Objective:To investigate whether chitosan-polyelectrolyte complex (CS-PEC) can be used as scaffold for chondrocyte culture and for cartilage regeneration in vivo.Methods:Condylar chondrocytes of fetal mouse were seeded onto the three-dimension gel scaffolds of CS-PEC and cultured.The cultured chondrocytes/CS-PEC complex samples were transplanted subcutaneously into nude mice and the CS-PEC scaffold without chondrocyte was used as the control.The animals were sacrificed 4 and 8 weeks after operation respectively.Cartilage formulation was observed by histological and immunohistochemical methods.Results:In the in vitro culture the majority of cells attached to the CS-PEC surface and expanded rapidly. 4 weeks after transplantation,in the chondrocytes/CS-PEC complex the scaffold maintained mostly the original structure. Hypertrophic chondrocytes appeared in scaffold materials. CollagenⅡwas positive in the new cartilage. 8 weeks after transplantation the scaffold degraded almost completely and new cartilage could be observed. CollagenⅡ and cartilage matrix was positive in the new cartilage and the collagen I was positive in the surrounding fibroblast-like cells. In control transplants,8 week after transplantation some fibre-like tissue formed in the circumference, but there was no new cartilage formation and the collagen II and the cartilage matrix was negative.Conclusions:CS-PEC may be used as scaffold for fibre-cartilage regeneration.

ObjectiveTo study the effects of group BStreptococcus (GBS) colonization in late pregnancies on neonatal GBS infection.MethodsA total of 17 019 pregnant women who received antenatal care and delivered in Xiamen Maternal and Child Care Hospital from June 1, 2014 to May 31, 2015 were enrolled in this study. Secretions from the lower third of the vagina in the pregnant women at 35-37 weeks of gestation or having premature baby(regardless of gestational age) were obtained to test GBS by standard bacterial culture, and 1 472 cases underwent GBS DNA test by real-time fluorescent quantitative-polymerase chain reaction (PCR) meanwhile. The pregnant women colonized with GBS (GBS culture and/or PCR DNA test positive) were given intrapartum antibiotic prophylaxis (IAP) during parturition or rupture of fetal membranes. Detection rate of the two methods was compared, and the effects of GBS colonization and IAP on neonatal GBS infection were analyzed to identify the risk factors of neonatal early-onset GBS disease (GBS-EOD). Two independent samplest-test,Chi-square test and Logistic regression analysis were used for statistical analysis. ResultsThe detection rate of GBS culture and PCR DNA test was 14.43% (2 456/17 019) and 14.13%(288/1 472), respectively. The total colonization rate was 14.52%(2 472/17 019). Based on the culture results as golden criteria, the sensitivity, specificity, positive predictive value and negative predictive value of PCR assay were 95.05%, 98.74%, 92.31% and 99.21%, respectively. There were 17 332 deliveries from the 17 019 pregnant women, of which 31 cases had GBS-EOD. The incidence of neonatal GBS-EOD in maternal GBS colonization [1.05%(26/2 472)] was 31 times higher than in pregnant women without GBS colonization [0.34‰(5/14 547)]. Among the 31 infants with GBS-EOD, 24 had pneumonia, five had sepsis, and two had meningitis. The case fatality rate was 6.45%(2/31). Logistic regression analysis found that chorioamnionitis was an independent risk factor of neonatal GBS-EOD (OR=40.425, 95%CI: 7.514-379.782,P=0.000). Compared with the non-IAP group,IAP group had a lower incidence of GBS-EOD among the pregnant women colonized with GBS [0.94%(23/2 443) vs 10.34%(3/29),χ2=24.350,P<0.01].ConclusionsGBS colonization in late pregnant women has adverse effects. Therefore, routine maternal rectovaginal culture of GBS may be necessary and IAP should be applied in those with GBS colonization.

Objective: To evaluate the effect of exogenous insulin on endoplasmic reticulum stress in myocardial tissues during insulin resistance in the rabbits undergoing cardiopulmonary bypass (CPB). Methods: Forty healthy adult New Zealand white rabbits of both sexes, weighing 2.5-3.0 kg, were divided into 4 groups (n=10 each) using a random number table method: control group (group C), CPB group, CPB plus insulin group (group I) and CPB plus normal saline group (group NS). Group C received no treatment.An insulin resistance model was established in group CPB.Insulin was continuously infused (the infusion rate was adjusted according to the blood glucose) starting from establishing CPB to 1 day after operation in group I. The equal volume of normal saline was given starting from establishing CPB to 1 day after operation in group NS.Blood samples were collected from the left femoral artery, and myocardial tissues obtained before CPB (T₁) and at 15, 30 and 60 min after aortic opening (T_2-4). The level of blood glucose was determined using oxidase method, the level of glucagon was detected by the radioimmunoassay method, and the insulin resistance index was calculated.The expression of inositol-requiring protein-1α(IRE1α), XBP1 and caspase-12 was measured by Western blot.The expression of IRE1α, XBP1 and caspase-12 mRNA was measured by fluorescent quantitative real-time polymerase chain reaction.Cell apoptosis was detected by TUNEL. Results: Compared with group C, blood glucose and glucagon levels at T_2-4 and insulin resistance index at T₄ were significantly increased, and the expression of inositol-requiring protein-1α(IRE1α), XBP1 and caspase-12 protein and mRNA was up-regulated at T₄ in CPB, I and NS groups (P<0.05). Compared with group CPB, blood glucose and glucagon levels at T_2-4 and insulin resistance index at T₄ were significantly decreased, and the expression of IRE1α, XBP1 and caspase-12 protein and mRNA was down-regulated at T₄ in group I (P<0.05). Conclusion Exogenous insulin significantly improves insulin resistance in myocardial tissues, and the mechanism is related to inhibiting endoplasmic reticulum stress and reducing cell apoptosis in the rabbits undergoing CPB.

Objective To construct a nonparametric proportional hazards (PH) model for mixed informative interval-censored failure time data for predicting the risks in heart transplantation surgeries. Methods Based on the complexity of mixed informative interval-censored failure time data, we considered the interdependent relationship between failure time process and observation time process, constructed a nonparametric proportional hazards (PH) model to describe the nonlinear relationship between the risk factors and heart transplant surgery risks and proposed a two-step sieve estimation maximum likelihood algorithm. An estimation equation was established to estimate frailty variables using the observation process model. I-spline and B-spline were used to approximate the unknown baseline hazard function and nonparametric function, respectively, to obtain the working likelihood function in the sieve space. The partial derivative of the model parameters was used to obtain the scoring equation. The maximum likelihood estimation of the parameters was obtained by solving the scoring equation, and a function curve of the impact of risk factors on the risk of heart transplantation surgery was drawn. Results Simulation experiment suggested that the estimated values obtained by the proposed method were consistent and asymptotically effective under various settings with good fitting effects. Analysis of heart transplant surgery data showed that the donor's age had a positive linear relationship with the surgical risk. The impact of the recipient's age at disease onset increased at first and then stabilized, but increased against at an older age. The donor-recipient age difference had a positive linear relationship with the surgical risk of heart transplantation. Conclusion The nonparametric PH model established in this study can be used for predicting the risks in heart transplantation surgery and exploring the functional relationship between the surgery risks and the risk factors.

Objective To construct a nonparametric proportional hazards (PH) model for mixed informative interval-censored failure time data for predicting the risks in heart transplantation surgeries. Methods Based on the complexity of mixed informative interval-censored failure time data, we considered the interdependent relationship between failure time process and observation time process, constructed a nonparametric proportional hazards (PH) model to describe the nonlinear relationship between the risk factors and heart transplant surgery risks and proposed a two-step sieve estimation maximum likelihood algorithm. An estimation equation was established to estimate frailty variables using the observation process model. I-spline and B-spline were used to approximate the unknown baseline hazard function and nonparametric function, respectively, to obtain the working likelihood function in the sieve space. The partial derivative of the model parameters was used to obtain the scoring equation. The maximum likelihood estimation of the parameters was obtained by solving the scoring equation, and a function curve of the impact of risk factors on the risk of heart transplantation surgery was drawn. Results Simulation experiment suggested that the estimated values obtained by the proposed method were consistent and asymptotically effective under various settings with good fitting effects. Analysis of heart transplant surgery data showed that the donor's age had a positive linear relationship with the surgical risk. The impact of the recipient's age at disease onset increased at first and then stabilized, but increased against at an older age. The donor-recipient age difference had a positive linear relationship with the surgical risk of heart transplantation. Conclusion The nonparametric PH model established in this study can be used for predicting the risks in heart transplantation surgery and exploring the functional relationship between the surgery risks and the risk factors.

Objective:To explore the changes in entero-insular axis function and its role in mice with severe burns.Methods:This study was an experimental study. Ninety C57BL/6J male mice aged 8-10 weeks were divided into sham injury group and burn group (with 45 mice in each group) according to the random number table. A full-thickness scald (hereinafter referred to as burn) wound of 30% of the total body surface area was created on the back of mice in burn group, and the mice in sham injury group were simulated to cause a sham injury. Twenty-four hours after injury, the fasting blood glucose was measured ( n=12), followed by intraperitoneal glucose tolerance test and oral glucose tolerance test; the curve of blood glucose concentration changes over time was plotted, and the area under the curve was calculated ( n=6); the blood was taken from the heart before intraperitoneal injection or gavage of glucose solution and at 30, 60, and 120 minutes after intraperitoneal injection or gavage of glucose solution for measuring the plasma insulin and glucagon like peptide-1 (GLP-1) levels using enzyme-linked immunosorbent assay (ELISA), with a sample number of 3; the ileal tissue was taken from 3 mice in each group for detecting the GLP-1 expression and apoptosis levels of intestinal L cells by immunofluorescence staining and TdT-mediated dUTP nick-end labeling staining; the pancreatic islets were collected from 6 mice in each group for glucose-stimulated insulin secretion experiments. After incubation with low glucose (2.8 mmol/L glucose) and high glucose (16.7 mmol/L glucose), the supernatant was taken and the insulin level was detected using ELISA. Thirty-six C57BL/6J male mice aged 8-10 weeks were divided into sham injury group, burn group, and burn+exendin-4 (Ex-4) group (with 12 mice in each group) according to the random number table. The mice in sham injury group and burn group were subjected to the same corresponding treatment as before. The mice in burn+Ex-4 group were injured in the same way as the burn group mice followed by treatment with GLP-1 receptor agonist Ex-4. Twenty-four hours after injury, mouse pancreatic islets were collected, the protein expressions of heavy-chain binding protein (BIP), protein kinase R-like endoplasmic reticulum kinase (PERK), phosphorylated PERK (p-PERK), eukaryotic translation initiation factor 2α (eIF2α), phosphorylated eIF2α (p-eIF2α), and CCAAT/enhancer-binding protein homologous protein (CHOP) were detected using Western blotting, and the p-PERK/PERK and p-eIF2α/eIF2α ratios were calculated ( n=3), the apoptosis rate of pancreatic islet cells was detected using flow cytometry ( n=3), the glucose stimulated insulin secretion experiment was conducted as before to detect insulin levels in the supernatant ( n=6). Results:Twenty-four hours after injury, the fasting blood glucose of mice in burn group was (7.3±1.0) mmol/L, which was significantly higher than (5.1±0.6) mmol/L in sham injury group ( t=6.36, P<0.05). Twenty-four hours after injury, in the intraperitoneal glucose tolerance test and oral glucose tolerance test, the areas under the curve of blood glucose concentration changes over time of mice in burn group were significantly larger than those in sham injury group (with t values of 4.32 and 6.03, respectively, P<0.05); compared with those in sham injury group, the plasma insulin levels of mice before intraperitoneal injection of glucose solution and the plasma GLP-1 levels of mice before intraperitoneal injection or gavage of glucose solution in burn group were significantly decreased ( P<0.05), and the plasma levels of insulin of mice at 30, 60, and 120 minutes after intraperitoneal injection or gavage of glucose solution, as well as the plasma levels of GLP-1 of mice at 30 and 60 minutes after gavage of glucose solution were significantly decreased in burn group ( P<0.05). Twenty-four hours after injury, compared with those in sham injury group, the GLP-1 expression level of intestinal L cells of mice in burn group was significantly decreased ( t=7.74, P<0.05), and the apoptosis level was significantly increased ( t=14.28, P<0.05). Twenty-four hours after injury, the insulin level in the supernatant of mice pancreatic islet incubated with high glucose in burn group was (8.5±0.4) ng/mg, which was significantly lower than (15.7±0.3) ng/mg in sham injury group ( t=18.68, P<0.05). Twenty-four hours after injury, compared with those in sham injury group, the protein expression levels of BIP, p-PERK/PERK, p-eIF2α/eIF2α, and CHOP in the pancreatic islets of mice in burn group were significantly increased ( P<0.05); compared with those in burn group, the protein expression levels of BIP, p-PERK/PERK, p-eIF2α/eIF2α, and CHOP in the pancreatic islets of mice in burn+Ex-4 group were significantly decreased ( P<0.05). Twenty-four hours after injury, the apoptosis rate of pancreatic islet cells of mice in burn group was (32.0±3.0)%, which was significantly higher than (10.3±2.5)% in sham injury group ( P<0.05); the apoptosis rate of pancreatic islet cells of mice in burn+Ex-4 group was (20.0±3.6)%, which was significantly lower than that in burn group ( P<0.05). Twenty-four hours after injury, the insulin level in the supernatant of mice pancreatic islet incubated with high glucose in burn group was significantly lower than that in sham injury group ( P<0.05), while the insulin level in the supernatant of mice pancreatic islet incubated with high glucose in burn+Ex-4 group was significantly higher than that in burn group ( P<0.05). Conclusions:After severe burns, the mice display dysfunction of the entero-insular axis, increased apoptosis of intestinal L cells, decreased synthesis and secretion of GLP-1, endoplasmic reticulum stress and increased apoptosis in pancreatic islet cells and a decrease in glucose-stimulated insulin secretion. The GLP-1 receptor agonist Ex-4 can protect the function of pancreatic islet cells of mice with severe burns, reducing the apoptosis level of pancreatic islet cells and promoting insulin secretion possibly via the alleviation of endoplasmic reticulum stress.