CFD analysis in an anatomically realistic coronary artery model based on non-invasive 3D imaging: comparison of magnetic resonance imaging with computed tomography

Computational fluid dynamics (CFD) methods based on in vivo three-dimensional vessel reconstructions have recently been shown to provide prognostically relevant hemodynamic data. However, the geometry reconstruction and the assessment of clinically relevant hemodynamic parameters may depend on the used imaging modality. This study compares geometric reconstruction and calculated wall shear stress (WSS) values based on magnetic resonance imaging (MRI) and computed tomography (CT). Both imaging methods were applied to a same 2.5-fold upscale silicon model of the left coronary artery (LCA) main bifurcation. The original model is an optically digitized post mortem vessel cast. This digitized geometry is considered as a “gold standard” or original geometry for the MRI versus CT comparative study. The use of the upscale model allowed generating a high resolution CT raw data set with voxel size of 0.156 × 0.156 × 0.36 mm³ and a high resolution MRI data set with an equivalent voxel size of 0.196 × 0.196 × 0.196 mm³ for corresponding in vivo conditions. MRI based reconstruction achieved a mean Hausdorff surface distance of 0.1 mm to the original geometry. This is 2.5 times better than CT based reconstruction with mean Hausdorff surface distance of 0.252 mm. A comparison of the calculated mean WSS shows good correlation (r = 0.97) and good agreement among the three modalities with a WSS of 0.65 Pa in the original model, of 0.68 Pa in the CT based model and of 0.67 Pa in the MRI based model.     

Lambdoidal synostosis in dizygotic twins with a family history of an undiagnosed connective tissue disorder

Introduction

Unilateral lambdoidal craniosynostosis is a rare disorder that occurs in approximately 3 % of all craniosynostosis phenotypes and only 0.03 % of one million live births. It is even more unusual for this type of synostosis to occur in siblings with only two other cases reported in the literature.

Case report

We report a set of full-term dizygotic twins born with lambdoidal synostosis and a family history of connective tissue and cardiovascular anomalies. One of the twins also had concomitant bicoronal craniosynostosis.

Conclusion

True familial lambdoidal synostosis is exceedingly rare. The present cases in dizygotic twins occurred in a family with a significant history of connective tissue disease suggesting a possible association.     

Double deletion of orexigenic neuropeptide Y and dynorphin results in paradoxical obesity in mice

Objective

Orexigenic neuropeptide Y (NPY) and dynorphin (DYN) regulate energy homeostasis. Single NPY or dynorphin deletion reduces food intake or increases fat loss. Future developments of obesity therapeutics involve targeting multiple pathways. We hypothesised that NPY and dynorphin regulate energy homeostasis independently, thus double NPY and dynorphin ablation would result in greater weight and/or fat loss than the absence of NPY or dynorphin alone.

Design and methods

We generated single and double NPY and dynorphin knockout mice (NPYΔ, DYNΔ, NPYDYNΔ) and compared body weight, adiposity, feeding behaviour, glucose homeostasis and brown adipose tissue uncoupling protein-1 (UCP-1) expression to wildtype counterparts.

Results

Body weight and adiposity were significantly increased in NPYDYNΔ, but not in NPYΔ or DYNΔ. This was not due to increased food intake or altered UCP-1 expression, which were not significantly altered in double knockouts. NPYDYNΔ mice demonstrated increased body weight loss after a 24-h fast, with no effect on serum glucose levels after glucose injection.

Conclusions

Contrary to the predicted phenotype delineated from single knockouts, double NPY and dynorphin deletion resulted in heavier mice, with increased adiposity, despite no significant changes in food intake or UCP-1 activity. This indicates that combining long-term opioid antagonism with blockade of NPY-ergic systems may not produce anti-obesity effects.     

Recurrent deep neck abscess and piriform sinus tract: A 15-year review on the diagnosis and management

Background

Piriform sinus tract (PST) is a rare congenital condition. A delay in diagnosis is common leading to recurrent inflammation.

Method

A retrospective review was performed on all cases of PST treated at a tertiary referral centre between May 1997 and May 2012.

Results

Eighteen patients were reviewed with a mean age of 5.4 years at presentation (ranged from 0 day to 14 years). Most patients presented as acute inflammation (88.9%) and 16 had a left sided lesion. 72.2% of the PST are identified by contrast swallow study. The diagnostic yield was significantly higher if the study was done after the initial acute inflammation settled. Ultrasonography and computer tomography are less sensitive. The median duration from presentation to diagnosis was 17.6 months (ranged 0–120 months). Ten patients (55.6%) experienced recurrent inflammation before confirming the diagnosis. Fistulectomy alone was performed in 15 patients while an additional en-bloc hemithyroidectomy was done in 2 patients.

Conclusion

PST should be suspected in children presenting with a left deep neck abscess. Contrast swallow study is very effective in making diagnosis but has to be postponed after the acute inflammation settles. The condition can be effectively treated by fistulectomy without hemithyroidectomy in majority of our cases.     

Bioengineered kidneys: new sights on a distant horizon

The need for renal replacement therapy is currently rising at an annually increasing rate. Current treatment options for patients with end-stage kidney disease include dialysis or organ transplantation. Yet, even though transplant survival has increased due to refined immunosuppressive therapy, morbidity remains high because of organ shortage. Here we discuss a recent publication that describes the transplantation of a bioengineered biocompatible kidney from a decellularized organ scaffold, thus possibly providing a solution to both transplant organ shortage and morbidity associated with long-term immunosuppression.     

TMPRSS2-ERG Fusions Are Strongly Linked to Young Patient Age in Low-grade Prostate Cancer

Based on next-generation sequencing of early-onset prostate cancer (PCa), we earlier demonstrated that PCa in young patients is prone to rearrangements involving androgen-regulated genes—such as transmembrane protease, serine 2 (TMPRSS2)–v-ets avian erythroblastosis virus E26 oncogene homolog (ERG) fusion—and provided data suggesting that this situation might be caused by increased androgen signaling in younger men. In the same study, an accumulation of chromosomal deletions was found in cancers of elderly patients. To determine how age-dependent molecular features relate to cancer phenotype, an existing data set of 11 152 PCas was expanded by additional fluorescence in situ hybridization analyses of phosphatase and tensin homolog (PTEN), 6q15 and 5q21. The results demonstrate that the decrease in TMPRSS2–ERG fusions with increasing patient age is limited to low-grade cancers (Gleason ≤3 + 4) and that the significant increase in the deletion frequency with age was strictly limited to ERG-negative cancers for 6q15 and 5q21 but to ERG-positive cancers for PTEN. These data suggest that the accumulation of non–androgen-linked genomic alterations with advanced patient age may require an appropriate microenvironment, such as a positive or negative ERG status. The strong link of ERG activation to young patient age and low-grade cancers may help to explain a slight predominance of low-grade cancers in young patients.     

Attention‐network specific alterations of structural connectivity in the undamaged white matter in acute neglect

Visual neglect results from dysfunction within the spatial attention network. The structural connectivity in undamaged brain tissue in neglect has barely been investigated until now. In the present study, we explored the microstructural white matter characteristics of the contralesional hemisphere in relation to neglect severity and recovery in acute stroke patients. We compared age‐matched healthy subjects and three groups of acute stroke patients (9 ± 0.5 days after stroke): (i) patients with nonrecovered neglect (n = 12); (ii) patients with rapid recovery from initial neglect (within the first week post‐stroke, n = 7), (iii) stroke patients without neglect (n = 17). We analyzed the differences between groups in grey and white matter density and fractional anisotropy (FA) and used fiber tracking to identify the affected fibers. Patients with nonrecovered neglect differed from those with rapid recovery by FA‐reduction in the left inferior parietal lobe. Fibers passing through this region connect the left‐hemispheric analogues of the ventral attention system. Compared with healthy subjects, neglect patients with persisting neglect had FA‐reduction in the left superior parietal lobe, optic radiation, and left corpus callosum/cingulum. Fibers passing through these regions connect centers of the left dorsal attention system. FA‐reduction in the identified regions correlated with neglect severity. The study shows for the first time white matter changes within the spatial attention system remote from the lesion and correlating with the extent and persistence of neglect. The data support the concept of neglect as disintegration within the whole attention system and illustrate the dynamics of structural‐functional correlates in acute stroke. Hum Brain Mapp 35:4678–4692, 2014. © 2014 Wiley Periodicals, Inc .