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Find video protocols related to scientific articles indexed in Pubmed.
The influence of age and mild cognitive impairment on associative memory performance and underlying brain networks.
Brain Imaging Behav
PUBLISHED: 11-10-2014
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Associative memory is essential to everyday activities, such as the binding of faces and corresponding names to form single bits of information. However, this ability often becomes impaired with increasing age. The most important neural substrate of associative memory is the hippocampus, a structure crucially implicated in the pathogenesis of Alzheimer's disease (AD). The main aim of this study was to compare neural correlates of associative memory in healthy aging and mild cognitive impairment (MCI), an at-risk state for AD. We used fMRI to investigate differences in brain activation and connectivity between young controls (n?=?20), elderly controls (n?=?32) and MCI patients (n?=?21) during associative memory retrieval. We observed lower hippocampal activation in MCI patients than control groups during a face-name recognition task, and the magnitude of this decrement was correlated with lower associative memory performance. Further, increased activation in precentral regions in all older adults indicated a stronger involvement of the task positive network (TPN) with age. Finally, functional connectivity analysis revealed a stronger link of hippocampal and striatal components in older adults in comparison to young controls, regardless of memory impairment. In elderly controls, this went hand-in-hand with a stronger activation of striatal areas. Increased TPN activation may be linked to greater reliance on cognitive control in both older groups, while increased functional connectivity between the hippocampus and the striatum may suggest dedifferentiation, especially in elderly controls.
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Evidence-based decision-making in infectious diseases epidemiology, prevention and control: matching research questions to study designs and quality appraisal tools.
BMC Med Res Methodol
PUBLISHED: 05-08-2014
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The Project on a Framework for Rating Evidence in Public Health (PRECEPT) was initiated and is being funded by the European Centre for Disease Prevention and Control (ECDC) to define a methodology for evaluating and grading evidence and strength of recommendations in the field of public health, with emphasis on infectious disease epidemiology, prevention and control. One of the first steps was to review existing quality appraisal tools (QATs) for individual research studies of various designs relevant to this area, using a question-based approach.
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Mentalizing and the Role of the Posterior Superior Temporal Sulcus in Sharing Others' Embarrassment.
Cereb. Cortex
PUBLISHED: 02-13-2014
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The experience of embarrassment provides a highly salient cue for the human moral apparatus. Interestingly, people also experience embarrassment on behalf of others' inappropriate conditions. The perceiver's embarrassment often lacks an equivalent expression of embarrassment in the social counterpart. The present study examines this phenomenon and distinguishes neural circuits involved in embarrassment with and embarrassment for another person's mishaps. Using functional magnetic resonance imaging, we show that the embarrassment on behalf of others engages the temporal pole and the medial prefrontal cortex, central structures of the mentalizing network, together with the anterior insula and anterior cingulate cortex. In contrast, sharing others' embarrassment additionally stimulated the posterior superior temporal sulcus (STS), which exhibited increased functional integration with inferior parietal and insular cortex areas. These findings characterize common neural circuits involved in the embodied representation of embarrassment and further unravel the unique role of the posterior STS in sharing others' affective state.
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Binocular rivalry: frontal activity relates to introspection and action but not to perception.
J. Neurosci.
PUBLISHED: 01-31-2014
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When two dissimilar stimuli are presented to the eyes, perception alternates between multiple interpretations, a phenomenon dubbed binocular rivalry. Numerous recent imaging studies have attempted to unveil neural substrates underlying multistable perception. However, these studies had a conceptual constraint: access to observers' perceptual state relied on their introspection and active report. Here, we investigated to what extent neural correlates of binocular rivalry in healthy humans are confounded by this subjective measure and by action. We used the optokinetic nystagmus and pupil size to objectively and continuously map perceptual alternations for binocular-rivalry stimuli. Combining these two measures with fMRI allowed us to assess the neural correlates of binocular rivalry time locked to the perceptual alternations in the absence of active report. When observers were asked to actively report their percept, our objective measures matched the report. In this active condition, objective measures and subjective reporting revealed that occipital, parietal, and frontal areas underlie the processing of binocular rivalry, replicating earlier findings. Furthermore, objective measures provided additional statistical power due to their continuous nature. Importantly, when observers passively experienced rivalry without reporting perceptual alternations, a different picture emerged: differential neural activity in frontal areas was absent, whereas activation in occipital and parietal regions persisted. Our results question the popular view of a driving role of frontal areas in the initiation of perceptual alternations during binocular rivalry. Instead, we conclude that frontal areas are associated with active report and introspection rather than with rivalry per se.
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The role and utilisation of public health evaluations in Europe: a case study of national hand hygiene campaigns.
BMC Public Health
PUBLISHED: 01-27-2014
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Evaluations are essential to judge the success of public health programmes. In Europe, the proportion of public health programmes that undergo evaluation remains unclear. The European Centre for Disease Prevention and Control sought to determine the frequency of evaluations amongst European national public health programmes by using national hand hygiene campaigns as an example of intervention.
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Neural correlates of procedural variants in cognitive-behavioral therapy: a randomized, controlled multicenter FMRI study.
Psychother Psychosom
PUBLISHED: 01-19-2014
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Cognitive behavioral therapy (CBT) is an effective treatment for panic disorder with agoraphobia (PD/AG). It is unknown, how variants of CBT differentially modulate brain networks involved in PD/AG. This study was aimed to evaluate the effects of therapist-guided (T+) versus self-guided (T-) exposure on the neural correlates of fear conditioning in PD/AG.
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The issue of mandatory vaccination for healthcare workers in Europe.
Expert Rev Vaccines
PUBLISHED: 12-18-2013
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Mandatory policies have occasionally been implemented, targeting optimal vaccination uptake among healthcare workers (HCWs). Herein, we analyze the existing recommendations in European countries and discuss the feasibility of implementing mandatory vaccination for HCWs. As reflected by a survey among vaccine experts from 29 European countries, guidelines on HCW vaccination were issued in all countries, though with substantial differences in targeted diseases, HCW groups and type of recommendation. Mandatory policies were only exceptionally implemented. Results from a second survey suggested that such policies would not become easily adopted, and recommendations might work better if focusing on specific HCW groups and appropriate diseases such as hepatitis B, influenza and measles. In conclusion, guidelines for HCW vaccination, but not mandatory policies, are widely adopted in Europe. Recommendations targeting specific HCW groups and diseases might be better accepted and facilitate higher vaccine uptake than policies vaguely targeting all HCW groups.
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Neural substrates of treatment response to cognitive-behavioral therapy in panic disorder with agoraphobia.
Am J Psychiatry
PUBLISHED: 08-29-2013
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Although exposure-based cognitive-behavioral therapy (CBT) is an effective treatment option for panic disorder with agoraphobia, the neural substrates of treatment response remain unknown. Evidence suggests that panic disorder with agoraphobia is characterized by dysfunctional safety signal processing. Using fear conditioning as a neurofunctional probe, the authors investigated neural baseline characteristics and neuroplastic changes after CBT that were associated with treatment outcome in patients with panic disorder with agoraphobia.
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Potential bias in meta-analyses of effect sizes in imaging genetics.
Schizophr Bull
PUBLISHED: 03-09-2013
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The penetrance of genetic variation has been assumed to be higher at the level of neural phenotypes than at the level of behavioral phenotypes. One of the few attempts to validate this assumption is the study of Rose and Donohoe published in this issue. In this article, we will address 2 methodological issues we believe have to be considered for a better understanding of the present results. We briefly discuss potential solutions that might also help improve future meta-analyses of effect sizes in neuroimaging data.
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Association of rs1006737 in CACNA1C with alterations in prefrontal activation and fronto-hippocampal connectivity.
Hum Brain Mapp
PUBLISHED: 02-13-2013
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Background: Genome-wide association studies have identified the rs1006737 single nucleotide polymorphism (SNP) in the CACNA1C gene as a susceptibility locus for schizophrenia and bipolar disorder. On the neural systems level this association is explained by altered functioning of the dorsolateral prefrontal cortex (DLPFC) and the hippocampal formation (HF), brain regions also affected by mental illness. In the present study we investigated the association of rs1006737 genotype with prefrontal activation and fronto-hippocampal connectivity. Methods: We used functional magnetic resonance imaging to measure neural activation during an n-back working memory task in 94 healthy subjects. All subjects were genotyped for the SNP rs1006737. We tested associations of the rs1006737 genotype with changes in working-memory-related DLPFC activation and functional integration using a seed region functional connectivity approach. Results: Rs1006737 genotype was associated with altered right-hemispheric DLPFC activation. The homozygous A (risk) group showed decreased activation compared to G-allele carriers. Further, the functional connectivity analysis revealed a positive association of fronto-hippocampal connectivity with rs1006737 A alleles. Conclusions: We did not replicate the previous findings of increased right DLPFC activation in CACNA1C rs1006737 A homozygotes. In fact, we found the opposite effect, thus questioning prefrontal inefficiency as rs1006737 genotype-related intermediate phenotype. On the other hand, our results indicate that alterations in the functional coupling between the prefrontal cortex and the medial temporal lobe could represent a neural system phenotype that is mediated by CACNA1C rs1006737 and other genetic susceptibility loci for schizophrenia and bipolar disorder. Hum Brain Mapp, 2013. © 2013 Wiley Periodicals, Inc.
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Test-Retest Reliability of fMRI Brain Activity during Memory Encoding.
Front Psychiatry
PUBLISHED: 01-01-2013
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The mechanisms underlying hemispheric specialization of memory are not completely understood. Functional magnetic resonance imaging (fMRI) can be used to develop and test models of hemispheric specialization. In particular for memory tasks however, the interpretation of fMRI results is often hampered by the low reliability of the data. In the present study we therefore analyzed the test-retest reliability of fMRI brain activation related to an implicit memory encoding task, with a particular focus on brain activity of the medial temporal lobe (MTL). Fifteen healthy subjects were scanned with fMRI on two sessions (average retest interval 35?days) using a commonly applied novelty encoding paradigm contrasting known and unknown stimuli. To assess brain lateralization, we used three different stimuli classes that differed in their verbalizability (words, scenes, fractals). Test-retest reliability of fMRI brain activation was assessed by an intraclass-correlation coefficient (ICC), describing the stability of inter-individual differences in the brain activation magnitude over time. We found as expected a left-lateralized brain activation network for the words paradigm, a bilateral network for the scenes paradigm, and predominantly right-hemispheric brain activation for the fractals paradigm. Although these networks were consistently activated in both sessions on the group level, across-subject reliabilities were only poor to fair (ICCs???0.45). Overall, the highest ICC values were obtained for the scenes paradigm, but only in strongly activated brain regions. In particular the reliability of brain activity of the MTL was poor for all paradigms. In conclusion, for novelty encoding paradigms the interpretation of fMRI results on a single subject level is hampered by its low reliability. More studies are needed to optimize the retest reliability of fMRI activation for memory tasks.
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MRI phantoms - are there alternatives to agar?
PLoS ONE
PUBLISHED: 01-01-2013
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The suitability of different gelling agents as MRI phantoms was evaluated in terms of homogeneity, gel stability and reproducibility. Time and effort for preparation were also taken into account. The relaxation times of various gel compositions were estimated. Carbomer-980 and Carbopol-974P were determined to be promising novel phantom materials. These gelling agents are readily available, inexpensive and easy to handle given that thermal treatment is not required. Furthermore, the viscoelasticity of their polymer network is pH-dependent. With such characteristics, it was even possible to embed sensitive objects and retrieve them after testing. This was demonstrated with a fiber phantom for Diffusion Weighted MRI applications. Since Carbomer-980 and Carbopol-974P are non-hazardous, they are also suitable for multimodal setups (e.g., MRI as well as ultrasonic imaging).
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Space-time modelling of the spread of salmon lice between and within Norwegian marine salmon farms.
PLoS ONE
PUBLISHED: 01-01-2013
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Parasitic salmon lice are potentially harmful to salmonid hosts and farm produced lice pose a threat to wild salmonids. To control salmon lice infections in Norwegian salmonid farming, numbers of lice are regularly counted and lice abundance is reported from all salmonid farms every month. We have developed a stochastic space-time model where monthly lice abundance is modelled simultaneously for all farms. The set of farms is regarded as a network where the degree of contact between farms depends on their seaway distance. The expected lice abundance at each farm is modelled as a function of i) lice abundance in previous months at the same farm, ii) at neighbourhood farms, and iii) other, unspecified sources. In addition, the model includes explanatory variables such as seawater temperature and farm-numbers of fish. The model gives insight into factors that affect salmon lice abundance and contributing sources of infection. New findings in this study were that 66% of the expected salmon lice abundance was attributed to infection within farms, 28% was attributed to infection from neighbourhood farms and 6% to non-specified sources of infection. Furthermore, we present the relative risk of infection between neighbourhood farms as a function of seaway distance, which can be viewed as a between farm transmission kernel for salmon lice. The present modelling framework lays the foundation for development of future scenario simulation tools for examining the spread and abundance of salmon lice on farmed salmonids under different control regimes.
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High frequency of Tropheryma whipplei in culture-negative endocarditis.
J. Clin. Microbiol.
PUBLISHED: 11-30-2011
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"Classical" Whipples disease (cWD) is caused by Tropheryma whipplei and is characterized by arthropathy, weight loss, and diarrhea. T. whipplei infectious endocarditis (TWIE) is rarely reported, either in the context of cWD or as isolated TWIE without signs of systemic infection. The frequency of TWIE is unknown, and systematic studies are lacking. Here, we performed an observational cohort study on the incidence of T. whipplei infection in explanted heart valves in two German university centers. Cardiac valves from 1,135 patients were analyzed for bacterial infection using conventional culture techniques, PCR amplification of the bacterial 16S rRNA gene, and subsequent sequencing. T. whipplei-positive heart valves were confirmed by specific PCR, fluorescence in situ hybridization, immunohistochemistry, histological examination, and culture for T. whipplei. Bacterial endocarditis was diagnosed in 255 patients, with streptococci, staphylococci, and enterococci being the main pathogens. T. whipplei was the fourth most frequent pathogen, found in 16 (6.3%) cases, and clearly outnumbered Bartonella quintana, Coxiella burnetii, and members of the HACEK group (Haemophilus species, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae). In this cohort, T. whipplei was the most commonly found pathogen associated with culture-negative infective endocarditis.
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The effect of neurogranin on neural correlates of episodic memory encoding and retrieval.
Schizophr Bull
PUBLISHED: 07-28-2011
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Neurogranin (NRGN) is the main postsynaptic protein regulating the availability of calmodulin-Ca(2+) in neurons. NRGN is expressed exclusively in the brain, particularly in dendritic spines and has been implicated in spatial learning and hippocampal plasticity. Genetic variation in rs12807809 in the NRGN gene has recently been confirmed to be associated with schizophrenia in a meta-analysis of genome-wide association studies: the T-allele was found to be genome-wide significantly associated with schizophrenia. Cognitive tests and personality questionnaires were administered in a large sample of healthy subjects. Brain activation was measured with functional magnetic resonance imaging (fMRI) during an episodic memory encoding and retrieval task in a subsample. All subjects were genotyped for NRGN rs12807809. There was no effect of genotype on personality or cognitive measures in the large sample. Homozygote carriers of the T-allele showed better performance in the retrieval task during fMRI. After controlling for memory performance, differential brain activation was evident in the anterior cingulate cortex for the encoding and posterior cingulate regions during retrieval. We could demonstrate that rs12807809 of NRGN is associated with differential neural functioning in the anterior and posterior cingulate. These areas are involved in episodic memory processes and have been implicated in the pathophysiology of schizophrenia in structural and functional imaging as well as postmortem studies.
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Functional connectivity analyses in imaging genetics: considerations on methods and data interpretation.
PLoS ONE
PUBLISHED: 06-21-2011
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Functional magnetic resonance imaging (fMRI) can be combined with genotype assessment to identify brain systems that mediate genetic vulnerability to mental disorders ("imaging genetics"). A data analysis approach that is widely applied is "functional connectivity". In this approach, the temporal correlation between the fMRI signal from a pre-defined brain region (the so-called "seed point") and other brain voxels is determined. In this technical note, we show how the choice of freely selectable data analysis parameters strongly influences the assessment of the genetic modulation of connectivity features. In our data analysis we exemplarily focus on three methodological parameters: (i) seed voxel selection, (ii) noise reduction algorithms, and (iii) use of additional second level covariates. Our results show that even small variations in the implementation of a functional connectivity analysis can have an impact on the connectivity pattern that is as strong as the potential modulation by genetic allele variants. Some effects of genetic variation can only be found for one specific implementation of the connectivity analysis. A reoccurring difficulty in the field of psychiatric genetics is the non-replication of initially promising findings, partly caused by the small effects of single genes. The replication of imaging genetic results is therefore crucial for the long-term assessment of genetic effects on neural connectivity parameters. For a meaningful comparison of imaging genetics studies however, it is therefore necessary to provide more details on specific methodological parameters (e.g., seed voxel distribution) and to give information how robust effects are across the choice of methodological parameters.
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Partial support for ZNF804A genotype-dependent alterations in prefrontal connectivity.
Hum Brain Mapp
PUBLISHED: 05-05-2011
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Genome-wide association studies identified the single nucleotide polymorphism rs1344706 in ZNF804A as a common risk-variant for schizophrenia and bipolar disorder. Whereas the molecular function of ZNF804A is yet unclear, recent imaging genetics studies have started to characterize the neural systems architecture linking rs1344706 genotype to psychosis. Carring rs1344706 risk-alleles was associated with a decrease in functional connectivity within the dorsolateral prefrontal cortices (DLPFCs) as well as an increase in connectivity between the DLPFC and the hippocampal formation (HF) in the context of a working memory task. The present study aimed at replicating these findings in an independent sample of 94 healthy subjects. Subjects were genotyped for rs1344706 and performed a working memory task during functional magnetic resonance imaging. Results indicate no support for a decrease of functional coupling between the bilateral DLPFCs at higher ZNF804A risk status. However, the current data show the previously described alteration in functional coupling between the right DLPFC and the HFs, albeit with weaker effects. Decoupled by default, the functional connectivity between the right DLPFC and anterior HFs increased with the number of rs1344706 risk alleles. The present data support fronto-hippocampal dysconnectivity as intermediate phenotype linking rs1344706 genotype to psychosis. We discuss the issues in replicating the interhemispheric DLPFC coupling in light of the effect sizes rs1344706 genotype has on brain function, concluding that further independent replication studies are fundamentally needed to ascertain the role of rs1344706 in the functional integration of neural systems.
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Your flaws are my pain: linking empathy to vicarious embarrassment.
PLoS ONE
PUBLISHED: 03-15-2011
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People vicariously experience embarrassment when observing others public pratfalls or etiquette violations. In two consecutive studies we investigated the subjective experience and the neural correlates of vicarious embarrassment for others in a broad range of situations. We demonstrated, first, that vicarious embarrassment was experienced regardless of whether the observed protagonist acted accidentally or intentionally and was aware or unaware that he/she was in an embarrassing situation. Second, using functional magnetic resonance imaging (fMRI), we showed that the anterior cingulate cortex and the left anterior insula, two cortical structures typically involved in vicarious feelings of others pain, are also strongly implicated in experiencing the social pain for others flaws and pratfalls. This holds true even for situations that engage protagonists not aware of their current predicament. Importantly, the activity in the anterior cingulate cortex and the left anterior insula positively correlated with individual differences in trait empathy. The present findings establish the empathic process as a fundamental prerequisite for vicarious embarrassment experiences, thus connecting affect and cognition to interpersonal processes."When we are living with people who have a delicate sense of propriety, we are in misery on their account when anything unbecoming is committed. So I always feel for and with Charlotte when a person is tipping his chair. She cannot endure it." [Elective Affinities, J. W. Goethe].
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Latencies in BOLD response during visual attention processes.
Brain Res.
PUBLISHED: 02-09-2011
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One well-investigated division of attentional processes focuses on alerting, orienting and executive control, which can be assessed applying the attentional network test (ANT). The goal of the present study was to add further knowledge about the temporal dynamics of relevant neural correlates. As a right hemispheric dominance for alerting and orienting has previously been reported for intrinsic but not for phasic alertness, we additionally addressed a potential impact of this lateralization of attention by employing a lateralized version of the ANT, capturing phasic alertness processes. Sixteen healthy subjects underwent event-related functional magnetic resonance imaging (fMRI) while performing the ANT. Analyses of BOLD magnitude replicated the engagement of a fronto-parietal network in the attentional subsystems. The amplitudes of the attentional contrasts interacted with visual field presentation in the sense that the thalamus revealed a greater involvement for spatially cued items presented in the left visual field. Comparisons of BOLD latencies in visual cortices, first, verified faster BOLD responses following contra-lateral stimulus presentation. Second and more importantly, we identified attention-modulated activation in secondary visual and anterior cingulate cortices. Results are discussed in terms of bottom-up and lateralization processes. Although intrinsic and phasic alertness are distinct cognitive processes, we propose that neural substrates of intrinsic alertness may be accessed by phasic alertness provided that the attention-dominant (i.e., the right) hemisphere is activated directly by a warning stimulus.
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Avian influenza virus risk assessment in falconry.
Virol. J.
PUBLISHED: 02-08-2011
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There is a continuing threat of human infections with avian influenza viruses (AIV). In this regard falconers might be a potential risk group because they have close contact to their hunting birds (raptors such as falcons and hawks) as well as their avian prey such as gulls and ducks. Both (hunting birds and prey birds) seem to be highly susceptible to some AIV strains, especially H5N1. We therefore conducted a field study to investigate AIV infections in falconers, their falconry birds as well as prey birds.
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The immune reconstitution inflammatory syndrome in whipple disease: a cohort study.
Ann. Intern. Med.
PUBLISHED: 12-08-2010
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Whipple disease, which is caused by infection with Tropheryma whipplei, can be treated effectively with antimicrobials. Occasionally, inflammation reappears after initial improvement; this is often interpreted as refractory or recurrent disease. However, polymerase chain reaction for T. whipplei in tissue is sometimes negative during reinflammation, indicating absence of vital bacteria, and this reinflammation does not respond to antimicrobials but does respond to steroids.
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[Emergence of clostridium difficile ribotype 027 in Germany: epidemiological and clinical characteristics].
Z Gastroenterol
PUBLISHED: 09-13-2010
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In September 2007 an increase of severe Clostridium difficile-associated infections (CDI) was noticed in a hospital in the city of Trier, Germany. It was assumed that a new, possibly hypervirulent strain (PCR ribotype 027) was related to these events. An outbreak investigation was initiated by the local health authorities and the Robert Koch Institute to describe the epidemiology of the possible outbreak and to identify and control the possible sources.
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Outbreak of leptospirosis among triathlon participants in Germany, 2006.
BMC Infect. Dis.
PUBLISHED: 04-10-2010
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In August 2006, a case of leptospirosis occurred in an athlete after a triathlon held around Heidelberg and in the Neckar river. In order to study a possible outbreak and to determine risk factors for infection an epidemiological investigation was performed.
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The effects of a DTNBP1 gene variant on attention networks: an fMRI study.
Behav Brain Funct
PUBLISHED: 03-29-2010
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Attention deficits belong to the main cognitive symptoms of schizophrenia and come along with altered neural activity in previously described cerebral networks. Given the high heritability of schizophrenia the question arises if impaired function of these networks is modulated by susceptibility genes and detectable in healthy risk allele carriers.
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Neural correlates of aversive conditioning: development of a functional imaging paradigm for the investigation of anxiety disorders.
Eur Arch Psychiatry Clin Neurosci
PUBLISHED: 01-11-2010
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The purpose of the present study was to establish a short paradigm for the examination of classical aversive conditioning processes for application in patients with anxiety disorders. We measured behavioral, autonomic and neural correlates of the paradigm in healthy subjects, applying functional magnetic resonance imaging (fMRI) and measurement of skin conductance. Therefore, neutral visual stimuli were paired with an unpleasant white noise as unconditioned stimulus. Twenty healthy subjects performed three experimental phases of learning: familiarization, acquisition and extinction. Subjective ratings of valence and arousal after each phase of conditioning as well as skin conductance measurement indicated successful conditioning. During acquisition, fMRI results showed increased activation for the conditioned stimulus (CS+(unpaired)) when compared with the non-conditioned stimulus (CS-) in the right amygdala, the insulae, the anterior cingulate cortex and the parahippocampal gyrus, all regions known to be involved in emotional processing. In addition, a linearly decreasing activation in the right amygdala/hippocampus for the CS- across the acquisition phase was found. There were no significant differences between CS+ and CS- during extinction. In conclusion, the applicability of this paradigm for the evaluation of neural correlates in conditioning and extinction processes has been proven. Thus, we present a promising paradigm for the examination of the fear-circuit in patients with anxiety disorders and additionally effects of cognitive-behavioral interventions.
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COMT genotype and its role on hippocampal-prefrontal regions in declarative memory.
Neuroimage
PUBLISHED: 01-11-2010
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Memory dysfunction is a prominent feature in schizophrenia. Impairments of declarative memory have been consistently linked to alterations especially within hippocampal-prefrontal regions. Due to the high heritability of schizophrenia, susceptibility genes and their modulatory impact on the neural correlates on memory are of major relevance. In the present study the influence of the COMT val(158)met status on the neural correlates of declarative memory was investigated in healthy subjects.
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The effect of G72 genotype on neural correlates of memory encoding and retrieval.
Neuroimage
PUBLISHED: 08-31-2009
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Polymorphisms in the G72 (also named d-amino acid oxidase activator, DAOA) gene increase the vulnerability for schizophrenia and affective psychosis. Three recent genetic neuroimaging studies showed that variation in G72 influences the brain activity in the medial temporal lobe (MTL), supporting the hypothesis that G72 might play a modulatory role on brain activity in MTL structures. In the present study we therefore investigated the effect of G72 on the neural correlates of long-term memory encoding and retrieval in a large sample of healthy subjects (n=83) using functional magnetic resonance imaging. A face encoding and a face retrieval memory task were chosen because on the one hand they specifically activate MTL structures and on the other hand they tap into memory processes that are compromised in patients with schizophrenia and affective disorder. Despite a strong a-priori hypothesis of genotype group activation differences in the MTL along with a large sample size we did neither find an effect of G72 genotype status on brain activity in the MTL nor in any other brain regions. The present data therefore do not support the view of a general modulatory role of G72 on MTL brain activity, at least not in the domain of long-term memory encoding and retrieval. Our results highlight the importance of replication studies in genetic neuroimaging.
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The effect of Neuregulin 1 on neural correlates of episodic memory encoding and retrieval.
Neuroimage
PUBLISHED: 07-14-2009
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Neuregulin 1 (NRG1) has been found to be associated with schizophrenia. Impaired performance in episodic memory tasks is an often replicated finding in this disorder. In functional neuroimaging studies, this dysfunction has been linked to signal changes in prefrontal and medial temporal areas. Therefore, it is of interest whether genes associated with the disorder, such as NRG1, modulate episodic memory performance and its neural correlates. Ninety-four healthy individuals performed an episodic memory encoding and a retrieval task while brain activation was measured with functional MRI. All subjects were genotyped for the single nucleotide polymorphism (SNP) rs35753505 in the NRG1 gene. The effect of genotype on brain activation was assessed with fMRI during the two tasks. While there were no differences in performance, brain activation in the cingulate gyrus (BA 24), the left middle frontal gyrus (BA 9), the bilateral fusiform gyrus and the left middle occipital gyrus (BA 19) was positively correlated with the number of risk alleles in NRG1 during encoding. During retrieval brain activation was positively correlated with the number of risk alleles in the left middle occipital gyrus (BA 19). NRG1 genotype does modulate brain activation during episodic memory processing in key areas for memory encoding and retrieval. The results suggest that subjects with risk alleles show hyperactivations in areas associated with elaborate encoding strategies.
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Effect of CACNA1C rs1006737 on neural correlates of verbal fluency in healthy individuals.
Neuroimage
PUBLISHED: 07-08-2009
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Recent genetic studies found the A allele of the variant rs1006737 in the alpha 1C subunit of the L-type voltage-gated calcium channel (CACNA1C) gene to be overrepresented in patients suffering from bipolar disorder, schizophrenia or major depression. While the functions underlying the pathophysiology of these psychiatric disorders are yet unknown, impaired performance in verbal fluency tasks is an often replicated finding. We investigated the influence of the rs1006737 single nucleotide polymorphism (SNP) on verbal fluency and its neural correlates.
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Social cues, mentalizing and the neural processing of speech accompanied by gestures.
Neuropsychologia
PUBLISHED: 06-17-2009
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Body orientation and eye gaze influence how information is conveyed during face-to-face communication. However, the neural pathways underpinning the comprehension of social cues in everyday interaction are not known. In this study we investigated the influence of addressing vs. non-addressing body orientation on the neural processing of speech accompanied by gestures. While in an fMRI scanner, participants viewed short video clips of an actor speaking sentences with object- (O; e.g., shape) or person-related content (P; e.g., saying goodbye) accompanied by iconic (e.g., circle) or emblematic gestures (e.g., waving), respectively. The actors body was oriented either toward the participant (frontal, F) or toward a third person (lateral, L) not visible. For frontal vs. lateral actor orientation (F>L), we observed activation of bilateral occipital, inferior frontal, medial frontal, right anterior temporal and left parietal brain regions. Additionally, we observed activity in the occipital and anterior temporal lobes due to an interaction effect between actor orientation and content of the communication (PF>PL)>(OF>OL). Our findings indicate that social cues influence the neural processing of speech-gesture utterances. Mentalizing (the process of inferring the mental state of another individual) could be responsible for these effects. In particular, socially relevant cues seem to activate regions of the anterior temporal lobes if abstract person-related content is communicated by speech and gesture. These new findings illustrate the complexity of interpersonal communication, as our data demonstrate that multisensory information pathways interact at both perceptual and semantic levels.
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Structural correlates of functional language dominance: a voxel-based morphometry study.
J Neuroimaging
PUBLISHED: 05-07-2009
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The goal of this study was to explore the structural correlates of functional language dominance by directly comparing the brain morphology of healthy subjects with left- and right-hemisphere language dominance.
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Neural integration of iconic and unrelated coverbal gestures: a functional MRI study.
Hum Brain Mapp
PUBLISHED: 04-08-2009
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Gestures are an important part of interpersonal communication, for example by illustrating physical properties of speech contents (e.g., "the ball is round"). The meaning of these so-called iconic gestures is strongly intertwined with speech. We investigated the neural correlates of the semantic integration for verbal and gestural information. Participants watched short videos of five speech and gesture conditions performed by an actor, including variation of language (familiar German vs. unfamiliar Russian), variation of gesture (iconic vs. unrelated), as well as isolated familiar language, while brain activation was measured using functional magnetic resonance imaging. For familiar speech with either of both gesture types contrasted to Russian speech-gesture pairs, activation increases were observed at the left temporo-occipital junction. Apart from this shared location, speech with iconic gestures exclusively engaged left occipital areas, whereas speech with unrelated gestures activated bilateral parietal and posterior temporal regions. Our results demonstrate that the processing of speech with speech-related versus speech-unrelated gestures occurs in two distinct but partly overlapping networks. The distinct processing streams (visual versus linguistic/spatial) are interpreted in terms of "auxiliary systems" allowing the integration of speech and gesture in the left temporo-occipital region.
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The effect of the COMT val(158)met polymorphism on neural correlates of semantic verbal fluency.
Eur Arch Psychiatry Clin Neurosci
PUBLISHED: 03-31-2009
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Variation in the val(158)met polymorphism of the COMT gene has been found to be associated with cognitive performance. In functional neuroimaging studies, this dysfunction has been linked to signal changes in prefrontal areas. Given the complex modulation and functional heterogeneity of frontal lobe systems, further specification of COMT gene-related phenotypes differing in prefrontally mediated cognitive performance are of major interest. Eighty healthy individuals (54 men, 26 women; mean age 23.3 years) performed an overt semantic verbal fluency task while brain activation was measured with functional magnetic resonance imaging (fMRI). COMT val(158)met genotype was determined and correlated with brain activation measured with fMRI during the task. Although there were no differences in performance, brain activation in the left inferior frontal gyrus [Brodmann area 10] was positively correlated with the number of val alleles in the COMT gene. COMT val(158)met status modulates brain activation during the language production on a semantic level in an area related to executive functions.
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Effect of the G72 (DAOA) putative risk haplotype on cognitive functions in healthy subjects.
BMC Psychiatry
PUBLISHED: 03-10-2009
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In the last years, several susceptibility genes for psychiatric disorders have been identified, among others G72 (also named D-amino acid oxidase activator, DAOA). Typically, the high-risk variant of a vulnerability gene is associated with decreased cognitive functions already in healthy individuals. In a recent study however, a positive effect of the high-risk variant of G72 on verbal working memory was reported. In the present study, we therefore examined the relationship between G72 genotype status and a broad range of cognitive functions in 423 healthy individuals.
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Assessment of verbal memory by fMRI: lateralization and functional neuroanatomy.
Clin Neurol Neurosurg
PUBLISHED: 02-20-2009
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The medial temporal lobe (MTL) is essential for declarative memory formation, but also a frequent source of seizures. To decrease the risk of amnestic impairments after temporal lobectomy, functional magnetic resonance imaging (fMRI) is increasingly used to establish pre-operative measures for a prognosis of postoperative memory performance. The present study addresses one of the major challenges in clinical fMRI, the interpretation of activation pattern in single subjects. Before investigating patients however, it must be first assessed to which extent the verbal memory paradigm can be used to determine the lateralization and the functional neuroanatomy of MTL-activity. Therefore, this study took a "step backwards" by first examining healthy subjects without known MTL pathology.
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Detection of hepatitis E virus in wild boars of rural and urban regions in Germany and whole genome characterization of an endemic strain.
Virol. J.
PUBLISHED: 02-16-2009
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Hepatitis E is an increasingly diagnosed human disease in Central Europe. Besides domestic pigs, in which hepatitis E virus (HEV) infection is highly prevalent, wild boars have been identified as a possible source of human infection. In order to assess the distribution of HEV in the wild boar population of Germany, we tested liver samples originating from different geographical regions for the presence of the HEV genome and compared the detected sequences to animal and human HEV strains.
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Risk factors related to a hospital-associated cluster of Clostridium difficile PCR ribotype 027 infections in Germany During 2007.
Infect Control Hosp Epidemiol
PUBLISHED: 02-14-2009
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In 2007, Clostridium difficile polymerase chain reaction (PCR) ribotype 027 emerged in Germany. We conducted a hospital-based case-control study to identify specific risk factors for infection with this strain. Logistic regression analysis involving 15 case patients and 31 control patients revealed that exposure to fluoroquinolones (matched odds ratio, 36.2; P < .01) or cephalosporins (matched odds ratio, 19.1; P < .01) was independently related to C. difficile PCR ribotype 027 infection.
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Resurgence of field fever in a temperate country: an epidemic of leptospirosis among seasonal strawberry harvesters in Germany in 2007.
Clin. Infect. Dis.
PUBLISHED: 02-06-2009
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Although leptospirosis is a reemerging zoonosis of global importance, outbreaks related to agricultural exposures are primarily situated in tropical countries. In July 2007, a suspected leptospirosis outbreak was recognized among strawberry harvesters from Eastern Europe who were working in Germany. An investigation was initiated to identify the outbreak source and the risk factors for infection.
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A putative high risk diplotype of the G72 gene is in healthy individuals associated with better performance in working memory functions and altered brain activity in the medial temporal lobe.
Neuroimage
PUBLISHED: 01-08-2009
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G72 is a vulnerability gene for schizophrenia and affective psychosis, disorders that are characterized by deficits in working memory. In the present study we investigated whether the G72 genotype influences verbal and spatial working memory functions in healthy individuals. Working memory was assessed at the behavioural level in 423 subjects using the spatial span of the Wechsler Memory Scale (spatial working memory) and the letter-number-span test (verbal working memory). In a sub-sample of 83 subjects, we assessed working memory functions also at the neural level using functional magnetic resonance imaging during a classical letter variant of the n-back task. Unexpectedly the high risk allele carriers performed better in the verbal working memory task than the other subjects. These behavioural differences were accompanied by brain activation differences in the right parahippocampus, a brain region that plays a major role in schizophrenia and affective disorders. The high risk variant of a vulnerability gene therefore does not necessarily have to negatively affect cognitive abilities per se, but may even have beneficial effects on cognitive functions in the non-affected population.
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Age-related changes in parietal lobe activation during an episodic memory retrieval task.
J Neural Transm
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The crucial role of lateral parietal regions in episodic memory has been confirmed in previous studies. While aging has an influence on retrieval of episodic memory, it remains to be examined how the involvement of lateral parietal regions in episodic memory changes with age. We investigated episodic memory retrieval in two age groups, using faces as stimuli and retrieval success as a measure of episodic memory. Young and elderly participants showed activation within a similar network, including lateral and medial parietal as well as prefrontal regions, but elderly showed a higher level of brain activation regardless of condition. Furthermore, we examined functional connectivity in the two age groups and found a more extensive network in the young group, including correlations of parietal and prefrontal regions. In the elderly, the overall stronger activation related to memory performance may indicate a compensatory process for a less extensive functional network.
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Accuracy and reliability of automated gray matter segmentation pathways on real and simulated structural magnetic resonance images of the human brain.
PLoS ONE
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Automated gray matter segmentation of magnetic resonance imaging data is essential for morphometric analyses of the brain, particularly when large sample sizes are investigated. However, although detection of small structural brain differences may fundamentally depend on the method used, both accuracy and reliability of different automated segmentation algorithms have rarely been compared. Here, performance of the segmentation algorithms provided by SPM8, VBM8, FSL and FreeSurfer was quantified on simulated and real magnetic resonance imaging data. First, accuracy was assessed by comparing segmentations of twenty simulated and 18 real T1 images with corresponding ground truth images. Second, reliability was determined in ten T1 images from the same subject and in ten T1 images of different subjects scanned twice. Third, the impact of preprocessing steps on segmentation accuracy was investigated. VBM8 showed a very high accuracy and a very high reliability. FSL achieved the highest accuracy but demonstrated poor reliability and FreeSurfer showed the lowest accuracy, but high reliability. An universally valid recommendation on how to implement morphometric analyses is not warranted due to the vast number of scanning and analysis parameters. However, our analysis suggests that researchers can optimize their individual processing procedures with respect to final segmentation quality and exemplifies adequate performance criteria.
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Effect of cognitive-behavioral therapy on neural correlates of fear conditioning in panic disorder.
Biol. Psychiatry
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Learning by conditioning is a key ability of animals and humans for acquiring novel behavior necessary for survival in a changing environment. Aberrant conditioning has been considered a crucial factor in the etiology and maintenance of panic disorder with agoraphobia (PD/A). Cognitive-behavioral therapy (CBT) is an effective treatment for PD/A. However, the neural mechanisms underlying the effects of CBT on conditioning processes in PD/A are unknown.
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Baseline activity predicts working memory load of preceding task condition.
Hum Brain Mapp
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The conceptual notion of the so-called resting state of the brain has been recently challenged by studies indicating a continuing effect of cognitive processes on subsequent rest. In particular, activity in posterior parietal and medial prefrontal areas has been found to be modulated by preceding experimental conditions. In this study, we investigated which brain areas show working memory dependent patterns in subsequent baseline periods and how specific they are for the preceding experimental condition. During functional magnetic resonance imaging, 94 subjects performed a letter-version of the n-back task with the conditions 0-back and 2-back followed by a low-level baseline in which subjects had to passively observe the letters appearing. In a univariate analysis, 2-back served as control condition while 0-back, baseline after 0-back and baseline after 2-back were modeled as regressors to test for activity changes between both baseline conditions. Additionally, we tested, using Gaussian process classifiers, the recognition of task condition from functional images acquired during baseline. Besides the expected activity changes in the precuneus and medial prefrontal cortex, we found differential activity in the thalamus, putamen, and postcentral gyrus that were affected by the preceding task. The multivariate analysis revealed that images of the subsequent baseline block contain task related patterns that yield a recognition rate of 70%. The results suggest that the influence of a cognitive task on subsequent baseline is strong and specific for some areas but not restricted to areas of the so-called default mode network.
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The influence of spatial registration on detection of cerebral asymmetries using voxel-based statistics of fractional anisotropy images and TBSS.
PLoS ONE
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The sensitivity of diffusion tensor imaging (DTI) for detecting microstructural white matter alterations has motivated the application of voxel-based statistics (VBS) to fractional anisotropy (FA) images (FA-VBS). However, detected group differences may depend on the spatial registration method used. The objective of this study was to investigate the influence of spatial registration on detecting cerebral asymmetries in FA-VBS analyses with reference to data obtained using Tract-Based Spatial Statistics (TBSS). In the first part of this study we performed FA-VBS analyses using three single-contrast and one multi-contrast registration: (i) whole-brain registration based on T2 contrast, (ii) whole-brain registration based on FA contrast, (iii) individual-hemisphere registration based on FA contrast, and (iv) a combination of (i) and (iii). We then compared the FA-VBS results with those obtained from TBSS. We found that the FA-VBS results depended strongly on the employed registration approach, with the best correspondence between FA-VBS and TBSS results when approach (iv), the "multi-contrast individual-hemisphere" method was employed. In the second part of the study, we investigated the spatial distribution of residual misregistration for each registration approach and the effect on FA-VBS results. For the FA-VBS analyses using the three single-contrast registration methods, we identified FA asymmetries that were (a) located in regions prone to misregistrations, (b) not detected by TBSS, and (c) specific to the applied registration approach. These asymmetries were considered candidates for apparent FA asymmetries due to systematic misregistrations associated with the FA-VBS approach. Finally, we demonstrated that the "multi-contrast individual-hemisphere" approach showed the least residual spatial misregistrations and thus might be most appropriate for cerebral FA-VBS analyses.
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High seroprevalence of Coxiella burnetii antibodies in veterinarians associated with cattle obstetrics, Bavaria, 2009.
Vector Borne Zoonotic Dis.
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Q fever is a zoonosis caused by Coxiella burnetii. Infection can result in severe disease. However, little is known about the risk of infection in veterinarians. In a cross-sectional study among German veterinarians, participants provided sera and completed an exposure questionnaire. We investigated predictors for seropositivity using multivariable logistic regression modelling. The 424 participants median age was 40 (18-74) years, and 276 (65%) were female. Sera of 162 (38%) were positive for Coxiella burnetii phase II IgG antibodies (by ELISA and IFAT). Predictors for seropositivity were occupational exposure to cattle (aOR 2.83, 95% CI 1.64-4.87), occupational exposure to sheep (2.09, 1.22-3.58), male sex (1.9, 1.15-3.13), and increasing age (30-39 years: 4.91, 2.00-12.04; 40-49 years: 5.32, 2.12-13.33; >50 years: 6.70, 2.60-17.25; compared with <30 years). When investigating occupational exposure to cattle and sheep in detail in a separate model, the seroprevalence increased with increasing numbers of cattle obstetrics procedures performed per month, and with increasing numbers of individual cattle treated per week. The high antibody prevalence implies a high lifetime-risk of Q fever in veterinarians. Cattle veterinarians, especially those frequently performing obstetrics, should be counseled early in their career on the clinical picture of Q fever, and on specific risks.
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Regional gray matter changes in obsessive-compulsive disorder: relationship to clinical characteristics.
Psychiatry Res
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Regional brain volumes were compared between 23 participants with obsessive-compulsive disorder (OCD) and 36 healthy controls using magnetic resonance imaging with voxel-based morphometry. A volumetric decrease in OCD was found in the right mediofrontal cortex. An increase was found in the left temporoparietal cortex. Volume alterations were related to symptom severity and age of onset.
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Sharing more than friendship--nasal colonization with coagulase-positive staphylococci (CPS) and co-habitation aspects of dogs and their owners.
PLoS ONE
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Since the relationship between dogs and their owners has changed, and dogs moved from being working dogs to family members in post-industrial countries, we hypothesized that zoonotic transmission of opportunistic pathogens like coagulase positive staphylococci (CPS) is likely between dogs and their owners.
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Determination of crossed language dominance: dissociation of language lateralization within the temporoparietal cortex.
Neurocase
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Crossed language dominance is a rare form of language lateralization, characterized by a dissociation of anterior and posterior language regions. We present the case of a healthy subject whose language lateralization pattern, as assessed by functional magnetic resonance imaging, is reliably characterized as crossed language dominance based on a word generation task, but typical left-lateralized when a semantic decision task is applied. A single language task is therefore not sufficient to characterize language lateralization, at least not for subjects with rare forms of language dominance. In the pre-surgical diagnostic of language lateralization, several language tasks tapping into different aspects of language functions should be applied.
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JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.