During radiotherapy, ionizing irradiation interacts with biological systems to produce free radicals, which attack various cellular components. The hematopoietic system is easily recognized to be radiosensitive and its damage may be severe. Melanin nanoparticles (MNPs) act as free radical scavengers prepared by polymerization of dopamine. In this study, a total of 110 male BALB/C mice were divided into five equal groups. Each group contained 22 mice. Mice of group A did not receive MNPs or irradiation (control group), group B was injected intraperitoneally (i.p.) with 50 mg/kg MNPs. Mice of group C and D were exposed to a dose of 7 Gy ɣ-irradiation and injected with the same dose of MNPs as in group B either 30 min pre- or post-irradiation, and group E was exposed to a dose of 7 Gy ɣ-irradiation only. The impact of MNPs on peripheral blood, spleen, and DNA damage induced by irradiation was evaluated by blood count, histopathology of the spleen, and comet assay for the DNA in the bone marrow at 1, 4, 8, and 12 days post-irradiation. Results of group E compared with control group (A) showed a significant depression in complete blood count. Additionally, histopathological observation showed the absence of megakaryocytes with delayed time post-irradiation, deposition of eosinophilic protein of their spleen appeared, as well as a remarkable decrease in spleen size was observed. Moreover, ɣ-irradiation-induced DNA damage as can be inferred from a significant increase by about 5-10 folds in all comet parameters (% of DNA, tail length, tail moment, and olive moment) in the DNA of the bone marrow. In contrast, pre-post treatment with MNPs protected hematopoietic tissues against radiation damage, and therefore, enhanced the survival of mice with 40 % in groups (C&D) compared with 10 % to group (E) till 30 days post-irradiation. In conclusion, these results demonstrated that synthetic MNPs provide significant radioprotection to the hematopoietic tissues.
A. Shouman (2020) Design, synthesis and biological evaluation of a new thieno[2,3-d]pyrimidine-based urea derivative with potential antitumor activity against tamoxifen sensitive and resistant breast cancer cell lines,
The present study aimed to evaluate the association between whole body exposure to extremely low frequency magnetic field (ELF-MF) and genotoxic , cytotoxic hazards in brain and bone marrow cells of newborn rats. Newborn rats (10 days after delivery) were exposed continuously to 50 Hz, 0.5 mT for 30 days. The control group was treated as the exposed one with the sole difference that the rats were not exposed to magnetic field. Comet assay was used to quantify the level of DNA damage in isolated brain cells. Also bone marrow cells were flushed out to assess micronucleus induction and mitotic index. Spectrophotometric methods were used to measure the level of malondialdehyde (MDA) and the activity of glutathione (GSH) and superoxide dismutase (SOD). The results showed a significant increase in the mean tail moment indicating DNA damage in exposed group (P < 0.01, 0.001, 0.0001). Moreover ELF-MF exposure induced a significant (P < 0.01, 0.001) four folds increase in the induction of micronucleus and about three folds increase in mitotic index (P < 0.0001). Additionally newborn rats exposed to ELF-MF showed significant higher levels of MDA and SOD (P < 0.05). Meanwhile ELF-MF failed to alter the activity of GSH. In conclusion, the present study suggests an association between DNA damage and ELF-MF exposure in newborn rats.
Silver nanoparticles (AgNPs) have a wide range of industrial and biomedical applications. The aim of the present study was to determine the cytotoxic and genotoxic effects of AgNPs on Ehrlich carcinoma-bearing mice. AgNPs were characterized by ultraviolet-visible absorption spectroscopy, dynamic light scattering, and transmission electron microscopy (TEM). Furthermore, the cytotoxicity and genotoxicity of AgNPs were evaluated using a series of assays: superoxide dismutase (SOD) enzyme activity, malondialdehyde (MDA) levels, DNA damage (comet assay), and histopathological examination of tissues and tumor size in Ehrlich carcinoma-bearing mice. Treatment of Ehrlich carcinoma-bearing mice with various concentrations of AgNPs (6, 24, and 48 mg/kg) injected intra peritoneal (IP) and intra tumor (IT) revealed that AgNPs significantly elevated the levels (0.5- to 5-fold) of MDA and reduced the activity (32-64%) of SOD. Furthermore, AgNPs caused a 2- to 3-fold increase in comet parameters such as percent tail DNA. Additionally, AgNPs inhibit the promotion of Ehrlich carcinoma by masses of necrotic and fragmented tumor cells. Consequently, the volume of tumor reduced by about 31-95% compared to control one. The results indicate that AgNPs possess cytotoxic and genotoxic effects against Ehrlich tumor and confirm the antitumor properties of AgNPs.
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