Dissertations / Theses: 'Fatty acids (Analysis; Determination)'

1

Jenske, Ramona. "Compound specific and enantioselective determination of 2- and 3-hydroxy fatty acids in food." Aachen Shaker, 2009. http://d-nb.info/996919910/04.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Gao, Lei. "Determination of quantitative nutritional labeling compositional data of lipids by Nuclear Magnetic Resonance (NMR) spectroscopy." Thesis, McGill University, 2008. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=111577.

Full text

Abstract:

The application of Nuclear Magnetic Resonance (NMR) spectroscopy in the determination of nutrition labeling component data (NLCD) was investigated, with the intent of using this methodology as a primary method to calibrate FTIR instrumentation for NLCD confirmation or screening on a routine basis. Unlike previous NMR studies, this work used three strategies to attain accuracy and reproducibility of NLCD through: (i) appropriate setting of operational parameters for spectral acquisition; (ii) resonance selection by optimizing the signal in proportion to the nuclei population and (iii) integration of resonances by pre-defined fixed chemical shift ranges. Both of 13C NMR spectra and 1H NMR spectra were shown to provide robust and acceptable results on the condition of appropriate acquisition of spectra for quantization purposes and the adoption of standard procedures for spectral processing, integration and calculation purposes. A quantitative approach of NLCD including trans content was determined by the interpretation resonance signals of 13C's and 1H's from methylene groups presented in triglyceride complex of fats and oils. An alternative method based on partial-least-squares (PLS) calibrations was provided as well, the latter proved to be especially useful in dealing with overlapping bands frequently found in 1H spectra. With the diagnostic provided by PLS, the trans and cis signals were shown to be separated in 1H spectra. It is the premise for the trans fat determination based on 1H spectra. Unit conversion from mole to weight % was addressed and a solution was developed based on NMR data per se, without significant assumptions. Validation involving the analysis of three different lipid types (model triacylglycerols, refined and hydrogenated oils) demonstrated that NMR predictions of NLCD were in good agreement with those results either from samples' actual values as well as those obtained using GC and FTIR predictions. Thus with appropriate integration of instrumentation, software and spectral processing accessories, both 13C and 1H NMR can determine NLCD, but with the capability to determine trans, 1H NMR is more practical than 13C NMR due to its much shorter spectral acquisition time. Thus NMR can serve as a primary method for the calibration of FTIR instrumentation, a practical instrumental method for routine NLCD determination and screening.

APA, Harvard, Vancouver, ISO, and other styles

3

Al-Alawi, Ahmed Ali. "Novel approaches to automated quality control analyses of edible oils by Fourier transform infrared spectroscopy : determination of free fatty acid and moisture content." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100311.

Full text

Abstract:

Three new quantitative Fourier transform infrared (FTIR) spectroscopic methods were developed for the analysis of edible oils: two procedures to measure free fatty acids (FFA) and one to measure moisture (H2O), the latter two methods ultimately being automated and implemented on an auto-sampler equipped FTIR spectrometer. The methods developed for FFA determination both convert FFAs to their carboxylate salts by means of acid/base reaction without causing oil saponification, one approach using 1-propanol, an oil-miscible solvent, and the other using methanol, an oil-immiscible solvent into which the FFA salts are extracted. The first method involves splitting oil samples into two halves, with one half treated with propanol containing base and the other half with propanol only. The spectra of each half is collected and a differential spectrum obtained, from which quantization is performed. The methanol procedure simply involves extracting FFA into methanol containing a weak base and quantitating the FFA salts produced. Both FFA methods determine the FFA content by measuring the v (COO-) absorbance at ∼1570 cm-1 relative to a reference wavelength of 1820 cm-1 from a differential spectrum relative to the solvent, the extraction procedure being superior in terms of both speed and sensitivity, being able to measure FFA levels down to ∼0.001%. The method developed for moisture determination involves extracting water in edible oils into dry acetonitrile and then quantitating it by measuring the absorbance of the OH stretching band (3629 cm-1) and/or the HOH bending band (1631 cm -1). All three methods were validated by standard addition experiments, evaluated for potential interferences, and, in the case of FFA determination, compared to the performance of AOCS official methods. The results indicated that the extraction-based procedures were superior to conventional wet chemical methods in both sensitivity and reproducibility. The FFA and H2O extraction procedures were subsequently automated by connecting an auto-sampler to the FTIR spectrometer and developing procedures and software algorithms to enable the analysis of up to 100 samples/h. The methods developed and implemented are a substantive improvement over conventional methods for the analysis of FFA and H2O in edible oils and provide a means by which QC and process laboratories can analyze large volumes of edible oils for these two important parameters.

APA, Harvard, Vancouver, ISO, and other styles

4

Oliveira, Claudimar de Jesus. "Avaliação comparativa, \"in vitro\" e \"in vivo\", das propriedades antioxidantes da dieta do estado de São Paulo com a Dieta Mediterrânea." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/9/9132/tde-22092017-110415/.

Full text

Abstract:

O bom funcionamento do organismo está intimamente relacionado com o consumo alimentar, pois através dos alimentos obtemos os nutrientes essenciais para processos biológicos vitais. Várias pesquisas vêm sendo realizadas com a finalidade de se determinar a atividade antioxidante de compostos em alimentos e de forma geral, condutas e hábitos alimentares. Alguns padrões dietéticos são seguidos como modelo, sendo o caso da Dieta Mediterrânea. No presente estudo, avaliou-se a atividade antioxidante de rações alimentares (comumente denominadas dietas) consumidas em duas localidades: 1) estado de São Paulo e 2) Grécia. As rações foram elaboradas com alimentos coccionados e alimentos in natura, inerentes a cada população, obtidos através de relatórios de órgãos oficiais - Instituto Brasileiro de Geografia e Estatística (IBGE) e Eurapean Commission (Health Monitoring Programme - Data Food Networking - DAFNE). Após processamento, esses alimentos foram liofilizados e então, triturados. Para determinação da atividade antioxidante in vitro, alíquotas das rações foram desengorduradas, devido à natureza dos ensaios antioxidantes in vitro. Para determinação da atividade antioxidante in vitro foram realizados dois ensaios: cooxidação β-caroteno/ácido linoléico e 2,2-difenil-picrilhidrazil (DPPH). Além da atividade antioxidante in vitro, foram executados ensaios nas dietas para a determinação da composição centesimal, perfil de ácidos graxos e determinação dos compostos fenólicos totais. Após esse delineamento, realizou-se o ensaio biológico, onde foram utilizados 30 ratos machos, da linhagem Wistar, recém desmamados e submetidos a 30 dias de tratamento, sob condições ambientais controladas, após os quais, os animais foram sacrificados para a retirada de cérebro, fígado e plasma. Ensaios foram realizados nesses tecidos com a finalidade de se avaliar a eficácia da conduta dietoterápica: atividade de enzimas antioxidantes em tecidos alvo (fígado e cérebro), peroxidação de tecidos (fígado, cérebro e plasma) e perfil de ácidos graxos (fígado, cérebro e plasma). Os resultados obtidos indicaram que as duas dietas estudadas mantiveram a integridade orgânica. Um fato relevante é que a dieta do Estado de São Paulo foi composta por alimentos acessíveis e de hábito regular na população nacional estudada, sendo essa equiparada qualitativamente com a Dieta Mediterrânea, uma referência mundial. A Dieta Nacional do Estado de São Paulo (DNSP) possui atividade antioxidante similar à Dieta Mediterrânea (DM), utilizada como modelo de referência.
The good operation of the organism is intimately related with the alimentary consumption , since through the victuals we obtain essential nutrients for vital biological processes. Several researches have been accomplished with the purpose of being determined the antioxidant activity of composed in victuals and of general form, conducts and alimentary habits. Some dietary patterns are followed as model, being the case of the Mediterranean Diet. In the present study, the antioxidant activity of alimentary diets was evaluated (commonly denominated diets) consumed at two places: 1) state of São Paulo and 2) Greece. The diets were elaborated with victuals cooked and victuals in natura, inherent to each population, obtained through reports of official organs - Brazilian Institute of Geography and Statistics (IBGE) and European Commission (Health Monitoring Programme - it Dates Food Networking -DAFNE). After processing, those victuals were Iyophilized and then, triturated. For determination of the activity antioxidant in vitro, aliquots of the rations were degreased, due to the nature of the tests antioxidant in vitro. For determination of the activity antioxidant in vitro two rehearsals were accomplished: co-oxidation of linoléico acid and β-carotene and 2,2-difenil-picrilhidrazil (DPPH). Besides activity antioxidant in vitro, were made executed in the diets for the determination of the centesimal composition, profile of fat acids and determination of compositions total phenolics compounds. After that out line, took place the biological rehearsal, where 30 male mice were used, of the lineage Wistar, recently weaned and submitted to 30 days of treatment, under controlled environmental conditions, after the ones which, the animals were sacrificed for the brain retreat, liver and it shapes. Rehearsals were accomplished in those tissues with the purpose of evaluating the effectiveness of the diets: activity of antioxidant enzymes in woven objective (Iiver and brain), peroxidation of tissues (Iiver, brain and it shapes) and profile of fat acids (Iiver, brain and it shapes). The obtained results indicated that the two studied diets maintained the organic integrity. An important fact is that the diet of the State of São Paulo was composed by accessible victuals and of regular habit in the studied national population, being that comparison qualitative with the Mediterranean Diet, a world reference. The National Diet of the State of São Paulo (DNSP) it possesses similar antioxidant activity to a reference model, Mediterranean Diet (DM).

APA, Harvard, Vancouver, ISO, and other styles

5

Marais, Christiaan De Wet. "The determination of cis and trans fatty acid isomers in partially hodrogenated plant oils /." Link to online version, 2007. http://hdl.handle.net/10019/399.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Heijden, Luuk van der. "Determination of the food sources and of the role of meiofauna in soft-bottom intertidal habitats of the Marennes-Oléron Bay, France, and the Sylt-Rømø Bight, Germany : importance of the microphytobenthos-meiofauna pathway, highlighted by community structure, trophic markers and linear inverse food web models." Thesis, La Rochelle, 2018. http://www.theses.fr/2018LAROS030/document.

Full text

Abstract:

La méiofaune joue un rôle important dans le fonctionnement des habitats benthiques à substrat meuble (ex. flux de matière) en relation avec sa production élevée, sa position trophique intermédiaire et les importants transferts d’énergie vers les niveaux trophiques supérieurs qui y sont lié. Les relations trophiques et les flux de matière organique liés à la méiofaune restent néanmoins mal connus ou peu pris en compte. Afin de mieux appréhender le rôle de la méiofaune, la structure des communautés et les relations trophiques entre les sources de nourriture et ces consommateurs ont été déterminées dans cinq habitats à substrat meuble (i.e., vasière nue, herbier, zone à sables) de la baie de Marennes-Oléron, France, et de la baie de Sylt-Rømø, Allemagne, en tenant compte des variations temporelles. Le peuplement de méiofaune s’est trouvé être dominé par les nématodes et les copépodes benthiques. Les biomasses de microphytobenthos et de matière organique du sédiment sont apparues comme étant deux facteurs structurants pour les communautés. L’utilisation combinée de différents traceurs de la matière (i.e., isotopes stables, acides gras) a démontré que le microphytobenthos et les bactéries étaient les ressources trophiques majeures de la méiofaune dans les cinq habitats étudiés. Les mesures réalisées sur la structure des communautés et les données issues des traceurs de la matière ont été implémentées dans des modèles de réseaux trophiques. Dans tous les habitats, ces modèles ont mis en évidence que le flux de carbone dominant était issu du microphytobenthos, ceci démontrant les très faibles changements de comportements alimentaires malgré les importantes différences de sources trophiques en termes de disponibilité et de production des sources de nourriture entre ces différents habitats. Tous les groupes trophiques de nématodes, à l’exception des déposivores sélectifs, étaient particulièrement sélectifs et s’alimentaient majoritairement à partir de microphytobenthos, ceci étant à l’origine d’une forte production et d’un court temps de renouvellement de la méiofaune. En conclusion, cette thèse démontre le rôle important de la méiofaune dans les habitats à substrat meuble ainsi que l’importance de la relation trophique entre le microphytobenthos et la méiofaune dans le fonctionnement de ces réseaux trophiques
Meiofauna play an important role in ecosystem processes in soft-bottom benthic habitats, e.g. food web dynamics, related to their highproduction, their intermediate trophic position and the energy they transfer towards higher trophic levels. The trophic linkages and flows of organic matter related to the meiofauna remain poorly known or taken into account. To better assess the role of meiofauna, the community structure and trophic relationships between food sources and meiofauna were determined in five intertidal soft-bottom habitats (i.e., mudflat, seagrass bed, sandflat) of the Marennes-Oléron Bay, France, and the Sylt-Rømø Bight, Germany, taking temporal variations into account. Meiofauna communities were dominated by nematodes and benthic copepods. Biomass of microphytobenthos and of sediment organic matter were two of the major drivers of community structure. The combination of trophic markers (i.e., stable isotopes, fatty acids) demonstrated that microphytobenthos and bacteria were the major food sources of meiofauna in the five habitats. Information from community structure assessments and trophic marker analyses were implemented in food web models. In all habitats, these models demonstrated that the main flow of carbon to meiofauna originated from microphytobenthos, highlighting negligible changes in meiofauna feeding behavior besides the large differences in availability and productivity of food sources between these habitats. All trophic groups of nematodes, except for selective deposit feeding nematodes, were highly selective and mainly fed on microphytobenthos, resulting in a high production and a short turn-over time of meiofauna. In conclusion, this thesis demonstrated the important role of meiofauna in soft-bottom habitats as well as the importance of the trophic pathway from microphytobenthos to meiofauna in the functioning of these food webs

APA, Harvard, Vancouver, ISO, and other styles

7

Thambugala, Dinushika. "Analysis of genetic diversity and expression of genes involved in fatty acid composition in flax (Linum usitatissimum L.) and comparative genomic analysis of their loci." Theoretical and Applied Genetics, 2013. http://hdl.handle.net/1993/30665.

Full text

Abstract:

Flax (Linum usitatissimum L.) is one of the richest plant sources of omega-3 fatty acids praised for their health benefits. In this study, the extent of the genetic variability for genes encoding stearoyl-ACP desaturase (SAD), fatty acid desaturase 2 (FAD2) and 3 (FAD3) was determined by sequencing the six paralogous genes from 120 flax accessions representing a broad range of germplasm including some EMS mutant lines. A total of 6 alleles for sad1 and sad2, 21 for fad2a, 5 for fad2b, 15 for fad3a and 18 for fad3b were identified. Deduced amino acid sequences of the alleles predicted 4, 2, 3, 4, 6, and 7 isoforms, respectively. Allele frequencies varied greatly across genes. Fad3a, with 110 SNPs and 19 indels, and fad3b, with 50 SNPs and 5 indels, showed the highest levels of genetic variation. While most of the SNPs and all the indels were silent mutations, both genes carried non-sense SNP mutations resulting in premature stop codons, a feature not observed in sad and fad2 genes. Some alleles and isoforms discovered in induced mutant lines were absent in the natural germplasm. Correlation of these genotypic data with fatty acid composition data of 120 flax accessions phenotyped in six field experiments revealed statistically significant correlations of some of the SAD and FAD isoforms on fatty acid composition, oil content and iodine value. The novel allelic variants and isoforms identified for the six desaturases will be a resource for the development of oilseed flax with unique and useful fatty acid profiles.
October 2015

APA, Harvard, Vancouver, ISO, and other styles

8

Jenske, Ramona [Verfasser]. "Compound-Specific and Enantioselective Determination of 2- and 3-Hydroxy Fatty Acids in Food / Ramona Jenske." Aachen : Shaker, 2009. http://d-nb.info/1159835012/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Skinner, Joanna P. "Determination of Oxidized Lipids in Commonly Consumed Foods and Their Binding Affinity for PPARγ." Digital Archive @ GSU, 2012. http://digitalarchive.gsu.edu/nutrition_theses/32.

Full text

Abstract:

Background: Foods rich in polyunsaturated fatty acids (PUFA) are susceptible to oxidation through heating or storage. Oxidized lipids are known to act as ligands for a transcription factor (PPAR-gamma) that affects adipocyte differentiation and insulin sensitivity. Objective: The purpose of this study was to determine the amounts of oxidation products of a variety of PUFA containing foods over time, and to determine whether extracted fats from these foods act as ligands for PPAR-gamma. Method: To study the effect of room-temperature storage on oxidation, 5 foods (walnuts, sunflower seeds, ground flax, fish oil capsules, and infant formula) were purchased and stored at room temperature for 1, 2, and 3 months. To determine oxidation levels in fried foods, French fries and chicken nuggets were used. Fat was extracted from each food and the levels of oxidation products were analyzed by spectrophotometry and kits designed to measure oxidation products. Using a fluorescence polarization-based ligand screening assay kit, fat extracted from foods was analyzed for its binding affinity for PPAR-gamma. Results: Among foods stored at room temperature, the levels of oxidation products did not change significantly with time. Most foods exhibited the highest levels of oxidation at the purchase date. Infant formula and ground flax demonstrated higher levels of oxidation products than did other foods. In preliminary ligand binding assays, extracted fat from French fries showed the greatest binding affinity for PPAR-gamma; a select few other oils showed slight affinity. Discussion: Surprisingly, storage time did not affect oxidation levels. The greatest amount of oxidation may occur during pre-purchase storage conditions. The processing of formula and ground flax may be the cause of the relatively higher oxidation levels in those foods. The binding affinity for PPAR-gamma demonstrated by French fries needs further investigation. Conclusion: Certain oxidized lipids from foods may act as ligands for PPAR-gamma. Further research is required not only to determine which component of these PUFA-containing foods activates PPAR-gamma but also to determine whether that component acts as an agonist or antagonist for PPAR-gamma.

APA, Harvard, Vancouver, ISO, and other styles

10

Bhagdeo, Mansi Pravin. "Determination of Extractables from Cranberry Seeds Using Supercritical CO₂." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/9989.

Full text

Abstract:

An alternative method for extraction of therapeutically beneficial compounds such as sterols, fatty acids, and tocopherols from cranberry seeds with pure SF CO2 has been provided. The supercritical fluid extraction (SFE) operating conditions such as extraction temperature, pressure of CO2, extraction time, and CO2 flow rate were optimized to maximize the extraction yield. The amount and type of SF extractables (pure CO₂) have been compared with Soxhlet extractables (hexane) to evaluate the feasibility of SFE as an alternative extraction method. The extractables obtained via hexane and SF CO₂, which were derivatized and identified by gas chromatography mass spectrometry (GC-MS), contained mostly methylated fatty acids.
Master of Science

APA, Harvard, Vancouver, ISO, and other styles

11

Chivall, David. "Compound-specific hydrogen isotope analysis of animal fatty acids for palaeodietary reconstruction." Thesis, University of Bristol, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446151.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Marais, Christiaan De Wet. "The determination of cis and trans fatty acid isomers in partially hydrogenated plant oils." Thesis, Stellenbosch : University of Stellenbosch, 2007. http://hdl.handle.net/10019.1/2628.

Full text

Abstract:

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2007.
Trans isomers are formed during the partial hydrogenation process of cis unsaturated fatty acids. The major source of trans fatty acids in the normal person's diet is from margarines and shortenings made from these partially hydrogenated plant and marine oils. In addition to influencing lipid risk factors for cardiovascular disease, trans fatty acids have also been implicated in breast cancer, and in poor fetal development and reduced early infant growth. In reality, trans fatty acids have been consumed for centuries, since they occur naturally in beef, mutton, butter, milk and other dairy products. Though it has been shown that these naturally occurring trans fatty acids have different effects on the health of humans. With the implementation of the new labelling law in South Africa, the trans fatty acids content of food items must be displayed on the food label. Therefore, it becomes necessary to optimise the analytical methodology for the determination of trans fatty acids in foods. Many publications have reported on the quantification of the total concentration of trans fatty acids in food samples, while less work has been done on the identification and quantification of the different cis and trans unsaturated fatty acid isomers found in foods made from partially hydrogenated oils. The objective of this study was to standardise and optimise an analytical technique to identify and quantify the different cis and trans mono-unsaturated fatty acid isomers in local margarines and bread spreads. Seeing that fatty acids are the group of lipids most commonly analysed by GLC and the availability of highly polar capillary columns bonded with cyanoalkyl polysiloxan phases, it was decided to use GLC for the identification and quantification of the different cis and trans isomers in a selected group of margarines. It was further decided to evaluate two BPX-70 capillary columns packed with cyanoalkyl polysiloxan phases. The one a 30 m BPX-70 capillary column, normally used for routine fatty acid analyses, and the other a 120 m BPX-70 capillary column.

APA, Harvard, Vancouver, ISO, and other styles

13

Åkesson, Nilsson Gunilla. "Determination of chlorinated fatty acids using SPE, XSD and GC/MS with particular regard to cultured human cells /." Uppsala : Dept. of Environmental Assessment, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/a493.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Jor, Wing-yan Irene. "Proteomic analysis of the effects of omega-3 fatty acids on human hepatocarcinoma." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/b40204042.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Jor, Wing-yan Irene, and 左穎欣. "Proteomic analysis of the effects of omega-3 fatty acids on human hepatocarcinoma." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40204042.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Lao, Hongbai. "A study of the synthesis and properties of some long chain fatty acid esters containing azido, amino, amido and amino acid residues and the analysis of some seed oils used in Chinese medicine /." [Hong Kong : University of Hong Kong], 1989. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12437141.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Abdalla, A. El-S. M. "Fatty acids in germinating seeds of sunflower (Helianthus annuus) and cotton (Gossypium barbadense)." Thesis, University of Glasgow, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380400.

Full text

APA, Harvard, Vancouver, ISO, and other styles

18

Enros, Erin. "Amniotic fluid fatty acids and cholesterol and their association with pregnancy outcomes." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99341.

Full text

Abstract:

The objectives were (1) to establish a profile of total fatty acids and cholesterol in amniotic fluid (AF) as well as (2) to determine possible associations between AT fatty acids (micromolar and relative proportion) with gestational age and birth weight. A total of 208 AF samples collected between 12 and 22 weeks of gestation during routine amniocentesis were analyzed using tandem column gas chromatography (GC). Smoking increased AF polyunsaturated fatty acid (PUFAs) levels while developmental stage and storage time decreased AF fatty acid quantities. AF trans fatty acids (TFAs) were negatively associated with both birth outcomes, whereas specific fatty acids including stearic acid (C18:0) and gondoic acid (C20:1n-9) were identified as negative predictors for gestational age and birth weight respectively. This study demonstrated novel relationships between fatty acids and fetal growth and gestational age in early midgestation AF, suggesting a possible role of AF fatty acids in predicting birth outcomes.

APA, Harvard, Vancouver, ISO, and other styles

19

Bourne, Thomas Franklin. "Analysis of in situ methylated microbial fatty acids by pyrolysis gas chromatography - mass spectrometry." Thesis, Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/25384.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Li, Zhiguo. "High-performance liquid chromatography analysis of fatty acids and mathematical modeling of liquid chromatography." Ohio : Ohio University, 2001. http://www.ohiolink.edu/etd/view.cgi?ohiou1179157379.

Full text

APA, Harvard, Vancouver, ISO, and other styles

21

Li, Zhiguo. "High-performance liquid chromotography analysis of fatty acids and mathematical modeling of liquid chromotography." Ohio University / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1179157379.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Lam, Chi-chung. "Nuclear magnetic resonance spectroscopy as an analytical tool in the structural analysis of triacylglycerols /." [Hong Kong : University of Hong Kong], 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13787056.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Penugonda, Kavitha. "Determination of bioavailable iron and vitamin A in fortified blended foods and fatty acids and phytosterols in saw palmetto supplements." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/20603.

Full text

Abstract:

Doctor of Philosophy
Department of Human Nutrition
Brian Lindshield
Fortified blended foods (FBFs), in particular, corn-soybean blend (CSB), are food aid commodities widely used in infant and young children supplementary feeding programs. A United States Agency for International Development (USAID) Food Aid Quality Review report recommended developing novel FBFs using local alternative commodities such as sorghum and improving the nutritional quality of FBFs using extrusion processing. Extruded sorghum-cowpea, sorghum-soy and corn-soy FBFs were developed and compared with the non-extruded FBFs corn-soy blend 13 (CSB13) and corn-soy blend plus (CSB+) using the in-vitro digestion/Caco-2 cell model. Dry FBFs’ iron and vitamin A content ranged from 8.0 to 31.8 mg/100g and 0.54 to 1.67 mg/100g, respectively. Following in-vitro digestion, bioavailable iron and vitamin A levels were determined by measuring Caco-2 cell ferritin and vitamin A levels in response to 12-hour and 4-hour treatments, respectively, with aqueous fractions collected from digested FBFs. Most extruded FBFs’ aqueous fraction iron levels were 2- to 7-fold higher (p<0.05) than CSB13 and CSB+. However, Caco-2 cell ferritin and vitamin A levels were not significantly different among FBFs. These results suggest that consumption of newly developed extruded sorghum-cowpea, sorghum-soy and corn-soy FBFs will result in bioavailable iron and vitamin A levels comparable to traditional non-extruded CSB13 and CSB+. Thus, extruded sorghum-cowpea FBF may be a suitable alternative to corn-soybean based FBFs. Saw palmetto supplements are one of the most commonly consumed products by men with prostate cancer and/or benign prostatic hyperplasia (BPH). Some studies have found significant improvements in BPH with saw palmetto supplementation, whereas others found no benefits. The variation in the efficacy in these trials may be a result of differences in the putative active components, fatty acids and phytosterols, of the saw palmetto supplements. We quantified fatty acids and phytosterols in 20 commercially available liquid, powder, dried berry, and tincture saw palmetto supplements. Liquid saw palmetto supplements contained significantly higher (p<0.05) concentrations of total fatty acids (908.5 mg/g), individual fatty acids, total phytosterols (2.04 mg/g), and individual phytosterols, than the other supplement categories. Our findings suggest that liquid saw palmetto supplements may be the best choice for individuals who want to take a saw palmetto supplement.

APA, Harvard, Vancouver, ISO, and other styles

24

Mora, Katherine. "Diet and Depression: A Secondary Analysis from NHANES 1999-2002." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/194112.

Full text

Abstract:

This Ph.D. dissertation presents results that shed light on whether there is an association between dietary intake and depressive disorder, feelings of sadness, or thoughts of death. This question is investigated in the context of a secondary data analysis using cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) 1999-2002. Subjects in this study were identified as a subpopulation of the NHANES survey that completed the Composite International Diagnostic Interview questionnaire for major depression. The presence of depression may lead to a decline in dietary intake and nutritional status. Conversely, poor dietary intake may have a role in the etiology of depression. Specifically, depression is associated with lower plasma, erythrocyte, phospholipid, and adipose tissue omega-3 fatty acids. Little is known about the comprehensive dietary intake of those with depression or depressive symptoms. Initially, comparisons of the dietary profile between those with and without depression or depressive symptoms were investigated. Secondly, analysis was done to determine the relationship between dietary omega-3 fatty acids and depression or depressive symptoms. Lastly, to clarify the relationship between diet and depression, misreporting of dietary energy intake was evaluated.No significant differences in the dietary profile or nutritional biochemistries were found between the altered mood and normal mood groups. No significant differences were found in dietary omega-3 fatty acids between the depressed and non-depressed groups, even after adjusting for confounding variables. Misreporting of energy intake was not significantly associated with altered mood status and remained non-significant after adjusting for confounding variables. In both groups, a significant decreasing trend in the ratio of energy intake to estimated basal metabolic rate (EI:BMRest) was found as body mass index increased.Based on dietary intake alone, the relationship between depression and specific nutrients may not be apparent. Dietary intake among those with depression and depressive symptoms appears to be adequate, but adequacy may not be sufficient as a route for prevention or management of depression. Further investigation of diet and depression ought to measure diet, including nutrition supplements, and biochemical levels of nutrients from a broader age range of adults and children and those with comorbid illnesses.

APA, Harvard, Vancouver, ISO, and other styles

25

Gigliotti, Joseph Christopher. "Determination of the nutritional value, protein quality and safety of krill protein concentrate isolated using an isolelectric solubilization/precipitation technique." Morgantown, W. Va. : [West Virginia University Libraries], 2007. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=5471.

Full text

Abstract:

Thesis (M.S.)--West Virginia University, 2007.
Title from document title page. Document formatted into pages; contains vii, 44 p. : ill. Includes abstract. Includes bibliographical references (p. 30-33).

APA, Harvard, Vancouver, ISO, and other styles

26

Orwar, Owe. "Laser-based ultra-trace analysis in liquid chromatography determination of neuroactive amino acids and peptides /." Göteborg : Dept. of Analytical and Marine Chemistry, University of Göteborg, 1994. http://catalog.hathitrust.org/api/volumes/oclc/39775021.html.

Full text

APA, Harvard, Vancouver, ISO, and other styles

27

Dasgupta, Sunanda [Verfasser], Peter [Gutachter] Ay, and Christian [Gutachter] Stollberg. "Metastable zone determination and nucleation kinetics during melt crystallization of poly-unsaturated fatty acids / Sunanda Dasgupta ; Gutachter: Peter Ay, Christian Stollberg." Cottbus : BTU Cottbus - Senftenberg, 2018. http://d-nb.info/1151520810/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Lam, Chi-chung, and 林子聰. "Nuclear magnetic resonance spectroscopy as an analytical tool in the structural analysis of triacylglycerols." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B31233636.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Crossan, Anthony Kevin. "Solid state analysis of chlorhexidine and fatty acids and their pharmaceutical applications in antimicrobial polymer systems." Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.705897.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

招志明 and Chi-ming Lawrence Chiu. "Possible mechanisms of arachidonic and eicosapentaenoic acids on humanleukemic cell proliferation and apoptosis by flow cytometric analysis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1998. http://hub.hku.hk/bib/B31236741.

Full text

APA, Harvard, Vancouver, ISO, and other styles

31

Chiu, Chi-ming Lawrence. "Possible mechanisms of arachidonic and eicosapentaenoic acids on human leukemic cell proliferation and apoptosis by flow cytometric analysis /." Hong Kong : University of Hong Kong, 1998. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19737907.

Full text

APA, Harvard, Vancouver, ISO, and other styles

32

Williams, Anest. "Lipid profilling of polyunsaturated fatty acid - treated mouse brain and plasma. Investigation into polyunsaturated fatty acid (PUFA)-induced neuroprotection." Thesis, University of Bradford, 2010. http://hdl.handle.net/10454/4414.

Full text

Abstract:

Pre-treatment with polyunsaturated fatty acids or bioactive lipid mediators has been shown to reduce neuronal injury in rodent models of focal ischaemia, but the molecular mechanisms underlying this neuroprotection are unclear. In this study, we aimed to investigate whether systemic administration of alpha linolenic acid (ALA) leads to changes in the profile of mouse brain phospholipid and bioactive lipid mediators in both mouse brain and plasma within the previously determined neuroprotection time window. Mass spectrometry (MS) and tandem mass spectrometry (MS/MS) allowed us to detect and identify 47 phospholipids in mouse cerebral cortex, including several phospholipid species not previously reported in brain lipidomic studies. These included a phosphatidylethanolamine species with m/z 720 that has been associated with retinal stem cells. No widespread changes in cerebral cortex phospholipid composition were observed following intravenous ALA. Several significant changes in lipid mediators (P<0.05 with two-way ANOVA and post hoc Dunnett's t test) were detected in ALA-treated animals compared to untreated and vehicle-injected animals. Many of the affected lipid mediators are ligands for prostanoid receptors which have been demonstrated to play a role in the development of brain injury following cerebral ischaemia, implying that changes in bioactive lipid mediators or modulation of prostanoid receptors may occur following ALA pre-treatment in mice. This study illustrates the potential of advanced lipidomic analysis as a novel tool for neurochemists.

APA, Harvard, Vancouver, ISO, and other styles

33

Tappenden, Kelly Anne. "Short-chain fatty acids enhance intestinal adaptation in rats receiving total parenteral nutrition, a multi-organ analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21646.pdf.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Alghamdi, Fatmah. "ANALYSIS OF THE OMEGA-3 FATTY ACIDS CONTENT IN COMMERCIAL OMEGA-3 SUPPLEMENTS IN ARAB GULF COUNTRIES." OpenSIUC, 2019. https://opensiuc.lib.siu.edu/theses/2571.

Full text

Abstract:

The consumption of omega-3 fatty acids has increased over the past years for multiple reported health benefits. The omega-3 fatty acids of particular interest are eicosatetraenoic acid (C20:5n3; EPA) and docosahexaenoic acid (C22:6n3; DHA). High quality supplements are essential for safe intake. Studies from different countries including the United States and South Africa showed discrepancies between measured versus the claimed content of EPA and/or DHA in omega-3 supplements sold in Arab Gulf Countries. Therefore, the objective of this study was to analyze and compare the EPA and DHA content of omega-3 supplements with the contents claimed on the product label. Thirty-one commercial supplements purchased from stores in 3 different countries (Saudi Arabia, Kuwait, and Bahrain) had their fatty acid composition and content were analyzed using Gas- Chromatograph with a 100-m SP-2560 fused silica capillary column. The range of measured EPA was 5.09 mg to 469.63 mg per capsule and for DHA was 10.47 to 357.26 mg per capsule. The percentage of the stated label amount for EPA and DHA ranged from 6.5 to 138.6% and 10.9 to 126.3%, respectively. Using the U.S. Food and Drug Administration (FDA) labeling requirements where a supplement must contain at least 80% of the stated label amount of each component listed, only 43.8% of the supplements were compliant for EPA and 40.6% were compliant for DHA. Additionally, only 21.9% of the measured EPA and DHA fall within the 10% of the stated label amount. These results demonstrate the wide variability between the stated label amounts of EPA and DHA in omega-3 supplements sold in Arab Gulf Countries and the need for governmental agencies to perform testing to ensure compliance.

APA, Harvard, Vancouver, ISO, and other styles

35

Nolte, Noreen Kathleen. "Protection of the long chain N-3 polyunsaturated fatty acids in hake head flour against oxidation." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/49781.

Full text

APA, Harvard, Vancouver, ISO, and other styles

36

Zhang, Daiyuan Pirtle Robert M. "Expression analysis of the fatty acid desaturase 2-4 and 2-3 genes from Gossypium hirsutum in transformed yeast cells and transgenic Arabidopsis plants." [Denton, Tex.] : University of North Texas, 2008. http://digital.library.unt.edu/permalink/meta-dc-9002.

Full text

APA, Harvard, Vancouver, ISO, and other styles

37

Kongcharoensuntorn, Wisatre. "Isolation and analysis of cotton genomic clones encompassing a fatty acid desaturase (FAD2) gene." Thesis, University of North Texas, 2001. https://digital.library.unt.edu/ark:/67531/metadc2796/.

Full text

Abstract:

Polyunsaturated fatty acids are major structural components of plant chloroplast and endoplasmic reticulum membranes. Two fatty acid desaturases (designated FAD2 and FAD3) desaturate 75% of the fatty acids in the endoplasmic reticulum. The w -6 fatty acid desaturase (FAD2) may be responsible for cold acclimation response, since polyunsaturated phospholipids are important in helping maintain plant viability at lowered temperatures. To study regulation of FAD2 gene expression in cotton, a FAD2 gene was isolated from two genomic libraries using an Arabidopsis FAD2 hybridization probe and a cotton FAD2 5¢ -flanking region gene-specific probe, respectively. A cotton FAD2 gene was found to be in two overlapping genomic clones by physical mapping and DNA sequencing. The cloned DNA fragments are identical in size to cotton FAD2 genomic DNA fragments shown by genomic blot hybridization. The cotton FAD2 coding region has 1,155 bp with no introns and would encode a putative polypeptide of 384 amino acids. The cotton FAD2 enzyme has a high identity of 75% with other plant FAD2 enzymes. The enzyme has three histidine-rich motifs that are conserved in all plant membrane desaturases. These histidine boxes may be the iron-binding domains for reduction of oxygen during desaturation. To confirm that this FAD2 enzyme is functional, a plasmid construct containing the cotton FAD2 coding region was transformed into Saccharomyces cerevisiae. The transformed yeast cells were able to catalyze the conversion of oleic acid (C18:1) into linoleic acid (C18:2). The FAD2 gene contains an intron of 2,967 bp in its 5¢ -flanking region, 11 bp upstream from the initiation codon. The intron could be essential for transcriptional regulation of FAD2 gene expression. Several putative promoter elements occur in the 5¢ -flanking region of this gene. A potential TATA basal promoter element occurs at 41 bp upstream from the cap site. Two presumptive helix-loop-helix (bHLH) motifs that may be seed-specific promoter elements are located at 109 bp and 135 bp upstream from the potential cap site.

APA, Harvard, Vancouver, ISO, and other styles

38

Brian, King Himm Mo. "Biochemical analysis and genetic engineering of oleaginous fungi for the production of eicosapentaenoic acid and free fatty acid derivatives." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263714.

Full text

APA, Harvard, Vancouver, ISO, and other styles

39

Zhang, Qingyu, Rui Yu, Daoyang Sun, Mahbubur Rahman, Lihang Xie, Jiayuan Hu, Lixia He, Aruna Kilaru, Lixin Niu, and Yanlong Zhang. "Comparative Transcriptome Analysis Reveals an Efficient Mechanism for Α-Linolenic Acid Synthesis in Tree Peony Seeds." Digital Commons @ East Tennessee State University, 2018. https://dc.etsu.edu/etsu-works/4740.

Full text

Abstract:

Tree peony (Paeonia section Moutan DC.) species are woody oil crops with high unsaturated fatty acid content, including α-linolenic acid (ALA/18:3; >40% of the total fatty acid). Comparative transcriptome analyses were carried out to uncover the underlying mechanisms responsible for high and low ALA content in the developing seeds of P. rockii and P. lutea, respectively. Expression analysis of acyl lipid metabolism genes revealed upregulation of select genes involved in plastidial fatty acid synthesis, acyl editing, desaturation, and triacylglycerol assembly in seeds of P. rockiirelative to P. lutea. Also, in association with ALA content in seeds, transcript levels for fatty acid desaturases (SAD, FAD2, and FAD3), which encode enzymes necessary for polyunsaturated fatty acid synthesis, were higher in P. rockii compared to P. lutea. Furthermore, the overexpression of PrFAD2 and PrFAD3 in Arabidopsis increased linoleic and ALA content, respectively, and modulated the final ratio 18:2/18:3 in the seed oil. In conclusion, we identified the key steps and validated the necessary desaturases that contribute to efficient ALA synthesis in a woody oil crop. Together, these results will aid to increase essential fatty acid content in seeds of tree peonies and other crops of agronomic interest.

APA, Harvard, Vancouver, ISO, and other styles

40

Armstrong, Sharyn G., of Western Sydney Hawkesbury University, and Faculty of Science and Technology. "Chemical analysis of nutritionally important components in temperate Australian fish." THESIS_FST_XXX_Armstrong_S.xml, 1992. http://handle.uws.edu.au:8081/1959.7/505.

Full text

Abstract:

The lipid composition of five species of marine finfish from temperate Australian waters was determined. Claims that the lipids of Australian fish contain high levels of omega-6 fatty acids and arachidonic acid (AA) were investigated. Individual fish were analysed from samples collected at three locations and two seasons, and they were found to have fatty acid compositions of similar nutritional value to those from northern hemisphere temperate waters. Levels of AA, eicosapentaenoic acid and docosahexaenoic acid were also found to be comparable. The variability in fatty acid compositions was greater between samples taken from different locations than from different seasons. Lipid contents and compositions were found to exhibit some species-characteristic nature, indicating a need for accurate species identification. A high-performance liquid chromatographic (HPLC) method for fish identification was developed, which was successful. The application of HPLC to processed fish was investigated and it was found to be suitable for gamma-irradiated and infrared dried fish, but not for those that had been smoked or microwave cooked.
Doctor of Philosophy (PhD)

APA, Harvard, Vancouver, ISO, and other styles

41

Du, Fuying, and 杜富滢. "Microchip-capillary electrophoresis devices with dual-electrode detectors for determination of polyphenols, amino acids andmetabolites in wine and biofluids." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48521693.

Full text

Abstract:

The electrochemical detector provides a promising detection mode for capillary electrophoresis (CE) due to its excellent sensitivity, good portability, high selectivity, easy miniaturization, low capital and running cost. To widen its scope for determining trace analytes in complex samples, three dual-electrode detectors were fabricated to enable the determination of electro-inactive analytes, to assess co-eluted peaks and to give a large enhancement of the detection sensitivity by modifying electrode surface using multi-walled carbon nanotubes (MWNTs). To determine trace non-electroactive amino acids present in human tears, a serial dual-electrode detector was developed using an upstream on-capillary Pt film electrode to oxidize bromide to bromine at +1.0 V and a downstream Pt disk electrode to detect the residual bromine at +0.2 V after their reaction with amino acids eluted out from the separation capillary. The bromide reagent was introduced after CE separation by a newly designed coaxial post-column reactor fabricated onto the PMMA chip. Using optimized CE buffer containing 20 mM borate, 20 mM SDS at pH 9.8, L-glutamine, L-alanine and taurine were baseline separated with detection limits ranging from 0.56-0.65 μM and a working range of 2-200 μM for L-glutamine and of 2-300 μM for both L-alanine and taurine. Method reliability was established by close to 100% recoveries for spiked amino acids and good agreement between the measured and the literature reported amino acid concentrations in tears. For the determination of polyphenols in wine, a microchip-CE device was fabricated with a dual-opposite carbon fiber microelectrode operated in a parallel mode to assess peak purity. Under optimized conditions, (+)-catechin, trans-resveratrol, quercetin, (-)-epicatechin and gallic acid were baseline separated within 16 min with detection limits ranging from 0.031- 0.21 mg/L and repeatability of 2.0-3.3 % (n=5). The use of an opposite dual-electrode enables the simultaneous determination of peaks and measurement of their current ratios at +0.8 V and +1.0 V vs Ag/AgCl. The capability of using current ratio to identify the presence of co-migrating impurities was demonstrated in a mixed standard solution with overlapping (+)-catechin and (-)-epicatechin peaks and in a commercial red wine with interfering impurities. Matching of both the migration time and the current ratio reduce false positive and validate polyphenol quantitation in red wine. Lastly, a dual-opposite MWNTs modified carbon fiber microelectrode (CFME) was developed to determine the biomarkers (4-nitrophenol, 4-nitrophenyl-glucuronide and 4-nitrophenyl-sulfate) needed to assess exposure to methyl parathion. Use of the MWNTs modified CFME showed a much higher sensitivity than bare CFME, with a detection limit of 0.46 μM for 4-nitrophenol. Baseline separation of all three biomarkers was obtained within 31 min by a 45 cm long capillary under 12 kV in a 20 mM phosphate buffer at pH 7.0. The method developed was successfully utilized to determine low levels of biomarkers in human urine without using complex pretreatment steps and delivered recoveries ranging from 95.3 - 97.3% and RSDs within 5.8% (n=3). Using a parallel dual-electrode detector was shown to deliver reliable results with matching current ratios and comparable migration time to those obtained from biomarker standards.
published_or_final_version
Chemistry
Doctoral
Doctor of Philosophy

APA, Harvard, Vancouver, ISO, and other styles

42

Zhang, Daiyuan. "Expression analysis of the fatty acid desaturase 2-4 and 2-3 genes from Gossypium hirsutum in transformed yeast cells and transgenic Arabidopsis plants." Thesis, University of North Texas, 2008. https://digital.library.unt.edu/ark:/67531/metadc9002/.

Full text

Abstract:

Fatty acid desaturase 2 (FAD2) enzymes are phosphatidylcholine desaturases occurring as integral membrane proteins in the endoplasmic reticulum membrane and convert monounsaturated oleic acid into polyunsaturated linoleic acid. The major objective of this research was to study the expression and function of two cotton FAD2 genes (the FAD2-3 and FAD2-4 genes) and their possible role in plant sensitivity to environmental stress, since plants may increase the polyunsaturated phospholipids in membranes under environmental stress events, such as low temperature and osmotic stress. Two FAD2 cDNA clones corresponding to the two FAD2 genes have been isolated from a cotton cDNA library, indicating both genes are truly expressed in cotton. Model yeast cells transformed with two cotton FAD2 genes were used to study the chilling sensitivity, ethanol tolerance, and growth rate of yeast cells. The expression patterns of the two FAD2 genes were analyzed by reverse transcription polymerase chain reactions (RT-PCR) and Western blot analyses in cotton plants under different treatment conditions. The coding regions of both FAD2 genes were inserted downstream from the CaMV 35S promoter in the pMDC gateway binary vector system. Five different FAD2/pMDC constructs were transformed into the Arabidopsis fad2 knockout mutant background, and multiple potential transgenic Arabidopsis plant lines harboring the cotton FAD2 genes were generated. The cotton FAD2 genes were amplified by the polymerase chain reaction (PCR) from the genomic DNAs isolated from the transgenic Arabidopsis T1 plant lines. Complementation of the putative transgenic Arabidopsis plants with the two cotton FAD2 genes was demonstrated by gas chromatography analyses of the fatty acid profiles of leaf tissues. The cellular localization of cotton FAD2-4 polypeptides with N-terminal green fluorescence protein (GFP) was visualized by confocal fluorescence microscopy. The phenotype of transgenic Arabidopsis plants transformed with the cotton FAD2-4 gene was compared to Arabidopsis knockout fad2 mutant plants and wild type Arabidopsis plants regarding their sensitivity to low temperature, and the size and height of the plants.

APA, Harvard, Vancouver, ISO, and other styles

43

Arriola, Ortiz Aline. "On the dynamics and selective transport of fatty acids and organochlorines in lactating grey seals (Halichoerus grypus)." Thesis, St Andrews, 2010. http://hdl.handle.net/10023/895.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Mahdiani, Maryam [Verfasser], and Leane [Gutachter] Lehmann. "Quantitative analysis of fatty acids, cholesterol and oxidation products thereof in human breast adipose tissues / Maryam Mahdiani ; Gutachter: Leane Lehmann." Würzburg : Universität Würzburg, 2017. http://d-nb.info/1149510366/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Benkestock, Kurt. "Electrospray Ionization Mass Spectrometry for Determination of Noncovalent Interactions in Drug Discovery." Doctoral thesis, KTH, Analytisk kemi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4730.

Full text

Abstract:

Noncovalent interactions are involved in many biological processes in which biomolecules bind specifically and reversibly to a partner. Often, proteins do not have a biological activity without the presence of a partner, a ligand. Biological signals are produced when proteins interact with other proteins, peptides, oligonucleotides, nucleic acids, lipids, metal ions, polysaccharides or small organic molecules. Some key steps in the drug discovery process are based on noncovalent interactions. We have focused our research on the steps involving ligand screening, competitive binding and ‘off-target’ binding. The first paper in this thesis investigated the complicated electrospray ionization process with regards to noncovalent complexes. We have proposed a model that may explain how the equilibrium between a protein and ligand changes during the droplet evaporation/ionization process. The second paper describes an evaluation of an automated chip-based nano-ESI platform for ligand screening. The technique was compared with a previously reported method based on nuclear magnetic resonance (NMR), and excellent correlation was obtained between the results obtained with the two methods. As a general conclusion we believe that the automated nano-ESI/MS should have a great potential to serve as a complementary screening method to conventional HTS. Alternatively, it could be used as a first screening method in an early phase of drug development programs when only small amounts of purified targets are available. In the third article, the advantage of using on-line microdialysis as a tool for enhanced resolution and sensitivity during detection of noncovalent interactions and competitive binding studies by ESI-MS was demonstrated. The microdialysis device was improved and a new approach for competitive binding studies was developed. The last article in the thesis reports studies of noncovalent interactions by means of nanoelectrospray ionization mass spectrometry (nanoESI-MS) for determination of the specific binding of selected drug candidates to HSA. Two drug candidates and two known binders to HSA were analyzed using a competitive approach. The drugs were incubated with the target protein followed by addition of site-specific probes, one at a time. The drug candidates showed predominant affinity to site I (warfarin site). Naproxen and glyburide showed affinity to both sites I and II.
QC 20100705

APA, Harvard, Vancouver, ISO, and other styles

46

Wen, Miao. "Chemical analysis and biosynthesis of secondary alcohols in plant cuticular waxes." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/4304.

Full text

Abstract:

The biosynthesis of wax components containing secondary functional groups was investigated in the current study. Two fundamentally different pathways were proposed to introduce the secondary functional groups. One pathway involves hydroxylation of elongated substrates. Wax components characterized by two functional groups located on or near the centre of the carbon chain, nonacosane-14,15-diol, -14,16-diol and -13,15-diol as well as corresponding ketols were identified for the first time in Arabidopsis stem wax. The alkanediols and ketols were dominated by the C-14,15 isomers. The absence of alkanediols and ketols in Arabidopsis mah1 mutants that are deficient in secondary alcohol biosynthesis confirmed the biosynthetic relationship between secondary alcohols and alkanediols/ketols (Chapter 3). In pea (Pisum sativum) leaf wax, two novel compound classes were identified as primary/secondary alcohols dominated by octacosane-1,14-diol and secondary/secondary alkanediols hentriacontane-9,16-diol, -8,15-diol and -10,17-diol. Co-localization of the secondary/secondary alkanediols and hentriacontan-15-ol and -16-ol pointed to a biosynthetic relationship (Chapter 4). The diverse structures of compounds identified in the current study suggested that hydroxylases can use substrates other than alkanes. The predominance of isomers within homologues indicated a regiospecificity of the hydroxylases involved in wax biosynthesis. In addition to hydroxylation, secondary functional groups could also be introduced through elongation of carbon chains. Homologous series of 5-hydroxyaldehydes (C₂₄ and C₂₆-C₃₆) and 1,5-alkanediols (C₂₈-C₃₈) were identified in yew (Taxus baccata) needle wax. The relative position of both functional groups suggested that these two compound classes are biosynthetically related and their secondary functional groups are introduced during elongation (Chapter 5). The results of incubation of ¹⁴C-labeled malonyl-CoA and acyl-CoAs with different chain lengths in the presence of California poppy (Eschscholzia californica) microsomes provided the first evidence to support the elongation hypothesis. The results indicated that a carbonyl group rather than a hydroxyl group is introduced during elongation. To provide molecular tools for further investigations of the hypothetical pathway, three full length cDNAs encoding putative KCSs were cloned and one of them, PKCSI, was functionally characterized.

APA, Harvard, Vancouver, ISO, and other styles

47

Friesen, Erin. "Use of alternative feed ingredients and the effects on growth and flesh quality of Atlantic salmon (Salmo salar) and sablefish (Anoplopoma fimbria)." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/2610.

Full text

Abstract:

Aquaculture feeds, traditionally composed mainly of fishmeal and fish oil, currently represent the largest cost to fish farmers. With aquaculture growing at an average of 8.8% per year and limited supply of fishmeal and fish oil, suitable alternatives must be found. In addition to increasing sustainability and lowering production costs, the use of plant and/or animal ingredients has the potential to lower flesh levels of persistent organic pollutants (POPs) such as polychlorinated biphenyls. Fish oil and to a lesser extent fishmeal, are considered to be the largest source POPs in farmed fish. Using alternative feed ingredients however, can compromise fish growth and the flesh quality of the final product. Lipid sources including flaxseed oil, canola oil, poultry fat and the protein sources canola protein concentrate, soy protein concentrate and poultry by-product meal were examined as alternatives to fish oil and fishmeal in one on-farm field study and one laboratory feeding trial with Atlantic salmon (Salmon salar) and two laboratory feeding trials conducted on sablefish (Anoplopoma fimbria), a relatively new marine aquaculture species. The nutritive value of the alternative ingredients was assessed on the basis of fish growth performance, proximate composition, fatty acid composition and apparent digestibility coefficients. Sensory attributes were evaluated in the sablefish studies while flesh POP levels were determined in both species. The use of alternative dietary lipids showed no negative effects on fish performance. However replacement of fishmeal with plant proteins in some cases, negatively affected fish growth. Flesh levels of persistent organic pollutants were significantly decreased (p<0.05) with the use of alternative dietary lipids, and flesh levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were also depressed. Activated carbon treated anchovy oil and finishing diets were examined in the Atlantic salmon laboratory feeding trial and were effective at lowering flesh POP levels while providing high levels of EPA and DHA. The use of alternative feed ingredients will soon be inevitable in aquaculture feeds. The current research shows alternative lipids and proteins can be incorporated successfully in sablefish and Atlantic salmon feeds with minimal effects on fish growth and quality.

APA, Harvard, Vancouver, ISO, and other styles

48

Lau, Clara Sueling. "Formulation and Physical, Chemical and Sensory Analysis of a Novel Flaxseed-enriched Milk-based Beverage to Deliver Omega-3 Fatty Acids." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/29396.

Full text

Abstract:

An increased interest in functional beverages is occurring, and omega-3 fatty acids (FA) are one of the most commonly sought ingredients to fortify such beverages. Omega-3 FA produce beneficial health effects, likely due to their anti-inflammatory properties. The majority of current omega-3 FA-fortified products include marine-derived omega-3 FA sources, often producing undesired flavors due to lipid oxidation. Little research regarding incorporation of alpha-linolenic acid in functional beverage formulation has been conducted. Alpha-linolenic acid is less susceptible to oxidation and may be a candidate to deliver omega-3 FA into the diet via functional products. Flaxseed is the richest plant source for alpha-linolenic acid; consumption may increase omega-3 FA intake and lower the omega-6:omega3 FA ratio, thereby, attenuating inflammation. Finely ground flaxseed was, therefore, incorporated into a chocolate milk foundation ("flaxmilk") to increase dietary omega-3 FA. An untrained consumer panel tasted and rated flaxmilk's palatability using a 9-point hedonic scale. A score of "6.0" ("like slightly") was targeted. A mean hedonic score of 6.35 was achieved, surpassing the targeted score and indicating an acceptable product. Sensory and analytical analyses of flaxmilk were conducted and compared to standard chocolate milk. Flaxmilk was significantly different in most physical, chemical and sensory characteristics compared to chocolate milk. A reduction in the omega-6:omega-3 FA ratio may attenuate inflammation; inflammation has been linked to osteoporosis. Thus, a secondary analysis of data collected from 202 women was conducted to estimate the dietary omega-6:omega-3 FA ratio and examine relationships between the omega-6:omega-3 FA ratio and total body and site-specific bone mineral density (BMD). The omega-6:omega-3 FA ratio had no appreciable association with any measure of BMD in the overall sample of women or in younger or older subsamples of women. In summary, consumers found flaxmilk to be an acceptable product, despite sensory and compositional differences compared to chocolate milk. The relationship between the omega-6:omega-3 FA ratio and BMD remains unclear.
Ph. D.

APA, Harvard, Vancouver, ISO, and other styles

49

董豪珊 and Ho-shan Tung. "Development of analytical methodologies for the determination of metals and organic acids in environmental and traditional Chinesemedicine studies by capillary electrophoresis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31242340.

Full text

APA, Harvard, Vancouver, ISO, and other styles

50

Lau, Chun-pong, and 劉振邦. "Applications of stoichiometry, stable isotopes, and fatty acids for elucidating the relative importance of allochthonous and autochthonousresources in Hong Kong streams." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40040185.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Fatty acids (Analysis; Determination)'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles