bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of hematopoietic bone marrow in male professional cyclists by magnetic resonance imaging of the lumbar spine
Authors: Altehoefer Carsten , Schmid Andreas , Büchert Martin , Ghanem Nadir A. , Heinrich Lothar , Langer Mathias 
Published: September 2002

AbstractPurposeTo prospectively evaluate hematopoietic bone marrow of male professional cyclists in relation to performance data and laboratory data, and in comparison to age‐matched healthy volunteers.Materials and MethodsTwenty male cyclists and 44 volunteers (27 males and 17 females) were prospectively studied by magnetic resonance imaging (MRI) at high‐field strength. A sagittal T1‐weighted (T1‐w) spin‐echo (SE) sequence, a gradient‐echo (GE) sequence with an echo time (TE) for out‐of‐phase (OOP) imaging, and a turbo inversion‐recovery sequence with short inversion time (TIRM) for fat suppression was used. The averaged bone marrow signal intensity (SI) of three adjacent vertebrae was related to the signal of an adjacent nondegenerative disk.ResultsThe cyclists revealed a significantly different SI as compared to male volunteers in the OOP (0.34 ± 0.14 vs. 0.28 ± 0.09, P < 0.05) and T1‐w sequences (1.62 ± 0.19 vs. 1.77 ± 0.30, P < 0.05). Only in TIRM was there a significant difference compared to female volunteers (0.36 ± 0.08 vs. 0.44 ± 0.04, P < 0.01). MRI data of cyclists did not correlate to hemoglobin, erythrocyte, or reticulocyte counts; ferritin, relative heart volume, relative maximal power (rPmax; W/kg bw), or relative maximal oxygen consumption (VO2max). A borderline linear correlation was found for hematocrit (OOP: r = 0.42, P = 0.06; TIRM: r = 0.44, P = 0.06).ConclusionBone marrow hyperplasia is observed in male professional cyclists in the axial skeleton. The MR findings are probably independent of mechanically induced marrow edema. A multifactorial cause must be considered, as single laboratory and performance data did not appear to contribute significantly to these results. J. Magn. Reson. Imaging 2002;16:284–288. © 2002 Wiley‐Liss, Inc.
Image‐guided surgery for anal fistula in a 0.5T interventional MRI unit
Authors: Gould S.W.T , Martin S. , Agarwal T. , Patel B. , Gedroyc W. , Darzi A. 
Published: September 2002

AbstractPurposeTo determine whether MR‐guided anorectal surgery is feasible, and to develop techniques for MR‐guided anal fistula surgery.Materials and MethodsSix patients with pilonidal sinus (PNS), and 21 with suspected anal fistulae were operated on in the GE Signa SPIO 0.5T interventional MRI unit. Procedures were performed with magnet‐safe Lockhart‐Mummery fistula probes. Preprocedural and intra‐operative MRI (IOMRI) techniques were used to identify the extent of the fistula tracts and septic foci, and to ensure the adequacy of the surgical procedure.ResultsIOMRI demonstrated the PNS lesions and the adequacy of excision. Imaging failed to demonstrate a fistula in two patients, as confirmed by surgical examination. No images were obtained in one patient due to his size (weight in excess of 100 kg). In 18 patients a fistula tract or abscess was demonstrated and IOMRI was used to assess the adequacy of the surgical procedure. In three patients this demonstrated incomplete drainage of septic foci, which was not obvious on inspection of the surgical field. We believe that in these patients IOMRI prevented an incomplete procedure and the potential requirement for a second operation. Further surgery was performed to rectify this situation. The fistula tract was laid open in 13 patients, and a Seton drain was inserted in five.ConclusionMRI‐guided surgery for anal fistula is feasible. IOMRI demonstrates the exact anatomy of the tracts and abscesses, and confirms that all have been adequately treated. We believe it may become particularly useful in surgery for recurrent and complex anal fistulae, and may lead to fewer recurrences. J. Magn. Reson. Imaging 2002;16:267–276. © 2002 Wiley‐Liss, Inc.
Estimation of left ventricular performance through temporal pressure variations measured by MR velocity and acceleration mappings
Authors: Tasu Jean‐Pierre , Mousseaux Elie , Colin Patrice , Slama Michel S. , Jolivet Odile , Bittoun Jacques 
Published: September 2002

AbstractPurposeTo describe a method for assessing pressure variation vs. time (dp/dt) using blood flow acceleration measured by MRI, and to demonstrate its applicability in estimating left ventricular (LV) function.Materials and MethodsThe method was tested in vitro using a pulsatile phantom, and a strong correlation was found between transducer and MRI determinations of dp/dt (r = 0.98). Selected aortic flow parameters were then measured in 10 patients and the results were compared with transducer measurements of the LV dp/dt.ResultsThe correlation coefficients for the reference estimations of global myocardial function and MRI were 0.59 for aortic velocity, 0.74 for aortic acceleration, and 0.86 for aortic dp/dt.ConclusionMR measurements of velocity and acceleration within the ascending aorta offer a noninvasive method for determining indices, such as the aortic dp/dt, that are closely correlated with the global myocardial contractility function. J. Magn. Reson. Imaging 2002;16:246–252. © 2002 Wiley‐Liss, Inc.
Comparison of automated and manual MRI volumetry of hippocampus in normal aging and dementia
Authors: Hsu Yuan‐Yu , Schuff Norbert , Du An‐Tao , Mark Kevin , Zhu Xiaoping , Hardin Dawn , Weiner Michael W. 
Published: September 2002

AbstractPurposeTo determine whether automatic and manual measurements of hippocampal volume differences on MRI between normal aging, cognitive impairment (CI), and Alzheimer's disease (AD) yield similar results.Materials and MethodsReliability was determined for an automatic and a manual method on nine volunteers (22–83 years old) who underwent MRI twice in 1 day. Hippocampal volumes of 20 cognitively normal subjects (mean age 74.0 ± 6.2 years) and age‐matched patients (20 CI and 20 AD) were compared.ResultsThe intraclass correlation for automatic calculations of hippocampal volume was 0.94; for manual tracing it was 0.99. Volume differences between cognitively normal, CI, and AD subjects from the automatic and manual methods were similar.ConclusionBecause the automatic calculations were faster and less susceptible to rater bias than manual tracing, this automated method is expected to be very useful for analyzing hippocampal changes in studies of aging and dementia. J. Magn. Reson. Imaging 2002;16:305–310. Published 2002 Wiley‐Liss, Inc.
Comparison of right ventricular volume measurement between segmented k‐space gradient‐echo and steady‐state free precession magnetic resonance imaging
Authors: Alfakih Khaled , Thiele Holger , Plein Sven , Bainbridge Gavin J. , Ridgway John P. , Sivananthan Mohan U. 
Published: September 2002

AbstractPurposeTo compare right ventricular volume measurements and their reproducibility between steady‐state free precession (SSFP) and conventional turbo gradient‐echo (TGE) imaging.Materials and MethodsRight ventricular volumes and observer variabilities were compared between SSFP and TGE in 31 subjects (21 normal volunteers and 10 subjects with heart failure). For further internal validation of the right ventricular volumes, the left ventricle (LV) and right ventricle (RV) stroke volumes were compared for the normal volunteers.ResultsThe volumes as measured by SSFP were significantly larger than for TGE (mean bias end‐diastolic volume [EDV] 11.1 ± 14.2, end‐systolic volume [ESV] 9.8 ± 9.75). SSFP had lower interobserver variability (SSFP EDV −10.1 ± 11.6 vs. TGE EDV −6.2 ± 18.5) and intra‐observer variability (SSFP EDV −2.0 ± 6.3 vs. TGE EDV −6.1 ± 14.8). The mean absolute differences between LV and RV stroke volumes for 21 normal volunteers were: TGE 5.8 ± 12.9 (r2 = 0.72), SSFP 4.6 ± 6.9 (r2 = 0.92).ConclusionSSFP and TGE yield different measurement values of RV volumes with SSFP, providing a more reproducible measurement. J. Magn. Reson. Imaging 2002;16:253–258. © 2002 Wiley‐Liss, Inc.
Interaction of Cu+ and Cu2+ ions with α‐alanine. A density functional study
Authors: Marino Tiziana , Russo Nino , Toscano Marirosa 
Published: September 2002

AbstractThe Cu+ and Cu2+ preferred binding sites on α‐alanine and their affinity values for this amino acid were determined at the density functional level using three different hybrid exchange correlation potentials and the 6–311++G** basis set. The results demonstrated that the two ions both give stable complexes with α‐alanine but the stability order of the metalated species and the coordination sites are different depending on the nature of the cation. In particular, the Cu+–α‐alanine ground‐state structure is characterized by an η2‐N,O coordination with the nitrogen and oxygen atoms belonging to the amino and carbonyl groups, respectively. In contrast, the most stable complex of the Cu2+–α‐alanine system has an η2‐O,O coordination with the cation bonded to the —CO2− moiety of the zwitterionic form of the amino acid. Comparison with the Cu+ and Cu2+ affinity values for glycine, computed at the same levels of theory, demonstrated that the relative values do not change significantly as different hybrid functionals are used, although the absolute affinities are strongly influenced by the choice of the hybrid potential. Copyright © 2002 John Wiley & Sons, Ltd.
Multistep mass spectrometry of heterocyclic amines in a quadrupole ion trap mass analyser
Authors: Toribio Francisca , Moyano Encarnación , Puignou Lluís , Galceran Maria Teresa 
Published: September 2002

AbstractThe fragmentation of heterocyclic amines (HAs) in an ion trap was studied by means of the infusion of methanolic solutions containing the compounds under assay, and using an atmospheric pressure chemical ionization (APCI) as ion source. The MSn spectra obtained for compounds included in the same family, either aminoimidazoazaarenes (AIAs) or carbolines, were compared in order to propose fragmentation pathways for each HA. Moreover, labelled AIAs were used to establish the mechanisms. The protonated molecule was always obtained, but subsequent fragmentation was different for both families. In the case of AIAs, major product ions came from the fragmentation of the aminoimidazole moiety, thus the base peak in MS2 corresponded to the loss of the methyl group, and losses of C2NH3 and CN2H2 were also observed. Further fragmentation occurred in the heterocyclic rings, mainly with losses of HCN and CH3CN. For carbolines, the most important product ions came from the loss of ammonia, except for harman and norharman, the loss of a methyl group for methylated carbolines or the loss of diverse fragments from the heterocyclic rings. In some cases, ion–molecule reactions into the ion trap were observed. For instance, for AαC or MeAαC one ion originating from these reactions corresponded to the base peak. Copyright © 2002 John Wiley & Sons, Ltd.
Lactone enol cation‐radicals: gas‐phase generation, structure, energetics, and reactivity of the ionized enol of butane‐4‐lactone
Authors: Tureček František , Vivekananda Shetty , Sadílek Martin , Polášek Miroslav 
Published: September 2002

AbstractThe cation‐radical of 2‐hydroxyoxol‐2‐ene (1+·) represents the first lactone enol ion whose structure and gas‐phase ion chemistry have been studied by experiment and theory. Ion 1+· was generated by the McLafferty rearrangement in ionized 2‐acetylbutane‐4‐lactone and characterized by accurate mass measurements, isotope labeling, metastable ion and collisionally activated dissociation (CAD) spectra. Metastable 1+· undergoes competitive losses of H‐4 and CO that show interesting deuterium and 13C isotope effects. The elimination of CO from metastable 1+· shows a bimodal distribution of kinetic energy release and produces ·CH2CH2CHOH+ (14+·) and CH3CHCHOH+· (15+·) in ratios which are subject to deuterium isotope effects. Ab initio calculations at the G2(MP2) level of theory show that 1+· is 105 kJ mol−1 more stable than its oxo form, [butane‐4‐lactone]+·(2+·). The elimination of CO from 1+· involves multiple isomerizations by hydrogen migrations and proceeds through ion–molecule complexes of CO with 14+· and 15+·. In addition, CO is calculated to catalyze an exothermic isomerization 14+· → 15+· in the ion–molecule complexes. Multiple consecutive hydrogen migrations in metastable 1+·, as modeled by RRKM calculations on the G2(MP2) potential energy surface, explain the unusual deuterium kinetic isotope effects on the CO elimination. Copyright © 2002 John Wiley & Sons, Ltd.
Determination of ivermectin B1a in animal plasma by liquid chromatography combined with electrospray ionization mass spectrometry
Authors: Croubels S. , De Baere S. , Cherlet M. , De Backer P. 
Published: September 2002

AbstractA novel, sensitive and specific method for the quantitative determination of ivermectin B1a in animal plasma using liquid chromatography combined with positive electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS) is presented. Abamectin was used as the internal standard. Extraction of the samples was performed with a deproteinization step using acetonitrile. Chromatographic separation was achieved on a Nucleosil ODS 5 µm column, using gradient elution with 0.2% (v/v) acetic acid in water and 0.2% (v/v) acetic acid in acetonitrile. The method was validated according to the requirements defined by the European Community. Calibration curves using plasma fortified between 1 and 100 ng ml−1 showed a good linear correlation (r ≥ 0.9989, goodness‐of‐fit coefficient ≤8.1%). The trueness at 2 and 25 ng ml−1 (n = 6) was +4.2 and −17.1%, respectively. The trueness and between‐run precision for the analysis of quality control samples at 25 ng ml−1 was −4.0 and 11.0%, respectively (n = 16). The limit of quantification of the method was 1.0 ng ml−1, for which the trueness and precision also fell within acceptable limits. Using a signal‐to‐noise ratio of 3 : 1, the limit of detection was calculated to be 0.2 ng ml−1. The specificity was demonstrated with respect to ivermectin B1b.The method was successfully used for the quantitative determination of ivermectin B1a in plasma samples from treated bovines, demonstrating the usefulness of the developed method for application in the field of pharmacokinetics. Copyright © 2002 John Wiley & Sons, Ltd.
New results on the dissociative photoionization of CF4 and CCl4
Authors: Kinugawa T. , Hikosaka Y. , Hodgekins A. M. , Eland J. H. D. 
Published: September 2002

AbstractUsing the VIPCO technique, we remeasured and completed the breakdown diagram of CCl4+ up to 21 eV energy. The angle‐resolved data show both orientation and alignment of photoelectrons relative to CX3+ fragments from photoionization to the low‐lying states of CF4+ and CCl4+. The strength of the orientation (forward/backward asymmetry) is surprising in view of the nearly spherical symmetry of the parent molecules, and calls for theoretical explanation. It may indicate that nuclear and electron motion take place on similar time‐scales. Copyright © 2002 John Wiley & Sons, Ltd.
A quantitative model of ultraviolet matrix‐assisted laser desorption/ionization
Authors: Knochenmuss R. 
Published: September 2002

AbstractA quantitative model of primary ionization in ultraviolet matrix‐assisted laser desorption/ionization (UV‐MALDI) is presented. It includes not only photochemical processes such as exciton pooling, but also the effects of the desorption event. The interplay of these two is found to be a crucial aspect of the MALDI process. The desorbing plume is modeled as an adiabatic expansion with entrained clusters. The parameters in the model are defined as much as possible via experiment or by analogy with known effects. The model was applied to the matrix 2,5‐dihydroxybenzoic acid and found to reproduce the fluence dependence of the fluorescence yield and key features of the picosecond two‐pulse ion generation efficiency curves. In addition, the model correctly predicts a fluence rather than irradiance threshold, the magnitude of the threshold, the magnitude of the ion yield, laser wavelength effects, plume temperatures, plume expansion velocities and the spot size effect. Copyright © 2002 John Wiley & Sons, Ltd.
Long‐term lithium treatment prevents neurotoxic effects of β‐bungarotoxin in primary cultured neurons
Authors: Tseng Wen‐Pei , Lin‐Shiau Shoei‐Yn 
Published: September 2002

AbstractLithium is the most commonly used drug for the treatment of manic‐depressive illness. The precise mechanisms underlying its clinical efficacy remain unknown. In this study, we found that long‐term exposure to lithium chloride protected cultured cerebellar granule neurons (CGNs) against β‐bungarotoxin (β‐BuTX)‐induced neurotoxicity. This neuroprotection was exhibited at the therapeutically relevant concentration of 1.2 mM lithium. Pretreatments for 3–5 days (long‐term) were required for protection to occur; but a 3 hr treatment (short‐term) was ineffective. In contrast, a longer treatment for 6–7 days or a higher concentration of 3 mM lithium led not only to loss of the neuroprotective effect but also to a neurotoxic effect. These findings suggest that lithium protection is limited to its narrow window of concentration and apparently relevant to its narrow therapeutic index in clinical application. Measurement of intracellular calcium [Ca2+]i revealed that neurotoxic concentrations of β‐BuTX markedly increased [Ca2+]i, which could be attenuated by long‐term, but not short‐term, lithium treatment. Thus, the protection induced by lithium in CGNs was attributed to its inhibition of calcium overload. In addition, the Ca2+ signaling pathway, including reactive oxygen species production and mitochondrial membrane potential reduction, along with the neurotoxic effect of β‐BuTX was blocked by long‐term, but not short‐term, lithium treatment. All of these results indicate that a crucial step for lithium protection is modulation of [Ca2+]i homeostasis and that lithium neurotoxicity possibly, at least in part, is due to calcium overload. In conclusion, our results suggest that lithium, in addition to its use in treatment of bipolar depressive illness, may have an expanded use in intervention for neurotoxicity. © 2002 Wiley‐Liss, Inc.
Two separate domains in the golli myelin basic proteins are responsible for nuclear targeting and process extension in transfected cells
Authors: Reyes Samuel D. , Campagnoni Anthony T. 
Published: September 2002

AbstractThe golli products of the myelin basic protein (MBP) gene are expressed in neurons and oligodendrocytes (OLs). In certain neuronal populations, golli proteins undergo translocation between the nucleus and cytoplasm/processes during development. The proteins consist of two domains, a golli domain of 133 amino acids and an MBP domain of variable length. One objective of this study was to identify the sequences responsible for nuclear targeting. Site‐directed mutagenesis and deletion analyses were used to generate a series of golli‐green fluorescent protein (GFP) DNA constructs that were transfected into OL and neuronal cell lines to follow localization by confocal microscopy. The results indicated that a 36‐residue stretch in the MBP domain is essential for nuclear targeting, and the sequence appears to be a nontraditional localization signal motif. The studies also revealed that overexpression of golli proteins could induce dramatic changes in cell morphology. In OL lines, overexpression of intact golli proteins, or golli peptide alone, caused an increase in the length and number of processes, and the elaboration of membrane sheets. In the neuronal lines, there was a dramatic increase in number and length of extensions. The results, consistent with the timing of golli expression in cells during neural development, suggest that golli proteins may be involved in process formation/extension in OLs and neurons during development. These studies have defined two functional domains in the golli protein. Sequences in the MBP domain target the protein into the nucleus and sequences within the golli domain induce process sheet extension in OLs and neurons. © 2002 Wiley‐Liss, Inc.
Postnatal development of 11β‐hydroxysteroid dehydrogenase type 1 in the rat hippocampus
Authors: Wan S.L. , Liao M.Y. , Sun K. 
Published: September 2002

AbstractGlucocorticoids (GCs) have important actions in the hippocampus of the brain, where their access to glucocorticoid receptor (GR) is increased by 11β‐hydroxysteroid dehydrogenase type 1 (11β‐HSD1). 11β‐HSD1 converts biologically inactive 11‐dehydrocorticosterone into active corticosterone. However, the postnatal development of 11β‐HSD1 in the hippocampus is not properly understood. In this study, the postnatal distribution and development of 11β‐HSD1 in the hippocampus of the rat brain was studied with immunohistochemistry and Western blot analysis. Results showed that abundant 11β‐HSD1 immunoreactive substance (ir‐11β‐HSD1) was present in the hippocampus. There were homogeneous distributions of 11β‐HSD1 in the hippocampal CA1, CA2, CA3, CA4 regions and the dentate gyrus at postnatal days 1, 3, and 7. Interestingly, the developmental distribution of GR in the hippocampus followed the same pattern as 11β‐HSD1. Western blot analysis demonstrated that a higher level of expression of 11β‐HSD1 in the hippocampus was found in the first 2 weeks of life. The expressions of 11β‐HSD1 started to drop to adult levels at about postnatal day 15 both in the hippocampus and in other brain areas. These results suggest that the higher expression of 11β‐HSD1 in the neonatal hippocampus may be important for the maturation of the central nervous system mediated by GCs through GR. © 2002 Wiley‐Liss, Inc.
Paradigm shifts in Alzheimer's disease and other neurodegenerative disorders: The emerging role of oligomeric assemblies
Authors: Kirkitadze Marina D. , Bitan Gal , Teplow David B. 
Published: September 2002

AbstractAlzheimer's disease (AD) is a progressive, neurodegenerative disorder characterized by amyloid deposition in the cerebral neuropil and vasculature. These amyloid deposits comprise predominantly fragments and full‐length (40 or 42 residue) forms of the amyloid β‐protein (Aβ) organized into fibrillar assemblies. Compelling evidence indicates that factors that increase overall Aβ production or the ratio of longer to shorter forms, or which facilitate deposition or inhibit elimination of amyloid deposits, cause AD or are risk factors for the disease. In vitro studies have demonstrated that fibrillar Aβ has potent neurotoxic effects on cultured neurons. In vivo experiments in non‐human primates have demonstrated that Aβ fibrils directly cause pathologic changes, including tau hyperphosphorylation. In concert with histologic studies revealing a lack of tissue injury in areas of the neuropil in which non‐fibrillar deposits were found, these data suggested that fibril assembly was a prerequisite for Aβ‐mediated neurotoxicity in vivo. Recently, however, both in vitro and in vivo studies have revealed that soluble, oligomeric forms of Aβ also have potent neurotoxic activities, and in fact, may be the proximate effectors of the neuronal injury and death occurring in AD. A paradigm shift is thus emerging that necessitates the reevaluation of the relative importance of polymeric (fibrillar) vs. oligomeric assemblies in the pathobiology of AD. In addition to AD, an increasing number of neurodegenerative disorders, including Parkinson's disease, familial British dementia, familial amyloid polyneuropathy, amyotrophic lateral sclerosis, and prion diseases, are associated with abnormal protein assembly processes. The archetypal features of the assembly‐dependent neuropathogenetic effects of Aβ may thus be of relevance not only to AD but to these other disorders as well. © 2002 Wiley‐Liss, Inc.