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PubMed1990

Effects of lipids on thermophilic anaerobic digestion and reduction of lipid inhibition upon addition of bentonite.

The effect of bentonite-bound oil on thermophilic anaerobic digestion of cattle manure was investigated. In digestor experiments, addition of oil was found to be inhibitory during start-up and the inhibitory effect was less pronounced when the oil was added in the form of bentonite-bound oil compared to when the oil was added alone. After adaptation of the digestors, very rapid degradation of oil was observed and more than 80% of the oil was degraded within a few hours after daily feeding. In batch experiments, glyceride trioleate was found to be inhibitory to thermophilic anaerobic digestion when the concentrations were higher than 2.0 g/l. However, addition of bentonite (a clay mineral) at concentrations of 0.15% and 0.45% was found to partly overcome this inhibition. Addition of calcium chloride in concentration of 3 mM (0.033% w/v) showed a similar positive effect on the utilization of oil, but the effect was lower than with bentonite.

Anaerobiosis↗
PubMed1977

Isolation of fat cell precursors from adult rat adipose tissue.

The possible existence of adipocyte precursors in adult rat adipose tissue was investigated. Cells were isolated from the stromal fraction of adipose tissue and were grown in culture. Skin fibroblasts were used as controls. The stromal fraction cells were initially fusiform and proliferated; in culture, they accumulated lipid inclusions, became rounder and acquired an eccentric nucleus. In contrast, the skin fibroblasts from the same rat grown under identical culture conditions, did not exhibit any appreciable lipid accumulation. The doubling time for both the stromal fraction cells and skin fibroblasts was 40-60 h. At confluency, the stromal fraction cells contained 5-7 times more glyceride-glycerol than skin fibroblasts. Thus, adipose tissue of adult rats contains cells with the potential to proliferate and acquire morphological characteristics similar to those of adipocytes.

Adipose Tissue↗
PubMed1988

In vitro alterations of L-asparaginase activity of Tetrahymena pyriformis by lipids.

A membrane-bound L-asparaginase (EC 3.5.1.1) of Tetrahymena pyriformis was purified to homogeneity. The purified enzyme is a lipoprotein, since it is inactivated by phospholipase C and its activity is restored by the addition of naturally occurring lipids, such as phosphatidylcholine, triolein and oleyl acetate. The relative effectiveness of a variety of phospholipids, free saturated and unsaturated fatty acids, or neutral lipids, such as esters of fatty acids and glycerides, with respect to the activation of purified L-asparaginase is compared. Enzyme activity is reconstituted in the presence of lipids and evidence for the formation of an enzyme-phospholipid complex is presented. The data of this report suggest that L-asparaginase may have a requirement for lipids that reconstitute a physiological hydrophobic environment, similar to the one existing in vivo.

Animals↗
PubMed1984

Post-translational modification and processing of outer membrane prolipoproteins in Escherichia coli.

This mini review is primarily concerned with the biosynthesis of the major outer membrane lipoprotein of Escherichia coli. The lipoprotein is composed of fifty-eight amino acid residues, one glyceride residue and one acyl residue being at the amino terminal cysteine residue. About one-third of the lipoprotein is covalently bound to the underlying peptidoglycan layer and plays an important role in the assembly of the outer membrane on the peptidoglycan layer. The lipoprotein is first synthesized on ribosomes as a precursor form having twenty extra amino acid residues (signal peptide) at the amino terminus. During secretion through the cytoplasmic membrane, the modification at the cysteine residue that is to be the amino terminus of the mature lipoprotein and cleavage of the signal peptide take place successively. These events are then followed by N-acetylation of the terminal cysteine residue, translocation to the outer membrane, and covalent binding to the peptidoglycan layer of the lipoprotein. Digestion of the cleaved signal peptide also takes place upon cleavage of the signal peptide. In this review these chemical and topographical events are discussed step by step especially in relation to the process of protein secretion across the cytoplasmic membrane.

Acylation↗
PubMed1980

Insulin binding and hexose transport in rat adipocytes. Relation to cell size.

Insulin binding, initial velocity of [14C]methylglucose transport, uptake of [14C]deoxyglucose and conversion of [U-14C]glucose to CO2, glyceride-glycerol and fatty acids were measured at 37 degrees C in adipocytes from rats of different weights (135-450 g) and therefore with different mean cell volumes (53-389 pl). Insulin binding per cell increased with increasing cell size and binding was 2.3 times higher in the largest cells than in the smallest cells with tracer alone. The difference was largely accounted for by an increase in the apparent affinity. Influx of methylglucose per cell increased with increasing cell size in the absence of insulin and remained constant as a function of cell size in its presence. The effect of insulin ranged from 11 fold in small cells to 3.5 fold in large cells. The rat of conversion of [U-14C]glucose to CO2 and lipids was about half of the rate of methylglucose transport under all conditions. In contrast, the uptake of deoxyglucose in insulin-stimulated cells decreased markedly with increasing cell size. Increasing cell size caused a small decrease in sensitivity which could be explained by a smaller amont of insulin bound per unit surface area. The results show that increasing cell size/animal weight causes changes in insulin binding which may explain changes in sensitivity. In addition, the hexose transport system is modified in a way which is not explained by changes in insulin binding. Finally, changes in deoxyglucose uptake with cell size do not parallel changes in methylglucose transport.

Adipose Tissue↗
PubMed1988

Influence of oral isotretinoin treatment on the composition of comedonal lipids. Implications for comedogenesis in acne vulgaris.

One of the primary events in the pathogenesis of acne vulgaris is abnormal follicular keratinization. Since oral isotretinoin therapy reduces follicular hyperkeratinization in acne, our study has been designed to determine whether epidermal lipid composition of the epithelium of sebaceous follicles is affected by isotretinoin treatment. Noninflamed early comedones obtained from ten patients with nodulocystic acne before and after the 6th week of isotretinoin therapy (mean daily dose 0.7 mg/kg b. wt.) were used as probes of the hyperkeratinizing follicular epithelium. Comedonal lipids were analyzed by high-performance thin-layer chromatography. Oral isotretinoin caused a decrease of the comedonal glyceride fraction by 36% (P less than 0.01), whereas free sterols and total ceramides increased by 34% (P less than 0.10) and 19%, respectively. The changes of comedonal lipids were associated with a significant elevation of the free sterols/cholesterol sulfate ratio of 86% from pretreatment levels (P less than 0.05). The isotretinoin-induced changes of the comedonal lipid composition in direction to a pattern of epidermal lipids of normal desquamating stratum corneum are discussed as a possible comedolytic mechanism of oral isotretinoin treatment.

Acne Vulgaris↗
PubMed1984

Amino acid and lipid composition of refringent granules from the ameboid sperm of Ascaris suum (Nematoda).

Transformation of the spermatozoon of Ascaris suum from a spheroidal to an ameboid cell is associated with the formation of a motile pseudopodium and coalescence of the intracellular refringent granules. The pseudopodia of the ameboid spermatozoa contain filaments organized into dense patches, bundles, web-like or lace-like networks, as observed by electron microscopy. The morphology and chemistry of the refringent granules were investigated in subcellular fractions enriched for these structures. Isolated refringent granules were heterogeneous in size measuring from 0.5 X 0.6 to 2.3 X 3.5 microns. Each granule is surrounded by a 110 A thick layer. During fusion, the surfaces of the refringent granules form small extensions resembling micropodia. The process of fusion occurs at many sites on a given granule and simultaneous fusion of several granules was commonly observed. Amino acid analyses of the refringent granule proteins (RGP's) indicated: they are rich in aspartic acid or asparagine (48%), leucine (10%), serine (19%) and aromatic amino acids (11%). Gas-liquid chromatographic analyses of alditol acetate derivatives of monosaccharides released by mild acid hydrolysis showed the predominant sugars to be glucose (7.3 micrograms/mg protein), galactose (9.2 micrograms/mg) and N-acetylglucosamine (5.5 micrograms/mg). Lipid analyses indicated a complex mixture of glycerides, ascarosides and waxes, together with a major component that resembled free fatty acid in mobility on TLC.

Amino Acids↗
PubMed1982

Hydrolysis of vegetable oils and triglycerides by thermotolerant and zoopathogenic species of Aspergillus from Nigerian palm produce.

The ability of Aspergillus fumigatus Fres. and Aspergillus nidulans (Eidam) Wint obtained from Nigerian palm produce to degrade vegetable oils and triglycerides and the production and activity of their extracellular lipases were studied. Both species readily hydrolysed palm oil and palm kernel oil among others liberating free fatty acids in the process. Good growth with mycelia production of both fungi were also recorded on the triglycerides used as sources of carbon at 37 degrees C with the best results obtained on palmitic and oleic acids, the predominant fatty acids in palm oil. Extracellular lipases were detected in the culture filtrates of both fungi within 48 h of incubation on an oat-meal chaff medium at 37 degrees C. Peak enzyme production occurred within the 10-day incubation period. The lipases of both fungal species were most active at a pH of 5.6 and a temperature of 45 degrees C. The best glyceride for assaying the lipase activities of these fungi was trihexanoin while palm oil was a better vegetable oil than the conventional groundnut oil used for the same purpose. Because of the zoopathogenic nature of these fungi, attention is drawn to the potential health risks which their presence on the palm products where they were obtained pose to the consumers.

Agriculture↗
PubMed1990

Celiptium-induced nephrotoxicity and lipid peroxidation in rat renal cortex.

The antitumor drug celiptium, or N2-methyl-9-hydroxyellipticinium (NMHE), is an ellipticine derivative used in the treatment of breast cancer. Celiptium-induced dose-dependent renal toxicity in rats is characterized by tubular necrosis, tubulo-interstitial lesions and lipid overload in proximal tubular cells. Since biooxidative activation of celiptium occurs in kidney via highly electrophilic intermediates, we studied the effects of celiptium on rat renal cortex lipids in the context of lipid peroxidation damage. Female Wistar rats were injected with a single i.v. dose of 20 mg/kg celiptium and were killed on day 2, 4 or 8. Histochemical analysis of kidney sections detected Oil Red O (ORO)-positive deposits, whereas the same sections studied using Holczinger's copper rubeanic acid method showed free fatty acid (FFA) granules in renal tubular cells of celiptium-treated rats. Electron microscopy revealed large fatty droplets in proximal tubular cells. As creatinine clearance decreased on days 4 and 8, celiptium induced a significant increase in renal cortex FFA levels (6-fold increase over pretreatment values on day 8), whereas total glycerides increased 1.5 times. A 15% decrease in total phospholipids (PL) and a 50% decline in the mass of phosphatidylethanolamine (PE) were detected by lipid phosphorus assay. A 1.2-fold decrease in the unsaturation index of total PL was noted, with a significant decline in arachidonic acid (20:4). A 15% decrease in arachidonic content was observed in the fatty acid composition of PE. Analysis of the fatty acid composition of neutral lipids showed changes only in the FFA class. A great proportion of oleic (18:1) and linoleic (18:2) acids was found. Iodometric titration and thiobarbituric acid (TBA) reactivity detected respectively significant amounts of lipid hydroperoxides and TBA-reactive material in renal cortex lipid extracts on days 2, 4 and 8. The lipid-peroxidation process appeared to be involved in the pathogenesis of celiptium nephrotoxicity.

Animals↗
PubMed1994

Intestinal lipid metabolism in suckling rats infected with Giardia duodenalis.

We carried out a quantitative and qualitative analysis of intestinal digestion of neutral lipids in suckling rats infected with Giardia duodenalis. Total lipids were measured after extraction from the contents of the stomach, proximal and distal small bowel, caecum and colon. Amounts gradually fell from the stomach to the colon and were identical in infected animals and controls, although high values were occasionally found in the caecum of infected rats. Relative glyceride quantities were determined by means of high-performance thin-layer chromatography. Triglycerides were absent from the distal small bowel, and only free fatty acids and cholesterol were present in the caecum, reflecting normal digestion of neutral lipids in infected suckling rats. Our results suggest that G. duodenalis does not impair intestinal fat digestion in suckling rats.

Animals↗
PubMed1978

Preventive effect of gliclazide on experimental atherosclerosis in rabbits.

Administration of a hypoglycaemic sulphonamide, gliclazide, at 10 mg/kg/day p.o. to rabbits for 60 days did not affect the development of plasma lipid disturbances induced by a high cholesterol diet. The accumulation of cholesterol in the liver was significantly reduced by up to 34% when compared with animals on the high cholesterol diet. The high concentrations of glycerides and fatty acids in the aorta were significantly decreased towards normal values and histology showed that the gliclazide strongly inhibited the development of aortic and particularly coronary lesions induced by the atherogenic diet. A normal appearance of coronary arteries was noted in more than 50% of cases.

Animals↗
PubMedDate not supplied

Glycolysis and glucose oxidation in the rat heart under nonrecirculating perfusion conditions.

Isolated rat hearts were perfused according to Langendorff and as a working heart preparation with glucose as the only exogenous substrate under nonrecirculating conditions to avoid accumulation of heart metabolites and, thereby, changes in the composition of the perfusion medium. In the absence of insulin or at low work, oxidation of endogenous substrates as glycogen is of importance for myocardial energy metabolism. Accordingly, about 1/3 of the glucose oxidized by the heart was derived from myocardial glycogen. Lipolysis of endogenous triglycerides and oxidation of the fatty acids produced were, however, low in normal rat hearts. By contrast, in the presence of insulin or at high work load endogenous substrates play a minor role for energy provision. About 80% of the total oxygen consumption could be attributed to the oxidation of exogenous glucose. Furthermore, insulin exerted its major effect in accelerating glucose uptake and glycolysis, but had little influence on PDH-activity. Insulin increased lipolysis in control hearts, however, changes in the endogenous triglycerides were less than valves calculated from the rate of lipolysis. Thus, glycerol release can be taken as a measure for lipolysis, but not as a measure for fatty acid oxidation, since the produced fatty acids were partly reesterified to glycerides. On the basis of the metabolic data obtained, the oxygen and energy balance was calculated. We conclude that a sufficient energy provision is only warranted if the rat heart is perfused either in the presence of insulin or at higher--more physiological--work load.

Adenosine Triphosphate↗
PubMed1975

Triglyceride composition of Sapindus mukorossi seed oil.

The fatty acid composition of Sapindus mukorossi seed oil was determined by spectrophotometry, urea complexation, and gas liquid chromatography (GLC). The percentages of individual acids were found to be: palmitic, 4.0; stearic, 0.2; arachidic, 4.4; oleic 62.8; linoleic, 4.6; linolenic, 1.6; and eicosenoic, 22.4. Triglyceride composition was calculated from the fatty acid compositions of the native oil and of the monoglycerides produced from it by pancreatic lipase hydrolysis. The oil is composed of 0.1, 2.1, 22.0, and 75.8% trisaturated, monounsaturated disaturatd, diunsaturated monosaturated, and triunsaturated glycerides, respectively. The special characteristic of the Sapindus mukorossi seed oil is its content of 26.3 and 26.7% triolein and eicoseno-di-oleins, respectively.

Chromatography, Gas↗
PubMed1976

Effect of dietary polyunsaturated pork on plasma lipids and sterol excretion in man.

Pork, enriched in linoleic acid content, was compared iwth conventional pork in the diet of three human subjects with respect to the plasma cholesterol concentration and the excretion in feces of neutral sterols and bile acids. Since the fatty acids in pork glyceride have an unusual positional distribution, the redistribution that might occur during the absorption and disposition of a fat meal was also studied. The plasma cholesterol was lower with polyunsaturated pork, the difference, 14 mg/100 ml plasma, being of the order expected from the change in polyunsaturated to saturated fatty acid ratio. On average, the excretion of neutral sterols was 57% greater with polyunsaturated than with conventional pork in all three subjects, and in this respect the results resembled the findings with polyunsaturated ruminant fats. During the absorption of pork fat, the high proportion of palmitate in the 2 position of lard triglyceride served as a useful marker, since human triglyceride carries mainly unsaturated fatty acids in that position. There were stepwise changes in the fatty acid composition at the 2 position of triglyceride as the fat was absorbed, transported through, and cleared from plasma, the palmitate being gradually replaced by oleate and linoleate. By contrast, the total fatty acid profile in the triglyceride changed relatively little, implying selective reacylation with palmitate at the 1 and/or 3 position. During the clearing of dietary triglyceride, the porcine triglyceride was thus converted to the form occuring in humans.

Adult↗
PubMed1977

Heart mitochondrial metabolism after feeding herring oil to rats and monkeys.

Heart mitochondrial oxidation of palmityl CoA and pyruvic acid was studied in rats and in the monkey Macaca fascicularis to determine the effects of feeding partially hydrogenated herring oil. Herring oil glycerides contain cetoleic acid (cis-11-docosenoic) which could have a similar effect to erucic acid (cis-13-docosenoic) in causing a rat cardiomyopathy. The initial rat heart mitochondrial response to dietary cetoleic acid (67% cis, 33% trans) was an in vitro decrease in palmityl CoA oxidation. Pronlonged feeding of cetoleic acid mixture was associated with a significant metabolic adaptation, increasing pyruvate and palmityl CoA oxidation above control levels. In vitro addition of cetoleyl CoA (pure cis isomer) stimulated pyruvate dehydrogenase activity, a possible response to decreased B-oxidation. There was no significant adaptive change in pyruvate or palmityl CoA use in monkeys after prolonged feeding of partially hydrogenated herring oil. Cetoleyl CoA was a good substrate for monkey heart carnitine acyl transferase even in the presence of palmityl CoA. These observations suggest that C22 fatty acids may be metabolized more rapidly in monkey heart than in rat heart. Metabolic differences argue against using the rat as an experimental model for studying possible cardiotoxic effects of docosenoic acids in primates.

Animals↗
PubMed1977

Lipids of cultured hepatoma cells: VIII. Utilization of D-[1-14C] glucose for lipid biosynthesis.

Minimal deviation hepatoma 7288C cells (HTC) were incubated in serum-supplemented and serum-free Swim's 77 medium in the presence of D-[1-14C] glucose for 1, 2, 4, 8, 12 and 24 hr. Glucose oxidation to CO2, incorporation into total cell mass, and incorporation into cell and medium lipids were determined. The percentage distribution of total cell lipid radioactivity in individual neutral and polar lipid classes was followed as a function of time. Degradation studies of individual lipid classes were performed to ascertain the percentage of radioactivity in acyl and glycerol moieties. The percentage of D-[1-14C] glucose oxidized to 14CO2, incorporated into cell matter and cell lipids was elevated in cells incubated in serum-free medium as opposed to serum-supplemented medium. The percentage distribution of total cell lipid radioactivity into individual neutral lipid classes from both serum-free and serum-supplemented cultures was as follows: sterols greater than triglycerides greater than free fatty acids greater than sterol esters. The percentage distribution of total cell lipid radioactivity into individual polar lipid classes of serum-supplemented cultures was as follows: phosphatidylcholine greater than phosphatidylinositol greater than sphingomyelin greater than phosphatidylethanolamine greater than phosphatidylserine. The distribution of glucose radiolabel into individual polar lipid classes of serum-free HTC cells was different from their serum-supplemented counterparts: sphingomyelin greater than phosphatidylcholine greater than phosphatidylinositol greater than phosphatidylethanolamine greater than phosphatidylserine. Glycerol from glyceride classes contained a higher percentage of radioactivity than the acyl moieties, with this percentage significantly elevated in serum-free cultures. The data indicate that, although glucose is a substrate for HTC cell lipids, other precursors present in the culture system also contribute to the lipid constituency of this hepatoma cell line.

Blood↗
PubMed1977

Serum and liver lipid responses to 3-hydroxy-3-methylglutaric acid in rats on different carbohydrate diets.

Groups of male adult albino rats were administered 3-hydroxy-3-methylglutaric acid (HMG) intraperitoneally along with six diets differing only in the type of carbohydrate used. Groups not treated with HMG served as controls. HMG showed a significant cholesterol- and tri-glyceride-lowering effect in the whole serum, serum beta-lipoproteins, and liver of animals on all types of dietary carbohydrates. The effect was more marked in glucose, fructose, sucrose, and lactose. The phospholipid levels in whole serum, serum beta-lipoproteins, as well as in liver were also significantly lowered on all types of carbohydrates except dextrin and starch fed animals, where it had no effect on liver levels. The lipid-lowering effect of HMG seems to be independent of the type of carbohydrate in diet.

Animals↗
PubMed1978

Triglyceride synthesis from dihydroxyacetone phosphate and palmitate by microsomes from mammary glands of lactating mice.

Both di- and triglycerides were synthesized when microsomes isolated from mammary glands of lactating mice were incubated with dihydroxyacetone phosphate (DHAP), 1(-14)C)palmitate, ATP, CoASH, GSH, KF, MgC12, and NADPH. When NADH replaced NADPH, glyceride synthesis was very low. In the absence of either NADPH or NADH, DHAP was acylated to palmityl-DHAP. Since microsomes do not have glycerol 3-phosphate NAD:oxidoreductase activity , we inferred that glycerol 3-phosphate (GP) is not an intermediate in triglyceride biosynthesis from DHAP. This reductase, present in the cytosol, was active only with NADH. With the same concentration of either GP or DHAP, microsomes yielded essentially similar amounts of di- and triglycerides. Mitochondria, while capable of synthesizing palmityl-DHAP, did not produce di- and triglycerides.

Animals↗