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Intrinsic Mechanisms (intrinsic + mechanism)

Distribution by Scientific Domains

Life Sciences	60%
Physics and Astronomy	40%

Selected Abstracts

Microglia express functional 11,-hydroxysteroid dehydrogenase type 1,

GLIA, Issue 10 2010
Andres Gottfried-Blackmore
Abstract Glucocorticoids are potent regulators of inflammation exerting permissive, stimulatory, and suppressive effects. Glucocorticoid access to intracellular receptors is regulated by the activity of two distinct enzymes known as 11,-hydroxysteroid dehydrogenase (11,HSD) Type 1 and Type 2, which catalyze the activation or deactivation of glucocorticoids. Although expression of these enzymes in major organ systems and their roles in the metabolic effects of glucocorticoids have been described, their role in the inflammatory response has only recently started to be addressed. In this report, we have studied the expression and activity of 11,HSD Type 1 and Type 2 in microglia cells. Microglia, the brain's resident macrophages, initiate and orchestrate CNS inflammatory responses. Importantly, activated microglia are implicated in most neurodegenerative conditions, making them key subjects of study. We found that microglia expressed 11,HSD-1, but not 11,HSD-2, both in ex vivo FACS-sorted adult cells and in vitro primary cultures. 11,HSD-1 expression was increased in LPS-activated microglia. Moreover, 11,HSD-1 catalyzed the metabolic conversion of 11-dehydro-corticosterone into corticosterone (CORT), which potently reduced cytokine production in activated microglia. We propose that 11,HSD-1 may provide microglia with an intrinsic mechanism to autoregulate and inhibit proinflammatory mediator production through CORT formation. © 2010 Wiley-Liss, Inc. [source]

Secreted factors from ventral telencephalon induce the differentiation of GABAergic neurons in cortical cultures

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2006
H.-h. Trinh
Abstract It is widely believed that the pyramidal cells and interneurons of the cerebral cortex are distinct in their origin, lineage and genetic make up. In view of these findings, the current thesis is that the phenotype determination of cortical neurons is primarily directed by genetic mechanisms. Using in vitro assays, the present study demonstrates that secreted factors from ganglionic eminence (GE) of the ventral telencephalon have the potency to induce the differentiation of a subset of cortical neurons towards ,-aminobutyric acid (GABA)ergic lineage. Characterization of cortical cultures that were exposed to medium derived from GE illustrated a significant increase in the number of GABA-, calretinin- and calbindin-positive neurons. Calcium imaging together with pharmacological studies showed that the application of exogenous medium significantly elevated the intracellular calcium transients in cortical neurons through the activation of ionotropic glutamate receptors. The increase in GABA+ neurons appeared to be associated with the elevated calcium activity; treatment with blockers specific for glutamate receptors abolished both the synchronized transients and reduced the differentiation of GABAergic neurons. Such studies demonstrate that although intrinsic mechanisms determine the fate of cortical interneurons, extrinsic factors have the potency to influence their neurochemical differentiation and contribute towards their molecular diversity. [source]

Band alignment at metal,semiconductor and metal,oxide interfaces

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 2 2010
John Robertson
Abstract The mechanisms of Schottky barrier formation are reviewed from the metal-induced gap state model to the universal defect model, and the chemical reaction model. The recent progress in understanding barrier heights and band offsets in Si , high dielectric constant oxide and metal high dielectric constant oxide systems is then discussed, and interesting they contain components of each model. The greater emphasis on understanding defect reactions has allowed us to separate the effects of intrinsic mechanisms, metal induced gap states (MIGS) and extrinsic mechanisms (defects). [source]

Intrinsic decoherence in the interaction of two fields with a two-level atom

ANNALEN DER PHYSIK, Issue 6 2009
R. Juárez-Amaro
Abstract We study the interaction of a two-level atom and two fields, one of them classical. We obtain an effective Hamiltonian for this system by using a method recently introduced that produces a small rotation to the Hamiltonian that allows to neglect some terms in the rotated Hamiltonian. Then we solve a variation of the Schrödinger equation that models decoherence as the system evolves through intrinsic mechanisms beyond conventional quantum mechanics rather than dissipative interaction with an environment. [source]

Neural stem cells: Mechanisms of fate specification and nuclear reprogramming in regenerative medicine

BIOTECHNOLOGY JOURNAL, Issue 12 2008
Carsten W. Lederer
Abstract Recently, intense interest in the potential use of neural stem cells (NSC) in the clinical therapy of brain disease and injury has resulted in rapid progress in research on the properties of NSC, their innate and directed differentiation potential and the induced reprogramming of differentiated somatic cells to revert to a pluripotent NSC-like state. The aim of this review is to give an overview of our current operational definitions of the NSC lineage, the growing understanding of extrinsic and intrinsic mechanisms, including heritable but reversible epigenetic chromatin modifications that regulate the maintenance and differentiation of NSC in vivo, and to emphasize ground-breaking efforts of cellular reprogramming with the view to generating patient-specific stem cells for cell replacement therapy. This is set against a summary of current practical procedures for the isolation, research and application of NSC, and of the state of the art in NSC-based regenerative medicine of the nervous system. Both provide the backdrop for the translation of recent findings into innovative clinical applications, with the hope of increasing the safety, efficiency and ethical acceptability of NSC-based therapies in the near future. [source]