bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxygen and carbon source‐regulated expression of PDC and ADH genes in the respiratory yeast Pichia anomala
Authors: Fredlund Elisabeth , Beerlage Christiane , Melin Petter , Schnürer Johan , Passoth Volkmar
Published: November 2006

We amplified, sequenced and studied the transcriptional regulation of genes of the alcoholic fermentation pathway in the biocontrol and non‐Saccharomyces wine yeast, Pichia anomala. Two ADH isogenes, PaADH1 and PaADH2, and one PDC gene, PaPDC1, were amplified from genomic P. anomala DNA by a two‐step PCR approach, using degenerated primers against conserved regions of the respective genes for cloning core regions, and PCR‐based gene walking for cloning the respective 5′ and 3′‐ends. According to sequence analysis, ADH1 and PDC1 are most likely cytoplasmatic proteins, while ADH2 is most probably localized in the mitochondria. PaADH1 was expressed during aerobic growth on glucose, ethanol and succinate, but was nine‐fold upregulated in response to oxygen limitation when grown on glucose. The gene seems to be involved in both production and consumption of ethanol. Only low expression of PaADH2 was detected during growth on glucose and ethanol, but it was highly expressed during growth on the non‐fermentable carbon source succinate and repressed by the addition of glucose. PaPDC1 was expressed during aerobic growth on glucose and was upregulated four‐fold in response to oxygen limitation. PaPDC1 expression was lower in cells grown on ethanol and succinate than on glucose and was up‐ regulated two‐ and four‐fold, respectively, after glucose addition. Our results demonstrate that transcription of genes of the fermentative pathway is regulated by hypoxia and carbon source but posttranscriptional regulation may play a major role in regulating the metabolic flux. Copyright © 2006 John Wiley & Sons, Ltd.
Lipids of dermatophytes II. Effect of growth condition on the lipid composition and membrane transport ofMicrosporum gypseum
Authors: Larroya Saroj , Khuller Gopal K.
Published: November 2006

Supplementation of glucose‐containing medium with ethanol and replacement of glucose by glycerol in the Sabouraud’s growth medium ofMicrosporum gypseum altered the levels of total phospholipids as well as their apolar and polar head groups. The levels of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) increased under these growth conditions; also, the ratio of unsaturated/saturated phospholipid fatty acids decreased on ethanol supplementation but increased in the presence of glycerol. Steady state accumulation of labelled amino acids (glycine, lysine and aspartic acid) was affected under these conditions.
Incorporation oftrans fatty acids into submandibular salivary gland lipids
Authors: Alam Syed Q. , Alam Bassima S. , Banerji Arnold
Published: November 2006

Three groups of rats were fed diets containing 20% corn oil, 20% margarine stock (MS) or 19% MS +1% corn oil. Diets were fed for 12 weeks, 1 week of pregnancy, 3 weeks of lactation and 8 weeks post‐weaning. The incorporation oftrans‐octadecenoate into various lipids of the submandibular salivary gland (SMSG) homogenates and plasma membranes was studied.Trans octadecenoate was incorporated into all the lipid fractions studied. Its levels were the highest in phosphatidylethanolamine. The double bond index of phospholipid fatty acids in the plasma membranes of the SMSG was substantially lower in the group fed 20% MS. The fluorescence polarization of 1,6‐diphenyl‐1,3,5‐hexatriene (DPH) was generally higher in the membranes of SMSG from rats fed MS than that of the other two groups, thus indicating lower fluidity. Also, the breakpoints in fluorescence polarization were at a higher temperature in the membranes from rats fed MS as compared with those fed corn oil. Lower fluidity of plasma membranes of SMSG observed in rats fed 20% MS may result in modification of the activities of membrane‐bound enzymes.
A mild, rapid, and efficient method of lipid extraction for use in determining vitamin E/lipid ratios
Authors: Burton Graham W. , Webb Ann , Ingold Keith U.
Published: November 2006

A new, general method for lipid extraction and measurement of vitamin E/total lipid ratios in tissue and cell samples has been developed. The new extraction procedure use a combination of sodium dodecylsulfate, ethanol andn‐heptane, and is mild, clean, convenient, efficient and rapid (≤5 min). The efficiency of the new method has been confirmed for human plasma, red blood cells and rat liver homogenate by the comparison of the yields of vitamin E, O‐acyl lipid and cholesterol with the yields obtained following conventional extraction procedures. Extraction efficiency also has been confirmed for multilamenllar vesicles composed of known quantities of vitamin E, egg lecithin and cholesterol.
Rapid and convenient separation of phospholipids and non phosphorus lipids from rat heart using silica cartridges
Authors: Juaneda Pierre , Rocquelin Gerard
Published: November 2006

The separation of non phosphorus lipids and phospholipids of rat heart using Sep‐pack Silica cartridges is described. No cartridge preparation is necessary before utilization. The separation of lipid extracts is very fast. A complete partition of non phosphorus lipids and phospholipid is obtained.
A colorimetric assay of pancreatic lipase: Rapid detection of lipase and colipase separated by gel filtration
Authors: Roberts Johnna , Stella Valentino J. , Decedue Charles J.
Published: November 2006

A rapid assay for pancreatic lipase (E.C., glycerol‐ester hydrolase 3.1.1.3) is described. The assay is based on the color change of a pH indicator as butyric acid is released from the substrate tributyrin. A mixture made with tributyrin and the water soluble components of the assay is ideally suited for use as a rapid test as, for example, when assaying chromatography fractions. Quantitative data can be obtained by measuring the disappearance of absorbance at 557 nm versus a blank reaction. The assay has been used in the rapid preparation of colipase‐free lipase and colipase.
Effect of type of diet and feeding status on modulation of hepatic HMG‐CoA reductase in rats
Authors: Kelley Michael J. , Story Jon A.
Published: November 2006

The effect of diet type and feeding status on hepatic HMG‐CoA reductase (HMGR) [mevalonate: NADP+ oxidoreductase (acylating CoA); EC 1.1.1.34] was studied in rats. Animals fed a ground, commercial, stock diet exhibited higher expressed and total activities of HMGR in the fed state than animals fed a semi‐purified diet. The differences did not appear in meal‐trained animals when measured before the onset of the meal after a 22‐hr fast. When expressed activity was taken as a per cent of total activity, fed animals from both diet groups used about 10% of their available activity. When animals on commercial diets were fasted, 20% of the activity was expressed. Fasted animals on the semi‐purified diet also increased the per cent of expressed reductase activity, but this increase was not as great (13.3%).

These data suggest that, in the rat, regulation of cholesterol synthesis in response to decreased total HMGR during fasting and increased levels after a meal results from alterations in the percentage of enzyme which is expressed. The semi‐purified diet used here resulted in consistently lower levels of HMG‐CoA reductase activity than the commercial diet regardless of feeding pattern.
Distribution of glycosphingolipids of monkey small and large intestinal mucosa
Authors: Dahiya Rajvir , Brown Michael D. , Brasitus Thomas A.
Published: November 2006

The ganglioside and neutral glycosphingolipid composition of adult monkey small and large intestinal mucosa were characterized and compared. GM3, GM2 and GD1A were found to be the principal gangliosides in each of these tissues. Dihexosylceramide was the major neutral glycosphingolipid of both organs. The total content of gangliosides and neutral glycolipids/ceramide, however, was ca. four‐fold and two‐fold higher, respectively, in small intestinal than colonic mucosa.

While all glycosphingolipids examined contained hydroxy and nonhydroxy fatty acids, the former fatty acids accounted for 60–90% of the total fatty acids in both organs. Sphingosine was the predominant long chain base of ceramide, mono‐, di‐, tri‐ and tetrahexosylceramide, whereas phytosphingosine was the major base of GM3 in both tissues. The results of these studies demonstrate that while many similarities of monkey small and large intestinal glycosphingolipids exist, qualitative and quantitative differences are present along the length of the monkey gut. These differences may be at least partially responsible for certain of the well‐recognized variations in normal physiological and pathological processes that occur in these organs.
Distribution of glycosphingolipids and ceramide of rat small intestinal mucosa
Authors: Dahiya Rajvir , Brasitus Thomas A.
Published: November 2006

Previous studies have suggested that glycosphingolipids may be involved in a number of physiological functions of the small intestinal mucosa. Regional variations in many of these processes exist along the length of this organ. In the present studies, the glycosphingolipid and ceramide composition of the proximal, middle and distal thirds of the rat small intestine were characterized and compared. Mono‐ and trihexosylceramide were the major neutral glycolipids and hematoside (GM3), the principal ganglioside of this organ. Monohexosylceramide was the major glycolipid of the proximal segment, whereas trihexosylceramide predominated in the distal segments. The total content of neutral glycolipids, ceramide and gangliosides as well as the content of the individual glycosphingolipids and ceramide were highest in the distal segment, intermediate in the middle and lowest in the proximal segment. Additionally, regional variations were noted in the fatty acid composition of the major glycosphingolipids. These differences in the composition of glycolipids and ceramide along the length of the intestine may be responsible, at least partially, for the regional functional specialization seen in this organ.
Retention of linoleic acid in carcass lipids of rats fed different levels of essential fatty acids
Authors: Becker Wulf , Bruce Ake
Published: November 2006

Rats of an inbred Sprague‐Dawley strain were fed purified diets with low (0.3% of total energy), normal (3%) or high (10%) content of essential fatty acids (EFA) for at least three generations. Two 30‐days‐old rats with similar weights were chosen from one litter. One was killed; weight increase and food consumption of the other rat was measured for 15 days. Total lipid content and fatty acid composition in total lipid and lipid classes were determined in both rats. Seven pairs of rats from each group were treated in the same way. Calculations based an amount of linoleic acid ingested and retained in the carcass lipids showed that 50% of the ingested linoleic acid was retained in the low EFA rats compared to 10–15% in the normal and high EFA rats.
Formation of complexes between lecithin and apovitellenin I, an avian egg‐yolk apoprotein
Authors: Fretheim K. , Sleigh R. W. , Burley R. W.
Published: November 2006

In a study of lipid‐protein interactions in egg yolk, it was found that L‐α‐dipalmitoyl lecithin gave two distinct noncovalent complexes (A and B) with apovitellenin I, an apoprotein in the major yolk lipoprotein. Interaction took place under widely varied conditions, and yolk lecithin gave similar complexes. Complex A, which was formed within minutes, consisted of round particles of about 9 nm diameter. Complex B, which was formed more slowly, consisted of larger, particles. Possibly resembling curved discs, with diameter of 30–40 nm. The preparation and some properties of these complexes are described. It is suggested that they may be suitable for an extensive study of phospholipid‐protein interactions in yolk.
Effect of total parenteral nutrition with linoleic acid‐rich emulsions on tissue ω6 and ω3 fatty acids in the rat
Authors: Innis Sheila M.
Published: November 2006

The effect of total parenteral nutrition (TPN) with lipid emulsions containing ca. 48% 18∶2ω6 plus 8% 18∶3ω3 (Intralipid®) or 76% 18∶2ω6 plus 0.5% 18∶3ω3 (Liposyn®) on the fatty acid composition of liver and plasma triglyceride and phospholipid (PL) was studied in the rat. Plasma PL showed a clear influence of the egg PL present in the infused lipid, suggesting replacement of endogenous lipoprotein PL. The incorporation of 20 and 22 carbon ω6 and ω3 fatty acids was reduced in liver phosphatidylcholine of rats infused with either Intralipid or Liposyn. Phosphatidylethanolamine was much less affected and showed reduced 20∶4ω6 and 20∶5ω3 in the Liposyn group only. Reduction in levels of long chain essential fatty acid metabolites was compensated for by an increased content of saturated fatty acids. There was no accumulation of 18∶2ω6 or 18∶3ω3 in liver PL. The similarity between the effects of Intralipid and Liposyn supports the conclusion that 18∶2ω6, not 18∶3ω3, was responsible. The data suggest that intravenous administration of high levels of 18∶2ω6 in parenteral lipid reduces desaturation/elongation of essential fatty acids but does not competitively inhibit esterification of other fatty acids into PL.
Effects of essential fatty acid administration on cardiovascular responses to stress in the rat
Authors: Mills David E. , Ward Ron P.
Published: November 2006

This study examined the effects of 18∶2(n−6), 18∶3(n−6), 20∶4(n−6) and 18∶3(n−3) on cardiovascular responses to isolation stress in male rats. Group‐acclimated rats were fasted for 2 days, then placed on a fat‐free diet. Two wk later animals were divided into six groups (six animals per group) and given eight‐wk intraperitoneal osmotic pumps releasing 1.47×10−7 mol/hr of either olive oil (OL), or of 18∶2(n−6), 18∶3(n−6), 20∶4(n−6) or 18∶3(n−3) in OL. Another group received dummy pumps. Two wk after pump implantation, animals were isolated for four wk. Blood pressure (BP), heart rate and body weight were followed before and during stress. Following the stress period, animals were assessed for cardiovascular reactivity to norepinephrine (NOR) and angiotensin (ANG).

Prior to isolation, 18∶3(n−6) lowered BP vs OL (p<0.01). Stress increased BP within 24 hr in all groups except 18∶3(n−6) and 20∶4(n−6). Treatment with 20∶4(n−6) vs OL prevented the BP rise (p<0.001) only for the first two wk of stress. Administration of 18∶3(n−6) vs OL prevented any BP increase over the four‐wk stress period (p<0.001). Stress increased heart rate in all groups except 20∶4(n−6). Heart rate was lowered by 18∶3(n−6) vs OL (p<0.01) before and during stress. Vascular reactivity to NOR was unaffected by treatment, but OL and 18∶3(n−6) decreased responses to ANG infusion. These data suggest that 18∶3(n−6) supplementation attenuates cardiovascular responses to chronic stress, and that Δ6‐ and Δ5‐desaturase activity are inhibited during chronic psychological stress.
Acetate and mevalonate labeling studies with developingCuphea lutea seeds
Authors: Singh Sheo S. , Nee Thomas Y. , Pollard Michael R.
Published: November 2006

Cuphea seeds contain large amounts of medium chain (C8 to C14) fatty acids, mainly as triacylglycerols. The biosynthesis of these lipids was studied in vivo by incubating developingCuphea lutea seeds with labeled acetate. Incorporation of label into triacylglycerols and into medium chain fatty acids occurred principally during the period of endogenous lipid deposition, but some label was encountered in these products even during seed dehydration. At this later stage palmitate and oleate were the dominant labeled fatty acids. During the period of rapid endogenous lipid deposition acyl lipids other than triacylglycerols were minor labeled components. The labeling patterns were consistent with the Kennedy pathway for triacylglycerol biosynthesis. The fatty acid composition of the acyl‐CoA pool was similar to the total lipid fatty acid composition, but the acyl‐ACP pool contained relatively more short chain acyl groups. Squalene was labeled from acetate throughout the period of seed development, but labeled sterols were not detected. Using [2‐14C]mevalonic acid lactone as substrate, squalene was the principal labeled product. Small amounts of label were found in free sterols. However, in terms of mass, free sterol dominated over squalene. The possibility of two independent sites of isoprenoid biosynthesis in the developing embryo is discussed.
Synthesis of the dipalmitoyl species of diacyl glycerophosphocholine by rabbit alveolar macrophages
Authors: Nakagawa Yasuhito , Waku Keizo
Published: November 2006

The distribution of radioactivity among the molecular species of diacyl glycerophosphocholine of rabbit alveolar macrophages was determined after incubation with [3H]glycerol and 1‐[14C]palmitoyl‐sn‐glycero‐3‐phosphocholine. The highest percentage of radioactivity of [3H]glycerol was found in the dipalmitoyl species (35% of the total) followed by the 1‐palmitoyl‐2‐linoleoyl (23.6%) and 1‐stearoyl‐2‐linoleoyl plus 1‐palmitoyl‐2‐oleoyl species (19.7%) during the first 30 min incubation. The radioactivity of the dipalmitoyl species reached a maximum at 120 min incubation and decreased thereafter, although the radioactivities of other molecular species still increased. In contrast to the [3H]glycerol labeling, only 4% of the total radioactivity in diacyl glycerophosphocholine derived from 1‐[14C]palmitoyl glycerophosphocholine was found in the dipalmitoyl species; 80% of the radioactivity was located in the 1‐palmitoyl‐2‐arachidonoyl species at 10 min incubation. The present results indicate that the dipalmitoyl species of diacyl glycerophosphocholine are synthesized predominantly via a de novo pathway and not the deacylation‐reacylation pathway in rabbit alveolar macrophages.
Subcellular distribution of dietary β‐carotene in chick liver
Authors: Mayne Susan Taylor , Parker Robert S.
Published: November 2006

Studies were conducted examining the subcellular distribution of β‐carotene (BC), α‐tocopherol (E) and retinol (A) in livers of control and BC‐fed male White Leghorn chicks. Chicks were fed Cornell B chick starter diet with or without the addition of 0.5 g BC/kg diet. A first study involved liver fractionation by differential centrifugation in 0.25 M sucrose followed by high performance liquid chromatographic (HPLC) analyses of all fractions for quantitation of BC, E and A. A second study employed both intravenous injection of Triton WR‐1339 four days prior to sacrifice and centrifugation in 1.0 M sucrose to separate mitochondria from lysosomes more efficiently. Fraction purity was assessed by marker enzyme analyses. Results showed that (i) chick liver accumulated BC; (ii) BC‐fed chicks had higher concentrations of BC in all fractions relative to controls, and (iii) the mitochondrial fraction contained the highest concentration of BC, followed by lysosomes, microsomes and nuclei, respectively. Plasma BC increased more than fivefold in BC‐fed chicks. Dietary BC increased A and E levels in liver and in the mitochondrial and lysosomal fractions while the plasma E level was decreased. Plasma A changed little with BC feeding. While dietary BC had no effect on fatty acid composition of subcellular fractions, the increase in E resulted in a large increase in the molar ratio of E to polyunsaturated fatty acids. The incorporation of BC and increased amounts of E into cellular mebranes presumably would result in increased resistance to peroxidative damage.
A method for isolation of milk fat globules
Authors: Patton Stuarf , Huston Gail E.
Published: November 2006

The traditional procedure for isolating milk fat globules involves repeated cycles of centrifuging to obtain globules and redispersion of them in fresh buffer to eliminate other milk components. We have evaluated a simpler, less manipulative method whereby globules are centrifuged out of the milk and through an overlying buffer layer. Human milk samples ranging from 0.1 to 35 ml were centrifuged at 1500×g for 20 min after deposition under a suitable quantity of buffer. This yielded purified globules, in less time, which could be dispersed more satisfactorily than those by the traditional procedure. Protein, phospholipid and cholesterol contents of globules by the two methods were quite similar. A lower protein content (10.4 vs 13.2 mg/g of lipid) was characteristic of globules prepared by the multiple wash method. However, large differences could not be seen in gel electrophoresis patterns of the proteins. By using plastic centrifuge tubes, tube freezing and cleavage just below the globule layer enables clean separation of globule and nonglobule phases for analysis of milk component distributions. Macro (5 to 35 ml of sample) and micro (200 μl or less) versions of the method are described. Limited trials showed that the method can be applied satisfactorily to cow's and goat's milks, but for highly pure globules a deeper buffer column than that used with human milk is required because of their much higher casein content.
Two geometrical isomers of linoleic acid: Improved total syntheses
Authors: Ofsuki Tetsuo , Brooker Robert F. , Funk Max O.
Published: November 2006

The total syntheses of 9(Z),12(E)‐ and 9(E),12(Z)‐octadecadienoic acids have been carried out. A useful intermediate in both syntheses, 8‐bromo‐octanoic acid, recently has become available from commercial sources. This compound has been used to expedite the preparation of these isomers. The remaining carbon atoms were derived from propargyl alcohol along with either 1‐heptyne or acetylene and 1‐bromopentane. Because the overall yield for each sequence was roughly 15% and there were no extraordinary reaction conditions in any of the synthetic steps, the compounds could be prepared readily in multiple gram quantities. The syntheses of the two compounds were supported by data from a variety of spectroscopic techniques.
Mammary transfer and metabolism in the rat of halogenated fatty acids of halogenated olive oil
Authors: Conacher H. B. S. , Chadha R. K. , Lawrence J. F. , Charbonneau S. M. , Bryce F.
Published: November 2006

To assess possible incorporation of halogenated fatty acids into the neonate via the milk, a 4‐day study was carried out in which lactating Wistar rats were orally dosed with either brominated olive oil (BOO) (0.6 g/kg body wt/day) or chlorinated olive oil (COO) (0.4 g/kg body wt/day) for the first 4 days. On days 1–5 inclusive 2 pups per litter were sacrificed and the stomach curd and livers analyzed for halogenated fatty acids by gas liquid chromatography (GLC). On day 5 all dams also were sacrificed and their livers and adipose tissue similarly analyzed. With BOO, brominated fatty acids (bfa) accumulated in both the milk lipids and neonate liver lipids, and appeared to plateau on day 4 at levels of 2% and 5% respectively. In contrast to the BOO in which approximately 100% of the bfa was dibromostearis (DBS), the milk bfa comprised 79% (DBS), 9% dibromopalmitic (DBP) and 12% dibromomyristic (DBM) acids, suggesting maternal metabolism to the shorter chain brominated acids. In the neonate liver lipids the bfa composition was 47% (DBS), 12% (DBP) and 41% (DBM), suggesting either further metabolism in the neonate and/or preferential accumulation of the shorter chain brominated acids. The analysis of maternal tissue indicated very low bfa residues, contrary to previous studies in non‐lactating rats. Similar results were obtained with COO.
Fatty acid and squalene compositions of mediterraneanCentrophorus SPP egg and liver oils in relation to age
Authors: Peyronel D. , Artaud J. , Iatrides M. C. , Rancurel P. , Chevalier J. L.
Published: November 2006

The liver oil content of seven MediterraneanCentrophorus spp. were studied together with the oil of one unfertilized egg and one yolk bag. The relative weight of the liver ranges from 15 to 29% of total body weight; 63 to 89% of the liver weight is oil. Squalene, the major component (49–89% in oil) of the unsaponifiable fraction, is directly quantified by GLC following TLC separation. The squalene level increases with the age of the animals. More than 50 fatty acid species were identified. Among them, the most abundant are: 16∶0 (22–27%), 18∶1ω9 (21–36%) and 22∶6ω3 (2–18%). The level of ω3‐fatty acids, essential in the fishes, shows a maximum in the egg (26%), decreases to a minimum in the young (5%) and stabilizes to an intermediate level in the adult (12%).
The distribution of serum high density lipoprotein subfractions in non‐human primates
Authors: Nelson Charles A. , Greer William E. , Morris Manford D.
Published: November 2006

The ultracentrifugal flotation patterns in 1.2 g/ml solvent and ultracentrifugal gradient distribution of high density lipoproteins (HDL) from the primates‐human, apes and monkeys‐were determined, with emphasis on the gorilla species of apes and rhesus monkeys. Diets for non‐human primates were commercial chow, which is low in cholesterol. Molecular weights and protein, cholesterol, phospholipid and triglyceride compositions of various density fractions were determined on human, gorilla and rhesus HDL. The HDL2/HDL3 ratio was determined from the two peaks observed upon flotation in high salt in the analytical ultracentrifuge. The HDL2 of all three species of apes‐gorillas (Gorilla gorilla), chimpanzees (Pan troglodytes) and orangutans (Pongo pygmaeus)—was always greater than HDL3, while that of all six species of Old World monkeys‐Rhesus (Macaca mulatta), sooty mangabeys (Cercocebus atys), cynomolgus (Macaca fascicularis), stumptails, (Macaca arctoides) patas (Erythrocebus patas) and African greens (Cercopithecus aethiops)—was less. In addition, the HDL3 concentration in five gorillas was about 15 mg/dl as cholesterol while the HDL2 concentration was 92 mg/dl, much lower and higher, respectively, than humans. HDL2 of gorillas was similar in density and molecular weight to that of humans. The distribution of densities in gorilla HDL was predominantly in HDL2, while rhesus HDL usually, but not always, was unimodal, having a density distribution similar in heterogeneity to human HDL3, but somewhat less dense (peaking at 1.109 vs 1.129 g/ml). The molecular weight of rhesus HDL was about the same as human HDL3 in all three density subfractions and at the peak density. Likewise, the chemical compositions were similar for the subfractions 1.10–1.125 and>1.125 g/ml for rhesus HDL and human HDL3. Consequently most but not all chow‐fed rhesus HDL was very similar to human HDL3, but lighter in density.
Milk fat structure of a patient with type 1 hyperlipidemia
Authors: Myher J. J. , Kuksis A. , Steiner G.
Published: November 2006

Structural analyses were performed on milk fat samples obtained 3–10 days postpartum from a lactating patient with primary Type 1 hyperlipidemia. The milk triacylglycerols contained 3–7% C10, 14–21% C12, 20–30% C14, 22–26% C16 and 20–30% C18 (largely oleic) acids. Gas liquid chromatographic (GLC) analyses of the X‐1,3‐ and X‐1,2‐diacylglycerols on polar siloxane columns showed a markedly non‐random association of acyl chains. Stereospecific analyses indicated that the short chain length fatty acids were confined essentially to the sn‐3‐position of the triacylglycerol molecule. Furthermore, these acids were largely absent from the phosphatidylcholines and the endogenous sn‐1,2‐diacylglycerols of the milk fat. It is concluded that the short chain fatty acids are incorporated into the milk triacylglycerols during the final stage of biosynthesis via the phosphatidic acid pathway, and that the overall fatty acid distribution is consistent with the 1‐random 2‐random 3‐random hypothesis.
Studies of triacyglycerol structure of very low density lipoproteins of normolipemic subjects and patients with type III and type IV hyperlipoproteinemia
Authors: Myher J. J. , Kuksis A. , Breckenridge W. C. , Little J. A.
Published: November 2006

The triacylglycerols of very low density lipoproteins (VLDL‐TG) were analyzed in samples from normal subjects and patients with Frederickson’s Type III and Type IV hyperlipoproteinemia. VLDL were obtained by conventional ultracentrifugation, and the triacylglycerols were isolated by thin‐layer chromatography (TLC). Representative sn‐1,2(2,3)‐ and sn‐1,3‐diacylglycerols were generated by Grignard degradation of the triacylglycerols, and were resolved by TLC on borate‐treated silica gel. The molecular association of the fatty acids in the diacylglycerol moieties was determined by gasliquid chromatography with mass spectrometry (GC/MS) of the tertiary‐butyldimethylsilyl ethers. The positional distribution of the fatty acids was established by the Brockerhoff stereospecific analysis. The results showed a marked asymmetry in the distribution of the fatty acids in all samples, with the saturated acids predominantly in the sn‐1‐position and the unsaturated fatty acids distributed about equally between the sn‐2‐ and sn‐3‐positions. In all instances, the molecular species composition of the sn‐1,2‐, sn‐2,3‐ and sn‐1,3‐diacylglycerols was found to be similar to that calculated for 1‐random 2‐random 3‐random distribution of triacylglycerols. There were marked differences in the quantitative composition of the molecular species of the VLDL‐TG between normal subjects and patients, but these discrepancies were attributed to differences in the fatty acid composition of the samples.
Purification of lysosomal cholesteryl ester hydrolase from rat liver by preparative isoelectric focusing
Authors: Klemets Rabbe , Lundberg Bo
Published: November 2006

Ion‐exchange chromatography and preparative isoelectric focusing (PIEF) were compared to produce a stable rat liver lysosomal cholesteryl ester hydrolase of high specific activity. The PIEF purification method proved to be more rapid and easier to perform. PIEF purification involved the following steps: i) osmotic shock of the lysosome fraction, ii) (NH4)2 SO4 precipitation (10–70%, w/v), iii) Sepharose CL‐6B gel filtration, and iv) PIEF. The enzyme was purified 60–120‐fold with a yield of 2–4%. The activity of the purified enzyme was best restored by stabilizing with a 0.5% (w/v) albumin solution. The purified enzyme produced one major band on SDS‐polyacrylamide gel electrophoresis having a MW of 58,500 daltons. Gel filtration showed a MW of 58,000 daltons. The optimum pH of the enzyme was 4.5, and the isoelectric point was 6.0–6.2. The specific activity of hydrolysis of cholesteryl oleate and triolein increased by similar rates during purification.
Dihomo‐γ‐linolenic acid reverses hypertension induced in rats by diets rich in saturated fat
Authors: Hassall Cedric H. , Kirtland Stephen J.
Published: November 2006

This study has shown that hypertension induced in rats by a diet rich in saturated fat (16% coconut oil, 4% palmitic acid by weight) is reversed by the addition of the essential fatty acid, dihomo‐γ‐linolenic acid (DHLA), at 5.0% but not at 0.5% of dietary energy. This potent effect of DHLA has been attributed to modulation of prostaglandin biosynthesis.
Brominated fatty acid distribution in tissues and fluids of rats fed brominated vegetable oils
Authors: Lawrence James F. , Chadha Rajinder K. , Iverson Frank , McGuire Peter , Conacher Henry B. S.
Published: November 2006

Rats dosed orally for four days with 0.24 g/kg body weight per day of brominated olive oil (BOO) or brominated sesame oil (BSO) were found to accumulate dibromostearic (DBS) acid (from BOO) and DBS and tetrabromosteric (TBS) acids (from BSO) in the liver, heart and adipose tissue. The metabolites, dibromopalmitic, and dibromomyristic acids (from BOO and BSO), as well as their tetrabromo‐analogues (from BSO) were found as determined by gas chromatography with halogen specific detection and confirmed by gas chromatography‐mass spectrometry. Blood contained no DBS, TBS or metabolites. However, inorganic bromide was observed in both blood and urine while none was observed in the feces. The latter contained significant quantities of both DBS and TBS but showed the absence of the four brominated metabolites.
Incorporation of arachidonic acid and eicosapentaenoic acid into phospholipids by polymorphonuclear leukocytes in vitro
Authors: Tou Jen‐Sie
Published: November 2006

The present study demonstrated that the patterns of the incorporation of [1‐14C] arachidonic acid and [1‐14C] eicosapentaenoic acid into individual phospholipids by polymorphonuclear leukocytes were similar. However, human leukocytes exhibited higher activity than guinea pig periotoneal leukocytes in the formation of arachidonoyl‐ and eicosapentaenoyl‐phosphatidic acid. Cells from both origins showed a decrease of label in phosphatidylcholine accompanied by an increase of label in phosphatidylethanolamine after a longer period (30–120 min) of incubation, suggesting that part of the arachidonoyl or eicosapentaenoyl moiety in phosphatidylethanolamine may be derived from that of phosphatidylcholine. The observed difference between human cells and elicited cells in the time‐course of the incorporation of both fatty acids into phosphatidylcholine and phosphatidylethanolamine appears to be due to different contents of the diacyl and ether‐linked class compositions of these phospholipids in cells from different origins. Both labeled fatty acids were incorporated more rapidly into the diacyl‐linked class, but were retained to a greater extent in alkylacyl‐phosphatidyl‐choline and alkenylacyl‐phosphatidylethanolamine. The data suggest that, in addition to alkylacyl‐phosphatidylcholine and phosphatidylinositol, alkenylacyl‐phosphatidylethanolamine may be an important endogenous source of arachidonic acid and eicosapentaenoic acid in stimulated human leukocytes.
Studies on peroxidized lipids. V. Formation and characterization of 1,4‐dihydropyridine‐3,5‐dicarbaldehydes as model of fluorescent components in lipofuscin
Authors: Kikugawa K. , Ido Y.
Published: November 2006

We investigated fluorescence properties of 1,4‐dihydropyridine‐3,5‐dicarbaldehydes and their formation in mild reaction of primary amines and malonaldehyde, in order to clarify the role of malonaldehyde in the formation of fluorescent components of lipofuscin. The compounds exhibited fluorescence with excitation maxima at 375–405 nm and emission maxima at 435–465 nm, which was similar to those of lipofuscin and the fluorescent substances derived from the reaction of oxidized fatty acids with primary amines. Fluorescence of the compounds was greatly affected in acidic medium and little influenced in alkaline medium or by the metal chelator. The compounds lost fluorescence by treatment with sodium borohydride. They were inert to thiobarbituric acid reaction. Some of the fluorescence properties of the compounds were different from those of lipofuscin and the related fluorescent substances. Mild reaction of methylamine with pure malonaldehyde gave a single fluorescent compound, 1,4‐dimethyl‐1,4‐dihydropyridine‐3,5‐dicarbaldehyde (Ia), and the reaction with the acid hydrolysate of tetramethoxypropane gave Ia and 1‐methyl‐4‐(dimethoxyethyl)‐1,4‐dihydropyridine‐3,5‐dicarbaldehyde (IIa), the latter being produced from the impurity in the hydrolysate. These reactions produced a non‐fluorescent Schiff base, a 1∶1‐adduct of methylamine and malonaldehyde (IIIa), as a major product. It looks unlikely that malonaldehyde is the only product of lipid oxidation that produces fluorescent components in lipofuscin complex.
Alteration and recovery of bleeding times, platelet aggregation and fatty acid composition of individual phospholipids in platelets of human subjects receiving a supplement of cod‐liver oil
Authors: Ahmed Ahmed A. , Holub Bruce J.
Published: November 2006

The effect of supplementation with cod‐liver oil containing eicosapentaenoic acid (EPA), 20∶5ω3, on bleeding times, thrombin‐induced platelet aggregation, platelet protein, platelet cholesterol, and the level and fatty acid composition of individual phospholipids in the platelets of human subjects was determined. Measurement of these parameters was conducted before the subjects received the supplement (day 0), after they received the supplement for 14 days (day 14), and 14 days after the supplement was terminated (day 28) so as to monitor recovery. The mean bleeding times exhibited a marked increase (by 81%) with supplementation and returned to near basal (day 0) values within 14 days after the supplement was terminated. Cod‐liver oil supplementation significantly reduced thrombin‐induced platelet aggregation with a partial recovery being exhibited by day 28. The content of phospholipid, cholesterol and protein (μg/109 platelets) was not significantly different (P>0.05) when isolated from the subjects at day 0, 14 and 28, as neither were the composition of individual phospholipids [phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI) and sphingomyelin (SPH)] given as % of total phospholipid. However, the fatty acid compositions of all platelet phospholipids were altered significantly by the fish oil supplement. In PC, EPA rose from 0.3 to 2.9% of total fatty acids and docosahexaenoate from 0.7 to 1.8% concomitant with a drop in arachidonate (from 14.1 to 9.6%) and linoleate (from 10.2 to 7.9%); these levels approached basal levels 14 days after supplementation was terminated. The highest percentage of EPA with supplementation was found in PE (4.3%), while the arachidonate fell from 38.8 to 30.5%, with low percentages of EPA occurring in PS (0.7%) and PI (0.5%). The level of 24∶1 in SPH increased significantly (from 17.8 to 24.8) with supplementation and reverted to basal values by day 28. These results suggest a close relationship of the observed fatty acid changes in individual platelet phospholipids to the altered hematological parameters and platelet‐vessel wall interactions produced by cod‐liver oil supplementation.
Analysis of molluscan sterols: Colorimetric methods
Authors: Swift Mary L.
Published: November 2006

The wide variety of sterols normally found in extracts of bivalve molluscs leads to high variability in analytical data obtained with colorimetric (chole)sterol methods. Total sterol levels in oyster (Crassostrea virginica) extracts were determined using the Liebermann‐Burchard reagent, an acid‐FeCl3 reagent and a cholesterol oxidase procedure. The data from the latter two agreed to within 5.4% and yielded about 30% higher estimates of sterol content than the Liebermann‐Burchard test. Gas‐liquid chromatographic data also are compared.

Several pure sterols, selected because of their presence in oyster sterol fractions or because of their structural similarities to such sterols, were examined using each of the three procedures. Sterols, differing from cholesterol only with regard to the side chain, reacted 80–102% as well as cholesterol with the acid‐FeCl3 reagent and cholesterol oxidase. The Liebermann‐Burchard reaction was more specific for cholesterol. The colorimetric cholesterol oxidase method is recommended for the estimation of total molluscan sterol content.
Squalene isolation by HPLC and quantitative comparison by HPLC and GLC
Authors: Sulpice J. C. , Férézou J.
Published: November 2006

A new procedure is described for isolating and measuring squalene in plasma and in several organs of the rat. The unsaponifiable material was fractionated by normal phase HPLC on a silica gel column using a mobile phase consisting of hexane/propanol‐2/water. The eluate was monitored at 215 nm. The squalene in the hydrocarbon fraction thus collected was than quantified on an analytical column eluted with hexane. Squalene concentrations ranging from 3 to 200 μg per ml of plasma or per g of fresh tissue were accurately measured. The results obtained agree with those of the squalene assays carried out by gas chromatography on a packed or capillary column.
Cholesteryl ester hydrolysis in rat liver cytosol. Modulation by female sex hormones
Authors: Gandarias J. M. , Lacort M. , Ochoa B.
Published: November 2006

The regulation of cholesterol ester hydrolase activity by female sex hormones was studied in cytosolic preparations from female rat liver. The investigation was undertaken in order to determine whether a reduction in the enzyme activity might be responsible for the increased content of esterified cholesterol found in rat liver after estradiol or progesterone treatments. The single injection of estradiol (0.75 mg/100 g) or progesterone (1.50mg/100g) produced respectively significant decreases and increases in sterol hydrolase activity. Both opposite effects were noted after a similar lag period of 3–4 hr and were of short duration. No alterations were observed in rats receiving short‐term treatments. When hormones were added to the incubation medium, the activity of cholesterol ester hydrolase decreased progressively with increasing concentrations of hormones. Kinetic studies demonstrate that both estradiol and progesterone compete with the substrate (cholesteryl oleate) for the active center. The findings of the present paper exclude a direct relationship between hepatic hydrolytic activity and lipid deposition. However, they provide evidences that female sex hormones act as modulatory agents of the hydrolysis of cholesteryl esters in rat liver cytosol and suggest that other factors besides competitive inhibition are involved in such regulatory effects.
Characterization of γ‐linolenic acid inRibes seed
Authors: Traitler Helmut , Winter Heike , Richli Urs , Ingenbleek Yves
Published: November 2006

The total lipid content of fruit seeds of theRibes family ranges by weight from 18.3% in gooseberries (Ribes uva Crispa) to 30.5% in black currants (Ribes nigrum). Isolation procedures and analytical methods (gas chromatography, mass spectrometry, high performance thin layer chromatography and stereospecific analysis) demonstrate that the oils fromRibes seeds contain up to 19% by weight of γ‐linolenic acid (γ‐LA, C18∶3, n−6) in black currant oil. This lastRibes species thus constitutes one of the richest natural sources in γ‐LA yet described. These oils appear promising for critically ill patients who seem unable to convert linoleic acid into subsequent EFA fractions.
Cholesterol blocks the disordering effects of ethanol in biomembranes
Authors: Chin Jane H. , Goldstein Dora B.
Published: November 2006

To assess the relation between the physical order of a membrane and its sensitivity to ethanol, we enriched biomembranes with cholesterol, both in vivo and in vitro. Japanese quail of the SEA line (selectively bred for susceptibility to experimental atherosclerosis) were treated for 9 to 16 weeks with a diet that contained 2% cholesterol. This regimen increased the cholesterol content of serum and erythrocytes. The cholesterol content of brain synaptosomal plasma membranes (SPM) was unaffected by the high cholesterol diet. In other experiments, isolated mouse synaptosomal plasma membranes were incubated with cholesterol/phospholipid (C/P) vesicles; different amounts of cholesterol were transferred according to the sterol content of the donor vesicles. Membrane order was determined in both types of membranes by a sensitive electron paramagnetic resonance (EPR) technique. The order parameter with 5‐ and 12‐doxylstearic acid increased along with the cholesterol content. As expected, ethanol disordered membranes (decreased the order parameter) in a concentration‐related manner. The slope of the concentration response curve was less steep in high cholesterol than low cholesterol membranes, indicating that cholesterol enrichment partially blocks the membrane action of ethanol in both types of membranes.
Homeostatic control of membrane fatty acid composition in the rat after dietary lipid treatment
Authors: Gibson R. A. , McMurchie E. J. , Charnock J. S. , Kneebone G. M.
Published: November 2006

Diets in which both the lipid content and composition (polyunsaturated to saturated fatty acid ratio) were varied were fed to rats for 20 weeks, and the effects on the tissue lipid profiles were determined. The fatty acid profile of the plasma lipids, and the phospholipid fatty acids of the mitochondrial and microsomal fractions of liver, heart, kidney and brain, as well as erythrocyte membranes were determined. Despite large differences in the level and type of lipid present in the experimental diets and in the proportion of saturated fatty acids in the plasma lipids in response to the various diets, there was little effect on the proportion of saturated to unsaturated fatty acids in the phospholipids of the various membranes examined. The major effect of altering the dietary level of polyunsaturated to saturated fatty acids was on the ratio of the ω6/ω3 series of unsaturated fatty acids in the membrane lipids. This change occurred in all tissues except the brain, in which only a small response to altered dietary lipid intake was observed. The ω6/ω3 ratio was elevated upon feeding a diet rich in ω6 polyunsaturated fatty acids, but decreased when a diet rich in saturated fatty acids was fed. The failure to significantly alter membrane lipid saturation/unsaturation in the tissues examined would suggest that a homeostatic mechanism is operative in biological membranes and may act to buffer membranes from the effects of changes in the nature of the dietary lipid intake.
Lipid composition of millet (Pennisetum americanum) seeds
Authors: Osagie A. U. , Kates M.
Published: November 2006

The composition of lipids extracted from a sample of millet seeds by each of 8 solvent systems is reported. Lipid components were separated by silicic acid column and thin layer chromatography (TLC) and quantitated by analysis of fatty acid methyl esters by gas liquid chromatography (GLC), with heptadecanoic acid as internal standard. Best results were obtained by extraction with hot water‐saturated butanol. Lipids extracted amounted to 7.2% of the seed dry weight and consisted of 85% neutral lipids, 12% phospholipids and 3% glycolipids. Neutral lipids contained mostly (85%) triacylglycerols and small amounts of mono‐ and diacylglycerols, sterols and free fatty acids. Sterols consisted of campesterol, stigmasterol and 2 unidentified sterols, occurring in the same proportions in free and esterified forms. Ten glycolipid and 10 phospholipid components were separated and characterized. Contrary to previously published observations, lysophosphatidylcholine was the major phospholipid (42%) in millet seeds; smaller amounts of phosphatidylcholine (24%), lysophosphatidylethanolamine (21%) and trace amounts of phosphatidylglycerol, phosphatidic acid, phosphatidylserine and phosphatidylinositol also were present. The major glycolipids were esterified sterol glycoside, sterol glycoside, monogalactosyldiacylglycerol, digalactosyldiacylglycerol and cerebrosides (ceramide monohexosides).
A modified radiometric assay for 3‐hydroxy‐3‐methylglutaryl coenzyme a reductase
Authors: Georgopapadakou Nafsika H. , Dix Barbara A.
Published: November 2006

A radiometric assay for measuring the activity of 3‐hydroxy‐3‐methylglutaryl‐coenzyme A (HMG‐CoA) reductase is described. The assay is based on the separation of the mevalonate product from HMG‐CoA by high‐voltage electrophoresis. This method is more sensitive and more specific than the NADPH‐based spectrophotometric assay, and less tedious than available radiometric assays. It has been used to measure HMG‐CoA reductase activity in crude extracts ofSaccharomyces cerevisiae and in human skin fibroblasts.
Effects of organic solvents on lipase for fat splitting
Authors: Kim Kee H. , Kwon Dae Y. , Rhee Joon S.
Published: November 2006

The effect of organic solvents on the stability and catalytic activity of the microbial lipase fromCandida rugosa for hydrolysis of triglyceride (fat splitting) has been examined. The solvents examined were 5 hydrocarbons (n‐hexane, n‐heptane, n‐octane, iso‐octane and cyclohexane) and 3 ethers (diethyl‐ether, diisopropylether and di‐n‐butylether). The results revealed that iso‐octane and cyclohexane are superior to the other solvents examined for enzymatic fat splitting in organic solvent systems.