Objective:To prepare a monoclonal strain of mumps virus of genotype F，which is intended to be applied as a national standard strain，and to provide corresponding virus strain resources for the surveillance，prevention and control of mumps.Methods:The plaque purification technique was used to pick monoclonal strains on Vero/hSLAM cells. The biological characteristics and stability of the monoclonal virus strains were evaluated by observing the cytopathic effect of the monoclonal virus strains，morphological observation of virological characteristics，determination of virus titer and whole-genome sequencing，and mycoplasma detection.Results:After infection of Vero/hSLAM cells，the monoclonal strain of mumps virus constructed after plaque purification could cause cell fusion. Under the negative staining electron microscope，the virus particles were spherical，with a diameter between 100 and 200 nm，and had an obvious envelope. The virus titer of the 2 nd to 6 th generations was between 10 6 and 10 7 TCID 50/ml. Through whole-genome sequencing and phylogenetic analysis，the full length of the virus genome sequence was obtained as 15 384 bp，and it was confirmed that the monoclonal virus strain was of genotype F. The nucleotide difference rate between the 2 nd and 6 th generations was 0.013%. Conclusion:The monoclonal strain of mumps virus constructed in this experiment has typical cytopathic effects and typical morphological structures. The virus has good activity and stable genetic characteristics，and can be used as a candidate strain for application as a national standard strain. It can be used for reagent research and development，evaluation of immunization effects，and other subsequent work.

Objective:To prepare a monoclonal strain of mumps virus of genotype F，which is intended to be applied as a national standard strain，and to provide corresponding virus strain resources for the surveillance，prevention and control of mumps.Methods:The plaque purification technique was used to pick monoclonal strains on Vero/hSLAM cells. The biological characteristics and stability of the monoclonal virus strains were evaluated by observing the cytopathic effect of the monoclonal virus strains，morphological observation of virological characteristics，determination of virus titer and whole-genome sequencing，and mycoplasma detection.Results:After infection of Vero/hSLAM cells，the monoclonal strain of mumps virus constructed after plaque purification could cause cell fusion. Under the negative staining electron microscope，the virus particles were spherical，with a diameter between 100 and 200 nm，and had an obvious envelope. The virus titer of the 2 nd to 6 th generations was between 10 6 and 10 7 TCID 50/ml. Through whole-genome sequencing and phylogenetic analysis，the full length of the virus genome sequence was obtained as 15 384 bp，and it was confirmed that the monoclonal virus strain was of genotype F. The nucleotide difference rate between the 2 nd and 6 th generations was 0.013%. Conclusion:The monoclonal strain of mumps virus constructed in this experiment has typical cytopathic effects and typical morphological structures. The virus has good activity and stable genetic characteristics，and can be used as a candidate strain for application as a national standard strain. It can be used for reagent research and development，evaluation of immunization effects，and other subsequent work.

In order to analyze the clinical characteristics of death cases in the oral emergency depart-ment of the stomatological hospital,and to improve the first aid technique before and in hospitals,we col-lected the clinical data of death cases in the Department of Oral Emergency in Peking University School and Hospital of Stomatology from January 2010 to January 2023 for retrospective analysis.General cha-racteristics,such as the patients'gender,age,chief complaint,maxillofacial diseases,systemic under-lying diseases,rescue situation,cause of death and seasonal distribution of death were summarized.The results showed that a total of 8 death cases(5 males and 3 females)occurred during the 13-year period,ranging in age from 40 to 86 years,with a median age of 66 years.Among the 8 patients,5 reported bleeding from oral cancer,1 reported chest tightness and dyspnea after oral cancer surgery,1 reported loss of consciousness after maxillofacial trauma,and 1 reported oral erosion and aphagia.All the 8 pa-tients had one or more underlying diseases,such as hypertension,coronary heart disease,diabetes,renal failure,and cerebral infarction,etc.and 2 of them showed dyscrasia.Among them,the cause of death in 5 cases was respiratory and circulatory failure caused by oral cancer rupture and hemorrhage or poor sur-gical wound healing and hemorrhage;1 case was uremia and hyperkalemia leading to circulatory failure;1 case was asphyxia caused by swelling of oral floor tissue after maxillofacial trauma;and the other case was acute myocardial infarction caused circulatory failure after oral cancer surgery.According to the vital state at the time of treatment,6 patients had loss of consciousness,respiratory and cardiac arrest before hospital,and 2 patients suffered from loss of consciousness,respiratory and cardiac arrest during treat-ment.All the patients received cardiopulmonary resuscitation and some advanced life support measures,and the average rescue time was 46 min.Due to the low incidence of death in the oral emergency depart-ment,medical personel have little experience in first aid.First aid training and drills and assessment should be organized regularly.First aid facilities should be always available and regularly maintained by special personnel,such as electrocardiogram(ECG)monitor,defibrillator,simple breathing apparatus,oxygen supply system,negative pressure suction system,endotracheal intubation and tracheotomy equip-ment.The death cases mainly occurred in the elderly patients with oral cancer bleeding and systemic un-derlying diseases.Education of emergency awareness for the elderly patients with oral cancer after surgery should be enhanced.Medical staff should strengthen first aid awareness and skills.