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Summary.Anagrelide, an inhibitor of platelet aggregation, decreases the number of platelets in normal subjects and in patients with myeloproliferative disorders. We describe studies aimed at discovering the general mechanism(s) by which anagrelide acts. We examined three hypotheses:(1) anagrelide shortens platelet survival, (2) anagrelide inhibits the proliferation of megakaryocytic-committed progenitor cells (CFU-M), and (3) anagrelide inhibits maturation of megakaryocytes. We observed that anagrelide did not shorten platelet survival. Proliferation of CFU-M in vivo was not affected by anagrelide, although high concentrations of anagrelide inhibited CFU-M in vitro. In-vivo and in-vitro anagrelide altered the maturation of megakaryocytes, causing a decrease in their size and changing other morphometric features. We conclude that anagrelide decreases the number of platelets primarily by interfering with the maturation of megakaryocytes.

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Acromegaly often involves the presence of different pathologies of the thyroid gland. Long-lasting stimulation of the follicular epithelium by growth hormone (GH) and insulin-like growth factor 1 (IGF-1) can cause disorders in thyroid function, an increase in its mass and the development of goitre. Acromegalic patients present most frequently with non-toxic multinodular goitre. Nodules are more prevalent in patients with active acromegaly. It has been suggested that then thyroid size increases and it can be reduced through treatment with somatostatin analogues. The relationship between thyroid volume and the level of IGF-1 and the duration of the disease is unclear. Each acromegalic patient requires a hormonal and imaging evaluation of the thyroid when the diagnosis is made, and an accurate evaluation during further observation and treatment. Although the data concerning the co-occurrence of acromegaly and thyroid cancer still remain controversial, it is particularly important to diagnose the patient early and to rule out thyroid cancer.

Introduction. Invasive tumours in Nelson's syndrome need aggressive therapy. Recent reports have documented the efficacy of temozolomide (TMZ) in the treatment of adenomas resistant to conventional management. Objective. The review of the literature concerning TMZ treatment of atypical corticotroph adenomas and a case study of 56-year-old woman who developed Nelson's syndrome. Treatment Proceeding. The patient with Cushing's disease underwent transsphenoidal adenomectomy followed by a 27-month-long period of remission. Due to a regrowth of the tumor, she underwent two reoperations followed by stereotactic radiotherapy. Because of treatment failures, bilateral adrenalectomy was performed. Then she developed Nelson's syndrome. A fourth transsphenoidal adenomectomy was performed, but there was a rapid recurrence. Five months later, she underwent a right frontotemporal craniotomy. Due to a rapid regrowth of the tumour, the patient did not receive gamma-knife therapy and was treated with cabergoline and somatostatin analogue for some time. Only TMZ therapy resulted in marked clinical, biochemical, and radiological improvement. To date, this is the first case of invasive corticotroph adenoma in Nelson's syndrome treated with temozolomide in Poland. Conclusion. In our opinion, temozolomide can be an effective treatment option of invasive adenomas in Nelson's syndrome.