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In order to survive and replicate, Salmonella has evolved mechanisms to gain access to intestinal epithelial cells of the crypt. However, the impact of Salmonella Typhimurium on stem cells and progenitors, which are responsible for the ability of the intestinal epithelium to renew and protect itself, remains unclear. Given that intestinal organoids growth is sustained by stem cells and progenitors activity, we have used this model to document the effects of Salmonella Typhimurium infection on epithelial proliferation and differentiation, and compared it to an in vivo model of Salmonella infection in mice. Among gut segments, the caecum was preferentially targeted by Salmonella. Analysis of infected crypts and organoids demonstrated increased length and size, respectively. mRNA transcription profiles of infected crypts and organoids pointed to upregulated EGFR-dependent signals, associated with a decrease in secretory cell lineage differentiation. To conclude, we show that organoids are suited to mimic the impact of Salmonella on stem cells and progenitors cells, carrying a great potential to drastically reduce the use of animals for scientific studies on that topic. In both models, the EGFR pathway, crucial to stem cells and progenitors proliferation and differentiation, is dysregulated by Salmonella, suggesting that repeated infections might have consequences on crypt integrity and further oncogenesis. [ABSTRACT FROM AUTHOR]

A tunable ultrashort soliton pulse source reaching up to 4.8 µm is demonstrated based on a 2.8 µm femtosecond fiber laser coupled to a zirconium fluoride fiber amplifier followed by a small core indium fluoride fiber. This demonstration is extending by 300 nm the long wavelength limit previously reported with soliton self-frequency shift (SSFS) sources based on fluoride fibers. Our experimental and numerical investigation highlighted the spectral dynamics associated with the generation of highly redshifted pulses in the mid-infrared using SSFS enhanced by soliton fission. This study is intended at providing a better understanding of the potential and limitations of SSFS based tunable femtosecond fiber sources in the 3–5 µm spectral range. [ABSTRACT FROM AUTHOR]

An aqueous marine-sulfated polysaccharide (MSP) extract, prepared from the green macroalga Ulva armoricana, was tested as an antibacterial compound against 42 bacterial strains and isolates found in livestock animals. Both Gram-positive and Gram-negative bacteria growths were affected. The most susceptible pathogens were Pasteurella multocida, Mannheimia haemolytica, Erysipelothrix rhusiopathiae, Staphylococcus aureus, and Streptococcus suis, with a minimum inhibitory concentration (MIC) ranging from 0.16 to 6.25 mg mL. Enterococcus cecorum, Streptococcus dysgalactiae, Corynebacterium, Trueperella pyogenes, and Bordetella bronchiseptica strains were also susceptive to MSP with a complete inhibition recorded at MIC values of 25 and 50 mg mL. The stimulation of the immune response mediators of the host's gut with the extract was evaluated using an in vitro system of differentiated porcine intestinal epithelial cells (IPEC-1). RT-qPCR analysis showed a significant increase of mRNA expression of cytokines such as IL1α, IL1β, L6, IL8, TNFα, and TGFβ as well as the chemokine CCL20. The extract also significantly induced the expression of PPARγ, a ligand-activated transcription factor, and TLR2 receptor. [ABSTRACT FROM AUTHOR]

Abstract  Systems biology aims at integrating processes at various time and spatial scales into a single and coherent formal description to allow computer modeling. In this context, we focus on rule-based modeling and its integration in the domain-specific language MGS . Through the notions of topological collections and transformations, MGS allows the modeling of biological processes at various levels of description. We validate our approach through the description of various models of the genetic switch of the λ phage, from a very simple biochemical description of the process to an individual-based model on a Delaunay graph topology. This approach is a first step into providing the requirements for the emerging field of spatial systems biology which integrates spatial properties into systems biology. [ABSTRACT FROM AUTHOR]

Objective: Esophageal Doppler allows continuous monitoring of stroke volume index (SVI) and corrected flow time (FTc). We hypothesized that variations in stroke output index SOI (SVI/FTc) during volume expansion can predict the hemodynamic response to subsequent fluid loading better than the static values.Design and Setting: Prospective study in the intensive care unit of a university hospital.Patients: Fifty-one patients with circulatory failure were monitored by esophageal Doppler.Interventions: Patients who responded to a first fluid challenge received a second one. Patients who responded to both were classified as responders-responders, and those who did not respond to the second as responders-nonresponders. In these two groups we compared DeltaSVI, DeltaFTc, and DeltaSOI during each fluid challenge and also static values at the end of each fluid challenge.Measurements and Results: After the first fluid challenge DeltaSOI and DeltaSVI were significantly higher in patients who responded to subsequent volume expansion than in patients who no longer responded. ROC curves showed that DeltaSOI was a better predictor of fluid responsiveness than DeltaSVI. During volume expansion a DeltaSOI value of 11% discriminated between responders and nonresponders to subsequent volume expansion with a sensitivity of 91% and a specificity of 97%. There was no significant difference between the two groups for FTc value at the end of first fluid challenge.Conclusions: Analysis of DeltaSOI during fluid challenge predicts response to subsequent fluid challenge and FTc is not a reliable indicator of cardiac preload. [ABSTRACT FROM AUTHOR]