RESUMO
A central question in the study of amorphous materials is the extent to which they are ordered. When the crystalline intermetallic R-Al(5)Li(3)Cu is compressed to 23.2 gigapascals at ambient temperature, an amorphous phase is produced whose order can be described as defects in a curved-space crystal. This result supports a structural relation between quasi-crystals and amorphous metals based on icosahedral ordering. This result also shows that a metallic crystal can be made amorphous by compression.
RESUMO
This two-part study investigated the topical treatment of vasospasm in the tail arteries of rats. In part A, an epinephrine-induced model of vasospasm was used to study a variety of vasodilating agents with actions on at least five different sites in the contractile mechanism of the vascular smooth-muscle cell. The most effective commercially available agents evaluated in this part of the study appeared to be 20% lidocaine and Thorazine (25 mg/ml). In part B, a model was established in which epinephrine-induced vasoconstriction was found to significantly impair anastomotic patency. Thorazine was shown to improve the patency rate of vessels in this setting, and it was found to be superior to 20% lidocaine in improving anastomotic patency.
Assuntos
Espasmo/tratamento farmacológico , Vasodilatadores/administração & dosagem , Administração Tópica , Animais , Clorpromazina/administração & dosagem , Modelos Animais de Doenças , Avaliação de Medicamentos , Epinefrina , Lidocaína/administração & dosagem , Masculino , Contração Muscular/efeitos dos fármacos , Músculo Liso Vascular/efeitos dos fármacos , Ratos , Ratos Endogâmicos , Espasmo/induzido quimicamente , Cauda/irrigação sanguínea , Fatores de Tempo , Doenças Vasculares/induzido quimicamente , Doenças Vasculares/tratamento farmacológico , Vasoconstrição/efeitos dos fármacosRESUMO
Characterization and resolution of microvascular spasm were investigated in 170 studies with the use of tail or femoral arteries of the rat. Topical epinephrine reliably produced vasospasm and topical vasodilators which included 2% and 20% lidocaine (Xylocaine) and 0.75% bupivacaine (Marcaine) were applied to resolve the vasoconstriction. Extensive vessel dissection was necessary to obtain significant resolution of vasospasm, and adventitial stripping was associated with even more impressive results. Local anesthetics appear to have a concentration dependent ability to resolve vasospasm, and 20% Xylocaine is the most effective agent yet studied.