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Standard dead-end sample filtration is used to improve sample purity, but is limited as particle build-up fouls the filter, leading to reduced recovery. The fouling layer can be periodically cleared with backflush algorithms applied through a customized fluidic actuator using variable duty cycles, significantly improving particulate recovery percentage. We show a Pulse Width Modulation (PWM) process can periodically backflush the filter membrane to repeatedly interrupt cake formation and reintegrate the fouling layer into the sample, improving net permeate flux per unit volume of sample by partially restoring filter flux capacity. PWM flow for 2.19 um (targeted) and 7.32 um (untargeted) polystyrene microbeads produced 18-fold higher permeate concentration, higher recovery up to 68.5%, and an 8-fold enrichment increase, compared to a uniform flow. As the duty cycle approaches 50%, the recovery percentage monotonically increases after a critical threshold. Further, we developed and validated a mathematical model to determine that fast, small-volume backflush pulses near 50% duty cycle yield higher recovery by decreasing fouling associated with the cake layer. Optimized PWM flow was then used to purify custom particles for immune activation, achieving 3-fold higher recovery percentage and providing a new route to improve purification yields for diagnostic and cellular applications.

Gasdermins are main effectors of pyroptosis, an inflammatory form of cell death. Released by proteolysis, the N-terminal gasdermin domain assembles large oligomers to punch lytic pores into the cell membrane. While the endpoint of this reaction, the fully formed pore, has been well characterized, the assembly and pore-forming mechanisms remain largely unknown. To resolve these mechanisms, we characterize mouse gasdermin-A3 by high-resolution time-lapse atomic force microscopy. We find that gasdermin-A3 oligomers assemble on the membrane surface where they remain attached and mobile. Once inserted into the membrane gasdermin-A3 grows variable oligomeric stoichiometries and shapes, each able to open transmembrane pores. Molecular dynamics simulations resolve how the membrane-inserted amphiphilic β-hairpins and the structurally adapting hydrophilic head domains stabilize variable oligomeric conformations and open the pore. The results show that without a vertical collapse gasdermin pore formation propagates along a set of multiple parallel but connected reaction pathways to ensure a robust cellular response. Gasdermin-A3 pore formation propagates along diverse pathways. It begins with membrane attachment and oligomeric pre-assembly. Once inserted in the membrane, the oligomers re-assemble into various shapes and sizes, which open their lytic pores.

Carbapenem-resistant Acinetobacter baumannii (CRAB) has emerged as a major global pathogen with limited treatment options 1 . No new antibiotic chemical class with activity against A. baumannii has reached patients in over 50 years 1 . Here we report the identification and optimization of tethered macrocyclic peptide (MCP) antibiotics with potent antibacterial activity against CRAB. The mechanism of action of this molecule class involves blocking the transport of bacterial lipopolysaccharide from the inner membrane to its destination on the outer membrane, through inhibition of the LptB 2 FGC complex. A clinical candidate derived from the MCP class, zosurabalpin (RG6006), effectively treats highly drug-resistant contemporary isolates of CRAB both in vitro and in mouse models of infection, overcoming existing antibiotic resistance mechanisms. This chemical class represents a promising treatment paradigm for patients with invasive infections due to CRAB, for whom current treatment options are inadequate, and additionally identifies LptB 2 FGC as a tractable target for antimicrobial drug development. A tethered macrocyclic peptide antibiotic class described here—which shows potent antibacterial activity against carbapenem-resistant Acinetobacter baumannii —blocks the transport of bacterial lipopolysaccharide from the inner membrane to its destination on the outer membrane through inhibition of the LptB 2 FGC complex.

IntroductionInflammatory Bowel Disease (IBD), including Crohn’s disease (CD) and Ulcerative Colitis (UC), is a chronic inflammatory condition with driven by genetic, immune, microbiome, and environmental factors. This study aims to elucidate the cellular and microbial landscape of adult treatment-naive IBD patients with varying disease severity to identify potential disease mechanisms and therapeutic targets, presenting one of the largest IBD single-cell datasets to date.MethodsPatients with suspected IBD were referred to a rapid access IBD ‘Inception’ clinic. Faecal samples were obtained pre-treatment and shotgun metagenomics was undertaken. During the index diagnostic colonoscopy, tissue biopsies were collected from inflamed and non-inflamed regions of the colon in UC and colon + ileum in CD. Single-cell RNA sequencing (scRNA-seq) was performed using 10x Genomics. Baseline clinical metadata and longitudinal therapeutic outcomes were collected over a two-year period for stratification across disease severity and response.ResultsWe analysed 1.4 million cells from 68 treatment-naive IBD patients (38 CD, 30 UC) and 70 symptomatic controls without mucosal inflammation (figure 1). Shotgun metagenomic sequencing was performed on 36 IBD patients with matched scRNA-seq data to explore host-microbe interactions.Our analysis revealed distinct cellular populations and gene expression profiles between IBD patients and controls along the disease severity axis. Specific immune cell subsets were significantly expanded in IBD patients, with inflammatory monocytes particularly prominent in those with higher disease severity, exhibiting upregulated expression of pro-inflammatory cytokines and chemokines. Additionally, a shift from IgA to IgG antibody-producing cells was observed along the disease severity axis, indicating a dysregulated immune response associated with disease progression. Faecal microbial community typing based on pathway abundance revealed two clusters defined by low or high abundance of Bacteroidetes phylum taxa. Integration with clinical metadata and transcriptional profiles showed that Bacteroidetes-high UC patients displayed lower levels of inflammation and up-regulation of interferon signalling in B cells and myeloid cells.Abstract P44 Figure 1ConclusionsThis comprehensive profiling of treatment-naive IBD patients provides valuable insights into the cellular and microbial factors contributing at disease onset. Our findings offer a deeper understanding of the underlying disease pathology along the axis of disease severity, expanding the dynamic range of IBD patient profiling and informing future therapeutic strategies that may more quickly put patients on the right treatment and better address the causes of IBD in addition to the inflammatory response alone.

The self-organized growth of crystalline silicon nanodots and their structural characteristics are investigated. For the nanodot synthesis, thin amorphous silicon (a-Si) layers with different thicknesses have been deposited onto the ultrathin (2 nm) oxidized (111) surface of Si wafers by electron beam evaporation under ultrahigh vacuum conditions. The solid phase crystallization of the initial layer is induced by a subsequent in situ annealing step at 700 °C, which leads to the dewetting of the initial a-Si layer. This process results in the self-organized formation of highly crystalline Si nanodot islands. Scanning electron microscopy confirms that size, shape, and planar distribution of the nanodots depend on the thickness of the initial a-Si layer. Cross-sectional investigations reveal a single-crystalline structure of the nanodots. This characteristic is observed as long as the thickness of the initial a-Si layer remains under a certain threshold triggering coalescence. The underlying ultra-thin oxide is not structurally affected by the dewetting process. Furthermore, a method for the fabrication of close-packed stacks of nanodots is presented, in which each nanodot is covered by a 2 nm thick SiO 2 shell. The chemical composition of these ensembles exhibits an abrupt Si/SiO 2 interface with a low amount of suboxides. A minority charge carrier lifetime of 18 µs inside of the nanodots is determined.