PBL(Problem-Based Learning, PBL) is a problem-oriented and effective supplementary teaching method. PBL is giving a great help to improve self-learning, communication and cooperation, thinking and problems solving abilities for the students. In the process of PBL teaching, attention should be paid to two important items. One item is the role transfer for the teacher. Teacher is only a guider in PBL teaching, teacher should avoid excessive interfere of the process for keeping the passion and enthusiasm of the students. Meanwhile, students should always be realized that they are the main part in PBL teaching, they should not depend on their teacher too much. Another important item is how to find and solve the frequently encountered problems, in order to avoid students wandering from the subject, and lead them toward the main goal to get effective teaching and learning.

Objective To observe the effect of fructose(Fru),glucose (Glc)and exogenous nitric oxide donor sodium nitroprusside(SNP)on the germination of Psychotria rubra(Lour.)Poir. seeds under drought stress,and to explore the optimal concentration for clearing the drought stress. Methods We established the drought stress model of Psychotria rubra(Lour.)Poir. seeds with 15％(volume fraction)PEG6000 and 0.4 mol/L D-mannitol, measured the germination rate and germination index of Psychotria rubra (Lour.)Poir. seeds under drought stress combined treatment with different concentrations of Fru (0,300,500 μmol/L),Glc (0,300,500 μmol/L) and SNP(0 , 100 , 200 μmol/L). Results The germination process of Psychotria rubra(Lour .) Poir . seeds was significantly suppressed by drought stress. Fru,Glc and SNP could significantly promote the germination of Psychotria rubra (Lour.) Poir. seeds under drought stress. The optimal condition for clearing drought stress induced by 15％ PEG6000 was Fru 300 μmol/L, Glc 500 μmol/Land SNP 200 μmol/L, and the germination rate was 95％ under the optimal condition . The optimal condition for clearing drought stress induced by D-Mannitol was Fru 500 μmol/L, Glc 500 μmol/L and SNP 100 μmol/L, and the germination rate arrived to100％. Conclusion Fru,Glc and SNP can significantly alleviate the negative impact induced by drought stress for the Psychotria rubra(Lour.)Poir. seed germination,improve the drought-resistant ability of the seeds.

Objective To compare the pharmacognosy characteristics of aerial roots of Ficus microcarpa Linn.f. and Ficus elastica Roxb. ex Hornem.. Methods Fresh aerial roots were harvested and were used as the experimental samples. Stereoscopy was used for the observation of macroscopic appearance of Ficus microcarpa Linn.f. and Ficus elastica Roxb. ex Hornem.,and the microscope was used for the examination of their microscopic features of the velamen surface, cross section of root tip, cross section and longitudinal section of the posterior root, and powder. Results The appearance characteristics of the two species were as follows:the number of aerial roots of Ficus microcarpa Linn. f. was more,and the diameter was smaller than that of Ficus elastica Roxb. ex Hornem. The root tips of Ficus microcarpa Linn. f. aerial roots were light yellow turning to yellow-white, covered with gray or yellowish-white lenticels;the root tips of Ficus elastica Roxb. ex Hornem. aerial roots were light yellow or yellow, covered with gray lenticels. Microscopic identification results of the two plants were as follows:the primary xylems of transverse section of root tips and posterior roots of Ficus microcarpa Linn.f. and Ficus elastica Roxb. ex Hornem. were different,the former being five to seven heptarch,and the latter being six to eleven heptarch. Both of the two species had non-articulated unbranched laticifers in their longitudinal section of posterior root, and the diameter of Ficus. elastica Roxb. ex Hornem. was slightly larger than that of Ficus microcarpa Linn. f.. The powder of Ficus microcarpa Linn. f. was red brown,with spiral and pitted vessels;Ficus elastica Roxb. ex Hornem. was yellow brown,with single small and large pitted vessels,and the color of its fiber was shallow or nearly colorless or even transparent, with lines of cluster crystal. Conclusion The results will provide evidence for the identification , exploitation and utilization of Ficus microcarpa Linn . f . and Ficus elastica Roxb. ex Hornem.

OBJECTIVETo compare the prognosis of small hepatocellular carcinoma patients with hepatitis B virus infection versus hepatitis C virus infection.

METHODS413 patients receiving curative resections at Tianjin Cancer Hospital for small HCC (< or = 3 cm) from January 1997 to December 2003 were divided into four groups: HCV only (n = 75), HBV only (n = 251), HBV and HCV (n = 33), and neither HBV nor HCV (NBNC, n = 54). The preoperative status and postoperative recurrence were recorded. Survival analysis were used to assess the impact of HBV/HCV status on HCC recurrence.

RESULTSPatients with HCV were associated with older age, lower mean preoperative platelet counts and albumin levels, higher mean prothrombin time, alanine aminotransferase and total bilirubin levels. Tumors in patients with HCV are multinodular and less differentiated, and were associated with a higher incidence of vascular invasion and cirrhosis. During the follow-up, the HCV group showed a higher incidence of intrahepatic recurrence and multiple recurrent lesions than the other patients.

CONCLUSIONSHCC patients with HCV infection tended to be older, and were characterized by more severe cirrhosis and higher incidence of tumor multinodular. The statistically significant determinants of reoccurrence in patients with small HCC were HCV infection, presence of vascular invasion and multiple tumors.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Carcinoma, Hepatocellular ; pathology ; surgery ; virology ; Female ; Follow-Up Studies ; Hepatectomy ; Hepatitis B ; complications ; epidemiology ; Hepatitis C ; complications ; epidemiology ; Humans ; Liver Cirrhosis ; pathology ; virology ; Liver Neoplasms ; pathology ; surgery ; virology ; Male ; Middle Aged ; Neoplasm Recurrence, Local ; epidemiology ; Prognosis ; Retrospective Studies ; Risk Factors ; Survival Analysis ; Young Adult

OBJECTIVETo investigate the psychosocial status and related factors among university students during severe acute respiratory syndrome (SARS) epidemic in Beijing.

METHODSBy means of stratified cluster sampling, symptom checklist-90 (SCL-90) and questionnaire on general information were applied among 6800 students in three universities in Beijing.

RESULTSThere were 6280 valid questionnaires gathered. In order to control and prevent SARS, strict management was conducted in three universities which providing various social supports. Out of the 6280 students, 460 had SCL-90 positive symptoms with a rate of 7.3%. Risk factors of SCL-90 positive symptom were found as follows: major in arts (OR = 2.00), misconception on the control and prevention of SARS (OR = 1.91), considering measures non-effective (OR = 2.25), and do not believe that SARS can be under control (OR = 3.57). Protective factors of SCL-90 positive symptom would include as: being female (OR = 0.77), being graduate students (OR = 0.38), and being not much influenced on study and daily life during the period of strict management (OR = 0.54).

CONCLUSIONPsychosocial status of students was influenced by their knowledge and attitude on SARS. Various social supports might keep the university students to having a healthy psychosocial status.

Adolescent ; Adult ; Awareness ; China ; epidemiology ; Disease Outbreaks ; prevention & control ; Female ; Health Knowledge, Attitudes, Practice ; Humans ; Male ; Quarantine ; methods ; organization & administration ; psychology ; Risk Factors ; Sampling Studies ; Severe Acute Respiratory Syndrome ; epidemiology ; prevention & control ; psychology ; Surveys and Questionnaires ; Time Factors ; Universities

OBJECTIVETo investigate the distribution characteristics and influencing factors of mental workload of teachers in primary schools.

METHODSNational Aeronautics and Space Administration-Task Load Index (NASA-TLX) was used to assess the mental workload levels for 397 teachers of primary schools in a city.

RESULTSThe mental workload (64.34+10.56) of female teachers was significantly higher than that (61.73+ 9.77) of male teachers (P<0.05). The mental workload (65.66+10.42) of "-35" years old group was the highest. When age of teachers was younger than 35 years old, there was a positive correlation between the mental workload and age (r=0.146, P<0.05). When age of teachers was older than 35 years old, there was a negative correlation between the mental workload and age (r=-0.190, P<0.05). The teachers with higher education level felt higher mental workload (unstandardized coefficients B=1.524, standardized coefficients /=0.111, P<0.05). There was a positive correlation between the mental workload and working hours per day (unstandardized coefficients B =4.659, standardized coefficients/3 =0.223, P<0.001).

CONCLUSIONMental workload of the teachers in primary schools is closely related to age, educational level and work hours per day. Work hours per day is an important risk factor for mental workload. Reducing work hours per day (8 hours) is an effective measure of alleviating the mental workload of teachers in primary schools.

Adolescent ; Adult ; Aged ; Faculty ; Female ; Humans ; Male ; Middle Aged ; Schools ; Stress, Psychological ; epidemiology ; Surveys and Questionnaires ; Workload ; psychology ; Young Adult

OBJECTIVETo evaluate the effects of basic fibroblast growth factor (FGF-2) and vascular endothelial growth factor (VEGF) on the proliferation, migration, and adhesion of human periodontal ligament stem cells (PDLSC) in vitro.

METHODSHuman PDLSC were cultured in vitro using tissue culture method.The cells were cultured and incubated with various concentrations of FGF-2 and VEGF [A:α-MEM with 2% fetal bovine serum (FBS) (control 1); B:A supplemented with 20 µg/L FGF-2; C:A supplemented with 10 µg/L VEGF; D:A supplemented with 20 µg/L FGF-2 and 10 µg/L VEGF; E:α-MEM with 10% FBS (control 2); F:E supplemented with 20 µg/L FGF-2; G:E supplemented with 10 µg/L VEGF; H:E supplemented with 20 µg/L FGF-2 and 10 µg/L VEGF]. Soluble tetrazolium salts assay was used to evaluate the proliferative capacity on the 1st, 3rd, 5th and 7th d. Then the groups were changed according to result of the proliferation assay (control:α-MEM with 2% FBS; FGF-2 group:control supplemented with 20 µg/L FGF-2; VEGF:control supplemented with 10 µg/L VEGF; Combination group:control supplemented with 20 µg/L FGF-2 and 10 µg/L VEGF). The cell cycle, migration and adhesion capacities were evaluated using flow cytometer, soluble tetrazolium salts assay, cell adhesion assay and scratch wound-healing motility assay.

RESULTSIn 2% volume fraction serum containing medium, FGF-2 and VEGF did not stimulate the cell proliferation. However, in 10% serum condition, in groups treated with FGF-2 for 3,5 or 7 d, the A value was (1.22 ± 0.17, 2.15 ± 0.19, 2.72 ± 0.11) respectively, which were significantly higher than that in the control group (0.76 ± 0.16, 1.25 ± 0.06, 1.64 ± 0.09) (P < 0.01) while lower than that in the group treated with FGF-2 and VEGF in combination on the 5 th and 7 th d (2.46 ± 0.17, 3.18 ± 0.27) ( P < 0.05). The A value in the VEGF group on the 5 th and 7 th d is higher than the control group while lower than the FGF-2 group (1.66 ± 0.05, 2.13 ± 0.13) (P < 0.05). Flow cytometer showed that the proliferation index in VEGF group [(34.3 ± 2.0)% ] were significantly lower than those in FGF-2 [(46.8 ± 3.2)%] group and (FGF-2+ VEGF) group [(45.0 ± 4.0)%] but higher than in the control group [(14.5 ± 1.7)%] (P < 0.01). The cell migration assay indicated that the group stimulated with FGF-2 showed no migration promoted effect. Cell adhesion assay showed that the ratio of the adhesive cells number to the original cells number is greater in the FGF-2 group (79 ± 4) than in the VEGF group (62 ± 4) (P < 0.05). Light microscope identified a better cellular morphology on the adhesive surface in the group with FGF-2 than groups without FGF-2.

CONCLUSIONSBoth FGF-2 and VEGF could simulate the proliferation of PDLSC in a dose dependent manner, and showed an synergistic effect. FGF-2 was more effective to promote the adhesive capacity of PDLSC compared with VEGF. VEGF could facilitate the migration of PDLSC to the wound side.

Adult ; Cell Adhesion ; drug effects ; Cell Movement ; drug effects ; Cell Proliferation ; drug effects ; Cells, Cultured ; Dose-Response Relationship, Drug ; Drug Synergism ; Fibroblast Growth Factor 2 ; administration & dosage ; pharmacology ; Humans ; Periodontal Ligament ; cytology ; Stem Cells ; cytology ; Time Factors ; Vascular Endothelial Growth Factor A ; administration & dosage ; pharmacology ; Young Adult

Objective It has traditionally been difficult to isolate and culture mouse bone marrow mesenchymal stem cells (BMSC),which has low success rate.And thus restricts the development of related research to some extent.We aimed to optimize the whole bone marrow adherent method for isolation and culture of mouse bone marrow mesenchymal stem cells and search for an effective method of inducing BMSCs to differentiate into alveolar epithelial cells.Methods Bone marrow contents harvested from the tibia and femur of C57BL/6 mice were cultured based on the whole bone marrow adherent method.The timing and split ratios of passage were determined according to the size and number of cell colonies.After 6 passages,cells were counted to detect cell proliferation ability,surface markers were examined by flow cytometry and Small Airway Epithelial Cell Medium (SAEpiCM) was used to induce the differentiation of BMSCs.Results With the increase of passages and the purity of BMSCs,the proliferation of cells at passages 6 tended to be stable.Flow cytometry showed that they were strongly positive for bone marrow mesenchymal stem cell surface markers CD29 and Sca-1 (99.1％,88.5％),but almost negative for the surface marker of hematopoietic stem cells CD117 (0.008 2％).BMSCs cultured in SA-EpiCM showed an epithelium-like morphological change and expressed surfactant associated protein C,a specific marker of alveolar epithelial cells.Conclusion It is effective to isolate and culture mouse bone marrow mesenchymal stem cells by adjusting the timing and split ratios of passage according to the size and number of the clonal cell colonies,which possessed the potential to differentiate into alveolar epithelial cells.

Objective To identify the pharmacognosy features of Dichrocephala auriculata(Thunb.)Druce,and to summarize its identification characteristics,so as to lay a foundation for further study and development of the drug. Methods By original plant identification and microscopic identification methods,we observed the features of the whole plant of Dichrocephala auriculata(Thunb.)Druce. Results The morphological characteristics of the original plant showed as follows:the whole aerial part was covered with tomentum;roots belonged to taproot root system;the alternate leaves were long oval-shaped, pinnatipartite, or divided;flowers were small, presented as capitulum, arranging in umbrella-shape, with several outer layers of white flowers and several inner layers of yellow green flowers. Microstructure characteristics showed as follows:root vascular bundle was broad,and pericycle fiber bundles were found outside;stem vascular bundle had 8-25 cyclocytics,pericycle fibers were found outside, and the medulla was broad with myelinated fibers around;the upper and below epidermis of leaves had stomata and non-tentacle, and the main vein vascular of the leaf was collateral with vascula bundles upside and downside;the nonglandular hairs,starch grains,fibers,pollen grains,and tubes were shown in the powder of whole plant. Conclusion The above results are stable and reliable, and can be applied for pharmacognosy identification of Dichrocephala auriculata(Thunb.)Druce.

The chemical constituents of Leonurus heterophyllus were separated and purified by repeated column chromatography on silica gel, HPD 100, Sephadex LH-20, and PHPLC. Each compound was characterized by spectroscopic and physical data. Eight compounds have been purified and identified to be quercetin 3-O-robinobioside (1), rutin (2), isoquerci trin (3), hyperoside (4), quercetin (5), apigenin (6), genkwanin (7), and benzoic acid (8). Among them, compounds 2, 5-7 were isolated from L. heterophyllus for the first time; Compounds 1, 3, 4, 8 were obtained for the first time from the genus Leonurus. The in vitro activities against leukemia K562 Cells of pure components were evaluated by testing their IC50. Compounds 1-6, 8 exhibited in-vitro inhibitory activities against leukemia K562 cells in different extent.
Antineoplastic Agents ; chemistry ; isolation & purification ; pharmacology ; Cell Proliferation ; drug effects ; Drugs, Chinese Herbal ; chemistry ; isolation & purification ; pharmacology ; Humans ; K562 Cells ; Leonurus ; chemistry