Browsing by All Authors "Polat, Mustafa"
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Item Effects of radiation on carbapenems : ESR identification and dosimetric features of gamma irradiated solid meropenem trihydrate(Taylor and Francis Ltd., 2006) Tepe Çam, Semra; Polat, Mustafa; Korkmaz, Mustafa; TAEK-SANAEMIn the present work, effects of gamma radiation on solid meropenem trihydrate (MPT), which is the active ingredient of carbapenem antibiotics, were investigated by electron spin resonance (ESR)spectroscopy.Irradiated MPT presents an ESR spectrum consisting of many resonance peaks.Heights measured with respect to the spectrum baseline of these resonance peaks were used to explore the evolutions of the radicalic species responsible for the experimental spectrum under different conditions. Variations of the denoted 11 peak heights with microwave power, sample temperature and applied radiation doses and decay of the involved radicalic species at room and at high temperatures were studied. On the basis of the results derived from these studies, a molecular model consisting of the presence of four different radicalic species was proposed, and spectroscopic parameters of these species were calculated through spectrum simulation calculations. The dosimetric potential of MPT was also explored and it was concluded that MPT presents the characteristics of normal and accidental dosimetric materials.Item Radiation sensitivity and dosimetric features of sultamicillin tosylate : an electron spin resonance study(Taylor & Francis, 2009) Tepe Çam, Semra; Polat, Mustafa; Korkmaz, Mustafa; TAEK-SANAEMParticular interest now centers on the preparation of steril-unit dose preparations. When preparations are purified from microorganisms using classic sterilization techniques, serious degradations may occur especially in temperature sensitive drugs and drug active components. Sultamicillin is the tosylate salt of double ester of sulbactam plus ampicillin. Sultamicillin tosylate (SULT) has previously been shown to be clinically and bacteriologically effective in a variety of infections. The use of high-energy radiation such as gamma rays for the sterilization of pharmaceuticals offers considerable interest because of the clear advantages this process has, compared to other methods of sterilization. However, radiosensitivity of irradiated pharmaceutical is important in this respect. Thus, radiosensitivity of SULT and its potential use as a dosimetric material were investigated by Electron Spin Resonance (ESR) spectroscopy in the present work. Samples of SULT powder were irradiated at doses of 3, 6, 10 and 15 kGy and ESR spectra were recorded at room and at different temperatures. Variations of different spectroscopic parameters with irradiation dose, temperature, and storage time were evaluated using data derived from experimental ESR spectra which exhibited five different resonance peaks. Stabilities of the radiolytic intermediates at high temperatures were also investigated through annealing studies performed at 340, 345 and 350 K. Rapid decrease in the resonance peak heights above 325 K was considered as a manifestation of unstable character of the radiolytical intermediates at high temperature although they decayed relatively slowly at room temperature. Seven different mathematical functions have been tried to fit experimental dose-response data and a power function of the applied dose was found to describe best the dose-response data.Item 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