Talk:Gastrointestinal Tract - Postnatal
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Cite this page: Hill, M.A. (2026, October 7) Embryology Gastrointestinal Tract - Postnatal. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Gastrointestinal_Tract_-_Postnatal |
2011
Necrotizing enterocolitis: An update
Semin Fetal Neonatal Med. 2011 Apr 20. [Epub ahead of print] Berman L, Moss RL. Source Department of Surgery, Yale University School of Medicine, 333 Cedar Street, FMB 132, New Haven, CT 06520-8062, USA.
Abstract
Necrotizing enterocolitis (NEC) is a leading cause of death among patients in the neonatal intensive care unit, carrying a mortality rate of 15-30%. Its pathogenesis is multifactorial and involves an overreactive response of the immune system to an insult. This leads to increased intestinal permeability, bacterial translocation, and sepsis. There are many inflammatory mediators involved in this process, but thus far none has been shown to be a suitable target for preventive or therapeutic measures. NEC usually occurs in the second week of life after the initiation of enteral feeds, and the diagnosis is made based on physical examination findings, laboratory studies, and abdominal radiographs. Neonates with NEC are followed with serial abdominal examinations and radiographs, and may require surgery or primary peritoneal drainage for perforation or necrosis. Many survivors are plagued with long term complications including short bowel syndrome, abnormal growth, and neurodevelopmental delay. Several evidence-based strategies exist that may decrease the incidence of NEC including promotion of human breast milk feeding, careful feeding advancement, and prophylactic probiotic administration in at-risk patients. Prevention is likely to have the greatest impact on decreasing mortality and morbidity related to NEC, as little progress has been made with regard to improving outcomes for neonates once the disease process is underway.
Copyright © 2011. Published by Elsevier Ltd.
PMID: 21514258 http://www.ncbi.nlm.nih.gov/pubmed/21514258
Gram negative bacteria are associated with the early stages of necrotizing enterocolitis
PLoS One. 2011 Mar 22;6(3):e18084.
Carlisle EM, Poroyko V, Caplan MS, Alverdy JA, Liu D. Source Department of Surgery, University of Chicago Medical Center, Chicago, Illinois, United States of America.
Abstract
INTRODUCTION: Necrotizing enterocolitis (NEC) affects 5-10% of infants born weighing less than 1500 g. Most models of NEC recapitulate late-stage disease with gut necrosis and elevated inflammatory mediators. Evaluation of NEC at earlier, less lethal stages of disease will allow investigation of initial disease triggers and may advance our understanding of temporal relationships between factors implicated in NEC pathogenesis. In this manuscript, we describe our investigation of early NEC and test the hypothesis that bacteria and inflammatory mediators differ between animals with early NEC and disease free animals.
METHODS: On DOL7 C3HeB/FeJ pups were fed liquid formula with 1×10(4)Streptococcus thoraltensis, Serratia marcescens, and Pseudomonas aeruginosa every 3 h. To initiate NEC, pups underwent asphyxia (100% N(2) for 90 s) and hypothermia (4°C for 10 min) after feeding. Pups were euthanized at 72 h. Intestines were collected for histologic NEC scoring and DNA/RNA extraction. Bacterial populations were identified by 16S rRNA pyrosequencing and principal component analysis (PCA). RNA isolates underwent QRT-PCR for Toll-like Receptor 4 (TLR4) and inducible nitric oxide synthase (iNOS).
RESULTS: Despite histologic, intestinal damage in mice with NEC, no gross necrosis was observed suggesting early disease. QRT-PCR yielded no difference between groups in TLR4 or iNOS mRNA levels. PCA demonstrated relative clustering of microbial communities based on presence or absence of NEC. 16S pyrosequencing demonstrated similar phyla between groups (Firmicutes and Proteobacteria predominated in all animals). However, the colonic microbiota of animals with NEC had more Citrobacter (p<0.01), Klebsiella (p<0.05), and Tatumella (p<0.05), while that of animals without NEC had more Streptococcus (p<0.01) and Enterococcus (p<0.01).
CONCLUSION: Citrobacter, Klebsiella, and Tatumella are associated with NEC. Differential colonic bacteria were identified despite the lack of inflammatory mediator elevation traditionally associated with NEC. This suggests a temporal relationship between bacteria and inflammatory mediators such that alterations in gut microbiota are associated with early NEC, while inflammatory mediator elevation is associated with advanced NEC.
PMID: 21445365 http://www.ncbi.nlm.nih.gov/pubmed/21445365
The mechanism of excessive intestinal inflammation in necrotizing enterocolitis: an immature innate immune response
PLoS One. 2011 Mar 21;6(3):e17776.
Nanthakumar N, Meng D, Goldstein AM, Zhu W, Lu L, Uauy R, Llanos A, Claud EC, Walker WA. Source Developmental Gastroenterology Laboratory, Harvard Medical School, Boston, Massachusetts, United States of America. Abstract Necrotizing enterocolitis (NEC) is a devastating neonatal intestinal inflammatory disease, occurring primarily in premature infants, causing significant morbidity and mortality. The pathogenesis of NEC is associated with an excessive inflammatory IL-8 response. In this study, we hypothesized that this excessive inflammatory response is related to an immature expression of innate immune response genes. To address this hypothesis, intestinal RNA expression analysis of innate immune response genes was performed after laser capture microdissection of resected ileal epithelium from fetuses, NEC patients and children and confirmed in ex vivo human intestinal xenografts. Changes in mRNA levels of toll-like receptors (TLR)-2 and -4, their signaling molecules and transcription factors (MyD88, TRAF-6 and NFκB1) and negative regulators (SIGIRR, IRAK-M, A-20 and TOLLIP) and the effector IL-8 were characterized by qRT-PCR. The expression of TLR2, TLR4, MyD88, TRAF-6, NFκB1 and IL-8 mRNA was increased while SIGIRR, IRAK-M, A-20 and TOLLIP mRNA were decreased in fetal vs. mature human enterocytes and further altered in NEC enterocytes. Similar changes in mRNA expression were observed in immature, but not mature, human intestinal xenografts. Confirmation of gene expression was also validated with selective protein measurements and with suggested evidence that immature TRL4 enterocyte surface expression was internalized in mature enterocytes. Cortisone, an intestinal maturation factor, treatment corrected the mRNA differences only in the immature intestinal xenograft. Using specific siRNA to attenuate expression of primary fetal enterocyte cultures, both TOLLIP and A-20 were confirmed to be important when knocked down by exhibiting the same excessive inflammatory response seen in the NEC intestine. We conclude that the excessive inflammatory response of the immature intestine, a hallmark of NEC, is due to a developmental immaturity in innate immune response genes.
PMID: 21445298 http://www.ncbi.nlm.nih.gov/pubmed/21445298
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0017776
Community analysis of bacteria colonizing intestinal tissue of neonates with necrotizing enterocolitis
BMC Microbiol. 2011 Apr 12;11(1):73. [Epub ahead of print]
Smith B, Bode S, Petersen BL, Jensen TK, Pipper C, Kloppenborg J, Boye M, Krogfelt KA, Molbak L.
ABSTRACT:
BACKGROUND: Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency in newborn neonates. Bacteria are believed to be important in the pathogenesis of NEC but bacterial characterization has only been done on human faecal samples and experimental animal studies. The aim of this study was to investigate the microbial composition and the relative number of bacteria in inflamed intestinal tissue surgically removed from neonates diagnosed with NEC (n=24). The bacterial populations in the specimens were characterized by laser capture microdissection and subsequent sequencing combined with fluorescent in situ hybridization (FISH), using bacterial rRNA-targeting oligonucleotide probes.
RESULTS: Bacteria were detected in 22 of the 24 specimens, 71% had moderate to high densities of bacteria. The phyla detected by 16S rRNA gene sequencing were: Proteobacteria (49.0%), Firmicutes (30.4%), Actinobacteria (17.1%) and Bacteroidetes (3.6%). A major detected class of the phylum Proteobacteria belonged to gamma-proteobacteria. Surprisingly, Clostridium species were only detected in 4 of the specimens by FISH, but two of these specimens exhibited histological pneumatosis intestinalis and both specimens had a moderate to a high density of C. butyricum and C. parputrificum detected by using species specific FISH probes. A 16S rRNA gene sequence tag similar to Ralstonia species was detected in most of the neonatal tissues and members of this genus have been reported to be opportunistic pathogens but their role in NEC has still to be clarified.
CONCLUSION: In this study, in situ identification and community analysis of bacteria found in tissue specimens from neonates with NEC, were analysed for the first time. Although a large variability of bacteria was found in most of the analyzed specimens, no single or combination of known potential pathogenic bacteria species was dominating the samples suggestive NEC as non-infectious syndrome. However there was a significant correlation between the presence of C. butyricum & C. parputrificum and histological pneumatosis intestinalis. Finally this study emphasizes the possibility to examine the microbial composition directly on excised human tissues to avoid biases from faecal samples or culturing.
PMID: 21486476 http://www.ncbi.nlm.nih.gov/pubmed/21486476
http://www.biomedcentral.com/1471-2180/11/73
2010
Milk epidermal growth factor and gut protection
J Pediatr. 2010 Feb;156(2 Suppl):S31-5.
Dvorak B. Source Department of Pediatrics, University of Arizona, Tucson, AZ, USA. dvorakb@peds.arizona.edu
Abstract
Maternal milk is a complex fluid, with multifunctional roles within the developing gastrointestinal tract. Epidermal growth factor (EGF) and heparin-binding EGF-like growth factor (HB-EGF) are members of the family of EGF-related peptides. Biological actions of these growth factors are mediated via interaction with the EGF-receptor (EGF-R). In the early postnatal period, breast milk is the major source of EGF for the developing intestinal mucosa. HB-EGF is also detected in breast milk, but in concentrations 2 to 3 times lower than EGF. With normal physiological conditions, the intestinal epithelium undergoes a continuing process of cell proliferation, differentiation, and maturation. EGF plays an important role in these processes. In pathophysiologic situations, EGF contributes to epithelial protection from injury and post-injury mucosal repair. Necrotizing enterocolitis (NEC) is a devastating disease affecting infants born prematurely. The pathogenesis of NEC is not known, and there is no effective treatment for this disease. In an experimental NEC model, oral administration of a physiological dose of EGF significantly reduces the incidence and severity of NEC. HB-EGF provides similar protection against NEC, but only when pharmacological doses are used. Further studies are necessary before EGF can be introduced as an efficient therapeutic approach of intestinal injury.
Copyright 2010 Mosby, Inc. All rights reserved.
PMID: 20105663 http://www.ncbi.nlm.nih.gov/pubmed/20105663
2004
Intestinal epithelial apoptosis initiates gross bowel necrosis in an experimental rat model of neonatal necrotizing enterocolitis
Pediatr Res. 2004 Apr;55(4):622-9. Epub 2004 Feb 5.
Jilling T, Lu J, Jackson M, Caplan MS. Source Department of Pediatrics, Evanston Northwestern Healthcare Research Institute, and Northwestern University, Feinberg School of Medicine, Evanston, IL 60201, USA. tjilling@northwestern.edu
Abstract
The histopathology of necrotizing enterocolitis (NEC) is characterized by destruction of the mucosal layer in initial stages and by transmural necrosis of the intestinal wall in advanced stages of the disease. To test the hypothesis that enhanced epithelial apoptosis is an initial event underlying the gross histologic changes, we analyzed epithelial apoptosis and tissue morphology in an animal model of NEC and evaluated the effect of caspase inhibition on the incidence of experimental NEC in this model. Apoptosis was analyzed with terminal deoxynucleotidyltransferase-mediated dUTP-FITC nick end labeling (TUNEL) staining in intestinal sections and by measuring caspase 3 activity from intestinal lysates of neonatal rats subjected to formula feeding and cold/asphyxia stress (FFCAS) and from mother-fed (MF) controls. Morphologic evaluation was based on hematoxylin and eosin staining of intestinal sections. FFCAS resulted in histologic changes consistent with NEC, which were absent from MF animals. FFCAS was also associated with a significantly increased rate of nuclear DNA fragmentation in the small intestinal epithelium compared with MF. Elevated tissue caspase 3 activity confirmed the presence of apoptosis in samples with increased DNA fragmentation. Analysis of the coincidence of morphologic damage and apoptosis in corresponding tissue sections indicated that apoptosis precedes gross morphologic changes in this model. Furthermore, supplementation of formula with 8 boc-aspartyl(OMe)-fluoromethylketone, a pan-caspase inhibitor, significantly reduced the incidences of apoptosis and experimental NEC. These findings indicate that in neonatal rats FFCAS induces epithelial apoptosis that serves as an underlying cause for subsequent gross tissue necrosis.
PMID: 14764921 http://www.ncbi.nlm.nih.gov/pubmed/14764921
1990
Meconium aspiration syndrome: have we made a difference?
Pediatrics. 1990 May;85(5):715-21.
Wiswell TE, Tuggle JM, Turner BS. Source Department of Pediatrics, Walter Reed Army Medical Center, Washington, DC 20307-5001. Abstract Meconium aspiration syndrome (MAS) and its associated complications are reviewed from the period before the routine use of intubation and suctioning to the present (1973 through 1987). Of the 176,790 neonates born during this period, the amniotic fluid was stained in 21,472 (12.15%). Subsequently, MAS developed in 1162 (5.41%) of the meconium-stained neonates. Male neonates were more prone to the disorder than female neonates (P = .022). There were no racial predilections for MAS. The incidence of MAS significantly decreased during the 15 years (P = .043). Of the neonates with MAS, 49 (4.22%) died as a direct consequence of the disorder. The death rate significantly declined during the study period (P = .041). Of the neonates with MAS, 345 (29.7%) required mechanical ventilation, and 134 (11.53%) had pneumothoraxes. Among neonates with MAS, the requirement for mechanical ventilation, as well as the incidence of pneumothoraxes, did not decrease from 1973 through 1987. The incidence of MAS has declined since the advent of combined obstetric and pediatric suctioning of the oropharynx and trachea. Furthermore, there are significantly fewer deaths from the disorder. These declines were likely influenced by other improvements in perinatal care, which have occurred since the early 1970s. The results do not support the contention that severe MAS and resultant deaths can be prevented altogether.
Comment in Pediatrics. 1990 Dec;86(6):1007-8. Pediatrics. 1991 Feb;87(2):269.
PMID: 2330231
