Technology advancements in synthesis and modification of nanoscale materials have advanced the development of different medical applications. Nanoparticles (NPs) have demonstrated promising potentials in diagnostic medicine especially for magnetic resonance imaging (MRI). Iron oxide, gold, and gadolinium NPs have been used in preclinical and clinical studies as contrast enhancing agents. Studies are ongoing to find the optimum parameters of these NPs as contrast agents (CAs) of MRI. This study aims to review the recent applications of iron oxide, gold, and gadolinium NPs as contrast enhancing agents in MRI for diagnosis of different disorders. The databases of PubMed (1980PubMed ( -2016, Web of Science (1980Science ( -2016, Scopus (1980), and Google Scholar (1980 were explored using the search terms "Nanoparticles," "Contrast agents," "Magnetic Resonance Imaging" and "disease." The obtained results were screened for the title and abstract and comprehensively reviewed. MRI CAs are divided into T1 and T2 CAs, respectively, used for T1 and T2 weighted protocols in MRI. Iron oxide, gadolinium, and gold NPs are the most common CAs used in MRI. High magnetization values, small size, narrow particle size distribution are the main features of NPs as CAs in MRI. Gadolinium is the most common T1 CAs used in MRI. However, it is associated with toxicity which is a serious concern in patients with renal failure. Iron oxide NPs can be used for these patients. However, the main limitation of iron oxide NPs is limited relaxivity. The relaxivity strongly depends on the size of NP. Paramagnetic NPs serve as T1 CAs and super paramagnetic NPs as T2 CAs. Modulating the size of NPs is the main parameter to adjust different NPs for different MRI protocols. Recent years to overcome the problem of gadolinium and iron oxide NPs, different paramagnetic and super paramagnetic NPs are developed.
Introduction Despite the fact that high-dose radiotherapy is a main therapeutic modality in cancer treatment, recent evidence suggests that it might confer radioresistance. Hyper-radiosensitivity (HRS) is one of the important biological effects of low-dose ionizing radiation (LDIR) in mammalian cell lines. LDIR is considered as a promising assistant method of clinical cancer therapy. The purpose of this study was to evaluate the efficiency of intermittent LDIR followed by a high-dose radiation therapeutic approach compared with the conventional high-dose radiotherapy in the breast cancer MDA-MB-231 cell line. Materials and methods MDA-MB-231 cells were divided into four experimental groups-intermittent LDIR group: cells were irradiated for 10 fractions with a dose of 30 mGy at each time (interval 24 h) followed by 2 Gy, single LDIR group: cells have accepted a dose of 300 mGy LDIR and after 24 h a high dose of 2 Gy, high-dose ionizing radiation (HDIR) group: cells were exposed to a single high dose of 2 Gy, and control group. Results MTT and flow cytometry assay were used for cell proliferation and apoptosis after 24 h of the last irradiation dose (2 Gy). Also, we examined p21 and cespase3 gene expression by RT-qPCR. We observed that intermittent LDIR significantly increased the killing effect of radiotherapy (viability, 71.95 + 1.25%) (P < 0.01). The apoptosis is proposed to increase up to 32.55 + 0.07% in the intermittent LDIR that was markedly higher than those of other groups (P < 0.01). Caspase3 gene expression in this group was the highest (5.2-fold), 4.26-fold and 1.42-fold in single LDIR and HDIR, respectively. It was observed that the intermittent LDIR potentially decreases p21 expression in comparison with the challenge dose of 2 Gy (0.681-fold). Conclusion LDIR may result in HRS through a concurrent increase of apoptosis and a significant decrease in cell viability. The therapeutic effects of this approach should be further investigated in animal models.
Purpose: CDK1A is one of the most important genes that have different key roles in cell lines. This gene has several transcript variants. Investigating of expression of each one actually can be so important because any one of them may have a separate unknown role in cancer cells so can be used to increase therapeutic efficacy. Methods: A549, MDA-MB-231 and Hek-AD cell lines were used in this study. Firstly, three primers for variants of p21 gene were designed by Snapgene and BLAST software. Secondly, the variants expression was checked for each cell lines by RT-qPCR technique, separately. Then the variants that expressed in the cells were selected for more investigation. Finally 2 Gy irradiation was used to evaluate the effect of that on variants expression. Results: The results show that for all cell lines, primer num1 and 3 expressed before any stimuli. After irradiation, for MDA-MB-231 and A549, the expression of primer num3 was decreased, while for Hek-AD no change was observed. The primer num1 expression after the irradiation was different for the cells, V1 expression was decreased in A549 by fold of 0.03 while expression of this for MDA-MB-231 cells was not changed after 2Gy irradiation. Conclusion: It is very necessary to pay attention to the function of each splice variant as well as the response to external stimuli. Understanding the role of each variant in a gene is critical and researchers can use that to improve radiotherapy as well.
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