Survival in acidic and alcoholic medium of Shiga toxin-producing Escherichia coli O157:H7 and non-O157:H7 isolated in Argentina

BACKGROUND: In spite of Argentina having one of the highest frequencies of haemolytic uraemic syndrome (HUS), the incidence of Escherichia coli O157:H7 is low in comparison to rates registered in the US. Isolation of several non-O157 shiga toxin-producing Escherichia coli (STEC) strains from cattle and foods suggests that E. coli O157:H7 is an uncommon serotype in Argentina. The present study was undertaken to compare the survival rates of selected non-O157 STEC strains under acidic and alcoholic stress conditions, using an E. coli O157:H7 strain as reference. RESULTS: Growth at 37°C of E. coli O26:H11, O88:H21, O91:H21, O111:H(-), O113:H21, O116:H21, O117:H7, O157:H7, O171:H2 and OX3:H21, was found to occur at pH higher than 4.0. When the strains were challenged to acid tolerance at pH as low as 2.5, viability extended beyond 8 h, but none of the bacteria, except E. coli O91:H21, could survive longer than 24 h, the autochthonous E. coli O91:H21 being the more resistant serotype. No survival was found after 24 h in Luria Bertani broth supplemented with 12% ethanol, but all these serotypes were shown to be very resistant to 6% ethanol. E. coli O91:H21 showed the highest resistance among serotypes tested. CONCLUSIONS: This information is relevant in food industry, which strongly relies on the acid or alcoholic conditions to inactivate pathogens. This study revealed that stress resistance of some STEC serotypes isolated in Argentina is higher than that for E. coli O157:H7

BeppoSAX observation of Hercules A and MRC 0625-536

We present BeppoSAX observations of the two FR I type radio galaxies Hercules A (3C 348) and MRC 0625-536 in the energy range $0.2 - 200$ keV. Data analysis shows that the X-ray flux from Hercules A is consistent with a diffuse thermal plasma emitting at $T \approx 4-5$ keV with a possible, but somewhat uncertain, contribution of a softer component at $T \approx 3$ keV. The non thermal emission from the active nucleus must be significantly smaller than the thermal one, and no indication of relevant core obscuration by a surrounding torus was detected. The flux from MRC 0625-536 originates form an extended region and has been fitted to a thermal law with $T \approx 5.7$ keV and with a column density consistent with the galactic absorption. A spatially resolved spectral analysis does not show a relevant variation of the temperature and the metallicity across the diffuse emission zone. A non thermal spectral component, related to the nuclear activity, may be present in the innermost region with some possible amount of local obscuration, contributing \lapp 10% to the total luminosity. Hard X-ray emission from MRC 0625-536 has been detected in the PDS (15 - 200 keV) that may be related either to its galactic core or to the intracluster region

Multifrequency Study of The Radio Galaxy NGC326

We present the results of a multi-frequency study of the inversion symmetric radio galaxy NGC326 based on Very Large Array observations at 1.4, 1.6, 4.8, 8.5 and 14.9 GHz. The morphological, spectral and polarization properties of this peculiar object are studied at different levels of spatial resolutions. The interpretation of the data will be discussed in forthcoming papers.Comment: 15 pages, 15 ps figures, accepted by A&

Serovar distribution of a DNA sequence involved in the antigenic relationship between Leptospira and equine cornea

BACKGROUND: Horses infected with Leptospira present several clinical disorders, one of them being recurrent uveitis. A common endpoint of equine recurrent uveitis is blindness. Serovar pomona has often been incriminated, although others have also been reported. An antigenic relationship between this bacterium and equine cornea has been described in previous studies. A leptospiral DNA fragment that encodes cross-reacting epitopes was previously cloned and expressed in Escherichia coli. RESULTS: A region of that DNA fragment was subcloned and sequenced. Samples of leptospiral DNA from several sources were analysed by PCR with two primer pairs designed to amplify that region. Reference strains from serovars canicola, icterohaemorrhagiae, pomona, pyrogenes, wolffi, bataviae, sentot, hebdomadis and hardjo rendered products of the expected sizes with both pairs of primers. The specific DNA region was also amplified from isolates from Argentina belonging to serogroups Canicola and Pomona. Both L. biflexa serovar patoc and L. borgpetersenii serovar tarassovi rendered a negative result. CONCLUSIONS: The DNA sequence related to the antigen mimicry with equine cornea was not exclusively found in serovar pomona as it was also detected in several strains of Leptospira belonging to different serovars. The results obtained with L. biflexa serovar patoc strain Patoc I and L. borgpetersenii serovar tarassovi strain Perepelicin suggest that this sequence is not present in these strains, which belong to different genomospecies than those which gave positive results. This is an interesting finding since L. biflexa comprises nonpathogenic strains and serovar tarassovi has not been associated clinically with equine uveitis

X-ray-emitting Atmospheres of B2 Radio Galaxies

We report ROSAT PSPC spatial and spectral analysis of the eight B2 radio galaxies NGC 315, NGC 326, 4C 35.03, B2 0326+39, NGC 2484, B2 1040+31, B2 1855+37, and 3C 449, expected to be representative of the class of low-power radio galaxies. Multiple X-ray components are present in each, and the gas components have a wide range of linear sizes and follow an extrapolation of the cluster X-ray luminosity/temperature correlation, implying that there is no relationship between the presence of a radio galaxy and the gas fraction of the environment. No large-scale cooling flows are found. There is no correlation of radio-galaxy size with the scale or density of the X-ray atmosphere. This suggests that it is processes on scales less than those of the overall gaseous environments which are the major influence on radio-source dynamics. The intergalactic medium is usually sufficient to confine the outer parts of the radio structures, in some cases even to within 5 kpc of the core. In the case of NGC 315, an extrapolation suggests that the pressure of the atmosphere may match the minimum pressure in the radio source over a factor of about 40 in linear size (a factor of about 1600 in pressure).Comment: 34 pages, including 10 figures, using aasms4.sty To appear in the Ap

Body odors (even when masked) make you more emotional: behavioral and neural insights

Morality evolved within specific social contexts that are argued to shape moral choices. In turn, moral choices are hypothesized to be affected by body odors as they powerfully convey socially-relevant information. We thus investigated the neural underpinnings of the possible body odors effect on the participants\u2019 decisions. In an fMRI study we presented to healthy individuals 64 moral dilemmas divided in incongruent (real) and congruent (fake) moral dilemmas, using different types of harm (intentional: instrumental dilemmas, or inadvertent: accidental dilemmas). Participants were required to choose deontological or utilitarian actions under the exposure to a neutral fragrance (masker) or body odors concealed by the same masker (masked body odor). Smelling the masked body odor while processing incongruent (not congruent) dilemmas activates the supramarginal gyrus, consistent with an increase in prosocial attitude. When processing accidental (not instrumental) dilemmas, smelling the masked body odor activates the angular gyrus, an area associated with the processing of people\u2019s presence, supporting the hypothesis that body odors enhance the saliency of the social context in moral scenarios. These results suggest that masked body odors can influence moral choices by increasing the emotional experience during the decision process, and further explain how sensory unconscious biases affect human behavior