Nanotechnology has advanced at an extremely rapid pace over the past several years in numerous fields of research. However, the uptake of nanoparticles (NPs) into the body after administration through various routes may pose a risk to human health. In this study, we investigated the potential ocular toxicity of 20-nm, negatively- charged zinc oxide (ZnO) NPs in rats using micro-computed tomography (micro-CT) and histopathological assessment. Animals were divided into four groups as control group, ZnO NPs treatment group (500 mg/kg/day), control recovery group, and ZnO NPs treatment and recovery group. Ocular samples were prepared from animals treated for 90 days (10 males and 10 females, respectively) and from recovery animals (5 males and 5 females, respectively) sacrificed at 14 days after final treatment and were compared to age-matched control animals. Micro-CT analyses represented the deposition and distribution of foreign materials in the eyes of rats treated with ZnO NPs, whereas control animals showed no such findings. X-ray fluorescence spectrometry and energy dispersive spectrometry showed the intraocular foreign materials as zinc in treated rats, whereas control animals showed no zinc signal. Histopathological examination revealed the retinopathy in the eyes of rats treated with ZnO NPs. Neuronal nuclei expression was decreased in neurons of the ganglion cell layer of animals treated with ZnO NPs compared to the control group. Taken together, treatment with 20-nm, negatively-charged ZnO NPs increased retinopathy, associated with local distribution of them in ocular lesions.
To identify preneoplastic markers for hepatocarcino-genesis, the expression levels of neighbor of Punc E11 (Nope), E-cadherin and α-fetoprotein (AFP) were investigated in carcinogen-treated embryonic cell lineages. Mouse embryonic stem cells (ESCs), hepatic progenitor cells (HPCs), and hepatocyte‑like cells (HCs) representing 0, 22, and 40 days of liver differentiation, respectively, were treated in vitro with diethylnitrosamine (DEN) at 4 doses (0, 1, 5, and 15 mM) for 24 h. The expression of Nope, E-cadherin and AFP was examined by quantitative real-time PCR, western blotting and immunocytochemistry. DEN treatment significantly increased the mRNA expression of Nope in ESCs and HPCs, and that of E-cadherin and AFP in all three cell lines, although the changes in expression were triggered by varying DEN concentrations. Immunofluorescence staining revealed that Nope was expressed at the cell membrane in ESCs and HPCs and within granules or in the cytoplasm of HCs, which was also stained by E-cadherin. DEN treatment induced Nope expression in ESCs, HPCs and HCs and caused a concomitant increase in E-cadherin expression. Although Nope expression clearly increased following tumor induction, its expression pattern changed with the developmental stage. In conclusion, we determined that Nope expression may carry prognostic significance during early hepatocarcinogenesis. Moreover, Nope expression may serve as a novel oncofetal surface marker for preneoplastic stages that are not identifiable by the commonly used marker, AFP.
Calcium phosphate ceramics such as hydroxy apatite (HA), β-tricalcium phosphate (β-TCP) and bicalcium phosphate (BCP) have been used as a bone graft biomaterial because of their good biocompatibility and similarity of chemical composition to natural bones. To increase the mechanical and osteoconductive properties, the granules and spongy type porous bone graft substitutes were prepared by fibrous monolithic process and polyurethane foam replica methods, respectively. The pore sizes obtained using these approaches ranged between 100-600 µm. The cytotoxicity, cellular proliferation, differentiation and ECM deposition on the bone graft substitutes were observed by SEM and confocal microscopy. Moreover, the scaffolds were implanted in the rabbit femur. New bone formation and biodegradation of bone graft were observed through follow-up X-ray, micro-CT analysis and histological findings. After several months (2, 3, 6, 12 and 24 months) of implantation, new bone formation and ingrowths were observed in defect sites of the animal by CaP ceramics and 2 to 3 times higher bone ingrowths were confirmed than that of the normal trabecular bones in terms of total bone volume (BV).
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