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Search Results: 1 - 10 of 47781 matches for " Christian van Weeghel "
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Lysozyme Resistance in Streptococcus suis Is Highly Variable and Multifactorial
Paul J. Wichgers Schreur, Christian van Weeghel, Johanna M. J. Rebel, Mari A. Smits, Jos P. M. van Putten, Hilde E. Smith
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0036281
Abstract: Background Streptococcus suis is an important infectious agent for pigs and occasionally for humans. The host innate immune system plays a key role in preventing and eliminating S. suis infections. One important constituent of the innate immune system is the protein lysozyme, which is present in a variety of body fluids and immune cells. Lysozyme acts as a peptidoglycan degrading enzyme causing bacterial lysis. Several pathogens have developed mechanisms to evade lysozyme-mediated killing. In the present study we compared the lysozyme sensitivity of various S. suis isolates and investigated the molecular basis of lysozyme resistance for this pathogen. Results The lysozyme minimal inhibitory concentrations of a wide panel of S. suis isolates varied between 0.3 to 10 mg/ml. By inactivating the oatA gene in a serotype 2 and a serotype 9 strain, we showed that OatA-mediated peptidoglycan modification partly contributes to lysozyme resistance. Furthermore, inactivation of the murMN operon provided evidence that additional peptidoglycan crosslinking is not involved in lysozyme resistance in S. suis. Besides a targeted approach, we also used an unbiased approach for identifying factors involved in lysozyme resistance. Based on whole genome comparisons of a lysozyme sensitive strain and selected lysozyme resistant derivatives, we detected several single nucleotide polymorphisms (SNPs) that were correlated with the lysozyme resistance trait. Two SNPs caused defects in protein expression of an autolysin and a capsule sugar transferase. Analysis of specific isogenic mutants, confirmed the involvement of autolysin activity and capsule structures in lysozyme resistance of S. suis. Conclusions This study shows that lysozyme resistance levels are highly variable among S. suis isolates and serotypes. Furthermore, the results show that lysozyme resistance in S. suis can involve different mechanisms including OatA-mediated peptidolycan modification, autolysin activity and capsule production.
Perfilando la investigación en rehabilitación psiquiátrica: Percepciones de los investigadores ("stakeholders")
Weeghel,Jaap van; Kroon,Hans;
The European journal of psychiatry (edición en espa?ol) , 2004, DOI: 10.4321/S1579-699X2004000200002
Abstract: la investigación en rehabilitación de personas con enfermedades mentales graves ha captado una gran atención en los últimos a?os, pero adolece de un perfil claro. varios expertos en rehabilitación de europa occidental participaron en un proceso de elaboración de un mapa conceptual para explorar los aspectos críticos de la investigación en rehabilitación psiquiátrica. los participantes se centraron en la investigación en rehabilitación y sus implicaciones prácticas. los aspectos metodológicos fueron de importancia secundaria. en base a ello, surge un perfil de investigación en rehabilitación psiquiátrica: está basado en la investigación aplicada guiada por un objetivo de "emancipación", y que produce conocimientos de uso inmediato para los pacientes y para la práctica (local).
Perfilando la investigación en rehabilitación psiquiátrica: Percepciones de los investigadores ("stakeholders")
Jaap van Weeghel,Hans Kroon
The European journal of psychiatry (edición en espa?ol) , 2004,
Abstract: La investigación en rehabilitación de personas con enfermedades mentales graves ha captado una gran atención en los últimos a os, pero adolece de un perfil claro. Varios expertos en rehabilitación de Europa occidental participaron en un proceso de elaboración de un mapa conceptual para explorar los aspectos críticos de la investigación en rehabilitación psiquiátrica. Los participantes se centraron en la investigación en rehabilitación y sus implicaciones prácticas. Los aspectos metodológicos fueron de importancia secundaria. En base a ello, surge un perfil de investigación en rehabilitación psiquiátrica: está basado en la investigación aplicada guiada por un objetivo de "emancipación", y que produce conocimientos de uso inmediato para los pacientes y para la práctica (local).
Note on mirror symmetry and coisotropic D-branes on tori
Christian van Enckevort
Mathematics , 2001,
Abstract: We describe mirror symmetry on higher dimensional tori, paying special attention to the behaviour of D-branes under mirror symmetry. To find the mirror D-branes the description of mirror symmetry on D-branes due to Ooguri, Oz en Yin is used. This method allows us to deal with the coisotropic D-branes recently introduced by Kapustin and Orlov. We compare this to the description of mirror symmetry on D-branes using the Fourier-Mukai transform of charges.
Moduli spaces and D-brane categories of tori using SCFT
Christian van Enckevort
Mathematics , 2003,
Abstract: We analyse the moduli spaces of superconformal field theories (SCFTs). For N=2 we find an enhanced moduli space which in geometrical terms corresponds to tori with two independent complex structures. To explain the precise relation with the moduli space of SCFTs on K3 surfaces as described by Aspinwall and Morrison, we discuss some subtleties with the precise interpretation of the N=2 and N=4 moduli spaces. We also explain why in some cases the SYZ-description of mirror symmetry as fibrewise T-duality seems to break down. Using gluing matrices we give an algebraic description of D-branes and construct the corresponding boundary states. We study how isomorphisms of the SCFTs act on D-branes. Finally we give a geometrical interpretation of our algebraic constructions and make contact with the geometrical D-brane categories and Kontsevich's homological mirror symmetry conjecture.
Criminal Victimisation in People with Severe Mental Illness: A Multi-Site Prevalence and Incidence Survey in the Netherlands
Astrid M. Kamperman, Jens Henrichs, Stefan Bogaerts, Emmanuel M. E. H. Lesaffre, André I. Wierdsma, Razia R. R. Ghauharali, Wilma Swildens, Yolanda Nijssen, Mark van der Gaag, Jan R. Theunissen, Philippe A. Delespaul, Jaap van Weeghel, Jooske T. van Busschbach, Hans Kroon, Linda A. Teplin, Dike van de Mheen, Cornelis L. Mulder
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0091029
Abstract: Background Although crime victimisation is as prevalent in psychiatric patients as crime perpetration (and possibly more so), few European figures for it are available. We therefore assessed its one-year prevalence and incident rates in Dutch severely mentally ill outpatients, and compared the results with victimisation rates in the general population. Method This multisite epidemiological survey included a random sample of 956 adult severely mentally ill outpatients. Data on victimisation were obtained using the victimisation scale of the Dutch Crime and Victimisation Survey, which assesses crime victimisation over the preceding 12 months. Comparison data were derived from the nationwide survey on safety and victimisation in the Netherlands. Prevalence and incident rates were weighted for sex, age, ethnicity and socioeconomic status, and compared with a general population sample matched by region (N = 38,227). Results In the past year, almost half of the severely mentally ill outpatients (47%) had been victim of a crime. After control for demographic differences, prevalence rates of overall and specific victimisation measures were significantly higher in severely mentally ill outpatients than in the general population. The relative rates were especially high for personal crimes such as violent threats (RR = 2.12, 95% CI: 1.72–2.61), physical assaults (RR = 4.85, 95% CI: 3.69–6.39) and sexual harassment and assaults (RR = 3.94, 95% CI: 3.05–5.09). In concordance, severely mentally ill outpatients reported almost 14 times more personal crime incidents than persons from the general population (IRR = 13.68, 95% CI: 12.85–14.56). Conclusion Crime victimisation is a serious problem in Dutch severely mentally ill outpatients. Mental-healthcare institutions and clinicians should become aware of their patients’ victimisation risk, and should implement structural measures to detect and prevent (re-)victimisation.
Monodromy calculatons of fourth order equations of Calabi-Yau type
Christian van Enckevort,Duco van Straten
Mathematics , 2004,
Abstract: This paper contains a preliminary study of the monodromy of certain fourth order differential equations, that were called of Calabi-Yau type in math.NT/0402386. Some of these equations can be interpreted as the Picard-Fuchs equations of a Calabi-Yau manifold with one complex modulus, which links up the observed integrality to the conjectured integrality of the Gopakumar-Vafa invariants. A natural question is if in the other cases such a geometrical interpretation is also possible. Our investigations of the monodromies are intended as a first step in answering this question. We use a numerical approach combined with some ideas from homological mirror symmetry to determine the monodromy for some further one-parameter models. Furthermore, we present a conjectural identification of the Picard-Fuchs equation for 5 new examples from Borcea's list and one constructed by Tonoli and conjecture the existence of some new Calabi-Yau three folds. The paper does not contain any theorems or proofs but is, we think, nevertheless of interest.
Rigid and Complete Intersection Lagrangian Singularities
Christian Sevenheck,Duco van Straten
Mathematics , 2003,
Abstract: In this article we prove a rigidity theorem for lagrangian singularities by studying the local cohomology of the lagrangian de Rham complex that was introduced in math.AG/0002083. The result can be applied to show the rigidity of all open swallowtails of dimension greater or equal than two. In the case of lagrangian complete intersection singularities the lagrangian de Rham complex turns out to be perverse. We also show that lagrangian complete intersection in dimension greater than two cannot be regular in codimension one.
Deformation of singular lagrangian subvarieties
Duco van Straten,Christian Sevenheck
Mathematics , 2000,
Abstract: We investigate deformations of lagrangian manifolds with singularities. We introduce a complex similar to the de Rham-complex whose cohomology calculates deformation spaces. Examples of singular lagrangian varieties are presented and deformations are calculated explicitly.
Anaesthesia generates neuronal insulin resistance by inducing hypothermia
Christian Holscher, Lidy van Aalten, Calum Sutherland
BMC Neuroscience , 2008, DOI: 10.1186/1471-2202-9-100
Abstract: We find that urethane- and ketamine-induced anaesthesia results in rapid activation of the phosphatidylinositol (PI) 3-kinase-protein kinase B (PKB) signalling pathway in the brain, increases tau phosphorylation while at the same time reducing basal activity of the Ras-ERK pathway. Subsequent injection of insulin does not alter the activity of either the PI 3-kinase or ERK signalling pathways, indicating a degree of neuronal molecular insulin resistance. However, if body temperature is maintained during anaesthesia then there is no alteration in the basal activity of these signalling molecules. Subsequent response of both pathways to insulin injection is restored.The data is consistent with a hypothermia related alteration in neuronal signalling following anaesthesia, and emphasises the importance of maintaining the body temperature of rodents when monitoring insulin (or growth factor/neurotrophic agent) action in the brain of anesthetised rodents.Insulin is produced by pancreatic β-cells, in response to rising plasma glucose levels, and initiates multiple metabolic changes to restore glucose homeostasis. A specific membrane glycoprotein acts as a high affinity sensor for insulin (insulin receptor (IR)) in many tissues (primarily liver, fat, muscle). The IR is expressed in many regions of the brain, including the hypothalamus, cortex, and hippocampus. Neuron specific deletion of the IR makes the animal more sensitive to diet induced obesity [1], implicating neuronal IR in the satiety response. Consistent with this, administration of insulin to the arcuate nucleus in the hypothalamus has significant effects on feeding and body weight [2-4].Epidemiological evidence suggests that whole body insulin resistance, related to obesity, increases the risk of Alzheimer's disease, as well as vascular dementia [5-7]. In addition, there are molecular links between the development of Type 2 diabetes (an insulin resistant state) and Alzheimers's disease [8]. For example, GSK3β acti
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