There has been little exploration of major biologic regulators of cerebral development in autism. In archived neonatal blood of children with autistic spectrum disorders (n = 69), mental retardation without autism (n = 60), or cerebral palsy (CP, n = 63) and of control children (n = 54), we used recycling immunoaffinity chromatography to measure the neuropeptides substance P (SP), vasoactive intestinal peptide (VIP), pituitary adenylate cyclase-activating polypeptide (PACAP), calcitonin gene-related peptide (CGRP), and the neurotrophins nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin 3 (NT3), and neurotrophin 4/5 (NT4/5). Neonatal concentrations of VIP, CGRP, BDNF, and NT4/5 were higher (ANOVA, all p values < 0.0001 by Scheffe test for pairwise differences) in children in the autistic spectrum and in those with mental retardation without autism than in control children. In 99% of children with autism and 97% with mental retardation, levels of at least one of these substances exceeded those of all control children. Concentrations were similar in subgroups of the autistic spectrum (core syndrome with or without mental retardation, other autistic spectrum disorders with or without mental retardation) and in the presence or absence of a history of regression. Among children with mental retardation, concentrations did not differ by severity or known cause (n = 11, including 4 with Down syndrome). Concentrations of measured substances were similar in children with CP as compared with control subjects. SP, PACAP, NGF, and NT3 were not different by diagnostic group. No measured analyte distinguished children with autism from children with mental retardation alone. In autism and in a heterogeneous group of disorders of cognitive function, overexpression of certain neuropeptides and neurotrophins was observed in peripheral blood drawn in the first days of life.

The cffcet of ma8ncsium (ME)-dcficicnt culture on endothelial cell susceptibility to oxidativc stress was examined. Bovine endothelial eclls were cultured in tither control sufficient (0.8 mM) or deficient (0.4 mM) levuls of MgC13. Oxygen radicals wcrc produeed cxtmecllularly by the addition of dihydroxyfumaratc and Fe'+-ADP. Isolated Mg-deficient cndothclial eclls produced 2-to 3.fold higher levels of thiobarbituric acid (TBA)-reactive materials when incubated with this free radical syslem. Additional studies were pcrformcd using digitized video microscopy and 2',7'-dichlorofluoresoin diacetatc (DCFDA) as an intracellular indicator foroxidativc events at the sin&? ccl1 level. In rcsponx 10 theexogenousoxidativc stress, cndothelial eclls exhibited a time-dependent increase in fluoresccncc, sug8estivc of intracellular lipid peroxidation. The incrcasc in ecllular fluoresecnee began within 1 min of free radical addition; the Mg-dcficicnt cells exhibited a mote rapid increase in Ruorcsecnee than tbat of Mg-sufficient eells. In separate experiments, cellular viability was assessed using the Trypan blue exclusion assay. Mg deficiency increased cytotoxicity of the added oxyradicnls, but the loss of cellular viability began to occur only after 15 min of free radical exposure, lag& behind the detection of intracellular oxidation products. These results sugScst that increased oxidative cndothelial eel1 injury may eontributc to vaseuktr injury during Mg deficiency.

We have developed two rodent models of diet-induced magnesium-deficiency in which histologically defined cardiac lesions can be induced within two to three weeks. During the development of these lesions, the magnesium-deficient animals exhibit circulating cytokine levels which are indicative of a generalized inflammatory state. Dramatic elevations of the macrophage-derived cytokines, IL-1, IL-6, and TNF-alpha together with significantly elevated levels of the endothelial cell-derived cytokine, endothelin, were detected in the plasma of these animals. We believe that the pathophysiological effects caused by the action of these cytokines may play a role in the promotion of cardiovascular pathology associated with magnesium deficiency.

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