Evaluation of a simple method for the measurement of cytidine deaminase in serum and comparison with a reference method

Serum adenosine deaminase and cytidine deaminase activities in patients with systemic lupus erythematosus

We evaluated serum total adenosine deaminase, its isoenzymes adenosine deaminase-1 and adenosine deaminase-2, and cytidine deaminase activities in 24 patients with active systemic lupus erythematosus, and in 26 healthy control subjects, and found the means +/- SD values to be 21.38 +/- 5.96 IU/l, 3.74 +/- 2.12 IU/l, 17.72 +/- 5.02 IU/l and 17.89 +/- 4.62 IU/l, respectively in the patients, and 14.97+/- 4.71 IU/l, 4.01 +/- 1.35 IU/l, 10.91 +/- 3.91 IU/l and 7.39 +/- 3.97 IU/l, respectively in the control subjects. When compared to the healthy controls, serum total adenosine deaminase, adenosine deaminase-2 and cytidine deaminase levels were significantly higher (p<0.001) in systemic lupus erythematosus patients, but the decrease of adenosine deaminase-1 level was not statistically significant (p>0.05). The increased adenosine deaminase-2 may be of macrophage origin. It closely correlated with clinical signs of active systemic lupus erythematosus. The membranes of polymorphonuclear neutrophils may be damaged, and cytidine deaminase may be released into serum. In conclusion, serum total adenosine deaminase, adenosine deaminase-2 and cytidine deaminase activities may serve as useful indicators for evaluating disease activity in patients with active systemic lupus erythematosus.

Activities of adenosine deaminase, 5'-nucleotidase, guanase, and cytidine deaminase enzymes in cancerous and non-cancerous human breast tissues

We measured activities of some DNA turnover enzymes in 9 breast tissues with stage II cancer, 6 breast tissues with stage IIIa cancer, and 9 non-cancerous adjacent breast tissues from the same patients with stage II cancer. We found higher Adenosine Deaminase (ADA) and 5'-Nucleotidase (5'NT) and lower Guanase (GUA) activities in the cancerous tissues compared with the non-cancerous ones. No meaningful differences were however found between Cytidine Deaminase (CD) activities. Regarding the correlation analysis, positive correlations were established between ADA and 5'NT activities of the cancerous tissues (r = 0.45 for the tissues with stage II and r = 0.60 for the tissues with stage IIIa cancer). No meaningful correlations were however found between other enzyme activities. Relating to activity ratios, no meaningful differences were found between ADA/5'NT values in the tissues. GUA/CD ratios were however lower and the other ratios higher in the cancerous tissues. Results indicated that ADA and 5'NT activities increased and GUA activity decreased in the cancerous breast tissues but CD activities did not change in the tissues affected. It has been suggested that increased ADA and 5'NT together with decreased GUA activities might be a physiologic attempt of the cancer cells to provide more substrates needed by cancer cells to accelerate the salvage pathway activity. Furthermore, high ADA activity might also play part in the detoxication process of high amounts of toxic adenosine and deoxyadenosine substrates produced from accelerated purine metabolism in the cancerous tissues.

Adenosine deaminase, 5'-nucleotidase, guanase and cytidine deaminase activities in gastric tissues from patients with gastric cancer

The activities of some of the enzymes participating in nucleotide metabolism were measured in cancerous and noncancerous gastric tissues from patients with gastric cancer. The enzyme activities measured were found to be higher in the cancerous tissues than in the non-cancerous tissues. Adenosine deaminase (ADA), 5'-nucleotidase (5'-NT), guanase (GUA) and cytidine deaminase (CD) activities in the cancerous tissues were 56.0 +/- 24.0, 45.0 +/- 20.0, 0.34 +/- 0.16 and 4.65 +/- 2.04, respectively. The activities in non-cancerous tissues were 13.2 +/- 6.0, 19.8 +/- 8.3, 0.12 +/- 0.06 and 1.65 +/- 0.8, respectively. Cancerous tissues consisted of 7 gastric tissues with Grade I-II and 8 tissues with Grade III-IV adeno cancer. Non-cancerous adjacent tissues were obtained from the same patients with Grade I-II cancer. There were no meaningful differences between enzyme activities of the gastric tissues with Grade I-II and Grade III-IV cancer. Enzyme activity ratios indicates that ADA activity increased by the highest amount relative to other enzyme activities in the cancerous tissues. In the correlation analysis, we found positive correlations between some of the enzyme activities in the cancerous tissues. Results suggest that increased activities of these enzymes might play a part in the accelerated nucleotide metabolism in the cancerous gastric tissues.

Cytidine deaminase activity in abnormal pregnancy

OBJECTIVE

To determine the usefulness of cytidine deaminase (CTD) activity in the prediction of abnormal pregnancy and the prognosis of fetal outcome.

METHOD

The CTD activities in 367 pregnant women and 17 placentas and their cord sera were determined. The CTD activity was estimated to determine the amount of ammonia liberated during conversion of cytidine into uridine. The Kruskal-Wallis test and paired t-test were employed for statistical comparisons.

RESULT

The placentas contained extremely high levels of CTD activity, but the cord serum did not. The mean value of CTD activity in abnormal pregnancy women was significantly higher than in normal pregnancy women. The two cases with a CTD activity of 40 U or more had the worst infant prognosis.

CONCLUSION

The CTD activity in abnormal pregnancies was excessively elevated due to a damaged placenta under progressive deterioration. This CTD assay was simple and had predictive value for the prognosis of an infant of an abnormal pregnancy.