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Stephen C. Cunnane - One of the best experts on this subject based on the ideXlab platform.
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α linolenate reduces the dietary requirement for Linoleate in the growing rat
Prostaglandins Leukotrienes and Essential Fatty Acids, 2011Co-Authors: Philippe Guesnet, Jean Marc Alessandri, Melanie Jouin, S M Lallemand, Stephen C. CunnaneAbstract:Abstract Background : We hypothesized that due to the absence of a dietary source of omega-3 fatty acids, the essential fatty acid (EFA) deficiency model leads to an overestimate of linoleic acid (LA) requirements. Methods: over 7wk, young rats consumed an EFA diet containing either 0en% Linoleate (0LA) and 0en% α -linolenate (0LNA) or a diet containing 0.5en% LNA plus one of seven levels of added LA (0.12–4.0en%; n =6/group). Results : Rats consuming the 0LA–0LNA diet had the lowest final body weight, 34–68% lower LA and arachidonate in plasma and liver, 87% lower LA in epididymal fat, and an 8–20 fold higher eicosatrienoate in plasma, liver and muscle lipids. 0.5LNA completely prevented the lower growth and partly prevented the rise in eicosatrienoate seen in the 0LA–0LNA group. Conclusion : Providing dietary LNA at 0.5 en% reduces the rat's physiological requirement for LA by an estimated factor of at least four (0.5en% instead of 2en%). Since LA requirements in humans are also based on the same flawed model of EFA deficiency, it is plausible that they too have been overestimated and should therefore be reinvestigated.
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a comparison of the metabolism of eighteen carbon 13c unsaturated fatty acids in healthy women
Journal of Lipid Research, 2004Co-Authors: U Mccloy, Mary Ann Ryan, P B Pencharz, R J Ross, Stephen C. CunnaneAbstract:Altered use of different dietary fatty acids may contribute to several chronic diseases, including obesity, noninsulin-dependent diabetes mellitus, and cardiovascu- lar disease. However, few comparative data are available to support this link, so the goal of the present study was to compare the metabolism of ( 13 C)oleate, ( 13 C) � -linolenate, ( 13 C)elaidate, and ( 13 C)Linoleate through oxidation and in- corporation into plasma lipid fractions and adipose tissue. Each tracer was given as a single oral bolus to six healthy women. Samples were collected over 8 days, and 13 C was an- alyzed using isotope ratio mass spectrometry. At 9 h post- dose, cumulative oxidation was similar for ( 13 C)elaidate, ( 13 C)oleate, and ( 13 C) � -linolenate (19 � 1%, 20 � 4%, and 19 � 3% dose, respectively). Significantly lower oxidation of ( 13 C)Linoleate (12 � 4% dose; P � 0.05) was accompa- nied by its higher incorporation into plasma phospholipids and cholesteryl esters. Abdominal adipose tissue was en- riched with ( 13 C) � -linolenate, ( 13 C)elaidate, or ( 13 C)Linoleate within 6 h. The percentage Linoleate in plasma phospholip- ids correlated positively with ( 13 C)Linoleate and ( 13 C)elai- date oxidation, indicating a potential role of background diet. Conversion of ( 13 C)Linoleate and ( 13 C) � -linolenate to longer chain polyunsaturates was a quantitatively minor route of utilization.— McCloy, U., M. A. Ryan, P. B. Pen- charz, R. J. Ross, and S. C. Cunnane. A comparison of the metabolism of eighteen-carbon 13 C-unsaturated fatty acids in healthy women. J. Lipid Res. 2004. 45: 474-485.
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Problems with essential fatty acids: time for a new paradigm?
Progress in Lipid Research, 2003Co-Authors: Stephen C. CunnaneAbstract:Abstract The term ‘essential fatty acid’ is ambiguous and inappropriately inclusive or exclusive of many polyunsaturated fatty acids. When applied most rigidly to Linoleate and α-linolenate, this term excludes the now well accepted but conditional dietary need for two long chain polyunsaturates (arachidonate and docosahexaenoate) during infancy. In addition, because of the concomitant absence of dietary α-linolenate, essential fatty acid deficiency is a seriously flawed model that has probably led to significantly overestimating Linoleate requirements. Linoleate and α-linolenate are more rapidly β-oxidized and less easily replaced in tissue lipids than the common ‘non-essential’ fatty acids (palmitate, stearate, oleate). Carbon from Linoleate and α-linolenate is recycled into palmitate and cholesterol in amounts frequently exceeding that used to make long chain polyunsaturates. These observations represent several problems with the concept of ‘essential fatty acid’, a term that connotes a more protected and important fatty acid than those which can be made endogenously. The metabolism of essential and non-essential fatty acids is clearly much more interconnected than previously understood. Replacing the term ‘essential fatty acid’ by existing but less biased terminology, i.e. polyunsaturates, ω3 or ω6 polyunsaturates, or naming the individual fatty acid(s) in question, would improve clarity and would potentially promote broader exploration of the functional and health attributes of polyunsaturated fatty acids.
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carbon recycling into de novo lipogenesis is a major pathway in neonatal metabolism of Linoleate and α linolenate
Prostaglandins Leukotrienes and Essential Fatty Acids, 1999Co-Authors: Stephen C. Cunnane, Chantale R Menard, Sergei S Likhodii, J T Brenna, M A CrawfordAbstract:Abstract Recent reports indicate that recycling of the β-oxidized carbon skeleton of Linoleate and α-linolenate into newly synthesized cholesterol and fatty acids in the brain is quantitatively significant in both suckling rats and pre- and postnatally in rhesus monkeys. The recycling appears to occur via ketones which are not only readily produced from these 18 carbon polyunsaturates but are also the main lipogenic precursors for the developing mammalian brain. Since the neonatal rat brain appears not to acquire cholesterol or long chain saturated or monounsaturated fatty acids from the circulation, ketones and ketogenic precursors seem to be crucial for normal brain synthesis of these lipids. Cholesterol is plentiful in brain membranes and it has also been discovered to be the essential lipid adduct of the ‘hedgehog’ family of proteins, the appropriate expression of which determines normal embryonic tissue patterning and neurological development. Insufficient cholesterol or inappropriate expression of ‘sonic hedgehog’ has major adverse neurodevelopmental consequences typified in humans by Smith-Lemli-Optiz syndrome. Hence, we propose that the importance of α-linolenate and Linoleate for normal neural development arises not only from being precursors to longer chain polyunsaturates incorporated into neuronal membranes but, perhaps equally importantly, by being ketogenic precursors needed for in situ brain lipid synthesis.
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Pure Linoleate deficiency in the rat: influence on growth, accumulation of n-6 polyunsaturates, and [1-14C]Linoleate oxidation.
Journal of lipid research, 1997Co-Authors: Stephen C. Cunnane, M. J. AndersonAbstract:Essential fatty acid deficiency has been widely studied but the extent to which its effects are attributable specifically to deficiency of Linoleate as opposed to deficiency of all unsaturated fatty acids is unknown. Our objective was to evaluate the effect of pure Linoleate deficiency on growth as well as changes in the metabolism and oxidation of n-6 polyunsaturates. The diets contained 20 energy % fat blended from 3 energy % pure oleate, 2 energy % Linoleate (0.01 energy % in the Linoleate-deficient group), 0.3 energy % pure alpha-linolenate, and the balance as palmitate and stearate from fully hydrogenated soybean oil. Thirty-five-day-old rats consumed the two diets for 84 days, after which the Linoleate-deficient rats weighed 15% less than the controls (P < 0.05), had mild scaling on the paws, and visible hair loss (in a few rats). Compared with the controls, the ratio of eicosatrienoate to arachidonate after 84 days was elevated in liver (170-fold) and serum (520-fold) phospholipids of the Linoleate-deficient group. In total, Linoleate-deficient rats consumed 122 mg of Linoleate and had a net whole body loss of 479 mg n-6 polyunsaturates compared with an intake of 24,130 mg and a net whole body gain of 7206 mg n-6 polyunsaturates in the control group. Linoleate-deficient rats oxidized 1% of an oral bolus of [1-14C]Linoleate over 8 h compared with 34% in the control rats (P < 0.05). We conclude that pure Linoleate deficiency has marked effects on accumulation of n-6 polyunsaturates but induces milder gross symptoms, particularly growth retardation, than classical essential fatty acid deficiency. alpha-Linolenate and possibly oleate may have a sparing effect on Linoleate oxidation from body stores during Linoleate deficiency.
Jozef Rychly - One of the best experts on this subject based on the ideXlab platform.
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Rate constants of oxidation of unsaturated fatty esters studied by chemiluminescence
Chemistry and Physics of Lipids, 2012Co-Authors: Emmanuel Richaud, Ludmila Audouin, Bruno Fayolle, Jacques Verdu, Lyda MatisovÁ-rychlÁ, Jozef RychlyAbstract:This study deals with oxidation kinetics of three unsaturated fatty esters: methyl oleate, methyl Linoleate and methyl linolenate at temperatures ranging from 90 to 150 °C. The reaction was monitored by chemiluminescence. A kinetic model was derived from a simple mechanistic scheme, in which initiation is due to hydroperoxides decomposition, whereas propagation results from the abstraction of the most labile hydrogen and termination results only from the bimolecular combination of peroxyl radicals. Analysis of induction period duration indicated that hydroperoxides mainly decompose by a bimolecular process. The model well predicts the main features of the experimental chemiluminescence curves. Kinetic parameters of the three unsaturated fatty esters were assessed from inverse method and discussed.
Emmanuel Richaud - One of the best experts on this subject based on the ideXlab platform.
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Rate constants of oxidation of unsaturated fatty esters studied by chemiluminescence
Chemistry and Physics of Lipids, 2012Co-Authors: Emmanuel Richaud, Ludmila Audouin, Bruno Fayolle, Jacques Verdu, Lyda MatisovÁ-rychlÁ, Jozef RychlyAbstract:This study deals with oxidation kinetics of three unsaturated fatty esters: methyl oleate, methyl Linoleate and methyl linolenate at temperatures ranging from 90 to 150 °C. The reaction was monitored by chemiluminescence. A kinetic model was derived from a simple mechanistic scheme, in which initiation is due to hydroperoxides decomposition, whereas propagation results from the abstraction of the most labile hydrogen and termination results only from the bimolecular combination of peroxyl radicals. Analysis of induction period duration indicated that hydroperoxides mainly decompose by a bimolecular process. The model well predicts the main features of the experimental chemiluminescence curves. Kinetic parameters of the three unsaturated fatty esters were assessed from inverse method and discussed.
C Masson - One of the best experts on this subject based on the ideXlab platform.
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semiochemical basis of infestation of honey bee brood byvarroa jacobsoni
Journal of Chemical Ecology, 1992Co-Authors: Jerome Trouiller, Gerard Arnold, Bertrand Chappe, Yves Le Conte, C MassonAbstract:Capping of workerApis mellifera cells is elicited by four fatty acid methyl esters (Methyl palmitate, methyl oleate, methyl Linoleate, and methyl linolenate) that are present on the surface of the worker and drone larvae only a few hours before the cell is closed. The amount of the pheromone reaches its maximum value when the cell has just been capped, at 8.5 and at 10.25 days of age, respectively, for worker and drone larvae. Thereafter, the amount of the pheromone decreases to its initial level. These data suggest that the esters also have a role in the capping of the drone cells, the temporal signal allowing the worker bees to recognize the age of the larvae and then to do the appropriate behavior. Two pheromonal components, methyl palmitate and methyl linolenate, and the inactive ethyl palmitate are kairomones attractive toVarroa females. Their secretion by the larvae follows the same pattern of development as the pheromonal signal. The longer and greater kairomonal signal in drone larvae, compared to worker secretion, could explain the preference ofVarroa towards drone brood.
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Semiochemical basis of infestation of honey bee brood by Varroa jacobsoni
Journal of Chemical Ecology, 1992Co-Authors: Jerome Trouiller, Gerard Arnold, Bertrand Chappe, Yves Le Conte, C MassonAbstract:Capping of worker Apis mellifera cells is elicited by four fatty acid methyl esters (Methyl palmitate, methyl oleate, methyl Linoleate, and methyl linolenate) that are present on the surface of the worker and drone larvae only a few hours before the cell is closed. The amount of the pheromone reaches its maximum value when the cell has just been capped, at 8.5 and at 10.25 days of age, respectively, for worker and drone larvae. There after, the amount of the pheromone decreases to its initial level. These data suggest that the esters also have a role in the capping of the drone cells, the temporal signal allowing the worker bees to recognize the age of the larvae and then to do the appropriate behavior. Two pheromonal components, methyl palmitate and methyl linolenate, and the inactive ethyl palmitate are kairomones attractive to Varroa females. Their secretion by the larvae follows the same pattern of development as the pheromonal signal. The longer and greater kairomonal signal in drone larvae, compared to worker secretion, could explain the preference of Varroa towards drone brood.
Rui Curi - One of the best experts on this subject based on the ideXlab platform.
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metabolic fate and effects of saturated and unsaturated fatty acids in hep2 human larynx tumor cells
Iubmb Life, 1997Co-Authors: Alison Colquhoun, Rui CuriAbstract:Previous studies have reported the presence of carnitine palmitoyltransferase 1 and II in tumor cells and the inhibitory effects of fatty acids on cell proliferation. The present work considered the metabolic fate of [14C] or [3HI-labeled fatty acids and their effects on cellular metabolism in Hep2 human larynx tumor cells.The rate of uptake of acetate was 45% of that of myristate, paimitate, oleate, iinoleate and arachidonate. However, acetate was rapidly metabolized within the cell as seen by its low rate of accumulation as non-esterified fatty acid, <5% of that of the other fatty acids. The incorporation of fatty acids into neutral lipid fractions showed palmitate and oleate primarily entered the phospholipid fraction, while Linoleate and arachidonate entered equally the phospholipid and triacylglycerol fractions. Palmitate and oleate were oxidized to ~4CO2 at higher rates than Linoleate and arachidonate, with arachidonate being the least oxidized of the unsaturated fatty acids. Acetate was oxidized at 10-30 fold higher rates than the other fatty acids. Palmitate, oleate, Linoleate and arachidonate all had significant inhibitory effects on the rate of glucose utilization by Hep2 cells, ranging from 25-38% inhibition and were found to inhibit cell proliferation by 17-73%. These findings suggest that certain fatty acids not only play a structural role in cellular metabolism, but may also have a potential regulatory role in the glycolytic pathway of Hep2 cells.