Chasing away accurate results: exhaustive chase protocols underestimate maximum metabolic rate estimates in European perch Perca fluviatilis.

Metabolic rates are one of many measures that are used to explain species' response to environmental change. Static respirometry is used to calculate the standard metabolic rate (SMR) of fish, and when combined with exhaustive chase protocols it can be used to measure maximum metabolic rate (MMR) and aerobic scope (AS) as well. While these methods have been tested in comparison to swim tunnels and chambers with circular currents, they have not been tested in comparison with a no-chase control. We used a repeated-measures design to compare estimates of SMR, MMR and AS in European perch Perca fluviatilis following three protocols: (a) a no-chase control; (b) a 3-min exhaustive chase; and (c) a 3-min exhaustive chase followed by 1-min air exposure. We found that, contrary to expectations, exhaustive chase protocols underestimate MMR and AS at 18°C, compared to the no-chase control. This suggests that metabolic rates of other species with similar locomotorty modes or lifestyles could be similarly underestimated using chase protocols. These underestimates have implications for studies examining metabolic performance and responses to climate change scenarios. To prevent underestimates, future experiments measuring metabolic rates should include a pilot with a no-chase control or, when appropriate, an adjusted methodology in which trials end with the exhaustive chase instead of beginning with it.

Clinical Durability of the CARMEDA BioActive Surface in EXCOR Ventricular Assist Device Pumps.

The durability of CBAS Heparin Surface on EXCOR pumps retrieved after clinical use for varying periods of time was studied by analyzing samples for surface heparin density and bioactivity. The mean time of clinical use of the investigated 14 EXCOR pumps was 178 days (range, 15-461 days). Mean heparin density was 3.1 ± 0.6 µg/cm² (range, 2.2-4.8 µg/cm²), and the measured mean heparin bioactivity was 14 ± 5 ρmol/cm² (range: 7-27 ρmol/cm²). There was no detectable degradation or loss of function of CBAS Heparin Surface over time. Samples from the housing and the membrane of the EXCOR pump showed no significant difference in heparin bioactivity or density. The CBAS Heparin Surface stays on the surface and remains bioactive on the EXCOR pump at least up until 1 year. This is an important demonstration of coating durability and supports the mid-term and long-term clinical use as bridge-to-heart transplantation or to myocardial recovery.