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Purine nucleoside phosphorylase deficiency
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
PNP (see Figure 70.1) catalyzes the reversible conversion of inosine to hypoxanthine, guanosine to guanine, and also xanthosine to xanthine. Activity of the enzyme is readily assayed in erythrocytes, and patients have been reported to have no detectable activity [3]. The defect is also demonstrable in lymphocytes [12] and in granulocytes [4].
Quantifying RNA modifications by mass spectrometry: a novel source of biomarkers in oncology
Published in Critical Reviews in Clinical Laboratory Sciences, 2022
Amandine Amalric, Amandine Bastide, Aurore Attina, Armelle Choquet, Jerome Vialaret, Sylvain Lehmann, Alexandre David, Christophe Hirtz
In some cancer cohorts, non-modified nucleoside levels in urine are higher than in healthy control groups. For example, adenosine was elevated in lung cancer, colon/colorectal cancer [37,38] and breast cancer [39] patient urine. Cytidine was also increased in gastric [40], colon/colorectal [37,38] and breast [37,39] cancer samples. Guanosine was readily detected in the urine of patients with urogenital cancer [42]. Uridine was elevated in urogenital cancer [42] urine samples. One of the most abundant modified nucleosides, pseudouridine, which has its own symbol, ψ, and is referred to as the “fifth nucleoside”, was elevated in colorectal [38], urogenital [42], breast [39], ovarian [49], head and neck [46] cancer patient urine. Similarly, inosine, another common non-canonical nucleoside, was detected at high levels in the urine of patients with colorectal [38], breast [37,39] and urogenital cancer [42,43]. Following the same trend, xanthosine, which can result from distinct synthesis routes (including via inosine 5′-monophosphate or guanosine) was also present in higher concentrations in urine following breast [39], urogenital [42], head and neck [46] cancer development. Finally, the level of 1-methylinosine (m1I) rose in colorectal cancer [38] and bladder cancer [45].
Metabolomics markers in Neurology: current knowledge and future perspectives for therapeutic targeting
Published in Expert Review of Neurotherapeutics, 2020
Roberta Bonomo, Guido Cavaletti, Debra J. Skene
Concerning amino acid metabolism in AD patients, a reduction of branched-chain amino acids (BCAAs) [128,129], creatinine [129], and taurine [130] has been observed; while higher glutamate [130] and glutamine [131] levels were found. Interestingly, a metabolomics study on the entorhinal cortex has shown changes in the expression levels of deoxyguanosine, xanthosine and guanine in early stages of the disorder, followed by modifications in dGMP and glycine in advanced stages [132]. The observed regional differences in purine metabolism in AD cortex highlight the need for considering regional specificities as markers of regional vulnerability.
Repurposing existing drugs: identification of irreversible IMPDH inhibitors by high-throughput screening
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2019
Albertus Eka Yudistira Sarwono, Shinya Mitsuhashi, Mohammad Hazzaz Bin Kabir, Kengo Shigetomi, Tadashi Okada, Fumina Ohsaka, Satoko Otsuguro, Katsumi Maenaka, Makoto Igarashi, Kentaro Kato, Makoto Ubukata
Inosine 5′-monophosphate dehydrogenase (IMPDH) is an attractive drug target due to its essential role in cellular purine nucleotide biosynthesis. It catalyzes the conversion of IMP to xanthosine monophosphate (XMP), which will be eventually converted to guanosine monophosphate (GMP) for the DNA biosynthesis pathway.