Browsing by All Authors "Seyhan, Nesrin"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
Item DNA damage in hair root cells as a biomarker for gamma rays exposure(Elsevier B.V, 2013-08-30) Tepe Çam, Semra; Seyhan, Nesrin; TAEK-SANAEMThe purpose of the present research is to examine whether human hair root cells can be used for dose assessment after in vitro exposure to ionizing radiation. Hair root samples plucked from random head regions were collected from 5 healthy human subjects. Some of these hair samples were used as control and some were irradiated with 0.5 - 5 Gy of gamma ray using a Cs-137 gamma irradiator at a dose rate of 0.14 Gy/sec. DNA damage (single strand break) were determined in hair root cells of these samples using the comet assay technique. The comet assay measurements, tail length (TL) and tail moment (TM) values showed that the irradiation significantly increased (p< .05) single-strand DNA breaks in hair roots cells of the exposed samples compared to control. A linear dose-effect relationship was observed when tail-moment or tail-length was plotted against the log of the radiation dose. This research suggests a possible usage of human hair root cells as a biomarker especially for low dose radiation exposure using the comet assay technique.Item Keratin içeren biyolojik örneklerin değişik tür ve enerjilerdeki radyasyon maruziyetinde dozimetre olarak kullanım potansiyellerinin araştırılması(Gazi Üniversitesi, Sağlık Bilimleri Enstitüsü, Biyofizik Ana Bilim Dalı, 2011-12) Tepe Çam, Semra; Seyhan, Nesrin; Korkmaz, Mustafa; TAEK-SANAEMItem Tea extracts protect normal lymphocytes but not leukemia cells from UV radiation-induced ROS production : An EPR spin trap study(Türk Biyofizik Derneği, 2014-09) Tepe Çam, Semra; Polat, Mustafa; Esmekaya, Meriç Arda; Canseven, Ayşe G.; Seyhan, Nesrin; TAEK-SANAEMPurpose: An ex vivo method for detection of free radicals and their neutralization by aqueous tea in human normal lymphocytes and MEC-1 leukemia cells under ultraviolet (UV) irradiation was investigated. Materials and Methods: This method is based on the electron paramagnetic resonance (EPR) spectroscopy spin-trapping technique. 5-tert-butoxycarbonyl 5-methyl-1-pyrroline N-oxide (BMPO) was used as the spin trap. Normal human lymphocytes and leukemia cells were exposed to UVB radiation (290 to 315 nm) at 47.7 and 159 mJ/cm2 and to UVA radiation (315 to 400 nm) at 53.7 J/cm2. Results: No significant radical production at 47.7 mJ/cm2 UVB dose in both cell lines was observed. In normal cells, free radical production was observed at 159 mJ/cm2 UVB and 53.7 J/cm2 UVA doses. However, both UV sources did not significantly produce free radicals in leukemia cells. A radical scavenging property of tea extracts (black, green, sage, rosehip) was observed in normal lymphocytes after both UVB and UVA exposure. In leukemia cells, the intensities of EPR signals produced in BMPO with tea extracts were found to be increased substantially after UVA exposure. Conclusion: These results showed that UV radiation induced free radical formation in normal human lymphocytes and indicated that tea extracts may be useful as photoprotective agents for them. On the other hand, tea extracts facilitated free radical production in leukemia cells.Item The use of human hair as biodosimeter(Elsevier Ltd., 2014-12) Tepe Çam, Semra; Polat, Mustafa; Seyhan, Nesrin; TAEK-SANAEMPurpose: To investigate the potential use of human hair samples as biologic dosimeter by electron spin resonance (ESR) spectroscopy. Subjects and methods: The hair samples were obtained from female volunteers and classified according to the colour, age and whether they are natural or dyed. Natural black, brown, red, blonde and dyed black hair samples were irradiated at low dose (5-50 Gy) and at high doses (75-750 Gy) by gamma source giving the dose rate of 0.25 Gy/s in The Sarayköy Establishment of Turkish Atomic Energy Authority. Results: While the peak heights and g-values (2.0021 -2.0023) determined from recorded spectra of hair were color dependent , the peak-to-peak line widths were varied according to natural or dyed hair (ΔHpp: 0.522- 0.744 mT).In all samples, the linear dose-response curves at low doses was going to saturate after ~ 300 Gy. In black hair samples taken from different individuals, the differences in the structure of the spectrum and signal intensities were not observed. The ESR signal intensities of samples stored at room temperature for 22 days fell to their half values in 44 hour in black hair, 41 hours in blonde and brown hairs, 35 hours in dyed black hair and in 17 hour in red hair. The activation energies of samples annealed at high temperatures for different period of time were correlated well with those obtained in the literature. Conclusions: The conditions in which hair samples can be used as a biological dosimeter were found. The dose