Proposed toxic and hypoxic impairment of a brainstem locus in autism.

Electrophysiological findings implicate site-specific impairment of the nucleus tractus solitarius (NTS) in autism. This invites hypothetical consideration of a large role for this small brainstem structure as the basis for seemingly disjointed behavioral and somatic features of autism. The NTS is the brain's point of entry for visceral afference, its relay for vagal reflexes, and its integration center for autonomic control of circulatory, immunological, gastrointestinal, and laryngeal function. The NTS facilitates normal cerebrovascular perfusion, and is the seminal point for an ascending noradrenergic system that modulates many complex behaviors. Microvascular configuration predisposes the NTS to focal hypoxia. A subregion--the "pNTS"--permits exposure to all blood-borne neurotoxins, including those that do not readily transit the blood-brain barrier. Impairment of acetylcholinesterase (mercury and cadmium cations, nitrates/nitrites, organophosphates, monosodium glutamate), competition for hemoglobin (carbon monoxide, nitrates/nitrites), and higher blood viscosity (net systemic oxidative stress) are suggested to potentiate microcirculatory insufficiency of the NTS, and thus autism.

Discerning the Mauve factor, Part 2.

"Mauve Factor" was once mistaken for kryptopyrrole but is the hydroxylactam of hemopyrrole, hydroxyhemopyrrolin-2-one (HPL). Treatment with nutrients--particularly vitamin B6 and zinc--reduces urinary excretion of HPL and improves diverse neurobehavioral symptoms in subjects with elevated urinary HPL. Heightened HPL excretion classically associates with emotional stress, which in turn is known to associate with oxidative stress. For this review, markers for nutritional status and for oxidative stress were examined in relationship to urinary HPL. In cohorts with mixed diagnoses, 24-hour urinary HPL correlated negatively with vitamin B6 activity and zinc concentration in red cells (P < .0001). Above-normal HPL excretion corresponded to subnormal vitamin B6 activity and subnormal zinc with remarkable consistency. HPL correlated inversely with plasma GSH and red-cell catalase, and correlated directly with plasma nitric oxide (P < .0001). Thus, besides implying proportionate needs for vitamin B6 and zinc, HPL is a promising biomarker for oxidative stress. HPL is known to cause non-erythroid heme depression, which lowers zinc, increases nitric oxide, and increases oxidative stress. Administration of prednisone reportedly provoked HPL excretion in animals. Since adrenocorticoid (and catecholamine) stress hormones mediate intestinal permeability, urinary HPL was examined in relationship to urinary indicans, presumptive marker for intestinal permeability. Urinary HPL associated with higher levels ofindicans (P < .0001). Antibiotics reportedly reduce HPL in urine, suggesting an enterobic role in production. Potentially, gut is reservoir for HPL or its precursor, and stress-related changes in intestinal permeability mediate systemic and urinary concentrations.

Discerning the Mauve Factor, Part 1.

"Mauve Factor" was once mistaken for kryptopyrrole but is the hydroxylactam of hemopyrrole, hydroxyhemopyrrolin-2-one (HPL). Treatment with nutrients--particularly vitamin B6 and zinc--reduces urinary excretion of HPL and improves diverse neurobehavioral symptoms in subjects with elevated urinary HPL. Heightened HPL excretion classically associates with emotional stress, which in turn is known to associate with oxidative stress. For this review, markers for nutritional status and for oxidative stress were examined in relationship to urinary HPL. In cohorts with mixed diagnoses, 24-hour urinary HPL correlated negatively with vitamin B6 activity and zinc concentration in red cells (P < .0001). Above-normal HPL excretion corresponded to subnormal vitamin B6 activity and subnormal zinc with remarkable consistency. HPL correlated inversely with plasma glutathione and red-cell catalase, and correlated directly with plasma nitric oxide (P < .0001). Thus, besides implying proportionate needs for vitamin B6 and zinc, HPL is a promising biomarker for oxidative stress. HPL is known to cause non-erythroid heme depression, which lowers zinc, increases nitric oxide, and increases oxidative stress. Administration of prednisone reportedly provoked HPL excretion in animals. Since adrenocorticoid (and catecholamine) stress hormones mediate intestinal permeability, urinary HPL examined in relationship to urinary indicans, presumptive marker for intestinal permeability. Urinary HPL associated with higher levels of indicans (P < .0001). Antibiotics reportedly reduce HPL in urine, suggesting an enterobic role in production. Potentially, gut is a reservoir for HPL or its precursor, and stress-related changes in intestinal permeability mediate systemic and urinary concentrations.

Altered vascular phenotype in autism: correlation with oxidative stress.

BACKGROUND: Autism is a neurologic disorder characterized by impaired communication and social interaction. Results of previous studies showed biochemical evidence for abnormal platelet reactivity and altered blood flow in children with autism. OBJECTIVE: To evaluate the vascular phenotype in children with autism. DESIGN AND MAIN OUTCOME MEASURES: Urinary levels of isoprostane F(2alpha)-VI, a marker of lipid peroxidation; 2,3-dinor-thromboxane B(2), which reflects platelet activation; and 6-keto-prostaglandin F(1alpha), a marker of endothelium activation, were measured by means of gas chromatography-mass spectrometry in subjects with autism and healthy control subjects. SETTING AND SUBJECTS: Children with a clinical diagnosis of autism attending the Pfeiffer Treatment Center. RESULTS: Compared with controls, children with autism had significantly higher urinary levels of isoprostane F(2alpha)-VI, 2,3-dinor-thromboxane B(2), and 6-keto-prostaglandin F(1alpha). Lipid peroxidation levels directly correlated with both vascular biomarker ratios. CONCLUSION: Besides enhanced oxidative stress, platelet and vascular endothelium activation also could contribute to the development and clinical manifestations of autism.

Oxidative stress in autism.

STATEMENT OF PURPOSE: Indirect markers are consistent with greater oxidative stress in autism. They include greater free-radical production, impaired energetics and cholinergics, and higher excitotoxic markers. Brain and gut, both abnormal in autism, are particularly sensitive to oxidative injury. Higher red-cell lipid peroxides and urinary isoprostanes in autism signify greater oxidative damage to biomolecules. A preliminary study found accelerated lipofuscin deposition--consistent with oxidative injury to autistic brain in cortical areas serving language and communication. Double-blind, placebo-controlled trials of potent antioxidants--vitamin C or carnosine--significantly improved autistic behavior. Benefits from these and other nutritional interventions may be due to reduction of oxidative stress. Understanding the role of oxidative stress may help illuminate the pathophysiology of autism, its environmental and genetic influences, new treatments, and prevention. OBJECTIVES: Upon completion of this article, participants should be able to: 1. Be aware of laboratory and clinical evidence of greater oxidative stress in autism. 2. Understand how gut, brain, nutritional, and toxic status in autism are consistent with greater oxidative stress. 3. Describe how anti-oxidant nutrients are used in the contemporary treatment of autism.