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1.
Herbert C. Tidwell James C. McPherson Patricia Gifford 《Journal of the American Oil Chemists' Society》1965,42(10):843-845
The effect of the ingestion of large amounts of thetrans, trans isomer of linolein upon the cholesterol and lipid levels of the blood and liver was investigated using hypercholesterolemic
rats. The serum levels of esterified fatty acids and cholesterol of rats fed the diets containing 30% oftrans, trans linoleic acid glycerides and safflower oil were 15 and 25%, respectively, lower than those fed coconut oil. However, a weight
loss associated with less intake of thetrans isomer as compared with a gain with the other two fats must be considered. The serum levels of labeled cholesterol of rats
administered radioactive cholesterol along with thetrans isomer were intermediate in maximum value as compared to the levels obtained with coconut and safflower oils. These results
suggest that thetrans isomers are not as effective as thecis isomers in lowering the cholesterol and lipids of the blood. The livers of the former group had a lower fat content than
the latter which might be accounted for in part by the lower fat intake
Presented at AOCS Meeting, Houston, Texas, 1965. 相似文献
2.
《Applied catalysis. B, Environmental》2005,55(2):123-132
The photocatalytic oxidation of resorcinol, a potent endocrine disrupting chemical, in oxygenated aqueous suspensions of pure and cupric ions modified Degussa P25 titanium dioxide has been investigated at pH 3.0 ± 0.5. The initial rate of photocatalytic oxidation of resorcinol increased until an optimum dissolved cupric ions concentration was reached at 1.04 mM. At the optimum concentration of cupric ions, the initial rate of photocatalytic mineralisation and degradation of resorcinol was improved by 400%. The observed beneficial effect of cupric ions on the initial rate of resorcinol oxidation could be attributed to the formation of complex and its participation in the photoredox cyclic reaction.Two of the initial oxidation intermediates detected were 1,2,3-trihydroxybenzene and 1,2,4-trihydroxybenzene. These intermediates were formed via hydroxylation of the aromatic ring of resorcinol. Evidences have revealed that 1,2,4-trihydroxybenzene interacted strongly with cupric ions forming copper(II)-trihydroxybenzoate complexes that possessed good adsorption onto TiO2 surface. These dual-effects help to draw the metal ions closer to the photocatalyst surface and subsequently trigger the electron trapping mechanism by cupric ions. As a result, this improved the charge carriers’ separation. Furthermore, in the presence of oxygen, reoxidation of photoreduced cupric ions occurred and this eliminated the possibility of copper photodeposition, while inducing a photoredox cyclic reaction to regenerate copper species that may potentially act as co-catalyst for the oxidation of 1,2,4-trihydroxybenzene. In contrast, no obvious complex formation was seen between 1,2,3-trihydroxybenzene and cupric ions. This pointed to an intriguing finding which indicates that the positioning of functional group on benzene ring influences the role of cupric ions. 相似文献
3.
4.
The isolated perfused rat lung was used as an experimental model in the study of the lipoprotein regulation of surfactant
cholesterol metabolism. Addition of low density lipoproteins (LDL) to the perfusion medium at a cholesterol concentration
of 0.5 mM had no inhibitory effect on [1-14C]-acetate incorporation into cholesterol of either the surfactant or residual fractions. Increasing the concentration of
cholesterol in the medium to 2.5 mM resulted in significant inhibition of incorporation into cholesterol of both fractions.
A similar inhibition resulted when lungs were perfused with 2.5 mM cholesterol in the form of high density lipoproteins (HDL).
No inhibition of fatty acid synthesis, measured as incorporation into cholesteryl esters, was observed. The rate of uptake
by perfused lung of cholesterol from both high and low density lipoproteins was similar. Competitive binding studies with125I-labeled lipoproteins indicated the existence of lung receptors for both classes of lipoprotein. The rate of uptake of the
apoprotein moiety of low density lipoproteins was significantly greater than that of high density lipoproteins. These data
suggest that lung cholesterol metabolism may be subject to regulation by both low and high density serum lipoproteins. 相似文献
5.
The uptake of dolichol and cholesterol by perfused rat liver was studied. When these radioactive lipids were incorporated
into egg phosphatidylcholine liposomes, both dolichol and cholesterol appeared initially in the supernatant and in the microsomal
fraction and, later on, in the mitochondrial-lysosomal fraction. The lipids taken up were esterified to some extent, but no
phosphorylation of dolichol occurred. Incorporation of dolichol and cholesterol into lipoproteins increased the efficiency
of uptake, which was receptor-mediated in this case. Accumulation of these lipids occurred in lysosomes followed by a transport
to the endoplasmic reticulum (ER). Both labeled dolichol and cholesterol appeared in the bile. In the case of dolichol, the
majority of this radioactivity was not associated with the original substance itself, and probably represented lipid-soluble
catabolites. In the case of cholesterol, most of the radioactivity was associated with bile acids. It appears that, in contrast
to the receptor-mediated uptake of lipoproteins from the perfusate, the uptake of liposomal lipids involves a different mechanism.
After association with the plasma membrane, the lipids enter into the cytoplasm and are transported to the ER and later to
the lysosomes. 相似文献
6.
The exchange of surface protons on silica gel with cupric ions was investigated under two different conditions. The equilibrium constant was determined and the mechanism of the exchange was suggested. In ammonia water, two protons exchange with one tetrammine cupric ion and formed two ammonium ions. In acidic solution, where one proton exchanges with one cupric ion, the apparent equilibrium constant increases with an increase in the amount of copper loading. The structure of surface species on silica gel was suggested from the mechanism of the exchange and from ESR study. The surface species prepared in acidic solution is changed into the one prepared in ammonia water by exposure to ammonia. The change in the structure of surface species by the adsorption of foreign molecules was also studied. 相似文献
7.
Lin Yuan Wei‐Min Li Ling Jing Li‐Jun Zhou 《European Journal of Lipid Science and Technology》2010,112(8):821-827
Carnitine is known to be essential for metabolism regulation in some heart diseases such as coronary heart disease. We evaluated the effect of carnitine and valsartan on alcoholic cardiomyopathy (ACM); surprisingly, it was found that carnitine leads to variations in serum lipids. The results of our study, supported by cardiac function assessment, LVW/BW ratio, hematoxylin and eosin staining, and electron microscopic morphology, not only demonstrated the validity of our ACM model but also addressed the therapeutic benefits of carnitine and valsartan in antagonizing ACM development. The alcohol group displayed a high LVEDd and low EF and FS, indicating both heart failure and cardiac remodeling. Compared with the alcohol and alcohol/valsartan groups, the concentration of serum cholesterol in the alcohol/carnitine group was significantly increased between baseline and 6 months. The body weights of dogs from the alcohol group slowly increased between baseline and 6 months, although the LV weight increased quickly. The results suggest that both carnitine and valsartan have a favorable effect on ACM. However, the fact that carnitine could increase the serum cholesterol level should lead to caution in the treatment of ACM patients who are suffering from coronary disease in the meantime. 相似文献
8.
Sterol metabolism studies were carried out in rats maintained on a diet containing a polyene antibiotic, candicidin, (30 mg/kg/day)
for 2-1/2 months. Compared to the controls, the candicidintreated animals had a smaller food intake and weight gain during
this period. There was no difference between the 2 groups in serum cholesterol levels, biliary cholesterol or bile acid concentrations.
However, in the experimental group, liver cholesterol content decreased by 27% and hepatic HMG-CoA reductase increased by
36%. Candicidin administration produced an 84% increase in neutral sterol output without change in bile acid output. Cholesterol
absorption was reduced 80% by candicidin feeding. The weight of ventral prostate was reduced 33% by candicidin administration.
Prostatic HMG-CoA reductase levels were 3 times higher than those of the liver, but enzyme activity was unchanged by candicidin
treatment. 相似文献
9.
Glucose administered to fasted rats caused a marked stimulation in hepatic cholesterogenesis and cholesterol 7 alpha-hydroxylation, and an increase in biliary excretion of cholesterol and total bile acids. The excretion of cholic acid was not incluenced during the first few hr after glucose administration, but was significantly increased after 5 hr. Chenodeoxycholic acid showed a similar change, but the increase was only ca. one tenth of that of cholic acid. The excretion of deoxycholic acid was markedly increased by 1 hr, but gradually decreased thereafter. Pretreatment with neomycin abolished the increase in deoxycholic acid by fasting and glucose administration. Other bile acid components showed no significant change. It thus was presumed that cholesterol endogenously synthesized in the liver was metabolized mainly to cholic acid. In contrast, exogenous cholesterol was metabolized mainly to chenodeoxycholic acid. During the period of the acute enhancement of cholic acid formation from the endogenous cholesterol, biliary excretion of deoxycholic acid was increased. This probably occurred through the depression of 7 alpha-rehydroxylation of deoxycholic acid, or through the enhancement of microbial formation of deoxycholic acid in the lumen, and through the increase of intestinal absorption. 相似文献
10.
Dietary supplements containing cholesterol or sunflower oil were prepared to protect them against degradation in the rumen.
On feeding daily supplements containing 1–2 g protected cholesterol and/or 100g protected sunflower oil to sheep, along with
a basal ration of crushed oat grain and lucerne chaff, a rise in the plasma cholesterol was observed when compared with control
animals. Livers from sheep fed protected cholesterol were enlarged, friable and cirrhotic in appearance and contained large
deposits of esterified and free cholesterol, while livers from animals fed protected sunflower oil alone contained much less
cholesterol. Octadecenoates constituted the major fatty acids in cholesterol esters, which, in animals fed protected sunflower
oil, were mainly polyunsaturated. The factors involved in the deposition of liver lipid at very low dietary cholesterol concentrations
(0.11–22%) in sheep compared with monogastric animals are discussed.
Deceased. 相似文献
11.
The effects of aging on the hepatic metabolism of cholesterol were studied in 1-, 6- and 24-month-old male Sprague-Dawley
rats. Microsomal 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase activity, which regulates cholesterol biosynthesis,
decreased from 835±144 (SEM) pmol/min/mg protein in the youngest group to 219±34 and 205±53 pmol/min/mg protein (p<0.001)
in the 6- and 24-month-old groups, respectively. Cholesterol 7α-hydroxylase activity, which governs bile acid synthesis, was
gradually reduced from 70±14 pmol/min/mg protein in the 1-month-old group to 32±7 and 16±3 pmol/min/mg protein (p<0.05) in
the 6- and 24-month-old groups, respectively. Acyl coenzyme A:cholesterol acyltransferase activity, which catalyzes the esterification
of cholesterol, averaged 431±47 and 452 ±48 pmol/min/mg protein in the 1- and 6-month-old groups, respectively, and was increased
to 585±55 pmol/min/mg protein (p<0.05) in the 24-month-old group. The level of total cholesterol showed an age-related increase
from 1.56±0.16 mg/g liver in the 1-month-old group to 1.70±0.15 and 2.20±0.19 mg/g liver (p<0.05) in the 6- and 24-month-old
groups, respectively. The increase was mainly caused by an accumulation of esterified cholesterol. We conclude that a marked
decrease in HMG-CoA reductase occurs between 1 and 6 months of age; thereafter the enzyme activity stays unchanged. The activity
of cholesterol 7α-hydroxylase decreases progressively and drastically with age, whereas the capacity for esterifying cholesterol
increases slightly. We speculate that the reduced conversion of cholesterol to bile acids may be one explanation of the age-related
increase of plasma cholesterol seen in rats. 相似文献
12.
The effect of feeding cholesterol, taurocholic acid, or cholestyramine to chicks on cholesterolgenesis from [1-14C] acetate in liver and intestine was determined in vitro using tissue slices, and in vivo by i.v. injection of [14C] acetate. The conversion of cholesterol to bile acids in liver in vivo was measured in the same treatments after i.v. injection
of [3H] cholesterol. Hepatic cholesterogenesis in vitro and in vivo was depressed by dietary cholesterol and taurocholate and enhanced
by cholestyramine. Intestinal cholesterogenesis in vivo was depressed only by taurocholate whereas ileal cholesterogenesis
in vitro was reduced by dietary cholesterol. Conversion of cholesterol to bile acids was enhanced by dietary cholesterol and
cholestyramine and depressed by taurocholate. Hepatic cholesterol metabolism in the chick appears to be regulated by mechanisms
similar to those reported for other species. 相似文献
13.
Fibric acid derivatives are used to treat hyperlipidemia and have wide ranging effects on lipid metabolism. The action of
these compounds on cholesterol esterification, catalyzed by acyl-coenzyme A:cholesterol acyltransferase (ACAT), has been quite
widely studied, but their effect on cholesteryl ester hydrolysis and the enzyme neutral cholesteryl ester hydrolase (nCEH)
has been largely ignored. Male rats were therefore fed for 10 d on a standard chow diet supplemented with either clofibrate
or bezafibrate, to study their effects on plasma lipid levels and hepatic cholesterol metabolism. Plasma triacyglycerols were
not significantly altered by these diets, but bezafibrate significantly lowered plasma cholesterol levels (29.7%,P<0.01). When expressed per unit weight of DNA, both fibrates reduced the hepatic content of triacylglycerol, cholesterol and
cholesteryl esters (40, 18.7, 16.5 and 66.7, 28.6, 34.2% for clofibrate and bezafibrate, respectively). ACAT activity was
significantly reduced by both drugs, but clofibrate (65% inhibition) was more effective than bezafibrate (35% inhibition).
The most dramatic effect of the diets was a marked increase in the activity of both the microsomal and the cytosolic nCEH.
When expressed on a whole liver basis, the effect of bezafibrate on the cytosolic enzyme (13.6-fold increase in activity)
was much greater than that of clofibrate (4.8-fold increase). Increases in the activity of a cytosolic protein that inhibits
the activity of nCEH were also noted, but these changes were relatively small. The results suggest that the activation of
nCEH, in combination with the inhibition in ACAT activity, contributes to a decrease in the cholesteryl ester content of the
liver which may influence the secretion of very low density lipoprotein. 相似文献
14.
Serum and hepatic cholesterol content in rats treated with polychlorinated biphenyls (PCBs, KC-400) were increased compared
to those of control rats. This increase of cholesterol content was reduced to control level by simultaneous administration
of ethyl p-chlorophenoxyisobutyrate (CPIB). Also, when lecithin-cholesterol acyltransferase (LCAT) (EC. 2.3.1.43) activity
was expressed as the net cholesterol esterification, the acyltransferase activity in rats treated with PCBs was elevated,
while the elevated acyltransferase activity was brought to control level by simultaneous administration of CPIB. On the other
hand, the amount of bile of rats treated with CPIB, PCBs and PCBs-CPIB was increased, but free and total cholesterol content
in bile of these treated rats was decreased to 40–60% of those of control rats. Moreover, cytochrome P-450 content in liver
microsomes of rats treated with CPIB, PCBs and PCBs-CPIB was increased. At the same time, cholesterol-metabolizing activity
in liver microsomes of rats treated with CPIB, PCBs and PCBs-CPIB also was elevated. Similar results were obtained for drug
metabolizing (aniline hydroxylation and aminopyrine N-demethylation) activity. In addition, the amount of bile acids excreted
from rats treated with CPIB, PCBs and PCBs-CPIB was increased compared to that of control rats.
These results suggest that hypercholesterolemia induced by oral ingestion of PCBs is recovered by CPIB treatment and that
this hypocholesterolemic effect of CPIB may be related partly to the elevation of hepatic mixed function oxidase activity
for cholesterol catabolism. 相似文献
15.
Dagny Ståhlberg 《Lipids》1995,30(4):361-364
The effects of pregnenolone-16α-carbonitrile (PCN) on hepatic metabolism of cholesterol were studied in rat liver microsomes
in order to clarify the underlying mechanisms of the PCN-induced biliary hypersecretion of cholesterol. Male Sprague-Dawley
rats were fed a diet supplemented with 0.05% of PCN for one week. The microsomal activity of 3-hydroxy-3-methylglutaryl coenzyme
A reductase, regulating cholesterol biosynthesis, decreased from 577 ± 46 (SEM) to 367 ± 38 pmol/min/mg protein compared to
the controls. Cholesterol 7 α-hydroxylase activity, governing bile acid synthesis, was 9.0 ± 1.1 pmol/min/mg protein in the
treated group and 34.8 ± 7.4 pmol/min/mg protein in the controls, a reduction of 74% (P<0.01). The acyl CoA:cholesterol acyltransferase (ACAT) activity, catalyzing the esterification of cholesterol, remained unchanged,
as did the levels of total and free cholesterol in liver homogenates and microsomes. The results of this study provide evidence
that the increase in biliary cholesterol secretion during PCN treatment is not caused by a change in ACAT activity, but can
be explained by a decreased catabolism of cholesterol to bile acids. 相似文献
16.
Lipid biosynthesis was studied in vitro in liver, testes, and epididymal fat obtained from rats and rabbits fed di-(2-ethylhexyl)phthalate
for 4 weeks at levels of 0.5% and 1.0%, respectively. Several differences in response of the two species to DEHP feeding were
observed. In rats, but not in rabbits, DEHP feeding significantly reduced the incorporation of labeled mevalonic acid into
total sterols (p <0.02), digitonin-precipitable sterols (p<0.01), and squalene (p<0.05). Inhibition of hepatic sterologenesis
previously observed with DEHP feeding in the rat was also observed in the rabbit. In liver minces from the DEHP-fed rabbits,
incorporation of3H-mevalonic acid into C27 sterols (cholesterol) and C30 sterols (lanosterol) was significantly reduced by about 40% (p<0.05 and p<0.01, respectively), whereas the incorporation
of14C-glycerol 3-phosphate into phospholipids, and the combined fraction of monoglyceride + diglyceride, was significantly increased
(p<0.001 and p<0.01, respectively). In studies with epididymal fat, DEHP feeding did not affect the total incorporation of14C-acetate or3H-mevalonate into total saponifiable and nonsaponifiable lipids of either the rat or rabbit. However, in the rat, significantly
less of the14C-acetate (p<0.02) and3H-mevalonate (p<0.01) that was incorporated appeared in the combined fraction of cholesteryl ester + squalene. In addition,
DEHP feeding significantly reduced serum cholesterol (p<0.01) in the rat but not in the rabbit. The results of this study
indicate that DEHP feeding is associated with alterations in tissue lipid metabolism and that there are species differences
in the response of tissues to DEHP. 相似文献
17.
Chun-Yan Ou Si-Dong Li Cheng-Peng Li Chao-Hua Zhang Lei Yang Chong-Peng Chen 《应用聚合物科学杂志》2008,109(2):957-962
The thermal degradation of chitosan and chitosan–cupric ion compounds in nitrogen was studied by thermogravimetry analysis and differential thermal analysis (DTA) in the temperature range 30–600°C. The effect of cupric ion on the thermal degradation behaviors of chitosan was discussed. Fourier transform-infrared (FTIR) and X-ray diffractogram (XRD) analysis were utilized to determine the micro-structure of chitosan–cupric ion compounds. The results show that FTIR absorbance bands of N H, C N , C O C etc. groups of chitosan are shifted, and XRD peaks of chitosan located at 11.3, 17.8, and 22.8° are gradually absent with increasing weight fraction of cupric ion mixed in chitosan, which show that there are coordinating bonds between chitosan and cupric ion. The results of thermal analysis indicate that the thermal degradation of chitosan and chitosan–cupric ion compounds in nitrogen is a two-stage reaction. The first stage is the deacetylation of the main chain and the cleavage of glycosidic linkages of chitosan, and the second stage is the thermal destruction of pyranose ring of chitosan and the decomposition of residual carbon, in which both are exothermic. The effect of cupric ion on the thermal degradation of chitosan is significant. In the thermal degradation of chitosan–cupric ion compounds, the temperature of initial weight loss (Tst), the temperature of maximal weight loss rate (Tmax), that is, the peak temperature on the DTG curve, and the peak temperature (Tp) on the DTA curve decrease, and the reaction activation energy (Ea) varies with increasing weight fraction of cupric ion. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
18.
The non-lipid portions of semi-synthetic diets appear to be important determinants of hypercholesterolemia and atherosclerosis
in the rabbit. Serum and liver lipid concentrations were determined in rabbits which had been pair-fed various protein (casein
or soy protein isolate) and carbohydrate (sucrose or dextrose) sources as part of low fat, low cholesterol, semi-synthetic
diets. It was verified that caseincontaining diets render rabbits hypercholesterolemic, while soy protein caused a degree
of hypocholesterolemia. Additionally, sucrose, when fed in conjunction with casein, appears to augment this hypercholesterolemic
effect. The distribution of total cholesterol among lipoprotein subclasses was increased in both the intermediate density
lipoprotein (IDL) (1.006–1.019 g/ml) and low density lipoprotein (LDL) (1.019–1.063 g/ml) fractions and decreased in the high
density lipoprotein (HDL) (1.063–1.21 g/ml) fraction when casein is fed. Soy protein feeding caused relatively more cholesterol
to appear only in the IDL fraction when compared with commercial chow fed rabbits. Reasons for these differences may involve
the saturation or suppression of endogenous lipoprotein hepatic receptors. 相似文献
19.
Naoyuki Matoba Syoji Kuroki Bertram I. Cohen Erwin H. Mosbach Charles K. McSherry 《Lipids》1988,23(5):465-468
The effect of 7-methyl substituted bile acid and bile alcohol analogues on cholesterol metabolism was studied in the hamster.
Animals were fed chow plus 0.1% cholesterol supplemented with 0.1% of one of the following steroids: chenodeoxycholic acid,
7-methyl-chenodeoxy-cholic acid, 7β-methyl-24-nor-5β-cholestane-3α,7α,25-triol, cholic acid, 7-methyl-cholic acid, or 7β-methyl-24-nor-5β-cholestane-3α,7α,12α,25-tetrol.
Cholesterol absorption was determined from fecal analysis after feeding of radiolabeled cholesterol and β-sitosterol.
Of the six compounds studied, chenodeoxycholic acid and 7-methyl-chenodeoxycholic acid decreased intestinal cholesterol absorption
(17% and 31% decrease, respectively). Only 7-methyl-chenodeoxycholic acid decreased serum cholesterol concentration (29% decrease),
but there were no analogous changes of liver and biliary cholesterol concentration and cholesterol saturation of bile. Total
fecal neutral sterol excretion was increased in the groups fed chenodeoxycholic acid and 7-methyl-chenodeoxycholic acid. In
addition, the production of coprostanol was increased in both groups. These data suggest that 7-methyl-chenodeoxycholic acid
resembles chenodeoxycholic acid in its effect on cholesterol metabolism and may be a potential candidate for further studies
of its gallstone-dissolving properties. 相似文献
20.
Conversion of isotopic acetate to cholesterol, to fatty acids and to CO2 by rat liver homogenates is dramatically curtailed within 3 hr following injection of chloramphenicol or cycloheximide. Cholesterol
synthesis from mevalonate remains unaltered, indicating that this does not imply generalized depression of all metabolic processes.
This apparent shutdown of acetate metabolism suggests that caution be exercised when these drugs are employed as specific
inhibitors of protein synthesis.
Journal Paper No. 3631 of the Purdue University Agricultural Experiment Station. 相似文献