insoluble nuclear fraction. Cytosine is the only target base of the methylase. The enzyme is species specific and appears to have different levels of activity in different organs of the same animal. Some of the properties of the mammalian deoxyribonucleic acid methylase are described.
There were no significant differences between the mean blood plasma (leu-kocyte-free) RNAuse activity among 128 healthy women volunteers age 13-70 and 49 women with benign gynecological tumors. Exceptions to this finding were three apparently healthy women volunteers who had plasma enzyme activity which was higher than two standard deviations from the mean of the control subjects. Increased plasma RNAase activity was also demonstrated for 21 of 22 patients with ovarian carcinomas of different histological types. This group included two patients with Stage IA, two patients with Stage IC ovarian carcinoma, and 17 patients with advanced ovarian carcinoma. The one exception was a patient with a well encapsulated, mucinous cystadenocarcinoma, Stage IA. The plasma RNAuse activity returned to normal values in all of the cancer patients who had no clinical evidence of residual malignant tissue after surgical treatment. However, the enzyme activity also returned to a normal value in one of the 17 women in whom all of the malignant tissue was not removed. These data indicate that plasma RNAase activity can be utilized as a tumor marker for the presence of ovarian malignancies of various histological types, and to differentiate between malignant and benign neoplasms.0 oratory is to establish a rapid and reliable method for the early diagnosis of ovarian cancer, ovarian cancer being the foremost problem in gynecological cancer we have today. In spite of the extensive use of surgery, radiotherapy and/or chemotherapy, the overall survival rate has remained approximately 30% over the past 30 years. g,21 The poor prognosis is largely attributable to the fact that at the time of diagnosis about 70% of ovarian cancers already have widespread intraperitoneal metastases. From these data it is evident that a practical method for the early diagnosis of ovarian cancer is essential. In order to achieve this goal, we elected to study the possibility of relating the presence of ovarian malignancies with the appearance of elevated blood serum or plasma ribonuclease (RNAase) activity. The rationale for this approach is based on the findings of other in-From the
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