Objective: To establish a method for determining the molecular weight and molecular weight distribution of Poly(Lactide-co-Glycolide Acid) (PLGA) using Size Exclusion Chromatography-Refractive Index-Multiangle Laser Light Scattering (SEC-RI-MALLS) and Size Exclusion Chromatography-Refractive Index (SEC-RID), and to compare the results obtained from these two methods.
Methods: For SEC-RI-MALLS, tetrahydrofuran was used as the mobile phase, Shodex GPC KF-803L was employed as the chromatographic column with a flow rate of 1 mL·min^-1, column temperature at 30 ℃, and an injection volume of 100 μL. For SEC-RID, tetrahydrofuran was also used as the mobile phase, Agilent PLgel 5 μm MIXD-D was used as the chromatographic column with a flow rate of 1 mL·min^-1, column temperature at 30 ℃, differential detector temperature at 35 ℃, and an injection volume of 20 μL. The molecular weight and molecular weight distribution were calculated using Agilent’s GPC software. The newly established methods were validated methodologically, and the molecular weight and molecular weight distribution of 13 batches of samples were determined.
Results: The precision, accuracy, stability, and repeatability tests for SEC-RI-MALLS showed RSD values of 1.35%, 1.58%, 1.53%, and 1.26%, respectively. The SEC-RID method exhibited good linearity (r=0.999 9), with RSD values for precision, accuracy, stability, and repeatability tests (n=6) of 2.05%, 1.62%, 1.30%, and 2.97%, respectively. The results obtained from SEC-RI-MALLS were lower than those from SEC-RID, and the molecular weight distribution coefficient was smaller, but the results from the paired T-test performed with the value measured by SEC-RID method and the value measured by SEC-RI-MALLS method multiplied a conversion coefficient of 1.5 showed no significant difference between the two methods.
Conclusion: Both methods are stable and reliable, and can be used for the determination of PLGA molecular weight and molecular weight distribution based on the specific situations.

Objective:To investigate the effects and mechanisms of curcumin on insulin resistance in streptozocin-induced diabetic rats.Methods:Diabetic rats were induced by intraperitoneal injection of STZ, then all the rats were randomly divided into diabetes (DM), diabetes+ curcumin (DM+ Cur), and diabetes + buffer control (DM+ NC) groups. Normal SD rats were used as control group (NC). The DM+ Cur group was treated with curcumin, while the DM+ NC group was treated with equal-volume buffer. The test lasted 12 weeks. The blood glucose was detected, and hyperinsulinemic-euglycemic clamp test was performed to estimate peripheral insulin resistance. At the end of the experiments, rats were killed and the total protein and cell membrane protein were extracted from skeletal muscle. The levels of phosphorylated PI3K, phosphorylated AKT, total PI3K, and total AKT were measured by Western blot. The levels of total GLUT4 and GLUT4 of cell membrane were also detected by Western blot, GLUT4 levels in skeletal muscle cell membranes were detected by immunofluorescence.Results:Blood glucose levels of DM+ Cur group were lower than those of DM group [(18.67±1.99 vs 24.38±2.88) mmol/L, P<0.05], and insulin resistance was also improved[the average GIR(14.69±0.29 vs 10.25±0.30) mg·kg -1·min -1, P<0.01]. The phosphorylation levels of PI3K and AKT were increased, and GLUT4 translocation to the cell membrane was increased. Conclusion:By activating the PI3K/AKT pathway, curcumin promotes GLUT4 translocation, increases skeletal muscle glucose uptake, and finally improves insulin resistance.

Objective:To investigate the changes of proopiomelanocortin(POMC) expression in hypothalamus and corresponding metabolism in miR-21 knockout mice.Methods:miR-21 knockout or wild-type C57BL/6J mice were divided into diabetic group and control group, respectively. Diabetic mice model were forged with high-fat diet and low-dose streptozotocin. The changes of body weight and blood glucose in each group were monitored. By the end of the experiment, mice were sacrificed, and POMC protein expression and STAT3 mRNA expression in hypothalamus were detected.Results:There were no significant differences in body weight and blood glucose levels among all groups at baseline( P>0.05). The differences of body weight and blood glucose levels among various groups were compared at 3, 6, 9 and 12 weeks after the model was established. The results showed that body weight of mice in the diabetes group or miR-21 knockout+ diabetes group was higher than that in the control group at each time point( P<0.05). Moreover, there were significant difference in body weight between diabetes group and miR-21 knockout+ diabetes group at 3 and 12 weeks( P<0.05). The blood glucose levels in diabetes group were significantly higher than those in other groups at each time point( P<0.05). The blood glucose level in miR-21 knockout+ diabetes group was lower than that in diabetes group and higher than control group( P<0.05). POMC protein and STAT3 mRNA levels in diabetes group were significantly lower than those in control group, while those in the miR-21 knockout+ diabetes group were higher than those in the diabetes group. Conclusions:The expression of POMC in hypothalamus of miR-21 knockout mice is higher than that of wild-type diabetic mice. miR-21 knockout can decrease blood glucose level and body weight, and improve energy metabolism of diabetic mice.

Objective To analyze the correlation between urinary albumin/creatinine ratio (ACR) and 24-hour urinary microalbumin (UMA) and evaluate the predictive value of ARC for early diabetic nephropathy.Methods A total of 368 patients with type 2 diabetes mellitus were retrospectively collected.Early diabetic nephropathy was defined as 24h UMA 30～＜300 mg/24h.The correlation between ACR and 24hUMA,and the area under the receiver operating characteristic (ROC) curve of ACR in diagnosis of early diabetic nephropathy were calculated.Gender,age,course of disease,fasting venous blood glucose,glycosylated hemoglobin,blood pressure,triglyceride and total cholesterol were used as adjusting variables to establish univariate and multivariate logistic models of ACR for early diabetic nephropathy,respectively.A regression model was used to evaluate the diagnostic value of ACR for early diabetic nephropathy.Results The correlation between ACR and 24h UMA was 0.658.The area under ROC curve of ACR for early diabetic nephropathy was 0.907 before and 0.933 after adjustments of gender,age,course of disease,fasting venous blood glucose,glycosylated hemoglobin,blood pressure,triglyceride and total cholesterol,respectively.The OR value of ACR of diabetic nephropathy was 2.016 before and 2.762 after same adjustments.The calibration of Hosmer-Lemeshow chi-square test evaluation model was 19.362 before (P=0.13) and 14.928 after adjustments (P=0.061).Conclusion ACR is a better predictor for early diabetic nephropathy although its value is influenced by gender,age,course of disease,blood sugar,lipid,and blood pressure.

Objective To investigate the application value of biological mesh in the pelvic floor reconstruction of extralevator abdominoperineal excision (ELAPE) for advanced low rectal cancer (RC).Methods The retrospective cohort study was conducted.The clinicopathological data of 228 patients with advanced low RC who underwent ELAPE in the Beijing Chaoyang Hospital of Capital Medical University between August 2008 and December 2016 were collected.Of 228 patients,174 using biological mesh closure and 54 using primary closure were respectively allocated into the biological mesh group and primary closure group.Observation indicators:(1)intra-and post-operative situations;(2) postoperative complications (including short-term and long-term complications);(3) follow-up and survival situations.Follow-up using outpatient examination and telephone interview was performed to detect postoperative long-term complications,tumor recurrence or metastasis and overall survival up to December,2017.Measurement data with normal distribution were represented as（ x） ±s,and comparison between groups was analyzed using the independent-sample t test.Measurement data with skewed distribution were described as M (range),and comparison between groups was analyzed using the nonparametric test.Comparisons of count data were evaluated by the chi-square test or Fisher exact probability.Results (1)Intra-and post-operative situations:all the patients underwent successful ELAPE.The perineal operation time,time of indwelling perineal drainage-tube and hospital expenses were respectively (60 ± 50)minutes,(11.6 ± 2.4) days,(57 781± 11 337) yuan in the biological mesh group and (50±21) minutes,(8.9± 1.7) days,(53 714± 13 395)yuan in the primary closure group,with statistically significant differences between groups (t =3.327,7.691,-2.203,P＜0.05).The total operation time and duration of postoperative hospital stay were respectively (242±53) minutes,(13.0±5.0) days in the biological mesh group and (228±51) minutes,(12.0±5.0) days in the primary closure group,with no statistically significant difference between groups (t =1.701,1.309,P＞0.05).(2) Postoperative complications:26 and 19 patients in the biological mesh group and primary closure group had respectively perineal wound complications (1 patient combined with multiple complications),showing a statistically significant difference between groups (x2 =10.660,P＜0.05).The perineal wound infection,perineal hernia and disruption of perineal wound were respectively detected in 20,6,1 patients in the biological mesh group and 12,7,3 patients in the primary closure group,showing statistically significant differences between groups (x2 =3.931,5.282,P＜0.05).(3) Follow-up and survival situations:174 patients in the biological mesh group were followed up for 64 months (range,13-112 months),and 54 patients in the primary closure group were followed up for 51 months (range,23-76 months).The local recurrence rate,distal metastasis rate and overall survival rate were respectively 5.17％ (9/174),20.11％ (35/174),77.59％ (135/174) in the biological mesh group and 7.41％(4/54),24.07％(13/54),79.63％(43/54) in the primary closure group,with no statistically significant difference between groups (x2 =0.080,0.389,0.101,P＞0.05).Conclusions The biological mesh in the pelvic floor reconstruction of ELAPE for advanced low RC is safe and feasible.Compared with primary closure,biological mesh closure will extend perineal operation time and time of indwelling perineal drainage-tube,and increase hospital expenses,but doesn't affect total operation time and duration of postoperative hospital stay,meanwhile,it can also reduce the overall perineal wound complications,especially in perineal wound infection,perineal hernia and disruption of perineal wound.

Objective    To study the effect of deep sternal wound infections（DSWIs）treated by the techniques of pectoral major muscular(PM) turnover and non-suture remain after the wound restitution. Method    We retrospectively analyzed the clinical data of 23 patients with DSWIs in our hospital between June 2016 and December 2016. There were 13 males and 10 females at age of 4-73(54.5±19.5) years. There were 8 patients with concomitant diabetes mellitus and 1 patient with chronic obstructive pulmonary disease(COPD) and brain infarction. Eigteen patients were of type Ⅱ, 5 patients of type Ⅲ according to Pairolero’ classification in the DSWIs. Five patients were with remaining abscess cavity in the mediastinum by thoracic compute tomography(CT). Under general anesthesia the DSWIs debrided thoroughly. The PM elevated from the anterior pectoralis major fascia off subcutaneous tissue to lateral to anterior axillary line, the PM cutted off, then made to the muscle flap, turnover PM flap filled and fixed to sternal wound by lighten tensile suture, the subcutaneous tissue and skin sutured by cutting full-thickness. Results    The sternal reconstruction after debridement of the sternal wound was used by bilateral PM flap in the 17 patients, unilateral PM in 6 patients. There were 21(91.3%) patients in stage Ⅰ healing, 2 patients deferment healing of local cut skin without reoperation. There were 22 patients with non-paradoxical breathing during the postoperation. One death resulted from multiple-organ failure of the concomitant disease. The average of hospital day was 10.6 days. The wound healing was good by chest CT at 1 month after the operation. Conclusion    The sternal forming by the technique of the PM flap turnover, without remain of fremde stoffe in wound for DSWIs is distinctive method, evident effect.

Due to the deep anatomical location which is adjacent to the important organization, the operation on the diseases of lateral skull base area is still a challenging problem for neurosurgeons. This article briefly describes the history of the lateral skull base surgical approaches, advantages and disadvantages of each approach, indication and relative contraindication, and enumerates the application of neuroendoscope in the corresponding area, so as to offer help to choose the appropriate surgical approach according to the clinical characteristics; the application prospect of neuroendoscope in the relevant regions is discussed.

OBJECTIVE:To optimize the formulation of nanostructured lipid carriers loaded with lornoxicam (LN-NLC). METHODS:Emulsification-solvent evaporation method was used to prepare the LN-NLC. Using drug-lipid ratio,dosage of soy lec-ithin,liquid-lipid ratio (proportion of liquid lipid to total lipid) and dosage of emulsifier as factors,the overall normalized value was calculated by particle size,Zeta potential and entrapment efficiency as indexes was used as comprehensive index. Central com-posite design-response surface method was used to optimize the formulation and investigate the appearance and stability of prepared LN-NLC. RESULTS:The optimal formulation were as follows as drug-lipid ratio of 1:50,dosage of soy lecithin of 162.5 mg,liq-uid-lipid ratio of 25% and emulsifier dosage of 958.2 mg. The particle size of prepared LN-NLC was(96.9±3.3)nm,Zeta poten-tial was(-16.1±0.3)mV,entrapment efficiency was(60.1±0.9)%(n=3),which showed relative error of 2.47%,-4.55%,-0.17%with predicted value,respectively. The prepared LN-NLC was spherical. It had no obvious changes in particle size and Ze-ta potential in sealed storage for 30 d in 4 ℃,and the entrapment efficiency only declined 1.2%. CONCLUSIONS:The LN-NLC formulation is successfully optimized,and the LN-NLC has good stability.

Objective To observe the changes of serum and fecal taurine-conjugated bile acid levels and its association with glucose metabolism during the spontaneous development of type 2 diabetes in OLETO rats.Methods Twenty male OLETF rats(4 weeks old)were included and 10 male LETO rats of the same age were used as the normal control group.OLETF rats were fed with high fat diet whereas LETO rats were fed with normal diet.Serum and fecal taurine-conjugated bile acid levels of OLETF rats were tested at different stage of diabetes including baseline, normal glucose tolerance, impaired glucose tolerance and diabetes periods, and the association of taurine-conjugated bile acid level with body weight, blood glucose, and glucose-regulating hormones were also investigated.Results Compared with LETO rats, the baseline serum levels of taurine-conjugated bile acid in OLETF rats did not change, but the levels of fecal taurine-conjugated bile acid including taurine-conjugated chenodeoxycholic acid(TCDCA), taurocholic acid(TCA)and taurine-conjugated deoxycholic acid(TDCA)were significantly decreased [(14.25±7.18 vs 0.90±0.31)mg/kg,(7.12±4.14 vs 1.30±0.35)mg/kg,(4.30±1.78 vs 1.02±0.14)mg/kg, all P<0.01].During the development of diabetes, the fecal levels of TCDCA, TCA and TDCA were still lower than those in the control rats.TDCA was negatively associated with the level of fasting blood glucose(r=-0.470, P=0.032),but positively associated with the serum level of glucagon-like peptide(GLP)-l(r=0.406, P=0.044).Conclusion The decrease of intestinal taurine-conjugated bile acid level is involved in the development of diabetes in OLETF rats.Intestinal TDCA may regulate the secretion of GLP-1 by paracrine pathway.

OBJECTIVETo evaluate the laparoscopy combined with transperineal extralevator abdominoperineal excision (TP-ELAPE) for locally advanced low rectal caner.

METHODSClinical data of 12 patients with locally advanced low rectal cancer undergoing laparoscopy combined with TP-ELAPE in our department from May 2013 to March 2015 were retrospectively analyzed. There were 8 male and 4 female patients with median aged of 63 (46 to 72) years. The median distance from tumor lower margin to anal verge was 3.5(2.0 to 4.0) cm. A self-made transanal suit for minimally invasive operation was used to make a sealed lacuna outside the sphincter, thus laparoscope can be applied to perform transperineal operation.

RESULTSAll the patients underwent operations successfully without conversion to open abdominal operation. The median operating time was 206 (180 to 280) minutes with perineal operating time 95(80 to 120) minutes. The median intraoperative blood loss was 120(50 to 200) ml. The median postoperative hospital stay was 12(9 to 18 ) days. Postoperative pathology revealed that all circumferential margins (CRM) were negative. The area of sample horizontal section was (2 824±463) mm(2), and of outer muscularis propria was(2 190±476) mm(2). Postoperative complications included chronic sacrococcygeal region pain in 2 cases, urinary retention in 3 cases, perineal wound infection in 1 case. No perineal seroma, perineal hernia, wound dehiscence and sinus tract formation were observed. Among 8 patients with preoperative normal sexual function, sexual dysfunction occurred in 2 patients. There was no local recurrence and metastasis during a median follow-up of 21(12 to 34) months.

CONCLUSIONLaparoscopy combined with TP-ELAPE has the potential to simplify the operation procedure for low rectal cancer, can ensure the radical treatment and safety of operation, and may be carried out in experienced centers.

Abdomen ; Aged ; Anal Canal ; Blood Loss, Surgical ; Digestive System Surgical Procedures ; methods ; Female ; Humans ; Laparoscopy ; Length of Stay ; Male ; Middle Aged ; Neoplasm Recurrence, Local ; Operative Time ; Perineum ; Postoperative Complications ; Postoperative Period ; Rectal Neoplasms ; surgery ; Rectum ; Retrospective Studies