The relationship of the lock-step phenomenon and precipitous changes in mean arterial blood pressure

The lock-step phenomenon (LSP) is the occurrence of postganglionic cardiac sympathetic discharge (PCSD) and cortical epileptiform activity (EA) in a time-locked fashion. The relationship between the LSP and precipitous changes in blood pressure (PCBP: greater than 23 mm Hg in 10 sec) was determined in 9 cats after EA was induced with pentylenetetrazol following pretreatment with phenobarbital (20 mg/kg, i.v.). Electrocorticogram (ECoG), PCSD, lead II EKG, and mean arterial blood pressure (MAP) were monitored. Since an interspike interval of 2.8 sec was frequently found to exist between ECoG spikes when the LSP was present, 4 categories of LSP were defined: LSP absent; stable LSP with 2.8 sec interval; stable LSP without 2.8 sec interval; and unstable LSP with increasing or decreasing rates of discharge. The duration of each LSP pattern and the proportion of time spent in PCBP were determined. A one-way repeated measures ANOVA and the Newman-Keuls post-hoc test showed that a higher mean proportion of time spent in PCBP was associated with the unstable LSP pattern (P less than 0.05). The LSP and associated patterns as related to precipitous changes in MAP are indicators of changes in autonomic function. Autonomic dysfunction with EA, causing cardiac arrhythmias, has been postulated as a cause of sudden unexplained death (SUD) in persons with epilepsy. Thus, an understanding of the autonomic changes, as indicated by PCBP associated with LSP, may contribute to the understanding and prevention of SUD in persons with epilepsy.

Scalable Inhibitors of the Nsp3-Nsp4 Coupling in SARS-CoV-2

The human Betacoronavirus SARS-CoV-2 is a novel pathogen claiming millions of lives and causing a global pandemic that has disrupted international healthcare systems, economies, and communities. The virus is fast mutating and presenting more infectious but less lethal versions. Currently, some small-molecule therapeutics have received FDA emergency use authorization for the treatment of COVID-19, including Lagevrio (molnupiravir) and Paxlovid (nirmaltrevir/ritonavir), which target the RNA-dependent RNA polymerase and the 3CLpro main protease, respectively. Proteins downstream in the viral replication process, specifically the nonstructural proteins (Nsps1-16), are potential drug targets due to their crucial functions. Of these Nsps, Nsp4 is a particularly promising drug target due to its involvement in the SARS-CoV viral replication and double-membrane vesicle formation (mediated via interaction with Nsp3). Given the degree of sequence conservation of these two Nsps across the Betacoronavirus clade, their protein-protein interactions and functions are likely to be conserved as well in SARS-CoV-2. Through AlphaFold2 and its recent advancements, protein structures were generated of Nsp3 and 4 lumenal loops of interest. Then, using a combination of molecular docking suites and an existing library of lead-like compounds, we virtually screened 7 million ligands to identify five putative ligand inhibitors of Nsp4, which could present an alternative pharmaceutical approach against SARS-CoV-2. These ligands exhibit promising lead-like properties (ideal molecular weight and log P profiles), maintain fixed-Nsp4-ligand complexes in molecular dynamics (MD) simulations, and tightly associate with Nsp4 via hydrophobic interactions. Additionally, alternative peptide inhibitors based on Nsp3 were designed and shown in MD simulations to provide a highly stable binding to the Nsp4 protein. Finally, these therapeutics were attached to dendrimer structures to promote their multivalent binding with Nsp4, especially its large flexible luminal loop (Nsp4LLL). The therapeutics tested in this study represent many different approaches for targeting large flexible protein structures, especially those localized to the ER. This study is the first work targeting the membrane rearrangement system of viruses and will serve as a potential avenue for treating viruses with similar replicative function.

Rational Design of de novo CCL2 Binding Peptides

Chronic levels of inflammation lead to autoimmune diseases such as rheumatoid arthritis and atherosclerosis. A key molecular mediator responsible for the progression of these diseases is Chemokine C-C motif ligand 2 (CCL2), a homodimerized cytokine that dissociates into monomeric form and binds to the CCR2 receptor. CCL2, also known as monocyte chemoattractant protein-1 (MCP-1), attracts monocytes to migrate to areas of injury and mature into macrophages, leading to positive feedback inflammation with further release of proinflammatory molecules such as IL-1β and TNF-α. Sequestering CCL2 to prevent its binding to CCR2 may prevent this inflammatory activity. Prior work adapted an α-helical CCL2-binding peptide (WKNFQTI) from murine CCR2 through extracellular loop analysis. Here, higher-affinity peptide binders were computationally designed through homology modeling and energy calculations, yielding an 11-amino acid peptide with high binding affinity. In addition, Rosetta mutations improved binding affinity in silico with blockage of the CCL2 dimerization site. Future work in analyzing binding kinetics and in vivo inflammation abrogation will confirm the accuracy of computational modeling techniques in de novo rational design of CCL2 cytokine binders.

Correction to "Scalable Inhibitors of the Nsp3-Nsp4 Coupling in SARS-CoV-2"

[This corrects the article DOI: 10.1021/acsomega.2c06384.].

Structural Consequences of Introducing Bioactive Domains to Designer β-Sheet Peptide Self-Assemblies

We applied solid- and solution-state nuclear magnetic resonance spectroscopy to examine the structure of multidomain peptides composed of self-assembling β-sheet domains linked to bioactive domains. Bioactive domains can be selected to stimulate specific biological responses (e.g., via receptor binding), while the β-sheets provide the desirable nanoscale properties. Although previous work has established the efficacy of multidomain peptides, molecular-level characterization is lacking. The bioactive domains are intended to remain solvent-accessible without being incorporated into the β-sheet structure. We tested for three possible anticipated molecular-level consequences of introducing bioactive domains to β-sheet-forming peptides: (1) the bioactive domain has no effect on the self-assembling peptide structure; (2) the bioactive domain is incorporated into the β-sheet nanofiber; and (3) the bioactive domain interferes with self-assembly such that nanofibers are not formed. The peptides involved in this study incorporated self-assembling domains based on the (SL)6 motif and bioactive domains including a VEGF-A mimic (QK), an IGF-mimic (IGF-1c), and a de novo SARS-CoV-2 binding peptide (SBP3). We observed all three of the anticipated outcomes from our examination of peptides, illustrating the unintended structural effects that could adversely affect the desired biofunctionality and biomaterial properties of the resulting peptide hydrogel. This work is the first attempt to evaluate the structural effects of incorporating bioactive domains into a set of peptides unified by a similar self-assembling peptide domain. These structural insights reveal unmet challenges in the design of highly tunable bioactive self-assembling peptide hydrogels.