Showing papers in "Lipids in 1972"

An enzymatic protective mechanism against lipid peroxidation damage to lungs of ozone-exposed rats.

Abstract: The effects of whole animal exposure to ozone and of dietary α-tocopherol on the occurrence in rat lung of lipid peroxidation and alteration of the activity of enzymes important in detoxification of lipid peroxides were studied. Exposure to 0.7 and 0.8 ppm ozone continuously for 5 and 7 days, respectively, significantly elevated the concentration of TBA reactants, primarily malonaldehyde, produced by lipid peroxidation, as well as the activities of glutathione (GSH) peroxidase, GSH reductase and glucose-6-phosphate (G-6-P) dehydrogenase. As a logarithmic function of dietary α-tocopherol (0, 10.5, 45, 150 and 1500 mg/kg), the increase in formation of malonaldehyde and the increase in activities of GSH peroxidase and G-6-P dehydrogenase were partially inhibited. The activity of GSH reductase was not affected by dietary α-tocopherol. The concentration of malonaldehyde and the activity of GSH peroxidase in lung were linearly correlated (p<0.001). This study confirmed the occurrence of lipid peroxidation in the lung during ozone exposure and revealed an enzymatic mechanism against damage. An apparent compensation mechanism is that with increased lipid peroxides there is increased activity of GSH peroxidase, which in turn increases lipid peroxide catabolism. The increased activities of GSH reductase and G-6-P dehydrogenase also function in the protective chain by providing increased levels of GSH and NADPH, respectively.

Triton-induced hyperlipidemia in rats as an animal model for screening hypolipidemic drugs

Abstract: We describe a screening test for hypolipidemic agents in which compounds are administered orally to fasted rats after a single intravenous injection of 225 mg Triton WR-1339/kg and serum cholesterol and triglycerides are measured 43 hr post-Triton. Conditions for the screen were established by studying interrelationships between serum cholesterol, triglycerides and Triton levels during the post-Triton period and the effects of Triton dose, route of administration and fasting on serum lipid levels and drug hypocholesterolemic activity. The test detects compounds which inhibit lipid biosynthesis or stimulate lipid catabolism. Several drugs with different mechanisms of action which are hypolipidemic in man, including nicotinic acid,D-thyroxine, triparanol, nafoxidine HCl and clofibrate are active in this system. Results with standard hypolipidemic agents are reproducible and conform well to performance levels of the screen predicted from statistical analysis.

Stearyl CoA as a precursor of oleic acid and glycerolipids in mammary microsomes from lactating bovine: possible regulatory step in milk triglyceride synthesis.

Abstract: The stearyl desaturase of lactating bovine mammary tissue is located in the microsomes and requires activated fatty acid and NADH for activity. Other enzymes, acyl-transferase(s) and deacylase which apparently compete with the desaturase for substrate are also present. Both the substrate 1-14C-stearyl CoA and the oleic acid produced by desaturase are esterified into the various lipid classes. The oleic acid is preferentially acylated into positionsn-3 of the triglycerides andsn-2 of the phosphatidylcholine. Experimental conditions causing reduced desaturase activity depressed triglyceride synthesis, and stimulation of desaturation by NADH L−α GP, acidic pH, 5.6, was accompanied by increased incorporation of radioactive fatty acids into the triglycerides. These data indicated that desaturase and glyceride acyl transferase were located contiguously within the microsomal membranes. The possibility that desaturase activity might control triglyceride synthesis in vivo is discussed. It was observed that mammary tissue from nonlactating cows 1–2 weeks and 2 days prior to calving lacked or possessed very low stearyl desaturase activity.

Uptake of blood triglyceride by various tissues.

Abstract: Triglycerides are transported in the blood in chylomicrons and very low density lipoproteins. Electron microscopic studies indicate that these particles, which range in diameter from 0.03–0.6 μ, cannot cross the capillary endothelium in most tissues. There is now considerable evidence that the triglycerides are hydrolyzed to free fatty acids (FFA) during uptake and that this process is catalyzed by lipoprotein lipase. The enzyme is found in nearly all tissues that utilize circulating triglyceride, and the level of activity, in individual tissues, varies with nutritional and physiological states that affect triglyceride uptake, such as fasting, diabetes and pregnancy. Studies in perfused adipose tissue with doubly labeled chylomicrons showed that hydrolysis occurs outside of the blood stream. Two-thirds of the fatty acids are incorporated into tissue triglyceride and the rest are release as FFA, with glycerol, to the blood. Infusion of heparin causes immediate release of lipoprotein lipase activity to the blood and decreases the amount of chylomicron-triglyceride hydrolyzed by the tissue. Electron microscopic cytochemical studies showed that hydrolysis of blood glycerides by lipoprotein lipase in adipose tissue occurs within the capillary endothelial cells and in the subendothelial space near the pericytes, but not in the capillary lumen or near the fat cells. The results indicate that the fatty acids of chylomicrons cross the capillary endothelium as glycerides and FFA, within a membrane-bounded system, and cross the extravascular space to the fat cells as FFA.

The fatty acids of wax esters and sterol esters from vernix caseosa and from human skin surface lipid.

Abstract: Separation of sterol esters from wax esters in the lipids of vernix caseosa and adult human skin surface was accomplished by column chromatography on MgO. The fatty acids of the sterol esters and wax esters of both samples were separated into saturates and monoenes, and examined in detail by gas liquid chromatography (GLC). The saturated fatty acids of the wax esters of vernix caseosa and of adult human skin surface were remarkably similar. They ranged in chain length from at least C11 to C30, six skeletal types being present: straight even, straight odd, iso, anteiso, other monomethyl branched and dimethyl branched. A large number of patterns of monoenes were observed, each pattern consisting of desaturation of a specific chain at Δ6 or Δ9 plus its extension or degradation products. The mole per cent of the total Δ6 and Δ9 patterns of wax ester fatty acid monoenes of vernix caseosa were 87% and 12%, respectively, and 98% and 1%, respectively, for adult human skin surface lipid. The sterol ester fatty acids of vernix caseosa were much different from those of adult human skin surface: vernix caseosa saturates were largely branched and of lengths greater than C18, whereas the saturates of adult human surface lipid resembled the wax ester fatty acids. Of the vernix caseosa monoene patterns, the mole per cent was 30% Δ6 and 70% Δ9, whereas of the adult human skin surface sterol ester fatty acids 89% were Δ6 and 11% Δ9. Chain extension was particularly pronounced in the sterol ester fatty acid monoenes of vernix caseosa amounting to 7–8 C2 units in some cases. The fatty acids of the sterol esters of both vernix caseosa and adult human skin surface appear to be derived from the sebaceous gland and from the keratinizing epidermis, but those of the wax esters are from the sebaceous glands only.

2‐Alkylcyclobutanones from the radiolysis of triglycerides

Abstract: A cyclic compound was isolated from the radiolytic products of each of the simple triglycerides containing C6, C8, C10, C12, C14, C16 and C18 fatty acids. In each case the compound was identified as the 2-alkylcyclobutanone of the same carbon number as the precursor fatty acid. A mechanism is proposed for the production of these compounds which involves the formation of a six-membered ring intermediate, cyclization and cleavage at the acyl-oxy bond.

Effect of androgens on serum lipids and lipoproteins.

Abstract: The effects of androgens on lipid transport and metabolism have been reviewed. These effects are probably independent of the androgenic and anabolic activities of the androgens, although the molecular mechanism of action is still not known. Presumably the lowering by androgens of the concentrations of serum lipids and lipoproteins could be the consequence possibly of a primary, inhibitory effect on the synthesis of apolipoprotein A. In addition the role of increased lipolytic activities in plasma and of effects on intermediatry metabolism has been considered.

Cardiac lipids in rats and gerbils fed oils containing C 22 fatty acids.

Abstract: Docosenoic acid from rapeseed oil or herring oil in the diet of the young rat promoted an accumulation of cardiac lipid. The triglyceride fraction accounted for most of the deposited fat and contained a high concentration of the docosenoic acid. Liquid rapeseed oil, partially hydrogenated rapeseed oil or partially hydrogenated herring oil increased the amount of cardiac fatty acids at 1 week and led to the development of degenerative lesions at 16 weeks. Whale or seal oils low in C22 fatty acids produced little effect on the amount of lipids in the heart of rats or gerbils. The latter species receiving 20% rapeseed oil in the diet showed a peak in cardiac lipid deposition at 4 days with similar levels of total fatty acids to that of rats, but with a lower concentration of erucic acid. Oil fromLimnanthes douglasii and hydrogenated herring oil also increased the amount of cardiac fatty acids in gerbils. A high intake of docosenoic acid was common to the animals displaying the cardiac alterations.

Toxicity of fatty ozonides and peroxides

Abstract: Studies on the acute toxicity of the ozonides and hydroperoxides of methyl linoleate are reported High purity preparations of these compounds were injected intravenously or administered orally to adult male rats The lethal dose by iv injection of these compounds was virtually the same −007 mmol/100 g body wt No deaths were caused in a 24 hr period by single oral dosages of these compounds of ca 10-fold that causing death by the iv route The major effect of these compounds was on the lungs The lungs became enlarged from edema and accumulation of fluid, and the animals died of lung congestion and injury similar to the effects of ozone toxicity There was no destruction of vitamin E in the tissues of animals given lethal dosages of ozonides or peroxides intravenously, but significant changes occurred in fatty acid composition of the lipids of the serum and lung Arachidonic acid increased at the expense of linoleic and oleic acids in these tissues Only small amounts of peroxidic and TBA positive substances were detected in lung and serum, indicating that the injected ozonides and hydroperoxides were destroyed in the tissues

Effect of dietary linolenic acid and docosahexaenoic acid on growth and fatty acid composition of rainbow trout (Salmo gairdneri)

Abstract: Methyl linolenate 18∶3ω3 and docosahexaenoate 22∶6ω3 were incorporated in semipurified diets at several levels and fed to trout previously maintained on a fat-free diet. After 14 weeks, the weight gain and feed conversion of the fish on each diet were determined. The fatty acid composition of the lipid from each group of fish was analyzed by gas liquid chromatography. Both 18∶3ω3 and 22∶6ω3 fed at the 1% level supported maximum growth of the fish. The control group, which were fed no ω3 fatty acids, exhibited a shock syndrome, poor appetite and a very slow growth rate. Tissue fatty acid analysis revealed eicosatrienoic acid 20∶3ω9 accumulated in the phospholipid fraction of this group. The 20∶3ω9 level was lowered when either 18∶3ω3 or 22∶6ω3 was included in the diet. Analysis showed that the dietary 18∶3ω3 was rapidly converted by the fish into 22∶6ω3 with a high concentration in the phospholipid. However 22∶6ω3 fed to the fish remained unchanged and little or no retroconversion of this fatty acid was observed.

Lipid metabolism during cold-exposure and during cold-acclimation.

Abstract: The lipid-containing tissues are important in cold-exposure (exposure to cold of animals not previously living in the cold) and in cold-acclimation (the adaptive state achieved when animals have lived in the cold for several weeks); these are the white adipose tissue and the brown adipose tissue. The white adipose tissue serves as a store of readily mobilized substrate (free fatty acids [FFA]) for calorigenesis in other tissues during cold-exposure, principally for shivering thermogenesis in muscle. The mobilization of the sterol lipid is brought about through activation of the sympathetic nervous system by the cold stress. The brown adipose tissue has two functions in cold-exposure and in cold-adaptation, both quite distinct from the function of the white adipose tissue. These functions are heat production and the maintenance of the adaptationto cold. The triglycerides stored in the brown adipose tissue are mobilized as FFA, also via activation of the sympathetic nervous system, but the FFA are used primarily within the brown adipose tissue itself. The FFA are the agents which switch on the calorigenesis in the brown adipose tissue (via a poorly understood form of “loosening” of the coupling of oxidative phosphorylation); they also serve as the substrate for the calorigenesis. The heat-producing function of the brown adipose tissue occurs in both cold-exposed and in cold-acclimated animals; it is of greater importance in the latter because this tissue normally grows in response to cold. Much of the heat production in cold-acclimated animals (nonshivering thermogenesis) occurs outside the brown adipose tissue itself, most probably in the muscles, and the cold-acclimated animal differs from the cold-exposed animal in being able to switch on nonshivering thermogenesis via activation of the sympathetic nervous system. The maintenance of this adaptation for nonshivering thermogenesis in tissue other than the brown adipose tissue itself depends upon the brown adipose tissue. The adaptation disappears if the brown adipose tissue is removed; the adaptation does not develop if the normal proliferation of mitochondria in the growing brown adipose tissue is inhibited (with oxytetracycline) during acclimation of rats to cold. The mechanism by which the brown adipose tissue exerts this second function is at present unknown. An increased turnover of certain mitochondrial proteins occurs in those tissues (skeletal muscle and brown adipose tissue) in which nonshivering thermogenesis occurs in cold-acclimated rats; no change in turnover of mitochondrial proteins occurs in other tissues (liver and kidney). The relation of this alteration in mitochondrial proteins to the adaptation for nonshivering thermogenesis is at present unknown. However this first demonstration of a biochemical difference between skeletal muscle of cold-acclimated rats and skeletal muscle of warm-acclimated rats opens up a new approach to the study of the nature of both the adaptation for nonshivering thermogenesis and of the role of the brown adipose tissue in the development and maintenance of this adaptation.

Control of lipid metabolism in cultured cells.

Abstract: Several studies are presented which indicate that composition of cell lipid is regulated by interaction between intracellular metabolism and lipid transport processes. When the fatty acid composition of cells cultured in essential fatty acid deficient conditions was studied, activation of synthesis of unusual polyun-saturated fatty acids was observed for a number of cell lines. In addition cells contained persistent residual amounts of linoleic acid, presumably owing to efficient scavenging mechanisms. The source of cell lipids was studied in both chemically defined and serum-supplemented media. In the absence of exogenous lipid, cells synthesize lipids from simple precursors, a process which is inhibited by adding serum. When serum lipid is present, cells preferentially utilize fatty acids as a source of nonsterol lipid. These are subsequently esterified intracellularly to make glycerides and phospholipids. When triglyceride is utilized as a source of cell lipid, it is first hydrolyzed before being taken up. By use of a nonhydrolyzable cholesterol ester analog, it is confirmed that both free and ester cholesterol are taken up and excreted by cells. Intracellular cholesterol content is thus regulated by rates of uptake, hydrolysis and excretion as well as by biosynthesis.

Possible mechanisms of autoxidative rancidity

Abstract: Rancidity appears as a very complex phenomenon if we consider the numerous reaction products that have been identified. Based on gas liquid chromatographic analysis of the aldehydes, alcohols, alkyl formates and hydrocarbons produced by the autoxidation of oleic acid and nonanal, an explanation of some possible reaction pathways is presented. Rancidity is described as a result of a succession of reactions, some of which are free radical in form, initiated by oleic monohydroperoxides. These yield aldehydes that are autoxidizable and also yield, by specific recurrent reactions, the wide variety of products encountered that are offensive in taste and odor.

Accumulation of cardiac fatty acids in rats fed synthesized oils containing C22 fatty acids.

Abstract: Synthesized oils containing a high proportion of oleic, eicosenoic or docosenoic acid were fed to weanling rats as 20% w/w of the diet. After 1 week, a high intake of eicosenoate produced cardiac fat droplets detected histologically, whereas erucate (22∶1 Δ 13) or cetoleate (22∶1 Δ 11) caused an appreciably greater accumulation of cardiac lipid characterized by the dietary fatty acids.

Effects of pH, concentration and aging on the malonaldehyde reaction with proteins

Abstract: Malonaldehyde, a major product of unsaturated lipid oxidation, reacts with enzymes to cause inactivation, fluorescence production and crosslinking. The pH dependence for each of these reactions shows a different optimum. Investigation of the stability of malonaldehyde shows that it undergoes decomposition which is dependent on time, reagent concentration and pH. The products resulting from this decomposition are also capable of causing enzyme inactivation and fluorescence production.

Fatty acid interrelationships in plasma, liver, muscle and adipose tissues of cattle fed safflower oil protected from ruminal hydrogenation.

Abstract: Steers were given diets containing formaldehyde-treated casein-safflower oil supplements, in which the constituent 18∶2 was protected from ruminal hydrogenation. A similar group was given unsupplemented diets. The fatty acid compositions of plasma, liver, muscle and adipose tissue lipids were determined in both groups of cattle after 0, 2, 4 and 8 weeks of experimentation. The proportion of 18∶2 in the triglycerides was markedly increased on feeding the supplement and the rate of incorporation into the plasma triglycerides was higher than that in the triglycerides of muscle and adipose tissue. Associated with this increase there were compensatory decreases in the proportions of 16∶0 and 18∶1 but no consistent change in the proportion of 18∶0. The proportion of 18∶2 in the plasma phospholipids and cholesteryl esters was initially much higher than in the triglycerides and this was further increased by feeding the safflower oil supplement. A linear relationship existed between the proportion of 18∶2 in the phospholipids and cholesteryl esters of plasma. The supplement also caused substantial increases in the proportion of 18∶2, both in phospholipids from liver and muscle and in cholesteryl esters from liver, and there were compensatory decreases in the proportions of other unsaturated fatty acids, e.g., 18∶1, 18∶3, 22∶6. These studies demonstrate that when ruminal hydrogenation was circumvented by feeding formaldehyde-treated casein-safflower oil particles, the linoleic acid was absorbed and the pattern of incorporation into plasma and tissue lipids was similar to that in nonruminants.

The distribution of cyclopropane and cyclopropene fatty acids in higher plants (Malvaceae)

Abstract: The occurrence and distribution of cyclopropane and cyclopropene fatty acids has been investigated in seeds, leaves and other tissues of several species of Malvaceae. Sterculic and malvalic acids and their dihydro-analogs were present in all the plant tissues examined, the highest proportions generally being in immature seeds. The cyclic acids were mainly concentrated in the neutral lipids with lesser proportions in phospholipid or glycolipid classes. The occurrence of these acids in all tissues of some species offered the attractive possibility of establishing callus tissue cultures capable of synthesizing cyclopropane and cyclopropene fatty acids and thereby providing a more convenient and reproducible system for biosynthetic studies. Substantial proportions of these cyclic acids were found in callus tissue cultures propagated from twoMalva species.

Long term human studies on the lipid effects of oral calcium.

Abstract: Ingestion of 2 g of supplemental dietary calcium carbonate daily over a period of one year by eight hyperlipemic men and two hyperlipemic women caused a significant 25% decrease in serum cholesterol, after these subjects had shown stable levels for the previous year, and when compared to a group without therapy. Body weights for both groups remained stable throughout the period of observation. The experimental group also showed a reversal in the cholesterol-phospholipid ratio from a preexperimental ratio of 1.04 to a ratio of 0.92. In addition there was a 113 mg per 100 ml decrease in serum triglycerides and a 48 mg per 100 ml decrease in serum phospholipids, but these were not statistically significant due to the large between individual variations and the limited sample size. Calcium carbonate should be considered as a potential agent for usage in long term studies designed to produce hypolipemia, since it appears to be effective and without significant side effects.

Biosynthesis of brain sphingolipids and myelin accumulation in the mouse.

Abstract: Microsomal fractions were prepared from the brains of mice sacrificed at 13 are points between 5 and 48 days of age. Several enzymatic activities implicated in sphingolipid biosynthesis were assayed. The developmental pattern for the terminal step in galactosylceramide synthesis, transfer of galactose from UDP-galactose to ceramide, peaked sharply at 17–19 days of age. Thus maximal activity for biosynthesis of this relatively myelin specific lipid appears slightly before the time period of maximal rate of accumulation of myelin (21–23 days). These latter data were obtained by isolating myelin from mice at 10 age points from 9 to 45 days of age. A control enzymatic activity, transfer of glucose from UDP-glucose to ceramide to form glucosylceramide, was high at all age points with a broad peak between 20 and 35 days of age. Condensation of palmitoyl-CoA and serine to form ketodihydrosphingosine, a common precursor to both glucosyl- and galactosylceramide also followed a developmental pattern of high activity at all age points, but peaked slightly at ca. 10–12 days of age.

Radical addition of linoleic hydroperoxides to α-tocopherol or the analogous hydroxychroman

Abstract: Either linoleic acid hydroperoxide (LOOH) or methyl linoleate hydroperoxide react anaerobically with either α-tocopherol (TOH) or its model compound-2,2,5,7,8-pentamethyl-6-hydroxychroman (COH)-to form principally an addition compound of the two reactants. The reaction can be catalyzed either by 1.28 X 10−5 M Fe(III) or by proflavin (0.01%) sensitized by visible light. The presence of air in the reaction terminates the addition, and quinones become the major products from TOH or its model compound. The addition compound synthesized from COH and LOOH (a 4.9∶1 ratio of 13-hydroperoxy-cis-9,trans-12-octadecadienoic acid and 9-hydroperoxy-trans-10,cis-12-octadecadienoic acid) was used to solve structural details of the bridging function. Three isomers of the addition compound (methyl esterified) were isolated and identified as methyl 11-(2,2,5,7,8-pentamethyl-6-oxychroman)-cis-12,13-epoxy-trans-9-octadecenoate; methyl 11-(2,2,5,7,8-pentamethyl-6-oxychroman)-trans-12,13-epoxy-trans-9-octadecenoate; and methyl 11-(2,2,5,7,8-pentamethyl-6-oxychroman)-cis-9,10-epoxy-trans-12-octadecenoate in order of decreasing abundance. The mechanism appears to be free radical addition brought about by the catalytic formation of alkoxy radicals from the hydroperoxide and chromanoxy radicals from TOH or its model.

Hydroperoxides from oxidation of linoleic and linolenic acids by soybean lipoxygenase: Proof of thetrans-11 double bond

Abstract: Hydroperoxides produced by oxidation of linoleic and linolenic acids with soybean lipoxygenase were analyzed by nuclear magnetic resonance. The isomerized double bond α,β to the hydro-peroxide group at carbon-13 was determined to betrans. The complete structures of the major products proved to be 13-hydroperoxy-cis-9,trans-11-octa-decadienoic acid from linoleic acid and 13-hydroperoxy-cis-9,trans-11,cis-15-octadecatrienoic acid from linolenic acid. The configuration of the double bonds indicates that oxidation took place through a free radical mechanism as proposed previously by others.

Surface tension studies of phosphatidyl glycerol isolated from the lungs of Beagle dogs

Abstract: Phosphatidyl glycerol, isolated from Beagle dog pulmonary surfactant, was found to have surface tension properties similar to phosphatidyl choline (isolated from the same source and chemically synthesized). The results show that another phospholipid in addition to dipalmitoyl-glyceryl-phosphoryl-choline contributes to the characteristic surface tension behavior of pulmonary surfactant.

Cuticular lipids of insects: V. Cuticular wax esters of secondary alcohols from the grasshoppersMelanoplus packardii andMelanoplus sanguinipes

Abstract: Wax esters of secondary alcohols constitute 18–20% of the cuticular lipid extract ofMelanoplus packardii and 26–31% of the cuticular lipids ofMelanoplus sanguinipes. The total number of carbons in the wax esters range from 37–54 with 41 predominating in both species. The fatty acids ofM. packardii wax esters are 16∶0, 18∶0, 14∶0, 20∶0 and 12∶0 in decreasing quantity. The fatty acids ofM. sanguinipes wax esters are 18∶0, 20∶0, 16∶0 22∶0, 14∶0, 19∶0 and 17∶0 in decreasing quantity. The secondary alcohols from the wax esters ofM. packardii are C25, C23 and C27 in decreasing quantity, and the secondary alcohols of theM. sanguinipes are C23, C25, C21, C27, C24, C22 and C26 in decreasing quantity. Each secondary alcohol consists of two to four isomers with the hydroxyl group located near the center of the chain.

Azasteroids: Potent inhibitors of insect molting and metamorphosis

Abstract: Based on previous structure-activity studies, four new azasteroids were synthesized and tested in several species of insects. These compounds, which are the most potent azasteroid inhibitors of insect growth and development tested to date, affect the hormone-regulated processes of molting and metamorphosis.

Ring position in cyclopropene fatty acids and stearic acid desaturation in hen liver.

Abstract: Four cyclopropene fatty acids, having the double bond of the cyclopropene ring at the 8,9, 9,10, 10,11 and 11,12 positions, respectively, were tested as inhibitors of stearic acid desaturation by the desaturase enzyme system of hen liver. The first three were powerful inhibitors, but the last was not. The cyclopropene acids with the 9,10 and 10,11 double bonds were equally strong inhibitors, while the acid with the 8,9 double bond was less effective. To account for the specificity of those cyclopropene fatty acids in which the C9 or C10 carbon atom is included in the cyclopropene ring, it is suggested that the conformation and structure of the CoA derivatives of these acids is such that they can irreversibly occupy the site on the enzyme responsible for 9,10-desaturation.

Studies on drug-induced lipodosis. V. Changes in the lipid composition of rat liver and spleen following the administration of 4,4'-diethylaminoethoxyhexestrol.

Abstract: Administration of 4,4′-diethylamino-ethoxyhexestrol increased total phospholipids and free cholesterol in rat liver. An elevation of a peculiar glycerophospholipid, lysobisphosphatidic acid, was marked both in liver and spleen. An increase in phosphatidylinositol was also noticed in spleen. However these changes in rats were not so marked as in human cases. There was an accumulation of a substance in rat tissue which was identified as a derivative of the drug, while the intact drug accumulated in large amount in human cases. Differences in the effect of 4,4′-diethylaminoethoxyhexestrol on lipid metabolism between human and rat seem to be related to the difference in drug digesting ability between these two animal species.

Regulation of lipid metabolism in in vitro cultured minimal deviation hepatoma 7288C.

Abstract: Hepatoma tissue culture (HTC) cells (derived from minimal deviation hepatoma 7288C) were cultivated in a complete medium containing either glucose, fructose or glycerol as the primary carbon source. Growth was rapid on glucose and very low on fructose containing media. Glycerol did not support any growth. Glucose-14C (U) and fructose-14C (U) are incorporated into the total lipid fraction of HTC cells. However the level of conversion of glucose into lipid is much greater than fructose. Tritiated water is rapidly incorporated into the saponifiable and nonsaponifiable lipid fractions of growing HTC cells. The level of incorporation is greater than that observed with glucose-14C (U) and the difference is constant over the experimental period studied. Lipoprotein poor serum (LPPS) isolated from a calf-fetal calf serum mixture (1∶1) supported growth at a similar rate as the unfractionated serum combination (DS). However the total lipid and total cholesterol content of the fractionated serum was one sixth and one fiftieth the level found in the whole serum mixture, respectively. The level of incorporation of glucose-14C (U), acetate-14C (U) and tritiated water into the nonsaponifiable fraction of HTC cells grown on LPPS was 3 to 8-fold greater than that for DS. However mevalonate-2-14C incorporation was stimulated only 1.3 to 1.7-fold. In general there was a much smaller response in the level of incorporation of radioactive metabolites into the saponifiable lipids. From these studies and additional data, it was tentatively concluded that HTC cells can respond to nutritional pertubations caused by changes in the exogenous lipid content. It was not determined if the apparent responsiveness in the lipids of the nonsaponifiable fraction is due to “feedback control” or some other regulatory mechanism.

Effects of surface concentration, metals and acid synergists on autoxidation of linoleic acid monolayers on silica

Abstract: To approximate in a model system the autoxidation of monomolecular layers of lipids on the cell surfaces of freeze-dried foods, the autoxidation of presumed monolayers of linoleic acid adsorbed from solution onto silica gel has been studied as a function of time and α-tocopherol and acid synergist content The method of Honn, Bezman and Daubert was used, modified by the substitution of linoleic acid for soybean oil and the use of gas chromatography to follow oxygen disappearance at 80 C It was found that adsorption of linoleic acid onto silica gel from petroleum ether solution conforms to a Langmuir isotherm, consistent with the formation of a monolayer Confirming the finding of Honn et al with soybean oil, it was found that the most rapid uptake of oxygen occurred at a linoleic acid-silica ratio close to that for the monolayer Without included antioxidant, oxidation commences at a nearly linear rate without observable induction period Time for consumption of one-half mole of oxygen per mole of linoleic acid is ca 60 min on acid-washed silica If very small amounts of α-tocopherol are included in the layer, virtually no oxygen uptake measurable in this system occurs during an induction period, the length of which is approximately proportional to tocopherol content The inflection point at the commencement of rapid oxidation is very sharp; the ensuing oxidation rate approximates that of the unprotected acid The induction period of linoleic acid with the same tocopherol content is as much as 100% longer when exposed in monolayer than in a bulk form However the rate after commencement of rapid oxidation is 8–10 times greater in the monolayer Acid washing of the silica reduced its iron content by 75% Acid washing also reduced by 60% the rate of autoxidation without α-tocopherol and increased the length of the induction period four-fold when α-tocopherol was present The effect of pretreatment of the silica by adsorption of the acid synergists, ascorbic, phosphoric, citric and ethylenediamine tetraacetic acid was qualitatively similar to the effect of acid washing The synergists extended the induction period in increasing order as listed, EDTA producing a 100-fold extension For ascorbic acid the rate reduction and increase of induction period were not found on unwashed silica and were dependent on the extent of washing These findings are consistent with synergist sequestration of metals in a complex that is ineffective in new chain generation by perioxide decomposition

Occurrence of glyceryl tridocosahexaenoate in the eye of the sand troutCynoscion arenarius

Abstract: The pigment epithelium of the eye of the sand trout (Cynoscion arenarius) contains a reflecting layer or tapetum lucidum, consisting of lipid spherules approximately 400 nm in diameter. The lipids consist amost exclusively of triglycerides and the fatty acids contain up to 95% docosahexaenoic acid. Thus the lipid of this reflecting layer appears to be nearly pure glyceryl tridocosahexaenoate. The adjacent tissues contain much less docosahexaenoic acid (retina 65%; choroid 9%) and little, if any, tridocosahexaenoin. The possible importance of this nearly pure, highly unsaturated, mono acid triglyceride is briefly discussed.

Progestagens, anabolic‐androgenic compounds, estrogens: Effects on triglycerides and postheraprin lipolytic enzymes

Abstract: Oral contraceptives, estrogens, progestagens and anabolic-androgenic compounds have extensive effects on plasma triglycerides and on triglyceride clearing enzymes. This review will center on recent advances in the understanding of the mode of action of these compounds, both in normals and in patients with hyperlipoproteinemia.