Search PubMed⌕ Search

Biomedical subjects

A Belfield

Publications and source records attributed to A Belfield.

35 records · Page 2Linked to original sources
PubMed1971

Colorimetric determination of serum acid phosphatase activity using adenosine 3'-monophosphate as substrate.

The hydrolysis of adenosine 3'-monophosphate by serum acid phosphatase has been coupled to the liberation of ammonia from the adenosine generated through the action of exogenous adenosine deaminase. The ammonia is measured at the end of the incubation by a modification of the phenol-hypochlorite reaction of Berthelot. Optimum conditions for the enzyme reaction have been defined. Inhibition of the Berthelot reaction by the serum used in the assay is small, and may be compensated by a correction factor. Although the value for the control is high in relation to the test over the normal range, this is largely outweighed by the good sensitivity and precision of the method. The substrate is not significantly hydrolysed by erythrocyte acid phosphatase within the limits encountered in haemolysed sera. Experience of the method in routine hospital diagnosis compared favorably with that of a standard method employing disodium phenyl phosphate as substrate. It is suggested that activities greater than 3.1 IU/l should be further investigated and those greater than 3.7 IU/l should be regarded as definitely raised. The stability of human serum AcPase when promptly separated and held at 4 degrees C or - 20 degrees C was confirmed. At room temperature, acidification to pH 6.0 greatly improved stability.

Acid Phosphatase↗
PubMed1969

Activation of serum 5' nucleotidase by magnesium ions and its diagnostic applications.

Magnesium ions increase the hydrolysis of adenosine 5' monophosphate (5' AMP) by human serum at pH 7.9 but not at pH 9.3. The additional hydrolysis at pH 7.9 is predominantly due to increased activity of the specific phosphatase 5' nucleotidase (5Nase). This increase is proportional to enzyme concentration and has been employed as a measure of 5Nase activity in a sensitive micro-estimation. The normal range for serum 5Nase activity by this technique was 0 to 20 mIU/ml. In a series of over 200 patients, raised values were found frequently in hepatobiliary disease and infrequently in bone disease. Assay of 5Nase activity gave a more reliable indication of the source of raised serum alkaline phosphatase than isoenzyme electrophoresis in agar gel. The correlation between activities of the two enzymes was low in bone disease generally, and fairly good in hepatobiliary disease. The closest correlation was found in patients with parenchymal liver disease.

Adenine Nucleotides↗