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  • 1
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: In the rat brain, the presynaptic 5-hydroxytrypt-amine (5-HT) autoreceptors located on 5-HT terminals correspond to the 5-HT1B subtype. The presence of a 5-HT receptor probably located on 5-HT nerve endings and modulating transmitter release in the human neocortex has been reported, but its detailed pharmacological characterization is not yet available. On the other hand, receptor binding and autoradiographic results indicate that the 5-HT1B receptor subtype is not present in the human brain. We, therefore, studied the modulation of the electrically evoked release of [3H]5-HT by various 5-HT receptor agonists and antagonists in preloaded slices of human neocortex obtained from 18 patients undergoing neurosurgery. The nonselective 5-HT1A/1B/1D receptor agonist 5-carboxamidotryptamine produced a potent inhibition (70% at 0.03 μM) of the electrically evoked release of [3H]5-HT which was blocked by 5-HT receptor antagonists with the following relative order of potency: methiothepin 〉 metergoline = methysergide 〉 propranolol. The selective 5-HT1A receptor agonist 8-hydroxy-2–(di-n-propylamino)tetralin at 0.1 μM did not modify the electrically evoked release of [3H]5-HT. The 5-MT1A/1B receptor agonist RU 24969 was 10 times more potent at inhibiting [3H]5-HT overflow in the rat frontal cortex than in the human neocortex. The potent 5-HT1B receptor antagonist cyanopindolol did not modify the 5-carboxamidotryptamine-induced inhibition of the electrically evoked release of [3H]5-HT in slices of the human neocortex, but produced by itself a small inhibition of [3H]5-HT overflow. The α2-adrenoceptor antagonist yohimbine, which possesses affinity for the 5-HT1D receptor subtype, decreased the release of [3H]5-HT, but only in the presence of the selective α2-adrenoceptor antagonist idazoxan, which by itself increased significantly [3H]5-HT overflow. Taken together, these results support the view that the 5-HT receptor modulating the electrically evoked release of [3H]5-HT in slices of the human neocortex could be of the 5-HT1D subtype. Moreover, preliminary results obtained with idazoxan confirm the existence of a presynaptic α2-adrenoceptor modulating the release of [3H]5-HT in the human neocortex. These α2-heteroreceptors could exert a tonic inhibitory modulation on 5-HT neurotransmission in the human neocortex.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Lasers in medical science 5 (1990), S. 241-244 
    ISSN: 1435-604X
    Schlagwort(e): CO2 laser ; Nd-YAG laser ; Endoscopic laser ; Stereotaxic laser surgery ; Intracranial tumours ; Intraorbital tumours ; Intraspinal tumours
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin , Physik , Technik allgemein
    Notizen: Abstract The early 1970s saw the birth of microscopic neurosurgery and the late 1970s the birth of laser neurosurgery. For more than 10 years now, laser radiations have been used during neurosurgical procedures: mostly for tumoral removal concerning essentially benign lesions. The reference laser has been and still is the CO2 laser, which has a limited penetration into CNS tissues. Until recently the Nd-YAG laser was used with its normal spectral transition, 1.064 μm. Because of its important diffusion in the CNS, it cannot be widely used except for shrinking large vascularized tumours such as meningiomas. The technological evolution has brought the laser specialists—physicists, medical doctors and surgeons—new concepts and new wavelengths which will progressively broaden laser applications and surgical procedures towards greater effectiveness, security and simplification. Holmium-YAG (2.1 μm), Erbium-YAG (2.9 μm) or long Nd-YAG wavelengths (1.44 or 1.32 μm) have been studied by different teams. The 1.32 μm Nd-YAG transition has been clinically used for about 2 years by a few neurosurgical teams (Beck in Munich, Roux in Paris, and more recently Lombard and Fasano in Torino, Ascher in Gratz). Laser radiations can be useful essentially during the removal of benign tumours, mostly if they are well vascularized and placed near functional structures such as the brain stem, the cranial nerves, the spinal cord: the CO2 laser is most efficient for vaporization; 1.06 Nd-YAG is effective for coagulation; 1.32 Nd-YAG provides very satisfactory photoevaporation effects if used with a superpulsed emission, and/or with a focusing handpiece, it also has good haemostatic properties with a c.w. output. The development of new optic fibre conducted wavelengths appears to be a possible answer to new requisites which should lead to the development of endoscopic neurosurgery (intraventricular tumours, discal herniations) and sterotaxic laser surgery (deep-seated intra-cerebral lesions).
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 0942-0940
    Schlagwort(e): 1.32 Nd-YAG Laser ; 1.06 Nd-YAG Laser ; stereotaxy ; endoscopic neurosurgery ; tumour removal
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The authors present their clinical experience with 1.32 μm NdYAG Laser. After a series of experimental studies which demonstrated the adaptability of such a wavelength to central nervous surgery, they used such a Laser during current neurosurgical procedures. The MC 2100 unit combines two wavelengths 1.32 μm and 1.06 μm, and two emission modes: continuous wave (c.w.) and pulsed. This Laser has been used during 70 procedures: 54 supra-tentorial, 8 infra-tentorial, 5 intra-spinal, 3 intra-orbital. 600 μm and 400 μm fibers were preferred in most cases, either with a telescopic light handpiece or-less often—with a focussing handpiece. The quality of vaporization—close to that of CO2 Laser—and of haemostasis —close to that of 1.06 μm Nd-YAG Laser—makes this 1.32 μm wavelength very suitable for neurosurgery. The manoeuverability due to the optic fibers is most interesting. Furthermore, such a Laser should have in the near future large applications in stereotactic and/ or endoscopic neurosurgery.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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