bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of neuronal activity in upregulating GFAP mRNA levels after electrolytic lesions of the entorhinal cortex
Authors: Kelley Melinda S. , Steward Oswald 
Published: April 2003

AbstractThis study evaluates whether the rapid transient increases in glial fibrillary acidic protein (GFAP) mRNA in the hippocampus after electrolytic lesions of the entorhinal cortex (EC) are triggered by lesion‐induced changes in hippocampal neuronal activity (either the decreases that result from loss of afferent drive or transient increases that occur during lesion production). To evaluate the role of activity, we carried out four experiments: (1) tetrodotoxin (TTX) was injected into the EC to mimic the decreases in afferent drive that occur after lesion; (2) TTX was injected into the EC or hippocampus before producing electrolytic lesions to block any abnormal activity induced during lesion production; (3) the EC was destroyed by aspiration, thus creating a lesion comparable in size to the electrolytic lesion, without passing direct current; (4) seizures were elicited by stimulating the EC of anesthetized rats, to examine whether electrographic seizures alone can induce the same type of increases in GFAP mRNA as lesions. Our results demonstrated that: (1) TTX injections into the EC did not induce the same increases in GFAP mRNA levels that occurred after EC lesions; (2) animals that received TTX injections into the EC prior to lesions exhibited increases in hippocampal GFAP mRNA that were nearly as great as following EC lesions alone; (3) aspiration lesions of the EC resulted in increases in GFAP mRNA that were comparable to those observed after electrolytic lesions (4) seizure‐inducing stimulation of the EC resulted in 2‐fold increases in GFAP mRNA in the hippocampus 24 hr after stimulation rather than the 5–13‐fold increases observed after lesions. These results suggest that lesion‐induced changes in hippocampal neuronal activity are not solely responsible for inducing the rapid transient increases in GFAP mRNA levels in the hippocampus ipsilateral to EC lesions.
Reactive astroglia‐neuron relationships in the human cerebellar cortex: A quantitative, morphological and immunocytochemical study in Creutzfeldt‐Jakob disease
Authors: Lafarga M. , Berciano M.T. , Saurez I. , Andres M.A. , Berciano J. 
Published: April 2003

AbstractIn order to investigate the role of neuron‐glia interactions in the response of astroglial to a non‐invasive cerebellar cortex injury, we have used two cases of the ataxic form of Creutzfeldt‐Jakob disease (CJD) with distinct neuronal loss and diffuse astrogliosis. The quantitative study showed no changes in cell density of either Purkinje or Bergmann glial cells in CJ‐1, whereas in the more affected CJ‐2 a loss of Purkinje cells and an increase of Bergmann glial cells was found. The granular layer in both CJD cases showed a similar loss of granule cells (about 60%) in parallel with the significant increase in GFAP+ reactive astrocytes. GFAP immunostaining revealed greater reactivity of Bergmann glia in CJ‐2 than in CJ‐1, as indicated by the thicker glial processes and the higher optical density. Granular layer reactive astrocytes were regularly spaced. In both CJD cases there was strict preservation of the spatial arrangement of all astroglial subtypes—Fañanas cells, Bergmann glia and granular layer astrocytes. Reactive Fañanas and Bergmann glial cells and microglia/macrophages expressed vimentin, while only a few vimentin+ reactive astrocytes were detected in the granular layer. Karyometric analysis showed that the increase in nuclear volume in reactive astrloglia was directly related with the level of glial hypertrophy. The number of nucleoli per nuclear section was constant in astroglial cells of human controls and CJD, suggesting an absence of polyploidy in reactive astroglia. Ultrastructural analysis revealed junctional complexes formed by the association of macula adherens and gap junctions. In the molecular layer numerous vacant dendritic spines were ensheathed by lamellar processes of reactive Bergmann glia. Our results suggest that quantitative (neuron/astroglia ratio) and qualitative changes in the interaction of neurons with their region‐specific astroglial partners play a central role in the astroglial response pattern to the pathogenic agent of CJD.
Endogenous stimulation of lipid peroxidation in brain increases proteolytic‐inactivation of mitochondrial monoamine oxidases
Authors: Medvedev Alexei E. , Gorkin Vladimir Z. 
Published: April 2003

AbstractStimulation of lipid peroxidation in vivo (in experimental epilepsy and closed cranio‐cerebral injury, as models for endogenous stimulation of lipid peroxidation) affects catalytic activity, substrate specificity of mitochondrial monoamine oxidases and increases their susceptibility to trypsinolysis. It is suggested that increased susceptibility to trypsinolysis reflects an appearance of new hydrophilic site(s) in monoamine oxidase molecules which may be responsible for an involvement of the modified enzymes in the deamination of other important nitrogenous compounds (such as γ‐aminobutyric acid) with subsequent impairment of a ratio between inhibition and excitation processes in the brain.
Development of human lateral geniculate nucleus: An electron microscopic study
Authors: Khan Aijaz Ahmed , Wadhwa Shashi , Bijlani Veena 
Published: April 2003

AbstractA qualitative and quantitative ultrastructural study has been carried out on lateral geniculate nuclei (LGN) of 21 human fetuses ranging in gestational age from 13–14 to 34–35 weeks. At the early age period of 13–15 weeks, LGN is characterized by immature cells with indented nuclei possessing multiple nucleoli and by a sparse neuropil. During the subsequent age periods studied progressive maturational changes lead to neurons having round nuclei with a single nucleolus and well‐developed cytoplasmic organelles as well as to an elaborate neuropil. Synaptic contacts which are seen for the first time at the age of 13–14 weeks are of retinogeniculate type. They show features of immature synapses and are located mainly on the juxtasomatic parts of dendrites. With increasing gestational age, the synapses increase in size, maturity, types and complexity; an acquisition of complex synaptic arrangement (triad) occurs by 20–21 weeks. Excitatory synapses appear earlier than do the inhibitory ones. Formation of retinogeniculate contacts precedes that of the corticogeniculate type.The synaptic density and total synapse number show a progressive increase with increasing gestational age. The age period of 15–20 weeks of gestation is marked by presence of organelles suggestive of a high rate of metabolic activity, significant increase in synaptogenesis, presence of transient contacts on soma and large number of free postsynaptic membrane densities (PSD). The period thereby represents a critical period in the development of synapses in LGN. The numerical values obtained by the age of 34–35 weeks are still low as compared to the values reported for other areas of brain.
Changes in expression of the low affinity receptor for neurotrophins, p75NGFR, in the regenerating olfactory system
Authors: Turner Christopher P. , Perez‐Polo J.Regino 
Published: April 2003

AbstractWe have disrupted the integrity of the rat olfactory neuroepithelium using intranasally applied TX‐100, a procedure known to reversibly eliminate the sensory neuron input from the neuroepithelium to the olfactory bulb [Margolis et al. (1974) Denervation in the primary olfactory pathway of mice: biochemical and morphological effects. Brain Res.81, 469–483]. One week after TX‐100 exposure, we observed a disruption of the pseudo‐stratified organization of the neuroepithelium which was accompanied by a 60% reduction in neuroepithelial width, compared to saline‐treated controls. Full recovery of the neuroepithelium was not observed until 16 weeks post‐lesion. During this post‐lesion period, we monitored the expression of the low affinity receptor for neurotrophins, p75NGFR, in the olfactory bulb of saline‐ and TX‐100‐treated animals, using the monoclonal antibody, MAb192. In saline‐treated animals, p75NGFR‐immunoreactivity (p75NGFR‐ir) was localized to individual glomeruli in the olfactory bulb, with little or undetectable p75NGFR‐ir in the olfactory nerve layer. We have previously reported that pre‐lesioned levels of p75NGFR‐ir in the glomerular layer were dramatically reduced while an induction of p75NGFR‐ir was observed in the olfactory nerve layer, one and two weeks after intranasal exposure to TX‐100 [Turner & Perez‐Polo (1992) Regulation of the low affinity receptor for nerve growth factor, p75NGFR, in the olfactory system of neonatal and adult rat. Int. J. Devl Neurosci.10, 343–359]. In this paper, we demonstrate that this previously reported reduction in glomerular p75NGFR‐ir took 16 weeks to fully recover and was, thus, coincident with the post‐lesion recovery of the neuroepithelium. In the olfactory nerve layer, the return of p75NGFR‐ir to pre‐lesioned levels took only four weeks. No changes in neuroepithelial width and integrity or alterations in p75NGFR‐ir in the olfactory bulb were observed in saline‐treated animals. Thus, the TX‐100‐induced removal of the peripheral input to the olfactory bulb resulted in a reversible change in expression of p75NGFR‐ir in the bulb. We believe that these changes are a reflection of the regenerative capacity of the olfactory system.
Neuroprotective effect ofN‐methyl‐d‐aspartate non‐competitive antagonists (arylcyclohexylamine derivatives) on human cultured spinal cord cells
Authors: Levallois C. , Calvet M.C. , Petite D. , Kamenka J.M. 
Published: April 2003

AbstractThe non‐competitive N‐methyl‐d‐aspartate antagonist cis‐Pip/Me 1‐[1‐(2‐thienyl)‐2‐methyl‐cyclohexyl] piperidine (GK11) either in racemic(±) or (−) enantiomeric form has been investigated on survival of human fetal spinal cord cells in culture. The treated cultured cells were processed for immunocytochemical detection of GABA at different time intervals ranging from 3 to 27 weeks. The number of GABA‐stained cells was found to be greater in the treated cultures than in the control ones. The qualitative and quantitative morphological features of both control and treated cells were analysed by computer‐assisted methods which allowed us to individualize three different populations: (1) all control and treated small neuritic field neurons, (2) young control and old treated large neuritic field neurons and (3) old control neurons with large neuritic fields.
Subcellular location and differential antibody specificity of arginase in tissue culture and whole animals
Authors: Spector Elaine B. , Jenkinson Christopher P. , Grigor Murray R. , Kern Rita M. , Cederbaum Stephen D. 
Published: April 2003

AbstractStudies in man and other mammals have demonstrated the existence of two forms of arginase, a cytoplasmic form located primarily in liver and a mitochondrial form expressed in lesser amounts in a larger number of organs, but especially kidney. They appear to be encoded in different gene loci. Using a colloidal silica gradient separation technique, we have now located arginase in H4 cells, a rat hepatoma‐derived line, to the cytoplasm and the arginase in human embryonic kidney‐derived line, to the mitochondrion. Antibody prepared against A1 precipitates all the arginase from liver, 50% from kidney and none of the activity from human embryonic kidney (HEK) cells. An antibody prepared against partially purified All, by contrast, precipitates >90% of arginase activity from HEK cells, half from kidney and virtually none from H4 cells or rat liver.
Approaches to the factory of the future. An empirical taxonomy
Authors: Boyer Kenneth K. , Ward Peter T. , Leong G.Keong 
Published: April 2003

AbstractAn empirical analysis of the patterns in which companies invest in advanced manufacturing technologies (AMTs) such as computer‐aided design, computer‐aided manufacturing, and flexible manufacturing systems is presented. Data for this analysis are gathered from 202 manufacturing plants chosen from industries generally considered to have relatively high investments in technology.Three general types of AMTs are identified from the literature: design, manufacturing, and administrative. Multiple item scales are developed to measure each type of AMT. These scales are shown to be reliable instruments, and are used to develop an empirical taxonomy which validates existing conceptual typologies of AMTs. A cluster analysis reveals four distinct groups of companies with respect to their approaches toward investing in AMTs. TRADITIONALISTS do not invest heavily in any of the three types of AMTs. GENERALISTS have moderate investments in each technology type. HIGH INVESTORS have the highest investment in each of the three technology types. The most interesting group may well be the DESIGNERS, which have low investments for manufacturing and administrative AMTs, but have the second highest investment in design‐related AMTs.An analysis of the four technology groups reveals that while plants do differ in terms of plant size and integration, they do not differ significantly in terms of industry membership or performance. This suggests that successful firms can be found in each of the groups and that good strategies may be found that are consistent with each of these approaches. Therefore, the taxonomy is fairly robust, and further research must analyze companies within these groupings in order to identify the contingencies or other factors that may act in conjunction with technology to separate high and low performing firms. The data from our study clearly suggest that investments in technology alone are not a causal factor for performance improvement.
Corporate governance and market valuation of capital and R&D investments
Authors: Chung Kee H. , Wright Peter , Kedia Ben 
Published: April 2003

AbstractIn this study, we examine how corporate governance structure affects market valuation of capital and R&D investments. We employ three empirical proxies of corporate governance—analyst following, board composition, and institutional holdings, and study whether market valuation of corporate investments varies with governance structure. Our results show that the market valuation of the firm's capital and R&D investments depends critically on analyst following and board composition, but not on institutional holdings.
Safety and efficacy of low-energy cardioversion of 500 patients using two different techniques
Authors: Andraghetti A. , Scalese M. 
Published: April 2003

Abstract

Aim
To present some safety and efficacy issues of low-energy internal cardioversion of chronic atrial fibrillation from 500 consecutive procedures performed with two different techniques, using either two single-coil catheters, or a single twin-coil catheter.

Methods and Results
Low-energy internal cardioversion was carried out in 368 patients by means of two defibrillation catheters: the former was positioned in the right atrium and the latter either in the left pulmonary artery (212 patients), or in the distal coronary sinus (156 patients). In the remaining 132 patients, a single twin-coil catheter was positioned with the distal coil either in the pulmonary artery (75 patients) or in the coronary sinus (57 patients), while the proximal coil was in the right atrium. The external defibrillator delivered truncated biphasic shocks (6/6 ms, tilt 50%), with a voltage of 10–400 V. In 283 patients (57%) external cardioversion had been unsuccessfully tried before low-energy internal cardioversion. After a total of 1118 shocks, the overall success rate was 92·2% (91·3% with two catheters and 94·7% with the single catheter); the success rate was 93·4 and 91·3% with the coronary sinus and the pulmonary artery approach, respectively. The mean energy used was 6·5±3·4 J (voltage: 320±45 V); no difference was found between the twin catheter (6·3±3·1 J) and the single catheter approach (6·9±3·7 J), while the coronary sinus configuration required a significantly lower energy than the pulmonary artery configuration (5·6±2·9 vs 7·2±3·8 J, P<0·05). The duration of the current atrial fibrillation episode was the only clinical characteristic statistically different between the 461 successfully cardioverted patients and the 39 failures (295 vs 727 days, P<0·01). No complication was recorded during or after the delivery of the therapy; no procedure had to be terminated because of patient's intolerance.

Conclusions
Low-energy internal cardioversion is a safe and effective procedure for converting chronic atrial fibrillation, confirmed by this large multicentre experience. The newly available twin-coil catheter seems to achieve a slightly better success rate compared with the traditional two-catheter technique, and is associated with the same safety profile.
Contribution of the dimeric state to the thermal stability of the flavoprotein D‐amino acid oxidase
Authors: Pollegioni Loredano , Iametti Stefania , Fessas Dimitrios , Caldinelli Laura , Piubelli Luciano , Barbiroli Alberto , Pilone Mirella S. , Bonomi Francesco 
Published: April 2003

AbstractThe flavoenzyme DAAO from Rhodotorula gracilis, a structural paradigm of the glutathione‐reductase family of flavoproteins, is a stable homodimer with a flavin adenine dinucleotide (FAD) molecule tightly bound to each 40‐kD subunit. In this work, the thermal unfolding of dimeric DAAO was compared with that of two monomeric forms of the same protein: a Δloop mutant, in which 14 residues belonging to a loop connecting strands βF5–βF6 have been deleted, and a monomer obtained by treating the native holoenzyme with 0.5 M NH4SCN. Thiocyanate specifically and reversibly affects monomer association in wild‐type DAAO by acting on hydrophobic residues and on ionic pairs between the βF5–βF6 loop of one monomer and the αI3′ and αI3″ helices of the symmetry‐related monomer. By using circular dichroism spectroscopy, protein and flavin fluorescence, activity assays, and DSC, we demonstrated that thermal unfolding involves (in order of increasing temperatures) loss of tertiary structure, followed by loss of some elements of secondary structure, and by general unfolding of the protein structure that was concomitant to FAD release. Temperature stability of wild‐type DAAO is related to the presence of a dimeric structure that affects the stability of independent structural domains. The monomeric Δloop mutant is thermodynamically less stable than dimeric wild‐type DAAO (with melting temperatures (Tms) of 48°C and 54°C, respectively). The absence of complications ensuing from association equilibria in the mutant Δloop DAAO allowed identification of two energetic domains: a low‐temperature energetic domain related to unfolding of tertiary structure, and a high‐temperature energetic domain related to loss of secondary structure elements and to flavin release.
The Nature of Unnaturalness in Religious Representations: Negation and Concept Combination
Authors: Franks Bradley 
Published: April 2003

AbstractThe cognitive anthropological approach has provided a powerful means of beginning to understand religious representations. I suggest that two extant approaches, despite their general plausibility, may not accurately characterise the detailed nature of those representations. A major source of this inaccuracy lies in the characterisation of negation of ontological properties, which gives rise to broader questions about their ontological determinacy and counter-intuitiveness. I suggest that a more plausible account may be forthcoming by allowing a more complex approach to the representations, deriving from understanding their nature as concept combinations. Such an account also suggests an alternative approach to the role of deference in religious representations. In sum, the empirical and theoretical implications of a more fine-grained analysis of religious representations suggest a vindication of the cognitive anthropology approach to integrating culture and cognition.
Water behavior of poly(vinyl alcohol)/poly(vinylpyrrolidone) interpenetrating polymer network hydrogels
Authors: Kim Seon Jeong , Park Sang Jun , An Kay Hyeok , Kim Nam Gyun , Kim Sun I. 
Published: April 2003

AbstractInterpenetrating polymer network (IPN) hydrogels based on poly(vinyl alcohol) and 1‐vinyl‐2‐pyrrolidone were prepared by radical polymerization with 2,2‐dimethoxy‐2‐phenylacetophenone as a photoinitiator and N,N′‐methylenebisacrylamide as a crosslinker. The IPN hydrogels were analyzed for the sorption behavior of water at 35°C and a relative humidity of 95% with a dynamic vapor sorption system, and water diffusion coefficients were calculated. Differential scanning calorimetry was used to quantitatively determine the amounts of freezing and nonfreezing water. The free‐water contents in the IPN hydrogel samples PV51, PV31, and PV11 were 74.40, 64.03, and 60.48% in pure water, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 24–27, 2003
Adhesion of ethylene–styrene copolymers to polyethylene in microlayers
Authors: Ronesi V. , Cheung Y. W. , Hiltner A. , Baer E. 
Published: April 2003

AbstractThe effects of styrene content, layer thickness, and temperature on the adhesion of ethylene–styrene copolymers (ES) to low‐density polyethylene (LDPE) were examined by measuring the delamination toughness of LDPE/ES microlayers in the T‐peel test. Delamination toughness at ambient temperature decreased with increasing styrene content. A linear correlation between delamination toughness and styrene content in ES was observed. Extrapolation predicted that a copolymer with 72.5 wt % styrene would have no adhesion to LDPE. Experiments on microlayers with relatively thin (8–18 μm) ES layers demonstrated that delamination toughness was proportional to ES layer thickness. In situ observations of the damage zone showed stretching throughout the entire thickness of the ES layer. For higher adhesion systems, ES deformation occurred concurrently with localized stretching and crazing of the LDPE layer at the interface. For two representative systems, the effect of temperature on delamination toughness was studied. Major transitions in delamination toughness and fracture mode were observed at the primary thermal transitions of the ES copolymer. The contribution by stretching of the ES layer to measured delamination toughness was approximated by relating the damage zone to the ES engineering stress–strain curve and was estimated to be about half. The remaining contribution to delamination toughness was assumed to be due to LDPE deformation in the damage zone. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 153–162, 2003