Comparison of cell elasticity analysis methods based on atomic force microscopy indentation / 生物医学工程学杂志

In order to investigate in greater detail the two methods based on Hertz model for analyzing force-distance curve obtained by atomic force microscopy, we acquired the force-distance curves of Hela and MCF-7 cells by atomic force microscopy (AFM) indentation in this study. After the determination of contact point, Young's modulus in different indentation depth were calculated with two analysis methods of "two point" and "slope fitting". The results showed that the Young's modulus of Hela cell was higher than that of MCF-7 cell,which is in accordance with the F-actin distribution of the two types of cell. We found that the Young's modulus of the cells was decreased with increasing indentation depth and the curve trends by "slope fitting". This indicated that the "slope fitting" method could reduce the error caused by the miscalculation of contact point. The purpose of this study was to provide a guidance for researcher to choose an appropriate method for analyzing AFM indentation force-distance curve.

Relationship of feeding behavior with nourishing and developing status of infants / 中国组织工程研究

BACKGROUND: There are less researches on the relationship of parents'feeding behavior with nourishing and developing status of infants.OBJECTIVE: To study the relationship between the parents' feeding behavior and the nourishing and developing status of infants.DESIGN: A cross-sectional study.SETTING: Center of Maternal and Children' s Health,the First Hospital of Xi'an Jiaotong University.PARTICIPANTS: The study was carried out during January to December in 2002,at the Center of Maternal and Children' s Health,The First Hospital of Xi'an Jiaotong University. A total of 346 infants,aged 0 to 18 months old,were selected from the Fuping county and Chengcheng county of Weinan area by using the stratified duster sampline method. Inclusive criteria: infants with the gestation period between 37 to 42 weeks,without obvious diseases,no congenital abnormality; Exclusive criteria: infants with congenital disease or abnormality. Totally 324 infants,who were in accordance with the above criteria,were divided into 5 groups according to their month age.METHODS: The nursing persons of the infants were called at their houses,and the self-designed "Investigation Tables on Infant's Nutrition"were filled out.MAIN OUTCOME MEASURES: ① Status of slight malnutrition of infants of different month ages; ② Status of nutrition and development of infants,within 4 months, with different feeding behaviors; ③ Effects of beginning time,quality and frequency of complementary food on the nourishing and developing status of infants.RESULTS: In the first 4 months after birth,the rate of breast-feeding was high and the nourishing status of the infants was good. But the nourishing and developing status of infants became comparatively worse after 4 months age,because of inappropriate complementary food. As compared the slight malnutrition infants with normal infants,there were significant differences in the beginning time and kinds of complementary food(P<0.01).CONCLUSION: There is close relationship of the feeding behaviors with the nourishing and developing status of the infants.