bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simultaneous determination of Δ9‐tetrahydrocannabinol, 11‐hydroxy‐Δ9‐tetrahydrocannabinol and 11‐nor‐9‐carboxy‐ Δ9‐tetrahydrocannabinol in human plasma by high‐performance liquid chromatography/tandem mass spectrometry
Authors: Maralikova Barbora , Weinmann Wolfgang 
Published: April 2004

AbstractA rapid and sensitive method for the simultaneous confirmatory analysis of three forensic most relevant cannabinoids, Δ9‐tetrahydrocannabinol (THC), 11‐hydroxy‐Δ9‐tetrahydrocannabinol (11‐OH‐THC) and 11‐nor‐9‐carboxy‐Δ9‐tetrahydrocannabinol (THC‐COOH), by means of high‐performance liquid chromatography/tandem mass spectrometry (LC/MS/MS) in human plasma was developed and fully validated. Sample clean‐up was performed by automated silica‐based solid‐phase extraction and the separation was carried out using a PhenylHexyl column (50 × 2 mm i.d., 3 µm) and acetonitrile–5 mM ammonium acetate gradient elution. Data were acquired with an API 3000 LC/MS/MS system equipped with a turboionspray interface and triple quadrupole mass analyzer using positive electrospray ionization and multiple reaction monitoring. Two MS/MS transitions for each substance were monitored and deuterated analogues of analytes were used as internal standards for quantitation. The limit of quantitation was 0.8 ng ml−1 for THC, 0.8 ng ml−1 for 11‐OH‐THC and 4.3 ng ml−1 for THC‐COOH and linearity with a correlation coefficient r2 = 0.999 was achieved up to 100 ng ml−1 for THC and 11‐OH‐THC and 500 ng ml−1 for THC‐COOH. The limits of detection were 0.2 ng ml−1 for THC, 0.2 ng ml−1 for 11‐OH‐THC and 1.6 ng ml−1 for THC‐COOH. The developed LC/MS/MS method was also successfully used for the determination of THC‐COOH‐glucuronide, the phase II metabolite of THC‐COOH. Copyright © 2004 John Wiley & Sons, Ltd.
C6 cells express a sodium‐calcium exchanger/GM1 complex in the nuclear envelope but have no exchanger in the plasma membrane: Comparison to astrocytes
Authors: Xie Xin , Wu Gusheng , Ledeen Robert W. 
Published: April 2004

AbstractPrevious work demonstrated the presence of an isoform of Na+/Ca2+ exchanger in the nuclear envelope of neurons and NG108‐15 cells that is tightly associated with GM1 ganglioside and potentiated by the latter. This contrasted with the Na+/Ca2+ exchanger(s) in the plasma membrane, which were suggested to associate more loosely with GM1. To study these aspects of Na+/Ca2+ exchanger expression in nonneuronal neural cells, we have examined nuclear and plasma membrane exchanger patterns in astrocytes and C6 cells, a glia‐derived line. We find both cell types contain the tightly associated exchanger/GM1 complex in the nuclear envelope but, surprisingly, only astrocytes possess Na+/Ca2+ exchanger activity in the plasma membrane. This is the first reported example of a cell (C6) with Na+/Ca2+ exchangers in the nuclear envelope but not in the plasma membrane. RT‐PCR established the presence of the NCX1 subtype in C6 cells and both NCX1 and NCX2 in astrocytes. Comparison was made with NG108‐15 cells, which have Na+/Ca2+ exchangers in both nuclear and plasma membranes, and Jurkat cells, which have no Na+/Ca2+ exchanger in either membrane. Culturing of C6 cells in the presence dibutyryl‐cAMP caused upregulation of a high molecular weight isoform of the exchanger together with GM1 in the nuclear envelope, resulting in significant elevation of Na+/Ca2+ exchanger activity in the latter. Application of exogenous GM1 to nuclei from non‐treated cells also potentiated exchanger activity, although to a lesser degree. The Na+/Ca2+ exchanger/GM1 complex occurs in the inner membrane of the nuclear envelope, suggesting a functional role in transferring Ca2+ between nucleoplasm and the envelope lumen. © 2004 Wiley‐Liss, Inc.
γ‐Aminobutyric acid type B receptors facilitate L‐type and attenuate N‐type Ca2+ currents in isolated hippocampal neurons
Authors: Carter Thomas J. , Mynlieff Michelle 
Published: April 2004

AbstractActivation of presynaptic γ‐aminobutyric acid type B (GABAB) receptors inhibits neurotransmitter release at many synapses (both excitatory and inhibitory), and activation of postsynaptic GABAB receptors leads to a general inhibition of the postsynaptic cell in mature neurons. Although the action of GABAB receptors at the soma of excitatory hippocampal pyramidal cells has been resolved to be regulation of a potassium or calcium conductance, it is not clear that all neurons in the hippocampus demonstrate similar effects of GABAB receptor activation. In the current study, GABAB receptor‐mediated effects on calcium currents in acute cultures composed of heterogeneous cells from the superior region of neonatal hippocampi were studied. In 54.5% of cells, the GABAB receptor agonist baclofen (10 μM) attenuated the whole‐cell calcium current by 21.0% ± 1.1%. In 29.9% of cells, baclofen facilitated the calcium current by 43.5% ± 8.1%. The component of current attenuated by baclofen was blocked by the N‐type calcium channel antagonist ω‐conotoxin GVIA (3 μM). The component of current facilitated by baclofen was blocked by the L‐type channel antagonist nimodipine (20 μM). For cells that showed calcium current facilitation, baclofen shifted the half‐maximal activation by approximately –14 mV. The data indicate that activation of GABAB receptors in neurons of the superior hippocampus attenuates current through N‐type channels and facilitates current through L‐type channels. The two opposing effects of GABAB receptor activation may reflect the heterogeneity of the cultured cells or may be a developmentally regulated phenomenon. © 2004 Wiley‐Liss, Inc.
Hot‐stage Raman spectroscopic study of the thermal decomposition of saléeite
Authors: Frost Ray L. , Weier Matt L. 
Published: April 2004

AbstractHot‐stage Raman spectroscopy was used to study the changes in structure of the mineral saléeite, Mg(UO2)2(PO4)2·10H2O, during dehydration. Raman spectra were obtained using a Renishaw Raman microscope coupled with a Linkam thermal stage. Temperatures for Raman spectroscopic analysis were selected by studying the high‐resolution thermogravimetric analysis of saléeite. Five stages of dehydration are observed at 43, 73, 87, 231 and 376°C with the loss of 3, 3, 2, 1 and 1 mol of water, respectively. Three antisymmetric PO4 stretching vibrations are observed at 1007, 994 and 980 cm−1. No symmetric stretching vibration is observed until after significant dehydration has occurred at 75°C, when a low‐intensity band at 927 cm−1 is observed. Two bands at 843 and 827 cm−1 are attributed to the symmetric stretching modes of the two UO2 vibrational modes resulting from the two non‐equivalent UO bonds. The low‐intensity band at 894 cm−1 is assigned to the UO2 antisymmetric stretching mode. The complexity that is observed in the ν3 antisymmetric stretching region of the PO4 units is also observed in the PO4 ν2 bending region. Four bands are observed at 471, 446, 405 and 376 cm−1. Two bands observed at 283 and 234 cm−1 are assigned to the (UO2)2+ bending modes. After dehydration, it is suggested that the structure loses its distortion, takes on a tetragonal structure and hence the Raman spectra become less complex upon thermal treatment. Copyright © 2004 John Wiley & Sons, Ltd.
Performance evaluation of cylindrical fiber optic light diffusers for biomedical applications
Authors: Vesselov Leonid M. , Whittington William , Lilge Lothar 
Published: April 2004

AbstractBackground and ObjectivesDosimetry for intracavity and interstitial light delivery requires next to the knowledge of tissue optical properties and models describing light propagation in tissue also exact knowledge of the spatial light source emission characteristics. However, the emission characteristics of cylindrical diffusers are often ill defined by the manufacturer, and not regularly determined by the end user, thus limiting the attainable dosimetry accuracy.Study Design/Materials and MethodsCommercial cylindrical diffusers, with active diffusive lengths of 1–2 cm and outer diameters of ≤1 mm, were evaluated regarding their photometric emission characteristics. In addition to traditional tests of homogeneity such as light intensity emitted along the diffuser length and around its circumference (polar angle), azimuth emission was also measured.ResultsIt was demonstrated that the light emission distribution is specific to the diffuser manufacturer, and while good polar isotropy is often attained, azimuth isotropy can vary by more than a factor of 5. In hollow organs the latter can result in over treatment of tissue distal to the actual placement of the cylindrical diffusers.ConclusionsTo enable light dosimetry and treatment planning for applications such as photodynamic therapy or interstitial laser hyperthermia or photocoagulation, standardization of emission properties reporting for optical fiber diffusers is required. Lasers Surg. Med. 34:348–351, 2004. © 2004 Wiley‐Liss, Inc.
Determination of the dynamics of restored teeth by 3D electronic speckle pattern interferometry
Authors: Lang H. , Rampado M. , Müllejans R. , Raab W.H.‐M. 
Published: April 2004

AbstractBackground and ObjectivesThe difficulties typically encountered in studying the effects of restorations on tooth reinforcement are often due to the 3‐dimensional (3D) nature of deformation. Therefore, electronic 3D‐Speckle‐Interferometry (3D‐ESPI) was used to assess the impact of different restorative materials on the deformation of teeth.Study Design/Materials and MethodsSmall and large MOD‐preparations in extracted premolars were restored with gold inlays, ceramic inlays, composite resin inlays, amalgam, or composite resin. The restorations and cusps were loaded (90 N) and the deformation was assessed by 3D‐ESPI.ResultsTeeth with small restorations were deformed only slightly and the differences between the materials were minimal (P>0.05). In contrast, teeth with large restorations displayed material‐specific deformation patterns: (a) all materials led to decreased deformation as compared with unfilled teeth, (b) elastic materials caused only local deformation, (c) non‐adhesive materials resulted in translation of the restoration and marginal discrepancies, (d) adhesive inlays brought about increased deformation of the luting resin composite, (e) loading of the cusps caused higher deformation than loading of the restorations, and (f) bonded restorations stabilized the cusps.ConclusionsThe results show that the deformation pattern of restored teeth is material‐specific but the extent of deformation is primarily limited by the remaining tooth substance. Lasers Surg. Med. 34:300–309, 2004. © 2004 Wiley‐Liss, Inc.
Analysing absence behaviour using event history models
Authors: Barmby Tim , Sibly Suzyrman 
Published: March 2004

AbstractThis paper analyses the absence behaviour of a group of industrial workers. Part of their remuneration scheme comprises an experience rated sick‐pay scheme (linking level of sickpay to past absence) which determines the cost of a day's absence for a worker, both contemporaneously and in terms of expected future cost. This cost is explicitly computed for each worker and we show that this cost is negatively related to absence. Using an event history model with a Markov structure for the absence histories the size of this effect is shown to depend on the state occupied. Copyright © 2004 John Wiley & Sons, Ltd.
Endogenous R&D spillovers and locational choice with discriminatory pricing
Authors: Piga Claudio , Poyago‐Theotoky Joanna 
Published: March 2004

AbstractWe present a model of spatial price discrimination where R&D spillovers are endogenous as they depend on firms' location. We establish that both the distance between locations and R&D efforts are an increasing function of the transportation cost coefficient and show that there is a continuum of cases where firms will choose an intermediate location. The managerial implications from the model are discussed using examples of marketing behavior by Internet retailers. Copyright © 2004 John Wiley & Sons, Ltd.
Fixed cost, marginal cost, and the decision to buy or make
Authors: E. Hegji Charles 
Published: March 2004

AbstractThe paper builds a formal model of the costs and benefits of producing intermediate goods internally as compared to buying partially produced inputs on the open market. The model centers on the link between the purchase of assets specific to a production process and the mean and variance of profits from the purchase. The central point of the paper is that even though purchases of assets specific to a production process can have an ambiguous impact on profits of the decision to make, the purchase of such assets has a tendency to reduce the variability of profits. This trade‐off is at the heart of decision to buy or make. Copyright © 2004 John Wiley & Sons, Ltd.
Alliances and cost declaration
Authors: Gensemer Susan , Kanagaretnam Kiridaran 
Published: March 2004

AbstractOur model explores the co‐existence of both cooperative and competitive behaviors in an alliance setting. Specifically, when alliance partners cooperatively choose observable contributions given reported costs, their self‐interested behavior may lead to misreporting of costs related to these contributions.We show that truthful cost reporting by an alliance firm is valuable, thereby establishing that accurate cost reports are a determinant of successful alliance performance. Next we show that an alliance firm's cost reporting behavior may depend on the type of payoffs it receives from alliance, i.e., a share of profit or revenue, and also on the type of relationship between contributions, i.e., whether they are technical substitutes or complements. While we have focussed on highlighting factors which underlie cost misreporting, this study also may serve as a basis for investigating ways to design contracts to diminish the loss an alliance suffers from cost misreporting of the firms, thus increasing the chance that an alliance will be successful. Copyright © 2004 John Wiley & Sons, Ltd.
R&D spillovers and strategic delegation in oligopolistic contests
Authors: Kräkel Matthias 
Published: March 2004

AbstractConsidering oligopolistic contests with R&D spillovers and strategic delegation three results can be obtained: (1) There exist multiple asymmetric equilibria where one owner highly favors sales as a basis for his manager's incentives which drives the other firm out of the market. (2) If R&D spillovers are zero, a managerial firm will have a strong strategic advantage when competing with an entrepreneurial firm. If both owners endogenously decide about delegation, each owner's dominant strategy will be to delegate, given that the manager's reservation value is not too large. (3) If R&D spillovers are maximal, collusive market outcomes become very likely, which makes strategic delegation less important. Copyright © 2004 John Wiley & Sons, Ltd.
Causes and effects of multimarket activity from theory to empirical analysis
Authors: Vannoni Davide 
Published: March 2004

AbstractIn this paper some of the results emerged in the empirical literature on diversification are put into perspective against the background of a simple integrative model of multiproduct firms. By letting diversification strategies depend on the simultaneous play of four factors (demand relationships and technological links between goods, collusion within a market and across markets), the latter provides an illustrative framework which is useful to discuss how effectively the issue of ambiguous findings has been tackled in applied works. In some cases scholars have devoted substantial effort in order to build tests which can successfully discriminate among the different views on the causes and effects of diversification, while in other circumstances empirical investigations have been conducted with much less care. Other then criticising some of the methods used in the past, the paper provides a number of suggestions that can help guiding future empirical work on corporate diversification. Copyright © 2004 John Wiley & Sons, Ltd.
Neurotrophic activities of trk receptors conserved over 600 million years of evolution
Authors: Beck Gad , Munno David W. , Levy Zehava , Dissel Helga M. , van‐Minnen Jan , Syed Naweed I. , Fainzilber Mike 
Published: April 2004

AbstractThe trk family of receptor tyrosine kinases is crucial for neuronal survival in the vertebrate nervous system, however both C. elegans and Drosophila lack genes encoding trks or their ligands. The only invertebrate representative of this gene family identified to date is Ltrk from the mollusk Lymnaea. Did trophic functions of trk receptors originate early in evolution, or were they an innovation of the vertebrates? Here we show that the Ltrk gene conserves a similar exon/intron order as mammalian trk genes in the region encoding defined extracellular motifs, including one exon encoding a putative variant immunoglobulin‐like domain. Chimeric receptors containing the intracellular and transmembrane domains of Ltrk undergo ligand‐induced autophosphorylation followed by MAP kinase activation in transfected cells. The chimeras are internalized similarly to TrkA in PC12 cells, and their stimulation leads to differentiation and neurite extension. Knock‐down of endogenous Ltrk expression compromises outgrowth and survival of Lymnaea neurons cultured in CNS‐conditioned medium. Thus, Ltrk is required for neuronal survival, suggesting that trophic activities of the trk receptor family originated before the divergence of molluscan and vertebrate lineages approximately 600 million years ago. © 2004 Wiley Periodicals, Inc. J Neurobiol 60: 12–20, 2004
A comparative experiment in the consolidation of cremated bone
Authors: Rossi D. , De Gruchy S. , Lovell N. C. 
Published: March 2004

AbstractThis experiment assessed whether consolidation of cremated remains facilitated cross‐sectioning and grinding, which often are required for microstructural analyses such as the histomorphometric estimation of age and the examination of pathological lesions. Green, bovine femoral diaphyses were cremated at three temperature ranges (346–357°C; 610–755°C; 684–838°C) in an electric furnace and then consolidated with Acryloid B‐72 or Butvar B‐98 using simple brushing and immersion techniques. After consolidation was complete, bone pieces were cross‐sectioned and ground to a thickness of 100–120 μm. Results indicate that specimens treated with Acryloid B‐72 are harder and stronger than Butvar treated and untreated control specimens. Acryloid B‐72 is, therefore, recommended for the consolidation of cremated remains in preparation for microstructural analysis. Copyright © 2004 John Wiley & Sons, Ltd.
Inactivating mutation of the pro‐apoptotic gene BID in gastric cancer
Authors: Lee Jong Heun , Soung Young Hwa , Lee Jong Woo , Park Won Sang , Kim Su Young , Cho Yong Gu , Kim Chang Jae , Seo Si Hyung , Kim Hong Sug , Nam Suk Woo , Yoo Nam Jin , Lee Sug Hyung , Lee Jung Young 
Published: April 2004

AbstractThere is evidence that deregulation of apoptosis is mechanistically involved in cancer development and somatic mutations of apoptosis‐related genes have been reported in human cancers. BID, a pro‐apoptotic member of the Bcl‐2 family, interconnects the extrinsic apoptosis pathway initiated by death receptors to the intrinsic apoptosis pathway. To explore the possibility that genetic alterations of BID might be involved in the development of human cancers, this study analysed the entire coding region and all splice sites in the human BID gene in 67 advanced gastric carcinomas. Overall, four BID mutations (6.0%) were detected that consisted of one frameshift and three missense mutations. The tumour‐derived BID mutants were expressed in 293T cells and it was found that, compared with wild‐type BID, the frequency of apoptosis was significantly reduced in cells expressing the gene containing the frameshift mutation. Furthermore, expression of the inactivating frameshift mutant interfered with cell death by overexpression of death receptors, indicating that this mutant inhibits the extrinsic apoptosis pathway in a dominant‐negative fashion. Also, the frameshift mutation rendered cancer cells resistant to apoptosis induced by the anti‐cancer drug 5‐fluorouracil (5‐FU). This is the first report of BID gene mutation in human malignancy. The data suggest that such mutations occur rarely in gastric cancers and that only a small fraction of BID mutations may lead to the loss of its apoptotic function. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Natural history and long‐term outcome of cardiac rhabdomyomas detected prenatally
Authors: Fesslova Vlasta , Villa Laura , Rizzuti Tommaso , Mastrangelo Massimo , Mosca Fabio 
Published: March 2004

AbstractObjectivesTo analyse the data of fetal cases with rhabdomyomatosis, the growth of masses in utero, and the relative outcome.Material and MethodsThirteen cases of cardiac/pericardial tumours with characteristics suggesting rhabdomyomatosis were found in our centre on fetal echocardiography, five before 24 wg (group A) and eight (group B) at 25 to 36 wg. Four patients terminated the pregnancy, nine continued the pregnancy and were followed‐up until delivery and after birth (median postnatal follow‐up of 4.2 years, range 18 months–16 years).ResultsIn six/nine cases that continued the pregnancy (66.7%), the growth of smaller tumor masses was proportional with gestational age until 30 to 32 wg and was stable after that. In three cases, larger masses grew disproportionally and other small masses were revealed, causing a partial obstruction of outflow tracts. After birth, no case required surgery and no serious rhythm problems occurred. Cardiac masses regressed at least partially in all cases. Tuberous sclerosis was diagnosed in 9/11 cases (81.1%) investigated by magnetic resonance imaging in utero or postnatally. One case also had bilateral polycystic kidneys.ConclusionsMultiple and larger noduli progressed disproportionally in utero, until 30 to 36 wg. No relevant cardiac problems occurred after birth and the masses regressed in all cases. The high frequency of association with tuberous sclerosis is confirmed in our series. Copyright © 2004 John Wiley & Sons, Ltd.
Chorionic villus sampling (CVS) and fluorescence in situ hybridization (FISH) for a rapid first‐trimester prenatal diagnosis
Authors: Goumy Carole , Bonnet‐Dupeyron Marie‐Noëlle , Cherasse Yoan , Laurichesse Hélène , Jaffray Jean‐Yves , Lacroute Gisèle , Geneix Aimé , Lemery Didier , Vago Philippe 
Published: March 2004

AbstractObjectivesEarly diagnosis of unbalanced chromosomal abnormalities can be crucial in minimizing the trauma caused by an elective abortion. Chorionic villus sampling (CVS) can be performed from 9 weeks of gestation. However, two major problems are encountered in fetal karyotyping using cultured cells from chorionic villi: the relatively slow growth of these cells in culture, which delays the diagnosis, and the occurrence of maternal cell contamination (MCC). With FISH, a result can be obtained within 24 h, and, as no cell culturing is involved, the problem of MCC is minimized.MethodsThirty‐two women undergoing CVS between 9 and 12 weeks of gestation were offered FISH analysis in addition to the standard chromosome analysis.ResultsFISH was informative in all of the cases tested. Eleven aneuploidies were detected in cases of hygroma or abnormal nuchal translucency and two out of four fetuses from parental translocation were unbalanced. The decision to perform early termination of these chromosomally abnormal pregnancies was based on FISH results and ultrasound abnormalities, without waiting for karyotype results.ConclusionThe present study confirms that the association of FISH and CVS allows a rapid and early prenatal diagnosis, and emphasizes that this association is of great benefit in cases of known parental balanced translocation or when hygroma is detected by ultrasonography. Copyright © 2004 John Wiley & Sons, Ltd.