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Barton, Louise Marie. "Polyunsaturated fatty acids and adrenal steroidogenesis." Thesis, Royal Veterinary College (University of London), 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.519549.
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O'Keeffe, Majella. "New sources of polyunsaturated fatty acids." Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54727/.
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Two groups of essential fatty acids (n-6 and n-3) are needed in a healthy human diet. Current advice suggests an optimal ratio of about 4:1 for these polyunsaturated fatty acids (PUFAs) in the diet but in Western countries it is usually 10-20:1. The n-3 PUFAs are synthesized in photosynthetic organisms from where they move up the food chain. Fish in particular, are a rich source of twenty and twenty two carbon n-3 PUFAs which are particularly effective for humans. Fish oils have been shown to be beneficial in a variety of chronic inflammatory diseases. However, fish stocks arc under threat. Therefore, fish farming has increased recently and offers some opportunities for viable sources of n-3 PUFAs, especially since disposal of fish farm waste is expensive and environmentally problematic. In this project, we investigated trout (
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Pinto, Eva. "Polyunsaturated fatty acids and immune cell functions." Thesis, University of Greenwich, 2007. http://gala.gre.ac.uk/6268/.
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In MS patients there was a significantly positive relationship between membrane AA and TGF-ß1 indicating that it is the individual long chain (LC) PUFA, i.e. AA that regulate the levels of TGF-ß1. Investigation of the effects of n-6 and n-3 PUFAs on normal healthy PBMC production of TGF-ß1 in vitro showed that PBMC in the presence of phytohaemaglutinin (PHA) supplemented with LA, dihyomo-?-linolenic (DGLA) and arachidonic acid (AA) significantly increase TGF-ß1 compared with non-supplemented PHA-stimulated PBMCs. In contrast, TGF-ß1 levels from PHA-stimulated PBMCs supplemented with a-linolenic (ALA), eicosapentaenoic (EPA) or docosahexaenoic acid (DHA) were significantly decreased suggesting that n-6 fatty acids (LA, DGLA and AA) increase in vitro TGF-ß1 production by PHA-stimulated PBMCs and, in contrast, n-3 fatty acids (ALA, EPA and DHA) decrease TGF-ß1 production. GLA-rich borage oil supplementation resulted in significantly decreased ex vivo monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-1a (MIP-1a) and interleukin-8 (IL-8) production from PHA-or LPS-stimulated PBMC compared with baseline. It also significantly decreased cell surface expression of CD36+, CD54+ and CD62L+ on monocytes. In contrast, there was no association between LA-rich corn oil and these adhesion molecules and chemokines suggesting that GLA and/or its metabolites are affecting the chemokines and adhesion molecules studied. Overall, results of this study indicate that n-6 long chain PUFAs may have anti-inflammatory properties and might therefore be beneficial in multiple sclerosis, atherosclerosis and other inflammatory diseases.
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Hudson, Elizabeth A. "Polyunsaturated fatty acids in tumour-induced cachexia." Thesis, Aston University, 1993. http://publications.aston.ac.uk/12600/.
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A transplantable murine colon adenocarcinoma (MAC16) was utilised as a model of human cancer cachexia. This tumour has been found to produce extensive weight loss, characterised by depletion of host body protein and lipid stores at a small tumour burden. This weight loss has been found to be associated with production by the tumour of a lipolytic factor, activity of which was inhibited in vitro by the polyunsaturated fatty acid (PUFA) eicosapentaenoic acid (EPA). EPA has also been shown to possess anti-tumour and anti-cachectic activity in vivo, leading to the hypothesis that fatty acids mobilised by the lipolytic factor supply a growth requirement of the MAC16 tumour. In this study mobilisation and sequestration of fatty acids by the tumour was found to be non-specific, although a relationship between weight loss and arachidonic acid (AA) concentration was found in both tumour-bearing mice, and human cancer patients. The anti-tumour effect of EPA, which was found to be associated with an increase in cell loss, but not its anti-cachectic activity, was reversed by the administration of the PUFAs oleic acid (OA) and linoleic acid (LA). LA was also found to be capable of stimulating tumour growth. Inhibition of either the cyclooxygenase or lipoxygenase pathways was found to result in reduction of tumour growth, leading to the implication of one of the metabolites of LA or AA in tumour growth and cachexia. The ethyl ester of EPA was found to be inactive against the growth and cachexia of the MAC16 tumour, due to its retarded uptake compared with the free acid. The anti-proliferative agent 5-fluorouracil was found to cause tumour growth inhibition, and when given in combination with EPA, reduced the phase of tumour regrowth observed after 4 to 5 days of treatment with EPA.
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Wang, Yanwen. "Omega-3 polyunsaturated fatty acids and chicken immunity." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ60356.pdf.
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Huang, Zhi Hua. "Regulation of macrophage functions by polyunsaturated fatty acids /." Adelaide, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phh8743.pdf.
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Börjesson, Sara. "Polyunsaturated Fatty Acids Modifying Ion Channel Voltage Gating." Doctoral thesis, Linköpings universitet, Cellbiologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-68084.
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Voltage-gated ion channels play fundamental roles in neuronal excitability and therefore dysfunctional channels can cause disease. Epilepsy is such a disease, affecting about 1% of the population and being characterized by synchronous electric activity of large groups of neurons leading to various types of seizures. In this thesis, polyunsaturated fatty acids (PUFAs) were used as key substances to study a new pharmacological mechanism for how to induce opening of voltage-gated potassium (Kv) channels, and how this possibly can protect against epileptic activity. All experiments were performed on cloned Shaker Kv channels expressed in Xenopus laevis oocytes. Channel activity was recorded with the electrophysiological two-electrode voltage clamp technique. First we showed that both PUFAs and cerebrospinal fluid from children on the ketogenic diet open the Shaker Kv channel by shifting the channel voltage dependence towards more negative voltages, as we would expect for an antiepileptic effect. By testing fatty acids and related compounds with different properties and under different conditions we identified the critical structural components needed for the beneficial effect: a flexible cis-polyunsaturated lipid tail in combination with a negatively charged carboxyl head group. If substituting the negative charge for a positive amine group, channel opening was instead impeded. By mutating and modifying the channel at strategic positions the PUFA-action site was localized to a lipid-exposed surface close to the channel’s voltage sensor. We also showed that PUFAs induce channel opening by electrostatically facilitating a final voltage-sensor movement. The PUFA efficiency is dependent on the channel’s profile of charged residues in the outer end of the voltage sensor. This implies channel-specific effects. Finally, computer simulations demonstrated that small changes in channel voltage dependence can have dramatic effects on cellular excitability. Both the identified PUFA-action site and the mechanism by which PUFAs induce channel opening are novel and could potentially be very useful in future drug design of compounds targeting neuronal and cardiac excitability. Our work also suggests that PUFA-induced Kv channel opening could be one important component in the ketogenic diet used as alternative epilepsy treatment.
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Abd, Elrazak Ahmed Abdo Ahmed. "Production of polyunsaturated fatty acids from marine microorganisms." Thesis, University of Newcastle Upon Tyne, 2012. http://hdl.handle.net/10443/1786.
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Polyunsaturated Fatty Acids (PUFAs), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are increasingly attracting scientific attention due to their significant health promoting role in the human body. However, the human body lacks the ability to produce them in vivo. The limitations associated with the current sources of ω-3 fatty acids and ω-6 fatty acids from animal and plant sources have led to increased interest in microbial production. Marine bacteria provide a suitable alternative, although the isolation of production strains and the identification of operating conditions must be addressed before manufacturing processes become economically viable. Sea sediment samples were collected from three different environments including Mid Atlantic Ridge, Red Sea and Mediterranean Sea. The isolates were screened for PUFA production using a fast colourimetric method and verified by gas chromatography/mass spectroscopy. The isolated PUFA producers were characterised and identified on the basis of 16S rRNA gene sequencing and analysis. Three different isolates were chosen for this study. These were labelled as 717, 66 and Hus-27. The chosen isolates were subjected to an optimisation study to maximise their productivity. This optimisation strategy included identifying a suitable production medium by applying a statistical design of experiment methodology (Plackett-Burman and Central Composite Design). A chemically defined media was identified for isolates 717 and 66 in order to determine the limiting media components and to study the effect of carbon/nitrogen ratio on the productivity of isolates. As an important step in the process development of the microbial PUFA production, the culture conditions at the bioreactor scale were optimised for isolate 717 using a Response Surface Methodology (RSM) revealing the significant effect of temperature, dissolved oxygen and the interaction between them on the EPA production. Two sets of continuous stirred-tank reactor (CSTR) experiments were also performed to test the effect of growth rates on EPA production and the effect of temperature at constant growth rate as this was identified as the most significant factor affecting EPA production. This optimisation strategy led to a significant increase in the amount of EPA produced by isolates under investigation, where the amount of EPA increased from 9 mg/g biomass, 33 mg/l representing 7.6% of the total fatty acids to 45 mg/g, 350 mg/l representing 25% of the total fatty acids using isolate 717. A significant increase was also achieved using isolate 66 with the amount of EPA increased from 5.5 mg/g, 14 mg/l representing 3.5% of the total fatty acids to 32 mg/g, 285 mg/l representing 15% of the total fatty acids. For isolate Hus-27 the amount of EPA increased from 0.6 mg/g, 3 mg/l representing 2.2% of the total fatty acids to 8 mg/g, 36 mg/l representing 8% of the total fatty acids. The stability of the produced oil and the complete absence of heavy metals in bacterial biomass are considered as an additional benefit of bacterial EPA compared to other sources of PUFA. To our knowledge this is the first report of a bacterial isolate producing EPA with such high yields making large scale manufacture much more economically viable.
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Kew, Samantha. "Fatty acids and the immune system : dose response studies with n-3 polyunsaturated fatty acids." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396188.
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Williams, Anest. "Lipid profilling of polyunsaturated fatty acid - treated mouse brain and plasma. Investigation into polyunsaturated fatty acid (PUFA)-induced neuroprotection." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4414.
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Pre-treatment with polyunsaturated fatty acids or bioactive lipid mediators has been shown to reduce neuronal injury in rodent models of focal ischaemia, but the molecular mechanisms underlying this neuroprotection are unclear. In this study, we aimed to investigate whether systemic administration of alpha linolenic acid (ALA) leads to changes in the profile of mouse brain phospholipid and bioactive lipid mediators in both mouse brain and plasma within the previously determined neuroprotection time window. Mass spectrometry (MS) and tandem mass spectrometry (MS/MS) allowed us to detect and identify 47 phospholipids in mouse cerebral cortex, including several phospholipid species not previously reported in brain lipidomic studies. These included a phosphatidylethanolamine species with m/z 720 that has been associated with retinal stem cells. No widespread changes in cerebral cortex phospholipid composition were observed following intravenous ALA. Several significant changes in lipid mediators (P<0.05 with two-way ANOVA and post hoc Dunnett's t test) were detected in ALA-treated animals compared to untreated and vehicle-injected animals. Many of the affected lipid mediators are ligands for prostanoid receptors which have been demonstrated to play a role in the development of brain injury following cerebral ischaemia, implying that changes in bioactive lipid mediators or modulation of prostanoid receptors may occur following ALA pre-treatment in mice. This study illustrates the potential of advanced lipidomic analysis as a novel tool for neurochemists.
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Funk, Colin D. "The metabolism of polyunsaturated fatty acids by vascular tissue /." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=72056.
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Blood vessels convert arachidonic acid to prostacyclin (PGI(,2)), which is a potent inhibitor of platelet aggregation and thrombus formation. Polyunsaturated fatty acids (PUFA) or their hydroperoxy metabolites can cause a reduction in PGI(,2) production. Therefore, in the present study, the metabolism of PUFA and their effects on PGI(,2) production have been investigated.Linoleic acid is converted by aorta to hydroperoxy metabolites, which are either dehydrated to oxo compounds, reduced to monohydroxy products, or converted to epoxyhydroxy-octadecenoic acids. The latter are then hydrolyzed to trihydroxy metabolites by aortic epoxide hydrolases. Aorta also converts eicosatrienoic acid to similar products, which are formed via 12-hydroperoxy-8,10-heptadecadienoic acid.
GC-MS analysis indicated that the major oxygenated PUFA metabolite formed by rat and bovine blood vessels was 6-oxoprostaglandin-F(,1(alpha)). Substantial amounts of free and esterified monohydroxy and trihydroxy metabolites of linoleic acid were detected, especially in rat and rabbit aortae. Reduction of glutathione peroxidase activity by administration of a selenium-deficient diet had no significant effect on the formation of any of the above products.
The presence of esterified monohydroxy and trihydroxy PUFA metabolites in aortic lipids indicates that their esterified hydroperoxy precursors are present. An excess of these products could inhibit PGI(,2) synthesis and contribute to the onset of atherosclerosis.
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Browning, L. "n-3 polyunsaturated fatty acids, insulin sensitivity and inflammation." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.597025.
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Obesity increases the risk of disease and inflammation may be an important mediator of this association. This thesis describes a series of studies that have investigated the relationship between obesity and its co-morbidities, using dietary fatty acids to modulate inflammatory status. Study 1 investigated the stability of a number of inflammatory markers used to characterise habitual inflammatory status in two populations of overweight and obese subjects. Results showed that sialic acid was the most stable representative marker of habitual inflammatory status, showing less variability than more commonly used markers such as C-reactive protein (CRP) and fibrinogen. This has important implications for future studies that characterise inflammatory status and relate inflammation to disease risk. Study 2 describes a cross-sectional analysis of 261 overweight and obese women where features of the metabolic syndrome were related to sialic acid and CRP. Sialic acid and CRP were univariately related to individual features of the metabolic syndrome. Sialic acid showed an incremental association with the number of features of the metabolic syndrome after adjustment for body mass index (BMI). CRP was strongly associated with BMI and did not independently predict features of the metabolic syndrome. This study showed that sialic acid identifies a group at risk of the metabolic syndrome independent of BMI. Study 3 was a crossover nutritional intervention study designed to test whether habitual inflammatory status influenced the impact of a dietary intervention. Subjects with a raised background inflammatory status at baseline showed a significant improvement in insulin sensitivity with 12 weeks n-3 polyunsaturated fatty acid intervention. These results show a small but significant improvement in insulin sensitivity with n-3 polyunsaturated fatty acid supplementation and that those individuals at the highest risk of metabolic syndrome derive the most benefit from intervention.
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Lounds, Christopher. "The production of polyunsaturated fatty acids by Mortierella alpina." Thesis, University of Nottingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.416722.
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Gonçalves, Carla Aguiar. "The role of polyunsaturated fatty acids in bacterial pathogenesis." Master's thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/13794.
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Mestrado em BiotecnologiaPolyunsaturated fatty acids (PUFAs) comprise a class of essential micronutrients, which are essential for normal development, cardiovascular health, and immunity. The role of lipids, including long-chain fatty acids, in the immune response is increasingly being recognized as beneficial regulators of the immune systems. However, the mechanisms by which PUFAs modulate innate immunity are yet to be fully clarified. C. elegans has been used in several recent studies as a simple animal model for the study of host-pathogen interactions, generating important insights into both bacterial pathogenesis and host innate immunity. Many of the virulence mechanisms used by bacterial pathogens to cause disease in mammalian hosts have also been shown to be important for pathogenesis in C. elegans and, similarly, important features of the host innate immunity have been evolutionarily conserved between C. elegans and mammals. This project is focused on addressing the role of polyunsaturated fatty acids in bacterial pathogenesis using C. elegans as model system. We find that knockdown of some elongase genes increase the worms’ susceptibility towards infection with the adherent-invasive Escherichia Coli LF82, isolated from a patient suffering from Crohn’s disease. Moreover, dietary supplementation with the fatty acid γ-linolenic acid rescued the enhanced pathogen susceptibility of C. elegans lacking a Δ6 desaturase. The fatty acid profile of the nematode is altered upon infection with pathogenic LF82. qRT-PCR analysis allowed to determine that stress and autophagy genes are induced in C. elegans infected with this particular type of E. coli. Autophagy was found to be increased on C. elegans challenged with LF82, as determined by fluorescence microscopy. Collectively these results suggest an important role for PUFAS in the innate immune response and indicate that autophagy may have a contribution for C. elegans response towards the pathogen E. coli LF82.
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Ren, Hui Xia. "Neuroprotection of ω-3 polyunsaturated fatty acids in brain disorders." Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3953276.
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Kune, Daniel. "Extraction and purification of polyunsaturated fatty acids from marine algae." Thesis, Imperial College London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406588.
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Greupner, Theresa [Verfasser]. "Metabolism of polyunsaturated fatty acids and their oxylipins / Theresa Greupner." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2019. http://d-nb.info/1179909585/34.
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Kawasima, Hiroshi. "MICROBIAL METABOLISM AND PRODUCTION OF C-20 POLYUNSATURATED FATTY ACIDS." Kyoto University, 1997. http://hdl.handle.net/2433/202405.
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Schwerbrock, Nicole M. J. Beck Melinda A. "Dietary polyunsaturated fatty acids modulate immunity to influenza virus infection." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2009. http://dc.lib.unc.edu/u?/etd,2437.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2009.Title from electronic title page (viewed Sep. 3, 2009). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Nutrition." Discipline: Nutrition; Department/School: Public Health.
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Augood, Cristina. "Association of polyunsaturated fatty acids with age-related macular degeneration." Thesis, London School of Hygiene and Tropical Medicine (University of London), 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.536759.
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Mulchandani, M. A. "Role of membrane essential polyunsaturated fatty acids in schizophrenia outcome." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2001. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2740.
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Cooper, Sarah Louise. "Dietary manipulation of the fatty acid composition of sheep meat." Thesis, Open University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252388.
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Rodrigues, Ana Sofia de Figueiredo. "Industrial production of omega-3 polyunsaturated fatty acids from fish oil and microalgae." Master's thesis, ISA/UTL, 2012. http://hdl.handle.net/10400.5/5257.
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Mestrado em Engenharia Alimentar - Instituto Superior de Agronomiaω-3 polyunsaturated fatty acids (PUFAs) ingredients, especially eicosapentaenoic acid (EPA, 20:5ω3) and docosahexaenoic acid (DHA, 22:6ω3) are known for its vital and unique role in human health and well-being by an extensive scientific research. These facts are widely spread by media. At present, the major source of ω-3 PUFAs is fish oil from oily fish like sardine (Sardina pilchardus). This work proposes the use of heterotrophic microalgae such as Crypthecodinium cohnii as an alternative source of interest for the commercial production of ω-3 EPA and DHA. It is also suggested the use of a common process suitable for both feedstock. EPA and/or DHA production are accomplished through oil saponification and PUFAs concentration winterization and urea concentration. PUFAs purification by chromatography is only necessary when oil is extracted from fish since fractions obtained from C. cohnii have high proportions in DHA and they do not require further purification steps for food applications. The combination of traditional (seasonal) and alternative sources (year-round) using a common production process shows an economic advange with increasing earnings for market development.
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Purwaha, Preeti. "Effect of Dietary Omega-3 and Omega-6 Polyunsaturated Fatty Acids on Alcoholic Liver Disease." Diss., North Dakota State University, 2012. https://hdl.handle.net/10365/26488.
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PUFAs have been shown to modulate ALD by several mechanisms, including free radical generation from hepatic lipid peroxidation. However, how they modulate lipid peroxidation and generation of bioactive metabolites in ALD is poorly understood and it is still not clear which PUFAs (?-3 or ?-6) are beneficial or detrimental in ALD. Thus, our objective was to study the effect of ?-3/?-6 PUFAs on lipid peroxidation and ethanol mediated steatosis and inflammation. Using standard liquid diet (LDC), LDC with fish oil (rich in ?-3) and safflower oil (rich in ?-6), we studied the generation of bioactive metabolites, such as eicosanoids and free radicals generated via lipid peroxidation. In addition, we determined the effect of PUFAs on several inflammatory and fibrotic factors, e.g. gene as well as protein expression, using western blot and RT-PCR, respectively. We also investigated the effect of PUFA diets on novel targets, such as hepatic membrane transporters with potential role in liver inflammation. Our results suggest that ?-3 diet prevented while ?-6 based diets promoted the development of fatty liver and inflammation. ?-3 PUFA reduced AA-peroxidation by lowering hepatic AA concentration and expression of peroxidation enzymes, COX-2 and 5-LOX, resulting in lower generation of pro-inflammatory AA-derived PGs (Series-2), HETEs and free radicals, along with increase in anti-inflammatory EPA and DHA-derived PGs (Series-3). ?-3 diet might also reduce liver inflammation by preventing activation of NF-?B and induction of TNF-?. Rats fed with ?-3 diet showed high protein expression of efflux transporters, MRP-2 and ABCA1, indicating elimination of peroxidation metabolites and triglycerides from the liver and decreased inflammation. In contrast, ?-6 diets led to increase in AA-peroxidation and generation of AA-derived pro-inflammatory metabolites. ?-6 based diets also promoted fatty liver and inflammation by activating NF-?B, inducing TNF-? and downregulation of efflux transporters, MRP-2 and ABCA1. This study not only provides new insights into the effects and possible mechanisms by which ?-3 and ?-6 PUFAs may alter hepatic steatosis and inflammation, but also put forward new targets of research, such as hepatic membrane transporters in relation to liver pathology in ALD.
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O'Shea, Karen Michelle. "Omega-3 Fatty Acids and Heart Failure." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1258128805.
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Ismail, F. M. D. "Inhibition of lipid autoxidation in amphipathic systems." Thesis, University of Salford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234723.
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Logue, James Andrew. "The adaptive effects of acyl chain unsaturation on the physical properties of biological membranes." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.321251.
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Kandando, Rihupisa Justus. "The physico-chemical properties of the Namibian pelagic fishes and seaweed polysaccharides." Thesis, University of Surrey, 1997. http://epubs.surrey.ac.uk/844582/.
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Fish provides a major source of proteins and polyunsaturated fatty acids which are known to prevent coronary heart diseases. However, inherent characteristics such as colour and texture prevent the effective utilisation of some fish, especially fatty pelagics for human consumption. Instead, they are used for fish oil and fish meal production. For this reason and for enhancing the utilisation of valuable resources, the physico-chemical properties, which may be species specific, were investigated in relation to two Namibian species, namely, horse mackerel (Trachurus capensis) and snoek (Thyrsites atun). The results showed that horse mackerel (Trachurus capensis) and snoek (Thyrsites atun) contain high contents of palmitic acids (29%), oleic acids (25%), and the omega-3-polyunsaturated fatty acids, such as docosahexaenoic acids (DHA) (15%) and eicosapentaenoic acids (EPA) (9%). The studies also showed that optimum protein extractability was obtained with 5% NaCl at pH 7.2 and the highest gel strength at pH 6.5-7.0. CaCO3 had detrimental effect on the water-holding capacity when used above 50mg.l-1 in washing water. Agar and sodium alginate extracted from Namibian Gracilaria verrucosa (red seaweed) and Laminaria schinzii (brown seaweed) respectively, were also characterised for their physico-chemical properties. Both the nontreated and treated agars were observed by colorimetric method to contain low levels of sulphate, an observation also confirmed by NMR and Raman FTIR spectroscopy. Sodium alginate was found to contain high content of guluronic acid (75%) by NMR, a good index of strong gelling ability. The good functionalities obtained as a result of optimising the physicochemical properties of fish proteins and seaweed polysaccharides enabled an investigation of the interactions of the two components. Studies on the interactions of the both horse mackerel and snoek with either sodium alginate or agar were undertaken by rheology, differential scanning calorimetry and phase contrast microscopy. Large deformation and small deformation rheological studies showed a decrease in the gel strength of fish proteins with the addition of either polysaccharide at all combinations. The DSC results indicated a lowering of the denaturation temperature with the addition ratios of increasing amounts of sodium alginate to fish proteins. Although the mixture of fish proteins and agar resulted in the lowering of the denaturation temperature, the shift; was not as pronounced as that obtained with sodium alginate. The reason for the lowering of gel strength and G' values was attributed to phase separation of fish proteins and polysaccharides which was reflected by phase contrast microscopy studies. This investigation has resulted in the characterisation of valuable fish and seaweed polysaccharide resources from Namibia which could be used in combination for the development of new food products.
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Bell, John Gordon. "Influences of dietary polyunsaturated fatty acids on tissue fatty acid composition and eicosanoid production in Atlantic salmon (Salmo salar)." Thesis, University of Stirling, 1996. http://hdl.handle.net/1893/26665.
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1. The literature has been reviewed with respect to the dietary intake and subsequent metabolism of polyunsaturated fatty acids (PUFA), of both the n-6 and n-3 series, in teleost fish. Particular emphasis has been made to the physiological roles of PUFA with respect to cell membrane function and eicosanoid production. 2. Atlantic salmon post-smolts were fed practical-type diets, based on fish meal, in three separate dietary experiments of 10-16 weeks duration. The first trial compared dietary lipid supplied either as fish oil (FO) or as sunflower oil (SO) with the diets having an n-3/n-6 PUFA ratio of 9.4 and 0.2 respectively. The second trial used diets formulated with blends of FO, SO, grape seed oil and safflower oil to provide linoleic acid at 10, 25 and 45% of total dietary fatty acids. The third trial was similar to the first but with an additional diet in which the lipid component was supplied by linseed oil (LO). All diets satisfied the nutritional requirements of salmonid fish for n-3 PUFA. There were no statistically significant differences in final weights between dietary treatments in the third trial. However, in the second trial fish fed the intermediate level of linoleic acid (25%) attained a significantly higher final weight compared to both other treatments while fish fed the highest level of linoleic acid (45%) had significantly lower final weights compared to both other treatments. In the first trial the effect of diet on growth (weight gain) could not be ascertained as the initial weights of the fish were significantly different. 3. A number of fish fed SO developed severe cardiac lesions which caused thinning of the ventricular wall and heart muscle necrosis. In addition the fish fed diets containing SO were susceptible to a transportation-induced shock syndrome that resulted in 30% mortality. 4. Incorporation of linoleic acid (18:2n-6) into membrane phospholipids increased in response to dietary intake with fish fed SO having increased levels of 18:2n-6 (up to 15-fold), 20:2n-6 (up to 12-fold), 20:3n-6 (up to 25-fold) and arachidonic acid (AA; 20:4n-6) (up to 3-fold), and decreased levels of eicosapentaenoic acid (EPA; 20:5n-3) (up to 3-fold). The ratio of n-3/n-6 PUFA was decreased (up to 4-fold) and the20:4n-6/20:5n-3 ratio increased (up to 9-fold) in membrane phospholipids from fish fed SO compared to those fed fish oil. While the tissue phospholipids from fish fed La had increased levels of 18:2n-6, 20:2n-6 and 20:3n-6, the levels of AA, 22:4n-6 and 22:5n-6 were similar to or significantly reduced compared to fish fed FO. Membrane phospholipids from fish fed LO also had increased 18:3n-3 and 20:4n-3 compared to both other treatments while in some tissues and phospholipid classes EPA was increased compared to fish fed FO. 5. These dietary induced changes in phospholipid eicosanoid precursor ratio were reflected in altered eicosanoid production. In gill cells, stimulated with the calcium ionophore A23187, 12-hydroxy-8, 10, 14, 17-eicosapentaenoic acid (12-HEPE) was the major 12-lipoxygenase product in fish fed Fa. In stimulated gill cells from fish fed SO and LO, 12-HEPE, 12-hydroxy-5, 8, 10, 14-eicosatetraenoic acid (12-HETE), 14- hydroxy-4, 7, 10, 13, 16, 19-docosahexaenoic acid (14-HDHE) and thromboxane B2 (TXB2) were all decreased compared to fish fed FO. However, the ratio of 12- HETE/12-HEPE was significantly elevated in stimulated gill cells from SO-fed fish compared to both other treatments. In stimulated blood leucocytes leukotriene B4 (LTB4)' 12-HETE and TXB2 were significantly increased while LTB5 and 12-HEPE were significantly decreased in fish fed SO compared to those fed FO. Blood leucocytes from fish fed LO produced less TXB2 compared to fish fed SO and prostaglandin E2 was reduced compared to both other treatments. In isolated cardiac myocytes stimulated with A23187, TXB2 production was increased in SO fed fish compared to those fed FO. 6. The activity of cardiac sarcoplasmic reticulum Ca2+-Mg2+ATPase was not affected by dietary treatment. 7. An established cell line derived from chum salmon heart (CHH-1) was utilised to study PUFA metabolism. The CHH-1 cells exhibited considerable A6 desaturase activity but showed no preference towards n-3 over n-6 PUFA. CHH-1 cells did exhibit significant A5 desaturase activity which showed a preference towards n-3 PUFA. No A4 desaturation activity was observed. Elongation of C20 PUFA was especially active in CHH-1 cells with C22 PUFA being specifically incorporated into phosphatidylethanolamine (PE) and phosphatidylserine (PS). CHH-1 cells supplemented with 20:3n-6 showed reduced growth rate, cell death and unusual pycnotic appearance, compared to those supplemented with other PUFA. 8. The lipid compositions of hearts and livers from wild and farmed parr and presmolts were analysed and compared. The fatty acid compositions of triacylglycerols (TAG) and phospholipids from both farmed parr and pre-smolts contained greater amounts of monoenoic fatty acids compared to their wild counterparts. TAG, phosphatidylcholine (PC) and PE from heart and liver of wild fish contained more 18:2n-6 and AA compared to farmed fish. Linolenic acid, EPA and 22:Sn-3 were increased in hearts and livers of wild fish compared to farmed. Docosahexaenoic acid (DHA; 22:6n-3) levels were higher in heart and liver of farmed fish, particularly in heart PC, PS and TAG. The n-3/n-6 PUFA ratio was generally lower in wild compared to farmed fish, largely due to higher n-6 PUFA, in particular AA, in wild fish. 9. The results are discussed with respect to the competitive interactions between PUFA of the n-6 and n-3 series which determine the fatty acid compositions of membrane phospholipids in salmon. The ratio of n-3/n-6 PUFA in membrane phospholipids, and in particular the ratio of AAIEPA, appears important in terms of membrane physiology and biochemistry, eicosanoid production and the development of cardiac histopathological lesions.
30
Teran-Garcia, Margarita de Lourdes. "Functional mapping and characterization of the responsive region required for polyunsaturated fatty acid regulation in the rat fatty acid synthase gene." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3035987.
Full text
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Abad, Sánchez Sergi. "Biotechnological production of polyunsaturated fatty acids omega-3 by heterotrophic microalgae." Doctoral thesis, Universitat Ramon Llull, 2017. http://hdl.handle.net/10803/400556.
Full textAbstract:
La tesi descriu el desenvolupament d’un procés biotecnològic per a l’obtenció d’àcids grassos poliinsaturats (PUFA) omega-3 mitjançant microalgues heterotròfiques. El microorganisme seleccionat és l’Aurantiochytrium limacinum SR21 degut a la seva capacitat per produir PUFA, créixer utilitzant fonts de carboni de rebuig i tolerar medis amb elevades salinitats. Durant la investigació descrita en aquesta tesi, diversos mètodes analítics han estat desenvolupats per tal de monitoritzar el creixement d’ A. limacinum. Diferents eines de disseny d’experiències i modelatge com les matrius ortogonals de Taguchi, les Xarxes neuronals artificials i les superfícies de resposta, han estat utilitzades per desenvolupar el medi de cultiu específicament per A. limacinum. En lloc d’utilitzar les fonts de carboni tradicionals, el procés biotecnològic ha estat desenvolupat utilitzant un subproducte industrial com és el glicerol cru.
Les mateixes eines de disseny i modelització han estat utilitzades per determinar les millors condicions d’aeració i agitació per a estimular la producció d’àcid Docosahexaenoic (DHA). S’han estudiat diferents estratègies de cultiu com el batch, fed-batch, continuous and “multi-stage” continuous reactor per determinar quina ofereix una millor productivitat de DHA. Els cultius operats en batch i fed-batch han generat el major rendiment de DHA (g DHA/ g biomassa). Contràriament, els reactors continus han ofert majors productivitats de DHA DHA (g DHA/l·h), especialment els “multi-stage”. Utilitzant l’estratègia “multi-stage”, el primer bioreactor es programa per estimular la producció de biomassa mentre que els següents bioreactors s’orienten a la producció de DHA.
El productes de DHA que es comercialitzen actualment, estan formulats com a esters metílics o triglicèrids re-esterificats, però en cap cas com a triglicèrids naturals extrets sense modificar. En aquesta tesis es presenta una proposta de purificació per cromatografia (a escala industrial i de laboratori) per tal d’obtenir triglicèrids naturals amb cadenes de DHA.La tesis describe el desarrollo de un proceso biotecnológico para la obtención de ácidos grasos poliinsaturados (PUFA) omega-3 mediante microalgas heterotróficas. El microorganismo seleccionado es Aurantiochytrium limacinum SR21 debido a su capacidad para producir diferentes PUFA, crecer utilizando subproductos Industriales y su tolerancia a elevadas salinidades. Durante la investigación descrita en esta tesis, diferentes métodos analíticos fueron desarrollados para monitorizar el crecimiento de A. limacinum. Diferentes herramientas de diseño de experiencias y modelización tales como, matrices ortogonales de Taguchi, redes neuronales artificiales o superficies de respuesta, han sido utilizadas para desarrollar el medio de cultivo específico para A. limacinum. En lugar de utilizar fuentes de carbono tradicionales, el proceso biotecnológico se ha desarrollado utilizando un subproducto industrial como el glicerol crudo. Las mismas herramientas de diseño y modelización han sido utilizadas para determinar las mejores condiciones de aireación y agitación para estimular la producción de ácido docosahexaenoico (DHA). Se han estudiado diferentes estrategias de cultivo como el batch, fed-batch, continuo y “multi-stage” continuo para determinar cual ofrece mayores productividades de DHA. Los cultivos operados en batch y fed-batch han ofrecido mejores rendimientos de DHA (g DHA/ g biomasa). Sin embargo, los cultivos operados en continuo han ofrecido una mayor productividad de DHA (g DHA/l·h). Utilizando la estrategia de cultivo continuo “multi-stage”, el primer biorreactor se orienta a la producción de biomasa y los siguientes biorreactores se programan para la estimulación de producción de DHA. Los productos de DHA que se comercializan actualmente, se formulan como esteres metílicos o triglicéridos re-esterificados, pero en ningún caso como triglicéridos naturales sin modificar. En esta tesis se presenta una propuesta de purificación por cromatografía (a escala industrial i de laboratorio) para obtener triglicéridos naturales con cadenas de DHA.
This dissertation describes the development of a biotechnological process to obtain polyunsaturated fatty acids (PUFA) omega-3 by heterotrophic microalgae. The selected heterotrophic microorganism was Aurantiochytrium limacinum SR21 due to its capacity to produce PUFA, grow with different carbon sources and tolerate high salinity. During the thesis investigation, diverse analytical methods have been developed in order to monitor A. limacinum growth. Moreover, different experimental design strategies/tools, such us Taguchi orthogonal matrices, Artificial neural network, Response surface methodology, etc. have been used to develop a growth medium specifically optimized for A. limacinum. Instead of using traditional carbon sources, the process has been developed to grow A. limacinum with crude glycerol, an industrial by‐product. The same experimental design tools served to find the best oxygen supply conditions to stimulate either biomass or DHA production. Batch, fed‐batch, continuous and multi‐stage continuous bioreactors have been studied to find the most prolific strategy. Batch and fed‐batch reactor generated the highest DHA yields (g DHA /g biomass). However, continuous cultivations produced higher DHA productivity values DHA (g DHA/l·h), especially the multi‐stage strategy. In a multi‐stage, continuous bioreactor, the first tank/s were dedicated to biomass production whereas the following tanks were set to stimulate DHA production. DHA products currently in market are formulated as DHA methyl esters or re‐esterified triglycerides, but not as unmodified triglycerides. In this thesis, an approach for preparative and process scale chromatography purification of unmodified triglycerides containing DHA has been developed.
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Costabile, Maurizio. "Regulation of T lymphocyte functions by novel engineered polyunsaturated fatty acids." Title page, contents and summary only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09phc8379.pdf.
Full textAbstract:
Bibliography: leaves 254-286. Natural polyunsaturated fatty acids (PUFA) were synthesized and assessed as potential anti-inflammatory agents. ℓ-oxa, ℓ-thia and ¿-thia were found to inhibit T lymphocyte responses in vitro, assessed as lymphoproliferation as well as production of tumour necrosis factor-ℓ (TNFℓ), interferon-¿ and interlukin-2 (IL-2). Three of these compounds were studied in detail and found to be more active than the inhibition seen with fish oil fatty acid 22:6n-3. These compounds, unlike 22:6n-3, were poor stimulators of the human neutrophil respiratory burst, an additional advantage in their use as ant-inflammatory agents.
33
Hussein, Nahed Mohamed. "Nutritional studies of long chain conversion of dietary polyunsaturated fatty acids." Thesis, University of Surrey, 2003. http://epubs.surrey.ac.uk/844191/.
Full textAbstract:
Growing evidence suggests that dietary n-3 very long chain polyunsaturated fatty acids (eicosapentaenoic acid; EPA and docosahexaenoic acid; DHA) reduce the risk of coronary heart disease and stroke, alpha-linolenic acid (alpha-LNA) is the natural precursor of EPA and DHA and is an abundant and accessible source of dietary n-3 PUFA that can be further elongated and unsaturated in vivo. The overall aim of the project is to examine the conversion of alpha-LNA to its long chain metabolite, most importantly DHA. This aim was accomplished by a combination of a human dietary intervention study to assess accumulation of EPA and DHA from dietary alpha-LNA, and 13C-tracer studies of alpha-LNA & linoleic acid (LA) conversion to their long-chain metabolites. The dietary intervention trial was a 12-week parallel design in men expressing an atherogenic lipoprotein phenotype, a common source of lipid-mediated coronary heart disease risk. Diets were enriched with 18 g of alpha-LNA as flaxseed oil (n=21), with a high LA oil (n=17), or with fish-oil (6g/d n=19) as a positive control group. Thus the intention was to provide an increased intake of alpha-LNA with a low ratio of n-6 to n-3 PUFA (1:1 or less), minimizing competition between alpha-LNA and the abundant LA and, in theory, increasing the conversion of alpha-LNA to LC n-3 PUFA. The results from the dietary intervention indicate that, dietary alpha-LNA as flaxseed oil can increase n-3 membrane fatty acid contents, through a 3-fold increase in alpha-LNA (p <0.001)) and 2.5 fold increase in EPA (p<0.001) at week-12, decreasing in n-6:n-3 ratio (p =0.001), but not changing DHA level. In contrast the fish oil diet increased both EPA and DHA. Dietary alpha-LNA had 7% of the efficacy of preformed EPA from fish oil to increase membrane EPA levels. Subjects on the 13C tracer study were a sub-group of the intervention study, studied after 12-weeks on the high alpha-LNA (n=6) or high n-6 (n=5) diets. Subjects were given an oral mixture of 400 mg each of uniformly 13C labelled alpha-LNA and LA in a milk shake after an overnight fast. 13C enrichment was measured in fatty acids isolated from plasma at 1,2,3,7,10 and 14 days after the dose. Of the dose appearing in the plasma 35-45% was converted to EPA with no dietary effects. Some conversion to DHA did occur especially in the high n-6 group (3.9% of dose) compared with the flaxseed-oil group (mean value 0.8% of the dose; p < 0.05). In the single subject studied on the fish-oil diet there was a much lower conversion rate compared to the flaxseed-oil diet. The variability between subjects for percent conversion to DHA ranged from zero to 6.2% of the dose appearing in plasma. Taken together these results clearly establish the effectiveness of dietary alpha-LNA as a method of increasing the concentration of EPA, but not DHA, in membrane phospholipids, with up to 7% of the efficacy of preformed EPA. The increase in the EPA: AA ratio (eicosapentanoic: arachidonic acid) in membrane phospholipids with dietary alpha-LNA is likely to reduce the overall inflammatory environment with beneficial effects for long-term health.
34
Suito, Takuto. "Studies on the roles of polyunsaturated fatty acids for thermal adaptation." Kyoto University, 2019. http://hdl.handle.net/2433/242532.
Full textAbstract:
付記する学位プログラム名: 充実した健康長寿社会を築く総合医療開発リーダー育成プログラムKyoto University (京都大学)
0048
新制・課程博士
博士(工学)
甲第21794号
工博第4611号
新制||工||1718(附属図書館)
京都大学大学院工学研究科合成・生物化学専攻
(主査)教授 梅田 眞郷, 教授 跡見 晴幸, 教授 秋吉 一成
学位規則第4条第1項該当
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Kohan, Alison Bloom. "Mechanism by which dietary polyunsaturated fat regulates lipogenic gene expression." Morgantown, W. Va. : [West Virginia University Libraries], 2009. http://hdl.handle.net/10450/10605.
Full textAbstract:
Thesis (Ph. D.)--West Virginia University, 2009.Title from document title page. Document formatted into pages; contains viii, 141 p. : ill. (some col.). Includes abstract. Includes bibliographical references.
36
Newman, Ronald Edward. "Modulation of avian metabolism by dietary fatty acids." Thesis, The University of Sydney, 2000. http://hdl.handle.net/2123/799.
Full textAbstract:
The role of dietary fatty acids and their subsequent effects on metabolism has received considerable attention in mammalian species. It is becoming increasingly clear that fatty acids have metabolic roles over and above their influence on energy density of the diet. Recent studies have linked changes in the fatty acyl composition of the plasma membrane, induced by the dietary fat profile, to alterations in both lipid and glucose metabolism. These dietary induced changes have profound effects on insulin action, glucose transport and enzyme activity that regulate triglyceride and fatty acid synthesis, factors that ultimately influence protein and lipid deposition of animals. Because of their high growth rate, broiler chickens have a high requirement for energy and the use of triglycerides as a major energy source has resulted in a fat carcass. A change in the glucose-insulin balance has been suggested as being the main reason for differences in adiposity between broilers selected for fatness or leanness. The hypotheses of this thesis is based on the finding that dietary polyunsaturated fatty acids (PUFA's) increase the sensitivity of muscle tissue to insulin and this would presumably augment insulin-stimulated glucose uptake into muscle cells. Therefore, increasing the capacity of broiler muscle tissue to utilise glucose as its principal energy substrate would reduce the bird's reliance on triglycerides and this inturn would result in a leaner carcass. The aims of this study are firstly to explore the role that dietary PUFA's from the n-3 and n-6 series have on the growth and body composition of broiler chickens and secondly to determine the relationships between dietary fatty acid profile, tissue insulin sensitivity and lipid deposition. Because dietary fatty acids have been implicated in the modulation of hormones important for the growth and development of animals, a third aim of this thesis is to determine the effects of dietary n-3 and n-6 polyunsaturated fatty acids on pituitary and adrenal sensitivity. Since the modulation of metabolism by dietary fatty acids has been attributed to changes in the fatty acyl composition of the plasma membrane, the final aim of this study will be to investigate and characterise the molecular species of the breast muscle choline and ethanolamine phospholipids. Feeding either fish oil a source of n-3 PUFA's or sunflower oil a source of n-6 PUFA's fatty acids to broiler chickens resulted in a significant (P<0.01) reduction in the abdominal fat pad mass and a modest increase in breast muscle mass when compared to broilers fed edible tallow. Associated with the changes in carcass composition was an alteration in energy substrate utilisation. This was reflected by lower respiratory quotients and reduced triglyceride and insulin concentrations for the chickens fed the two PUFA diets. Coupled to the shift in energy metabolism was a significant (P<0.05) increase in the proportion of PUFA's incorporated into the abdominal fat pad and breast muscle. The dietary fat supplements resulted in the incorporation of specific fatty acid subtypes. Feeding fish oil significantly increased the proportion of long-chain n-3 PUFA's whereas feeding sunflower oil significantly increased the proportion of long-chain n-6 PUFA's compared to tallow feeding whose tissues were dominated by a higher proportion of saturated fatty acids. It was further shown that dietary n-3 and n-6 PUFA's enhanced glucose /insulin action. Feeding either fish oil or sunflower oil to broiler chickens increased insulin action when examined by an intravenous glucose tolerance test. The maximal insulin release in response to the glucose infusion was higher in the tallow fed group compared to either the sunflower oil or fish oil groups. To estimate the disappearance rate of glucose from the plasma and its incorporation into tissues, 2-deoxy-D-3H glucose was infused into each chicken. There were no significant differences in the clearance rate of 2-deoxy-D-3H glucose from the plasma. However, when measured under steady state conditions, the labelled glucose incorporation into the breast muscle was greater in birds fed fish oil compared to either tallow or sunflower oil feeding. The dietary fatty acid induced increase in insulin action suggests that the sensitivity of muscle cells to insulin was enhanced. This modulation of tissue sensitivity by dietary fatty acids was also shown to occur at the level of the pituitary. To provide an estimate of pituitary sensitivity, bolus GnRH and GHRH infusions were given on different days to chickens fed the three dietary treatments. Feeding sunflower oil (n-6 PUFA's) increased the level of GH that was released in response to the GHRH infusion when compared to birds fed either tallow or fish oil (n-3 PUFA's). This dietary fatty acid modulation appears to be specific to certain pituitary cell types as there was no effect on LH secretion following the GnRH infusion. Dietary fatty acid modulation of endocrine gland sensitivity is particular to the gland type. Although the dietary treatments mediated a distinct pattern in pituitary sensitivity to GHRH infusion, these same three diets did not influence adrenal sensitivity, as there was no difference in the corticosterone profile following either ACTH or CRF infusion. The previously observed physiological changes for the three dietary groups was expected to be positively correlated to an alteration of the plasma membrane phospholipids induced by the dietary fatty acids. Supplementation with fish oil (n-3 PUFA's) significantly increased levels of both eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) into the choline (PC) and ethanolamine (PE) breast muscle phospholipids compared to either sunflower oil (n-6 PUFA's) or tallow supplementation. The increase in n-3 PUFA incorporation was associated with a corresponding decrease in the proportion of arachidonic acid (AA; 20:4n-6) an event that would presumably alter substrate availability for the 1- and 2-series eicosanoids. However, feeding sunflower oil or tallow gave a molecular species profile that was remarkably similar in both fatty acid subtype and proportion. This suggests that the plasma membrane dynamics would be similar for these two dietary groups. Therefore, it is appears that factors other than a change in the fatty acyl- composition of the plasma membrane may be responsible for modifying the physiology of the broiler.
37
Newman, Ronald Edward. "Modulation of avian metabolism by dietary fatty acids." University of Sydney. Veterinary Science, 2000. http://hdl.handle.net/2123/799.
Full textAbstract:
The role of dietary fatty acids and their subsequent effects on metabolism has received considerable attention in mammalian species. It is becoming increasingly clear that fatty acids have metabolic roles over and above their influence on energy density of the diet. Recent studies have linked changes in the fatty acyl composition of the plasma membrane, induced by the dietary fat profile, to alterations in both lipid and glucose metabolism. These dietary induced changes have profound effects on insulin action, glucose transport and enzyme activity that regulate triglyceride and fatty acid synthesis, factors that ultimately influence protein and lipid deposition of animals. Because of their high growth rate, broiler chickens have a high requirement for energy and the use of triglycerides as a major energy source has resulted in a fat carcass. A change in the glucose-insulin balance has been suggested as being the main reason for differences in adiposity between broilers selected for fatness or leanness. The hypotheses of this thesis is based on the finding that dietary polyunsaturated fatty acids (PUFA�s) increase the sensitivity of muscle tissue to insulin and this would presumably augment insulin-stimulated glucose uptake into muscle cells. Therefore, increasing the capacity of broiler muscle tissue to utilise glucose as its principal energy substrate would reduce the bird�s reliance on triglycerides and this inturn would result in a leaner carcass. The aims of this study are firstly to explore the role that dietary PUFA�s from the n-3 and n-6 series have on the growth and body composition of broiler chickens and secondly to determine the relationships between dietary fatty acid profile, tissue insulin sensitivity and lipid deposition. Because dietary fatty acids have been implicated in the modulation of hormones important for the growth and development of animals, a third aim of this thesis is to determine the effects of dietary n-3 and n-6 polyunsaturated fatty acids on pituitary and adrenal sensitivity. Since the modulation of metabolism by dietary fatty acids has been attributed to changes in the fatty acyl composition of the plasma membrane, the final aim of this study will be to investigate and characterise the molecular species of the breast muscle choline and ethanolamine phospholipids. Feeding either fish oil a source of n-3 PUFA�s or sunflower oil a source of n-6 PUFA�s fatty acids to broiler chickens resulted in a significant (P<0.01) reduction in the abdominal fat pad mass and a modest increase in breast muscle mass when compared to broilers fed edible tallow. Associated with the changes in carcass composition was an alteration in energy substrate utilisation. This was reflected by lower respiratory quotients and reduced triglyceride and insulin concentrations for the chickens fed the two PUFA diets. Coupled to the shift in energy metabolism was a significant (P<0.05) increase in the proportion of PUFA�s incorporated into the abdominal fat pad and breast muscle. The dietary fat supplements resulted in the incorporation of specific fatty acid subtypes. Feeding fish oil significantly increased the proportion of long-chain n-3 PUFA�s whereas feeding sunflower oil significantly increased the proportion of long-chain n-6 PUFA�s compared to tallow feeding whose tissues were dominated by a higher proportion of saturated fatty acids. It was further shown that dietary n-3 and n-6 PUFA�s enhanced glucose /insulin action. Feeding either fish oil or sunflower oil to broiler chickens increased insulin action when examined by an intravenous glucose tolerance test. The maximal insulin release in response to the glucose infusion was higher in the tallow fed group compared to either the sunflower oil or fish oil groups. To estimate the disappearance rate of glucose from the plasma and its incorporation into tissues, 2-deoxy-D-3H glucose was infused into each chicken. There were no significant differences in the clearance rate of 2-deoxy-D-3H glucose from the plasma. However, when measured under steady state conditions, the labelled glucose incorporation into the breast muscle was greater in birds fed fish oil compared to either tallow or sunflower oil feeding. The dietary fatty acid induced increase in insulin action suggests that the sensitivity of muscle cells to insulin was enhanced. This modulation of tissue sensitivity by dietary fatty acids was also shown to occur at the level of the pituitary. To provide an estimate of pituitary sensitivity, bolus GnRH and GHRH infusions were given on different days to chickens fed the three dietary treatments. Feeding sunflower oil (n-6 PUFA�s) increased the level of GH that was released in response to the GHRH infusion when compared to birds fed either tallow or fish oil (n-3 PUFA�s). This dietary fatty acid modulation appears to be specific to certain pituitary cell types as there was no effect on LH secretion following the GnRH infusion. Dietary fatty acid modulation of endocrine gland sensitivity is particular to the gland type. Although the dietary treatments mediated a distinct pattern in pituitary sensitivity to GHRH infusion, these same three diets did not influence adrenal sensitivity, as there was no difference in the corticosterone profile following either ACTH or CRF infusion. The previously observed physiological changes for the three dietary groups was expected to be positively correlated to an alteration of the plasma membrane phospholipids induced by the dietary fatty acids. Supplementation with fish oil (n-3 PUFA�s) significantly increased levels of both eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) into the choline (PC) and ethanolamine (PE) breast muscle phospholipids compared to either sunflower oil (n-6 PUFA�s) or tallow supplementation. The increase in n-3 PUFA incorporation was associated with a corresponding decrease in the proportion of arachidonic acid (AA; 20:4n-6) an event that would presumably alter substrate availability for the 1- and 2-series eicosanoids. However, feeding sunflower oil or tallow gave a molecular species profile that was remarkably similar in both fatty acid subtype and proportion. This suggests that the plasma membrane dynamics would be similar for these two dietary groups. Therefore, it is appears that factors other than a change in the fatty acyl- composition of the plasma membrane may be responsible for modifying the physiology of the broiler.
38
Wacker, Alexander, and Eric von Elert. "Polyunsaturated fatty acids : evidence for non-substitutable biochemical resources in Daphnia galeata." Universität Potsdam, 2001. http://opus.kobv.de/ubp/volltexte/2008/1758/.
Full textAbstract:
The factors that determine the efficiency of energy transfer in aquatic food webs have been investigated for many decades. The plant-animal interface is the most variable and least predictable of all levels in the food web. In order to study determinants of food quality in a large lake and to test the recently proposed central importance of the long-chained eicosapentaenoic acid (EPA) at the pelagic producer-grazer interface, we tested the importance of polyunsaturated fatty acids (PUFAs) at the pelagic producerconsumer interface by correlating sestonic food parameters with somatic growth rates of a clone of Daphnia galeata. Daphnia growth rates were obtained from standardized laboratory experiments spanning one season with Daphnia feeding on natural seston from Lake Constance, a large pre-alpine lake. Somatic growth rates were fitted to sestonic parameters by using a saturation function. A moderate amount of variation was explained when the model included the elemental parameters carbon (r2 = 0.6) and nitrogen (r2 = 0.71). A tighter fit was obtained when sestonic phosphorus was incorporated (r2 = 0.86). The nonlinear regression with EPA was relatively weak (r2 = 0.77), whereas the highest degree of variance was explained by three C18-PUFAs. The best (r2 = 0.95), and only significant, correlation of Daphnia's growth was found with the C18-PUFA α-linolenic acid (α-LA; C18:3n-3). This correlation was weakest in late August when C:P values increased to 300, suggesting that mineral and PUFA-limitation of Daphnia's growth changed seasonally. Sestonic phosphorus and some PUFAs showed not only tight correlations with growth, but also with sestonic α-LA content. We computed Monte Carlo simulations to test whether the observed effects of α-LA on growth could be accounted for by EPA, phosphorus, or one of the two C18-PUFAs, stearidonic acid (C18:4n-3) and linoleic acid (C18:2n-6). With >99 % probability, the correlation of growth with α-LA could not be explained by any of these parameters. In order to test for EPA limitation of Daphnia's growth, in parallel with experiments on pure seston, growth was determined on seston supplemented with chemostat-grown, P-limited Stephanodiscus hantzschii, which is rich in EPA. Although supplementation increased the EPA content 80-800x, no significant changes in the nonlinear regression of the growth rates with α-LA were found, indicating that growth of Daphnia on pure seston was not EPA limited. This indicates that the two fatty acids, EPA and α-LA, were not mutually substitutable biochemical resources and points to different physiological functions of these two PUFAs. These results support the PUFA-limitation hypothesis for sestonic C:P < 300 but are contrary to the hypothesis of a general importance of EPA, since no evidence for EPA limitation was found. It is suggested that the resource ratios of EPA and α-LA rather than the absolute concentrations determine which of the two resources is limiting growth.
39
Hartweg, Janine. "Omega-3 polyunsaturated fatty acids on cardiovascular disease in type 2 diabetes." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.504428.
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Bowles, Robert David. "Production of n-3 polyunsaturated fatty acids by thraustochytrids : physiology and optimisation." Thesis, University of Portsmouth, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368473.
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Brady, Louise. "Dietary polyunsaturated fatty acids and the metabolic syndrome in UK Indian Asians." Thesis, University of Reading, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288742.
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Vaezi, Royah. "Enhancing the production of omega-3 polyunsaturated fatty acids in marine diatoms." Thesis, University of East Anglia, 2015. https://ueaeprints.uea.ac.uk/53379/.
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The primary producers of essential omega-3 polyunsaturated fatty acids are marine microalgae, which form the base of the aquatic food web. One alternative source of our ever diminishing stocks of fish and fish oil is via the cultivation of these microorganisms. Unfortunately, these microalgae, of which diatoms are the dominant class, only accumulate oil during specific stages of their life-cycle and/or under nutritional states which are incompatible with the required high density of growth and target fatty acid profile. Additionally, the endogenous levels of desirable fatty acids such as eicospantaenoic acid (EPA; 20:5, n-3) and docosahexaenoic acid (DHA; 22:6, n-3) are usually relatively modest (in the range of 10-35% of total fatty acids) and therefore present an opportunity for enhancement. A database search carried out on the genomes of omega-3-producing unicellular photoautotrophic green alga Ostreococcus sp. RCC809 and cold-water diatom Fragilariopsis cylindrus led to the identification of four novel genes involved in omega-3 biosynthesis. These genes encoded an omega-3-specific Δ6-desaturase, a Δ4-desaturase, a Δ6-elongase and a Δ5- elongase. Overexpression of genes encoding Δ6-desaturase and Δ6-elongase activities in Thalassiosira pseudonana impacted the fatty acid and acyl-CoA profiles of this model centric diatom. Changes to chloroplast and lipid droplet phenotype were also observed. Targeted knock-down of native genes involved in the omega-3 biosynthetic pathway was carried out in T. pseudonana to further understand endogenous omega-3 fatty acid production. Cells targeted for the knock-down of Δ9-desaturase exhibited a drastically altered growth phenotype, but maintained a wild type-like fatty acid profile. This phenotype was attributed to the possibility of another, functionally redundant, protein that escaped sequence-based silencing, masking the knock-down of Δ9-desaturase. The results and observations provided in this thesis contribute new valuable information to the field of lipidomic research in microalgae, breaking new ground in metabolic engineering of lipid metabolism in diatoms.
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Ribeiro, Sónia Augusta Oliveira. "Influence of polyunsaturated fatty acids on multiple sclerosis and use for treatment." Bachelor's thesis, [s.n.], 2021. http://hdl.handle.net/10284/10794.
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Trabalho Complementar apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de licenciada em Ciências da NutriçãoMuitos dos pacientes com esclerose múltipla usam terapias complementares alternativas como parte do tratamento e dos seus sintomas, entre estas a suplementação com ácidos gordos polinsaturados que é a mais comummente utilizada. O interesse no uso de ácidos gordos polinsaturados em pacientes com esclerose múltipla tem vindo a aumentar. O objetivo desta revisão foi perceber de que forma estes ácidos gordos podem influenciar a esclerose múltipla e qual a sua utilidade para o tratamento da mesma. Para a elaboração desta revisão foram realizadas duas pesquisas na PubMed usando as expressões de pesquisa “("polyunsaturated fatty acids") AND multiple sclerosis” e “[(("fatty acids" OR polyunsaturated OR unsaturated) AND multiple sclerosis AND (trial OR cohort OR prospective study)) NOT review]”. Foram incluídos ensaios clínicos, estudos realizados em animais e estudos de coorte, resultando num total de trinta artigos. Os resultados mais promissores sugerindo um efeito benéfico dos ácidos gordos polinsaturados na esclerose múltipla são os provenientes dos estudos realizados em animais, mas estes não podem ser diretamente extrapolados para os humanos. A maioria dos ensaios clínicos analisados, bem como os estudos de coorte, sugerem potenciais benefícios do uso destes ácidos gordos na esclerose múltipla, mas as intervenções usadas incluíram também outras substâncias, recomendações alimentares ou tratamentos farmacológicos. Esta revisão conclui que os ácidos gordos polinsaturados podem ter um impacto positivo na esclerose múltipla quando combinados com outras substâncias, dietas especiais ou tratamentos farmacológicos. No entanto, são necessários mais estudos para determinar o papel efetivo e exclusivo destes ácidos gordos na esclerose múltipla.
Many patients with multiple sclerosis use complementary alternative therapies as part of the treatment and its symptoms, being the polyunsaturated fatty acids' supplementation among the most commonly used. In fact, there is a growing interest on the use of polyunsaturated fatty acids by multiple sclerosis patients. This review therefore aims to understand how these fatty acids can influence multiple sclerosis and their utility in the treatment. To conduct this review two researches on PubMed were made using the search expressions “("polyunsaturated fatty acids") AND multiple sclerosis” and “[(("fatty acids" OR polyunsaturated OR unsaturated) AND multiple sclerosis AND (trial OR cohort OR prospective study)) NOT review]”. Clinical trials, studies conducted in animals and cohort studies were included resulting in a total of thirty articles. The most promising results suggesting a beneficial effect of polyunsaturated fatty acids on multiple sclerosis come from studies conducted in animals, but the results cannot be directly extrapolated to humans. Most of the reviewed clinical trials as well as the cohort studies suggest potential benefits from the use of these fatty acids in multiple sclerosis but the interventions used also included other substances, dietary recommendations, or pharmacological treatments. This review concludes that polyunsaturated fatty acids can have a positive impact on multiple sclerosis when combined with other substances, special diets or even pharmacological treatments. Nevertheless, more studies are needed to determine the effective and exclusive role of these fatty acids in multiple sclerosis.
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Harden, Charlotte Jane. "n-3 long-chain polyunsaturated fatty acids, appetite control and weight management." Thesis, University of Sheffield, 2012. http://etheses.whiterose.ac.uk/3814/.
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Xu, Tao. "Effect of n-3 and n-6 Polyunsaturated Fatty Acids on Inflammation." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/5615.
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Intake of polyunsaturated fatty acids (PUFA) has changed drastically in the past century in the American diet has received attention due to potential effects on chronic inflammation-related metabolic diseases. In this project, the effects of dietary PUFA content and the n-6 to n-3 ratio on inflammatory responses in the acute and chronic inflammation models were evaluated. The PUFA content was modified on a Western diet background to deliver both n-6 and n-3 intakes at the 10th and 90th percentile of the population in the United States, and models of acute and chronic inflammation were tested in mice model. The experimental PUFA diets had a modest effect on the response to lipopolysaccharide (LPS) in the acute inflammation model. A high n-6 to n-3 ratio promoted lipogenesis. In addition, high n-6 PUFA enhanced the inflammatory responses via the NF-κB pathway. In chronic inflammation model, low-grade inflammatory stress was induced by osmotic mini-pump delivery of LPS. A high n-6 intake increased glucose intolerance. On the other hand, high n-6 intake promotes cholesterol ester accumulation in both acute and chronic inflammation models.
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Blay, Matthew. "Maturation of auditory parameters in the preterm infant with particular reference to diet." Thesis, Brunel University, 2000. http://bura.brunel.ac.uk/handle/2438/6513.
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This study was developed from the original protocol which was to examine the role of long chain polyunsaturated fatty acids (LCPUFA) in the maturation of the auditory system in the preterm infant. The particular dietary components under investigation were arachidonic (AA) and docosahexaneoic( DHA) acids. This study investigates the wider aspects and implications of the preterm birth on the maturation of the preterm auditory system. Testing was performed using Auditory brainstem response (ABR) on preterm infants in Hillingdon Hospital's neonatal intensive care unit (NICU). The recruitment criteria was <32 weeks gestational age (GA) or <1500g. A normative data set was produced using term infants (3742 weeks GA). Tympanometric testing was also introduced to assess middle ear (ME) function in both preterm and term infants. The susceptance and conductance components were recorded at frequencies between 226 and 2000Hz. This testing enabled normative data to be established for multi-component, multi-frequency tympanometric analysis. The effect of the preterm birth on tympanometric data was also examined. A total of 22 preterm infants were recruited onto the study. The maturational characteristics of ABR parameters relating to neural transmission and synaptic efficacy were investigated. The peripheral auditory system (PAS) and the lower brainstem region were found to have maturation in their neural transmission properties. The auditory nerve, however, displays constant neural transmission properties throughout the preterm period. Maturation of the synaptic efficacy (using the rate effect) of the PAS was not identified. However, both auditory nerve and lower brainstem regions display reductions in the rate effect. This was greatest in the auditory nerve. The effect of the preterm birth was assessed. The PAS showed lesser conductive properties for the preterm infant during the term period. This behaviour was confirmed by poor tympanometric data for the preterm infants. The auditory nerve showed the same transmission properties for both term and preterm infants. This indicates that the lack of maturation in this region is replicating the characteristics of the term infant developing in utero. The lower brainstem region would seem to be the most susceptible to delayed development in the preterm infant. The rate effect for the PAS and auditory nerve indicate that the extra-uterine environment has not been detrimental to the maturation of synaptic efficacy as measured by the rate effect. The lower brainstem region rate effect is slightly higher for the preterm infants. This may indicate that this region is the most susceptible to possible synaptic deficiency. There is indication of a gender effect for transmission properties in the preterm infant. This suggests superior properties for females in the central auditory system. It is possible that this also occurs on a synaptic level. Dietary analysis suggested that the preterm infants (on this study) fed formula milk enriched with a LCPUFA composition have comparable auditory function (as measured by ABR) with breastfed infants. It is concluded that breastmilk would be the diet of choice due to the additional medical benefits. Tympanometry was found to be well tolerated in both term and preterm neonate populations. Testing in enclosed style incubators in the NICU was successful. Normative characteristics for multi-component tympanornetry at various frequencies was established. The ear canal acoustic and mechanical properties were identified as a source of variability for tympanogram morphology in the neonate populations. The interaction of the neonate external auditory meatus (EAM) violates assumptions relating to numerical data. A lack of maturation was found for preteen data, there was no evolution to the normative term data over the period studied. The more complex nature of the preterm tympanometric data was still observed during the term period. This indicates that there is a difference between the maturational characteristics of the term infant and those for the preterm infant in the clinical environment. The PAS ABR characteristics were compared with tympanometric data collected from the preterm infants. The lack of maturation in the tympanometric data suggests that the major contribution to the ABR maturation during the preterm period is due to the cochlear transduction and basic synaptic delay components. In addition, that poorer ME function (as displayed in the tympanometric data) contributes to the lesser PAS ABR conductive properties in the preterm population by the term period.
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Metcalf, Robert Glenn. "Strategies for increasing consumption of N-3 polyunsaturated fatty acids and their effects on cardiac arrhythmias in humans." Title page, table of contents and abstract only, 2003. http://web4.library.adelaide.edu.au/theses/09PH/09phm5885.pdf.
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"October 2003" Bibliography: leaves 190-210. Ch. 1. Literature review -- Ch. 2. A practical approach to increasing intakes of n-3 polyunsaturated fatty acids: use of novel foods enriched with n-3 fats -- Ch. 3. Effects of fatty acids on the incidence of arrhythmias in patients with implanted cardioverter-defibrillators (ICDs) -- Ch. 4. A pilot study to investigate the effects of n-3 fatty acids on inducible, sustained ventricular tachycardia in patients undergoing electrophysiology testing -- Ch. 5. Conclusions and future directions.
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Rees, Anne-Marie Psychiatry Faculty of Medicine UNSW. "Omega-3 fatty acids and depression in the perinatal period." Publisher:University of New South Wales. Psychiatry, 2009. http://handle.unsw.edu.au/1959.4/43610.
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Omega-3 fatty acids are increasingly recognised as playing an important role in human brain development and mental health. The polyunsaturated fatty acids (PUFAs) include omega-3 and omega-6 fats which are essential fatty acids (EFAs), consumed via the diet. Omega-3 fatty acids are particularly abundant in fish oils. The omega-3 fatty acids are being focused on for their role in depression, the main types being docosahexaenoic acid (DHA), which is abundant in neural tissue, and also eicosapentaenoic acid (EPA) which is biologically very active. There is an emerging literature in relation to omega-3 fatty acid blood levels in depression and the effects of treatment with omega-3. Strong epidemiological evidence has also been published indicating an association between a population's fish intake and depression rates. A specific research focus on omega-3 as a treatment for depression in the perinatal period is also starting to emerge. The importance of this particular area is enhanced by the knowledge that omega-3 depletion occurs during the perinatal period due to fetal diversion for neurodevelopment. In view of the lay public promotion of omega-3 and its appeal to women as a 'natural therapy', there is a need to scientifically evaluate its effectiveness to treat depression in the perinatal period. It is also important to investigate omega-3 as an alternative to antidepressants given the ongoing uncertainties regarding their safety in pregnancy. In this thesis a literature review presents current research relating to this field. This is followed by a description of the methodology and results for the two trials conducted. The results of the double-blind randomised placebo controlled trial of omega-3 as a treatment for depression in the perinatal period were essentially negative. However this result is limited by the small sample size in the study and therefore it may be unwise to interpret the result as conclusive. The case-control study confirmed the hypothesis that omega-3 levels were more depleted in depressed women compared to non-depressed women. A discussion of the results and trial limitations then follows in the thesis. It is concluded that further larger studies are warranted in this area.
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Hantsoo, Liisa. "Fatty Acid Desaturase (FADS) Genetic Variants and Dietary Polyunsaturated Fatty Acid Intake: Associations with Negative Affect." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1333466271.
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Albright, Mark. "Temperature and Polyunsaturated Fatty Acid’s Effect on Daphnia magna Reproduction." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/etd/3516.
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Organisms adapt to their environments by adjusting their biochemistry and physiology; such adaptation is limited by resource availability and physiological constraints. The freshwater crustacean Daphnia magna inhabits a wide range of environments and must survive and reproduce within a range of temperatures. One limit to low-temperature adaptation is thought to be the availability of unsaturated fatty acids necessary to maintain proper fluidity of cellular membranes. D. magna maintained at 10 ºC on a diet poor in unsaturated fatty acids have been observed to produce clutches that fail to develop. However, this has not been observed on a diet rich in unsaturated fatty acids or at a higher temperature regardless of diet. Clonal variation is commonly seen in D. magna life history traits, including heat tolerance, and was also investigated. D. magna were kept at two temperatures and fed two algal diets that differ in unsaturated fatty acid content. To investigate the role of fatty acid composition on the reproductive success of D. magna, fatty acids were extracted from adults and eggs. Of the twenty-one clones studied, no clonal variation was seen in the ability to produce successful clutches at 10 °C on a diet poor in unsaturated fatty acids. Gas chromatography revealed significant differences in 20-carbon fatty acids and suggest a parent-offspring conflict over a limited resource.