholipase C of Bacillus cereus did not affect the activity when it acted on the whole cell but it did diminish the activity when it acted on the isolated plasma membrane. Analysis of the phospholipids of untreated and treated macrophages or plasma membrane showed that phosphatidylcholine molecules, particularly those located in the membrane (not accessible to attack from the cell surface by phospholipase C of B. cereus), appear to be crucial for efficient interaction of macrophage Fc receptors with immune complex. Ligand-binding experiments with macrophages showed that the diminished binding activity was due to a decrease of the avidity for immune complex, but did not seem to be due to a decrease in the number or affinity of Fc receptors for monomeric IgG2. Taken together with the previous results which demonstrated that Fc receptors which had apparently lost the activity due to delipidation could be reconstituted with phosphatidylcholine but not with most other phospholipids, the results seem to indicate that the diminution of the binding activity to the immune complex of macrophage or its plasma membrane caused by phospholipase C treatment is due to the impairment of multivalent interaction between Fc receptor molecules on the membrane and IgG2 molecules in the immune complex, probably as a result of the loss of interaction of the head groups of phospholipids with Fc receptor molecules and the change in membrane properties resulting from the increase of diglycerides.

Animals↗
PubMed1991

Role of phospholipase in generating lipid second messengers in signal transduction.

Many lipids or lipid-derived products generated by phospholipases acting on phospholipids in membranes are implicated as mediators and second messengers in signal transduction. Our current understanding of the primary sequence relationships within the class of extracellular phospholipase A2's and among the numerous forms of the mammalian phosphatidylinositol-specific phospholipase C's is reviewed. New results suggesting roles for these phospholipases as well as other phospholipases such as phospholipase C and D acting on phosphatidlycholine in generating arachidonic acid for eicosanoid biosynthesis, inositol phosphates for Ca2+ mobilization, and diglyceride for protein kinase C activation through receptor-mediated processes, are discussed. In addition, the possible role of phospholipases acting on sphingolipids such as sphinglomyelinase in generating lipid mediators is considered.

Arachidonic Acid↗
PubMed1990

Oligodendrocyte cell surface recognized by a novel monoclonal antibody specific to sulfatide.

A rat monoclonal antibody (OL-1) was obtained by in-vitro immunization of rat spleenocytes with paraformaldehyde-fixed primary cultured glial cells derived from newborn rat brain and subsequent fusion with a rat myeloma cell line. The antibody secreted by the hybridoma immunostains live rat and mouse oligodendrocytes in primary and secondary cultures. The antibody binds specifically to oligodendrocytes and myelin structures in-situ. Radioimmunolabelling assays with a number of purified glycolipids offer thin layer chromatography separation show that OL-1 antibody binds strongly to sulfatide and to a lesser extent to galactosyl diglyceride.

Animals↗
PubMedDate not supplied

Lipid composition of prepartum human mammary secretion and postpartum milk.

Changes in lipid composition of mammary secretions of five women were studied at two prepartum periods and compared with composition of colostrum, transitional, and mature human milk. Fat content was approximately 1 g/dl during early (-42.0 days before parturition) and late (-9.5 days) prepartum periods and increased to 3-4 g/dl in colostrum (3.0 days post partum), transitional (7.2 days), and mature milk (56.2 days). Most of the lipid present was triglyceride either pre- (93%) or post- (97%) partum. All fat globule core lipids, with the exception of 1,3-diglycerides, increased from prepartum concentrations to levels usually found in milk. Prepartum secretions contained higher amounts of the membrane components, phospholipid (3.2 g/dl), cholesterol (2.3 g/dl), and cholesteryl ester (1.1 g/dl), which declined postpartum to 0.65, 0.37, and 0.09 g/dl, respectively. Thus, the content of core lipids exhibited an opposite pattern to the content of membrane lipids pre- and postpartum. With regard to synthesis of fatty acids, prepartum secretory mechanisms appeared to be very similar to those occurring postpartum since fatty acid composition of prepartum secretions closely resembled that of postpartum milk.

Breast↗
PubMed1997

Protein kinase C mediated anti-proliferative glucocorticoid-sphinganine synergism in cultured Pollard III prostate tumor cells.

PURPOSE: Experimental effort focused on the growth inhibition of an androgen-resistant prostatic carcinoma, using pharmacological inhibition of protein kinase C (PKC) as the therapeutic target. MATERIALS AND METHODS: Studies were performed in cell culture using the Pollard (PA) III androgen-insensitive spontaneous rat prostate tumor cells, and the human prostate tumor lines, PC-3 and LnCaP. Pharmacological agents included steroid hormones and PKC modulators; measured parameters of tumor growth/function included cell number, PKC activity and sphingolipid metabolism. RESULTS: Triamcinolone (TA) and sphinganine synergized to inhibit the proliferation rate of PA III prostate tumor cells by converging through separate mechanisms to inhibit protein kinase C. At five days of cell culture, 0.1 microM TA reduced both the soluble and particulate forms of PKC in association with a 35-40% reduction in cellular proliferation. Exogenous sphinganine, a competitive inhibitor at the regulatory domain of PKC had no anti-proliferative effect at 1 microM, but in combination with TA synergized to reduce proliferation 80-90%, three days in advance of any detectable inhibitory effect of TA alone on cell number. TA produced no discernable stimulation of endogenous free sphingosine production as evidenced by the lack of an effect on the activity of neutral membrane sphingomyelinase or in the turnover of total cellular sphingomyelin. Phorbol esters, but not cell permeable diglycerides, prevented the TA + sphinganine effect suggesting that a stable long term PKC activation was required for reversal. Steroid specificity studies of the synergistic response revealed that while other glucocorticoids mimicked TA, aldosterone was less active and representatives of the three major classes of sex steroids were inert. Tests of sphinganine specificity demonstrated that calphostin C, a chemically unrelated inhibitor of the regulatory site of PKC, also produced a supra-additive interaction with TA. Ceramides (C2 & C6), which were closely related chemically to sphinganine but lacked affinity for the regulatory subunit of PKC, were inactive in this system. Analyses of the cellular specificity of the TA-sphinganine synergism using the human prostate carcinoma cell lines PC-3 and LnCap revealed a true synergistic growth inhibition in the glucocorticoid receptor positive PC-3 line and no significant interaction in the glucocorticoid receptor negative LnCap cells. CONCLUSIONS: TA-induced reduction of PKC concentration coupled with sphinganine antagonism of PKC activation contributed to in a synergistic growth inhibition of an androgen resistant prostatic carcinoma.

Animals↗
PubMed2003

Letting lipids go: hormone-sensitive lipase.

PURPOSE OF REVIEW: Despite their pathophysiological importance, the molecular mechanisms and enzymatic components of lipid mobilization from intracellular storage compartments are insufficiently understood. The aim of this review is to evaluate the role of hormone-sensitive lipase in this process. RECENT FINDINGS: Hormone-sensitive lipase exhibits a broad specificity for lipid substrates such as triglycerides, diglycerides, cholesteryl esters, and retinyl esters and the enzyme is in a wide variety of tissues. The high enzyme activity in adipose tissue was considered rate-limiting in the degradation of stored triglycerides. This view of a single enzyme controlling the catabolism of stored fat was challenged by recent findings that in hormone-sensitive lipase deficient mice adipose tissue triglycerides were still hydrolyzed and that these animals were leaner than normal mice. These results indicated that in adipose tissue hormone-sensitive lipase cooperates with other yet unidentified lipases to control the mobilization of fatty acids from cellular depots and that this process is coordinately regulated with lipid synthesis. Induced mutant mouse lines that overexpress or lack hormone-sensitive lipase also provided evidence that hormone-sensitive lipase-mediated cholesteryl ester hydrolysis is involved in steroid-hormone production in adrenals and affects testis function. Finally, hormone-sensitive lipase deficiency in mice results in a lipoprotein profile characterized by low triglyceride and VLDL levels and increased HDL cholesterol concentrations. SUMMARY: The 'anti-atherosclerotic' plasma lipoprotein profile and the fact that hormone-sensitive lipase deficient animals become lean identifies the inhibition of hormone-sensitive lipase as a potential target for the treatment of lipid disorders and obesity.

Adipose Tissue↗
PubMed1983

Stimulation of aflatoxin biosynthesis by lipophilic epoxides.

Epoxy fatty acids added to the culture media either with the inoculum or at the end of exponential growth phase stimulated aflatoxin production by toxigenic strains of Aspergillus flavus and Aspergillus parasiticus. This effect did not appear when the unsaturated fatty acids used for the synthesis of the epoxides and the polyhydroxyacids (which can be considered to be derived from the opening of the oxirane ring) replaced the epoxides in the culture media. No significant differences were detected in the lipid fractions (diglycerides, sterols, triglycerides, free fatty acids, sterol esters) extracted from the mycelia grown in the presence of any of the fatty acid derivates.

Aflatoxins↗
PubMed1992

The esterification of fatty acids by Staphylococcus aureus fatty acid modifying enzyme (FAME) and its inhibition by glycerides.

Fifty-five randomly selected Staphylococcus aureus strains were examined for fatty acid modifying enzyme (FAME) production. Of these, 20.4% did not elaborate the enzyme. Amongst the remaining strains, the lowest level produced in culture was 0.1 unit/10(9) cocci and the maximum was 2.01 U/10(9) cocci; the median level was 0.4 U/10(9) cocci. In a series of straight-chain saturated fatty acids with 11-24 carbons, all could be esterified by FAME. However, those with 15-19 carbons were generally better substrates than the others. For a particular chain length, the unsaturated forms were better substrates than the saturated form. Triglycerides with unsaturated fatty acid side chains were potent inhibitors of FAME. Diglycerides were almost as active as triglycerides, but monoglycerides were much less inhibitory. FAME was purified by gel filtration followed by hydrophobic interaction chromatography on hexyl agarose. FAME and lipase may have a role in determining the survival of S. aureus in lesions.

Acyltransferases↗