bluuebunny/crossref_metadata_2025_split huggingface dataset:
The determination of steroids with and without natural electrophores by gas chromatography and electron‐capture detection
Authors: Poole C. F. , Zlatkis A. , Sye W. ‐F. , Singhawangcha S. , Morgan E. D. 
Published: November 2006

AbstractThe response of the electron‐capture detector to organic compounds is poorly defined, and the steroids are no exception to this observation. For those steroids which are naturally electron‐capturing, the structures of the electrophores will be defined. Other steroids can be made electron‐capturing by the formation of appropriate derivatives. Some new or infrequently used reagents for this purpose (flophemesyl ethers,t‐buflophemesyl ethers, pentafluorophenylhydrazone derivatives and halogensubstituted aromatic boronic acids) are described.
The metabolism of polyunsaturated fatty acids in rat sertoli and germinal cells
Authors: Beckman J. K. , Coniglio J. G. 
Published: November 2006

AbstractThe metabolism of [1‐14C]linoleic, [1‐14C]arachidonic and [3‐14C]docosa‐4,7,10,13,16‐pentaenoic acids was investigated after intratesticular injection of the labeled compounds and isolation of rat Sertoli and germinal cells. Following injection of either14C‐linoleate or14C‐arachidonate, the specific activity (sp act) of docosa‐4,7,10,13,16‐pentaenoic acid of Sertoli cells was greater than that of the germinal cells. The data suggest that the Sertoli cells are more active in the biosynthesis of the 22‐carbon pentaene than the germinal cells. Differences between these 2 cell types were also noted in the distribution of the incorporated14C among the various lipid classes. Following intratesticular injection of14C‐docosapentaenoic acid, a greater proportion of the recovered14C in Sertoli cells than in germinal cells was present in 20‐carbon fatty acids, suggesting a greater activity in Sertoli cells in the metabolism of the pentaene. The major portion of the recovered14C in both cell types was present in triacylglycerols during early time periods and in phospholipids after 24 hr. The possibility of transfer of biosynthesized docosapentaenoic acid from Sertoli to germinal cells is discussed.
Effect of plant sterols, fatty acids and lecithin on cholesterol absorption in vivo in the rat
Authors: Hollander Daniel , Morgan Donna 
Published: November 2006

AbstractThe inhibitory effect of plant sterols, fatty acids and lecithin on cholesterol intestnal absorption was studied in the unanesthetized rat using a single pass perfusion technique. Bile was excluded from the perfused intestine. Cholesterol absorption did not change following the additions of cholestanol, cholestanone, lanosterol, stigmasterol and β‐sitosterol. A 3‐fold increase in the molarity of cholestanol and β‐sitosterol or the separate additions of the saturated short and medium chain fatty acids, butyric and octanoic, also did not change cholesterol absorption. The unsaturated long chain fatty acids, oleic, linoleic, linolenic and arachidonic, inhibited cholesterol absorption. Lecithin additions at concentrations of 0.1–1.5 mM caused a progressive, dose‐related inhibition of cholesterol absorption. The inhibitory effect of these agents on cholesterol absorption is likely to have been caused by changes in cholesterol solubility in the micelle and shifts in the partition coefficient of cholesterol away from the cell membrane to the micelle.
Distribution of the phosphatidate phosphohydrolase activity in the lamellar body and lysosomal fractions of lung tissue
Authors: Okazaki Takeshi , Johnston John M. 
Published: November 2006

AbstractPhosphatidate phosphohydrolase (PAPase) activity was measured in lamellar bodies purified from porcine lung tissue. After repeated freeze‐thawing, only a negligible amount of PAPase activity was released into the soluble fractions, whereas there was release of 2 lysosomal marker enzyme activities, glucosaminidase and β‐galactosidase into the soluble fraction. In addition, a lysosomal‐enriched fraction was prepared from adult rat lung tissue by prior treatment of the rats with Triton WR 1339. Treatment with Triton WR 1339 resulted in the significant shift of the activities of the lysosomal marker enzymes, glucosaminidase and β‐galactosidase, to less dense subcellular fractions. The highest specific activity of PAPase was found in a subcellular fraction which had a density that was intermediate between that of the mitochondrial and microsomal fractions and the distribution of PAPase activity was not affected by the prior treatment of the rats with Triton WR 1339.
The structure of plasma low density lipoproteins: Experimental facts and interpretations—A minireview
Authors: Kirchhausen Tomas , Fless Gunther , Scanu Angelo M. 
Published: November 2006

AbstractFrom data on size and chemical composition, low density lipoprotein (LDL) can be described as a spherical particle having cholesteryl esters and triglycerides contained in a spherical core covered by the closely packed hydrophobic ends of phospholipids and unesterified cholesterol, while the head groups of the phospholipids, together with protein, occupy the surface. Such a model is compatible with early small angle X‐ray and neutron scattering studies which, by postulating spherical symmetry, assigned the LDL constituents to locations predicted from the radial electron density distribution. However, the concept of spherical symmetry, as applied to LDL structure, was recently challenged by results obtained from freeze‐etching electron microscopy and small angle X‐ray scattering experiments. Novel interpretations of these data suggest that the surface of LDL contains 4 electron‐dense globules, located at tetrahedral positions, which have a capacity for structural remodeling at least as a function of the 2 temperatures studied (21C and 41C). It is reasonable to presume that the LDL protein (apo LDL) plays a role in the organization of the surface and overall LDL structure. However, until the chemical properties of apo LDL, and its behavior in solution and at the water‐lipid interface are better understood, the validity of the proposed models cannot be assessed.
Alkenyl and alkyl ether phospholipids in pig mesenteric lymph node lymphocytes
Authors: Sugiura Takayuki , Masuzawa Yasuo , Waku Keizo 
Published: November 2006

AbstractSignificant amounts of alkenyl and alkyl ether phosphoglycerides were found in pig mesenteric lymph node lymphocytes. The choline phosphoglycerides are composed of 2.6% alkenyl ether and 25.7% alkyl ether compounds besides 71.7% diacyl analogs. The ethanolamine phosphoglycerides consist of 50.2% alkenyl ether, 7.8% alkyl ether and 42.0% diacyl compounds. The fatty chain compositions at the 1‐ and 2‐positions of each lipid class were analyzed.
Distribution of phosphoinositides among subfractions of rat brain myelin
Authors: Deshmukh D. S. , Kuizon S. , Bear W. D. , Brockerhoff H. 
Published: November 2006

AbstractRat brain myelin was separated into three subfractions, heavy, medium, and light, and the concentrations of phosphatidic acids (PA), phosphatidylinositol (PI), di‐ (DPI), and triphosphoinositide (TPI) in these fractions were determined. PI was evenly distributed among the fractions, and PA, DPI, and TPI occurred in highest concentrations in the “light” myelin. This result indicates that these fast metabolizing lipids play an important role in the tightly packed central lamellae of the myelin sheath.
Microsomal phosphatidic acid phosphohydrolase of rat mammary tissue: I. General properties
Authors: Tanaka K. , Kinsella J. E. 
Published: November 2006

AbstractThe microsomal bound phosphatidic acid phosphohydrolase from lactating rat mammary tissue had a specific activity of six nmoles per mg protein per minute. The optimum pH was 7.0; magnesium at 1.3 mM was required for maximum activity, and at low substrate concentrations magnesium lowered the Km of the enzyme for phosphatidic acid. Diglycerides exerted little effect while diglyceride ether stimulated enzyme activity. Inorganic salts, i.e., potassium phosphate and potassium chloride, enhanced rates of phosphatidic acid hydrolysis under standard assay conditions.
Identification of lipoxygenase‐linoleate decomposition products by direct gas chromatography‐mass spectrometry
Authors: St. Angelo A. J. , Legendre M. G. , Dupuy H. P. 
Published: November 2006

AbstractLipoxygenase, prepared from Virginia‐type peanuts, was used to catalyze the oxidation of linoleic acid and methyl linoleate to form the C−9 and C−13 hydroperoxides. These reactions were monitored by rapid unconventional direct gas chromatography‐mass spectroscopy. An aliquot of the enzymatic reaction mixture, without prior extraction or chemical modification, was secured directly into the heated (40–70 C) or nonheated (room temperature) injection system. When the reaction mixture was analyzed at room temperature, only hexanal was found. At elevated temperatures, five major and several minor components were identified. The predominant compounds identified were pentane, hexanal, 2‐pentylfuran,trans‐2,cis‐4‐decadienal, andtrans‐2,trans‐4‐decadienal. These products originate from decomposition of either the C−9 or C−13 hydroperoxides generated by peanut lipoxygenase.
Sterol composition of nystatin and amphotericin B resistant tobacco calluses
Authors: Chiu Pei‐Lu , Bottino P. J. , Patterson G. W. 
Published: November 2006

AbstractThe objective of this study was to select and characterize tobacco cell lines resistant to the polyene antibiotics Amphotericin B and Nystatin. Suspension culture cells of tobacco (Nicotiana tabacum L. ‘Wisconsin 38’) were treated with 0.025% ethyl methane sulfonate (EMS) and suspended in melted agar medium containing 0.005 mg/ml Amphotericin B. Cells were also irradiated with UV from a germicidal lamp and plated in the melted agar plating medium. After 6–10 days growth, the cultures were overplated with medium containing 750 u/ml Nystatin. All cultures were grown at 26 C in the dark. After three weeks, a single callus was isolated from the Amphotericin B treatment. This callus was subcultured, and would grow at concentrations of the antibiotic as high as 0.1 mg/ml (a 20‐fold increase over the selection concentration). Six callus lines were isolated from the Nystatin treatment. After subculture and transfer to media containing higher concentrations of Nystatin, only two calli survived and would grow at 1250 u/uml. Gas liquid chromatographic analysis of the resistant and control callus lines revealed similar sterol content among all the lines. However, when comparing total sterols produced, all three polyene resistant calluses contained significantly more sterols than the control. The Amphotericin B resistant calli produced about three times as much sterol as the controls, and the Nystatin resistant calli produced about 1.5 times as much sterol as the control. Both Nystatin resistant lines showed significant increases in stigmasterol. It appears that resistance of the three tobacco cell lines to these polyene antibiotics is due principally to varied amounts of overproduction of sterols rather than qualitative differences in sterols.
Effect of low methionine, choline deficient diets upon major unsaturated phosphatidyl choline fractions of rat liver and plasma
Authors: Lyman R. L. , Giotas C. , Medwadowski B. , Miljanich P. 
Published: November 2006

AbstractTo see how the metabolism of specific phosphatidyl choline fractions might be affected when only a limited source of methyl groups was available, rats were fed for 7 days a low methionine, cholinedeficient diet or one supplemented with either choline or methionine. Prior to killing, they were injected with14C‐methyl methionine and liver and plasma phosphatidyl choline isolated and separated by argentation chromatography into 3 major unsaturated fractions. Fatty acid composition and radioactivity of the fractions were determined. Deficient rats had reduced total liver phosphatidyl choline when compared with the supplemented groups, but the proportions of 20∶4 and 22∶6 fatty acids in the total phosphatidyl choline were unchanged. Plasma phosphatidyl choline also was reduced sharply by the deficiency, as was its proportion of 20∶4 fatty acid. Specific activities of the liver 22∶6, 20∶4, and 18∶2 phosphatidyl choline fractions showed that deficient rats had less radioactivity in their 20∶4 and 18∶2 phosphatidyl choline than did the supplemented animals. Plasma phosphatidyl choline fractions presented a similar pattern. Feeding methionine or choline nearly doubled radioactive methyl group incorporation into the 20∶4 phosphatidyl choline fraction of liver and plasma, while incorporation into the 22∶6 phosphatidyl choline was reduced or unchanged. The results suggested that, in the rat, limited availability of methyl groups altered the metabolism of liver and plasma phosphatidyl choline fractions. Methionine, as a source of labile methyl groups, appears necessary for the normal synthesis of certain unsaturated phosphatidyl choline fractions (particularly 20∶4 phosphatidyl choline). Transmethylation of phosphatidyl ethanolamine molecular species to the corresponding phosphatidyl choline species may be an important reaction in normal lipid metabolism and transport. Relative affinities for incorporation of the labeled methyl groups into the phosphatidyl choline fractions of either deficient or supplemented rats were: 22∶6>20∶4>18∶2.
Lipids of cultured hepatoma cells: VI. Glycerolipid and monoenoic fatty acid biosynthesis in minimal deviation hepatoma 7288C
Authors: Wiegand Rex D. , Wood Randall 
Published: November 2006

Abstract1‐14C‐Acetic, 1‐14C‐palmitic, or 1‐14C‐stearic acid was incubated with minimal deviation hepatoma 7288C cells grown in culture to assess: de novo fatty acid synthesis, oxidation, desaturation, and elongation of saturated fatty acids, as well as the ability of media fatty acids to serve as precursors of cellular glycerolipids. Distribution of radioactivity in the individual lipid classes and the various fatty acids of triglyceride, phosphatidyl choline, and phosphatidyl ethanolamine was determined. The radioactivity among the monoenoic acid isomers derived from triglyceride, phosphatidyl choline, and phosphatidyl ethanolamine was analyzed by reductive ozonolysis. Only small amounts of the labeled substrates were oxidized to carbon dioxide. Except for labeled stearic acid, which also was incorporated heavily into phosphatidyl inositol and phosphatidyl serine, most radioactivity was recovered in triglyceride, phosphatidyl choline, and phosphatidyl ethanolamine. Synthesis of cholesterol and long chain fatty acids from labeled acetic acid demonstrated that these cells can perform de novo synthesis of fatty acids and cholesterol. Both labeled palmitic and stearic acids were desaturated to the corresponding Δ9 monoenes, and palmitic and palmitoleic acids were elongated. The hexadecenoic acid fraction isolated from triglyceride, phosphatidyl choline, and phosphatidyl ethanolamine, when acetic or palmitic acid was the labeled substrate, showed that greater than 70% of the labeled acids were the Δ9 isomer. Radioactivity of the octadecenoic acid fraction derived from labeled acetic or palmitic acids was nearly equally divided between the Δ9 isomer, oleic acid, and the Δ11 isomer, vaccenic acid. Desaturation of labeled stearic acid produced only oleic acid. These data demonstrate that the biosynthesis of vaccenic acid in these cultured neoplastic cells proceeds via the elongation of palmitoleic acid. The relatively high level of vaccenic acid synthesis in these cells suggests that the reported elevation of “oleic acid” in many neoplasms may result from increased concentration of vaccenic acid.
Glycosphingolipids of fetal and adult sheep colonic mucosa
Authors: Dahiya Rajvir , Brasitus Thomas A. 
Published: November 2006

AbstractThe ganglioside and neutral glycosphingolipid composition of fetal and adult sheep colonic mucosa were characterized and compared. Mono‐ and tetrahexosylceramide were the major neutral glycolipids of both fetal and adult colons. Adult, but not fetal, mucosa also possessed di‐ and trihexosylceramide. Similarly, GD1a, GM3 and GM2 were found to be the principal gangliosides in fetal and adult tissue. Adult colonic mucosa possessed significant amounts of GT1a not present in fetal tissue.Analysis of the hydroxy and nonhydroxyfatty acids as well as of the long chain bases of the major glycosphingolipids revealed differences between these lipophilic components of glycolipids in fetal and adult colonic mucosa. The present results, therefore, indicate that both quantitative and qualitative differences in glycosphingolipid composition exist between fetal and adult sheep colonic mucosa.
Differential effects of lipoxygenase products on FMLP and LTB4 evoked neutrophil aggregation
Authors: Beckman Jeffrey K. , Gay James C. , Brash Alan R. , Lukens John N. , Oates John A. 
Published: November 2006

AbstractThere is evidence that the endogenous biosynthesis of LTB4 is involved in the aggregation of human neutrophils induced by the chemotactic peptide f‐met‐leu‐phe (FMLP). If LTB4 mediates this aggregatory response, then agents which desensitize neutrophils to LTB4 should inhibit the cellular response to FMLP. Since many lipoxygenase products modulate other neutrophil responses to LTB4 and FMLP, we have investigated the effects of lipoxygenase products on LTB4‐ and FMLP‐initiated aggregation.Prior exposure to low concentrations of LTB4 (0.5–10nM) inhibited subsequent aggregation to the same agent (50nM), but it did not influence the response to FMLP (10−7 M). Relatively high concentrations of 5‐HETE (5–50μM) inhibited aggregation initiated by either stimulus. Although the hydroperoxy derivative 5‐HPETE also inhibited the response to LTB4, in the relatively narrow concentration range of 1–4μM it stimulated FMLP‐induced aggregation. This latter effect was confirmed using 12 cell preparations from six separate donors; it (the activity of 5‐HPETE) was not mimicked by other 5‐lipoxygenase products, including LTB4, nor the dihydroperoxide 8,15‐DiHPETE. Our results indicate that neutrophil aggregation in response to LTB4 or FMLP can be selectively potentiated or inhibited. On the basis of these data we conclude that the endogenous synthesis of LTB4 is not directly involved in the neutrophil aggregatory response to FMLP, although the hydroperoxy intermediate 5‐HPETE may act to enhance the cellular response.
Elongation systems involved in the biosynthesis of erucic acid from oleic acid in developingBrassica juncea seeds
Authors: Agrawal Vishwanath P. , Stumpf Paul K. 
Published: November 2006

AbstractIn the presence of NADPH and malonyl‐CoA, the cell‐free extract of developingBrassica juncea seeds catalyzes the elongation of14C‐oleoyl‐CoA to radioactive C20∶1 and C22∶1. The elongation of C18∶1 to C20∶1 shows no marked preference for NADPH or NADH. On the other hand, the elongation of C20∶1 to C22∶1 exhibits a pronounced preference for NADPH. Moreover, the latter elongation system (C20∶1→C22∶1) is more sensitive to inhibition by trichloroacetate and sodium metabisulfite. Inclusion of polyvinylpolypyrrolidone in the grinding buffer for preparation of the cell‐free extract enhances the elongation activity by 5–6 fold.14C‐Stearoyl‐CoA, but not14C‐palmitoyl‐CoA, also is elongated by this system. The results presented here suggest certain degrees of dissimilarity between the first (C18∶1→C20∶1) and second elongation (C20∶1→C22∶1) systems.
Modification of alkenyl chain profile in plasmalogens of rat heart mitochondria by dietary trielaidin
Authors: Wolff Robert L. , Combe Nicole A. , Entressangles Bernard 
Published: November 2006

AbstractEffects of dietary trielaidin upon the alkenyl chain profile of plasmalogens were studied using heart mitochondria of rats fed a semi‐purified diet containing 10% of fat supplement in which elaidic acid accounted for 69% of total fatty acids. Alkyl substituted dioxane (ASD) derivatives of the alkenyl groups of plasmalogens were prepared and analyzed by silver nitrate TLC and by GLC on different phases (BDS and OV‐275). After two months of feeding the experimental diet, 40% of the ASD contained atrans‐octadecenyl chain, suggesting that dietary elaidic acid was reduced in vivo to the corresponding alcohol and incorporated into plasmalogens. There was a simultaneous decrease in the percentage of ASD containing saturated chains, but the percentage of ASD substituted withcis‐octadecenyl chains was not significantly affected. These observations suggested that elaidic acid may compete with saturated fatty acids, but not withcis‐octadecenoic acids during the plasmalogen biosynthesis. Feeding trielaidin did not seem to have any significant influence on the relative proportions of plasmalogens, which accounted for 11–12%, on a phosphorus basis, of total heart mitochondria phospholipids.
Inhibition of acyl CoA: Cholesterol acyltransferase and sterologenesis in rat liver by diazepam,In vitro
Authors: Bell Frank P. 
Published: November 2006

AbstractDiazepam, a commonly prescribed tranquilizer, was found to inhibit cholesterol biosynthesis in rat liver minces; inhibition appeared to occur at multiple post‐mevalonate sites. Diazepam also inhibited cholesterol esterification by acylCoA:cholesterol acyltransferase in isolated liver microsomes and minces. Liver minces incubated with [14C] oleate demonstrated increased uptake of the fatty acid and a greater incorporation of the substrate into triglycerides, diglycerides and phospholipids when diazepam was present. The results suggest possible mechanisms for the hypocholesterolemic effect of diazepam in experimental animals and for the elevation of triglycerides and very low‐density lipoproteins in man and the rat.
Effect of KCD‐232, a new hypolipidemic agent, on serum lipoprotein changes in hepatoma‐bearing rats
Authors: Irikura T. , Takagi K. , Okada K. , Yagasaki K. 
Published: November 2006

AbstractChanges in serum lipoprotein profiles were characterized in Donryu rats subcutaneously implanted with an ascites hepatoma line of AH109A cells and the effect of a new hypolipidemic agent with a structure of 4‐(4′‐chlorobenzyloxy)benzyl nicotinate (KCD‐232) was estimated. With the growth of hepatoma for periods of up to three weeks, a striking decrease in the high density lipoprotein (HDL) fraction and an enormous increase in the VLDL+LDL (very low density lipoprotein+low density lipoprotein) fraction were found in hepatoma‐bearing rats when either precipitation method or electrophoresis was used. These lipoprotein profiles were not influenced by sex. Judging from the electrophoretogram, the increase in VLDL+LDL fraction was due mainly to an increase in LDL fraction. The oral administration of KCD‐232 significantly suppressed the hepatoma‐induced increase in VLDL+LDL with little or no influence on the hepatoma‐induced decrease in HDL. There existed a positive correlation between the hepatoma weight and (VLDL+LDL)‐cholesterol concentration and a negative one between hepatoma and HDL‐cholesterol.