bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biosynthesis of fatty acids by the carp,Cyprinus carpio L., in relation to environmental temperature
Authors: Farkas Tibor , Csenger Istvan 
Published: December 2006

AbstractIncorporation in vivo of sodium 1‐14C‐acetate into different lipid classes and fatty acids of total lipids and phospholipids of warm adapted and cold adapted carp livers was studied at 5 C and 22 C, respectively. The fatty acid composition of total lipids and phospholipids was also determined. The level of long chain polyunsaturated fatty acids in both total lipid and phospholipid fractions was higher in cold adapted fish than in warm adapted ones. The distribution of radioactivity among different lipid classes depended only on the actual incorporation temperature and was independent of the temperature history of the animals. Livers of fish incorporated a higher percentage of radioactivity into long chain polyunsaturated fatty acids of total lipids and phospholipids in 5 C than in 22 C. The distribution of radioactivity among different fatty acids was dependent on the experimental temperature rather than on the temperature to which the fish were adapted. The results suggest that fish are able to adjust the pattern of the biosynthesis of fatty acids very rapidly to the prevailing temperature and to assure by this way the proper physicochemical properties of their membranes. The possible mechanisms involved in this rapid response are discussed.
Mass spectra of acetylenic fatty acid methyl esters and derivatives
Authors: Kleiman R. , Bohannon M. B. , Gunstone F. D. , Barve J. A. 
Published: December 2006

AbstractA series of isomeric methyl octadecynoates was analyzed by mass spectrometry; each isomer gave a unique spectrum. The characteristic ions were those resulting from a McLafferty rearrangement of the allenic sites or of the already‐rearranged allenic sites. The acetylenic esters were also subjected to oxymercuration whereupon a carbonyl group was formed at either of the original actylenic carbon atoms providing two oxostearates. Further reaction with NaBH4 formed hydroxy esters which, after silylation, gave diagnostic mass spectra indicative of the triple bond location. Applied to esters with both double and triple bonds, this procedure permitted differentiation between the two types of unsaturation. Methoxyl groups marked the original double bond locations and hydroxyls did so for triple bonds.
Kinetics of absorption, equilibration (or distribution), and excretion of orally and intraperitoneally administered cholesterol in the rat
Authors: Adam A. , Van Cantfort J. , Gielen J. 
Published: December 2006

AbstractResorption and metabolism of cholesterol administered intraperitoneally and per os have been described in the rat utilizing a technique of double isotopic labeling. Depending upon the route of administration, these parameters vary to a large degree. Alimentary cholesterol is progressively resorbed over a period of 10 hr, while the maximal blood level of cholesterol is attained after the 6th hr following intraperitoneal injection. On the other hand, cholesterol administered per os is more rapidly utilized in biliary acid synthesis than cholesterol administered intraperitoneally. In the range of concentrations utilized in this work (10–300 μg and 0.2–300 μg, respectively, administered to the rat, orally and intraperitoneally), the rate of cholesterol resorption remained constant.
Studies on drug‐induced lipidosis: VII. Effects of bis‐β‐diethylaminoethylether of hexestrol, chloroquine, homochlorocyclizine, prenylamine, and diazacholesterol on the lipid composition of rat liver and kidney
Authors: Yamamoto Akira , Adachi Susumu , Matsuzawa Yuji , Kitani Teruo , Hiraoka Akira , Seki Ko‐Ichi 
Published: December 2006

Abstract4,4′‐Bis (β‐diethylaminoethoxy)‐α,β‐diethyldiphenylethane (DH), which had been shown to induce a type of lipidosis resembling Niemann‐Pick disease, was given to rats at a dose of 20, 50, 100, and 150 mg/kg body weight per day for 1 or 2 weeks. An enlargement of the liver with marked increases in free cholesterol, total phospholipids, and phosphatidylinositol took place by administration of a larger dose. The increase in bis (monoacylglyceryl) phosphate (BMGP), which is peculiar to this kind of drug‐induced lipidosis, was dependent upon the dose of the drug as well as the length of time. Similar changes were also observed in kidney. Among several other drugs tested, chloroquine and diazacholesterol brough on as much increase in BMGP as treatement with DH.
A study of the heparin‐manganese chloride method for determination of plasma α‐lipoprotein cholesterol concentration
Authors: Ishikawa T. T. , Brazier J. B. , Steiner P. M. , Stewart L. E. , Gartside P. S. , Glueck C. J. 
Published: December 2006

AbstractTo assess the limits of the heparin‐MnCl2 precipitation method for quantitation of α‐lipoprotein cholesterol (C‐HDL), effects of varying final MnCl2 and heparin concentrations were studied, and the precipitation method was compared to preparative ultracentrifugation. In 65 parallel plasma aliquots, C‐HDL determined by ultracentrifugation (54.3±1.8 mg/dl) correlated significantly (r=0.98, P<0.001) with the precipitation method (56.0±1.9 mg/dl). C‐HDL by ultracentrifugal and precipitation methods were also similar in 16 subjects with triglycerides ranging from 150 to 312 mg/dl (41.4±2.6, 43.4±2.8, r=0.97, P<.001). A constant amount of cholesterol in the supernatant was measured over a final MnCl2 range of 0.046–0.23M, and cholesterol values in the supernatant at final MnCl2 concentrations of 0.046, 0.05, and 0.055M did not differ from each other, P>0.1. However, cholesterol levels in the supernatant at final MnCl2 concentration of 0.042M differed from those at concentrations of 0.046, 0.05, and 0.055M, P<0.05, and the amount of supernatant cholesterol increased as the final MnCl2 concentration was reduced from 0.042 to 0.02M. A constant amount of cholesterol in the supernatant was measured over a heparin concentration range of 92–734 USP units/ml. The final MnCl2 and heparin concentrations of 0.046M and 184 USP units/ml, which are incorporated in widely used procedures, gave C‐HDL values for the precipitation method which were in close agreement with the ultracentrifugal method. There is no evidence for a heparin‐Mn++ precipitation of HDL and systematic underestimation of HDL by the precipitation method. However, the final MnCl2 concentration is very near the minimum required for accurate measurement of C‐HDL. To preclude incomplete precipitation of low and very low density lipoproteins by insufficient manganese concentration, an increase of the manganese concentration should be considered.
Fecal long chain fatty acids and colon cancer risk
Authors: Sperry J. F. , Salyers A. A. , Wilkins T. D. 
Published: December 2006

AbstractTo determine whether excretion of high concentrations of long chain fatty acids might be associated with high colon cancer risk, we compared concentrations of major long chain fatty acids in the feces of four populations at different risk for colon cancer. Concentrations of C18∶1 were found to be significantly higher (P<0.05) in the feces of the two high risk populations than in the feces of the two low risk populations.
Binding of squalene, lanosterol, desmosterol, and cholesterol to proteins in brain and liver 105,000 g supernatant fractions: Evidence for specific binding sites
Authors: Johnson Ronald C. , Shah Shantilal N. 
Published: December 2006

AbstractThe binding of squalene, lanosterol, desmosterol, and cholesterol to proteins in 105,000 g supernatant fraction (S105) from brain and liver of rats was investigated. The S105 fractions from both tissues contain specific binding sites for sterols, which are sensitive to trypsin. The dissociation constants for squalene and sterol protein complexes were in the range of 10−6 M and were not appreciably different for proteins in brain and liver S105. Competition studies revealed that both brain and liver S105 contain one receptor protein which binds lanosterol and is specific for methyl sterols, and a second receptor which binds both desmosterol and cholesterol. Binding of 7‐dehydrocholesterol reported by others must occur at a third independent site since this compound does not interfere with the binding of lanosterol, desmosterol, or cholesterol. Although binding of squalene to proteins in brain and liver S105 does occur, we were unable to show the specificity of squalene binding. The concentration of desmosterol and cholesterol binding sites, which ranged from 6 to 10 nmol/mg protein, was 3‐ to 5‐fold higher than the concentration of squalene and lanosterol binding sites (1.6–2.3 nmol/mg protein). The brain S105 from suckling rats contained fewer binding sites for desmosterol and cholesterol than the brain S105 from weaned rats. However, the concentration of lanosterol binding sites in brain S105 did not show an age‐dependent change. The receptor proteins in brain and liver appear to be identical.
Effects of rapeseed oil on fatty acid oxidation and lipid levels in rat heart and liver
Authors: Galli Kienle M. , Cighetti G. , Spagnuolo C. , Galli C. 
Published: December 2006

AbstractThe comparative rates of oxidation of erucic and oleic acids and of their CoA esters were studied in heart and liver mitochondria of rats fed a standard diet or semisynthetic diets containing 25% of the calories as either rapeseed oil (46.6% erucic and 10.4% eicosenoic acid) or olive oil, for a period of 5 months. The long exposure to the diet containing 25% rapeseed oil did not alter the oxidative activity of mitochondria and did not induce morphological changes in the heart. It is confirmed that erucic acid is oxidized in mitochondria at lower rates than other long chain fatty acids and that its activation as CoA derivative may be one of the rate limiting steps of the overall oxidation process. Total lipids and triglycerides do not significantly change in the heart whereas they increase in the liver of rats fed the diet containing rapeseed oil.
Monoacyl‐sn‐glycerol 3‐phosphate acyltransferase specificity in bovine mammary microsomes
Authors: Kinsella John E. 
Published: December 2006

AbstractThe acyl‐CoA∶:acyl‐sn‐glycerol 3‐phosphate acyltransferases located in the microsomal fraction of lactating bovine mammary tissue show a preference for palmityl‐CoA particularly above the apparent Km values of the acyl acceptors. Using saturating levels of monopalmityl‐sn‐glycerol 3‐phosphate, the order of acylation was palmityl‐>myristyl‐> oleyl‐>stearyl‐>linoleyl‐CoA. Apparent Km values for monopalmityl‐ and monooleyl‐sn‐glycerol 3‐phosphate with palmityl‐CoA as donor were 16 and 13μM, respectively, while the Km values for palmityl‐CoA with these two acyl acceptors were 5 and 5.2μM, respectively. The apparent Vmax values for the palmityl acceptor and donor were 25 and 30 nmol/min/mg protein. Phosphatidic acid was the principal product. The inclusion of magnesium in the assay depressed activity while the addition of ethylenediaminetetraacetate doubled the rate of acylation.
Occurrence of 2‐ and 3‐hydroxy fatty acids in high concentrations in the extractable and bound lipids ofFlavobacterium meningosepticum andFlavobacterium IIb
Authors: Yano I. , Ohno Y. , Masui M. , Kato K. , Yabuuchi E. , Ohyama A. 
Published: December 2006

AbstractThe major hydroxy fatty acids of cellular lipids inFlavobacterium meningosepticum andFlavobacterium sp. King's group IIb were identified as 2‐hydroxy 13‐methyltetradecanoic, 3‐hydroxy 13‐methyltetradecanoic, 3‐hydroxy palmitic, and 3‐hydroxy 15‐methylhexadecanoic acids using gas chromatography‐mass spectrometry and GC‐mass fragmentography. The concentration of these hydroxy fatty acids comprised up to 30–40% of the total extractable and 20–30% of the bound lipid fatty acids, respectively. From the stability for mild alkaline hydrolysis, 2‐hydroxy fatty acids seemed to be attached with ester linkage, and 3‐hydroxy fatty acids with amide linkage.
Biosynthesis of polyunsaturated fatty acids in the developing brain: II. Metabolic transformations of intracranially administered [3‐14C] eicosatrienoic acid, evidence for lack of Δ8 desaturasedesaturase
Authors: Dhopeshwarkar Govind A. , Subramanian Carole 
Published: December 2006

Abstract[3‐14C] Eicosatrienoic acid (Δ11,14,17) chemically synthesized from [1‐14C] linolenic acid was injected intracranially into 14‐day old rats and sacrificed 8 hr later. The analysis of brain fatty acids by radio‐gas liquid chromatography before and after ozonolysis showed that the tetraene fraction consisted of a desaturated product, Δ5,11,17–20∶4, and its elongated product, Δ7,13,16,19–22∶4. Both of these products, with a combined total of 61% of the total radioactivity recovered in the tetraene fraction, contain a nonmethylene interrupted double bond system and, therefore, are unsuitable for further desaturation. The other two components, Δ6,9,12,15–18∶4 and Δ8,11,14,17–20∶4, must have been formed from Δ9,12,15–18∶3, formed by retroconversion of the starting material 20∶3, followed by desaturation and elongation. These results suggest a lack of Δ8 desaturase in the developing brain, leading to formation of Δ5,11,14,17–20∶4 rather than Δ8,11,14,17–20∶4. Howeve, the nonmethylene interrupted double bond isomer does not restrict chain elongation.
Lipid synthesis by perfused lung
Authors: Tombropoulos Elias G. , Hadley John G. 
Published: December 2006

AbstractAn isolated lung ventilated with pulses of negative pressure and perfused through the pulmonary vasculature was utilized for the study of 3‐sn‐phosphatidylcholine synthesis. The perfusion fluid consisted of a Krebs‐Ringer phosphate buffer with 6% bovine serum albumin, pH 7.4, and the appropriate substrate. The simultaneous incorporation of (1‐14C) palmitate and (2‐3H) glycerol and the simultaneous incorporation of (CH3‐14C) choline and (CH3‐3H) methionine were examined. From these experiments it is concluded: 1) lung tissue incorporates (2‐3H) glycerol into 3‐sn‐phosphatidylcholine to a greater extent than any other lipid examined; 2) both choline and methionine contribute to the synthesis of 3‐sn‐phosphatidylcholine, and 50–70% of the label in its nitrogen base is derived from choline and 30–50% from methionine; and 3) a high PO2 appears to reduce the synthesis of 3‐sn‐phosphatidylcholine.
Cardiopathogenicity of rapeseed oils and oil blends differing in erucic, linoleic, and linolenic acid content
Authors: McCutcheon J. S. , Umermura T. , Bhatnagar M. K. , Walker B. L. 
Published: December 2006

AbstractMale Wistar rats were fed semipurified diets containing 20% fat for 25 weeks. Ten different oils or oil blends were employed, including rapeseed oils, simulated rapeseed‐type oils, and modified rapeseed‐type oils. Safflower, soybean, and hydrogenated coconut oils served as control oils. Histopathological examination of the cardiac tissue was conducted at the end of the study and an incidence‐severity rating assigned to the lesions induced by each fat. Oils containing high levels of erucic acid (26–30%) induced the most severe cardiac necrosis, irrespective of the source of erucic acid (rapeseed oil or nasturtium oil). Increasing the linoleic: linolenic acid ratio of the high erucic oils to that of soybean oil failed to reduce necrosis, but the absence of linolenic acid from a high erucic acid oil blend resulted in a markedly reduced lesion incidence‐severity rating, comparable to those obtained for low erucic acid rapessed oil and soybean oil which were similar. Lowest lesion incidence was obtained with safflower oil and hydrogenated coconut oil. We have postulated that linolenic acid plays a role in the etiology of cardiac necrosis observed when rats are fed diets containing low erucic acid rapeseed oils.
Effect of cholesterol and cholestyramine feeding and of fasting on sterol synthesis in the liver, ileum, and lung of the guinea pig
Authors: Turley S. D. , West C. E. 
Published: December 2006

AbstractThe effects of feeding diets containing either cholesterol (0.24% w/w) or cholestyramine (2.5% w/w) and of fasting on sterol synthesis in the liver, ileum, and lung of both male and female guinea pigs have been studied by measuring the incorporation by tissue slices of14C‐labeled acetate into total digitonin‐precipitable sterols. Cholesterol feeding significantly decreased (P<0.05) sterol synthesis in the liver, ileum, and lung of the males and in the ileum of females. Cholestyramine feeding stimulated the rate of hepatic sterol synthesis 13‐fold but did not significantly affect sterologenesis in the ileum. Sterol synthesis in the lung was significantly increased (P<0.05) but to a much lesser extent than in the liver. Fatty acid synthesis in the liver, ileum, and lung was not significantly affected by either cholesterol or cholestyramine feeding. In guinea pigs fasted for 24 hr, sterol synthesis was inhibited in all three tissues, the most pronounced effect occurring in the liver. Only in the lung was fatty acid synthesis significantly decreased (P<0.001) by fasting. Cholesterol feeding resulted in increased concentrations of cholesterol in the plasma and liver. Cholestyramine feeding reduced plasma cholesterol concentration by 81% in females and by 64% in males. However, it did not significantly change the tissue cholesterol concentrations. Fasting resulted in a significant increase (P<0.05) in plasma cholesterol concentration but did not affect the concentration of cholesterol in the tissues. It was concluded that in the normal guinea pig, the feedback inhibition produced by both cholesterol and also possibly by bile acids suppresses sterol synthesis in the liver to very low rates compared to those in the small intestine, where sterologenesis is not only less sensitive to the cholesterol negative feedback system than that in the liver, but also is not subject to regulation by the bile acid negative feedback system.
Initial cholesterol uptake by everted sacs of rat small intestine: Kinetic and thermodynamic aspects
Authors: Chow San‐Laung , Hollander Daniel 
Published: December 2006

AbstractThe kinetics of initial cholesterol uptake by everted rat proximal and distal small intestinal sacs were evaluated in vitro. The mucosal incubation solution consisted of 0.05 mM cholesterol solubilized in 4.8 mM sodium taurocholate micellar solution at pH 7.4. Experiments were performed at temperatures from 26 to 38 C. The rate of cholesterol uptake followed a linear relationship when plotted against time indicating an apparent zero‐order kinetics mechanism for initial uptake. An Arrhenius plot of the results of uptake versus temperature remained linear over the entire range of temperatures studied. The large free energy of activation (20 kcal/mole) suggests that an energy barrier for cholesterol uptake exists at the enterocyte luminal cell membrane and may be an important limiting step in cholesterol uptake. It is proposed that a transient association between cholesterol and a component of the enterocyte luminal cell membrane is formed during initial uptake of cholesterol. The transient association may be an activated complex formed with proteins present at or within the luminal enterocyte cell membrane.
The effects of certain ecdysteroids and inhibitory amines and amides on the metabolism of 22,25‐dideoxyecdysone in cockroach organ cultures
Authors: Marks Edwin P. , Robbins William E. , Thompson Malcolm J. 
Published: December 2006

AbstractAn organ culture assay system using cockroach leg regenerates and fat body has been developed in which compounds that either inhibit molting hormone metabolism or act as molting hormone antagonists can be tested. Representatives of three classes of compounds were tested in the system: ecdysteroids, azasteroids, and nonsteroidal amines and amides. Inhibitory compounds were found in all three of the classes. Certain of these inhibitors represent a new class of insect hormonal compounds with a novel mode of action—the disruption of molting hormone metabolism.
Steric requirements for the stimulation of glycosyltransferase activity by lysophosphatidylcholine
Authors: O'Doherty P. J. A. 
Published: December 2006

Abstract1‐Palmitoyl‐sn‐glycerol‐3‐phosphocholine and 3‐palmitoyl‐sn‐glycerol‐1‐phosphocholine have been found to be equipotent in the stimulation of membrane‐bound glycosyltransferases in microsomes of rat intestinal villus cells. This indicates that the stimulatory effect of lysophosphatidylcholine is not stereospecific, but that it may be related to a specific detergent property dependent upon the peculiar balance of hydrophilic and hydrophobic components in the molecule.
Prostaglandin metabolism by human testis
Authors: Carpenter M. P. , Robinson R. D. , Thuy L. P. 
Published: December 2006

AbstractHuman testis preparations appear to carry out both the synthesis and turnover of prostaglandins. Prostaglandins and prostaglandin metabolites were extracted from whole tissue. Testis microsomes converted both endogenous and exogenous substrate to prostaglandins. Microsomal prostaglandin biosynthesis was inhibited by indomethacin. Prostaglandin E2‐9‐ketoreductase was present in both the cytosolic and microsomal fractions of human testis. Prostaglandin metabolism by human testis has not previously been reported.
Factors affecting fatty acid oxidation in bovine mammary tissue
Authors: Dimenna G. P. , Emery R. S. 
Published: December 2006

AbstractOxidation of fatty acids was studied in bovine mammary tissue slices in order to evaluate their potential contribution to energy metabolism. Rates of fatty acid oxidation decreased with increasing chain length: acetate>octanoate>palmitate or oleate. Rates of oxidation of long chain, but not short chain, fatty acids increased over time, which could not be explained by carnitine palmitoyltransferase (CPT) activity. This phenomenon is not an artifact of the incubation system or caused by substrate solubility, as rates of palmitate oxidation were constant in rat kidney cortex slices. Preincubating mammary tissue with or without unlabeled palmitate showed that increasing rates of palmitate oxidation is not caused by use of endogenous fatty acids. Palmitate at 0.26 mM, equivalent to arterial fatty acid concentration, gave maximal rates of oxidation. The β‐oxidation enzymes may restrict fatty acid oxidation as oxidation of [1‐14C] palmitate exceeded that of [U‐14C] palmitate. Acetate inhibited palmitate oxidation (75%) but not esterification, suggesting that acetate inhibits palmitate oxidation by substrate competition at the mitochondrial level or via malonyl‐CoA inhibition of CPT. Glucose inhibited palmitate oxidation (67%) and stimulated esterification. Low palmitoyl‐CoA levels would favor glyceride synthesis over oxidation, since the apparent Km for palmitoyl‐CoA, of the glycerol‐3‐phosphate acyltransferases is lower than that for CPT. Thus, glucose presumably diverts palmitate from oxidation to glycerolipids. Clofenapate, a glyceride synthesis inhibitor, decreased triacylglycerol formation, and marginally increased palmitate oxidation. We estimated that long chain fatty acids can potentially account for 6–10% of the oxidative metabolism of mammary tissue.