In patients with lifetime isolated GHD, 6-month treatment with GH has reversible beneficial effects on body composition and metabolic profile, but it causes a progressive increase in intima-media thickness and in the number of atherosclerotic carotid plaques.

To study the doses received by patient submitted to ionizing radiation, several materials are used to simulate the human tissue and organs. The total mass attenuation coefficient is a reasonable way for evaluating the usage in dosimetry of these materials. The total mass attenuation coefficient is determined by photon energy and constituent elements of the material. Currently, the human phantoms are composed by a unique material that presents characteristics similar to the mean proprieties of the different tissues within the region. Therefore, the phantoms are usually homogeneous and filled with a material similar to soft tissue. We studied ten materials used as soft tissue-simulating. These materials were named: bolus, nylon ® , orange articulation wax, red articulation wax, PMMA, modelling clay, bee wax, paraffin 1, paraffin 2 and pitch. The objective of this study was to verify the best material to simulate the human cerebral tissue. We determined the elementary composition, mass density and, therefore, calculated the total mass attenuation coefficient of each material. The results were compared to the values established by the International Commission on Radiation Units and Measurements -ICRU, report n° 44, and by the International Commission on Radiation Protection -ICRP, report n° 89, to determine the best material for this energy interval. These results indicate that new head phantoms can be constructed with nylon ® .

Objective: GH replacement therapy (GHRT) in adult-onset GH deficiency (AOGHD) reduces carotid intima-media thickness (IMT) and increases myocardial mass, with improvement of systolic and diastolic function. These observations have reinforced the use of GHRT on AOGHD. Conversely, we have previously reported that in adults with lifetime congenital and severe isolated GH deficiency (IGHD) due to a mutation in GHRH receptor gene (GHRHR), a 6-month treatment with depot GH increased carotid IMT, caused the development of atherosclerotic plaques, and an increase in left ventricular mass index (LVMI), posterior wall, and septal thickness and ejection fraction. Such effects persisted 12 months after treatment (12-month washout -12mo). Methods: We have studied the cardiovascular status (by echocardiography and carotid ultrasonography) of these subjects 60 months after completion of therapy (60-month washout -60mo). Results: Carotid IMT reduced significantly from 12 to 60mo, returning to baseline (pre-therapy) value. The number of individuals with plaques was similar at 12 and 60mo, remaining higher than pretherapy. LVMI, relative posterior wall thickness, and septum thickness did not change between 12 and 60mo, but absolute posterior wall increased from 12 to 60mo. Systolic function, evaluated by ejection fraction and shortening fraction, was reduced at 60mo in comparison with 12mo returning to baseline levels. The E/A wave ratio (expression of diastolic function) decreased at 60mo compared with both 12mo and baseline. Conclusions: In adults with lifetime congenital IGHD, the increase in carotid IMT elicited by GHRT was transitory and returned to baseline 5 years after therapy discontinuation. Despite this, the number of subjects with plaques remained stable at 60mo and higher than at baseline. 166 977-982 European Journal of Endocrinology

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