bluuebunny/crossref_metadata_2025 huggingface dataset:
Large-Scale Production of Poly(3-Hydroxyoctanoic Acid) by
Pseudomonas putida
GPo1 and a Simplified Downstream Process
Authors: Elbahloul Yasser , Steinbüchel Alexander
Published: December 2008

The suitability of
Pseudomonas putida
GPo1 for large-scale cultivation and production of poly(3-hydroxyoctanoate) (PHO) was investigated in this study. Three fed-batch cultivations of
P. putida
GPo1 at the 350- or 400-liter scale in a bioreactor with a capacity of 650 liters were done in mineral salts medium containing initially 20 mM sodium octanoate as the carbon source. The feeding solution included ammonium octanoate, which was fed at a relatively low concentration to promote PHO accumulation under nitrogen-limited conditions. During cultivation, the pH was regulated by addition of NaOH, NH
4
OH, or octanoic acid, which was used as an additional carbon source. Partial O
2
pressure (pO
2
) was adjusted to 20 to 40% by controlling the airflow and stirrer speed. Under the optimized conditions,
P. putida
GPo1 was able to grow to cell densities as high as 18, 37, and 53 g cells (dry mass) (CDM) per liter containing 49, 55, and 60% (wt/wt) of PHO, respectively. The resulting 40 kg CDM from these three cultivations was used directly for extraction of PHO. Three different methods of extraction of PHO were applied. From these, only acetone extraction showed better performance and resulted in 94% recovery of the PHO contents of cells. A novel mixture of precipitation solvents composed of 70% (vol/vol) methanol and 70% (vol/vol) ethanol was identified in this study. The ratio of PHO concentrate to the mixture was 0.2:1 (vol/vol) and allowed complete precipitation of PHO as white flakes. However, at a ratio of 1:1 (vol/vol) of the solvent mixture to PHO concentrate, a highly purified PHO was obtained. Precipitation yielded a dough-like polymeric material which was cast into thin layers and then shredded into small strips to allow evaporation of the remaining solvents. Gas chromatographic analysis revealed a purity of about 99% ± 0.2% (wt/wt) of the polymer, which consisted mainly of 3-hydroxyoctanoic acid (96 mol%).
Ecological Specialization in a Spatially Structured Population of the Thermophilic Cyanobacterium
Mastigocladus laminosus
Authors: Miller Scott R. , Williams Carin , Strong Aaron L. , Carvey Darla
Published: December 2008

Laboratory evolution experiments suggest the potential for microbial populations to contribute significant ecological variation to ecosystems, yet the functional importance of genetic diversity within natural populations of microorganisms is largely unknown. Here, we investigated the distribution of genetic and phenotypic variation for a population of the cyanobacterium
Mastigocladus laminosus
distributed along the temperature gradient of White Creek, Yellowstone NP. A total of 153 laboratory strains were directly isolated from five sites with mean annual temperatures ranging between 39 and 54°C. Genetic characterization at four nitrogen metabolism genes identified 15 closely related lineages in the population sample. These lineages were distributed nonrandomly along White Creek, but the observed geographic structure could not be explained by limited dispersal capabilities. Temperature performance experiments with six
M. laminosus
lineages that maximized their respective relative abundances at different positions along the gradient provided evidence for niche differentiation within the population. Niche differentiation included a tradeoff in performance at high and low temperatures, respectively. The physiological variation of these lineages in laboratory culture was generally well matched to the prevailing temperature conditions experienced by these organisms in situ. These results suggest that sympatric diversification along an ecological selection gradient can be a potent source of evolutionary innovation in microbial populations.
Quantifying Transmission of
Campylobacter jejuni
in Commercial Broiler Flocks
Authors: van Gerwe Twan , Miflin Jeanette K. , Templeton Jillian M. , Bouma Annemarie , Wagenaar Jaap A. , Jacobs-Reitsma Wilma F. , Stegeman Arjan , Klinkenberg Don
Published: December 2008

Since meat from poultry colonized with
Campylobacter
spp. is a major cause of bacterial gastroenteritis, human exposure should be reduced by, among other things, prevention of colonization of broiler flocks. To obtain more insight into possible sources of introduction of
Campylobacter
into broiler flocks, it is essential to estimate the moment that the first bird in a flock is colonized. If the rate of transmission within a flock were known, such an estimate could be determined from the change in the prevalence of colonized birds in a flock over time. The aim of this study was to determine the rate of transmission of
Campylobacter
using field data gathered for 5 years for Australian broiler flocks. We used unique sampling data for 42
Campylobacter jejuni
-colonized flocks and estimated the transmission rate, which is defined as the number of secondary infections caused by one colonized bird per day. The estimate was 2.37 ± 0.295 infections per infectious bird per day, which implies that in our study population colonized flocks consisting of 20,000 broilers would have an increase in within-flock prevalence to 95% within 4.4 to 7.2 days after colonization of the first broiler. Using Bayesian analysis, the moment of colonization of the first bird in a flock was estimated to be from 21 days of age onward in all flocks in the study. This study provides an important quantitative estimate of the rate of transmission of
Campylobacter
in broiler flocks, which could be helpful in future studies on the epidemiology of
Campylobacter
in the field.
Molecular Epidemiology of
Campylobacter jejuni
Isolates from Wild-Bird Fecal Material in Children's Playgrounds
Authors: French Nigel P. , Midwinter Anne , Holland Barbara , Collins-Emerson Julie , Pattison Rebecca , Colles Frances , Carter Philip
Published: December 2008

In many countries relatively high notification rates of campylobacteriosis are observed in children under 5 years of age. Few studies have considered the role that environmental exposure plays in the epidemiology of these cases. Wild birds inhabit parks and playgrounds and are recognized carriers of
Campylobacter
, and young children are at greater risk of ingesting infective material due to their frequent hand-mouth contact. We investigated wild-bird fecal contamination in playgrounds in parks in a New Zealand city. A total of 192 samples of fresh and dried fecal material were cultured to determine the presence of
Campylobacter
spp.
Campylobacter jejuni
isolates were also characterized by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST), and the profiles obtained were compared with those of human isolates.
C. jejuni
was isolated from 12.5% of the samples. MLST identified members of clonal complexes ST-45, ST-682, and ST-177; all of these complexes have been recovered from wild birds in Europe. PFGE of ST-45 isolates resulted in profiles indistinguishable from those of isolated obtained from human cases in New Zealand. Members of the ST-177 and ST-682 complexes have been found in starlings (
Sturnus vulgaris
) in the United Kingdom, and these birds were common in playgrounds investigated in New Zealand in this study. We suggest that feces from wild birds in playgrounds could contribute to the occurrence of campylobacteriosis in preschool children. Further, the
C. jejuni
isolates obtained in this study belonged to clonal complexes associated with wild-bird populations in the northern hemisphere and could have been introduced into New Zealand in imported wild garden birds in the 19th century.
Host Cell Cytokines Induced by
Chlamydia pneumoniae
Decrease the Expression of Interstitial Collagens and Fibronectin in Fibroblasts
Authors: Baumert Jürgen , Schmidt Karl-Hermann , Eitner Annett , Straube Eberhard , Rödel Jürgen
Published: December 2008

Chlamydia pneumoniae
infection has been associated with chronic obstructive airway disease (COPD), asthma, and atherosclerosis. Inflammation and airway remodeling in asthma and COPD result in subepithelial fibrosis that is characterized by the deposition of interstitial collagens and fibronectin. The progression of atherosclerosis is also accompanied by an increased production of interstitial collagens in the intima. As shown by reverse transcription-PCR and immunoblotting, infection of human fibroblasts and smooth muscle cells by
C. pneumoniae
TW-183 downregulated the expression of type I and III collagen and fibronectin, whereas the level of type IV collagen remained unchanged. Conditioned medium from infected fibroblasts as well as epithelial WISH cells also reduced the expression of interstitial collagens and fibronectin in uninfected cells. In experiments using blocking antibodies, beta interferon was found to contribute to the inhibitory effects of conditioned medium collected from infected fibroblasts. In contrast, downregulation of matrix protein expression by conditioned medium from epithelial cells was caused by interleukin-1α, which was not secreted from fibroblasts following chlamydial infection.
C. pneumoniae
-mediated inhibition of collagen and fibronectin expression was diminished following transfection of fibroblasts with specific small interfering RNA targeting the transcription factor CCAAT/enhancer-binding protein β. The downregulation of interstitial collagens and fibronectin by the
Chlamydia
-induced host cell cytokine response may modulate tissue remodeling processes in airway diseases. In atherosclerosis the inhibition of collagen synthesis by
C. pneumoniae
infection may promote plaque vulnerability, thereby increasing the risk of plaque rupture.
Phosphoinositide 3-Kinase-Dependent Inhibition of Dendritic Cell Interleukin-12 Production byGiardia lamblia
Authors: Kamda Joel Désiré , Singer Steven M.
Published: December 2008

Dendritic cell interactions with pathogenic microbes initiate and direct the development of subsequent adaptive responses. The protozoan pathogenGiardia lambliainfects the mammalian small intestine, leading to nutrient malabsorption and diarrhea but rarely causing inflammation. In order to begin to understand how the innate immune system responds to this parasite and shapes the eventual adaptive response, we examined the interaction between parasites and murine bone marrow-derived dendritic cells (DCs). DCs incubated with live parasites or parasite extracts displayed enhanced levels of CD40. The expression of CD80 and CD86 also increased, but less than was seen with lipopolysaccharide-activated DCs. Small amounts of interleukin-6 (IL-6) and tumor necrosis factor alpha were secreted by these DCs, whereas no IL-10 or IL-12 could be detected. Coincubation of DCs with parasite extracts along with known Toll-like receptor (TLR) ligands resulted in enhanced secretion of IL-10 and reduced secretion of IL-12. The levels of major histocompatibility complex class II, CD80, and CD86 were also reduced compared to DCs stimulated with TLR ligands alone. Finally, studies with an extracellular signal-regulated kinase 1/2 pathway inhibitor, a phosphoinositide 3-kinase (PI3K) inhibitor, and anti-IL-10 receptor antibody revealed that the PI3K pathway is the dominant mechanism of inhibition in DCs incubated with both lipopolysaccharide andGiardia. These data suggest that this parasite actively interferes with host innate immunity, resulting in an immune response able to control the infection but devoid of strong inflammatory signals.
Inhibition of Complement and CD14 Attenuates theEscherichia coli-Induced Inflammatory Response in Porcine Whole Blood
Authors: Thorgersen Ebbe Billmann , Pharo Anne , Haverson Karin , Axelsen Anne K. , Gaustad Peter , Kotwal Girish J. , Sfyroera Georgia , Mollnes Tom Eirik
Published: December 2008

The innate immune response is a double-edged sword in systemic inflammation and sepsis. Uncontrolled or inappropriate activation can damage and be lethal to the host. Several studies have investigated inhibition of downstream mediators, including tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β). Emerging evidence indicates that upstream inhibition is a better therapeutic approach for attenuating damaging immune activation. Therefore, we investigated inhibition of two central innate immune pathways, those of complement and CD14/Toll-like receptor 4 (TLR4)/myeloid differentiation protein 2 (MD-2), in a porcine in vitro model ofEscherichia coli-induced inflammation. Porcine whole blood anticoagulated with lepuridin, which did not interfere with the complement system, was incubated withE. colilipopolysaccharide (LPS) or whole bacteria. Inhibitors of complement and CD14 and thus the LPS CD14/TLR4/MD-2 receptor complex were tested to investigate the effect on the inflammatory response. A broad range of inflammatory readouts were used to monitor the effect. Anti-CD14 was found to saturate the CD14 molecule on granulocytes and completely inhibited LPS-induced proinflammatory cytokines in a dose-dependent manner. Anti-CD14 significantly reduced the levels of theE. coli-induced proinflammatory cytokines TNF-α and IL-1β, but not IL-8, in a dose-dependent manner. No effect on bacterial clearance was seen. Vaccinia complement control protein and smallpox inhibitor of complement enzymes, twoOrthopoxvirus-encoded complement inhibitors, completely inhibited complement activation. Furthermore, these agents almost completely inhibited the expression of wCD11R3, which is associated with CD18 as a β2 integrin, on porcine granulocytes and decreased IL-8 levels significantly in a dose-dependent manner. As expected, complement inhibition reduced bacterial clearance. We conclude that inhibition of complement and CD14 attenuatesE. coli-induced inflammation and might be used as a therapeutic regimen in gram-negative sepsis along with appropriate treatment with antibiotics.
Protein A-Mediated Multicellular Behavior inStaphylococcus aureus
Authors: Merino Nekane , Toledo-Arana Alejandro , Vergara-Irigaray Marta , Valle Jaione , Solano Cristina , Calvo Enrique , Lopez Juan Antonio , Foster Timothy J. , Penadés José R. , Lasa Iñigo
Published: December 2008

The capacity ofStaphylococcus aureusto form biofilms on host tissues and implanted medical devices is one of the major virulence traits underlying persistent and chronic infections. The matrix in whichS. aureuscells are encased in a biofilm often consists of the polysaccharide intercellular adhesin (PIA) or poly-N-acetyl glucosamine (PNAG). However, surface proteins capable of promoting biofilm development in the absence of PIA/PNAG exopolysaccharide have been described. Here, we used two-dimensional nano-liquid chromatography and mass spectrometry to investigate the composition of a proteinaceous biofilm matrix and identified protein A (spa) as an essential component of the biofilm; protein A induced bacterial aggregation in liquid medium and biofilm formation under standing and flow conditions. Exogenous addition of synthetic protein A or supernatants containing secreted protein A to growth media induced biofilm development, indicating that protein A can promote biofilm development without being covalently anchored to the cell wall. Protein A-mediated biofilm formation was completely inhibited in a dose-dependent manner by addition of serum, purified immunoglobulin G, or anti-protein A-specific antibodies. A murine model of subcutaneous catheter infection unveiled a significant role for protein A in the development of biofilm-associated infections, as the amount of protein A-deficient bacteria recovered from the catheter was significantly lower than that of wild-type bacteria when both strains were used to coinfect the implanted medical device. Our results suggest a novel role for protein A complementary to its known capacity to interact with multiple immunologically important eukaryotic receptors.
Evolution of Penicillin-Binding Protein 2 Concentration and Cell Shape during a Long-Term Experiment withEscherichia coli
Authors: Philippe Nadège , Pelosi Ludovic , Lenski Richard E. , Schneider Dominique
Published: December 2008

Peptidoglycan is the major component of the bacterial cell wall and is involved in osmotic protection and in determining cell shape. Cell shape potentially influences many processes, including nutrient uptake as well as cell survival and growth. Peptidoglycan is a dynamic structure that changes during the growth cycle. Penicillin-binding proteins (PBPs) catalyze the final stages of peptidoglycan synthesis. Although PBPs are biochemically and physiologically well characterized, their broader effects, especially their effects on organismal fitness, are not well understood. In a long-term experiment, 12 populations ofEscherichia colihaving a common ancestor were allowed to evolve for more than 40,000 generations in a defined environment. We previously identified mutations in thepbpAoperon in one-half of these populations; this operon encodes PBP2 and RodA proteins that are involved in cell wall elongation. In this study, we characterized the effects of two of these mutations on competitive fitness and other phenotypes. By constructing and performing competition experiments with strains that are isogenic except for thepbpAalleles, we showed that both mutations that evolved were beneficial in the environment used for the long-term experiment and that these mutations caused parallel phenotypic changes. In particular, they reduced the cellular concentration of PBP2, thereby generating spherical cells with an increased volume. In contrast to their fitness-enhancing effect in the environment where they evolved, both mutations decreased cellular resistance to osmotic stress. Moreover, one mutation reduced fitness during prolonged stationary phase. Therefore, alteration of the PBP2 concentration contributed to physiological trade-offs and ecological specialization during experimental evolution.
Involvement of the LuxR-Type Transcriptional Regulator RamA in Regulation of Expression of thegapAGene, Encoding Glyceraldehyde-3-Phosphate Dehydrogenase ofCorynebacterium glutamicum
Authors: Toyoda Koichi , Teramoto Haruhiko , Inui Masayuki , Yukawa Hideaki
Published: December 2008

SugR, RamA, GlxR, GntR1, and a MarR-type transcriptional regulator bind to the promoter region of thegapAgene encoding glyceraldehyde-3-phosphate dehydrogenase (GAPDH), essential for glycolysis inCorynebacterium glutamicum. We previously showed that SugR, a transcriptional repressor of phosphotransferase system genes for the sugar transport system, is involved in the downregulation ofgapAexpression in the absence of sugar. In this study, the role of RamA in the expression of thegapAgene was examined. Comparing thegapAexpression and GAPDH activity of aramAmutant with those of the wild type revealed that RamA is involved in upregulation ofgapAexpression in glucose-grown cells. DNase I footprint analyses and electrophoretic mobility shift assays revealed that RamA binds with different affinities to three sites in thegapApromoter.lacZreporter assays with mutated RamA binding sites in thegapApromoter showed that the middle binding site is the most important for RamA to activategapAexpression and that binding of RamA to thegapApromoter activates the gene expression not only in glucose-grown cells but also in acetate-grown cells. Furthermore, RamA also directly activatessugRexpression, indicating that two global regulators, RamA and SugR, are coordinately involved in the complex regulation ofgapAexpression inC. glutamicum.
The MalF P2 Loop of the ATP-Binding Cassette Transporter MalFGK
2
from
Escherichia coli
and
Salmonella enterica
Serovar Typhimurium Interacts with Maltose Binding Protein (MalE) throughout the Catalytic Cycle
Authors: Daus Martin L. , Grote Mathias , Schneider Erwin
Published: December 2008

We have investigated the interaction of the uncommonly large periplasmic P2 loop of the MalF subunit of the maltose ATP-binding cassette transporter (MalFGK
2
) from
Escherichia coli
and
Salmonella enterica
serovar Typhimurium with maltose binding protein (MalE) by site-specific chemical cross-linking in the assembled transport complex. We focused on possible distance changes between two pairs of residues of the P2 loop and MalE during the transport cycle. The distance between MalF(S205C) and MalE(T80C) (∼5 Å) remained unchanged under all conditions tested. Cross-linking did not affect the ATPase activity of the complex. The distance between MalF(T177C) and MalE(T31C) changed from ∼10 Å to ∼5 Å upon binding of ATP (or maltose, with a less pronounced result) and was reset to ∼10 Å after hydrolysis of one ATP. A cross-link (∼25 Å) between MalF(S205C) and MalE(T31C) was observed only when the transporter resided in a transition state-like conformation, as was the case after vanadate trapping or in a binding protein-independent mutant, both of which are characterized by tight binding of unliganded MalE to the transporter. Thus, we propose that the observed cross-link is indicative of catalytic intermediates of the transporter. Together, our results strengthen the notion that the MalF P2 loop plays an important role in intersubunit communication. In particular, this loop is involved in keeping MalE in close contact with the transporter. The data are discussed with respect to a crystal structure and current transport models.
INVESTIGATION OF THERMAL DIFFUSIVITY–MICROHARDNESS CORRELATION EXTENDED TO SURFACE-NITRURED STEEL USING BOUBAKER POLYNOMIALS EXPANSION
Authors: GHRIB TAHER , BOUBAKER KAREM , BOUHAFS MAHMOUD
Published: December 2008

This study sums up the authors recent works1–6 on steel regarding non-destructive testing and evaluation achieved between 2000 and 2008. The main related items are the establishment of a polynomial correlation4 between the thermal diffusivity and the Vickers' hardness HV using the recently established Boubaker polynomial expansion. This correlation is undoubtedly an efficient guide to set an NDT protocol to investigate steel-strengthened surface performance. Special attention is given to carburized steel material,6 as the existence of any appropriated NDT photothermal technique is demonstrated2,5,6 to be unavoidably subjected to some restrictive conditions. The perspectives of the new features of this recent technique are discussed, with special concern with differently treated material like nitrured and nitrocarburized quenched steel.
VIBRATIONAL MODES STUDY OF METHYL ORANGE USING SERS-MEASUREMENT AND THE DFT METHOD
Authors: JIA TING-JIAN , SONG GE , LI PENG-WEI , HE TING-CHAO , MO YU-JUN , CUI YU-TING
Published: December 2008

This paper experimentally observes the Normal Raman spectrum (NRS) and infrared absorption spectrum of methyl orange (MO) and presents theoretical vibrational spectra calculated from a density functional theory (DFT) method on the basis of B3LYP with 6–31 basis set. The calculated results show very good agreement with the experimentally observed IR and Raman frequencies. We also report the surface enhanced Raman spectrum (SERS) of MO adsorbed on silver nanoparticles surface. Finally, the possible adsorbed state of MO on the silver nanoparticles surface is discussed.
IMPURITY ENTANGLEMENT IN THE OPEN-ENDED HEISENBERG CHAINS
Authors: HU MING-LIANG
Published: December 2008

By using the concept of concurrence, we study pairwise entanglement between the two end spins in the open-ended Heisenberg XXX and XY chains up to ten spins. The results show that by introducing two boundary impurities, one can obtain maximum entanglement at the limit of the impurity parameter |J1| ≪ J for the even-number qubits. When |J1/J| > 0, the entanglement always decreases with the increase in the absolute value of J1/J, and for the Heisenberg XXX chain, C disappears when J1/J exceeds a certain critical point Jic, and attains an asymptotic value C0 when |J1| ≫ J(J1 < 0), while for the Heisenberg XY chain, C always disappears when |J1/J| exceeds a certain critical point Jic. Both C0 and Jic decrease with the increase of the length of the chain.
SUPERCONDUCTING STATE PARAMETERS OF 4d-TRANSITION METALS BASED BINARY ALLOYS
Authors: VORA ADITYA M.
Published: December 2008

The theoretical study of the superconducting state parameters (SSP) viz. electron–phonon coupling strength λ, Coulomb pseudopotential μ*, transition temperature TC, isotope effect exponent α and effective interaction strength NoV of 4d-transition metals based binary alloys have been made extensively in the present work using a model potential formalism for the first time. In the present computation, the use of pseudo-alloy-atom model (PAA) is proposed and found successful. A considerable influence of various exchange and correlation functions on λ and μ* is found from the present study. The present results of the SSP are found in qualitative agreement with the available experimental data wherever they exist.
TRANSMISSION AND DIFFRACTION THROUGH METALLIC NANOSLIT
Authors: LIU JUAN , HU BIN , XIE JING-HUI , WANG YONG-TIAN
Published: December 2008

The extraordinary optical transmission (EOT) and diffraction through nanoslit composed of two finite-width metallic films with periodic or aperiodic sub-wavelength corrugation were studied. The transmitted spectra were calculated and compared, and the numerical results showed that two transmission peaks exist for the periodic corrugation, while for aperiodic one the transmission peaks are split into seven, corresponding to their different periods and couplings. Further investigation indicated that resonant wavelength of Surface Plasmon Polaritons (SPPs) determined by the nanoslit can be distinguished. It is expected that this investigation will provide useful information for further designing various nano-scaled optical filters and wavelength division multiplexer (WDM) in the next all optical network (AON).
TERAHERTZ WAVES HAIRPIN MICROSTRIP BAND-PASS FILTER AND ITS APPLICATION TO OVERLAID DIELECTRIC MATERIAL DETECTION
Authors: SI LI-MING , LV XIN
Published: December 2008

A novel terahertz (THz) waves band-pass filter with the center frequency of 880 GHz and low insertion loss using microstrip line hairpin resonators is introduced. The properties of this filter are investigated by finite element method (FEM) simulations. The numerical result shows that the filter has a 3 dB bandwidth from 865 GHz to 892 GHz and has 80 GHz bandwidth better than -10 dB. Resonance frequency shifts of the filter covered by dielectric materials of different permittivity and thickness are calculated, which shows that this type of filter is suitable for detecting the properties of overlaid dielectric materials.
LIPSCHITZ EQUIVALENCE OF GENERAL SIERPINSKI CARPETS
Authors: DAI MEIFENG
Published: December 2008

Recently, a lot of work has been devoted to the study of the Lipschitz equivalence between self-similar sets. Many related results on self-similar sets of the real line have been well-known under the condition that the similarity ratios equal each other. In this paper, we generalize some results to a more general setting. We mainly study the Lipschitz equivalence between two general Sierpinski carpets in ℝ2.
DLCA AND LANGEVIN DYNAMICS APPROACHES OF SOL GEL TRANSITION: A COMPARISON VIA THE FRACTAL DIMENSION DURING AGGREGATION
Authors: HSIEH K. , LALLET F. , OLIVI-TRAN N.
Published: December 2008

We compared two models of aggregation which represent the sol gel transition of base-catalyzed colloidal gels. The two models are a Langevin dynamics approach of this transition and the DLCA model (diffusion limited cluster-cluster aggregation). For large numbers of particles, we compared the fractal dimension of the gelling network via the structure factor of the bulk. We observed that the Langevin dynamics approach did give more realistic fractal dimension than the DLCA model. This is due to the fact that Langevin dynamics evolves as a function of a physical time.
BELLS GALORE: OSCILLATIONS AND CIRCLE-MAP DYNAMICS FROM SPACE-FILLING FRACTAL FUNCTIONS
Authors: PUENTE CARLOS E. , CORTIS ANDREA , SIVAKUMAR BELLIE
Published: December 2008

The construction of a host of interesting patterns over one and two dimensions, as transformations of multifractal measures via fractal interpolating functions related to simple affine mappings, is reviewed. It is illustrated that, while space-filling fractal functions most commonly yield limiting Gaussian distribution measures (bells), there are also situations (depending on the affine mappings' parameters) in which there is no limit. Specifically, the one-dimensional case may result in oscillations between two bells, whereas the two-dimensional case may give rise to unexpected circle map dynamics of an arbitrary number of two-dimensional circular bells. It is also shown that, despite the multitude of bells over two dimensions, whose means dance making regular polygons or stars inscribed on a circle, the iteration of affine maps yields exotic kaleidoscopes that decompose such an oscillatory pattern in a way that is similar to the many cases that converge to a single bell.
Contraction-stimulated glucose transport in rat skeletal muscle is sustained despite reversal of increased PAS-phosphorylation of AS160 and TBC1D1
Authors: Funai Katsuhiko , Cartee Gregory D.
Published: December 2008

Akt substrate of 160 kDa (AS160), the most distal insulin signaling protein known to be important for insulin-stimulated glucose transport, becomes phosphorylated with skeletal muscle contraction. Akt, AMP-activated protein kinase (AMPK), and Ca2+/calmodulin-dependent kinase II (CaMKII) have been implicated in regulating AS160 and/or glucose transport. Our primary aim was to assess time courses for contraction's effects on glucose transport and phosphorylation of Akt, AMPK, CaMKII, and AS160. Isolated rat epitrochlearis muscles were studied without or with contraction (5, 10, 20, 40, 60 min). Phospho-Akt substrate (PAS) antibody was used to measure AS160 PAS phosphorylation by quantifying the ∼160-kDa band on PAS immunoblots (PAS-160); a separate band at 150 kDa (PAS-150) that responded similarly to contraction was also identified. Using specific antibodies for AS160 or TBC1D1 on immunoblots, the molecular mass of PAS-160 was found to correspond with that of AS160 and not TBC1D1, whereas PAS-150 corresponded with TBC1D1 and not AS160. Furthermore, supernatant of sample immunodepleted with anti-AS160 had greatly reduced PAS-160, whereas supernatant of sample immunodepleted with anti-TBC1D1 had greatly reduced PAS-150, providing further evidence that PAS-160 and PAS-150 correspond with PAS-AS160 and PAS-TBC1D1, respectively. Contraction induced transient increases in PAS-160, PAS-150, phospho-glycogen synthase kinase 3 (an Akt substrate) and phospho-CaMKII; glucose transport and phospho-AMPK increases were maintained for 60 min of contraction. These data suggest the following: 1) PAS-160 (AS160) and PAS-150 (TBC1D1) respond to contraction transiently, despite sustained stimulation; 2) continual AMPK activation was insufficient for sustained increase in PAS-160 or PAS-150; and 3) sustained elevation of PAS-160 or PAS-150 was unnecessary to maintain contraction-stimulated glucose transport for up to 60 min.
Structure solution and refinement from powder or single-crystal diffraction data? Pros and cons: An example of the high-pressureβ′-polymorph of glycine
Authors: Tumanov Nickolay A. , Boldyreva Elena V. , Ahsbahs Hans
Published: December 2008

The structure of a high-pressure polymorph of glycine (theβ′-polymorph formed reversibly at 0.8 GPa from theβ-polymorph) was determined from high-resolution X-ray powder diffraction data collectedin situin a diamond anvil cell at nine pressure points up to 2.6 GPa. X-ray powder diffraction study gave a structural model of at least the same quality as that obtained from a single-crystal diffraction experiment. The difference between the powder-diffraction and the single-crystal models is related to the orientation of the NH3-tails and the structure of the hydrogen-bonds network. The phase transition between theβ- andβ′-polymorphs is reversible and preserves a single crystal intact. No transformations were observed between theβ-,α-, andβ′-polymorphs on compression and decompression, although theα- andβ′-polymorphs belong to the same space group (P21/c). The instability of theβ- andγ-forms with pressure can be predicted easily when considering the densities of their structures versus pressure. The direction of the transformation (i.e., which of the high-pressure polymorphs is formed) is determined by structural filiation between the parent and the high-pressure phases because of the kinetic control of the transformations.
Chemical reactions in the Co–Si–C system
Authors: Guo Yu , Yuan Wenxia , Song Bo , Xu Yanping
Published: December 2008

Isothermal sections at 1100 and 1500 °C were determined by X-ray powder diffraction method to reveal stable phases and chemical pathways in the Co–Si–C system. There is no ternary compound present in either isothermal. Cobalt silicides are formed in the Co-rich region at temperatures lower than those in the Si-rich region.
CoSi2 reacts with carbon to form CoSi and SiC at 1500 °C, and
Co2Si
and CoSi are more stable in equilibrium with carbon. The results are also discussed in terms of thermodynamics and binding energy of the reacting substances.
Apocynin: Molecular Aptitudes
Authors: Stefanska J. , Pawliczak R.
Published: December 2008

Apocynin is a naturally occurring methoxy‐substituted catechol, experimentally used as an inhibitor of NADPH‐oxidase. It can decrease the production of superoxide () from activated neutrophils and macrophages while the ability of phagocytosis remains unaffected. The anti‐inflammatory activity of apocynin has been demonstrated in a variety of cell and animal models of inflammation. Apocynin, after metabolic conversion, inhibits the assembly of NADPH‐oxidase that is responsible for reactive oxygen species (ROS) production. It is, therefore, extensively used to reveal the role of this enzyme in cell and experimental models. Although some of the ROS serve as signaling molecules in the cells, excessive production is damaging and has been implicated to play an important role in the progression of many disease processes. This is why in many studies apocynin presents a promising potential treatment for some disorders; however, its utility with inflammatory diseases remains to be determined. Since its mode of action is not well defined, we tried to get a more precise insight into the mechanisms by which apocynin exerts its activity. Considering the anti‐inflammatory activities of apocynin, we may conclude that this compound definitely deserves further study.
Comparative Analysis of Fatty Acid Desaturases in Cyanobacterial Genomes
Authors: Chi Xiaoyuan , Yang Qingli , Zhao Fangqing , Qin Song , Yang Yu , Shen Junjun , Lin Hanzhi
Published: December 2008

Fatty acid desaturases are enzymes that introduce double bonds into the hydrocarbon chains of fatty acids. The fatty acid desaturases from 37 cyanobacterial genomes were identified and classified based upon their conserved histidine-rich motifs and phylogenetic analysis, which help to determine the amounts and distributions of desaturases in cyanobacterial species. The filamentous orN2-fixing cyanobacteria usually possess more types of fatty acid desaturases than that of unicellular species. The pathway of acyl-lipid desaturation for unicellular marine cyanobacteriaSynechococcusandProchlorococcusdiffers from that of other cyanobacteria, indicating different phylogenetic histories of the two genera from other cyanobacteria isolated from freshwater, soil, or symbiont. StrainGloeobacter violaceusPCC 7421 was isolated from calcareous rock and lacks thylakoid membranes. The types and amounts of desaturases of this strain are distinct to those of other cyanobacteria, reflecting the earliest divergence of it from the cyanobacterial line. Three thermophilic unicellular strains,Thermosynechococcus elongatusBP-1 and twoSynechococcusYellowstone species, lack highly unsaturated fatty acids in lipids and contain only oneΔ9desaturase in contrast with mesophilic strains, which is probably due to their thermic habitats. Thus, the amounts and types of fatty acid desaturases are various among different cyanobacterial species, which may result from the adaption to environments in evolution.
A New‐Trend Model‐Based to Solve the Peak Power Problems in OFDM Systems
Authors: Eltholth Ashraf A. , Mekhail Adel R. , Elshirbini A. , Dessouki M. I. , Abdelfattah A. I.
Published: December 2008

The high peak to average power ration (PAR) levels of orthogonal frequency division multiplexing (OFDM) signals attract the attention of many researchers during the past decade. Existing approaches that attack this PAR issue are abundant, but no systematic framework or comparison between them exists to date. They sometimes even differ in the problem definition itself and consequently in the basic approach to follow. In this paper, we propose a new trend in mitigating the peak power problem in OFDM system based on modeling the effects of clipping and amplifier nonlinearities in an OFDM system. We showed that the distortion due to these effects is highly related to the dynamic range itself rather than the clipping level or the saturation level of the nonlinear amplifier, and thus we propose two criteria to reduce the dynamic range of the OFDM, namely, the use of MSK modulation and the use of Hadamard transform. Computer simulations of the OFDM system using Matlab are completely matched with the deduced model in terms of OFDM signal quality metrics such as BER, ACPR, and EVM. Also simulation results show that even the reduction of PAR using the two proposed criteria is not significat, and the reduction in the amount of distortion due to HPA is truley delightful.
Adjoint and Trivial Cohomologies of Nilpotent Complex Lie Algebras of Dimension ≤7
Authors: Magnin L.
Published: December 2008

We present tables for adjoint and trivial cohomologies of complex nilpotent Lie
algebras of dimension ≤7. Attention is paid to quadratic Lie algebras, Poincaré duality,
and harmonic cocycles.
EBV-Associated Smooth Muscle Neoplasms: Solid Tumors Arising in the Presence of Immunosuppression and Autoimmune Diseases
Authors: Moore Dalal Kimberly , Antonescu Cristina R. , DeMatteo Ronald P. , Maki Robert G.
Published: December 2008

Background. Epstein-Barr virus (EBV)-related smooth muscle neoplasms (SMNs) have been associated with immune dysregulation, most notably in patients who have undergone solid organ transplantation or in patients with HIV/AIDS.Objective. to report our experience with EBV-related neoplasms as well as describing the first EBV-related SMN in the setting of administration of glucocorticoids and the tumor necrosis factor inhibitor etanercept.Design. We have case reports, of minimum 3-year follow-up, 2002–2005.Setting. It was held in an academic and tertiary referral cancer center.Patients. Patients are with dysregulated immunity after solid organ transplantation, HIV/AIDS, or with psoriasis after treatment with etanercept.Interventions. There were discontinuation of etanercept, right hepatic trisegmentectomy, and chemotherapy.Measurements. We use survival as a measurement here.Results. Patients who were able to withstand reduction in immunosuppression survived. Surgical resection or chemotherapy was successful in delaying progression of disease.Limitations. There was a relatively short follow-up for these slow-growing neoplasms.Conclusion. EBV-related SMNs have variable aggressiveness. While chemotherapy may slow disease progression, resection and improving the host immune status provide the best opportunity for primary tumor control.
An Adaptive Systematic Lossy Error Protection Scheme for Broadcast Applications Based on Frequency Filtering and Unequal Picture Protection
Authors: Ramon Marie , Coudoux François-Xavier , Gazalet Marc
Published: December 2008

Systematic lossy error protection (SLEP) is a robust error resilient mechanism based on principles of Wyner-Ziv (WZ) coding for video transmission over error-prone networks. In an SLEP scheme, the video bitstream is separated into two parts: a systematic part consisting of a video sequence transmitted without channel coding, and additional information consisting of a WZ supplementary stream. This paper presents an adaptive SLEP scheme in which the WZ stream is obtained by frequency filtering in the transform domain. Additionally, error resilience varies adaptively depending on the characteristics of compressed video. We show that the proposed SLEP architecture achieves graceful degradation of reconstructed video quality in the presence of increasing transmission errors. Moreover, it provides good performances in terms of error protection as well as reconstructed video quality if compared to solutions based on coarser quantization, while offering an interesting embedded scheme to apply digital video format conversion.
Progesterone Withdrawal-Evoked Plasticity of Neural Function in the Female Periaqueductal Grey Matter
Authors: Lovick T. A. , Devall A. J.
Published: December 2008

Cyclical changes in production of neuroactive steroids during the oestrous cycle induce significant changes inGABAAreceptor expression in female rats. In the periaqueductal grey (PAG) matter, upregulation ofα4β1δGABAAreceptors occurs as progesterone levels fall during late dioestrus (LD) or during withdrawal from an exogenous progesterone dosing regime. The new receptors are likely to be extrasynaptically located on the GABAergic interneurone population and to mediate tonic currents. Electrophysiological studies showed that whenα4β1δGABAAreceptor expression was increased, the excitability of the output neurones in the PAG increased, due to a decrease in the level of ongoing inhibitory tone from the GABAergic interneurones. The functional consequences in terms of nociceptive processing were investigated in conscious rats. Baseline tail flick latencies were similar in all rats. However, acute exposure to mild vibration stress evoked hyperalgesia in rats in LD and after progesterone withdrawal, in line with the upregulation ofα4β1δGABAAreceptor expression.
Performance Simulations of Moving Target Search Algorithms
Authors: Loh Peter K. K. , Prakash Edmond C.
Published: December 2008

The design of appropriate moving target search (MTS) algorithms for computer‐generated bots poses serious challenges as they have to satisfy stringent requirements that include computation and execution efficiency. In this paper, we investigate the performance and behaviour of existing moving target search algorithms when applied to search‐and‐capture gaming scenarios. As part of the investigation, we also introduce a novel algorithm known as abstraction MTS. We conduct performance simulations with a game bot and moving target within randomly generated mazes of increasing sizes and reveal that abstraction MTS exhibits competitive performance even with large problem spaces.
Hepatocyte Growth Factor, but not Vascular Endothelial Growth Factor, Attenuates Angiotensin II–Induced Endothelial Progenitor Cell Senescence
Authors: Sanada Fumihiro , Taniyama Yoshiaki , Azuma Junya , Iekushi Kazuma , Dosaka Norio , Yokoi Toyohiko , Koibuchi Nobutaka , Kusunoki Hiroshi , Aizawa Yoshifusa , Morishita Ryuichi
Published: December 2008

Although both hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) are potent angiogenic growth factors in animal models of ischemia, their characteristics are not the same in animal experiments and clinical trials. To elucidate the discrepancy between HGF and VEGF, we compared the effects of HGF and VEGF on endothelial progenitor cells under angiotensin II stimulation, which is a well-known risk factor for atherosclerosis. Here, we demonstrated that HGF, but not VEGF, attenuated angiotensin II–induced senescence of endothelial progenitor cells through a reduction of oxidative stress by inhibition of the phosphatidylinositol-3,4,5-triphosphate/rac1 pathway. Potent induction of neovascularization of endothelial progenitor cells by HGF, but not VEGF, under angiotensin II was also confirmed by in vivo experiments using several models, including HGF transgenic mice.
“Pulse” Treatment With High-Dose Angiotensin Blocker Reverses Renal Arteriolar Hypertrophy and Regresses Hypertension
Authors: Ishiguro Kimiko , Hayashi Kaori , Sasamura Hiroyuki , Sakamaki Yusuke , Itoh Hiroshi
Published: December 2008

One ultimate goal of hypertension therapy is to cause permanent reversal (“regression”) of already established hypertension. Our aim was to examine whether high-dose “pulse” treatment with a renin-angiotensin system inhibitor could cause regression of established hypertension and to link this action to reversal of arteriolar hypertrophy and changes in vascular matrix metalloproteinase activities. First, 16-week-old male spontaneously hypertensive rats (n=60) were pulse treated for 2 weeks with high-dose angiotensin-converting enzyme inhibitor (enalapril), angiotensin receptor blocker (candesartan), calcium channel blocker (nifedipine), or vasodilator (hydralazine) with or without salt restriction, and the long-term effects on blood pressure were examined. Second, spontaneously hypertensive rats were treated with angiotensin receptor blocker or calcium channel blocker, and the effects on renal gene expressions, arteriolar structure, and vascular matrix metalloproteinase were compared. Treatment of spontaneously hypertensive rats with different antihypertensive agents caused apparently similar reductions in blood pressure during the course of the pulse treatment, within the limitations of the tail-cuff method. After cessation of medications, blood pressure in the rats treated with renin-angiotensin system inhibitor remained reduced by >30 to 40 mm Hg for 4 months. No such effect was seen with calcium channel blocker or vasodilator. The 2-week angiotensin receptor blocker treatment induced a marked reversal of the arteriolar hypertrophy specifically in the small (30 to 100 μm) renal arterioles, together with increased expression and activity of matrix metalloproteinase-13. In conclusion, transient high-dose pulse treatment with angiotensin receptor blocker caused changes in vascular matrix metalloproteinase activity, specific reversal of renal arteriolar hypertrophy, and regression of hypertension in spontaneously hypertensive rats.
Continuous Activation of Renin-Angiotensin System Impairs Cognitive Function in Renin/Angiotensinogen Transgenic Mice
Authors: Inaba Shinji , Iwai Masaru , Furuno Megumi , Tomono Yumiko , Kanno Harumi , Senba Izumi , Okayama Hideki , Mogi Masaki , Higaki Jitsuo , Horiuchi Masatsugu
Published: December 2008

We examined the possibility that continuous activation of the human brain renin-angiotensin system causes cognitive impairment, using human renin (hRN) and human angiotensinogen (hANG) gene chimeric transgenic (Tg) mice. Cognitive function was evaluated by the shuttle avoidance test once a week from 10 to 20 weeks of age. The avoidance rate in wild-type mice gradually increased. In contrast, the avoidance rate in chimeric hRN/hANG-Tg mice also increased; however, no further increase in avoidance rate was observed from 14 weeks of age, and it decreased thereafter. Cerebral surface blood flow was markedly reduced in 20-week-old hRN/hANG-Tg mice. Superoxide anion production in the brain was already higher in 10-week-old hRN/hANG-Tg mice and further increased thereafter with an increase in NADPH oxidase activity. Moreover, expression of p47phoxand Nox4 in the brain of hRN/hANG-Tg mice also increased. Administration of an angiotensin II type 1 receptor blocker, olmesartan (5.0 mg/kg per day), attenuated the increase in blood pressure and ameliorated cognitive decline with enhancement of cerebral surface blood flow and a reduction of oxidative stress in hRN/hANG-Tg mice. On the other hand, hydralazine (0.5 mg/kg per day) did not improve the decrease in avoidance rate, and did not influence cerebral surface blood flow or oxidative stress in hRN/hANG-Tg mice, in spite of a similar reduction of blood pressure to that by olmesartan. Moreover, we observed that treatment with Tempol improved impaired cognitive function in hRN/hANG-Tg mice. These results suggest that continuous activation of the brain renin-angiotensin system impairs cognitive function via stimulation of the angiotensin II type 1 receptor with a decrease in cerebral surface blood flow and an increase in oxidative stress.