3,217 research outputs found

    Natural and Synthetic Corticosteroids Inhibit Uptake\u3csub\u3e2\u3c/sub\u3e-Mediated Transport in CNS Neurons

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    In addition to exerting actions via mineralocorticoid and glucocorticoid receptors, corticosteroids also act by inhibiting uptake2, a high-capacity monoamine transport system originally described in peripheral tissues. Recent studies have demonstrated that uptake2 transporters are expressed in the brain and play roles in monoamine clearance, suggesting that they mediate some corticosteroid effects on physiological and behavioral processes. However, the sensitivity of brain uptake2 to many natural and synthetic corticosteroids has not been characterized. Cultured rat cerebellar granule neurons (CGNs) were previously shown to exhibit corticosterone-sensitive accumulation of the uptake2 substrate1-methyl-4-phenylpyridinium (MPP+). We examined the expression of uptake1 and uptake2 transporters in CGNs, and tested the effects of a variety of natural and synthetic corticosteroids on accumulation of [3H]-MPP+ by these cells. Cultured rat CGNs expressed mRNA for three uptake2-like transporters: organic cation transporters 1 and 3, and the plasma membrane monoamine transporter. They did not express mRNA for the dopamine or norepinephrine transporters, and expressed very little mRNA for the serotonin reuptake transporter. Accumulation of [3H]-MPP+ by CGNs was dose-dependently inhibited by corticosterone and decynium-22, known inhibitors of uptake2. Accumulation of MPP+ was also dose-dependently inhibited, with varying efficacies, by aldosterone, 11-deoxycorticosterone, cortisol, and cortisone, and by the synthetic glucocorticoids betamethasone, dexamethasone and prednisolone, and the glucocorticoid receptor antagonist RU38486. These studies demonstrate that uptake2 in the CNS is inhibited by a variety of natural and synthetic corticosteroids, and suggest that inhibition of uptake2-mediated monoamine clearance may underlie some behavioral and physiological effects of these hormones

    Bottom-up or Top-down? Removing the Privacy Law Obstacles to Healthcare Reform in the National Healthcare Crisis

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    Issues of healthcare availability and quality are among the most profound facing our nation. If a high-quality, accessible healthcare system of a truly national nature is to be devised, electronic connectivity—including increased use of electronic medical records and similar technological advances—must be a key feature. Yet such connectivity may give rise to patients’ concerns regarding the privacy of their medical information. Because such concerns demand respect, a challenge lies in balancing patients’ privacy interests against the important information-sharing interests underlying a national healthcare network. The Health Insurance Portability & Accountability Act (HIPPAA) is a key federal law that addresses many privacy issues regarding patients’ medical information, but HIPAA does not preempt state laws that furnish greater privacy protection than HIPAA provides. Accordingly, there exists a patchwork quilt of differing privacy protection provisions. This Article explores the issues just outlined and stresses the importance of a stronger federal role in standardizing medical information privacy rules, so that the current patchwork quilt of privacy regulations does not impede the development of a national healthcare network

    Bottom-up or Top-down? Removing the Privacy Law Obstacles to Healthcare Reform in the National Healthcare Crisis

    Get PDF
    Issues of healthcare availability and quality are among the most profound facing our nation. If a high-quality, accessible healthcare system of a truly national nature is to be devised, electronic connectivity—including increased use of electronic medical records and similar technological advances—must be a key feature. Yet such connectivity may give rise to patients’ concerns regarding the privacy of their medical information. Because such concerns demand respect, a challenge lies in balancing patients’ privacy interests against the important information-sharing interests underlying a national healthcare network. The Health Insurance Portability & Accountability Act (HIPPAA) is a key federal law that addresses many privacy issues regarding patients’ medical information, but HIPAA does not preempt state laws that furnish greater privacy protection than HIPAA provides. Accordingly, there exists a patchwork quilt of differing privacy protection provisions. This Article explores the issues just outlined and stresses the importance of a stronger federal role in standardizing medical information privacy rules, so that the current patchwork quilt of privacy regulations does not impede the development of a national healthcare network

    Corticosterone Acts in the Nucleus Accumbens to Enhance Dopamine Signaling and Potentiate Reinstatement of Cocaine Seeking

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    Stressful life events are important contributors to relapse in recovering cocaine addicts, but the mechanisms by which they influence motivational systems are poorly understood. Studies suggest that stress may “set the stage” for relapse by increasing the sensitivity of brain reward circuits to drug-associated stimuli. We examined the effects of stress and corticosterone on behavioral and neurochemical responses of rats to a cocaine prime after cocaine self-administration and extinction. Exposure of rats to acute electric footshock stress did not by itself reinstate drug-seeking behavior but potentiated reinstatement in response to a subthreshold dose of cocaine. This effect of stress was not observed in adrenalectomized animals, and was reproduced in nonstressed animals by administration of corticosterone at a dose that reproduced stress-induced plasma levels. Pretreatment with the glucocorticoid receptor antagonist RU38486 did not block the corticosterone effect. Corticosterone potentiated cocaine-induced increases in extracellular dopamine in the nucleus accumbens (NAc), and pharmacological blockade of NAc dopamine receptors blocked corticosterone-induced potentiation of reinstatement. Intra-accumbens administration of corticosterone reproduced the behavioral effects of stress and systemic corticosterone. Corticosterone treatment acutely decreased NAc dopamine clearance measured by fast-scan cyclic voltammetry, suggesting that inhibition of uptake2-mediated dopamine clearance may underlie corticosterone effects. Consistent with this hypothesis, intra-accumbens administration of the uptake2 inhibitor normetanephrine potentiated cocaine-induced reinstatement. Expression of organic cation transporter 3, a corticosterone-sensitive uptake2 transporter, was detected on NAc neurons. These findings reveal a novel mechanism by which stress hormones can rapidly regulate dopamine signaling and contribute to the impact of stress on drug intake

    A comparative study of WASP-67b and HAT-P-38b from WFC3 data

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    Atmospheric temperature and planetary gravity are thought to be the main parameters affecting cloud formation in giant exoplanet atmospheres. Recent attempts to understand cloud formation have explored wide regions of the equilibrium temperature-gravity parameter space. In this study, we instead compare the case of two giant planets with nearly identical equilibrium temperature (TeqT_\mathrm{eq} 1050K\sim 1050 \, \mathrm{K}) and gravity (g10ms1)g \sim 10 \, \mathrm{m \, s}^{-1}). During HSTHST Cycle 23, we collected WFC3/G141 observations of the two planets, WASP-67 b and HAT-P-38 b. HAT-P-38 b, with mass 0.42 MJ_\mathrm{J} and radius 1.4 RJR_\mathrm{J}, exhibits a relatively clear atmosphere with a clear detection of water. We refine the orbital period of this planet with new observations, obtaining P=4.6403294±0.0000055dP = 4.6403294 \pm 0.0000055 \, \mathrm{d}. WASP-67 b, with mass 0.27 MJ_\mathrm{J} and radius 0.83 RJR_\mathrm{J}, shows a more muted water absorption feature than that of HAT-P-38 b, indicating either a higher cloud deck in the atmosphere or a more metal-rich composition. The difference in the spectra supports the hypothesis that giant exoplanet atmospheres carry traces of their formation history. Future observations in the visible and mid-infrared are needed to probe the aerosol properties and constrain the evolutionary scenario of these planets.Comment: 16 pages, 17 figures, 8 tables, accepted for publication in The Astronomical Journa
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