Mechanism of the synergistic inactivation of Escherichia coli by UV-C light at mild temperatures

UV light only penetrates liquid food surfaces to a very short depth, thereby limiting its industrial application in food pasteurization. One promising alternative is the combination of UV light with mild heat (UV-H), which has been demonstrated to produce a synergistic bactericidal effect. The aim of this article is to elucidate the mechanism of synergistic cellular inactivation resulting from the simultaneous application of UV light and heat. The lethality of UV-H treatments remained constant below ~45ºC, while lethality increased exponentially as the temperature increased. The percentage of synergism reached a maximum (40.3%) at 55ºC. Neither the flow regimen nor changes in the dose delivered by UV lamps contributed to the observed synergism. UV-H inactivation curves of the parental Escherichia coli strain obtained in a caffeic acid selective recovery medium followed a similar profile to those obtained with uvrA mutant cells in a nonselective medium. Thermal fluidification of membranes and synergistic lethal effects started around 40 to 45ºC. Chemical membrane fluidification with benzyl alcohol decreased the UV resistance of the parental strain but not that of the uvrA mutant. These results suggest that the synergistic lethal effect of UV-H treatments is due to the inhibition of DNA excision repair resulting from the membrane fluidification caused by simultaneous heating

UV-Heat Treatments for the Control of Foodborne Microbial Pathogens in Chicken Broth

This investigation established the process criteria for using UV-C light and mild heat (UV-H treatment) to inactivate 5-Log10 cycles (performance criterion) of common foodborne pathogen populations, Escherichia coli, Salmonella Typhimurium, Listeria monocytogenes, and Staphylococcus aureus, when inoculated in chicken broth. To define the target microorganism and the proper UV-H treatment conditions (including UV dose, treatment time, and temperature) that would achieve the stated performance criterion, mathematical equations based on Geeraerd''s model were developed for each microorganism. For the sake of comparison, inactivation equations for heat treatments were also performed on the same chicken broth and for the same microorganisms. L. monocytogenes was the most UV-H resistant microorganism at all temperatures, requiring a UV dose between 6.10 J/mL (5.6 min) and 2.26 J/mL (2.09 min) to achieve 5-Log10 reductions. In comparison with UV treatments at room temperatures, the combination of UV and mild heat allowed both the UV dose and treatment time to be reduced by 30% and 63% at 55°C and 60°C, respectively. Compared to heat treatments, the UV-H process reduced the heating time for 5-Log10 reductions of all the investigated microorganisms in chicken broth from 20-fold to 2-fold when the operating temperature varied from 53 to 60°C

Effect of pressure-induced changes in the ionization equilibria of buffers on inactivation of Escherichia coli and staphylococcus aureus by high hydrostatic pressure

Survival rates of Escherichia coli and Staphylococcus aureus after high-pressure treatment in buffers that had large or small reaction volumes (¿V°), and which therefore underwent large or small changes in pH under pressure, were compared. At a low buffer concentration of 0.005 M, survival was, as expected, better in MOPS (morpholinepropanesulfonic acid), HEPES, and Tris, whose ¿V° values are approximately 5.0 to 7.0 cm3 mol-1, than in phosphate or dimethyl glutarate (DMG), whose ¿V° values are about -25 cm3 mol-1. However, at a concentration of 0.1 M, survival was unexpectedly better in phosphate and DMG than in MOPS, HEPES, or Tris. This was because the baroprotective effect of phosphate and DMG increased much more rapidly with increasing concentration than it did with MOPS, HEPES, or Tris. Further comparisons of survival in solutions of salts expected to cause large electrostriction effects (Na2SO4 and CaCl2) and those causing lower electrostriction (NaCl and KCl) were made. The salts with divalent ions were protective at much lower concentrations than salts with monovalent ions. Buffers and salts both protected against transient membrane disruption in E. coli, but the molar concentrations necessary for membrane protection were much lower for phosphate and Na2SO4 than for HEPES and NaCl. Possible protective mechanisms discussed include effects of electrolytes on water compressibility and kosmotropic and specific ion effects. The results of this systematic study will be of considerable practical significance in studies of pressure inactivation of microbes under defined conditions but also raise important fundamental questions regarding the mechanisms of baroprotection by ionic solutes

UV-Heat Treatments for the Control of Foodborne Microbial Pathogens in Chicken Broth

This investigation established the process criteria for using UV-C light and mild heat (UV-H treatment) to inactivate 5-Log10 cycles (performance criterion) of common foodborne pathogen populations, Escherichia coli, Salmonella Typhimurium, Listeria monocytogenes, and Staphylococcus aureus, when inoculated in chicken broth. To define the target microorganism and the proper UV-H treatment conditions (including UV dose, treatment time, and temperature) that would achieve the stated performance criterion, mathematical equations based on Geeraerd’s model were developed for each microorganism. For the sake of comparison, inactivation equations for heat treatments were also performed on the same chicken broth and for the same microorganisms. L. monocytogenes was the most UV-H resistant microorganism at all temperatures, requiring a UV dose between 6.10 J/mL (5.6 min) and 2.26 J/mL (2.09 min) to achieve 5-Log10 reductions. In comparison with UV treatments at room temperatures, the combination of UV and mild heat allowed both the UV dose and treatment time to be reduced by 30% and 63% at 55°C and 60°C, respectively. Compared to heat treatments, the UV-H process reduced the heating time for 5-Log10 reductions of all the investigated microorganisms in chicken broth from 20-fold to 2-fold when the operating temperature varied from 53 to 60°C

Selection of Process Conditions by Risk Assessment for Apple Juice Pasteurization by UV-Heat Treatments at Moderate Temperatures

The effect of bactericidal UV-C treatments (254 nm) on E. coli O157:H7 suspended in apple juice increased synergistically with temperature up to a threshold value. The optimum UV-C treatment temperature was 55 °C yielding a 58.9% synergistic lethal effect. Under these treatment conditions, the UV-heat (UV-H[subscript 55 °C]) lethal variability achieving 5 log reductions showed a logistic distribution (α = 37.92 and β = 1.10). Using this distribution, UV doses to achieve the required juice safety goal with 95, 99, and 99.9% of certainty were 41.17, 42.97, and 46.00 J/ml, respectively, higher than values estimated by a deterministic procedure (37.58 J/ml). When interpreting these results in terms of their public health impact, the larger UV-H[subscript 55 °C] dose required for achieving 5 log reductions with 95, 99, and 99.9% confidence would reduce the probability of HUS development in children by 76.3, 88.6, and 96.9%, respectively. This paper illustrates the importance of including the impact of data variability sources to achieve high food safety standards with the confidence level desired when selecting the operational parameters for novel and conventional preservation processes.Keywords: Risk assessment, Apple juice, E. coli O157:H7, UV-C, Combined processe

¿Dónde está el tronco coronario izquierdo?

La incidencia de anomalías coronarias es baja en la población general, oscilando entre el 0.46-1.55%, y la agenesia de tronco coronario izquierdo (TCI) es una de las menos observadas1, 2. Se trata de una entidad extremadamente rara en la que no existe el ostium coronario izquierdo y el TCI termina ciegamente3. De los casos publicados, el 50% afectan a la edad pediátrica, y entre ellos, el 30% se asocia a otras anomalías coronarias4. Puede aparecer aisladamente, como en los pacientes que aquí mostramos, o asociada a otras enfermedades, como la homocistinuria, la ataxia de Friedreich, el síndrome de Hurler, la progeria y el síndrome rubeólico5. Se presentan 2 casos clínicos representativos de esta enfermedad de baja prevalencia en la población general. El primer caso se trata de un varón de 59 años con hipercolesterolemia y extabaquismo como factores de riesgo cardiovascular. Es derivado a nuestro centro para la realización de una coronariografía por angina de esfuerzo, con ergometría clínicamente negativa y eléctricamente positiva con descenso del segmento ST de 2mm en el tercer estadio del protocolo de Bruce. El cateterismo muestra una agenesia del TCI con visualización de un vaso hipoplásico submilimétrico. La arteria descendente anterior se visualiza a través de la arteria coronaria anómala, que nace de la rama marginal aguda precoz desde el segmento proximal de la coronaria derecha (CD). El trayecto anómalo presenta efecto kinking y compresión sistólica. La circunfleja se visualiza a través de la arteria conal, con salida independiente en cañón de escopeta ligeramente craneal al ostium de la CD, con trayecto anómalo y efecto kinking sin evidente efecto milking. La CD es dominante, de gran calibre y sin estenosis angiográficamente significativas..

Genetic Covariance Structure of Reading, Intelligence and Memory in Children

This study investigates the genetic relationship among reading performance, IQ, verbal and visuospatial working memory (WM) and short-term memory (STM) in a sample of 112, 9-year-old twin pairs and their older siblings. The relationship between reading performance and the other traits was explained by a common genetic factor for reading performance, IQ, WM and STM and a genetic factor that only influenced reading performance and verbal memory. Genetic variation explained 83% of the variation in reading performance; most of this genetic variance was explained by variation in IQ and memory performance. We hypothesize, based on these results, that children with reading problems possibly can be divided into three groups: (1) children low in IQ and with reading problems; (2) children with average IQ but a STM deficit and with reading problems; (3) children with low IQ and STM deficits; this group may experience more reading problems than the other two

A colorectal cancer susceptibility new variant at 4q26 in the Spanish population identified by genome-wide association analysis

This work was partially supported by the CENIT program from the Centro Tecnológico Industrial (CEN-20091016), grants from the Spanish Institute of Health Carlos III (ADE10/00026, PI09/02444, PI12/00511, Acción Transversal de Cáncer) grants from the Fondo de Investigacion Sanitaria/FEDER (08/1276, 08/0024, PS09/02368, 11/00219, 11/00681), and by COST office through COST action BM1206. SCB is supported by contracts from the Fondo de Investigación Sanitaria (CP 03-0070). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Centro Tecnológico IndustrialInstituto de Salud Carlos IIIFondo de Investigación Sanitaria / FEDE

Mercury release and speciation in chemical looping combustion of coal

In the in situ Gasification Chemical Looping Combustion of coal (iG-CLC), the fuel is gasified in situ in the fuel reactor and gasification products are converted to CO2 and H2O by reaction with the oxygen carrier. This work is the first study on mercury release in Chemical Looping Combustion of coal. The fraction of the mercury in coal vaporized in the fuel reactor depended mainly on the fuel reactor temperature and the coal type. In the fuel reactor, mercury was mainly emitted as Hg0 in the gas phase and the amount increased with the temperature. In the air reactor, mercury was mostly emitted as Hg2+. In a real CLC system, mercury emissions to the atmosphere will decrease compared to conventional combustion as only mercury released in the air reactor will reach the atmosphere. However, measures should be taken to reduce Hg0 in the CO2 stream before the purification and compression steps in order to avoid operational problems.The authors thank the Government of Aragón and La Caixa (2012-GA-LC-076 project) and the Spanish Ministry for Science and Innovation (ENE2010-19550 project) for the financial support. P. Gayán thanks CSIC for the financial support of the project 201180E102. The authors also thank to Alcoa Europe-Alúmina Española S.A. for providing the Fe-enriched sand fraction used in this work. G. Galo is acknowledged for his contribution to the experimental results.Peer reviewe

Rapid haplotype inference for nuclear families

Hapi is a new dynamic programming algorithm that ignores uninformative states and state transitions in order to efficiently compute minimum-recombinant and maximum likelihood haplotypes. When applied to a dataset containing 103 families, Hapi performs 3.8 and 320 times faster than state-of-the-art algorithms. Because Hapi infers both minimum-recombinant and maximum likelihood haplotypes and applies to related individuals, the haplotypes it infers are highly accurate over extended genomic distances.National Institutes of Health (U.S.) (NIH grant 5-T90-DK070069)National Institutes of Health (U.S.) (Grant 5-P01-NS055923)National Science Foundation (U.S.) (Graduate Research Fellowship