Imaging live bee brains using minimally-invasive diagnostic radioentomology.

The sensitivity of the honey bee, Apis mellifera L. (Hymeonoptera: Apidae), brain volume and density to behavior (plasticity) makes it a great model for exploring the interactions between experience, behavior, and brain structure. Plasticity in the adult bee brain has been demonstrated in previous experiments. This experiment was conducted to identify the potentials and limitations of MicroCT (micro computed tomograpy) scanning "live" bees as a more comprehensive, non-invasive method for brain morphology and physiology. Bench-top and synchrotron MicroCT were used to scan live bees. For improved tissue differentiation, bees were fed and injected with radiographic contrast. Images of optic lobes, ocelli, antennal lobes, and mushroom bodies were visualized in 2D and 3D rendering modes. Scanning of live bees (for the first time) enabled minimally-invasive imaging of physiological processes such as passage of contrast from gut to haemolymph, and preliminary brain perfusion studies. The use of microCT scanning for studying insects (collectively termed 'diagnostic radioentomology', or DR) is increasing. Our results indicate that it is feasible to observe plasticity of the honey bee brain in vivo using diagnostic radioentomology, and that progressive, real-time observations of these changes can be followed in individual live bees. Limitations of live bee scanning, such as movement errors and poor tissue differentiation, were identified; however, there is great potential for in-vivo, non-invasive diagnostic radioentomology imaging of the honey bee for brain morphology and physiology.

Reducing the missing wedge: High-resolution dual axis tomography of inorganic materials.

Electron tomography is a powerful technique that can probe the three-dimensional (3-D) structure of materials. Recently, this technique has been successfully applied to inorganic materials using Z-contrast imaging in a scanning transmission electron microscope to image nanomaterials in 3-D with a resolution of 1 nm in all three spatial dimensions. However, an artifact intrinsic to this technique limits the amount of information obtainable from any object, namely the missing wedge. One way to circumvent this problem is to acquire data from two perpendicular tilt axes, a technique called "dual axis tomography." This paper presents the first dual axis data at high resolution for inorganic materials, and by studying a CdTe tetrapod sample, demonstrates the increase in information obtained using this technique.

Trk inhibitor attenuates the BDNF/TrkB-induced protection of neuroblastoma cells from etoposide in vitro and in vivo.

TrkB activation by brain-derived neurotrophic factor (BDNF) contributes to chemo-resistance in neuroblastoma (NB). AZD6918 is a novel potent and selective inhibitor of the Trk tyrosine kinases. In this study we evaluated the effect of AZD6918 on the sensitivity of TrkB-expressing NB cells or tumors to etoposide, a topoisomerase II inhibitor. TrkB-expressing NB cells were treated with AZD6918 and etoposide in the presence or absence of BDNF in vitro and cell survival was determined. NB xenograft tumors were treated with AZD6918 and etoposide, either alone or in combination in vivo, and the anti-tumor growth effect or mice survival advantage was evaluated. Our study showed that AZD6918 induced cell death as a single agent and attenuated BDNF/TrkB-induced protection from etoposide in vitro. Although AZD6918 alone didn't show anti-tumor growth effect or survival advantage in vivo, a combination of AZD6918 and etoposide had a statistically significant stronger anti-tumor growth effect and survival advantage compared to treatment with either agent alone. Our data indicate that as a Trk inhibitor AZD6918 increased the sensitivity of NB to etoposide. These results extend the spectrum of cytotoxic drugs whose efficacy is increased in combination with Trk inhibitors and support the combination of Trk inhibitors and cytotoxic drugs for NB treatment.

A novel dual-axis iterative algorithm for electron tomography.

A new algorithm for computing electron microscopy tomograms which combines iterative methods with dual-axis geometry is presented. Initial modelling using test data shows several improvements over both the weighted back-projection and simultaneous iterative reconstruction technique methods, with increased stability and tomogram fidelity under high-noise conditions. Preliminary experimental dual-axis reconstructions confirm the viability of the new algorithm.