The present invention relates to new antibiotic macrolide compounds of the general formula I:with improved activity, to medicaments comprising such antibiotics, and to the use of such antibiotics for the treatment of infectious diseases, inflammatory diseases and human diseases or disorders which can be ameliorated by inhibition human phospdiesterases. Sealed-mode operation is necessary when using the boron-coated straw detectors in the field, where access to a continuous flow of the required gas mixture is not practical. The shaft has a proximal end and a distal end.