The resident prokaryotic microbiota of the metazoan gut elicits profound effects on the growth and development of the intestine. However, the molecular mechanisms of symbiotic prokaryotic–eukaryotic ...cross‐talk in the gut are largely unknown. It is increasingly recognized that physiologically generated reactive oxygen species (ROS) function as signalling secondary messengers that influence cellular proliferation and differentiation in a variety of biological systems. Here, we report that commensal bacteria, particularly members of the genus Lactobacillus, can stimulate NADPH oxidase 1 (Nox1)‐dependent ROS generation and consequent cellular proliferation in intestinal stem cells upon initial ingestion into the murine or Drosophila intestine. Our data identify and highlight a highly conserved mechanism that symbiotic microorganisms utilize in eukaryotic growth and development. Additionally, the work suggests that specific redox‐mediated functions may be assigned to specific bacterial taxa and may contribute to the identification of microbes with probiotic potential.
Non‐pathogenic gut bacteria promote ROS generation in host epithelial cells, thereby regulating intestinal homeostasis in both mammals and insects.
We present a dual-stage, wideband gain-flattened ytterbium-doped fiber amplifier specifically tailored for <inline-formula> <tex-math notation="LaTeX">1~\mu </tex-math></inline-formula>m data ...transmission. By optimizing each amplifier stage and incorporating a gain flattening filter, our amplifier provides impressive wideband performance, with an average gain of 20 dB, spectral gain variation of <1 dB, and noise figure of <5.7 dB over a gain bandwidth of 50 nm (1025-1075 nm) - corresponding to an enhanced gain bandwidth of ~13.7 THz in the frequency domain, which is nearly 3.1 times greater than that of the C-band erbium-doped fiber amplifier. Our wideband amplifier offers significant potential for high-capacity wavelength-division multiplexed transmission in the <inline-formula> <tex-math notation="LaTeX">1~\mu </tex-math></inline-formula>m wavelength regime.
Roadmap of optical communications Agrell, Erik; Karlsson, Magnus; Chraplyvy, A R ...
Journal of optics (2010),
06/2016, Letnik:
18, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Lightwave communications is a necessity for the information age. Optical links provide enormous bandwidth, and the optical fiber is the only medium that can meet the modern society's needs for ...transporting massive amounts of data over long distances. Applications range from global high-capacity networks, which constitute the backbone of the internet, to the massively parallel interconnects that provide data connectivity inside datacenters and supercomputers. Optical communications is a diverse and rapidly changing field, where experts in photonics, communications, electronics, and signal processing work side by side to meet the ever-increasing demands for higher capacity, lower cost, and lower energy consumption, while adapting the system design to novel services and technologies. Due to the interdisciplinary nature of this rich research field, Journal of Optics has invited 16 researchers, each a world-leading expert in their respective subfields, to contribute a section to this invited review article, summarizing their views on state-of-the-art and future developments in optical communications.
Extracellular microbe-mineral electron transfer is a major driving force for the oxidation of organic carbon in many subsurface environments. Extracellular multi-heme cytochromes of the Shewenella ...genus play a major role in this process but the mechanism of electron exchange at the interface between cytochrome and acceptor is widely debated. The 1.8 Å x-ray crystal structure of the decaheme MtrC revealed a highly conserved CX8C disulfide that, when substituted for AX8A, severely compromised the ability of S. oneidensis to grow under aerobic conditions. Reductive cleavage of the disulfide in the presence of flavin mononucleotide (FMN) resulted in the reversible formation of a stable flavocytochrome. Similar results were also observed with other decaheme cytochromes, OmcA, MtrF and UndA. The data suggest that these decaheme cytochromes can transition between highly reactive flavocytochromes or less reactive cytochromes, and that this transition is controlled by a redox active disulfide that responds to the presence of oxygen.
The liver and intestine play crucial roles in maintaining bile acid homeostasis. Here, we demonstrate that fibroblast growth factor 15 (FGF15) signals from intestine to liver to repress the gene ...encoding cholesterol 7α-hydroxylase (CYP7A1), which catalyzes the first and rate-limiting step in the classical bile acid synthetic pathway. FGF15 expression is stimulated in the small intestine by the nuclear bile acid receptor FXR and represses
Cyp7a1 in liver through a mechanism that involves FGF receptor 4 (FGFR4) and the orphan nuclear receptor SHP. Mice lacking FGF15 have increased hepatic CYP7A1 mRNA and protein levels and corresponding increases in CYP7A1 enzyme activity and fecal bile acid excretion. These studies define FGF15 and FGFR4 as components of a gut-liver signaling pathway that synergizes with SHP to regulate bile acid synthesis.
Obstruction of bile flow results in bacterial proliferation and mucosal injury in the small intestine that can lead to the translocation of bacteria across the epithelial barrier and systemic ...infection. These adverse effects of biliary obstruction can be inhibited by administration of bile acids. Here we show that the farnesoid X receptor (FXR), a nuclear receptor for bile acids, induces genes involved in enteroprotection and inhibits bacterial overgrowth and mucosal injury in ileum caused by bile duct ligation. Mice lacking FXR have increased ileal levels of bacteria and a compromised epithelial barrier. These findings reveal a central role for FXR in protecting the distal small intestine from bacterial invasion and suggest that FXR agonists may prevent epithelial deterioration and bacterial translocation in patients with impaired bile flow.
We incorporate two major types of SDM fibers (i.e. few mode fibers and multicore fibers) in a micro-optic collimator assembly and realize fully integrated multiport SDM fiber components (e.g. ...<inline-formula> <tex-math notation="LaTeX">1\times 2 </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">2\times 2 </tex-math></inline-formula> beam splitters). The device fabrication procedure for SDM fibers is similar to that for a standard single mode fiber, but more accurate fiber alignment (e.g. lateral positioning for few mode fiber components and rotational alignment for multicore fiber components) is required to achieve both low mode (core) dependent loss and/or low inter-modal (inter-core) crosstalk. A number of exemplary multiport SDM components are fabricated with low excess loss (1-2.2 dB), low mode (core) dependent loss (< 1 dB) and moderate crosstalk (< −32 dB for a multicore fiber splitter and < −6.5 dB for a few mode fiber splitter).
Abstract Background Peritoneal resuscitation (PR) represents a unique modality of treatment for severely injured trauma patients requiring damage control surgery (DCS). These data represent the ...outcome of a single institution RCT into the efficacy of PR as a management option in these patients. Study Design From 2011-2015, 103 patients were enrolled in a prospective RCT evaluating the utility of PR in the treatment of patients undergoing DCS compared to conventional resuscitation (CR) alone. Patient demographics, clinical variables and outcomes were collected. Univariate and multivariate analysis was performed with a priori significance at p ≤ 0.05. Results After initial screening 52 randomized to PR group and 51 to the CR group. Age, gender, initial pH, and mechanism of injury were used for randomization. Method of abdominal closure was standardized across groups. Time to definitive abdominal closure was reduced in the PR group compared to the CR group (4.1 ± 2.2 days vs 5.9 ± 3.5 days, p ≤ 0.002). Volume of resuscitation and blood products transfused in the initial 24 hours was not different between the groups. Primary fascial closure rate was higher in the PR group (83% vs. 66%, p ≤ 0.05). Intraabdominal complications were lower in the PR compared to the CR group (8% vs 18%) with abscess formation rate (3% vs 14% , p < 0.05) being significant. Patients in the PR group had lower 30 day mortality despite similar ISS scores (13% vs 28%, p=0.06) Conclusions Peritoneal resuscitation enhances the management of DCS patients via reducing time to definitive abdominal closure, reducing intra-abdominal infections and reducing mortality.
CymA (tetrahaem cytochrome c) is a member of the NapC/NirT family of quinol dehydrogenases. Essential for the anaerobic respiratory flexibility of shewanellae, CymA transfers electrons from ...menaquinol to various dedicated systems for the reduction of terminal electron acceptors including fumarate and insoluble minerals of Fe(III). Spectroscopic characterization of CymA from Shewanella oneidensis strain MR-1 identifies three low-spin His/His co-ordinated c-haems and a single high-spin c-haem with His/H(2)O co-ordination lying adjacent to the quinol-binding site. At pH 7, binding of the menaquinol analogue, 2-heptyl-4-hydroxyquinoline-N-oxide, does not alter the mid-point potentials of the high-spin (approximately -240 mV) and low-spin (approximately -110, -190 and -265 mV) haems that appear biased to transfer electrons from the high- to low-spin centres following quinol oxidation. CymA is reduced with menadiol (E(m) = -80 mV) in the presence of NADH (E(m) = -320 mV) and an NADH-menadione (2-methyl-1,4-naphthoquinone) oxidoreductase, but not by menadiol alone. In cytoplasmic membranes reduction of CymA may then require the thermodynamic driving force from NADH, formate or H2 oxidation as the redox poise of the menaquinol pool in isolation is insufficient. Spectroscopic studies suggest that CymA requires a non-haem co-factor for quinol oxidation and that the reduced enzyme forms a 1:1 complex with its redox partner Fcc3 (flavocytochrome c3 fumarate reductase). The implications for CymA supporting the respiratory flexibility of shewanellae are discussed.
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