bluuebunny/crossref_metadata_2025 huggingface dataset:
The Thiol:Disulfide Oxidoreductase DsbB Mediates the Oxidizing Effects of the Toxic Metalloid Tellurite (TeO32−) on the Plasma Membrane Redox System of the Facultative PhototrophRhodobacter capsulatus
Authors: Borsetti Francesca , Francia Francesco , Turner Raymond J. , Zannoni Davide
Published: November 2006

The highly toxic oxyanion tellurite (TeO32−) is a well known pro-oxidant in mammalian and bacterial cells. This work examines the effects of tellurite on the redox state of the electron transport chain of the facultative phototrophRhodobacter capsulatus, in relation to the role of the thiol:disulfide oxidoreductase DsbB. Under steady-state respiration, the addition of tellurite (2.5 mM) to membrane fragments generated an extrareduction of the cytochrome pool (c- andb-type hemes); further, in plasma membranes exposed to tellurite (0.25 to 2.5 mM) and subjected to a series of flashes of light, the rate of the QH2:cytochromec(Cytc) oxidoreductase activity was enhanced. The effect of tellurite was blocked by the antibiotics antimycin A and/or myxothiazol, specific inhibitors of the QH2:Cytcoxidoreductase, and, most interestingly, the membrane-associated thiol:disulfide oxidoreductase DsbB was required to mediate the redox unbalance produced by the oxyanion. Indeed, this phenomenon was absent fromR. capsulatusMD22, a DsbB-deficient mutant, whereas the tellurite effect was present in membranes from MD22/pDsbBWT, in which the mutant gene was complemented to regain the wild-type DsbB phenotype. These findings were taken as evidence that the membrane-bound thiol:disulfide oxidoreductase DsbB acts as an “electron conduit” between the hydrophilic metalloid and the lipid-embedded Q pool, so that in habitats contaminated with subinhibitory amounts of TeIV, the metalloid is likely to function as a disposal for the excess reducing power at the Q-pool level of facultative phototrophic bacteria.
Borrelia burgdorferi
Alters Its Gene Expression and Antigenic Profile in Response to CO
2
Levels
Authors: Hyde Jenny A. , Trzeciakowski Jerome P. , Skare Jonathan T.
Published: November 2006

The etiologic agent of Lyme disease,
Borrelia burgdorferi
, must adapt to the distinct environments of its arthropod vector and mammalian host during its complex life cycle.
B. burgdorferi
alters gene expression and protein synthesis in response to temperature, pH, and other uncharacterized environmental factors. The hypothesis tested in this study is that dissolved gases, including CO
2
, serve as a signal for
B. burgdorferi
to alter protein production and gene expression. In this study we focused on characterization of in vitro anaerobic (5% CO
2
, 3% H
2
, 0.087 ppm O
2
) and microaerophilic (1% CO
2
, 3.48 ppm O
2
) growth conditions and how they modulate protein synthesis and gene expression in
B. burgdorferi
. Higher levels of several immunoreactive proteins, including BosR, NapA, DbpA, OspC, BBK32, and RpoS, were synthesized under anaerobic conditions. Previous studies demonstrated that lower levels of NapA were produced when microaerophilic cultures were purged with nitrogen gas to displace oxygen and CO
2
. In this study we identified CO
2
as a factor contributing to the observed change in NapA synthesis. Specifically, a reduction in the level of dissolved CO
2
, independent of O
2
levels, resulted in reduced NapA synthesis. BosR, DbpA, OspC, and RpoS synthesis was also decreased with the displacement of CO
2
. Quantitative reverse transcription-PCR indicated that the levels of the
dbpA
,
ospC
, and BBK32 transcripts are increased in the presence of CO
2
, indicating that these putative borrelial virulence determinants are regulated at the transcriptional level. Thus, dissolved CO
2
may be an additional cue for borrelial host adaptation and gene regulation.
Respiratory Nitrate Ammonification byShewanella oneidensisMR-1
Authors: Cruz-García Claribel , Murray Alison E. , Klappenbach Joel A. , Stewart Valley , Tiedje James M.
Published: November 2006

Anaerobic cultures ofShewanella oneidensisMR-1 grown with nitrate as the sole electron acceptor exhibited sequential reduction of nitrate to nitrite and then to ammonium. Little dinitrogen and nitrous oxide were detected, and no growth occurred on nitrous oxide. A mutant with thenapAgene encoding periplasmic nitrate reductase deleted could not respire or assimilate nitrate and did not express nitrate reductase activity, confirming that the NapA enzyme is the sole nitrate reductase. Hence,S. oneidensisMR-1 conducts respiratory nitrate ammonification, also termed dissimilatory nitrate reduction to ammonium, but not respiratory denitrification.
Role of Gne and GalE in the Virulence of
Aeromonas hydrophila
Serotype O34
Authors: Canals Rocío , Jiménez Natalia , Vilches Silvia , Regué Miguel , Merino Susana , Tomás Juan M.
Published: November 2006

The mesophilic
Aeromonas hydrophila
AH-3 (serotype O34) strain shows two different UDP-hexose epimerases in its genome: GalE (EC 3.1.5.2) and Gne (EC 3.1.5.7). Similar homologues were detected in the different mesophilic
Aeromonas
strains tested. GalE shows only UDP-galactose 4-epimerase activity, while Gne is able to perform a dual activity (mainly UDP-
N
-acetyl galactosamine 4-epimerase and also UDP-galactose 4-epimerase). We studied the activities in vitro of both epimerases and also in vivo through the lipopolysaccharide (LPS) structure of
A. hydrophila gne
mutants,
A. hydrophila galE
mutants,
A. hydrophila galE-gne
double mutants, and independently complemented mutants with both genes. Furthermore, the enzymatic activity in vivo, which renders different LPS structures on the mentioned
A. hydrophila
mutant strains or the complemented mutants, allowed us to confirm a clear relationship between the virulence of these strains and the presence/absence of the O34 antigen LPS.
The Complete Genome Sequence of
Roseobacter denitrificans
Reveals a Mixotrophic Rather than Photosynthetic Metabolism
Authors: Swingley Wesley D. , Sadekar Sumedha , Mastrian Stephen D. , Matthies Heather J. , Hao Jicheng , Ramos Hector , Acharya Chaitanya R. , Conrad Amber L. , Taylor Heather L. , Dejesa Liza C. , Shah Maulik K. , O'Huallachain Maeve E. , Lince Michael T. , Blankenship Robert E. , Beatty J. Thomas , Touchman Jeffrey W.
Published: November 2006

Purple aerobic anoxygenic phototrophs (AAPs) are the only organisms known to capture light energy to enhance growth only in the presence of oxygen but do not produce oxygen. The highly adaptive AAPs compose more than 10% of the microbial community in some euphotic upper ocean waters and are potentially major contributors to the fixation of the greenhouse gas CO
2
. We present the complete genomic sequence and feature analysis of the AAP
Roseobacter denitrificans
, which reveal clues to its physiology. The genome lacks genes that code for known photosynthetic carbon fixation pathways, and most notably missing are genes for the Calvin cycle enzymes ribulose bisphosphate carboxylase (RuBisCO) and phosphoribulokinase. Phylogenetic evidence implies that this absence could be due to a gene loss from a RuBisCO-containing α-proteobacterial ancestor. We describe the potential importance of mixotrophic rather than autotrophic CO
2
fixation pathways in these organisms and suggest that these pathways function to fix CO
2
for the formation of cellular components but do not permit autotrophic growth. While some genes that code for the redox-dependent regulation of photosynthetic machinery are present, many light sensors and transcriptional regulatory motifs found in purple photosynthetic bacteria are absent.
Characterization of Two Sets of Subpolar Flagella in
Bradyrhizobium japonicum
Authors: Kanbe Masaomi , Yagasaki Jin , Zehner Susanne , Göttfert Michael , Aizawa Shin-Ichi
Published: November 2006

Bradyrhizobium japonicum
is one of the soil bacteria that form nodules on soybean roots. The cell has two sets of flagellar systems, one thick flagellum and a few thin flagella, uniquely growing at subpolar positions. The thick flagellum appears to be semicoiled in morphology, and the thin flagella were in a tight-curly form as observed by dark-field microscopy. Flagellin genes were identified from the amino acid sequence of each flagellin. Flagellar genes for the thick flagellum are scattered into several clusters on the genome, while those genes for the thin flagellum are compactly organized in one cluster. Both types of flagella are powered by proton-driven motors. The swimming propulsion is supplied mainly by the thick flagellum.
B. japonicum
flagellar systems resemble the polar-lateral flagellar systems of
Vibrio
species but differ in several aspects.
Contribution of Invariant Residues to the Function of Rgg Family Transcription Regulators
Authors: Loughman Jennifer A. , Caparon Michael G.
Published: November 2006

The Rgg family of transcription regulators is widely distributed among gram-positive bacteria, yet how these proteins control transcription is poorly understood. UsingStreptococcus pyogenesRopB as a model, we demonstrated that residues invariant among Rgg-like regulators are critical for function and obtained evidence for a mechanism involving protein complex formation.
Specific Interaction between the Initiator Protein (Rep) and Origin of Plasmid ColE2-P9
Authors: Han M. , Yagura M. , Itoh T.
Published: November 2006

The replication initiator protein (Rep) of plasmid ColE2-P9 (ColE2) is multifunctional. We are interested in how Rep binds to the origin (Ori) to perform various functions. We used the wild type and variants of Rep to study the Rep-Ori interaction by both in vitro and in vivo approaches, including biochemical analyses of protein-DNA interactions and an in vivo replication assay. We identified three regions (I, II, and III) of Rep, located in the C-terminal half, and three corresponding binding sites (I, II, and III) in Ori which are important for Rep-Ori interaction. We showed that region I, containing a putative helix-turn-helix motif, is necessary and sufficient for specific Ori recognition, interacting with site I of the origin DNA from the major groove. Region II interacts with site II of the origin DNA, from the adjacent minor groove in the left half of Ori, and region III interacts with site III, next to the template sequence for primer synthesis, which is one and one-half turn apart from site I on the opposite surface of the origin DNA. A putative linker region located between the two DNA binding domains (regions II and III) was identified, which might provide Rep an extended conformation suitable for binding to the two separate sites in Ori. Based on the results presented in this paper, we propose a model for Rep-Ori interaction in which Rep binds to Ori as a monomer.
Molecular Evolution of Typical EnteropathogenicEscherichia coli: Clonal Analysis by Multilocus Sequence Typing and Virulence Gene Allelic Profiling
Authors: Lacher David W. , Steinsland Hans , Blank T. Eric , Donnenberg Michael S. , Whittam Thomas S.
Published: November 2006

EnteropathogenicEscherichia coli(EPEC) infections are a leading cause of infantile diarrhea in developing nations. Typical EPEC isolates are differentiated from other types of pathogenicE. coliby two distinctive phenotypes, attaching effacement and localized adherence. The genes specifying these phenotypes are found on the locus of enterocyte effacement (LEE) and the EPEC adherence factor (EAF) plasmid. To describe how typical EPEC has evolved, we characterized a diverse collection of strains by multilocus sequence typing (MLST) and performed restriction fragment length polymorphism (RFLP) analysis of three virulence genes (eae,bfpA, andperA) to assess allelic variation. Among 129 strains representing 20 O-serogroups, 21 clonal genotypes were identified using MLST. RFLP analysis resolved nineeae, ninebfpA, and fourperAalleles. EachbfpAallele was associated with only oneperAallele class, suggesting that recombination has not played a large role in shuffling thebfpAandperAloci between separate EAF plasmids. The distribution ofeaealleles among typical EPEC strains is more concordant with the clonal relationships than the distribution of the EAF plasmid types. These results provide further support for the hypothesis that the EPEC pathotype has evolved multiple times withinE. colithrough separate acquisitions of the LEE island and EAF plasmid.
Reporting of ethnicity in research on chronic disease: update
Authors: O'Loughlin J , Dugas E , Maximova K , Kishchuk N
Published: November 2006

This paper examines the inclusion of ethnicity and race as variables in current, leading edge research on chronic disease and its risk factors. Of 100 randomly selected original research articles published in high-impact journals in 2005, 85% did not report either a definition of ethnicity or its conceptualisation in terms of theoretical reasoning, and 98% did not report an actual measurement item. Ethnicity and race remain non-standardised and largely underdescribed variables in research on chronic disease. This represents an important loss of opportunity to articulate and test hypotheses about the mechanisms underlying ethnic group differences in chronic disease.
Post lumbar puncture headache: diagnosis and management
Authors: Ahmed S V , Jayawarna C , Jude E
Published: November 2006

Lumbar puncture is a frequently performed procedure in medical emergencies and anaesthesia. Headache after lumbar puncture is a common occurrence (32%) and carries a considerable morbidity, with symptoms lasting for several days, at times severe enough to immobilise the patient. If untreated, it can result in serious complications such as subdural haematoma and seizures, which could be fatal. Certain factors contribute to the development of headache after lumbar puncture. If these factors are taken into consideration, the incidence of headache could be markedly reduced. It is therefore important that the doctors are aware of the methods available for reducing the incidence of headaches after lumbar puncture. On the other hand, there are several misconceptions that are thought to decrease the incidence of headaches with no scientific basis. This article reviews the scientific literature and highlights the practical issues involved in the diagnosis and management of headaches after lumbar puncture, including the epidural blood patch treatment.
Complications of coeliac disease: are all patients at risk?
Authors: Goddard C J R , Gillett H R
Published: November 2006

Coeliac disease is a common condition that is increasingly being recognised as a result of the development of sensitive and specific serology. The diagnosis of coeliac disease and its subsequent treatment with a gluten-free diet have implications for the patient, not just for symptom control but also for the possible effect on quality of life and risk of complications. Whether the mode of presentation of coeliac disease has an effect on survival or risk of complication is yet unclear. This article reviews the available evidence regarding these issues.
Sexually transmitted proctitis
Authors: Hamlyn E , Taylor C
Published: November 2006

Sexually transmitted infections such as chlamydia, gonorrhoea, herpes simplex virus and syphilis commonly present with rectal symptoms. Recent outbreaks of lymphogranuloma venereum among homosexual men throughout Europe highlight the need to consider sexually transmitted infections in the differential diagnosis of proctitis. This article examines the causative organisms, clinical features, diagnosis and treatment of sexually transmitted proctitis.
CROWELL'S DERIVED GROUP AND TWISTED POLYNOMIALS
Authors: SILVER DANIEL S. , WILLIAMS SUSAN G.
Published: November 2006

The derived group of a permutation representation, introduced by Crowell, unites many notions of knot theory. We survey Crowell's construction, and offer new applications.

The twisted Alexander group of a knot is defined. Using it, we obtain twisted Alexander polynomials. Also, we extend a well-known theorem of Neuwirth and Stallings giving necessary and sufficient conditions for a knot to be fibered.

Virtual Alexander polynomials provide obstructions for a virtual knot that must vanish if the knot has a diagram with an Alexander numbering. The extended group of a virtual knot is defined, and using it a more sensitive obstruction is obtained.
DESIGN AS AN ELEMENT OF INNOVATION: EVALUATING DESIGN EMPHASIS IN TECHNOLOGY-BASED FIRMS
Authors: CANDI MARINA
Published: November 2006

Design is increasingly gaining recognition as a fruitful means to improve business performance. Technology-based firms are an important source of innovation, and therefore it is important to develop a means to study the relationship between technology-based firms' emphasis on design as an element of innovation and their performance. This article develops a model for evaluating technology-based firms' design emphasis. The model is based on a synthesis approach to studying innovation in both services and manufacturing and a three-dimensional definition of design.

The application of the model is demonstrated using a set of new technology-based firms. The empirical study confirms the appropriateness of using the synthesis approach for studying design as an element of innovation in technology-based firms. The application of the model provides a classification which can be used as a basis for studying the relationship between design emphasis and performance.
TOWARDS A SYSTEM OF PERFORMANCE MEASURES FOR RESEARCH ACTIVITIES: NIKEM RESEARCH CASE STUDY
Authors: FRATTINI FEDERICO , LAZZAROTTI VALENTINA , MANZINI RAFFAELLA
Published: November 2006

Although theoretical approaches to research and development (R&D) performance measurement are widespread, empirical investigations into the application of these theories are far less diffused. Therefore, we started a research project aimed at studying the R&D performance measurement practices adopted by Italian technology-intensive firms. This paper discusses the earliest empirical results of the project; it deeply investigates the experience of an Italian contract research organisation in designing a system of performance measures for its research activities.

The studied case is interesting for the following reasons: (i) it witnesses the increased interest by technology-intensive companies towards R&D performance measurement; (ii) it enlightens the lack of consolidated practices capable of guiding the design of an appropriate performance measurement system; (iii) it elaborates a practical framework that can help fill this gap. In fact, a systematic approach for linking different contextual variables (i.e. the company's strategy, the type of R&D activity undertaken, the purpose of the measurement and the R&D unit's organisational structure) to the critical design choices (i.e. the choice of the performance indicators and the structure of the system) is suggested.
Single-Molecule Probing of Adsorption and Diffusion on Silica Surfaces
Authors: Wirth Mary J. , Legg Michael A.
Published: November 2006

Single-molecule spectroscopy has emerged as a valuable tool in probing kinetics and dynamic equilibria in adsorption because advances in instrumentation and technology have enabled researchers to obtain high signal-to-noise ratios for common dyes at room temperature. Single-molecule spectroscopy was applied to the study of an important problem in chromatography: peak broadening and asymmetry in the chromatograms of pharmaceuticals, peptides, and proteins. Using DiI, a cationic dye that exhibits the same problematic chromatographic behavior, investigators showed that the adsorption sites that cause chromatographic problems are located at defects on the silica crystal surface.
Ouabain protects rat hearts against ischemia-reperfusion injury via pathway involving src kinase, mitoKATP, and ROS
Authors: Pasdois Philippe , Quinlan Casey L. , Rissa Abraham , Tariosse Liliane , Vinassa Béatrice , Costa Alexandre D. T. , Pierre Sandrine V. , Dos Santos Pierre , Garlid Keith D.
Published: November 2006

We showed recently that mitochondrial ATP-dependent K+channel (mitoKATP) opening is required for the inotropic response to ouabain. Because mitoKATPopening is also required for most forms of cardioprotection, we investigated whether exposure to ouabain was cardioprotective. We also began to map the signaling pathways linking ouabain binding to Na+-K+-ATPase with the opening of mitoKATP. In Langendorff-perfused rat hearts, 10–80 μM ouabain given before the onset of ischemia resulted in cardioprotection against ischemia-reperfusion injury, as documented by an improved recovery of contractile function and a reduction of infarct size. In skinned cardiac fibers, a ouabain-induced protection of mitochondrial outer membrane integrity, adenine nucleotide compartmentation, and energy transfer efficiency was evidenced by a decreased release of cytochrome c and preserved half-saturation constant of respiration for ADP and adenine nucleotide translocase-mitochondrial creatine kinase coupling, respectively. Ouabain-induced positive inotropy was dose dependent over the range studied, whereas ouabain-induced cardioprotection was maximal at the lowest dose tested. Compared with bradykinin (BK)-induced preconditioning, ouabain was equally efficient. However, the two ligands clearly diverge in the intracellular steps leading to mitoKATPopening from their respective receptors. Thus BK-induced cardioprotection was blocked by inhibitors of cGMP-dependent protein kinase (PKG) or guanylyl cyclase (GC), whereas ouabain-induced protection was not blocked by either agent. Interestingly, however, ouabain-induced inotropy appears to require PKG and GC. Thus 5-hydroxydecanoate (a selective mitoKATPinhibitor), N-(2-mercaptopropionyl)glycine (MPG; a reactive oxygen species scavenger), ODQ (a GC inhibitor), PP2 (a src kinase inhibitor), and KT-5823 (a PKG inhibitor) abolished preconditioning by BK and blocked the inotropic response to ouabain. However, only PP2, 5-HD, and MPG blocked ouabain-induced cardioprotection.
Force-length relations in isolated intact cardiomyocytes subjected to dynamic changes in mechanical load
Authors: Iribe Gentaro , Helmes Michiel , Kohl Peter
Published: November 2006

We developed a dynamic force-length (FL) control system for single intact cardiomyocytes that uses a pair of compliant, computer-controlled, and piezo translator (PZT)-positioned carbon fibers (CF). CF are attached to opposite cell ends to afford dynamic and bidirectional control of the cell's mechanical environment. PZT and CF tip positions, as well as sarcomere length (SL), are simultaneously monitored in real time, and passive/active forces are calculated from CF bending. Cell force and length were dynamically adjusted by corresponding changes in PZT position, to achieve isometric, isotonic, or work-loop style contractions. Functionality of the technique was assessed by studying FL behavior of guinea pig intact cardiomyocytes. End-diastolic and end-systolic FL relations, obtained with varying preload and/or afterloads, were near linear, independent of the mode of contraction, and overlapping for the range of end-diastolic SLs tested (1.85–2.05 μm). Instantaneous elastance curves, obtained from FL relation curves, showed an afterload-dependent decrease in time to peak elastance and slowed relaxation with both increased preload and afterload. The ability of the present system to independently and dynamically control preload, afterload, and transition between end-diastolic and end-systolic FL coordinates provides a valuable extension to the range of tools available for the study of single cardiomyocyte mechanics, to foster its interrelation with whole heart pathophysiology.
Steeper restitution slopes across right ventricular endocardium in patients with cardiomyopathy at high risk of ventricular arrhythmias
Authors: Selvaraj Raja J. , Picton Peter , Nanthakumar Kumaraswamy , Chauhan Vijay S.
Published: November 2006

Steep action potential duration (APD) restitution slopes (>1) and spatial APD restitution heterogeneity provide the substrate for ventricular fibrillation in computational models and experimental studies. Their relationship to ventricular arrhythmia vulnerability in human cardiomyopathy has not been defined. Patients with cardiomyopathy [left ventricular (LV) ejection fraction <40%] and no history of ventricular arrhythmias underwent risk stratification with programmed electrical stimulation or T wave alternans (TWA). Low-risk patients ( n = 10) had no inducible ventricular tachycardia (VT) or negative TWA, while high-risk patients ( n = 8) had inducible VT or positive TWA. Activation recovery interval (ARI) restitution slopes were measured simultaneously from 10 right ventricular (RV) endocardial sites during an S1-S2 pacing protocol. ARI restitution slope heterogeneity was defined as the coefficient of variation of slopes. Mean ARI restitution slope was significantly steeper in the high-risk group compared with the low-risk group [1.16 (SD 0.31) vs. 0.59 (SD 0.19), P = 0.0002]. The proportion of endocardial recording sites with a slope >1 was significantly larger in the high-risk patients [47% (SD 35) vs. 13% (SD 21), P = 0.022]. Spatial heterogeneity of ARI restitution slopes was similar between the two groups [29% (SD 16) vs. 39% (SD 34), P = 0.48]. There was an inverse linear relationship between the ARI restitution slope and the minimum diastolic interval ( P < 0.001). In cardiomyopathic patients at high risk of ventricular arrhythmias, ARI restitution slopes along the RV endocardium are steeper, but restitution slope heterogeneity is similar compared with those at low risk. Steeper ARI restitution slopes may increase the propensity for ventricular arrhythmias in patients with impaired left ventricular function.
Thiol oxidation causes pulmonary vasodilation by activating K+ channels and inhibiting store-operated Ca2+ channels
Authors: Schach Christian , Xu Minlin , Platoshyn Oleksandr , Keller Steve H. , Yuan Jason X.-J.
Published: November 2006

Cellular redox change regulates pulmonary vascular tone by affecting function of membrane and cytoplasmic proteins, enzymes, and second messengers. This study was designed to test the hypothesis that functional modulation of ion channels by thiol oxidation contributes to regulation of excitation-contraction coupling in isolated pulmonary artery (PA) rings. Acute treatment with the thiol oxidant diamide produced a dose-dependent relaxation in PA rings; the IC50 was 335 and 58 μM for 40 mM K+- and 2 μM phenylephrine-induced PA contraction, respectively. The diamide-mediated pulmonary vasodilation was affected by neither functional removal of endothelium nor 8-bromoguanosine-3′-5′-cyclic monophosphate (50 μM) and HA-1004 (30 μM). A rise in extracellular K+ concentration (from 20 to 80 mM) attenuated the thiol oxidant-induced PA relaxation. Passive store depletion by cyclopiazonic acid (50 μM) and active store depletion by phenylephrine (in the absence of external Ca2+) both induced PA contraction due to capacitative Ca2+ entry. Thiol oxidation by diamide significantly attenuated capacitative Ca2+ entry-induced PA contraction due to active and passive store depletion. The PA rings isolated from left and right PA branches appeared to respond differently to store depletion. Although the active tension induced by passive store depletion was comparable, the active tension induced by active store depletion was 3.5-fold greater in right branches than in left branches. These data indicate that thiol oxidation causes pulmonary vasodilation by activating K+ channels and inhibiting store-operated Ca2+ channels, which subsequently attenuate Ca2+ influx and decrease cytosolic free Ca2+ concentration in pulmonary artery smooth muscle cells. The mechanisms involved in thiol oxidation-mediated pulmonary vasodilation or activation of K+ channels and inhibition of store-operated Ca2+ channels appear to be independent of functional endothelium and of the cGMP-dependent protein kinase pathway.
Discovering the mechanism of capacitative calcium entry
Authors: Rosado Juan A.
Published: November 2006

This essay examines the historical significance of an APS classic paper that is freely available online:

Kwan CY, Takemura H, Obie JF, Thastrup O, and Putney JW Jr.

Effects of MeCh, thapsigargin, and La3+ on plasmalemmal and intracellular Ca2+ transport in lacrimal acinar cells. Am J Physiol Cell Physiol 258: C1006–C1015, 1990. ( http://ajpcell.physiology.org/cgi/reprint/258/6/C1006 )
Activation of Inward Rectifier Potassium Channels Accelerates Atrial Fibrillation in Humans
Authors: Atienza Felipe , Almendral Jesús , Moreno Javier , Vaidyanathan Ravi , Talkachou Arkazdi , Kalifa Jérôme , Arenal Angel , Villacastín Julian P. , Torrecilla Esteban G. , Sánchez Ana , Ploutz-Snyder Robert , Jalife José , Berenfeld Omer
Published: November 2006

Background—

It is unclear whether atrial fibrillation (AF) drivers in humans are focal or reentrant. To test the hypothesis that functional reentry is involved in human AF maintenance, we determined the effects of adenosine infusion on local dominant frequency (DF) at different atrial sites. By increasing inward rectifier potassium channel conductance, adenosine would increase DF of reentrant drivers but decrease it in the case of a focal mechanism.

Methods and Results—

Thirty-three patients were studied during AF (21 paroxysmal, 12 persistent) using recordings from each pulmonary vein–left atrial junction (PV-LAJ), high right atrium, and coronary sinus. DFs were determined during baseline and peak adenosine effect. In paroxysmal AF, adenosine increased maximal DF at each region compared with baseline (PV-LAJ, 8.03±2.2 versus 5.7±0.8; high right atrium, 7±2.2 versus 5.4±0.7; coronary sinus, 6.6±1.1 versus 5.3±0.7 Hz;
P
=0.001) and increased the left-to-right DF gradient (
P
=0.007). In contrast, in persistent AF, adenosine increased DF only in the high right atrium (8.33±1.1 versus 6.8±1.2 Hz;
P
=0.004). In 4 paroxysmal AF patients, real-time DF mapping of the left atrium identified the highest DF sites near the PV-LAJ, where adenosine induced an increase in DF (6.7±0.29 versus 4.96±0.26 Hz;
P
=0.008). Finally, simulations demonstrate that the frequency of reentrant drivers accelerates proportionally to the adenosine-modulated inward rectifier potassium current.

Conclusions—

Adenosine accelerates drivers and increases frequency differently in paroxysmal compared with persistent human AF. The results strongly suggest that AF is maintained by reentrant sources, most likely located at the PV-LAJ in paroxysmal AF, whereas non-PV locations are more likely in persistent AF.
Innate Defense Mechanism Against Virus Infection Within the Cardiac Myocyte Requiring gp130-STAT3 Signaling
Authors: Yajima Toshitaka , Yasukawa Hideo , Jeon Eun-Seok , Xiong Dingding , Dorner Andrea , Iwatate Mitsuo , Nara Miwako , Zhou Hanbing , Summers-Torres Daphne , Hoshijima Masahiko , Chien Kenneth R. , Yoshimura Akihiko , Knowlton Kirk U.
Published: November 2006

Background—

Little is known about innate immune mechanisms within the cardiac myocyte that determine susceptibility to enterovirus infection, an important cause of myocarditis and subsequent heart failure. Although interferon (IFN) generally plays a key role in innate immunity, ablation of IFN receptors has little or no effect on acute coxsackievirus B3 infection in the heart. Interestingly, gp130-cytokine–mediated stimulation of neonatal ventricular myocytes has a cytoprotective effect against virus infection in culture that can be inhibited by suppressors of cytokine signaling (SOCS)-3, a physiological inhibitor of gp130 signaling that does not affect IFN signaling. Therefore, we hypothesized that inhibition of gp130 signaling by SOCS3 would change cardiac myocyte susceptibility to virus infection without affecting IFN signaling.

Methods and Results—

We generated cardiac-specific SOCS3 transgenic mice. Despite an intact IFN-mediated antiviral response in adult transgenic myocytes, there was a marked increase in susceptibility to viral infection in the SOCS3 transgenic mouse hearts. This indicated the presence of IFN-independent innate defense mechanisms within the cardiac myocyte. Subsequently, we demonstrated that cardiac-specific gp130-knockout mice also had increased susceptibility to viral infection. Furthermore, we demonstrated that the gp130-mediated increase in survival of infected myocytes occurred through a signal transducers and activators of transcription-3–dependent mechanism that did not affect viral replication. This was accompanied by a persistent expression of full-length dystrophin after coxsackievirus B3 infection. In addition, we found that both SOCS3 transgenic and gp130-deficient mice had a decrease in α-sarcoglycan.

Conclusions—

SOCS3-mediated regulation of gp130 signaling can affect susceptibility to viral infection in the heart. Increased cardiac cell survival through gp130–signal transducers and activators of transcription-3 signaling appears to play an important role in preserving nondividing cardiac myocytes until specific immune responses begin to clear the virus.
Dementia and the Law
Authors: Gevers Sjef
Published: November 2006

The care for patients with dementia raises many legal (and ethical) issues. This article explores some of the more important topics, i.e. (early) diagnosis of the disease, the availability and provision of care, treatment and non treatment decisions, and medical research with dementia patients.
Bio-Inspired Cell Concentration and Deformability Monitoring Chips
Authors: Cho Young-Ho , Youn Sechan , Lee Dong Woo
Published: November 2006

The paper presents a couple of biofluidic devices, whose functions are inspired from biological cell concentration and deformability monitoring functions. The cell concentration monitoring chip is inspired from RBC control mechanism in kidney, performing cell concentration monitoring
functions. The cell deformability chip, inspired from selective RBC destruction mechanism in spleen, performs mechanical cell deformability monitoring functions. The structures and principles of the bio-inspired chips are presented and compared with those of the biological organs. The unique
features and performance characteristics of the bio-inspired chips are analyzed and verified from experimental study. The bio-inspired cell concentration monitoring chips perform flow-rate insensitive concentration measurement, while the bio-inspired cell deformability monitoring chips achieve
size-independent cell deformability measurement. Common advantages of the bio-inspired chips include simple structures, digital signals and high integrability, thus making them suitable for use in integrated digital biomedical systems.
Atomistic Simulation of Boron Diffusion with Charged Defects and Diffusivity in Strained Si/SiGe
Authors: Kim Young-Kyu , Yoon Kwan-Sun , Kim Joong-Sik , Won Taeyoung
Published: November 2006

We discuss the boron diffusion in a biaxial tensile strained {001} Si and SiGe layer with kinetic Monte Carlo (KMC) method. We created a strain in silicon by adding a germanium mole fraction in silicon in order to perform a theoretical analysis. The generation of a strain in silicon
influences in the diffusivity as well as the penetration profile during the implantation. The strain energy for the charged defects has been calculated from the ab-initio calculation while the diffusivity of boron was extracted from the Arrhenius formula. Hereby, the influence of the
germanium content on the dopant diffusivity was estimated. Our KMC study revealed that the diffusion of the B atoms was retarded with increasing Germanium mole fraction in a strained silicon layer. Furthermore, we derived a functional dependence of the in-plane strain as well as the out-of-plane
strain on the germanium mole fraction, which lies in the distribution of equivalent stresses along the Si/SiGe interface.
Combination of Differential Interference Contrast with Prism-Type Total Internal Fluorescence Microscope for Direct Observation of Polyamidoamine Dendrimer Nanoparticle as a Gene Delivery in Living Human Cells
Authors: Lee Seungah , Choi Joon Sig , Kang Seong Ho
Published: November 2006

A combined system of differential interference contrast (DIC) and total internal reflection fluorescence microscope (TIRFM) with a transmitted all-side polished dove prism was used for the direct monitoring of polyamidoamine (PAMAM) dendrimer nanoparticles as a gene delivery in living
human embryonic kidney 293 (HEK 293) cells. The PAMAM dendrimer conjugated with fluorescein isothiocyanate (FITC) was used to form a fluorescent nanoparticle with the plasmid DNA (complexes) in order to directly monitor the entry of the complexes inside living cells. The DIC image provided
precise information of the living HEK 293 cellular structures. Without moving the cell, the TIRFM images of the PAMAM nanoparticle-DNA complexes on the all-side polished dove prism provided precise information on the distance between the cell membrane and the complexes (<200 nm) as well
as the real-time localization of the individual complexes in the cells. The complexes were observed in cytosol within 4 h after incubating the cells with the complexes in Dulbecco's modified eagle's medium. The localization data of the complexes inside the cell obtained by TIRFM were reconfirmed
using 3D confocal microscopy images of the complexes at the subcellular localization. These results suggest that the combined system of DIC and all-side polished dove prism-type TIRFM is a powerful tool for the direct real-time monitoring of the internalization and subcellular localization
of nanoparticles carrying genes through a nonviral approach for gene therapy.
Equivalent Circuit Model of Semiconductor Nanowire Diode by SPICE
Authors: Lee Sehan , Yu Yunseop , Hwang Sungwoo , Ahn Doyeol
Published: November 2006

An equivalent circuit model of nanowire diodes is introduced. Because nanowire diodes inevitably involve a metal-semiconductor-metal structure, they consist of two metal-semiconductor contacts and one resistor in between these contacts. Our equivalent circuit consists of two Schottky
diodes and one resistor. The current through the reverse-biased Schottky diode is calculated from the thermionic field emission (TFE) theory and that of the forward-biased Schottky diode is obtained from the classical thermionic emission (TE) equation. Our model is integrated into the conventional
circuit simulator SPICE by a sub-circuit with TFE and TE routines. The results simulated with our model by SPICE are in good agreement with various, previously reported experimental results.
Behavior Characteristics of Nano-Stage According to Hinge Structure
Authors: Oh Hyun-Seong , Lee Sung-Jun , Kim Yong-Woo , Lee Deug-Woo
Published: November 2006

Nano-stages are used in many ultra-precision systems, such as scanning probe microscope (SPM), optical fiber aligners, ultra-precision cutting, measuring and optical systems. Generally, ultra-precision machining and measuring are achieved using a nano-scale motion stage actuated using
Piezo-electric actuators (PZT), and the importance of and demands for the motion stage increase with the need to improve system performance and accuracy. However, it is difficult to find solutions because the performance and characteristics of nano-scale motion stages are determined by various
factors, such as the hinge structure, actuator, and method of system control. This paper focuses on improving of leafspring and planar joint hinges, and suggests a composite joint hinge stage.
Neutron Scintillators of Transparent Silica Xerogel Monolith via a Sealed Container System and π–π Interactions
Authors: Im Hee-Jung , Lee Byunghwan , Brown Suree S. , Dai Sheng
Published: November 2006

Transparent crack-free lithiated sol–gel scintillating monoliths were developed by taking advantage of a sealed container system for a syneresis and the π–π interactions between sol–gel components and organic fluors to yield a better homogeneity
and scintillating efficiency. The transparency of the resulting materials indicates that the new scintillating material composites are mesoscopically dispersed. The silica monolith can be prepared without cladding the monolith with an engineering plastic such as a poly(ether ether ketone)
(PEEK) or a liquid mounting medium. A successful detection of neutron particles by using these lithiated scintillating monoliths was demonstrated.
Bactericidal Effect of TiO2 on the Selected Vibrio Parahaemolyticus and Optimization Using Response Surface Methodology
Authors: Kim Tae-Young , Park Kyung-Hee , Rho Seon-Gyun , Kim Seung-Jai , Cho Sung-Young
Published: November 2006

In this work, the bactericidal effect of TiO2 on selected typical food pathogenic bacteria, Vibrio parahaemolyticus was studied. V. parahaemolyticus is an important pathogen of humans and aquacultured animals. We established the response surface methodology
(Box-Behnken Design) to investigate the effect of principal parameters on the cell sterilization such as TiO2 concentration, UV illumination time, temperature, and pH. The sterilization rate reached maximum value at the TiO2 concentration of 1.0 mg/ml. During irradiation
under the time of 30 min with UV light with the 1g-TiO2/l, the sterilization rate was greater than 85%, and 99% or more cell lost their viability with 3 hours of irradiation. Sterilization rate of the cell increased with decrease in the pH and temperature.
Low Temperature Synthesis of Colloidal CdSe Quantum Dots
Authors: Hwang Seongmi , Choi Youngmin , Ryu Beyong-Hwan
Published: November 2006

In this study, the CdSe nanocrystals were prepared in phenyl ether and octyl amine to investigate the variations of their size, bandgap energy, and photoluminescence with growth time and temperature. The sizes of the CdSe nanocrystals were measured using High Resolution Transmission
Electron Microscopy (HRTEM), and found to be nearly monodisperse for relatively low growth temperature, 130 °C. Their optic properties were characterized by photoluminescence measurements, which showed that the colors of the nanocrystals could be controlled. The bandgap energies of the
nanocrystals were calculated theoretically and found to be in accord with quantum confinement theory. This synthetic method requires only a cheap solvent and offers good reproducibility at a lower price.
Spin-Polarized Current of a Transistor in Single Mn12 Molecular Magnets
Authors: Park Joonho , Yang Heok , Park K.-S. , Lee Eok-Kyun
Published: November 2006

Focusing on the framework of how to realize the molecular spintronics in a single molecular magnet, we present theoretical studies on the spin-polarized quantum transport behavior through a single Mn12 molecular magnet. Our theoretical results were obtained by carrying out
density functional theoretical calculation within the Keldysh nonequilibrium Green function formalism. The ultimate goal of the molecular spintronics is to develop single molecule transistors which generate spin-polarized currents through the molecular magnet. We obtained the densityof states,
the transmission coefficients and the characteristic features of the current–voltage (I–V) on the spin-polarized transport properties of Mn12 by the theoretical calculation. These results show the possibility for the realization of molecular spintroinics using single
molecular magnets.
Device Optimization of CO2 Gas Sensor Using Planar Technology
Authors: Lee Woon Young , Choi Yong Kook , Satyanarayana L. , Park Jin Seong
Published: November 2006

A planar type Li+ ion based potentiometric CO2 micro gas sensor of size 2 × 3 mm has been fabricated on alumina substrate by combining thin and thick film technology. The heater, electrodes and electrolyte were deposited by thin film deposition technique
and the sensing and reference electrodes were printed by silk screen printing technology. The optimal thickness and sintering temperature of electrolyte are 1.2 μm and 775 °C. The sensor with Li2CO3 and 20 mol% BaCO3 not only exhibits a good Nernstian
behavior but also consistent results over a long time at 450 °C in dry as well as 70% RH humidity condition between 160–5000 ppm CO2 concentrations. The spreading effect of the sensing and reference materials was controlled by the addition of Al2O3:B2O3(1:2
mol%) glass.
Fabrication of 3D Functionalized Microstructure via Scanning Probe Lithography and Self-Assembly Methods
Authors: Choi Inhee , Kang Sung Koo , Lee Jeongjin , Kim Younghun , Yi Jongheop
Published: November 2006

A type of 2-dimensional planar pattern with spatial resolution can be easily produced using scanning probe lithography (SPL). However, it has not been used successfully for fabricating 3-dimensional (3D) structures due to the low aspect ratio of the resulting structure. Herein, we describe
a method for fabricating a 3D functionalized structure via a combination of SPL and self-assembly techniques. In this study, a 3D structure was established on a Si surface with a passivated monolayer via SPL. The patterned layer was modified using a ω-functionalized organosilane.
Lateral force microscopy (LFM) was applied to discriminate the chemical functionalities and gold nanoparticles were also used to clearly identify the modified layer.
Photonic Polymer Replicas from Distributed Bragg Reflectors Structured Porous Silicon
Authors: Kim Jihoon , Koh Youngdae , Jang Seunghyun , Ko Young Chun , Woo Hee-Gweon , Sohn Honglae
Published: November 2006

Well defined 1-dimentional (1-D) photonic crystals of polymer replicas have been successfully obtained. DBR porous silicon containing nanometer-scale pores are prepared by an anodic electrochemical etch of p++-type silicon wafer. The resulting DBR porous silicon film removed
from the substrate by applying an electropolishing current has been thermally oxidized in the furnace at 400 °C for 3 h. Oxidized DBR PSi/polystyrene composite films are prepared by casting of polymer solution onto a free-standing porous silicon photonic crystal layer. Flexible photonic
polymer replicas have been prepared after the removal of oxidized DBR PSi matrix in HF/H2O mixture solution. Polymer replicas exhibit a sharp resonance in the reflectivity spectrum. Optical characteristics of photonic polymer replica indicate that the surface of polymer film has
a negative structure of DBR PSi. This replica is stable in aqueous solutions for several days without any degradation.
Catalytic Performance of Nanosized Pt–Au Alloy Catalyst in Oxidation of Methanol and Toluene
Authors: Kim Ki-Joong , Kim Yong-Hwa , Ahn Ho-Geun
Published: November 2006

The alloy formed between a group-VIII metal such as platinum and a group-IB metal such as gold changes the catalytic behavior compared to the monometallic phase, increasing the selectivity toward certain products and also decreasing the deactivation rate. Pt–Au alloy nanoparticles
coated on alumina support were found to be catalytically very active for complete oxidation of methanol and toluene. Furthermore, the nanosized Pt–Au particles were added to ZnO/Al2O3 on monolith catalyst. Also, effect of various parameters such as concentration
of methanol and toluene and feed flow rate was investigated. Au particles were sized in 20∼30 nm and Pt particles were well dispersed. In case of alumina supported powder catalyst, complete oxidation of methanol occurred at a temperature lower than that of toluene. From oxidation activity
of monolithic honeycomb with Pt and Au particles, the conversion of methanol was increased with increasing the concentration of methanol, but conversion of toluene showed a decreasing tendency as the concentration of toluene increased. Also, conversion of methanol over honeycomb catalyst was
not largely affected by feed flow rate, while conversion in toluene oxidation was decreased rapidly as feed flow rate was increased. As a result, the Pt-Au/ZnO/Al2O3/M catalyst used is likely to efficiently treat a large volume of exhaust gas containing VOCs.