GABAA-Mediated Inhibition Modulates Stimulus-Specific Adaptation in the Inferior Colliculus

The ability to detect novel sounds in a complex acoustic context is crucial for survival. Neurons from midbrain through cortical levels adapt to repetitive stimuli, while maintaining responsiveness to rare stimuli, a phenomenon called stimulus-specific adaptation (SSA). The site of origin and mechanism of SSA are currently unknown. We used microiontophoretic application of gabazine to examine the role of GABAA-mediated inhibition in SSA in the inferior colliculus, the midbrain center for auditory processing. We found that gabazine slowed down the process of adaptation to high probability stimuli but did not abolish it, with response magnitude and latency still depending on the probability of the stimulus. Blocking GABAA receptors increased the firing rate to high and low probability stimuli, but did not completely equalize the responses. Together, these findings suggest that GABAA-mediated inhibition acts as a gain control mechanism that enhances SSA by modifying the responsiveness of the neuron

Patterns of smoking behavior among physicians in Yerevan, Armenia

BACKGROUND: Physicians can play an important role in smoking prevention and control. This study will identify smoking prevalence among physicians in Yerevan, Armenia. It will also explore how the smoking behaviors of physicians, their perceived ability to influence patient smoking behavior, and their knowledge about health outcomes related to smoking influence their interaction with patients. METHODS: A cross-sectional, self-administered, anonymous survey was conducted in July, 2004, among 12 healthcare facilities in Yerevan. Analyses are based on responses from 240 physicians, representing a 70% response rate. RESULTS: The percentage of current smokers was significantly higher in men than women (48.5% vs. 12.8% regular and 6.8% vs. 4.5% occasional). Among current smokers, 52.7% of men compared with 13.0% of women had previously smoked in the presence of patients. Only 35.3% felt well prepared to assist patients to quit smoking. Physicians who smoke are less likely to ask their patients about their smoking behavior or believe their example is likely to influence their patients. Level of perceived preparedness to assist patients to quit smoking was positively associated with knowledge about known health risks associated with smoking. CONCLUSION: Smoking prevalence is high among physicians in the 12 healthcare facilities in Yerevan, and a large percentage of physician smoke in the presence of their patients. Physician smoking behavior and knowledge of smoking related health outcomes in Yerevan influences whether they counsel patients regarding smoking

Road Trauma in Teenage Male Youth with Childhood Disruptive Behavior Disorders: A Population Based Analysis

Donald Redelmeier and colleagues conducted a population-based case-control study of 16-19-year-old males hospitalized for road trauma or appendicitis and showed that disruptive behavior disorders explained a significant amount of road trauma in this group

A new simplified comorbidity score as a prognostic factor in non-small-cell lung cancer patients: description and comparison with the Charlson's index

Treatment of non-small-cell lung cancer (NSCLC) might take into account comorbidities as an important variable. The aim of this study was to generate a new simplified comorbidity score (SCS) and to determine whether or not it improves the possibility of predicting prognosis of NSCLC patients. A two-step methodology was used. Step 1: An SCS was developed and its prognostic value was compared with classical prognostic determinants in the outcome of 735 previously untreated NSCLC patients. Step 2: the SCS reliability as a prognostic determinant was tested in a different population of 136 prospectively accrued NSCLC patients with a formal comparison between SCS and the classical Charlson comorbidity index (CCI). Prognosis was analysed using both univariate and multivariate (Cox model) statistics. The SCS summarised the following variables: tobacco consumption, diabetes mellitus and renal insufficiency (respective weightings 7, 5 and 4), respiratory, neoplastic and cardiovascular comorbidities and alcoholism (weighting=1 for each item). In step 1, aside from classical variables such as age, stage of the disease and performance status, SCS was a statistically significant prognostic variable in univariate analyses. In the Cox model weight loss, stage grouping, performance status and SCS were independent determinants of a poor outcome. There was a trend towards statistical significance for age (P=0.08) and leucocytes count (P=0.06). In Step 2, both SCS and well-known prognostic variables were found as significant determinants in univariate analyses. There was a trend towards a negative prognostic effect for CCI. In multivariate analysis, stage grouping, performance status, histology, leucocytes, lymphocytes, lactate dehydrogenase, CYFRA 21-1 and SCS were independent determinants of a poor prognosis. CCI was removed from the Cox model. In conclusion, the SCS, constructed as an independent prognostic factor in a large NSCLC patient population, is validated in another prospective population and appears more informative than the CCI in predicting NSCLC patient outcome

Purinergic signalling and immune cells

This review article provides a historical perspective on the role of purinergic signalling in the regulation of various subsets of immune cells from early discoveries to current understanding. It is now recognised that adenosine 5'-triphosphate (ATP) and other nucleotides are released from cells following stress or injury. They can act on virtually all subsets of immune cells through a spectrum of P2X ligand-gated ion channels and G protein-coupled P2Y receptors. Furthermore, ATP is rapidly degraded into adenosine by ectonucleotidases such as CD39 and CD73, and adenosine exerts additional regulatory effects through its own receptors. The resulting effect ranges from stimulation to tolerance depending on the amount and time courses of nucleotides released, and the balance between ATP and adenosine. This review identifies the various receptors involved in the different subsets of immune cells and their effects on the function of these cells

Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

Polarization and ideological congruence between parties and supporters in Europe

The relationship between parties and their supporters is central to democracy and ideological representation is among the most important of these linkages. We conduct an investigation of party-supporter congruence in Europe with emphasis on the measurement of ideology and focusing on the role of party system polarization, both as a direct factor in explaining congruence and in modifying the effects of voter sophistication. Understanding this relationship depends in part on how the ideology of parties and supporters is measured. We use Poole’s Blackbox scaling to derive a measure of latent ideology from voter and expert responses to issue scale questions and compare this to a measure based on left–right perceptions. We then examine how variation in the proximity between parties ideological positions and those of their supporters is affected by the polarization of the party system and how this relationship interacts with political sophistication. With the latent ideology measure, we find that polarization decreases party-supporter congruence but increases the effects of respondent education level on congruence. However, we do not find these relationships using the left–right perceptual measure. Our findings underscore important differences between perceptions of left–right labels and the ideological constraint underlying issue positions

Density determination of the thermonuclear fuel region in inertial confinement fusion implosions

Understanding of the thermonuclear burn in an inertial confinement fusion implosion requires knowledge of the local deuterium–tritium (DT) fuel density. Neutron imaging of the core now provides this previously unavailable information. Two types of neutron images are required. The first is an image of the primary 14-MeV neutrons produced by the D + T fusion reaction. The second is an image of the 14-MeV neutrons that leave the implosion hot spot and are downscattered to lower energy by elastic and inelastic collisions in the fuel. These neutrons are measured by gating the detector to record the 6–12 MeV neutrons. Using the reconstructed primary image as a nonuniform source, a set of linear equations is derived that describes the contribution of each voxel of the DT fuel region to a pixel in the downscattered image. Using the measured intensity of the 14-MeV neutrons and downscattered images, the set of equations is solved for the density distribution in the fuel region. The method is validated against test problems and simulations of high-yield implosions. The calculated DT density distribution from one experiment is presented