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Endogenous Mechanism (endogenous + mechanism)

Distribution by Scientific Domains

Medical Sciences	40%
Life Sciences	40%

Selected Abstracts

Endogenous Mechanisms of Inhibition of Platelet Function

MICROCIRCULATION, Issue 3 2005
RICHARD C. JIN MA
ABSTRACT Platelets play an important role in coagulation, in maintenance of hemostasis, and in the pathophysiology of thrombotic diseases. In response to blood vessel injury, platelets accumulate at the site, recruit other platelets, promote clotting, and form a hemostatic plug to prevent hemorrhage. By contrast, several inhibitory mechanisms modulate platelet function and act in a synergistic manner to prevent pathologic thrombus formation. This review focuses on the principal endogenous inhibitors of platelet function and the central role of the normal endothelium in these inhibitory processes. The main endothelium-derived platelet inhibitors include nitric oxide, prostacyclin, and Ecto-ADPase/CD39/NTPDase. Each of these factors is discussed in turn, and the specific mechanisms by which they inhibit platelet function are reviewed. [source]

Ecological implications of plants' ability to tell the time

ECOLOGY LETTERS, Issue 6 2009
Víctor Resco
Abstract The circadian clock (the endogenous mechanism that anticipates diurnal cycles) acts as a central coordinator of plant activity. At the molecular and organism level, it regulates key traits for plant fitness, including seed germination, gas exchange, growth and flowering, among others. In this article, we explore current evidence on the effect of the clock for the scales of interest to ecologists. We begin by synthesizing available knowledge on the effect of the clock on biosphere,atmosphere interactions and observe that, at least in the systems where it has been tested, the clock regulates gas exchange from the leaf to the ecosystem level, and we discuss its implications for estimates of the carbon balance. Then, we analyse whether incorporating the action of the clock may help in elucidating the effects of climate change on plant distributions. Circadian rhythms are involved in regulating the range of temperatures a species can survive and affects plant interactions. Finally, we review the involvement of the clock in key phenological events, such as flowering time and seed germination. Because the clock may act as a common mechanism affecting many of the diverse branches of ecology, our ultimate goal is to stimulate further research into this pressing, yet unexplored, topic. [source]

Anoxia,ischemia: A mechanism of seizure termination in ictal asystole

EPILEPSIA, Issue 1 2010
Stephan U. Schuele
Summary Cerebral anoxia,ischemia (CAI) is a potent inhibitor of cerebral hyperactivity and a potential mechanism of seizure self-termination. Prolonged ictal asystole (IA) invariably leads to CAI and has been implicated as a potential cause of sudden unexplained death in epilepsy (SUDEP). IA was seen in eight consecutive patients (0.12% of all patients monitored). Ten of their seizures with IA had evidence of CAI on electroencephalography (EEG), manifested by bilateral hypersynchronous slowing (BHS), and were compared to 18 seizures without signs of CAI. The ictal EEG pattern resolved in all 10 CAI events with onset of the BHS. The period from IA onset to seizure end was reduced in events with BHS compared to events without BHS (10.5 s vs. 28.3 s, respectively; p = 0.005), and the total seizure duration tended to be shorter. Anoxia,ischemia as a result of IA may represent an effective endogenous mechanism for seizure termination and may explain why the hearts of patients with ictal asystole reported to date in the literature resumed beating spontaneously. [source]

Neuropeptide Y delays hippocampal kindling in the rat

HIPPOCAMPUS, Issue 5 2003
Sophie Reibel
Abstract Chronic intrahippocampal infusion of the neurotrophin brain-derived neurotrophic factor (BDNF) has been shown to delay kindling epileptogenesis in the rat and several lines of evidence suggest that neuropeptide Y could mediate these inhibitory effects. Chronic infusion of BDNF leads to a sustained overexpression of neuropeptide Y in the hippocampus, which follows a time course similar to that of the suppressive effects of BDNF on kindling. In vivo, acute applications of neuropeptide Y or agonists of its receptors exert anticonvulsant properties, especially on seizures of hippocampal origin. In this study, we examined how chronic infusion of this neuropeptide in the hippocampus affected kindling epileptogenesis. A 7-day continuous infusion of neuropeptide Y in the hippocampus delayed the progression of hippocampal kindling in the rat, whereas anti-neuropeptide Y immunoglobulins had an aggravating effect. These results show that neuropeptide Y exerts anti-epileptogenic properties on seizures originating within the hippocampus and lend support to the hypothesis that BDNF delays kindling at least in part through upregulation of this neuropeptide. They also suggest that the seizure-induced upregulation of neuropeptide Y constitutes an endogenous mechanism counteracting excessive hippocampal excitability. Hippocampus 2003;13:557,560. © 2003 Wiley-Liss, Inc. [source]

Tissue Engineering Strategies Designed to Realize the Endogenous Regenerative Potential of Peripheral Nerves

ADVANCED MATERIALS, Issue 46 2009
Vivek Mukhatyar
Abstract http://doi.wiley.com/10.1002/adma.v21:32/33 Bridging peripheral nerve gaps without the use of autografts has significant clinical importance. But in order to rationally design novel scaffolds, a good understanding of the nerve regeneration process is vital. Appropriate amount of structural and chemical cues are required to stimulate the endogenous mechanisms of repair and functional recovery. Synthetic and natural materials present various opportunities to induce the growth of supporting cells as well as promote axon regeneration. An overview of tissue engineering strategies currently being explored that stimulate the different steps of the regenerative sequence is presented. [source]