Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.4.2.8 (hypoxanthine-guanine phosphoribosyltransferase)
 2,527 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The activity of inosine monophosphate dehydrogenase (IMPDH: EC 1.2.1.14) was measured in erythrocyte lysates using a non-radiolabelled method linked to reversed-phase liquid chromatography (RPLC). The mean activity in erythrocytes from healthy controls using this sensitive method was extremely low (mean 85 pmol/h per mg protein, range 4-183). The elevated erythrocyte IMPDH activity reported previously in hypoxanthine-guanine phosphoribosyltransferase (HPRT) deficiency was confirmed (mean 234 pmol/h per mg protein). Erythrocyte IMPDH activity of patients with other disorders of purine metabolism, or with leukaemias and lymphomas, showed no marked difference from controls, except in one instance--an immunodeficient child with purine nucleoside phosphorylase (PNP) deficiency, treated with Ribavirin, where a 30-fold increase in activity was found (2670 pmol/h per mg protein). Investigation of erythrocyte IMPDH in other immunodeficient children with normal PNP activity demonstrated that this grossly elevated erythrocyte activity was attributable to induction of IMPDH by Ribavirin therapy.
 ...
PMID:Demonstration of induction of erythrocyte inosine monophosphate dehydrogenase activity in Ribavirin-treated patients using a high performance liquid chromatography linked method. 758 76

Chromosomal aberrations in human gliomas are principally numerical. In tumours of low malignancy, karyotypes are frequently normal, but occasionally an excess of chromosome 7 and a loss of sex chromosome are observed. In highly malignant tumours, the most frequent aberrations are gain of chromosome 7, loss of chromosome 10 and less frequently losses or deletions of chromosomes 9, 22, 6, 13 and 14 or gains of chromosomes 19 and 20. To understand the meaning of these chromosome imbalances, the relationships between chromosome abnormalities and metabolic disturbances were studied. The losses or deletions observed affected principally chromosomes carrying genes encoding enzymes involved in purine metabolism. The activities of ten enzymes were measured: adenosine kinase, adenine phosphoribosyltransferase, adenylate kinase, methylthioadenosine phosphorylase, hypoxanthine phosphoribosyltransferase, adenylosuccinate lyase, inosine monophosphate dehydrogenase, adenosine deaminase, nucleoside phosphorylase and adenosine monophosphate deaminase. In parallel, two enzymes involved in pyrimidine metabolism, thymidine kinase and thymidylate synthase (TS), were studied. The activities of all these enzymes were measured on samples from 30 human primary glial tumours with low or high malignancy, six xenografted tumours at different passages, four portions of normal brain tissue and four non-glial brain neoplasms. As suggested by cytogenetic data, the enzymatic results showed a relatively low activity of purine metabolism in glial tumours when compared with normal brain and non-glial brain neoplasms. Considering the two enzymes involved in pyrimidine metabolism, only TS had higher activity in glial tumours of high malignancy than in normal brain. In comparison with normal brain, the balance between salvage and de novo pathways changes in gliomas, and even more in grafted tumours, in favour of de novo synthesis. The relation between chromosomes and metabolic imbalances does not correspond to a simple gene dosage effect in these tumours. These data suggest that the decrease of adenosine metabolism occurs before chromosomal aberrations appear, since it is observed in tumours of low malignancy when most karyotypes are still normal, and that the de novo pathway increases with tumour progression.
 ...
PMID:Purine and pyrimidine metabolism in human gliomas: relation to chromosomal aberrations. 805 68

Thiopurines are widely used in the treatment of inflammatory bowel disease (IBD). However, in clinical practice azathioprine (AZA) or 6-mercaptopurine (6-MP) are not effective in one-third of patients and up to one-fifth of patients discontinue thiopurine therapy due to adverse reactions. The observed interindividual differences in therapeutic response and toxicity to thiopurines are explained to a large extent by the variable formation of active metabolites, which is at least partly caused by genetic polymorphisms of the genes encoding crucial enzymes in thiopurine metabolism. In this in-depth review we discuss the genetic polymorphisms of genes encoding for glutathione S-tranferases, xanthine oxidase, thiopurine S-methyltransferase, inosine triphosphate pyrophosphatase, hypoxanthine phosphoribosyltransferase, inosine monophosphate dehydrogenase and multidrug resistance proteins. Pharmacogenetic knowledge in this field has increased dramatically and is still rapidly increasing, but the translation into practical guidelines with tailored advices will cost much effort in the near future.
 ...
PMID:Pharmacogenetics of thiopurines in inflammatory bowel disease. 2020 60