[Evaluation of lead acetate side effects on rat hippocampus and the effects of vitamin C on these]

To investigate the effect of ascorbic acid against lead-induced neurotoxicity in the rat hippocampus. The heads of 40 male Sprague-Dawley rats were divided into 4 groups: normal, control, lead-treated and lead plus ascorbic acid-treated. Lead acetate [20mg/kg] was administered intraperitonealy to rats for 7days in third and fourth groups. During this period, rats in the fourth group received 500 mg ascorbic acid, in drinking water daily. At the end of the treatment, all rats were sacrified and their hippocamps were excluded. Using TEM the samples were examined in terms of natural and apoptotic cells. Histopathological evaluation showed that apoptosis was attenuated significantly in the ascorbic acid group but not in the lead group. Simultaneous administration of ascorbic acid and lead increased the level of Bcl-2 and decreased Bax protein compared with lead-treated only. It seems that ascorbic acid may reduce the lead-induced toxicity in central nervous system

[Comparing lecture and problem-based learning methods in teaching limb anatomy to first year medical students]

Problem-based learning has replaced traditional teaching in most universities around the world but still there are many challenges in replacing traditional methods by this new method of learning. Two methods of lecture and problem-based learning [PBL] for teaching anatomy to junior medical students are compared in this study. Forty students of Artesh University of Medical Sciences, who entered university in 2005, were divided into two groups randomly. Groups were matched based on their Diploma average score, the raw score achieved in entrance exam, and the average score of their previous term. Then, limb anatomy was taught to both groups during two semesters, one group was taught through traditional method and the other through problem-based learning method. The headings of the lesson were the same for the two groups. Students were evaluated through a pre-test at the beginning of the semester and a post-test which was held at the end of the semester. Their viewpoints were also asked at the same time with post-test. Data was analyzed by SPSS software using independent T-test and paired T-test. Post-test scores in both groups were higher than the pre-test scores significantly. The mean difference for correct answers to judgment questions in post-test was higher significantly in PBL group compared with the traditional group. PBL group students were more satisfied with their teaching method. Students' viewpoints in PBL group concerning three domains of developing a sense of participation, encouraging students to study more and teacher's teaching abilities, earned higher scores compared to the traditional group. Students are encouraged to reflect more, and avoid memorizing the material in PBL method. Moreover, this method motivates students to study more by encouraging them into more group interaction

[Evaluation of neurotoxic effects of lead acetate on rat radial nerve]

Lead toxicity is a common popular problem. Many researches were performed about this toxicity both in-vivo and in-vitro since 100 years ago.Those studies showed that lead have toxic effects such as behavioral disorders, decrease of IQ and decrease of learning and memory. Also lead has neurotoxic effects such as decrease of neuronal density in visual cortex of monkey, cell death in hippocampus and decrease of acetylcolin in rat's hippocampus. In this study we examin neurotoxic effects of lead on rat's radial nerve because radial nerve is a mix nerve. 24 adult male rats were divided in six groups. Groups I and II received lead acetate 4% and 2%, groups III and IV received distilled water and normal water for one month. After this time, we killed rats and exposed radial nerve from behind of arm. Then studied them with light and electron microscopy. In experimental groups we saw decrease of myelin sheath diameter and decrease of nuclear density in schwann cell. Also we saw many granules in mitochondrial matrix, active macrophage, edema and disarrangement of myelin sheath layers. We suggest that lead neurophaty is due to schwann cell injury and this lesion lead to decrease of myelin sheath