Coherent interaction of laser pulses in a resonant optically dense extended medium under the regime of strong field-matter coupling

Nonstationary pump-probe interaction between short laser pulses propagating in a resonant optically dense coherent medium is considered. A special attention is paid to the case, where the density of two-level particles is high enough that a considerable part of the energy of relatively weak external laser-fields can be coherently absorbed and reemitted by the medium. Thus, the field of medium reaction plays a key role in the interaction processes, which leads to the collective behavior of an atomic ensemble in the strongly coupled light-matter system. Such behavior results in the fast excitation interchanges between the field and a medium in the form of the optical ringing, which is analogous to polariton beating in the solid-state optics. This collective oscillating response, which can be treated as successive beats between light wave-packets of different group velocities, is shown to significantly affect propagation and amplification of the probe field under its nonlinear interaction with a nearly copropagating pump pulse. Depending on the probe-pump time delay, the probe transmission spectra show the appearance of either specific doublet or coherent dip. The widths of these features are determined by the density-dependent field-matter coupling coefficient and increase during the propagation. Besides that, the widths of the coherent features, which appear close to the resonance in the broadband probe-spectrum, exceed the absorption-line width, since, under the strong-coupling regime, the frequency of the optical ringing exceeds the rate of incoherent relaxation. Contrary to the stationary strong-field effects, the density- and coordinate-dependent transmission spectra of the probe manifest the importance of the collective oscillations and cannot be obtained in the framework of the single-atom model.Comment: 10 pages, 8 figures, to be published in Phys. Rev.

Complete Structural Model of Escherichia coli RNA Polymerase from a Hybrid Approach

A combination of structural approaches yields a complete atomic model of the highly biochemically characterized Escherichia coli RNA polymerase, enabling fuller exploitation of E. coli as a model for understanding transcription

A genome-wide DNA methylation signature for SETD1B-related syndrome

SETD1B is a component of a histone methyltransferase complex that specifically methylates Lys-4 of histone H3 (H3K4) and is responsible for the epigenetic control of chromatin structure and gene expression. De novo microdeletions encompassing this gene as well as de novo missense mutations were previously linked to syndromic intellectual disability (ID). Here, we identify a specific hypermethylation signature associated with loss of function mutations in the SETD1B gene which may be used as an epigenetic marker supporting the diagnosis of syndromic SETD1B-related diseases. We demonstrate the clinical utility of this unique epi-signature by reclassifying previously identified SETD1B VUS (variant of uncertain significance) in two patients

Concurrent Oral 1 - Rheumatoid Arthritis: Treatment [OP4-OP9]: OP4. Inhibition of Radiographic Progression and Improvements in Physical Function at 2 Years, with Increasing Clinical Efficacy Over Time, in Rheumatoid Arthritis (Ra) Patients Treated with Tocilizumab (Tcz): The Lithe Study

Background: Patients with moderate to severe RA who remained on methotrexate (MTX) despite inadequate response were treated with TCZ in a double-blind, randomized, controlled phase 3 trial. Results of a 2-year planned analysis from this study are presented. Methods: Patients were randomized to treatment with TCZ 4 mg/kg + MTX (TCZ4), TCZ 8 mg/kg + MTX (TCZ8) or placebo + MTX (CON) every 4 weeks. If patients failed to respond ( 60% of patients and the DAS28 remission (DAS28 < 2.6) rate was 48% at week 52 and continued to increase to week 104. By week 52, patients treated with TCZ8 had clinically significant improvements in SJC that were maintained through week 104. Rates per 100 PY for adverse events (AEs) were higher in TCZ8 and TCZ4 (263.6, 275.4) vs CON patients (251.4) while rates for serious AEs were comparable (11.4, 12.1, 10.9, respectively). Rates per 100 PY of AEs leading to withdrawal (7.4, 32.5, 4.8) and treatment modification (8.4, 30.7, 20.4) were higher in TCZ8 and TCZ4 vs CON patients, respectively and death rates were comparable (0.6, 0.2, 0.4). Conclusions: Treatment with TCZ + MTX inhibits radiographic progression over 2 years and improves physical function as shown by DAS28 remission, LDAS and low SJC, with a manageable safety profile. Disclosure statement: E.A., F. Hoffmann-La Roche - Employee. P.A., F. Hoffmann-La Roche - Employee. R.B.-V., F. Hoffmann-La Roche - Honoraria. R.F., Genentech - Research Funding, Honoraria. J.K., F. Hoffmann-La Roche - Research funding, Honorari

Lubiprostone ameliorates the cystic fibrosis mouse intestinal phenotype

<p>Abstract</p> <p>Background</p> <p>Cystic fibrosis (CF) is caused by mutations in the <it>CFTR </it>gene that impair the function of CFTR, a cAMP-regulated anion channel. In the small intestine loss of CFTR function creates a dehydrated, acidic luminal environment which is believed to cause an accumulation of mucus, a phenotype characteristic of CF. CF mice have small intestinal bacterial overgrowth, an altered innate immune response, and impaired intestinal transit. We investigated whether lubiprostone, which can activate the CLC2 Cl^-channel, would improve the intestinal phenotype in CF mice.</p> <p>Methods</p> <p><it>Cftr^tm1UNC</it>(CF) and wildtype (WT) littermate mice on the C57BL/6J background were used. Lubiprostone (10 μg/kg-day) was administered by gavage for two weeks. Mucus accumulation was estimated from crypt lumen widths in periodic acid-Schiff base, Alcian blue stained sections. Luminal bacterial load was measured by qPCR for the bacterial 16<it>S </it>gene. Gastric emptying and small intestinal transit in fasted mice were assessed using gavaged rhodamine dextran. Gene expression was evaluated by Affymetrix Mouse430 2.0 microarray and qRT-PCR.</p> <p>Results</p> <p>Crypt width in control CF mice was 700% that of WT mice (<it>P </it>< 0.001). Lubiprostone did not affect WT crypt width but, unexpectedly, increased CF crypt width 22% (<it>P </it>= 0.001). Lubiprostone increased bacterial load in WT mice to 490% of WT control levels (<it>P </it>= 0.008). Conversely, lubiprostone decreased bacterial overgrowth in CF mice by 60% (<it>P </it>= 0.005). Lubiprostone increased gastric emptying at 20 min postgavage in both WT (<it>P </it>< 0.001) and CF mice (<it>P </it>< 0.001). Lubiprostone enhanced small intestinal transit in WT mice (<it>P </it>= 0.024) but not in CF mice (<it>P </it>= 0.377). Among other innate immune markers, expression of mast cell genes was elevated 4-to 40-fold in the CF intestine as compared to WT, and lubiprostone treatment of CF mice decreased expression to WT control levels.</p> <p>Conclusions</p> <p>These results indicate that lubiprostone has some benefits for the CF intestinal phenotype, especially on bacterial overgrowth and the innate immune response. The unexpected observation of increased mucus accumulation in the crypts of lubiprostone-treated CF mice suggests the possibility that lubiprostone increases mucus secretion.</p

Immunological mechanism of action and clinical profile of disease-modifying treatments in multiple sclerosis.

Multiple sclerosis (MS) is a life-long, potentially debilitating disease of the central nervous system (CNS). MS is considered to be an immune-mediated disease, and the presence of autoreactive peripheral lymphocytes in CNS compartments is believed to be critical in the process of demyelination and tissue damage in MS. Although MS is not currently a curable disease, several disease-modifying therapies (DMTs) are now available, or are in development. These DMTs are all thought to primarily suppress autoimmune activity within the CNS. Each therapy has its own mechanism of action (MoA) and, as a consequence, each has a different efficacy and safety profile. Neurologists can now select therapies on a more individual, patient-tailored basis, with the aim of maximizing potential for long-term efficacy without interruptions in treatment. The MoA and clinical profile of MS therapies are important considerations when making that choice or when switching therapies due to suboptimal disease response. This article therefore reviews the known and putative immunological MoAs alongside a summary of the clinical profile of therapies approved for relapsing forms of MS, and those in late-stage development, based on published data from pivotal randomized, controlled trials

Murine Models and Cell Lines for the Investigation of Pheochromocytoma: Applications for Future Therapies?

Pheochromocytomas (PCCs) are slow-growing neuroendocrine tumors arising from adrenal chromaffin cells. Tumors arising from extra-adrenal chromaffin cells are called paragangliomas. Metastases can occur up to approximately 60% or even more in specific subgroups of patients. There are still no well-established and clinically accepted “metastatic” markers available to determine whether a primary tumor is or will become malignant. Surgical resection is the most common treatment for non-metastatic PCCs, but no standard treatment/regimen is available for metastatic PCC. To investigate what kind of therapies are suitable for the treatment of metastatic PCC, animal models or cell lines are very useful. Over the last two decades, various mouse and rat models have been created presenting with PCC, which include models presenting tumors that are to a certain degree biochemically and/or molecularly similar to human PCC, and develop metastases. To be able to investigate which chemotherapeutic options could be useful for the treatment of metastatic PCC, cell lines such as mouse pheochromocytoma (MPC) and mouse tumor tissue (MTT) cells have been recently introduced and they both showed metastatic behavior. It appears these MPC and MTT cells are biochemically and molecularly similar to some human PCCs, are easily visualized by different imaging techniques, and respond to different therapies. These studies also indicate that some mouse models and both mouse PCC cell lines are suitable for testing new therapies for metastatic PCC