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Purpose: SARS-CoV-2 infection is associated with substantial mortality and high morbidity. This study tested the effect of angiotensin II type I receptor blocker, losartan, on SARS-CoV-2 replication and inhibition of the papain-like protease of the virus. Methods: The dose-dependent inhibitory effect of losartan, in concentrations from 1μM to 100μM as determined by quantitative cell analysis combining fluorescence microscopy, image processing, and cellular measurements (Cellomics analysis) on SARS-CoV-2 replication was investigated in Vero E6 cells. The impact of losartan on deubiquitination and deISGylation of SARS-CoV-2 papain-like protease (PLpro) were also evaluated.  Results: Losartan reduced PLpro cleavage of tetraUbiquitin to diUbiquitin.  It was less effective in inhibiting PLpro’s cleavage of ISG15-AMC than Ubiquitin-AMC.  To determine if losartan inhibited SARS-CoV-2 replication, losartan treatment of SARS-CoV-2 infected Vero E6 was examined. Losartan treatment one hour prior to SARS-CoV-2 infection reduced levels of SARS-CoV-2 nuclear protein, an indicator of virus replication, by 80% and treatment one-hour post-infection decreased viral replication by 70%. Conclusion: Losartan was not an effective inhibitor of deubiquitinase or deISGylase activity of the PLpro but affected the SARS-CoV-2 replication of Vero E6 cells in vitro.  As losartan has a favorable safety profile and is currently available it has features necessary for efficacious drug repurposing and treatment of COVID-19.

PURPOSE: To test and demonstrate measurement precision, imaging resolution, 3D thickness mapping, and clinical utility of a new prototype 3D very high-frequency (VHF) (50 MHz) digital ultrasound scanning system for corneal epithelium, flap, and residual stromal thickness after laser in situ keratomileusis (LASIK). METHODS: VHF ultrasonic 3D data was acquired by arc-motion, meridional scanning within a 10-mm zone. Digital signal processing techniques provided high-resolution B-scan imaging, and I-scan traces for high-precision pachymetry in 4 eyes. Thickness maps of individual corneal layers were constructed. Reproducibility of epithelial, flap, and full corneal pachymetry was assessed for single-point and 3D thickness mapping by repeated measures. Thickness mapping of the epithelium, stroma, flap, and full cornea were determined before and after LASIK. Preoperative to postoperative difference maps for epithelium, flap, and stroma were produced to demonstrate anatomical changes in the thickness profile of each layer. RESULTS: Surface localization precision was 0.87 /im. Central reproducibility for single-point pachymetry of epithelium was 0.61 //m; flap, 1.14 /tra; and full cornea, 0.74 /im. Reproducibility for central pachymetry on 3D thickness mapping was 0.5 µt? for epithelium and 1.5-//m for full cornea. B-scans and 3D thickness maps after LASIK demonstrated resolution of epithelial, stromal component of the flap, and residual stromal layers. Large epithelial profile changes were demonstrated after LASIK. Topographic variability of flap thickness and residual stromal thickness were significant. CONCLUSIONS: VHF digital ultrasound arc-B scanning provides high-resolution imaging and high-precision three-dimensional thickness mapping of corneal layers, enabling accurate anatomical evaluation of the changes induced in the cornea by LASIK. [J Refract Surg 2000;16:414-4301

Since the spread of the deadly virus SARS-CoV-2 in late 2019, researchers have restlessly sought to unravel how the virus enters the host cells. Some proteins on each side of the interaction between the virus and the host cells are involved as the major contributors to this process: (1) the nano-machine spike protein on behalf of the virus, (2) angiotensin converting enzyme II, the mono-carboxypeptidase and the key component of renin angiotensin system on behalf of the host cell, (3) some host proteases and proteins exploited by SARS-CoV-2. In this review, the complex process of SARS-CoV-2 entrance into the host cells with the contribution of the involved host proteins as well as the sequential conformational changes in the spike protein tending to increase the probability of complexification of the latter with angiotensin converting enzyme II, the receptor of the virus on the host cells, are discussed. Moreover, the release of the catalytic ectodomain of angiotensin converting enzyme II as its soluble form in the extracellular space and its positive or negative impact on the infectivity of the virus are considered.

G-protein-coupled receptors (GPCR) belong to a large family of molecules eliciting different responses to a variety of signaling molecules. These receptors participate in various physiologic pathways such as metabolism, growth, immune responses, inflammation, vision, taste, olfaction, neurotransmission and even and pathologic responses including chronic inflammatory and vascular diseases. Receptors contributing to the biological responses of renin-angiotensin system (RAS) are members of GPCR family. COVID-19-induced inflammatory cascade has been attributed to acute ACE2 downregulation and imbalance of proinflammatory ACE/AngII/AT1R and anti-inflammatory ACE2/angiotensin (1-7)/Mas axes in favor of the former. Some of the receptors contributing to activities of proteins in RAS including AT1R, AT2R and Mas receptors are members of GPCR family. It is notable that these receptors induce their effects both through G protein and β-arrestin pathway; the former exerts temporary and the latter more sustained effects. In addition to the imbalance of GPCR responses contributing to RAS activities, it has been suggested that SARS-CoV2 pathogenesis might be attributed to the activation of GPCRs or modulating G-proteins involved in adenosine-CFTR regulation system and epithelial Na channel function.This article includes a minireview about the physiological functions of GPCRs and their contribution to COVID-19.