Mycobacterium tuberculosis complex DNA does not exist in atheromatous plaques

The possible potential role of several infectious agents in atherosclerosis has been shown. Several infectious agents DNA in atheromatous plaques have been displayed by PCR. In patients with atheromas antibody levels against Hsp65 were higher. Vaccination of mice with recombinant Hsp65 and Hsp65-rich M. tuberculosis resulted in formation of atheromatous plaques. We attempted to detect M. tuberculosis DNA in atherosclerotic plaque samples by PCR. In endarterectomy tissue samples obtained from patients during coronary artery bypass graft surgery DNA was prepared by proteinase-K digestion, phenol/chloroform extraction and ethanol precipitation. After amplification with M.tuberculosis complex IS6110 region specific primers, the products were analyzed on electrophoresis. M. tuberculosis DNA was negative in all tissue samples. More data on etiological studies with mycobacteriaceae will be yield information on atherosclerosis pathogenesis.     

Antimicrobial resistance of Salmonella spp. from pigs at slaughter in Spain in 1993 and 2001

AIM: To compare the incidence of antimicrobial resistance among Salmonella serotypes isolated in a pig slaughterhouse in Zaragoza (Spain) during 1993 and 2001. METHODS AND RESULTS: A total of 168 isolates representing 10 serotypes were examined by disc diffusion method using 17 antibiotics. Data showed that the majority of the strains were resistant to streptomycin (97%), sulfadiazine (93.4%) and tetracycline (83.3%). A large proportion of the collection was multidrug resistant (MDR, resistance to four or more antibiotics) with a greater incidence in 2001. The findings imply an increasing incidence of MDR amongst S. Typhimurium, and all S. Typhimurium-definitive phage type (DT) 104 isolates were resistant to ampicillin, chloramphenicol, streptomycin, sulphonamide and tetracycline (R-ACSSuT). This resistance phenotype had spread among other phage and serotypes. Salmonella Ohio was also a MDR serotype and this is not a serotype normally associated with drug resistance. CONCLUSIONS: A large proportion of the strains were MDR and this showed that pork products could be a potential vehicle of MDR Salmonella food-borne infections. SIGNIFICANCE AND IMPACT OF THE STUDY: The findings may have significant public health consequences and could contribute to the development of useful practices aimed at limiting the transmission of MDR Salmonella serotypes through the food chain.     

A follow up study of cytomegalovirus infection in a group of Turkish renal transplant recipients using molecular assays

The clinical value of an in-house cytomegalovirus nested polymerase chain reaction (CMV-PCR) and a commercial molecular assay hybrid capture CMV DNA assay (HCA) was evaluated in monitoring a group of renal transplant patients for six months follow up. In this study, the sensitivity, specificity, positive predictive value, and negative predictive value of nested CMV DNA PCR assay and HCA at the beginning of the study were 70, 42.9, 46.7, 66.7, and 60, 78.6, 66.7, and 73.3% respectively. After six months, they were 80, 66.7, 80, 66.7 for CMV PCR and 73.3, 88.9, 91.7, 66.7% for HCA respectively. These results indicate that in monitoring and predicting CMV infections in renal transplant recipients, not only qualitative but also quantitative assays must be used together in order to decide the preemptive strategies.     

Cell cycle-dependent phosphorylation of human DNA ligase I at the cyclin-dependent kinase sites

We have described previously that, during S-phase, human DNA ligase I is phosphorylated on Ser66, a casein kinase II site. Here we investigate the phosphorylation status of DNA ligase I during the cell cycle by gel shift analysis and electrospray mass spectrometry. We show that three residues (Ser51, Ser76, and Ser91), which are part of cyclin-dependent kinase sites, are phosphorylated in a cell cycle-dependent manner. Phosphorylation of Ser91 occurs at G1/S transition and depends on a cyclin binding site in the C-terminal part of the protein. This modification is required for the ensuing phosphorylation of Ser76 detectable in G2/M extracts. The substitution of serines at positions 51, 66, 76, and 91 with aspartic acid to mimic the phosphorylated enzyme hampers the association of DNA ligase I with the replication foci. We suggest that the phosphorylation of DNA ligase I and possibly other replicative enzymes is part of the mechanism that directs the disassembly of the replication machinery at the completion of S-phase.     

Induction of nitrate uptake in maize roots: expression of a putative high-affinity nitrate transporter and plasma membrane H+-ATPase isoforms

An investigation was carried out to assess the effect of nitrate supply on the root plasma membrane (PM) H+-ATPase of etiolated maize (Zea mays L.) seedlings grown in hydroponics. The treatment induced higher uptake rates of the anion and the expression of a putative high-affinity nitrate transporter gene (ZmNRT2.1), the first to be identified in maize. Root PM H+-ATPase activity displayed a similar time-course pattern as that of net nitrate uptake and investigations were carried out to determine which of the two isoforms reported to date in maize, MHA1 and 2, responded to the treatment. MHA1 was not expressed under the conditions analysed. Genome analysis revealed that MHA2, described as the most abundant form in all maize tissues, was not present in the maize hybrid investigated, but a similar form was found instead and named MHA3. A second gene (named MHA4) was also identified and partially sequenced. Both genes, classified as members of the PM H+-ATPase subfamily II, responded to nitrate supply, although to different degrees: MHA4, in particular, proved more sensitive than MHA3, with a greater up- and down-regulation in response to the treatment. Increased expression of subfamily II genes resulted in higher steady-state levels of the enzyme in the root tissues and enhanced ATP-hydrolysing activity. The results support the idea that greater proton-pumping activity is required when nitrate inflow increases and suggest that nitrate may be the signal triggering the expression of the two members of PM H+-ATPase subfamily II.     

Adult cardiac stem cells are multipotent and support myocardial regeneration

The notion of the adult heart as terminally differentiated organ without self-renewal potential has been undermined by the existence of a subpopulation of replicating myocytes in normal and pathological states. The origin and significance of these cells has remained obscure for lack of a proper biological context. We report the existence of Lin(-) c-kit(POS) cells with the properties of cardiac stem cells. They are self-renewing, clonogenic, and multipotent, giving rise to myocytes, smooth muscle, and endothelial cells. When injected into an ischemic heart, these cells or their clonal progeny reconstitute well-differentiated myocardium, formed by blood-carrying new vessels and myocytes with the characteristics of young cells, encompassing approximately 70% of the ventricle. Thus, the adult heart, like the brain, is mainly composed of terminally differentiated cells, but is not a terminally differentiated organ because it contains stem cells supporting its regeneration. The existence of these cells opens new opportunities for myocardial repair.     

Induction of human NK cell-mediated cytotoxicity by CD40 triggering on antigen presenting cells

Engagement of CD40 on antigen presenting cells (APC) is central to the initiation of cell-mediated immune response. Here, we investigated the ability of CD40 ligation on APC to induce NK cell-mediated cytotoxicity in the human system and the mechanism(s) underlying this process. We showed that APC (consisting in adherent peripheral blood mononuclear cells) (PBMC), pre-stimulated with anti-CD40 monoclonal antibodies and co-cultured with autologous non-adherent PBMC for 5-9 days, induced CD3-/CD56+ NK cell-mediated cytotoxicity as well as CD3+/CD56+ T cell-mediated unrestricted cytotoxic activity. The generation of NK cell-mediated cytotoxicity was independent on cell-to-cell contact between CD40-triggered APC and NK cells. Moreover, we found that IL-12 did not play a role in NK cells induction by anti-CD40 priming, while IL-2 and IL-15 did play a role. Our results provide an insight into the mechanism by which NK cells are activated in peripheral blood and useful informations for therapeutic application of anti-CD40 antibodies.