The abilities of self-study,thinking and communication are much more emphasized in the problem based learning(PBL)than in the conventional curriculum.From the view of the inherent relationship between the ability training and PBL,this paper probes into the characteristics of PBL to find the way of fitting the situation of our country.It is essential to the successful teaching and training more high quality students.

Objective To study the correlation between structure of b D -glucan derivatives from Poria cocos sclerotiuma and anti gastric cancer activities of elderly rats.Methods A water insoluble (1→3)-β-D-glucan (PCS3-Ⅱ ) isolated from fresh sclerotium of Poria cocos was sulfated,carboxymethylated,methylated,hydroxyethylated and hydroxypropylated,respectively,to prepare five water-soluble derivatives.Their activities of the native β-glucan and five derivatives against gastric cancer cell strains of MKN-45,SGC 7901and MKN-28 were tested in vitro and in vivo.Results The native β-glucan did not show any anti-gastric cancer activity,while the sulfated and carboxymethylated derivatives significantly exhibited the anti gastric cancer activity against MKN-45,SGC-7901 and MKN-28 cells in vitro,and elderly rats with MKN-45 transplanted tumor,especially.The gastric cancer inhibition rates of elderly rats were 32.7％ and 36.4％ for the 100 mg/kg sulfated and carboxymethylated derivatives,respectively.Conclusions The fresh sclerotium of Poria cocos polysaccharides can not show any anti gastric cancer activity in vitro,but the sulfated and carboxymethylated derivatives may increase the inhibition effect.Water-solubility,higher chain stiffness and relatively molecular weight would be benefit to increase anti-elderly gastric cancer activity of polysaccharides from Poria cocos sclerotiuma.

BACKGROUND: There are plenty of studies of estrogen effects on mammalian osteoblast, but the studies of estrogen effects on bird osteoblast cannot be found. There are many reports about the side effects of letrozole on bone metabolism, but there are no reports about the effect of letrozole on osteoblast.OBJECTIVE: The effects of estrogen and letrozole on the proliferation, cell cycle, estrogen receptor mRNA expression and alkaline phosphatase (ALP) activity of chicken osteoblast in vitro were studied in order to illustrate the mechanism of medullary bone osteogenesis.METHODS: The osteoblasts were harvested from the frontal bone of 15-day SPF chicken embryos by the enzyme digestion, and treated with various mass concentrations of estrogen (0, 5, 10, 20, 100. 200, 400,800, 2 000, 20 000 ng/L) and letrozole (0, 5.10, 25, 50, 100, 250, 500, 1 000, 5 000 μg/L). The proliferation rates of the osteoblast treated with estrogen or letrozole were measured through the MTT method, The ALP activities of osteoblast were measured by the pNPP method. The cell cycle was measured by flow cytometry. The expression of estrogen receptor mRNA was detected using real-time fluorescent quantitative polymerase chain reaction (PCR).RESULTS AND CONCLUSION: The estrogen could promote proliferation of osteoblast in concentration- and time-dependent fashion. Estrogen could increase the expression of estrogen receptor mRNA, impulse cell cycle, and elevate ALP activities.Letrozole could increase the cell population, impulse cell cycle, inhibit estrogen receptor mRNA expression, but letrozole has no effects on ALP synthesis and secretion.

AIM: To investigate the regulatory effects of lipopolysaccharide binding protein(LBP)on activation of p38 signaling pathway induced by lipopolysaccharide(LPS)in alveolar macrophages. METHODS: The LBP from actue phase rat serum was purified by ammonium sulphate precipitation, Bio-Rex70 resin and the MonoQ column. Rat alveolar macrophages were exposed to LPS (0 01 mg/L or 1 mg/L) the various concentrations of LBP(0 mg/L, 0 01 mg/L, 0 1 mg/L,1 mg/L and 10 mg/L) Western blotting were used to detect phospho-p38 in alveolar macrophages RESULTS: SDS-PAGE analysis indicated that the purified preparation of rat LBP showed homogeneity and the molecular weight was 60 kD.The binding of lipopolysaccharide to mononuclear cells were enhanced by purified rat LBP. Stimulation of rat alveolar macrophages with LPS at concentration of 0.01 mg/L was LBP dependent. LBP at concentrations up to 1 mg/L was able to increase the activation of p38. However , when LBP concentrations were further increased to 10 mg/L, the phosphorylation levers of p38 were lower as compared with that in the presence of 1 mg/L. Stimulation of rat alveolar macrophages with LPS at concentrations of 1 mg/L was LBP-independent. CONCLUSION: The activation of p38 induced by LPS at lower concentration(0.01 mg/L ) was LBP-dependent, meanwhile, LPS at higher concentration (1 mg/L ) was LBP-independent.

Objective To report a familial dentinogenesis imperfecta type Ⅱ (DGI type Ⅱ) with a novel splicing mutation in DSPP (dentin sialophosphoprotein) gene.Methods Based on the result of linkage analysis performed previously to map the candidate gene DSPP in the family, the promoter,the first four exons and exon-intron boundaries of DSPP were directly sequenced for the members of the DGI type Ⅱ family. Denaturing high performance liquid chromatography (DHPLC) analysis was performed to confirm the results of sequencing.Results A novel splicing mutation of 23 bp deletion in intron 2 of DSPP gene was identified by DNA sequence analysis. The mutation changed acceptor site sequence from CAG to AAG, and might result in functional abolition of possible branch point site in intron 2. DHPLC result was consistent with that of sequencing. The mutation may be identified in all affected individuals, but not found in normal members of the family and 50 controls.Conclusion These results suggest the deleted mutation of DSPP gene causes DGI type Ⅱ in the family. The mutation has not been reported before.

Objective:To investigate the expression of annexin 5 in rat testis after removing submandibular gland in rats. Methods:On day 14,28 and 42 after the operation,the changes of annexin 5 expression in rat testis were analyzed by Western blot and Immunohistochemistry.Results:Western blot showed that there was a 27.5% and a 35.2% significant increase(P

Background and purpose:Rabs are members of Ras-related small GTPase superfamily. Rab27A is a unique member in the Rab family and has specific implications in human genetic diseases. We studied the potential role of Rab27A in proliferation, distribution of cell cycle, apoptosis and invasion of breast cancer cells and its mechanism(s). Methods:The eukaryotic expression vector containing Rab27A open reading frame (ORF) pcDNA3.1(+) - Rab27A was constructed and transfected into MDA-MB-231 breast cancer cells. Then we detected the changes in terms of cell growth, cell cycle distribution, apoptosis and in vitro invasion capability before and after transfection. We also applied RT-PCR to investigate the molecular basis.Results:① The expression of Rab27A was increased as invasive and metastatic ability increased in four human breast cancer cell lines. ② Overexpression of Rab27A can promote breast cancer cells to grow faster, increase the proportion of S phase cells, avoid apoptosis and invade in vitro. ③ Rab27A transfectants constitutively enhanced the expression of Cyclin D1, MMP-7 and MMP-9 in MDA-MB-231 cell lines, on the contrary, that of p16 were down-regulated constitutively. Reduced Rab27A expression by RNAi down-regulated the expression of Cyclin D1, MMP-7 and MMP-9, and up-regulated p16 expression.Conclusions:Rab27A can stimulate breast cancer cells to proliferate, increase the proportion of cells in S phase,avoid apoptosis and invade in vitro by regulating the expression of Cyclin D1, MMP-7, MMP-9 and p16.

Objective:To explore the relationship between constitutional types of Chinese medicine and Alzheimer's disease (AD) and to construct an early warning model for AD risk.Methods:In the established multimodal interventions to delay dementia and disability in rural China (MIND-China) study, 4 033 elderly subjects aged ≥60 years old were included. The data including demographic, underlying disease and neuropsychological data were collected.The Chinese medicine service record form for the elderly was used to assess constitutional types of Chinese medicine and to apply the NIA-AA diagnostic criteria published by the National Institute on Aging and the Alzheimer's Association in 2011 for the diagnosis of clinically likely AD. Logistic regression analysis and AD risk prediction models were constructed using R statistical software, and the final prediction results were presented using columnar plots.Results:The MIND-China cohort was dominated by the abnormal constitution (69.28%), of which Phlegm-wetness type was the most common (58.05%), followed by Yang-deficiency type (23.85%). The most constitutional type of Chinese medicine among AD patients was Phlegm-wetness type (54.35%), followed by Qi-depression type (38.04%). Multi-factorial logistic regression analysis suggested that increasing age ( β=0.101, P<0.001, OR=1.107, 95% CI=1.069-1.146) and Qi-depression type ( β=0.622, P=0.016, OR=1.862, 95% CI=1.116-3.076) were able to increase the risk of developing AD, while education ( β=-1.047, P<0.001, OR=0.351, 95% CI=0.205-0.584) was able to reduce the risk of developing AD. By using the risk score model to calculate the total risk score for each subject and plotting the receiver operating characteristic curve (ROC), the area under the ROC was 0.769 and the calibration curve showed excellent consistency between prediction and reality. Conclusion:Older adults with Qi-depression type are significantly associated with an increased likelihood of AD.

Alzheimer disease(AD)is a common neurodegenerative disease characterized by cognitive decline and is the most common cause of dementia in the elderly.At present,the pathogenesis of AD remains unclear,and there is still a lack of effective treatment methods for etiologies.Apolipoprotein E(APOE)is currently the only risk gene recog-nized for AD,and the ApoE protein encoded by ApoE plays an important role in the pathological processes of AD,such as amyloid β-protein deposition,excessive phosphorylation of tau protein,and neuroinflammatory reaction.This article re-views the structure and function of ApoE and its role in the pathological processes of AD,in order to provide ideas and di-rections for finding new intervention targets for AD.

Objective:To investigate the relationship between lifestyle factors and stroke in the elderly.Methods:Data were obtained from a natural cohort of the Multimodal Intervention to Delay Dementia and Disability in Rural China(MIND-China)study.A total of 5 009 participants aged 60 years and above were enrolled, of whom 954(19.05%)had experienced a stroke.Logistic regression analyses were conducted to assess the association between five lifestyle factors(smoking, drinking, physical exercise, social activity and sleep quality)and the incidence of stroke.Results:In model 1, after adjusting for age, sex and education, only social activity( OR=0.783, 95% CI: 0.668-0.917)and good sleep quality( OR=0.731, 95% CI: 0.621-0.860)emerged as protective factors against stroke(both P<0.05).No statistically significant associations were found between other lifestyle factors and stroke.Analysis of a variety of healthy lifestyle practice combinations showed that having 3( OR=0.639, 95% CI: 0.433-0.944), 4( OR=0.620, 95% CI: 0.409-0.941)and 5( OR=0.397, 95% CI: 0.197-0.799)healthy lifestyle practices were protective factors against stroke(all P<0.05).In model 2, after adjusting for age, sex, education, body mass index, diabetes, hyperlipidemia, hypertension, and the APOE genotype, the results were consistent with those of Model 1. Conclusions:Lifestyle factors are significantly associated with the risk of stroke in the elderly population.The healthier lifestyle practices are adopted, the lower the risk of stroke will be.