bluuebunny/crossref_metadata_2025 huggingface dataset:
The kinetics of force‐induced cell reorganization depend on microtubules and actin
Authors: Goldyn Alexandra M. , Kaiser Peter , Spatz Joachim P. , Ballestrem Christoph , Kemkemer Ralf
Published: February 2010

The cytoskeleton is an important factor in the functional and structural adaption of cells to mechanical forces. In this study we investigated the impact of microtubules and the acto‐myosin machinery on the kinetics of force‐induced reorientation of NIH3T3 fibroblasts. These cells were subjected to uniaxial stretching forces that are known to induce cellular reorientation perpendicular to the stretch direction. We found that disruption of filamentous actin using cytochalasin D and latrunculin B as well as an induction of a massive unpolarized actin polymerization by jasplakinolide, inhibited the stretch‐induced reorientation. Similarly, blocking of myosin II activity abolished the stretch‐induced reorientation of cells but, interestingly, increased their motility under stretching conditions in comparison to myosin‐inhibited nonstretched cells. Investigating the contribution of microtubules to the cellular reorientation, we found that, although not playing a significant role in reorientation itself, microtubule stability had a significant impact on the kinetics of this event. Overall, we conclude that acto‐myosin, together with microtubules, regulate the kinetics of force‐induced cell reorientation. © 2010 Wiley‐Liss, Inc.
The molecular basis of frictional loads in the in vitro motility assay with applications to the study of the loaded mechanochemistry of molecular motors
Authors: Greenberg Michael J. , Moore Jeffrey R.
Published: February 2010

Molecular motors convert chemical energy into mechanical movement, generating forces necessary to accomplish an array of cellular functions. Since molecular motors generate force, they typically work under loaded conditions where the motor mechanochemistry is altered by the presence of a load. Several biophysical techniques have been developed to study the loaded behavior and force generating capabilities of molecular motors yet most of these techniques require specialized equipment. The frictional loading assay is a modification to the in vitro motility assay that can be performed on a standard epifluorescence microscope, permitting the high‐throughput measurement of the loaded mechanochemistry of molecular motors. Here, we describe a model for the molecular basis of the frictional loading assay by modeling the load as a series of either elastic or viscoelastic elements. The model, which calculates the frictional loads imposed by different binding proteins, permits the measurement of isotonic kinetics, force‐velocity relationships, and power curves in the motility assay. We show computationally and experimentally that the frictional load imposed by alpha‐actinin, the most widely employed actin binding protein in frictional loading experiments, behaves as a viscoelastic rather than purely elastic load. As a test of the model, we examined the frictional loading behavior of rabbit skeletal muscle myosin under normal and fatigue‐like conditions using alpha‐actinin as a load. We found that, consistent with fiber studies, fatigue‐like conditions cause reductions in myosin isometric force, unloaded sliding velocity, maximal power output, and shift the load at which peak power output occurs. © 2010 Wiley‐Liss, Inc.
Identification of focal adhesion kinase (FAK) and phosphatidylinositol 3‐kinase (PI3‐kinase) as Par3 partners by proteomic analysis
Authors: Itoh Norimichi , Nakayama Masanori , Nishimura Takashi , Fujisue Shin , Nishioka Tomoki , Watanabe Takashi , Kaibuchi Kozo
Published: February 2010

Partition defective 3 (Par3) is involved in a variety of polarity events including establishment of apico‐basal polarity of epithelial cell, axon/dendrite specification of neurons and directional migration of cells with front‐rear polarity. Par3 is thought to regulate cell polarity as a scaffold protein by interacting with various partner proteins such as Par6, aPKC, Tiam1/2 and Numb. However, the mode of actions of Par3 in polarized migration remains largely unknown. To explore Par3 functions, we screened Par3‐interacting proteins by combining Par3 affinity column chromatography and shotgun analysis using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). We obtained about two hundred Par3‐interacting proteins from the rat brain cytosol fraction. Among them, we focused on FAK and PI3‐kinase, as both of them participate in directional cell migration. FAK associated with the PDZ domain and the coiled‐coil region of Par3 and p110 of PI3‐kinase associated with the coiled‐coil region of Par3. Par3 was partially colocalized with FAK in spreading cells. Depletion of Par3 by RNA interference inhibited adhesion‐induced activation of FAK and PI3‐kinase, and RNA interference‐resistant Par3 restored the inhibitory effects. In addition, Par3 was required for the adhesion‐induced cell spreading as well as for directional cell migration toward collagen. These results suggest that Par3 directly interacts with FAK and PI3‐kinase, enhancing their activities for polarized cell migration. © 2010 Wiley‐Liss, Inc.
How do social firms contribute to recovery from mental illness? A qualitative study
Authors: Svanberg Jenny , Gumley Andrew , Wilson Alistair
Published: February 2010

Background: A definition of recovery drawn from qualitative literature and the ‘consumer/survivor’ movement suggests that recovery should be seen as a way of developing satisfaction and purpose in life, whether or not symptoms of mental illness are present. A qualitative review suggested that meaningful activity may facilitate recovery by providing a sense of purpose in life. Social firms may be well placed to offer this activity due to their ethos of empowerment, their community integration and their similarity to ‘recovery‐oriented services’.

Aims: The aim of this study was to explore experiences of recovery from mental illness in the context of two emerging social firms.

Method: A social constructionist version of grounded theory was used to develop a model of recovery through participation in the emerging social firms. Multiple coding, triangulation and respondent validation were used to increase the rigour of study findings.

Findings: A model of recovery in the context of the emerging social firms was constructed. This was influenced by characteristics such as a flexible structure, a meaningful and diverse activity, an accepting social group and an inclusive leadership.

Conclusion: Social firms may provide an important model for ‘recovery‐oriented services’. Clinical, research and policy implications of findings are discussed. Copyright © 2010 John Wiley & Sons, Ltd.

Key Practitioner Message:

Social firms are a form of enterprise that employs people who are disadvantaged in the labour market by their disability.

Social firms promote a model of community integration and empowerment for their employees.

We found that individuals recovering from a mental illness experience social firms as providing a flexible environment which promotes feelings of belonging, success, competence and individuality.

We interpret these findings as social firms providing secure base for recovery.
Fear of recurrence: a case report of a woman breast cancer survivor with GAD treated successfully by CBT
Authors: Montel Sébastien
Published: February 2010

General anxiety disorder (GAD) characterized by persistent, excessive and unrealistic worry about everyday things can affect everybody, including cancer patient survivor.

In this paper, we present a case report of a breast cancer survivor with GAD treated by cognitive–behavioural therapy (CBT), who was excessively worried about recurrence of the disease 2 years after the end of any treatment.

Cognitive reframing, associated to behavioural exposure and relaxation, were used in order to treat this woman. We describe precisely how the therapy was conducted.

Results showed a substantial improvement of the fear of recurrence which ‘naturally’ extended to other stressful situations not worked during the therapy.

Actually, these results are encouraging since it showed that CBT can be efficient in complicated situation involving survivor of a serious disease like cancer who additionally suffers from an anxiety disorder. It also underlines how it is important to be concerned by the distress of cancer survivors. Copyright © 2010 John Wiley & Sons, Ltd.

Key Practitioner Message:

Fear of recurrence is a real problem for cancer's survivors.

Cancer's survivors affected by psychic disorders need a special psychological assistance.

CBT prove to be efficient with these patients.
Metacognitions about smoking: a preliminary investigation
Authors: Nikčević Ana V. , Spada Marcantonio M.
Published: February 2010

Preliminary research has indicated that metacognitions are involved in smoking. In the present study, we aimed to investigate whether specific facets of metacognition play a role in explaining smoking initiation and perseveration. Twelve individuals, self‐identified as regular smokers and scoring a positive value on the Fagerström Test of Nicotine Dependence, were assessed using a semi‐structured interview to investigate the following: (1) whether they held positive and/or negative metacognitive beliefs about smoking; (2) what their main goal in smoking was, and how they knew if they had achieved their goal; (3) how they directed their focus of attention when smoking; and (4) what they perceived the advantages and disadvantages of these attentional strategies to be. Results indicated that participants endorsed both positive and negative metacognitive beliefs about smoking and that the goal of smoking was to regulate negative emotion and/or to enhance cognitive functioning. Participants reported that they relied either on an internal signal, such as improvement in the emotional/cognitive state, or on a physical sign, in the form of a finished cigarette, to determine if they had achieved their goal. During an episode of smoking, half of the participants reported focusing their attention internally on thoughts and feelings or the sensations of smoking. The remainder of participants reported either an exclusively external focus of attention (e.g., the environment) or a varied focus of attention. Most participants were able to identify advantages to their attentional strategies, whereas two reported perceived disadvantages. The implications of the findings are discussed. Copyright © 2010 John Wiley & Sons, Ltd.

Key Practitioner Message

• Cognitive‐attentional profiling that may aid assessment and conceptualisation of smoking behaviour.
Sustainable development: the role of network communication
Authors: Nielsen Anne Ellerup , Thomsen Christa
Published: February 2010

Research within the field of sustainable development has documented a number of network initiatives taken by corporations in order to manage financial, social, and environmental pressures. So far, the focus of the research has been to address the concerns raised by a number of external stakeholders. As such, research attention has been paid to the reactive corporate response rather than to the proactive communication of the sustainability message with the purpose of developing and driving corporate social responsibility (CSR) and sustainability. Only recently, a few papers have emerged on the issue. The purpose of this paper is to contribute to the field by proposing a theoretical analysis of the organizational and communicative bases of CSR and sustainability networks. Resource dependence theory and social network theory are used to form the theoretical framework set up for understanding how governments build relations with local networks, including corporations. The framework is tested on an example from Denmark. Copyright © 2010 John Wiley & Sons, Ltd and ERP Environment.
New biological investigations on 3‐bromophenyl 6‐acetoxymethyl‐2‐oxo‐2H‐1‐benzopyran‐3‐carboxylate as anti‐angiogenic agent
Authors: Hemmer Marc , Kempen Isabelle , de Tullio Pascal , Frankenne Françis , Lambert Vincent , Blacher Silvia , Bueb Jean‐Luc , Foidart Jean‐Michel , Noël Agnès , Tschirhart Eric , Pirotte Bernard
Published: February 2010

The development of blood vessels inside tumors is required to provide the nutrients and oxygen needed for tumor growth and to allow the spread of cancer cells at a distance to form metastasis. Angiogenesis is also implicated in ocular diseases like age‐related macular degeneration. The present work describes the potential anti‐angiogenic properties of a coumarinic derivative, 3‐bromophenyl 6‐acetoxymethyl‐2‐oxo‐2H‐1‐benzopyran‐3‐carboxylate (IK9), previously described as a potent inhibitor of HT 1080 fibrosarcoma cell invasion in vitro and tumor growth in vivo. In vivo, ex vivo, and in vitro models were used to delineate the anti‐angiogenic properties of IK9. The anti‐angiogenic effect of IK9 was demonstrated in vivo in a choroidal neovascularization mice model and additionally ex vivo in a rat aortic ring assay where it was more active than the known matrix metalloproteinase inhibitor Ro 28‐2653. IK9 did not affect apoptosis, proliferation, or endothelial cell invasiveness in vitro. These findings suggest a complex mechanism of action of the compound via direct or indirect effects on endothelial cell properties. This study identifies IK9 as a new potent inhibitor of angiogenesis and suggests its potential use as a therapeutic agent. Drug Dev Res 71, 2010. © 2010 Wiley‐Liss, Inc.
A validated stability‐indicating gas chromatography method for determination of divalproex sodium impurities in pharmaceutical preparation
Authors: Subasranjan Acharya , Suresh Pulluru , Srinivasulu C. , Hemant Raoutray
Published: February 2010

A stability‐indicating gas chromatography (GC) method has been developed and validated for the quantitative determination of divalproex sodium impurities in pharmaceutical preparation. A technique has been developed whereby the peak purity of a compound with poor UV detection can be determined using a gas chromatograph coupled with a mass spectrometer. The drug products were subjected to hydrolysis, oxidation, photolysis, and heat to apply stress conditions. The stability‐indicating nature of the method has been proven by establishing peak purity of all stressed samples. The chromatographic separation was performed on a fused silica capillary (Quadrex‐FFAP, 30 meter, 0.32 mm and 1 µm film thickness) column. The method validation results indicate that the method is specific, accurate, linear, reproducible, rugged, and robust. The effectiveness of the technique was demonstrated with stability sample analysis of divalproex sodium in its pharmaceutical preparation. Copyright © 2010 John Wiley & Sons, Ltd.
Spectrophotometric and spectrodensitometric determination of triamterene and xipamide in pure form and in pharmaceutical formulation
Authors: Wagieh Nour E. , Abbas Samah S. , Abdelkawy M. , Abdelrahman Maha M.
Published: February 2010

Sensitive and validated UV‐spectrophotometric, chemometric and TLC‐densitometric methods were developed for determination of triamterene (TRM) and xipamide (XIP) in their binary mixture, formulated for use as a diuretic, without previous separation. Method A is the isoabsorptive point spectrophotometry, in which TRM concentration alone can be determined at its λmax while XIP concentration can be determined by measuring total concentration of TRM and XIP at their isoabsorptive point followed by subtraction. Method B is the ratio subtraction spectrophotometry, where XIP can be determined by dividing the spectrum of the mixture by the spectrum of TRM (as a divisor) followed by subtracting the constant absorbance value of the plateau region, then finally multiplying the produced spectrum by the spectrum of the divisor, while TRM concentration can be determined at its λmax. Method C is a chemometric‐assisted spectrophotometry where classical least squares, principal component regression, and partial least squares were applied. Method D is a TLC‐densitometry; this method depends on quantitative densitometric separation of thin layer chromatogram of TRM and XIP using silica gel plates at 254 nm. The proposed methods were successfully applied for the analysis of TRM and XIP in their pharmaceutical formulation and the results were statistically compared with the established HPLC method. Copyright © 2010 John Wiley & Sons, Ltd.
Influence of the semi‐permeable membrane on the performance of dynamic field gradient focusing
Authors: Burke Jeffrey M. , Ivory Cornelius F.
Published: February 2010

This paper is part of our continued effort to understand the underlying principles of dynamic field gradient focusing. In this investigation, we examined three problems associated with the use of a semi‐permeable membrane. First, the influence of steric and ionic exclusion of current carrying ions through the membrane was examined. It was found that resistance to the transport of ions across the membrane resulted in a shallowing of the electric field profile and an increase in the size of the defocusing zone, which is where the slope of the electric field is reversed so that it disperses rather than concentrates solutes. These problems could be reduced by using a membrane with large pores relative to the size of the buffering ions and completely void of fixed charges. Next, a numerical simulation was used to investigate concentration polarization of protein onto the surface of the membrane. Due to the presence of a transverse electric field, species were pulled toward the membrane. If the membrane is restrictive to those species, a concentrated, polarized layer will form on the surface. The simulation showed that by decreasing the channel to a depth of 20 μm, the concentrated region next to the membrane could be reduced. Finally, it was found that changes in column volume due to loss of membrane structural integrity could be mitigated by including a porous ceramic support. The variation in peak elution times was decreased from greater than 20% to less than 3%.
Protein adsorption‐dependent electro‐kinetic pore flow: Modeling of ion‐exchange electrochromatography with an oscillatory transverse electric field
Authors: Yuan Wei , Zhao Yan‐Pu , Zhang Qiang , Sun Yan
Published: February 2010

Electro‐kinetic acceleration of protein mass transfer was studied by dynamic chromatographic experiments and computer simulations on IEC with an oscillatory transverse electric field (EF) perpendicular to the mobile‐phase flow (pIEEC). The breakthrough behavior of BSA was investigated at different electric current densities. A two‐dimensional mathematical model has been established to describe the electro‐kinetic convection‐diffusion behavior of protein adsorption in a single adsorbent particle. The equation was coupled with the axial dispersion model to simulate the dynamic adsorption process in the pIEEC. The model parameters were determined by independent experiments or calculations. It was found that protein adsorption led to an exponential decrease of intraparticle electro‐kinetic flow with increasing protein adsorption. Taking this effect into consideration, the model calculations could well describe dynamic breakthrough curves. Moreover, protein distribution in adsorbents was observed to present excursion along the periodical oscillatory EF direction. At the beginning of pIEEC, intraparticle convection caused by the EF contributed more to the enhancement of dynamic binding capacity. Finally, it was confirmed that both the EOF and electrophoresis contributed to the acceleration of mass transfer.
Numerical studies of electrokinetic control of DNA concentration in a closed‐end microchannel
Authors: Daghighi Yasaman , Li Dongqing
Published: February 2010

A major challenge in lab‐on‐a‐chip devices is how to concentrate sample molecules from a dilute solution, which is critical to the effectiveness and the detection limit of on‐chip bio‐chemical reactions. A numerical study of sample concentration control by electrokinetic microfluidic means in a closed‐end microchannel is presented in this paper. The present method provides a simple and efficient way of concentration control by using electrokinetic trapping of a charged species of interest, controlling liquid flow and separating different sample molecules in the microchannel. The electrokinetic‐concentration process and the controlled transport of the sample molecules are numerically studied. In this system, in addition to the electroosmotic flow and the electrophoresis, the closed‐end of the chamber causes velocity variation at both ends of the channel and induces a pressure gradient and the associated fluid movement in the channel. The combined effects determine the final concentration field of the sample molecules. The influences of a number of parameters such as the channel dimensions, electrode size and the applied electric field are investigated.
High‐throughput log P determination by MEEKC coupled with UV and MS detections
Authors: Henchoz Yveline , Romand Stéphanie , Schappler Julie , Rudaz Serge , Veuthey Jean‐Luc , Carrupt Pierre‐Alain
Published: February 2010

A high‐throughput screening method using MEEKC was developed for the determination of 1‐octanol‐water partition coefficients (log Poct). Two approaches were carried out to decrease determination times to about 20 min per compound: (i) a dynamically coated capillary was used to increase the EOF at low pH, allowing the measurement of log Poct of acidic compounds and (ii) a short‐end injection was performed to reduce the capillary effective length. The analytical conditions were optimized to determine the lipophilicity of neutral, basic, and acidic compounds with log Poct ranging from 0 to 5. The developed method was first applied to a well‐balanced set of 35 reference compounds, and second to a set of 21 acidic and 29 basic pharmaceutical compounds. Finally, determinations were achieved with MS detection, allowing a 20‐fold throughput increase thanks to sample pooling. An atmospheric pressure photoionization source was selected to advantageously replace ESI as it was less affected by the non‐volatile BGE additives used in MEEKC.
Optimization of charged species separation by autogenous electric field‐flow fractionation in nano‐scale channels
Authors: Griffiths Stewart K. , Nilson Robert H.
Published: February 2010

Numerical methods are employed to examine the resolution and optimization of a relatively new technique for charged species separation that is based on flow along nano‐scale channels having an electric double‐layer thickness comparable to the channel size. In such channels, the electric field inherent to the double‐layer produces transverse species distributions that depend on the species charge. Flow along the channel thus yields mean axial species speeds that also depend on the species charge, enabling species separation and identification. Building on earlier work describing retention and plate heights, here we characterize this new type of field‐flow fractionation via the classic metric of resolution. Sample results are presented and discussed for a wide range of conditions for both pressure‐driven and electroosmotic flows. Optimum design and operating conditions are also examined. We find that resolution is maximized for optimum values of the ζ potential and Debye layer thickness and that these optima depend strongly on the species charge or range of charges of interest. Under optimum conditions, acceptable resolution can be obtained over a wide range of species charges for pressure‐driven flows. This separable range of charges is much smaller for electroosmotic flows. Finally, sample calculations are presented showing that all species in the range of charge between −8 to 10 can be separated simultaneously with resolutions above unity, and this is possible in less than 6 s under optimum conditions that are readily achievable.
Analyte transport in liquid junction nano‐electrospray interface between capillary electrophoresis and mass spectrometry
Authors: Klepárník Karel , Otevřel Marek
Published: February 2010

The optimization of working parameters controlling the transfer of an analyte from the separation into the spray capillary at the liquid junction interface is a complex problem. The numerical models of hydrodynamic flow, electric field strength and the consequential mass transfer provide a valuable insight into the function of the miniaturized device. The results revealed that the most important parameter is the electric field strength inside the gap between the separation and spray capillaries. In a strong electric field, the analyte leaving the separation capillary is immediately transferred into the spray capillary at its maximum concentration. Although the losses of analyte outside the interface are dominant in this case, the sprayed concentration determines the detection sensitivity. Since only a small amount of the sprayed material enters mass spectrometer, the losses at the interface do not influence the sensitivity. At low electric field strength the total amount of analytes is transferred into the spray capillary. In this case, however, the analytes enter the capillary slowly and, as a result, are significantly diluted. The electric field strength, pressure and dimensions determine the mass transfer in the interface and must be considered when the optimum conditions of an analysis are chosen. Several fold improvement in sensitivity and efficiency of the method can be expected when working under the optimum conditions.
Electrochromatographic retention of peptides on strong cation‐exchange stationary phases
Authors: Nischang Ivo , Höltzel Alexandra , Tallarek Ulrich
Published: February 2010

We analyze the systematic and substantial electrical field‐dependence of electrochromatographic retention for four counterionic peptides ([Met5]enkephalin, oxytocin, [Arg8]vasopressin, and luteinizing hormone releasing hormone (LHRH) ) on a strong cation‐exchange (SCX) stationary phase. Our experiments show that retention behavior in the studied system depends on the charge‐selectivity of the stationary phase particles, the applied voltage, and the peptides' net charge. Retention factors of twice positively charged peptides ([Arg8]vasopressin and LHRH at pH 2.7) decrease with increasing applied voltage, whereas lower charged peptides (oxytocin and [Met5]enkephalin at pH 2.7, [Arg8]vasopressin and LHRH at pH 7.0) show a concomitant increase in their retention factors. The observed behavior is explained on the basis of electrical field‐induced concentration polarization (CP) that develops around the SCX particles of the packing. The intraparticle concentration of charged species (buffer ions, peptides) increases with increasing applied voltage due to diffusive backflux from the enriched CP zone associated with each SCX particle. For twice charged and on the SCX phase strongly retained peptides the local increase in mobile phase ionic strength reduces the electrostatic interactions with the stationary phase, which explains the decrease of retention factors with increasing applied voltage and CP intensity. Lower charged and weaker retained peptides experience a much stronger relative intraparticle enrichment than the twice‐charged peptides, which results in a net increase of retention factors with increasing applied voltage. The CP‐related contribution to electrochromatographic retention of peptides on the SCX stationary phase is modulated by the applied voltage, the mobile phase ionic strength, and the peptides' net charge and could be used for selectivity tuning in difficult separations.
Characterization of nanoparticles by capillary electromigration separation techniques
Authors: Pyell Ute
Published: February 2010

Considering the large number of papers presented in the last years in the field of CE and plate gel electrophoresis (PGE) of nanoparticles and nanoparticle−biomolecule conjugates, this review article gives an overview on the application of capillary electromigration separation techniques for the separation of nanoparticles and nanoparticle−biomolecule conjugates according to differences in size and/or ζ potential and for the determination of several physicochemical parameters characterizing a population of nanoparticles. A brief introduction is given into the theoretical background of the size‐selective electrophoretic separation of nanospheres in free‐solution and sieving media including involvement of interparticle interactions. Some aspects of colloidal system stability are discussed. Applications of capillary electromigration techniques in the field of size‐selective and/or surface charge density‐selective separation of nanoparticles and nanoparticle−biomolecule conjugates are described, including free‐solution CE, CGE, IEF, and ITP, complemented by an overview on the application of (semipreparative) PGE in the field of nanotechnology and nanobiotechnology. The review also includes actual developments regarding the coupling of capillary electromigration techniques to (wavelength‐resolved) LIF and other selective detection methods and studies concerning individual‐particle CE.
Development of a membrane‐less dynamic field gradient focusing device for the separation of low‐molecular‐weight molecules
Authors: Burke Jeffrey M. , Smith Colin D. , Ivory Cornelius F.
Published: February 2010

Dynamic field gradient focusing uses an electric field gradient generated by controlling the voltage profile of an electrode array to separate and concentrate charged analytes according to their individual electrophoretic mobilities. This study describes a new instrument in which the electrodes have been placed within the separation channel. The major challenge faced with this device is that when applied voltages to the electrodes are larger than the redox potential of water, electrolysis will occur, producing hydrogen ions (H+) plus oxygen gas on the anodes and hydroxide (OH–) plus hydrogen gas on the cathodes. The resulting gas bubbles and pH excursions can cause problems with system performance and reproducibility. An on‐column, degassing system that can remove gas bubbles “on‐the‐fly” is described. In addition, the use of a high capacity, low‐conductivity buffer to address the problem of the pH shift that occurs due to the production of H+ on the anodes is illustrated. Finally, the successful separation of three, low‐molecular‐weight dyes (amaranth, bromophenol blue and methyl red) is described.
Investigation of the stereodynamics of molecules and catalyzed reactions by CE
Authors: Trapp Oliver
Published: February 2010

The investigation of the molecular dynamics of stereoisomers and the study of the kinetics of reactions, in particular of catalyzed reactions, is of fundamental interest in chemistry, biochemistry, and medicine. Understanding how to control the transition state of a reaction allows for a directed design of new catalysts and benign processes. The integration of reactions and capillary or microchip‐based electrophoretic separations is highly attractive to perform on‐column derivatizations or enzymatic on‐column digests of peptides and proteins for further characterization. The present review article focuses on the recent advances to study the stereodynamics of molecules and reaction kinetics of catalyzed processes by means of CE. Models and algorithms to evaluate interconversion profiles obtained by electrophoretic separation techniques are discussed with respect to the challenging demands of high separation efficiencies typical for electrophoretic techniques. Models used for evaluation are based on iterative computer simulation algorithms using the theoretical plate model or stochastic model of chromatography, empirical calculation methods, derived from equations used in chemical engineering, namely Damköhler analysis, and direct access with the approximation function and more recently with the unified equation, which can be applied to all kinds of first‐order reactions taking place during a chromatographic or a electrophoretic separation. Furthermore, areas of applications are presented and discussed to give a guideline for using dynamic CE and on‐column reaction electrophoresis to study kinetics of reactions and dynamic processes.
Dynamic computer simulations of electrophoresis: A versatile research and teaching tool
Authors: Thormann Wolfgang , Breadmore Michael C. , Caslavska Jitka , Mosher Richard A.
Published: February 2010

Software is available, which simulates all basic electrophoretic systems, including moving boundary electrophoresis, zone electrophoresis, ITP, IEF and EKC, and their combinations under almost exactly the same conditions used in the laboratory. These dynamic models are based upon equations derived from the transport concepts such as electromigration, diffusion, electroosmosis and imposed hydrodynamic buffer flow that are applied to user‐specified initial distributions of analytes and electrolytes. They are able to predict the evolution of electrolyte systems together with associated properties such as pH and conductivity profiles and are as such the most versatile tool to explore the fundamentals of electrokinetic separations and analyses. In addition to revealing the detailed mechanisms of fundamental phenomena that occur in electrophoretic separations, dynamic simulations are useful for educational purposes. This review includes a list of current high‐resolution simulators, information on how a simulation is performed, simulation examples for zone electrophoresis, ITP, IEF and EKC and a comprehensive discussion of the applications and achievements.
A new electrophoretic focusing principle: Focusing of nonamphoteric weak ionogenic analytes using inverse electromigration dispersion profiles
Authors: Gebauer Petr , Malá Zdena , Boček Petr
Published: February 2010

This contribution introduces a new separation principle in CE which offers focusing of weak nonamphoteric ionogenic species and their inherent transport to the detector. The prerequisite condition for application of this principle is the existence of an inverse electromigration dispersion profile, i.e. a profile where pH is decreasing toward the anode or cathode for focusing of anionic or cationic weak analytes, respectively. The theory presented defines the principal conditions under which an analyte is focused on a profile of this type. Since electromigration dispersion profiles are migrating ones, the new principle offers inherent transport of focused analytes into the detection cell. The focusing principle described utilizes a mechanism different from both CZE (where separation is based on the difference in mobilities) and IEF (where separation is based on difference in pI), and hence, offers another separation dimension in CE. The new principle and its theory presented here are supplemented by convincing experiments as their proof.
Steric effect and slip‐modulated energy transfer in narrow fluidic channels with finite aspect ratios
Authors: Garai Anirban , Chakraborty Suman
Published: February 2010

In this study, we delineate the combined consequences of finite channel aspect ratios, wall slip effects and steric interactions on the energy transfer mechanisms in narrow fluidic confinements. By considering the details of ionic interactions within the electrical double layer, we demonstrate that considerations of finite aspect ratios and steric effects may result in dramatic alterations in the predictions of effective viscosity as well as the energy transfer efficiency, particularly for high magnitudes of the surface charge density, as compared with the predictions based on parallel plate channel considerations. We also illustrate the possibilities of obtaining very high energy transfer efficiencies by employing channels of aspect ratios close to unity, with a judicious exploitation of steric interactions and wall slippage effects in highly confined geometries.
The use of essential oils for postharvest decay control. A review.
Authors: Antunes Maria Dulce C. , Cavaco Ana Margarida
Published: February 2010

Food safety is one of the major issues related to fresh fruit and vegetables. The preservation of the ‘freshness’ quality of these products is relevant due to their economical impact. This chapter is a comprehensive review of the use of essential oils from different sources and their constituents on the control of postharvest decay and overall quality preservation of fresh fruit and vegetables. An overview on the most significant postharvest diseases and their impact, as well as on the mainly used synthetic chemicals and their side‐effects has been included. Emphasis has been on the sources of essential oils and their constituents studied up to now, and their effects on controlling postharvest diseases, either in vitro or in vivo, and their effect on overall quality and storage life of fresh commodities. Issues regarding their impact on human health and the environment have also been analysed.
Anterior cervical osteophyte dysphagia: Manofluorographic and functional outcomes after surgery
Authors: Ozgursoy Ozan B. , Salassa John R. , Reimer Ronald , Wharen Robert E. , Deen Hugh G.
Published: February 2010

Background.

Our aim was to investigate the clinical and manofluorographic findings of patients with anterior cervical osteophyte (ACO) dysphagia before and after surgery.

Methods.

Chart review including manofluorography (MFG) data of patients undergoing ACO removal was undertaken.

Results.

Thirteen patients underwent transcervical ACO removal over a 10‐year period. A postoperative hematoma was the only surgical complication. Overall, there was a significant postoperative decrease in Functional Outcome Swallowing Scale (FOSS). MFG data showed an elevated preoperative intrabolus pressure gradient across the osteophyte (IB‐Gra), 39.78 mm Hg, and IB‐Gra significantly decreased to 19 mm Hg 6 months after surgery.

Conclusion.

Functional (FOSS) and objective MFG (IB‐Gra) improvements occurred in patients who had ACO dysphagia and underwent surgery. These findings support high IB‐Gra as a reliable objective indicator for surgical intervention for ACO dysphagia and IB‐Gra as an appropriate parameter for follow‐up after ACO removal. In selected patients, ACO removal by anterolateral‐transcervical approach is a safe and highly effective treatment. © 2010 Wiley Periodicals, Inc. Head Neck, 2010
Multimodal treatment of patients with minor salivary gland cancer in the case of recurrent disease
Authors: Erovic Boban M. , Schopper Christian , Pammer Johannes , Vormittag Laurenz , Maleki Amir , Brunner Markus , Heiduschka Gregor , Grasl Matthaeus Ch. , Thurnher Dietmar
Published: February 2010

Background

Our aim in this study was to identify prognostic factors and the optimal therapeutic management in patients with minor salivary gland carcinomas.

Methods

Overall and disease‐free survival and overall survival after recurrence in patients with adenoidcystic carcinoma (n = 25), mucoepidermoid carcinoma (n = 8), adenocarcinoma (n = 5), carcinoma ex pleomorphic adenoma (n = 4), and others (n = 5) were correlated to clinical data.

Results

Overall survival correlated to treatment modality (p = .039) and T classification (p = .003), whereas prolonged disease‐free interval correlated to treatment (p < .001) and T classification (p = .009). Overall survival after recurrence correlated to treatment of recurrence (p = .006) and initial T classification (p = .02). Multivariate analysis showed that overall survival after recurrence correlated to treatment of recurrence (p = .019) and initial T classification (p = 0.019). T classification was a prognostic factor for overall survival (p = .002) and disease‐free interval (p = .002).

Conclusions

The initial tumor classification is a clinical predictor for patients' overall and disease‐free survival and overall survival after recurrence. Multimodal treatment significantly improves patients' overall survival. © 2010 Wiley Periodicals, Inc. Head Neck, 2010
Designing a balanced scorecard for a tertiary care hospital in Pakistan: a modified Delphi group exercise
Authors: Rabbani Fauziah , Jafri Syed M. Wasim , Abbas Farhat , Shah Mairaj , Azam Syed Iqbal , Shaikh Babar Tasneem , Brommels Mats , Tomson Goran
Published: February 2010

Balanced Scorecards (BSC) are being implemented in high income health settings linking organizational strategies with performance data. At this private university hospital in Pakistan an elaborate information system exists. This study aimed to make best use of available data for better performance management. Applying the modified Delphi technique an expert panel of clinicians and hospital managers reduced a long list of indicators to a manageable size. Indicators from existing documents were evaluated for their importance, scientific soundness, appropriateness to hospital's strategic plan, feasibility and modifiability. Panel members individually rated each indicator on a scale of 1–9 for the above criteria. Median scores were assigned. Of an initial set of 50 indicators, 20 were finally selected to be assigned to the four BSC quadrants. These were financial (n = 4), customer or patient (n = 4), internal business or quality of care (n = 7) and innovation/learning or employee perspectives (n = 5). A need for stringent definitions, international benchmarking and standardized measurement methods was identified. BSC compels individual clinicians and managers to jointly work towards improving performance. This scorecard is now ready to be implemented by this hospital as a performance management tool for monitoring indicators, addressing measurement issues and enabling comparisons with hospitals in other settings Copyright © 2010 John Wiley & Sons, Ltd.
Consistency of signal intensity and T2* in frozen ex vivo heart muscle, kidney, and liver tissue
Authors: Kaye Elena A. , Josan Sonal , Lu Aiming , Rosenberg Jarrett , Daniel Bruce L. , Pauly Kim Butts
Published: February 2010

Purpose:

To investigate tissue dependence of the MRI‐based thermometry in frozen tissue by quantification and comparison of signal intensity and T2* of ex vivo frozen tissue of three different types: heart muscle, kidney, and liver.

Materials and Methods:

Tissue samples were frozen and imaged on a 0.5 Tesla MRI scanner with ultrashort echo time (UTE) sequence. Signal intensity and T2* were determined as the temperature of the tissue samples was decreased from room temperature to approximately −40°C. Statistical analysis was performed for (−20°C, −5°C) temperature interval.

Results:

The findings of this study demonstrate that signal intensity and T2* are consistent across three types of tissue for (−20°C, −5°C) temperature interval.

Conclusion:

Both parameters can be used to calculate a single temperature calibration curve for all three types of tissue and potentially in the future serve as a foundation for tissue‐independent MRI‐based thermometry. J. Magn. Reson. Imaging 2010;31:719–724. © 2010 Wiley‐Liss, Inc.
Smoothing that does not blur: Effects of the anisotropic approach for evaluating diffusion tensor imaging data in the clinic
Authors: Moraschi Marta , Hagberg Gisela E. , Di Paola Margherita , Spalletta Gianfranco , Maraviglia Bruno , Giove Federico
Published: February 2010

Purpose:

To compare the effects of anisotropic and Gaussian smoothing on the outcomes of diffusion tensor imaging (DTI) voxel‐based (VB) analyses in the clinic, in terms of signal‐to‐noise ratio (SNR) enhancement and directional information and boundary structures preservation.

Materials and Methods:

DTI data of 30 Alzheimer's disease (AD) patients and 30 matched control subjects were obtained at 3T. Fractional anisotropy (FA) maps with variable degrees and quality (Gaussian and anisotropic) of smoothing were created and compared with an unsmoothed dataset. The two smoothing approaches were evaluated in terms of SNR improvements, capability to separate differential effects between patients and controls by a standard VB analysis, and level of artifacts introduced by the preprocessing.

Results:

Gaussian smoothing regionally biased the FA values and introduced a high variability of results in clinical analysis, greatly dependent on the kernel size. On the contrary, anisotropic smoothing proved itself capable of enhancing the SNR of images and maintaining boundary structures, with only moderate dependence of results on smoothing parameters.

Conclusion:

Our study suggests that anisotropic smoothing is more suitable in DTI studies; however, regardless of technique, a moderate level of smoothing seems to be preferable considering the artifacts introduced by this manipulation. J. Magn. Reson. Imaging 2010;31:690–697. © 2010 Wiley‐Liss, Inc.
Perfusion parameters derived from bolus‐tracking perfusion imaging are immune to tracer recirculation
Authors: Kosior Jayme Cameron , Frayne Richard
Published: February 2010

Purpose:

To investigate the impact of tracer recirculation on estimates of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT).

Materials and Methods:

The theoretical model used to derive CBF, CBV, and MTT was examined. CBF and CBV estimates with and without tracer recirculation were compared in computer simulations to examine the effects of tracer recirculation.

Results:

The equations used to derive CBF, CBV, and MTT assume that the arterial input function and tissue tracer signals define the input and output signals, respectively, of a linear time‐invariant system. As a result of the principle of superposition, these perfusion parameters are immune to tracer recirculation, which was confirmed by computer simulation. However, limited acquisition durations can lead to CBV and CBF errors of up to 50%.

Conclusion:

Tracer recirculation does not impact estimation of CBF, CBV, or MTT. However, previous approaches used to remove recirculation effects may be beneficial when used to compensate for limited acquisition durations in which the passage of the bolus is not adequately captured. J. Magn. Reson. Imaging 2010;31:753–756. © 2010 Wiley‐Liss, Inc.
Whole‐body MR imaging for the evaluation of mcCune‐albright syndrome
Authors: Ferreira Elisa C. , Brito Cecília C.B. , Domingues Roberto C. , Bernardes Marcio , Marchiori Edson , Gasparetto Emerson L.
Published: February 2010

This paper is a detailed case study of a seven‐year‐old girl who developed precocious puberty. The young girl experienced bilateral breast enlargement, vaginal discharge, and multiple areas of “cafe‐au‐lait” pigmentation on the skin. The skeletal radiographs showed multiple bone lesions which were suggestive of polyostotic fibrous dysplasia. These findings were sufficient to establish the diagnosis of McCune‐Albright syndrome. Whole‐body MRI was used to assess the extent of the osseous lesions throughout the body. The MRI showed approximately the same number of osseous lesions compared to the skeletal radiographs. In addition, the MRI detected a cystic lesion localized in the pelvis that raised the possibility of an ovarian‐follicular cyst. This case suggests that whole‐body MRI might be a promising method for the evaluation and follow‐up of polyostotic fibrous dysplasia, a disease with diffuse involvement of the musculoskeletal system. J. Magn. Reson. Imaging 2010;31:706–710. © 2010 Wiley‐Liss, Inc.