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Introduction: Streptolysin O (SLO) is an antigenic protein that is secreted by Streptococcus pyogenes. Streptococcal infections are diagnosed with anti streptolysin O. At present, streptolysin O is produced by vectors that have fusion protein. In this study streptolysin O without fusion protein vectors is produced. Materials and Methods: In this experimental study, Streptolysin O gene was amplified by Polymerase chain reaction (PCR) method and subcloned to prokaryotic expression vector pET28a. Escherichia coli BL21-DE3-plySs were transformed with pET28a-SLO and gene expression was induced by IPTG. Then it was purified by Ni-NTA kit. The concentration of SLO was assayed by Bradford method. To confirm recombinant SLO Western Blot was used. Results: The sequencing result was confirmed by Sanger method and was the same as SLO gene. Escherichia coli BL21 (DE3) pLysS was transformed with pET28a-SLO and gene expression was induced by IPTG. The expressed protein was purified by affinity chromatography with Ni-NTA resin. The concentration of purified protein was 100µg/ml. The integrity of product was confirmed by Western Blot analysis using a mouse anti streptolysin O. Conclusion: Data showed that recombinant SLO protein can be produced by pET28a in Escherichia coli. This protein maintains its antigenic effect very well. Therefore, recombinant SLO has same epitopes with natural form of this antigen.

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Background: Trauma noise is one of the major physical pollutants in modern societies. Sound conditioning, on the other hand, is known as one of the mechanisms for protecting the hearing system. Materials and Methods: In this experimental study, 15 three month-old male white New Zealand rabbits were divided into three groups. The equipments used in this study included a sound generator, a loudspeaker, an exposure box, a sound level meter, and a distortion product otoacoustic emission (DPOAE) device. The rabbits were assigned to trauma noise exposure, conditioning noise exposure, and control groups. The conditioning and traumatic sound levels were respectively 80 and 105dB within the 500-3000 Hz frequency. Results: Conditioning noise at the level of 80 in combination with trauma noise enhanced the rabbits hearing system tolerance up to 13-17 dB so that in all frequencies there were significant differences between the trauma noise exposure group and the sound conditioning and trauma noise conditioning group (P<0.05). Conclusion: Sound conditioning can act as an effective factor in protecting the hearing system against trauma noise.

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Background: Poly chlorinated biphenyls (PBCs) are the group of organic chemical materials that have a great chemical stability. These compounds are hazardous pollutants which pose various occupational and environmental problems. This study was conducted to determine the effect of microwave rays, hydrogen peroxide, Tio2 catalyst, and ethanol on the decomposition of PBCs. Materials and Methods: In this experimental study, a vessel reactor (250ml volume)that was connected with a tube connector to thecondensor system was used. A microwave oven with a fixed frequency of 2450 MHZ was used to provide microwave irradiation and ray powers used at 540, 720 and 900w. pH and temperature of the samples were continuously monitored and the experiments were repeated three times. Askarel oils were analyzed by GC-ECD. Results: The mean of total PCBS degradation at 540, 720, and 900w was 83.88±1.63, 89.27±2.44, and 95.98±0.81%, respectively. The mean of total PCBS degradation in terms of ratio to solvent with oil transformer in 1:1, 2:1, and 3:1 was 53.8±3.26, 79.04±1.24, and 95.08±1.69%, respectively. The mean of total PCBS degradation in terms of not using H2o2/Tio2 and using H2O2 (20%) and 0.05, 0.1, 0.15, and 0.2 g of Tio2 concurrently was 71.47±0.81, 87.9±2.16, 89.48±1.69, 91.7±1.24, and 93.07±3.09 %, respectively. Conclusion: Using microwave irradiation in the presence of H2O2 oxidant and Tio2 catalyst leads to the reduction of PCBS.