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Background: Telomerase is a speci®c enzyme that appears to have a key role in cellular senescence and the progression of neoplastic tissue. High telomerase activity has been found in several cancers, but not in most normal and benign tissue. Little is known about the in¯uence of telomerase on the abnormal growth associated with hyperparathyroidism. Objective: To analyse telomerase activity in parathyroid tissue obtained from 29 patients undergoing surgery for primary hyperparathyroidism. Design: Tissue for telomerase activity measurements was collected from six hyperplastic, 20 adenomatous and 22 normal parathyroid glands. Methods: The highly sensitive PCR-based telomeric repeat ampli®cation protocol, TRAP, combined with ELISA, was used to detect telomerase activity in tissue extracts containing 3.0 mg protein.Result: Telomerase was not activated in any of the analysed tissue by 3 mg protein. Reassay of 12 samples containing 6.0 mg protein veri®ed these negative TRAP results. Conclusion: Our ®ndings indicate that telomerase is not a part of the mechanism promoting parathyroid proliferation and the underlying conditions remain to be determined.

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Parathyroid hormone (PTH) mRNA in original and transplanted human adenomatous parathyroid tissue and human serum intact PTH (S-iPTH) was measured in athymic mice at 4, 7, 14, and 28 days after transplantation. Parathyroid tissue was obtained during surgery for hyperparathyroidism and implanted subcutaneously. PTH mRNA detection was done with RT-PCR followed by membrane blot and hybridisation and S-iPTH was analysed using a human specific immunoradiometric method. At 4 days, PTH mRNA was 79.6+/-5.3% (mean+/-SE) of that in original tissue whereas S-iPTH was only 5.4 ng/l. At 28 days, PTH mRNA was significantly reduced to 60.7+/-4.1% whereas S-iPTH was increased to 192 ng/l. The reduced PTH mRNA expression in the transplants at 28 days may be explained by an inhibited DNA transcription. The presence of human S-iPTH in transplanted mice at 4 days may be due to cell disintegration and diffusion. The gradual increase in S-iPTH during the experimental period probably reflects increased transplant cell volume and improved graft revascularisation.

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