Concentrations Of Long-chain Fatty Acids Research Articles

Is Metabolic Syndrome X a Disorder of the Brain?

Abdominal obesity, atheroslcerosis, insulin resistance, hyperlipidemias, hypertension, and type 2 diabetes mellitus are important components of metabolic syndrome X. An increase in pro-inflammatory cytokines, decrease in the concentrations of endothelial nitric oxide (eNO) and adiponectin, and an alteration in hypothalamic peptides that control satiety, hunger, and food intake have been reported in metabolic syndrome X. Although when and how metabolic syndrome X is initiated is not clear, there is evidence to suggest that increased consumption of high-energy diet, saturated and trans-fats by pregnant women and lactating mothers could trigger changes in the concentrations of long-chain polyunsaturated fatty acids (LCPUFAs) in maternal and fetal plasma and tissues. LCPUFAs have a modulatory influence on neuronal growth, maturation and synapse formation; influence the actions of hypothalamic peptides, neuropeptides, leptin, adiponectin, and various cytokines, especially during the perinatal period. In addition, LCPUFAs function as endogenous inhibitors of HMG-CoA reductase and ACE (angiotensin converting enzyme), augment eNO synthesis, modulate vascular tone, and potentiate insulin action both in the peripheral tissues and brain. Hence, sub-optimal maternal and fetal plasma and tissue concentrations of LCPUFAs increase pro-inflammatory cytokine levels that could trigger the development of metabolic syndrome X in those children who have a genetic predisposition, and continue to take highenergy diet, and saturated and trans-fats. This implies that perinatal interventions in the form of adequate supplementation of LCPUFAs could be of significant benefit in the prevention of metabolic syndrome X. Preliminary evidence suggests that supplementation of LCPUFAs can restore the levels of hypothalamic peptides to normal. In addition, weight loss due to Roux-en-gastric bypass procedure done in diet-induced obese animals decreased inflammation, restored hypothalamic “body weight/ appetite/ satiety set point” by restoring hypothalamic neuropeptides to normal, suggesting a cross talk between gastrointestinal hormones and hypothalamus. These evidences suggest that metabolic syndrome X occurs in a genetically predisposed subject as a result of interaction(s) between hypothalamic peptides, gastrointestinal tract, cytokines, nutrition, and life style factors. Keywords: Metabolic syndrome X, cytokines, leptin, nutrition, exercise, hypothalamus, serotonin, dopamine, neuropeptide Y, melanocyte stimulating hormone

Acute Rise of Omega-3 Polyunsaturated Fatty Acids During Hemodialysis Treatment

Hemodialysis patients have an extremely high rate of cardiac arrhythmia-induced sudden cardiac death, although the risk during the hemodialysis procedure is relatively low. A higher blood content of long-chain omega-3 polyunsaturated fatty acids (PUFAs) is believed to reduce the risk of sudden cardiac death. We performed this study to measure the effect of a single-standard hemodialysis treatment on plasma and erythrocyte omega-3 PUFA levels in chronic hemodialysis patients. This was a prospective, observational study. The study was performed in one outpatient hemodialysis unit. Study subjects were all chronic, stable hemodialysis patients. There were no interventions. Plasma and erythrocyte fatty-acid levels were measured before and immediately after a hemodialysis session. Plasma levels of long-chain PUFAs, including the omega-3 fatty acids of interest, all rose, whereas those of shorter-chain or more saturated fatty acids either remained unchanged or fell. A similar trend was seen in erythrocytes, though the results did not reach statistical significance. The hemodialysis procedure induces acute increases of long-chain omega-3 PUFAs in the blood. This effect may help explain why malignant cardiac arrhythmias occur relatively infrequently during hemodialysis.

Adrenomyeloneuropathie als Ursache eines Morbus Addison

A 25-year old male, with a 3-year history of spastic paraparesis and a disturbance of bladder emptying, developed Addison's disease (plasma ACTH 1250 pg/ml, depressed cortisol values with loss of diurnal rhythm, potassium 6.8 mmol/l, sodium 123 mmol/l) associated with a urinary tract infection. The suspected diagnosis of adrenomyeloneuropathy was confirmed by the finding of raised plasma long-chain fatty acid concentrations. The patient was immediately given 0.4 mg fludrocortisone as a bolus, followed by 0.1 mg daily maintenance therapy, the urinary tract infection having already been successfully treated. Substitution therapy with hydrocortisone was also initiated (starting dose 30-20-10 mg daily, maintainance dose 20-10-5 mg daily). As a result, the electrolyte concentrations returned to normal and the neurological features improved. A family study was undertaken to determine whether the adrenomyeloneuropathy was an X-linked recessive form. Both the symptom-free mother (carrier) and the 19-year-old brother, who had suffered from Addison's disease since the third year of life, had raised plasma long-chain fatty acid concentrations. Both brothers were started on a diet low in long-chain fatty acids. Estimation of long-chain fatty acids is indicated in boys or young adult males with peripheral neuropathy or Addison's disease of uncertain aetiology.

The Feeding Value of Corn Distillers Solubles for Lactating Dairy Cows

Fifteen Holstein cows (10 multiparous and 5 primiparous) in early to mid lactation (79.3±9.2 d in milk) were used in a multiple 5×5 Latin square design with 4-wk periods to evaluate and compare the use of condensed corn distillers solubles (CCDS) and dried distillers grains with solubles (DDGS) in the total mixed ration. The forage portion of the diets was kept constant at 27.5% corn silage and 27.5% alfalfa hay (dry matter basis). Diets were 1) 0% distillers grains products (control); 2) 18.5% DDGS; 3) 10% CCDS; 4) 20% CCDS; and 5) a combination diet of 18.5% DDGS with 10% CCDS. Diets 2 and 3 contained 2% fat from DDGS or CCDS, whereas diet 4 contained 4% fat from CCDS and diet 5 contained 4% fat from the blend of DDGS and CCDS. The diets were balanced to provide 17% crude protein with variation in acid detergent fiber, neutral detergent fiber, and fat concentration. Dry matter intake (21.5 kg/d) was similar for all diets. Milk yield (33.8, 36.2, 35.5, 36.0, and 36.0 kg/d) tended to be greater for diets 2 to 5 than for diet 1, whereas yields of fat (1.04 kg/d), protein (1.02 kg/d), fat percentage (2.94), and protein percentage (2.98) were similar for all diets. Energy-corrected milk (32.2 kg/d) and feed efficiency (1.58kg of energy-corrected milk/kg of dry matter intake) were similar for all diets. Milk urea nitrogen (15.0, 10.9, 11.1, 11.0, and 11.4mg/dL) as well as blood urea nitrogen (15.6, 12.5, 14.6, 13.8, and 14.2mg/dL) were decreased in diets 2 to 5 compared with diet 1. Milk concentrations of long-chain fatty acids as well as polyunsaturated fatty acids were greater and medium-chain fatty acid concentrations were lower for diets 2 to 5 compared with diet 1. Concentrations of cis-9, trans-11 conjugated linoleic acid (CLA; 0.33, 0.68, 0.51, 0.85, and 1.07 g/100g of fatty acids) as well as trans-10, cis-12 CLA (<0.01, 0.01, <0.01, 0.02, and 0.02 g/100g of fatty acids) were greater for diets 2 to 5 compared with diet 1. Molar proportions of ruminal acetate decreased and propionate increased for diets 2 to 5 compared with diet 1. The results showed that CCDS is as effective as DDGS in replacing soybean meal and corn grain in the total mixed ration.

Alcohol induced effects on kidney

After administration ethanol and its metabolites go through kidneys and are excreted into urine, and its content in the urine is higher than that of the blood and the liver. Chronic ethanol administration decreases the renal tubular reabsorption and reduces renal function. Multiple functional abnormalities of renal tubules may be associated with ethanol-induced changes in membrane composition and lipid peroxidation. The vulnerability of the kidney to oxidative damage has been partly attributed to its high content of long-chain polyunsaturated fatty acids. Renal ultra structural abnormalities due to ethanol exposure may be important in the genesis of functional disturbances. Increased oxidative stress and endothelial dysfunction with their complex interrelationships are relevant aspects of atherogenesis in chronic renal failure. Antioxidants, particularly polyphenols are expected to decrease the vulnerability of the kidney to oxidative challenges.

Phospholipid and triacylglycerol fatty acid content and pattern in the cardiac endothelium of rats depleted in long‐chain polyunsaturated ω3 fatty acids

Rats depleted in long-chain polyunsaturated omega3 fatty acids (omega3-depleted rats) display several features of the metabolic syndrome including hypertension and cardiac hypertrophy. This coincides with alteration of the cardiac muscle phospholipid and triacylglycerol fatty acid content and/or pattern. In the present study, the latter variables were measured in the cardiac endothelium of normal and omega3-depleted rats. Samples derived from four rats each were obtained from 16 female normal fed rats and three groups of 36-40 female fed omega3-depleted rats each aged 8-9, 15-16 and 22-23 weeks. At comparable mean age, the ratio between the square root of the total fatty acid content of phospholipids and cubic root of the total fatty acid content of triacylglycerols was lower in omega3-depleted rats than in control animals. The total fatty acid content of triacylglycerols was inversely related to their relative content in C20:4omega6. Other differences between omega3-depleted rats and control animals consisted in a lower content of long-chain polyunsaturated omega3 fatty acids in both phospholipids and triacylglycerols, higher content of long-chain polyunsaturated omega6 fatty acids in phospholipids, higher activity of delta9-desaturase (C16:0/C16:1omega7 and C18:0/C18:1omega9 ratios) and elongase [(C16:0 + C16:1omega7)/(C18:0 + C18:1omega9) and C20:4omega6/C22:4omega6 ratios], but impaired generation of C22:6omega3 from C22:5omega3 in the former rats. These findings support the view that cardiovascular perturbations previously documented in the omega3-depleted rats may involve impaired heart endothelial function.

Methylmalonic acidaemia: Examination of genotype and biochemical data in 32 patients belonging to mut, cblA or cblB complementation group

Methylmalonic acidaemia (MMA) is a genetic disorder caused by defects in methylmalonyl-CoA mutase or in any of the different proteins involved in the synthesis of adenosylcobalamin. The aim of this work was to examine the biochemical and clinical phenotype of 32 MMA patients according to their genotype, and to study the mutant mRNA stability by real-time PCR analysis. Using cellular and biochemical methods, we classified our patient cohort as having the MMA forms mut (n = 19), cblA (n = 9) and cblB (n = 4). All the mut (0) and some of the cblB patients had the most severe clinical and biochemical manifestations, displaying non-inducible propionate incorporation in the presence of hydroxocobalamin (OHCbl) in vitro and high plasma odd-numbered long-chain fatty acid (OLCFA) concentrations under dietary therapy. In contrast, mut (-) and cblA patients exhibited a milder phenotype with propionate incorporation enhanced by OHCbl and normal OLCFA levels under dietary therapy. No missense mutations identified in the MUT gene, including mut (0) and mut (-) changes, affected mRNA stability. A new sequence variation (c.562G>C) in the MMAA gene was identified. Most of the cblA patients carried premature termination codons (PTC) in both alleles. Interestingly, the transcripts containing the PTC mutations were insensitive to nonsense-mediated decay (NMD).

Oxidized Fat Reduces Milk Triacylglycerol Concentrations by Inhibiting Gene Expression of Lipoprotein Lipase and Fatty Acid Transporters in the Mammary Gland of Rats

Feeding oxidized fats to lactating rats causes a strong reduction of triacylglycerol concentration in the milk. The reason for this, however, has not yet been elucidated. Pregnant Sprague-Dawley rats were assigned to 2 groups of 11 rats each and fed diets containing either fresh fat (FF group) or an oxidized fat (OF group) from d 1 to d 20 of lactation. Concentrations of triacylglycerols and long-chain fatty acids in the milk and weight gain of suckling pups were lower in the OF group than in the FF group (P < 0.05). Concentrations of medium-chain fatty acids in the milk and messenger RNA (mRNA) abundance of lipogenic enzymes in the mammary gland did not differ between the 2 groups of rats. However, the OF group had a lower concentration of triacylglycerols and nonesterified fatty acids (NEFA) in plasma and lower mRNA concentrations of lipoprotein lipase and fatty acid transporters in the mammary gland than the FF group (P < 0.05). Moreover, the OF group had higher mRNA concentrations of hepatic lipase, fatty acid transporters, and several genes involved in fatty acid oxidation in the liver than the FF group (P < 0.05). The present findings suggest that a dietary oxidized fat lowers the concentration of triacylglycerols in the milk by a reduced uptake of fatty acids from triacylglycerol rich-lipoproteins and NEFA into the mammary gland. The study, moreover, indicates that an oxidized fat impairs normal metabolic adaptations during lactation, which promote the utilization of metabolic substrates by the mammary gland for the synthesis of milk.

The Effect of Cocoa and Polydextrose on Bacterial Fermentation in Gastrointestinal Tract Simulations

Effects of cocoa mass and supplemented dietary fiber (polydextrose) on microbial fermentation were studied by combining digestion simulations of stomach and small intestine with multi-staged colon simulations. During the four phases of digestion, concentrations of available soluble proteins and reducing sugars reflected in vivo absorption of nutrients in small intestine. In colon simulation vessels, addition of polydextrose to digested cocoa mass significantly increased concentrations of total short-chain fatty acids and butyric acid, from 103 to 468 mM (P<0.01) and from 12 to 22 mM (P<0.01), respectively. Long-chain fatty acid concentrations (decreasing from 1,222 to 240 mM) were mainly affected by the presence of digested cocoa mass. Cocoa mass with or without polydextrose addition significantly decreased production of cadaverine (P<0.02) and branched-chain fatty acids compared to control during colon simulations. Results indicate beneficial effects on metabolism of colonic microbiota after digestion of cocoa mass, and even more so with polydextrose addition.

Analysis of long-chain ω-3 fatty acid content in fish-oil supplements

Omega-3 polyunsaturated fatty acids (long-chain omega-3 PUFA) have proved to be beneficial in atherosclerosis, arrhythmia and hypertriglyceridemia in several studies, which has led national and international societies to recommend an intake of 1 g/d long-chain omega-3 PUFA for anti-atherosclerotic and antiarrhythmic purposes or 2-4 g/d for a lipid lowering effect. Numerous preparations are marketed for supplementing western diet, which is low in long-chain omega-3 PUFA. Since these preparations vary in their long-chain omega-3 PUFA content, we tested nine commercially available products for their fatty acid composition. Nine commercially available omega-3 fatty acid supplements were analyzed using capillary gas chromatography to determine their fatty acid content. The nine preparations showed huge differences, up to 63.7 +/- 1.58 mol% (P = 0.002), in their longchain omega-3 fatty acid content. Most of them failed to achieve the daily recommended dose of 1 g, even when administered at the highest dosage according to the manufacturer's recommendations. Eight of the preparations contained either equal or significantly greater amounts of long-chain omega-3 PUFA than denoted by the manufacturer; one preparation did not provide any information. The highest percentage of DHA and EPA was detected in Omacor(95.80 +/- 0.63%) and Percucor (76.8 +/- 7.109%). Administering long-chain omega-3 fatty acid preparations may result in huge differences in terms of the actual amount ingested. It is therefore advisable to use the most standardized and purified products available.

Rapid determination of C12–C26 non‐derivatized fatty acids in human serum by fast gas chromatography

The concentration of long-chain fatty acids (LCFAs) in human serum is closely related to human health. It is therefore important to develop a fast, low-cost, efficient method for their determination. In this study, by using fast temperature programming and micro-bore short capillary columns, a fast gas chromatography method was developed for the direct analysis of non-derivatized LCFAs including n-dodecanoic acid to n-hexacosanic acid (C12:0-C26:0, even numbers only), linoleic acid (C18:2), oleic acid (C18:1), and erucic acid (C22:1) within 4.0 min. Method optimization including extraction and separation conditions is considered, and the analysis of real serum samples is presented. The results show that ten LCFAs were well separated with sufficient resolution, and the detection limit was in the range of 2.8-9.6 microg/mL. The reproducibility (RSD) for both intra-day and inter-day determination was always less than 15%, and the recoveries for these LCFAs were from 63.1 to 97.0%.

Production Performance and Milk Composition of Dairy Cows Fed Whole or Ground Flaxseed With or Without Monensin

Eight multiparous Holstein cows averaging 570±43kg of body weight and 60±20 d in milk were used in a double Latin square design with four 21-d experimental periods to determine the effects of feeding ground or whole flaxseed with or without monensin supplementation (0.02% on a dry matter basis) on milk production and composition, feed intake, digestion, blood composition, and fatty acid profile of milk. Intake of dry matter was similar among treatments. Cows fed whole flaxseed had higher digestibility of acid detergent fiber but lower digestibilities of crude protein and ether extract than those fed ground flaxseed; monensin had no effect on digestibility. Milk production tended to be greater for cows fed ground flaxseed (22.8kg/d) compared with those fed whole flaxseed (21.4kg/d). Processing of flaxseed had no effect on 4% fat-corrected milk yield and milk protein and lactose concentrations. Monensin supplementation had no effect on milk production but decreased 4% fat-corrected milk yield as a result of a decrease in milk fat concentration. Feeding ground compared with whole flaxseed decreased concentrations of 16:0, 17:0, and cis6-20:4 and increased those of cis6-18:2, cis9, trans11-18:2, and cis3-18:3 in milk fat. As a result, there was a decrease in concentrations of medium-chain and saturated fatty acids and a trend for higher concentrations of long-chain fatty acids in milk fat when feeding ground compared with whole flaxseed. Monensin supplementation increased concentrations of cis9 and trans11-18:2 and decreased concentrations of saturated fatty acids in milk fat. There was an interaction between flaxseed processing and monensin supplementation, with higher milk fat concentration of trans11-18:1 for cows fed ground flaxseed with monensin than for those fed the other diets. Flaxseed processing and monensin supplementation successfully modified the fatty acid composition of milk fat that might favor nutritional value for consumers.

Therapeutic Challenge to Adiposity of the Heart

See related article, pages 1208–1217 The recent increase in the prevalence of obesity is one possible explanation for the adverse trends in cardiovascular morbidity and mortality. Hospitalizations for congestive heart failure have increased, and the decline in death because of coronary heart disease has leveled off. In parallel with these aspects, there is emerging evidence that inherited and acquired cardiomyopathies are associated with marked intracellular lipid accumulation in the heart.1–5 Three types of mismatches between uptake and utilization of long chain fatty acid (LCFA) lead to abnormally high intracellular LCFA concentrations in the heart, resulting in lipotoxic cardiomyopathy. First, inborn errors in myocardial β-oxidation are associated with heart failure, arrhythmias, sudden death, and pathologic lipid accumulation with a 3-fold increase in phospholipids and 100-fold increase in triglycerides in the myocardium.1 Second, myocardial metabolism switches from utilization of LCFA to utilization of glucose during the development of cardiac hypertrophy and in the ischemic and failing heart. Although this metabolic switch initially serves an adaptive function, accumulation of intracellular LCFA in these acquired conditions contributes to contractile dysfunction and the generation of cardiac arrhythmias.2 Third, several-fold increased cardiac myocyte triglyceride stores are observed in animal models of obesity and diabetes, in which high serum free fatty acid levels promote LCFA uptake in excess of tissue capacity for utilization.3,4 This lipid accumulation contributes to cardiac myocyte apoptosis by nonoxidative metabolic pathways, such as ceramide synthesis, and to congestive heart failure (Figure). Even in humans, myocardial lipid content has been recently reported to increase with the degree of adiposity and contribute to the adverse structural and functional cardiac adaptations, suggesting that myocardial lipid content is a biomarker and putative therapeutic target for cardiac disease in obese patients.5 Indeed, one trial of the medium-chain triglyceride-enriched diet rescued the baseline …

Stearic acid is well absorbed from short- and long-acyl-chain triacylglycerol in an acute test meal

Absorption of stearic acid from natural oils has been shown to be efficient, but it is claimed to be lower from short- and long-acyl-chain triacylyglycerol molecules (Salatrim). The aim was to measure the apparent absorption of stearic acid from Salatrim fat in an acute test meal. Double-blind crossover study. Ten healthy male volunteers, of whom eight completed the study. The subjects were studied on two occasions after consumption of a single high-fat meal either without (control) or with 30 g of Salatrim. Fecal samples were collected for 96 h after the meal and the fat was extracted for analysis of the content and composition of free and esterified long-chain fatty acids. Baseline fecal fat was 5.6+/-2.6 g/day increasing to 10.4+/-4.9 g/day after addition of Salatrim (P=0.001). During the whole collection period, the baseline fecal free and esterified fatty acids were 2.6+/-2.3 and 0.8+/-0.7 g, respectively. After Salatrim meal the corresponding figures increased to 5.9+/-3.6 g (P=0.001) and 1.5 (+/-1.2) g (P=0.003), respectively. The total fecal stearic acid after control meal was 0.97+/-0.9 g. Consumption of Salatrim with 16.7+/-0.5 g of stearic acid increased the content to 3.12+/-1.6 g (P<0.001), with apparent absorption of 87%. The apparent absorption of stearic acid does not differ from its absorption from natural fats. The status of Salatrim as a low-energy fat substitute needs to be re-evaluated. University of Turku.

Good fat/bad fat

Good fat/bad fat

Preclinical investigations of a medium-chain triglyceride:fish oil emulsion III. Experiments in cultured endothelial cells

The bolus intravenous injection of a novel medium-chain triglyceride:fish oil emulsion was recently reported to provoke a rapid and sustained increase in the cell phospholipid content of long-chain polyunsaturated omega3 fatty acids in both rats and human subjects. This report deals mainly with a comparison between this and other emulsions, as well as albumin-bound omega3 fatty acids, in terms of the time course, reversibility and concentration dependency for the incorporation of the omega3 fatty acids in the phospholipids of cultured endothelial cells. The results document that the new emulsion is quite efficient for a rapid and sustained enrichment of phospholipids in long-chain polyunsaturated omega3 fatty acids. The potential beneficial effects of such an enrichment in terms of aortic endothelial and cardiac function are emphasized.

Malonyl CoA control of fatty acid oxidation in the newborn heart in response to increased fatty acid supply

The concentration of fatty acids in the blood or perfusate is a major determinant of the extent of myocardial fatty acid oxidation. Increasing fatty acid supply in adult rat increases myocardial fatty acid oxidation. Plasma levels of fatty acids increase post-surgery in infants undergoing cardiac bypass operation to correct congenital heart defects. How a newborn heart responds to increased fatty acid supply remains to be determined. In this study, we examined whether the tissue levels of malonyl CoA decrease to relieve the inhibition on carnitine palmitoyltransferase (CPT) I when the myocardium is exposed to higher concentrations of long-chain fatty acids in newborn rabbit heart. We then tested the contribution of the enzymes that regulate tissue levels of malonyl CoA, acetyl CoA carboxylase (ACC), and malonyl CoA decarboxylase (MCD). Our results showed that increasing fatty acid supply from 0.4 mmol/L (physiological) to 1.2 mmol/L (pathological) resulted in an increase in cardiac fatty acid oxidation rates and this was accompanied by a decrease in tissue malonyl CoA levels. The decrease in malonyl CoA was not related to any alterations in total and phosphorylated acetyl CoA carboxylase protein or the activities of acetyl CoA carboxylase and malonyl CoA decarboxylase. Our results suggest that the regulatory role of malonyl CoA remained when the hearts were exposed to high levels of fatty acids.

Insulated, uninsulated and outdoor housing for replacement beef heifers on restricted grass silage-based diet in a cold environment

Abstract The present experiment studied whether replacement beef heifers, offered restricted amounts of a grass silage-based diet, can be overwintered in outdoor housing facilities in cold Nordic conditions (minimum temperature approximately − 35 °C). Twenty-one Hereford heifers, initial live weight (LW) 237 kg in Experiment 1 and 256 kg in Experiment 2, were selected for a two-year study. In both experiments, the treatments consisted of three winter housings which were Insulated pen (I), Uninsulated pen (U) and Outdoor area with a rain shelter (O). Grass silage supplemented with oats was offered restricted and the heifers received daily during winter on average 63 and 65 MJ metabolizable energy in Experiment 1 and 2, respectively. The live weight gain of the heifers in treatment U (795 g/d) was higher than in the other treatments (I; 760 and O; 747 g/d). No significant differences in the body condition score (scale from extremely thin, 0 to extremely fat, 5) were observed between the treatments. In Experiment 1, the serum concentrations of long-chain fatty acids were lower in the heifers in treatment I than in the heifers in the other treatments, probably due to increased lipolysis of the heifers in treatment I. In both experiments the serum concentrations of urea were lower and concentrations of total proteins higher in the animals in treatment I than in the other animals. No clear harmful effects, like muscle injuries, extraordinary stress or increased occurrence of diseases, could be observed in any of the treatments. The breeding season was 78 and 83 days in Experiment 1 and 2, respectively. The conception rate after natural breeding was 95% in both experiments. On the basis of the results, replacement beef heifers on a restricted feeding scheme can be overwintered outdoors in Nordic conditions without negative effects on animal performance. Nevertheless, the outdoor winter housing facilities must protect the animals from becoming wet and dirty and thus should be equipped with a rain shelter to provide a dry resting area with sufficient bedding material available.

Preclinical investigations of a medium-chain triglyceride:fish oil emulsion. I. Effects of bovine milk lipoprotein lipase on lipid composition

The bolus intravenous injection of a novel medium-chain triglyceride:fish oil emulsion (MCT:FO, 8:2, w:w) was recently found to increase within 60 min the leucocyte and platelet phospholipid content of long-chain polyunsaturated omega3 fatty acids. The present report deals with the effects of bovine milk lipoprotein lipase on the lipid composition of this emulsion. The results are compared to those obtained with either a pure fish oil emulsion or a medium-chain triglyceride: long-chain triglyceride:fish oil emulsion (MLF, 5:4:1). Emphasis is placed on i) differences in the fate of distinct fatty acids initially present in the triglycerides, di glycerides and phospholipids, ii) the generation of unesterified fatty acids relative to their initial content in each emulsion, and iii) the time course for these various events. The comparison between the three emulsions under consideration also provides information relevant to their respective sensitivity to lipoprotein lipase and suitability in terms of the generation of distinct unesterified fatty acids, including long-chain polyunsaturated omega3 fatty acids. Furthermore, attention is drawn to the greater efficiency for the hydrolysis of fatty acids from diglycerides as compared to triglycerides and a transient increase in the paired C8:0/C10:0 ratio in the diglycerides generated from the MCT:FO or MLF emulsion. The present study thus affords novel information relevant to the possible use of the MCT:FO emulsion in human subjects.

Potential Impact of Steatosis on Cytochrome P450 Enzymes of Human Hepatocytes Isolated from Fatty Liver Grafts

Liver grafts discarded for transplantation because of macrosteatosis can constitute a valuable source of human hepatocytes for in vitro metabolic and pharmacotoxicological studies or for therapeutic applications. A condition for using hepatocyte suspensions for these purposes is the preservation of their metabolic competence and, particularly, drug-metabolizing enzymes. A reduction in microsomal cytochrome P450 (P450) activities was observed in fatty livers (>40% steatosis) with respect to normal tissue. Similarly, decreased levels of 7-ethoxycoumarin O-deethylation and testosterone metabolism were observed in human hepatocyte cultures prepared from steatotic liver tissue. To clarify the potential impact of lipid accumulation on human hepatic P450 enzymes, we have used an in vitro model of "cellular steatosis" by incubation of cultured hepatocytes with increasing concentrations (0.25-3 mM) of long-chain free fatty acids (FFA). A dose-dependent accumulation of lipids in the cytosol is induced by FFA mixture. Hepatocytes exposed to 1 mM FFA for 14 h showed lower activity values of CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2D6, CYP2E1, and CYP3A4 enzymes than nontreated hepatocytes (about 45-65% reduction). This treatment also produced significant decreases in CYP1A2, CYP2A6, CYP2C9, CYP2D6, CYP2E1, and CYP3A4 mRNA to about 55 to 75% of mRNA levels in control cells. Our results suggest that although human hepatocytes isolated from steatotic liver show reduced P450 activities, they are metabolically competent and can be used for drug metabolism studies.