فهرست مطالب عباس صاحبقدم لطفی

Organophosphorus compounds, are widely used as pesticides in agriculture. Organophosphate Hydrolase (OPH) enzyme hydrolyses a wide variety of organophosphate esters. In the present study, by using both enrichment culture and maximum dilution frequency techniques, the diazinon degradation bacteria was isolated from treated samples and was identified by morphological and biochemical tests. The enzyme was extracted from its bacterial strain and then purified using ammonium sulfate and ion exchange chromatography. The purity of the enzyme was confirmed by electrophoresis (SDS-PAGE), then its molecular weight was determined by specific marker proteins and its kinetic properties was evaluated.Using enrichment culture technique and the increasing factor of the biodegradability diazinon, enzymatic hydrolysis time decreased significantly with less than 10 hours. The main metabolite produced from diazinon hydrolysis was identified as 2-isopropyl-6-methyl-4-Hydroxy pyrimidine (IMHP, with less toxicity) through both thin layer chromatography (TLC) and spectrophotometry techniques. Purified OPH enzyme specific activity was found to be 57.48 fold of 16.44 U/mg of protein with a yield of 11.4 percent and approximate molecular weight of 40 KD. Maximum activity enzyme was at optimum pH 8.5 and temperature of 37 ͦ C. Substrate concentration up to 0.05 M and Co+2, Ca+2 metal ions had positive effects on activity enzyme. Michaelis constant (Km) and maximal velocity (Vmax) values were calculated as 434.2 μM and 107.3 μM/min, respectively. The results showed that OPH enzyme with its activity gradual and effective in addition to detoxification, could be played a key role in recovery of phosphate for the production of biofertilizer.

Using 3D culture to increase cell density and creating a suitable bedrock for the growth and proliferation and differentiation of stem cells is one of the important methods for their application in tissue engineering. In this study, mesenchymal stem cells of adipose tissue because of ease of access and abundance have been used to differentiate into hepatocyte-like cells to investigate the effect of 3D cultures on gelatin/laminin 3D scaffolds.

Mesenchymal stem cells were extracted from subcutaneous fat of the abdominal region of C57 mice by enzymatic digestion using collagenase enzyme. The extracted stem cells were confirmed by flow cytometry analysis and observation of the expression of specific stem cells markers such as CD105, CD44, and the absence of specific leukocyte (CD34) and hematopoietic (CD45). The non-toxicity of the scaffold was also investigated by the MTT method. Stem cells were cultured on a polystyrene surface and laminin and gelatin/laminin scaffold and treated with growth factors for 21 days in two stages. Cell differentiation was investigated by biochemical methods including examination of secretion indices such as urea and glycogen storage.

The expression of specific stem cells markers such as CD105, CD44, and the absence of CD34 and CD45 were proved. The ability to differentiate these cells into adipocytes and osteocytes has been proven.

The results show the presence of a three-dimensional gelatin/laminin scaffold increases the adhesion, proliferation, and differentiation of fatty mesenchymal cells to hepatocyte-like cells.

Stem cell therapy has been introduced as an innovative and promising treatment in Ischemic diseases. Mesenchymal stem cells are considered for cell therapy to some extent due to their immunemodulatory، differentiation potential، feasibility of isolation and proliferation properties. Stem cells، after transplantation، often encounter harsh and hypoxic environment in ischemic tissues، which leads to cell death and decreased therapeutic efficiency. On the other hand، the fate of stem cell viability and differentiation is still an ambiguous issue in cell therapy regenerative medicine. To overcome this problem، Hypoxic/Ischemic preconditioning has been reported as a powerful tool with beneficial effects on cell survival. The reported master regulator in this process is a transcription factor known as HIF-1α. This study aimed to over-express HIF-1α in mesenchymal stem cells along with eGFP by using lenti viral vectors. Bisistronic expression of eGFP and HIF-1α provides the possibilities of tracking the transplanted cells and mimicking the hypoxic conditions for genetically modified stem cells for future animal model studies.

Alpha (α)-actinins are located in the skeletal muscle Z-line and form actin–actin cross-links. It belongs to a highly conserved family of actin-binding proteins – the spectrin superfamily, which also contains the spectrins and dystrophin. Mammalian skeletal muscle has two isoforms:α-actinin-2 and α -actinin-3. However, the response of a-actinin to exercise training is little understood. Forty female Sprague-Dawley rats at the age of three months were obtained from Razi institute and assigned to a control(C; n=18) or exercise training (T; n=22) group. This study examined the effects of 8 weeks of resistance training on muscle mass and α -actinin-2 and α -actinin-3 levels in the flexor hallucis longus muscle(FHL). The resistance training consisted of climbing (with 1-RM until exhaustion) a ladder carrying a load suspended from the tail. The weights were increased gradually throughout the 8 weeks of training. Following 8 weeks of training, we observed significant increase in absolute muscle mass in FHL (P=0.01). Results show that no significant difference was found in α -actinin-2 and α -actinins 3 expression levels between C and T animals in response to progressive resistance training (P=0.61 and P=0.19 respectively). Surprisingly, protein expression levels of α -actinin-2 decreased 12% and α -actinin-3 increased 13% following 8 week of resistance training between groups, but it wasnt statistically significant. The results of this study demonstrate that progressive resistance training do not alters the expression level of α-actinins at the cellular levels in skeletal muscle and probably further investigations will indicate sarcomeric protein's response to exercise training.