bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis of deuterium labeled cholesterol and steroids and their use for metabolic studies
Authors: Goad L. J. , Breen M. A. , Rendell N. B. , Rose M. E. , Duncan J. N. , Wade A. P. 
Published: December 2006

AbstractA simple method is described for the preparation of [6,7,7−2H3] sterols and steroids. The synthesis starts with a Δ5‐sterol or steroid and involves preparation of the 6‐oxo‐3α,5α‐cyclosteroid, base exchange in the presence of deuterium oxide to introduce two deuteriums at the C‐7 position and sodium borodeuteride reduction of the 6‐oxo group to introduce the third deuterium atom at C‐6. Rearrangement of the [6,7,7−2H3]6α‐hydroxy‐3α,5α‐cyclosteroid then gives the desired [6,7,7‐2H3]‐Δ5 sterol or steroid. [6,7,7−2H3]Cholesterol, [6,7,7−2H3]pregnenolone and [6,7,7−2H3]3β‐hydroxyandrost‐5‐en‐17‐one were synthesized in this fashion and [6,7,7−2H3]progesterone was prepared from the [6,7,7−2H3]pregnenolone. Three examples of the use of these deuchromatography‐mass spectrometry. The chrysophyte alga,Ochromonas malhamensis, was shown to be capable of introducing an extra methyl or ethyl group at C‐24 of the side chain of [6,7,7−2H3]cholesterol to yield brassicasterol and poriferasterol, respectively. The ovary of the echinoderm,Asterias rubens, was demonstrated to metabolize [6,7,7−2H3]progesterone to yield mainly the 5α‐isomers of pregnane‐3,20‐dione and 3β‐hydroxypregnan‐20‐one. However, the 5β‐isomers of these compounds were also detected as minor products for the first time as progesterone metabolites in this animal. Isolated oocytes of the frog,Xenopus laevis, produced a number of metabolites of [6,7,7−2H3]progesterone. In this report, two of them were shown to be 17α‐hydroxy‐pregn‐4‐en‐3,20‐dione and 20α‐hydroxypregn‐4‐en‐3‐one.
Anesthetics may restructure the hydrogen belts of membranes
Authors: Brockerhoff H. 
Published: December 2006

AbstractAnesthetic molecules can form hydrogen bonds or organize hydrogen‐bond networks. It is argued that they affect the neuronal cell membrane not by an amorphous fluidization of the hyprophobic core of the lipid bilayer but by a restructuring of its hydrogen belts, i.e., the regions occupied by the CO and OH groups of the membrane lipids. The structured disturbance of the hydrogen‐bond network is translated latitudinally to hydrogen‐bonding sites of the proteins of the membrane, causing allosteric changes of ion channels that result in neuronal blocking.
The effect of embryological development on phosphatidylethanolamine methyltransferase, phosphatidyldimethylethanolamine methyltransferase and choline phosphotransferase of rabbit liver microsomes
Authors: Cornatzer W. E. , Hoffman Dennis R. , Haning Judy A. 
Published: December 2006

AbstractThe effect of embryological development on the two biosynthetic enzymes involved in phosphatidylcholine biosynthesis in liver microsomes of −12, −9, 0, +4, +14, +36 day old rabbits has been determined. The specific activity (pmol phosphatidylcholine formed/min/mg microsomal protein) of the phosphatidyletanolamine methyltransferase in the liver microsomes is very low before birth and a 33% increase at birth occurs when compared to the‐12 day old fetal livers. The pmol of phosphatidylcholine formed/min/mg protein by the choline phosphotransferase pathway in fetal liver microsomes is 5, 10, 73, 199, 107 and 307 times greater than by the phosphatidylethanolamine methyltransferase pathway for −12, −9, 0, +4, +14, +36 day old rabbits, respectively. The specific activities of the choline phosphotransferase in the liver microsomes increased from the −12 day old fetal livers to 1.6, 19, 73, 39, 27 times for the −9, 0, +4, +14 and +36 day old animals, respectively. The choline phosphotransferase pathway in comparison to the phosphatidylethanolamine methyltransferase pathway is providing the major phosphatidylcholines in the membranes of the endoplasmic reticulum before birth and early fetal development of the rabbit.
Effect of dietary animal and vegetable protein on gallstone formation and biliary constituents in the hamster
Authors: Mahfouz‐Cercone Susan , Johnson James E. , Liepa George U. 
Published: December 2006

AbstractA gallstone‐inducing diet was utilized to examine the effect of dietary proteins (casein, soybean and cottonseed) on gallstone formation. Casein produced gallstones in 100% of the animals; however, soybean or cottonseed proteins reduced gallstone incidence to 32% and 0%, respectively. In an effort to ascertain the mechanisms responsible for gallstone formation, serum cholesterol and the 3 primary biliary constituents (bile acids, phospholipids and cholesterol) were measured. Casein produced a 4‐fold increase in biliary cholesterol, whereas soybean and cottonseed yielded a 3‐and 2‐fold increase, respectively, when compared to a commercial diet (Purina, no. 5001). Serum cholesterol was reduced by substituting dietary vegetable protein for animal protein. This study suggests that substitution of vegetable for animal protein in the diet can decrease gallstone formation in hamsters. It is proposed that this reduced gallstone formation is due to the decreased concentrations of biliary cholesterol induced by dietary modification.
Lipoxygenase inhibition by naturally occurring monoenoic fatty acids
Authors: St. Angelo A. J. , Ory R. L. 
Published: December 2006

AbstractLipoxygenase activity was not detected in preparations from several varieties of rapessed. Erucic acid, one of the main components of rapessed oil, competitively inhibited both soybean and peanut lipoxygenases. Various other long‐chain monoenoic fatty acids were assayed for their effects on lipoxygenase activity with linoleic acid as substrate. Fatty acid chain length, from C16, to C24, was not a significant factor, but position of the point of unsaturation did affect enzyme activity. The position of the double bond from the carboxyl group seemed to be more significant than the distance between the point of unsaturation and the methyl terminal group in terms of inhibition.
The dietary regulation of acyltransferase and desaturase activities in microsomal membranes of rat liver
Authors: Pugh E. L. , Kates M. 
Published: December 2006

AbstractDietary manipulation produces marked alterations in desaturase activities of rat liver microsomes with no concomitant changes in acyltransferase activities. Desaturation of stearoyl‐CoA (Δ9‐desaturase), linoleoyl‐CoA (Δ6‐desaturase), eicosatrienoyl‐CoA (Δ5‐desaturase) and eicosatrienoyl‐phosphatidylcholine (Δ5‐desaturase) was elevated in animals fed a corn oil diet and lowered in those fed a coconut oil diet compared to control animals. The Δ5‐desaturase activities were also lowered in starved animals and elevated in starved animals refed a fat‐free diet. However, no changes in acyl‐CoA:1‐acylsn‐glycero‐3‐phosphocholine acyltransferase activity were observed in the membranes of animals maintained on any of the dietary regimens studied. These observations suggest that the desaturases of rat liver microsomes are regulated independently of the acyltransferases and that desaturation of eicosatrienoyl‐phosphatidylcholine is regulated at the level of the desaturase itself and not by availability of the phospholipid substrate.
Lipids of liver, kidney, spleen and muscle in a case of generalized deficiency of cytochrome b5 reductase in congenital methemoglobinemia with mental retardation
Authors: Hirono Haruko 
Published: December 2006

AbstractThe lipid compositions of liver, kidney, spleen and muscle in a case of generalized deficiency of cytochrome b5 reductase in congenital methemoglobinemia with mental retardation were analyzed and compared with age‐matched controls. The contents of cholesterol and phospholipids (μmol/g) in each organ were within the normal range. Diminished proportions of unsaturated fatty acids were observed in ethanolamine phosphoglycerides (EPG) of the liver. The proportion of linoleic acid decreased to less than half of the normal level in EPG of liver, kidney and spleen.
Diet‐ and hormone‐induced lipid deposition in rat kidney: Correlation with systolic blood pressure
Authors: Fischer G. M. , Swain M. L. , Chacko S. 
Published: December 2006

AbstractThe influence of estradiol on deposition of cholesterol in tissues of ovariectomized rats on normal and high lipid diets was studied. Concomitantly the influence of a contraceptive steroid combination was studied in a similar manner in intact rats. It was found that the high lipid diet resulted in increased deposition of cholesterol in aorta, heart, liver and kidney. The presence of either endogenous or exogenous hormones accentuated the deposition of cholesterol in the kidney and resulted in significantly higher systolic blood pressures in these rats. In the rats on a high lipid diet, the concentration of cholesterol in the kidney correlated positively with systolic blood pressure. It is concluded that estrogen and high lipid diet exert a synergistic effect on deposition of cholesterol in kidney. The positive correlation between kidney cholesterol concentration and systolic blood pressure suggests a possible role for kidney lipid deposition in the hypertensive effect of estrogens.
Growth of a sterol auxotroph derived fromSaccharomyces cerevisiae on chemically synthesized derivatives of cholesterol possessing side‐chain modifications
Authors: Rodriguez R. J. , Arunachalam T. A. , Parks L. W. , Caspi E. 
Published: December 2006

AbstractA number of cholesterol derivatives were analyzed for their ability to satisfy bulk membrane and high‐specificity sparking requirements of a yeast sterol auxotroph (RD5‐R) (Rodriguez, R. J., Taylor, F. R., and Parks, L. W. [1982], Biochem. Biophys. Res. Commun. 106, 435–441). Substitution of hydrogen by bromine or iodine at C‐26 or substitution of C26‐methyl by bromine enabled the resulting sterol to satisfy bulk or sparking functions. The presence of a side‐chain hydroxyl or keto group at C‐25 on a 26‐norcholesterol completely abolished the ability of cholesterol to satisfy either sterol requirement. Growth studies revealed that, while the oxygenated cholesterol derivatives were not growth‐supportive of RD5‐R, they were not growth‐inhibitory.
Fatty acid composition of triglycerides from adipose tissue transplanted between obese and lean mice
Authors: Enser Michael , Ashwell Margaret 
Published: December 2006

AbstractThe subcutaneous adipose tissue of genetically obese mice (ob/ob) differs from that of lean litter‐mates not only by virtue of its larger cells but also in its fatty acid composition; it contains a higher proportion of palmitoleic acid and a lower proportion of linoleic acid. To determine whether these differences in fatty acid composition were inherent in fat cells, subcutaneous adipose tissue from obese and lean mice was transplanted under the kidney capsules of lean and obese host mice and the fatty acid composition of the neutral lipids of the graft and of the host perirenal and subcutaneous fat was determined 1 or 2 months later. The fatty acid composition of grafts from lean donors in obese mice resembled that of the perirenal adipose tissue of the obese hosts after 1 month, with a lower proportion of linoleic acid and a higher proportion of palmitoleic acid than in lean mice. Grafts from obese mice in lean mice had fatty acid compositions which were either unchanged, partially changed or which completely resembled that of the host. The use of grafts prelabeled by feeding the donor margaric acid indicated that total lack of fatty acid turnover, rather than selective metabolic processes, was responsible for the failure of some grafts from obese mice in lean mice to acquire the fatty acid composition of the perirenal adipose tissue of the host.
Effect of dietary fatty acids on Δ5 desaturase activity and biosynthesis of arachidonic acid in rat liver microsomes
Authors: De Gómez Dumm I. N. T. , De Alaniz M. J. T. , Brenner R. R. 
Published: December 2006

AbstractThe effect of different fatty acids supplemented to a fat‐free diet on the activity of Δ5 desaturase was studied. Fat‐free diet produces a reduction in the conversion of eicosa‐8,11,14‐trienoic acid to arachidonic acid. The addition of thecis‐ω6 acids, linoleic, γ‐linolenic or arachidonic to the diet produces an increase of eicosatrienoic acid desaturation, shifting Δ5 desaturase activity towards the controls on a balanced diet. This reactivation is apparently produced by induction of enzyme biosynthesis since linoleate effect was suppressed by simultaneous cycloheximide injection. On the contrary, no changes in Δ5 desaturation activity were found when the diet was supplemented with palmitic or 9‐trans,12‐trans‐linoleic acid. The changes on the activity of Δ5 desaturase were compared with the fatty acid composition of plasma and liver microsomes.
Effect of bile acid feeding on hepatic steroid 12 α‐hydroxylase activity in hamsters
Authors: Kuroki Syoji , Hoshita Takahiko 
Published: December 2006

AbstractThe effects of feeding cholic acid, chenodeoxycholic acid and ursodeoxycholic acid on the activity of the hepatic steroid 12α‐hydroxylase, gallbladder bile acid composition, fecal neutral sterol output, cholesterol synthesis and bile acid synthesis were determined in female hamsters. The 12α‐hydroxylase activity was inhibited to 56% by cholic acid, to 62% by chenodeoxycholic acid, and to 78% by ursodeoxycholic acid compared with the control. Bile acid composition was altered by feeding of cholic acid and chenodeoxycholic acid to be rich in the given bile acids. Fecal neutral sterol output increased about twice by feeding chenodeoxycholic acid and ursodeoxycholic acid, whereas cholic acid had no significant effect. Body cholesterol synthesis increased to 217% by chenodeoxycholic acid and to 274% by ursodeoxycholic acid, whereas effect of cholic acid was not significant. Bile acid synthesis was suppressed to 48% of control only by chenodeoxycholic acid. A positive correlation between the 12α‐hydroxylase activity and the bile acid synthesis was observed in the control, chenodeoxycholatefed and ursodeoxycholate‐fed animals. In conclusion, ursodeoxycholic acid might have less inhibitory effect on the steroid 12α‐hydroxylase and the bile acid synthesis than chenodeoxycholic acid.
Comparison of ultracentrifugation and gel filtration for the isolation of bovine lipoproteins
Authors: Grummer R. R. , Davis C. L. , Hegarty H. M. 
Published: December 2006

AbstractLipoproteins from the plasma of three nonlactating Holstein cows were isolated using either preparative ultracentrifugation or gel filtration chromatography. Lipoprotein classes obtained by ultracentrifugation were very low density plus chylomicra, <1.006 g/ml; low density, 1.007–1.039 g/ml; high density1, 1.040–1.063 g/ml; and high density, 1.064–1.22 g/ml. These lipoprotein classes were individually applied to an agarose gel column to determine at what volume they eluted in comparison to lipoproteins that were separated after applying total bovine lipoproteins to the column. Three major peaks corresponding to very low density lipoproteins plus chylomicra, low density, and high density lipoproteins resulted after gel filtration of total lipoproteins. Very low density lipoproteins plus chylomicra, obtained by ultracentrifugation, eluted as a single peak, as did low density and high density lipoproteins. However, high density1 lipoproteins eluted as two peaks. The first peak eluted at the same volume as low density lipoproteins, and the second peak eluted at a volume similar to that of the ascending slope of the high density lipoprotein peak. Results from disc polyacrylamide gel electrophoresis, immunoelectrophoresis and double immunodiffusion of lipoprotein fractions, and SDS polyacrylamide gel electrophoresis of their apoproteins, similarly indicated that the lipoproteins present in the 1.040–1.063 g/ml density interval are a mixture of low and high density lipoproteins rather than a unique class of lipoproteins.
Metabolism of fatty acid, glycerol and a monoglyceride analogue by rat cardiac myocytes and perfused hearts
Authors: Tamboli Ashlesha , Maten Mary Vander , O'Looney Patricia , Vahouny George V. 
Published: December 2006

AbstractStudies have been conducted on the uptake and metabolism of unesterified fatty acid, free glycerol and 1‐hexadecyl glyceryl ether by rat cardiac myocytes, and of fatty acid, intact triglyceride and the glyceryl ether by perfused rat hearts. Cardiac myocytes efficiently extracted, oxidized and esterified oleic acid, but demonstrated little ability to utilize free glycerol. Although the glyceryl ether was efficiently extracted by myocytes, it was neither hydrolyzed or esterified. The perfused heart also extracted and metabolized unesterified fatty acid, and the fatty acid released during lipolysis of circulating lipoprotein triglyceride. The glyceride glycerol, however, was largely recovered (90%) in the perfusate suggesting inefficient myocardial utilization of either free glycerol or partial glycerides. Myocardial extraction of glyceryl monoether was demonstrated, but the monoglyceride analogue was also unmetabolized by intact heart tissue. The results suggest that if monoglycerides are produced by the action of lipoprotein lipase on circulating triglycerides, reutilization of intact monoglycerides for higher glyceride synthesis is not a major fate of these products.
Effect of specific dietary fatty acids on lipogenesis in the livers and mammary glands of lactating mice
Authors: Abraham S. , Hillyard L. A. , Lin C. Y. , Schwartz R. S. 
Published: December 2006

AbstractThe effects of linoleic, linolenic and columbinic acids fed as 4% of a high carbohydrate (50% glucose) diet on the activities and the amounts of several enzymes associated with fatty acid synthesis in livers and mammary glands of lactating mice were compared with those for stearic and oleic acids. Fatty acid synthesis, measured in vivo, was significantly lower in livers of mice ingesting all 3 polyunsaturated fatty acids (PUFA), whereas in mammary glands synthesis was lower only in mice receiving columbinic acid. The activities of fatty acid synthetase (FAS) and acetyl CoA carboxylase were significantly reduced in liver by all 3 PUFA, as were activities of glucose‐6‐phosphate dehydrogenase, malic enzyme (ME) and citrate cleavage enzyme (CCE), also associated with lipogenesis. In mammary gland, on the other hand, the activities of these enzymes were unaffected by dietary PUFA. The tissue contents of FAS, ME and CCE, measured by rocket immunoelectrophoresis, were found to be significantly reduced in liver by linoleate, linolenate and columbinate but were not significantly altered in mammary gland. The decrease in hepatic lipogenesis observed was principally due to a decrease in the amounts of these enzymes induced by the dietary PUFA but the inhibition in mammary gland caused by columbinate could not be accounted for by a reduction in enzyme contents and therefore may be due to allosteric effects which occur when fatty acid synthesis is measured with3H2O. The fatty acid composition in liver and mammary gland of dams and in liver and kidney of pups completely reflected dietary fatty acids. Columbinate made up ca. 20% of the total fatty acids in both tissues of the columbinic acid‐fed mice and ca. 15% in the pup tissues. This suggests that columbinate is incorporated into milk lipids of dams and is easily absorbed by pups. The elevated ratios of 16/16∶1 and 18/18∶1 in liver and mammary gland of dams and liver and kidney of the pups from dams fed linoleate, linolenate and columbinate suggest that each of these polyunsaturated fatty acids in the diet can inhibit the activity of Δ9 desaturase.
Use of antioxidants in the analysis of vatamins A and E in mammalian plasma by high performance liquid chromatography
Authors: Chow Faye I. , Omeye Stanley T. 
Published: December 2006

AbstractA simple, sensitive, quantitative method for the simultaneous assay of retinol, α‐tocopherol and γ‐tocopherol in rat, guinea pig, monkey and human plasma was developed by using high performance liquid chromatography. It was found that antioxidant was required to stabilize the fat‐soluble vitamins in the plasma of rats. The effect of several antioxidants on the recovery of fat‐soluble vitamins was evaluated. Results showed that 0.125% butylated hydroxytoluene (BHT) in ethanol and 0.025% BHT in heptane yielded recoveries >95% in 0.1 ml plasma.
Immobilized lipoxygenase in continuous production of fatty acid hydroperoxides
Authors: Laakso Simo 
Published: December 2006

AbstractSoybean lipoxygenase‐1 was covalently coupled to agarose with 75% recovery of catalytic activity. Because evidence was obtained that the immobilization resulted in improved operational stability of the enzyme, a lipoxygenase‐reactor and a continuous process for the synthesis of 13‐hydroperoxy‐linoleic acid and 15‐hydroperoxyarachidonic acid were developed. A procedure based on spectrophotometric hydroperoxide assay and constant oxygraphic monitoring of the effluent is presented for the calibration of the reactor to operate at the highest conversion efficiency when oxygenating quantitatively the substrate. Under these conditions, the reactor was capable of producing about 0.6 mg of hydroperoxy fatty acid/1.0 ml of wet gel/hr. The covalently coupled enzyme has been stable during six months of storage at 3 C in 0.2 M Na‐borate buffer, pH 9.0, and during the same period, its operational stability in the column has been unaltered under the conditions used.
Autoxidation of cholesterol fatty acid esters in solid state and aqueous dispersion
Authors: Korahani V. , Bascoul J. , Crastes de Paulet A. 
Published: December 2006

AbstractCholesteryl stearate, oleate, linoleate, linolenate and arachidonate were oxidized in solid form (at 100 C) and in a water dispersion (in the presence of potassium stearate, pH 7.5, 80 C). The unsaponifiable fraction was analyzed by capillary gas liquid chromatography. In the solid state, the oxidation rates of esterified cholesterol were high for stearate and oleate, low for the polyunsaturated esters and very low for free cholesterol. In water dispersion, the rates were reversed, e.g., free cholesterol oxidized more quickly than its stearic and oleic acid esters. The fatty chains in 18∶0 and 18∶1 inhibited the autoxidation of cholesterol. Hydroxylation of the cholesterol side chain only occurred during solid‐state autoxidation as previously observed by others. The 20‐ and 25‐hydroxycholesterols were never detected in the products of micellar reactions, regardless of which surfactant was used for micelle formation.