[Mesenchymal stem cells proliferation exposed to hypoxia]

Background and Objective: Some problems such as low viability and apoptosis after injection to the body because of exposure to toxic factors such as hypoxia, thermal stress, oxidative stress and food deprivation are encountered with stem cell application. It is suggested that preconditioning of the cells with cytotoxic factors before injection could enhance their efficiency. This study was done to determine the mesenchymal stem cell proliferation exposed to hypoxia by cobalt chloride

Methods: In this experimental study, Mesenchymal stem cells were isolated from rat bone marrow and cultured at least for four times. The cells were cultured in 96 well plates and treated with different concentration [0, 5, 10, 20, 50, 70, 90, 100, 120, 150 and 200 microM] of cobalt chloride for 6, 12, 24 and 46 hours. Cell proliferation was detected by MTT assay [3-[4,5-Dimethylthiazol-2-Yl]-2,5- Diphenyltetrazolium Bromide]

Results: The cells isolated from bone marrow were propagated easily in culture condition. The cells morphology was not altered after exposure to cobalt chloride. Preconditioning of mesenchymal stem cells with 120 microM for 6 hours, 20 microM for 12 and 24 hours and 5 microM for 48 hours significantly improved cell proliferation after hypoxia in cell culture [P<0.05]

Conclusion: Hypoxia preconditioning increases proliferation of mesenchymal stem cell

Survey of the time and order of eruption of permanent teeth of 4 to 14 years Torkman children in Gonbad Kavous City, 2003

Exfoliation of deciduous teeth and eruption of permanent teeth are an important stage for child's parent and dentist. The purposes of this study are: 1] to determine the mean and range of the times and sequence of eruption of permanent teeth in Turkman children, 2] to determine the relationship between eruption of permanent teeth with age and gender. In this analytical and cross-sectional study 1365 [681 boys and 684 girls] 4-14 years old Turkman children from schools of Gonbad Kavoos City were selected randomly and examined. If a tooth was observed in oral cavity, it meant eruption. The time and sequence of eruption was recorded in a questionnaire. The data were analyzed by SPSS software and t test analysis. The first erupted-teeth were lower central incisors and first molars in girls and last erupted-teeth were upper second molars in boys. The sequence of eruption in girls was in boys. Most of the lower permanent teeth erupted earlier than upper teeth; only for the first premolars in boys, earlier eruption in upper jaw [than lower jaw] was statistically significant. Only for upper canines in girls, difference between mean eruption times in two sides of jaws was statistically significant. Most of the permanent teeth erupted earlier in girls than boys; only for upper central incisors, earlier eruption in boys [than girls] was statistically significant. Permanent teeth in Turkman children erupt later than Lysell's and Hurme's standard tables. In Turkman children the median of eruption time in some teeth is more and in some teeth is less than Tehranian children and in some teeth is equal

[Production, formulation, quality control and primary biological studies of [18F]KF for skeletal PET scanning]

[[18]F]KF, considered as a reference standard for positron emission tomography of the skeletal system, was produced by the bombardment of enriched water [[18O]H2O>95%] with high energy protons in NRCAM cyclotron. After the extraction of fluoride from enriched water as KF, and passing it through microbial filter and fine adjustment of acidity and osmolality, it was converted into an injectable form. Pre-clinical investigations and biological controls were performed to determine radioisotope distribution in laboratory rats, thus suitable information was gathered for imaging in humans. This radiopharmaceutical was proved to be quite safe and of high quality as a result of testing in laboratory rats