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Urinary peptide levels and patterns in autistic children from seven countries, and the effect of dietary intervention after 4 years

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Abstract

Urinary samples from children with autistic syndromes, diagnosed according to the DSM III, were collected from seven different countries. The excretion of peptides was analyzed by a new and fast HPLC method, and the increased amount excreted was observed to be statistically the same. A 4-year follow-up of the original cohort of autistic children placed on a diet free of gluten and milk protein showed that those on the diet continued to develop, while those who stopped the diet regressed. The possible and probable etiological relationship of our data to the phenolsulphotransferase data of Waring is outlined.
... There have been various theories proposed to explain how impaired GI function may disturb neurological development and/or function resulting in autism, including absorption of opioid-like peptides that are derived from gluten and casein (i.e. the 'opioid excess theory' , Reichelt et al. 1997), GI overgrowth of neurotoxic bacteria and dysfunction of secretin or its receptors (Shattock & Whiteley 2002, Molloy & Manning-Courtney 2003, Sandler et al. 2000, Horvath et al. 1999. Functional changes have also been reported in the GI tracts of children with autism including increased intestinal permeability, i.e. a 'leaky gut' , and decreased digestive enzyme activity (Horvath & Perman 2002a). ...
... Shattock and Whiteley (2002) have suggested that because of its planar geometry, indolyl-3-acrylic acid (IAA), the acid precursor of IAG may disrupt membrane structures, and in turn increase the permeability of membranes. Then, excessive levels of endogenous opioid-like peptides as described by Reichelt et al. (1997) pass through the intestinal and blood-brain barrier into the brain, which increase social withdrawal and stereotypic behaviours and underpins the aetiology of ASD. ...
... (iv) Biochemical/endocrine endophenotypes: hyperserotoninemia [4749], oligopeptiduria [50], urinary dopamine and HVA levels [51], decreased plasma fatty acids [52], decreased melatonin plasma levels [53]; ...
... In our experimental design, we have implemented several biochemical and morphological endophenotypes, namely head circumference, serotonin blood levels, and urinary oligopeptides. In fact, macrocephaly (i.e., head circumference >97th percentile) has been consistently described in approximately 20% of autistic children [55,58,59], serotonin blood levels are elevated in 20%50% of autistic subjects [47], and increased urinary excretion rates of oligopeptides and multiple solutes is found in 20-60% of autistic patients, with significant interethnic differences [50,60,61]. The implementation of these endophenotypes in our studies is detailed in the following section. ...
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Autism is a complex neuropsychiatric disorder of developmental origin, where multiple genetic and environmental factors likely interact resulting in a clinical continuum between "affected" and "unaffected" individuals in the general population. During the last two decades, relevant progress has been made in identifying chromosomal regions and genes in linkage or association with autism, but no single gene has emerged as a major cause of disease in a large number of patients. The purpose of this paper is to discuss specific methodological issues and experimental strategies in autism genetic research, based on fourteen years of experience in patient recruitment and association studies of autism spectrum disorder in Italy.
... Focusing on autism, the first studies investigating the efficacy of a gluten-and casein-free diet were conducted in the 1990s and were mostly uncontrolled trials (i.e., [107][108][109] Although all these reports showed a significant improvement of ASD symptoms after the elimination diet, there were several methodological flaws, such as the lack of a control group, poor diagnostic characterization, small sample sizes, use of unstandardized outcome measures, and absence of control on dietary adhesion. The first randomized controlled trial was done in 2002 [13]: the authors enrolled 10 pairs of autistic children matched for age, cognitive level, and severity. ...
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Background. Complementary and alternative medicine (CAM) represents a popular therapeutic option for patients with autism spectrum disorder (ASD). Unfortunately, there is a paucity of data regarding the efficacy of CAM in ASD. The aim of the present systematic review is to investigate trials of CAM in ASD. Material and Methods. We searched the following databases: MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, CINAHL, Psychology and Behavioral Sciences Collection, Agricola, and Food Science Source. Results. Our literature search identified 2687 clinical publications. After the title/abstract screening, 139 publications were obtained for detailed evaluation. After detailed evaluation 67 studies were included, from hand search of references we retrieved 13 additional studies for a total of 80. Conclusion. There is no conclusive evidence supporting the efficacy of CAM therapies in ASD. Promising results are reported for music therapy, sensory integration therapy, acupuncture, and massage.
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Introdução: A dieta sem glúten e sem caseína é uma prática comum no Transtorno do Espectro Autista, mas sem consenso quanto ao seu benefício clínico ou cognitivo. Objetivo: Revisar sistematicamente a literatura que avalia a isenção de glúten e/ou caseína da dieta para indivíduos com Transtorno do Espectro Autista. Materiais e Métodos: Revisão sistemática de literatura analisando estudos originais disponíveis até dezembro/2016 nas bases de dados: PubMed, SciELO, LILACS e BDENF. Os termos usados para a pesquisa foram: autismo, espectro autista, autismo e sem glúten, autismo e dieta livre de caseína. Para melhor direcionamento da busca de dados foi utilizado o método PICO (população, intervenção, comparação e desfecho). Resultados: No total, foram incluídos 22 artigos, sendo 13 ensaios clínicos randomizados, 4 estudos de caso, 4 transversais e 1 coorte. Do total, 15 encontraram uma associação positiva de intervenção para os resultados avaliados e 7 não encontraram associação significativa. Discussão: Foi encontrada grande variabilidade do tamanho amostral, idade, tempo de intervenção, cegamento, controle ou análise dietética mais apurada. Conclusões: não há evidências científicas para apoiar o uso de uma dieta livre de glúten e caseína em pacientes com Transtorno do Espectro Autista. Há necessidade de novos estudos bem delineados, principalmente ensaios clínicos randomizados bem controlados, cegos, com cálculos amostrais que permitam um poder de observação apropriado, para maior segurança nessa prática. Como citar este artigo: Dias EC, Rocha JS, Ferreira GB, Pena GG. Dieta isenta de glúten e caseína no transtorno do espectro autista: uma revisão sistemática. Rev Cuid. 2018; 9(1): 2059-73. http://dx.doi.org/10.15649/cuidarte.v9i1.485
Chapter
Autism spectrum disorder (ASD) is a complex disease with onset during early childhood and typically a lifelong course. Genetic liability plays a prominent role in ASD, as siblings of affected individuals display on average 25-fold higher autism risk rates compared to the general population. However, genetic contributions fit in most cases with complex, “multiple-hit,” oligogenic/polygenic models encompassing several loci and also gene-environment interactions. Furthermore, ASD should be viewed as the extreme end of a set of continuous dimensions pertaining to the realms of human socialization, language development, and behavior, rather than as a “black or white” medical condition. This complexity spurs interest into the heuristic potential of “endophenotypes” in ASD, as originally applied by Gottesman and Shields (Br J Psychiatry 122:15–30, 1973) to the realm of psychiatry. Endophenotypes can be defined as familial, heritable, and quantitative traits associated with a complex disease. Occupying an intermediate position between genotype and behavior, these traits offer the potential to bridge the gap between complex disease phenotypes, such as autism, and the underlying genetic mechanisms. The most reliable endophenotypes in ASD can be grouped into seven categories: biochemical, morphological, hormonal, immunological, neurophysiological/neuroanatomical, neuropsychological, and behavioral. Their use holds promise to foster advances not only toward more reliable genotype-phenotype correlations in autism research but also in dissecting clinical subgroups of ASD patients with relatively homogeneous pathophysiological underpinnings, aiding clinicians in early diagnosis once incorporated into broader biomarker panels, and predicting developmental trajectories and treatment response.
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Although mutations in the MECP2 gene are associated with many cases of Rett syndrome (RS), the phenotype remains unexplained. At least in the early stages, RS and autism have common features; urinary analysis of autistic children has shown an abnormal profile of excretion of sulphur-containing anions, with high levels of sulphite, sulphate and thiosulphate and low values for thiocyanate ions. These parameters were therefore studied in an RS population. Levels of urinary peptides, protein, cysteine, free sulphate, conjugated sulphate, sulphite, thiosulphate and thiocyanate were determined in female RS patients (n=21) and in controls n=21), using standard methods. The urinary volumes were adjusted to standard creatinine levels (200 nmol/mL). Children with RS had higher urinary peptides and protein excretion. Free sulphate values and total sulphate excretion were higher in RS (P<0.001) than in controls. Cysteine, sulphite and thiosulphate excretion were elevated (P<0.001) while thiocyanate excretion was greatly reduced (P<0.001). These results are consistent with reduced expression or activity of the enzyme rhodanese (thiosulphate cyanide sulphurtransferase). Other mutation(s) in genes involved in metabolism of sulphur anions may also contribute to the RS phenotype.
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It has been hypothesized that autism results from an 'opioid peptide excess'. The aims of this study were to (1) confirm the presence of opioid peptides in the urine of children with autism and (2) determine whether dipeptidyl. peptidase IV (DPPIV/CD26) is defective in children with autism. Opioid peptides were not detected in either the urine of children with autism (10 children; nine males, one female; age range 2 years 6 months to 10 years 1 month) or their siblings (10 children; seven males, three females; age range 2 years 3 months to 12 years 7 months) using liquid chromatography-ultraviolet-mass spectrometric analysis (LC-UV-MS). Plasma from 11 normally developing adults (25 years 5 months to 55 years 5 months) was also tested. The amount and activity of DPPIV in the plasma were quantified by an ELISA and DPPIV enzyme assay respectively; DPPIV was not found to be defective. The percentage of mononuclear cells expressing DPPIV (as CD26) was determined by flow cytometry. Children with autism had a significantly lower percentage of cells expressing CD3 and CD26, suggesting that they had lower T-cell numbers than their siblings. In conclusion, this study failed to replicate the findings of others and questions the validity of the opioid peptide excess theory for the cause of autism.
Conference Paper
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