bluuebunny/crossref_metadata_2025_split huggingface dataset:
Arterial first pass gadolinium‐CM dynamics as a function of several intravenous saline flush and Gd volumes
Authors: Boos Matthias , Scheffler Klaus , Haselhorst R. , Reese Eva , Fröhlich J. , Bongartz Georg M. 
Published: August 2002

AbstractThis study was performed to evaluate the dynamics of an arterial first pass gadolinium (Gd) contrast medium (CM) bolus at the descending aorta (DAo), depending on various saline flush and Gd volumes. Using an ultra‐fast two‐ dimensional GE‐sequence (Siemens Vision®, 1.5‐T), 200 sequential cross‐sectional images of the addressed vessel (1 slice/s) were obtained. Several saline flush volumes (15 mL, 30 mL, and 60 mL) were applied following the administration of 10 mL Gd (single dose) to a group of 4 normal volunteers (body weight 50–55 kg) using a mechanical MR injector (injection rate = 3.0 mL/s). Additionally, when performing a second test series, the saline volume remained constant, while the Gd volumes were varied from half doses to triple doses (5, 10, 20, and 30 mL Gd were given to every volunteer of the group). The signal intensity versus time (SI/T) curve at a measured region of interest (ROI) within the DAo was calculated. The bolus arrival time (BAT), the maximal signal‐to‐noise ratio (SNRmax), the bolus time length (BL; 75% and 80% maximum intensity duration), the slope of the SI/T curve, and the areas below the SI/T curve for both the 80% and 75% maximum intensity duration level (INT80% and INT75%) were calculated. The increase of saline flush volume from 30 to 60 mL caused significant bolus lengthening of approximately 50% (mean BL = 9.5 s, 10.3 s, and 15.4 s for 15 mL, 30 mL, and 60 mL saline flush volumes, respectively, measured as SI/T duration at the 75% SNRmax level). Using saline flush volumes equal to or higher than 30 mL increased the slope of the SI/T curve. A continuous increase of INT75%/80% by using higher saline flush volumes was found. Different saline and Gd volumes did not affect the SNRmax and the BAT. Only the low dose (0.05 mmol/kg Gd) showed a 17%–21.6% significantly lower SNRmax. The BL and the INT increased mainly by enlarging of applied Gd volume from single to double dose (BL75% and INT75% were 9.6 s and 1305, 12.3 s and 2121, 38.5 s and 6181, 37.8 s and 6613 for 5, 10, 20, and 30 mL applied Gd volume, respectively). The arterial bolus length benefits from increasing Gd and saline flush volumes due to increased venous bolus length and wash out effects of Gd within the injection site of the vein. Doses larger than a single dose are not needed to increase the SNR in contrast‐enhanced magnetic resonance angiography images of the thoracic aorta. J. Magn. Reson. Imaging 2001;13:568–576. © 2001 Wiley‐Liss, Inc.
Pulmonary ventilation‐perfusion MR imaging in clinical patients
Authors: Nakagawa Toshio , Sakuma Hajime , Murashima Shuichi , Ishida Nanaka , Matsumura Kaname , Takeda Kan 
Published: August 2002

AbstractThe purpose of this study was to evaluate the feasibility of comprehensive magnetic resonance (MR) assessment of pulmonary perfusion and ventilation in patients. Both oxygen‐enhanced ventilation MR images and first‐pass contrast‐enhanced perfusion MR images were obtained in 16 patients with lung diseases, including pulmonary embolism, lung malignancy, and bulla. Inversion recovery single‐shot fast spin‐echo images were acquired before and after inhalation of 100% oxygen. The overall success rate of perfusion MR imaging and oxygen‐enhanced MR imaging was 94% and 80%, respectively. All patients with pulmonary embolism showed regional perfusion deficits without ventilation abnormality on ventilation‐perfusion MR imaging. The results of the current study indicate that ventilation‐perfusion MR imaging using oxygen inhalation and bolus injection of MR contrast medium is feasible for comprehensive assessment of pulmonary ventilation‐perfusion abnormalities in patients with lung diseases. J. Magn. Reson. Imaging 2001;14:419–424. © 2001 Wiley‐Liss, Inc.
Effect of body coil electric field distribution on receive‐only surface coil heating
Authors: Guclu C. Celil 
Published: August 2002

AbstractAlthough in the design of transmit RF coils, B1 homogeneity is crucial for good image quality, discussion of electric field (E‐field) distribution in the literature has been mostly limited to specific absorption rate (SAR) and patient loading (dielectric) effects. In this work, we report on a different aspect of E‐field: the receive‐only surface coil heating resulting from the voltage drop across the blocking (decoupling) networks and cable traps that are used to minimize the transmit field distortion. The results show that the z‐component (parallel to the coil cable) of the E‐field has a significant effect on the temperature rise in the surface coil. Therefore, in the receive‐only coil designs, it is not sufficient to consider only the induced voltage on the coil loop due to the B1 field, as is generally done in blocking network analysis calculations. The body coil E‐field distribution must be considered as well. J. Magn. Reson. Imaging 2001;14:484–487. © 2001 Wiley‐Liss, Inc.
Gas‐phase basicities for ions from bradykinin and its des‐arginine analogues
Authors: Ewing Nigel P. , Pallante Giovanni A. , Zhang Xin , Cassady Carolyn J. 
Published: August 2002

AbstractApparent gas‐phase basicities (GBapps) for [M + H]+ of bradykinin, des‐Arg1‐bradykinin and des‐Arg9‐bradykinin have been assigned by deprotonation reactions of [M + 2H]2+ in a Fourier transform ion cyclotron resonance mass spectrometer. With a GBapp of 225.8 ± 4.2 kcal mol−1, bradykinin [M + H]+ is the most basic of the ions studied. Ions from des‐Arg1‐bradykinin and des‐Arg9‐bradykinin have GBapp values of 222.8 ± 4.3 kcal mol−1 and 214.9 ± 2.3 kcal mol−1, respectively. One purpose of this work was to determine a suitable reaction efficiency ‘break point’ for assigning GBapp values to peptide ions using the bracketing method. An efficiency value of 0.1 (i.e. approximately 10% of all collisions resulting in a deprotonation reaction) was used to assign GBapps. Support for this criterion is provided by the fact that our GBapp values for des‐Arg1‐bradykinin and des‐Arg9‐bradykinin are identical, within experimental error, to literature values obtained using a modified kinetic method. However, the GBapps for bradykinin ions from the two studies differ by 10.3 kcal mol−1. The reason for this is not clear, but may involve conformation differences produced by experimental conditions. The results may be influenced by salt‐bridge conformers and/or by conformational changes caused by the use of a proton‐bound heterodimer in the kinetic method. Factors affecting the basicities of these peptide ions are also discussed, and molecular modeling is used to provide information on protonation sites and conformations. The presence of two highly basic arginine residues on bradykinin results in its high GBapp, while the basicity of des‐Arg1‐bradykinin ions is increased by the presence of two proline residues at the N‐terminus. The proline residue in the second position folds the peptide chain in a manner that increases intramolecular hydrogen bonding to the protonated N‐terminal amino group of the proline at the first position. Copyright © 2001 John Wiley & Sons, Ltd.
An intelligent data acquisition system for simultaneous screening of microsomal stability and metabolite profiling by liquid chromatography/mass spectrometry
Authors: Gu Ming , Lim Heng‐Keang 
Published: August 2002

AbstractThis paper describes the development of a mass spectrometer‐based, intelligent, programmable, sample‐selection data acquisition system with two unique features. One is that the system allows automatic determination of the mass to charge ratio (m/z) of an unknown compound and the utilization of the molecular ion information to perform selective ion monitoring (SIM) experiments for quantitation. The other is its decision‐making capability to select intelligently different samples and perform different experiments during data acquisition. These features were demonstrated by the application of the system to simultaneous screening for the microsomal stability and metabolite profiling of adatanserin. In this application, the data acquisition system continuously calculated the peak areas of adatanserin from SIM analyses of a batch of microsomal incubates stopped at various time points. Once the peak area of adatanserin had dropped to an arbitrarily predefined 60% of the initial value, the system made a decision to perform metabolite profiling of the sample. This decision initiated a series of automated operations, such as selecting a sample for re‐analysis, changing the data acquisition time and liquid chromatographic gradient and switching the SIM mode to the data‐dependent product ion scanning mode. The completed analysis of the batch of samples provided information both on the microsomal stability and on the metabolic profile of adatanserin. This simultaneous approach to investigating microsomal stability and metabolite profiling significantly increases the throughput for drug discovery support. Copyright © 2001 John Wiley & Sons, Ltd.
Prevalence of tick‐borne encephalitis virus in Ixodes ricinus ticks in Finland
Authors: Han Xiuqi , Aho Mika , Vene Sirkka , Peltomaa Miikka , Vaheri Antti , Vapalahti Olli 
Published: August 2002

AbstractApproximately 20 cases of tick‐borne encephalitis (TBE) occur annually in Finland. The known endemic areas are situated mainly in the archipelago and coastal regions of Finland, with highest incidence in Åland islands. Ixodes ricinus panels collected in 1996–1997 from two endemic areas were screened for the presence of RNA. Two distinct RT‐PCR methods were applied, and were shown to have an approximate detection limit of 10 focus forming doses (FFD)/100 μl. One out of 20 pools (a total of 139 ticks) from Helsinki Isosaari Island and one out of 48 pools (a total of 450 ticks) from Åland were positive with both methods, whereas the remaining pools were negative. The observed overall frequency (0.34%) in ticks in endemic areas of Finland, was similar to the low incidence found by virus isolation in mice in the 1960s (0.5%). Viral RNA was detectable in a diluted sample representing 0.005% of a positive pool of ten nymphs suggesting that the viral RNA load within an infected tick pool was approximately equivalent to 20,000–200,000 FFD. Sequence analysis did not show geographical clustering of the Finnish strains, suggesting an independent emergence of different TBE foci from the south. TBE virus RNA positive ticks were not found in I. ricinus panels consisting of 130 pools (726 ticks) from Helsinki city parks or 41 pools (197 ticks) from Võrmsi Island in Estonia. J. Med. Virol. 64:21–28, 2001. © 2001 Wiley‐Liss, Inc.
Identification of key mutations in HIV reverse transcriptase gene can influence the clinical outcome of HAART
Authors: Setti Maurizio , Bruzzone Bianca , Ansaldi Filippo , Borrelli Paolo , Indiveri Francesco , Icardi Giancarlo 
Published: August 2002

AbstractTherapeutic failures due to in vivo loss of drug sensitivity are still a major problem in AIDS care. Currently, the role of and methods for detecting resistant mutant strains in patients before therapeutic choices are still under debate. To investigate the relevance of screening for key mutations alone the commercial INNO‐LiPA HIV‐1 RT method was applied retrospectively to analyzing several HIV codons correlated with resistance to RTI (reverse‐transcriptase inhibitors) in sera from 62 patients before starting HAART protocols, selected on the basis of clinical parameters. INNO‐LiPA detected several resistant mutant strains, which were strictly consistent with previous selective pressure in the patients. A significant correlation between genotype pattern and response to HAART was found. The presence of key mutations associated with resistance to one or two RTI included in the protocol correlated with a decrease in treatment benefits, whereas patients with wild‐type or non‐resistant viral strains exhibited better response to HAART. Even if this information had been available when treatment was started, 45 of the patients would not have received different treatment. When compared with the total number of patients, the subgroup receiving a treatment that was considered retrospectively as consistent with the key mutation pattern exhibited a significantly better outcome. Although the interpretation of resistance‐related key mutations needs improvement, this surrogate LiPA method seems to maintain a predictive role in the management of HIV infection, and is less expensive. J. Med. Virol. 64:199–206, 2001. © 2001 Wiley‐Liss, Inc.
Full‐length genomic analysis of hepatitis B virus isolates in a patient progressing from hepatitis to hepatocellular carcinoma
Authors: Lin Xu , Qian Geng‐Sheng , Lu Pei‐Xing , Wu Li , Wen Yu‐Mei 
Published: August 2002

AbstractIn hepatitis B virus (HBV)‐endemic countries, the majority of hepatocellular carcinoma (HCC) arises in HBV carriers. High frequency of mutations at nucleotides 1762(A→T) and 1764(G→A) in the core promoter region have been described in HCC. Due to the differences in genetic backgrounds, environmental risk factors and random cellular insertion sites, it is difficult to analyze the possible roles of HBV variants detected in different HCC patients. In a follow‐up cohort study, an HBsAg‐positive asymptomatic carrier was diagnosed HCC within 4 years. Eleven full‐length HBV isolates, three from the first serum sample obtained 4 years pre‐HCC, and eight from serum sample, peri‐tumor and tumor tissue post‐HCC of this individual were sequenced and used to transfect HepG2 cells. When sequences were compared between pre‐ and post‐HCC isolates, no single mutation common to all post‐HCC isolates that differed from pre‐HCC isolates was found. Among all 11 isolates, there were 20 predicted amino acid substitutions shared by two or more post‐HCC isolates. These were located in the S(5), X(4), core(4), polymerase(4), pre‐S1(2) and pre‐S2(1) proteins. Possible roles of amino acid substitutions and enhanced replication efficiency in cells transfected by post‐HCC isolates are discussed. J. Med. Virol. 64:299–304, 2001. © 2001 Wiley‐Liss, Inc.
Acute self‐limiting hepatitis B after immunoprophylaxis failure in an infant
Authors: Komatsu Haruki , Fujisawa Tomoo , Sogo Tsuyoshi , Isozaki Atsushi , Inui Ayano , Sekine Isao , Kobata Makoto , Ogawa Yunosuke 
Published: August 2002

AbstractThe occurrence of acute hepatitis after failure of immunoprophylaxis in cases of mother‐to‐infant transmission of hepatitis B virus (HBV) is uncommon. Because immunoprophylaxis failure is caused by the emergence of an “a” determinant escape mutant, the infants usually become HBV carriers. To evaluate whether mutations in the S gene coding for the surface protein that contains the “a” determinant are associated with acute hepatitis after immunoprophylaxis failure, HBV DNA of an infant in with acute hepatitis developed with seroconversion to anti‐HBs antibodies at 12 months of age despite administration of anti‐hepatitis B immunoglobulin and hepatitis B vaccine was analyzed. The S gene from HBV DNA isolated from the serum of the infant at 12, 19, and 27 months of age was cloned and sequenced. Mutations affecting amino acid residues in the first loop within the “a” determinant (codons 124–147) were found at 12 months of age. Moreover, a novel deletion mutant, with a 1‐bp deletion at nucleotide 449 of the S gene, was found at 19 and 27 months of age. This deletion resulted in a frame shift and it introduced a stop codon (TAG) at codon 176. Because the open reading frame of the S gene is completely overlapped by the polymerase gene, mutations in the S gene may affect the polymerase gene. Based on this case, this study suggests that the observed frame‐shift mutation in the S gene might affect the polymerase protein and induce prompt suppression of viral replication. J. Med. Virol. 66:28–33, 2002. © 2002 Wiley‐Liss, Inc.
Molecular epidemiology of hepatitis B virus in Amsterdam 1992–1997*
Authors: van Steenbergen J.E. , Niesters H.G.M. , Op de Coul E.L.M. , van Doornum G.J.J. , Osterhaus A.D.M.E. , Leentvaar‐Kuijpers A. , Coutinho R.A. , van den Hoek J.A.R. 
Published: August 2002

AbstractTo gain insight into the spread of hepatitis B among various risk groups in Amsterdam a 6‐year (1992–1997) retrospective DNA sequencing study was carried out on isolates from stored sera from reported primary cases of acute hepatitis B infection. Cases were classified according to risk behavior, as determined in interviews. Of the available serum, a selected region of hepatitis B‐virus‐DNA was amplified and sequenced. The nucleotide alignments were subjected to phylogenetic tree analysis. When nucleotide alignments were subjected to phylogenetic analysis, the strains of 54 isolates, 26% of the 204 reported primary cases, clustered in five genotypes: A, C, D, E, and F. In genotype A, a cluster related to men having sex with men was identified. In genotype D, two subclusters could be identified: one was related to injecting drug use and another was related to the Moroccan population in Amsterdam. The remaining strains showed a high genetic variability within three different genotypes: F, E, and C. Of the 14 identical isolates in the “homosexual men cluster,” one was isolated from a female heterosexual. Of the 14 identical strains in the “drug users strain,” six were from non‐drug using heterosexual active individuals. In the cluster of twelve isolates related to hepatitis B‐endemic areas, probable modes of transmission were varied. Sequence analysis provides important insight into the spread of hepatitis B among various high‐risk groups. The analysis indicates that the prevention strategy in The Netherlands fails to stop transmission of hepatitis B from persistently infected individuals originating from hepatitis Bendemic countries. J. Med. Virol. 66:159–165, 2002. © 2002 Wiley‐Liss, Inc.
Genetic susceptibility to respiratory syncytial virus infection in inbred mice
Authors: Stark James M. , McDowell Susan A. , Koenigsknecht Vincent , Prows Daniel R. , Leikauf John E. , Le Vine Ann Marie , Leikauf George D. 
Published: August 2002

AbstractDifferences in the severity of respiratory syncytial virus (RSV)‐induced lower respiratory disease in infants have been attributed to multiple environmental and genetic factors. To identify the genetic factor(s) influencing RSV susceptibility, we examined RSV infection in eight inbred mouse strains. Lung RSV titers differed significantly between mouse strains: the RSV titers were 15‐fold higher in AKR/J (permissive) mice compared with C57BL/6J (resistant) mice at 4 days after inoculation. This strain‐specific difference in RSV titers suggested that susceptibility to RSV infection was attributable to genetic differences between strains. To examine the mode of inheritance of RSV susceptibility, F1 and backcross (F1 × AKR/J) progeny were infected and RSV titers determined. RSV titers in the F1 progeny were similar to those found in the resistant (C57BL/6J) parent, suggesting resistance was inherited as a dominant trait. The distribution of RSV titers in backcross progeny were discordant with that predicted for a single gene effect, suggesting susceptibility was influenced by more than one gene. These data suggest that RSV susceptibility is a multigenic trait that should be amenable to resolution by genomic analysis. J. Med. Virol. 67:92–100, 2002. © 2002 Wiley‐Liss, Inc.
On the suitability of GO/UTD modelling of microwave propagation in indoor environments
Authors: Torres R. P. , Valle L. , Domingo M. , Loredo S. 
Published: August 2002

AbstractThe main aim of this paper is to show the suitability of the geometrical optics and uniform theory of diffraction (GO/UTD) approach for modelling microwave propagation in indoor environments. Implementation details for an efficient method based on a combination of image theory and the binary space partitioning (BSP) algorithm to perform ray tracing are presented. The efficiency of the method allows a full three‐dimensional implementation of the GO/UTD approach. An extensive measurement champaign has been carried out in order to analyse the degree of accuracy achievable by the method. Some of these comparisons between measured and simulated data are presented, and a quantitative analysis of errors is made. The analysis reveals that the degree of precision in the calculation of the signal levels allows not only the signal mean level but also its statistics to be estimated accurately. The error in the mean level of the signal is less than 2 dB in the majority of cases, a maximum error of 3.6 dB having been obtained. The statistics of the signal fit Rice distributions very closely with different values of the rician parameterK. Finally, a brief study of the influence of the number of ray mechanisms considered (reflected, double reflected, etc.) on the accuracy and calculation times is also presented. Copyright © 2001 John Wiley & Sons, Ltd.
Differential postreceptor signaling events triggered by excitotoxic stimulation of different ionotropic glutamate receptors in retinal neurons
Authors: Santos Armanda E. , Carvalho Ana L. , Lopes Maria C. , Carvalho Arsélio P. 
Published: August 2002

AbstractThe aim of this work was to investigate whether excitotoxicity induced by overstimulation of different ionotropic glutamate receptors could trigger different intracellular signaling cascades. Cultured chick neuronal retina cells, essentially amacrine‐like, were particularly sensitive to the toxicity induced by non‐NMDA glutamate receptor agonists. One hour stimulation with 100 μM kainate induced a reduction of cell viability of about 44%, as assessed by the MTT test 24 hr after stimulation. Kainate‐induced toxicity was mediated through AMPA receptors. Glutamate (100 μM, 1 hr) reduced cell viability by 26%, essentially acting through N‐methyl‐D‐aspartate receptors. Five hours after stimulation, neuronal retina cells had an apoptotic‐like nuclear morphology. In retinal neurons, the excitotoxic stimulation, with either glutamate or kainate, induced a calcium‐dependent enhancement of the DNA‐binding activity of the activating protein‐1 (AP‐1) transcription factor, which was maximal 2 hr after stimulation. Glutamate induced a greater increase in the AP‐1 DNA‐binding activity than did kainate. Supershift assays using antibodies directed against different members of the Fos and Jun protein families showed that the AP‐1 complex in retinal neurons includes proteins of the Fos family, namely, Fra‐2, c‐Jun, and Jun D. The DNA‐binding activity of the nuclear factor‐κB transcription factor was not significantly changed upon excitotoxic stimulation with any agonist. Stimulation of glutamate receptors with 100 μM kainate or 100 μM glutamate for 2 min was sufficient to induce the activation of the extracellular signal‐regulated kinase (ERK). Inhibition of the ERK activation with the MEK inhibitors U 0126 and PD 98059 increased the toxicity induced by kainate but was without effect on the toxicity induced by glutamate. These results indicate that, although stimulation with both glutamate receptor agonists increased ERK phosphorylation, only kainate‐induced ERK activation correlates with the activation of a survival signaling pathway. Our results suggest that, in chick embryo retinal neurons, the signaling pathways that mediate excitotoxic cell death and neuroprotection are stimulus specific. J. Neurosci. Res. 66:643–655, 2001. © 2001 Wiley‐Liss, Inc.