Objective: To prepare a composite membrane by chitosan/β-sodium glycerophosphate(CS/β-GP) thermosensitive hydrogel combined with stromal cell derived factor-1(SDF-1) and observe its biological characteristics in vitro. Methods: Different doses of SDF-1 were added into CS/β-GP solution and then the thermosensitive gel time was measured. The SDF-1/CS/β-GP solution was membrane paved and dried to prepare composite membranes. The morphological characteristics were observed by scanning electron microscope(SEM). Composite membranes were placed into cell culture medium, and the supernatant(n=3) was extracted after standing at 6, 12, 24, 36, 48, 60 h, respectively. The concentration of SDF-1 in the solution was measured. Bone mesenchymal stem cells(BMSCs) were cultured in the Transwell room, and the composite membranes containing different concentrations of SDF-1 were placed in the lower chamber. There were four groups(n=3): Group M0 used CS/β-GP membrane(control group), Group M1, M2, M3 used SDF-1/CS/β-GP membrane(SDF-1 was 100, 200, 400 ng/mL respectively). After culture for 6, 12 and 24 h, the cells under the membrane were preserved and Giemsa stained and counted. The absorbance(OD) value was measured by MTT method to calculate the cell proliferation rate. SPSS 19.0 was used for multi-factor analysis of variance. Results : After adding a certain amount of SDF-1 into CS/β-GP solution, the gel time did not change significantly(P>0.05). The SDF-1/CS/β-GP membrane was translucent and porous at 37 ℃. In this experiment, the volumic mass of SDF-1 released by SDF-1/CS/β-GP composite membrane increased gradually with the experimental time(P<0.01). Transwell cell chemotaxis test showed that the number of BMSCs cells with directional migration increased with the prolongation of observation time(P<0.01) and the increase of SDF-1 volumic mass(P<0.01). In MTT test, the OD value of migration cell solution increased with the prolongation of time(P<0.01) and the increase of SDF-1 volumic mass(P<0.01). Conclusion The SDF-1/CS/β-GP composite membrane has a porous structure and biological activity of chemotactic BMSCs directional migration. It is a potential membrane for guided tissue regeneration.

Objective To investigate the external radiation doses and occupational health examination data of radiation workers in medical institutions in Zhangjiagang City, China, explore the effects of long-term exposure to low-dose ionizing radiation on their health, and provide a reference for occupational health monitoring. Methods The radiation workers of medical institutions in Zhangjiagang City were selected as the research subjects. Their personal radiation doses and occupational health examination data were collected. A scale was used for mental health survey. The data were analyzed according to different clinical characteristic groups. Results During the 5-year period from 2019 to 2023, the average annual radiation dose received by radiation workers in medical institutions in Zhangjiagang City was 0.21 mSv/year. There were significant differences in the average annual radiation dose across these years and radiation workers with different occupations. The results of occupational health examinations showed significant difference in the total abnormal detection rate among these years (P < 0.01). There were significant differences in the abnormal rates of blood pressure, blood routine, and electrocardiogram across these years (P < 0.05). There were significant differences in the abnormal rate of routine blood test in radiation workers with different sexes, years of service, and radiation occupations (P < 0.01). There were significant differences in the abnormal rate of blood pressure in radiation workers with different sexes, ages, and years of service (P < 0.01). The mental health survey showed significant differences between the radiation and the non-radiation groups in terms of occupational stress, anxiety score, and depression score (P < 0.05). Conclusion Long-term low-dose ionizing radiation may have adverse effects on the physical and mental health of radiation workers, and it is necessary to strengthen the occupational health examination and radiation protection of radiation workers.