Age-Related-Changes-of-Trace-Element-Contents-in-Intact-Thyroid-of-Females-Investigated-by-Neutron-Activation-Analysis

Abstract

IntroductionThe endocrine organs, including the thyroid gland, undergo important functional changes during aging and a prevalence of thyroid dysfunction is higher in the elderly as compared to the younger population [1,2]. Advancing age is known to influence the formation of adenomatous goiter and thyroid cancer [3]. The prevalence of thyroid nodules is increased in the elderly, reaching a frequency of nearly 50% by the age of 65 [4]. Both prevalence and aggressiveness of thyroid cancer increase with age [2]. Women are affected by thyroid nodule and cancer two to five times more often than men [2][3][4][5].Aging is a complex process involving biochemical and morphologic changes in single cells, in organs and in the whole organism. One of the most generally accepted explanations of how aging occurs at the molecular level is the oxidative stress hypothesis [6]. Reactive Oxygen Species (ROS) are widely considered to be a causal factor not only in aging but in a number of pathological conditions, including carcinogenesis. Aging, considered as an impairment of body functions over time, caused by the accumulation of molecular damage in DNA, proteins and lipids, is also characterized by an increase in intracellular oxidative stress due to the progressive decrease of the intracellular ROS scavenging [7]. Oxidative damage to cellular macromolecules which induce cancer can also arise through overproduction of ROS and faulty antioxidant and/or DNA repair mechanisms [8]. Overproduction of ROS is associated with inflammation, radiation and some other factors, including overload of some trace elements, in both blood and certain tissues, or deficiency of other trace elements with antioxidant properties [9][10][11][12][13][14][15]. Studies have shown that the imbalance in the composition of trace elements may cause different types of pathology. The importance of appropriate levels of many trace elements is indisputable, due to their beneficial roles when in specific concentration ranges, while on the other hand they can cause toxic effects with excessively high or low concentrations [12].In our previous studies [16][17][18][19][20][21][22][23][24] the high mass fraction of Iodine (I) and some other trace element were observed in intact human thyroid gland when compared with their levels in non-thyroid soft tissues of the human body. However, some questions about the age-dependence of trace element mass fraction in thyroid of adult, and particularly, elderly females still remain unanswered. One valuable way to elucidate the situation is to compare the mass fractions of trace elements in young adult (the control group) with those in older adult and geriatric thyroid. The findings of the excess or deficiency of trace element contents in thyroid and the perturbations of their relative proportions in glands of adult and elderly females, may give an indication of their role in a higher prevalence of thyroid dysfunction in the elderly. The reliable data on trace element mass fractions in normal geriatric thyroid is apparently extremel...

Twenty Chemical Element Contents in Normal and Cancerous Thyroid

“…In our previous study a significant positive correlation between age and some chemical element contents in the thyroid was observed [23][24][25][26][27][28]. It was concluded that an age-dependent excess of intra-thyroidal I and zinc (Zn) concentration are probably one of the factors acting in both initiation and promotion stages of thyroid carcinogenesis [9,24,25], as it was earlier shown by us for I in thyroid and for Zn in prostate gland [29][30][31][32][33][34]. Moreover, it seems fair to suppose that besides I and Zn, many other chemical elements also play a role in the pathophysiology of the thyroid.…”

“…The content of Br, Ca, Cl, I, K, Mg, Mn, and Na were determined by INAA-SLR using a horizontal channel equipped with the pneumatic rabbit system of the WWR-c research nuclear reactor (Branch of Karpov Institute, Obninsk). Details of used neutron flux, nuclear reactions, radionuclides, gamma-energies, and spectrometric unit were presented in our earlier publications concerning the INAA-SLR chemical element contents in human thyroid, scalp hair, and prostate [7,23,27,40] In a few days after INAA-SLR all thyroid samples were repacked separately in a high-purity aluminum foil washed with rectified alcohol beforehand and placed in a nitric acid-washed quartz ampoule and used for INAA-LLR. A vertical channel of the WWR-c research nuclear reactor (Branch of Karpov Institute, Obninsk).was applied to determine the content of Ag, Co, Cr, Fe, Hg, Rb, Sb, Sc, Se, and Zn by INAA-LLR.…”

Trace Element Contents in Thyroid Cancer Investigated by Energy Dispersive X-Ray Fluorescent Analysis

“…An overload of Rb could modulate proliferative responses of the cell, as was shown for bone marrow leukocytes [19]. In our previous studies it was found a significant age-related increase of Rb content in female thyroid [23,[26][27][28]. Therefore, a goitrogenic and, probably, carcinogenic effect of excessive Rb level in the thyroid of old females was assumed.…”

“…In our previous studies it was found a significant age-related increase of Br content in human thyroid [23,[26][27][28]. Therefore, a goitrogenic and, probably, carcinogenic effect of excessive Br level in the thyroid of old females was assumed.…”

“…In our previous study a significant positive correlation between age and some trace element contents in the thyroid was observed [23][24][25][26][27][28]. For example, a strongly pronounced tendency of age-related increase in bromine (Br), coper (Cu), rubidium (Rb) and zinc (Zn) mass fraction was demonstrated by us using 109 Cd radionuclide-induced energy dispersive X-ray fluorescent (EDXRF) analysis [26,28].…”