A rat model of dual-flow liver machine perfusion system.

PURPOSE: As clinical liver perfusion systems use portal vein and artery flow, dual perfusion techniques are required even in small animal models in order to reproduce clinical setting. The aim of this study was to construct a new dual-flow perfusion system in rat model and optimized the oxygen supply to ensure the aerobic metabolization. METHODS: The dual-flow circuit was fabricated using rat liver and whole blood samples as perfusates. The oxygen supply was controlled according to the amount of dissolved oxygen in the perfusate. Perfusate parameters and adenosine triphosphate (ATP) levels were analyzed to evaluate organ function and metabolic energy state. Stored whole blood also tested the suitability as perfusate. RESULTS: Stored blood showed decrease oxygen delivery and liver function compared to fresh blood. Using fresh blood as perfusate with air only, the dissolved oxygen levels remained low and anaerobic metabolism increased. In contrast, with oxygen control at living body level, anaerobic metabolism was well suppressed, and tissue ATP content was increased. CONCLUSIONS: We developed a new dual-flow system that enable to reproduce the clinical settings. The perfusion system showed the possibility to improve the energy metabolic state of the perfused organ under appropriate partial pressure of oxygen.

A rat model of dual-flow liver machine perfusion system

Purpose: As clinical liver perfusion systems use portal vein and artery flow, dual perfusion techniques are required even in small animal models in order to reproduce clinical setting. The aim of this study was to construct a new dual-flow perfusion system in rat model and optimized the oxygen supply to ensure the aerobic metabolization. Methods: The dual-flow circuit was fabricated using rat liver and whole blood samples as perfusates. The oxygen supply was controlled according to the amount of dissolved oxygen in the perfusate. Perfusate parameters and adenosine triphosphate (ATP) levels were analyzed to evaluate organ function and metabolic energy state. Stored whole blood also tested the suitability as perfusate. Results: Stored blood showed decrease oxygen delivery and liver function compared to fresh blood. Using fresh blood as perfusate with air only, the dissolved oxygen levels remained low and anaerobic metabolism increased. In contrast, with oxygen control at living body level, anaerobic metabolism was well suppressed, and tissue ATP content was increased. Conclusions: We developed a new dual-flow system that enable to reproduce the clinical settings. The perfusion system showed the possibility to improve the energy metabolic state of the perfused organ under appropriate partial pressure of oxygen.

Cloning of the gene cluster responsible for the biosynthesis of brasilicardin A, a unique diterpenoid.

Brasilicardin A (BCA), produced by Nocardia brasiliensis IFM 0406 (currently referred to as N. terpenica), has a unique structure consisting of a diterpene skeleton with L-rhamnose, N-acetylglucosamine, amino acid, and 3-hydroxybenzoate moieties, and exhibits potent biological activities. To understand the biosynthetic machinery of this unique compound, we have cloned the corresponding gene cluster. Firstly, we cloned a gene by PCR that encodes geranylgeranyl diphosphate synthase (GGPPS), which produces a direct precursor of diterpene compounds. We obtained four candidate genes and one of the genes was confirmed to encode a GGPPS. By sequence analysis of regions flanking the GGPPS gene, we identified eleven genes (bra1-11), all oriented in the same direction. We did not, however, detect any genes related to L-rhamnose and N-acetylglucosamine biosyntheses in the flanking regions. A gene disruption experiment did indeed show that this gene cluster was responsible for BCA biosynthesis.