bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alcohol Withdrawal Increases Neuropeptide Y Immunoreactivity in Rat Brain
Authors: Bison Silvia , Crews Fulton 
Published: August 2004

Background: Neuropeptide Y (NPY) is widely expressed in the brain and is known to affect consummatory behaviors including drinking alcohol as well as to play a role in seizures. We investigated the effects of a 4 day binge ethanol treatment model that is known to induce physical dependence and withdrawal seizures to determine the effects of ethanol dependence and withdrawal on NPY expression.Methods: Male Sprague Dawley® rats were treated with ethanol or control nutritionally complete diets by intragastric treatment three times per day for 2 or 4 days with an average daily dose of approximately 8 g/kg ethanol per day. Ethanol‐fed rats treated for 4 days and then withdrawn for 24, 72, and 168 hr also were studied. Brains were perfused and sectioned for immunohistochemistry for NPY, phospho‐cyclic adenosine monophosphate responsive element binding (pCREB), and other proteins.Results: NPY immunoreactivity (NPY‐IR) was found in several brain regions, with the hippocampus and cerebral cortex showing the most pronounced changes. NPY‐IR was reduced by ethanol treatment in hippocampus and cortex, although at 72 hr of withdrawal there was a dramatic increase in NPY‐IR in the hilus of the dentate gyrus and in CA3 and CA2 fields of hippocampus. Ethanol withdrawal seizures occurred around 12 to 24 hr of withdrawal, preceding the changes in NPY‐IR at 72 hr. pCREB immunoreactivity (pCREB‐IR) tended to decrease during ethanol treatment but showed a dramatic increase in dentate gyrus at 72 hr of withdrawal. Parvalbumin immunoreactivity indicated that some of the pCREB‐IR and NPY‐IR were within inhibitory interneuron basket cells of the hippocampal hilus. NPY‐IR returned to control levels by 168 hr of withdrawal.Conclusions: These studies suggest that hippocampal NPY is reduced during the development of ethanol dependence. Ethanol withdrawal seizures precede a dramatic increase in hippocampal NPY‐IR. Previous studies have suggested that NPY in the hippocampus reduces seizure activity and that NPY is induced by seizure activity. Thus, the increase in NPY‐IR at 72 hr of withdrawal after binge ethanol treatment may be protective against prolonged withdrawal seizure activity.
Constructivist learning theory and human capital theory: shifting political and educational frameworks for teachers’ ICT professional development
Authors: Coupal Linda V. 
Published: August 2004

AbstractThis case study discusses the influence of politics on educational technology policies and practices by tracing the effects of a change of governing political parties with differing ideologies and advisory constituencies. It begins by describing a democratic socialist government initiative based on social capital theory and emphasising connections among individuals. The information and communications technology (ICT) initiative is a peer mentorship model of teacher professional development using constructivist learning theory that emphasises activity‐based situated learning processes. The article then describes a shift in the political context with the election of a political party with a market orientation guided by principles of fiscal responsibility and free enterprise. The subsequent reformulation of educational policy draws from human capital theory and emphasises accountability and the measurement of students’ achievement of technological skills against standard learning outcomes. The significance of the political dimension on the development of educational policies for ICT is discussed, with the conclusion that the exclusion of particular constituent groups can result in narrowly defined educational needs.
Projections of demand and capacity for colonoscopy related to increasing rates of colorectal cancer screening in the United States
Authors: Vijan S. , Inadomi J. , Hayward R. A. , Hofer T. P. , Fendrick A. M. 
Published: August 2004

SummaryBackground : There is debate about the optimal colorectal cancer screening test, partly because of concerns about colonoscopy demand.Aim : To quantify the demand for colonoscopy with different screening tests, and to estimate the ability of the United States health care system to meet demand.Methods : We used a previously published Markov model and the United States census data to estimate colonoscopy demand. We then used an endoscopic database to compare current rates of screening‐related colonoscopy with those projected by the model, and to estimate the number of endoscopists needed to meet colonoscopy demand.Results : Annual demand for colonoscopy ranges from 2.21 to 7.96 million. Based on current practice patterns, demand exceeds current supply regardless of screening strategy. We estimate that an increase of at least 1360 gastroenterologists would be necessary to meet demand for colonoscopic screening undergone once at age 65, while colonoscopy every 10 years could require 32 700 more gastroenterologists. A system using dedicated endoscopists could meet demand with fewer endoscopists.Conclusions : Colorectal cancer screening leads to demand for colonoscopy that outstrips supply. Systems to train dedicated screening endoscopists may be necessary in order to provide population‐wide screening. The costs and feasibility of establishing this infrastructure should be studied further.
Analyses of Cis ‐Acting and Trans ‐Acting Elements that are Crucial to Sustain Pregnancy‐Specific Glycoprotein Gene Expression in Different Cell Types
Authors: Koritschoner Nicolás P. , Panzetta‐Dutaiu Graciela M. , Bocco José L. , Dumur Catherine I. , Flury Alfredo , Patrito Luis C. 
Published: August 2004

Pregnancy‐specific β1 glycoprotein genes (PSG) are mainly expressed during human placental development, though their expression has been reported in other normal and pathological tissues, e.g. hydatidi‐form mole (HM), of distinct origins. However, the molecular components implicated in the regulation of PSG are not well understood. To identify some of the regulatory elements involved in the transcriptional control of PSG expression, the DNA‐protein interactions and the basal activities of the TATA‐box‐less PSG5 promoter were determined in different tissues and cell types. In DNAse‐I protection assays, DNA‐binding proteins from human term placenta (HTP) protected a region of 27 bp located from nucleotides –150 to –124, overlapping the farthest 5′ upstream cap site and resembling an initiator‐like element. In electrophoretic mobility shift assays (EMSA), three complexes were detected using nuclear extracts from HTP and an oligonucleotide containing the 27‐bp motif. In situ ultraviolet crosslinking analysis of the specific complexes revealed that two proteins of 78.0 kDa and 53.0 kDa are involved in such interactions, in accordance with the bands of 80.0 kDa and 57.5 kDa observed by Southwestern blotting. Competitive EMSA using mutant oligonucleotides with the substitution of 5′ACCCAT3′ by 5′GATATC3′ within the 27‐bp motif revealed that this sequence is fundamental for the formation of the specific DNA‐protein complexes. We show in transient transfection experiments performed in HeLa, COS‐7 and JEG‐3 cells, that such mutation completely abolished the transcriptional activity of the PSG5 promoter, independently of the cell type.Moreover, this mutation disrupted the formation of the specific DNA‐protein complexes which were essentially the same as those displayed by HTP. We also determined the binding activities of nucleopro‐teins derived from placental tissues in earlier developmental and pathological stages, i.e. first trimester placenta (1‐TRIM) and HM, respectively, showing that the DNA‐binding patterns were different from each other and distinct from those elicited by HTP. Our results indicate that the cis ‐acting and trans ‐acting elements analyzed are indispensable to support PSG5 promoter activity in cell lines which do or do not produce PSG. In addition, these elements appear to play a role in the mechanisms involved in PSG basal expression during placental development and differentiation.
Purification and Characterization of Human Topoisomerase I Mutants
Authors: Jensen Anne Dam , Svejstrup Jesper Q. 
Published: August 2004

A system for rapid purification and characterization of eukaryotic topoisomerase‐I mutants has been developed. The system utilizes six‐histidine tagging of human topoisomerase I expressed in Saccharomyces cerevisiae to enable purification by nickel‐affinity chromatography. Virtually homogenous mutant proteins are then tested for their ability to relax supercoiled DNA plasmids and their capacity for binding, cleaving and religating short defined DNA substrates.Relaxation‐deficient mutants were obtained by site‐directed mutagenesis of selected highly conserved amino acids. The mutants Tyr723Phe (active site mutation), Arg488Gln and Lys532Glu were inert in relaxation of DNA, whereas Lys720Glu showed a 50‐fold reduction in specific relaxation activity. Accordingly, only Lys720Glu showed low, but detectable cleavage activity on suicide DNA substrates, uncoupling the cleavage and religation events of topoisomerase I. The relative religation efficiency of Lys720Glu was comparable to that of wild‐type topoisomerase I, indicating that Lys720 is involved in interactions important for normal DNA cleavage, but not for the religation reaction. All mutants could be cross linked by ultraviolet light to bromo‐dUTP‐substituted DNA oligonucleotides carrying a topoi‐somerase‐I‐binding site, indicating that the deficiency of Tyr723Phe, Arg488Gln and Lys532Glu in DNA relaxation and cleavage is not due to an inability of these mutants to bind DNA non‐covalently.
Regulation of Expression of the Rat Serine Protease Inhibitor 2.3 Gene by Glucocorticoids and Interleukin‐6
Authors: Simar‐Blanchet Anne‐Emmanuelle , Paul Conception , Mercier Louis , Le Cam Alphonse 
Published: August 2004

The rat serine protease inhibitor 2.3 gene (spi 2.3) is almost completely silent in normal animals and is transiently expressed during acute inflammation. It encodes a potential anti‐elastase which is likely to play a major physiological role for the host defense. Two well‐known inflammatory mediators, glucocorticoids and interleukin‐6 (IL‐6) activate the spi 2.3 promoter and increase steady‐state levels of mRNA in cultured hepatocytes. GC activation is mediated by a single glucocorticoid‐response element which seems to act autonomously. A unique array of four functional IL‐6‐response sites was identified in the spi 2.3 promoter. Three of them (C‐II–IV) bear structural identity to the CCAAT/enhancer‐binding‐protein‐binding site consensus sequence, whereas the forth closely resembles the consensus κB nuclear factor recognition motif. The C‐IV element, which is the most active, contains the motif 5′‐CTGGGA and binds the IL‐6‐inducible acute‐phase response factor present in liver nuclear extracts from inflamed rats. Both basal and IL‐6‐dependent activities of each individual cytokine‐response element tested separately are strongly down regulated by a recently identified regulatory sequence [Le Cam, A. & Legraverend, C. (1995) Eur. J. Biochem. 231, 620–6271, located in the 3′ untranslated region of the spi 2.3 gene. However, this repressor element does not significantly affect overall IL‐6‐dependent spi 2.3 promoter activity. This suggests that, in the context of the active gene in vivo, all four IL‐6‐response sites, which are largely redundant, cooperate to overcome the strong repressive effect of the 3′ untranslated region silencer and are needed to bring about a maximal TL‐6 response.These data reveal a novel type of regulation of an acute‐phase gene involving different classes of IL‐6‐response elements controlled by a repressor and acting in conjunction with a glucocorticoid‐response element.
The Mitochondrial Permeability Transition Pore is Modulated by Oxidative Agents Through Both Pyridine Nucleotides and Glutathione at Two Separate Sites
Authors: Chernyak Boris V. , Bernardi Paolo 
Published: August 2004

We studied the modulation of the permeability transition pore (MTP), a cyclosporin‐A‐sensitive channel, in deenergized mitochondria. Rat liver mitochondria were incubated in a potassium gluconate medium and treated with uncoupler, valinomycin, oligomycin and A23187. Under these conditions the membrane and Donnan potentials are collapsed, and no ion gradients are maintained, allowing the study of the dependence of MTP opening on the Ca2+ concentration under a variety of oxidative conditions without the complexities arising from changes of the membrane potential and matrix pH, and from secondary‐ion redistribution.Cross‐linking of mitochondrial dithiols with arsenite or phenylarsine oxide, or treatment with tert ‐butylhydroperoxide leading to complete oxidation of glutathione, increased the sensitivity of MTP opening to Ca2+. This effect could be fully prevented by prior treatment of mitochondria with monobromobimane and restored by reduction with dithiothreitol. The effect of tert‐butylhydroperoxide was not additive with that of AsO, and it was completely blocked by modification of reduced glutathione with 1‐chloro 2,4‐dinitrobenzene through glutathione‐S‐transferase, indicating that oxidized glutathione affects the pore through the AsO‐reactive and PhAsO‐reactive dithiol.Oxidation of mitochondrial pyridine nucleotides by a variety of treatments also increased the sensitivity of MTP opening to Ca2+ under conditions where glutathione was maintained in the reduced state. This effect could be fully prevented when reduced pyridine nucleotides levels were reestablished with 2‐hydroxybutyrate but not by treatment with monobromobimane or dithiothreitol.The effects of dithiol cross‐linking or oxidation, and of pyridine nucleotide oxidation on the MTP were additive. The contribution of each of these two oxidative events, when they were induced at the same time, could still be selectively blocked by monobromobimane and dithiothreitol, or by 2‐hydroxybutyrate, respectively. Complete oxidation of pyridine nucleotides did not affect the reactivity of the dithiol towards monobromobimane, indicating that it remained in the reduced state.After transient opening of the MTP, sensitivity to pyridine nucleotide oxidation was lost while sensitivity to dithiol cross‐linking was retained. These data indicate that the dithiol belongs to an MTP regulatory component which is larger than the MTP cutoff of about 1500 Da, or is non‐diffusible. Taken together, these findings indicate that the MTP is influenced by oxidation‐reduction events at two separate sites that can be distinguished experimentally, and that these sites are not connected by common oxidation‐reduction intermediates other than glutathione.
Electropermeabilization of Intact Maize Cells Induces an Oxidative Stress
Authors: Sabri Naïma , Pelissier Bernard , Teissié Justin 
Published: August 2004

By applying electric field pulses through cell suspensions, cell membranes can be permeabilized transiently, giving free access to the cytosol. Electropulsation is now routinely used in cell biology when introducing various molecules such as proteins and nucleic acids into the cell. But the molecular and cellular bases of cell electropermeabilization are still unclear. In the present study, we observed that electropermeabilization of intact black Mexican sweet (BMS) maize cells induces a generation of oxygen species (oxidative jump). Using the chemiluminescent probe lucigenin, we have shown that the electro‐induced chemiluminescent response depends on the level of the stress factor as shown by its dependence on the electric parameters (electric field intensity, duration, and number of pulses).While the electroinduced cell permeabilization has a short life, the oxidative jump that is triggered by this electropermeabilization is a much longer‐lived response. The electroinduced loss in viability is linearly correlated to permeabilization. However, there is no correlation between the oxidative jump and the loss in viability. The modulation of oxygen species electroinduction by antioxidant products (dimethylsulfoxide, sodium L‐ascorbate, and glutathione) does not lead to an increase in cell viability. Such results are different to those observed with mammalian cells and indicate that even if the same phenomenon is observed when pulsing mammalian or intact plant cells, the associated metabolic response is not the same.
Competitive adsorption and desorption of glyphosate and phosphate on clay silicates and oxides
Authors: Gimsing A. L. , Borggaard O. K. 
Published: August 2004

AbstractCompetitive adsorption of glyphosate and phosphate on goethite and gibbsite and on illite, montmorillonite and two kaolinites differing in surface area was evaluated. The results show that glyphosate and phosphate are competing for the adsorption sites, but the degree of competition depends on the adsorbent. On goethite the competition is very much in favour of phosphate, on gibbsite the competition is closer, but still phosphate is favoured, while on illite, montmorillonite and kaolinite the competition is almost equal. The amounts of glyphosate and phosphate, which can be adsorbed also depends on the adsorbent: the oxides adsorb more than the clay silicates. The amount adsorbed on kaolinite was dependent on the specific surface area. Changes in the surface area did not affect the competition between glyphosate and phosphate for adsorption sites. The results indicate that differences among soils of different mineralogical composition regarding the adsorption of glyphosate and phosphate can be expected.
Mössbauer spectra of α- and γ-polymorphs of FeOOH and Fe2O3 : effects of poor crystallinity and of Al-for-Fe substitution
Authors: De Grave E. , Barrero C. A. , Da Costa G. M. , Vandenberghe R. E. , Van San E. 
Published: August 2004

AbstractThis paper presents various aspects, revealed by Mössbauer spectroscopy, of structural and magnetic properties of Al-substituted small-particle soil-related oxides. For goethite we focus on the relations between the hyperfine fields on the one hand, and crystallinity and Al content on the other. It is argued that these relations only provide a rough estimate of the Al content in natural samples. The ferrimagnetic-like behaviour reflected in the external-field Mössbauer spectra (4.2 K, 60 kOe) of certain Al goethites is presented. The spectra obtained for lepidocrocites are not spectacular, but confirmed that up to ∼10 at.% Al can be incorporated in the structure. Three differently-made series of hematites are considered. The Morin transition and spin structures in hematite are very sensitive to crystallinity and Al content, and probably to the presence of structural OH–. Integral low-energy electron Mössbauer spectroscopy on non-substituted samples indicates that the Morin-transition temperature in the surface layers (2 to 5 nm) is not significantly shifted from the bulk value. Measurements in extremely high magnetic fields (140 kOe) have shown that a spin-flip transition is induced in highly-substituted samples which exhibit no Morin transition in zero field. The use of external fields is crucial for the characterization and precise determination of the hyperfine parameters and site occupancies for maghemites, and for phase analyses of magnetic soils.
Iron in soil kaolins from Indonesia and Western Australia
Authors: Hart R. D. , St Pierre T. G. , Gilkes R. J . , McKinley A. J. , Siradz S. , Singh Balwant 
Published: August 2004

AbstractSoil kaolins from Indonesia and Western Australia and a range of reference kaolins were studied using Mössbauer spectroscopy, electron paramagnetic resonance (EPR) spectroscopy and SQUID magnetometry. Mössbauer spectra indicate that the Fe within the kaolins is in the highspin Fe3+oxidation state and that a large fraction of the Fe is present as dispersed atoms residing within the octahedral sites of the kaolinite crystal structure. The EPR spectra are typical for soil kaolins except for the absence of radiation-induced defects for the Indonesian kaolins. The Fe(I)spectra are dominant with a strong symmetric peak atg= 4.3, the presence of Fe(II) spectra is shown by a shoulder on this peak atg= 4.9 and a small phase up peak atg= 9.2.Low-temperature (5 K) magnetization (M) measurements over large field (H) sweeps (±70 kOe) yieldedM(H) curves which are fitted well with Brillouin functions indicating the paramagnetic nature of the kaolins at temperatures down to 5 K. A very small remanent magnetization was detectable in the kaolins. Remanent magnetization to saturation magnetization ratios ranged from 10–4to 10–3for the Indonesian kaolins and were all ∼10–3for the Western Australian kaolins, indicating that at high fields the vast majority of the magnetization of the kaolins is due to paramagnetic ions.Zero-field-cooled and field-cooled magnetization measurements in small fields (500 Oe) indicate that the Indonesian kaolins are generally free from magnetically-blocked material down to a temperature of 5 K. The magnetic susceptibility of the Indonesian kaolins shows Curie Law behaviour indicating paramagnetic behaviour over all temperatures down to 5 K. Measurements on the Western Australian kaolins indicated the presence of some magnetic material that is magnetically blocked at temperatures below ∼200 ­ 250 K. As a consequence, the magnetic susceptibility showed large deviations from Curie Law behaviour.
Prograde and retrograde diagenetic and metamorphic evolution in metapelitic rocks of Sierra Espuña (Spain)
Authors: Abad I . , Nieto F. , Peacor D. R. , Velilla N. 
Published: August 2004

AbstractAn unusually complete sequence of pelitic rocks ranging from diagenetic to greenschist-facies metamorphic grades occurs in southern Sierra Espun˜a, Spain. Prograde and retrograde reactions have been studied by X-ray diffraction and electron microscopy (SEM, TEM and AEM). The prograde reaction series, with reactions facilitated by tectonic stress, includes: (1) R4 interstratified illite-smectite in the diagenetic Malaguide Complex that preserves the variable orientation of original smectite packets, and has 1Md polytypism; (2) chemically heterogeneous illite and Na-K dioctahedral white micas that progressively evolve toward chemical and textural equilibrium in the anchizonal Intermediate Units; and (3) thick, defect-free packets of phengite, paragonite and clinochlore which have a typical metamorphic texture, in the Alpujarride Complex. Two superimposed retrograde episodes produced: (a) sudoite at near-peak metamorphic conditions and (b) dioctahedral smectite during low-temperature retrograde diagenesis.
Evolution of mineral assemblages and textures from sediment through hornfels in the Salton Sea Geothermal Field: Direct crystallization of phyllosilicates in a hydrothermal-metamorphic system
Authors: Giorgetti G. , Mata M. P. , Peacor D. R. 
Published: August 2004

AbstractMicroanalytical data on Plio-Pleistocene sediments from a Salton Sea Geothermal Field well define the evolution of textures and mineral assemblages from sediment to metamorphic rock in an open hydrothermal system.At shallow depths detrital grains occur within a fine-grained matrix of I-S and illite. As depth and temperature increase, grains lose their detrital characteristics; they subsequently form a continuous intergrown array of irregular domains, with phyllosilicates occupying the progressively decreasing pore space.Illite and chlorite are authigenic phyllosilicates down to 2500 m, where biotite occurs. Authigenic phyllosilicates occur as subhedral crystals (200 –600 Å thick). Alkali feldspar has end-member compositions, implying exchange of alkalis with convected fluids. Changes in texture imply dissolution of detrital phases and neocrystallization of authigenic phyllosilicates directly from pore fluids. Changes with depth are not time-dependent for phyllosilicates: they formed simultaneously at all depths as a result of a single hydrothermal event in an open system.