title: Evidence of age-dependent activity increase of poly(C)-avid-serum ribonuclease in man.
abstract: The activity of ribonuclease (E 3.1.4.22) was estimated in sera of 401 normal subjects (normal renal function, no signs of catabolism), age ranging from 16 to 100 years (mean: 50.25 +/- 19.98) with Poly (C) as substrate. Further activity was measured with the substrates Poly (U), Poly (A) and Poly (G) in 10 sera from each age decade between 21-30 years and 81-90 years. Greatest activity was found with Poly (C) as substrate (mean: 15.88 kU/l +/- 9.57). Covariant analysis (age as covariant) revealed no sex-related activity distribution at any age, whereas the age-dependent activity increase was highly significant (p less than 0.001; 11-20 years: 9.48 kU/l +/- 3.07; 81-90 years: 34.72 kU/l +/- 5.88). Activity with the other substrates was very low and constant throughout all ages. It seems to be mandatory to consider the age of the patient when interpreting ribonuclease activity.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011066:Poly C / Q000378:metabolism; D011119:Polynucleotides / Q000378:metabolism; D012260:Ribonucleases / Q000097:blood*; D012737:Sex Factors; D013379:Substrate Specificity
chemical_list: D011119:Polynucleotides; D011066:Poly C; D012260:Ribonucleases