Synovial macrophage diversity and activation of M-CSF signaling in post-traumatic osteoarthritis.

Objective: Synovium is home to immune and stromal cell types that orchestrate inflammation following a joint injury; in particular, macrophages are central protagonists in this process. We sought to define the cellular and temporal dynamics of the synovial immune niche in a mouse model of post-traumatic osteoarthritis (PTOA), and to identify stromal-immune crosstalk mechanisms that coordinate macrophage function and phenotype. Design: We induced PTOA in mice using a non-invasive tibial compression model of anterior cruciate ligament rupture (ACLR). Single cell RNA-seq and flow cytometry were used to assess immune cell populations in healthy (Sham) and injured (7d and 28d post-ACLR) synovium. Characterization of synovial macrophage polarization states was performed, alongside computational modeling of macrophage differentiation, as well as implicated transcriptional regulators and stromal-immune communication axes. Results: Immune cell types are broadly represented in healthy synovium, but experience drastic expansion and speciation in PTOA, most notably in the macrophage portion. We identified several polarization states of macrophages in synovium following joint injury, underpinned by distinct transcriptomic signatures, and regulated in part by stromal-derived macrophage colony-stimulating factor signaling. The transcription factors Pu.1, Cebpα, Cebpß, and Jun were predicted to control differentiation of systemically derived monocytes into pro-inflammatory synovial macrophages. Conclusions: We defined different synovial macrophage subpopulations present in healthy and injured mouse synovium. Nuanced characterization of the distinct functions, origins, and disease kinetics of macrophage subtypes in PTOA will be critical for targeting these highly versatile cells for therapeutic purposes.

At-home testing to mitigate community transmission of SARS-CoV-2: protocol for a public health intervention with a nested prospective cohort study.

BACKGROUND: The COVID-19 pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to evolve as a global health crisis. Although highly effective vaccines have been developed, non-pharmaceutical interventions remain critical to controlling disease transmission. One such intervention-rapid, at-home antigen self-testing-can ease the burden associated with facility-based testing programs and improve testing access in high-risk communities. However, its impact on SARS-CoV-2 community transmission has yet to be definitively evaluated, and the socio-behavioral aspects of testing in underserved populations remain unknown. METHODS: As part of the Rapid Acceleration of Diagnostics-Underserved Populations (RADx-UP) program funded by the National Institutes of Health, we are implementing a public health intervention titled "Say Yes! COVID Test" (SYCT) involving at-home self-testing using a SARS-CoV-2 rapid antigen assay in North Carolina (Greenville, Pitt County) and Tennessee (Chattanooga City, Hamilton County). The intervention is supported by a multifaceted communication and community engagement strategy to ensure widespread awareness and uptake, particularly in marginalized communities. Participants receive test kits either through online orders or via local community distribution partners. To assess the impact of this intervention on SARS-CoV-2 transmission, we will conduct a non-randomized, ecological study using community-level outcomes. Specifically, we will evaluate trends in SARS-CoV-2 cases and hospitalizations, SARS-CoV-2 viral load in wastewater, and population mobility in each community before, during, and after the SYCT intervention. Individuals who choose to participate in SYCT will also have the option to enroll in an embedded prospective cohort substudy gathering participant-level data to evaluate behavioral determinants of at-home self-testing and socio-behavioral mechanisms of SARS-CoV-2 community transmission. DISCUSSION: This is the first large-scale, public health intervention implementing rapid, at-home SARS-CoV-2 self-testing in the United States. The program consists of a novel combination of an at-home testing program, a broad communications and community engagement strategy, an ecological study to assess impact, and a research substudy of the behavioral aspects of testing. The findings from the SYCT project will provide insights into innovative methods to mitigate viral transmission, advance the science of public health communications and community engagement, and evaluate emerging, novel assessments of community transmission of disease.

Construction of a Sequenceable Protein Mimetic Peptide Library with a True 3D Diversifiable Chemical Space.

We present here a library of protein mimetic bicyclic peptides. These nanosized structures exhibit rigid backbones and spatially diversifiable side chains. They present modular amino acids on all three linkages, providing access to a true 3D diversifiable chemical space. These peptides are synthesized through a Cu-catalyzed click reaction and a Ru-catalyzed ring-closing metathesis reaction. Their bicyclic topology can be reduced to a linear one, using Edman degradation and Pd-catalyzed deallylation reactions. The linearization approaches allow de novo sequencing through mass spectrometry methods. We demonstrate the function of a particular peptide that was identified through a high throughput screening against the E363-R378 epitope on the intrinsically disordered c-Myc oncoprotein. Intracellular delivery of this peptide could interfere with the c-Myc-mediated transcription and inhibit proliferation in a human glioblastoma cell line.

Preperitoneal balloon tamponade for lethal closed retroperitoneal pelvic hemorrhage in a swine model: A comparable and minimally invasive alternative to open pre-peritoneal pelvic packing.

BACKGROUND: The management of massive pelvic fracture-associated hemorrhage is extremely challenging, particularly in the unstable patient. We sought to characterize and compare the efficacy of a minimally invasive preperitoneal balloon technique (MIB) to standard open packing. METHODS: Twenty-six swine were randomized to control (C), open preperitoneal packing technique (OP), and MIB groups. A closed extraperitoneal iliac vascular injury followed by intervention + resuscitation over a 120-minute OP and MIB efficacy was assessed by procedure time, hemodynamics, extraperitoneal tamponade pressures (ETPs), blood loss, and survival. Angiography was performed in select animals, and ETPs were also measured in humans undergoing MIB placement for an elective procedure. RESULTS: Baseline parameters (mean arterial pressure [MAP] 29, 38, and 38 mm Hg; cardiac index [CI] 3.5, 3.8, and 4.2; and EPTs 5, 4, and 5 mm Hg) were similar among C, OP, and MIB groups, respectively (all p's > 0.05). The OP and MIB groups had markedly improved MAP and CI versus C. MIB generated significantly higher ETP (28 vs 17 mm Hg), was faster to deploy (164 vs 497 seconds), and had lower total blood loss versus OP (0.7 vs 1.2 L, all p's < 0.05). OP and MIB had equivalent survival times that were significantly improved versus C (91 and 116 vs 43 minutes, p < 0.05). Survival to 2 hours was 80% with OP versus 100% in the MIB group. Angiography showed no active extravasation in both study groups, but controlled partial deflation of the MIB allowed easy visualization of extravasation. Minimally invasive preperitoneal balloon inflation in five human subjects demonstrated a significant increase in mean ETP from 2.4 to 31 mm Hg (p < 0.01). CONCLUSION: Minimally invasive preperitoneal balloon tamponade was as effective as OP in improving hemodynamics and prolonging survival times, and performed superiorly to OP in time to placement, blood loss, and generation of tamponade pressures. The MIB allows for controlled deflation and reinflation to facilitate angiographic interventions, and may represent a promising new bedside intervention in this patient population.

Ethmoid pneumocele presenting with exophthalmos 15 years after endoscopic sinus surgery.

INTRODUCTION: A pneumocele is an abnormal dilation of an air-containing sinus beyond the normal margins of bone, with associated bony thinning. A delayed ethmoid pneumocele after sinus surgery has not previously been reported. METHODS: A case report of a patient with a delayed ethmoid pneumocele after sinus surgery. The diagnostic workup, operative approach, and postoperative results were evaluated. RESULTS: A 57-year-old female with a history of endoscopic sinus surgery 15 years prior presented with right eye proptosis and severe orbital and facial pressure. A maxillofacial computed tomography showed a markedly expanded air-filled right anterior ethmoid space with a dehiscent lamina papyracea, consistent with a pneumocele. Marsupialization of the pneumocele as well as a revision ethmoidectomy were performed, with a visible return of the orbital contents to a more natural position. The patient experienced worsened diplopia immediately postoperatively that resolved within two weeks. CONCLUSIONS: This case demonstrates that a pneumocele can present even years after endoscopic sinus surgery, and acute but temporary development or worsening of diplopia can result from surgical decompression of the pneumocele as the eye returns to its natural position.

Hydrogen bond residue positioning in the 599-611 loop of thimet oligopeptidase is required for substrate selection.

Thimet oligopeptidase (EC 3.4.24.15) is a zinc(II) endopeptidase implicated in the processing of numerous physiological peptides. Although its role in selecting and processing peptides is not fully understood, it is believed that flexible loop regions lining the substrate-binding site allow the enzyme to conform to substrates of varying structure. This study describes mutant forms of thimet oligopeptidase in which Gly or Tyr residues in the 599-611 loop region were replaced, individually and in combination, to elucidate the mechanism of substrate selection by this enzyme. Decreases in k(cat) observed on mutation of Tyr605 and Tyr612 demonstrate that these residues contribute to the efficient cleavage of most substrates. Modeling studies showing that a hinge-bend movement brings both Tyr612 and Tyr605 within hydrogen bond distance of the cleaved peptide bond supports this role. Thus, molecular modeling studies support a key role in transition state stabilization of this enzyme by Tyr605. Interestingly, kinetic parameters show that a bradykinin derivative is processed distinctly from the other substrates tested, suggesting that an alternative catalytic mechanism may be employed for this particular substrate. The data demonstrate that neither Tyr605 nor Tyr612 is necessary for the hydrolysis of this substrate. Relative to other substrates, the bradykinin derivative is also unaffected by Gly mutations in the loop. This distinction suggests that the role of Gly residues in the loop is to properly orientate these Tyr residues in order to accommodate varying substrate structures. This also opens up the possibility that certain substrates may be cleaved by an open form of the enzyme.