Search results for "Muri"
showing 10 items of 289 documents
Chiral Inversion of 1-Hydroxyethylpyrene Enantiomers Mediated by Enantioselective Sulfotransferases
1998
The benzylic alcohol 1-hydroxyethylpyrene (1-HEP) is activated to a mutagen by sulfotransferases. The sulfuric acid ester formed is difficult to detect, as it is rapidly hydrolysed back to the alcohol. Incubation of the individual enantiomers of 1-HEP with human hydroxysteroid sulfotransferase (hHST) or estrogen sulfotransferase (hEST), expressed in bacteria, led to the formation of the other enantiomer. The rates of sulfation were determined from the initial rates of chiral inversion of the alcohol, knowing that hydrolysis follows an SN1 mechanism and therefore produces racemic alcohol. hEST showed high enantioselectivity for S-1-HEP, whereas hHST strongly preferred the R-enantiomer. The r…
The early immune response in the liver of BALB/c mice infected with S. typhimurium.
2000
Gram-negative bacteria acquired through gastrointestinal infection can be a serious cause for the development of septic shock especially in immunosuppressed patients. Thus, the aim of this study was to examine the early events of the immune reaction against S. typhimurium. Bacteria were injected into mice at different concentrations. Four animals from each group were killed at five different points of time. Liver cytokine mRNA expression was determined by semiquantitative rt-PCR and liver histology was examined. Serum cytokine levels of interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-4 and IL-10 were determined. intravenous (i.v.) infection with 109 bacteri…
Novel Glutamate–Putrescine Ligase Activity in Haloferax mediterranei: A New Function for glnA-2 Gene
2021
This article belongs to the Section Cellular Biochemistry.
Oral immunization with HCV-NS3-transformed Salmonella: induction of HCV-specific CTL in a transgenic mouse model.
2001
Abstract Background & Aims: The ability to induce cytotoxic T cells is considered an important feature of a candidate hepatitis C virus (HCV) vaccine. We used an oral immunization strategy with attenuated HCV-NS3–transformed Salmonella typhimurium to deliver DNA directly to the gut-associated lymphoid tissue. Methods: HLA-A2.1 transgenic mice were immunized once with transformed attenuated Salmonella . HCV-specific CD8 + T cells were analyzed in vitro as well as in vivo by challenge of mice with recombinant HCV-NS3 vaccinia virus. Results: Salmonella (10 8 colony-forming units; 20 μg plasmid DNA) induced cytotoxic and IFN-γ–producing CD8 + T cells specific for the immunodominant epitope NS3…
Enterobacteria-infected T cells as antigen-presenting cells for cytotoxic CD8 T cells: a contribution to the self-limitation of cellular immune react…
1997
In enterobacteria-induced reactive arthritis (ReA), different T cell subsets play a role in the induction and maintenance of the synovitic process. Synovial fluid-derived alphabeta CD4, alphabeta CD8, and gammadelta T lymphocyte clones (TLC) that recognize Yersinia or Salmonella antigens on professional antigen-presenting cells (APC) have been characterized, and T cells themselves can function as nonprofessional APC. T cells were infected with the facultatively intracellular, arthritogenic enterobacterium Yersinia enterocolitica O:3. A CD8 TLC isolated from a patient with Yersinia-induced ReA recognized and efficiently lysed autologous and allogeneic Yersinia-infected T cells. Infected cyto…
Synthesis, Absolute Configuration, and Bacterial Mutagenicity of the 8 Stereoisomeric Vicinal Diol Epoxides at the Terminal Benzo Ring of Carcinogeni…
2011
The synthesis of the 8 possible stereoisomeric diol epoxides (DEs) at the terminal benzo ring of carcinogenic dibenz[a,h]anthracene (DBA) is reported. trans-3,4-Dihydroxy-3,4-dihydro-DBA (1) afforded the 4 bay region DEs: the enantiomeric pairs of the anti diastereomers (+)-3/(-)-3 and of the syn diastereomers (-)-4/(+)-4, respectively. trans-1,2-Dihydroxy-1,2-dihydro-DBA (2) served as precursor of the 4 reverse DEs: the enantiomeric pairs of the anti diastereomers (+)-5/(-)-5 and of the syn diastereomers (-)-6/(+)-6, respectively. The transformation of the olefinic double bond in the enantiomeric trans-dihydrodiols to epoxides was achieved by either (i) oxidation with m-chloroperoxybenzoic…
Protective effect of adenylate deaminase (from Penicillium lanoso-viride) against acute infections in mice
1996
We examined the effects of the immunomodulator-adenylate deaminase (E.C. 3.5.4.6) from Penicillium lanoso-viride on experimental mice infections. Prophylactic intraperitoneal administration of adenylate deaminase (ADA) increased survival time and numbers of survivors after infection with Salmonella typhimurium, Pseudomonas aeruginosa and influenza A (H3N2) virus. Protection against influenza virus after intranasal ADA application was also observed. The influence of ADA was time and dose dependent. The most pronounced protection was obtained by administration of 3 U ADA/mice 24 h prior to infection. ADA had no antibiotic effect against these bacterial strains. Protective effects of ADA were …
Dual role of epoxide hydratase in both activation and inactivation of benzo(a)pyrene.
1977
The effect of epoxide hydratase upon the mutagenicity of benzo(a)pyrene was investigated using two Salmonella typhimurium strains (TA 1537 and TA 98). These two bacterial strains were found to differ characteristically in their susceptibility to different mutagens biologically produced from benzo(a)pyrene providing a diagnostic tool to investigate which types of mutagenic metabolites were produced in various metabolic situations. The results showed that the pattern of mutagenic metabolites produced by microsomes from methylcholanthrene-treated mice was very different from that produced by microsomes from phenobarbital-treated or untreated mice. However in all cases at least two mutagenic me…
Mechanism of genotoxicity and electron density distribution by NMR of 5-nitro-3-thiophenecarboxamides, a novel group of direct-acting mutagens in Sal…
1993
Abstract The mutagenic activity of 23 5-nitro-3-thiophenecarboxanilides and of 5-nitro-3-thiophenecarboxamide, the prototype, (NTCAs) have been evaluated in the Ames test on Salmonella typhimurium strains TA100 ad TA98 with and without metabolic activation. Effects of different substituents (electron-donating and electron-withdrawing) were studied to evaluate structural features that affect the metabolism and the bacterial mutagenic potency. All the derivatives were direct-acting mutagens, the mutagenic potency ranging from 0.7 to 142 revertants (rev.)/nmol in TA100 and from 0.09 to 68 rev./nmol in TA98 strain. Results obtained with strains TA98NR and TA98/1,8-DNP 6 indicated that the mutag…
Influence of nitroreductase and O-acetyltransferase on the mutagenicity of substituted nitrobenzothiophenamines in Salmonella typhimurium.
1999
The mutagenic activity of 17 substituted (aryl)(2-nitrobenzo[b]thiophen-3yl)amines has been evaluated in the Ames test with different isogenic strains of Salmonella typhimurium, that varied in their expression of nitroreductase and O-acetyltransferase. Active derivatives induced frameshift mutations in TA98 strain, and differences in the chemical structure resulted in up to 15-fold changes in mutagenic activity. The non-mutagenic compounds are the unsubstituted parent compound and derivatives with para-chloro, para-fluoro, para-diethylamino, meta-bromo and para-dimethylamino groups. They do not show any activity even in strains with higher level of nitroreductase or O-acetyltransferase. The…