University of AmsterdamAmsterdam


University of AmsterdamAmsterdam

Time filter
Source Type

Levy E.I.,University of AmsterdamAmsterdam | Maratina S.S.,Eijkman Institute for Molecular BiologyJakarta | De Jong J.J.,University of AmsterdamAmsterdam | Asih P.B.S.,Eijkman Institute for Molecular BiologyJakarta | And 3 more authors.
Malaria Journal | Year: 2015

Background: Malaria in pregnancy poses a major public health problem in Indonesia with an estimated six million pregnancies at risk of Plasmodium falciparum or Plasmodium vivax malaria annually. In 2010, Indonesia introduced a screen and treat policy for the control of malaria in pregnancy at first antenatal visit using microscopy or rapid diagnostic tests (RDTs). A diagnostic study was conducted in Sumba, Indonesia to compare the performance of four different RDTs in predominately asymptomatic pregnant women under field condition. Methods: Women were screened for malaria at antenatal visits using field microscopy and four HRP-2/pLDH combination RDTs (Carestart™, First-Response®, Parascreen® and SD-Bioline®). The test results were compared with expert microscopy and nested PCR. End user experience of the RDTs in the field was assessed by questionnaire. Results: Overall 950 were recruited and 98.7 % were asymptomatic. The prevalence of malaria was 3.0-3.4 % by RDTs, and 3.6, 5.0 and 6.6 % by field microscopy, expert microscopy and PCR, respectively. The geometric-mean parasite density was low (P. falciparum = 418, P. vivax = 147 parasites/μL). Compared with PCR, the overall sensitivity of the RDTs and field microscopy to detect any species was 24.6-31.1 %; specificities were >98.4 %. Relative to PCR, First-Response® had the best diagnostic accuracy (any species): sensitivity = 31.1 %, specificity = 98.9 % and diagnostic odds ratio = 39.0 (DOR). The DOR values for Carestart™, Parascreen®, SD-Bioline®, and field microscopy were 23.4, 23.7, 23.5 and 29.2, respectively. The sensitivity of Pan-pLDH bands to detect PCR confirmed P. vivax mono-infection were 8.6-13.0 %. The sensitivity of the HRP-2 band alone to detect PCR confirmed P. falciparum was 10.3-17.9 %. Pan-pLDH detected P. falciparum cases undetected by the HRP-2 band resulting in a better test performance when both bands were combined. First Response® was preferred by end-users for the overall practicality. Conclusion: The diagnostic accuracy to detect malaria among mostly asymptomatic pregnant women and perceived ease of use was slightly better with First-Response®, but overall, differences between the four RDTs were small and performance comparable to field microscopy. Combination RDTs are a suitable alternative to field microscopy to screen for malaria in pregnancy in rural Indonesia. The clinical relevance of low density malaria infections detected by PCR, but undetected by RDTs or microscopy needs to be determined. © 2015 Ahmed et al.

Van Unen J.,University of AmsterdamAmsterdam | Woolard J.,University of Nottingham | Rinken A.,University of Tartu | Hoffmann C.,University of Würzburg | And 5 more authors.
Molecular Pharmacology | Year: 2015

The last frontier for a complete understanding of G-protein-coupled receptor (GPCR) biology is to be able to assess GPCR activity, interactions, and signaling in vivo, in real time within biologically intact systems. This includes the ability to detect GPCR activity, trafficking, dimerization, protein-protein interactions, second messenger production, and downstream signaling events with high spatial resolution and fast kinetic readouts. Resonance energy transfer (RET)-based biosensors allow for all of these possibilities in vitro and in cell-based assays, but moving RET into intact animals has proven difficult. Here, we provide perspectives on the optimization of biosensor design, of signal detection in living organisms, and the multidisciplinary development of in vitro and cell-based assays that more appropriately reflect the physiologic situation. In short, further development of RET-based probes, optical microscopy techniques, and mouse genome editing hold great potential over the next decade to bring real-time in vivo GPCR imaging to the forefront of pharmacology. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

PubMed | University of Amsterdam, University of AmsterdamAmsterdam and Electronic Microscopy Center Amsterdam
Type: | Journal: Frontiers in microbiology | Year: 2016

Spores are of high interest to the food and health sectors because of their extreme resistance to harsh conditions, especially against heat. Earlier research has shown that spores prepared on solid agar plates have a higher heat resistance than those prepared under a liquid medium condition. It has also been shown that the more mature a spore is, the higher is its heat resistance most likely mediated, at least in part, by the progressive cross-linking of coat proteins. The current study for the first time assesses, at the proteomic level, the effect of two commonly used sporulation conditions on spore protein presence.

Monk K.R.,University of Washington | Hamann J.,University of AmsterdamAmsterdam | Langenhan T.,University of Würzburg | Nijmeijer S.,VU University Amsterdam | And 2 more authors.
Molecular Pharmacology | Year: 2015

The adhesion family of G protein-coupled receptors (aGPCRs) comprises 33 members in humans. aGPCRs are characterized by their enormous size and complex modular structures. While the physiologic importance of many aGPCRs has been clearly demonstrated in recent years, the underlying molecular functions have only recently begun to be elucidated. In this minireview, we present an overview of our current knowledge on aGPCR activation and signal transduction with a focus on the latest findings regarding the interplay between ligand binding, mechanical force, and the tethered agonistic Stachel sequence, as well as implications on translational approaches that may derive from understanding aGPCR pharmacology. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Scheibel M.G.,University of Gottingen | Abbenseth J.,University of Gottingen | Kinauer M.,University of Gottingen | Heinemann F.W.,Friedrich - Alexander - University, Erlangen - Nuremberg | And 3 more authors.
Inorganic Chemistry | Year: 2015

The redox series [Irn(NHx)(PNP)] (n = II-IV, x = 3-0; PNP = N(CHCHPtBu2)2) was examined with respect to electron, proton, and hydrogen atom transfer steps. The experimental and computational results suggest that the IrIII imido species [Ir(NH)(PNP)] is not stable but undergoes disproportionation to the respective IrII amido and IrIV nitrido species. N-H bond strengths are estimated upon reaction with hydrogen atom transfer reagents to rationalize this observation and are used to discuss the reactivity of these compounds toward E-H bond activation. © 2015 American Chemical Society.

PubMed | University of AmsterdamAmsterdam, Yale University and Institut Universitaire de France
Type: | Journal: Frontiers in systems neuroscience | Year: 2016

Beta and gamma rhythms have been hypothesized to be involved in global and local coordination of neuronal activity, respectively. Here, we investigated how cells in rodent area S1BF are entrained by rhythmic fluctuations at various frequencies within the local area and in connected areas, and how this depends on behavioral state and cell type. We performed simultaneous extracellular field and unit recordings in four connected areas of the freely moving rat (S1BF, V1M, perirhinal cortex, CA1). S1BF spiking activity was strongly entrained by both beta and gamma S1BF oscillations, which were associated with deactivations and activations, respectively. We identified multiple classes of fast spiking and excitatory cells in S1BF, which showed prominent differences in rhythmic entrainment and in the extent to which phase locking was modulated by behavioral state. Using an additional dataset acquired by whole-cell recordings in head-fixed mice, these cell classes could be compared with identified phenotypes showing gamma rhythmicity in their membrane potential. We next examined how S1BF cells were entrained by rhythmic fluctuations in connected brain areas. Gamma-synchronization was detected in all four areas, however we did not detect significant gamma coherence among these areas. Instead, we only found long-range coherence in the theta-beta range among these areas. In contrast to local S1BF synchronization, we found long-range S1BF-spike to CA1-LFP synchronization to be homogeneous across inhibitory and excitatory cell types. These findings suggest distinct, cell-type contributions of low and high-frequency synchronization to intra- and inter-areal neuronal interactions.

Shahi S.,University of AmsterdamAmsterdam | Beerens B.,University of AmsterdamAmsterdam | Manders E.M.M.,University of AmsterdamAmsterdam | Rep M.,University of AmsterdamAmsterdam
Eukaryotic Cell | Year: 2015

Nuclear dynamics can vary widely between fungal species and between stages of development of fungal colonies. Here we compared nuclear dynamics and mitotic patterns between germlings and mature hyphae in Fusarium oxysporum. Using fluorescently labeled nuclei and live-cell imaging, we show that F. oxysporum is subject to a developmental transition from a uninucleate to a multinucleate state after completion of colony initiation. We observed a special type of hypha that exhibits a higher growth rate, possibly acting as a nutrient scout. The higher growth rate is associated with a higher nuclear count and mitotic waves involving 2 to 6 nuclei in the apical compartment. Further, we found that dormant nuclei of intercalary compartments can reenter the mitotic cycle, resulting in multinucleate compartments with up to 18 nuclei in a single compartment. © 2015, American Society for Microbiology. All Rights Reserved.

Moller E.L.,University of AmsterdamAmsterdam | Bogels S.M.,University of AmsterdamAmsterdam
International Journal of Methods in Psychiatric Research | Year: 2016

With DSM-5, the American Psychiatric Association encourages complementing categorical diagnoses with dimensional severity ratings. We therefore examined the psychometric properties of the DSM-5 Dimensional Anxiety Scales, a set of brief dimensional scales that are consistent in content and structure and assess DSM-5-based core features of anxiety disorders. Participants (285 males, 255 females) completed the DSM-5 Dimensional Anxiety Scales for social anxiety disorder, generalized anxiety disorder, specific phobia, agoraphobia, and panic disorder that were included in previous studies on the scales, and also for separation anxiety disorder, which is included in the DSM-5 chapter on anxiety disorders. Moreover, they completed the Screen for Child Anxiety Related Emotional Disorders Adult version (SCARED-A). The DSM-5 Dimensional Anxiety Scales demonstrated high internal consistency, and the scales correlated significantly and substantially with corresponding SCARED-A subscales, supporting convergent validity. Separation anxiety appeared present among adults, supporting the DSM-5 recognition of separation anxiety as an anxiety disorder across the life span. To conclude, the DSM-5 Dimensional Anxiety Scales are a valuable tool to screen for specific adult anxiety disorders, including separation anxiety. Research in more diverse and clinical samples with anxiety disorders is needed. © 2016 The Authors International Journal of Methods in Psychiatric Research Published by John Wiley & Sons Ltd. © 2016 The Authors International Journal of Methods in Psychiatric Research Published by John Wiley & Sons Ltd.

PubMed | University of Amsterdam and University of AmsterdamAmsterdam
Type: | Journal: Frontiers in human neuroscience | Year: 2016

A core symptom of anxiety disorders is the tendency to interpret ambiguous information as threatening. Using electroencephalography and blood oxygenation level dependent magnetic resonance imaging (BOLD-MRI), several studies have begun to elucidate brain processes involved in fear-related perceptual biases, but thus far mainly found evidence for general hypervigilance in high fearful individuals. Recently, multi-voxel pattern analysis (MVPA) has become popular for decoding cognitive states from distributed patterns of neural activation. Here, we used this technique to assess whether biased fear generalization, characteristic of clinical fear, is already present during the initial perception and categorization of a stimulus, or emerges during the subsequent interpretation of a stimulus. Individuals with low spider fear (n = 20) and high spider fear (n = 18) underwent functional MRI scanning while viewing series of schematic flowers morphing to spiders. In line with previous studies, individuals with high fear of spiders were behaviorally more likely to classify ambiguous morphs as spiders than individuals with low fear of spiders. Univariate analyses of BOLD-MRI data revealed stronger activation toward spider pictures in high fearful individuals compared to low fearful individuals in numerous areas. Yet, neither average activation, nor support vector machine classification (i.e., a form of MVPA) matched the behavioral results - i.e., a biased response toward ambiguous stimuli - in any of the regions of interest. This may point to limitations of the current design, and to challenges associated with classifying emotional and neutral stimuli in groups that differ in their judgment of emotionality. Improvements for future research are suggested.

PubMed | University of Amsterdam, University of AmsterdamAmsterdam and VU University Amsterdam
Type: | Journal: Frontiers in human neuroscience | Year: 2016

Stroke commonly results in cognitive impairments in working memory, attention, and executive function, which may be restored with appropriate training programs. Our aim was to systematically review the evidence for computer-based cognitive training of executive dysfunctions.Studies were included if they concerned adults who had suffered stroke or other types of acquired brain injury, if the intervention was computer training of executive functions, and if the outcome was related to executive functioning. We searched in MEDLINE, PsycINFO, Web of Science, and The Cochrane Library. Study quality was evaluated based on the CONSORT Statement. Treatment effect was evaluated based on differences compared to pre-treatment and/or to a control group.Twenty studies were included. Two were randomized controlled trials that used an active control group. The other studies included multiple baselines, a passive control group, or were uncontrolled. Improvements were observed in tasks similar to the training (near transfer) and in tasks dissimilar to the training (far transfer). However, these effects were not larger in trained than in active control groups. Two studies evaluated neural effects and found changes in both functional and structural connectivity. Most studies suffered from methodological limitations (e.g., lack of an active control group and no adjustment for multiple testing) hampering differentiation of training effects from spontaneous recovery, retest effects, and placebo effects.The positive findings of most studies, including neural changes, warrant continuation of research in this field, but only if its methodological limitations are addressed.

Loading University of AmsterdamAmsterdam collaborators
Loading University of AmsterdamAmsterdam collaborators