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1.
After in vitro incubation of rat epididymal fat pads with radioactive palmitic acid, the distribution of the label in the
different lipid classes and in different triglycerides was determined by silica gel and silver nitrate-silica gel thin-layer
chromatography (TLC).
The radioactivity of the diglycerides was approximately half of the triglycerides. This ratio did not change with alteration
in the time of incubation. It remained unaltered even after a subsequent 10-min incubation in a nonradioactive medium.
When the fat pads were incubated, first with14C-, then with3H-labeled palmitic acid, the3H/14C ratio was slightly lower in diglycerides than in triglycerides.
The fully saturated molecules contained 38% of the radioactivity of triglycerides. Addition of oleic acid or norepinephrine
to the labeled palmitic acid-containing medium decreased this value. Subsequent incubation with these compounds did not alter
the distribution of radioactivity. 相似文献
2.
In an attempt to correlate the incorporation of fatty acids (FA) of different chain length into liver and biliary lipids’
isolated rat livers were perfused for 2 h with Krebs-Ringer bicarbonate containing 1% albumin and 10 μmol of [1-14C]-labeled FA: C2’ C8’ C10’ C12’ C16’ and C18∶1. One to 1.36 μmol of medium-chain fatty acids (MCFA’ C8’ C10’ and C12) and 6.6 μmol of long-chain FA (LCFA) were incorporated into liver lipids’ 40% of the latter into phosphatidylcholine (PC).
14C-acetate (13 nmol) was incorporated into biliary cholesterol; 14C-MCFA contributed only 3.2–5 nmol; LCFA did not lead to newly synthesized cholesterol. Newly synthesized liver PC (2.75 to
3.25%) and newly synthesized liver cholesterol (6.5 to 10%) were secreted into bile. The specific radioactivity of biliary
PC after infusion of all-saturated FA was 3.8–6.8 times higher than that of liver PC; for C18∶1 it was only 1.7-fold. The specific radioactivity of biliary cholesterol’ as compared to liver cholesterol’ was 12 times higher
for C2 and five times higher for MCFA. This indicates that a considerable proportion of the newly synthesized lipids was secreted
into bile prior to significant mixing with preexisting liver PC and cholesterol pools. liver PC contained 8% of unchanged
14C−C12; while 14C−C10 was not detected. Biliary PC’ in contrast’ contained 18% of unchanged 14C−C12 and 3% 14C−C10. These results suggest that after prolonged infusion of medium-chain triacylglycerols/longchain triacylglycerols to patients’
biliary PC may become enriched with MCFA. In addition’ the oxidation of these FA may provide C-2 units which increase cholesterol
synthesis. 相似文献
3.
The fatty acid compositions at the 1-, 2-, and 3-positions3 of rat liver triglycerides were determined by using pancreatic lipase and diglyceride kinase. The distribution of acids between
the 1- and 3-positions is not random; rather each position has a characteristic composition. The relative abundance of species
and positional isomers in the triglyceride mixture was predicted by using values from the stereospecific analysis and assuming
that the composition of each position is independent of the other two. The total triglyceride was resolved into species by
using TLC with silver nitrate and Silica Gel G, and the relative amounts corresponded closely with those predicted on the
basis of this assumption.
The major species were isolated, and the distribution of their fatty acids among the three glyceride positions was determined.
From these data the relative amount of each positional isomer was calculated. The results indicate that the esterification
of fatty acids at each position proceeds with a specificity that is not correlated with the composition of the other positions
with the molecule.
The relative abundance of the different liver triglyceride species is also found to be related in part to the composition
of the 1,2-diglyceride units found in the lecithins of this tissue.
Presented at the AOCS Meeting, Philadelphia, October 1966. 相似文献
4.
Rats intravenously administered (14C) 2-aminoethylphosphonic acid (AEP) incorporated ca. 16% of the total injected compound into liver lipids. Thin layer chromatography
and selective chemical and enzymatic hydrolysis of the labeled lipids demonstrated that essentially all of the radioactivity
was in one compound, diacylglycerol-AEP, the phosphonate analog of phosphatidylethanolamine. Lipids from kidneys, heart, skeletal
muscle, adipose, pancreas and brain were examined and found to contain less than 2% collectively of the total injected radioactivity.
The residues from the tissues contained ca. 3.2% of the total injected (14C) AEP. 相似文献
5.
Fat-deficient rats were fed different amounts of methyl linoleate for increasing periods of time. The fatty acid composition
of triglycerides and phospholipids of epididymal fat pad, epirenal fat depot, intestinal fat depot, liver, and the pool of
heart, kidney, lungs and pancreas was determined. The distribution of the total amount of linoleic and arachidonic acid incorporated
into phospholipids and triglycerides per rat was calculated. Phospholipids and triglycerides of depot tissues presented different
fatty acid compositions.
Although the phospholipids of liver and the pool of heart, kidney, lung and pancreas specifically incorporated linoleic acid
at the beginning they very rapidly attained a rather steady composition, whereas triglycerides went on incorporating the acid.
The amount of linoleic acid incorporated into the phospholipids of depot tissues was rather small. The triglycerides undoubtedly
contributed in the highest proportion to the total pool of linoleic acid. However, the highest proportion of arachidonic acid
was found in the total pool of phospholipids.
The total amount of linoleic acid incorporated into the phospholipids was an approximately lineal function of the amount of
phospholipids independent of period of administration and doses of methyl linoleate. Besides presenting two lineal functions
of the amount of phospholipids, arachidonic acid showed a vertical increase coincident with a vertical decrease of the amount
of eicosa-5,8,11-trienoic acid. At this period no change in the amount of the phospholipid was shown. This phenomenon is explaioned
as a possible direct replacement of eicosatrienoic acid by arachidonic acid. 相似文献
6.
3-Methylindole (3MI) is the causative agent in the development of acute bovine pulmonary edema. Microscopic studies revealed
a structural disruption in the lamellar bodies of type II cells, indicating an abnormal metabolism of phospholipid in the
lung of 3MI treated animals. In the present study, lung slices from 4 goats were used to investigate the changes in phosphatidylcholine
metabolism induced by 3MI. Eighteen slices were cut from each healthy lung and divided into control and 3MI groups. After
a 4-hr pretreatment with 3MI (.19 or .57 mM) or carrier, the level of incorporation of14C-choline into phosphatidylcholine, sphingomyelin and their water soluble intermediates was studied. The uptake of14C-choline and its incorporation into phosphatidylcholine and sphingomyelin was depressed by 3MI treatment. In the water soluble
fractions, the radioactivity increased in free choline and CDP-choline while it decreased in P-choline. This suggests that
choline kinase and the P-choline transferases have become relatively more rate limiting and may play a role in the depressed
de novo synthesis of phosphatidylcholine induced by 3MI. 相似文献
7.
The maize triglycerides were resolved into species by silver nitrate thin layer chromatography. The distribution of the fatty
acids among the 1, 2 and 3 positions of each triglyceride species was determined by stereospecific analysis. From these data
the relative amounts of each positional isomer were calculated. The results indicate that esterification of the fatty acids
at each position proceeds with a specificity that is correlated with the composition of the other positions of the triglyceride. 相似文献
8.
M. K. Chang E. J. Conkerton D. Chapital P. J. Wan 《Journal of the American Oil Chemists' Society》1994,71(10):1173-1175
The behavior of conjugated fatty acid triglycerides and diglycerides on reverse-phase chromatography was studied. Trieleostearin
is a geometric isomer of trilinolenin. The conjugated double bond arrangement in trieleostearin enhances its hydrophobic interaction
with the stationary phase and causes it to be eluted later than trilinolenin. In separation of “critical pairs” of tri- and
diglycerides, diglycerides elute later than triglycerides due to the longer fatty acid constituent. Position isomers of 1,2-
and 1,3-diglycerides can be separated by reverse-phase high-performance liquid chromatography. 相似文献
9.
Enzymatic enrichment of conjugated linoleic acid isomers and incorporation into triglycerides 总被引:3,自引:0,他引:3
Gerald P. McNeill Chris Rawlins Anne C. Peilow 《Journal of the American Oil Chemists' Society》1999,76(11):1265-1268
A method was developed for the enrichment of either the cis9,trans11 or the trans10,cis12 isomer of conjugated linoleic acid (CLA) from a synthetic CLA mixture consisting predominantly of these isomers in equal
amounts. Lipases were screened for their ability to selectively esterify one isomer at a significantly greater rate than the
other isomer. An immobilized lipase from Rhizomucor miehei was nonselective, but a lipase from Geotrichum candidum esterified the cis9,trans11 isomer more rapidly than the trans10,cis12 isomer. This selectivity was exploited at the kilogram scale to prepare an ester fraction with a content of 91% cis9,trans11 CLA and an unreacted free fatty acid fraction consisting of 82% trans10,cis12 CLA, based on total CLA content. The components of the reaction mixture were separated by molecular distillation. Each
enriched fraction was then incorporated into palm oil triglycerides by interesterification with the non-selective lipase from
R. miehei. Two triglyceride fats resulted, which were enriched in either cis9,trans11 CLA (26.5% cis9,trans11 and 1.7% trans10,cis12) or trans10,cis12 CLA (3.5% cis9,trans11 and 22.9% trans10,cis12). 相似文献
10.
Intratracheal administration of the anticancer drug bleomycin to hamsters produced an increase in the uptake and incorporation
of [14C] choline into phospholipids of lung slicesin vitro. The stimulatory effect is opposite to the results obtained previously using [14C] acetate and would appear to occur distal to cytidine diphosphocholine. Although alternate explanations are possible, the
results are consistent with morphological evidence, published by others, indicating an increase in lung phospholipid following
bleomycin treatment, and illustrate the significance of precursor selection when evaluating the effects of xenobiotics on
phospholipid synthesis. 相似文献
11.
Separation of monoglycerides,diglycerides, and triglycerides by liquid-liquid extraction 总被引:1,自引:0,他引:1
Summary Ternary-equilibrium data were obtained at 60°C. for mono- and dilaurin, and di- and trilaurin with aqueous alcohols. Distribution
between phases and solvent selectivity are shown graphically. Variation of solvent polarity by water addition caused a shift
in the phase boundary curve so that either Type 1 or Type 2 diagrams could be obtained.
Pure mono-, di-, and trilaurin mixtures, and commercial monoglycerides were studied as quaternary systems for monoglyceride
distribution with 50 wt.-% aqueous ethanol. Pure and commercial systems showed similar distribution tendencies even with differences
in molecular weight and degree of unsaturation.
Solvent selectivity data (β) for quaternary systems were predicted from ternary systems studied with a common solvent.
Aqueous ethanol will separate mixtures of mono-, di-, and triglycerides by selective liquid-liquid extraction; however the
literature favors more complex systems based on two immiscible solvents.
Continuous countercurrent extraction of commercial monoglycerides by 40% aqueous ethanol solution in a four-stage agitated
column gave a 15% over-all stage efficiency. Cooling the extract to 0°C. precipitated 96.6% of the extract solids.
Flow diagrams were prepared for batch and continuous extraction processes.
The findings reported in this paper were included in a thesis submitted by J. A. Monick to the Graduate Division of the College
of Engineering of New York University in partial fulfillment of the requirements for the degree of Doctor of Engineering Science.
Presented at the fall meeting, American Oil Chemists’ Society, in Philadelphia. Pa., October 10–12, 1955. 相似文献
12.
The incorporation of the dietarycis 18∶1 (n−12) andcis 18∶1 (n−10) into liver mitochondrial membrane phospholipids and adipose tissue trigly cerides was studied in 4 groups of
rats fed diets containing 10 weight percent (wt%) of fat with the following contents of octadecenoic acids: 50%cis 18∶1(n−12) +9%cis 18∶1 (n−9); 25%cis 18∶1 (n−12)+32%cis 18∶1 (n−9); 50%cis 18∶1 (n−10)+10%cis 18∶1 (n−9); or 54%cis 18∶1 (n−9). Dietary linoleic acid was 3 wt% in all 4 groups. In the mitochondrial membranes, the isomeric octadecenoic acids
were primarily incorporated into the 1-position of phosphatidylcholines and phosphatidylethanolamines at the expense of saturated
fatty acids. The maximal incorporations observed in the 1-position of phosphatidylethanolamines were 4.8% 18∶1 (n−12) and
8.9% 18∶1 (n−10). No effects on the contents of polyunsaturated fatty acids in the phospholipids were seen. In the adipose
tissue, the isomeric octadecenoic acids were incorporated at a level of 13%cis 18∶1 (n−12) or 23%cis 18∶1 (n−10), paralleled by a reduction in the content of oleic acid.
Presented in part at the 9th Scandinavian Symposium on Lipids, Visby, Sweden, June 1977. 相似文献
13.
Preincubation of rat brain and liver slices in a medium (5% glucose, 5% fructose, 1% albumin, 1% trypsin, 10 mM phosphate buffer pH 6.0) used to pretreat brain tissue for the separation of cell types was found to uncouple the incorporation of (1-14C) acetate into ethanolamine phosphoglycerides from that of the choline phosphoglycerides. Incorporation into ethanolamine phosphoglycerides was stimulated in both brain (330%) and liver (780%) slices, while the incorporation of (1-14C) acetate into choline phosphoglycerides was reduced for both brain (71%) and liver (63%) slices, compared to control values from nonpreincubated material. With (1-14C) linolenic acid as a precursor, no significant differences were found in incorporation into ethanolamine phosphoglycerides and choline phosphoglycerides. 相似文献
14.
After intracerebral injection of C14-ethanolamine into rats, the ethanolamine phosphoglycerides were isolated and hydrolyzed with mild alkali and acid. The specific
radioactivity of the diacyl, acyl alkenyl, and acyl alkyl glyceryl-3-phosphorylethanolamine, the diacyl and acyl alkenyl glyceryl-3-phosphorylcholine,
and sphingomyelin was determined at 0.5, 2, 24, and 48 hours. The specific radioactivity-time relationships show that the
ethanolamine plasmalogen is not a precursor for the glyceryl ether form but suggest that acyl alkyl glyceryl-3-phosphorylethanolamine
is desaturated to form some of the acyl alkenyl glyceryl-3-phosphorylethanolamine. The radioactivity in the choline portion
of the choline phospholipids was very low.
Presented at the AOCS Meeting, Cincinnati, October 1965. 相似文献
15.
The incorporation of 1-14C-linoleic acid, 1-14C-α-linolenic acid and 1-14C-arachidonic acid into rat liver lipids was measured and the per cent distribution of radioactivity into the different lipid
fractions determined. Normal rats were injected into the portal vein with the labeled solutions during a one minute period.
Livers were quickly frozen, pulverized, and the lipids extracted and fractioned by thin layer chromatography. No significant
differences were observed in the amounts of labeled fatty acids incorporated per gram of rat liver. While 1-14C-linoleic acid and 1-14C-α-linolenic acid were found in appreciable amounts in the 1,2 diacylglycerol fraction, about one fifth as much 1-14C-arachidonic acid was esterified in this fraction. 1-14C-arachidonic acid was the leading acid esterified in the phospholipid fractions. 相似文献
16.
The uptake by hamster intestinal rings of labeled 1,3-diolein and triolein in bile salt emulsions was studied.
About 6% of triolein was taken up from emulsions containing glycerides and fatty acid in 6 mM sodium taurodeoxycholate. Lesser
uptake was noted when triolein was emulsified with lecithin, cholesterol and bile salt; lowest uptake (3%) was observed from
triolein-lecithincholesterol emulsions prepared without bile salt.
Absorption of 1,3-diolein from bile salt emulsion was greater and acylation to triglyceride was observed.
Diglycerides and triglycerides in small quantity may be absorbed intact from a micellar phase. 相似文献
17.
The incorporation of 1,2-14C-ethanolamine into the liver phosphatidylethanolamines (PE) and phosphatidylcholines (PC) in female rats was studied. These
phosphatides were fractionated according to their degrees of unsaturation and the specific activities of monoenoic, dienoic,
tetraenoic and hexaenoic fractions were measured at intervals of 1, 20, 60 and 300 min after injection of the labeled precursor.
Hexaenoic and dienoic PE incorporated and lost the label rapidly. Although the labeled precursor was incorporated into tetraene
PE at a similar rate, this fraction attained a relatively low specific activity that remained essentially constant between
10 and 300 min after injection of the label. Hexaenoic PC had the highest specific activity among the PC fractions at all
time periods. Estimations of the rate of loss of radioactivity in the hexaenoic PE fraction and its appearance in hexaenoic
PC indicate that the docosahexaenoic acid is conserved, possibly by being reincorporated into PE after becoming a part of
the hexaenoic PC species. The high rate of turnover of the hexaenoic PE also suggests that this fraction might have some special
role in endogenous choline synthesis. 相似文献
18.
We have used the isolated perfused lung (IPL) preparation from the rat to determine whether uptake of choline from the vascular
compartment could limit the rate of synthesis of phosphatidylcholine (PC). The uptake of choline was rapid and did not saturate
at a concentration of 10 mM. The rate of incorporation of choline into phospholipid was saturated above 0.1 mM choline. Whereas,
uptake and incorporation were depressed at 4 C, uptake was neither dependent on the extracellular sodium concentration nor
inhibited by equimolar concentrations of hemicholinium-3 (HC-3). We could find no evidence that uptake might limit synthesis
of lung lecithin and conclude that uptake is either by free diffusion, or by a carrier-mediated process with a very high Km. 相似文献
19.
The effect of saturated and unsaturated fats on in vitro formation and release of lipids and cholesterol from14C acetate by rat intestinal tissue was investigated. The rats were fed a basal diet enriched with either 25% corn oil or lard
and then sacrificed after a 10- or 25-day feeding period. It was observed that a similar14C lipid content but a greater14C cholesterol content was found in the intestinal tissue of rats fed corn oil than in rats fed lard for 10 days. After a longer
period of feeding of 25 days, the intestinal tissue14C cholesterol level was decreased in the corn oil fed rats without any significant effect on other lipids. These data suggest
that corn oil in some way influences cholesterol biosynthesis depending upon its degree of unsaturation and the period of
time for which it is fed. The decrease at the later time might involve some mechanism which aids in getting rid of accumulated
tissue cholesterol. Less14C lipid and14C cholesterol were released by the intestinal tissue of rats fed the unsaturated fat as compared with those fed the saturated
fat, suggesting a possible role in vivo in reducing blood lipids and blood cholesterol levels.
Robert A. Welch Foundation. 相似文献
20.
Normal and streptozotocin diabetic rats were injected via the portal vein with a labeled solution containing3H arachidonic acid and14C linoleic acid (3H/14C ratio, 0.5) during a 1 min period. Livers were quickly frozen, pulverized, and the lipids extracted and fractioned by thin
layer chromatography. The incorporation of3H and14C into liver lipids was measured and the percentage distribution of radioactivity into the different lipid fractions was determined.
The incorporation of14C linoleic acid and3H arachidonic acid into liver lipids is apparently reduced in rats with severe diabetes. The higher3H/14C ratio found in the 1,2 diglycerides from diabetic rats may be explained by the apparently smaller incorporation of14C linoleic acid or by an isotopic dilution attributable to the great availability of this acid in diabetic rats. On the other
hand, the higher3H/14C ratio observed in triglycerides and phospholipids from diabetic rats, due to a relatively large incorporation of3H arachidonic acid into this fraction, may be explained by the affinity of the enzymes involved in their synthesis for some
1,2-diglyceride units. Insulin was unable to correct the changes observed in the diabetic rats. 相似文献