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1.
The relationships between fatty liver in dairy cows and reduced levels of plasma lipoproteins, and particularly of low density
lipoproteins (LDL), has been previously described. Since electrophoretic heterogeneity of ultracentrifugally isolated LDL
(d, 1.006–1.063 g/ml) has been found, the exact nature of this reduction in cows with fatty liver was investigated. Lipoproteins
from control and severely afflicted animals were isolated by ultracentrifugation and affinity chromatography on heparin-Sepharose
CL 6 B. Gradient gel electrophoresis of lipoproteins on 4–30% gels and an immunolocalization study of apoprotein A-I (apo
A-I) showed that control animals have two subpopulations of apo A-I-containing particles with a mean radius of 6.52 and 5.05
nm. In the fatty liver cows, the former was clearly shifted toward smaller particles. We concluded that the depressed level
and compositional modifications of LDL in severe fatty liver cows result from a decrease in the oversized apo A-I-containing
lipoproteins which can be isolated in the LDL density range. This could stem from the decreased supply of triglyceride-rich
lipoprotein surface components for the production of these lipoproteins. The modifications can be plausibly explained by a
reduced synthesis or secretion of very low density lipoproteins (VLDL) by the liver. 相似文献
2.
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
3.
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
4.
Possible interactions between glycosaminoglycans and high density lipoproteins (HDL) in plasma and follicular fluid were examined.
Total lipoproteins (d<1.21 g/ml) were obtained from plasma of five Holstein cows by ultracentrifugation and fractionated by
gel filtration. Every other fraction from the HDL peak or fractions corresponding to the base and ascending portion of the
HDL peak were composited and applied to a heparin-Sepharose affinity chromatography column. Elution profiles from both composites
showed a peak that did not bind to the column that contained HDL devoid of apolipoprotein-E as determined by sodium dodecyl
sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and silver staining and immunoblot analysis. Elution of lipoproteins
from the ascending portion of the HDL peak resulted in a second minor peak eluting at 0.35 M NaCl, which was low density lipoprotein
(LDL) contamination. Lipoproteins (d<1.21g/ml) isolated from follicular fluid obtained from small, medium or large follicles
also were subjected to heparin-Sepharose affinity chromatography. Two peaks were observed, one corresponding to the lipoprotein
that did not bind to the column, the other eluted at 0.5M NaCl and accounted for less than 2% of the protein applied. The
second peak did not contain apolipoprotein-E or LDL. Bovine follicular fluid glycosaminoglycans (GAG) were isolated and subjected
to HDL-Sepharose affinity chromatography. Less than 2% of the total GAG bound to the HDL column. Therefore, HDL in bovine
specimens did not interact appreciably with heparin or GAG isolated from follicular fluid. 相似文献
5.
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
6.
Yorkshire (lean) and Ossabaw (obese) swine ca. one year of age were used to characterize the quantity and composition of plasma
lipoproteins in animals with markedly different adiposity. While lean swine weighed more (175 vs 88 kg for obese), they had
less backfat than obese swine (2.64 vs 5.97 cm; P<0.05). Fasting plasma triacylglycerol (Tg) and cholesterol (CH) levels were
elevated in obese swine. Swine plasma lipoproteins were fractionated into very low density lipoprotein (VLDL; d<1.006), low
density lipoprotein1 (LDL1; d=1.019–1.063), low density lipoprotein2 (LDL2; d=1.063–1.09), and high density lipoprotein (HDL; d=1.09–1.21) by density ultracentrifugation. Obese VLDL-Tg, CH and protein
(Pr) were elevated more than 2-fold. VLDL from obese swine were 2-fold larger than VLDL from lean swine. No alterations in
LDL1 or LDL2 composition were observed. HDL-Tg, CH, Pr and phospholipid levels were significantly higher in obese swine. Plasma and VLDL-Tg
levels were highly correlated with backfat thickness (r=0.67 and r=0.73, respectively). These was a positive correlation between
adiposity and HDL-CH as well as VLDL-Tg and HDL-CH. These data indicate that (a) there are marked alterations in swine plasma
lipoprotein composition between lean and obese swine; (b) that swine plasma lipoprotein levels may be useful parameters in
estimating body composition; and (c) that HDL-CH is positively correlated with adiposity in swine.
Department of Dairy and Animal Science, College of Agriculture.
Nutrition Program, College of Human Development. 相似文献
7.
Hepatic synthesis of lipoproteins and apolipoproteins was investigated in male Wistar rats with severe nephrotic syndrome
induced by puromycin aminonucleoside by incubating liver slices with a mixture of14C-amino acids. Labeled lipoproteins were separated by preparative ultracentrifugation from the incubation medium after the
addition of carrier plasma. The incorporation of14C-amino acids into very low density lipoproteins (VLDL) (1.006 g/ml), low density lipoproteins (LDL) (1.006–1.063 g/ml) and
high density lipoproteins (HDL) (1.063–1.210 g/ml) was increased in nephrotic liver 6.1-, 5.7- and 5.0-fold, respectively.
The measurement of radioactivity associated to apolipoproteins isolated by SDS-PAGE documented an increased incorporation
into apolipoprotein E (apoE) of nephrotic VLDL (33.1% vs 20% of the total radioactivity incorporated into VLDL apoproteins)
and a markedly increased incorporation into apolipoprotein A-I (apoA-I) of nephrotic HDL (44.3% vs 16.3% of the total radioactivity
incorporated into HDL apoproteins). In nephrotic liver, the total incorporation of amino acids into apolipoproteins (apoVLDL+apoLDL+apoHDL)
was increased 12.6 times for apoA-I, 6.4 times for apoB, 5.0 times for apoE, 4.2 times for apoC+apoA-II and 2.5 times for
apoA-IV. We suggest that, in nephrotic liver: (a) the synthesis of VLDL, LDL and HDL is increased, and (b) the total synthesis
of apoA-I is selectively increased when compared to that of the other apolipoproteins.
Preliminary reports of this work were presented at the Annual Meeting of the European Society for the Study of the Liver (Düsseldorf,
September 13–15, 1979); at the 5th International Symposium on Atherosclerosis (Houston, November 6–9, 1979) and at the Annual
Meeting of the Italian Society for the Study of the Liver (Rome, December 14–15, 1979). 相似文献
8.
We have investigated the distribution of antithrombin-III and glucosylceramide (Glc-Cer) in human plasma, plasma lipoproteins
and lipoprotein-deficient plasma. Antithrom bin III activity was measured employing immunochemical and biological assays.
Glc-Cer was quantified by gas liquid chromatography (GLC). Whole plasma contained 145 μg antithrombin III/ml plasma, all of
which was associated with the lipoprotein-deficient plasma (d>1.25 g/ml). Whereas, most if not all the plasma GlcCer was associated
with plasma low density lipoproteins (LDL) (d-1.022–1.055 g/ml) and high density lipoproteins (HDL) (d-1.063–1.25). GlcCer
was not found in the lipoprotein-deficient plasma. We conclude that GlcCer on lipoproteins does not contribute to antithrombin
III activity. Moreover, the absence of GlcCer in lipoprotein-deficient plasma does not impair antithrombin-III activity. 相似文献
9.
Some of the component moieties of high denisty lipoproteins (HDL) were analyzed in normal subjects and in patients with hyperlipidemia.
Apoproteins A-I and A-II were quantified by radioimmunoassay, HDL cholesterol and triglycerides were assessed on heparin-MnCl2 supernates of fasting plasmas. We found that HDL is enriched in triglycerides in all forms of hyperlipidemia, while the proportion
of ApoA-II is unaltered and the proportion of ApoA-I is decreased. Thus, the composition of HDL is altered in hypertriglyceridemia.
The molecular associations of ApoA-I and ApoA-II in plasma were also examined by assaying the apoprotein contents of plasma
fractions prepared by ultracentrifugation and by gel filtration column chromatography. The ApoA-I contents of d<1.063 fraction
increased in hyperlipidemia from <0.5% to ∼2%, but the ApoA-I contents of the d>1.21 fraction remained at <12% of total in
plasmas with triglyceride levels <1500 mg/dl. d>1.21 ApoA-I rose to 23% in one plasma with a triglyceride level of >1700 mg/dl.
On column chromatography, ApoA-I eluted with the lipoproteins and also in a fraction whose molecular weight (MW) appreared
to be ∼50,000 daltons. The proportion of plasma ApoA-I which eluted in the 50,000 MW peak was positively correlated with plasma
triglyceride levels, but at triglyceride levels of <1500 mg/dl, <20% of ApoA-I was in the 50,000 MW peak. Between levels of
∼2000 and 12,000 mg/dl, the percentage “50,000 M.W. ApoA-I” was 20–25%. The ApoA-II contents of d<1.063 fractions were also
increased in hyperlipidemia, but >95% of ApoA-II was found in the HDL fractions in both normal and hyperlipidemic plasma both
by column chromatography and ultracentrifugation. Thus, the molecular association of ApoA-I appears to be altered in hyperlipidemia. 相似文献
10.
Human serum lipoproteins containing B-protein have been isolated using an immunoadsorber. Bromoacetyl cellulose was combined
with pure antibodies to low density lipoprotein (LDL) and an immunoadsorber of high capacity was obtained. With 1 g of this
immunoadsorber all LDL and very low density lipoprotein (VLDL) from 30 ml pooled human serum were adsorbed and then eluted
with glycine-HCl buffer pH 3.2 at 0 C. The isolated lipoproteins were investigated by electrophoresis, immunodiffusion and
ultracentrifugation, and found to be identical to LDL+VLDL isolated by ultracentrifugation. 相似文献
11.
Incubation of a major subfraction, HDL2b (d 1.063–1.100 g/ml), of human plasma high density lipoproteins, HDL (d 1.063–1.21 g/ml), with single-bilayer liposomes of
dimyristoylphosphatidylcholine (DMPC) resulted in uptake of DMPC by the HDL2b and dissociation of lipid-free apolipoprotein A-I (apoA-I). In the presence of excess DMPC, the dissociated apoA-I was also
incorporated with DMPC into discoidal complexes. Preliminary studies with model apoA-I-DMPC complexes indicated that they
also can interact with native HDL2b with the resultant transfer of their DMPC to HDL2b and the concomitant release of their apoA-I. After interaction of HDL2b with DMPC liposomes, the DMPC-enriched HDL2b product showed a lower hydrated density and a larger particle size than the control HDL2b. The molecular properties of the lipoprotein product suggest that stabilization of the apoA-I-depleted HDL2b probably occurred via substitution of DMPC for the apoA-I at the HDL2b surface rather than by fusion of the apoA-I-depleted HDL2b. The above interactions of HDL2b with single-bilayer liposomes and discoidal complexes indicate pathways of phospholipid transfer relevant to the possible
role of HDL in the metabolism of lipoprotein surface components in vivo. 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.
Alpha- and gamma-tocopherol levels of nine women were measured in whole serum and in serum lipoproteins separated by heparin
affinity chromatography. Alphatocopherol levels (mean±SD) in whole serum, low density plus very low density lipoproteins and
high density lipoproteins were 10.8±2.7, 6.4±1.6 and 4.6±1.4 (μg/ml), respectively. Corresponding values (μg/ml) for gamma-tocopherol
were 1.2±0.5, 0.7±0.3 and 0.6±0.2. Recoveries of serum alpha- and gamma-tocopherol from the heparin columns were 102±5% and
105±7%, respectively. Serum alpha-tocopherol was linearly correlated with components of high density lipoprotein (apolipoproteins,
high density lipoprotein cholesterol), but not with serum total lipids or indices of low density lipoprotein, even though
high density lipoprotein carried less than half of the serum alpha-tocopherol. However, serum gamma-tocopherol was highly
correlated with indices of serum lipids, such as serum cholesterol (r=0.92, p=0.005). The coefficient for the correlation
of low density lipoprotein (+very low density lipoprotein) tocopherol with high density lipoprotein tocopherol was r=0.66
(p=0.06) for alpha-tocopherol and r=0.84 (p=0.004) for gamma-tocopherol. These differences in the relationships of the two
tocopherols to lipids and lipoproteins support the view that when the two tocopherols are present at normal dietary levels,
gamma-tocopherol partitions between lipoproteins based on their relative lipid content, but a portion of the alpha-tocopherol
in high density lipoprotein is specifically bound. 相似文献
14.
The interaction of human plasma high density lipoprotein HDL2 (d 1.063–1.125 g/ml) with sonicated dispersions of synthetic saturated phosphatidylcholines, dipalmitoyl- (diC16PC), dimyristoyl- (diC14PC), didodecanoyl- (diC12PC), didecanoyl- (diC10PC), and dioctanoyl- (diC8PC) L-alpha phosphatidylcholine, was investigated. Incubation (4.5 hr, 37 C) of HDL2 with diC14PC, diC12PC, diC10PC and diC8PC followed by gradient gel electrophoresis or preparative ultracentrifugation resulted in a redistribution of apolipoprotein
A-I (apoA-I). The extent of redistribution depended on the molar ratio of the phospholipid to HDL2 in the incubation mixture. Redistributed apoA-I occurred as lipid-free apoA-I and/or as complexes of apoA-I with phosphatidylcholine.
Increasing the length of time of ultracentrifugation of the interaction mixtures did not increase the extent of redistribution.
No redistribution of apoA-I was detected following incubation and gradient gel electrophoresis or preparative ultracentrifugation
of mixtures of HDL2 with dispersions of diC16PC.
Presented in part at the Joint Meeting of the American Oil Chemists' Society and the Japan Oil Chemists' Society, 1979. 相似文献
15.
Isabel S. Chen Truc Le Satchithanandam Subramanian Marie M. Cassidy Alan J. Sheppard George V. Vahouny 《Lipids》1987,22(5):318-321
Rat mesenteric lymph chylomicrons containing triglycerides enriched with either [14C]oleic acid (OA) or [14C]-eicosapentaenoic acid (EPA) were prepared by ultracentrifugation of lymph samples collected for 6 hr after a single duodenal
infusion of an emulsion containing either fatty acid. These chylomicrons were injected into the jugular vein of recipient
rats and, at various time intervals, blood was drawn and serum was assayed for radioactivity. In separate animals, serum lipoprotein
fractions were separated by ultracentrifugation, and the redistribution of labeled fatty acid among circulating lipoproteins
was determined by liquid scintillation spectrometry. When the early disappearance rates (10 min) of either total serum radioactivity
or specifically the chylomicron fraction were compared, there were no differences between the groups receiving OA-or EPA-enriched
chylomicrons. However, disappearance rates of EPA-enriched chylomicrons were slower than those of OA-enriched chylomicrons
from 25 to 90 min. The small but significant differences in the disappearance rates for the longer time periods cannot be
ascertained without further studies. At 5 min after injection of either type of chylomicron, the d<1.006 g/ml lipoprotein
fraction of serum chylomicrons and very low density lipoproteins contained almost 90% of the original radioactivity. By 240
min, when less than 2% of the radioactivity remained, this radioactivity in the d<1.006 g/ml fraction was 43–46%, with concomitant
increases in the low and high density lipoprotein fractions and in the lipoprotein-free serum.
Deceased. 相似文献
16.
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
17.
Subfractionation of the total low density Sf 4–105, the low density Sf 4–20 and high density plasma (or serum) lipoproteins has been accomplished using a cumulative flotation rate procedure. Fractionation
employs nonlinear salt gradients and high performance swinging bucket rotors. Subfractionation of the total low density lipoproteins
with minimal contamination allows and extremely accurate lipoprotein mass measurement of Sf > 400, total very low density lipoproteins and low density lipoproteins (LDL) by elemented CHN analysis. Physical and chemical
data on LDL and high density lipoprotein (HDL) subfractions are in general agreement with earlier data. Lower molecular weight
data are obtained for HDL subfractions than reported earlier; however this may be the result of the different fractionation
procedures used.
Presented in part at AOCS Meeting, New Orleans, April 1970. 相似文献
18.
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
19.
This study reports on the plasma lipid compositions of sheep fed either a control diet (C), a control diet supplemented with
tallow (A) or polyunsaturated fatty acid (B) that had been protected against hydrolysis and hydrogenation in the rumen, or
a control diet supplemented with maize oil (D). Diet B considerably increased the 18∶2 content of all the major plasma lipid
fractions. Although the feeding of diet D also resulted in an increase in the 18∶2 contents within the cholesteryl ester,
unesterified fatty acid, and phospholipid fractions the increases were considerably less than those observed with diet B;
the levels of 18∶2 within the triglyceride fraction remained similar to that for the sheep which received the control diet.
The effect of feeding diet A was confined solely to the triglyceride fraction where the concentrations of 16∶0 and 18∶1 were
increased. The lipoproteins of the plasma were separated into very low density lipoproteins (d<1.006), low density lipoproteins
(1.006<d<1.063), and high density lipoproteins (1.063<d<1.21), and the distribution of the major lipids between these lipoprotein
fractions was investigated. Diet B increased considerably the proportion of triglyceride found in association with the very
low density fraction and the concentrations of 18∶2 within all the lipoprotein fractions; these increases in the concentrations
of 18∶2 were not confined to any particular lipid fraction of the lipoproteins. In contrast, the increases in the concentrations
of 18∶2 produced as a result of feeding diet D were confined to the low and high density lipoproteins. The effect of feeding
diet A was confined to fatty acid changes within the triglycerides of the low and very low density lipoproteins. 相似文献
20.
Lavage from normal adult rabbit lung and two known derived fractions, Fraction T and Fraction S, were subjected to either
differential ultracentrifugation in 1.090 g/ml KBr or sucrose density gradient ultracentrifugation; the surface activity of
the lipid extract of selected fractions was measured. In differential ultracentrifugation, the three starting materials yielded
a pellicle containing > 85% of the phospholipid with <1% protein. In sucrose density gradient ultracentrifugation: pulmonary
washing, containing about equal weights of phospholipid and protein (60% albumin, 20% sIgA, 10% IgG, 10% minor proteins),
produced one single band at density 1.040, containing virtually one single protein, namely >80% of the total sIgA (protein
T) and up to 60% of the total phospholipid, whereas all the albumin and IgG were found at very low densities, 1.010 and 1.025,
respectively; Fraction T, having nearly equal weights of one signle protein, sIgA, and phospholipid, produced two contiguous
bands at densities 1.059 and 1.078, totalling >85% of its phospholipid and <25% of its protein, the balance of which was found
free of phospholipid at densities 1.020 to 1.050; comprising >80% of the phospholipid and <20% of the protein of pulmonary
washing, Fraction S yielded two small bands at densities 1.028 and 1.044 and a major band at d=1.059. In surface activity
measurements: when the total lipid extract of the bands from the sucrose density gradient ultracentrifugation was spread as
a film, in spite of similarly high dipalmitoyl lecithin contents (about 70% palmitoyl lecithin contents (about 70% palmitoyl
residue), the lipid of the band of Fraction T and that of the high density band of Fraction S were very active (γ
min=0); whereas the lipid of the band of pulmonary washing and that of the lowest density band of Fraction S were not active,γ
min being 18 dyne/cm and 21 dyne/cm, respectively. This wokk brings forth three major conclusions. First, under conditions which
are used to isolate serum lipoproteins, no lipoprotein was obtained from either of the three surfactant fractions and most
of the lipid was found virtually free of protein. Second, the isopicnic equilibrium of a given ultracentrifugation fraction
varied with the molecular structure of its constituents and could not be accounted for by the latter’s average densities;
instead, major roles must be player by particle geometry and their water contents. Third, although the various lipid samples
contained the same quantities of palmitoyl residues (70%), the surface activities varied with the physical state of the lipid,
method of assay, and some other undefined factors. 相似文献