bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of n−3 fatty acids on the key enzymes involved in cholesterol and triglyceride turnover in rat liver
Authors: Al‐Shurbaji Ayman , Larsson‐Backström Carin , Berglund Lars , Eggertsen Gösta , Bjökhem Ingemar 
Published: November 2006

AbstractThe effect of long‐chain n−3 fatty acids on hepatic key enzymes of cholesterol metabolism and triglyceride biosynthesis was investigated in two rat models. In the first model, rats were intravenously infused for two weeks with a fat emulsion containing 20% of triglycerides in which either n−6 or n−3 fatty acids predominated. The treatment with n−3 fatty acids led to a reduction primarily of serum cholesterol (45%), but also of serum triglycerides (18%). HMG‐CoA reductase activity and cholesterol 7α‐hydroxylase activity were reduced by 45% and 36%, respectively. There were no significant effects on diacylglycerol acyltransferase (DGAT) or phosphatidate phosphohydrolase (PAP) activities. In the second model, rats were fed a diet enriched with sucrose, coconut oil and either sunflower oil (n−6 fatty acids) or fish oil (long‐chain n−3 fatty acid ethyl esters). The treatment with n−3 fatty acids decreased serum triglycerides (41%) and, to a lesser extent, serum cholesterol (17%). Neither glycerol 3‐phosphate acyltransferase (GPAT) or DGAT were affected by n−3 fatty acids. In contrast, PAP activity was reduced by 26%. HMG‐CoA reductase was not significantly affected, whereas cholesterol 7α‐hydroxylase activity was reduced by 36%. The results indicate that part of the TG‐lowering effect of long‐chain n−3 fatty acids may be mediated by inhibition of the soluble phosphatidate phosphohydrolase. The effect on serum cholesterol may be partly due to inhibition of HMG‐CoA reductase.
Hypolipidemic activity of 3‐ and 4‐phenyl‐piperidine‐2,6‐diones and selected N‐substituted derivatives
Authors: Murthy Akula R. K. , Maguire James H. , Alphin Robert S. , Day Patricia A. , Hall Iris H. 
Published: November 2006

AbstractThree‐ and 4‐phenyl‐piperidine‐2,6‐dione derivatives were investigated for hypolipidemic activity at 20 mg/kg/day intraperitoneally in rodents. The 3‐phenyl compound afforded the best activity and effectiveness in both normal and hyperlipidemia‐induced mice. The agent lowered lipids by blocking the de novo hepatic synthesis of cholesterol and triglycerides, specifically at the sites of ATP‐dependent citrate lyase, acetyl CoA synthetase,sn‐glycerol‐3‐phosphate acyl transferase and phosphatidylate phosphohydrolase. The agent caused a more rapid clearance of cholesterol by the fecal route. Cholesterol levels of the chylomicrons, very low density lipoprotein and low density lipoprotein (LDL) were reduced, whereas high density lipoprotein cholesterol was significantly elevated after drug administration. Triglyceride content was lowered in the chylomicron and LDL fractions. These modulations of lipid content of serum lipoproteins by the drug suggest a favorable situation for treatment of hyperlipidemic states.
Regulation of liver cell ganglioside composition by extracellular fluid viscosity
Authors: Yedgar Saul , Reisfeld‐Granot Nutrit , Sela Ben‐Ami 
Published: November 2006

AbstractThe viscosity of plasma and extracellular fluid has been shown to be a regulator of lipoprotein production both in cultured hepatocytes and in vivo. The possibility that this extracellular effect on cell function involves modulation of cell surface membrane components was examined. In the present work, we studied the effect of medium viscosity on liver cell gangliosides known to be involved in various membrane functions and to be located predominantly at the cell surface membrane. Cultivation of isolated hepatocytes as primary cultures markedly reduced the ganglioside content, but this reduction process was attenuated by increasing the viscosity of the culture medium. Elevation of extracellular fluid viscosity inhibited the degradation of the cell gangliosides and secretion of lysosomal enzymes involved in ganglioside degradation. The cellular activity of these enzymes as well as the activity of enzymes involved in ganglioside synthesis, CMP‐NANA:GM1 sialyltransferase, CMP‐NANAP:GM3 sialyltransferase and UDP‐galactose:GD2 galactosyltransferase, were not affected bymodulation of the extracellular medium viscosity. It is proposed that the modulation of cell ganglioside content by extracellular fluid viscosity is due to an effect on enzymes involved in ganglioside catabolism.
New intermediates in the conversion of stigmasterol to cholestanol in the Mexican bean beetle
Authors: Svoboda James A. , Cohen Charles F. , Lusby William R. , Thompson Malcolm J. 
Published: November 2006

AbstractThree intermediates involved in the conversion of stigmasterol to cholestanol in the Mexican bean beetle,Epilachna varivestis, were isolated and identified from an insect for the first time. The three new insect sterols, 22‐stigmastenol, 22,24‐cholestadienol and 24‐cholestenol, were shown to be metabolites of [3H]stigmasterol and accumulated in insect tissues when larvae were fed lima bean leaves coated with azasteroid inhibitors. The side chain metabolism of the ubiquitous phytosterol stigmasterol in the Mexican bean beetle is similar to that in other species that produce cholesterol from C28 and C29 phytosterols; however, the Mexican bean beetle initially reduces the Δ5‐bond and produces mainly cholestanol and lesser amounts of lathosterol as dealkylation products.
New synthesis ofcis‐3,cis‐5‐ andtrans‐3,cis‐5‐tetradecadienoic acids, pheromone constituents ofattagenus elongatulus andA. megatoma
Authors: DeJarlais W. J. , Emken E. A. 
Published: November 2006

AbstractA new method for the synthesis ofcis‐3,cis‐5‐ andtrans‐3,cis‐5‐tetradecadienoic acids, pheromone constituents of the dermestid beetlesAttagenus elongatulus andA. megatoma, was developed. The syntheses are based upon the formation oftrans‐2‐tetradecen‐5‐ynoic acid by reaction of 4‐bromo‐2‐butenoic acid with 1‐decynylmagnesium bromide. The enynoic acid undergoes alkali‐induced isomerization to yield a mixture of acids from whichcis‐3‐ andtrans‐3‐tetradecen‐5‐ynoic acids were separated in 31% and 34% yields, respectively. Methyltrans‐2‐tetradecen‐5‐ynoate was similarly prepared and isomerized to furnish methylcis‐3‐tetradecen‐5‐ynoate in 8% yield. Reduction of the tetradecenynoic acids with dicyclohexylborane gavecis‐3,cis‐5‐andtrans‐3,cis‐5‐tetradecadienoic acids in 4% and 39% yields, respectively. A better yield (49%) in the reduction ofcis‐3‐tetradecen‐5‐ynoic acid tocis‐3,cis‐5‐tetradecadienoic acid was obtained by hydrogenation over Lindlar's catalyst. Similarly, reduction of methylcis‐3‐tetradecen‐5‐ynoate with disiamylborane gave 22% methylcis‐3,cis‐5‐tetradecadienoate.
Fatty acid distribution in the phospholipids ofFrancisella tularensis
Authors: Anderson Robert , Rashid Bhatti A. 
Published: November 2006

AbstractFrancisella tularensis, LVS (live vaccine strain) grown in a chemically defined medium was found to have a lipid content of 21% by dry weight. The two major phospholipids were identified as phosphatidylethanolamine (PE; 76%) and phosphatidylglycerol (PG; 24%) by thin layer chromatographic analysis, staining characteristics and quantitative chemical analyses of fatty acid, phosphate and glycerol constituents. PE contained a high proportion of 24∶0 fatty acid, with lesser amounts of 24∶1, 22∶0 and 10∶0. The major fatty acids of PG were 18∶1 and 22∶0. Hydroxy fatty acids, which are prominent components ofF. tularensis, were conspicuously lacking in these phospholipids; it is therefore concluded that hydroxy fatty acids are constituents of other structures of the organism.
Rice bran oil and hypocholesterolemia in rats
Authors: Sharma R. D. , Rukmini C. 
Published: November 2006

AbstractRats fed rice bran oil at 10% level for a period of eight weeks showed significantly lower levels of total cholesterol, low density lipoprotein and very low density lipoprotein cholesterol, both on cholesterol‐containing and cholesterol‐free diets. High density lipoprotein cholesterol was increased but triglyceride showed a decrease that was not statistically significant. Liver cholesterol and liver triglycerides were also reduced. Fecal excretion of neutral sterols and bile acids was increased after ingestion of rice bran oil.
Selective use of palmitic acid over stearic acid for synthesis of phosphatidylcholine and phosphatidylglycerol in lung
Authors: Tsao Francis H. C. 
Published: November 2006

AbstractThe incorporation of [3H]palmitic acid and [14C]stearic acid into phospholipids in rabbit lung tissue was studied. Under equal molar concentrations of palmitate and stearate, palmitate was incorporated to the 1‐ and 2‐positions of phosphatidylcholine (PC) and phosphatidylglycerol (PG) 2–3 times more than stearate. By contrast, palmitate was 30% less than stearate in phosphatidylethanolamine, phosphatidylinositol and phosphatidylserine. These results suggest that preferential utilization of palmitate over stearate, rather than substrate availability, determines the high content of palmitoyl at the 1‐ and 2‐positions of PC and PG in lung.
Plasma and lipoprotein fatty acid composition in glycogen storage disease type I
Authors: Levy Emile , Letarte Jacques , Lepage Guy , Thibault Louise , Roy Claude C. 
Published: November 2006

AbstractNocturnal intragastric feeding has been shown to be an effective means to improve clinical and biochemical features in glycogen storage disease type I (GSD‐I). In this study, we investigated the fatty acid patterns in a whole plasma and in circulating lipoproteins in patients on this therapy. The results demonstrated massive concentration of total fatty acids coupled with higher levels of triglycerides, free cholesterol, cholesterol ester and phospholipids. This hyperlipidemia involved all fatty acids without distinction of carbon or bond numbers. However, the increase was more pronounced for saturated than polyunsaturated fatty acids, as was demonstrated by the ratios of both oleic acid to linoleic acid (1.91±0.40 vs 0.80±0.09 in controls) and of ω3+ω6 to ω9 fatty acid families (0.92±0.11 vs 1.66±0.08 in controls). The fatty acid patterns in very low (VLDL), low (LDL) and high (HDL) density lipoprotein showed substantial differences in composition, reflecting an association between an abnormal lipoprotein pattern and essential fatty acid deficiency. Furthermore, GSD‐I patients exhibited a significant increase in VLDL (17±2 vs 47±7 mg/dl) and LDL cholesterol (124±7 vs 206±24 mg/dl), coupled with a decrease in HDL cholesterol (49±4 vs 28±3 mg/dl). These data documenting high LDL cholesterol and low HDL cholesterol associated with an increased concentration and proportion of saturated fatty acids suggest that GSD‐I patients on nocturnal intragastric feeding are at high risk for atherosclerosis and its complications.
Electron microscopic cytochemistry of cyclopropenoids in cottonseed (Gossypium hirsutum L.) tissues
Authors: Yatsu Ly , Kircher H. W. 
Published: November 2006

AbstractAn electron microscopic cytochemical procedure for locating cyclopropenoids (CYP) in oilseeds is proposed. The procedure is based on the fact that metallic silver is produced when AgNO3 reacts with CYP. Since so many other compounds react with AgNO3, we treated specimens that do and not contain CYP with AgNO3 and looked for electron‐dense stains that were unique to CYP(+) seeds. Virtually everything in all seed specimens, regardless of the presence or absence of CYP, was stained. However, cottonseeds contained two additional staining constituents not found in controls: (i) certain large, intracellular droplets, and (ii) the cuticles, both occurring exclusively in the axial organs. Extraction of the speciments with ether abolished the stainability of the droplets but did not affect cuticles. Arguments for the validity of the test are presented.
Loss of NADPH during assays of HMG‐CoA reductase: Implications and approaches to minimize errors
Authors: Ness Gene C. , Pendleton Laura C. , Pendleton A. Stacia 
Published: November 2006

AbstractIn assays of 3‐hydroxy‐3‐methylglutary coenzyme A (HMG‐CoA) reductase activity, preincubation of isolated washed microsomes with NADPH led to a time‐ and protein concentration‐dependent, loss of enzyme activity. This occurred despite the presence of an NADPH regenerating system. Addition of fresh NADP, glucose 6‐phosphate and glucose 6‐phosphate dehydrogenase restored activity. Of the individual components, only NADP was effective. Errors due to loss of NADPH are most pronounced in assays using high microsomal protein, low NADPH levels and preincubation with NADPH and when glutathione rather than dithiothreitol is present. To minimize the effects of NADPH depletion, it is recommended that (i) NADP and NADPH not be present during the preincubation period; (ii) incubation periods be relatively short; (iii) microsomal protein concentrations be less than 1 mg; and (iv) NADPH concentrations be 1 to 2 mM.
Analysis of lipids containing hydroxy fatty acids
Authors: Ahmad Fasih , Maier René , Mukherjee Kumar D. , Mangold Helmut K. 
Published: November 2006

AbstractLipids containing hydroxy fatty acids or hydroxyacyl moieties are acetylated with [1‐14C]acetic anhydride or [3H]acetic anhydride, and the content of hydroxy fatty acids or hydroxyacyl moieties is estimated from the specific radioactivity of the acetylated products with respect to that of radioactive standards, such as radioacetylated ricinoleic acid or triricinoleoylglycerol. Mixtures of triacylglycerols containing one, two and three hydroxyl groups per molecule are derivatized in a similar manner, and the resulting acetates are fractionated by thin layer chromatography according to the number of acetate groups per molecule. The relative proportion of each type of triacylglycerols in the mixture is estimated from the distribution of radioactivity in the various fractions. Applications of these techniques are demonstrated by the analysis of several seed lipids.
Medium chain triglycerides and structured lipids
Authors: Babayan Vigen K. 
Published: November 2006

AbstractLipids are an essential component of our body composition and necessary in our daily food intake. Conventional fats and oils are composed of glycerides of long chain fatty acids and are designated as long chain triglycerides (LCT). Body fat as well as the fats and oils in our daily intake fall into this category. In enteral and parenteral hyperalimentation, we can identify such LCT fats and oils. Soy, corn, safflower and sunflowerseed oils are typical of the LCT oils.In the search for alternative noncarbohydrate fuels, medium chain triglycerides (MCT) are unique and have established themselves in the areas of malabsorption syndrome cases and infant care and as a high energy, rapidly available fuel. Structure lipids with a MCT backbone and linoleic acid built into the triglyceride molecule have been developed to optimize the triglyceride structure that is best for patients, particularly the critically ill. Structured lipids with built‐in essential fatty acid components or other polyunsaturated fatty acids promise greater flexibility in patient care and nitrogen support.
Medium chain triglycerides and structured lipids as unique nonglucose energy sources in hyperalimentation
Authors: Mascioli Edward A. , Bistrian Bruce R. , Babayan Vigen K. , Blackburn George L. 
Published: November 2006

AbstractThis brief review will discuss recent work concerning new intravenous lipid emulsions for future use in clinical patients. Intravenous lipid emulsions currently available in the United States are derived from soybean or safflower oils and serve as sources of nonglucose, nitrogen‐sparing calories and the essential fatty acid linoleic acid. Because of concerns that much of the infused long chain triglyceride is not oxidized readily and that there may be some immune system impairment, newer emulsions utilizing medium chain triglycerides have been developed.
Absorption of safflower oil and structured lipid preparations in patients with cystic fibrosis
Authors: Van Hubbard S. , McKenna Mary C. 
Published: November 2006

AbstractPatients with cystic fibrosis (CF) and pancreatic insufficiency usually have decreased linoleic and increased oleic, palmitoleic and eicosatrienoic (20∶3ω9) acids compared to normal values of blood and tissue lipids. These changes are consistent with early essential fatty acid deficiency and are observed despite the regular use of exogenous pancreatic enzyme supplementation. As part of a study to determine the relative role of malabsorption as the etiology for the altered fatty acid status, the change in total plasma fatty acids and in area percent of plasma linoleic acid was determined in CF patients and control subjects following the ingestion of various lipid supplements, including two safflower oil preparations and two structured lipid preparations. Fasting subjects consumed 33 g of lipid in a milkshake containing 15 g of protein and 45 g of carbohydrate. Plasma samples obtained 0, 2, 4, 6 and 8 hr after the meal showed that the CF patients absorbed all preparations when administered with their regular dose of pancreatic enzyme supplement. Comparison of the patterns of increase for total plasma fatty acids and area percent of plasma linoleic acid following the administration of the different lipid supplements in CF patients and control subjects suggests that(a) malabsorption alone is not the cause of the abnormal fatty acid composition in the lipids of CF patients and that increased caloric intake along with consumption of adequate amounts of linoleic acid should improve the linoleic acid status of CF patients; (b) there may be selectively increased metabolism of certain fatty acids from the ingested lipids in the relatively malnourished CF patient compared to control subjects; and (c) conditions favoring the persistence of nonpancreatic lipases seem also to favor absorption and utilization of the structured lipid preparation containing medium chain length fatty acids and linoleic acid in CF patients compared to control subjects.
Medium chain triglyceride in early life: Effects on growth of adipose tissue
Authors: Hashim Sami A. , Tantibhedyangkul Phienvit 
Published: November 2006

AbstractEffects of feeding early in life a diet high in either long chain (LCT) or medium chain triglyceride (MCT) were studied on the development of adipose tissue in post‐weanling rats. The diets were similar in calorie distribution and identical in nutrients except for type of fat. The caloric distribution of the two diets by percent was LCT (corn oil)/protein/carbohydrate, 70/18/12 and MCT/corn oil/protein/carbohydrate, 66/4/18/12. Male littermates with less than 5% weight difference were pair‐fed the two diets randomly at age 18–20 days. One‐fourth of the rats were killed at 10, 16, 22 and 28 weeks of age and analyzed for adipose depots and adipose tissue cellularity. Results showed that the LCT‐fed rats were significantly heavier, with larger epididymal, retroperitoneal, omental and subcutaneous fat pads than the respective pair‐fed MCT rats. Also, LCT‐fed rats had larger size and number of adipocytes than MCT‐fed littermates. It is concluded that the type of fat in the diet, namely LCT or MCT, when fed early in life can influence the development of adipose tissue. MCT appears less lipogenic than LCT. The mechanism for the diminished adiposity of MCT‐fed rats is related to extensive oxidation of MCT and its enhancement of thermogenesis leading to lessened energy efficiency.
The effect of medium and long chain triglyceride on human adipose tissue metabolism
Authors: Katz David P. , Knittle Jerome L. 
Published: November 2006

AbstractStudies have been performed to assess the effects, in vivo and in vitro, of lipid emulsions on human adipose tissue prostaglandin production. Subcutaneous adipose tissue obtained either during elective surgery or by needle aspiration was studied in tissue culture or by using a perifusion apparatus. Physical mixtures of emulsions of long chain triglyceride (LCT) and/or medium chain triglyceride (MCT) were added to the tissue culture medium so that the final concentration was 400 mg/dl. After a 3‐day incubation period the tissue was harvested, placed in buffer and used to determine in vitro production of prostaglandin E2, prostacyclin I2(measured as its stable end product 6‐keto PGF1α) and thromboxane A2(measured as TXB2) by radioimmunoassay. The results demonstrated that samples incubated in 100% MCT had the most significant increase in prostaglandin production, while those incubated in 100% LCT had the most significant decrease in activity of the three prostaglandins assayed. The addition of LCT to MCT caused a stepwise decrease in adipose tissue prostaglandin production. The data suggest a pharmacological rather than a physiological effect of lipid emulsions containing MCT and/or LCT on adipose tissue prostaglandin production. In vivo effects of a 20% safflower oil emulsion, containing high levels of the essential fatty acid linoleate, were assessed in five pediatric patients. Adipose tissue was obtained before and after two and four weeks of treatment. Fatty acid profiles and prostaglandin production were determined. The results demonstrated that intravenous fat infusion increased the concentrations of linoleic and arachidonic acids found in adipose tissue within a short interval. The effect of intravenous fat infusion on human adipose tissue prostaglandin production was less predictable and may have been a function of the patients' disease and subsequent clinical course. These findings suggest that lipid emulsions should not be viewed solely as a source of intravenous energy, because they may have the potential to elicit changes in prostaglandin production as demonstrated by a human adipose tissue model.
Role of brown adipose tissue in thermogenesis induced by overfeeding a diet containing medium chain triglyceride
Authors: Baba Nahla , Bracco E. Filippo , Hashim Sami A. 
Published: November 2006

AbstractThe role of brown adipose tissue in the mechanism of medium chain triglyceride (MCT)‐induced thermogenesis was investigated. Under anesthesia, the interscapular brown adipose tissue (IBAT) was excised in male Sprague‐Dawley rats, and the animals were fitted with gastrostomy tubes. After a 10‐day recovery period, the animals were divided into two groups: one group received a diet containing MCT as 50% of calories, and the other group received an isocaloric diet containing long chain triglyceride (LCT). The diets were fed for 6 wk at a level of calorie intake that was 150% of the ad libitum intake of a parallel control group. During the last week of the study, resting and norepinephrine (NE)‐stimulated O2 consumption and CO2 production were measured in a Noyons diaferometer. At the end of 6 wk, the animals were weighed and killed. The individual fat pads were dissected and weighed, and an aliquot of the right retroperitoneal fat pad was used to measure adipocyte size and number. The results showed that body weight and adipocyte size (but not adipocyte number) were significantly smaller in the MCT‐fed compared to the LCT‐fed animals. Resting as well as maximal NE‐stimulated oxygen consumption values were significantly higher in the MCT‐fed than the LCT‐fed rats. It is concluded that the enhanced thermogenesis induced by MCT persists despite the absence of IBAT and that the phenomenon is likely related to more extensive oxidation of MCT‐in contrast to LCT‐derived fatty acids, thus leading to increased oxygen consumption, enhanced dissipation of energy as heat and diminished efficiency of weight gain and deposition of body fat.