Effects of vitamin B-6 on (n-3) polyunsaturated fatty acid metabolism.
(65/2037)
To investigate interactions between vitamin B-6 and fatty acid metabolism, male Wistar rats were fed a vitamin B-6 (B-6)-deficient diet consisting of 70% vitamin-free casein and 10% perilla oil [approximately 63% alpha-linolenic acid, (n-3)] for 5 wk. The amounts of linoleic acid (n-6) and arachidonic acid (n-6) in the B-6-deficient group changed only slightly compared with those in a pair-fed control group. The amount of linoleic acid increased and arachidonic acid decreased in the plasma total lipid fraction, and the ratios of both eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the B-6-deficient group were significantly lower than for the controls. The ratios of alpha-linolenic acid and EPA were higher, and DHA lower, in the B-6-deficient group than in the pair-fed control group in the total lipid as well as phospholipid fractions in liver microsomes. The activity of delta6-desaturase was significantly lower in the B-6-deficient group than in the pair-fed control group (approximately 64%), and acyl-CoA oxidase activity, an initial enzyme of the peroxisomal beta-oxidation pathway, was reduced by approximately 80% in the B-6-deficient group. These data suggest that B-6 deficiencies impair the metabolism of (n-3) PUFA from alpha-linolenic acid to EPA and DHA with the most pronounced reduction in the production of DHA. (+info)
Effects of dietary supplementation with n-3 fatty acids compared with n-6 fatty acids on bronchial asthma.
(66/2037)
OBJECTIVE: The effects of perilla seed oil (n-3 fatty acids) on bronchial asthma were compared with the effects of corn oil (n-6 fatty acids) in relation to the pulmonary function and the generation of leukotriene B4 (LTB4) and C4 (LTC4) by leucocytes. METHODS AND SUBJECTS: 14 asthmatic subjects were divided randomly into two groups: one group (7 subjects) consumed perilla seed oil-rich supplementation and the other group (7 subjects) consumed corn oil-rich supplementation for 4 weeks. Generation of LTs by leucocytes and respiratory function were compared between the two groups. RESULTS: The generation of LTB4 and LTC4 by leucocytes tended to increase in subjects (N=7) with corn oil-rich supplementation, and decrease in subjects (N=7) with perilla seed oil-rich supplementation. Significant differences between the two groups were observed in the generation of LTB4 at 2 weeks (p<0.05) and LTC4 at 2 weeks (p<0.05) after dietary supplementation. Significant increases in the value of PEF (p<0.05), FVC (p<0.01), FEV(1.0) (p<0.05) and V(25) (p<0.05) were found in subjects who received perilla seed oil supplementation for 4 weeks. And significant differences in the value of FVC (p<0.05) and FEV(1.0) (p<0.05) were observed between the two groups after 4 weeks of dietary supplementation. CONCLUSION: These results suggest that perilla seed oil-rich supplementation is useful for the treatment of asthma in terms of suppression of LTB4 and LTC4 generation by leucocytes, and improvement of pulmonary function. (+info)
Digestion of fat does not differ in growing pigs fed diets containing fish oil, rapeseed oil or coconut oil.
(67/2037)
We studied the digestion of fat and fatty acids in diets containing oils with different fatty acid composition. Four barrows (initial weight 35 kg) were fitted with a simple T-cannula at the terminal ileum. Three wheat starch and fish meal-based diets were formulated to contain either 150 g fish oil, rapeseed oil or coconut oil/kg. A basal diet, which did not contain oil, was also prepared. The diets were fed according to a 4 x 4 Latin square design. Each experimental period comprised 5 d adaptation to the diets, 3 d fecal collection and 2 d digesta collection. The apparent ileal and fecal digestibilities of fat were relatively high (88 - 93%). The ileal digestibilities of total, saturated and monounsaturated fatty acids did not differ among the diets. However, the digestibilities of polyunsaturated fatty acids (PUFA) in the fish and rapeseed oil diets were higher (P < 0.05) than in the coconut oil diet. The ileal digestibilities of 18:1, 18:2 and 18:3 in the rapeseed oil diet ranged from 94 to 97%. The ileal digestion of the unsaturated long-chain fatty acids 20:5(n-3) and 22:6(n-3) in the fish oil diet was nearly complete (97 - 98%). Apparent fecal digestibilities of saturated fatty acids (76 - 89%) were lower than apparent ileal digestibilities (89 - 94%). The digestibilities of fat and fatty acids were relatively high when pigs were fed diets containing fish oil, rapeseed oil or coconut oil. There were few differences in the digestibilities of saturated, monounsaturated and PUFA in the fish oil, rapeseed oil or coconut oil diets. (+info)
Development and evaluation of a model predicting the survival of Escherichia coli O157:H7 NCTC 12900 in homemade eggplant salad at various temperatures, pHs, and oregano essential oil concentrations.
(68/2037)
Homemade eggplant salad, a traditional Greek appetizer, was inoculated with Escherichia coli O157:H7 NCTC 12900 supplemented with different concentrations of oregano essential oil (0.0, 0.7, 1. 4, and 2.1% [vol/wt]) and stored at different temperatures (0, 5, 10, and 15 degrees C). The product's pH was adjusted to 4.0, 4.5, or 5. 0 with lemon juice. For each combination of the environmental factors, the bacterial counts were modeled, using the Baranyi model, as a function of time to estimate the kinetic parameters of the pathogen. A reduction of more than 1 log unit in E. coli O157:H7 counts was observed in all cases, and the death rate depended on the pH, the storage temperature, and the essential oil concentration. Separate quadratic models were developed with natural logarithms of the shoulder period and death rate as estimated by the growth model, as a function of temperature, pH, and oregano essential oil concentrations. These were further used to predict the population of E. coli O157:H7 NCTC 12900 from other inoculated eggplant salads at random conditions of temperature, pH, and oregano oil concentration. The predicted values were compared with viable-count measurements for validation. (+info)
Transport mechanism and metabolism of olive oil hydroxytyrosol in Caco-2 cells.
(69/2037)
3,4-dihydroxyphenylethanol (hydroxytyrosol; DPE) is the major phenolic antioxidant present in extra virgin olive oil, either in a free or esterified form. Despite its relevant biological effects, no data are available on its bioavailability and metabolism. The aim of the present study is to examine the molecular mechanism of DPE intestinal transport, using differentiated Caco-2 cell monolayers as the model system. The kinetic data demonstrate that [(14)C]DPE transport occurs via a passive diffusion mechanism and is bidirectional; the calculated apparent permeability coefficient indicates that the molecule is quantitatively absorbed at the intestinal level. The only labelled DPE metabolite detectable in the culture medium by HPLC (10% conversion) is 3-hydroxy-4-methoxyphenylethanol, the product of catechol-O-methyltransferase; when DPE is assayed in vitro with the purified enzyme a K(m) value of 40 microM has been calculated. (+info)
The plastidic phosphoglucomutase from Arabidopsis. A reversible enzyme reaction with an important role in metabolic control.
(70/2037)
An Arabidopsis cDNA (AtPGMp) encoding the plastidic phosphoglucomutase (PGM) predicted a 623-amino acid protein with an N-terminal sequence typical of a plastid signal peptide. Expression of a recombinant protein in Escherichia coli confirmed its enzyme activity. The recombinant enzyme had an apparent K(m) value of 98.5 microM and a V(max) of 4.48 micromol min(-1) (mg protein)(-1). The Calvin cycle intermediates fructose-1,6-bisphosphate and ribulose-1, 5-bisphosphate exerted an inhibitory effect on PGM activity, supporting its proposed involvement in controlling photosynthetic carbon flow. A point mutation was identified in the AtPGMp gene of the Arabidopsis pgm-1 mutant. The mutation in the mutant transcript generated a stop codon at about one third of the wild-type open reading frame, and thus rendered the polypeptide nonfunctional. Storage lipid analysis of the pgm-1 mutant seeds showed a 40% reduction in oil content compared with that of wild type. Our results indicate that plastidic PGM is an important factor affecting carbon flux in triacylglycerol accumulation in oilseed plants, most likely through its essential role in starch synthesis. (+info)
In vitro cellular effects of perfluorochemicals correlate with their lipid solubility.
(71/2037)
Preclinical studies comparing perflubron partial liquid ventilation with conventional mechanical ventilation have indicated that perflubron partial liquid ventilation may exert some anti-inflammatory effects. To assess whether these effects were related to the lipid solubility properties of perflubron rather than to nonspecific biophysical properties of the perfluorocarbon (PFC) liquid phase, we studied the effects of PFCs with varying lipid solubilities on the platelet aggregation response to various procoagulants and the erythrocyte hemolytic response to osmotic stress. In both cases, the degree of the response was directly related to the lipid solubility of the PFC. All the perflubron content of erythrocytes was found to be associated with the membrane compartment. The time to reach a maximum effect on hemolysis with perflubron was relatively slow (2-4 h), which paralleled the time for perflubron to accumulate in erythrocyte membranes. The rate and extent of perflubron partitioning into lecithin liposomes were similar to those of erythrocyte membranes, supporting the hypothesis that perflubron was partitioning into the lipid component of the membranes. Thus some of the potential modulatory effects of perflubron on excessive inflammatory responses that occur during acute lung injury and acute respiratory distress syndrome may be influenced in part by the extent of PFC partitioning into the lipid bilayers of cellular membranes. (+info)
Effect of dietary fish oil on the sensitivity of hepatic lipid metabolism to regulation by insulin.
(72/2037)
The contribution of dietary fat content and type to changes in the sensitivity of hepatic lipid metabolism to insulin was studied in primary hepatocyte cultures from donor rats maintained on a low-fat diet (LF), or on diets enriched in olive oil (OO) or fish oil (FO). The higher rate of fatty acid oxidation in hepatocytes from the FO-fed group was resistant to the inhibitory effects of insulin observed in hepatocytes from the other groups. Insulin stimulation of fatty acid incorporation into triglyceride (TG) was also less pronounced in hepatocytes from the FO-fed group than in those from the OO-fed group but there was no difference in the stimulatory effect of insulin on fatty acid incorporation into phospholipid (PL) in these two groups. In the case of fatty acid incorporation into both PL and TG, hepatocytes from the LF group were refractory to stimulation by insulin. At each concentration of insulin, hepatocytes from the FO-fed group secreted less very low density lipoprotein (VLDL) TG than those from the other groups. However, the absolute suppression of VLDL TG secretion by insulin was similar irrespective of the diet of the donor animals.We conclude that chronic consumption of a particular type of dietary fat does not affect the insulin sensitivity of the major pathways of hepatic lipid metabolism in a consistent manner. (+info)