Auditory-evoked potentials as indicator of brain serotonergic activity--first evidence in behaving cats

Due to the increasing importance of the central serotonergic neurotransmission for pathogenetic concepts and as a target of pharmacotherapeutic interventions in psychiatry, reliable indicators of this system are needed. Several findings from basic and clinical research suggest that the stimulus intensity dependence of auditory evoked potentials (AEP) may be such an indicator of behaviorally relevant aspects of serotonergic activity (Hegerl and Juckel 1993, Biol Psychiatry 33:173-187). In order to study this relationship more directly, epidural recordings over the primary and secondary auditory cortex were conducted in chronically implanted cats under intravenous (i.v.) administration of drugs influencing the serotonergic and other modulatory systems (8-OH-DPAT, m-CPP, ketanserin, DOI, apomorphine, atropine, clonidine). The intensity dependence of the cat AEP component with the highest functional similarity to this of the N1/P2-component in humans was significantly changed by influencing 5-HT1a and 5-HT2 receptors, but not 5-HT1c receptors. This serotonergic modulation of the intensity dependence was only found for the primary auditory cortex which corresponds to the known different innervation of the primary and secondary auditory cortex by serotonergic fibers. Our study supports the idea that the intensity dependence of AEP could be a valuable indicator of brain serotonergic activity; however, this indicator seems to be of relative specificity because at least cholinergic effects on the intensity dependence were also observed.     

Schnelle Drehmomentregelung im gesamten Drehzahlbereich eines hochausgenutzten Drehfeldantriebs

Electrical Engineering - Das jeweilige maximale Drehmoment einer wechselrichtergespeisten Kurzschlußläufer-Asynchronmaschine ist durch die Begrenzung von Wechselrichter-Ausgangsstrom und...     

Involvement of phospholipid molecular species in controlling structural order of vertebrate brain synaptic membranes during thermal evolution

Fluorescence anisotropy parameter of [p-(6-phenyl)-1,3,5-hexatrienyl]phenyl-propionic acid (DPH-PA) and 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene (TMA-DPH) embedded in synaptic plasma membranes prepared from brains of cold (5°C) and warm (22°C) adapted fish (Cyprinus carpio L.), rat (Rattus norvegicus) and bird (Branta canadensis), was studied. Fatty acid composition of total lipids as well as molecular species composition of diacyl phosphatidylcholines and phosphatidylethanolamines was also determined. The amount of long-chain polyunsaturated fatty acids decreased with increasing body temperature. There was a nearcomplete compensation of membrane structural order for environmental/body tempeature over the evolutionary scale as seen by DPH-PA. Using TMA-DPH, the compensation was partial with rat and bird. Since DPH-PA and TMA-DPH differ in their charges, it is proposed, that the former reported membrane regions rich in cationic or zwitterionic (neutral) phospholipids and the latter, membrane regions rich in negatively charged phospholipids in the synaptic plasma membranes. Many different molecular species (20–25) of diacyl phosphatidylcholines and diacyl phosphatidylethanolamines were identified. The level of 16:0/22:6 phosphatidylcholine decreased while disaturated phosphatidylcholines increased with increase of environmental/body temperature from the fish through the bird. Level of 1-monoenoic 2-polyenoic phosphatidylethanolamines also decreased with an increase in environmental/body temperature. Experiments using vesicles made of mixed synthetic phosphatidylcholine vesicles (16:0/16:0, 16:0/18:1, 16:0/22:6 in various proportions) showed that increase in disaturated phosphatidylcholine species does not explain the observed complete adjustment of membrane structural order in synaptic plasma membranes. Change in level of 1-monoenoic, 2-polyenoic phosphatidylethanolamines might be one of the factors involved in controlling the biophysical properties of the membrane according to the temperature.     

Preliminary investigations of an amperometric oligosaccharide dehydrogenase-based electrode for the detection of glucose and some other low molecular weight saccharides

Biosensors for the determination of sugars were constructed using oligosaccharide dehydrogenase (ODH) and soluble phenazine methosulfate (PMS) or an osmium-based three-dimensional redox hydrogel. In the latter case the enzyme and poly(1-vinylimidazole) complexed with osmium (4,4'-dimethylbpy)2Cl were cross-linked with poly(ethylene glycol) diglycidyl ether. Both electrode configurations showed similar sensitivities for glucose in the range between 8 and 21 muAmM-1 cm-2. The responses for 10 mono and oligosaccharides were studied. There was no response for fructose. In the concentration range 0.1-20 mM the relative sensitivities were determined for arabinose (96%), xylose (3%), mannose (50%), galactose (11%), glucose (100%), maltose (24%), lactose (12%), cellobiose (34%) and maltotriose (10%).     

Time course of vinblastine-induced autophagocytosis and changes in the endoplasmic reticulum in murine pancreatic acinar cells: a morphometric and biochemical study

The time course of the vinblastine(-sulfate; 10 mg/kg body weight, single injection)-induced enlargement and subsequent regression of the autolysosomal compartment was studied by electron microscopic morphometrical and cell biochemical methods in order to gain information concerning some key problems of this major route of intralysosomal degradation of the cell's endogenous macromolecules and structures. Detailed analysis of the dynamics of the total autophagic vacuole (AV) compartment and its different subcompartments (early, advanced, late, and fused AVs), as well as of changes of rough-surfaced endoplasmic reticulum (RER) showed: 1. Pancreatic acinar cells react to vinblastine biphasically, i.e. two expansion phases of the AV compartment, the first in the 0 to 90 min and the second in the 2 to 8 h post-injectional periods, were detected. 2. Fusions of AVs are not inhibited by vinblastine, at least during the second expansion phase when cytoplasmic volume fraction (CVF) of fused AVs steadily increased until the 12th h. Fusion of early, advanced and late AVs or composition of fused complex vacuoles (AVc) are somehow regulated, as the proportion of the three AV stages from the CVF of AVc, was maintained constant throughout the second expansion phase. 3. Stimulation of autophagosome formation and resulting substrate overload seems to be the primary mode of action by which vinblastine causes the enormous expansion of the autolysosomal compartment. 4. Degranulation of the rough-surfaced endoplasmic reticulum (RER) membranes occurs in a biphasic fashion, similarly to the volume and surface changes of the AV compartment, thus supporting our previous hypothesis, that labilization or change of RER may have a role in the formation of autophagosomes. 5. Vinblastine-induced autophagocytosis is a selective process, as mitochondria, Golgi elements and zymogen granules are very much underrepresented, whereas RER is more than twice overrepresented in the volume of early AVs, when compared to their volume fraction in the whole cytoplasm. 6. Immunogold electron microscopy revealed the presence of ubiquitinylated proteins in advanced and late, but not in early AVs.     

Problems and prospects of redirecting Hungarian agriculture towards sustainable development

Two years after the start of changing the political system in Hungary, the discussions on the need for a transition in agriculture, and especially on the future prospects of agriculture, have still not ended. Experts, researchers and members of several interest groups related to agriculture still uphold extremely different opinions about the causes of the present crisis, and about the direction of future development. Questions concerning the present situation and the future of Hungarian agriculture can be answered only if we look at the problems from a broader perspective. First of all, the time-span of analysis should be expanded into both the past and the future. The present situation can be better understood if it is considered as a stage in a long-term development process. On the other hand, to speak about sustainability without looking into the future is meaningless. The application of a system theory can help to explain the need for the disintegration or decentralization of the structure of our agricultural system. If sustainable development is preferred, viable family farms have to play a dominant role in the new structure, even if at present there are no favourable conditions for them. Broadening the perspective of our analysis is also required to include the state and development of the national economy, the directions of expected changes of internal relations and external markets, including the time and effects of membership of the European Community, expected sociological and demographical trends in Hungarian society, the complex relationships of agriculture to regional development and to the environment as a whole, and the possible or required non-food and non-agricultural use of land and other natural resources.     

Intraoperative monitoring of the motor pathway using transtracheal stimulation of the cervical spine in dogs

Although SEP monitoring of the spinal cord has been a well established method recently, not an ultimate, perfectly developed technique for monitoring of the motor system is known so far, particularly, because of the disturbing effect of narcotic drugs and relaxants on the motor evoked potentials. In this study the upper part of the spinal cord was stimulated in 14 anesthetized and relaxed dogs with a cathode attached to the intratracheal tube and an anode fixed to the cervical spinous processes. Single and serial stimuli were applied. Recordings were obtained from the exposed right femoral nerve and quadriceps muscle. Averaging was necessary when using serial stimulations. Responses were consequent and reproducible during regular anesthesia. The origin of the different responses in the spinal cord is discussed. The method seems to be appropriate for intraoperative monitoring of the thoracolumbar spine.     

Separation of oligomers of nonylphenyl ethylene oxide [correction of nonlphenylethylene oxide] on a porous graphitized carbon column

The retention of nonylphenyl ethylene oxide oligomer surfactants was determined on a porous graphitized carbon (PGC) column using water--methanol mixtures as eluents. Linear correlations were calculated between the logarithm of the capacity factor (k') and the methanol concentration in the eluent. To test the validity of the hypothesis that in the case of homologous series of solutes the intercept and slope values are intercorrelated linear correlation was calculated between the two chromatographic parameters. To elucidate the role of the length of the polar ethylene oxide chain in the retention linear correlations were calculated between the chromatographic parameters and the number of ethylene oxide groups per molecule. Nonylphenyl ethylene oxide oligomers were well separated on the PGC column. Significant linear relationships were found between the corresponding chromatographic parameters indicating that the solutes behave as a homologous series of compounds. The retention of surfactants increased linearly with increasing number of ethylene oxide groups per molecule indicating hydrophilic interactions between the solutes and the surface of PGC support.     

Laser direct writing of tin oxide patterns

Tin oxide pattern generation by laser deposition from SnCl₄ · 5H₂O in isopropanol is reported. Smooth, even stripes of thicknesses ranging from 20 to 120 nm with sharp, well defined edges and cross-section are deposited by scanning Ar⁺ laser beam (λ = 514.5 nm) focused onto the substrate—solution interface with a constant speed of 1 mm s⁻¹. The linewidth linearly increases from 26 to 42 μm with increasing the power from 40 to 120 mW. The reproducibility of pattern generation is extremely good as revealed by SEM-EDXI and μRBS. The minimum DC resistivity of 1.7×10⁻² Ωcm, measured without any process optimization, favourably compares with those reported for films prepared by other techniques. The chemical composition of the film material is SnO_x with 1.1 < x < 1.5 as determined by an XPS-XAES study.