ABSTRACT
Incubation of human serum samples with [adenine-14C]NAD resulted in a time- and dose-dependent incorporation of adenine moiety into CCI3COOH-precipitable material. Incorporated radioactivity was relatively resistant to neutral hydroxylamine, but was completely released by treatment with NaOH. An incorporation was observed also after preincubation of NAD with NAD glycohydrolase from pig brain. NAD glycohydrolase activity in serum samples was then shown spectroscopically in an assay coupled to alcohol oxidation. Thus, this reaction was implicated to be due to the binding of ADP-ribose, formed under the action of a soluble, endogenous NAD glycohydrolase activity, to serum proteins. Analysis by NaDodSO4/polyacrylamide gel electrophoresis (PAGE) and autoradiography indicated that a polypeptide of 97 kD, but also two further polypeptides of higher molecular weight and serum albumin, were labelled after incubation with radioactive NAD.
Subject(s)
Adenosine Diphosphate Ribose/metabolism , Blood Proteins/metabolism , NAD+ Nucleosidase/blood , NAD/blood , Animals , Blood Proteins/isolation & purification , Brain/enzymology , Carbon Radioisotopes , Humans , Hydrogen-Ion Concentration , Hydroxylamine , Hydroxylamines/pharmacology , Kinetics , NAD+ Nucleosidase/metabolism , Sodium Hydroxide/pharmacology , Swine , Time FactorsABSTRACT
Neurophysiological studies were conducted in 42 patients with classical phenylketonuria. The results of the intelligence quotient scores, electroencephalogram, visual evoked potentials and brain-stem auditory evoked potentials were evaluated. When compared with the controls, the subjects demonstrated a significant prolongation in VEP P1 and BAEP I-V interpeak latencies and an increase in VEP N1P1 amplitudes. No relationship was found between these pathological responses and metabolic control. However, the observation of normal intelligence quotient scores in 14 out of 18 patients who displayed a pathological prolongation in P1 latencies led us to the conclusion that evoked potentials may have a significant role in the determination of neurophysiological defects and that even cases with good metabolic control may have some obscure neurophysiological dysfunction which should be evaluated more carefully.
