香川 力

Protein kinase A (PICA) regulatory subunit type I alpha (RI alpha) is a major regulatory subunit that functions as an inhibitor of PKA kinase activity. We have previously demonstrated that elevated RI alpha expression is associated with diffuse-to-nodular transformation of hyperplasia in parathyroid glands of renal hyperparathyroidism. The aim of the current study was to determine whether or not RI alpha expression is increased in adenomas of primary hyperparathyroidism (PHPT), because monoclonal proliferation has been demonstrated in both adenomas and nodular hyperplasia. Surgical specimens comprising 22 adenomas and 11 normal glands, obtained from 22 patients with PHPT, were analyzed. Western blot and immunohistochemical analyses were employed to evaluate RI alpha expression. PKA activities were determined in several adenomas highly expressing RI alpha. RI alpha expression was also separately evaluated in chief and oxyphilic cells using the "Allred score" system. Expression of proliferating cell nuclear antigen (PCNA), a proliferation marker, was also immunohistochemically examined. Western blot analysis revealed that 5 out of 8 adenomas highly expressed RI alpha, compared with normal glands. PKA activity in adenomas was significantly less than in normal glands. Immunohistochemical analysis further demonstrated high expression of RI alpha in 20 out of 22 adenomas. In adenomas, the greater RI alpha expression and more PCNA positive cells were observed in both chief and oxyphilic cells. The present study suggested that high RI alpha expression could contribute to monoclonal proliferation of parathyroid cells by impairing the cAMP/PKA signaling pathway.

There are no current guidelines for the management of familial pheochromocytoma (FP). We tried to determine the optimal management of patients with FP. Among 191 patients with pheochromocytoma who underwent surgical resection between 1979 and 2010, there were 18 FP (13 different kindreds 11 females/7 males mean age at initial operation: 38.7 years). The 18 FP cases comprised 10 with MEN2A, 2 with MEN2B, 4 with von Hippel-Lindau disease, and 2 with FP only, and all pheochromocytomas were of adrenal origin. The number of probands and family members was 9 and 9 respectively. Mean tumor size was 6.4 cm in diameter. Simultaneous bilateral adrenalectomy was performed in 6 patients, and unilateral adrenalectomy was performed as the initial surgery in 12 patients. A metachronous contralateral adrenalectomy was performed in 3 patients, 90, 236 and 312 months after the primary operation, respectively. None of the patients received partial adrenalectomy. Among another 9 patients with unilateral adrenalectomy, contralateral pheochromocytomas were suspected in 4 cases at the initial operation. However, none of these contralateral lesions developed severe symptoms or tumor enlargement during a median follow-up of 116 months. In the remaining 5 patients, pheochromocytoma did not develop in the contralateral adrenals over a median follow-up of 80.5 months. Bilateral lesions of adrenal pheochromocytoma in familial cases occurred in 78% of cases (14/18) 9 patients (including 4 with contralateral pheochromocytoma) did not require a contralateral adrenalectomy during a median follow-up of 119 months. No patients have suffered from Addisonian crisis. The ipsilateral adrenalectomy and follow-up of contralateral small pheochromocytoma is one of the management options to preserve adrenocortical function in FP patients. © Jaypee Brothers Medical Publishers (P) Ltd.