Home About us Contact
|
Home About us Contact | ||
|
|
||
Active Mechanism (active + mechanism)
Selected AbstractsReduced saccadic resilience and impaired saccadic adaptation due to cerebellar diseaseEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2008Heidrun Golla Abstract The term short-term saccadic adaptation (STSA) captures our ability to unconsciously move the endpoint of a saccade to the final position of a visual target that has jumped to a new location during the saccade. STSA depends on the integrity of the cerebellar vermis. We tested the hypothesis that STSA reflects the working of a cerebellar mechanism needed to avoid ,fatigue', a gradual drop in saccade amplitude during a long series of stereotypic saccades. To this end we compared the kinematics of saccades of 14 patients suffering from different forms of cerebellar disease with those of controls in two tests of STSA and a test of saccadic resilience. Controls showed an increase in saccade amplitude (SA) for outward adaptation, prompted by outward target shifts, due to an increase in saccade duration (SD) in the face of constant peak velocity (PV). The decrease in SA due to inward adaptation was, contrariwise, accompanied by a drop in PV and SD. Whereas patients with intact vermis did not differ from controls, those with vermal pathology lacked outward adaptation: SD remained constant, as did SA and PV. In contrast, vermal patients demonstrated a significant decrease in SA, paralleled by a decrease in PV but mostly unaltered SD in the inward adaptation experiment as well as in the resilience test. These findings support the notion that inward adaptation is at least partially based on uncompensated fatigue. On the other hand, outward adaptation reflects an active mechanism for the compensation of fatigue, residing in the cerebellum. [source] Contribution of exofacial thiol groups in the reducing activity of Lactococcus lactisFEBS JOURNAL, Issue 10 2010D. Michelon Lactococcus lactis can decrease the redox potential at pH 7 (Eh7) from 200 to ,200 mV in oxygen free Man,Rogosa,Sharpe media. Neither the consumption of oxidizing compounds or the release of reducing compounds during lactic acid fermentation were involved in the decrease in Eh7 by the bacteria. Thiol groups located on the bacterial cell surface appear to be the main components that are able to establish a greater exchange current between the Pt electrode and the bacteria. After the final Eh7 (,200 mV) was reached, only thiol-reactive reagents could restore the initial Eh7 value. Inhibition of the proton motive force showed no effect on maintaining the final Eh7 value. These results suggest that maintaining the exofacial thiol (,SH) groups in a reduced state does not depend on an active mechanism. Thiol groups appear to be displayed by membrane proteins or cell wall-bound proteins and may participate in protecting cells against oxidative stress. [source] Contribution of a mitochondrial pathway to excitotoxic neuronal necrosisJOURNAL OF NEUROSCIENCE RESEARCH, Issue 9 2009Dae-Won Seo Abstract It is traditionally thought that excitotoxic necrosis is a passive mechanism that does not require the activation of a cell death program. In this study, we examined the contribution of the cytochrome c-dependent mitochondrial death pathway to excitotoxic neuronal necrosis, induced by exposing cultured cortical neurons to 1 mM glutamate for 6 hr and blocked by the NMDA antagonist, dizocilpine. Glutamate treatment induced early cytochrome c release, followed by activation of caspase-9 and caspase-3. Preincubation with the caspase-9 inhibitor z-LEHD-fmk, the caspase-3 inhibitor z-DEVD-fmk, or the specific pan-caspase inhibitor Q-VD-oph decreased the percentage of propidium iodide-positive neurons (52.5% ± 3.1%, 39.4% ± 3.5%, 44.6% ± 3%, respectively, vs. 65% ± 3% in glutamate + vehicle). EM studies showed mitochondrial release of cytochrome c in neurons in the early stages of necrosis and cleaved caspase-3 immunoreactivity in morphologically necrotic neurons. These results suggest that an active mechanism contributes to the demise of a subpopulation of excitotoxic necrotic neurons. © 2009 Wiley-Liss, Inc. [source] The protective action of scutellarin against immunological liver injury induced by concanavalin A and its effect on pro-inflammatory cytokines in miceJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 1 2007Zheng Huai Tan Scutellarin is a natural compound from a Chinese herb. The purpose of this paper was to study the protective effect of scutellarin on concanavalin A (Con A)-induced immunological liver injury and its effect on liver nuclear factor ,B (NF-,B), tumor necrosis factor , (TNF-,), interferon , (IFN-,), and inducible nitric oxide synthase (iNOS) expression in mice. Mouse liver injury was produced by injection of Con A 25 mg kg,1 via the tail vein. Scutellarin 50 or 100 mg kg,1 was peritoneally administered to mice 9 or 1 h before injection of Con A. The levels of serum alanine aminotransferase (ALT) and asparatate aminotransferase (AST), NO2,/NO3, and TNF - , were determined with biochemical kits, and ELISA using Quantikine Mouse TNF-, kit according the manufacturer's instructions. Liver lesions were examined by light microscope. The expression of TNF-,, IFN-,, iNOS and Fas mRNA in the livers was detected by RT-PCR; and the expression of c-Fos, c-Jun, iNOS and I,B proteins was measured by Western Blotting. As a result, pretreatment with scutellarin 100 mg kg,1 significantly decreased the serum ALT, AST, NO2,/NO3,and TNF-, levels, and also reduced liver lesions induced by Con A. Scutellarin 100 mg kg,1 down-regulated expression of TNF-, and iNOS mRNA, and c-Fos, c-Jun and iNOS protein, while scutellarin enhanced the degradation of I,B, in the livers of mice injected with Con A. The results suggest that scutellarin has a protective action against Con A-induced liver injury in mice, and its active mechanism may be related to the inhibition of the NF-,B-TNF-,-iNOS transduction pathway. [source] | ||||||||||