Evaluation of Collagenase Activity from Crab Hepatopancreas in Different Model Systems.

The effect of Kamchatka crab hepatopancreas containing three collagenolytic isoenzymes Collagenase KK and proteinases of Streptomyces lavendulae on metabolic activity and cell death were carried out on in vitro models. It was shown that changes in the protein structure under the influence of Collagenase KK occurred earlier than under the effect of bacterial proteinases. At the same time, activity of Collagenase KK was significantly higher than that of bacterial proteinases (p<0.01). Both preparations had a pronounced time- and dose-dependent effects on metabolic activity of cells. Collagenase KK had low cytotoxic effect, and cells mainly died by apoptosis. Thus, hepatopancreas collagenase has a high activity and proapoptotic effect on cells and can be used in low concentrations for enzymatic disaggregation of tissues.

Acute Effect of Selective Chemical Inactivation of Sympathetic or Parasympathetic Atrial Ganglionated Plexus Structures on Atrial Fibrillation Inducibility in Pigs.

We studied the role of both parts of the autonomic intracardiac nervous system in the pathogenesis of atrial fibrillation (AF). In 12 pigs weighing 39±3 kg, AF was induced by burst stimulation. Chemical inactivation of intrinsic cardiac neurons within the right atria was performed by transendocardial injections of liposomal neuromodulators into the dorsal part of the right atrial wall. Sympathetic and parasympathetic terminals were inactivated with 6-hydroxydopamine (6-OHDA, n=6) and ethylcholine aziridinium ion (AF64A, n=6), respectively. Neuromodulators were encapsulated in liposomes (LS) with diameters of 310±50 nm for OHDA and 290±50 nm for AF64A. LS-6-OHDA and LS-AF64A were injected into the ganglionated plexuses after measuring the baseline effective refractory period and assessing myocardial resistance to AF. These measurements were repeated 90 min after the injections. The optimal doses were 0.2 mg/kg for LS-6-OHDA and 0.4 mg/kg for LS-AF64A (in 4 ml of suspension). Immediately after injections of liposomal neuromodulators, almost all pigs showed an increase in HR, and a short-term BP elevation was observed in the LS-AF64A group. At the end of the experiment, similar decrease in the effective refractory period and similar increase in the resistance to AF were observed in all animals. Thus, selective chemical inactivation of cholinergic and adrenergic terminals of the intracardiac nervous system with liposomal neuromodulators increased the resistance to AF in an acute experiment. However, the short observation period does not allow making a definite conclusion about the role of the autonomic nervous system in the pathogenesis of AF, which requires verification of the obtained data in a chronic experiment.

Generation of Reactive Oxygen Species by Human Whole Blood Cells Exposed to Iron Oxide Magnetic Nanoparticles Coated with Different Shells.

We compared dose-dependent influence of magnetic nanoparticles (MNP) coated with different shells on ROS generation during incubation with whole human blood. ROS generation was evaluated using luminol dependent chemiluminescence. MNP with polylactide shell in concentrations of 0.2-2.0 mg/ml had no effect on spontaneous chemiluminescence, while MNP with polysaccharide shell induced a dose dependent enhanced spontaneous chemiluminescence that increased during incubation (1-3 h). MNP with albumin shell in concentrations of 0.2 mg/ml gradually enhanced spontaneous chemiluminescence during incubation, but increasing the concentration neutralized this effect.

Passive and active target delivery of drugs to ischemic myocardium.

Silica nanoparticles as carriers for targeted drug delivery to the heart were studied. Studies of hemodynamic parameters of rats after intravenous infusion of silica nanoparticles showed no acute toxicity. Intravenous infusion of silica nanoparticles to animals with ischemia-reperfusion of the myocardium led to accumulation of the nanoparticles in the focus of injury, which attests to possibility of passive targeted drug delivery to the myocardium.