Indiana University-Purdue University Indianapolis (IUPUI) / Cellular membranes contain a staggering diversity of lipids. The lipids are heterogeneously distr ibuted to create regions, or domains, whose physical properties differ from the bulk membrane and play an essential role in modulating the function of resident proteins. Many basic questions pertaining to the formation of these lateral assemblies remain. T his research employs model membranes of well - defined composition to focus on the potential role of polyunsaturated fatty acids (PUFAs) and their interaction with cholesterol (chol) in restructuring the membrane environment. Omega - 3 (n - 3) PUFAs are the main bioactive components of fish oil, whose consumption alleviates a variety of health problems by a molecular mechanism that is unclear. We hypothesize that the incorporation of PUFAs into membrane lipids and the effect they have on molecular organization may be, in part, responsible. Chol is a major constituent in the plasma membrane of mammals. It determines the arrangement and collective properties of neighboring lipids, driving the formation of domains via differential affinity for different lipids . T he m olecular organization of 1 -[ 2 H 31 ]palmitoyl -2- eicosapentaenoylphosphatidylcholine (PEPC - d 31 ) and 1 -[ 2 H 31 ]palmitoyl -2- docosahexaenoylphosphatidylcholine (PDPC -d 31 ) in membran es with sphingomyelin (SM) and chol (1:1:1 mol) was compared by solid - state 2 H NMR spectroscopy. Eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids are the two major n - 3 PUFAs found in fish oil, while PEPC -d 31 and PDPC -d 31 are phospholipids containing the respective PUFAs at the sn - 2 position and a perdeuterated palmitic acid a t the sn - 1 position . Analysis of s pectra recorded as a function of temperature indicate s that in both cases, formation of PUFA - rich (less ordered) and SM - rich (more ordered) domains occurred. A surprisingly substantial proportion of PUFA was found to infil trate the more ordered domain. There was almost twice as much DHA (65%) as EPA (30%) . The implication is that n - 3 PUFA s can incorporate into lipid rafts, which are domains enriched in SM and chol in the plasma membrane, and potentially disrupt the activity of signaling proteins that reside therein. DHA, furthermore, may be the more potent component of fish oil. PUFA - chol interactions were also examined through affinity measurements. A novel method utilizing electron paramagnetic resonance (EPR) was develope d, to monitor the partitioning of a spin - labeled analog of chol , 3β - doxyl - 5α - cholestane (chlstn), between large unilamellar vesicles (LUVs) and met hyl - β - cyclodextrin (mβCD). The EPR spectra for chlstn in the two environments are distinguishable due to the substantial differences in tumbling rates , allowing the population distribution ratio to be determined by spectral simulation. Advantages of this approach include speed of implementation and a vo idance of potential artifact s associated with physical separation of LUV and mβCD . Additionally, in a check of the method, t he relative partition coefficients between lipids measured for the spin label analog agree with values obtained for chol by isothermal titration calorimetry (ITC). Results from LUV with different composition confirmed a hierarchy of decreased sterol affinity for phospholipids with increasing acyl chain unsaturation , PDPC possessing half the affinity of the corresponding monounsaturated phospholipid. Taken together, the results of these studies on model membranes demonstrate the potential for PUFA - driven alteration of the architecture of biomembranes, a mechanism through which human health may be impacted.

Thesis (MSc)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: Introduction: The ability of different polyunsaturated fatty acids (PUFAs), especially n-3 PUFAs, to prevent the development of cancer has been under intense investigation the past three decades. Numerous studies have shown that these fatty acids can kill cancer cells in vitro as well as in vivo whilst normal cells remain unaffected. Unfortunately, the cellular and molecular mechanisms responsible for this phenomenon are still poorly understood. This study investigated the signalling pathways modulated by docosahexaenoic acid (DHA) in an adenocarcinoma cell line, in order to shed some light on these unknown mechanisms. Materials & Methods: NCM460 (normal colon epithelial) and CaCo2 (colon adenocarcinoma) cells were cultured and treated with low doses of palmitic acid (PMA), oleic acid (OA), arachidonic acid (AA), and DHA. The effects of these fatty acids on the proliferation of the cells were measured with the MTT assay. The composition of membrane phospholipids of CaCo2 cells was determined after 48h supplementation with different fatty acids by gas chromatography. Also, CaCo2 cells were treated with DHA (10 μM) only and proteins were harvested at fixed time points ranging from 2 minutes to 48 hours. The protein inhibitors wortmannin (PI3 kinase inhibitor), PD 98059 (MEK inhibitor) and SB 203580 (p38 inhibitor) and also RNA interference (RNAi) of the p38 MAPK protein were used to investigate cross-talk between signalling pathways. ERK, p38 MAP kinase, Akt, and p53 were then analysed by Western blotting using phospho-specific and total antibodies. The cleavage of the apoptotic proteins, caspase-3 and PARP were also analysed. Results and discussion: MTT assays revealed that none of the fatty acids were toxic to normal cells. In addition, DHA was shown to be most effective to kill CaCo2 cells whilst protecting NCM460 cells and a subsequent dose response experiment revealed that lower concentrations are most suitable for this purpose. DHA was also shown to be readily incorporated into phospholipids, along with AA. This is associated with increased membrane fluidity, which could affect the localisation, and downstream effects, of various signalling proteins within the membrane. Western blot analysis revealed a rapid increase in activity in most proteins under investigation, especially ERK and Akt (Ser473). Long-term DHA supplementation suppressed the full activation of Akt. This down regulation of survival signalling could lead to cell death in CaCo2 cells. In addition, it was shown that after 48h, DHA induced the cleavage of caspase-3 and PARP, which is indicative of apoptosis. RNAi experiments suggested a possible role for p38 MAPK in the phosphorylation of p53 at Ser15, a site which is associated with DNA damage. Conclusion: DHA exerts its effects by means of cellular signal transduction pathways, particularly by suppression of the important survival-related kinase, Akt. This could have implications for future therapeutic interventions in cancer patients, as fatty acids are safe to use and do not interfere with the functionality of normal tissue. / AFRIKAANSE OPSOMMING: Inleiding: Die vermoë van verskillende poli-onversadigde vetsure (POVSe), veral n-3 POVSe, om die ontstaan van kanker te voorkom, is intens nagevors die afgelope drie dekades. Menigte studies het aangevoer dat hierdie vetsure kankerselle in vitro asook in vivo kan doodmaak, terwyl normale selle nie daardeur beïnvloed word nie. Ongelukkig word die sellulêre and molekulêre meganismes onderliggend tot hierdie verskynsel nie goed begryp nie. Hierdie studie het verskeie seintransduksie-paaie wat deur dokosaheksaenoësuur (DHS) in ‘n adenokarsinoom sellyn gemoduleer word, ondersoek. Materiale & Metodes: NCM460 (normale kolonepiteel) en CaCo2 (kolon adenokarsinoom) selle is onderhou in ‘n selkultuur-laboratorium en behandel met lae dosisse palmitiensuur (PMS), oleïensuur (OS), aragidoonsuur (AS), en DHS. Die invloed van hierdie vetsure op die proliferasie van die selle is d.m.v. die MTT toets bepaal. The samestelling van membraan-fosfolipiede van CaCo2 selle is na 48h behandeling met die verskillende vetsure bepaal deur middel van gaschromatografie. Die CaCo2 selle is ook met DHA (10 μM) alleenlik behandel en teen vaste tydpunte wat wissel van 2 minute tot 48h, waarna proteïene geëkstraeer is. Die proteïen-inhibitore wortmannin (PI3 kinase inhibitor), PD 98059 (MEK inhibitor), en SB 203580 (p38 inhibitor) asook RNAinterferensie (RNAi) teen die p38 MAPK proteïen is ingespan om oorvleueling tussen seintransduksie–weë te ondersoek. ERK, p38 MAPK, Akt, en p53 is geanaliseer deur middel van die Western–klad metode met fosfo–spesifieke en totale antiliggame. Die kliewing van die apoptotiese proteïene caspase-3 en PARP is ook bepaal. Resultate en bespreking: MTT toetse het ontul dat geen vetsure toksies was vir die normale selle nie. Daar is ook gevind dat DHS die mees effektiewe vetsuur was om CaCo2 selle te dood, terwyl NCM460 selle beskerm word. Gevolglik het ‘n dosis-respons eksperiment getoon dat laer konsentrasies die beste geskik is vir hierdie doel. Daar is ook gevind dat DHA maklik in fosfolipiede geïnkorporeer word, tesame met AS. Dit word geassosieer met verhoogde membraan-vloeibaarheid, wat die ligging, en ook stroom-af werking, van verskeie seintransduksie proteïene in die membraan, kan beïnvloed. Westernklad analises het ‘n vinnige verhoging in die aktiwiteite van die meeste proteïene onder die soeklig, getoon, veral ERK en Akt (Ser473). Langdurige DHS behandeling het die maksimale aktiwiteit van Akt onderdruk. Hierdie afname van oorlewing-gerigte seine kan lei tot seldood in CaCo2 selle. Daar is boonop geving dat DHS die kliewing van caspase-3 en PARP geïnduseer het na 48, wat dui op apoptose. Uit die RNAi eksperiment kon daar ook ‘n moontlike rol vir p38 MAPK in die fosforilering van p53 by Ser15, wat geassosieer word met DNS-skade, getoon word. Gevolgtrekking: DHS beoefen sy effekte deur middel van seintransduksie paaie, veral deur die oorlewing-geassosieerde kinase, Akt, te onderdruk. Dit kan implikasies hê vir toekomende terapeutiese ingrypings in kankerpasiënte, aangesien vetsure veilig is om te gebruik en nie skadelik is vir normale weefsel nie.

Introdução: Mudanças na alimentação e atividade física das populações elevaram a incidência de doenças crônicas não-transmissíveis associadas à adiposidade corporal. Este quadro contribui para mortalidade cardiovascular, motivando iniciativas em saúde pública visando à prevenção. Há evidências de que populações que consomem a dieta mediterrânea apresentam menor mortalidade por todas as causas, inclusive cardiovasculares. Os benefícios desta dieta, rica em fibras, gorduras insaturadas e polifenóis, parecem decorrer da atenuação da inflamação, envolvida na gênese de doenças cardiometabólicas. Objetivo: Este estudo investigou os efeitos da modificação de uma refeição diária, o desjejum, de forma a incluir alimentos mediterrâneos, sobre o metabolismo lipídico, glicídico, inflamação subclínica e expressão de genes inflamatórios. Métodos: Foi um ensaio clínico cruzado com duração total de 10 semanas, incluindo 80 adultos com excesso de peso, não-diabéticos. Os participantes passaram por 2 intervenções de 4 semanas no desjejum, com wash-out de 2 semanas entre elas. Os desjejuns, brasileiro e modificado, foram isocalóricos, diferindo quanto ao conteúdo de fibras e tipos de ácidos graxos. Antes e após cada intervenção foi realizado teste de sobrecarga de gorduras (FTT) com refeição rica em gorduras (saturadas e insaturadas MUFA e PUFA, dependendo da intervenção) e coletas sanguíneas seriadas até 240 minutos para determinação de glicose, insulina, lípides e marcadores inflamatórios. Foram também analisadas as expressões de genes inflamatórios, antes e após cada intervenção. Para comparar as respostas às intervenções foram usados teste t de Student ou os correspondentes não-paramétricos e ANOVA para medidas repetidas. Para as expressões dos genes foi utilizado o método delta ct e a expressão relativa calculada tendo como base valores de jejum e pré-intervenção. Valor de p <0,05 foi considerado significante. Resultados: No Artigo 1 (Modification in a single meal is sufficient to provoke benefits in inflammatory responses of individuals at low-tomoderate cardiometabolic risk), o FTT com desjejum brasileiro comparada ao modificado provocou maiores concentrações de IL-6 e IL-8, e esta resposta se acentuou após intervenção. As concentrações de selectina E, TNF-, IFN-, IL-10 e IL-17 se elevaram apenas após intervenção brasileira. No Artigo 2 (Inflammatory and metabolic response to dietary intervention differs among individuals at distinct cardiometabolic risk levels), a intervenção com desjejum modificado reduziu (p<0.05) a circunferência da cintura e pressão arterial e aumentou as concentrações de HDL. Indivíduos com síndrome metabólica melhoraram fatores clássicos (pressão arterial e glicemia, além de apolipoproteína B) após desjejum modificado, enquanto aqueles sem a síndrome melhoraram marcadores inflamatórios. O Artigo 3 (Comparison of inflammatory genes expression and their circulating products after short-term fatty acids interventions in humans) mostrou que o FTT com desjejum rico em gordura saturada induziu maior expressão pós-prandial de IL-1 quando comparado ao rico em insaturadas, antes e após as intervenções. Houve tendência à maior expressão de IFN- e IL-6 após intervenção com desjejum brasileiro. Na metanálise do Artigo 4 (Impact of the content of fatty acids of oral fat tolerance tests on postprandial triglyceridemia: systematic review and meta-analysis) foram incluídos 18 estudos buscando comparar as respostas dos triglicérides a ácidos graxos saturados e insaturados. Verificou-se que após 8 horas de refeição rica em MUFA há menor trigliceridemia. As menores concentrações observadas após ingestão de PUFA em relação à de saturados não atingiu significância. Conclusões: Pequenas modificações na dieta podem, em período relativamente curto, promover benefícios ao perfil de risco cardiometabólico. Tais benefícios foram evidentes em parâmetros clínicos habituais e reforçados pelos efeitos na expressão de genes inflamatórios e em marcadores circulantes. Vislumbra-se potencial de aceitação da introdução de componentes da dieta mediterrânea em população não-mediterrânea como a brasileira, o que poderia melhorar o perfil de risco cardiometabólico no longo prazo. / Introduction: Changes in dietary pattern and physical activity of populations have elevated the incidence of chronic non-communicable diseases associated with increased adiposity. Evidence has shown that populations consuming Mediterranean diets have lower mortality from all causes, including cardiovascular diseases. The benefits of this diet rich in fiber and unsaturated fats, derived in part on the effects of these nutrients on inflammatory condition that triggers cardiometabolic diseases. Objective: This study investigated the effects of changing a meal of Brazilian menu, the breakfast, in order to approximate it to the Mediterranean pattern on lipid and glucose metabolism, subclinical inflammation and also on the expression of inflammatory genes. Methods: This study was a crossover trial lasting a total of 10 weeks, including 80 overweight adults, nondiabetic without drug treatment for dyslipidemia. Participants who met the inclusion criteria underwent two 4-week interventions in breakfast, with wash-out of two weeks between them. The breakfasts (Brazilian and modified) were isocaloric, differing according to fiber and types of fatty acids contents. Before and after each intervention, fat tolerance tests with meals rich in fat (saturated and unsaturated depending on the intervention) were perfomed, with blood sample collections for glucose, insulin, lipids and inflammatory markers up to 240 minutes. Also, expression of inflammatory genes before and after each intervention was analyzed. To compare the acute and sub-acute responses to interventions were used Student t test or the corresponding nonparametric test and ANOVA for repeated measures. For expression of the genes, delta CT method was used and the relative expression calculated based on fasting and pre-intervention values. P value <0.05 was considered significant. Results: In Article 1 (Modification in a single meal is sufficient to provoke benefits in inflammatory responses of Individuals at low-to-moderate cardiometabolic risk), we observed higher IL-6 and IL- 8 concentrations after ingestion of the Brazilian FTT compared with the modified one, whose elevations were even more pronounced after the intervention period. Higher concentrations of E-selectin, TNF-, IFN-, IL-10 and IL-17 were found at fasting and in postprandial state only after the Brazilian intervention. In Article 2 (Inflammatory and metabolic response to dietary intervention Differs Among Individuals at distinct cardiometabolic risk levels), the intervention with the modified breakfast decreased waist circumference and blood pressure and increased the concentrations HDL (p <0.05). Participants with metabolic syndrome showed improvements in traditional risk factors (blood pressure and plasma glucose and apolipoprotein B) whit the modified breakfast, while those without the syndrome improved inflammatory markers. Article 3 (Comparison of inflammatory gene expression and their circulating products after short-term interventions fatty acids in humans) showed that the Brazilian FTT induced higher expression of IL-1 compared to the modified one, before and after the interventions. A tendency for higher postprandial expression of IFN- and increased IL-6 expression after intervention with Brazilian breakfast were also detected. In the meta-analysis of Article 4 (Impact of the content of fatty acids in oral fat tolerance tests on postprandial triglyceridemia: systematic review and metaanalysis) a total of 18 studies were included. When comparing the triglycerides responses to saturated and unsaturated fatty acids, lower areas under the curve with the meals rich in MUFA were observed. Postprandial triglyceridemia after PUFA was lower, but not significantly different from meals rich in saturated fat. Conclusions: Small changes in diet are able to induce benefits in cardiometabolic risk profile in a relatively short period. Such benefits are seen in routine clinical parameters, which are compatible with the favorable effects on the expression of inflammatory genes and circulating biomarkers. There is a potential acceptance of introducing components of the Mediterranean diet in non-Mediterranean populations like Brazil, which could improve the cardiometabolic risk profile in the long term.

by Kwan Kwok Yiu. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 145-155). / Acknowledgment --- p.i / Abstract --- p.ii / List of Tables --- p.vii / List of Figures --- p.x / List of Abbreviations --- p.xii / Chapter Chapter 1 --- Literature review / Chapter 1.1 --- Historical background --- p.1 / Chapter 1.2 --- Chemistry of trans and cis fatty acids --- p.3 / Chapter 1.3 --- Dietary source of trans fatty acids --- p.6 / Chapter 1.4 --- Consumption of trans fatty acids among Western countries --- p.9 / Chapter 1.5 --- Current health concern for excessive intake of trans fatty acids --- p.10 / Chapter 1.6 --- Metabolism of trans fatty acids --- p.13 / Chapter 1.6.1 --- Absorption --- p.15 / Chapter 1.6.2 --- Oxidation --- p.15 / Chapter 1.6.3 --- Incorporation --- p.16 / Chapter 1.6.4 --- Selectivity --- p.17 / Chapter 1.7 --- Impact of trans fatty acids on essential fatty acid metabolism --- p.19 / Chapter 1.8 --- Desaturation and elongation of trans fatty acids --- p.21 / Chapter 1.9 --- Trans fatty acids and neonatal growth --- p.23 / Chapter Chapter 2 --- Amount of trans fatty acids in Hong Kong fast foods / Chapter 2.1 --- Introduction --- p.25 / Chapter 2.2 --- Objective --- p.25 / Chapter 2.3 --- Materials and methods --- p.26 / Chapter 2.4 --- Results --- p.27 / Chapter 2.5 --- Discussion --- p.31 / Chapter Chapter 3 --- Cross-cultural study of trans fatty acids in human milk / Chapter 3.1 --- Introduction --- p.35 / Chapter 3.2 --- Objective --- p.35 / Chapter 3.3 --- Materials and methods --- p.36 / Chapter 3.4 --- Results / Chapter 3.4.1 --- Dietary information --- p.38 / Chapter 3.4.2 --- Fatty acid composition of Chinese and Canadian human milk --- p.40 / Chapter 3.4.3 --- Difference between Chinese and Canadian human milk --- p.40 / Chapter 3.4.4 --- Difference between Hong Kong and Chongqing Chinese human milk --- p.43 / Chapter 3.4.5 --- The change in milk fat and LCPUFA as lactation progresses --- p.43 / Chapter 3.5 --- Discussion / Chapter 3.5.1 --- Trans fatty acids in human milk --- p.46 / Chapter 3.5.2 --- Content of LCPUFA in human milk --- p.47 / Chapter 3.5.3 --- Content of 18:2n-6 in human milk --- p.48 / Chapter 3.5.4 --- Fat content in Hong Kong and Chongqing Chinese human milk --- p.49 / Chapter 3.6 --- Conclusion --- p.50 / Chapter Chapter 4 --- Trans fatty acids and maternal and neonatal essential fatty acid metabolism / Chapter 4.1 --- Introduction --- p.51 / Chapter 4.2 --- Objectives --- p.53 / Chapter 4.3 --- Materials and methods --- p.53 / Chapter 4.4 --- Results / Chapter 4.4.1 --- Experiment1 / Chapter 4.4.1.1 --- Relationship between the trans fatty acids in maternal diet and those in milk --- p.64 / Chapter 4.4.1.2 --- Relationship between the trans fatty acids in maternal diet and those in neonatal liver --- p.64 / Chapter 4.4.1.3 --- Content of 20:4n-6 in milk and in neonatal liver relative to that in maternal diet --- p.72 / Chapter 4.4.2 --- Experiment2 / Chapter 4.4.2.1 --- Amount of trans fatty acids in rat milk --- p.75 / Chapter 4.4.2.2 --- Trans fatty acids in rat liver phospholipids --- p.75 / Chapter 4.4.2.3 --- Linoleic acid (18:2n-6) content in rat and its relation to maternal diets --- p.86 / Chapter 4.4.2.4 --- Content of 20:4n-6 in rat milk --- p.86 / Chapter 4.4.2.5 --- Content of20:4n-6 in rat liver --- p.89 / Chapter 4.4.2.6 --- Suppression of the synthesis of 20:4t isomers in maternal and neonatal liver --- p.89 / Chapter 4.5 --- Discussion / Chapter 4.5.1 --- Relationship between fatty acid composition of diet and that of milk --- p.93 / Chapter 4.5.2 --- 20:4n-6 in rat milk --- p.95 / Chapter 4.5.3 --- Transfer of trans fatty acids from maternal diet to neonatal liver phospholipids --- p.98 / Chapter 4.5.4 --- The inhibitory effect of trans fatty acids on synthesis of 20:4n-6 in neonatal liver --- p.99 / Chapter 4.5.5 --- Effect of 18:2n-6 supplement on 20:4n-6 level of neonatal liver --- p.101 / Chapter 4.5.6 --- Suppression of 18:2n-6 supplement on synthesis of 20:4t isomers --- p.101 / Chapter 4.6 --- Conclusion --- p.104 / Chapter Chapter 5 --- Accumulation and turnover of trans fatty acids / Chapter 5.1 --- Introduction --- p.105 / Chapter 5.2 --- Objective --- p.105 / Chapter 5.3 --- Materials and methods --- p.106 / Chapter 5.4 --- Results / Chapter 5.4.1 --- Accumulation of trans fatty acids in liver and adipose tissue --- p.108 / Chapter 5.4.2 --- Selectivity of individual 18:2 trans isomersin liver and adipose tissue --- p.112 / Chapter 5.4.3 --- Turnover of trans fatty acids --- p.112 / Chapter 5.4.4 --- Accumulation and turnover of 18:lt in brain --- p.115 / Chapter 5.5 --- Discussion / Chapter 5.5.1 --- Accumulation of trans fatty acids in liver and adipose tissue --- p.120 / Chapter 5.5.2 --- Turnover of trans fatty acids --- p.122 / Chapter 5.5.3 --- Accumulation and turnover of trans fatty acidsin brain --- p.124 / Chapter 5.6 --- Conclusion --- p.125 / Chapter Chapter 6 --- In vivo Oxidation of trans fatty acids in rat / Chapter 6.1 --- Introduction --- p.126 / Chapter 6.2 --- Objective --- p.127 / Chapter 6.3 --- Materials and methods --- p.127 / Chapter 6.4 --- Results --- p.129 / Chapter 6.4.1 --- Apparent oxidation of saturated fatty acids --- p.136 / Chapter 6.4.2 --- Apparent oxidation of 18:lt relative to 18:ln-9 --- p.136 / Chapter 6.4.3 --- Oxidation of 18:2t isomers relative to 18:2n-6 --- p.137 / Chapter 6.4.4 --- Effect of 18:2n-6 supplement in PHCO diet on oxidation per se --- p.137 / Chapter 6.5 --- Discussion --- p.138 / Chapter 6.5.1 --- Oxidation of 18:lt and 18:2t isomers --- p.139 / Chapter 6.5.2 --- Effect of 18:2n-6 supplement on oxidation per se --- p.140 / Chapter 6.6 --- Conclusion --- p.141 / General conclusion --- p.142 / References --- p.145

Stearoyl-CoA desaturase1 (SCD1) catalyzes the synthesis of conjugated linoleic acid (CLA) and mono-unsaturated fatty acids (MUFA) in the mammary gland of ruminant animals. We hypothesized that single nucleotide polymorphisms (SNPs) in the coding region, 5' and 3' untranslted regions (UTRs) of the SCD1 gene would influence the activity of SCD1 enzyme and consequently account for some within-breed variations in milk CLA and MUFA. Sequence analysis of the coding region of the SCD1 gene of Jerseys and Holsteins revealed c.702A&rarr;G, c.762T&rarr;C and c.878C&rarr;T SNPs in exon 5 in both breeds and c.435G&rarr;A in exon 3 in Holsteins. The SNPs resulted in: A (G435A702T 762C878), A1 (A435A702T 762C878), B (G435G702C 762T878) and B1 (A435G702C 762T878) coding variants in Holsteins and only variants A and B in Jerseys. Only SNP 878C&rarr;T resulted in a non-synonymous codon change resulting in p.293Ala and p.293Val protein variants or alleles at the SCD1 locus. Subsequent association studies found significantly higher C10 index, C12 index and C14 index and consequently higher concentrations of C10:1 and C12:1 in p.293AA cows compared to the p.293VV cows in both breeds. The SCD1 genotype had no influence on concentrations of C141, C16:1, C18:1 and CLA in both breeds. / Sequence analysis of the 5' and 3' UTRs revealed no SNPs in the 5'UTR and a total of 14 SNPs in the 3'UTR of both breeds. The SNPs were in complete linkage disequilibrium resulting in 3 haplotypes or regulatory variants: H1 (G1571G1644C1763C2053A2584 A3007C3107G3208 T3290G 3497G3682A4399C4533G4881), H2 (G1571G1644A1763C2053A 2584G3007 C3107G3208T3290G3497G 3682A4399C4533G4881) and H3 (T 1571C1644A1763 T2053G2584G3007T 3107A3208C3290A3497A3682T 4399T4533A4881) in Holsteins and only H1 and H3 variants in Jerseys. A subsequent association study involving 862 Holstein cows, found the H1 regulatory variant to be associated with higher C10 and C12 desaturase indices and consequently with higher concentrations of C10:1 and C12:1 compared with the H3 variant. The effects of the H2 variant were intermediate to those of H1 and H3. 3'UTR genotype had no influence on the concentrations of C14:1, C16:1, C18:1 and CLA. The concentrations of C10:1 and C12:1 in milk fat could therefore be due to effects of SNPs in the open reading frame and the 3'UTR regions of the SCD1 gene. These results indicate that SNPs in the coding and 3'UTR regions of the SCD1 gene could be used as markers for genetic selection for increased C10:1 and C12:1 contents of milk.

No description available.

I. DESCRIPTION DE PROJET DE RECHERCHE<p><p>Le canal sodium épithélial bloquable par l’amiloride (ENaC) est une protéine intégrale de la membrane apicale des épithéliums impliqués dans l’absorption du sodium. Deux fonctions majeures sont directement liées au fonctionnement d’ENaC. D’une part, la régulation de la balance sodée par le rein et donc de la pression artérielle et d’autre part, la clairance du fluide alvéolaire pulmonaire.<p>Le transport vectoriel de sel et d’eau à travers ces épithéliums à jonctions serrées repose sur un transport actif de sodium entraînant un flux osmotique d’eau. Ce transport de sodium s’effectue en deux étapes: l’entrée apicale, par diffusion, facilitée via ENaC, et la sortie basolatérale, active, par les pompes Na+/K+ ATPases.<p><p>Ces dernières années, un intérêt grandissant est porté sur les acides gras polyinsaturés à longues chaînes de type oméga 3 (PUFAs) et leurs implications dans divers processus physiologiques. Entre autres effets, les PUFAs modulent différents types de canaux ioniques (canaux Na+ dépendant du voltage, Ca++ L-type, K+).<p>Les études in vivo impliquant un effet à long terme des PUFAs décrivent des mécanismes inhibiteurs. Cependant, lors d’une étude précédente, axée sur la composition lipidique des membranes de cellules rénales en culture et l’influence de l’ajout d’acides gras saturés et insaturés sur le transport du sodium, nous avons constaté que les acides gras polyinsaturés à longues chaînes de type oméga 3 augmentaient la réabsorption du sodium. Ces résultats pourraient être intéressants, car les canaux sodiques de l’épithélium alvéolaire sont en contact direct avec le surfactant, dont la composition lipidique varie en fonction de l’apport alimentaire en PUFAs. Chez les prématurés humains, le syndrome de détresse respiratoire est une des causes les plus fréquentes de mortalité. Dans un certain nombre de cas, on peut restaurer une fonction pulmonaire satisfaisante par l’administration de surfactant.<p><p>Dans ce travail, nous avons opté pour une approche fondamentale des mécanismes de régulation du canal sodium épithélial par l’acide eicosapentanoïque (EPA, C 20:5, n-3). Des études électrophysiologiques, biochimiques et d’imagerie cellulaire ont été réalisées sur la lignée cellulaire A6 de rein d’amphibien, qui sert d’épithélium modèle pour l’étude d’ENaC depuis plus de 25 ans. Cette lignée exprime des canaux sodiques très sélectifs et possède des propriétés électrophysiologiques facilitant l’étude de leur régulation.<p><p>Ce travail nous a permis de mettre en évidence de nouveaux mécanismes fondamentaux dont la pertinence physiologique et /ou clinique ne pourra être établie qu’en transposant cette étude sur un modèle in vivo, comme nous le proposons dans les perspectives.<p><p>Dans le présent travail, nous avons étudié :<p><p>1.\ / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished

The desire to enhance and make ourselves better is not a new one and it has continued to intrigue throughout the ages. Individuals have continued to seek ways to improve and enhance their well-being for example through nutrition, physical exercise, education and so on. Crucial to this improvement of their well-being is improving their ability to remember. Hence, people interested in improving their well-being, are often interested in memory as well. The rationale being that memory is crucial to our well-being. The desire to improve one’s memory then is almost certainly as old as the desire to improve one’s well-being. Traditionally, people have used different means in an attempt to enhance their memories: for example in learning through storytelling, studying, and apprenticeship. In remembering through practices like mnemonics, repetition, singing, and drumming. In retaining, storing and consolidating memories through nutrition and stimulants like coffee to help keep awake; and by external aids like notepads and computers. In forgetting through rituals and rites. Recent scientific advances in biotechnology, nanotechnology, molecular biology, neuroscience, and information technologies, present a wide variety of technologies to enhance many different aspects of human functioning. Thus, some commentators have identified human enhancement as central and one of the most fascinating subject in bioethics in the last two decades. Within, this period, most of the commentators have addressed the Ethical, Social, Legal and Policy (ESLP) issues in human enhancements as a whole as opposed to specific enhancements. However, this is problematic and recently various commentators have found this to be deficient and called for a contextualized case-by-case analysis to human enhancements for example genetic enhancement, moral enhancement, and in my case memory enhancement (ME). The rationale being that the reasons for accepting/rejecting a particular enhancement vary depending on the enhancement itself. Given this enormous variation, moral and legal generalizations about all enhancement processes and technologies are unwise and they should instead be evaluated individually. Taking this as a point of departure, this research will focus specifically on making a case for ME and in doing so assessing the ESLP implications arising from ME. My analysis will draw on the already existing literature for and against enhancement, especially in part two of this thesis; but it will be novel in providing a much more in-depth analysis of ME. From this perspective, I will contribute to the ME debate through two reviews that address the question how we enhance the memory, and through four original papers discussed in part three of this thesis, where I examine and evaluate critically specific ESLP issues that arise with the use of ME. In the conclusion, I will amalgamate all my contribution to the ME debate and suggest the future direction for the ME debate.