bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of arterial input function using fuzzy clustering for quantification of cerebral blood flow with dynamic susceptibility contrast‐enhanced MR imaging
Authors: Murase Kenya , Kikuchi Keiichi , Miki Hitoshi , Shimizu Teruhiko , Ikezoe Junpei 
Published: August 2002

AbstractAn accurate determination of the arterial input function (AIF) is necessary for quantification of cerebral blood flow (CBF) using dynamic susceptibility contrast‐enhanced magnetic resonance imaging. In this study, we developed a method for obtaining the AIF automatically using fuzzy c‐means (FCM) clustering. The validity of this approach was investigated with computer simulations. We found that this method can automatically extract the AIF, even under very noisy conditions, e.g., when the signal‐to‐noise ratio is 2. The simulation results also indicated that when using a manual drawing of a region of interest (ROI) (manual ROI method), the contamination of surrounding pixels (background) into ROI caused considerable overestimation of CBF. We applied this method to six subjects and compared it with the manual ROI method. The CBF values, calculated using the AIF obtained using the manual ROI method [CBF(manual)], were significantly higher than those obtained with FCM clustering [CBF(fuzzy)]. This may have been due to the contamination of non‐arterial pixels into the manually drawn ROI, as suggested by simulation results. The ratio of CBF(manual) to CBF(fuzzy) ranged from 0.99–1.83 [1.31 ± 0.26 (mean ± SD)]. In conclusion, our FCM clustering method appears promising for determination of AIF because it allows automatic, rapid and accurate extraction of arterial pixels. J. Magn. Reson. Imaging 2001;13:797–806. © 2001 Wiley‐Liss, Inc.
BOLD MRI of human tumor oxygenation during carbogen breathing
Authors: Taylor N. Jane , Baddeley Hiram , Goodchild Kate A. , Powell Melanie E. B. , Thoumine Michelle , Culver Linda A. , Stirling J. James , Saunders Michele I. , Hoskin Peter J. , Phillips Heather , Padhani Anwar R. , Griffiths John R. 
Published: August 2002

AbstractAn MRI method is described for demonstrating improved oxygenation of human tumors and normal tissues during carbogen inhalation (95% O2, 5% CO2). T‐weighted gradient‐echo imaging was performed before, during, and after carbogen breathing in 47 tumor patients and 13 male volunteers. Analysis of artifacts and signal intensity was performed. Thirty‐six successful tumor examinations were obtained. Twenty showed significant whole‐tumor signal increases (mean 21.0%, range 6.5–82.4%), and one decreased (−26.5 ± 8.0%). Patterns of signal change were heterogeneous in responding tumors. Five of 13 normal prostate glands (four volunteers and nine patients with nonprostatic tumors) showed significant enhancement (mean 11.4%, range 8.4–14.0%). An increase in brain signal was seen in 11 of 13 assessable patients (mean 8.0 ± 3.7%, range 5.0–11.7%). T‐weighted tumor MRI during carbogen breathing is possible in humans. High failure rates occurred due to respiratory distress. Significant enhancement was seen in 56%, suggesting improved tissue oxygenation and blood flow, which could identify these patients as more likely to benefit from carbogen radiosensitization. J. Magn. Reson. Imaging 2001;14:156–163. © 2001 Wiley‐Liss, Inc.
An introduction to quadrupole–time‐of‐flight mass spectrometry
Authors: Chernushevich Igor V. , Loboda Alexander V. , Thomson Bruce A. 
Published: August 2002

AbstractA brief introduction is presented to the basic principles and application of a quadrupole–time‐of‐flight (TOF) tandem mass spectrometer. The main features of reflecting TOF instruments with orthogonal injection of ions are discussed. Their operation and performance are compared with those of triple quadrupoles with electrospray ionization and matrix‐assisted laser desorption/ionization (MALDI) TOF mass spectrometers. Examples and recommendations are provided for all major operational modes: mass spectrometry (MS) and tandem MS (MS/MS), precursor ion scans and studies of non‐covalent complexes. Basic algorithms for liquid chromatography/MS/MS automation are discussed and illustrated by two applications. Copyright © 2001 John Wiley & Sons, Ltd.
In‐source fragmentation of peptide aldehydes and acetals: influence of peptide length and charge state
Authors: Buré Corinne , Gobert Wilfried , Lelièvre Dominique , Delmas Agnès 
Published: August 2002

AbstractThe use of in‐source collision‐induced dissociation (CID) was evaluated to generate structural information on peptide aldehydes, which represent an important class of compounds as inhibitors for serine and cysteine proteases and as key intermediates for protein engineering. By studying five peptide aldehydes of different lengths, and their peptide acetal counterparts, mass to charge (m/z) dependency of in‐source fragmentation was established for peptides that differ only by their C‐terminal functionalization. In‐source fragmentation of peptide aldehydes and acetals leads to the same final ion, probably via a similar mechanism. Moreover, the gas‐phase information obtained here reflects the equilibrium occurring in solution between the peptide aldehyde and its hydrated form, which was retained during the ionization process. The equilibrium constant was determined to be close to unity. Disturbance of this equilibrium should enable the stability of covalent hydration of a given series of aldehydes to be compared. Copyright © 2001 John Wiley & Sons, Ltd.
Conformational antigenic determinants generated by interactions between a bacterially expressed recombinant peptide of the hepatitis E virus structural protein
Authors: Zhang Ji‐Zhong , Ng Mun H. , Xia N. S. , Lau S. H. , Che X. Y. , Chau T. N. , Lai S. T. , Im Stanley W. K. 
Published: August 2002

AbstractA 23 kDa peptide locating to amino acid residues 394 to 604 of the major Hepatitis E Virus (HEV) structural protein was expressed in E. coli. This peptide was found to interact naturally with one another to form homodimers and it was recognized strongly and commonly in its dimeric form by HEV reactive human sera. The antigenic activity associated with the dimeric form was abrogated when the dimer was dissociated into monomer and the activity was reconstituted after the monomer was re‐associated into dimer again. The dimeric form of the peptide elicited a vigorous antibody response in experimental animals and the resulting antisera were found to cross‐react against HEV, effecting an efficient immune capture of the virus. These results attributed the antigenic activity associated with the dimeric form of the peptide to conformational antigenic determinants generated as a result of interaction between the peptide molecules. It is suggested that some of these antigenic determinants may be expressed by the HEV capsid and raised the possibility of this bacterially expressed peptide as an HEV vaccine candidate. J. Med. Virol. 64:125–132, 2001. © 2001 Wiley‐Liss, Inc.
Identification of the 5′ terminal sequence of the SAR‐55 and MEX‐14 strains of hepatitis E virus and confirmation that the genome is capped
Authors: Zhang Mingdong , Purcell Robert H. , Emerson Suzanne U. 
Published: August 2002

AbstractHepatitis E virus (HEV) is a nonenveloped virus with a genome of single‐stranded, positive‐sense RNA. The 5′ terminal sequence of two HEV strains (SAR‐55 and MEX‐14) was determined by a 5′ RNA ligase‐mediated rapid amplification of cDNA ends (RACE) method designed to select capped RNAs. The 5′ noncoding region of the SAR‐55 and MEX‐14 strains were amplified, confirming that the genomic RNA of HEV is capped. The 5′ noncoding region of the SAR‐55 strain had 25 nucleotides, which is two less than reported for the Burmese strain, and that of the MEX‐14 strain had 24 nucleotides, which is 21 more than reported previously [Huang et al., 1992]. J. Med. Virol. 65:293–295, 2001. © 2001 Wiley‐Liss, Inc.
Amino acid and phenotypic changes in dengue 2 virus associated with escape from neutralisation by IgM antibody
Authors: Lok Shee Mei , Ng Mah Lee , Aaskov John 
Published: August 2002

AbstractTwo dengue 2‐specific IgM monoclonal antibodies (MAb) recognised spatially unrelated epitopes on the envelope (E) protein of dengue 2 virus, which were also recognised by serum from 20 and 50%, respectively, of patients with a primary dengue 2 infection. Dengue 2 virus populations escaping neutralisation by MAb 6B2 (representing the majority population of dengue 2‐specific IgM MAbs ) had a deduced amino acid change (G‐S) in the pre‐Membrane (prM) protein at position 15 and a second in the E protein at E311 (E‐G). The change in the E protein was adjacent to the only other epitopes on dengue 2 virus (E307, E383‐385) involved in neutralisation that have been identified but that were recognised by IgG antibodies. Dengue 2 virus escaping neutralisation by IgM MAb 10F2, representing the minority population of dengue 2‐specific IgM MAbs, had the same deduced amino acid change (G‐S) at prM15 as the 6B2 neutralisation escape mutant dengue 2 virus population and four deduced amino acid changes in the E protein (E69, T‐I, in the glycosylation motif; E71, E‐D; E112, S‐G; E124, I‐N), which may be close enough to each other to form a single epitope and a fifth at E402 (F‐L) in a region of the E protein of TBE virus essential for the low pH‐induced E protein dimer‐trimer transition. The 10F2 neutralisation escape mutant, but not the 6B2 one, had lost its ability to cause fusion from within Aedes albopictus mosquito cells and was inactivated more rapidly than the 6B2 neutralisation escape mutant and wild type viruses at 42°C. Dengue 2 viruses passaged in BHK cells in the absence of a selecting antibody, shared a common amino acid (S) at E53, which differed from both wild type and neutralisation escape mutant virus populations at this position (P) and may have been responsible for a significant reduction in the ability of these “passage control” virus populations to be neutralised by both 6B2 and 10F2 antibodies. J. Med. Virol. 65:315–323, 2001. © 2001 Wiley‐Liss, Inc.
HHV‐6 A‐ or B‐specific P41 antigens do not reveal virus variant‐specific IgG or IgM responses in human serum
Authors: Xu Yunhe , Linde Annika , Fredrikson Sten , Dahl Helena , Winberg Gösta 
Published: August 2002

AbstractThe etiology of multiple sclerosis (MS) remains unknown, but there are indications of a role of human herpesvirus 6 (HHV‐6), especially variant A, in the pathogenesis. Higher serum antibody reactivity against an HHV‐6 early protein, p41, has been found in MS cases than in controls. The antigen, however, was purified from infected cells with a monoclonal antibody also reactive with a protein (p38) likely to be of cellular origin. To avoid serological crossreactivity with the cellular protein, recombinant p41 proteins from HHV‐6A strain GS and HHV‐6B strain Z29 were expressed as glutathione‐S‐transferase fusion proteins (p41‐GST), and used as antigens in an enzyme‐linked immunosorbent assay (ELISA). p41 variant specific monoclonal antibodies reacted strongly with the respective recombinant proteins. Serum IgM and IgG reactivities with the recombinant p41 antigens were analysed in patients with manifest MS, patients with optic neuritis, patients with other neurological diseases, and in one group of healthy controls. All sera were HHV‐6 IgG seropositive by immunofluorescence. The serum IgM or IgG reactivities against the recombinant p41 antigens did not differ significantly between the groups, and the reactivities against the variant A and B antigens were identical. In many samples, the reactivity was very low. The results indicate that p41 is not an optimal target for HHV‐6 serology studies, and that the data obtained with the p41 antigen prepared from infected cells (possibly including also p38) should be interpreted with caution. J. Med. Virol. 66:394‐399, 2002. © 2002 Wiley‐Liss, Inc.
Incidence and case‐fatality rates resulting from the 1998 enterovirus 71 outbreak in Taiwan
Authors: Lu Chun‐Yi , Lee Chin‐Yun , Kao Chuan‐Liang , Shao Wen‐Yi , Lee Ping‐Ing , Twu Shiing‐Jer , Yeh Chin‐Chuan , Lin Shang‐Ching , Shih Wen‐Yi , Wu Shiow‐Ing , Huang Li‐Min 
Published: August 2002

AbstractIn 1998, an epidemic of hand‐foot‐and‐mouth disease and herpangina caused by enterovirus 71 occurred in Taiwan, leaving many fatalities and severely handicapped survivors in its wake. The reasons this rather common pathogen would cause such a large‐scale epidemic remain unknown. A seroepidemiological survey to elucidate the epidemiological characteristics of this outbreak, including its incidence and case‐fatality rates was undertaken. Microneutralization tests for antibodies against enterovirus 71 were used to screen four collections of serum samples: 1) 202 specimens taken from individuals ≥ 4 years old in 1994; 2) 245 specimens collected from individuals of all ages in 1997; 3) 1,258 specimens collected from individuals of all ages in 1999; and 4) sera samples from a birth cohort of 81 children who had yearly blood samples taken from 1988–98. After the maternal antibody had declined, the seropositive rates began to increase with age. Approximately half of all children aged 6 years or older were enterovirus 71 seropositive. Significantly higher seropositive rates were noted in 1999 than in 1997, in children aged 0.5–3 years. The incidence of enterovirus 71 infection during the epidemic was estimated to be 13–22%, with the higher rates in younger children. The case‐fatality rate was highest (96.96 per 100,000) in infants aged 6–11 months, and declined in older children. The results showed that enterovirus 71 is endemic in Taiwan. The apparent lack of large‐scale enterovirus 71 activity in the 3 years before 1998 might have been the prelude to the epidemic's appearance in 1998, and might suggest that enterovirus 71 infection will reappear every few years. The lack of a protective antibody in younger children may account for the high incidence and case‐fatality rate in this age group. J. Med. Virol. 67:217–223, 2002. © 2002 Wiley‐Liss, Inc.
Extended PML‐TLM node: an efficient approach for full‐wave analysis of open structures
Authors: Le Maguer S. , Ney M. M. 
Published: August 2002

AbstractThis paper deals with an extension and improvement of the PML‐TLM algorithm first proposed by Dubard and Pompei. The approach is first extended to advanced nodes (hybrid SCN and super‐SCN). Then its efficiency in the presence of evanescent waves is improved. As a result, stability is also improved. Finally, the algorithm is applied to the characterization of a new class of patch antennas and validated by the measurement. Copyright © 2001 John Wiley & Sons, Ltd.
Split‐step‐Gauss–Hermite algorithm for fast and accurate simulation of soliton propagation
Authors: Lazaridis P. , Debarge G. , Gallion P. 
Published: August 2002

AbstractA simple and efficient algorithm is proposed for the numerical solution of the non‐linear Schrödinger equation. Operator splitting is used, as with the split‐step‐Fourier method, in order to treat the linear part and the non‐linear part of the equation separately. However, in our method, the FFT solution of the linear part is replaced by a very accurate Gauss–Hermite orthogonal expansion. Gaussian quadrature nodes and weights are used in order to calculate the expansion coefficients. Our methods is found to be very accurate and faster than the split‐step‐Fourier method for the model problem of single soliton propagation. Copyright © 2001 John Wiley & Sons, Ltd.
Regulation of mRNA stability in the nervous system and beyond
Authors: Malter James S. 
Published: August 2002

AbstractThe ability to control gene expression is central to normal development and function. For a growing number of genes in the central nervous system and peripheral tissues, expression is determined by changes in the rate of mRNA decay. At a molecular level, regulated interactions between the mRNA target and sequence‐specific binding proteins either inhibit or accelerate decay, affording tight control over gene expression. This review discusses several examples of such posttranscriptional gene regulation. J. Neurosci. Res. 66:311–316, 2001. © 2001 Wiley‐Liss, Inc.
Monitoring arterio‐venous differences of glucose and lactate in the anesthetized rat with or without brain damage with ultrafiltration and biosensor technology
Authors: Leegsma‐Vogt Gea , Venema Kor , Postema Folkert , Korf Jakob 
Published: August 2002

AbstractContinuous monitoring of arterio‐venous glucose and lactate differences may serve as a diagnostic tool to assess normal brain function and brain pathology. We describe a method and some results obtained with arterio‐venous measurements of glucose and lactate in the blood of the halothane‐anesthetized rat and after brain injury. The method is based on low flow rate ultrafiltration for continuous collection of blood filtrate combined with flow injection analysis and biosensors for the detection of glucose and lactate. We measured the glucose and lactate concentration every minute in the jugular vein and the aorta at control conditions and during and after inflation of an embolectomy‐balloon for 2 min. Net cerebral lactate efflux and glucose uptake was seen under control conditions and at low blood lactate levels. During brain injury both lactate release and glucose uptake were reduced and there was a net lactate influx at high arterial lactate levels. These results indicate that the flux of lactate in and out of the brain is not only dependent on the lactate concentration in the brain, but on blood levels as well, possibly because of bi‐directional flux through the monocarboxylate transporter type 1. © 2001 Wiley‐Liss, Inc.
Regulation of human glutamate dehydrogenases: Implications for glutamate, ammonia and energy metabolism in brain
Authors: Plaitakis Andreas , Zaganas Ioannis 
Published: August 2002

AbstractGlutamate dehydrogenase (GDH) catalyzes the oxidative deamination of glutamate to α‐ketoglutarate using NAD or NADP as cofactors. In mammalian brain, GDH is located predominantly in astrocytes, where it is probably involved in the metabolism of transmitter glutamate. The exact mechanisms that regulate glutamate fluxes through this pathway, however, have not been fully understood. In the human, GDH exists in heat‐resistant and heat‐labile isoforms, encoded by the GLUD1 (housekeeping) and GLUD2 (nerve tissue‐specific) genes, respectively. These forms differ in their catalytic and allosteric properties. Kinetic studies showed that the Km value for glutamate for the nerve tissue GDH is within the range of glutamate levels in astrocytes (2.43 mM), whereas for the housekeeping enzyme, this value is significantly higher (7.64 mM; P < 0.01). The allosteric activators ADP (0.1–1.0 mM) and L‐leucine (1.0–10.0 mM) induce a concentration‐dependent enzyme stimulation that is proportionally greater for the nerve tissue‐specific GDH (up to 1,600%) than for the housekeeping enzyme (up to 150%). When used together at lower concentrations, ADP (10–50 mM) and L‐leucine (75–200 μM) act synergistically in stimulating GDH activity. GTP exerts a powerful inhibitory effect (IC50 = 0.20 mM) on the housekeeping GDH; in contrast, the nerve tissue isoenzyme is resistant to GTP inhibition. Thus, although the housekeeping GDH is regulated primarily by GTP, the nerve tissue GDH activity depends largely on available ADP or L‐leucine levels. Conditions associated with enhanced hydrolysis of ATP to ADP (e.g., intense glutamatergic transmission) are likely to activate nerve tissue‐specific GDH leading to an increased glutamate flux through this pathway. © 2001 Wiley‐Liss, Inc.
Differential regulation of myelin phagocytosis by macrophages/microglia, involvement of target myelin, Fc receptors and activation by intravenous immunoglobulins
Authors: Kuhlmann Tanja , Wendling Uwe , Nolte Christiane , Zipp Frauke , Maruschak Brigitte , Stadelmann Christine , Siebert Heike , Brück Wolfgang 
Published: August 2002

AbstractMacrophages/microglia are the key effector cells in myelin removal. Differences exist in the amount and time course of myelin uptake in the central (CNS) and peripheral nervous system (PNS), the basis of this difference, however, is not yet clarified. In the present experiments we studied the phagocytosis rate of CNS or PNS myelin by macrophages and microglia in vitro. Additionally, the effects of intravenous immunoglobulins (IVIg) on this process were investigated. In the PNS experiments, sciatic nerves were cocultured with peritoneal macrophages. Optic nerve fragments were used to characterize the myelin‐removing properties of microglia. Cocultures with peritoneal macrophages aimed at investigating the differences in phagocytosis between resident microglia and added macrophages. The myelin phagocytosis in sciatic nerve fragments was higher than in optic nerves, indicating differences in the myelin uptake rate between peripheral macrophages and microglia. IVIg increased the phagocytosis of PNS myelin by macrophages, but not by microglia in optic nerves. The addition of peritoneal macrophages to optic nerve fragments did not lead to an increase in the phagocytosis of CNS myelin either. The IVIg induced phagocytosis of PNS myelin by peripheral macrophages was associated with an increased expression of macrophage Fc receptors measured by FACS. Blocking of Fc receptors by anti‐Fc receptor antibody reduced the IVIg induced PNS myelin phagocytosis to basic levels, indicating that the induced but not the basic myelin uptake by macrophages is Fc receptor dependent. In contrast to peripheral macrophages, IVIg did not increase Fc receptor density on microglia. These data indicate that phagocytosis of PNS and CNS myelin by macrophages or microglia is differentially regulated. Local factors within the CNS or PNS may affect this process by modulating the surface receptor profile and activation state of the phagocytic cell or the structure of the myelin sheath. © 2002 Wiley‐Liss, Inc.
Analysis of gene expression in the rat hippocampus using real time PCR reveals high inter‐individual variation in mRNA expression levels
Authors: Alfonso Julieta , Pollevick Guido D. , Castensson Anja , Jazin Elena , Frasch Alberto C.C. 
Published: August 2002

AbstractIn mammals, gene transcription is a step subjected to tight regulation mechanisms. In fact, changes in mRNA levels in the central nervous system (CNS) can account for numerous phenotypic differences in brain function. We performed a high‐resolution analysis of mRNA expression levels for 37 genes selected from a normal rat hippocampus cDNA library. mRNA amounts were quantified using a Real Time PCR SYBR Green assay. We found that, in general, individuals from an inbred rat population (n = 20) have shown 2–3 times differences in the basal level of expression of the genes analyzed. Up to several fold differences among individuals were observed for certain genes. These inter‐individual differences were obtained after correction for the different amounts of mRNA in each sample. Power calculations were performed to determine the number of individuals required to detect reliable differences in expression levels between a control and an experimental group. These data indicated that, depending on the variability of the candidate gene selected, it was necessary to analyze from five to 135 individuals in each group to detect differences of 50% in the levels of mRNA expression between two groups investigated. The comparison of mRNA abundance from different genes revealed a wide range of expression levels for the 37 genes, showing a 26,000‐fold difference between the highest and lowest expressed gene. © 2002 Wiley‐Liss, Inc.