Dissertations / Theses on the topic 'Folic acid in human nutrition'

Maternal folate intake and levels of folate in milk, serum and red cells were assessed in 57 healthy, lactating women, ages 22-38 years, throughout early (0-6 months) and later (7-23 months) lactation. Average maternal folate intake from diet alone was 212 µg/day or 78.5% RDA (1989) and mean total folate intake from diet and supplements was 314% RDA (878 µg/day) at 0-6 months and 238% RDA (620 µg/day) at >6 months. Human milk folate was sufficient to meet the RDA (1989) for infants. Milk folate was not related to maternal folate intake, maternal serum or red cell folate and was unaffected by extended lactation (7-23 months), perhaps at the expense of maternal folate stores. Compared with early lactation, serum folate decreased (p=0.0004) and red cell folate tended to decrease (p=0.08) in later lactation and were both increased by folate supplementation (p < 0.001).Level of folic acid supplementation appeared to predict red cell folate concentration. An average of 884 µg supplemental folate/day was associated with red cell folate levels >400 ng/mL, which have previously been reported as optimal for prevention of folateresponsive neural tube defects. The addition of an 880 µg/day folic acid supplement to the diet of lactating women may raise red cell folate concentrations of lactating women to protective levels.
Department of Family and Consumer Sciences

Thesis (MTech (Food Technology))--Cape Peninsula University of Technology, 2016.
In South Africa malnutrition exists due to inadequate dietary intake of micronutrients which is one of the major causes of vitamin deficiencies leading to disease. The treatment of malnutrition over the past years has been a considerable burden on the South African economy. Therefore, food fortification is one of the current strategies used to minimize malnutrition by increasing the nutritional value of staple foods. Commercial dairy products and pharmaceutical nutritional products (food supplements) in South Africa have been developed and produced for affluent consumers. Hence the need to develop an affordable fortified dairy product for the majority of South Africans prompted this study aimed at using a “naturally” fortified kefir beverage with vitamin B12 and folate to increase B-vitamins levels. Since Propionibacterium freudenreichii and Streptococcus thermophilus are known to be good producers of vitamin B12 and folate, respectively, and propionibacteria has the ability to grow symbiotically in the presence of lactic acid bacteria, the inclusion of these organisms with the kefir grains was an achievable objective. In order to conduct the analysis of vitamin B12 and folate in the samples, sample extraction and HPLC assay techniques were developed. The extraction of vitamin B12 and folate were achieved by using KCN extraction buffer and the trienzymatic method, respectively. The samples were also subjected to purification and concentration using solid phase extraction for optimum results. All standards and samples were flushed with nitrogen gas and stored for a maximum of 2 weeks at –20°C to prevent B-vitamin deterioration. The HPLC assembly for the vitamin B12 analysis included a Luna C18 column and a diode array detector (DAD) for the detection and quantification. For the folate analysis it included a Zorbax SB-C18 and Luna C18 columns in tandem and the fluorescence detector (FLD) was used for the detection and quantification of THF, 5-CH3-THF and 5-CHO-THF, while the DAD was used for PGA and pteroyltri-γ-L-glutamic acid concentration in the samples.

Thesis (M.P.H.)--Georgia State University, 2007.
Title from file title page. Russ Toal, committee chair; Catherine McCarroll, Joseph Mulinare, committee members. Electronic text (83 p. : ill.) : digital, PDF file. Description based on contents viewed Jan 8, 2008. Includes bibliographical references (p. 79-83).

This thesis investigates the use of scientific evidence in the process of making public health policy. A case study located within a food regulation setting is used. The aim is to test theory against this case study. The outcome is a theoretical understanding of the use of scientific evidence in the policy-making process in a food regulation setting. Food regulation can influence food composition and food labelling and thereby affect the population's dietary intake. Frequently there are contested values, beliefs, ideologies and interests among stakeholders regarding the use of food regulation as a policy instrument to effect public health outcomes. The protection of public health and safety, taking into account evidence based practice, is generally employed by food regulators as the priority objective during the policy-making process to adjudicate among the competing expectations of stakeholders. However, this policy objective has not been clearly defined and is vulnerable to interpretation and application. The process by which folate fortification policy was made in Australia, in response to epidemiological evidence of a relationship between folate intake during the periconceptional period and reduced risk of neural tube defects, was analysed as a case study of the policy-making process. The folate fortification policy created a precedent for both food fortification and subsequently health claims policy in Australia. A social constructivist method was used to analyse the case study. The method involved deconstructing the food regulatory system into three levels; decision-making process; procedural; and political environment. Data aligned with each level of analysis was collected from 22 key informant interviews, documentary sources, field notes and surveys of both a random sample of the Australian population's knowledge of folate and use of folic acid-containing supplements (n = 5422), and the implementation of folate fortified food products into stores (n = 60). The insights that emerged from each of the three levels of analysis were assessed iteratively to identify a pattern of interrelationships associated with the policy-making process within the food regulatory system. The identified pattern was interpreted against existing theory to gain a theoretical understanding of the public health policy-making process in this political setting. The central argument of this thesis extends Sabatier and Jenkins-Smith's Advocacy Coalition Framework theory to a food regulation setting. The argument is that within the contemporary political climates of neoliberalism and globalisation, a coalition between corporate interests and the values of scientists with a positivist-reductionist approach to public health research is privileged so as to invoke certain scientific evidence to, in turn, legitimise food regulation policy decisions. The theory will help to inform policy-makers about how and why the public health policy objective in a food regulation setting is interpreted and applied. This will contribute to improving policy practice intended to effect public health outcomes. It is concluded that irrespective of the quantity and quality of the scientific evidence that is being made available, scientific evidence cannot be assumed to speak for itself Policy-making is an inherently political and value-laden process and the potential for politically motivated interpretation and application of otherwise value-neutral scientific evidence can undermine the investment in its generation. From this perspective, evidence based practice, far from liberating policy-making from political influence, can itself become part of the problem rather than the solution. Nevertheless, rational evidence based practice is an ideal to strive for and a series of recommendations is proposed to help make the use of evidence in current food regulation policy processes more transparent and democratic.

4 pp.
Before they may even know they are pregnant; women’s bodies and their level of folate play a critical role in preventing certain birth defects, specifically neural tube defects (NTDs). NTDs are birth defects in the brain, spinal cord, or spine. Considered ‘one of the most important public health discoveries of this century’ is that daily supplemental folic acid taken before becoming pregnant significantly reduces the risk of NTDs (1). In 1998, the United States made sweeping efforts that fortified cereal grains with folic acid to ensure all Americans consume adequate amounts of this vitamin. So what exactly is folate? What are the functions of this vitamin? What foods have high levels of folate and what is the recommended daily intake? This article will answer these questions and will go on to explain folic acid fortification and the impact fortification has had on the incidence of NTDs in Arizona.

Many Mexican women consume inadequate amounts of folic acid. Fortification of the corn tortilla could be an effective way to help increase the folic acid levels among the Mexican population. Previous studies have shown significant folic acid losses in fortified tortilla dough (masa) as it is held before baking. This loss in folic acid could be due to degradation by lactic acid bacteria naturally present in the masa. The microflora of traditionally made nixtamalized corn masa from six tortilla mills in Guadalajara, Mexico were isolated and characterized, and their effect on folic acid content was evaluated. Isolated bacteria were identified using whole cell fatty acid analysis via MIDI Inc.'s Microbial Identification System. Twenty-two unique bacterial species were identified, primarily belonging to the Streptococcus and Lactobacillus genera. Lactic acid bacteria were the predominant microorganisms, with counts ranging from 10^4 to 10^7 cfu/g. Aerobic mesophilic bacteria also ranged from 10^4 to 10^7 cfu/g. Coliforms and yeasts and mold were present at significantly lower levels. Masa samples, prepared from sterile fortified corn masa flour, were inoculated with a cocktail of bacteria isolated from the individual mills. Control samples were prepared using sterile media. Inoculated and uninoculated control samples were held at 56°C for 0, 3 and 6 hours, mimicking the elevated temperature of the masa as it is held before baking. The loss of folic acid in the sterile control was not different from the inoculated samples, indicating that the decline in folic acid is not due to bacteria present in the masa, but appears to be a chemical degradation related to time and temperature.

[EN] The present PhD thesis, entitled "Encapsulation of folic acid in silica porous supports: a nutritional and technological approach", focuses on the development of new smart systems for the controlled delivery of folic acid for nutritional applications. The first part of the thesis shows folic acid encapsulation in polyamines-functionalized silica porous matrices from a nutritional approach. The first part evaluates not only the influence of the loading method and the type of silica support employed (MCM-41, SBA-15, UVM-7 and Hollow Silica) on the efficacy of folic acid encapsulation, but also the influence of the morphology and porous system on the folic acid delivery profile from different supports. Folic acid release studies from different supports with various pH values have demonstrated that the designed systems are capable of smartly modulating the delivery of the folic acid dependent on the pH of the medium (inhibition of the release at an acidic pH -stomach-, controlled release at a neutral pH -intestine-). This capacity makes these developed delivery systems an excellent alternative to direct fortification to successfully modulate the bioaccessibility of folic acid along the gastrointestinal tract. The stability of the supports during an in vitro digestive process was evaluated, and demonstrated that not only small particles can be attacked during the digestion process, but also the functionalization with organic molecules, which act as molecular gates, prevents this attack. Finally, the cell viability studies carried out with four different cell lines revealed that neither the supports nor their degradation products caused any specific toxicity during the in vitro digestive process. The second part evaluates the influence of adding different silica supports to two food matrices: gelatin gels and yoghurts. This technological approach enabled us to know that the capacity of these smart systems to deliver folic acid in a controlled manner during an in vitro digestive process is mantained even after their incorporation in stirred yoghurt. The effect of the matrices on the gel's physical properties depends on the particle size, functionalization and concentration. Finally, this thesis tested that the optimization of folic acid loading, achieved in the first part of the thesis, allowed the fortification of yoghurt with 100% of the recommended daily allowance of folic acid with a very low amount of the system. This fortification affected neither the physico-chemical properties of the yoghurt, nor bacterial viability. In summary, it was concluded that the present thesis globally deals with folic acid encapsulation in silica porous matrices to be used in nutritional and food applications, which include the optimization of loading, release studies at diferent pH, in vitro digestions, stability studies of the employed matrixes, biocompatibility studies, and studies into the influence of their addition to food matrixes. The obtained results positively exhibit that the developed smart folic acid delivery systems open up a new way of fortifying food without endangering the properties of the food to which they are added.
[ES] La presente tesis doctoral que lleva por título "Encapsulación de ácido fólico en soportes porosos de óxido de silicio: una aproximación nutricional y tecnológica" está centrada en el desarrollo de nuevos sistemas inteligentes de liberación controlada de ácido fólico para aplicaciones nutricionales. La primera parte de la tesis muestra la encapsulación de ácido fólico en matrices porosas de óxido de silicio funcionalizadas con poliaminas desde una aproximación nutricional. En ella se ha evaluado la influencia del método de cargado y del tipo de soporte de óxido de silicio utilizado (MCM-41, SBA-15, UVM-7 y Hollow Silica) en la eficacia de encapsulación de ácido fólico. En esta primera parte, también se ha evaluado la influencia de la morfología y el sistema de poros de los diferentes soportes en el perfil de liberación del ácido fólico desde los mismos. Los estudios de liberación de ácido fólico desde los diferentes soportes a diferentes valores de pH han demostrado que los sistemas diseñados son capaces de modular inteligentemente la liberación de ácido fólico en función del pH del medio (inhibición de la liberación a pH ácido -estómago-, liberación controlada a pH neutro -intestino-). Esta capacidad convierte a los sistemas liberación desarrollados en una alternativa excelente a la fortificación directa para modular exitosamente la bioaccesibilidad del ácido fólico a lo largo del tracto gastrointestinal. Por otra parte, se ha evaluado la estabilidad de los soportes durante un proceso de digestión in vitro, demostrando que si bien algunos soportes pueden ser atacados durante la digestión, la funcionalización con moléculas que actúan como puertas moleculares previene este ataque. Por último, los estudios de viabilidad celular llevados a cabo en cuatro tipos de líneas celulares demuestran que ni los soportes, ni los productos de degradación de los mismos durante el proceso de digestión in vitro promueven ningún tipo de toxicidad inespecífica. En la segunda parte se ha evaluado la influencia de la adición de diferentes soportes de óxido de silicio a dos matrices alimentarias, geles de gelatina y yogures. Esta aproximación tecnológica ha permitido conocer que la capacidad de estos sistemas inteligentes para liberar controladamente el ácido fólico a lo largo de un proceso de digestión in vitro se mantiene incluso tras su incorporación en yogures batidos. Por otra parte, se ha comprobado que el efecto de las matrices sobre las propiedades físicas de los geles, es dependiente tanto del tamaño de las partículas, como de su funcionalización y concentración. Por último, se ha comprobado que debido a la optimización del cargado de ácido fólico alcanzada en la primera parte de la tesis, se puede lograr una fortificación de un yogur con el 100% de la cantidad diaria recomendada de ácido fólico con una cantidad tan pequeña de sistema que ni las propiedades físico-químicas de un yogur, ni la viabilidad bacteriana se ven comprometidas. En resumen, se puede concluir que la presente tesis ha abordado de una manera global la encapsulación de ácido fólico en matrices porosas de óxido de silicio para ser utilizados en aplicaciones nutricionales y alimentarias incluyendo estudios de optimización de cargado, estudios de liberación en función del pH, digestiones in vitro, estudios de estabilidad de las matrices utilizadas, estudios de biocompatibilidad, así como estudios de la influencia de la adición de estos sistemas inteligentes en matrices alimentarias. Los resultados obtenidos han puesto de manifiesto que los sistemas inteligentes de liberación de ácido fólico desarrollados abren la puerta a una nueva manera de fortificar los alimentos sin comprometer sus características.
[CAT] La present tesi doctoral, que porta per títol "Encapsulació d'àcid fòlic en suports porosos d'òxid de silici: una aproximació nutricional i tecnològica" està centrada en el desenvolupament de nous sistemes intel·ligents de lliberació controlada d'àcid fòlic per a aplicacions nutricionals. La primera part de la tesi mostra l'encapsulació d'àcid fòlic en matrius poroses d'òxid de silici funcionalitzades amb poliamines des d'una aproximació nutricional. En esta part, s'ha avaluat la influència del mètode de carrega i del tipus de suport d'òxid de silici que s'ha emprat (MCM-41, SBA-15, UVM-7 i Hollow Silica) en l'eficàcia de l'encapsulació d'àcid fòlic. En esta primera part, també s'ha avaluat la influència de la morfologia i el sistema de porus dels diferents suports en el perfil d'alliberament de l'àcid fòlic des dels mateixos. Els estudis d'alliberament d'àcid fòlic des dels diferents suports a diferents valors de pH han demostrat que els sistemes dissenyats són capaços de modular intel¿ligentment l'alliberament d'àcid fòlic en funció del pH del medi (inhibició de l'alliberament a pH àcid -estómac-, alliberament controlat a pH neutre -intestí-). Esta capacitat fa dels sistemes desenvolupats una excel·lent alternativa a la fortificació directa per a modular amb èxit la bioaccessibilitat de l'àcid fòlic a través del tracte gastrointestinal. D'altra banda, s'ha avaluat l'estabilitat dels suports en un procés de digestió in vitro, demostrant que mentre que les partícules menudes poden ser atacades durant la digestió, la funcionalització amb molècules orgàniques que actuen com a portes moleculars prevé aquest atac. Per últim, els estudis de viabilitat cel·llular duts a terme en quatre tipus de línies cel·lulars demostren que ni els soports, ni els productes de degradació dels mateixos durant el procés de digestió in vitro promouen cap tipus de toxicitat inespecífica. En la segona part, s'ha avaluat la influència de l'addició de diferents sopors d'òxid de silici a dos matrius alimentàries, gels de gelatina i iogurts. Esta aproximació tecnològica ha permés conéixer que la capacitat d'aquests sistemes intel·ligents per alliberar controladament àcid fòlic durant un procés de digestió in vitro es manté fins i tot després de ser incorporats en iogurts batuts. D'altra banda, s'ha comprovat que l'efecte de les matrius sobre les propietats físiques dels gels, és dependent tant de la grandària de les partícules, com de la seua funcionalització i concentració. Per últim, s'ha comprovat que a causa de l'optimització del carregat d'acid fòlic alcançada en la primera part de la tesi, es pot aconseguir una fortificació d'un iogurt amb el 100% de la quantitat diària recomanada d'àcid fòlic amb una quantitat tan baixa del sistema que ni les propietats físico-químiques d'un iogurt, ni la viabilitat bacteriana se'n veuen compromeses. En resum, es pot concluir que en la present tesi s'ha abordat d'una manera global l'encapsulació d'àcid fòlic en matrius poroses d'òxid de silici per a ser utilitzades en aplicacions nutricionals i alimentàries, que inclouen estudis d'optimització de carregat, estudis d'alliberament en funció del pH, digestions in vitro, estudis d'estabilitat de les matrius utilitzades, estudis de biocompatibilitat, així com estudis de la influència de l'addició d'aquests sistemes en matrius alimentàries. Els resultats obtesos han posat de manifest de forma positiva que els sistemes intel·ligents d'àcid fòlic que s'han desenvolupat obrin una porta a una nova manera de fortificar els aliments sense comprometre les seues caracterísitiques.
Pérez Esteve, E. (2015). ENCAPSULATION OF FOLIC ACID IN MESOPOROUS SILICA SUPPORTS: A NUTRITIONAL AND TECHNOLOGICAL APPROACH [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/58613
TESIS
Premiado

Depression is a leading cause of disability and mortality worldwide, especially for women. No nutrition recommendations exist for depression. Oral contraceptives (OCs) have become the leading form of pregnancy prevention in the United States. Studies have associated OC use with impaired nutrient status, specifically folate, vitamin B₁₂, and vitamin B₆, which also affect brain functions. Dietary folate, vitamin B12, and vitamin B6 self-reported intakes were used to determine the relationship between depression in women who used OCs (n = 34) in a selected cohort ( n = 409) from the National Health and Nutrition Examination Survey, 2003–2008. OC users were more depressed than non-OC users; depression was associated with various quartile levels of vitamin intake (p <.001). No benefit was observed with intakes which exceeded RDAs for non-OC users; OC users were less depressed when intakes exceeded RDAs for folate, vitamin B₁₂, and vitamin B6 by 13%, 75%, and 7%, respectively.

Human milk contains many compounds, several of which are now known to play a key role in brain development. Sialic acid is a vital structural and functional component of brain gangliosides. As the requirement for sialic acid during the period of most rapid growth may outstrip the ability of the infant liver to synthesise it, diet may be an important source of sialic acid. We hypothesised that: 1. the milk of mothers of preterm infants is a richer source of sialic acid compared with either full term milk or standard or specialised preterm formulas. 2. levels of sialic acid in saliva (which is rich in sialic acid) is higher in breast-fed premature infants than those fed preterm formula. 3. levels of sialic acid in brain gangliosides will be higher in the human than any other animal species. 4. infants who died of SIDS, levels of sialic acid in brain gangliosides and glycoproteins of breast-fed infants will be higher than those of formula-fed children.

My thesis research has examined the fatty acid composition of serum triacylglycerol, phospholipid and cholesterol ester in 2793 participants who took part in the 1997 National Nutrition Survey - a national population-based survey of New Zealand adolescents and adults aged or [greater than or equal to]̲15 y. Differences in serum fatty acids by sex, age, ethnicity, body mass index and smoking - independent of dietary fat intake - were determined. Serum fatty acids were used as biomarkers of saturated and polyunsaturated fat intake to predict population serum total cholesterol concentrations. The association between n-3 long-chain polyunsaturated fatty acids in serum phospholipid and mental and physical wellbeing, as assessed by the short form-36, was determined. Serum fatty acids have been used as biological markers of fat intake and to predict the risk of disease. The fatty acid composition of serum triacylglycerol, phospholipid and cholesterol ester is subject to alteration by dietary fat but overall, is largely controlled by metabolic enzymes. Non-dietary variables - sex, age, body mass index or cigarette smoking - may influence the activity of these enzymes, which will subsequently alter the fatty acid composition but the extent to which these affect serum fatty acid composition in the general population is poorly understood. Our results showed that the proportion of docosahexaenoic acid in serum phospholipid and cholesterol ester was significantly greater in women by 0.15 and 0.02 mol%, respectively in comparison to men whereas, the proportion of eicosapentaenoic acid was significantly greater in men by 0.08 and 0.1 mol%, respectively, after adjusting for age, ethnicity, body mass index and smoking. A number of differences in the proportion of palmitoleic acid in serum triacylglycerol, phospholipid and cholesterol ester were detected; palmitoleic acid increased across the age categories in women (15-24, 25-44, 45-64 65+ y), was higher in women compared to men, New Zealand Europeans compared to New Zealand Maori and Pacific People, those with a body mass index or [greater than or equal to] 30 kg/m� compared to those with a body mass index < 25 kg/m� and in current smokers in comparison to non-smokers. In women, there was an inverse trend in the proportion of linoleic acid in serum phospholipid and cholesterol ester across the age categories. The proportion of linoleic acid in serum triacylglycerol, phospholipid and cholesterol ester was lower in smokers by 2.19, 1.04 and 0.75 mol%, respectively in comparison to non-smokers. None of these differences could be explained by a difference in dietary fat intake. Consequently, sex appears to affect the metabolism of n-3 long-chain polyunsaturated fatty acids independent of dietary fat intake and metabolic differences associated with age, body mass index and smoking may be at play for a number of other serum fatty acids notably, palmitoleic and linoleic acids. Evidence for a role of dietary fat as a predictor of serum cholesterol concentrations in the general population is conflicting. On one hand, results from cholesterol-lowering dietary intervention trials show unequivocally that decreasing saturated fat intake produces a meaningful reduction in serum cholesterol concentrations. On the other hand, the results of large observational studies show little association between saturated fat intake and cholesterol concentrations. The lack of association in the latter studies may result from errors in dietary assessment and therefore, using serum fatty acids as biomarkers of fat intake may overcome the limitations associated with typical dietary assessment techniques. Participants were divided into quintiles of increasing proportion of serum fatty acids. Each one SD increase in the myristic acid composition of serum cholesterol ester, triacylglycerol and phospholipid was associated with an increase in cholesterol of 0.19, 0.10 and 0.13 mmol/L, respectively after adjusting for confounding variables. The difference in cholesterol concentrations between those categorised into the highest and lowest quintiles of serum cholesterol ester myristate was 0.48 mmol/L. A one SD increase in the linoleic acid composition of serum cholesterol ester, triacylglycerol and phospholipid corresponded to a decrease in cholesterol of 0.07, 0.05 and 0.07 mmol/L, respectively. The difference in cholesterol concentrations between the 1st and 5th quintiles of serum cholesterol linoleate was 0.18 mmol/L. Intake of saturated and polyunsaturated fats, as measured using serum fatty acids, are important determinants of cholesterol concentrations in New Zealanders. It has been hypothesised that a lower intake of n-3 long-chain polyunsaturated fatty acids, largely of marine origin, is implicated in the aetiology of depressive disorder. Results from the majority of observational studies have shown that depressed participants have a lower proportion of eicosapentaenoic or docosahexaenoic acid in phospholipids compared to controls but evidence for an improvement in depressive symptoms after supplementation with n-3 long-chain polyunsaturated fatty acids is conflicting. There is little known about the role that n-3 long-chain polyunsaturated fatty acids may have as predictors of mental wellbeing in the general population. Participants were categorised into quintiles of increasing n-3 long-chain polyunsaturated fatty acids in serum phospholipid. There was no significant trend in self-reported mental wellbeing - the mental component score - across the quintiles of eicosapentaenoic, docosapentaenoic and docosahexaenoic acids or the sum of these three fatty acids after adjusting for confounding variables. There was a significant trend in the mental component score across the quintiles of the ratio of eicosapentaenoic/arachidonic acid; the difference between the highest and the lowest quintile was 6.6 points. There were significant positive trends in self-reported physical health - the physical component score - across the quintiles of eicosapentaenoic and docosapentaenoic acids as well as the ratio of eicosapentaenoic/arachidonic acid ratio; the difference between the 1st and 5th quintiles were 8.6, 6.0 and 8.9 points, respectively. Overall, there appears to be little association between the n-3 long-chain polyunsaturated fatty acid composition of serum phospholipid and self-reported mental health in a population of low fish consumers; however, the proportion of n-3 long-chain polyunsaturated fatty acids may be an important predictor of physical wellbeing in New Zealanders.

Folates are water-soluble B vitamins, which maintain DNA stability by regulating nucleotide synthesis and DNA methylation. Folates influence CRC risk and their ability to prevent or promote carcinogenesis may be dependent on several variables here investigated. No in vitro study has yet modelled the physiological folate status that human colon cells are exposed to in vivo. This study evaluates the ability of different forms and concentrations of folate to maintain DNA stability and normal cell function in folate-sufficient and stable human colonocytes and to modify DNA instability and the acquisition of abnormal characteristics in folate-deficient and genomically-unstable colonocytes. Non-malignant human NCM460 colonocytes cultured at physiologically-relevant concentrations of 5-methyl-THF or FA, representing the average deficient (2.5 ng/mL), sufficient (10 ng/mL) or highest post-supplementation (100 ng/mL) folate levels found in human plasma were used in this study as a model of colon-folate interaction. This work established that FA is taken up and/or retained to a lesser extent than 5-methylTHF and is less efficient at maintaining DNA stability and normal cellular characteristics in folate-sufficient and genomically-stable colonocytes at baseline, particularly at deficient and sufficient concentrations in the medium to longer term (14-21 days). During repletion of folate-deficient and genomically-unstable cells, sufficient concentrations of FA do not increase intracellular folate status and worsen the unstable phenotype, by perpetuating DNA instability and enabling the acquisition of a more pro-malignant protein expression. On the contrary, employing 5-methyl-THF sufficiency for repletion positively modifies the abnormal protein profile and morphological features of folate-deficient cells, mitigating potential progression to malignant transformation. When high post-supplementation concentrations are employed, both folate forms increase intracellular folate status, but drive a more promalignant and stress-induced proteome profile and, in the case of 5-methyl-THF, promote abnormal cell morphologies. In conclusion, the folate type, concentration employed, baseline folate status and timing of exposure to folate supplementation are important variables that should be taken into account by future studies evaluating the potential impact of mandatory FA fortification on CRC.

Background: Preterm birth is one of the leading causes of perinatal mortality and morbidity and poses extensive economic liability. The rate of preterm births globally is approximately 11.1%, and in the US, the preterm birth rate has been estimated to be 12-13%. Folate and B12 requirements increase during pregnancy as a result of increased cell division to accommodate maternal and fetal growth; inadequate levels can result in placental abnormalities and thus present implications for preterm birth. Objective: To investigate the association between red blood cell (RBC) folate and B12 concentrations with the risk of preterm birth. Methods: Study participants were recruited from Tampa General Hospital between January 2011 and May 2013. Women with a singleton delivery occurring less than 37 weeks gestation were classified as cases and those with a singleton delivery occurring between 37 and 42 weeks gestation were classified as controls. The study had a final sample size of 227 women, including 36 cases and 191 controls. Maternal blood was collected in order to measure folate and B12 concentrations. The association between folate/B12 and preterm birth was assessed using logistic regression; odds ratio (OR), 95% confidence interval (CI) and p values are reported. A power analysis was also performed using the available sample as well as imputation for missing values in the B12 variable. Results: Although not statistically significant, the mean concentration of folate and B12 levels were higher in the cases than in the controls, 894 ± 158.1 vs. 869.2 ± 169.6 and 245.2 ± 102.2 vs 238.3 ± 81.5, respectively. No significant associations were found between folate or B12 and the risk of preterm birth. Conclusions: This study did not detect a significant association between folate or B12 and preterm birth; however, due to the small sample size this analysis was underpowered. Additional studies are needed, preferably using a randomized control study design, in order to elucidate the relationship between folate/B12 and preterm births.

Neural tube defects (NTDs) occur at higher rates in Hispanic populations in the USA. Such populations would benefit from folic acid fortification of corn masa flour (CMF). This study evaluated folate stability in fortified CMFs and products made from the flours, tortillas and tortilla chips. There was no significant loss of folate during the six-month shelf-life of fortified tortilla CMF and tortilla chip CMF. There was a 13% loss (P < 0.05) of folate during tortilla baking and no loss during tortilla chip frying. Both tortillas and tortilla chips showed significant folate losses over the two-month shelf-life for these products, with a 17% loss in fortified tortillas and 9% loss in tortilla chips. Folate in fortified CMFs, tortillas and tortilla chips is relatively stable and comparable to the stability of folate in wheat flour and breads.

Mexico has a high prevalence of stunting in children and adolescents, due to poor nutrition. Paradoxically, too many Mexican children and adolescents are currently overweight or obese (OW/OB). The dual-burden of stunting (low height for age) and OW/OB are nutritional conditions that increase the risk of developing chronic degenerative diseases in adulthood. The persistence of high levels of stunting in southern regions of Mexico, such as Yucatan, may be due to diet changes (nutrition transition) that Yucatecan population has experienced in recent years. Vitamins, such as folic acid (FA) and VB12 are micronutrients necessary for normal metabolism and growth. The relationships between the intake of these micronutrients and growth rate were identified. The impact of micronutrient consumption on body composition was also investigated. The sample population comprised 273 adolescents (152 females) aged 10-18 years, from Merida, Mexico. Dietary information was obtained using a food frequency questionnaire (FFQ) covering 106 local foods. Anthropometric and body composition measurements were taken, and socioeconomic data were gathered. Data were collected between September 2011 and July 2012. Over 50% of participants had inadequate consumption of both vitamins: 64% had inadequate intake of FA and 69% of VB12. Almost half (46.9%) were either short or stunted, and 33% were at risk of OW/OB. A higher risk of presenting OW/OB was found for participants with FA intake less than the RDI of 400 μg/day and for those with VB12 intake less than the RDI of 2.4 μg/day. No relationship was found between body fat percentage and the consumption of FA or VB12.

Dietary fatty acid (FA) composition and energy restriction (ER) independently affect serum leptin levels; however it is not known whether this correlates with changes in obese (ob) gene expression. Herein, we assessed whether dietary FA composition and ER influence white adipose tissue (WAT) ob mRNA by Northern analysis. Animals consumed diets containing tallow (BT), safflower oil (SO) or fish oil (FO) ad libitum or at 60% ad libitum intakes. Serum leptin values were not different between levels of energy intake. ER decreased weight gain and WAT weights, which positively correlated with serum leptin values. WAT ob mRNA levels were in the rank order: FO > SO > BT in depots of all groups with ER showing a lower level of ob mRNA. Data show similarity in ob mRNA levels between depots with discordance in circulating leptin levels. These data suggest that energy restriction exerts greater control over leptin production than dietary fat source.

Objetivos: Estimar a prevalência de inadequação da ingestão de folato alimentar, assim como analisar esta prevalência considerando o ácido fólico proveniente da fortificação de alimentos em gestantes adultas. Casuística e métodos: Estudo observacional, com análise secundária de dados provenientes de um estudo prospectivo conduzido entre 103 gestantes usuárias de Unidades Básicas de Saúde (UBS) do município de Ribeirão Preto, SP. Foram incluídas no presente estudo todas as gestantes que apresentaram dados completos referentes ao consumo alimentar ao longo da gestação, totalizando 82 mulheres. Os dados dietéticos foram obtidos por meio de três inquéritos recordatórios de 24 horas (IR24H), durante a gravidez. A distribuição da ingestão habitual do folato alimentar e folato dietético, que corresponde ao folato alimentar adicionado ao ácido fólico proveniente da fortificação dos alimentos, foi ajustada pelo método do National Research Council (1986). Para estimar a prevalência de inadequação do nutriente empregou-se o método do requerimento médio estimado - Estimated Average Requirement (EAR) como ponto de corte. Resultados: Verificou-se que 100% das gestantes avaliadas não atingiram as recomendações nutricionais estabelecidas para o nutriente (EAR = 520 g DFE), quando foi considerado somente o folato alimentar. Ao analisar a ingestão do folato dietético, a prevalência de inadequação observada foi de 94%. Conclusão: As prevalências de inadequação da ingestão de folato alimentar, assim como a do folato dietético mostraram-se elevadas, identificando-se que a fortificação das farinhas com ácido fólico não repercutiu em melhoria da disponibilidade desta vitamina.
Objectives: To estimate the prevalence of inadequacy intake of food folate as well as analyze this prevalence considering the folic acid from flour fortification in pregnant woman. Methods: Observational study, with secondary analysis of data from a prospective study conducted among 103 pregnant women users of the Basic Health Units (BHU) of Ribeirão Preto, Brazil. Were included in this study all women who had complete data on the dietary intake during pregnancy, on total 82 women. Dietary data were obtained using three 24-hour dietary recalls (IR24H) during pregnancy. The distribution of the usual dietary intake of food folate and dietary folate, which corresponds to food folate added to the folic acid from the flour fortification, has been adjusted by the method of the National Research Council (1986). To estimate the prevalence of nutrient inadequacy employed the method of the estimated average requirement - Estimated Average Requirement (EAR) as the cutoff point. Results: It was found that 100% of pregnant women reported inadequate dietary intakes of food folate. Considering the intake of dietary folate, the prevalence of inadequacy observed was 94%. Conclusion: The prevalence of inadequacy intake of food folate, as well as the dietary folate were high, identifying the fortification of flour with folic acid did had little impact in improving the availability of this vitamin.

Many factors influence the nutrient composition of breast milk (BRM) particularly within the fatty acids composition. In this study BRM between 2-14 weeks of lactation was collected from 44 Caucasian women (24 normal weight (NW, BMI 18.5-24.9kg/m2) and 20 overweight (OW, BMI >25.0kg/m2). BRM was subjected to proximate analysis and participants completed food frequency questionnaires (FFQ) to estimate fruit, vegetable, and fat intake. BMI differed between NW and OW groups, 22.03 vs 33.86kg/m2 (p0.10) were identified for total calories (5,581.8 vs 5562.9cal/g), %fat (39.6 vs 43.9), or %protein (9.8 vs 8.9) for BRM in NW versus OW women as determined by proximal analysis. Gas chromatography of fatty acid methyl esters demonstrated NW BRM contained higher levels of omega-3, mono-unsaturated, and less palmitic acid fatty acids (p>0.10). The increased palmitic acid level seen in OW BRM may support increased de novo synthesis of fatty acids.

Microbiota are present in large numbers and as a diverse population within the gastrointestinal tract. There are approximately 400 different species of microbiota which may be beneficial, harmful or both, but each play an important role in the regulation and modulation of the hosts’ bowel processes (McOrist et al. 2008; Dethlefsen et al. 2008). Many of these colon microbiota allow for saccharolytic fermentation of non-digestible dietary fibres and carbohydrates into by-products and intermediates, followed by a subsequent conversion into short chain fatty acids (SCFAs) (mainly n-butyric acid, propionic acid and acetic acid) each of which play an important role in maintaining colon homeostasis (Topping & Clifton 2001). A balance of ‘good’ microbiota (e.g., Bacteroides spp./ Bifidobacteria spp.) and ‘bad’ microbiota (e.g., Veilonellae) and the optimal production of various SCFAs within the gut could possibly allow for proper functioning of the large intestine and assist in decreasing the onset of various colonic disorders such as Irritable Bowel Syndrome (IBS). The sample group for the study consists of male and female patients, with an average age of 40 to 50 years old, whom of which have been diagnosed with either constipation IBS (C-IBS) or diarrhoea IBS (D-IBS) via the Rome III criteria system for IBS diagnosis. DNA and SCFA extractions were optimised for human stool, colonic fluid and tissue biopsy sample obtained from the aforementioned patients. Optimization steps allowed for starting material with high analysis integrity. Different methods of microbiota analysis, such as ARISA, were investigated; however, real-time qPCR was selected as the best method to identify and quantify specific microbiota. Extracted SCFAs were separated via gas chromatography and identified and quantified via Mass Spectrometry. Significant changes in microbial content and SCFA profiles were found to be associated with healthy and IBS patients. Results obtained would however be influenced by external factors typical of clinical studies of this nature. This study allows for opportunities for future research into understanding IBS.

Hyperhomocysteinemia is a risk factor for cardiovascular disease and stroke. Nutritional and/or genetic disruptions in homocysteine metabolism can cause hyperhomocysteinemia. Mild methylenetetrahydrofolate reductase (MTHFR) deficiency due to the 677C → T mutation in the MTHFR gene is the most common genetic cause of hyperhomocysteinemia. The 677C → T variant is associated with an increased risk for neural tube defects, pregnancy complications, schizophrenia and Down syndrome, and with a decreased risk for colon cancer and leukemia. This variant is also a potential risk factor for vascular disease. Severe MTHFR deficiency results in homocystinuria, an inborn error of metabolism with neurological and vascular complications. We have generated mice with a knockout of the Mthfr gene. The Mthfr-deficient mice exhibit hyperhomocysteinemia and decreased methylation capacity. The Mthfr+/- mice appear normal, whereas the Mthfr-/- mice are smaller and have reduced survival. Abnormal external granule neuron development associated with increased cell death in the cerebellum was observed in the Mthfr-/- mice.
Evidence for cardiovascular pathology was obtained in several ways. Impaired aortic relaxation response to acetylcholine was seen in the Mthfr +/- mice fed a high methionine diet. Both Mthfr+/- and Mthfr-/- mice fed a low folate high methionine diet developed myocardial fibrosis in the left ventricle. Abnormal lipid deposition in the proximal portion of the aorta was observed in older Mthfr+/- and Mthfr-/- mice. After crossing Mthfr -deficient mice with apoE-null mice, we demonstrated that MTHFR deficiency promoted atherogenesis and its progression in the apoE-null mice.
Gene expression in brain of Mthfr-deficient mice was investigated via microarray analysis. Five genes with altered expression in the brain of Mthfr-/- mouse were validated by RT-PCR. In biochemical studies of human MTHFR, both FAD and folate were shown to stabilize the purified recombinant wild type and mutant MTHFRs from the baculovirus expression system against heat inactivation. The effect of folate appeared to be secondary to that of FAD, and S-adenosylmethionine (SAM) inhibited purified wild type and mutant MTHFRs with similar efficiency.
This dissertation will significantly contribute to our understanding of the role of MTHFR in human disease.

Hyperlipidemia caused by a diet high in saturated fat can lead to visceral fat weight gain, obesity, and metabolic syndrome. Being over-weight from visceral fat has been linked to increased risk of developing most age-related diseases and disability, along with a lower income potential and quality of life. However, researchers are just beginning to understand the biological mechanisms that regulate the conversion of excess calories into visceral fat storage rather than glycogen or muscle. Epidemiological studies have repeatedly shown a comorbid association between age-related diseases involving hyperlipemia and circulating levels of uric acid, but not a direct association. This study utilized archival data from 31 healthy, middle-aged adults, who participated in a randomized, double-blind, crossover clinical trial on blood markers of lipidemia and inflammation following a high saturated fat (HSF) verses a "healthy" polyunsaturated fat (PUFA) meal. This primary study was conducted and funded by the National Institute on Aging. A secondary analysis of this data using Pearson's correlation with least squares (2-tailed) regression modeling found that when stratified by gender, baseline uric acid level was an independent and significant predictor of the lipemic response from the HSF, but not the PUFA meal. The linear regression plots indicated that males with uric acid levels above 4.5, and females above 3.0 mg/dL, had a progressively increased lipemic response to the HSF meal. The public health utility of this finding may include the clinical use of the gender-specific linear regression plots of uric acid values to identify and advise individuals at risk for hyperlipidemia from a diet high in saturated fats.

Folate plays a role in the synthesis and repair of DNA and the generation of methyl groups. Folic acid (FA) is a synthetic oxidized form of folate used in food fortification and supplements in Canada. Increased colon cancer incidence has been correlated with FA fortification in several countries. The effect of FA on the development of colon cancer is controversial as other research shows a lack of association between FA fortification and colon cancer incidence. I hypothesize that FA affects proliferation and folate transporter expression in colon cancer cells differently than L-5-methyltetrahydrofolate (5MTHF). In addition, the forms of folate, reduced versus oxidized, would differentially affect the activity of the Wnt signaling pathway. The overall objective of my research is to investigate the effect of FA and 5MTHF on cell proliferation, the expression of selected folate transporters, and the activity of the Wnt signalling pathway in human colorectal adenocarcinoma (Caco2) cells. Caco2 cells were cultured for 3 or 5 days in folate-free RPMI 1640 medium supplemented with 10% dialyzed FBS and treated with 0, 0.9, 2.3, or 3.4 µM FA or MTHF. Cell viability was assessed using WST-1 colourimetric assay. Cell proliferation was assessed by BrdU colourimetric assay and cell cycle analysis with BrdU incorporation was measured by flow cytometry. The abundance of reduced folate transporter (RFC), folate receptor-α (FRα), proton-coupled folate transporter (PCFT), breast cancer resistance protein (BCRP) was assessed by Western blotting. β-Catenin nuclear localization was assessed by measuring the fluorescence of Alexa Fluor 488® using confocal microscopy. FA treatment increased cell proliferation compared to treatment with MTHF at all concentrations after 3 days. After 5 days, there was no difference in cell viability or cell proliferation. Cell cycle analysis after 5 days of 3.4 µM FA and 5MTHF treatment showed spikes in the pre-G1 phase compared to the control. Neither folate transporter expression nor β-Catenin nuclear localization was affected by FA and 5MTHF treatment under the conditions tested. This lack of effect of FA and 5MTHF on cell proliferation and the expression of selected folate transporters was possibly due to relatively short treatment duration.

This study investigated genetic predictions for amino acid biosynthesis and catabolism by Lactobacillus helveticus CNRZ 32, a commercial cheese flavor adjunct that reduces bitterness and intensifies flavor notes. Conversion of amino acids into volatile and nonvolatile flavor compounds by L. helveticus and other lactic acid bacteria in cheese is thought to represent the rate-limiting step in the development of mature cheese flavor and aroma. One of the primary mechanisms for amino acid breakdown by these microbes involves the reversible action of enzymes involved in biosynthetic pathways, so our group investigated the genetics of amino acid biosynthesis in L. helveticus CNRZ 32. Most lactic acid bacteria are auxotrophic for several amino acids, and phenotypic characterization of L. helveticus CNRZ 32 has shown this bacterium requires 14 amino acids. Reconstruction of amino acid biosynthetic pathways from a draft-quality (incomplete) genome sequence for L. helveticus CNRZ 32 showed generally good agreement between gene content and phenotypic amino acid requirements. One exception involved the requirement ofCNRZ 32 for Asp (or Asn) for growth, where predictions derived from the genome sequence suggested this strain may be able to synthesize Asp from citrate. This prediction was confirmed as Asp auxotrophy in L. helveticus CNRZ 32 could be alleviated by the addition of citrate to a chemically defined medium that lacked Asp and Asn. Genome analysis also predicted that L. helveticus CNRZ 32 possessed ornithine decarboxylase activity, and would therefore catalyze the conversion of ornithine to putrescine, a volatile biogenic amine. Putrescine production in cheese would be undesirable because this compound may impart a rotting flesh flavor and can also have adverse effects on human health. Experiments to confirm ornithine decarboxylase activity in L. helveticus CNRZ 32 using a special growth medium, thin layer chromatography, high performance liquid chromatograph, or 13C nuclear magnetic resonance were unsuccessful, however, which indicated this bacterium does not contribute to putrescine production in cheese.

The vitamin B-6 status of seemingly healthy adolescent girls was determined using several accepted and proposed parameters in an effort to establish guidelines for status evaluation. HPLC-derived plasma B-6 vitamer [pyridoxal phosphate (PLP), pyridoxine phosphate (PNP), pyridoxamine phosphate (PMP), pyridoxal (PL), pyridoxine (PN), and pyridoxamine (PM)] and 4-pyridoxic acid (4-PA) concentrations and urinary 4-PA levels of 28 white adolescent females, 12-15 years, having radiomonitored plasma PLP concentrations and coenzyme stimulation of erythrocyte alanine aminotransferase activities indicative of adequate status were determined. Mean daily vitamin B-6 and protein intakes of the subjects were 1.48 mg and 78.3 g, respectively. The ranges for plasma B-6 vitamer and 4-PA concentrations for these subjects which had seemingly adequate vitamin B-6 status were as follows: (nmol/L) PLP, 40.9-122.2; PNP, 0-16.1; PMP, 0-8.1; PL, 0- 15.0; PN, 0-21.9; PM, 0-17.8; and 4-PA, 0-55.7. PLP was the predominant plasma B-6 vitamer as well as being the only vitamer found in plasma of all subjects. Urinary 4-PA concentrations of the girls ranged from 0.11-2.50 pmol/mmol creatinine. The B-6 vitamer values of these white adolescent girls should be of use in the establishment of normal ranges for vitamin B-6 status parameters. HPLC methodologies seem to be advantageous for the rapid and accurate assessment of vitamin B-6 status.
Ph. D.

Includes bibliographical references (leaves 196-220) Studies the growth, body composition, feed intake of grazing animals, the use of anabolic agents, fatty acid composition of ruminants fats; and, the effect of saturated fat on human health.

Colon cancer is a leading cause of cancer related deaths worldwide. Lifestyle factors such as diet and exercise have been implicated as important agents in colon cancer development and progression. Epidemiological, in vivo and in vitro studies have found that n-3 polyunsaturated fatty acids (PUFAs) reduce colon carcinoma. The role of n-6 PUFAs remains a controversial topic, with studies indicating both promoting and preventing capabilities published. In order to better understand the effects of PUFAs on colon carcinoma, it is important to have an understanding of how they will be broken down in the body. During this study, in silico metabolism of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA) predicted the formation of hydroxy-, di-hydroxy- and epoxy-FAs. A gas chromatography-mass spectrometry method was developed and validated for the detection of these PUFAs and their cytochrome P450 (CYP) metabolites. A human liver microsomal system for the in vitro metabolism of EPA, DHA and AA was optimised in terms of microsomal and PUFA concentration. The system resulted in the metabolism of the positive control, lauric acid, to 12-hydroxy-lauric acid but was unable to metabolise the PUFAs of interest. EPA, DHA and AA reduced cell viability in the colon carcinoma cell lines SW480 and SW620 in the micromolar concentration range (25 – 200 μM). The CYP epoxidation metabolite of EPA, 17, 18-epoxyeicosatetraenoic acid (17, 18-EpETE) resulted in a significant reduction in SW480 cell viability relative to the parent compound at lower concentrations (25 and 50 μM). Annexin V apoptosis analysis revealed that EPA and 17, 18- EpETE did not result in apoptosis in SW480 cells at a concentration of 25 μM and over an incubation period of 24 hours. A significant reduction in reactive oxygen species production was seen in SW480 cells after incubation with 25 μM 17, 18-EpETE for 24 hours. EPA and 17, 18-EpETE were implicated in the reduction of colon cancer metastasis since they were able to reduce SW480 migration and anchorage independent cell growth. These results indicate that the dietary intake of EPA, DHA and AA may be beneficial to one’s health due to the negative effects that these PUFAs had on colon carcinoma. Future studies are needed to confirm these benefits and compare the effects of the PUFAs to their CYP-metabolites.

The purpose of this study was to analyze the effect of fatty acid chain length and quantity on the bioavailability of calcium. Thirteen healthy subjects were randomly assigned to a series of 5 test meals containing varying types and levels of fat and calciumconsumed over a three week time period. The test meals included 10 grams MCT oil (MCT 10), 20 grams MCT oil (MCT 20), 10 grams beef fat (BT 10), 20 grams beef fat (BT 20), and calcium only (Ca). Calcium absorption was assessed using timed urine collections following a specified calcium load. Three day food records were obtained to assess typical nutrient intakes of the subjects coming into and during the study. MCT oil provided better absorption of the calcium supplement than did the beef tallow. A difference was also noted in the absorption of calcium based on the amount of fat consumed. A higher intake of MCT oil (10 g vs. 20 g) appeared to favor the absorption of calcium. Urine calcium excretion was significantly greater (p < .009) during the MCT oil treatments (MCT 10, MCT 20) compared to the beef fat treatments (BT 10, BT 20), suggesting reduced calcium absorption during the beef fat treatments. There were no differences in mean calcium excretion based on quantity of fat consumed ( 10 g vs. 20 g), nor any interaction between type of fat and amount. Tests for detecting differences between individual treatments indicated a significance difference (p < .05) in calcium excretion between MCT 20 and BT 10 treatments. Urine calcium excretion was corrected for body size using urine calcium/creatinine ratio (Ca/Cr). There was a significant time effect between the 0 - 2, 2 - 4 hour time periods (p < .005) and the various treatments for Ca/Cr. Though not significant, mean Ca/Cr was highest for the calcium treatment (0.42), compared to the MCT oil treatments (36, z of MCT 10 & MCT 20), and beef fat treatments (28, x of BT 10 & BT 20). The beef fat treatments significantly decreased the absorption of calcium compared to the MCT oil treatments. It appears that beef fat, when compared to the calcium only treatment, decreased calcium absorption.
Department of Home Economics

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.

Thesis (M.S.)--West Virginia University, 2009.
Title from document title page. Document formatted into pages; contains vii, 42 p. : ill. Includes abstract. Includes bibliographical references (p. 29-35).

Computer-mediated communication [CMC] is beginning to be used more frequently in traditional classrooms. A group of physical chemistry professors have developed Physical Chemistry On-Line [PCOL] modules designed to augment in-class instruction and engage students at geographically dispersed institutions in activities to help them learn physical chemistry concepts. These modules use context-rich scenarios with a guided-inquiry approach, and the WWW and e-mail for information distribution and communication. This allows for intra- and inter-institutional collaboration between module participants. Three modules implemented during the Fall 2000 term are evaluated in this study. In order to assess the effectiveness of PCOL, each student completed a pre-module and post-module survey, pre-module and post-module content questions, and participated in an online discussion group. The primary focus of this analysis was to determine the student's: 1) perception of on-line activities, 2) perception of on-line interactions, and 3) use of computers.
School of Physical Education

Thesis (PhD (Food Science))--University of Stellenbosch, 2006.
Long-chain polyunsaturated fatty acids (LCPUFA), especially the n-3 LCPUFA metabolic products eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) play an important role as regulators in many biological processes. To date hake (Merluccius capensis) heads, a rich source of EPA and DHA, have been discarded at sea. The South African Fisheries Policy Development Committee concerned with the environmental impact of this practice has rendered it undesirable. The high prevalence of under-nutrition amongst children in South Africa can be addressed by the supplementation of their diet with this unexploited fish source. The aim of the current study was to develop a microbiologically safe and sensory acceptable sandwich spread using fish flour prepared from fish heads, as a prime ingredient. The intervention trial aimed to compare the effects of an increased dietary intake of n-3 LCPUFA, specifically DHA, on the blood fatty acid levels and absenteeism (as indicator of immune function), as well as the cognitive status, of the subjects. The microbiological content of the sandwich spread was determined after storage for 20 d at 5°C and 15 d at 25°C. Sensory evaluation was performed by consumers (n = 95; M:F = 44:51; 6 – 9 yr) to determine acceptance of the five different flavours individually incorporated into the sandwich spread to mask the fishy note and to provide different flavour options. For the intervention trial subjects (n = 351) were stratified within class group (A - E) and gender and randomly assigned to two treatment categories, an experimental group (EG; n = 174) receiving 25 g sandwich spread.d-1 (191.66 mg DHA. d-1) and a control group (CG; n = 177) receiving an analogous placebo. On school days (104 d), each subject received two sandwiches consisting of two slices of bread (ca. 60 g), spread with 25 g of either the placebo or the experimental spread. Blood samples were drawn at baseline and post intervention. Plasma fatty acid and red blood cell (RBC) membrane status, C-reactive protein levels, as well as vitamin and micronutrient status, were determined. Trained test administrators conducted a battery of cognitive tests. According to South African Government health standards, the sandwich spread remained microbiologically safe after storage. Male and female consumer respondents revealed a significant difference between gender preferences of the five different spread flavours (p <0.05). Significant treatment effects (p <0.05) were observed in n-3 LCPUFA status of the EG, as well as for their absenteeism from school. The two subtests of the Hopkins Verbal Learning test, Recognition and Discrimination Index, showed significant differences between the EG and CG (p <0.05) post intervention in the Grade 2 subjects. The Spelling tests also showed a significant difference between the two groups (p <0.05). In the current study a microbiologically safe and sensory acceptable sandwich spread was developed and tested during an intervention trial, and could possibly in future, provide a healthier option in the School Nutritional Programme. This study proved that supplementation of children (6 - 9 yr) with n-3 LCPUFA, with specific reference to EPA and DHA from a marine source, could have a beneficial effect on their fatty acid status and absenteeism from school. Based on the outcomes of the Hopkins Verbal Learning test and Spelling test, the current study proved that an n-3 fatty acid-rich spread improved the learning ability and memory of children.