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  • Author: M Buchfelder x
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A Baur, M Buchfelder and J Kohrle

OBJECTIVE: Local 5'-deiodination of l-thyroxine (T(4)) to active thyroid hormone 3,3',5-tri-iodothyronine (T(3)) catalyzed by the two 5'-deiodinase enzymes (D1 and D2) regulates various T(3)-dependent functions in the anterior pituitary and has been well studied in rodents. Only limited information about deiodinase expression and its cellular distribution in human anterior pituitaries is available. DESIGN: We examined 5'-deiodinase enzyme activities in pituitary adenomas (18 non-functioning, seven TSH-producing, one GH- and TSH-producing, five GH-producing, eight prolactin (PRL)-producing, two adenomas each from patients with Cushing's disease and Nelson's syndrome) and three normal anterior pituitaries. METHODS: Activities were measured as release of (125)I(-) from tyrosyl-ring labeled reverse T(3) with or without propylthiouracil, a potent inhibitor of D1 which does not influence D2 activities. RESULTS: Most of the adenomas and normal tissues expressed both isoenzymes, with D2 activity higher than D1. In a few tissues D1 activity was higher than D2 and some tissues did not express D1 activity at all. Highest activities of both enzymes were found in TSH- and PRL-producing adenomas but absolute activities and the D1/D2 ratio were variable in the same kind of tumor in different patients. CONCLUSION: The finding that all examined tissues expressed 5'-deiodinase activity, most of them expressing both isoenzymes, implies that both enzymes are still active in tumors and that local deiodination is important for the function and feedback regulation of human anterior pituitary.

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M. Buchfelder, R. Fahlbusch, M. Walther and K. Mann

Abstract. The authors have investigated hypothalamicpituitary function in 8 patients (aged 9–27 years) with surgically and histologically proven suprasellar germinomas. Diabetes insipidus was found in 7 patients. All the patients had hypogonadism and hypocortisolism as judged by dynamic endocrine testing. Hypothyroidism was found in 6. Moreover, growth hormone secretion, as assessed by insulin-induced hypoglycemia, was defective in all patients. Comparison of results of insulin-induced hypoglycemia testing and stimulation tests by CRH and GHRH suggested that all patients had a primary supra-hypohypophyseal lesion rather than a primary pituitary defect. The authors conclude that suprasellar germinomas, although uncommon, should be included in the differential diagnosis of juvenile suprasellar tumours and in cases suggestive of idiopathic diabetes insipidus, even if neuroradiological investigation fails to demonstrate a discrete tumour.

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S. BROCKMEIER, U. SCHRELL, M. BUCHFELDER and R. FAHLBUSCH

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M. BUCHFELDER, B. BÖHM, U. SCHRELL, J. PICHL and R. FAHLBUSCH

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W. SCHOTT, M. BUCHFELDER, U. SCHRELL and R. FAHLBUSCH

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J. PICHL, U. SCHRELL, M. BUCHFELDER and R. FAHLBUSCH

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M. BUCHFELDER, S. BROCKMEIER, U. SCHRELL, J. PICHL and R. FAHLBUSCH

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C Dimopoulou, J Schopohl, W Rachinger, M Buchfelder, J Honegger, M Reincke and G K Stalla

Objective

Transsphenoidal surgery (TSS) presents the treatment of choice for Cushing's disease (CD). Remission and recurrence rates vary dependent on tumor size, extension, adenoma visibility on magnetic resonance imaging, and neurosurgical expertise. Other than published from single-surgeon neurosurgical series so far, we have aimed to describe long-term remission and recurrence rates of CD in a series incorporating different neurosurgeons, trying to reflect care reality in the Munich Metropolitan Region, which is accommodated by three tertiary university and multiple, smaller neurosurgical centers.

Design

We conducted a retrospective analysis of 120 patients who underwent first and 36 patients who underwent second TSS as treatment for CD between 1990 and 2012.

Methods

Patients were divided into three groups according to remission status. Potential risk factors for recurrence, pituitary function, and strategy in persistent disease were assessed.

Results

Three outcome groups were identified according to remission status after first TSS (mean follow-up 79 months): remission, 71% (85/120), disease persistence, 29% (35/120), and disease recurrence, 34% (29/85) (mean time to recurrence 54 months). After second TSS (n=36, mean follow-up 62 months), we documented remission in 42% (15/36), disease persistence in 58% (21/36), and disease recurrence in 40% (6/15) (mean time to recurrence 42 months). Postoperative hypocortisolism after first, though not after second, TSS was associated with a lower risk of suffering disease recurrence (risk=0.72; 95% CI 0.60–0.88; exact significance (two-sided) P=0.035).

Conclusions

Our study shows higher recurrence rates of CD after first TSS than previously reported. Second TSS leads an additional 8% of the patients to long-term CD remission.