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1.
The influence of different fat diets on liver phospholipid, cholesterol and dolichol was studied. Rats were separated into
four groups and fed standard laboratory chow (control), a diet containing linolenic acid, a coconut oil diet, or a corn oil-containing
diet. After five weeks, microsomes and mitochondrial/lysosomal fractions were prepared from the liver, and lipid compositions
were analyzed. No changes in phospholipid content were observed. In control animals, the fatty acid compositions of phosphatidylcholine
and phosphatidylethanolamine in the two subfractions were similar. However, these two phospholipids showed different fatty
acid patterns, which were altered independently upon dietary treatment. The dietary treatments resulted, in most cases, in
decreased cholesterol and dolichol contents and, especially in microsomes, in a decreased level of esterification of both
lipids. The fatty acid compositions of cholesteryl esters in the two subfractions showed significant differences and cholesterol
was esterified to a large extent with linolenic acid when this fatty acid was supplied in the diet. The same dietary treatment
exerted different effects on the cholesterol localized in the two different intracellular compartments. This difference was
most pronounced in rats fed the corn oil-containing diet; microsomal cholesteryl esters exhibited increased saturation, whereas
cholesteryl esters in the mitochondrial/lysosomal fraction displayed decreased saturation. Dolichyl esters in the two cellular
compartments had different fatty acyl compositions, with a considerably higher degree of saturation in microsomes. The various
diets influenced the nature of the fatty acid moieties present in the isolated fractions and the effects on the two subfractions
were opposite. The diet containing linolenic acid decreased the degree of saturation in microsomal dolichyl esters and increased
the degree of saturation in the mitochondrial/lysosomal fraction. The results demonstrate that the fatty acid compositions
of both dolichyl and cholesteryl esters display organelle specificity. Both the content of these lipids and their fatty acid
compositions are greatly influenced by dietary conditions, and the esterification processes at different cellular locations
exhibit independent regulation, regardless of the fatty acid content of the diet. 相似文献
2.
The levels of cholesterol, ubiquinone, dolichol, dolichyl-P, and total phospholipids in human lung, heart, spleen, liver,
kidney, pancreas, and adrenal from individuals from one-day-old to 81 years of age were investigated and compared with the
corresponding organs from 2 to 300 day-old rats. The amount of cholesterol in human tissues did not change significantly during
aging, but the level of this lipid in the rat was moderately elevated in the organs of the oldest animals. In human pancreas
and adrenal the ubiquinone content was highest at one year of age, whereas in other organs the corresponding peak value was
at 20 years of age, and was followed by a continuous decrease upon further aging. A similar pattern was observed in the rats,
with the highest concentration of ubiquinone being observed at 30 days of age. Dolichol levels in human tissues increase with
aging, but they increase to very different extents. In the lungs this increase is seven-fold, and in the pancreas it is 150-fold.
The elevation in the dolichol contents of rat tissues ranges from 20 to 30-fold in our material. In contrast, the levels of
the phosphorylated derivative of dolichol increased to a more limited extent, i.e., 2 to 6-fold in human tissues and even
less in the rat. These results demonstrate that the levels of a number of lipids in human and rat organs are modified in a
characteristic manner during the life-span. This is in contrast to phospholipids, which constitute the bulk of the cellular
lipid mass. 相似文献
3.
Stig Ekman 《Lipids》1987,22(9):657-663
A new technique for preparing microemulsion particles of well-defined sizes and compositions is presented. Utilization of
these microemulsions is advocated as lipoprotein models in studies of lipid transport and metabolism, rather than the currently
used phospholipid-cholesterol vesicles. The emulsion particles consisted of egg phosphatidylcholine and cholesterol as surface
lipids and cholesteryl oleate as core lipid. They were prepared by a combined injection and sonication technique and size-separated
by a two-step procedure of gel filtration chromatography and density gradient centrifugation. By varying the ratios of core
and surface material, particles covering a size range of 20–200 nm in diameter could be produced. The adequacy of these microemulsions
as lipoprotein models was tested by studying the transfer of [3H]cholesterol and [14C]cholesterol oleate from the particles to cultured human fibroblasts. Up to a particle size of 100 nm, there was a slight
increase of [3H]cholesterol transfer. The transfer of [14C]cholesteryl oleate was very slow, yet measurable. Studies of the exchangeability of cholesterol between the microemulsion
core and surface phases indicated that all cholesterol can be transferred from microemulsions to cultured cells as a single
pool. 相似文献
4.
An effective system for perfusing rat liver using complete tissue culture medium and washed calf erythrocytes as oxygen carriers
was devised. Infusion of taurocholate and glucose proved necessary to maintain stable metabolic activity an bile secretion
during a 6-hr period. Perfusate pO2, pCO2 and pH values were monitored continuously and found to be stable. Electron microscopic examination revealed the maintenance
of normal hepatic structure, even after 6 hr. Normal rates of protein and urea synthesis, no leakage of cytoplasmic enzymes,
and continuous bile acid production demonstrated the functional integrity of this system. Using [3H]mevalonic acid as precursor, dolichol, dolichyl phosphate, ubiquinone and cholesterol were found to be continuously synthesized
in this perfusate, indicating discharge through the ER-Golgi system. The lipoproteins of the perfusate were isolated by ultracentrifugation
and characterized with respect to size distribution and lipid composition. Dolichol was found in VLDL, LDL and HDL fractions,
with the highest concentration present in the latter. In rat and human blood plasma this lipid was mainly associated with
HDL. The ubiquinone in the perfusate was primarily associated with the VLDL fraction, while in rat plasma it was found more
evenly distributed among all the three lipoprotein fractions studied. Dolichol, ubiquinone and cholesterol were also discharged
to the bile, whereas dolichyl phosphate was not. Thus, newly-synthesized dolichol and ubiquinone are transported out of the
hepatocyte to the blood and to the bile. 相似文献
5.
Isolated rat hepatocytes were preincubated with egg lecithin liposomes containing [3H]dolichol and [3H]-dolichyl ester, and the intracellular levels and distributions of these lipids were subsequently determined after incubation
in a liposome-free medium. [3H]Dolichol was recovered initially mainly in microsomes, and no increase with time in the low level of this compound in the
mitochondrial/lysosomal fraction could be observed. A small portion of the labeled dolichol was esterified in the endoplasmic
reticulum and transferred to the lysosomecontaining fraction. [3H]Dolichyl linoleate was initially localized in microsomes and supernatant, but later accumulated in the mitochondria/lysosomes.
Dolichyl linoleate was found in the membrane of microsomes, in the membrane and lumen of lysosomes, and in the soluble cytoplasm.
Exogenous dolichol recovered in microsomes was not phosphorylated to any significant extent. Liposomal phosphatidylcholine
also showed preferential accumulation in microsomes after incubation with hepatocytes. These results indicate that exogenous
or endogenously formed dolichyl esters are transferred from the endoplasmic reticulum to lysosomes, probably through the cytoplasm.
It appears that fatty acids play a role in targeting these lipids to their intracellular locations. 相似文献
6.
Rat intestinal lymph very low density lipoproteins have been separated by cellulose acetate electrophoresis. After administration
of a meal including natural fats and labeled fatty acids, two labeled bands were detected on the electrophoregraphs. Further
separations of these two kinds of particles were performed by density gradient zonal centrifugation. The isolated lipoproteins
were analyzed for chemical composition and investigated by electron microscopy and electrophoresis. The moving particles had
a higher protein and cholesterol content and a smaller diameter than the particles which remained at the origin. It has also
been shown that the major part of the labeled lymph lipids were transported by the smaller particles. 相似文献
7.
Ehrlich ascites cells were grown in mice and were isolated by centrifugation of the ascites fluid. The cells were lysed with
distilled water, and the floating fat particles were collected by centrifugation. The particles contained about 90% neutral
and 10% polar lipid. The neutral lipid was made up of about 50% triacylglycerol, 30% alkyldiacylglycerol, 3% cholesteryl esters,
3% free cholesterol and 4% free diacylglycerols. The phospholipid fraction was comprised of about 50% phosphatidylcholine,
35% phosphatidylethanolamine, 10% sphingomyelin and small amounts (less than 5% total) of serine and/or inositol phosphatides.
The triacylglycerol and alkyldiacylglycerol fractions possessed total carbon number and fatty acid compositions closely similar
to these reported in the literature for whole ascites cells and for a cell membrane preparation. Likewise, the fatty acid
composition of phospholipids from the granules in general was similar to that reported for Ehrlich ascites cells. On the basis
of the polar and neutral lipid ratio, the lipid granules of the ascites cells were calculated to possess lipid core diameters
of 30–50 nm, which were 40–70 times smaller than those (up to 2μ) measured for the lipid granules of the intact cells by electron
microscopy. The characterization of the lipid composition of the Ehrlich ascites lipid granules was completed by determing
the molecular species composition of the diacyl, alkylacyl and alkenylacyl phosphatidylethanolamines and of the diacyl and
alkylacyl phosphatidylcholines of the ascites cells. It is concluded that the alkyldiacylglycerols of the Ehrlich ascites
cells occur largely in the cytoplasmic lipid granules, which appear to consist of many particles of the size and structure
of very low density lipoproteins enclosed in membranous sacs. 相似文献
8.
Extraction and quantitation of total cholesterol,dolichol and dolichyl phosphate from mammalian liver 总被引:2,自引:0,他引:2
A procedure is described for the determination of total cholesterol, dolichol and dolichyl phosphate (Dol-P) in mammalian
liver. It is based on extraction of these compounds into diethyl ether after alkaline saponification of the tissue. Extractability
is affected by the length of saponification and concentration of potassium hydroxide (KOH) in the saponification mixture.
After extraction, total cholesterol and dolichol are quantitated directly by reverse-phase high pressure liquid chromatography
(HPLC) on C18. Dol-P requires further purification before quantitation by HPLC, this is accomplished by chromatography on silicic acid.
These methods gave recoveries of over 90% for cholesterol and dolichol and about 60% for Dol-P, using [4-14C]cholesterol, a polyprenol containing 15 isoprene units, and [1-14C]Dol-P as recovery standards. Concentrations of total cholesterol, dolichol and Dol-P in livers from one month-old-CBA mice
were found to be 5.7±0.7 mg/g, 66.3±1.2 μg/g and 3.7±0.3 μg/g, respectively. 相似文献
9.
A rapid and simple method capable of purifying surfactant from rabbit alveolar washings and from washings contaminated with
serum has been developed. The sample, containing 16% NaBr, is placed beneath a two-layer discontinuous gradient of NaBr. After
centrifugation, the surfactant is found near the top of the gradient tube at a density of 1.085 at 4 C while the contaminating
material remains near the bottom. The lipid composition of surfactant from lung washings of normal animals isolated by this
method compares quite favorably with surfactant isolated by much more elaborate and time consuming methods. Surfactant purified
from mixtures of3H-palmitate labeled rabbit serum and lung washings (1.6 mg serum phospholipid: 1 mg washing phospholipid) contained less than
3% of the phospholipid radioactivity. The phospholipid composition of this band was quite similar to that of surfactant from
normal lung washings, but the protein content was much higher. A second density gradient centrifugation removed 90% of this
protein resulting in a surfactant fraction with a phospholipid to protein ratio similar to that of surfactant from normal
lung washings. These findings demonstrate that this purification method is capable of removing a large proportion of both
serum phospholipids and proteins from lung washings contaminated with serum, making this method uniquely suitable for evaluation
of surfactant in pathologic conditions of the lung. 相似文献
10.
Balboa E Morales G Aylwin P Carrasco G Amigo L Castro J Rigotti A Zanlungo S 《Lipids》2012,47(1):13-25
Niemann-Pick C2 protein (NPC2) is a lysosomal soluble protein that is highly expressed in the liver; it binds to cholesterol
and is involved in intracellular cholesterol trafficking, allowing the exit of lysosomal cholesterol obtained via the lipoprotein
endocytic pathway. Thus, this protein may play an important role in controlling hepatic cholesterol transport and metabolism.
The aim of this work was to study the relevance of NPC2 protein expression in hepatic cholesterol metabolism, biliary lipid
secretion and gallstone formation by comparing NPC2 hypomorph [NPC2 (h/h)] and wild-type mice fed control, 2% cholesterol,
and lithogenic diets. NPC2 (h/h) mice exhibited resistance to a diet-induced increase in plasma cholesterol levels. When consuming
the chow diet, we observed increased biliary cholesterol and phospholipid secretions in NPC2 (h/h) mice. When fed the 2% cholesterol
diet, NPC2 (h/h) mice exhibited low and high gallbladder bile cholesterol and phospholipid concentrations, respectively. NPC2
(h/h) mice fed with the lithogenic diet showed reduced biliary cholesterol secretion, gallbladder bile cholesterol saturation,
and cholesterol crystal and gallstone formation. This work indicates that hepatic NPC2 expression is an important factor in
the regulation of diet-derived cholesterol metabolism and disposal as well as in diet-induced cholesterol gallstone formation
in mice. 相似文献
11.
Richard C. Crain 《Lipids》1982,17(12):935-943
A protein that accelerates transfer of phospholipids of varying head group and fatty acid composition has been purified from
bovine liver. As previously found for other phospholipid transfer proteins, “nonspecific lipid transfer protein” stimulates
a kinetically biphasic transfer of radioactively labeled phospholipid from small unilamellar vesicles to unlabeled multilamellar
vesicles. The kinetics are consistent with rapid transfer of phospholipid from the outer monalyer and slow transfer of that
localized in the inner monolayer (half-times greater than 3 days for phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol).
Protein catalyzed transfer is inhibited by high ionic strength and has an activation energy of 35 kJ/mol. The broad lipid
specificity and ease of large-scale purification make these proteins candidates for membrane phospholipid compositional modification.
The compositions of rat liver mitochondrial and microsomal membranes and Morris hepatoma 7288c mitochondrial membranes were
altered by incubation with lipid vesicles and nonspecific lipid transfer protein. Incubation with phosphatidylcholine vesicles
led to increased levels of phosphatidylcholine and decreased levels of other transferrable lipids (phosphatidylethanolamine,
phosphatidylinositol, and cholesterol) unless the latter were included in the vesicles. When vesicles containing dipalmitoylphosphatidylcholine
were incubated with microsomal membranes, a large increase in disaturated phosphatidylcholine was also observed. These changes
in composition were correlated with activities of membrane enzymes. It appears that microsomal glucose-6-phosphatase is inhibited
by increased phosphatidylcholine saturation. Moreover, this enzyme is also inhibited by decreases in the phosphatidylethanolamine/phosphatidylcholine
ratio whereas NADPH cytochrome c reductase is not. Likewise, decreased cholesterol to phospholipid ratios did not greatly
affect the abnormally low levels of hepatoma succinate cytochrome c reductase activity.
This paper was presented at the 73rd AOCS annual meeting, Toronto, Canada, May 1982. 相似文献
12.
Removal of lipid from intact erythrocytes and ghosts by aqueous solutions and its relevance to membrane structure 总被引:2,自引:0,他引:2
Molar values for cholesterol, total phospholipid, and individual phospholipid classes of intact erythrocytes and their membranes
(ghosts) washed with various aqueous solutions are presented. The data show that lipid can be washed from erythrocyte ghosts
prepared rapidly from freshly drawn blood but that lipid is not removed from intact erythrocytes under the same conditions.
Thus, it appears that the polar groups of lipids of intact cells are not exposed as they are in ghosts. In the preparation
of hemoglobin-free ghosts, up to 25% cholesterol and phospholipid can be removed, while loss of ca. 50% cholesterol and phospholipid
from ghosts can be achieved with aqueous solutions containing ethylenediamine tetraacetate. No significant loss of membrane
protein was encountered even when almost half of the lipid had been removed from the ghosts. Phospholipid classes were removed
to different extents with different wash solutions. Lipid loss from ghosts can be prevented, in part, by adding 0.5% albumin
or calcium to wash solutions containing ethylenediamine tetraacetate. These findings contrast a report where insignificant
lipid loss was noted in the preparation of hemoglobin-free human erythrocyte membranes, but agree with results reported for
bovine red cell ghosts. 相似文献
13.
Isolation and chemical composition of surface-active material from human lung lavage 总被引:1,自引:0,他引:1
Surface-active material (SF) was isolated from human lung lavage fluid collected at autopsy employing differential and sucrose
density gradient centrifugation. The isolated material showed well-defined electron microscopic structure, consisting of clearly
preserved, closely packed vesicles with limiting membranes and inclusion bodies. It showed a very high degree of alkaline
phosphatase specific activity and was devoid of other subcellular contaminants. The isolated material also showed a high phospholipid/protein
ratio and increasing surface activity when monitored at different stages of purification. It contained 68.5% phosphatidylcholine,
11.5% phosphatidylglycerol and relatively smaller amounts of phosphatidylethanolamine and other individual phospholipid (PL)
classes. In addition, cholesterol, unesterified fatty acids, triacylglycerols and other neutral lipids were found. Saturated
fatty acids, particularly palmitic acid (16∶0), predominated in the major PL fractions. However, various fatty acids of which
oleic acid (18∶1) constituted a large proportion also are present. Chemical analysis of the material showed that besides lipids
and proteins, nucleic acids, sialic acid, hexose, amino sugars, nitrogen and phosphorus were present. The delipidated material
showed the presence of three to four proteins as characterized by sodium dodecylsulfate (SDS)-polyacrylamide gel electrophoresis,
and gel permeation chromatography on Sephadex G-200 resolved two well-separated peaks. The first fraction contained serum-associated
68 kDa protein, while the second fraction had two apoproteins with molecular weights of 34 kDa and 10 kDa. These two proteins
were associated with the SF and they, as well as the whole surface-active material, strongly reacted with the antibody directed
against the whole SF in a double-diffusion immunoprecipitation assay. The first Sephadex fraction containing a 68 kDa protein
did not produce any precipitation line when reacted against antisera. 相似文献
14.
Thoracic lymph was collected from 13 dogs fed corn oil and butterfat. The chylomicrons were isolated by centrifugation. The
lipid composition of the fat core and the membrane of the chylomicron was compared to that of the surrounding lymph serum.
The fat cores contained 90–96% triglyceride, 0.7–1.9% free cholesterol, 0.2–0.5% steryl ester, 0.9–3.5% free fatty acid and
1.4–6.1% diglyceride, but no phospholipid. The lipids of the membranes contained 58–75% phospholipid, 20–35% triglyceride,
2–5% free cholesterol, 1–2% free fatty acid, and 2–3% diglyceride, but little or no steryl ester. The membrane phospholipids
were made up of 70–90% lecithin, 5–20% phosphatidyl ethanolamine, and 1–3% each of lysolecithin and sphingomyelin. The lymph
serum contained 24–47% of total lipid as phospholipid, of which 70–92% was lecithin; the phosphatidyl ethanolamine, lysolecithin
and sphingomyelin also present contributed 1–10% each. The neutral lipids of the lymph serum contained 49–75% triglyceride,
2–15% free cholesterol, 6–23% esterified cholesterol, 10–33% free fatty acid and 1–6% diglyceride.
Alterations in dietary fat, or plant sterol supplementation led to lesser changes in the lipids of the chylomicron membranes
than in the lipids of any other lymph fraction. The least variation was seen in the phospholipids.
Taken in part from a PhD Thesis submitted by T. C. Huang to Queen's University, Kingston, Canada, in April 1965. Presented
at the AOCS 56th Spring Meeting, Houston, May 1965. 相似文献
15.
Mevalonate 5-pyrophosphate decarboxylase was studied in isolated enterocytes obtained from duodenal, jejunal and ileal villi
and crypts. In our assay conditions, decarboxylase activity was linear for 60 min and up to 0.3 mg of protein. The subcellular
location of decarboxylase in chick enterocytes was investigated. About 94% of the total activity was recovered in the cytosol.
The distribution of enzyme activity in epithelial cells also was studied. Maximal specific activity was found in cell fractions
from jejunum followed by ileum and duodenum. About 80% of total activity was recovered in the villus cells, indicating an
active role of these cells in cholesterogenesis. Ileal cells showed the highest cholesterol content. In all the intestinal
epithelial cells assayed, free cholesterol represented about 95% of the total cholesterol. 相似文献
16.
The uptake of dolichol and cholesterol by perfused rat liver was studied. When these radioactive lipids were incorporated
into egg phosphatidylcholine liposomes, both dolichol and cholesterol appeared initially in the supernatant and in the microsomal
fraction and, later on, in the mitochondrial-lysosomal fraction. The lipids taken up were esterified to some extent, but no
phosphorylation of dolichol occurred. Incorporation of dolichol and cholesterol into lipoproteins increased the efficiency
of uptake, which was receptor-mediated in this case. Accumulation of these lipids occurred in lysosomes followed by a transport
to the endoplasmic reticulum (ER). Both labeled dolichol and cholesterol appeared in the bile. In the case of dolichol, the
majority of this radioactivity was not associated with the original substance itself, and probably represented lipid-soluble
catabolites. In the case of cholesterol, most of the radioactivity was associated with bile acids. It appears that, in contrast
to the receptor-mediated uptake of lipoproteins from the perfusate, the uptake of liposomal lipids involves a different mechanism.
After association with the plasma membrane, the lipids enter into the cytoplasm and are transported to the ER and later to
the lysosomes. 相似文献
17.
Haikal Z Play B Landrier JF Giraud A Ghiringhelli O Lairon D Jourdheuil-Rahmani D 《Lipids》2008,43(5):401-408
In the human intestinal content after a meal, cholesterol is dispersed in a complex mixture of emulsified droplets, vesicles, mixed micelles and precipitated material. The aim of this study was to determine the contribution of the main intestinal cholesterol transporters (NPC1L1, SR-BI) to the absorption processes, using different cholesterol-solubilizing donors. Cholesterol donors prepared with different taurocholate concentrations were added to an apical medium of differentiated TC7/Caco-2 cells. As the taurocholate concentrations increased, cholesterol donor size decreased (from 712 to 7 nm in diameter), which enhanced cholesterol absorption in a dose-dependent manner (38-fold). Two transport processes were observed: (1) absorption from large donors exhibited low-capacity transport with no noticeable transporter contribution; (2) efficient cholesterol absorption occurs from small lipid donors (相似文献
18.
Henk F. J. Hendriks Pieter J. A. M. Brekelmans Rien Buytenhek Adriaan Brouwer A. Margreet de Leeuw Dick L. Knook 《Lipids》1987,22(4):266-273
The neutral lipid and phospholipid compositions of purified sinusoidal (fat-storing, endothelial and Kupffer) cells, parenchymal
cells and liver homogenates were determined by thin layer chromatography. In addition, the retinoid content of the same purified
cell populations was determined by high performance liquid chromatography. From each cell type, both a lipid droplet fraction
and a pellet fraction (containing the majority of the remaining cell organelles) were prepared by differential centrifugation.
Electron microscopic analysis showed that lipid droplets isolated from fat-storing cells were larger (up to 8 μm) than those
isolated from parenchymal cells (up to 2.5 μm). Moreover, the parenchymal lipid droplets seemed to be surrounded by a membranous
structure, while the fat-storing lipid droplets seemed not to be. Both fat-storing and parenchymal cells contained high concentrations
of neutral lipids, 57.9 μg and 71.0 μg/106 cells, respectively, while endothelial and Kupffer cells contained only 8.6 μg and 13.8 μg/106 cells of neutral lipids, respectively. Sixty-five percent of fat-storing cell lipid droplet fractions comprised esters of
retinol and cholesterol. This combined ester fraction contained mainly retinyl esters. In addition, considerable quantities
(20%) of triglycerides were present. Parenchymal cell lipid droplet fractions comprised triglycerides (62%) and cholesteryl
esters (up to 30%). The pellet fractions prepared from all four cell types consisted mainly of cholesterol (41–67%) and free
fatt acids (20–28%). The phospholipid content was much higher in parenchymal cells than in the sinusoidal liver cell types.
The relative proportions of the four major phospholipid classes were comparable in all liver cell types analyzed. It is concluded
that parenchymal cell lipid droplets comprised mainly triglycerides and cholesteryl esters, which is in agreement with the
function of parenchymal cells in lipid metabolism. Fat-storing cell lipid droplets consisted of retinyl esters and triglycerides,
which correlates well with their function in retionid storage and metabolism. 相似文献
19.
目的分离人尿液中的exosomes,并对其超微形态学和免疫特性进行鉴定。方法以超速离心法分离健康志愿者混合尿液中的exosomes,通过负染电镜和免疫电镜技术对exosomes进行鉴定,运用1-D SDS-PAGE对其蛋白质组分进行分离。结果 4℃,17 000×g离心15 min后的上清液于4℃,200 000×g离心1 h可得到纯度较高的exosomes。负染电镜可见exosomes为扁平或球形小体,直径主要在60 nm左右;免疫电镜显示,黑色胶体金颗粒均匀分布在exosomes球形体表面,因其具有很高的电子密度而呈现为清晰可辨的黑点;1-D SDS-PAGE分析显示,exosomes高丰度条带主要分布于相对分子质量90 000~110 000之间,且出现了数条清晰的、相对分子质量在30 000~60 000之间的条带,小于30 000的条带明显减弱。结论已建立了从人尿液中分离exosomes的方法,为进一步研究潜在的疾病相关生物标志物奠定了基础。 相似文献
20.
Gabriella Cavallini Antonella Sgarbossa Ilaria Parentini Ranieri Bizzarri Alessio Donati Francesco Lenci Ettore Bergamini 《Lipids》2016,51(4):477-486
Dolichol, an end product of the mevalonate pathway, has been proposed as a biomarker of aging, but its biological role, not to mention its catabolism, has not been fully understood. UV‐B radiation was used to induce oxidative stress in isolated rat hepatocytes by the collagenase method. Effects on dolichol, phospholipid‐bound polyunsaturated fatty acids (PL‐PUFA) and known lipid soluble antioxidants [coenzyme Q (CoQ) and α‐tocopherol] were studied. The increase in oxidative stress was detected by a probe sensitive to reactive oxygen species (ROS). Peroxidation of lipids was assessed by measuring the release of thiobarbituric acid reactive substances (TBARS). Dolichol, CoQ, and α‐tocopherol were assessed by high‐pressure liquid chromatography (HPLC), PL‐PUFA by gas–liquid chromatography (GC). UV‐B radiation caused an immediate increase in ROS as well as lipid peroxidation and a simultaneous decrease in the levels of dolichol and lipid soluble antioxidants. Decrease in dolichol paralleled changes in CoQ levels and was smaller to that in α‐tocopherol. The addition of mevinolin, a competitive inhibitor of the enzyme 3‐hydroxy‐3‐methylglutaryl CoA reductase (HMG‐CoAR), magnified the loss of dolichol and was associated with an increase in TBARS production. Changes in PL‐PUFA were minor. These findings highlight that oxidative stress has very early and similar effects on dolichol and lipid soluble antioxidants. Lower levels of dolichol are associated with enhanced peroxidation of lipids, which suggest that dolichol may have a protective role in the antioxidant machinery of cell membranes and perhaps be a key to understanding some adverse effects of statin therapy. 相似文献