bluuebunny/crossref_metadata_2025 huggingface dataset:
Silicon alleviates the toxicity of cadmium and zinc for maize (Zea mays L.) grown on a contaminated soil
Authors: Patrícia Vieira da Cunha Karina , Williams Araújo do Nascimento Clístenes , José da Silva Airon
Published: October 2008

Although silicon (Si) is not an essential element, it presents a close relationship with the alleviation of heavy‐metal toxicity to plants. This work was carried out to evaluate the effects of Si application to soil on the amelioration of metal stress to maize grown on a contaminated soil amended with Si (0, 50, 100, 150, and 200 mg kg–1) as calcium silicate (CaSiO3). Additionally, the cadmium (Cd) and zinc (Zn) bioavailability as well as their distribution into soil fractions was also studied. The results showed that adding Si to a Cd‐ and Zn‐contaminated soil effectively diminished the metal stress and resulted in biomass increase in comparison to metal‐contaminated soil not treated with Si. This relied on Cd and Zn immobilization in soil rather than on the increase of soil pH driven by calcium silicate application. Silicon altered the Cd and Zn distribution in soil fractions, decreasing the most bioavailable pools and increasing the allocation of metals into more stable fractions such as organic matter and crystalline iron oxides.
Determination of dithiothreitol in complex protein mixtures by HPLC–MS
Authors: Cindrić Mario , Čepo Tina , Marinc Sabina , Paškvan Ivan , Mijić Ivana , Bindila Laura , Peter‐Katalinić Jasna
Published: October 2008

Dithiothreitol (DTT) and other reducing agents are typically used in refolding processes of recombinant human proteins during their purification from inclusion bodies. Due to its toxicity, it is essential to monitor the clearance of DTT throughout the analytical flow from the refolding phase to the final formulated product. Here we report a direct, simple, and fast liquid chromatography method using UV and tandem mass spectrometry (MS/MS) detection for DTT evaluation in complex protein mixtures. In aqueous solution DTT exists as an equilibrium mixture of the oxidized and the reduced form (H2DTT → DTTox) and the quantitation tools should therefore be applicable to both forms in a single step or in multiple steps. Oxidation of DTT with aqueous copper(II) nitrate trihydrate solution was introduced to determine a single oxidized compound, i. e. DTTox. Proteins and other components of high molecular masses were separated from DTTox by ultrafiltration. Consequently, efficient separation of the DTTox from other flow‐through mixture components (sugars, polymers, salts, protein stabilizers) was achieved on an Atlantis dC18 column. After chromatographic separation, DTTox was selectively identified by UV absorbance at 285 nm or by selected reaction monitoring, measuring signal transition between m/z 151 → 105. The method was validated in terms of specificity, accuracy, precision, linearity, and limit of quantification and detection. A reversed‐phase HPLC separation method with atmospheric pressure chemical ionization and MS/MS detection in negative ion mode is highlighted as a viable alternative to currently existing quantitation methods involving DTT derivatization and HPLC fluorescence detection. The described approach offers simple, straightforward, selective, and high‐throughput DTT quantitation in protein mixtures.
Headspace single drop and hollow fiber liquid phase microextractions for HPLC determination of phenols
Authors: Wu Yunli , Hu Bin , Hou Yanli
Published: October 2008

Two methods based on headspace single drop microextraction (HS‐SDME) and headspace hollow fiber liquid phase microextraction (HS‐HF‐LPME) were developed and critically compared with HPLC‐UV determination of phenols (including phenol (Ph), 2‐chlorophenol (CP), 2,4‐dichlorophenol (DCP) and 2,4,6‐trichlorophenol (TCP)) in this paper. The significant parameters affecting the extraction efficiency of the target analytes in both extraction modes were studied and the optimal extraction conditions were established. Under the optimal conditions, the detection limits (S/N = 3) for Ph, CP, DCP and TCP obtained by HS‐SDME‐HPLC‐UV and HS‐HF‐LPME‐HPLC‐UV were 2.1, 0.2, 0.8,1.1 ng/mL and 4.2, 0.4, 0.4, 0.4 ng/mL with enrichment factors of 15.8, 198.9, 159.7, 194.8 and 9.2, 149.9, 301.9, 411.1, respectively. The RSDs obtained by HS‐SDME‐HPLC‐UV and HS‐HF‐LPME‐HPLC‐UV were 3.7, 4.0, 9.8, 6.7% and 6.3, 3.6, 3.1, 4.8% for Ph, CP, DCP and TCP, respectively. Both extraction modes have a comparable analytical performance, but HS‐HF‐LPME was more robust than HS‐SDME, while HS‐SDME was simpler than HS‐HF‐LPME. The two headspace microextraction modes were applied for HPLC‐UV determination of target phenols in water, honey and toner samples, and the determined values obtained by both techniques were in good agreement with each other.
Main traumatic events in Europe: PTSD in the European study of the epidemiology of mental disorders survey
Authors: Darves‐Bornoz Jean‐Michel , Alonso Jordi , de Girolamo Giovanni , Graaf Ron de , Haro Josep‐Maria , Kovess‐Masfety Viviane , Lepine Jean‐Pierre , Nachbaur Gaëlle , Negre‐Pages Laurence , Vilagut Gemma , Gasquet Isabelle
Published: October 2008

A potentially traumatic event (PTE) contributes to trauma through its frequency, conditional probability of posttraumatic stress disorder (PTSD), and experience of other PTEs. A cross‐sectional survey was conducted, enrolling 21,425 adults nationally representative of six European countries. Using the WHO‐Composite International Diagnostic Interview, 8,797 were interviewed on 28 PTEs and PTSD. Prevalence of 12‐month PTSD was 1.1%. When PTSD was present, the mean number of PTEs experienced was 3.2. In a multivariate analysis on PTEs and gender, six PTEs were found to be more traumatic, and to explain a large percentage of PTSD, as estimated by their attributable risk of PTSD: rape, undisclosed private event, having a child with serious illness, beaten by partner, stalked, beaten by caregiver.
Poisson regression for modeling count and frequency outcomes in trauma research
Authors: Gagnon David R. , Doron‐LaMarca Susan , Bell Margret , O'Farrell Timothy J. , Taft Casey T.
Published: October 2008

The authors describe how the Poisson regression method for analyzing count or frequency outcome variables can be applied in trauma studies. The outcome of interest in trauma research may represent a count of the number of incidents of behavior occurring in a given time interval, such as acts of physical aggression or substance abuse. Traditional linear regression approaches assume a normally distributed outcome variable with equal variances over the range of predictor variables, and may not be optimal for modeling count outcomes. An application of Poisson regression is presented using data from a study of intimate partner aggression among male patients in an alcohol treatment program and their female partners. Results of Poisson regression and linear regression models are compared.
Different types of exposure to the 2004 tsunami are associated with different levels of psychological distress and posttraumatic stress
Authors: Wahlström Lars , Michélsen Hans , Schulman Abbe , Backheden Magnus
Published: October 2008

The impact of traumatic exposure on psychological distress and posttraumatic stress was investigated at 14 months through self‐report in 1,505 Swedish tourists who survived the 2004 Indian Ocean Tsunami. Exposure, differentiated in single and multiple types, was associated with different levels of impaired mental health measured by General Health Questionnaire (GHQ) and Impact of Event Scale‐Revised (IES‐R). Additionally, having sole exposure to subjective life threat brought about specific psychological effects. Some demographic factors are associated with outcome on either the GHQ or the IES‐R. Identifying specific types of exposure of disaster survivors may be a way to identify individuals who could be screened for psychological ill health at a later point in time.
Creation of a community violence exposure scale: Accounting for what, who, where, and how often
Authors: Suglia Shakira Franco , Ryan Louise , Wright Rosalind J.
Published: October 2008

Previous research has used the Rasch model, a method for obtaining a continuous scale from dichotomous survey items measuring a single latent construct, to create a scale of community violence exposure. The authors build upon previous work and describe the application of a Rasch model using the continuation ratio model to create an exposure to community violence (ETV) scale including event circumstance information previously shown to modify the impact of experienced events. They compare the Rasch ETV scale to a simpler sum ETV score, and estimate the effect of ETV on child posttraumatic stress symptoms. Incorporating detailed event circumstance information that is grounded in traumatic stress theory may reduce measurement error in the assessment of children's community violence exposure.
Schweißen von Leichtmetallen verlangt modifizierte Prozesse
Authors: Dzelnitzki Dirk
Published: October 2008

Im modernen Luft‐ und Raumfahrzeugbau hat sich das Laserstrahl‐Schweißen als alternatives Fügeverfahren etabliert. Neue, leichtere Werkstoffe, die mehr und mehr zum Einsatz kommen, verlangen aber nach Prozessmodifikationen, damit das Schweißergebnis die hohen qualitative Anforderungen voll erfüllt. Beim Laserstrahl‐Schweißen von Aluminiumlegierungen lassen sich präzise und hochwertige Schweißnähte beispielsweise durch den Einsatz eines Drahtvorschub‐Systems erreichen. Um hierbei einen reibungslosen Prozessablauf zu gewährleisten, bedarf es neben der präzisen Zufuhr des Drahts auch des genauen Zusammenspiels aller Systemkomponenten.
Sub‐millimeter resolution 3D optical imaging of living tissue using laminar optical tomography
Authors: Hillman E.M.C. , Burgess S.A.
Published: October 2008

In‐vivo imaging of optical contrast in living tissues can allow measurement of functional parameters such as blood oxygenation and detection of targeted and active fluorescent contrast agents. However, optical imaging must overcome the effects of light scattering, which limit the penetration depth and can affect quantitation and sensitivity. This article focuses on a technique for high‐resolution, high‐speed depth‐resolved optical imaging of superficial living tissues called laminar optical tomography (LOT), which is capable of imaging absorbing and fluorescent contrast in living tissues to depths of 2–3 mm with 100–200 micron resolution. An overview of the advantages and challenges of in‐vivo optical imaging is followed by a review of currently available techniques for high‐resolution optical imaging of tissues. LOT is then described, including a description of the imaging system design and discussion of data analysis and image reconstruction approaches. Examples of recent applications of LOT are then provided and compared to other existing technologies.
Modification of single molecule fluorescence near metallic nanostructures
Authors: Lakowicz J.R. , Fu Yi
Published: October 2008

In recent years there has been a growing interest in the interactions of fluorophores with metallic nanostructures or nanoparticles. The spectra properties of fluorophores can be dramatically modified by near‐field interactions with the electron clouds present in metals. Near‐field interactions are those occurring within a wavelength distance of an excited fluorophore. These interactions modify the emission in ways not seen in ensemble fluorescence experiments. In this review we provide an insightful description of the photophysics of metal plasmons and near‐field interactions. Additionally, we summarize recent works on single‐molecule studies on metal‐fluorophore interactions and suggest how these effects will result in new classes of experimental procedures, novel probes, bioassays and devices.
Detecting lifetime alcohol problems in individuals referred for liver transplantation for nonalcoholic liver failure
Authors: Day Ed , Best David , Sweeting Ruth , Russell Rebecca , Webb Kerry , Georgiou George , Neuberger James
Published: October 2008

Transplantation for alcoholic liver disease is becoming increasingly common, and with adequate screening, short- to medium-term outcomes are very good. However, while conducting a prospective study of the outcome of liver transplantation in Birmingham, United Kingdom, we observed that a research diagnosis of alcohol abuse or dependence was made in a number of cases in which no reference to alcohol problems had been made by the referring agency. This article explores the characteristics of these “missed” cases and highlights key patient characteristics that might prompt a more detailed assessment of alcohol consumption. Two hundred eight individuals completed the research interview, and 80 (39%) met Diagnostic and Statistical Manual of Mental Disorders IV criteria for a lifetime diagnosis of either alcohol abuse (n = 29) or dependence (n = 51). When the initial referral details were reviewed, the possibility of alcohol problems had not been raised in 10 (12.5%) of these cases. Hepatitis C was the most common primary diagnosis in the missed cases, but there was no difference between diagnosed and missed cases in terms of demographic factors, severity of liver disease, or the number or degree of lifetime problems associated with alcohol. However, members of the missed group were more likely to have drunk alcohol in the past 6 months and in a greater volume and were more likely to have used illicit drugs such as opiates, amphetamines, hallucinogens, and cannabis. These findings point to the need to take an adequate history of lifetime alcohol problems in all patients being considered for liver transplantation. Liver Transpl 14:1609–1613, 2008. © 2008 AASLD.
Liver transplantation for hepatoblastoma
Authors: Faraj Walid , Dar Faisal , Marangoni Gabriele , Bartlett Adam , Melendez Hector Vilca , Hadzic Dino , Dhawan Anil , Mieli-Vergani Georgina , Rela Mohamed , Heaton Nigel
Published: October 2008

From October 1993 to February 2007, 25 liver transplantations were performed for hepatoblastoma. Of these 25, 18 children received cadaveric grafts, and 7 received left lateral segments from living donors. Fifteen patients were at level IV in the pretreatment extent of disease staging system for hepatoblastoma (PRETEXT IV; 11 received cadaveric grafts and 4 underwent living related liver transplantation [LRLT]) and 10 were level III (PRETEXT III; 7 received cadaveric grafts and 3 underwent LRLT). Preoperative chemotherapy was given according to the risk stratification system for children with hepatoblastoma protocols of the International Childhood Liver Tumour Strategy Group of the International Society of Paediatric Oncology (SIOPEL): SIOPEL I in the first 3 patients, SIOPEL II in 6, SIOPEL III in 10, and SIOPEL IV in 3 patients. Patient and graft survival after cadaveric transplantation was 91%, 77.6%, and 77.6%, at 1, 5, and 10 years, respectively, with no retransplantations. Patient and graft survival for children undergoing LRLT was 100%, 83.3%, and 83.3%, at 1, 5, and 10 years, respectively. All surviving children but 1 remain disease-free, with a median follow up of 6.8 years (range, 0.9–14.9). There were 5 deaths at a median of 13 months post-transplantation, secondary to tumor recurrence (4) and respiratory failure (1). Liver transplantation is an established treatment for unresectable hepatoblastoma confined to the liver following chemotherapy. LRLT is a therapeutic option given that the outcome is similar to that of resection and cadaveric transplantation. Liver Transpl 14:1614–1619, 2008. © 2008 AASLD.
Metabolic syndrome in liver transplantation: Relation to etiology and immunosuppression
Authors: Bianchi Giampaolo , Marchesini Giulio , Marzocchi Rebecca , Pinna Antonio D. , Zoli Marco
Published: October 2008

Excessive weight gain, hypertension, hyperlipidemia, and diabetes are frequently observed in patients having undergone liver transplantation (LTx). These alterations are probably multifactorial in origin, and cluster to generate a metabolic syndrome (MS), increasing the risk of cardiovascular events. We assessed the prevalence of MS (National Cholesterol Education Program-Adult Treatment Panel III criteria) in 296 LTx patients in the course of regular follow-up, at least 6 months after transplantation (median, 38 months). Several pre-LTx and post-LTx data were collected to identify the factors associated with the presence of MS. In a subset of 99 patients, insulin resistance was measured by the homeostasis model assessment. High blood pressure was present in 53% of cases, hyperlipidemia in 51%, high glucose in 37%, and enlarged waist circumference in 32%. Overall, MS (defined as 3 or more of the above features) was present in 44.5% of cases. Insulin resistance (homeostasis model assessment > 2.7) was observed in 41% of cases. Hypertension and hyperlipidemia were more frequent in subjects on cyclosporine than in tacrolimus-treated cases, whereas the type of immunosuppressive drug had no effect on the prevalence of diabetes, enlarged waist, and MS. In a logistic regression analysis, only pre-LTx body mass index (odds ratio, 1.20), body mass index increase (odds ratio, 1.18), and pre-LTx diabetes (odds ratio, 2.36) predicted MS; age, gender, etiology of liver disease, time from LTx, type of immunosuppressive drug, and previous hepatocellular carcinoma were removed from the model. Disorders related to MS are frequent in LTx patients, and are related to both pre-LTx conditions and to weight gain. Weight control is mandatory in LTx patients to prevent risk factors of premature atherosclerosis. Liver Transpl 14: 1648–1654, 2008. © 2008 AASLD.
Vasopressin decreases portal vein pressure and flow in the native liver during liver transplantation
Authors: Wagener Gebhard , Gubitosa Gina , Renz John , Kinkhabwala Milan , Brentjens Tricia , Guarrera James V. , Emond Jean , Lee Thomas H. , Landry Donald
Published: October 2008

Vasodilation due to impaired vascular tone is common in liver failure. Vasoconstrictor drugs are almost always required during the anhepatic phase of a liver transplant to maintain blood pressure unless venovenous bypass is employed. Arginine-vasopressin can be used as a vasoconstrictor instead of or in addition to norepinephrine for this purpose, but the effect of vasopressin on the portal vein pressure and flow in this setting is unknown. Portal vein pressure, portal vein blood flow, hemodynamic variables, and plasma vasopressin levels were measured in 16 patients during liver transplantation after ligation of the hepatic artery before and after a vasopressin infusion of 3.8 ± 1.1 units/hour. Measurements were performed on the native liver prior to caval clamping. After vasopressin infusion, the portal vein pressure decreased significantly from 24.0 ± 6.5 to 21.5 ± 7.4 mm Hg [mean ± standard deviation (SD), P = 0.006]. The portal vein blood flow also decreased (from 1.01 ± 0.53 to 0.76 ± 0.53 L/minute, mean ± SD, P < 0.0001), as did the portal vein blood flow to cardiac output ratio (from 0.14 ± 0.06 to 0.10 ± 0.07, mean ± SD, P < 0.0001). In conclusion, vasopressin significantly decreased portal vein pressure and flow of the native liver without decreasing cardiac output or intestinal perfusion in patients undergoing liver transplantations. Liver Transpl 14:1664–1670, 2008. © 2008 AASLD.
Institutional constraints on organizations: the case of Spanish car dealerships
Authors: Arruñada Benito , Vázquez Luis , Zanarone Giorgio
Published: October 2008

We study the effect of organizational choice and institutions on the performance of Spanish car dealerships. Using outlet‐level data from 1994, we find that vertically integrated dealerships showed substantially lower labor productivity, higher labor costs and lower profitability than franchised ones. Despite these gaps in performance, no vertically integrated outlet was separated until 1994, yet the few outlets that were eventually separated systematically improved their performance. We argue that the conversion of integrated outlets into franchised ones involved significant transaction costs, due to an institutional environment favoring permanent, highly unionized employment relations. In line with this argument, we find that the observed separations occurred in distribution networks that underwent marked reductions in worker unionization rates, following the legalization of temporary labor contracts. Copyright © 2008 John Wiley & Sons, Ltd.
Corporate governance and firm efficiency: evidence from China's publicly listed firms
Authors: Lin Chen , Ma Yue , Su Dongwei
Published: October 2008

This paper applies a two‐stage, double bootstrapping data envelope analysis approach to investigate whether and to what extent various distinctive corporate governance practices affect productive efficiency in a sample of 461 publicly listed manufacturing firms in China between 1999 and 2002. We find that firm efficiency is negatively related to state ownership while positively related to public and employee share ownership. In addition, the relationship between ownership concentration and firm efficiency is U‐shaped, indicating the presence of tunneling activities by the largest shareholder. Among three types of controlling shareholder, state exerts the most negative impact on firm efficiency, followed by state‐owned legal entities. These results provide strong evidence that political interferences have reduced firm efficiency. It shows that the proportion of outside directors and the number of board meetings are positively associated with firm efficiency, suggesting that board of directors can be an effective internal governance mechanism. Furthermore, provincial market development, a proxy for the strength of external governance mechanism, is positively related to firm efficiency. Overall, our findings illustrate that restructuring state‐owned enterprises via improvements in corporate governance has enhanced firm efficiency, but partial privatization without transfer of ownership and control from the state to the public remains a major source of inefficiency in corporate China. Copyright © 2008 John Wiley & Sons, Ltd.
Applause sign in parkinsonian disorders and Huntington's disease
Authors: Wu Laura J.C. , Sitburana Oraporn , Davidson Anthony , Jankovic Joseph
Published: October 2008

The applause sign has been previously reported to be indicative of neurodegenerative disorders, such as progressive supranuclear palsy (PSP). In order to determine the sensitivity, specificity, and positive predictive value, we tested it in patients with PSP, Parkinson's disease (PD), multiple system atrophy (MSA), corticobasal degeneration (CBD), and Huntington's disease (HD). Subjects were asked to clap three times after demonstration by the examiner. The performance was scored as follows: 3 = claps only three times; 2 = claps four times; 1 = claps 5 to 10 times; 0 = claps >10 times. The clap test was videotaped and rated. Patients with CBD, MSA, and PSP showed significant differences in clap scores compared with normal controls. The test differentiated patients with CBD from those with PD (P < 0.005) and HD (P < 0.005), but failed to discriminate patients with PSP from other parkinsonian groups. The specificity of the applause sign is 100% in distinguishing parkinsonian patients from normal subjects with the highest sensitivity in CBD patients. We concluded that the applause sign is highly specific for parkinsonian disorders but it is not a specific sign for PSP; it appears to be most sensitive for CBD. © 2008 Movement Disorder Society
Excessive postural sway and the risk of falls at different stages of Parkinson's disease
Authors: Frenklach Anna , Louie Stephanie , Koop Mandy Miller , Bronte‐Stewart Helen
Published: October 2008

Excessive postural sway may result in falls in Parkinson's disease (PD). We measured postural sway using the sensory organization test (SOT) of dynamic posturography in static (platform still) and dynamic (sway referenced platform) conditions with normal, no and inappropriate visual feedback in 102 subjects with PD, off medication. Twenty‐five healthy subjects were used as age‐matched controls. Eighteen very early stage PD subjects had never used dopaminergic medication. Postural sway was normal in those subjects in all conditions, but was abnormal in subjects with more advanced symptoms (UPDRS III > 20, P < 0.01). Postural sway increased with disease severity in all conditions except static, eyes closed (P < 0.0001). We developed the SOT Fall Severity Scale (SOTFSS) from the number of times postural sway was so large that the subject had to take a step (registered as a “fall”) and showed that falls mainly occurred in dynamic conditions, and were correlated with disease severity (P < 0.0001). In dynamic conditions the SOTFSS was correlated with the retropulsion score from the UPDRS III (N = 102, P < 0.0001) and with the subjects' self‐reported fall frequency from the UPDRS II (N = 62, SOT5: P = 0.0419, SOT6: P = 0.0034). © 2008 Movement Disorder Society
All‐author vs. first‐author co‐citation analysis of the Information Science field using Scopus
Authors: Zhao Dangzhi , Strotmann Andreas
Published: October 2008

Although many studies on the various ways of allocating credit among co‐authors have brought into general recognition that different citation counting methods can result in quite different author rankings, studies on different author co‐citation counting methods are still largely missing. This paper examines whether different co‐citation counting methods produce different results in author co‐citation analysis studies of the intellectual structure of research fields, and if so, in what ways they differ. Our results indicate that, with respect to the major specialties and how they relate to each other, the intellectual structures of the Information Science field identified through author co‐citation analyses based on different co‐citation counting methods are largely equivalent, but when it comes to detailed structure, results differ in a number of ways. In particular, classic first‐author co‐citation analysis appears to better represent the theoretical and methodological aspects of the field whereas all‐author co‐citation analysis favors more recent empirical studies, and picks out some tightly collaborative research groups or projects. We experiment with using meaningful diagonal values in a co‐citation matrix rather than using statistically generated values, and observe favorable results. We also employ a new visualization technique for reporting the results of a classic author co‐citation analysis, using a bipartite graph that represents all the information in the factor matrix of specialties and author loadings as author and factor vertices connected by edges with loadings as similarity‐measure line values, laid out algorithmically in two dimensions.
Verification of information behavioral grammar: Role of searchers
Authors: Miwa Makiko
Published: October 2008

This paper reports on a verification study of the information behavioral grammar (IBG) model initially developed in 2000. We used a modified critical incident technique to identify how social science faculty members' information‐seeking processes are engaged differently for their differing role tasks. A semistructured interview was conducted on the recently experienced information‐seeking processes of researchers, teachers, and personal/family decision makers. As a result, 31 information‐seeking processes (nine on research, six on teaching, and 16 for personal/family decision making) were identified. Contents of recorded interviews were analyzed for associations among behavioral, cognitive, affective, social and environmental aspects using the constant‐comparative method. The characteristics of information‐seeking processes for each role were identified and compared with the IBG model. Results indicate that the IBG model fits the patterns identified for social scientists' information‐seeking processes for research and teaching. However, we could not obtain reliable data to verify the applicability of the IBG model to their information‐seeking processes for personal/family decision making, mainly because these processes were deeply embedded in their everyday life activities and, in most cases, were taken for granted, which made difficult recall of the exact sequence of actions with associated cognitive, affective, social and environmental situations.
An MR guidewire based on micropultruded fiber‐reinforced material
Authors: Krueger Sascha , Schmitz Sebastian , Weiss Steffen , Wirtz Daniel , Linssen Marita , Schade Heinz , Kraemer Nils , Spuentrup Elmar , Krombach Gabriele , Buecker Arno
Published: October 2008

A novel fiber‐reinforced material for the realization of MR guidewires, made using a newly‐developed production process, is presented. The MR‐safe artificial material provides a high stiffness and torque and allows the production, in a large range of sizes, of nonmetallic MR guidewires with similar mechanical properties as conventional metallic guidewires. Based on this material, a passively visualized MR guidewire has been developed, and was found to conform to existing standards on mechanical stability. Handling and steerability were evaluated in animal studies and were found to be comparable with conventional metallic guidewires. X‐ray visibility is provided by a BaSO4‐ and tungsten‐doped jacket. A hydrophilic coating improves sliding properties and hemocompatibility. Magn Reson Med 60:1190–1196, 2008. © 2008 Wiley‐Liss, Inc.
Gadolinium‐modulated 19F signals from perfluorocarbon nanoparticles as a new strategy for molecular imaging
Authors: Neubauer Anne M. , Myerson Jacob , Caruthers Shelton D. , Hockett Franklin D. , Winter Patrick M. , Chen Junjie , Gaffney Patrick J. , Robertson J. David , Lanza Gregory M. , Wickline Samuel A.
Published: October 2008

Recent advances in the design of fluorinated nanoparticles for molecular magnetic resonance imaging (MRI) have enabled specific detection of 19F nuclei, providing unique and quantifiable spectral signatures. However, a pressing need for signal enhancement exists because the total 19F in imaging voxels is often limited. By directly incorporating a relaxation agent, gadolinium (Gd), into the lipid monolayer that surrounds the perfluorocarbon (PFC), a marked augmentation of the 19F signal from 200‐nm nanoparticles was achieved. This design increases the magnetic relaxation rate of the 19F nuclei fourfold at 1.5 T and effects a 125% increase in signal—an effect that is maintained when they are targeted to human plasma clots. By varying the surface concentration of Gd, the relaxation effect can be quantitatively modulated to tailor particle properties. This novel strategy dramatically improves the sensitivity and range of 19F MRI/MRS and forms the basis for designing contrast agents capable of sensing their surface chemistry. Magn Reson Med 60:1066–1072, 2008. © 2008 Wiley‐Liss, Inc.
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

We 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

Black 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

The 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

Quantification 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

Despite 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

Obwohl 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

Atmen – 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

Husten 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

Rauchen 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

The 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

Nanocomposites 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

Poly(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

Cadmium 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

Despite 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.