Assessment of the usefulness of bacterial cellulose produced by Gluconacetobacter xylinus E25 as a new biological implant.

Bionanocellulose (BNC) is a clear polymer produced by the bacterium Gluconacetobacter xylinus. In our current study, "Research on the use of bacterial nanocellulose (BNC) in regenerative medicine as a function of the biological implants in cardiac and vascular surgery", we carried out material analysis, biochemical analysis, in vitro tests and in vivo animal model testing. In stage 1 of the project, we carried out physical and biological tests of BNC. This allowed us to modify subsequent samples of bacterial bionanocellulose. Finally, we obtained a sample that was accepted for testing on an animal model. That sample we define BNC1. Patches of BNC1 were then implanted into pigs' vessel walls. During the surgical procedures, we evaluated the technical aspects of sewing in the bioimplant, paying special attention to bleeding control and tightness of the suture line and the BNC1 bioimplant itself. We carried out studies evaluating the reaction of an animal body to an implantation of BNC1 into the circulatory system, including the general and local inflammatory reaction to the bioimplant. These studies allowed us to document the potential usefulness of BNC as a biological implant of the circulatory system and allowed for additional modifications of the BNC to improve the properties of this new implantable biological material.

Small doses of morphine can enhance NK cell cytotoxicity in pigs.

The effect of small and moderate doses of morphine (MF) on NK cell lytic activity (cytotoxicity, NKCC) ((51)Cr release test) and the number of circulating large granular lymphocytes (LGL) was evaluated in i.v. catheterized Pietrain crossbred pigs. Simultaneously, plasma cortisol (COR) (RIA method) was measured. Blood samples were collected 15, 60, 120, 180, and 240 min after i.v. injections of 0.5, 1.0 and 5.0 mg/kg of MF alone or MF pretreated with naloxone (NX, 1.0 mg/kg, i.v., 15 min before MF). It was found that MF induced dose- and time-dependent changes of NKCC. MF in a dose of 0.5 mg/kg evoked 4-fold increase in NKCC (in comparison to saline) without changes in the number of LGL/NK cells. Higher MF doses (1.0, 5.0 mg/kg) induced an early increase (up to 300Delta% and 29Delta%, respectively) followed by a decrease in cytotoxicity (to -76Delta% after 5.0 mg/kg), and in LGL number (-36Delta% after 5.0 mg/kg). These effects were concomitant with a marked rise in plasma COR (up to 234Delta% after 0.5 mg/kg and 567Delta% after 5.0 mg/kg of MF). NX pretreatment blocked all the changes in cytotoxicity but not in the LGL cell number and COR concentrations. The results indicate that MF, besides having well known immunosuppressive effects, can also enhance NKCC through the opioid receptors-dependent manner. The enhancement of cytotoxicity appears as a purely functional change independent of the recirculation of NK cells which occurs despite the high plasma concentrations of COR.