The multifocal pattern electroretinogram in chloroquine retinopathy

Purpose: Optimal screening for ocular toxicity caused by chloroquine and hydroxychloroquine is still controversial. With the multifocal pattern electroretinogram (mfPERG), a new electrophysiological technique has recently become available to detect early changes of ganglion cells. In this study this new technique is applied to a series of 10 patients seen consecutively receiving long-term chloroquine medication. Methods: In 10 patients receiving chloroquine medication, clinical examination, Amsler visual field testing and computerized color vision testing were performed. If toxicity was suspected, automated perimetry was carried out. In addition, in all patients conventional pattern electroretinogram (PERG) and mfPERG testing were performed. Results: On clinical examination 8 patients showed no chloroquine-associated maculopathy, while 2 patients did. Of these 2, only 1 reported abnormalities when viewing the Amsler chart, while automated perimetry showed typical, ring-like paracentral scotomas in both affected patients and color vision was significantly abnormal. In the normal patients, 4 of 8 had a mild color vision disturbance, which correlated to age-related macular changes. The amplitudes of the PERG and the central (approximately 10degrees) responses of the mfPERG were markedly reduced in chloroquine maculopathy, while the latencies were unchanged. The peripheral rings of mfPERG (ranging to 48degrees) were not affected by chloroquine toxicity. Both PERG and mfPERG were less affected by age-related macular changes. Conclusions: The reduction of PERG and central mfPERG responses in chloroquine maculopathy may help with the early detection of toxicity. Copyright (C) 2004 S. Karger AG, Basel

Experiments in the wild. Introducing the within-person encouragement design

The within-person encouragement design introduced here combines methodological approaches from three research traditions: (a) the analysis of within-person couplings using multilevel models, (b) the experimental manipulation of a treatment variable at the within-person level, and (c) the use of random encouragements as instrumental variables to induce exogenous experimental variation when strict treatment adherence is unrealistic. The proposed combination of these approaches opens up new possibilities to study treatment effects of a broad range of behavioral variables in realistic everyday contexts. We introduce this new research design together with a corresponding data analysis framework: instrumental variable estimation with two-level structural equation models. Using simulations, we show that the approach is applicable with feasible design dimensions regarding numbers of measurement occasions and participants and realistic assumptions about adherence to the encouragement conditions. Possible applications and extensions, as well as potential problems and limitations are discussed. (DIPF/Orig.

Studying within-person variation and within-person couplings in intensive longitudinal data. Lessons learned and to be learned

Intensive longitudinal designs (e.g., experience sampling methods, daily diary studies, or ambulatory assessments) continue to gain importance in sychological aging research. Empirical research using these designs has greatly facilitated our understanding of short-term within-person processes and has started to approach the question how these processes shape long-term development across the life span. The aim of this viewpoint article is to point out four key issues in intensive longitudinal designs that in our opinion require more attention than they are currently given: (a) improvement in measurement reliability, (b) the necessity to investigate inter-individual differences in short-term dynamics, (c) considerations of the time scale across which dynamic effects unfold, and (d) targeting causality by incorporating experimental methods in intensive longitudinal designs. We illustrate these four key issues by referring to a prominent example of within-person dynamics in prior empirical research: the within-person coupling of stressor occurrence and well-being stress reactivity). (DIPF/Orig.

From music making to affective well-being in everyday life. The mediating role of need satisfaction

How music can provide a pathway to affective well-being has mostly been investigated with regard to listening to music or music therapy. Comparatively, less is known about the effects of active music making on well-being in everyday life or its underlying mechanisms. Self-Determination Theory emphasizes the importance of fulfillment of the needs for autonomy, competence, and relatedness for well-being and offers a valuable framework for explaining the postulated link between music making and well-being. In the present daily diary study, 1,042 hobby musicians (age range 13 to 82 years; 65.3% female) completed online assessments of their music making, need fulfillment, and positive and negative affect each day for 10 consecutive days. Results showed that need satisfaction and positive affect were higher, while need dissatisfaction and negative affect were lower on days when participants reported music making. Multilevel structural equation models indicated that the effect of music making on positive affect was mediated by satisfaction of all three needs, with statistically significant indirect effects via autonomy and competence at both the within- and between person level, and relatedness only at the between-person level. There were no statistically significant mediation effects for negative affect. This study is the first to provide evidence for higher affective well-being of hobby musicians on days of music making. Results further suggest satisfaction of basic psychological needs as a mediating mechanism and emphasize the importance to distinguish between indicators of positive functioning (positive affect, need satisfaction) and negative functioning (negative affect, need dissatisfaction). (DIPF/Orig.

Two-channel conduction in YbPtBi

We investigated transport, magnetotransport, and broadband optical properties of the half-Heusler compound YbPtBi. Hall measurements evidence two types of charge carriers: highly mobile electrons with a temperature-dependent concentration and low-mobile holes; their concentration stays almost constant within the investigated temperature range from 2.5 to 300 K. The optical spectra (10 meV - 2.7 eV) can be naturally decomposed into contributions from intra- and interband absorption processes, the former manifesting themselves as two Drude bands with very different scattering rates, corresponding to the charges with different mobilities. These results of the optical measurements allow us to separate the contributions from electrons and holes to the total conductivity and to implement a two-channel-conduction model for description of the magnetotransport data. In this approach, the electron and hole mobilities are found to be around 50000 and 10 cm$^{2}$/Vs at the lowest temperatures (2.5 K), respectively.Comment: 6 page

Vaccine efficacy in swine challenged with a highly virulent S. typhimurium

Vaccination is one of several options to reduce the impact of Salmonella infections in pork. To demonstrate cross protection against infection with S. typhimurium, pigs were vaccinated with a live vaccine (Enterisol SC-54, Boehringer Ingelheim Vetmedica, Inc.), left as positive challenge controls or negative, non challenged controls

Momentary working memory performance is coupled with different dimensions of affect for different children: A mixture model analysis of ambulatory assessment data.

Elementary schoolchildren\u27s working memory performance (WMP) fluctuates from moment to moment and day to day, yet the underlying mechanisms are not well understood. In the present study, affective states were investigated as predictors of these fluctuations. Interindividual differences in the intraindividual affect-WMP associations were expected, and their structure was explored. One hundred nine children (8-11 years) were investigated in an ambulatory assessment. Affective states (positive affect [PA], negative affect [NA], activation, deactivation) and WMP were assessed 3 times daily for up to 31 consecutive days. In the whole sample, WMP was lower at occasions with higher NA or deactivation, while there was no overall effect of PA or activation. Results of a mixture model analysis revealed meaningful heterogeneity in these effects: Approximately half of the children showed comparably weaker effects of affect on WMP, while the other three groups showed (1) comparably stronger negative effects of NA and deactivation; (2) a comparably stronger positive effect of activation; or (3) comparably stronger negative effects of NA and deactivation and stronger positive effects of PA and activation. Findings emphasize the importance of explicitly considering interindividual differences in intraindividual associations. They are discussed in the context of current frameworks of interindividual differences in environmental sensitivity. (DIPF/Orig.

Effects of implicit fear of failure on cognitive processing. A diffusion model analysis

Whereas previous studies suggest that individuals with high implicit fear of failure (FF) perform worse on various indicators of general performance, the underlying mechanisms of this effect have not yet been understood. In our experimental study, 280 participants worked on a binary color discrimination task. Half of the participants were frustrated by means of negative performance feedback, while the control group received mainly positive feedback. We employed a diffusion model analysis (Ratcliff in Psychol Rev 85(2):59-108, 1978) to disentangle the different components involved in the execution of the task. Results revealed that participants in the frustration condition adopted more conservative decision settings (threshold separation parameter of the diffusion model). Besides, high implicit FF was related to slow information accumulation (drift), and this relation was stronger in the frustration condition. Participants with higher FF further showed reduced learning rates during the task. Task related intrusive thoughts are discussed as mechanism for reduced performance of high FF individuals. We conclude that diffusion model analyses can contribute to a better understanding of the mechanisms underlying the effects of psychological motives. (DIPF/Orig.

Presynaptic NMDA Receptors Influence Ca2+ Dynamics by Interacting with Voltage-Dependent Calcium Channels during the Induction of Long-Term Depression.

Spike-timing-dependent long-term depression (t-LTD) of glutamatergic layer (L)4-L2/3 synapses in developing neocortex requires activation of astrocytes by endocannabinoids (eCBs), which release glutamate onto presynaptic NMDA receptors (preNMDARs). The exact function of preNMDARs in this context is still elusive and strongly debated. To elucidate their function, we show that bath application of the eCB 2-arachidonylglycerol (2-AG) induces a preNMDAR-dependent form of chemically induced LTD (eCB-LTD) in L2/3 pyramidal neurons in the juvenile somatosensory cortex of rats. Presynaptic Ca2+ imaging from L4 spiny stellate axons revealed that action potential (AP) evoked Ca2+ transients show a preNMDAR-dependent broadening during eCB-LTD induction. However, blockade of voltage-dependent Ca2+ channels (VDCCs) did not uncover direct preNMDAR-mediated Ca2+ transients in the axon. This suggests that astrocyte-mediated glutamate release onto preNMDARs does not result in a direct Ca2+ influx, but that it instead leads to an indirect interaction with presynaptic VDCCs, boosting axonal Ca2+ influx. These results reveal one of the main remaining missing pieces in the signaling cascade of t-LTD at developing cortical synapses

Assessing how disruption of methanogenic communities and their syntrophic relationships in tidal freshwater marshes via saltwater intrusion may affect CH4 emissions

Tidal freshwater wetlands (TFW), which lie at the interface of saltwater and freshwater ecosystems, are predicted to experience moderate salinity increases due to sea level rise. Increases in salinity generally suppress CH4 production, but it is uncertain to what extent elevated salinity will affect CH4 cycling in TFW. It is also unknown whether CH4 production will resume when freshwater conditions return. The ability to produce CH4 is limited to a monophyletic group of the Euryarchaeota phylum called methanogens (MG), who are limited to a small number of substrates (e.g., acetate, H2, and formate) produced from the breakdown of fermentation products. In freshwater anaerobic soils, the degradation of certain fermentation products (e.g., butyrate, propionate) is only energetically favorable when their catabolic byproduct, H2 or formate, is consumed to low concentrations by MGs. This is considered a form of obligate syntrophy. Sulfate reducing bacteria (SRB) are capable of utilizing a larger variety of substrates than MG, including substrates degraded by methanogenic syntrophy (e.g., butyrate, propionate). The introduction of sulfate (SO4 -2) into TFW via saltwater intrusion events may allow SRB to disrupt syntrophic relationships between hydrogenotrophic MG and syntrophic fermenters. This may select for MG taxa that differ in their rate of CH4 production. The objectives of this study were to determine the effect of oligohaline SO4 -2 concentrations on MG community functions (i.e., CH4 production and syntrophic butyrate degradation); and, to assess whether these functions recover after competition with SRB has been removed