bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of buffer constituents on rat liver 3‐hydroxy‐3‐methyl glutaryl coenzyme A reductase
Authors: Srikantaiah M. V. , Noble N. , Orenstein L. , Morin R. J. 
Published: December 2006

AbstractRat liver microsomes prepared in Tris buffer exhibited 3 to 10 times higher 3‐hydroxy‐3‐methyl glutaryl CoA reductase specific activity than microsomes prepared with potassium phosphate buffer. This higher activity was observed in rats killed during mid‐light cycle, but microsomes from rats killed during mid‐dark cycle showed no significant difference in enzyme activity between buffers. When microsomes prepared in the 2 different buffers were preincubated with ATP and MG++, enzyme activity was inhibited to the same extent. The cytosol fraction in each of the 2 different buffer preparations possessed similar phosphatase activity. The higher 3‐hydroxy‐3‐methyl reductase activity in Tris buffer, therefore, does not appear to be due to differences in phosphorylation or dephosphorylation activity.
Lipoproteins of fetal and newborn calves and adult steer: A study of developmental changes
Authors: Forte Trudy M. , Bell‐Quint Julia J. , Cheng Fenny 
Published: December 2006

AbstractSerum lipoproteins in fetal and newborn calves were characterized and compared with those of adult animals. Fetal calf serum contains only low density (LDL) and high density (HDL) lipoproteins; the LDL is the major lipoprotein class. Fetal LDL are ca. 26.0 nm diameter and are morphologically unusual in that particles form linear aggregates or “chains” in which LDL have flattened, parallel sides. These particles contain only apolipoprotein B and are high in polar lipids. Fetal HDL consist of 8.2‐nm, round particles which contain large amounts of chlesteryl ester thus suggesting an active lecithin: cholesterol acyltransferase system in the fetal state. The major protein in fetal HDL is apolipoprotein A−I (80%); however, another component with a molecular weight (MW) of ca. 9,000 is also present. Newborn calves show a 5‐fold increase in HDL concentration. These particles are 9.0 nm spherical particles and they contain mainly apolipoprotein A−I although C‐apolipoproteins are also present; the lipid and apolipoprotein composition of newborn HDL is similar to that of adults. Newborn calves possess very low density (VLDL) lipoproteins which have a mean diameter of 61 nm and are similar in size and composition to those of adult animals; their apolipoprotein composition is principally apolipoprotein B, although C‐apolipoproteins and apolipoprotein A−I are also present. The LDL of neonatal and adult animals are similar in morphology, chemical composition and apolipoprotein content. In both instances, LDL are round particles ca. 19.0 nm diameter which contain less polar lipids than the fetal animal. Apolipoprotein B is the major protein in newborn LDL, but adult LDL additionally contains a protein of 27,000 MW which probably represents apolipoprotein A−I from overlapping α‐migrating particles in this region. The altered morphology and composition of fetal LDL, together with the lack of VLDL, suggest that the LDL particles may be synthesized de novo.
Lactoperoxidase‐catalyzed lodination of arachidonic acid: Formation of macrolides
Authors: Boeynaems J. M. , Reagan D. , Hubbard W. C. 
Published: December 2006

AbstractIn the presence of iodide and hydrogen peroxide, lactoperoxidase catalyzed the conversion of arachidonic acid into several iodinated products; the major one was previously identified as an iodo‐δ‐lactone. Two minor and less polar products have now been characterized as 15‐iodo‐14‐hydroxyeicosatrienoic acid, ω‐lactone and 14‐iodo‐15‐hydroxyeicosatrienoic acid, ω‐lactone, on the basis of125I incorporation, mass spectrometry, proton magnetic resonance spectroscopy and chemical modifications.
Photosensitized oxidation of methyl linoleate: Secondary and volatile thermal decomposition products
Authors: Frankel E. N. , Neff W. E. , Selke E. , Weisleder D. 
Published: December 2006

AbstractStudies of photosensitized oxidation of methyl linoleate show that the greater relative concentration of 9‐ and 13‐hydroperoxides than 10‐ and 12‐hydroperoxides is characteristic of singlet oxygenation and not due to either simultaneous autoxidation or type 1 photosensitized oxidation. Cyclization of the internal 10‐ and 12‐hydroperoxides accounts for their lower relative concentrations. Secondary products separated by silicic acid and high pressure liquid chromatography were characterized spectrally (IR, UV,1H‐NMR,13C‐NMR, GC‐MS). Major secondary products included diastereomeric pairs of 13‐hydroperoxy‐10,12‐epidioxy‐trans‐8‐octadecenote (I and III) and 9‐hydroperoxy‐10,12‐epidioxy‐trans‐13‐octadecenoate (II and IV); minor secondary products included hydroperoxy oxy genated and epoxy esters. Thermal decomposition of the hydroperoxy cyclic peroxides produced hexanal and methyl 10‐oxo‐8‐decenoate as major volatiles from I and III and methyl 9‐oxo‐nonanoate and 2‐heptenal from II and IV. Hydroperoxy cyclic peroxides may be important sources of volatile decomposition products of photooxidized fats.
The effect of environmental temperature on sebum composition in tropical and temperate breeds of cattle
Authors: O'Kelly J. C. , Reich H. P. 
Published: December 2006

AbstractThis study compared the effect of environmental temperature on sebum composition in 2 breeds of cattle, British (SH) and Brahman (GB), which differ in their abilities to tolerate heat. By long‐term exposure of both breeds to environmental temperatures of 24 C and 32 C and the more heat‐tolerant GB breed to 38 C, it was possible to make breed comparison at (a) different body temperatures, i.e, when all animals were exposed to the same environmental temperature, and (b), at the same body temperature, i.e., when the 2 breeds were exposed to different ambient temperatures. The composition of sebum excreted to saturation level on the skin surface was determined. At the same body temperatures, the amounts of fatty acids in each lipid class were higher in GB than in SH animals except during hyperthermia when the amounts of triglyceride fatty acids were similar in both breeds. The total amounts of individual fatty acids except 14∶1, 16∶1, 20∶0 and 14∶OH were higher in both breeds at 32 C than at 24 C. The GB cattle excreted more essential fatty acids (EFA) than the SH cattle at 24 C and at 32 C. There was a significant genotype by environment interaction in the amounts of EFA partitioned between triglycerides and wax esters; in GB cattle, the amount of EFA excreted in triglycerides decreased whereas the amount excreted in wax esters increased with rising body temperature.
Volatile hydrocarbons from photosynthetic membranes containing different fatty acids
Authors: Sandmann Gerhard , Böger Peter 
Published: December 2006

AbstractA cell‐free plant system was developed generating short‐chain volatile hydrocarbons as markers of light‐induced copper‐mediated peroxidation of fatty acids present either as endogenous constituents of photosynthetic membranes or added exogenously. Different polyunsaturated fatty acids are present in the blue green algaeAnacystis nidulans, Anabaena variabilis andSpirulina platensis. The first species has no polyunsaturated acids. Thylakoids isolated from these algae produce different short‐chain volatile hydrocarbons. The location of the double bond of dienoic or higher polyunsaturated fatty acids most distant from the carboxyl group determines the chain length of hydrocarbons evolved. Their number of C‐atoms is the same as found beyond this double bond of the fatty‐acid molecule (ω‐1). This pattern of volatile hydrocarbons produced is in contrast to thermolytic cleavage. Malondialdehyde is formed only when at least 3 double bonds are present in the fatty acid. Peroxidation of endogenous thylakoidal and added fatty acids is completed within 24 hr; a maximum of 1% of the carbon skeleton can be recovered as volatile hydrocarbons.
Lung phosphatidylcholine and fasting in male and female rats
Authors: Abe Masao , Endo Makoto , Nagai Hiroshi 
Published: December 2006

AbstractLung from male and female rats fasted for 4 days were used. Phospholipid, phosphatidylcholine and its molecular species were analyzed in lungs from these rats and effects of fasting upon the biosynthesis of phosphatidylcholine in lungs from both sexes were determined using radioactive choline. The molecular species of phosphatidylcholine in both male and female rats did not differ with fasting except the monoenoic species. Incorporation of choline into phosphatidylcholine in both male and female rats significantly increased after fasting, but distribution of radioactivity in phosphatidylcholine yielded similar values in each group. These results suggest that the decrease of saturated phosphatidylcholine content after fasting may be not due to specific change in saturated phosphatidylcholine.
Reactivity of key metabolic sterols in standard colorimetric assays for cholesterol
Authors: Sarkar Chitta P. , Cenedella Richard J. 
Published: December 2006

AbstractThe reaction of lanosterol, desmosterol and 7‐dehydrocholesterol, key intermediates in cholesterol biosynthesis, were‐compared with cholesterol in 3 standard colorimetric assays for cholesterol based on formation of chomogens with acetic anhydride, ferric chloride and ferrous sulfate. Marked differences in the reaction of the sterols in the different assays were due both to formation of chomogens with qualitatively similar spectral patterns but with greatly different extinctions and to formation of chromogens with clearly different absorption maxima. For example, in all assays, cholesterol and desmosterol formed chromogens with very similar absorption spectra but with varying extinctions, whereas the lanosterol chromogen in all assays was different from cholesterol's in both absorption maxima and in extinctions. The findings show that attempts to measure tissue sterol levels by colorimetric methods can result in great errors when cholesterol is not the sole sterol. Also, the unique spectral properties of the lanosterol chromogen formed in the Liebermann‐Burchard reaction (a sharp absorption peak at 450 nm) suggests the possible use of this method as a qualitative test for lanosterol.
High performance liquid chromatography and glass capillary gas chromatography of geometric and positional isomers of long chain monounsaturated fatty acids
Authors: Svensson Lennart , Sisfontes Leslie , Nyborg Göran , Blomstrand Rolf 
Published: December 2006

AbstractPositional and geometrical isomers of monounsaturated long chain fatty acids were analyzed by the combination of high performance liquid chromatography (HPLC) and glass capillary gas chromatography (GC). A preparative group separation ofcis andtrans isomers of the monounsaturated fatty acid methyl esters was achieved according to chain length by reversed‐phase HPLC, and using a highly sensitive interference refractive index detector. After collection of the different fractions containingcis andtrans forms of the monounsaturated fatty acid methyl esters, the fractions were analyzed for their content of positional isomers using glass capillary GC with Silar‐5 CP as stationary phase. The preparative step in the HPLC was also used analytically for the determination of the ratio between thecis andtrans monounsaturated fatty acids. A comparison was made between the results obtained with the HPLC technique and the results of a GLC technique with a packed OV‐275 column. There was a good correlation between the 2 techniques with a tendency to highertrans values with the HPLC technique (4%). It was shown with reference substances that 18∶1ω6‐cis to ω11‐cis and 18∶1ω5‐trans to ω12‐trans, the most common monounsaturated fatty acid isomers in partially hydrogenated vegetable oils, could be almost quantitatively recovered in the HPLC step. Most of the individual positional isomers of monounsaturated fatty acids of varying chain length could be separated and determined in the glass capillary GC step with the exception of those isomers containing the double bond in a relatively high ω‐position. The relative standard deviation of the technique as determined with reference substances was better than 4%. The described technique was applied to the analysis of the isomeric monounsaturated fatty acid content in partially hydrogenated vegetable and marine oils, and about 5 samples a day could be executed.
Chemical synthesis and spectroscopic characteristics of C18 1,2‐disubstituted cyclopentyl fatty acid methyl esters
Authors: Rojo Jose A. , Perkins Edward G. 
Published: December 2006

AbstractThe chemical synthesis of methyl 9‐(2′‐n‐butylcyclopentyl)nonanoate and methyl 10‐(2′‐n‐propylcyclopentyl)‐decanoate was performed using a Wittig reaction between 2‐alkylcyclopentanones and the corresponding ω‐carbomethoxyalkyl triphenylphosphonium bromides. The intermediate alkylcyclopentylidene alkanoate esters were isolated from the reaction mixture, characterized by spectrometric methods, and then catalytically hydrogenated to the desired cyclopentyl esters. Gas chromatographymass spectrometry (GC‐MS) showed that the final products contained a mixture oftrans‐ andcis‐ring isomers with small amounts of other cyclic by‐products. The GC‐retention features, the mass fragmentation pattern, and the spectroscopic characteristics of both the final and the unsaturated intermediate products are discussed.
The effect of a fish oil diet on the fatty acid composition of individual phospholipids and eicosanoid production by rat platelets
Authors: Careaga‐Houck Mónica , Sprecher Howard 
Published: December 2006

AbstractWhen rats were fed a diet containing chow or fish oil for six weeks, the platelet phospholipid content and percent distribution were similar. In the fish oil fed animals there was a 54, 40, 41, and 24% reduction, respectively, in the levels of 20∶4(n−6) in the choline‐, ethanolamine‐, inositol‐and serine‐containing glycerophospholipids. Dietary fish oil increased the total (n−3) polyunsaturated fatty acid content in all lipids. This effect was most pronounced in the ethanolamine glycerophospholipids which now contained 26, 11, and 4 nmols of 20∶5(n−3), 22∶5(n−3), and 22∶6(n−3) in 109 cells. Ionophore A23187 stimulation of platelets from the chow fed rats resulted in the synthesis of 7, 64, and 3.5 nmols of 12‐hydroxy‐5,8,10‐heptadecatrienoic acid, 12‐hydroxy‐5,8,10,14‐eicosatetraenoic acid and 12‐hydroxy‐5,8,10,14,17‐eicosapentaenoic acid, respectively, from 1×109 cells. The values from animals fed fish oil were 4, 18, and 27 nmol/109 platelets. It was not possible to detect any lipoxygenase products from 22∶5(n−3) or 22∶6(n−3), even though both acids are readily metabolized by lipoxygenase when added directly to platelets. These findings suggest that 22‐carbon (n−3) fatty acids are not liberated when phospholipases are activated by calcium mobilization.
Cholelithiasis in hamsters: Effects of cholic acid and calcium on gallstone formation
Authors: Cohen Bertram I. , Matoba Naoyuki , Mosbach Erwin H. , Stenger Richard J. , McSherry Charles K. 
Published: December 2006

AbstractDietary cholic acid (0.1%) and/or calcium (2.6% as calcium carbonate) were added to a semipurified diet containing cholesterol and ethynyl estradiol to determine whether the incidence of pigment and/or cholesterol gallstones would be changed. Male golden Syrian hamsters were fed the experimental diets for 96 days (Group 1, control; Group 3, cholic acid plus calcium) or only an average of 60 days (Group 2, 0.1% cholic acid). Animals in Group 2 became ill (weight loss, low food intake, diarrhea) possibly due to cholic acid (or deoxycholic acid) toxicity. Cholesterol gallstones and crystals were absent in all experimental groups. The incidence of pigment gallstones was: control, Group 1, 12/16; 0.1% cholic acid, Group 2, 3/13; and 0.1% cholic acid plus calcium, Group 3, 11/22. Cholic acid with or without calcium produced an elevation of both liver and plasma cholesterol: Group 2, 80.1 mg/g and 501 mg/dl; Group 3, 103.7 mg/g and 475 mg/dl vs Group 1, 65 mg/g and 209 mg/dl, respectively. The lithogenic indices of the bile were lower in Groups 2 and 3 compared to Group 1, controls, 0.45 and 0.58 vs 1.16, respectively. The extent of the portal tract pathology could not be correlated with the presence or absence of pigment gallstones or with the levels of lithocholic acid in the hamster bile. In summary, when semipurified diets were supplemented with ethynyl estradiol and cholic acid, with and without calcium supplementation, no cholesterol gallstones formed and the incidence of pigment gallstones was not altered.
Influence of dietary fat composition on intestinal absorption in the rat
Authors: Thomson A. B. R. , Keelan M. , Garg M. L. , Clandinin M. T. 
Published: December 2006

AbstractOmega‐3 fatty acids influence the function of the intestinal brush border membrane. For example, the omega‐3 fatty acid eicosapentaenoic acid (20∶5ω3) has an antiabsorptive effect on jejunal uptake of glucose. This study was undertaken to determine whether the effect of feeding α‐linolenic acid (18∶3ω3) or EPA plus docosahexaenoic acid (22∶6ω3) on intestinal absorption of nutrients was influenced by the major source of dietary lipid, hydrogenated beef tallow or safflower oil. Thein vitro intestinal uptake of glucose, fatty acids and cholesterol was examined in rats fed isocaloric diets for 2 weeks: beef tallow, beef tallow + linolenic acid, beef tallow + eicosapentaenoic acid/docosahexaenoic acid, safflower oil, safflower oil + linolenic acid, or safflower oil + eicosapentaenic acid/docosahexaenoic acid. Eicosapentaenoic acid/docosahexaenoic acid reduced jejunal uptake of 10 and 20 mM glucose only when fed with beef tallow, and not when fed with safflower oil. Linolenic acid had no effect on glucose uptake, regardless of whether it was fed with beef tallow or safflower oil. The jejunal uptake a long‐chain fatty acids (18∶0, 18∶2ω6, 18∶3ω3, 20∶4ω6, 20∶5ω3 and 22∶6ω3) and cholesterol was lower in salfflower oil than with beef tallow. When eicosapentaenoic acid/docosahexaenoic acid was given with beef tallow (but not with safflower oil), there was lower uptake of 18∶0, 20∶5ω3 and cholesterol. The demonstration of the inhibitory effect of linolenic acid or eicosapentaenoic acid/docosahexaenoic acid on cholesterol uptake required the feeding of a saturated fatty acid diet (beef tallow). These changes in uptake were not explained by differences in the animals’ food intake, body weight gain or intestinal weight. Feeding safflower oil was associated with an approximately 25% increase in the jejunal and ileal mucosal surface area, but this increase was prevented by combining linolenic acid or eicosapentaenoic acid/docosahexaenoic acid with safflower oil. Different inhibitory patterns were observed when mixtures of fatty acids were present together in the incubation medium, rather than in the diet: for example, when 18∶0 was in the incubation medium with 20∶4ω6, the uptake of 20∶4ω6 was reduced, whereas the uptake was unaffected by 18∶2ω6 or 20∶5ω3. Thus, (1) the inhibitory effect of eicosapentaenoic acid/docosahexaenoic acid on jejunal uptake of glucose, fatty acids and cholesterol was influenced by the major dietary lipid, saturated (beef tallow) or polyunsaturated fatty acid (safflower oil); and (2) different omega‐3 fatty acids (linolenic acid versus eicosapentaenoic acid/docosahexaenoic acid) have a variable influence on the intestinal absorption of nutrients.
Influence of omega‐3 and omega‐6 fatty acid sources on prostaglandin levels in mice
Authors: Dan Henderson C. , Black Homer S. , Wolf John E. 
Published: December 2006

AbstractStudies from this laboratory, employing a hairless mouse model, have indicated that a polyunsaturated fatty acid source rich in omega‐3 (n−3) fatty acid (FA) inhibits ultraviolet (UV)‐carcinogenic expression, when compared to that of diets containing predominantly n−6 fatty acids. Omega‐3 FA is a poor substrate for cyclo‐oxygenase, the rate‐limiting step in prostaglandin (PG) synthesis—the latter, particularly PGE2, are known to influence tumor biology. Based upon this rationale, plasma and cutaneous PGE2 levels were determined from hairless mice fed diets containing either 4% or 12% corn or menhaden oil. After two weeks on the respective diets, plasma PGE2 levels of corn oil‐fed animals were approximately 6‐fold greater than those of the menhaden oil‐fed groups. A similar response was found in the dermis. Although the relationship to carcinogenic expression is unknown, dietary n−3 FA content can have a pronounced effect upon PGE2 levels and possesses the potential for influencing other immunomodulators.
The combined effects of dietary proteins and fish oil on cholesterol metabolism in rats of different ages
Authors: Choi Yong‐Soon , Ikeda Ikuo , Sugano Michihiro 
Published: December 2006

AbstractMale Sprague‐Dawley rats at the ages of four weeks and nine months were fed purified diets containing 20% proteins either as casein (CAS), milk whey protein (WHY), or soybean protein (SOY) with 5% sardine oil for four weeks. The hypocholesterolemic effect of SOY was not statistically evident as compared to milk proteins at both ages, although serum cholesterol tended to be low in the SOY groups. A significant agedependent increase in serum cholesterol was observed in all dietary groups. Liver cholesterol concentrations were comparable in young rats, whereas in adults they were significantly lower in the SOY than in the CAS or WHY groups. At both ages, the activity of liver 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase tended to be higher in the SOY than in the other groups. Fecal steroid excretion was significantly higher in rats fed SOY than those fed either CAS or WHY, especially in adult rats. Significant age‐ and dietary protein‐effects were observed in fatty acid profiles of liver microsomal phospholipids. Thus, the effects of dietary proteins on various lipid parameters were essentially maintained even when fish oil served as the source of dietary fat.
Fatty acid composition of umbilical arteries and veins: Possible implications for the fetal EFA‐status
Authors: Hornstra G. , van Houwelingen A. C. , Simonis M. , Gerrard J. M. 
Published: December 2006

AbstractFatty acid compositions were determined of phospholipids, isolated from umbilical arteries and veins, obtained from Dutch neonates after vaginal delivery, terminating normal pregnancy. The fatty acid profiles of the cord vessels were characterized by the absence of eicosapentaenoic (timnodonic) acid, a low (2–3%) content of linoleic acid and reasonable amounts of arachidonic acid (10–15%) and docosahexaenoic (cervonic) acid (3–5%). Significant amounts of Mead acid (1–4%) and its direct elongation product (0.5–2%) were also observed. In each cord, the efferent blood vessels contained significantly more Mead acid and other fatty acids of the oleic acid (n−9) family and less fatty acids of the linoleic (n−6) and linolenic (n−3) families than the afferent blood vessel. This indicates that the essential fatty acid (EFA) status of ‘downstream’ neonatal tissue may be marginal. No signs of EFA‐deficiency were observed in endothelial and smooth muscle cells in culture, or in blood vessels from adults. In all cords 22∶5(n−6) was significantly higher in the artery compared to the vein, whereas for all other (n−6) fatty acids this difference was negative. Since the synthesis of 22∶5(n−6) is known to be stimulated when the required amount of cervonic acid, 22∶6(n−3), is too low, our observations also suggest that the cervonic acid status of the neonates investigated was not optimal. Further studies are in progress to relate these findings to maternal EFA status and complications of pregnancy.