[Evaluation of submicron particle filtration efficiency of domestic and imported surgical masks]

Bioaerosols are one of the most important agents that cause post operating infections in hospitals. Surgical masks are recommended for prevention of bioaerosols transmition in operating rooms. This study aimed at evaluation of submicron particle filtration efficiency of domestic and imported surgical masks. In this cross sectional study, 5 types of surgical masks that have the most utilization in operating rooms of country's hospitals including domestic and imported surgical masks were tested. To evaluate all samples, the submicron particle filtration measurements were carried out based on ISIRI 6138 and American DOP standards. Filtration efficiency calculations and pressure drop measurements were performed and the results were analyzed using statistical tests. Results showed that particle filtration efficiency of domestic and imported masks were 56.130% [ +/- 10.7] and 31.906% [ +/- 7.062] respectively. Also, filtration efficiency in domestic masks were more than imported masks [P< 0.001]. Among all samples, Arman mask had the most filtration efficiency [66.5475% +/- 6.14951], where the least [27.8275% +/- 4.44152] filtration efficiency [P< 0.001] belongs to Blosom. The maximum mean of pressure drop in Arman mask [35 +/- 2. 58 Pa] and the least mean of pressure drop in Zist filter mask [11 +/- 1.82 Pa] were observed. According to the effect of filtration efficiency and pressure drop on general quality of mask, the quality factor of masks were also evaluated. Results showed that Zist filter mask had the most quality factor [0.068] while Blosom had the least quality factor [0.016]. This research showed that domestic surgical masks have a better quality toward imported surgical masks but can not obtained quality confirmed by standards, yet. To reduce respective infections and prevalence of diseases, it is recommended using filters with suitable physical characteristics and also carrying out test of surgical masks before supplying

study of effectiveness of blended learning approach for medical training courses

Blended learning as a method of learning that includes face to face learning, pure E-learning and didactic learning. This study aims to investigate the efficacy of medical education by this approach. This interventional study was performed in 130 students at different clinical levels participating in class sessions on [congenital adrenal hyperplasia and ambiguous genitalia]. Sampling was done gradually during 6 months and all of them filled a pretest questionnaire and received an educational compact disk. One week later, a presence class session was held in a question and answer and problem solving method. Two to four weeks later, they filled a posttest questionnaire. There was a significant correlation between pretest and posttest scores and the posttest scores were significantly more than the pretest ones. Sub-specialized residents had the most and the students had the least attitude towards blended learning approach. There was a significant correlation between the research samples' accessibility to computer and their attitude and satisfaction to blended learning approach. Findings generally showed that the blended learning was an effective approach in making a profound learning of academic subjects

[ effect of guidance channel on sciatic nerve repair in adult rats]

Peripheral nerve lesions are a challenge for neurosurgeons and different surgical repairing methods are applied for the treatment of this problem. This study was conducted to evaluate the poled polyvinelidene fluoride [PVDF] tube filled with nerve growth factor [NGF] and collagen gel as a substitute for nerve autograft. In this experimental study the left sciatic nerve was manipulated in 50 male Wistar rats and then the animals were divided randomly into five groups. In the epineural group the injured nerves were repaired by end to end suture. In the rats with autograft a 10 mm piece of sciatic nerve was rotated through 180 and sutured in the nerve gap. In the nerve guidance channel group [NGC], polarized piezoelectric PVDF tube containing NGF and collagen gel was replaced in the gap and in the axotomy group two nerve ends were hidden among muscles. The left sciatic nerve was exposed but not transected in the sham group. After two months L4-L6 segment neurons of spinal cord were studied histologically and by immunohistochemical and axonal DiI tracing. The collected data were analyzed by one way ANOVA, LSD and paired t-test. The mean number of Bax positive cells and labeled motor neurons increased significantly in axotomy and sham group respectively, compared to the other groups [P<0.05]. Also, the mean number of labeled motor neurons increased significantly in epinural group in comparison to the autograft and the NGC groups [P<0.05]. There was no significant difference in the mean number of the labeled neurons between the autograft and nerve guidance channel groups. The mean number of motor neurons in the left side showed a significant decrease in comparison to that of the right side [p<0.01]. The PVDF tube together with other therapies provided a favorable environment for nerve regeneration and could be used as a substitute for autograft in nerve injuries

[Structural and ultrastructural study of motor neurons following sciatic nerve repair by epineural suture, autograft and nerve guidance channel in adult rat]

Much interest has been focused on the development of alternative instrument for bridging the nerve gaps. In the present study we used poled polyvinelidene fluoride [PVDF] tube filled with nerve growth factor [NGF] and collagen gel as a substitute for nerve autograft and compared the results with other current surgical techniques. In this experimental study, 40 male Wistar rats each weighing 200-250 g were randomly divided in five groups; nerve guidance channel, autograft, epineural suture, axotomy and sham operation. In nerve guidance channel groups, a 10 mm piece of left sciatic nerve was transected and this gap was repaired by PVDF tube containing NGF 7s [100 ng] and collagen gel [1.28 mg/ml]. In autograft group, the 10 mm piece was 180° rotated and sutured to two nerve ends. In epineural suture group, left sciatic nerve in the middle thigh was transected then sutured end to end. In axotomy group, left sciatic nerve was transected in the middle thigh and was not repaired. After two months, left ventral L4-6 segments of spinal cord were removed and semi-thin and ultra-thin preparation for light and electron microscope were done. Contra-lateral side of spinal cord segments was used as control in all groups. After two months we observed motor neuron atrophy and shrinkage, cytoplasmic vacoules and piknotic neurons in different surgical groups, but it was more intense in axotomy group. These changes were less in epineural suture group than in autograft and nerve guidance channel groups. In sham and control groups no changes were observed. In addition, increased nuclear condensation, nuclear membrane folding, central and marginal chromatin clumping in spinal motor neuron were observed in surgical groups mainly in axotomy group. According to the results, any type of injury to the sciatic nerve can cause cell changes and finally cell death in the spinal motor neurons. Using PVDF with NGF and collagen gel reduced cell changes at the level of autograft

[Sensorineural hearing loss in pseudoexfoliation syndrome]

To determine hearing thresholds at sound frequencies important for speech comprehension in subjects with ocular pseudoexfoliation [PXF] and to compare them with that of controls without PXF. Eighty-three subjects with ocular PXF and 83 age and sex matched controls without PXF were enrolled in this case-control study. Pure tone audiometry [bone conduction] was performed at 1, 2 and 3 kilohertz [KHz] in all subjects. Thresholds were compared to an age and sex stratified standard [ISO7029] and between study groups. Hearing loss was defined as sum of tested hearing thresholds [HTL-1, 2, 3] lower than the ISO7029 standard median. The study included 60 male and 23 female subjects in each group. Hearing loss was present in 147 of 166 [88.6%] examined ears in the case group vs 89 of 166 [53.6%] ears in the control group [P<0.001; odds ratio [OR] = 6.69; 95% confidence interval [CI], 3.49-11.79]. Overall 78 subjects [94.0%] in the case group vs 58 subjects [69.9%] in the control group had hearing loss in one or both ears [P< 0.001; OR=6.72; 95%CI, 2.42-18.62]. Hearing thresholds at each of the examined frequencies and the HTL-1, 2, 3 were also significantly higher in individuals with PXF. Although glaucoma was significantly more common in subjects with PXF [51.8% vs 22.9%, P<0.001], it was not associated with hearing loss in any of the study groups. Hearing thresholds at frequencies which are important for speech comprehension are significantly worse in individuals with ocular PXF as compared to matched controls. This finding may support the multi-organ nature of PXF syndrome