Abstract: A compound of formula I ##STR1## wherein R is H or R'CO wherein R'CO is an acyl radical of a carboxylic acid,Y.sub.1 is the radical linked to an alpha carbon atom an .alpha.-amino acid,Y.sub.2 is the radical linked to an alpha carbon atom of an .alpha.-amino acid, ##STR2## --CH.sub.2 --S--S--CH.sub.2 --CH.sub.2 --COOH, --(CH.sub.2).sub.p --COOH or --CH.sub.2 --S--Y.sub.3,Y.sub.3 is (C.sub.1-4)alkyl or benzyl optionally substituted by methyl or methoxy,or CH.sub.3 CO--NH--CH.sub.2 --,n is 1 to 4,A.sub.6 is Thr or D-Thr,p is 3 to 5,A.sub.8 is the aminoacyl radical of a neutral, lipophilic L-.alpha.-aminoacid,A.sub.9 is the aminoacyl radical of a neutral, lipophilic L- or D-.alpha.-aminoacid,Z is a polypeptide radical corresponding to the polypeptide radical in positions 10 to 31 of a natural calcitonin or a derivative or analogue thereof having a hypocalcemic effect,wherein, when there is more than one Y.sub.1 radical, these are the same or different, and with the exception of radical A.sub.

Abstract: A combined smoke and gas detector utilizes a conventional smoke detector IC (44) which is operable to drive a piezo element (46) and an LED (94) to provide indication of a smoke or gas detection. An ionization chamber (58) is operable to detect smoke and a gas detector (98) is operable to detect gas. A comparator (104) detects the output of the gas detector (98) for input to the logic circuitry of the IC (44). The LED (94) is modulated to provide a distinction between gas detection and smoke detection in addition to the tone output from the piezo element (46).