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Biomedical subjects

Y Imamura

Publications and source records attributed to Y Imamura.

At least 379 records · Page 21Linked to original sources
PubMed1986

Plasma levels and urinary excretion of batroxobin and its defibrinogenating effects in various animal species.

The plasma levels and urinary excretion of batroxobin administered to 6 species of animals were examined by an enzyme immunoassay method. Defibrinogenating effect of batroxobin was also studied in those species. The plasma levels of immunoreactive batroxobin disappeared exponentially in all the animals and differences in half-life were observed to occur according to species. The elimination half-life of immunoreactive batroxobin in the plasma was the largest in dogs, followed by rats, monkeys, guinea pigs, mice and rabbits. The extent of the defibrinogenating effect was also noted to vary according to the species, being greatest in dogs and then monkeys, mice, rats, guinea pigs and rabbits. Following the continuous infusion of batroxobin into dogs, its level in the plasma remained high over a considerable period of time and the defibrinogenating effect lasted in corresponding to its plasma level. The urinary excretion of immunoreactive batroxobin was quite small in these species, being 0.2-1.9% of the original dose.

Animals↗
PubMed1986

Metabolic fate of 125I-labeled batroxobin in rats and dogs.

125I-Labeled batroxobin was prepared and following its intravenous and subcutaneous administrations to rats and dogs, the blood radioactivity was determined. In the both species following the intravenous injections, the decrease in radioactivity was biexponential. Following subcutaneous administration, radioactivity became maximal at 6h and decreased in a manner similar to that of the beta-phase of the intravenous injection. The blood concentration of fibrinogen in dogs was also determined. After the intravenous injection, fibrinogen became undetectable 1h later, and appeared again in the blood at 24h. After the subcutaneous injection, the decrease was not so rapid. Fibrinogen resumed its original levels at 7 day after the administration in both the routes. Radioactivity after the both injections was excreted generally in the urine in about the same amounts. The total urinary and fecal excretions in rats and dogs were 80 and 95%, respectively. The distribution of radioactivity in the tissues was examined by counting technique and whole-body autoradiography. Radioactivity predominantly accumulated in the thyroid and stomach and could also be found in the kidneys and liver in fair amounts. The distribution patterns of radioactivity for both the routes of administrations and also for male and pregnant rats were basically the same. In fetus rats, a slight distribution was noted. From the results of gel filtration chromatography and trichloroacetic acid fractionation, [125I] batroxobin was metabolized soon after the administration to afford low molecular substances such as 125I-ion in the plasma and urine.

Animals↗
PubMed1986

Immunochemical characterization of anti-islet cell surface monoclonal antibody from nonobese diabetic mice.

We have produced a monoclonal antibody 3A4 to the surface of islet cells by fusing spleen lymphocytes from nonobese diabetic (NOD) mice. To identify the molecular weight of specific target antigens reacting with 3A4, 125I-surface-labeled In-111 insulinoma cells were solubilized and extracts were absorbed with 3A4, and immunoprecipitates were followed by polyacrylamide gel electrophoresis and autoradiography. 3A4 recognized two major polypeptides with apparent molecular weights of radioactive 64K and inactive 28K. In order to evaluate the antibody-mediated cytotoxic mechanisms of 3A4, complement-dependent antibody-mediated cytotoxicity (C'-AMC) and antibody-dependent cellular cytotoxicity (ADCC) were tested using a method of specific 51Cr release. In the study for C'-AMC, even over wide ranges of concentration of antibody and rabbit complement, purified 3A4 had no apparent cytotoxic effects on In-111 cells. On the other hand, significant ADCC was observed at an antibody concentration of 10 micrograms/ml and a target:effector cell ratio of 1:40 (P less than 0.01). Finally, the effects of 3A4 on glucose-stimulated insulin release were examined in isolated rat islets. At a glucose concentration of 16.7 mM, 3A4 significantly inhibited the insulin release either in the presence or absence of complement (P less than 0.01). In conclusion, 3A4 could not only bind but also be active to the target cells. Therefore, this monoclonal antibody should be a useful tool to permit a detailed analysis of the pathogenesis of type I diabetes mellitus.

Animals↗
PubMed1986

The localization of human keratin proteins at cytological and histological levels in carcinomatous and sarcomatous lesions.

Immunoperoxidase staining for human keratin proteins was performed cytologically on samples from 90 patients with malignant tumors, and histologically on samples from 164 patients with malignant tumors. At the cytological level, almost all tumor cells not only in squamous cell carcinoma but also in nonsquamous cell carcinoma were positive for keratin proteins, in contrast with the apparent abscence of keratin proteins in sarcoma. At the histological level, almost all neoplastic cells of squamous cell carcinoma were positive for keratin proteins, the same as at the cytological level. In contrast, among cases of nonsquamous cell carcinoma, the frequency of appearance of keratin proteins varied according to the organ; it tended to be low in tumors with relatively good prognosis, such as carcinomas in the digestive system or thyroid cancer, and to be high in tumor with poor prognosis, such as pulmonary cancer, gallbladder cancer and endometrial cancer. However, there was a marked difference between the frequency of appearance of keratin proteins at the cytological level and that at the histological level, particularly in the cases of gastric cancer.

Antibodies↗
PubMed1986

[Study of chemotherapy in the field of internal medicine--clinical experience with SF-SP].

UNLABELLED: An SF-SP Tegafur spansule preparation was administered to 26 patients with advanced cancer (24 evaluable), and the clinical effectiveness and toxicity were studied. In most of cases, daily dosages of 800 mg were administered in two parts, in a few cases, daily dosages of 1,000 mg or 1,200 mg were given. Clinical effectiveness: The evaluation of effectiveness was based on the Koyama-Saito group criteria. Of the 24 evaluable cases, PR was observed in 3 cases of gastric cancer, one of colon cancer, and one of liver cancer, a total of 5 cases (20.8%). In these 5 cases the daily dosage was 800 mg, and the median duration of PR was 51 days. TOXICITY: TOXICITY was observed in 3 (11.5%) of the 26 cases.

Administration, Oral↗
PubMed1986

Messenger RNA coding for argininosuccinate synthetase in citrullinemia.

Messenger RNA coding for argininosuccinate synthetase (ASS), extracted from the livers of some patients with citrullinemia, was analyzed using a cell-free translation system and dot and Northern blot hybridization with cDNA probe for ASS. In patients with quantitative-type citrullinemia, called type II here, previous studies have demonstrated that the hepatic content of the enzyme was about 10% of the control value, whereas the translatable mRNA level for the enzyme was similar to that of control livers. Here, we confirmed that the type II liver contained an almost normal amount of mRNA coding for ASS, judged by the dot-blot hybridization technique with cDNA. Northern blot hybridization of RNA indicated that there was hybridizable mRNA of approximately normal size (about 1.7 kilobase [kb]) in each, suggesting that large structural gene deletions had not occurred. These results indicate that in type II citrullinemia, the decrease in the enzyme protein is due either to increased degradation of the enzyme or to decreased or inhibited translation in the liver. Another type of citrullinemia was found and classified as type III. It is characterized by no detectable enzyme activity for ASS or translation activity for ASS mRNA. However, a smaller amount of RNA molecule hybridized for ASS cDNA was detected.

Adult↗
PubMed1986

[Comparative studies on the pharmacokinetics between THP and adriamycin in the same patients].

The pharmacokinetic properties of THP and ADM were comparatively studied in the same patients with various cancers. The concentration of ADM in either plasma or blood cells was higher than that of THP from 5 minutes to 24 hours after administration. The metabolites of ADM such as aglycones were detected in plasma until 3 hours after administration, but these were never detected in blood cells. By contrast, the metabolites of THP were detected until 24 hours after administration. These results suggested that THP was metabolized in tissues and excreted into urine and that the rate of metabolism and excretion of THP was faster than that of ADM. Distribution volumes (V1, V2, and V3) of THP were larger than those of ADM. The above results strongly suggested that THP would be easily transferred into the tissues, but that in the case of slower transferring tissues with lower K13 values, ADM rather than THP would be easily transferred to the tissues. These pharmacokinetic properties suggested that the toxicity of THP might be diminished compared with that of ADM.

Aged↗
PubMed1985

[Evidence for the internalization and degradation of insulin in cultured Bri-7K human lymphocytes].

We have studied the internalization of insulin and the mechanism of insulin degradation in cultured Bri-7K human lymphocytes. The internalization of 125I-insulin was observed by using an acid extraction technique by Heigler's method which removed surface-bound insulin, leaving only intracellular insulin associated with cells. Insulin binding to Bri-7K cells reached a peak at 15 min and showed a gradual fall thereafter at 37 degrees C. Internalization of insulin rose with a peak in 30 min, and its rate was nearly 25% of the total specific cell-associated radioactivity. Insulin degrading activities in Bri-7K cells were examined as to precipitability with trichloroacetic acid (TCA method), Sephadex G-50 column chromatography (gel chromatography method) and the ability to bind to specific receptors on Bri-7K cells (rebinding method). Under conditions demonstrating that the insulin degradation didn't take place in the medium but was cell-mediated, the insulin degradation was not demonstrated by the TCA method. Chromatographic studies showed that the extractable radioactivity consisted almost entirely of intact insulin, whereas the supernatant and the nonextractable radioactivities consisted of large molecular weight material and intact insulin. Thus, the apparent degradation of insulin was not detectable by the TCA and gel chromatography methods, however, using the rebinding method, we could obtain results demonstrating that fair amounts of insulin in the supernatant were degraded. These results suggest that the products of insulin degradation are peptides with a molecular size similar to insulin itself but with little or no receptor binding activity. In conclusion, insulin internalizes into Bri-7K cells at physiological temperature, and the mechanism of insulin degradation in Bri-7K cells seems to be a limiting proteolysis of insulin by specific enzyme(s).

Cell Membrane↗