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Brain inflammation plays a central role in multiple sclerosis (MS). Besides lymphocytes, the astroglia and microglia mainly contribute to the cellular composition of the inflammatory infiltrate in MS lesions. Several studies were able to demonstrate that cortical lesions are characterized by lower levels of inflammatory cells among activated microglia/macrophages. The underlying mechanisms for this difference, however, remain to be clarified. In the current study, we compared the kinetics and extent of microglia and astrocyte activation during early and late cuprizone-induced demyelination in the white matter tract corpus callosum and the telencephalic gray matter. Cellular parameters were related to the expression profiles of the chemokines Ccl2 and Ccl3 . We are clearly able to demonstrate that both regions are characterized by early oligodendrocyte stress/apoptosis with concomitant microglia activation and delayed astrocytosis. The extent of microgliosis/astrocytosis appeared to be greater in the subcortical white matter tract corpus callosum compared to the gray matter cortex region. The same holds true for the expression of the key chemokines Ccl2 and Ccl3 . The current study defines a model to study early microglia activation and to investigate differences in the neuroinflammatory response of white vs. gray matter.

Excessive low-affinity Na+ uptake is toxic to the growth of glycophytic plants. Recently, several reports have suggested that the interaction between K+ and Na+ uptake might represent a key factor in determining the Na+ tolerance of plants. We investigated the effects of K+ starvation on Na+ and K+ uptake mechanisms in the plasma membrane of wheat (Triticum aestivum L.) root cortex cells using the patch-clamp technique. Unexpectedly, K+ starvation of wheat seedlings was found to enhance the magnitude and frequency of occurrence of time-dependent inward-rectifying K+ channel currents ($\\text{I}_{\\text{K}}{}^{+}{}_{\\text{in}}$). We examined whether the transcription of a wheat root $\\text{K}^{+}{}_{\\text{in}}$ channel gene is induced by K+ starvation. A cDNA coding for a wheat root K+ channel homolog, TaAKT1 (accession no. AF207745), was isolated. TaAKT1 mRNA levels were up-regulated in roots in response to withdrawal of K+ from the growth medium. Furthermore, K+ starvation caused an enhancement of instantaneous Na+ currents ($\\text{I}_{\\text{Na}}{}^{+}$). Electrophysiological analyses suggested that $\\text{I}_{\\text{K}}{}^{+}{}_{\\text{in}}$ and $\\text{I}_{\\text{Na}}{}^{+}$ are not mediated by the same transport protein based on: (a) different activation curves, (b) different time dependencies, (c) different sensitivities to external Ca2+, and (d) different cation selectivities. These data implicate a role for $\\text{I}_{\\text{Na}}{}^{+}$ in Na+ uptake and stress during K+ starvation, and indicate that $\\text{K}^{+}{}_{\\text{in}}$ channels may contribute to K+-starvation-induced K+ uptake in wheat roots.

The activities of the major ion pathways in the plasma membranes of plants are sensitive to the membrane voltage, V. Therefore, these 'electroenzymes' interact with each other via the free running voltage under physiological conditions. A physical background is given here, of how to calculate these interactions on the basis of experimental data on these electroenzymes. Simplifying model calculations with five major electroenzymes from plant cells (H⁺ pump, inward and outward rectifying channels for K⁺, a Cl⁻ channel, and a 2H⁺/Cl⁻ symporter) show that osmotic relations are balanced in the long-term not by an appropriate steady-state, but by alternation between a state of salt uptake at V < < EK (the Nernst equilibrium voltage for K⁺ diffusion) and a state of salt loss at V > EK. Several specific properties of the model are discussed numerically, e.g. minimum configuration for oscillations (with two electroenzymes), temperature-compensation, the physiological impact of fast gating in plant membranes, and solution of possible paradoxes, such as flux stimulation by conductance inhibition.

Heterotrimeric GTPases (G-proteins) are implicated in many cellular signalling processes. In plants, a function of a specific G-protein has only recently been characterized. A cDNA clone encoding a G-protein [alpha]-subunit was isolated from tobacco (Nicotiana tabacum L.). The deduced amino acid sequence of this [alpha]-subunit (NtGP[alpha]1) has 91% homology to GP[alpha]1 from Arabidopsis thaliana. Sequence comparisons with other plant G-proteins show that these two [alpha]-subunits belong to the only class of plant G-proteins known to date. The NtGP[alpha]1 cDNA was placed under the control of the CaMV 35S promoter both in sense and antisense orientation. These constructs were stably transformed into tobacco plants. As shown by patch-clamp experiments, mesophyll protoplasts of transformed tobacco plants over-expressing NtGP[alpha]1 sense or antisense RNA exhibited enhanced plasmalemma K<+< conductances compared to the wild type. By contrast, mesophyll protoplasts of transformed tobacco plants expressing the cholera toxin A1-subunit, a G-protein activator, exhibited a reduced plasmalemma K<+< conductance. These results indicate for the first time a role of a specific G-protein in the regulation of K<+< channels. Keywords:G-protein, cloning, antisense, K<+< channel regulation, Nicotiana tabacum.

An experimental study of the normalized three-jet rate of b quark events with respect to light quarks events (light=ℓ≡u,d,s) has been performed using the CAMBRIDGE and DURHAM jet algorithms. The data used were collected by the DELPHI experiment at LEP on the Z peak from 1994 to 2000. The results are found to agree with theoretical predictions treating mass corrections at next-to-leading order. Measurements of the b quark mass have also been performed for both the b pole mass: Mb and the b running mass: mb(MZ). Data are found to be better described when using the running mass. The measurement yields: \\(m_b(M_Z)=2.85\\pm0.18 (\\text{stat}) \\pm0.13 (\\text{exp}) \\pm0.19 (\\text{had}) \\pm0.12 (\\text{theo}) \\text{GeV}/c^2.\\)for the CAMBRIDGE algorithm.This result is the most precise measurement of the b mass derived from a high energy process. When compared to other b mass determinations by experiments at lower energy scales, this value agrees with the prediction of quantum chromodynamics for the energy evolution of the running mass. The mass measurement is equivalent to a test of the flavour independence of the strong coupling constant with an accuracy of 7 ‰.

Searches for H Z production with the Higgs boson decaying into an invisible final state were performed using the data collected by the DELPHI experiment at centre-of-mass energies between 188 GeV and 209 GeV. Both hadronic and leptonic final states of the Z boson were analysed. In addition to the search for a heavy Higgs boson, a dedicated search for a light Higgs boson down to 40 GeV/c2 was performed. No signal was found. Assuming the Standard Model HZ production cross-section, the mass limit for invisibly decaying Higgs bosons is 112.1 GeV/c2 at 95% confidence level. An interpretation in the Minimal Supersymmetric extension of the Standard Model (MSSM) and in a Majoron model is also given.

Hadronic event shape distributions are determined from data in e+e- collisions between 183 and 207 GeV. From these the strong coupling alpha_(s) is extracted in O(alpha_(s)²), NLLA and matched O(alpha_(s)²)+NLLA theory. Hadronisation corrections evaluated with fragmentation model generators as well as an analytical power ansatz are applied. Comparing these measurements to those obtained at and around M_(Z) allows a combined measurement of alpha_(s) from all DELPHI data and a test of the energy dependence of the strong coupling.

Measurements are presented of R_(b), the ratio of the b bbar cross-section to the q qbar cross-section in e+e- collisions, and the forward-backward asymmetry Aᵇ_(F)B at twelve energy points in the range sqrt(s) = 130-207 GeV. These results are found to be consistent with the Standard Model expectations. The measurements are used to set limits on new physics scenarios involving contact interactions.