bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization by matrix‐assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry of the major photoproducts of temoporfin (m‐THPC) and bacteriochlorin (m‐THPBC)
Authors: Angotti Marc , Maunit Benoît , Muller Jean‐François , Bezdetnaya Lina , Guillemin François 
Published: August 2002

AbstractThe photobleaching of 5,10,15,20‐tetrakis(m‐hydroxyphenyl)chlorin (temoporfin, m‐THPC) and 5,10,15,20‐tetrakis(m‐hydroxyphenyl)bacteriochlorin (bacteriochlorin, m‐THPBC) was studied in ethanol–water (1 : 99, v/v) and in physiological medium (phosphate‐buffered saline, PBS) with or without fetal calf serum (FCS). m‐THPC solution was irradiated with the laser radiation of 650 nm, whereas m‐THPBC solution underwent two consecutive irradiations at 532 and 650 nm. The photoproducts were characterized by UV–visible absorption spectrophotometry and by matrix‐assisted laser desorption/ionization (MALDI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS). Independent of the solvent used, the phototransformation of either photosensitizer yielded the formation of 5,10,15,20‐tetrakis (m‐hydroxyphenyl)porphyrin (m‐THPP) through a major dehydrogenation process. Copyright © 2001 John Wiley & Sons, Ltd.
Identification and characterization by high‐performance liquid chromatography/electrospray ionization mass spectrometry of a new variant hemoglobin, Mataro [β134(H12) Val > Ala]
Authors: Motos Gallardo A. , Hernández J. A. , Hernández J. M. , Rovira J. M. , Fluvià L. , Bosch A. , Pastor M. C. 
Published: August 2002

AbstractThis work illustrates the practical use of combined microbore reversed‐phase high‐performance liquid chromatography (RP‐HPLC) with electrospray ionization mass spectrometry (ESI‐MS) in protein identification. The approach consisted of the detection of the abnormal β‐globin chain by ESI‐MS analysis of mixtures of intact globins, which simultaneously provided their molecular masses. Separation of the polypeptide globin chains was carried out using microbore C4 RP‐HPLC on‐line with ESI‐MS. Direct peptide‐mapping ESI‐MS without previous chromatographic separation was performed in order to identify tryptic peptides from whole blood. For the sequence confirmation of the abnormal peptide containing the mutation point, C18 RP‐HPLC tryptic separation of the globin mixture on‐line with collision‐induced dissociation (CID) fragmentation was done. The y series ions allowed the identification of the hemoglobin (Hb) variant as [β134(H12) Val > Ala]. This new Hb was named Hb Mataró, after the city where it was detected. Copyright © 2001 John Wiley & Sons, Ltd.
Identification of glucuronide conjugates of ketobemidone and its phase I metabolites in human urine utilizing accurate mass and tandem time‐of‐flight mass spectrometry
Authors: Sundström Ingela , Hedeland Mikael , Bondesson Ulf , Andrén Per E. 
Published: August 2002

AbstractThe glucuronide conjugates of ketobemidone, norketobemidone and hydroxymethoxyketobemidone were identified in human urine post‐intravenous administration of Ketogan Novum. The human urine was extracted on a mixed‐mode solid‐phase micro‐column before analysis with liquid chromatography/electrospray ionization time‐of‐flight mass spectrometry (LC/ESI‐TOF‐MS) and tandem MS (MS/MS). Accurate mass and collision‐induced dissociation product ion spectra were used for identification of the glucuronide conjugates. Two different TOF mass spectrometers were used and the accurate mass measurements were performed on three separate days with each instrument. The accuracy of the mass measurements was better than 2.1 ppm for two out of three conjugates and the inter‐day relative standard deviation was within ±0.00049%. The MS/MS fragmentation patterns of the conjugates were in accordance with those of the synthetic aglycones and included peaks originating from the [M + H]+ ion of the respective aglycone. Copyright © 2002 John Wiley & Sons, Ltd.
Monitoring of in vitro deamidation of gliadin peptic fragment by mass spectrometry may reflect one of the molecular mechanisms taking place in celiac disease development
Authors: Novák Petr , Man Petr , Tučková Ludmila , Tlaskalová‐Hogenová Helena , Bezouška Karel , Havlíček Vladimír 
Published: August 2002

AbstractCeliac disease, a chronic disorder of the small intestine, is caused by dietary gluten and is characterized by villous atrophy and local inflammation associated with infiltration of B and T lymphocytes and/or macrophages into the intestinal wall. In genetically predisposed individuals, the infiltrating cells are activated by gluten, gliadin and their proteolytic fragments and produce chemokines, cytokines and reactive radicals. The sequence of one of the macrophage‐stimulatory gliadin peptic fragment was determined by mass spectrometry (MS) as VSFQQPQQQYPSSQ. The role of tissue transglutaminase (tTG) in innate immunity stimulation was studied by mass spectrometric monitoring of sequence changes in this active peptide. Two sites of glutamine deamidation in this peptide were localized by high‐resolution scanning in MS/MS mode in an ion trap. A single deamidation in the parent peptide led to the complete loss of its stimulatory effect on macrophages. Copyright © 2002 John Wiley & Sons, Ltd.
Protein identification with Teflon as matrix‐assisted laser desorption/ionization sample support
Authors: Yuan Xianglin , Desiderio Dominic M. 
Published: August 2002

AbstractProtein identification is a critical step in proteomics, and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) plays an important role in that identification. Polytetrafluoroethylene (Teflon) was tested as a new MALDI sample support to improve protein identification. The tryptic peptides obtained from a model protein were bound to the surface of a modified MALDI sample holder via the hydrophobic interactions that occur between the Teflon surface and the peptide ion‐pairs, and the affinity of α‐cyano‐4‐hydroxycinnamic acid for the peptides. During that surface‐binding step, the peptide mixture was also desalted and concentrated. A greater number of matched peptides and a larger sequence coverage were obtained for the proteins when Teflon was used as the sample support compared with conventional sample preparation methods and a stainless‐steel surface. In addition, the characterization of a small amount of protein was improved with Teflon. Nine silver‐stained protein spots obtained from 2‐D gel of a human cerebrospinal fluid (CSF) proteome were identified by this method. Among the nine protein spots, peptide 6:c3c fragment and procollagen c‐proteinase enhancer were not annotated in any published 2‐D map of human CSF. A Teflon MALDI sample support is a low‐cost, simple, and effective method that can be used to improve the quality of the MALDI mass spectrum of a complex tryptic peptide mixture, and to achieve a higher level of reliability and success in protein identification. Copyright © 2002 John Wiley & Sons, Ltd.
Lack of susceptibility of Chacma baboons (Papio ursinus orientalis) to hepatitis C virus infection
Authors: Sithebe N.P. , Kew M.C. , Mphahlele M.J. , Paterson A.C. , Lecatsas G. , Kramvis A. , de Klerk W. 
Published: August 2002

AbstractThe main reason to ascertain whether baboons are susceptible to infection with hepatitis C virus (HCV) is the need to replace chimpanzees, which are endangered, as an animal model for undertaking research into the biology and host–virus interactions of HCV, and for developing a vaccine against this virus. A second reason is that baboons are a possible source of xenografts for human liver transplantation. We inoculated serum containing HCV into four Chacma baboons and monitored them for 52 weeks for evidence of infection. Serum was tested for antibody to HCV, HCV RNA, and aminotransferase concentrations at 2‐week intervals for 26 weeks and thereafter at 4‐week intervals. Liver tissue was examined at 28 and 52 weeks for histopathological changes and viral RNA, and at 52 weeks for viral particles using electron microscopy. Reverse transcription‐polymerase chain reaction assay was used to detect HCV RNA, and the results were confirmed by Southern hybridization. Serum aminotransferase concentrations remained within the normal range and liver histology was normal during the follow‐up period. Passive transmission of anti‐HCV to the baboons was observed during the first 4 weeks. HCV RNA was not detectable in any serum or liver sample and electron microscopy failed to reveal viral particles in liver tissue. In conclusion, we did not find Chacma baboons to be susceptible to infection with HCV, although we cannot deny that in an immunosuppressed liver transplant recipient, infection of a baboon xenograft might occur. Another animal model for HCV infection must be sought. J. Med. Virol. 66:468–471, 2002. © 2002 Wiley‐Liss, Inc.
Reduced postnatal cerebral glucose metabolism measured by PET after asphyxia in near term fetal lambs
Authors: Thorngren‐Jerneck Kristina , Ley David , Hellström‐Westas Lena , Hernandez‐Andrade Edgar , Lingman Göran , Ohlsson Tomas , Oskarsson Gylfi , Pesonen Erkki , Sandell Anders , Strand Sven‐Erik , Werner Olof , Maršal Karel 
Published: August 2002

AbstractThe effects of fetal asphyxia on cerebral function and development, involve the transition from fetal to neonatal life. Changes in cerebral glucose metabolism may be an early postnatal indicator of fetal asphyxia. The objective is to develop an experimental lamb model involving the transition from fetal to neonatal life and to examine the effect of fetal asphyxia with cerebral hypoxic ischemia on early postnatal cerebral glucose metabolism. Fetal asphyxia was induced by total umbilical cord occlusion in eight near‐term fetal lambs (134–138 days) with the ewe under isoflurane‐opiate anesthesia. The mean occlusion time until cardiac arrest was 14.5 (4.2) min (SD). Lambs were immediately delivered and standardized resuscitation was instituted after 2 min asystole. At 4 hr postnatal age, [18‐F]Fluoro‐2‐deoxy‐glucose (18‐FDG) was injected intravenously in eight asphyxiated lambs and in eight controls. Cerebral glucose metabolism was examined by positron emission tomography (PET). As a result the mean arterial blood pressure, acid‐base values, blood glucose and serum lactate at 4 hr postnatal age did not differ significantly between lambs subjected to umbilical cord occlusion and controls. EEG was abnormal in all lambs subjected to cord occlusion and normal in the controls at 4 hr postnatal age. Global cerebral metabolic rate (CMRgl) as determined by PET was significantly lower in lambs subjected to cord occlusion mean/median (SD) 22.2/19.6 (8.4) μmol/min/100 g) than in controls mean/median (SD) 37.8/35.9 (6.1); P < 0.01). Global CMRgl is significantly reduced in newborn lambs 4 hr after fetal asphyxia induced by umbilical cord occlusion. A reduction in CMRgl is an early indicator of global hypoxic cerebral ischemia. © 2001 Wiley‐Liss, Inc.
Deletion of the C‐terminal domain of the NR2B subunit alters channel properties and synaptic targeting of N‐methyl‐D‐aspartate receptors in nascent neocortical synapses
Authors: Mohrmann Ralf , Köhr Georg , Hatt Hanns , Sprengel Rolf , Gottmann Kurt 
Published: August 2002

AbstractChannel properties and synaptic targeting of N‐methyl‐D‐aspartate (NMDA) receptors determine their importance in synaptic transmission, long‐term synaptic plasticity, and developmental reorganization of synaptic circuits. To investigate the involvement of the C‐terminal domain of the NR2B subunit in regulating channel properties and synaptic localization, we analyzed gene‐targeted mice expressing C‐terminally truncated NR2B subunits (NR2BΔC/ΔC mice; Sprengel et al. [1998] Cell 92:279–89). Because homozygous NR2BΔC/ΔC mice die perinatally, we studied embryonic neocortical neurons differentiating in culture. At early stages in vitro, neurons predominantly expressed NR1/NR2B receptors, as shown by the NR2B subunit‐specific antagonist ifenprodil. At these nascent synapses, NMDA excitatory postsynaptic currents (EPSCs) in neurons from NR2BΔC/ΔC mice showed a strong‐amplitude reduction to 20% of control, but AMPA EPSCs were unaltered. Analysis of the MK‐801 block of NMDA receptor‐mediated whole‐cell currents revealed a decreased peak open probability of NMDA receptor channels (to about 60%) in neurons from NR2BΔC/ΔC mice, although their single channel conductance was unchanged. To study effects on synaptic targeting, we determined the fraction of synaptically localized NMDA receptors relative to the whole‐cell NMDA receptor population. In neurons from NR2BΔC/ΔC mice, the synaptic NMDA receptor fraction was drastically reduced, suggesting that the C‐terminal domain of the NR2B subunit plays a major role in synaptic targeting of NMDA receptors at nascent synapses. With increasing time in culture, the reduction in NMDA EPSCs in neurons from NR2BΔC/ΔC mice diminished. This is explained by the expression of additional NMDA receptor subtypes containing NR2A subunits at more mature synapses. © 2002 Wiley‐Liss, Inc.
Proteins of peripheral myelin are associated with glycosphingolipid/cholesterol‐enriched membranes
Authors: Hasse B. , Bosse F. , Müller H.W. 
Published: August 2002

AbstractA characteristic feature of the vertebrate nervous system is the ensheathment of axons by myelin, a multilamellar membrane specialization produced by polarized glial cells. Although the main protein and lipid components of the myelin sheath are well characterized, relatively little is known about the mechanisms of their intracellular distribution to the respective sites of assembly within the myelin sheath. To analyze whether peripheral myelin protein trafficking is mediated by glycosphingolipid/cholesterol‐enriched membranes (GEMs), we studied the association of established myelin proteins, peripheral myelin protein 22 (PMP22), protein zero (P0), plasmolipin, and myelin basic protein (MBP), with these membrane microdomains. To examine the association of the selected peripheral myelin proteins with detergent‐insoluble GEMs, purified myelin from sciatic nerve of adult rat was extracted with Triton X‐100 at 4°C and 37°C and, in additional experiments, was pretreated with the cholesterol chelator methyl‐β‐cyclodextrin. The material was then centrifuged to equilibrium in sucrose gradients, and fractions were analyzed by Western blotting. Here we demonstrate for the first time that PMP22, P0, and plasmolipin prepared from purified peripheral myelin are associated with GEMs. To characterize whether the association of these proteins is a specialized feature of myelinating Schwann cells, we studied the distribution of PMP22, P0, and plasmolipin in transiently transfected HeLa cells. These experiments confirm the specific association of these proteins with GEMs in both neural and nonneural cell types. © 2002 Wiley‐Liss, Inc.
Inhibitory effect of neuropeptide Y on morphine withdrawal is accompanied by reduced c‐fos expression in specific brain regions
Authors: Clausen T.R. , Møller M. , Woldbye D.P.D. 
Published: August 2002

AbstractNeuropeptide Y (NPY) was previously shown in our laboratory to attenuate behavioral signs of morphine withdrawal. To further characterize the anti‐withdrawal effect of NPY, the present study attempted to identify specific brain regions where NPY inhibits neuronal activity during withdrawal. Morphine dependence was induced in male Wistar rats by two daily subcutaneous injections of morphine at increasing doses, and the withdrawal syndrome was precipitated acutely by intraperitoneal administration of naloxone. Rats were pre‐treated with an intracerebroventricular (icv) injection of NPY (12 nmol) or vehicle 30 min before the naloxone challenge. Withdrawal behavior was quantified using a point scoring technique based on motor‐ and non‐motor‐related signs. Brain areas involved in the attenuation of morphine withdrawal were delineated by radioactive in situ hybridization for the immediate early gene c‐fos, which is a marker for neuronal activity. The present study confirmed the inhibitory effect of NPY on withdrawal behavior. Inhibition of behavioral signs of naloxone‐precipitated morphine withdrawal was accompanied by significantly reduced c‐fos expression in the locus coeruleus, lateral septal nucleus, ventral part of the periaqueductal grey, cingulate and frontal cortices, and septohippocampal nucleus. Our data suggest that neo‐ and allo‐cortical areas as well as specific brainstem nuclei are involved in the anti‐withdrawal effects of NPY. J. Neurosci. Res. 64:410–417, 2001. © 2001 Wiley‐Liss, Inc.
NMDA receptor function in mouse models of Huntington disease
Authors: Cepeda Carlos , Ariano Marjorie A. , Calvert Christopher R. , Flores‐Hernández Jorge , Chandler Scott H. , Leavitt Blair R. , Hayden Michael R. , Levine Michael S. 
Published: August 2002

AbstractHuntington disease (HD) is an autosomal dominant disorder in which degeneration of medium‐sized spiny striatal neurons occurs. The HD gene and the protein it encodes, huntingtin, have been identified but their functions remain unknown. Transgenic mouse models for HD have been developed and we examined responses of medium‐sized striatal neurons recorded in vitro to application of N‐methyl‐D‐aspartate (NMDA) in two of these. The first model (R6/2) expresses exon 1 of the human HD gene with approximately 150 CAG repeats. In the R6/2 an enhancement of currents induced by selective activation of NMDA receptors as well as an enhancement of intracellular Ca2+ flux occurred in both presymptomatic and symptomatic mice. These alterations appeared specific for the NMDA receptor because α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazole propionic acid (AMPA) receptor‐mediated currents were reduced in symptomatic R6/2s. In R6/2 animals there were parallel increases in NMDA‐R1 and decreases in NMDA‐R2A/B subunit proteins as established by immunohistochemistry. The second model (YAC72) contains human genomic DNA spanning the full‐length gene and all its regulatory elements with 72 CAG repeats. The phenotypical expression of the disorder develops more gradually than in the R6/2. In YAC72 mice we found similar but less marked increases in responses of medium‐sized striatal neurons to NMDA. These findings indicate that alterations in NMDA receptor function may predispose striatal neurons to excitotoxic damage, leading to subsequent neuronal degeneration and underscore the functional importance of NMDA receptors in HD. J. Neurosci. Res. 66:525–539, 2001. © 2001 Wiley‐Liss, Inc.
The Pacific–South American modes and their downstream effects
Authors: Mo Kingtse C. , Paegle Julia N. 
Published: August 2002

AbstractThere are two pervasive modes of atmospheric variability in the Southern Hemisphere (SH) that influence circulation and rainfall anomalies over South America. They appear as leading empirical orthogonal functions (EOFs) of 500‐hPa height or 200‐hPa streamfunction anomalies and are found from intraseasonal to decadal time scales. Both patterns exhibit wave 3 hemispheric patterns in mid to high latitudes, and a well‐defined wave train with large amplitude in the Pacific–South American (PSA) sector. Therefore, they are referred to as the PSA modes (PSA1 and PSA2).PSA1 is related to sea surface temperature anomalies (SSTAs) over the central and eastern Pacific at decadal scales, and it is the response to El Niño–Southern Oscillation (ENSO) in the interannual band. The associated rainfall summer pattern shows rainfall deficits over northeastern Brazil and enhanced rainfall over southeastern South America similar to rainfall anomalies during ENSO. PSA2 is associated with the quasi‐biennial component of ENSO, with a period of 22–28 months and the strongest connections occur during the austral spring. The associated rainfall pattern shows a dipole pattern with anomalies out of phase between the South Atlantic Convergence Zone (SACZ) extending from central South America into the Atlantic and the subtropical plains centred at 35°S.These two modes are also apparent in tropical intraseasonal oscillations for both summer and winter. Eastward propagation of enhanced convection from the Indian Ocean through the western Pacific to the central Pacific is accompanied by a wave train that appears to originate in the convective regions. The positive PSA1 pattern is associated with enhanced convection over the Pacific from 150°E to the date line. The convection pattern associated with PSA2 is in quadrature with that of PSA1. Both PSA modes are influenced by the Madden Julian Oscillation and influence rainfall over South America. Copyright © 2001 Royal Meteorological Society
Interannual variability of winter precipitation in northern Iberian Peninsula
Authors: Sáenz Jon , Zubillaga Juan , Rodríguez‐Puebla Concepción 
Published: August 2002

AbstractObservational series of winter precipitation in the eastern part of the Cantabrian coast in the northern Iberian Peninsula are studied. This rather small area shows a clearly different interannual variability to the rest of the Peninsula. Series of winter precipitation for the whole area are defined using principal component (PC) analysis and they reflect the variability that can be attributed to changes in atmospheric circulation around the area. This variability is physically explained on the basis of the structure of baroclinic activity and vertically integrated moisture transports over the area derived from the NCEP/NCAR Reanalysis project. According to them, the leading PC of winter precipitation represents the overall precipitation over the area. Wet phases of this PC are associated to an increase of baroclinic activity leaving the eastern part of the Atlantic storm track and entering the Mediterranean basin. Conversely, dry phases show a strong reduction of baroclinic activity over the region. The second PC is linked to meridional water vapour transports over the area, which are affected by the topography of the region. Copyright © 2001 Royal Meteorological Society
A 40‐year climatological study of relative vorticity distribution over the Mediterranean
Authors: Flocas H.A. , Maheras P. , Karacostas T.S. , Patrikas I. , Anagnostopoulou C. 
Published: August 2002

AbstractA climatological study of the spatial and temporal distribution of mean relative geostrophic vorticity over the Mediterranean region is examined for a period of 40 years (1958–1997). Two major cyclonic vorticity maxima are found in the Mediterranean at low levels, one covers the Gulf of Genoa and south Italy and the second is located over the southeastern Aegean Sea with different diurnal and seasonal characteristics, controlling cyclone formation. At upper levels, a large scale cyclonic vorticity zone covers the whole Mediterranean region with notably increased values at 300 hPa, being associated with jet stream dynamics, especially in the eastern Mediterranean. The seasonal changes of the horizontal vorticity distribution substantially reduce with height while the diurnal changes become unimportant at upper levels. Furthermore, the investigation of the vertical vorticity structure separately for the main cyclonic centres in the Mediterranean implies the different mechanisms that are responsible for cyclone formation in the western and eastern basin. Copyright © 2001 Royal Meteorological Society