Hoạt động của hệ thống enzym oxy hóa chức năng hỗn hợp gan ở chuột được cho ăn chất béotrans Dịch bởi AI Lipids - Tập 20 Số 5 - Trang 325-327 - 1985
Kikuko Nishiyama, Takashi Ishii, Michihiro Sugano
Tóm tắtChuột được cho ăn chế độ ăn chứa dầu camellia hoặc dầu ngô bán hydro hóa, như một nguồn củacis hoặctrans octadecenoate, tương ứng, trong sự hiện diện của axit linoleic đầy đủ. Sau 35 ngày cho ăn chế độ ăn, hoạt động của một số enzym chuyển hóa thuốc trong gan cũng như nồng độ cytochrome P‐450 microsome trong gan đã được xác định. Sự khác biệt về hình học trong chất béo chế độ ăn không ảnh hưởng đến lượng protein microsome cũng như nồng độ cytochrome P‐450. Hơn nữa, hoạt động của NADPH cytochrome C reductase, aminopyrine N‐demethylase và biphenyl hydroxylase cũng tương tự giữa hai nhóm chuột. Hoạt động hydroxylase aniline tăng nhẹ ở chuột được cho ăn chất béotrans. Kết luận rằng sự khác biệt về hình học của axit béo trong chế độ ăn không có nhiều ảnh hưởng đến việc điều chỉnh hệ thống oxy hóa chức năng hỗn hợp trong gan.
Conjugation of polyunsaturated acidsLipids - - 1970
T. L. Mounts, H. J. Dutton, D. Glover
The isomerization reaction of methyl linoleate and methyl linolenate with potassiumt-butoxide has been investigated. The compositions of the reaction products formed at three temperatures have been determined and the relationships between these analyses and observed differences in absorptivities by UV spectrometry are discussed. Conclusions concerning the reaction mechanisms are based on compositional analysis and results of experiments using radioactive or stable isotope labeled reagent. Double bonds in molecules which are not conjugated during the reaction retain the originalcis configuration. The double bond in the Δ12 position is the most susceptible to positional isomerization to form the conjugated system. With the diene, this selectivity is small, while with the triene, the shifting of the Δ12 bond is the preponderant initial reaction. Isotopic experiments yielded direct evidence for the postulated carbanion mechanism of reaction. An activated methylene group is generally required for the formation of the carbanion. While the UV spectra of the reaction products formed from methyl linolenate at 140 C showed no peak in the diene region, 34% conjugated diene-triene was present. The intact conjugated systems can migrate when the reaction is sufficiently energentic to produce conjugated trienes with double bonds other than the 10, 12, 14 system. The conjugation of triene is a stepwise reaction through the conjugated dienetriene.
Clinical trial results support a preference for using CLA preparations enriched with two isomers rather than four isomers in human studiesLipids - Tập 37 - Trang 1019-1025 - 2002
Jean-Michel Gaullier, Grethe Berven, Henrietta Blankson, Ola Gudmundsen
CLA mixtures are now commercially available. They differ from each other with respect to their content of CLA isomers and their degree of purification. As a group of natural FA, CLA have been widely assumed to be safe. However, the suspected presence of both impurities and particular isomers might induce undesirable side effects. Despite this potential health risk, only a few CLA preparations have been tested under rigorous conditions for clinical efficacy and safety. Based on the limited results available, it is possible to suggest that preparations enriched in c9,t11 and t10,c12 isomers are preferable for human consumption compared to preparations containing four isomers, in terms both of safety and efficacy.
Effects of lovastatin on hepatic fatty acid metabolismLipids - Tập 28 Số 12 - Trang 1087-1093 - 1993
Manuel Guzmán, José Emilio Cortés, José María Albertos Castro
AbstractThein vitro andin vivo effects of lovastatin on fatty acid metabolism were studied in isolated rat hepatocytes. When addedin vitro to cell incubations, lovastatin stimulatedde novo fatty acid synthesis and acetyl‐CoA carboxylase activity, whereas fatty acid synthase, activity was unaffected. Lovastatin depressed palmitate, but not octanoate, oxidation. This may be attributed to the lovastatin‐induced increase, in intracellular malonyl‐CoA levels, as no concomitant changes of carnitine palmitoyltransferase I (CPT‐I) specific activity was detected. Lovastatin had no effect on the synthesis and secretion of triacylglycerols and phospholipids in the form of very low density lipoproteins (VLDL). When rats were fed a diet supplemented with 0.1% (w/w) lovastatin for one week, both acetyl‐CoA carboxylase activity andde novo fatty acid synthesis were reduced compared to pair‐fed controls, whereas fatty acid synthase activity was unaffected. Palmitate oxidation was enhanced in the lovastatin‐fed group. There was an increase in CPT‐I activity but no change in intracellular concentration of malonyl‐CoA. Lovastatin feeding and no significant effect either on the esterification of exogenous palmitic acid into both cellular and VLDL triacylglycerols and phospholipids or on hepatic lipid accumulation. Thein vitro andin vivo effects of lovastatin were not significantly different between periportal and perivenous hepatocytes. The results indicate that: (i) the administration of lovastatin increased the fatty acid‐oxidative capacity of the liver at the expense of its lipogenic capacity, (ii) the rate ofde novo cholesterol synthesis did not seem to be a limiting factor in the synthesis and secretion of VLDL and (iii) lovastatin produced opposite effects on hepatic fatty acid metabolismin vitro andin vivo.
Disseminated Neoplasia in the Soft-Shell Clam Mya arenaria: Membrane Lipid Composition and Functional Parameters of Circulating CellsLipids - Tập 49 - Trang 807-818 - 2014
Fabienne Le Grand, Philippe Soudant, Ahmed Siah, Réjean Tremblay, Yanic Marty, Edouard Kraffe
In a previous study we compared lipid composition and functional parameters of circulating cells from Cerastoderma edule affected or not by disseminated neoplasia (neoplastic cells vs hemocytes) (Le Grand et al. Chem Phys Lipids 167:9–20 2013). Neoplastic cells presented morpho-functional modifications concomitant to striking membrane lipid alterations: the proportion of particular plasmalogen molecular species was drastically decreased. We wanted to test whether this pattern was representative of bivalve neoplastic cells. For the purpose, a similar study was conducted on another bivalve species affected by disseminated neoplasia, the soft-shell clam (Mya arenaria). Although total reactive oxygen species production was unaffected, M. arenaria neoplastic cells presented some functional alterations: phagocytosis activity was reduced by 33 %. However, lipid compositions were not drastically altered. Particularly, sterol and plasmalogen levels did not differ between both cell types (about 43 % of membrane lipids and 35 % of phospholipids, respectively in hemocytes and neoplastic cells). This could be related to the fact that disseminated neoplasia was not related to hemolymph cell proliferation in M. arenaria (0.9 ± 0.2 106cell mL−1, considering both healthy and neoplastic clams, n = 6). Nevertheless this study highlighted minor but specific alterations of membrane lipid composition in M. arenaria neoplastic cells. The only phospholipid subclass in which the fatty acid profile strongly differed between both cell types was serine plasmalogen (PlsSer), with neoplastic cells presenting lower specific enrichment of 20:1n-11 in PlsSer. Such specific alteration of membrane lipid composition strengthened the assumption of an implication of key plasmalogen molecular species in this leukemia-like disease in bivalves.
Effects of dietary saturated andtrans fatty acids on cholesteryl ester synthesis and hydrolysis in the testes of ratsLipids - Tập 11 - Trang 357-363 - 1976
Takehiko Takatori, Frederick Phillips, Orville S. Privett
Studies were made of the enzymic synthesis and hydrolysis of cholesteryl esters in rat testes. Weanling rats were fed for 14 weeks diets containing 5% by wt of hydrogenated coconut oil (HCO), a concentrate of ethyl elaidate and linolelaidate (TRANS), devoid of essential fatty acids (EFA), or safflower oil (SAFF). Cholesterol esterifying activity was localized in the soluble fraction, and cholesteryl ester hydrolase activity was distributed in both particulate and soluble fractions obtained from tissue homogenates. The optimum pH was 6.0 for esterification and 6.9–7.0 for hydrolysis. Neither esterifying nor hydrolytic activity was affected by freezing and thawing, but both reactions were inhibited by heat or sonication. The animals of both the HCO and TRANS groups had developed an EFA deficiency before they were sacrificed. The EFA deficiency produced upon feeding the HCO diet had no apparent effect on the synthesis and hydrolysis of cholesteryl esters in rat testes. The TRANS diet influenced the development of the testes as judged by their size, and cholesterol esterifying and cholesteryl ester hydrolyzing activities were suppressed in the testes of the animals of this group. A major difference in the effects of the HCO and TRANS diets on the lipids of the testes was the relatively minor amount of eicosatrienoic acid (20∶3) and the elevated level of docosapentaenoic acid (22∶5) in the cholesteryl esters of the testicular lipids of the TRANS group.
Regulation of very low density lipoprotein apo B metabolism by dietary fat saturation and chain length in the guinea pigLipids - Tập 33 - Trang 23-31 - 1998
Ghada Abdel-Fattah, Maria Luz Fernandez, Donald J. McNamara
Studies investigated the effects of dietary fatty acid composition and saturation on the regulation of very low density lipoprotein (VLDL) apo B flux, clearance, and conversion to low density lipoprotein (LDL) in guinea pigs fed semipurified diets containing 15% (w/w) corn oil (CO), lard (LA), or palm kernel oil (PK). Plasma cholesterol levels were highest with dietary PK (3.1±1.0 mmol/L) followed by LA (2.4±0.4 mmol/L) and CO (1.6±0.4 mmol/L) intake. VLDL particles were larger (P<0.05) in the LA (78±7 nm) and PK (69±10 nm) groups compared to animals fed CO (49±5 nm). VLDL-apo B fractional catabolic rates (FCR) were highest in guinea pigs fed the LA diet (P<0.05) and VLDL apo B flux, estimated from VLDL 125I-apo B turnover kinetics, were higher in LA compared to PK or CO fed guinea pigs. In the case of PK consumption, the kinetic estimates of VLDL apo B flux significantly underestimated rates compared to direct VLDL apo B secretion measurements and LDL turnover analyses. These data demonstrate that differences in the composition and amount of saturated fatty acids have differential effects on VLDL apo B flux, catabolism, and conversion to LDL which, together with changes in LDL receptor-mediated catabolism, determine plasma LDL cholesterol levels in guinea pigs. The data also indicate that kinetic analysis of VLDL metabolism in PK fed animals is inaccurate possibly due to the presence of a small, nonequilibrating pool of newly synthesized VLDL which is rapidly converted to LDL.
Confirmation by gas chromatography/mass spectrometry of two unusualrans‐3‐monoethylenic fatty acids from the nova scotian seaweedsPalmaria palmata andChondrus crispusLipids - Tập 29 Số 6 - Trang 441-444 - 1994
M. Lamberto, R. G. Ackman
AbstractThe structures of two unusual fatty acids, the knownrans‐3‐hexadecenoic acid and a noveltrans‐3‐tetradecenoic acid, both isolated from the Nova Scotian sea‐weedsPalmaria palmata andChondrus crispus, were positively identified. After the extraction of the total fatty acids by saponification, followed by methylation, the monoenoictrans fractions were isolated by thin‐layer chromatography on silica gel impregnated with silver nitrate. The monoenoictrans fractions were derivatized with 2‐amino‐2‐methyl‐propanol prior to analysis by gas chromatography/mass spectrometry. The mass spectra showed prominent [M+1]+ ions but lacked the 12 amu interval useful for identifying the double bond position. Hence, alternative diagnostic peaks were used to confirm the position of the double bond in these two fatty acids. As thetrans‐3‐hexadecenoic acid is found in the photosynthetic tissue of all plants, it may also be present in ruminant fats and, presumably, in human adipose tissue.
Inhibition of Insulin and T3-Induced Fatty Acid Synthase by HexanoateLipids - Tập 45 - Trang 997-1009 - 2010
Murielle M. Akpa, Floriane Point, Sabine Sawadogo, Anne Radenne, Catherine Mounier
Fatty acid synthase (FAS) is responsible for the de novo synthesis of palmitate and stearate. This enzyme is activated by insulin and T3, and inhibited by fatty acids. In this study, we show that insulin and T3 have an inducing effect on FAS enzymatic activity, which is synergetic when both hormones are present. Octanoate and hexanoate specifically inhibit this hormonal effect. A similar inhibitory effect is observed at the level of protein expression. Transient transfections in HepG2 cells revealed that hexanoate inhibits, at least in part, FAS at a transcriptional level targeting the T3 response element (TRE) on the FAS promoter. The effect of C6 on FAS expression cannot be attributed to a modification of insulin receptor activation or to a decrease in T3 entry in the cells. Using bromo-hexanoate, we determined that hexanoate needs to undergo a transformation in order to have an effect. When incubating cells with triglyceride–hexanoate or carnitine–hexanoate, no effect on the enzymatic activity induced by insulin and T3 is observed. A similar result was obtained when cells were incubated with betulinic acid, an inhibitor of the diacylglycerol acyltransferase. However, the incubation of cells with Triacsin C, a general inhibitor of acyl-CoA synthetases, completely reversed the inhibitory effect of hexanoate. Our results suggest that in hepatic cells, hexanoate needs to be activated into a CoA derivative in order to inhibit the insulin and T3-induced FAS expression. This effect is partially transcriptional, targeting the TRE on the FAS promoter.
Fatty acid specificity in the inhibition of cell proliferation and its relationship to lipid peroxidation and prostaglandin biosynthesisLipids - Tập 17 - Trang 893-899 - 1982
N. Morisaki, H. Sprecher, G. E. Milo, D. G. Cornwell
Primary cultures of smooth muscle cells were established from the medial layer of guinea pig aorta. Cells at passage level 4 were treated with different series of fatty acids belonging to the n-9, n-6 and n-3 families. Lipid peroxidation was measured by the thiobarbituric acid assay and prostaglandin biosynthesis was measured by the radioimmunoassay of PGE and 6-keto-PGF1α. Cell proliferation was estimated from the total cell number of cultures seeded at low density. 18∶1(n-9) did not form lipid peroxides and this fatty acid stimulated cell proliferation. All fatty acids which generated lipid peroxides inhibited cell proliferation, but inhibition was correlated with the degree of lipid peroxidation only in the n-9 fatty acid family. 22∶4(n-6) and 22∶6(n-3) inhibited prostaglandin biosynthesis. 18∶2(n-6), 18∶2(n-9), 18∶3(n-3), 20∶2(n-9), 20∶3(n-3) and 20∶5(n-3) had no effect on prostaglandin biosynthesis. 18∶3(n-6), 20∶3(n-6) and 20∶4(n-6) generated prostaglandins. 20∶3(n-9) generated metabolites with prostaglandin immunoreactivity. The inhibition of cell proliferation did not correlate with enhanced or inhibited prostaglandin synthesis. The inhibition of cell proliferation was related to the structures of the different polyunsaturated fatty acid families decreasing in the order n-9>n-6>n-3. Eicosatrienoic acids were the most effective inhibitors of cell proliferation in each fatty acid family and 20∶3(n-9) was the most potent eicosatrienoic acid. These data show that specific as yet unrecognized products of fatty acid metabolism are responsible for the inhibition of cell proliferation.
