bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gabapentin fails to alter P/Q‐type Ca2+ channel‐mediated synaptic transmission in the hippocampus in vitro
Authors: Brown Jon T. , Randall Andrew 
Published: January 2005

AbstractGabapentin (Neurontin) has been successfully used in the treatment of both epilepsy and neuropathic pain. Despite its widespread clinical use, its mechanism of action is very poorly understood. Indeed, the only protein it is known to interact with is the α2δ subunit of the voltage‐gated Ca2+ channel complex. In a recent article, gabapentin was reported to inhibit synaptic transmission in the spinal cord through an inhibitory effect on presynaptic P/Q‐type Ca2+ channels in both glutamatergic primary afferents and glycinergic interneuones. To examine if such inhibition of P/Q‐channel‐mediated synaptic transmission by gabapentin generalised to other synaptic pathways, we tested the actions of gabapentin of P/Q‐type Ca2+ channel‐mediated synaptic responses in the CA1 subfield of the hippocampus. We found that gabapentin was completely inactive on such synaptic responses even at 10 times the maximally effective concentration used in the spinal cord. A small (∼10%) but consistent depression of control synaptic responses was elicited by 10 μM gabapentin. No greater response was observed at a 10 times higher concentration. From these data we conclude that gabapentin is not a generic inhibitor of presynaptic P/Q‐type channels and its actions at the spinal level must represent a feature of the P/Q‐type channel not present in the hippocampus. Given the known interactions of this compound, the best candidate for this is the presence, subtype, or state of the α2δ subunit. Synapse 55:262–269, 2005. © 2005 Wiley‐Liss, Inc.
Demonstration of hyperaccumulation of [18F]2‐fluoro‐2‐deoxy‐D‐glucose under oxygen deprivation in living brain slices using bioradiography
Authors: Sasaki Toru , Yamaguchi Mie , Kojima Shuji 
Published: January 2005

AbstractTo clarify the mechanism of hyperaccumulation of glucose in acute brain ischemia by PET, changes of glucose metabolism and mitochondrial electron transfer function were examined in living brain slices in vitro during control, hypoxic, and anoxic conditions by positron autoradiography using [18F]2‐fluoro‐2‐deoxy‐D‐glucose ([18F]FDG) and [15O]oxygen. [15O]Oxygen fixation reflecting mitochondrial electron transfer function was reduced and [18F]FDG uptake reflecting glucose metabolism was increased in proportion to the strength of oxygen deprivation during anoxia and hypoxia. Mitochondrial electron transfer function decreased with no regional differences, whereas the glucose metabolism was the most enhanced in the hippocampus and thalamus. The enhanced glucose metabolism was associated with an increased glutamate efflux after hypoxia and anoxia. Glucose metabolism was also increased by the addition of glutamate and was attenuated by the N‐methyl‐D‐aspartate (NMDA) receptor antagonist MK‐801 in the hippocampus and thalamus. The hyperaccumulation of glucose in acute brain ischemia was demonstrated in living brain slices using bioradiography with reduced mitochondrial electron transfer. The activation of NMDA receptors by glutamate during acute brain ischemia might be responsible for hyperutilization of glucose in the hippocampus and thalamus. Synapse 55:252–261, 2005. © 2005 Wiley‐Liss, Inc.
Multiple ionization in quantitative XRF
Authors: Ebel Horst , Svagera Robert , Ebel Maria F. 
Published: January 2005

AbstractThe influence of the neglect of multiple ionizations in quantitative XRF without standards is demonstrated by computer simulation and evaluation of characteristic x‐ray signals of binary bulk specimens of Al and Cu. An error of up to 4 wt% can be expected. Copyright © 2001 John Wiley & Sons, Ltd.
Elemental mapping using proton‐induced x‐rays
Authors: Przybyłowicz W. J. , Mesjasz‐Przybyłowicz J. , Pineda C. A. , Churms C. L. , Ryan C. G. , Prozesky V. M. , Frei R. , Slabbert J. P. , Padayachee J. , Reimold W. U. 
Published: January 2005

AbstractThe use of particle‐induced x‐ray emission (PIXE) in conjunction with a scanning nuclear microprobe (SNM) offers one of the few microanalytical techniques capable of studies of elemental concentrations at the ppm level, with a spatial resolution of the order of 1 µm. Beam scanning capabilities and advanced data treatment make it a technique of choice for quantitative two‐dimensional studies of elemental distribution. Although the ultimate aim is to obtain true quantitative elemental maps, free of concentration or thickness artifacts, some compromises are necessary owing to experimental and computational restrictions. Some approaches currently used are discussed with emphasis on true elemental imaging using the dynamic analysis method. Examples of applications in geology and biology are shown to illustrate its benefits and limitations. Copyright © 2001 John Wiley & Sons, Ltd.
Application of large‐area avalanche photodiodes to energy‐dispersive x‐ray fluorescence analysis
Authors: Fernandes L. M. P. , Lopes J. A. M. , dos Santos J. M. F. , Conde C. A. N. 
Published: January 2005

AbstractThe performance of several large‐area avalanche photodiodes (LAAPDs) for application to x‐ray spectrometry at room temperature was investigated. Optimum detector performance was obtained for gains of about 50–70. Good energy linearity of the LAAPDs' response to x‐rays was observed up to energies of about 25 keV. For this energy range the space charge effects are negligible for gains below 100–150. The energy resolutions obtained with LAAPDs can be better than those obtained with proportional counters. Our results indicate that the energy resolution of an LAAPD is better than that of a proportional counter only when the LAAPD maximum dark current is <300 nA. For this case, minimum detectable x‐ray energies of about 1 keV are possible. Spatial non‐uniformity is responsible for an absolute increase of 1–2% in energy resolution at 6 keV when illumination of the LAAPD is broadened from 1 mm diameter to full area. Counting rates up to 5 × 104 counts s−1 are possible without significant degradation of detector performance. Copyright © 2001 John Wiley & Sons, Ltd.
Upgrade of the x‐ray fluorescence beamline at HASYLAB/DESY
Authors: Falkenberg G. , Clauss O. , Swiderski A. , Tschentscher Th. 
Published: January 2005

AbstractA new x‐ray optical system for the fluorescence beamline L at HASYLAB is currently under construction and its commissioning phase will start early in 2001. Basis elements of the optical system are a double single‐crystal — double multilayer monochromator, x‐ray mirrors and capillary optics. The high‐resolution Si crystal monochromator is designed for microscopic x‐ray absorption near‐edge structures (µ‐XANES) experiments in fluorescence mode for laterally resolved speciation of trace elements. Broadband excitation by the multilayer monochromator will be used in total reflection x‐ray fluorescence (TXRF) experiments and microscopic x‐ray fluorescence analysis (µ‐XRF). An energy range of 2.4–80 keV will be explored by the monochromator system, giving access to the K‐edges of elements with 16 < Z < 79. A set of plane and cylindrical x‐ray mirrors allows a high‐energy cut‐off at 12 and 30 keV, respectively and optional prefocusing. The microfocus is generated by monocapillaries and polycapillaries. The performance of different monocapillary optics in the synchrotron beam was measured in polychromatic and monochromatic modes. Copyright © 2001 John Wiley & Sons, Ltd.
PIXE analysis of human brain tissue
Authors: Boruchowska M. , Lankosz M. , Adamek D. , Korman A. 
Published: January 2005

AbstractThe proton induced x‐ray emission (PIXE) technique was used for localized analysis of trace elements in small quantities of medical samples. Both white and gray matter of the human brain were studied. The tissue samples were taken at autopsy from patients aged from 17 to 88 years. Qualitative and quantitative analyses were performed. NIST SRM 1577b Bovine Liver and SRM 1566a Oyster Tissue were used as external standards for the determination of trace element mass fractions in the brain specimens. The main goal of these preliminary studies was to evaluate approaches for the quantitative analysis of medical materials using PIXE taking into account the effect of patient age on the accumulation of elements and the regional distribution of elements in human brain. Detection and quantification limits were calculated for selected elements. Elevation of Zn concentration with age of patients was observed for white mater of the human brain. Elements such as S, K, Ca, Mn, Fe, Cu and Zn clearly exhibit higher mass fractions in grey matter than in white matter in all cases. This investigation confirms that PIXE is a useful technique for multielement analysis of tissue samples with good sensitivity. Copyright © 2001 John Wiley & Sons, Ltd.
X‐ray waveguide phenomenon in thin layers under grazing incidence conditions.
Authors: Ebel Horst , Svagera Robert , Ebel Maria F. 
Published: January 2005

AbstractHayashi et al. published a paper on refracted x‐rays propagating near the surface under grazing incidence conditions. For pure silicon wafers the refraction can be described by Snell's law, whereas for thin n‐C33H86 layers on silicon wafers an additional beam occurs. An interesting feature of this beam is the constant photon energy over a wide range of take‐off angles. The authors suggested that the layer acts as a waveguide and a suitable x‐ray refraction theory for thin films is required. The present investigation deals with the interpretation of the waveguide phenomenon by the concept of an interference between two plane wave fields propagating under angles ±ϕ. The experimental results of Hayashi et al. are in good agreement with our calculated values. Copyright © 2001 John Wiley & Sons, Ltd.
Chronological lifespan of stationary phase yeast cells; a model for investigating the factors that might influence the ageing of postmitotic tissues in higher organisms
Authors: MacLean Morag , Harris Nicholas , Piper Peter W. 
Published: January 2005

AbstractBudding yeast can be considered to have two distinct lifespans: (a) a replicative (budding, non‐chronological) lifespan, measured as the number of daughters produced by each actively dividing mother cell; and (ii) a chronological lifespan, measured as the ability of stationary cultures to maintain viability over time. In non‐dividing cells, essential components that become damaged cannot be diluted out through cell division but must, of necessity, be turned over and renewed. By elevating stress resistances, many of the activities needed for such renewal should be elevated with commensurate reduction in the steady‐state levels of damaged cell components. Therefore, chronological lifespan in particular might be expected to relate to stress resistance. For yeast to attain a full chronological lifespan requires the expression of the general stress response. It is more important, though, that the cells should be efficiently adapted to respiratory maintenance, since it is cultures grown to stationary phase on respiratory media that usually display the longest chronological lifespans. For this reason, respiration‐adapted cells potentially provide a better model of chronological ageing than cultures pre‐grown on glucose. Copyright © 2001 John Wiley & Sons, Ltd.
The activity of plasma membrane H+‐ATPase is strongly stimulated during Saccharomyces cerevisiae adaptation to growth under high copper stress, accompanying intracellular acidification
Authors: Fernandes Alexandra R. , Sá‐Correia Isabel 
Published: January 2005

AbstractFor the adaptation of cells of Saccharomyces cerevisiae, a period of latency is necessary before exponential growth is resumed in a medium supplemented with a highly inhibitory concentration of copper. In this work, we have examined some physiological responses occurring during this period of adaptation. The results revealed that plasma membrane H+‐ATPase (PM‐ATPase) activity is strongly stimulated (up to 24‐fold) during copper‐induced latency in growth medium with glucose, reaching maximal levels when the cells were about to start inhibited exponential growth. This in vivo activation of the ATPase activity by copper was accompanied by the stimulation of the H+‐pumping activity of the enzyme in vivo and was essentially due to the increase of the apparent Vmax for MgATP. Although the exact molecular basis of the reported plasma membrane ATPase activation was not clarified, no increase in the mRNA levels from the encoding genes PMA1 and PMA2 was apparently detected during copper‐induced latency. The physiological response reported here may allow the cells to cope with copper‐induced lipid peroxidation and consequent decrease in plasma membrane lipid ordering and increase in the non‐specific permeability to protons. The consequences of these copper deleterious effects were revealed by the decrease of the intracellular pH (pHi) of the yeast population, from approximately pHi 6 to pHi 5, during copper‐induced latency in growth medium at pH 4.3. The time‐dependent patterns of plasma membrane ATPase activation and of the decrease of pHi during the period of adaptation to growth with copper correlate, suggesting that the regulation of this membrane enzyme activity may be triggered by intracellular acidification. Consistent with this idea, when exponential growth under copper stress was resumed and the pHi of the yeast population recovered up to physiological values, plasma membrane ATPase activity simultaneously decreased from the highly stimulated level attained during the adaptation period of latency. Copyright © 2001 John Wiley & Sons, Ltd.
A new family of yeast vectors and S288C‐derived strains for the systematic analysis of gene function
Authors: Tomlin Gregory C. , Wixon Joanne L. , Bolotin‐Fukuhara Monique , Oliver Stephen G. 
Published: January 2005

AbstractThe yeast genome has been shown to contain a significant number of gene families with more than three members. In order to study these families it is often necessary to generate strains carrying deletions of all members of the family, which can require a wide range of auxotrophic markers. To facilitate such studies, we have generated yeast strains containing deletions of a selection of nutritional marker genes (ade2, ade4, ade8, met3 and met14). We have also cloned the corresponding cognate genes, allowing their use in PCR‐based gene disruptions. Two new pRS family Saccharomyces cerevisiae–Escherichia coli shuttle vectors containing ADE8 (one low‐copy, pRS4110, and one high‐copy, pRS4210) have been produced for use in conjunction with the new strains. A system for easier synthetic lethal screening using one of these new markers is also presented. The ADE8 and HIS3 genes have been cloned together on a high‐copy vector (pRS4213), providing a plasmid for red–white colour screening in the ade2Δ0 ade8Δ0 strains we have generated. In contrast to some conventional systems, this plasmid allows for screening using gene libraries constructed in URA3 plasmids. Copyright © 2001 John Wiley & Sons, Ltd.
Assessment of prediction accuracy of protein function from protein–protein interaction data
Authors: Hishigaki Haretsugu , Nakai Kenta , Ono Toshihide , Tanigami Akira , Takagi Toshihisa 
Published: January 2005

AbstractFunctional prediction of open reading frames coded in the genome is one of the most important tasks in yeast genomics. Among a number of large‐scale experiments for assigning certain functional classes to proteins, experiments determining protein–protein interaction are especially important because interacting proteins usually have the same function. Thus, it seems possible to predict the function of a protein when the function of its interacting partner is known. However, in vitro experiments often suffer from artifacts and a protein can often have multiple binding partners with different functions. We developed an objective prediction method that can systematically include the information of indirect interaction. Our method can predict the subcellular localization, the cellular role and the biochemical function of yeast proteins with accuracies of 72.7%, 63.6% and 52.7%, respectively. The prediction accuracy rises for proteins with more than three binding partners and thus we present the open prediction results for 16 such proteins. Copyright © 2001 John Wiley & Sons, Ltd.
Hut1 proteins identified in Saccharomyces cerevisiae and Schizosaccharomyces pombe are functional homologues involved in the protein‐folding process at the endoplasmic reticulum
Authors: Nakanishi Hideki , Nakayama Ken‐ichi , Yokota Ayako , Tachikawa Hiroyuki , Takahashi Nobuhiro , Jigami Yoshifumi 
Published: January 2005

AbstractThe Saccharomyces cerevisiae HUT1 gene (scHUT1) and the Schizosaccharomyces pombe hut1+ gene (sphut1+) encode hydrophobic proteins with approximately 30% identity to a human UDP–galactose transporter‐related gene (UGTrel1) product. These proteins show a significant similarity to the nucleotide sugar transporter and are conserved in many eukaryotic species, but their physiological functions are not known. Both scHUT1 and sphut1+ genes are non‐essential for cell growth under normal conditions, and their disruptants show no defects in the modification of O‐ and N‐linked oligosaccharides, but are sensitive to a membrane‐permeable reducing agent, dithiothreitol (DTT). Consistent with this phenotype, scHUT1 has genetic interaction with ERO1, which plays an essential role in the oxidation of secretory proteins at the endoplasmic reticulum (ER). Overexpression of the MPD1 or MPD2 genes, which were isolated as multicopy suppressors of protein disulphide isomerase (PDI) depletion, could not replace the essential function of PDI in Δhut1 S. cerevisiae cells. Our results indicate that scHut1p and spHut1p are functional homologues, and their physiological function is to maintain the optimal environment for the folding of secretory pathway proteins in the ER. Copyright © 2001 John Wiley & Sons, Ltd.
Multicopy suppressors of the sly1 temperature‐sensitive mutation in the ER–Golgi vesicular transport in Saccharomyces cerevisiae
Authors: Kosodo Yoichi , Imai Keita , Hirata Aiko , Noda Yoichi , Takatsuki Akira , Adachi Hiroyuki , Yoda Koji 
Published: January 2005

AbstractSaccharomyces cerevisiae Sly1 protein is a member of the Sec1/Munc18‐family proteins, which are essential for vesicular trafficking, but their exact biological roles are yet to be determined. A temperature‐sensitive sly1 mutant arrests the vesicular transport from the ER to Golgi compartments at 37°C. We screened for multicopy suppressor genes that restore the colony formation of the sly1ts mutant to discover functionally interacting components. The suppressor genes obtained were classified as: (1) those that encode a multifunctional suppressor, SSD1; (2) heat shock proteins, SSB1 and SSB2; (3) cell surface proteins, WSC1, WSC2 and MID2; (4) ER–Golgi transport proteins, USO1 and BET1; and (5) an as‐yet‐uncharacterized protein, HSD1 (high‐copy suppressor of SLY1 defect 1). By epitope tagging of the gene product, we found that Hsd1 protein is an ER‐resident membrane protein. Its overproduction induced enlargement of ER‐like membrane structures. Copyright © 2001 John Wiley & Sons, Ltd.
Identification and characterization of Saccharomyces cerevisiae strains isolated from West African sorghum beer
Authors: van der Aa Kühle Alis , Jesperen Lene , Glover Richard L.K. , Diawara Bréhima , Jakobsen Mogens 
Published: January 2005

AbstractThe occurrence and characterization of yeasts isolated from sorghum beer produced in Ghana and Burkina Faso, West Africa, were investigated. The yeasts involved in the fermentations were found to consist of Saccharomyces spp. almost exclusively. Of the isolates investigated, 45% were identified as Saccharomyces cerevisiae, whereas more than half of the isolates (53%) had physiological properties atypical of S. cerevisiae or any other member of the complex sensu strictu, as they were able to assimilate only glucose, maltose and ethanol as carbon sources. Both ITS–PCR RFLP and PFGE strongly indicated that these isolates were related to S. cerevisiae, regardless of their phenotypic characteristics. Sequencing of the D1/D2 domain of the 26S rDNA confirmed the close relatedness to S. cerevisiae with 0.5% nucleotide differences. The MAL1 and MAL3 loci were found for all isolates as the only recognized MAL loci. Besides, for 40% of the isolates the MAL61 probe hybridized to a position of about 950 kbp, which has not formerly been described as a MAL locus. The results showed that the spontaneous fermentation of West African sorghum beer is dominated by a variety of strains of S.cerevisiae not previously described, among which starter cultures should be selected. Copyright © 2001 John Wiley & Sons, Ltd.
Expression and activity of the Hxt7 high‐affinity hexose transporter of Saccharomyces cerevisiae
Authors: Ye Ling , Berden Jan A. , van Dam Karel , Kruckeberg Arthur L. 
Published: January 2005

AbstractHigh‐affinity hexose transport is required for efficient utilization of low hexose concentrations by the baker's yeast Saccharomyces cerevisiae. These low concentrations occur during the late exponential phase of batch growth on hexoses, during hexose‐limited chemostat or fed‐batch culture, or during growth on sugars such as sucrose and raffinose that are hydrolysed to hexoses outside the cell. The expression of the Hxt7 high‐affinity glucose transporter of S. cerevisiae was examined during batch growth on glucose medium in a wild‐type strain and a strain expressing only HXT7 (i.e. with null mutations in HXT1–HXT6). In the wild‐type strain, HXT7 transcription was repressed at high glucose and was detected when the glucose in the culture approached depletion. In the HXT7‐only strain, transcription of HXT7 was constitutive throughout the glucose growth phase and was increased further at low glucose concentrations. After glucose depletion, the levels of HXT7 mRNA declined rapidly in both strains. In contrast, the Hxt7 protein was relatively stable after glucose depletion. By monitoring the subcellular localization of an Hxt7::GFP fusion protein it was observed that Hxt7 was localized in the plasma membrane, even when expressed at high glucose concentrations in the HXT7‐only strain. After glucose depletion Hxt7 was gradually endocytosed and targeted to the vacuole for degradation. The Hxt7::GFP fusion protein was a fully functional hexose transporter with a catalytic centre activity of approximately 200/sec. It is concluded that repression of HXT7 and degradation of Hxt7 at high glucose concentrations is dependent on a high glucose transport capacity. Copyright © 2001 John Wiley & Sons, Ltd.