bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cerebral pyruvate carboxylase flux is unaltered during bicuculline‐seizures
Authors: Patel Anant B. , Chowdhury Golam M.I. , de Graaf Robin A. , Rothman Douglas L. , Shulman Robert G. , Behar Kevin L. 
Published: November 2004

AbstractGlutamine synthesis in the astroglia reflects the sum of neurotransmitter cycling (glutamate and γ‐aminobutyric acid [GABA]) and de novo synthesis (anaplerosis), the latter catalyzed by pyruvate carboxylase. Previous studies have shown that the glutamate plus GABA cycling flux is correlated strongly with neuronal activity; however, the relationship between pyruvate carboxylase flux and neuronal activity is not known. In this study, pyruvate carboxylase flux was assessed during intravenous infusion of [2‐13C]glucose using localized 1H‐[13C] NMR spectroscopy at 7 Tesla in vivo in halothane‐ anesthetized and ventilated adult Wistar rats during 85 min of bicuculline‐induced seizures (1 mg/kg, intravenously) and in nontreated controls. During seizures, concentrations of lactate, alanine, glutamine, GABA, and succinate increased whereas glutamate and aspartate decreased such that the decrease in glutamate plus aspartate equaled the increase in glutamine plus GABA. Pyruvate carboxylase flux was assessed by the sum of [2‐13C] and [3‐13C] of glutamine and glutamate (Glx2+3) labeling during [2‐13C]glucose infusion. During seizures the initial rate of Glx2+3 synthesis (0.069 ± 0.013 μmol/g/min) was not significantly different (P = 0.68) from that of the controls (0.059 ± 0.010 μmol/g/min), indicating that anaplerotic flow through pyruvate carboxylase was unaltered. Intense neuronal activation of seizures did not seem to increase anaplerosis through pyruvate carboxylase, despite the substantial increase in neuronal activity and glutamate/glutamine cycling shown in a previous study (Patel et al., 2004b). © 2004 Wiley‐Liss, Inc.
Interscan registration using navigator echoes
Authors: Welch Edward Brian , Manduca Armando , Grimm Roger C. , Jack Clifford R. 
Published: November 2004

AbstractA common problem in clinical MRI is anatomic misalignment of imaging slices across successive examinations. This unnecessarily complicates the radiologic assessment of anatomic change over time on serial MRI studies. To address this problem, spherical navigator echoes, which can detect rigid body motion in all six degrees of freedom, were used to guide spatial location and orientation adjustments to an exam prescription to match the reference frame of images acquired in an earlier exam. An initial linear navigator echo is also necessary to effect coarse Z translation adjustments prior to fine six degrees of freedom adjustment with a spherical navigator echo. Results of this technique are presented for head image volumes of five volunteers. Each volunteer was imaged on two scanners. In all cases, the reference frame adjustments provided by the navigator echoes substantially improved the alignment of the latter exam and performed well compared to retrospective image‐based registration. Magn Reson Med 52:1448–1452, 2004. © 2004 Wiley‐Liss, Inc.
MRI of transplanted pancreatic islets
Authors: Jirák Daniel , Kríz Jan , Herynek Vít , Andersson Benita , Girman Peter , Burian Martin , Saudek František , Hájek Milan 
Published: November 2004

AbstractA promising treatment method for type 1 diabetes mellitus is transplantation of pancreatic islets containing β‐cells. The aim of this study was to develop an MR technique to monitor the distribution and fate of transplanted pancreatic islets in an animal model. Twenty‐five hundred purified and magnetically labeled islets were transplanted through the portal vein into the liver of experimental rats. The animals were scanned using a MR 4.7‐T scanner. The labeled pancreatic islets were clearly visualized in the liver in both diabetic and healthy rats as hypointense areas on T2*‐weighted MR images during the entire measurement period. Transmission electron microscopy confirmed the presence of iron‐oxide nanoparticles inside the cells of the pancreatic islets. A significant decrease in blood glucose levels in diabetic rats was observed; normal glycemia was reached 1 week after transplantation. This study, therefore, represents a promising step toward possible clinical application in human medicine. Magn Reson Med 52:1228–1233, 2004. © 2004 Wiley‐Liss, Inc.
Gradient field switching as a source for artifacts in MR imaging of metallic stents
Authors: Shenhav Avshalom , Azhari Haim 
Published: November 2004

AbstractMetallic implants, such as stents, have long been a concern in magnetic resonance imaging (MRI). In addition to safety issues, they are commonly associated with image artifacts. The mechanisms of radiofrequency‐ (RF) and susceptibility‐induced artifacts have been thoroughly investigated. However, gradient‐switching‐induced artifacts have not been analyzed. In this study it was demonstrated that gradient switching may be a source of artifacts in metallic stent MR imaging. These artifacts differ from those caused by the RF pulse. A theoretical explanation is provided as well. Magn Reson Med 52:1465–1468, 2004. © 2004 Wiley‐Liss, Inc.
Triple contrast technique for black blood imaging with double inversion preparation
Authors: Kim Seong‐Eun , Kholmovski Eugene G. , Jeong Eun‐Kee , Buswell Henry R. , Tsuruda Jay S. , Parker Dennis L. 
Published: November 2004

AbstractThis work reports on the development of a pulse sequence to simultaneously acquire proton density, T1, and T2 weighted images in a single magnetization prepared fast spin echo acquisition. The technique is based upon the application of a magnetization preparation consisting of a global inversion followed by slice‐selective 180° and 90° pulses to prepare the signal of specific slices. Slices are acquired in an interleaved manner with time delays appropriate for the desired image contrasts. Data acquisition is repeated for all combinations of slice interleaving covering the region of interest until images from all slice locations have been acquired with all desired image contrasts. The multiple image contrasts obtained with this technique should be useful in applications where discrimination between different types of tissue components is desired, such as in the analysis of plaque in cervical carotid artery disease. Magn Reson Med 52:1379–1387, 2004. © 2004 Wiley‐Liss, Inc.
Hyperpolarized 3He MRI of mouse lung
Authors: Dugas Joseph P. , Garbow Joel R. , Kobayashi Dale K. , Conradi Mark S. 
Published: November 2004

AbstractHyperpolarized 3He images of mouse lung are presented. Ventilation images and measurements of 3He apparent diffusion coefficient (ADC) are reported in healthy mice, and preliminary studies of emphysema and lung cancer in mice are described using these techniques. The design and operation of an electronically controlled small‐animal ventilator to deliver the hyperpolarized gas and control animal respiration are described. Images are acquired using an asymmetric gradient echo imaging method to enhance the signal‐to‐noise ratio of the rapidly diffusing 3He. In mice with elastase‐induced emphysema, the whole‐lung average ADC is greater by approximately 25%, a statistically significant difference, compared to healthy animals. By contrast, mice exposed to cigarette smoke for up to 12 months reveal no statistically relevant increases in ADC, although emphysema was not confirmed in these mice. A study of lung cancer (melanoma) in mice is also presented. While tumors are shown to cause substantial ventilation defects in the lung, these defects appear confined to the cancerous regions and do not extend to large‐scale regions of the lung distal to the tumors. Magn Reson Med 52:1310–1317, 2004. © 2004 Wiley‐Liss, Inc.
Robotically guided radiosurgery for children
Authors: Giller Cole A. , Berger Brian D. , Pistenmaa David A. , Sklar Frederick , Weprin Bradley , Shapiro Kenneth , Winick Naomi , Mulne Arlynn F. , Delp Janice L. , Gilio Joseph P. , Gall Kenneth P. , Dicke Karel A. , Swift Dale , Sacco David , Harris‐Henderson Kesha , Bowers Daniel 
Published: November 2004

AbstractBackgroundA robotically guided linear accelerator has recently been developed which provides frameless radiosurgery with high precision. Potential advantages for the pediatric population include the avoidance of the cognitive decline associated with whole brain radiotherapy, the ability to treat young children with thin skulls unsuitable for frame‐based methods, and the possible avoidance of general anesthesia. We report our experience with this system (the “Cyberknife”) in the treatment of 21 children.ProceduresCyberknife radiosurgery was performed on 38 occasions for 21 patients, age ranging from 8 months to 16 years (7.0 ± 5.1 years), with tumors considered unresectable. Three had pilocytic astrocytomas, two had anaplastic astrocytomas, three had ependymomas (two anaplastic), four had medulloblastomas, three had atypical teratoid/rhabdoid tumors, three had craniopharyngiomas, and three had other pathologies. The mean target volume was 10.7 ± 20 cm3, mean marginal dose was 18.8 ± 8.1 Gy, and mean follow‐up is 18 ± 11 months. Twenty‐seven (71%) of the treatments were single‐shot and eight (38%) patients did not require general anesthesia.ResultsLocal control was achieved in the patients with pilocytic and anaplastic astrocytoma, three of the patients with medulloblastoma, and the three with craniopharyngioma, but not for those with ependymoma. Two of the patients with rhabdoid tumors are alive 16 and 35 months after this diagnosis. There have been no procedure related deaths or complications.ConclusionCyberknife radiosurgery can be used to achieve local control for some children with CNS tumors without the need for rigid head fixation. © 2004 Wiley‐Liss, Inc.
Ab initio analysis of electron currents in thioalkanes
Authors: Seminario Jorge M. , Yan Liuming 
Published: November 2004

AbstractA combined density functional theory and Green's function procedure is used to calculate the electrical characteristics of a group of alkanethiols representing possible experimental settings. It is found that the current running through the molecule is the sum of the contributions from all molecular orbitals each presenting a barrier to electron transport equal to their energy difference from the Fermi level of the contacts. For the alkanethiols the location of these intrinsic barriers are at 0.78 eV (highest occupied molecular orbital [HOMO] and HOMO‐1), 1.99 eV (HOMO‐2 and HOMO‐3), 2.07 eV (LUMO and LUMO+1), and 2.67 eV (HOMO‐4). However, barriers obtained through fittings to known models do not bear any physical meaning at the molecular level, as they are sort of exponential average of the intrinsic barriers. We have also found that the exponential dependence of the current with the length of the alkane is practically independent of the contact nature, perhaps due to the large resistance of the alkanes. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Comparing the concentration curves directly in a pharmacokinetics, bioavailability/bioequivalence study
Authors: Liao Jason J. Z. 
Published: November 2004

AbstractIn a traditional pharmacokinetics (PK), bioavailability (BA) /bioequivalence (BE) study, the same number of time points and sampling times are used for each subject. Often, an indirect inference is then made on some PK parameters such as area under the plasma concentration curve (AUC), maximum plasma concentration (Cmax), time to maximum plasma concentration (Tmax) or half‐life. However, since these PK parameters are summarized from repeated measurements, a lot of information can be lost. The indirect inferences on some PK parameters are not always accurate. Taking the repeated measurements of the concentration curve into consideration, a functional linear model has been developed to compare concentration curves directly instead of the PK parameters. Considering the nature of repeated measurements, a multiple testing procedure is proposed to assess the equality of two concentration curves. A real data set is used to demonstrate the proposed procedure. Copyright © 2004 John Wiley & Sons, Ltd.
Supplementary winter feeding of wild red deer Cervus elaphus in Europe and North America: justifications, feeding practice and effectiveness
Authors: PUTMAN R. J. , STAINES B. W. 
Published: November 2004

ABSTRACT 1. Supplementary winter feeding of game animals, and particularly deer, is a common practice throughout northern (continental) Europe and parts of North America. Feeding is normally associated with maintaining high densities of animals for hunting, in terms of: (i) maintaining or increasing body weights and condition overwinter; (ii) improving reproductive performance and fertility; (iii) increasing overwinter survival; and (iv) reducing levels of damage caused to agriculture and forestry or the natural heritage. We consider the balance of evidence on the effectiveness of winter feeding of red deer Cervus elaphus in achieving these objectives. Where that evidence is equivocal, we attempt to reconcile apparent contradictions to evaluate the circumstances under which winter feeding may or may not be effective. 2. In general, feeding of red deer on open range appears to have relatively little effect on body weights or fecundity. Effects on increasing antler size and quality are variable and seem to depend on the degree to which animals may be mineral limited on native range. Effects on survival are similarly ambiguous. It is apparent, however, that to be effective in reducing mortality, any supplementation is required early in the season and not simply when heavy mortalities are already being experienced. If provision of supplementary foods is delayed until animals are perceived already to be in poor condition, such feeding may have little effect. 3. One of the primary goals of winter feeding in both Europe and the USA has become the prevention of environmental damage, particularly damage to commercial and native forests, while maintaining deer populations at densities suitable for hunting. Again, empirical evidence for effectiveness in this regard is inconclusive, with some studies showing a decrease in damage caused, some showing no effect and others showing a significant increase in local impact. 4. There are equally a number of problems associated with the provision of supplementary feeds overwinter. Those animals which come to the feeding stations may develop a reliance on the food supplement provided, reducing intake of natural forages to near zero; where feed provided is less than 100% of daily requirement, such animals may regularly lose, rather than gain condition. Feed provision is also extremely uneven at such feeding stations; dominant stags displace younger stags and hinds from the feed provided until they have themselves finished feeding. Concentrations of high densities of animals around small feed‐areas may also increase the risk of infection and lead to development of high parasite burdens. 5. In an attempt to assess the current status and distribution of supplementary winter feeding in Scotland, a questionnaire was circulated to a number of individual across the country. Results of this survey are summarized and conclusions presented on the likely effectiveness of current feeding practices in achieving their aims.
Does the presence of a human tracker affect the behaviour of radio‐tagged wood miceApodemus sylvaticus?
Authors: PROSSER PHIL , BROWN SARA , BROOKES KATE 
Published: November 2004

ABSTRACT1. While the effect on animals of handling them and fitting them with radio tags has been investigated, little work has been reported testing the effect of the presence of a human observer tracking an animal.2. The activity of wood mice fitted with radio collars and confined to a semifield pen was measured in the presence and the absence of a human observer. Free‐ranging wood mice were radio tracked by using two protocols: ‘fixes’ taken periodically, and periods of continuous tracking.3. There was no significant difference in any quantified aspect of the animals’ behaviour. This suggests that the presence of a human tracker has a negligible effect on the behaviour of wood mice.
Moral Hazard and Optimal Subsidiary Structure for Financial Institutions
Authors: KAHN CHARLES , WINTON ANDREW 
Published: November 2004

ABSTRACTBanks and related financial institutions often have two separate subsidiaries that make loans of similar type but differing risk, for example, a bank and a finance company, or a “good bank/bad bank” structure. Such “bipartite” structures may prevent risk shifting, in which banks misuse their flexibility in choosing and monitoring loans to exploit their debt holders. By “insulating” safer loans from riskier loans, a bipartite structure reduces risk‐shifting incentives in the safer subsidiary. Bipartite structures are more likely to dominate unitary structures as the downside from riskier loans is higher or as expected profits from the efficient loan mix are lower.
How to Discount Cashflows with Time‐Varying Expected Returns
Authors: ANG ANDREW , LIU JUN 
Published: November 2004

ABSTRACTWhile many studies document that the market risk premium is predictable and that betas are not constant, the dividend discount model ignores time‐varying risk premiums and betas. We develop a model to consistently value cashflows with changing risk‐free rates, predictable risk premiums, and conditional betas in the context of a conditional CAPM. Practical valuation is accomplished with an analytic term structure of discount rates, with different discount rates applied to expected cashflows at different horizons. Using constant discount rates can produce large misvaluations, which, in portfolio data, are mostly driven at short horizons by market risk premiums and at long horizons by time variation in risk‐free rates and factor loadings.
The Choice of Private Versus Public Capital Markets: Evidence from Privatizations
Authors: MEGGINSON WILLIAM L. , NASH ROBERT C. , NETTER JEFFRY M. , POULSEN ANNETTE B. 
Published: November 2004

ABSTRACTWe examine the impact of political, institutional, and economic factors on the choice between selling a state‐owned enterprise in the public capital market through a share issue privatization (SIP) and selling it in the private capital market in an asset sale. SIPs are more likely in less developed capital markets, for more profitable state‐owned enterprises, and where there are more protections of minority shareholders. Asset sales are more likely when there is less state control of the economy and when the firm is smaller. Our results suggest the importance of privatization activities in developing the equity markets of privatizing countries.
Enteropathogenic
Escherichia coli
Infection Triggers Host Phospholipid Metabolism Perturbations
Authors: Wu Y. , Lau B. , Smith S. , Troyan K. , Barnett Foster D. E. 
Published: November 2004

ABSTRACT

Enteropathogenic
Escherichia coli
(EPEC) specifically recognizes phosphatidylethanolamine (PE) on the outer leaflet of host epithelial cells. EPEC also induces apoptosis in epithelial cells, which results in increased levels of outer leaflet PE and increased bacterial binding. Consequently, it is of interest to investigate whether EPEC infection perturbs host cell phospholipid metabolism and whether the changes play a role in the apoptotic signaling. Our findings indicate that EPEC infection results in a significant increase in the epithelial cell PE level and a corresponding decrease in the phosphatidylcholine (PC) level. PE synthesis via both the de novo pathway and the serine decarboxylation pathway was enhanced, and de novo synthesis of phosphatidylcholine via CDP-choline was reduced. The changes were transitory, and the maximum change was noted after 4 to 5 h of infection. Addition of exogenous PC or CDP-choline to epithelial cells prior to infection abrogated EPEC-induced apoptosis, suggesting that EPEC infection inhibits the CTP-phosphocholine cytidylyltransferase step in PC synthesis, which is reportedly inhibited during nonmicrobially induced apoptosis. On the other hand, incorporation of exogenous PE by the host cells enhanced EPEC-induced apoptosis and necrosis without increasing bacterial adhesion. This is the first report that pathogen-induced apoptosis is associated with significant changes in PE and PC metabolism, and the results suggest that EPEC adhesion to a host membrane phospholipid plays a role in disruption of host phospholipid metabolism.
Downregulation of CXCR1 and CXCR2 Expression on Human Neutrophils byHelicobacter pylori: a New Pathomechanism inH. pyloriInfection?
Authors: Schmausser Bernd , Josenhans Christine , Endrich Simon , Suerbaum Sebastian , Sitaru Cassian , Andrulis Mindaugas , Brändlein Stephanie , Rieckmann Peter , Müller-Hermelink Hans Konrad , Eck Matthias 
Published: November 2004

ABSTRACTInHelicobacter pylorigastritis, neutrophil activation and migration, which play central roles in the pathogenesis of the disease, are regulated by the neutrophil attractant chemokines interleukin 8 (IL-8) and Groα, whose secretion is induced byH. pylori. However, the modulation of the corresponding chemokine receptors CXCR1 and CXCR2 on human neutrophils under the influence ofH. pylorihas not been investigated. Incubation of neutrophils withcag+andcagdeletionH. pyloristrains resulted in a complete downregulation of the CXCR1 and the CXCR2 receptors after 0.5 h, as tested by fluorescence-activated cell sorter analysis, independent of thecagstatus. Downregulation of CXCR1 and CXCR2 seems to occur via receptor internalization and rapid degradation, as shown by confocal microscopy and immunoblotting. Neither the proinflammatory cytokines IL-8 and tumor necrosis factor alpha produced by the neutrophils themselves norH. pylorilipopolysaccharide, which are the known regulators of these two chemokine receptors, was responsible for the downregulation. Reverse transcription-PCR analysis showed that CXCR1 and CXCR2 mRNAs of neutrophils were reduced at a later time than the CXCR1 and CXCR2 proteins. Moreover,cag+H. pyloristrains induced significantly stronger downregulation of CXCR1 and CXCR2 mRNAs than thecagdeletion mutant. Therefore, receptor protein and mRNA downregulation seem to be mediated by two independent mechanisms. Data obtained by immunohistochemistry suggested that downmodulation of CXCR1 and CXCR2 on neutrophils may also occur in vivo in the human stomach duringH. pyloriinfection. Downregulation of CXCR1 and CXCR2 expression on neutrophils inH. pyloriinfection byH. pyloriitself may represent a new mechanism of modulating neutrophil migration and activation in the gastric mucosa.