Heating decoys to mimic thermal signatures of live animals for drones.

Thermal sensors mounted on drones (unoccupied aircraft systems) are popular and effective tools for monitoring cryptic animal species, although few studies have quantified sampling error of animal counts from thermal images. Using decoys is one effective strategy to quantify bias and count accuracy; however, plastic decoys do not mimic thermal signatures of representative species. Our objective was to produce heat signatures in animal decoys to realistically match thermal images of live animals obtained from a drone-based sensor. We tested commercially available methods to heat plastic decoys of three different size classes, including chemical foot warmers, manually heated water, electric socks, pad, or blanket, and mini and small electric space heaters. We used criteria in two categories, 1) external temperature differences from ambient temperatures (ambient difference) and 2) color bins from a palette in thermal images obtained from a drone near the ground and in the air, to determine if heated decoys adequately matched respective live animals in four body regions. Three methods achieved similar thermal signatures to live animals for three to four body regions in external temperatures and predominantly matched the corresponding yellow color bins in thermal drone images from the ground and in the air. Pigeon decoys were best and most consistently heated with three-foot warmers. Goose and deer decoys were best heated by mini and small space heaters, respectively, in their body cavities, with a heated sock in the head of the goose decoy. The materials and equipment for our best heating methods were relatively inexpensive, commercially available items that provide sustained heat and could be adapted to various shapes and sizes for a wide range of avian and mammalian species. Our heating methods could be used in future studies to quantify bias and validate methodologies for drone surveys of animals with thermal sensors.•We determined optimal heating methods for plastic animal decoys with inexpensive and commercially available equipment to mimic thermal signatures of live animals.•Methods could be used to quantify bias and improve thermal surveys of animals with drones in future studies.

Evaluation of the Therapeutic Potential of Traditionally-Used Natural Plant Extracts to Inhibit Proliferation of a HeLa Cell Cancer Line and Replication of Human Respiratory Syncytial Virus (hRSV).

Traditional approaches employing natural plant products to treat a wide array of ailments have been documented and described for thousands of years. However, there remains limited scientific study of the therapeutic potential or effectiveness of ethnobotanical applications. Increases in the incidence of cancer and emerging infectious diseases demonstrate a growing need for advances in the development of therapeutic options. In this study, we evaluate the therapeutic potential of aqueous extracts prepared from four plants, purple aster (Symphyotrichum novae-angliae (L.) Nemsom), common sage (Salvia lyrata (L.)), northern spicebush (Lindera benzoin (L.) Blume), and lamb's ear (Stachys byzantina (K.) Koch)) traditionally used in Native American medicine in Indiana, USA. Using a combination of cytotoxicity assays, immunofluorescence microscopy, and antiviral assays, we found that sage and spicebush extracts exhibit cytotoxic and antiproliferative effects on HeLa cell proliferation and that sage, spicebush, and aster extracts were capable of significantly inhibiting human respiratory syncytial virus (hRSV), a major respiratory pathogen of infants and the elderly. Chemical analysis of the four extracts identified four major compounds which were subsequently evaluated to identify the responsible constituents in the extracts. While none of the identified compounds were shown to induce significant impacts on HeLa cell proliferation, two of the compounds, (1S)-(-)-Borneol and 5-(hydroxymethyl)-furfural, identified in sage and spicebush, respectively, were shown to have antiviral activities. Our data suggest that several of the extracts tested exhibited either anti-proliferative or antiviral activity supporting future further analysis.

Cryopreserving the intact intervertebral disc without compromising viability.

Background: Tissue cryopreservation requires saturation of the structure with cryoprotectants (CPAs) that are also toxic to cells within a short timeframe unless frozen. The race between CPA delivery and cell death is the main barrier to realizing transplantation banks that can indefinitely preserve tissues and organs. Unrealistic cost and urgency leaves less life-threatening ailments unable to capitalize on traditional organ transplantation systems that immediately match and transport unfrozen organs. For instance, human intervertebral discs (IVD) could be transplanted to treat back pain or used as ex vivo models for studying regenerative therapies, but both face logistical hurdles in organ acquisition and transport. Here we aimed to overcome those challenges by cryopreserving intact IVDs using compressive loading and swelling to accelerate CPA delivery. Methods: CPAs were tested on bovine nucleus pulposus cells to determine the least cytotoxic solution. Capitalizing on our CPAs Computed Tomography (CT) contrast enhancement, we imaged and quantified saturation time in intact bovine IVDs under different conditions in a bioreactor. Finally, the entire protocol was tested, including 1 week of frozen storage, to confirm tissue viability in multiple IVD regions after thawing. Results: Results showed cryopreserving medium containing dimethyl sulfoxide and ethylene glycol gave over 7.5 h before cytotoxicity. While non-loaded IVDs required over 3 days to fully saturate, a dynamic loading protocol followed by CPA addition and free-swelling decreased saturation time to <5 h. After cryopreserving IVDs for 1 week with the optimized CPA and permeation method, all IVD regions had 85% cell viability, not significantly different from fresh unfrozen controls. Conclusions: This study created a novel solution to a roadblock in IVD research and development. Using post-compression swelling CPA can be delivered to an intact IVD over 20× more quickly than previous methods, enabling cryopreservation of the IVD with no detectable loss in cell viability.

Going rogue: mechanisms, regulation, and roles of mutationally activated Gα in human cancer.

G protein-coupled receptors (GPCRs) couple to heterotrimeric G proteins, comprised of α and ßγ subunits, to convert extracellular signals into activation of intracellular signaling pathways. Canonically, GPCR-mediated activation results in the exchange of GDP for GTP on Gα and the dissociation of Gα-GTP and Gßγ, both of which can regulate a variety of signaling pathways. Hydrolysis of bound GTP by Gα returns the protein to Gα-GDP and allows reassociation with Gßγ to re-form the inactive heterotrimer. Naturally occurring mutations in Gα have been found at conserved glutamine and arginine amino acids that disrupt the canonical G protein cycle by inhibiting GTP hydrolysis, rendering these mutants constitutively active. Interestingly, these dysregulated Gα mutants are found in many different cancers due to their ability to sustain aberrant signaling without a need for activation by GPCRs. This review will highlight an increased recognition of the prevalence of such constitutively activating Gα mutations in cancers and the signaling pathways activated. In addition, we will discuss new knowledge regarding how these constitutively active Gα are regulated, how different mutations are biochemically distinct, and how mutationally activated Gα are unique compared to GPCR-activated Gα. Lastly, we will discuss recent progress in developing inhibitors directly targeting constitutively active Gα mutants. Significance Statement Constitutively activating mutations in G protein α subunits (Gα) widely occur in and contribute to the development of many human cancers. To develop ways to inhibit dysregulated, oncogenic signaling by these mutant Gα, it is crucial to better understand mechanisms that lead to constitutive Gα activation and unique mechanisms that regulate mutationally activated Gα in cells. The prevalence of activating mutations in Gα in various cancers make Gα proteins compelling targets for the development of therapeutics.

Brain-penetrant complement inhibition mitigates neurodegeneration in an Alzheimer's disease mouse model.

Complement activation is implicated in driving brain inflammation, self-cell damage and progression of injury in Alzheimer's disease and other neurodegenerative diseases. Here, we investigate the impact of brain delivery of a complement-blocking antibody on neurodegeneration in an Alzheimer's mouse model. We engineered a brain-penetrant recombinant antibody targeting the pro-inflammatory membrane attack complex. Systemic administration of this antibody in APPNL-G-F mice reduced brain levels of complement activation products, demonstrating successful brain entry and target engagement. Prolonged treatment decreased synapse loss, amyloid burden and brain inflammatory cytokine levels, concomitant with cognitive improvement compared to controls. These results underscore the potential of brain-penetrant complement-inhibiting drugs as promising therapeutics, targeting downstream of amyloid plaques in Alzheimer's disease.

Triceps-to-Biceps Tendon Transfer Technique for Restoration of Elbow Flexion in Adult Brachial Plexus Injury.

Restoration of elbow flexion is a priority in treating adult traumatic brachial plexus injuries. A tendon transfer is an ideal option for patients not candidates for reconstructive nerve surgery or free-functioning muscle transfer. For patients with a partial brachial plexus injury or a pan plexus injury with adequate recovered triceps function and loss of elbow flexion, a triceps-to-biceps tendon transfer is a nonmicrosurgical option to restore elbow flexion. The technique of triceps-to-biceps transfer in which the complete triceps tendon is transferred laterally, secured lateral to the radial tuberosity, and reinforced with suture to the biceps tendon is described.

Dysregulation of baseline and learning-dependent protein degradation in the aged hippocampus.

The ubiquitin-proteasome system (UPS) controls the majority of protein degradation in cells and dysregulation of the UPS has been implicated in the pathophysiology of numerous neurodegenerative disorders, including Alzheimer's disease. Further, strong evidence supports a critical role for the UPS in synaptic plasticity and memory formation. However, while proteasome function is known to decrease broadly in the brain across the lifespan, whether it changes in the hippocampus, a region critical for memory storage and among the first impacted in Alzheimer's disease, at rest and following learning in the aged brain remains unknown. Further, which proteins have altered targeting for protein degradation in the aged hippocampus has yet to be explored and whether learning in advanced age interacts with changes in ubiquitin-proteasome function across the lifespan remains unknown. Here, using proteasome activity assays and unbiased proteomic analyses, we report age-dependent changes in proteasome activity and degradation-specific K48 polyubiquitin protein targeting in the hippocampus and retrosplenial cortex of male and female rats across the lifespan. In the hippocampus, the targets of altered protein degradation were involved in transcription and astrocyte structure or G-protein and Interferon signaling in males and females, respectively. Importantly, we found that contextual fear conditioning led to an increase in proteasome activity and K48 polyubiquitin protein targeting in the hippocampus of aged male rats, a result in direct contrast to what was previously reported in young adult animals. Together, these data suggest that changes in protein degradation in the hippocampus across the lifespan may be contributing to age-related memory loss.

The Study of the Epidemiology of Pediatric Hypertension Registry (SUPERHERO): Rationale and Methods.

Despite increasing prevalence of hypertension in youth and high adult cardiovascular mortality rates, the long-term consequences of youth-onset hypertension remain unknown. This is due to limitations of prior research such as small sample sizes, reliance on manual record review, and limited analytic methods that did not address major biases. The Study of the Epidemiology of Pediatric Hypertension (SUPERHERO) is a multisite retrospective Registry of youth evaluated by subspecialists for hypertension disorders. Sites obtain harmonized electronic health record data using standardized biomedical informatics scripts validated with randomized manual record review. Inclusion criteria are index visit for International Classification of Diseases Diagnostic Codes, 10th Revision (ICD-10 code)-defined hypertension disorder ≥January 1, 2015 and age <19 years. We exclude patients with ICD-10 code-defined pregnancy, kidney failure on dialysis, or kidney transplantation. Data include demographics, anthropomorphics, U.S. Census Bureau tract, histories, blood pressure, ICD-10 codes, medications, laboratory and imaging results, and ambulatory blood pressure. SUPERHERO leverages expertise in epidemiology, statistics, clinical care, and biomedical informatics to create the largest and most diverse registry of youth with newly diagnosed hypertension disorders. SUPERHERO's goals are to (i) reduce CVD burden across the life course and (ii) establish gold-standard biomedical informatics methods for youth with hypertension disorders.

Lower Prevalence of Asymptomatic Alzheimer's Disease Among Healthy African Americans.

OBJECTIVE: Alzheimer's disease (AD) is believed to be more common in African Americans (AA), but biomarker studies in AA populations are limited. This report represents the largest study to date examining cerebrospinal fluid AD biomarkers in AA individuals. METHODS: We analyzed 3,006 cerebrospinal fluid samples from controls, AD cases, and non-AD cases, including 495 (16.5%) self-identified black/AA and 2,456 (81.7%) white/European individuals using cutoffs derived from the Alzheimer's Disease Neuroimaging Initiative, and using a data-driven multivariate Gaussian mixture of regressions. RESULTS: Distinct effects of race were found in different groups. Total Tauand phospho181-Tau were lower among AA individuals in all groups (p < 0.0001), and Aß42 was markedly lower in AA controls compared with white controls (p < 0.0001). Gaussian mixture of regressions modeling of cerebrospinal fluid distributions incorporating adjustments for covariates revealed coefficient estimates for AA race comparable with 2-decade change in age. Using Alzheimer's Disease Neuroimaging Initiative cutoffs, fewer AA controls were classified as biomarker-positive asymptomatic AD (8.0% vs 13.4%). After adjusting for covariates, our Gaussian mixture of regressions model reduced this difference, but continued to predict lower prevalence of asymptomatic AD among AA controls (9.3% vs 13.5%). INTERPRETATION: Although the risk of dementia is higher, data-driven modeling indicates lower frequency of asymptomatic AD in AA controls, suggesting that dementia among AA populations may not be driven by higher rates of AD. ANN NEUROL 2024;96:463-475.

Provider-to-provider telemedicine for sepsis is used less frequently in communities with high social vulnerability.

PURPOSE: Sepsis disproportionately affects patients in rural and socially vulnerable communities. A promising strategy to address this disparity is provider-to-provider emergency department (ED)-based telehealth consultation (tele-ED). The objective of this study was to determine if county-level social vulnerability index (SVI) was associated with tele-ED use for sepsis and, if so, which SVI elements were most strongly associated. METHODS: We used data from the TELEmedicine as a Virtual Intervention for Sepsis in Rural Emergency Department study. The primary exposures were SVI aggregate and component scores. We used multivariable generalized estimating equations to model the association between SVI and tele-ED use. FINDINGS: Our study cohort included 1191 patients treated in 23 Midwestern rural EDs between August 2016 and June 2019, of whom 326 (27.4%) were treated with tele-ED. Providers in counties with a high SVI were less likely to use tele-ED (adjusted odds ratio [aOR] = 0.51, 95% confidence interval [CI] 0.31‒0.87), an effect principally attributable to the housing type and transportation component of SVI (aOR = 0.44, 95% CI 0.22-0.89). Providers who treated fewer sepsis patients (1‒10 vs. 31+ over study period) and therefore may have been less experienced in sepsis care, were more likely to activate tele-ED (aOR = 3.91, 95% CI 2.08‒7.38). CONCLUSIONS: Tele-ED use for sepsis was lower in socially vulnerable counties and higher among providers who treated fewer sepsis patients. These findings suggest that while tele-ED increases access to specialized care, it may not completely ameliorate sepsis disparities due to its less frequent use in socially vulnerable communities.

Impact of the COVID-19 pandemic on the productivity and career prospects of musculoskeletal researchers.

Academic researchers faced a multitude of challenges posed by the COVID-19 pandemic, including widespread shelter-in-place orders, workplace closures, and cessation of in-person meetings and laboratory activities. The extent to which these challenges impacted musculoskeletal researchers, specifically, is unknown. We developed an anonymous web-based survey to determine the pandemic's impact on research productivity and career prospects among musculoskeletal research trainees and faculty. There were 116 musculoskeletal (MSK) researchers with varying demographic backgrounds who completed the survey. Of respondents, 48.3% (n = 56) believed that musculoskeletal funding opportunities decreased because of COVID-19, with faculty members more likely to hold this belief compared to nonfaculty researchers (p = 0.008). Amongst MSK researchers, 88.8% (n = 103) reported research activity was limited by COVID-19, and 92.2% (n = 107) of researchers reported their research was not able to be refocused on COVID-19-related topics, with basic science researchers less likely to be able to refocus their research compared to clinical researchers (p = 0.030). Additionally, 47.4% (n = 55) reported a decrease in manuscript submissions since the onset of the pandemic. Amongst 51 trainee researchers, 62.8% (n = 32) reported a decrease in job satisfaction directly attributable to the COVID-19 pandemic. In summary, study findings indicated that MSK researchers struggled to overcome challenges imposed by the pandemic, reporting declines in funding opportunities, research productivity, and manuscript submission. Trainee researchers experienced significant disruptions to critical research activities and worsening job satisfaction. Our findings motivate future efforts to support trainees in developing their careers and target the recovery of MSK research from the pandemic stall.

Reproductive Ageing: Current insights and a potential role of NAD in the reproductive health of aging fathers and their children.

In brief: In light of the increasing age of first-time fathers, this article summarizes the current scientific knowledge base on reproductive aging in the male, including sperm quality and health impacts for the offspring. The emerging role of NAD decline in reproductive aging is highlighted. Abstract: Over the past decades, the age of first-time fathers has been steadily increasing due to socio-economic pressures. While general mechanisms of aging are subject to intensive research, male reproductive aging has remained an understudied area, and the effects of increased age on the male reproductive system are still only poorly understood, despite new insights into the potential dire consequences of advanced paternal age for the health of their progeny. There is also growing evidence that reproductive aging is linked to overall health in men, but this review mainly focuses on pathophysiological consequences of old age in men, such as low sperm count and diminished sperm genetic integrity, with an emphasis on mechanisms underlying reproductive aging. The steady decline of NAD levels observed in aging men represents one of the emerging concepts in that regard. Because it offers some mechanistic rationale explaining the effects of old age on the male reproductive system, some of the NAD-dependent functions in male reproduction are briefly outlined in this review. The overview also provides many questions that remain open about the basic science of male reproductive aging.

The complement system in neurodegenerative diseases.

Complement is an important component of innate immune defence against pathogens and crucial for efficient immune complex disposal. These core protective activities are dependent in large part on properly regulated complement-mediated inflammation. Dysregulated complement activation, often driven by persistence of activating triggers, is a cause of pathological inflammation in numerous diseases, including neurological diseases. Increasingly, this has become apparent not only in well-recognized neuroinflammatory diseases like multiple sclerosis but also in neurodegenerative and neuropsychiatric diseases where inflammation was previously either ignored or dismissed as a secondary event. There is now a large and rapidly growing body of evidence implicating complement in neurological diseases that cannot be comprehensively addressed in a brief review. Here, we will focus on neurodegenerative diseases, including not only the 'classical' neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease, but also two other neurological diseases where neurodegeneration is a neglected feature and complement is implicated, namely, schizophrenia, a neurodevelopmental disorder with many mechanistic features of neurodegeneration, and multiple sclerosis, a demyelinating disorder where neurodegeneration is a major cause of progressive decline. We will discuss the evidence implicating complement as a driver of pathology in these diverse diseases and address briefly the potential and pitfalls of anti-complement drug therapy for neurodegenerative diseases.

Hospital Variation in Epinephrine Administration Before Defibrillation for Cardiac Arrest Due to Shockable Rhythm.

OBJECTIVES: Contrary to advanced cardiac life support guidelines that recommend immediate defibrillation for shockable in-hospital cardiac arrest (IHCA), epinephrine administration before first defibrillation is common and associated with lower survival at a "patient-level." Whether this practice varies across hospitals and its association with "hospital-level" IHCA survival remains unknown. The purpose of this study was to determine hospital variation in rates of epinephrine administration before defibrillation for shockable IHCA and its association with IHCA survival. DESIGN: Observational cohort study. SETTING: Five hundred thirteen hospitals participating in the Get With The Guidelines Resuscitation Registry. PATIENTS: A total of 37,668 adult patients with IHCA due to an initial shockable rhythm from 2000 to 2019. INTERVENTIONS: Epinephrine before first defibrillation. MEASUREMENTS AND MAIN RESULTS: Using multivariable hierarchical regression, we examined hospital variation in epinephrine administration before first defibrillation and its association with hospital-level rates of risk-adjusted survival. The median hospital rate of epinephrine administration before defibrillation was 18.8%, with large variation across sites (range, 0-68.8%; median odds ratio: 1.54; 95% CI, 1.47-1.61). Major teaching status and annual IHCA volume were associated with hospital rate of epinephrine administration before defibrillation. Compared with hospitals with the lowest rate of epinephrine administration before defibrillation (Q1), there was a stepwise decline in risk-adjusted survival at hospitals with higher rates of epinephrine administration before defibrillation (Q1: 44.3%, Q2: 43.4%; Q3: 41.9%; Q4: 40.3%; p for trend < 0.001). CONCLUSIONS: Administration of epinephrine before defibrillation in shockable IHCA is common and varies markedly across U.S. hospitals. Hospital rates of epinephrine administration before defibrillation were associated with a significant stepwise decrease in hospital rates of risk-adjusted survival. Efforts to prioritize immediate defibrillation for patients with shockable IHCA and avoid early epinephrine administration are urgently needed.

Insights into Factors Affecting Ethylene-Vinyl Acetate Copolymer Crystallinity in Islatravir Implant.

Islatravir, a highly potent nucleoside reverse transcriptase translocation inhibitor (NRTTI) for the treatment of HIV, has great potential to be formulated as ethylene-vinyl acetate (EVA) copolymer-based implants via hot melt extrusion. The crystallinity of EVA determines its physical and rheological properties and may impact the drug-eluting implant performance. Herein, we describe the systematic analysis of factors affecting the EVA crystallinity in islatravir implants. Differential scanning calorimetry (DSC) on EVA and solid-state NMR revealed drug loading promoted EVA crystallization, whereas BaSO4 loading had negligible impact on EVA crystallinity. The sterilization through γ-irradiation appeared to significantly impact the EVA crystallinity and surface characteristics of the implants. Furthermore, DSC analysis of thin implant slices prepared with an ultramicrotome indicated that the surface layer of the implant was more crystalline than the core. These findings provide critical insights into factors affecting the crystallinity, mechanical properties, and physicochemical properties of the EVA polymer matrix of extruded islatravir implants.

IKK2 controls the inflammatory potential of tissue-resident regulatory T cells in a murine gain of function model.

Loss-of-function mutations have provided crucial insights into the immunoregulatory actions of Foxp3+ regulatory T cells (Tregs). By contrast, we know very little about the consequences of defects that amplify aspects of Treg function or differentiation. Here we show that mice heterozygous for an Ikbkb gain-of-function mutation develop psoriasis. Doubling the gene dose (IkbkbGoF/GoF) results in dactylitis, spondylitis, and characteristic nail changes, which are features of psoriatic arthritis. IkbkbGoF mice exhibit a selective expansion of Foxp3 + CD25+ Tregs of which a subset express IL-17. These modified Tregs are enriched in both inflamed tissues, blood and spleen, and their transfer is sufficient to induce disease without conventional T cells. Single-cell transcriptional and phenotyping analyses of isolated Tregs reveal expansion of non-lymphoid tissue (tissue-resident) Tregs expressing Th17-related genes, Helios, tissue-resident markers including CD103 and CD69, and a prominent NF-κB transcriptome. Thus, IKK2 regulates tissue-resident Treg differentiation, and overactivity drives dose-dependent skin and systemic inflammation.

The burden of skin and soft tissue, bone and joint infections in an Australian cohort of people who inject drugs.

INTRODUCTION: There are currently limited data regarding the clinical and economic significance of skin and soft tissue infections (SSTI) and bone and joint infections in Australian people who inject drugs (PWID). METHODS: Retrospective cohort study in adult PWID admitted to Monash Health, a large heath care network with six hospitals in Victoria, Australia. Inpatients were identified using administrative datasets and International Classification of Disease (ICD-10) coding for specific infection-related conditions. Cost analysis was based on mean ward, intensive care and hospital-in-the-home (HITH) lengths of stay. Spinal infections and endocarditis were excluded as part of previous studies. RESULTS: A total of 185 PWID (61 female, 124 male, median age 37) meeting the study criteria were admitted to Monash Health between January 2010 and January 2021. Admitting diagnoses included 78 skin abscesses, 80 cellulitis, 17 septic arthritis, 4 osteomyelitis, 3 thrombophlebitis and 1 each of necrotising fasciitis, vasculitis and myositis. Pain (87.5%) and swelling (75.1%) were the most common presenting complaints. Opioids (67.4%) and methamphetamine (37.5%) were the most common primary drugs injected. Almost half (46.5%) of patients had concurrent active hepatitis C (HCV) infection on admission. Hepatitis B (HBV) and Human Immunodeficiency Virus (HIV) were uncommon. The most significant causative organism was methicillin-susceptible Staphylococcus aureus (24.9%). In 40.0% (74/185) no organism was identified. Patients required a median acute hospital stay of 5 days (2-51 days). There were 15 patients admitted to the intensive care unit (ICU) with median duration 2 days. PICC line insertion for antibiotics was required in 16.8% of patients, while 51.4% required surgical intervention. Median duration of both oral and IV antibiotic therapy was 11 days. Almost half (48.6%) of patients were enrolled in an opioid maintenance program on discharge. Average estimated expenditure was AUD $16, 528 per admission. CONCLUSION: Skin and soft tissue and joint infections are a major cause of morbidity for PWID. Admission to hospital provides opportunistic involvement of addiction specialty services.

Complement dysregulation is a prevalent and therapeutically amenable feature of long COVID.

BACKGROUND: Long COVID encompasses a heterogeneous set of ongoing symptoms that affect many individuals after recovery from infection with SARS-CoV-2. The underlying biological mechanisms nonetheless remain obscure, precluding accurate diagnosis and effective intervention. Complement dysregulation is a hallmark of acute COVID-19 but has not been investigated as a potential determinant of long COVID. METHODS: We quantified a series of complement proteins, including markers of activation and regulation, in plasma samples from healthy convalescent individuals with a confirmed history of infection with SARS-CoV-2 and age/ethnicity/sex/infection/vaccine-matched patients with long COVID. FINDINGS: Markers of classical (C1s-C1INH complex), alternative (Ba, iC3b), and terminal pathway (C5a, TCC) activation were significantly elevated in patients with long COVID. These markers in combination had a receiver operating characteristic predictive power of 0.794. Other complement proteins and regulators were also quantitatively different between healthy convalescent individuals and patients with long COVID. Generalized linear modeling further revealed that a clinically tractable combination of just four of these markers, namely the activation fragments iC3b, TCC, Ba, and C5a, had a predictive power of 0.785. CONCLUSIONS: These findings suggest that complement biomarkers could facilitate the diagnosis of long COVID and further suggest that currently available inhibitors of complement activation could be used to treat long COVID. FUNDING: This work was funded by the National Institute for Health Research (COV-LT2-0041), the PolyBio Research Foundation, and the UK Dementia Research Institute.

Multi-Material Volumetric Additive Manufacturing of Hydrogels using Gelatin as a Sacrificial Network and 3D Suspension Bath.

Volumetric additive manufacturing (VAM) is an emerging layerless method for the rapid processing of reactive resins into 3D structures, where printing is much faster (seconds) than other lithography and direct ink writing methods (minutes to hours). As a vial of resin rotates in the VAM process, patterned light exposure defines a 3D object and then resin that has not undergone gelation can be washed away. Despite the promise of VAM, there are challenges with the printing of soft hydrogel materials from non-viscous precursors, including multi-material constructs. To address this, sacrificial gelatin is used to modulate resin viscosity to support the cytocompatible VAM printing of macromers based on poly(ethylene glycol) (PEG), hyaluronic acid (HA), and polyacrylamide (PA). After printing, gelatin is removed by washing at an elevated temperature. To print multi-material constructs, the gelatin-containing resin is used as a shear-yielding suspension bath (including HA to further modulate bath properties) where ink can be extruded into the bath to define a multi-material resin that can then be processed with VAM into a defined object. Multi-material constructs of methacrylated HA (MeHA) and gelatin methacrylamide (GelMA) are printed (as proof-of-concept) with encapsulated mesenchymal stromal cells (MSCs), where the local hydrogel properties guide cell spreading behavior with culture.