Objective To understand the status and related influencing factors of critical thinking of medical students, so as to provide recommendations for the training methods of critical thinking of medical students. Methods A total of 380 medical students in third and fourth grade of a medical university were investigated by using the California Critical Thinking Tendency Questionnaire and stratified random sam-pling method. 356 valid questionnaires were recovered. SPSS 22.0 software was used for statistical analysis, including t-test, analysis of variance and multiple linear regression analysis and other methods. Results The Cronbach'sαcoefficient of the scale was 0.728, and the cumulative variance contribution rate was 68.43%. The average score of positive critical thinking ability of medical students was 196.02, showing that they had positive thinking ability. Multiple linear regression analysis showed that the degree of extracurricular read-ing, whether there was a part-time job, and the students' self-study time per week had positive correlation with the critical thinking of medical students (P<0.05). Conclusion The critical thinking ability of medical students needs to be improved and the factors of critical thinking need to be further studied, and the research and practice of cultivating medical students' critical thinking ability must be deepened.

Objective To observe the clinical effect of metformin and insulin in gestational diabetes mellitus(DM) patients and their effects on neonates.Methods From August 2012 to October 2016,60 patients with gestational diabetes mellitus were divided into control group(n=30) and observation group(n=30) by random number method.The control group was treated with insulin and the observation group was treated with metformin on the basis of the control group.The clinical effect and the effect on neonatal were compared between the two groups.Results The level of glycosylated hemoglobin in the observation group was higher than that in the control group(P<0.05).In the observation group,the levels of fasting plasma glucose,postprandial blood glucose 2 hours after meals and 4 hours postprandial blood glucose were lower than those in the control group(P<0.05).There were no significant differences in the levels of CysC and Hcy between the two groups before treatment(P>0.05).The incidence of fetal distress,respiratory distress,macrosomia and the incidence of premature delivery were significantly lower than those of the control group(P<0.05).The amount of insulin in the observation group was less than that in the control group(P<0.05).The level of CysC and Hcy in the observation group was significantly lower than that in the control group(P<0.05).Conclusion Compared with insulin therapy,metformin could improve the outcome of neonatal patients,which might be worthy to be popularized and used in the treatment of gestational diabetes mellitus.

Objective To explore the CT manifestations,incidence,etiology and clinical significance of hyperostosis frontalis in-terna (HFI).Methods CT features of 243 cases HFI were analyzed retrospectively.Based on the maximum thickness of the inner table of the frontal bone,HFI was classified into 4 grades as follows:GradeⅠ─ thickness of 2.8-6.0 mm,GradeⅡ─ thickeness of 6.1-10.0 mm,Grade Ⅲ ─ thickness of 10.1-14.0 mm,Grade Ⅳ ─ thickness of greater than 14.1 mm.According to the in-crassating direction,HFI was classified into inward,outward and intermediate type.Results The inner table of the frontal bone was incrassated in all cases (n=243).The thickness ranged between 2.93 mm and 14.64 mm,including GradeⅠin 68 cases (28.0%), GradeⅡin 71 cases (29.2%),Grade Ⅲ in 69 cases (28.4%)and Grade Ⅳ in 35 cases (14.4%).There were inward type in 82 ca-ses (33.7%),outward type in 59 cases (24.3%)and intermediate type in 102 cases (42.0%).The incidence of HFI was 5.47% in postmenopausal women,with 7.14% in overweight and 9.09% in obese women respectively.Conclusion HFI is common in the postmenopausal women,and CT manifestations of HFI are characteristic.

Objective To evaluate the effects of dexmedetomidine on the expression of spinal matrix metalloproteinase-9 (MMP-9) in a rat model of neuropathic pain (NP).Methods Eighty-one adult male SpragueDawley rats,weighing 190-230 g,were randomly divided into 3 groups (n =27 each) using a random number table:sham operation group (group S); group NP; dexmedetomidine group (group Dex).The animals were anesthetized with intraperitoneal 10％ chloral hydrate 350 mg/kg.The right sciatic nerve was exposed and 4 loose ligatures were placed on the sciatic nerve at 1 mm intervals with 4-0 silk thread in NP and Dex groups.In group Dex,dexmedetomidine 50 μg/kg was injected intraperitoneally once a day starting from the end of operation until the animals were sacrificed.The equal volume of normal saline was given instead of dexmedetomidine in S and NP groups.Paw withdrawal threshold to von Frey filament stimulation (MWT) and paw withdrawal latency to thermal stimulation (TWL) were measured at 1 day before operation (To,baseline) and 5,9 and 16 days after operation (T1-3).Nine animals were sacrificed after measurement of pain threshold at T1-3 and their lumbar segments (L4,5) of the spinal cord were removed for detection of MMP-9 expression (by immuno-histochemistry) and tumor necrosis factor-alpha (TNF-α) content (by ELISA).Results Compared with group S,MWT was significantly decreased,TWL was shortened,and the levels of MMP-9 and TNF-α were increased at T1-3 in NP and Dex groups.Compared with NP group,MWT was significantly increased,TWL was prolonged,and the levels of MMP-9 and TNF-α were decreased at T1-3 in Dex group.Conclusion Dexmedetomidine can inhibit up-regulation of MMP-9 expression,and decrease inflammatory responses,thus attenuating NP in rats.

Objective To evaluate the effects of propofol on the expression of hippocampal γ-aminobutyric acid (GABAA) and NMDA receptor in a rat model of inflammatory pain (IP).Methods A total of 32 female Sprague-Dawley rats,weighing 180-220 g,were randomly divided into 4 groups (n =8 each):control group (group C),group IP,and different doses of propofol groups (P1,2 groups).IP was induced by injection of formalin.In group C,normal saline and dimethyl sulfoxide (DMSO) 0.1 ml/kg were injected intraperitoneally.In group IP,normal saline and DMSO 0.1 ml/kg were injected intraperitoneally,and 5 min later formalin was injected.In P1,2 groups,propofol 30 and 100 mg/kg were intraperitoneally injected,respectively,and 5 min later formalin was injected.The pain behavior of rats was observed within 1 h after injection of formalin and pain intensity scoring (PIS) value was calculated.The animals were sacrificed at 1 h after injection of formalin and the hippocampi were isolated for determination of GABAA and NMDA receptor expression by immunohistochemisty.Results Compared with group C,PIS value was significantly increased,GABAA and NMDA receptor expression was up-regulated in IP and P1.2 groups.Compared with group IP,PIS value was significantly decreased,GABAA receptor expression was up-regulated,and NMDA receptor expression was down-regulated in P1,2 groups.PIS value was significantly lower,GABAA receptor expression was higher,and NMDA receptor expression was lower in group P2 than in group P1.Conclusion Intraperitoneal propofol can down-regulate NMDA receptor expression in hippocampi of rats with IP,thus inhibiting responses to pain sensitivity; intraperitoneal propofol can up-regulate hippocampal GABAA receptor expression,thus enhancing endogenous mechanism of analgesia.

AIM To study the tissue distribution of strychnos nux vomica alkaloids in rats. METHODS Rats were given strychnos nux vomica alkaloids intravenously and strychnine(S), brucine(B), strychnine N oxide(SNO), brucine N oxide(BNO) in every tissue was determined by HPLC timely. RESULTS The concentration of S, B, SNO and BNO were high in brain and spinal marrow. CONCLUSION S, B, SNO and BNO all have the ability to permeate blood brain barrier.

Objective To explore the correlation between heart rate recovery after exercise test and disease severity in patients with chronic obstructive pulmonary disease(COPD)and assess its impact on the exercise capacity of COPD patients.Methods Arterial blood gas analysis, pulmonary lung function test and cardiopulmonary exercise testing were performed in 60 patients with stable COPD and 50 healthy volunteers.Based on the heart rate recovery after exercise test, COPD patients were divided into normal heart rate recovery group(n =41)and abnormal heart rate recovery group(n =19).Results The COPD patients had lower exercise capacity(peak oxygen uptake as percentage of predicted value, peak VO2％ pred)(66 ± 15vs.89±11, P＜0.01), peak heart rate [(134±21)vs.(149±13)beats/min, P＜0.01], heart rate recovery[(18 ± 9)vs.(27 ± 10)beats/min, P ＜ 0.01] and higher resting heart rate [(83 ± 13)vs.(77 ± 13)beats/min, P ＜0.01] than the controls.Compared with normal heart rate recovery group, forced expiratory volume in one second as percentage of predicted(FEV1 ％ pred)and exercise capacity decreased more significantly in abnormal heart rate recovery group(38 ± 15 vs.52 ± 16, P＜0.05 and 57 ± 12 vs.71 ±14, P ＜0.01).Heart rate recovery was significantly correlated with FEV1％ pred and peak V O2％ pred(r=0.42, P ＜ 0.01 and r =0.52, P ＜ 0.01).Multivariate regression analysis showed that heart rate recovery and FEV1 ％ pred could be used as independent predictors of exercise capacity in COPD patients.Conclusion In COPD patients, heart rate recovery is correlated with the degree of disease severity and it may be an independent predictor of exercise capacity.

Objective To explore the feasibility of labeling in vitro rabbit osteoblasts with Qtracker and the features of Qtracker-labeled rabbit osteoblasts. Methods A healthy male rabbit, 3 months old, weighing 2 kg, was used in this study. After bone marrow was aspirated, bone marrow stromal cells (BMSCs) were isolated and cultured using the adherence method in vitro. The third passage of BMSCs was induced into osteablasts before incubation with Qtracker at concentrations of 1, 2, 4, 8, 16, 32 nmol/10~6 cells (Groups A, B, C, D, E, F respectively). Cells not labeled by Qtracker served as negative control (Group G). The following parameters were measured: induction, differentiation and determination of rabbit osteoblasts; the optimal mass concentration of Qtracker labeling by fluorescence microscopy and flow cytometry; the cell sur-vival rates at various concentrations of Qtraeker labeling by trypan-blue exclusion; Qtracker-labeled cell pro-liferation by MTr. Results The primary and the passage rabbit BMSCs were chiefly of fusiform shape. Rabbit BMSCs differentiated into osteoblasts following induction. The osteoblasts cytoplasm showed green fluorescence under fluorescence microscopy after being labeled by Qtracker. The mean labeling rate increased with the increased concentration of Qtracker, reaching up to (93.58±2.08) % after incubation at 8 nmol/ 10~6 cells by fluorescence microscopy, and (95.24±1.31) % by flow cytometry. There were no significant differences between Groups D, E, F(P>0.05), but significant differences were found between Groups A, B, C and Groups D, E, F (P<0.05). The labeling rate for Group G was 0. The cell survival rates were all above 96% (P>0.05) . No significant differences were found in the cell proliferation among various con-centrations (P>0.05). Conclusions Qtraeker can be used as a labeling marker for rabbit osteoblasts. When the concentration is at 8 nmol/10~6 cells, optimal labeling effect can be achieved. Rabbit osteoblasts labeled with Qtracker are of high efficiency and safety.

Objective To investigate the effects of D-tryptophan (D-Trp) on the formation of Streptococcus mutans (S. mutans) biofilm and the dispersal of 24 h-old biofilm, and the drug susceptibility of S. mutans against chlorhexidine (CHX) under the role of D-Trp. Methods Optical density assay was used to evaluate the growth curve of S. mutans exposed to 5.0 mmol/L D-Trp for 28 h. The non-treated group was not added with D-Trp. After treatment with 1.0, 2.5 and 5.0 mmol/L D-Trp, crystal violet staining was used to observe the changes of S. mutans biofilm formation in treatment group and non-treatment group. Crystal violet staining and confocal laser scanning microscopy (CLSM) were applied to illustrate the effects of 1.0, 2.5 and 5.0 mmol/L D-Trp on the dispersal of 24 h-old S. mutans biofilm. Resazurin sodium was used to indicate the effect of 5.0 mmol/L D- Trp on the minimum inhibitory concentration (MIC) and the minimum biofilm inhibitory concentration (MBIC) of treatment groups and negative control group. Results The growth curves of planktonic S. mutans within 28 h was consistent in treatment group and the non-treated group, both attained exponential phase after 4 h and reached stationary phase at 22 h. Notably, when compared with non-treated group, the biomass of S. mutans biofilm was increased with time from 0 to 72 h after treatment with 1.0, 2.5 and 5.0 mmol/L D-Trp. And at the same time point, the biomass was significantly less in each subgroup of treatment group than that of non-treated group (P<0.05). Crystal violet staining demonstrated that values of biomass(OD570)were less in treatment groups treated with 1.0, 2.5 and 5.0 mmol/L D-Trp than those of non-treated group (P<0.01). CLSM also showed that bacteria was adhered to the surface of media intreatment groups treated with 1.0, 2.5 and 5.0 mmol/L D-Trp. The values of biomass were lower in treatment groups than those of non-treated group (P<0.01). The MIC against S. mutans was 0.073 mg/L in both experimental group and negative control group. The values of MBIC were 0.293 mg/L and 2.344 mg/L in experimental group and negative control group, respectively. Under the action of 5.0 mmol/L D-Trp, the MBIC of S. mutans was reduced to 1/8. Conclusion Results indicate that D-Trp may inhibit the formation of S. mutans biofilm and promote the dispersal of biofilm already formed. D-Trp may further help CHX exert its bactericidal activity to S. mutans.

Objective To evaluate the role of spinal AMP-activated protein kinase (AMPK) signaling pathway in reduction of neuropathic pain (NP) by dexmedetomidine in rats.Methods One hundred twenty adult male Sprague-Dawley rats, weighing 180-220 g, were randomly divided into 4 groups (n=30 each) using a random number table: sham operation group (group S);group NP;dexmedetomidine group (group Dex) and AMPK inhibitor group (group AI).The animals were anesthetized with intraperitoneal 10％ chloral hydrate 350 mg/kg.The right sciatic nerve was exposed, and 4 loose ligatures were placed on the sciatic nerve at 1 mm intervals with 4-0 silk thread in NP and Dex groups.In group Dex, dexmedetomidine 50 μg/kg was injected intraperitoneally once a day starting from the end of operation until the animals were sacrificed.In group AI, AMPK inhibitor Compound C 20 mg/kg was injected intraperitoneally at the end of operation, and the other treatments were similar to those previously described in group Dex.The equal volume of normal saline was given instead of dexmedetomidine in S and NP groups.The mechanical paw withdrawal threshold to von Frey filament stimulation (MWT) and thermal paw withdrawal latency (TWL) were measured at 1 day before operation (baseline) and 2, 8 and 14 days after operation (T0-3).Results Compared with group S, the MWT was significantly decreased, and the TWL was shortened at T1-3 in NP, Dex and AI groups (P＜0.05).Compared with group NP, the MWT was significantly increased, and the TWL was prolonged at T1-3 in group Dex (P＜0.05) , and no significant change was found in MWT and TWL in group AI (P＞0.05).Conclusion Spinal AMPK signaling pathway is involved in reduction of NP by dexmedetomidine in rats.