bluuebunny/crossref_metadata_2025_split huggingface dataset:
A crossed corticotectal projection from the lateral suprasylvian area in the cat
Authors: Baleydier Christine , Kahungu Mbwiti , Mauguiere François 
Published: December 2004

AbstractCrossed cortical projections to the superior colliculus of the cat were demonstrated by unilateral superior colliculus injections of horseradish per‐oxidase (HRP) and by cortical injections of radioactive amino acids.This crossed corticotectal projection originates in the lateral bank of the middle suprasylvian sulcus and in both banks of the posterior suprasylvian sulcus. The site of termination of the contralateral corticotectal projection is restricted to the anterior margin of the superior colliculus (SC) while the ipsilateral projection spreads over the whole SC. The contralateral terminal areas are restricted to the superficial tectal layers. The projection fibers reach the contralateral superior colliculus by crossing the collicular commissure.The existence of such a connection may help to explain certain elec‐trophysiological observations.
Dual olfactory representation in the rat thalamus: An anatomical and electrophysiological study
Authors: Price Joseph L. , Slotnick Burton M. 
Published: December 2004

AbstractA combination of electrophysiological and anatomical techniques was used to determine the sites of termination of olfactory projections to the thalamus and the distribution of the cells of origin of these projections within the olfactory cortex. Following electrical stimulation of the olfactory bulb, short‐latency unit responses were recorded not only in the central segment of the mediodorsal thalamic nucleus but also in the ventral and anterior parts of the submedial thalamic nucleus. Responses were not obtained in the ventral or lateral parts of the mediodorsal nucleus, in the dorsal part of the submedial nucleus, or in the intralaminar nuclei between the mediodorsal and submedial nuclei.The cells of origin of the projection were identified by making injections of horseradish peroxidase conjugated to wheat germ agglutinin (HRP*WGA) into the thalamus and examining the olfactory cortex for retrogradely labeled cells. Following injections into the mediodorsal nucleus, labeled cells were found in the polymorphic cell zone deep to the olfactory tubercle, in the ventral endopiriform nucleus deep to the piriform cortex, and in an equivalent position deep to the periamygdaloid and lateral entorhinal cortices. After injections into the submedial nucleus, a smaller number of labeled cells were found in similar locations, except that they were restricted to the rostral olfactory cortical areas and were not found deep to the lateral part of the piriform cortex. Retrogradely labeled cells and anterogradely labeled axons were also found in the lateral orbital and ventral agranular insular areas of the prefrontal cortex with injections into the mediodorsal nucleus, and in the ventrolateral orbital area with injections into the sub‐medial nucleus.Anterograde tracing experiments, using the autoradiographic method, have confirmed these results. Injections of 3H‐leucine deep to the junction between the anterior piriform cortex and the olfactory tubercle label axons in both the central segment of the mediodorsal nucleus and the ventral part of the submedial nucleus, while injections deep to the posterior piriform cortex label axons in the mediodorsal nucleus only. Within the mediodorsal nucleus, the projection also appears to be organized so that fibers which arise more rostrally terminate ventrolaterally in the central segment, while fibers which arise more caudally terminate more dorsomedially.These results indicate that there is a substantial and possibly dual thalamocortical mechanism available for processing of olfactory stimuli.
Morphology and location of tectal projection neurons in frogs: A study with hrp and cobalt‐filling
Authors: Lázár Gy. , Tóth P. , Csank Gy. , Kicliter E. 
Published: December 2004

AbstractTectal projection neurons were labeled by retrograde transport of horseradish peroxidase (HRP) or cobaltic‐lysine. The tracer substances were delivered iontophoretically or by pressure injection or diffusion into various regions of the brain or spinal cord. Histochemical procedures allowed identification of labeled cells projecting to the injected regions. Many neurons were filled with cobaltic‐lysine, resulting in a Golgi‐like staining.After cobalt injections in the diencephalon most of the labeled cells, identified as small piriform neurons, were located in layer 8 of the tectum. Two types of small piriform neurons were distinguished. Type 1 neurons have flat dendritic arborizations confined to lamina D, while the dendrites of type 2 cells may span all of the superficial tectal strata. In smaller numbers large piriform, pyramidal, and ganglionic cells of the periventricular tectal layers were labeled after diencephalic injections.Rhombencephalic cobalt and HRP injections labeled cells whose axons form the tectobulbospinal tract. The neurons most frequently labeled were large ganglionic cells. Ipsilaterally, the majority of their somata were located in layer 7, and their dendrites arborized mainly in lamina F. Con‐tralaterally, labeled ganglionic cell somata occupied the top of layer 6, and most of their dendritic end‐branches entered lamina B. The possible functional significance of this anatomical arrangement is discussed.After tectal cobalt injections the topography of the tectoisthmic projection and the terminals of tectal efferent fibers in the diencephalon and brainstem were observed. It is concluded that the organization of frog tec‐tofugal pathways is very similar to that of mammals.
An examination of intraspinal sprouting in dorsal root axons with the tracer horseradish peroxidase
Authors: Rodin Barbarae , Sampogna Sharon L. , Kruger La Wrence 
Published: December 2004

AbstractPostdeafferentation reorganization in the central terminal fields of spared dorsal root axons was evaluated by examining the intraspinal distribution of horseradish peroxidase‐labeled sciatic nerve afferent fibers at various intervals following the removal of several lumbar dorsal root ganglia. The sciatic projection to the spinal cord, as determined by the pattern and density of intraspinal reaction product, was remarkably stable following the ganglionectomies. For as long as 3 months later, there was no evidence that sciatic afferent fibers had formed anomalous connections either with new spinal segments or in denervated areas within normal segments of entry. These findings cast doubt upon the existence of anatomic reorganization within the spinal cord following its partial deafferentation and suggest that physiological processes other than new axonal growth underlie observations such as postdenervation alterations in the response properties of dorsal horn neurons and the recovery of behavioral function.
Sex differences in the pattern of steroidaccumulation by motoneurons of the rat lumbar spinal cord
Authors: Breedlove S. Marc , Arnold Arthur P. 
Published: December 2004

AbstractWe previously reported that male rat lumbar motoneurons accumulate radioactivity after injection of tritiated testosterone (T) or dihydrotestoster‐one (DHT), but not estradiol (E). We now report autoradiographic evidence that lumbar motoneurons in male rats accumulate T or its metabolites more frequently than do female motoneurons. However, this sex difference in hormone accumulation by motoneurons is not observed following the injection of DHT or E, both of which are normal metabolites of T. Very few motoneurons from any population accumulated E or its metabolites. In fact, some motoneurons had fewer silver grains over their nuclei than would be expected by chance, thus suggesting that these cells not only failed to accumulate E or its metabolites, but actively or passively excluded them from their nuclei. Virtually every motoneuron of either sex accumulated hormone after DHT injection. Following T injection, more motoneurons were labeled in males (72–77%) than in females (28ndash39%), indicating a sex difference in hormone accumulation. Taken together, these results suggest that either (1) there are separate receptors for T and DHT, and motoneurons have more T receptors (but equal numbers of DHT receptors) in males than in females, or (2) the motoneurons of male rats have greater access to systemically administered T or its metabolites than do those of females.
The cerebellopontine system in the rat. I. Autoradiographic studies
Authors: Watt Carl B. , Mihailoff Gregory A. 
Published: December 2004

AbstractThis study utilized light microscopic autoradiographic procedures to describe the projections from the three major subdivisions of the deep cere‐ bellar nuclei (DCN) to the basilar pontine nuclei (BPN). Although the vast majority of cerebellopontine axons reached the BPN via the descending limb of the brachium conjunctivum (BC) after crossing the midline within the midbrain, a relatively small number of ipsilaterally projecting fibers was also observed. Fascicles of cerebellopontine axons left the main bundle of de‐scending limb fibers throughout much of the rostrocaudal length of the BPN and passed around and through the medial lemniscus and cerebral peduncle to enter the pontine gray. The lateral cerebellar nucleus gave rise to the largest number of cerebellopontine fibers, whose terminal fields exhibited both diffuse and patchlike labeling patterns within each of the major subdi‐ visions of the BPN including medial, ventral, lateral, and dorsal areas. Pro‐ jections from the interpositus complex exclusive of its posterior division were fewer and less widely distributed than those from the lateral nucleus. Interpositopontine fibers terminated primarily in the caudal one‐half of the BPN in medial, ventral, and lateral regions and overlapped somewhat with projections from the lateral cerebellar nucleus. Pontine projections ema‐ nating from the medial cerebellar nucleus were the fewest and most re‐ stricted in distribution relative to the other two cerebellar efferent systems. Such fibers formed a patchlike network of terminal fields which extended throughout much of the rostrocaudal length of the BPN in medial and dorso‐ medial regions. A relatively small but considerable number of ipsilateral cer‐ ebellopontine fibers terminated in pontine regions, which often mirrored the typical contralateral projection fields. Although it proved difficult to deter‐ mine the precise origin of the ipsilateral fiber systems, it appeared that each of the three major DCN subdivisions made some contribution. Also it was apparent that considerable overlap existed between cerebellopontine projec‐ tion zones and those of other pontine afferents including sensorimotor, vi‐ sual, and auditory cortices, the superior colliculus, and the mammillary nu‐ clei of the hypothalamus. Moreover, cerebellopontine terminal fields were congruent in some instances with discrete clusters of BPN neurons which serve as the source of pontocerebellar fiber systems, reaching portions of the lateral cerebellar hemispheres, posterior vermis, and the paraflocculus.
Single‐channel characteristics of the large‐conductance anion channel in rat cortical astrocytes in primary culture
Authors: Jalonen Tuula 
Published: December 2004

AbstractCultured rat cortical astrocytes, in addition to a variety of voltage‐sensitive potassium channels, also express anion channels. However, the behavior and regulation of these anion channels have been far less studied. This paper describes a patch‐clamp study on a voltage‐sensitive 200–300 pS high‐conductance single‐channel anion current, which seems to possess at least five different open sublevels or, alternatively, be formed froin five or more small‐conductance ion channels linked together. This channel is voltage dependent, showing a bell‐shaped open probability curve with highest open probability close to the reversal potential (zero‐current). Although potassium channels are commonly detected in astrocytes in cell‐attached and excised patches with both normal osmolarity and hypoosmotic solutions, the occurrence of the anion channel is clearly increased in isolated patches when hypoosmotic bath solutions are used. Also, cell aging in culture and the preparation of secondary cell cultures by trypsinization seem to increase the rate of occurrence of the anion channel. Though this channel is more routinely seen when a membrane patch is excised from the cell, occasionally cell‐attached configurations with instant channel activity can be formed. While the modulation of this anion channel was being studied, it was found to be blocked by an anion transport inhibitor, L‐644,711, reported to affect cell volume regulation in astrocytes. © 1993 Wiley‐Liss, Inc.
Growth and degeneration of axons on astrocyte surfaces: Effects on extracellular matrix and on later axonal growth
Authors: Ard March D. , Schachner Melitta , Rapp Jeffrey T. , Faissner Andreas 
Published: December 2004

AbstractCultured astrocytes deposit an extracellular matrix which has been shown by immunocytochemistry to react with antibodies to tenascin, laminin, and fibronectin. Neuronal‐glial interaction down‐regulates these components of the matrix, causing a reduction in extracellular matrix localized to areas of contact with axons. Axons used for these experiments were from embryonic rat retinal explants.In some experiments explants were removed from the co‐cultures and their axons allowed to degenerate. Degeneration of axons did not reverse the local reduction of extracellular matrix brought about by axon outgrowth. The period of axon outgrowth studied was 4‐5 days; the period of degeneration was 2‐3 days.Astrocytes alone, astrocytes with intact retinal explants, and astrocytes with 2‐day degenerated retinal axons were tested for their ability to support neurite outgrowth from embryonic rat cortical neurons. Neurite outgrowth occurred on all astrocyte cultures. Cortical neurite lengths, measured 2 days after plating, were not significantly different between astrocytes alone and astrocytes with degenerated retinal axons. However, there was a tendency for neurites to be shorter on astrocytes with intact retinal axons present.Two conclusions may be drawn from these results. First, the state of differentiation of astrocytes, as marked by their assembly of extracellular matrix, is altered by contact with axons. Second, degeneration of axons alone, in the absence of other cell types, is not a sufficient signal to reestablish assembly of extracellular matrix. However, neither is it a sufficient signal to render astrocytes inhospitable to further axonal outgrowth or regeneration. © 1993 Wiley‐Liss, Inc.
Calcium‐mobilizing and electrophysiological effects of bradykinin on cortical astrocyte subtypes in culture
Authors: Stephens Gary J. , Cholewinski Andrez J. , Wilkin Graham P. , Djamgoz Mustafa B. A. 
Published: December 2004

AbstractThe possible consequences of activating bradykinin (Bk) receptors on identified astrocyte subtypes derived from rat cortex have been investigated in terms of: 1) mobilization of intracellular Ca2+; and (2) electrophysiological response. Bk induced a rapid, transient rise in intracellular Ca2+ in 63% of cortical type‐1‐like astrocytes and 44% of type‐2 astrocytes tested. Experiments involving Ca2+‐free conditions suggested that the release occurred largely from internal stores in both astrocyte subtypes. Bk receptor activation resulted in an inward current in approximately 10% of each astrocyte subtype tested using the whole‐cell patch clamp technique. The use of perforated patch recording confirmed a similar population of cells responsive to Bk. The Bk‐induced current was associated with a decrease in membrane conductance. The reversal potential was close to the K+equilibrium potential, consistent with the closure of K+ channels. The current demonstrated similar EC50values and Hill coefficients and also a marked degree of desensitization for both astrocyte subtypes. Recordings from type‐1‐like astrocytes indicated that the receptor mediating the electrophysiological response was of the B2 subtype. The data were consistent with the functional translation of Bk receptor occupation to physiological responses in distinct sub‐populations of cortical type‐1‐like and type‐2 astrocytes. © 1993 Wiley‐Liss, Inc.
Pathophysiology of glial growth factor receptors
Authors: Raivich Gennadij , Kreutzberg Georg W. 
Published: December 2004

AbstractActivation and proliferation of glial cells are common events in the pathology of the nervous system. Although we are only beginning to understand the molecular signals leading to glial activation in vivo, there is increasing evidence that growth factors and their receptors may play an important part. In this paper we summarize the data on the pathophysiology of glial growth factor receptors and their ligands in the central and peripheral nervous systems. © 1994 Wiley‐Liss, Inc.
Receptor‐mediated regulation of neuropeptide gene expression in astrocytes
Authors: Schwartz Joan P. , Nishiyama Nobuyoshi , Wilson Delores , Taniwaki Takayuki 
Published: December 2004

AbstractOne of the functions of glial receptors is to regulate synthesis and release of a variety of neuropeptides and growth factor peptides, which in turn act on neurons or other glia. Because of the potential importance of these interactions in injured brain, we have examined the role of two different receptors in the regulation of astrocyte neuropeptide synthesis. Stimulation of β‐adrenergic receptors on type 1 astrocytes resulted in increased mRNA and protein for the proenkephalin (PE) and somatostatin genes. This receptor also increased expression of nerve growth factor (NGF) and brain‐derived neurotrophic factor (BDNF). The potential role of opiate receptors was examined in several ways. Treatment of newborn rats for 7 days with the opiate antagonist naltrex‐one, prior to preparation of astrocytes, had no effect on PE mRNA or met‐enkephalin content but resulted in a significant increase in NGF content. However, treatment of astrocytes in culture with met‐enkephalin, morphine, or naltrexone had no effect on any of these parameters. No opiate binding could be detected, using either etorphine or bremazocine, to membranes of astrocytes prepared from cortex, cerebellum, striatum, or hippocampus of 1‐day, 7‐day, or 14‐day postnatal rats. Thus we conclude that type 1 astrocytes do not express opiate receptors and that the in vivo effects of naltrexone are mediated indirectly via some other cell type/receptor. © 1994 Wiley‐Liss, Inc.
Glial receptors and their intervention in astrocyto–astrocytic and astrocyto–neuronal interactions
Authors: Glowinski J. , Marin P. , Tence M. , Stella N. , Giaume C. , Premont J. 
Published: December 2004

AbstractAs shown on cultured astrocytes from the mouse, in the presence of adenosine deaminase, 2‐chloroadenosine by acting on A1‐adenosine receptors potentiated the activation of phospholipase C induced by the α1‐adrenergic agonist, methoxamine. This potentiation required the presence of external calcium and was blocked by pertussis toxin. Moreover, this potentiation resulted from a cascade of events: activation (by calcium and protein kinase C) of a phospholipase A2 coupled to A1‐adenosine receptors, release of arachidonic acid, which inhibited the reuptake of glutamate into astrocytes and finally additional activation of phospholipase C by externally accumulated glutamate through metabotropic receptors. The effects of2‐chloroadenosine and methoxamine were respectively mimicked by somatostatin and substance P while endothelins reproduced the combined effects of 2‐chloroadenosine and methoxamine. Conditioned media from treated astrocytes enriched in glutamate stimulated phospholipase C in cultured striatal neurones. In addition, glutamate alone was also found to stimulate phospholipase A2 in astrocytes through receptors exhibiting a pharmacological profile distinct from metabotropic receptors coupled to phospholipase C and the glutamate response was potentiated by ATP. Moreover, the neuronal arachidonic acid production evoked by glutamate was potentiated by acetylcholine. Finally, the combined application of 2‐chloroadenosine and methoxamine on striatal astrocytes reduced the permeability of gap junctions between astrocytes and this response was mimicked by arachidonic acid. Together, these results emphasized the contribution of astrocytes in the regulation of glutamatergic transmission. © 1994 Wiley‐Liss, Inc.
Komplexone VI. Neue einfache Titriermethoden zur Bestimmung der Wasserhärte
Authors: Schwarzenbach G. , Biedermann W. , Bangerter F. 
Published: December 2004

AbstractEs werden vier neue Methoden zur bestimmung der Wasser‐härte beschrieben. Besonders empfehlenswert sind die Methoden A und C, von denen die eine die Kalkhärte und die andere die Gesamthärte liefert. Diese beiden Methoden sind einfacher als diejenigen von Wartha‐Pfeifer und Blacher, liefern genauere Resultate und beanspruchen für die Durchführung weniger Zeig. Die Methode B ist etwas weniger genau und nur anwendbar, wenn kein Magnesiumion vorliegt. Für die vierte Methode D, die ebenfalls gute Resultate liefert, ist das notwendige Komplexon im Handel nicht erhältlich.
Untersuchungen über die Gewebsatmung. 2. Beziehungen der Aminosäurekatalyse zur Fumarsäurekatalyse bzw. zum Citronensäurecyclus
Authors: Wiss O. 
Published: December 2004

Abstract1. Fumarsäure, Bernsteinsäure, Apfelsäure, Oxalessigsäure, Ketoglutarsäure und Citronensäure Können als Kräftige Aktivatoren den oxydativen Abbau von Brenztraubensäure, Milchsäure und Glycero‐phosphorsäure durch zellfreien Rattenleberextrakt katalysieren.
Pyrazines. 3e Communication. Synthèse de 5H‐cyclopenta[b]pyrazines alkylées
Authors: Flament Ivon , Sonnay Philippe , Willhalm Bruno , Ohloff Günther 
Published: December 2004

Synthesis of alkyl‐5H‐cyclopenta[b]pyrazines.Alkyl‐5H‐cyclopenta[b]‐pyrazines (sometimes together with 5‐alkylidene‐5H‐6,7‐dihydrocyclopenta[b]pyrazines) are prepared by thermal degradation of 5‐acetoxy‐5H‐6,7‐dihydrocyclopenta[b]pyrazines; these are obtained by treatment of alkyl‐5H‐6,7‐dihydrocyclopenta[b]pyrazine N‐oxides with acetic anhydride. Cyclopenta[b]pyrazines which are potentially present in roasted food flavors possess interesting organoleptic properties.
Synthèse par cyclisation nucléophile de dérivés de sucres portant un hétérocycle inséré en spiro. Note de Laboratoire
Authors: Tronchet Jean M. J. , Gentile Bernard 
Published: December 2004

Synthesis of Sugar Derivatives Bearing a Spiro Heterocycle via Nucleophilic CyclizationTreated with the 1,4‐binucleophiles 1,2‐diaminoethane, 2‐aminoethanol, 2‐aminoethanethiol, L‐cysteine, o‐phenylenediamine, o‐aminophenol or o‐aminothiophenol the ketosugar derivative 1 gave in good yields the corresponding spiro derivatives 2–8. In each case, the reaction was stereospecific leading to the isomer bearing the N‐atom on the endo face of the bicyclic starting material. Starting from the sugar enone 9, the aromatic 1,4‐binucleophiles led stereospecifically to the spirobenzo [b]‐diazepine 10, ‐oxazepine 11 or ‐thiazepine 12. In one case, an imine (13) was isolated. As 13 cyclized to 6, the intermediate formation of these kind of derivatives could be considered as a common step for all these reactions.
Photochemistry of α,β‐Unsaturated γ,δ‐Epoxyesters. III. Experiments on Triplet Reactivity
Authors: Murato Kazuo , Frei Bruno , Schweizer Wolfhard Bernd , Wolf Hans Richard , Jeger Oskar 
Published: December 2004

AbstractOn triplet sensitization (E)‐5 gives (Z)‐5 and isomerizes via C(δ), O‐bond cleavage to the cyclobutanone 6 and the conjugated γ‐ketoester 7. ‐ On singulet excitation 6 undergoes decarbonylation and yields the bicyclo [4.1.0]heptane 8. However, on triplet sensitization 6 is converted to the isomeric tricyclononane 9 by a stereospecific oxa‐di‐π‐methane rearrangement. The structure of 9 is determined by X‐ray analysis of the p‐nitrobenzoate 15: a = 10.573, b = 14.707, c = 13.494 Å, β = 112.40°, P21/n, Z, = 4.