Nagoya University

This paper examines the evolution of microplastic (MP) size distributions fragmented from photo-aged polypropylene (PP) in stirred water. PP specimens fragmented into MPs with their size of 1-30μm after UV irradiation and stirring in laboratory settings. These laboratory-fragmented MPs were dispersed into the water during the stirring process. A series of MP size distributions was analyzed from optical microscope images of obtained MPs. The MP size distribution was described by an exponential function in the short stirring period, whereas it changed to a power-law function as the stirring time increased. The fragmentation rate of MPs and nanoplastics (NPs) decreased with increasing stirring time. The obtained MP exhibited higher crystallinity than the photo-aged PP specimen after stirring. This result implies that MP fragmentation, as observed under controlled laboratory conditions, is related with the chemi-crystallization of PP.

Effective biomolecule size discrimination is essential for bioanalysis and biomedical engineering. However, traditional techniques for discriminating large DNA molecules, such as pulsed-field gel electrophoresis, are time-consuming, while micro/nanofluidic devices that use nanostructured molecular sieves are costly and impractical for large-scale production. We hypothesized that polymer brush films could effectively separate large DNA by size, functioning as nanoscale molecular sieves. We prepared 100 nm-high hydrated polymer brush films from 2-methacryloyloxyethyl phosphorylcholine and examined the electrophoretic mobility of adsorbed λ and T4 DNA (48.5 and 166 kbp, respectively). We visualized individual DNA molecules under different electric fields using fluorescence microscopy and investigated their electrophoretic behavior at the brush–solution interface using neutron reflectivity. We found that DNA mobility in polymer brushes becomes strongly size-dependent above a critical electric field, enabling precise size discrimination. Higher voltages and larger DNA sizes result in more complex morphologies, indicating more frequent DNA–brush interactions. Neutron reflectivity confirmed that stronger electric fields draw DNA molecules closer to the substrate, enhancing DNA–brush interactions and reducing size-exclusion effects. In polymer brush films, DNA–matrix interactions are controlled by electric field strength, unlike in gel electrophoresis, where they rely on polymer density. Optimized polymer brush electrophoresis enables rapid and precise mobility-based size discrimination from single-molecule tracking and simplifies DNA recovery owing to the absence of a three-dimensional mesh structure. These observations highlight the potential of polymer brush films for biomolecular discrimination and analysis, thereby advancing their application in molecular biology and clinical diagnostics. • Polymer brush films offer a soft, scalable alternative to gel-based DNA sieving • Electric field strength regulates DNA–brush interactions • DNA mobility becomes size-dependent above a critical electric field • Larger DNA adopts complex conformations and shows reduced migration speed • Neutron reflectivity shows DNA shifts closer to the substrate under stronger fields

In congenital diaphragmatic hernia, postoperative right-left asymmetry of pulmonary perfusion affects outcome. Although pulmonary perfusion scintigraphy (PPS) is widely used to assess pulmonary perfusion, it requires the use of radionuclides and peripheral venous access. In contrast, dynamic digital radiography (DDR) visualizes and analyzes pulmonary perfusion by extracting subtle changes in X-ray attenuation from sequential images acquired using a pulsed X-ray generator and a flat-panel detector. This study aimed to evaluate the accuracy of DDR for assessing pulmonary perfusion in children and verify the associated radiation dose. Consecutive congenital diaphragmatic hernia survivors aged 5-7years scheduled for routine PPS between January 2024 and June 2025 underwent DDR on the same day. The images were analyzed using a dedicated workstation. For each modality, we calculated the blood-flow ratio in the affected lung and assessed the agreement using Pearson correlation and Bland-Altman analysis. Effective doses were also compared. Thirteen children (median age, 6.07years; 10 left-sided diaphragmatic hernia) were included in the study. DDR-derived blood-flow ratio strongly correlated with PPS (r=0.977, P<0.01), with absolute inter-method blood-flow ratio differences <5%. Neither fixed nor proportional bias was observed. The median effective dose for DDR was 0.16mSv-significantly lower than that for PPS (2.09mSv). The blood-flow ratio calculated using DDR correlated well with the scintigraphy results. DDR could serve as a minimally invasive, low-dose alternative to PPS for the evaluation of pulmonary perfusion. Future validation in a broader pediatric population is warranted.

Recent studies have shown that cancer-associated fibroblasts (CAFs), a key component of the tumor microenvironment, are heterogeneous and can be divided into distinct subsets. Although all CAFs were believed to promote tumor progression, recent studies have identified a distinguished subset of tumor-restraining CAFs (rCAFs). It was previously demonstrated that the up-regulation of Meflin (immunoglobulin superfamily containing leucine-rich repeat) expression confers a tumor-restraining role on CAFs in pancreatic, colon, urothelial, and lung cancers. Triple-negative breast cancer (TNBC) is an aggressive type of breast cancer with a poor prognosis. In this study, it was shown that Meflin can be a candidate marker for rCAFs in TNBC. In co-culture experiments with tumor cells and fibroblasts, Meflin overexpression in fibroblasts inhibited tumor cell growth in a three-dimensional culture model and shifted their gene expression profile toward that characteristic of universal or normal fibroblasts. Meflin overexpression in fibroblasts significantly reduced the expression of the chemokine receptor ACKR3 and enhanced that of the prostaglandin synthase PTGDS. This is suggestive of the involvement of these proteins in tumor microenvironment regulation. Furthermore, Meflin deficiency reduced the area of tumor vessels in a TNBC mouse model, highlighting its role in CAF-mediated inhibition of TNBC progression and improvement of drug delivery. Accordingly, Meflin plays a role as a potential functional marker of rCAFs in TNBC.