Bstrate was varied over a 500-fold range, from 2 M to 1,000 M. Figure 4A shows that no inhibition of EPEC development was observed with XO plus adenosine or XO plus inosine, but development was inhibited within the presence of hypoxanthine (see Fig. 1). Figure 4B compares the susceptibilities of 3 E. coli strains to growth inhibition by XO plus hypoxanthine. Growth ofstx2. Though asterisks are omitted, in every case, the XO activity was substantially larger in the infected loop than in the uninfected loop fluid. In five of 6 circumstances, the uninfected loop fluid XO activity was a unfavorable number, i.e., uric acid was not generated but as an alternative disappeared in the uninfected loop fluids during the assay, presumably as a consequence of uricase activity.iai.asm.orgInfection and ImmunityXanthine Oxidase, EPEC, and STECFIG four Effects of xanthine oxidase and hypoxanthine on bacterial growth and on Stx production in STEC. (A to C) Graphs of bacterial development, measured as ODvalues, in response to XO and various concentrations of hypoxanthine or other nucleosides. The x axis in panels A to C would be the logarithm with the nucleoside or purine concentration, in moles/liter (M). (A) Growth inhibition inside the presence of XO plus hypoxanthine, but not XO plus other nucleosides, on EPEC E2348/69. (B) Comparison of the susceptibilities of 3 strains of E. coli to growth inhibition by many concentrations of hypoxanthine within the presence of a fixed concentration of XO, 1 U/ml. (C) Inhibition of development beneath anaerobic circumstances in thioglycolate medium for three bacterial strains. (D to F) Impact of XO with or with no hypoxanthine on Stx production from human STEC strain Popeye-1 (O157:H7, Stx2 only). (D) Even though asterisks are omitted, Stx inside the supernatant medium was considerably greater inside the presence of XO than in its absence for all 3 concentrations of hypoxanthine tested. (E) Reversal of Stx induction by H2O2neutralizing agents. A total of 1 U/ml XO and 400 M hypoxanthine had been utilized. Catalase (added to a final concentration of 600 U/ml) and glutathione (final concentration of five mM) reversed the inducing effect of hypoxanthine plus XO. *, drastically less Stx than with hypoxanthine plus XO. (F) Effect of varying the amount of XO in the presence of a fixed concentration of hypoxanthine. *, important in comparison to the no-hypoxanthine control for every level of XO.1220039-63-3 Chemscene hypo, hypoxanthine.2,2,6,6-Tetramethylmorpholine Chemical name the laboratory E.PMID:23453497 coli strain DH5 was inhibited having a 50 inhibitory concentration (IC50) of four M hypoxanthine, even though EPEC strains B171-8 and E2348/69 showed hypoxanthine IC50s of 50 and 400 M, respectively. In other words, EPEC E2348/69 was 100 times much more resistant to growth inhibition than strain DH5 within this assay. The laboratory E. coli strain HB101 behaved like DH5 , and STEC strains EDL933 and Popeye-1 behaved like E2348/69 within this assay (data not shown). Complete inhibition of growth in this assay was accompanied by sterilization in the culture, i.e., no regrowth was observed when contents of inhibited wells have been subcultured on fresh medium.EPEC infection in vivo is heaviest within the ileum and cecum, and STEC most heavily infects the cecum and colon. Because the cecum and colon are anaerobic environments, we tested the potential of XO plus hypoxanthine to inhibit the growth on the representative anaerobes Bacteroides fragilis and Bacteroides thetaiotaomicron. Figure 4C shows the outcomes of these growth experiments, carried out in thioglycolate medium beneath anaerobic circumstances. Below these conditions, no development inhibit.
