Cerebral blood perfusion deficits using dynamic susceptibility contrast MRI with gadolinium chelates in rats with post-ischemic reperfusion without significant dynamic contrast-enhanced MRI-derived vessel permeabilities: A cautionary note

In this study, we quantified perfusion deficits using dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) with an extravasating contrast agent (CA). We also investigated the efficacy of leakage compensation from CA pre-load in brains from post-ischemic rat models without significant dynamic contrast-enhanced MRI (DCE-MRI)-derived vessel wall permeability. DSC measurements were obtained using fast (0.3 s) echo-planar imaging in both normal rats and rats with transient middle carotid artery occlusion (MCAO) (1-h MCAO, 24-h reperfusion) after successive administrations of gadoterate meglumine (Dotarem) and intravascular superparamagnetic iron oxide nanoparticles (SPION). The relative cerebral blood volume (CBV) and cerebral blood flow (CBF) values acquired using Dotarem were significantly underestimated (~20%) when compared to those acquired using SPION in ipsilesional post-ischemic brain regions. A slight overestimation of relative mean transit time was observed. Areas with underestimated CBV and CBF values from the corresponding error maps encompassed the area of infarcted tissue (apparent diffusion coefficient < 500 ??m2/s) and mostly coincided with the area wherein conspicuous longitudinal relaxation time differences were observed pre- vs. post-injection of Dotarem. The DSC measurements with significant pre-load (0.3 mmol??kg-1) of Dotarem displayed minimal perfusion deficits when compared to those determined using the reference intravascular SPION

A common origin of complex life cycles in parasitic flatworms: evidence from the complete mitochondrial genome of Microcotyle sebastis (Monogenea: Platyhelminthes)

BACKGROUND: The parasitic Platyhelminthes (Neodermata) contains three parasitic groups of flatworms, each having a unique morphology, and life style: Monogenea (primarily ectoparasitic), Trematoda (endoparasitic flukes), and Cestoda (endoparasitic tapeworms). The evolutionary origin of complex life cyles (multiple obligate hosts, as found in Trematoda and Cestoda) and of endo-/ecto-parasitism in these groups is still under debate and these questions can be resolved, only if the phylogenetic position of the Monogenea within the Neodermata clade is correctly estimated. RESULTS: To test the interrelationships of the major parasitic flatworm groups, we estimated the phylogeny of the Neodermata using complete available mitochondrial genome sequences and a newly characterized sequence of a polyopisthocotylean monogenean Microcotyle sebastis. Comparisons of inferred amino acid sequences and gene arrangement patterns with other published flatworm mtDNAs indicate Monogenea are sister group to a clade of Trematoda+Cestoda. CONCLUSION: Results confirm that vertebrates were the first host for stem group neodermatans and that the addition of a second, invertebrate, host was a single event occurring in the Trematoda+Cestoda lineage. In other words, the move from direct life cycles with one host to complex life cycles with multiple hosts was a single evolutionary event. In association with the evolution of life cycle patterns, our result supports the hypothesis that the most recent common ancestor of the Neodermata giving rise to the Monogenea adopted vertebrate ectoparasitism as its initial life cycle pattern and that the intermediate hosts of the Trematoda (molluscs) and Cestoda (crustaceans) were subsequently added into the endoparasitic life cycles of the Trematoda+Cestoda clade after the common ancestor of these branched off from the monogenean lineage. Complex life cycles, involving one or more intermediate hosts, arose through the addition of intermediate hosts and not the addition of a vertebrate definitive host. Additional evidence is required from monopisthocotylean monogeneans in order to confirm the monophyly of the group

Monophyly of clade III nematodes is not supported by phylogenetic analysis of complete mitochondrial genome sequences

<p>Abstract</p> <p>Background</p> <p>The orders Ascaridida, Oxyurida, and Spirurida represent major components of zooparasitic nematode diversity, including many species of veterinary and medical importance. Phylum-wide nematode phylogenetic hypotheses have mainly been based on nuclear rDNA sequences, but more recently complete mitochondrial (mtDNA) gene sequences have provided another source of molecular information to evaluate relationships. Although there is much agreement between nuclear rDNA and mtDNA phylogenies, relationships among certain major clades are different. In this study we report that mtDNA sequences do not support the monophyly of Ascaridida, Oxyurida and Spirurida (clade III) in contrast to results for nuclear rDNA. Results from mtDNA genomes show promise as an additional independently evolving genome for developing phylogenetic hypotheses for nematodes, although substantially increased taxon sampling is needed for enhanced comparative value with nuclear rDNA. Ultimately, topological incongruence (and congruence) between nuclear rDNA and mtDNA phylogenetic hypotheses will need to be tested relative to additional independent loci that provide appropriate levels of resolution.</p> <p>Results</p> <p>For this comparative phylogenetic study, we determined the complete mitochondrial genome sequences of three nematode species, <it>Cucullanus robustus </it>(13,972 bp) representing Ascaridida, <it>Wellcomia </it><it>siamensis </it>(14,128 bp) representing Oxyurida, and <it>Heliconema longissimum </it>(13,610 bp) representing Spirurida. These new sequences were used along with 33 published nematode mitochondrial genomes to investigate phylogenetic relationships among chromadorean orders. Phylogenetic analyses of both nucleotide and amino acid sequence datasets support the hypothesis that Ascaridida is nested within Rhabditida. The position of Oxyurida within Chromadorea varies among analyses; in most analyses this order is sister to the Ascaridida plus Rhabditida clade, with representative Spirurida forming a distinct clade, however, in one case Oxyurida is sister to Spirurida. Ascaridida, Oxyurida, and Spirurida (the sampled clade III taxa) do not form a monophyletic group based on complete mitochondrial DNA sequences. Tree topology tests revealed that constraining clade III taxa to be monophyletic, given the mtDNA datasets analyzed, was a significantly worse result.</p> <p>Conclusion</p> <p>The phylogenetic hypotheses from comparative analysis of the complete mitochondrial genome data (analysis of nucleotide and amino acid datasets, and nucleotide data excluding 3^rdpositions) indicates that nematodes representing Ascaridida, Oxyurida and Spirurida do not share an exclusive most recent common ancestor, in contrast to published results based on nuclear ribosomal DNA. Overall, mtDNA genome data provides reliable support for nematode relationships that often corroborates findings based on nuclear rDNA. It is anticipated that additional taxonomic sampling will provide a wealth of information on mitochondrial genome evolution and sequence data for developing phylogenetic hypotheses for the phylum Nematoda.</p

MRI investigation of vascular remodeling for heterogeneous edema lesions in subacute ischemic stroke rat models: Correspondence between cerebral vessel structure and function

The spatial heterogeneity in the temporal occurrence of pseudo-normalization of MR apparent diffusion coefficient values for ischemic lesions may be related to morphological and functional vascular remodeling. As the area of accelerated pseudo-normalization tends to expand faster and more extensively into the chronic stage, detailed vascular characterization of such areas is necessary. During the subacute stage of transient middle cerebral artery occlusion rat models, the morphological size of the macrovasculature, microvascular vessel size index (VSI), and microvessel density (MVD) were quantified along with functional perfusion measurements of the relative cerebral blood flow (rCBF) and mean transit time (rMTT) of the corresponding areas (33 cases for each parameter). When compared with typical pseudo-normalization lesions, early pseudo-normalization lesions exhibited larger VSI and rCBF (p &lt; 0.001) at reperfusion days 4 and 7, along with reduced MVD and elongated rMTT (p &lt; 0.001) at reperfusion days 1, 4, and 7. The group median VSI and rCBF exhibited a strong positive correlation (r = 0.92), and the corresponding MVD and rMTT showed a negative correlation (r = -0.48). Light sheet fluorescence microscopy images were used to quantitatively validate the corresponding MRI-derived microvascular size, density, and cerebral blood volume

User-designed device for personalized drug delivery and local treatment of chronic disease

Three-dimensional printing enables precise and on-demand manufacture of customizable drug delivery systems to advance healthcare toward the goal of personalized medicine. However, major challenges remain in realizing personalized drug delivery that fits a patient-specific drug dosing schedule using local drug delivery systems. In this study, a user-designed device is developed as implantable therapeutics that can realize personalized drug release kinetics by programming the inner structural design on the microscale. The drug release kinetics required for various treatments, including dose-dense therapy and combination therapy, can be implemented by controlling the dosage and combination of drugs along with the rate, duration, initiation time, and time interval of drug release according to the device layer design. After implantation of the capsular device in mice, the in vitro???in vivo and pharmacokinetic evaluation of the device is performed, and the therapeutic effect of the developed device is achieved through the local release of doxorubicin. The developed user-designed device provides a novel platform for developing next-generation drug delivery systems for personalized and localized therapy

Pattern recognition analysis of directional intravoxel incoherent motion MRI in ischemic rodent brains

This study aimed to demonstrate a reliable automatic segmentation method for independently separating reduced diffusion and decreased perfusion areas in ischemic stroke brains using constrained nonnegative matrix factorization (cNMF) pattern recognition in directional intravoxel incoherent motion MRI (IVIM???MRI). First, the feasibility of cNMF???based segmentation of IVIM signals was investigated in both simulations and in vivo experiments. The cNMF analysis was independently performed for S0???normalized and scaled (by the difference between the maximum and minimum) IVIM signals, respectively. Segmentations of reduced diffusion (from S0???normalized IVIM signals) and decreased perfusion (from scaled IVIM signals) areas were performed using the corresponding cNMF pattern weight maps. Second, Monte Carlo simulations were performed for directional IVIM signals to investigate the relationship between the degree of vessel alignment and the direction of the diffusion gradient. Third, directional IVIM???MRI experiments (x, y and z diffusion???gradient directions, 20 b values at 7 T) were performed for normal (n = 4), sacrificed (n = 1, no flow) and ischemic stroke models (n = 4, locally reduced flow). The results showed that automatic segmentation of the hypoperfused lesion using cNMF analysis was more accurate than segmentation using the conventional double???exponential fitting. Consistent with the simulation, the double???exponential pattern of the IVIM signals was particularly strong in white matter and ventricle regions when the directional flows were aligned with the applied diffusion???gradient directions. cNMF analysis of directional IVIM signals allowed robust automated segmentation of white matter, ventricle, vascular and hypoperfused regions in the ischemic brain. In conclusion, directional IVIM signals were simultaneously sensitive to diffusion and aligned flow and were particularly useful for automatically segmenting ischemic lesions via cNMF???based pattern recognition

Mean and standard variations of ADC and rCBV error values for infarction, peri-infarction, and normal areas for six rats shown in Figs 4, 5 and 6.

<p>Mean and standard variations of ADC and rCBV error values for infarction, peri-infarction, and normal areas for six rats shown in Figs <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0201076#pone.0201076.g004" target="_blank">4</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0201076#pone.0201076.g005" target="_blank">5</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0201076#pone.0201076.g006" target="_blank">6</a>.</p

Cerebral blood perfusion deficits using dynamic susceptibility contrast MRI with gadolinium chelates in rats with post-ischemic reperfusion without significant dynamic contrast-enhanced MRI-derived vessel permeabilities: A cautionary note - Fig 6

<p>(a.1-d.1) rCBV maps from SPION. (a.2-d.2) rCBV maps from DOTAREM (a.3-d.3) rCBV_error map. (a.4-d.4) Scatter plots of rCBV_SPION/rCBV_DOTAREM values in core region normalized to each normal area. (a.5-d.5) <i>T</i>_<i>1</i> difference maps (post 85 mins) with increasing CA pre-load. No <i>T</i>_<i>1</i> difference map was available for no CA pre-load case and not available.</p

Cerebral blood perfusion deficits using dynamic susceptibility contrast MRI with gadolinium chelates in rats with post-ischemic reperfusion without significant dynamic contrast-enhanced MRI-derived vessel permeabilities: A cautionary note - Fig 5

<p>(a.1) <i>T</i>_<i>2</i>-weighted image. (a.2) ADC map. (a.3) <i>T</i>₁ changes were shown for infarction (green) and normal (blue) region as a function of post-injection time, where injection time-points were marked with red lines. No significant <i>T</i>₁ difference between infarction and normal region were observed from (a.4) <i>T</i>₁ difference map (post-10 mins) after the injection of DOTAREM (0.1 mmol·kg^-1). (a.5) <i>K</i>^<i>trans</i> map. (a.6) <i>V</i>_<i>e</i> map. (a.7) <i>V</i>_<i>p</i> map.</p

Results of in vivo experiment with normal rats (control experiments).

<p>(a) and (b) show the normalized AUC from the first injection (nAUC_Dotarem) and the AUC from the second injection (AUC_Dotarem), respectively. (c) Scatter plot of nAUC_Dotarem and AUC_Dotarem in the left hemisphere (black dots). The red and blue lines are fitted lines to the right- and left-hemisphere scatter plots, respectively. (d) and (e) show the normalized AUC from the first Dotarem injection (nAUC_Dotarem) and the AUC from the second SPION injection (AUC_SPION), respectively. (f) Scatter plot of nAUC_Dotarem and AUC_SPION in the left hemisphere (black dots). The red and blue lines are the corresponding fitted lines to the right- and left-hemisphere scatter plots. (g) Statistical analysis of nAUC ratio. The statistical unit n_sl is the number of slices. The green and yellow bar graphs show the nAUC ratio values in the Dotarem-Dotarem and Dotarem-SPION cases, respectively, in normal rats (green bar: 0.990 ± 0.023 [mean ± standard deviation, <i>n</i> = 3, with 9 slices], yellow bar: 1.002 ± 0.017 [<i>n</i> = 3 with 9 slices], p > 0.05 [p = 0.136]). a.u. means arbitrary unit.</p