bluuebunny/crossref_metadata_2025_split huggingface dataset:
Controlling matrix suppression for matrix‐assisted laser desorption/ionization analysis of small molecules
Authors: Donegan Michael , Tomlinson Andy J. , Nair Hari , Juhasz Peter 
Published: July 2004

AbstractThe need for high‐throughput methodologies providing both qualitative and quantitative information has grown substantially in the pharmaceutical laboratory in recent years. Currently, tandem mass spectrometry (MS/MS) using quadrupole technology offers analysis in the minutes time scale. The use of matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) offers the advantage of speed and automation and enables analysis in the seconds time scale with accurate mass capabilities that are not typically found in quadrupole MS/MS. However, one of the limitations of MALDI for the analysis of small molecules is the abundance of interfering matrix peaks in the low molecular weight region of the mass spectrum. Described herein is an evaluation of a pre‐prepared MALDI target plate that has been coated with a thin layer of α‐cyano‐4‐hydroxycinnamic acid (CHCA) and nitrocellulose. This modified plate has been shown to suppress or eliminate CHCA matrix signals without any significant loss of analyte sensitivity when compared with analysis of the same sample using an unmodified target plate. Copyright © 2004 John Wiley & Sons, Ltd.
Investigation of non‐covalent interactions between paramagnetic complexes and human serum albumin by electrospray mass spectrometry
Authors: Henrotte Virginie , Laurent Sophie , Gabelica Valérie , Elst Luce Vander , Depauw Edwin , Muller Robert N. 
Published: July 2004

AbstractStable gadolinium(III) chelates are nowadays routinely used as contrast agents for magnetic resonance imaging (MRI). Their non‐covalent binding to human serum albumin (HSA) has shown to improve their efficacy. Non‐covalent interactions lead to complex formation that can be quantified by several techniques that are mostly tedious and time‐consuming. In this study, electrospray ionization mass spectrometry (ESI‐MS) was used to investigate the interaction between HSA and several gadolinium(III) complexes. The results were compared with those obtained in the liquid phase. Four gadolinium complexes were investigated: Gd‐DTPA 1, Gd‐C4Me‐DTPA 2, Gd‐EOB‐DTPA 3, and MP‐2269 4. Relaxometry studies show that complexes 1 and 2 have no significant affinity for HSA, while complexes 3 and 4 have increasing affinities for the protein. 1:1 and 1:2 complexes between HSA and MP‐2269 were detected by ESI‐MS for a twofold excess of the contrast agent, whereas a ligand/protein molar ratio of 4:1 was necessary to observe a 1:1 stoichiometry for Gd‐EOB‐DTPA, an observation that is in good agreement with the known weaker affinity of the contrast agent for the protein. At a fourfold molar excess, no supramolecular complex was observed for Gd‐DTPA 1 and Gd‐C4Me‐DTPA 2; a tenfold molar excess was necessary to detect a 1:1 complex, confirming the very weak affinity of these contrast agents for HSA. Copyright © 2004 John Wiley & Sons, Ltd.
Chronic immobilization stress differentially affects the expression of BDNF mRNA and protein in the mouse hippocampus
Authors: Adlard Paul A. , Perreau Victoria M. , Cotman Carl W. 
Published: July 2004

AbstractStress impacts multiple systems within the CNS, including the hippocampus. A key molecular mediator in hippocampal functions, including learning and memory, is brain‐derived neurotrophic factor (BDNF). BDNF mRNA is reported to be decreased following chronic (every day) immobilization stress (CIS) in the rat, however the effect on protein is unknown. Utilizing a mouse model of CIS, the hypothesis that total hippocampal BDNF protein, in addition to BDNF mRNA, would be decreased was tested. The effects of intermittent (alternating day) immobilization and cold stress on hippocampal BDNF protein levels was also examined.In this study it was demonstrated that CIS results in a small (8 per cent decrease relative to non‐stressed controls), but significant (p = 0.0013) decrease in the exon coding for mature BDNF (exon VI). In addition, there was a significant (34 per cent, p = 0.005) decrease in the mRNA coding for exon I in the stressed animals. Contrary to expectations, however, CIS resulted in a significant (116 per cent, p = 0.0087) increase in hippocampal BDNF protein levels. Furthermore, both intermittent immobilization and chronic cold stress both increased BDNF protein levels. Chronic stress, therefore, differentially regulates BDNF mRNA and protein levels in the hippocampus. Copyright © 2004 John Wiley & Sons, Ltd.
A cultural perspective of the induction of five reform‐minded beginning mathematics and science teachers
Authors: McGinnis J. Randy , Parker Carolyn , Graeber Anna O. 
Published: July 2004

AbstractThe purpose of this empirical study was to present a detailed description and interpretation of what happens in schools to beginning teachers who are prepared to enact reform‐based practices in mathematics and science. The focus was on a select sample of graduates from the Maryland Collaborative for Teacher Preparation [MCTP], a statewide reform‐based undergraduate teacher preparation program funded by the National Science Foundation. Interpretative research methodology was used to conduct a cultural case study of the beginning teachers' first 2 years of practice (first year, N = 5; second year, N = 3). We documented differential experiences and perceptions of the beginning teachers from both inside (emic) and outside (etic) perspectives. Documented discussion centered on an analytical framework suggested elsewhere. Findings were framed in two components: the individual's intentions, needs, and capabilities; and the institutional demands, affordances, and constraints. The major insight was that the beginning teachers' perception of their school culture was a major factor in whether reform‐aligned mathematics and science teaching was regularly implemented by the beginning teachers. In instances where the beginning teachers' perceived that their school cultures offered a lack of support for their intent to implement reform‐based practices the beginning teachers exhibited differing social strategies (resistance, moving on, and exit). Therefore, to sustain reform (and, by extension, to retain beginning mathematics and science teachers), a key implication is to place additional attention on the use of the school culture perspective to improve teacher preparation and induction experiences. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 720–747, 2004
Young children's emotional practices while engaged in long‐term science investigation
Authors: Zembylas Michalinos 
Published: July 2004

AbstractIn this article, the role of young children's emotional practices in science learning is described and analyzed. From the standpoint of performativity theory and social‐constructionist theory of emotion, it is argued that emotion is performative and the expression of emotion in the classroom has its basis in social relationships. Arising from these relationships is the emotional culture of the classroom that plays a key role in the development of classroom emotional rules as well as the legitimation of science knowledge. These relationships are reflected in two levels of classroom dialogue: talking about and doing science, and expressing emotions about science and its learning. The dynamics of the negotiations of classroom emotional rules and science knowledge legitimation may dispose students to act positively or negatively toward science learning. This analysis is illustrated in the experiences of a teacher and her students during a 3‐year ethnographic study of emotions in science teaching and learning. This research suggests the importance of the interrelationship between emotions and science learning and the notion that emotional practices can be powerful in nurturing effective and exciting science learning environments. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 693–719, 2004
Efficient gene targeting in Kluyveromyces lactis
Authors: Kooistra Rolf , Hooykaas Paul J. J. , Steensma H. Yde 
Published: July 2004

AbstractIntegration of a DNA fragment in a host genome requires the action of a double‐strand break (DSB) repair mechanism. Homologous recombination (HR) is initiated by binding of Rad52p to DNA ends and results in targeted integration. Binding of the Ku heterodimer (Ku70p/Ku80p) results in random integration via non‐homologous end joining (NHEJ). In contrast to Saccharomyces cerevisiae, the budding yeast Kluyveromyces lactis shows variable, but in general low, gene targeting efficiency. To study and to improve gene targeting efficiency, K. lactis has been used as a model. The KlRAD51, KlRAD52 and KlKU80 genes have been isolated and deletion mutants for these genes have been constructed. Efficiency of gene targeting was determined at the KlADE2 locus using targeting constructs with different lengths of homologous flanking sequences. In wild‐type K. lactis, the gene targeting efficiency ranged from 0% with 50 to 88% with 600 bp flanks. The Klku80 mutant, however, showed >97% gene targeting efficiency independently of the size of the homologous flanks. These results demonstrate that deletion of the NHEJ mechanism results in a higher gene targeting efficiency. Furthermore, increased gene targeting efficiency was achieved by the transformation of wild‐type K. lactis with the KlADE2 deletion construct in the presence of excess small DNA fragments. Using this method, PCR‐generated deletion constructs containing only 50 bp of homologous flanking sequences resulted in efficient targeted gene replacement. Copyright © 2004 John Wiley & Sons, Ltd.
Localization of proteins that are coordinately expressed with Cln2 during the cell cycle
Authors: Sundin Bryan A. , Chiu Chun‐Hwei , Riffle Michael , Davis Trisha N. , Muller Eric G. D. 
Published: July 2004

AbstractThe localization of proteins can give important clues about their function and help sort data from large‐scale proteomic screens. Forty‐five proteins were tagged with the GFP variant YFP. These proteins were chosen because they are encoded by genes that display strong cell cycle‐dependent expression that peaks in G1. Most of these proteins localize to either the nucleus or to sites of cell growth. We are able to assign new cellular component GO terms to ASF2, TOS4, RTT109, YBR070C, YKR090W, YOL007C, YOL019W and YPR174C. We also have localization data for 21 other proteins. Noteworthy localizations were found for Rfa1p, a member of the DNA replication A complex, and Pri2p and Pol12p, subunits of the α‐DNA polymerase : primase complex. In addition to its nuclear localization, Rfa1p assembled into cytoplasmic foci adjacent to the nucleus in cells during the G1–S phase transition of the cell cycle. Pri2 and Pol12 took on a beaded appearance at the G1–S transition and later in the cell cycle were enriched in the nuclear envelope. A new spindle pole body/nuclear envelope component encoded by YPR174 was identified. The cell cycle‐dependent abundance of Tos4p mirrored Yox1p and these two proteins were the only proteins that were found exclusively at the G1–S phase of the cell cycle. A complete list of localizations, along with images, can be found at our website (http://www.yeastrc.org/cln2/). Copyright © 2004 John Wiley & Sons, Ltd.
Phenotypic characterization of glucose repression mutants of Saccharomyces cerevisiae using experiments with 13C‐labelled glucose
Authors: Raghevendran Vijayendran , Gombert Andreas Karoly , Christensen Bjarke , Kötter Peter , Nielsen Jens 
Published: July 2004

AbstractIn the field of metabolic engineering and functional genomics, methods for analysis of metabolic fluxes in the cell are attractive as they give an overview of the phenotypic response of the cells at the level of the active metabolic network. This is unlike several other high‐throughput experimental techniques, which do not provide information about the integrated response a specific genetic modification has on the cellular function. In this study we have performed phenotypic characterization of several mutants of the yeast Saccharomyces cerevisiae through the use of experiments with 13C‐labelled glucose. Through GC–MS analysis of the 13C incorporated into the amino acids of cellular proteins, it was possible to obtain quantitative information on the function of the central carbon metabolism in the different mutants. Traditionally, such labelling data have been used to quantify metabolic fluxes through the use of a suitable mathematical model, but here we show that the raw labelling data may also be used directly for phenotypic characterization of different mutant strains. Different glucose derepressed strains investigated employed are the disruption mutants reg1, hxk2, grr1, mig1 and mig1mig2 and the reference strain CEN.PK113‐7D. Principal components analysis of the summed fractional labelling data show that deleting the genes HXK2 and GRR1 results in similar phenotype at the fluxome level, with a partial alleviation of glucose repression on the respiratory metabolism. Furthermore, deletion of the genes MIG1, MIG1/MIG2 and REG1 did not result in a significant change in the phenotype at the fluxome level. Copyright © 2004 John Wiley & Sons, Ltd.
Differential expression and localization of CFTR and ENaC in mouse endometrium during pre‐implantation
Authors: Yang Jian Zhi , Ajonuma Louis Chukwuemeka , Tsang Lai Ling , Lam Sun Yee , Rowlands Dewi Kenneth , Ho Lok Sze , Zhou Chen Xi , Chung Yiu Wa , Chan Hsiao Chang 
Published: July 2004

AbstractInteraction between the cystic fibrosis transmembrane conductance regulator (CFTR), a CAMP‐activated Cl− channel, and epithelial Na+ channel (ENaC) has been proposed as the major mechanism regulating uterine fluid absorption and secretion. Differential expression of these ion channels may give rise to dynamic changes in the fluid environment affecting various reproductive events in the female reproductive tract. This study investigated the expression and localization of CFTR and ENaC during the pre‐implantation period. Semi‐quantitative reverse transcriptase polymerase chain reaction and immunohistochemistry were used to study the expression and localization of CFTR and ENaC in uteri collected from mature superovulated female mice. RT‐PCR showed maximal ENaC and CFTR expression on day 3 after mating. Maximal immunoreactivity was also observed for both ENaC and CFTR on day 3 after mating. However, ENaC was immunolocalized to the apical membrane of both luminal and glandular epithelia, while CFTR was predominantly found in the stromal cells rather than the epithelial cells. Differential expression and localization of CFTR and ENaC provide a molecular mechanism by which maximal fluid absorption can be achieved immediately prior to implantation, to ensure the immobilization of the blastocyst necessary for implantation.
Evidence for the involvement of endogenous ATP and P2X receptors in TMJ pain
Authors: Oliveira Maria Cláudia G. , Parada Carlos Amílcar , Veiga Maria Cecília Ferraz Arruda , Rodrigues Luciane Rocha , Barros Silvana Pereira , Tambeli Cláudia Herrera 
Published: July 2004

AbstractEvidence is accumulating which supports a role for ATP in the initiation of pain by acting on P2X receptors expressed on nociceptive afferent nerve terminals. To investigate whether these receptors play a role in temporomandibular (TMJ) pain, we studied the presence of functional P2X receptors in rat TMJ by examining the nociceptive behavioral response to the application of the selective P2X receptor agonist α,β‐methylene ATP (α,β‐meATP) into the TMJ region of rat. The involvement of endogenous ATP in the development of TMJ inflammatory hyperalgesia was also determined by evaluating the effect of the general P2 receptor antagonist pyridoxal‐phosphate‐6‐azophenyl‐2′,4′‐disulphonic acid (PPADS) on carrageenan‐induced TMJ inflammatory hyperalgesia. Application of α,β‐meATP into the TMJ region of rats produced significant nociceptive responses that were significantly reduced by the co‐application of lidocaine N‐ethyl bromide quaternary salt, QX‐314, (2%) or of the P2 receptor antagonist PPADS. Co‐application of PPADS with carrageenan into the TMJ significantly reduced inflammatory hyperalgesia. The results indicate that functional P2X receptors are present in the TMJ and suggest that endogenous ATP may play a role in TMJ inflammatory pain mechanisms possibly by acting primarily in these receptors.
Endovascular coil embolization of residual or recurrent aneurysms after surgical clipping
Authors: Cekirge H.S. , Islak C. , Firat M.M. , Kocer N. , Saatci I. 
Published: July 2004

Purpose: Treatment of residual or recurrent aneurysms after surgical clipping is a challenge and most surgeons prefer to avoid a second surgical attempt. We present treatment of 4 residual or recurrent aneurysms after surgical clipping with electrolytically detachable coils. Material and Methods: In 3 of 4 patients, recurrent aneurysms were diagnosed with angiography 2 months, 5 years and 14 years after surgery, although the domes of the aneurysms were opened following clipping during the surgery. In the 4th patient, an early postoperative angiogram revealed filling of a residual aneurysm secondary to the incomplete neck clipping. Guglielmi detachable coils were used to occlude the residual or recurrent aneurysm. Results: The endovascular approach was successful in all patients and the control angiograms showed complete obliteration of the aneurysms with no recanalization. Conclusion: The endovascular approach is a good treatment option for patients in whom complete obliteration of the aneurysm cannot be achieved by surgical clipping. Opening of the aneurysm sac after clipping does not necessarily preclude aneurysm regrowth from a neck remnant proximal to the clip.
Evaluation of new sclerotic bone metastases in breast cancer patients during treatment
Authors: Çiray I. , Åström G. , Andréasson I. , Edekling T. , Hansen J. , Bergh J. , Ahlström H. 
Published: July 2004

Purpose: According to the World Health Organization (WHO) criteria for response of bone metastases to therapy, new lesions indicate progressive disease. We intended to prove that a new sclerotic lesion on conventional radiography may also be a sign of a positive therapeutic response in a previously undetectable lytic metastasis. Material and Methods: In a previous placebo-controlled clinical trial of clodronate (Ostac) therapy, 139 breast cancer patients with bone metastases underwent both conventional radiography and bone scan every 6 months for 2 years with 99mTc before and during clodronate treatment. WHO criteria were applied for therapy response evaluation. Results: In 24 patients, 52 new sclerotic lesions observed during therapy were selected for re-evaluation of conventional radiographs and bone scans. In 8 of the 24 patients, 17 of 52 new sclerotic lesions (33%) had showed positive uptake on previous bone scans. These lesions were possibly misinterpreted as new when applying WHO criteria. Conclusion: For better assessment of new sclerotic lesions during treatment, more sensitive techniques, e.g. bone scan, are needed as a complement to conventional radiography.
Imaging of aortoiliac arterial disease: Duplex ultrasound and MR angiography versus digital subtraction angiography
Authors: Lundin P. , Svensson Å. , Henriksen E. , Jonason T. , Forssell C. , Bäckbro B. , Bodlund M. , Ringqvist I. 
Published: July 2004

Purpose: To evaluate and compare the diagnostic accuracy of duplex ultrasound (US) and MR angiography (MRA) at 1.0 T in aortoiliac arterial disease using digital subtraction angiography (DSA) as the reference standard. In addition, a comparison of the 2D time-of flight (TOF) and 3D contrast-enhanced MRA (CE MRA) techniques was performed. Material and Methods: Prospectively, 39 patients with symptoms of lower-extremity arterial occlusive disease were examined using US, TOF MRA, CE MRA and DSA. Significant lesions (stenosis ≥50%) and occlusions were evaluated blindly for each method. Results: For all segments, the sensitivity for US, TOF MRA and CE MRA with regard to significant lesions was 0.72, 0.81 and 0.81, respectively, and the specificity for each was 0.97, 0.91 and 0.92, respectively. For significant lesions above the inguinal ligament the corresponding sensitivity was 0.84, 0.89 and 0.94 and the specificity 0.93, 0.82 and 0.73, respectively. The specificity was higher when the two MRA methods were combined. TOF MRA overgraded 7 segments as occluded. In most cases, the length of the occlusions was correctly determined on CE MRA, overestimated on TOF MRA and uncertain on US. Conclusion: Neither US nor MRA were sufficiently accurate to fully replace angiography. MRA was preferable to US as a non-invasive test when vascular intervention was contemplated. Although CE MRA was superior to TOF MRA, the most accurate results were achieved when the two methods were combined.
Bread and barium: Diagnostic value in patients with suspected primary esophageal motility disorders
Authors: Nellemann H. , Aksglaede K. , Funch-Jensen P. , Thommesen P. 
Published: July 2004

Purpose: To evaluate the significance of bread and barium studies as a diagnostic tool as well as a supplement to manometric investigation of the esophagus in patients with suspected esophageal motility disorders. Material and Methods: Eighty-nine patients suspected for primary esophageal motility disorders were examined. All patients were interviewed before the investigation to determine the prevalence of symptoms like heartburn, chest pain, and dysphagia. The patients underwent simultaneous roentgenologic and manometric investigations in the supine position during wet and solid barium swallow, and during continuous drinking, followed by investigation for gastroesophageal reflux (GER). The manometric examination was performed with triple-lumen catheters connected to a hydraulic capillary infusion system and external transducers. Results: All patients with normal esophageal clearing (n=31) had normal manometry. Patients with delayed esophageal clearing (n=58) required manometry for identifying concommittant motility disorders; achalasia and diffuse esophageal spasms were found only in patients with delayed liquid and solid emptying. GER and/or esophageal rings was demonstrated in 31 patients. Conclusion: We suggest bread and barium as the first diagnostic step in patients with clinical suspicion of primary esophageal motility disorders.
Dynamic MR imaging of liver metastases with Gd-EOB-DTPA
Authors: Stern W. , Schick F. , Kopp A.F. , Reimer P. , Shamsi K. , Claussen C.D. , Laniado M. 
Published: July 2004

Purpose: To assess liver and lesion enhancements by dynamic MR imaging after bolus injection of the hepatobiliary contrast agent gadolinium ethoxybenzyldiethylenetriamine-pentaacetic acid (Gd-EOB-DTPA) in patients with liver metastases and to compare the effect of different doses. Material and Methods: A randomized double-blinded trial with doses of 12.5, 25 and 50 µmol/kg Gd-EOB-DTPA was performed in 35 patients with liver metastases. Liver enhancement, tumor enhancement and liver lesion contrast-to-noise (C/N) ratios were calculated from breath-hold gradient echo images (100/5/80°) recorded precontrast and at different times up to 10 min postcontrast. Results: Normal liver showed a characteristic enhancement pattern, with a rapid enhancement in the first 45 s postcontrast and a slight but significant further increase up to 600 s. The initial enhancement in the lesions was also pronounced, but the enhancement was slightly decreased after 240 s postcontrast. At dose levels of 12.5 and 25 µmol/kg Gd-EOB-DTPA, C/N ratios significantly increased compared to baseline from 90 to 600 s. Postcontrast C/N-values obtained using 50 µmol/kg Gd-EOB-DTPA were not significantly increased, except for the examinations 480 s postcontrast. Conclusion: In liver metastases, C/N ratios obtained with doses of 12.5 and 25 µmol/kg Gd-EOB-DTPA were slightly superior to 50 µmol/kg Gd-EOB-DTPA. This finding is probably due to a more pronounced extracellular effect of the contrast medium at higher doses.