Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 126-141). Also available on the Internet.

Type 2 diabetes (T2DM) is a chronic disease characterized by cellular insulin resistance and consequent disturbances in glucose metabolism. Long-term consumption of buckwheat has been previously shown to improve glycemia in individuals with T2DM; however, the underlying mechanisms as well as the contribution of improved acute glycemic responses have not been fully characterized. The current study used cell culture and clinical studies to investigate the mechanisms and effectiveness of common buckwheat for acute modulation of glucose metabolism and glycemia. Glucose uptake was inhibited in H4IIE cells treated with a buckwheat extract (BWE), an effect attributed to the actions of an unknown compound(s). Reduced glucose uptake and transepithelial glucose transport was also present in Caco2 colorectal adenocarcinoma cells and monolayers. The mechanism behind inhibited glucose uptake did not involve modulation of several signaling pathways regulating glucose metabolism, including p38 MAPK, p42/44 ERK, PI3Kγ, PKC, PKA, mTOR and AMPK. Interestingly, BWE treatment was associated with other effects on glucose metabolism, including elevated glucose production and levels of gluconeogenic enzymes. However, these effects were not mediated through the classical pathway of CREB activation involving cyclic AMP and PKA. In a blinded, reference product-controlled study, consumption of a cracker product made from whole grain common buckwheat flour containing 50 grams of available carbohydrate was not associated with changes in post-prandial glucose or insulin concentrations in both healthy individuals and those with diet-controlled T2DM. However, consumption of buckwheat crackers was associated with changes in selected gastrointestinal satiety hormones. Interestingly, several significant correlations observed between fasting concentrations and the overall post-prandial response of these hormones were affected by T2DM. In conclusion, glucose-lowering effects of common buckwheat are not due to the actions of known bioactive compounds, and may involve direct inhibition of facilitative transporters by a novel compound. Although a buckwheat food product did not reduce post-prandial glycemia, identifying the compound responsible for inhibited glucose uptake will allow development of food products enriched with this compound, and may represent a more effective dietary approach to managing glycemia.

The thermodynamic properties of bioactive peptides determine how they interact with cellular assemblies. Ultrasonic velocity and density measurements were used to analyse the volumetric properties in aqueous solution of 3 different materials: KCl, bioactive peptides (from hemp seed and dairy proteins), and liposomes (cell membrane models), as well as the interaction between peptides and liposomes. Serial dilutions of the three different materials showed linear relationships between density and concentration and between ultrasonic velocity and concentration. The apparent specific volume and apparent specific compressibility in solution of all materials showed concentration dependence as a result of increased electrostriction as solutions were diluted. The experimental ultrasonic velocities of liposome-dairy peptide mixes were higher than the theoretical additive value, due to interactions between liposomes and peptides. My research demonstrates the benefits of precise volumetric assessments in biological assays.

Type 2 diabetes (T2DM) is a chronic disease characterized by cellular insulin resistance and consequent disturbances in glucose metabolism. Long-term consumption of buckwheat has been previously shown to improve glycemia in individuals with T2DM; however, the underlying mechanisms as well as the contribution of improved acute glycemic responses have not been fully characterized. The current study used cell culture and clinical studies to investigate the mechanisms and effectiveness of common buckwheat for acute modulation of glucose metabolism and glycemia. Glucose uptake was inhibited in H4IIE cells treated with a buckwheat extract (BWE), an effect attributed to the actions of an unknown compound(s). Reduced glucose uptake and transepithelial glucose transport was also present in Caco2 colorectal adenocarcinoma cells and monolayers. The mechanism behind inhibited glucose uptake did not involve modulation of several signaling pathways regulating glucose metabolism, including p38 MAPK, p42/44 ERK, PI3Kγ, PKC, PKA, mTOR and AMPK. Interestingly, BWE treatment was associated with other effects on glucose metabolism, including elevated glucose production and levels of gluconeogenic enzymes. However, these effects were not mediated through the classical pathway of CREB activation involving cyclic AMP and PKA. In a blinded, reference product-controlled study, consumption of a cracker product made from whole grain common buckwheat flour containing 50 grams of available carbohydrate was not associated with changes in post-prandial glucose or insulin concentrations in both healthy individuals and those with diet-controlled T2DM. However, consumption of buckwheat crackers was associated with changes in selected gastrointestinal satiety hormones. Interestingly, several significant correlations observed between fasting concentrations and the overall post-prandial response of these hormones were affected by T2DM. In conclusion, glucose-lowering effects of common buckwheat are not due to the actions of known bioactive compounds, and may involve direct inhibition of facilitative transporters by a novel compound. Although a buckwheat food product did not reduce post-prandial glycemia, identifying the compound responsible for inhibited glucose uptake will allow development of food products enriched with this compound, and may represent a more effective dietary approach to managing glycemia.

The thermodynamic properties of bioactive peptides determine how they interact with cellular assemblies. Ultrasonic velocity and density measurements were used to analyse the volumetric properties in aqueous solution of 3 different materials: KCl, bioactive peptides (from hemp seed and dairy proteins), and liposomes (cell membrane models), as well as the interaction between peptides and liposomes. Serial dilutions of the three different materials showed linear relationships between density and concentration and between ultrasonic velocity and concentration. The apparent specific volume and apparent specific compressibility in solution of all materials showed concentration dependence as a result of increased electrostriction as solutions were diluted. The experimental ultrasonic velocities of liposome-dairy peptide mixes were higher than the theoretical additive value, due to interactions between liposomes and peptides. My research demonstrates the benefits of precise volumetric assessments in biological assays.

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references. Also available on the World Wide Web.

Thesis (M. Sc.)--University of Canterbury, 2008. / Typescript (photocopy). "March 2008." Includes bibliographical references (leaves 88-94). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 201-220). Also available in print.

Thesis (Ph. D.)--Washington State University, May 2009. / Title from PDF title page (viewed on Apr. 19, 2010). "College of Pharmacy." Includes bibliographical references.

Thesis (Ph. D.)--Rutgers University, 2008. / "Graduate Program in Biomedical Engineering." Includes bibliographical references (p. 132-136).