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Biomedical subjects

T Ando

Publications and source records attributed to T Ando.

At least 577 records · Page 32Linked to original sources
PubMed1986

The mechanism of the hypotensive effect of captopril (converting enzyme inhibitor) with special reference to the kallikrein-kinin and renin-angiotensin systems.

In order to clarify the mechanism of the hypotensive action of captopril, the acute and chronic effects of this drug on the kallikrein-kinin and renin-angiotensin systems were investigated respectively in 14 and 19 patients with hypertension. To determine the acute effect, a dose of 50 mg of captopril was administered once orally. For the chronic effect, 75-300 mg of the drug was administered daily for 14 days. In observations of the acute effect, blood pressure decreased significantly at 30 min. and maximally at 60-180 min. after administration with no change in heart rate. Significant increases in blood kinin levels and plasma renin activity (PRA), and a decrease in plasma angiotensin II levels were also observed. A marked augmentation was also found in urinary kinin excretion, but not in urinary kallikrein excretion. Moreover, the changes in blood pressure significantly correlated negatively with basal PRA, basal plasma angiotensin II and the changes in blood kinin levels, and positively with the changes in plasma angiotensin II. In our study of the chronic effect of captopril, similar changes in blood kinin levels, PRA, plasma angiotensin II levels, blood pressure and heart rate to the acute effect study were observed. Significant correlations of the changes in blood pressure were found negatively with basal PRA, basal plasma angiotensin II levels and the changes in blood kinin levels and positively with the changes in plasma angiotensin II levels. In addition, significant increases in urine volume and urinary sodium excretion occurred following administration of captopril for 14 days, and both increases negatively correlated with the changes in blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Localization of renal kallikrein-kinin system components in the kidney.

In a study using a stop-flow technique in dog kidney, the existence of kallikrein and kinin was recognized in distal tubules. The presence of kininase I was seen in both distal and proximal tubules, and also partly in the distal tubules. The presence of kininase II in the distal tubules was again confirmed by pretreatment with SQ14225. No evidence of kinin formation, however, was obtained in the proximal nephrons in stop-flow method. From these results, it was suggested that kininase I and II localized in proximal tubules may destroy the kinin filtered from glomeruli at the proximal level, while kallikrein and kininogen and also kininase I and II in the distal tubules may regulate the activity of the renal kallikrein-kinin system in the distal nephrons.

Animals↗
PubMed1986

FR-900452, a specific antagonist of platelet activating factor (PAF) produced by Streptomyces phaeofaciens. I. Taxonomy, fermentation, isolation, and physico-chemical and biological characteristics.

A PAF antagonist, designated as FR-900452, was isolated from fermentation products of Streptomyces phaeofaciens and the molecular formula was determined as C22H25N3O3S. The compound inhibited PAF-induced rabbit platelet aggregation with an IC50 of 3.7 X 10(-7)M, but was much less active against collagen-, arachidonic acid- or ADP-induced aggregation (IC50; 6.4 X 10(-5), greater than 10(-4) or greater than 10(-4)M, respectively).

Adenosine Diphosphate↗
PubMed1986

[Pineocytoma--a case report].

A report on a rare case of pineocytoma is presented. A 27-year-old woman visited our clinic because of a 3-month history of intermittent headaches and nausea. A CT scan revealed the presence of a marked obstructive hydrocephalus and mass without any contrast enhancement in the pineal region. Immediately, V-P shunting was performed and resulted in relief of all symptoms. Ventriculography showed a complete occlusion at the aqueductus Sylvii and filling defect at the posterior part of the 3rd ventricle. The patient was operated on in the prone position via infratentorial supracerebellar approach by suboccipital craniectomy on November 9, 1982. A grayish red-colored, well-defined solid tumor located at the pineal region was removed partially. The histopathological appearance of this tumor resembled the pattern of the normal pineal gland. Many cells exhibited a polar form, eosinophilic cytoplasm with the process often being directed toward a blood vessel. The cells around the central areas occupied by pale eosinophilic material were arranged like a "rosette". Combined chemo-radiotherapy was carried out after surgery. That is, a total dose of 4,825 rads to the whole brain was irradiated, and ACNU 140 mg and VCR 6 mg in total were administered intravenously and intermittently. After irradiation therapy, the tumor increased in size producing a ring-like enhancement effect as shown on repeated CT scans. During this time, she started to complain of blurred vision with Parinaud's sign. A second operation via interhemispheric approach by right parietal craniotomy was undergone, and the tumor was partially resected again on March 29, 1983.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Absorption, distribution and excretion of 2,4-diamino-6-(2,5-dichlorophenyl)-s-triazine maleate in rats, dogs and monkeys.

Absorption, distribution and excretion of 2,4-diamino-6-(2,5-dichlorophenyl)-s-triazine maleate (MN-1695) were studied in rats, dogs and monkeys after administration of [14C]-MN-1695. MN-1695 was found to be well absorbed from the small intestine after oral administration in all species examined. Plasma level of unchanged MN-1695 reached a maximum at 1 to 4 h after oral administration of [14C]-MN-1695 in rats, dogs and monkeys. The mean elimination half-life of unchanged MN-1695 from plasma was about 3, 4 and 50 h in rats, dogs and monkeys, respectively. Tissue levels of radioactivity after oral administration of [14C]-MN-1695 in rats indicated that [14C]-MN-1695 was distributed throughout the body and the radioactivity in tissues disappeared with a rate similar to that in plasma. A stomach autoradiogram after intravenous administration of [14C]-MN-1695 in the rat revealed the radioactivity localized in the gastric mucosa where MN-1695 was assumed to exert its pharmacological activity. In pregnant rats, [14C]-MN-1695 was distributed to the fetus with levels similar to maternal blood levels. After oral administration of [14C]-MN-1695 in rats, 39 to 46% of the dose was excreted into the urine and 50 to 63% of the dose into the feces, within 96 h. In dogs, about 40% of the dose was excreted into the urine and about 50% of the dose into the feces, within 6 days after oral administration. In monkeys, within 14 days after oral administration, about 60 and 30% of the dose were excreted into the urine and feces, respectively, and the main excretion route was the urine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Metabolism of 2,4-diamino-6-(2,5-dichlorophenyl)-s-triazine maleate in rats, guinea pigs, dogs and monkeys.

The metabolism of 2,4-diamino-6-(2,5-dichlorophenyl)-s-triazine maleate (MN-1695) was studied in rats, guinea pigs, dogs and monkeys. MN-1695 was metabolized to more than 8 metabolites after oral administration in a dose of 3.1 mg/kg in rats. These metabolites were isolated from the urine and characterized by cochromatography with reference compounds, mass spectrometry and other instrumental analysis. The main metabolite in the urine was MN-1695 X m-OH, which was excreted as a conjugate, in rats and guinea pigs, and MN-1695 X N-oxide in dogs. In monkeys, MN-1695 X m-OH (free and conjugate) and MN-1695 X N-oxide predominated in the urine, although MN-1695 was not extensively metabolized. In rats, over 90% of the radioactivity excreted into the bile consisted of the polar metabolites. The major metabolic pathways of MN-1695 found in various animal species involved the hydroxylation at the positions of 3 and 4 of the aromatic ring and the N-oxidation at the position of 3 of the s-triazine ring. In addition, the sulfur-containing metabolites were detected in all species examined.

Animals↗
PubMed1985

Monoclonal antibodies with specific effects on partial activities of recA protein of Escherichia coli.

recA protein of Escherichia coli promotes a wide variety of DNA reactions in vitro. Specific effectors of recA protein should be very useful in elucidating the mechanisms of these complex reactions. Six mouse hybridoma clones that secreted class G immunoglobulins specific to recA protein were obtained in three cell-fusion experiments. Five IgGs were purified by affinity chromatography. These monoclonal antibodies were characterized by examining their effects on the single-stranded DNA-dependent ATPase activity, negatively superhelical double-stranded DNA-dependent ATPase activity, and an activity in pairing negatively superhelical closed circular double-stranded DNA and homologous single-stranded DNA-fragments to form D-loops. These IgGs inhibited all, some, or one of these three activities, and from the spectra of their inhibitory effects they were classified into four groups. This classification suggests that each of the monoclonal antibodies binds to one of at least four antigenic determinants on recA protein and specifically inactivates one or more of the active centers on the protein. These monoclonal antibodies will be useful in analyzing the complex reactions promoted by recA protein.

Adenosine Triphosphatases↗
PubMed1985

The rate of MgADP binding to and dissociation from acto-S1.

The rate of binding and dissociation of MgADP from its ternary complex with actin and S1 was measured by following the extent to which fixed concentrations of MgADP slow down MgATP-induced dissociation of acto-S1. The solution of the equations describing this process shows that at any MgADP concentration the apparent rate of acto-S1 dissociation should be proportional to a square root of the equilibrium constant for MgADP dissociation and to MgATP concentration. By measuring the apparent rate of acto-S1 dissociation as a function of MgATP concentration, the rate of MgADP binding and dissociation were determined as 5 X 10(6) M-1 X s-1 and 1400 s-1, respectively. These rates were unchanged by modification of SH1 thiol of S1 by a variety of fluorescence and spin-labels, but dissociation rate was drastically reduced when SH1 was labelled with 5-iodoacetamidofluorescein.

Actins↗
PubMed1985

Skeletal muscle myosin subfragment-1 induces bundle formation by actin filaments.

As is well known, the light scattering intensity of F-actin solutions increases immediately upon formation of the rigor complex with subfragment-1 (S-1). We have found that after the initial rise in scattering, there is a further gradual increase in scattering (we call it "super-opalescence"). Fluorescence and electron microscopic observations of acto-S-1 solutions showed that super-opalescence results from formation of actin filament bundles once S-1 binds to F-actin. The actin bundles possessed transverse stripes with a periodicity of about 350 A, which suggested that in the bundles actin filaments are arranged in parallel register. The rate of the initial process of bundle formation (i.e. side-by-side dimerization) could be approximately estimated by measuring the initial rate of super-opalescence (V0). V0 had a maximum (V0m) at a molar ratio of S-1 to actin of 1;6-1;7, regardless of the actin concentration, pH (6-8.5), Mg2+ concentration (up to 5 mM), or ionic strength (up to 0.3 M KC1). Lower pH, higher Mg2+ concentration, and higher ionic strength increased V0m; V0 was proportional to the square of the actin concentration, regardless of the solution conditions.

Actins↗
PubMed1985

Prevention of rebleeding after operation for subarachnoid hemorrhage of unknown cause.

This study is presented to promote prophylactic operation to prevent rebleeding after subarachnoid hemorrhage (SAH) of unknown cause. Twenty-two cases of nontraumatic SAH of unknown cause of a total of 254 cases of SAH treated during a 5-year period (1980-1984) were available for this study. A follow-up study (4 to 61 months after treatment; median, 43 months) revealed a 4.5% mortality rate. Four patients chosen from among the 22 SAH cases underwent prophylactic operation. The decision to operate was based on repeated angiography showing regional cerebral vasospasm corresponding to a limited hyperdense area on the computed tomographic scan at the time of the onset of SAH. Microsurgery revealed a minute protrusion (less than 2 mm in diameter) or thinning of the arterial wall with old hematoma of the surrounding brain in all 4 cases, and treatment required only coating of the abnormal site. All 4 patients are now fully recovered. Frequently, abnormal changes of such cerebral arteries as the anterior communicating artery, the internal carotid artery (C-1 and C-2), and the middle cerebral artery (M-1) may occur. Therefore, the authors emphasize the necessity of surgical treatment for specific cases of SAH with an unknown cause.

Adult↗