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Biomedical subjects

Y Hashimoto

Publications and source records attributed to Y Hashimoto.

At least 1,711 records · Page 95Linked to original sources
PubMed1975

Hypothalamic control of the pituitary-testicular relation in fetal rats: measurement of collective volume of Leydig cells.

On the 20th day of gestation in pregnant rats, the male fetuses were subjected to surgical hypophysectomy by decapitation or to intracranial paraffin injection which compressed the fetal brain. Autopsy was done on the 22nd day of gestation. The collective volume of Leydig cells in the left fetal testis was estimated by Chalkley's method. Decapitation of a fetus caused a significant retardation in increase of the collective volume of Leydig cells 2 days later. In fetuses given an intracranial paraffin injection, the Leydig cell volume was increased significantly compared with normal fetuses on the 20th day of gestation but was far smaller than that in their intact littermates. This effect of paraffin compression was completely prevented by injections of LRH. The Leydig cell volume remained extremely small in decapitated fetuses given LRH. The observations suggest that in the male rat the hypothalamus begins to govern a pituitary gonadotropic function before birth.

Animals↗
PubMed1975

Cell density dependence of the aggregation characteristics of the cellular slime mould Dictyostelium discoideum.

We have measured fruiting body density and spore formation efficiency in Dictyostelium discoideum as functions of initial cell density. Experiments were performed on agar made up with distilled water and on buffered agar. Minor differences are seen; these are discussed. The functions show 4 regions of density dependence which can be accounted for by changes in aggregation characteristics with density and changes in the efficiency of spore differentiation. The results are discussed in terms of the relaying mechanism for signal propagation controlling cell aggregation. They extend earlier measurements by Bonner & Dodd and by Hohl & Raper, supply data for a quantitative model of the aggregation process, allow estimates of signal range, and show the importance of entrainment between neighbouring centres in defining aggregation territories.

Cell Aggregation↗
PubMed1975

Neuromuscular blocking properties of some antibiotics in man.

Neuromuscular blocking properties of ribostamycin (1 gm), dibecacin (100 mg) and tobramycin (60 mg) were studied in a man during anesthesia and surgery by observing the effects of these antibiotics on muscle twitch tension. These drugs alone did not show any neuromuscular blocking action in those therapeutic doses. However, during the recovery phase of d-tubocurarine block the intravenous administration of 1 gm of ribostamycin caused a fairly rapid decrease in twitch tension. Tobramycin 60 mg did not show any remarkable effect, but dibecacin 100 mg produced a slight potentiating effect on the action of d-tubocurarine. The enhancement of the action of d-tubocurarine was antagonized promptly by edrophonium and more slowly by calcium.

Anti-Bacterial Agents↗
PubMed1975

Studies on the absorption, distribution and excretion of radioactivity after intravenous and intraperitoneal administration of 14C-methyl ester of amphotericin B.

Distribution and balance studies with carbon-14-labeled amphotericin B methyl ester (AME) were carried out in mice. The radioactive AME was administered by either the intraperitoneal (i.p.) or intravenous (i.v.) route. In the organ distribution study, the percent radioactivity accumulating in the lung of i.v. treated mice at 1 hour after administration was about 150 times greater than that observed when the intrapertinoneal route was used. No accumulation of radioactivity with time was detected in the kidneys of either the i.v. or i.p. treated mice. After 4 days, about 51% of the total radioactivity was excreted into the urine and feces of mice after i.v. administration, but only about 15% of the total radioactivity was excreted in the case of mice receiving radioactive AME by the i.p. route. In the identification of the substances excreted in the urine, thin-layer chromatography (TLC), radioactivity, and bioautographic evidence suggest that there was no detectable de-esterification of AME to the parent compound in mice treated either intraperitoneally or intravenously with AME.

Amphotericin B↗
PubMed1975

Radiosensitivities of DNA molecules in lymphocytes from the circulating blood of man.

The radiosensitivities of DNA molecules from lymphocytes of human circulating blood were examined by alkaline sucrose gradient centrifugation. The single-strand breaks of DNA per rad, including the breaks formed under the present alkaline condition, were 1.2 plus or minus 0.1 breaks per 10-12 daltons DNA per rad. When the cells were transformed, the number of breaks was found to increase to 1.8 plus or minus 0.2 breaks per 10-12 daltons DNA per rad. The lymphocytes are capable of rejoining radiation-induced single-strand breaks of DNA. The rate of rejoining was dependent upon types of the suspending medium. The rate increased to ten times of that of the non-transformed cells upon transformation.

Carbon Radioisotopes↗
PubMed1975

Cell kinetics of gastric carcinoma and other gastric lesions in rats by N-methyl-N'-nitro-N-nitrosoguanidine with or without Tween 60.

Male Wistar rats were divided into three groups for studying the chronic effect of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), in continuous dose of 50 mg/L in drinking water, or 50 mg/L MNNG and 0.4% Tween 60 in drinking water. From the 2nd to 50th week after the administration of MNNG, every 3 or 5 rats were sacrificed and autopsied after the intraperitoneal injection of 1 muCi 3-H-thymidine/g body weight at 2- or 3-week intervals. The resected stomachs were studied morphologically and autoradiographically. Six cases of experimental gastric cancer were produced that fulfilled Stewart's criteria. Autoradiographically, there was no significant different in the flash labeling index in the normal antral mucosa, in the non-pathologic antral mucosa, and in the cancerous lesion, but generation time and DNA synthesizing time of the cancerous lesion were 2 or 3 times longer than those of the glandular stomach of normal rats reported by Galjaard. They were also longer than those of the non-pathologic antral mucosa of rats treated with MNNG. These experiments results were discussed, comparing with cell kinetics of the gastrointestinal tracts in man.

Administration, Oral↗
PubMed1975

Damaged DNA in lymphocytes of aplastic anemia.

The size of single-stranded DNA in lymphocytes in GO stage from 22 patients with acquired primary and secondary aplastic anemia was estimated by alkaline sucrose gradient centrifugation. The average size was 9.3 (+/-0.3) times 10(7) daltons. The lymphocytes of patients contained significantly more single-strand breaks in DNA, compared to those of normal persons. The difference in size of single-stranded DNA which had been present in nontransformed lymphocytes could also be observed in transformed lymphocytes. Some characteristic differences could be observed in the sedimentation patterns of single-stranded DNA in the lymphocytes of patients with aplastic anemia and those of normal persons. The single-strand breaks in DNA suggested that the repair processes were disturbed in the DNA molecules of circulating lymphocytes from patients with acquired primary and secondary aplastic anemia.

Anemia, Aplastic↗
PubMed1975

A tumor-specific cytotoxic and neutralizing factor in rats immunized with ascites hepatoma induced by azo dyes.

Transplantation immunity of Donryu rats against ascites hepatoma AH-64A induced by azo dye was demonstrated by intraperitoneal injection of tumor cells pretreated with heteroantibodies in vitro. Hyper-immunity was induced by successive challenges with fresh tumor cells. The cytotoxic effect of the serum of resistant rats (RRS) against AH-64A tumor cells was not reduced after absorption with normal rat liver cells, but was slightly reduced after absorption with normal rat spleen cells. The cytotoxicity was absorbed completely with 5 times 10(6) AH-64A tumor cells. AH-64A, -B, -C, and -D are ascites hepatoma cell lines originating from a single Donryu rat. AH-64A and AH-64B cross-reacted with RRS while AH-64C and AH-64D, chemically induced DBLA-6 leukemia cells and normal lymph node cells of rats, did not react with RRS in indirect immunofluorescence and cytotoxicity tests. A neutralization test was carried out by treating 2 times 10(5) tumor cell with either RRS or immune spleen cell in vitro and then injecting them subcutaneously into irradiated rats (400 R). It was found that 1:20 dilution of RRS protected the rats against AH-64A tumor cell growth while 1:40 and 1:80 dilutions of RRS caused some protection. A subcutaneous tumor mass developed after transplantation of tumor cells treated with RRS, but after about 2 weeks this began to decrease in size and disappeared completely within 6 weeks after transplantation. Treatment of AH-64A tumor cells with immune spleen cells at cell-to-cell ratios of 1:200 and 1:100 caused complete neutralization while normal spleen cells at a ratio of 1:200 had slight effect. Treat;ent with immune spleen cells prevented tumor growth from t;e start. Most of the surviving animals were resistant to c,allenge with 1 times 10(5) fresh AH-64A cells. RRS was fractionated by cellulose acetate membrane electrophoresis and the amounts of beta1- and gamma-globulin fractions were found to be 48 and 42% more than in normal rat serum. The immunoelectrophoretic pattern of resistant rat serum showed a stronger IgM precipitin line than that of normal rat serum.

Animals↗
PubMed1975

Transplantation immunity of rats induced by hepatoma cells treated with heteroantibody.

Tumor cells from rat hepatomas, AH-414 and AH-64A induced by azo dye, were preincubated in vitro with different dilutions of rabbit anti-hepatoma serum. Then 10(6) cells were inoculated intraperitoneally into Donryu rats. After 6 weeks, rats surviving without tumors showed resistance to further challenge with the same tumor cells. The ratio of the number of surviving rats after challenge with 10(5) fresh tumor cells to those surviving after inoculation with serum-treated tumor cells was maximal using dilutions of antiserum of 1:240 with AH-414 tumor cells and of 1:400 with AH-64A cells. Pooled sera from AH-64A-resistant rats, 2 weeks after a 3rd challenge with 10(7) fresh tumor cells (RRS Lot III), had a cytotoxic effect on AH-64A cells at dilutions of up to 1:64 while sera isolated after the 1st or 2nd challenge (RRS Lot I or II) were weakly cytotoxic. The cytotoxicity was complement-dependent and stable on heating at 56 degrees for 30 min. RRS Lot III was active in the indirect immunofluorescence test. Rabbit anti-rat liver serum did not induce resistance to AH-64A in Donryu rats although the dilutions used had the same immune adherence or cytotoxic titer as rabbit anti-hepatoma serum. Rabbit anti-Donryu rat hepatoma serum failed to induce resistance to cells of a 3-methylcholanthrene-induced sarcoma, AMC 60, of ACI/N rats. The correlation between the immune adherence and cytotoxic titers of the rabbit antiserum and its effectiveness in sensitizing the animals against tumor cells is discussed.

Animals↗
PubMed1975

Carcinogenic effect of 1-butyl-1-nitrosourea on female Sprague-Dawley rats.

Carcinogenic effect of a single oral administration of 300 or 200 mg/kg body weight of 1-butyl-1-nitrosourea (BNU) and continuous oral administration of 400 ppm solution of BNU in the drinking water for 5, 10, 15, and 20 weeks to female SD rats was studied. In addition, the number of spleen cells capable of forming plaques (PFC) against primary immunization with sheep red blood cells was investigated in various stages of the animal experiments. With a single oral administration of BNU, tumors developed in 31/50 (62%) rats between the 25th and 75th week. They were most frequently seen in the mammary gland (40%), followed by the stomach (10%), kidneys (8%), and ovary (8%). Leukemia was found in 8%. No dose-effect relationship was observed in these 2 experimental groups. On the other hand, tumors developed in 67/77 (88%) of the rats that received BNU in their drinking water. The incidence of tumors was highest in leukemia (61%), followed by mammary tumors (26%), intestinal tumors (12%), and ear duct tumors (8%). There was a dose-effect relationship among the 4 groups in the latent period and target organs for tumor development. Although the PFC count of the rats receiving BNU for 5 weeks recovered gradually to about 50% of the control level at the end of the 25th experimental week, it remained less than 10% of the control level for the whole experimental period in those receiving BNU longer than 10 weeks. Therefore, it was apparent that the tumors developed, proliferated, and finally killed the host rats in highly immunosuppressive state.

Adenocarcinoma, Papillary↗