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Biomedical subjects

H Iida

Publications and source records attributed to H Iida.

At least 469 records · Page 26Linked to original sources
PubMed1987

Differences in vasodilating action between ketanserin, a 5-HT2-serotonergic receptor antagonist, and terazosin, an alpha 1-adrenoceptor antagonist, in anesthetized rabbits.

It has not yet been demonstrated clearly whether the antihypertensive action of ketanserin is due to 5-hydroxytryptamine type-2 (5-HT2)-serotonergic receptor blockade or to alpha 1-adrenergic receptor blockade. The present study was performed to evaluate in vivo the antihypertensive action of ketanserin in comparison with that of terazosin, a selective alpha 1-adrenoceptor antagonist. The changes of renal blood flow (RBF) after intrarenal injection of phenylephrine, 5-HT, or angiotensin II were measured in anesthetized rabbits. RBF responses induced by these vasoconstrictors with or without pretreatment with ketanserin (0.2, 1.0, and 5.0 mg/kg, i.v.) or terazosin (0.04, 0.2, and 1.0 mg/kg, i.v.) were examined. Following intrarenal injection, RBF decreased by 20.8%, 22.7%, and 23.0% respectively, without ketanserin and also decreased by 21.0%, 21.6%, and 24.4%, respectively, without terazosin. Following pretreatment with a small dose of ketanserin or terazosin, the vasoconstricting effects of phenylephrine were attenuated by 20% or 62% (delta% changes in RBF), respectively. The effects of 5-HT on RBF responsiveness were blocked by ketanserin in a dose-dependent manner. Ketanserin did not modify the RBF responses to angiotensin II. These findings indicate that the antihypertensive effect of ketanserin, to a certain extent, depends on the blockade of the 5-HT2-serotonergic receptor in addition to that of the alpha 1-adrenoceptor, whereas the renin-angiotensin system is not involved in the hypotensive effects of ketanserin.

Animals↗
PubMed1987

Surgical treatment of symptomatic atlantoaxial subluxation in Down's syndrome.

Six cases of relatively uncommon symptomatic atlantoaxial subluxation in Down's syndrome were treated surgically. In all cases, various congenital osseous anomalies were found. Marked myelopathy was noted in four cases of ossiculum terminale and mild myelopathy in one case of anteroposterior spondyloschisis. Five cases were treated successfully with posterior arthrodesis of C1 to C2 and one from the occiput to C2. Excellent bony union and overall improvement in the patients' symptoms was achieved, with a follow-up period ranging from 11 months to three years and nine months. In cases of symptomatic atlantoaxial subluxation of Down's syndrome, where the spinal cord is at risk, early surgical stabilization is the treatment of choice.

Adolescent↗
PubMed1987

[Cerebral blood flow measurement using H2(15)O intravenous injection and positron emission tomography: description of implementation and applications to cerebrovascular reactivity measurement].

The method for cerebral blood flow (CBF) measurement using an H215O intravenous injection and positron emission tomography (PET) was implemented, examined and applied to measure cerebrovascular reactivity to PaCO2(VRCO2) and to MABP (VRBP) in normal brain and in ischemic brain. Immediately after bolus intravenous injection of 30-40 mCi H2(15)O, a time-activity curve of H2(15)O concentration in the arterial blood and in the brain were measured for 60 sec by a beta detector and a PET, respectively. The PET was HEADTOME III and measured five planes. CBF was determined by the table-look up method based on the autoradiographic principle. Six volunteers were studied to examine region of VRCO2, and a moyamoya patient and a stroke patient with a bilateral-intracarotid circulation defect were studied to examine VRCO2 and VRBP in ischemic brain. The studies were carried out so as to be followed two or three H2(15)O CBF measurements with changing PaCO2 or MABP after control study at rest condition. In addition, prior to the H2(15)O study O15 gas steady state study was performed on all subjects. Validity of the method examined by simulation studies showed 3% error per 1 sec time shift of the artery curve for 60 sec PET scan duration and the error was rapidly increased to the shorter scan duration. Inhomogeneity of a brain tissue gave mild under-estimation by 5% for 60 sec PET scan duration. VRCO2 in normal brain was revealed to be almost uniform except that the infratentorium area showed a slight higher VRCO2 than the supratentorium area. The ischemic brain showed a negative correlation between VRCO2 and oxygen extraction fraction (OEF), and a positive correlation between VRBP and OEF.

Autoradiography↗
PubMed1987

Effect of the anticomplementary agent, K-76 monocarboxylic acid, on experimental immune complex glomerulonephritis in rats.

We examined the effect of the anticomplementary agent K-76 monocarboxylic acid (K-76COOH), which is known to inhibit C5 activity, on immune complex glomerulonephritis in rats. Bovine serum albumin (BSA) nephritis was induced in rats by subcutaneous immunization and daily intravenous administration of BSA. K-76COOH (30 mg/kg) was administered intraperitoneally twice daily for 4 weeks. It was shown that K-76COOH would significantly reduce the development of proteinuria in the early stage of BSA nephritis, but it failed to suppress proteinuria in the late stage. There was no significant difference in glomerular changes between treated animals and non-treated controls. These findings suggest that C5, and the terminal complement components may play a significant role in protein excretion in the early stage of immune complex glomerulonephritis.

Animals↗
PubMed1987

[Regional myocardial blood flow quantitatively measured using O-15 water and dynamic positron emission tomography].

This study was performed to measure regional myocardial blood flow (MBF) quantitatively using dynamic positron emission tomography (PET) and O-15 water. The subjects consisted of two normal volunteers, four patients with normal coronary angiograms (CAG), two patients with angina pectoris (3-vessel disease) and three patients with myocardial infarction. O-15 water (15-20 mCi) was injected via the cubital vein in a bolus, and dynamic PET was performed. MBF was calculated according to the method of Iida. The region of interest (ROI) was selected on the left ventricular wall (septum, anterior and lateral walls) and MBF was calculated in each ROI. In normal volunteers, MBF was 1.07 to 1.17 ml/g/min. It was 0.96 to 1.02 ml/g/min in patients with normal CAG, and 0.53 to 0.64 ml/g/min in patients with angina pectoris in the ischemic area. In patients with myocardial infarction, MBF was so diminished in the infarcted area as detected by 2-DE or ECG that the absolute value was almost 0 ml/g/min. In patients with angina pectoris, there was no definite defect on the MBF image, but we could estimate the severity of coronary stenosis by quantifying the MBF. The clinical advantages of this method include estimation of the severity of coronary arterial stenosis in the resting state.

Adult↗
PubMed1986

Effects of cytochalasins and colchicine on the accumulation and retention of daunomycin and vincristine in drug resistant tumor cells.

Cytochalasin B and D enhanced vincristine (VCR) and daunomycin (DAU) accumulation in tumor cells, especially in VCR- and DAU-resistant cell lines. The effect of cytochalasin B, and to a lesser extent cytochalasin D, was almost equivalent to that observed for verapamil, a calcium channel blocker which has been reported to enhance drug accumulation in tumor cells. Cytochalasin B was most effective in VCR- and DAU-sensitive cells; however, the effect in resistant cells was less than that observed for verapamil, suggesting a different mode of action between these drugs in sensitive and resistant cells. Enhanced accumulation of VCR and DAU by cytochalasins was mediated by the inhibition of outward transport of VCR and DAU from tumor cells. Colchicine had no effect on VCR and DAU accumulation. Cytochalasins, especially cytochalasin D is a specific inhibitor of microfilament assembly in cells. These results indicate that the cellular microfilament system plays a prominent role in drug transport of tumor cells, and that an intact microtubular system is less involved.

Animals↗