OBJECTIVE: The selenoenzyme type 2 iodothyronine 5' deiodinase (DII) catalyzes the conversion of thyroxine into its active form tri-iodothyronine (T3), modulating thyroid hormone homeostasis in a local, tissue-specific manner. The amphibian, rodent and human cDNAs encoding this enzyme have been recently cloned and expressed. At present, little information regarding the genomic structure of mammalian DII is available. DESIGN AND METHODS: The complete structure, including intron-exon junctions, of the human DII (hDII) gene was obtained by long PCR and rapid amplification of cDNA ends (RACE). Chromosomal assignment of the hDII gene was performed by fluorescence in situ hybridization using a highly specific probe. RESULTS AND CONCLUSIONS: Our data demonstrated that hDII is a single copy gene located on chromosome 14, position 14q24.3. The gene spans over 15 kb, and the 7 kb transcript is encoded by three exons of 149 bp, 273 bp and 6.6 kb separated respectively by two 274 bp and 7.4 kb introns. A restriction map of the hDII gene is also reported. These data will help in further studies of the role of DII in the maintenance of peripheral thyroid hormone homeostasis.

Color Doppler gives us the possibility to study autonomous thyroid nodules and their qualitative and morphological aspects and allows us to hit session by session the most vascular area of the nodule with alcohol (Percutaneous ethanol injection). The use of color gives an easier flowmeter analysis reducing its time of performance. Today this method with the latest up to date echographs can provide very good clinical pathology at relatively low costs. We studied 18 patients, with autonomous thyroid nodules. They were all treated by percutaneous echo-guided ethanol injection (PEI). Before the beginning we make sure that the rest of the thyroid gland may function normally. The color Doppler test was carried out by using the multidisciplinary ecotomograph AU 560 CFM supplied with a linear probe 7.5 mHz, AL 35 by Esaote Biomedica. Before the PEI treatment, with the eco color Doppler test we noticed that the hot nodules clearly presented a higher vascularization compared to the remaining parenchyma. The vascularization was more evident in the peripheral area of the nodule even if few signs of flow were present inside the nodule. During a 24 months followup, 10 patients showed an important reduction and sometimes even the extinction of the intranodular flow signs followed by a clear reduction of the nodule's volume.

Autonomously functioning thyroid nodule (AFTN) includes a wide spectrum of unique or multifocal diseases, either hyper or euthyroid, which share the same independence from thyroid stimulating hormone (TSH) regulation in terms of growth and function. The pathological basis and the recent molecular implications of the disease are briefly discussed. Clinical and epidemiologic data of 1572 patients with AFTN, out of a population of 14107 patients with thyroid diseases, sequentially evaluated from 1974 to 1992, have been retrospectively examined. The mean age of AFTN occurrence is 41 years and it appears more frequently in women (F/M = 5.3/1). Clinical hyperthyroidism occurs only in 17% of patients and is more frequently observed in men over 40 years of age. The presence of sonolucent area inside the nodule is detectable in 8.6% of cases and may be associated with spontaneous arrest of growth. When AFTN is submitted to cytologic evaluation, patterns similar to those observed in nodular goiter are shown (colloid lesion, cyst and nodular hyperplasia). Signs of hyperactivity are also shown by follicular cells. In the presence of a cyst, a fine needle aspiration was performed and a complete resolution was observed in 40% of cases. When cyst recurred after aspiration, a solution of tetracycline was inserted into the cavity. Sclerosing therapy was efficient in evacuating the volume of the nodule in 50% of the cases. Patients with AFTN were followed for a mean period of 61 months and 84.7% of them did not show any morphological or functional change, while the remaining 15.3% of cases became hyperthyroid.(ABSTRACT TRUNCATED AT 250 WORDS)