bluuebunny/crossref_metadata_2025_split huggingface dataset:
Correlation Dimension of the Human Sleep Electroencephalogram: Cyclic Changes in the Course of the Night
Authors: Achermann Peter , Hartmann Rolf , Gunzinger Anton , Guggenbüh Walter , Borbély Alexander A. 
Published: April 2006

AbstractThe complexity of the electroencephalogram (EEG) during human sleep can be estimated by calculating the correlation dimension. Due to the large number of calculations required by this approach, only selected short (4–164 s) segments of the sleep EEG have been analysed previously. By using a new type of personal supercomputer, we were able to calculate the correlation dimension of overlapping 1 min EEG segments for the entire sleep episode (480 min) of 11 subjects and thereby delineate the time course of the changes. The correlation dimension was high in episodes of rapid eye movement (REM) sleep, declined progressively within each non‐REM sleep episode, and reached a low level at times when EEG slow waves (0.75–4.5 Hz) were dominant. However, whereas slow‐wave activity showed its typical progressive decline from non‐REMIREM sleep cycle 1 to 4, no such trend was present for the correlation dimension. By providing an estimate of the complexity of a signal and being independent of amplitude and frequency measures, the correlation dimension represents a novel approach to exploring the dynamics of sleep and the processes underlying its regulation.
A Unique Achiasmatic Anomaly Detected in Non‐albinos with Misrouted Retinal‐fugal Projections
Authors: Apkarian Patricia , Bour Lo , Barth Peter G. 
Published: April 2006

AbstractIn mammals with binocular vision, projections of retinal sons to primary retino‐recipient nuclei establish a strict visuotopic and eye‐segregated arrangement. Normal primate visual pathway organization is characterized by orderly hemiretina separation in which nasal‐retinal axons cross at the optic chiasm and project to primary contralateral subcortical and cortical structures while temporal‐retinal fibres project ipsilaterally to corresponding visual structures. We report here, in two unrelated children, an unusual visual pathway malformation in which nasal‐retinal cortical projections, unable to decussate due to the inborn absence of an optic chiasm, erroneously route ipsilaterally to visual projection targets. We have termed this newly documented achiasmatic condition the non‐decussating retinal‐fugal fibre syndrome (Apkarian er al., Invest. Ophthalmol. Vis. Sci., 34, Suppl., 711, 1993).
Expression of GAP‐43 in the Granule Cells of Rat Hippocampus After Seizure‐induced Sprouting of Mossy Fibres: In Situ Hybridization and Immunocytochemical Studies
Authors: Bendotti Caterina , Pende Mario , Samanin Rosario 
Published: April 2006

AbstractThe axonal growth‐associated protein GAP‐43 is believed to play some role in the synaptic remodelling that takes place in the hippocampus of adult rats after certain experimental lesions. GAP‐43 mRNA is highly expressed in adult CA3 pyramidal cells but almost absent in the dentate granule cells. We analysed whether the sprouting of granule cell axons, the mossy fibres of the hippocampus, caused by kainic acid‐induced seizures in adult rats was associated with any induction of GAP‐43 mRNA in granule cells and with any changes in the immunostaining pattern of GAP‐43 in the hippocampus. Increased GAP‐43 mRNA expression was found to be induced in granule cells 18, 24 and 30 h after a systemic injection of kainic acid which induced generalized seizures in adult rats, and returned to control levels by 48 h post‐treatment. No effect was observed in other regions of the hippocampus. However, when kainic acid was injected into 15‐day‐old rats, which responded with generalized seizures but no sprouting of mossy fibres, there was no induction of GAP‐43 mRNA in the granule cells, suggesting a close relation between GAP‐43 expression and sprouting of these cells. Seven days after kainic acid injections, GAP‐43 immunostaining was decreased in the inner molecular layer of the dentate gyrus except for a thin supragranular band, whereas 30 days after treatment all animals showed increased GAP‐43 immunoreactivity in the whole inner molecular layer. Since collaterals of mossy fibres grow in the inner molecular layer after kainic acid‐induced seizures, these results support the theory that GAP‐43 plays a role in synaptic remodelling in the adult central nervous system.
Loss of the Compound Action Potential: an Electrophysiological, Biochemical and Morphological Study of Early Events in Axonal Degeneration in the C57BL/Ola Mouse
Authors: Tsao J. W. , Brown M. C. , Carden M. J. , McLean W. G. , Perry V. H. 
Published: April 2006

AbstractIn the C57BL/Ola (Ola) mouse strain there is a marked slowing of axonal disintegration during Wallerian degeneration. The locus of the mutation controlling this phenomenon (slow Wallerian degeneration‐ Wlds) has been mapped to chromosome 4, and its protective effect decreases with advancing age. Using biochemical, electrophysiological and histological techniques, the present study was undertaken to determine whether neurofilament phosphorylation and stability are altered or whether calcium‐activated proteases are absent in the sciatic nerves of Ola mice. A compound action potential was detectable only when neurofilaments were present and normal axonal architecture was seen. In 1‐month‐old Ola mice, compound action potentials and neurofilaments were still detectable at 21 days post‐transection, whereas both were undetectable by 2 days in BALB/c and C57BL/6J (6J) mice of the same age. Neurofilament levels declined faster with advancing Ola age, confirming previous results, whereas degeneration slowed in ageing BALB/c and 6J mice. In vitro and in vivo degeneration rates were comparable in BALB/c and 6J nerves. Ola nerves, however, showed more rapid decline in vitro than in vivo. Ola and BALB/c nerves frozen and then thawed and incubated in the presence of calcium ions and the ionophore A23187 were not resistant to degradation by intrinsic proteases. Even when a compound action potential could no longer be elicited, however, a majority of nerves still had >50% of myelinated and unmyelinated axons whose electron microscopic profiles appeared normal. Thus, it appears that the first event in Wallerian degeneration in the Ola mouse is a change at the plasma membrane‐a transected nerve becomes unable to conduct a compound action potential. Degeneration of the cytoskeleton is a later, separable event.
Localization of Aminopeptidase N and Dipeptidyl Peptidase IV in Pig Striatum and in Neuronal and Glial Cell Cultures
Authors: Barnes Kay , Kenny A. John , Turner Anthony J. 
Published: April 2006

AbstractThe subcellular distribution of the plasma membrane ectoenzymes, aminopeptidase N (aminopeptidase M) and dipeptidyl peptidase IV, has been examined by fractionating homogenates of porcine striata by a discontinuous Percoll gradient centrifugation procedure which distinguishes fractions containing pre‐ and post‐synaptic elements. The two enzymes showed different distributions–dipeptidyl peptidase IV did not show a significant pre‐synaptic location, whereas aminopeptidase N was present on both pre‐ and post‐synaptic fractions. Immunofluorescent staining on mixed and neuron‐enriched primary cultures of pig striatal tissue using affinity purified antibodies to the aminopeptidase and to the dipeptidyl peptidase revealed the ectoenzymes on distinct populations of cells. The astrocytic identity of the aminopeptidase N‐staining cells was established by correlation with immunostaining for glial fibrillary acidic protein and for vimentin by confocal microscopy. Ultracryosections of striatum immunostained with gold‐labelled immunoglobulins of differing diameters demonstrated aminopeptidase N on pericytes and confirmed its location on endothelial and astrocytic glial cells. Thus, several independent approaches indicated that aminopeptidase N, in addition to being present on endothelial and synaptic membranes, is found on astrocytes and pericytes in the perivascular neuropil, whereas dipeptidyl peptidase IV is less widely distributed on microvessels and appears not to have a synaptosomal location.
Creatine Kinase Isoenzymes in Chicken Cerebellum: Specific Localization of Brain‐type Creatine Kinase in Bergmann Glial Cells and Muscle‐type Creatine Kinase in Purkinje Neurons
Authors: Hemmer Wolfram , Zanolla Else , Furter‐Graves Elizabeth M. , Eppenberger Hans M. , Wallimann Theo 
Published: April 2006

AbstractCreatine kinase isoenzymes were localized in the chicken cerebellum by the use of isoenzyme‐specific anti‐chicken creatine kinase antibodies. Brain‐type creatine kinase was found in high amounts in the molecular layer, particularly in Bergmann glial cells but also in other cells of the cerebellar cortex, e.g. in astrocytes and in the glomerular structures, as well as in cells of the deeper nuclei. A mitochondrial creatine kinase isoform was primarily localized to the glomerular structures in the granule cell layer and was also identified in Purkinje neurons. Surprisingly, a small amount of the muscle‐type creatine kinase isoform was identified in cerebellar extracts by immunoprecipitation, immunoblotting and native enzyme electrophoresis, and was shown to be localized exclusively in Purkinje neurons. Cell type‐specific expression of brain‐ and muscle‐type creatine kinase in Bergmann glial cells and Purkinje neurons, respectively, may serve to adapt cellular ATP regeneration to the different energy requirements in these specialized cell types. The presence of brain‐type creatine kinase in Bergmann glial cells and astrocytes is discussed within the context of the energy requirements for ion homeostasis (K+ resorption), as well as for metabolite and neurotransmitter trafficking. In addition, the presence of muscle‐type creatine kinase in Purkinje neurons, which also express other muscle‐specific proteins, is discussed with respect to the unique calcium metabolism of these neurons and their role in cerebellar motor learning.
Brain Insults in Rats Induce Increased Expression of the BDNF Gene through Differential Use of Multiple Promoters
Authors: Kokaia Zaal , Metsis Madis , Kokaia Merab , Bengzon Johan , Elmér Eskil , Smith Maj‐Lis , Timmusk Tõnis , Siesjö Bo K. , Persson Håkan , Lindvall Olle 
Published: April 2006

AbstractThe rat brain‐derived neurotrophic factor (BDNF) gene consists of four short 5‐exons linked to separate promoters and one 3′‐exon encoding the mature BDNF protein. Using in situ hybridization we demonstrate here that kindling‐induced seizures, cerebral ischaemia and insulin‐induced hypoglycaemic coma increase BDNF mRNA levels through insult‐ and region‐specific usage of three promoters within the BDNF gene. Both brief (2 min) and longer (10 min) periods of forebrain ischaemia induced significant and major increases only of exon III mRNA in the dentate gyrus. Following hypoglycaemic coma (1 and 30 min), exon III mRNA was markedly elevated in the dentate gyrus and, in addition, exon I mRNA showed a moderate increase. Single and recurrent (n= 40) hippocampal seizures significantly increased expression of exon I, II and III mRNAs in the dentate gyrus granule cells. After recurrent seizures, including generalized convulsions, there were also major increases of both exon I and III mRNAs in the CA3 region, amygdala, piriform cortex and neocortex, whereas in the hippocampal CA1 sector marked elevations were detected only for exon III mRNA. The insults had no effect on the level of exon IV mRNA in the brain. The region‐ and insult‐specific pattern of promoter activation might be of importance for the effectiveness of protective responses as well as for the regulation of plastic changes following brain insults.
The Extracellular Matrix Molecule Janusin Regulates Neuronal Morphology in a Substrate‐ and Culture Time‐dependent Manner
Authors: Lochter André , Taylor Joanne , Fuss Babette , Schachner Melitta 
Published: April 2006

AbstractJanusin is an extracellular matrix glycoprotein with structural homology to tenascin. In search of extracellular matrix components which govern the differentiation of neurons in the central nervous system, we have investigated the influence of janusin on the differentiation of hippocampal neurons in vitro. Janusin coated onto nitrocellulose was a good substrate for attachment of cell bodies and neurite outgrowth after 21 h of culture. Most cells exhibited a polarized morphology with one long major neurite and one or two short minor neurites. When janusin was coated onto a polyornithine‐conditioned plastic surface, it increased the polarity of neurons in that the length of major neurites was increased and the length and number of minor neurites were decreased when compared with the control polyornithine‐conditioned plastic without janusin. As we have shown before for tenascin, laminin and fibronectin, polarization was preceded by an increase in the number and length of all neurites during the first hours after cell plating. This study therefore adds janusin to the increasing number of extracellular matrix glycoproteins which promote axonal but not dendritic growth.
Voltage‐dependent Kinetics of N‐Methyl‐d‐aspartate Synaptic Currents in Rat Cerebellar Granule Cells
Authors: D'Angelo Egidio , Rossi Paola , Taglietti Vanni 
Published: April 2006

AbstractDecay kinetics of N‐methyl‐d‐aspartate excitatory postsynaptic currents (NMDA‐EPSCs) have been voltage‐dependent in some, but not all neurons studied so far, and almost no information has been available on the voltage‐dependence of the rising phase. In this work we investigated the effect of membrane potential on rising and decay kinetics of the NMDA‐EPSC in cerebellar granule cells using the tight‐seal whole‐cell recording technique. NMDA‐EPSCs were evoked by electrical mossy fibre stimulation in the presence of 10 μM 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione, 1.2 mM Mg2+ and 5 μM glycine. The rate of rise of NMDA‐EPSCs remained substantially unchanged when the cell was depolarized, indicating that the limiting step of channel opening was voltage‐insensitive. The NMDA‐EPSC, however, flattened around the peak and the time‐to‐peak increased. This observation was explained by the influence of decay. Decay was biphasic and slowed down with membrane depolarization. Moreover, the fast component of decay increased less than the slow component. This complex voltage‐dependence may extend the integrative role of the NMDA current during synaptic transmission.
Up‐regulation of Neurotensin mRNA in the Rat Striatum After Acute Methamphetamine Treatment
Authors: Castel M. N. , Morino P. , Dagerlind Å. , Hökfelt T. 
Published: April 2006

AbstractThe effect of acute subcutaneous administration of methamphetamine on the expression of neurotensin mRNA was investigated in the adult rat striatum. At different time points (2, 6 and 24 h) following drug administration rats were killed, and mRNA levels were quantified both on films and emulsion‐dipped tissue sections from two striatal levels. Two hours after methamphetamine injection, a dramatic increase in neurotensin mRNA levels was detected in different areas of the striatum at both rostral and caudal levels. Numerous positive cells were observed in the dorsomedial, dorsolateral and ventrolateral parts of the striatum. This up‐regulation reflected an increase both in the number of cells expressing neurotensin mRNA and in the mean mRNA levels. This increase was still present after 6 h and was similar to the 2 h treated group at the rostral level of the striatum, but lower at the caudal one. Twenty‐four hours after methamphetamine injection, neurotensin mRNA levels were back to control values, or in some areas even below. A strong increase in neurotensin mRNA‐expressing cells was also seen in the olfactory tubercle, and the time‐course was similar to the one observed in the striatum. In a second set of experiments, the effect of methamphetamine was evaluated on adjacent striatal sections hybridized with probes directed against neurotensin and substance P mRNAs, respectively. Two hours after drug administration, a significant increase in the levels of both peptide mRNAs was observed (+ 190% for neurotensin, +80% for substance P). These results demonstrate that methamphetamine is able to induce a dramatic, rapid and transient increase in striatal neurotensin mRNA levels, which may partly account for the elevation in neurotensin peptide levels observed in the striatonigral pathway after methamphetamine. The different anatomical localization of neurotensin mRNA‐expressing cells observed after haloperidol and methamphetamine treatments, as well as the fact that the D1 receptor antagonist SCH‐23390 is able to counteract the effect of methamphetamine but not that of haloperidol on neurotensin mRNA expression, suggests that there are at least two different subpopulations of neurotensin cells in the striatum. One population is regulated via D1 receptors and projects to the substantia nigra pars reticulata. The second is sensitive to D2 receptor stimulation and may project to the globus pallidus and/or may represent interneurons.
The SP1 Antigen in Subplate Neurons of the Developing Cat Cortex is an Immunoglobulin‐like Molecule
Authors: Henschel Reinhard , Wahle Petra 
Published: April 2006

AbstractMonoclonal antibody subplate‐l (mAb SP1) specifically stains somata, dendrites and axons of spiny inverted pyramidal neurons in the subplate zone in the early postnatal kitten neocortex. The SP1 antigen has been previously identified as a cytosolic protein of apparent molecular weight 56 kDa. We have now employed immune‐affinity chromatography to further characterize this antigen. An antigen with SP1‐like immunoreactivity (ir) is present in various organs, and is particularly enriched in blood plasma. Exsanguination of the organs prior to protein extraction reduces the SP1‐ir band dramatically, indicative of a blood‐borne molecule. The 56 kDa SP1‐ir antigen was purified from plasma by affinity chromatography and subjected to Edman degradation. The first 20 N‐terminal amino acids show 80% homology to the N‐terminus of immunoglobulin heavy chain of man, the mouse and the dog. If the 56 kDa SP1‐ir antigen in plasma is an immunoglobulin, and if an immunoglobulin‐like molecule is present in the subplate, then antisera against cat immunoglobulins should stain subplate neurons. A polyclonal antiserum against cat IgG intensely stains the somata and dendrites of subplate neurons. On protein blots, this antiserum recognizes the 56 kDa band, and an additional band of ∼27 kDa, corresponding in size to immunoglobulin light chains. Preabsorbing mAb SP1 with cat immunoglobulin G abolishes the immunoreactivity in sections of kitten cortex. Further, it dramatically reduces the reactivity on protein blots. The results suggest that the 56 kDa SP1‐ir antigen in cortical subplate neurons belongs to the immunoglobulin superfamily.
Pharmacology and Biophysical Properties of α7 and α7 ‐ α8 α‐Bungarotoxin Receptor Subtypes Immunopurified from the Chick Optic Lobe
Authors: Gotti C. , Hanke W. , Maury K. , Moretti M. , Ballivet M. , Clementi F. , Bertrand D. 
Published: April 2006

AbstractTwo chick optic lobe α‐bungarotoxin receptor subtypes (α7 and α7 ‐ α8) were immunopurified using polyclonal antibodies raised against synthetic peptides of chick α7 and α8 α‐bungarotoxin receptor subunits. The α7 subtype contained the Mr 57 000 α7 subunit, and represented 60 ‐ 70% of the α‐bungarotoxin receptors; the α7‐α8 subtype contained the Mr 57 000 α7 and α8 subunits, and represented only 20 ‐ 25% of the receptors. Both subtypes also had an additional Mr 52 000 subunit. The affinity of these subtypes for α‐bungarotoxin as well as antagonists was similar. However, the α7 ‐ α8 subtype displayed consistently higher affinities for agonists. When reconstituted in planar lipid bilayers, the α7 ‐ α8 subtype displayed several conductance states of 10 ‐ 50 pS; the α7 subtype had only one conductance state of 45 pS. The α7 ‐α8 subtype was activated by lower agonist concentrations than the α7 subtype. When expressed in Xenopus oocytes, the α8 subunit formed functional homomeric receptors that desensitized rapidly. These channels were blocked by α‐bungarotoxin and displayed a higher affinity for agonists than the α7 homomeric receptor. Taken together, these data indicate that at least two α‐bungarotoxin subtypes are present in the chick optic lobe. They operate as ligand‐gated channels and display different agonist sensitivities and kinetics/conductance properties.
Eye Saccade Dynamics During Paradoxical Sleep in the Cat
Authors: Vanni‐Mercier G. , Pelisson D. , Goffart L. , Sakai K. , Jouvet M. 
Published: April 2006

AbstractCat eye movements were recorded during wakefulness and paradoxical sleep with the technique of the scleral search coil in a magnetic field. During waking, eye movements consisted of a succession of saccades and fixation phases. During paradoxical sleep, the pattern of eye movements displayed drifts of variable velocity and direction and short fixation phases, upon which saccades superimposed. These saccades displayed a repetitive, stereotyped, asymmetrical pattern. The maximum velocity/amplitude relationships, i.e. the main sequences, were determined for spontaneous and visually induced saccades of waking and for the following types of saccades during paradoxical sleep: (i) isolated saccades accompanied by ponto‐geniculo‐occipital (PGO) waves, (ii) isolated saccades accompanied by eye movement potentials (EMP), and (iii) saccades in bursts accompanied by PGO waves. The slope of the main sequence relationship of any type of paradoxical sleep saccade (from 21.7°/° for isolated saccades to 35.6°/s° for saccades in bursts) was higher than that of any type of waking saccade (11.2°/s° for spontaneous saccades to 14.7°/s° for visually elicited ones). Furthermore, during paradoxical sleep, saccades in bursts were faster than isolated ones. This demonstrates that different neurophysiological mechanisms subserve the generation of waking saccades, paradoxical sleep isolated saccades and paradoxical sleep saccades in bursts, or that the oculomotor system is in a different state of excitation during these different sets of saccades. These findings throw new light on the functioning of the oculomotor system during paradoxical sleep and are discussed in terms of the functional significance of paradoxical sleep saccades and PGO waves.