bluuebunny/crossref_metadata_2025_split huggingface dataset:
An improved procedure for bile acid extraction and purification and tissue distribution in the rat
Authors: Locket Patricia L. , Gallaher Daniel D. 
Published: November 2006

AbstractTwo bile acid extraction procedures were compared using endogenously radiolabeled tissues and feces. The method of Setchell et al. (J. Lipid Res. 24, 1085–1100, 1983) resulted in essential complete extraction, whereas that of Manes and Schneider (J. Lipid Res. 6, 376–377, 1971) gave recoveries between 56–82%. The time requirement for the method of Setchell et al. could be drastically reduced with no loss in extraction efficiency. Using extracts from endogenously labeled material, a purification procedure using C18 solid‐phase extraction cartridges was developed that recovers >90% of bile acids. The distribution of bile acids within the intestinal tract and liver of the rat was determined.
Comparative study of methods for measuring cholesterol in biological fluids
Authors: Cheillan Franck , Lafont Huguette , Termine Elise , Hamann Yolande , Lesgards Guy 
Published: November 2006

AbstractA method combining enzymatic and electrochemical detection of cholesterol in biological fluids was compared with conventional detection methods: two chromatographic methods—gas chromatography or high performance liquid chromatography—and two enzymatic methods with colorimetric detection either by kinetic measurement or at the end of the reaction. For serum, enzymatic determination is accurate with both colorimetric detection methods; but for bile, colorimetric detection is difficult to perform due to interference from bile pigments. Enzymatic cholesterol determination, combined with electrochemical detection, is simpler and gives results in good agreement with those of chromatographic methods.
Very low density lipoprotein secretion by cultured hepatocytes of rabbits fed purified or autoxidized cholesterol
Authors: Kosykh Vladimir A. , Lankin Vadim Z. , Podrez Eugeniy A. , Novikov Dmitriy K. , Volgushev Sergey A. , Victorov Alexander V. , Repin Vaddim S. , Smirnov Vladimir N. 
Published: November 2006

AbstractThe main objectives of this study were to compare the effects of dietary commercial cholesterol (containing 5% of oxidized cholesterol derivatives) and purified cholesterol on the secretion rate of very low density lipoprotein apolipoproteins and lipids by cultured rabbit hepatocytes and to verify the hypothesis that products of cholesterol autoxidation stimulate the rapid development of hypercholesterolemia. Rabbits fed dietary (old) commercial cholesterol for six weeks showed a fivefold increase in the serum concentration of cholesterol compared with that in purified cholesterol‐fed rabbits. The secretion rates of very low density lipoprotein total protein and very low density lipoprotein [3H]apolipoproteins were similar for the hepatocytes of these two cholesterol‐fed groups of animals and were two‐ and threefold greater, respectively, than for cells from control rabbits. Cholesteryl ester content of the hepatocytes from dietary (old) commercial cholesterol‐fed rabbits was dramatically increased in comparison with hepatocytes from control and purified cholesterol‐fed rabbits. The elevated intracellular cholesteryl ester content is assumed to account for such an increase of very low density lipoprotein‐cholesteryl ester secretion by cells prepared from dietary (old) commercial cholesterol‐fed rabbits. These effects appear to be caused by activation of cholesterol esterification by oxidized cholesterol derivatives. The rapid development of hypercholesterolemia induced by dietary (old) commercial cholesterol is associated, at least in part, with the stimulated production of hepatic very low density lipoprotein apolipoproteins and cholesteryl esters.
Effect of marginal zinc deficiency on lipoprotein lipase activities in postheparin plasma, skeletal muscle and adipose tissues in the rat
Authors: Koo Sung I. , Lee Christine C. 
Published: November 2006

AbstractThe activities of lipoprotein lipase in postheparin plasma, retroperitoneal adipose and gastrocnemius muscle tissues were determined in the rats fed 2.8 ppm of dietary zinc for eight weeks, as compared with pair‐fed and ad libitumfed rats given 30.8 ppm of zinc. The postheparin lipoprotein lipase activity, as determined by using a lipid emulsion labeled with [3H]triolein as the substrate, was significantly lower in the first group of rats, relative to that in the second and third groups. Tissue lipoprotein lipase activities were compared using the lipid emulsion and activator serum obtained from the zinc‐deficient rats and the ad libitum‐fed rats. The activator sera were devoid of very low density and low density lipoproteins, but enriched in high density lipoproteins. Muscle lipoprotein lipase activities were significantly lower when assayed with the activator serum from the zinc‐deficient compared with the activities determined with the activator serum from the ad libitum‐fed. Similarly, muscle lipoprotein lipase activities were lower in all groups when [3H]‐triolein‐labeled chylomicrons from the zinc‐deficient were used as the substrate, compared with the activities determined using the chylomicrons from the ad libitum‐fed. Lipoprotein lipase activities in the adipose tissues were not affected by the different sources of the activator sera and chylomicrons. The results strongly suggest that the decrease in postheparin lipoprotein lipase activity in zinc deficiency is not due to changes in tissue lipoprotein lipase enzyme per se, but to compositional alterations in with regard to C apolipoproteins, modulators of lipoprotein lipase activity.
Bradykinin‐increased phospholipid deacylation‐reacylation in rat renal medulla is inhibited by dBc AMP
Authors: Sterin‐Speziale Norma , Kahane Verónica L. , Setton Clara P. , Speziale Emir H. 
Published: November 2006

AbstractThe effect of bradykinin on the mobilization of arachidonic acid was analyzed separately by acylation and degradation.Acylating activity was determined by the incorporation of [14C]arachidonic acid into the phospholipids at different times. Different concentrations of bradykinin had no effect on the phospholipid acylating activities.The degradation of the phospholipids was performed on renal medullary slices prelabeled with [14C]arachidonic acid. Treatment with bradykinin produced an initial degradation of phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol, with a concomitant increase in lysophosphatidylcholine, lysophosphatidylethanolamine and lysophosphatidylinositol within 5 min of incubation. Phosphatidylcholine‐, phosphatidylethanolamine‐and phosphatidylinositol‐labeling increased thereafter and reached the control values after 10 min of incubation.After 30 min, incubation of prelabeled slices with bradykinin produced a significant concentration‐dependent increase in the phospholipid‐labeling by reutilization of [14C]arachidonic acid.The effect of bradykinin on the phospholipid‐labeling was blocked by preincubation with increasing concentrations of dBc AMP.Mepacrine also blocked the bradykinin stimulation in phosphatidylcholine and phosphatidylethanolamine, but had no effect on bradykinin‐induced changes in the phosphatidylinositol arachidonic acid moiety.
Dietary induction of cholesterol gallstones in hamsters from three different sources
Authors: Cohen Bertram I. , Matoba Naoyuki , Mosbach Erwin H. , McSherry Charles K. 
Published: November 2006

AbstractCholesterol gallstones were produced in young male, golden Syrian hamsters, obtained from three different suppliers, by administering a nutritionally adequate, semipurified diet for periods of either 5 or 10 weeks. The major components of the lithogenic diet were casein, cornstarch, butterfat, corn oil and 0.3% cholesterol. The hamsters were obtained from Sesco, Harlan Sprague‐Dawley (Engle hamster) and Charles River (Lakeview hamster). There were profound differences among the three groups with respect to gallstone formation and cholesterol metabolism: The highest incidence of gallstones occurred in Sesco hamsters, 44.4% and 63.6% after 5 and 10 weeks on the lithogenic diet, respectively. In the Engle hamster, after a 5‐week feeding, cholesterol crystals and gallstones were absent. When the feeding period was extended to 10 weeks, cholesterol gallstones were present in 45.5% of the animals. In the Lakeview hamsters, neither gallstones nor cholesterol crystals were found in the gallbladder after a 5‐week period. After 10 weeks, cholesterol gallstones were found in only a single hamster. In all groups, the lithogenic diet produced large increases of liver, serum and biliary cholesterol concentrations and increased liver weights. When the animals were fed for 5 weeks, only the bile of Sesco hamsters became supersaturated. Supersaturated bile was induced in all groups after a 10‐week feeding of the lithogenic diet with cholesterol saturation ranging from 1.47 to 1.97. These data indicate that it is possible to induce cholesterol gallstones in hamsters by means of a nutritionally adequate, semipurified diet of moderate cholesterol content. The source of the animals appears to be an important variable, because there were significant differences among the hamsters of differing origins, in cholesterol metabolism and rates of gallstone formation.
Determination of ethane and pentane in free oxygen radical‐induced lipid peroxidation
Authors: Pitkänen O. M. , Hallman M. , Andersson S. M. 
Published: November 2006

AbstractIt has been proposed that ethane and pentane reflect free oxygen radical‐induced lipid peroxidation. However, methodological difficulties limit the use of these gases for assessment of free oxygen radical activity. In the present report we describe an improved method for the accurate analysis of picomole quantities (≥1 pmol) of ethane and pentane. They are first quantitatively trapped into an adsorbent and then heat‐desorbed directly into a capillary column for gas chromatographic quantitation. During oxidation of linolenic (n−3) and linoleic (n−6) acid, ethane and pentane were formed, respectively. Nonstimulated granulocytes formed pentane. Upon addition of phorbol 13‐myristate 12‐acetate, the generation of pentane was increased by 540%. Addition of superoxide dismutase plus catalase inhibited lipid peroxidation in both a cell‐free system and in isolated cells.The present method is useful in the evaluation of free oxygen radical induced damage.
Effect of sitosterol on the rate‐limiting enzymes in cholesterol synthesis and degradation
Authors: Boberg Kirsten Muri , Åkerlund Jan‐Erik , Björkhem Ingemar 
Published: November 2006

AbstractAttempts were made to develop an animal model for phytosterolemia. Infusion of Intralipid containing 0.2% sitosterol in rats gave circulating levels of sitosterol of about 2.5 mmol/l, which is similar to or higher than those present in patients with untreated phytosterolemia. In addition, the infusions gave serum levels of cholesterol nearly twice those obtained in rats infused with Intralipid alone or Intralipid containing 0.2% cholesterol. The hepatic HMG‐CoA reductase activity was unaffected or slightly increased by the sitosterol infusions (not statistically significant). The cholesterol 7α‐hydroxylase activity was slightly depressed (ca. 30%). In the case of 7α‐hydroxylation of endogenous cholesterol, the depression reached statistical significance (p<0.05). The microsomal content of sitosterol in the sitosterol‐infused rats was about 30% of that of microsomal cholesterol. The effect of sitosterol on 7α‐hydroxylation of cholesterol was investigated by incubations of acetone powder of rat liver microsomes with mixtures of cholesterol and sitosterol. Sitosterol mixed with cholesterol to a composition similar to that found in the above microsomal fraction had a depressing effect on 7α‐hydroxylation of cholesterol. This degree of depression was of the same magnitude as that found in the sitosterol infusion experiments. The possibility is discussed that the hypercholesterolemia obtained in the β‐sitosterol‐infused rats is due to the inhibitory effect of sitosterol on the cholesterol 7α‐hydroxylase.
Phosphatidylinositol 4,5‐bisphosphate phospholipase C activity in particulate preparations from rat brain
Authors: Bergers Mieke , Lendi Sonja , Mier Paul D. 
Published: November 2006

AbstractWe describe the hydrolysis of phosphatidylinositol 4,5‐bisphosphate by a particulate rat brain preparation in the presence of the cationic detergent, cetrimide. The optimum cetrimide concentration was in the range 0.2–0.4 mg/ml; at higher or lower concentrations, the reaction rate diminished abruptly, suggesting that the electrical charge density of the micelle is critical for enzymatic attack. In other respects, such as its partial requirement for Ca++ and its pH optimum of about 7.0, the particulate enzyme seems similar to soluble preparations which have been reported previously. Interestingly, the particulate preparation could be stimulated about fourfold by a soluble brain extract in the presence of 1 mM guanosine triphosphate, confirming that the enzyme is the catalytic subunit in a membrane‐bound signal‐transduction system.
Dietary N−6 and N−3 fatty acids and salt‐induced hypertension in the borderline hypertensive rat
Authors: Mills David E. , Ward Ron P. , Mah Marvin , DeVette Linda 
Published: November 2006

AbstractThis study examined the effects of salt‐loading on blood pressure (BP) development in the borderline hypertensive rat (BHR) and its modification by dietary n−3 and n−6 fatty acids. In experiment 1, 4 groups (n=10/group) of male BHR receiving 1% NaCl as a replacement for tap water were placed on chow enriched with either olive oil (OL), sunflower oil (SUN), evening primrose oil (EPO) or fish oil for 6 weeks. BP, heart rate, body weight, water, Na+ and K+ intake and urinary output were measured weekly. SUN and fish oil reduced the pressor response to salt seen vs the OL group by 50%, and EPO abolished the pressor response, reducing BP below control levels. The BP response was unrelated to either food intake or water and electrolyte intake and excretion. In experiment 2, male BHR received water +/− 18∶3n−6 (0.04 mg/hr in OL via ip pump) or 1% NaCl +/− 18∶3n−6 (n=12/group) for 12 weeks, followed by 2 weeks recovery on tap water. Salt increased BP, and 18∶3n−6 decreased this response, but had no effect on animals receiving tap water. In experiment 3, effects of 3 doses of 18∶3n−6 (0.04, 0.08, and 0.12 mg/hr) on the pressor response to 1% NaCl were examined. All doses reduced the BP response to salt vs controls with no dose‐response. These data suggest that the BHR is genetically salt‐sensitive, and that dietary n−3 and n−6 fatty acids can attenuate the cardiovascular response to salt in this model.
Serum lipoprotein and apoprotein concentrations in 4‐(4‐chlorophenyl)‐2‐hydroxytetronic acid and clofibrate‐treated cholesterol and cholic acid‐fed rats
Authors: Kamanna Vaijinath S. , Newman Howard A. I. , Patel Suman T. , Tehim Ahsok K. , Witiak Donald T. , Feller Dennis R. 
Published: November 2006

AbstractInfluence of clofibrate and an aci‐reductone, 4‐(4‐chlorophenyl)‐2‐hydroxytetronic acid (CHTA) on lipoproteins and apoproteins was studied in cholesterol‐ plus cholic acid‐fed rats. CHTA (0.4 mmol/kg body wt, twice daily) significantly lowered serum total cholesterol and triglyceride concentrations at both 10 and 16 days, whereas clofibrate at the same dose did not alter serum cholesterol levels, but elevated serum triglyceride concentrations at 16 days. The abnormal cholesterol‐rich very low density lipoproteins (VLDL), intermediate density lipoproteins (IDL) and low density lipoproteins (LDL) produced by cholesterol plus cholic acid were significantly reduced in their cholesterol content by treatment with CHTA, a compound having an oxidation reduction potential. Conversely, clofibrate administration increased VLDL‐cholesterol with concomitant decreases in IDL‐ and LDL‐cholesterol concentrations. Administration of CHTA to cholesterol‐ plus cholic acid‐fed rats significantly increased concentrations of VLDL and IDL, but had no effect on HDL protein. Both CHTA and clofibrate administration to cholesterol‐ plus cholic acid‐fed rats significantly lowered IDL protein concentrations.Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) studies of apoproteins revealed that clofibrate treatment significantly reduced apoC‐III and C‐II in VLDL, C‐II in IDL, and apoA‐IV and A‐I in HDL. Rats treated with CHTA significantly raised apoC‐II and C‐III in HDL.Isoelectric focusing (IEF) of VLDL apoproteins showed a significant decrease in apoC‐II, C‐III‐0 and apoC‐III‐3 in clofibrate‐treated animals. Thus, the mechanism for antilipidemic action of the oxidation reduction compound, CHTA, which differs markedly from the prototype drug, clofibrate, is independent from major apoprotein modification.
Cardiac membrane vitamin E and malondialdehyde levels in heart muscle of normotensive and spontaneously‐hypertensive rats
Authors: Janero David R. , Burghardt Barbara 
Published: November 2006

AbstractThe vitamin E (α‐tocopherol) and free and bound malondialdehyde (MDA) in ventricular heart muscle and myocardial membrane from Wistar‐Kyoto (W/K) normotensive and spontaneously hypertensive (SH) rats have been measured directly by high performance liquid chromatography (HPLC). Thiobarbituric acid‐reactive substance (TBA‐RS) in the myocardium and heart‐muscle membrane of the two strains was also quantified by a colorimetric TBA test. It was found that SH‐rat myocardium and myocardial membrane contained more than 3‐fold less α‐tocopherol than did heart muscle and cardiac membrane of the normotensive rat. Coincident with this relative vitamin E deficiency were several‐fold greater amounts of MDA and TBA‐RS in SH‐rat myocardium and myocardial membrane. Most (87%) of the MDA in SH‐rat heart muscle, but only 40% in W/K‐rat heart muscle, was free (i.e., unbound). These results offer direct evidence that SH‐rat myocardium is vitamin E‐deficient and highly peroxidative, relative to cardiac muscle of the normotensive W/K parent strain. The lower vitamin E content of SH‐rat myocardium is particularly striking, because SH‐rat myocardial membrane was found to contain ∼35% more phospholipid than myocardial membrane in the W/K rat. Although the amounts of myocardial TBA‐RS are greater in the SH strain, they do not reflect the actual MDA profiles of the heart muscles or the heart membranes and cannot be used as a quantitative index of cardiac oxidative‐injury status due to non‐MDA TBA‐RS in both strains.
Effect of dietarytrans fatty acids on some membrane‐associated enzymes and receptors in rat heart
Authors: Alam Syed Q. , Ren Yun‐Fang , Alam Bassima S. 
Published: November 2006

AbstractThree groups of male weanling Sprague‐Dawley rats were fed diets containing 20% corn oil, 20% partially hydrogenated soybean oil (PHSBO) or 18% PHSBO +2% corn oil. PHSBO contained about 48% of its total fatty acids astrans‐octadecenoate. Rats were killed after 16–18 weeks of feeding the various diets, hearts were dissected and crude sarcolemma was prepared by differential centrifugation. The activities of ouabain‐sensitive (Na++K+)ATPase were significantly lower in membranes of rats fed 20% PHSBO than the control rats fed 20% corn oil. The feeding of 2% corn oil with 18% PHSBO resulted in partial restoration of the enzyme activity. The maximum number of [3H]ouabain‐binding sites (Bmax) was also lower in cardiac membranes of rats fed 20% PHSBO than those fed 20% corn oil. Similar to (Na++K+)ATPase activity, some restoration of the number of [3H]ouabain‐binding sites was observed when 2% corn oil was fed with 18% PHSBO‐containing diet. There was no difference in the binding affinity of the radioligand for the receptor among the 3 dietary groups. Adenylate cyclase activities (fluoride‐, isoproterenol‐ and forskolinstimulated) were lower in membranes of rats fed 20% PHSBO or 18% PHSBO +2% corn oil than in the control group fed 20% corn oil. Density of the β‐adrenergic receptor was the lowest in cardiac membranes of rats fed 20% PHSBO. The feeding of 2% corn oil with 18% PHSBO resulted in partial restoration of the maximum number of [3H]dihydroalprenolol (DHA)‐binding sites. The affinity of the binding sites was, however, not affected by the type of the dietary fat. The results of this study suggest that dietarytrans fatty acids can affect the activities of (Na++K+)ATPase and adenylate cyclase and the density of digitalis and β‐adrenergic receptors in rat heart.
Mechanisms of linoleic acid uptake by rabbit small intestinal brush border membrane vesicles
Authors: Ling Kit‐Yin , Lee Hsin‐Yi , Hollander Daniel 
Published: November 2006

AbstractWe examined the initial transport of a long‐chain unsaturated fatty acid, linoleic acid, by brush border membrane vesicles isolated from rabbit small intestine. This preparation allowed us to examine the transport of linoleic acid across the brush border membrane without the effect of the unstirred water layer or cytosol binding proteins. Linoleic acid was solubilized in a 2 mM taurocholate solution which did not compromise the functional integrity of the vesicles. Linoleic acid uptake in the range of 1 to 100 μM followed passive diffusion kinetics. Time course study showed that linoleic acid uptake reached maximal levels during the initial 15 seconds. Although the amount of linoleic acid accumulated in the vesicles diminished over the next 30 minutes, the molar quantity was still twentyfold higher than that of D‐glucose (6.5 vs 0.33 nmol/mg protein). Uptake of D‐glucose by the vesicles demonstrated typical osmotic responsiveness. We found no osmotic effect on linoleic acid uptake. Hypotonic lysis of membrane vesicles loaded with linoleic acid released 40% of the fatty acid. We concluded that a major portion of the accumulated fatty acid was bound to or incorporated into the membrane itself while ca. 40% did traverse the membrane and accumulated in the intravesicular space as nonmicellar aggregates. The known inhibitors of anion transport, diisothiocyanatostilbene and isothiocyanatostilbene did not change the transport of linoleic acid. We conclude that, in the absence of an unstirred layer or cytosol proteins, linoleic acid transport at up to 100 μM concentration is passive with rapid accumulation both by the cell membrane and the lumen of vesicles.
Incorporation oftrans‐8‐ andcis‐8‐octadecenoic acid isomers in human plasma and lipoprotein lipids
Authors: Emken E. A. , Adlof R. O. , Rohwedder W. K. , Gulley R. M. 
Published: November 2006

AbstractMixtures of deuterium‐labeledtrans‐8‐,cis‐8‐ andcis‐9‐octadecenoic acids (8t–18∶1, 8c–18∶1, 9c–18∶1) were fed as triglycerides (TG) to two adult male subjects. Blood samples were collected sequentially over a 48‐hour period. Plasma and lipoprotein lipids were separated by thin layer chromatography and analyzed by gas chromatography‐mass spectroscopy. Results indicate (i) absorption of the 8t‐ and 8c–18∶1 isomers were similar to 9c–18∶1; (ii) the 8t–18∶1 isomer was cleared approximately 30% faster than 9c–18∶1 from plasma TG; (iii) cholesterol ester samples contained 8.4 times less 8t–18∶1 than 9c–18∶1; (iv) incorporation at the 1‐acyl phosphatidylcholine (PC) position was higher for 8t–18∶1 and 8c–18∶1 (2.2 and 1.7 times) than for 9c–18∶1; and (v) discrimination at the 2‐acyl PC position was 4.6‐fold against 8t–18∶1 and 1.3‐fold against 8c–18∶1 compared with 9c–18∶1. Discrimination against uptake of the Δ‐8 isomers in both neutral and phospholipid classes suggests that both 8t‐ and 8c–18∶1 may be preferentially oxidized relative to 9c–18∶1. Except for triglycerides, data for each of the lipid classes from total plasma and individual lipoprotein samples were similar. These data indicate that differences for incorporation and turnover of the 8t‐ and 8c–18∶1 isomers relative to 9c–18∶1 are not substantially influenced by the lipoprotein classes. The maximum isotopic enrichment detected in the chylomicron triglycerides fractions was 60%, which indicates that a substantial amount of endogenous triglycerides was mobilized during absorption of the deuterated fats.