The vulnerability of calretinin-containing hippocampal interneurons to temporal lobe epilepsy

This review focuses on the vulnerability of a special interneuron type—the calretinin (CR)-containing interneurons—in temporal lobe epilepsy (TLE). CR is a calcium-binding protein expressed mainly by GABAergic interneurons in the hippocampus. Despite their morphological heterogeneity, CR-containing interneurons form a distinct subpopulation of inhibitory cells, innervating other interneurons in rodents and to some extent principal cells in the human. Their dendrites are strongly connected by zona adherentiae and presumably by gap junctions both in rats and humans. CR-containing interneurons are suggested to play a key role in the hippocampal inhibitory network, since they can effectively synchronize dendritic inhibitory interneurons. The sensitivity of CR-expressing interneurons to epilepsy was discussed in several reports, both in animal models and in humans. In the sclerotic hippocampus the density of CR-immunopositive cells is decreased significantly. In the non-sclerotic hippocampus, the CR-containing interneurons are preserved, but their dendritic tree is varicose, segmented, and zona-adherentia-type contacts can be less frequently observed among dendrites. Therefore, the dendritic inhibition of pyramidal cells may be less effective in TLE. This can be partially explained by the impairment of the CR-containing interneuron ensemble in the epileptic hippocampus, which may result in an asynchronous and thus less effective dendritic inhibition of the principal cells. This phenomenon, together with the sprouting of excitatory pathway axons and enhanced innervation of principal cells, may be involved in seizure generation. Preventing the loss of CR-positive cells and preserving the integrity of CR-positive dendrite gap junctions may have antiepileptic effects, maintaining proper inhibitory function and helping to protect principal cells in epilepsy

A fagyasztott zöldségek fogyasztási preferenciáinak vizsgálata

A magyar hűtÅ‘ipar számára a külföldi piacokon való értékesítés nagy jelentÅ‘ségű. A hűtÅ‘ipar talán az egyetlen ágazat, melynek termelése minÅ‘ségileg sosem különült el az értékesítés piacai szerint, köszönhetÅ‘en annak, hogy a vertikumban a nemzetközi követelmények érvényesültek. A komplex vásárlói modellek elemzését követÅ‘en megállapítható, hogy az ízesített termékeket leginkább az aktív szellemi foglalkozásúak részesítik elÅ‘nyben, akik átlag feletti jövedelemmel rendelkeznek. Az ízesített termékek és a vegyes összetevÅ‘jű (mix) termékek tipikus vásárlója között nem tapasztalható jelentÅ‘s eltérés. A vizsgálat eredményei alapján az a következtetés vonható le, hogy az egy összetevÅ‘jű termékek vásárlói között a legalacsonyabb a férfiak és a legmagasabb a nÅ‘k, valamint a középfokú végzettségűek aránya. --------------------------------------------- The marketing of products in foreign markets is of paramount importance for the Hungarian deep freeze industry. The deep freeze industry may be the only sector where the quality of products has never varied according to the target market, as the product chain is ruled by international requirements. The analysis of complex customer models leads us to conclude that flavoured products were favoured by mostly persons of white collar vocations, who have an above average in come. No significant discrepancies were perceived between the typical customers of flavoured products and products of mixed ingredients. Based on the results of the analysis it can be stated that among the customers choosing products consisting of one component only, the ratio of men was lowest whereas that of women and persons having secondary education was highest.mélyhűtÅ‘ipar, fagyasztott élelmiszer, export, fogyasztói magatartás, vásárlási szokások, deep freeze industry, frozen food, export, consumer behaviour, customer habits, Consumer/Household Economics, Marketing,

The transport of cosmic rays in self-excited magnetic turbulence

The process of diffusive shock acceleration relies on the efficacy with which hydromagnetic waves can scatter charged particles in the precursor of a shock. The growth of self-generated waves is driven by both resonant and non-resonant processes. We perform high-resolution magnetohydrodynamic simulations of the non-resonant cosmic-ray driven instability, in which the unstable waves are excited beyond the linear regime. In a snapshot of the resultant field, particle transport simulations are carried out. The use of a static snapshot of the field is reasonable given that the Larmor period for particles is typically very short relative to the instability growth time. The diffusion rate is found to be close to, or below, the Bohm limit for a range of energies. This provides the first explicit demonstration that self-excited turbulence reduces the diffusion coefficient and has important implications for cosmic ray transport and acceleration in supernova remnants.Comment: 8 pages, 8 figures, accepted for publication in MNRA

Surface-exposed positions in the transmembrane helices of the lactose permease of Escherichia coli determined by intermolecular thiol cross-linking

Intermolecular thiol cross-linking was used to determine surface-exposed positions in 250 lactose permease mutants containing single-Cys replacements in each transmembrane helix. Significant cross-linking of monomers to produce homodimers is observed in nine mutants with a 5-Å-long cross-linking agent containing bis-methane thiosulfonate reactive groups [position 78 (helix III); positions 185, 186, and 187 (helix VI); positions 263, 275, and 278 (helix VIII); and positions 308 (helix IX) and 398 (helix XII)]. The results are consistent with a current helix-packing model of the permease. Seven of the nine mutants that exhibit intermolecular cross-linking are located at or near the cytoplasmic ends of transmembrane helices; two are near periplasmic ends. The results suggest that only those Cys replacements accessible from the aqueous phase and not from the hydrophobic core of the membrane are susceptible to cross-linking because of the much higher reactivity of the thiolate anion relative to the thiol. Single-Cys mutants at positions 278 (helix VIII) and 398 (helix XII), which are located in opposite sides of the 12-helix bundle, exhibit similar rates of cross-linking with sigmoid kinetics. Furthermore, cross-linking is markedly decreased at 0°C, suggesting that lateral diffusion of the permease within the plane of the membrane is important for intermolecular cross-linking. The findings confirm previous observations indicating that intermolecular cross-linking is a stochastic process resulting from random collisions and support a number of other lines of evidence that lactose permease is a monomer

Pathobiology of human intracranial saccular aneurysms

Intracranial saccular aneurysms develop in the course of life in a few percent of the total population. Usually they grow slowly, remain unnoticed, but their rupture induces subarachnoid bleeding with fatal or devastating consequences. Several theories have been constructed to explain the pathomechanism of aneurysm development and rupture. Here these theories will be reviewed. The very complicated blood flow pattern in arteries at the human cerebral base, instability of collateral circulation as well as blood pressure changes can disturb normal, laminar blood flow at bifurcations. With endothelial damage, integrity of basal lamina and internal elastic lamina will also be affected. Evagination of the thin wall occurs with increasing stresses on medial elements. Any pathological factor affecting molecular structures joining connective tissue components with each other, or with the cellular structures, will promote the evagination process. With further enlargement of the sack, increasing mechanical forces make the presence of smooth muscle cells impossible in the wall. When this happens, the ability to rearrange, reorientate connective tissue fibers with the aid of active forces will be lost. Passive rearrangement of fiber structure governed by distending forces, thinning of the wall will be the result, unavoidably leading to the fatal outcome. We can conclude that current hypotheses of human intracranial saccular aneurysm development are not necessarily contradictory. Probably, they describe different factors promoting separate phases in the aneurysm development.Biomedical Reviews 2000; 11: 53-61