Biomedical subjects
Publications and source records attributed to S Imai.
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Subacute toxicity of STO was carried out using Wistar rats. STO was administered intravenously at dose levels of 12.5, 50.0 and 200.0 mg/kg for 35 days. No influence on general symptom, body weight, food and water consumption and urinalysis were observed. In 200.0 mg/kg group, the hematological examination revealed anemia corresponding to the histological findings of the bone marrow. Biochemical analysis displayed the significant increase and/or decrease of enzyme values in 200.0 mg/kg group. Morphology showed the swelling, vacuolization and granuloma of the spleen, hepatic granuloma, the increase of reticulum cells and granuloma in the bone marrow. Embolism and thrombus were also found in the pulmonary and tail veins probably due to an artifact caused by the i.v. injection. The toxicity of the STO were observed only in 200.0 mg/kg group of both sexes and any remarkable change other than physical effects were found in other groups under the above dosage. Accordingly, the maximal no-effect level of the STO in Wistar rats was considered to be 50.0 mg/kg.
Cosynthesis in mixed culture and protoplast fusion of non-producing mutants of Streptomyces hygroscopicus which may produce biosynthetic intermediates of bialaphos (AMPBA) were studied. Non-producing mutants were obtained by mutagenesis with N-methyl-N'-nitro-N-nitrosoguanidine (NTG) treatment, and six stable non-producing mutants were used for cosynthesis and protoplast fusion studies. The biosynthetic block sites of the non-producers were consistent with studies of the biosynthetic pathway of AMPBA.
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Effects of beta-blockers on the blood pressure (BP), urinary output (V) and excretion of Na% (UNaV) and K+ (UKV) were studied in DOCA-saline hypertensive rats in comparison with those of a thiazide diuretic drug, penfluzide. Pindolol produced a hypotension at all infusion rates of Ringer's solution used and a decrease in V with a retention of Na+ and K+ at a low infusion rate. There was a parallel shift of Guyton's renal function curve back to the lower pressure ranges. Similar effects were observed with labetalol. Propranolol induced an increase in UKV at all infusion rates and had a diuretic action at a high infusion rate without producing a significant fall of BP. UKV tended to be increased after atenolol, with essentially no change in other parameters. A new beta-blocker with alpha-blocking action, K-351, produced a hypotension at intermediate and high infusion rates and an increase in UNaV (low infusion rate) and UKV (low and high rates). UKV tended to be increased with another new beta-blocker, N-696, with a fall of BP at high infusion rate. Penfluzide produced a significant decrease in BP at intermediate and high infusion rates and an increase in UKV at all infusion rates.
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In order to search into the mechanism of the relaxant effects of nicorandil, a new coronary vasodilator, on the dog coronary artery, the effects of this substance on the potassium contracture were studied, and compared with those of nitroglycerin and nifedipine. All the three substances induced a dose-related relaxation (nifedipine greater than nitroglycerin greater than nicorandil). However, the increase in La3+-resistant 45Ca uptake was inhibited only by nifedipine. In a calcium-free EGTA containing medium caffeine induced a phasic contraction in the fully-depolarized preparation. Nicorandil produced an inhibition of this contraction, while nitroglycerin and nifedipine did not. It was concluded that nicorandil differs from the so-called calcium antagonists in the mechanism of relaxant action on the coronary artery. It also differs from nitroglycerin in that it produced an inhibition of caffeine-induced contraction.
The SHN mouse strain, which has a high incidence of mammary cancer, developed by inbreeding and selection from Swiss stock mice by Dr. H. Nagasawa and co-workers (Meiji University, Tokyo, Japan), harbored an endogenous mammary tumor virus (MTV) responsible for a high frequency of mammary tumors early in life. The locus was called "Mtv-4" and was only comparable with Mtv-2 of the GR mouse strain in its inducing capacity of mammary cancer. Molecular hybridization with 32P-labeled MTV complementary DNA showed that the characteristic Mtv-2 bands of the GR strain were absent in the SHN strain.
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The incidence of choroid plexus papilloma is about 0.5% of all intracranial tumors, but choroid plexus papilloma in the third ventricle is rare. Fortuna reported 56 cases of choroid plexus papilloma of the third ventricle in 1979. Among them, the neoplasm of the third ventricle in the neonatal period was not found. This report is a case of choroid plexus papilloma of the third ventricle in the neonatal period. A 34 day-old female was admitted to our service with complaints of head enlargement, vomiting, and convulsive seizures on January 8, 1981. Enlarged head had been noticed by her family within the first two weeks. On admission, a marked congenital hydrocephalus was diagnosed by CT scan with symmetrical dilated ventricles and no abnormal high or low density area, and V-P shunt was performed on the next day. But several days later, she suffered from progressive abdominal distension, which was disclosed due to CSF overproduction by a choroid plexus papilloma. When the tumor was recognised by enhanced CT scan, her general condition was too poor to attempt a surgical procedure, and she died on March, 19, 1981. Histologically the neoplasm was a typical choroid plexus papilloma of the third ventricle. So far as we know, this case is the first one of the choroid plexus papilloma of the third ventricle in the neonatal period.
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