Zinc Nanoparticles Enhance Brain Connectivity in the Canine Olfactory Network: Evidence From an fMRI Study in Unrestrained Awake Dogs

Prior functional Magnetic Resonance Imaging (fMRI) studies have indicated increased neural activation when zinc nanoparticles are added to odorants in canines. Here we demonstrate that zinc nanoparticles up-regulate directional brain connectivity in parts of the canine olfactory network. This provides an explanation for previously reported enhancement in the odor detection capability of the dogs in the presence of zinc nanoparticles. In this study, we obtained fMRI data from awake and unrestrained dogs while they were being exposed to odorants with and without zinc nanoparticles, zinc nanoparticles suspended in water vapor, as well as just water vapor alone. We obtained directional connectivity between the brain regions of the olfactory network that were significantly stronger for the condition of odorant + zinc nanoparticles compared to just odorants, water vapor + zinc nanoparticles and water vapor alone. We observed significant strengthening of the paths of the canine olfactory network in the presence of zinc nanoparticles. This result indicates that zinc nanoparticles could potentially be used to increase canine detection capabilities in the environments of very low concentrations of the odorants, which would have otherwise been undetected

Hemmule: A Novel Structure with the Properties of the Stem Cell Niche

Stem cells are nurtured and regulated by a specialized microenvironment known as stem cell niche. While the functions of the niches are well defined, their structure and location remain unclear. We have identified, in rat bone marrow, the seat of hematopoietic stem cells—extensively vascularized node-like compartments that fit the requirements for stem cell niche and that we called hemmules. Hemmules are round or oval structures of about one millimeter in diameter that are surrounded by a fine capsule, have afferent and efferent vessels, are filled with the extracellular matrix and mesenchymal, hematopoietic, endothelial stem cells, and contain cells of the megakaryocyte family, which are known for homeostatic quiescence and contribution to the bone marrow environment. We propose that hemmules are the long sought hematopoietic stem cell niches and that they are prototypical of stem cell niches in other organs

Magnetoelastic Biosensor Design: an Experimental Study of Sensor Response and Performance

This article presents the results of an investigation into the development and characterization of polyclonal antibody immobilized magnetoelastic biosensors. Langmuir-Blodgett (LB) monolayer technique was employed for antibody (specific to Salmonella. sp) immobilization on rectangular shaped strip magnetoelastic sensors. Biosensor performance was investigated by exposing to graded concentrations (5×101 through 5×108 cfu/ml) of Salmonella typhimurium solutions in a flow through mode. Bacterial binding to the antibody on the sensor surfaces changed the resonance parameters, and these changes were quantified by the sensor’s resonance frequency shift. Biosensor response towards S. typhimurium was measured in different liquid samples (water, fat free milk and apple juice) and as well as in the presence of extraneous microorganisms (Escherichia coli O157:H7 and Listeria monocytogenes). Biosensor performance was characterized by evaluating mechanical merit factor (Q-value) in different liquids, specificity towards various bacterial species and also the thermal stability of biosensor was investigated at different temperatures 25, 45 and 65 °C

Targeting peptides for microglia identified via phage display

Screening with a 7-mer phage display peptide library, a panel of cell-targeting peptides for the murine microglial cell line, EOC 20, was recognized. A number of similar, but not identical, sets of sequences representing more than 75% of all the cell line-binding clones were identified. Comparative analysis indicated that motif S/(T) F T/(X) Y W is present in the vast majority of the binding sequences. The selectivity and specificity of the dominant peptide sequence identified for microglia was confirmed using both phage displaying the peptide and the synthetic peptide alone

Functional MRI of the olfactory system in conscious dogs.

We depend upon the olfactory abilities of dogs for critical tasks such as detecting bombs, landmines, other hazardous chemicals and illicit substances. Hence, a mechanistic understanding of the olfactory system in dogs is of great scientific interest. Previous studies explored this aspect at the cellular and behavior levels; however, the cognitive-level neural substrates linking them have never been explored. This is critical given the fact that behavior is driven by filtered sensory representations in higher order cognitive areas rather than the raw odor maps of the olfactory bulb. Since sedated dogs cannot sniff, we investigated this using functional magnetic resonance imaging of conscious dogs. We addressed the technical challenges of head motion using a two pronged strategy of behavioral training to keep dogs' head as still as possible and a single camera optical head motion tracking system to account for residual jerky movements. We built a custom computer-controlled odorant delivery system which was synchronized with image acquisition, allowing the investigation of brain regions activated by odors. The olfactory bulb and piriform lobes were commonly activated in both awake and anesthetized dogs, while the frontal cortex was activated mainly in conscious dogs. Comparison of responses to low and high odor intensity showed differences in either the strength or spatial extent of activation in the olfactory bulb, piriform lobes, cerebellum, and frontal cortex. Our results demonstrate the viability of the proposed method for functional imaging of the olfactory system in conscious dogs. This could potentially open up a new field of research in detector dog technology

Cluster-level statistics of activations for parametric modulation of awake dogs.^*

<p>*: ROIs shown in bold face were commonly activated for low (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086362#pone-0086362-t003" target="_blank">Table 3</a>) and high (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086362#pone-0086362-t004" target="_blank">Table 4</a>) odor concentration, as well as parametric modulation by odor concentration.</p

Comparison of activation maps with and without camera motion tracking parameters as regressors.

<p>(Overall FDR = 0.05, cluster threshold  = 15 voxels using AlphaSim, t-contrast) The activtion maps were for low concentration (0.016 mM) in awake dogs. The activation map obtained with only SPM realignment parameters as regressors is shown in cool colormap. The activation map with camera motion tracking parameters and SPM realignment parameters as regressors is shown in hot colormap. The common areas are overlaid such that they appear as purple. We found 3 clusters, 379 voxels in cool-colored map (same as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086362#pone-0086362-t003" target="_blank">Table 3</a>); 3 clusters, 396 voxels in hot-colorred map, and 3 clusters, 340 voxels in the common area. (A: Anterior, P: posterior, S: superior, I: inferior, L: left, R: right)</p