The cytochrome bd-I respiratory oxidase augments survival of multidrug-resistant Escherichia coli during infection

Nitric oxide (NO) is a toxic free radical produced by neutrophils and macrophages in response to infection. Uropathogenic Escherichia coli (UPEC) induces a variety of defence mechanisms in response to NO, including direct NO detoxification (Hmp, NorVW, NrfA), iron-sulphur cluster repair (YtfE), and the expression of the NO-tolerant cytochrome bd-I respiratory oxidase (CydAB). The current study quantifies the relative contribution of these systems to UPEC growth and survival during infection. Loss of the flavohemoglobin Hmp and cytochrome bd-I elicit the greatest sensitivity to NO-mediated growth inhibition, whereas all but the periplasmic nitrite reductase NrfA provide protection against neutrophil killing and promote survival within activated macrophages. Intriguingly, the cytochrome bd-I respiratory oxidase was the only system that augmented UPEC survival in a mouse model after 2 days, suggesting that maintaining aerobic respiration under conditions of nitrosative stress is a key factor for host colonisation. These findings suggest that while UPEC have acquired a host of specialized mechanisms to evade nitrosative stresses, the cytochrome bd-I respiratory oxidase is the main contributor to NO tolerance and host colonisation under microaerobic conditions. This respiratory complex is therefore of major importance for the accumulation of high bacterial loads during infection of the urinary tract

NO Dioxygenase Activity in Hemoglobins Is Ubiquitous In Vitro, but Limited by Reduction In Vivo

Genomics has produced hundreds of new hemoglobin sequences with examples in nearly every living organism. Structural and biochemical characterizations of many recombinant proteins reveal reactions, like oxygen binding and NO dioxygenation, that appear general to the hemoglobin superfamily regardless of whether they are related to physiological function. Despite considerable attention to “hexacoordinate” hemoglobins, which are found in nearly every plant and animal, no clear physiological role(s) has been assigned to them in any species. One popular and relevant hypothesis for their function is protection against NO. Here we have tested a comprehensive representation of hexacoordinate hemoglobins from plants (rice hemoglobin), animals (neuroglobin and cytoglobin), and bacteria (Synechocystis hemoglobin) for their abilities to scavenge NO compared to myoglobin. Our experiments include in vitro comparisons of NO dioxygenation, ferric NO binding, NO-induced reduction, NO scavenging with an artificial reduction system, and the ability to substitute for a known NO scavenger (flavohemoglobin) in E. coli. We conclude that none of these tests reveal any distinguishing predisposition toward a role in NO scavenging for the hxHbs, but that any hemoglobin could likely serve this role in the presence of a mechanism for heme iron re-reduction. Hence, future research to test the role of Hbs in NO scavenging would benefit more from the identification of cognate reductases than from in vitro analysis of NO and O2 binding

The Fukushima Daiichi Accident

The Fukushima Daiichi Accident consists of a Report by the IAEA Director General and five technical volumes. It is the result of an extensive international collaborative effort involving five working groups with about 180 experts from 42 Member States with and without nuclear power programmes and several international bodies. It provides a description of the accident and its causes, evolution and consequences, based on the evaluation of data and information from a large number of sources available at the time of writing. The set contains six printed parts and five supplementary CD-ROMs. Contents: Report by the Director General; Technical Volume 1/5, Description and Context of the Accident; Technical Volume 2/5, Safety Assessment; Technical Volume 3/5, Emergency Preparedness and Response; Technical Volume 4/5, Radiological Consequences; Technical Volume 5/5, Post-accident Recovery; Annexes. The JRC contributed to volumes 1,2 and 3, which are attached.JRC.F.5-Nuclear Reactor Safety Assessmen

[Study of immunoglobulins, proinflammatory cytokines, lymphoproliferation and phagocytosis in peripheral blood of healthy young people exposed to different levels of atmospheric pollution]

BACKGROUND: Urban environmental pollutants, resulting from the inadequate control in the industries and from the use of vehicles, still represent a great danger for millions of people all around the world. PATIENTS AND METHOD: We made a study in healthy young people without family history of atopy that lived in Guadalajara's downtown, as well as in another group of young people who lived in a rural area. According to the census of the year 2000, Guadalajara city has a population of 4 million habitants, and a vehicle number of about a million. The immunological parameters that we studied were: IgG, IgA and IgM immunoglobulins by nephelometry, serum levels of proinflammatory cytokines IL-6, IL-1alpha, IL1-beta and TNF-alpha by ELISAs test, and the phagocytic index in polymorphonuclears. The atmospheric parameters were: NO2, O3, SO2, CO and the suspended particles that were less than 10 micrometers (PM10). These parameters were obtained from a mobile unit found at the Instituto de Astronomia y Meteorologia de la Universidad de Guadalajara, and from an automatic station of environmental monitoring. RESULTS: It stands out the high concentrations of NO2 and PM10, which in several occasions were over the standards established by the WHO. IgG, IgA and IgM immunoglobulins were lower in the subjects living in the city that in those who lived in the rural area. Phagocytic index in polymorphonuclears, as well as IL-1alpha levels were higher in the city group, though we did not find a significant difference in the immunological parameters analyzed in the studied groups. CONCLUSION: Environmental pollution levels found at Guadalajara's downtown does not modify the immunological parameters studied in the peripheral blood of healthy young people. This shows that this group of population is less vulnerable than others to the exposition of moderate levels of urban air pollution

Study of immunoglobulins, proinflammatory cytokines, lymphoproliferation and phagocytosis in peripheral blood of healthy young people exposed to different levels of atmospheric pollution [Estudio de inmunoglobulinas, citocinas proinflamatorias, linfoproliferación y fagocitosis en sangre periférica de jóvenes sanos expuestos a diferentes niveles de contaminación atmosférica.]

BACKGROUND: Urban environmental pollutants, resulting from the inadequate control in the industries and from the use of vehicles, still represent a great danger for millions of people all around the world. PATIENTS AND METHOD: We made a study in healthy young people without family history of atopy that lived in Guadalajara's downtown, as well as in another group of young people who lived in a rural area. According to the census of the year 2000, Guadalajara city has a population of 4 million habitants, and a vehicle number of about a million. The immunological parameters that we studied were: IgG, IgA and IgM immunoglobulins by nephelometry, serum levels of proinflammatory cytokines IL-6, IL-1alpha, IL1-beta and TNF-alpha by ELISAs test, and the phagocytic index in polymorphonuclears. The atmospheric parameters were: NO2, O3, SO2, CO and the suspended particles that were less than 10 micrometers (PM10). These parameters were obtained from a mobile unit found at the Instituto de Astronomia y Meteorología de la Universidad de Guadalajara, and from an automatic station of environmental monitoring. RESULTS: It stands out the high concentrations of NO2 and PM10, which in several occasions were over the standards established by the WHO. IgG, IgA and IgM immunoglobulins were lower in the subjects living in the city that in those who lived in the rural area. Phagocytic index in polymorphonuclears, as well as IL-1alpha levels were higher in the city group, though we did not find a significant difference in the immunological parameters analyzed in the studied groups. CONCLUSION: Environmental pollution levels found at Guadalajara's downtown does not modify the immunological parameters studied in the peripheral blood of healthy young people. This shows that this group of population is less vulnerable than others to the exposition of moderate levels of urban air pollution