Objective: To understand the characteristics of sexual partners and the influence of having multiple sexual partners on substance use among young male students man who have sex with men (MSM) in China, and to provide scientific basis for the prevention and control of HIV/AIDS among young MSM students. Methods: A mixed recruitment method of snowball sampling and respondent driven sampling was used to recruit young MSM students in Beijing and Tianjin, and a questionnaire survey was conducted among 220 participants from November to December 2019. Chi-square test and generalized linear model multi-factor Logistic regression were used to analyze the influencing factors of substance use before sexual behavior. Results: The average age of them was (22.39±2.57) years old, 84.5% of them were students, the average age of first sexual behavior was (18.83±2.45) years old, 44.1% of them had two or more sexual partners (including fixed sexual partners, temporary sexual partners and commercial sexual partners), 22.7% had more than one male fixed partner. After adjusting for age and education, having multiple sexual partners was risk factor for drinking alcohol before sex (aOR=2.97) or substance abuse (aOR=2.39). Having male temporary sexual partner was an risk factor in substance use before sexual behavior(OR=4.10). Conclusion The characteristics of sexual partners among young MSM students are complex, and the proportion of multiple sexual partners is high. Having fixed single sexual partner can reduce the risk of substance use before sexual behavior. AIDS prevention education for young MSM students should be further strengthened.

Thoracic ossification of ligament flavum (TOLF) is a pathological process of heterotopic bone formation from ligamentum flavum tissue, which is the most common cause of thoracic spinal stenosis and thoracic myelopathy. Imaging examination is the predominant measure for localization and qualitative diagnosis for TOLF. Various TOLF classification systems have been reported currently, based on its morphology, distribution, configuration of compressed spinal cord or its association with peripheral tissue structures. However, there has been no unified classification due to confusing clinical applications. Therefore, we conducted a review to summarize TOLF classification systems and to evaluate the reliability of these classification systems and the diagnostic accuracy of various imaging modalities. As demonstrated in literatures, the diagnostic accuracy of radiography and the reliability of related classification were low. CT-based Sato classification (lateral, extended, enlarged, fused, tuberous) and Kuh classification (unilateral, bilateral, bridging), MRI-based Kuh classification (round, beak) and Chen Zhongqiang classification (isolated, skipping, continuous), Muthukumar classification combined with dural ossification (Tram track sign, Comma sign) elaborated ossification characteristics from different angles and dimensions. These classification systems were clinically significant in pathogenesis implication, risk assessment, treatment guidance and prognosis judgement, which showed high diagnostic accuracy and reliability. Combining multi-dimension and multi-level parameters of CT and MRI will play an important role in the diagnosis, treatment and new classification research of TOLF.

Objective To compare the function recovery of multiple injuries combined with floating knee joint injury and simple knee joint injury,and to analyze the risk factors.Methods A retrospective case control study was conducted to analyze the clinical data of 41 patients with multiple injuries combined with Blake and McBryde Ⅱ A floating knee injury admitted to Xijing Hospital of Air Force Medical University from June 2011 to June 2017.There were 26 males and 15 females,aged 18-76 years,with an average of 34.5 years.There were 25 patients with simple knee joint injury and and 16 patients with multi-joint combined injury involving knee joint and ipsilateral hip joint or ankle joint injury.Surgical fixation was performed in different parts by external fixation,intramedullary nail and plate screw fixation.According to the Kalstr(o)m and Olerud functional evaluation criteria,the excellent and good rate of postoperative functional recovery was compared between the two groups.The surgical fixation methods of the two groups were compared.Logistic regression analysis was performed on the influencing factors of functional recovery.Results The patients were followed up for 1-7 years,with an average of 3 years.The excellent and good rate of overall functional recovery in the two groups was 68％,and the rate was 84％ in simple knee injury group and 44％ in multi-joint combined injury group (P ＜ 0.01).There was no significant difference in the ratio of intramedullary nail and plate screw fixation between the two groups (P ＞ 0.05),while the proportion of the external fixation in the multi-joint combined injury group [31％ (5/16)] was significantly higher than that in the simple knee joint injury group [16％ (4/25)] (P ＜ 0.05).Logistic regression analysis showed that the rate of external fixation was an independent factor affecting the postoperative function (OR =0.15,P ＜ 0.01).Conclusions The postoperative function in multi-joint injury patients is poorer than in the single joint injury patients.The higher rate of using external fixation in multi-joint injury patients is a risk factor.For Blake and McBryde Ⅱ A floating knee injury combined with multi-joint injury,less external fixation should be used,so as to improve the postoperative function.

Objective: To identify the characteristics of social network and the association between ego-centric network and HIV status among young MSM Chinese students. Methods: The cross-sectional study was conducted in Chongqing, Tianjin, Harbin and Xi an city from April to December 2017 and from March to May 2018. A mixed recruitment method of snowball sampling and RDS approach was used to recruit participants who reported information on social network and received HIV test. The Multiple Regression Analysis method was used to for the analysis of association between ego-centric social network and HIV status of men who have sex with men (MSM) among young students. Results: The sample included 547 participants who nominated 1 088 social partners in total with average age of 13 to 60 years old. The MSM with different sexual orientation from their social members (aOR=0.38), embedded in a large network (aOR=0.63), with a high individual betweenness centrality (aOR=0.27) were at lower risk of HIV-positive status; while MSM who differed greatly in education level with their social members(aOR=1.60), existed in sexual networks(aOR=1.41), existed in the “risky networks” (aOR=1.88) , with high network density (aOR=1.91) and a high individual degree (aOR=4.10) had higher risk of HIV-positive status(P<0.05). Conclusion MSM with great difference in education level from social members, existed in sexual networks, with a large network density and a high degree were exposed to higher risk of HIV-positive status.

Ossification of posterior longitudinal ligament (OPLL) and ossification of ligamentum flavum (OLF) are clinically common heterotopic ossification diseases, which are the main causes of cervical and thoracic spinal stenosis and spinal cord injury. In some cases, OPLL and OLF may involve multiple spinal sites, individually or concurrently, increasing the difficulty of clinical diagnosis and treatment. This review initially attempts to define this specific ossification phenomenon as Tandem ossification of intraspinal ligaments (TOIL). It refers to a kind of severe spinal ligament ossification diseases caused by multiple factors, that OPLL and OLF occur alone or in combination at two or more sites of the cervical, thoracic, or lumbar spine with five or more ossified segments, progressively compressing the spinal cord or nerves, thereby resulting in a series of complex clinical symptoms. The prevalence of TOIL remains unknown, but its clinical detection rate is relatively high, and the most common TOIL is cervical OPLL combined with thoracic OPLL or/and OLF. Moreover, occurrence and development of TOIL involve many factors and its definitepathogenesis is not clear. Damage of upper and lower motor neurons can occur simultaneously in TOIL patients so that their clinical symptoms and signs often interfere with each other. TOIL has various forms, complex imaging features, and no uniform diagnostic and localization diagnostic criteria, which may easily lead to missed diagnosis and misdiagnosis. It is recommended that TOIL is identified by the typical symptoms and signs as the basis, CT three-dimensional reconstruction and MRI signs as the reference, and combination of the possible risk factors and clinical experience. Currently, surgical decompression for responsible lesions is the only effective treatment for symptomatic TOIL. However, domestic and foreign scholars still have great arguments on the optimal surgical strategy of TOIL. No consensus has been reached on how to determine the operating segment and the extent of decompression, which surgical approach and technique to be adopted, and when to select staged or one-stage combined surgery. Therefore, this review summarizes and discusses the current status and progress of the clinical characteristics and surgical strategies of TOIL through searching the relevant literature, to provide a reference for clinicians to diagnose and treat TOIL.

Objective:To evaluate the immunogenicity, safety, and immune persistence of the sequential booster with the recombinant protein-based COVID-19 vaccine (CHO cell) in healthy people aged 18-84 years.Methods:An open-label, multi-center trial was conducted in October 2021. The eligible healthy individuals, aged 18-84 years who had completed primary immunization with the inactivated COVID-19 vaccine 3 to 9 months before, were recruited from Shangyu district of Shaoxing and Kaihua county of Quzhou, Zhejiang province. All participants were divided into three groups based on the differences in prime-boost intervals: Group A (3-4 months), Group B (5-6 months) and Group C (7-9 months), with 320 persons per group. All participants received the recombinant COVID-19 vaccine (CHO cell). Blood samples were collected before the vaccination and after receiving the booster at 14 days, 30 days, and 180 days for analysis of GMTs, antibody positivity rates, and seroconversion rates. All adverse events were collected within one month and serious adverse events were collected within six months. The incidences of adverse reactions were analyzed after the booster.Results:The age of 960 participants was (52.3±11.5) years old, and 47.4% were males (455). The GMTs of Groups B and C were 65.26 (54.51-78.12) and 60.97 (50.61-73.45) at 14 days after the booster, both higher than Group A′s 44.79 (36.94-54.30) ( P value<0.05). The GMTs of Groups B and C were 23.95 (20.18-28.42) and 27.98 (23.45-33.39) at 30 days after the booster, both higher than Group A′s 15.71 (13.24-18.63) ( P value <0.05). At 14 days after the booster, the antibody positivity rates in Groups A, B, and C were 91.69% (276/301), 94.38% (302/320), and 93.95% (295/314), respectively. The seroconversion rates in the three groups were 90.37% (272/301), 93.75% (300/320), and 93.31% (293/314), respectively. There was no significant difference among these rates in the three groups (all P values >0.05). At 30 days after the booster, antibody positivity rates in Groups A, B, and C were 79.60% (238/299), 87.74% (279/318), and 90.48% (285/315), respectively. The seroconversion rates in the three groups were 76.92% (230/299), 85.85% (273/318), and 88.25% (278/315), respectively. There was a significant difference among these rates in the three groups (all P values <0.001). During the sequential booster immunization, the incidence of adverse events in 960 participants was 15.31% (147/960), with rates of about 14.38% (46/320), 17.50% (56/320), and 14.06% (45/320) in Groups A, B, and C, respectively. The incidence of adverse reactions was 8.02% (77/960), with rates of about 7.50% (24/320), 6.88% (22/320), and 9.69% (31/320) in Groups A, B, and C, respectively. No serious adverse events related to the booster were reported. Conclusion:Healthy individuals aged 18-84 years, who had completed primary immunization with the inactivated COVID-19 vaccine 3 to 9 months before, have good immunogenicity and safety profiles following the sequential booster with the recombinant COVID-19 vaccine (CHO cell).

Adjacent segment disease(ASD) refers to the degeneration of adjacent segments after lumbar fusion surgery, including intervertebral disc herniation, stress vertebral fractures, slippage, segmental scoliosis, spinal canal stenosis, and facet joint degeneration, which can lead to corresponding clinical symptoms such as lumbosacral pain, root lower limb pain, or intermittent claudication. The treatment of different pathological types of ASD varies. The patients with mild symptoms require conservative treatment and patients with severe symptoms require surgical treatment. In the past, open fusion surgery with posterior approach or intervertebral foramen approach was commonly used for surgical treatment, which had definite therapeutic effects. However, there were drawbacks such as large surgical trauma, excessive intraoperative blood loss, and slow postoperative recovery. With the booming development of minimally invasive spinal surgery technology in recent years, spinal surgeons actively use minimally invasive surgery for the treatment of ASD. It has advantages such as less bleeding, short hospital stay, fast recovery, and fewer complications (such as deep vein thrombosis and pulmonary embolism), but its indications are limited. Therefore, this article provides a reference for the choice of ASD treatment by reviewing the treatment modalities of ASD with different pathological types.

Objective:To analyze the prevalence and distribution characteristics of diffuse idiopathic skeletal hyperostosis (DISH) in hospitalized patients with thoracic ossification of the ligamentum flavum (TOLF).Methods:The clinical records of 132 consecutive TOLF patients from January 2018 to June 2019 were retrospectively studied. DISH was identified by the preoperative X-ray and CT and its prevalence was calculated. The prevalence of patients with different genders, different age groups and different ossification types was compared. The segmental distribution of DISH and the distribution in the upper (T 1-T 4), middle (T 5-T 8), and lower thoracic spine (T 9-T 12) were analyzed. Ossification degree of DISH was evaluated based on the Meta scoring system. The demographic characteristics (age, gender, BMI, etc.) were compared between DISH and non-DISH group. Results:Forty-nine patients was diagnosed as DISH with the prevalence of 37.1% in all included cases. The prevalence was about twice as high in male (46.3%) than in female (23.1%) ( χ2=8.806, P=0.003). The prevalence in the age groups of <40, 40-49, 50-59, 60-69 and ≥70 years was 20.0%, 28.0%, 34.4%, 44.0%, and 66.7%, respectively. The prevalence in long-segment TOLF patients (45.1%) was significantly higher than that in short-segment TOLF patients (24.0%) ( χ2=5.937, P=0.015). DISH most frequently affected T 8,9 levels (91.8%). The total number and mean number of ossified segments were 365 and 7.4, respectively. Ossification lesions in the upper, middle, lower thoracic spine accounted for 26.03%, 40.54%, and 33.15%, respectively. Grade I, grade II, and grade III ossification accounted for 21.4%, 28.5% and 50.1%, respectively. The mean age of the DISH group was older than the non-DISH group ( t=2.024, P=0.045). The proportion of male patients in the DISH group was significantly higher than that in the non-DISH group ( χ2=8.806, P=0.003). The average height and weight in the DISH group were significantly greater than those in the non-DISH group ( t=2.564, P=0.012; t=2.191, P=0.030), whereas no significant differences in BMI and constituent ratio of concurrent diabetes, cardiac disease, hypertension between two groups were observed. Conclusion:The prevalence of DISH in patients with TOLF is 37.1%. Male, elderly and long-segment TOLF patients are associated with higher prevalence. DISH frequently occurs in the middle and lower thoracic spine, and T 8,9 is the common affected segment. Ossification lesions may develop with age. Demographic characteristics of DISH group differ, to some extent, from those of non-DISH group.

Objective:To compare the safety and efficacy of the " step-up approach" versus the " step-jump approach" in treatment of infected pancreatic necrosis (IPN).Method:The clinical data of IPN patients who underwent step-up strategy or step-jump strategy treatment at the Department of Pancreatic and Biliary Surgery of the First Affiliated Hospital of Harbin Medical University from December 2018 to November 2022 were analyzed retrospectively. Propensity score matching (PSM) was done based on the nearest neighbor matching method (1: 1 ratio). After matching the baseline data (the caliper value was 0.01), a total of 62 patients with IPN were included, including 41 males and 21 females, aged (41.1±13.1) years old. Patients who were treated with the step-up strategy were included in the step-up group, while patients who were treated with the step-jump strategy were included in the step-jump group. There were 31 patients in each group after PSM, and the treatment effect of the two groups were compared.Results:Of the 62 patients with IPN, 43 received surgical intervention, and 19 were managed successfully using symptomatic anti-inflammatory treatment or percutaneous catheter drainage. The total hospitalization cost of patients in the step-jump group was significantly higher than that in the step-up group [122 000 (73 000, 179 000) yuan vs. 88 000 (46 000, 144 000) yuan, P=0.034]. The overall cure rate of IPN patients in the step-jump group was 93.5%(29/31). The 2 patients who died had type Ⅲ IPN. In the IPN patients in the step-up group were all cured, and the overall cure rate was 100%(31/31), with no death. There were no statistical differences between the two groups in the rates of death, postoperative complications, residual infection, debridement ≥2 times, and positive bacterial culture in blood or drainage fluid (all P>0.05). A total of 19.4% (12/62) patients had postoperative complications, including 4 patients with abdominal bleeding, 3 patients with new organ dysfunction, 2 patients with gastrointestinal bleeding, 2 patients with gastrointestinal fistula, and 1 patient with venous thrombosis in both lower limbs. Conclusion:Both the step-up treatment strategy and the step-jump treatment strategy were safe and effective for treatment of IPN patients.

Hemophilic arthritis(HA),caused by recurrent bleeding,can seriously affect patient quality of life and consumes extensive social and medical resources.There is thus a need to establish an animal model of HA for research;however,this is limited by ethical requirements.Here we review the recent literature and summarize research progress into animal models of HA at home and abroad,from the aspects of species selection,modeling method,histopathology,and imaging evaluation method.Species selection includes rodents such as mice,New Zealand rabbits,beagles,miniature pigs,and crab-eating macaques.Modeling method comprise gene knockout trauma models,gene knockout spontaneous models,and injection models.Among these,the gene knockout spontaneous model closely mimics the pathological process of spontaneous bleeding and concurrent arthritis in human HA,making it more relevant to human HA.However,due to high modeling costs,phenotypic instability,and low survival rates,this model is not the preferred choice for animal experimental studies.In contrast,gene knockout trauma models exhibit characteristics such as short modeling time,strong stability,and high success rates,thus being widely utilized in animal experimental research.Evaluation of HA models involves various imaging method including MRI,micro-CT,MSKUS/PD,in addition to various gross scoring method.By reviewing the progress of HA model research,more experimental evidence is provided for investigating the pathogenesis and validating the efficacy of HA treatments,thereby compensating for the lack of clinical data,particularly in the field of traditional Chinese medicine therapy.