Fatigue-related group III/IV muscle afferent feedback facilitates intracortical inhibition during locomotor exercise

Key Points: This study investigated the influence of group III/IV muscle afferents on corticospinal excitability during cycling exercise and focused on GABAB neuron-mediated inhibition as a potential underlying mechanism. The study provides novel evidence to demonstrate that group III/IV muscle afferent feedback facilitates inhibitory intracortical neurons during whole body exercise. Firing of these interneurons probably contributes to the development of central fatigue during physical activity. Abstract: We investigated the influence of group III/IV muscle afferents in determining corticospinal excitability during cycling exercise and focused on GABAB neuron-mediated inhibition as a potential underlying mechanism. Both under control conditions (CTRL) and with lumbar intrathecal fentanyl (FENT) impairing feedback from group III/IV leg muscle afferents, subjects (n = 11) cycled at a comparable vastus-lateralis EMG signal (∼0.26 mV) before (PRE; 100 W) and immediately after (POST; 90 ± 2 W) fatiguing constant-load cycling exercise (80% Wpeak; 221 ± 10 W; ∼8 min). During, PRE and POST cycling, single and paired-pulse (100 ms interstimulus interval) transcranial magnetic stimulations (TMS) were applied to elicit unconditioned and conditioned motor-evoked potentials (MEPs), respectively. To distinguish between cortical and spinal contributions to the MEPs, cervicomedullary stimulations (CMS) were used to elicit unconditioned (CMS only) and conditioned (TMS+CMS, 100 ms interval) cervicomedullary motor-evoked potentials (CMEPs). While unconditioned MEPs were unchanged from PRE to POST in CTRL, unconditioned CMEPs increased significantly, resulting in a decrease in unconditioned MEP/CMEP (P 0.2). These findings reveal that feedback from group III/IV muscle afferents innervating locomotor muscle decreases the excitability of the motor cortex during fatiguing cycling exercise. This impairment is, at least in part, determined by the facilitating effect of these sensory neurons on inhibitory GABAB intracortical interneurons.Simranjit K. Sidhu, Joshua C. Weavil, Taylor S. Thurston, Dorothea Rosenberger, Jacob E. Jessop, Eivind Wang, Russell S. Richardson, Chris J. McNeil, and Markus Aman

IRAK-4 mutation (Q293X): Rapid detection and characterization of defective post-transcriptional TLR/IL-1R responses in human myeloid and non-myeloid cells

Innate immunodeficiency has recently been reported as resulting from the Q293X IRAK-4 mutation with consequent defective TLR/IL-1R signaling. In this study we report a method for the rapid allele-specific detection of this mutation and demonstrate both cell type specificity and ligand specificity in defective IL-1R-associated kinase (IRAK)-4-deficient cellular responses, indicating differential roles for this protein in human PBMCs and primary dermal fibroblasts and in LPS, IL-1β, and TNF-α signaling. We demonstrate transcriptional and post-transcriptional defects despite NF-κB signaling and intact MyD88-independent signaling and propose that dysfunctional complex 1 (IRAK1/TRAF6/TAK1) signaling, as a consequence of IRAK-4 deficiency, generates specific defects in MAPK activation that could underpin this patient's innate immunodeficiency. These studies demonstrate the importance of studying primary human cells bearing a clinically relevant mutation; they underscore the complexity of innate immune signaling and illuminate novel roles for IRAK-4 and the fundamental importance of accessory proinflammatory signaling to normal human innate immune responses and immunodeficiencies

Levelling the playing field: A case study of how non-market values can compete in policy debates over wastewater allocation in a semi-arid region

In this paper we describe how benefits are transferred from previous non-market valuation research to inform the public policy debate on the allocation of treated wastewater to Riparian Projects in the semi-arid city of Tucson, Arizona, United States. Specifically, we transfer property premiums associated with proximity to riparian habitat to two proposed, and one accidental, urban Riparian Project. The study demonstrates that nearby property owners would likely benefit from wastewater reuse in riparian corridor restoration projects. Furthermore, the variable costs of supplying supplementary treated wastewater to one of the Riparian Projects are covered by incremental property tax revenues. We conclude that there is a window of opportunity to utilize a portion of Tucson's treated wastewater, over half of which is currently discharged at the northern end of the city, for additional in-town riparian restoration projects. Such riparian restoration projects also provide a mechanism for Endangered Species Act compliance

Deciphering associations between three RNA splicing-related genetic variants and lung cancer risk.

Limited efforts have been made in assessing the effect of genome-wide profiling of RNA splicing-related variation on lung cancer risk. In the present study, we first identified RNA splicing-related genetic variants linked to lung cancer in a genome-wide profiling analysis and then conducted a two-stage (discovery and replication) association study in populations of European ancestry. Discovery and validation were conducted sequentially with a total of 29,266 cases and 56,450 controls from both the Transdisciplinary Research in Cancer of the Lung and the International Lung Cancer Consortium as well as the OncoArray database. For those variants identified as significant in the two datasets, we further performed stratified analyses by smoking status and histological type and investigated their effects on gene expression and potential regulatory mechanisms. We identified three genetic variants significantly associated with lung cancer risk: rs329118 in JADE2 (P = 8.80E−09), rs2285521 in GGA2 (P = 4.43E−08), and rs198459 in MYRF (P = 1.60E−06). The combined effects of all three SNPs were more evident in lung squamous cell carcinomas (P = 1.81E−08, P = 6.21E−08, and P = 7.93E−04, respectively) than in lung adenocarcinomas and in ever smokers (P = 9.80E−05, P = 2.70E−04, and P = 2.90E−05, respectively) than in never smokers. Gene expression quantitative trait analysis suggested a role for the SNPs in regulating transcriptional expression of the corresponding target genes. In conclusion, we report that three RNA splicing-related genetic variants contribute to lung cancer susceptibility in European populations. However, additional validation is needed, and specific splicing mechanisms of the target genes underlying the observed associations also warrants further exploration