Management of Acute Appendicitis During the COVID-19 Pandemic: A Single-Centre Retrospective Cohort Study.

BACKGROUND: During the coronavirus disease 2019 (COVID-19) pandemic, the management of acute appendicitis shifted towards non-operative management in the United Kingdom (UK). The open approach was recommended over the laparoscopic approach due to the risk of aerosol generation and subsequent contamination. The aim of this study was to compare the overall management and surgical outcomes of the patients treated for acute appendicitis before and during the COVID-19 pandemic. MATERIALS AND METHODS: We performed a retrospective cohort study at a single district general hospital in the UK. We compared the management and outcome of the patients diagnosed with acute appendicitis before the pandemic, from March to August 2019, and during the pandemic, from March to August 2020. We looked at the patient demographics, methods of diagnosis, management, and surgical outcomes for these patients. The primary outcome of the study was the 30-day readmission rate. Secondary outcomes included length of stay and post-operative complications. RESULTS: Over the period of six months, a total of 179 patients were diagnosed with acute appendicitis in 2019 (Pre-COVID-19 pandemic, from March 1, 2019, to August 31, 2019) versus 152 in 2020 (during the COVID-19 pandemic, from March 1, 2020, to August 31, 2020). For the 2019 cohort, the mean age of the patients was 33 (range 6-86 years), 52% (n=93) were female, and the mean BMI was 26 (range 14-58). For the 2020 cohort, the mean age was 37 (range 4-93 years), 48% (n=73) of the patients were female, and the mean BMI was 27 (range 16-53). At the first presentation, in 2019, 97.2% of the patients (174 out of 179) received surgical treatment compared to 70.4% (107 out of 152) in 2020. Three per cent of the patients (n=5) were managed conservatively in 2019 (two out these failed conservative management) as compared to 29.6% (n=45) in 2020 (21 of these failed conservative management). Pre-pandemic, only 32.4% (n= 57, ultrasound (US) scan: 11, computer tomography (CT) scan): 45, both US and CT: 1) of the patients received imaging to confirm the diagnosis as compared to 53.3% during pandemic (n=81, US scan: 12, CT scan: 63, both US and CT: 6). Overall, the CT to US ratio increased. We found that during 2019, 91.5% (n=161/176) of the patients who received surgical treatment went through laparoscopic surgery as compared to only 74.2% (n=95/128) in 2020 (p<0.0001). Postoperative complications occurred in 5.1% (n=9/176) of the surgical patients in 2019 as compared to 12.5% (n=16/128) in 2020 (p<0.033). The mean length of hospital stay in 2019 was 2.9 days (range 1-11) versus 4.5 days in 2020 (range 1-57) (p<0.0001). The 30-day readmission rate was 4.5% (8/179) versus 19.1% (29/152) (p<0.0001). The 90-day mortality rate was zero for both cohorts. CONCLUSION: Our study shows that the management of acute appendicitis changed due to the COVID-19 pandemic. More patients went through imaging, especially CT scans for diagnosis and received non-operative management with antibiotics only. The open surgical approach became more common during the pandemic. This was associated with longer lengths of hospital stay, more readmissions, and an increase in postoperative complications.

Identification of SARS-CoV-2-induced pathways reveals drug repurposing strategies.

The global outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) necessitates the rapid development of new therapies against coronavirus disease 2019 (COVID-19) infection. Here, we present the identification of 200 approved drugs, appropriate for repurposing against COVID-19. We constructed a SARS-CoV-2-induced protein network, based on disease signatures defined by COVID-19 multiomics datasets, and cross-examined these pathways against approved drugs. This analysis identified 200 drugs predicted to target SARS-CoV-2-induced pathways, 40 of which are already in COVID-19 clinical trials, testifying to the validity of the approach. Using artificial neural network analysis, we classified these 200 drugs into nine distinct pathways, within two overarching mechanisms of action (MoAs): viral replication (126) and immune response (74). Two drugs (proguanil and sulfasalazine) implicated in viral replication were shown to inhibit replication in cell assays. This unbiased and validated analysis opens new avenues for the rapid repurposing of approved drugs into clinical trials.

Current and prospective computational approaches and challenges for developing COVID-19 vaccines.

SARS-CoV-2, which causes COVID-19, was first identified in humans in late 2019 and is a coronavirus which is zoonotic in origin. As it spread around the world there has been an unprecedented effort in developing effective vaccines. Computational methods can be used to speed up the long and costly process of vaccine development. Antigen selection, epitope prediction, and toxicity and allergenicity prediction are areas in which computational tools have already been applied as part of reverse vaccinology for SARS-CoV-2 vaccine development. However, there is potential for computational methods to assist further. We review approaches which have been used and highlight additional bioinformatic approaches and PK modelling as in silico methods which may be useful for SARS-CoV-2 vaccine design but remain currently unexplored. As more novel viruses with pandemic potential are expected to arise in future, these techniques are not limited to application to SARS-CoV-2 but also useful to rapidly respond to novel emerging viruses.

SHOC2 complex-driven RAF dimerization selectively contributes to ERK pathway dynamics.

Despite the crucial role of RAF kinases in cell signaling and disease, we still lack a complete understanding of their regulation. Heterodimerization of RAF kinases as well as dephosphorylation of a conserved "S259" inhibitory site are important steps for RAF activation but the precise mechanisms and dynamics remain unclear. A ternary complex comprised of SHOC2, MRAS, and PP1 (SHOC2 complex) functions as a RAF S259 holophosphatase and gain-of-function mutations in SHOC2, MRAS, and PP1 that promote complex formation are found in Noonan syndrome. Here we show that SHOC2 complex-mediated S259 RAF dephosphorylation is critically required for growth factor-induced RAF heterodimerization as well as for MEK dissociation from BRAF. We also uncover SHOC2-independent mechanisms of RAF and ERK pathway activation that rely on N-region phosphorylation of CRAF. In DLD-1 cells stimulated with EGF, SHOC2 function is essential for a rapid transient phase of ERK activation, but is not required for a slow, sustained phase that is instead driven by palmitoylated H/N-RAS proteins and CRAF. Whereas redundant SHOC2-dependent and -independent mechanisms of RAF and ERK activation make SHOC2 dispensable for proliferation in 2D, KRAS mutant cells preferentially rely on SHOC2 for ERK signaling under anchorage-independent conditions. Our study highlights a context-dependent contribution of SHOC2 to ERK pathway dynamics that is preferentially engaged by KRAS oncogenic signaling and provides a biochemical framework for selective ERK pathway inhibition by targeting the SHOC2 holophosphatase.

SHOC2 phosphatase-dependent RAF dimerization mediates resistance to MEK inhibition in RAS-mutant cancers.

Targeted inhibition of the ERK-MAPK pathway, upregulated in a majority of human cancers, has been hindered in the clinic by drug resistance and toxicity. The MRAS-SHOC2-PP1 (SHOC2 phosphatase) complex plays a key role in RAF-ERK pathway activation by dephosphorylating a critical inhibitory site on RAF kinases. Here we show that genetic inhibition of SHOC2 suppresses tumorigenic growth in a subset of KRAS-mutant NSCLC cell lines and prominently inhibits tumour development in autochthonous murine KRAS-driven lung cancer models. On the other hand, systemic SHOC2 ablation in adult mice is relatively well tolerated. Furthermore, we show that SHOC2 deletion selectively sensitizes KRAS- and EGFR-mutant NSCLC cells to MEK inhibitors. Mechanistically, SHOC2 deletion prevents MEKi-induced RAF dimerization, leading to more potent and durable ERK pathway suppression that promotes BIM-dependent apoptosis. These results present a rationale for the generation of SHOC2 phosphatase targeted therapies, both as a monotherapy and to widen the therapeutic index of MEK inhibitors.