Region partitioning of articular cartilage with streaming-potential-based parameters and indentation maps

Articular cartilage exhibits site-specific tissue inhomogeneity, for which the tissue properties may continuously vary across the articular surface. To facilitate practical applications such as studying site-specific cartilage degeneration, the inhomogeneity may be approximated with several distinct region-wise variations, with one set of tissue properties for one region. A clustering method was previously developed to partition such regions using cartilage indentation-relaxation and thickness mapping instead of simply using surface geometry. In the present study, a quantitative parameter based on streaming potential measurement was introduced as an additional feature to assess the applicability of the methodology with independent datasets. Experimental data were collected from 24 sets of femoral condyles, extracted from fresh porcine stifle joints, through streaming potential mapping, automated indentation, and needle penetration tests. K-means clustering and Elbow method were used to find optimal region partitions. Consistent with previous findings, three regions were suggested for either lateral or medial condyle regardless of left or right joint. The region shapes were approximately triangular or trapezoidal, which was similar to what was found previously. Streaming potentials were confirmed to be region-dependent, but not significantly different among joints. The cartilage was significantly thicker in the medial than lateral condyles. The region areas were consistent among joints, and comparable to that found in a previous study. The present study demonstrated the capability of region partitioning methods with different variables, which may facilitate new applications whenever site-specific tissue properties must be considered.

Chemokine CCL2 promotes cardiac regeneration and repair in myocardial infarction mice via activation of the JNK/STAT3 axis

Stimulation of adult cardiomyocyte proliferation is a promising strategy for treating myocardial infarction (MI). Earlier studies have shown increased CCL2 levels in plasma and cardiac tissue both in MI patients and mouse models. In present study we investigated the role of CCL2 in cardiac regeneration and the underlying mechanisms. MI was induced in adult mice by permanent ligation of the left anterior descending artery, we showed that the serum and cardiac CCL2 levels were significantly increased in MI mice. Intramyocardial injection of recombinant CCL2 (rCCL2, 1 μg) immediately after the surgery significantly promoted cardiomyocyte proliferation, improved survival rate and cardiac function, and diminished scar sizes in post-MI mice. Alongside these beneficial effects, we observed an increased angiogenesis and decreased cardiomyocyte apoptosis in post-MI mice. Conversely, treatment with a selective CCL2 synthesis inhibitor Bindarit (30 μM) suppressed both CCL2 expression and cardiomyocyte proliferation in P1 neonatal rat ventricle myocytes (NRVMs). We demonstrated in NRVMs that the CCL2 stimulated cardiomyocyte proliferation through STAT3 signaling: treatment with rCCL2 (100 ng/mL) significantly increased the phosphorylation levels of STAT3, whereas a STAT3 phosphorylation inhibitor Stattic (30 μM) suppressed rCCL2-induced cardiomyocyte proliferation. In conclusion, this study suggests that CCL2 promotes cardiac regeneration via activation of STAT3 signaling, underscoring its potential as a therapeutic agent for managing MI and associated heart failure.

[Quality control of perioperative management after radical surgery for locally advanced gastric cancer]

Gastric cancer is a common malignant tumor in China. Most gastric cancer patients are already in the locally advanced stage when they seek medical treatment. Radical surgery is the main treatment for gastric cancer. The quality control of postoperative perioperative management is of great significance in improving the surgical treatment effect and the quality of life of patients. This article systematically summarizes seven aspects, including diet and nutrition management, antimicrobial drug management, pain management, prophylactic anticoagulation management, airway management, postoperative complication management, and discharge and follow-up management, establishes clear quality standards, and achieves the goals of reducing postoperative complications, standardizing perioperative medication use, reducing hospitalization time and costs, thereby reducing patient burden and improving the economic and social benefits of medical institutions.

Alteration in ACL loading after total and partial medial meniscectomy

Anterior cruciate ligament (ACL) injuries are often caused by high impact loadings during competitive sports but may also happen during regular daily activities due to tissue degeneration or altered mechanics after a previous knee injury or surgery such as meniscectomy. Most existing research on ACL injury has focused on impact loading scenarios or the consequence of ACL injury on meniscus. The objective of the present study was to investigate the effects of varying degrees of medial meniscectomy on the mechanics of intact ACL by performing a poromechanical finite element analysis under moderate creep loadings. Four clinical scenarios with 25%, 50%, 75% and total medial meniscectomy were compared with the intact knee finite element model. Our results suggested that different medial meniscal resections may increase, at different extents, the knee laxity and peak tensile stress in the ACL, potentially leading to collagen fiber fatigue tearing and altered mechanobiology under normal joint loadings. Interestingly, the ACL stress actually increased during early knee creep (~ 3 min) before it reached an equilibrium. In addition, meniscectomy accelerated ACL stress reduction during knee creep, transferred more loading to tibial cartilage, increased contact pressure, and shifted the contact center posteriorly. This study may contribute to a better understanding of the interaction of meniscectomy and ACL integrity during daily loadings.

[Circ_0026134 regulates the miR-1270/GRB2 pathway to affect the radiosensitivity of hepatoma cells]

Objective: To investigate whether circular RNA 0026134 (circ_0026134) affects the radiosensitivity of hepatoma cells by regulating the miR-1270/growth factor receptor-bound protein 2 (GRB2) pathway. Methods: Real-time quantitative PCR (RT-qPCR) was used to detect the expression levels of circ_0026134, miR-1270, and GRB2 in liver cancer tissues and cells. Bioinformatics analysis, a dual-luciferase gene reporter assay, RT-qPCR, and western blot were used to analyze the targeting relationships between circ_0026134 and miR-1270 and miR-1270 and GRB2. The effects of circ_0026134, miR-1270, and GRB2 expression combined with 6 Gy on the proliferation, invasion, migration, and apoptosis of Huh7 and SK-HEP-1 cells were detected by a cell counting kit, a transwell assay, a scratch assay, and flow cytometry. The tumorigenesis experiment was used to detect the effect of silencing circ_0026134 in nude mice. Measurement data are expressed as the mean ± standard deviation. The independent sample t-test was used for comparison between two groups, and the one-way analysis of variance and SNK-q test were used for comparison between multiple groups. P < 0.05 was considered statistically significant. Results: The expression levels of circ_0026134 and GRB2, Huh7, and SK-HEP-1 cells in liver cancer tissues were significantly increased, while the expression levels of miR-1270 were significantly decreased (P < 0.05). The expression of circ_0026134 in Huh7 and SK-HEP-1 decreased significantly after radiotherapy (P < 0.05). circ_0026134 binds directly to miR-1270 and negatively regulates miR-1270 expression (P < 0.05). miR-1270 binds directly to GRB2 and negatively regulates GRB2 expression (P < 0.05). 6 Gy radiation significantly inhibited the proliferation, migration, and invasion of Huh7 and SK-HEP-1 cells and induced apoptosis (P < 0.05). Silencing circ_0026134 or overexpression of miR-1270 significantly enhanced the anti-proliferation, anti-migration, invasion, and pro-apoptosis effects of 6 Gy treatment on hepatoma cells (P < 0.05). Inhibition of miR-1270 significantly weakened the effects of silencing circ_0026134 combined with 6 Gy radiation on proliferation, migration, invasion, and apoptosis of hepatoma cells (P < 0.05). Overexpression of GRB2 significantly weakened the effects of miR-1270 overexpression combined with 6 Gy radiation on proliferation, migration, invasion, and apoptosis of hepatoma cells (P < 0.05). circ_0026134 knockdown significantly delayed tumor growth in vivo (P < 0.05). Conclusion: Silencing circ_0026134 strengthens radiation treatment's anti-proliferation, anti-migration, invasion, and pro-apoptotic effects in hepatoma cells by negatively regulating the miR-1270/GRB2 pathway, thereby enhancing radiosensitivity.

[Analysis of the association between diurnal temperature difference and relative humidity and myocardial infarction in Shantou residents]

Objective: To analyze the effect of meteorological conditions on mortality and population susceptibility of patients with acute myocardial infarction (AMI) in the Shantou area and to provide a scientific basis for the local public health system to prevent AMI. Methods: The AMI mortality data recorded in the resident cause of death surveillance database of Shantou from January 1, 2015, to December 31, 2020, were collected and the distribution lag nonlinear model was used to analyze the diurnal temperature range (DTR) and relative humidity (RH) on AMI mortality and the lag effect. Results: There were 13 932 deaths due to AMI in Shantou during the study period, with a male-to-female sex ratio of 1.3∶1. There was a significant association between high diurnal temperature difference exposure and low RH exposure and AMI deaths, with both single-day lag effects appearing and reaching a maximum at lag 2 day (RR=1.019, 95%CI: 1.000-1.039; RR=1.018, 95%CI: 1.003-1.034); the cumulative lag effect was all maximal at lag 0-14 day (RR=1.199, 95%CI: 1.025-1.401; RR=1.279, 95%CI: 1.117-1.465). The elderly (≥75 years) and female populations were susceptible to high DTR exposure and low RH exposure conditions. Conclusions: There was a significant association between DTR and RH and mortality of AMI in Shantou with a significant lag in their effects. Both female and elderly populations ≥75 years old were susceptible populations under high DTR and low RH exposure conditions.

Characterizing site-specific mechanical properties of knee cartilage with indentation-relaxation maps and machine learning

Knee cartilage experiences site-specific focal lesion and degeneration, which is likely associated with tissue inhomogeneity and nonuniform mechanical stimuli in the joint, for which a complete picture remains to be depicted. The present study aimed to develop a methodology to quantify knee cartilage inhomogeneity using porcine knee specimens. Automated indentation-relaxation and needle probing were performed on fully intact cartilage to obtain data that essentially represent continuous distributions of cartilage properties in the knee. Machine learning was then introduced to approximate the tissue inhomogeneity with several regions via clusters of indentation locations, and finite element modeling was used to obtain poromechanical properties for each region using indentation-relaxation and thickness data. Significant region dependence was established from the full time-dependent mechanical response. Seventeen regions, or clusters, were found to best approximate the site-specific poromechanical properties of articular cartilage for femoral groove, lateral and medial condyles and tibial plateaus, after up to eight clusters were tested for each of the five cartilage sections. The region partitions recommended, and tissue properties acquired would facilitate implementation of tissue inhomogeneity in future applications, e.g., contact modeling of the knee joint. The results obtained from 14 porcine knees revealed interesting region differences, for example, the two condyles have the same effective stiffness when responding to slowly applied mechanical loadings but substantially lower stiffness in the medial condyle when responding to fast loadings. This mechanical behavior may be associated with the fact that medial femoral cartilage is more prone to focal lesions than the lateral one.

[Surgical site infection after colorectal surgery in China from 2018 to 2020]

Objective: This study aims to survey the incidence of surgical site infection (SSI) in China and to analyze its risk factors, so as to prevent and control SSI after colorectal surgery. Methods: An observative study was conducted. Based on a program of Chinese SSI Surveillance from 2018 to 2020, the clinical data of all adult patients undergoing colorectal surgery during this time period were extracted. These included demographic characteristics and perioperative clinical parameters. Minors, pregnant women, obstetric or gynecological surgery, urological system surgery, retroperitoneal surgery, resection of superficial soft tissue masses, and mesh or other implants were excluded. A total of 2122 patients undergoing colorectal surgery from 50 hospitals were included, including 1252 males and 870 females. The median age was 63 (16) years and the median BMI was 23 (4.58) kg/m². The primary outcome was the incidence of SSI within 30 days after colorectal surgery. The secondary outcomes were mortality within 30 days postoperatively, length of ICU stays and postoperative hospital stays, and cost of hospitalization. Patients were divided into the SSI group and non-SSI group based on the occurrence of SSI. Multivariable logistic regression was performed to analyze risk factors of SSI after colorectal surgery, and subgroup analysis was conducted for open and laparoscopic surgery. Results: The incidence of SSI after colorectal surgery was 5.6% (119/2122), including 47 cases (47/119, 39.5%) with superficial incisional infections, 24 cases (24/119, 20.2%) with deep incisional infections, and 48 cases (48/119, 40.3%) with organ/space infections. The occurrence of SSI significantly increased mortality [2.5% (3/119) vs. 0.1%(3/2003), χ²=22.400, P=0.003], the length of ICU stay [0 (1) day vs. 0(0) day, U=131 339, P<0.001], postoperative hospital stay [18.5 (12.8) days vs. 9.0 (6.0) days, U=167 902, P<0.001], and medical expenses [75 000 (49 000) yuan vs. 60 000 (31 000) yuan, U=126 189, P<0.001] (P<0.05). Multivariate analysis revealed that hypertension (OR=1.782, 95%CI: 1.173-2.709, P=0.007), preoperative albumin level (OR=1.680, 95%CI: 1.089-2.592, P=0.019), a contaminated or infected incision (OR= 1.993, 95%CI: 1.076-3.689, P=0.028), emergency surgery (OR=2.067, 95%CI: 1.076-3.972, P=0.029), open surgery (OR=2.132, 95%CI: 1.396-3.255, P<0.001), and surgical duration (OR=1.804, 95%CI: 1.188-2.740, P=0.006) were risk factors for SSI, while preoperative skin preparation (OR=0.478, 95%CI: 0.310-0.737, P=0.001) was a protective factor for SSI. Subgroup analysis was performed on patients undergoing open or laparoscopic surgery. The incidence of SSI in the open surgery group was 10.2%, which was significantly higher than that in the laparoscopic or robotic group (3.5%, χ²=39.816, P<0.001). Subgroup analysis identified that a contaminated or infected incision (OR=2.168, 95%CI: 1.042-4.510, P=0.038) and surgical duration (OR=2.072, 95%CI: 1.171-3.664, P=0.012) were risk factors for SSI after open surgery, while mechanical bowel preparation (OR=0.428, 95%CI: 0.227-0.807, P=0.009) and preoperative skin preparation (OR=0.356, 95%CI: 0.199-0.634, P<0.001) were protective factors for SSI after open surgery. In laparoscopic surgery, diabetes mellitus (OR= 2.292, 95%CI: 1.138-4.617, P=0.020) and hypertension (OR=2.265, 95%CI: 1.234-4.159, P=0.008) were risk factors for SSI. Conclusions: The incidence of SSI after colorectal surgery is 5.6%. Minimally invasive surgery should be selected to reduce the occurrence of postoperative SSI. To prevent the occurrence of SSI after open surgery, skin preparation and mechanical bowel preparation should be performed before the operation, and the duration of the operation should be shortened as much as possible. In the perioperative period, care of patients with hypertension, diabetes, and contaminated or infected incisions should be given particular attention.

[Pediatric pancreatic lesions: a clinicopathological analysis of 42 cases]

Objective: To investigate the clinicopathological characteristics of pancreatic lesions in children. Methods: The clinicopathological data of pancreatic lesions in children were analyzed including 42 cases of pancreatic tumors diagnosed from January 2000 to May 2021 in Guangzhou Women's and Children's Medical Center, Guangzhou, China. Histological and immunohistochemical assessments were performed. Related literature was reviewed. Results: The 42 pediatric patients with pancreatic lesions aged 1 day to 12 years (mean, 4.25 years). There were 23 males and 19 females. Clinical presentations included abdominal masses, abdominal pain, vomiting and persistent hypoglycemia after birth. Ultrasound and computerized tomography examination showed space-occupying pancreatic lesions in 31 cases, but no detectable pancreatic lesions in 11 cases. Histologically, among the 42 cases, 22 cases (52.4%) were neoplastic, including 18 cases of epithelial origin. Nine cases of pancreatoblastoma showed that the epithelial tumor cells were arranged in a trabecular pattern, with squamous nests. Six cases of solid-pseudopapillary tumors revealed hemorrhagic and necrotic cysts and monomorphic epithelioid cells arranged in solid sheets, nests or pseudopapillae. Two cases of neuroendocrine tumors showed tumor cells arranged in cords or nests; one case had a mitotic count of about 3/10 high power field, and a Ki-67 index of about 5%, which was consistent with G2 neuroendocrine tumor; the other case showed tumor cells with cytological atypia, brisk mitoses, about 25/10 HPF and a Ki-67 index of about 80%, consistent with small-cell type neuroendocrine carcinoma. The case of acinar cell carcinoma showed high cellularity, tumor cells in solid, cord-like or acinar-like arrangement with little stroma, and monotonous tumor cells with single distinct nucleolus. There were 4 cases of mesenchymal tumors, including 3 cases of Kaposi's hemangioendothelioma and 1 case of inflammatory myofibroblastic tumor. Among the 20 cases (47.6%) of non-neoplastic lesions, there were 11 cases of hyperinsulinism with ATP-sensitive potassium channel abnormality (HAPCA). Severn cases of diffuse type HAPCA in which the islets scattered between the pancreatic acinar tissue, enlarged, and prominent nuclei. Three cases of focal type HAPCA showed pancreatic islet hyperplasia in the form of nested nodules (0.6-1.5 cm). One case of atypical type HAPCA had extensive islet hyperplasia in pancreatic tissue, and scattered proliferation of nest-like nodules was noted. There were also 7 cases of pseudocyst and 2 cases of congenital cyst. Immunohistochemically, pancreatoblastomas were diffusely positive for CKpan, CK8/18, and β-catenin (nuclear staining of squamous nests only). Solid-pseudopapillary tumors expressed CD10, cyclin D1, CD99, vimentin, CD56, and β-catenin (nuclear staining). Neuroendocrine tumors were positive for CK, Syn, NSE, CgA, CD56, and β-catenin (membranous staining). The acinar cell carcinoma was positive for CK8/18, trypsin, and β-catenin (membranous staining). Conclusions: Pancreatic lesions in children have a wide range of histopathological types. HAPCA is the most common lesion of newborns. Pediatric pancreatic tumors are rare and mostly malignant. It is important to recognize them and make correct pathological diagnoses.

[Progress in health effects and measurement standards of ultraviolet radiation in the workplace]

Ultraviolet radiation affects human health. On the one hand, moderate amounts of UV radiation can promote human health and have the effect of promoting vitamin D production; but on the other hand, excessive UV radiation can also cause adverse effects on human skin and eyes, such as causing skin photoaging, skin cancer, electrophthalmia and cataracts to occur. Therefore, the measurement of ultraviolet radiation is extremely important. This paper mainly reviews the health effects of ultraviolet radiation and the progress of measurement standards in the workplace, and puts forward suggestions on the revision of the existing standards from five aspects including use new measuring instruments and methods, improve the existing measuring instruments, specify the number of measurements, expand the scope of application of the standards and consider the influence of the sun on the measurement of artificial ultraviolet radiation, so as to provide reference for the revision of new standards.

Creep behavior of human knee joint determined with high-speed biplanar video-radiography and finite element simulation

Creep and relaxation of knee cartilage and meniscus have been extensively studied at the tissue level with constitutive laws well established. At the joint level, however, both experimental and model studies have been focused on either elastic or kinematic responses of the knee, where the time-dependent response is typically neglected for simplicity. The objectives of this study were to quantify the in-vivo creep behavior of human knee joints produced by the cartilaginous tissues and to use the relevant data to validate a previously proposed poromechanical model. Two participants with no history of leg injury volunteered for 3T magnetic resonance imaging (MRI) of their unloaded right knees and for biplanar video-radiography (BVR) of the same knees during standing on an instrumented treadmill for 10 min. Approximately 550 temporal data points were obtained for the in-vivo displacement of the right femur relative to the tibia of the knee. Models of the bones and soft tissues were derived from the MRI. The bone models were used to reconstruct the 3D bone kinematics measured using BVR. Ground reaction forces were simultaneously recorded for the right leg, which were used as input for the subject-specific finite element knee models. Cartilaginous tissues were modeled as fluid-saturated fibril-reinforced materials. In-vivo creep of the knee was experimentally observed for both participants, i.e., the joint displacement increased with time while the reaction forces at the foot were approximately constant. The creep displacements obtained from the finite element models compared well with the experimental data when the tissue properties were calibrated (Pearson correlation coefficient = 0.99). The results showed the capacity of the poromechanical knee model to capture the creep response of the joint. The combined experimental and model study may be used to understand the fluid-pressure load support and contact mechanics of the joint using material properties calibrated from the displacement data, which enhance the fidelity of model results.

[Gonadal neoplastic related lesions in children with disorders of sexual development: a clinicopathological study of twelve cases]

Objective: To investigate the clinicopathological features of gonadal neoplastic related lesions in children with disorders of sexual development (DsD). Methods: The clinical manifestations, chromosomal karyotype, histology and immunophenotype of 12 cases of neoplastic related lesions from Guangzhou Women and Children's Medical Center, Guangzhou were analyzed during Jan 2015 to May 2020. Results: Twelve cases of neoplastic related lesions were screened in 205 cases of DsD, and 6 patients with gonadal germ cell neoplasia aged 3-13 years with an average age of 8.3 years. There were 2 males and 4 females. Clinical features showed malformation of external genitalia in 2 cases, short stature in 2 cases, clitoral enlargement in 1 case, lower abdominal pain and a huge pelvic mass in 1 case. Chromosomal karyotyping of peripheral blood showed 2 cases of 46XY and 4 cases of 45X/46XY. Fourteen gonadal specimens were examined. Microscopically, 1 case showed dysgerminoma in left ovary, and malignant mixed germ cell tumors in right ovary, as well as gonadoblastoma (GB) and undifferentiated gonadal tissue (UGT). The remaining 5 cases were all precursor lesions of germ cell tumor. Six specimens showed GB, 3 of UGT, and 3 specimens showed germ cell neoplasia in situ (GCNIS), one of which was accompanied by intratubular seminoma and 1 was GB with GCNIS. The other 6 patients with DsD were aged from 8 months to 2 years and 5 months, including 5 males and 1 females. Clinical manifestations showed 5 cases of hypospadias and 1 case of bilateral indirect inguinal hernia. Microscopically, 6 cases showed maturation delay of gonocytes in seminiferous tubules. Immunohistochemically, the primordial germ cells/gonocytes expressed OCT3/4, PLAP and c-KIT in the 12 cases. Conclusion: Gonadal neoplasia in children with DsD is mainly precursor lesions of germ cell tumor and improved understanding of these lesions is of great significance.

[A multi-center retrospective study of perioperative chemotherapy for gastric cancer based on real-world data]

Objective: To explore the effect of perioperative chemotherapy on the prognosis of gastric cancer patients under real-world condition. Methods: A retrospective cohort study was carried out. Real world data of gastric cancer patients receiving perioperative chemotherapy and surgery + adjuvant chemotherapy in 33 domestic hospitals from January 1, 2014 to January 31, 2016 were collected. Inclusion criteria: (1) gastric adenocarcinoma was confirmed by histopathology, and clinical stage was cT2-4aN0-3M0 (AJCC 8th edition); (2) D2 radical gastric cancer surgery was performed; (3) at least one cycle of neoadjuvant chemotherapy (NAC) was completed; (4) at least 4 cycles of adjuvant chemotherapy (AC) [SOX (S-1+oxaliplatin) or CapeOX (capecitabine + oxaliplatin)] were completed. Exclusion criteria: (1) complicated with other malignant tumors; (2) radiotherapy received; (3) patients with incomplete data. The enrolled patients who received neoadjuvant chemotherapy and adjuvant chemotherapy were included in the perioperative chemotherapy group, and those who received only postoperative adjuvant chemotherapy were included in the surgery + adjuvant chemotherapy group. Propensity score matching (PSM) method was used to control selection bias. The primary outcome were overall survival (OS) and progression-free survival (PFS) after PSM. OS was defined as the time from the first neoadjuvant chemotherapy (operation + adjuvant chemotherapy group: from the date of operation) to the last effective follow-up or death. PFS was defined as the time from the first neoadjuvant chemotherapy (operation + adjuvant chemotherapy group: from the date of operation) to the first imaging diagnosis of tumor progression or death. The Kaplan-Meier method was used to estimate the survival rate, and the Cox proportional hazards model was used to evaluate the independent effect of perioperative chemo therapy on OS and PFS. Results: 2 045 cases were included, including 1 293 cases in the surgery+adjuvant chemotherapy group and 752 cases in the perioperative chemotherapy group. After PSM, 492 pairs were included in the analysis. There were no statistically significant differences in gender, age, body mass index, tumor stage before treatment, and tumor location between the two groups (all P>0.05). Compared with the surgery + adjuvant chemotherapy group, patients in the perioperative chemotherapy group had higher proportion of total gastrectomy (χ(2)=40.526, P<0.001), smaller maximum tumor diameter (t=3.969, P<0.001), less number of metastatic lymph nodes (t=1.343, P<0.001), lower ratio of vessel invasion (χ(2)=11.897, P=0.001) and nerve invasion (χ(2)=12.338, P<0.001). In the perioperative chemotherapy group and surgery + adjuvant chemotherapy group, 24 cases (4.9%) and 17 cases (3.4%) developed postoperative complications, respectively, and no significant difference was found between two groups (χ(2)=0.815, P=0.367). The median OS of the perioperative chemotherapy group was longer than that of the surgery + adjuvant chemotherapy group (65 months vs. 45 months, HR: 0.74, 95% CI: 0.62-0.89, P=0.001); the median PFS of the perioperative chemotherapy group was also longer than that of the surgery+adjuvant chemotherapy group (56 months vs. 36 months, HR=0.72, 95% CI:0.61-0.85, P<0.001). The forest plot results of subgroup analysis showed that both men and women could benefit from perioperative chemotherapy (all P<0.05); patients over 45 years of age (P<0.05) and with normal body mass (P<0.01) could benefit significantly; patients with cTNM stage II and III presented a trend of benefit or could benefit significantly (P<0.05); patients with signet ring cell carcinoma benefited little (P>0.05); tumors in the gastric body and gastric antrum benefited more significantly (P<0.05). Conclusion: Perioperative chemotherapy can improve the prognosis of gastric cancer patients.

[Research on mental health status of medical staff during COVID-19 epidemic]

Objective: To explore the psychological status of medical staff during COVID-19 epidemic, so as to provide reference and scientific basis for carrying out further psychological intervention and ensuring the mental health of medical staff. Methods: By using convenient sampling method and the Stresss-Anxiety ubscale of Depression Anxiety Stress (DASS-21) , the mental health status of 615 medical staff was investigated by the way of questionnaire star from February 4 to 16, 2020. A total of 615 questionnaires were distributed and collected, and 615 were valid, with an effective recovery rate of 100%. Results: The detection rates of psychological stress and anxiety of medical staff were 13.82% (85/615) and 25.37% (156/615) , respectively. 31-40 years old and working in key departments were risk factors for psychological stress of medical staff (OR=1.779, 2.127) ; Women, frequently washing hands with soap/hand sanitizer/disinfectant were protective factors for psychological stress (OR=0.520, 0.528) . Medical staff working in designated hospitals and key departments were more likely to have anxiety (OR=2.042, 2.702) ; The high fit of the mask to the face and bridge of the nose was a protective factor for the psychological anxiety of medical staff (OR=0.500) . Conclusion: Medical staff show higher stress and anxiety during the epidemic of COVID-19. Psychological intervention should be carried out early, focusing on men, age 31 to 40, medical staff working in designated hospitals and key departments.

[Clinical analysis of five cases of autism spectrum disorder complicated with epilepsy with chromosome copy number variation]

Objective: To explore the clinical features and genetic causes of autism spectrum disorder (ASD) patients with epilepsy. Methods: The clinical data of five patients with ASD and epilepsy admitted to Xuanwu Hospital between September 2017 and September 2018 were collected, including medical history, intelligence level, developmental level, physical examination, neuroimaging and electroencephalogram. High-throughput whole-genome sequencing was applied to five patients and their parents. Results: Of five patients, four were male and one was female. All five patients had mild mental retardation, and one patient had significant growth retardation and craniofacial deformity. The average epilepsy onset age was 6.3 years old (7 months to 16 years). The main epileptic type was tonic-clonic seizure with abnormal EEG results. All patients have a favorable response to anti-epileptic drugs. Whole-exome sequencing (WES) revealed copy number variation in all 5 patients. Among them, 3 cases were reported to be pathogenic, and 2 cases were not reported (chromosome 16p13.3 duplication and chromosome 21q22.3 deletion). Conclusions: The results of current study support that autism spectrum disorders with seizures is often associated with copy number variations, such as Williams-Beuren region duplication syndrome, chromosome 15q11.2 duplication syndrome and chromosome 15q11.2 deletion syndrome. We reported two novel copy number variations (chromosome 16p13.3 duplication and chromosome 21q22.3 deletion) in two autism spectrum disorder patients with epileptic seizures.

[Clinical features and gene analysis of TBC1D24 gene mutation related early-onset focal myoclonic epilepsy]

Objective: To investigate the clinical features and genetic characteristics of patients with TBC1D24 gene mutation related early-onset focal myoclonic epilepsy. Methods: Clinical data of 3 patients with TBC1D24 gene mutation related early-onset focal myoclonic epilepsy of Xuanwu Hospital from November 2016 to June 2017 was collected and analyzed.Candidate gene mutations were screened by second generation sequencing. Results: Among the 3 patients, 1 was male and 2 were females.Seizure onset age was 4 months, 3 years and 5 years after birth respectively. Two patients had family history of epilepsy.They all had prolonged episodes of focal myoclonus. Two patients had mental retardation.Scalp electroencephalograms (EEG) was recorded in all 3 cases and myoclonic seizures were captured.The ictal EEGs were normal in all cases. In one patient, the ictal EEG of generalized seizure showed alpha rhythm originating from left fronto-central region. Brain magnetic resonance imaging (MRI) was normal in 2 patients. Abnormal signal was found bilaterally in cerebellum in 1 patient. The gene screening showed that two patients carried compound heterozygous mutation of TBC1D24 gene and one carried homozygous mutation, all of which were de novo mutations.All the patients were treated with multiple antiepileptic drugs (AEDs) and seizures were uncontrolled in 2 patients. One patient was followed up for 10 months without recurrence. Conclusions: TBC1D24 gene related early-onset focal myoclonic epilepsy is clinically characterized by early onset, prolonged focal myoclonus which relieved with sleep, mental retardation and poor response to AEDs.The interictal and ictal EEG usually show normal. Genetic analysis can assist in diagnosis and genetic counseling.

[Pathologic features on gonadal changes of sexual developmental disorders in children]

Objective: To investigate the pathologic features of gonadal tissues of disorders of sexual development (DSD) in children. Methods: Fifty-three cases of gonadal developmental disorders were collected from July 2015 to August 2017 at Guangzhou Women and Children's Medical Center. Clinical manifestations, karyotypes, sex hormone levels, ultrasound imaging, histology and immunophenotype of gonadal tissues were analyzed. Results: The age of patients ranged from 7 months to 17 years with an average of (50.7 ± 47.1) months. Social genders of the patients included 32 males and 21 females. Forty-eight patients had abnormal sex hormone levels. Clinical presentations included: toward female genitalia in 25 cases, male genitalia tendency in 17 cases and ambiguous external genitalia in 11 cases. Hypospadias was seen in 31 cases and short stature was seen in 8 cases. Chromosomal karyotyping of peripheral blood revealed 23 cases of sex chromosome disorders, 22 cases of 46 XY disorders, of which 3 cases were 5α-reductase deficiency and 8 cases of 46 XX disorders. Ultrasound examination showed cryptorchidism in 30 cases, including 16 cases of unilateral, 14 cases of bilateral and 1 case presenting a huge pelvic tumor. A total of 97 gonadal tissues from 53 cases of DSD were examined, including 9 cases of unilateral and 44 cases of bilateral gonads. Microscopically, 55 gonads (56.7%) showed dysplastic testes including 17 unilateral and 19 bilateral gonads. Fourteen were streak gonads (14.4%) including 8 unilateral and 3 bilateral gonadal tissues. Nine streak gonad with epithelial cord-like structures (9.3%) were found, of which 5 were unilateral and 2 were bilateral lesions. Seven gonads were ovotestis (7.2%), unilateral in 5 cases (the other side of the gonads of ovary in 4 cases, 1 case of dysplastic testes) and bilateral in 1 case. Seven gonads showed follicular-rich ovarian tissue (7.2%). One case showed bilateral dysplastic testes with gonadoblastoma and ectopic adrenal cortex. One case of streak gonad showed epithelial cord-like structures and undifferentiated glandular tissue embedded in malignant mixed germ cell tumors (mixed gonadoblastoma, dysgerminoma, mature teratoma and yolk sac tumor). One case had testicular microlithiasis. Uterus and fallopian tube structures were found in 11 cases. Immunohistochemical stains were performed in 15 cases. D2-40, PLAP and CKIT were expressed in germ cells and Calretinin, WT1 and inhibin were positive in Setoli cells. SALL4 and OCT3/4 were positive in 3 cases. Inhibin highlighted interstitial Leydig cells in 2 cases. GPC3 was positive in yolk sac tumor component. Conclusions: Gonadal dysgenesis presents a broad spectrum of gonadal phenotypes with variable degrees of differentiation. The development of bilateral gonadal tissues has certain variability. Chromosomal karyotypes have no correlation with gonadal phenotypes. Accurate histopathologic diagnosis of gonadal dysgenesis plays an important role in the treatment and prognosis of the patient.

[Establishment and evaluation of noninvasive diagnostic models for liver fibrosis in patients with chronic hepatitis B]

Objective: To establish the model of liver fibrosis based on noninvasive indices, and to investigate the diagnostic value of this model. Methods: A total of 838 patients with chronic hepatitis B (CHB) who underwent liver biopsy in our hospital from March 2003 to October 2013 were selected, and the results of blood tests and B-ultrasound were collected. The correlation between these indices and liver fibrosis stage was analyzed. A logistic regression analysis was performed to establish a predictive model, and the value of this model was examined in validation group. The t-test, Mann-Whitney U non-parametric test, and chi-square test were used for data analysis. A Spearman rank correlation analysis was used for bivariate correlation analysis, and a dichotomous logistic stepwise regression analysis was used for multivariate analysis. Results: In the model group, a model (FV) consisting of age, platelet count (PLT), γ-glutamyl transferase (GGT), albumin/globulin ratio (A/G), and splenic square area (SSA) was established. The areas under the receiver operating characteristic curve (AUROCs) of the model FV were 0.892, 0.910, and 0.915, respectively, in diagnosing significant liver fibrosis (S2-4), progressive liver fibrosis (S3-4), and early-stage liver cirrhosis (S4), with sensitivities of 77.6%, 83.7%, and 86.0%, respectively, specificities of 89.7%, 84.5%, and 83.7%, respectively, and accuracy of 82.1%, 84.2%, and 84.2%, respectively. There were no significant differences in AUROCs between the validation group and the model group (Z = 0.360, 0.885, and 0.046, all P > 0.05). In all patients, FV had significantly higher AUROCs in the diagnosis of liver fibrosis than FIB4 index and S index (Z = 4.569/3.423, 5.640/4.709, and 4.652/4.439, all P < 0.05). With < 0.374 and ≥ 0.577 as the cut-off values for the exclusion and diagnosis of significant liver fibrosis, 61.1% (512/838) of all patients could avoid liver biopsy, and the accuracy was 92.6% (474/512). Conclusion: The noninvasive model based on age, PLT, GGT, A/G, and SSA can accurately predict liver fibrosis degree in patients with CHB with good reproducibility; therefore, it can be used for dynamic monitoring of liver fibrosis degree in clinical practice.

[Analysis of gene mutation and clinical characteristics in patients with idiopathic epilepsy]

Objective: To explore the association between gene mutations and clinical characteristics in Chinese patients with epilepsy. Methods: A total of twenty-three patients with idiopathic epilepsy admitted to the Xuanwu Hospital of Capital Medical University from January 2014 to July 2016 were included.The age at onset of epilepsy ranged from 8 months to 31 years.All patients were screened for mutations by next-generation of sequencing (NGS), using a targeted capture panel of epilepsy and related seizures to screen forgene causative for or related to epilepsy.Some mutations were verified for inheritance by Sanger sequencing of two generations in the family.The differences in clinical characteristics among different mutation carriers were compared. Results: A total of 38 mutations were identified in 23 patients.Most of the patients presented with tonic-clonic seizures, and most were not accompanied by mental retardation.Causative genes were dominated by those encoding ion channel, enzyme and proteins with special functions.Although mutation carriers for genes encoding ion channel proteins and those with special functions were not significantly different in age at onset, types of seizure, family history or complications(P>0.05), patients presenting with tonic-clonic seizures had higher frequency of mutations in genes encoding ion channel (15/15)than those encoding proteins with special function(16/20)(P=0.066). Conclusions: NGS is a useful technology in detecting mutations in patients with various types of epilepsy and aiding in etiological diagnosis of the disease.Tonic-clonic seizures may correlate with mutations in genes encoding ion channel.

[Progress of research in relation to the impact of climate change on children's health status]

Along with global warming, climate change has become one of the biggest public health challenges. The unique metabolism, behavior, physiology and development in children, will make them suffer more from the climate change. In the present review, we summarized the progress and situation of studies on the associations between climate change and children's health also trying to provide adaptation and mitigation strategies. The purpose of this study was to offer scientific evidence for prevention and control on the adverse effects as injuries, diseases and deaths among children that resulted from the changes of climate.

Remote ischemic conditioning for the prevention of contrast-induced acute kidney injury in patients undergoing intravascular contrast administration: a meta-analysis and trial sequential analysis of 16 randomized controlled trials

Objective

We conducted this meta-analysis to examine the effect of remote ischemic conditioning (RIC) on contrast-induced acute kidney injury (CI-AKI) in patients undergoing intravascular contrast administrationon.

Methods

Pubmed, Embase, and Cochrane Library were comprehensively searched to identify all eligible studies by 15th March, 2017. Risk ratio (RR) and weighted mean difference with the corresponding 95% confidence intervals (CI) were used to examine the treatment effect. The heterogeneity and statistical significance were assessed with Q-test and Z-test, respectively.

Results

A total of 16 RCTs including 2175 patients were eventually analyzed. Compared with the control group, RIC could significantly decrease the incidence of CI-AKI (RR=0.58; 95% CI: 0.46, 0.74; P < 0.001), which was further confirmed by the trial sequential analysis. Subgroup analyses showed that remote ischemic preconditioning (RIPrC) and remote ischemic postconditioning (RIPoC) were both obviously effective, and perioperative hydration might enhance the efficiency of RIC. RIC also significantly reduced the major adverse cardiovascular events within six months.

Conclusion

RIC, whether RIPrC or RIPoC, could effectively exert renoprotective role in intravascular contrast administration and reduce the incidence of relevant adverse events.

[An investigation on job burnout of medical personnel in a top three hospital]

OBJECTIVE

To investigate job burnout status of medical Personnel in a top three hospitals, in order to provide basic data for intervention of the hospital management.

METHODS

A total of 549 doctors and nurses were assessed by Maslach Burnout Inventory-Human Service Survey (MBI-HSS). SPSS 19.0 software package was applied to data description and analysis, including univariate analysis and orderly classification Logistic regression analysis.

RESULTS

The rate of high job burnout of doctors and nurses are 36.3% and 42.8% respectively. Female subjects got higher scores (29.4±13.5) on emotional exhaustion than male subjects (26.2±12.8) compared with.Doctors got lower scores (28.2±15.9) on emotional exhaustion and higher scores (31.4±9.3) on personal accomplishment than nurses.Compared with subjects with higher professional title, young subjects with primary professional title got lower scores on personal accomplishment.Subjects with 11-20 years working age got the highest scores on depersonalization.Among all the test departments, medical personnel of emergency department got the highest scores (31.9±12.6) on emotional exhaustion,while the lowest scores (28.1±8.0) on personal accomplishment. According to the results of orderly classification Logistic regression analysis, age, job type,professional qualifications and clinical departments type entered the regression model.

CONCLUSION

Physical resources and emotional resources of medical personnel are overdraft so that they got some high degree of job burnout.Much more attention should be paid to professional mental health of nurses,and personnel who at low age,got low professional titles.Positive measures should be provided, including management mechanism,organizational culture, occupational protection and psychological intervention.

[The preparation and evaluation of the quality control materials for detection of platelet membrane glycoproteins by flow cytometry]

Objective: To prepare the quality control material for detection of platelet membrane glycoproteins by flowcytometry and evaluate the appearance traits, homogeneity and stability of it. Methods: Fresh platelets from the blood group O donors were fixed by the certain concentration of aldehyde solution and then washed by the imidazole buffer. After that, adding certain concentration of lyophilized protection solution into the preparations. The preparations were dispensed to be lyophilized and then were kept refrigerated in 2-8 ℃.According to the protocol of control of lyophilized biological products, the quality indicator for monitoring the prepared process, containing the appearance traits, the residual water, the platelet recovery and the rehydration quality were evaluated. The homogeneity and stability of these preparations were evaluated according to the CNAS-GL03 Guidance on evaluating the homogeneity and stability of samples used for proficiency testing and the ISO Guide 35 Reference material-general and statistical principles for certification. Results: The appearance traits and the rehydration quality of the quality control materials meeted the requirements, with the residual water distributed between 3.96% to 4.04% and the platelet recovery rate ranged from 68% to 72%.The homogeneity evaluation showed that there was no significant difference among the groups(P>0.05). The stability test indicated that the positive rate of platelet membrane glycoproteins CD42b, CD41 and CD62P of the quality control material was -0.14%, -0.14% and 0.74%, respectively, at 16 weeks after storage. There was no linear trend between the percentage of positive platelets with membrane glycoproteins and time(P>0.05). Conclusions: The quality control material for detection of platelet membrane glycoproteins by flow cytometry prepared by us meets the needs of the appearance traits, the residual water, the rehydration quality, the homogeneity and the longtime stability.It is hopeful to be used as internal quality control of the assay in clinic laboratory, the external quality assessment and proficiency evaluation.

[Late reoperations after repaired Stanford type A aortic dissection]

Objective: To summarize the experience of reoperations on patients who had late complications related to previous aortic surgery for Stanford type A dissection. Methods: From August 2008 to October 2016, 14 patients (10 male and 4 female patients) who underwent previous cardiac surgery for Stanford type A aortic dissection accepted reoperations on the late complications at Department of Thoracic and Cardiovascular Surgery, Nanjing Hospital Affiliated to Nanjing Medical University. The range of age was from 41 to 76 years, the mean age was (57±12) years. In these patients, first time operations were ascending aorta replacement procedure in 3 patients, ascending aorta combined with partial aortic arch replacement in 4 patients, aortic root replacement (Bentall) associated with Marfan syndrome in 3 patients, aortic valve combined with ascending aorta replacement (Wheat) in 1 patient, ascending aorta combined with Sun's procedure in 1 patient, Wheat combined with Sun's procedure in 1 patient, Bentall combined with Sun's procedure in 1 patient. The interval between two operations averaged 0.3 to 10.0 years with a mean of (4.8±3.1) years. The reasons for reoperations included part anastomotic split, aortic valve insufficiency, false aneurysm formation, enlargement of remant aortal and false cavity. The selection of reoperation included anastomotic repair, aortic valve replacement, total arch replacement and Sun's procedure. Results: Of the 14 patients, the cardiopulmonary bypass times were 107 to 409 minutes with a mean of (204±51) minutes, cross clamp times were 60 to 212 minutes with a mean of (108±35) minutes, selective cerebral perfusion times were 16 to 38 minutes with a mean of (21±11) minutes. All patients survived from the operation, one patient died from severe pulmonary infection 50 days after operation. Three patients had postoperative complications, including acute renal failure of 2 patients and pulmonary infection of 1 patient, and these patients were recovered after treatment. Thirteen patients were finally recovered from hospital. The patients were followed up for 16 to 45 months, and no aortic rupture, paraplegia and death were observed in the follow-up. Conclusions: Patients for residual aortic dissection after initial operations on Stanford type A aortic dissection should be attached great importance and always need emergency surgery, but the technique is demanding and risk is great for surgeons and patients, which need enough specification and accurate on aortic operation. More importantly, the Sun's procedure also should be performed on the treatment of residual aortic dissection or distal arch expansion, and obtains the short- and long-term results in the future.

[Clinical features and scalp video electroencephalogram analysis of patients with insular epilepsy]

Objective: To explore the clinical and scalp video electroencephalographic(EEG) characteristics of insula lobe epilepsy identified by intracranial electrode, and to provide some references for early diagnosis and clinical evaluation in patients with insula lobe epilepsy. Methods: A total of 12 patients diagnosed with insula lobe epilepsy identified by intracranial electrode were included from Xuanwu Hospital of Capital Medical University from January 2013 to December 2015.Their clinical and EEG data were analyzed. Results: 91.7% of patients had sensory aura before seizure, and had clear consciousness at onset initial time.Visceral motor and visceral sensation were the most common symptoms, and the epilepsy was always ended with somatic movement.There was no prominent characteristic changes in scalp EEG. Conclusions: Clinical features are important for insula lobe epilepsy diagnosis.When patients present symtoms aforementioned, insula lobe epilepsy should be considered.

[Myoclonus and it's associated factors in Creutzfeldt-Jakob disease]

Objective: To analyze features and the related factors of myoclonus of 47 patients with probable or possible Creutzfeldt-Jakob disease (CJD). Methods: All patients diagnosed with"suspected CJD" and hospitalized in Xuanwu Hospital from January 2013 to November 2015 were included, and their clinical information and myoclonus features were analyzed. Age, clinical, course and manifestation, EEG, MRI, CSF14-3-3 features between myoclonus positive group and negative group were compared, and the correlation between myoclonus features and these factors was analyzed using Spearman correlation analyses. Results: (1) Occurrence rate of extrapyramidal symptoms (P=0.028), visual impairment (P=0.025) and dyssomnia (P=0.004) were higher in myoclonus positive group, the differences were significant. Spearman correlation analysis showed that myoclonus was related to extrapyramidal symptoms (P=0.024), visual impairment (P=0.030) and dyssomnia (P=0.001). (2) EEG features showed no significant difference between myoclonus positive and negative group. The 17 myoclonus positive patients were divided into three subgroups, typical EEG change group 52.94%(9/17), atypical EEG change group 23.53%(4/17) and no EEG change group 23.53%(4/17). Difference of myoclonus and other clinical manifestations were not significant among the three subgroups(P>0.05); correlation analysis also found no statistically significant correlation between myoclonus and EEG (P=0.201). Conclusions: Myoclonus often occurs after the damage of locomotor system (including pyramidal tract, extracorticospinal tract and cerebellum) among CJD patients, and it is related to extrapyramidal symptoms , visual impairment and dyssomnia . There is undefined correlation between myoclonus and periodic sharp wave complexes (PSWC) in EEG.

[Feature of magnetic resonance imaging in patients with Creutzfeldt-Jakob disease]

Objective: To assess the imaging features of 43 patients diagnosed as clinically possible or probable Creutzfeldt-Jakob disease (CJD) for providing referential information and experience on applications of MRI in the clinical diagnosis and treatment of CJD. Method: All patients who were diagnosed with "suspected CJD" and hospitalized in Xuanwu Hospital from January 2013 to November 2015 were collected, and their clinical information and MRI imaging features were analyzed retrospectively. Results: Totally 62 patients with "suspected CJD" were rectruited in this study, and 43 of them were diagnosied as probable and possible CJD when they were discharged.The typical MRI feature of CJD patients was "cortical ribbon" sign in MR DWI sequences and/or high signal in cortex or bilateral basal ganglia.In all patients, the simple coritcal involvement was the highest(76.47%, 26/34), followed by the cortical cortex and basal ganglia(23.53%, 8/34). MRI positive group had more prominent extrapyramidal symptoms than MRI negative group (26/31 vs 9/12, P=0.015), but no statistical difference in clinic feature was found between the group with simple cortex affected and the group with both cortex and bilateral basal ganglia affected (P>0.05). Conclusions: MRI images of patients with CJD have special characteristics and have corresponding changes when the patients are in different stages of disease. In combination with the clinical evaluation of disease progression, brain microscopic pathological changes of CJD patients can be assessed by regularly brain MRI examination.

Role of OCT2 and MATE1 in renal disposition and toxicity of nitidine chloride

BACKGROUND AND PURPOSE

Nitidine chloride (NC), a benzophenanthridine alkaloid, has various biological properties including anticancer and analgesic activities. The aim of the present study was to evaluate the role of organic cation transporter 2 (OCT2) and multidrug and toxin extrusion 1 (MATE1) in the renal disposition and nephrotoxicity of NC.

EXPERIMENTAL APPROACH

MDCK cells stably expressing human OCT2 and/or hMATE1 were used to investigate the OCT2- and MATE1-mediated transport of NC. In addition, the accumulation of NC and its potential toxicity were studied in rat primary-cultured proximal tubular (rPCPT) cells and in rats in vivo.

KEY RESULTS

NC was found to be a high-affinity substrate of both OCT2 and MATE1 with high cytotoxicity in MDCK-hOCT2/hMATE1 and MDCK-hOCT2 compared to mock cells. The OCT2 inhibitors, cimetidine and (+)-tetrahydropalmatine ((+)-THP), significantly reduced NC accumulation and cytotoxicity in MDCK-hOCT2, MDCK-hOCT2/hMATE1 and rPCPT cells. Severe kidney damage with high levels of blood urea nitrogen and lactate dehydrogenase (LDH), reduced levels of alkaline phosphatase (ALP) and pathological changes were found in rats after 20 days of successive i.v. doses of NC (5 mg·kg(-1) ·day(-1) ). Concomitantly, the concentration of NC in the kidney reached similar high levels at 2 h after the last dose of the 20 day treatment as those observed at 0.5 h after a single i.v. dose of 5 mg·kg(-1) .

CONCLUSIONS AND IMPLICATIONS

Our data indicate that NC-induced nephrotoxicity might be mainly attributed to OCT2-mediated extensive renal uptake and weak tubular secretion by MATE1.

Development of live attenuated Streptococcus agalactiae vaccine for tilapia via continuous passage in vitro

Fish Streptococcus agalactiae (S. agalactiae) seriously harms the world's aquaculture industry and causes huge economic losses. This study aimed to develop a potential live attenuated vaccine of S. agalactiae. Pre-screened vaccine candidate strain S. agalactiae HN016 was used as starting material to generate an attenuated strain S. agalactiae YM001 by continuous passage in vitro. The biological characteristics, virulence, and stability of YM001 were detected, and the protective efficacy of YM001 immunization in tilapia was also determined. Our results indicated that the growth, staining, characteristics of pulsed-field gel electrophoresis (PFGE) genotype, and virulence of YM001 were changed significantly as compared to the parental strain HN016. High doses of YM001 by intraperitoneal (IP) injection (1.0 × 10(9) CFU/fish) and oral gavage (1.0 × 10(10) CFU/fish) respectively did not cause any mortality and morbidity in tilapia. The relative percent survivals (RPSs) of fishes immunized with YM001 (1.0 × 10(8) CFU/fish, one time) via injection, immersion, and oral administration were 96.88, 67.22, and 71.81%, respectively, at 15 days, and 93.61, 60.56, and 53.16%, respectively, at 30 days. In all tests with 1-3 times of immunization in tilapia, the dosages at 1 × 10(8) and 1 × 10(9) CFU/fish displayed the similar best results, whereas the immunoprotection of the dosages at 1 × 10(6) and 1 × 10(7) CFU/fish declined significantly (P < 0.01), and 1 × 10(5) CFU/fish hardly displayed any protective effect. In addition, the efficacy of 2-3 times of immunization was significantly higher than that of single immunization (P < 0.01) while no significant difference in the efficacy between twice and thrice of immunization was seen (P > 0.05). The level of protective antibody elicited by oral immunization was significantly higher compared to that of the control group (P < 0.01), and the antibody reached their maximum levels 14-21 days after the immunization but decreased significantly after 28 days of vaccination. YM001 bacteria were isolated from the brain, liver, kidney, and spleen tissues of fish after oral immunization and the bacteria existed for the longest time in the spleen (up to 15 days). Taken together, this study obtained a safe, stable, and highly immunogenic attenuated S. agalactiae strain YM001; oral immunization of tilapia with this strain produced a good immune protection.

Syntheses and luminescent properties of a copolymer of terbium-p-aminobenzoic acid-methacrylic acid and styrene

A reactive Tb(III) complex with p-aminobenzoic acid (p-ABA) and methacrylic acid (MAA) as ligands was synthesized. A novel copolymer was synthesized by free radical copolymerization of styrene and the reactive Tb(III) complex in dimethyl sulfoxide (DMSO) with 2,2'-azobis(2-methylpropionitrile) (AIBN) as the initiator. IR and UV/Vis spectra indicate that the copolymer exhibited absorption from polystyrene and the complex. Thermogravimetric analysis indicates that the copolymer remained stable up to 357°C and the thermal stability was significantly improved in comparison with polymer matrix and the Tb(III) complex. The luminescent intensity of the synthetic terbium macromolecular complexes increased with increasing complex monomer content. Moreover, concentration quenching was not observed.

A viscoelastic poromechanical model of the knee joint in large compression

The elastic response of the knee joint in various loading and pathological conditions has been investigated using anatomically accurate geometry. However, it is still challenging to predict the poromechanical response of the knee in realistic loading conditions. In the present study, a viscoelastic, poromechanical model of the knee joint was developed for soft tissues undergoing large deformation. Cartilages and menisci were modeled as fibril-reinforced porous materials and ligaments were considered as fibril-reinforced hyperelastic solids. Quasi-linear viscoelasticty was formulated for the collagen network of these tissues and nearly incompressible Neo-Hookean hyperelasticity was used for the non-fibrillar matrix. The constitutive model was coded with a user defined FORTRAN subroutine, in order to use ABAQUS for the finite element analysis. Creep and stress relaxation were investigated with large compression of the knee in full extension. The contact pressure distributions were found similar in creep and stress relaxation. However, the load transfer in the joint was completely different in these two loading scenarios. During creep, the contact pressure between cartilages decreased but the pressure between cartilage and meniscus increased with time. This led to a gradual transfer of some loading from the central part of cartilages to menisci. During stress relaxation, however, both contact pressures decreased monotonically.

Combined effects of TGFB1 +869 T/C and +915 G/C polymorphisms on acute rejection risk in solid organ transplant recipients: a systematic review and meta-analysis

Background

Transforming growth factor-beta 1(TGF-β1) is involved in the development of acute rejection (AR) episodes in solid organ transplant recipients; and a number of studies have been conducted to investigate the combined effects of human TGF-β1 gene (TGFB1) +869 T/C and +915 G/C polymorphisms on AR risk. However, the results obtained are inconclusive.

Methods

Eligible studies that investigated the haplotypic association between TGFB1 +869 T/C and +915 G/C polymorphisms and AR risk were comprehensively searched in the PUBMED, EMBASE, China National Knowledge Infrastructure, and Wanfang Database. Statistical analyses were performed by using STATA 12.0 and Review Manager 5.0.

Results

Fourteen eligible studies with 565 AR cases and 1219 non-AR cases were included. Overall, a significantly decreased risk was detected in patients carried with intermediate producer (IP) haplotypes (T/C G/C, T/T G/C, and C/C G/G) and/or low producer (LP) haplotypes (C/C G/C, C/C C/C, T/T C/C, and T/C C/C) compared with high producer (HP) haplotypes (T/T G/G and T/C G/G; IP vs. HP: OR = 0.75, 95% CI, 0.58–0.96, P _{heterogeneity}  = 0.238; IP/LP vs. HP: OR  = 0.77, 95% CI, 0.61–0.98, P _{heterogeneity}  = 0.144). In addition, subgroup analysis by transplant types demonstrated a similar association in patients receiving heart transplant (IP vs. HP: OR  = 0.32, 95% CI, 0.14–0.73, P _{heterogeneity}  = 0.790; IP/LP vs. HP: OR  = 0.41, 95% CI, 0.20–0.85, P _{heterogeneity}  = 0.320).

Conclusions

The current meta-analysis and systematic review indicated that recipient TGFB1 HP haplotypes were significantly associated with an increased risk for AR in solid organ transplant recipients, particularly patients receiving cardiac allograft.

Association between transforming growth factor beta-1 +869T/C polymorphism and acute rejection of solid organ allograft: A meta-analysis and systematic review

BACKGROUND

Transforming growth factor beta-1(TGFB1) is involved in the acute rejection (AR) episodes of solid organ transplant recipients. However, results from published studies on the association between donor/recipient TGFB1 +869T/C polymorphism and AR risk are conflicting and inconclusive.

METHODS

PUBMED, EMBASE, CNKI and Wanfang Database were searched to identify eligible studies investigating the association between donor/recipient TGFB1 +869T/C polymorphism and AR risk. Statistical analysis was performed by using STATA 10.0.

RESULTS

A total of 29 studies were included. Overall, the donor TGFB1 +869T/C polymorphism was significantly associated with AR risk in heterozygote comparison (CT vs. TT: OR = 1.67, 95%CI, 1.17-2.39; P heterogeneity=0.285) and dominant model (CC vs.

TC/TT

OR = 1.47, 95%CI, 1.05-2.06; P heterogeneity=0.445). In addition, subgroup analysis revealed that CT variant (CT vs. TT: OR = 1.97, 95%CI, 1.20-3.25; P heterogeneity = 0.777) and CC/CT genotype (CC/CT vs. TT: OR = 1.72, 95%CI, 1.07, 2.78; P heterogeneity = 0.619) within donors contributed to higher risk of AR in recipients administrated with CsA or FK506, compared with those applied only CsA. On the other hand, no significant association between recipient TGFB1 +869T/C polymorphism and AR was detected in all genetic models.

CONCLUSIONS

This meta-analysis and systematic review suggested that donor TGFB1 +869T/C polymorphism was significantly associated with AR of solid organ transplant recipients, and especially among patients in CsA/FK 506 group compared with those in CsA group.

Influences of the depth-dependent material inhomogeneity of articular cartilage on the fluid pressurization in the human knee

The material properties of articular cartilage are depth-dependent, i.e. they differ in the superficial, middle and deep zones. The role of this depth-dependent material inhomogeneity in the poromechanical response of the knee joint has not been investigated with patient-specific joint modeling. In the present study, the depth-dependent and site-specific material properties were incorporated in an anatomically accurate knee model that consisted of the distal femur, femoral cartilage, menisci, tibial cartilage and proximal tibia. The collagen fibers, proteoglycan matrix and fluid in articular cartilage and menisci were considered as distinct constituents. The fluid pressurization in the knee was determined with finite element analysis. The results demonstrated the influences of the depth-dependent inhomogeneity on the fluid pressurization, compressive stress, first principal stress and strain along the tissue depth. The depth-dependent inhomogeneity enhanced the fluid support to loading in the superficial zone by raising the fluid pressure and lowering the compressive effective stress at the same time. The depth-dependence also reduced the tensile stress and strain at the cartilage-bone interface. The present 3D modeling revealed a complex fluid pressurization and 3D stresses that depended on the mechanical contact and relaxation time, which could not be predicted by existing 2D models from the literature. The greatest fluid pressure was observed in the medial condyle, regardless of the depth-dependent inhomogeneity. The results indicated the roles of the tissue inhomogeneity in reducing deep tissue fractures, protecting the superficial tissue from excessive compressive stress and improving the lubrication in the joint.

Interspecies difference of luteolin and apigenin after oral administration of Chrysanthemum morifolium extract and prediction of human pharmacokinetics

The aims of the present study were to study the interspecies difference in the pharmacokinetics of luteolin and apigenin occurring in Chrysanthemum morifolium extract (CME) among rats, beagle dogs, mini-pigs, and humans, and compared the human pharmacokinetic parameters with the data predicted from the above three animals. The plasma concentrations of luteolin and apigenin were determined with a RP-HPLC method. An interspecies difference of pharmacokinetics was found, especially between rats and other species, the plasma concentration of luteolin was much lower than that of apigenin in rats, although the content of luteolin in CME was higherthan that of apigenin, whereas the plasma concentration of luteolin was much higher than that of apigenin in dogs, mini-pigs and humans. Animal scale-up of some pharmacokinetic parameters of luteolin and apigenin were also performed after rats, beagle dogs, mini-pigs and humans were orally given CME at dosages of 400 mg/kg, 102 mg/kg, 90 mg/kg, and 20 mg/kg, respectively. Linear relationships were obtained between log mean retention time (MRT) and log species body weight (W) (kg), and log elimination half-life (t1/2) (h) and logW. The corresponding allometric equations were MRT=9.382W(0.1711) (R2 = 0.9999) and t1/2 = 4.811W(0.1093) (R2 = 0.9013) for luteolin, MRT = 12.53W(0.0356) (R2 = 0.9980) and t1/2 = 7.940W(0.0294) (R2 = 0.9258) for apigenin, respectively. The predicted human pharmacokinetic parameters (MRT and t1/2) by an allometric approach were 18.6 h and 7.46 h for luteolin, 14.3 h and 8.95 h for apigenin, respectively, which were close to the values obtained from humans (20 mg CME/kg) in the present study. The study has demonstrated the possibility to extrapolate the pharmacokinetic behavior of flavonoids from animals to humans.

Reconsideration on the use of elastic models to predict the instantaneous load response of the knee joint

Fluid pressurization in articular cartilages and menisci plays an important role in the mechanical function of the knee joint. However, fluid pressure has not been incorporated in previous finite element modelling of the knee, instead elastic models of the knee are widely used. It is believed that an elastic model can be used to predict the instantaneous load response of the knee as long as large effective moduli for the cartilaginous tissues are used. In the present study, the instantaneous response of the knee was obtained from a proposed model including fluid pressure and fibril reinforcement in the cartilaginous tissues. The results were then compared with those obtained from an elastic model using the effective modulus method. It was found that the deformations and contact pressures predicted by the two models were substantially different. An unconfined compression of a tissue disc was used to help understand the issue. It was clear that a full equivalence between the instantaneous and elastic responses could not be established even for this simple case. A partial equivalence in stress could be conditionally established for a given unconfined compression, but it was not valid for a different magnitude of compression. The instantaneous deformation of the intact tissues in the joint was even more difficult to determine using the effective modulus method. The results thus obtained were further compromised because of the uncertainty over the choice of effective modulus. The tissue non-linearity was one of the factors that made it difficult to establish the equivalence in stress. The pressurized tissue behaved differently from a solid material when non-linear fibril reinforcement was presented. The direct prediction of the instantaneous response using the proposed poromechanical model had the advantage of determining the fluid pressure and incompressible deformation.

Creep behavior of the intact and meniscectomy knee joints

The mechanical functions of the menisci may be partially performed through the fluid pressurization in articular cartilages and menisci. This creep behavior has not been investigated in whole knee joint modeling. A three-dimensional finite element knee model was employed in the present study to explore the fluid-flow dependent creep behaviors of normal and meniscectomy knees. The model included distal femur, tibia, fibula, articular cartilages, menisci and four major ligaments. Articular cartilage or meniscus was modeled as a fluid-saturated solid matrix reinforced by a nonlinear orthotropic and site-specific collagen network. A 300 N compressive force, equal to half of body weight, was applied to the knee in full extension followed by creep. The results showed that the fluid pressurization played a substantial role in joint contact mechanics. Menisci bore more loading as creep developed, leading to decreased stresses in cartilages. The removal of menisci not only changed the stresses in the cartilages, which was in agreement with published studies, but also altered the distribution and the rate of dissipation of fluid pressure in the cartilages. The high fluid pressures in the femoral cartilage moved from anterior to more central regions of the condyles after total meniscectomy. For both intact and meniscectomy joints, the fluid pressure level remained considerably high for thousands of seconds during creep, which lasted even longer after meniscectomy. For the femoral cartilage, the maximum principal stress was generally in agreement with the fiber direction, which indicated the essential role of fibers in load support of the tissue.

A human knee joint model considering fluid pressure and fiber orientation in cartilages and menisci

Articular cartilages and menisci are generally considered to be elastic in the published human knee models, and thus the fluid-flow dependent response of the knee has not been explored using finite element analysis. In the present study, the fluid pressure and site-specific collagen fiber orientation in the cartilages and menisci were implemented into a finite element model of the knee using fibril-reinforced modeling previously proposed for articular cartilage. The geometry of the knee was obtained from magnetic resonance imaging of a healthy young male. The bones were considered to be elastic due to their greater stiffness compared to that of the cartilages and menisci. The displacements obtained for fast ramp compression were essentially same as those for instantaneous compression of equal magnitude with the fluid being trapped in the tissues, which was expected. However, a clearly different pattern of displacements was predicted by an elastic model using a greater Young's modulus and a Poisson's ratio for nearly incompressible material. The results indicated the influence of fluid pressure and fiber orientation on the deformation of articular cartilage in the knee. The fluid pressurization in the femoral cartilage was somehow affected by the site-specific fiber directions. The peak fluid pressure in the femoral condyles was reduced by three quarters when no fibril reinforcement was assumed. The present study indicates the necessity of implementing the fluid pressure and anisotropic fibril reinforcement in articular cartilage for a more accurate understanding of the mechanics of the knee.

Pharmacokinetics of dl-praeruptorin A after single-dose intravenous administration to rats with liver cirrhosis

BACKGROUND AND THE PURPOSE OF THE STUDY

As a novel drug in the treatment of cardiac diseases, dl-praeruptorin A (Pd-Ia) is the major active component of traditional herbal medicine Peucedanum praeruptorum Dunn and is metabolized primarily via cytochrome P450 isozymes (CYP) 3A1 and 3A2 in rats. In the present study, the influence of liver cirrhosis on pharmacokinetics of Pd-Ia and hepatic mRNA expression of CYP3A1 and 3A2 in rats with experimental liver cirrhosis (LC rats) were evaluated.

METHODS

Pd-Ia was given intravenously (5 mg kg(-1)) to LC rats induced by dimethylnitrosamine and pharmacokinetic variables were measured. Enzyme kinetic metabolism of Pd-Ia in rat hepatic microsomes was also investigated and hepatic mRNA expression of CYP3A1 and 3A2 were measured by real-time PCR.

RESULTS AND MAJOR CONCLUSION

After intravenous administration in LC rats, the area under the plasma concentration-time curve from time zero to infinity (AUC0-8) was significantly greater than that in control rats, which might be due to slower rate of the hepatic blood flow and significant slower hepatic intrinsic clearance (CL(int)) in rats. The decreased metabolic clearance of Pd-Ia in LC rats might be at least partly caused by the decreased levels of CYP3A1 and 3A2 responsible for Pd-Ia metabolism. These findings may provide new insights into the inter- and intra-individual pharmacokinetic variability of Pd-Ia.

University-based peer health education in China: the Shantou experience

OBJECTIVE

University-based peer health education is a recent development in China. The authors evaluated a newly implemented program in the Guangdong province.

PARTICIPANTS AND METHODS

In September 2006, the authors conducted a cross-sectional study using self-administered questionnaires on 30 peer educators and 247 students.

RESULTS

All peer educators and the majority of student respondents positively evaluated the program. Although students preferred to seek health information online, approximately one-quarter of the student respondents would contact peer educators. Third-year students were more than twice as likely (29.1%) to contact peer educators than were fourth-year students (13.1%). The peer educators perceived diet, physical activity, safer sex, and mental health as the most relevant student health topics. Peer educators cited acquiring factual information and medical skills, rather than personal development, as the most important things learned from the program.

CONCLUSIONS

Despite some promising results, Western-based peer education models may require cultural adaptation for greater effectiveness in China.

Fluid pressure driven fibril reinforcement in creep and relaxation tests of articular cartilage

Biological tissues exhibit diverse mechanical behaviors because of complex material properties. As has been shown for ligaments and intervertebral discs, mathematical models often appear to well predict load responses individually by adjusting model parameters, but likely fail to describe several different load responses simultaneously using the same model parameters. In the present study, we attempted to describe and explain both creep and relaxation responses of articular cartilage using a fibril-reinforced model, which has been successfully used to account for the load response of the relaxation tests of articular cartilage. Experiments were performed on bovine articular cartilage disks (n=8) using multi-step loading protocols, involving both creep and relaxation in each protocol. The experimental results indicated that mechanical changes, such as fiber recruitment in collagen network during stretch, recovered fully upon unloading. Creep loading did not affect relaxation properties, and vice versa. Relaxation proceeded much faster than creep, because of different fluid pressure profiles. The load sharing among the proteoglycan matrix, collagen network and fluid pressurization was predicted to differ for the creep and relaxation testing. The experimentally observed strong creep and relaxation responses in unconfined compression could not be predicted if either fibril reinforcement or fluid pressurization were neglected. It was essential to consider the interplay between nonlinear fibril reinforcement and fluid pressurization for the transient response (this interplay may be best termed as fluid pressure driven fibril reinforcement). Fibril reinforcement played a relatively insignificant role in the compressive load response at equilibrium, in agreement with previous findings for cartilage stress relaxation testing.

Prediction of recovery from a post-traumatic coma state by diffusion-weighted imaging (DWI) in patients with diffuse axonal injury

INTRODUCTION

To determine whether diffusion-weighted magnetic resonance (MR) imaging findings combined with initial clinical factors indicate the depth of shearing lesions in the brain structure and therefore relate to coma duration in diffuse axonal injury (DAI).

METHODS

A total of 74 adult patients (48 male and 26 female) with DAI were examined with conventional MR imaging and diffusion-weighted MR imaging between 2 hours and 20 days after injury. Apparent diffusion coefficient (ADC) maps were obtained and the mean ADC values of each region of interest (ROI) were measured using MRI console software. The involvement of the brainstem, deep gray matter, and corpus callosum was determined for each sequence separately as well as for the combination of all sequences. The correlations between MR imaging findings indicating the presence of apparent brain injury combined with initial clinical factors were determined.

RESULTS

Clinical characteristics, such as initial score on the Glasgow coma scale (GCS), age and number of all lesions, and ADC scores were predictive of the duration of coma.

CONCLUSION

It was possible to predict post-traumatic coma duration in DAI from cerebral MR imaging findings combined with clinical prognostic factors in the acute to subacute stage after head injury. Age, ADC scores, GCS score and number of lesions were highly significant in predicting coma duration. The technique presented here might provide a tool for in vivo detection of DAI to allow the prediction of the coma duration during the early stages in patients with traumatic brain injury.

Arthroscopic evaluation of cartilage degeneration using indentation testing--influence of indenter geometry

BACKGROUND

It has been suggested that the early onset of cartilage degeneration might be detected with a handheld indentation probe during knee arthroscopy, prior to any visible change on the articular surface. Collagen degradation has been considered as the first sign of cartilage degeneration. Therefore, it is important to consider the collagen network as a distinct constituent in the study of arthroscopic evaluation of cartilage degeneration.

METHODS

The tip of an arthroscopic probe (indenter) was modeled as rigid and in contact with a cartilage/bone disk of sufficiently large radius to simulate an indentation in a joint. A fibril-reinforced model of cartilage, including streaming potentials and distinct constitutive laws for the proteoglycan matrix and collagen network, was used to determine the contact mechanics of indenter and cartilage. The finite element package ABAQUS was employed to obtain numerical solutions.

FINDINGS

A spherical indenter produces a relatively uniform deformation in cartilage, but can easily slide on the articular surface. In contrast, a cylindrical indenter produces great deformation gradients for quick compression rates, but does not slide as easily on the articular surface as the spherical indenter. Small porous and large solid indenters should be used to evaluate the properties of the proteoglycan matrix and collagen network, respectively, in order to minimize or maximize the fluid pressure in the corresponding case. When the collagen network is substantially degraded, the gradients of fluid pressure and deformation are greatly reduced regardless of indenter geometry.

INTERPRETATION

The indenter geometry including its porosity is important to the material safety of articular cartilage in indentation and precise evaluation of cartilage degeneration.

Evaluation of intra-renal oxygenation during water diuresis: a time-resolved study using BOLD MRI

Hypoxia of the renal medulla is a possible precursor to the onset of acute renal failure in humans and therefore an understanding of the factors influencing the oxygenation status within the renal medulla is very important. Blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) has been shown to non-invasively evaluate intra-renal oxygenation levels of the renal medulla in humans. A newly implemented three-dimensional (3-D) multiple gradient-recalled echo sequence, which permits examination of temporal responses to physiological or pharmacological stimuli, was used to monitor changes in intra-renal oxygenation status during water diuresis. Five healthy, young subjects (22+/-1.2 years) took part in the study. BOLD MRI data were acquired before and after water loading. Studies were repeated on a separate day after the subjects were pretreated with naproxen. Water diuresis significantly improved renal medullary oxygenation levels in all subjects (pre-waterload=30.3 1/s vs post-waterload 22.8 1/s); however, the temporal response was found to be subject dependent. In the presence of cyclooxygenase (COX) inhibition by naproxen, the improvement in oxygenation during water diuresis was completely abolished (pre-waterload=27.5 1/s vs post-waterload 28.5 1/s). Monitoring of temporal responses for the first time during water loading allowed for an appreciation of subject dependence. Comparison of the temporal response in terms of slopes demonstrated a significant difference between the waterload studies with and without naproxen (with naproxen=0.056 1/(s min) vs without naproxen=0.25 1/(s min)). The observed effects of naproxen were consistent with previous findings with COX inhibition.

Electromechanical response of articular cartilage in indentation--considerations on the determination of cartilage properties during arthroscopy

A finite element formulation of streaming potentials in articular cartilage was incorporated into a fibril-reinforced model using the commercial software ABAQUS. This model was subsequently used to simulate interactions between an arthroscopic probe and articular cartilage in a knee joint. Fibril reinforcement was found to account for large fluid pressure at considerable strain rates, as has been observed in un-confined compression. Furthermore, specific electromechanical responses were associated with specific changes in tissue properties that occur with cartilage degeneration. For example, the strong strain-rate dependence of the load response was only observed when the collagen network was intact. Therefore, it is possible to use data measured during arthroscopy to evaluate the degree of cartilage degeneration and the source causing changed properties. However, practical problems, such as the difficulty of controlling the speed of the hand-held probe, may greatly reduce the reliability of such evaluations. The fibril-reinforced electromechanical model revealed that high-speed transient responses were associated with the collagen network, and equilibrium response was primarily determined by proteoglycan matrix. The results presented here may be useful in the application of arthroscopic tools for evaluating cartilage degeneration, for the proper interpretation of data, and for the optimization of data collection during arthroscopy.

The role of viscoelasticity of collagen fibers in articular cartilage: axial tension versus compression

The role of viscoelasticity of collagen fibers in bovine articular cartilage was examined in compression and tension using stress relaxation measurements in the axial direction (normal to the articular surface). Experimentally, for a given axial strain, both peak and equilibrium loads were higher in tension than in compression, whereas stress relaxation was stronger in compression, as indicated by the higher peak-to-equilibrium ratios. A viscoelastic fibril-reinforced model including fluid flow was used for analysis of the experimental data. The collagen fibrillar matrix was assumed to be viscoelastic with a strain-dependent tensile modulus, and the nonfibrillar matrix was modeled as linearly elastic. For axial tension, collagen viscoelasticity was found to account for most of the stress relaxation, while the effects of fluid pressurization on the tensile stress were negligible. In contrast, for axial compression, the dominant mechanism for stress relaxation arose from fluid pressurization, while the associated relaxation in collagen fibers mainly resulted in an increase in radial strain. The effective Poisson's ratio, defined as the ratio of the radial and axial strains, was generally smaller in compression than in tension, and deviated from the true Poisson's ratio in tensile tests because of the frictional contacts between the specimen and the loading platens. Furthermore, lower collagen elasticity in the axial direction was observed than in the radial direction. This study illustrates the essential role of collagen viscoelasticity and interstitial fluid pressurization in the mechanical response of articular cartilage.