bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparisons of monoacylglycerols and diacylglycerols of varying fatty acid composition as substrates for the acylglycerol kinase(s) of rat brain
Authors: Bishop H. H. , Strickland K. P.
Published: November 2006

Asstract

The properties of diacylglycerol and monoacylglycerol kinase activities present in 90,000 x g pellet and 90,000 × g supernatant fractions from rat brain were examined and compared. Of the properties examined, time course (linear for 10 min), enzyme concentration, pH optimum (7.4–7.5), varying ATP (5 mM) and Mg2+ (10 mM) concentrations all showed similar optima for both activities. The optima for acylglycerol (5 mM for diacylglycerols; 3 mM for monoacylglycerols) and deoxycholate concentrations (0.1% for diacylglycerol kinase; 0.03% for monoacylglycerol kinase) differed slightly. Examination of the subcellular distribution for these activities also showed a similar pattern. All fractions showed significant activities, but the most was in the supernatant fraction. The similarities in properties and localization of the 2 kinase activities suggest a single enzyme may function. On this assumption, an extensive study using mono‐ and diacylglycerols of varying fatty acid composition gave the following results: (a) acylglycerols with the same fatty acid present showed increasing activity in the order: 1‐monoacylglycerol, 2‐monoacylglycerol and 1,2‐diacylglycerols; (b) when saturated fatty acids were present the order of decreasing activity varied directly with increasing chain length for C10→C20; (c) when one or more unsaturated fatty acids were present good activities resulted, but no clear pattern emerged, although acylglycerols with18∶1 and18∶3 fatty acids were more active than those with18∶2 and20∶4 fatty acids. These patterns do not support a role for this kinase in producing phosphatidic acids or lyso phosphatidic acids of the correct composition to act as precursors for the de novo synthesis of the predominant 1‐stearoyl, 2‐arachidonoyl molecular species of phosphatidylinositol.
Dietary arachidonic acid reduces fatty liver, increases diet consumption and weight gain in ethanol‐fed rats
Authors: Goheen Steven C. , Larkin Edward C. , Manix Marcia , Rao G. Ananda
Published: November 2006

We fed young male Sprague‐Dawley rats for 4 wk ad libitum liquid diets containing 34% of the calories as ethanol and 35% as fat with (AA+) and without (AA−) arachidonic acid (20∶4). Additional rats in the control groups were fed similar diets made isocaloric with dextrose with (CA+) and without (CA−) 20∶4. The liver triglyceride (TG) content of rats in the AA+ group was reduced ca. 3‐fold over that of rats in the AA‐group. The diet consumption and body wts of rats in the AA+ group were significantly greater than those of rats fed alcohol without the 20∶4 supplement (AA−). Also livers from rats in the AA+ group were as large as those from rats in control groups (CA+, CA−) and ca. twice as large as those from rats in the AA‐group. The fatty acid composition of liver TG in rats fed the alcohol diet was similar to that of dietary fat. Levels of 20∶4 and docosatetraenoic acid (22∶4) in liver TG fatty acids from rats fed diets without arachidonate (AA−, CA−) were low (trace to 1.6%). After ingestion of arachidonic acid, 20∶4 increased to ca. 10% and 22∶4 to ca. 5%. The content of liver phospholipids was higher in livers of rats fed ethanol (AA−) than in those of controls (CA−).
Distribution of high density and other lipoproteins in selected LRC prevalence study populations: A brief survey
Authors: Rifkind Basil M. , Tamir Israel , Heiss Gerardo , Wallace Robert B. , Tyroler Herman A.
Published: November 2006

Selected lipid and lipoprotein data from the Lipid Research Clinics (LRC) Prevalence Study are presented, with particular emphasis given to high‐density lipoprotein (HDL) values. Cross‐sectional age‐and sex‐specific mean values are shown for 7007 white participants in the ten North American LRCs. Comparisons are drawn for males and females (including the pediatric group) and for females using or not using sex hormones. The US‐USSR Collaborative Program is summarized, and selected comparisons are noted for the Soviet and United States samples.
Fatty acids of cerebrosides in different regions of the developing foetal brain
Authors: Rao P. Srinivasa
Published: November 2006

The fatty acid composition of cerebrosides of developing foetal human brain and regional variations, if any, during intrauterine life were studied. While palmitic and stearic acids were the predominant normal fatty acids throughout intrauterine life, long chain fatty acids, like lignoceric and nervonic acids, which were low at early gestational ages, rapidly accumulated at term. Regional differences were observed in the concentrations of long chain normal fatty acids especially at term. Medulla oblongata showed a greater accumulation of long chain fatty acids as compared to the cerebellum and cerebrum. The distribution of 2‐hydroxy fatty acids in different regions showed a pattern predominantly that of long chain carbon units, even at 34 wk of foetal life. A higher ratio of lignoeric to stearic acid in the case of normal fatty acids, probably indicative of chain elongation, was also evident in the case of medulla oblongata and cerebellum as compared to the cerebrum. The significance of these qualitative alterations in relation to rapid growth of brain prior to term and the process of myelination has been discussed.
Comparative effects of (−)‐hydroxycitrate and (+)‐allo‐hydroxycitrate on acetyl CoA carboxylase and fatty acid and cholesterol synthesis in vivo
Authors: Triscari Joseph , Sullivan Ann C.
Published: November 2006

(−)‐Hydroxycitrate and (+)‐allo‐hydroxycitrate were investigated for their effects on lipid synthesis in vivo under conditions of either high carbohydrate feeding or 24 hr fasting. Changes in rates of lipid synthesis resulting from the oral administration of these compounds were monitored with the use of radiolabeled H2O, alanine, and acetate. In the fed rat, (−)‐hydroxycitrate significantly reduced the incorporation of H2O and alanine into fatty acids and cholesterol. An increased incorporation of labeled H2O into fatty acids but no change in cholesterol synthesis in the fasted rat suggested that (−)‐hydroxycitrate may be an activator of acetyl CoA carboxylase. With (−)‐hydroxycitrate administration, acetate incorporation into fatty acids and cholesterol was subject to pool dilution effects under fed or fasted states. (+)‐allo‐Hydroxycitrate was ineffective in modulating the rates of fatty acid synthesis under either nutritional condition. Both (−)‐hydroxycitrate and (+)‐allo‐hydroxycitrate were shown to be in vitro activators of acetyl CoA carboxylase, the former being a much stronger activator than the latter. Thus, stereospecificity of the hydroxycitrate isomers was demonstrated in both the inhibition of lipid synthesis (previously shown to occur at adenosine triphosphate citrate lyase) and the stimulation of fatty acid synthesis (possibly occurring at acetyl CoA carboxylase).
Erucic acid and phospholipids of newborn rat heart cells in culture
Authors: Rogers C. G.
Published: November 2006

Erucic acid (Δ13‐docosenoic acid), labeled with14C in the 1‐or 14‐position, was incorporated into fetal calf serum and fed to beating, neonatal rat myocardial cells in culture. Uptake of the docosenoic acid during the first 6 hr of incubation was 41 nM/hr/mg protein in 7‐day old cells and 29 nM/hr/mg protein in 14‐day old cells. Fifty‐seven percent of the14C‐activity was taken up from the medium in 24 hr, of which 77% was in the cells and 23% was unaccounted for. Of the14C‐activity taken up, 26% was in extractable lipid, with two‐thirds in neutral lipid and one‐third in phospholipid. Within the neutral lipid fraction, 88% of the14C‐activity was present in triglycerides; while in phospholipids, 66% of the14C‐activity was in phosphatidylcholine (PC); 14% in phosphatidylethanolamine (PE); 6% in sphingomyelin (SPH) and 1% or less in cardiolipin (DPG). PC had the highest specific activity, followed by SPH and PE. The specific activity of PE was one‐half that of SPH when the14C‐erucic acid substrate was labeled at the carboxyl position, but increased to equal that of SPH when the substrate was labeled at the double bond. The fatty acids of PC, PE, and SPH were influenced by erucic acid in the growth medium, but the amounts of each phospholipid were not affected. It is proposed that the altered fatty acid composition associated with incorporation of erucic acid or its metabolites into PC, PE, and SPH may affect integrity and function of heart cell membranes.
Effects of dietary antioxidants on in vivo lipid peroxidation in the rat as measured by pentane production
Authors: Downey Jeanne E. , Irving Dennis H. , Tappel Al L.
Published: November 2006

The hypothesis that pentane is an in vivo product of lipid peroxidation was confirmed by a study of the effects of a nonbiological antioxidant on pentane production in rats fed a diet deficient in vitamin E and supplemented with 0.01% N,N′‐diphenyl‐p‐phenylenediamine (DPPD). Seven rats were fed a vitamin E‐deficient diet starting at 3 wk of age. After 5 wk, 0.01% DPPD was added to the diets of three rats (group DPPD) while the diet of the other four rats remained unchanged (group OE). Within 2 wk of the diet change, rats in group DPPD exhaled 65% less pentane than rats of the same age in group OE. After 5 wk of being fed the DPPD‐supplemented diet, rats in group DPPD were again fed the basal vitamin E‐deficient diet; within 3 wk, these rats produced pentane levels similar to those of rats in group OE. The effects of vitamin E depletion and repletion on in vivo lipid peroxidation in rats were also studied. Three groups of three rats each were initially fed a vitamin E‐deficient diet starting at 3 wk of age. After 8, 8, and 5 wk of being fed this diet, the three groups were fed diets supplemented with 3.3 (group 0→3.3E), 11 (group 0→11 E), and 200 (group 200E) i.u. vitamin E acetate/kg diet, respectively. Another group of three rats (group 11 E) was fed a diet supplemented with 11 i.u. vitamin E/kg starting at 3 wk of age for the duration of the study. There were significant decreases in pentane production by rat groups 0→3.3E, 0→11E, and 200E within 2 wk of the change to the vitamin E‐supplemented diets. After about 5 wk of being fed their respective vitamin E‐supplemented diets, pentane breath levels had stabilized. Breath pentane levels were inversely proportional to the log of dietary vitamin E concentration.
Cerebral prostaglandin synthesis during the dietary and pathological stresses of essential fatty acid deficiency and experimental allergic encephalomyelitis
Authors: Weston Patricia G. , Johnston Patricia V.
Published: November 2006

Rats of the Lewis strain were fed diets adequate or deficient in essential fatty acids (EFA). At 70–80 days of age experimental allergic encephalomyelitis (EAE) was induced using adjuvants containing eitherMycobacterium butyricum orMycobacterium tuberculosis H37Ra. When the formerMycobacterium was used, the incidence of EAE was greater in the EFA‐deficient than in EFA‐adequate controls; but when the rats challenged withM. tuberculosis, the incidence of the disease was the same in both dietary groups. Brain slices from EFA‐deficient rats had a marginally depressed synthesis of prostaglandin F (PGF) compared to that of controls. Immunochallenge with adjuvant alone or adjuvant plus antigen tended to depress further PGF synthesis by brain slices from EFA‐deficient rats and significantly depressed synthesis by slices from rats receiving adequate EFA. Whether or not rats were paralyzed had no effect on PGF synthesis when the diet was adequate in EFA, but a significant difference was seen in the EFA‐deficient group. The results indicate a possible role for PGF synthesis in the degree of susceptibility of the rats to EAE under different dietary regimens.
Effect of pentadecan‐2‐one on lipid metabolism in HeLa cells
Authors: Naccarato W. F. , Gilbertson J. R.
Published: November 2006

HeLa cells exposed to trace amounts of pentadecan‐2‐one showed changes in metabolism of 1‐14C‐palmitate. These changes consisted of an increased incorporation of radioactivity into the triglycerides and free fatty acids and a decreased14C incorporation into the ether moiety of alk‐1‐enyl acyl phosphoglycerides. Chemical analysis of the several lipid fractions showed a threefold increase in triglyceride content but no change in the amount of alk‐1‐enyl acyl or diacyl phosphoglycerides in the treated cells. Pentadecan‐2‐one added to the culture medium apparently gains entrance to the cell since both pentadecan‐2‐one and pentadecan‐2‐ol were detected in the ketone‐treated cells and their culture medium.
Cholesterol and repair processes in arteriosclerosis
Authors: Kaunitz Hans
Published: November 2006

The high cholesterol content of the atheroma and the correlation between elevation of the serum cholesterol and myocardial infractions gave rise to the lipid theory of arteriosclerosis, which assumes that cholesterol induces arteriosclerotic lesions and that its reduction counteracts their development. However, many facts contradict this theory. Therefore, a new hypothesis has been based on the high cholesterol content of old pathological lesions of granulomatous nature and the similarity of atheromata to granulomas. In the latter, a complicated tissue containing a high percentage of cholesterol is deposited in response to the injurious agent, which becomes walled off by this tissue. Thus, cholesterol forms part of a protective mechanism, a hypothesis compatible with the known facts about the relationship of cholesterol to arteriosclerosis.
Hyperlipidemia and premature arteriosclerosis
Authors: Smith Frank Rees
Published: November 2006

In the last decade, understanding of the relationship between plasma lipoprotein concentrations and arteriosclerosis has advanced considerably. Prospective and case‐control epidemiologic studies in the general population have established a direct correlation between low density lipoprotein and an inverse correlation between high density lipoprotein concentrations and the risk of coronary disease. Detailed studies of patients and families with genetic hypercholesterolemia, hypertriglyceridemia, and combined hypercholesterolemia hypertriglyceridemia have identified subpopulations at particular risk. Skin fibroblast lines from patients with genetic hyperlipidemias have been used to provide important new information on the regulation by plasma lipoproteins of cellular cholesterol metabolism. We are entering a phase of investigation where epidemiological and biochemical data supplement each other in such a way that the old hypothesis linking plasma lipids to atherosclerosis has new life.
The development of coronary thrombosis following myocardial infarction
Authors: Branwood A. Whitley
Published: November 2006

One hundred twenty‐one patients who died from myocardial infarction were studied. Occlusive coronary artery thrombosis was present in 32%. In 68% of these, the infarct developed first. Factors inducing thrombus formation include fall in systemic blood pressure, alteration of blood flow, shock, and size of infarct. Factors inducing infarction, apart from hypoxia, may be stress, altered cell membrane permeability, and increased catecholamines.
Effect of catecholamines and β‐blockers on linoleic acid desaturation activity
Authors: de Gómez Dumm Irma N. T. , de Alaniz María J. T. , Brenner Rodolfo R.
Published: November 2006

The effect of catecholamines and adrenergic blocking agents on the oxidative desaturation of linoleic acid in rat liver microsomes was studied. Epinephrine (1 mg/kg/body weight) produced a significant decrease on the conversion of [1‐14C]linoleic acid to γ‐linolenic acid. The effect of epinephrine was blocked by single injections of the β blockers propranolol (10 mg/kg body weight) or dichloroisoproterenol 30 min before the hormone treatment. Isoproterenol (100 μg/kg body weight) produced a significant decrease on the activity of the linoleyl‐CoA desaturase. The effect of the catecholamines was postulated to be mediated through β receptors by an enhancement of the intracellular levels of cyclic AMP.
Lipid and alkali extractable fatty acids fromMucor rouxii: Effect of thermal changes in growth environment and age of cells
Authors: Safe S.
Published: November 2006

The lipid levels of the fungusMucor rouxii are affected markedly by both the growth temperature and the age of the cells. Both chloroform‐methanol extractable (fraction I) and alkali extractable (fraction II) fatty acids are present in these cells, and the fraction II/fraction I ratio increased significantly with decreasing growth temperature. This ratio was, however, reasonably constant during the entire growth period at each specific growth temperature. In all cases, the unsaturation index of the fraction II fatty acids was significantly lower than the corresponding value for the fraction I fatty acids. Examination of the unsaturation indeces of the two fractions during the early log‐phase growth period (48 hrs) indicated that the indeces decreased with increasing growth temperature; however, as the age of the cells increased, this relationship changed dramatically. At the end of 144 hrs growth, the unsaturation index for fraction II has reversed its temperature dependance completely, since the index is a maximum at the higher growth temperature. The degree of unsaturation for fraction I is a maximum at 25 C and is lower for cells grown at 15 and 35 C; this relationship is true between 96–144 hr after inoculation.
Lipids of cultured hepatoma cells: IV. Effect of serum and lipid upon cellular and media neutral lipids
Authors: Wood Randall , Falch John
Published: November 2006

Minimal deviation hepatoma 7288C cells were cultured in a modified Swim's medium supplemented with decreasing levels of serum, lipid‐free serum, lipid‐free serum plus fatty acids, and other additives. Cellular and media neutral lipid classes were quantitated, the fatty acids of triglycerides and sterol esters analyzed, and the carbon number distribution of triglycerides determined. Cellular triglyceride biosynthesis virtually was inhibited when the medium was supplemented with bovine serum alone. This inhibition was not observed when the medium was supplemented with fetal calf serum alone or mixtures of fetal calf serum and bovine serum. Cells cultivated on medium supplemented with lipid‐free serum plus palmitic or linoleic acids had much lower levels of free and esterified cholesterol. The fatty acid composition of cellular triglycerides and cholesterol esters differed dramatically from the corresponding media lipid classes. Except when linoleic acid was added to the medium, changes in the media serum and lipid levels had only marginal effects upon the fatty acid composition of cellular triglycerides and cholesterol esters. These data, in conjunction with earlier data that showed the media neutral lipid levels did not decrease during cell growth, indicate that these hepatoma cells utilize little or no serum triglycerides and cholesterol esters. Linoleic acid added to the medium dramatically reduced the level of 18∶1 acids in cellular triglycerides and cholesterol esters. Palmitic acid added to the medium did not change the fatty acid compositions significantly. Comparison of experimentally determined and calculated triglyceride carbon number percentages indicated a random distribution of fatty acids in this glyceride. The fatty acid composition of cellular triglycerides was similar to the composition of the cholesterol esters. The lack of characteristic and distinguishable compositions of these two classes that occur in most normal tissues suggests a loss of specificity in the lipid metabolism of this neoplasm at the class level.
High density lipoproteins, 1978—An overview
Authors: Levy Robert I.
Published: November 2006

High density lipoproteins (HDL) have come of age. For, years it has been fashionable to study HDL as an approach to understanding lipoprotein structure and lipid binding. Available in abundant amounts from normal human plasma, readily separable into its individual lipid and soluble apolipo‐protein components, HDL has provided much information for lipoprotein model building. Suddenly it has been thrust center stage clinically by a host of convincing epidemiologic studies that clearly establishes an inverse relationship between HDL levels and coronary vascular events. Biochemists, clinicians, cardiologists and epidemiologists are simultaneously focusing attention on HDL. Familial High Density Lipoprotein Deficiency (Tangier Disease) has been well described but is poorly under‐stood as a clinical syndrome complex. We have suddenly become aware of how little we understand about HDL's normal ultracentrifugal and apoprotein heterogeneity, about its functional role(s) or the determinant(s) of its concentration in plasma. The relative contributions of the two sites of HDL origin, the liver and intestine, are yet to be determined as are the site(s) of degradation. Awareness of a problem and its importance is the first step toward the solution(s) of the problem.
Bile acids LVII. Analysis of bile acids by high pressure liquid chromatography and mass spectrometry
Authors: Shaw Roger , Elliott William H.
Published: November 2006

Several high pressure liquid chromatographic methods for the separation of conjugated and free bile acids are presented. A mixture of synthetic conjugated bile acids has been separated by reverse‐phase systems consisting of either a Waters Associates' “fatty‐acid analysis” or a μBondapak/C18 column eluted with a mixture of 2‐propanol/potassium phosphate buffer (pH 2.5 or 7.0). The major conjugated bile acids present in the gallbladder bile of obese subjects have been analyzed each in less than 30 min and quantitated with a U.V. detector set at 193 nm. Some of the 5α‐ and 5β‐isomers of conjugated bile salts could be resolved in straight‐phase systems on Corasil II or μPorasil columns. Mass spectra of the conjugated bile acids obtained by electron impact were characteristic of the type of amino acid attached to the side chain, and the number of hydroxyl substituents on the nucleus. Most of the isomers could readily be differentiated by the relative intensities of the fragment ions.
Influence of dietary fiber on bile acid metabolism
Authors: Kritchevsky David
Published: November 2006

Fiber, when fed to animals or man, will generally cause increased excretion of bile acids. The level of bile acid excretion appears to be a function of the structure of the fiber. Fiber binds bile acids and bile salts in vitro. The extent of binding is characteristic for each type of fiber and each substrate. Bile acid binding may be one mechanism of the physiological action of fiber.
The metabolism of dihomo‐γ‐linolenic acid in man
Authors: Stone K. J. , Willis A. L. , Hart M. , Kirtland S. J. , Kernoff P. B. A. , McNicol G. P.
Published: November 2006

Orally adminstered dihomo‐γ‐linolenic acid (DHLA) is well absorbed in man; it appears in blood after ca. 4 hr first as triglyceride ester and later as phospholipid. After sustained‐dosing, DHLA penetrated membrane pools and all phospholipid components but, depending on the dosage, reached a metabolic equilibrium in 4–16 days. Intact plateles do not accumulate arachidonate following DHLA administration, and species differences occur in the capacity of animals to metabolize DHLA to arachidonic acid (AA). The rat appears to be unusual in having a very active hepatic Δ5‐desaturase enzyme system. Potentially antithrombotic changes in platelet function which followed the administration of DHLA to man were accompanied by a siginificant increase in the capacity of platelets to synthesize PGE1. Concomitant increases in PGE2 synthesis do not apparently result from an increased production of AA and suggest that DHLA, or a DHLA metabolite, interferes with the metabolism of AA. Effects on thromboxane and prostacyclin synthesis are being studied.
Cardiac and renal lipases and prostaglandin biosynthesis
Authors: Hsueh Wei , Needleman Philip
Published: November 2006

The tissue phospholipids of isolated Krebs perfused rabbit hearts and kidneys can be efficiently labeled with [14C]arachidonic acid. Subsequent stimulation of the prelabeled organ with hormones or ischemia results in release of [14C] prostaglandins (PG). There is a highly efficient acylation mechanism existing in these perfused organs. Thus, tissue lipase activity can only be quantitiatively assessed by measuring the [14C]arachidonic acid in the venous effluent in the presence of albumin infusion which “traps” the released fatty acid. Two types of tissue lipases appear to exist. One is a highly specific phospholipase which is hormone sensitive, thus selectively liberates [14C]arachidonate (but not [14C]oleate, linoleate, and palmitate) from tissue lipids. The other nonspecifically responds to noxious stimuli such as ischemia and releases all fatty acids (e.g., including arachidonic and oleic acid) from tissue lipids. The hormone sensitive lipase appears to be predominantly localized in the vascular tissue (in hearts and kidney cortex), while nonspecific lipase activity is widely distributed in myocardial cells and renal tubules. Therefore, hormone stimulation elicits tightly coupled PG synthesis in the vasculature which possess both phospholipase and the cyclooxygenase while ischemia induced deacylation in the entire, but the majority of the arachidonic acid released is not converted to PG due to a relative lack of cyclooxygenase activity in myocytes and renal tubules.
Turnover of label from [1‐14C] linolenic acid in phospholipids of coho salmon,Oncorhynchus kisutch
Authors: Parker Robert S. , Selivonchick Daniel P. , Sinnhuber Russell O.
Published: November 2006

Juvenile coho salmon were injected intraperitoneally with [1‐14C] linolenic acid, and sampled at 24, 120, and 240 hr. Liver, heart, and gill lipids were extracted, analyzed, and halflives of individual liver glycerophospholipids and n‐3 fatty acids determined from rates of loss of radioactivity. Incorporation of label into gill was much less than into either heart or liver. Total acyl halflife was shorter for the choline phospholipids than for the ethanolamine phospholipids, as were the halflives of all individual n‐3 fatty acids. Eicosapentaenoic acid (20∶5n‐3) had the shortest halflife in both phospholipids (50–60 hr), while docosapentaenoic acid (22∶5n‐3) and docosahexaenoic acid (22∶6n‐3) had much longer halflives. Specific activities of the shorter chain n‐3 fatty acids were much greater than the longer, more unsaturated homologs at all times, suggesting possible differences in their mechanisms of incorporation into phospholipids. Diacylglycerol analysis indicated that de novo synthesis could be responsible for the incorporation of only a small portion of the labeled long chain fatty acids found in phospholipids. The fatty acid halflives reported here for salmon are in general agreement with those found previously in mammals.
Effect of calcium on absorption of fatty acid by rat jejunum in vitro
Authors: Saunders D. R. , Sillery J.
Published: November 2006

The effect of Ca++ on jejunal osmiophilic particles was studied in a recirculating system which was not contaminated with plasma lipoproteins. An isolated, infused segment of rat jejunum was suspended in a bath of liquid paraffin. Transudate, containing osmiophilic particles, appeared like beads of sweat on the serosal surface, and fell to the bottom of the bath. In the range of 25–38 C, 30 C proved to be optimal for histological preservation of villous architecture. Production of transudate, 20 mg/min/g of jejunum, and transport of [14C] oleate proceeded nearly linearly after the first 30 min. Necrosis of mid‐villus and crypt cells became obvious by light microscopy after one hour. Therefore, transudate was collected between the period of 30–60 min. Shadow casting of transudates, produced when saline was infused, revealed that 86±9 (SD) % of osmiophilic particles was <800 Å in diameter; 13±8% was 800–1000 Å; 0.4±0.5% was 1000–2000 Å. Corresponding values were 58±10, 25±5, and 16±5% when 5 mM [14C] oleate+2.5 mM monoolein was infused; 75% of the transported [14C] appeared in triglyceride. Adding 2 mM Ca++ to the infusion doubled the transport of [14C] triglyceride without increasing particle size further. We conclude that luminal Ca++ increases the absorption of luminal fatty acid by rat jejunum in vitro.
The effects of the hypocholesteremic compound 3β‐(β‐dimethylaminoethoxy)‐androst‐5‐en‐17‐one on the sterol and steryl ester composition ofSaccharomyces cerevisiae
Authors: Field Ruth B , Holmlund Chester E. , Whittaker Noel F.
Published: November 2006

When yeast was grown in the presence of 10−4 M 3β‐(β‐dimethylaminoethoxy)‐androst‐5‐en‐17‐one (DMAE‐DHA), the compound 2,3;22,23‐dioxidosqualene (DOS) accumulated. Total free sterol was reduced by about 30%, whereas almost no steryl esters were found. The same drug at lower concentration (3×10−6 M) caused a slight increase in steryl ester production, and a 24% reduction in free sterol content. The marked accumulation of ergostra‐5,7,22,24(28)‐tetraen‐3β‐ol with 3×10−6 M DMAE‐DHA indicated that the C24–28 reductase is especially sensitive to the action of the drug.
Cholestyramine alters the lipid and energy metabolism of chicks fed dietary medium‐or long‐chain triacylglycerol
Authors: Mabayo Remedios T. , Furuse Mitsuhiro , Murai Atsushi , Okumura Jun‐ichi
Published: November 2006

The effects of cholestyramine, a bile acid binding polymer, on the lipid and energy metabolism of chicks given dietary medium‐chain triacylglycerol (MCT) or long‐chain triacylglycerol (LCT) were investigated. Chicks (from 8 to 17 days of age) were fed diets containing MCT or LCT at 200 g oil/kg diet with or without 2% cholestyramine under equalized feeding conditions. An adjusted LCT diet was formulated in order to supply another group with daily nutrients and dietary metabolizable energy (ME) equal to MCT groups, except for corn starch. ME intakes of chicks given MCT or LCT diets were reduced by cholestyramine; consequently, fat and energy retention was reduced, though the reduction was more drastic in chicks fed LCT. This was caused by a change in amounts of the fecal excretion of fat and bile acids. Cholestyramine enhanced the excretion of octanoic acid (8∶0) in the feces, which suggests that bile acids are needed for 8∶0 absorption. Cholestyramine affects the utilization of dietary MCT and LCT by lowering fat and energy retention in chicks. However, the effect of cholestyramine on MCT utilization was smaller than its effect on utilization of LCT.
Sterol and phospholipid acyl chain alterations inSaccharomyces cerevisiae secretion mutants as a function of temperature stress
Authors: Low Christopher , Parks Leo W.
Published: November 2006

Analyses of free sterol, steryl ester and fatty acid components from yeast secretion mutants indicated that free and esterified sterol remained relatively constant over a growth range of 24 C to 34 C. The saturated fatty acid components (16∶0 and 18∶0) increased while the unsaturated fatty acids (16∶1 and 18∶1) decreased as the growth temperature increased. In secretory mutants, fatty acid composition changes are more pronounced than in the wild‐type strain. A shift toward increased saturated and decreased unsaturated fatty acid was observed when cells were subjected to a 2‐hr temperature upshift to 37 C. Steady‐state fluorescence anisotropy data indicated that modifications to the lipid component of yeast plasma membrane produced lipid thermotropic transitions that were 3 C to 6 C higher in yeast cells subjected to thermal stress.
Relationships between cholesterogenesis, microsomal sterols and HMG‐CoA reductase in the perfused rat liver
Authors: Goh Edward H.
Published: November 2006

The relationships between cholesterogenesis and the activity of HMG‐CoA reductase of microsomes prepared with or without sodium fluoride, and between changes of cholesterogenesis and microsomal sterols were studied in the isolated rat liver perfused with or without oleic acid in the presence of AY‐9944. AY‐9944 inhibits the conversion of 7‐dehydrocholesterol, measured colorimetrically as “fast‐acting” sterols, to cholesterol, measured colorimetrically as “slow‐acting” sterols. The level of “fast‐acting” sterols is used to estimate cholesterogenesis and changes in microsomal sterols. It was observed that the activity of HMG‐CoA reductase of microsomes prepared with or without fluoride reflects the relative changes in cholesterogenesis of the perfused livers. In addition, the amount of “fast‐acting” and “slow‐acting” sterols in microsomes correlates with increases in the activity of HMG‐CoA reductase and cholesterogenesis.
Intercorrelations among plasma high density lipoprotein, obesity and triglycerides in a normal population
Authors: Albrink M. J. , Krauss R. M. , Lindgren F. T. , Von Der Groeben J. , Pan S. , Wood P. D.
Published: November 2006

The interrelationships among fatness measures, plasma triglycerides and high density lipoproteins (HDL) were examined in 131 normal adult subjects: 38 men aged 27–46, 40 men aged 47–66, 29 women aged 27–46 and 24 women aged 47–66. None of the women were taking estrogens or oral contraceptive medication. The HDL concentration was subdivided into HDL2b, HDL2a and HDL3 by a computerized fitting of the total schlieren pattern to reference schlieren patterns. Anthropometric measures employed included skinfolds at 3 sites, 2 weight/height indices and 2 girth measurements. A high correlation was found among the various fatness measures. These measures were negatively correlated with total HDL, reflecting the negative correlation between fatness measures and HDL2 (as the sum of HDL2a and2b). Fatness measures showed no relationship to HDL3. There was also an inverse correlation between triglyceride concentration and HDL2. No particular fatness measure was better than any other for demonstrating the inverse correlation with HDL but multiple correlations using all of the measures of obesity improved the correlations. Partial correlations controlling for fatness did not reduce any of the significant correlations between triglycerides and HDL2 to insignificance. The weak correlation between fatness and triglycerides was reduced to insignificance when controlled for HDL2.
Cholesterol methodology for human studies
Authors: Zak B.
Published: November 2006

A classification and review of the methodology involved in the determination of serum cholesterol for human (or animal) studies are presented. The purpose of both is to enable selection of a technique appropriate for the assay intended with a reasonable understanding of its advantages, disadvantages and limitations. The various methods discussed include direct reaction systems, partial isolation systems and complete isolation systems, as well as screening, reference and definitive procedures. The interferences that could occur are considered, especially those caused by hemoglobin, the turbidity in lipidemia, and bilirubin, as well as interferences caused by optical aberrations and chemical reactants. The various instrumental methods used to determine cholesterol or a substitute determinand such as hydrogen peroxide are discussed, including spectrophotometry, electrochemistry and densitometry of electrophoretically separated proteins.
Conformational analysis of sterols: Comparison of X‐ray crystallographic observations with data from other sources
Authors: Duax William L. , Griffin Jane F. , Rohrer Douglas C. , Weeks Charles M.
Published: November 2006

Crystallographic data on over 400 steroids collected in theAtlas of Steroid Structure provide information concerning preferred conformations, relative stabilities and substituent influence on the interactive potential of steroid hormones. Analysis of these data indicates that observed conformational details are intramolecularly controlled and that the influence of crystal packing forces is negligible. Crystallographic data on the orientation of the progesterone side chain contradict published force‐field calculations. In 84 of 88 structures having a 20‐one substituent, the C(16)−C(17)−C(20)−O(20) torsion angle is between 0° and −46°. The 4 torsion angles that lie outside this range do so because of a 16β‐substituent and not because of crystal packing forces. Not one of the 88 structures is found to have a conformation in which the C(16)−C(17)−C(20)−O(20) torsion angle is within ±15° of the most commonly calculated minimum energy value. The narrow range of side chain conformations seen in very different crystalline environments in the 88 crystal structure determinations and the predictable substituent influence apparent in the data strongly suggest that crystallographically observed conformers seldom deviate from minimum energy positions, regardless of hypothetical broad energy minima, metastable states and small barriers to rotation. The 96 crystallographically independent determinations of the cholestane 17‐side chain show that the chain has 4 principal conformations (A∶B∶C∶D), occurring in the ratio 69∶8∶8∶11. Although the fully extended side chain is clearly the energetically most favored one, in 16 observations of cholesterol itself only 6 are in the extended conformation. Some of the correlated conformational changes in the chains can be rationalized on the basis of model studies, but others apparently result from subtle intramolecular forces. The unsaturated B ring provides another element of flexibility in the structure of cholesterol. The 5‐ene B ring is normally observed in an 8β,9α‐half‐chair conformation. However, in structures containing more than one molecule in the crystallographic asymmetric unit, at least one of the 2 molecules is found to differ significantly from this form. It may be that this inherent flexibility is responsible for the presence of conformationally distinct molecules in the same crystal. The intermolecular interaction observed in the crystal structure of cholesterol and its fatty acid derivatives illustrate the type of interaction between the steroid ring system and hydrocarbon chains that can be expected in membrane bilayers.
15‐hydroperoxyeicosatetraenoic acid inhibits human platelet aggregation
Authors: Vericel E. , Lagarde M.
Published: November 2006

Using human platelets isolated from their plasma, we showed that 15‐hydroperoxy‐eicosatetraenoic acid (15‐HPETE) inhibits platelet aggregation induced either by arachidonic acid or prostaglandin H2 analog. 15‐HPETE does not modify platelet prostaglandin and thromboxane formation from exogenous arachidonic acid but does decrease platelet lipoxygenase activity.
Partial synthesis of [1‐14C]phytanic acid
Authors: Poulos A. , Barone E. , Johnson D. W.
Published: November 2006

[1‐14C] Phytanic acid has been prepared in good yield from the unlabeled acid. Pristanyl iodide, prepared from the latter by a modified Hunsdieker reaction, is converted to the corresponding [14C]‐nitrile by reaction with sodium [14C] cyanide in dimethyl sulphoxide; hydrolysis of the [14C] nitrile yields [1‐14C]phytanic acid. The labeled acid should prove to be a useful substrate for the diagnosis of Refsum's disease.
Enzymic synthesis of 1‐alkyl‐2‐acyl‐sn‐glycero‐3‐phosphorylethanolamine through ethanolaminephosphotransferase activity in the neuronal and glial cells of rabbit in vitro
Authors: Roberti R. , Binaglia L. , Francescangeli E. , Goracci G. , Porcellati G.
Published: November 2006

The transfer of radioactivity from cytidine‐5′‐diphosphate ethanolamine into 1‐alkyl‐2‐acyl‐sn‐glycerophosphorylethanolamine of neuronal and glial cells from adult rabbit brain cortex has been investigated in vitro. The synthesis of 1‐alkyl‐2‐acyl‐sn‐glycerophosphorylethanolamine in both cell populations was stimulated 23–25‐fold by the addition of 6 mM alkylacylglycerol. The neuronal cell‐enriched fraction was found to possess/unit protein a 1.7–1.8‐fold ethanolaminephosphotransferase activity (EC 2.7.8.1), as compared to the glial fraction, when saturating concentrations (6 mM) of alkylacylglycerols were added in the incubation system. The neuronal/glial ratio was 2.6–2.8 in the absence of lipid acceptor or with low concentrations of alkylacylglycerol. Under most favorable conditions, 6.4 and 3.3. nmoles 1‐alkyl‐2‐acyl‐sn‐glycerophosphorylethanol‐amine/mg protein/30 min was obtained for neurons and glia, respectively. Various kinetic properties of the 1‐alkyl‐2‐acyl‐sn‐glycerophosphorylethanolamine synthesizing phosphotransferase activity were found to be similar both in neurons and glia.
Some unusual fatty acids ofRhizobium
Authors: Gerson T. , Patel J. J. , Nixon L. N.
Published: November 2006

A number of unusual fatty acids were identified after isolation fromRhizobium. They include 11‐methyl‐octadec‐11‐enoic, 12‐methoxy‐11‐methyl‐ and 11‐methoxy‐12‐methyloctadecanoic, and 11‐methoxy‐ and 13‐methoxynonadecanoic acids.
Positional analysis of isovaleroyl triglycerides using proton magnetic resonance with Eu(fod)3 and Pr(fod)3 shift reagents: I. Model compounds
Authors: Wedmid Yuri , Litchfield Carter
Published: November 2006

The proton magnetic resonance spectra of isomeric triglycerides of isovaleric and palmitic acids in the presence of the downfield and upfield chemical shift reagents Eu(fod)3 and Pr(fod)3 were studied. The resonance profiles of the γ‐protons on the isovaleroyl chains are distinctive for each of the four possible triglyceride isomers at low shift reagent/triglyceride ratios. With either reagent, the well defined γ‐methyl isovalerate doublets can be used to identify 2‐isovaleroyl and 1,3‐isovaleroyl structures and to analyze isomeric mixtures. This technique will be useful for positional analysis of natural cetacean triglycerides containing isovaleric acid.
Effects of phenobarbital upon bile acid synthesis in two strains of rats
Authors: Cohen B. I. , Raicht R. F. , Nicolau G. , Mosbach E. H.
Published: November 2006

Rats of the Wistar and Sprague‐Dawley strains were injected with sodium phenobarbital (100 mg/kg body wt/day) for 8 days. Fecal bile acid excretion was measured on days 6 and 8 of the experiment, and biliary bile acid composition, hepatic microsomal cholesterol, 7α‐hydroxylase, and 7α‐hydroxy‐4‐cholesten‐3‐one 12α‐hydroxylase were determined at the end of the study. In the Wistar rat, injection of phenobarbital produced a doubling of fecal bile acid output (controls, 5.3 mg/rat/day; treated rats, 10.6 mg/rat/day) and a two‐three fold increase in cholesterol 7α‐hydroxylase. The fecal bile acid output of Sprague‐Dawley rats increased 20% in response to phenobarbital (controls, 9.5 mg/rat/day; treated rats, 11.6 mg/rat/day). The activity of cholesterol 7α‐hydroxylase remained unchanged. In both strains, phenobarbital treatment produced a decrease in the proportion of cholic acid in total biliary bile acids (controls, 85%; treated groups, 65%). This was associated with a decrease of 7α‐hydroxy‐4‐cholesten‐3‐one 12α‐hydroxylase activity by ca. 50%. Biliary cholesterol concentrations were reduced in phenobarbital treated rats of both strains, but liver cholesterol concentrations remained unchanged. The drug produced a 25% increase in liver wt, on the average.
Distribution of fatty acids during germination of cottonseeds
Authors: Joshi A. C. , Doctor V. M.
Published: November 2006

Gas chromatographic determination of the fatty acids in the seeds of cottonseed (Gossypium sp.) showed linoleic, palmitic, oleic, and stearic acids, with linoleic acid being the major component. Changes in the composition of fatty acids during various stages of germination were measured in the cotyledons and in the roots. A decrease in the content of all the fatty acids and an 8‐fold increase in the moisture content of the cotyledons were observed during the 10 days of germination. There were no significant changes in the fatty acid contents of the roots with the exception of those in linoleic acid which increased by 50% during 4–10 days of germination. The possible significance of these changes is discussed.
Carduus nigrescens seed oil—A rich source of pentacyclic triterpenoids
Authors: Madrigal R. V. , Plattner R. D. , Smith C. R.
Published: November 2006

Pentacyclic triterpene alcohols (3%), their acetates (18%), and their long chain fatty acid esters (11%), together with triterpene acids (18%), represent ca. 50% of the oil from the seed and pericarp of the thistleCarduus nigrescens Vill. (Compositae). Along with the usual fatty acids, alkaline hydrolysis of this oil gave triterpene alcohols, some of which were identified by gas chromatography‐mass spectrometry. Composition of the triterpenoid fraction, as indicated by gas chromatography of the corresponding acetates, was: α‐amyrin (6%), β‐amyrin (15%), lupeol plus ϕ‐taraxasterol (3%), erythrodiol (6%), and oleanolic acid (3%). Several components, representing 16% of the oil, were not identified. The content of pentacyclic triterpenoids is the largest found in plant seed oils.
Phosphatidylinositol metabolism during fertilization in the sea urchin egg
Authors: Kamel L. Christopher , Bailey Judy , Schoenbaum Laura , Kinsey William
Published: November 2006

Fertilization of the sea urchin egg results in a transient decline in the amount of phosphatidylinositol (PI) to a level equal to about 50% of that present in the unfertilized egg. This response begins as early as 15 seconds after insemination. The level of PI reaches a minimum at 30 seconds post‐insemination, and returns to the original value between 2 and 5 min later. Pulse labelling studies with32PO4 and [3H]‐inositol showed that the incorporation of these two isotopes into 1‐(3‐sn‐phosphatidyl)‐L‐myoinositol 4,5‐biphosphate [PtdIns(4,5)P2] increased as much as 50% within one minute after insemination. This suggests that at least part of the reduction in PI levels represents the phosphorylation of PI to form PtdIns(4,5)P2. We also found that the production of [3H]‐labelled 1D‐myoinositol 1,4,5 triphosphate [Ins(1,4,5)P3] present in the trichloroacetic acid (TCA) soluble fraction of eggs increased over five‐fold during the first 10 min post insemination. The temporal correlation between the early burst of PtdIns(4,5)P2 and Ins(1,4,5)P3 formation and the transient increase in intracellular free calcium known to occur in the fertilized egg suggest that the production of PtdIns(4,5)P2 and ultimately Ins(1,4,5)P3 may be associated with calcium mobilization within the egg.
Effect of oxalic acid impregnation of chromarods on the separation of phospholipids for determination by the latroscan TLC/FID
Authors: Banerjee A. K. , Ratnayake W. M. N. , Ackman R. G.
Published: November 2006

Phospholipid separations were carried out using Chromarods‐SII impregnated with oxalic acid without interfering with Iatroscan TLC/FID detection and measurement. The resolutions were compared with untreated rods. Oxalic acid impregnated Chromarods gave better resolution of phospholipids, and the separations were more reproducible on a day to day basis compared to untreated Chromarods. A concentration of 0.25 M oxalic acid in acetonitrile, with 15 min of impregnation, followed by 60 min of activation at 110 C, provided the ideal conditions for coating. Three solvent mixtures, viz. CHCl3:MeOH:HAc:H2O (50∶30∶8∶4, v/v/v/v), CHCl3:MeOH:H2O (65∶35∶4, v/v/v), and CHCl3:MeOH:28% NH4OH (70∶30∶2, v/v/v) were tested as developing solvents. CHCl3:MeOH:H2O (65∶35∶4) was found to be the best solvent system. Double development (initially in acetone, followed by CHCl3:MeOH:H2O [65∶35∶4]) is of minor value in improving separations. All the above solvent systems are capable of separating most of the commonly occurring plant phospholipids, except phosphatidylinositol and phosphatidylserine. Both of these phospholipids eluted together on Chromarods‐SII, giving a single peak on the Chromarod, regardless of whether the rods were impregnated with oxalic acid.