196,279 research outputs found
Mechanisms of axonal degeneration in EAE - lessons from CNTF and MHC I knockout mice
No full textThe major pathological hallmarks of multiple sclerosis (MS) comprise inflammation, demyelination with associated gliosis and axonal damage, which most likely correlates with persisting disability. Axonal damage can occur by several mechanisms. This article focuses on myelin disintegration and direct immune attack on axons by CD8-positive T-cells as two possible scenarios for axonal injury. As protoypic models, we investigated experimental autoimmune encephalomyelitis (EAE) in ciliary neurotrophic factor gene knockout mice (CNTF-/- mice) with severe myelin pathology and EAE in beta-2 microglobulin gene knockout mice (beta 2m-/- mice) lacking CD8-positive T-cells. The results from these studies indicate that the trigger attack for axonal injury even in a well-defined experimental design can be multi-facetted. No single factor seems to be absolutely necessary for the initiation of the process, but they rather act in concert and orchestrate tissue destruction, inflammation and regeneration. Some mechanisms of primary or secondary axonal damage may be shared between inflammatory and degenerative diseases of the nervous system, thereby establishing a link which might be of importance for future therapeutic strategies. (c) 2005 Elsevier B.V. All rights reserved
Contribution of Ca2+-permeable AMPA/KA receptors to glutamate-induced Ca2+ rise in embryonic lumbar motoneurons in situ
No full textIntracellular Ca2+ ([Ca2+](i)) was fluorometrically measured with fura-2 in lumbar motoneurons of acutely isolated spinal cord slices from embryonic rats. In ester-loaded cells, bath-applied glutamate (3 mu M to 1 mM) evoked a [Ca2+](i) increase by up to 250 nM that was abolished by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) plus 2-amino-5-phosphonovalerate (APV). CNQX or APV alone reduced the response by 82 and 25%, respectively. The glutamatergic agonists kainate (KA), quisqualate (QUI), and S-alpha-amino-3-hydroxy-5-methyl-4-isoxalone (S-AMPA) evoked a similar [Ca2+](i) transient as glutamate. N-methyl-D-aspartate (NMDA) was only effective to increase [Ca2+](i) in Mg2+-free saline, whereas [1S,3R]-1-aminocyclopentane-1,3-dicarboxylic acid([1S,3R]ACPD) had no effect. The glutamate-induced [Ca2+](i) rise was suppressed in Ca2+-free superfusate. Depletion of Ca2+ stores with cyclopiazonic acid (CPA) did not affect the response. Thirty-six percent of the [Ca2+](i) increase in response to membrane depolarization induced by a 50 mM K+ solution persisted on combined application of the voltage-gated Ca2+ channel blockers nifedipine, omega-conotoxin-GVIA and omega-agatoxin-IVA. In fura-2 dialyzed motoneurons, the glutamate-induced [Ca2+](i) increase was attenuated by similar to 70% after changing from current to voltage clamp. Forty percent of the remaining [Ca2+], transient and 20% of the concomitant inward current of 0.3 nA were blocked by Joro spider toxin-3 (JSTX). The results show that voltage-gated Ca2+ channels, including a major portion of R-type channels, constitute the predominant component of glutamate-induced [Ca2+](i) rises. NMDA and Ca2+-permeable KA/AMPA receptors contribute about equally to the remaining component of the Ca2+ rise. The results substantiate previous assumptions that Ca2+ influx through JSTX-sensitive KA/AMPA receptors is involved in (trophic) signaling in developing motoneurons
Contribution of Ca2+-permeable AMPA/KA receptors to glutamate-induced Ca2+ rise in embryonic lumbar motoneurons in situ
No full textIntracellular Ca2+ ([Ca2+](i)) was fluorometrically measured with fura-2 in lumbar motoneurons of acutely isolated spinal cord slices from embryonic rats. In ester-loaded cells, bath-applied glutamate (3 mu M to 1 mM) evoked a [Ca2+](i) increase by up to 250 nM that was abolished by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) plus 2-amino-5-phosphonovalerate (APV). CNQX or APV alone reduced the response by 82 and 25%, respectively. The glutamatergic agonists kainate (KA), quisqualate (QUI), and S-alpha-amino-3-hydroxy-5-methyl-4-isoxalone (S-AMPA) evoked a similar [Ca2+](i) transient as glutamate. N-methyl-D-aspartate (NMDA) was only effective to increase [Ca2+](i) in Mg2+-free saline, whereas [1S,3R]-1-aminocyclopentane-1,3-dicarboxylic acid([1S,3R]ACPD) had no effect. The glutamate-induced [Ca2+](i) rise was suppressed in Ca2+-free superfusate. Depletion of Ca2+ stores with cyclopiazonic acid (CPA) did not affect the response. Thirty-six percent of the [Ca2+](i) increase in response to membrane depolarization induced by a 50 mM K+ solution persisted on combined application of the voltage-gated Ca2+ channel blockers nifedipine, omega-conotoxin-GVIA and omega-agatoxin-IVA. In fura-2 dialyzed motoneurons, the glutamate-induced [Ca2+](i) increase was attenuated by similar to 70% after changing from current to voltage clamp. Forty percent of the remaining [Ca2+], transient and 20% of the concomitant inward current of 0.3 nA were blocked by Joro spider toxin-3 (JSTX). The results show that voltage-gated Ca2+ channels, including a major portion of R-type channels, constitute the predominant component of glutamate-induced [Ca2+](i) rises. NMDA and Ca2+-permeable KA/AMPA receptors contribute about equally to the remaining component of the Ca2+ rise. The results substantiate previous assumptions that Ca2+ influx through JSTX-sensitive KA/AMPA receptors is involved in (trophic) signaling in developing motoneurons
Ciliary neurotrophic factor (CNTF): physiologische und pharmakologische Effekte in der Retina
No full textPrincipios tóxicos de Solanum malacoxylon Sendtner. I. Acción de fracción con solventes selectivos sobre el metabolismo fosfo-calcico y tejidos blandos del conejo.
No full textSe separaron seis fracciones químicamente diferentes de Solanum malacoxylon Sendtner por extracción con solventes selectivos, y se ensayó la acción de estas fracciones sobre el metabolismo del calcio y fósforos en conejos
PRINCIPIOS TOXICOS DE SOLANUM MALACOXYLON SENDTNER. l. ACCION DE FRACCIONES SEPARADAS POR EXTRACCION CON SOLVENTES SELECTIVOS SOBRE EL METABOLISMO FOSFO-CALCICO y TEJIDOS BLANDOS DEL CONEJO
No full textSe separaron seis fracciones químicamente diferentes de
hojas de Solanum malacoxylon Sendtner por extracción con solventes
selectivos, y se ensayó la acción de estas fracciones sobre el metabolismode
calcio y fósforo en conejos. Dos de estas fracciones elevaron
los niveles de fósforo inorgánico en sangre y produjeron calificaciones
en tejidos blandos; su composición indica que el efecto metabólico
debe atríbuirse a glicósidos, mono u oligosacáridos, aminoácidos u
oligopéptidos
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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