Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The swimmeret system can be excited by perfusing the neuropeptide proctolin through the isolated ventral nerve cord of the crayfish. Previously silent preparations begin to generate a characteristic motor pattern, the swimmeret rhythm, in the nerves that innervate the swimmerets. The response to proctolin is dose dependent and reversible. The threshold concentration of proctolin perfused through the ventral artery is approximately 10(-8) M. The EC50 is 1.6 X 10(-6) M. 2. Proctolin-induced motor patterns have periods and phases similar to those of spontaneously generated motor patterns. The durations of the bursts of impulses in power-stroke motor neurons generated in the presence of proctolin are, however, significantly longer than those that occur during spontaneous activity. 3. DL-Octopamine inhibits the swimmeret system, both when the system is spontaneously active and when it has been excited by proctolin. The inhibition by octopamine is dose dependent and reversible. The threshold for inhibition is approximately 10(-6) M, and the EC50 is approximately 5 X 10(-5) M. 4. Octopamine's effect is mimicked by its agonists, synephrine and norepinephrine. Synephrine has a lower threshold concentration than does octopamine, but norepinephrine is much less effective than octopamine. 5. Octopamine's inhibition is partially blocked by an antagonist, phentolamine. 6. Phentolamine also blocks inhibition of the swimmeret system by inhibitory command interneurons. This block is dose dependent and can be partially overcome by stimulating the command interneurons at higher frequencies. 7. Perfusion with 11 other suspected crustacean neurotransmitters and transmitter analogues did not similarly excite or inhibit the swimmeret system, so we suggest that proctolin and octopamine are transmitters used by the neurons that normally control expression of the swimmeret rhythm.
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PMID:Modulation of the crayfish swimmeret rhythm by octopamine and the neuropeptide proctolin. 311 73

In response to concerns regarding the safety of ephedra-containing dietary supplements, manufacturers have marketed "ephedra-free" products. Many of these contain synephrine, a sympathomimetic amine from the plant Citrus aurantium. Synephrine is structurally similar to ephedrine and has vasoconstrictor properties. We describe a 38-year-old patient with ischemic stroke associated with an ephedra-free dietary supplement containing synephrine and caffeine. The patient presented with memory loss and unsteady gait after taking 1 or 2 capsules per day of a dietary supplement (Stacker 2 Ephedra-Free) for 1 week. He had no notable medical history or major atherosclerotic risk factors and took no other medications. Physical examination showed a mildly ataxic gait and substantial Impairment of both concentration and memory. Computed tomography and magnetic resonance Imaging of the brain showed subacute infarctions in the left thalamus and left cerebellum in the distribution of the vertebrobasilar circulation. Other causes of ischemic stroke were evaluated, and findings were unremarkable; a vasospastic origin was considered most likely. The patient was discharged with nearly complete resolution of symptoms. Synephrine, a sympathomimetic amine related to ephedrine, may be associated with Ischemic stroke. Consumers and clinicians need to be Informed about the potential risks of ephedra-free products.
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PMID:Ischemic stroke associated with use of an ephedra-free dietary supplement containing synephrine. 1581 93