title: Plasma purine nucleoside phosphorylase in cancer patients.
abstract: BACKGROUND
  Purine nucleoside phosphorylase (PNP) is the purine salvage enzyme that converts guanosine to guanine and inosine to hypoxanthine.
  
  
  METHODS
  279 samples from patients with differing cancers were collected during treatment at both pre- and post-dose stages for plasma PNP activity and compared with a normal population.
  
  
  RESULTS
  Normal plasma PNP activity was found to be 3.2+/-1.4 U/l (n=55) as compared with the cancer patients (pre-dose 12.3+/-7.4 U/l [n=215] and post-dose 11.2+/-5.9 U/l [n=64]). Levels of plasma PNP did not differ greatly between the different cancer types but were on average four times greater than that found in the reference population.
authors.affiliation: Biochemistry Department, Pathology Department, Bronglais Hospital, Aberystwyth, Ceredigion, SY23 1ER, UK. elton.roberts@ceredigion-tr.wales.nhs.uk
authors.forename: Elton L L
authors.initials: EL
authors.lastname: Roberts
authors.forename: Russell P
authors.initials: RP
authors.lastname: Newton
authors.forename: Alan T
authors.initials: AT
authors.lastname: Axford
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D016022:Case-Control Studies; D006801:Humans; D009369:Neoplasms / Q000097:blood / Q000201:enzymology*; D011683:Purine-Nucleoside Phosphorylase / Q000097:blood* / Q000187:drug effects* / Q000592:standards; D012016:Reference Values
chemical_list: D000970:Antineoplastic Agents; D011683:Purine-Nucleoside Phosphorylase