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Karmakar, P. C.,Cho, Y. J.,Kim, Y. H.,Jung, S. E.,Jin, J. H.,Kim, B. J.,Kwon, W. S.,Kim, Y. H.,Pang, M. G.,Ryu, B. Y. ACADEMIC PRESS 2018 TOXICOLOGICAL SCIENCES Vol.164 No.2
<P>Many of the testicular cancer-survived patients, treated with chemotherapeutic drugs, show infertility, pre and postimplantation loss, and germ cell abnormality. Studies examining the negative effects of chemotherapeutic drugs on testicular germ cells are ongoing; however, information on the stemness properties and proteomic profiles of these cells are lacking. This study investigated the effects of chemotherapeutic drugs etoposide, cisplatin, bleomycin, and their combination (BEP) on the physiology and stem cell activity of mouse germ cells in vitro. Our results showed that treatment with the abovementioned drugs affected germ cell viability and decreased the number of proliferating germ cells significantly at specific concentrations (0.05 mu M etoposide, 1 mu M cisplatin, 10 mu M bleomycin, and 0.1 mu M BEP), which maintained a survival rate of >90%. We also observed a significantly higher percentage of apoptotic cells and alterations in the expression of undifferentiated and differentiated spermatogonia-related genes and marker proteins in germ cells exposed to abovementioned concentrations of the drugs. Next, we performed germ cell transplantation into recipient mice and observed a remarkable reduction in stemness properties of spermatogonial stem cells at these concentrations. Based on these results, we assessed the levels of differentially expressed proteins by performing proteomic analysis. We found that treatment with the abovementioned drugs induced cell damage, oxidative stress, metabolic disruption, and immune deficiency which may promote tumor regeneration, cytotoxicity, infertility, and transgenerational cellular function transmission. Thus, this study provides information about the chemotherapy-induced recurrent destruction and thereby can lead possible changes in medication.</P>
EFFECT OF Mn DOPING ON MICROSTRUCTURE AND OPTICAL PROPERTIES OF NANOCRYSTALLINE ZnO
M. KARMAKAR,O. MONDAL,B. ROY,P. K. PAUL,M. PAL 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.6
Mn-doped ZnO has emerged as the most studied system for prototype applications in spintronics devices because of its interesting magnetic properties. In this report, nanocrystalline ZnO doped with various concentration of Mn have been synthesized from different precursors using modified ceramic route. Samples are characterized by using X-ray diffractometer (XRD), high resolution transmission electron microscopy (HRTEM) and UV-Vis spectrophotometer. XRD and HRTEM studies confirm the growth of single phase, well crystallized Mn-doped ZnO nanoparticles. Particle size estimated from Rietveld analysis as well as TEM images show a decreasing tendency with the increase in Mn concentration. We observe both band bowing and red shift in optical bandgap by varying the concentration of Mn and precursors. This study demonstrates that Mn concentration is not the only factor but precursors have a definite role on the variation of optical bandgap.
Mn SUBSTITUTION EFFECTS AND ASSOCIATED DEFECTS IN ZnO NANOPARTICLES STUDIED BY POSITRON ANNIHILATION
B. ROY,B. KARMAKAR,P. M. G. NAMBISSAN,M. PAL 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2011 NANO Vol.6 No.2
Nanocrystalline ZnO particles substituted with different concentrations (0–30%) of Mn were synthesized by using a modified ceramic route and characterized by X-ray diffraction, transmission electron microscopy, selected area electron diffraction and energy dispersive X-ray analysis methods. Positron lifetime and coincidence Doppler broadening measurements were used as probes to identify the vacancy-type defects present in them and monitor the changes while doping. The predominant positron trapping center in the undoped ZnO is identified as the trivacancy-type cluster V_(Zn+O+Zn), which is negatively charged, and it transformed to the neutral divacancy V_(Zn+O) on doping with Mn^(2+) ions. The intensity of the defect-specific positron lifetime component got reduced initially indicating partial occupancy of the vacancies by the doped cations but then recovered on further doping due to the additional Zn vacancies created as a result of the increasing strain introduced by the Mn ions of larger radius. The creation of a new phase ZnMn_2O_4 thereafter changed the course of variation of the annihilation parameters, as the positrons got increasingly trapped in the vacancies at the tetrahedral and octahedral sites of the spinel nanomanganite.