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1.
Omega-3 fatty acids influence the function of the intestinal brush border membrane. For example, the omega-3 fatty acid eicosapentaenoic
acid (20∶5ω3) has an antiabsorptive effect on jejunal uptake of glucose. This study was undertaken to determine whether the
effect of feeding α-linolenic acid (18∶3ω3) or EPA plus docosahexaenoic acid (22∶6ω3) on intestinal absorption of nutrients
was influenced by the major source of dietary lipid, hydrogenated beef tallow or safflower oil. Thein vitro intestinal uptake of glucose, fatty acids and cholesterol was examined in rats fed isocaloric diets for 2 weeks: beef tallow,
beef tallow + linolenic acid, beef tallow + eicosapentaenoic acid/docosahexaenoic acid, safflower oil, safflower oil + linolenic
acid, or safflower oil + eicosapentaenic acid/docosahexaenoic acid. Eicosapentaenoic acid/docosahexaenoic acid reduced jejunal
uptake of 10 and 20 mM glucose only when fed with beef tallow, and not when fed with safflower oil. Linolenic acid had no
effect on glucose uptake, regardless of whether it was fed with beef tallow or safflower oil. The jejunal uptake a long-chain
fatty acids (18∶0, 18∶2ω6, 18∶3ω3, 20∶4ω6, 20∶5ω3 and 22∶6ω3) and cholesterol was lower in salfflower oil than with beef tallow.
When eicosapentaenoic acid/docosahexaenoic acid was given with beef tallow (but not with safflower oil), there was lower uptake
of 18∶0, 20∶5ω3 and cholesterol. The demonstration of the inhibitory effect of linolenic acid or eicosapentaenoic acid/docosahexaenoic
acid on cholesterol uptake required the feeding of a saturated fatty acid diet (beef tallow). These changes in uptake were
not explained by differences in the animals’ food intake, body weight gain or intestinal weight. Feeding safflower oil was
associated with an approximately 25% increase in the jejunal and ileal mucosal surface area, but this increase was prevented
by combining linolenic acid or eicosapentaenoic acid/docosahexaenoic acid with safflower oil. Different inhibitory patterns
were observed when mixtures of fatty acids were present together in the incubation medium, rather than in the diet: for example,
when 18∶0 was in the incubation medium with 20∶4ω6, the uptake of 20∶4ω6 was reduced, whereas the uptake was unaffected by
18∶2ω6 or 20∶5ω3. Thus, (1) the inhibitory effect of eicosapentaenoic acid/docosahexaenoic acid on jejunal uptake of glucose,
fatty acids and cholesterol was influenced by the major dietary lipid, saturated (beef tallow) or polyunsaturated fatty acid
(safflower oil); and (2) different omega-3 fatty acids (linolenic acid versus eicosapentaenoic acid/docosahexaenoic acid)
have a variable influence on the intestinal absorption of nutrients. 相似文献
2.
Thirteen-day old rats were given intracranial injections of 1-14C linolenic acid (allcis 9,12,15 octa decatrienoic acid) and were sacrificed after 8 hr. Analysis of brain fatty acids showed that 16∶0, 18∶0, 18∶1,
18∶3, 20∶3, 20∶4, 20∶5, 22∶5, and 22∶6 were labeled. The total fatty acid methyl esters were separated into classes according
to degree of unsaturation on a AgNO3∶SiO2 impregnated plate. The bands were scraped off and the eluted fatty acids were first analyzed by radiogas liquid chromatography
and then subjected to reductive ozonolysis to determine double bond position. The saturated acids, 16∶0, and 18∶0, as well
as the mono-unsaturated 18∶1, must have been formed from radioactive acetate produced by β oxidation of the injected linolenate.
Among the polyunsaturated fatty acids, the triene fraction was characterized and identified as 18∶3 ε3 (Δ9,12,15), the starting material, and 20∶3 ω3 (Δ11,14,17); the tetraene fraction was identified as 20∶4 ω3 (Δ8,11,14,17); the pentaene fraction was identified as 20∶5 ω3 (Δ5,8,11,14,17) and 22∶5 ω3 (Δ7,10,13,16,19); and, finally, the hexaene fraction was shown to be 22∶6 ω3 (Δ4,7,10,13,16,19). The biosynthesis of these ω3 family fatty acids in the brain in situ is discussed. 相似文献
3.
Effects of parenteral nutrition with high doses of linoleate on the developing human liver and brain
The developmental changes in the fatty acid composition of ethanolamine phosphoglycerides (EPG) and choline phosphoglycerides
(CPG) were studied in the liver and brain of 18 newborn infants with gestational ages ranging from 20 to 44 wk. A small group
of five newborns receiving total parenteral nutrition (TPN) with high doses of linoleic acid (18∶2ω6) was also studied and
compared to controls of the same gestational age to look for effects on the developmental fatty acid patterns of liver and
brain EPG and CPG. TPN with Intralipid 20% was given for 4–12 days, the total fat intake being 14.7–90 g (mean ±S.D.=47.1±29.8
g). The main developmental changes in the liver and brain of the control group were an increase in 22∶6ω3 (docosahexaenoic
acid) at the end of gestation and a linear decrease in 20∶4ω6 (arachidonic acid) and 18∶1ω9 (oleic acid) in EPG and CPG. A
very good correlation in the percent values of these fatty acids in the brain and liver tissues was obtained. Very significant
changes in the fatty acid composition of liver EPG and CPG could be found in the infants receiving TPN with Intralipidmainly
an increase in 18∶2ω6, a decrease in the linoleate elongation/desaturation to longer members of the series and a decrease
in the 22∶6ω3 levels of liver EPG and CPG. In the brain, only an increase in the 18∶2ω6 value of CPG, not accompanied by any
increase in the longer ω6 fatty acids, could be detected. Possible adverse effects of high doses of 18∶2ω6 on the tissue levels
of long chain polyunsaturated fatty acids (PUFA), especially of 22∶6ω3, are discussed. 相似文献
4.
Michael D. Peck Emilio Mantero-Atienza Maria Jose Miguez-Burbano Mary Ann Fletcher Gail Shor-Posner Marianna K. Baum 《Lipids》1993,28(7):593-597
Previous studies have shown that alterations in micronutrient utilization occur in patients with Acquired Immune Deficiency
Syndrome. In this study, total plasma fatty acid composition was measured in 36 homosexual men infected with the Human Immunodeficiency
Virus 1 (HIV-1) and in 17 HIV-1 seronegative homosexual men in order to evaluate differences associated with early HIV-1 infection.
Immunologic assessment included CD4 cell number count and lymphocyte blastogenesis in response to the mitogens phytohemagglutinin
(PHA) and pokeweed (PWM). The mean total amount of ω6 polyunsaturated fatty acids (18∶2 and 20∶4) was significantly lower
in the HIV-1 seropositive subjects (38±8.1% SD) as compared to HIV-1 seronegative subjects (43±4.2%;P=0.0027). This was also reflected in a higher level of total saturated fatty acids (16∶0 and 18∶0) in HIV-1 seropositive subjects
(30±2.2%vs. 26±2.8%;P=0.0001). The ratio of linoleic to arachidonic acid (18∶2 to 20∶4) was higher in the HIV-1 seronegative group (6.76±4.88)
compared to the HIV-1 seronegative group (4.86±1.37;P=0.0213). The response to PHA in seropositive subjects correlated inversely with total plasma ω6 fatty acids (r=−0.36;P=0.027), and directly with the 18∶2 to 20∶4 ratio (r=0.33;P=0.046). CD4 cell counts and the response to PWM did not correlate with plasma fatty acid levels in HIV-1 seropositive subjects.
We conclude that early HIV-1 infection is associated with lower plasma ω6 polyunsaturated fatty acids, notably arachidonic
acid, than are controls, and that the changes in the plasma fatty acid profile correlate with some indices of immune function. 相似文献
5.
Diets rich in meat are claimed to contribute to the high tissue arachidonic acid (20∶4ω6) content in people in Westernized
societies, but there are very few direct data to substantiate this assertion. Because meat contains a variety of long-chain
polyunsaturated fatty acids (PUFA) that are susceptible to oxidation, we initially examined the effect of cooking on the long-chain
PUFA content of beef, and then determined the effect of ingestion of lean beef on the concentration of long-chain PUFA in
plasma phospholipids (PL). First, we examined the effect of grilling (5–15 min) and frying (10 min) different cuts of fat-trimmed
lean beef on the long-chain PUFA content. Second, we investigated the effect of including 500 g lean beef daily (raw weight)
for 4 wk on the fatty acid content and composition of plasma PL in 33 healthy volunteers. This study was part of a larger
trial investigating the effect of lean beef on plasma cholesterol levels. In the first two weeks, the subjects ate a very
low-fat diet (10% energy) followed by an increase in the dietary fat by 10% each week for the next 2 wk. The added fat consisted
of beef fat, or olive oil (as the oil or a margarine) or safflower oil (as the oil or a margarine). This quantity of beef
provided 60, 230, 125, 140 and 20 mg/d, respectively, of eicosatrienoic acid (20∶3ω6), 20∶4ω6, eicosapentaenoic acid (20∶5ω3),
docosapentaenoic acid (22∶5ω3) and docosahexaenoic acid (22∶6ω3). Grilling for 10–15 min, but not frying, of the fat-trimmed
lean beef resulted in 20–30% losses of the 20 and 22 carbon PUFA. The consumption of the lean beef during the first two-week
period, when there was a very low level of dietary fat, was associated with significant increases in the proportion and concentration
of 20∶3ω6, 20∶4ω6, 20∶5ω3 and 22∶5ω3 in the plasma PL and a significant decrease in the proportion and content of 18∶2ω6.
The addition of beef fat or olive oil to the diets containing lean beef did not alter the plasma PL fatty acid profile compared
with the very low-fat diet, whereas the addition of safflower oil maintained the significant increases in 20∶4ω6 and 22∶5ω3
but led to decreases in 18∶3ω3 and 20∶5ω3 compared with the very lowfat diet. The results showed that diets rich in lean beef
increased the 20∶3ω6, 20∶4ω6 and the long-chain ω3 PUFA levels in the plasma PL. A high level of linoleic acid in diets rich
in lean beef prevented the rise in the plasma level of 20∶3ω6 and 20∶5ω3, two fatty acids known to antagonize the effects
of 20∶4ω6 on platelet aggregation. 相似文献
6.
The fatty acid composition of testicular lipids has been determined and related to fertility data from groups of dubbed White
Leghorn cockerels after a 50-week feeding period on rations containing 10% safflower oil or coconut oil. Supplements of ethoxyquin
ord-α-tocopherol acetate maintained fertility in birds raised on rations containing safflower oils. This response was associated
with higher proportions of 22∶4 ω6 and lower proportions of 18∶2 ω6 in testicular lipids. Testes size was quite variable in
the unsupplemented group with changes in fatty acid composition being more pronounced in the smaller testes. A multiple regression
was calculated using data from those birds on the safflower oil ration. With a correlation ratio of 0.90 fertility was expressed
as a function of testes size, semen concentration and the proportions of 18∶2 ω6, 20∶4 ω6 and 22∶4 ω6 in testicular lipids.
Despite the low intake of linoleate significant levels of polyunsaturated fatty acids were maintained in testicular lipids
of birds fed the coconut oil rations. The major changes in fatty acid composition of testicular lipids produced by this variable
was a decrease in the proportion of 18∶2 ω6 and an increase in the proportion of 18∶1.
Paper No. 3050, Oregon Agricultural Experiment Station. 相似文献
7.
The acyl composition of ethanolamine and choline phosphoglycerides from a series of human brain tumors was determined and
compared to that of normal human gray matter. Six glioblastomas, one astrocytoma, one oligodendroglioma, and one meningioma
were analyzed. The total fatty acid composition of ethanolamine phosphoglycerides generally had a higher percentage of 18∶1,
18∶2ω6, and 22∶5ω3 and a lower percentage of 22∶6ω3 than that of normal gray matter. Choline phosphoglycerides from the tumors
also contained a higher than normal percentage of 18∶2ω6. Separate analysis of the acyl groups at the 2 position of the diacyl
and ether-linked components of the phosphoglycerides revealed that the diacyl component of ethanolamine phosphoglyceride from
the tumors had lower than normal amount of 22∶6ω3 and a higher than normal amount of 18∶1 and 18∶2ω6. The acyl composition
of ether-linked ethanolamine phosphoglycerides genearally contained a higher percentage of 20∶4ω6 and a lower percentage of
18∶1 compared to the corresponding fraction from normal gray matter. The astrocytoma analyzed had fatty acid profiles similar
to those of the control with the exception of a greater 18∶2ω6 content. These data demonstrate that the composition of the
acyl moiety at the 2 position of diacyl and ether-linked phosphoglycerides of brain tumors differs from the corresponding
component from normal gray matter and that the ether-linked ethanolamine phosphoglycerides provide an important pool of polyunsaturated
fatty acids from brain tumor phospholipids. 相似文献
8.
Existence of a dietary maximal level or threshold for incorporation of ω3 fatty acids into membrane phospholipids is of interest
as it may further define understanding of the dietary requirement for ω3 fatty acids. To test whether feeding increasing levels
of dietary ω3 fatty acids continues to increase membrane ω3 fatty acid content, weanling rats were fed a nutritionally adequate
semipurified diet which provided increasing amounts of C20 and C22 ω3 fatty acids, such as 20∶5ω3 and 22∶6ω3. Dietary 20∶5ω3 and 22∶6ω3 were provided by substituting a purified shark oil concentrate
of high 22∶6ω3 content for safflower oil high in 18∶2ω6. After four weeks of feeding, nuclear envelopes from four animals
in each diet group were prepared, lipid was extracted and phospholipids separated. Arachidonic acid content in membrane phosphatidylcholine,
phosphatidylethanolamine, phosphatidylinositol and phosphatidylserine was significantly reduced by feeding increased dietary
levels of ω3 fatty acids. Decline of 20∶4ω6 level in phospholipid tended to stabilize when the dietary content of total ω3
fatty acids reached 4–5% of total fatty acids. Above this level, dietary ω3 fatty acids did not result in a further decrease
in membrane content of 20∶4nω6. Increase in membrane phospholipid content of 20∶5ω3 occurred as the dietary intake of ω3 fatty
acids increased from 1.1% to 5% of total fatty acids. A dietary ω3 fatty acid level of 2.2–3% was sufficient to result in
maximum incorporation of 22∶6ω3 into membrane phosphatidylcholine and phosphatidylethanolamine, but not into phosphatidylinositol
or phosphatidylserine. 相似文献
9.
The activity of the overt form of rat liver mitochondrial carnitine palmitoyltrasferase or CPT0 (EC 2.3.1.21) towards different fatty acid substrates was studied. The following non-esterified fatty acids (NEFA) and their
CoA esters in the presence of 1% bovine serum albumin (BSA) were tested: 16∶0, 18∶0, 18∶1, 18∶2, 18∶3ω3, 20∶4, 20∶5ω3 and
22∶6ω3. The data fit a square hyperbolic model for enzyme catalysis (p<0.001, non-linear regression). Asymptotic Vmax and K0.5, substrate concentration at one-half Vmax, were calculated using total concentrations of acyl-CoA, or unbound concentrations of NEFA. BSA was found to act as a true
substrate reservoir for NEFA in that the dissociation of the NEFA-BSA complex was 10–330 times faster than the CPT0 reaction. Regardless of form (NEFA or CoA ester), 18∶3ω3 gave the highest, while 22∶6ω3 and 18∶0 gave the lowest rates of
acylcarnitine synthesis. Except for 18∶3ω3 and 18∶2, Vmax for NEFA was generally lower than for acyl-CoA, with the greates differences observed for 20∶4, 20∶5ω3 and 22∶6ω3, suggesting
that acyl-CoA synthesis may also be important in the control of the entry of these fatty acids into the mitochondria. The
data provide an enzymatic rationale for the relatively low content of 18∶3ω3 in esterified lipid. 相似文献
10.
Donald L. Smith Anthony L. Willis Ngoc Nguyen Debra Conner Shaye Zahedi Judy Fulks 《Lipids》1989,24(1):70-75
Studies in man and laboratory animals suggest that ω3 polyunsaturated fatty acid consituents of fish oils have antiatherosclerotic
properties. We have studied the effects of several such polyunsaturated fatty acids for ability to modify the in vitro release
of mitogens from human platelets. Such mitogens may produce the fibroproliferative component of atherosclerotic plaques. Both
5,8,11,14,17-eicosapentaenoic acid (20∶5ω3) and 4,7,10,13,-16,19-docosahexaenoic acid (22∶6ω3), major constituents of fish
oils, inhibited adenosine diphosphate-induced aggregation of platelets and the accompanying release of mitogens. These effects
are dose dependent. Linolenic acid (18∶3ω3), the biosynthetic precursor of eicosapentaenoic acid, also inhibited platelet
aggregation and mitogen release. Eicosapentaenoic acid also inhibited mitogen release from human monocyte-derived macrophages,
which, in vivo, are an additional source of mitogens during atherogenesis.
Potent inhibition of human platelet aggregation and mitogen release was also seen with dihomo-γ-linolenic acid (8,11,14-eicosatrienoic
acid 20∶3ω6), whose levels are reportedly elevated in Eskimos subsisting on marine diets.
We conclude that diets that elevate plasma and/or tissue levels of eicosapentaenoic acid, docosahexaenoic acid and dihomo-γ-linolenic
acid precursor γ-linolenic acid (18∶3ω6) may exert antiatherosclerotic effects by inhibiting the release of mitogens from
platelets and other cells. 相似文献
11.
Weanling male rats were fed hydrogenated coconut oil to induce essential fatty acid (EFA) deficiency. After 15 weeks, the
rats were divided into six groups. Five groups were fed graded amounts of purified linolenate (18∶3ω3) with a constant amount
of linoleate (18∶2ω6) for six weeks. Fatty acid composition was determined in brain lipids. Increasing dietary 18∶3ω3 resulted
in a decrease in arachidonic acid (20∶4ω6), docosatetraenoic acid (22∶4ω6) and docosapentaenoic acid (22∶5ω6), whereas 18∶2ω6
and eicosatrienoic acid (20∶3ω6) were increased both in total lipids and phospholipids. These results suggest that dietary
18∶3ω3 exerts its inhibitory effect mainly on the desaturation of 20∶ω6 to 20∶4ω6 in brain lipids. Linolenate was undetectable
in brain lipids from any dietary treatments. The levels of eicosapentaenoic acid (20∶5ω3) in groups receiving dietary 18∶3ω3
were not different from that of the group receiving no 18∶3ω3. These results indicate that, in the brain, 18∶3ω3 is rapidly
converted mainly to 22∶6ω3 without being accumulated and imply that dietary 18∶3ω3 can modulate the level of precursor of
diene prostaglandins (PG) but not that of triene PG in the rat brain. 相似文献
12.
Methyl linolenate 18∶3ω3 and docosahexaenoate 22∶6ω3 were incorporated in semipurified diets at several levels and fed to
trout previously maintained on a fat-free diet. After 14 weeks, the weight gain and feed conversion of the fish on each diet
were determined. The fatty acid composition of the lipid from each group of fish was analyzed by gas liquid chromatography.
Both 18∶3ω3 and 22∶6ω3 fed at the 1% level supported maximum growth of the fish. The control group, which were fed no ω3 fatty
acids, exhibited a shock syndrome, poor appetite and a very slow growth rate. Tissue fatty acid analysis revealed eicosatrienoic
acid 20∶3ω9 accumulated in the phospholipid fraction of this group. The 20∶3ω9 level was lowered when either 18∶3ω3 or 22∶6ω3
was included in the diet. Analysis showed that the dietary 18∶3ω3 was rapidly converted by the fish into 22∶6ω3 with a high
concentration in the phospholipid. However 22∶6ω3 fed to the fish remained unchanged and little or no retroconversion of this
fatty acid was observed.
Presented in part at the AOCS Meeting, Atlantic City, October 1971.
Technical paper no. 3247, Oregon Agricultural Experiment Station. 相似文献
13.
Male weanling rats were fed semi-synthetic diets high in saturated fat (beef tallow) vs high in linoleic acid (safflower oil)
with or without high levels of α-linolenic acid (linseed oil) for a period of 28 days. The effect of feeding these diets on
cholesterol content and fatty acid composition of serum and liver lipids was examined. Feeding linseed oil with beef tallow
or safflower oil had no significant effect on serum levels of cholesterol. Serum cholesterol concentration was higher in animals
fed the safflower oil diet than in animals fed the beef tallow diet without linseed oil. Feeding linseed oil lowered the cholesterol
content in liver tissue for all dietary treatments tested. Consumption of linseed oil reduced the arachidonic acid content
with concomitant increase in linoleic acid in serum and liver lipid fractions only when fed in combination with beef tallow,
but not when fed with safflower oil. Similarly, ω3 fatty acids (18∶3ω3, 20∶5ω3, 22∶5ω3, 22∶6ω3) replaced ω6 fatty acids (20∶4ω6,
22∶4ω6) in serum and liver lipid fractions to a greater extent when linseed oil was fed with beef tallow than with safflower
oil. The results suggest that the dietary ratio of linoleic acid to saturated fatty acids or of 18∶3ω3 to 18∶2ω6 may be important
to determine the cholesterol and arachidonic acid lowering effect of dietary α-linolenic acid. 相似文献
14.
The effects of dietary n−3 and n−6 polyunsaturated fatty acids on the fatty acid composition of phospholipid, Ca++· Mg++ ATPase and Ca++ transport activities of mouse sarcoplasmic reticulum were investigated. Mice were fed a 2 weight percent fat diet containing
either 0.5 weight percent ethyl esters of 18∶3n−3, 20∶5n−3 or 22∶6n−3 as a source of n−3 polyusaturated fatty acid or 0.5
weight percent safflower oil as a cource of n−6 polyunsaturated fatty acid for 10 days. Olive oil (2 weight percent) was used
as a control diet. Although feeding n−6 polyunsaturated fatty acid induced very little modifications of the phospholipid sarcoplasmic
reticulum fatty acid composition, feeding n−3 polyunsaturated fatty acid altered it markedly. Inclusion of 18∶−3, 20∶5n−3
or 22∶6n−3 in the diet caused an accumulation of 22∶6n−3, which replaced 20∶4n−6 and 18∶2n−6 in phospholipid sarcoplasmic
reticulum. The saturated fatty acids were significantly increased with a concurrent reduction of 18∶1n−9. These changes in
the fatty acid composition resulted in a decrease in the values of the n−6/n−3 polyunsaturated fatty acid ratio and a decrease
in the ratio of 20 carbon to 22 carbon fatty acids esterified in the phospholipid sarcoplasmic reticulum. This was associated
with a decrease in Ca++ uptake by n−3 polyunsaturated fatty acid enriched sarcoplasmic reticulum vesicles as compared with n−6 fatty acid and control
diet sarcoplasmic reticulum vesicles. However, neither the affinity for Ca++ nor the maximal velocity of ATP hydrolysis activity of Ca++·MG++ ATPase were altered by the different diets. The data suggest that the incorporation of 22∶6n−3 and/or the decrease of 20∶4n−6
plus 18∶2n−6 in the phospholipid sarcoplasmic reticulum may affect the membrane lipid bilayer structure and make it more permeable
to Ca++. 相似文献
15.
Pre-term infants, that are not breast-fed, are deprived of vital intrauterine fat accretion during late pregnancy and must
rely on formula to obtain fatty acids essential for normal development, particularly of the visual system. Preterm infants
(30 wk postconception) receiving human milk were compared to infants given one of the following formulae: Formula A was a
commercial preterm formula with predominantly 18∶2ω6 (24.2%) and low (0.5%) 18∶3ω3; Formula B was based on soy oil and contained
similar 18∶2ω6 levels (20%) and high 18∶3ω3 (2.7%); Formula C was also a soy oil-based formula (20% 18∶2, 1.4% 18∶3) but was
supplemented with marine oil to provide ω3 long-chain polyunsaturated fatty acids (LCP) at a level (docosahexaenoic acid,
DHA, 0.35%) equivalent to human milk. At entry (10 days of age), the fatty acid composition of plasma and red blood cell (RBC)
membrane lipids of the formula groups were identical. By 36 wk postconception, the DHA content in lipids of group A was significantly
reduced compared to that in the human milk and marine oil formula groups. Omega-3 LCP results were further amplified by 57
wk with compensatory increases in 22∶5ω6 in both plasma and RBC lipids. Provision of 2.7% α-linolenic acid in formula group
B was sufficient to maintain 22∶6ω3 levels equivalent to those in human milk-fed infants at 36 wk but not at 57 wk. Effects
on the production of thiobarbituric acid reactive substances and fragility of RBC attributable to the marine oil supplementation
were negligible. The results support the essentiality of ω3 fatty acids for preterm infants to obtain fatty acid profiles
comparable to infants receiving human milk. Formula for preterm infants should be supplemented with ω3 fatty acids including
LCP.
Based on a paper presented at the Symposium on Milk Lipids held at the AOCS Annual Meeting, Baltimore, MD, April 1990. 相似文献
16.
The effects of the mixedcis- 18∶1 isomers and mixedtrans-18∶1 isomers present in partially hydrogenated soybean oil (PHSO) upon the patterns of polyunsaturated fatty acids (PUFA)
in liver phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were studied in rats fed concentrates ofcis- 18∶1 ortrans- 18∶1 isomers isolated as triacylglycerides from PHSO. Thecis- 18∶1 andtrans- 18∶1 concentrates were fed at levels equal to those present in PHSO fed at 17.9% of the diet. All diets contained the required
amounts of both linoleic and linolenic acids. Thetrans- 18∶1 concentrate was found to suppress the levels of 20∶4ω6 and 20∶3ω9, and to increase the levels of 18∶2ω6 and 20∶5ω3
in PC and PE. Thecis- 18∶1 concentrate suppressed 20∶4ω6 in PC, 20∶5ω3 in PC and PE, and 18∶2ω6 was more effective than thetrans concentrate in suppressing 22∶6ω3. Thetrans- 18∶1 concentrate was more effective in suppressing 20∶4ω6. Thetrans-18∶ isomers appear to modify PUFA metabolism by inhibition of PUFA synthesis, whereas thecis- 18∶1isomers appear to compete with 2-position fatty acyl transfer and to inhibit ω3 PUFA acylation. 相似文献
17.
This study examined the effect on the plasma lipids and plasma phospholipid and cholesteryl ester fatty acids of changing
from a typical western diet to a very low fat (VLF) vegetarian diet containing one egg/day. The effect of the addition of
saturated, monounsaturated or polyunsaturated fat (PUFA) to the VLF diet was also examined. Three groups of 10 subjects (6
women, 4 men) were fed the VLF diet (10% energy as fat) for two weeks, and then in the next two weeks the dietary fat in each
group was increased by 10% energy/week using butter, olive oil or safflower oil. The fat replaced dietary carbohydrate. The
VLF diet reduced both the low density lipoprotein (LDL)-and high density lipoprotein (HDL)-cholesterol levels; addition of
the monounsaturated fats and PUFA increased the HDL-cholesterol levels, whereas butter increased the cholesterol levels in
both the LDL- and HDL-fractions. The VLF diet led to significant reductions in the proportion of linoleic acid (18∶2ω6) and
eicosapentaenoic acid (20∶5ω3) and to increases in palmitoleic (16∶1), eicosatrienoic (20∶3ω6) and arachidonic acids (20∶4ω6)
in both phospholipids and cholesteryl esters. Addition of butter reversed the changes seen on the VLF diet, with the exception
of 16∶1, which remained elevated. Addition of olive oil resulted in a significant rise in the proportion of 18∶1 and significant
decreases in all ω3 PUFA except 22∶6 compared with the usual diet. The addition of safflower oil resulted in significant increases
in 18∶2 and 20∶4ω6 and significant decreases in 18∶1, 20∶5ω3 and 22∶5ω3. These results indicate that the reduction of saturated
fat content of the diet (<6% dietary energy), either by reducing the total fat content of the diet or by exchanging saturated
fat with unsaturated fat, reduced the total plasma cholesterol levels by approximately 12% in normocholesterolemic subjects.
Although the VLF vegetarian diet reduced both LDL- and HDL-cholesterol levels, the long-term effects of VLF diets are unlikely
to be deteterious since populations which habitually consume these diets have low rates of coronary heart disease. The addition
of safflower oil or olive oil to a VLF diet produced favorable changes in the lipoprotein lipid profile compared with the
addition of butter. The VLF diets and diets rich in butter, olive oil or safflower oil had different effects on the 20 carbon
eicosanoid precursor fatty acids in the plasma. This suggests that advice on plasma lipid lowering should also take into account
the effect of the diet on the fatty acid profile of the plasma lipids. 相似文献
18.
The lipid composition of the yellow clam,Mesodesma mactroides, that lives in the northern beaches of the Buenos Aires province of Argentina was studied. The main nonpolar lipids are triglycerides
and alkoxyglycerides. Phosphatidyl choline, phosphatidyl ethanolamine, and phosphatidyl serine are the main phospholipids.
The predominant fatty acids are 16∶0, 16∶1ω7, 18∶0, 18∶1ω9, 20∶5ω3, and 22∶6ω3. The are mainly provided by the clam's food
and stored in the hepatopancreas. The content of polyunsaturated acids increases in summer together with an increase in nonpolar
lipids and is correlative with an increase in phytoplankton in the sea water. Sexual maturity modifies the lipid composition
of gametes. 相似文献
19.
Cats fed a diet containing linoleate as the only polyunsaturated fatty acid showed extremely low levels of arachidonate in
the plasma lipids, as well as an increase in linoleate, eicosadienoate and an unknown fatty acid. Administration of [1-14C] linoleic acid and [2-14C] eicosa-8,11,14-trienoic acid to cats showed that in the liver there was no conversion of the [1-14C] 18∶2 to arachidonate, whereas there was significant metabolism of [2-14C] 20∶3 to arachidonate. It was found when methyl-γ-linolenate was fed to cats that the level of 20∶3ω6 and 20∶4ω6 in the
erythrocytes increased significantly. These results show that there is no significant Δ6 desaturase activity in the cat, whereas
chain elongation and Δ5 desaturase enzymes are operative. The unknown fatty acid was isolated from the liver lipids and shown
to be a 20-carbon fatty acid with 3 double bonds and which by gas liquid chromatography could be separated from 20∶3ω9 and
20∶3ω6. The presence of the Δ5-desaturase activity and the results of the ozonolysis studies indicated that this unknown fatty
acid was eicosa-5,11,14-trienoic acid. 相似文献
20.
Rat peri-renal and epididymal pre-adipocytes in culture undergoing triglyceride (TG) accumulation were incubated with oleic
(18∶1), linoleic (18∶2), α-linolenic (18∶3ω3), arachidonic (20∶4) and 4,7,10,13,16,19-docasahexaenoic (22∶6ω3) acids in the
presence of 0.8 μM insulin. The fatty acids were incorporated in cellular TG with relative enrichments over control from 1.4-fold
for 18∶1 to greater than 40-fold for 18∶3ω3. Greater than 80% of fatty acids taken up were incorporated into cellular TG.
The balance was distributed, in decreasing amounts, into phospholipids, unidentified intracellular constituents, and ketone
bodies. The P/S ratio of cellular TG was at least an order of magnitude lower than that of the external milieu for both cell
types and for all treatment groups, including controls. Doubling the concentration of treatment fatty acid increased its incorporation
into cellular TG. However, it did not affect the accumulation of the other fatty acids in TG. Epididymal cells consistently
acquire a higher proportion of treatment fatty acids in cell TG than peri-renal cells. Pre-adipocytes with polyunsaturated
fatty acids (PUFA)-enriched TG is a potential model for the study of PUFA metabolism in these types of cells 相似文献