bluuebunny/crossref_metadata_2025 huggingface dataset:
The ascending input to the midbrain periaqueductal gray of the primate
Authors: Mantyh Patrick W.
Published: December 2004

To obtain a comprehensive map of the brainstem and spinal cord areas that project to the mesencephalic central gray small injections of hors‐radish peroxidase were made into various regions of the periaqueductal gray in a series of monkeys.

Despite the fact that different regions of the central gray were injected in separate animals, the majority of the brainstem areas containing retrogradely filled neurons remained the same. Labeled neurons were observed in the superior colliculus, periaqueductal gray, lateral parabrachial, locus coeruleus, nucleus raphe magnus and pallidus, and a variety of brainstem reticular nuclei.

In contrast to labeled brainstem areas, where labeled neurons were present predominantly ipsilateral to the injection site, the spinal trigeminal nucleus pars caudalis and the spinal cord displayed labeled cells chiefly on the side contralateral to the injection. Also in contrast to the labeled brainstem sites, where medial and lateral injection sites produced a similar pattern of labeling, medial injections in the PAG labeled almost exclusively neurons in the deep laminae (V‐X) in the spinal trigeminal nucleus pars caudalis and spinal cord while more lateral injections labeled neurons in both the deep (V‐X) and superficial (I) laminae. No consistent differences were noted in the location of labeled neurons in either brainstem or spinal sites after dorsal vs. ventral injections or caudal vs. rostral injection sites.

The present study has demonstrated that the central gray receives afferent projections from a number of brainstem and spinal areas which are known to be involved in the modulation andor conduction of nociception, while other inputs are probably involved in the regulation of visceral functions. These data support the hypothesis that the mesencephalic periaqueductal gray functions as a visceral, nociceptive, and cognitive integrator.
A light and electron microscopic study of regrowing pyramidal tract fibers
Authors: Kalil Katherine , Reh Thomas
Published: December 2004

Autoradiographic and EM techniques were used to study the regenerative capacity of severed axons in the mammalian CNS. In infant and adult hamsters the pyramidal tract was severed unilaterally in the medulla several millimeters rostral to the decussation. After, survival to adulthood, the animals received injections of [3H] Proline in the sensorimotor cortex ipsilateral to the lesion. Autoradiography showed that labeled pyramidal tract axons in the medulla did not cross the lesion site. Instead, in animals with infant lesions there was massive new axonal growth arising from the severed pyramidal tract several millimeters rostral to the cut. Most of these labeled fibers crossed to the contralateral brainstem, coalesced into a compact bundle, descended just medial to the spinal trigeminal nucleus, and grew caudally for 6–7 mm. Although the trajectory of the regrowing axons was completely abnormal, their pattern of termination in the dorsal column nuclei and dorsal horn of the cervical spinal cord was normal. Synapse formation by the anomalous regrowing pyramidal tract axons in their appropriate terminal areas was confirmed by electron microscopy of terminal degeneration in animals with infant pyramidotomies followed by adult cortical lesions. Autoradiographic labeling of the new pathway at short post‐lesion survival timers showed that the fibers grew out rapidly at about 1 mm/day, a rate somewhat slower than normal (2–4 mm/day).

There was a dramatic difference in the capacity of the pyramidal axons to regrow in animals operated as infants vs. those operated as adults. The regrowth was maximal in animals with lesions at 4–8 days of age. Capacity for new growth declined sharply thereafter such that after 20 days of age, pyramidal tract lesions elicited no new growth but instead a progressive axon degeneration retrograde to the lesion.

These results, in contrast to many previous findings, show that significant regrowth of severed axons can occur in the neonatal CNS. Most importantly pyramidal tract fibers regrowing by anomalous routes can nevertheless establish synaptic connections in appropriate terminal areas and thus, as we show in the following paper, play a functional role in maintaining normal motor behavior.
Afferent and efferent connections of the striate and extrastriate visual cortex of the normal and reeler mouse
Authors: Simmons Peter A. , Lemmon Vance , Pearlman Alan L.
Published: December 2004

In order to analyze the role of lamination in establishing the precisely ordered connectional pattern of the neocortex, we compared the afferent and efferent connections of the visual cortical areas in normal mice with those of the mutant mouse reeler (rl). The reeler mutation causes disruption of the laminar organization of the neocortex; all classes of neurons are present but are abnormally located. The corticocortical and thalamocortical connections of visual cortical areas 17, 18a, and 18b were determined in normal and reeler mice with injections of horseradish peroxidase (HRP) or HRP conjugated with wheat germ agglutinin (HRP‐WGA). The diffusion of HRP‐WGA is highly restricted due to the surface binding properties of the lectin; it was particularly effective in demonstrating retinotopically ordered connections.

We found that the patterns of connections made by the reeler mutant are indistinguishable from normal. Cortical loci in area 17 are reciprocally connected to homotopic locations in areas 18a and 18b. Area 17 is also reciprocally connected with the dorsal lateral geniculate nucleus of the thalamus and projects to the superior colliculus. Areas 18a and 18b are reciprocally connected with each other and with the lateral posterior and lateral nuclei of the thalamus, respectively. In addition, we found evidence of reciprocal connections between the lateral posterior nucleus and area 17, and between the lateral nucleus and areas 17 and 18a.

The results indicate that neurons in visual cortical areas of the reeler mutant mouse are capable of forming retinotopically organized corticocortical and thalamocortical connections in a pattern similar to that found in normal animals. Thus the genetic anomaly producing incorrect neuronal positioning during development of the reeler cortex does not seriously impede the pathway and target recognition mechanisms responsible for formation of functionally appropriate cortical connections.
The luteinizing hormone‐releasing hormone pathways in rhesus (Macaca mulatta) and pigtailed (Macaca nemestrina) monkeys: New observations on thick, unembedded sections
Authors: Silverman A. J. , Antunes J. L. , Abrams G. M. , Nilaver G. , Thau R. , Robinson J. A. , Ferin M. , Krey L. C.
Published: December 2004

Immunocytochemical procedures on thick, unembedded tissue sections were used to study the localization of LHRH neurons and fibers in the diencephalon and mesencephalon of rhesus and pigtailed macaques. Cell bodies were visualized in large numbers. Much of their dendritic arborization was also filled with reaction product. Cell bodies were present in the preoptic area, the periventricular hypothalamic zone from the level of the anterior hypothalamus to the premammillary nuclei, the infundibular nucleus, supraoptic nucleus, several septal nuclei, the nervus terminalis, and the amygdala. The localization of LHRH cells in several of these areas represents new observations. LHRH axons were observed to innervate the portal vessels in the median eminence, the organum vasculosum of the lamina terminalis, the medial mammillary nuclei, the epithalamus, and the amygdala. These observations are discussed in relationship to the regulation of gonadotropin secretion in the primate.
Insula of the old world monkey. II: Afferent cortical input and comments on the claustrum
Authors: Mufson Elliott J. , Mesulam M.‐Marsel
Published: December 2004

The afferent connections of the insula in the rhesus monkey were studied with axonal transport methods. Injections of horseradish peroxidase (HRP) in the insula revealed labeled neurons in the prefrontal cortex, the lateral orbital region, the frontopariefal operculum, the cingulate gyrus and adjacent medial cortex, the prepiriforrn olfactory cortex, the temporal pole, the cortex of the superior temporal sulcus, the rhinal cortex, the supratem‐poral plane, and the posterior parietal lobe.

Tritiated amino acid (TAA) injections in some of the cortical regions which contained retrogradely labeled neurons confirmed projections to the insula from prefrontal granular cortex, orbital frontal cortex, prepiriform cortex, temporal pole, rhinal cortex, cingulate gyrus, frontal operculum, and parietal cortex.

In these studies, cortical areas that projected to the insula also projected to the claustrum. However, the topographic and quantitative relationships between the projections into the insula and those into the claustrum were inconsistent. Moreover, the claustrum has additional connections which it does not share with the insula. A selected review of the literature suggests that the claustrum and insula differ widely also with respect to ontogenesis and functional specialization.
Stability of neuron number in cortical barrels of aging mice
Authors: Curcio C. A. , Coleman P. D.
Published: December 2004

The question of whether age‐related neuron loss occurs in the cerebral cortex of rodents, as it apparently does in humans, has not been directly answered by previous studies. The barrel, a discrete morphological and functional unit in rodent somatosensory cortex, is a favorable system in which to address the problem of neuron loss during senescence. The numerical density and absolute number of neurons as well as barrel volume were determined from a computer‐assisted three‐dimensional reconstruction of thick (100 μm) and semithin (1 μm) sections through a single barrel, C3, from inbred mice (C57Bl/6NNia) at 4, 12, 22, 26, 30, and 33 months of age.

The number and density of neuron and glial cells and the volume of the barrel did not change significantly with age. These data indicate that neuron loss is not a universal phenomenon in senescence and that there may be significant species differences in the aging of laboratory rodents and humans.
The cell masses in the brainstem of the South African clawed frog Xenopus laevis: A topographical and topological analysis
Authors: Nikundiwe Alfeo M. , Nieuwenhuys Rudolf
Published: December 2004

The ventricular sulcal pattern and the cytoarchitecture of the brainstem of Xenopus laevis, a pipid frog which retains a lateral line system throughout life, were studied in transverse Nissl‐ and Klüver‐Barrera‐stained serial sections. Four distinct longitudinal sulci, the sulcus medianus inferior, the sulcus intermedius ventralis, the sulcus limitans, and the sulcus medianus superior, could be distinguished. With the aid of the usual cytoarchitectonic criteria 42 cell groups were delineated; seven of these are primary efferent or motor nuclei, 13 are primary efferent or sensory centers, seven nuclei are considered to be components of the reticular formation, and the remaining 15 cell masses can be indicated as “relay” nuclei. In order to provide a basis for experimental work, the topographical position of the nuclei is illustrated in photomicrographs of representative levels and in graphical reconstructions.

The distribution of the cell masses and their relations to the ventricular sulci were studied with the aid of the reconstruction procedure termed topological analysis (cf. Nieuwenhuys, '74; Fig. 19). This analysis yielded the following results. The sulcus limitans extends throughout almost the entire brainstem, dividing this part of the brain into a motor basal plate and a sensory alar plate. The cell masses in the rhombencephalic basal plate fit into two longitudinal zones, a medial area ventralis and a lateral area intermedioventralis. The former contains somatomotor centers of primary and higher order, whereas the latter is composed of three primary visceromotor nuclei and one visceromotor coordinating center. The rhombencephalic alar plate is occupied by viscerosensory, general somatosensory, and special somatosensory cell masses. Two centers, the nucleus fasciculi solitarii and the nucleus visceralis secundarius, represent together a discontinuous viscerosensory zone, which is situated immediately dorsal to the sulcus limitans. The general somatosensory nuclei, i.e., the gracile and cuneate nuclei, the nucleus tractus descendens of V, and the nucleus princeps of V constitute a zone which largely overlaps the viscerosensory zone. The special somatosensory area, i.e., the area of termination of (1) primary vestibular, (2) primary acoustic, and (3) lateral line nerve fibers, is strongly developed and occupies a considerable part of the alar plate. Presumably, the fibers of each of the three categories mentioned terminate in three separate zones of gray. The midbrain can also be subdivided bilaterally into a basal plate and an alar plate. The former occupies the medial part of the tegmentum mesencephali and may be considered as the rostral extreme of the somatomotor zone. The latter comprises the lateral tegmentum and the tectum, areas which are chiefly occupied by special somatosensory (visual, acoustic, lateral line) centers.
Nuclear organization of the bullfrog diencephalon
Authors: Neary Timothy J. , Northcutt R. Glenn
Published: December 2004

A cytoarchitectonic analysis was performed on the diencephalic nuclei of the bullfrog, Rana catesbeiana. The epithalamus contains two widely recognized habenular nuclei. The thalamus has three subdivisions: dorsal and ventral thalamus, and posterior tuberculum. The dorsal thalamus may be further parcelled into anterior, middle, and posterior zones. Connectional data from other studies support this zonation. The anterior zone projects to the telencephalic pallium. The middle zone nuclei receive a strong input from the midbrain roof and project to the telencephalic striatal complex. The posterior zone nuclei do not appear to project to the telencephalon; they may eventually be placed in the pretectum, a transitional area between the diencephalon and mesencephalon. Two of the ventral thalamic populations have been frequently placed in the dorsal thalamus and called the nucleus rotundus and the lateral geniculate nucleus. These terms imply homology with sauropsid dorsal thalamic nuclei, but our analysis and current connectional information do not support such homologies. We have given these populations more neutral names. The hypothalamus is divisible into a preoptic and infundibular hypothalamus, and the preoptic area can be further separated into anterior and posterior preoptic areas. The posterior area contains the magnocellular preoptic nucleus and a dorsal arm of this nucleus, often placed in the ventral thalamus, was recognized. We have tentatively placed the posterior entopeduncular nucleus in the hypothalamus.
Organization of the afferent projections to the Wulst in the pigeon
Authors: Bagnoli Paola , Burkhalter Andreas
Published: December 2004

The afferent connections to the Wulst, a well‐defined bulge in the fore‐brain roof, were studied in the pigeon. Cells of origin were identified by horseradish peroxidase retrograde tracing, after placing multiple injections in the Wulst.

The results demonstrate a bilateral intratelencephalic pathway arising from the archistriatum intermedium (Ai) in the basal forebrain. Labeled cells in n. superficialparvocellularis (SPC) and n. dorsolateralis posterior (DLP) on both sides of the brain, provide anatomical evidence for a bilateral forebrain projection of the somatosensory thalamus. A sparse ipsilateral input of unknown function from the medial thalamus originates in n. dor‐somedialisanterior(DMA)and n. dorsolateralis medialis (DLM).Weprovide confirminge vidence of the bilateral thalamofugal visual pathway ascending from nuclei of the dorsolateral thalamus (DLAmc and DLL). Projections from several brain stem structures are described, including: griseum cen‐trale (GCt), medial and lateral reticular formation (FRM and FRL), area ventralis of Tsai (AVT), n. annularis (Anl), locus coeruleus (LoC), and the avian homologue of the raphe nucleus, n. linearis caudalis (LC).

The account provides a direct anatomical demonstration of a Wulst input from the basal forebrain, the somatosensory thalamus, and the brain‐stem. The projection cells in the brainstem reside in structures known to contribute to ascending catecholaminergic and serotoninergic pathways.
Ascending auditory projections to the inferior colliculus in the adult gerbil, Meriones unguiculatus
Authors: Nordeen K. W. , Killackey H. P. , Kitzes L. M.
Published: December 2004

Ascending auditory projections to the inferiorcolliculus (1C) of the adult gerbil were studied using the retrograde transport of horseradish perpxi‐dase. Our results indicate that in gerbils. The ICreceives afferent projections from most brainstem auditory nuclei. A strong contralateral projection orig‐inates in the cochlenr nuclear complex (CN). A smaller but consistent pro‐jection from all three divisions of ipsilateral CN is also present. The medial superior olive (MSO), superior parolivary nucleus, and ventral nucleus of the lateral lemniscus all maintain ipsilateral projections to the IC. Bilateral projections arise from the lateral superior olive, lateral nucleus of the tra‐pezoid body, and dorsal nucleus of the lateral lemniscus.

Previous investigations in other mammalian species provide conflicting data concerning the magnitude of a direct ipsilateral projection from CN to the IC. Our quantitative data indicate that the ipsilateral projection from CN in the gerbil is nearly one third as large as the projection from ipsilateral MSO. The projection from contralateral CN is six times larger than the MSO projection. The distribution of labeled cells across the rostrocaudal extent of MSO and the three divisions of the cochlear nuclear complex are presented.
Reorganization in granuloprival cerebellar cultures after transplantation of granule cells and glia. II. Ultrastructural studies
Authors: Blank Nathan K. , Seil Fredrick J.
Published: December 2004

Cytosine arabinoside‐induced granuloprival cerebellar cultures lack both granule cells and differentiated glia and demonstrate marked synaptic reorganization. After kainic acid‐exposed cerebellar explants, which contain granule cells and mature glia, were transplanted to the granuloprival cultures, the following ultrastructural features were noted: (1) parallel fibers formed normal synapses with Purkinje cell dendritic spines as well as with basket/stellate cell somata; (2) sprouted Purkinje cell recurrent axon collateral terminals were markedly reduced in number; (3) Purkinje cells matured and lost perisomatic spines; (4) astroglia formed sheaths around Purkinje cell somata and dendrites; and (5) axonal myelination occurred. The transplanted cultures demonstrated ultrastructural restitution toward normal after addition of missing elements.
A crossed corticotectal projection from the lateral suprasylvian area in the cat
Authors: Baleydier Christine , Kahungu Mbwiti , Mauguiere François
Published: December 2004

Crossed 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

A 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

Tectal 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

Postdeafferentation 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

We 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

This 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

Cultured 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

Cultured 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

The 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

Activation 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

One 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

As 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

Es 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

1. Fumarsäure, Bernsteinsäure, Apfelsäure, Oxalessigsäure, Ketoglutarsäure und Citronensäure Können als Kräftige Aktivatoren den oxydativen Abbau von Brenztraubensäure, Milchsäure und Glycero‐phosphorsäure durch zellfreien Rattenleberextrakt katalysieren.
Versuche zur Reinigung der Histidase
Authors: Morel Ch. J.
Published: December 2004

1. Durch Fällung mit Ammoniumsulfat und zweimalige Adsorption an Bleiphosphat lässt sich ein Histidase‐Präparat darstellen, welches Urocaninsäure und Arginin nicht mehr spaltet.
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 Cyclization

Treated 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

On 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.
Verproside, a New Iridoid Glucoside from Veronica officinalis L. (Scrophulariaceae)
Authors: Afifi‐Yazar Fatma Ü. , Sticher Otto
Published: December 2004

A new iridoid glucoside, verproside (2), has been isolated from Veronica officinalis L. and its structure has been established to be 6‐O‐protocatechuoylcatalpol.
Iterative Least‐Squares Lineshape Fitting of 1H‐decoupled 13C‐DNMR.Spectra
Authors: Heinzer Josef , Oth Jean F. M.
Published: December 2004

Iterative least‐squares lineshape fitting of 1H‐decoupled 13C‐DNMR. spectra is advantageously used for the investigation of symmetrical or asymmetrical intramolecular (two‐structure) exchange processes. The least‐squares procedure adopted allows the following parameters to be either optimized by computer or kept constant (according to experimental conditions): the nuclei populations (taking into account line intensity effects resulting from differences in spin‐lattice relaxation times and/or Overhauser enhancements), the corresponding chemical shifts and natural linewidths (characterizing the sites undergoing exchange), the fractional population of one structure (in the case of asymmetrical exchange), one of the chemical rates, the base‐line position, and the base‐line tilt. The relative sensitivity of the lineshape with respect to the fitted parameters as well as the importance of correlations among these parameters have been investigated and tested with examples. The reliability of the kinetic parameters as obtained by the iterative least‐squares lineshape fitting procedure is discussed.
Un nouvel exemple de nucléoside à sucre ramifié insaturé: la désoxy‐3′‐méthylidène‐3′‐adénosine
Authors: Tronchet Jean M. J. , Tronchet Jeannine F.
Published: December 2004

A Novel Example of Unsaturated Branched‐chain Sugar Nucleoside: 3′‐Deoxy‐3′‐methylidene‐adenosine

Starting from 5‐O‐benzoyl‐3‐C‐methylidene‐3‐deoxy‐1,2‐O‐isopropylidene‐α‐D‐erythro‐pentofuranose (11) the title compound 8 has been prepared. Its α‐anomer (9) and the acyclic sugar nucleoside 10 have been obtained as by‐products. Adenosine deaminase slowly deaminated 8, 9 being not affected. Compound 8 exhibited no antiviral activity, whereas one of its saturated analogues (13) inhibited the multiplication of the herpes‐1 (HF) virus.
Dediazoniations of Arenediazonium Ions in Homogeneous Solutions. Part XV. Products of dediazoniation of p‐chlorobenzenediazonium tetrafluoroborate in weakly alkaline aqueous solutions
Authors: Besse Jacques , Schwarz Wolfgang , Zollinger Heinrich
Published: December 2004

The products of decomposition of solutions of p‐chlorobenzenediazonium tetrafluoroborate in aqueous buffer solutions (pH 9.0–10.3; ionic strength 0.1–0.5) at 20.0° have been analyzed quantitatively. Up to eleven low molecular weight compounds could be identified besides the major product, the complex polymeric diazo tar. The distribution of products is influenced by trace amounts of oxygen as well as by p‐chlorophenol and the radical trapping reagent iodoacetic acid. Mechanisms of formation of the products are discussed.
Synthesis of Photoaffinity Labelling Analogues of the Peptide Hormone Bradykinin
Authors: Laczko Endre , Escher Emanuel
Published: December 2004

Fourteen peptides, analogues of bradykinin and (des‐Arg9)bradykinin, have been synthesized by the solid‐phase method or have been obtained through chemical modification. In all these peptides an aromatic residue has been substituted by (4′‐NO2)Phe, (4′‐NH2)Phe, (4′‐N3)Phe or (4′‐NH2‐3′, 5′‐I2)Phe. These peptides will be used as photoaffinity labelling or affinity labelling probes for peptide hormone receptors.
Herstellung von 1, 3‐Diketonen und von Nitro‐diketonen durch (1:1)‐Acylierungen von Lithiumenolaten mit Acylchloriden
Authors: Seebach Dieter , Weller Thomas , Protschuk Gerd , Beck Albert K. , Hoekstra Marvin S.
Published: December 2004

Preparation of 1,3‐Diketones and of Nitro‐diketones by (1:1)‐Acylation of Lithium Enolates with Acyl Chlorides

Slow addition of precooled solutions of lithium enolates in THF (Fig. 1) to solutions of equimolar amounts of acyl chlorides in the same solvent at temperatures between − 80 and − 100° furnishes 1, 3‐diketones in acceptable to good yields (Tables 1−3). Even 3‐nitropropionyl and 4‐nitrobutyryl chloride can be employed for the (1:1)‐acylation of enolates to give the synthetically useful 5‐ and 6‐nitro‐1, 3‐diketones 13 and 25, respectively. The scope and the limitations of this method of preparing 1, 3‐diketones are given and are compared with alternative methods.
Ein neuer Reaktionsweg zu 1, 3‐Dicarbonylderivaten. Modelluntersuchungen am A/B‐Teil von 3‐Oxo‐5α‐steroiden
Authors: Berbalk Hans , Eichinger Karl , Winetzhammer Willibald
Published: December 2004

A New Route to 1, 3‐Dicarbonyl Derivatives, Model Investigations on the A/B‐Part of‐3‐Oxo‐5α‐steroids

Starting from 1 the 1, 3‐dicarbonyl compounds 4a–d were synthetized via the enynes 2a–e and the relatively unstable epoxides 3a–d. The latter were reacted with 95% formic acid to gave 4a–d; small amounts of the furane derivatives 5a–c were identified as by‐products in this last step. In the presence of catalytic amounts of HgSO4 the epoxides 3a–c yielded with 95% formic acid the furanes 5a–c, but no detectable amounts of 4a–c.