No description available.

Diet plays an important role in the development of chronic metabolic diseases (diabetes, obesity, cardiovascular disease) and as dietary fat consumption has increased, so has the incidence of these disorders. Metabolic syndrome, a clustering of risk factors that includes central obesity, increased plasma triacylglycerol (TG), elevated fasting glucose and glucose intolerance is perhaps the most notorious and aggressive. Animal and human studies indicate that bioactive fatty acids can influence cellular energy metabolism. Using susceptible rodent models (apoE-/- and LDLr-/- mice and Syrian Golden hamsters) this project investigated whether supplementation of a western type diet (WD) with bioactive fatty acids could improve hepatic lipid metabolism, plasma lipoprotein profiles or liver markers of lipogenesis. In mice, dietary supplementation with t-10, c-12 conjugated linoleic acid (CLA) decreased the weight gain induced by high fat diet compared with WD (p<0.01) and was accompanied by hyperinsulinemia (p<0.05) in the ApoE-/- and hypoadiponectinemia (p<0.01) in both mice strains. Although t-10, c-12 CLA supplementation increased plasma lipids and was associated with profound liver steatosis there was a reduction in atherosclerotic lesions in both mouse models (p<0.05). Analysis of mRNA and protein levels in the liver suggested that the differences in liver and plasma lipids may reflect inappropriate lipogenic response to t-10,c-12 CLA. In the high fat and fructose-fed hamster, the modulating role of fish fatty acids was investigated. The addition of DHA increased weight gain and adiposity compared to EPA and c-9, t-11 CLA supplementation. However, glucose tolerance was improved after 6 weeks of DHA supplementation (p? 0.01). Using [35S]methionine radiolabelling, DHA supplementation decreased apolipoprotein B100 synthesis and secretion. Newly synthesized cellular and secreted TG, as measured by [3H]glycerol incorporation, were also decreased with DHA supplementation. Although the effects of EPA were similar to those with DHA, the magnitude was generally lower. These results suggest that supplementation with fish fatty acids can improve several of the risk factors of the metabolic syndrome. Taken together, these observations indicate that some, but not all, bioactive fatty acids may be useful supplements for mediating cardiovascular risk factors.

The FAME yield from microalgae of two in situ transesterification methods were compared to a typical Folch et al. (1957) extraction followed by transesterification using the Hilditch et al. (1964) procedure. A method based on Park & Goins (1994), utilizing 0.5 N NaOH in methanol, then 14 % BCl3 in methanol, was found to be superior to a method based on Lepage & Roy (1986), utilizing acetyl chloride in methanol. The Park & Goins (1994) method was equivalent to the traditional method and was, therefore, selected for further study. In establishing the parameters of the method, water contents up to 0.55 mL were not found to inhibit the reaction within the maximum lipid load, conservatively assessed at ~1 mg. The reaction time and temperature required to produce a maximum FAME yield was 10 min at 90 °C for the BCl3-catalyzed reaction, while the NaOH-catalyzed reaction happened instantaneously at ambient temperature.

No description available.

This study was carried out to investigate the fatty acid composition of tumoral, marginal and normal breast tissue in female breast cancer patients. Patients were recruited from St. Boniface General Hospital. A pre-operative blood sample was drawn. After surgery, sections were obtained from tumoral, marginal and normal breast tissues for histology and biochemical analysis. Extracted lipids from marginal tissue were significantly higher than those in normal or tumoral tissue. The lipid profile in tumoral tissue was significantly different in terms of fatty acid composition compared to normal and marginal tissue with less linoleic and alpha linolenic acid and more long chain polyunsaturated fatty acid of omega-3 and omega-6 series. Marginal tissue showed significantly less alpha linolenic acid compared to normal tissue. An inverse correlation existed between plasma level of 22:6 n-3 and breast cancer stage. We found different lipid profile in tumoral tissue compared to normal and marginal tissue.

The blood-brain barrier (BBB) formed by the brain capillary endothelial cells provides a protective barrier between the systemic blood and the extracellular environment of the central nervous system. Since most fatty acids in the brain enter from the blood, we examined the mechanism of permeability of various fatty acids across primary human brain microvessel endothelial cells (HBMEC). Cardiolipin (CL), a major mitochondrial phospholipid involved in energy metabolism in mammalian mitochondria, and fatty acid transport protein-1 (FATP-1) may regulate the intracellular level of fatty acyl-Coenzyme A’s. Since fatty acids are required for oxidative phosphorylation via mitochondrial oxidation, we also examined the effect of altering FATP-1 levels on CL biosynthesis. The permeability of radiolabeled fatty acids was determined using confluent cells grown on Transwell® inserts following inhibition of various fatty acid transporters. The passage of [1-14C]oleate across confluent HBMEC monolayers was significantly enhanced when fatty acid free albumin was present in the basolateral media. Knockdown of FATP-1, FATP-4, fatty acid translocase/CD36, or fatty acid binding protein 5 significantly decreased permeability of a number of radiolabeled fatty acids across the HBMEC monolayer from either apical as well as basolateral sides. The findings indicate that transport of some fatty acids across HBMEC is, in part, a transcellular process mediated by fatty acid transport proteins. Next, HEK 293 cells were used as a model to determine the effect of altering FATP-1 levels on CL. HEK-293 mock- and FATP-1 siRNA-transfected cells or mock and FATP-1 expressing cells were incubated for 24 h with 0.1 mM oleate bound to albumin (1:1 molar ratio) then incubated for 24 h with 0.1 mM [1,3-3H]glycerol and radioactivity incorporated into CL determined. FATP-1 siRNA-transfected cells exhibited reduced FATP-1 mRNA and increased incorporation of [1,3-3H]glycerol into CL (2-fold, p<0.05) compared to controls indicating elevation in de novo CL biosynthesis. In contrast, expression of FATP-1 resulted a reduction in incorporation of [1,3-3H]glycerol into CL (65%, p<0.05) indicating reduced CL synthesis. In addition, in vitro cytidine-5’-diphosphate-1,2-diacyl-sn-glycerol synthetase (CDS) activity was reduced by exogenous addition of oleoyl-Coenzyme A. The data indicate that CL de novo biosynthesis may be regulated by FATP-1 through CDS-2 expression in HEK 293 cells.

Considerable interest has focused on the influence of dietary fat quality on cardiovascular disease (CVD) risk. Increasingly, novel dietary oils rich in oleic acid and alpha-linolenic acid (ALA) are being developed and marketed with an aim to improve fatty acid intakes and reduce CVD risk. The objective of this research was to investigate the efficacy of high-oleic canola oil (HOCO) alone, or blended with flaxseed oil (FXCO), on traditional and emerging clinical biomarkers of CVD risk. An additional aim was to study the influence of dietary and genetic factors on metabolism of 13C-ALA to long-chain PUFA. Using a diet-controlled randomized crossover design, thirty-six hypercholesterolaemic subjects consumed three isoenergetic diets for 28 days each containing ~36% energy from fat, of which 70% was provided by HOCO, FXCO, or a Western dietary fat blend (WD; control). Endpoint measures revealed reductions (P<0.001) in serum lipid concentrations, including a 7.4% and 15.1% decrease in LDL-cholesterol after HOCO and FXCO diets, respectively, as compared with the WD control. Moreover, a reduction (P=0.023) in plasma E-selectin concentration was found after the FXCO diet compared with the WD control. Consumption of the dietary oils failed to alter whole-body fat oxidation or energy expenditure, nor lead to alterations in body composition. FXCO diet increased (P<0.001) plasma ALA ~5-fold, EPA ~3-fold, and DPA ~1.5-fold, but did not modulate DHA levels compared with the WD control. At 24 and 48 hours the amount of administered 13C-ALA recovered as plasma 13C-EPA and 13C-DPA was lower (P<0.001) after FXCO diet compared with HOCO and WD diets, suggesting decreased ALA conversion efficiency with very high intakes of dietary ALA. No difference in plasma 13C-DHA enrichment was observed across diets. Moreover, minor alleles of selected single nucleotide polymorphisms in the FADS1/FADS2 gene cluster were associated with reduced (P<0.05) plasma fatty acid compositions and apparent conversion of 13C-ALA. However, increased consumption of ALA in the FXCO diet compensated for lower levels of EPA in minor allele homozygotes. Taken together, substitution of dietary fats common to WD with both HOCO and FXCO represents an effective strategy to target several biomarkers for CVD risk reduction.

This study was carried out to investigate the fatty acid composition of tumoral, marginal and normal breast tissue in female breast cancer patients. Patients were recruited from St. Boniface General Hospital. A pre-operative blood sample was drawn. After surgery, sections were obtained from tumoral, marginal and normal breast tissues for histology and biochemical analysis. Extracted lipids from marginal tissue were significantly higher than those in normal or tumoral tissue. The lipid profile in tumoral tissue was significantly different in terms of fatty acid composition compared to normal and marginal tissue with less linoleic and alpha linolenic acid and more long chain polyunsaturated fatty acid of omega-3 and omega-6 series. Marginal tissue showed significantly less alpha linolenic acid compared to normal tissue. An inverse correlation existed between plasma level of 22:6 n-3 and breast cancer stage. We found different lipid profile in tumoral tissue compared to normal and marginal tissue.

The blood-brain barrier (BBB) formed by the brain capillary endothelial cells provides a protective barrier between the systemic blood and the extracellular environment of the central nervous system. Since most fatty acids in the brain enter from the blood, we examined the mechanism of permeability of various fatty acids across primary human brain microvessel endothelial cells (HBMEC). Cardiolipin (CL), a major mitochondrial phospholipid involved in energy metabolism in mammalian mitochondria, and fatty acid transport protein-1 (FATP-1) may regulate the intracellular level of fatty acyl-Coenzyme A’s. Since fatty acids are required for oxidative phosphorylation via mitochondrial oxidation, we also examined the effect of altering FATP-1 levels on CL biosynthesis. The permeability of radiolabeled fatty acids was determined using confluent cells grown on Transwell® inserts following inhibition of various fatty acid transporters. The passage of [1-14C]oleate across confluent HBMEC monolayers was significantly enhanced when fatty acid free albumin was present in the basolateral media. Knockdown of FATP-1, FATP-4, fatty acid translocase/CD36, or fatty acid binding protein 5 significantly decreased permeability of a number of radiolabeled fatty acids across the HBMEC monolayer from either apical as well as basolateral sides. The findings indicate that transport of some fatty acids across HBMEC is, in part, a transcellular process mediated by fatty acid transport proteins. Next, HEK 293 cells were used as a model to determine the effect of altering FATP-1 levels on CL. HEK-293 mock- and FATP-1 siRNA-transfected cells or mock and FATP-1 expressing cells were incubated for 24 h with 0.1 mM oleate bound to albumin (1:1 molar ratio) then incubated for 24 h with 0.1 mM [1,3-3H]glycerol and radioactivity incorporated into CL determined. FATP-1 siRNA-transfected cells exhibited reduced FATP-1 mRNA and increased incorporation of [1,3-3H]glycerol into CL (2-fold, p<0.05) compared to controls indicating elevation in de novo CL biosynthesis. In contrast, expression of FATP-1 resulted a reduction in incorporation of [1,3-3H]glycerol into CL (65%, p<0.05) indicating reduced CL synthesis. In addition, in vitro cytidine-5’-diphosphate-1,2-diacyl-sn-glycerol synthetase (CDS) activity was reduced by exogenous addition of oleoyl-Coenzyme A. The data indicate that CL de novo biosynthesis may be regulated by FATP-1 through CDS-2 expression in HEK 293 cells.

Considerable interest has focused on the influence of dietary fat quality on cardiovascular disease (CVD) risk. Increasingly, novel dietary oils rich in oleic acid and alpha-linolenic acid (ALA) are being developed and marketed with an aim to improve fatty acid intakes and reduce CVD risk. The objective of this research was to investigate the efficacy of high-oleic canola oil (HOCO) alone, or blended with flaxseed oil (FXCO), on traditional and emerging clinical biomarkers of CVD risk. An additional aim was to study the influence of dietary and genetic factors on metabolism of 13C-ALA to long-chain PUFA. Using a diet-controlled randomized crossover design, thirty-six hypercholesterolaemic subjects consumed three isoenergetic diets for 28 days each containing ~36% energy from fat, of which 70% was provided by HOCO, FXCO, or a Western dietary fat blend (WD; control). Endpoint measures revealed reductions (P<0.001) in serum lipid concentrations, including a 7.4% and 15.1% decrease in LDL-cholesterol after HOCO and FXCO diets, respectively, as compared with the WD control. Moreover, a reduction (P=0.023) in plasma E-selectin concentration was found after the FXCO diet compared with the WD control. Consumption of the dietary oils failed to alter whole-body fat oxidation or energy expenditure, nor lead to alterations in body composition. FXCO diet increased (P<0.001) plasma ALA ~5-fold, EPA ~3-fold, and DPA ~1.5-fold, but did not modulate DHA levels compared with the WD control. At 24 and 48 hours the amount of administered 13C-ALA recovered as plasma 13C-EPA and 13C-DPA was lower (P<0.001) after FXCO diet compared with HOCO and WD diets, suggesting decreased ALA conversion efficiency with very high intakes of dietary ALA. No difference in plasma 13C-DHA enrichment was observed across diets. Moreover, minor alleles of selected single nucleotide polymorphisms in the FADS1/FADS2 gene cluster were associated with reduced (P<0.05) plasma fatty acid compositions and apparent conversion of 13C-ALA. However, increased consumption of ALA in the FXCO diet compensated for lower levels of EPA in minor allele homozygotes. Taken together, substitution of dietary fats common to WD with both HOCO and FXCO represents an effective strategy to target several biomarkers for CVD risk reduction.