Efficient capture of recombinant SARS-CoV-2 receptor-binding domain (RBD) with citrate-coated magnetic iron oxide nanoparticles.

Several vaccines against COVID-19 use a recombinant SARS-CoV-2 receptor-binding domain (RBD) as antigen, making the purification of this protein a key step in their production. In this work, citrate-coated magnetic iron oxide nanoparticles were evaluated as nano adsorbents in the first step (capture) of the purification of recombinant RBD. The nanoparticles were isolated through coprecipitation and subsequently coated with sodium citrate. The citrate-coated nanoparticles exhibited a diameter of 10 ± 2 nm, a hydrodynamic diameter of 160 ± 3 nm, and contained 1.9 wt% of citrate. The presence of citrate on the nanoparticles' surface was confirmed through FT-IR spectra and thermogravimetric analysis. The crystallite size (10.1 nm) and the lattice parameter (8.3646 Å) were determined by X-ray diffraction. In parallel, RBD-containing supernatant extracted from cell culture was exchanged through ultrafiltration and diafiltration into the adsorption buffer. The magnetic capture was then optimized using different concentrations of nanoparticles in the purified supernatant, and we found 40 mg mL-1 to be optimal. The ideal amount of nanoparticles was assessed by varying the RBD concentration in the supernatant (between 0.113 mg mL-1 and 0.98 mg mL-1), which resulted in good capture yields (between 83 ± 5% and 94 ± 4%). The improvement of RBD purity after desorption was demonstrated by SDS-PAGE and RP-HPLC. Furthermore, the magnetic capture was scaled up 100 times, and the desorption was subjected to chromatographic purifications. The obtained products recognized anti-RBD antibodies and bound the ACE2 receptor, proving their functionality after the developed procedure.

Modulation of ATP Production Influences Inorganic Polyphosphate Levels in Non-Athletes' Platelets at the Resting State.

Platelets produce inorganic polyphosphate (polyP) upon activation to stimulate blood coagulation. Some researchers have linked polyP metabolism to ATP production, although the metabolic linkage is yet to be elucidated. We found evidence for this possibility in our previous study on professional athletes (versus non-athletes), and proposed that the regulatory mechanism might be different for these two groups. To explore this aspect further, we investigated the effects of modulated ATP production on polyP levels. Blood samples were obtained from Japanese healthy, non-athletes in the presence of acid-citrate-dextrose. The platelets in the plasma were treated with oligomycin, rotenone, and GlutaMAX to modulate ATP production. PolyP level was quantified fluorometrically and visualized using 4',6-diamidino-2-phenylindole. Correlations between polyP and ATP or NADH were then calculated. Contrary to the hypothesis, inhibitors of ATP production increased polyP levels, whereas amino acid supplementation produced the opposite effect. In general, however, polyP levels were positively correlated with ATP levels and negatively correlated with NADH levels. Since platelets are metabolically active, they exhibit high levels of ATP turnover rate. Therefore, these findings suggest that ATP may be involved in polyP production in the resting platelets of non-athletes.

Regional citrate and systemic heparin are adequate to maintain filter half-life for COVID-19 patients on continuous renal replacement therapy.

INTRODUCTION: The aim of our study is to compare clotting of CRRT filters in patients with COVID-19-associated AKI versus septic shock-associated AKI. METHODS: Retrospective study of adult ICU patients with COVID-19 compared to those with septic shock admitted to a tertiary hospital April-October 2020. Independent t test and chi-square test used to determine statistical significance of CRRT filter clotting between the two groups. Time-to-event data analyzed with Kaplan-Meier curves. Analyses performed on Microsoft Excel and MedCalc. RESULTS: Twenty-seven ICU patients with AKI requiring CRRT were included, 13 with COVID-19 and 14 non-COVID-19 patients with septic shock. The mean half-life of CRRT hemofilter was similar in COVID-19 patients compared to non-COVID-19 patients (27.4 vs. 27.5 h, p = 0.79). The number of CRRT hemofilter changes per day was similar in both groups (0.6 filter changes per day, p = 0.84). However, significantly more patients with COVID-19 were on systemic heparin (69% vs. 13%, p = 0.02). CONCLUSION: We found that COVID-19 patients with AKI requiring CRRT had similar CRRT hemofilter half-life compared with sepsis-associated AKI patients with use of regional citrate and systemic heparin. Further studies are needed to find which methods of anticoagulation are optimal in patients with COVID-19 infection with AKI requiring CRRT.

Prognostic value of circulating calprotectin levels on the clinical course of COVID-19 differs between serum, heparin, EDTA and citrate sample types.

INTRODUCTION: During the recent SARS-CoV-2 pandemic, circulating calprotectin (cCLP) gained interest as biomarker to predict the severity of COVID-19. We aimed to investigate the prognostic value of cCLP measured in serum, heparin, EDTA and citrate plasma. MATERIALS AND METHODS: COVID-19 patients were prospectively included, in parallel with two SARS-CoV-2 negative control populations. The prognostic value of cCLP was compared with IL-6, CRP, LDH, procalcitonin, and the 4C-mortality score by AUROC analysis. RESULTS: For the 136 COVID-19 patients, cCLP levels were higher compared to the respective control populations, with significantly higher cCLP levels in serum and heparin than in EDTA or citrate. Higher cCLP levels were obtained for COVID-19 patients with i) severe/critical illness (n = 70), ii) ICU admission (n = 66) and iii) need for mechanical ventilation/ECMO (n = 25), but iv) not in patients who deceased within 30 days (n = 41). The highest discriminatory power (AUC [95% CI]) for each defined outcome was i) CRP (0.835 [0.755-0.914]); ii) EDTA cCLP (0.780 [0.688-0.873]); iii) EDTA cCLP (0.842 [0.758-0.925]) and iv) the 4C-mortality score (0.713 [0.608-0.818]). CONCLUSION: Measuring cCLP in COVID-19 patients helps the clinician to predict the clinical course of COVID-19. The discriminatory power of EDTA and citrate plasma cCLP levels often outperforms heparin plasma cCLP levels.

Efficacy and complications of regional citrate anticoagulation during continuous renal replacement therapy in critically ill patients with COVID-19.

BACKGROUND: We compared filter survival and citrate-induced complications during continuous renal replacement therapy (CRRT) with regional citrate anticoagulation (RCA) in COVID-19 and Non-COVID-19 patients. METHODS: In this retrospective study we included all consecutive adult patients (n = 97) treated with RCA-CRRT. Efficacy and complications of RCA-CRRT were compared between COVID-19 and Non-COVID-19 patients. RESULTS: Mean filter run-time was significantly higher in COVID-19 patients compared to Non-COVID-19 patients (68.4 (95%CI 67.0-69.9) vs. 65.2 (95%CI 63.2-67.2) hours, respectively; log-rank 0.014). COVID-19 patients showed significantly higher activated partial thromboplastin time (aPTT) throughout the CRRT due to intensified systemic anticoagulation compared to Non-COVID-19 patients (54 (IQR 45-61) vs. 47 (IQR 41-58) seconds, respectively; p < 0.001). A significantly higher incidence of metabolic alkalosis, hypercalcemia and hypernatremia, consistent with reduced filter patency and citrate overload, was observed in COVID-19 patients compared to Non-COVID-19 patients (19.1% vs. 12.7%, respectively; p = 0.04). These metabolic disarrangements were resistant to per-protocol adjustments and disappeared after replacement of the CRRT-filter. CONCLUSIONS: RCA-CRRT in COVID-19 patients with intensified systemic anticoagulation provides an adequate filter lifespan. However, close monitoring of the acid-base balance appears warranted, as these patients tend to develop reduced filter patency leading to a higher incidence of citrate overload and metabolic disturbances. TRIAL REGISTRATION (LOCAL AUTHORITY): EA1/285/20 (Ethikkommission der Charité - Universitätsmedizin Berlin); date of registration 08.10.2020.

Targeting Citrate Carrier (CIC) in Inflammatory Macrophages as a Novel Metabolic Approach in COVID-19 Patients: A Perspective.

Coronavirus disease-19 (COVID-19) can be a fatal disease and is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV2). SARS-CoV2 is an enveloped virus that belongs to the Beta coronavirus subfamily. After entering into the target cells, this virus replicates rapidly and leads to cellular damage and uncontrolled pulmonary inflammation. Huge amounts of inflammatory cytokines and chemokines are produced by infected lung cells and are associated with monocyte recruitment and accumulation of inflammatory macrophages at the site of infection. Mitochondrial citrate carrier (CIC) expression increases in these macrophages, which results in elevated levels of cytosolic citrate and the production of inflammatory mediators. In this perspective article, we discuss the role of mitochondrial CIC in the metabolism of inflammatory macrophages and we propose that inhibition of this carrier might be a novel therapeutic approach for COVID-19 patients.

Therapeutic plasma exchange (TPE) as a plausible rescue therapy in severe vaccine-induced immune thrombotic thrombocytopenia.

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is associated with high titers of immunoglobulin G class antibodies directed against the cationic platelet chemokine platelet factor 4 (PF4). These antibodies activate platelets via FcγIIa receptors. VITT closely resembles heparin-induced thrombocytopenia. Inflammation and tissue trauma substantially increase the risk for forming pathogenic PF4 antibodies. We therefore propose the use of therapeutic plasma exchange as rescue therapy in VITT to deplete antibodies plus factors promoting inflammation such as excess cytokines in the circulation as well as extracellular vesicles derived from activated platelets.

Pediatric bowel preparation: Sodium picosulfate, magnesium oxide, citric acid vs polyethylene glycol, a randomized trial.

BACKGROUND: Bowel preparation in children can be challenging. AIM: To describe the efficacy, safety, and tolerability of sodium picosulfate, magnesium oxide, and citric acid (SPMC) bowel preparation in children. METHODS: Phase 3, randomized, assessor-blinded, multicenter study of low-volume, divided dose SPMC enrolled children 9-16 years undergoing elective colonoscopy. Participants 9-12 years were randomized 1:1:1 to SPMC ½ dose × 2, SPMC 1 dose × 2, or polyethylene glycol (PEG). Participants 13-16 years were randomized 1:1 to SPMC 1 dose × 2 or PEG. PEG-based bowel preparations were administered per local protocol. Primary efficacy endpoint for quality of bowel preparation was responders (rating of 'excellent' or 'good') by modified Aronchick Scale. Secondary efficacy endpoint was participant's tolerability and satisfaction from a 7-item questionnaire. Safety assessments included adverse events (AEs) and laboratory evaluations. RESULTS: 78 participants were randomized, 48 were 9-12 years, 30 were 13-16 years. For the primary efficacy endpoint in 9-12 years, 50.0%, 87.5%, and 81.3% were responders for SPMC ½ dose × 2, SPMC 1 dose × 2, and PEG groups, respectively. Responder rates for 13-16 years were 81.3% for SPMC 1 dose × 2 and 85.7% for PEG. Overall, 43.8% of participants receiving SPMC 1 dose × 2 reported it was 'very easy' or 'easy' to drink, compared with 20.0% receiving PEG. Treatment-emergent AEs were reported by 45.5% of participants receiving SPMC 1 dose × 2 and 63.0% receiving PEG. CONCLUSION: SPMC was an efficacious and safe for bowel preparation in children 9-16 years, with comparable efficacy to PEG. Tolerability for SPMC was higher compared to PEG.

Preparation of cellulose-based wipes treated with antimicrobial and antiviral silver nanoparticles as novel effective high-performance coronavirus fighter.

Coronaviruses (CoV) are a large family of viruses that cause illness ranging from the common cold to more severe diseases such as Middle East Respiratory Syndrome (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS-CoV). We succeeded in preparing disinfectant cellulose-based wipes treated with antimicrobial and antiviral silver nanoparticles to be used for prevention of contamination and transmission of several pathogenic viruses and microbes to human in critical areas such as hospitals and healthcare centers especially coronavirus. In this work, the antimicrobial and antiviral activities of silver nanoparticles (AgNPs) prepared with four different techniques were investigated for the utilization as a disinfectant for cellulose-based wipes. These four methods are namely; 1) trisodium citrate with cotton yarn as a reducing agent, 2) preparing AgNP's using aqueous solution of PVA in the presence of glucose, 3) trisodium citrate with cotton fabric as a reducing agent, and 4) photochemical reaction of polyacrylic acid and silver nitrate solution. Polyester/viscose blended spunlace nonwoven fabrics as cellulose based fabrics were treated with the prepared silver nanoparticles to be used as surfaces disinfection wipes. The properties of the nonwoven fabrics were examined including thickness, tensile strength in dry and wet conditions in both machine direction (MD) and cross-machine direction (CMD), bursting strength, air permeability, water permeability and surface wettability. Characterization of the AgNPs was carried out in terms of UV-VIS spectroscopy, TEM, SEM, and Zeta potential analysis. The assessment of AgNPs active solutions for antimicrobial and antiviral activities was evaluated. The results obtained from the analyses of the AgNPs samples prepared with different techniques showed good uniformity and stability of the particles, as well uniform coating of the AgNPs on the fibers. Additionally, there is a significant effect of the AgNPs preparation method on their disinfectant performance that proved its effectiveness against coronavirus (MERS-CoV), S. aureus and B. subtilis as Gram-positive bacteria, E. coli and P. mirabilis as Gram-negative bacteria, A. niger and C. albicans fungi.

Acute Kidney Injury and Special Considerations during Renal Replacement Therapy in Children with Coronavirus Disease-19: Perspective from the Critical Care Nephrology Section of the European Society of Paediatric and Neonatal Intensive Care.

Children seem to be less severely affected by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) as compared to adults. Little is known about the prevalence and pathogenesis of acute kidney injury (AKI) in children affected by SARS-CoV-2. Dehydration seems to be the most common trigger factor, and meticulous attention to fluid status is imperative. The principles of initiation, prescription, and complications related to renal replacement therapy are the same for coronavirus disease (COVID) patients as for non-COVID patients. Continuous renal replacement therapy (CRRT) remains the most common modality of treatment. When to initiate and what modality to use are dependent on the available resources. Though children are less often and less severely affected, diversion of all hospital resources to manage the adult surge might lead to limited CRRT resources. We describe how these shortages might be mitigated. Where machines are limited, one CRRT machine can be used for multiple patients, providing a limited number of hours of CRRT per day. In this case, increased exchange rates can be used to compensate for the decreased duration of CRRT. If consumables are limited, lower doses of CRRT (15-20 mL/kg/h) for 24 h may be feasible. Hypercoagulability leading to frequent filter clotting is an important issue in these children. Increased doses of unfractionated heparin, combination of heparin and regional citrate anticoagulation, or combination of prostacyclin and heparin might be used. If infusion pumps to deliver anticoagulants are limited, the administration of low-molecular-weight heparin might be considered. Alternatively in children, acute peritoneal dialysis can successfully control both fluid and metabolic disturbances. Intermittent hemodialysis can also be used in patients who are hemodynamically stable. The keys to successfully managing pediatric AKI in a pandemic are flexible use of resources, good understanding of dialysis techniques, and teamwork.