Objective To establish a ultrahigh-performance liquid chromatography-orbitrap high-resolution mass spectrometry(UHPLC-Orbitrap HRMS)method for the determination of the genotoxic impurity N-nitroso propranolol(NPPN)in propranolol hydrochloride sustained-release tablets.Methods The test sample was ultrasonically extracted using methanol as the solvent,then centrifuged and filtered before injection analysis.Chromatographic separation was performed using a 2.7 μm particle size C18 UHPLC column with a mobile phase of 0.1％formic acid(A)in water and 0.1％formic acid(B)in acetonitrile,using gradient elution.Mass spectrometry was conducted with an HESI ion source in positive ion parallel reaction monitoring(PRM)scan mode,monitoring the NPPN fragment ion at m/z 72.080 8,and quantification was performed using the standard curve method.Results The calibration curve was in good linearity in the range of 0.51-20.30 ng·mL-1 with excellent correlation coefficient(r)of 0.9999.The recoveries of NPPN at three levels(low,medium,and high)were in the range of 95.4％～98.3％,while the RSDs were from 2.5％to 4.2％.The limit of detection(LOD)was 0.20 ng·mL-1 while the limit of quantitfication(LOQ)was 0.51 ng·mL-1.This analytical method was used to determine NPPN in six batches of propranolol hydrochloride sustained release tablet samples.NPPN was detected in all six samples,among which the detection amount of 3 batches have exceeded the acceptable limit.Conclusion This method is sensitive,accurate,and fast,making it useful for pharmaceutical companies in controlling production processes and providing robust technical support for regulatory authorities.

Objective To establish a ultrahigh-performance liquid chromatography-orbitrap high-resolution mass spectrometry(UHPLC-Orbitrap HRMS)method for the determination of the genotoxic impurity N-nitroso propranolol(NPPN)in propranolol hydrochloride sustained-release tablets.Methods The test sample was ultrasonically extracted using methanol as the solvent,then centrifuged and filtered before injection analysis.Chromatographic separation was performed using a 2.7 μm particle size C18 UHPLC column with a mobile phase of 0.1％formic acid(A)in water and 0.1％formic acid(B)in acetonitrile,using gradient elution.Mass spectrometry was conducted with an HESI ion source in positive ion parallel reaction monitoring(PRM)scan mode,monitoring the NPPN fragment ion at m/z 72.080 8,and quantification was performed using the standard curve method.Results The calibration curve was in good linearity in the range of 0.51-20.30 ng·mL-1 with excellent correlation coefficient(r)of 0.9999.The recoveries of NPPN at three levels(low,medium,and high)were in the range of 95.4％～98.3％,while the RSDs were from 2.5％to 4.2％.The limit of detection(LOD)was 0.20 ng·mL-1 while the limit of quantitfication(LOQ)was 0.51 ng·mL-1.This analytical method was used to determine NPPN in six batches of propranolol hydrochloride sustained release tablet samples.NPPN was detected in all six samples,among which the detection amount of 3 batches have exceeded the acceptable limit.Conclusion This method is sensitive,accurate,and fast,making it useful for pharmaceutical companies in controlling production processes and providing robust technical support for regulatory authorities.

Objective To investigate the morphological changes in the upper airway after bimaxillary surgery in patients with skeletal Class Ⅲ malocclusion and the relationship between jaw movement and airway changes using CBCT.Methods This study involved 44 individuals(21 males and 23 females)receiving Class Ⅲ bimaxillary surgery.Preoperative and 3-6-month postoperative CBCT data were examined using Dophin3D 11.95 software.The alterations before and after upper airway surgery were analysed using paired t-test and non-parametric Wilcoxon rank sum test.The association between airway alterations and jaw movement was examined using Pearson's correlation coefficient.Results Patients who underwent Class Ⅲ bimaxillary surgery had significantly reduced upper airway volume,sagittal cross-sectional area,and minimum cross-sectional area(P＜0.01).A correlation exists between oropharyngeal volume change and point B change(P＜0.05).When B point recession was＞7 mm,the decrease in upper airway volume increased significantly(P＜0.01),as did the risk of minimum cross-sectional area of the patient's airway(P＜0.01).Conclusion ClassⅢbimaxillary surgery re-duces upper airway capacity.Postoperative reduction in upper airway capacity coincides with mandibular recession.Mandibular reces-sion(＞7 mm)may reduce postoperative upper airway capacity and increase the risk of OSAHS.Patients at risk of upper airway stenosis should have their protocol modified to reduce airway risk.

Temporomandibular joint (TMJ) diseases are common clinical conditions. The number of patients with TMJ diseases is large, and the etiology, epidemiology, disease spectrum, and treatment of the disease remain controversial and unknown. To understand and master the current situation of the occurrence, development and prevention of TMJ diseases, as well as to identify the patterns in etiology, incidence, drug sensitivity, and prognosis is crucial for alleviating patients′suffering.This will facilitate in-depth medical research, effective disease prevention measures, and the formulation of corresponding health policies. Cohort construction and research has an irreplaceable role in precise disease prevention and significant improvement in diagnosis and treatment levels. Large-scale cohort studies are needed to explore the relationship between potential risk factors and outcomes of TMJ diseases, and to observe disease prognoses through long-term follw-ups. The consensus aims to establish a standard conceptual frame work for a cohort study on patients with TMJ disease while providing ideas for cohort data standards to this condition. TMJ disease cohort data consists of both common data standards applicable to all specific disease cohorts as well as disease-specific data standards. Common data were available for each specific disease cohort. By integrating different cohort research resources, standard problems or study variables can be unified. Long-term follow-up can be performed using consistent definitions and criteria across different projects for better core data collection. It is hoped that this consensus will be facilitate the development cohort studies of TMJ diseases.