151
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Abstract
Lysolecithin (lysoglycerophosphocholine, LPC) was isolated from rat cerebral cortex and quantitatively analyzed at various times after postdecapitative ischemic treatment. In addition, different procedures for extraction and analysis of the LPC in brain were evaluated. Results indicated that LPC can be quantitatively extracted into the organic phase using the conventional extraction procedure with chloroform-methanol (2:1, vol/vol). However, care should be taken to avoid using strong acids, which can hydrolyze the alkenylether side chain of the plasmalogens, resulting in the release of 2-acylphospholipids. Quantitative GLC analysis using myristoyl-LPC as internal standard revealed a level of 1.8 nmol LPC/mg protein in brain with acyl groups comprised mainly of 16:0, 18:0, and 18:1. The acyl group profile reflects that the LPC are derived mainly from phospholipase A2 action. An increase of 46% in the LPC level was observed at 1 min after ischemic treatment, but this was followed by a steady decline. Ischemia induced an increase in the LPC species that are enriched in 18:0 and 18:1 fatty acids. The transient appearance of LPC during ischemia further suggests that this phospholipid is undergoing active turnover, possibly hydrolysis by the lysophospholipase. This mechanism of action may account, at least in part, for the increase in both saturated and unsaturated fatty acids during the early phase of the ischemic treatment.
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152
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Abstract
Ethanol consumption was correlated with changes in acyl group profiles of phosphatidylcholine and triacylglycerols in serum of Sinclair(S-1) miniature boars. Serum triacylglycerols in the control pigs were high in linoleate (18:2) (48%) and low in stearate (18:0 (3%). Upon feeding with 10% (w/v) ethanol ad lib for two weeks, the proportion of 18:2 in serum triacylglycerols decreased to 12-15% with a concomitant increase in 16:0, 18:0 and 18:1. Similar, but less extensive, acyl group changes were observed in the serum phosphatidylcholine. In addition, there was a decrease in the proportion of 20:3(n-6), but a biphasic change was shown in 20:4(n-6) with respect to ethanol consumption. In general, the high ethanol consumers (7.0 g/kg/day) indicated a more rapid rate of acyl group change than the low consumers (3.8 g/kg/day). Upon withdrawal of ethanol, acyl groups of triacylglycerols rapidly returned towards the control values, whereas only small changes were observed for the recovery in phospholipids. In this situation, the low-consumer group indicated a more rapid recovery than the high-consumer group. Results indicate that with the swine model, serum lipid changes can be a useful parameter for correlating biological changes upon ethanol consumption.
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153
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Abstract
In the presence of Ca2+ (2.5 mM) and using [14C]arachidonoyl phosphatidylinositol (PI) membrane as substrate, phosphatidylinositol-specific phospholipase C (PI-PLC) (EC 3.1.4.10) in rat brain synaptosomes was activated by deoxycholate but not taurocholate. Calcium stimulated enzymic hydrolysis by both detergents, but the stimulatory effect of taurocholate was less than that of deoxycholate. Peak stimulation for deoxycholate was observed at 1 mg/ml, whereas that for taurocholate was 4 mg/ml. When 1 mM EDTA was added to the taurocholate (4 mg/ml) and Ca2+ (3.5 mM) system, synaptosomal PI-PLC activity was greatly stimulated, to almost the same level as the deoxycholate + Ca2+ system. This system required the presence of all three factors, and EGTA could not effectively replace EDTA in the stimulatory action. The detergent-induced hydrolysis of synaptosomal PI by the deoxycholate + Ca2+ and the taurocholate + Ca2+ + EDTA systems was strongly inhibited by divalent metal ions such as Zn2+, Cu2+, Pb2+, and Fe2+, whereas Mg2+ and Ca2+ were ineffective. Nevertheless, only the deoxycholate + Ca2+ system was responsive to enzyme inhibition by membrane-perturbing agents such as lysophospholipids and free fatty acids. The specific requirement for EDTA in the taurocholate system may be due to the release of a pool of inhibitory divalent metal ions from the membranes.
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154
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Sun GY, Sun AY. Chronic ethanol administration induced an increase in phosphatidylserine in guinea pig synaptic plasma membranes. Biochem Biophys Res Commun 1983; 113:262-8. [PMID: 6860339 DOI: 10.1016/0006-291x(83)90460-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Chronic ethanol administration to guinea pigs via intragastric intubation elicited a specific increase (50%) in phosphatidylserine in the synaptic plasma membrane. The ethanol-treated group also showed a 53% increase in synaptosomal (Na,K)-ATPase activity. Analysis of the acyl group composition of individual phospholipids in the same membrane fraction revealed only small changes which varied depending on the type of phospholipids. Since the (Na,K)-ATPase is known to be specifically activated by phosphatidylserine, the adaptive increase in enzyme activity during chronic ethanol treatment may be related to the increase in this type of negatively charged phospholipid.
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155
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Abstract
1. Substantial differences were found in the acyl donor and lyso-acceptor specificities among subcellular membranes and with respect to different regions of the adrenal gland. 2. In the presence of Mg2+-ATP and CoASH, adrenal microsomes were actively transferring arachidonate to lysophospholipids with acyl acceptor specificity in the order: 1-acyl-GPI greater than 1-acyl-GPC greater than 1-acyl-GP. However, when oleoyl-CoA was used, acyl acceptor specificity for the microsomal transferases was in the order: 1-acyl-GPC greater than 1-acyl-GP greater than 1-acyl-GPI. 3. Mitochondrial membranes had very low acyl transfer activity and they preferred 1-acyl-GPC over other lyso-acceptors. 4. The chromaffin granules were apparently lacking this type of activity.
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156
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Strosznajder J, Foudin L, Tang W, Sun GY. Serum albumin washing specifically enhances arachidonate incorporation into synaptosomal phosphatidylinositols. J Neurochem 1983; 40:84-90. [PMID: 6401324 DOI: 10.1111/j.1471-4159.1983.tb12656.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Arachidonate incorporation into synaptosomal phospholipids was shown to be affected by factors including the procedure for preparation of the membrane fractions and preincubation of synaptosomes prior to assay of incorporation of arachidonate into both phosphatidylcholine (PC) and phosphatidylinositol (PI). However, the inhibition toward incorporation into PIs, but not PCs, was fully reversed when the membranes were washed with bovine serum albumin. A twofold increase in arachidonate incorporation into PIs was also observed when freshly prepared synaptosomes were washed with serum albumin immediately before assay of incorporation activity. The inhibitory action is thought to be due to an increase in polyunsaturated fatty acids and/or their oxidation products which may then elicit a special effect on the acyltransferase responsible for transferring arachidonate into phosphatidylinositols. The differences in fatty acid uptake and response to serum albumin also suggest the presence of different acyltransferase for acyl transfer to PIs and PCs.
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157
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Strosznajder J, Tang W, Manning R, Lin AY, MacQuarrie R, Sun GY. Metabolism of oleoyl-CoA in rat brain synaptosomes: effects of calcium and post-decapitative ischemia. Neurochem Res 1981; 6:1231-40. [PMID: 6123958 DOI: 10.1007/bf00966680] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The hydrolysis of acyl-CoA by acyl-CoA hydrolase (EC 3.1.2.2.) in brain synaptosomes was inhibited by calcium. This inhibition was partly due to interaction of Ca2+ with the acyl-CoA, which was present in the soluble form, and partly due to complex formation among acyl-CoA, Ca2+ and membrane phospholipids. The inhibition of acyl-CoA hydrolase activity, as well as the complex formation, could be reversed if incubation was carried out in the presence of Ca2+ chelating agents. Synaptosomes isolated from brain samples after 1 min of postdecapitative treatment showed a decrease in oleoyl-CoA hydrolase activity. The physiological implication of acyl-CoA metabolism in relation to synaptic function is discussed.
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158
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Abstract
The effects of 1 min of acute hypoxic treatment (1% O2 in N2) on incorporation of [1-14C]arachidonic acid into brain lipids of 16-day-old rats were investigated at 3, 6, and 12 min after intracerebral injection of the labeled fatty acid. The hypoxic-hypoxia condition associated with convulsive seizures caused a decrease in the conversion of labeled arachidonate to its acyl-CoA as well as incorporation of the label into the brain phospholipids. Among the phospholipids, there was a specific decrease in the labeling of diacylglycerophosphoinositol (GPI), and this change was accompanied by an increase in labeling of the diacylglycerols. These results indicate that metabolism of the long-chain fatty acids and some glycerolipids in brain are vulnerable to acute hypoxic treatment.
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159
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Abstract
Synaptosomal phosphoglycerides were labeled after incubation with [1-14C]arachidonic acid, ATP, Mg2+, CoASH, and a small amount of 1-acylglycerophosphocholines. Under this incubation system, radioactivity was directed largely to diaclyglycerophosphocholines but diacylglycerophosphoinositols were also labeled to a lesser extent. Synaptosomes obtained after a 5-min ischemic treatment indicated a decrease (10-20%) in incorporation of radioactivity into the phospholipids. The ischemic synaptosomes also tended to retain a larger portion of the labeled arachidonate during the wash with bovine serum albumin. Upon incubation of the prelabeled synaptosomes in a sucrose-Tris (pH 7.4) medium at 37 degrees C, a time-dependent release of labeled arachidonate from the phospholipids was observed in both control and ischemic samples. Arachidonate release from the prelabeled synaptosomes was not affected by EDTA (1 mM) or taurocholate (0.4%) but was stimulated by Ca2+ (2.5 mM) or Ca2+ (3.5 mM) together with EDTA (1 mM). After incubation at 37 degrees C for 1 hr without added factors, the phospholipid degradation, as well as the appearance of free fatty acids, were higher in the ischemic samples (especially after 1 min of treatment) as compared to controls.
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160
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Abstract
An acute administration of chlorinated water to rats caused "fatty liver" and indicated a more than 2-fold increase in liver triacylglycerols at 2 days after administration. The acyl group composition of triacylglycerols and phospholipids in both liver mitochondria and liver whole homogenate were also altered by the chlorine treatment. Among the phospholipid acyl groups, there was an increase in the proportion of 20:4 but a decrease in most other polyunsaturated acyl groups. The acyl group changes were more obvious with phosphatidylcholines than with phosphatidylethanolamines. Other phospholipids, including cardiolipin in the mitochondrial membranes, were not greatly altered. Both morphological and biochemical changes were maximum at 2 days after the treatment and were fully recovered after 10 days. The disturbance of a number of enzymatic processes in the liver membranes may account for a large part of the changes observed.
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161
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Abstract
Incubation of synaptosomes together with 1-acyl-2-[14C]arachidonoyl-sn-glycerophosphoinositols (GPI) and sodium deoxycholate yielded diacylglycerols and free arachidonic acid. Diacylglycerol formation is attributed to hydrolysis by the diacyl-GPI-specific phospholipase C (EC 3.1.4.10), and this reaction requires sodium deoxycholate for optimal activity. The free arachidonic acid formed is attributed to hydrolysis of diacyl-GPI by phospholipase A (EC 3.1.1.5). Free fatty acid release was observed during incubation, even in the absence of bile salts, but this process was preferentially stimulated by sodium taurocholate. The release of fatty acids was not specific for diacyl-GPI, as similar release was obtained during incubation with other phosphoglycerides. In the presence of deoxycholate (2 mg/ml), the release of diacylglycerols was maximal at a diacyl-GPI concentration around 1.0 mM. However, the free fatty acid release was linear with respect to the substrate at least up to 1.4 mM. The rate of diacylglycerol release from diacyl-GPI was more rapid in the initial 30 min, whereas the free fatty acid release was linear with time up to 2 h. Under this incubation condition, calcium was found to stimulate both types of hydrolytic action, although the concentration needed to achieve this stimulation was rather high. This type of labeled precursor is potentially useful for studies of the different modes of diacyl-GPI degradation by enzymes in brain subcellular membranes.
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162
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Abstract
The enzymic hydrolysis of oleoyl-CoA in rat brain cytosol and the acyltransferase-mediated transfer of acyl-CoA to 1-acyl-glycerophosphates and 1-acyl-glycerophosphocholines by brain microsomes were examined at various stages of brain development. Although the amount of cytosolic protein (per gram weight) in brain decreased steadily with age during development, specific activity of the acyl-CoA hydrolase in this fraction increased nearly onefold during the first 2 weeks of age before exhibiting a steady decline until maturation. The amount of microsomes isolated from brain increased during the 1st week of age but started to decline steadily thereafter. Specific activity of the oleoyl-CoA transfer to 1-acylphospholipids by brain microsomes seemed to remain rather constant throughout the 1st month of age but they showed an increase at around 29 days of age before dropping to a steady level after reaching adult age.
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163
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Sun GY, Manning R, Strosznajder J. Effects of postdecapitative ischemia and hypoxia on the phosphoglyceride acyl groups of rat brain membranes. Neurochem Res 1980; 5:1211-9. [PMID: 7464984 DOI: 10.1007/bf00964900] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Rats subjected to mild hypoxic and postdecapitative ischemic treatments indicated a decrease (8-16%) in the proportion of polyunsaturated acyl groups of diacyl glycerophosphocholines (diacyl-GPC), diacyl glycerophosphoethanolamines (diacyl-GPE), and alkenylacyl glycerophosphoethanolamines (alkenylacyl-GPE) in brain synaptosomes. In general, the acyl group changes due to mild hypoxic treatment were less obvious than those due to the ischemic treatment. The decrease in polyunsaturated acyl groups was marked by an increase in the saturated (16:0 and 18:0) and monoenoic (18:1) acyl groups. Among the polyunsaturated acyl groups, arachidonate (20:4) indicated the greatest decrease in response to ischemic and hypoxic treatments. The decrease in polyunsaturated fatty acids of diacyl glycerophosphocholines was largest in the first minute of ischemic treatment and the first 30 min of hypoxic treatment. After the initial decrease, there was a slight recovery. The biphasic type of change was thought to be due to active reacylation of the lyso phospholipids. This biphasic change, however, was not observed with ethanolamine phosphoglycerides which indicated a steady decrease in the polyunsaturated acyl group content with time of ischemic treatment. The increased hydrolysis of polyunsaturated acyl groups in brain membrane phosphoglycerides due to the ischemic and hypoxic treatments seemed to correlate well with the implication of phospholipase A(2) involvement in eliciting the increase in free fatty acids during brain stimulation.
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164
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Wise RW, Sun GY, Macquarrie R. The kinetic properties of oleoyl-CoA:1-acyl-sn-glycero-3-phosphocholine O-acyltransferase from mouse-brain microsomes. Eur J Biochem 1980; 109:201-6. [PMID: 7408877 DOI: 10.1111/j.1432-1033.1980.tb04785.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The kinetic properties of acylation of 1-acyl-sn-glycero(-3)phosphocholine by oleoyl-CoA were examined using mouse brain microsomes. The enzyme-catalyzed reactions were studied by measuring the rate of reaction while systematically varying the concentrations of oleoyl-CoA and 1-acylglycerophosphocholine. Double reciprocal plots of velocity versus 1-acylglycerophosphocholie produced a family of parallel lines and similar plots for oleoyl-CoA produced a family of parallel curves. Inhibition was observed at high concentrations of either substrate. By extrapolation from low substrate concentrations, the V for oleoyl-CoA:1-acylglycerophosphocholine acyltransferase in brain microsomes was found to be 6.1 nmol min-1 mg-1 and Km values were determined to be 11 microM and 107 microM for oleoyl-CoA and 1-acylglycerophosphocholine, respectively. Similar results were obtained for the enzyme-catalyzed transfer of oleoyl groups to 1-acyl-sn-glycerophosphoinositol. In this case, V was found to be 2.1 nmol min-1 mg-1 and the Km values were 4 microM and 14 microM for oleoyl-CoA and 1-acylglycerophosphoinositol, respectively. The mechanistic implications of the kinetic properties of the acyltransferases with respect to acyl group specificity for the phosphoglycerides in brain microsomes are discussed.
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165
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Sun GY, Smith RE, Chan K, MacQuarrie R. Inhibition of acyl-CoA hydrolase activity in liver microsomes by lyso-phospholipids. Biochem Biophys Res Commun 1980; 94:1278-84. [PMID: 6104963 DOI: 10.1016/0006-291x(80)90558-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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166
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167
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168
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Sun GY, Sun AY. Effect of chronic ethanol administration on phospholipid acyl groups of synaptic plasma membrane fraction isolated from guinea pig brain. Res Commun Chem Pathol Pharmacol 1979; 24:405-8. [PMID: 572577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Guinea pigs were induced chronic alcoholism with a liquid diet containing 5% (w/v) ethanol. There was no apparent change in acyl group composition in the myelin lipids; however, acyl group changes were observed in the phosphoglycerides of synaptic plasma membranes (SPM). In general, acyl group changes are related to a decrease in the proportion of monoenes in both choline and ethanolamine phosphoglycerides and an increase in polyenes (15%) in the ethanolamine phosphoglycerides. The changes observed may be associated to the increased membrane-dependent transport activities observed after chronic ethanol treatment.
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169
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170
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171
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172
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Sun GY, Corbin DR, Wise RW, MacQuarrie R. Effects of lipid intermediates, lyso-glycerophospholipids and detergents on arachidonate transfer to 1-acyl-glycerophospholipids by brain synaptosomes. Int J Biochem 1979; 10:557-63. [PMID: 456731 DOI: 10.1016/0020-711x(79)90014-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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173
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Abstract
The purpose of this study was to evaluate the effects of large amounts of dietary vitamin E and butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) in rabbits fed a low-cholesterol, atherogenic diet, and to seek for evidence of lipid peroxidation in the atherosclerotic lesions. Rabbits were fed a purified atherogenic diet, containing butter or the basal diet supplemented with either 1.0% of vitamin E or 0.1% each of BHA and BHT for periods up to 3 years; a negative control group was fed the basal diet with corn oil replacing butter. Aortic and coronary atherosclerosis were more frequent and extensive in rabbits fed either the basal diet or the basal diet supplemented with BHA and BHT than in rabbits fed either the basal diet supplemented with vitamin E or the negative control diet. Dietary vitamin E inhibited atherogenesis by preventing hypercholesterolemia. No evidence of lipid peroxidation was detected in the arterial lesions.
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174
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Su KL, Sun GY. Acyl group composition of metabolically active lipids in brain: variances among subcellular fractions and during postnatal development. J Neurochem 1978; 31:1043-7. [PMID: 702135 DOI: 10.1111/j.1471-4159.1978.tb00145.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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175
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Sun GY, Sun AY. The effects of chronic ethanol administration on acyl group composition of mitochondrial phospholipids from guinea pig adrenal. Res Commun Chem Pathol Pharmacol 1978; 21:355-8. [PMID: 694232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The acyl groups of diacyl-glycerophosphocholine1 (GPC) and diacyl-glycerophosphoethanolamine (GPE) in guinea pig adrenals are comprised mainly of 16:0, 18:0, 18:1, 18:2 and 20:4(n-6) with only trace amounts of the longer chain polyunsaturated fatty acids. There was an increase in the proportions of 18:2 and a decrease in the 20:4(n-6) of diacyl-GPC and diacyl-GPE with respect to chronic ethanol administration. Acyl group changes were more obvious in diacyl-GPC than in diacyl-GPE. It is conceivable that these changes may lead to an alteration of other membrane transport activities as well as functions of the adrenal gland.
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176
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177
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178
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Samorajski T, Strong JR, Sun GY, Sun AY, Seamen R. Dihydroergotoxine and ethanol: physiological and neurochemical variables in male mice. Gerontology 1978; 24 Suppl 1:43-54. [PMID: 145392 DOI: 10.1159/000212297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The residual effects of dihydroergotoxine mesylate (DHET: active substance of Hydergine), ethanol, and DHET + ethanol were investigated in aging male mice. Prolonged alcohol or DHET consumption was found to prolong hexobarbital sleeping time and increase oxygen consumption. Administration of alcohol combined with DHET inhibited the ability of each drug to prolong hexobarbital sleeping time and increase oxygen consumption. There were no significant differences between groups in forebrain synaptosomal (Na+-K+) adenosine- triphosphatase and acetylcholinesterase activity or cerebellar protein, DNA and RNA content. The relative proportion of phospholipid to protein in isolated myelin of the medulla was significantly reduced, whereas the sphingomyelin content of total phospholipid was highest in alcohol-treated mice. Conocomitant treatment of mice with alcohol combined with DHET prevented the physiological and neurochemical changes caused by alcohol and, in some cases, DHET, administered alone.
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179
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180
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Abstract
The metabolism of a polyunsaturated and a saturated fatty acid in brain membrane phosphoglycerides was examined by injecting simultaneously a mixture of 14C-arachidonate and 3H-stearate into the mouse brain and isolating the microsomal and synaptosomal fractions at 1-40 min after injections. Both types of labeled fatty acids were utilized more readily in the microsomal than the synaptosomal fractions in brain. However, labeled arachidonate was incorporated more rapidly into membrane phosphoglycerides than was stearate. In both subcellular fractions, the relative specific radioactivity (3H and 14C) of diacyl-glycerophosphorylinositol (diacyl-GPI) was higher than other types of phosphoglycerides such as diacyl-glycerophosphorylcholine (diacyl-GPC) and diacyl-glycerophorylethanolamine (diacyl-GPE). Furthermore, the apparent rates of incorporation of radioactivity into diacyl-GPI was more rapid for the 14C-arachidonate than for the 3H-stearate. Results of the experiment have demonstrated obvious differences in metabolism between stearate and arachidonate in brain. The more rapid transfer of arachidonate to diacyl-GPI is probably due to the presence of an acyl transferase system specially active for the transfer of arachidonyl groups to diacyl-GPI.
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182
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Sun GY, Creech DM, Corbin DR, Sun AY. The effect of chronic ethanol administration on arachidonyl transfer to 1-acyl-glycerophosphorylcholine in rat brain synaptosomal fraction. Res Commun Chem Pathol Pharmacol 1977; 16:753-6. [PMID: 860087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Enzymatic transfer of arachidonate to synaptosomal diacyl-GPC in a group of rats (n=14) administered 30% ethanol by intragastric intubation for 21 days was 24% higher than controls (n=5) (P less than 0.05). No apparent difference in enzymic activity was observed with respect to different periods of withdrawal (8-24 hrs). The acyl transferase activity in another group of rats (n=5) which were given 15% ethanol as the sole drinking source for 13 months was 58% higher than controls (P less than 0.025). The increase in acyl transferase activity with respect to the two types of chronic ethanol administration may be due to an adaptive mechanism in brain to facilitate the increase in membrane transport activities which are known to occur under the influence of ethanol.
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183
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Leung BS, Sun GY. Acyl group composition of membrane phospholipids in mammary tissues and carcinoma induced by dimethylbenz(a)anthracene. Exp Biol Med (Maywood) 1976; 152:671-6. [PMID: 184477 DOI: 10.3181/00379727-152-39465] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Phospholipids and their acyl group composition in mammary adenocarcinomas and mammary tissue of the same tumor-bearing animals were investigated. Breast adenocarcinoma induced by dimethybenz(a)anthracene exhibited a phospholipid pattern which was different from that of the mammary tissue. Tumor phospholipids had higher proportions of diacyl-GPI, diacyl-GPE, and alkenylacyl-GPE and a lower proportion of diacyl-GPC than the controls. The acyl groups of most phospholipids in tumors showed a marked increase in the proportion of 18:1 and a decrease in the proportion of 18:2. The fatty acid composition of plasmalogen and triglyceride, however, remained unchanged. In spite of the decrease in the proportion of 18:2, there was no apparent difference in the proportion of 20:4 in most of the phosphoglycerides; however, a significant decrease in this fatty acid was noted in diacyl-GPI. Results of this study demonstrated that the membrane phospholipids of mammary adenocarcinoma were altered in respect to acyl group composition. Changes in physical properties of the cell membrane, in turn, could lead to abnormal manifestation of membrane regulated events in tumor cells.
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184
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185
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Sun GY, Leung BS. Changes in phospholipids and acyl group composition of rat mammary gland during pregnant, lactating, and post-weaning periods. Lipids 1976; 11:322-7. [PMID: 1263775 DOI: 10.1007/bf02544061] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The distribution of phospholipids as well as their fatty acid compositions of rat mammary tissues were examined during pregnant, lactating, and post-weaning periods. There was no apparent change in phospholipids and their acyl groups during the early and late pregnant periods. However, tissue phospholipid composition was different during pregnant, early, and late lactating periods. After parturition, there was a marked increase in the proportion of diacyl-glycerophosphorylcholine in the phospholipids of mammary tissue, but this proportion decreased gradually during lactation. The decrease in diacyl-glycerophosphorylcholine during lactation was marked by a corresponding increase in diacyl-glycerophosphorylethanolamie. Although the shorter chain fatty acids of triglycerides were increased during lactation, only a small proportion of these fatty acids was found in the phosphoglycerides. Marked changes in acyl group composition of individual phospholipids are found during these different physiological stages. In general, there was a rapid decrease in 20:4 and an increase in 18:2 in the major phosphoglycerides during parturition. The proportion of 20:4 in the phosphoglycerides remained low throughout the entire lactating period, while that of 18:2 continued to increase 2-3 fold. Most of the changes in acyl group of the phosphoglycerides during lactation returned to normal ca. 10 days after weaning. A possible relationship of the variation of phospholipid and acyl group compositions in mammary tissue to changes in hormonal pattern during different physiological stages is discussed.
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186
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Sun GY, Yau TM. Changes in acyl group composition of diacyl-glycerophosphorylethanolamine, alkenylacyl-glycerophosphorylethanolamine and diacyl-glycerophosphorylcholine in myelin and microsomal fractions of mouse brain during development. J Neurochem 1976; 26:291-5. [PMID: 1255192 DOI: 10.1111/j.1471-4159.1976.tb04479.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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187
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189
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Sun GY, Leung BS. Phospholipids and acyl groups of subcellular membrane fractions from human intracranial tumors. J Lipid Res 1974; 15:423-31. [PMID: 4369007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The phospholipids from subcellular fractions of human intracranial tumors were examined. For comparison, microsomes were isolated from a fetal human brain and from the gray matter of adult human brains. The subcellular membranes of tumors had a higher protein-to-phospholipid ratio than the normal brain membranes. The microsomes from tumors had a lower proportion of diacylglycerophosphorylethanolamine and higher proportions of alkenylacylglycerophosphorylcholine and sphingomyelin (plus diacylglycerophosphorylinositol) than microsomes from the gray matter. Also, the ratios of alkenylacylglycerophosphorylethanolamine to diacylglycerophosphorylethanolamine were higher in the tumors than in the normal controls. The acyl groups of ethanolamine phosphoglycerides in tumor microsomes had relatively more 18:1, 18:2, and 20:4(n - 6) and less 18:0, 22:4(n - 6), and 22:6(n - 3) than the adult brain gray matter. Except for the increase in 18:2, acyl group changes in choline phosphoglycerides between tumors and controls were not as extensive as in the ethanolamine phosphoglycerides. The characteristic features of phospholipids and their constituent acyl groups of tumors were often present in all the subcellular fractions. Although the acyl group profiles of the tumor phosphoglycerides were in closer resemblance to the fetal brain than to the adult brain, other differences were observed. Results indicate that neoplastic brain cells are unique in their cellular composition, and consequently they deviate from the normal neurons and glials in metabolism and functions.
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Sun GY, Go J, Sun AY. Induction of essential fatty acid deficiency in mouse brain: effects of fat deficient diet upon acyl group composition of myelin and synaptosome-rich fractions during development and maturation. Lipids 1974; 9:450-4. [PMID: 4407652 DOI: 10.1007/bf02534270] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Sun GY, Sun AY. Synaptosomal plasma membranes: acyl group composition of phosphoglycerides and (Na+ plus K+)-ATPase activity during fatty acid deficiency. J Neurochem 1974; 22:15-8. [PMID: 4362076 DOI: 10.1111/j.1471-4159.1974.tb12173.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Sun GY. Phospholipids and acyl groups in subcellular fractions from human cerebral cortex. J Lipid Res 1973; 14:656-63. [PMID: 4742559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Subcellular fractionation of human brain cortex obtained at autopsy yielded microsomal and synaptosome-rich fractions from the gray matter and microsomal and purified myelin fractions from the white matter. The phospholipids of myelin were high in plasmalogens, and the molar ratio of alkenyl acyl sn-glycero-3-phosphorylethanolamine to diacyl sn-glycero-3-phosphorylethanolamine was 4. The acyl groups of the myelin phosphoglycerides were enriched in monoenes (mainly 18:1 and 20:1) and a tetraene, 22:4(n - 6). The phospholipids in the synaptosome-rich fraction were high in diacyl sn-glycero-3-phosphorylcholine, and the molar ratio of the alkenyl acyl sn-glycero-3-phosphorylethanolamine to diacyl sn-glycero-3-phosphorylethanolamine was 0.88. The acyl groups of synaptosomal ethanolamine phosphoglycerides were rich in 22:6(n - 3) but contained a very low amount of 20:1. The lipid composition of microsomes from the gray matter was different from that of microsomes from the white matter but was nearly identical with that of the synaptosome-rich fraction. Except for a slightly lower proportion of alkenyl acyl sn-glycero-3-phosphorylethanolamine and sphingomyelin, the lipid composition of microsomes from the white matter was also similar to that of the myelin. There were also species-related differences between the brain lipid composition of human and subhuman primates and that of the rodents. Furthermore, the brain lipid composition in normal human subjects is rather constant and does not seem to be affected much by individual variations.
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Sun GY, Samorajski T. Age differences in the acyl group composition of phosphoglycerides in myelin isolated from the brain of the rhesus monkey. Biochim Biophys Acta 1973; 316:19-27. [PMID: 4352921 DOI: 10.1016/0005-2760(73)90162-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Sun GY, Horrocks LA. Metabolism of palmitic acid in the subcellular fractions of mouse brain. J Lipid Res 1973; 14:206-14. [PMID: 4698268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
After an intracerebral injection of [(14)C]palmitic acid to C57BL/10J mice, the radioactivity in the brains decreased rapidly with time. The incorporated radioactivity was primarily in the 16:0 acyl groups of the diacyl phosphoglycerides at 1 and 3 days after injection. At longer times, increasing proportions of the radioactivity were found in cerebrosides, alkenyl groups, and other acyl groups. The specific radioactivities of the phosphoglycerides were highest in the microsomal fraction at 1 day after injection. The exchange of the diacyl glycerophosphorylcholines and diacyl glycerophosphorylethanolamines between the microsomes and the myelin required 8-14 days. When calculated on the basis of the radioactivity in the 16:0 acyl groups, the half-lives for both of these phosphoglycerides were 6-8 days in all subcellular fractions during the period from 14 to 30 days after injection. The radioactivity in the total lipids from the purified myelin fraction did not decline until more than 14 days after injection because of the reutilization of labeled 16:0 acyl groups for lipid biosynthesis. Recycling of the acyl groups explains the long half-lives reported for myelin phosphoglycerides after injection of [(14)C]acetic acid. Lipids with a relatively high specific radioactivity were lost from the myelin fraction during the purification procedure. The most likely source of these lipids is the most recently formed myelin that is not consolidated into the myelin sheath.
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Sun GY, Sun Y. Phospholipids and acyl groups of synaptosomal and myelin membranes isolated from the cerebral cortex of squirrel monkey (Saimiri sciureus). Biochim Biophys Acta 1972; 280:306-15. [PMID: 4345143 DOI: 10.1016/0005-2760(72)90098-7] [Citation(s) in RCA: 108] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Sun GY, Samorajski T. Age changes in the lipid composition of whole homogenates and isolated myelin fractions of mouse brain. J Gerontol 1972; 27:10-7. [PMID: 5009181 DOI: 10.1093/geronj/27.1.10] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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