Daniel Janssen - Academia.edu (original) (raw)

Papers by Daniel Janssen

Research paper thumbnail of Invest in What Energizes Students to Learn: Investigating Students’ Attitude towards Debate in the Foreign Language Classroom

Journal of Language Teaching and Research, 2015

Research paper thumbnail of Integrating research into business and corporate communication degree programs: case: master's program in multilingual professional communication at the University of Antwerp

Research paper thumbnail of Experimental strategies for frost analysis

Research paper thumbnail of Schreiberwerb in der Primarstufe mit Hilfe des differenziellen Lernansatzes *

Der Erwerb der Handschrift kann als Meilenstein in der Entwicklung zum sozial interaktiven Wesen ... more Der Erwerb der Handschrift kann als Meilenstein in der Entwicklung zum sozial interaktiven Wesen gesehen werden.

Research paper thumbnail of Validation of reference genes for quantitative real-time PCR studies in the dentate gyrus after experimental febrile seizures

Bmc Research Notes, Dec 13, 2012

Background: Quantitative real-time PCR (qPCR) is a commonly used technique to quantify gene expre... more Background: Quantitative real-time PCR (qPCR) is a commonly used technique to quantify gene expression levels. Validated normalization is essential to obtain reliable qPCR data. In that context, normalizing to multiple reference genes has become the most popular method. However, expression of reference genes may vary per tissue type, developmental stage and in response to experimental treatment. It is therefore imperative to determine stable reference genes for a specific sample set and experimental model. The present study was designed to validate potential reference genes in hippocampal tissue from rats that had experienced early-life febrile seizures (FS). To this end, we applied an established model in which FS were evoked by exposing 10-day old rat pups to heated air. One week later, we determined the expression stability of seven frequently used reference genes in the hippocampal dentate gyrus. Results: Gene expression stability of 18S rRNA, ActB, GusB, Arbp, Tbp, CycA and Rpl13A was tested using geNorm and Normfinder software. The ranking order of reference genes proposed by geNorm was not identical to that suggested by Normfinder. However, both algorithms indicated CycA, Rpl13A and Tbp as the most stable genes, whereas 18S rRNA and ActB were found to be the least stably expressed genes.

Research paper thumbnail of Dorsal Unpaired Median Neurons of Locusta migratoria Express Ivermectin- and Fipronil-Sensitive Glutamate-Gated Chloride Channels

Journal of Neurophysiology, Apr 1, 2007

Kerkhove E. Dorsal unpaired median neurons of Locusta migratoria express ivermectin-and fipronil-... more Kerkhove E. Dorsal unpaired median neurons of Locusta migratoria express ivermectin-and fipronil-sensitive glutamate-gated chloride channels. . Together with type A GABA and strychnine-sensitive glycine receptors, glutamate-gated chloride channels (GluCl) are members of the Cys-loop family of ionotropic receptors, which mediate fast inhibitory neurotransmission. To date, GluCls are found in invertebrates only and therefore represent potential specific targets for insecticides, such as ivermectin and fipronil. In this study, we identified the functional expression of GluCls in dorsal unpaired median (DUM) neurons of the metathoracic ganglion of Locusta migratoria using electrophysiological and molecular biological techniques. In whole cell patch-clamped DUM neurons, glutamate-induced changes in both their membrane potentials (current-clamp) and currents (voltage-clamp) were dependent on the chloride equilibrium potential. On continuous application of glutamate, the glutamate-elicited current response became rapidly and completely desensitized. Application of glutamate in the presence of 10 M fipronil or 100 M picrotoxin reversibly decreased GluClmediated currents by 87 and 39%, respectively. Furthermore, 1 M ivermectin induced a persistent chloride current, suggesting the expression of ivermectin-sensitive GluCl ␣ subunits. A degenerate PCR/RACE strategy was used to clone the full-length L. migratoria LmGlCl␣ subunit. Finally, RT-PCR experiments demonstrated the presence of LmGluCl␣ transcripts in locust DUM neurons. Our results provide the first direct evidence of a functional ivermectin-sensitive GluCl channel on the cell surface of DUM neurons of L. migratoria. Cully DF, Paress PS, Liu KK, Schaeffer JM, Arena JP. Identification of a Drosophila melanogaster glutamate-gated chloride channel sensitive to the antiparasitic agent avermectin. Cully DF, Vassilatis DK, Liu KK, Paress PS, Van der Ploeg LH, Schaeffer JM, Arena JP. Cloning of an avermectin-sensitive glutamate-gated chloride channel from Caenorhabditis elegans. Nature 371: 707-711, 1994. Dent JA, Smith MM, Vassilatis DK, Avery L. The genetics of ivermectin resistance in Caenorhabditis elegans. Proc Natl Acad Sci USA 97: 2674 -2679, 2000. Dent JA, Wayne DM, Avery L. avr-15 encodes a chloride channel subunit that mediates inhibitory glutamergic neurotransmission and ivermectin sensitivity in Caenorhabditis elegans. EMBO J 16: 5867-5879, 1997. Dubas F. Actions of the putative amino acid neurotransmitter on the neuropile arborization of locust flight motoneurones. J. Exp Biol 155: 337-356, 1991. Dudel J, Franke C. Single glutamate-gated synaptic channels at the crayfish neuromuscular junction. II. Dependence of channel open time on glutamate concentration. Pfluegers Arch 408: 307-314, 1987. Dudel J, Franke C, Hatt H, Usherwood PN. Chloride channels gated by extrajunctional glutamate receptors (H-receptors) on locust leg muscle. Brain Res 481: 215-220, 1989. Forrester SG, Prichard RK, Dent JA, Beech R. Haemonchus contortus: HcGluCla expressed in Xenopus oocytes forms a glutamate-gated channel that is activated by ibotenate and the antiparasitic drug ivermectin. Mol Biochem Parasitol 192: 115-121, 2003. Grolleau F, Lapied B. Dorsal unpaired median neurones in the insect central nervous system: towards a better understanding of the ionic mechanisms underlying spontaneous electrical activity. J Exp Biol 203: 1633-1648, 2000. Heckmann M, Dudel J. Recordings of glutamate-gated ion channels in outside-out patches from Drosophila larval muscle. Neurosci Lett 196: 53-56, 1995. Heidel E, Pfluger HJ. Ion currents and spiking properties of identified subtypes of locust octopaminergic dorsal unpaired median neurons. Eur J Neurosci 23: 1189 -1206, 2006. Hogner A, Kastrup JS, Jin R, Liljefors T, Mayer ML, Egebjerg J, Larsen IK, Gouaux E. Structural basis for AMPA receptor activation and ligand selectivity: crystal structures of five agonist complexes with the GluR2 ligand-binding core. J Mol Biol 322: 93-109, 2002. Horoszok L, Raymond V, Satelle DB, Wostenholme AJ. GLC-3: a novel fipronil and BIDN-sensitive, but picrotoxinin-insensitive, L-glutamate-gate chloride channel subunit from Caenorhabditis elegans. Br J Pharmacol 132: 1247-1254, 2001. Ikeda T, Zhao X, Kono Y, Yeh JZ, Narahashi T. Fipronil modulation of glutamate-induced chloride currents in cockroach thoracic ganglion neurons. Neurotoxicology 24: 807-815, 2003. Jones AK, Sattelle DB. The cys-loop ligand-gated ion channel superfamily of the honeybee, Apis mellifera. Invert Neurosci 6: 123-132, 2006.

Research paper thumbnail of In vivo imaging of NF-?B activity during Escherichia coli-induced mammary gland infection

Research paper thumbnail of Morphological changes do not reflect biochemical and functional differentiation in OLN-93 oligodendroglial cells

Journal of Neuroscience Methods, Aug 1, 2009

a b s t r a c t OLN-93 cells, a cell line established from spontaneously transformed rat brain gl... more a b s t r a c t OLN-93 cells, a cell line established from spontaneously transformed rat brain glial cultures, are used as a model for oligodendrocytes. These cells are known to undergo morphological changes upon serum deprivation. The objective of the present study is to investigate a possible correlation between these morphological changes and (1) the loss or gain of oligodendrocyte markers and (2) the electrophysiological properties of these cells. Using RT-PCR and immunocytochemistry, we demonstrate that the OLN-93 cell line expresses a broad range of markers (NG2, CNP, MAG, MOG) both when cultured in medium containing 10% or 0.5% fetal calf serum. Whole-cell patch-clamp recordings demonstrate that, regardless of the culture conditions, OLN-93 cells mainly express delayed-rectifying K + currents, a characteristic of immature oligodendrocytes. These currents are in part mediated by the shaker family of voltage-gated potassium channels. Kv1.1 and Kv1.3-expression are present at the mRNA and at the protein levels, and functional evidence for Kv1.3 mediated currents was obtained by using the selective blocker margatoxin. Under low serum conditions, OLN-93 cells exhibit differentiation-like morphological changes. However, we provide evidence that these morphological modifications do not necessarily correlate with biochemical or functional changes. Based on these data, we conclude that the OLN-93 cell line can be situated at a developmental stage between a late pre-oligodendrocyte and a late immature oligodendrocyte, regardless of serum concentration.

Research paper thumbnail of Atomic frequency standard based upon coherent population trapping

Research paper thumbnail of Optically pumped atomic frequency standard

Research paper thumbnail of Resistance of Concrete to Freezing and Thawing

key words: aggregate D-cracking durability factor freezing and thawing modal analysis portland ce... more key words: aggregate D-cracking durability factor freezing and thawing modal analysis portland cement concrete quality factor resonance frequency Strategic Highway Research Program

Research paper thumbnail of Recognition of jumping patterns in volleyball after traditional and differential strength training by means of artificial neural nets

Research paper thumbnail of Handwriting acquisition in primary school by means of the differential learning approach *

The acquisition of handwriting is one of the mile-stones within the development of humans for be-... more The acquisition of handwriting is one of the mile-stones within the development of humans for be-coming social interactive beings. As handwriting is a movement skill, analogies to traditional ap-proaches in teaching sports skills are observable. Traditionally, children are taught to form letters with the correct sequence of strokes from the be-ginning. Thereby instructions include detailed pre-scriptions for pen, pen hold, hand movement and body position. In contrast, the differential learn-ing approach suggests stochastic perturbations and information on the difference of two subsequent movements as basis for learning. The aim of the present study is to transfer the differential learn-ing approach on handwriting acquisition in primary school. Two groups of 11 first-graders (6.8 ± 0.63 years) participated in a pre-posttest design with reten-tion and transfer test. The test included 23 tasks on symbol, pattern, character, word, and sentence level and was executed on a digitizing tabl...

Research paper thumbnail of Stochastic perturbations in athletic field events enhance skill acquisition

Research paper thumbnail of Dynamics and organization of alpha3-containing glycine receptors using single molecule detection

The Glycine receptor (GlyR) is a chloride permeable ligand gated ion channel and that can mediate... more The Glycine receptor (GlyR) is a chloride permeable ligand gated ion channel and that can mediate synaptic inhibition. Due to a possible involvement in the pathophysiology of temporal lobe epilepsy,the different properties of GlyRs containing alpha3L and K subunit isoforms are currently investigated. Previous characterizaions of homomeric receptors consisting of these isoforms have shown a difference in their electrophysiological properties and their membrane distribution as observed by diffraction-limited fluorescence microscopy. We studied these isoforms, when separately expressed in tranfected HEK 293T cells, by using single molecule tracking (SMT) in living cells and direct stochastic optical reconstruction microscopy (dSTORM) on fixated cells. For both techniquest the GlyRs are stained using a primary antibody directly labeled with Alexa Fluor dyes. The dSTORM experiments support the observation that the alpha3L GlyR are clustered, while the alpha3K GlyRs are more uniformly spr...

Research paper thumbnail of Coherent Population Trapping and Intensity Optical Pumping: On Their Use in Atomic Frequency Standards

Frequency Standards and Metrology - Proceedings of the 6th Symposium, 2002

The paper summarizes the relative advantages and disadvantages of Coherent Population Trapping (C... more The paper summarizes the relative advantages and disadvantages of Coherent Population Trapping (CPT) and Intensity Optical Pumping (IOP) for the implementation of a passive atomic frequency standard. The paper outlines the basic principles common to both CPT and IOP when ...

Research paper thumbnail of Increase in Escherichia coli inoculum dose accelerates CD8+ T-cell trafficking in the primiparous bovine mammary gland

Journal of dairy science, 2008

Although migration of leukocytes into the mammary gland is pivotal for a cow's response again... more Although migration of leukocytes into the mammary gland is pivotal for a cow's response against intramammary invading pathogens, the contribution of lymphocyte subsets to this response remains unclear. To investigate the dynamics of lymphocyte populations during Escherichia coli mastitis, T-lymphocyte subsets, CD4+/CD8+ ratio, CD21+ cells, and lymphoproliferation were studied in blood and milk of primiparous cows exposed to different quantities of bacteria. The cows were intramammarily inoculated with 10(4) cfu of E. coli (group A) and 10(6) cfu (group B). Compared with group A, a much greater number of lymphocytes migrated into the infected quarters at postinfection hour (PIH) 6 to 24 in group B, and the CD8+ cells were the first-recruited T cells in the milk. There was a significant decline in the CD4+/CD8+ ratios at PIH 6 to 24 in group B. The decrease of CD4+/CD8+ ratios at PIH 6 to 24 resulted mainly from greater CD8+ cell concentrations in milk. In contrast, at PIH 72, CD4...

Research paper thumbnail of The coherent population trapping passive frequency standard

Conference on Precision Electromagnetic Measurements, 2002

Coherent population trapping in alkali atoms has opened a new avenue in the implementation of ato... more Coherent population trapping in alkali atoms has opened a new avenue in the implementation of atomic frequency standards having promising characteristics for field use. The paper reviews the state of the art in this subject and describes recent results obtained in the case of a passive Rb standard implemented using such an approach.

Research paper thumbnail of Glycine enhances microglial intracellular calcium signaling. A role for sodium-coupled neutral amino acid transporters

Pflügers Archiv - European Journal of Physiology, 2011

The inhibitory neurotransmitter glycine is known to enhance microglial nitric oxide production. H... more The inhibitory neurotransmitter glycine is known to enhance microglial nitric oxide production. However, up to now, the mechanism is undocumented. Since calcium is an important second messenger in both immune and glial cells, we studied the effects of glycine on intracellular calcium signaling. We found that millimolar concentrations of glycine enhance microglial intracellular calcium transients induced by 100 μM ATP or by 500 nM thapsigargin. This modulation was unaffected by the glycine receptor antagonist strychnine and could not be mimicked by glycine receptor agonists such as taurine or β-alanine, indicating glycine receptor independency. The modulation of calcium responses could be mimicked by several structurally related amino acids (e.g., serine, alanine, or glutamine) and was inhibited in the presence of the neutral amino acid transporter substrate α-aminoisobutyric acid (AIB). We correlated these findings to immunofluorescence glycine uptake experiments which showed a clear glycine uptake which was inhibited by AIB. Furthermore, all amino acids that were shown to modulate calcium responses also evoked AIB-sensitive inward currents, mainly carried by sodium, as demonstrated by patch clamp experiments. Based on these findings, we propose that sodium-coupled neutral amino acid transporters are responsible for the observed glycine modulation of intracellular calcium responses.

Research paper thumbnail of Cell proliferation monitoring by multiplexed electrochemical impedance spectroscopy on microwell assays

Physica Status Solidi C: Current Topics in Solid State Physics, Vol 10, No 5, 2013

ABSTRACT Cell proliferation can be monitored by a wide range of well-established techniques. Most... more ABSTRACT Cell proliferation can be monitored by a wide range of well-established techniques. Most of the principles used rely on optical, single end-point methods, often involving the use of absorbent, fluorescent or luminescent compounds. These additives can interfere with the cell growth, thus producing distorted results. Electrochemical impedance spectroscopy provides a solution for this problem and enables continuous monitoring without interference. However equipment for this measurement technique is often bulky, highly expensive and lacks multichannel features. This paper presents a low-cost, compact hardware platform optimized for proliferation measurements, together with custom software to ease interpretation and physical modelling of data. Performance is demonstrated and measurement parameters are fine-tuned for three commonly used cell types in proliferation measurements. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Research paper thumbnail of Invest in What Energizes Students to Learn: Investigating Students’ Attitude towards Debate in the Foreign Language Classroom

Journal of Language Teaching and Research, 2015

Research paper thumbnail of Integrating research into business and corporate communication degree programs: case: master's program in multilingual professional communication at the University of Antwerp

Research paper thumbnail of Experimental strategies for frost analysis

Research paper thumbnail of Schreiberwerb in der Primarstufe mit Hilfe des differenziellen Lernansatzes *

Der Erwerb der Handschrift kann als Meilenstein in der Entwicklung zum sozial interaktiven Wesen ... more Der Erwerb der Handschrift kann als Meilenstein in der Entwicklung zum sozial interaktiven Wesen gesehen werden.

Research paper thumbnail of Validation of reference genes for quantitative real-time PCR studies in the dentate gyrus after experimental febrile seizures

Bmc Research Notes, Dec 13, 2012

Background: Quantitative real-time PCR (qPCR) is a commonly used technique to quantify gene expre... more Background: Quantitative real-time PCR (qPCR) is a commonly used technique to quantify gene expression levels. Validated normalization is essential to obtain reliable qPCR data. In that context, normalizing to multiple reference genes has become the most popular method. However, expression of reference genes may vary per tissue type, developmental stage and in response to experimental treatment. It is therefore imperative to determine stable reference genes for a specific sample set and experimental model. The present study was designed to validate potential reference genes in hippocampal tissue from rats that had experienced early-life febrile seizures (FS). To this end, we applied an established model in which FS were evoked by exposing 10-day old rat pups to heated air. One week later, we determined the expression stability of seven frequently used reference genes in the hippocampal dentate gyrus. Results: Gene expression stability of 18S rRNA, ActB, GusB, Arbp, Tbp, CycA and Rpl13A was tested using geNorm and Normfinder software. The ranking order of reference genes proposed by geNorm was not identical to that suggested by Normfinder. However, both algorithms indicated CycA, Rpl13A and Tbp as the most stable genes, whereas 18S rRNA and ActB were found to be the least stably expressed genes.

Research paper thumbnail of Dorsal Unpaired Median Neurons of Locusta migratoria Express Ivermectin- and Fipronil-Sensitive Glutamate-Gated Chloride Channels

Journal of Neurophysiology, Apr 1, 2007

Kerkhove E. Dorsal unpaired median neurons of Locusta migratoria express ivermectin-and fipronil-... more Kerkhove E. Dorsal unpaired median neurons of Locusta migratoria express ivermectin-and fipronil-sensitive glutamate-gated chloride channels. . Together with type A GABA and strychnine-sensitive glycine receptors, glutamate-gated chloride channels (GluCl) are members of the Cys-loop family of ionotropic receptors, which mediate fast inhibitory neurotransmission. To date, GluCls are found in invertebrates only and therefore represent potential specific targets for insecticides, such as ivermectin and fipronil. In this study, we identified the functional expression of GluCls in dorsal unpaired median (DUM) neurons of the metathoracic ganglion of Locusta migratoria using electrophysiological and molecular biological techniques. In whole cell patch-clamped DUM neurons, glutamate-induced changes in both their membrane potentials (current-clamp) and currents (voltage-clamp) were dependent on the chloride equilibrium potential. On continuous application of glutamate, the glutamate-elicited current response became rapidly and completely desensitized. Application of glutamate in the presence of 10 M fipronil or 100 M picrotoxin reversibly decreased GluClmediated currents by 87 and 39%, respectively. Furthermore, 1 M ivermectin induced a persistent chloride current, suggesting the expression of ivermectin-sensitive GluCl ␣ subunits. A degenerate PCR/RACE strategy was used to clone the full-length L. migratoria LmGlCl␣ subunit. Finally, RT-PCR experiments demonstrated the presence of LmGluCl␣ transcripts in locust DUM neurons. Our results provide the first direct evidence of a functional ivermectin-sensitive GluCl channel on the cell surface of DUM neurons of L. migratoria. Cully DF, Paress PS, Liu KK, Schaeffer JM, Arena JP. Identification of a Drosophila melanogaster glutamate-gated chloride channel sensitive to the antiparasitic agent avermectin. Cully DF, Vassilatis DK, Liu KK, Paress PS, Van der Ploeg LH, Schaeffer JM, Arena JP. Cloning of an avermectin-sensitive glutamate-gated chloride channel from Caenorhabditis elegans. Nature 371: 707-711, 1994. Dent JA, Smith MM, Vassilatis DK, Avery L. The genetics of ivermectin resistance in Caenorhabditis elegans. Proc Natl Acad Sci USA 97: 2674 -2679, 2000. Dent JA, Wayne DM, Avery L. avr-15 encodes a chloride channel subunit that mediates inhibitory glutamergic neurotransmission and ivermectin sensitivity in Caenorhabditis elegans. EMBO J 16: 5867-5879, 1997. Dubas F. Actions of the putative amino acid neurotransmitter on the neuropile arborization of locust flight motoneurones. J. Exp Biol 155: 337-356, 1991. Dudel J, Franke C. Single glutamate-gated synaptic channels at the crayfish neuromuscular junction. II. Dependence of channel open time on glutamate concentration. Pfluegers Arch 408: 307-314, 1987. Dudel J, Franke C, Hatt H, Usherwood PN. Chloride channels gated by extrajunctional glutamate receptors (H-receptors) on locust leg muscle. Brain Res 481: 215-220, 1989. Forrester SG, Prichard RK, Dent JA, Beech R. Haemonchus contortus: HcGluCla expressed in Xenopus oocytes forms a glutamate-gated channel that is activated by ibotenate and the antiparasitic drug ivermectin. Mol Biochem Parasitol 192: 115-121, 2003. Grolleau F, Lapied B. Dorsal unpaired median neurones in the insect central nervous system: towards a better understanding of the ionic mechanisms underlying spontaneous electrical activity. J Exp Biol 203: 1633-1648, 2000. Heckmann M, Dudel J. Recordings of glutamate-gated ion channels in outside-out patches from Drosophila larval muscle. Neurosci Lett 196: 53-56, 1995. Heidel E, Pfluger HJ. Ion currents and spiking properties of identified subtypes of locust octopaminergic dorsal unpaired median neurons. Eur J Neurosci 23: 1189 -1206, 2006. Hogner A, Kastrup JS, Jin R, Liljefors T, Mayer ML, Egebjerg J, Larsen IK, Gouaux E. Structural basis for AMPA receptor activation and ligand selectivity: crystal structures of five agonist complexes with the GluR2 ligand-binding core. J Mol Biol 322: 93-109, 2002. Horoszok L, Raymond V, Satelle DB, Wostenholme AJ. GLC-3: a novel fipronil and BIDN-sensitive, but picrotoxinin-insensitive, L-glutamate-gate chloride channel subunit from Caenorhabditis elegans. Br J Pharmacol 132: 1247-1254, 2001. Ikeda T, Zhao X, Kono Y, Yeh JZ, Narahashi T. Fipronil modulation of glutamate-induced chloride currents in cockroach thoracic ganglion neurons. Neurotoxicology 24: 807-815, 2003. Jones AK, Sattelle DB. The cys-loop ligand-gated ion channel superfamily of the honeybee, Apis mellifera. Invert Neurosci 6: 123-132, 2006.

Research paper thumbnail of In vivo imaging of NF-?B activity during Escherichia coli-induced mammary gland infection

Research paper thumbnail of Morphological changes do not reflect biochemical and functional differentiation in OLN-93 oligodendroglial cells

Journal of Neuroscience Methods, Aug 1, 2009

a b s t r a c t OLN-93 cells, a cell line established from spontaneously transformed rat brain gl... more a b s t r a c t OLN-93 cells, a cell line established from spontaneously transformed rat brain glial cultures, are used as a model for oligodendrocytes. These cells are known to undergo morphological changes upon serum deprivation. The objective of the present study is to investigate a possible correlation between these morphological changes and (1) the loss or gain of oligodendrocyte markers and (2) the electrophysiological properties of these cells. Using RT-PCR and immunocytochemistry, we demonstrate that the OLN-93 cell line expresses a broad range of markers (NG2, CNP, MAG, MOG) both when cultured in medium containing 10% or 0.5% fetal calf serum. Whole-cell patch-clamp recordings demonstrate that, regardless of the culture conditions, OLN-93 cells mainly express delayed-rectifying K + currents, a characteristic of immature oligodendrocytes. These currents are in part mediated by the shaker family of voltage-gated potassium channels. Kv1.1 and Kv1.3-expression are present at the mRNA and at the protein levels, and functional evidence for Kv1.3 mediated currents was obtained by using the selective blocker margatoxin. Under low serum conditions, OLN-93 cells exhibit differentiation-like morphological changes. However, we provide evidence that these morphological modifications do not necessarily correlate with biochemical or functional changes. Based on these data, we conclude that the OLN-93 cell line can be situated at a developmental stage between a late pre-oligodendrocyte and a late immature oligodendrocyte, regardless of serum concentration.

Research paper thumbnail of Atomic frequency standard based upon coherent population trapping

Research paper thumbnail of Optically pumped atomic frequency standard

Research paper thumbnail of Resistance of Concrete to Freezing and Thawing

key words: aggregate D-cracking durability factor freezing and thawing modal analysis portland ce... more key words: aggregate D-cracking durability factor freezing and thawing modal analysis portland cement concrete quality factor resonance frequency Strategic Highway Research Program

Research paper thumbnail of Recognition of jumping patterns in volleyball after traditional and differential strength training by means of artificial neural nets

Research paper thumbnail of Handwriting acquisition in primary school by means of the differential learning approach *

The acquisition of handwriting is one of the mile-stones within the development of humans for be-... more The acquisition of handwriting is one of the mile-stones within the development of humans for be-coming social interactive beings. As handwriting is a movement skill, analogies to traditional ap-proaches in teaching sports skills are observable. Traditionally, children are taught to form letters with the correct sequence of strokes from the be-ginning. Thereby instructions include detailed pre-scriptions for pen, pen hold, hand movement and body position. In contrast, the differential learn-ing approach suggests stochastic perturbations and information on the difference of two subsequent movements as basis for learning. The aim of the present study is to transfer the differential learn-ing approach on handwriting acquisition in primary school. Two groups of 11 first-graders (6.8 ± 0.63 years) participated in a pre-posttest design with reten-tion and transfer test. The test included 23 tasks on symbol, pattern, character, word, and sentence level and was executed on a digitizing tabl...

Research paper thumbnail of Stochastic perturbations in athletic field events enhance skill acquisition

Research paper thumbnail of Dynamics and organization of alpha3-containing glycine receptors using single molecule detection

The Glycine receptor (GlyR) is a chloride permeable ligand gated ion channel and that can mediate... more The Glycine receptor (GlyR) is a chloride permeable ligand gated ion channel and that can mediate synaptic inhibition. Due to a possible involvement in the pathophysiology of temporal lobe epilepsy,the different properties of GlyRs containing alpha3L and K subunit isoforms are currently investigated. Previous characterizaions of homomeric receptors consisting of these isoforms have shown a difference in their electrophysiological properties and their membrane distribution as observed by diffraction-limited fluorescence microscopy. We studied these isoforms, when separately expressed in tranfected HEK 293T cells, by using single molecule tracking (SMT) in living cells and direct stochastic optical reconstruction microscopy (dSTORM) on fixated cells. For both techniquest the GlyRs are stained using a primary antibody directly labeled with Alexa Fluor dyes. The dSTORM experiments support the observation that the alpha3L GlyR are clustered, while the alpha3K GlyRs are more uniformly spr...

Research paper thumbnail of Coherent Population Trapping and Intensity Optical Pumping: On Their Use in Atomic Frequency Standards

Frequency Standards and Metrology - Proceedings of the 6th Symposium, 2002

The paper summarizes the relative advantages and disadvantages of Coherent Population Trapping (C... more The paper summarizes the relative advantages and disadvantages of Coherent Population Trapping (CPT) and Intensity Optical Pumping (IOP) for the implementation of a passive atomic frequency standard. The paper outlines the basic principles common to both CPT and IOP when ...

Research paper thumbnail of Increase in Escherichia coli inoculum dose accelerates CD8+ T-cell trafficking in the primiparous bovine mammary gland

Journal of dairy science, 2008

Although migration of leukocytes into the mammary gland is pivotal for a cow's response again... more Although migration of leukocytes into the mammary gland is pivotal for a cow's response against intramammary invading pathogens, the contribution of lymphocyte subsets to this response remains unclear. To investigate the dynamics of lymphocyte populations during Escherichia coli mastitis, T-lymphocyte subsets, CD4+/CD8+ ratio, CD21+ cells, and lymphoproliferation were studied in blood and milk of primiparous cows exposed to different quantities of bacteria. The cows were intramammarily inoculated with 10(4) cfu of E. coli (group A) and 10(6) cfu (group B). Compared with group A, a much greater number of lymphocytes migrated into the infected quarters at postinfection hour (PIH) 6 to 24 in group B, and the CD8+ cells were the first-recruited T cells in the milk. There was a significant decline in the CD4+/CD8+ ratios at PIH 6 to 24 in group B. The decrease of CD4+/CD8+ ratios at PIH 6 to 24 resulted mainly from greater CD8+ cell concentrations in milk. In contrast, at PIH 72, CD4...

Research paper thumbnail of The coherent population trapping passive frequency standard

Conference on Precision Electromagnetic Measurements, 2002

Coherent population trapping in alkali atoms has opened a new avenue in the implementation of ato... more Coherent population trapping in alkali atoms has opened a new avenue in the implementation of atomic frequency standards having promising characteristics for field use. The paper reviews the state of the art in this subject and describes recent results obtained in the case of a passive Rb standard implemented using such an approach.

Research paper thumbnail of Glycine enhances microglial intracellular calcium signaling. A role for sodium-coupled neutral amino acid transporters

Pflügers Archiv - European Journal of Physiology, 2011

The inhibitory neurotransmitter glycine is known to enhance microglial nitric oxide production. H... more The inhibitory neurotransmitter glycine is known to enhance microglial nitric oxide production. However, up to now, the mechanism is undocumented. Since calcium is an important second messenger in both immune and glial cells, we studied the effects of glycine on intracellular calcium signaling. We found that millimolar concentrations of glycine enhance microglial intracellular calcium transients induced by 100 μM ATP or by 500 nM thapsigargin. This modulation was unaffected by the glycine receptor antagonist strychnine and could not be mimicked by glycine receptor agonists such as taurine or β-alanine, indicating glycine receptor independency. The modulation of calcium responses could be mimicked by several structurally related amino acids (e.g., serine, alanine, or glutamine) and was inhibited in the presence of the neutral amino acid transporter substrate α-aminoisobutyric acid (AIB). We correlated these findings to immunofluorescence glycine uptake experiments which showed a clear glycine uptake which was inhibited by AIB. Furthermore, all amino acids that were shown to modulate calcium responses also evoked AIB-sensitive inward currents, mainly carried by sodium, as demonstrated by patch clamp experiments. Based on these findings, we propose that sodium-coupled neutral amino acid transporters are responsible for the observed glycine modulation of intracellular calcium responses.

Research paper thumbnail of Cell proliferation monitoring by multiplexed electrochemical impedance spectroscopy on microwell assays

Physica Status Solidi C: Current Topics in Solid State Physics, Vol 10, No 5, 2013

ABSTRACT Cell proliferation can be monitored by a wide range of well-established techniques. Most... more ABSTRACT Cell proliferation can be monitored by a wide range of well-established techniques. Most of the principles used rely on optical, single end-point methods, often involving the use of absorbent, fluorescent or luminescent compounds. These additives can interfere with the cell growth, thus producing distorted results. Electrochemical impedance spectroscopy provides a solution for this problem and enables continuous monitoring without interference. However equipment for this measurement technique is often bulky, highly expensive and lacks multichannel features. This paper presents a low-cost, compact hardware platform optimized for proliferation measurements, together with custom software to ease interpretation and physical modelling of data. Performance is demonstrated and measurement parameters are fine-tuned for three commonly used cell types in proliferation measurements. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)