Evaluation of osteoporotic bone structure through synchrotron radiation X-ray microfluorescence images.

The abnormal accumulation or deficiency of trace elements may theoretically impair the formation of bone and contribute to osteoporosis. In this context, the knowledge of major and trace elements is very important in order to clarify many issues regarding diseases of the bone, such as osteoporosis, that remain unresolved. Several kinds of imaging techniques can be useful to access morphology and the minerals present in osteoporotic bones. In this work, synchrotron radiation X-ray microfluorescence was used as an X-ray imaging technique to investigate bone structures. Therefore, this research aims to improve the knowledge about some aspects of bone quality. The measurements were carried out at the Brazilian Synchrotron Laboratory Light Laboratory, in Brazil. A white beam with an energy range of 4-23 keV, a 45 degrees /45 degrees geometry and a capillary optics were used. It was demonstrated that bone quality can and must be evaluated not only by considering the architecture of bones but also by taking into account the concentration and the distribution of minerals. Our results showed that the elemental distributions in bone zones on a micron scale were very helpful to understand functions in those structures.

Effects of aging on thyroidal function and proliferation.

The endocrine system is as affected by aging as are other systems. The effect of aging on the hypothalamus-pituitary-thyroid function is still controversial. Human aging was reported as associated with a decrease in thyrotropin (TSH) secretion, but increased TSH levels in relatively healthy elders are also reported. The main point discussed is whether this increase in the immunoreactive TSH of aged subjects, and related changes in thyroid function, are "physiologic" consequences of aging on the hypothalamus-pituitary-thyroid axis or are induced by non-thyroid illnesses and/or drug use, frequent in the elderly. There are strong evidences of decreased hypothalamus-pituitary-thyroid axis activity as well as decreased thyroxine metabolism (5'-deiodination) in humans, and other mammals. For now, we must consider that the hypothalamus-pituitary-thyroid axis is affected at all three levels by normal aging, and the mild state of "total" hypothyroidism during aging is completed by a reduced response of target cells/tissues to thyroid hormones. Despite the decreased response of the old rat thyroid to TSH there is no decrease in the glands mass. Ras proteins are involved in the transduction of growth factor signals by surface receptors, in thyroid as well as in other tissues, and are key components of downstream signaling through several pathways. Ras activation of Raf, and of extracellular-signal-regulated kinases (ERK) is an important signaling pathway for many Ras effects. Very little is known about the modulation of Ras expression in the aging thyroid. We detected an increase in Ras expression in thyroids of old rats, but the signal transduction by pERK was decreased, suggesting that another RAS-signaling pathway could be activated and responsible for the maintenance of the thyroid volume.