To clarify the phylogenetic position of Xenoturbella bocki and hemichordates (Balanoglossus carnosus and Saccoglossus kowalevskii), which occupy an ambiguous evolutionary position between vertebrates and invertebrates, we expanded a pre-existing baseline vertebrate data set by incorporating randomly selected invertebrates. Based on nucleotide content calculated from complete mitochondrial genomes, invertebrates were classified into two groups, high C/G and low C/G, with vertebrates placed within the high-C/G invertebrate group. X. bocki and hemichordates (B. carnosus and S. kowalevskii) also fell into the high-C/G invertebrate group. We also analyzed amino acid composition and nucleotide content of complete mitochondrial genomes or 16S rRNA genes using Ward's clustering method and neighbor-joining. In the resulting phylogenetic trees, invertebrates are classified into high C/G and low C/G categories, and vertebrates are divided into terrestrial and aquatic groups. In addition, X. bocki and representative hemichordates B. carnosus and S. kowalevskii appear to be more closely related to vertebrates than to invertebrates.

Background: Eosinophilic gastrointestinal disorders (EGIDs) are disorders characterized by primary eosinophil inflammation in the gastrointestinal tract. There are a small number of reports of eosinophil infiltration in gastrointestinal tracts presenting as EGIDs in infants. In this study, we present Japanese cases of EGIDs in infants. Methods: Five patients diagnosed with or strongly suspected to have EGIDs in our hospital from 2008 to 2010 were reviewed. Radiographic contrast enema examinations and/or endoscopies were performed in 4 and 3 patients, respectively. Results: There were patients with eosinophilic colitis (1 suspected and 2 biopsy-proven), a patient who was suspected of having allergic eosinophilic enterocolitis, and a patient with eosinophilic gastroenteritis associated with pediatric hypereosinophilic syndrome. Conclusions: The causes and clinical findings of patients with intestinal eosinophil inflammation vary. Therefore, deliberate examination and observation are important for patients with infantile EGID.

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