Cytochrome P450s and short-chain dehydrogenases mediate the toxicogenomic response of PCB52 in the nematode Caenorhabditis elegans.

Although non-coplanar PCBs are ubiquitous organic chemicals known to induce numerous biological responses and thus are toxic to man and wildlife, little is known about the toxic mode of action. Using PCB52, an ortho-substituted, 2,2',5,5'-tetrachlorobiphenyl, it was possible to pinpoint the relationship between induced gene expression and observed toxicity in the model nematode Caenorhabditis elegans. On the basis of the calculated EC20 for brood size (5 mg/l), whole genome DNA microarray experiments were performed to identify differentially expressed genes.

Memory-related ERP components for experimentally learned faces and names: characteristics and parallel-test reliabilities.

Previous research with preexperimentally familiar faces and names has identified several memory-related components in the event-related potential (ERP). Here we aimed to characterize these components while controlling the quality of long-term memory with a standardized learning procedure for unfamiliar faces and names. After 1 week, recognition was tested in a repetition priming paradigm.

Impaired self-initiated task preparation during task switching in Parkinson's disease.

Patients with Parkinson's disease (PD) typically show reduced performance in clinical tests involving cognitive control processes, presumably due to reduced availability of dopamine in striatofrontal neuronal circuits. Although task switching paradigms are considered as an ideal experimental measure of cognitive control, previous studies on task switching in PD have yielded ambiguous results, indicating that performance deficits depend on the specific task requirements. Among these, the aspect of self-initiated as opposed to externally triggered task preparation seems to play an important role, as evidenced by recent research.

First passage time densities in resonate-and-fire models.

Motivated by the dynamics of resonant neurons we discuss the properties of the first passage time (FPT) densities for non-Markovian differentiable random processes. We start from an exact expression for the FPT density in terms of an infinite series of integrals over joint densities of level crossings, and consider different approximations based on truncation or on approximate summation of this series. Thus the first few terms of the series give good approximations for the FPT density on short times.

Effects of distributed transmission speeds on propagating activity in neural populations.

Motivated by experimental evidence, a distribution of axonal transmission speeds is introduced into a standard field model of neural populations. The resulting field dynamics is analytically studied by a systematic investigation of the stability and bifurcations of equilibrium solutions. Using a perturbation approach, the effect of distributed speeds on bifurcations of equilibria are determined for general connectivity and speed distributions.

Instruction-induced feature binding.

In order to test whether or not instructions specifying the stimulus-response (S-R) mappings for a new task suffice to create bindings between specified stimulus and response features, we developed a dual task paradigm of the ABBA type in which participants saw new S-R instructions for the A-task in the beginning of each trial. Immediately after the A-task instructions, participants had to perform a logically independent B-task. The imperative stimulus for the A-task was presented after the B-task had been executed.

The influence of task instruction on action coding: constraint setting or direct coding?

In 3 experiments, the authors manipulated response instructions for 2 concurrently performed tasks. Specifically, the authors' instructions described left and right keypresses on a manual task either as left versus right or as blue versus green keypresses and required either "left" versus "right" or "blue" versus "green" concurrent verbalizations. When instructions for responses on the 2 tasks were in terms of location (Experiment 1) or color (Experiments 2a and 2b), then compatible responses on the tasks were faster than incompatible responses.

Semantic processing of unattended meaning is modulated by additional task load: evidence from electrophysiology.

Recently, we observed that the perception of word meaning, as measured with the N400 component of the event-related brain potential, is delayed but unimpaired by various additional tasks when the language task requires the processing of semantic properties of the word stimuli. In the present study, we assessed whether similar effects would be observed when the language task relates to acoustic rather than to semantic properties of the word stimuli. The N400 was elicited by synonymous and non-synonymous spoken noun pairs that were to be classified according to tone pitch.

Absolute pitch and pupillary response: effects of timbre and key color.

The pitch identification performance of absolute pitch possessors has previously been shown to depend on pitch range, key color, and timbre of presented tones. In the present study, the dependence of pitch identification performance on key color and timbre of musical tones was examined by analyzing hit rates, reaction times, and pupillary responses of absolute pitch possessors (n = 9) and nonpossessors (n = 12) during a pitch identification task. Results revealed a significant dependence of pitch identification hit rate but not reaction time on timbre and key color in both groups.

Time's arrow and pupillary response.

The psychological arrow of time refers to our experience of the forward temporal progression of all natural processes. To investigate whether and how time's arrow is mentally coded in individual everyday events, a relatedness judgment task was used. The items each consisted of a verb (probe) and an adjective or participle (target).

Implicit sequence learning in obsessive-compulsive disorder: further support for the fronto-striatal dysfunction model.

Background: Obsessive-compulsive disorder (OCD) is conceived as a disease that implicates dysfunctions in fronto-striatal brain systems. According to this model, performance deficits observed in patients with lesions in these brain areas are hypothesized to be present also in OCD patients. Implicit procedural learning, which refers to the acquisition of motor or nonmotor skills by practice, is one candidate function to test this prediction.

Systemic cardiovascular disease in uremic rats induced by 1,25(OH)2D3.

Objective: Vitamin D may contribute to cardiovascular disease in the absence of hypercalcemia in patients with chronic kidney disease.

Methods: We investigated the effects of long-term (6-week) treatment with 1,25(OH)2D3, at a non-hypercalcemic dosage (0.25 microg/kg per day per orally) in 5/6 nephrectomized rats: (i) vehicle-treated, sham-operated rats; (ii) 1,25(OH)2D3-treated, sham-operated rats; (iii) vehicle-treated, 5/6 nephrectomized rats; and (iv) 1,25(OH)2D3-treated, 5/6 nephrectomized rats.

Neural correlates of intentional and incidental recognition of famous faces.

Event-related potentials (ERPs) were used to study the relationship between intentional and incidental recognition of famous faces. Intentional and incidental recognition were operationally defined as repeated presentations of targets and nontargets within a modified Sternberg task. These repetitions elicited temporally and topographically distinct ERP modulations.

Revisiting proportion estimators.

Proportion estimators are quite frequently used in many application areas. The conventional proportion estimator (number of events divided by sample size) encounters a number of problems when the data are sparse as will be demonstrated in various settings. The problem of estimating its variance when sample sizes become small is rarely addressed in a satisfying framework.

Meta-analysis: a unifying meta-likelihood approach framing unobserved heterogeneity, study covariates, publication bias, and study quality.

Objectives: This contribution provides a unifying concept for meta-analysis integrating the handling of unobserved heterogeneity, study covariates, publication bias and study quality. It is important to consider these issues simultaneously to avoid the occurrence of artifacts, and a method for doing so is suggested here.

Methods: The approach is based upon the meta-likelihood in combination with a general linear nonparametric mixed model, which lays the ground for all inferential conclusions suggested here.

Isolated sarcoid granulomatous interstitial nephritis responding to infliximab therapy.

Sarcoidosis is a systemic disease with multiorgan involvement. In children, renal impairment of sarcoidosis usually is caused by either hypercalcemia leading to nephrocalcinosis or interstitial nephritis with or without granulomata. We report the case of a 13-year-old boy presenting with severe arterial hypertension and acute renal failure caused by an isolated sarcoid granulomatous interstitial nephritis (GIN).

Priming emotional facial expressions as evidenced by event-related brain potentials.

As human faces are important social signals in everyday life, processing of facial affect has recently entered into the focus of neuroscientific research. In the present study, priming of faces showing the same emotional expression was measured with the help of event-related potentials (ERPs) in order to investigate the temporal characteristics of processing facial expressions. Participants classified portraits of unfamiliar persons according to their emotional expression (happy or angry).

Correlates of implicit memory for words and faces in event-related brain potentials.

Prior research has suggested an ERP correlate of implicit memory for words consisting of a centro-parietal positivity around 400 ms. We attempted (1) to replicate this ERP modulation in a different task, involving only trials with correct responses, and (2) to compare the findings to the domain of faces. Two experiments were conducted with a modified Sternberg task, in which both targets and nontargets were presented repeatedly.

Time pressure effects on information processing in overlapping tasks: evidence from the lateralized readiness potential.

Information processing is impaired when two tasks are performed concurrently. The interference between the tasks is commonly attributed to structural bottlenecks or strategic scheduling of information processing. The present experiment investigated the effects of time pressure for the second of two responses on information processing in overlapping tasks by recording the lateralized readiness potential (LRP).

What's special about personally familiar faces? A multimodal approach.

Dual-route models of face recognition suggest separate cognitive and affective routes. The predictions of these models were assessed in recognition tasks with unfamiliar, famous, and personally familiar faces. Whereas larger autonomic responses were only triggered for personally familiar faces, priming effects in reaction times to these faces, presumably reflecting cognitive recognition processes, were equal to those of famous faces.

Is word perception in a second language more vulnerable than in one's native language? Evidence from brain potentials in a dual task setting.

We assessed the effect of additional tasks on language perception in second-language and native speakers. The N400 component of the event-related potential was recorded to spoken nouns that had to be judged for synonymity with a preceding word, while additional choice responses were required to visual stimuli. In both participant groups N400 was delayed as a function of temporal overlap with the additional task.

A prospective study on the course of anxiety after vestibular neuronitis.

Objective: Critical life events trigger intense emotions. Anxiety is one of the most frequent of these emotions. It is unclear which factors determine the intensity and course of anxiety after a critical life event.

Picture-word matching: flexibility in conceptual memory and pupillary responses.

The influence of levels of abstraction in picture-word matching was examined. The items each consisted of one picture and three successively presented words. Hierarchies with words for superordinate, basic, and subordinate level concepts were used (e.

Molecular response of gastrointestinal stromal tumour after treatment with tyrosine kinase inhibitor imatinib mesylate.

Bleeding from the tumour site is not uncommon during the treatment of gastrointestinal stromal tumours with imatinib mesylate. It might represent an early reaction of highly vascularised tumour tissue to receptor blockade. Although often requiring emergency surgery, this is not necessarily a deleterious sign.

A comparison of non-iterative and iterative estimators of heterogeneity variance for the standardized mortality ratio.

This paper continues work presented in Böhning et al. (2002b, Annals of the Institute of Statistical Mathematics 54, 827-839, henceforth BMSRB) where a class of non-iterative estimators of the variance of the heterogeneity distribution for the standardized mortality ratio was discussed. Here, these estimators are further investigated by means of a simulation study.