bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic coronary MR angiography and first‐pass perfusion with intracoronary administration of contrast agent
Authors: Tsekos Nikolaos V. , Woodard Pamela K. , Foster Glenn J. , Moustakidis Pavlos , Sharp Terry L. , Herrero Pilar , Gropler Robert J. 
Published: September 2002

AbstractPurposeTo evaluate whether dynamic imaging of the coronary arteries can be performed with intracoronary infusion of low‐dose gadolinium (Gd)‐based contrast agent and assess the effect of long duration and multiple infusions on the image signal‐to‐noise ratio (SNR) and contrast‐to‐noise ratio (CNR).Materials and MethodsDynamic coronary magnetic resonance (MR) imaging (130 msec/image) and contrast agent first pass myocardial perfusion studies were performed with intracoronary infusions of low‐dose Gd‐based MR contrast agent on dogs (N = 4) using a fast multislice gradient recalled echo (GRE) sequence.ResultsContrast‐enhanced coronary arteries were clearly imaged during infusion periods as long as 2.3 minutes. The SNR and CNR of the contrast‐enhanced coronary arteries remained essentially unchanged over multiple consecutive angiographic sessions. In addition, we demonstrated that first pass studies performed with intracoronary injection of MR contrast agent can be used as a means of assessing regional myocardial perfusion.ConclusionThese studies demonstrated that, using intracoronary infusion of Gd, coronary magnetic resonance angiography (MRA) can be performed with high temporal resolution, and multiple low‐dose slow infusions of Gd‐based MR contrast agent can be performed without compromise of the vessel SNR and CNR. J. Magn. Reson. Imaging 2002;16:311–319. © 2002 Wiley‐Liss, Inc.
Hybrid phased array for improved internal auditory canal imaging at 3.0‐T MR
Authors: Kocharian Armen , Lane John I. , Bernstein Matt A. , Lin Chen , Witte Robert J. , Huston John , Felmlee Joel P. 
Published: September 2002

AbstractPurposeTo develop and evaluate a hybrid phased array for internal auditory canal (IAC) imaging at 3.0 T.Materials and MethodsA hybrid phased array was designed and built as two circular surface receive‐only coils combined with a volume transmit‐receive birdcage head coil for simultaneous image acquisition. Phantom and volunteer images were obtained to assess the coil performance.ResultsThe phantom data show that significant signal‐to‐noise ratio (SNR) improvement was achieved in the region corresponding to the inner ear, i.e., by a factor of 2.5 compared to the standard head coil data. Volunteer IAC image quality was deemed superior as compared to images acquired at 3.0 T using a standard head coil.ConclusionThis hybrid array combined with three‐dimensional fast spin‐echo (FSE) acquisition resulted in improved high spatial resolution IAC imaging. J. Magn. Reson. Imaging 2002;16:300–304. © 2002 Wiley‐Liss, Inc.
Evaluation of tissue perfusion in a rat model of hind‐limb muscle ischemia using dynamic contrast‐enhanced magnetic resonance imaging
Authors: Luo Yanping , Mohning Kurt M. , Hradil Vincent P. , Wessale Jerry L. , Segreti Jason A. , Nuss Merrill E. , Wegner Craig D. , Burke Sandra E. , Cox Bryan F. 
Published: September 2002

AbstractPurposeTo evaluate the feasibility of using dynamic contrast‐enhanced magnetic resonance imaging (MRI) for assessment of muscle perfusion in a rat model of hind‐limb ischemia.Materials and MethodsThe acute alteration and chronic recovery in muscle perfusion and perfusion reserve after femoral artery ligation were quantified using the maximum Gd‐DTPA uptake rate obtained by a T1‐weighted gradient‐recalled echo sequence. Radionuclide‐labeled microsphere blood flow measurements were performed for comparison with the MR perfusion measurement on a separate set of animals.ResultsAfter femoral artery ligation, a significant reduction in resting muscle perfusion was only observed at 1 hour post‐ligation during the 28‐day follow‐up period. Muscle perfusion reserve was severely diminished following the ligation. Despite significant recovery over time, perfusion reserve to the ligated limb reached only 63% of the perfusion capacity in the unaffected limb by 42 days post ligation. A strong correlation (r = 0.86) between MR perfusion and microsphere blood flow measurements was observed for evaluation of relative changes in muscle perfusion.ConclusionDynamic contrast‐enhanced MRI with Gd‐DTPA is useful to assess time‐dependent changes in muscle perfusion and perfusion reserve in this hind‐limb ischemia model. J. Magn. Reson. Imaging 2002;16:277–283. © 2002 Wiley‐Liss, Inc.
Isomer separation of hyperbranched polyesteramides with gas‐phase H/D exchange and a novel MSn approach: DoDIP
Authors: Koster Sander , Duursma Marc C. , Guo Xinghua , van Benthem Rolf. A. T. M. , de Koster Chris G. , Boon Jaap J. , Heeren Ron M. A. 
Published: September 2002

AbstractTwo approaches are introduced that provide information about the isomeric composition of hyperbranched polyesteramides. The first approach is based on a novel tandem mass spectrometric (MSn) approach that allows the study of different types of isomeric structures by a separation based on their difference in appearance energy. The method is called DoDIP: dissociation of depleted ion populations. A first MS/MS step is used to fragment isomers with relatively low appearance energy. The isomers with higher appearance energy are fragmented in a second MS/MS step of higher energy. The second approach is based on gas‐phase H/D exchange experiments that result in a bimodal isotopic distribution for oligomers XnDn+1 of which one distribution corresponds to a type of isomeric structure that exhibits H/D exchange behaviour and the other to an isomeric structure that does not exhibit H/D exchange behaviour. X is a difunctional anhydride of phthalic acid (P), 1,2‐cyclohexanedicarboxylic acid (C), succinic acid (S) or glutaric acid (G). D in XnDn+1 is a trifunctional diisopropanolamine and n the degree of polymerization. The type of isomeric structure that does not exhibit H/D exchange behaviour has a non‐alternating monomer sequence that contains an amine bond with a relatively high proton affinity. The other isomeric structure that does exhibit H/D exchange behaviour has an alternating monomer sequence containing only amide and ester bonds with relatively low proton affinity. Oligomer structures were confirmed with additional MS2 experiments after H/D exchange. H/D exchange experiments on the fragments obtained after MS2 of the parent ion show that next to previously postulated mechanisms for the cleavage of the ester and amide bond another reaction pathway must be operational. A new mechanism is introduced to explain the H/D exchange behaviour of the fragments that requires a cleavage of the amide bonds only. Two types of fragments are formed by this mechanism. One type is protonated due to the cleavage of the amide bond whereas the other type has an oxazolonium ion structure due to the loss of an additional H2O. Copyright © 2002 John Wiley & Sons, Ltd.
Tracing glycoprotein structures: electrospray ionization tandem mass spectrometric analysis of sugar–peptide adducts
Authors: Jerić Ivanka , Versluis Cornelis , Horvat Štefica , Heck Albert J. R. 
Published: September 2002

AbstractOwing to the diversity of carbohydrate structures and their significance for the function of many biopolymers, structural analysis of various carbohydrate‐related compounds is of great importance. Electrospray ionization tandem mass spectrometry (ESI‐MS/MS) was used to establish the fragmentation behaviour of a range of sugar–peptide adducts as model compounds of widespread glycoprotein structures. The compounds used in this study were chosen to provide correlation of distinct fragment ions with specific structural differences, namely position and type of carbohydrate–peptide bond and structure of the sugar moiety. All compounds show N‐ and C‐terminal sequence ions along with losses of up to three water molecules. Fructose‐related Amadori compounds exhibit M + 78 modified N‐terminal peptide fragment ions. Fragmentation of glucose–peptide esters is characterized by the sugar ring fragmentation. Additionally, under the ESI‐MS conditions applied, the esters studied undergo intramolecular reaction giving cyclic sugar–peptide structures that can be traced by the presence of N‐terminal peptide M + 42 adducts. Detailed analysis of cyclic fructose‐related compound comprising structural features of both studied groups revealed a rich fragmentation pattern derived from amino acid residues and water molecules losses from [M − 2H2O + H]+ ion. Also, some interesting differences were found with respect to the nature of carbohydrate moieties. Copyright © 2002 John Wiley & Sons, Ltd.
Determination of clindamycin in animal plasma by high‐performance liquid chromatography combined with electrospray ionization mass spectrometry
Authors: Cherlet Marc , Croubels Siska , De Backer Patrick 
Published: September 2002

AbstractA method for the quantification of clindamycin in animal plasma using high‐performance liquid chromatography combined with electrospray ionization mass spectrometry (LC/ESI‐MS/MS) is presented. Lincomycin is used as the internal standard. The sample preparation includes a simple deproteinization step with trichloroacetic acid. Chromatographic separation is achieved on an RP‐18 Hypersil column using gradient elution with 0.01 M ammonium acetate and acetonitrile as mobile phase. Good linearity was observed in the range 0–10 µg ml−1. The limit of quantification of the method is 50 ng ml−1 and the limit of detection is 1.3 ng ml−1. The method was shown out to be of use for pharmacokinetic studies of clindamycin formulations in dogs. Copyright © 2002 John Wiley & Sons, Ltd.
Mass spectrometric identification of in vivo carbamylation of the amino terminus of Ectothiorhodospira mobilis high‐potential iron–sulfur protein, isozyme 1
Authors: Van Driessche G. , Vandenberghe I. , Jacquemotte F. , Devreese B. , Van Beeumen J. J. 
Published: September 2002

AbstractThe complete amino acid sequence of a novel high‐potential iron–sulfur protein (HiPIP) isozyme 1 from the moderately halophilic phototrophic bacterium Ectothiorhodospira mobilis was determined by a combined approach of chemical and mass spectrometric sequencing techniques. By mass analysis of the apo‐ and holo‐protein in the positive electrospray ionization mode using different electrospray solvents, the protein was found to be post‐translationally modified by a moiety of 43 Da. Further analysis showed the nature and location of this modification to be a carbamyl group at the N‐terminus of the HiPIP. This rare type of modification has previously been reported to occur in the water‐soluble human lens αB‐crystallin, class D β‐lactamases and some prokaryotic ureases, albeit at an internal lysine residue. In this paper, we discuss the mass spectrometric features of a carbamylated residue at the N‐terminus of a peptide or a lysine side‐chain during sequence analysis by collision‐induced dissociation tandem mass spectrometry. Our data provide evidence for the first case of a prokaryotic carbamylated electron transport protein occurring in vivo. Copyright © 2002 John Wiley & Sons, Ltd.
Operation of an academic open access mass spectrometry facility with particular reference to the analysis of synthetic compounds
Authors: Greaves John 
Published: September 2002

AbstractOpen access mass spectrometry now provides the opportunity to move this spectroscopic method to the beginning of the analytical chain, a place formerly the exclusive province of NMR and TLC. To date this transition has been occurring in industrial settings but there has been less change in the academic environment. This paper provides one blueprint for setting up such a facility, primarily in support of organic synthesis but also for the use of biological scientists. The open access format used at UCI utilizes four instruments: an ESI‐TOFMS system used in the flow injection mode, two GC/MS systems (one in EI and one in CI) and a MALDI‐TOFMS system. The first three instruments have autosamplers and open access software whereas the MALDI system has a fully automated plate handling interface. This level of automation allows access to the instruments by a user community of more than 100 users, day or night. The decisions made in setting up these instruments were based on a ‘keep it simple’ philosophy, given the fact that the primary type of data of interest is the molecular mass of the analyte and that data are required for a very wide range of structures. Copyright © 2002 John Wiley & Sons, Ltd.
Hepatocyte growth factor stimulates the proliferation and migration of oligodendrocyte precursor cells
Authors: Yan Henglin , Rivkees Scott A. 
Published: September 2002

AbstractHepatocyte growth factor (HGF) was initially identified as a potent mitogen for mature hepatocytes and has since been found to affect a variety of cells. Evidence suggests that HGF may also influence the nervous system, in that HGF stimulates the proliferation of myelin‐forming Schwann cells and olfactory ensheathing cells. However, it is not known whether HGF influences oligodendrocytes. To address this issue, oligodendrocyte precursors were obtained from neonatal rat cerebra and cultured. Immunostaining and Western blotting revealed expression of both HGF and the HGF receptor (c‐Met) by cultured oligodendrocytes. When the ability of HGF to stimulate oligodendrocyte division and migration was examined, we observed that treatment with HGF (10–50 ng/ml) elicited twofold increases in oligodendrocyte precursor proliferation. HGF also enhanced oligodendrocyte precursor migration, with 2.5‐fold increases in rates of migration seen after treatment for 8 hr. HGF also influenced inducing the oligodendrocyte cytoskeleton by altering patterns of F‐actin and β‐tubulin distribution and enhanced the expression of actin and β‐tubulin. These observations show that a functional HGF/c‐Met system is present in oligodendrocytes, which can influence the growth, development, and cytoskeletal organization of oligodendrocytes. © 2002 Wiley‐Liss, Inc.
Alterations in matrix metalloproteinase‐9 levels and tissue inhibitor of matrix metalloproteinases‐1 expression in a transforming growth factor‐β transgenic model of hydrocephalus
Authors: Zechel Jennifer , Gohil Harsh , Lust W. David , Cohen Alan 
Published: September 2002

AbstractThe development of spontaneous hydrocephalus in mouse models resulting from the overexpression of transforming growth factor‐β (TGFβ‐1) has been previously described, although the mechanism by which this occurs remains obscure. It has been previously demonstrated that increased expression of TGFβ has consequences for the levels of matrix metalloproteinases (MMPs) and their specific inhibitors (tissue inhibitors of MMPs, or TIMPs). These remodeling proteins play an important role in extracellular matrix (ECM) maintenance through degradation and deposition of ECM components. The present study investigated the relationship between elevated levels of TGFβ‐1, the ECM modulators TIMP‐1 and MMP‐9, and development of hydrocephalus in the neonatal mouse. In newborn pups, TIMP‐1 mRNA levels were equal between animals expressing the TGFβ‐1 transgene and littermates without the transgene. However, immunohistochemistry of littermate pups shows that the distribution of TIMP‐1 was changed from homogeneous with large punctate concentrations of signal to uniform, dense staining in hydrocephalic animals carrying the TGFβ‐1 transgene. The mRNA levels of MMP‐9 were decreased in the transgenic animals, as were the activity levels MMP‐9. These results suggest that the remodeling protein MMP‐9 and its specific inhibitor, TIMP‐1, may contribute to the spontaneous development of hydrocephalus in this transgenic model by altering the ECM environment. © 2002 Wiley‐Liss, Inc.
Analysis of neuronal gene expression with laser capture microdissection
Authors: Vincent Valerie A.M. , DeVoss Jason J. , Ryan Heather S. , Murphy Greer M. 
Published: September 2002

AbstractThe brain is a heterogeneous tissue in which the numbers of neurons, glia, and other cell types vary among anatomic regions. Gene expression studies performed on brain homogenates yield results reflecting mRNA abundance in a mixture of cell types. Therefore, a method for quantifying gene expression in individual cell populations would be useful. Laser capture microdissection (LCM) is a new technique for obtaining pure populations of cells from heterogeneous tissues. Most studies thus far have used LCM to detect DNA sequences. We developed a method to quantify gene expression in hippocampal neurons from mouse brain using LCM and real‐time reverse transcriptase‐polymerase chain reaction (RT‐PCR). This method was optimized to permit histochemical or immunocytochemical visualization of nerve cells during LCM while minimizing RNA degradation. As an example, gene expression was quantified in hippocampal neurons from the Tg2576 mouse model for Alzheimer's disease. © 2002 Wiley‐Liss, Inc.
Malignant rhabdoid tumor shows incomplete neural characteristics as revealed by expression of SNARE complex
Authors: Yoshida Shinobu , Narita Tsutomu , Taga Takashi , Ohta Shigeru , Takeuchi Yoshihiro 
Published: September 2002

AbstractTo elucidate the biological differences in neural phenotype between malignant rhabdoid tumor (MRT) and neuroblastoma cell lines, we examined the expression of solube N‐ethylmaleimide‐sensitive fusion protein attachment protein receptor (SNARE) complex proteins in MRT cell lines under differentiation induction with 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA). Six MRT cell lines (TM87‐16, STM91‐01, TTC642, TTC549, YAM‐RTK1, and TTC1240) and six neuroblastoma cell lines (IMR‐32, NH12, SCCH26, TGW, NB‐1, and NB‐NR) were used in this study. Expression of SNAREs: the vesicle SNARE (synaptotagmin, synaptophysin, and synaptobrevin‐2) and the target SNARE (syntaxin 1A, SNAP‐25A/B) was examined. Our results showed that in MRT cells, only two cell lines (TM87‐16, TTC642) expressed the vesicle SNARE and the target SNARE with the exception of SNAP‐25B, while all neuroblastoma cells expressed the entire SNARE complex. During differentiation, synaptotagmin was upregulated in these two MRT cell lines. Interestingly, synaptophysin was downregulated in these MRT cell lines in contrast with the neuroblastoma cell lines. SNAP‐25B was not expressed in MRT cells after differentiation with TPA. MRT cells having a neural phenotype morphologically looked like neuroblastoma cells after treatment with TPA. However, the expression of SNARE complex was incomplete in MRT cells. Our results suggest that the biological characteristics of MRT cells with neural phenotype are distinct from those of neuroblastoma cells. © 2002 Wiley‐Liss, Inc.
Characterization of cholera toxin B subunit‐induced Ca2+ influx in neuroblastoma cells: Evidence for a voltage‐independent GM1 ganglioside‐associated Ca2+ channel
Authors: Fang Yu , Xie Xin , Ledeen Robert W. , Wu Gusheng 
Published: September 2002

AbstractThe role of endogenous GM1 ganglioside in neurite outgrowth has been studied in N18 and NG108‐15 neuroblastoma cells with the GM1‐specific ligand cholera toxin B subunit (Ctx B), which stimulates Ca2+ influx together with neuritogenesis. Our primary goal has been to identify the nature of the calcium channel that is modulated by GM1. An L‐type voltage‐operated Ca2+ channel (VOCC) was previously proposed as the mediator of this phenomenon. This investigation, employing fura‐2 fluorescent measurements and specific channel blockers and other agents, revealed that GM1 modulates a hitherto unidentified Ca2+ channel not of the L type. It was opened by Ctx B; was permeable to Ca2+ and Ba2+ but not Mn2+; and was blocked by Ni2+, Cd2+, and La3+. Although most dihydropyridines inhibited Ctx B‐induced Ca2+ influx as well as neurite outgrowth at higher concentrations, they and other VOCC blockers at normally employed concentrations failed to do so, suggesting uninvolvement of VOCC. In addition, Ca2+ influx induced by Ctx B was not mediated by cGMP‐dependent or G‐protein‐coupled nonselective cation channels, as demonstrated by the cGMP antagonist Rp‐cGMPS or the G‐protein/receptor uncoupling agent suramin, respectively. Finally, Ca2+ influx was unlikely to be due to inhibition or reversal of Na+‐Ca2+ exchanger via Ctx B induction of Na+ uptake, insofar as no effect was seen on blocking Na+ channels, inhibiting Na+‐K+‐ATPase, or eliminating extracellular Na+. The results suggest that this novel channel is gated by interaction with GM1, which, when associated with the channel and bound by appropriate ligand, promotes Ca2+ influx. This in turn induces signaling for the onset of neuritogenesis. © 2002 Wiley‐Liss, Inc.
Human bone marrow stromal cell cultures conditioned by traumatic brain tissue extracts: Growth factor production
Authors: Chen Xiaoguang , Katakowski Mark , Li Yi , Lu Dunyue , Wang Lei , Zhang Lijie , Chen Jieli , Xu Yongxian , Gautam Subhash , Mahmood Asim , Chopp Michael 
Published: September 2002

AbstractTreatment of traumatic brain injury (TBI) with bone marrow stromal cells (MSCs) improves functional outcome in the rat. However, the specific mechanisms by which introduced MSCs provide benefit remain to be elucidated. Currently, the ability of therapeutically transplanted MSCs to replace injured parenchymal CNS tissue appears limited at best. Tissue replacement, however, is not the only possible compensatory avenue in cell transplantation therapy. Various growth factors have been shown to mediate the repair and replacement of damaged tissue, so trophic support provided by transplanted MSCs may play a role in the treatment of damaged tissue. We therefore investigated the temporal profile of various growth factors, brain‐derived neurotrophic factor (BDNF), nerve growth factor (NGF), vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and hepatocyte growth factor (HGF), within cultures of human MSCs (hMSCs) conditioned with cerebral tissue extract from TBI. hMSCs were cultured with TBI extracts of rat brain in vitro and quantitative sandwich enzyme‐linked immunosorbent assays (ELISAs) were performed. TBI‐conditioned hMSCs cultures demonstrated a time‐dependent increase of BDNF, NGF, VEGF, and HGF, indicating a responsive production of these growth factors by the hMSCs. The ELISA data suggest that transplanted hMSCs may provide therapeutic benefit via a responsive secretion of an array of growth factors that can foster neuroprotection and angiogenesis. © 2002 Wiley‐Liss, Inc.