Polycomb group genes are required for neuronal pruning in Drosophila.

BACKGROUND: Pruning that selectively eliminates unnecessary or incorrect neurites is required for proper wiring of the mature nervous system. During Drosophila metamorphosis, dendritic arbourization sensory neurons (ddaCs) and mushroom body (MB) γ neurons can selectively prune their larval dendrites and/or axons in response to the steroid hormone ecdysone. An ecdysone-induced transcriptional cascade plays a key role in initiating neuronal pruning. However, how downstream components of ecdysone signalling are induced remains not entirely understood. RESULTS: Here, we identify that Scm, a component of Polycomb group (PcG) complexes, is required for dendrite pruning of ddaC neurons. We show that two PcG complexes, PRC1 and PRC2, are important for dendrite pruning. Interestingly, depletion of PRC1 strongly enhances ectopic expression of Abdominal B (Abd-B) and Sex combs reduced, whereas loss of PRC2 causes mild upregulation of Ultrabithorax and Abdominal A in ddaC neurons. Among these Hox genes, overexpression of Abd-B causes the most severe pruning defects, suggesting its dominant effect. Knockdown of the core PRC1 component Polyhomeotic (Ph) or Abd-B overexpression selectively downregulates Mical expression, thereby inhibiting ecdysone signalling. Finally, Ph is also required for axon pruning and Abd-B silencing in MB γ neurons, indicating a conserved function of PRC1 in two types of pruning. CONCLUSIONS: This study demonstrates important roles of PcG and Hox genes in regulating ecdysone signalling and neuronal pruning in Drosophila. Moreover, our findings suggest a non-canonical and PRC2-independent role of PRC1 in Hox gene silencing during neuronal pruning.

Postoperative Inflammatory Marker Surveillance in Colorectal Peritoneal Carcinomatosis.

BACKGROUND: The prognostic significance of inflammatory markers in solid cancers is well-established, albeit with considerable heterogeneity. This study sought to investigate the postoperative inflammatory marker trend in peritoneal carcinomatosis (PC), with a focus on colorectal PC (CPC), and to propose optimal surveillance periods and cutoffs. METHODS: Data were collected from a prospectively maintained database of PC patients treated at the authors' institution from April 2001 to March 2019. The platelet-lymphocyte ratio (PLR), the neutrophil-lymphocyte ratio (NLR), and the lymphocyte-monocyte ratio (LMR) were collected preoperatively and on postoperative days 0, 1 to 3, 4 to 7, 8 to 21, 22 to 56, and 57 to 90 as averages. Optimal surveillance periods and cutoffs for each marker were determined by maximally selected rank statistics. The Kaplan-Meier method and Cox proportional hazard regression models were used to investigate the association of inflammatory markers with 1-year overall survival (OS) and recurrence-free survival (RFS) using clinicopathologic parameters. RESULTS: The postoperative inflammatory marker trend and levels did not differ between the patients with and those without hyperthermic intraperitoneal chemotherapy (HIPEC). Low postoperative LMR (days 4-7), high postoperative NLR (days 8-21), and high postoperative PLR (days 22-56) were optimal for prognosticating poor 1-year OS, whereas high postoperative PLR and NLR (days 57-90) and low postoperative LMR (days 8-21) were associated with poor 1-year RFS. A composite score of these three markers was prognostic for OS in CPC. CONCLUSIONS: The reported cutoffs should be validated in a larger population of CPC patients. Future studies should account for the inflammatory response profile when selecting appropriate surveillance periods.

Coronal CT is Comparable to MR Imaging in Aiding Diagnosis of Dementia in a Memory Clinic in Singapore.

PURPOSE: The present study investigated (a) the agreement between computerized tomography (CT) and 3 T magnetic resonance imaging (MRI) in the visual grading of medial temporal atrophy (MTA); and (b) whether MTA on CT differentiated patients with dementia from no dementia in memory clinics. MATERIALS AND METHODS: Data were obtained from patients who underwent CT scans at the National University Hospital of Singapore, and from a subsample who subsequently underwent 3 T MRI scans in a research study. Agreements and disagreements between CT and MRI were determined. Area under the curve (AUC) analyses determined if CT-graded MTA distinguished patients with dementia from no dementia. RESULTS: Of the 107 patients in the subsample, MTA scores of 71 agreed on both CT and MRI. The true positive rate between CT and MRI for MTA scores ≥2 was 79.7%. The true negative rate for MTA scores between 0 and 1 was 96.4%. CT underestimated MTA severity in 33 of 36 disagreements with the MRI. MTA scores ≥2 on CT distinguished dementia from no dementia in both discovery [n=263; AUC (95% confidence interval)=0.77 (0.72-0.83); sensitivity=0.69; specificity=0.74] and validation [n=264; AUC (95% confidence interval)=0.77 (0.71-0.82); sensitivity=0.72; specificity=0.72] groups. CONCLUSIONS: MTA graded on CT is a viable alternative to MRI to aid in the diagnosis of dementia in memory clinics.