Median sternotomy approach for chronic bovine experiments

Pain assessment in animal models: do we need further studies?

In the last two decades, animal models have become important tools in understanding and treating pain, and in predicting analgesic efficacy. Although rodent models retain a dominant role in the study of pain mechanisms, large animal models may predict human biology and pharmacology in certain pain conditions more accurately. Taking into consideration the anatomical and physiological characteristics common to man and pigs (median body size, digestive apparatus, number, size, distribution and communication of vessels in dermal skin, epidermal-dermal junctions, the immunoreactivity of peptide nerve fibers, distribution of nociceptive and non-nociceptive fiber classes, and changes in axonal excitability), swines seem to provide the most suitable animal model for pain assessment. Locomotor function, clinical signs, and measurements (respiratory rate, heart rate, blood pressure, temperature, electromyography), behavior (bright/quiet, alert, responsive, depressed, unresponsive), plasma concentration of substance P and cortisol, vocalization, lameness, and axon reflex vasodilatation by laser Doppler imaging have been used to assess pain, but none of these evaluations have proved entirely satisfactory. It is necessary to identify new methods for evaluating pain in large animals (particularly pigs), because of their similarities to humans. This could lead to improved assessment of pain and improved analgesic treatment for both humans and laboratory animals.

Development of DexAide right ventricular assist device: update II

The DexAide right ventricular assist device (RVAD) is a magnetically and hydrodynamically levitated implantable centrifugal pump. Recent progress includes 1) redesign of the inflow/outflow conduits, which yielded two successful 3-month experiments, 2) development of alternative journal bearing materials, and 3) completion of an 18-month duration of in vitro endurance testing. Verification testing of the RVAD electronics has been completed, and a prototype biventricular assist device (BVAD) system has been tested. Acute DexAide/CorAide BVAD implantations via median sternotomy in two calves documented BVAD control algorithms and anatomical fit. A drug-induced chronic calf heart failure model, currently under development in our laboratory, resulted in a successful BVAD implantation in a calf with heart failure. Our future plans are to complete in vitro and in vivo validation of alternative bearing materials, perform preclinical DexAide in vivo and in vitro reliability studies, and obtain Food and Drug Administration (FDA) approval for an Investigational Device Exemption to conduct a clinical pilot study. In conclusion, two successful 3 month in vivo experiments and an 18-month in vitro endurance test were completed. After final bearing material selection, the DexAide design will be "frozen" so that preclinical systems can be manufactured. BVAD experiments using a chronic heart failure model are in progress.