Tehran University Medical Journal

Background: Bacillus cereus spores distribute widely in nature and can be isolated from different kinds of foods. This bacterium can produce diarrhea and emetic enterotoxins and syndromes. As infants are known to be more susceptible to B. cereus infection due to their incomplete intestinal flora and fast growth of this bacterium during consumption, it is very important to investigate the presence of B. cereus in infant formula and possible pathogenicity of this microorganism in infants. 

Methods: In this study, 60 samples of infant formula were examined for the presence of B. cereus. From a 1/10 dilution of each sample, a total amount of 1 ml was inoculated onto four phenol red agar plates containing mannitol, egg yolk emulsion and polymyxin B sulfate. The plates were incubated at 30°C for 24 hours. Confirmation tests were then performed on suspected colonies.

Results: Among the 60 samples, 11 samples had more than 10 cfu/g, four of which contained more than 102 cfu/g. The other 49 samples showed less than 10 cfu/g of B. cereus. 

Conclusions: We suggest that for infant formula the maximum microbial limit be reduced to less than 10 cfu/g to control B. cereus contamination and to prevent infection in infants. For this purpose, infant formula should be tested by the method and confirmation tests used in this study. In addition, susceptibility to penicillin, ß-hemolysis and growth rate at 45ºC could also be performed.

Background: Multiple Sclerosis (MS) is a neurodegenerative disease of the central nervous system (CNS). The hippocampus is a vital center for learning and memory it is extremely vulnerable to neurodegenerative diseases. The male hormones could be neuroprotective for the CNS. The current study is an attempt to investigate the effect of testosterone on learning and spatial memory following the demyelination of CA1 area by the injection of ethidium bromide in the rats' hippocampus. Methods: This experimental study has been conducted on healthy rats in the faculty of science of the Urmia University from September 2013 to February 2015. For demyelination in all previously gonadectomized healthy rats, 3µl ethidium bromide was injected into the CA1 area of rats by stereotaxic surgery. In addition, the treatment groups received 1µl testosterone (6µg/µl) during a 20-day timeframe on a daily basis after demyelination by the ethidium bromide. The control groups had no drug injection. The process of the learning and spatial memory of the rats were closely monitored by the radial Maze. The demyelination and remyelination in the hippocampus were checked by the myelin-specific coloring (Luxol fast blue and Cresyl violet). Results: The histological results suggest that the testosterone is capable of minimizing the destructive impacts of ethidium bromide in the treatment group as well as enhancing the remyelination process. In the group treated by testosterone, the percentage of the pyknotic cells 20 days after demyelination induction, represented a significant reduction compared to that of ethidium bromide group (P=0.008). The behavioral studies analyses show that the amount of the food finding time in those groups received ethidium bromide was significantly longer than those of the control groups (P=0.001). Furthermore, the application of the testosterone in the treatment groups reduced the extent of demyelination while the memory impairment induced by the ethidium bromide was significantly improved (P=0.001). Conclusion: Testosterone can act as a neuroprotective factor that reduces the extent of demyelination and the number of pyknotic cells. It also may improve the learning and memory impairment induced by ethidium bromide.