bluuebunny/crossref_metadata_2025 huggingface dataset:
Substrate specificity of the lipase fromCandida parapsilosis
Authors: Briand Delphine , Dubreucq Eric , Grimaud Jean , Galzy Pierre
Published: November 2006

Substrate specificity of the acyltransferase activity of the lipase (EC 3.1.1.3) fromCandida parapsilosis CBS 604 was studied in aqueous media. The specificity toward both acid and alcohol parts of a large number of acylglycerols and aliphatic esters was investigated. This lipase showed a high activity in the presence of esters with long‐chain fatty acids and particularly unsaturated fatty acids with acis‐Δ9 double bond. It was observed that the activity profile depended not only on the alcohol part of the acyl ester, but also on the temperature of the reactant medium. The best lipid substrates had their melting point between −40 to +20°C, 14 to 18 carbon atoms in the acyl group and 1 to 4 carbon atoms in the alkyl group. The enzyme, defined as an acyltransferase in a previous paper, showed a high affinity for primary and secondary alcohols with a short carbon chain (1 to 5 carbon atoms) as acyl acceptors. The influence of free alcohols in the reactant medium on the hydrolysis and alcoholysis activities of the enzyme is discussed. Two phenomena seem to be involved, depending on the alcohol: competition with water for the acyltransfer reaction and lipid substrate dilution when the alcohol places at the oil/water interface.
Octadecatrienoic acids as the substrates for the key enzymes in glycerolipid biosynthesis and fatty acid oxidation in rat liver
Authors: Ide Takashi , Murata Masakazu , Sugano Michihiro
Published: November 2006

The activities of key enzymes in glycerolipid biosynthesis and fatty acid oxidation were compared using CoA esters of naturally occurring positional isomers of octadecatrienoic acids (18∶3) as the substrates. The trienoic acids employed were 9,12,15–18∶3 (α‐18∶3), 6,9,12–18∶3 (γ‐18∶3), and 5,9,12–18∶3 (pinolenic acid which is a fatty acid contained in pine seed oil, po‐18∶3). The activities of microsomal glycerol 3‐phosphate acyltransferase obtained with various 18∶3 were only slightly lower than or comparable with those obtained with palmitic (16∶0), oleic (18∶1), and linoleic (18∶2) acids. Mitochondrial glycerol 3‐phosphate acyltransferase was exclusively specific for saturated fatty acyl‐CoA. The activities of microsomal diacylglycerol acyltransferase measured with various polyunsaturated fatty acyl‐CoAs were significantly lower than those obtained with 16∶0‐ and 18∶1‐CoAs. Among the polyunsaturated fatty acids, γ‐18∶3 gave the distinctly low activity. The Vmax values of the mitochondrial carnitine palmitoyltransferase I were significantly higher with α‐18∶3 and po‐18∶3 but not γ‐18∶3, than with 16∶0 and 18∶2, while the apparent Km values were the same irrespective of the types of acyl‐CoA used except for the distinctly low value obtained with γ‐18∶3. The response to an inhibitor of the acyltransferase reaction, malonyl‐CoA, was appreciably exaggerated with 18∶2, α‐18∶3, and po‐18∶3 more than with 16∶0 and 18∶1. However, the response with γ‐18∶3 was the same as with 16∶0. Thus, some of glycerolipid biosynthesis and fatty acid oxidation enzymes could discriminate not only the differences in the degree of unsaturation of fatty acids but also the positional distribution of double bond among the naturally occurring 18∶3 acids.
Inhibition of cholesterol esterification in macrophages and vascular smooth muscle foam cells: Evaluation of E5324, an Acyl‐CoA cholesterol acyltransferase inhibitor
Authors: Nicholson Andrew C. , Pomerantz Kenneth B. , Fujimori Tohru , Hajjar David P.
Published: November 2006

Cholesteryl esters (CE) comprise the principal lipid class that accumulates within macrophages and smooth muscle cells of the atherosclerotic lesion. Acyl‐CoA cholesterol acyl‐transferase (ACAT) is the major enzyme responsible for esterification of intracellular cholesterol. We evaluated the ability of E5324 (n‐butyl‐N″‐[‐2‐[3‐(5‐ethyl‐4‐phenyl‐1H‐imidazol‐1‐yl)propoxyl]‐6‐methyl‐phenyllurea), a novel, orally absorbable ACAT inhibitor, to inhibit esterification of fatty acids to cholesterol and CE accumulation in macrophages and in smooth muscle cells. E5324 significantly inhibited cholesterol esterification in rat aortic smooth muscle cells and in macrophages. In addition, E5324 reduced the cellular mass of CE, the significant measure of the efficacy of drugs designed to modulate cholesterol metabolism. E5324 treatment of macrophages exposed to acetylated low‐density lipoprotein reduced CE mass by 97%, and treatment of lipid‐loaded smooth muscle cells reduced CE mass by 29%. Although free cholesterol increased approximately twofold, this free cholesterol would presumably be accessible to the membrane for effluxin vivo (reverse cholesterol transport). These results demonstrate that E5324 can inhibit cholesterol esterification and CE mass in atherosclerotic foam cells, derived from either macrophages or arterial smooth muscle cells.
Synthesis of linoleate and α‐linolenate by chain elongation in the rat
Authors: Cunnane Stephen C. , Ryan Mary Ann , Craig Kerr S. , Brookes Steven , Koletzko Berthold , Demmelmair Hans , Singer Janet , Kyle David J.
Published: November 2006

The objective was to determine whether rats could synthesize longer chain polyunsaturates from hexadecadienoate (16∶2n−6) and hexadecatrienoate (16∶3n−3). Rats were gavaged with uniformly13C‐labelled hexadecadienoate or hexadecatrienoate, euthanized 24 h later, and total lipids were extracted from liver and carcass. Gas chromatogrpahy/combustion/isotope ratio mass spectrometry was used to measure13C levels in individual liver, carcass, and whole body fatty acids.13C Enrichment was present in desaturated and chain‐elongated polyunsaturates, including linoleate, arachidonate, α‐linolenate, and docosahexaenoate at 12–13% of the dose of tracer given.13C Enrichment from hexadecatrienoate was highest in carcass and liver α‐linolenate, representing 3.5 and 17.9% of the total α‐linolenate pool, respectively. For linoleate, arachidonate, or docosahexaenoate, the contribution of13C did not exceed 0.2% of the total body pool. Green leafy vegetables common in the human diet were shown to contain up to 1.2% of total fatty acids as hexadecadienoate and 11.6% as hexadecatrienoate. Hence, humans consuming green vegetables probably synthesize a small proportion of their total body content of linoleate and α‐linolenate.
2,3‐oxidosqualene cyclase: From azasqualenes to new site‐directed inhibitors
Authors: Cattel Luigi , Ceruti Maurizio , Balliano Gianni , Viola Franca , Grosa Giorgio , Rocco Flavio , Brusa Paola
Published: November 2006

2,3‐Oxidosqualene cyclases (OSC) are enzymes which convert 2,3‐oxidosqualene (OS) into polycyclic triterpenoids such as lanosterol, cycloartenol, and α‐and β‐amyrin. Our interest in the study of OSC is the development of new OSC inhibitors for potential use as hypocholesterolemic, antifungal, or phytotoxic drugs. In particular, we describe the biological activity and the mechanism of a series of acyclic azasqualene derivatives mimicking the C‐2, C‐8, and C‐20 carbonium ions formed during OS cyclization. Some of these carbonium ion analogues are very promising as specific hypocholesterolemic agents. The toxicity, the biodistribution, and the pharmacokinetics of different azasqualene derivatives in mice are also presented. In order to obtain new, site‐directed irreversible inhibitors of OSC, a series of squalene derivatives containing functional groups that can link covalently to an active‐site thiol group was designed. Among these compounds, squalene maleimide was the most active toward mammalian OSC, whereas squalene Ellman behaved as an irreversible inhibitor of OSC from yeast
Growth ofCururbita maxima L. plants in the presence of the cycloartenol synthase inhibitor U18666A1
Authors: Fenner Gregeory P. , Raphiou Ibrahim
Published: November 2006

Squash, like other Cucurbitaceae, have unique sterol profiles that offer an excellent opportunity to examine the relationship between sterol biosynthesis and plant growth. To determine the effect of sterol biosynthesis inhibition on squash growth, Cucurbita maxima seedlings with and without cotyledons were subjected to increasing concentrations of the cycloartenol synthase (EC 5.4.99.8) inhibitor 3β‐(2‐diethylaminoethoxy) androstenone (U18666A). Inhibition of shoot growth was concentration‐dependent (from 0, 2, 5, 10, and 20 μM); plants with intact cotyledons grew to 26.4, 23.7, 21.6, 20.0, and 15.6 cm, respectively, at the above inhibitor concentrations, compared to 25.5, 19.4, 17.0, 12.0, and 11 cm for plants with severed cotyledons. In plants with severed cotyledons, 10 and 20 μM U18666A caused rapid necrosis of the first two, newly emerged, primary leaves, and halted new leaf formation. Secondary root formation was initially affected at all inhibitor concentrations regardless of whether cotyledons were present or not. Vegetative tissue showed a decrease in the accumulation of the major squash sterol, 7, 22‐stigmastadienol, accompanied by increased accumulation of minor sterol components. Sterol profiles in cotyledons were unaltered. The data show that sterols are crucial for maintaining plant growth and viability, but do not address the cotyledonary effect on growth with respect to sterol biosynthesis.
Quantitation of steryl ferulate andp‐coumarate esters from corn and rice
Authors: Norton Robert A.
Published: November 2006

The principal steryl ferulate andp‐coumarate esters of different fractions from processed corn brans and corn oils, unrefined and refined, and from rice bran and rice bran oil were quantified by high‐performance liquid chromatography. The results show that hexane‐extracted corn oils yield more than five times the amount of esters compared to expeller processed oils. The yields of esters from bran and related products ranged from 0.07 to 0.54 mg/g of bran. Unrefined corn oils had levels from 0.18 to 8.6 mg/g for oil from hexane‐extracted bran. By comparison, rice bran had ester levels of 3.4 mg/g of bran, and rice bran oil had levels of 15.7 mg/g of oil. The predominant esters from corn were sitostanyl and campestanyl ferulate, and sitostanyl and campestanylp‐coumarate. The principal esters from rice bran were cycloartenyl, 24‐methylenecy‐cloartanyl, and campesteryl ferulate. Rice bran oils had low levels of 24‐methylenecycloartanyl but high levels of cyclobranol esters. The data presented provide a direct comparison of steryl ferulate andp‐coumarate levels in the two cereals, and will aid in selecting the most suitable sources for the isolation of these compounds from corn products.
Mechanism of lysophosphatidylcholine accumulation in the ischemic canine heart
Authors: Mock Thomas , Man Ricky Y. K.
Published: November 2006

The metabolism of lysophosphatidylcholine (LPC) in non‐ischemic and ischemic canine heart was investigated byin vitro enzyme analysis. Selected subcellular fractions were assayed for the LPC‐producing enzyme phospholipase A and the LPC‐eliminating enzymes LPC:acyl‐CoA acyltransferase, LPC:LPC transacylase and lysophospholipase. The canine heart was found to contain all enzymes differing, however, in subcellular distribution and specific activity. Phospholipase A activity did not change significantly in any of the fractions prepared from the ischemic tissue of hearts rendered ischemic for 1, 3 or 5 hr when compared to non‐ischemic tissue. Changes in the activity of the microsomal LPC:acyl‐CoA acyltransferase over the course of 5 hr of ischemia were observed. Significant decreases in the activity of the cytosolic and microsomal lysophospholipases were detected especially after 3 and 5 hr of ischemia. Similarly, a decrease in the activity of the microsomal LPC:LPC transacylase was noted after 3 and 5 hr of ischemia. Our results suggest that impaired catabolism of LPC rather than an enhanced production of LPC is the principal mechanism for the increase in LPC levels in the ischemic canine heart.
Palmitic acid‐labeled lipids selectively incorporated into platelet cytoskeleton during aggregation
Authors: Packham M. A. , Guccione M. A. , Bryant N. L. , Livne A.
Published: November 2006

Previous experiments showed that during the early stages (20–30 seconds) of aggregation induced by adenosine diphosphate (ADP, 2 μM) or thrombin (0.1 U/mL) of rabbit or human platelets prelabeled with [3H]palmitic acid, labeled lipid became associated with the cytoskeleton isolated after lysis with 1% Triton X‐100, 5 mM EGTA [ethylene glycol‐bis‐(β‐aminoethyl ether)]‐N,N,N',N'‐tetra‐acetic acid. The association appeared to be related to the number of sites of contact and was independent of the release of granule contents. We have now investigated the nature of the labeled lipids by thin‐layer and column chromatography and found differences between the distribution of the label in intact platelets (both stimulated and unstimulated) and the isolated cytoskeletons. In both species and with either ADP or thrombin as aggregating agent, 70–85% of the label in both intact platelets and in the cytoskeletons was in phospholipids. The distribution of label among the phospholipids in the cytoskeletons was similar to that in intact platelets except that the percentage of label in phosphatidylcholine was significantly higher in the cytoskeletons of human platelets than in the intact platelets, and the percentage of label in phosphatidylserine/phosphatidylinositol was significantly lower in the cytoskeletons of rabbit platelets and thrombin‐aggregated human platelets than in intact platelets. The cytoskeletons contained a lower percentage of label in triacylglycerol, diacylglycerol, and cholesterol ester than the intact platelets. Contrary to a report in the literature, we found no evidence for the incorporation of diacylglycerol and palmitic acid into the cytoskeleton. Although intact rabbit platelets had more label in ceramide (6.7±2.9%) than intact human platelets (1.5±0.9%), platelets of both species exhibited a three‐ to four‐fold enrichment of labeled ceramide in the cytoskeletons. Thus phospholipids and ceramide that are readily labeled with palmitic acid are selectively incorporated into the cytoskeleton during the initial stages of platelet aggregation.
Effect of excess dietary calcium on colon mucosal membranes and fecal lipids
Authors: Awad Atif B. , Short Mary E. , Fink Carol S.
Published: November 2006

The objective of the present studies was to examine the biochemical alterations in colon apical membranes upon feeding excess calcium to animals on a saturated fatty acid‐rich diet. It has been suggested recently that excess dietary calcium may offer a protection to colon membranes as judged by histologic examination. Sprague‐Dawley weanling male rats were fed a semisynthetic diet containing 14% beef fat plus 2% corn oil and either the calcium requirement or excess calcium in the form of calcium carbonate. Animals were fed the diets for 4 weeks. Feces were collected in the last 3 days. The results indicate that excess dietary calcium resulted in alteration in the density of 4 protein bands of colon apical membranes upon examination on SDS‐gel electrophoresis. These bands contain 20% of membrane proteins. The diet had no effect on either the lipid content or fatty acid composition of the membranes. Excess dietary calcium resulted in 54% reduction in fecal water bile acids and a 44% reduction in fecal water free fatty acids. The reduction in fecal water lipids was due to alterations in the solubility of these lipids. This was not mediated through alterations in the pH of fecal water. The observed alterations in protein patterns of these membranes may be due to either the reduction of fecal water bile acids and free fatty acids or may be a direct effect of dietary calcium on membrane proteins.
Cell separation ofTethya aurantia, an analytical study of embryonic and differentiated sponge cells
Authors: Zimmerman Mary P. , Hoberg Max , Ayanoglu Eser , Djerassi Carl
Published: November 2006

The cells of the spongeTethya aurantia var.californiana were separated on a Ficoll density gradient and the fractions analyzed for cell types and their lipids. Major cell types were choanocyte, archeocyte, and symbiont. Major differences in archeocyte and choanocyte fatty acid composition were noted for 20∶4, 26∶1 and 26∶2. The fatty acids 26∶1, 26∶2, and 28∶3 were dominant in the phosphatidylcholine fraction. Archeocytes had highest concentrations of 4,7,10,13–20∶4 and 5,8,11,14–20∶4 (arachidonic) acids which could be derived from symbionts, as odd‐chain and methyl‐branched fatty acid were also present. Sterol analyses showed cholesterol as a major sterol of the sponge cell fractions and clionasterol (or its 24‐isomer) as a major sterol in symbiont cells.
Structure activity relationships of imidoN‐alkyl semicarbazones, thiosemicarbazones and acethydrazones as hypolipidemic agents in rodents
Authors: Chapman James M. , DeLucy Pierre , Wong Oi T. , Hall Iris H.
Published: November 2006

A series of nitrogen substitutedN‐butan‐3‐one derivatives of cyclic imides (phthalimide, substituted phthalimide,o‐benzosulfimide, 1,8‐naphthalimide, 2,3‐dihydrophthalazine‐1,4‐dione and diphenimide) and their semicarbazone, thiosemicarbazone and acethydrazone derivatives were investigated for hypolipidemic activity in rodents. These compounds were generally potent hypolipidemic agents, lowering serum cholesterol levels on an average of 37% and serum triglyceride levels on an average of 29% after 16 days dosing at 20 mg/kg day intraperitoneally (I.P.) in mice. Several analogs, most notably the semicarbazone and acethydrazone derivatives of 1‐N‐(1,8‐naphthalimido)‐butan‐3‐one, demonstrated improved hypocholesterolemic activity relative to their ketone percursors. Similarly, the acethydrazone derivatives generally resulted in improved hypotriglyceridemic activity in each series of 2‐(3‐oxobutyl)‐2,3‐dihydrophthalazone‐1,4‐dione analogs tested. The thiosemicarbazones in mice generally resulted in a loss in hypolipidemic activity. Select compounds, 1‐N‐3‐methylphthalimido butan‐3‐semicarbazone (Ig) and 1‐(4‐methoxyphthalazine‐1(2H)‐one)yl butan‐3(N‐acetyl)hydrazone (IVg), at 10 mg/kg/day orally administered to rats demonstrated potent hypolipidemic activity after 14 days. These compounds lowered liver, small intestine mucosa and aorta wall tissue lipids, e.g. cholesterol and triglycerides, and raised fecal excretion of cholesterol moderately and of triglyceride significantly. Rat serum lipoprotein fractions after treatment for 14 days showed that the two agents lowered VLDL cholesterol and raised HDL cholesterol content.
Separation and detection of phospholipid hydroperoxides in the low nanomolar range by a high performance liquid chromatography/irothiocyanate assay
Authors: Mullertz Anette , Schmedes Anne , Hølmer Gunhild
Published: November 2006

A new method for the detection of phospholipid hydroperoxides in the low nanomolar range has been developed by using a high performance liquid chromatography system combined with a post‐column reaction. The detection is based on the oxidation of Fe(II) to Fe(III) by hydroperoxides and the subsequent formation of an ironthiocyanate complex, which can be determined spectrophotometrically at 505 nm. By this method it is possible to separate and quantitate phosphatidylethanolamine hydroperoxide and phosphatidylcholine hydroperoxide formed in erythrocyte ghost membranes during photo‐oxidation.
Hydrolysis of fluorescent pyrene‐acyl esters by human pancreatic carboxylic ester hydrolase and bile salt‐stimulated lipase
Authors: Negre‐Salvayre Anne , Abouakil Nehza , Lombardo Dominique , Salvayre Robert
Published: November 2006

Fluorescent esters containing pyrenedecanoic acid (P10) or pyrenebutanoic (P4) acid (P4cholesterol, P10cholesterol, P4‐ and P10‐containing triacylglycerols) were synthesized and used as substrates for human pancreatic carboxylic ester hydrolase and bile salt‐stimulated lipase from human milk. Both enzymes were purified by immunoaffinity chromatography. All fluorescent pyrene derivatives were hydrolyzed by pancreatic carboxylic ester hydrolase and bile salt‐stimulated lipase, but at different rates. The hydrolytic rates of the “short” acyl esters (P4‐containing esters) were higher than those of the “long” ones (P10‐containing esters). Conditions were optimized for sensitivity of the assay using fluorescent cholesteryl esters. The pH optimum was 7.5–8.0. Sodium cholate exhibited a stronger activating effect than taurocholate or taurodeoxycholate (maximal activation was achieved with 5 mmol/L cholate and with a molar ratio cholesteryl ester/cholate around 1∶10). Both pancreatic carboxylic ester hydrolase and bile salt‐stimulated lipase from milk were strongly inhibited by the other amphiphiles tested, namely phosphatidylcholine and Triton X‐100, and were inactivated by low concentrations (10 μmol/L) of the serine‐reactive diethyl‐paranitrophenyl phosphate (E600). Both enzymes were strongly inhibited by relatively low concentrations of plasma low density lipoproteins. These studies indicate that the fluorescent esters containing pyrene fatty acids can be used as substrates for assaying and investigating the properties of pancreatic carboxylic ester hydrolase as well as bile salt‐stimulated lipase from milk.
Gas chromatographic analysis of reactive carbonyl compounds formed from lipids upon UV‐irradiation
Authors: Dennis K. J. , Shibamoto T.
Published: November 2006

Peroxidation of lipids produces carbonyl compounds; some of these, e.g., malonaldehyde and 4‐hydroxynonenal, are genotoxic because of their reactivity with biological nucleophiles. Analysis of the reactive carbonyl compounds is often difficult. The methylhydrazine method developed for malonaldehyde analysis was applied to simultaneously measure the products formed from linoleic acid, linolenic acid, arachidonic acid, and squalene upon ultraviolet‐irradiation (UV‐irradiation). The photoreaction products, saturated monocarbonyl, α,β‐unsaturated carbonyls, and β‐dicarbonyls, were derivatized with methylhydrazine to give hydrazones, pyrazolines, and pyrazoles, respectively. The derivatives were analyzed by gas chromatography and gas chromatography‐mass spectrometry. Lipid peroxidation products identified included formaldehyde, acetaldehyde, acrolein, malonaldehyde, n‐hexanal, and 4‐hydroxy‐2‐nonenal. Malonaldehyde levels formed upon 4 hr of irradiation were 0.06 μg/mg from squalene, 2.4 μg/mg from linolenic acid, and 5.7 μg/mg from arachidonic acid. Significant levels of acrolein (2.5 μg/mg) and 4‐hydroxy‐2‐nonenal (0.17 μg/mg) were also produced from arachidonic acid upon 4 hr irradiation.
Dietary linoleic acid and polyunsaturated fatty acids in rat brain and other organs. Minimal requirements of linoleic acid
Authors: Bourre J. M. , Piciotti M. , Dumont O. , Pascal G. , Durand G.
Published: November 2006

Starting three weeks before mating, 12 groups of female rats were fed different amounts of linoleic acid (18∶2n−6). Their male pups were killed when 21‐days‐old. Varying the dietary 18∶2n−6 content between 150 and 6200 mg/100 g food intake had the following results. Linoleic acid levels remained very low in brain, myelin, synaptosomes, and retina. In contrast, 18∶2n−6 levels increased in sciatic nerve. In heart, linoleic acid levels were high, but were not related to dietary linoleic acid intake. Levels of 18∶2n−6 were significantly increased in liver, lung, kidney, and testicle and were even higher in muscle and adipose tissue. On the other hand, in heart a constant amount of 18∶2n−6 was found at a low level of dietary 18∶2n−6. Constant levels of arachidonic acid (20∶4n−6) were reached at 150 mg/100 g diet in all nerve structures, and at 300 mg/100g diet in testicle and muscle, at 800 mg/100 g diet in kidney, and at 1200 mg/100 g diet in liver, lung, and heart. Constant adrenic acid (22∶4n−6) levels were obtained at 150, 900, and 1200 mg/100 g diet in myelin, sciatic nerve, and brain, respectively. Minimal levels were difficult to determine. In all fractions examined accumulation of docosapentaenoic acid (22∶5n−6) was the most direct and specific consequence of increasing amounts of dietary 18∶2n−6. Tissue eicosapentaenoic acid (20∶5n−3) and 22∶5n−3 levels were relatively independent of dietary 18∶2n−6 intake, except in lung, liver, and kidney. In several organs (muscle, lung, kidney, liver, heart) as well as in myelin, very low levels of dietary linoleic acid led to an increase in 20∶5n−3. Dietary requirements for 18∶2n−6 varied from 150 to 1200 mg/100 g food intake, depending on the organ and the nature of the tissue fatty acid. Therefore, the minimum dietary requirement is estimated to be about 1200 mg/100 g (i.e., the level that ensures stable and constant amounts of arachidonic acid).
The response to endotoxin in guinea pigs after intravenous black currant seed oil
Authors: Hirschberg Yulia , Shackelford Alan , Mascioli Edward A. , Babayan Vigen K. , Bistrian Bruce R. , Blackburn George L.
Published: November 2006

The influence on the metabolic response to endotoxin of three days of total parenteral nutrition with lipids high in gammalinolenic acid (18∶3ω6, GLA) compared to soy oil (SO) was examined in acute operatively stressed guinea pigs. GLA is the precursor of dihomogammalinolenic acid (DHLA), the substrate for synthesis of “1” series prostaglandins such as PGE1, which have previously been shown to be protective in endotoxin lung injury and traumatic shock. Guinea pigs fed an intravenous diet containing black currant seed oil (BCO) emulsion (20% GLA) or soy oil emulsion (0% GLA) for 2.5 days had their arterial pH, pCO2, pO2, and bicarbonate measured at baseline and hourly during a 7‐hr infusion of endotoxin (lipopolysaccharide (LPS), 2mg/kg) or saline. Plasma lactate and fatty acid profile analyses were performed at the end of the LPS infusion. Increased levels of GLA and DHLA were present in the plasma phospholipid fraction of animals fed the black currant seed oil diet, while soyfed animals had only trace amounts of GLA. In addition, the ratio of DHLA to arachidonate was higher in animals receiving the black currant seed oil total parenteral nutrition (TPN). After 2 hr of LPS infusion, all animals exhibited the typical shock response resulting in metabolic acidosis characterized by a significant (p<0.05) drop in pH from 7.34±.02 (SO) and 7.39±.02 (BCO) at baseline to 7.14±.05 and 7.22±.04 by 7 hr for SO and BCO groups, respectively. Plasma lactate values at the end of the infusion were significantly elevated compared to saline in both groups (p<0.05). Guinea pigs fed GLA showed no improvement over soy‐fed animals, and actually exhibited a more pronounced metabolic acidosis and increased mortality (50% vs 0%) over the 7 hr of LPS infusion. No beneficial effects of a diet high in GLA were observed in the present study.
Uptake, incorporation and metabolism of (3H)triolein in the isolated perfused rabbit heart
Authors: Weis Margaret T. , Palazzo Anthony J. , Williams J. Lynn , Malik Kafait U.
Published: November 2006

The purpose of these experiments was to study the uptake and metabolism of exogenous triglyceride in the isolated perfused rabbit heart. When infused into the rabbit heart, [9,10‐3H(N)]triolein was retained and incorporated into a lipid fraction that had the chromatographic mobility of authentic triolein. Incorporation of labeled triolein was not likely to be the result of a lipoprotein lipase‐mediated lipolysis/resynthesis cycle, since: (i) The distribution of radioactivity following administration of [3H]oleic acid was markedly different from the distribution of radioactivity following the administration of [3H]triolein; (ii) heparin was administered to the rabbits at the time of sacrifice; and (iii) the hearts were perfused with a protein‐free buffer for 20 min prior to the labelling period. When isoproterenol was administered to hearts labelled with [3H]triolein, there was an increased output of total radioactivity, composed of labelled free fatty acids, diacylglycerol and monoacylglycerol. In these same hearts, there was an increased output of glycerol in response to isoproterenol. However, following the administration of bradykinin or angiotensin II, neither the radioactivity nor the glycerol content of the perfusate was changed. These data suggest that [3H]triolein is selectively incorporated into the triglyceride pool of the isolated perfused rabbit heart. Furthermore, this [3H]triolein is available to hormonally‐activated lipolytic enzymes.
Hepoxilins: A review on their enzymatic formation, metabolism and chemical synthesis
Authors: Pace‐Asciak C. R. , Reynaud Denis , Demin Peter M.
Published: November 2006

This article reviews published evidence describing the enzymatic and nonenzymatic formation and the routes of metabolism of the hepoxilins. Also treated are the major approaches used for the chemical synthesis of these compounds and for some of their analogs.
Phase properties of mixtures of ceramides
Authors: Han Chien‐Hsuan , Sanftleben Ronald , Wiedmann Timothy S.
Published: November 2006

Ceramides have been proposed to have a central role in the function of the stratum corneum. Ceramides also influence the phase properties of model skin lipid mixtures, but the relevance of this to the stratum corneum function is controversial. Because the stratum corneum contains several classes of ceramides, the type of ceramides used in model mixtures of stratum corneum lipid lamellae may be important. Thus, the properties of α‐hydroxy fatty acid containing (HFAC) and nonhydroxy fatty acid containing (NFAC) ceramides and their mixtures have been investigated. Ceramides were obtained by the conversion of purified bovine brain cerebrosides. Isolated, anhydrous HFAC underwent an endothermic solid to liquid transition at 92°C. With hydration, an endothermic transition at 71.8°C was observed which was accompanied by a reduction in the birefringence. The enthalpy increased from 66 to 89 J/g with a 20‐d storage time. These thermal properties are very similar to those observed with hydroxy fatty acid containing cerebrosides. In contrast, anhydrous nonhydroxy fatty acid containing ceramides underwent a broad endothermic transition over the temperature range of 50–90°C. When hydrated, the initial endothermic transition was interrupted by an exothermic transition that was followed immediately by a second endothermic transition. During these thermal changes, there was a loss of birefringence, and with completion of the second endothermic transition, a nonbirefringent liquid was observed. NFAC samples, stored at 70°C for 5 min, cooled, and then rescanned, displayed only one endotherm at 75°C. The thermal behavior of mixtures of HFAC and NFAC was relatively simple, with a progressive decrease and broadening in the temperature of the phase transition as the proportion of NFAC increased up to weight fractions of NFAC of 0.7. At lower weight fractions, a plateau in thetransition temperature as a function of weight fraction was observed. Even at a weight fraction of 0.1 HFAC, no transition to a nonbirefringent liquid state was observed. The high enthalpic changes observed with mixtures of HFAC and NFAC are consistent with the proposed central role that ceramides have in the mechanical and permeability properties of the skin. Moreover, the marked difference in the properties of these two similar lipids may help to explain some of the properties of the stratum corneum.
Effect of exercise on the plasma nonesterified fatty acid composition of dogs and goats: Species with different aerobic capacities and diets
Authors: McClelland Grant , Zwingelstein Georges , Taylor C. Richard , Weber Jean‐Michel
Published: November 2006

The goals of this study were to determine: (i) whether mammals mobilize particular nonesterified fatty acids (NEFA) preferentially during locomotion, (ii) if differences in aerobic capacity or diet can affect the pattern of NEFA mobilization and (iii) which individual NEFA are most representative of total NEFA concentration changes, to use them as tracers for turnover studies. Individual NEFA were measured in trained dogs and goats (VO2max dog/VO2max goat=2.2; where VO2max=max‐imal oxygen consumption) during treadmill exercise at 40 and 60% VO2max. Important interspecies differences in individual NEFA concentrations could be attributed to differences in aerobic capacity. The more aerobic species (dog) had much higher plasma NEFA concentrations for all but one NEFA (18∶0), when compared with the low‐aerobic species (goat). In addition, exercise caused a large increase in concentration of individual NEFA in the dogs, with the largest increases seen in 18∶1 (150% above resting values) and 16∶0 (60% increase), but it had no effect in goats. Therefore, the aerobic species has a much higher ability for mobilizing and transporting NEFA in plasma than its low‐aerobic counterpart. Two NEFA accounted for more than half total plasma NEFA in both species, 18∶1 (about 35% total NEFA) and 16∶0 (20%). Calculation of variability in percent composition reveals that oleate and palmitate also closely reflect changes in total NEFA and are therefore the most appropriate tracers forin vivo kinetic studies in exercising mammals. Differences in diet and digestion physiology explained some differences in the plasma NEFA composition of the two species; this was reflected in the percent contributions of individual fatty acids to total NEFA: in dogs 18∶1>16∶0>18∶2>18∶0, while in goats 18∶1>16∶0>18∶0>18∶2. Also, only goats had 18∶3 (6% total NEFA), a fatty acid of plant origin, while only dogs had 16∶1 (7% total NEFA). Overall, however, the plasma NEFA composition of goats did not exactly reflect that of their diet due to preabsorptive modification of unsaturated fatty acids, while in dogs there was a good correlation between dietary and plasma NEFA.
Dietary oligofructose lowers triglycerides, phospholipids and cholesterol in serum and very low density lipoproteins of rats
Authors: Fiordaliso Maria , Kok Nadine , Desager Jean‐Pierre , Goethals Fabienne , Deboyser Dominique , Roberfroid Marcel , Delzenne Nathalie
Published: November 2006

The present study was aimed at answering the question why feeding rats an oligofructose (OFS) supplemented diet could cause a significant reduction in plasma lipid levels. Daily administration of a 10% (w/w) OFS‐containing diet to normolipidemic male rats resulted in a decrease in plasma triglycerides, phospholipids and cholesterol. The triglyceride‐lowering effect was observed after one week and lasted for at least 16 wk and was associated with a reduction in plasma very low density lipoproteins, indicating that the hypolipidemic effect of OFS may be due to changes in liver lipid metabolism. We therefore tested whether OFS feeding modified the capacity of the liver to synthesize triglycerides from free fatty acids. Hepatocytes isolated from livers of control and OFS‐fed rats were incubated in the presence of [1‐14C]palmitate, and both intracellular and extracellular [14C]triglyceride formation were quantified. We found that chronic feeding of an OFS‐supplemented diet to rats significantly reduced the capacity of isolated hepatocytes to synthesize triglycerides from palmitate. The results suggest that, like other soluble dietary fibers, OFS significantly alters liver lipid metabolism, resulting over time in a significant reduction in plasma triglyceride, phospholipid and cholesterol levels.
Incorporation ofall‐trans‐or 9‐cis‐β‐carotene into mixed micellesin vitro
Authors: Levin Galit , Mokady Shoshana
Published: November 2006

Various studies suggest thatall‐trans‐ and 9‐cis‐β‐carotene are absorbed in the intestine to different extents. The present study was undertaken to evaluate the degree ofin vitro incorporation of the two isomers into intestinal mixed micelles, which is an essential early step in the absorption process. The micelles were designed to simulate those present during fat digestion in the lumen of the human small intestine with respect to bile salts, lipids, pH and temperature. Solutions ofall‐trans‐and 9‐cis‐β‐carotene at various ratios were added to the lipid mixture. A direct correlation was seen between the 9‐cis‐β‐carotene level in the mixture and the degree of total β‐carotene incorporation into micelles. An increased level ofall‐trans‐β‐carotene incorporated into the micelles. In contrast, when carotene mixtures enriched with the 9‐cis isomer were used, an increase in the level of total carotene in the solution was accompanied by a constant or even enhanced carotene incorporation. The results indicate that the differences in the absorption of β‐carotene isomers might be the result of their different ability to be incorporated into the lipid micelles of the intestinal lumen. In addition, the results point toward the possibility that ingestion of 9‐cis‐β‐carotene by humans may increase carotene availability.
Comparison of fatty acid α‐oxidation by rat hepatocytes and by liver microsomes fortified with NADPH, Fe3+ and phosphate
Authors: Huang Shewen , Van Veldhoven Paul P. , Asselberghs Stanny , Eyssen Hendrik J. , de Hoffmann Edmond , Mannaerts Guy P.
Published: November 2006

Rat liver microsomes, when fortified with NADPH, Fe3+ and phosphate, can catalyze the oxidative decarboxylation (α‐oxidation) of 3‐methyl‐substituted fatty acids (phytanic and 3‐methylheptadecanoic acids) at rates that equal 60–70% of those observed in isolated hepatocytes (Huang, S., Van Veldhoven, P.P., Vanhoutte, F., Parmentier, G., Eyssen, H.J., and Mannaerts, G.P., 1992,Arch. Biochem. Biophys. 296, 214–223). In the present study we set out to identify and compare the products and possible intermediates of α‐oxidation formed in rat hepatocytes and by rat liver microsomes. In the presence of NADPH, Fe3+ and phosphate, microsomes decarboxylated not only 3‐methyl fatty acids but also 2‐methyl fatty acids and even straight chain fatty acids. The decarboxylation products of 3‐methylheptadecanoic and palmitic acids were purified by highperformance liquid chromatography and identified by gas chromatography/mass spectrometry as 2‐methyl‐hexadecanoic and pentadecanoic acids, respectively. Inclusion in the incubation mixtures of glutathione plus glutathione peroxidase inhibited decarboxylation by more than 90%, suggesting that a 2‐hydroperoxy fatty acid is formed as a possible intermediate. However, we have not yet been able to unequivocally identify this intermediate. Instead, several possible rearrangement metabolites were identified. In isolated rat hepatocytes incubated with 3‐methylheptadecanoic acid, the formation of the decarboxylation product, 2‐methylhexadecanoic acid, was demonstrated, but no accumulation of putative intermediates or rearrangement products was observed. Our data do not allow us to draw conclusions on whether the reconstituted microsomal system is representative of the cellular α‐oxidation system. However, the results we obtained with [3‐3H]‐labelled fatty acids indicate that during α‐oxidation in intact cells the hydrogen at carbon‐3, which carries the methyl branch, is not attacked.
Lipid composition of glucose‐stimulated pancreatic islets and insulin‐secreting tumor cells
Authors: Rustenbeck Ingo , Matthies Alexander , Lenzen Sigurd
Published: November 2006

The effect of glucose stimulation (25 mM for 5 min) on the phospholipid and neutral lipid composition of isolated pancreatic islets was studied to find out whether there is a change in the mass of potential lipid mediators or modulators of insulin secretion. For comparison, the lipid compositions of homogenates and subcellular fractions from RINm5F insulin‐secreting tumor cells and of glucose‐stimulated streptozotocin/nicotinamide‐induced islet cell tumors were analyzed. After separation of the lipid extract into a neutral and an acidic fraction by anion‐exchange chromatography, lipids were separated by high‐performance thin‐layer chromatography and quantitated byin situ densitometry of the cupric sulfate‐charred bands. In glucose‐stimulated islets, the molar percentages of phosphatidic acid (PA) and of phosphatidylinositol were significantly increased (3.1 vs. 4.7 mol% and 8.6 vs. 11.8 mol%), while those of all other phospholipids and neutral lipids, including 1,2‐diacylglycerol, were not significantly changed. In stimulated islet cell tumors, an increase of PA was visible in the microsomal fraction, and there was an increase of lysophosphatidylcholine in the mitochondrial fraction. However, in both tumoral tissues, particularly in RINm5F cells, the lipid distribution pattern showed abnormalities which can be regarded as a loss of differentiation and which limit the usefulness of these tissues for the study of the physiological regulation of lipid metabolism during glucose stimulation. In conclusion, the data are in accordance with a role of PA early in stimulus‐secretion coupling. The well‐known stimulation of phospholipid synthesis in pancreatic islets during glucose‐induced insulin secretion does not result in an increase in the total phospholipid mass.
Effect of dietary fat on colonic protein kinase C and induction of aberrant crypt foci
Authors: Lafave Lynne M. Z. , Kumarathasan Prem , Bird Ranjana P.
Published: November 2006

A major objective of the present study was to determine whether a high‐fat diet affects early events during colon carcinogenesis. Female Sprague‐Dawley rats were injected with saline or azoxymethane (20 mg/kg) and fed either a normal (5% corn oil w/w) or a high (5% corn oil and 15% beef tallow w/w) fat diet. To assess the effect of a known tumor‐promoting diet on the early events of neoplastic transformation, Study 1 examined the induction and growth of aberrant crypt foci (ACF) as well as of proliferative indices. The total number of ACF were similar in both groups even after 8 wk of dietary treatment; however, ACF with accelerated growth characteristics (≥4 crypts/focal lesions) were more prevalent (P≤0.05) in the colons of animals fed the high‐fat diet. Metaphase arrest cells and 5′‐bromo‐2′‐deoxyuridine labelled cells showed no appreciable response to dietary changes. To determine whether changes in colonic signal transduction pathways represent an early response to dietary modification, Study 2 evaluated the activity of protein kinase C (PKC), proliferative indices and changes in phospholipid fatty acid profiles. In comparison to the normal fat group, the colons of high‐fat fed animals exhibited higher (P≤0.05) membranes and lower soluble PKC activity; however, proliferation patterns of these colons were not altered. Changes in the membrane lipid composition were minor; however, an increase in the phosphatidylcholine/phosphatidylethanolamine ratio and in 20∶4n−6 was noted. Our results demonstrate that in comparison to a normal‐fat diet, a high‐fat diet stimulated the growth of a population of ACF, i.e., preneoplastic lesions leading to advanced growth characteristics. In addition, a high‐fat diet exerted a marked influence on total, cytosolic and membrane associated PKC activities. The findings suggest that modulation of PKC may play a critical role at the early stages of colon carcinogenesis.
Apolipoprotein A‐I, A‐IV and E synthesis in the liver of copper‐deficient rats
Authors: Nassir Fatiha , Mazur Andrzej , Gueux Elyett , Sérougne Colette , Rayssiguier Yves
Published: November 2006

Copper deficiency induces hypercholesterolemia in the rat. This hypercholesterolemia is mainly due to an increase in apo E‐rich high density lipoproteins (HDL1). The present study was undertaken to determine whether the HDL increase could be explained by altered low‐molecular weight apolipoprotein (apo) synthesis in the liver. The effect of copper deficiency on apo A‐I, apo A‐IV and apo E concentrations in plasma, as well as on respective mRNA levels and synthesis in the liver, were therefore investigated. We observed that the increased HDL1 levels in the plasma of copper‐deficient rats were associated with a significant rise in plasma apo E concentrations; however, plasma apo A‐I and apo A‐IV concentrations remained unchanged. Liver apo synthesis and respective apo mRNA levels were not significantly altered in copper‐deficient animals when compared to control rats. No changes in apo E mRNA levels in various tissues from copper‐deficient, as compared to control rats, were noted. Based on the data obtained, it was concluded that the observed changes in plasma lipoprotein and apo concentrations are not related to changes in low‐molecular weight apo synthesis in the liver. The mechanisms of the impaired catabolism of HDL1 should be further evaluated to possibly explain the observed increase in this fraction in copper‐deficient rats.
Recommendations for the use of species diversity indices with reference to a recently published article as an example
Authors: Itô Yosiaki
Published: November 2006

There are some recommendations for the use of species diversity indices in a paper recently published in this journal by M. Ohsawa on the species richness and composition of weevils in five forest types in the middle region of Japan. Because several factors, such as small sample size, calculation of Simpson's diversity index by the use of the original equation of Simpson's measure of concentration D, and a weak point in the Shannon–Wiener diversity index H′, may have led to biased estimates, I recalculated these indices using combined species diversity values of the five forest types. As the general tendencies of 1−D and H′ values calculated here were similar to those in Ohsawa's paper, there is no need to propose any change to his view. However, these recalculated diversity indices indicated that they are values which are more suitable for use. It should be noted that the characteristics and weak point associated with the diversity indices need to be taken into account in future studies.
Thermal decomposition as route for silver nanoparticles
Authors: Navaladian S. , Viswanathan B. , Viswanath R. P. , Varadarajan T. K.
Published: November 2006

Single crystalline silver nanoparticles have been synthesized by thermal decomposition of silver oxalate in water and in ethylene glycol. Polyvinyl alcohol (PVA) was employed as a capping agent. The particles were spherical in shape with size below 10 nm. The chemical reduction of silver oxalate by PVA was also observed. Increase of the polymer concentration led to a decrease in the size of Ag particles. Ag nanoparticle was not formed in the absence of PVA. Antibacterial activity of the Ag colloid was studied by disc diffusion method.
Discriminating power of the hydrocarbon content from virgin olive oil of extremadura cultivars
Authors: Bueno Emilio Osorio , Casas Jacinto Sánchez , García Alfonso Montaño , González Lourdes Gallardo
Published: November 2006

Samples of virgin olive oils (105) from seven Extremaduran olive varieties (Cacereña, Carrasqueña, Cornezuelo, Corniche, Morisca, Picual, and Verdial de Badajoz) in three stage of maturity (green, semi‐ripe, and ripe) were collected and the alkane, alkene, and sesquiterpene contents determined. There were significant differences at the 0.01 probability level in most of the hydrocarbons, both by variety and by state of maturity. Discriminant analysis applied to 70 samples explained 72.3% of the variance between the different groups of varieties and allowed 90% of the samples to be classified according to their variety. The acceptability of the model was verified against the remaining 35 samples, giving a mean level of correct classification of 94%.