bluuebunny/crossref_metadata_2025_split huggingface dataset:
Arachidonic acid, prostaglandin E2 and leukotriene C4 levels in gingiva and submandibular salivary glands of rats fed diets containing n−3 fatty acids
Authors: Alam S. Q. , Bergens B. M. , Alam B. S. 
Published: November 2006

AbstractThe effect of dietary n−3 fatty acids on prostaglandin E2 (PGE2) and leukotriene C4 (LTC4) levels in rat salivary glands and gingiva was examined in two separate nutritional studies. In the first set of experiments, two groups of male weanling Sprague‐Dawley rats were fed semipurified diets containing 10% corn oil (control group) or 10% menhaden oil (experimental group). Rats were killed after 8 wk on the diets; the fatty acid composition of total phospholipids and the concentrations of PGE2 and its precursor, arachidonic acid, were measured in gingiva and submandibular salivary glands (SMSG). Dietary n−3 fatty acids were incorporated into the tissue phospholipids. Arachidonic acid levels were reduced by 56% in gingiva and SMSG of rats fed menhaden oil compared with the control rats fed the diet containing corn oil. The concentrations of PGE2 in SMSG and gingiva of rats fed the diet containing menhaden oil were reduced by 74% and 83%, respectively. In a subsequent nutritional study, we tested whether the diet‐induced reduction in tissue arachidonic acid levels would also result in a corresponding decrease in LTC4 production. Three groups of rats were fed diets containing 5% corn oil (group 1), 4% ethyl ester concentrate of n−3 fatty acids plus 1% corn oil (group 2), or 5% ethyl ester concentrate of n−3 fatty acids (group 3). After 6 wk of feeding, gingiva and SMSG were analyzed for arachidonic acid content andin vitro production of LTC4. Arachidonic acid content of total phospholipids was about 60% lower in gingiva and 69% lower in SMSG of rats fed the ethyl ester concentrate of n−3 fatty acids (groups 2 and 3) than those of the control group fed the corn oil diet (group 1). Upon incubation with calcium ionophore, gingiva and SMSG from rats fed the n−3 fatty acids rich diet produced significantly less TLC4 than those from rats of the control group. Because PGE2 and LTC4 are believed to be important biochemical mediators of periodontal disease, one may speculate that a diet‐induced reduction in their levels may have a beneficial effect upon the course of the disease. The function of salivary glands may also be altered because of the role of these eicosanoids in salivary secretions.
Cholesterol metabolism in the rat lactating mammary gland: The role of cholesteryl ester hydrolase
Authors: Botham Kathleen M. 
Published: November 2006

AbstractAn acid cholesteryl ester hydrolase activity associated with a fraction containing mitochondria and lysosomes from rat lactating mammary glands was found to have a pH optimum of 5.0. Its sedimentation pattern was closely related to that of the lysosomal enzyme markers acid phosphatase and β‐glucuronidase, suggesting that the activity is associated with the lysosomes. The enzyme was strongly inhibited by Cu2+, but was inhibited little by other divalent metal ions. Acid cholesteryl ester hydrolase activity was almost completely abolished byp‐hydroxymercuribenzoate, but this effect was reversed in the presence of an equimolar concentration of reduced glutathione (GSH), indicating that the enzyme requires free sulfhydryl groups for activity. These properties are similar to those of acid, lysosomal cholesteryl ester hydrolases found in other tissues. Acid cholesteryl ester hydrolase activity was 8–14 fold higher in mammary tissue from lactating as compared to virgin rats. Neutral cholesteryl ester hydrolase activities associated with the microsomal and cytosolic subcellular fractions were also increased in lactating glands, but to a lesser extent. In addition, a 2‐fold increase in the activities of both the acid and microsomal neutral enzymes was seen during the first few days of lactation, while the cytosolic neutral activity remained constant. These results suggest that mammary gland cholesteryl ester hydrolases have a role in the regulation of cholesterol metabolism in mammary cells, and in the provision of cholesterol for secretion into milk.
Effects of perturbations in hepatic free and esterified cholesterol pools on bile acid synthesis, cholesterol 7α‐hydroxylase, HMG‐CoA reductase, acyl‐CoA:Cholesterol acyltransferase and cytosolic cholesteryl ester hydrolase
Authors: Grogan W. M. , Bailey M. L. , Heuman D. M. , Vlahcevic Z. R. 
Published: November 2006

AbstractEffects of expansion of the hepatic free cholesterol pool on bile acid and cholesterol metabolism and homeostasis were examined in rats fed cholesterol in high‐fat diets or treated with oleyl‐p‐(n‐decyl)‐benzenesulfonate (ODS) or progesterone. Cholesterol feeding for 10–16 days, which increased free (33%) and esterified (6‐fold) cholesterol, had no effect on cholate synthesis, total bile acid synthesis, or cholate turnover, whereas these activities were increased 60–80% by ODS and progesterone, which produced only small increases (19%) in free cholesterol. Cholesterol feeding reduced β‐hydroxy‐β‐methylglutaryl (HMG)‐CoA reductase (72%) and cholesteryl ester hydrolase (48%) and increased acyl‐CoA:cholesterol acyltransferase (184%), whereas ODS and progesterone reversed these compensatory responses in cholesterol‐fed rats. Cholesterol 7α‐hydroxylase was changed no more than 22% by any treatment. A bolus of ODS elevated biliary cholesterol output 41% and shifted biliary bile acid synthesis and composition toward 12‐deoxy bile acids. These effects were not seen in ODS‐fed or progesterone‐treated rats, in which cholesteryl ester stores were depleted. It is concluded that effects of free cholesterol on bile acid synthesis and biliary cholesterol are probably mediated by specific precursor or regulatory pools which can be independently regulated and which represent a relatively small fraction of hepatic free cholesterol.
Free sterols, steryl esters, and lipid phosphorus in needles of scot's pine (Pinus sylvestris L.)
Authors: Fischer Christine , Höll Wolfgang 
Published: November 2006

AbstractFree sterols, steryl esters, and lipid phosphorus were measured in new (current year) needles of Scot's pine during an annual cycle, and also in one‐, two‐, and three‐year‐old needles collected shortly after bud break. Sterols were identified and quantified by capillary gas chromatography and gas chromatography/mass spectrometry. Steryl esters were hydrolyzed enzymatically. Newly emerged needles contained highest amounts of free sterols and lipid phosphorus, probably reflecting increased membrane and organelle production, but low levels of steryl esters. Mature needles contained approximately equal amounts of free and esterified sterols. The molar phospholipid/free sterol ratio was 3∶1 at all the time periods studied. A dramatic increase of steryl esters was observed in the one‐, two‐, and three‐year‐old needles at times when new needles emerged. The individual free and esterified sterols were sitosterol, campesterol (presumably together with its C‐24 epimer), and cholesterol, at approximately 88, 10, and 2%, respectively. Isofucosterol, an intermediate in sitosterol biosynthesis, was present almost exclusively in newly emerged needles. Esterified sterols contained only trace amounts of isofucosterol. Shifts in favor of cholesterol and 24ζ‐methyl cholesterol occurred in the steryl esters during needle differentiation, and saturation grade of esterified fatty acids decreased. In mature needles, the composition of free sterols and steryl esters remained constant throughout the year.
Selected ion monitoring gas chromatography/mass spectrometry of 1,2‐diacylglyceroltert‐butyldimethylsilyl ethers derived from glycerophospholipids
Authors: Ohshima Toshiaki , Koizumi Chiaki 
Published: November 2006

AbstractSelected ion monitoring was used in conjunction with gas chromatography/mass spectrometry to analyzetert‐butyldimethylsilyl ethers (tert‐BDMS) of 1,2‐diacyl‐sn‐glycerols derived from naturally occurring glycerophospholipids, including those ofEscherichia coli, soybean, egg yolks and porcine liver. First, the fatty acid composition of the unknown glycerophospholipid was determined by gasliquid chromatography (GLC) and, based on that, the fatty acids (mostly >0.5 wt%) were selected for monitoring the characteristic fragmentation ions produced from the fatty acid residues of the correspondingtert‐BDMS derivatives of 1,2‐diacyl‐sn‐glycerols. Next, thetert‐BDMS derivatives were separated by GLC on a 65% methylphenylsilicone gum wall‐coated open‐tubular (WCOT) column according to the degree of unsaturation and the chain length of the fatty acid residues, and then directly introduced into the ion source of the mass spectrometer. The selected fragmentation ions, [RCO+74]+ representative of the fatty acid residues, and [M‐57]+ indicative of the molecular weight of the derivatives, were monitored simultaneously. It thus became possible to determine the molecular species of thetert‐BDMS derivatives by measuring a specific combination of two [RCO+74]+ and an [M‐57]+ ion with the same retention time on the selected ion monitoring (SIM) profile. High background noise caused by volatilization of stationary phase at high temperature was largely overcome by selected ion monitoring. However, the fragmentation ion peaks produced fromtert‐BDMS derivatives of highly unsaturated glycerophospholipids showed a distorted SIM profile, which was attributed to interaction between thetert‐BDMS derivatives and the methylphenylsilicone phase of the column. Use of a WCOT column with a more polar liquid phase is therefore recommended for the analysis of highly unsaturated molecular species.
Double‐bond localization in heneicosapentaenoic acid by a gas chromatography/mass spectrometry (GC/MS) method
Authors: Yamamoto Kohei , Shibahara Akira , Nakayama Takao , Kajimoto Goro 
Published: November 2006

AbstractDouble‐bond locations in heneicosapentaenoic acid from eel lipids were determined by a method involving gas chromatography/mass spectrometry (GC/MS). The methyl esters of the pentaenoate fraction were first partially reduced with hydrazine. The resultingcis‐monoenoates were then methylthiolated, and the resultant adducts were analyzed by GC/MS. The key fragmentation ions generated by the cleavage between the methylthio‐substituted carbons were used to ascertain the original double‐bond positions in the native fatty acid esters. Based on mass spectral evidence, the acid was identified as all‐cis‐6,9,12,15,18‐heneicosapentaenoic acid.
Maternally‐supplied fish oil alters piglet immune cell fatty acid profile and eicosanoid production
Authors: Fritsche Kevin L. , Alexander David W. , Cassity Nancy A. , Huang Shu‐Cai 
Published: November 2006

AbstractThis study was designed to examine the incorporation of omega‐3 (n−3) fatty acids into the immune tissues of pigs nursing fish oil‐fed sows and to determine the effect of maternal dietary n−3 consumption onin vitro immune cell eicosanoid production. On day 107 of gestation, 12 sows were randomly allotted to a diet containing either 7% menhaden fish oil (MFO) or lard (LRD). The fatty acid profile of serum, liver, thymus, splenocytes and alveolar macrophages (AM) of 18–21‐day‐old pigs was significantly affected by the fat source provided to the sow. Arachidonic acid (20∶4n−6) content was typically reduced by more than 50% in MFO as compared with LRD pigs. In MFO pigs, eicosapentaenoic acid (20∶5n−3) was the major n−3 polyunsaturated fatty acid, and its levels matched or exceeded those of arachidonic acid. Basal release of prostaglandin E, thromboxane B and leukotriene B by AM was 60–70% lower in MFOvs. LRD pigs. However, when these immune cells were stimulated with calcium ionophore A23187, release of leukotriene B was similar in MFO and LRD pigs. In conclusion, substituting MFO for LRD in a sow's late‐gestation and lactation diet greatly elevated the content of n−3 fatty acids in the nursing pig immune cells and generally reducedin vitro eicosanoid release by pig immune cells.
Metabolic behavior in rats of a nonprotein microemulsion resembling low‐density lipoprotein
Authors: Maranhão Raul C. , Cesar Thais B. , Pedroso‐Mariani Suzana R. , Hirata Mario H. , Mesquita Carlos H. 
Published: November 2006

AbstractA protein‐free microemulsion (LDE) with a lipid composition resembling that of low‐density lipoprotein (LDL) was used in metabolic studies in rats to compare LDE with the native lipoprotein. LDE labeled with radioactive lipids was injected into the bloodstream of male Wistar rats, and plasma kinetics of the labeled lipids were followed on plasma samples collected at regular intervals for 12 h after injection. The 24‐h LDE uptake by different tissues was also measured in tissue samples excised after the animals had been sacrificed. We found that LDE plasma kinetics were similar to those described for native LDL [fractional clearance rate (FCR) of cholesteryl ester, 0.42±0.11 h−1]. The major site for LDE uptake was the liver, and the tissue distribution of the LDE injected radioactivity was as one would expect for LDL. To test whether LDE was taken up by the specific LDL receptors, the LDE emulsion was injected into rats treated with 17α‐ethinylestradiol, which is known to increase the activity of these receptors; as expected, removal of LDE from the bloodstream increased (FCR=0.90±0.35 h−1). On the other hand, saturation of the receptors that remove remnants by prior infusion of massive amounts of lymph chylomicrons did not change LDE plasma kinetics. These results indicate that LDE is cleared from plasma by B,E receptors and not by the E receptors that remove remnants. Incorporation of free cholesterol into LDE increased LDE plasma clearance. Incubation studies also showed that LDE incorporates a variety of apolipoproteins, including apo E, a ligand for recognition of lipoproteins by specific receptors. Our data suggest that LDE can be a useful tool to test LDL metabolism and B,E receptor function.
Effect of regulating cholesterol biosynthesis on breath isoprene excretion in men
Authors: Stone Bradford G. , Besse Timothy J. , Duane William C. , Dean Evans C. , DeMaster Eugene G. 
Published: November 2006

AbstractIsoprene is a normal constituent of human breath and may be derived from the cholesterol synthetic pathway. Acute and chronic lovastatin and a cholesterol‐supplemented diet were used to determine whether a mechanistic link exists between isoprene and cholesterol biosynthesisin vivo in humans. The acute effects of lovastatin, a competitive inhibitor of the rate‐limiting step of cholesterol biosynthesis, on breath isoprene excretion was determined by administering a single 20, 40 or 80 mg dose of this drug to five healthy male subjects at 8 p.m. and measuring their breath isoprene levels every 4 h for one 24 h cycle before and after treatment. When compared to the baseline cycle, all three doses of lovastatin significantly reduced breath isoprene levels at 6 and 10 h post‐drug treatment. Chronic lovastatin therapy (40 mg b.i.d. for 6 wk) reduced 6 a.m. breath isoprene levels (time of maximum baseline value) by 27 ± 9% (SEM) and cholesterol synthesis measured in freshly isolated mononuclear leukocytes (ML) by 12 ± 6%. A cholesterol‐supplemented diet (1070 mg, total) ingested for 6 wk reduced breath isoprene excretion and ML sterol synthesis by 16 ± 5 and 19 ± 4%, respectively. The parallel decreases in isoprene excretion and cholesterol synthesis caused by these pharmacologic and dietary means suggest that breath isoprene is derived from the cholesterol synthesis pathway.
Investigations on the cellular uptake of hexadecylphosphocholine
Authors: Fleer Eduard A. M. , Berkovic Dinko , Eibl Hansjoerg , Unger Clemens 
Published: November 2006

AbstractThe uptake of [(9,10)‐3H]hexadecylphosphocholine (HePC) in six tumor cell lines was studied. All cell lines incorporated HePC in similar amounts, with the exception of the epidermoid cancer cell line KB, which took up higher amounts of HePC. The uptake of HePC at 37°C was shown to be time and concentration dependent. At 20°C, uptake was drastically reduced and at 4°C it was blocked completely. Binding of HePC, at 4°C, was not saturable at concentrations between 5 βg/mL (11.8 μM) and 100 μg/mL (235.3 μM), indicating that cell surface binding is not receptor‐mediated. Furthermore, the effects of inhibitors of endocytosis were investigated. We observed a pronounced inhibitory effect by monensin and cytochalasin B. Colchicine was somewhat less effective whereas chloroquine was almost without effect. From these data we conclude that uptake of HePC is most probably mediatedvia a receptor‐independent endocytotic mechanism.
Fish erythrocytes as a tool to study temperature‐induced responses in plasma membranes
Authors: Dey I. , Szegletes T. , Buda Cs. , Nemcsok J. , Farkas T. 
Published: November 2006

AbstractThe dorsal aorta of carp (Cyprinus carpio L.) was cannulated, and the fish were kept in thermostated aquaria at 5°C for 24h. The water temperature was then gradually increased to 25°C at a rate of 0.5°C/h, and then decreased to 5°C at the same rate. Blood was withdrawn at five‐degree intervals to determine the fluidity of erythrocyte plasma membranes uponex vivo incorporation of the fluorescent dye, 3‐[p‐(6‐phenyl‐1,3,5‐hexatrienyl)phenyl] propionic acid. Steady‐state anisotropy (Rss) of the plasma membranes increased and decreased with the increase and decrease in water temperature, respectively. The sterol‐to‐phospholipid ratio remained unchanged throughout the thermal shifts. The fatty acid compositions of the total phospholipids, of phosphatidylcholine and of phosphatidylethanolamine remained virtually unchanged, except for the level of arachidonic acid, which increased in erythrocytes from fish at the higher temperature (25°C). The molecular species compositions of phosphatidylcholines and phosphatidylethanolamines also remained unaffected throughout the thermal shifts. The erythrocyte plasma membranes were more responsive to temperature shiftsin vivo thanin vitro when percent efficacy was compared. Thus, factors other than lipid changes are conceivably involved in the adaptation of erythrocyte plasma membranes to short‐term thermal changes.
Kinetic study of reactions between tocopheroxyl radicals and fatty acids
Authors: Mukai Kazuo , Morimoto Hitoshi , Okauchi Yuji , Nagaoka Shin‐ichi 
Published: November 2006

AbstractA kinetic study on the prooxidant effect of vitamin E derivatives has been carried out. Rates of hydrogen abstraction from various fatty acids and egg yolk lecithin by tocopheroxyl radicals were determined spectrophotometrically. The rate constants measured in micellar dispersion were compared with those obtained in homogeneous solutions. The effects of structural variations of the vitamin E derivatives on their prooxidant activities were examined. The formation of lecithin reverse micelles in benzene appears to prevent the tocopheroxyl radicals from reacting with the phospholipid fatty acid moieties.
The urinary excretion of thiobarbituric acid reactive substances and malondialdehyde by normal adult males after consuming a diet containing salmon
Authors: Nelson Gary J. , Morris Virginia C. , Schmidt Perla C. , Levander Orville 
Published: November 2006

AbstractIn this study we investigated the output of thiobarbituric acid reactive substances (TBARS) and malondialdehyde (MDA), as thiobarbituric acid (TBA)‐MDA adduct, in the urine from subjects eating a diet in which the only source of n−3 long‐chain, polyunsaturated fatty acids was fresh salmon. Nine healthy men, ages 30–65, were confined in the United States Department of Agriculture Western Human Nutrition Research Center, San Francisco, CA, for 100 d; food intake and exercise levels were controlled. All subjects were placed on a stabilization diet (StD) for 20 d, then six were fed the salmon diet for 40 d. The others remained on the StD. The groups switched diets for the last 40 d. Both diets were isocaloric (16% protein, 54% CHO and 30% fat by energy %). The salmon diet contained 7.5% of calories from n−6 fatty acids (FAs) and 2% from n−3 FAs, primarily eicosapentaenoic acid and docosahexaenoic acid in a 50∶60 ratio, while the StD contained 7.5% from n−6 FAs and <0.3% n−3 FAs (with presumably no significant amounts of C20 or C22 n−3 FAs). Twenty‐four hour urinary output was collected, and 2% 3−d pool samples prepared for analysis of urinary TBARS and the TBA‐MDA adduct. The total urinary output of each individual varied considerably, and on a daily basis the concentration of autoxidation products in an individual's urine varied also. However, the mean daily output (in μmoles TBA‐MDA equivalents/day) at the end of the salmon diet feeding period was significantly greater (7.05±1.33 TBARS,P<0.05; and 7.07±1.73 TBA‐MDA adduct,P<0.01) compared to when the subjects were eating the StD (5.65±1.09 TBARS and 4.65±0.76 TBA‐MDA adduct). When the TBARS and TBA‐MDA adduct values were normalized relative to creatinine output (in nmoles TBA‐MDA equivalents/μmole creatinine), the data achieved even greater statistical significance. The mean output of the group eating the salmon diet was 0.478±0.076 for TBARS (P<0.01) and 0.476±0.082 for the TBA‐MDA adduct (P<0.001)vs. 0.345±0.059 for TBARS and 0.283±0.041 for the TBA‐MDA adduct when the subjects were consuming the StD. Thus, the consumption of cooked fish may increase one's exposure to MDA and other autoxidation products, compounds that may be carcinogenic or mutagenic.
Novel brominated phospholipid fatty acids from the Caribbean spongeAgelas sp.
Authors: Carballeira Néstor M. , Emiliano Anastacio 
Published: November 2006

AbstractThe very long‐chain fatty acids, (5E,9Z)‐6‐bromo‐5,9‐tetracosadienoic, (5E,9Z)‐6‐bromo‐23‐methyl‐5,9‐tetracosadienoic, (5E,9Z)‐6‐bromo‐5,9‐pentacosadienoic and (5E,9Z)‐6‐bromo‐24‐methyl‐5,9‐pentacosadienoic acids, were identified in the phospholipids (mainly phosphatidylethanolamine) of the spongeAgelas sp. Structure elucidation was accomplished by means of mass spectrometry and chemical transformations, including deuteration with Wilkinson's catalyst. All of the sterols from the sponge had the Δ5,7 nucleus, with 24‐methylcholesta‐5,7,22‐trien‐3β‐ol (ergosterol) and 24‐ethylcholesta‐5,7,22‐trien‐3β‐ol being the most abundant.
Identification of two novel dihydroxysterols fromPavlova
Authors: Patterson Gleen W. , Gladu Patricia K. , Wikfors Gary H. , Parish Edward J. , Livant Peter D. , Lusby William R. 
Published: November 2006

AbstractPavlova gyrans andP. lutheri were cultured, and the dihydroxysterols were isolated from the free sterol and the polar sterol fractions. Four dihydroxysterols were detected in amounts greater than 1% of total sterol by gas chromatography and were analyzed by gas chromatography/mass spectrometry. The two principal sterols were isolated by chromatography on alumina followed by hydrophobic Sephadex column chromatography. The two sterols appeared to differ by having either a methyl or an ethyl group at C−24; they were termed “methylpavlovol” and “ethylpavlovol.” Analysis by 400 MHz nuclear magnetic resonance showed that methylpavlovol is 4α,24β‐dimethylcholestan‐3β,4β‐diol and ethylpavlovol is 4α‐methyl,24β‐ethylcholestan‐3β,4β‐diol. The 4α‐methyl,4β‐hydroxy configuration has not been observed previously in a natural sterol. Dihydroxysterols make up approximately one‐third of the total sterols in thesePavlova species. Neither the biosynthetic origin of these dihydroxysterols nor their role in the biochemistry ofPavlova is known.