The prominent retrocerebellar cerebrospinal fluid (CSF) space can be frequently encountered on paediatric neuroimaging studies. In cases involving abnormal vermian development where imaging does not align with the established criteria of Dandy–Walker malformation (DWM), the term “Dandy–Walker variant or continuum” has been historically employed to describe the aberrant posterior fossa development. Instead, the emphasis is on a more elaborate description of the findings in the posterior fossa. Moreover, combining the findings in the supratentorial brain can occasionally predict certain neurogenetic disorders that mimic Dandy–Walker phenotype. The present review demonstrates and differentiates the imaging features of various entities that result in an enlarged retrocerebellar CSF space, such as inferior vermian hypoplasia (IVH) and several neurogenetic conditions.

The utilization of point-of-care ultrasound (POCUS) has been on rise in recent years, followed by a growing need for comprehensive, compact obstetrics analysis software systems. The accurate computerized assessment of obstetric ultrasound (US) is a challenging task due to the noisy nature of US images and presence of complex anatomies. In this work, we propose a multi-branch deep learning architecture to identify multiple anatomies in obstetric sonography through segmentation and landmark detection. The multi-task deep model is trained to segment the uterus and gestational sac regions, and to localize the position of landmark points denoting the crown and rump of the fetus. We conduct experiments with varying sizes of models, presenting a trade-off between accuracy and efficiency. Our larger models reach average Dice scores of 90% and 91% for segmenting uterus and gestational sac, respectively, and have 1.64 mm average length error for the fetus crown-rump length (CRL) measurement. Furthermore, we present choices for smaller model sizes suitable for integration in portable POCUS devices with limited computing capacities. The smallest model with the most efficient run-time has only about 167.3k parameters, where compared to the larger models, the Dice score is reduced by 4.1% and 6.7% for uterus and gestational sac segmentation, respectively, and the CRL length error is increased by 0.42 mm. This is while the smallest model has 98.8% reduced model size and could smoothly run on naive mobile devices.

The appearance of the paediatric thymus changes as the normal process of thymic involution occurs. Thymic tissue may be orthotopic within the anterior mediastinum or ectopically located along the course of its embryological development. The variable appearance of orthotopic and ectopic thymic tissue in children on imaging studies may lead to misinterpretation of the normal thymus as pathology. Recognition of normal thymic tissue can mitigate unnecessary further diagnostic testing and patient anxiety. In this review, we discuss the embryological development and anatomical variants of normal thymus, and demonstrate the multimodality imaging features of the normal thymus in children, including positron-emission tomography, and diffusion-weighted imaging and in- and opposed-phase imaging on magnetic resonance imaging. We demonstrate the normal thymus mimicking pathological processes and discuss features that distinguish normal thymus, including thymic rebound hyperplasia, from pathology.

BACKGROUND:Clinical trial samples may be stored frozen for prolonged periods before analysis, which can reduce the immunoreactivity of numerous analytes, particularly peptides. We sought to determine the effect of 6 years of frozen storage on serum N-terminal pro-B-type natriuretic peptide (NT-proBNP).METHODS:NT-proBNP was measured from serum samples taken from 99 different patients enrolled in the CanPREDDICT study after <1 year of storage at -70 °C using the Roche first-generation NT-proBNP assay on an e411 instrument. Separate aliquots of the same samples were analyzed after an additional 6 years of storage at -70 °C using the Roche second-generation assay on an e601 instrument.RESULTS:The median NT-proBNP immunoreactivity for the first measurement was 572 pg/mL (interquartile range [IQR] 205-1606, range 49-12820), while after an additional 6 years of storage at -70 °C, this value decreased to 526 pg/mL (IQR 181-1338, range 18-12880), resulting in a median percent difference of -7% (IQR -10.6% to -3.4%, P < 0.001).CONCLUSIONS:We report findings consistent with trends seen in previous work but have investigated the effect of a much longer storage period. Larger percent decreases in NT-proBNP reaching statistical significance are seen, although the median difference is still <10%.

Exposure to particulate matter (PM), a major component of air pollution, contributes to increased morbidity and mortality worldwide. Inhaled PM induces innate immune responses by airway epithelial cells that may lead to the exacerbation or de novo development of airway disease. We have previously shown that 10-μm PM (PM10) activates the nucleotide-binding domain, leucine-rich repeat protein (NLRP) 3 inflammasome in human airway epithelial cells. Our objective was to determine the innate and adaptive immune responses mediated by the airway epithelium NLRP3 inflammasome in response to PM10 exposure. Using in vitro cultures of human airway epithelial cells and in vivo studies with wild-type and Nlrp3(-/-) mice, we investigated the downstream consequences of PM10-induced NLPR3 inflammasome activation on cytokine production, cellular inflammation, dendritic cell activation, and PM10-facilitated allergic sensitization. PM10 activates an NLRP3 inflammasome/IL-1 receptor I (IL-1RI) axis in airway epithelial cells, resulting in IL-1β, CC chemokine ligand-20, and granulocyte/macrophage colony-stimulating factor production, which is associated with dendritic cell activation and lung neutrophilia. Despite these profound innate immune responses in the airway epithelium, the NLRP3 inflammasome/IL-1RI axis is dispensable for PM10-facilitated allergic sensitization. We demonstrate the importance of the lung NLRP3 inflammasome in mediating PM10 exposure-associated innate, but not adaptive, immune responses. Our study highlights a mechanism by which PM10 exposure can contribute to the exacerbation of airway disease, but not PM10-facilitated allergic sensitization.

The histone methyltransferase EZH2 is frequently mutated in germinal center-derived diffuse large B-cell lymphoma and follicular lymphoma. To further characterize these EZH2 mutations in lymphomagenesis, we generated a mouse line where EZH2(Y641F) is expressed from a lymphocyte-specific promoter. Spleen cells isolated from the transgenic mice displayed a global increase in trimethylated H3K27, but the mice did not show an increased tendency to develop lymphoma. As EZH2 mutations often coincide with other mutations in lymphoma, we combined the expression of EZH2(Y641F) by crossing these transgenic mice with Eµ-Myc transgenic mice. We observed a dramatic acceleration of lymphoma development in this combination model of Myc and EZH2(Y641F). The lymphomas show histologic features of high-grade disease with a shift toward a more mature B-cell phenotype, increased cycling and gene expression, and epigenetic changes involving important pathways in B-cell regulation and function. Furthermore, they initiate disease in secondary recipients. In summary, EZH2(Y641F) can collaborate with Myc to accelerate lymphomagenesis demonstrating a cooperative role of EZH2 mutations in oncogenesis. This murine lymphoma model provides a new tool to study global changes in the epigenome caused by this frequent mutation and a promising model system for testing novel treatments.

The histone methyl-transferase EZH2 is frequently affected by gain-of-function mutations in germinal-center lymphoma. To further test if these EZH2 mutations can be driver mutations in lymphomagenesis, we have previously generated and characterized a mouse line transgenic for EZH2Y641F. This mouse model leads to an acceleration of lymphoma development in combination with Myc. We have now further investigated this model system and have used RNAseq and ChIPseq to characterize the effects of mutated EZH2 on gene expression and the epigenome.

Many research efforts have attempted to elucidate the mechanisms by which biofilms confer resistance to antibiotic treatment; this is particularly relevant to opportunistic pathogens, such as Pseudomonas aeruginosa. In previous studies, treatment of P. aeruginosa PAO1 biofilms with alginate lyase was correlated with an increase in cell division based on colony counts observed from plate counting. Given that the alginate cleaving activity of alginate lyase could contribute to artificially increased colony counts, which may be more accurately attributed to better dispersal of biofilm cells, the reliability of using bacterial plating to assay alginate lyase-treated biofilms was investigated. Physically disrupted alginate lyase-treated cells were concurrently treated with a reversible cell division inhibitor, sodium azide, for four hours. Plate counts were taken at regular intervals to monitor changes in cell counts. Alginate lyase-treated cells were observed to enter exponential phase growth sooner than untreated cells, resulting in higher initial plate counts. However, no difference in plate counts was observed between cells treated with alginate lyase and sodium azide, compared to sodium azide alone, thus ruling out enhanced dispersion of biofilms as the reason for increased counts. These results suggest that plate counting is a sufficient method for discerning increased cell division of P. aeruginosa PAO1 biofilms as induced by alginate lyase. Additionally, liberation of cells from the biofilm matrix by this enzyme points to increased growth rate likely due to their release from the biofilm, and subsequently, increased susceptibility to killing by bacteriostatic antibiotics compared to physical disruption.

Abstract Abstract 227 The histone methyl-transferase EZH2 is frequently mutated in germinal-center derived diffuse-large B cell lymphoma (DLBCL) and follicular lymphoma. We and others have demonstrated that these mutations in tyrosine 641 of EZH2 represent a dominant gain-of-function, enhancing the capability to trimethylate H3K27 in combination with wildtype activity (Yap et al, Blood 2011; Sneeringer et al, PNAS 2010). To further test if these EZH2 mutations can be driver mutations in lymphomagenesis we have now generated and characterized a mouse line transgenic for EZH2 Y641F (the most commonly observed mutant form). Transgenic mice were created on the C57/Bl6 background by pronuclear microinjection of a construct where EZH2 Y641F is expressed from a lymphoid specific Emu-lck promoter. Spleen cells isolated from the transgenic mice displayed a global increase in H3K27me3 when analyzed by Western Blot. However none of the mice showed signs of lymphoma even when observed for prolonged periods of time. As EZH2 mutations often coincide with other mutations in lymphoma, we also combined the expression of EZH2 Y641F with the over-expression of Myc by crossing one of the transgenic lines with Emu-myc transgenic mice. In this combination model, we observed a dramatic acceleration of lymphoma development with the combination of Myc and EZH2 Y641F as compared to Myc alone (Myc alone (n=26) 137.5 days, Myc+EZH2 Y641F (n=20) 51 days, p < 0.0001 Log-Rank (Mantel-Cox) Test). The resulting lymphomas are characterized by a generalized massive lymphadenopathy, splenomegaly (spleen weight 0.416 +/− 0.133 g), bone marrow infiltration (72 +/− 8 %) and lymphocytosis (WBC 138.5 +/− 77.1 ×1000/μl). They show histological features of high-grade disease, and initiate disease in secondary recipients. In contrast to lymphomas observed with Emu-myc alone, all of the lymphomas observed in mice transgenic for both, Myc and EZH2 Y641F, presented with a mature B cell phenotype (B220+IgM+). This shift in differentiation can also be observed in the bone marrow even before development of overt lymphomas. While Myc transgenics mainly show an increase in the B220+IgM−compartment, this is shifted towards B220+IgM+ in double transgenics. Cell cycle analysis by in vivo Brdu incorporation before disease onset shows a drastic increase in the fraction of cells in cycle in the splenic B cells of double transgenic mice (43.3 and 44.9 % cells in S phase) as compared to mice transgenic for Myc alone (10.6 % and 14.2 % cells in S phase). Southern Blot analysis using a probe specific for JH4 showed more than one clonal rearrangement in a majority of the lymphomas in the double-transgenic mice. In summary, EZH2 Y641F can collaborate with Emu-myc in high efficiency lymphoma induction. This new murine lymphoma model now provides a powerful tool to study global changes in the epigenome caused by this frequent mutation and may be a useful system for testing novel treatments. Disclosures: No relevant conflicts of interest to declare.