Neuronal and astroglial correlates underlying spatiotemporal Intrinsic Optical Signal in the rat hippocampal slice

Widely used for mapping afferent activated brain areas in vivo, the label-free intrinsic optical signal (IOS) is mainly ascribed to blood volume changes subsequent to glial glutamate uptake. By contrast, IOS imaged in vitro is generally attributed to neuronal and glial cell swelling, however the relative contribution of different cell types and molecular players remained largely unknown. We characterized IOS to Schaffer collateral stimulation in the rat hippocampal slice using a 464-element photodiode-array device that enables IOS monitoring at 0.6 ms time-resolution in combination with simultaneous field potential recordings. We used brief half-maximal stimuli by applying a medium intensity 50 Volt-stimulus train within 50 ms (20 Hz). IOS was primarily observed in the str. pyramidale and proximal region of the str. radiatum of the hippocampus. It was eliminated by tetrodotoxin blockade of voltage-gated Na+ channels and was significantly enhanced by suppressing inhibitory signaling with gamma-aminobutyric acid(A) receptor antagonist picrotoxin. We found that IOS was predominantly initiated by postsynaptic Glu receptor activation and progressed by the activation of astroglial Glu transporters and Mg2+-independent astroglial N-methyl-D-aspartate receptors. Under control conditions, role for neuronal K+/Cl- cotransporter KCC2, but not for glial Na+/K+/Cl- cotransporter NKCC1 was observed. Slight enhancement and inhibition of IOS through non-specific Cl- and volume-regulated anion channels, respectively, were also depicted. High-frequency IOS imaging, evoked by brief afferent stimulation in brain slices provide a new paradigm for studying mechanisms underlying IOS genesis. Major players disclosed this way imply that spatiotemporal IOS reflects glutamatergic neuronal activation and astroglial response, as observed within the hippocampus. Our model may help to better interpret in vivo IOS and support diagnosis in the future

Gépjármű-kommunikációs hálózatok : Automotive communication networks

The use of the control units has changed communicaton networks. The CAN network was created to speed up communication between control units and redused the number of wires. The reduction in the number of wires has made is much easier to find faulty parts. Standardized networks have opend new gates for development and more and more people have recognized its benetfits.  Kivonat Az új vezérlőegységek használata megváltoztatta a kommunikációs hálózatokat. A CAN hálózat azért jött létre, hogy felgyorsuljon a kommunikáció a vezérlőegységek között és csökkenjenek a vezetékek száma. A vezetékek számának csökkenése jelentősen megkönnyítette a hibás alkatrészek megtalálását. Aszabványosított hálózatok új kapukat nyitottak meg a fejlődé előtt és egyre többen ismerték fel előnyét

Poor in vivo efficacy of caspofungin, micafungin and amphotericin B against wild-type Candida krusei clinical isolates does not correlate with in vitro susceptibility results

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Polyamidoamine dendrimer impairs mitochondrial oxidation in brain tissue

Background: The potential nanocarrier polyamidoamine (PAMAM) generation 5 (G5-NH2) dendrimer has been shown to evoke lasting neuronal depolarization and cell death in a concentration-dependent manner. In this study we explored the early progression of G5-NH2 action in brain tissue on neuronal and astroglial cells.Results: In order to describe early mechanisms of G5-NH2 dendrimer action in brain tissue we assessed G5-NH2 trafficking, free intracellular Ca2+ and mitochondrial membrane potential (ΨMITO) changes in the rat hippocampal slice by microfluorimetry. With the help of fluorescent dye conjugated G5-NH2, we observed predominant appearance of the dendrimer in the plasma membrane of pyramidal neurons and glial cells within 30 min. Under this condition, G5-NH2 evoked robust intracellular Ca2+ enhancements and ΨMITO depolarization both in pyramidal neurons and astroglial cells. Intracellular Ca2+ enhancements clearly preceded ΨMITO depolarization in astroglial cells. Comparing activation dynamics, neurons and glia showed prevalence of lasting and transient ΨMITO depolarization, respectively. Transient as opposed to lasting ΨMITO changes to short-term G5-NH2 application suggested better survival of astroglia, as observed in the CA3 stratum radiatum area. We also showed that direct effect of G5-NH2 on astroglial ΨMITO was significantly enhanced by neuron-astroglia interaction, subsequent to G5-NH2 evoked neuronal activation.Conclusion: These findings indicate that the interaction of the PAMAM dendrimer with the plasma membrane leads to robust activation of neurons and astroglial cells, leading to mitochondrial depolarization. Distinguishable dynamics of mitochondrial depolarization in neurons and astroglia suggest that the enhanced mitochondrial depolarization followed by impaired oxidative metabolism of neurons may be the primary basis of neurotoxicity. © 2013 Nyitrai et al.; licensee BioMed Central Ltd

A Pasteurellaceae család egyes emlőspatogén fajainak összehasonlító vizsgálata = Comparative examination of some mammal pathogens of the Family Pasteurellaceae

A Mannheimia haemolytica, a Histophilus somni és az Actinobacillus pleuropneumoniae az összehasonlító vizsgálatát végeztük el szénforrás-hasznosításon alapuló anyagcsere-ujjlenyomat meghatározása és pulzáló mezejű gélelektroforézis (PFGE) segítségével. Összesen 100 H. somni, 56 M. haemolytica és 73 A. pleuropneumoniae törzs szénforrás-hasznosítását vizsgáltuk. Valamennyi H. somni törzs hasznosítani tudott 2, M. haemolytica 5 és A. pleuropneumoniae törzs 20 szénforrást, míg a törzsek legalább 90%-a felhasznált további 5, 13 illetve 11 szénforrást. Ennek alapján a különböző állatfajokból és kórformákból származó H. somni törzseket meg lehetett különböztetni, míg a M. haemolytica és az A. pleuropneumoniae törzsek egységesebbek voltak. A PFGE vizsgálatok során a különböző állatfajból származó H. somni törzsek jól elkülönültek egymástól. A genitális kommenzális törzsek nagyobb genetikai diverzitást mutattak, mint az invazív fertőzésből izolált törzsek. Az A. pleuropneumoniae 2-es biocsoporton belül a genetikai különbség sokkal kisebb volt, mint az 1-es biocsoportba tartozó törzsek között. Az 1-es biotípuson belül 7 genetikai csoportot különböztettünk meg. Ezekbe a csoportokba általában egyazon szerotípusba sorolható törzsek tartoztak. A M. haemolytica a különböző szerotípusba tartozó izolátumai általában elkülönültek. A PFGE módszer alkalmas az egyazon szerotípusba tartozó törzsek megkülönböztetésére. Egy állományon belül a genetikai diverzitás nem jellemző a M. haemolytica-ra. | Comparative examination of three species of veterinary importance of the Family Pasteurellaceae, Mannheimia haemolytica, Histophilus somni and Actinobacillus pleuropneumonia was carried out using a metabolic fingerprinting method based on carbon source utilisation and pulsed field gel electrophoresis (PFGE). Carbon source utilisation of 100 H. somni, 56 M. haemolytica and 73 A. pleuropneumoniae strains was examined. All H. somni strains could utilise 2, M. haemolytica 5 and A. pleuropneumoniae strains 20 carbon sources, while further 5, 13 and 11 carbon sources respectively were metabolised by at least 90% of the strains. H. somni strains from different species and diseases could be differentiated on the basis of metabolic fingerprinting, while M. haemolytica and A. pleuropneumoniae strains proved to be more uniform. The H. somni strains isolated from different species could be differentiated using PFGE. Higher genetic diversity was evident among commensals of the genitals than among strains isolated from invasive diseases. The genetic differences within biotype 2 of A. pleuropneumoniae was much lower than biotype 1. Seven genetic groups could be differentiated within biotype 1 of A. pleuropneumoniae. The same serotypes belonged to the same genetic group. Serotypes of M. haemolytica formed different clusters, differentiation of the strains within the same serotype could be done with PFGE. The genetic diversity of M. haemolytica within a herd was not common

Appearance of fast astrocytic component in voltage-sensitive dye imaging of neural activity.

BACKGROUND: Voltage-sensitive dye (VSD) imaging and intrinsic optical signals (IOS) are widely used methods for monitoring spatiotemporal neural activity in extensive networks. In spite of that, identification of their major cellular and molecular components has not been concluded so far. RESULTS: We addressed these issues by imaging spatiotemporal spreading of IOS and VSD transients initiated by Schaffer collateral stimulation in rat hippocampal slices with temporal resolution comparable to standard field potential recordings using a 464-element photodiode array. By exploring the potential neuronal and astroglial molecular players in VSD and IOS generation, we identified multiple astrocytic mechanisms that significantly contribute to the VSD signal, in addition to the expected neuronal targets. Glutamate clearance through the astroglial glutamate transporter EAAT2 has been shown to be a significant player in VSD generation within a very short (<5 ms) time-scale, indicating that astrocytes do contribute to the development of spatiotemporal VSD transients previously thought to be essentially neuronal. In addition, non-specific anion channels, astroglial K(+) clearance through Kir4.1 channel and astroglial Na(+)/K(+) ATPase also contribute to IOS and VSD transients. CONCLUSION: VSD imaging cannot be considered as a spatially extended field potential measurement with predominantly neuronal origin, instead it also reflects a fast communication between neurons and astrocytes

A stochastic approach for regional-scale surface water quality modeling

A methodology is proposed to calculate statistical average and standard deviation of long time water quality parameter series along a river network. The method considers the water network as a graph consisting of straight sessions and junctions. With a Taylor-series approximation, statistical values of an arbitrary point of the network can be calculated from upstream ones without the need to calculate the single downstream values. According to preliminary results of the first calculations on a pilot area, mean value of the downstream biological oxygen demand and the so called ‘transfer coefficient’ can be approximated with a relative accuracy of 10%