Dermatology and venerology is a clinical discipline characterized by morphology.With the development of the internet and the application of internet in education,the features and advantages of internet teaching are gradually recognized including high flexibility,rich information and good student-teacher interaction.This article focused on the establishment and practice of internet teaching to improve teaching quality.

Objective To analyze MRI features of real tears and pseudotears of posterior horn of the lateral meniscus (PHLM) at the insertion site of meniscofemoral ligament(MFL), and to discuss main points of differential diagnosis. Methods MR images of 32 patients with PHLM tears and 30 patients with anterior cruciate ligament tears but without PHLM tears confirmed by arthroscopy were analyzed retrospectively. Another 20 asymptomatic volunteers as controls underwent MR examination and analyzed. The number of consecutive slices displaying longitudinal increased signal in sagittal images and the length in axial images were evaluated. The one?way analysis of variance, χ2 test and ROC curve were used to analyze diagnostic value of different MRI findings. Results Longitudinal line with abnormal increased signal (pseudotear) was found in 82.0% (41/50) normal insertion site of MFLs. The typical MRI finding of real tears was peripheral longitudinal linear high signal in PHLM which reached the margin of articular surface. In sagittal images, longitudinal linear high signal was shown in (5.8 ± 1.2) slices in knees of real tears, which was more than (2.6±1.1) slices and (2.7±1.4) slices in pseudo?tear groups (F=60.9, P<0.01). The area under ROC curve was 0.96 for differentiating real tear from pseudo-tear using the number of consecutive slices displaying longitudinal increased signal in sagittal images. With a threshold of five or more consecutive images with abnormal longitudinal increased signal as the positive standard of continuous?line sign, the overall sensitivity, specificity and accuracy for diagnosing real tear were 90.6%(29/32), 90.2%(37/41) and 90.4%(66/73), respectively. The axial images showed that the length of increased signal line in the outer of PHLM was (16.4±4.9) mm in patients with real tears, which was longer than pseudo?tear groups with length of (8.1 ± 3.2) mm and (6.0 ± 3.1) mm (F=17.0, P<0.01). The area under ROC curve was 0.92 for differentiating real tear from pseudo?tear using the length in axial images. The zip sign was defined when its length was not less than 10 mm. The sensitivity, specificity and accuracy of the zip sign was 84.4%(27/32), 90.2%(37/41) and 87.7%(64/73) respectively. In coronal images, high signal of MFL attachment insertion was shown in 71.9%(23/32), 60.0%(15/25) and 10/16 cases, there was no significant difference (χ2=0.98, P=0.61). Conclusion The continuous?line sign and zip sign are characteristic findings of PHLM tears at the insertion site of MFL attachment, which are valuable for differential diagnosis with pseudotears at the insertion site of MFL.

Hepatitis B virus (HBV)-induced hepatocellular carcinoma (HCC) is one of the most frequently occurring cancers. Hepadnaviral DNA integrations are considered to be essential agents which can promote the process of the hepatocarcinogenesis. More and more researches were designed to find the relationship of the two. In this study, we investigated whether HBV DNA integration occurred at sites of DNA double-strand breaks (DSBs), one of the most detrimental DNA damage. An 18-bp I-SceI homing endonuclease recognition site was introduced into the DNA of HepG2 cell line by stable DNA transfection, then cells were incubated in patients' serum with high HBV DNA copies and at the same time, DSBs were induced by transient expression of I-SceI after transfection of an I-SceI expression vector. By using nest PCR, the viral DNA was detected at the sites of the break. It appeared that integration occurred between part of HBV x gene and the I-SceI induced breaks. The results suggested that DSBs, as the DNA damages, may serve as potential targets for hepadnaviral DNA insertion and the integrants would lead to widespread host genome changes necessarily. It provided a new site to investigate the integration.

Objective:The purpose of this paper is based on the concept of enhanced recovery after surgery, to discuss the timing of taking food and water in knee arthroplasty patients, as well as its feasibility and safety, so as to improve the quality of quality nursing services.Methods:The 226 knee arthroplasty patients in Luoyang Orthopedic-Traumatological Hospital (Henan Provincial Orthopedic Hospital) from September 2020 to November 2021 were selected and divided into a control group and a experimental group using the random number table method, with 113 cases in each group. The control group adopted a conventional postoperative feeding management method; the experimental group adopted the early and timely feeding management method after comprehensive assessment. The data were compared between the two groups, including the incidence and severity of postoperative nausea and vomiting within 6 h and from 6 to 24 h after surgery , the incidence of thirst and hunger at 2 h, 4 h and 6 h postoperatively, and the comfort level.Results:The incidence of postoperative nausea and vomiting was lower in the experimental group [19.5%(22/113), 13.3%(15/113)] than in the control group [32.7%(37/113), 23.9%(27/113)] within 6 h and from 6 to 24 h after surgery, and the severity (21 cases of gradeⅠ, 10 cases of gradeⅡand 6 cases of grade Ⅲ) was also lower than in the control group (17 cases of gradeⅠ, 29 cases of gradeⅡand 18 cases of grade Ⅲ), and the differences were all statistically significant ( χ2 = 5.16,4.21, Z = -2.72, P<0.05). The incidence of thirst were lower in the experimental group [14.2%(16/113), 8.0%(9/113), 2.7%(3/113)] than in the control group [26.5%(30/113), 29.2%(33/113), 40.0%(35/113) at 2 h, 4 h and 6 h postoperatively, and the incidence of hunger at 4 h and 6 h postoperatively [11.5%(13/113), 8.0%(9/113)] were lower than in the control group [32.7%(37/113), 34.5%(39/113)], with statistically significant differences ( χ2 values were 5.35 to 32.39, all P<0.05). The postoperative comfort scale scores of physiological (31.04 ± 1.00) and psychological (33.50 ± 1.45) were higher in the experimental group than in the control group (27.46 ± 1.78) and (31.37 ± 1.29), and the differences were statistically significant ( t values were -102.36 to -66.26, all P<0.05). Conclusions:Early postoperative feeding management at the right time reduces the incidence and severity of postoperative nausea and vomiting inknee arthroplasty patients. In addition, it can also reduce the incidence of thirst and hunger, and improve patients′ postoperative physiological and psychological comfort, which has a facilitating effect on achieving rapid recovery of patients.

Hepatitis B virus (HBV)-induced hepatocellular carcinoma (HCC) is one of the most frequently occurring cancers. Hepadnaviral DNA integrations are considered to be essential agents which can promote the process of the hepatocarcinogenesis. More and more researches were designed to find the relationship of the two. In this study, we investigated whether HBV DNA integration occurred at sites of DNA double-strand breaks (DSBs), one of the most detrimental DNA damage. An 18-bp I-SceI homing endonuclease recognition site was introduced into the DNA of HepG2 cell line by stable DNA transfection, then cells were incubated in patients' serum with high HBV DNA copies and at the same time, DSBs were induced by transient expression of I-SceI after transfection of an I-SceI expression vector. By using nest PCR, the viral DNA was detected at the sites of the break. It appeared that integration occurred between part of HBV x gene and the I-Scel induced breaks. The results suggested that DSBs, as the DNA damages, may serve as potential targets for bepadnaviral DNA insertion and the integrants would lead to widespread host genome changes necessarily. It provided a new site to investigate the integration.

Objective To explore the correlation of MTHFD1 gene polymorphism with genetic susceptibility to colorec-tal cancer. Methods Ninety-six cases of colorectal cancer patients and 96 cases of healthy controls were investigated by questionnaire, the polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) detection method was applied. Results Compared with normal control group, MTHFD1 G1958A polymorphism rs2236225 locus allele frequencies of patients with colorectal cancer had significant difference(P<0.05);rs2236225 genotype risk of col-orectal cancer increased 1.6 times(OR=1.603, 95%CI=0.331~2.534, P<0.05). Conclusion MTHFD1 gene polymorphism is closely related to the susceptibility of colorectal cancer, the main course of colorectal cancer is the rs2236225 gen changes in G1958A site of MTHFD1.

Objective To explore the healing pattern of condylar neck fractures by using mathematical models to simulate the dynamic changes of osteogenesis and chondrogenesis in the process of rat condylar neck fracture healing.Methods A math-ematical model was constructed to simulate the healing process of rat condylar neck fractures.The values of various parameters(mb,mc,cb and cc)generated by the model at different time points within 28 days were statistically analyzed.Subsequently,den-sity maps and growth curves of bone,cartilage,osteoblasts,and chondrocytes were fitted and the osteogenesis mode was de-duced.Results The bone area ratio simulated by the mathematical model was similar to that measured in rat fracture experi-ments(P＞0.05).The simulated density maps showed that osteogenesis was concentrated around the periosteum from day 3 to day 7 after fracture,and then concentrated in the cartilage region and gradually replaced cartilage from day 7 to day 21.The bone growth curve and cartilage growth curve were positively correlated from day 5 to day 8 and from day 21 to day 28.However,the curves were negatively correlated from day 8 to day 14 after fracture.The growth curves of osteoblasts and chondrocytes both showed an increasing trend before decreasing,with chondrocyte density peaking at day 6 and osteoblast density peaking at day 13.Conclusion The mathematical model can effectively simulate the healing process of rat condylar neck fractures and display the dynamic changes of osteogenesis and chondrogenesis during the whole process.This provides a new idea for studying healing methods of condylar neck fractures.