Copolymerized Polymers Based on Cyclodextrins and Cationic Groups Enhance Therapeutic Effect of Rebamipide in the N-Acetylcysteine-Treated Dry Eye Model.

Purpose: We aimed to prepare a ß-cyclodextrin (ß-CD) polymer using radical polymerization with co-monomers, 6-deoxy-6-(2-methacryloyloxyethylsuccinamide)-ß-cyclodextrin (CD-MSAm) and N,N,N-trimethyl-N-(2-hydroxy-3-metacryloyloxopropyl)-ammonium chloride (QA) to design cyclodextrins suitable for use in ophthalmology. In addition, we evaluated their solubility and inclusion properties with rebamipide (REB), a poorly soluble drug, and investigated the usefulness of the ß-CD polymer and REB (REB@CDQA) combination in treating dry eye. Methods: The ß-CD polymer (CD-MSAm-co-QA, CDQA) based on CD-MSAm/QA was prepared via radical polymerization, and the usefulness of REB@CDQA in treating dry eye was evaluated using a rabbit treated with N-acetylcysteine (dry eye model). Results: The solubility of the CDQA powder was higher than that of the ß-CD powder, and 80 nm colloids were observed in the CDQA solution. No corneal toxicity was observed in human corneal epithelial cells or rat corneas treated with 0.2% CDQA solution. The levels of REB dissolved in the CDQA solution were higher than those of the ß-CD solution. Moreover, the application of the CDQA solution enhanced REB retention in the cornea and attenuated the transcorneal penetration of REB. In addition, instillation of REB@CDQA enhanced the volume of the lacrimal fluid and normalized the reduced mucin levels in the dry eye model. The extent of tear film breakup was attenuated by REB@CDQA instillation. Conclusion: The CDQA solution enhanced the solubility of REB, and the combination of CDQA and REB enhanced the drug content in the corneal tissue. Moreover, the therapeutic effect on dry eye was higher than that of REB suspensions without CDQA.

Emergence of transmissible SARS-CoV-2 variants with decreased sensitivity to antivirals in immunocompromised patients with persistent infections.

We investigated the impact of antiviral treatment on the emergence of SARS-CoV-2 resistance during persistent infections in immunocompromised patients (n = 15). All patients received remdesivir and some also received nirmatrelvir-ritonavir (n = 3) or therapeutic monoclonal antibodies (n = 4). Sequence analysis showed that nine patients carried viruses with mutations in the nsp12 (RNA dependent RNA polymerase), while four had viruses with nsp5 (3C protease) mutations. Infectious SARS-CoV-2 with a double mutation in nsp5 (T169I) and nsp12 (V792I) was recovered from respiratory secretions 77 days after initial COVID-19 diagnosis from a patient sequentially treated with nirmatrelvir-ritonavir and remdesivir. In vitro characterization confirmed its decreased sensitivity to remdesivir and nirmatrelvir, which was overcome by combined antiviral treatment. Studies in golden Syrian hamsters demonstrated efficient transmission to contact animals. This study documents the isolation of SARS-CoV-2 carrying resistance mutations to both nirmatrelvir and remdesivir from a patient and demonstrates its transmissibility in vivo.

An Ala/Glu difference in E1 of Cx26 and Cx30 contributes to their differential anionic permeabilities.

Two closely related connexins, Cx26 and Cx30, share widespread expression in the cochlear cellular networks. Gap junction channels formed by these connexins have been shown to have different permeability profiles, with Cx30 showing a strongly reduced preference for anionic tracers. The pore-forming segment of the first extracellular loop, E1, identified by computational studies of the Cx26 crystal structure to form a parahelix and a narrowed region of the pore, differs at a single residue at position 49. Cx26 contains an Ala and Cx30, a charged Glu at this position, and cysteine scanning in hemichannels identified this position to be pore-lining. To assess whether the Ala/Glu difference affects permeability, we modeled and quantified Lucifer Yellow transfer between HeLa cell pairs expressing WT Cx26 and Cx30 and variants that reciprocally substituted Glu and Ala at position 49. Cx26(A49E) and Cx30(E49A) substitutions essentially reversed the Lucifer Yellow permeability profile when accounting for junctional conductance. Moreover, by using a calcein efflux assay in single cells, we observed a similar reduced anionic preference in undocked Cx30 hemichannels and a reversal with reciprocal Ala/Glu substitutions. Thus, our data indicate that Cx26 and Cx30 gap junction channels and undocked hemichannels retain similar permeability characteristics and that a single residue difference in their E1 domains can largely account for their differential permeabilities to anionic tracers. The higher anionic permeability of Cx26 compared with Cx30 suggests that these connexins may serve distinct signaling functions in the cochlea, perhaps reflected in the vastly higher prevalence of Cx26 mutations in human deafness.

Pharmacological targets and validation of remdesivir for the treatment of COVID-19-associated pulmonary fibrosis: A network-based pharmacology and bioinformatics study.

The objective of this study was to employ bioinformatics and network pharmacology methodologies to investigate the targets and molecular mechanisms of remdesivir in the treatment of coronavirus disease 2019 (COVID-19)-associated pulmonary fibrosis (PF). Several open-source databases were utilized to confirm the shared targets of remdesivir, COVID-19, and PF. Following this, a comprehensive analysis incorporating function enrichment, protein-protein interaction (PPI), transcription factor (TF), and molecular docking was conducted to investigate the potential mechanisms underlying the effectiveness of remdesivir in the treatment of COVID-19-associated PF. The initial validation of these findings was performed using publicly available histological and single-cell sequencing databases. The functional enrichment analysis revealed a strong association between remdesivir and viral defense, inflammatory response, and immune response. The key pathways identified in the study were transforming growth factor (TGF-ß), PI3K-Akt, mTOR, MAPK, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor resistance, HIF-1, and Toll-like receptor signaling pathways. Additionally, the PPI analysis demonstrated the network relationships of 13 important targets, while the TF analysis provided valuable insights into the regulatory networks of these targets. Among the identified TFs, RELA was found to be the most significant. To validate our findings, we utilized publicly available histological and single-cell sequencing databases, successfully confirming the involvement of 8 key targets, including AKT1, EGFR, RHOA, MAPK1, PIK3R1, MAPK8, MAPK14, and MTOR. Furthermore, molecular docking studies were conducted to assess the interaction between remdesivir and the identified key targets, thus confirming its effective targeting effects. Remdesivir has the potential to exert antiviral, anti-inflammatory, and immunomodulatory effects in the context of COVID-19-associated PF.

Current status and clinical outcomes of pharmacotherapies according to SARS-CoV-2 mutations in patients with mild-to-moderate COVID-19: a retrospective single center study.

BACKGROUND: During the pandemic period, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mutated, leading to changes in the disease's severity and the therapeutic effect of drugs accordingly. This study aimed to present the actual use of therapeutics and clinical outcomes based on the prevalence of each variant using real-world data. METHODS: We analyzed the electronic medical records of adult patients admitted to Busan Medical Center after confirming coronavirus disease 2019 (COVID-19) from February 1, 2020, to June 30, 2022. Patients with mild-to-moderate COVID-19 who were at a high risk of disease progression were selected as study subjects, and the time period was classified according to the variants as ancestral strain, Delta variant, or Omicron variant. We compared drug use status and clinical outcomes by time period. RESULTS: Among all 3,091 patients, corticosteroids were the most commonly used therapy (56.0%), being used most frequently in the Delta variant (93.0%), followed by the Omicron variant (42.9%) and ancestral strain (21.2%). Regdanvimab accounted for the majority of therapeutic use in the Delta variant (82.9%) and ancestral strain (76.8%), whereas remdesivir was most frequently used during the Omicron variant period (68.9%). The composite outcomes of death or disease aggravation were ranked in the order of the Delta variant, Omicron variant, and ancestral strain (14.5, 11.9, and 6.0%, respectively, P < 0.001). CONCLUSION: Regdanvimab was primarily used during the ancestral strain period, regdanvimab plus corticosteroids during the Delta variant period, and remdesivir during the Omicron variant period. The rate of death or disease aggravation was highest in the Delta variant, followed by the Omicron variant and the ancestral strain.

SARS-CoV-2 viral load is linked to remdesivir efficacy in severe Covid-19 admitted to intensive care.

Remdesivir therapy has been declared as efficient in the early stages of Covid-19. Of the 339 patients (males 55.8%, age 71(59;77) years) with a detectable viral load, 140 were treated with remdesivir (of those 103 in the ICU and 57 immunosuppressed) and retrospectively compared with 199 patients (of those 82 in the ICU and 28 immunosuppressed) who were denied therapy due to advanced Covid-19. The viral load was estimated by detecting nucleocapsid antigen in serum (n = 155, median 217(28;1524)pg/ml), antigen in sputum (n = 18, COI 18(4.6;32)), nasopharyngeal antigen (n = 44, COI 17(8;35)) and the real-time PCR (n = 122, Ct 21(18;27)). After adjustment for confounders, patients on remdesivir had better 12-month survival (HR 0.66 (0.44;0.98), p = 0.039), particularly when admitted to the ICU (HR 0.49 (0.29;0.81), p = 0.006). For the immunocompromised patients, the difference did not reach statistical significance (HR 0.55 (0.18;1.69), p = 0.3). The other most significant confounders were age, ICU admission, mechanical ventilation, leukocyte/lymphocyte ratio, admission creatinine and immunosuppression. The impact of monoclonal antibodies or previous vaccinations was not significant. Despite frequent immune suppression including haemato-oncology diseases, lymphopenia, and higher inflammatory markers in the remdesivir group, the results support remdesivir administration with respect to widely available estimates of viral load in patients with high illness severity.

UPLC-PDA factorial design assisted method for simultaneous determination of oseltamivir, dexamethasone, and remdesivir in human plasma.

A green and simple UPLC method was developed and optimized, adopting a factorial design for simultaneous determination of oseltamivir phosphate and remdesivir with dexamethasone as a co-administered drug in human plasma and using daclatasvir dihydrochloride as an internal standard within 5 min. The separation was established on UPLC column BEH C18 1.7 µm (2.1 × 100.0 mm) connected to UPLC pre-column BEH 1.7 µm (2.1 × 5.0 mm) at 50 °C with an injection volume of 10 µL. The photodiode array detector (PDA) was set at three wavelengths of 220, 315, and 245 nm for oseltamivir phosphate, the internal standard, and both dexamethasone and remdesivir, respectively. The mobile phase consisted of methanol and ammonium acetate solution (40 mM) adjusted to pH 4 in a ratio of 61.5:38.5 (v/v) with a flow rate of 0.25 mL min-1. The calibration curves were linear over 500.0-5000.0 ng mL-1 for oseltamivir phosphate, over 10.0-500.0 ng mL-1 and 500.0-5000.0 ng mL-1 for dexamethasone, and over 20.0-500 ng mL-1 and 500.0-5000.0 ng mL-1 for remdesivir. The Gibbs free energy and Van't Hoff plots were used to investigate the effect of column oven temperatures on retention times. Fluoride-EDTA anticoagulant showed inhibition activity on the esterase enzyme in plasma. The proposed method was validated according to the M10 ICH, FDA, and EMA's bioanalytical guidelines. According to Eco-score, GAPI, and AGREE criteria, the proposed method was considered acceptable green.

Safety of remdesivir in the treatment of acute SARS-CoV-2 infection in pediatric patients.

BACKGROUND: Transaminase and creatinine elevations have been well described in adults treated with remdesivir for COVID-19. It is hypothesized that a similar safety profile exists in children with COVID-19 treated with remdesivir, but available data are limited, especially in children < 12 months. The primary aim of this study was to determine the prevalence and timing of elevations in transaminases and creatinine in children with COVID-19 who were treated with remdesivir. METHODS: This was a retrospective, observational cohort study including all pediatric patients admitted to a single, freestanding children's hospital who were positive for COVID-19 and received at least 1 dose of remdesivir between 1/1/2020 and 5/31/2022. Available baseline and peak transaminase and creatinine concentrations were evaluated. Multivariable logistic regression analysis was performed to identify risk factors for transaminase elevation. RESULTS: A total of 180 patients met inclusion criteria. Creatinine elevation of any grade was noted in 16% and remained elevated only in those with underlying chronic kidney disease. Transaminase elevation of any grade was noted in 58% of patients and remained elevated in only 1%. Older age and critical respiratory disease were associated with higher risk of significant transaminase elevation, whereas non-Hispanic ethnicity was strongly associated with protection against significant transaminase elevation. CONCLUSIONS: In our cohort of hospitalized children with COVID-19 who were treated with remdesivir, most patients experienced only mild transaminitis and normal creatinine concentrations. A limited number of patients experienced laboratory abnormalities which were transient, suggesting a favorable safety profile for remdesivir use in pediatrics.

Potential of 6'­hydroxy justicidin B from Justicia procumbens as a therapeutic agent against coronavirus disease 2019.

BACKGROUND: Since the onset of the coronavirus disease 2019 (COVID-19) pandemic, remarkable advances have been made in vaccine development to reduce mortality. However, therapeutic interventions for COVID-19 are comparatively limited despite these intensive efforts. Furthermore, the rapid mutation capability of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a characteristic of its RNA structure, has led to the emergence of multiple variants, necessitating a shift from a predominantly vaccine-centric approach to one that encompasses therapeutic strategies. 6'-Hydroxy justicidin B (6'-HJB), an arylnaphthalene lignan isolated from Justicia procumbens, a traditional Chinese medicine, is known for its antiviral properties. HYPOTHESIS/PURPOSE: The aim of the present study was to assess the effectiveness and safety of 6'-HJB against SARS-CoV-2 in order to determine its potential as a therapeutic agent against COVID-19. METHODS: The efficacy of 6'-HJB was evaluated both in vitro using Vero and Calu-3 cell lines and in vivo using ferrets. The safety assessment included toxicokinetics, safety pharmacology, and Good Laboratory Practice (GLP)-compliant toxicity evaluations following single- and repeated-dose toxicity studies in dogs. RESULTS: The anti-SARS-CoV-2 efficacy of 6'-HJB was evaluated through dose-response curve (DRC) analysis using immunofluorescence; 6'-HJB demonstrated superior inhibition of SARS-CoV-2 growth and lower cytotoxicity than remdesivir. In SARS-CoV-2-infected ferret, 6'-HJB showed efficacy comparable to that of the positive control, Truvada. Further GLP toxicity studies corroborated the safety profile of 6'-HJB. Single-dose and 4-week repeated oral toxicity studies in Beagle dogs demonstrated minimal harmful effects at the highest dosages. The lethal dose of 6'-HJB exceeded 2,000 mg kg-1 in Beagle dogs. Toxicokinetic and GLP safety pharmacology studies demonstrated no adverse effects of 6'-HJB on metabolic processes, respiratory or central nervous systems, or cardiac functions. CONCLUSION: This research highlights both the antiviral efficacy and safety profile of 6'-HJB, underscoring its potential as a novel COVID-19 treatment option. The potential of 6'-HJB was demonstrated using modern scientific methodologies and standards.

Heterologous Biosynthesis of New Lanthipeptides Nocardiopeptins with an Unprecedented Bridging Pattern of Lanthionine and Labionin.

The class III lanthipeptide synthetase (LanKC) installs unusual amino acids, such as lanthionine and labionin, in lanthipeptides. Through genome mining, we discovered a new class III lanthipeptide synthetase coding gene (nptKC) and precursor peptide coding genes (nptA1, nptA2, and nptA3) in the genome of the actinobacterium Nocardiopsis alba. Coexpression experiments of the biosynthetic genes in Escherichia coli resulted in the production of new lanthipeptides named nocardiopeptins A1-A3. Analysis of two-dimensional NMR spectra after enzymatic degradation and partial basic hydrolysis of nocardiopeptin A2 revealed that labionin was located in lanthionine with opposite orientations, forming a nesting structure in nocardiopeptin A2. To the best of our knowledge, this bridging pattern in the lanthipeptides was unprecedented, indicating a novel reaction characteristic of the class III lanthipeptide synthetase NptKC.

Emerging SARS-CoV-2 Resistance After Antiviral Treatment.

Importance: Previous studies have identified mutations in SARS-CoV-2 strains that confer resistance to nirmatrelvir, yet how often this resistance arises and its association with posttreatment virologic rebound is not well understood. Objective: To examine the prevalence of emergent antiviral resistance after nirmatrelvir treatment and its association with virologic rebound. Design, Setting, and Participants: This cohort study enrolled outpatient adults with acute COVID-19 infection from May 2021 to October 2023. Participants were divided into those who received antiviral therapy and those who did not. The study was conducted at a multicenter health care system in Boston, Massachusetts. Exposure: Treatment regimen, including none, nirmatrelvir, and remdesivir. Main Outcomes and Measures: The primary outcome was emergent SARS-CoV-2 antiviral resistance, defined as the detection of antiviral resistance mutations, which were not present at baseline, were previously associated with decreased antiviral efficacy, and emerged during or after completion of a participant's treatment. Next-generation sequencing was used to detect low frequency mutations down to 1% of the total viral population. Results: Overall, 156 participants (114 female [73.1%]; median [IQR] age, 56 [38-69] years) were included. Compared with 63 untreated individuals, the 79 who received nirmatrelvir were older and more commonly immunosuppressed. After sequencing viral RNA from participants' anterior nasal swabs, nirmatrelvir resistance mutations were detected in 9 individuals who received nirmatrelvir (11.4%) compared with 2 of those who did not (3.2%) (P = .09). Among the individuals treated with nirmatrelvir, those who were immunosuppressed had the highest frequency of resistance emergence (5 of 22 [22.7%]), significantly greater than untreated individuals (2 of 63 [3.1%]) (P = .01). Similar rates of nirmatrelvir resistance were found in those who had virologic rebound (3 of 23 [13.0%]) vs those who did not (6 of 56 [10.7%]) (P = .86). Most of these mutations (10 of 11 [90.9%]) were detected at low frequencies (<20% of viral population) and reverted to the wild type at subsequent time points. Emerging remdesivir resistance mutations were only detected in immunosuppressed individuals (2 of 14 [14.3%]) but were similarly low frequency and transient. Global Initiative on Sharing All Influenza Data analysis showed no evidence of increased nirmatrelvir resistance in the United States after the authorization of nirmatrelvir. Conclusions and Relevance: In this cohort study of 156 participants, treatment-emergent nirmatrelvir resistance mutations were commonly detected, especially in individuals who were immunosuppressed. However, these mutations were generally present at low frequencies and were transient in nature, suggesting a low risk for the spread of nirmatrelvir resistance in the community with the current variants and drug usage patterns.

Predicting Mutation-Induced Allosteric Changes in Structures and Conformational Ensembles of the ABL Kinase Using AlphaFold2 Adaptations with Alanine Sequence Scanning.

Despite the success of AlphaFold2 approaches in predicting single protein structures, these methods showed intrinsic limitations in predicting multiple functional conformations of allosteric proteins and have been challenged to accurately capture the effects of single point mutations that induced significant structural changes. We examined several implementations of AlphaFold2 methods to predict conformational ensembles for state-switching mutants of the ABL kinase. The results revealed that a combination of randomized alanine sequence masking with shallow multiple sequence alignment subsampling can significantly expand the conformational diversity of the predicted structural ensembles and capture shifts in populations of the active and inactive ABL states. Consistent with the NMR experiments, the predicted conformational ensembles for M309L/L320I and M309L/H415P ABL mutants that perturb the regulatory spine networks featured the increased population of the fully closed inactive state. The proposed adaptation of AlphaFold can reproduce the experimentally observed mutation-induced redistributions in the relative populations of the active and inactive ABL states and capture the effects of regulatory mutations on allosteric structural rearrangements of the kinase domain. The ensemble-based network analysis complemented AlphaFold predictions by revealing allosteric hotspots that correspond to state-switching mutational sites which may explain the global effect of regulatory mutations on structural changes between the ABL states. This study suggested that attention-based learning of long-range dependencies between sequence positions in homologous folds and deciphering patterns of allosteric interactions may further augment the predictive abilities of AlphaFold methods for modeling of alternative protein sates, conformational ensembles and mutation-induced structural transformations.

Introducing Chemoselective Peptide Conjugation via N-Alkylation of Pyridyl-alanine: Solution and Solid Phase Applications.

A novel chemoselective peptide conjugation via late-stage N-alkylation of pyridyl-alanine (PAL) in the solution and solid phase, namely, NAP, is demonstrated. The method constructs functionally diverse and highly stable N-alkylated conjugates with various peptides. Notably, conjugations in the solid phase offered a more economical process. The method can provide the opportunity for dual labeling along with a cysteine handle in a peptide chain. Finally, we showcased that the antiproliferative activities of the p53 peptide (MDM2 inhibitor) could be 2-fold enhanced via NAP conjugation with the RGD peptide (selective integrin binder).

Effectiveness and safety of tenofovir amibufenamide in chronic hepatitis B patients.

This letter to the editor relates to the study entitled "Tenofovir amibufenamide vs tenofovir alafenamide for treating chronic hepatitis B: A real-world study", which was recently published by Peng et al. Hepatitis B virus infection represents a significant health burden worldwide and can lead to cirrhosis and even liver cancer. The antiviral drugs currently used to treat patients with chronic hepatitis B infection still have many side effects, so it is crucial to identify safe and effective drugs to inhibit viral replication.

A versatile yeast model identifies the pesticides cymoxanil and metalaxyl as risk factors for synucleinopathies.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons and the presence of Lewy bodies, which predominantly consist of aggregated forms of the protein alpha-synuclein (aSyn). While these aggregates are a pathological hallmark of PD, the etiology of most cases remains elusive. Although environmental risk factors have been identified, such as the pesticides dieldrin and MTPT, many others remain to be assessed and their molecular impacts are underexplored. This study aimed to identify pesticides that could enhance aSyn aggregation using a humanized yeast model expressing aSyn fused to GFP as a primary screening platform, which we validated using dieldrin. We found that the pesticides cymoxanil and metalaxyl induce aggregation of aSyn in yeast, which we confirmed also occurs in a model of aSyn inclusion formation using human H4 cells. In conclusion, our approach generated invaluable molecular data on the effect of pesticides, therefore providing insights into mechanisms associated with the onset and progression of PD and other synucleinopathies.

RNA replication-independent, DNA linearization-dependent expression of reporter genes from a SARS-CoV-2 replicon-encoding DNA in human cells.

Replicons, derived from RNA viruses, are genetic constructs retaining essential viral enzyme genes while lacking key structural protein genes. Upon introduction into cells, the genes carried by the replicon RNA are expressed, and the RNA self-replicates, yet viral particle production does not take place. Typically, RNA replicons are transcribed in vitro and are then electroporated in cells. However, it would be advantageous for the replicon to be generated in cells following DNA transfection instead of RNA. In this study, a bacterial artificial chromosome (BAC) DNA encoding a SARS-CoV-2 replicon under control of a T7 promoter was transfected into HEK293T cells engineered to functionally express the T7 RNA polymerase (T7 RNAP). Upon transfection of the BAC DNA, we observed low, but reproducible expression of reporter proteins GFP and luciferase carried by this replicon. Expression of the reporter proteins required linearization of the BAC DNA prior to transfection. Moreover, expression occurred independently of T7 RNAP. Gene expression was also insensitive to remdesivir treatment, suggesting that it did not involve self-replication of replicon RNA. Similar results were obtained in highly SARS-CoV-2 infection-permissive Calu-3 cells. Strikingly, prior expression of the SARS-CoV-2 N protein boosted expression from transfected SARS-CoV-2 RNA replicon but not from the replicon BAC DNA. In conclusion, transfection of a large DNA encoding a coronaviral replicon led to reproducible replicon gene expression through an unidentified mechanism. These findings highlight a novel pathway toward replicon gene expression from transfected replicon cDNA, offering valuable insights for the development of methods for DNA-based RNA replicon applications.

Mechanistic insights into lanthipeptide modification by a distinct subclass of LanKC enzyme that forms dimers.

Naturally occurring lanthipeptides, peptides post-translationally modified by various enzymes, hold significant promise as antibiotics. Despite extensive biochemical and structural studies, the events preceding peptide modification remain poorly understood. Here, we identify a distinct subclass of lanthionine synthetase KC (LanKC) enzymes with distinct structural and functional characteristics. We show that PneKC, a member of this subclass, forms a dimer and possesses GTPase activity. Through three cryo-EM structures of PneKC, we illustrate different stages of peptide PneA binding, from initial recognition to full binding. Our structures show the kinase domain complexed with the PneA core peptide and GTPγS, a phosphate-bound lyase domain, and an unconventional cyclase domain. The leader peptide of PneA interact with a gate loop, transitioning from an extended to a helical conformation. We identify a dimerization hot spot and propose a "negative cooperativity" mechanism toggling the enzyme between tense and relaxed conformation. Additionally, we identify an important salt bridge in the cyclase domain, differing from those in in conventional cyclase domains. These residues are highly conserved in the LanKC subclass and are part of two signature motifs. These results unveil potential differences in lanthipeptide modification enzymes assembly and deepen our understanding of allostery in these multifunctional enzymes.

Real-world evaluation of early remdesivir in high-risk COVID-19 outpatients during Omicron including BQ.1/BQ.1.1/XBB.1.5.

BACKGROUND: A trial performed among unvaccinated, high-risk outpatients with COVID-19 during the delta period showed remdesivir reduced hospitalization. We used our real-world data platform to determine the effectiveness of remdesivir on reducing 28-day hospitalization among outpatients with mild-moderate COVID-19 during an Omicron period including BQ.1/BQ.1.1/XBB.1.5. METHODS: We did a propensity-matched, retrospective cohort study of non-hospitalized adults with SARS-CoV-2 infection between April 7, 2022, and February 7, 2023. Electronic healthcare record data from a large health system in Colorado were linked to statewide vaccination and mortality data. We included patients with a positive SARS-CoV-2 test or outpatient remdesivir administration. Exclusion criteria were other SARS-CoV-2 treatments or positive SARS-CoV-2 test more than seven days before remdesivir. The primary outcome was all-cause hospitalization up to day 28. Secondary outcomes included 28-day COVID-related hospitalization and 28-day all-cause mortality. RESULTS: Among 29,270 patients with SARS-CoV-2 infection, 1,252 remdesivir-treated patients were matched to 2,499 untreated patients. Remdesivir was associated with lower 28-day all-cause hospitalization (1.3% vs. 3.3%, adjusted hazard ratio (aHR) 0.39 [95% CI 0.23-0.67], p < 0.001) than no treatment. All-cause mortality at 28 days was numerically lower among remdesivir-treated patients (0.1% vs. 0.4%; aOR 0.32 [95% CI 0.03-1.40]). Similar benefit of RDV treatment on 28-day all-cause hospitalization was observed across Omicron periods, aOR (95% CI): BA.2/BA2.12.1 (0.77[0.19-2.41]), BA.4/5 (0.50[95% CI 0.50-1.01]), BQ.1/BQ.1.1/XBB.1.5 (0.21[95% CI 0.08-0.57]. CONCLUSION: Among outpatients with SARS-CoV-2 during recent Omicron surges, remdesivir was associated with lower hospitalization than no treatment, supporting current National Institutes of Health Guidelines.

An in vitro study for reducing the cytotoxicity and dose dumping risk of remdesivir via entrapment in nanostructured lipid carriers.

The aim of this study was to synthesize and evaluate nanostructured lipid carriers (NLCs) loaded with Remdesivir (RDV) to control its side effects in COVID-19 patients. Due to the low solubility and short half-life of RDV in the blood, an injectable formulation was prepared using sulphobutylether-beta-cyclodextrin. However, it can accumulate in the kidney and cause renal impairment. NLCs improve the parenteral delivery of hydrophobic drugs such as RDV by increasing drug solubility and bioavailability. For the synthesis of RDV-NLCs, the aqueous phase containing Tween 80 was injected into the lipid phase under rapid stirring and was sonicated. The experimental conditions were optimized using Box-Behnken design and Design Expert software. The optimum formulation contained a total lipid of 2.13%, a total surfactant of 1%, and a hot bath time of 71 min. The optimum formulation showed particle size, polydispersity index, zeta potential, and entrapment efficiency values of 151.0 ± 1.7 nm (from 149.1 to 152.1), 0.4 ± 0.1 (from 0.3 to 0.5), -43.8 ± 1.2 mV (from -42.4 to -44.7), and 81.34 ± 1.57% (from 79.52 to 82.33%), respectively. RDV-NLCs showed acceptable stability for 30 days at 25 â„ƒ and were compatible with commonly used intravenous infusion fluids for 48 h. FE-SEM images of RDV-NLC showed spherical particles with a mean diameter of 207 nm. The NLC-RDV formulation showed a sustained release of RDV with a low risk of dose-dumping, minimizing potential side effects. In addition, RDV in the form of RDV-NLC causes less cytotoxicity to healthy normal kidney cells, which is expected to reduce renal impairment in COVID-19 patients.