bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Undergraduate‐Postgraduate Interface
Authors: Vrotsos IA 
Published: April 2006

The goal of dental education, since the mid‐19th century when the first Dental Schools appeared in Europe and America, has been to produce dentists able to carry out established dental therapies and serve the needs of patients. The range of content of Dental Education has been changing radically every 20–30 years, but especially in the last half of the 20th century, the need for constant reassessment, modification and amendment of dental curricula became apparent.Hence, after the 1950s it became clear that dental curricula were not able to provide the breadth of knowledge and clinical expertise that had accumulated in certain areas in dentistry, such as oral surgery and orthodontics. This resulted in the appreciation of the need for organising and establishing university or non‐university courses which would provide dentists with the additional specialised knowledge within a timeframe of two and later three years.This marked the birth of postgraduate programmes. Fifty years later, and based on the experience that has accumulated mainly from the ‘dentally developed’ countries in Western Europe and USA we can say that the ‘philosophy’ of dental postgraduate education remains largely the same. In other words, the main aim of postgraduate programmes remains to provide knowledge and practical skills in specialised areas of dentistry with the purpose of creating (i) clinical practitioners specialised in specific areas (specialisation, specialty) and (ii) general dentists with a strong scientific background, able to provide original research in basic sciences and with the necessary training and experience in organising and delivering dental education.As a general rule, postgraduate education is not antagonistic to undergraduate education, but on the contrary, it represents an extension of the knowledge acquired in undergraduate education into specific areas of interest and in certain directions. It is generally accepted that advanced postgraduate education can be successfully accomplished only on the basis of a complete, well‐organised undergraduate education. In the absence of this basis, the effectiveness of postgraduate programmes in succeeding in their goals can only be limited. This has been proved many times, at least in the USA, during the final evaluation (final performance) of postgraduate students coming from ‘dentally developed’ countries, in comparison with students having a low level of undergraduate education. Hence at the beginning of the 21st century, we can affirm that the efforts for good administration, high curriculum level and clear goals of postgraduate studies must be based on a well‐structured, well‐functioning and productive undergraduate dental education systems.
Impact of alternate definitions of fever resolution on the composite endpoint in clinical trials of empirical antifungal therapy for neutropenic patients with persistent fever: analysis of results from the Caspofungin Empirical Therapy Study
Authors: De Pauw B.E. , Sable C.A. , Walsh T.J. , Lupinacci R.J. , Bourque M.R. , Wise B.A. , Nguyen B.‐Y. , DiNubile M.J. , Teppler H. 
Published: April 2006

Abstract: Background. Sensitivity analyses were incorporated in a Phase III study of caspofungin vs. liposomal amphotericin B as empirical antifungal therapy for febrile neutropenic patients to determine the impact of varying definitions of fever resolution on response rates.Methods. The primary analysis used a 5‐part composite endpoint: resolution of any baseline invasive fungal infection, no breakthrough invasive fungal infection, survival, no premature discontinuation of study drug, and fever resolution for 48 h during the period of neutropenia. Pre‐specified analyses used 3 other definitions for fever resolution: afebrile for 24 h during the period of neutropenia, afebrile at 7 days post therapy, and eliminating fever resolution altogether from the composite endpoint. Patients were stratified on entry by use of antifungal prophylaxis and risk of infection. Allogeneic hematopoietic stem cell transplants or relapsed acute leukemia defined high‐risk patients.Results. In the primary analysis, 41% of patients in each treatment group met the fever‐resolution criteria. Low‐risk patients had shorter durations of neutropenia but failed fever‐resolution criteria more often than high‐risk patients. In each exploratory analysis, response rates increased in both treatment groups compared to the primary analysis, particularly in low‐risk patients.Conclusions. Response rates for the primary composite endpoint for both treatment groups in this study were driven by low rates of fever resolution. Requiring fever resolution during neutropenia in a composite endpoint can mask more clinically relevant outcomes.
Basic Fibroblast Growth Factor in the Adrenal Gland
Authors: Blottner Dieter , Westermann Reiner , Grothe Claudia , Böhlen Peter , Unsicker Klaus 
Published: April 2006

AbstractThe importance of trophic agents for the development and maintenance of neurons and their presence in mesenchyme‐derived neuronal target organs such as muscle is well exemplified by the protein nerve growth factor (NGF) and its synthesis in target areas of sympathetic and sensory nerves. Stringent conceptualization of target organ‐regulated neuronal maintenance would imply that neurons were able to provide trophic support to their presynaptic counterparts. We present data suggesting that basic fibroblast growth factor (bFGF), a mitogen and trophic factor for several neuron populations in vitro, may be such a protein involved in retrograde trophic neuron‐neuron interaction. Basic FGF or a closely related protein is present in the adrenal medulla and its sympathetic neuron‐like chromaffin cells. A polyclonal antibody specific for bFGF recognizes an 18 kD band in Western blots of bFGF‐enriched bovine adrenal medulla extracts and immunostains isolated bovine chromaffin cells. This antibody also blocks the bFGF‐like activity present in adrenal medullary extracts and chromaffin granule extracts that both promote in vitro survival of embryonic chick ciliary ganglionic neurons. Furthermore, like bFGF, the soluble proteins of bovine chromaffin granules are mitogenic for cultured bovine aorta endothelial cells. Electrothermal unilateral destruction of the adrenal medulla causes the disappearance of 25% of Nissl‐stained neurons in the ipsilateral intermediolateral column (IML) of the spinal cord between levels Th7 and L1, which contains the preganglionic neurons projecting to the adrenal medulla. Substitution of the adrenal medulla by gel foams soaked with bFGF prevents neuron losses in the IML. The effects are specific in that NGF and cytochrome C are ineffective. Our results suggest that bFGF is located in chromaffin cells and maintains target‐deprived autonomic spinal cord neurons, thus possibly acting as an interneuronal trophic messenger in vivo.
Climbing Fibre Plasticity in the Cerebellum of the Adult Rat
Authors: Rossi F. , Wiklund L. , van der Want J. J. L. , Strata P. 
Published: April 2006

AbstractThe present paper reports an example of collateral sprouting, and provides a detailed morphological description of newly formed axonal branches, terminal arborizations, and synapses in the central nervous system of an adult mammal. By means of the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA‐L), we demonstrate that the climbing fibres, which survive a subtotal lesion of the inferior olive in the rat, emit collateral sprouts and develop new terminal plexuses forming new synaptic contacts on Purkinje cell dendrites. Adult climbing fibres thus show striking plastic capabilities that represent the morphological basis of the functional reinnervation of Purkinje cells.
Multiple Purkinje Cell Recording in Rodent Cerebellar Cortex
Authors: Sasaki K. , Bower J. M. , Llinás R. 
Published: April 2006

AbstractThe spatial and temporal organization of climbing fibre activation of Purkinje cells, the so‐called complex spikes, were studied in the rat cerebellar Crus II folium utilizing a multiple microeletrode recording technique. As many as 32 Purkinje cells could be simultaneously recorded by using a custom‐built electronic amplifier system and a special data storage device. Analysis of the auto‐correlation activity of complex spikes in any given group of Purkinje cells indicated that activation occurs with a particular rhythmicity having a base firing of 10 Hz. Cross‐correlation of spontaneous complex spikes demonstrated, in addition to a particular rhythmicity, an extraordinarily high degree of synchronicity within a particular spatial distribution of Purkinje cells. Thus, Purkinje cells organized in rostra‐caudal rows tend to fire within 1 ms of each other for distances as far as 800 μm (the width of a folium) from the ‘master’ neuron. By contrast, Purkinje cells located medial or lateral to the master neuron showed almost no cross‐correlation. Administration of harmaline to the animal increased the degree of auto‐ and cross‐correlation but did not change the spatial order of the distribution of the cross‐correlation. The results indicate that the olivo‐cerebellar system is organized in such a way that climbing fibre afferents may be activated in a close‐to‐synchronous and rhythmic fashion. The spatial distribution of these afferents over the cortex is such as to activate rostro‐caudal bands of Purkinje cells which tend to fire in a close‐to‐synchronous manner.
Regional‐ and Age‐Specific Neurochemical Alterations in Rats Rendered Microencephalic by Differentially Timed Gestational Methylazoxymethanol Treatment
Authors: Virgili M. , Barnabei O. , Contestabile A. 
Published: April 2006

AbstractRats with different degrees of microencephaly were obtained by injecting pregnant mothers with methylazoxymethanol acetate (MAM) at gestational days 13.5 or 16.5. Specific markers for cholinergic (choline acetyltransferase, ChAT), GABAergic (glutamate decarboxylase, GAD), and glutamatergic (D‐3H aspartate high affinity uptake) neurons, were measured in several brain regions (cortex, hippocampus, anterior and posterior striatum, medial septum plus nucleus of the diagonal band, globus pallidus) in young and adult microencephalic rats. In adult rats born to mothers injected with MAM at gestational day 16.5 (G 16.5) ChAT level was increased in the cortex, hippocampus and striatum but decreased in the septal complex; GAD was decreased in the globus pallidus and, to a little extent, in the hippocampus while D‐3H aspartate uptake was decreased in the striatum. One month old rats belonging to the same group showed comparable differences with the exception of larger increase of ChAT in the cortex and striatum. In adult rats born from mothers injected with MAM at gestational day 13.5 (G13.5) differences in the cholinergic marker were in general less pronounced; GAD was not decreased in the globus pallidus and D‐3H aspartate uptake was unchanged in the striatum but significantly decreased in the hippocampus. The results are correlated with morphological brain alterations caused by differentially timed MAM treatment and with available information on the generation time of various neuronal populations. They show that the balance between different neurotransmitter systems can be experimentally altered and suggest that MAM treatment may provide an experimental tool for studying the development of this balance.
Calibre and Microtubule Content of the Non‐Medullated and Myelinated Domains of Optic Nerve Axons of Rats
Authors: Hernández Carolina , Blackburn Eileen , Alvarez Jaime 
Published: April 2006

AbstractCalibres and microtubule contents of the non‐medullated and myelinated domains of optic nerve axons of adult rats were studied with the electron microscope. The cross‐sectional areas of the non‐medullated domain was 0.25 μm2, and that of the myelinated domain 0.40 μm2, that is, greater by 59%. The increase in size was uneven across the axonal population; it was marked in fine and medium sized axons, and modest in the largest axons. The number of microtubules increased with axonal size; the density, however, decreased from 85 mirotubules/μm2 axons to about 20 in 1.2 μm2 axons. In axons of equal cross sectional area, the microtubular density of the myelinated and non‐medullated domains was the same. Microtubular density values of optic axons resemble those of dorsal roots more than those of peripheral nerve axons of equal calibre. The facts that optic axons increase in size and gain microtubules behind the eyeball while the microtubular packing decreases suggest a local regulation of the axonal cytoskeleton.
Glycoprotein Synthesis Is Necessary for Memory of Sickness‐Induced Learning in Chicks
Authors: Barber Alistair J. , Gilbert David B. , Rose Steven P. R. 
Published: April 2006

AbstractCan current biochemical models of memory account for sickness‐induced learning? We show that chicks can form an association between pecking a coloured but tasteless lure and becoming ill (LiCI, i.p.) 30 min later. We go on to demonstrate amnesia for this association, induced by intracranial administration of 2‐deoxygalactose (10 μmole per hemisphere, in a 10 γl vol), an inhibitor of the synthesis of glycoproteins of the synaptic membrane, 10 min before pecking. Further, we show that this 2‐deoxygalactose‐induced amnesia is not state dependent. Thus the brain representation of the lure must be held, and require macromolecular syntheses, similar to those found in other forms of learning, for a considerable time before it can be associated with new significant experience. This is incompatible with contiguous synaptic firing views of memory.
Survival and Axonal Elongation of Adult Rat Retinal Ganglion Cells
Authors: Thanos Solon , Bähr Mathias , Barde Yves‐Alain , Vanselow Jens 
Published: April 2006

AbstractA peripheral nerve exudate, collected in situ from the proximal end of a severed rat sciatic nerve, can induce substantial axonal elongation from ganglion cells when tested on explanted adult rat retinae. The responsive cells are identified on the basis of their Thy 1.1 immunostaining properties. Similar outgrowth can be obtained from explants when the culture medium is supplemented with brain‐derived neurotrophic factor (BDNF). In addition, both BDNF and the sciatic nerve exudate can prevent ganglion cell degeneration as shown by the retrograde transport of a fluorescent dye that had been applied to the superior colliculus prior to explantation. The results demonstrate that soluble components, released by lesioned peripheral nerves, can effect adult retinal ganglion cells in a way that is reminiscent of that which has been described in vivo using sciatic nerve grafts after sectioning of the optic nerve. The molecular nature of these components is discussed.
Fos‐Like Immunoreactivity Induced by Seizure in Mice Is Specifically Associated With Euchromatin in Neurons
Authors: Mugnaini Enrico , Berrebi Albert S. , Morgan James I. , Curran Tom 
Published: April 2006

AbstractAdministration of convulsant drugs causes the rapid induction of c‐fos in identified neurons within the mouse central nervous system (Morgan et al., 1987). In particular, Fos‐like immunoreactivity is evident in nuclei of granule cells of the hippocampal dentate gyrus within 30 minutes of the onset of seizure. By immunoelectron microscopy, Fos antibody binding was exclusively localized to dispersed chromatin (euchromatin) of several types of projection neurons and local circuit neurons in various brain regions and especially in the dentate gyrus, 210 minutes after a single injection of Metrazol. Fos‐like immunoreactivity was not detectable in the nucleolus, nor in the characteristic peripheral and nucleolus‐associated heterochromatin of hippocampal granule cells. No immunostaining was observed in nuclei of glial, ependymal or endothelial cells, and no cytoplasmic reactivity was seen in any cell type. These findings support a role for Fos in stimulus‐response coupling at the level of transcriptional regulation in neurons.
Physiological and Ultrastructural Characterization of a Central Synaptic Connection between Identified Motor Neurons in the Locust
Authors: Burrows M. , Watson A. H. D. , Brunn D. 
Published: April 2006

AbstractAn excitatory connection between an extensor and several flexor tibiae motor neurons that innervate antagonistic muscles in the hind leg of a locust has been characterized using physiological and ultrastructural methods. Simultaneous intracellular recordings from the single fast extensor (FETi) motor neuron and up to three flexor motor neurons show that a spike in FETi is followed by a short latency depolarizing synaptic potential in the flexors that is powerful enough to evoke a burst of flexor spikes. The chemically mediated excitatory postsynaptic potential (EPSP) is caused centrally as it persists when sensory feedback from the leg is removed, and has a latency of 1.6–2.0 ms depending upon the position of the recording electrodes in the somata or neuropilar segments of the pre‐ and postsynaptic neurons. The amplitude of the EPSP declines gradually in a saline containing no calcium but high magnesium, indicating that no spiking interneuron is interposed in the pathway. With repetitive stimulation, the EPSP decrements markedly so that at intervals of 50 ms the second EPSP of a pair is reduced by 90%. The amplitude of the EPSP is also dependent on the amplitude of the presynaptic spike.The physiological evidence suggesting a monosynaptic connection is directly confirmed by electron microscopy of ganglia in which FETi and a flexor were both labelled with horseradish peroxidase. Direct chemical synapses between the two identified neurons, in which FETi is the presynaptic element, occur in three regions of the neuropil examined. At a synapse, the flexor motor neuron may be the only postsynaptic neuron or it may be one element in a dyad. The synaptic arrangements between the two neurons are complex with serial synapses through unlabelled processes linking FETi to flexor motor neurons and with frequent reciprocal synaptic connections between FETi and unlabelled processes. Unidentified processes also make input synapses on both neurons close to the synapses from FETi.The behavioural significance of the connection lies in the mechanical requirements for kicking and jumping. To prepare for these powerful movements the extensor and flexor tibiae muscles must co‐contract. The connection from FETi enhances the depolarization and frequency of spikes in the flexors during the co‐contraction.
Effects of Pertussis Toxin Suggest a Role for G‐Proteins in the Inhibition of Acetylcholine Release from Rat Myenteric Plexus by Opioid and Presynaptic Muscarinic Receptors
Authors: Doležal V. , Tuček S. , Hynie S. 
Published: April 2006

Abstract

Longitudinal muscle preparations of the rat ileum with the attached myenteric plexuses (LMMPs) were preloaded with (3H)choline and the effects of drugs on the depolarization‐evoked release of radioactivity corresponding to (3H) acetylcholine ((3H)ACh) were measured. The release of (3H)ACh was inhibited by morphine and the effect of morphine was blocked by naloxone. Morphine had no effect on the release of (3H)ACh in LMMPs from rats that had been injected with pertussis toxin (PTX) 7 days before experiments.
Carbamoylcholine applied in the presence of tetrodotoxin inhibited the release of (3H)ACh evoked by depolarization of LMMPs. The effect of carbamoylcholine was absent in LMMPs from rats pretreated with PTX.
The effects of PTX indicate that one or more PTX‐sensitive G proteins are involved in the chain of events mediating the action of opioid and muscarinic receptors on the release of ACh from the myenteric plexus. It is suggested that the inhibition of ACh release depends on G‐protein‐mediated coupling of opiod receptors with K+ channels and of muscarinic receptors with Ca2+ channels, but alternative explanations cannot be excluded.
Cholecystokinin: Corelease with dopamine from nigrostriatal neurons in the cat
Authors: Artaud F. , Baruch P. , Stutzmann J. M. , Saffroy M. , Godeheu G. , Barbeito L. , Hervé D. , Studler J. M. , Glowinski J. , Chéramy A. 
Published: April 2006

AbstractHalothane‐anaesthetized cats were implanted with push‐pull cannulae to demonstrate the in vivo release of cholecystokinin‐like immunoreactivity (CCK‐LI) in the substantia nigra and the ipsilateral caudate nucleus. The spontaneous and the calcium‐dependent potassium‐evoked release of CCK‐LI were observed in both structures. In addition, the local application of tetrodotoxin (10−6 M) reduced the spontaneous release of the peptide. 6‐OHDA lesions made in the substantia nigra pars compacta led to a complete destruction of nigrostriatal dopaminergic neurons. CCK‐LI levels were not affected in the caudate nucleus but were reduced substantially in the substantia nigra. The activation of dopaminergic cells induced by the nigral application of alpha‐methyl‐para‐tyrosine (10−4 M) stimulated the release of CCK‐LI and dopamine in the ipsilateral caudate nucleus, whilst opposite effects were seen in the substantia nigra. Similar results were obtained when dopaminergic transmission was blocked in the caudate nucleus suggesting that the evoked release of CCK‐LI by the alpha‐methyl‐para‐tyrosine treatment originates from dopaminergic nerve terminals and not from other CCK‐LI containing fibres in response to released dopamine. Dopamine (10−7 M) as well as the D1 agonist SKF 38393 (10−5 M) stimulated CCK‐LI release when applied into the caudate nucleus while the D2 agonist, LY 171555 (10−6 M) slightly reduced peptide release. The local application of cholecystokinin‐8 sulfate (CCK‐8S) (10−8 M, for 30 min) into the substantia nigra pars compacta increased the firing rate of dopaminergic cells and stimulated the release of newly synthesized 3H‐dopamine from dendrites and nerve terminals.These results suggest, but do not definitively prove, that, in the cat, CCK‐LI and dopamine are coreleased from nigrostriatal mixed dopaminergic/CCK‐LI neurons and that CCK‐LI released from dendrites is, like dopamine, involved in the regulation of the activity of these cells.
Non‐Competitive Antagonism of N‐Methyl‐D‐Aspartate by Displacement of an Endogenous Glycine‐Like Substance
Authors: Fletcher E. J. , Millar J. D. , Zeman S. , Lodge D. 
Published: April 2006

AbstractN‐methyl‐D‐aspartate (NMDA; 40 μM) induced depolarizations of cortical wedges that were reduced by 30–60% in the presence of D‐2‐amino‐5‐phosphonovalerate (D‐AP5; 5 μM), ketamine (5 μM), dextrorphan (5 μM), magnesium (500 μM), kynurenate (200 μM), and 1‐hydroxy‐3‐aminopyrrolidone‐2 (HA‐966; 200 μM). Superfusion with glycine (1 μM‐1 mM) did not enhance the action of NMDA in control medium and in media containing D‐AP5, ketamine, dextrorphan, or magnesium. In the presence of kynurenate and HA‐966, however, NMDA‐induced depolarizations were enhanced in a dose‐dependent manner by glycine (10 μM‐3.16 mM). NMDA antagonism produced by HA‐966 appeared to be more completely reversed than that produced by kynurenate. This action of glycine was mimicked by D‐serine but not by GABA or L‐serine, and was resistant to strychnine (10–50 μM). Reduction of responses to quisqualate by kynurenate was not reversed by glycine.In these cortical wedges, spontaneous synaptic activity was observed in nominally magnesium‐free medium and this epileptiform activity could be blocked by the above NMDA antagonists. Glycine and D‐serine reversed only the effects of kynurenate and HA‐966 on such synaptic activity.These results suggest there is an endogenous glycine‐like compound acting on NMDA receptor‐ionophore complexes and that displacement of this compound by HA‐966 or kynurenate produces antagonism of NMDA.