Low Young's modulus Ti-based porous bulk glassy alloy without cytotoxic elements.

UNLABELLED: A new a biocompatible Ti42Zr40Ta3Si15 (atomic %) porous bulk glassy alloy was produced by combination of rapid solidification and powder metallurgy techniques. Amorphous alloy ribbons were fabricated by melt spinning, i.e. extremely fast quenching the molten alloy with 10(6)K/s from T=1973K down to room temperature. The ribbons were then cryo-milled at liquid nitrogen temperature in order to produce powder, which was subsequently hot pressed. The resulting thick pellets have a porosity of about 14vol%, a high compression strength of 337MPa and a Young's modulus of about E=52GPa, values very close to those characteristic of cortical bone. Moreover, the morphology of the samples is very similar to that of cortical bone. The biocompatibility, which is due to the absence of any toxic element in the chemical composition, together with the suitable mechanical behavior, make these samples promising for orthopedic and dentistry applications. STATEMENT OF SIGNIFICANCE: Ti-based alloys are nowadays the standard solution for biomedical implants. However, both the conventional crystalline and amorphous alloys have higher rigidity as the human bone, leading to the damage of the bone at the interface, and contains harmful elements like vanadium, aluminum, nickel or beryllium. The hierarchical porous structures based on glassy alloys with biocompatible elements is a much better alternative. This work presents for the first time the manufacturing of such porous bodies starting from Ti-based amorphous alloy ribbons, which contains only non-harmful elements. The morphology and the compressive mechanical properties of these new products are analyzed in regard with those characteristic to the cortical bone.

SELENIUM STATUS IN AUTOIMMUNE THYROIDITIS.

UNLABELLED: Selenium (Se) is an important element that exerts its effects through selenoproteins. The thyroid gland has the highest Se concentration and specific selenoprotein enzymes families are crucial in the thyroid hormone metabolism. There is little evidence on the link between Se and thyroid autoimmune disease, therefore future studies are required to elucidate the nature of this associ ation. AIM: To evaluate the Se status in euthyroid subjects with autoimmune thyroiditis. MATERIAL AND METHODS: From January 2014 to January 2015 we recruited 100 consecutive euthyroid subjects with autoimmune thyroiditis, living in the same region and with normal iodine intake. Serum concentrations of Se, thyroid antibodies (antithyroperoxidase--TPOAb--and antithyroglobulin--TgAb), thyroid-stimulating hormone (TSH), and thyroid ultrasound were performed in all patients. RESULTS: Mean age of the study group was 48.87 ± 12.83 years, range: 18-82 years. Since thyroid pathology is more frequent in the 5th - 6th decades of life we selected the age of 50 for the comparative analysis of the results (51% of patients were under 50). No statistical age-group differences in antibody levels were found: mean TPOAb = 420.95 IU/ml, p = 0.840; mean TgAb = 327.98 IU/ml, p = 0.977. TSH mean was 2.14 [µIU/ml, with no significant age-group differences (p = 0.176). Se levels ranged between 8.05 - 998.50 µg/ with a mean value of 294.96 µg/L and no significant differences between age groups (p = 0.158). Thyroid ultrasound showed inhomogeneity in 89%, nodules in 35% of patients, and a mean thyroid volume of 11.72ml, with no significant age-group differences (p = 0.366). The low TSH levels were associated with low Se levels in 11.6% of cases, but the direct correlation was statistically insignificant (r = 0.116; R2 = 0.0161; p = 0.371). Depend ing on TSH percentiles, mean Selevels showed no significant differences, however pointing out the highest mean value at the 25th percentile (F = 0.441, df = 61, p = 0.646). A negative correlation trend was found between Se and TPOAb (r = -0.2276) or TgAb (r = -0.2190) but lacking statistical significance (p=0.099). CONCLUSION: Our results showed a weak negative correlation between Se and antithyroid antibodies, suggesting that selenium supplementation may improve the course of thyroid autoimmunity.

Renin and aldosterone reactions after acute hemorrhage.

Among the pressor homeostatic mechanisms that appear after hemorrhage are renin-angiotensin response and aldosterone hypersecretion. Plasma renin activity (PRA) may decrease initially but increase always after a certain interval. Aldosterone secretion increases or decreases in a higher or lower degree. It is generally accepted that Ang II is one of the principal factors that stimulates aldosterone secretion, but from our material it resulted that after hemorrhage it evolves independently. This discrepancy is more evident if hemorrhage is followed by bilateral nephrectomy (BN), when PRA significantly decreases but aldosterone secretion increases. After a simple BN, PRA decreases significantly but aldosterone plasma concentration increases, a discrepancy that is more evident if BN are followed by hemorrhage. Thus, it appears that after hemorrhage, the aldosterone secretion is not stimulated by the renin-angiotensin system.