No abstract

Preoperative PTH level cannot be used as a definite guide to the parathyroid adenoma's weight. Large parathyroid adenomas seem to secrete less PTH per unit weight than small adenomas. Calcium and phosphate do not seem to be of much value in predicting adenoma's weight in primary hyperparathyroidism.

Somatic cells do not have telomerase activity but immortalized cell lines and more than 85 % of the cancer cells show telomerase activation to prevent the telomere from progressive shortening. The activation of this enzyme has been found in a variety of human tumors and tumor-derived cell lines, but only few studies on telomerase activity in human brain tumors have been reported. Here, we evaluated telomerase activity in different grades of human astrocytoma and meningioma brain tumors. In this study, assay for telomerase activity performed on 50 eligible cases consisted of 26 meningioma, 24 astrocytoma according to the standard protocols. In the brain tissues, telomerase activity was positive in 39 (65 %) of 50 patients. One sample t test showed that the telomerase activity in meningioma and astrocytoma tumors was significantly positive entirely (P < 0.001). Also, grade I of meningioma and low grades of astrocytoma (grades I and II) significantly showed telomerase activity. According to our results, we suggest that activation of telomerase is an event that starts mostly at low grades of brain including meningioma and astrocytoma tumors.

Cyclin D2, P53, Rb and ATM as cell cycle genes regulate cell growth and proliferation. Considering their roles, we assumed that they have different level of mRNA expression in different grades of brain tumors. To determine this point, we investigated the mRNA expression in two types of brain tumors, including astrocytoma and meningioma. The mRNA of 52 brain tumor samples were extracted; cyclin D2, P53, Rb and ATM mRNA expression was quantified using the real-time quantitative reverse-transcription polymerase chain reaction. We compared mRNA expression of these genes between astrocytoma and meningioma tumors and also between different grades of them. Cyclin D2, P53, Rb and ATM had higher expression in astrocytoma than meningioma tumors. Higher grade (III and IV) of astrocytoma tumors had up-regulation for cyclin D2 and ATM genes, but higher grades of these tumors showed down-regulation of P53 and Rb genes. Analysis of relative expression between two grades of meningioma tumors showed a high down-regulation in grade II related to grade I. Also, cyclin D2, P53, Rb and ATM mRNA expression in each group of tumors (meningioma and astrocytoma) showed a highly positive correlation in lower grades. Considering this fact and also different templates of up- and down-regulation for these genes' interaction in different types of brain tumors, it seems that these genes do not have a unique model of interaction.