1,176 research outputs found
Endosomal reflux of catalytically active cathepsins during chronic ex vivo muscarinic stimulation of lacrimal gland acinar cells
No full textGoing Deutsch (dissertation): Heritage Tourism and Identity in German Texas
No full text"Dissertation presented to the Faculty of the Graduate School of The University of Texas at Austin in Partial Fulfillment of the Requirements
for the Degree of Doctor of Philosophy.
Association between single nucleotide polymorphisms in the 3'untranslated region of the SRD5A2 gene and prostate cancer risk
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Complex subcellular distribution of sodium-dependent amino acid transport systems in kidney cortex and LLC-PK1/Cl4 cells
No full textComplex subcellular distribution of sodium-dependent amino acid transport systems in kidney cortex and LLC-PK1/Cl4 cells. To characterize the amino acid transport system in basalateral membranes and to test for possible intracellular loci of amino acid transport activity, we surveyed the distribution of L-alanine transport activity in rabbit proximal tubular cells and LLC-PK1/Cl4 cells. A three-dimensional separation procedure based on differential sedimentation, density gradient centrifugation, and counter-current distribution resolved 21 physically and biochemically distinct membrane populations from rabbit cortex. Inhibition of L-alanine transport by phenylalanine and N-(methylamino)isobutyric acid was used to delineate parallel amino acid transport pathways. Population n was identified as brush border membranes by virtue of its 16-fold maltase enrichment; 94% of its Na+-dependent alanine transport activity was mediated by systems previously shown to be characteristic of brush border membranes. Two populations, c′ and c″, which accounted for 25% of the total Na,K-ATPase activity, were identified as basalateral membranes on the basis of Na,K-ATPase cumulative enrichment factors of 15 and 21; 82% of the total alanine transport in these populations was mediated by a Na+-independent system similar to the classical system L. Na,K-ATPase, Na+-independent and Na+-dependent alanine transport activities were associated with intracellular membrane populations as well as with the plasma membranes. The major intracellular locus of Na,K-ATPase activity, population i accounted for roughly 31% of the Na,K-ATPase, maximally enriched ninefold; it contained 29% of the total system L transport activity. Population l, which was identified as endoplasmic reticulum because it was the major locus of membrane-bound NADPH cytochrome c reductase activity, contained 44% of the total system A transport. Three distinct Golgi-derived populations, m′, m″, and o, accounted for 39% of the total system A transport. A survey of the amino acid transport systems in LLC-PK1/Cl4 cells showed that the majority of system A-mediated amino acid transport was present in membranes of intracellular and possibly apical origin. The presence of large intracellular pools of amino acid transport activities might reflect newly synthesized transport proteins, ongoing membrane recycling or, perhaps, intracellular reserves available for rapid recruitment to the plasma membrane
[2] Isolation of plasma membranes from polar cells and tissues: Apical/basolateral separation, purity, function
No full textThe construction of Karen Karnak: The multi-author-function
No full textThis thesis is situated within the comparatively recent developments of Web 2.0 and the emergence of interactive WikiMedia, and explores the mode of authorship within a Read/Write culture compared to that of a Read/Only tradition. The hypothesis of this study is that the role of the audience has become merged with the author, and as such, represents new functions and attributes, distinct from a more conventional concept of authorship, in which the roles of audience and author are more separate. Read/Write and participatory culture, as defined by this study, is focused on collaboration, and includes the influences of D.I.Y. culture, Open-Source practices and the production of text by multiple authors. Multi-authorship presents a re-thinking of several concepts which support the notion of the individual author, since the focus of multi-authorship is not on attribution and ownership of a finished text, but on the continued malleability of a text. Modes of multi-authorship, demonstrated in the use of the pseudonyms Alan Smithee and Karen Eliot, represent declarative authors whose names signify multiple origins, whilst concurrently indicating a distinct body of work. The function of these names form an important context to this study, since primary research involves the construction of an experimental mode of multi-authorship utilising WikiMedia technology and the interaction of thirty nine participants, who are invited to create a body of work under the collective pseudonym Karen Karnak. The data generated by this experiment is analysed using aspects of Michel Foucault's author-function to identify and determine power structures inherent in the WikiMedia context. The interplay of power structures, including concepts such as identity, ownership and the body of work, affect the resulting mode of authorship and contribute to the construction of Karen Karnak, suggesting further areas of research into the emerging multi-author
Reversible effects of acute hypertension on proximal tubule sodium transporters
No full textAcute hypertension provokes a rapid decrease in proximal tubule sodium reabsorption with a decrease in basolateral membrane sodium-potassium-ATPase activity and an increase in the density of membranes containing apical membrane sodium/hydrogen exchangers (NHE3) [Y. Zhang, A. K. Mircheff, C. B. Hensley, C. E. Magyar, D. G. Warnock, R. Chambrey, K.-P. Yip, D. J. Marsh, N.-H. Holstein-Rathlou, and A. A. McDonough. Am. J. Physiol.270 ( Renal Fluid Electrolyte Physiol.39): F1004–F1014, 1996]. To determine the reversibility and specificity of these responses, rats were subjected to 1) elevation of blood pressure (BP) of 50 mmHg for 5 min, 2) restoration of normotension after the first protocol, or 3) sham operation. Systolic hypertension increased urine output and endogenous lithium clearance three- to fivefold within 5 min, but these returned to basal levels only 15 min after BP was restored. Renal cortex lysate was fractionated on sorbitol gradients. Basolateral membrane sodium-potassium-ATPase activity (but not subunit immunoreactivity) decreased one-third to one-half after BP was elevated and recovered after BP was normalized. After BP was elevated, 55% of the apical NHE3 immunoreactivity, smaller fractions of sodium-phosphate cotransporter immunoreactivity, and apical alkaline phosphatase and dipeptidyl-peptidase redistributed to membranes of higher density enriched in markers of the intermicrovillar cleft (megalin) and endosomes (Rab 4 and Rab 5), whereas density distributions of the apical cytoskeleton protein villin were unaltered. After 20 min of normalized BP, all the NHE3 and smaller fractions of the other apical membrane proteins returned to their original distributions. These findings suggest that the dynamic regulation of proximal tubule sodium transport by acute changes in BP may be mediated by rapid reversible regulation of sodium pump activity and relocation of apical sodium transporters.</jats:p
Characterization of microtubule motors in the apical trafficking of hydrogen,potassium-ATPase in oxyntic cells
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