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. 2021 Apr 19;12:652675. doi: 10.3389/fendo.2021.652675

Figure 1.

Figure 1

(A) Chronic exposure of human thyrospheres (aggregates of stem/precursor thyroid cells) to heavy metals at the indicated salt concentrations significantly increased BrdU incorporation in all cases. Basal values in untreated cells were always considered equal 100 and values of BrdU incorporation after cell exposure to metals were expressed as percent changes over basal. The dose-response curves followed in all cases a biphasic pattern, declining after the peak value when metal concentrations were further increased. Data shown for each metal indicate the average values ± SEM of four separate experiments except for W (ten separate experiments). In differentiated thyrocytes none of the five heavy metals studied or their mixture had any effect on BrdU incorporation. *p < 0.05, **p < 0.01 and ***p < 0.001 vs. 0. (B) The mixture of the five metals studied (Mix), each at the concentration causing the maximum BrdU incorporation, promoted BrdU incorporation significantly more than control thyrospheres (CTRL) and also significantly more than each metal acting alone (average values ± SEM of four separate experiments). *p < 0.05, **p < 0.01 and ***p < 0.001 vs. Mix.