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PubMed1982

Effects of dietary cholesterol and type of dietary carbohydrate on hepatic and plasma glycerides and phospholipids in the gerbil.

The influence of dietary cholesterol at levels of 0.01-0.5% (by weight) and carbohydrate type (starch, sucrose or a starch-sucrose mixture) on levels and composition of hepatic and plasma glycerides in the male Mongolian gerbil (Meriones unguiculatus) was studied. Hepatic and plasma triglyceride (TG) levels were generally higher with dietary cholesterol supplementation (0.1 and 0.5%), and animals fed sucrose diets exhibited very low levels of hepatic and plasma TG. The mixed carbohydrate (starch-sucrose) did not affect glycerides in a way that could be interpolated from feeding starch or sucrose diets alone. The percent of 16:0 in liver TG was depressed with cholesterol-feeding (at the 0.5% level only), whereas the percent of 18:1 was elevated. Sucrose diets produced higher percentages of 18:0 in liver TG. Dietary cholesterol elevated concentrations of plasma but not liver phospholipid (PL). Percentages of 20:40 omega 6 and 22:6 omega 3 acids in liver and plasma PL were significantly depressed by cholesterol supplementation, whereas the percent of 18:2 in liver PL was higher when feeding cholesterol and starch (no sucrose). Dietary cholesterol produced higher levels of hepatic 1,2-diglyceride with lower percentages of 18:0 and 20:4 omega 6 and higher percentages of 18:1 and 18:2. Dietary cholesterol may possibly influence fatty acid elongation and desaturation reactions as well as transacylation reactions in phospholipid synthesis. In this regard, compositional data suggested a suppressing effect of dietary cholesterol on 22:6 omega 3 formation as exemplified by a 40% diminution in the docosahexaenate content of hepatic phosphatidylethanolamine in gerbils fed a 0.5% cholesterol diet for only 7 days.

Animals↗
PubMed1986

Studies on glucosyltransferase and endogenous glucosyl acceptor in Bacillus cereus AHU 1030 membranes.

A glucosyltransferase, extracted from the membranes of Bacillus cereus AHU 1030 with Tris-HCl buffer containing 0.1% Triton X-100 at pH 9.5, was separated from an endogenous glucosyl acceptor by chromatography on DEAE-Sepharose CL-6B subsequent to chromatography on Sepharose 6B. Structural analysis data showed that the glucosyl acceptor was a glycerol phosphate polymer linked to beta-gentiobiosyl diglyceride. The enzyme catalyzed the transfer of glucosyl residues from UDP-glucose to C-2 of the glycerol residues of repeating units of the acceptor. On the other hand, a lipoteichoic acid which contained 0.3 D-alanine residue per phosphorus was isolated from the cells by phenol treatment at pH 4.6. Except for the presence of D-alanine, this lipoteichoic acid had the same structure as the glucosyl acceptor. The rate of glucosylation observed with the D-alanine-containing lipoteichoic acid as the substrate was less than 40% of that observed with the D-alanine-free lipoteichoic acid, indicating that the ester-linked D-alanine in the lipoteichoic acid interferes with the action of the glucosyltransferase. The enzyme also catalyzed glucosylation of poly(glycerol phosphate) which was synthesized in the reaction of a separate enzyme fraction with CDP-glycerol. Thus, it is likely that the glucosyltransferase functions in the synthesis of cell wall teichoic acid.

Bacillus cereus↗
PubMed1987

Purification and characterization of calcium/phospholipid-dependent kinase from adult human epidermis.

Tumor-promoting phorbol esters such as 12-0-tetradecanoylphorbol-13-acetate (TPA) cause epidermal inflammation and hyperplasia similar to that observed in psoriasis. Recent evidence suggests that these effects are mediated by a calcium/phospholipid-dependent protein kinase (protein kinase C), which is quantitatively the major cellular phorbol ester receptor. This report describes the partial purification and biochemical properties of this enzyme from adult human epidermis. Protein kinase C activity was purified 30-fold from high speed supernatants prepared from homogenates of keratome biopsies obtained from healthy volunteers. The partially purified preparation had a specific activity of 1.2 nmol/min/mg protein and an apparent molecular weight of 79,400. Activity was dependent on the presence of calcium and phosphatidylserine. At low calcium concentration (less than 0.1 mM) activity was greatly stimulated by 1,2-dioleoylglycerol. TPA mimicked the effect of diglyceride on enzyme activity, and the partially purified enzyme specifically bound phorbol dibutyrate (Kd = 2 nM). Protein kinase C activity was also present in the membrane fraction from adult human epidermis, and possessed properties similar to those of the cytosolic enzyme. We conclude that protein kinase C is present in human epidermis and is activated by TPA in a manner similar to that described for this enzyme from other tissues. These data lay the foundation for studying the role of protein kinase C in the regulation of epidermal growth and maturation.

Adult↗
PubMed2006

Metabolically active functional food ingredients for weight control.

The scale of the obesity epidemic creates a pressing consumer need as well as an enormous business opportunity for successful development and marketing of food products with added benefits for weight control. A number of proposed functional food ingredients have been shown to act post-absorptively to influence substrate utilization or thermogenesis. Characteristics and supporting data on conjugated linoleic acid, diglycerides, medium-chain triglycerides, green tea, ephedrine, caffeine, capsaicin and calcium, are reviewed here, giving examples of how these could act to alter energy expenditure or appetite control. Consideration is also given to other factors, in addition to efficacy, which must be satisfied to get such ingredients into foods. We conclude that, for each of the safe, putatively metabolically active agents, there remain gaps in clinical evidence or knowledge of mechanisms, which need to be addressed in order to specify the dietary conditions and food product compositions where these ingredients could be of most benefit for weight control.

Adipose Tissue↗
PubMed1981

The influence of divalent cations and substrate concentration on the incorporation of myo-inositol into phospholipids of isolated bovine oligodendrocytes.

The incorporation of myo-inositol into phosphatidylinositol by two routes (CTP-independent and CTP-independent) has been investigated in homogenates prepared from isolated bovine oligodendrocyte perikarya. The CTP-dependent route has the higher maximum velocity of inositol incorporation and can utilise either Mn2+ or Mg2+ as a divalent ion cofactor. This route of inositol incorporation is also strongly inhibited by Ca2+ ions at concentrations less than 1 mM. The primary site of the inhibitory action appears to be the enzyme CDP-diglyceride inositol phosphatidyl transferase (EC 2.7.8.11) though synthesis of CDP-diacylglycerol is also inhibited by endogenous Ca2+ present in the oligodendrocyte homogenate. In contrast, CTP-independent inositol incorporation into phosphatidylinositol is only stimulated by Mn2+ (Zn2+,Cu2+, Mg2+, Ca2+ and Co2+ are ineffective) and is not inhibited by Ca2+, at least up to a concentration of 1 mM.

Animals↗
PubMed1981

Characterization of alkylgalactolipids from calf brain by high performance liquid chromatography.

Minor nonpolar galactolipids were isolated from the total lipids of calf brain stem by column chromatography and were separated by preparative thin-layer chromatography into four groups. The material recovered from the bottom band of the thin-layer chromatography consisted of monogalactosyl diglyceride and its 1-0-alkyl isomer, alkylgalactolipid, present in a molar ratio of 11:9. After perbenzoylation, they were separated by preparative thin-layer chromatography and characterized. The fatty acid compositions of these lipids were similar to each other and to those of the ester-linked fatty acids of cerebroside esters. The major alkyl group of alkylgalactolipid was palmityl, and the other, minor componenents were oleyl, myristyl, and stearyl ethers. Perbenzoylated derivatives of these lipids were further separated by reverse-phase high performance liquid chromatography. The chromatograms from these two lipids were similar; however, most of the peaks were still mixtures of homologs containing different fatty acids or an alkyl group.

Animals↗
PubMed1983

Stimulation of free fatty acid and diacylglycerol accumulation in cerebrum and cerebellum during bicuculline-induced status epilepticus. Effect of pretreatment with alpha-methyl-p-tyrosine and p-chlorophenylalamine.

The pool size and composition of free fatty acids (FFA) and diglycerides (DG) from the cerebrum and cerebellum of rats undergoing bicuculline-induced seizures were studied. A fourfold increase in cerebral FFA occurred 3-4 min after bicuculline injection; arachidonic and stearic acids were the principal fatty acids accumulated. Cerebellar FFA also increased, but to a lesser extent. An increased production of arachidonic acid took place in the cerebrum as a function of time after bicuculline injection. Other fatty acids produced were oleic, palmitic, and docosahexaenoic acids. A twofold increase in cerebral arachidonic acid was seen at the time of the first generalized tonic-clonic convulsion. However, a 13- to 17-fold increase in arachidonic acid was seen approximately 5-6 min after bicuculline injection. The rise in other FFA was much smaller. Stearoyl- and arachidonoyl-DG were also accumulated. The drug alpha-methyl-p-tyrosine was found to (a) potentiate the bicuculline-stimulated release of cerebellar FFA, and (b) inhibit by 70% the production of stearoyl- and arachidonoyl-DG in the cerebrum and cerebellum. Basal production of FFA was stimulated by p-chlorophenylalanine, but the drug had no effect on the bicuculline-induced changes. Hydrolysis of phospholipids enriched in stearoyl-arachidonoyl groups, such as phosphatidylinositol of excitable membranes, may be stimulated during seizures.

Animals↗
PubMed1985

Hydrolysis of endogenous phospholipids by rat brain microsomes.

Phosphatidylcholine of rat brain microsomes was labeled in vivo by intracerebral injection of either [3H]oleic acid or [methyl-3H]choline chloride. These labeled microsomes served both as the enzyme source as well as a source of endogenously labeled substrate. Phospholipase D (PLD) activity was detected with these particles only in the presence of exogenous oleate, its activator. Ca2+ and the ionophore A 23187 inhibit PLD activity of oleate-labeled microsomes. In oleate-labeled particles, besides phosphatidic acid the product of PLD action radioactivity was also detected in diglyceride as a result of resident phosphatidate phosphohydrolase, which hydrolyzed the phosphatidic acid. The phosphatidate phosphohydrolase could not be completely inhibited by KF and propranolol. The release of endogenous fatty acids from labeled phospholipid by a mellitin-stimulated phospholipase A2 also present in these particulates produced minimal stimulation of endogenous PLD. Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) are hydrolyzed by 50% in the presence of mellitin and 90% of the radioactivity was found in the lyso-compounds. Mellitin and oleate together reduced the radioactivity found in lyso-PC and increased that in lyso-PE.

Animals↗
PubMed1985

Catabolism of myo-inositol to precursors utilized for de novo glycerolipid biosynthesis.

Systemic injection of [2-3H]myo-inositol into frogs resulted in the incorporation of more than half of the label into glycerolipid classes other than phosphoinositides in retinal rod outer segment membranes. Following methanolysis and differential extraction of isolated lipid classes, radioactivity was recovered primarily in the aqueous phase. After phospholipase C hydrolysis of the total membrane lipids, 97% of the radioactivity was extractable with organic solvents, and 70% of the label in lipids was in 1,2-diglycerides. These results indicate that the label was incorporated primarily into the glyceryl moiety of the membrane glycerolipids. Intraocular injection of frog eyes or in vitro incubation of frog retinas with [2-3H]myo-inositol resulted in the incorporation of radioactivity almost exclusively into phosphoinositides in rod outer segment membranes. Incubation of retinas with [U-14C]glucuronic acid did not result in the formation of labeled retinal lipids. These results suggest that myo-inositol can be catabolized systemically to precursors utilized for glycerolipid biosynthesis in the retina.

Animals↗
PubMed1989

Bradykinin stimulates phosphoinositide hydrolysis and mobilization of arachidonic acid in dorsal root ganglion neurons.

Cultures of fetal rat dorsal root ganglion neurons (7 days in culture) were prelabeled with myo-[3H]inositol or [3H]arachidonic acid for 24 h and stimulated with 10 microM bradykinin for time intervals of 5-300 s. The incubation was terminated by addition of 5% perchloric acid to extract inositol phosphates or organic solvent to extract lipids. Inositol phosphates were resolved by anion-exchange HPLC; lipids were resolved by TLC. Bradykinin stimulation resulted in a 10-fold increased accumulation of inositol 1,4,5-trisphosphate (IP3) and inositol bisphosphate (IP2) (fivefold) by 5 s. The increase in IP3 was transient (half maximal by 1 min), whereas stimulated IP2 levels were sustained for several minutes. Even longer term increases were observed in inositol monophosphate. Stimulation also resulted in a threefold increase in arachidonic acid which was preceded by transient increases in diacylglycerol (twofold) and arachidonoyl-monoacylglycerol (threefold). The temporal lag in the accumulation of arachidonic acid with respect to diglyceride and monoglyceride suggested the involvement of di- and monoglyceride lipases in arachidonic acid mobilization. A role for phospholipase A2 is also possible, because pretreatment of cultures with quinacrine partially blocked arachidonic acid release. Bradykinin-stimulated arachidonic acid release was decreased in the presence of calcium channel blockers nifedipine or verapamil (50 microM), or EDTA (2.5 mM). The role of calcium was verified further in that accumulation of phosphatidic acid, diacylglycerol, and arachidonic acid was maximally stimulated by treatment with the calcium ionophore A23187 (20 microM).

Animals↗
PubMedDate not supplied

Detailed analyses of individual neutral lipid classes of Pneumocystis.

Individual neutral lipid classes of Pneumocystis carinii carinii were isolated and purified by thin-layer chromatography. The fatty acids in steryl esters, triglycerides, free fatty acids, diglycerides, and monoglycerides were quantified by gas-liquid chromatography. The fatty acid compositions of these lipids were similar to those of the neutral lipid classes in whole rat lung controls, unlike comparable studies of phospholipid classes. The free fatty alcohols of rat lung controls and P. carinii were also identified and quantified; only saturated fatty alcohols were detected.

Animals↗
PubMed1998

Lipoarabinomannan induced cytotoxic effects in human mononuclear cells.

Mycobacteria produce large quantities of lipoarabinomannan, a cell wall associated glycolipid, which confers virulence in many of the disease causing members of the genus. We studied the lipoarabinomannan induced altered signaling mechanism in human peripheral mononuclear cells. Lipoarabinomannan isolated from Mycobacterium smegmatis (a non-pathogenic species) at concentrations of 2, 5 and 10 microg ml(-1) was used for the study. It was found that protein kinase C activity of human mononuclear cells was significantly inhibited by lipoarabinomannan at these concentrations in a dose dependent manner. Calcium, phosphatidyl serine and diglyceride dependent phosphorylation of endogenous proteins (mainly 90-, 80-, 66-, 38-, 36- and 34-kDa proteins) were also inhibited. Potentially cytotoxic superoxide anions generated by peripheral blood mononuclear cells were scavenged by lipoarabinomannan. It was also observed that incubation of peripheral blood mononuclear cells with lipoarabinomannan at concentrations of 5 and 10 microg ml(-1) for 6 h directed the cells towards apoptotic cell death, confirmed by DNA degradation analysis, microscopic observation of Wright-Giemsa as well as DAPI stained nuclei. These results clearly demonstrate that lipoarabinomannan from M. smegmatis may exert its cytotoxic activity via inhibition of protein kinase C, a key signaling molecule inside the mononuclear cells, which ultimately affects the phosphorylation of various proteins imperative for cellular defence and survival.

Adult↗
PubMed1977

Role of feeding on lipase activity in gastric contents.

Lipase activity was recorded in gastric contents collected from healthy term and preterm neonates. In contrast to pancreatic lipase activity this lipase activity was higher at pH 5.5 than at pH 8.0 and it was more resistent to acid inactivation. Lipase activity was found in gastric contents from all infants who were regularly fed, but was not present in gastric contents from some infants when collected before regular feeding was established. During test meals lipase activity in gastric contents increased considerably in all infants studied. During such a test meal there was a progressive relative decrease in triglycerides whilst diglycerides showed a relative increase suggesting an active lipolytic process in the stomach. An assay procedure for determination of lipase activity in gastric contents is also described.

Diglycerides↗
PubMed1975

Effects of lead on the lipid composition of Micrococcus luteus cells.

Micrococcus luteus cells cultivated in medium containing lead salts exhibited a sequence of changes in the quantity of total cellular lipids with essentially no changes from normal cellular yields. The lipid composition of cells cultivated one to four times was moderately decreased (phase I) whereas that of cells cultivated five to six times was reduced by as much as 50% (phase II). Cells cultivated more than six times in lead-containing media had progressively greater quantities of lipid (phase III) approaching that found in control cells. These cells with reestablished lipid contents showed no further effects from more prolonged exposure to lead salts. Chromatographic studies of total lipids of cells of each lipid phase revealed relatively complete lipid compositions. These results indicated that lead is apparently affecting a common biochemical parameter in the biosynthesis of lipids of lipid phase II cells. Changes in the relative quantities of individual components were observed in both the nonpolar and polar lipids in each lipid phase. The most notable changes were the decrease in aliphatic hydrocarbons with concomitant increases in the diglycerides and components identified as a complex family of ketones. Microscopy examinations of control and lead-treated cells revealed electron dense inclusion bodies in membrane fragments in only lead-treated cells.

Autoradiography↗
PubMed1974

Preliminary analysis of lipids and fatty acids of green bacteria and Chloroflexus aurantiacus.

The complex lipids and fatty acids of the seven type species of green bacteria and three strains of Chloroflexus aurantiacus were analyzed. The green bacteria contained lipids that behaved as cardiolipin and phosphatidylglycerol on thin-layer chromatography. They did not contain phosphatidylethanolamine or phosphatidylserine. Similarly, Chloroflexus contained lipids that behaved as phosphatidylglycerol and phosphatidylinositol on thin-layer chromatography and did not contain phosphatidylethanolamine or phosphatidylserine. The green bacteria contained glycolipids I and II of Constantopoulos and Bloch (monogalactosyldiglyceride and a galactose- and rhamnose-containing diglyceride). Chloroflexus exhibited galactose-containing glycolipids that behaved identically with the mono- and digalactosyldiglycerides of spinach on thin-layer chromatography, and each contained galactose as well as at least one other sugar. The fatty acids of both groups of bacteria consisted entirely of saturated and monounsaturated fatty acids. In the green bacteria, myristic, palmitic, and hexadecenoic acids predominated. In Chloroflexus, palmitic, stearic, and oleic acids predominated. The positions of the double bonds in the monounsaturated fatty acids of Chloroflexus indicated synthesis by the anaerobic pathway. The lipid analyses suggest a close relationship between the green bacteria and Chloroflexus and further suggest that these groups of photosynthetic bacteria are more closely related to the blue-green algae than are the purple bacteria.

Anaerobiosis↗
PubMed1975

Properties of a membrane-bound cardiolipin synthetase from Lactobacillus plantarum.

Cardiolipin (CL) synthetase of Lactobacillus plantarum 17-5 catalyzed the stoichiometric conversion of 2 mol of phosphatidylglycerol to 1 mol of CL. The enzyme activity was linear with time for 30 min at 37 C and with protein concentration between 20 and 200 mug of protein per ml. The enzyme was membrane associated, had a pH optimum of 5.1 in phosphate buffer, and was not stimulated by Mg2+, and the activity was not affected by the addition of ethylenediaminetetraacetic acid, cytidine diphosphate diglyceride, or cytidine triphosphate. The reaction was inhibited about 95% by Triton X-100 (0.5% final concentration) and by CL, the end product of the reaction. The activity of this enzyme was studied as a function of growth. The CL synthetase specific activity was highest during the early and midexponential growth phases, as was the cellular content of CL. The results demonstrate a correlation between enzyme-specific activity and lipid content of the cells.

Cardiolipins↗
PubMed1976

Lipid composition and lipid metabolism of Spiroplasma citri.

In a horse serum-based medium containing a full complement of fatty acids, cells of Spiroplasma citri were seen to preferentially incorporate palmitic acid. In the same medium, which had a steryl ester-to-sterol ratio of 3.64, a steryl ester-to-sterol ratio of 0.23 was seen in the cells, cholesterol being preferentially incorporated over cholesteryl ester. Like most other mycoplasmas, S. citri was shown to be unable to synthesize fatty acids or esterify cholesterol. The neutral lipids of S. citri grown in a medium containing horse serum consisted of free cholesterol, cholesteryl ester, free fatty acids, triglycerides and diglycerides. All polar lipids were phospholipids, with no glycolipids detected. These phospholipids, which are characteristic of many mycoplasmas, are phosphatidyl glycerol, diphosphatidyl glycerol, and their lyso derivatives. Sphingomyelin was also incorporated when cells were grown on horse serum. A sterol requirement for the growth of S. citri was confirmed using a serum-free medium supplemented with bovine serum albumin, palmitic acid, and various concentrations of sterols dissolved in Tween 80. The addition of palmitic acid stimulated growth but was not essential for growth. S citri was shown to grow best on cholesterol and beta-sitosterol and was able to grow on stigmasterol and ergosterol to a lesser degree. No growth was obtained using mevalonate, deoxycholate, or taurodeoxycholate as an alternative to sterol. S. citri was also able to grow when palmitic acid was replaced with oleic acid, linoleic acid, or linolenic acid. Alterations in the lipid composition of the growth medium and hence in the lipid composition of S. citri induced changes in the characteristic helical morphology of the cells, concurrent with loss of cell viability. Culture, age, and pH were also factors in determining cell morphology and viability.

Cholesterol↗
PubMed1976

Lipids of Branhamella catarrhalis and Neisseria gonorrhoeae.

Three strains of Branhamella catarrhalis and three strains of Neisseria gonorrhoeae were analyzed with regard to their phospholipid and neutral lipid composition. B. catarrhalis (ATCC 23246) contained 5.12 +/- 0.34% lipid, determined gravimetrically, compared to 8.56 +/- 0.15% and 9.73 +/- 0.06% for two strains of N. gonorrhoeae. Cardiolipin, phosphatidylglycerol, and phosphatidyl-ethanolamine were identified in extracts of both species. In addition, B. catarrhalis contained small amounts of phosphatidylcholine, and N. gonorrhoeae contained small amounts of lyso-phosphatidylethanolamine, which accumulated with autolysis accompanying late cell culture growth. The kinetics of change of relative amounts of phospholipids in both species were measured and found to differ substantially. Neutral lipid accounted for 30.4% of the total lipid of B. catarrhalis (ATCC 23246) and 7.6% of the total lipid of N. gonorrhoeae NYH 002. Hydrocarbons, triglycerides, free fatty acids, coenzyme Q, diglycerides, and free hydroxy fatty acids were identified in the neutral lipid fraction of both species. The three strains of N. gonorrhoeae, sensitive, intermediate, and resistant to penicillin, exhibited no significant difference in the composition or metabolism of phospholipid.

Anti-Bacterial Agents↗