bluuebunny/crossref_metadata_2025_split huggingface dataset:
Susceptibility weighted imaging at ultra high magnetic field strengths: Theoretical considerations and experimental results
Authors: Deistung Andreas , Rauscher Alexander , Sedlacik Jan , Stadler Jörg , Witoszynskyj Stephan , Reichenbach Jürgen R. 
Published: October 2008

AbstractWe present numerical simulations and experimental results for susceptibility weighted imaging (SWI) at 7 T. Magnitude, phase, and SWI contrast were simulated for different voxel geometries and imaging parameters, resulting in an echo time of 14 msec for optimum contrast between veins and surrounding tissue. Slice thickness of twice the in‐plane voxel size or more resulted in optimum vessel visibility. Phantom and in vivo data are in very good agreement with the simulations and the delineation of vessels at 7 T was superior compared to lower field strengths. The phase of the complex data reveals anatomical details that are complementary to the corresponding magnitude images. Susceptibility weighted imaging at very high field strengths is a promising technique because of its high sensitivity to tissue susceptibility, its low specific absorption rate, and the phase's negligible sensitivity to B1 inhomogeneities. Magn Reson Med 60:1155–1168, 2008. © Wiley‐Liss, Inc.
On the overestimation of early wall thickening at the carotid bulb by black blood MRI, with implications for coronary and vulnerable plaque imaging
Authors: Antiga L. , Wasserman B.A. , Steinman D.A. 
Published: October 2008

AbstractBlack blood MRI is an attractive tool for monitoring normal and pathological wall thickening; however, limited spatial resolutions can conspire with complex vascular geometries to distort the appearance of the wall in ways hitherto unclear. To elucidate this, a thin‐walled cylinder model was developed to predict the composite effects of obliqueness, in‐plane resolution and voxel anisotropy on the accuracy of MRI‐derived wall thickness measurements. These predictions were validated by means of imaging of a thin‐walled carotid bifurcation phantom. Typical thick‐slice axial acquisitions were found to result in artifactual wall thickening at the carotid bulb, owing to its obliqueness to the nominal imaging plane. Obliqueness was less problematic for near‐isotropic resolutions; however, the obligatory reduction of in‐plane resolution served to inflate wall thicknesses uniformly by up to 50%. Moreover, the nonlinear relationship between wall thickness and its overestimation served to mask genuine differences in wall thickness, an effect predicted to be worse for thinner coronary artery walls and plaque caps. Therefore, care must be taken when interpreting black blood MRI wall thickness measurements in the presence—or absence—of observed differences within or between individuals. Magn Reson Med 60:1020–1028, 2008. © 2008 Wiley‐Liss, Inc.
Highly k‐t‐space–accelerated phase‐contrast MRI
Authors: Jung Bernd , Honal Matthias , Ullmann Peter , Hennig Jürgen , Markl Michael 
Published: October 2008

AbstractThe purpose of this study was to combine a recently introduced spatiotemporal parallel imaging technique, PEAK‐GRAPPA (parallel MRI with extended and averaged generalized autocalibrating partially parallel acquisition), with two‐dimensional (2D) cine phase‐contrast velocity mapping. Phase‐contrast MRI was applied to measure the blood flow in the thoracic aorta and the myocardial motion of the left ventricle. To evaluate the performance of different reconstruction methods, fully acquired k‐space data sets were used to compare conventional parallel imaging using GRAPPA with reduction factors of R = 2–6 and PEAK‐GRAPPA as well as sliding window reconstruction with reduction factors R = 2–12 (net acceleration factors up to 5.2). PEAK‐GRAPPA reconstruction resulted in improved image quality with considerably reduced artifacts, which was also supported by error analysis. To analyze potential blurring or low‐pass filtering effects of spatiotemporal PEAK‐GRAPPA, the velocity time courses of aortic flow and myocardial tissue motion were evaluated and compared with conventional image reconstructions. Quantitative comparisons of blood flow velocities and pixel‐wise correlation analysis of velocities highlight the potential of PEAK‐GRAPPA for highly accelerated dynamic phase‐contrast velocity mapping. Magn Reson Med 60:1169–1177, 2008. © 2008 Wiley‐Liss, Inc.
Quantitative 2D and 3D phase contrast MRI: Optimized analysis of blood flow and vessel wall parameters
Authors: Stalder A.F. , Russe M.F. , Frydrychowicz A. , Bock J. , Hennig J. , Markl M. 
Published: October 2008

AbstractQuantification of CINE phase contrast (PC)‐MRI data is a challenging task because of the limited spatiotemporal resolution and signal‐to‐noise ratio (SNR). The method presented in this work combines B‐spline interpolation and Green's theorem to provide optimized quantification of blood flow and vessel wall parameters. The B‐spline model provided optimal derivatives of the measured three‐directional blood velocities onto the vessel contour, as required for vectorial wall shear stress (WSS) computation. Eight planes distributed along the entire thoracic aorta were evaluated in a 19‐volunteer study using both high‐spatiotemporal‐resolution planar two‐dimensional (2D)‐CINE‐PC (∼1.4 × 1.4 mm2/24.4 ms) and lower‐resolution 3D‐CINE‐PC (∼2.8 × 1.6 × 3 mm3/48.6 ms) with three‐directional velocity encoding. Synthetic data, error propagation, and interindividual, intermodality, and interobserver variability were used to evaluate the reliability and reproducibility of the method. While the impact of MR measurement noise was only minor, the limited resolution of PC‐MRI introduced systematic WSS underestimations. In vivo data demonstrated close agreement for flow and WSS between 2D‐ and 3D‐CINE‐PC as well as observers, and confirmed the reliability of the method. WSS analysis along the aorta revealed the presence of a circumferential WSS component accounting for 10–20%. Initial results in a patient with atherosclerosis suggest the potential of the method for understanding the formation and progression of cardiovascular diseases. Magn Reson Med 60:1218–1231, 2008. © 2008 Wiley‐Liss, Inc.
Prostate cancer stem cells
Authors: Lang SH , Frame FM , Collins AT 
Published: October 2008

AbstractDespite the discovery over 60 years ago by Huggins and Hodges 1 that prostate cancers respond to androgen deprivation therapy, hormone‐refractory prostate cancer remains a major clinical challenge. There is now mounting evidence that solid tumours originate from undifferentiated stem cell‐like cells coexisting within a heterogeneous tumour mass that drive tumour formation, maintain tumour homeostasis and initiate metastases. This review focuses upon current evidence for prostate cancer stem cells, addressing the identification and properties of both normal and transformed prostate stem cells. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Zur Geschichte der Antitussiva und Expektorantien. “Beim Arzte nicht in gutem Rufe”
Authors: Meyer Ulrich 
Published: October 2008

AbstractObwohl die Arzneimittelgeschichte in den letzten Jahrzehnten zu einem wichtigen Arbeitsgebiet der Pharmaziehistoriographie avancierte, ist die Entwicklung, Herstellung und Vermarktung von Expektorantien und Antitussiva vergleichsweise schlecht erforscht.
Physiologie der Atemwege und Hustenarten. Reinigungssystem mit Schutzfunktion
Authors: Weis Günter 
Published: October 2008

AbstractAtmen – die rhythmischen Bewegungen unseres Brustkorbs gewährleisten den lebensnotwendigen Gasaustausch zwischen Atemluft und Blut. Dieser findet in den Lungenbläschen, den Alveolen, statt. Die Fläche der etwa 500 Millionen Alveolen, die die Grenzfläche zwischen Luft und Blut bilden, ist beim Erwachsenen so groß wie ein Tennisplatz.
Beratung von Hustenpatienten in der Apotheke. Wann ist Selbstmedikation möglich?
Authors: Griese Nina , Schulz Martin 
Published: October 2008

AbstractHusten ist eines der häufigsten Symptome, für das Patienten in der Apotheke ein Präparat der Selbstmedikation wünschen. Die Aufgabe des pharmazeutischen Personals ist es, zu entscheiden, ob eine Selbstmedikation möglich ist oder der Patient zum Arzt verwiesen werden muss. Ist eine Selbstmedikation möglich, ist für die Hustensymptomatik des Patienten das geeignete Arzneimittel auszuwählen. Da die Datenlage für Arzneimittel zur Behandlung des akuten Hustens bei Erwachsenen und Kindern unbefriedigend ist, sind weitere Interventions‐ und Beobachtungsstudien wünschenswert.
Nichtrauchen, ein Essential für eine gesunde Lunge. Raucherentwöhnung ist die wichtigste Präventionsmaßnahme überhaupt
Authors: Schunack Walter 
Published: October 2008

AbstractRauchen ist das größte Einzelrisiko in unserem Leben. Aufgrund des extremen gesundheitlichen Risikos des Rauchens ist die Behandlung der Tabakabhängigkeit die wichtigste Präventionsmaßnahme überhaupt. Für die Verhaltenstherapie wird nach einem Jahr eine Tabak‐Abstinenzrate von ca. 13 % angegeben. Die Abstinenzraten nach einem Jahr betragen für Placebo ca. 8 %, für Nicotinersatztherapie ca. 14 %, für Bupropion ca. 16 % und für Vareniclin ca. 22 %. Damit sind gegenüber Placebo bzw. keiner Medikation die 1‐Jahres‐Abstinenzraten für Nicotinersatztherapie um das ca. 1,8‐fache, für die Behandlung mit Bupropion um das ca. 2‐fache und für die Vareniclin‐Behandlung um das ca. 2,8‐fache erhöht. Durch intensive Beratung des Rauchers können die Abstinenzraten weiter verbessert werden. Alle Neben‐ und Wechselwirkungen sind vor dem Hintergrund zu sehen, dass Weiterrauchen das alles übertreffende Risiko ist. In Deutschland sterben täglich mindestens 300 Menschen an den Folgen des Rauchens.
Assessing balance in measured baseline covariates when using many‐to‐one matching on the propensity‐score
Authors: Austin Peter C. 
Published: October 2008

AbstractThe propensity score is defined to be a subject's probability of treatment selection, conditional on observed baseline covariates. Conditional on the propensity score, treated and untreated subjects have similar distributions of observed baseline covariates. Propensity‐score matching is a commonly used propensity score method for estimating the effects of treatment on outcomes. Balance diagnostics have been previously described for use when 1:1 matching on the propensity score is employed. We illustrate that these methods can be misleading when many‐to‐one matching on the propensity score is employed. We then propose modifications of these methods that involve weighting each untreated subject by the inverse of the number of untreated subjects in the matched set. We describe both quantitative and qualitative methods to assess the balance in baseline covariates between treated and untreated subjects in a sample obtained by many‐to‐one matching on the propensity score. The quantitative method uses the weighted standardized difference. The qualitative methods employ graphical methods to compare the distribution of continuous baseline covariates between treated and untreated subjects in the weighted sample. We illustrate our methods using a large sample of patients discharged from hospital with a diagnosis of a heart attack (acute myocardial infarction). The exposure was receipt of a prescription for a statin at hospital discharge. Copyright © 2008 John Wiley & Sons, Ltd.
Preparation of nanocomposites based on PP and PA6 by direct injection molding
Authors: Frache Alberto , Monticelli Orietta , Ceccia Simona , Brucellaria Alessandro , Casale Antonio 
Published: October 2008

AbstractNanocomposites based on polyamide 6 (PA6) and polypropylene (PP) have been prepared by melt compounding the above polymer matrices with two montmorillonite(MMT)‐type commercial organoclays which, from previous studies of ours and from some results reported in literature, resulted to be the most proper layered silicates to be dispersed in PP and PA6, respectively. The preparation of nanocomposites has followed two different approaches. In the first, melt blending was carried out by twin screw extrusion whereas, direct injection molding was used in the second method. X‐ray diffraction (WAXD) and transmission electron microscope (TEM) characterizations have evidenced that independently of the preparation approach, nanostructured material were obtained, which are intercalated in the case of PP and exfoliated in that of PA6. Also mechanical properties have demonstrated that nanocomposites prepared by applying the two methods were characterized by similar features. These findings demonstrate the effectiveness of direct injection molding in the preparation of nanocomposites, whose features are similar to those prepared by compounding. Indeed, the elongational deformation, applied in the former technique, might favor the clay dispersion in the polymer matrix. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
Property modulation of poly(N‐isopropylacrylamide) hydrogels by incorporation of modified silica
Authors: Ham Myong Jo , Kim Young Ho 
Published: October 2008

AbstractPoly(N‐isopropylacrylamide) (PNIPA)/silica composite hydrogels were prepared and the effects of the silica incorporation on the swelling and breaking characteristics of the hydrogels were investigated. To improve the dispersive property of silica in the PNIPA matrix via the formation of covalent bonds between the polymer and silica, vinyl groups were introduced in the silica by reacting it with a coupling agent, 3‐methacryloxypropyltrimethoxysilane. When unmodified silica was used as filler in the PNIPA‐composite hydrogel, the swelling ratio of the composite hydrogel below the critical gel transition temperature (CGTT) increased with increasing silica content. However, when the modified silica was used as the filler, the swelling ratio below CGTT decreased with increasing silica content because of the enhanced distribution and additional crosslinking. Above CGTT, the swelling ratios of the PNIPA/silica hydrogels were similar regardless of the silica modification. The gel breaking stress of the hydrogels increased with increasing silica content, and this enhancement was larger for the modified silica hydrogel. Scanning electron microscopy images showed that the modified silica particles were distributed more evenly in the PNIPA matrix than the unmodified ones were and that the size of cell‐like structure of the hydrogel decreased with increasing modified silica content. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers
A proteome analysis of the cadmium and mercury response in Corynebacterium glutamicum
Authors: Fanous Ali , Weiss Walter , Görg Angelika , Jacob Fritz , Parlar Harun 
Published: October 2008

AbstractCadmium and mercury are well‐known toxic heavy metals, but the basis of their toxicity is not well understood. In this study, we analyzed the cellular response of Corynebacterium glutamicum to sublethal concentrations of cadmium and mercury ions using 2‐DE and MS. Mercury induced the over‐expression of 13 C. glutamicum proteins, whereas 35 proteins were induced, and 8 proteins were repressed, respectively, under cadmium stress. The principal response to these metals was protection against oxidative stress, as demonstrated by upregulation of, e.g., Mn/Zn superoxide dismutase. Thioredoxin and oxidoreductase responded most strongly to cadmium and mercury. The increased level of heat‐shock proteins, enzymes involved in energy metabolism, as well as in lipoic acid and terpenoid biosynthesis after the treatment of cells with cadmium was also registered. Identification of these proteins and their mapping into specific cellular processes enable a global understanding of the way in which C. glutamicum adapts to heavy‐metal stress and may help to gain deeper insight into the toxic mechanism of these metals.
Application of electron transfer dissociation (ETD) for the analysis of posttranslational modifications
Authors: Wiesner Julia , Premsler Thomas , Sickmann Albert 
Published: October 2008

AbstractDespite major advantages in the field of proteomics, the analysis of PTMs still poses a major challenge; thus far, preventing insights into the role and regulation of protein networks. Additionally, top‐down sequencing of proteins is another powerful approach to reveal comprehensive information for biological function. A commonly used fragmentation technique in MS‐based peptide sequencing is CID. As CID often fails in PTM‐analysis and performs best on doubly‐charged, short and middle‐sized peptides, confident peptide identification may be hampered. A newly developed fragmentation technique, namely electron transfer dissociation (ETD), supports both, PTM‐ and top‐down analysis, and generally results in more confident identification of long, highly charged or modified peptides. The following review presents the theoretical background of ETD and its technical implementation in mass analyzers. Furthermore, current improvements of ETD and approaches for the PTM‐analysis and top‐down sequencing are introduced. Alternating both fragmentation techniques, ETD and CID, increases the amount of information derived from peptide fragmentation, thereby enhancing both, peptide sequence coverage and the confidence of peptide and protein identification.
Torquoselectivity in the electrocyclic ring‐opening of cyclopropyl anions
Authors: Faza Olalla Nieto , López Carlos Silva , Pérez Adán B. González , Rodríguez Martín Pérez , de Lera Ángel Rodríguez 
Published: October 2008

AbstractRing‐opening reactions of substituted cyclopropanes are a convenient synthetic method for the preparation of functionalized alkenes. The Woodward–Hoffmann‐DePuy rule governs the selectivity of the cationic process, as exemplified by the solvolysis of substituted halocyclopropanes but, although the reaction has been studied in detail, the torquoselectivity in the ring‐opening of cyclopropyl anions has never been addressed. In this work, we use DFT calculations to study the two Woodward–Hoffmann allowed ring‐opening paths available to cyclopropyl anions with different substitution patterns. We find that the reaction proceeds with torquoselectivity, evaluate the applicability of Houk's model to explain the effect of the substituents in the product distribution and correlate this effect with the aromaticity of the corresponding transition states. Copyright © 2008 John Wiley & Sons, Ltd.
Molecular engineering of photoactive liquid crystalline polyester epoxies containing benzylidene moiety
Authors: Rao V. Srinivasa , Samui A. B. 
Published: October 2008

AbstractA series of photoactive liquid crystalline polyester epoxies incorporating bisbenzylidene segments as photoactive mesogenic cores were synthesized by polyaddition of diepoxy monomers and terephthalic acid/trimesic acid. To investigate the influence of structural parameters such as, molecular architecture, structural rigidity of mesogenic unit and substituents on thermal, mesogenic, and photoactive properties, the bisbenzylidene segment was incorporated into one acyclic and two cycloalkanone units with two and four substituents, respectively in both linear and hyperbranched architectures. Degree of branching of hyperbranched polymers was found to be in the range of 0.49–0.62. All polymers exhibited nematic mesophase (nematic droplets). Photo induced (2π + 2π) cycloaddition reaction, upon exposure to light at 365 nm, was examined. Inter molecular photocycloaddition was confirmed by photoviscosity measurement of UV irradiated polymer solutions. Faster photo induced reactivity of polymers in hyperbranched architecture was observed when compared to linear structure. Acyclic units facilitated photocycloaddition, and five‐membered ring showed higher photoactivity compared to six‐membered ring. The steric hindrance caused by substituents decreased the photoactivity of polymers. Refractive index change was found to be in the range of 0.015–0.024. Substantial variation of refractive index indicates that these polymers could be used for optical recording. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7637–7655, 2008
Poly(methyl methacrylate) copolymers containing pendant carbazole and oxadiazole moieties for applications in single‐layer organic light emitting devices
Authors: Evanoff David D. , Carroll Joseph B. , Roeder Ryan D. , Hunt Zachary J. , Lawrence Justin R. , Foulger Stephen H. 
Published: October 2008

AbstractMethyl methacrylate derived monomers functionalized with pendant carbazole and oxadiazole moieties were synthesized and could be copolymerized to form a random copolymer. The glass transition temperature of the copolymers could be predicted with a Fox equation and ranged from 140 to 191 °C. The photoluminescent characteristics of the copolymers, both in solution and in solid films, exhibited emission that was a combination of sharp and broad peaks, suggestive of monomeric and chromophore aggregation emission. These trends were also apparent in the electroluminescent response of the copolymers, where the appearance of an electromer emission was evident and was tentatively assigned to the carbazole moieties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7882–7897, 2008
The role of mid‐chain radicals in acrylate free radical polymerization: Branching and scission
Authors: Junkers Tanja , Barner‐Kowollik Christopher 
Published: October 2008

AbstractThe past 5 years have seen a significant increase in the understanding of the fate of so‐called mid‐chain radicals (MCR), which are formed during the free radical polymerization of monomers that form highly reactive propagating radicals and contain an easily abstractable hydrogen atom. Among these monomers, acrylates are, beside ethylene, among the most prominent. Typically, a secondary propagating acrylate‐type macroradical (SPR) can easily transfer its radical functionality via a six‐membered transition state to a position within the polymer chain (in a so‐called backbiting reaction), creating a tertiary MCR. Alternatively, the radical function can be transferred intramolecularly to any position within the chain (also forming an MCR) or intermolecularly to another polymer strand. This article aims at providing a comprehensive overview of the up‐to‐date knowledge about the rates at which MCRs are formed, their secondary reactions as well as the consequences of their occurrence under variable reaction conditions. We explore the latest aspects of their detection (via electron spin resonance spectroscopy) as well as the characterization of the polymer structures to which they lead (via high resolution mass spectrometry). The presence of MCRs leads to the formation of branched polymers and the partial formation of polymer networks. They also limit the measurement of kinetic parameters (such as the SPR propagation rate coefficient) with conventional methods. However, their occurrence can also be used as a synthetic handle, for example, the high‐temperature preparation of macromonomers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7585–7605, 2008