Showing papers in "Lipids in 1973"

Fluorescent products of phospholipids during lipid peroxidation.

Abstract: During peroxidation, phosphatidyl ethanolamine and phosphatidyl serine formed fluorescent chromophores with maximum emission at 435 nm and maximum excitation at 365 nm. The development of fluorescence was related to formation of thiobarbituric acid reactive substance during lipid peroxidation. This relationship was studied by reacting dipalmityl phosphatidyl ethanolamine with the oxidation products of the methyl esters of arachidonic, linolenic and linoleic fatty acids. Reaction parameters affecting the development of lipid-extractable fluorescent chromophores are: the production of peroxidation products, especially malonaldehyde, from autoxidation of polyunsaturated fatty acids; the length of time these products react; and the availability of reactive amino groups on the phospholipids.

Damage to microsomal membrane by lipid peroxidation.

Abstract: Alterations of microsomal membrane integrity were examined during lipid peroxidation. Loss of membrane-bound NADPH cytochromec reductase activity and protein release into the aqueous phase were related to disruption of the lipophilic region of the membrane. Formation of fluorescent products in the lipid phase of the membrane occurred only in the presence of peroxidation products. Changes in the membrane lipid phase during peroxidation included a decrease in the reactive amino groups of the phospholipids and a decrease in detectable phosphatidyl ethanolamine. In an ultrafiltration continuous flow chamber, peroxidized microsomal membranes were hydrolyzed to a lesser degree by solubilized lysosomal cathepsins and to a greater degree by lysosomal nucleases than were nonperoxidized membranes.

Fluorescent products from reaction of peroxidizing polyunsaturated fatty acids with phosphatidyl ethanolamine and phenylalanine.

Abstract: Fluorescent chromophores produced by reaction of peroxidizing arachidonic acid or methyl docosahexaenoate with synthetic dipalmityl phosphatidyl ethanolamine were lipid soluble, and those from reaction with phenylalanine were water soluble. In all reaction systems that contained polyunsaturated fatty acid and only one amine compound, the development of fluorescence was linearly related to oxygen absorption for 12–24 hr (p<0.001) and to the amount of thiobarbituric acid reacting materials until the rate of oxygen absorption decreased. The fluorochromes typically had maximum excitation at 360 nm and maximum emission at 430–440 nm, indicating that they were conjugated Schiff bases with the general structure R−N=C−C=C−N−R, where R represents the amino acid phenylalanine or the phospholipid phosphatidyl ethanolamine. The fluorochromes were similar to those extracted from isolated age pigments and tissues of animals that are aged, vitamin E-deficient, or stressed with highly unsaturated lipid diets.

A new reaction of unsaturated fatty acid hydroperoxides: Formation of 11-hydroxy-12,13-epoxy-9-octadecenoic acid from 13-hydroperoxy-9,11-octadecadienoic acid

Abstract: One of the main compounds formed from 13L-hydroperoxy-9cis,11trans-octadecadienoic acid anaerobically at 100 C in aqueous ethanol was found to bethreo-11-hydroxy-12,13-epoxy-9-octadecenoic acid. The major part (ca. 90%) of this compound was formed from the fatty acid hydroperoxide in a reaction involvingcis-addition to the Δ11 double bond of the proximally linked hydroperoxide oxygen and hydroxyl ion or hydroxyl radical from the solvent. A small part (ca. 10%) was formed bycis-addition of the two hydroperoxide oxygens to the Δ11 double bond. 11-Hydroxy-12,13-epoxy-9-octadecenoic acid and its isomer, tentatively identified as 11-hydroxy-9,10-epoxy-12-octadecenoic acid, also were isolated from a sample of autoxidized linoleic acid.

Role of luminal lecithin in intestinal fat absorption.

Abstract: The effects of biliary lecithin on fat absorption were studied in 1 day bile fistula rats fed micellar solutions of bile salt, monoglyceride and radioactive free fatty acids By electron microscopy and measurement of uptake of radioactivity into liver and adipose tissue, it was shown that in the absence of bile lecithin there was significant impairment of fat release from mucosa Fat clearance was effected by the feeding of phosphatidyl choline or choline, but not phosphatidyl ethanolamine, inositol or cholesterol In the absence of luminal choline there was a decrease in incorporation of radioactive leucine into mucosal protein It is concluded that biliary and dietary lecithin or choline play an important role in triglyceride transport out of intestinal mucosa, by providing surfactant lecithin for the chylomicron envelope and by supporting mucosal protein biosynthesis

Fluorescent product formation and changes in structure of DNA reacted with peroxidizing arachidonic acid.

Abstract: Calf thymus DNA was reacted with peroxidizing arachidonic acid at 37 C for 76 hr. Fluorescent DNA products increased with reaction time. These products had characteristic fluorescence spectra with maximum excitation at 315 nm and maximum fluorescence at 420 nm. Structural changes occurred in the DNA reacted with peroxidizing arachidonic acid, as observed by decreased melting point, decreased hyperchromicity, partial resistance to hydrolysis by deoxyribonuclease and by decreased template activity for rat liver RNA polymerase.

Effect of double bond position in octadecenoates upon hydrolysis by pancreatic lipase.

Abstract: Fifteen triacylglycerols containing 12∶0, 14∶0, 16∶0, 18∶2 and one positional isomer ofcis-18∶1 were hydrolyzed by pancreatic lipase (EC 3.1.1.3, glycerol ester hydrolase). The fatty acids in the products of lipolysis were identified and measured by gas liquid chromatography. The substrates containing the Δ2 through Δ7 isomers of 18∶1 were resistant to pancreatic lipolysis. These isomers accumulated in the di- and residual triacylglycerols and were diminished in the free fatty acids. The discrimination was greates against the Δ5 isomer.

Studies on in vitro peroxidation of liver lipids in ethanol treated rats

Abstract: It has been confirmed that lipid peroxidation of liver homogenates is increased following acute ethanol intoxication. Studies with recombined fractions of the liver suggest that the cause for the ethanol-induced increase in malonic dialdehyde production is located in the soluble fraction. Reduced glutathione content of the liver supernatant is decreased following ethanol intoxication. The decrement, however, occurs after the increase in malonic dialdehyde production takes place. Glutathione reductase and glutathione peroxidase activities of the liver are unaffected by ethanol administration. It is suggested that the decrease in reduced glutathione content may reflect a condition of increased peroxidation in vivo.

Analysis of lipoxygenase nonvolatile reaction products of linoleic acid in aqueous cereal suspensions by urea extraction and gas chromatography.

Abstract: Cereals contain lipoxygenase and small quantities of linoleic and linolenic acids. For studying the oxidation of these acids by lipoxygenase in aqueous cereal suspensions and especially in doughs of wheat flour, an extraction method was developed, providing a means of quantitative extraction of the acids and their oxidation products. A complete extraction can be obtained by using urea as a disclosing agent and a chloroform-isopropanol mixture as the extraction solvent. For the detection of the acids and their oxidation products, some of which are formed in relatively small amounts, a gas chromatographic method was developed. After extraction, the products are first methylated and silylated; then, along with an internal standard, determined with the aid of gas liquid chromatography. This method permits the determination of mono-, di-, and trihydroxy acids, as well as of the ketodihydroxy and α and γ ketols.

Circadian rhythm of fatty acid desaturation in mouse liver.

Abstract: A study was made of the diurnal changes in liver microsomal desaturation of labeled stearic, linoleic and α-linolenic acids to oleic, γ-linolenic and octadeca-6,9,12,15-tetraenoic acids, respectively. C3H-S mice were used and were exposed to light-dark cycles. A circadian rhythm was observed for stearic acid desaturation, and a different one for linoleic acid. Linoleic and α-linolenic desaturation had similar responses in the day cycle. This would indicate that different mechanisms control the oxidative desaturations of the fatty acids in the 9 and 6 carbons. The fatty acid composition of the whole liver and liver microsomes also showed variations. Remarkable oscillations were observed for stearic and oleic acids. Neither the total protein synthesis nor the free fatty acid concentration in the microsomes followed a rhythm parallel to the desaturation of the studied fatty acids. The injection of cycloheximide 4 hr before measuring the desaturation modified the circadian variation of both the 9 and 6 desaturations. The modification induced by cycloheximide was considered to indicate that both variations are related to the synthesis of specific proteins but not to that of a degradative or inhibitory protein.

Fluorescent products of lipid peroxidation: I. Structural requirement for fluorescence in conjugated schiff bases

Abstract: The structural requirement for fluorescence in Schiff bases was defined. Aldehydes and amines were reacted and the structures of the Schiff bases N-hydroxyethyl-1-imino-2′,4′-hexadiene (I), N-1-benzal-2-hydroxyaminoethane (II), and N-1-benzal-2,2′-hydroxyaminoethane (III) were established by elemental analysis, IR spectral analysis and mass spectral analysis. The structures of N-alanyl-2-hydroxy-naphthylidine (IV) and N,N′-dileucinyl-1-amino-3-iminopropene (V) had been established previously. III, IV and V were fluorescent compounds and I and II were not. The results of these analyses suggest that an electron donating group in conjugation with an imine is the structure required for fluorescence.

Effects of chronic alcohol ingestion on the fatty acid composition of the heart.

Abstract: The effects of alcohol on the total fatty acid composition of the heart have been measured, and two highly significant differences were noted between the alcohol-treated animals and the two control groups. Linoleic acid was elevated, and arachidonic acid was decreased. The increase in linoleate appeared to be a generalized increase within the various lipids analyzed, whereas the decrease in arachidonate was accounted for largely in the phosphatidyl cholines. The ratios of 20∶4ω6/18∶2 were calculated and compared to data from other researchers. The decrease in this ratio in the hearts from the alcohol-treated animals was similar to the data from the liver of animals treated with various agents which produce a fatty liver. Various mechanisms that could cause such changes in these two essential fatty acids are discussed, and it was concluded that a combination of effects could cause these changes in linoleate and arachidonate. These effects include: (a) increased mobilization of linoleate from adipose tissue; (b) decreased β-oxidation of linoleate; and (c) inhibition of the elongation-desaturation system which converts linoleate to arachidonate.

Lipoxygenase inChlorella pyrenoidosa

Abstract: The presence of lipoxygenase enzyme is observed when cells ofChlorella pyrenoidosa are homogenized under anaerobic conditions. This is the first report of this enzyme in a lower form of plant life. The major product ofChlorella lipoxygenase with linoleic acid as substrate is 13-hydroperoxyoctadecadienoic acid.

Enzymatic oxidation of linolenic acid in aqueous wheat flour suspensions

Abstract: Linolenic acid oxidation by the enzyme lipoxygenase in an aqueous wheat flour suspension does not lead to accumulation of linolenic acid hydroperoxides but immediately to secondary oxidation products. The 3 most important products among these were identified as 9-hydroxy-trans-10,cis-12,cis-15-octadecatrienoic acid, 9-hydroxy-10-oxo,cis-12,cis-15-octadecadienoic acid, and 9,12,13-trihydroxy-trans-10,cis-15-octadecadienoic acid.

Leaf wax of oats.

Abstract: Leaf wax of oats (Kelsey variety) consists of hydrocarbons (5%), esters (10%), free alcohols (45%), free acids (2.5%), β-diketone (5.5%), hydroxy-β-diketones (2.5%), and unidentified (29%). Wax on leaf blades contains more free alcohols than wax on leaf sheaths, and wax on the flag leaf sheath contains more β-diketone than wax on the rest of the plant. Principal hydrocarbons are C29, C31, and C33. The esters, mainly C44-C48 and C52, are probably C18-C22 and C26 esters of hexacosanol. Free alcohols are almost entirely hexacosanol. The β-diketone is hentriacontane-14, 16-dione. Hydroxy β-diketones are a mixture of 5-, 6- and 7-hydroxyhentriacontane-14, 16-diones in the proportions 58∶35∶7. The wax also contains a small amount (0.5%) of 1,16-hexacosanediol.

Nature of fecal sterols and intestinal bacterial flora.

Abstract: Sterol excretion in the spontaneously atherosclerosis-susceptible White Carneau (WC) pigeon, the Silver King (SK) pigeon and the Show Racer (SR) pigeon was studied by thin layer chromatography (TLC), argentation TLC and gas liquid chromatography. Unlike man and the chicken, these pigeons excreted no coprostanol or coprostanone derivatives of sterols. Moreover incubation of14C-labeled cholesterol with pigeon feces indicated that, also unlike man and the chicken, these pigeons are unable to convert it to coprostanol. Bacteriologic examination revealed the absence of gram-negative anaerobic flora and of members of the genusBifidobacterium in both the WC and SR pigeons. On the other hand, one of the two SK pigeons examined showed evidence of the presence of bothBacteroids fragilis andB. bifidum in the upper intestinal tract. Although no qualitative experiments were performed, no unusual characteristics of the aerobic flora were noted in these pigeons. In addition, analysis of human stool specimens indicated a “normal” bowel flora. The flora of the intestinal tract of the chicken is similar to that of the human. Because of this similarity, it appears that differences in environment (living conditions, diets) between the human and the chicken are of little consequence. The results obtained in this study suggest the possibility that the anaerobic gram-negative flora and sponsible, at least in part, for the chemical conversion of cholesterol to coprostanol.

Effects of ethanol on membrane lipids III. Quantitative changes in lipid and fatty acid composition of nonpolar and polar lipids of mouse total liver, mitochondria and microsomes following ethanol feeding

Abstract: The effects of ethanol on the total, nonpolar, and polar lipids of whole liver, mitochondria, and microsomes have been evaluated. Differences in the fatty acid composition of various lipid subclasses have been compared in control and ethanol treated mice. On the whole polyunsaturated fatty acids, especially arachidonic (20∶4) and docosahexaenoic (22∶6), were found to decrease. The significance of an enzymatic mechanism vs. a peroxidative mechanism to explain the results is discussed. Decreases also were observed in the ratios of arachidonate/linoleate following ethanol feeding. These changes are thought to be associated with decreases in the activity of the chain elongation-desaturation system.

Bis-(monoacylglyceryl)-phosphate of rat and human liver: fatty acid composition and NMR spectroscopy.

Abstract: Bis-(monoacylglyceryl)-phosphate was isolated from liver lysosomes that had been prepared from rats pretreated with Triton WR-1339. Analysis of the fatty acids in this lipid by gas chromatography and mass spectrometry revealed that they were composed of 69% docosahexenoic acid. NMR spectroscopy of bis-(monoacylglyceryl)-phosphate isolated from liver of a patient who had a lipid storage disease revealed that the peak corresponding to the chemical shift of protons of esterified secondary carbons of glycerol was absent. This suggests that fatty acids are esterified to the primary position of both glycerols.

Sulfated bile acid in urine of patients with hepatobiliary diseases.

Abstract: The presence of sulfated bile acid in urine of patients with hepatobiliary diseases was recognized by using an Amberlite XAD-2 column for extraction of bile acid and a Sephadex LH-20 column for separation of sulfated (sulfate of either taurine or glycine conjugate) and nonsulfated bile acid (taurine and glycine conjugate). Sulfated and nonsulfated bile acid, obtained after a Sephadex LH-20 column of urinary extract of the patient with acute hepatitis, was identified by thin layer chromatography. Sulfated bile acid showed a spot with different Rf value from that of taurine-conjugated, glycine-conjugated and free bile acid, and solvolysis of sulfated bile acid resulted in a compound with the same Rf value as glycodihydroxycholanoic acid. A large amount of bile acid sulfate was found in urine of patients with hepatobiliary diseases. The sulfated bile acid in these urine samples occupied from 57.1 to 93.3% of total bile acid, and consisted of both di-and trihydroxycholanoic acid (major part, chenodeoxycholic acid). As no solvolysis was carried out in previous works, bile acid sulfate in urine, as described in this paper, was not determined at all.

Lipids of cultured hepatoma cells: II. Effect of media lipids on cellular phospholipids

Abstract: Minimal deviation hepatoma cells were cultured in a modified Swim's 77 medium supplemented with decreasing amounts of serum, lipid-free serum, and lipid-free serum containing added palmitic or linoleic acids. Cellular phospholipids were extracted and the class distribution determined quantitatively. The fatty acid composition of each phospholipid class was determined, and the percentages from cells grown on each of the various media were compared. Cellular phospholipid class and fatty acid compositions differed from media compositions, indicating that intact serum phospholipids are not incorporated into cellular structures. Phosphatidylcholine percentages decreased as the media serum and lipid levels decreased, while phosphatidylinositol and phosphatidylethanolamine percentages increased. Sphingomyelin of cells grown in medium containing added linoleic acids contained a high level of a 24∶2 acid. All classes, except sphingomyelin, contained elevated levels of 18∶1 acid and decreased levels of polyunsaturated fatty acids, relative to normal rat liver. Cells cultured on lipid-free medium did not contain increased concentrations of 20∶3 acid, suggesting that this hepatoma cell cannot desaturate monoenoic acids. Phosphoglycerides of cells, grown on lipid-free medium, had the highest monoene fatty acid concentration, whereas those cells grown on media containing added linoleic acid had the lowest concentrations, suggesting that linoleate may inhibit or regulate monoenoic acid biosynthesis in this cell. These mass data also demonstrate that monoenoic fatty acid biosynthesis in this cultured hepatoma cell responds to dietary changes.

Distribution oftrans-6-hexadecenoic acid, 7-methyl-7-hexadecenoic acid and common fatty acids in lipids of the ocean sunfishMola mola

Abstract: Lipids extracted from various tissues of four individual sunfish have been shown to contain thetrans-6-hexadecenoic acid previously reported for marine turtles, a metridium and a jelly fish, and also the 7-methyl-7-hexadecenoic acid recently isolated from one sunfish liver oil sample. The other fatty acids present were qualitatively typical of marine lipids in general. Unusual quantitative details included high percentages of 18∶0 and 20∶4ω6, which are also found in the Atlantic leatherback turtle and presumably linked to a similar diet of jellyfish and to other common factors. In a sample of lipids from intestinal contentstrans-6-hexadecenoic acid was found to be the predominant C16 monoene, and was accompanied by comparatively large amounts of the 7-methyl-7-hexadecenoic acid. This observation and other fatty acid details are compatible with an exogenous origin for these acids and jellyfish, etc., as a predominant dietary material for the ocean sunfish.

Changes in lipid composition of germinating barley embryo.

Abstract: Barley seeds,Hordeum vulgare, var. Kenia, were dissected before and after 5 days of germination, to distinguish between the scutellum, the coleoptile half of the embryo and the coleorhiza half of the embryo. Total lipids were extracted from each fraction and analyzed by thin layer chromatography and gas liquid chromatography. In tissues from the coleoptile and coleorhiza halves of the embryo there was a concurrent disappearance of triglycerides with a marked increase of esterified sterols and esterified sterol glucosides. In the scutellum there was also a change in triglycerides, but the variations in contents of esterified sterols and esterified sterol glucosides were much smaller. Mono- and digalactolipids were virtually absent from embryonic tissue. The amounts of linoleic and linolenic acids in esterified sterol glucosides were increased after 5 days of germination in all the embryonic tissues, especially in the coleoptile half. In sterol esters, linoleic acid comprised nearly half of the total fatty acids, and the desaturation after 5 days of germination was much less pronounced.

Characterization of toxic compound in thermally oxidized oil

Abstract: In preliminary experiments, soybean oil was heated at 275 C for 12 hr in the presence of N2 or air. Feeding studies with rats showed that the oil heated in the presence of air, oxidatively polymerized oil, retarded weight gain more than that heated with N2, thermally polymerized oil. Oxidatively polymerized oil was fractionated with silicic acid column chromatography, and the fraction eluted with ether (fraction III) proved to be most toxic to mice. For chemical studies combined with bioassays, additional oxidatively polymerized oil was prepared by aeration at 185 C for 90 hr, and the product was fractionated by silicic acid column chromatography. The material originally eluted with ether (fraction III) was eluted in stages, and fraction IIIc proved to be most toxic in a mouse bioassay. IR, UV and NMR analyses did not indicate the presence of C−O−O−C or C−O−C linkages or aldehyde groups or aromatic compounds. Fraction IIIc was converted to its methyl esters and molecularly distilled to yield two fractions: one containing unpolymerized fatty acid esters and one giving evidence of more functional groups per molecule and of dimeric material. This “dimeric” fraction was more toxic to mice. IR analysis of this fraction revealed carbonyl groups, and NMR showed several functional groups on alkyl chains. Treatment with sodium borohydride and with hydroiodic acid revealed no C−O−O−C and no C−O−C linkages. Mass spectrography showed peaks at mass 586 and 293; in the reduced fraction a peak also occurred at mass 143, suggestive of cleavage of some of the chains. It is tentatively concluded that a highly toxic material formed in oil heated in air is a dimer of triglyceride molecules.

Symposium: biological significance of autoxidized and polymerized oils.

Abstract: Groups of 40 male Charles River rats were fed diets containing cottonseed oil, olive oil, corn oil, soybean oil, coconut oil, chicken fat, beef fat, butter oil, lard and saturated medium chain triglycerides. The fats were fed fresh and after 40 hr aeration at 60 C, which hardly changed peroxide values. In addition, fresh and aerated soybean oil and lard were fed to W/Fu rats. Body weights and life span were significantly influenced by the kind of fat fed, but not by aeration. Many hearts exhibited unspecific focal myocarditis and focal fibrosis. The latter was graded in a blind test, which revealed highly significant differences in the incidence of severe lesions; those fed corn oil had the most, followed by cottonseed oil, soybean oil, olive oil, beef fat, saturated medium chain triglycerides, butter, chicken fat and lard, in that order. Feeding of aerated fat resulted in an increased incidence with six of the eight fats. The W/Fu rats had lower incidences, but those fed soybean oil had more than those fed lard, and aeration led to a higher incidence. Some heart sections stained with Light Green SF Yellowish revealed areas of muscle fibrils that did not accept the stain, probably as a consequence of cellular damage. Higher incidences of this lesion were associated with the same fats as was severe fibrosis, and feeding of aerated fats led to higher incidences. Many livers revealed marked proliferation of bile ducts. The groups fed cottonseed, soybean, olive and corn oils had higher incidences of severe lesions, and feeding of the oxidized oils led to still higher incidences. None of the results appeared to be associated with the fatty acid composition of the fats, which suggested that these long term effects may have been due to minor constituents in the individual fats.

Determination of molecular species of ovolecithin using gas chromatography-mass spectrometry.

Abstract: An analysis of monoacetyldiglyceride was performed by gas chromatographymass spectrometry for the purpose of determining the molecular species of ovolecithin. Separation of monoacetyldiglycerides was made according to the degree of unsaturation and to the sum of the carbon numbers of fatty acyl residues. Fragments of monoacetyldiglyceride were analyzed and interpreted in relation to the molecular structure in a similar manner to that of triglyceride.

Lipids of cultured hepatoma cells: I. Effect of serum lipid levels on cell and media lipids

Abstract: Minimal deviation hepatoma cells were cultured as monolayers to confluency in roller flasks containing modified Swim's medium, supplemented with decreasing amounts of serum, lipid-free serum, and lipid-free serum containing added fatty acids. Good cell growth was observed until serum levels fell below 5% of the medium. Media containing lipid-free serum or lipid-free serum plus linoleic or palmitic acids did not support good growth. Lipids were extracted from cells; media, obtained during the first and last half of the incubation period, resolved into neutral and phospholipid fractions; fatty acid composition of each fraction analyzed by gas liquid chromatography; and lipid class distributions compared by thin layer chromatography. The data showed that the media contained more neutral lipids and phospholipids after incubation than initially, indicating that minimal deviation hepatoma cells excreted lipids into the media. The class composition of the excreted lipids resembled that of the serum. A comparison of media, cells, and serum fatty acid compositions indicated that the lipids secreted into the media were of cellular origin. Although some differences were noted, in general, cells grown on the nine different media had the same ca. neutral lipid and phospholipid class and fatty acid compositions. In contrast, dramatic differences were observed in the class and fatty acid compositions of the serums from that of the cells and media. These results indicate that exogenous serum lipids had little influence on cellular class and fatty acid compositions of the minimal deviation hepatoma cells. This neoplasm did not contain detectable levels of glyceryl ether diesters, indicating that this compound is not characteristic of all tumors. Lipid class profiles and fatty acid compositions of cells grown on various media suggest that the minimal deviation hepatoma cells can synthesize most, if not all, neutral lipid and phosphoglyceride classes found in liver.

Incorporation of (1-14c)-oleic acid into neutral glycerides and phosphoglycerides of mouse brain.

Abstract: The incorporation of [1-14C]-oleic acid into the neutral glycerides and phosphoglycerides of adult mouse brain was examined between 1 and 80 min after intracerebral injection. Radioactivity of the free oleic acid in brain decreased rapidly with a half-life of ca. 5 min. The specific radioactivity of the phosphatidic acids was highest at 1 min after injection. This was followed by the diacylglycerols and triacylglycerols which attained a maximum specific radioactivity at 3 and 20 min after injection, respectively. Specific radioactivities of the neutral glycerides were higher than the phosphoglycerides. A larger proportion of the radioactivity in the diacylglycerols was transferred to the phosphoglycerides than to the triacylglycerols. Among the phosphoglycerides, radioactivity was actively incorporated into the inositol phosphoglycerides. The specific radioactivity of the inositol phosphoglycerides was higher than the diacylsn-glycero-3-phosphorylcholines, and the kinetics of incorporation of radioactivity into these lipids was also different. A water soluble material was found which showed maximum specific radioactivity at 6–10 min after injection. The properties of this water soluble material suggested that it may be an intermediate involved in the acyl group metabolism of phosphoglycerides in brain.

Plasma cholesterol levels in suckling and weaned calves, lambs, pigs, and colts.

Abstract: Plasma cholesterol levels were determined in calves, lambs, and pigs at intervals from birth until after weaning. In each case the levels were low at birth, became elevated during the suckling period, and decreased as the animals began to eat solid feed. Results with calves fed skim milk indicated that milk lipids were largely responsible for the post-partum elevation of plasma cholesterol levels. Studies with early and late weaned pigs also indicated that the elevation of plasma cholesterol in suckling animals was related to diet rather than age. Sex and breed had no apparent effect on plasma cholesterol levels in these experiments. A limited number of observations in colts indicated that plasma cholesterol levels decreased between 2 and 7 months.

Lowering of serum cholesterol by intestinal bacteria in cholesterol-fed piglets.

Abstract: Isolation of individual prostaglandins of the E group from human seminal plasma consists of three main steps: preliminary purification from other lipids; resolution of this partially purified material into various groups of prostaglandins on a column of silicic acid; and further purification and resolution of various prostaglandins of each group by reversed phase partition chromatography. The last step is time-consuming and has been replaced by a two-step thin layer chromatography: first on silica gel, which ensures purification of the PGEs, followed by argentation thin layer chromatography, which resolves them into E l , E 2 and E 3 in microgram quantities. Human seminal plasma consists of thirteen different prostaglandins (PGs), which are grouped as prostaglandins E, F, A and B, and 19-OH derivatives of A and B. There are three members in each of the E and F groups, the members of which are called primary prostaglandins because they are not interconvertible in biological systems (1). Hamberg and Samuelsson (2) have described a procedure for the isolation of individual prostaglandins from seminal plasma at pH 3.0 as a crude mixture that also consists of neutral and polar lipids. This mixture is further resolved into different groups on a silicic acid column. From each group the individual prostaglandins are resolved by reversed phase partition chromatography. For the localization of the individual members of the E group, an aliquot of each chromatographic fraction has to be examined for the presence of the PGs by means of the rise in the extinction at 278 nm in the presence of alkali. This is due to the formation of a conjugated di-enone. Instead of this time consuming process, the present report concerns a modified procedure that avoids the reversed phase chromatographic step. Thus a fast thin layer chromatographic (TLC) step on Silica Gel G followed by TLC on silver nitrate-treated silica gel may be used for the isolation, in pure state, of microgram quantities of prostaglandin E compounds. M A T E R I A L S A N D METHODS Human seminal plasma was obtained from the Copenhagen Health Insurance Organization. It was stored in ethanol 1:3 v/v at -20 C. The PGE markers used were isolated from seminal plasma by the standard method of Samuelsson (2,3). PGE 1 was obtained from Unilever, Ltd., Vlaardingen, The Netherlands. Preliminary purification of the PGs present in 300 ml seminal fluid, followed by their resolution on silicic acid column, was done according to Hamberg and Samuelsson (2) and Samuelsson (3). The ethylacetate-benzene eluate 6:4 v/v from the silicic acid column was concentrated by distilling off the solvent under reduced pressure (10 mm Hg). The residue containing 9.87 mg of PGs (Table I) was quantitatively taken up in 10 ml chloroform and 200 gl from this solution was used for further purification and quantitation on each of five plates of Silica Gel G (0.4 mm), using the solvent ethylacetate-isooctane-acetic acid-water 110:20:10:100 v/v mixture equilibrated for I hr before using the organic phase (4). The zone due to the PGE compounds (Rf 0.49) was scraped off and eluted three times with 4 ml of methanol. The extracts from the first two plates were used for the quantitation of the total content of the PGE compounds by measuring the chromophore at 278 nm in the LIPIDS, VOL. 8, NO. 7