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Regulation of the nitric oxide receptor, soluble guanylyl cyclase / Regulation des Rezeptor des Stickstoffoxides löslicher GuanylylcyclaseNedvetsky, Pavel I. January 2003 (has links) (PDF)
Soluble guanylyl cyclase (sGC) is the best established receptor for nitric oxide (NO) and regulates a great number of important physiological functions. Surprisingly, despite the wellappreciated roles of this enzyme in regulation of vascular tone, smooth muscle cell proliferation, platelet aggregation, renal sodium secretion, synaptic plasticity, and other functions, extremely little is known about the regulation of sGC activity and protein levels. To date, the only well-proven physiologically relevant sGC regulator is NO. In the present study, some additional possibilities for sGC regulation were shown. Firstly, we evaluated the ability of different NO donors to stimulate sGC. Significant differences in the sGC stimulation by SNP and DEA/NO were found. DEA/NO stimulated sGC much stronger than did SNP. Interestingly, no correlation between the sGC protein and maximal activity distribution was found in rat brain regions tested, suggesting the existence of some additional regulatory mechanisms for sGC. The failure of SNP to stimulate sGC maximally might be one of the reasons why the lack of correlation between the distribution of sGC activity and proteins in brain was not detected earlier. Prolonged exposure of endothelial cells to NO donors produced desensitization of the cGMP response. This desensitization cannot be explained by increased PDE activity, since PDE inhibitors were not able to prevent the NO donor-induced decrease of the maximal cGMP response in endothelial cells. The failure of SH-reducing agents to improve the cGMP response after its desensitization by NO suggests that a SH-independent mechanism mediates NO effects. Demonstration that the potency of the recently described activator of oxidized (heme-free) sGC, BAY58-2667, to stimulate sGC increases after prolonged exposure of the cells to an NO donor, DETA/NO, suggests that oxidation of heme may be a reason for NOinduced desensitization of sGC and decrease in sGC protein level. Indeed, the well-known heme-oxidizing agent ODQ produces a dramatic decrease in sGC protein levels in endothelial cells and BAY58-2667 prevents this effect. Although the mechanism of sGC activation and stabilization by BAY58-2667 is unknown, this substance is an interesting candidate to modulate sGC under conditions where sGC heme iron is oxidized. Very little is known about regulation of sGC by intracellular localization or translocation between different intracellular compartments. In the present study, an increase in sGC sensitivity to NO under membrane association was demonstrated. Treatment of isolated lung with VEGF markedly increased sGC in membrane fractions of endothelial cells. Failure of VEGF to stimulate sGC membrane association in cultured endothelial cells allows us to propose a complex mechanism of regulation of sGC membrane association and/or a transient character of sGC membrane attachment. A very likely mechanism for the attachment of sGC to membranes is via sGCinteracting proteins. These proteins may participate also in other aspects of sGC regulation. The role of the recently described sGC interaction partner, Hsp90, was investigated. Shortterm treatment of endothelial cells with an Hsp90 inhibitor does not affect NO donor or calcium ionophore-stimulated cGMP accumulation in the cells. However, inhibition of Hsp90 results in a rapid and dramatic decrease in sGC protein levels in endothelial cells. These effects were unrelated to changes in sGC transcription, since inhibition of transcription had much slower effect on sGC protein levels. In contrast, inhibitors of proteasomes abolished the reduction in sGC protein levels produced by an Hsp90 inhibitor, suggesting involvement of proteolytic degradation of sGC proteins during inhibition of Hsp90. All these data together suggest that Hsp90 is required to maintain mature sGC proteins. In conclusion, in the present study it was demonstrated that multiple mechanisms are involved in the regulation of sGC activity and its sensitivity to NO. Oxidation of sGC heme by NO seems to be one of the mechanisms for negative regulation of sGC in the presence of high or prolonged stimulation with NO. Another possible means of regulating sGC sensitivity to NO is via the intracellular translocation of the enzyme. It has been also demonstrated here that attachment of sGC to the membrane fraction results in an apparent increase in the enzyme sensitivity to NO. Additionally, Hsp90 was required to maintain sGC protein in endothelial and other cell types. However, we could not find any acute affect of Hsp90 on sGC activity, as reported recently. All these findings demonstrate that the regulation of sGC activity and protein level is a much more complex process than had been assumed earlier. / Lösliche Guanylylcyclase (sGC) ist der Hauptrezeptor für Stickstoffmonooxid (NO), der sich an der Regulation zahlreicher physiologischer Funktionen beteiligt. Trotz ihrer sehr gut untersuchten Rolle in der Regulation der Blutgefässenrelaxation, synaptische Plastizität, Aggregation der Trombozyten, renale Sekretion und anderen wichtigen Funktionen, ist die Regulation der sGC selber noch nicht ausreichend verstanden. Der einzige, zur Zeit bekannte, physiologische Regulator der sGC ist NO. In der vorgelegten Arbeit wurde die Existenz anderer Möglichkeiten der sGC Regulation gezeigt. Zuerst, wurde die Fähigkeit verschiedener NO Donoren sGC zu stimulieren untersucht. DEA/NO stimulierte sGC viel stärker als SNP. Interessanterweise, wurde keine Korrelation zwischen der Verteilung des sGC Proteins und der Enzymaktivität unter Vmax- Bedingungen in verschiedenen Rattenhirnregionen gefunden. Das deutet auf zusätzliche Regulationsmechanismen hin. Die fehlende Fähigkeit von SNP sGC maximal zu stimulieren könnte ein Grund dafür sein, warum dieses Phänomen nicht schon früher gezeigt wurde. Langfristige Behandlung von Endothelzellen mit NO Donoren produzierte eine Desensitisierung der nachfolgenden cGMP Antwort. Diese Desensitisierung kann nicht durch erhöhte Phosphodiesterase-Aktivität erklärt werden, da Phosphodiesterasenhemmer die durch NO Donor verursachte Abnahme der cGMP Antwort nicht rückgängig macht. SHreduzierende Substanzen waren nicht in der Lage die cGMP Antwort zu verbessern, was zur Annahme führt, dass SH-Gruppenoxidation keine wichtige Rolle bei der Wirkung von NO auf sGC spielt. Es müssen daher andere Regulationsmechanismen vorhanden sein. Oxidation des Häms scheint ein möglicher Mechanismus der NO-induzierten sGC Desensitisierung. Einkürzlich beschriebener Aktivator der oxidierten (bzw. Häm-freien) sGC, BAY58-2667, stimulierte sGC nach Vorbehandlung mit NO Donoreb stärker als ohne Vorbehandlung. Es wird vermutet, dass oxidierte sGC verstärkt abgebaut wird was die durch NO oder Häm oxidierende Substanzen induzierte sGC Proteinabnahme erklären würde. Tatsächlich, nahm sGC Proteinlevel nach der Behandlung mit der Häm oxidierenden Substanz, ODQ, ab. BAY58-2667 verhinderte diesen Effekt. Ferner erhöht die Membranassoziation von sGC derer Empfindlichkeit gegenüber NO. Die Membranassoziation der sGC in Endothelzellen ist reguliert. Behandlung isolierter Lunge mit VEGF erhöht den Anteil an membrangebundener sGC in Endothelzellen dramatisch. In kultivierten Endothelzellen könnte VEGF die Membranassoziation jedoch nicht stimulieren, was einen komplexen Mechanismus der Membranassoziation der sGC in vivo vermuten lässt. Wenig ist bekannt über die Interaktionen von sGC mit anderen Protein und der möglichen Rolle dieser Interaktionen bei der Regulation des Enzyms. Proteininteraktionen scheinen aber ein möglicher Mechanismus für die Membranassoziation der sGC zu sein. Aus diesem Grund wurde die Rolle eines vor kurzem beschriebenen sGC-bindenden Proteins, Hsp90, auf die sGC Regulation untersucht. Kurzfristige Behandlung der Endothelzellen mit Hsp90 Inhibitoren hat keine Auswirkung auf NO Donor- und Calciumionophore-stimulierte cGMP-Produktion. Langfristige Hemmung von Hsp90 führte dagegen zur schnellen und deutlichen Abnahme des sGC Proteins. Dieser Effekt ist nicht durch eine Veränderung der Translation zu erklären, weil Tranlationshemmer einen viel langsameren sGC Abfall verursachten. Im Gegenteil, konnte ein Proteasomeninhibitor, MG132, die Effekte von Hsp90 Hemmern rückgängig machen. Das lässt eine proteolytische Abbau der sGC für die Effekte von Hsp90 Hemmer verantwortlich machen. Diese Daten deuten darauf hin, dass Hsp90 für Aufrechterhaltung des Enzyms notwendig ist. Zusammenfassend, wurde in der vorliegenden Arbeit gezeigt, dass sGC Aktivität und ihre Empfindlichkeit gegenüber ihren Aktivator NO durch multiple Faktoren beeinflusst werden kann. Oxidation des Häms durch NO könnte ein Mechanismus der negativen Regulation der sGC bei dauernd erhöhter Konzentration von NO sein. Ein zusätzlicher Mechanismus der Regulation der Empfindlichkeit der sGC gegenüber NO scheint die intrazellulare Translokation zu sein. Wir konnten hier zeigen, das die Membranassoziation der sGC ihre Empfindlichkeit gegenüber NO erhöht. Auch dieProteinlevel der sGC scheinen unter Kontrolle verschiedener Faktoren zu sein. Einer davon ist Hsp90, der für die Aufrechterhaltung des sGC Proteins sowohl in Endothelzellen als auch in anderen Zelltypen notwendig ist. Alle diese Daten zeigen, dass Regulation der sGC ein viel komplexerer Vorgang ist als bis her angenommen wurde und eröffnen interessante neue Forschungsrichtungen innerhalb dieses wichtigen Signalweges.
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Government Regulation in the Wireless Telecommunications Industry: The Impact of Wireless Number PortabilityPemberton, Anne January 2013 (has links)
Thesis advisor: Frank Gollop / By November 2003, wireless telecommunications operators were required by the FCC to have implemented wireless number portability. The FCC and the media claimed that this decrease in the cost of switching would force operators to react competitively by either decreasing prices or increasing the services offered at the same price to prevent customers from migrating to competitors. This paper empirically analyzes the effect that this regulation had on plan prices offered by the top four U.S. cellular operators over the period of Q2 2002 through Q2 2008, identifying whether they increased or decreased and by how much. This paper concludes that three out of the four nationwide carriers lowered prices in response to the implementation of wireless number portability. / Thesis (BA) — Boston College, 2013. / Submitted to: Boston College. College of Arts and Sciences. / Discipline: Economics Honors Program. / Discipline: College Honors Program. / Discipline: Economics.
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Artemisinin Biosynthesis: Developmental and Sugar Regulation of mRNA LevelsVail, Daniel Robert 28 April 2008 (has links)
Artemisinin, produced by the plant Artemisia annua, is a sesquiterpene anti-malarial therapeutic. Due to the medicinal relevance of this plant product, there is significant interest in understanding how the biosynthetic pathway is regulated at several key steps. The objective of this study is to examine several factors known to influence artemisinin yields to determine if those effects are occurring at the transcriptional level of the biosynthetic pathway. Artemisinin content has been shown to increase as the plant shifts from vegetative growth to reproductive, flowering growth. To test whether there is a corresponding increase in terpenoid gene expression during the shift to reproductive growth, levels of mRNA of terpenoid genes were measured during flowering budding and full flowering and compared to those measured during vegetative growth. Results indicate that in response to the photoperiod signal to shift to reproductive growth, early cytosolic pathway genes were highly upregulated, while there was no change in early plastidic pathway genes. Late pathway genes specific to artemisinin synthesis were upregulated >6-fold. Furthermore, glucose has also been shown to stimulate artemisinin production compared to sucrose. To test whether glucose is acting as signal to increase terpenoid gene expression, levels of mRNA of terpenoid genes were measured in glucose- and fructose-treated seedlings and compared to those in sucrose-treated seedlings. Results indicate that in response to treatment with glucose, compared with sucrose, early pathway genes in both compartments were initially upregulated. Transcript levels subsequently decreased to levels similar to those in sucrose-treated seedlings. ADS was upregulated by glucose, compared with sucrose, reaching a peak at day 7. Finally, coordinate control of sterol and sesquiterpene synthesis at a critical branch-point in the terpenoid biosynthetic pathway has been demonstrated. To test whether amorpha-4,11-diene synthase (ADS) and squalene sythase (SQS) are coordinately regulated, levels of mRNA of those two genes were measured and compared in both experimental conditions. Results indicate that under the conditions used in this study, ADS and SQS did not show coordinate regulation. This study was the first to demonstrate that: 1. terpenoid genes relating to artemisinin biosynthesis are regulated at the level of transcript accumulation as the plant shifts from vegetative to reproductive growth; 2. glucose is acting as a signal in artemisinin biosynthesis by upregulating transcript levels for several terpenoid genes.
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Heat flow and metabolic reaction during dry ice coolingTechapatanarat, Paisan January 2011 (has links)
Digitized by Kansas Correctional Industries
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The role of 4E-T protein in the regulation of gene expressionKamenska, Anastasiia January 2015 (has links)
No description available.
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Towards the identification and characterisation of novel human cell cycle regulatorsWieser, Samuel Christoph January 2015 (has links)
No description available.
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Recently acceded members of the World Trade Organization : membership, the Doha Development Agenda, and dispute settlementTakamiya, Kenji January 2015 (has links)
No description available.
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Regulating for change? : influencing business contributions to peacebuildingMolloy, Sean Patrick January 2018 (has links)
Those actors that attempt to influence business approaches to social responsibility are typically concerned with preventing businesses from causing harm or holding businesses accountable for harmful activities when they occur. In post-conflict settings, these twin aims are particularly important given the innumerable instances of businesses undermining transitions from conflict to peace through harmful practices. However, businesses can also be positive agents of change. As an emerging discourse on business and peacebuilding is suggesting, businesses can contribute positively to transitions from conflict to peace in a range of ways. But can other actors influence businesses to engage in peacebuilding processes? Can they require, induce and persuade positive business-based contributions to peacebuilding? If so, how? Examining two case studies on Northern Ireland and South Africa, I will argue that different actors can influence businesses to act as peacebuilding agents. I use the findings from these case studies to consider opportunities for thinking about a global policy instrument on business and peacebuilding.
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Self-regulation of wealthSchink, Gregory H.G. 12 September 2018 (has links)
Doctor of Philosophy / Department of Human Ecology-Personal Financial Planning / Sonya Britt / The purpose of this study was to determine the influence of self-regulation on positive financial behaviors and bankruptcy filings of high net worth individuals. The implications are directed toward various groups and factions of high net worth individuals as populations of interest. The basic premise of self-regulation of behavior theory is that human action is driven by attainment of goals and the degrees and forms of behavior expressed by an individual can be quantified by specific personality characteristics which affect both the response to, and velocity toward, those goals (Carver & Scheier, 1998). A survey administered to high net worth individuals (i.e., net worth of $1 million or greater) with a oversampling of high net worth individuals who have filed bankruptcy focused on self-reporting personality measures key to the self-regulation of behavior theory, such as optimism-pessimism and appetitive motives. By utilizing data gathered from high net worth individuals, a t test was used to examine mean differences in the personality characteristics of high net worth individuals who have filed bankruptcy and high net worth individuals who have not filed bankruptcy. The debt-to-income and debt-to-assets ratios were utilized as the dependent variables in an OLS regression analysis to analyze if any of the variables of interest significantly influenced the debt-to-income ratio, or DTI, or debt-to-assets ratio, or debt-ratio. This was followed by a logistic regression analysis predicting the odds of a bankruptcy filing based on the variables of interest. Potential differences in personality and behavior may explain wealth management issues that exist between high net worth individuals who have filed bankruptcy and high net worth individuals who have not filed bankruptcy.
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Exploring Co-Regulatory Scaffolding Between a Coach and Figure Skater in Practice: A Case StudyBain, Lisa 13 November 2019 (has links)
Self-regulated learning (SRL) processes are frequently used by elite athletes and are thought to
be an important factor in the development of expertise (McCardle, Young, & Baker, 2017). Before learners become self-regulated, they must first be co-regulated by a more experienced other (Glaser, 1996), such as an instructor. Scaffolding, a form of co-regulation, has three conceptual characteristics: contingency, fading, and transfer of responsibility (van de Pol & Elbers, 2013). Of the little research done on scaffolding, most studies have been in the education domain with few looking at it in a naturalistic setting. This thesis represented a seminal investigation on the nature of scaffolding in a coach-athlete dyad. It aimed to explore scaffolding using a naturalistic, instrumental case study with an experienced female coach (aged 53, national level) and her competitive male figure skater (aged 15, provincial level) using a concurrent mixed methods design (Creswell, 2003). Data were collected through a) an athlete self-report survey on SRL at the beginning and end of data collection; b) participant observation, field notes, and audio recordings of coach-skater dialogue at 16 practices spread across 5 months of the season; and c) three separate interviews at mid-, late-, and post-season with the coach and skater. Study 1 presents results informed by the skater’s survey and quantitative analyses of audio transcripts. The skater’s self-report of the SRL-SP (Bartulovic, Young, & Baker, 2017) was higher at time two (post-season) compared to time one (mid-season), indicating an increase in SRL. Due to very poor reliability uncovered in pilot work, planned analyses to determine changes in the directionality of coach- and skater-initiated discussion and contingency at various points across the season could not be performed. Study 2 presents the results of thematic analysis (Braun & Clarke, 2006) on the interview data and audio transcript excerpts. Deductive analyses showed it was difficult to identify and describe aspects of the three scaffolding characteristics separately due to their overlapping conceptual definitions, and their interplay during practice. Inductive analyses revealed nuances of scaffolding in sport, including micro- and macro-level co-regulation. Micro-level co-regulation emerged as an important “interface” illustrated by mature coach-skater interactions surrounding practice trials. The interface involved shared and individual expectations for the coach and skater, roles, and described transitory processes relating the co-regulatory interface to the skater’s SRL. Fading in sport differed from the linear model in education with a cyclical pattern of engagement by the coach, returning to refine the skater’s elements if they were incorrect. After integrating and interpreting all the data, the findings suggested scaffolding manifests in unique ways in a sport dyad, with SRL representing a process goal of the interface.
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