The C(3P) + NH3 reaction in interstellar chemistry: II. Low temperature rate constants and modeling of NH, NH2 and NH3 abundances in dense interstellar clouds

A continuous supersonic flow reactor has been used to measure rate constants for the C + NH3 reaction over the temperature range 50 to 296 K. C atoms were created by the pulsed laser photolysis of CBr4. The kinetics of the title reaction were followed directly by vacuum ultra-violet laser induced fluorescence (VUV LIF) of C loss and through H formation. The experiments show unambiguously that the reaction is rapid at 296 K, becoming faster at lower temperatures, reaching a value of 1.8 10-10 cm3 molecule-1 s-1 at 50 K. As this reaction is not currently included in astrochemical networks, its influence on interstellar nitrogen hydride abundances is tested through a dense cloud model including gas-grain interactions. In particular, the effect of the ortho-to-para ratio of H2 which plays a crucial role in interstellar NH3 synthesis is examined

Glycerol induces reuterin production and decreases Escherichia coli population in an in vitro model of colonic fermentation with immobilized human feces

Lactobacillus reuteri ATCC 55730 is a probiotic strain that produces, in the presence of glycerol, reuterin, a broad-spectrum antimicrobial substance. This strain has been shown to prevent intestinal infections in vivo; however, its mechanisms of action, and more specifically whether reuterin production occurs within the intestinal tract, are not known. In this study, the effects of L. reuteri ATCC 55730 on intestinal microbiota and its capacity to secrete reuterin from glycerol in a novel in vitro colonic fermentation model were tested. Two reactors were inoculated with adult immobilized fecal microbiota and the effects of daily addition of L. reuteri into one of the reactors (c.108 CFU mL−1) without or with glycerol were tested on major bacterial populations and compared with addition of glycerol or reuterin alone. The addition of glycerol alone or with L. reuteri increased numbers of the Lactobacillus-Enterococcus group and decreased Escherichia coli. The addition of reuterin significantly and selectively decreased E. coli without affecting other bacterial populations. The observed decrease in E. coli concentration during the addition of glycerol (in presence or absence of L. reuteri) could be due to in situ reuterin production because 1,3-propanediol, a typical product of glycerol fermentation, was detected during the addition of glycero

Comparative study of a new quantitative real-time PCR targeting the xylulose-5-phosphate/fructose-6-phosphate phosphoketolase bifidobacterial gene (xfp) in faecal samples with two fluorescence in situ hybridization methods

The definitive version is available at ww3.interscience.wiley.comInternational audienceAims: To detect and enumerate bifidobacteria in faeces with a new quantitative multiplex real-time PCR (qPCR) method and to compare the results obtained with fluorescence in situ hybridization (FISH) methods. Methods and Results: A multiplex qPCR assay was developed, which enabled the enumeration of Bifidobacterium spp. by targeting the bifidobacterial xylulose- 5-phosphate ⁄ fructose-6-phosphate phosphoketolase gene (xfp) and total bacteria using universal Eub-primers targeting 16S rRNA gene from the domain bacteria. The qPCR assay showed high sensitivity and specificity and a low detection limit of about 2.5 x 10³ bifidobacterial cells per gram of faeces. The qPCR results were compared with FISH combined with microscopy or flow cytometry (FCM). No statistical differences among bifidobacterial counts averages measured in adult faeces with the three methods were observed. Total bacterial count averages were higher with the FISH method coupled with microscopic analyses compared to FISH with FCM, whereas total cell numbers estimated by qPCR were intermediate between the two FISH methods. Conclusions: The new qPCR assay was shown to be sensitive, rapid and accurate for enumerating bifidobacteria in faeces. Significance and Impact of the Study: This method is a valuable alternative for other molecular methods for detecting faecal bifidobacteria, especially when their counts are below the detection limit of the FISH methods

Inhibitory activity spectrum of reuterin produced by Lactobacillus reuteri against intestinal bacteria

<p>Abstract</p> <p>Background</p> <p>Reuterin produced from glycerol by <it>Lactobacillus reuteri</it>, a normal inhabitant of the human intestine, is a broad-spectrum antimicrobial agent. It has been postulated that reuterin could play a role in the probiotic effects of <it>Lb. reuteri</it>. Reuterin is active toward enteropathogens, yeasts, fungi, protozoa and viruses, but its effect on commensal intestinal bacteria is unknown. Moreover reuterin's mode of action has not yet been elucidated. Glutathione, a powerful antioxidant, which also plays a key role in detoxifying reactive aldehydes, protects certain bacteria from oxidative stress, and could also be implicated in resistance to reuterin.</p> <p>The aim of this work was to test the activity of reuterin against a representative panel of intestinal bacteria and to study a possible correlation between intracellular low molecular weight thiols (LMW-SH) such as glutathione, hydrogen peroxide and/or reuterin sensitivity. Reuterin was produced by <it>Lb</it>. <it>reuteri </it>SD2112 in pure glycerol solution, purified and used to test the minimal inhibitory (MIC) and minimal bactericidal concentrations (MBC). Hydrogen peroxide sensitivity and intracellular LMW-SH concentration were also analysed.</p> <p>Results</p> <p>Our data showed that most tested intestinal bacteria showed MIC below that for a sensitive indicator <it>Escherichia coli </it>(7.5–15 mM). Lactobacilli and <it>Clostridium clostridioforme </it>were more resistant with MIC ranging from 15 to 50 mM. No correlation between bacterial intracellular concentrations of LMW-SH, including glutathione, and reuterin or hydrogen peroxide sensitivities were found.</p> <p>Conclusion</p> <p>Our data showed that intestinal bacteria were very sensitive to reuterin and that their intracellular concentration of LMW-SH was not directly linked to their capacity to resist reuterin or hydrogen peroxide. This suggests that detoxification by LMW-SH such as glutathione is not a general mechanism and that other mechanisms are probably involved in bacterial tolerance to reuterin and hydrogene peroxide.</p

Exhibiting the undisguised. The reaches of the mobilizations of undocumented people in France

La cuestión de la participación política, en el espacio público francés, de los inmigrados cobra actualmente una gran relevancia, en el contexto de la crisis migratoria que atraviesa el conjunto del continente europeo. Frente a las interrogaciones que plantea esta situación, en torno a la capacidad de las sociedades a recibir y sumar a sus sociedades los que suelen ser considerados como su “excedente”, este artículo, basado sobre un trabajo de campo realizado entre 2007 y 2014, propone una reflexión acerca de la historia y los desafíos actuales de los movimientos sociales llevados a cabo por personas indocumentadas en Francia.The matter of political participation, in the French public space, of immigrants currently takes great relevance, in the context of the immigration crisis facing the European continent. Faced with the questions posed by this situation, about the capacity of societies to receive and add to their societies those who are often seen as their "surplus", this article, based on a fieldwork conducted between 2007 and 2014, proposes an investigation about the history and the current challenges of social movements carried out by undocumented people in France.Fil: Le Borgne de Boisriou, Valentine. Universidad de Buenos Aires. Facultad de Ciencias Sociales. Instituto de Investigaciones "Gino Germani"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Fuerza y fragilidad de los sujetos desidentificados. Reflexiones en torno a la subjetivación política

Este artículo presenta las conclusiones de una investigación acerca de las formas adoptadas por la subjetivación política cuando esta se expresa en movimientos sociales. Este trabajo requirió del uso de un doble campo disciplinar, de manera que recurre tanto a la filosofía política contemporánea, y particularmente al pensamiento de Jacques Rancière, como a autores del corpus de la sociología política, específicamente a un eje de trabajo formado en Argentina alrededor de las movilizaciones populares y territoriales. Entre 2009 y 2012, se realizaron investigaciones en el marco de un trabajo de campo acerca de una organización territorial del Gran Buenos Aires. El objetivo de esas investigaciones era elucidar los modos de movilización de personas precarizadas, a partir de su entrada en la organización y hasta las particularidades de su movilización.A partir de la cuestión de las relaciones de poder elaboradas por estos movimientos se elaboró, en el transcurso de la investigación, una reflexión en torno a las condiciones de producción de un cierto tipo de sujeto de la lucha, que en este artículo analizo en términos de subjetivación política. Por este motivo, presento la transcripción de uno de los relatos de vida más significativos obtenidos en el trabajo de campo, y lo artículo al propósito expuesto. Con este relato quiero explicitar la dimensión del desarraigo, o, en términos rancieranos, del desgarramiento que implica la irrupción de la política en una existencia. Al acercarme tan de cerca a la experiencia de la desidentificación como elemento fundamental de la subjetivación política, espero obtener una comprensión profunda de sus efectos en las existencias y, a su vez, de los efectos en la filosofía política de trabajos que dejen su lugar a las experiencias concretas, con toda la complejidad analítica que esto implica.This publication presents the results of a research project on forms of political subjectivity in social movements. Conducting this research required a double disciplinary field, calling on the one hand on contemporary political philosophy, particularly the thought of Jacques Rancière, and on the other authors of the corpus of political sociology, drawing specifically on an axis of research formed in Argentina on popular and territorial mobilizations. Between 2009 and 2012, I conducted a field research on the territorial organization of Gran Buenos Aires. The objective was to elucidate the modes of mobilization of people in precarious situations, starting from their entry into the organization to the particularities of their mobilization. Taking as a starting point the power relations produced by these movements, there arose, in the course of the investigation, a reflection on the conditions of production of a certain type of subject in the struggle. In this article I propose to analyze this reflection in terms of political subjectivation. In this sense, I will present one of the most significant life stories obtained during the field study. This story will be used to explain the dimension of uprooting that accompanies the irruption of politics in one’s existence. Taking thus the experience of disidentification as a fundamental element of political subjectivation, I hope to deepen the understanding of its existential effects as well as the effects in political philosophy as to the analytical complexity that a work on concrete experiences implies

RIPK1 protects from TNF-α-mediated liver damage during hepatitis

Cell death of hepatocytes is a prominent characteristic in the pathogenesis of liver disease, while hepatolysis is a starting point of inflammation in hepatitis and loss of hepatic function. However, the precise molecular mechanisms of hepatocyte cell death, the role of the cytokines of hepatic microenvironment and the involvement of intracellular kinases, remain unclear. Tumor necrosis factor alpha (TNF-alpha) is a key cytokine involved in cell death or survival pathways and the role of RIPK1 has been associated to the TNF-alpha-dependent signaling pathway. We took advantage of two different deficient mouse lines, the RIPK1 kinase dead knock-in mice (Ripk1K45A) and the conditional knockout mice lacking RIPK1 only in liver parenchymal cells (Ripk1LPC-KO), to characterize the role of RIPK1 and TNF-alpha in hepatitis induced by concanavalin A (ConA). Our results show that RIPK1 is dispensable for liver homeostasis under steady-state conditions but in contrast, RIPK1 kinase activity contributes to caspase-independent cell death induction following ConA injection and RIPK1 also serves as a scaffold, protecting hepatocytes from massive apoptotic cell death in this model. In the Ripk1LPC-KO mice challenged with ConA, TNF-alpha triggers apoptosis, responsible for the observed severe hepatitis. Mechanism potentially involves both TNF-independent canonical NF-kappa B activation, as well as TNF-dependent, but canonical NF-kappa B-independent mechanisms. In conclusion, our results suggest that RIPK1 kinase activity is a pertinent therapeutic target to protect liver against excessive cell death in liver diseases

Opportunities for topical antimicrobial therapy: permeation of canine skin by fusidic acid

BACKGROUND: Staphylococcal infection of the canine epidermis and hair follicle is amongst the commonest reasons for antimicrobial prescribing in small animal veterinary practice. Topical therapy with fusidic acid (FA) is an attractive alternative to systemic therapy based on low minimum inhibitory concentrations (MICs, commonly <0.03 mg/l) documented in canine pathogenic staphylococci, including strains of MRSA and MRSP (methicillin-resistant Staphylococcus aureus and S. pseudintermedius). However, permeation of canine skin by FA has not been evaluated in detail. This study aimed to define the degree and extent of FA permeation in canine skin in vitro from two sites with different hair follicle density following application of a licensed ophthalmic formulation that shares the same vehicle as an FA-betamethasone combination product approved for dermal application in dogs. Topical FA application was modelled using skin held in Franz-type diffusion cells. Concentrations of FA in surface swabs, receptor fluid, and transverse skin sections of defined anatomical depth were determined using high-performance liquid chromatography and ultraviolet (HPLC-UV) analysis. RESULTS: The majority of FA was recovered by surface swabs after 24 h, as expected (mean ± SEM: 76.0 ± 17.0%). FA was detected within 424/470 (90%) groups of serial sections of transversely cryotomed skin containing follicular infundibula, but never in 48/48 (100%) groups of sections containing only deeper follicular structures, nor in receptor fluid, suggesting that FA does not permeate beyond the infundibulum. The FA concentration (mean ± SEM) in the most superficial 240 μm of skin was 2000 ± 815 μg/g. CONCLUSIONS: Topically applied FA can greatly exceed MICs for canine pathogenic staphylococci at the most common sites of infection. Topical FA therapy should now be evaluated using available formulations in vivo as an alternative to systemic therapy for canine superficial bacterial folliculitis.Peer reviewedFinal Published versio