Abstract: Digital calibration of an A/D converter, which converts an analog signal into a digital signal, is performed by first sequentially inputting two analog signals of different values to the A/D converter, then calculating an offset calibration value and gain calibration coefficient on the basis of two digital converted signals generated from the A/D converter and then calibrating a digital signal output from the A/D converter on the basis of the thus-calculated offset calibration value and gain calibration coefficient.

Abstract: Vitamin B.sub.12 compounds, salts and pharmaceutical compositions containing said compounds represented by formula (I): ##STR1## wherein L, a ligand to the cobalt of the corrin ring, is selected from the group consisting of a cyano or adenosyl group, B is an imidazole group or a 5,6-dimethylbenzimidazole group, and R is a straight alkylene group having 1 to 8 carbon atoms, are disclosed. Methods for preparing compounds of Formula (I) as well as methods for using the compounds in in vitro assays, in cell growth studies and in in vivo studies using transplanted murine tumor cells are disclosed.