bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aspects of sterol metabolism in the yeastSaccharomyces cerevisiae and inPhytophthora
Authors: Parks L. W. , McLean‐Bowen C. , Bottema C. K. , Taylor F. R. , Gonzales R. , Jensen B. W. , Ramp J. R. 
Published: November 2006

AbstractUsing 5 wild‐type strains of yeast, nonequivalence in the isolation of sterol mutants was observed. Experiments are described on the effects of sterol modifications on growth, physical and enzymic properties ofSaccharomyces cerevisiae andPhytophthora cactorum. Although discontinuities in Arrhenius kinetics were observed by fluorescence anisotropy and enzymic measurements of mutants (but not wild‐types) of yeast, evidence based on membrane permeability and differential scanning calorimetry failed to support bulk lipid phase transitions as the cause for the discontinuities.
Interception of discrete oxygen species in aqueous media by cholesterol: Formation of cholesterol epoxides and secosterols
Authors: Gumulka Jerzy , Pyrek Jan St. , Smith Leland L. 
Published: November 2006

AbstractThe oxidation products of cholesterol oxidized by different dioxygen species, hydroxyl radical, or triatomic species ozone variously implicated in biological oxidtions are compared. Some products are unique to the oxygen species involved, whereas others, such as the isomeric cholesterol 5,6‐epoxides, are formed broadly by many oxygen species. The resolution of the isomeric cholesterol 5,6‐epoxides by capillary column gas chromatography on SE‐30 or SE‐54 has been achieved.
Utilization and metabolism of dietary sterols in the honey bee and the yellow fever mosquito
Authors: Svoboda James A. , Thompson Malcolm J. , Herbert Elton W. , Shortino Thomas J. , Szczepanik‐Vanleeuwen Patricia A. 
Published: November 2006

AbstractThe honey bee,Apis mellifera, does not convert C28 and C29 phytosterols to cholesterol as found in most previous studies of phytophagous or omnivorous insects, but instead the workers and queens selectively transfer 24‐methylenecholesterol, sitosterol and isofucosterol from their endogenous sterol pools to the brood larvae regardless of the sterol in the worker diet. Administering radiolabeled sterols by feeding and injection has made it possible to trace this selective transfer through a second generation of the honey bee. In further comparative sterol metabolism studies, the yellow fever mosquito,Aedes aegypti, was shown to be capable of dealkylating and converting a radiolabeled C29 dietary sterol ([14C] sitosterol) to cholesterol. Metabolic studies with several radiolabeled dietary sterols and an inhibitor of steroid metabolism in the yellow fever mosquito further verified this capability.
A new route to steroid ring C aromatization from readily available precursors
Authors: Anastasia Mario , Allevi Pietro , Fiecchi Alberto , Scala Antonio 
Published: November 2006

Abstract3β‐Acetoxy‐8α,9α‐epoxy‐5α‐cholest‐14‐ene (1); 3β‐acetoxy‐14α,15α‐epoxy‐5α‐cholest‐8‐ene (2); 3β‐acetoxy‐5α‐cholest‐8(14)‐ene‐9α,15α‐diol (3); and 3β‐acetoxy‐5α‐cholesta‐8(14),9(11)‐dien‐15α‐ol (4) have been aromatized to a 9∶1 mixture of 3β‐hydroxy‐12‐methyl‐18‐nor‐5α,17β(H)‐cholesta‐8,11,13‐triene (5a) and 3β‐hydroxy‐12‐methyl‐18‐nor‐5α,17α(H)‐cholesta‐8,11,13‐triene (5b) in ethanol solution by using hydrochloric acid. The aromatization by action ofp‐toluenesulfonic acid gave mainly the epimer with the natural C‐17 configuration as the acetate 5c at the appropriatep‐toluenesulfonic acid concentration. 3β‐Acetoxy‐5α‐cholesta‐7,9(11),14‐triene (7a) and 3β‐hydroxy‐5α‐cholesta‐8,11,14‐triene (8a), 2 intermediary compounds in the aromatization, were isolated and characterized.
A1H NMR anomaly for steroidal alcohols? Reactions of a steroidal γ‐ketoacid
Authors: Piatak David M. , Ashline Kirk A. , Angelos George , Swenson Rebecca P. , Caspi Eliahu 
Published: November 2006

AbstractThe chemical and spectroscopic properties of several reaction products of 17β‐hydroxy‐1,3‐seco‐2‐nor‐5α‐estran‐1‐oic acid and 17β‐hydroxy‐1,3‐seco‐2‐nor‐4‐oxo‐5α‐estran‐1‐oic acid were examined and found to be atypical. For instance, the methyl ester of the first acid was resistant to basic hydrolysis conditions but partly hydrolyzed with 100% H2SO4. Reduction of the ester by LiA1H4 gave 1,3‐seco‐2‐nor‐5α‐estrane‐1,17β‐diol from which diacetate, ditosylate and 17‐monotosylate derivatives were prepared. The C‐1 methylene protons of each appeared as a singlet in 60, 100 and/or 270 MHz NMR spectra. The methyl ester and the diacetate of the diol were synthesized by alternate methods to verify the assigned structures. A 470‐MHz spectrum eventually resolved the C‐1 methylene protons of the monotysylate into the AB portion of an ABX pattern, further confirming the assigned structures. Also, 2,3‐seco‐1‐oxo‐5α‐estran‐17β‐ol 17‐nitrate was synthesized.
Constituents of human meconium: II. Identification of steroidal acids with 21 and 22 carbon atoms
Authors: Pyrek Jan St. , Sterzycki Roman , Lester Roger , Adcock Eugene 
Published: November 2006

AbstractMonohydroxylated acid fraction isolated from human meconium was found to contain, in addition to C20 and C24 acids identified previously, three C22 bile acids‐(20S)‐3α‐hydroxy‐23,24‐bisnor‐5β‐cholan‐22‐oic, (20S)‐ and (20R)‐3β‐hydroxy‐23,24‐bisnor‐chol‐5‐en‐22‐oic, and one C21 acid‐3β‐hydroxypregn‐5‐en‐21‐oic. These compounds were identified by capillary gas chromatography‐mass spectrometry and by comparison with standards. It is postulated that these C22 acids, as well as the two monohydroxylated C24 bile acids (lithocholic and 3β‐hydroxychol‐5‐enoic) are produced in the maternal intestine by microbial flora and transferred to the fetus through the placenta.
Unusual urinary cholesterol metabolites following intracerebral injection of [4‐14C]cholesterol into rats: I. The minor14C‐metabolite
Authors: Ramsey R. B. , Nicholas H. J. 
Published: November 2006

Abstract[4‐14C] Cholesterol injected intracerebrally into 10–12‐day‐old rats becomes localized largely in central nervous system myelin. If sufficient14C is injected, myelin cholesterol remains labeled for the rest of the rats' lives. In the course of the slow myelin cholesterol turnover that ensues, a unique series of cholesterol metabolites is excreted exclusively in the rats' urine. There is reason to believe that the metabolites are formed in the cental nervous system before entering the urine. This manuscript describes separation of the 2 urinary14C‐labeled metabolic types and isolation and identification of the minor14C‐labeled material which consists of cholesterol and 2 other sterols bound covalently to short‐chain peptides. The minor sterols have been tentatively identified as 24‐ and 26‐hydroxycholesterol. The sterol‐peptide combinations have been isolated from human male urine, also.
Modulation of prostaglandin synthesis in rat peritoneal macrophages with ω‐3 fatty acids,
Authors: Magrum Linda J. , Johnston Patricia V. 
Published: November 2006

AbstractIn view of the findings that ω3 fatty acids inhibit the synthesis of prostaglandins (PG) from arachidonic acid (20∶4ω6) and that among immunologically active cells, the macrophage, is a major producer of PG, we undertook a study of the effect of dietary α‐linolenic acid (18∶3ω3) on PG synthesis in the macrophage. Rats were fed purified diets containing either 10% corn oil (CO) or linseed oil (LO), providing either a low (1/32) or high (3.5/1) ratio of 18∶3ω3 to 18∶2ω6, respectively, for 6 weeks. Fatty acid analysis of macrophage phospholipids showed that there was an appreciable increase in the percentage of ω3 fatty acids and a decrease in the ω6 fatty acids in macrophages from rats fed the LO diet. The changes in fatty acid composition were associated with a significant decrease in the synthesis of prostaglandin E (PGE) by macrophages from rats fed the LO diet. Macrophages from rats fed the 2 dietary, oils did not differ in their ability to degrade PG, thus the difference in PG production appeared to be a consequence of decreased synthesis only. The dietarily induced changes in PGE synthesis were readily overcome in vitro by culturing macrophages with complexes of fat‐free bovine serum albumin and either 20∶4ω6 or 20∶5ω3.
Metabolism of platelet‐activating factor by blood platelets and plasma
Authors: Alam Iftekhar , Smith J. Bryan , Silver Melvin J. 
Published: November 2006

AbstractHigh performance liquid chromatography in combination with a radioactivity detector was used to study the metabolism of platelet‐activating factor (1‐0‐alkyl‐2‐acetyl‐sn‐glycero‐3‐phosphocholine) by washed platelets, platelet‐free plasma and platelet‐rich plasma obtained from rabbits and humans. Degradation of platelet‐activating factor in plasma was completely inhibited by diisopropylfluorophosphate and was partially inhibited by ethylenediamine tetraacetic acid. Washed platelets metabolized platelet‐activating factor not only to the 2‐lyso compound but also, by reacylation of this lyso intermediate, to an analogue of platelet‐activating factor probably containing a long‐chain acyl group at thesn‐2 position. These transformations occurred, but to a lesser extent, in platelet‐rich plasma.
The effect of AY‐9944 on yeast sterol and sterol ester metabolism
Authors: Pereira Ravi , Holmlund Chester E. , Whittaker Noel 
Published: November 2006

AbstractThe effects of the hypocholesterolemic drug AY‐9944 (trans‐1,4‐bis(2‐chlorobenzylaminoethyl)cyclohexane dihydrochloride) at two concentrations (10−4M and 5×10−4M), on the synthesis of sterols and sterol esters bySaccharomyces cerevisiae were investigated. Although growth was not markedly affected by the drug, there was a decrease in the free sterol to sterol ester ratio with increased drug concentration. A concomitant increase in the saturated fatty acids esterified to sterol relative to the unsaturated fatty acids was also noted in response to increased drug concentration. Ergosterol accounted for 94.7% of the free sterol in the control culture and for 87.8% of the 5×10−4M drug‐treated culture, respectively. However, in the sterol ester fraction, the ergosterol content decreased from a value of 45.1% in the control culture to 2.4% in the 5×10−4M AY‐9944 treated culture. The sterol ester fraction simultaneously showed increased levels of the Δ8 sterol, fecosterol, in response to increased drug concentration from a 7.4% control value to 57.4% in the 5×10−4M drug‐treated culture. The accumulation of the Δ8 sterol suggests that the site of action of the drug is probably at the Δ8 to Δ7 isomerase step in the biosynthesis of ergosterol. The fact that ergosterol is retained as the major free sterol suggests a biological advantage to the retention of this particular sterol. In addition, the near normal growth in the presence of the drug, in spite of the occurrence of an altered sterol ester profile, indicates that the composition of the sterol ester fraction is not as critical as the free sterol fraction.
Human low density lipoprotein structure: Correlations with serum lipoprotein concentrations
Authors: Nelson Charles A. , Morris Manford D. 
Published: November 2006

AbstractHuman low density lipoproteins (LDL) were isolated and purified from individuals having widely differing serum lipid concentrations. Very low density lipoproteins (VLDL) and high density lipoproteins (HDL) were also isolated and quantitated. HDL2 and HDL3 were separated by flotation velocity in the analytical ultracentrifuge and their relative weight percent determined. The mean density of LDL from 41 individuals was determined by flotation velocity at two different solvent densities. The mean density of LDL was directly proportional to the triglyceride (r=0.65) and VLDL (r=0.50) concentrations and inversely proportional to the HDL (r=−0.55) and HDL2 (r=−0.74) concentrations (all significant at P<0.001). The mean molecular weight of LDL from 42 individuals was determined by flotation equilibrium centrifugation. The mean molecular weight of LDL was directly proportional to the HDL (r=0.49) and HDL2 (r=0.48) concentrations and inversely proportional to the serum triglyceride (r=−0.60) and VLDL (r=−0.48) concentrations (all significant at P<0.005 except triglyceride—P<0.001). The molecular weight of LDL was inversely proportional to its density, and thus inversely proportional to its protein/lipid ratio which was confirmed by composition measurements. The density and molecular weight of LDL had no relationship to the concentration of LDL (r=0.04 and 0.03).
How do polyunsaturated fatty acids lower plasma cholesterol levels?
Authors: Horrobin David F. , Manku Mehar S. 
Published: November 2006

AbstractFor 30 years it has been known that linoleic acid can lower elevated cholesterol levels. Large increases in linoleic acid have been widely recommended as a way of reducing the risk of cardiovascular disease. Such recommendations have resulted in major dietary shifts in some countries, including the USA. Yet the precise characteristics of the linoleic acid molecule which confer on it cholesterol‐lowering properties are unknown. γ‐Linolenic acid, the first essential fatty acid metabolite of linoleic acid, has been found to have cholesterol‐lowering actions ca. 170 times greater than the parent molecule, suggesting that linoleic acid must be converted to γ‐linolenic acid to exert its desirable effects on cholesterol metabolism. Aging, sex, diabetes mellitus, alchol, catecholamines andtrans fatty acids and saturated fats can all modulate the Δ‐6‐desaturase enzyme which converts linoleic acid to γ‐linolenic acid. This provides a possible unifying explanation for the actions of these known risk factors for cardiovascular disease.
The effect of developing solvents on lipid class quantification in chromarod thin layer chromatography/flame ionization detection
Authors: Parrish C. C. , Ackman R. G. 
Published: November 2006

AbstractUndeveloped lipids on Chromarods give peaks of variable shape and of variable area when scanned through the flame ionization detector (FID). With a brief exposure to developing solvents of suitable polarity, it is possible to produce sharp peaks of less variable area without appreciably moving peak axes. Longer developments or developments in more polar solvent systems result in broader‐based peaks of lower area. These observations, based on many analyses of a triglyceride and of a ketone, suggest that the FID response of lipids can be modified according to their distribution around or along Chromarods.
Multiscale modeling and simulation of nanotube-based torsional oscillators
Authors: Xiao Shaoping , Hou Wenyi 
Published: November 2006

Abstract
In this paper, we propose the first numerical study of nanotube-based torsional oscillators via developing a new multiscale model. The edge-to-edge technique was employed in this multiscale method to couple the molecular model, i.e., nanotubes, and the continuum model, i.e., the metal paddle. Without losing accuracy, the metal paddle was treated as the rigid body in the continuum model. Torsional oscillators containing (10,0) nanotubes were mainly studied. We considered various initial angles of twist to depict linear/nonlinear characteristics of torsional oscillators. Furthermore, effects of vacancy defects and temperature on mechanisms of nanotube-based torsional oscillators were discussed.
Stabilizing polymorphic transitions of tristearin using diacylglycerols and sucrose polyesters
Authors: Oh Jun‐Hyun , McCurdy Alan R. , Clark Stephanie , Swanson Barry G. 
Published: November 2006

AbstractThe polymorphic transitions of synthesized tristearin in the presence of selected DAG or commercial sucrose polyesters (SPE) were investigated using DSC and X‐ray diffractiometry. The stabilizing effects of DAG and SPE on α to β transitions of tristearin were dependent on the chemical structures of additives such as FA chain length, saturation of FA, positions and number of FA on backbones. The addition of 1,2‐distearin (DS) or SPE containing 70% stearic acid with a hydrophile‐lipophile balance value of 1 (S‐170) to tristearin resulted in a significant stabilizing effect on the α to β transition during constant heating and storage of α forms at 53°C. The addition of 1,2‐DS or S‐170 also stabilized the β′ to β transitions of tristearin during constant heating and storage at 59°C. The addition of S‐170 exhibited greater stabilizing effects than the addition of 1,2‐DS during early stages of storage of α or β′ forms of tristearin. This study provides evidence of potential uses for SPE as additives to improve the quality and shelf life of foods containing fats by stabilizing the desirable α or β′ forms of fats.
Performance of two color scales for virgin olive oils: Influence of ripeness, variety, and harvest season
Authors: Melgosa M. , Huertas R. , Hita E. , Roa J. M. , Heredia F. J. , Alba J. , Moyano M. J. 
Published: November 2006

AbstractThe purpose of this investigation was to compare the performance of the bromthymol blue (BTB) method and the Uniform Oil Color Scale (UOCS) method with different sets of virgin olive oil samples from Andalusia (Spain), namely, 1213 samples from olives at three stages of ripeness, 1008 samples from eight olive varieties, and 1700 samples from olives harvested in four different crop seasons. All oils were extracted in the laboratory by the same procedure. The performance of the two color scales was compared using CIELAB color differences between the oil samples and the nearest standard from each scale. The UOCS performed at least 2.0 times better than the BTB for each of the three stages of olive ripeness, and the difference between the two color scales was statistically significant (P<0.001). The UOCS performed at least 1.3 times better than the BTB for each of the eight olive varieties studied, and the differences between the two color scales were statistically significant (P<0.02). The UOCS also performed at least 1.6 times better than the BTB for each of the four harvests analyzed, and the differences between the two color scales were statistically significant (P<0.001). Using the current oil samples, we could discern no substantial improvements to the UOCS standards.
Effect of storage on the original pigment profile of spanish virgin olive oil
Authors: Gallardo‐Guerrero Lourdes , Gandul‐Rojas Beatriz , Roca María , Mínguez‐Mosquera Ma Isabel 
Published: November 2006

AbstractThe present study was carried out on 12 virgin olive oils to determine whether one year's storage under mild conditions of 15°C and darkness affected the initial pigment composition of recently extracted virgin olive oil. Although the total pigment content remained constant, the individual contribution of each pigment changed. The acid compounds liberated from the fruits during the oil extraction process promote the beginning of chlorophyll pheophytinization and the isomerization of the 5,6‐epoxide groups of the minor xanthophylls. During the first 3 mon of storage, there was a generalized increase in pheophytinization that was different for each oil (P<0.01, Duncan test) but was not correlated with the free acidity measured in them. At the same time, isomerized xanthophylls and allomerized pheophytins increased slightly. Following this stage, pyropheophytin a (a pigment not present in the initial oils), was detected; its concentration increased during storage. There were no significant differences in the final percentages of pyropheophytin a among the 12 oils, and the concentration of this new compound represented around 3% of the chlorophyll fraction. The pheophytin a/pyropheophytin a ratio always exceeded 20. All these small pigment transformations were signs that the oil had been stored. The content and class of pigments present in virgin olive oil are authentic indicators of its history prior to marketing.
Interprovenance variation in the composition of Moringa oleifera oilseeds from Pakistan
Authors: Anwar Farooq , Ashraf Muhammad , Bhanger Muhammad Iqbal 
Published: November 2006

AbstractInterprovenance variation was examined in the composition of Moringa oleifera oilseeds from Pakistan. The hexane‐extracted oil content of M. oleifera seeds harvested in the vicinity of the University of Agriculture, Faisalabad (Punjab, Pakistan), Bahauddin Zakariya University (Multan, Pakistan), and the University of Sindh, Jamshoro (Sindh, Pakistan), ranged from 33.23 to 40.90%. Protein, fiber, moisture, and ash contents were found to be 28.52–34.00, 6.52–7.50, 5.90–7.00, and 6.52–7.50%, respectively. The physical and chemical parameters of the extracted M. oleifera oils were as follows: iodine value, 67.20–71.00; refractive index (40°C), 1.4570–1.4637; density (24°C), 0.9012–0.9052 mg/mL; saponification value, 177.29–184.10; unsaponifiable matter, 0.60–0.83%; color (1‐in. cell), 1.00–1.50 R+20.00–30.00Y; smoke point, 198–202°C; and acidity (% as oleic acid), 0.50–0.74. Tocopherols (α, γ, and δ) accounted for 114.50–140.42, 58.05–86.70, and 54.20–75.16 mg/kg, respectively, of the oils. The induction periods (Rancimat, 20 L/h, 120°C) of the crude oils were 9.64–10.66 h and were reduced to 8.29–9.10 h after degumming. Specific extinctions at 232 and 270 nm were 1.80–2.50 and 0.54–1.00, respectively. The major sterol fractions of the oils were campesterol (14.13–17.00%), stigmasterol (15.88–19.00%), β‐sitosterol (45.30–53.20%), and Δ5‐avenasterol (8.84, 11.05%). The Moringa oils were found to contain high levels of oleic acid (up to 76.00%), followed by palmitic, stearic, behenic, and arachidic acids up to levels of 6.54, 6.00, 7.00, and 4.00%, respectively. Most of the parameters of M. oleifera oils indigenous to different agroclimatic regions of Pakistan were comparable to those of typical Moringa seed oils reported in the literature. The results of the present analytical study, compared with those for different vegetable oils, showed M. oleifera to be a potentially valuable oilseed crop.
A process for the preparation of food‐grade rice bran wax and the determination of its composition
Authors: Vali Shaik Ramjan , Ju Yi‐Hsu , Kaimal Thengumpillil Narayana Balagopala , Chern Yaw‐Terng 
Published: November 2006

AbstractA two‐step method was developed for the preparation of food‐grade wax. The first step involved the solventdefatting of crude wax, which gave a dark brown, dry, powdered wax with a m.p. of 75–79°C. The major impurity in the defatted wax was the dark brown resinous matter. In the second step, the resinous matter was removed by bleaching with sodium borohydride in isopropanol. This step yielded a pale yellow, odorless wax with purity higher than 99% and with a m.p. of 80–83°C. The resinous matter was a mixture of aliphatic aldehydes, fatty alcohols, and FA. High‐temperature GC analysis of the purified rice bran wax indicated that it contained 11 major and 9 minor types of saturated wax esters. The major and minor peaks contained C44–C64 and C45–C59 wax esters, respectively. Rice bran wax was mainly a mixture of saturated esters of C22 and C24 FA and C24 to C40 aliphatic alcohols, with C24 and C30 being the predominant FA and fatty alcohol, respectively. The alcohol portion of the wax esters also contained small amounts of branched and odd carbon number fatty alcohols.