The effects of gast1in on the cell kinetics of the gastric mucosa were studied in the rats. The labelling index by tritiated thymidine of the cell in the mucous neck zone began to rise 14 hours after a single dose of tetragastrin at 100 or 1,000 µg/kg or synthetic human gastrin at 1,000 µg/kg and reached the peak at 18 hours. With tetragastrin 100 µg/kg administered subcutaneously together with a depot for 35 days, observations were made on the change in the turnover rate of the gastric epithelium by means of labelling index. The turnover rate was delayed in the surface epithelium and accelerated in the cells at the lower part of the foveolae in the gastrin-administered group. The cell suspension prepared from the rat gastric mucosa by trypsin digestion was cultivated with 5 per cent of CO2 in air for 48 hours. The group which was added with 10 µg/ml of tetragastrin showed fluctuations in the labelling index almost similar to the groups administered 100 and 1,000 µg/kg in vivo. It might be possible to support the hypothesis that gastrin not only has a trophic effect on the mucous neck zone but it also might be concerned with the turnover of the mature stage of gastric mucosa.
Changes of electrical cell-surface charge associated with cell cycle were examined electrophoretically in the synchronous culture of HeLa S3 cells. The electrophoretic mobility of the cells increased abruptly in the mitotic phase as high as 45% compared with that of cells in the S phase. This difference of mobility was obtained by comparing pure population of mitotic cells and S-phase cells. Mitotic cells were also found to be more susceptible to neuraminidase than S-phase cells in term of electrophoretic mobility, a greater amount of sialic acid being correspondingly released from the former. The mechanism of the electrokinetic change associated with the processes of cell cycle is discussed, with special reference to the distribution of electric charge in the cell surface membrane.
We elucidated the pattern of skin cleavage lines of the neck of Japanese cadavers and studied the scarring in 42 cases of radical neck dissection for the removal of metastatic nodules from the malignant tumors of the oral region, in the operation of which one incision was made parallel to, and another perpendicular to, the cleavage lines. From this study we came to the following conclusions: 1) The cleavage lines run parallel in ring-form around the neck, with the exception of the back and the lowermost part of the base of the neck. Seen from the side, the lines run horizontally across the neck. 2) Raised and widened scars were few at the site of the incision parallel to the cleavage lines but there were seen of ten at the site of the perpendicular incision. 3) There were no raised postoperative scars in the patients who had received radiotherapy prior to the time of observation.
In order to find a simple and effective method for endodontic treatment of recalcitrant cases, the efficacy of ammoniacal silver nitrate was re-evaluated. The modified serial tube dilution method was conducted to determine the effective antimicrobial concentration of ammoniacal silver nitrate on selected test microorganisms and clinical isolates. The effective antimicrobial concentration for the most resistant microorganism, Streptococcus faecalis, was 5.0×10-10 g/ml and the effectiveness persisted for several days. The diffusion ability of 4% ammoniacal silver nitrate into the dentinal tubules from root canal wall was also tested with freshly extracted teeth treated as in routine procedure for root canal therapy. The diffusibility was evident and the extent of infiltration was various, with more infiltration at cervical dentin than at apical one.
Six toothbrushing methods were evaluated using several kinds of toothbrushes. Two kinds of electric toothbrushes were tested also. Forty-two adults who had normal dentition and clinically healthy periodontal tissue, aged 20 to 34, 36 males and 6 females, voluntered for this study. The plaque score was calculated by the modified Volpe s method on which Suzuki et al. reported before. The scoring of the plaque was restricted to the six teeth (6/41|14/6). The average percentage of plaque removal from the total (labial and lingual) tooth surface by different toothbrushing methods was as follows: (1) 75.2± 9.9% by the Fones method with a hard brush, (2) 71.7 ± 11.1% by the Scrub method with a hard brush, (3) 67.4 ±12.5% by the modified Stillman’s method with a hard brush, (4) 64.7 ± 13.7% by the National electric toothbrush with a soft brush, (5) 62.9 ± 13.6% by the Roll method with a hard brush (6) 58.l ± 16.3% by the Charters method with a brush of a medium hardness, (7) 55.2 ± 10.2% by the Bass method with a brush of a medium hardness. A similar tendency was obtained independently on the labial, lingual and papillary tooth surface. The hard brush was the most effective for the plaque removal by all kinds of brushing methods.