Browsing by Subject "Cell membranes"
Now showing 1 - 6 of 6
Results Per Page
Sort Options
Item Anions in hydrophobic environments: liquid-liquid extraction of sulfate and chloride, and membrane transport of chloride(2005) Eller, Leah Renee; Sessler, Jonathan L.The transport of an anion across a lipid bilayer or the extraction of an anion into organic solution requires the stabilization of a charged species in a hydrophobic environment. Due to the similar energetic barriers of both processes, liquid-liquid extraction can potentially be used as a model for membrane transport. Carrier species that can efficiently extract anions from aqueous solutions into solvents such as chloroform, can potentially be utilized to facilitate the diffusion of those anions across a lipid bilayer or cell membrane. The research presented here explores the relationship between liquid-liquid extraction and membrane transport behavior. Chapter 1 presents an introduction to the equilibria reactions that are involved in extraction, the structure of lipid bilayers and a description of liposome models of cell membranes. Chapter 2 details the partitioning analysis of sulfate using radiotracers. Chapter 3 explores the chloride extraction behavior of several pyrrole-based molecules using radiotracer analysis. Chapter 4 details the extensive studies of chloride transport across lipid bilayers using liposome model membranes.Item Biochemical characterization of cell surface components of Candida albicans(Texas Tech University, 1982-12) Mendel, Susan Mari NegaardExtracellular material (ECM) was isolated from media in which yeast phase Candida albicans of unknown serotype was grown. Cold 95% ethanol precipitated the ECM and upon Sephadex G-50 chromatography, high and low molecular weight components were identified. They consisted of ECM 1 (30,000 Mr), ECM 2A (4,500-6,000 Mr), and ECM 2B (3,800 Mr). The ECM 2B was separated into two components upon ion exchange chromatography. Glucose and mannose are its carbohydrate moieties and proline, lysine and glutamic acid are its major amino acids. It appears to have more protein content than ECM 2B2 as evidenced by absorbance at 2 80 nm. ECM 2B2 contains only mannose and some protein composed mostly of proline, threonine and alanine. The components are neither strain-specific, nor produced only during yeast phase growth. The ECM were compared to material released from the cell surface upon treatment of whole cells with the nonspecific protease papain, and the disulfide bond reducer, dithiothreitol. An ECM 2A is produced upon both treatments. ECM 2B1 closely resembles a low molecular weight component produced upon DTT treatment, and ECM 2B2 is similar to the papain released molecule. The ECM appears to be present either on or within the cell surface of Candida albicans. The ECM did not appear to be strongly antigenic, although unpurified media did induce an antibody response.Item Estradiol stimulation of glucose transport in rat uterus(Texas Tech University, 1985-08) Meier, Daniel AlanA study of the mechanism of the estradiol-mediated increase in glucose transport in the uteri of ovariectomized rats was undertaken. An essential first step in this study was the characterization of the glucose transport process using plasma membrane vesicles. Uterine plasma membrane preparations were obtained by centrifugation on discontinuous sucrose gradients. The specific activity of the plasma membrane marker 5'-nucleotidase was increased 10-fold while the specific activity of an endoplasmic reticulum marker glucose-6-phosphatase was increased 3-fold. D-Glucose transport into plasma membrane vesicles was inhibited by sulfhydryl reagents, phloretin, and cytochalasin B. Uptake was prevented by high osmotic pressures. The Km of glucose transport was 12.2 +_ 1.1 mM. Transport was unaffected by sodium and was energy independent. 2-Deoxyglucose transport was determined in uteri of rats grouped by stages of the reproductive cycle, i.e., diestrus 1, diestrus 2, proestrus and estrus. The rate of 2-deoxyglucose transport was highest in proestrus and lowest in diestrus 1. The increase in glucose transport in ovariectomized rats was half-maximal at approximately 5 ng estradiol/rat and reached the maximal 2 to 3-fold response after 2 hours whether measured in whole tissue or in uterine plasma membrane vesicles. Estrone and estriol treatment resulted in a similiar 2-fold increase in glucose transport while progesterone and dihydrotestosterone had no effect. Injection of protein synthesis inhibitors cycloheximide and emetine resulted in an increase in the basal glucose transport rate while having no effect on the estradiolstimulated increase in glucose transport. Treatment with the transcriptional inhibitor actinomycin D resulted in a slight increase in glucose transport with no effect on the estradiol-stimulated increase in glucose transport. Antiestrogen treatment (nafoxidine and tamoxifen) resulted in a 85-90 % decrease in the total estradiol binding sites in the cytosol but did not effect the estradiol stimulated increase in 2-deoxyglucose transport in uterine tissue. Insulin injection (0.2 mg/rat) resulted in a 40 % increase in 2-deoxyglucose transport in 24 h-starved rats in contrast to the 200 % increase seen with estradiol treatment. Insulin and estradiol treatment together were not additive in regard to the increase in 2-deoxyglucose transport in tissue. Estradiol treatment did not change binding of [1251 ] insulin to uterine plasma membranes. Estradiol treatment resulted in a 3-fold increase in the Vmax with no apparent change in the Km for 2-deoxyglucose transport. Also, estradiol treatment did not result in an increase in the amount of glucose transporters in uterine plasma membranes as measured by antibodies raised against the glucose transporter protein from human erythrocytes. In summary, estradiol stimulates the rate of glucose transport in rat uterus by increasing the rate by which the transporter protein moves glucose across the plasma membrane .Item Motion of nano-objects in Langmuir monolayers(2003-05) Forstner, Martin Bernhard; Swinney, H. L., 1939-; Käs, Josef A.Item Polymannan enhancement of macrophage function(Texas Tech University, 1999-12) Gnade, Bryan ThomasPrevious studies have shown that mannosylated bovine semm albumin (mBSA) enhances the respiratory burst (RB), phagocytosis, and killing of Candida albicans and Escherichia coli by resident murine peritoneal macrophages (M0). Upregulation of the above M0 functions was associated with binding of mBSA to the macrophage mannose receptor. The present study was done to detennine if certain polymannans, and other glyconutrients could stimulate M0 functions in a similar manner. Resident peritoneal murine M0 collected from C57BL/6 mice were exposed to the glyconutrients for 10 and 60 minutes. The RB was measured using chemiluminescence. Both phagocytosis and killing were measured after incubation with one of the following microorganisms: Candida albicans, Escherichia coli and S. aureus. The percent phagocytosis and killing were determined using fluorescence microscopy. Results indicated little or no effect of four of these compounds on phagocytosis and killing Compound 3, which was identified as Ambrotose, caused a dose and time dependent effect on M0 induced killing of all 3 microorganisms.Item Speed and propagation of diffusive signals in spatially inhomogeneous membranes(2003) Martin, Douglas Stuart; Swinney, H. L., 1939-; Käs, Josef A.