Milk triglycerides from dairy cows abomasally infused with increasing amounts of high-oleic sunflower fatty acids.

The triglyceride composition of milk fat largely determines the manufacturing characteristics of products containing milk fat. Increasing oleic acid content of milk fat might be desirable for human nutrition and also for butter and whipping cream, among other product applications. The objective of this research was to determine the effects of increasing intestinally available oleic acid (provided via abomasal infusion) on the profile of milk triglycerides. A control and 4 increasing doses of free fatty acids from high oleic sunflower oil (HOSFA) were infused into the abomasum of 4 lactating dairy cows in a changeover experimental design with periods of 7 d. Treatments were (1) control (no fatty acids infused), (2) HOSFA (250 g/d), (3) HOSFA (500 g/d), (4) HOSFA (750 g/d), and (5) HOSFA (1,000 g/d). All treatments included meat solubles and Tween 80 as emulsifiers. Infusion of HOSFA increased oleic acid and decreased short- and medium-chain fatty acids in milk fat. Statistical analysis of results showed linear changes in most of the milk triglycerides analyzed. The most significant changes as the result of increasing HOSFA infusion were a decrease in triglycerides with saturated fatty acids (butyrin-caprylin-palmitin, butyrin-laurin-olein, butyrin-myristin-palmitin, butyrin-palmitin-palmitin, caproin-myristin-palmitin, butyrin-palmitin-stearin, caproin-palmitin-palmitin) and an increase in dioleyl triglycerides (with butyric, lauric, myristic and palmitic acids) and triolein. The synthesis of triglyceride is position-specific and does not follow a random distribution model.

Responses to increasing amounts of high-oleic sunflower fatty acids infused into the abomasum of lactating dairy cows.

Increasing the oleic acid (18:1 cis-9) content of milk fat might be desirable to meet consumer concerns about dietary healthfulness and for certain manufacturing applications. The extent to which milk fat could be enriched with oleic acid is not known. Increasing the intestinal supply of polyunsaturated fatty acids decreases dry matter intake (DMI) in cows, but the effects of oleic acid have not been quantified. In a crossover design, 4 multiparous Holstein cows were abomasally infused with increasing amounts (0, 250, 500, 750, or 1,000 g/d) of free fatty acids from high-oleic sunflower oil (HOSFA) or with carrier alone. Continuous infusions (20 to 22 h/d) were for 7 d at each amount. Infusions were homogenates of HOSFA with 240 g/d of meat solubles and 11.2 g/d of Tween 80; controls received carrier only. The HOSFA contained (by wt) 2.4% 16:0, 1.8% 18:0, 91.4% 18:1 cis-9, and 2.4% 18:2. The DMI decreased linearly (range 22.0 to 5.8 kg/d) as the infused amount of HOSFA increased. Apparent total tract digestibilities of dry matter, organic matter, neutral detergent fiber, and energy decreased as the infusion increased to 750 g/d and then increased when 1,000 g/d was infused. Digestibility of total fatty acids increased linearly as infused fatty acids increased. Yields of milk, fat, true protein, casein, and total solids decreased quadratically as infused amounts increased; decreases were greatest when 750 or 1,000 g/d of HOSFA were infused. Concentrations of fat and total solids increased at the higher amounts of HOSFA. The volume mean diameter of milk fat droplets and the diameter below which 90% of the volume of milk fat is contained both increased as HOSFA infusion increased. Concentrations of short-chain fatty acids, 12:0, 14:0, and 16:0 in milk fat decreased linearly as HOSFA increased. The concentration of 18:1 cis-9 (19.4 to 57.4% of total fatty acids) increased linearly as HOSFA infusion increased. Concentrations of 18:1 cis-9 in blood triglyceride-rich lipoproteins increased linearly as infusion increased, whereas contents of 14:0, 16:0, 18:0, total 18:1 trans, and 18:2n-6 decreased linearly. The composition and physical characteristics of milk fat can be altered markedly by an increased intestinal supply of 18:1 cis-9, which could influence processing characteristics and the healthfulness of milk fat. However, an increased supply of free 18:1 cis-9 to the intestine decreased DMI and milk production.

Esterification of dehydroepiandrosterone by human plasma HDL.

Evidence for metabolic esterification of dehydroepiandrosterone (DHEA) in human blood plasma, identification of the active lipoprotein (LP) subclass involved, namely HDL3, as well as positive identification of the long-chain fatty acid esters of DHEA formed as incubation products is presented. The esterification reaction of DHEA and subsequent transfer and transport of DHEA esters in human plasma appears to proceed in a manner similar to that of cholesterol. The experiments presented serve as a model predicting similar metabolic transformations during HDL3 interactions with other steroid hormones that have the delta 5-3 beta-hydroxy steroid ring structure and exhibit nonequilibrium associations with HDL. These observations imply that significant quantities of DHEA, particularly in the conjugated ester form, can enter cells via the membrane receptor-mediated pathways of LP internalization.

In vivo and in vitro pharmacokinetics and fate of furaltadone in meat- and milk-producing animals.

The metabolism of furaltadone was examined by an in vitro hepatic study in cows and goats and an in vivo study in goats using 14C-labeled and unlabeled drug. The half-life of furaltadone was 13 min in the homogenates of caprine and bovine liver and 35 min in the in vivo study of the goat. Less than 2% of the parent drug was present in the urine of animals dosed either intravenously or intramammarily. No furaltadone was detected in the milk after 24 h. Overall, the parent compound was rapidly absorbed, distributed, and widely degraded in the lactating goat. The compound, labeled at the 2-formyl carbon of the furan ring, had a radioactivity recovery of 81% in the feces and urine. Of the total radioactivity, 99.4% infused into the udder had been absorbed after 72 h. Tissue distributions of radioactivity in decreasing order of abundance were: kidney, udder, liver, duodenum, muscular tissue, adipose tissue, and bile.

High-pressure liquid chromatographic separation, identification, and determination of sulfa drugs and their metabolites in urine.

A high-pressure liquid chromatographic method for the separation and quantitative determination of sulfamethazine, sulfathiazole, and their N4-acetylated metabolites on an amino-bonded reversed-phase column was developed. The method is suitable for the analysis of these compounds in pure solutions as well as in cattle urine. Retention times were reproducible. Injection volumes containing 0.2 mug of individual sulfonamides or their acetyl derivatives were successfully quantitated; coefficients of variation ranged from 0 to 0.073 for individual sulfonamides.

High-pressure liquid chromatographic determination of tetracyclines in urine.

The quantitation of oxytetracycline, tetracycline, and chlortetracycline was accomplished by high-pressure liquid chromatography using an anion-exchange column. The tetracyclines were extracted from urine as their calcium complexes. Concentrations as low as 12 microgram of oxytetracycline/ml and 4 microgram of tetracycline and chlortetracycline/ml were quantitated accurately. The relative standard deviation of the method varied from 0 to 5%.

Analysis of xanthophylls in corn by HPLC.

An HPLC method was developed using the C-30 carotenoid column to separate and identify the major xanthophylls in corn (lutein, zeaxanthin, and beta-cryptoxanthin). A photodiode array detector and a mobile phase consisting of methyl tert-butyl ether/methanol/water was used. All three xanthophylls eluted in less than 25 min. Yellow dent corn had a total xanthophyll content of 21.97 microg/g with lutein content of 15.7 microg/g, zeaxanthin content of 5.7 microg/g, and beta-cryptoxanthin of 0.57 microg/g. Commercial corn gluten meal had a 7 times higher concentration of xanthophylls (145 microg/g), and deoiled corn contained 18 microg/g, indicating that the xanthophylls are probably bound to the zein fraction of corn proteins.

Identification of the trans isomers of octadecenoic acid in human milk.

The presence of trans octadecenoic acid isomers was detected and analyzed in 24 hr pooled samples of human milk. Amounts of the trans isomers of the C18 monoenes ranged from 2% to 4% of the total fatty acids. For purposes of comparison, three commonly used brands of infant formula were also analyzed and found to contain 0.1% to 1.3% of trans monoene isomers. Data indicate that breast-fed and bottle-fed infants are receiving minimal levels of trans fatty acids via milk.

Liver lipid alterations in rats fed arginine deficient diets.

Arginine deficiency is associated with a marked increase in liver lipids in the rat. Triglyceride accumulation accounts for most of the fatty infiltration. Cholesterol concentration per gram of liver increased approximately 280% above control rats receiving dietary arginine. The percentage of phospholipids was significantly decreased in the arginine-deficient rat liver compared to controls. The fatty acid composition revealed a significant reduction in the reduction in the percentage of palmitic, palmitoleic, oleic, and linoleic acids. However, both stearic and arachidonic acids were increased approximately 250 and 160%, respectively, in arginine-deficient livers compared to controls. Arginine deficiency in the rat causes a marked alteration in lipid metabolism similar to that observed with orotic acid feeding. The similarities or arginine deficiency and orotic acid feeding are discussed.

The presence of oxidative polymeric materials in encapsulated fish oils.

Encapsulated health food oils such as fish oils are readily available in health food stores, pharmacies, and supermarkets. They are popular in the United States as well as in the European countries. However, such oils, because of their high degree of unsaturation, are easily oxidized and form complex mixtures of high molecular weight oxidation products. The present work reports the application of high-performance size exclusion chromatography to the determination of these materials in encapsulated fish oils. Of the six samples studied, five showed from 1-10% of dimeric triacylglycerols and one contained 6.3% trimeric triacylglycerols and 3.1% oligomeric triacylglycerols. Further investigation of this sample with silicic acid chromatography indicated that it contained a total of 36.3% polar material.

Magnesium silicate treatment of dietary heated fats: effects on rat liver enzyme activity.

In an effort to reduce the deleterious nutritional effects of oxidation products generated in heated fats, a partially hydrogenated soybean oil (PHSBO) used 7 d (7-DH) for frying foodstuffs was obtained from a commercial deep-fat frying operation. The used fat was treated with magnesium silicate (T-7DH). Isocaloric diets containing 15% of either 7-DH or T-7-DH fats were prepared and fed to male weanling rats for 10 wk in a pair-feeding experiment and compared to control rats fed nonheated PHSBO (NH). Animals fed the 7-DH diet showed higher liver enzyme cytochrome b5 and P450 activity than the T-7DH diet compared to the NH group, suggesting a positive effect of the treatment. These results suggested the presence of lower amounts of harmful compounds in the diet containing the heated used oil which had been treated with the active adsorbent.

Effects of dietary heated fats on rat liver enzyme activity.

The objective of this study was to evaluate the effects of dietary heated fats from a commercial deep-fat frying operation on rat liver enzyme activity. The fats, partially hydrogenated soybean oil (PHSBO) used for four days and for 7 days (7-DH) for frying foodstuffs in a commercial restaurant, were fed to rats in either free access to food or by pair-feeding graded doses. All diets were isocaloric and contained 15 g/100 g of diet. Experiments were conducted with control rats fed non-heated (NH) PHSBO diet. Animals fed 7-DH diet in each set of experiments had larger amounts of cytochromes P450 and b5 and greater activity of NADPH-cytochrome P450 reductase when compared to controls. The activities of carnitine palmitoyltransferase-I and isocitrate dehydrogenase were significantly lower in rats fed test diets in comparison to controls. A significantly depressed activity of glucose 6-phosphate dehydrogenase was also noticed for these animals when compared to those fed NH. In addition, liver and microsomal protein concentrations were significantly greater in rats fed the used oils in comparison to controls, and liver glycogen was significantly lower.

Nutrition and metabolic studies of methyl esters of dimeric fatty acids in the rat.

Methyl esters of dimeric fatty acids were prepared by fractionating a mixture of conjugated linoleic and oleic acids that was heated for 24 hr at 300 C in the absence of air. Rats fed diets containing less than 1% dimers showed no significant difference (P less than 0.05) in the growth rate, feed efficiency, liver:body weight ratio, and lipid:liver weight ratio from those fed normal diets. A lymph cannulation study using 14C labeled dimers showed that ca. 0.4% of the dimers fed were absorbed within 12 hr and were transported as free acids in the lymph. Within a 28 hr period, 2% of the labeled dimers fed by gastric intubation were oxidized to 14CO2, and 1% radioactivity was recovered from the urine. The metabolism of methyl oleate appeared normal for rats prefed diets containing dimers.

Nutritional effects of the cyclic monomers of methyl linolenate in the rat.

Low levels (0.0075, 0.0225, and 0.15%) of cyclic fatty acid methyl esters (greater than 98% pure) were incorporated into diets of weanling rats fed different levels of protein. Animals on low protein diets (8-10% casein) exhibited decreased wt gains and feed consumption with increasing levels of cyclic esters in their diets after 6 weeks. Liver enlargements due to a significant (P less than 0.01) accumulation of liver lipid were noted in animals receiving 0.15% cyclic fatty acid esters in their diets.

Cyclic fatty acid monomers from dietary heated fats affect rat liver enzyme activity.

This study was conducted to investigate the effects of dietary cyclic fatty acid monomers (CFAM), contained in heated fat from a commercial deep-fat frying operation, on rat liver enzyme activity. A partially hydrogenated soybean oil (PHSBO) used 7 d (7-DH) for frying foodstuffs, or 0.15% methylated CFAM diets was fed to male weanling rats in comparison to a control group fed a nonheated PHSBO (NH) diet in a 10-wk experiment. All diets were isocaloric with 15% fat. Animals fed either CFAM or 7-DH diets showed increased hepatic content of cytochrome (cyt.) b5 and P450 and increased activity of (E.C. 1.6.2.4) NADPH-cyt. P450 reductase in comparison to the control rats. In addition, the activities of (E.C. 2.3.1.21) carnitine palmitoyltransferase-I and (E.C. 1.1.1.42) isocitrate dehydrogenase were significantly decreased when compared to that of rats fed the NH diet. A significantly depressed activity of (E.C. 1.1.1.49) glucose 6-phosphate dehydrogenase was also observed for these animals compared to the control rats fed NH diet. Moreover, liver and microsomal proteins were significantly increased when CFAM or 7-DH diets were fed to animals in comparison to controls while liver glycogen was decreased significantly in experimental groups of rats. The results obtained in this study indicate that the CFAM in the diet from either synthetic sources or used fats increase the activity of liver enzyme systems that detoxify them.

The effects of cyclic fatty acid monomers on cultured porcine endothelial cells.

The popularity of polyunsaturated oils used in food applications and preparation continues to appreciate as a result of positive health claims. With polyunsaturated oils inherently more susceptible to oxidative and thermal degradation, the formation of new fatty acid species increases considerably. The presence of one species known as cyclic fatty acid monomers (CFAM) has been detected as a component of many oils subjected to various thermal processes including deep-fat frying. The effect of CFAM on metabolic processes has not been fully characterized. In this study, confluent porcine aortic endothelial cells incorporated CFAM into their polar and nonpolar lipid fractions following a 48-h exposure to 31 and 62 ppm CFAM in the culture medium. Subsequently, the influence of CFAM incorporation on various membrane-dependent physical properties and biochemical processes was investigated. CFAM decreased the lipid packing order of the membrane bilayer core but did not alter the lipid packing order of lipid chain segments at or near the lipid-water interface of the membrane. CFAM led to significant reductions in Ca2+ ATPase activity and monolayer integrity while eliciting a significant increase of prostacyclin synthesis and secretion.

Fatty acid patterns in iron-deficient maternal and neonatal rats.

To determine the effects of maternal iron deficiency on lipid composition and fatty acid patterns in offspring, rats were fed ad libitum diets containing 5 ppm iron (deficient) (n=8) or 320 ppm iron (control) (n=7) and deionized water from day-1 of gestation through day-18 of lactation. On day-2 of lactation, litters were standardized to three male and three female pups. On day-18, pups were fasted for 4 hr before tissue and blood collection. Significant changes in serum and liver lipid concentrations and fatty acid patterns were observed in deficient pups. Serum triglycerides, cholesterol and phospholipids and liver triglycerides, cholesterol, and cholesteryl esters were increased. In deficient pups, percentage total fatty acids of 14:0, 16:1, 18:1, 18:2 from serum lipids were increased; in liver, 14:0, 18:2, 18:3 were increased; 18:0 and 20:4 were decreased in both serum and liver. Dam serum lipid levels did not differ between groups. Lipid changes observed in iron-deficient pups did not consistently reflect the milk, serum or liver lipid patterns observed in dams. Altered lipid composition and fatty acid patterns of iron-deficient pups thus appear to be of endogenous origin.

High-performance liquid chromatography of human milk triacylglycerols and gas chromatography of component fatty acids.

Human milk triacylglycerols were separated by high-performance liquid chromatography. A 5-mu Supelcosil LC-18 column (Supelco, Inc., Bellefonte, PA) was used with acetone/acetonitrile (64:36, vol/vol) as mobile phase. Triacylglycerols were tentatively identified based on theoretical carbon number and relative retention time. Despite changes resulting from dietary fat variation, the major component triacylglycerols were those composed of palmitic, oleic and linoleic acids. Triacylglycerols with palmitic, stearic and oleic acids were present as minor components. Fatty acids were quantified by gas chromatography relative to an internal standard. Ratios of n-6/n-3 fatty acids were found to be higher than previously reported.

High performance reversed phase chromatography of cholesterol and cholesteryl esters of human plasma lipoproteins.

Cholesterol and cholesteryl esters were separated according to their carbon number and number of double bonds by high performance reversed-phase chromatography (HPRC) using acetonitrile/chloroform/methanol (1:1:1, v/v) as a mobile phase. It was found that within the same equivalent carbon number (ECN) category, cholesteryl esters with the highest number of double bonds eluted ahead of those with a lower number of double bonds, and with the cis isomers eluting ahead of their trans partners. Thus, cholesteryl oleate (C27-18:1c) elutes ahead of cholesteryl palmitate (C27-16:0) and ahead of cholesteryl elaidate (C27-18:1t). Human lipoprotein, as well as rat liver cholesteryl esters, were separated using this technique.

Rapid determination of double bond configuration and position along the hydrocarbon chain in cyclic fatty acid monomers.

This study reports the structural elucidation of diunsaturated 5- or 6-membered ring cyclic fatty acid monomers (CFAM) isolated from heated flaxseed oil by complementary gas chromatography (GC)-mass spectrometry (MS) and GC-matrix isolation-Fourier transform infrared spectroscopy (MI-FTIR). Infrared measurements of CFAM were carried out on methyl ester derivatives as well-resolved chromatograms were obtained on a polar 100% cyanopropyl polysiloxane capillary GC column. By contrast, electron ionization MS of methyl ester derivatives was of limited value because of double bond migration during the ionization process in the mass spectrometer. This communication reports definitive MS fragmentation patterns that can confirm ring position and double bond position along the fatty acid chain in 1,2-disubstituted CFAM determined as 2-alkenyl-4,4-dimethyl-oxazoline derivatives. Double bond configuration (cis, trans, or conjugated cis,cis) in CFAM was confirmed by GC-MI-FTIR. The presence of CFAM, degradation products found in used frying oils, is a potential source of dietary toxicity.