Sanitary effect of FE-DBD cold plasma in ambient air on sewage biosolids.

Sewage sludge is treated by means of cold plasma and stabilization in terms of biological load deactivation is achieved. The plasma is produced by floating electrode dielectric barrier discharge operating with air under atmospheric pressure conditions. The process is presented in detail and the discharge is characterized electrically. Additionally, simulation of the thermal flow inside the process chamber is implemented, using computational fluid dynamics. Deactivation of the serotypes S. Paratyphi B., S. Livingstone, S. Mbandaka and S. Typhimurium, and Escherichia coli and Coliforms, is hereby claimed. The process involves mean electrical power in the range of tens of watts, treatment time in the scale of minutes, and maximum instantaneous temperature <400 K. The present work is a preliminary contribution towards the promotion of advanced methods for the pro-ecological management of biosolids, according to European Regulations.

Regulatory T cells and antigen-specific tolerance.

Foxp3-expressing regulatory T cells (Tregs) have an essential function of preventing autoimmune disease in man and mouse. Foxp3 binds to forkhead motifs of about 1,100 genes and the strength of binding increases upon PMA/ionomycin stimulation. In Foxp3-expressing T-cell hybridomas, Foxp3 promoter binding does not lead to activation or suppression of genes which becomes only visible after T-cell activation. These findings are in line with observations by others that Foxp3 exerts important functions through association with Tcell receptor (TCR)-dependent transcription factors in a DNAbinding complex. Tregs can be generated when developing T cells encounter TCR agonist ligands in the thymus. This pro - cess requires costimulatory signals. In contrast, extra thymic conversion of naive T cells into Tregs is inhibited by costimulation. In fact, DC-derived retinoic acid (RA) helps the conversion process by counteracting the negative impact of costimulation. Since AP-1 is produced after costimulation and appears to interfere with Foxp3-NFAT transcription complexes, it is of interest to note that RA interferes with AP-1-dependent transcription. Thus, RA may interfere with the negative impact of costimulation on Treg conversion by interfering with the generation and/or function of AP-1.

The effect of short-time microwave exposures on Escherichia coli O157:H7 inoculated onto chicken meat portions and whole chickens.

Small portions of fresh chicken breasts weighting 20 g each and fresh whole chickens, weighting on average 1310 g each, were inoculated with Escherichia coli O157:H7 (10(5)-10(6) cfu/g) and cooked, using two different domestic microwave ovens at full power. The chicken portions were heated for 5, 10, 15, 20, 25, 30, and 35 s and the whole chickens for 22 min. Following exposures, viable counts and temperature measurements were performed. Although the chicken breast portions looked well-cooked after 30 s of MW heating at a mean end-point surface temperature of 69.8 degrees C, a mean concentration of 83 cfu/g E. coli O157:H7 cells was recovered. Elimination of E. coli O157:H7 cells occurred only after 35 s of MW exposure at 73.7 degrees C. When whole chickens were thoroughly cooked by MW heating, the final subsurface temperatures, measured in the thighs and wings, ranged from 60.2 degrees C to 92 degrees C and viable cells of E. coli O157:H7 were recovered from all samples of whole chicken. The results indicate that short time exposures of chicken portions to microwave heating do not eliminate E. coli O157:H7.

Isolation of a rare Escherichia coli O157:H7 strain from farm animals in Greece.

A strain of Escherichia coli O157:H7 was isolated from goat faeces during a surveillance study on the prevalence of this serotype of E. coli in farm animals in Greece. Three hundred and fifty one faecal samples were collected from goat, sheep and cattle breeding farms in the area of Epirus, Northwestern Greece. The E. coli O157:H7 isolate was nonsorbitol-fermenter, produced only VT2 and showed a beta-glucuronidase positive activity, a rather unusual biochemical feature for the E. coli O157:H7 serotype. No other strain of E. coli O157:H7 was isolated from the faecal samples of the rest farm animals examined, thus the overall prevalence of animal carriage was found to be 0.2%. The findings also indicate that goats can be a reservoir of E. coli O157:H7 and goat milk, dairy products and meat may serve as a vehicle for the pathogen transmission to humans.

Isolation of Escherichia coli O157:H7 from foods in Greece.

The presence of Escherichia coli O157:H7 in various foods of animal origin was surveyed in northwestern Greece. Six hundred samples of unpasteurized cows', ewes' and goats' milk, raw minced meat, uncooked frozen beef hamburgers, sandwiches (containing ham or turkey, mixed vegetable salad with mayonnaise and lettuce), fresh traditional Greek pork sausages and swine intestines appropriate for traditional Greek kokoretsi were assayed for E. coli serogroup O157:H7 using the standard cultural method and the immunomagnetic separation technique. The pathogen was detected in 1 out of 100 (1.0%) samples of ewes' milk, 1 out of 75 (1.3%) fresh sausages and 1 out of 50 (2.0%) swine intestines prepared for kokoretsi. The isolated strains were nonsorbitol fermenters, MUG-negative, O157 agglutinating, verotoxin-producing and carried both VT1 and VT2 genes. The three isolated strains were tested for antibiotic resistance and were found to be susceptible to eight antimicrobial agents (ampicillin, chloramphenicol, kanamycin, nalidixic acid, norfloxacin, streptomycin, sulfamethoxazole-trimethoprim and tetracycline).

A subset of NKT cells that lacks the NK1.1 marker, expresses CD1d molecules, and autopresents the alpha-galactosylceramide antigen.

In the present report, we characterize a novel T cell subset that shares with the NKT cell lineage both CD1d-restriction and high reactivity in vivo and in vitro to the alpha-galactosylceramide (alpha-GalCer) glycolipid. These cells preferentially use the canonical Valpha14-Jalpha281 TCR-alpha-chain and Vbeta8 TCR-beta segments, and are stimulated by alpha-GalCer in a CD1d-dependent fashion. However, in contrast to classical NKT cells, they lack the NK1.1 marker and express high surface levels of CD1d molecules. In addition, this NK1.1(-) CD1d(high) T subset, further referred to as CD1d(high) NKT cells, can be distinguished by its unique functional features. Although NK1.1(+) NKT cells require exogenous CD1d-presenting cells to make them responsive to alpha-GalCer, CD1d(high) NKT cells can engage their own surface CD1d in an autocrine and/or paracrine manner. Furthermore, in response to alpha-GalCer, CD1d(high) NKT cells produce high amounts of IL-4 and moderate amounts of IFN-gamma, a cytokine profile more consistent with a Th2-like phenotype rather than the Th0-like phenotype typical of NK1.1(+) NKT cells. Our work reveals a far greater level of complexity within the NKT cell population than previously recognized and provides the first evidence for T cells that can be activated upon TCR ligation by CD1d-restricted recognition of their ligand in the absence of conventional APCs.

Evidence for two subgroups of CD4-CD8- NKT cells with distinct TCR alpha beta repertoires and differential distribution in lymphoid tissues.

NKT cells are a subset of T lymphocytes that is mainly restricted by the nonclassical MHC class I molecule, CD1d, and that includes several subpopulations, in particular CD4+ and CD4-CD8- (DN) cells. In the mouse, differential distribution of these subpopulations as well as heterogeneity in the expression of various markers as a function of tissue localization have been reported. We have thus undertaken a detailed study of the DN NKT cell subpopulation. With a highly sensitive semiquantitative RT-PCR technique, its TCR repertoire was characterized in various tissues. We found that mouse DN NKT cells are a variable mixture of two subgroups, one bearing the invariant Valpha14 chain paired to rearranged Vbeta2, Vbeta7, Vbeta8.1, Vbeta8.2, or Vbeta8.3 beta-chains and the other exhibiting unskewed alpha- and beta-chains. The proportion of these subgroups varies from about 100:0 in thymus, 80:20 in liver, and 50:50 in spleen to 20:80% in bone marrow, respectively. Finally, further heterogeneity in the tissue-derived DN NKT cells was discovered by sequencing extensively Vbeta8.2-Jbeta2.5 rearrangements in individual mice. Despite a few recurrences in TCR sequences, we found that each population exhibits its own and broad TCRbeta diversity.

Murine natural killer T(NKT) cells [correction of natural killer cells] contribute to the granulomatous reaction caused by mycobacterial cell walls.

Mice injected with deproteinized cell walls prepared from the strain H37rv of Mycobacterium tuberculosis develop a granuloma-like lesion in which NKT cells are predominant. NKT cells play a primary role in the granulomatous response, because the latter does not occur in Jalpha281(-/-) mice, which miss NKT cells. The glycolipidic fraction of the cell walls is responsible for the recruitment of NKT cells; the recruiting activity is associated with fractions containing phosphatidylinositolmannosides. These results define a powerful experimental set up for studying the in vivo induction of NKT cell responses to microbial components.

T cell recognition of hapten. Anatomy of T cell receptor binding of a H-2kd-associated photoreactive peptide derivative.

To elucidate the structural basis of T cell recognition of hapten-modified antigenic peptides, we studied the interaction of the T1 T cell antigen receptor (TCR) with its ligand, the H-2Kd-bound Plasmodium berghei circumsporozoite peptide 252-260 (SYIPSAEKI) containing photoreactive 4-azidobenzoic acid (ABA) on P. berghei circumsporozoite Lys259. The photoaffinity-labeled TCR residue(s) were mapped as Tyr48 and/or Tyr50 of complementary determining region 2beta (CDR2beta). Other TCR-ligand contacts were identified by mutational analysis. Molecular modeling, based on crystallographic coordinates of closely related TCR and major histocompatibility complex I molecules, indicated that ABA binds strongly and specifically in a cavity between CDR3alpha and CDR2beta. We conclude that TCR expressing selective Vbeta and CDR3alpha sequences form a binding domain between CDR3alpha and CDR2beta that can accommodate nonpeptidic moieties conjugated at the C-terminal portion of peptides binding to major histocompatibility complex (MHC) encoded proteins.