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801.
Samuel J. Ellis Muhammad Yasir Douglas F. Browning Stephen J.W. Busby Stephanie Schüller 《Cellular microbiology》2019,21(6)
Enteroaggregative Escherichia coli (EAEC) are important intestinal pathogens causing acute and persistent diarrhoeal illness worldwide. Although many putative EAEC virulence factors have been identified, their association with pathogenesis remains unclear. As environmental cues can modulate bacterial virulence, we investigated the effect of oxygen and human intestinal epithelium on EAEC virulence gene expression to determine the involvement of respective gene products in intestinal colonisation and pathogenesis. Using in vitro organ culture of human intestinal biopsies, we established the colonic epithelium as the major colonisation site of EAEC strains 042 and 17‐2. We subsequently optimised a vertical diffusion chamber system with polarised T84 colon carcinoma cells for EAEC infection and showed that oxygen induced expression of the global regulator AggR, aggregative adherence fimbriae, E. coli common pilus, EAST‐1 toxin, and dispersin in EAEC strain 042 but not in 17‐2. Furthermore, the presence of T84 epithelia stimulated additional expression of the mucinase Pic and the toxins HlyE and Pet. This induction was dependent on physical host cell contact and did not require AggR. Overall, these findings suggest that EAEC virulence in the human gut is modulated by environmental signals including oxygen and the intestinal epithelium. 相似文献
802.
803.
B. J. Trask Heather Mefford Ger van den Engh Hillary F. Massa Ramesh C. Juyal Lorraine Potocki Brenda Finucane Dianne N. Abuelo David R. Witt Ellen Magenis Antonio Baldini Frank Greenberg James R. Lupski P. I. Patel 《Human genetics》1996,98(6):710-718
We have used bivariate flow karyotyping to quantify the deletions involving chromosome 17 in sixteen patients with Smith-Magenis
syndrome (SMS). The fluorescence intensities of mitotic chromosomes stained with Hoechst 33258 and chromomycin were quantified
in a dual-beam flow cytometer. For each patient, the position of the peak representing the deleted chromosome 17 was compared
to those of the normal homologs of an unaffected parent. The patients could be classified into four groups based on the size
of their deletions. The deletions ranged from ∼9–10 Mb (∼10–11% of the chromosome) to below the detection limit of the technique
(2 Mb). Different deletion sizes were detected among patients whose high-resolution banding results were similar. Some deletions
detected by banding were not detected by flow analyses. Deletion estimates are largely consistent with the results of molecular
analyses. Patients with larger deletions that extend into band 17p12 have abnormal electrophysiologic studies of peripheral
nerves. Deletion size does not appear to correlate with the degree of mental retardation, presence of behavioral abnormalities,
craniofacial anomalies or common skeletal findings in SMS. By identifying patients with varying deletion sizes, these data
will aid the construction of a long-range deletion-based map of 17p11.2 and identification of the genes involved in this syndrome.
Received: 19 March 1996 / Revised: 21 June 1996 相似文献