Distinguished non-Archimedean representations

For a symmetric space (G,H), one is interested in understanding the vector space of H-invariant linear forms on a representation \pi of G. In particular an important question is whether or not the dimension of this space is bounded by one. We cover the known results for the pair (G=R_{E/F}GL(n),H=GL(n)), and then discuss the corresponding SL(n) case. In this paper, we show that (G=R_{E/F}SL(n),H=SL(n)) is a Gelfand pair when n is odd. When $n$ is even, the space of H-invariant forms on \pi can have dimension more than one even when \pi is supercuspidal. The latter work is joint with Dipendra Prasad

Markers of serotonergic function in the orbitofrontal cortex and dorsal raphé nucleus predict individual variation in spatial-discrimination serial reversal learning.

Dysfunction of the orbitofrontal cortex (OFC) impairs the ability of individuals to flexibly adapt behavior to changing stimulus-reward (S-R) contingencies. Impaired flexibility also results from interventions that alter serotonin (5-HT) and dopamine (DA) transmission in the OFC and dorsomedial striatum (DMS). However, it is unclear whether similar mechanisms underpin naturally occurring variations in behavioral flexibility. In the present study, we used a spatial-discrimination serial reversal procedure to investigate interindividual variability in behavioral flexibility in rats. We show that flexibility on this task is improved following systemic administration of the 5-HT reuptake inhibitor citalopram and by low doses of the DA reuptake inhibitor GBR12909. Rats in the upper quintile of the distribution of perseverative responses during repeated S-R reversals showed significantly reduced levels of the 5-HT metabolite, 5-hydroxy-indoleacetic acid, in the OFC. Additionally, 5-HT2A receptor binding in the OFC of mid- and high-quintile rats was significantly reduced compared with rats in the low-quintile group. These perturbations were accompanied by an increase in the expression of monoamine oxidase-A (MAO-A) and MAO-B in the lateral OFC and by a decrease in the expression of MAO-A, MAO-B, and tryptophan hydroxylase in the dorsal raphé nucleus of highly perseverative rats. We found no evidence of significant differences in markers of DA and 5-HT function in the DMS or MAO expression in the ventral tegmental area of low- vs high-perseverative rats. These findings indicate that diminished serotonergic tone in the OFC may be an endophenotype that predisposes to behavioral inflexibility and other forms of compulsive behavior.This work was supported by Medical Research Council Grants (G0701500; G0802729), a 503 Wellcome Trust Programme Grant (grant number 089589/Z/09/Z), and by a Core Award 504 from the Medical Research Council and the Wellcome Trust to the Behavioural and Clinical 505 21 Neuroscience Institute (MRC Ref G1000183; WT Ref 093875/Z/10/Z). RLB was supported 506 by a studentship from the Medical Research Council. JA was supported by a Fellowship from 507 the Swedish Research Council (350-2012-230). BJ was supported by Fellowships from the 508 AXA Research Fund and the National Health and Medical Research Council of Australia. 509 Financial support from the Fredrik and Ingrid Thuring Foundation is also acknowledged.This is the accepted manuscript. The final version is available from Nature Publishing at http://www.nature.com/npp/journal/vaop/ncurrent/full/npp2014335a.html

Antiviral medications for preventing cytomegalovirus disease in solid organ transplant recipients

Background: Antiviral prophylaxis is commonly used in recipients of solid-organ transplants with the aim of preventing the clinical syndrome associated with cytomegalovirus infection. We undertook a systematic review to investigate whether this approach affects risks of cytomegalovirus disease and death. Methods: Randomised controlled trials of prophylaxis with antiviral medications for cytomegalovirus disease in solid-organ-transplant recipients were identified. Data were combined in meta-analyses by a random-effects model. Findings: Compared with placebo or no treatment, prophylaxis with aciclovir, ganciclovir, or valaciclovir significantly reduced the risks of cytomegalovirus disease (19 trials, 1981 patients; relative risk 0.42 [95% CI 0.34-0.52]), cytomegalovirus infection (17 trials, 1786 patients; 0.61 [0.48-0.77]), and all-cause mortality (17 trials, 1838 patients; 0.63 [0.43-0.92]), mainly owing to lower mortality from cytomegalovirus disease (seven trials, 1300 patients; 0.26 [0.08-0.78]). Prophylaxis also lowered the risks of disease caused by herpes simplex or zoster virus, bacterial infections, and protozoal infections, but not fungal infection, acute rejection, or graft loss. Meta-regression showed no significant difference in the risk of cytomegalovirus disease or all-cause mortality by organ transplanted or cytomegalovirus serostatus; no conclusions were possible for cytomegalovirus-negative recipients of negative organs. In trials of direct comparisons, ganciclovir was more effective than aciclovir in preventing cytomegalovirus disease. Valganciclovir and intravenous ganciclovir were as effective as oral ganciclovir. Interpretation: Prophylaxis with antiviral medications reduces the risk of cytomegalovirus disease and associated mortality in recipients of solid-organ transplants. This approach should be used routinely in cytomegalovirus-positive recipients and in cytomegalovirus-negative recipients of organs positive for the virus

Tests for latent tuberculosis in people with ESRD: A systematic review

Background: The relative diagnostic accuracy of interferon γ release assays (IGRAs; based on ELISA [enzyme-linked immunosorbent assay] or ELISPOT [enzyme-linked immunosorbent spot], ie, the QuantiFERON and T-SPOT.TB tests, respectively) and the tuberculin skin test (TST) for latent tuberculosis (TB) infection in people with end-stage kidney disease is uncertain and national guidelines for their use are inconsistent. Study Design: Systematic review. Selection Criteria for Studies: Evaluated performance of tests for latent TB with clinical risk-factor assessment. Setting & Population: People with end-stage kidney disease (chronic kidney disease stage 5 [eGFR <15] or kidney transplant recipients). No limits on setting. Index Tests: ELISA- or ELISPOT-based IGRAs, TST, assays to detect antimycobacterial antibodies, and flow cytometry-based tests. Outcomes: Odds of test positivity with clinical risk factor for latent TB, expressed as ORs and relative ORs (RORs). Results: 47 studies (6,828 participants) were included, but only 30 studies (4,546 participants) contained sufficient data to contribute to meta-analysis. Studies were predominately in the dialysis population (23/30; 3,700 participants) in countries with low to moderate TB prevalence (0.0-50.0 cases/105 persons). BCG vaccination rate was variable (2.7%-100.0%). 9 studies compared IGRAs with the TST directly, 17 studies evaluated the TST only, and the other 4 studies evaluated other tests. Compared to a positive TST result, a positive ELISA-based IGRA result was associated more strongly with radiologic evidence of past TB (ROR, 4.29; 95% CI, 1.83-10.3; P = 0.001) and contact with active TB (ROR, 3.36; 95% CI, 1.61-7.01; P = 0.001). Compared to a negative TST result, a negative ELISA-based IGRA result was associated more strongly with BCG vaccination (ROR, 0.30; 95% CI, 0.14-0.63; P = 0.002). There were insufficient data to compare performance of the ELISPOT-based IGRA with the TST or ELISA-based IGRA. Limitations: 17 of 47 included studies (36.2%) did not contain sufficient data to contribute to meta-analysis. Conclusions: Compared to the TST, the ELISA-based IGRA was associated more strongly with risk factors for latent TB in end-stage kidney disease. © 2012 National Kidney Foundation, Inc

On distinguished square-integrable representations for Galois pairs and a conjecture of Prasad

International audienceWe prove an integral formula computing multiplicities of square-integrable representations relative to Galois pairs over $p$-adic fields and we apply this formula to verify two consequences of a conjecture of Dipendra Prasad. One concerns the exact computation of the multiplicity of the Steinberg representation and the other the invariance of multiplicities by transfer among inner forms

Transient stimulation of distinct subpopulations of striatal neurons mimics changes in action value

In changing environments animals must adaptively select actions to achieve their goals. In tasks involving goal-directed action selection, striatal neural activity has been shown to represent the value of competing actions. Striatal representations of action value could potentially bias responses toward actions of higher value. However, no study to date has demonstrated the direct impact of distinct striatal pathways in goal-directed action selection. Here we show in mice that transient optogenetic stimulation of dorsal striatal dopamine D1 and D2 receptor-expressing neurons during decision-making introduces opposing biases in the distribution of choices. The effect of stimulation on choice is dependent on recent reward history and mimics an additive change in the action value. While stimulation prior to and during movement initiation produces a robust bias in choice behavior, this bias is significantly diminished when stimulation is delayed after response initiation. Together, our data demonstrate the role of striatal activity in goal-directed action selection