Objective:To evaluate the influence of examination as a transient stressful life event on the psychological status and occlusal function of college students.Methods:47 student volunteers(17 males,30 females;aged 19.30 ± 1.53 years) with normal occlusion were enrolled.SCL-90 questionnaire for evaluation of psychological status and surface electromyography for assessment of masseter and temporalis activities in maximum voluntary teeth clenching and in chewing different foods were performed at two stages (stage 1:one week before final academic examination;stage 2:one week after spring festival holiday).Results:Scores of questionnaire evaluation of psychological status showed obvious change in factors of somatization,interpersonal sensitivity,depression,anxiety and paranoid ideation(P ＜0.05).Paired t-test analysis of masticatory muscle function showed changes only in percentage overlapping coefficient(POC) of masseters in chewing carrot and activity index(AC) in chewing preserved haw jelly(P =0.014 and 0.018 respectively).However,other chewing status and indexes were not significantly changed.Conclusion:The psychological status of college students can be significantly impacted by examination stress without influence on masticatory activities.

BACKGROUND:Under co-culture conditions, mesenchymal stem cel s could regulate osteogenic differentiation and osteogenesis of osteoblasts. OBJECTIVE:To observe the osteogenic efficiency of osteoblastic precursor cel s co-cultured with undifferentiated bone marrow-derived mesenchymal stem cel s, umbilical cord-derived mesenchymal stem cel s, or placenta-derived mesenchymal stem cel s in mineralization medium. METHODS:Adipose-derived stem cel s were induced in osteogenic differentiation medium for 7 days before being indirectly co-cultured with undifferentiated mesenchymal stem cel s isolated from different tissues (bone marrow group, umbilical cord group and placenta group) in Transwel plates. Induced adipose-derived stem cel s cultured alone served as control group. At different experimental intervals, quantitative analysis of alkaline phosphatase activity and calcified matrix was preformed to observe the effects of mesenchymal stem cel s from different sources on the osteogenic efficiency of induced adipose-derived stem cel s. RESULTS AND CONCLUSION:Expression of alkaline phosphatase was significantly higher in different experimental groups than the control group (P<0.05), and it was also higher in the bone marrow group than the umbilical cord and placenta groups (P<0.05). Quantitative analysis of calcified matrix revealed that the experimental groups were significantly higher than the control group (P<0.05);and in experimental groups, the umbilical cord group was higher than bone marrow group and placenta group (P<0.05). These findings indicate that the osteogenic efficiency of induced adipose-derived stem cel s is improved dramatical y under co-culture conditions.

Objectives: To explore the critical values of temperature perception in various mucosa sites of oral cavity and to draw the perceptive temperature threshold maps in healthy volunteers. To observe the interrelationship between subjective cognitive perception and sympathetic skin response (SSR) under various levels of thermal stimuli. Methods: Forty-two healthy volunteers (recruited from the students of Tianjin Medical University, 16 females and 26 males) were enrolled in the present study. The whole oral mucosa of each subject was divided into multiple partitions according to the mucosa type as well as tooth position. Peltier patch (commodity name) semiconductor chip was placed in the central part of each subarea of the mucosa. The stimulus was increased or decreased at 1 ℃ each time from a baseline temperature of 37 ℃. Warm (WT) and cold (CT) perception thresholds were measured thereafter respectively. A topographic temperature map of the oral mucosa for each subject was drew. Furthermore, the SSR was elicited and recorded at three temperature levels of 50 ℃, 55 ℃, 60 ℃ respectively. Analog test with visual analogue scale (VAS) and McGill scales were also performed. Data were statistically analyzed with variance and generalized estimation equation. Results: The tip of the tongue was the most sensitive area with both WT [(38.8±2.1) ℃, P<0.05] and CT [(23.5±4.2) ℃, P<0.05]. The highest heat threshold of gingival mucosa was in the left lower posterior teeth area [(49.9±3.7) ℃, P<0.05], and the highest cold threshold of gingival mucosa was in the left upper posterior teeth area [(15.9±5.5) ℃, P<0.05]. The perceptive temperature threshold increased gradually from the midline to both left and right sides were observed symmetrically and bilaterally. There was no statistically significant differences in temperature perception threshold between males and females [WT, male (44.8±3.1) ℃, female (44.8±3.2) ℃, OR=1.100, P=0.930; CT, Male (18.4±4.9) ℃, female (20.8±4.8) ℃, OR=0.157, P=0.210]. The SSR amplitude at sites of the tongue tip and the lower lip were increased with the rise of temperature [tongue tip (4.58±4.04) mv, P<0.05, lower lip (2.89±3.01) mv, P<0.05]. However, SSR amplitude values had no significant differences between males and females [tongue tip, male (2.00±2.16) mv, female (1.89±1.20) mv, P=0.890; lower lip, male (0.94±0.82) mv, female (0.85±0.68) mv, P=0.887]. Nevertheless, the amplitude of SSR and the VAS score of subjects showed a similar trend. Conclusions The temperature perception levels were different amongst sites of lip, buccal mucosa, tongue dorsal mucosa and gingival mucosa. SSR amplitude values could reflect the responses of the mouth to the thermal stimuli.