Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.48 (transcriptase)
 9,479 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The purpose of this study was to investigate whether anisodamine could inhibit Shiga toxin-1 (Stx1)-induced cytokine production and increase the survival of Stx1-treated mice. Human monocytic cells were stimulated by Stx1 (1 to 100 ng/mL) with or without anisodamine addition (1 to 400 microg/mL). For in vivo evaluations, C57BL/6 mice were given a single intraperitoneal injection of anisodamine (1 mg) or saline solution after intraperitoneal injection of Stx1 (2.75 microg/kg). The results showed that anisodamine significantly suppressed Stx1-induced tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and IL-8 production. Reverse transcriptase-polymerase chain reaction (RT-PCR) showed that anisodamine suppressed Stx1-mediated TNF-alpha mRNA expression. Further study showed that this TNF-alpha inhibitory effect was via a prostaglandin E2-dependent mechanism. Anisodamine treatment prolonged the survival time of mice and decreased the lethality of Stx1 (94.5% to 44%). Because cytokines, in particular TNF-alpha, contribute to the pathologic process in Stx-producing Escherichia coli (STEC) infection, this study suggested that anisodamine could be a potential drug for treatment of STEC infection.
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PMID:Protective effect of anisodamine against Shiga toxin-1: inhibition of cytokine production and increase in the survival of mice. 1117 65

Strains of Escherichia coli causing enterohemorrhagic colitis belonging to the O157:H7 lineage are reported to be highly related. Fifteen strains of E. coli O157:H7 and 1 strain of E. coli O46:H(-) (nonflagellated) were examined for the presence of potassium tellurite resistance (Te(r)). Te(r) genes comprising terABCDEF were shown previously to be part of a pathogenicity island also containing integrase, phage, and urease genes. PCR analysis, both conventional and light cycler based, demonstrated that about one-half of the Te(r) E. coli O157:H7 strains (6 of 15), including the Sakai strain, which has been sequenced, carried a single copy of the Te(r) genes. Five of the strains, including EDL933, which has also been sequenced, contained two copies. Three other O157:H7 strains and the O46:H(-) strain did not contain the Te(r) genes. In strains containing two copies, the Te(r) genes were associated with the serW and serX tRNA genes. Five O157:H7 strains resembled the O157 Sakai strain whose sequence contained one copy, close to serX, whereas in one isolate the single copy was associated with serW. There was no correlation between Te(r) and the ability to produce Shiga toxin ST1 or ST2. The Te(r) MIC for most strains, containing either one or two copies, was 1,024 micro g/ml, although for a few the MIC was intermediate, 64 to 128 micro g/ml, which could be increased to 512 micro g/ml by pregrowth of strains in subinhibitory concentrations of potassium tellurite. Reverse transcriptase PCR analysis confirmed that in most strains Te(r) was constitutive but that in the rest it was inducible and involved induction of terB and terC genes. Only the terB, -C, -D, and -E genes are required for Te(r). The considerable degree of homology between the ter genes on IncH12 plasmid R478, which originated in Serratia marcescens, and pTE53, from an E. coli clinical isolate, suggests that the pathogenicity island was acquired from a plasmid. This work demonstrates diversity among E. coli O157:H7 isolates, at least as far as the presence of Te(r) genes is concerned.
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PMID:Genomic variability of O islands encoding tellurite resistance in enterohemorrhagic Escherichia coli O157:H7 isolates. 1216 92

In order to study the effects of the fermentation-drying procedure and subsequent in vitro digestion on Shiga toxins (Stx) production by Escherichia coli O157:H7, dry sausages were inoculated during the formulation step with pure cultures of strains 5-1 and ATCC 43895. The inoculated sausages were submitted to a minimum (30 min, pH between 3.1 and 3.5) or a maximum (120 min at stepwise adjusting the pH downward) gastric challenge followed by a 240-min pancreatic challenge at pH 8.0 and 37 degrees C. Production of toxins by the overnight culture controls, assessed using the Vero cell assay, was dependent on the pathogen cell concentration. The effect of cell concentration was not relevant in sausage samples and data showed: (a) higher Stx production in contaminated sausage samples than in overnight cultures; (b) the lowest Stx levels were detected with undigested sausage samples; (c) the maximum gastric challenge enhanced Stx production, compared to minimally digested and undigested samples. Reverse transcriptase polymerase chain reaction (RT-PCR) performed on extracts from inoculated, digested (4.5-6 h process) and undigested sausages produced amplicons for both stx1 and stx2 mRNA, suggesting that post-stress expression of stx genes had occurred. Our data suggest that sub-lethal stresses imposed by the fermentation-drying procedure and subsequent digestion of ingested food (i.e. contaminated sausages) may affect the degree to which the surviving E. coli O157:H7 cells express their virulence in vivo.
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PMID:Shiga toxin production by sausage-borne Escherichia coli O157:H7 in response to a post-processing in vitro digestion challenge. 1694 9

Shiga toxin (Stx) 1 binds to the glycosphingolipid (GSL) globotriaosylceramide (Gb3Cer/CD77) and injures human endothelial cells. In order to gain insight into Stx1-induced cellular impairment, we analysed in detail the molecular heterogeneity of Stx1 receptors in two endothelial cell lines differing in their Stx1-sensitivity. We observed a moderate sensitivity to Stx1 of human brain microvascular endothelial cells (HBMECs, CD(50) > 200 ng/ml), but a considerably higher mortality rate in cultures of EA.hy 926 cells, a cell line derived from human umbilical vein endothelial cells (CD(50) of 0.2 ng/ml). Immunofluorescence microscopy demonstrated the presence of Gb3Cer in both cell lines, but showed an enhanced content of Gb3Cer in EA.hy 926 cells. Solid phase overlay binding assays of isolated GSLs combined with nanoelectrospray ionization quadrupole time-of-flight mass spectrometry demonstrated a balanced proportion of Gb3Cer and globotetraosylceramide (Gb4Cer) in HBMECs, but an increase of Gb3Cer and absence of Gb4Cer in EA.hy 926 cells. Gb3Cer species with C24:1/C24:0 fatty acids were found to dominate over those with C16:0 fatty acids in EA.hy 926 cells, but were similarly distributed in HBMECs. Reverse transcriptase polymerase chain reaction indicated the concomitant presence of Gb3Cer and Gb4Cer synthases in HBMECs, whereas EA.hy 926 cells expressed Gb3Cer synthase, but completely lacked Gb4Cer synthase. This deficiency, resulting in the accumulation of Gb3Cer in EA.hy 926 cells, represents the most prominent molecular reason that underlies the different Stx1 sensitivities of HBMECs and EA.hy 926 endothelial cells.
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PMID:Glycosphingolipids in vascular endothelial cells: relationship of heterogeneity in Gb3Cer/CD77 receptor expression with differential Shiga toxin 1 cytotoxicity. 1817 41

Different structures related to biofilm formation by Shiga toxin-producing Escherichia coli (STEC), particularly O157 strains, have been described, but there are few data regarding their involvement in non-O157 strains. The aim of this study was to determine the ability of 14 O157 and 8 non-O157 strains isolated from bovine hide and carcass to interact with biotic and abiotic surfaces and also to evaluate the role of different adhesins. Biofilm formation assays showed that four O157 and two non-O157 strains were able to adhere to glass, and that only one O157 strain adhered to polystyrene. Reverse transcriptase-polymerase chain reaction was carried out using biofilm-forming strains to determine the expression of antigen 43 (Ag43), curli, type 1 fimbriae, STEC autotransporter contributing to biofilm formation (Sab), calcium-binding antigen 43 homologue (Cah), and autotransporter protein of enterohemorrhagic E. coli (EhaA). Most of these structures were expressed under biofilm conditions. However, the lack of Ag43 in one non-O157 strain, as well as Cah and EhaA in two O157 strains, suggests that other adhesins are involved in biofilm formation in these strains. Despite the fact that adherence to HeLa cells was detected in 20 strains (91%), it was not possible to correlate biofilm formation with adherence patterns. Invasiveness in T84 and Caco-2 cells was observed in four and three O157 strains, respectively. Altogether, we showed that there are different sets of genes involved in the interactions of STEC with biotic and abiotic surfaces. Interestingly, one O157 strain that was able to form biofilm on both glass and polystyrene also adhered to and invaded human cells, indicating an important route for its persistence in the environment and interaction with the host. Additionally, the ability of non-O157 strains not carrying the LEE pathogenicity island to form biofilm highlights an industrial and health problem that cannot be neglected.
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PMID:Interactions of O157 and non-O157 Shiga toxin-producing Escherichia coli (STEC) recovered from bovine hide and carcass with human cells and abiotic surfaces. 2431 85

To provide data for traditional trace-back studies from fork to farm, it is necessary to determine the environmental sources for Shiga-toxigenic Escherichia coli. We developed SYBR green based reverse-transcriptase PCR methods to determine the prevalence of F+ RNA coliphages (FRNA) as indicators of fecal contamination. Male-specific coliphages, determined using a single-agar overlay method, were prevalent in all surface waters sampled for 8 months. F+ DNA coliphages (FDNA) were predominant compared to FRNA in water samples from majority of sampling locations. Most (90%) of the FRNA were sourced to humans and originated from human-impacted sites. Members of genogroup III represented 77% of FRNA originated from human sources. Furthermore, 93% of FRNA sourced to animals were also detected in water samples from human-impacted sites. Eighty percent of all FRNA were isolated during the winter months indicating seasonality in prevalence. In contrast, FDNA were more prevalent during summer months. E. coli O157:H7 and Shiga-toxigenic E. coli were detected in water samples from locations predominantly influenced by agriculture. Owing to their scarcity, their numbers could not be correlated with the prevalence of FRNA or FDNA in water samples. Both coliform bacteria and generic E. coli from agricultural or human-impacted sites were similar in numbers and thus could not be used to determine the sources of fecal contamination. Data on the prevalence of male-specific coliphages may be invaluable for predicting the sources of fecal contamination and aid in developing methods to prevent enteric pathogen contamination from likely sources during produce production.
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PMID:Male-specific coliphages for source tracking fecal contamination in surface waters and prevalence of Shiga-toxigenic Escherichia coli in a major produce production region of the Central Coast of California. 2601 96