Impaired fatty acid oxidation in children on valproic acid and the effect of L-carnitine

Fatty acid oxidation was studied in 12 patients (aged 3 to 19 years) receiving valproic acid (VPA), predominantly as monotherapy, before and after 1 month of L-carnitine supplementation (50 mg/kg/day po) in order to determine whether L-carnitine plays a role in preventing the hepatotoxic effects of this drug. Five of these patients were also studied prior to VPA treatment. Only one patient taking VPA had an abnormally low plasma free carnitine. Acyl-/free carnitine ratios were elevated in five patients on VPA and normalized after L-carnitine supplementation. Mean plasma concentrations of free fatty acids, beta-OH-butyrate, and cumulative excretion of 13CO2 after administration of 1-13C-octanoic acid were not changed by VPA or L-carnitine treatment. Urinary dicarboxylic acids, acylglycines, and octanoylcarnitine were elevated during VPA therapy and unaltered by L-carnitine. These results suggest that, in patients at low risk for VPA-induced hepatotoxicity (patients aged > 2 years and taking VPA as monotherapy), VPA causes metabolic abnormalities resembling those found in inborn errors of mitochondrial beta-oxidation which are not corrected by L-carnitine.     

Purification and properties of fatty acid synthetase from a human breast cell line

A human mammary epithelial cell line (SKBr3) has been identified in which fatty acid synthetase constitutes up to 28%, by weight of the cytosolic proteins. The enzymes has been purified to near homogeneity from this cell line and some of its properties studied. In common with fatty acid synthetases from other animal tissues, the enzyme is a 480 000 dalton dimer of similar molecular weight subunits, it synthesizes predominantly palmitic acid and is inactive in the absence of free coenzyme A. The kinetic properties and amino acid composition of the enzyme are also similar to those of fatty acid synthetases from various tissues of other animals. Appreciable structural resemblance between human and rodent fatty acid synthetases is indicated by studies on the immunological cross-reactivities of these enzymes.     

Total fatty acid composition of duck fatty tissues

Total lipids extracted from duck fatty tissues were fractionated on thin layer plates into polar lipids and neutral lipids. Neutral lipids were similarly fractionated into their components. Fatty acid methyl esters from total lipids were fractionated by gas-liquid-chromatography. Results indicated that duck fatty tissues are mostly formed by neutral lipids and that triglycerides comprise the vast majority of neutral lipids. Results also indicated that the major fatty acids in duck lipids are: oleic greater than linoleic greater than stearic greater than palmitoleic. About 73% of all fatty acids present belong to the C-18 series. The unsaturation level for duck lipids is about 73%.     

Synergist effect of sucrose fatty acid esters on nisin inhibition of gram-positive bacteria

Nisin in combination with the sucrose fatty acid esters, sucrose palmitate (P-1570 and P-1670) or sucrose stearate (S-1570 and S-1670) was tested against a range of Gram-negative and Gram-positive bacteria. Initial liquid culture investigation showed that the sugar ester P-1670 resulted in a synergist enhancement of the bacteriostatic activity of nisin against Gram-positive bacteria and not Gram-negative bacteria. Some enhancement of the bactericidal activity of nisin against Listeria monocytogenes was also observed. This increased nisin inhibitory effect was confirmed on solid media using plates with gradients of pH and NaCl. Synergism was observed with all four sucrose fatty acid esters, which enhanced the antimicrobial activity of nisin against several strains of L. monocytogenes, Bacillus cereus (both cells and spores), Lactobacillus plantarum and Staphylococcus aureus. The combination of nisin and the sucrose fatty acid esters showed no inhibition of Gram-negative bacteria (Salmonella enteritidis, Salm. typhimurium and Pseudomonas aeruginosa).     

Physical and chemical properties of DMP 504, a polyalkylammonium-based bile acid sequestrant

In an open, controlled, multi-centre clinical field trial, seven 'naturally occurring' outbreaks of acute febrile (rectal temperature > or = 39.5 degrees C) respiratory disease in housed calves were treated with a single antimicrobial agent, and either the non-steroidal anti-inflammatory drug (NSAID) carprofen (n = 95) or flunixin meglumine (n = 92) on an alternate basis. Carprofen was administered as a single subcutaneous injection at a mean dosage of 1.4 mg kg-1 (range 1.2 to 1.9 mg kg-1) body weight on the first day and flunixin meglumine by intravenous injection at a mean dosage of 2.0 mg kg-1 (range 1.2 to 2.6 mg kg-1) body weight on the first 3 consecutive days. All calves were examined clinically immediately prior to initial treatment and on three occasions up to 1 week after the end of treatment. There were no statically significant differences between NSAID groups in reduction of clinical parameters between examinations, or in overall efficacy. This trial demonstrated that a single dose of carprofen was equally effective as three daily doses of flunixin meglumine as adjunctive therapy to antimicrobial treatment in acute respiratory disease in calves.     

The effect of under- and overnutrition on essential fatty acid metabolism in childhood

Intermittent catheterisation is suitable for a range of patients and has a high level of patient satisfaction. Careful education is required to minimise the risk of complications and nurses should be aware of the various types of catheter available.     

Relationship between fatty acid delivery and fatty acid oxidation during strenuous exercise

To evaluate the extent to which decreased plasma free fatty acid (FFA) concentration contributes to the relatively low rates of fat oxidation during high-intensity exercise, we studied FFA metabolism in six endurance-trained cyclists during 20-30 min of exercise [85% of maximal O2 uptake (VO2max)]. They were studied on two occasions: once during a control trial when plasma FFA concentration is normally low and again when plasma FFA concentration was maintained between 1 and 2 mM by intravenous infusion of lipid (Intralipid) and heparin. During the 20-30 min of exercise, fat and carbohydrate oxidation were measured by indirect calorimetry, and the rates of appearance (Ra) of plasma FFA and glucose were determined by the constant infusion of [6,6-2H2]glucose and [2H2]palmitate. Lipid-heparin infusion did not influence the Ra or rate of disappearance of glucose. During exercise in the control trial, Ra FFA failed to increase above resting levels (11.0 +/- 1.2 and 12.4 +/- 1.7 mumol.kg-1.min-1 for rest and exercise, respectively) and plasma FFA concentration dropped from a resting value of 0.53 +/- 0.08 to 0.29 +/- 0.02 mM. The restoration of plasma FFA concentration resulted in a 27% increase in total fat oxidation (26.7 +/- 2.6 vs. 34.0 +/- 4.4 mumol.kg-1.min-1, P < 0.05) with a concomitant reduction in carbohydrate oxidation, apparently due to a 15% (P < 0.05) reduction in muscle glycogen utilization. However, the elevation of plasma FFA concentration during exercise at 85% VO2max only partially restored fat oxidation compared with the levels observed during exercise at 65% VO2max. These findings indicate that fat oxidation is normally impaired during exercise at 85% VO2max because of the failure of FFA mobilization to increase above resting levels, but this explains only part of the decline in fat oxidation when exercise intensity is increased from 65 to 85% VO2max.     

Overproduction of a functional fatty acid biosynthetic enzyme blocks fatty acid synthesis in Escherichia coli

beta-Ketoacyl-acyl carrier protein (ACP) synthetase II (KAS II) is one of three Escherichia coli isozymes that catalyze the elongation of growing fatty acid chains by condensation of acyl-ACP with malonyl-ACP. Overexpression of this enzyme has been found to be extremely toxic to E. coli, much more so than overproduction of either of the other KAS isozymes, KAS I or KAS III. The immediate effect of KAS II overproduction is the cessation of phospholipid synthesis, and this inhibition is specifically due to the blockage of fatty acid synthesis. To determine the cause of this inhibition, we examined the intracellular pools of ACP, coenzyme A (CoA), and their acyl thioesters. Although no significant changes were detected in the acyl-ACP pools, the CoA pools were dramatically altered by KAS II overproduction. Malonyl-CoA increased to about 40% of the total cellular CoA pool upon KAS II overproduction from a steady-state level of around 0.5% in the absence of KAS II overproduction. This finding indicated that the conversion of malonyl-CoA to fatty acids had been blocked and could be explained if either the conversion of malonyl-CoA to malonyl-ACP and/or the elongation reactions of fatty acid synthesis had been blocked. Overproduction of malonyl-CoA:ACP transacylase, the enzyme catalyzing the conversion of malonyl-CoA to malonyl-ACP, partially relieved the toxicity of KAS II overproduction, consistent with a model in which high levels of KAS II blocks access of the other KAS isozymes to malonyl-CoA:ACP transacylase.     

Electrogenicity of hepatocellular fatty acid uptake

Sensitivity of cellular fatty acids uptake to the membrane potential difference is still a matter of controversy. For direct evaluation of potential sensitivity the effect of changing membrane potential on uptake of a fluorescent long chain fatty acid derivative, 12-NBD-stearate, in isolated rat hepatocytes, was examined. Changes in membrane potential were achieved by patch clamp procedures. Fatty acid influx was simultaneously determined by recording of cell fluorescence. Hyperpolarization from -30 to -70 mV accelerated fatty acid influx whereas depolarization to +50 mV reduced uptake. After obtaining equilibrium hyperpolarization increased cell fluorescence, whereas depolarization pushed NBD-stearate out of cells. Potential sensitivity of uptake was dependent on the fatty acid concentrations in the medium with most prominent effects at low unbound concentrations. These data show that, at low fatty acid concentrations, uptake is, in part, driven by an intracellular negative electric membrane potential.     

Dietary modification of omega 6 fatty acid intake and its effect on urinary eicosanoid excretion

A group of women were fed two separate diets in a crossover study and urinary eicosanoids were quantified. One diet contained 3.1% of total energy (en%) as polyunsaturated fatty acids (3.0 en% linoleic acid) and the other contained 8.4 en% polyunsaturated fatty acids (8.3 en% linoleic acid). Carbohydrate replaced fat in the low-polyunsaturated-fat diet. No changes were observed in the urinary excretion of 6-oxo-prostaglandin F1 alpha, its 2,3-dinor metabolite or thromboxane B2 by subjects on either of the diets. Urinary 2,3-dinor-thromboxane B2 excretion was lower (206.5 ng/24 h) when subjects were fed the high-omega 6 polyunsaturated fatty acid diet when compared with the lower-omega 6 polyunsaturated fatty acid diet (275.3 ng/24 h). Conversely, urinary prostaglandin E2 was higher (139.2 ng/g creatinine) during the higher-omega 6 polyunsaturated fatty acid diet when compared with the lower-omega 6 polyunsaturated fatty acid diet (94.4 ng/g creatinine).     

Comparison of the fatty acid compositions in intraepithelial and infiltrating lesions of the cervix: part II, free fatty acid profiles

Clinical studies report a low incidence of intestinal side effects with transdermally administered fentanyl (TTS-fentanyl) in comparison with oral morphine. To support these clinical data, analgesic and intestinal effects of both opioids were compared in rats. After subcutaneous injection, analgesia in the tail withdrawal reaction test was obtained at a peak effect dose of 0.032 mg/kg with fentanyl and 8.0 mg/kg with morphine. This analgesic dose exceeded the ED50 for inhibition of castor oil-induced diarrhea only slightly (1.1 x) in the case of fentanyl (0.028 mg/kg) but markedly (36 x) in the case of morphine (0.22 mg/kg). To reverse completely the antidiarrheal effect of equivalent analgesic doses of the opioids (their ED50S for analgesia lasting 2 hours), much more naloxone was required in the case of morphine (5.4 mg/kg) than in the case of fentanyl (0.19 mg/kg). After oral administration, the difference between both opioids was less pronounced. Analgesia was obtained at 0.85 mg/kg with fentanyl and 32 mg/kg with morphine. This analgesic dose only slightly (1.7 x) exceeded the antidiarrheal dose in the case of fentanyl (0.49 mg/kg) but significantly (6.2 x) in the case of morphine (5.2 mg/ kg). To reverse completely the antidiarrheal effect of equivalent analgesic oral doses of the opioids (their ED50S for analgesia lasting 2 hours), more naloxone was required in the case of morphine (11 mg/kg) than in the case of fentanyl (2.0 mg/kg). Rapid penetration of fentanyl into the brain is thought to be responsible for small dissociation between the analgesic and intestinal effect of this lipophilic opioid. The present data provide preclinical evidence to support the relatively low incidence of intestinal side effects observed clinically with the use of TTS-fentanyl in comparison with orally administered morphine.     

Ah receptor binding properties of indole carbinols and induction of hepatic estradiol hydroxylation

The effect of route of administration on the ability of indole-3-carbinol (13C), an anticarcinogen present in cruciferous vegetables, to induce estradiol 2-hydroxylase (EH) in female rat liver microsomes was investigated and compared to that of its main gastric conversion product, 3,3'-diindolylmethane (DIM). This dimer was more potent than 13C after either oral or intraperitoneal administration and was also a better in vitro inhibitor of EH in control and 13C-induced hepatic microsomes. The induction of both CYP1A1 and 1A2 in about equal amounts by 13C and DIM as well as of CYP2B1/2 was demonstrated using monoclonal antibodies. DIM, isosafrole, beta-naphthoflavone, 3-methylcholanthrene and naringenin added in vitro inhibited EH strongly in induced microsomes but gestodene was a better inhibitor of estrogen 2-hydroxylation in liver microsomes from untreated female rats. The binding affinities of 13C and DIM to the Ah receptor were compared to that of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) by competition studies, and the IC50 values were shown to be 2.0 x 10(-9) M, 5.0 x 10(-5) M and 2.3 x 10(-3) M for TCDD, DIM and 13C, respectively. The ability of 13C or DIM to cause in vitro transformation of the Ah receptor to a form able to bind to the dioxin-responsive element-3 (DRE3) was compared to that of TCDD and shown to parallel their abilities to compete for binding of [3H]TCDD to the Ah receptor. These experiments confirm and extend the proposals that dietary indoles induce specific cytochrome P450s in rat liver by a mechanism possibly involving the Ah receptor. The induced monooxygenases, in turn, increase the synthesis of 2-hydroxylated estrogens in the competing pathways of 2- and 16 alpha-hydroxylation which decreases the levels of 16 alpha-hydroxyestrone able to form stable covalent adducts with proteins including the estrogen receptor. Such steroid-protein interaction has been correlated with mammary carcinogenesis.     

Evaluation of short-chain fatty acid enemas: treatment of radiation proctitis

BACKGROUND: Radiation proctitis is a common complication of abdominal and pelvic radiotherapy; unfortunately, there is no established effective therapy for radiation proctitis. Short-chain fatty acids (SCFA) have been effectively used to treat a variety of colitides. We sought to determine whether SCFA enemas have a role in the treatment of radiation proctitis. METHODS: Seven patients completed an open-labeled, pilot study to evaluate the effect of SCFA on clinical, endoscopic, and pathological parameters of radiation proctitis. RESULTS: Four weeks of treatment with SCFA enemas resulted in clinical improvement in all patients. There were modest, but not significant, changes in endoscopic and pathological parameters. CONCLUSION: SCFA are a promising therapeutic option in radiation proctitis.     

Effect of propionic acid on fatty acid oxidation and ureagenesis

Propionic acid significantly inhibited 14CO2 production from [1-14C] palmitate at a concentration of 10 muM in control fibroblasts and 100 muM in methylmalonic fibroblasts. This inhibition was similar to that produced by 4-pentenoic acid. Methylmalonic acid also inhibited 14CO2 production from [1-14C] palmitate, but only at a concentration of 1 mM in control cells and 5 mM in methylmalonic cells. Propionic acid (5 mM) also inhibited ureagenesis in rat liver slices when ammonia was the substrate but not with aspartate and citrulline as substrates. Propionic acid had no direct effect on either carbamyl phosphate synthetase or ornithine transcarbamylase. These findings may explain the fatty degeneration of the liver and the hyperammonemia in propionic and methylmalonic acidemia.     

Effect of endurance training on fatty acid metabolism: local adaptations

Older studies of humans seem to suggest a correlation between free fatty acid (FFA) turnover and oxidation on the one hand and plasma FFA concentration on the other hand during submaximal exercise. However, recent studies, in which higher concentrations of plasma FFA have been reached during prolonged submaximal exercise, have revealed a levelling off in net uptake in spite of increasing plasma FFA concentrations. Furthermore, this relationship between FFA concentration and FFA uptake and oxidation is altered by endurance training. These recent findings in humans support the notion from other cell types that transmembrane fatty acid transport is not only by simple diffusion, but predominantly carrier-mediated. During prolonged submaximal knee-extension exercise it has been demonstrated that the total oxidation of fatty acids was approximately 60% higher in trained subjects than in nontrained subjects. The training-induced adaptations responsible for this increased utilization of plasma fatty acids by the muscle could be located at several steps from the mobilization of fatty acids to skeletal muscle metabolism in the mitochondria. In this paper regulation at the transport steps and also at various metabolic steps is discussed.