[Airway parameters and reference value range of high-resolution CT reconstruction in general population].

Objective: To investigate the measurement of small airways by high-resolution CT and image post-processing software. Screen and analyze the reconstructed airway parameters in order to find the best imaging biomarker parameters of small airway changes and calculate the reference value range; meanwhile, explore its influencing factors. Methods: From a water plant and a medical school, 169 cases of the general population aged 20 to 60 were selected as research objects, and questionnaire surveys and CT tests were performed, and CT data were reconstructed with image post-processing software. The reference value range of the general population was evaluated, and a linear mixed effect model was used to adjust the age, gender, height, BMI, and smoking status, and analyze the influencing factors of airway parameters. Results: The ratio of sixth-grade tracheal wall area to total tracheal area in the Left B1+2 to carina was (53.01±13.35) %, Left B9 to carina was (50.44±12.98) %, Right B1 to carina was (52.73±12.22) %, and Right B9 to carina was (52.93±11.85) %. The ratio of nineth-grade tracheal wall area to total tracheal area in the Left B1+2 to carina was (44.08±14.66) %, Left B9 to carina was (42.44±15.89) %, Right B1 to carina was (46.51±14.03) %, and Right B9 to carina is (43.54±15.87) %. BMI affect the area of the tracheal wall, all p value<0.05. Conclusion: High-resolution CT small airway morphology can make a preliminary assessment of the susceptible population of small airway-related diseases based on a range of reference values, and prevent and control it in combination with influencing factors.

[Study on fibrosis changes in the lungs of mice caused by repeated inhalation of polyhexamethyleneguaidine disinfectant].

Objective: To explore the lung damage caused by repeated inhalation of polyhexamethyleneguanidine (PHMG) disinfectant aerosol and the corresponding toxicological characteristics. Methods: Thirty four-week-old mice of C57BL/6N strain were randomly divided into three groups, the control group, low-dose group, and high-dose group. Each group had 5 male mice and 5 female mice. Lab II-level purified water was used in the control group. The PHMG disinfectant aerosol was generated by using the ultrasonic atomization of the aqueous solution containing PHMG. The PHMG concentrations in the low-and high-dose groups were 0.1 mg/ml (0.01%) and 1 mg/ml (0.1%), respectively. The concentration of PHMG in the post-chemical exposure room was 1.03 mg/m(3) and 9.09 mg/m(3) according to the air sampler analysis. The experimental mice were exposed to the PHMG in dynamic respiratory exposure mode for 4 hours every day in 21 days. After 21-day exposure, bronchia alveolus lung fluids (BALFs) were used to evaluate the inflammatory cells in the lungs, and pathological evaluation, special staining and immunohistochemical methods were further performed to evaluate the key indicators of pulmonary fibrosis. Results: Compared to the control group, the body weight of mice in the high-dose group was significantly decreased (P<0.05), while that of mice in the low-dose group did not significantly differ (P>0.05). The number of inflammatory cells in BALFs of low-dose exposed mice was slightly reduced, and the lung tissue pathology began to show lung damage with early fibrosis symptoms (P<0.05). The pathological examination of mice in the high-dose group showed changes in pulmonary fibrosis. Immunohistochemical staining showed that pulmonary fibrosis marker, α-SMA, was significantly increased in low-dose group and high-dose group (P<0.05). Conclusion: The repeated inhalation of PHMG disinfectant could cause lung damage such as pulmonary fibrosis in mice. It could suggest that special warnings should be given to this common disinfectant and respiratory protection measures should be adopted during industrial production and daily use.