bluuebunny/crossref_metadata_2025_split huggingface dataset:
Magnetic resonance imaging of atherosclerotic plaques using superparamagnetic iron oxide particles
Authors: Schmitz Stephan A. , Taupitz Matthias , Wagner Susanne , Wolf Karl‐Jürgen , Beyersdorff Dirk , Hamm Bernd 
Published: August 2002

AbstractExperimental data show accumulation of superparamagnetic iron oxide (SPIO) particles in atherosclerotic plaques. SPIO uptake occurred in plaques, suggesting an increased endothelial permeability and macrophage infiltrates as signs of inflammatory plaque activity. We incidentally observed SPIO uptake in aortic and arterial wall segments in patients who had originally received the magnetic resonance (MR) contrast agent for staging lymph node metastases. Twenty patients (19 male, 1 female; mean age, 64; range, 41–78 years) with bladder or prostate cancer underwent MR imaging (MRI) using a T2*‐weighted high‐resolution gradient‐echo sequence prior to and 24–36 hours after intravenous injection of 2.6 mg of Fe/kg of SPIO (Sinerem®). The aorta, both common external and internal iliac, as well as both superficial femoral arteries, were retrospectively analyzed for atherosclerotic wall changes. One patient was excluded. A positive finding was defined as an area of pronounced signal loss on postcontrast images clearly confined to the arterial wall, which was absent in the precontrast examination or increased in size. Such a finding was observed in one to three arteries in 7 of the 19 patients. The pronounced signal loss in the wall of the aorta and pelvic arteries seen in part of an elderly patient population after intravenous SPIO administration strongly suggests that this contrast agent accumulates in human atherosclerotic plaques. J. Magn. Reson. Imaging 2001;14:355–361. © 2001 Wiley‐Liss, Inc.
Transvascular and interstitial transport of a 19 kDa linear molecule in human melanoma xenografts measured by contrast‐enhanced magnetic resonance imaging
Authors: Bjørnæs Ingvil , Rofstad Einar K. 
Published: August 2002

AbstractCancer therapy involving blood‐borne macromolecular therapeutic agents often fails, owing to inadequate macromolecule uptake in malignant tissue. The transvascular and interstitial transport of a 19 kDa linear molecule (NC22181 or poly‐[Gd‐DTPA]‐co‐[1,6‐diaminohexane]) was studied in the present work in an attempt to identify transport barriers limiting the delivery of macromolecules to tumors. Tumors of four human melanoma xenograft lines were included in the study. The uptake of NC22181 was measured by spoiled gradient recalled magnetic resonance imaging (MRI). The effective microvascular permeability constant and the interstitial influx constant of NC22181 were calculated from NC22181 uptake curves by using a three‐compartment tissue model. The uptake of NC22181 was limited by the interstitial transport and not by thetransvascular transport in all xenograft lines. If the melanoma xenografts used in this study are representative models of human cancer, our results suggest that strategies for increasing the delivery of macromolecular therapeutic agents to tumors should focus on improving the transport conditions in the interstitium, rather than enhancing the permeability of the microvascular wall. J. Magn. Reson. Imaging 2001;14:608–616. © 2001 Wiley‐Liss, Inc.
Minimizing analyte electrolysis in an electrospray emitter
Authors: Kertesz Vilmos , Van Berkel Gary J. 
Published: August 2002

AbstractThe electrospray (ES) ion source is a controlled‐current electrolytic flow cell. Electrolytic reactions in the ES emitter capillary are continually ongoing to sustain the production of charged droplets and ultimately gas‐phase ions from this device. Under certain circumstances, the analytes under study may be directly involved in these electrolytic processes. It is demonstrated that a simple means to minimize analyte electrolysis is to exchange the normal metal emitter capillary of commercial ES sources with one made of fused silica. This change is shown to provide an ES mass spectrometric system of similar performance in terms of gas‐phase ion signal generated for non‐electroactive analytes and also assures minimal oxidation of electroactive analytes even at low (2.0 µl min−1) solution flow‐rates and high (millimolar) solution electrolyte concentrations. Published in 2001 by John Wiley & Sons, Ltd.
Matrix‐assisted laser desorption/ionization Fourier transform mass spectrometric analysis of oxygenated triglycerides and phosphatidylcholines in egg tempera paint dosimeters used for environmental monitoring of museum display conditions
Authors: van den Brink Oscar F. , Boon Jaap J. , O'Connor Peter B. , Duursma Marc C. , Heeren Ron M. A. 
Published: August 2002

AbstractOxidative changes in triacylglycerols and diacylphosphatidylcholines in egg tempera paint strips are used for chemical dosimetry of the quality of the museum environment. High‐resolution matrix‐assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI‐FTMS) was used as a rapid method for the determination of the exact elemental composition of the alteration products from diacylphosphatidylcholines and triacylglycerols. Light exposure of the egg tempera paints yields oxygenated diacylphosphatidylcholines and triacylglycerols. In the latter multiple incorporation of oxygen was observed as a recurring mass difference of 15.995, the exact atomic mass of oxygen. Owing to the high resolution of the FTMS data (routinely 20 000 at m/z 1000 in broadband mode), oxidation products with different elemental compositions but identical nominal mass could be distinguished. Products of oxidative cleavage of triacylglycerols were observed in samples exposed for longer times. The relative intensities of the peaks of singly and multiply oxygenated triacylglycerols were used to derive the degree of oxygenation of the egg lipids in the tempera paint dosimeters. The degree of oxygenation was found to be directly related to the light exposure time. Exposure to elevated temperature (60 °C) for a period of 21 days did not lead to oxygenation of the triacylglycerols and diacylphosphatidylcholines. Exposure to NOx and SO2 in the dark greatly increased the degree of oxygenation. Addition of lead‐ or copper‐containing pigments to the egg binding medium (and subsequent storage for 6 months in the dark) led to accelerated conversion of egg lipids to oxidised products. Copyright © 2001 John Wiley & Sons, Ltd.
Characterization and differentiation of ruthenium(II) complexes with 1,4,7‐trithiacyclononane and nitrogen heterocycles by electrospray mass spectrometry
Authors: Santana‐Marques M. Graça O. , Amado Francisco M. L. , Correia A. J. Ferrer , Lucena Mónica , Madureira João , Goodfellow Brian J. , Félix Vítor , Santos Teresa M. 
Published: August 2002

AbstractElectrospray ionization mass spectrometry (ESIMS) was used to characterize a series of new ruthenium(II) complexes with several nitrogen heterocycles and a common ligand: the crown thioether 1,4,7‐trithiacyclononane, [9]aneS3. ESIMS allows the easy identification of the [RuIICl([9]aneS3)Y]X complexes, where Y is a bidentate nitrogen heterocycle and X is Cl− or PF6−, through the formation of two diagnostic ions by fragmentation of the common ligand [9]aneS3. Structures for these ions and mechanisms for their gas‐phase formation are proposed based on data from product ion spectra. Copyright © 2001 John Wiley & Sons, Ltd.
Determination of RSD921 in human plasma by high‐performance liquid chromatography–tandem mass spectrometry using tri‐deuterated RSD921 as internal standard: application to a phase I clinical trial
Authors: Ribeiro Wellington , Ifa Demian R , Corso Gaetano , Salmon John , Moraes Leonardo A. , Eberlin Marcos N. , Nucci Gilberto de 
Published: August 2002

AbstractA fast, sensitive and specific method is presented for the quantification of RSD921 in human plasma by liquid chromatography coupled with tandem mass spectrometry using tri‐deuterated RSD921 (3d‐RSD921) as an internal standard. A single‐step liquid/liquid extraction was performed with diethyl ether/hexane (80 : 20, v/v) using 0.5 ml of plasma. The plasma calibration curves were linear from 0.1 to 20 ng ml−1 (r > 0.999). Between‐run precision, based on the percent relative deviation for replicate (n = 40) quality controls, was ≤7.27% (0.5 ng ml−1), ≤7.39% (5.0 ng ml−1), and ≤5.06% (20.0 ng ml−1). Between‐run accuracies, based on the relative error, were ±2.59%, ±1.23% and ±1.64% respectively. The method was developed to evaluate the pharmacokinetic profile after 15 min of intravenous stepwise‐ascending infusion dose of RSD921 in 18 healthy volunteers. A dissociation study of protonated RSD921 and 3d‐RSD921 by collision‐induced dissociation using in‐source fragmentation and tandem mass spectrometry is also presented. Copyright © 2001 John Wiley & Sons, Ltd.
Integration of mass spectrometry into early‐phase discovery and development of central nervous system agents
Authors: Prokai Laszlo , Zharikova Alevtina , Janáky Tamás , Li Xiaoxu , Braddy April C. , Perjési Pál , Matveeva Lidia , Powell David H. , Prokai‐Tatrai Katalin 
Published: August 2002

AbstractThe early‐phase discovery and development of useful central nervous system (CNS) agents present ample opportunities to exploit mass spectrometry and provide detailed compound/mixture characterization, or to make the process faster and/or more economic. Neuropeptide FF antagonists and centrally active thyrotropin‐releasing hormone analogues were used as specific examples in this work. We evaluated the characterization of focused libraries of peptide derivatives by electrospray ionization, tandem mass spectrometry and liquid chromatography/tandem mass spectrometry on a quadrupole ion trap and nanoelectrospray on a Fourier transform ion cyclotron resonance mass spectrometer. Immobilized artificial‐membrane chromatography was employed as a model to predict/rank new agents against lead compounds for their potential to reach the central nervous system in pharmacologically significant amounts. Measuring brain concentrations in rodents after the intravenous administration of test compounds was used as an in vivo approach, and we took advantage of microdialysis sampling that furnished samples without interfering tissue matrix and afforded the estimation of extracellular concentrations in a localized part of the brain. Overall, making atmospheric‐pressure ionization mass spectrometry an integral part of the process has played a major role in increasing throughput, selectivity, specificity and detection sensitivity and thereby providing useful information about the extent or mechanism of transport and metabolic activation/inactivation in early‐phase discovery and development of CNS agents. Copyright © 2001 John Wiley & Sons, Ltd.
Fragmentation study of rutin, a naturally occurring flavone glycoside cationized with different alkali metal ions, using post‐source decay matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Kéki Sándor , Deák György , Zsuga Miklós 
Published: August 2002

AbstractA post‐source decay matrix‐assisted laser desorption/ionization mass spectrometric (PSD‐MALDI‐MS) study of rutin, a naturally occurring flavone glycoside cationized with different alkali metal ions, is reported. The fragmentations of rutin were performed by selecting the [R + Cat]+ peaks for PSD, where R represents a rutin molecule and Cat an alkali metal ion (Li+, Na+, K+). The PSD‐MALDI mass spectra showed, depending on Cat, different fragmentation patterns with respect to both the quality and quantity of the fragment ions formed. The intensity of fragmentation decreased in the order Li+ > Na+ > K+. The fragmentation mechanism and an explanation for the observed differences are suggested. Copyright © 2001 John Wiley & Sons, Ltd.
Resonant electron capture mass spectrometry of free fatty acids: examination of ion structures using deuterium‐labeled fatty acids and collisional activation
Authors: Voinov Valery G. , Van den Heuvel Hilde , Claeys Magda 
Published: August 2002

AbstractThe structures of [M–H]− ions generated from free fatty acids in resonant electron capture at energies of 1.2 and 7.2 eV were investigated using deuterium‐labeled isotopomers and collision‐induced dissociation. The [M–H]−· ions occur in both a carboxylate anion and a carbanion form. While the formation of the carboxylate anion at 1.2 eV involves the loss of a carboxylic hydrogen, that at 7.2 eV involves the loss of a hydrogen from different positions in the aliphatic chain followed by a rearrangement of a carboxylic hydrogen on to the radical site in the chain. The [M–H–H2O]− ion which is a minor ion in the resonant electron capture spectrum at 7.2 eV is shown to be a precursor for the charge‐remote fragment ions corresponding to formal losses of a hydrogen and elements of alkanes. The [M–H–H2O]− ion corresponding to the second major ion in the resonant electron capture spectrum at 7.2 eV is demonstrated to be consistent with a cyclopentanone anion structure. On the basis of new insights obtained in the present study and taking into account previous results, an updated proposal is presented for the mechanism of charge‐remote fragmentation which operates in resonant electron capture of free fatty acids at 7.2 eV. Copyright © 2002 John Wiley & Sons, Ltd.
9‐Nitrocamptothecin inhibits HIV‐1 replication in human peripheral blood lymphocytes: A potential alternative for HIV‐infection/AIDS therapy
Authors: Hung Chia‐Ling , Doniger Jay , Palini Alessio , Snyder Stuart W. , Radonovich Michael F. , Brady John N. , Pantazis Panayotis , Sadaie M. Reza 
Published: August 2002

AbstractThe ability of the anti‐cancer drug, 9‐Nitrocamptothecin (9NC), to inhibit replication of HIV‐1 in clinically relevant primary lymphocytic cells was studied. Primary peripheral blood lymphocytes (PBLs) from a non‐infected donor were freshly infected with HIV‐1 and treated with 9NC by using three different treatment schedules. Cells were monitored for cytotoxicity by the XTT metabolic cell proliferation assay and a sensitive flow cytometric assay that was capable of measuring cell cycle changes and apoptosis. 9NC inhibited replication of HIV‐1 in PBLs by greater than 95% in a dose‐dependent manner as measured by the level of extracellular HIV‐1 p24 release. Similar results were observed, whether 9NC was applied in a single, double, or triple dose regimen. Minimal cytotoxicity was observed for both non‐infected and infected PBLs, as determined by the XTT assay. Moreover, 9NC induced apoptosis within 24 hours of drug treatment in freshly infected, but not non‐infected, PBLs. The data showed that 9NC reduced replication of HIV‐1 in primary human lymphocytes; thus, it indicates the potential clinical utility of this drug as an alternative or adjunct therapy for HIV‐infection/AIDS. J. Med. Virol. 64:238–244, 2001. © 2001 Wiley‐Liss, Inc.
Genetic analysis of the capsid region of astroviruses
Authors: Wang Qiu‐Hong , Kakizawa Junko , Wen Le‐Ying , Shimizu Mitsugu , Nishio Osamu , Fang Zhao‐Yin , Ushijima Hiroshi 
Published: August 2002

AbstractEight serotypes of human astroviruses (HAstV‐1 to HAstV‐8) have been described. To date, the entire genomes of HAstV‐1 and HAstV‐2 as well as the ORF2 sequences of HAstV‐1–6 and 8 have been reported. In this study, the ORF2 sequences of seventeen strains of HAstVs originating from different countries were determined, as well as the sequence ORF2 of one porcine astrovirus (PAstV) strain. Afterwards, comparison of the capsid protein precursors encoded by ORF2 of 46 strains of HAstVs, PAstV, and feline astrovirus (FAstV) was carried out. A phylogenetic tree showed eight genogroups of HAstVs that corresponded exactly to the serotypes. HAstV‐3 and 7 were the most closely related, whereas HAstVs, FAstV, and PAstV segregated from each other. Compared to a PAstV, a FAstV is closer to HAstVs. Furthermore, the capsid protein precursors were divided into four regions (after amino acid residues 424, 688, and 776, respectively) based on sequence identity. Region I was the most conserved, and FAstV was very close in identity to HAstVs. Two amino acid motifs in region I were predicted to contain the common antigenic epitopes. Region II was relatively variable. Deletions and insertions were characteristic of region III, and region IV was relatively conserved. To our knowledge, this is the first comparative sequence analysis of the capsid protein precursors of eight serotypes of HAstVs as well as two animal astroviruses (FAstV and PAstV). J. Med. Virol. 64:245–255, 2001. © 2001 Wiley‐Liss, Inc.
Analysis of HIV drug‐resistant quasispecies in plasma, peripheral blood mononuclear cells and viral isolates from treatment‐naive and HAART patients
Authors: Paolucci Stefania , Baldanti Fausto , Campanini Giulia , Zavattoni Maurizio , Cattaneo Ercole , Dossena Luca , Gerna Giuseppe 
Published: August 2002

AbstractThe pattern of HIV‐1 reverse transcriptase and protease mutations conferring resistance to antiretroviral drugs was studied in five treatment‐naive patients and five HIV‐infected patients receiving HAART [two reverse transcriptase inhibitors + one protease inhibitor] for ≥ 1 year. Direct sequencing was performed on plasma HIV RNA, HIV DNA from peripheral blood mononuclear cells (PBMCs), and RNA from viral isolates. In addition, reverse transcriptase and protease PCR products from PBMCs HIV DNA, plasma HIV RNA, and viral isolate RNA were cloned in a plasmid to study the quasispecies distribution of drug‐resistance associated mutations. Direct sequencing of HIV DNA from PBMCs and HIV RNA from plasma and viral isolates did not show the presence of drug resistance associated mutations in both reverse transcriptase and protease of HIV from all five treatment‐naive patients. On the contrary, mutation analysis obtained by cloning plasma HIV RNA and PBMCs DNA showed the presence of drug‐resistance related mutations at a low frequency in both HIV enzymes of four out of five treatment‐naive patients. On the other hand, direct sequencing of plasma HIV RNA showed the presence of several reverse transcriptase and protease mutations in all five treated patients. Mutation analysis performed by cloning PBMCs HIV DNA, and HIV RNA from plasma and viral isolates, revealed additional reverse transcriptase and protease changes compared to direct sequencing of the relevant biological samples. All the additional changes were observed in a minority of clones. In conclusion, the data suggest that less frequent drug‐resistant viral variants not detected by direct sequencing of PBMCs, plasma samples, or viral isolates are present in both treatment‐naive and treatment‐experienced HIV patients. These findings may have important implications in the understanding of the selection process of drug‐resistant variants under drug pressure. J. Med. Virol. 65:207–217, 2001. © 2001 Wiley‐Liss, Inc.
Correlation of hepatitis B virus load with loss of e antigen and emerging drug‐resistant variants during lamivudine therapy
Authors: Zöllner Bernhard , Schäfer Peter , Feucht Heinz‐Hubert , Schröter Matthias , Petersen Jörg , Laufs Rainer 
Published: August 2002

AbstractIt remains unclear whether sequential assessment of hepatitis B virus (HBV) load during lamivudine therapy can predict the loss of hepatitis B e antigen or emergence of drug‐resistant variants. Therefore, a longitudinal study was carried out in 28 consecutive patients with chronic hepatitis B who started lamivudine therapy for a median of 12 months (range, 6–31). HBV DNA copy numbers were determined at 3‐month intervals. From month 6 onward, HBV viral load below the detection limit of the PCR was predictive of the loss of envelope antigen (P = 0.043). Continuously detectable HBV DNA during the first 12 months of treatment indicated emergence of drug‐resistant variants (P = 0.034). These data suggest that the goal of lamivudine therapy should be complete suppression of serum HBV DNA. J. Med. Virol. 65:659–663, 2001. © 2001 Wiley‐Liss, Inc.
GB virus C and TT virus infections in Japanese patients with autoimmune hepatitis
Authors: Nishiguchi Shuhei , Enomoto Masaru , Shiomi Susumu , Obata Noriko , Tanaka Motoharu , Fukuda Katsuhiko , Tamori Akihiro , Habu Daiki , Takeda Tadashi , Tanaka Takashi , Yano Yoshihisa , Otani Shuzo 
Published: August 2002

AbstractThe association of the newly identified viruses, GB virus C (GBV‐C) and TT virus (TTV), with autoimmune hepatitis remains to be elucidated. Sera from 20 Japanese patients with autoimmune hepatitis and 50 volunteer blood donors were assayed for GBV‐C RNA, antibodies to the GBV‐C second envelope protein (E2), and TTV DNA. GBV‐C RNA was examined by reverse‐transcription polymerase chain reaction (PCR). Anti‐GBV‐C E2 (a marker of past infection) was tested by an enzyme‐linked immunosorbent assay. TTV DNA was amplified by PCR using two different sets of primers: one derived from the original N22 sequence (Set A) and the other from the untranslated region (Set B). None of the patients or controls had GBV‐C RNA. Anti‐GBV‐C E2 was found significantly more often in patients with autoimmune hepatitis (3/20) than in controls (1/50; P = 0.034). The prevalence of TTV DNA detected by primers Set A and that detected with either Set A or B were similar among patients with autoimmune hepatitis (4/20 and 16/20, respectively) and controls (9/50 and 40/50, respectively). Clinical characteristics did not differ in association with any of these viral markers. Of the 13 TTV isolates amplified with Set A, seven were classified as genotype 1a, four as genotype 1b, and 2 as genotype 3; no particular strain was associated with autoimmune hepatitis. These findings provide no compelling evidence that GBV‐C or TTV has a pathogenic role in autoimmune hepatitis. J. Med. Virol. 66:258–262, 2002. © 2002 Wiley‐Liss, Inc.
Indirect modelling of the scattering from two‐dimensional composite uniaxial bianisotropic cylinders of arbitrary cross‐sections
Authors: Yin Wen‐Yan , Li Le‐Wei , Leong Mook‐Seng , Yeo Tat‐Soon 
Published: August 2002

AbstractThe indirect modelling of electromagnetic scattering from two‐dimensional composite uniaxial bianisotropic cylinders of arbitrary cross‐section is successfully performed according to the principle of equivolumetric model. The mathematical treatment here is based on the generalized boundary‐value method combined with the technique of separate variables. The solution is obtained from a system of linear equations of infinite order which is then truncated during numerical computations. Then, numerical investigation is carried out to demonstrate hybrid effects of geometrical and constitutive parameters of guest and host cylinders on the co‐ and cross‐polarized echo widths in the far‐field zone. It is shown that under certain circumstances, the indirect modelling technique is very efficient to study the scattering characteristics of many practical complex planar structures, and has some advantages over the direct numerical method. Copyright © 2001 John Wiley & Sons, Ltd.