bluuebunny/crossref_metadata_2025_split huggingface dataset:
Changes in lipids in liver and serum of rats fed a histidine‐excess diet or cholesterol‐supplemented diets
Authors: Ohmura Eri , Aoyama Yoritaka , Yoshida Akira 
Published: November 2006

AbstractThe influence of dietary excess (5%) L‐histidine on serum and liver lipids was examined in rats. Feeding a histidine‐excess diet for 3, 6, 14 or 30 days caused growth retardation, hepatomegaly and decreased liver lipids throughout the period of the experiment. Hypercholesterolemia was observed after feeding a histidine‐excess diet for 6 days; then serum cholesterol continuously increased for 30 days. Serum triglyceride on day 30 in rats fed the histidine‐excess diet showed a significant decrease compared to rats fed the basal diet. Serum phospholipids of rats fed the histidine‐excess diet for 7 or 14 days showed a significant increase compared to rats fed the basal diet. When rats were fed a basal, histidine‐excess or cholesterol‐supplemented diet (0.5% and 1.0% cholesterol) for 6 days, the distribution of serum high density (HDL), low density (LDL) and very low density lipoprotein cholesterol in rats fed the histidine‐excess diet was similar to that of rats fed the basal diet, whereas LDL‐cholesterol increased and HDL‐cholesterol decreased in rats fed the cholesterol‐supplemented diet.
Regulation of cholesterol synthesis in isolated epithelial cells of human small intestine
Authors: Sviridov D. D. , Safonova I. G. , Talalaev A. G. , Repin V. S. , Smirnov V. N. 
Published: November 2006

AbstractWe have investigated the regulation of cholesterol synthesis in isolated human small intestine epithelial cells (enterocytes). It was established that the amount of cholesterol synthesized increased linearly with the incubation time and the number of cells in the incubation mixture; the synthesis was suppressed by 7‐ketocholesterol. Cholic, dehydrocholic, chenodeoxycholic, glycocholic, taurocholic, taurochenodeoxycholic and taurodeoxycholic acids inhibited cholesterol synthesis in enterocytes to different degrees in a dose‐dependent manner. Lithocholic acid enhanced the rate of cholesterol synthesis. Deoxycholic acid, methyl ester of cholic acid and cholesterol did not affect the process. No bile acids tested, with the exception of taurodeoxycholic acid, affected fatty acid synthesis in enterocytes. Most bile acids also decreased cholesterol synthesis in cultured human skin fibroblasts. The results obtained make it possible to postulate that cholesterol synthesis in human enterocytes may be subject to a complex regulation by bile acids.
Species differences in lipid peroxide levels in lung tissue and investigation of their determining factors
Authors: Arakawa Kenji , Sagai Masaru 
Published: November 2006

AbstractMarked species differences in thiobarbituric acid reactant value (TBA value) in normal lung tissue of five species of animals were found. The order of the values was mouse > hamster > rat > guinea pig > rabbit, and the value for mice was 3.6 times higher than that for rabbit. The vitamin E (VE) and nonprotein sulfhydryls (NPSH) contents in lungs varied widely among the five animal species. Species differences were also observed on polyunsaturated fatty acid composition in lung phospholipids. The peroxidizability index (PI), which shows the relative rate of peroxidation reaction, was calculated from the composition ratio and the reactivity of each polyunsaturated fatty acid, and the PI was found to be significantly correlated to the TBA value in lungs (r=0.853, p<0.001). The PI value was normalized by the contents of VE and/or NPSH. Finally, the log‐value of PI, normalized by the log values of the reciprocals of VE and NPSH, log(PI/VE·NPSH), showed the highest correlation coefficient (r=0.907, p<0.001). Normalization by the activities of antioxidative protective enzymes in lungs did not show any significant correlation against TBA value. These results suggest that TBA value as an index of lipid peroxides in the lungs of animals may be regulated mainly by the contents of VE and NPSH, the composition ratio and the reactivity of each polyunsaturated fatty acid in lung phospholipid fraction.
Limitations of the method using peroxidase activity of hemoglobin for detecting lipid hydroperoxides
Authors: Shibata Selma Setsu , Terao Junji , Matsushita Setsuro 
Published: November 2006

AbstractThe method using peroxidase activity of hemoglobin (Hb) for the determination of lipid peroxides was examined by using pure methyl linoleate hydroperoxides, trilinoleoylglycerol hydroperoxides and egg yolk phosphatidylcholine hydroperoxides as substrates and tetramethyl benzidine as electron donor for the peroxidase reaction of Hb. The reactivities of these substrates were quite varied. Furthermore, some electron donors were tested for peroxidase activity of Hb, but none showed a complete reduction of methyl linoleate hydroperoxides. From these results, it seems the Hb method needs to be carefully applied to biological materials that contain mixtures of different types of lipid classes.
Effects of dietary fiber in Vervet monkeys fed “Western” diets
Authors: Kritchevsky David , Davidson Larry M. , Scott Daniel A. , Van der Watt J. J. , Mendelsohn Dennis 
Published: November 2006

AbstractMale Vervet monkeys (7/treatment) were fed a “Western” diet containing 46.2% calories as fat, 39.8% as carbohydrate and 14.0% as protein. The diet was augmented with 10% cellulose or 10% pectin. A third (control) group of seven monkeys was fed a commercial ration augmented with fruit and bread. After 34 weeks, serum cholesterol levels were elevated significantly in the two test groups compared with the controls but there was no difference between the two fiber‐fed groups. Serum triglycerides were unaffected. Liver cholesterol levels were the same in all three groups but liver triglyceride levels were lower in the monkeys fed cellulose. Biliary lipids were similar in all three groups as were the calculated lithogenic indices. The average aortic sudanophilia (percent of total area) in the three groups was cellulose, 10.6±2.5; pectin, 8.1±2.5; and control, 1.1±0.4. One animal in each of the groups fed “Western” diet exhibited an atherosclerotic plaque. The results indicate that there is no difference between pectin and cellulose with regard to their effects on either lipidemia or aortic sudanophilia in Vervet monkeys fed a Western‐type diet.
Hypocholesterolemic action of chitosans with different viscosity in rats
Authors: Sugano Michihiro , Watanabe Shuji , Kishi Akihiro , Izume Masato , Ohtakara Akira 
Published: November 2006

AbstractThe relationship between hypocholesterolemic efficacy and average molecular weight of chitosan was studied in rats fed a cholesterol‐enriched (0.5%) diet. Several chitosan preparations with a comparable degree of deacetylation but differing widely in average molecular weight, as demonstrated by viscosity, almost completely prevented the rise of serum cholesterol at the 5% dietary level. At the 2% level, chitosans with viscosities at both extremes exerted a comparable cholesterol‐lowering action. The glucosamine oligomer composed mainly of three to five aminosugar residues was not effective. The results indicate that the hypocholesterolemic action of chitosans is independent of their molecular weight within the tested viscosity range.
Testing a short‐term feeding trial to assess compositional and histopathological changes in hearts of rats fed vegetable oils
Authors: Kramer J. K. G. , Farnworth E. R. , Thompson B. K. , Corner A. H. 
Published: November 2006

AbstractMale, female and castrated rats, three wk of age, were fed a low‐fat diet for 14 wk followed by high‐fat diets (20% by weight) for one wk containing graded levels of erucic acid from 1 to 50%, to evaluate the effect of short‐term feeding and interaction of male sex hormones on formation of heart lesions. Some rats within each group were returned to the low‐fat diet for one wk after the test period. For comparison, one group of three‐wk‐old male rats was fed the high fat 50% erucic acid diet for 15 wk. Erucic acid depressed growth rate and food consumption and increased cardiac lipidosis and triglycerides proportional to the erucic acid content of the diet. There were no sex differences, and the effects disappeared once rats were returned to the low‐fat diet for one week. There was a significance (P<0.05) in the incidence of myocardial necrosis among male rats fed increased levels of erucic acid for one week, but the response was not linear to the increase in dietary erucic acid. Furthermore, the response was much less than in males fed the 50% erucic acid diet continually for 15 weeks. These results suggest that the short‐term model is not a suitable substitute for the long‐term feeding trial to test the cardiopathogenicity of a vegetable oil. The significantly lower incidence in myocardial lesions in female and castrated male rats compared with male rats suggests involvement of sex hormones. However, the process appears to be long term, since changes in cardiac lipids and their fatty acid pattern between sexes became evident after one wk on diet but was significant only after long‐term feeding.
(3H)Forskolin‐ and (3H)dihydroalprenolol‐binding sites and adenylate cyclase activity in heart of rats fed diets containing different oils
Authors: Alam Syed Q. , Ren Yun‐Fang , Alam Bassima S. 
Published: November 2006

AbstractThe characteristics of the cardiac adenylate cyclase system were studied in rats fed diets containing fish oil (menhaden oil) and other oils. Adenylate cyclase activity generally was higher in cardiac homogenates and membranes of rats fed diet containing 10% menhaden oil than in the other oils. The increase in enzyme activity, especially in forskolin‐stimulated activity, was associated with an increase in the concentration of the [3H]forskolin‐binding sites in cardiac membranes of rats fed menhaden oil. The β‐adrenergic receptor concentration was not significantly altered although the affinity for [3H]dihydroalprenolol‐binding was lower in membranes of rats fed menhaden oil than those fed the other oils. ω‐3 fatty acids from menhaden oil were incorporated into the cardiac membrane phospholipids. The results suggest that the observed increase in myocardial adenylate cyclase activity of rats fed menhaden oil may be due to an increase in the number of the catalytic subunits of the enzyme or due to a greater availability of the forskolin‐binding sites.
Structural modifications of rat serum high density lipoprotein by pancreatic phospholipase A2
Authors: Swaney John B. , Orishimo Margaret W. 
Published: November 2006

AbstractAn important and unusual aspect of the high density lipoprotein (HDL) in the rat is its tendency to undergo marked alterations in structure in response to physiological perturbations. In this study, the role of the surface lipids for maintenance of HDL integrity were investigated. Hydrolysis by pancreatic phospholipase A2 of the phospholipids of rat HDL in the presence of the d>1.21 g/ml fraction of rat serum results in an increase in the particle diameter and an uptake of apo‐E and apo A‐IV from the lipoprotein‐free fraction; augmentation of the albumin concentration in the incubation mixture intensified the observed changes, probably due to enhancement of the compositional changes brought about by phospholipase treatment. Phospholipase A2 treatment of the d<1.21 g/ml fraction of rat serum produces only minor changes in the properties of the isolated HDL. These data suggest that changes in apoprotein content reflect an uptake of A‐IV and E by the rat HDL, rather than a net loss of apo A‐I. Likewise, titration of the action of pancreatic phospholipase A2 on HDL apoprotein composition showed that initially a modest increase in apo A‐IV content occurred, but with more extensive phospholipolysis there was a considerably greater increase in the apo‐E content of the particle. The data suggest that hydrolysis of phospholipids such as occurs physiologically through the action of lecithin: cholesterol acyl transferase and hepatic lipase may alter the HDL structure independently from changes effected in the neutral lipid core.
Normalization of high density lipoprotein in fish eye disease plasma by purified normal human lecithin: Cholesterol acyltransferase
Authors: Holmquist Lelf , Carlson Lars A. 
Published: November 2006

AbstractPlasma from a patient with fish eye disease has been enriched with autologous high density lipoproteins (HDL) and supplemented with highly purified normal human plasma lecithin:cholesterol acyltransferase (LCAT). Incubation of such plasma at 37 C in vitro resulted in normalization of its low HDL cholesteryl ester percentage, from 23% to 79%, associated with a two‐fold increase in both the cholesteryl ester and triglyceride contents of the HDL fraction, as compared to incubation experiments with absent or heat‐inactivated purified normal LCAT.The normalization of the HDL cholesteryl ester percentage induced by incubation with purified normal LCAT also was accompanied by an increase in the size of the original fish eye disease HDL particles, which had a mean mass of 115 kd, to HDL particle populations with mean particle masses ranging from 130–220 kd, depending on the concentration of purified LCAT in the incubate. Both HDL cholesterol esterification and particle enlargement were abolished completely by the LCAT inhibitor DTNB and by heat inactivation of the purified normal LCAT. The results give further evidence that fish eye disease is an α‐LCAT deficiency.
Cholesterol synthesis in the pathogenesis of lithocholic acid‐induced cholestasis
Authors: Yousef I. M. , Tuchweber B. , Morazain R. , Gauvin M. , Roy C. C. , Weber A. M. 
Published: November 2006

AbstractLithocholic acid (LCA)‐induced intrahepatic cholestasis is associated with increased de novo synthesis of hepatic cholesterol and augmented cholesterol content of the liver cell plasma membrane fraction enriched in bile canalicular complexes (BCM). To determine whether inhibition of cholesterol synthesis could prevent LCA‐induced cholestasis, adult male Wistar rats were treated daily with the hypocholesterolemic agents, clofibrate (250 mg/kg) or mevinolin (25 mg/kg), for one, two or four days. After bile duct cannulation and bile collection for one hr, the animals were injected intravenously with 120 μmoles/kg of LCA or its carrier (albumin). Cholesterol synthesis was measured in liver homogenates, and its contribution to the BCM was estimated. LCA reduced bile flow by 51%, 35% and 25% after clofibrate pretreatment for one, two and four days, respectively, and by 51%, 30% and 42% in mevinolin‐pretreated animals after one, two and four days. In control animals, cholesterol synthesis and the contribution of newly synthesized cholesterol in the BCM were increased after LCA injection. However, despite that cholesterol synthesis and the contribution of newly synthesized cholesterol in the BCM were reduced in drug‐pretreated rats, LCA injection caused a relative increase in these parameters of a magnitude similar to that observed in controls. Thus, the ability of LCA injection to augment de novo cholesterol synthesis and its transport to the BCM may be an important pathogenetic step in the development of cholestasis.
Lipogenic enzyme activities in primary cultures of adult mouse hepatocytes
Authors: Hillyard Lewis A. , Lin C. Y. , Abraham S. 
Published: November 2006

AbstractThe effects of various unsaturated fatty acids such as oleic (18∶1n−9), linoleic (18∶2n−6) and arachidonic (20∶4n−6) on the activities of fatty acid synthetase (FAS), malic enzyme (ME), glucose‐6‐phosphate dehydrogenase (G6PDH) and 6‐phosphogluconate dehydrogenase (6PGDH) all were determined in primary cultures of mouse hepatocytes. Activities of FAS and ME were found to decrease with time in culture regardless of whether hepatocyte donors were fed diets containing polyunsaturated fatty acid‐free hydrogenated cottonseed oil (HCTO) or corn oil (CO). On the other hand, while G6PDH activity also declined in cultured hepatocytes obtained from HCTO‐fed mice, the activity of this enzyme increased in cells cultured from CO‐fed mice. 6PGDH activity was found to increase in hepatocytes obtained from both diet groups. Neither 18∶2 nor 20∶4 when added to media could alter FAS or ME activities compared with those observed with either 18∶1‐containing or fatty acid‐free media. Since lactic dehydrogenase activity and the rate of incorporation of [3H] leucine into FAS protein were unaltered with time in hepatocyte cultures, the decreased activities of FAS and ME cannot be attributed to a loss in cell viability during culture but rather appear to be specific for those enzymes which respond to diet hormones in vivo. Examination of the fatty acid contents of the cells after the culture period showed that the values for the ratios of 16∶0/16∶1 and of 18∶0/18∶1 were elevated when either 18∶2 or 20∶4 was added to the medium even though there was no evidence for elongation of the added 18∶2 or for 20∶4 being converted to 22∶4. This result suggest that Δ9‐desaturase activity was inhibited by these polyunsaturated fatty acids and that conversion of 18∶2 to 20∶4 was not required for such action.The rate of synthesis determined by the relative rate of incorporation of [3H]leucine into FAS was two to five times higher in hepatocytes prepared from mice fed the HCTO diet than in hepatocytes from mice fed the CO diet. We have concluded that the mechanisms for long‐term regulation may not be contained entirely within the liver.
Quantitation of 1,2‐diacylglycerol in rat heart by latroscan TLC/FID
Authors: Okumura Kenji , Hashimoto Hidekazu , Ito Takayuki , Ogawa Kouichi , Satake Tatsuo 
Published: November 2006

Abstract1,2‐Diacylglycerol, which has been recognized as one of the intracellular second messengers, was measured quantitatively in the lipid extract from rat hearts using the thin layer chromatography and flame ionization detection (TLC/FID) method. Cholesterol acetate was added to the tissue as an internal standard, and the crude lipids from the tissue were purified with silicic acid column to eliminate phospholipids. Development of Chromarods was carried out using two solvent systems and a three‐step development technique. The relationship of the peak area ratio detected by flame ionization detector to weight ratio was linear compared with cholesteryl acetate. The 1,2‐diacylglycerol content in the rat heart in the unstimulated condition was 72.5±15.3 ng/mg wet wt (mean±SD).
Molecular species of glycerolipids of ehrlich ascites cells and of their fat granules
Authors: Myher J. J. , Kuksis A. , Pind S. , Kay E. R. M. 
Published: November 2006

AbstractEhrlich ascites cells were grown in mice and were isolated by centrifugation of the ascites fluid. The cells were lysed with distilled water, and the floating fat particles were collected by centrifugation. The particles contained about 90% neutral and 10% polar lipid. The neutral lipid was made up of about 50% triacylglycerol, 30% alkyldiacylglycerol, 3% cholesteryl esters, 3% free cholesterol and 4% free diacylglycerols. The phospholipid fraction was comprised of about 50% phosphatidylcholine, 35% phosphatidylethanolamine, 10% sphingomyelin and small amounts (less than 5% total) of serine and/or inositol phosphatides. The triacylglycerol and alkyldiacylglycerol fractions possessed total carbon number and fatty acid compositions closely similar to these reported in the literature for whole ascites cells and for a cell membrane preparation. Likewise, the fatty acid composition of phospholipids from the granules in general was similar to that reported for Ehrlich ascites cells. On the basis of the polar and neutral lipid ratio, the lipid granules of the ascites cells were calculated to possess lipid core diameters of 30–50 nm, which were 40–70 times smaller than those (up to 2μ) measured for the lipid granules of the intact cells by electron microscopy. The characterization of the lipid composition of the Ehrlich ascites lipid granules was completed by determing the molecular species composition of the diacyl, alkylacyl and alkenylacyl phosphatidylethanolamines and of the diacyl and alkylacyl phosphatidylcholines of the ascites cells. It is concluded that the alkyldiacylglycerols of the Ehrlich ascites cells occur largely in the cytoplasmic lipid granules, which appear to consist of many particles of the size and structure of very low density lipoproteins enclosed in membranous sacs.
Effect of dietary vitamin E and selenium on susceptibility of brain regions to lipid peroxidation
Authors: Meydani Mohsen , Macauley John B. , Blumberg Jeffrey B. 
Published: November 2006

AbstractThe effect of dietary vitamin E and/or selenium (Se) supplementation (200 IU and/or 0.2 ppm, respectively) or deficiency for two months on lipid peroxidation in cerebrum, cerebellum, mid‐brain, and brain stem of one‐month‐old male F344 rats was investigated. Dietary treatment had a minimal effect on weight gain of rats for the period tested. Plasma α‐tocopherol (α‐T) concentration and glutathione peroxidase (GSH‐Px) activity were reflective of dietary treatments. Supplementation of diets with vitamin E and/or Se increased plasma α‐T and/or GSH‐Px activity, while diets devoid of these nutrients reduced them significantly. Increased GSH‐Px activity in Sesupplemented rats was further enhanced by vitamin E supplementation. Differential concentrations of α‐T among brain regions were affected by dietary vitamin E but not by Se. In vitro lipid peroxidation of brain homogenates was inhibited by dietary vitamin E supplementation and increased by deficiency. Addition of 0.25 mM ascorbic acid or 0.1 mM of Fe2+ to brain homogenates markedly increased in vitro lipid peroxidation. Ascorbic acid‐induced lipid peroxidation was inversely correlated with dietary vitamin E and Se in cerebrum. In vitro Fe2+‐addition induced the greatest stimulation of lipid peroxidation, with cerebellum and brain stem of vitamin E‐deficient rats showing the highest response to Fe2+ challenge. These findings indicate that concentrations of α‐T among the brain regions are different and can be altered by dietary vitamin E treatments, cerebellum and brain stem are more susceptible to in vitro challenge by peroxidative agents than other regions, and the degree of lipid peroxidation of brain regions is partially affected by dietary vitamin E but not by Se in the levels tested.
Isolation and characterization of proteolipids from rat liver (LSP) and kidney (KSP)
Authors: Jüngst Dieter , Blumenstingl Johann , Caselmann Wolfgang H. 
Published: November 2006

AbstractIn this study, the biochemical characteristics of proteolipids of rat liver and kidney homogenates were compared. In all preparations, the proteo‐lipids were eluted at the void volume of the Biogel A‐15 m column after gel chromatography, and a molecular weight over 15×106 was estimated. Electron microscopy of the concentrated void volume fractions showed globular particles with diameters of 30–100 nm for liver (LSP) and 30–60 nm for kidney (KSP) preparations that might be formed from plasma membrane fragments. After ultracentrifugation in a CsCl gradient, rat LSP and KSP floated in a small density range from 1.16–1.17 g/ml. There was no significant difference between the relative percentages of phospholipids, triglycerides and cholesterol of both proteo‐lipids. However, the relative mean amount of total protein in rat KSP (60.4% vs 50.4%) was significantly higher and the content of free fatty acids (4.3% vs 12.6%) significantly lower compared to rat LSP. SDS‐PAGE revealed at least 12 protein subunits ranging from 15,000–130,000 in both preparations, but one protein of about Mr 49,000 might represent a liver specific component. The isolated proteo‐lipids from rat liver and kidney homogenates showed similar biochemical characteristics as those from human sources, which could explain the known cross‐reactivity of antibodies against these preparations.The putative function of these proteo‐lipids is not known, although there is some evidence from human studies that they carry receptor proteins.