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1.
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
2.
High density lipoprotein (HDL) levels are known to be higher in women than in men, and to increase with estrogen use. To assess
the effects of estrogens on HDL subspecies, analytic ultracentrifuge measurements of HDL were compared in 11 menopausal estrogen
users and 16 controls. The difference in mean schlieren patterns between the groups showed a significantly higher level of
HDL with flotation rate (F
1.20
o
)>1.5 (predominantly HDL2) in the users. This was similar to the difference in HDL seen between nonusers of hormones and age-matched males. A previous
study had shown that users of combination oral contraceptives had increased levels of HDL with F
1.20
o
≤3.5 (primarily HDL3) suggesting that the estrogen effect on HDL is altered by the presence of added progestin. The progrestin effect was studied
here in more detail in two women with type V hyperlipoproteinemia treated with norethindrone acetate. Reduction in serum triglyceride
was accompanied by a reduction in HDL, predominantly in the less dense species (HDL2). Among groups of oral contraceptive and noncontraceptive estrogen and progestin users whose HDL-cholesterol levels have
been reported recently, there was a direct correlation (r=0.86, p<.001) between mean HDL-cholesterol and triglyceride levels.
Endogenous hormonal influences on HDL were assessed by serum hormone and lipoprotein measurements at weekly intervals during
two consecutive menstrual cycles in four healthy females. An increase in HDL of highest flotation rate (F
1.20
o
5–9) was seen, which corresponded with the time of ovulation raising the possibility of pituitary as well as gonadal hormone
effects on HDL. 相似文献
3.
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
4.
Li Tian Yuye Yang Mingde Fu Yanhua Xu 《European Journal of Lipid Science and Technology》2010,112(4):502-510
Background and aims: to analyze the gender and age differences in the distribution of the high‐density lipoprotein (HDL) subclasses among the Chinese population, and to clarify the mechanism of these changes. Methods and results: the apoA‐I contents of the plasma HDL subclasses were determined by 2‐DE coupled with immunodetection in 324 men (including 186 normolipidemic subjects) and 186 women (including 114 normolipidemic subjects). The contents of preβ1‐HDL and HDL3 (HDL3c, HDL3b, HDL3a) were significantly lower, whereas the contents of HDL2a and HDL2b were higher for women than for men in the <50 years age group. Moreover, the contents of preβ1‐HDL and HDL3 were higher for female subjects; the HDL2a and HDL2b contents were lower for both female and male subjects in the 50–59, 60–69, and ≥70 years age groups versus the subjects of the same gender in the <50 years age group. When compared to the normolipidemic premenopausal women, preβ1‐HDL, HDL3b, and HDL3a increased while HDL2b decreased significantly in normolipidemic men and postmenopausal women. Conclusions: the contents of the large‐sized HDL particles HDL2b were higher, but the contents of the small‐sized HDL particles (preβ1‐HDL, HDL3b, HDL3a) were lower for women versus men in the <50 years age group. Meanwhile, the gender difference in distribution of the HDL subclass narrowed obviously with advancing age. Moreover, the characteristics of the HDL subclass distribution profile for the normolipidemic postmenopausal women resembled those for the normolipidemic men. 相似文献
5.
Li Tian Xinwei Wu Mingde Fu Yanhua Xu Lianqun Jia 《European Journal of Lipid Science and Technology》2008,110(10):879-886
Background and aims: To investigate the impact of plasma apoA‐II concentrations on the alteration of HDL subclass distribution, and the cooperative effect of apoA‐I and apoA‐II on it. Methods and results: The apoA‐I contents of plasma HDL subclasses were quantified by two‐dimensional gel electrophoresis associated with immunodetection for 292 Chinese people. These subjects were divided according to the mean ± 1 SD of apoA‐II and apoA‐I levels as two cut‐points, respectively. Compared with the low‐apoA‐II group, the apoA‐I contents of HDL3a (in the high group), HDL3b, and HDL2b increased strikingly, both in the middle‐ and high‐apoA‐II group. The apoA‐I contents of all HDL subclasses increased progressively when the apoA‐I and apoA‐II levels simultaneously or the apoA‐I/apoA‐II ratio increased, and in comparison to the low‐apoA‐I–A‐II levels group, the apoA‐I contents of HDL2b (115%) increased more significantly than those of preβ1‐HDL (39%) in the high‐apoA‐I–A‐II levels group. Multiple analyses also indicated that the three HDL subclasses, HDL3a, HDL3b and HDL2b, were independently predicted by apoA‐II. Conclusion: Excess apoA‐II can cause the accumulation of both large‐sized HDL2b and small‐sized HDL3, which implies that apoA‐II plays a double role in the HDL maturation metabolism. Meanwhile, the degree of HDL2b increased significantly relative to that of preβ1‐HDL when apoA‐I and apoA‐II levels were elevated simultaneously, suggesting that the maturation and metabolism of HDL might be promoted and reverse cholesterol transport might be enhanced. 相似文献
6.
The object of this study was to investigate the characteristics of lipid metabolism in obese subjects, with particular emphasis
on the alteration of HDL subclass contents and distributions. A population of 581 Chinese individuals was divided into four
groups (25 underweight subjects, 288 of desirable weight, 187 overweight, and 45 obese) according to body mass index (BMI).
Apoprotein A-I (apoA-I) contents of plasma HDL subclasses were determined by 2-D gel electrophoresis associated with an immunodetection
method. The concentrations of TG and the apoA-I content of pre-α1-HDL were significantly higher (P<0.01 and P<0.01, respectively), but the levels of HDL cholesterol, and the apoA-I contents of HDL2a and HDL2b were significantly lower (P<0.01, P<0.05, and P<0.01, respectively) in obese subjects than in subjects having a desirable weight. Moreover, with the elevation of BMI, small-sized
pre-α1-HDL increased gradually and significantly, whereas large-sized HDL2b decreased gradually and significantly. Meanwhile, the variations in HDL subclass distribution were more obvious with the
elevation of TG levels in obese as well as overweight subjects. In addition, Pearson correlation analysis revealed that BMI
and TG levels were positively correlated with pre-α1-HDL but negatively correlated with HDL2b. Multiple regression analysis also showed that TG concentrations were associated independently and positively with high pre-α1-HDL and independently and negatively with low HDL2b in obese and overweight subjects. The HDL particle size was smaller in obese and overweight subjects. The shift to smaller
size was more obvious with the elevation of BMI and TG, especially TG levels. These observations, in turn, indicated that
HDL maturation might be abnormal, and reverse cholesterol transport might be impaired.
The first two authors contributed equally to this study. 相似文献
7.
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
8.
The ultracentrifugal flotation patterns in 1.2 g/ml solvent and ultracentrifugal gradient distribution of high density lipoproteins
(HDL) from the primates-human, apes and monkeys-were determined, with emphasis on the gorilla species of apes and rhesus monkeys.
Diets for non-human primates were commercial chow, which is low in cholesterol. Molecular weights and protein, cholesterol,
phospholipid and triglyceride compositions of various density fractions were determined on human, gorilla and rhesus HDL.
The HDL2/HDL3 ratio was determined from the two peaks observed upon flotation in high salt in the analytical ultracentrifuge. The HDL2 of all three species of apes-gorillas (Gorilla gorilla), chimpanzees (Pan troglodytes) and orangutans (Pongo pygmaeus)—was always greater than HDL3, while that of all six species of Old World monkeys-Rhesus (Macaca mulatta), sooty mangabeys (Cercocebus atys), cynomolgus (Macaca fascicularis), stumptails, (Macaca arctoides) patas (Erythrocebus patas) and African greens (Cercopithecus aethiops)—was less. In addition, the HDL3 concentration in five gorillas was about 15 mg/dl as cholesterol while the HDL2 concentration was 92 mg/dl, much lower and higher, respectively, than humans. HDL2 of gorillas was similar in density and molecular weight to that of humans. The distribution of densities in gorilla HDL was
predominantly in HDL2, while rhesus HDL usually, but not always, was unimodal, having a density distribution similar in heterogeneity to human
HDL3, but somewhat less dense (peaking at 1.109 vs 1.129 g/ml). The molecular weight of rhesus HDL was about the same as human
HDL3 in all three density subfractions and at the peak density. Likewise, the chemical compositions were similar for the subfractions
1.10–1.125 and>1.125 g/ml for rhesus HDL and human HDL3. Consequently most but not all chow-fed rhesus HDL was very similar to human HDL3, but lighter in density.
A preliminary report of this study was given at the American Society for Biological Chemists Meeting in New Oreleans in April
1982. 相似文献
9.
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
10.
Supeenun Unchern Narumon Laohareungpanya Yupin Sanvarinda Kovit Pattanapanyasat Pansakorn Tanratana Udom Chantharaksri Nathawut Sibmooh 《Lipids》2010,45(7):627-633
Oxidative modification of low-density lipoprotein (LDL) has been reported in thalassemia, which is a consequence of oxidative
stress. However, the levels of oxidized high-density lipoprotein (HDL) in thalassemia have not been evaluated and it is unclear
whether HDL oxidation may be linked to LDL oxidation. In this study, the levels of total cholesterol, iron, protein, conjugated
diene (CD), lipid hydroperoxide (LOOH), and thiobarbituric acid reactive substances (TBARs) were determined in HDL from healthy
volunteers and patients with β-thalassemia intermedia with hemoglobin E (β-thal/Hb E). The protective activity of thalassemic
HDL on LDL oxidation was also investigated. The iron content of HDL2 and HDL3 from β-thal/HbE patients was higher while the cholesterol content was lower than those in healthy volunteers. Thalassemic
HDL2 and HDL3 had increased levels of lipid peroxidation markers i.e., conjugated diene, LOOH, and TBARs. Thalassemic HDL had lower peroxidase
activity than control HDL and was unable to protect LDL from oxidation induced by CuSO4. Our findings highlight the oxidative modification and poor protective activity of thalassemic HDL on LDL oxidation which
may contribute to cardiovascular complications in thalassemia. 相似文献
11.
E. Gerasimova N. Perova I. Ozerova V. Polessky V. Metelskaya I. Sherbakova M. Levachev S. Kulakova Yu. Nikitin T. Astakhova 《Lipids》1991,26(4):261-265
Native Chukot Peninsula residents, in contrast to Muscovites, consume a diet rich in n−3 polyunsaturated fatty acids. This
dietary peculiarity is reflected in differences in plasma lipid and apolipoprotein contents. The Chukot residents have lower
contents of total cholesterol, triglyceride, LDL (low density lipoprotein) cholesterol and apolipoprotein B, but higher HDL
(high density lipoprotein) cholesterol levels than do Muscovites. The apolipoprotein A-I levels were identical in both groups.
A higher HDL cholesterol to apolipoprotein A-I ratio was determined in the coastline Chukot residents (0.52±0.01) than in
Muscovites (0.43±0.01; p<0.01). In contrast to Muscovites, the coastline Chukot residents also had higher n−3 and lower n−6
polyunsaturated fatty acid percentages in plasma and erythrocyte lipids, and lower phosphatidylcholine and higher sphingomyelin
or phosphatidylethanolamine levels in HDL2b and HDL3. The higher HDL cholesterol levels in the plasma of the coastline Chukot residents appears to reflect the higher cholesterol-scavenging
capacity of their HDL.
We conclude from this study that the regular consumption of dietary n−3 polyunsaturated fatty acids by the coastline Chukot
residents decreased LDL cholesterol transfer from plasma to peripheral cells, and enhanced cholesterol efflux from cellular
membranes toward HDL. 相似文献
12.
Native fish-eye disease plasma, which is deficient of both high density lipoproteins (HDL) and lecithin-cholesterol acyltransferase
activity (α-LCAT), processing the free cholesterol of these lipoproteins, has been supplemented with normal isolated HDL2 or HDL3 and incubated in vitro at 37 C. After incubation for 0,7.5 and 24 hr the very low density (VLDL) and low density (LDL) lipoproteins
as well as HDL were isolated, and their contents of triglycerides, phospholipids and free, esterified and total cholesterol
were quantified. The resulting net mass transfer of the different lipids revealed a functioning transfer of cholesteryl esters
and all other analyzed lipids between the lipoproteins, although no de novo esterification of the HDL cholesterol by LCAT
in this plasma occurred. In accordance with previous findings there was a functioning esterification process of the free cholesterol
of the combined VLDL and LDL of fish-eye disease plasma. The present results make it reasonable to conclude that the lack
of HDL cholesterol esterification in this disease is not a result of a deficiency of cholesteryl ester transfer or lipid transfer
activities. 相似文献
13.
Human low density lipoproteins (LDL) were isolated and purified from individuals having widely differing serum lipid concentrations.
Very low density lipoproteins (VLDL) and high density lipoproteins (HDL) were also isolated and quantitated. HDL2 and HDL3 were separated by flotation velocity in the analytical ultracentrifuge and their relative weight percent determined. The
mean density of LDL from 41 individuals was determined by flotation velocity at two different solvent densities. The mean
density of LDL was directly proportional to the triglyceride (r=0.65) and VLDL (r=0.50) concentrations and inversely proportional
to the HDL (r=−0.55) and HDL2 (r=−0.74) concentrations (all significant at P<0.001). The mean molecular weight of LDL from 42 individuals was determined
by flotation equilibrium centrifugation. The mean molecular weight of LDL was directly proportional to the HDL (r=0.49) and
HDL2 (r=0.48) concentrations and inversely proportional to the serum triglyceride (r=−0.60) and VLDL (r=−0.48) concentrations
(all significant at P<0.005 except triglyceride—P<0.001). The molecular weight of LDL was inversely proportional to its density,
and thus inversely proportional to its protein/lipid ratio which was confirmed by composition measurements. The density and
molecular weight of LDL had no relationship to the concentration of LDL (r=0.04 and 0.03).
A preliminary report of this study was given at the American Society for Biological Chemists Meeting in St. Louis, June 1981. 相似文献
14.
Li Tian Yucheng Chen Chuanwei Li Zhi Zeng Yanhua Xu Shiyin Long Mingde Fu 《Lipids》2013,48(2):127-137
Despite the established efficacy of statin therapy, the risk of cardiovascular events remains high in many patients. We examined high-density lipoprotein (HDL) subclass distribution profiles among statin-treated coronary heart disease (CHD) patients undergoing percutaneous coronary intervention (PCI). Plasma HDL subclasses were measured in 85 patients with established CHD and quantified by two-dimensional gel electrophoresis and immunoblotting. In CHD patients with statin treatment, the mean value of total cholesterol (TC) reached the desirable level and the triacylglycerol level (TAG) was borderline high. Moreover, low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), apolipoproteinA-I, and apolipoproteinB-100 levels in these patients resembled those in normolipidemic healthy subjects. The HDL subclass did not show a normal distribution and was characterized by the lower large-sized HDL2b contents and higher contents of small-sized preβ1-HDL in CHD patients, compared to those in normolipidemic control subjects. Multiple stepwise regression analysis revealed that the severity of coronary stenosis, determined by the Gensini Score, was significantly and independently predicted by HDL2b and HDL3b. Statin therapy was effective in modifying plasma lipids levels, but not adequate as a monotherapy to normalize the HDL subclass distribution phenotype of patients with CHD undergoing PCI. The HDL subclass distribution may aid in risk stratification, especially in patients with CHD and therapeutic LDL-C and HDL-C levels. 相似文献
15.
Katsuyuki Tsuda Ken'ichi Tsutsumi Manabu Yaegashi Masahiro Miyajima Takashi Ishizone Akira Hirao Fumiaki Ishii Toyoji Kakuchi 《Polymer Bulletin》1998,40(6):651-658
Summary
The radical polymerizations of 2-, 3-, and 4-(phenylethynyl)styrenes (1a–c) and the copolymerizations of 1a–c (M1) with styrene (M2) were carried out using AIBN as the initiator in toluene at 60°C. The number-average molecular weights (M
ns) were extremely low for poly(2-phenylethynylstyrene) (2a) and poly[(phenylethynyl)styrene-co-styrene] (3a), and increased in the order of 2a, 3a << 2b, 3b < 2c, 3c. Monomer reactivity ratios were determined as r
1= 1.80 and r
2= 0.51 for 1a, r
1= 1.72 and r
2= 0.53 for 1b, and r
1= 3.17 and r
2= 0.24 for 1c. Polymers 2a–c and 3a–c underwent an exothermic reaction at elevated temperature to form organic solvent-insoluble polymers. Although the decomposition
of 2a was observed from 200°C, 2b and 2c exhibited a high heat-resistance property in both nitrogen and air atmospheres, in particular, 2b showed no significant weight loss below 450°C.
Received: 28 January 1998/Accepted: 5 March 1998 相似文献
16.
Human serum lipid and lipoprotein concentrations and compositions were compared in ten healthy middle-aged men consuming phospholipids
from egg or from soybean or triacylglycerol mixtures with fatty acid compositions similar to those of the phospholipids. All
subjects followed each of the four treatments: egg phospholipids (EP), soybean phospholipids (SP), an oil of fatty acid composition
similar to that of EP, and an oil similar in fatty acid composition to SP for six weeks with “wash-out” periods of similar
duration between treatment periods. The phospholipids, 15 g/d, and the oils, 12 g/d, which contained approximately equivalent
quantities of fatty acids were provided to the subjects in gelatin capsules and were taken before meals. Diet intake was monitored
by three-day food records. Serum lipoproteins (Lp) were separated by ultracentrifugation into very low density lipoproteins, low density lipoproteins (LDL), high density lipoproteins
(HDL)2 and HDL3. Lp fractions and whole serum were analyzed for triacylglycerols, cholesterol (CH), phospholipids (PL), and protein. HDL cholesterol
was determined in while serum. Cholesteryl esters were determined in some Lp fractions. Lipid compositions of Lp were expressed in mmol/g protein. Apoprotein B was measured in whole serum and in LDL; apoprotein A-I in whole serum and
in HDL3. In whole serum, CH and PL were significantly lower after the SP compared to EP treatment periods. CH, but not PL, was lower
after SPTG compared to EP. CH in HDL2 was significantly higher after SP compared to SPTG. Also, PL in HDL2 were significantly higher after SP compared to all other treatments and to baseline. Although human serum lipid responses
to dietary phospholipids were generally the same as responses to ingested oils of comparable fatty acid composition, the data
suggest the possibility that SP selectively increase HDL2 cholesterol and phospholipids. 相似文献
17.
Rat plasma high density lipoproteins (HDL) are comprised of two major particle size subpopulations, HDL1 (255 Å?140 Å) and HDL2 (140 Å?84 Å), in which the proportion of arachidonate in fatty acids of cholesteryl esters is greater than 50%. To determine whether decreased availability of arachidonate for cholesterol esterification would alter the distribution and/or amounts of the HDL subpopulations, we compared HDL subpopulations in EFA-deficient and control rats. To separate the effects of EFA deficiency and fat deficiency and to evaluate effects of different saturated fats, we used EFA-deficient diets that were fat-free or that contained 5% saturated fat. The control diets were the EFA-deficient diets plus 1% safflower oil. The saturated fats were hydrogenated coconut oil, hydrogenated cottonseed oil and saturated medium-chain triglycerides. All EFA-deficient diets decreased the proportion of the HDL1 subpopulation and the peak diameter of the HDL2 subpopulation. These changes appeared after quite brief EFA depletion in young rats and may be related to the increased liver cholesteryl ester concentrations typical of EFA-deficient rats. 相似文献
18.
A. N. Tsvigunov 《Glass and Ceramics》2000,57(3-4):94-97
Data of an x-ray structural study of single crystals of silicon carbide α-SiC(6H) and a new, previously unknown modification γ-SiC with a rhombic lattice are described. The rhombic-lattice parameters are
related to the parametera of the hexagonal and cubic lattices of SiC in the following way:a
r=a
h,b
r=3a
h,c
r=3a
c.
Translated from Steklo i Keramika, No. 3, pp. 19 – 22, March, 2000. 相似文献
19.
Frank T. Lindgren Gerald L. Adamson Virgie G. Shore Gary J. Nelson Perla C. Schmidt 《Lipids》1991,26(2):97-101
The effects of n−3 fatty acids on plasma lipids, lipoproteins and apoproteins have usually been studied in humans after feeding
of purified fish oil. This study describes the effect of a natural diet, containing salmon as the source of n−3 fatty acids,
on these parameters as compared to a diet very low in n−3 fatty acids. The subjects were nine normolipidemic, healthy males
who were confined to a nutrition suite for 100 days. During the first 20 days of the study the participants were given a stabilization
diet consisting of 55% carbohydrates, 15% protein, and 30% fat. The n−3 content of this diet was less than 1%, and it contained
no 20- or 22-carbon n−3 fatty acids. After the stabilization period the men were split into two groups, one group continued
on the stabilization diet while the other received the salmon diet that contained approximately 2.1 energy percent (En%) of
calories from 20- and 22-carbon n−3 fatty acids. Both diets contained equal amounts of n−6 fatty acids. This regime continued
for 40 days, then the two groups switched diets for the remainder of the study. Plasma triglycerides were lowered significantly
(p<0.01) and high density lipoprotein cholesterol (HDL-C) was significantly elevated (p<0.01) after the men consumed the salmon
diet for 40 days. The very low density lipoproteins (VLDL) were lowered, but the trend did not reach statistical significance
during the intervention period. The total plasma cholesterol, total low density lipoprotein (LDL) and the total high density
lipoprotein (HDL) levels were not influenced by the salmon diet. Within the HDL fraction, however, the larger HDL2 subfractions were significantly elevated (p<0.002), and the smaller, more dense HDL3 was lowered (p<0.002) by the salmon diet. These significant changes were detected by analytic ultracentrifugation and confirmed
by gradient gel electrophoresis. Analysis of the apolipoproteins (apo) AI, AII, B, and E, and Lp(a) indicated only significant
lowering of apoAI, consistent with the increased HDL2, which is higher in cholesterol but lower in the major HDL apolipoprotein, apoAI. Thus, the purported beneficial cardiovascular
effects of consumption of n−3 fatty acids by humans may, in part, be attributable to changes in the HDL distribution,i.e., the lowering of the more dense HDL3 and the elevation of the larger, less dense HDL2. 相似文献
20.
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