Objective:To understand the social networking using status of medical students, develop the social networking using status scale (SNUSS) and evaluate its reliability and validity.Methods:In March 2018, 665 valid questionnaires were collected via cluster sampling. The scale was retest in 46 subjects after an interval of 2 months. Factor analysis, correlation analysis and t-test were used to calculate the structure validity and content validity of the scale to evaluate the scale validity, and internal consistency reliability, broken half reliability and retest reliability were used to evaluate the scale reliability. Results:The result of exploratory factor analysis showed NSUSS had two subscales: the dimension of maintaining existing social relations and social network use and the dimension of expanding circle of friends and social network use. The result of confirmatory factor analysis showed that the factor load value of each item was greater than 0.500 ( P < 0.05), and the model fitted well ( χ2/ df = 2.873, GFI = 0.970, CFI = 0.971, RMSEA = 0.074). The r value of correlation between SNUSS and MSPSS was 0.295. I-CVIs were all equal to 0.90, and S-CVI was 0.90, the internal consistency reliability was 0.764, the split-half reliability was 0.555, and the retest reliability was 0.526. Conclusion:SNUSS has good reliability and validity for the use of social network among medical college students, and the use of social network is related to perceived social support.

Objective : To explore the effect on children's occlusion and temporomandibular joint (TMJ) after placement of preformed metal crowns and provide a reference for the restoration of defective primary molars. Methods : A total of 39 children who underwent all primary molar metal crown restorations under general anesthesia were enrolled. The participants underwent occlusal contact area, percentage of total occlusal force, asymmetric ratio of occlusal force and occlusal contact time examinations with the T-scan computerized occlusal analysis system. Vertical dimension of occlusion (VDO) was measured using a dental vertical dimension gauge. TMJ dysfunction signs were recorded using the modified clinical dysfunction index (Di), and TMJ dysfunction symptoms were recorded using questionnaires. All data were collected at pretreatment, 1-week, 1-month, 3-month, and 6-month follow-up visits. Results: The occlusal contact area at the 3-month and 6-month follow-up visits returned to the occlusal contact area of pretreatment, and the difference was statistically significant (P>0.05). Compared with pretreatment, the percentage of total occlusal force at the 3-month and 6-month follow-up visits increased significantly, and the difference was statistically significant (P<0.05). The asymmetric ratio of occlusal force and the occlusal contact time were significantly decreased at the 6-month follow-up visit (P<0.05). The vertical dimension of occlusion recovered after one month of treatment (P>0.05). The final statistical analysis of the TMJ assessment showed that there was no significant difference in the clinical disorder index and TMJ dysfunction symptoms before and after treatment (P>0.05). Conclusions After undergoing all primary molar metal crown restorations, occlusal re-equilibrations were attained after approximately one month. The percentage of total occlusal force and occlusal stability were significantly increased after six months of treatment, without significant temporomandibular joint dysfunction.

Objective:To investigate drug resistance gene in Mycoplasma pneumoniae(MP) and the distribution of 13 respiratory pathogens in bronchoalveolar lavage fluid(BALF) of children with Mycoplasma pneumoniae pneumonia(MPP).Methods:A total of 100 BALF of children with MPP in Peking University Third Hospital and Peking University First Hospital from January 2018 to January 2019 were collected.Fluorogenic quantitative PCR was used to detect nucleic acid and it′s drug resistance gene of MP and multiple PCR method was adopted to detect influenza A virus, influenza A virus-H 1N 1, influenza A virus-H 3N 2, influenza B, human parainfluenza virus, adenovirus, human bocavirus, human rhinovirus, Chlamydia pneumoniae, human metapneumovirus, MP, human coronavirus, and respi-ratory syncytial virus gene, and the results were compared by using Chi square test. Results:In 100 BALF samples, MP and drug resistance gene were detected by fluorogenic quantitative PCR.Totally, 83 cases (83.00%) were MP positive and 78 cases (93.98%) were drug resistant.All of them had the point mutations A2063G in V region of 23S rRNA domain.A total of 13 kinds of respiratory pathogens were detected by multiplex PCR method, and 89 cases (89.00%) were positive.Totally, 79 cases (79.00%) were MP positive, of which 74 cases (74.00%) detected only MP, and 5 cases (5.00%) detected MP combined with other pathogens.Other pathogens were detected in 10 cases (10.00%). The virus detection rate of 0-4 years old group was higher than that of >4-6 years old group ( P=0.042) and >6 years old group ( P=0.002), and the differences were statistically significant. Conclusions:MP can be detected in most BALF samples of MPP children, the drug resistance phenomenon is serious, and the main point mutation is A2063G.There were other respiratory pathogens and 2 or 3 pathogens were detected in a small number of BALF samples.

Objective:To understand the research progress and quality of lung cancer screening guidelines and consensus in China and abroad, and to provide reference for the formulation of high-quality lung cancer screening guidelines in China.Methods:Databases including PubMed, Medline, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure, SinoMed, VIP and Wanfang Data were searched, websites and important references were also searched by hand retrieval. The Appraisal of Guidelines for Research & Evaluation Ⅱ(AGREE Ⅱ) and Reporting Items for Practice Guidelines in Healthcare (RIGHT) were used to assess the quality of newly published or updated guidelines and consensus.Results:A total of 9 guidelines and consensus published between 2015 and 2020 were included in this study, with countries including the United States, China, Canada, Saudi Arabia and South Africa. The field of scope and purpose and clarity of presentation scored relatively high but the rigor of development and applicability scored low. Five guidelines were judged to be A-level, all of which were published abroad, and the remaining four were B-level, including three guidelines and consensus issued by China and 1 guideline issued by South Africa. The report rate of RIGHT were higher in basic information and background, lower in review and quality assurance, funding and declaration and management of interests. There were 5 guidelines with a good level and 4 guidelines and consensus with a moderate level. The best overall quality guidelines were those published by the American College of Chest Physicians in 2018 and by the Canadian Task Force on Preventive Health Care in 2016.Conclusions:The number of countries and institutions that issue lung cancer screening guidelines and consensus had been increasing gradually, but the quality in China remained low. It is necessary to develop high-quality lung cancer screening guidelines suitable for China's national conditions in combination with evidence-based methods to guide practice.

Objective:To investigate the clinical therapy of one-stage internal and external fixation combined with early perforator fiap for treatment of ankle fracture dislocation with soft tissue defects of Gustilo types Ⅲ.Methods:A retrospective study was conducted of the 20 patients with ankle fracture dislocation of Gustilo type Ⅲ who had been treated from May 2014 to July 2017 at Deparment of Traumatic Orthopaedics, the Second Hospital of Tangshan. There were 14 males and 6 famales among the patients, aged from 18 to 58 years (average, 40 years). There were 5 cases of Gustilo type ⅢA, 12 cases of type ⅢB, and 3 cases of type ⅢC; AO classification of ankle fractures: 4 cases of type A, 7 cases of type B, and 9 cases of type C; The wound size ranged from 4 cm×3 cm to 20 cm×9 cm. All patients were treated by primary internal and external fixation plus secondary transfer with a perforator flap. The times from injury to initial surgery ranged from 1 to 8 h (average, 5.5 h), the period from injury to secondary flap transfer ranged from 7 to 21days (average, 12 days). Among them, 11 cases of posterior tibial artery perforator flap, 5 cases of fibular artery perforator flap, 1 case of anterior ankle flap, and 3 cases of posterior tibial artery perforator flap combined with fibular artery perforator flap.Results:All 20 cases of limb preservation were successful, and there were no amputees. 9 patients showed superficial infection, no deep infection and osteomyelitis occurred. All 19 cases of flap survived, 1 case of distal part of posterior tibial artery perforator flap was necrosis, and the skin graft was cured later. All patients were followed up for 6 to 18 months (average, 12 months). The flap healed well. There was no sinus tract and bone exposure. The sensory recovery was S1 in 2 fiaps, S2 in 12 flaps, S3 in 6 flaps. The fracture healing time vanged from 4 to 10 months (average, 6.5 months), no bone disunion in patients. According to the American foot ankle surgery scoring system, the efficacy was assessed: 4 excellent cases, 11 good cases, 3 fair cases, 2 poor cases, yielding an excellent to good rate of 75%.Conclusions:One-stage internal and external fixation combined with early perforator fiap transfer is an effective strategy for treatment of ankle fracture dislocation with soft tissue defects of Gustilo types Ⅲ, due to its advantages of shortened treatment period, possibility for early rehabilitation, decreased complications and satisfactory functional recovery.

Objective:To analyze the differences in clinical characteristics, microbiologic distributions, in vitro susceptibility, treatment and outcomes between elderly and young/middle-aged patients with nocardiosis.Methods:A total of 27 patients diagnosed with nocardiosis by bacteria culture and gene sequencing in our hospital from May 2007 to September 2011 were included.Patients were separated into two groups according to their ages.Clinical characteristics, laboratory tests, treatment and prognosis were compared between the two groups.Results:Of the 27 patients, 11 were male and 16 were female, with a median age of 50 years(range, 20-84 years old)and a median course of 3.0 months(range, 0.5-60.0 months). There were 6 cases in the elderly group and 21 cases in the non-elderly group.The common underlying diseases were chronic pulmonary disease(4/6, 66.7%), metabolic disease(2/6, 33.3%)and connective tissue disease(2/6, 33.3%)in the elderly group, and connective tissue disease(9/21, 42.9%), chronic pulmonary disease(6/21, 28.6%)and hematological disease(2/21, 9.5%)in the non-elderly group.Results of laboratory tests revealed that white blood cell counts were normal or elevated, lymphocyte percentages decreased and neutrophils percentages were elevated in both two groups.All patients in the elderly group had pulmonary infection, while 71.4%(15/21)had pulmonary infection and 28.6%(6/21)had disseminated infection in the non-elderly group.The proportion of patients with pulmonary consolidation on CT was higher in the elderly patients than in the non-elderly patients(100% vs.42.9%, P=0.02). The detection rates of N. cyriacigeorgica, N. farcinica, N. abscessus, N. Africana and N. wallacei were 50.0%(3/6), 16.7%(1/6), 16.7%(1/6), 16.7%(1/6)and 0%(0/6)in the elderly group and 23.8%(5/21), 42.9%(9/21), 42.9%(9/21), 4.8%(1/21)and 14.3%(3/21)in the non-elderly group, respectively.The mortality rate was 16.7% in the elderly patients and 28.6% in the non-elderly patients.The 5-year survival rates in both two groups were 100%. Conclusions:Elderly patients with nocardiosis often have underlying pulmonary disease with a long disease course. N. farcinica is the main observed strain.Multiple nodules and plaques and consolidation are common on CT.Multi-drug combinations are recommended in treatment.Concomitant fungal or other bacterial infections are factors for poor prognosis.The long-term prognosis is good in patients with nocardiosis.

In recent years,the application of machine learning in the field of radiotherapy has been gradually increased along with the development of big data and artificial intelligence technology.Through the training of previous plans,machine learning can predict the results of plan quality and dose verification.It can also predict the multi-leaf collimator (MLC) positioning error and linear accelerator performance.In addition,machine learning can be applied in the quality assurance of intensity-modulated radiotherapy to improve the quality and efficiency of treatment plan and implementation,increase the benefits to the patients and reduce the risk.However,there are many problems,such as difficulty in the selection,extraction and calculation of characteristic value,requirement for large training sample size and insufficient prediction accuracy,which impede its clinical translation and application.In this article,research progress on the application of machine learning in the quality assurance of IMRT was reviewed.

Machine learning has developed rapidly in recent years.Using machine learning to predict the radiotherapy outcomes and complications can more accurately evaluate the patients' conditions and take appropriate treatment measures as soon as possible.The non-dose and dose related factors generated during radiotherapy are filtered and input into the algorithm model,then corresponding prediction result can be obtained.There are many algorithm models to predict survival rate,tumor control rate and radiotherapy complications,and the predicted result are more accurate now.However,the algorithm model also has various problems,and it needs constant exploration and improvement.

Background Giant idiopathic macular hole (IMH) severely affects visual acuity and increases operative difficulty during the surgery,so modifying or optimizing the operation method is helpful for improving the prognosis.Objective This study aimed to evaluate the efficacy and safty of vitrectomy combined with free internal limiting membrane transplantation for large IMH.Methods A prospective serial cases-observational study was carried out under the informed consent of each patient.Forty-two eyes of consecutive 42 patients with IMH of mean diameter (814.31±112.95)μm were included in the Second Hospital of Hebei Medical University from January 2013 to November 2015.All the eyes received vitrectomy combined with free internal limiting membrane transplantation and 12％ C3F8 filling.The best corrected visual acuity (BCVA) (LogMAR),inner segment/outer segment (IS/OS) defect range,external limiting membrane defect range,retinal thickness at macular fovea were measured with slit lamp microscope,indirect ophthalmoscope and spectral-domain optical coherence tomography (SD-OCT) before surgery and 1,3,6 and 12 months after surgery.Results IMH complete closure in 97.6％ eyes (41/44) at 12 months after surgery.BCVA was improved after operation and showed a significant difference among various time points (F =28.032,P＜0.001).The IS/OS defect range was (1 112.00±45.44),(859.00±84.55),(649.00±52.47),(486.00±46.88) and (320.00±45.13) μm before surgery and 1,3,6 and 12 months after surgery,showing a significant difference among different time points (F=38.761,P＜0.001),and the IS/OS defect range was gradually shrinked after operation compared with that before operation (all at P＜0.05).The mean defect range of external limiting membrane was (1 038.00 ±39.63),(748.00±64.12),(585.00±48.88),(438.00±42.84) and (265.00±28.97)μm before surgery and 1,3,6 and 12 months after surgery,with a significant difference among various time points (F=36.459,P＜0.001),and the mean defect range of external limiting membrane was evidently reduced (all at P＜0.05).The foveal retinal thickness value was increased at 3,6 and 12 months after surgery,which was significantly higher than that 1 month after surgery (all at P＜0.05).The high reflect signal was faded away at 3 months after operation,indicating that implanted internal limiting membrane was decomposed and metabolized.Conclusions Vitrectomy combined with autologous internal limiting membrane transplantation seems to be safe and effective for large IMH.

Objective To establish serum NGAL reference range of healthy populations in Xi'an Area.Methods 2 665 cases (aged 6 to 95 years old,male 1 370,female 1 295) of health-check people were collected from March 2014 to October 2016 in Medical Examination Center of Shaanxi Provincial People's Hospital,and 682 cases (aged 0 to 6 years old,male 356,female 326) were collected from preschool children of prevention.Serum NGAL concentration of them were analysed by immunoturbidimetry method with the Automatic Biochemical Analysis Assembly Line of Beckman-AU5800,and the detection data for statistical analysis.Then established the reference range of serum NGAL population of different age and different sex in Xi'an.Results The serum NGAL levels in healthy subjects showed a skewed distribution,which were preschool children under 6 years of age 37.66±23.12 ng/ml,6～15 years 39.25±25.34 ng/ml,16～49 years 46.68±27.06 ng/ml,and 50～ 69 years 57.82±29.13 ng/ml.Compared the first two with the latter,there was a significant difference (t=0.589,P＜ 0.05).The serum NGAL levels of over 70 years were 61.87 ± 32.64 ng/ml,and there was a significant difference between the ages of 15 and 49 and over 70 years (t=8.529,P＜0.01).At the same time,the serum NGAL was closely correlated with age (r=0.298,P＜0.01).But there was no significant difference in serum NGAL level between male and female (t=0.263～0.542,all P＞0.05).87ng/ml was the upper limit of the reference value for the age of 50 years.Conclusion The level of serum NGAL was related to age and increased with age,but not with gender.