共查询到20条相似文献,搜索用时 15 毫秒
1.
Effect of chronic glucagon administration on lipoprotein composition in normally fed,fasted and cholesterol-fed rats 总被引:2,自引:0,他引:2
Catherine Guettet Najmuddin Rostaqui Denis Mathe Bernard Lecuyer Nicole Navarro Bernard Jacotot 《Lipids》1991,26(6):451-458
Male adult Wistar rats received daily (at 9 a.m. and 5 p.m.) 10 μg of zinc-protamine glucagon by subcutaneous injection for
8 days. Plasma cholesterol levels were decreased by 36% in fed rats, 33% in cholesterol-fed rats and by 55% in fasted rats.
Lipoproteins were separated into 22 fractions by ultracentrifugation using a density gradient. Glucagon administration decreased
the cholesterol content in all lipoproteins except low density lipoprotein (LDL1) (1.006–1.040) and very low density lipoprotein (VLDL) from cholesterol-fed rats. The main decrease (−57 to −81%) was observed
in 1.050–1.100 g/mL lipoproteins (LDL2 and HDL2), which contained a large amount of apo E, while HDL3 cholesterol was not affected. Triacylglycerol levels were decreased only in chylomicrons and VLDL (−70%) of fed and cholesterol-fed
rats, while plasma and lipoprotein triacylglycerol levels were not changed in fasted rats treated with glucagon. In normally
fed rats glucagon administration increased by 42% the fractional catabolic rate of [125I]HDL2 while the absolute catabolic rate appeared to be unchanged. Glucagon seems to be a potent hypolipidemic agent affecting mainly
the apo E-rich lipoproteins. Its chronic administration limits lipoprotein accumulation which occurs upon cholesterol feeding. 相似文献
2.
Cholesterol gallstone induction in hamsters reflects strain differences in plasma lipoproteins and bile acid profiles 总被引:4,自引:4,他引:0
Because different strains of hamsters vary in their susceptibility to gallstones, the relationship between plasma lipoproteins,
hepatic cholesterol, bile lipids and bile acid profile was examined during gallstone induction in strains of male Syrian hamsters
from Charles River Lakeview (CHR), Biobreeder F1B (BIO) and Harlan Sprague-Dawley (HAR). Gallstones were induced by feeding a purified diet containing 0.4 or 0.8% cholesterol
for 5 wk. Basal plasma total cholesterol was similar, but the hypercholesterolemia induced by dietary challenge was significantly
lower in CHR than in HAR and BIO hamsters. Cholesterol-fed CHR hamsters transported cholesterol mainly in HDL (47%), whereas
VLDL-C+IDL-C predominated in BIO and HAR hamsters, and their HDL transported only 28 and 38%, respectively. HAR hamsters accumulated
the most hepatic cholesterol, revealed the highest cholate/cheno ratio, the lowest glycine/taurine ratio and hydrophobicity
index. HAR also developed the fewest cholesterol gallstones (23%), while 64% of CHR and 58% of BIO hamsters had cholesterol
gallstones and 34% of BIO hamsters developed pigment stones. Doubling dietary cholesterol from 0.4 to 0.8% doubled the incidence
of cholesterol gallstones but exerted minimal impact on other parameters compared to strain differences. Thus, different strains
of hamsters vary considerably with respect to biliary cholesterol, bile acid profile and formation of cholesterol gallstones
associated with differences in plasma lipoprotein profiles. 相似文献
3.
The objective of this study was to determine the effects of various dietary animal (casein, bovine albumin and egg albumin)
and vegetable (soy, cottonseed and peanut) proteins on serum and biliary constitutents and gallstone formation in the hamster.
Eighty-four hamsters (60±5g) were assigned to either a control group (Purina rat chow) or to one of the 6 experimental groups.
Experimental diets contained 20.0% protein. With the exception of hamsters fed egg albumin, gallstone incidence was greater
among hamsters fed animal proteins. Hamsters fed egg albumin exhibited a lower concentration of total serum cholesterol and
HDL-cholesterol than most of the other experimental groups. There were no significant differences between experimental groups
for either HDL3-cholesterol concentration or VLDL-LDL-cholesterol concentration. Bile acid concentrations within the vegetable protein-fed
groups were significantly higher than within the animal protein-fed groups. Casein- and bovine albumin-fed hamsters showed
a significantly higher percentage of biliary cholesterol in the bile fluid. As the percentage of biliary cholesterol increased,
the percentage of bile acids was found to decrease.
Preliminary reports of portions of this work were presented at the 74th Annual Meeting of the American Oil Chemist’s Society
in May 1983 in Chicago. 相似文献
4.
Bertram I. Cohen Takahiro Mikami Nariman Ayyad Yasuko Mikami Erwin H. Mosbach 《Lipids》1995,30(4):299-305
The type of dietary fat strongly affects the incidence of gallstones in the hamster model of cholesterol cholelithiasis. The
present study was designed to determine whether dietary fats could affect gallstone formation by altering the microstructure
(vesicular/micellar ratio) of cholesterol in bile. Golden Syrian hamsters from Sasco (Omaha, NE) or Charles River (Wilmington,
MA) were fed nutritionally adequate semipurified diets to which were added: (i) 4.0% butterfat without added cholesterol;
(ii) 1.2% palmitic acid plus 0.3% cholesterol; or (iii) 4.0% safflower oil plus 0.3% cholesterol. Gallstone incidence and
the percentage of cholesterol in vesicles and micelles were determined after two- or six-week feeding periods. Three out of
ten Sasco hamsters fed the 1.2% palmitic acid diet for two weeks had cholesterol stones, while none of the eight Charles River
animals had stones. In the Sasco hamsters, a significant proportion of the biliary cholesterol was found in void volume vesicles
(28.8%) and small vesicles (17.1%); Charles River hamsters had negligible proportions (1.1%) of cholesterol in void volume
vesicles and 15.4% in small vesicles. Cholesterol gallstones were most abundant in Sasco hamsters fed 1.2% palmitic acid for
six weeks (nine out of ten animals); the mean cholesterol saturation index of the bile was 1.27. A significant proportion
of the biliary cholesterol was eluted in the void volume vesicles (21.4%) and in small vesicles (15.0%). Five of the eight
identically treated Charles River hamsters had cholesterol stones; the cholesterol saturation index averaged 1.36, and the
biliary cholesterol was present in void volume vesicles (31.3%) and small vesicles (14.3%). Vesicles were not detected in
the bile of hamsters fed cholesterol-free diets, and none of these animals developed cholesterol gallstones. Safflower oil
diets inhibited stone formation even though the cholesterol saturation index was above unity. After six weeks, biliary cholesterol
transported in void volume vesicles was highest for Sasco hamsters (13.3%) as compared to Charles River animals (6.9%), but
total cholesterol transported in void volume vesicles plus small vesicles was similar in both groups (33.5% vs. 26.2%), respectively.
These results suggest that in both strains of hamsters dietary fat influences gallstone formation by modulating the vesicular/micellar
distribution of biliary cholesterol. Apparently, the presence of cholesterol/phospholipid vesicles in bile is associated with
cholesterol gallstone formation. 相似文献
5.
Takahiro Mikami Bertram I. Cohen Yasuko Mikami Nariman Ayyad Erwin H. Mosbach 《Lipids》1994,29(8):529-534
The distribution of cholesterol among its carriers was studied in the bile of male and female hamsters. Sasco hamsters (Sasco
Inc., Omaha, NE) were fed a semipurified diet with 0.0% cholesterol and 4% butterfat (group 1, males; group 4, females); a
semipurified diet with 0.3% cholesterol and 1.2% plamitic acid (group 2, males; group 5, females); and a semipirified diet
with 0.3% cholesterol and 4% safflower oil (group 3, males; group 6, females). At the end of six weeks, gallstones were found
only in male hamsters receiving both cholesterol and dietary fat (fatty acid) (incidence of cholesterol stones: 90% in group
2; 22% in group 3). The biliary cholesterol carriers were separated and isolated from the bile of the hamsters by gel filtration
chromatography, using the method of Pattinson [Pattinson, N.R., Willis, K.E., and Frampton, C.M. (1991)J. Lipid Res. 32, 205–214]. In those male hamsters that formed cholesterol gallstones, significant amounts of cholesterol were present in
the void volume which contained large cholesterol phospholipid vesicles (void volume vesicles) (23% in group 2 and 15% in
group 3). Smaller cholesterol/phospholipid vesicles were eluted next (fractions 30–45) and contained 15% of biliary cholesterol
in group 2 and 21% in group 3. The remainder of the cholesterol was associated with mixed cholesterol/phospholipid/bile salt
micelles. The cholesterol/phospholipid ratio was larger in both the void volume vesicles and small vesicles (2.40 and 1.48
in group 2; 2.56 and 1.33 in group 3, respectively) compared to the micelles (about 0.3 in groups 2 and 3). In contrast, the
bile of the female hasmters contained few vesicles (3% small vesciles in group 5) and the cholesterol/phospholipid ratio of
these vesicles was lower (0.94). Hamsters fed cholesterol-free diets (groups 1 and 4) had no biliary cholesterol/phospholipid
vesilces; and cholesterol was present in micelles. The results suggest that both the gender and the diet of the hamsters affected
the distribution of biliary cholesterol between vesicles and micelles. The development of cholelithiasis in this animal model
appears to depend on the rapid nucleation of cholesterol-rich phospholipid vesicles in bile. 相似文献
6.
Arne T. Høstmark Øystein Spydevold Einar Lystad Eva Kristensen Ida Goffeng Bay 《Lipids》1982,17(7):489-499
The effect of varying the dietary sunflower oil/sucrose (SO/SU) ratio on rat plasma lipid concentration and lipoprotein distribution
was studied. Four groups of 10 rats were fed for 4 weeks diets with varying SO/SU ratios. Lipoprotein components were then
estimated in whole plasma and after cumulative density ultracentrifugation. Whole plasma triacylglycerol (TG), total cholesterol
(TC) and free cholesterol (FC) decreased with increasing SO/SU ratio; the CE/FC ratio increased, because CE remained virtually
unaltered. Plasma TG-lowering was due to a decrease in VLDL and LDL-TG. Protein, CE and FC in d=1.063–1.100 g/ml (HDL2b) and d=1.100–1.125 g/ml (HDL2a) lipoproteins decreased upon increasing the SO/SU ratio. In contrast, in d=1.125–1.200 g/ml (HDL3) lipoproteins, there was a concomitant increase in these components. Although increasing the SO/SU ratio effected more protein
and CE transportation in HDL3 and less in HDL2, the total amount of these components in high density lipoproteins (d=1.063–1.200 g/ml) remained constant. Apo A-I and apo
C-III decreased in HDL2 but increased in HDL3 upon increasing the SO/SU ratio. Also, HDL2 apo E, and the apo C-II/apo C-III and small apo B/large apo B ratios in VLDL and LDL were lowered by increasing the SO/SU
ratio. The hepatic VLDL-TG output during isolated liver perfusion was lowest in rats fed the diet with the highest SO/SU ratio.
In perfusate, like in plasma, the VLDL and LDL apo C-II/apo C-III ratio, as well as the small apo B/large apo B ratio, decreased
upon increasing the dietary SO/SU ratio. The results indicate that there can be appreciable diet-dependent variations in plasma
HDL subgroup distribution in spite of unchanged total HDL levels. 相似文献
7.
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. 相似文献
8.
The aim of the present study was to characterize plasma lipids and lipoprotein cholesterol and glucose concentrations in hamsters
fed either cis-9, trans-11 CLA (9c, 11t CLA); trans-10, cis-12 CLA (10t, 12c CLA); or linoleic acid (LA) on the accumulation of aortic cholesterol in hypercholesterolemic hamsters. One hundred male
F1B strain Syrian Golden Hamsters (Mesocricetus auratus) (BioBreeders Inc., Watertown, MA) approximately 9 wk of age were housed in individual stainless stel hanging cages at room
temperature with a 12-h light/dark cycle. Hamsters were given food and water ad libitum. Following a 1-wk period of acclimation, the hamsters were fed a chow-based (nonpurified) hypercholesterolemic diet (HCD)
contaning 10% coconut oil (92% saturated fat) and 0.1% cholesterol for 2 wk. After an overnight fast, the hamsters were bled
and plasma cholesterol concentrations were measured. The hamsters were then divided into 4 groups of 25 based on similar mean
plasma VLDL and LDL cholesterol (non HDL-C) concentrations. Group 1 remained on the HCD (control). Group 2 was fed the HCD plus 0.5% 9c, 11t CLA isomer. Group 3 was fed the HCD plus 0.5% 10t, 12c CLA isomer. Group 4 was fed the HCD plus 0.5% LA. Compared with the control, both CLA isomers and LA had significantly lower
plasma total cholesterol and HDL cholesterol concentrations (P<0.001) after 12 but not 8 wk of treatment and were not significantly different from each other. Also, both CLA isomers had
significantly lower plasma non HDL-C concentrations (P<0.01) compared with the control after 12 but not 8 wk of treatment and were not significantly different from each other or
the LA-fed hamsters. Plasma TG concentrations were significantly higher (P<0.004) with the 10t, 12c CLA isomer compared with the other treatments at 8 but not at 12 wk of treatment. Plasma TG concentrations were also significantly
lower (P<0.03) with the 9c, 11t CLA isomer compared with the control at 12 wk of treatment. Also, the 10t, 12c CLA isomer and LA had significantly higher plasma glucose concentrations compared with the control and 9c, 11t CLA isomer (P<0.008) at 12 wk of treatment whereas at 8 wk, only the LA treatment had significantly higher plasma glucose concentrations
(P<0.001) compared with the 9c, 11t CLA isomer. Although liver weights were significantly higher in 10t, 12c CLA isomer-fed hamsters, liver total cholesterol, free cholesterol, cholesterol ester, and TG concentrations were significantly
lower in these hamsters compared with hamsters fed the control, 9c, 11t CLA isomer, and LA diets (P<0.05). The 9c, 11t CLA isomer and LA diets tended to reduce cholesterol accumulation in the aortic arch, whereas the 10t, 12c CLA isomer diet tended to raise cholesterol accumulation compared with the control diet; however, neither was significant.
In summary, no differences were observed between the CLA isomers for changes in plasma lipids or lipoprotein cholesterol concentrations.
However, the 9c, 11t CLA isomer did appear to lower plasma TG and glucose concentrations compared with the 10t, 12c CLA isomer. Such differences may increase the risk of insulin resistance and type 2 diabetes in humans when the 10t, 12c CLA isomer is fed separately. 相似文献
9.
Nariman Ayyad Bertram I. Cohen Erwin H. Mosbach Shigeo Miki Takahiro Mikami Yasuko Mikami Richard J. Stenger 《Lipids》1993,28(11):981-986
In the present study, we examined the effect of the following factors on a hamster model of cholesterol cholelithiasis: (i)
the source of the golden Syrian hamsters (Sasco, Omaha, NE or Charles River, Wilmington, MA), (ii) the sex of the experimental
animals and (iii) their age (4 wkvs. 8 wk of age). All hamsters were fed a semipurified diet which contained cholesterol (0.3%) and palmitic acid (1.2%). No cholesterol
gallstones formed in any of the female hamsters regardless of age or source. The 4-week-old male hamsters from Sasco had the
greatest incidence of gallstones (93%). The 8-week-old male hamsters tended to have a lower incidence of cholesterol gallstones
than the younger ones, regardless of the commercial supplier (67vs. 93% for Sasco and 27vs. 40% for Charles River). Female hamsters has higher liver and serum cholesterol levels than the male hamsters; Charles River
hamsters had lower serum cholesterol concentrations than the Sasco animals. Total biliary lipid concentrations were highest
in Sasco male hamsters, but biliary cholesterol (mol%) was lower in the males than in the females (4.2–4.5%vs. 6.1–7.1%) regardless of age. The cholesterol saturation indices were higher in the Sasco females than the corresponding males;
these values were lower in the Sasco hamsters than the Charles River animals, regardless of age or sex. The male Sasco hamsters
had a higher total biliary bile acid concentration (98.9 mg/mL) than the Sasco females (58.9 mg/mL) and the Charles River
animals (24.6% mg/mL for males and 38.2 mg/mL for females). The percentage of chenodeoxycholic acid in bile was significantly
lower, and the percentage of cholic acid was higher in all females as compared to males. We conclude that there is a sex,
age and “strain” difference in cholesterol cholelithiasis in hamsters; it is important to consider these factors when working
with the hamster model of gallstone disease. All female hamsters were markedly resistant to the induction of cholesterol gallstone
disease. 相似文献
10.
While it is known that the transfer of cholesteryl ester (CE) from high density lipoprotein (HDL) to the apo B-containing
lipoproteins is increased in patients with diabetes, the extent to which the various lipoprotein fractions engage in neutral
lipid exchange and the magnitude to which triglyceride (TG) is translocated is not known. To examine in greater detail neutral
lipid net mass transfer in diabetes, the HDL subfractions and the apo B-containing lipoproteins were separated, and the net
mass transfer of CE and TG was compared to that of control subjects. In both groups, bidirectional transfer of CE from HDL3 to very low density lipoprotein (VLDL) + low density lipoprotein (LDL) and of TG from VLDL+LDL to HDL3, took place, but this process was significantly greater (P<.01) in insulin-dependent diabetes mellitus (IDDM). In contrast, CE and TG accumulated in HDL2 to a similar degree in normal and IDDM subjects. In recombination experiments with each of the apo B-containing lipoproteins,
IDDM VLDL had a greater capacity to facilitate the exchange of core lipids from both IDDM and control HDL3: on the other hand, LDL from IDDM and control subjects both donated TG and CE to HDL2 and affected little change in HDL3. These findings indicate that all the major plasma fractions normally participate in the trafficking of CE and TG among the
lipoproteins during neutral lipid transfer and show that the principal perturbation in cholesteryl ester transfer in IDDM
involves altered interaction between VLDL and the HDL3 subfraction. 相似文献
11.
This study was designed to determine whether incorporation of γ-tocotrienol or α-tocopherol in an atherogenic diet would reduce
the concentration of plasma cholesterol, triglycerides and fatty acid peroxides, and attenuate platelet aggregability in rats.
For six weeks, male Wistar rats (n=90) were fed AIN76A semisynthetic test diets containing cholesterol (2% by weight), providing
fat as partially hydrogenated soybean oil (20% by weight), menhaden oil (20%) or corn oil (2%). Feeding the ration with menhaden
oil resulted in the highest concentrations of plasma cholesterol, low and very low density lipoprotein cholesterol, triglycerides,
thiobarbituric acid reactive substances and fatty acid hydroperoxides. Consumption of the ration containing γ-tocotrienol
(50 μ/kg) and α-tocopherol (500 mg/kg) for six weeks led to decreased plasma lipid concentrations. Plasma cholesterol, low
and very low density lipoprotein cholesterol, and triglycerides each decreased significantly (P<0.001). Plasma thiobarbituric acid reactive substances decreased significantly (P<0.01), as did the fatty acid hydroperoxides (P<0.05), when the diet contained both chromanols. Supplementation with γ-tocotrienol resulted in similar, though quantitatively
smaller, decrements in these plasma values. Plasma α-tocopherol concentrations were lowest in rats fed menhaden oil without
either chromanol. Though plasma α-tocopherol did not rise with γ-tocotrienol supplementation at 50 mg/kg, γ-tocotrienol at
100 mg/kg of ration spared plasma α-tocopherol, which rose from 0.60±0.2 to 1.34±0.4 mg/dL (P<0.05). The highest concentration of α-tocopherol was measured in plasma of animals fed a ration supplemented with α-tocopherol
at 500 mg/kg. In response to added collagen, the partially hydrogenated soybean oil diet without supplementary cholesterol
led to reduced platelet aggregation as compared with the cholesterol-supplemented diet. However, γ-tocotrienol at a level
of 50 mg/kg in the cholesterol-supplemented diet did not significantly reduce platelet aggregation. Platelets from animals
fed the menhaden oil diet released less adenosine triphosphate than the ones from any other diet group. The data suggest that
the combination of γ-tocotrienol and α-tocopherol, as present in palm oil distillates, deserves further evaluation as a potential
hypolipemic agent in hyperlipemic humans at atherogenic risk. 相似文献
12.
The content and structure of glycosphingolipids (GSL) in human plasma lipoproteins were studies. The quantitative distribution
of the neutral GSL(Glc-Cer, Gal-Glc-Cer, Gal-Gal-Glc-Cer, and GalNAc-Gal-Gal-Glc-Cer) and the principal ganglioside (AcNeu-Gal-Glc-Cer)
within the different lipoprotein classes was similar to that of whole plasma. The total amounts (μmol glucose/100 ml plasma)
of GSL in the plasma lipoproteins of three normal subjects were VLDL (very low density lipoproteins) (trace to 0.46), LDL
(low density lipoproteins) (1.08–1.48), HDL2 (high density lipoproteins2) (0.62–0.85), and HDL3 (high density lipoproteins3) (trace to 0.28). In subjects with Lp(a) lipoproteins, HDL2 rather than HDL3 contained most of the GSL in HDL. When the data were corrected for differences in the plasma concentrations of the lipoproteins,
the total amounts of GSL(nmol glucose/mg lipoprotein cholesterol) were VLDL(trace to 21.20), LDL(11.70–15.36), HDL2(8.50–9.10), and HDL3(3.12). No GSL were detected in lipoprotein deficient plasma. Mass spectrometry of the trimethylsilyl derivatives of the GSL
in LDL showed major fragment ions characteristic of their individual structural components. The elevated plasma levels of
the GSL(2–18 fold), in a homozygote for familial hypercholesterolemia, resided in LDL which contained an absolute increase
(per mg lipoprotein cholesterol) of GSL. Most, if not all, of the plasma GSL are associated with plasma lipoproteins and may
have an important role in their biological functions. 相似文献
13.
Bertram I. Cohen Takahiro Mikami Nariman Ayyad Akira Ohshima R. Infante Erwin H. Mosbach 《Lipids》1995,30(9):855-861
The effects of β-muricholic acid and hyocholic acid on cholesterol cholelithiasis were examined in two animal models. The
following experiments were carried out: A) In a gallstone prevention study, prairie dogs were fed the lithogenic diet with
or without 0.1% β-muricholic or 0.1% hyocholic acid for eight weeks. B) In a second prevention study, hamsters were fed the
lithogenic diet with or without 0.1% β-muricholic acid or 0.1% hyocholic acid for six weeks. C) In a gallstone dissolution
study, hamsters were fed the lithogenic diet for six weeks to induce stones; stone dissolution was examined during administration
of a cholesterol-free purified diet with or without 0.1% β-muricholic acid or 0.1% hyocholic acid. In the prevention study
in prairie dogs (A), both bile acids failed to prevent stone formation, the cholesterol saturation index of bile was 0.89
in the lithogenic controls, remained unchanged with hyocholic acid and increased to 1.52 in the β-muricholic acid group. In
the prevention study in hamsters (B), β-muricholic acid completely inhibited the cholesterol cholelithiasis (0% stone incidence);
the cholesterol saturation index of bile was 1.78 (compared to lithogenic controls, 1.37). Hyocholic acid reduced stone incidence
to 16% with a cholesterol saturation index of 0.98. In the dissolution study in hamsters (C), preexisting cholesterol gallstones
were not dissolved by either hydrophilic bile acid after feeding these bile acids for an additional six weeks; at the end
of the experiment, the cholesterol saturation indices were below unity. These studies suggest that, in the hamster animal
model, hydrophilic bile acids may be useful for the prevention of gallstones but not dissolution of preestablished cholesterol
gallstones. 相似文献
14.
Eicosapentaenoic acid is primarily responsible for hypotriglyceridemic effect of fish oil in humans 总被引:4,自引:0,他引:4
The aim of this study was to determine whether eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA), or both, were responsible
for the triglyceride (TG)-lowering effects of fish oil. EPA (91% pure) and DHA (83% pure), a fish oil concentrate (FOC; 41%
EPA and 23% DHA) and an olive oil (OO) placebo (all ethyl esters) were tested. A total of 49 normolipidemic subjects participated.
Each subject was given placebo for 2–3 wk and one of the n-3 supplements for 3 wk in randomized, blinded trials. The target
n-3 fatty acid (FA) intake was 3 g/day in all studies. Blood samples were drawn twice at the end of each supplementation phase
and analyzed for lipids, lipoproteins, and phospholipid FA composition. In all groups, the phospholipid FA composition changed
to reflect the n-3 FA given. On DHA supplementation, EPA levels increased to a small but significant extent, suggesting that
some retroconversion may have occurred. EPA supplementation did not raise DHA levels, however, FOC and EPA produced significant
decreases in both TG and very low density lipoprotein (VLDL) cholesterol (C) levels (P<0.01) and increases in low density lipoprotein (LDL) cholesterol levels (P<0.05). DHA supplementation did not affect cholesterol, triglyceride, VLDL, LDL, or high density lipoprotein (HDL) levels,
but it did cause a significant increase in the HDL2/HDL3 cholesterol ratio. We conclude that EPA appears to be primarily responsible for TG-lowering (and LDL-C raising) effects of
fish oil. 相似文献
15.
Dietary fat alters biliary lipid secretion in the hamster 总被引:1,自引:0,他引:1
Dietary fat has been found to alter the incidence of cholesterol gallstones in hamsters: butterfat intensifies while safflower
oil reduces lithiasis. We now report how dietary fat affects bile flow and biliary lipid secretion in this model. Male hamsters
were fed one of three experimental diets: a control diet (containing 0.3% cholesterol); control diet +4.0% butterfat; or control
diet +4.0% safflower oil. After three weeks, bile samples were collected via an external biliary fistula. The endogenous bile
acid pool was depleted for 120 min followed by increasing rates of taurocholate infusion for 160 min. Basal secretion of biliary
lipids was measured during the bile acid depletion period. Basal bile flow and bile acid output were not significantly different
in the three groups. Dietary butterfat increased basal cholesterol output compared to the control diet (0.037 vs. 0.025 μmol/min·kg,
respectively); safflower oil did not change cholesterol output (0.027 μmol/min·kg). Hamsters fed butterfat or safflower oil
secreted more phospholipid (0.171 and 0.178 μmol/min·kg, respectively) than controls (0.131 μmol/min·kg). The cholesterol/phospholipid
output ratio of the butterfat group was higher than the safflower oil group (0.220 vs. 0.153, respectively). Effects of dietary
fat on several relationships between bile flow and biliary lipid secretion were analyzed by linear regression using the data
for the entire bile collection period (bile acid depletion and taurocholate infusion). Butterfat and safflower oil did not
change either bile acid dependent or bile acid independent bile flow. Hamsters fed butterfat had a higher linkage coefficient
(slope) of cholesterol vs. bile acid output than the safflower oil group (0.023 vs. 0.009, respectively). The linkage coefficient
of phospholipid vs. bile acid output of the butterfat group was higher than the controls (0.278 vs. 0.185, respectively).
In summary, butterfat induced a high cholesterol and phospholipid secretion with a high cholesterol/phospholipid output ratio;
safflower oil induced a high phospholipid secretion with a low cholesterol/phospholipid output ratio. Butterfat and safflower
oil have different effects on biliary lipid secretion. These differences in biliary lipid secretion may explain, in part,
how butterfat and safflower oil differ in affecting gallstone formation in hamsters. 相似文献
16.
M. A. Sullivan-Gorman J. M. Anderson N. M. DiMarco J. Johnson I. Chen J. Ashby G. U. Liepa 《Journal of the American Oil Chemists' Society》1987,64(8):1196-1199
The objective of this experiment was to study the effects of dietary cottonseed protein and casein on plasma and biliary lipids,
plasma amino acids and gallstones in hamsters. Thirty-four male hamsters (60 ± 5 g) were fed either the lithogenic “Dam Diet”
(containing 20% casein, 74.3% sucrose and 5.7% vitamin-mineral mix) or a similar diet that contained 20% cottonseed protein
for 30 days. Both diets contained protein as a protein isolate. The concentration of alpha-aminobutyric acid was significantly
elevated in the casein-fed group. Significant differences in the total plasma cholesterol or lipoprotein cholesterol concentrations
were not observed between the two dietary groups.
A significant elevation in the absolute concentration of biliary cholesterol was observed in the casein-fed hamsters. Cottonseed
protein-fed animals exhibited a significantly elevated concentration of bile acids. The ratio of glycochenodeoxycholic:glycocholic
acid was significantly higher in the cotton-seed protein-fed group. This study reports that an elevated concentration of biliary
cholesterol with a concomitant decrease in bile acid concentration yields a condition favorable to gallstone formation. It
is proposed that cottonseed protein may have a specific effect on the bile acid pool by increasing the ratio of glycochenodeoxycholic
acid:glycocholic acid which, in turn, prevents formation of cholesterol gallstones. 相似文献
17.
Lipid and apolipoprotein (apo) A-I concentrations in different density fractions of New Zealand White (NZW) and Watanabe (WHHL)
rabbit plasma were studied. Aside from the low plasma apoA-I and high density lipoprotein (HDL) cholesterol levels in WHHL
rabbits, the distribution of apoA-I was also different between the two rabbits. ApoA-I was concentrated in both the HDL2 and HDL3 fractions of NZW rabbits but was found primarily in the HDL3 fraction of WHHL rabbits. ApoA-I secretion in these two rabbits was further studiedin vitro by using intestinal and hepatocyte cell cultures. ApoA-I secretion was highest from cultures of the duodenum and the proximal
end of the jejunum; whereas, cell cultures of the distal end of the small intestine secreted very little apoA-I into the medium.
Intestinal cell cultures from WHHL rabbits secreted less, but significant amounts of, apoA-I compared to that of NZW rabbits.
ApoA-I was most concentrated in the density range of 1.12–1.21 (HDL3) fraction in medium containing 10% fetal calf serum (FCS). Serum-free medium promoted apoA-I secretion by intestinal cell
cultures that was mostly found in the d>1.21 (lipoprotein-deficient) fraction. Hepatocytes isolated from the same rabbits
by collagenase perfusion secreted little apoA-I, and it was found only in the d>1.21 fraction. The addition of oleic acid
into the culture medium with 10% FCS decreased the secretion of total apoA-I and HDL by intestinal cell cultures and increased
the secretion of very low density lipoprotein (VLDL) and intermediate density lipoproteins (IDL). The results indicate that
intestinal cells, not hepatocytes, are responsible for the secretion of apoA-I and HDL3 in rabbits, and that the secretion may be regulated under different nutritional conditions. 相似文献
18.
The influence of dietary excess (5%) of L-cystine on rat plasma lipoproteins was examined. After only one week of cystine
feeding, an increase in the plasma cholesterol level and a decrease in triglyceride levels were observed. The increase in
cholesterol level became greater when the duration of cystine-enriched diet increased until eight weeks (+131% after eight
weeks), but no further increase occurred between 8 and 20 weeks. This change was essentially due to the progressive increase
in cholesterol levels in high density lipoproteins (HDL) and in lipoproteins isolated between 1.040 and 1.063 g/ml, i.e.,
certain low density lipoproteins (HDL2), and containing mainly apoE-rich lipoproteins (HDL1). The decrease in plasma triglycerides resulted from that of chylomicrons and very low density lipoproteins (VLDL). The effects
observed after four or eight weeks of cystine feeding were maintained for eight weeks after replacing the cystine diet by
the standard diet. Ingestion of the standard diet containing either cholestyramine (2%) or probucol (0.25%) following eight
weeks of cystine feeding significantly decreased plasma cholesterol levels. It is concluded that cystine-fed rats are a useful
tool of investigation for understanding mechanisms leading to increased plasma cholesterol level and for hypocholesterolemic
drug trials. 相似文献
19.
Bertram I. Cohen Naoyuki Matoba Erwin H. Mosbach Richard J. Stenger Charles K. McSherry 《Lipids》1989,24(6):482-487
Dietary cholic acid (0.1%) and/or calcium (2.6% as calcium carbonate) were added to a semipurified diet containing cholesterol
and ethynyl estradiol to determine whether the incidence of pigment and/or cholesterol gallstones would be changed. Male golden
Syrian hamsters were fed the experimental diets for 96 days (Group 1, control; Group 3, cholic acid plus calcium) or only
an average of 60 days (Group 2, 0.1% cholic acid). Animals in Group 2 became ill (weight loss, low food intake, diarrhea)
possibly due to cholic acid (or deoxycholic acid) toxicity. Cholesterol gallstones and crystals were absent in all experimental
groups. The incidence of pigment gallstones was: control, Group 1, 12/16; 0.1% cholic acid, Group 2, 3/13; and 0.1% cholic
acid plus calcium, Group 3, 11/22. Cholic acid with or without calcium produced an elevation of both liver and plasma cholesterol:
Group 2, 80.1 mg/g and 501 mg/dl; Group 3, 103.7 mg/g and 475 mg/dl vs Group 1, 65 mg/g and 209 mg/dl, respectively. The lithogenic
indices of the bile were lower in Groups 2 and 3 compared to Group 1, controls, 0.45 and 0.58 vs 1.16, respectively. The extent
of the portal tract pathology could not be correlated with the presence or absence of pigment gallstones or with the levels
of lithocholic acid in the hamster bile. In summary, when semipurified diets were supplemented with ethynyl estradiol and
cholic acid, with and without calcium supplementation, no cholesterol gallstones formed and the incidence of pigment gallstones
was not altered. 相似文献
20.
Ernst J. Schaefer David M. Foster Leslie L. Jenkins Frank T. Lindgren Mones Berman Robert I. Levy H. Bryan Brewer Jr. 《Lipids》1979,14(5):511-522
The composition and metabolism of high density lipoprotein (HDL) subfractions were investigated in seven nomal individuals.
Mean HDL2 (d, 1.063–1.125 g/ml) composition (by weight) was 43% protein, 28% phospholipid, 23% cholesterol, and 6% triglyceride, and
mean HDL3 (d, 1.125–1.21 g/ml) composition was 58% protein, 22% phospholipid, 14% cholesterol, and 5% triglyceride. The mean apoA-I;
apoA-II weight ratio was 4.75 for HDL2 and 3.65 for HDL3.HDL2 protein was proportionally slightly richer in C apolipoproteins and higher molecular weight constituents (including apoE)
than HDL3. Kinetic studies utilizing radiolabeled HDLA (d, 1.09–1.21 g/ml), HDL2, and HDL3 demonstrated rapid exchange of apoA-I and apoA-II radioactivity among HDL subfractions, similar fractional rates of catabolism
of apoA-I and apoA-II within HDL, and similar radioactivity decay within HDL subfractions. Mean plasma residence time was
5.74 days for radiolabeled HDL2 and 5.70 days for radiolabeled HDL3. Differences in HDL protein mass among individuals were largely due to alterations in catabolism, and in general both HDL2 and HDL3 were catabolized via a plasma and a nonplasma pathway. Data from simultaneous radiolabeled very low density lipoprotein and
HDL studies in 2 individuals are consistent with the concept that apoC-II and apoC-III are catabolized at a different rate
than are apoA-I and apoA-II within the HDL density range. 相似文献