Comparison the effectiveness of problem solving method with lecture-based method in the teaching of metabolic biochemistry

Introduction: The importance of biochemistry as a basic subject in biomedical sciences evokes its active learning through motivation of the students. This study aims to compare the effectiveness of , problem solving method with lecture-based method in the teaching of metabolic biochemistry. Method This study was done as a semi-experimental method among 43 nutrition undergraduate students of Isfahan university enrolled in metabolic biochemistry during the second semester at 2009 . After introducing the problem solving method to the students, they made their own group work to study and search about the presented , problem solving method subject (pentose phosphate pathway). A valid questionnaire completed by students was used to evaluate the usefulness and effectiveness of the applied method. The questions were divided in to 3 different fields consist motivation, interest and participating in group work. Student also took part in an exam including two types of questions related to traditional method and PBL. Data analysis was carried out by t-test and Q-square with SPSS software. Results The 83.7 percent of the students appreciated the value and necessity of biochemistry as one of the most important courses of their curriculum. The student's satisfaction of applying flexible educational methods for more effective and better learning is about 88.4%, as well as 66.7% for using , problem solving method. The mean and variance of motivation and interest, learning, and participation in group work were (66+16),( 68+16) and (70 +17), respectively. But any significant difference between student's exam scores in the traditional method and PBL was not seen. Conclusion The results show that implementations of , problem solving methods encourage students’ motivation and improve life-long and active acquired knowledge

The Role OF DNA Polymerases in Carcinogenesis

Background and Objectives: The major role of various types of DNA polymerases is genome replication. However, DNA polymerases are also necessary to establish the accuracy, efficiency of replication, repairing process, and consequently decrease in mutations induced by DNA-damaging agents. Cancer initiation is usually associated with induction of mutations in specific oncogenes or tumour suppressor genes by endogenous or exogenous genotoxic agents. Various point mutations occurring in cancer cells arise from error-generating activities of DNA polymerases. Published data show that decrease in the accuracy of DNA polymerases, without affecting their activity, could be the causative agents of tumors. It has also been reported in literature that the expression of DNA polymerases is altered in human cancers compared to normal tissue. In this review, we discuss some evidences of the role of various DNA polymerases in cancer development. The results of this study showed that lack of proper activity of DNA polymerases causes tumors through increase in the number of generated mutations in the genome. Attitude towards the function of these enzymes can result in new achievements for cancer prevention, diagnosis and treatment

Biochemical and Genetic Theories of Aging

Aging is the outcome of the progressive accumulation of different alterations in the body which accompanied with gradual decrease of the efficiencies of normal physiological functions and the capacity to maintain homeostasis that lead to the increase in disease probability and the death of people. The researchers have done different experiments especially on animal models for the perception of aging process, the longevity and the improvement of life quality. They have proposed more than 300 aging theories which overlap to some extent. In this article, we try to explain some of the most important theories with the emphasis on the epigenetic theory. The two most prominent biochemical theories of aging are free radical and mitochondrial theories. Normal aging is the result of the balance between damage and repair and these theories explain about the oxidative stress associated with the damages which result from reactive oxygen species (ROS), stress response signaling pathway and the antioxidant enzymes. According to the genetic theories, aging is the result of the controlled genetic program of the maturity and development. In addition, aging mitotic clock which guided by telomers, is important. The lengths of telomers which shorten after each cell division, can be regulated by many foods and telomeric epigenetic conditions. Furthermore, Aging influences not only by genes and mutations, but also by the environmental and epigenetic effects especially in the second half of life. The epigenetic changes include the alterations in gene expression without any changes in DNA sequences. Their biological and functional importance is accompanied with the loss of DNA global methylation, histone modification and gene promoter hypermethylation during aging process. To achieve to the dream of human for living healthier and longer, dietary manipulation with using the supplements and antioxidants, the understanding of a key role of the caloric restriction on longevity by the activity of Sirtuin proteins, the exercise and the perception of the environmental factors which affect epigenetic changes during aging process, are the most essential research issues in 21th century

The growth inhibitory effects of cadmium and copper on the MDA-MB468 human breast cancer cells

Background: Cadmium chloride is an important occupational and environmental pollutant. However, it can also be anti-carcinogenic under certain conditions. Copper, an essential trace element, has the ability to generate reactive oxygen species and induce cell apoptosis. This study was aimed to determine the growth inhibitory effects of cadmium and copper on the MDA-MB468 human breast cancer cells. Methods: By using MTT cell viability test, treatment of monolayer cell cultures with different metal concentrations (1-1000 μM) showed a significant dose dependent decrease (p < 0.05) of viable cells in different times. Results: A considerable cytotoxicity was observed for CdCl2 at 200 μM and 1 μM after 48 and 72 hours incubations, respectively. The highest concentration of CuCl2 (1000 μM) had little cytotoxic effects after 48 hours incubation period, but 1 μM of CuCl2 revealed a considerable cytotoxicity after 72 hours. The maximum synergic cytotoxic effect was observed at 0.5 μM of both metals. Conclusions: The results of the present study indicate that cytotoxic effect of CuCl2 is somehow lesser than that of CdCl2. This may be due to vital role of copper which is not known for cadmium so far

Comparison of SYBR Green and TaqMan methods in quantitative real-time polymerase chain reaction analysis of four adenosine receptor subtypes

Background: Real-time polymerase chain reaction (PCR) is based on the revolutionary method of PCR. This technique is the result of PCR enormous sensitivity and real-time monitoring combination. In quantitative gene expression analysis, two methods have more popularity, SYBR Green and TaqMan, SYBR Green is relatively cost benefit and easy to use and technically based on binding the fluorescent dye to double-stranded deoxyribonucleic acid (dsDNA) where TaqMan method has more expensive and based on dual labeled oligonucleotide and exonuclease activity of Taq polymerase enzyme. Specificity is the most important concern with the usage of any non-specific dsDNA-binding Dyes such as SYBR Green whiles more specificity showed by labeled oligonucleotide method such as TaqMan. In this study, we compared two common RT PCR methods, TaqMan and SYBR Green in measurement gene expression profile of adenosine receptors. Materials and Methods: Gene expression profiles of A1, A2A, A2B and A3 Adenosine receptors were analyzed by optimized TaqMan and SYBR Green quantitative RT PCR in breast cancer tissues. Primary expression data was normalizing by B. actin reference gene. Results: Efficiencies were calculated more than 95% for TaqMan and SYBR Green methods in all genes. The correlations between means of normalized data of each gene in two methods were positive and significant (P < 0.05). Conclusion: Data analysis showed that with the use of high performance primer and by use proper protocols and material we can make precise data by SYBR Green as TaqMan method. In other word by optimization of SYBR Green method, its performance and quality could be comparable to TaqMan method

Modification of strut effectiveness factor for reinforced concrete deep beams strengthened with CFRP laminates

This paper proposes a method to modify the strut effectiveness factor in the strut-and-tie model for CFRP-strengthened reinforced concrete deep beams. Two groups of deep beams comprising six ordinary reinforced concrete deep beams and six CFRP-strengthened reinforced concrete deep beams were experimentally tested under the four-point bending configuration. The shear span-to-effective depth ratio of the beams in each group was 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00. The theoretical principal tensile strain in CFRP-strengthened struts was modified based on a proposed empirical relationship, based on two ratios: the experimental to the theoretical value of principal tensile strain and the shear span-to-effective depth of deep beams

Optimization of Taq DNA polymerase enzyme expression in Escherichia coli

Background: In the present study, we optimized the experimental conditions using pET15b expression vector to obtain large amounts of Taq DNA polymerase. Materials and Methods: Correct framing of the gene in the expression vector pET15b and its orientation were analyzed by digestion and sequencing. Production of Taq DNA polymerase in Escherichia coli BL21 (DE3) cells was induced by incubation with different concentrations of IPTG. Optimum production occurred with the addition of 1mM IPTG for 2h. The activity of the obtained enzyme was measured by comparing the intensities of the produced DNA bands in PCR reactions. Results: Recombinant plasmid containing taq polymerase gene was confirmed by restriction digestion and DNA sequencing. Purified protein was identified by Western blotting. Optimum condition for the production of the enzyme was induction with 1mM IPTG for 23h. Addition of NP40 increased enzyme stability. Conclusion: We expressed the recombinant Taq DNA polymerase in E. coli using a T7based promoter system and obtained an active and stable enzyme