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Microbial dysbiosis has been suggested to be involved in the pathogenesis of Crohn's disease (CD); however, many studies of gut microbial communities have been confounded by environmental and patient-related factors. In this study, the microbial flora of fecal samples from 19 children newly diagnosed with CD and 21 age-matched controls were analyzed using high-throughput sequencing to determine differences in the microbial composition between CD patients and controls. Analysis of the microbial composition of specific bacterial groups revealed that Firmicutes percentages were significantly lower in CD patients than in controls and that this was due largely to changes in the class Clostridia. Bacteroidetes and Proteobacteria percentages were higher and significantly higher in CD patients than in controls, respectively. Both the detection frequencies of Bacteroidetes and Firmicutes correlated (positively and negatively, respectively) with the calculated pediatric Crohn's disease activity index scores of patients. Upon further analysis, differences in the microbial compositions of patients with mild disease and moderate to severe disease were identified. Our findings indicate that a combination of different bacterial species or a dynamic interplay between individual species is important for disease and is consistent with the dysbiosis hypothesis of CD.

The presence of Campylobacter concisus in the saliva of healthy individuals and patients with inflammatory bowel disease (IBD) was examined. C . concisus was detected in 97% of the healthy individuals and 100% of the patients with IBD tested. The C . concisus culture positivity rate in younger children was significantly lower than that in the other age groups.

The presence of Campylobacter species other than Campylobacter jejuni and antibodies to Campylobacter concisus in children were investigated. A significantly greater presence of C. concisus and higher levels of antibodies to C. concisus were detected in children with Crohn's disease (CD) than in controls. Campylobacter species other than C. jejuni were isolated from intestinal biopsy specimens of children with CD.

The results of experiments to explore the possible existence of a heat shock locus in Chironomus and Anopheles which may be comparable to the 93D heat shock locus of Drosophila, are presented. None of the heat shock loci in C. striatipennis were inducible by benzamide, colchicine, vitamin B6, thiamphenicol or a homogenate of heat shocked glands, all of which are known to selectively induce the 93D-like loci in the genus Drosophila. Benzamide also failed to induce any locus in A. stephensi. The effect of all these treatments on general transcription in Chironomus and Anopheles polytene nuclei were comparable to those known in polytene cells of Drosophila. It thus appears that a heat shock locus homologous to 93D of D. melanogaster is absent in Chironomus and Anopheles so far as inducibility of a puff by specific agents is concerned. The existence of a possible 'functional counterpart' of the 93D locus in Chironomus and Anopheles genomes cannot be eliminated.