Search

Many species of the gastropod genus Philine have been named from northeastern Asia but scanty descriptions based predominantly on shells make it difficult to determine which are valid. This, plus the sporadic anatomical and genetic information available for many of these species has led to what may be described as an un-integrated taxonomy. In this situation, it is generally preferable to postpone dissection of rare and unusual specimens until relevant diagnostic characters can be established in broader studies. Micro-CT scanning and DNA sequencing were used to examine such a specimen collected recently from deep waters off northeastern Taiwan. Micro-CT examination of the morphology of the internal shell and gizzard plates suggested that, among named species, the sequenced specimen is most similar to P. otukai. It cannot, however, be definitively referred to P. otukai as that species lacks adequate anatomical description or known DNA sequences. Phylogenetic analyses of newly collected DNA sequences show the specimen to be most closely related to, but distinct from the northern Atlantic Ocean and Mediterranean species, Philine quadripartita. The sequences also confirm genetically that five or more species of Philine occur in northeast Asia, including at least three subject to considerable taxonomic uncertainty.

Efficacy of diagnostics and therapeutics for brain tumours can be modulated by vascular delivery and blood brain barrier permeability. Simultaneous dynamic gadolinium MR-PET enables independent assessment of vascular delivery and blood brain barrier integrity in a brain tumour animal model in the presence of a PET tracer.Dual echo dynamic gadolinium enhanced gradient echo imaging allows simultaneous calculation of T2* and T1 images from the TE image pairs. Relaxivity values then enabled determination of independent T2*- and T1-derived gadolinium concentrations simultaneously with measurement of [18F]DPA-714 neuroinflammation radiotracer delivery.Separate T2*- and T1-derived gadolinium concentrations curves were derived in a selection of tumours and normal tissue, reflecting vascular delivery and tissue uptake. Changes in the PET activity curves were seen in tumours and normal tissue, reflecting changes in the MR derived dynamic curves. The dramatic changes in the MR-derived vascular delivery and tissue uptake estimates may improve the understanding of the alteration of delivery and uptake of new theranostic agents.

Magnetic Resonance Imaging (MRI) of the rodent brain at ultra-high magnetic fields (> 9.4 Tesla) offers a higher signal-to-noise ratio that can be exploited to reduce image acquisition time or provide higher spatial resolution. However, significant challenges are presented due to a combination of longer T1 and shorter T2/T2* relaxation times and increased sensitivity to magnetic susceptibility resulting in severe local-field inhomogeneity artefacts from air pockets and bone/brain interfaces. The Stejskal-Tanner spin echo diffusion-weighted imaging (DWI) sequence is often used in high-field rodent brain MRI due to its immunity to these artefacts. To accurately determine diffusion-tensor or fibre-orientation distribution, high angular resolution diffusion imaging (HARDI) with strong diffusion weighting (b >3000 s/mm2) and at least 30 diffusion-encoding directions are required. However, this results in long image acquisition times unsuitable for live animal imaging. In this study, we describe the optimization of HARDI acquisition parameters at 16.4T using a Stejskal-Tanner sequence with echo-planar imaging (EPI) readout. EPI segmentation and partial Fourier encoding acceleration were applied to reduce the echo time (TE), thereby minimizing signal decay and distortion artefacts while maintaining a reasonably short acquisition time. The final HARDI acquisition protocol was achieved with the following parameters: 4 shot EPI, b = 3000 s/mm2, 64 diffusion-encoding directions, 125×150 μm2 in-plane resolution, 0.6 mm slice thickness, and 2h acquisition time. This protocol was used to image a cohort of adult C57BL/6 male mice, whereby the quality of the acquired data was assessed and diffusion tensor imaging (DTI) derived parameters were measured. High-quality images with high spatial and angular resolution, low distortion and low variability in DTI-derived parameters were obtained, indicating that EPI-DWI is feasible at 16.4T to study animal models of white matter (WM) diseases.