Methods in molecular biology
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Molecular diffusion plays an important role in many biological phenomena. Magnetic Resonance (MR) imaging is inherently sensitive to diffusion and can be used to help understand diffusion processes. Diffusion MR imaging is most widely used for imaging the ischemic brain. ⋯ DTI studies in these settings can be accomplished with high resolution and can offer exquisite contrast, but the technical and practical challenges can sometimes be different than those seen on clinical MRI scanners. Here, a stepwise methodology is presented for using small-bore, high field strength scanners (>3 T) for DTI. This chapter is aimed at addressing readers with no prior knowledge of DTI and we present both a basic explanation of underlying principles and a practical approach to the experiment.
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Therapeutic strategies for cancer include chemotherapy, immunotherapy, and radiation. Such therapies result in significant short-term clinical responses; however, relapses and recurrences occur with no treatments. Targeted therapies using monoclonal antibodies have improved responses with minimal toxicities. ⋯ In comparison with the sensitive parental cells, the RR clones are refractory to rituximab-mediated cell signaling and chemosensitization. Noteworthy, interference with the hyperactivated survival/antiapoptotic pathways in the RR clones with various pharmacological inhibitors mimicked rituximab effects in the parental cells. The development of RR clones provides a paradigm for studying resistance by other anticancer monoclonal antibodies in various tumor models.
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Here we describe MRI and (1)H MRS protocols for the investigation of animal models (mainly mice and rats) of psychiatric disorders. The introduction provides general findings from brain imaging studies in patients with psychiatric diseases and refers to general rules regarding the use of animal models in research. The methods section includes a selection of basic 9.4 T MRI and MRS protocols applicable for the investigation of animal models of psychiatric disorders (T1W, T2W, FLAIR, (1)H MRS). The notes section discusses in detail a series of factors that can influence the outcome of the experiment: from animal handling, stress-triggering aspects, and experimental design-related factors to technical aspects that affect T (1) and T (2) measurements.
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Large numbers of diverse small non-coding RNAs have been discovered and characterized in eukaryotic RNA interference pathways. These small RNAs have distinctive characteristics and are associated with Argonaute family proteins to regulate gene expression and genomes at various levels. These small RNAs include the Dicer-dependent group such as microRNAs (miRNAs) and small interfering RNAs (siRNAs), and the Dicer-independent group such as Piwi-interacting RNAs (piRNAs). This review summarizes the various classes of eukaryotic small RNAs and the general knowledge of their characteristics, biogenesis, and functions, with emphasis on some of the recently identified small RNAs.
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Duchenne muscular dystrophy (DMD) is caused by mutations that disrupt the reading frame of the human DMD gene. Selective removal of exons flanking an out-of-frame DMD mutation can result in an in-frame mRNA transcript that may be translated into an internally deleted, Becker muscular dystrophy (BMD)-like, but functionally active dystrophin protein with therapeutic activity. Antisense oligonucleotides (AOs) can be designed to bind to complementary sequences in the targeted mRNA and modify pre-mRNA splicing to correct the reading frame of a mutated transcript so that gene expression is restored. ⋯ However, it should be noted that personalized molecular medicine may be necessary, since the various reading frame-disrupting mutations are spread across the DMD gene. The different deletions that cause DMD would require skipping of different exons, which would require the optimization and clinical trial workup of many specific AOs. This chapter describes the methodologies available for the optimization of AOs, and in particular phosphorodiamidate morpholino oligomers (PMOs), for the targeted skipping of specific exons on the DMD gene.