Urinary excretion of modified nucleosides as biological marker of RNA turnover in patients with cancer and AIDS.

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.

Estimation of whole-body RNA catabolism based on the urinary modified nucleoside levels of cancer and AIDS patients.

From the relationship between the molar ratio of nucleosides calculated stoichiometrically from modified nucleoside occurrences in major RNA species and the proportion of rRNA to all of RNA contents in average tissues, the increase of rRNA contents in cancer tissues growing rapidly was found. Thus, we found that selected urinary modified nucleoside levels were very useful as a biological marker of cancer and AIDS, as well as a good indicator of whole-body metabolic conditions of RNAs.

Analysis, identification and determination of urinary modified nucleosides of cancer and AIDS patients.

Modified nucleoside levels in urine samples collected before and after surgery from seven patients with malignant gastrointestinal cancer were examined by the reversed-phase HPLC method. Those of an AIDS patient, a breast cancer patient, and pooled normal urines were also compared. To monitor the effects of therapy on cancer patients, the levels of modified nucleosides, especially t6A and MTA, were found to be fairly effective.

Low nanogram detection of nucleotides using fast atom bombardment-mass spectrometry.

The effect of trimethylsilyl (TMS) derivatization on detection limits of mononucleotides in fast atom bombardment-mass spectrometry (FAB-MS) was examined. FAB-MS methods were developed to optimize sensitivity using adenosine 5'-monophosphate as a model compound and then applied to reference standards of two clinically important nucleotides: tricyclic nucleoside-5'-monophosphate (TCNMP) and 5-fluoro-2'-deoxyuridine-5'-monophosphate (FdUMP). The detection limit for the TMS derivative of TCNMP was 2.

Thermal stability of prehospital medications.

To evaluate the effect of prolonged environmental extremes on common prehospital medications, four identical sets of 23 drugs were placed in a simulated environment for up to four weeks. Subsequently, the samples were analyzed by gas chromatography-mass spectrometry for evidence of degradation byproducts. Twenty-one of the 23 samples showed no breakdown products; however, isoproterenol demonstrated 11% loss of parent compound after four weeks of environmental exposure.