Biomedical subjects

Y Hirano

Publications and source records attributed to Y Hirano.

328 records · Page 19Linked to original sources

PubMedDate not supplied

Potassium channel-opening and vasorelaxant profiles of a novel compound YM099 in rat isolated portal vein and rabbit isolated aorta.

The potassium channel-opening and vasorelaxant profiles of YM099, a newly synthesized benzoxadiazol derivative K channel opener, were evaluated in vitro. In the rat isolated portal vein, YM099 and a benzopyran derivative K channel opener levcromakalim concentration-dependently inhibited the frequency of spontaneous rhythmic contractions, with IC50 values of 104 and 38 nM, respectively. In the rabbit isolated aorta, YM099 (10(-7)-3 x 10(-5) M) and levcromakalim (10(-7)-3 x 10(-5) M) also concentration-dependently relaxed the contractions induced by 20 mM KCl, but they were ineffective against the contractions induced by 50 mM KCl. These effects of YM099 and levcromakalim were competitively antagonized by a K channel blocker glibenclamide (10(-7)-3 x 10(-6) M). In the rabbit isolated aorta, YM099 (3 x 10(-8)-3 x 10(-6) M), but not the calcium antagonist nifedipine (10(-8)-3 x 10(-6) M), relaxed the contractions induced by norepinephrine (10(-6) M) or prostaglandin F2 alpha (3 x 10(-6) M). These vasorelaxant effects of YM099 were also antagonized by glibenclamide. In conclusion, YM099 is a potent vascular smooth muscle-relaxant agent and possesses a vasorelaxant effect different from that of nifedipine. These effects of YM099 may be mediated, like those of levcromakalim, by the opening of glibenclamide-sensitive K channels.

Animals↗

PubMedDate not supplied

[Diagnosis of ischemic heart disease by dipyridamole-stress two-dimensional echocardiography].

The diagnostic usefulness of dipyridamole-stress two-dimensional echocardiography was assessed in 82 patients consisting of 27 patients with angina pectoris, 42 with myocardial infarction, and 13 control subjects. Two-dimensional echocardiographic monitoring was performed during dipyridamole infusion: 0.56 mg/kg for 4 minutes, then discontinuation for 4 minutes, followed by a final infusion of 0.28 mg/kg for 2 minutes. The cumulative dose was 0.84 mg/kg. Worsening or fixed wall motion abnormality with unaffected baseline indicated a positive finding. All patients underwent coronary angiography. The sensitivity and specificity of dipyridamole-stress two-dimensional echocardiography for diagnosis of significant coronary artery stenosis (> or = 75%) were 84% (58/69) and 92% (12/13), respectively. The sensitivity of this method for the branches of the coronary artery was 85% for the left anterior descending artery, 80% for the right coronary artery, and 75% for the left circumflex artery. The sensitivity for single-, double-, triple-vessel disease was 75%, 81% and 100%, respectively. The sensitivity and specificity of the dipyridamole electrocardiogram (ST depression more than 0.1 mV) were 33% (23/69) and 77% (10/13), respectively. The appearance of dipyridamole-stress induced wall motion abnormality was significantly earlier than those of chest pain and ST segment depression. Side effects were observed in 43% (35/82) of patients, but were only mild and transient. Dipyridamole-stress two-dimensional echocardiography is the best method for detecting coronary artery stenosis and predicting the localization of lesion sites.

Aged↗

PubMedDate not supplied

Superselective angio-CT of brain tumors.

PURPOSE: To determine the efficacy of superselective angio-CT in the diagnosis of astrocytoma. METHODS: Nineteen patients with astrocytoma had superselective angio-CT before chemotherapeutic agents were administered via superselective intraarterial infusion. CT was performed after contrast material was delivered through a microcatheter, which had been advanced into the feeding arteries of the tumor. Superselective angio-CT scans were compared with digital subtraction angiograms, conventional contrast-enhanced CT scans, and contrast-enhanced T1-weighted MR images. RESULTS: Superselective angio-CT scans depicted contrast enhancement of the tumor in all of the patients and the medullary veins of the tumors in 32% of the patients. Digital subtraction angiograms showed tumor stains in 68% of the patients and the medullary veins in only 5%. Conventional CT scans and MR images showed contrast enhancement of the tumor in 89% of the patients. Superselective angio-CT scans confirmed the proper position of the catheter tip for the infusion of a chemotherapeutic agent. CONCLUSIONS: Superselective angio-CT can be used to depict contrast enhancement of tumors and the vascular structures that are characteristic of astrocytomas.

Adult↗

PubMedDate not supplied

Chemoembolization of maxillary tumors via the superficial temporal artery using a coaxial catheter system.

A preliminary experience of embolization of maxillary tumors via the superficial temporal artery using a coaxial catheter system is presented. Five patients with maxillary carcinoma were slated to undergo embolization before radical surgery. Embolization with carboplatine microcapsules was performed via the superficial temporal artery using a coaxial catheter system. Carboplatine microcapsules consisted of 60% (W/W) carboplatine core and 40% (W/W) ethylcellulose shell. Embolization was performed twice in three patients, three times in one patient, and once in one patient. The interval between embolizations was from one to three weeks. The total dose of carboplatine microcapsules given ranged from 100 to 230 mg. Responses to the treatment were determined by measurements of tumor reduction and increase in low attenuation areas of the tumor on postcontrast CT. Tumor reduction over 48% was achieved in four of five tumors. All the tumors showed an increased area of low attenuation in the tumor on the postcontrast CT after embolization. No significant complications occurred. This method makes it easy to superselectively repeat embolization.

Aged↗