Three separate experiments were conducted to investigate the effects of heat treatment on meat heme and nonheme iron bioavailability in anemic rats. Male weanling Sprague-Drawley rats were first made anemic, then subsequently fed with experimental diets. In the first experiment, dietary iron sources were raw or autoclaved meat mixed with ferrous sulfate to give the ratios of iron from meat and ferrous sulfate equal to 100:0, 75:25, 50:50, 25:75, and 0:100 respectively. For the second experiment, the dietary iron sources were raw or autoclaved meat mixed with bovine hemoglobin (HB) to give dietary iron ratios as described for experiment 1. For experiment 3, dietary iron sources were boiled meat and baked meat. Known amounts of the experimental diets were fed the anemic rats for a 10-day repletion period. Body weight, hemoglobin concentration and hematocrit were determined before and after the repletion period. The animals were then sacrificed and the liver iron content was measured, as was the iron content of the feces from the last 7 days on test of each rat. In vitro digestion was done to determine the amount of soluble iron in the diets. Heat treatment increased the bioavailability of iron from hemoglobin from 23% to 30%. The effect of cooking on the bioavailability of iron from meat and ferrous sulfate were negligible. The efficiencies of conversion were 35, 37, 36 and 37 for raw meat, autoclaved meat, boiled meat and baked meat, respectively. Ferrous sulfate gave the highest bioavailability in anemic rats (65%). As the dietary proportion of iron from ferrous sulfate increased, the dietary iron bioavailability increased proportionally. Iron bioavailability decreased as the proportion of dietary iron from hemoglobin (HB) increased. Meat did not increase the bioavailability of iron from either ferrous sulfate or hemoglobin. Heat treatment decreased the heme iron content in the diets but did not affect the amount of soluble iron. Soluble iron content increased as the dietary proportion of iron from ferrous sulfate or hemoglobin (HB) increased. There was no correlation between the iron. bioavailability in rat and the soluble iron content determined by in vitro digestion.

La biodisponibilité d'un composé minéral dépend de sa solubilité in vivo contrôlée par ses propriétés physicochimiques. Cependant, les caractéristiques physicochimiques qui influencent la solubilité et la biodisponibilité des produits utilisés en nutrition animale ne sont pas clairement connues. L'oxyde de zinc (ZnO) est un additif alimentaire couramment utilisé pour satisfaire le besoin en zinc (Zn) des animaux monogastriques. L'objectif de ce projet était de caractériser plusieurs types de ZnO utilisés en nutrition animale pour mieux appréhender leur devenir dans le tractus digestif et leur biodisponibilité. Les différentes sources de ZnO ont des propriétés physicochimiques variables qui influencent leurs cinétiques de dissolution. Une quarantaine d'échantillons de ZnO collectés à travers le monde auprès d'industries de la nutrition animale ont été caractérisés en termes de densité, densité tassée, taille de particules, forme, aire spécifique et cinétiques de dissolution. Une analyse en composantes principales (ACP) a été réalisée pour identifier les caractéristiques les plus pertinentes et classer les échantillons par familles. La nature des paramètres les plus pertinents suggère un mécanisme en deux étapes : dissolution de ZnO en ions Zn2+ à la surface des particules, suivie d'une diffusion vers la solution. La vitesse de dissolution détermine probablement le devenir de ZnO dans le tractus gastro-intestinal et pourrait donc expliquer les différences de performances. Une étude in vivo de produits représentatifs de chaque famille a permis de déterminer les effets des caractéristiques physicochimiques sur la biodisponibilité. Une étude dose-réponse a été réalisée sur des poulets Cobb en croissance (8 à 23 jours d'âge) soumis à un régime de base contenant 23 ppm de zinc ou à 14 régimes supplémentés à raison de 6 ou 12 ppm de ZnO (6 sources différentes) ou de sulfate de Zn. La teneur en zinc du tibia a été utilisée pour estimer la biodisponibilité relative des différentes sources de ZnO par rapport au sulfate de Zn utilisé comme référence (100%). La biodisponibilité des différentes sources variait entre 49% à 160%. La taille des agrégats et la surface spécifique expliquent une large part de la variabilité sur la biodisponibilité. En conclusion, les propriétés physicochimiques de ZnO permettent d'expliquer partiellement la variabilité observée des biodisponibilités du zinc car la complexité des phénomènes physiologiques rend difficile une telle prédiction / The bioavailability of a trace mineral source is related to its in vivo solubility, which in turn is determined by its physicochemical properties. It is still not clear which characteristics are more relevant in affecting solubility and bioavailability of feed compounds. Zinc Oxide (ZnO) is a common feed additive used to supplement zinc in the diet of monogastrics animals. However, different sources have shown different responses in animal bioavailability. This project aims to characterize different feed grade ZnO to better clarify their fate in the digestive tract and explain differences in bioavailability. It was hypothesized that the different sources of feed grade ZnO have various physicochemical properties that lead to distinct dissolution kinetics. Over 40 samples of ZnO have been collected from the feed industry worldwide. Samples were analyzed for density, tapped density, particle size, shape, specific area and dissolution kinetics. A principal component analysis (PCA) was performed to define the most relevant characteristics and categorize the samples into groups. The results showed that there is not only one variable influencing the kinetics of dissolution. It suggests a dissolution mechanism in 2 steps, in which there is the dissolution of ZnO into Zn ions in the surface of the particle, followed by a diffusion to the bulk solution. The speed of dissolution can determine the fate of zinc oxide products in the gastrointestinal tract and therefore may explain the different results in animal performance. Representative products from each family were selected for an in vivo trial to measure the effect of their characteristics on the zinc bioavailability. Male Cobb broilers were used in a dose-response experiment from 8 to 23 days of age. Treatments consisted of a basal diet with 23 ppm of zinc and 14 diets supplemented with 6 or 12 ppm of Zn in the form of different oxides or sulfate. Bone zinc was used to determine zinc bioavailability. The bioavailability of the different sources varied from 49 to 160% considering zinc sulfate as the reference. Aggregate size and specific surface area explain a large part of the variability observed on values of bioavailability. In conclusion, physicochemical properties of ZnO can partly explain the variability observed in terms of Zn biological value. However, the complexity of physiological processes makes difficult the prediction of Zn bioavailability based only on these characteristics

Abstract not available

This thesis describes in vitro and in vivo evaluation of a gastric retention formulation (GRF) developed at Oregon State University. The formulation was prepared from xanthan gum and locust bean gum as gelling agents and other formulation ingredients were added, then it was originally vacuum oven dried. The effect of freeze drying on GRF was studied in this research. Freeze dried GRF were evaluated for dissolution and drug release properties using hydrochlorothiazide as a model drug. The effect of storage of GRF inside hard gelatin capsules on rate of swelling of the capsule shell and release of GRF was also studied. Storage for up to 12 months had no effect on capsule shell swelling and release of GRF. Gastric residence time, pharmacokinetics and bioavailability of hydrochlorothiazide, a drug that has an absorption window limited to the upper small intestine, from two different sizes of gastric retention formulations (GRF) were evaluated in 12 healthy volunteers in both fed and fasted states, and compared to immediate release tablets. Extent of bioavailability of drug from the larger formulation in this study was comparable to IR tablets in both fed and fasted states. Deconvolved input functions data suggest that the GRF stayed in the stomach providing sustained drug input for 12-28 hours. Initial blood pressure lowering and side effects of hydrochlorothiazide from a gastric retention formulation were evaluated and compared to immediate release tablets in 10 subjects with stage I hypertension. Gastric retention formulations produced an average reduction in systolic blood pressure 3 mm Hg lower than IR tablets regardless of sequence of administration. GRF also produced less blood pressure fluctuation in most subjects than IR tablets. Most subjects reported fewer and less severe side effects with GRF than IR tablets. / Graduation date: 2004

Graduation date: 1996

Seed coat biochemistry and colour are highly variable in common bean (Phaseolus vulgaris) (syn. dry bean). Genetic studies of dry bean seed coat chemistry and colour have important implications in breeding efforts for improving nutrition and seed quality for consumer acceptance. The results of this thesis detail the phenotypic and genotypic characterization of seed coat post harvest darkening (PHD) in parents and progeny of crosses among them as well as the phenotypic characterization of seed coat condensed tannin (CT) accumulation in five genotypes of bean.<p> Seed coat PHD represents a problem for producers and consumers of several different market classes of dry bean. There are three post harvest darkening phenotypes: (i) non-darkening (ND), (ii) slow darkening (SD) and (iii) regular darkening (RD). The inheritance of PHD was determined by evaluating 28 populations derived from crosses between RD, SD and ND genotypes. Results suggest that at least two major, unlinked genes control the PHD trait in dry bean. Recessive epistasis with three phenotypic classes best explains the segregation ratios observed in populations from crosses between SD and ND parents. One gene, J, is responsible for whether a bean will darken and seeds of plants that are jj do not darken at all. Another gene, SD, influences the rate a seed coat will darken with seed from sdsd individuals darkening more slowly that those with the dominant SD allele. Quantitative evaluation of seed coat PHD demonstrated that there was a wide range of darkening within any given PHD phenotype. Crosses made between the ND x ND cross class resulted in F2 progeny that were all ND, however, a wide range of seed coat background colours was noted in the progeny. In several of the crosses made between ND x RD and SD x RD classes the resulting F1 progeny were all RD; however, a wide range of RD phenotypes were observed in the F2 progeny. These phenotypes are not likely due to quantitative trait loci (QTL) associated with the PHD trait, but rather a result of other chemical reactions occurring in the seed coat. Condensed tannins (CT; syn. proanthocyanidins), kaempferols, polyphenol oxidase (PPO) and possibly other compounds or enzymes may be interacting and causing this quantitative range within any given genotype as a function of environmental variability, genotype and their interaction. CT have been associated with PHD but are not responsible for the major difference between RD and SD lines. They may, however be responsible for the quantitative nature of the phenotype.<p> Condensed tannins can be harmful or beneficial to human health and the environment depending on the amount present and where it is found in the plant. Manipulating the production, accumulation and form of CT in the seed coat of dry bean would be beneficial to bean producers, consumers and breeders. This experiment quantitatively and qualitatively evaluated differences in patterns of CT accumulation in the seed coats of five genotypes of dry bean which exhibited low, medium or high concentrations of CT in their seed coats at maturity. Condensed tannin content was assessed from seeds harvested every other day from 6 40 days after flowering (DAF) using a modified BuOH-HCl assay. Results illustrated that CT accumulated as early in low CT genotypes as in high CT genotypes. CT content stabilized after 14 DAF in low CT genotypes. By contrast, CT content peaked then leveled off 30 DAF in moderate and high CT genotypes. A reduction in CT content in the higher CT lines was observed in the final stages of seed development.

Metal mines release treated effluents that contain a variety of metals, metalloids, and organics into the aquatic environment. A number of metal mine effluents (MMEs) have been found to contribute to adverse effects in fish and benthic invertebrates, such as decreased diversity and density, however the specific causal factors of toxic responses during chronic exposures to the MMEs are often unknown. Therefore, the overall objective of this dissertation was to explore causative and modifying factors of MME toxicity to a resident fish species, the fathead minnow (Pimephales promelas), during chronic, multi-trophic exposures. The representative MME used in this study was the process water effluent (PWE) of a Canadian metal mine, which is released into Junction Creek in Sudbury, Ontario, Canada. Chronic exposure to the MME has been a source of decreased reproductive output in fathead minnows in several previous studies, however, these same studies were not able to determine the potential causal factors of the reproductive impairment. In order to address the overall objective, several laboratory mesocosm studies were conducted, which consisted of three separate components. The first component included exploring several metals (Cu, Ni, and Se; alone and in mixture) that are consistently present in the MME and are known to cause toxicity at fairly low concentrations as potential causes for decreased egg production in fathead minnows. The second component included evaluating the role of decreased food availability (a possible indirect effect of MME in the receiving environment) as a potential cause of decreased egg production in fathead minnows. The third and final component included examining the role of water chemistry [(increased alkalinity and dissolved organic carbon (DOC)] as potential modifying factors of chronic MME toxicity to fathead minnows. In general, my results suggest that the metals present in the MME likely do not contribute directly to decreased reproductive performance in fathead minnows during chronic exposures, under the conditions examined. Instead, the MME appears to decrease food availability, therefore indirectly influence fathead minnow egg production. Furthermore, water chemistry modifications tested in this thesis were not able to entirely mitigate the reproductive effects in fish induced by the MME, although they did improve egg production relative to unmodified MME. Metal concentrations in fish tissues were not influenced by increases to alkalinity or DOC level in the exposure water, suggesting that bioavailability of metals during chronic exposure to metal-mixtures cannot be fully explained based on our understanding of metal complexation with abiotic ligands (inorganic and organic) during single metal or acute exposures. From a regulatory perspective, water chemistry modifications may somewhat improve fathead minnow reproductive performance during chronic exposure to the MME, however the MME would still not be entirely free of effects relative to the uncontaminated water. Future studies should focus on understanding the factors responsible for decreased food availability in MME-impacted aquatic ecosystems, and further explore potential approaches for ameliorating effluent quality.

Contaminated areas resulting from anthropogenic activities have, for the most part, concentrations of contaminants that exceed Tier 1 standards below which the risk is considered acceptable. However, contaminants that have been in soil for a prolonged period can become recalcitrant over time, due to various physico-chemical and biological processes. Sequestered and recalcitrant contaminants are not readily biologically available to living organisms. However, they are easily measured analytically because of the strong acid extractions that are used in the analytical methodologies. Because toxicity is a function of exposure concentration(s), exposure duration, and bioavailability, contaminants in soil can be present at concentrations that exceed established standards but they represent minimal risk to ecological receptors because the contaminants are not fully available. To predict toxicity and estimate risk, it is imperative that an accurate and reliable measure of bioavailability be available. Several surrogate measures of bioavailability were compared to the results of a battery of toxicity tests using Cu, Pb, and Zn-contaminated soils collected from a former industrial area and Cu and Zn-contaminated soils collected from a former mining site. CaCl₂extractions, hydroxypropyl-β-cyclodextrin (cyclodextrin) extractions, Simulated Earthworm Gut (SEG) tests, and bioaccumulation tests were performed using the soils. Overall, SEG-extractable Cu was most predictive of adverse effects in industrial soils, likely due to enzymatic activity and/or increased ionic strength of the solution. For the mining soils, all chemical measures of bioavailability correlated with several biological responses; however, CaCl₂-extractable Cu and SEG-extractable Cu and Zn best predicted earthworm responses. Total Cu concentrations in soil correlated best with adverse effects to plants. No method was a good predictor of all biological effects for a single organism when data from the two sites were combined. The SEG test may provide a good indication of metal toxicity at contaminated sites with varying soil physico-chemical characteristics but further validation is required.

Contaminated areas resulting from anthropogenic activities have, for the most part, concentrations of contaminants that exceed Tier 1 standards below which the risk is considered acceptable. However, contaminants that have been in soil for a prolonged period can become recalcitrant over time, due to various physico-chemical and biological processes. Sequestered and recalcitrant contaminants are not readily biologically available to living organisms. However, they are easily measured analytically because of the strong acid extractions that are used in the analytical methodologies. Because toxicity is a function of exposure concentration(s), exposure duration, and bioavailability, contaminants in soil can be present at concentrations that exceed established standards but they represent minimal risk to ecological receptors because the contaminants are not fully available. To predict toxicity and estimate risk, it is imperative that an accurate and reliable measure of bioavailability be available. Several surrogate measures of bioavailability were compared to the results of a battery of toxicity tests using Cu, Pb, and Zn-contaminated soils collected from a former industrial area and Cu and Zn-contaminated soils collected from a former mining site. CaCl₂extractions, hydroxypropyl-β-cyclodextrin (cyclodextrin) extractions, Simulated Earthworm Gut (SEG) tests, and bioaccumulation tests were performed using the soils. Overall, SEG-extractable Cu was most predictive of adverse effects in industrial soils, likely due to enzymatic activity and/or increased ionic strength of the solution. For the mining soils, all chemical measures of bioavailability correlated with several biological responses; however, CaCl₂-extractable Cu and SEG-extractable Cu and Zn best predicted earthworm responses. Total Cu concentrations in soil correlated best with adverse effects to plants. No method was a good predictor of all biological effects for a single organism when data from the two sites were combined. The SEG test may provide a good indication of metal toxicity at contaminated sites with varying soil physico-chemical characteristics but further validation is required.

Seed coat biochemistry and colour are highly variable in common bean (Phaseolus vulgaris) (syn. dry bean). Genetic studies of dry bean seed coat chemistry and colour have important implications in breeding efforts for improving nutrition and seed quality for consumer acceptance. The results of this thesis detail the phenotypic and genotypic characterization of seed coat post harvest darkening (PHD) in parents and progeny of crosses among them as well as the phenotypic characterization of seed coat condensed tannin (CT) accumulation in five genotypes of bean.<p> Seed coat PHD represents a problem for producers and consumers of several different market classes of dry bean. There are three post harvest darkening phenotypes: (i) non-darkening (ND), (ii) slow darkening (SD) and (iii) regular darkening (RD). The inheritance of PHD was determined by evaluating 28 populations derived from crosses between RD, SD and ND genotypes. Results suggest that at least two major, unlinked genes control the PHD trait in dry bean. Recessive epistasis with three phenotypic classes best explains the segregation ratios observed in populations from crosses between SD and ND parents. One gene, J, is responsible for whether a bean will darken and seeds of plants that are jj do not darken at all. Another gene, SD, influences the rate a seed coat will darken with seed from sdsd individuals darkening more slowly that those with the dominant SD allele. Quantitative evaluation of seed coat PHD demonstrated that there was a wide range of darkening within any given PHD phenotype. Crosses made between the ND x ND cross class resulted in F2 progeny that were all ND, however, a wide range of seed coat background colours was noted in the progeny. In several of the crosses made between ND x RD and SD x RD classes the resulting F1 progeny were all RD; however, a wide range of RD phenotypes were observed in the F2 progeny. These phenotypes are not likely due to quantitative trait loci (QTL) associated with the PHD trait, but rather a result of other chemical reactions occurring in the seed coat. Condensed tannins (CT; syn. proanthocyanidins), kaempferols, polyphenol oxidase (PPO) and possibly other compounds or enzymes may be interacting and causing this quantitative range within any given genotype as a function of environmental variability, genotype and their interaction. CT have been associated with PHD but are not responsible for the major difference between RD and SD lines. They may, however be responsible for the quantitative nature of the phenotype.<p> Condensed tannins can be harmful or beneficial to human health and the environment depending on the amount present and where it is found in the plant. Manipulating the production, accumulation and form of CT in the seed coat of dry bean would be beneficial to bean producers, consumers and breeders. This experiment quantitatively and qualitatively evaluated differences in patterns of CT accumulation in the seed coats of five genotypes of dry bean which exhibited low, medium or high concentrations of CT in their seed coats at maturity. Condensed tannin content was assessed from seeds harvested every other day from 6 40 days after flowering (DAF) using a modified BuOH-HCl assay. Results illustrated that CT accumulated as early in low CT genotypes as in high CT genotypes. CT content stabilized after 14 DAF in low CT genotypes. By contrast, CT content peaked then leveled off 30 DAF in moderate and high CT genotypes. A reduction in CT content in the higher CT lines was observed in the final stages of seed development.