Functional desensitization of the isolated beta-adrenergic receptor by the beta-adrenergic receptor kinase: potential role of an analog of the retinal protein arrestin (48-kDa protein).

The beta-adrenergic receptor kinase is an enzyme, possibly analogous to rhodopsin kinase, that multiply phosphorylates the beta-adrenergic receptor only when it is occupied by stimulatory agonists. Since this kinase may play an important role in mediating the process of homologous, or agonist-specific, desensitization, we investigated the functional consequences of receptor phosphorylation by the kinase and possible analogies with the mechanism of action of rhodopsin kinase. Pure hamster lung beta 2-adrenergic receptor, reconstituted in phospholipid vesicles, was assessed for its ability to mediate agonist-promoted stimulation of the GTPase activity of coreconstituted stimulatory guanine nucleotide-binding regulatory protein. When the receptor was phosphorylated by partially (approximately 350-fold) purified preparations of beta-adrenergic receptor kinase, as much as 80% inactivation of its functional activity was observed. However, the use of more highly purified enzyme preparations led to a dramatic decrease in the ability of phosphorylation to inactivate the receptor such that pure enzyme preparations (approximately 20,000-fold purified) caused only minimal (approximately 1off/- 7%) inactivation. Addition of pure retinal arrestin (48-kDa protein or S antigen), which is involved in enhancing the inactivating effect of rhodopsin phosphorylation by rhodopsin kinase, led to partial restoration of the functional effect of beta-adrenergic receptor kinase-promoted phosphorylation (41 +/- 3% inactivation). These results suggest the possibility that a protein analogous to retinal arrestin may exist in other tissues and function in concert with beta-adrenergic receptor kinase to regulate the activity of adenylate cyclase-coupled receptors.

Hannah Arendt's Theory of Political Judgment

Hannah Arendt's theory of political judgment has been an ongoing perplexity among scholars who have written on her. As a result, her theory of judgment is often treated as a suggestive but unfinished aspect of her thought. Drawing on a wider array of sources than is commonly utilized, I argue that her theory of political judgment was in fact the heart of her work. Arendt's project, in other words, centered around reestablishing the possibility of political judgment in a modern world that historically has progressively undermined it. In the dissertation, I systematically develop an account of Arendt's fundamentally political and non-sovereign notion of judgment. We discover that individual judgment is not arbitrary, and that even in the complex circumstances of the modern world there are valid structures of judgment which can be developed and dependably relied upon. The result of this work articulates a theory of practical reason which is highly compelling: it provides orientation for human agency which does not rob it of its free and spontaneous character; shows how we can improve and cultivate our political judgment; and points the way toward the profoundly intersubjective form of political philosophy Arendt ultimately hoped to develop.

Visual Disobedience: The Geopolitics of Experimental Art in Central America, 1990-Present

This dissertation centers on the relationship between art and politics in postwar Central America as materialized in the specific issues of racial and gendered violence that derive from the region's geopolitical location and history. It argues that the decade of the 1990s marks a moment of change in the region's cultural infrastructure, both institutionally and conceptually, in which artists seek a new visual language of experimental art practices to articulate and conceptualize a critical understanding of place, experience and knowledge. It posits that visual and conceptual manifestations of violence in Central American performance, conceptual art and installation extend beyond a critique of the state, and beyond the scope of political parties in perpetuating violent circumstances in these countries. It argues that instead artists use experimental practices in art to locate manifestations of racial violence in an historical system of domination and as a legacy of colonialism still witnessed, lived, and learned by multiple subjectivities in the region. In this postwar period artists move beyond the cold-war rhetoric of the previous decades and instead root the current social and political injustices in what Aníbal Quijano calls the `coloniality of power.' Through an engagement of decolonial methodologies, this dissertation challenges the label "political art" in Central America and offers what I call "visual disobedience" as a response to the coloniality of seeing. I posit that visual colonization is yet another aspect of the coloniality of power and indispensable to projects of decolonization. It offers an analysis of various works to show how visual disobedience responds specifically to racial and gender violence and the equally violent colonization of visuality in Mesoamerica. Such geopolitical critiques through art unmask themes specific to life and identity in contemporary Central America, from indigenous genocide, femicide, transnational gangs, to mass imprisonments and a new wave of social cleansing. I propose that Central American artists--beyond an anti-colonial stance--are engaging in visual disobedience so as to construct decolonial epistemologies in art, through art, and as art as decolonial gestures for healing.