Razi Journal of Medical Sciences

  Background : Epidemiological studies showed that low back pain after load-carrying and holding is the most common disorder in industrialized countries and cause of dysfunction and economic problems. Variable dynamic loads impose varying moments about the intervertebral joints and cause a threat to balance. The aim of the present study was to compare the postural stability while holding dynamic load among subjects with and without nonspecific low back pain.

  Methods: In this semi-experimental study 24 men (12 healthy and 12 low back pain ( participated. Subjects held static and dynamic loads in neutral and flexed trunk position (12 conditions). Center of pressure (COP) data were used to calculate: displacement, velocity and its standard deviation in Anterior- Posterior (AP) and Medial-Lateral (ML) directions, and path length.

  Results: The results of repeated measurements and independent T- tests showed that displacement of COP in ML direction in low back pain patients (1.31, 1.22 cm) during holding dynamic loads (10-15 Hz) is more than healthy subjects (1.03, 1.10 cm ). AP displacement, ML velocity and its standard deviation, path length, standard deviation of ML displacement in flexed and AP velocity in standing position during holding dynamic loads are more than static loads.

  Conclusion: The increased displacement of COP in subjects with low back pain during holding dynamic loads is probably due to higher sensory threshold in this patient. In addition, external perturbations in dynamic loads increase postural sway and may cause spinal injury.

Background: Dendrimers are a subset of branched structures that have certain structural order. The aim of this study was to investigate the performance of Nano Polyamidoamine–G5 (NPAMAM-G5)  dendrimers in removal of Escherichia Coli, Salmonella Typhi, Shigella Dysenteriae and Bacillus Subtilis from aqueous solution.

Material and methods: In this experimental study, initially dilution of 10³ CFU/ml were prepared from each strain of bacteria. Then different concentrations of dendrimers (0.025, 0.25, 2.5 and 25 µg/ml) in the ambient temperature (23-25° C) was added to water. In order to determine the efficiency of dendrimers in removal of bacteria, samples were taken at different times (0, 10, 20, 30, 50 and 60 min) and were cultured on nutrient agar medium. Samples were incubated for 24 hours at 37° C and then number of colonies were counted.

Results: Antibacterial properties of dendrimers in aqueous solution by increasing the dendrimer concentration and contact time, increased. At a concentration of 25 μg/ml and 60 minutes all kinds of bacteria except Shigella Dysenteriae (98% removal efficiency) 100% removal was observed. The concentration of 2.5 μg/ml at 60 minutes of bacteria, Escherichia Coli and Bacillus Subtilis,100% Were removed. All concentrations of dendrimer at different times were reduced bacteria.

Conclusion: Results of this study indicated that NPAMAM–G5 dendrimer is able to remove Escherichia Coli, Salmonella Typhi, Shigella Dysenteriae and Bacillus Subtilis in aqueous solution.