Background & Objectives : This study was prepared to determine the frequency of Staphylococus aureus nasal colonization among intravenous drug abusers with respect to this fact that the rate of colonization is dependent on various factor including addiction behaviours. There wasn't any native study on this subject. The purpose of this study was to prepare the basic data of S.aureus nasal colonization among intervenous drug abusers, in order to reducing the incidence and nasal carriage rates of S.aureus infections.

  Methods : This was a prospective cross sectional study that included all of intravenous drug abusers who referred to three hospitals of Tehran from 2005 to 2006. Specimens for culture were obtained by swabbing anterior nares. Swabs were inoculated into nasal chapman broth and incubated at 35 °C for 48 hours. Isolated colonies were further subjected to identification and antimicrobial susceptibility testing. The related data were collected using patients` medical files and analyzed with using SPSS 11.

  Results : Staphylococcus aureus was grown i n 38 cultures (26.2%). We did not find any significant relationship between variables such as, economic condition, methods of using drugs, frequency of drug use, infection with different viruses, gender and colonization by Staphylococcus aureus.

  Conclusion: We observed lower nasal colonization with Staphylococcus aureus among patients. We suggest preparing similar study in order to clarify the role of different factors that have effect on the rate of nasal colonization with Staphylococcus aureus.

 Background & Objectives: Previous studies indicated that morphine consumption during pregnancy could inhibit embryos development. Present study further evaluated the effects of oral morphine consumption on the maternal and fetal portion placenta cells development in Wistar rats.

 Methods: Female Wistar rats (W: 170-200 g) were used in the present study. Morphine group were received morphine (0.05 mg/ml of tap water) after one night coupling with male rats for mating. On 14^th, 17^th days of pregnancy, the pregnant animals were killed with chloroform and the placentas and uterus were removed surgically and fixed in 10 % formalin. The fixed placentas and uterus were stained by H & E method and evaluated for their development. The thickness of layers, as well as number of the cells in both maternal and fetal parts of the placentas was determined by light microscopy and processed using MOTIC software.

 Results: The results indicated that oral consumption of morphine compared to control group, increased the thickness of the layers in maternal portion and also, increased the number of the cells in both maternal and fetal portion of the placenta.

 Conclusion: All together, oral morphine consumption may inhibit placenta cells development and disturb their natural functions. These abnormalities observed in the placenta by opioid addicted pregnancy Wistar rats.

  Background & objectives : Infertility is a global problem affecting millions of men and women in developed and developing countries. In this regard, in-vitro fertilization (IVF) plays an important role in improving the quality of life in infertile patients. However, studies have shown that the implantation failure in IVF is the main challenge of this procedure. Melatonin can increase the survival rate of embryos and IVF success rate through eliminating free radicals and removing reactive oxygen species. So, this study is conducted to investigate the effects of different concentrations of melatonin on the rate of newborns of mice following transfer oftwo-cell embryos .

  Methods : In this study, female mice with average age of six to eight weeks were superovulated by administering pregnant mares serum gonadotropin (PMSG) intraperitoneally (7.5 IU. ip), and followed after 48h by human chorionic gonadotropin (hCG) (7.5 IU. ip). Two-cell mouse embryos were obtained from female mice oviduct after 48 h. The embryos transferred bilaterally into pseudopregnant mice of the same strain through surgical procedure and 8-14 embryos were transferred to each tube. The study included 4 treatment groups and one control group (6 mice in each group). The treatment groups were exposed to subcutaneous injection of concentrations of 100 µm , 10 µm , 1 µm and 100 nm of melatonin. After the cesarean on 18^th day of pregnancy, the percentage of live births was assessed. The outcomes of the live birth rate were as­sessed using the chi-square test and statistical analyses were carried out using SPSS version 16.0. Percentage of live birth was calculated and compared with the control group.

  Results: A total of 701 two-cell mouse embryos were transferred into one control group and four experimental groups. The number and percentage of live births at concentrations of 100 µm and 10 µm of melatonin and the control groups were 21 (15.55%), 13 (9.15%) and 9 (6.47%), respectively. No infant was born at the concentrations of 1 µM and 100 nM of melatonin . The highest rate of live births was obtained at the concentration of 100 µM and showed a significant difference with the control group (p ≤ 0.01). There was no significant difference in live births at the concentration of 10 µm and control group.

  Conclusion : The results of this study indicated that subcutaneous injection of melatonin improves the two-cell mouse embryo growth and post implantation development of mice.

Background & objectives: Zinc as one of the most important trace elements is needed for proper functioning of the nervous system and homeostasis. Many studies show that stress causes memory impairment through various mechanisms, including oxidative stress induction and some mechanisms which are directly effecting brain function. So, in this work we assessed the effect of zinc chloride on passive avoidance memory and oxidative stress following acute stress in male rats.

Methods: In this study, 50 male Wistar rats were used in five groups: control, sham, stress, zinc chloride treatment and zinc chloride treatment before stress induction. For stress induction, rats were restrained (not immobilized) for 6 h/day, 7 days in a Plexiglas restrainer, and treated rats received an oral dose of zinc chloride 32 mg/kg/day by gavage for 6 days. At the end of the experiment, passive avoidance memory was avaluated by shuttle box and some oxidative damage markers were determined in all groups.

Results: Results of this study showed that animals which were exposed to stress showed a significant decrease in passive avoidance memory compared to control group (p<0.01) and the oxidative stress parameters in this group showed significant changes compared to the control group (p<0.05). While passive avoidance memory and oxidative stress parameters in group treated with zinc chloride were nearly closed to control group.

Conclusion: According to our results, zinc chloride with antioxidant properties can have a protective effect on memory impairment and oxidative stress induced by stress.