Table 1.

NO/ONOO(-) elements that are raised in autism/ASDs.

Peroxynitrite (ONOO-)	Peroxynitrite was shown to be elevated in autism based on a test using 3-nitrotyrosine as a specific marker for peroxynitrite (Sajdel-Sulkowska et al. [213]; De Felice et al. [214]; Nadeem et al. [215,216]; Algahtani et al. [217]; Carey et al. [218]). Peroxynitrite elevation by the NO/ONOO(-) cycle, as discussed here and in thousands of other papers, produces oxidative stress. Peroxynitrite is scavenged through its reaction oxidizing 5-methyltetrahydrofolate (5-MTHF) [219,220], thus depleting cells of a very important methyl donor, while lowering peroxynitrite. These properties of peroxynitrite mean that both the oxidative stress and the low methylation status of autism patients reported by James et al. [221] may be a consequence of peroxynitrite elevation.
Oxidative stress	See above. There are dozens of papers showing oxidative stress in people with autism/ASDs, as well as in animal models. The following examples each provide strong evidence for an oxidative stress role in ASD causation: Carey et al. [218]; De Felice et al. [214]; Golomb [212]; James et al. [221]; McGinnis [94]; Nadeem et al. [215,216]; Saidel-Sulkowska et al. [213], and Bjorklund et al. [222].
NF-kappaB	NF-kappaB has been among the less studied of the measurable elements of the cycle in autism. NF-kappaB has been found to be elevated in cases of autism in Young et al. [223]; Nadeen et al. [216]; Liao and Li [52], and Theoharides et al. [224]. Young et al. [223] may be of special interest, in that the paper was completely focused on NF-kappaB measurements. They used an immunoassay for NF-kappa that can be scored under a microscope, studying post-mortem orbitofrontal cortex brain tissues of patients with ASDs and matched normal controls. Young et al. [223] found very highly statistically significant elevation of NF-kappaB in ASD vs. controls in each of the three cell types studied, neurons, astrocytes, and microglia. They also found that there were similar elevations in both the nuclear localized and extranuclear NF-kappaB in ASD tissues. Because the NO/ONOO(-) cycle predicts cycle elevation of the synthesis of NF-kappaB, these findings are in good agreement with prediction. Alomar et al. [225] showed that NF-kappaB elevation has a causal role in a mouse model of autism.
Inflammatory cytokines	Eftekharian et al. [226] found that each of the five inflammatory cytokines predicted to be directly raised by NF-kappaB elevation were raised in autism patients, as well as several other cytokines. Theoharides et al. [224], Kutuk et al. [227], and Ferencova et al. [228] found, similarly, in their large studies, that the same five inflammatory cytokines directly raised by NF-kappaB were elevated in patients with ASDs, as were multiple additional cytokines. Mehta et al. [229] showed that four of those five cytokines (all except IFNγ) were elevated in a rat model of ASD.
Mitochondrial dysfunction	Mitochondrial dysfunction has been demonstrated in individuals with autism/ASDs. Napolioni et al. [230] ascribed much of the mitochondrial dysfunction seen in those with ASDs to the dysfunction of the calcium-regulated aspartate/glutamate carrier. Others reviewing mitochondrial dysfunction in autism include Golomb [212], Rossignol and Frye [231], and Palmieri and Persico [232]. When Palmieri and Persico [232] asked whether mitochondrial dysfunction is either the cause or effect of ASDs, they concluded it is both, consistent with the NO/ONOO(-) cycle predictions that all cycle elements must be both cause and effect.
[Ca2+]i	Autism/ASDs caused by excessive [Ca2+]i has been documented throughout this paper.
Tetrahydrobiopterin (BH4) depletion	Tani et al. [233] and Frye [234,235] have each demonstrated a deficiency of tetrahydrobiopterin (BH4) in autism patients. A series of studies have each shown that BH4 supplementation is useful in autism treatment (Naruse et al. [236]; Takesada et al. [237]; Frye [234]). The NO/ONOO(-) cycle produces, as part of the cycle, peroxynitrite-mediated oxidation of BH4 to dihydrobiopterin (BH2), thus lowering BH4 levels. Consequently, BH4 supplementation will not only provide the BH4 cofactor for several enzymes, including the nitric oxide synthases, lowering the NO/ONOO(-) cycle in that way, but will also lower peroxynitrite by chemically reacting with it, lowering the cycle in a second way.
iNOS	iNOS has been found to be elevated in patients with ASDs (Nadeem et al. [215,216]). Mehta et al. [226] showed that iNOS was elevated in a rat model of ASDs.
Nitric oxide (NO)	Several reviews documented elevated nitric oxide in patients with ASDs, including Nadeem et al. [215,216] and Tripathy et al. [238]). Mehta et al. [229] showed that nitric oxide was elevated in a rat model of ASDs.
RhoA	In the paper showing that the NO/ONOO(-) cycle is central to the etiology of heart failure, it was shown that RhoA functioned as possibly tissue-limited cycle element [209]. RhoA is implicated as a causal element of autism/ASDs, including in stabilization of synapses (Richter et al. [239]; Luo et al. [240]. Hayashi et al. [241]), providing further evidence consistent with a NO/ONOO(-) cycle role in autism/ASDs.