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Biomedical subjects

S Takeno

Publications and source records attributed to S Takeno.

At least 73 records · Page 4Linked to original sources
PubMed1992

Experimental evidence of selective axonal regeneration in allogenic and isogenic Y-chambers.

Studies on axonal regeneration in Y-chambers over the past decade have consistently provided evidence of preferential growth toward a distal nerve piece. However, these findings are in contrast to the observations by Weiss and Taylor (1944. J. Exp. Zool. 95: 233-257), indicating that in fresh aortic Y-chambers regenerating axons had no tendency to grow into a channel containing a distal nerve piece as compared to an open channel. The discrepancy between Weiss and Taylor's findings and those of later authors remains unexplained. In the present study we repeated the investigations by Weiss and Taylor, using both isogenic and allogenic aortic Y-chambers. In control groups the aorta graft was frozen and treated chemically to kill all cells and to deactivate possible growth factors of protein nature. In these groups preferential growth toward the distal nerve was pronounced although such specificity in growth was evident also in the nontreated types of aortic chambers. The findings do not support the results presented by Weiss and Taylor.

Animals↗
PubMed1991

Involvement of the intestinal microflora in nitrazepam-induced teratogenicity in rats and its relationship to nitroreduction.

A study was undertaken to investigate the relationship between nitroreduction of nitrazepam and its teratogenic effects and the involvement of the intestinal microflora in Sprague-Dawley rats. Incubation of bacterial suspensions from rat cecal contents with nitrazepam resulted in extensive reduction to 7-aminonitrazepam. Rat liver homogenates also reduced nitrazepam but only under anaerobic conditions. Following oral administration of 300 mg/kg nitrazepam to pregnant rats, total excretion of reduced metabolites (7-aminonitrazepam and 7-acetylaminonitrazepam) in urine and feces accounted for approximately 30% of the administered dose. When antibiotics were administered to dams to deplete their intestinal microflora prior to administration to nitrazepam, the total excretion of the reduced metabolites in the urine and feces decreased to 2% of the dose. Nitroreductase activity of cecal contents was almost completely suppressed by antibiotic pretreatment, but the activity of liver homogenates was not significantly altered by the same treatment. The incidence of nitrazepam-induced malformations was markedly decreased by antibiotic pretreatment. These results suggest that the intestinal microflora plays an important role in the reductive metabolism of nitrazepam and that the teratogenicity of nitrazepam may be related to its nitroreduction by the microflora.

Animals↗
PubMed1991

Transantral ligation of the maxillary artery for refractory epistaxis. A case report.

A case of severe arterial epistaxis treated by transantral ligation of the maxillary artery is reported. A 66-year-old woman had recurrent left sided epistaxis from the posterior nasal cavity which was difficult to control by conventional nasal packing methods. Selective angiography was performed to identify the arterial flow patterns and site of bleeding which was confirmed to be the descending palatine artery. Following radiographical examination, ligation and clipping of the maxillary artery and its branches was performed with transantral approach under general anesthesia. No further epistaxis occurred after the ligation. This surgical procedure seems to be relatively simple and highly effective in the management of refractory epistaxis.

Aged↗
PubMed1990

Evaluation of drugs for treatment of urinary bladder dysfunction in conscious rats with intact pelvic nerve and after resection of the left pelvic nerve.

We studied the effects of drugs used for treatment of bladder dysfunction in conscious rats with intact pelvic nerves and also in rats at one or two weeks after nerve decentralization on the left side. Bladder contraction accompanying micturition was continuously induced by infusion of solution at a constant rate. When the effects of oxybutynin (3 mg/kg, i.p.) and terodiline (3 and 10 mg/kg, i.p.) on the cystometrogram were studied for about 2 hr, these drugs shortened and then prolonged the micturition interval (MI), but atropine (1 and 5 mg/kg, i.p.), butylscopolamine (20 mg/kg, i.p.) and nifedipine (3 mg/kg, i.p.) exhibited only a shortening effect on the MI. After injection of oxybutynin (10 mg/kg, i.p.), solution dribbled from the urethra for about 30 min. Terodiline (3 mg/kg) caused ischuria in the rats one week after resection of the left pelvic nerve, but not in the rats two weeks after surgery. Physostigmine (0.3 mg/kg, i.p.) improved micturition in the rats one week after surgery, but the effect was not evident in the rats with intact pelvic nerves. It was found that the drugs used for treating failure to store or expel urine exhibited a beneficial effect on micturition in rats with intact pelvic nerves and also in rats one week after nerve decentralization, respectively.

Animals↗
PubMed1990

[Tissue culture of middle ear epithelium of the guinea pig--differences of the cellular growth activity in the middle ear cavity using collagen gel culture method].

Primary tissue culture system from the middle ear and the tracheal epithelium of the guinea pig was established using collagen gel method. The cultured epithelium was studied by phase-contrast microscopy, light and scanning electron microscopy. The outgrowth area of the epithelium was quantitatively measured for period of up to ten days. In the middle ear cavity, the mucosal explants were sampled from various sites in order to compare their differential and proliferative activities. The mucosal explants attached on collagen substrates were composed of ciliated, non-ciliated, goblet and basal cells. This basic structure was similar to the natural middle ear epithelium. The ciliated cells showed well organized cilia. Most of the outgrowth cells devoid of fibroblastic cells in the monolayer were polygonal shaped with numerous microvilli. The morphology of the outgrowth cells changed from columnar or cuboidal to squamous shapes in the area away from the explants. There was a correlation between the distribution of the ciliated cells in the outgrowths and these in the explants. The explants with columnar or cuboidal ciliated epithelia sampled from the opening of the eustachian tube or its neighborhood formed more than eightfold outgrowth sheets in vitro. This is comparable to tracheal epithelia. On the other hand, the explants with simple squamous epithelia sampled from the area distal to the eustachian tube showed about fourfold proliferative activity. We concluded that this culture system would be useful for the study of cellular multiplication and differentiation mechanisms of the respiratory tract epithelium.

Animals↗
PubMed1990

[Cell culture of middle-ear epithelium of the guinea pig--histochemical localization of mitochondrial enzymatic activities in cultured cells].

Primary cell culture system from middle-ear epithelium of the guinea pig was established in defined condition. Mucosal cells were dispersed with enzymatic procedure and over 90% of the cell viability was obtained. Collagen gel and fibronectin coated Thermanox plate were used as culture substrates, and cultured cells on both materials formed confluent epithelial linings. Histochemical localization of succinate dehydrogenase, cytochrome oxidase and adenosine triphosphatase in mitochondria were examined. Cultured ciliated cells and some non-ciliated cells with numerous microvilli showed strong activities of succinate dehydrogenase and cytochrome oxidase. Also in vivo, normal ciliated epithelium near the eustachian tube in the middle-ear cavity of the guinea pig revealed strong mitochondrial metabolic activities. We concluded that this system would be useful for the study of cellular multiplication and differentiation systems of the middle-ear epithelium.

Adenosine Triphosphatases↗
PubMed1990

Teratogenic effects of nitrazepam in rats.

The teratogenicity of nitrazepam, a benzodiazepine-type drug, was investigated in Sprague-Dawley rats. Nitrazepam was administered to pregnant females at levels of 100, 200 or 300 mg/kg in a single dose on one of gestation days 10-14. Fetuses were examined for external and skeletal malformations on day 20 of gestation. Nitrazepam was found to produce various types of malformations, i.e., exencephaly, cleft palate, micrognathia, short or kinky tail and limb reduction defects. The predominant malformation was limb reduction defects, which were produced at high frequency by treatment on day 12 or 13 of gestation. Microscopic examination of limb buds revealed hemorrhage and mesenchymal cell necrosis at 24 hours after nitrazepam treatment.

Animals↗
PubMed1987

Strain differences in susceptibility to the embryotoxic effects of aminopyrine in mice.

Embryotoxic effects induced by aminopyrine were studied in two inbred strains of mice, C57BL/6N and DBA/2N. Aminopyrine was given by subcutaneous injection at a dose of 200 mg/kg on day 7, 8 and 9 of gestation. In both strains, aminopyrine-induced malformations such as omphalocele, club foot and kinky tail were observed, but the incidence of malformations was significantly higher in C57BL/6N than in DBA/2N. Maternal plasma levels of aminopyrine and its metabolites were significantly higher in C57BL/6N, compared to DBA/2N. Further, reciprocal crosses between these two strains were used to clarify whether the maternal or fetal genotype is more important in aminopyrine-induced embryotoxicity. F1 hybrid embryos developing in C57BL/6N or DBA/2N mothers were as resistant as inbred DBA/2N. These results suggest that strain differences in susceptibility to aminopyrine may depend on fetal genotype rather than maternal factors.

Aminopyrine↗
PubMed1986

In vivo and in vitro studies on fetal toxicity of benzodiazepines in rats.

In this study, we investigated whether the intensity in the embryotoxicity of benzodiazepines was related to maternal and fetal blood levels and also to their high binding to the fetoplacental structures in rats. Maternal and fetal levels of nitrazepam (NTZ) and nimetazepam were higher than the diazepam level after oral administration of these drugs (100 mg/kg). In vitro, the affinity of the drugs for the fetus corresponded to the drug levels in the maternal serum and fetus. In the embryo culture, NTZ had no direct teratogenicity but had embryocidal activity. On the contrary, the in vivo maternal serum treated with NTZ possessed both activities. From the above facts, and since there was no change in the in vivo embryotoxicity as a result of phenobarbital, it was suggested that the embryocidal activity of NTZ may be due to changes of maternal function depended upon the maternal serum.

Animals↗
PubMed1984

Fetal toxicity of benzodiazepines in rats.

This study was undertaken to evaluate fetal toxicity of benzodiazepine derivatives, nitrazepam, oxazepam, nimetazepam, clonazepam, diazepam and chlordiazepoxide. In fetotoxicities induced by the oral administration of these six drugs (100 mg/kg), nitrazepam (NTZ) and nimetazepam caused a great damage to the fetus compared with other analogues. The fetotoxicity of NTZ was dose-dependent at a dose of 50 to 100 mg/kg p.o. and its peak toxicity was observed in the group treated from the 8th to 10th day of gestation. Maternal serum and whole fetus concentration of NTZ were higher than that of diazepam which showed weak toxicity. It was suggested that the intensity of fetotoxicity induced by benzodiazepines was related to the amount of drug in blood of dam.

Abnormalities, Drug-Induced↗
PubMed1983

Alleviation of acetylsalicylic acid-induced fetal toxicity by calcium.

Alleviation of aspirin-induced fetotoxicity by calcium was investigated in rats. ASA (500 mg/kg s.c.) decreased the plasma Ca level in pregnant rats and that in the feto-placenta units. 0.05 M CaCl2 given to dams as tap water on days 8 through 20 of gestation inhibited ASA-induced hypocalcemic effect in maternal plasma. Tap water of 0.002-0.05 M CaCl2, Ca(OH)2 and Ca-lactate on days 8 through 20 of gestation alleviated malformations elicited by the administration of ASA (500 mg/kg s.c.) on the 11th day of gestation resulting in a decrease in the fetotoxicity in rats.

Abnormalities, Drug-Induced↗
PubMed1982

Fetal toxicity and hypocalcemia induced by acetylsalicylic acid analogues.

In the present study, we investigated a correlation of fetotoxicity induced by salicylic acid (SA) analogues to their hypocalcemic effect. Among of SA analogues, acetylsalicylic acid, salicylaldehyde, salicyl-alcohol, methyl salicylate and SA evoked a hypocalcemia in rats and mice but the other analogues had no effect by their single administration. The additional administration of dihydroxybenzoic acids elicited the hypocalcemia following the fetal toxicities induced by SA analogues paralleled to that of their hypocalcemic effect. A hypocalcemic effect was induced only by the benzoic acids with hydroxy group existing in ortho-position.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

Expression of proliferating cell nuclear antigen in cultured middle ear epithelial cells of the guinea pig.

Primary cultures of middle ear epithelium from the guinea pig were successfully established on type I collagen coated dishes. To characterize cellular outgrowth, antibodies to the proliferating cell nuclear antigen were used as a marker for spreading cells in the S phase of the cell cycle. A number of migrating epithelial cells positively stained for proliferating cell nuclear antigen after 7 and 14 days in culture. Confocal laser scanning microscopy was used to evaluate the localization pattern of this antigen, and the fluorescence intensity was quantified in different areas of the migrating epithelial sheet after various times in culture. Two distinct areas proved to be major sites of proliferating cell nuclear antigen expression. One was at the edge of the tissue explants from which multilayered epithelial cells had begun to migrate. The other was along the margin of the outgrowth, where the cells often had elongated shapes and were aligned in rows. The cells in both areas were identified as nonciliated cells; ciliated cells in the outgrowth showed little staining. We hypothesized that the outgrowth cells in this experiment might be identical to the migrating cells usually observed in renewing epithelia after injury. This model may provide a simple and reproducible method of evaluating the regenerative ability of the middle ear epithelium.

Journal Article↗
PubMedDate not supplied

Effects of gastrin on the histamine-secretory and proliferative activity of cultured carcinoid cells derived from the stomach of the rodent Mastomys natalensis.

The effects of gastrin on the synthesis and release of histamine and on cellular proliferation were investigated in a homotransplantable carcinoid tumor implanted in the rodent Mastomys natalensis and in cultured cells derived from the tumor. The homotransplanted tumor was immunopositive for histamine, synaptophysin and protein gene product 9.5, and its cells contained numerous secretory granules that were visualized by electron microscopy. When carcinoid cells were cultured in a medium with a high concentration of gastrin-I (10(4) pg/mL) for 7 days, large electron-dense secretory granules were characteristically observed in the cytoplasm. By contrast, only a few such granules and numerous secondary lysosomes were seen in cells that had been cultured in the same medium without gastrin-I. A high concentration of gastrin-I (10(4) pg/mL) significantly increased the release of histamine into the culture medium from the carcinoid cells compared with the control (P < 0.05). Cellular proliferation, as determined by monitoring the incorporation of [methyl-3H]-thymidine into the carcinoid cells increased significantly at lower concentrations of gastrin-I (10(2) and 10(3) pg/mL), (P < 0.05). At higher concentrations (10(4) pg/mL or more), gastrin-I had no effect on proliferation. These findings indicate that gastrin stimulates the synthesis and release of histamine by carcinoid cells, as well as their proliferation.

Animals↗
PubMedDate not supplied

Degeneration of spiral ganglion cells in the chinchilla after inner hair cell loss induced by carboplatin.

The anticancer drug carboplatin has been used to generate inner hair cell (IHC) lesions in the cochlea of chinchillas. This has provided a valuable model for the study of the relative roles of IHCs and outer hair cells (OHCs). In the present study, we examined the pathological and temporal relationships between the degeneration of the cochlear IHCs and type I spiral ganglion cells (SGCs). A single intravenous dose of 200 mg/m2 carboplatin produced extensive IHC loss with no apparent effect on the OHCs. The auditory brainstem response threshold was significantly elevated by 2 weeks following treatment and remained stable through 12 weeks. Elevated thresholds were well correlated with morphological lesions. On the other hand, the SGC population progressively decreased from 2 to 12 weeks after treatment, to about half of the control density values. A positive correlation existed between the density of SGC and the number of surviving IHCs. These results indicate that selective damage to IHCs causes a distinct loss of SGCs.

Animals↗