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The development of a chylothorax after robot-assisted laparoscopic splenectomy combined with pericardial devascularization (LSPD) is rare. The robot-assisted procedure is similar to the standard LSPD, but surgeons must remain vigilant about potential chylothorax caused by recurrence of portal hypertension in patients with cirrhosis, an event that leads to variceal bleeding in the gastric fundus or a massive chylothorax caused by a thoracic duct fistula. We report a rare case of massive chylothorax after robot-assisted LSPD and review the literature to help elucidate the mechanisms of portal hypertension after LSPD, reduce surgical complications, and improve long-term patient outcomes. After LSPD, portal pressure monitoring, coagulation function testing, and portal vein CT imaging help in excluding portal vein thromboses and ensuring appropriate anticoagulation to reduce the development of thoracic duct fistulas. If portal hypertension recurs after surgery and a high-output chylothorax develops, conservative treatment becomes ineffective. Treatment with an active trans-jugular intrahepatic portosystemic shunt (TIPS) is recommended to lower the portal pressure.

CRISPR/Cas9 technology is a highly promising genome editing tool in the mouse, potentially overcoming the costs and time required for more traditional gene targeting methods in embryonic stem (ES) cells. Recently, compared to the wildtype nuclease, paired Cas9 nickase (Cas9n) combined with single guide RNA (sgRNA) molecules has been found to enhance the specificity of genome editing while reducing off-target effects. Paired Cas9n has been shown to be as efficient as Cas9 for generating insertion and deletion (indel) mutations by non-homologous end joining and targeted deletion in the genome. However, an efficient and reliable approach to the insertion of loxP sites flanking critical exon(s) to create a conditional allele of a target gene remains an elusive goal. In this study, we microinjected Cas9n RNA with sgRNAs together with a single DNA template encoding two loxP sites flanking (floxing) exon 2 of the isoprenoid synthase containing domain (Ispd) into the pronucleus and cytoplasm of C57BL/6NCr one-cell stage zygotes. After surgical transfer, one F0 mouse expressing a conditional allele was produced (at a frequency of ∼8% of live pups born). The floxed allele was transmitted through the germline to F1 progeny, and could be successfully recombined using Cre recombinase. This study indicates that conditional targeting can be accomplished effectively using paired Cas9n and a single DNA template.