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  • Artery  (1)
  • Keywords: Deposited light energy; Nitric oxide; Photochemical effect; Photocontraction; Photorelaxation; Thermal effect  (1)
  • Active oxygen
  • Springer  (2)
  • 2000-2004  (2)
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  • Springer  (2)
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  • 1
    ISSN: 1435-604X
    Keywords: Keywords: Deposited light energy; Nitric oxide; Photochemical effect; Photocontraction; Photorelaxation; Thermal effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract . Light induces various vascular tension changes, but these phenomena and their mechanisms remain controversial. We hypothesise that photocontraction results from the thermal effect, and that photorelaxation results from the non-thermal effect of photochemical nitric oxide generation. The isometric tension of a rat aortic ring was measured during laser light irradiation at various wavelengths with constant heat generation. Visible irradiation (458 nm, 514.5 nm) induced either photorelaxation (the tension increment was −20% of the contracted state induced by noradrenaline) or photocontraction (+7.8%); UV irradiation (351 nm) induced only photorelaxation (−41%), and near-IR irradiation (800 nm) produced only photocontraction (+11%). In the vascular tissue, photocontraction increased with deposited light energy, which was proportional to the temperature elevation. Simply heating the vascular tissue also resulted in vasocontraction. Photorelaxation by UV occurred even in the absence of endothelium, and was significantly reduced to 49% of control levels of photorelaxation by the guanylate cyclase inhibitor, methylene blue. Photorelaxation was not reduced by the nitric oxide synthetase inhibitors, N ω-monomethyl-l-arginine (l-NMMA) and N ω-nitro-l-arginine methyl ester (l-NAME). We conclude that photocontraction is produced by the thermal effect resulting from deposited light energy. Photorelaxation might be induced by endothelium-independent nitric oxide generation, which seems to result from the photochemical effect due to photon energy.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1920
    Keywords: Key words Angioplasty ; Endarterectomy ; carotid ; Artery ; internal carotid ; Restenosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The efficacy of repeated percutaneous transluminal angioplasty (PTA) and carotid endarterectomy (CEA) was examined in patients with restenosis after PTA for carotid stenosis. After percutaneous transluminal angioplasty (PTA) for 63 cases of internal carotid stenoses 13 cases of restenosis appeared. They were treated by PTA or carotid endarterectomy. The treatment was chosen by the patient after explanation of each treatment. We initially treated seven patients by repeat PTA and six by carotid endarterectomy. The degree of stenosis improved from 82 % to 30 % on average after repeated PTA. However, one patient in the PTA group had restenosis, and carotid endarterectomy was then performed. The other cases also had restenosis and were treated by PTA. The six cases treated by carotid endarterectomy were successfully treated without difficulty. The success rate of PTA was 5/7 (71 %) in the restenosis cases. Patients with a greater residual stenosis after initial PTA had significantly more frequent restenosis. Repeat PTA and CEA both appeared effective treatment for restenosis after initial PTA, although PTA had a restenosis rate similar to that of initial PTA.
    Type of Medium: Electronic Resource
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