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Brief Review: Rethinking Colonic Redundancy in Gastroenterology.

BACKGROUND: Dolichocolon (DC), or colonic redundancy, is an elongated and tortuous colon described as early as 1820, yet it remains underrecognized in clinical gastroenterology. Advances in imaging and motility assessment offer new insights into its prevalence, mechanisms, and clinical implications. AIMS: To summarize current evidence on the anatomy, epidemiology, and potential clinical significance of DC and to explore possible pathophysiological mechanisms linking this variant to gastrointestinal disorders. METHODS: A targeted literature review of studies published between 1900 and 2024 was conducted using PubMed and Scopus with search terms including dolichocolon, colonic redundancy, and redundant colon. Publications addressing anatomy, motility, symptom associations, and disease relevance were included. RESULTS: Though epidemiological data are limited, it has been estimated that DC affects 10-20% of the population and is associated with constipation, volvulus, and, possibly, inflammatory bowel disease. Proposed mechanisms include segmental stasis and ischemia in redundant loops, altered neuromuscular signaling, and increased mucosal surface area promoting immune-microbiota interactions. Despite its potential importance, DC is rarely noted in modern radiology reports, contributing to under-recognition in clinical practice. CONCLUSIONS: Colonic redundancy represents a common anatomic variant with potentially overlooked clinical implications. Standardized radiologic characterization and prospective studies are needed to clarify its role in gastrointestinal disorders and to guide future diagnostic and therapeutic approaches.

Humans

Dolichocolon May Differentially Associate with Ulcerative Colitis Phenotype in Children.

BACKGROUND: Dolichocolon (DC) is an underrecognized anatomic variant associated with constipation; its association with ulcerative colitis (UC) is unknown. METHODS: We retrospectively reviewed abdominal MRI and CT scans in children with UC, Crohn's disease (CD), and non-inflammatory bowel disease (non-IBD) controls, classifying DC subtypes. RESULTS: A total of 111 cases (66 with UC) were examined. DC was similarly common (p = 0.4436) in patients with constipated (69%) or non-constipated (NC-UC: 57%) UC. In non-constipated (NC) patients, DC prevalence was higher in children with UC than those with CD or controls. Type 1 DC predominated in NC children with proctitis/left-sided UC (E1/E2), while Type 2 DC was enriched in children with extensive/pancolitis (E3/E4). DISCUSSION: DC may be associated with different phenotypes of UC and may influence disease distribution independent of constipation. However, given the cross-sectional design of this study, these associations should be interpreted cautiously and require confirmation in longitudinal studies.

Humans

Genome-resolved analysis of colonization factor repertoires reveals ecological stratification in cervid gut microbiomes.

INTRODUCTION: Colonization factors (CFs) are important microbial traits associated with persistence and host adaptation in the gut, yet their large-scale organization in cervid gut microbiomes remains unclear. METHODS: A total of 3,311 non-redundant high-quality metagenome-assembled genomes (MAGs), derived from 688 cervid gut metagenomic samples across 15 publicly available projects and one in-house dataset, were analyzed. CF-associated genes were identified by comparison against the GHA CF database, and CF repertoires were characterized at genome, host-species, and gastrointestinal-segment levels. RESULTS: A total of 138,729 CF-associated genes spanning 71 CF families were identified. MAGs from Cervinae contained richer CF repertoires than those from Caprinae, and CF47 (Peptidase_C69), CF24_29 (QueH), and CF18 (Glycos_transf_2) were among the most prevalent families. CF repertoires were strongly structured by taxonomy, showed a moderate association with bacterial phylogenetic distance, and formed two recurrent genome-level configurations with distinct KEGG functional profiles. Integration of sample metadata further revealed differentiation of CF repertoires across host species and gastrointestinal segments, representing the major ecological dimensions examined in this study. Segment-associated CF variation was accompanied by redistribution of broader functional profiles, including enrichment of carbohydrate and lipid metabolism in the jejunum, membrane transport in the ileum, xenobiotics biodegradation in the cecum, and environmental adaptation in the rumen. DISCUSSION: These findings provide a genome-resolved view of CF repertoire organization in cervid gut microbiomes and demonstrate that colonization-associated functions are structured across microbial lineages and ecological contexts. This study highlights the importance of considering microbial taxonomy and host-associated environments when interpreting the distribution of CF repertoires in mammalian gut ecosystems.

Cervidae

Transcriptomic responses of Porphyrophora sophorae larvae during licorice root colonization reveal coordinated remodeling of translation, mitochondrial energy metabolism and defense-related genes.

BACKGROUND: Porphyrophora sophorae is a subterranean piercing-sucking scale insect that damages licorice (Glycyrrhiza uralensis) roots, but the molecular responses associated with larval root colonization remain insufficiently defined. METHODS: We compared non-parasitic larvae (NP) and root-colonizing larvae (RC) using six RNA-seq libraries, de novo transcriptome assembly, DESeq2-based differential expression analysis, GO/KEGG enrichment, annotation-based candidate gene screening, and RT-qPCR validation of selected genes. RESULTS: Sequencing yielded 260.91 million clean reads, and de novo assembly produced 60,794 non-redundant transcripts. DESeq2 identified 703 FDR-significant DEGs, including 49 upregulated and 654 downregulated genes in RC larvae. Upregulated genes were mainly associated with translation- and ribosome-related processes, whereas downregulated genes were enriched in mitochondrial, oxidation-reduction, energy metabolism, and oxidative phosphorylation-related functions. Annotation-based screening identified 75 FDR-significant candidate genes associated with chemosensation, defense-related responses, and energy metabolism, with mitochondrial energy metabolism-related genes forming the largest module. RT-qPCR validation based on the raw Ct data showed concordant expression directions for ten selected transcript targets. CONCLUSIONS: Root colonization in P. sophorae larvae was associated with coordinated transcriptional remodeling involving selective activation of translation-related processes, adjustment of mitochondrial energy metabolism, and changes in defense-related gene expression. These results provide candidate molecular targets for future functional studies of host contact, feeding establishment, and physiological adjustment in this subterranean scale insect.

Animals

Bacteriophages Control Epiphytic Pseudomonas syringae Populations in Highbush Blueberry Leaves.

The Pseudomonas syringae complex (Psc) is a group of globally distributed phytopathogens responsible for substantial agricultural losses. Although bacteriophage-based biocontrol has shown promise against Psc, no studies have examined phages targeting blueberry-tropic Psc lineages. Here, we isolated phages infecting Psc strains from diseased highbush blueberry (Vaccinium corymbosum), and evaluated their suitability for biocontrol using a multi-stage screening pipeline incorporating host-range analysis, comparative genomics, environmental stability testing, in vitro antibacterial efficacy assays and ex planta validation. Twelve of the isolated phages exhibited favourable host-range characteristics. Genomic analyses revealed substantial phylogenetic diversity among these candidates but simultaneously identified multiple clonal groups, reducing the collection to eight non-redundant phages spanning five distinct genera. Candidate phages generally retained infectivity under environmentally relevant conditions and exhibited heterogeneous but largely favourable stability profiles. Planktonic killing assays uncovered considerable variation in antibacterial efficacy, but phage performance appeared to be driven by infection compatibility and host-specific factors rather than properties intrinsic to individual phages. Notably, the jumbo phageCB10 emerged as a particularly promising candidate due to its strong antibacterial activity (median GRC = 0.943), favourable environmental stability and unique genomic features. Cocktails containing the most effective candidates produced substantial and longitudinally sustained reductions in epiphytic colonization of detached blueberry leaves by Psc, exceeding five orders of magnitude at peak efficacy and demonstrating robust activity in a biologically relevant ex planta system. Importantly, in vitro antibacterial efficacy was predictive of performance in our ex planta model (r = 0.67; p = 0.0003), supporting the utility of tiered screening approaches for candidate selection. Taken together, these findings establish a framework for the systematic identification and evaluation of phages targeting Psc, and support the development of phage-based interventions for managing plant diseases.

Pseudomonas syringae

Phyllosphere microbiomes in grassland plants harbor a vast reservoir of novel antimicrobial peptides and biosynthetic diversity.

INTRODUCTION: The phyllosphere microorganisms colonizing plant surface harbor capacities to synthesize diverse specialized metabolites that mediate communication and interactions with environment and host. However, most known metabolites are derived from a few culturable microorganisms, and the genomic diversity and biosynthetic potential of the vast majority of bacteria associated with plants remain largely unexplored. OBJECTIVES: Here, we aim to explore the genome architecture, biosynthetic ability, and host specific adaptability of grassland ecosystems, uncovering new perspectives on grassland phyllosphere microbial resources. METHODS: We employed ultra-deep metagenomic sequencing, functional analysis, host-associated characterization, and bioactivity assays to explore the phyllosphere microbiome across 221 grassland plant samples representing 45 families. This approach revealed host preference in biosynthetic gene clusters (BGCs) and validated the antimicrobial efficacy of phyllosphere-derived antimicrobial peptides (AMPs). RESULTS: Grassland plant phyllosphere microbiomes encode diverse BGCs. We identified 885,396 potential AMPs from over 68 million non-redundant gene sequences. Then, we reconstructed hundreds of near-complete genomes from phyllosphere metagenomes, and 32.61 % of reconstructed genomes were identified as unclassified genomes, primarily within Pseudomonadota, Actinomycetota, Bacillota and Bacteroidota phyla. Of the near-complete genomes, 91.97 % of the BGCs and 99.76 % of the identified AMPs were previously uncharacterized. Host phylogenetic analysis revealed functional divergence. Poaceae-associated Pseudomonas genomes contain an average of 28 BGCs, significantly higher than those in Asteraceae-associated genomes (mean = 14.76, P = 0.033). Similarly, Poaceae-associated Pantoea genomes carried an average of 9 BGCs, exhibiting significant enrichment compared to genomes from Asteraceae (mean = 7.13, P = 6.1e-05), Lamiaceae (mean = 7, P = 0.015), Ranunculaceae (mean = 8.22, P = 0.0053), and Rosaceae (mean = 7.75, P = 0.00069). ParaFit analyses further confirmed that host phylogeny significantly structures microbial functional repertoires, with intra-family hosts sharing more KEGG pathways than inter-family hosts. These results suggest that host evolutionary relationships are associated with metabolic specialization in phyllosphere microbiomes. All 13 AMPs synthesized via solid-phase peptide synthesis demonstrated antimicrobial activity, inhibiting the growth of at least one tested bacterial strain. CONCLUSION: This study demonstrates the promise of grassland plant phyllosphere microbiome as a rich source for novel antimicrobial agents.

Antimicrobial Peptides