L. Lorenzini

Behavior of Enzymes Involved in Purine Nucleotide Metabolism in Tumors

Alterations in nucleotide metabolism have been observed in all experimental tumors. The “biosynthetic enzymes” and, specifically, phosphoribosylamidotransferase, which is the “key biosynthetic enzyme”, are clearly enhanced in experimental tumors, whereas “catabolic enzymes”-adenylate deaminase, S’-nucleotidase, purine nucleoside-phosphorylase and, specifically, xanthine oxidase (the “key catabolic enzyme”) — are decreased. The phosphoribosylamidotransferase/xanthine oxidase ratio increases with a characteristic pattern and is related to the aggressivity and invasiveness of the tumor1, 2.

Pattern of Methylated Purine Bases in Urine of Cancer Patients. Analysis by Mass Spectrometry

Methylated purine bases are constituents of both RNA and DNA. tRNA contains the highest number of such compounds. The methyl groups play different roles: they avoid “base pairing”, they allow codon identification, they recognize the enzyme aminoacyl tRNA synthetase, and they participate in the aminoacid transfer from tRNA to ribosomes1.

Radioimmunoassay of Folic Acid and its Correlation with Age

Folic acid is a very well known coenzyme that acts as carrier of monocarbon units and has a great importance in the synthesis of purine nucleotides. It occurs in vegetables as triand hepta-glutamate derivatives. The human body is absolutely unable to synthesize it.

Quality of life in advanced colorectal cancer

Colorectal carcinoma is a knowingly chemoresistant neoplasia. Fluorouracil (5-FU) is considered the standard drug for the treatment of advanced colorectal cancer and it is known that the action of 5-FU is potentiated by Folinic-acid (FA).