Nanosensor Detection of an Immunoregulatory Tryptophan Influx/Kynurenine Efflux Cycle

Mammalian cells rely on cellular uptake of the essential amino acid tryptophan. Tryptophan sequestration by up-regulation of the key enzyme for tryptophan degradation, indoleamine 2,3-dioxygenase (IDO), e.g., in cancer and inflammation, is thought to suppress the immune response via T cell starvation. Additionally, the excreted tryptophan catabolites (kynurenines) induce apoptosis of lymphocytes. Whereas tryptophan transport systems have been identified, the molecular nature of kynurenine export remains unknown. To measure cytosolic tryptophan steady-state levels and flux in real time, we developed genetically encoded fluorescence resonance energy transfer nanosensors (FLIPW). The transport properties detected by FLIPW in KB cells, a human oral cancer cell line, and COS-7 cells implicate LAT1, a transporter that is present in proliferative tissues like cancer, in tryptophan uptake. Importantly, we found that this transport system mediates tryptophan/kynurenine exchange. The tryptophan influx/kynurenine efflux cycle couples tryptophan starvation to elevation of kynurenine serum levels, providing a two-pronged induction of apoptosis in neighboring cells. The strict coupling protects cells that overproduce IDO from kynurenine accumulation. Consequently, this mechanism may contribute to immunosuppression involved in autoimmunity and tumor immune escape

Bistability of Slow and Fast Traveling Waves in Fluid Mixtures

The appearence of a new type of fast nonlinear traveling wave states in binary fluid convection with increasing Soret effect is elucidated and the parameter range of their bistability with the common slower ones is evaluated numerically. The bifurcation behavior and the significantly different spatiotemporal properties of the different wave states - e.g. frequency, flow structure, and concentration distribution - are determined and related to each other and to a convenient measure of their nonlinearity. This allows to derive a limit for the applicability of small amplitude expansions. Additionally an universal scaling behavior of frequencies and mixing properties is found. PACS: 47.20.-k, 47.10.+g, 47.20.KyComment: 4 pages including 5 Postscript figure

Review: ‘Gimme five’: future challenges in multiple sclerosis. ECTRIMS Lecture 2009

This article is based on the ECTRIMS lecture given at the 25th ECTRIMS meeting which was held in Düsseldorf, Germany, from 9 to 12 September 2009. Five challenges have been identified: (1) safeguarding the principles of medical ethics; (2) optimizing the risk/benefit ratio; (3) bridging the gap between multiple sclerosis and experimental autoimmune encephalitis; (4) promoting neuroprotection and repair; and (5) tailoring multiple sclerosis therapy to the individual patient. Each of these challenges will be discussed and placed in the context of current research into the pathogenesis and treatment of multiple sclerosis

Influence of through-flow on linear pattern formation properties in binary mixture convection

We investigate how a horizontal plane Poiseuille shear flow changes linear convection properties in binary fluid layers heated from below. The full linear field equations are solved with a shooting method for realistic top and bottom boundary conditions. Through-flow induced changes of the bifurcation thresholds (stability boundaries) for different types of convective solutions are deter- mined in the control parameter space spanned by Rayleigh number, Soret coupling (positive as well as negative), and through-flow Reynolds number. We elucidate the through-flow induced lifting of the Hopf symmetry degeneracy of left and right traveling waves in mixtures with negative Soret coupling. Finally we determine with a saddle point analysis of the complex dispersion relation of the field equations over the complex wave number plane the borders between absolute and convective instabilities for different types of perturbations in comparison with the appropriate Ginzburg-Landau amplitude equation approximation. PACS:47.20.-k,47.20.Bp, 47.15.-x,47.54.+rComment: 19 pages, 15 Postscript figure

Influence of the Soret effect on convection of binary fluids

Convection in horizontal layers of binary fluids heated from below and in particular the influence of the Soret effect on the bifurcation properties of extended stationary and traveling patterns that occur for negative Soret coupling is investigated theoretically. The fixed points corresponding to these two convection structures are determined for realistic boundary conditions with a many mode Galerkin scheme for temperature and concentration and an accurate one mode truncation of the velocity field. This solution procedure yields the stable and unstable solutions for all stationary and traveling patterns so that complete phase diagrams for the different convection types in typical binary liquid mixtures can easily be computed. Also the transition from weakly to strongly nonlinear states can be analyzed in detail. An investigation of the concentration current and of the relevance of its constituents shows the way for a simplification of the mode representation of temperature and concentration field as well as for an analytically manageable few mode description.Comment: 30 pages, 12 figure

Failing boys and moral panics: perspectives on the underachievement debate

The paper re-examines the underachievement debate from the perspective of the ‘discourse of derision’ that surrounds much writing in this area. It considers the contradictions and inconsistencies which underpin much of the discourse – from a reinterpretation of examination scores, to the conflation of the concepts of ‘under’ and ‘low’ achievement and finally to the lack of consensus on a means of defining and measuring the term underachievement. In doing so, this paper suggests a more innovative approach for understanding, re-evaluating and perhaps rejecting the notion of underachievement

Phase II Study of Radiotherapy and Temsirolimus versus Radiochemotherapy with Temozolomide in Patients with Newly Diagnosed Glioblastoma without MGMT Promoter Hypermethylation (EORTC 26082).

EORTC 26082 assessed the activity of temsirolimus in patients with newly diagnosed glioblastoma harboring an unmethylated O6 methylguanine-DNA-methyltransferase (MGMT) promoter. Patients (n = 257) fulfilling eligibility criteria underwent central MGMT testing. Patients with MGMT unmethylated glioblastoma (n = 111) were randomized 1:1 between standard chemo-radiotherapy with temozolomide or radiotherapy plus weekly temsirolimus (25 mg). Primary endpoint was overall survival at 12 months (OS12). A positive signal was considered >38 patients alive at 12 months in the per protocol population. A noncomparative reference arm of 54 patients evaluated the assumptions on OS12 in a standard-treated cohort of patients. Prespecified post hoc analyses of markers reflecting target activation were performed. Both therapies were administered per protocol with a median of 13 cycles of maintenance temsirolimus. Median age was 55 and 58 years in the temsirolimus and standard arms, the WHO performance status 0 or 1 for most patients (95.5%). In the per protocol population, 38 of 54 patients treated with temsirolimus reached OS12. The actuarial 1-year survival was 72.2% [95% confidence interval (CI), 58.2-82.2] in the temozolomide arm and 69.6% (95% CI, 55.8-79.9) in the temsirolimus arm [hazard ratio (HR) 1.16; 95% CI, 0.77-1.76; P = 0.47]. In multivariable prognostic analyses of clinical and molecular factors, phosphorylation of mTORSer2448 in tumor tissue (HR 0.13; 95% CI, 0.04-0.47; P = 0.002), detected in 37.6%, was associated with benefit from temsirolimus. Temsirolimus was not superior to temozolomide in patients with an unmethylated MGMT promoter. Phosphorylation of mTORSer2448 in the pretreatment tumor tissue may define a subgroup benefitting from mTOR inhibition. Clin Cancer Res; 22(19); 4797-806. ©2016 AACR

Phase II Study of Radiotherapy and Temsirolimus versus Radiochemotherapy with Temozolomide in Patients with Newly Diagnosed Glioblastoma without MGMT Promoter Hypermethylation (EORTC 26082).

EORTC 26082 assessed the activity of temsirolimus in patients with newly diagnosed glioblastoma harboring an unmethylated O6 methylguanine-DNA-methyltransferase (MGMT) promoter. Patients (n = 257) fulfilling eligibility criteria underwent central MGMT testing. Patients with MGMT unmethylated glioblastoma (n = 111) were randomized 1:1 between standard chemo-radiotherapy with temozolomide or radiotherapy plus weekly temsirolimus (25 mg). Primary endpoint was overall survival at 12 months (OS12). A positive signal was considered >38 patients alive at 12 months in the per protocol population. A noncomparative reference arm of 54 patients evaluated the assumptions on OS12 in a standard-treated cohort of patients. Prespecified post hoc analyses of markers reflecting target activation were performed. Both therapies were administered per protocol with a median of 13 cycles of maintenance temsirolimus. Median age was 55 and 58 years in the temsirolimus and standard arms, the WHO performance status 0 or 1 for most patients (95.5%). In the per protocol population, 38 of 54 patients treated with temsirolimus reached OS12. The actuarial 1-year survival was 72.2% [95% confidence interval (CI), 58.2-82.2] in the temozolomide arm and 69.6% (95% CI, 55.8-79.9) in the temsirolimus arm [hazard ratio (HR) 1.16; 95% CI, 0.77-1.76; P = 0.47]. In multivariable prognostic analyses of clinical and molecular factors, phosphorylation of mTORSer2448 in tumor tissue (HR 0.13; 95% CI, 0.04-0.47; P = 0.002), detected in 37.6%, was associated with benefit from temsirolimus. Temsirolimus was not superior to temozolomide in patients with an unmethylated MGMT promoter. Phosphorylation of mTORSer2448 in the pretreatment tumor tissue may define a subgroup benefitting from mTOR inhibition. Clin Cancer Res; 22(19); 4797-806. ©2016 AACR

Single cell analysis of kynurenine and System L amino acid transport in T cells

Acknowledgements We thank Cantrell group members for their critical discussion of the data, the Biological Resources unit, Sarah Thomson (for rLM work) and the Flow Cytometry facility (A. Whigham and R. Clarke) at the University of Dundee. This work was supported by the Wellcome Trust (Principal Research Fellowship to D.A.C. 097418/Z/11/Z and 205023/Z/16/Z, and Wellcome Trust Equipment Award 202950/Z/16/Z).Peer reviewedPublisher PD