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1.
The incorporation of L-4,5-[3H]leucine into the ultracentrifugally separated apolipoproteins of very low, low, and high density lipoproteins (VLDL, LDL,
HDL) and into serum albumin was found three-to four-fold higher in nephrotic than in normal rats one hour after intravenous
injection. Incorporation of leucine into the circulating lipids was negligible. Increases of similar magnitude were obtained
in the incorporation of simultaneously injected 1,5[14C] citrate into the lipids of VLDL, LDL, and HDL of nephrotic rats. Of the citrate carbons incorporated into serum and liver
lipids, the proportion in cholesterol was higher in nephrotic rats when compared to normal rats. The incorporation of both
precursors into total proteins and lipids of the liver vs. the incorporation into the lipoproteins was relatively lower in
nephrotic than in control rats, indicating a preferential channeling into secretable products. The occurrence of enhanced
new lipid synthesis in nephrosis was corroborated by the finding of markedly enhanced synthesis of lipoprotein-borne fatty
acids and cholesterol from3H2O. These results point out that while leucine is not an efficient in vivo precursor of lipoprotein lipids in nephrosis, de
novo lipogenesis proceeds from other precursors. Similar trend of changes, though of smaller magnitude, was elicited in rats
after double plasmapheresis, 18 hr apart, when measured 3 hr after the second plasma withdrawal. This indicates that the loss
of circulating proteins either by direct removal or through kidney lesion stimulates the compensatory hepatic response involving
excessive lipoprotein synthesis. Time-course studies showed that peak incorporation of leucine and citrate into the protein
and lipid components of lipoproteins, respectively, as well as into serum albumin, occurred coincidentally 3 hr after the
second plasmapheresis, suggesting an interdependence of the enhanced protein and lipid synthesis. 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.
The effect of protein depletion in the pregnant rat on the polyunsaturated fatty acid incorporation into very low density
lipoproteins (VLDL) has been investigated. The apoprotein pattern of these particles was determined. In in vivo experiments
the amounts of serum and liver triacylglycerol were determined. VLDL were isolated and their apo C concentration calculated.
In in vitro experiments the radioactivity of [3H] leucine incorporated into VLDL apoproteins was measured. The results show that protein depletion during pregnancy promotes
a drastic increase in serum and liver triacylglycerol. The VLDL isolated from these animals show an increase in the triacylglycerol/protein
ratio and a decrease in their content of apo C. Meanwhile, a significant reduction in the [3H]leucine incorporation into apo C peptides by the perfused liver of protein depleted rats was detected. On the other hand,
protein deprivation did not affect labeled linoleic and arachidonic acid incorporation into triacylglycerol of the newly secreted
VLDL. Taking these results together, let us deduce that a defective VLDL is secreted by the liver of the protein depleted
pregnant rats. The abnormal composition of these particles may influence its normal metabolism through their effects on lipoprotein
lipase and this fact could affect the normal supply of polyunsaturated fatty acids to the fetus. 相似文献
4.
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
5.
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
6.
Livers from rats with experimental hypoproteinemia induced by aminonucleoside-nephrosis or plasmapheresis were perfused with
a [14C]-labeled amino acid mixture at physiological concentration. Compared to control rats, a significantly increased incorporation
of the amino acid label was found in the apolipoproteins of the ultracentrifugally separated very low and high density lipoproteins
(VLDL, HDL), and into albumin secreted into the perfusate. However, no increase in the amino acid-derived label was detected
in VLDL- or HDL-borne lipids in nephrosis or plasmapheresis. Perfusion with U-[14C] leucine as a lipogenesis precursor at >10 times higher than physiological concentration resulted in 5-fold increase in
the label incorporation into perfusate proteins in nephrosis but only in a slightly significant increase in perfusate lipids.
In contrast, the incorporation of a preformed fatty acid, 9,10-[3H] oleate into VLDL and HDL lipids increased 3- to 4-fold in nephrosis. Both with leucine and oleate as precursors, the increments
in the label appearing in perfusate proteins or lipids, respectively, were markedly greater than the increases in hepatic
tissue proteins or lipids. The results indicate that amino acids are preferentially directed by the liver into the synthesis
of circulating apolipoproteins and albumin in hypoproteinemia and do not seem to constitute an important precursor of the
lipoprotein lipids. The increased production of apolipoproteins is associated with an increased incorporation of preformed
fatty acids into lipoprotein lipids in addition to the previously reported stimulation of hepatic de novo lipid synthesis
from precursors other than amino acids. 相似文献
7.
Serum cholesterol precursor sterols reflect the activity of cholesterol synthesis. In this study, squalene, methyl sterol
and lathosterol contents were studied in very low density lipoprotein (VLDL), low density lipoprotein (LDL) and high density
lipoprotein (HDL) of heterozygous familial hypercholesterolemia patients without and with ileal bypass. The contents of lathosterol
and all methyl sterols (lanosterol, Δ8,24-dimethylsterol, Δ8-dimetylsterol, Δ8-methostenol and methostenol), but not of squalene were increased in all lipoproteins by ileal bypass. The increase in the
free methyl sterols was more marked than that in the esterified ones. The percentage esterification of the methyl sterols
was highest in HDL and lowest in VLDL. Lipoprotein methyl sterol contents were positively correlated with each other and with
cholesterol synthesis. The methyl sterols were slightly concentrated in LDL, and squalene strongly concentrated in VLDL. It
is concluded that long-term stimulation of cholesterol synthesis increases the methyl sterols in all lipoproteins. 相似文献
8.
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
9.
Human aortic smooth muscle cells (SMC) specifically bind and take up indiscriminately both the lipid and protein moietics
of homologous25I-very low density lipoproteins (VLDL) and125I-low density lipoproteins LDL). Sixty-five to 80% of absorbed lipids are incorporated into the cell lipids, preferentially
into the phospholipid fraction. Twenty to 35% of the lipid bound and the protein moiety are eliminated from the cells. Half
of the eliminated protein label is recovered as TCA soluble products. Five mM of p-chlorophenoxyisobutyrate (CPIB) raise the
level of intracellular radioactivity derived from the lipid moieties of VLDL and LDL by about 40% via a reduced elimination.
The processing of the protein moiety and lipoprotein binding to the cell surface are not affected by 5.0 mM of CPIB. CPIB
lowers the incorporation of14C-acetate,14C-pyruvate, and32phosphate radioactivity into fatty acids and phospholipids of aortic SMC. Five mM of CPIB reduce the overall palmitic acid
synthesis by shifting from de novo synthesis to the mechanism of chain elongation, although the further elongation to saturated
C18–C24 fatty acids is also depressed. The CPIB-enhanced retention of the lipid-derived lipoprotein radio-activity is interpreted
as a compensatory mechanism providing cellular fatty acids which are deficient as a result of the CPIB inhibited synthetic
processes. 相似文献
10.
Free cholesterol of plasma low density lipoproteins (LDL) and high density lipoproteins (HDL) of the rat was high and that
of plasma very low density lipoproteins (VLDL) was low during the dark period of the diurnal cycle. Variations in the esterified
plasma sterols were inconsistent. Free methyl sterols were high in all lipoproteins during the dark phase. Simultaneously,
the incorporation of14C-acetate into nonsaponifiable sterols and the concentrations of free methyl sterols and cholesterol in the liver were elevated. 相似文献
11.
High performance liquid chromatography with gel exclusion columns was used for quantitative measurement of plasma lipoproteins.
A combination of columns TKS 4000 PW and 3000 PW gave good separation of very low (VLDL), low (LDL) and high (HDL) density
lipoproteins. The area under each lipoprotein peak detected by absorbance at 280 nm was measured by digitizing and was expressed
as cm2. Purified lipoprotein standards isolated by ultracentrifugation were also chromatographed in increasing concentrations. The
area under the lipoprotein standard peak was linearly related to the amount of total protein over a wide range. The areas
of most of the measured plasma lipoproteins were within the linear range. The relationship between the area and the amount
of protein for each standard was used to quantitate the amount of protein and was expressed as mg/dl plasma. This technique
is simple and requires a small amount of plasma. The validated technique was applied to a large population of pedigreed baboons.
An average plasma lipoprotein profile of feral baboons on the chow diet was characterized by a high level of HDL (90.9±30.7
mg/dl) with a lesser amount of LDL (29.1±13.2 mg/dl). VLDL was present in much lower concentration (8.6±2.6 mg/dl). Feeding
a high cholesterol and high saturated fat (HCHF) diet raised both LDL (1.5-fold) and HDL levels (1.3-fold) without changing
VLDL levels. Progeny of sires with low response to dietary cholesterol increased their HDL protein when challenged with HCHF
diet without any change in their LDL or VLDL. Progeny of high-responding sires, however, had increases in both their HDL and
LDL levels when challenged with HCHF diet. The survey of lipoprotein profiles of the pedigreed baboon colony disclosed a number
of animals with interesting and unusual lipoprotein patterns. 相似文献
12.
The isolated perfused rat lung was used as an experimental model in the study of the lipoprotein regulation of surfactant
cholesterol metabolism. Addition of low density lipoproteins (LDL) to the perfusion medium at a cholesterol concentration
of 0.5 mM had no inhibitory effect on [1-14C]-acetate incorporation into cholesterol of either the surfactant or residual fractions. Increasing the concentration of
cholesterol in the medium to 2.5 mM resulted in significant inhibition of incorporation into cholesterol of both fractions.
A similar inhibition resulted when lungs were perfused with 2.5 mM cholesterol in the form of high density lipoproteins (HDL).
No inhibition of fatty acid synthesis, measured as incorporation into cholesteryl esters, was observed. The rate of uptake
by perfused lung of cholesterol from both high and low density lipoproteins was similar. Competitive binding studies with125I-labeled lipoproteins indicated the existence of lung receptors for both classes of lipoprotein. The rate of uptake of the
apoprotein moiety of low density lipoproteins was significantly greater than that of high density lipoproteins. These data
suggest that lung cholesterol metabolism may be subject to regulation by both low and high density serum lipoproteins. 相似文献
13.
Elyett Gueux Christine Cubizolles Laurence Bussière Andrzej Mazur Yves Rayssiguier 《Lipids》1993,28(6):573-575
Hypertriglyceridemia observed in magnesium (Mg)-deficient rats was associated with a significant increase in the very low-density
lipoprotein (VLDL) plus low-density lipoprotein (LDL) fractions. The results fromin vitro copper-induced lipid peroxidation, expressed in terms of conjugated dienes and thiobarbituric acid reactive substances content,
showed that VLDL+LDL particles from Mg-deficient rats were more susceptible to oxidative damage than lipoproteins from control
rats. These results suggest that the mechanism responsible for the atherogenicity and tissue damage characteristic of Mg deficiency
may be mediated by an increased susceptibllity of triglyceride-rich lipoproteins to peroxidation in hypertriglyceridemic animals. 相似文献
14.
Pe¯teris Alberts Gunnel Klingstrm Vibeke Arrhenius‐Nyberg Catarina Larsson Kjell S. Sakariassen 《European Journal of Lipid Science and Technology》2006,108(6):453-458
The aim of the present study was to assess cholesterol‐containing lipoprotein profiles in minute serum samples. The lipoprotein profiles of KKAy and transgenic KKAy‐CETP mice and of other species were determined. The transgenic KKAy‐CETP mice express the simian enzyme cholesteryl ester transfer protein (CETP). The serum profile of the cholesterol‐containing high‐density (HDL), low‐density (LDL) and very‐low‐density lipoproteins (VLDL) was monitored on a Superose 6 column using fast protein liquid chromatography. Serum from several mouse and rat strains, rabbit, hamster, pig and man was included for comparative and method validation purposes. The chromatograms showed that the transgenic KKAy‐CETP mice had significantly decreased relative levels of HDL vs. VLDL and LDL cholesterol (p <0.001). Introduction of the CETP gene shifted the serum profile of the cholesterol‐containing lipoproteins of the KKAy‐CETP mice closer to the human profile in a dose‐dependent manner, thus making these mice an interesting model for man. The described lipoprotein separation technology offers promising and reliable opportunities for studies of blood lipoprotein profiles with minute serum samples, in both animals and man. 相似文献
15.
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
16.
Gazi IF Apostolou FA Liberopoulos EN Filippatos TD Tellis CC Elisaf MS Tselepis AD 《Lipids》2011,46(10):953-960
The objective of the present study was to evaluate the effects of acute infection with Leptospira interrogans on lipids, lipoproteins and associated enzymes. Fasting serum levels of total cholesterol (TC), low-density lipoprotein cholesterol
(LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), apolipoproteins (apo) A-Ι, B, E, C-II, C-III and
lipoprotein (a) [Lp(a)] were determined in patients with Leptospirosis on diagnosis and 4 months after recovery as well as
in age- and sex-matched controls. Activities of cholesteryl-ester transfer protein (CETP) and lipoprotein-associated phospholipase
A2 (Lp-PLA2) as well as paraoxonase 1 (PON1) hydrolysing activity and levels of cytokines were determined. LDL subclass analysis was
performed with Lipoprint LDL System. Eleven patients (10 men, mean age 49.5 ± 8.4 years) and 11 controls were included. TC,
HDL-C, LDL-C, apoA-I, apoB and Lp(a) levels were lower at baseline, whereas TG and apoE levels were elevated compared with
4 months later. At baseline, higher levels of cytokines and cholesterol concentration of small dense LDL particles (sdLDL-C)
were noticed, whereas LDL particle size was lower compared with follow-up. Activities of plasma Lp-PLA2 and HDL-associated Lp-PLA2 were lower at baseline compared with post treatment values, whereas PON1 activity was similar at baseline and 4 months later.
4 months after recovery, the levels of all lipid parameters evaluated did not differ compared with controls, except for HDL-C
which remained lower. PON1 activity both at baseline and 4 months later was lower in patients compared with controls. Leptospirosis
is associated with atherogenic changes of lipids, lipoproteins and associated enzymes. 相似文献
17.
Maria Luz Fernandez A. Karin Conde Laura R. Ruiz Carlos Montano John Ebner Donald J. McNamara 《Lipids》1995,30(7):619-626
To test the effects of exchanging dietary complex and simple carbohydrate for fat calories on lipoprotein metabolism, guinea
pigs were fed two different fat/carbohydrate ratios: 2.5∶58% (w/w) or 25∶29% (w/w) with either sucrose or starch as the carbohydrate
source. Animals fed high-fat had higher plasma low-density lipoprotein (LDL) and hepatic cholesterol concentrations than animals
fed low-fat diets (P<0.01). The cholesteryl ester content per particle was higher, and the number of triacylglycerol (TAG) molecules was lower
in very low density lipoprotein (VLDL) and LDL from animals fed high-fat diets. Intake of high-fat/sucrose resulted in higher
plasma LDL concentrations than intake of high-fat/starch, and animals fed low-fat/starch had the highest plasma TAG concentrations
associated with VLDL particles containing more TAG molecules, as well as a TAG-enriched LDL. The activity of plasma lecithin
cholesteryl:acyl transferase (LCAT) was highest in animals fed high-fat/sucrose, and heart lipoprotein lipase (LPL) activity
was higher in animals fed high-fat diets. Hepatic apoprotein B/E (apo B/E) receptor number (Bmax) was increased 21% with low-fat diets (P<0.01). These results suggest that the hypercholesterolemia induced by high-fat and by sucrose intake are associated with
a higher plasma LCAT activity which results in a cholesteryl ester-enriched VLDL which, by the action of LPL, might be more
readily converted to LDL through the delipidation cascade leading to downregulation of hepatic apo B/E receptors. The hypertriglyceridemia
associated with low-fat intake may result from increased production of VLDL TAG, which would explain the increased TAG content
and the higher TAG/CE ratio of VLDL from animals fed the low-fat/starch diet. 相似文献
18.
Raul C. Maranhão Thais B. Cesar Suzana R. Pedroso-Mariani Mario H. Hirata Carlos H. Mesquita 《Lipids》1993,28(8):691-696
A protein-free microemulsion (LDE) with a lipid composition resembling that of low-density lipoprotein (LDL) was used in metabolic
studies in rats to compare LDE with the native lipoprotein. LDE labeled with radioactive lipids was injected into the bloodstream
of male Wistar rats, and plasma kinetics of the labeled lipids were followed on plasma samples collected at regular intervals
for 12 h after injection. The 24-h LDE uptake by different tissues was also measured in tissue samples excised after the animals
had been sacrificed. We found that LDE plasma kinetics were similar to those described for native LDL [fractional clearance
rate (FCR) of cholesteryl ester, 0.42±0.11 h−1]. The major site for LDE uptake was the liver, and the tissue distribution of the LDE injected radioactivity was as one would
expect for LDL. To test whether LDE was taken up by the specific LDL receptors, the LDE emulsion was injected into rats treated
with 17α-ethinylestradiol, which is known to increase the activity of these receptors; as expected, removal of LDE from the
bloodstream increased (FCR=0.90±0.35 h−1). On the other hand, saturation of the receptors that remove remnants by prior infusion of massive amounts of lymph chylomicrons
did not change LDE plasma kinetics. These results indicate that LDE is cleared from plasma by B,E receptors and not by the
E receptors that remove remnants. Incorporation of free cholesterol into LDE increased LDE plasma clearance. Incubation studies
also showed that LDE incorporates a variety of apolipoproteins, including apo E, a ligand for recognition of lipoproteins
by specific receptors. Our data suggest that LDE can be a useful tool to test LDL metabolism and B,E receptor function. 相似文献
19.
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
20.
Apolipoprotein E allele 4 (apo ɛ4) and smoking each have been associated with an unfavorable lipid profile. We used data collected on 1,472 subjects in the
National Heart, Lung, and Blood Institute Family Heart Study to assess whether smoking interacts with apo ɛ4 to influence the levels of plasma lipids. We dichotomized smoking and apo ɛ4 and used analysis of covariance to estimate the means of lipids. Smokers had lower body mass index, were younger, and consumed
less fruits and vegetables. Among individuals without apo ɛ4, comparing nonsmokers with smokers, mean low density lipoprotein cholesterol (LDL) was 129.3 and 134.4 mg/dL, respectively,
for women and 126.1 and 127.6 mg/dL, respectively, for men. Among subjects with an apo ɛ4 allele, corresponding means were 132.0, and 152.9 mg/dL, respectively, for women and 131.3 and 137.3 mg/dL, respectively,
for men (P for interaction <0.001 for women and 0.11 for men). A similar interaction was observed for total cholesterol among women
(P=0.02). This study shows a statistically significant effect modification of the relation of apo ɛ4 to LDL and total cholesterol by smoking among women. Smoking may enhance genetic susceptibility to an unfavorable lipid profile
among subjects with apo ɛ4. 相似文献