bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of diabetes and insulin replacement on the lipid properties of hepatic smooth endoplasmic reticulum
Authors: Holloway Caroline Tobia , Garfield Sanford A. 
Published: November 2006

AbstractThis study is a characterization of the lipid properties of the smooth and rough endoplasmic reticulum (SER, RER) of liver from streptozotocin‐induced diabetic rats. A significant decrease in membrane microviscosity was observed in the SER but not the RER of diabetic rats when compared to that of normal controls. This decrease in SER membrane microviscosity correlated with a decrease in cholesterol/phospholipid ratio of these membranes that could be accounted for solely by a change in the membrane cholesterol content. Changes in phospholipid fatty acyl chain composition were also observed in the SER membranes but these changes were small when compared to the large change in cholesterol content observed. Insulin treatment for only one day did not significantly alter the microviscosity of the SER but after 2, 4 and 6 days of treatment both membrane microviscosity and membrane cholesterol content were restored to values similar to those for normal animals. No significant changes in the RER lipid composition were observed. It is well known that increases in glucose‐6‐Pase (G‐6‐Pase) activity of liver ER membranes are associated with diabetic onset. An increase in the specific activity of G‐6‐Pase was observed in both SER and RER membrane preparations, although the observed increase in the SER membrane is higher. The changes in the G‐6‐Pase activity of the SER membranes were correlated with the alterations in the microviscosity and lipid composition of these membranes. It is postulated that lipid properties of the SER membranes, may contribute to the regulation of G‐6‐Pase activity in that membrane.
Occurrence of mixtures of geometrical isomers of conjugated octadecatrienoic acids in some seed oils: Analysis by open‐tubular gas liquid chromatography and high performance liquid chromatography
Authors: Takagi Toru , Itabashi Yutaka 
Published: November 2006

AbstractAnalytical methods to obtain the detailed compositions of the fatty acids in oils containing more than one conjugated octadecatrienoic acid by open‐tubular gas liquid chromatography (GLC) and by reversed‐phase high performance liquid chromatography (HPLC) were established. Effective GLC separations ofcis,trans,trans‐9,11,13‐octadecatrienoic acid (ctt‐9,11,13–18∶3),ctc‐9,11,13–18∶3,ttc‐9,11,13–18∶3,ttt‐9,11,13–18∶3,ttc‐8,10,12–18∶3, andttt‐8,10,12–18∶3 were obtained with an opentubular column coated with the nonpolar liquid phase OV‐1 using an instrument having all‐glass carrier gas pathways. The HPLC method also gave satisfactory separations for the isomeric conjugated octadecatrienoates on the basis of number of thecis andtrans double bonds. Two or three minor conjugated trienoic acids were found along with the principal conjugated trienoic acid in tung oil, and seed oils of cherry,Prunus sp., Momordica charantia, Trichosanthes anguina, Punica granatum, Catalpa ovata, andCalendula officinalis. The mechanism for the formation of the conjugated trienoic acid mixtures in the seed oils is discussed. TheC. ovata seed oil also containedct andtt‐9,12‐octadecadienoic acids. Thett isomer is presumed to be a precursor ofttc‐9,11,13–18∶3, the main conjugated trienoic acid in this oil.
Sterols and their biosynthesis in some freshwater bivalves
Authors: Popov S. , Stoilov I. , Marekov N. , Kovachev G. , Andreev St. 
Published: November 2006

AbstractA number of free sterols and sterol esters of three freshwater mussels was separated and identified. A slow rate of biosynthesisde novo of sterols was demonstrated inAnodonta cygnea. Injected cholesterol was found to undergo esterification, oxidation, Δ22‐dehydrogenation and C‐24 alkylation. Methyl‐[14C]methionine was proved to be incorporated in C‐24 alkylsterols. Abnormally large amounts of cholesterol injected inA. cygnea were metabolized toward restoration of the normal composition of sterols. This was achieved by intensified metabolism of cholesterol, mainly by conjugation, oxidation and Δ22‐dehydrogenation.
Phospholipids and component fatty acids of the pigeon liver
Authors: Desmeth M. , Vandeputte‐Poma J. 
Published: November 2006

AbstractThe phospholipids from the livers of adult pigeons were separated by thin layer chromatography and the component fatty acids analyzed by gas liquid chromatography. They consisted of 53.0% phosphatidylcholine, 26.3% phosphatidylethanolamine, 8.6% sphingomyelin, 6.3% cardiolipin and 4.8% lysophosphatidylcholine. Phosphatidylethanolamine and phosphatidylcholine were characterized by a high concentration of long‐chain polyunsaturated fatty acids with the highest percentages in the phosphatidylethanolamine. Sphingomyelin contained up to 64.5% saturated acids. About 80% of the fatty acids present in the cardiolipin fraction consisted of linoleic acid. The liver phospholipids had the same composition in lactating as in nonlactating pigeons, but differed in many respects from those available in the crop‐milk.
Effects of ethanol diets on cholesterol content and phospholipid acyl composition of rat hepatocytes
Authors: Smith Thomas L. , Vickers Alison E. , Brendel Klaus , Gerhart Mary J. 
Published: November 2006

AbstractChronic treatment of adult male rats with ethanol liquid diets resulted in alterations in phospholipid and cholesterol contents as well as the acyl composition of phosphatidylethanolamine (PE), phosphatidylinositol (PI)‐phosphatidylserine (PS) mixture, and phosphatidylcholine (PC) of isolated hepatocytes. The influence of ethanol on these lipids was largely dependent on the proportion of dietary fat. Phospholipid and total cholesterol contents were elevated 23 and 27%, respectively, by ethanol when offered in a low‐fat diet (5% corn oil). Only the percentage of arachidonic acid from PI‐PS was significantly reduced in the low‐fat ethanol group. Exposure to a high‐fat (34% corn oil) diet in the presence of ethanol for 4–5 weeks resulted in a significant decrease in arachidonate/linoleate ratios of hepatic PE, PS‐PI and PC, while total phospholipid content remained constant. In the high‐fat, ethanol‐treated group, hepatic cholesterol content was increased 2‐fold. These results suggest that the level of dietary fat plays an important role in determining the effects of chronic ethanol consumption on hepatic cholesterol content and phospholipid acyl composition.
Absorption and distribution of orally administered jojoba wax in mice
Authors: Yaron A. , Samoiloff V. , Benzioni A. 
Published: November 2006

AbstractThe liquid wax obtained from the seeds of the arid‐land shrub jojoba (Simmondsia chinensis) is finding increasing use in skin treatment preparations. The fate of this wax upon reaching the digestive tract was studied.14C‐Labeled wax was administered intragastrically to mice, and the distribution of the label in the body was determined as a function of time. Most of the wax was excreted, but a small amount was absorbed, as was indicated by the distribution of label in the internal organs and the epididymal fat. The label was incorporated into the body lipids and was found to diminish with time.Lipids 17: 169–171. 1982.
Role of steroids and triterpenoids in the growth and reproduction ofPhytophthora cactorum
Authors: Nes W. David , Saunders Gary A. , Heftmann Erich 
Published: November 2006

AbstractThe life cycle ofPhytophthora cactorum, a fungal pathogen unable to epoxidize squalene, is controlled by certain combinations and concentrations of polycyclic isopentenoids normally found in the host plant. Data that lend support to this view are given. The fungus is capable of discriminating between various types and amounts of steroids and triterpenoids in terms of their uptake, metabolism, and effects on growth and reproduction. While certain sterols as well as triterpenoids stimulate growth, onlysterols induce significant oospore production. Steroidal alkaloids and estradiol are fungistatic and inhibit sterol‐induced oospore production. The primary difference in the metabolism of sterols and triterpenoids is that the sterols are converted to both esters and glycosides, whereas the triterpenoids are only esterified. The results demonstrate the importance of sterols and their products, compared to other polycyclic isopentenoids, as promoters of growth and reproduction and suggest that the preference for sterols may have its origin in the adaptation to host‐parasite interactions.
The quantitative analysis of plant sterols
Authors: Knights B. A. 
Published: November 2006

AbstractTwo methods for the quantitative analysis of plant sterols have been described. In the first, cholesterol is used for control of recovery and gas liquid chromatography (GLC) analysis. When cholesterol is present in the sterol mixture, a radioactive standard (usually cholesterol or sitosterol) is used to control recovery, and coprosterol is used to monitor GLC. The methods are exemplified for nitrogenfixing root nodules and for chloroplasts, respectively.
Response ofDrosophila tocis‐ andtrans‐22‐dehydrocholesterol: I. A survey
Authors: Kircher Henry W. , Phariss Rebecca L. , Rosenstein Fumiko U. , Baldwin David , Fogleman James C. 
Published: November 2006

AbstractCis‐ andtrans‐22‐dehydrocholesterol were added to media for 10 species ofDrosophila. Thecis isomer prevented normal maturation of 4 species and thetrans isomer was toxic to 9. These findings were corroborated by tests with 4 representative species on a sterol‐deficient medium under axenic conditions. Addition of cholesterol to the latter overcame the toxicity of thetrans isomer.Trans‐22‐dehydrocholesterol may be acting as a competitive inhibitor in the metabolism of phytosterols to cholesterol or ecdysone by the insects.
Taxonomic implication of sterol composition in the genusChlorella
Authors: Holden Marcia J. , Patterson Glenn W. 
Published: November 2006

AbstractThirty‐five isolates of the genusChlorella were grown under standardized conditions and analyzed for sterol composition. Six different sterol synthetic patterns were found. Two patterns were characterized by nuclear unsaturation at C‐5 and one type by nuclear unsaturation at C‐7. The remaining isolates all synthesize sterols with a diunsaturated nucleus (C‐5+C‐7) with various modifications. Subtype 1 synthesizes only C28 sterols, subtype 2 produces C28 and C29 sterols, and subtype 3 (1 isolate) produces C28 sterols with nuclear unsaturation at C‐5+C‐8 in addition to the Δ5,7 C28 sterols seen in the first 2 subtypes. Comparison of the sterol composition of strains shared in common with taxonomic researchers showed good correlation with the taxonomic scheme of Fott and Novakova which has been confirmed by Kessler and coworkers using other biochemical markers.
The role of squalene synthetase in the inhibition of tetrahymanol biosynthesis by cholesterol inTetrahymena pyriformis
Authors: Warburg Colin F. , Wakeel Marwa , Wilton David C. 
Published: November 2006

AbstractThe biosynthesis of the triterpenoid alcohol tetrahymanol byTetrahymena pyriformis is rapidly inhibited by the addition of cholesterol to the growth medium. The primary site of this inhibition by cholesterol has been established to be at the level of the enzyme squalene synthetase. The protein synthesis inhibitor cycloheximide produces an identical decline in squalene synthetase activity to that of cholesterol and the half‐life of the enzyme is about 50 minutes. No direct inhibition of the enzyme is observed and suggests that cholesterol inhibits the actual synthesis of the enzyme squalene synthetase. Farnesol is accumulated during in vitro incubations derived from cells grown in the presence of cholesterol or cycloheximide.
Microsomal enzymes of cholesterol biosynthesis from lanosterol: A progress report
Authors: Trazaskos James M. , Bowen Wayne D. , Fisher Gary J. , Billheimer Jeffrey T. , Gaylor James L. 
Published: November 2006

AbstractOur principal goal is the complete resolution and reconstitution of the microsomal enzymes of cholesterol biosynthesis. Elucidation of the enzymology has been achieved primarily through dissection of the membrane‐bound, 19‐step multienzymic process. This report describes the dissection approach through both interruption of specific steps and reconstitution of enzymes that catalyze oxidation of the 14α‐methyl group. In earlier work, 4‐demethylation was resolved into 3 component reactions catalyzed by: 4‐methyl sterol oxidase (NAD[P] H‐ and O2‐dependnet); steroid 4α‐carboxylic acid decarboxylase (NAD‐dependent); and 3‐ketosteroid reductase (NADPH‐dependent). The 3‐ketosteroid reductase and decarboxylase have been solubilized with Lubrol WX and deoxycholate, respectively, and characterized. The 4‐methyl sterol oxidase (cytochrome b5‐dependent) recently has been solubilized with Renex 690. This study represents successful elucidation of a microsomal enzyme sequence by interruption of the central 10‐step segment of the multienzymic formation of cholesterol from lanosterol. The initial C‐32 oxidative reaction of 14α‐methyl group elimination is catalyzed by a from of cytochrome P‐450 that is induced by isosafrole. The induced cytochrome P‐450 has been solubilized with Emulgen 913 and purified to homogeneity (17 nmol of cytochrome/mg protein). 24,25‐Dihydrolanosterol is oxidized by combination of cytochrome P‐450 reductase, hematin, NADPH, glutathione, and the purified, isosafrole‐induced cytochrome in an artificial liposome. Oxidation product identification is underway. This study represents successful elucidation of a microsomal multienzymic sequence by solubilization and reconstitution of a segment of the pathway. The remaining enzymes under study are the Δ8→Δ7 isomerase and 3 NADPH‐dependent double bond reductases that catalyze reduction of: Δ7, Δ14‐ Δ24‐sterol double bonds. Purification of these nonoxygenrequiring enzymes is in progress. Resolution of the enzymes has demonstrated unequivocally that cholesterol synthesis via this pathway could not have appeared biologically until membranes containedboth the cytochrome P‐450‐ and cytochrome b5‐electron transport enzymes. Chemically, all enzymic attacks in the formation of cholesterol from lanosterol appear to be initiated on the α‐face of the relatively planar steroids. Thus, considerable genetic pressure must have been needed for the stereospecific clearing of the steroidal α‐face to form the mature membrane component, cholesterol.
Kinetic analysis of plasma VLDL‐TG and VLDL‐remnant‐TG turnover in anesthetized rats
Authors: Bickerstaffe Roy , Lyon Irving , Rostami Hojat , Baker Nome , Elovson John 
Published: November 2006

AbstractWe have estimated the turnover and relative pool sizes of nascent‐VLDL‐TG and VLDL‐remnants‐TG in anesthetized rats. [1‐14C]Palmitoyl‐ and [2‐3H]glyceryl‐labeled “VLDL”‐TG (including nascent VLDL‐TG and VLDL‐remnants‐TG) were prepared by injecting labeled palmitate and glycerol into donor rats. Labeled serum from these rats was then injected intravenously into nembutalized male rats and serial blood samples taken for 30 min. Special care was taken to define any early components in the labeled “VLDL”‐TG disappearance curves. In other experiments, the donors were rendered functionally hepatectomized 30 min after injection of3H‐glycerol and the endogenous labeled VLDL‐TG was allowed to circulate 30–60 min before collection of the TG‐labeled VLDL‐remnants‐containing serum. The latter was injected into 4 recipient nembutalized rats and the remnant‐TG‐turnover measured by serial sampling as above. In two cases,14C‐“VLDL” and3H‐VLDL‐remnants were injected as a single bolus into ether‐anesthetized rats. Despite its complex composition, “VLDL”‐TG in most cases disappeared in a single exponential fashion for 30 min with an average half‐life of 5.9 min in nembutalized and 2.8 in ether‐anesthetized rats. VLDL‐remnants‐TG showed a more complex behavior, but contained a major rapid component with a mean t1/2 of ca. 1.5 min in both groups. The data, analyzed by multicompartmental analysis, were fitted to a simple model in which turnover of a larger nascent VLDL‐TG pool with formation of a more rapidly turning over smaller pool of VLDL‐remnant‐TG is the rate‐limiting step in overall TG removal from the d<1.006 fraction of rat serum. The data are consistent with our theoretical prediction that under these conditions the kinetics of the VLDL‐remnants cannot be resolved from analysis of the total composite “VLDL” (nascent plus remnant) pool.
Lipid and fatty acid composition of the endogenous energy sources of striped bass (Morone saxatilis) eggs
Authors: Eldridge Maxwell B. , Joseph Jeanne D. , Taberski Karen M. , Seaborn Gloria T. 
Published: November 2006

AbstractThe unique physiological flexibility of the early life stages of striped bass is attributed to the calorierich endogenous energy sources of the striped bass egg. Eggs of different aged striped bass from geographically separate populations were examined for lipid and fatty acid compositions and were found to be basically similar. Yolk components of the eggs contained significantly less total lipid than oil globules, were more diverse in lipid class composition and consisted mostly of polar lipids. Oil globules were entirely lipid material consisting predominantly of steryl/wax esters. Fatty acid compositions of yolk and oil globules differed according to their respective lipid compositions. The functional significance of these lipids is discussed in relation to the ecological context of the early life stages.
Bovine pulmonary surfactant: Chemical composition and physical properties
Authors: Yu Sue , Harding Paul G. R. , Smith Norman , Possmayer Fred 
Published: November 2006

AbstractBovine pulmonary surfactant was obtained by endotracheal lavage of lungs from newly slaughtered cows followed by differential centrifugation. Lipid extracts of bovine surfactant contained 3% neutral lipid, mainly as cholesterol and diacylglycerol and 97% phospholipid. Phosphatidylcholine (79%) and phosphatidylglycerol (11%) accounted for most of the phospholipids with smaller amounts of phosphatidyl‐ethanolamine, phosphatidylinositol, lyso‐bis‐phosphatidic, acid and sphingomyelin. Fatty acid analysis revealed high levels of palmitate in phosphatidylcholine and to a lesser extent phosphatidylglycerol, but not in the other diacylphospholipids. Phosphatidylcholine was 53% disaturated and phosphatidylglycerol was 23% disaturated. Monoenoic species accounted for the major proportion of the remaining, lipid. The protein content was 10% as estimated by the Lowry procedure and 5% when determined by amino acid analysis. Extraction with chloroform/methanol removed ca. 90% of the protein but had no effect on the surfactant properties as evaluated by a pulsating bubble technique.
Sterol synthesis from biliary squalene in the jejunal mucosa of the rat in vivo
Authors: Strandberg T. E. 
Published: November 2006

AbstractBecause bile contains substantial amounts of cholesterol precursors, e.g., squalene and differnet methyl sterols, the fate of biliary squalene was studied by incubating isolated jejunal loops of the rat in vivo with bile containing3H‐squalene and14C‐cholesterol. After 90 min, no radioactivity was found in plasma lipids. Closer analysis of gut epithelium revealed that both labeled compounds were preferentially taken up by the villous cells. Biliary3H‐squalene was absorbed almost completely and was further cyclized to free and esterified methyl sterols and cholesterol. Whereas squalene not cyclized to sterols stayed in the mucosa, the newly synthesized sterols were transferred to lumen. The lipid patterns of gut lumen and mucosal cells were quite different, suggesting that the transfer of the newly synthesized lipid to intestinal lumen was not due to the desquamation of epithelial cells alone. The results suggest that biliary cholesterol precursors can contribute to the cholesterol production of the jejunal villous cells bypassing the rate‐limiting step of the cholesterol synthesis pathway, and to the “nonexchanging” fecal neutral sterols of the rat.
Glycolipids and thylakoid proteins in chloroplasts and streptomycin‐bleached lamellae ofEuglena
Authors: Skowronski Gloria A. , Garrigan Owen W. 
Published: November 2006

AbstractThylakoid proteins from (a) the chloroplasts of greenEuglena gracilis cells and from (b) the corresponding concentric lamellar bodies of streptomycin‐bleachedEuglena have been extracted in aqueous sodium dodecyl sulfate (SDS) and purified. The molecular weights of the proteins, determined by polyacrylamide gel electrophoresis in SDS, were 9 kilodaltons for (a) and 9 and 11.5 kilodaltons for the 2 polypeptide chains of (b). Each of the purified proteins consists of 55% apolar and 45% polar amino acids. The lipids of the green and bleached cells differ in polarity of components. Neutral galactolipids are abundant in green cells but not in streptomycin‐bleached cells. Anionic sulfolipid content is greater in the chlorotic organisms. Polyenoic fatty acids, mainly with 16, 18 and 19 carbon atoms, occur in the green cell galactolipids. Cells grown in the presence of streptomycin are, in contrast, rich in monoenes. The opposite is observed in the sulfolipids: monoenes with 16 and 20 carbons are the main fatty acids in the green cells, while a dienoic fatty acid with 12 carbons is found in large amounts in streptomycin‐bleached cultures.
Fatty acid metabolism and cell proliferation: IV. Effect of prostanoid biosynthesis from endogenous fatty acid release with cyclosporin‐A
Authors: Lindsey Jenifer A. , Morisaki Nobuhiro , Stitts Judith M. , Zager Richard A. , Cornwell David G. 
Published: November 2006

AbstractCyclosporin‐A (Cyc‐A) stimulates prostanoid (PGI2) synthesis in confluent smooth muscle cells from guinea pig aorta through the release of endogenous fatty acid. Cyc‐A, like other stimulatory agents for prostanoids, promotes smooth muscle cell proliferation and prostanoid synthesis in these proliferating cells. Indomethacin, a cyclooxygenase inhibitor, and exogenous arachidonic acid block the Cyc‐A effect on cell proliferation.
Sterols from the gorgonianLephogorgia subcompressa
Authors: Rovirosa Juana , Muñoz Orlando , Martín Aurelio San , Seldes Alicia M. , Gros Eduardo G. 
Published: November 2006

AbstractThe free sterols of the gorgonianLephogorgia subcompressa were isolated and characterized by means of gas chromatography (GC) and gas chromatography‐mass spectrometry (GC‐MS) techniques. The mixture contains C27 derivatives as the major sterols besides minor quantities of C26, C28, C29 compounds and also a C30 compound, gorgosterol.
Reduction of hepatic stearoyl‐CoA desaturase activity in rats fed iron‐deficient diets
Authors: Ananda Rao G. , Crane R. Thomas , Larkin Edward C. 
Published: November 2006

AbstractThe effect of feeding iron‐deficient diets to rats on the hepatic stearoyl‐CoA desaturase activity was examined since iron is present in the Δ9 desaturation system. Separate groups of rats were fed low iron diets without fat (FF‐Fe) or containing either 14% hydrogenated coconut oil (HCNO‐Fe) or 14% corn oil (CO‐Fe) for 10 weeks. Diets supplemented with iron (FF+Fe, HCNO+Fe and CO+Fe) were fed to the corresponding control groups. Stearoyl‐CoA desaturase activity in the liver microsomes of rats in the CO+Fe group (2.55±0.17 nmol oleate produced/min/mg protein) was about half of that in the HCNO+Fe (4.76±0.15) and FF+Fe (5.38±0.18) diet groups. In rats which were fed iron‐deficient diets, hepatic desaturase levels were reduced significantly as compared to those of controls (1.0±0.06, CO‐Fe; 2.11±0.13, HCNO‐Fe; 3.65±0.1, FF‐Fe). The hemoglobin (Hb) and hematocrit (Hct) levels in blood showed moderate iron depletion only in the CO‐Fe group. Hence, dietary polyunsaturated fat promotes the onset of iron deficiency. Furthermore, even before the blood Hb and Hct values express iron depletion, the effect of feeding low iron diets was observed by the reduction of hepatic Δ9 desaturase activity in rats fed HCNO‐Fe and FF‐Fe diets.