The present invention is directed to novel polypeptides having structural homology to IL-8 and to nucleic acid molecules encoding those polypeptides. The device may be used as a toy, and may be shaped like a play ball or as a handheld unit. The amplifier comprises a buffer amplifier that receives the differential input voltage and produces a differential input current. The data is analyzed to determine whether or not exercise has been performed. To provide the ambulatory patient with an added level of convenience and ease of use, such monitoring device is contained in a single integrated package. The tag receives the beacon signals and measures the signal strength of the beacon signals.