(A) primary human neuronal-glial (HNG) cells after ~2 weeks in primary co-culture; the cell density is approximately 75% neurons and 25% astroglia at ~70% confluency; human primary neuronal and glial “support” cell co-cultures are utilized because human neuronal cells do not culture well by themselves (28–32); HNG cells are triple stained; neuronal cells are stained with neuron-specific β-tubulin (red; λmax=690 nm), glial cells are stained with glial-specific glial fibrillary acidic protein (GFAP; green; λmax=525 nm), and nuclei are stained with DAPI/Hoechst 33258 stain (blue; λmax=470 nm); photo magnification ~30x; (B) ELISA results presented in bar graph format using an NF-κB (p65) transcription factor assay (Cat № 10007889 kit; Cayman Chemical, Ann Arbor MI USA; https://www.caymanchem.com/pdfs/10007889.pdf) to measure effects of incubation with 0, 20, 50, 200, 500 or 1000 nM ambient aluminum sulfate or mercury sulfate either alone or together; detection of NF-kB p65 is the equivalent of the NF-kB p50/p65 complex since the p65 subunit is always associated with the p50 subunit and is seldom found as a discrete single entity [,,,]; aluminum and mercury sulfate together exhibited synergistic induction of the pro-inflammatory transcription factor NF-kB (p65) under the conditions used; see text for further details); experiments were performed N=3 to 5 times per concentration analyzed; the background reading of 0.1 was established at ‘0 nM’ on the ‘x’ axis which was used for a comparison against all other levels; a dashed horizontal line at 0.1 has been added for ease of comparison; *p<0.05; **p<0.01, ***p<0.001, ANOVA)