bluuebunny/crossref_metadata_2025_split huggingface dataset:
Number and dendritic morphology of retinal ganglion cells that survived after axotomy in adult cats
Authors: Watanabe Masami , Sawai Hajime , Fukuda Yutaka 
Published: January 2005

AbstractRetinal ganglion cells (RGCs) of adult cats were labeled by injection of diI into the proximal stump of completely transected optic nerves. Approximately 2% to 5% of the RGC population appeared viable 2 months after these axotomies, based on diI retention. The morphological type and dendritic arbor of these surviving RGCs were examined after intracellular injections of Lucifer Yellow into diI‐labeled RGCs. Postaxotomy survival rate was much higher for α‐like cells than for β‐like cells. However, in one of four retinas examined, a large number of RGCs seemed to survive axotomy, and among these, β cells survived at an unusually high rate. Dendritic arbors of surviving RGCs were also examined after intracellular injection of horseradish peroxidase. Some dendrites of these RGCs lacked branches and were thin in caliber. Other dendrites displayed many spiny processes and bulbous swellings. Essentially, these results confirm the previous suggestion that α cells survive axotomy longer than β cells. The ability of α cells to regenerate axons may thus be attributable to their relatively high resistance to axotomy. The atypical dendritic profiles seen after optic nerve transection may reflect either degeneration or regrowth of dendrites. © 1995 John Wiley & Sons, Inc.
Using reflexive behaviors of the medicinal leech to study information processing
Authors: Kristan William B. , Lockery Shawn R. , Lewis John E. 
Published: January 2005

AbstractThe interneuronal network that produces local bending in the leech is distributed, in the sense that most of the interneurons involved are activated in all forms of local bending, even those in which their outputs would produce inappropriate movements. Such networks have been found to control a number of different behaviors in a variety of animals. This article reviews three issues: the physiological and modeling observations that led to the conclusion that local bending in leeches is controlled by a distributed system; what distributed processing means for this and other behaviors; and why the leech interneuronal network may have evolved to be distributed in the first place. © 1995 John Wiley & Sons, Inc.
Diversity and modulation of ionic conductances in leech neurons
Authors: Kleinhaus Anna L. , Angstadt James D. 
Published: January 2005

AbstractA complete understanding of animal behavior at the cellular level requires detailed information on the intrinsic biophysical properties of neurons, muscles, and the synaptic connections they make. In the past 10 to 15 years, electrophysiological studies of leech neurons have revealed a diverse array of voltage‐gated ionic conductances distinguished by their pharmacological sensitivity to classic ion channel blockers. Voltage‐clamp studies have provided new information about the kinetics and voltage‐dependence of Na+ conductances, several K+ currents, including IA, IK and IK(Ca.)' and high‐ and low‐voltage‐gated Ca2+ conductances. These studies showed that the action potentials of most leech neurons result from the usual sequence of permeability changes to Na+, K+, and Ca2+ ions. They also added insight as to the role played by particular combinations of conductances in providing individual neurons with electrical properties appropriate for the particular information they encode. Evidence is accumulating on the modulatory actions of endogenous neurotransmitters such as FMRFamide, serotonin, and octopamine on motor behaviors in the animal. Parallel studies suggest that changes in behavior can be explained, at least in part, by the alteration of firing patterns of selected neurons and muscles resulting form modulation of multiple ion conductances. This makes the leech exceptionally attractive for neuroethological studies because it is one of the simplest organisms in which the methods of psychology and neurobiology can be combined. Information gathered from this animal will therefore increase our understanding regarding general principles underlying the cellular basis of behavior. © 1995 John Wiley & Sons, Inc.
Lack of a synergistic effect between estradiol and dihydrotestosterone in the masculinization of the zebra finch song system
Authors: Jacobs Erin C. , Grisham William , Arnold Arthur P. 
Published: January 2005

AbstractPrevious studies have suggested that both major active metabolites of testosterone, estradiol (E2) and dihydrotestosterone (DHT), are needed for complete masculinization of the brain regions that control song in passerine birds. However, DHT treatment of hatchling female zebra finches has only small masculinizing effects on the song system. To assess whether E2 and DHT have a synergistic effect on the masculinization of the zebra finch song system, female zebra finches were given Silastic implants of E2 on the day of hatching (day 1) either without any additional hormone treatment or in combination with DHT on days 1, 14, or 70. At 105 to 110 days of age, we measured the volumes of Area X, higher vocal center (HVC), robust nucleus of the archistriatum (RA), soma sizes in HVC, RA, and the lateral magnocellular nucleus of the neostriatum (lMAN), and neuron density and number in RA. E2 masculinized all of the measures in the song system with the exception of the number of neurons in RA. DHT did not synergize with E2 to produce any additional masculinization of the attributes measured. These data demonstrate that the combination of E2 and DHT did not result in the complete masculinization of the song control nuclei and argue against the importance of androgen in sexual differentiation of the song system. © 1995 John Wiley & Sons, Inc.
Seasonal changes in song nuclei and song behavior in Gambel's white‐crowned sparrows
Authors: Troy Smith G. , Brenowitz Eliot A. , Wingfield John C. , Baptista Luis F. 
Published: January 2005

AbstractIn males of several songbird species, the morphology of forebrain nuclei that control song changes seasonally. The only seasonally breeding songbird in which seasonal changes in the structure of song control nuclei have been reported not to occur is the nonmigratory Nuttall's subspecies of white‐crowned sparrow. In the present study, we manipulated photoperiod and plasma testosterone concentrations in captive male white‐crowned sparrows of the migratory Gambel's subspeices. Males exposed to photoperiods and plasma testosterone concentrations typical of those experienced by wild breeding males had larger song control nuclei than males held on a winter photoperiod. We also found seasonal change in stereotypy of spectral and temporal parameters of song in wild Gambel's white‐crowned sparrows. We hypothesize that seasonal changes in song control nuclei may correlate with seasonal changes in song stereotypy. © 1995 John Wiley & Sons, Inc.
Fate of the anterior neural ridge and the morphogenesis of the xenopus forebrain
Authors: Eagleson Gerald , Ferreiro Beatriz , Harris William A. 
Published: January 2005

AbstractThe fate of the anterior neural ridge was studied by following the relative movements of simultaneous spot applications of DiI and DiO from stage 15 through stage 45. These dye movements were mapped onto the neuroepithelium of the developing brain whose shape was gleaned from whole‐mount in situs to neural cell adhesion molecule and dissections of the developing nervous system. The result is a model of the cell movements that drive the morphogenesis of the forebrain. The midanterior ridge moves inside and drops down along the most anterior wall of the neural tube. It then pushes forward a bit, rotates ventrally during forebrain flexing, and gives rise to the chiasmatic ridge and anterior hypothalamus. The midanterior plate drops, forming the floor of the forebrain ventricle, and, keeping its place behind the ridge, it gives rise to the posterior hypothalamus or infundibulum. The midlateral anterior ridge slides into the lateral anterior wall of the neural tube and stretches laterally into the optic stalk and retina, and then rotates into a ventral position. The lateral anterior ridge converges to the most anterior part of the dorsal midline during neural tube closure, then rotates anteriorly, and gives rise to telencephalic structures. Whole‐mount bromodeoxyuridine labeling at these stages showed that cell division is widespread and relatively uniform throughout the brain during the late neurula and early tailbud stages, but that during late tailbud stages cell division becomes restricted to specific proliferative zones. We conclude that the early morphogenesis of the brain is carried out largely by choreographed cell movements and that later morphogenesis depends on spatially restricted patterns of cell division. © 1995 John Wiley & Sons, Inc.
Human schwann cells in vitro. II. Myelination of sensory axons following extensive purification and heregulin‐induced expansion
Authors: Morrissey T. K. , Kleitman N. , Bunge R. P. 
Published: January 2005

AbstractCo‐culture conditions are well established in which Schwann cells (SCs) derived from immature or adult rats proliferate and form myelin in response to contact with sensory axons. In a companion article, we report that populations of adult‐derived human Schwann cells (HASCs) fail to function under these co‐culture conditions. Furthermore, we report progressive atrophy of neurons in co‐cultures containing populations of either human fibroblasts. Two factors that might account for the insufficiency of the co‐culture system to support HASC differentiation are the failure of many HASCs to proliferate and the influence of contaminating fibroblasts. To minimize fibroblast contamination of neuron‐HASC co‐cultures, we used fluorescence‐activated cell sorting to highly purify HASC populations (to more than 99.8%). To stimulate expansion of the HASC population, a mitogenic mixture of heregulin (HRGβ1 amino acid residues 177‐244; 10 nM), cholera toxin (100 ng/mL), and forskolin (1 μM) was used. When these purified and expanded HASCs were co‐cultured with embryo‐derived rat sensory neurons, neuronal shrinkage did not occur and after 4 to 6 weeks some myelin segments were seen in living co‐cultures. This myelin was positively identified as human by immunostaining with a monoclonal antibody specific to the human peripheral myelin protein P0 (antibody 592). Although this is the first reported observation of myelination by HASCs in tissue culture, it should be noted that myelination occurred more slowly and in much less abundance than in comparable cultures containing adult rat‐derived SCs. We anticipate that further refinements of the HASC co‐culture system that enhance myelin formation will provide insights into important aspects of human SC biology and provide new opportunities for studies of human peripheral neuropathies. © 1995 John Wiley & Sons, Inc.
Development of an identified serotonergic neuron in the antennal lobe of the moth and effects of reduction in serotonin during construction of olfactory glomeruli
Authors: Oland Lynne A. , Kirschenbaum Sheila R. , Pott Wendy M. , Mercer Alison R. , Tolbert Leslie P. 
Published: January 2005

AbstractEach olfactory (antennal) lobe of the moth Manduca sexta contains a single serotonin (5‐HT) immunoreactive neuron whose processes form tufted arbors in the olfactory glomeruli. To extend our present understanding of the intercellular interactions involved in glomerulus development to the level of an individual, identified antennal lobe neuron, we first studied the morphological development of the 5‐HT neuron in the presence and absence of receptor axons. Development of the neuron's glomerular tufts depends, as it does in the case of other multiglomerular neurons, on the presence of receptor axons. Processes of the 5‐HT neuron are excluded from the region in which the initial steps of glomerulus construction occur and thus cannot provide a physical scaffolding on which the array of glomeruli is organized. Because the neuron's processes are present in the antennal lobe neuropil throughout postembryonic development, 5‐HT could provide signals that influence the pattern of development in the lobe. By surgically producing 5‐HT‐depleted antennal lobes, we also tested the importance of 5‐HT in the construction of olfactory glomeruli. Even in the apparent absence of 5‐HT, the glomerular array initiated by the receptor axons was histologically normal, glial cells migrated to form glomerular borders, and receptor axons formed terminal branches in their normal region within each glomerulus. In some cases, 5‐HT‐immunoreactive processes from abnormal sources entered the lobe and formed the tufted intraglomerular branches typical of most antennal lobe neurons, suggesting that local cues strongly influence the branching patterns of developing antennal lobe neurons. © 1995 John Wiley & Sons, Inc.
Establishment of neuronal connectivity during development of the Drosophila larval visual system
Authors: Campos Ana Regina , Lee Kevin J. , Steller Hermann 
Published: January 2005

AbstractWe used confocal microscopy in conjunction with specific antibodies and enhancer trap strains to investigate the development of specific neuronal connections in a simple model system, the larval visual system of Drosophila. We find that the establishment of axonal projections from the larval photoreceptor neurons to their central nervous system targets involves a series of discrete steps. During embryogenesis, the larval optic nerve contacts several different cell types, including optic lobe pioneer (OLP) neurons and a number of glial cells. We demonstrate that OLP neurons are present and project normally in glass (gl) mutant embryos in which the larval optic nerve fails to develop, suggesting that they do not depend on interactions with the larval optic nerve for differentiation and proper axonal projection. The OLPs fail to differentiate properly in disconnected (disco) mutant embryos, where appropriate connections between the larval optic nerve and its targets in the brain are not formed. The disco gene is expressed in the OLPs and may therefore act autonomously to direct the differentiation of these cells. Taken together, our results suggest that the OLPs act as an intermediate target required for the establishment of normal optic nerve projection and connectivity. © 1995 John Wiley & Sons, Inc.
Characterization of resol resins modified by the addition of PVC plastisols
Authors: Manfredi LB , Jiménez A , Vázquez A 
Published: January 2005

AbstractPlastisols, which are a blend of poly(vinyl chloride) resin and a plasticizer (DEHP), were used as a toughening agent of a resol resin in order to improve the mechanical properties. It was not possible to formulate resol blends by adding more than 10 % of plastisol owing to a lack of apparent homogeneity in the systems, which also showed many air bubbles. The relationship between dynamic mechanical, mechanical and thermal properties and the amount of plastisol added was studied. It was determined from the infrared spectroscopy and dynamic mechanical results that the resol–plastisol blends seem to be formed by a reaction between the phenol and PVC giving a higher crosslinked structure. An improvement in the thermal resistance of the blends at lower temperatures was observed with an increase in the percentage of plastisol. Flexural analysis showed the elastic behaviour of the systems. However, it was not possible to observe the effect of the plasticizer (DEHP) owing to the low quantity of plastisol that was added to the resol. Copyright © 2004 Society of Chemical Industry
Conducting composites of polythiophene and polyfuran with acetylene black
Authors: Ballav Nirmalya , Biswas Mukul 
Published: January 2005

AbstractConducting composites of polythiophene (PTP) and polyfuran (PF) with acetylene black (AB) were prepared via chemical oxidative polymerization of thiophene and furan in a suspension of AB in CHCl3 at room temperature using anhydrous FeCl3 as the oxidant. Formation of PTP and PF and their subsequent incorporation in PTP–AB and PF–AB composite systems were confirmed by FTIR analysis. Scanning electron microscope analysis showed the presence of compact clusters of particles in both composites. Transmission electron micrographs of PTP–AB and PF–AB composites showed formation of globular polymer encapsulated AB particles with average diameters of the order of ∼100 nm in both systems. Thermogravimetric analysis revealed that the overall thermal stability varied in the order: AB > PTP–AB > PTP and AB > PF–AB > PF. DC conductivity values for the PTP–AB and PF–AB composites were of the order of 10−2 and 10−3 S cm−1, respectively. Copyright © 2004 Society of Chemical Industry
Differential protein expression by Porphyromonas gingivalis in response to secreted epithelial cell components
Authors: Zhang Yi , Wang Tiansong , Chen Weibin , Yilmaz Özlem , Park Yoonsuk , Jung Il‐Young , Hackett Murray , Lamont Richard J. 
Published: January 2005

AbstractThe human oral pathogen Porphyromonas gingivalis colonizes the gingival crevice and invades gingival epithelial cells. Multidimensional capillary high‐performance liquid chromatography coupled with tandem mass spectrometry and two‐dimensional gel electrophoresis were used to analyze the proteome of P. gingivalis as it adapts to a set of experimental conditions designed to reflect important features of an epithelial cell environment. 1014 proteins (46% of the total theoretical proteome) were identified in four independent analyses; 479 of these proteins showed evidence of differential expression after exposure of P. gingivalis to either conditioned epithelial cell growth medium or control conditions: i.e., they were only detected under one set of conditions. Moreover, 276 genes annotated as hypothetical were found to encode expressed proteins. Among the proteins up‐regulated in the presence of epithelial cell components were a homolog of the internalin proteins of Listeria monocytogenes and subunits of the ATP‐dependent Clp protease complex. Insertional inactivation of clpP, encoding the Clp proteolytic subunit, resulted in approximately a 50% reduction in invasion of P. gingivalis. These results suggest that adaptation to an epithelial cell environment induces a major shift in the expressed proteome of the organism. Furthermore, ClpP, that is up‐regulated in this environment, is required for optimal invasive activity of P. gingivalis.
Polymerization of styrene with tetramethylthiuram disulfide as an initiator in the presence of 2,2,6,6‐tetramethyl‐1‐piperidinyloxy
Authors: Xu Wenjian , Zhu Xiulin , Cheng Zhenping , Chen Gaojian , Zhu Jian 
Published: January 2005

AbstractThe bulk polymerization of styrene was investigated with tetramethylthiuram disulfide (TMTD) as an initiator in the presence of 2,2,6,6‐tetramethyl‐1‐piperidinyloxy (TEMPO) at 123 °C. The polymerization proceeded in a controlled/living way; that is, the polymerization rate was first‐order with respect to the monomer concentration, and the molecular weight increased linearly with conversion. The molecular weights of the polymers obtained were close to the theoretical values, and the molecular weight distributions were relatively low (weight‐average molecular weight/number‐average molecular weight = 1.1–1.3). The rate of polymerization with TMTD as an initiator was faster than that with benzoyl peroxide, and the rate was independent of the initial concentration of TMTD in the presence of TEMPO. The obtained polystyrene was functionalized with ultraviolet‐light‐sensitive SC(S)N(CH3)2 groups, which was characterized with 1H NMR spectroscopy. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 543–551, 2005
Enantiomer (+)physostigmine prevents organophosphate‐induced subjunctional damage at the neuromuscular synapse by a mechanism not related to cholinesterase carbamylation
Authors: Kawabuchi M. , Boyne A. F. , Deshpande S. S. , Cintra W. M. , Brossi A. , Albuquerque E. X. 
Published: January 2005

AbstractThe natural alkaloid (‐)PHY is a reversible anticholinesterase carbamate, but in contrast, its optical isomer (+)PHY, is a very weak anticholinesterase. We have shown that treatment of rats with atropine and (‐)PHY prior to injections of a lethal dose of the irreversible organophosphate sarin (0.13 mg/kg) not only protected 100% of the animals from lethality but also reduced the size of the subneural lesions of the nicotinic synapses of skeletal muscle. Similar protection against lethality is provided by pretreatment with (+)PHY. At the concentration used (0.3 mg/kg), there was no detectable inhibition of AChE activity. We have examined the protection afforded by (+)PHY or (‐)PHY against lethality and myopathy due to organophosphate agents such as sarin. The major alterations in the soleus motor endplates 1 hr after drug treatment were as follows: (1) A single sublethal dose of sarin (0.08 mg/kg) produced enlarged, blistered, and severely disrupted subjunctional regions, with muscle damage extendig beyond the endplate to include myofiber necrosis and subsequent phagocytosis; (2) (+)PHY (0.3 mg/kg) produced no obvious damage in the postjunctional region; (3) (‐)PHY (0.1 mg/kg) had a selective effect in inducing irregularities of the subjunctional sarcomere band patterns without any gross vacuolization; (4) light microscopic data indicated that the combination of atropine and (+)PHY, or of atropine and (‐)PHY (0.1 mg/kg), 30 min prior to a lethal dose of sarin, offered dramatic reduction in the average dimension of lesions. Lesions were detectable in most endplates but recognizable changes were markedly less severe than those seen in sarin myopathy. Few instances of extensive muscle damage and myofiber necrosis were visible.In each of the 3 experimental groups examined, the extrajunctional myopathy was reversible with substantial recovery being observed on days 5 and 10 after drug treatment.In addition to its anticholinesterase activity, (‐)PHY is also a powerful ion channel blocker of the nicotinic acetylcholine receptor. As for (+)PHY, its protective effect almost certainly does not depend at inhibition of acetylcholinesterase, but as with (‐)PHY, it my depend on a direct blockade at the nicotinic‐acetylcholine receptor and its ion channel.