To seek longitudinal changes in metacognitive processes through problem-based learning (PBL), we analysed the contents of all comments written reflectively by the third-year students after they finished discussions in each PBL session. After dividing their comments into meaningful units, we focused on two major thematic categories and five sub-categories to be analysed.
1) The number of units decreased significantly (chi-square: p=0.02).
2) Only the proportion of units categorised as “comprehension” in “individual learning” showed significant increase (Bonferroni: p<0.001).
3) Comments in this category stated that “I don't understand so-and-so.”
4) The increase of “comprehension” as they experienced more PBL suggested that students' knowledge of ignorance as metacognition was fostered through sessions in medical PBL.

OBJECTIVETo investigate the genes involved in pulmonary metastasis of human fibrosarcoma HT1080 cells in nude mice.

METHODSHT1080 cells were injected into the tail vein of BALB/ C nude mice. RNA samples were extracted from pulmonary metastatic tissues and normal control lung tissues, purified using Atlas Pure Total RNA labeling System (Clonetech Laboratories). cDNA probes labeled with 32P were prepared and hybridized to a cDNA membrane constructed with spots of 1176 human cancer related genes and radioactivities on the membrane were measeured by BAS 5000. The mRNA expression of gene FN1 was determined by real time RT-PCR using TaqMan methods. Furthermore, cells with FN1 expression were localized and obtained in situ in pulmonary metastatic foci by laser captured microdissection, and the FN1 expression was quantitated by real time RT-PCR.

RESULTSOf the total 1176 genes, 27 genes (2. 3%) revealed to be apparently up-regulated and 4 genes (0. 3% ) down-regulated. Real time RT-PCR analysis verified significant up-regulation of gene FN1. Laser captured microdissection/ real time RT-PCR analysis demonstrated up-regulated gene FN1 not in stroma cells but in tumor cell nests.

CONCLUSIONGene FN1 expression in fibrosarcoma HT1080 cells may be involved in pulmonary metastasis.

Animals ; Cell Line, Tumor ; Fibronectins ; genetics ; Fibrosarcoma ; genetics ; pathology ; Gene Expression Profiling ; Gene Expression Regulation, Neoplastic ; Humans ; Lung ; chemistry ; Lung Neoplasms ; genetics ; secondary ; Male ; Mice ; Mice, Inbred BALB C ; Mice, Nude ; Neoplasm Transplantation ; Oligonucleotide Array Sequence Analysis ; RNA, Messenger ; genetics ; metabolism ; RNA, Neoplasm ; genetics ; isolation & purification ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction ; Transplantation, Heterologous

OBJECTIVETo study the relationship between activation of pro-MMP-2 and expression of matrix metalloproteinases (MMP)-2, MT1-MMP and tissue inhibitor of metalloproteinases (TIMP)-2 mRNA in thymoma and thymic carcinoma; and to study the molecular mechanism of invasion and metastasis of thymic epithelial tumors.

METHODSFresh tissue specimens of thymoma, thymic carcinoma and normal thymus were included. The mRNA expression of MMP-2, MT1-MMP and TIMP-2 were analyzed by real-time reverse transcription polymerase chain reaction. The pro-MMP-2 activation ratio and its localization were determined by gelatin zymography and film in-situ gelatin-Zymography, respectively. Correlation of mRNA expression of MMP-2, MT1-MMP and TIMP-2 was investigated in tumors with different histological subtypes and clinical stages.

RESULTSThere were no significant differences in the expressions of MMP-2, MT1-MMP and TIMP-2 mRNA between I and II stage or III and IV stage thymomas (P > 0.05). However, significant differences of the expressions were observed between three tumor groups: I-II stage, III-IV stage and thymic carcinomas (P < 0.005), and between three histological subtypes: AB-B1 (lymphocyte-rich and mixed types), B2-B3 (cortical and predominantly polygonal cells types) and thymic carcinomas (P < 0.05). Expression levels of MT1-MMP and TIMP-2 mRNA were correlated with pro-MMP-2 activation ratio (Spearman rank correlation: r = 0.7235, r = 0.7647, P < 0.005). The expression of MMP-9 did not show significant differences between thymomas and thymic carcinomas.

CONCLUSIONSMMP-2, MT1-MMP and TIMP-2 mRNA expression levels are correlated with the histologic subtypes and clinical stages of thymoma. The mRNA expressions of MT1-MMP and TIMP-2 are correlated with the activation ratio of pro-MMP-2. It is speculated that upregulation of MT1-MMP gene expression may induce an activation of pro-MMP-2 through TIMP-2.

Adult ; Aged ; Aged, 80 and over ; Carcinoma, Squamous Cell ; enzymology ; metabolism ; pathology ; Enzyme Activation ; Female ; Humans ; Male ; Matrix Metalloproteinase 2 ; biosynthesis ; genetics ; Matrix Metalloproteinases ; biosynthesis ; genetics ; Matrix Metalloproteinases, Membrane-Associated ; Middle Aged ; Neoplasm Staging ; RNA, Messenger ; biosynthesis ; genetics ; Thymoma ; classification ; enzymology ; metabolism ; pathology ; Thymus Gland ; enzymology ; metabolism ; Thymus Neoplasms ; classification ; enzymology ; metabolism ; pathology ; Tissue Inhibitor of Metalloproteinase-2 ; biosynthesis ; genetics

Problem-based learning (PBL) tutorials were introduced at our university in April 2001. Because a complete PBLbased curriculum could not be adopted, a transitional curriculum incorporating 3-hour PBL tutorial sessions into the traditional curriculum was introduced. More than 80% of students agreed that PBL is an effective way of learning problem solving at the bedside. Twenty percent to 40% of teachers felt that students who took PBL were more motivated for bedside learning and self-directed learning and had better at presentation than were students who did not take PBL. Because of 80% of the curriculum comprised didactic lectures, most students considered PBL tutorials a type of lecture. For this reason, motivating students to learn additional material originating from PBL tutorials was difficult. Although the combination of a traditional curriculum and PBL tutorials may appear to be a new curriculum, this type of PBL has limited value as a method for studying problem solving.