BACKGROUND:The anterior cruciate ligament has unique nonlinear mechanical properties under a complex physiological loading environment.Elastin is an important contributor to the mechanical properties of the anterior cruciate ligament,but its mechanical response to the anterior cruciate ligament under axial tension is not clear. OBJECTIVE:To quantitatively analyze the effect of elastin on the tensile mechanical response of the anterior cruciate ligament. METHODS:Elastase solution and control buffer were prepared.The porcine anterior cruciate ligament samples were prepared into small-size samples and randomly soaked in 0,0.1,1.0,2.0,5.0,and 10.0 U/mL elastase solution for 6 hours,and other small samples of the same size were soaked in 2 U/mL elastase solution for 0,1,3,6,9,and 12 hours.To determine suitable soaking conditions for elastin-targeted enzymes and verify the digestive effect,histological staining was used to compare the effects of enzyme treatment on tissue structure and composition.The ligament samples were randomly divided into elastase-treated group and PBS group,and immersed in 2 U/mL elastase solution and PBS buffer for 6 hours,respectively.A mechanical tensile test was performed before and after immersion. RESULTS AND CONCLUSION:(1)The biochemical results showed that being treated in 2 U/mL elastase solution for 6 hours could reduce the elastin content by 31.1%,and had no significant effect on other mechanical-related components in the tissue.(2)The histological results showed that elastase was able to penetrate the tissue,and the loose degree of tissue increased after treatment.(3)In the mechanical results before and after treatment,the mechanical properties of the PBS group decreased significantly,only the low-tension elastic modulus increased significantly and the initial length increased significantly in the elastase-treated group.(4)The intergroup comparison results showed that there was no significant difference between the two groups in pre-treatment,but the low-tension elastic modulus,initial slopes,saturated slopes,and initial length of the elastase-treated group after treatment were significantly higher than those in the PBS group.(5)These results suggest that elastin degradation significantly affects the biomechanical properties of the anterior cruciate ligament and further complements our understanding of the structure-function relationship of the anterior cruciate ligament.

Escherichia coli is a highly adaptable opportunistic pathogen bacterium that can form biofilms on the surface of implants and generates persistent cells,leading to life-threatening infections that are difficult to treat with antibiotics alone.Therefore,there is a need for an effective E.coli biofilm inhibitor to combat this public health threat.Indole is a novel quorum-sensing signaling molecule of E.coli discovered in recent years,which is of great significance in regulating bacterial growth and biofilm formation,and is a potential target for future research on new anti-biofilm preparations.This article reviews the research progress on the formation of Escherichia coli biofilms,the microbial metabolism of indole and its regulation of Escherichia coli biofilm formation,in order to provide information for clinical treatment and drug development.

Objective:To know the clinical characteristics, seasonal pattern and influencing factors of atypical depression(AD) patients.Methods:A total of 203 depressed outpatients of Peking University Sixth Hospital from January 2021 to August 2021 were included.They were assessed with demographic questionnaire, inventory of depressive symptomatology self-report(IDS-SR30) and seasonal pattern assessment questionnaire(SPAQ). According the score of IDS-SR30, all patients were classified as atypical depression(AD) and non-atypical depression(non-AD). The data were analyzed by t-test, non-parametric test and Logistic regression using SPSS 26.0 software. Results:The prevalence of AD among depressed patients was 36.0% (95% CI=29.3%-42.6%). The IDS-30 score of the AD group was (41.59±10.59), and IDS-30 score of the non-AD group was (36.08±13.17), and the difference between the two groups was statistically significant ( t=3.062, P<0.05). The global seasonal score of the AD group was 6 (3, 9), and 17.8% of the AD group had seasonal pattren.The global seasonal score of the non-AD group was 5 (3, 8), and 14.6% of the non-AD group had seasonal pattern.There was no significant difference in the global seasonal score and the proportion of seasonal pattern between the two groups ( Z=0.389, χ2=0.359, P>0.05). Depression patients who were females ( β=1.08, OR=2.95, 95% CI=1.32-6.59, P<0.05), low self-evaluation ( β=0.82, OR=2.27, 95% CI=1.12-4.59, P<0.05)and psychomotor retardation ( β=0.93, OR=2.54, 95% CI=1.33-4.85, P<0.05) were more likely to be diagnosed as AD, and depression patients having mood variation ( β=-0.94, OR=0.39, 95% CI=0.19-0.81, P<0.05) were more likely to be diagnosed as non-AD. Conclusion:Women, low self-evaluation, psychomotor retardation and unobvious mood variation can predict and help to diagnose atypical depression in depressed patients.

Objective : To investigate the effects of one night of sleep deprivation on adults ’cognitive performance and sleepiness. Methods : The study employed a repeated⁃measures design. Participants performed cognitive performance tasks , which included the Continuous Performance Test and Digit Span Test and Karolinska Sleepiness Scale. The data were analyzed using one⁃way repeated⁃measures ANOVA. Results : 48 participants were included in this study. Sleep deprivation during night shift had a adversely affect on sustained attention performance and alertness (P < 0. 05) . Compared with the beginning of night shift work , the correct number decreased , the number of errors , missed number and reaction time increased , and the score of Karolinska sleepiness scale decreased after the night shift work. The sleep deprivation has no significant effect on working memory performance (P > 0. 05) . Conclusion One night of sleep deprivation has significant deleterious effects on cognitive performance and subjec⁃ tive sleepiness. However, no effect on the working memory performances has been found.

Intestinal homeostasis is affected by many factors such as genetics, environment, and eating habits. High-fat diet, as one of the influencing factors, may affect the intestinal microbial metabolites, destroy the integrity of the intestinal mucosal barrier and induce intestinal immunity dysfunction, which in turn leads to imbalance of intestinal homeostasis and occurrence of digestive diseases. This article reviews the recent research progress on the effects of high-fat diet on intestinal homeostasis via microbial metabolites.

Objective To measure the peripheral dose distributions of the mobile head cone beam computed tomography (CBCT) and evaluate the impact of CBCT on the surrounding personnel and environment, and provide data support for clinical radiation protection management. Methods Combined with the structural characteristics of CBCT, AT1123 was used in the direction of 0° (counterclockwise), 45°, 90°, 135°, 180°, 225°, 270° and 315° in front of CBCT to measure the ambient dose equivalent rate of 30 cm, 80 cm and 130 cm away from the ground when the equipment was normally out of the beam, and the boundary of the temporary control area was drawn. At the same time, the dose level behind the lead screen 1 m away from the external surface of the equipment was measured and analyzed. Results The dose field around CBCT was symmetrically distributed with the dividing line of 0° and 180°, and the radiation dose level of 5.5 m in the direction of 0°, 3.5 m in the direction of 45°, 0.5 m in the direction of 90° and within 1.0 m in the direction of 180° (inside the "spoon" type) was higher than 2.5 μSv/h. The radiation dose levels of CT aperture 0° (straight forward), 45° and 315° behind the lead screen 1 m away from the equipment surface were 0.37 μSv/h, 0.22 μSv/h and 0.54 μSv/h, respectively. Conclusion The results show that the radiation dose around the mobile head cone beam CT is in a low dose level, the distribution of the dose field can provide necessary reference for the administrative and medical personnel to strengthen the radiation safety management. At the same time, it is suggested that lead screens should be set up in the clinical use of mobile CT to ensure the health and safety of the surrounding people and the environment.

Objective:To observe the preventive effects of infliximab in autoimmune hepatitis (AIH) and to explore its mechanism.Methods:The mice AIH model was established by injecting concanavalin A (Con-A) into the caudal vein. Forty mice were divided into prevention group and control group, with 20 mice in each group. The mice of prevention group were injected intravenously with infliximab (20 mg/kg) one hour before Con-A injection and the mice of control group were administrated with 200 μL phosphate buffered saline (PBS). Serum was collected 3, 8, 12 and 24 h after Con-A/PBS injection. The serum level of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) was detected by colorimetry. The level of cytokine interleukin (IL)-6, IL-1β, interferon gamma (IFN-γ), IL-4, IL-17A, IL-10 and chemokine C-X-C motif ligand 10 (CXCL10) was measured by enzyme-linked immunosorbent assay (ELISA). Liver samples were taken 12 h after Con-A/PBS injection for hematoxylin-eosin staining. Liver infiltrated lymphocytes were assessed by flow cytometry. The expression of T-box transcription factor 21 ( TBX21), GATA binding protein 3 ( GATA3), RAR related orphan receptor C ( RORC) and CXCL10 at mRNA level was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR). The expression of CXCL10 in liver was detected by Western blotting. Paired t test and one-way analysis of variance were used for statistic analysis. Results:At 8, 12, and 24 h after Con-A injection, the serum ALT level, AST level, IL-1β and IFN-γ of prevention group were all lower than those of control group ((545.8±190.3) U/L vs. (865.8±237.7) U/L, (947.6±267.9) U/L vs. (1 448.0±403.5) U/L, (508.6±131.1) U/L vs. (976.6±207.6) U/L; (620.7±132.0) U/L vs. (952.9±106.8) U/L, (801.6±212.0) U/L vs. (1 424.8±236.0) U/L, (632.1±117.8) U/L vs. (1 008.3±187.5) U/L; (31.38±10.12) ng/L vs. (48.12±11.53) ng/L, (39.34±11.40) ng/L vs. (60.00±14.17) ng/L, (29.49±8.22) ng/L vs. (46.89±5.50) ng/L; and (432.93±66.82) ng/L vs. (674.66±97.88) ng/L, (655.09±169.17) ng/L vs. (937.90±166.36) ng/L, (263.40±54.97) ng/L vs. (410.74±86.64) ng/L), and the differences were statistically significant ( t = 2.350, 2.308, 4.263, 4.374, 4.860, 3.806, 2.440, 2.541, 3.939, 4.560, 2.660 and 3.210; all P<0.05). The serum IL-6 levels 3, 8, 12 and 24 h after Con-A injection of prevention group were all lower than those of control group ((1 075.79±303.77) ng/L vs. (1 914.48±317.80) ng/L, (1 945.97±271.85) ng/L vs. (2 100.80±378.42) ng/L, (1 578.60±504.54) ng/L vs. (2 525.40±406.55) ng/L, (1 020.64±280.03) ng/L vs. (1 582.00±311.96) ng/L), and the differences were statistically significant ( t=4.266, 2.903, 3.267 and 2.994; all P < 0.05). At 3 h after Con-A injection, serum CXCL10 level and CXCL10 mRNA expression in liver tissues of prevention group were both lower than those of control group ((1 755.8±148.1) ng/L vs. (2 102.0±334.0) ng/L and 7.20±3.00 vs. 27.60±1.90), and the differences were statistically significant ( t=2.356 and 2.623, both P<0.05). At 3 and 8 h after Con-A injection, T- bet expression at mRNA level in liver tissues of prevention group was lower than that of control group (6.94±2.29 vs. 15.20±3.48 and 9.38±3.48 vs. 18.17±4.48), and the differences were both statistically significant ( t = 4.427 and 3.673, both P<0.05). However, 3, 8, 12 and 24 h after Con-A injection, there were no statistically significant differences in serum IL-4, IL-17A, IL-10, or GATA3 or RORC expression at mRNA level between prevention group and control group (all P > 0.05). Conclusions:Infliximab has certain preventive effects in mice AIH model, which may be achieved by antagonizing TNF-α and decreasing the expression of CXCL10 in liver, reducing the infiltration of T-helper 1 cells and CD8 + T cells into liver, and by reducing T lymphocyte activation induced by inflammatory cytokines thus alleviating the damage of T lymphocytes to hepatocytes.

Objective To investigate the relationship between aberrant expression of interleukin 6 (IL-6) and gene methylation in patients with ulcerative colitis (UC),and to clarify the mechanism of epigenetics in UC.Methods From March 2017 to March 2018,a total of 59 UC patients admitted to the Department of Gastroenterology,General Hospital Affiliated to Tianjin Medical University were enrolled,and at the same time 58 normal individuals who received health checkups were selected as healthy controls.Blood samples and colonic mucosa specimens of UC group and healthy control group were collected.DNA methyltransferase (DNMT) activity,methylation level of CpG locus in IL-6 promoter region and expression level of IL-6 were detected.Chi-square test and student's t test were performed for statistical analysis.Results The methylation level and IL-6 expression level examination were completed in 24 and 30 cases of UC group,respectively;which were detected in 21 and 20 cases of healthy control group,respectively.The activity of DNMT of UC group was significantly lower than that of healthy control group ((16.48 ± 6.17) OD · h-1 · mg-1 vs.(62.48 ± 33.88) OD · h-1 ·mg-1),and the difference was statistically significant (t =3.707,P ＜ 0.05).The ratios of methylation,partial methylation and non-methylation of UC group were 31.2％ (15/48),50.0％ (24/48) and 18.8％ (9/48),respectively,and those of healthy control group were 58.3％ (35/60),21.7％ (13/60) and 20.0％ (12/60),and the difference between the two groups was statistically significant (x2 =10.495,P ＜ 0.05).The positive expression rate of IL-6 in intestinal mucosa of UC group was higher than that of healthy control group (100.0％,21/21 vs.25.0％,5/20),and the difference was statistically significant (x2 =24.837,P ＜0.05).The serum IL-6 level of UC group was higher than that of healthy control group ((1 075.02 ±661.95) ng/L vs.(583.43 ± 425.10) ng/L),and the difference was statistically significant (t =3.245,P ＜ 0.05).Conclusion The decrease of DNMT activity in the intestinal mucosa of UC patients may reduce the methylation level of IL-6 gene promoter region,which is correlated with the increased level of IL-6 expression in the intestinal mucosa and serum,and involve in the inflammatory process of UC.

Objective: To investigate the prognostic value of albumin-to-bilirubin scores in the assessment of autoimmune hepatitis-related cirrhosis. Methods: The receiver operating characteristic curve was used to evaluate the accuracy of ALBI, Child-Pugh and model for end-stage liver disease (MELD) for prognosis prediction. Survival analysis was performed according to the ALBI classification. Spearman correlation analysis was performed on the ALBI score and the Child-Pugh score. Survival curves were plotted by Kaplan-Meier method, and Log-rank method was used to compare the survival difference curves between different groups. Results: 149 patients were recruited in the study. The ROC analysis showed that the ALBI scores (0.861, 0.826, 0.779, 0.744)was superior to Child-Pugh scores(0.703, P = 0.006; 0.672, P < 0.001; 0.613, P < 0.001; 0.583, P < 0.001)and MELD score(0.774, P = 0.031; 0.731, P = 0.007; 0.669, P < 0.001; 0.631, P < 0.001) for predicting 6, 12, 24, and 36 months mortality. Patients with ALBI grade 3 had a significantly lower survival rate than those with ALBI grade1 and grade 2. Conclusion ALBI score may be useful to evaluate the long-term prognosis of patients with autoimmune hepatitis-related cirrhosis.

Objective To explore the application value of retrobulbar nerve block combined with general anesthesia in the penetrating keratoplasty (PKP). Methods A total of 100 recipients undergoing PKP from January 2017 to January 2019 were recruited in this study. All recipients were divided into the observation group (n=50) and control group (n=50) by random number table method. In the control group, patients received laryngeal mask airway under general anesthesia, and in the observation group, patients received laryngeal mask airway under general anesthesia combined with retrobulbar nerve block. Hemodynamic changes of the PKP recipients before and after operation were observed in two groups. The dosage of analgesic drugs and the incidence of complications were observed in two groups. The degree of pain at postoperative 2-, 6- and 24-h was evaluated by visual analogue scale (VAS) in two groups. The awakening situation of the recipients in two groups was observed. The levels of inflammatory cytokines at 1 d before and after operation were statistically compared in two groups. Results The average arterial pressure and heart rate at intraoperative 15 min and after the surgery in the observation group were significantly higher than those in the control group (both P < 0.05). In the observation group, the dosage of remifentanil and propofol were (1.0±0.4) mg and (299±40) mg, significantly lower than (1.3±0.6) mg and (365±42) mg in the control group (both P < 0.05). The incidence of complications did not significantly differ between two groups (P > 0.05). In the observation group, the VAS scores at 2-, 6- and 12-h after operation were remarkably lower than those in the control group (all P < 0.01). The respiratory recovery time, eye opening time, directional force recovery time and extubation time of the recipients in the observation group were significantly shorter than those in the control group (all P < 0.05). The expression levels of including interleukin (IL)-1, IL-6 and tumor necrosis factor-α (TNF-α) at postoperative 1 d in the observation group were considerably lower than those in the control group (all P < 0.05). Conclusions Retrobulbar nerve block combined with general anesthesia can maintain hemodynamic stability during PKP, reduce the dosage of remifentanil and propofol and alleviate the degree of postoperative pain and inflammatory responses of the recipients.