bluuebunny/crossref_metadata_2025_split huggingface dataset:
Somatotopic mapping of chordotonal organ neurons in a primitive ensiferan, the New Zealand tree weta Hemideina femorata: II. complex tibial organ
Authors: Nishino Hiroshi , Field Laurence H. 
Published: July 2003

AbstractMost ensiferan insects possess sets of highly specialized chordotonal organs in the proximal tibiae to detect conspecific auditory/vibratory signals or approach of predators. To date, most auditory/vibratory afferents have been classified according to their physiological properties and axonal projection morphology, but not to somatotopic origins. Hence, the functional specialization of identified receptor cells in the tibial organs remains uncertain. To address this question from an anatomical aspect, we investigated the structure of the weta, Hemideina femorata, tibial organs (the most elaborated tibial chordotonal organs among ensiferans) and their central projections by staining small numbers of receptor afferents from identified tibial organs. These organs comprise the “complex tibial organ,” including the subgenual organ (primary vibration detector) and its posterior complement, the accessory organ, and the crista acustica (primary auditory organ) and its proximal complement, the intermediate organ. Unlike reports of a membranous organ structure for homologs in other ensiferans, weta tibial organs contain receptor cells embedded in thick solid masses. Primary afferents project ipsilaterally to the medial ventral association center of thoracic ganglia, where axon terminals are arrayed topographically in different areas specific to each organ, except for almost complete overlap of afferents originating from the distal part of the crista acustica and from the intermediate organ. In contrast to somatotopic reflection of sensilla position on limbs, as known for mechanoreceptor hairs, the somatotopic projection map of the insect ear reveals topographic association with acoustic tracheae or tibial cuticular attachment sites, which in turn must reflect determinants of response sensitivity (e.g., frequency or threshold). J. Comp. Neurol. 464:327–342, 2003. © 2003 Wiley‐Liss, Inc.
Spontaneous regeneration of the corticospinal tract after transection in young rats: Collagen type IV deposition and astrocytic scar in the lesion site are not the cause but the effect of failure of regeneration
Authors: Iseda Tsutomu , Nishio Takeshi , Kawaguchi Saburo , Kawasaki Takayuki , Wakisaka Shinichiro 
Published: July 2003

AbstractIn young rats the corticospinal tract regenerated after a single transection of the spinal cord with a sharp blade, but regeneration failed if the transection was repeated to make a more traumatic injury. To identify cells and associated molecules that promote or impede regeneration, we compared expression of collagen type IV, glial fibrillary acidic protein (GFAP), and vimentin immunoreactivity (IR) at the lesion sites in combination with anterograde axonal tracing between animals with two types of transection. Axonal regeneration occurred as early as 18 hours after transection; regenerating axons penetrated vessel‐like structures with collagen type IV‐IR at the lesion site, while reactive astrocytes coexpressing GFAP‐ and vimentin‐IR appeared in the lesioned white matter. In contrast, when regeneration failed astrocytes were absent near the lesion. By 7 days sheet‐like structures with collagen type IV‐IR and astrocytic scar appeared in the lesioned white matter and persisted until the end of the observation period (31 days). On the basis of their spatiotemporal appearance, collagen type IV‐IR sheet‐like structures and the astrocytic scar follow, rather than cause, the failure of regeneration. The major sign, and perhaps cause, of failure of axonal regeneration is likely the prolonged disappearance of astrocytes around the lesion site in the early postinjury period. J. Comp. Neurol. 464:343–355, 2003. © 2003 Wiley‐Liss, Inc.
Increased expression of insulin‐like growth factor I augments the progressive phase of synaptogenesis without preventing synapse elimination in the hypoglossal nucleus
Authors: O'Kusky John Robert , Ye Ping , D'Ercole A. Joseph 
Published: July 2003

AbstractThe in vivo actions of insulin‐like growth factor I (IGF‐I) on synaptogenesis in the hypoglossal nucleus were investigated in transgenic mice that overexpress IGF‐I in the brain postnatally and in normal nontransgenic littermate controls. In a previous study using these mice, we found that IGF‐I increases the total volume of the hypoglossal nucleus by increasing the volume of neuropil rather than by increasing total neuron number; therefore, the progressive and regressive phases of synaptogenesis could be evaluated without the confounding effects of altered neuron number. The volume of the hypoglossal nucleus was significantly increased by 28% to 59% in transgenic mice after postnatal day (P) 7, whereas the total number of hypoglossal neurons did not differ significantly from controls. The numerical density of neurons was significantly decreased by 21% to 38% after P7, and the density of myelinated axons was significantly increased by 19%. Although the numerical density of synapses did not differ between groups at any age, the total number of synapses in transgenic mice was increased by 42% to 52% after P14. Total synapse number in controls increased from P7 (7.9 million) to peak values at P21 (36.0 million), followed by a significant decrease (33%) at P130 (24.2 million). In transgenic mice, total synapses increased from 8.2 million on P7 to 51.1 million on P21, followed by a significant decrease (28%) to 36.7 million at P130. Our results demonstrated that IGF‐I can stimulate a persistent increase in the number of hypoglossal synapses, thereby augmenting the progressive phase of synaptogenesis without preventing synapse elimination during the regressive phase. J. Comp. Neurol. 464:382–391, 2003. © 2003 Wiley‐Liss, Inc.
ERMs colocalize transiently with L1 during neocortical axon outgrowth
Authors: Mintz C. David , Dickson Tracey C. , Gripp Mark L. , Salton Stephen R.J. , Benson Deanna L. 
Published: July 2003

AbstractL1 is a member of the Ig superfamily of cell adhesion molecules (CAMs) that functions in many aspects of neuronal development including axonal outgrowth and neuronal migration. These functions require coordination between L1 and the actin cytoskeleton. Because CAMs and the cytoskeleton do not bind directly, membrane–cytoskeletal linkers (MCLs) such as ankyrin are thought to be crucial to their interactions, but data from a knockout mouse suggest that ankyrin is not necessary for the earliest events attributed to L1 function. Recent findings in hippocampal cell culture show that members of the ERM family of proteins (ezrin, radixin, and moesin) can also serve as MCLs between L1 and actin in neurons. Here, we demonstrate that ERM proteins are expressed in extending neuronal processes in the intermediate zone of the developing cortex, a region that is densely packed with migrating neurons and growing axons. ERMs and L1 are codistributed extensively over a transient time course that coincides with rapid axon growth and cortical expansion. This codistribution is strong at embryonic day 17 and 19 but diminishes by postnatal day 0, at which time ankyrin‐L1 codistribution increases dramatically. These findings suggest that in the developing neocortex, ERMs are the predominant MCL for L1 during migration and axon extension, neither of which requires ankyrin function. Furthermore, these data suggest that there is a developmentally regulated switch in MCL function in the developing brain. J. Comp. Neurol. 464:438–448, 2003. © 2003 Wiley‐Liss, Inc.
Rearrangement of synaptic connections with inhibitory neurons in developing mouse visual cortex
Authors: Yamashita Akiko , Valkova Katia , Gonchar Yuri , Burkhalter Andreas 
Published: July 2003

AbstractCortical inhibition is determined in part by the organization of synaptic inputs to γ‐aminobutyric acidergic (GABAergic) neurons. In adult rat visual cortex, feedforward (FF) and feedback (FB) connections that link lower with higher areas provide ∼10% of inputs to parvalbumin (PV)‐expressing GABAergic neurons and ∼90% to non‐GABAergic cells (Gonchar and Burkhalter [1999] J. Comp. Neurol. 406:346–360). Although the proportions of these targets are similar in both pathways, FF synapses prefer larger PV dendrites than FB synapses, which may result in stronger inhibition in the FF than in the FB pathway (Gonchar and Burkhalter [1999] J. Comp. Neurol. 406:346–360). To determine when during postnatal (P) development FF and FB inputs to PV and non‐PV neurons acquire mature proportions, and whether the pathway‐specific distributions of FF and FB inputs to PV dendrites develop from a similar pattern, we studied FF and FB connections between area 17 and the higher order lateromedial area (LM) in visual cortex of P15–42 mice. We found that the innervation ratio of PV and non‐PV neurons is mature at P15. Furthermore, the size distributions of PV dendrites contacted by FF and FB synapses were similar at P15 but changed during the third to sixth postnatal weeks so that, by P36–42, FF inputs preferred thick dendrites and FB synapses favored thin PV dendrites. These results suggest that distinct FF and FB circuits develop after eye opening by rearranging the distribution of excitatory synaptic inputs on the dendritic tree of PV neurons. The purpose of this transformation may be to adjust differentially the strengths of inhibition in FF and FB circuits. J. Comp. Neurol. 464:426–437, 2003. © 2003 Wiley‐Liss, Inc.
Regenerating crayfish motor axons assimilate glial cells and sprout in cultured explants
Authors: Pearce Joanne , Lnenicka Gregory A. , Govind C.K. 
Published: July 2003

AbstractPhasic and tonic motor nerves originating from crayfish abdominal ganglia, in 2–3‐day‐old cultured explants, display at their transected distal ends growth zones from which axonal sprouts arise. The subcellular morphology of this regenerative response was examined with thin serial‐section electron microscopy and reveals two major remodeling features. First, the external sprouts that exit the nerve are a very small part of a much more massive sprouting response by individual axons comprising several orders of internal sprouts confined to the nerve. Both internal and external sprouts have a simple construction: a cytoskeleton of microtubules and populations of mitochondria, clear synaptic vesicles, membranous sacs, and extrasynaptic active zone dense bars, features reminiscent of motor nerve terminals. Close intermingling of the sprouts of several axons give rise to a neuropil‐like arbor within the nerve. Thus, extensive sprouting is an intrinsic response of crayfish motor axons to transection. Second, an equally dramatic remodeling feature is the appearance of nuclei, which resemble those of adjacent glial cells, within the motor axons. These nuclei often appear where the adjoining membranes of the axon and glial cell are disrupted and where free‐standing lengths of the double membrane are present. These images signify a breakdown of the dividing membranes and assimilation of the glial cell by the axon, the nucleus being the most visible sign of such assimilation. Thus, crayfish motor axons respond to transection by assimilating glial cells that may provide regulatory and trophic support for the sprouting response. J. Comp. Neurol. 464:449–462, 2003. © 2003 Wiley‐Liss, Inc.
Synaptic and morphologic properties in vitro of premotor rat nucleus tractus solitarius neurons labeled transneuronally from the stomach
Authors: Glatzer Nicholas R. , Hasney Christian P. , Bhaskaran Muthu D. , Smith Bret N. 
Published: July 2003

AbstractNeurons in the rat nucleus tractus solitarius (NTS) possess morphologic characteristics that have been correlated with the type of synaptic information they receive. These features have been described for viscerosensory neurons but not for premotor NTS neurons. The morphologic and synaptic features of neurons in the rat caudal NTS were assessed using whole‐cell patch‐clamp recordings and biocytin labeling in brainstem slices. Gastric‐related premotor NTS neurons were identified for recording after inoculation of the stomach wall with a transneuronal retrograde viral label that reports enhanced green fluorescent protein. Three morphologic groups of NTS neurons were identified based on quantitative aspects of soma area and proximal dendritic arborization, measures that were consistent across slice recordings. The most common type of cell (group I) had relatively small somata and one to three sparsely branching dendrites, whereas the other groups had larger somata and more than three dendrites, which branched predominantly close to (group II) or distant from (group III) the soma. Voltage‐clamp recordings revealed spontaneous excitatory and inhibitory postsynaptic currents in all neurons, regardless of morphology. Gastric‐related premotor NTS neurons composed two of the three morphologic types (i.e., groups I and II). Compared with unlabeled neurons, these cells were less likely to receive constant‐latency synaptic input from the tractus solitarius. These results refute the hypothesis that general patterns of synaptic input to NTS neurons depend on morphology. Gastric premotor neurons comprise a subset of NTS morphologic types, the organization of the viscerosensory input to which has yet to be defined. J. Comp. Neurol. 464:525–539, 2003. © 2003 Wiley‐Liss, Inc.
Effects of lipid oxidation on fish lipids — amylopectin interactions
Authors: Bienkiewicz Grzegorz , Kołakowska Anna 
Published: July 2003

AbstractThe results of studies on fish lipid oxidation effects on lipid‐amylopectin starch interactions are presented. Particular attention is paid to fish lipid availability (extractability from the system) and fatty acid contributions to individual lipid groups after mixing‐provoked interaction and after a 30‐day storage at —18 °C. The study involved model systems containing fish lipids at different levels of oxidation, lipids containing an antioxidant (BHA), and gelatinised amylopectin starch in a 10% aqueous solution. The lipid to starch ratio was 1:1. The test systems were subjected to selective extraction. The extracts were assayed for lipid content, peroxide value, anisidine value, fluorescence, and fatty acid composition.Compared to fresh fish lipids, those lipids, which were oxidised to a higher extent were shown to be more amenable to complexing with amylopectin, but they were also more readily released during frozen storage. On the other hand, addition of BHA stabilised the lipid‐amylopectin starch interaction during storage at —18 °C.In the entire systems tested, polyunsaturated fatty acids, eicosapentaenoic and docosahexaenoic acids in particular, proved to be most susceptible to binding, up to 90% of the latter being complexed.
Antioxidant activity of evening primrose phenolics in sunflower and rapeseed oils
Authors: Schmidt Štefan , Niklová Ivana , Pokorný Jan , Farkaš Pavel , Sekretár Stanislav 
Published: July 2003

AbstractCrude ethanol/ethyl acetate extracts of industrial evening primrose (Oenothera biennis L.) seed meal were separated into six fractions using the Sephadex LH‐20 column chromatography and 96% aqueous ethanol as a mobile phase. Their antioxidant activities were tested in sunflower and rapeseed oils by using an Oxidograph apparatus at a temperature of 110 °C. Only the fractions III and IV displayed a pronounced antioxidant activity while the other fractions were either inactive or even pro‐oxidative. The active fractions contained phenolic acids and their esters; gallic acid, methyl and ethyl gallates, protocatechuic acid and its methyl ester were identified by GC/MS. Catechin was present, too, but exhibited only moderate antioxidant activity in sunflower oil.
Enantioseparation of warfarin and its metabolites by capillary zone electrophoresis
Authors: Zhou Qingyu , Yau Wai‐Ping , Chan Eli 
Published: July 2003

AbstractA capillary zone electrophoresis (CZE) method with direct ultraviolet (UV)‐absorbance detection is presented for the simultaneous enantiomeric separation of warfarin and its main metabolites, including warfarin alcohols, 4’‐, 6‐, and 7‐hydroxywarfarin, using highly sulfated β‐cyclodextrin (HS‐β‐CD) as the chiral selector. This chiral separation method was optimized in terms of the electrophoretic parameters, which included the concentration of HS‐β‐CD used, the type and composition of organic modifier added to the background electrolyte (BGE) buffer, and the BGE buffer pH. Chiral separation of warfarin and its major metabolites was achieved with high resolution, selectivity, efficiency, repeatability, and reproducibility. This optimized chiral analysis of warfarin along with its metabolites was completed within a satisfactory electrophoresis time of 20 min.
Chiral electromigration methods in food analysis
Authors: Simó Carolina , Barbas Coral , Cifuentes Alejandro 
Published: July 2003

AbstractThis review article addresses the different chiral capillary electrophoretic methods that are being used for the study and characterization of foods and food compounds (e.g., amino acids, organic acids, sugars, pesticides). An updated overview, including works published till December 2002, on the principal applications of enantioselective procedures together with their main advantages and drawbacks in food analysis is provided. Some anticipated applications of chiral electromigration methods in food characterization are also discussed.
Quantitation of talinolol and other β‐blockers by capillary electrophoresis for in vitro drug absorption studies
Authors: Awadallah Bilal , Schmidt Peter C. , Holzgrabe Ulrike , Wahl Martin A. 
Published: July 2003

AbstractA capillary zone electrophoresis method is described for the enantioseparation of talinolol using heptakis(2,3‐diacetyl‐6‐sulfo)‐β‐cyclodextrin (HDAS‐β‐CD) as a chiral selector. After liquid‐liquid extraction of talinolol from physiological solution, electrokinetic injection was employed to improve the sensitivity. The use of a coated capillary was necessary to achieve stable and reproducible enantioseparations. A baseline separation of the talinolol enantiomers was achieved in less than 10 min using 100 mM phosphate solution as background electrolyte and pH 3.5, at the presence of 3.0 mM HDAS‐β‐CD and at 20°C. In addition, this analytical condition proved to be useful for the enantioseparation of a number of other β‐blocking agents such as alprenolol, atenolol, bisoprolol, celiprolol, metipranolol, oxprenolol, and sotalol. For determing talinolol, the method could be validated in terms of precision, accuracy and linearity, and was found to be suitable in determination of talinolol enantiomers in highly diluted samples obtained from in vitro experiments.
Comparison of charged cyclodextrin derivatives for the chiral separation of atropisomeric polychlorinated biphenyls by capillary electrophoresis
Authors: García‐Ruiz Carmen , Crego Antonio L. , Marina M. Luisa 
Published: July 2003

AbstractCharged cyclodextrin (CD) derivatives were used as chiral selectors in electrokinetic chromatography (EKC) for the chiral separation of highly hydrophobic neutral racemates such as atropisomeric polychlorinated biphenyls (PCBs). β‐CD‐phosphated, β‐CD sulfated, succinylated‐γ‐CD (Succ‐γ‐CD) and succinylated‐β‐CD (Succ‐β‐CD) were used as anionic CDs. As cationic CD, 6‐monodeoxy‐6‐monoamino‐β‐CD (β‐CD‐NH2) was tested for the first time in order to separate PCBs. From the different CD derivatives employed, the best separations were obtained with the cationic CD derivative. Thus, the use of β‐CD‐NH2 in phosphate buffer at pH 2.0 containing urea allowed the chiral recognition of eleven PCBs (45, 84, 88, 91, 95, 131, 136, 144, 149, 176, and 197). In this case, the addition of 2 M urea to the buffer solution was crucial to achieve the chiral separation of PCBs. The addition of acetonitrile to 10 mM phosphate buffer (pH 2.0) with 30 mM β‐CD‐NH2 and 2 M urea improved considerably the chiral resolution obtained for PCBs 91, 95, 136, 144, 149, and 197 although an increase in the analysis time was also observed. All the results obtained were compared with those previously obtained with the dual CD system carboxymethyl‐γ‐CD/β‐CD.
Influence of peak measurement parameters on the quality of chiral electrophoretic separations
Authors: Perrin Catherine , Fabre Huguette , Massart D. Luc , Vander Heyden Yvan 
Published: July 2003

AbstractThe effect of nine peak measurement/analysis parameters on chiral capillary electrophoresis (CE), followed by UV detection, was studied. The parameters pertained UV‐detection (detection wavelength, reference wavelength, and wavelength bandwidths), signal processing (data acquisition rate, type and amount of filtering) and peak detection (detection threshold and peak width). The influence of these factors on the chiral separation of dimethindene enantiomers was studied at two different concentrations (i.e., at high and low signal‐to‐noise (S/N) ratio) by the means of experimental designs. The electropherogram characteristics considered were the resolution between the two enantiomers, the peak areas, and the S/N ratio. A D‐optimal design was first used as screening design to identify the most critical parameters. Afterwards, a modelling of the different responses as a function of these critical parameters was performed based on the results of a face‐centered central composite design. The results showed that the signal‐processing parameters should be carefully selected when developing a CE separation since very important variations in the separation, the S/N ratio and the peak area of the substances can occur by setting these parameters at different levels. The detection wavelength should also be carefully chosen for optimal peak area measurement. The role of these parameters becomes more important with decreasing concentration of the analytes (i.e., low S/N ratio). This study showed that the peak measurement/analysis parameters should be optimized as the chemical and physical parameters of a method. They also should always be well specified in order to allow a good transfer of a method from one instrument to another.
Chiral characterization of deprenyl‐N‐oxide and other deprenyl metabolites by capillary electrophoresis using a dual cyclodextrin system in rat urine
Authors: Tábi Tamás , Magyar Kálmán , Szökő Éva 
Published: July 2003

AbstractA chiral capillary electrophoresis method has been developed for the simultaneous separation of the enantiomers of deprenyl and eight of its metabolites, among them the recently described metabolite deprenyl‐N‐oxide. Although heptakis‐(2,6‐di‐O‐methyl)‐β‐cyclodextrin (DIMEB) was suitable for the enantioresolution of deprenyl and its dealkylated derivatives, the enantiomers of deprenyl‐N‐oxide were just partly resolved. Carboxymethyl‐β‐cyclodextrin (CMBCD) in as low as 2 mM concentration was capable of the enantiomer separation of all the nine examined compounds, however co‐migration of 1R,2S‐(−)‐norephedrine and 1R,2R‐(−)‐pseudoephedrine, as well as 1S,2R‐(+)‐ephedrine and R‐(−)‐amphetamine was observed. This problem could be overcome by the use of a dual cyclodextrin system containing 4 mM DIMEB in addition to 2 mM CMBCD; simultaneous separation of all the compounds could be achieved. The optimized method was used for the analysis of rat urine samples after 10 days of treatment of animals with either R‐(−)‐ or S‐(+)‐deprenyl. The stereospecific biotransformation of both deprenyl enantiomers was confirmed, and the stereoselectivity of N‐oxide formation was demonstrated.