Mitochondria-Targeted Fluorescent Nanoparticles with Large Stokes Shift for Long-Term BioImaging.

Mitochondria (MITO) play a significant role in various physiological processes and are a key organelle associated with different human diseases including cancer, diabetes mellitus, atherosclerosis, Alzheimer's disease, etc. Thus, detecting the activity of MITO in real time is becoming more and more important. Herein, a novel class of amphiphilic aggregation-induced emission (AIE) active probe fluorescence (AC-QC nanoparticles) based on a quinoxalinone scaffold was developed for imaging MITO. AC-QC nanoparticles possess an excellent ability to monitor MITO in real-time. This probe demonstrated the following advantages: (1) lower cytotoxicity; (2) superior photostability; and (3) good performance in long-term imaging in vitro. Each result of these indicates that self-assembled AC-QC nanoparticles can be used as effective and promising MITO-targeted fluorescent probes.

Switch-on Fluorescence Analysis of Protease Activity with the Assistance of a Nickel Ion-Nitrilotriacetic Acid-Conjugated Magnetic Nanoparticle.

Heterogeneous protease biosensors show high sensitivity and selectivity but usually require the immobilization of peptide substrates on a solid interface. Such methods exhibit the disadvantages of complex immobilization steps and low enzymatic efficiency induced by steric hindrance. In this work, we proposed an immobilization-free strategy for protease detection with high simplicity, sensitivity and selectivity. Specifically, a single-labeled peptide with oligohistidine-tag (His-tag) was designed as the protease substrate, which can be captured by a nickel ion-nitrilotriacetic acid (Ni-NTA)-conjugated magnetic nanoparticle (MNP) through the coordination interaction between His-tag and Ni-NTA. When the peptide was digested by protease in a homogeneous solution, the signal-labeled segment was released from the substrate. The unreacted peptide substrates could be removed by Ni-NTA-MNP, and the released segments remained in solution to emit strong fluorescence. The method was used to determine protease of caspase-3 with a low detection limit (4 pg/mL). By changing the peptide sequence and signal reporters, the proposal could be used to develop novel homogeneous biosensors for the detection of other proteases.

The prognostic impact of monocyte fluorescence, immunosuppressive monocytes and peripheral blood immune cell numbers in HIV-associated Diffuse Large B-cell Lymphoma.

INTRODUCTION: Diffuse large B-cell lymphoma (DLBCL) is a high grade non-Hodgkin lymphoma which is common among immunodeficient people. Derangements of peripheral blood immune cells have been described to have a prognostic impact in DLBCL in high income countries, including a monocytosis, the ratios of lymphocytes to both monocytes (L:M) and neutrophils (N:L), as well as the numbers of regulatory T-cells (Tregs) and immunosuppressive monocytes (HLA-DRlow monos). To date, the impact of these variables has not been assessed in the setting of HIV-associated DLBCL (HIV-DLBCL), which is among the most common malignancies seen in people living with HIV. In this study, we assessed these factors in a cohort of South African patients with DLBCL and a high HIV-seropositivity-rate. In addition, we evaluated the prognostic value of monocyte activation (as reflected by monocyte fluorescence (MO-Y) on a Sysmex haematology analyser). This parameter has to date not been assessed in the setting of DLBCL. METHODS: A full blood count and differential count as well as flow cytometry for HLA-DRlow monocyte and Treg enumeration were performed in patients with incident DLBCL referred to the Chris Hani Baragwanath Academic Hospital in Johannesburg, South Africa between November 2019 and May 2022. Additional clinical and laboratory data were recorded from the patient charts and laboratory information system. RESULTS: Seventy-six patients were included, of whom 81.3% were people living with HIV with a median CD4 count of 148 cells/ul. Most patients had advanced stage disease (74.8%) and were predominantly treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP)-based chemotherapy (without Rituximab). At a median follow-up period of 19 months, the median survival time was 3.5 months, with a 12-month survival rate of 27.0%. All of the immune-cell-related variables (with the exception of the CD4 count) were similar between the people living with HIV and the HIV-negative individuals. In contrast to previous studies, a high monocyte count, the L:M and increased numbers of HLA-DRlow monocytes were not significantly associated with survival in HIV-DLBCL, while a neutrophilia (>8 x 109/L), the N:L (>6:1), high numbers of Tregs (≥5.17% of CD4s) and lymphopenia (<1.3 x 109/L) were. In addition, increased monocyte fluorescence (MO-Y >115.5) was associated with superior outcomes, which we speculate to reflect a more robust antitumour immune response among individuals with high levels of monocyte activation. On Cox Proportional hazard analysis, immune-cell factors independently associated with survival included a CD4 count <150 cells/ul and a neutrophilia. CONCLUSION: The monocyte count, L:M and the number of HLA-DRlow monos are not strong prognostic indicators in HIV-DLBCL, while a low CD4 count and neutrophilia are. Elevation of the MO-Y shows some promise as a potential biomarker of antitumour immunity; further study in this regard would be of interest.

ß-Cyclodextrin Polymer-Based Fluorescence Enhancement Strategy via Host-Guest Interaction for Sensitive Assay of SARS-CoV-2.

Nucleocapsid protein (N protein) is an appropriate target for early determination of viral antigen-based severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We have found that ß-cyclodextrin polymer (ß-CDP) has shown a significant fluorescence enhancement effect for fluorophore pyrene via host-guest interaction. Herein, we developed a sensitive and selective N protein-sensing method that combined the host-guest interaction fluorescence enhancement strategy with high recognition of aptamer. The DNA aptamer of N protein modified with pyrene at its 3' terminal was designed as the sensing probe. The added exonuclease I (Exo I) could digest the probe, and the obtained free pyrene as a guest could easily enter into the hydrophobic cavity of host ß-CDP, thus inducing outstanding luminescent enhancement. While in the presence of N protein, the probe could combine with it to form a complex owing to the high affinity between the aptamer and the target, which prevented the digestion of Exo I. The steric hindrance of the complex prevented pyrene from entering the cavity of ß-CDP, resulting in a tiny fluorescence change. N protein has been selectively analyzed with a low detection limit (11.27 nM) through the detection of the fluorescence intensity. Moreover, the sensing of spiked N protein from human serum and throat swabs samples of three volunteers has been achieved. These results indicated that our proposed method has broad application prospects for early diagnosis of coronavirus disease 2019.

A computational two-photon fluorescence approach for revealing label-free the 3D image of viruses and bacteria.

Current solutions for bacteria and viruses identification are based on time-consuming technics with complex preparation procedures. In the present work, we revealed label-free the presence of free viral particles and bacteria with a computational two-photon fluorescence (C-TPF) strategy. Six bacteria were tested: Escherichia coli, Staphylococcus epidermidis, Proteus vulgaris, Pseudomonas fluorescens, Bacillus subtilis, and Clostridium perfringens. The two families of viral particles were the herpes virus with the cytomegalovirus (CMV, 300 nm of diameter) and the coronavirus with the SARS-CoV-2 (100 nm of diameter). The instrumental and computational pipeline FAMOUS optimized the produced 3D images. The origin of the fluorescence emission was discussed for bacteria regarding to their two-photon excitation spectra and attributed to the metabolic indicators (FAD and NADH). The optical and computational strategy constitute a new approach for imaging label-free viral particles and bacteria and paves the way to a new understanding of viral or bacterial ways of infection.

Development of Fluorescence-Tagged SARS-CoV-2 Virus-like Particles by a Tri-Cistronic Vector Expression System for Investigating the Cellular Entry of SARS-CoV-2.

Severe acute respiratory syndrome-related coronavirus-2 (SARS-CoV-2) has caused the pandemic that began late December 2019. The co-expression of SARS-CoV-2 structural proteins in cells could assemble into several types of virus-like particles (VLPs) without a viral RNA genome. VLPs containing S proteins with the structural and functional properties of authentic virions are safe materials to exploit for virus-cell entry and vaccine development. In this study, to generate SARS-CoV-2 VLPs (SCoV2-SEM VLPs) composed of three structural proteins including spike (S), envelop (E) protein and membrane (M) protein, a tri-cistronic vector expression system was established in a cell line co-expressing SARS-CoV-2 S, E and M proteins. The SCoV2-SEM VLPs were harvested from the cultured medium, and three structure proteins were confirmed by Western blot assay. A negative-stain TEM assay demonstrated the size of the SCoV2-SEM VLPs with a diameter of about 90 nm. To further characterize the infectious properties of SCoV2-SEM VLPs, the VLPs (atto647N-SCoV2-SEM VLPs) were fluorescence-labeled by conjugation with atto-647N and visualized under confocal microscopy at a single-particle resolution. The results of the infection assay revealed that atto647N-SCoV2-SEM VLPs attached to the surface of the HEK293T cells at the pre-binding phase in a ACE2-dependent manner. At the post-infection phase, atto647N-SCoV2-SEM VLPs either fused with the cellular membrane or internalized into the cytoplasm with mCherry-rab5-positive early endosomes. Moreover, fusion with the cellular membrane and the internalization with early endosomes could be inhibited by the treatment of camostat (a pharmacological inhibitor of TMPRSS2) and chlorpromazine (an endocytosis inhibitor), respectively. These results elucidated that SCoV2-SEM VLPs behave similarly to the authentic live SARS-CoV-2 virus, suggesting that the development of SCoV2-SEM VLPs provide a realistic and safe experimental model for studying the infectious mechanism of SARS-CoV-2.

Organic Light-Emitting Diode Based Fluorescence-Linked Immunosorbent Assay for SARS-CoV-2 Antibody Detection.

Immunodiagnostics have been widely used in the detection of disease biomarkers. The conventional immunological tests in central laboratories require expensive equipment and, for non-specialists, the tests are technically demanding and time-consuming, which has prevented their use by the public. Thus, point-of-care tests (POCT), such as lateral flow immunoassays, are being, or have been, developed as more convenient and low-cost methods for immunodiagnostics. However, the sensitivity of such tests is often a concern. Here, a fluorescence-linked immunosorbent assay (FLISA) using organic light-emitting diodes (OLEDs) as excitation light sources was investigated as a way forward for the development of compact and sensitive POCTs. Phycoerythrin (PE) was selected as the fluorescent dye, and OLEDs were designed with different emission spectra. The leakage light of different OLEDs for exciting PE was then investigated to reduce the background noise and improve the sensitivity of the system. Finally, as proof-of-principle that OLED-based technology can be successfully further developed for POCT, antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in human serum was detected by OLED-FLISA.

Fluorescence-Based Measurements of Membrane-Bound Angiotensin Converting Enzyme 2 Activity Using Xenopus Laevis Oocytes.

Functional investigations of enzymes involving cellular expression systems are important for pharmacological studies. The precise control of expression is challenging in transiently transfected mammalian cell lines. Here, we explored the ability of Xenopus laevis oocytes to express a membrane-bound enzyme for functional characterization using standard 96-well plates and a fluorescence-based plate reader assay. We microinjected oocytes with cRNA encoding the angiotensin converting enzyme 2 (ACE2) and measured the enzymatic activity in single oocytes using a commercial fluorescence-based assay. The injected oocytes showed up to a 50-fold increase in fluorescence compared to uninjected oocytes. This fluorescence intensity was dose-dependent on the amount of ACE2 cRNA. These results suggest that Xenopus oocytes can be used for the functional evaluation of membrane-bound enzymes, decreasing the experimental workload.

Optimized production and fluorescent labeling of SARS-CoV-2 virus-like particles.

SARS-CoV-2 is an RNA enveloped virus responsible for the COVID-19 pandemic that conducted in 6 million deaths worldwide so far. SARS-CoV-2 particles are mainly composed of the 4 main structural proteins M, N, E and S to form 100 nm diameter viral particles. Based on productive assays, we propose an optimal transfected plasmid ratio mimicking the viral RNA ratio in infected cells. This allows SARS-CoV-2 Virus-Like Particle (VLPs) formation composed of the viral structural proteins M, N, E and mature S. Furthermore, fluorescent or photoconvertible VLPs were generated by adding a fluorescent protein tag on N or M mixing with unlabeled viral proteins and characterized by western blots, atomic force microscopy coupled to fluorescence and immuno-spotting. Thanks to live fluorescence and super-resolution microscopies, we quantified VLPs size and concentration. SARS-CoV-2 VLPs present a diameter of 110 and 140 nm respectively for MNE-VLPs and MNES-VLPs with a concentration of 10e12 VLP/ml. In this condition, we were able to establish the incorporation of the Spike in the fluorescent VLPs. Finally, the Spike functionality was assessed by monitoring fluorescent MNES-VLPs docking and internalization in human pulmonary cells expressing or not the receptor hACE2. Results show a preferential maturation of S on N(GFP) labeled VLPs and an hACE2-dependent VLP internalization and a potential fusion in host cells. This work provides new insights on the use of non-fluorescent and fluorescent VLPs to study and visualize the SARS-CoV-2 viral life cycle in a safe environment (BSL-2 instead of BSL-3). Moreover, optimized SARS-CoV-2 VLP production can be further adapted to vaccine design strategies.

A smartphone-based platform for ratiometric visualization of SARS-CoV-2 via an oligonucleotide probe.

COVID-19 necessitates the development of reliable and convenient diagnostic tools. In this work, a facile 3D-printed smartphone platform was constructed that achieved reliable visual detection of SARS-CoV-2 by eliminating the effect of ambient light and fixing the camera position relative to the sample. The oligonucleotide probe is modified with orange-red-emitting TAMRA working as an internal standard and green-emitting FAM serving as a sensitive sensing agent. Under 365-nm UV excitation, the emission wavelengths of TAMRA and FAM are 580 nm and 518 nm, respectively. When the probes interact with the targets, the green fluorescence gradually restores while the orange-red fluorescence remains stable. Thus, a striking color transition from orange-red to green could be observed by the naked eye. The detection limit of SARS-CoV-2 nucleic acid is 0.23 nM, and the entire process of color change could be completed in 25 min. Furthermore, the RGB value analysis of the sample solution was conducted using a smartphone for reliable and reproducible discrimination of SARS-CoV-2. The proposed smartphone platform might establish a general method for visual detection of SARS-CoV-2 nucleic acid as well as other virus-related diseases.

FluoRNT: A robust, efficient assay for the detection of neutralising antibodies against yellow fever virus 17D.

There is an urgent need for better diagnostic and analytical methods for vaccine research and infection control in virology. This has been highlighted by recently emerging viral epidemics and pandemics (Zika, SARS-CoV-2), and recurring viral outbreaks like the yellow fever outbreaks in Angola and the Democratic Republic of Congo (2016) and in Brazil (2016-2018). Current assays to determine neutralising activity against viral infections in sera are costly in time and equipment and suffer from high variability. Therefore, both basic infection research and diagnostic population screenings would benefit from improved methods to determine virus-neutralising activity in patient samples. Here we describe a robust, objective, and scalable Fluorescence Reduction Neutralisation Test (FluoRNT) for yellow fever virus, relying on flow cytometric detection of cells infected with a fluorescent Venus reporter containing variant of the yellow fever vaccine strain 17D (YF-17D-Venus). It accurately measures neutralising antibody titres in human serum samples within as little as 24 h. Samples from 32 vaccinees immunised with YF-17D were tested for neutralising activity by both a conventional focus reduction neutralisation test (FRNT) and FluoRNT. Both types of tests proved to be equally reliable for the detection of neutralising activity, however, FluoRNT is significantly more precise and reproducible with a greater dynamic range than conventional FRNT. The FluoRNT assay protocol is substantially faster, easier to control, and cheaper in per-assay costs. FluoRNT additionally reduces handling time minimising exposure of personnel to patient samples. FluoRNT thus brings a range of desirable features that can accelerate and standardise the measurement of neutralising anti-yellow fever virus antibodies. It could be used in applications ranging from vaccine testing to large cohort studies in systems virology and vaccinology. We also anticipate the potential to translate the methodology and analysis of FluoRNT to other flaviviruses such as West Nile, Dengue and Zika or to RNA viruses more generally.

Fluorescence signatures of SARS-CoV-2 spike S1 proteins and a human ACE-2: excitation-emission maps and fluorescence lifetimes.

SIGNIFICANCE: Fast and reliable detection of infectious SARS-CoV-2 virus loads is an important issue. Fluorescence spectroscopy is a sensitive tool to do so in clean environments. This presumes a comprehensive knowledge of fluorescence data. AIM: We aim at providing fully featured information on wavelength and time-dependent data of the fluorescence of the SARS-CoV-2 spike protein S1 subunit, its receptor-binding domain (RBD), and the human angiotensin-converting enzyme 2, especially with respect to possible optical detection schemes. APPROACH: Spectrally resolved excitation-emission maps of the involved proteins and measurements of fluorescence lifetimes were recorded for excitations from 220 to 295 nm. The fluorescence decay times were extracted by using a biexponential kinetic approach. The binding process in the SARS-CoV-2 RBD was likewise examined for spectroscopic changes. RESULTS: Distinct spectral features for each protein are pointed out in relevant spectra extracted from the excitation-emission maps. We also identify minor spectroscopic changes under the binding process. The decay times in the biexponential model are found to be ( 2.0 ± 0.1 ) ns and ( 8.6 ± 1.4 ) ns. CONCLUSIONS: Specific material data serve as an important background information for the design of optical detection and testing methods for SARS-CoV-2 loaded media.

Nail and hair findings developing in patients treated for COVID-19 infection fluorescence of keratinized tissues on Wood's lamp in COVID-19 disease.

BACKGROUND: The new severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) is the causative agent of coronavirus 2019 (COVID-2019) disease. A wide variety of symptoms of the disease has been frequently reported in the literature in recent years. However, information on the findings in keratinized tissues is still limited. Data on changes in keratinized tissues such as nails, teeth and hair, and oral mucousa due to drugs used in the treatment of this disease are also extremely insufficient. AIM: With this study, it was aimed to evaluate the changes in the keratinized tissues of our patients with COVID-19, who are frequently encountered in the Ear Nose and Throat outpatient clinic. MATERIALS AND METHOD: The study was carried out on patients who applied to Baskent University Ear Nose and Throat clinic. There were 3 groups. The first group consisted of patients diagnosed with COVID-19 and received relevant medical treatments, the second group included individuals who have never experienced COVID-19 infection but have been vaccinated against COVID-19, and the third group is the control group with normal healthy individuals who have never been diagnosed with COVID-19 infection and have not been vaccinated so far. With the Wood's lamp, fluorescent changes in nails, hair, tooth, and the oral mucousa were recorded. RESULTS: A total of 124(75 females, 49 males) patients were included in the study. Positive Wood's finding was significantly higher in COVID-19 group(Group 1) who received Favipravir when compared with individuals who did not receive Favipravir (p < 0.001). Wood's positivity was not detected in any of the individuals who did not use favipravir. The rate of determining Wood's positivity in favipravir users decreases after 58 days. DISCUSSION: Accordingly, Favipravir accumulation in the kretainized tissues manifest positive Wood's sign in our study. CONCLUSION: The adverse effects of the accumulation of the drugs-mainly Favipravir-used in the treatment of COVID-19 disease, have not yet been clearly demonstrated so far. Revealing the findings in these tissues with this study will pave the way for investigating changes or drug sequestrations in other organs in the long term.

Target Deoxyribonucleic Acid-Recycled Lighting-Up Amplifiable Ratiometric Fluorescence Biosensing of Bicolor Silver Nanoclusters Hosted in a Switchable Deoxyribonucleic Acid Construct.

Ratiometric assays of label-free dual-signaling reporters with enzyme-free amplification are intriguing yet challenging. Herein, yellow- and red-silver nanocluster (yH-AgNC and rH-AgNC) acting as bicolor ratiometric emitters are guided to site-specifically cluster in two template signaling hairpins (yH and rH), respectively, and originally, both of them are almost non-fluorescent. The predesigned complement tethered in yH is recognizable to a DNA trigger (TOC) related to SARS-CoV-2. With the help of an enhancer strand (G15E) tethering G-rich bases (G15) and a linker strand (LS), a switchable DNA construct is assembled via their complementary hybridizing with yH and rH, in which the harbored yH-AgNC close to G15 is lighted-up. Upon introducing TOC, its affinity ligating with yH is further implemented to unfold rH and induce the DNA construct switching into closed conformation, causing TOC-repeatable recycling amplification through competitive strand displacement. Consequently, the harbored rH-AgNC is also placed adjacent to G15 for turning on its red fluorescence, while the yH-AgNC is retainable. As demonstrated, the intensity ratio dependent on varying TOC is reliable with high sensitivity down to 0.27 pM. By lighting-up dual-cluster emitters using one G15 enhancer, it would be promising to exploit a simpler ratiometric biosensing format for bioassays or clinical theranostics.

A Lab-in-a-Fiber optofluidic device using droplet microfluidics and laser-induced fluorescence for virus detection.

Microfluidics has emerged rapidly over the past 20 years and has been investigated for a variety of applications from life sciences to environmental monitoring. Although continuous-flow microfluidics is ubiquitous, segmented-flow or droplet microfluidics offers several attractive features. Droplets can be independently manipulated and analyzed with very high throughput. Typically, microfluidics is carried out within planar networks of microchannels, namely, microfluidic chips. We propose that fibers offer an interesting alternative format with key advantages for enhanced optical coupling. Herein, we demonstrate the generation of monodisperse droplets within a uniaxial optofluidic Lab-in-a-Fiber scheme. We combine droplet microfluidics with laser-induced fluorescence (LIF) detection achieved through the development of an optical side-coupling fiber, which we term a periscope fiber. This arrangement provides stable and compact alignment. Laser-induced fluorescence offers high sensitivity and low detection limits with a rapid response time making it an attractive detection method for in situ real-time measurements. We use the well-established fluorophore, fluorescein, to characterize the Lab-in-a-Fiber device and determine the generation of [Formula: see text] 0.9 nL droplets. We present characterization data of a range of fluorescein concentrations, establishing a limit of detection (LOD) of 10 nM fluorescein. Finally, we show that the device operates within a realistic and relevant fluorescence regime by detecting reverse-transcription loop-mediated isothermal amplification (RT-LAMP) products in the context of COVID-19 diagnostics. The device represents a step towards the development of a point-of-care droplet digital RT-LAMP platform.

Reuse of Personal Protective Equipment: Results of a Human Factors Study Using Fluorescence to Identify Self-Contamination During Donning and Doffing.

BACKGROUND: At least 115,000 health and care workers (HCWs) are estimated to have lost their lives to COVID-19, according to the the chief of the World Health Organization (WHO). Personal protective equipment (PPE) is the first line of defense for HCWs against infectious diseases. At the height of the pandemic, PPE supplies became scarce, necessitating reuse, which increased the occupational COVID-19 risks to HCWs. Currently, there are few robust studies addressing PPE reuse and practice variability, leaving HCWs vulnerable to accidental contamination and harm. OBJECTIVE: The objective of this study was to assess potential HCW contamination during PPE donning, doffing, and reuse. METHODS: The study included 28 active acute care physicians, nurses, and nurse practitioners that evaluated 5 simulated patients with COVID-like symptoms while donning and doffing PPE between each patient encounter. An N95 mask was contaminated with a transparent fluorescent gel applied to the outside of the N95 mask to simulate contamination that might occur during reuse. Participants were evaluated after PPE doffing for each encounter using a black light to assess for face and body contamination. RESULTS: All participants had multiple sites of contamination, predominantly on their head and neck. None of the participants were able to don and doff PPE without contaminating themselves during five consecutive simulation cycles. CONCLUSIONS: The current Centers for Disease Control and Prevention PPE guidelines for donning and doffing fall short in protecting HCWs. They do not adequately protect HCWs from contamination. There is an urgent need for PPE and workflow redesign.

The effectiveness of the Safety in Interventional Radiology (SIR) Shield in reducing droplet transmission and its effect on image quality and radiation dose.

OBJECTIVE: To evaluate the efficacy of a barrier shield in reducing droplet transmission and its effect on image quality and radiation dose in an interventional suite. METHODS: A human cough droplet visualisation model in a supine position was developed to assess efficacy of barrier shield in reducing environmental contamination. Its effect on image quality (resolution and contrast) was evaluated via image quality test phantom. Changes in the radiation dose to patient post-shield utilisation was measured. RESULTS: Use of the shield prevented escape of visible fluorescent cough droplets from the containment area. No subjective change in line-pair resolution was observed. No significant difference in contrast-to-noise ratio was measured. Radiation dosage to patient was increased; this is predominantly attributed to the increased air gap and not the physical properties of the shield. CONCLUSION: Use of the barrier shield provided an effective added layer of personal protection in the interventional radiology theatre for aerosol generating procedures. ADVANCES IN KNOWLEDGE: This is the first time a human supine cough droplet visualisation has been developed. While multiple types of barrier shields have been described, this is the first systematic practical evaluation of a barrier shield designed for use in the interventional radiology theatre.

NEUT-SFL in Patients with COVID-ARDS: A Novel Biomarker for Thrombotic Events?

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an enveloped RNA virus first identified in December 2019 in Wuhan, China, and responsible for coronavirus disease 2019 (COVID-19). The ongoing COVID-19 pandemic is impacting healthcare worldwide. Patients who develop coagulopathy have worse outcomes. The pathophysiology of COVID-19 suggests a strong interplay between hemostasis and immune cells, especially neutrophils. Our purpose was to assess neutrophil fluorescence as a potential biomarker of deep vein thrombosis (DVT) in patients with COVID-acute respiratory distress syndrome (COVID-ARDS). Sixty-one patients with COVID-ARDS admitted to the four intensive care units (ICUs) of a French general hospital were included in this prospective study. Neutrophil activation was assessed by measuring neutrophil fluorescence (NEUT-Side Fluorescence Light, NEUT-SFL) with a specific fluorescent dye staining analyzed by a routine automated flow cytometer Sysmex XN-3000™ (Sysmex, Kobe, Japan). DVT was diagnosed by complete duplex ultrasound (CDU). We found that NEUT-SFL was elevated on admission in patients with COVID-ARDS (49.76 AU, reference value 46.40 AU, p < 0.001), but did not differ between patients with DVT (49.99 AU) and those without (49.52 AU, p = 0.555). NEUT-SFL is elevated in patients with COVID-ARDS, reflecting neutrophil activation, but cannot be used as a marker of thrombosis. Because neutrophils are at interface between immune response and hemostasis through release of neutrophil extracellular traps, monitoring their activation could be an interesting approach to improve our management of coagulopathy during COVID-ARDS. Further research is needed to better understand the pathophysiology of COVID-19 and identify high-performance biomarkers.