bluuebunny/crossref_metadata_2025 huggingface dataset:
Enzymatic hydrolysis of cellulose coupled with electricity generation in a microbial fuel cell
Authors: Rezaei Farzaneh , Richard Tom L. , Logan Bruce E.
Published: June 2008

Electricity can be directly generated by bacteria in microbial fuel cells (MFCs) from a variety of biodegradable substrates, including cellulose. Particulate materials have not been extensively examined for power generation in MFCs, but in general power densities are lower than those produced with soluble substrates under similar conditions likely as a result of slow hydrolysis rates of the particles. Cellulases are used to achieve rapid conversion of cellulose to sugar for ethanol production, but these enzymes have not been previously tested for their effectiveness in MFCs. It was not known if cellulases would remain active in an MFC in the presence of exoelectrogenic bacteria or if enzymes might hinder power production by adversely affecting the bacteria. Electricity generation from cellulose was therefore examined in two‐chamber MFCs in the presence and absence of cellulases. The maximum power density with enzymes and cellulose was 100 ± 7 mW/m2 (0.6 ± 0.04 W/m3), compared to only 12 ± 0.6 mW/m2 (0.06 ± 0.003 W/m3) in the absence of the enzymes. This power density was comparable to that achieved in the same system using glucose (102 ± 7 mW/m2, 0.56 ± 0.038 W/m3) suggesting that the enzyme successfully hydrolyzed cellulose and did not otherwise inhibit electricity production by the bacteria. The addition of the enzyme doubled the Coulombic efficiency (CE) to CE = 51% and increased COD removal to 73%, likely as a result of rapid hydrolysis of cellulose in the reactor and biodegradation of the enzyme. These results demonstrate that cellulases do not adversely affect exoelectrogenic bacteria that produce power in an MFC, and that the use of these enzymes can increase power densities and reactor performance. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc.
Increasing yeast secretion of heterologous proteins by regulating expression rates and post‐secretory loss
Authors: Huang Dagang , Gore Patrick R. , Shusta Eric V.
Published: June 2008

Heterologous protein secretion involves the coupled processes of protein synthesis, protein folding, and secretory trafficking. A more complete understanding of how these processes interrelate could help direct optimization of secretion systems. Here we provide a detailed study regarding the dynamics of heterologous protein secretion from yeast in terms of intracellular protein levels, secreted protein levels, and unfolded protein response (UPR). Three different protein expression induction temperatures (20, 30, and 37°C) were investigated as a means to modulate expression rates and thus cellular responses. Inducing at 20°C yielded the slowest initial secretion rate, but the highest absolute level of product. Correspondingly, the level and the rate of both intracellular protein accumulation and unfolded protein response (UPR) activation were also the lowest at 20°C. In addition, secretion ceased after approximately 22 h at 30 and 37°C, respectively, while it was continuous until nutrient depletion at 20°C. Maxima in secretion levels were observed that were a result of the additive effects of secretion cessation and post‐secretory protein loss. The post‐secretory loss of protein did not appear to result from solution phase proteolysis or aggregation, but required the presence of yeast cells. Refeeding of both yeast nitrogen base and casamino acids successfully prevented the post‐secretory loss of protein at both high (37°C) and low (20°C) temperatures, and further increased secretion levels 1.5‐fold at 20°C where the secretory pathway was still functioning. Taken together, these findings suggest that there exists an appropriate balance between protein synthesis, processing and secretion rates required for secretion optimization. Biotechnol. Bioeng. © 2008 Wiley Periodicals, Inc.
Teleconferencing model for forensic consultation, court testimony, and continuing education
Authors: Miller Thomas W. , Clark James , Veltkamp Lane J. , Burton Deborah C. , Swope Marian
Published: June 2008

A medical center‐based forensic clinic that provides the necessary comprehensive consultation, continuing education, court testimony, and clinical services through an applied model of teleconferencing applications is addressed. Telemedicine technology and services have gained the attention of both legal and clinical practitioners, examining trends and models of health care for underserved populations, and identifying where consultation with a team of professionals may benefit service providers in rural communities. The contribution offered herein provides an understanding of the history of the development of the clinic, a theoretical model that has been applied to a clinical forensic program that employs telepsychiatry services, and the ethical and malpractice liability issues confronted in using teleconferencing services. This model is examined through a child and adolescent forensic evaluation clinic. The goals of this model are offered, as are a number of applications within the broad spectrum of services utilizing telemedicine. Finally, changing patterns are addressed in clinically based health‐care delivery for criminal justice, social services, and forensic mental health. Copyright © 2008 John Wiley & Sons, Ltd.
Forensic telepsychiatry in the United Kingdom
Authors: Saleem Younus , Taylor Mark H. , Khalifa Najat
Published: June 2008

Forensic telepsychiatry remains in its infancy in the United Kingdom. This article sets out to describe how it can be used within a community forensic service, and the future challenges ahead in the United Kingdom. It looks at relevant academic, governmental, and legal resources and is designed as a scholarly reflection by clinicians rather than as a formal literature review. Copyright © 2008 John Wiley & Sons, Ltd.
Empirical evidence on the use and effectiveness of telepsychiatry via videoconferencing: Implications for forensic and correctional psychiatry
Authors: Antonacci Diana J. , Bloch Richard M. , Saeed Sy Atezaz , Yildirim Yilmaz , Talley Jessica
Published: June 2008

A growing body of literature now suggests that use of telepsychiatry to provide mental health services has the potential to solve the workforce shortage problem that directly affects access to care, especially in remote and underserved areas. Live interactive two‐way audio–video communication—videoconferencing—is the modality most applicable to psychiatry and has become synonymous with telepsychiatry involving patient care, distance education, and administration. This article reviews empirical evidence on the use and effectiveness of videoconferencing in providing diagnostic and treatment services in mental health settings that serve child, adolescent, and adult populations. Descriptive reports, case studies, research articles, and randomized controlled trials related to clinical outcomes were identified and reviewed independently by two authors. Articles related to cost‐effectiveness, technological issues, or legal or ethical aspects of telepsychiatry were excluded. The review of the evidence broadly covers mental health service provision in all settings, including forensic settings. Given the sparse literature on telepsychiatry in forensic settings, we discuss implications for mental health care across settings and populations and comment on future directions and potential uses in forensic or correctional psychiatry. Copyright © 2008 John Wiley & Sons, Ltd.
Telepsychiatry with rural American Indians: issues in civil commitments
Authors: Shore Jay H. , Bloom Joseph D. , Manson Spero M. , Whitener Ron J.
Published: June 2008

The use of live interactive videoconferencing to provide psychiatric care, telepsychiatry, has particular relevance for improving mental health treatment to rural American Indian reservations. There is little literature on civil commitments in telepsychiatry and none specifically addressing this topic among American Indians. This article reviews telepsychiatry in the mental health care of American Indians, civil commitments and telepsychiatry in general, and the current state of civil commitments in American Indian communities. We conclude by considering commitment through telepsychiatry in rural reservations and offering guidelines to assist practitioners in navigating this challenging landscape. Civil commitments of American Indian patients residing in rural reservations can be successfully accomplished through videoconferencing by thoughtful and informed clinicians. However, much more work is needed in this area, including research into the cultural attitudes and perspectives towards commitments and further inquiry regarding potential legal precedents, as well as case reports and examples of this work. Copyright © 2008 John Wiley & Sons, Ltd.
Videoconferencing and forensic mental health in Australia
Authors: Sullivan Danny H. , Chapman Murray , Mullen Paul E.
Published: June 2008

Videoconferencing is in common use in Australian forensic mental health services. It provides opportunities to link remote prisons, courts, and psychiatric clinics with distant specialist services, and enables a range of activities including assessment, treatment and feedback, expert testimony, education, and inter‐service planning. These functions are acceptable to patients and clinicians, and in Australia videoconferencing minimizes disruption to small services and their patients, who might otherwise face lengthy journeys. In particular, marginalized patient groups, including indigenous people and prisoners, may receive better services. The evidence base supports use of videoconferencing despite a number of practical, legal, and clinical issues that may reduce its effectiveness compared with face‐to‐face assessments. Videoconferencing technologies are critical to effective forensic mental health services in Australia. Copyright © 2008 John Wiley & Sons, Ltd.
Selenoglutaredoxin as a Glutathione Peroxidase Mimic
Authors: Casi Giulio , Roelfes Gerard , Hilvert Donald
Published: June 2008

Glutaredoxin (Grx1) from Escherichia coli is a monomeric, 85‐amino‐acid‐long, disulfide‐containing redox protein. A Grx1 variant in which the redox‐active disulfide was replaced with a selenocysteine (C11U/C14S) was prepared by native chemical ligation from three fragments as a potential mimic of the natural selenoenzyme glutathione peroxidase (Gpx). Selenoglutaredoxin, like the analogous C14S Grx1 variant, shows weak peroxidase activity. The selenol provides a 30‐fold advantage over the thiol, but its activity is four orders of magnitude lower than that of bovine Gpx. In contrast, selenoglutaredoxin is an excellent catalyst for thiol–disulfide exchange reactions; it promotes the reduction of β‐hydroxyethyldisulfide by glutathione with a specific activity of 130 units mg−1. This value is 1.8 times greater than that of C14S Grx1 under identical conditions, and >104 greater than the peroxidase activity of either enzyme. Given the facile reduction of the glutathionyl‐selenoglutaredoxin adduct by glutathione, oxidation of the selenol by the alkyl hydroperoxide substrate likely limits catalytic turnover and will have to be optimized to create more effective Gpx mimics. These results highlight the challenge of generating Gpx activity in a small, generic protein scaffold, despite the presence of a well‐defined glutathione binding site and the intrinsic advantage of selenium over sulfur derivatives.
General Synthesis and Aggregation Behaviour of New Single‐Chain Bolaphospholipids: Variations in Chain and Headgroup Structures
Authors: Drescher Simon , Meister Annette , Graf Gesche , Hause Gerd , Blume Alfred , Dobner Bodo
Published: June 2008

The chemical structures of polymethylene‐1,ω‐bis(phosphocholines) that self‐assemble into nanofibres was modified on the one hand in the hydrophobic chain region, by introduction of sulfur and oxygen atoms, and on the other hand by variation of the polar headgroup structure with functionalised tertiary amines. The temperature‐dependent self‐assembly of these novel bolaphospholipids into nanofibres and spherical micelles was investigated by differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). The thermal stabilities of the nanofibres strongly depend on the chemical compositions of the headgroups and of the hydrophobic chains. The insertion of new functionalities in the headgroup region by click chemistry makes these substances interesting for potential applications in bioscience and materials science.
Insights into the Post‐Translational Methylation of Arginine from Studies of Guanidinium–Water Nanodroplets
Authors: McQuinn Keri , McIndoe J. Scott , Hof Fraser
Published: June 2008

Highly solvated methylated guanidinium ions ([MenGuan(H2O)m]+; n=0–4 and 6; m=1–>50), which model the various post‐translationally methylated states of arginine, were generated in the electrospray ionization (ESI) source of an unmodified commercial tandem mass spectrometer. The dehydration processes of highly solvated [MenGuan(H2O)21]+ ions were monitored by using energy‐dependent ESI MS. These data, together with supporting calculations, provide a detailed picture of the interplay of methylation and hydration, and both the calculations and the experimental evidence suggest a specific structural basis for the observed effects. The ramifications for biochemical binding events that are controlled by the post‐translational methylation of arginine to give dimethylarginines are discussed.
Expression of the fast twitch troponin complex, fTnT, fTnI and fTnC, in vascular smooth muscle
Authors: Moran Carlos M. , Garriock Robert J. , Miller Melanie K. , Heimark Ronald L. , Gregorio Carol C. , Krieg Paul A.
Published: June 2008

It is generally believed that proteins of the troponin complex are not expressed in smooth muscle. We have directly assayed for expression of troponin transcripts in mouse vascular smooth muscle and found that troponin sequences normally associated with fast twitch skeletal muscle (fTnT, fTnI, fTnC) were present at significant levels in the thoracic aorta. In situ hybridization experiments demonstrated that fTnT, fTnI and fTnC transcripts were expressed in the smooth muscle layer of mouse blood vessels of all sizes. Protein blot analysis using rat tissue showed that at least two members of the troponin complex, Troponin T and Troponin I, were translated in vascular smooth muscle of the aorta. Finally, immuno‐fluorescence microscopy of rat aortic smooth muscle revealed that TnT and TnI are localized in a unique pattern, coincident with the distribution of tropomyosin. It seems likely therefore, that a complete troponin complex is expressed in vascular smooth muscle and is associated with the contractile machinery of the cell. These observations raise the possibility that troponins play a role in regulation of smooth muscle function. Cell Motil. Cytoskeleton 2008. © 2008 Wiley‐Liss, Inc.
Up‐regulation of CD40 with juxtacrine activity in human nonsmall lung cancer cells correlates with poor prognosis
Authors: Ishikawa Keidai , Miyamoto Masaki , Yoshioka Tatsuya , Kato Tatsuya , Kaji Mitsuhito , Ohbuchi Toshiro , Hirano Satoshi , Itoh Tomoo , Dosaka‐Akita Hirotoshi , Kondo Satoshi
Published: June 2008

BACKGROUND.

CD40 and its ligand, CD154, play a regulatory role in several signaling pathways among lymphocytes. Recently, it was reported that CD40 is expressed in several malignant tumors. However, the clinical impact of CD40 expression in nonsmall cell lung cancer has not been studied widely.

METHODS.

One hundred twenty‐nine surgical specimens of nonsmall cell lung cancer were assessed immunohistochemically for CD40 and CD154 expression, and that expression was correlated with patients' clinicopathologic parameters and outcome. Subsequently, in vitro analysis of CD40‐CD154 signaling was performed.

RESULTS.

Immunohistochemical staining of tumor cells confirmed that 67 patients (51.9%) were positive for CD40, and 76 patients (58.9%) were positive for CD154. The survival of patients who had tumors that were negative for CD40 was significantly better than the survival of patients who had tumors that were positive for CD40 (P = .0004). Multivariate analysis using a Cox regression model indicated that CD40 expression in cancer cells is an independent, unfavorable prognostic factor (risk ratio, 1.855; P = .0403). By using an in vitro juxtacrine growth factor assay, the growth of LK2 cells (CD40‐positive/CD154‐negative) was accelerated by CD154‐positive cancer cells, such as PC10 cells (CD40‐negative/CD154‐positive), by a juxtacrine mechanism.

CONCLUSIONS.

The current results suggested that CD40 expression in tumors is associated with a poor prognosis and that the juxtacrine interaction of CD40‐CD154 among cancer cells facilitates the development of malignant potential in nonsmall cell lung cancer. Cancer 2008. © 2008 American Cancer Society.
Intracellular Phospho‐Flow cytometry reveals novel insights into TCR proximal signaling events. A comparison with Western blot
Authors: Haas Anna , Weckbecker Gisbert , Welzenbach Karl
Published: June 2008

Phospho‐site specific antibodies become increasingly available, enabling the study of signaling events by Western blotting (WB) or intracellular flow cytometry (Phospho‐Flow). Here we compared data generated by WB or Phospho‐Flow regarding the kinetics and degree of phosphorylation of membrane proximal TCR signaling molecules. Phosphorylation events in Jurkat T cells were triggered by anti‐CD3 stimulation (OKT3) or by oxidative stress (H2O2) and were analyzed by Phospho‐Flow or WB. Both techniques showed that OKT3‐ or H2O2‐induced, transient phosphorylation of ZAP70 or LAT was dependent on functional Lck. Phospho‐Flow data revealed differences in the kinetics and the degree of H2O2‐ or OKT3‐mediated protein phosphorylation compared with WB data. In addition, using Phospho‐Flow we discovered that H2O2‐induced phosphorylation of TCR signaling proteins was inhibited by small molecular weight kinase inhibitors far more potently than OKT3‐triggered protein phosphorylation, despite a superior induction of phosphorylation by H2O2.This finding was confirmed by WB. Interestingly, we identified by Phospho‐Flow that, in P116 Jurkat cells lacking ZAP70 protein expression, H2O2 potently triggered the phosphorylation of ZAP70 residues Y493 and Y292 but not Y319. The phosphorylation of these ZAP70 tyrosine residues cells was blocked by an Lck inhibitor, suggesting the existence of an Lck‐coupled truncated ZAP70 protein or a novel isoform of ZAP70 in P116 cells. Phospho‐Flow is a largely quantitative technology with excellent throughput, highly suited in studying the function or inhibition of TCR signaling pathways and allowing the detection of novel pathway insights. It can serve as a good complement to Western blot analysis. © 2008 International Society for Advancement of Cytometry
Dietary retinoic acid affects song maturation and gene expression in the song system of the zebra finch
Authors: Wood William E. , Olson Christopher R. , Lovell Peter V. , Mello Claudio V.
Published: June 2008

Vitamin A, an essential nutrient, is required in its acidic form (retinoic acid) for normal embryogenesis and neuronal development, typically within well‐defined concentration ranges. In zebra finches, a songbird species, localized retinoic acid synthesis in the brain is important for the development of song, a learned behavior sharing significant commonalities with speech acquisition in humans. We tested how dietary retinoic acid affects the development of song behavior and the brain's system for song control. Supplemental doses of retinoic acid given to juveniles during the critical period for song learning resulted in more variable or plastic‐like songs when the birds reached adulthood, compared to the normal songs of vehicle‐fed controls. We also observed that several genes (brinp1, nrgn, rxr‐α, and sdr2/scdr9) had altered levels of expression in specific nuclei of the song system when comparing the experimental and control diet groups. Interestingly, we found significant correlations between gene expression levels in nuclei of the anterior forebrain pathway (lMAN and area X) and the degree of variability in the recorded songs. We observed, however, no major morphological effects such as changes in the volumes of song nuclei. Overall, our results lend further support to a fundamental role of retinoic acid in song maturation and point to possible molecular pathways associated with this action. The data also demonstrate that dietary content of Vitamin A can affect the maturation of a naturally learned complex behavior. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008
Identification of Drosophila type II neuroblast lineages containing transit amplifying ganglion mother cells
Authors: Boone Jason Q. , Doe Chris Q.
Published: June 2008

Mammalian neural stem cells generate transit amplifying progenitors that expand the neuronal population, but these type of progenitors have not been studied in Drosophila. The Drosophila larval brain contains ∼100 neural stem cells (neuroblasts) per brain lobe, which are thought to bud off smaller ganglion mother cells (GMCs) that each produce two post‐mitotic neurons. Here, we use molecular markers and clonal analysis to identify a novel neuroblast cell lineage containing “transit amplifying GMCs” (TA‐GMCs). TA‐GMCs differ from canonical GMCs in several ways: each TA‐GMC has nuclear Deadpan, cytoplasmic Prospero, forms Prospero crescents at mitosis, and generates up to 10 neurons; canonical GMCs lack Deadpan, have nuclear Prospero, lack Prospero crescents at mitosis, and generate two neurons. We conclude that there are at least two types of neuroblast lineages: a Type I lineage where GMCs generate two neurons, and a type II lineage where TA‐GMCs have longer lineages. Type II lineages allow more neurons to be produced faster than Type I lineages, which may be advantageous in a rapidly developing organism like Drosophila. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008
The development of intrinsic excitability in mouse retinal ganglion cells
Authors: Qu Juan , Myhr Karen L.
Published: June 2008

Activity‐dependent refinement of synaptic connections occurs throughout the developing nervous system, including the visual system. Retinal ganglion cells (RGCs) overproduce synapses then refine them in an activity‐dependent manner that segregates RGC connections into multicellular patterns, such as eye‐specific regions and retinotopic maps. Ferrets additionally segregate ON and OFF retinogeniculate pathways in an activity‐dependent manner. It was unknown whether differences in ON versus OFF intrinsic and spontaneous activity occur in postnatal mouse. The work reported here measured the intrinsic properties and spontaneous activity of morphologically identified postnatal mouse RGCs, and tested the hypothesis that mouse ON and OFF RGCs develop differences in spontaneous activity. We found developmental changes in resting potential, action potential threshold, depolarization to threshold, action potential width, action potential patterns, and maximal firing rates. These results are consistent with the maturation of the intrinsic properties of RGCs extending through the first three postnatal weeks. However, there were no differences among mouse ON, OFF, and multistratified RGCs in intrinsic excitability, spontaneous synaptic drive or spontaneous action potential patterns. The absence of differences between ON and OFF activity patterns is unlike the differences that arise in ferrets. In contrast to the ferret, the ON and OFF target neurons in the mouse are organized in a random pattern, not layers. This supports the hypothesis that the absence of systematic differences in activity results in the nonlayered distribution of retinogeniculate connections. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008
Normal dendrite growth in Drosophila motor neurons requires the AP‐1 transcription factor
Authors: Hartwig Cortnie L. , Worrell Jason , Levine Richard B. , Ramaswami Mani , Sanyal Subhabrata
Published: June 2008

During learning and memory formation, information flow through networks is regulated significantly through structural alterations in neurons. Dendrites, sites of signal integration, are key targets of activity‐mediated modifications. Although local mechanisms of dendritic growth ensure synapse‐specific changes, global mechanisms linking neural activity to nuclear gene expression may have profound influences on neural function. Fos, being an immediate‐early gene, is ideally suited to be an initial transducer of neural activity, but a precise role for the AP‐1 transcription factor in dendrite growth remains to be elucidated. Here we measure changes in the dendritic fields of identified Drosophila motor neurons in vivo and in primary culture to investigate the role of the immediate‐early transcription factor AP‐1 in regulating endogenous and activity‐induced dendrite growth. Our data indicate that (a) increased neural excitability or depolarization stimulates dendrite growth, (b) AP‐1 (a Fos, Jun hetero‐dimer) is required for normal motor neuron dendritic growth during development and in response to activity induction, and (c) neuronal Fos protein levels are rapidly but transiently induced in motor neurons following neural activity. Taken together, these results show that AP‐1 mediated transcription is important for dendrite growth, and that neural activity influences global dendritic growth through a gene‐expression dependent mechanism gated by AP‐1. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008
Three‐Dimensionally Ordered CDW State in Quasi‐One‐Dimensional Iodo‐Bridged Dinuclear Platinum Mixed‐Valence Compounds, A4[Pt2I(pop)4]·nH2O (A = Aromatic Ammonium Cations)
Authors: Matsunaga Satoshi , Takizawa Kouichi , Kawakami Daisuke , Iguchi Hiroaki , Takaishi Shinya , Kajiwara Takashi , Miyasaka Hitoshi , Yamashita Masahiro , Matsuzaki Hiroyuki , Okamoto Hiroshi
Published: June 2008

Linear‐chain iodo‐bridged dinuclear Pt mixed‐valence compounds with aromatic ammonium countercations, A4[Pt2I(pop)4]·nH2O [pop = P2O5H22–, A = benzyl ammonium (n = 2; 1), anilinium (n = 2; 2), and p‐methoxy anilinium (n = 2; 3)], that have three‐dimensionally ordered structures were synthesized. In the case of 1–3 the aromatic ammonium countercations were located between neighboring Pt chains and stacked in 1D columns. π–π Interactions between the phenyl rings and hydrogen bonds between the –NH3+ moieties and the oxygen atoms of the pop ligand link the Pt chains together, thus giving rise to a three‐dimensionally ordered CDW state. This is the first observation of this phenomenon in compounds of this type.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Unprecedented N‐Inserted Disulfide Ligand Stabilized by Coordination to the Electropositive CoIII Center
Authors: Yoo Houng Sik , Yoon Jung Hee , Kim Jae Il , Koh Eui Kwan , Hong Chang Seop
Published: June 2008

The reaction of CoII and 2,2′‐dipyridyldisulfide (PySSPy) in the presence of azide produced a peculiar monomeric complex [CoIII(PyS)(PyS‐N‐SPy)(N3)] (1). In this reaction, redox chemistry takes place, which is associated mainly with the oxidation of CoII to CoIII and the reduction of PySSPy. During the reaction, the azide ion decomposes and donates a nitrogen atom to PySSPy. The crystal structure of 1 provides evidence that the unusual, N‐inserted ligand PyS‐N‐SPy can be stabilized through coordination to the electropositive CoIII ion. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Superacid‐Catalyzed Dimerization/Cyclization of Isopropenyl‐PAHs – Novel Pathways to PAH Dimers, Phenalenes and Their Stable Carbocations
Authors: Brulé Cédric , Sultana Fatima , Hollenstein Sandro , Okazaki Takao , Laali Kenneth K.
Published: June 2008

The isopropenyl derivatives of representative classes of polycyclic aromatic hydrocarbons (PAHs) having four and five fused‐ring systems, namely pyrene, chrysene, benzo[c]phenanthrene (BcPh), dibenzo[a,c]anthracene (benzo[f]tetraphene) and perylene, were synthesized by Wittig olefination from the corresponding acetyl‐PAHs. Under the influence of triflic acid (TfOH), the isopropenyl derivatives were converted to novel PAH dimers and/or phenalenes in a simple one‐pot procedure. A plausible mechanism for this process has been outlined, and the synthetic scope of this chemistry has been explored. Structural features in the PAH dimers were examined by DFT. As representative initial and final carbocation intermediates in the reaction sequence, stable carbocations derived from 3‐isopropenylperylene and from 4,6,6‐trimethyl‐6H‐dibenzo[a,kl]anthracene were generated and studied directly by NMR spectroscopy. The NMR characteristics and charge delocalization modes in the resulting benzylic carbocations are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Bovine red blood cell starvation age discrimination through a glutaraldehyde‐amplified dielectrophoretic approach with buffer selection and membrane cross‐linking
Authors: Gagnon Zachary , Gordon Jason , Sengupta Shramik , Chang Hsueh‐Chia
Published: June 2008

We report a novel buffer electric and dielectric relaxation time tuning technique, coupled with a glutaraldehyde (Glt.) cross‐linking cell fixation reaction that allows for sensitive dielectrophoretic analysis and discrimination of bovine red blood cells of different starvation age. Guided by a single‐shell oblate spheroid model, a zwitterion buffer composition is selected to ensure that two measurable crossover frequencies (cof's) near 500 kHz exist for dielectrophoresis (DEP) within a small range of each other. It is shown that the low cof is sensitive to changes in the cell membrane dielectric constant, in which cross‐linking by Glt. reduces the dielectric constant of the cell membrane from 10.5 to 3.8, while the high cof is sensitive to cell cytoplasm conductivity changes. We speculate that this enhanced particle polarizability that results from the cross‐linking reaction is because younger (reduced starvation time) cells possess more amino groups that the reaction can release to enhance the cell interior ionic strength. Such sensitive discrimination of cells with different age (surface protein density) by DEP is not possible without the zwitterion buffer and cleavage by Glt. treatment. It is then expected that rapid identification and sorting of healthy from diseased cells can be similarly sensitized.
Bulk electrical properties of single‐walled carbon nanotubes immobilized by dielectrophoresis: Evidence of metallic or semiconductor behavior
Authors: Mureau Natacha , Watts Paul C. P. , Tison Yann , Silva S. Ravi P.
Published: June 2008

We report the electrical characterization of single‐walled carbon nanotubes (SWCNTs) trapped between two electrodes by dielectrophoresis (DEP). At high frequency, SWCNTs collected by DEP are expected to be of metallic type. Indeed current‐voltage (I‐V) measurements for devices made at 10 MHz show high values of conductivity and exhibit metallic behavior with linear and symmetric electrical features attributed to ohmic conduction. At low frequency, SWCNTs attracted by DEP are expected to be of semiconducting nature. Devices made at 10 kHz behave as semiconductors and demonstrate nonlinear and rectifying electrical characteristics with conductivities many orders of magnitude below the sample resulting from high‐frequency immobilization of SWCNTs. Conducting atomic force microscopy (C‐AFM) and current density calculation results are presented to reinforce results obtained by I‐V measurements which clearly show type separation of SWCNTs after DEP experiments.
Cortical compensation associated with dysphagia caused by selective degeneration of bulbar motor neurons
Authors: Dziewas Rainer , Teismann Inga K. , Suntrup Sonja , Schiffbauer Hagen , Steinstraeter Olaf , Warnecke Tobias , Ringelstein Erich‐Bernd , Pantev Christo
Published: June 2008

According to recent neuroimaging studies, swallowing is processed within multiple regions of the human brain. In contrast to this, little is known about the cortical contribution and compensatory mechanisms produced by impaired swallowing. In the present study, we therefore investigated the cortical topography of volitional swallowing in patients with X‐linked bulbospinal neuronopathy (Kennedy disease, KD). Eight dysphagic patients with genetically proven KD and an age‐matched healthy control group were studied by means of whole‐head magnetoencephalography using a previously established swallowing paradigm. Analysis of data was carried out with synthetic aperture magnetometry (SAM). The group analysis of individual SAM results was performed using a permutation test. KD patients showed significantly larger swallow‐related activation of the bilateral primary sensorimotor cortex than healthy controls. In contrast to the control group, in KD patients the maximum activity was located in the right sensorimotor cortex. Furthermore, while in nondysphagic subjects a previously described time‐dependent shift from the left to the right hemisphere was found during the one second of most pronounced swallow‐related muscle activity, KD patients showed a strong right hemispheric activation in each time segment analyzed. Since the right hemisphere has an established role in the coordination of the pharyngeal phase of swallowing, the stronger right hemispheric activation observed in KD patients indicates cortical compensation of pharyngeal phase dysphagia. Hum Brain Mapp 2009. © 2008 Wiley‐Liss, Inc.
Paired‐pulse depression of excitatory postsynaptic current sinks in hippocampal CA1 in vivo
Authors: Leung L. Stan , Peloquin Pascal , Canning Kevin J.
Published: June 2008

Paired‐pulse depression (PPD), a short‐term neural plasticity, was studied in hippocampal CA1 of urethane‐anesthetized rats in vivo, using field potential recordings and current source density analysis. PPD was robust when an ipsilateral CA3 (iCA3) conditioning pulse of moderate stimulus intensity was followed 30–200 ms later by a contralateral CA3 (cCA3) test pulse; the ratio of the conditioned (C) to the nonconditioned (NC) response, as measured by the peak excitatory sink at the apical dendrites, ranged from 0.6 to 0.8. An alveus conditioning pulse evoked a large antidromic population spike in CA1 and a modest depression of the CA3‐evoked excitatory sink (C/NC ratio of ∼0.85). High‐intensity paired pulses, both delivered to iCA3, also showed PPD of the proximal excitatory sinks; however, paired‐pulse facilitation of the dendritic sinks was found at the mid‐apical dendrites, >250 μm from the soma. Local injection of GABAA antagonist picrotoxin or bicuculline increased the C/NC ratio at IPIs of <150 ms, as well as the ratio of the amplitude of the population spikes (P2/P1; where P2 and P1 are the population spikes evoked by the second and first pulse, respectively). GABAB receptor antagonists, CGP35348 given intracerebroventricularly or CGP56999A administered locally, increased C/NC and P2/P1 at IPIs of 150–400 ms. It is concluded that conditioned depression of the excitatory sinks was caused by mainly feedforward and some feedback inhibition at the apical dendrites. GABAA‐mediated postsynaptic inhibition dominated at early latencies, while GABAB‐mediated inhibition prevailed at long latencies, probably at both presynaptic and postsynaptic sites. PPD of the excitatory sinks provides a measure of population dendritic inhibition in vivo. © 2008 Wiley‐Liss, Inc.
S‐ketamine and GABA‐A‐receptor interaction in humans: an exploratory study with I‐123‐iomazenil SPECT
Authors: Heinzel Alexander , Steinke Rainer , Poeppel Thorsten Dirk , Grosser Oliver , Bogerts Bernhard , Otto Hans , Northoff Georg
Published: June 2008

Objective

We aimed to probe for regional cerebral effects of S‐ketamine on in vivo GABA‐A‐receptor binding in healthy human subjects.

Methods

We investigated I‐123‐iomazenil SPECT before, during and after administration of S‐ketamine in a blinded placebo‐controlled study design (n = 12 in both groups). Analyses of SPECT were performed with voxel‐based statistical parametric mapping (SPM), and statistical comparisons were made between the groups. We also assessed biochemical and behavioural changes during S‐ketamine infusion.

Results

S‐ketamine induced positive and negative symptoms measured by the Brief Psychiatric Rating scale (BPRS). It increased the cortisol and prolactin levels. Image analysis revealed significantly decreased I‐123‐iomazenil binding in bilateral dorsomedial prefrontal cortex during S‐ketamine administration when compared to placebo.

Conclusion

Our study delivers preliminary evidence for an in vivo interaction of S‐ketamine with GABA‐A‐receptors in human dorsomedial prefrontal cortex. Copyright © 2008 John Wiley & Sons, Ltd.
Activation of NF‐κB by extracellular S100A4: Analysis of signal transduction mechanisms and identification of target genes
Authors: Boye Kjetil , Grotterød Ida , Aasheim Hans‐Christian , Hovig Eivind , Mælandsmo Gunhild M.
Published: June 2008

The metastasis‐promoting protein S100A4 stimulates metastatic progression through both intracellular and extracellular functions. Extracellular activities of S100A4 include stimulation of angiogenesis, regulation of cell death and increased cell motility and invasion, but the exact molecular mechanisms by which extracellular S100A4 exerts these effects are incompletely elucidated. The aim of the present study was to characterize S100A4‐induced signal transduction mechanisms and to identify S100A4 target genes. We demonstrate that extracellular S100A4 activates the transcription factor NF‐κB in a subset of human cancer cell lines through induction of phosphorylation and subsequent degradation of the NF‐κB inhibitor IκBα. Concomitantly, S100A4 induced a sustained activation of the MAP kinase JNK, whereas no increased activity of the MAP kinases p38 or ERK was observed. Microarray analyses identified 136 genes as being significantly regulated by S100A4 treatment, and potentially interesting S100A4‐induced gene products include IκBα, p53, ephrin‐A1 and optineurin. Increased expression of ephrin‐A1 and optineurin was validated using RT‐PCR, Western blotting and functional assays. Furthermore, S100A4‐stimulated transcription of these target genes was dependent on activation of the NF‐κB pathway. In conclusion, these findings contribute to the understanding of the complex molecular mechanisms responsible for the diverse biological functions of extracellular S100A4, and provide further evidence of how S100A4 may stimulate metastatic progression. © 2008 Wiley‐Liss, Inc.
Chronic rhinosinusitis and risk of lung cancer in the Singapore Chinese Health Study
Authors: Koh Woon‐Puay , Yuan Jian‐Min , Wang Renwei , Seow Adeline , Lee Hin‐Peng , Yu Mimi C.
Published: June 2008

Epidemiologic evidence suggests that chronic inflammatory conditions of the lung may increase lung cancer risk. These chronic conditions, such as chronic obstructive pulmonary disease and asthma, commonly coexist with chronic rhinosinusitis. We prospectively examined if chronic rhinitis or sinusitis was associated with lung cancer risk in the Singapore Chinese Health Study, a population‐based cohort of 63,257 Singapore Chinese, who were aged 45–74 years when recruited between 1993 and 1998. Each subject completed a comprehensive interview on medical conditions, dietary and lifestyle factors at recruitment, and cancer occurrence and survival status were determinedvialinkage to population‐based registries. As of 31 December, 2005, 954 cohort participants had developed lung cancer. Compared with subjects without such history, subjects who reported a history of physician‐diagnosed rhinitis or sinusitis at baseline, whether allergic or nonallergic, had a statistically significant 59% increase in risk of lung cancer (hazard ratio [HR] = 1.59; confidence interval [CI] = 1.06–2.37). This association was significant and stronger in women (HR = 2.32; 95% CI = 1.23–4.39) compared to men, and for the adenocarcinoma cell type (HR = 1.91; 95% CI = 1.07–3.42) compared to other histologies. Overall, a history of asthma, hay fever, allergic dermatitis, food allergy or any other allergic conditions asked in a single question was not related to lung cancer risk (HR = 1.11; 95% CI = 0.90–1.36). Chronic rhinosinusitis may be a marker of pan‐airway inflammation and its association with lung cancer risk provides evidence linking inflammation to lung carcinogenesis, especially among women. © 2008 Wiley‐Liss, Inc.
Gene expression and methylation status of 14‐3‐3σ in human renal carcinoma tissues
Authors: Liang Shufang , Xu Yuhuan , Shen Guobo , Zhao Xinyu , Zhou Jin , Li Xingbin , Gong Fengming , Ling Bo , Fang Li , Huang Canhua , Wei Yuquan
Published: June 2008

Loss of 14‐3‐3σ expression mainly by methylation‐mediated silencing has been reported in several human cancers, but the methylation status of 14‐3‐3σ in human renal carcinoma is rarely studied so far. In this report, 14‐3‐3σ expression was first examined by RT‐PCR and immunohistochemistry, and further we investigated the methylation status by methylation‐specific PCR and the correlation between 14‐3‐3σ expression and its methylation. We found 14‐3‐3σ expression was lost in 27 of 31 renal tissues including 16 renal carcinoma tissues, eight para‐cancerous kidney tissues and seven normal kidney tissues. Among 16 renal carcinoma tissues, 14 cases had complete hypermethylation of 14‐3‐3σ. Eight para‐cancerous kidney tissues were almost completely methylated except one case had both methylation and unmethylation. Among seven normal kidney tissues, five cases had partial methylation, and the other two cases were completely methylated. In addition, 14‐3‐3σ mRNA had weak expression in OS‐RC‐2 cells, but it increased with gradual demethylation after treatment by a demethylation agent, 5‐aza‐2′‐deoxycytidine. In general, 14‐3‐3σ mRNA was mostly unexpressed, and its DNA frequently hypermethylated within 14‐3‐3σ coding region was closely associated with the gene silencing in cancerous and para‐cancerous kidney tissues. 14‐3‐3σ was also frequently methylated and almost silencing in normal kidney tissues. However, the methylation frequency was gradually reinforced with the extent of malignancy from normal to para‐cancerous and cancerous kidney tissues. © 2008 IUBMB IUBMB Life, 60(8): 534–540, 2008
DFT calculations of quadrupolar solid‐state NMR properties: Some examples in solid‐state inorganic chemistry
Authors: Cuny Jerome , Messaoudi Sabri , Alonzo Veronique , Furet Eric , Halet Jean‐François , Le Fur Eric , Ashbrook Sharon E. , Pickard Chris J. , Gautier Regis , Le Polles Laurent
Published: June 2008

This article presents results of first‐principles calculations of quadrupolar parameters measured by solid‐state nuclear magnetic measurement (NMR) spectroscopy. Different computational methods based on density functional theory were used to calculate the quadrupolar parameters. Through a series of illustrations from different areas of solid state inorganic chemistry, it is shown how quadrupolar solid‐state NMR properties can be tackled by a theoretical approach and can yield structural information. © 2008 Wiley Periodicals, Inc. J Comput Chem 2008
First‐principles lattice dynamics calculations of the phase boundary between β‐Si3N4 and γ‐Si3N4 at elevated temperatures and pressures
Authors: Togo Atsushi , Kroll Peter
Published: June 2008

The phase boundary between β‐Si3N4 and γ‐Si3N4 is investigated at high pressure and high temperature using first‐principles lattice dynamics calculations within the quasi‐harmonic approximation. We find a positive slope of the phase boundary, hence, at higher temperatures it requires higher pressures to synthesize the high‐pressure polymorph of silicon nitride. It turns out that the thermal expansion of the spinel‐type γ‐phase is larger than that of the phenacite‐type β‐phase. On the other side, pressure affects more the volume of β‐Si3N4 than of γ‐Si3N4, reflected in the higher bulk modulus of γ‐Si3N4 up to about 40 GPa. The origin of the different temperature behavior of these phases, consequently, is rooted in a larger volume dependence of the zero point energy in γ‐Si3N4 in comparison to β‐Si3N4. © 2008 Wiley Periodicals, Inc. J Comput Chem 2008
Adsorption of single Cu atoms at differently stabilized polar ZnO surfaces: An ab initio study
Authors: Hegemann Ilka , Schwaebe Andreas , Fink Karin
Published: June 2008

In this study, the adsorption of a single Cu atom on the polar ZnO(0001) and ZnO(000) surfaces was investigated by means of highly accurate wave function based ab initio methods. Different modifications of the polar surfaces were investigated: unstabilized surfaces, surfaces with hydrogen and OH overlayers, and defectious surfaces. Cu is strongly bound at the unstabilized surfaces by a charge transfer mechanism which induces a stabilization of the surface. At regular adsorption sites of stabilized surfaces the binding energies are much smaller. At oxygen defects, the Cu electron is transferred to the defect and a Cu+ ion sits on top of the defect. At the Zn terminated surface the Cu moves into the Zn defects. © 2008 Wiley Periodicals, Inc. J Comput Chem 2008
A new animal model for bone atrophic nonunion: Fixation by external fixator
Authors: Kaspar Katharina , Matziolis Georg , Strube Patrick , Sentürk Ufuk , Dormann Svenja , Bail Hermann J. , Duda Georg N.
Published: June 2008

A new small animal model of bone atrophic nonunion was established for investigating the process of bone regeneration by performing cauterization of the periosteum, removal of the local bone marrow, and stabilization with external fixation. The model allows the creation of an atrophic nonunion without the need for a critical size defect. Furthermore, it provides reproducible, well‐defined mechanical conditions and minimized physical interference of the implant with the biological processes in the healing zone. Eighty adult Sprague‐Dawley rats received an osteotomy of the left femur, stabilized with an external fixator. In half of the animals, the periosteum proximal and distal to the osteotomy was destroyed by cauterization and the adjacent bone marrow was removed (nonunion group). At 2 and 8 weeks after surgery, radiological, biomechanical, histological, and histomorphometrical analyses showed a typical physiological healing in the control group, while the nonunion group was characterized by resorption of the bone ends with some callus formation distant to the osteotomy. At both time points, the callus was composed of significantly less bone and significantly more connective tissue (p < 0.001). In addition, the torsional strength of the osteotomized femur was significantly less in the nonunion group than in the control group, which was comparable to that of the intact femur (p < 0.001). In conclusion, the present model allows the induction of an atrophic nonunion without the need of a critical size defect. It is reproducible, provides standardized biomechanical conditions, and allows minimized interaction of the implant with the healing zone. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res