No abstract

No abstract

Phase variation through slippage-like mechanisms involving homopolymeric tracts depends in part on the absence of Dam-methylase in several pathogenic isolates of Neisseria meningitidis. In Dam-defective strains drg (dam-replacing gene), flanked by pseudo-transposable small repeated elements (SREs), replaced dam. We demonstrate that drg encodes a restriction endonuclease (NmeBII) that cleaves 5P P-GmeATC-3P P. drg is also present in 50% of Neisseria lactamica strains, but in most of them it is inactive because of the absence of an SRE-providing promoter. This is associated with the presence of GATmeC, suggesting an alternative restriction-modification system (RM) specific for 5P P-GATC-3P P, similar to Sau3AI-RM of Staphylococcus aureus 3A, Lactococcus lactis KR2 and Listeria monocytogenes. ß 2001 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.

SummaryMeningococcal gdhA , encoding the NADP-specific Lglutamate dehydrogenase (NADP-GDH), is essential for systemic infection in an infant rat model. In this paper, a limited transcriptional analysis detected differences in gdhA expression among clinical isolates. In strains expressing high levels of gdhA mRNA, two promoters, gdhA P1 and gdhA P2, initiated transcription of gdhA . In contrast, in strains expressing low mRNA levels, gdhA P2 was not active because of weak expression of gdhR , an associated regulatory gene. Gene knock-out and complementation of a gdhR -defective mutant confirmed that GdhR is a positive regulator for gdhA P2. Trans -activation of gdhA P2 was maximal in complex medium during late logarithmic growth phase and in chemical defined medium (MCDA) when glucose (MCDA-glucose) instead of lactate (MCDA-lactate) was used as a carbon source in the presence of glutamate. gdhR knockout mutants lost both growth phase and carbon source regulation, and exhibited a growth defect more severe in MCDA-glucose than in MCDA-lactate. DNAprotein interaction studies demonstrated that 2-oxoglutarate, a product of the catabolic reaction of the NADP-GDH and an intermediate of the tricarboxylic acid (TCA) cycle, inhibits binding of GdhR to gdhA P2.

Microarray analysis indicated several genes involved in immune response were differentially expressed in Bartonella-infected EPCs, whereas these genes returned in steady state when cells were exposed to sustained doses of L-arg. This mechanism may have broad therapeutic applications in tissue ischemia, angiogenesis, immune response, and sepsis.immune response ͉ sepsis

Summary The prognostic role of drug-induced amenorrhea (DIA) was restrospectively evaluated in 221 out of 254 consecutive premenopausal patients treated with adjuvant CMF or a CMF-containing regimen; 33 patients were eliminated because of lack of menstrual data. All patients had metastatic axillary nodes; drug regimens were: CMF x 9 courses ± Tamoxifen (TM) and CMF x 6 courses; median age was 43 (range 26-54

Aim To evaluate the antimicrobial activity of hydroalcoholic extracts of pomegranate (Punica granatum L.) peel and juice, against the microorganisms considered the main etiologic agents of dental caries. Methods The values of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were determined against Streptococcus mutans Clarke ATCC® 25175™ strain and Rothia dentocariosa clinical isolate. Results Peel extracts inhibit effectively the growth and survival of S. mutans ATCC 25175 strain and R. dentocariosa clinical isolate with MIC and MBC values of 10 μg/μl and 15 μg/μl, respectively. Furthermore, the pomegranate juice extract showed high inhibitory activity against S. mutans ATCC 25175 strain with a MIC value of 25 μg/μl and a MBC value of 40 μg/μl, whereas, against R. dentocariosa, it has displayed a moderate inhibitory activity, with MIC and MBC values of 20 μg/μl and 140 μg/μl, respectively. Conclusions In vitro microbiological tests demonstrate that the hydroalcoholic extracts of pomegranate juice and peel are able to contrast the main cariogenic bacteria involved in tooth decay. Although being preliminary data, our results suggest that pomegranate polyphenolic compounds could represent a good adjuvant for the prevention and treatment of dental caries.

Experimental animal models of bacterial meningitis are useful to study the host-pathogen interactions occurring at the cerebral level and to analyze the pathogenetic mechanisms behind this life-threatening disease. In this study, we have developed a mouse model of meningococcal meningitis based on the intracisternal inoculation of bacteria. Experiments were performed with mouse-passaged serogroup C Neisseria meningitidis. Survival and clinical parameters of infected mice and microbiological and histological analysis of the brain demonstrated the establishment of meningitis with features comparable to those of the disease in humans. When using low bacterial inocula, meningococcal replication in the brain was very efficient, with a 1,000-fold increase of viable counts in 18 h. Meningococci were also found in the blood, spleens, and livers of infected mice, and bacterial loads in different organs were dependent on the infectious dose. As glutamate uptake from the host has been implicated in meningococcal virulence, mice were infected intracisternally with an isogenic strain deficient in the ABC-type L-glutamate transporter GltT. Noticeably, the mutant was attenuated in virulence in mixed infections, indicating that wild-type bacteria outcompeted the GltT-deficient meningococci. The data show that the GltT transporter plays a role in meningitis and concomitant systemic infection, suggesting that meningococci may use L-glutamate as a nutrient source and as a precursor to synthesize the antioxidant glutathione.