Characterisation of the cellular mechanisms of effects of lidocaine, especially on ischaemia-reperfusion injured smooth muscle, may lead to improved treatment strategies for horses with POI.

No abstract

Objective: Despite the clinical success of large-diameter vascular grafts, synthetic grafts in small-diameter vessels are of limited use because of their poor patency rates. Previous experiments of our group provided evidence for good biocompatibility of bacterial nanocellulose (BNC) as a small-vessel graft in the carotid artery in sheep. However, the patency rate of our first-generation tubes after 3 months was only 50%. To advance our concept, we now used modified second-generation tubes with diminished wall thickness and a smoother inner surface to reduce the thrombogenic potential. The aim was to investigate mechanical characteristics of modified second-generation BNC tubes, to evaluate in vivo performance and biocompatibility, and to analyze patency rates.Methods: We replaced the right carotid artery of 23 sheep with second-generation BNC tubes. Compared with our firstgeneration tubes, tubes were modified with different surface properties and diminished wall thickness (inner diameter, 4.0-5.0 mm; wall thickness, 1.0-2.5 mm; length, 100 mm) to generate a smoother inner surface with reduced thrombogenic potential and a more porous outer zone, allowing easier cell immigration.Results: At the end of the investigational period, BNC tubes were explanted and grafts were processed for histopathologic analysis. Histologic analysis revealed no acute signs of foreign body reaction such as immigration of giant cells or other acute inflammatory reaction and therefore provided evidence for good biocompatibility of the second-generation tubes. However, all grafts of the sheep without antiplatelet therapy were occluded after 9 months, whereas grafts in sheep receiving dual platelet inhibition showed a patency rate of 67% (six of nine grafts). Further modified grafts revealed a patency rate of 80% (four of five grafts remained open).Conclusions: Patency rates of the second-generation tubes could be substantially improved compared with our firstgeneration tubes. However, poor patency rates of tissue-engineered blood vessels still limit their use in clinical studies. Further efforts in terms of in vitro and in vivo studies are essential to improve grafts of BNC.

Northern ungulates acclimatize to winter conditions with restricted food supply and unfavorable weather conditions by reducing energy expenditure and voluntary food intake. We investigated in a study on red deer whether rates of peptide and glucose transport in the small intestines are also reduced during winter as part of the thrifty phenotype of winter-acclimatized animals, or whether transport rates are increased during winter in order to exploit poor forage more efficiently. Our results support the latter hypothesis. We found in a feeding experiment that total energy intake was considerably lower during winter despite ad libitum feeding. Together with reduced food intake, mass of visceral organs was significantly lower and body fat reserves were used as metabolic fuel in addition to food. However, efficacy of nutrient absorption seemed to be increased simultaneously. Extraction of crude protein from forage was higher in winter animals, at any level of crude protein intake, as indicated by the lower concentration of crude protein in feces. In line with these in vivo results, Ussing chamber experiments revealed greater electrogenic responses to both peptides and glucose in the small intestines of winter-acclimatized animals, and peptide uptake into jejunal brush-border membrane vesicles was increased. We conclude that reduced appetite of red deer during winter avoids energy expenditure for unproductive search of scarcely available food and further renders the energetically costly maintenance of a large gut and visceral organs unnecessary. Nevertheless, extraction of nutrients from forage is more efficient in the winter to attenuate an inevitably negative energy balance.