bluuebunny/crossref_metadata_2025_split huggingface dataset:
High density lipoproteins, 1978—An overview
Authors: Levy Robert I. 
Published: November 2006

AbstractHigh 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

AbstractSeveral 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

AbstractFiber, 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

AbstractOrally 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

AbstractThe 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

AbstractJuvenile 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

AbstractThe 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

AbstractWhen 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

AbstractThe 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

AbstractAnalyses 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

AbstractThe 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

AbstractThe 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

AbstractA 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

AbstractCrystallographic 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

AbstractUsing 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

Abstract[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

AbstractThe 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

AbstractA 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

AbstractThe 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

AbstractRats 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.