In order to examine the influence of X-ray irradiation on the demilune cells of the sublingual gland due to the existence of secretory granules, 10 Gy of X-ray irradiation was applied to the sublingual gland of mice at 3 hours after isoproterenol (IPR) administration. To inspect the influence of irradiation at 3 days after the irradiation, tissue images and results of autoradiography performed at 30 and 120 minutes (min) after ³H-leucine administration of the IPR administration (IPR/10Gy) group were compared with those of the non-IPR administration (nonIPR/10Gy) group. In transmission electron microscope images, swelling and pyknosis were observed in the rough endoplasmic reticulum of the nonIPR/10Gy group. The number of reduced silver grains per unit cell area in nonIPR/10Gy at 30 and 120 min after ³H-leucine administration was less and greater than that in the other 3 groups (nonIPR/0Gy, IPR/0Gy, and IPR/10Gy), respectively, from light microscope autoradiography images. At 120 min after ³H-leucine administration, the ratio of the number of reduced silver grains localized in the secretory granules to the total number of reduced silver grains in the demilune cells of the nonIPR/10Gy group was lower than that of the other 3 groups as indicated by electron microscope autoradiography images. Based on these results, it was apparent that the effect of irradiation was less on the demilune cells that discharged secretory granules than those that did not discharge them.

Approximately 40%–65% of new fitness club (FC) members cancel their membership within 6 months. To prevent such cancellations, it is essential to identify members at high risk of doing so. This study developed a model to predict the probability of discontinuing FC membership among new members. We conducted a cohort study and enrolled participants from 17 FCs in Japan. We asked 5,421 individuals who became members from March 29, 2015 to April 5, 2016 to participate in the study; 2,934 completed the baseline survey, which was conducted when the participants became FC members. We followed up the participants until September 30, 2016. We excluded 883 participants with missing values and 69 participants under aged 18 years; thus, our analysis covered 1,982 individuals. We conducted the random survival forest to develop the prediction model. The mean follow-up period was 296.3 (standard deviation, 127.3) days; 488 participants (24.6%) cancelled their membership during the follow-up. The prediction model comprised 8 predictors: age; month of joining FC; years of education; being under medical follow-up; reasons for joining FC (health improvement, relaxation); and perceived benefits from exercise (maintaining good body weight, recognition of one’s ability by other). The discrimination and calibration were acceptable (C statistic: 0.692, continuous ranked probability score: 0.134). Our findings suggest that the prediction model could assess the valid probability for early FC cancellation among new members; however, a validation study will be needed.