Pentaquark baryons in SU(3) quark model

We study the SU(3) group structure of pentaquark baryons which are made of four quarks and one antiquark. The pentaquark baryons form {1}, {8}, {10}, {10}-bar, {27}, and {35} multiplets in SU(3) quark model. First, the flavor wave functions of all the pentaquark baryons are constructed in SU(3) quark model and then the flavor SU(3) symmetry relations for the interactions of the pentaquarks with three-quark baryons and pentaquark baryons are obtained.Comment: REVTeX, 36 pages, 8 figures, references added, section for mass sum rules is added, to appear in Phys. Rev.

The effect of study preparation on test anxiety and performance: a quasi-experimental study

Hasan Yusefzadeh,1 Jamileh Amirzadeh Iranagh,2 Bahram Nabilou31Department of Health Management and Economics, School of Public Health, Urmia University of Medical Science, Urmia, West Azerbaijan, Iran; 2Department of Public Health, School of Public Health, Urmia University of Medical Sciences, Urmia, Iran; 3Social determinants of health Research Center, Department of Health Management and Economics, School of Public Health, Urmia University of Medical Sciences, Urmia, IranBackground: Health care education is an important issue in the development of countries, and student’s academic achievement plays an important role in this respect. Test anxiety can affect the academic performance of students. This study aimed to investigate the effect of study preparation on test anxiety and performance of public health students.Methods: This quasi-experimental study investigated the effect of study preparation on reducing test anxiety and improving the performance of public health students at Urmia University of Medical Sciences, Urmia, Iran, in the academic year 2016–2017.All second- and third-year bachelor’s students in public health major were assigned into the intervention (n=20) and control groups (n=25). The assignment was based on the study preparation items and the defined benchmark.Data on general stress and test anxiety were collected by subjective self-assessment via paper-and-pencil surveys in the first week of the semester and before the final exam, respectively.Results: No significant difference was found in the level of general stress between the two groups at the beginning of the semester (p=0.55) based on the study preparation items. The level of test anxiety in the intervention group (47.90) was lower than in the control group (34.64) at the end of the semester (p=0.001). The mean value of exam scores was higher in the intervention group (p=0.015).Conclusions: The intervention reduced the level of test anxiety and improved the performance of students. Faculty members and heads of the departments should help students learn about the study preparation over the semester with engagement in learning-oriented approaches and class activities.Keywords: performance, education, anxiety, study preparation, Ira

Investigation of FLK-1 Gene Expression in Differentiated Mesenchymal Stem Cells, Exposed to Chemical, Mechanical and Chemical-mechanical Factors, in order to Study the Differentiation and its Stability

Background: Mesenchymal stem cells (MSCs) are multipotent cells, capable of differentiating into different cell lines.They can sense their surrounding biochemical and biophysical factors, which play major roles in their differentiation toward different phenotypes. Therefore, the exposure of these cells to endothelial growth factor (VEGF) as well as hemodynamic biomechanical forces, which act on endothelial cells in vivo, may direct MSCs toward vascular covering endothelial cells. The aim of this study, is to investigate the effects of chemical, mechanical and chemical-mechanical factors on the differentiation of mesenchymal stem cells and to examine the stability of this in vitro differentiation. Materials and Method: Human Subcutaneous adipose-derived mesenchymal stem cells were cultured in DMEM containing 20% FBS. They were characterized in passage 2, using flow cytometery technique and then were used in experiments. Mesenchymal stem cells were cultured in tubular silicone scaffolds, and then exposed to endothelial growth factor (VEGE), shear stress or combination of these two signals. In order to examine the differentiation, the expression level of FLK-1, as an endothelial specific gene, was studied. For studying the stability of this differentiation, FLK-1 mRNA levels were quantified using Real-Time PCR, upon completion of experiments, as well as on the 5thand 10th days after the tests. Results: According to the results of Real-Time PCR, immediately upon the completion of tests, mRNA level of FLK-1 was higher in the mechanical group (5.44), compared to the chemical (1.18) and chemical-mechanical (2.65) ones. On the 5th and 10th days after the experiments, FLK-1 expression levels were higher in chemical-mechanical group (6.34 and 7.56 respectively), compared to the chemical (2.18 and 0.99, respectively), and mechanical (2.96 and 3.92, respectively) ones. Conclusion: The findings of this study demonstrate that not only FLK-1 gene expression is stable over time, but also cells exposed to the chemical and mechanical cues, simultaneously, show the highest expression of this gene. The increase in FLK-1 expression over time implies the enhanced compatibility of differentiated cells with each other and their surrounding environment, which may be probably due to the higher sensitivity of FLK-1 gene expression to the combination of chemical and mechanical signals.   Keywords: Differentiation, Shear stress, Stem cell, Stability, VEGF

Effect of Purification of Human Adipose-derived Mesenchymal Stem Cells on the Expression of vWF Cell Factor Under Chemical and Mechanical Conditions

Introduction: Human adipose-derived mesenchymal stem cells (hADSCs) are easily accessible in the body, and under appropriate conditions, they can be directed toward various phenotypes. Therefore, hADSCs have been considered as a potential cell source for tissue engineering applications. hADSCs are able to differentiate into endothelial cells which covers the interior surface of vessels, in vivo. CD271 is a surface marker for hADSCs and hADSCs purified based on this marker (ADSCs-CD271+) are more capable of differentiating into various cells such as endothelial cells. In the present work, ADSCs-CD271+ were exposed to endothelial growth factor (VEGF) in vitro, and using a perfusion bioreactor, the effect of shear stress (a mechanical signal that is naturally produced by blood flowing ), on their differentiation into endothelial cells was investigated.       Materials and Method: hADSCs were isolated from fat tissue and cultured in DMEM containing 10% FBS. Then they were characterized in passage 2, using flow cytometery technique. CD271expression level was examined and flow cytometry using antibodies was used to separate ADSCs-CD271+ from (p2) ADSCs. ADSCs-CD271+ were cultured and characterized and their expression level was examined. ADSCs and ADSCs-CD271+ in passage 3 were infused into 2 mm-diameter-silicone tubes coated with collagen I. The four experimental groups included control group (cells exposed to DMEM + 10% FBS, for 7 days), chemical group (cells exposed to differentiation medium containing DMEM, 3% FBS and 50 ng/ml of VEGF, for 7 days), mechanical group (cells were in a designed perfusion bioreactor, under application of 4 dyn/cm2 of shear stress for 24 hours) as well as chemical- mechanical group. Real-Time PCR was used to quantify the expression level of vWF (the factor specifying endothelial cells) in the experimental groups. Results: in the current work, ADSCs showed 1% of CD271 marker, which was increased to 52% after purification. Evaluation of surface markers using flow cytometry confirmed the mesenchymal characteristics of both cell groups. According to the results from Real-time PCR, the chemical-mechanical group, the mechanical group and then the chemical group (in both purified and unpurified cells) showed the highest expression of vWF, respectively. The expression of vWF was generally higher in ADSCs-CD271+ groups compared ADSCs ones. Conclusion: The findings of this study imply that MSCs purification as well as combining the chemical and mechanical factors can improve vWF expression.   Keywords: Adipose-derived mesenchymal stem cell, CD271,Differentiation, VEGF, shear stress, vWF gene