Zinc transporter-3 (ZnT-3), a member of a growing family of mammalian zinc transporters, is expressed in regions of the brain that are rich in histochemically reactive zinc (as revealed by the Timm's ...stain), including entorhinal cortex, amygdala, and hippocampus. ZnT-3 protein is most abundant in the zinc-enriched mossy fibers that project from the dentate granule cells to hilar and CA3 pyramidal neurons. We show here by electron microscopy that ZnT-3 decorates the membranes of all clear, small, round synaptic vesicles (SVs) in the mossy fiber boutons of both mouse and monkey. Furthermore, up to 60-80% of these SVs contain Timm's-stainable zinc. The coincidence of ZnT-3 on the membranes of SVs that accumulate zinc, and its homology with known zinc transporters, suggest that ZnT-3 is responsible for the transport of zinc into SVs, and hence for the ability of these neurons to release zinc upon excitation.
The spectral and spatial behavior of monolithically integrated distributed-feedback tapered master-oscillator power amplifiers emitting around 973 nm is experimentally and theoretically investigated. ...We demonstrate a good agreement between experiments and theory and analyze peculiarities of the observed dynamical regimes.
Genetic influences contribute to susceptibility to seizures and to excitotoxic injury, but it is unclear if/how these susceptibilities are linked. This study assessed the impact of genetic background ...on mouse strain seizure susceptibility, seizure phenotype, mortality, and hippocampal histopathology. A subcutaneous (s.c.) kainic acid multiple injection protocol was developed. Five mouse strains were tested: a and b) C57BL/6J and 129/SvJ, strains commonly used in gene targeting experiments; c) C3HeB/FeJ, a strain with reported sensitivity to the convulsant effects of kainic acid (KA); d) 129/SvEms, a strain reportedly susceptible to hippocampal excitotoxic cell death; and e) a mixed genetic background strain (129/SvJXC57BL/6J) from which targeted gene deletion experiments have been carried out. Histopathological features were examined at early (7–10 day), delayed (2–4 month), and late (6–13 month) time points.
Mouse background strains can be genetically segregated based on excitotoxin sensitivity, seizure phenotype, mortality, and hippocampal histopathology. When injected with KA, C3HeB/FeJ and C57BL/6J strains were resistant to cell death and synaptic reorganization despite severe behavioral seizures, while 129/SvEms mice developed marked pyramidal cell loss and mossy fiber sprouting despite limited seizure activity. The mixed background 129/SvJXC57BL/6J group exhibited features of both parental strains. In the mouse strains tested, the duration or severity of seizure activity was not predictive of subsequent hippocampal pyramidal cell death and/or synaptic reorganization. Unlike rats, mice exhibiting prolonged high-grade KA-induced seizure activity did not develop subsequent spontaneous behavioral seizures.
Distributed-feedback ridge-waveguide lasers emitting around 670 nm have been fabricated and experimentally characterised. Wavelength stabilisation is provided by 40th Bragg order surface gratings ...dry-etched into the p-GaAs–AlGaAs–AlGaInP layer structure. The large grating period of 4.2 µm allows the injection of the current between the grooves of the grating without sacrificing the electrical and optical properties noticeably. The 1.5 mm long devices achieve an output power of 50 mW at an injection current of 180 mA. The side mode suppression ratio is 50 dB at 150 mA.
There is a high correlation between pediatric epilepsies and neuronal migration disorders. What remains unclear is whether there are intrinsic features of the individual dysplastic cells that give ...rise to heightened seizure susceptibility, or whether these dysplastic cells contribute to seizure activity by establishing abnormal circuits that alter the balance of inhibition and excitation. Mice lacking a functional p35 gene provide an ideal model in which to address these questions, because these knock-out animals not only exhibit aberrant neuronal migration but also demonstrate spontaneous seizures. Extracellular field recordings from hippocampal slices, characterizing the input-output relationship in the dentate, revealed little difference between wild-type and knock-out mice under both normal and elevated extracellular potassium conditions. However, in the presence of the GABA(A) antagonist bicuculline, p35 knock-out slices, but not wild-type slices, exhibited prolonged depolarizations in response to stimulation of the perforant path. There were no significant differences in the intrinsic properties of dentate granule cells (i.e., input resistance, time constant, action potential generation) from wild-type versus knock-out mice. However, antidromic activation (mossy fiber stimulation) evoked an excitatory synaptic response in over 65% of granule cells from p35 knock-out slices that was never observed in wild-type slices. Ultrastructural analyses identified morphological substrates for this aberrant excitation: recurrent axon collaterals, abnormal basal dendrites, and mossy fiber terminals forming synapses onto the spines of neighboring granule cells. These studies suggest that granule cells in p35 knock-out mice contribute to seizure activity by forming an abnormal excitatory feedback circuit.
High-Brightness Quantum Well Tapered Lasers Sumpf, B.; Hasler, K.-H.; Adamiec, P. ...
IEEE journal of selected topics in quantum electronics,
05/2009, Letnik:
15, Številka:
3
Journal Article
Recenzirano
High-power quantum well lasers with high brightness in the spectral range between 650 nm and 1080 nm will be presented. Improved layer structures with a narrow vertical far-field divergence down to ...angles of 15deg (full-width at half-maximum) were developed. For these layer structures, optimized tapered lasers were processed to achieve laterally a nearly diffraction-limited beam quality with beam propagation factors smaller than 2. Depending on the emission wavelength, the tapered devices reach an output power up to 12 W and a brightness of 1 GWmiddotcm -2 middotsr -1 .
Summary
Purpose: Mice lacking the Kv1.1 potassium channel α subunit encoded by the Kcna1 gene develop recurrent behavioral seizures early in life. We examined the neuropathological consequences of ...seizure activity in the Kv1.1−/− (knock‐out) mouse, and explored the effects of injecting a viral vector carrying the deleted Kcna1 gene into hippocampal neurons.
Methods: Morphological techniques were used to assess neuropathological patterns in hippocampus of Kv1.1−/− animals. Immunohistochemical and biochemical techniques were used to monitor ion channel expression in Kv1.1−/− brain. Both wild‐type and knockout mice were injected (bilaterally into hippocampus) with an HSV1 amplicon vector that contained the rat Kcna1 subunit gene and/or the E. coli lacZ reporter gene. Vector‐injected mice were examined to determine the extent of neuronal infection.
Results: Video/EEG monitoring confirmed interictal abnormalities and seizure occurrence in Kv1.1−/− mice. Neuropathological assessment suggested that hippocampal damage (silver stain) and reorganization (Timm stain) occurred only after animals had exhibited severe prolonged seizures (status epilepticus). Ablation of Kcna1 did not result in compensatory changes in expression levels of other related ion channel subunits. Vector injection resulted in infection primarily of granule cells in hippocampus, but the number of infected neurons was quite variable across subjects. Kcna1 immunocytochemistry showed “ectopic” Kv1.1 α channel subunit expression.
Conclusions:
Kcna1 deletion in mice results in a seizure disorder that resembles—electrographically and neuropathologically—the patterns seen in rodent models of temporal lobe epilepsy. HSV1 vector‐mediated gene transfer into hippocampus yielded variable neuronal infection.
We compare 980-nm distributed-feedback ridge-waveguide lasers having cavity lengths of 1.5 and 3 mm. The maximum single-mode output powers are 500 and 700 mW, respectively. The full-width at ...half-maximum of the vertical far-field profile is only 22/spl deg/ due to a superlarge optical cavity.
•Approach for use of scenarios dealing with both waste management and energy issues.•Overall scenarios for the common project and sub-scenarios in parts of the project.•Combining different types of ...scenarios to the tools of different disciplines.•Use of explorative external scenarios based on marginals for consequential LCA.
Development and use of scenarios for large interdisciplinary projects is a complicated task. This article provides practical examples of how it has been carried out in two projects addressing waste management and energy issues respectively. Based on experiences from the two projects, recommendations are made for an approach concerning development of scenarios in projects dealing with both waste management and energy issues. Recommendations are given to develop and use overall scenarios for the project and leave room for sub-scenarios in parts of the project. Combining different types of scenarios is recommended, too, in order to adapt to the methods and tools of different disciplines, such as developing predictive scenarios with general equilibrium tools and analysing explorative scenarios with energy system analysis tools. Furthermore, as marginals identified in differing future background systems determine the outcomes of consequential life cycle assessments (LCAs), it is considered advisable to develop and use explorative external scenarios based on possible marginals as a framework for consequential LCAs. This approach is illustrated using an on-going Danish research project.
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