Using boronate gel affinity chromatography and reversed-phase high-performance liquid chromatography (RP-HPLC), a method for the simultaneous determination of 12 urinary modified
nucleosides has been developed. The RP-HPLC fractions were identified by gas chromatography/mass spectrometry analysis. The HPLC quantitation of urinary
nucleoside levels before and after surgery of
cancer patients suggested that urinary
5'-deoxy-5'-methylthioadenosine and N-[(9-beta-D-ribofuranosyl-9H-
purine-6-yl) carbamoyl]-
L-threonine (t6A) levels were helpful in monitoring
therapeutic effects in
cancer patients. From the fact that molar ratios of urinary
N2,N2-dimethylguanosine (m2 2G)
pseudouridine (psi) and t6A/psi in
cancer patients were lower than those of normal or post-surgical
cancer patients, the increase of rRNA content in
cancer tissues growing rapidly was estimated using the stoichiometric relationship between the ratio of the number of residues of their modified
nucleoside in RNAs and the proportion of rRNA to total RNAs in average tissues of whole body. Furthermore, from the estimation of
RNA turnover using urinary
nucleoside levels, it was found that the half-lives of rRNA rather than
tRNA of patients with
cancer and those of both RNAs in the case of
acquired immunodeficiency syndrome (
AIDS) were extremely short compared with those of the normal. Thus, we discovered that the selected urinary modified
nucleosides were very useful as a
biological marker of whole-body
RNA turnover in patients with
cancer and
AIDS.