Biomedical subjects
Publications and source records attributed to F Kato.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
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A new apparatus incorporating a unique type of swivel device was devised for chronic intravenous infusion in unrestrained rats. The swivel requires very little torque for rotation, ie, one-fourth that of the standard swivel, yet is 1/30 as expensive. A coil spring tube, located between the swivel and the catheter, allows the rat unhampered movement within the metabolic cage. Because the catheter follows the rats' movements freely, only two silk sutures are required to secure it to the animal. No statistically significant differences between experimental and control rats were observed in terms of body weight gain, food intake, nitrogen balance, or caloric efficiency. This apparatus should prove useful in many areas of research.
Testicular tumors of germ cell origin are extremely rare in rats. We encountered 2 cases of teratoma and embryonal carcinoma in the testes of 8- and 10-week-old Sprague-Dawley IGS rats. A unilateral tumor mass with bilateral testicular atrophy was observed macroscopically in both cases. Microscopic examination revealed that the tumor mass had characteristic features of a teratoma and was composed of several types of differentiated cells and tissues at various stages of maturation. Embryonal carcinoma tissue, composed of undifferentiated cells with an embryonic and anaplastic appearance, was observed within the tumor mass. In addition, foci of intratubular teratomas and embryonal carcinomas were observed in the testis on the side without any obvious mass. No obvious germ cells were observed in the seminiferous tubules in the remnant nontumorous area. Furthermore, intratubular transition of cells was observed from the embryonal carcinoma tissue to the squamous epithelium. This finding indicates that an embryonal carcinoma differentiates toward a teratoma even at a very early stage of development of the germ cell tumor.
Induction of a plasmid-integrative J7W-1-related phage in Bacillus thuringiensis serovar indiana by ethidium bromide was influenced by the temperature at which the host cells were cultured. Under optimal growth conditions, the maximum titer of the phage produced by the serovar indiana reached 1.2 x 10(6) PFU/ml at 37 degrees C while at 27 degrees C it was lower by an order of magnitude (1.3 x 10(5) PFU/ml). The temperature-sensitive period was estimated to occur early during the phage induction. However, the temperature effect observed with the serovar indiana did not occur with the serovar israelensis. In the latter case, the phage induction was the same at 37 degrees C or 27 degrees C. Thus we assume that the temperaturesensitive phage induction observed with the serovar indiana as host was not a phenomenon caused by the phage genome but rather by product(s) encoded by certain host gene(s).
Bacillus thuringiensis serovar israelensis, a bacterium which possesses plasmid transfer ability after mating, has been lysogenized by plasmid integrative phage J7W-1. The induction of phage in this J7W-1 lysogen was observed after mating with phage-insensitive strains, such as B. thuringiensis serovar thuringiensis, B. cereus and B. subtilis, as well as the phage-sensitive strain serovar israelensis. The phage induction was not observed after mating with B. thuringiensis strains AF101, serovar dendrolimus and serovar indiana. Because these strains are naturally associated with J7W-1 or its related phage, the data strongly suggest a constitutive expression of the repressor encoded by the prophage in these strains. However, the phage induction was observed in B. thuringiensis serovar aizawai, although it contained the J7W-1 DNA homologous region(s).
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