Evaluation of Magnetic Micro- and Nanoparticle Toxicity to Ocular Tissues

Purpose: Magnetic nanoparticles (MNPs) may be used for focal delivery of plasmids, drugs, cells, and other applications. Here we ask whether such particles are toxic to ocular structures. Methods: To evaluate the ocular toxicity of MNPs, we asked if either 50 nm or 4 mm magnetic particles affect intraocular pressure, corneal endothelial cell count, retinal morphology including both cell counts and glial activation, or photoreceptor function at different time points after injection. Sprague-Dawley rats (n = 44) were injected in the left eye with either 50 nm (3 ml, 1.65 mg) or 4 mm(3ml, 1.69 mg) magnetic particles, and an equal volume of PBS into the right eye. Electroretinograms (ERG) were used to determine if MNPs induce functional changes to the photoreceptor layers. Enucleated eyes were sectioned for histology and immunofluorescence. Results: Compared to control-injected eyes, MNPs did not alter IOP measurements. ERG amplitudes for a-waves were in the 100–250 mV range and b-waves were in the 500–600 mV range, with no significant differences between injected and noninjected eyes. Histological sectioning and immunofluorescence staining showed little difference in MNP-injected animals compared to control eyes. In contrast, at 1 week, corneal endothelial cell numbers were significantly lower in the 4 mm magnetic particle-injected eyes compared to either 50 nm MNP- or PBS-injected eyes. Furthermore, iron deposition was detected after 4 mm magnetic particle but not 50 nm MNP injection

A proposal to determine the distribution of lateral forces from loaded recycled plastic drainage kerbs

Abstract: This study presents a detailed analysis of the lateral forces generated as a result of vertically applied loads to recycled plastic drainage kerbs. These kerbs are a relatively new addition to road infrastructure projects. When concrete is used to form road drainage kerbs, its deformation is minimum when stressed under heavy axle loads. Although recycled plastic kerbs are more environmentally friendly as a construction product, they are less stiff than concrete and tend to deform more under loading leading to a bursting type, lateral force being applied to the haunch materials, the magnitude of which is unknown. A method is proposed for establishing the distribution of these lateral forces resulting from deformation under laboratory test conditions. A load of 400 kN is applied onto a total of six typical kerbs in the laboratory in accordance with the test standard. The drainage kerbs are surrounded with 150 mm of concrete to the front and rear haunch and underneath as is normal during installation. The lateral forces exerted on the concrete surround as a result of deformation of the plastic kerbs are determined via a strain measuring device. Analysis of the test data allows the magnitude of the lateral forces to the surrounding media to be determined and, thereby, ensuring the haunch materials are not over-stressed as a result. The proposed test methodology and subsequent analysis allows for an important laboratory-based assessment of any typical recycled plastic drainage kerbs to be conducted to ensure they are fit-for-purpose in the field

Identification of therapeutic targets in a model of neuropathic pain

Neuropathic pain (NP) is caused by damage to the nervous system, resulting in dysfunction and aberrant pain. The cellular functions (e.g. peripheral neuron spinal cord innervation, neuronal excitability) associated with NP often develop over time and are likely associated with gene expression changes. Gene expression studies on the cells involved in NP (e.g. sensory dorsal root ganglion neurons) are publically available; the mining of these studies may enable the identification of novel targets and the subsequent development of therapies that are essential for improving quality of life for the millions of individuals suffering with NP. Here we analyzed a publically available microarray dataset (GSE30165) in order to identify new RNAs (e.g. messenger RNA isoforms and non-coding RNAs) underlying NP. GSE30165 profiled gene expression in dorsal root ganglion neurons (DRG) and in sciatic nerve (SN) after resection, a NP model. Gene ontological analysis shows enrichment for sensory and neuronal processes. Protein network analysis demonstrates DRG upregulated genes typical to an injury and NP response. Of the top changing genes, 34% and 36% are associated with more than one protein coding isoform in the dorsal root ganglia (DRG) and sciatic nerve (SN) respectively. The majority of genes are receptor and enzymes. We identified fifteen long non-coding RNAs (lncRNAs) targeting these genes in LNCipedia.org, an online comprehensive lncRNA database. These RNAs represent new therapeutic targets for preventing NP development and this approach demonstrates the feasibility of data reanalysis for their identification

Identification of therapeutic targets in a model of neuropathic pain

Neuropathic pain (NP) is caused by damage to the nervous system, resulting in dysfunction and aberrant pain. The cellular functions (e.g. peripheral neuron spinal cord innervation, neuronal excitability) associated with NP often develop over time and are likely associated with gene expression changes. Gene expression studies on the cells involved in NP (e.g. sensory dorsal root ganglion neurons) are publically available; the mining of these studies may enable the identification of novel targets and the subsequent development of therapies that are essential for improving quality of life for the millions of individuals suffering with NP. Here we analyzed a publically available microarray dataset (GSE30165) in order to identify new RNAs (e.g. messenger RNA isoforms and non-coding RNAs) underlying NP. GSE30165 profiled gene expression in dorsal root ganglion neurons (DRG) and in sciatic nerve (SN) after resection, a NP model. Gene ontological analysis shows enrichment for sensory and neuronal processes. Protein network analysis demonstrates DRG upregulated genes typical to an injury and NP response. Of the top changing genes, 34% and 36% are associated with more than one protein coding isoform in the dorsal root ganglia (DRG) and sciatic nerve (SN) respectively. The majority of genes are receptor and enzymes. We identified fifteen long non-coding RNAs (lncRNAs) targeting these genes in LNCipedia.org, an online comprehensive lncRNA database. These RNAs represent new therapeutic targets for preventing NP development and this approach demonstrates the feasibility of data reanalysis for their identification

Emerging Putative Associations between Non-Coding RNAs and Protein-Coding Genes in Neuropathic Pain: Added Value from Reusing Microarray Data

Regeneration of injured nerves is likely occurring in the peripheral nervous system, but not in the central nervous system. Although protein-coding gene expression has been assessed during nerve regeneration, little is currently known about the role of non-coding RNAs (ncRNAs). This leaves open questions about the potential effects of ncRNAs at transcriptome level. Due to the limited availability of human neuropathic pain (NP) data, we have identified the most comprehensive time-course gene expression profile referred to sciatic nerve (SN) injury and studied in a rat model using two neuronal tissues, namely dorsal root ganglion (DRG) and SN. We have developed a methodology to identify differentially expressed bioentities starting from microarray probes and repurposing them to annotate ncRNAs, while analyzing the expression profiles of protein-coding genes. The approach is designed to reuse microarray data and perform first profiling and then meta-analysis through three main steps. First, we used contextual analysis to identify what we considered putative or potential protein-coding targets for selected ncRNAs. Relevance was therefore assigned to differential expression of neighbor protein-coding genes, with neighborhood defined by a fixed genomic distance from long or antisense ncRNA loci, and of parental genes associated with pseudogenes. Second, connectivity among putative targets was used to build networks, in turn useful to conduct inference at interactomic scale. Last, network paths were annotated to assess relevance to NP. We found significant differential expression in long-intergenic ncRNAs (32 lincRNAs in SN and 8 in DRG), antisense RNA (31 asRNA in SN and 12 in DRG), and pseudogenes (456 in SN and 56 in DRG). In particular, contextual analysis centered on pseudogenes revealed some targets with known association to neurodegeneration and/or neurogenesis processes. While modules of the olfactory receptors were clearly identified in protein–protein interaction networks, other connectivity paths were identified between proteins already investigated in studies on disorders, such as Parkinson, Down syndrome, Huntington disease, and Alzheimer. Our findings suggest the importance of reusing gene expression data by meta-analysis approaches

Experimental groups.

<p>3 animals were studied per group, but IOP and histology data for PBS-injected right eyes were pooled into groups irrespective of left eye treatment.</p><p>*1 month survival groups were only subjected to histology and iron staining, not IOP or immunofluorescence measurements.</p><p>**A set of uninjected animals was used exclusively for ERG measurements. IVT intravitreal; AC anterior chamber; PBS phosphate buffered saline.</p

Iron deposits in the ocular tissues after particle injections.

<p>Representative images from Prussian blue histochemical staining for iron from control and magnetic particle-injected eyes at 1 week. Iron staining was observed only in the positive control, and not in any of the injected eyes, as marked. The 4 µm particles were visible in the iris and retinal tissues (arrows).</p

Hematoxylin- and eosin-stained sections.

<p>Hematoxylin- and eosin-stained representative sections for the PBS- (control), 50 nm- and 4 µm- injected animals at 1 week and 5 months, as marked. Accumulation of 4 µm particles were noted layered against the retina (IVT injection, green arrows) and along the iris and in the angle (AC injection, blue arrows) out to 5 months. Yellow arrows highlight example dotted cell nuclei in the GCL (yellow dots), INL (green dots) and ONL (red dots) at higher magnification used for cytotoxicity counting. Black arrows point to corneal endothelial cells along the endothelial cell layer, used for cytotoxicity counting. Scale bar, 50 µm in all pictures.</p

Measure of electroretinograms changes in response to magnetic particles.

<p>Electroretinograms taken at 9–14 weeks for 50 nm- and 4 µm-, AC- and IVT-injected animals, as well as control, uninjected animals, as marked. The solid line represents the average of the particle-injected left eyes for each group, and the dashed line represents the average of the PBS-injected right eyes for each group, except in the control animals (1^st column) in which neither eye was injected. There was no significant difference in the a- and b-waves for the control (uninjected) and nano- and microparticle injected animals with either IVT or AC injections.</p