No abstract

Acetylcholinesterase (AChE) activities in different brain parts were determined quantitatively in rats treated with huperzine A, soman, and huperzine A followed by soman, using histochemical and biochemical methods. Following soman intoxication (1.2 x LD 50 , i.m.), AChE activity was decreased to 30-80% of control values depending on the brain structure. The most sensitive area was the frontal cortex and the most relatively resistant was ncl. ruber. Huperzine A treatment only caused a change in AChE activity varying from 70 to 100 % of control values. In rats pretreated with huperzine A and intoxicated with soman, AChE activity was significantly higher than that observed after soman. In these animals, survival of rats pretreated with huperzine was observed while the mortality of unpretreated animals was near to 80 %. The results suggest that huperzine A is good candidate for further study for clinical use as a prophylactic drug against nerve agent poisoning.Int. J. Mol. Sci. 2007, 8 1166

BackgroundThe aim of our experimental work was to assess morphological changes of arterial wall that arise during different thawing protocols of a cryopreserved human aortic root allograft (CHARA) arterial wall.MethodsThe experiment was performed on CHARAs. Two thawing protocols were tested: 1, CHARAs were thawed at a room temperature at +23°C; 2, CHARAs were placed directly into a water bath at +37°C.Microscopic samples preparationAfter fixation, all samples were washed in distilled water for 5 min, and dehydrated in a graded ethanol series (70, 85, 95, and 100%) for 5 min at each level. The tissue samples were then immersed in 100% hexamethyldisilazane for 10 minutes and air dried in an exhaust hood at room temperature. Processed samples were mounted on stainless steel stubs, coated with gold.ResultsThawing protocol 1: All 6 (100%) samples showed loss of the endothelium and damage to the subendothelial layers with randomly dispersed circular defects and micro-fractures without smooth muscle cells contractions in the tunica media.Thawing protocol 2: All 6 (100%) samples showed loss of endothelium from the luminal surface, longitudinal corrugations in the direction of blood flow caused by smooth muscle cells contractions in the tunica media with frequent fractures in the subendothelial layerConclusionAll the samples thawed at the room temperature showed smaller structural damage to the CHARA arterial wall with no smooth muscle cell contraction in tunica media when compared to the samples thawed in a water bath.

SEM (using HMDS drying) together with other methods may be helpful for the morphological control of processing, cryopreservation and liquid nitrogen storage of AHV. Severe AHV leaflet endothelial destruction was proven on AHV grafts. These changes arose already in the initial steps of tissue processing, just after the donor heart harvesting and then at the time of antibiotic valve graft treatment. These results are considered as the starting point for the development of a better preservation protocol.