Inhibition of canine distemper virus replication by blocking pyrimidine nucleotide synthesis with A77 1726, the active metabolite of the anti-inflammatory drug leflunomide.

Canine distemper virus (CDV) is the aetiological agent that causes canine distemper (CD). Currently, no antiviral drugs have been approved for CD treatment. A77 1726 is the active metabolite of the anti-rheumatoid arthritis (RA) drug leflunomide. It inhibits the activity of Janus kinases (JAKs) and dihydroorotate dehydrogenase (DHO-DHase), a rate-limiting enzyme in de novo pyrimidine nucleotide synthesis. A77 1726 also inhibits the activity of p70 S6 kinase (S6K1), a serine/threonine kinase that phosphorylates and activates carbamoyl-phosphate synthetase (CAD), a second rate-limiting enzyme in the de novo pathway of pyrimidine nucleotide synthesis. Our present study focuses on the ability of A77 1726 to inhibit CDV replication and its underlying mechanisms. Here we report that A77 1726 decreased the levels of the N and M proteins of CDV and lowered the virus titres in the conditioned media of CDV-infected Vero cells. CDV replication was not inhibited by Ruxolitinib (Rux), a JAK-specific inhibitor, but by brequinar sodium (BQR), a DHO-DHase-specific inhibitor, and PF-4708671, an S6K1-specific inhibitor. Addition of exogenous uridine, which restores intracellular pyrimidine nucleotide levels, blocked the antiviral activity of A77 1726, BQR and PF-4708671. A77 1726 and PF-4708671 inhibited the activity of S6K1 in CDV-infected Vero cells, as evidenced by the decreased levels of CAD and S6 phosphorylation. S6K1 knockdown suppressed CDV replication and enhanced the antiviral activity of A77 1726. These observations collectively suggest that the antiviral activity of A77 1726 against CDV is mediated by targeting pyrimidine nucleotide synthesis via inhibiting DHO-DHase activity and S6K1-mediated CAD activation.

Export priority technique for Uni-portal thoracoscopic left upper lobectomy.

BACKGROUND: Further explore the safety and feasibility of Uni-portal video assisted thoracoscopic (UVATS) left upper lobectomy by optimizing the treatment of incisions and blood vessels. METHODS: We conducted a retrospective analysis of data from 32 patients who underwent UVATS left upper lobectomy and systematic mediastinal lymph node dissection utilizing the Export priority technique between January 2021 and December 2022. We documented perioperative indicators, including surgical time, intraoperative blood loss, the number of lymph nodes dissected, and postoperative pathological staging. RESULTS: All surgeries were conducted utilizing the Export priority technique in UVATS. The mean surgical duration was (98.93 ± 14.98) minutes, with an average intraoperative blood loss of (79.53 ± 37.96) ml. The mean count of dissected lymph nodes was (13.96 ± 2.69). The length of hospital Stay averaged (5.62 ± 1.81) days. On the first postoperative day, the thoracic drainage volume was (101.87 ± 49.46) ml. The mean duration of postoperative thoracic tube insertion was (3.1 ± 1.84) days. No occurrences of postoperative hoarseness, pulmonary infection, or complications such as bronchopleural fistula were observed. CONCLUSION: The application of the Export priority technique improves the safety and feasibility of UVATS left upper lobectomy.