We analyzed pedicle bone from roe bucks that had died around antler casting or shortly before or during the rutting period. Pedicles obtained around antler casting were highly porous and showed signs of intense osteoclastic activity that had caused the formation of an abscission line. Following the detachment of the antler plus a portion of pedicle bone, osteoclastic activity in the pedicles continued for some time, and new bone was deposited onto the separation plane of the pedicle stump, leading to partial pedicle restoration. Pedicles obtained around the rutting period were compact structures. The newly formed, often very large secondary osteons, which had filled the resorption cavities, exhibited a lower mineral density than the persisting older bone. The middle zones of the lamellar infilling frequently showed hypomineralized lamellae and enlarged osteocyte lacunae. This indicates a deficiency in mineral elements during the formation of these zones that occurred along with peak antler mineralization. We suggest that growing antlers and compacting pedicles compete for mineral elements, with the rapidly growing antlers being the more effective sinks. The competition between the two simultaneously mineralizing structures is probably more severe in Capreolus capreolus than in other cervids. This is because roe bucks regrow their antlers during late autumn and winter, a period of limited food and associated mineral supply. The pedicle is a heavily remodeled bone structure with distinct seasonal variation in porosity. Pedicle remodeling differs in several aspects from the normal bone remodeling process in the mammalian skeleton.

Objective: We improved our SIMVENT, a simulator to materialize lung equations with user selected ventilatory mechanics parameters, capable of producing spontaneous breathing to test MV operation. SIMVENT evaluates ventilators as VUTs. We designed an assisted ventilation training software to operate SIMVENT.Method: SIMVENT includes a cylinder with a stepmotor powered piston, a cylinder mimicking residual volume, sensors for "alveolar" & "airway" pressures, a stepmotor compressed tubing to simulate variable airway resistance, a microcontroller and a computer interface. SIMVENT acts as a patient with programmed values of airway resistance and lung compliance. SIMVENT compares flow and pressure signals with those shown by the VUT. Spontaneous inspiration attempts are created by SIMVENT to test VUT: breathing pressure drops are selected (5 cmH2O e.g.) either at random or phase-locked to the respiratory cycle. A report is generated for each VUT. SIMVENT was designed with "User centered" methodology.Results: Four ventilators were tested. VUT tidal volume differed up to 15%, airway pressure was within 8% and respiratory frequency within 4% of SIMVENT values.Conclusions: SIMVENT proved to be useful to test and compare ventilators as to their ability to detect spontaneous breathing. For the first time ventilators can be fully evaluated prior to clinical use. SIMVENT may also be used to train physicians.

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