Objective:To investigate the current situation of students' academic procrastination behavior in medical colleges and universities and its influencing factors, and to put forward suggestions to reduce the academic procrastination of medical students.Methods:A total of 1 327 undergraduate students from three medical colleges and universities in Heilongjiang Province were randomly selected to receive questionnaire investigation on life satisfaction, anxiety, and academic procrastination. SPSS 23.0 was used for data analysis.Results:①The total procrastination scores of medical students were (35.00±8.92) points. ②There were statistical differences in the academic procrastination of medical students with different genders, whether the only children, the reasons for choosing the major, and the level of achievement ( P < 0.05). There was no statistical difference in academic procrastination among medical students of different ages and grades ( P > 0.05). ③Medical students' procrastination was positively correlated with their anxiety level ( r = 0.102, P < 0.01), and negatively correlated with life satisfaction ( r = -0.117, P < 0.01). ④Regression analysis showed that the following six predictive variables including the level of achievement, gender, life satisfaction, anxiety, reasons for choosing the major, and whether the only children could effectively explain the variance of 14.2% academic procrastination of medical students. Conclusion:The overall degree of academic procrastination of medical students is higher than that of non-medical students. And the students' achievement level, gender, life satisfaction, anxiety, the reasons for choosing this major and whether the only child are the influencing factors of academic procrastination.

AIM:To explore the depression-like behavior and cystathionine β-synthase (CBS)/hydrogen sulfide (H2S) levels of amygdala in posttraumatic stress disorder (PTSD) rats and to study the effect of exogenous H2S on PTSD rats.METHODS:Single prolonged stress paradigm was adopted to prepare PTSD animal model.Forced swimming test and sucrose preference test were used to evaluate the depression-like behavior.The content of CBS/H2S in amygdala tissue was measured by Western blot and methylene blue method.In vivo extracellular single unit recordings was used to examine the frequency of spontaneous discharges of amygdala neurons.RESULTS:The immobility time in forced swimming test of PTSD group increased and sucrose preference in sucrose preference test of PTSD group decreased compare with normal group (P<0.01).CBS/H2S level in amygdala tissue of PTSD group decreased compared with normal group (P<0.01).The immobility time of the rats in forced swimming test of NaHS+PTSD group decreased and the sucrose prefe-rence in sucrose preference test of NaHS+PTSD group increased compare with PTSD group (P<0.01).L-cysteine increased the frequency of spontaneous discharges of amygdala neurons (P<0.01).CONCLUSION:Depression-like behavior is aggravated in PTSD model rats owing to the inhibition of CBS/H2S content in amygdala tissue.The mechanism of behavior-improving effect of H2S on PTSD model rats is possibly related to excitating amygdala neurons and increasing the frequency of spontaneous discharges.

Objective To study the effects of fibroblast growth factor 2 (FGF2) on the proliferation and gene expression profiles of rabbit articular chondrocytes in vitro after different time periods of stimulation.Methods The chondrocytes were isolated and cultured in vitro,and the 3rd generation cells were harvested.Cells were divided into three groups.In the group 1 (FGF2 short-time action group),chondrocytes were cultured in medium with FGF2 for one day,and then transferred to fresh culture medium without FGF2 and cultured for another 6 days.In the group 2 (FGF2 long-time action group),chondrocytes were cultured in medium with FGF2 for 7 days.In the Group 3 (control group),chondrocytes were cultured in culture medium without FGF2 for 7 days.After culture for 1,3,and 7 days,the proliferation of chondrocytes in the all groups was detected respectively.Following extraction of mRNA,the gene expressions of BMP2,BMP4,SOX9 and COL2A1 of the chondrocytes in the all groups were determined by quantitative real-time polymerase chain reaction (qRT-PCR).The content of type Ⅱ collagen was measured via immunofluorescence staining.Results Compared with the control group,FGF2 promoted the proliferation of chondrocytes in the short-and long-time action groups and there was no significant difference between the two FGF2-treated groups.The results of qRT-PCR indicated that different treatment induced different gene expression profile.Particularly,compared with the control group and the FGF2 long-time action group,the expression of BMP2,BMP4,SOX9 and COL2A1 in the short-time action group were significantly upregulated at the 7th day.Immunofluorescence intensity of type Ⅱ collagen in the group 1 was stronger than that in the control group and group 2.Conclusions Different administration of FGF2 for different time periods induced different responses of chondrocytes.Short-term FGF2 stimulation was more beneficial to maintain the phenotype of chondrocytes and the synthesis of extracellular matrix.

ObjectiveTo explore the possible mechanism of adult offspring rats'anxiety-like behavior induced by parents experienced morphine addiction and withdrawal.MethodsEstablishing the model of Sprague-Dawley rats morphine addiction,Male and female rats were mated after morphine withdrawal 21 days.Meaning-while,saline control group was established in the same method.5 female and 5 male offspring's brains were obtained to observe the neuronal morphology of hippocampal CA1 through Golgi staining when they were 8 weeks old,the same number of female and male's hippocampus were derived after deeply anesthetized to perform the whole genome expression profiles analysis.ResultsThe total length and the number of basal dendrites branches on hippocampal CA1 neurons in offspring of morphine groups were significantly decreased compared to the offspring of saline group.Comparison with the offspring of saline group,663 up-regulated genes (ratios ≥2.0) and 499 down-regulated genes ( ratios ≤0.5 ) were detected in the male offspring of morphine groups,and 350 up-regulated genes (ratios ≥2.0) and 188 down-regulated genes (ratios ≤0.5) were done in the female.Furthermore,they included many genes associated with regulation of emotional behavior,such as 5-HT2c receptor up-regulation 7-fold,Igf-2 up-regulation 7.1-fold and reelin down-regulation 3.3-fold were observed.ConclusionExperienced morphine addiction and withdrawal in parents prior to mating leads to dysplasia of dendritic morphology in hippocampal CA1 neurons of adult offspring rats,and 5-HT2c,Igf-2,reelin expressing abnormally,which may be the possible mechanism of anxiety-like behavior in adult offspring rats.

Objective To explore the application value of paraffin embedding cell blocks from hydrothorax and ascite in diagnosis of tumors in the chest.Methods Of all clinical inspection for hydrothorax samples of thin-layer cytology,suspicious made paraffin embedding sediments of the tumor cells,immunohistochemical staining,identified the benign and malignant cells,determined the types of tumor cells and tissue origin.Results For liquid thin-layer cytology diagnosis of heterocyst,suspicious cases of malignant tumor,69 cases made the cell block combined with immunohistochemical staining,determined the malignant 51 cases,17 cases were benign,difficult to diagnose in 1 case,malignant determined the source of 46 cases,adenocarcinoma did not determine the source of 6 cases.Conclusion The technique of the embedding of paraffin embedding cells is of great value to the organization of the malignant and malignant tumors of the cells from hydrothorax and ascite.

ObjectiveTo investigate the relationship between complement-3(C3) and progression of early cerebral infarction.Methods168 consecutive patients with acute cerebral infarction within the first 24 hours from onset were recruited.Fasting venous blood sample was drawn on the morning of the second or the third day after admission.C3 and other clinical chemistry variables were measured.The relationship of C3 and progressing stroke(PS) was analyzed by Logistic regression.Results68 cases(40.48%) were considered as PS.Level of serum C3 in PS patients was 1.28±0.20 g/L higher than in those with non-PS(1.16±0.25 g/L,P=(0.000)).A higher C3 accompanied a higher tendency of prevalence of PS(P=0.001).Logistic regression analysis showed that C3 was significantly correlated with PS(OR for each 1.0 g/L=7.27;95% CI=1.52～36.39; P=0.013).ConclusionElevated serum C3 may play an important role in the prevalence of PS.

Objective　To observe the short-term and long-term effects of leptin on hepatic glucose oxidation and glucokinase gene expression. Methods　Rat hepatic cell line BRL was incubated with leptin of different doses (range from 10?ng/ml-200?ng/ml) for 1?h or 24?h. Glucose oxidation was determined by liquid scintillation counting. Glucokinase gene expression (corrected by β-actin) was determined by reverse transcription semi-quantitative polymerase chain reaction. Results　Treatment with leptin 10?ng/ml for 1?h had no significant effects on glucose oxidation in hepatic cells. However, at the doses ranging from 50?ng/ml to 200?ng/ml, leptin significantly inhibited glucose oxidation. These effects disappeared when the hepatic cells were exposed to leptin for 24?h. Glucokinase mRNA expression was reduced significantly after both 1?h and 24?h exposure to leptin (100?ng/ml) as compared to that of the control group. Conclusion　A low dose of leptin has no significant effect on glucose oxidation in hepatic cells. A relatively high dose of leptin has an acute inhibitory effect on the glucose oxidation in hepatic cells. This effect may likely involve the inhibition of glucokinase gene expression. The inhibitory effect on glucose oxidation is transient and disappears with prolonged exposure time.

Klebsiella pneumoniae(K.pneumoniae)is important zoonotic pathogen causing multiple local and systemic infections.At present,the drug resistance of K.pneumoniae is serious,and mul-tiple drug-resistant strains continue to emerge.Even the incidence of drug-resistant K.pneumoniae infection is increasing year by year.In this study,K.pneumoniae clinical isolate 71Y was used as the starting strain,and a phage with strong lytic activity was successfully obtained from sewage samples.The phage was named vB_KpnP_71Y(abbreviated as P71Y),the general biological char-acteristics and genome of P71Y were further studied and analyzed.P71Y can form clear plaque with a diameter of 2-5 mm and a translucent halo ring on the host bacterium 71Y lawn.Electron micros-copy observation shows that P71Y is a member of the order Autographiviridae and family Caudovi-rales.The incubation period for P71Y infected with K.pneumoniae is about 3 minutes,and one in-fection cycle lasts for about 50 minutes.Each infection of a bacterium can produce approximately 58 progeny phage virus particles.Cleavage spectra showed that the phage could lysate K20 and K57 serotypes of K.pneumoniae.The phage had good stability at 4-50 ℃ and pH values of 3-12.Genom-ic analysis revealed that P71Y contained a double-stranded DNA with a total length of 39 700 bp and a G+C content of 53％.There are a total of 53 coding genes,P71Y does not carry virulence factors and drug resistance genes,which has shown genetic safety.This study isolated a novel lytic phage that can cleave multiple serotypes of K.pneumoniae,which provided experimental materials for the study of the interaction between bacteriophages,different serotypes of K.pneumoniae,and the application of phage for the prevention and controlling of infections caused by multi-drug-re-sistant K.pneumoniae.

Objective To investigate the clinical value of the polymerase chain reaction (PCR) technique in detection of pediatric helicobacter pylori(HP) infection.Methods A total of 130 children with different digestive tract symptoms received esophagogastroduodenoscopy,and 120 children between 3 and 17 years old were enrolled.The gastric antrum mucosa was taken under the gastroscope for 2 blocks,and the gastric juice was absorbed as the specimen.One block of gastric antrum mucosa was examined histopathologi-cally,and the other block of gastric antrum mucosa and gastric juice were examined by PCR.We used the primers UreC,HP-16s,CSTP to detect HP,and then used the primers Cag750 and Cag595 to detect CagA. Results A total of 28 cases(23.33%) of upper gastrointestinal ulcer were detected by gastroscopy,and HP was detected by histopathological method in 26 cases(21.67%),and 41 cases(34.17%) were detected by PCR method.The detection rate of HP by PCR was significantly higher than that of HP in pathological method (χ2= 4.659,P = 0.031). By pathological examination of HP,14 cases (50%) and 12 cases (13.04%) with peptic ulcers and no peptic ulcers were detectd,and the difference in detection rate was statistically significant(χ2=17.275,P<0.001).Samples of children with peptic ulcers and no peptic ulcers were detected in 16 cases(57.14%) and 25 cases (27.17%) by PCR,and the difference in detection rate was statistically significant (χ2=8.572,P=0.003).The CagA were detected in 7 cases of peptic ulcers and 7 cases of non peptic ulcers by PCR,and the difference in detection rate was statistically significant(25.00%vs 7.61%,χ2=6.300,P=0.012).Conclusion The PCR method could quickly and sensitively detect the HP and its CagA gene,and the detection of gastric mucosa and gastric juice by PCR could improve the detection rate of HP.A combination of PCR and pathological method is suggested as the detection method for children′s HP infection.

Objective To investigate the effects of Helicobacter pylori( HP) on gut microbiota in children by comparing the difference of gastric microbiota between HP-positive and HP-negative individuals. Methods Genome was extracted from excrements of 8 HP-positive cases and 8 HP-negative cases. After genomic extraction,the hypervariable region of 16S rRNA gene were amplified and a small fragment library was constructed,and high-throughput sequencing was carried out, then the data of the lower machine was effectively sequenced by biological information processing. We could seek for the species that have changed significantly due to HP infection by comparing the differences in the composition of intestinal flora between the two groups. Results Compared with HP-negative group,HP-positive group showed less OTUs. The dif-fenece of biodiversity between them was conspicuous. The Caproiciproducens,Enterobacteriaceae,Enterobac-teriales,Blautia-obeum,Esherichia-albertli,human-gut-metagenome and Dorea in HP-positive group were sig-nificantly higher than HP-negative group,while the Bacteroides-uniformis, Bacteroidaceae and Bacteroides in HP-negative group were significantly higher than HP-positive group. Conclusion HP could significantly affect the structure and composition of gut microbiota in children.