bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of the paraventricular nucleus of the hypothalamus in the regulation of cardiac and renal sympathetic nerve activity in conscious normal and heart failure sheep
Authors: Ramchandra Rohit , Hood Sally G. , Frithiof Robert , McKinley Michael J. , May Clive N.
Published: May 2012

Key points

Heart failure is associated with large increases in sympathetic nerve activity to organs like the heart and kidney and this increase is detrimental to patients.

We explored the role played by the paraventricular nucleus of the hypothalamus (PVN), a central brain region, in mediating the increase in sympathetic drive during heart failure.

We show that neurons in the PVN selectively mediate changes in sympathetic drive to the kidney, but not to the heart when blood volume is increased.

In addition, neurons in the PVN do not contribute to the resting levels of sympathetic drive to the heart during normal conditions or in heart failure.

Our data demonstrates striking differences in the central mechanisms that control sympathetic drive to the heart and kidney during heart failure.

Abstract  The paraventricular nucleus of the hypothalamus (PVN) plays a major role in central cardiovascular and volume control, and has been implicated in controlling sympathetic nerve activity (SNA) during volume expansion and in heart failure (HF). The objectives were to determine the role of the PVN on cardiac and renal SNA (CSNA and RSNA) in conscious normal sheep and sheep with pacing‐induced heart failure. In normovolaemic sheep in the normal state and in HF, bilateral microinjection of the GABA agonist muscimol (2 mm, 500 nl), had no effects on resting mean arterial pressure (MAP), heart rate (HR), CSNA or RSNA. In addition, neither chemical inhibition of the PVN using the inhibitory amino acid glycine (0.5 m, 500 nl), nor electrolytic lesion of the PVN reduced the elevated level of CSNA in HF. Dysinhibition of the PVN with bilateral microinjection of bicuculline (1 mm, 500 nl) in normal sheep increased MAP, HR and CSNA, but decreased RSNA, whereas in HF bicuculline had no effects on MAP, HR or CSNA, but inhibited RSNA. During volume expansion in normal sheep, muscimol reversed the inhibition of RSNA, but not of CSNA. In summary, removal of endogenous GABAergic inhibition to the PVN indicated that CSNA is normally under inhibitory control. Although this inhibition was absent in HF, the responses to pharmacological inhibition, or lesion of the PVN, indicates that it does not drive the increased CSNA in HF. These findings indicate the PVN has a greater influence on RSNA than CSNA in the resting state in normal and HF sheep, and during volume expansion in normal sheep.
Speeding Up Particle Trajectory Simulations Under Moving Force Fields using Graphic Processing Units
Authors: Patro Robert , Dickerson John P. , Bista Sujal , Gupta Satyandra K. , Varshney Amitabh
Published: May 2012

In this paper, we introduce a graphic processing unit (GPU)-based framework for simulating particle trajectories under both static and dynamic force fields. By exploiting the highly parallel nature of the problem and making efficient use of the available hardware, our simulator exhibits a significant speedup over its CPU-based analog. We apply our framework to a specific experimental simulation: the computation of trapping probabilities associated with micron-sized silica beads in optical trapping workbenches. When evaluating large numbers of trajectories (4096), we see approximately a 356 times speedup of the GPU-based simulator over its CPU-based counterpart.
Three-Dimensional Free Vibration Analysis of Functionally Graded Annular Plates on Elastic Foundations via State-Space Based Differential Quadrature Method
Authors: Jodaei A. , Yas M. H.
Published: May 2012

In this paper, free vibration of functionally graded annular plates on elastic foundations, based on the three-dimensional theory of elasticity, using state-space based differential quadrature method for different boundary conditions is investigated. The foundation is described by the Pasternak or two-parameter model. Assuming the material properties having an exponent-law variation along the thickness, a semi-analytical approach that makes use of state-space method in thickness direction and one-dimensional differential quadrature method in radial direction is used to obtain the vibration frequencies. Supposed state variables in the present method are different from what have been used for functionally graded annular plate so far. They are a combination of three displacement parameters and three stresses parameters. Numerical results are given to demonstrate the convergency and accuracy of the present method. In addition, the influences of the Winkler and shearing layer elastic coefficients of the foundations and some parameters are also investigated.
Steady State Heat Transfer Within a Nanoscale Spatial Domain
Authors: Poletkin Kirill V. , Kulish Vladimir
Published: May 2012

In this paper, we study the steady state heat transfer process within a spatial domain of the transporting medium whose length is of the same order as the distance traveled by thermal waves. In this study, the thermal conductivity is defined as a function of a spatial variable. This is achieved by analyzing an effective thermal diffusivity that is used to match the transient temperature behavior in the case of heat wave propagation by the result obtained from the Fourier theory. Then, combining the defined size-dependent thermal conductivity with Fourier’s law allows us to study the behavior of the heat flux at nanoscale and predict that a decrease of the size of the transporting medium leads to an increase of the heat transfer coefficient which reaches its finite maximal value, contrary to the infinite value predicted by the classical theory. The upper limit value of the heat transfer coefficient is proportional to the ratio of the bulk value of the thermal conductivity to the characteristic length of thermal waves in the transporting medium.
Inlet and Outlet Pressure-Drop Effects on the Determination of Permeability and Form Coefficient of a Porous Medium
Authors: Naaktgeboren C. , Krueger P. S. , Lage J. L.
Published: May 2012

The determination of permeability K and form coefficient C, defined by the Hazen-Dupuit-Darcy (HDD) equation of flow through a porous medium, requires the measurement of the total pressure drop caused by the porous medium (i.e., inlet, core, and outlet) per unit of porous medium length. The inlet and outlet pressure-drop contributions, however, are not related to the porous medium length. Hence, for situations in which these pressure drops are not negligible, e.g., for short or very permeable porous media core, the definition of K and C via the HDD equation becomes ambiguous. This aspect is investigated analytically and numerically using the flow through a restriction in circular pipe and parallel plates channels. Results show that inlet and outlet pressure-drop effects become increasingly important when the inlet and outlet fluid surface-fraction φ decreases and the Reynolds number Re increases for both laminar and turbulent flow regimes. A conservative estimate of the minimum porous medium length beyond which the core pressure drop predominates over the inlet and outlet pressure drop is obtained by considering a least restrictive porous medium core. Finally, modified K and C are proposed and predictive equations, accurate to within 2.5%, are obtained for both channel configurations with Re ranging from 10−2 to 102 and φ from 6% to 95%.
Electron beam lithography on vertical side faces of micrometer-order Si block
Authors: Yamazaki Kenji , Yamaguchi Hiroshi
Published: May 2012

Electron beam (EB) nanolithography on resist films coated on vertical side faces of Si blocks with micrometer-order size is demonstrated. This is achieved by combining the authors’ original three-dimensional (3D) EB writing technique with the authors’ newly developed low-viscosity resist solution. Resist coating with a 2-butanone/hexane low-viscosity solution enables the authors to uniformly coat a high-resolution EB resist [poly(methyl methacrylate)] on the vertical side faces of Si blocks. The mechanism of uniform coating on the vertical side faces can be understood by considering the lower viscosity of the authors’ resist solution. Moreover, Monte Carlo simulation and experimental 3D EB lithography reveal that dense nanopatterning on opposite side faces of a micrometer-order block with simultaneous development is as attainable as that on a flat substrate. The combination of the resist-coating method and 3D EB writing with ion etching from horizontal directions of substrates is promising for creating 3D nanostructures in semiconductors and thus for 3D nanotechnology.
An uninvited guest: The positron in early 1930s physics
Authors: Leone Matteo , Robotti Nadia
Published: May 2012

A few months before its “official” discovery in September 1932 by Anderson at Cal Tech in Pasadena, the positron was almost simultaneously observed by no less than two additional research teams: one at Cavendish Laboratory in Cambridge, England, and one at Institut du Radium in Paris, France. In this paper, we examine this curious case of multiple independent observations by studying the primary literature. This study identifies the motivations that led these researchers to independently design the experiments suitable for the detection of this novel particle and shows that none of these teams were looking for a positive electron.
Color and Movement
Authors: Stern Peter R.
Published: May 2012

Fly photoreceptors that detect colors also contribute information to the processing of motion.
In Vitro
Analyses of Ethanol Activity against Candida albicans Biofilms
Authors: Rane Hallie S. , Bernardo Stella M. , Walraven Carla J. , Lee Samuel A.
Published: May 2012

Candida albicans
is a common cause of catheter-related bloodstream infections (CR-BSI). Ethanol (EtOH) lock therapy has been attempted despite limited data on optimal dose and duration. Concentrations of 35% EtOH or higher for a minimum of 4 h demonstrated a >99% reduction in mature
C. albicans
biofilm metabolic activity and prevented regrowth. Concentrations of 10% EtOH or higher reduced
C. albicans
biofilm formation by >99%. Further investigation of EtOH lock therapy for treatment and prevention of
C. albicans
CR-BSI is warranted.
Inducible and Constitutive Activation of Two Polymorphic Promoter Alleles of the Candida albicans Multidrug Efflux Pump
MDR1
Authors: Sasse Christoph , Schillig Rebecca , Reimund Alexandra , Merk Julia , Morschhäuser Joachim
Published: May 2012

Overexpression of the multidrug efflux pump
MDR1
confers resistance to the antifungal drug fluconazole on
Candida albicans
. It has been reported that two types of
MDR1
promoters exist in
C. albicans
and that homozygosity for the allele with higher activity may promote fluconazole resistance. We found that the two
MDR1
promoter alleles in strain SC5314 were equally well activated by inducing chemicals or hyperactive forms of the transcription factors Mrr1 and Cap1, which control
MDR1
expression. In addition, no loss of heterozygosity at the
MDR1
locus was observed in
MDR1
-overexpressing clinical
C. albicans
strains that developed fluconazole resistance during therapy.
Novel Antibiotics Targeting Respiratory ATP Synthesis in Gram-Positive Pathogenic Bacteria
Authors: Balemans Wendy , Vranckx Luc , Lounis Nacer , Pop Ovidiu , Guillemont Jérôme , Vergauwen Karen , Mol Selena , Gilissen Ron , Motte Magali , Lançois David , De Bolle Miguel , Bonroy Kristien , Lill Holger , Andries Koen , Bald Dirk , Koul Anil
Published: May 2012

Emergence of drug-resistant bacteria represents a high, unmet medical need, and discovery of new antibacterials acting on new bacterial targets is strongly needed. ATP synthase has been validated as an antibacterial target in
Mycobacterium tuberculosis
, where its activity can be specifically blocked by the diarylquinoline TMC207. However, potency of TMC207 is restricted to mycobacteria with little or no effect on the growth of other Gram-positive or Gram-negative bacteria. Here, we identify diarylquinolines with activity against key Gram-positive pathogens, significantly extending the antibacterial spectrum of the diarylquinoline class of drugs. These compounds inhibited growth of
Staphylococcus aureus
in planktonic state as well as in metabolically resting bacteria grown in a biofilm culture. Furthermore, time-kill experiments showed that the selected hits are rapidly bactericidal. Drug-resistant mutations were mapped to the ATP synthase enzyme, and biochemical analysis as well as drug-target interaction studies reveal ATP synthase as a target for these compounds. Moreover, knockdown of the ATP synthase expression strongly suppressed growth of
S. aureus
, revealing a crucial role of this target in bacterial growth and metabolism. Our data represent a proof of principle for using the diarylquinoline class of antibacterials in key Gram-positive pathogens. Our results suggest that broadening the antibacterial spectrum for this chemical class is possible without drifting off from the target. Development of the diarylquinolines class may represent a promising strategy for combating Gram-positive pathogens.
MK-5172, a Selective Inhibitor of Hepatitis C Virus NS3/4a Protease with Broad Activity across Genotypes and Resistant Variants
Authors: Summa Vincenzo , Ludmerer Steven W. , McCauley John A. , Fandozzi Christine , Burlein Christine , Claudio Giuliano , Coleman Paul J. , DiMuzio Jillian M. , Ferrara Marco , Di Filippo Marcello , Gates Adam T. , Graham Donald J. , Harper Steven , Hazuda Daria J. , McHale Carolyn , Monteagudo Edith , Pucci Vincenzo , Rowley Michael , Rudd Michael T. , Soriano Aileen , Stahlhut Mark W. , Vacca Joseph P. , Olsen David B. , Liverton Nigel J. , Carroll Steven S.
Published: May 2012

HCV NS3/4a protease inhibitors are proven therapeutic agents against chronic hepatitis C virus infection, with boceprevir and telaprevir having recently received regulatory approval as add-on therapy to pegylated interferon/ribavirin for patients harboring genotype 1 infections. Overcoming antiviral resistance, broad genotype coverage, and a convenient dosing regimen are important attributes for future agents to be used in combinations without interferon. In this communication, we report the preclinical profile of MK-5172, a novel P2-P4 quinoxaline macrocyclic NS3/4a protease inhibitor currently in clinical development. The compound demonstrates subnanomolar activity against a broad enzyme panel encompassing major hepatitis C virus (HCV) genotypes as well as variants resistant to earlier protease inhibitors. In replicon selections, MK-5172 exerted high selective pressure, which yielded few resistant colonies. In both rat and dog, MK-5172 demonstrates good plasma and liver exposures, with 24-h liver levels suggestive of once-daily dosing. When administered to HCV-infected chimpanzees harboring chronic gt1a or gt1b infections, MK-5172 suppressed viral load between 4 to 5 logs at a dose of 1 mg/kg of body weight twice daily (b.i.d.) for 7 days. Based on its preclinical profile, MK-5172 is anticipated to be broadly active against multiple HCV genotypes and clinically important resistance variants and highly suited for incorporation into newer all-oral regimens.
An Automated Image-Based Method for Rapid Analysis of Chlamydia Infection as a Tool for Screening Antichlamydial Agents
Authors: Osaka Ichie , Hills Jeffrey M. , Kieweg Sarah L. , Shinogle Heather E. , Moore David S. , Hefty P. Scott
Published: May 2012

A major limitation in the identification of novel antichlamydial compounds is the paucity of effective methods for large-scale compound screening. The immunofluorescence assay is the preferred approach for accurate quantification of the intracellular growth of
Chlamydia
. In this study, an immunofluorescence image-based method (termed image-based automated chlamydial identification and enumeration [iBAChIE]) was customized for fully automated quantification of
Chlamydia
infection using the freely available open-source image analysis software program CellProfiler and the complementary data exploration software program CellProfiler Analyst. The method yielded enumeration of different species and strains of
Chlamydia
highly comparably to the conventional manual methods while drastically reducing the analysis time. The inhibitory capability of established antichlamydial activity was also evaluated. Overall, these data support that iBAChIE is a highly effective tool for automated quantification of
Chlamydia
infection and assessment of antichlamydial activities of molecules. Furthermore, iBAChIE is expected to be amenable to high-throughput screening studies for inhibitory compounds and fluorescently labeled molecules to study host-pathogen interactions.
Inactivation of Mycobacterium tuberculosis
l
,
d
-Transpeptidase Ldt
Mt1
by Carbapenems and Cephalosporins
Authors: Dubée Vincent , Triboulet Sébastien , Mainardi Jean-Luc , Ethève-Quelquejeu Mélanie , Gutmann Laurent , Marie Arul , Dubost Lionel , Hugonnet Jean-Emmanuel , Arthur Michel
Published: May 2012

The structure of
Mycobacterium tuberculosis
peptidoglycan is atypical since it contains a majority of 3→3 cross-links synthesized by
l
,
d
-transpeptidases that replace 4→3 cross-links formed by the
d
,
d
-transpeptidase activity of classical penicillin-binding proteins. Carbapenems inactivate these
l
,
d
-transpeptidases, and meropenem combined with clavulanic acid is bactericidal against extensively drug-resistant
M. tuberculosis
. Here, we used mass spectrometry and stopped-flow fluorimetry to investigate the kinetics and mechanisms of inactivation of the prototypic
M. tuberculosis
l
,
d
-transpeptidase Ldt
Mt1
by carbapenems (meropenem, doripenem, imipenem, and ertapenem) and cephalosporins (cefotaxime, cephalothin, and ceftriaxone). Inactivation proceeded through noncovalent drug binding and acylation of the catalytic Cys of Ldt
Mt1
, which was eventually followed by hydrolysis of the resulting acylenzyme. Meropenem rapidly inhibited Ldt
Mt1
, with a binding rate constant of 0.08 μM
−1
min
−1
. The enzyme was unable to recover from this initial binding step since the dissociation rate constant of the noncovalent complex was low (<0.1 min
−1
) in comparison to the acylation rate constant (3.1 min
−1
). The covalent adduct resulting from enzyme acylation was stable, with a hydrolysis rate constant of 1.0 × 10
−3
min
−1
. Variations in the carbapenem side chains affected both the binding and acylation steps, ertapenem being the most efficient Ldt
Mt1
inactivator. Cephalosporins also formed covalent adducts with Ldt
Mt1
, although the acylation reaction was 7- to 1,000-fold slower and led to elimination of one of the drug side chains. Comparison of kinetic constants for drug binding, acylation, and acylenzyme hydrolysis indicates that carbapenems and cephems can both be tailored to optimize peptidoglycan synthesis inhibition in
M. tuberculosis
.
Facultative Sterol Uptake in an Ergosterol-Deficient Clinical Isolate of Candida glabrata Harboring a Missense Mutation in
ERG11
and Exhibiting Cross-Resistance to Azoles and Amphotericin B
Authors: Hull Claire M. , Parker Josie E. , Bader Oliver , Weig Michael , Gross Uwe , Warrilow Andrew G. S. , Kelly Diane E. , Kelly Steven L.
Published: May 2012

We identified a clinical isolate of
Candida glabrata
(CG156) exhibiting flocculent growth and cross-resistance to fluconazole (FLC), voriconazole (VRC), and amphotericin B (AMB), with MICs of >256, >256, and 32 μg ml
−1
, respectively. Sterol analysis using gas chromatography-mass spectrometry (GC-MS) revealed that CG156 was a sterol 14α-demethylase (Erg11p) mutant, wherein 14α-methylated intermediates (lanosterol was >80% of the total) were the only detectable sterols.
ERG11
sequencing indicated that CG156 harbored a single-amino-acid substitution (G315D) which nullified the function of native Erg11p. In heterologous expression studies using a doxycycline-regulatable
Saccharomyces cerevisiae erg11
strain, wild-type
C. glabrata
Erg11p fully complemented the function of
S. cerevisiae
sterol 14α-demethylase, restoring growth and ergosterol synthesis in recombinant yeast; mutated CG156 Erg11p did not. CG156 was culturable using sterol-free, glucose-containing yeast minimal medium (
glc
YM). However, when grown on sterol-supplemented
glc
YM (with ergosta 7,22-dienol, ergosterol, cholestanol, cholesterol, Δ
7
-cholestenol, or desmosterol), CG156 cultures exhibited shorter lag phases, reached higher cell densities, and showed alterations in cellular sterol composition. Unlike comparator isolates (harboring wild-type
ERG11
) that became less sensitive to FLC and VRC when cultured on sterol-supplemented
glc
YM, facultative sterol uptake by CG156 did not affect its azole-resistant phenotype. Conversely, CG156 grown using
glc
YM with ergosterol (or with ergosta 7,22-dienol) showed increased sensitivity to AMB; CG156 grown using
glc
YM with cholesterol (or with cholestanol) became more resistant (MICs of 2 and >64 μg AMB ml
−1
, respectively). Our results provide insights into the consequences of sterol uptake and metabolism on growth and antifungal resistance in
C. glabrata
.
An Integrated Approach for Identification and Target Validation of Antifungal Compounds Active against Erg11p
Authors: Hoepfner Dominic , Karkare Shantanu , Helliwell Stephen B. , Pfeifer Martin , Trunzer Markus , De Bonnechose Sophie , Zimmerlin Alfred , Tao Jianshi , Richie Daryl , Hofmann Andreas , Reinker Stefan , Frederiksen Mathias , Movva N. Rao , Porter Jeffrey A. , Ryder Neil S. , Parker Christian N.
Published: May 2012

Systemic life-threatening fungal infections represent a significant unmet medical need. Cell-based, phenotypic screening can be an effective means of discovering potential novel antifungal compounds, but it does not address target identification, normally required for compound optimization by medicinal chemistry. Here, we demonstrate a combination of screening, genetic, and biochemical approaches to identify and characterize novel antifungal compounds. We isolated a set of novel non-azole antifungal compounds for which no target or mechanism of action is known, using a screen for inhibition of
Saccharomyces cerevisiae
proliferation. Haploinsufficiency profiling of these compounds in
S. cerevisiae
suggests that they target Erg11p, a cytochrome P450 family member, which is the target of azoles. Consistent with this, metabolic profiling in
S. cerevisiae
revealed a buildup of the metabolic intermediates prior to Erg11p activity, following compound treatment. Further, human cytochrome P450 is also inhibited in
in vitro
assays by these compounds. We modeled the Erg11p protein based on the human CYP51 crystal structure, and
in silico
docking of these compounds suggests that they interact with the heme center in a manner similar to that of azoles. Consistent with these docking observations,
Candida
strains carrying azole-resistant alleles of
ERG11
are also resistant to the compounds in this study. Thus, we have identified non-azole Erg11p inhibitors, using a systematic approach for ligand and target characterization.
Antitubercular Activity of Disulfiram, an Antialcoholism Drug, against Multidrug- and Extensively Drug-Resistant Mycobacterium tuberculosis Isolates
Authors: Horita Yasuhiro , Takii Takemasa , Yagi Tetsuya , Ogawa Kenji , Fujiwara Nagatoshi , Inagaki Emi , Kremer Laurent , Sato Yasuo , Kuroishi Ryuji , Lee YooSa , Makino Toshiaki , Mizukami Hajime , Hasegawa Tomohiro , Yamamoto Ryuji , Onozaki Kikuo
Published: May 2012

The antimycobacterial activities of disulfiram (DSF) and diethyldithiocarbamate (DDC) against multidrug- and extensively drug-resistant tuberculosis (MDR/XDR-TB) clinical isolates were evaluatedin vitro. Both DSF and DDC exhibited potent antitubercular activities against 42 clinical isolates ofM. tuberculosis, including MDR/XDR-TB strains. Moreover, DSF showed remarkable bactericidal activityex vivoandin vivo. Therefore, DSF might be a drug repurposed for the treatment of MDR/XDR-TB.
Different Biosynthetic Pathways to Fosfomycin in Pseudomonas syringae and Streptomyces Species
Authors: Kim Seung Young , Ju Kou-San , Metcalf William W. , Evans Bradley S. , Kuzuyama Tomohisa , van der Donk Wilfred A.
Published: May 2012

Fosfomycin is a wide-spectrum antibiotic that is used clinically to treat acute cystitis in the United States. The compound is produced by several strains of streptomycetes and pseudomonads. We sequenced the biosynthetic gene cluster responsible for fosfomycin production in
Pseudomonas syringae
PB-5123. Surprisingly, the biosynthetic pathway in this organism is very different from that in
Streptomyces fradiae
and
Streptomyces wedmorensis
. The pathways share the first and last steps, involving conversion of phosphoenolpyruvate to phosphonopyruvate (PnPy) and 2-hydroxypropylphosphonate (2-HPP) to fosfomycin, respectively, but the enzymes converting PnPy to 2-HPP are different. The genome of
P. syringae
PB-5123 lacks a gene encoding the PnPy decarboxylase found in the
Streptomyces
strains. Instead, it contains a gene coding for a citrate synthase-like enzyme, Psf2, homologous to the proteins that add an acetyl group to PnPy in the biosynthesis of FR-900098 and phosphinothricin. Heterologous expression and purification of Psf2 followed by activity assays confirmed the proposed activity of Psf2. Furthermore, heterologous production of fosfomycin in
Pseudomonas aeruginosa
from a fosmid encoding the fosfomycin biosynthetic cluster from
P. syringae
PB-5123 confirmed that the gene cluster is functional. Therefore, two different pathways have evolved to produce this highly potent antimicrobial agent.
Implication of Antigenic Conversion of Helicobacter pylori Lipopolysaccharides That Involve Interaction with Surfactant Protein D
Authors: Yokota Shin-ichi , Amano Ken-ichi , Nishitani Chiaki , Ariki Shigeru , Kuroki Yoshio , Fujii Nobuhiro
Published: May 2012

We propose two antigenic types of
Helicobacter pylori
lipopolysaccharides (LPS): highly antigenic epitope-carrying LPS (HA-LPS) and weakly antigenic epitope-carrying LPS (WA-LPS) based on human serum reactivity. Strains carrying WA-LPS are highly prevalent in isolates from gastric cancer patients. WA-LPS exhibits more potent biological activities compared to HA-LPS, namely, upregulation of Toll-like receptor 4 (TLR4) expression and induction of enhanced epithelial cell proliferation. The results of competitive binding assays using monosaccharides and methylglycosides, as well as binding assays using glycosidase-treated LPS, suggested that β-linked
N
-acetyl-
d
-glucosamine and β-linked
d
-galactose residues largely contributed to the highly antigenic epitope and the weakly antigenic epitope, respectively. WA-LPS exhibited greater binding activity to surfactant protein D (SP-D) in a Ca
2+
-dependent manner, and this interaction was inhibited by methyl-β-
d
-galactoside. The biological activities of WA-LPS were markedly enhanced by the addition of SP-D. Lines of evidence suggested that removal of β-
N
-acetyl-
d
-glucosamine residue, which comprises the highly antigenic epitope, results in exposure of the weakly antigenic epitope. The weakly antigenic epitope interacted preferentially with SP-D, and SP-D enhanced the biological activity of WA-LPS.
SURFACE PROPERTIES OF THE IN SITU FORMED CERAMICS REINFORCED COMPOSITE COATINGS ON TI-3AL-2V ALLOYS
Authors: LIU PENG , GUO WEI , HU DAKUI , LUO HUI , ZHANG YUANBIN
Published: May 2012

The synthesis of hard composite coating on titanium alloy by laser cladding of Al/Fe/Ni+C/Si3N4 pre-placed powders has been investigated in detail. SEM result indicated that a composite coating with metallurgical joint to the substrate was formed. XRD result indicated that the composite coating mainly consisted of γ- (Fe, Ni) , FeAl , Ti3Al , TiC , TiNi , TiC0.3N0.7 , Ti2N , SiC , Ti5Si3 and TiNi . Compared with Ti-3Al-2V substrate, an improvement of the micro-hardness and the wear resistance was observed for this composite coating.
STUDY OF THE SYNTHESIS AND FIELD EMISSION CHARACTERISTICS OF ONE-DIMENSIONAL GaN NANOSTRUCTURES
Authors: LI ENLING , ZHAO TAO , ZHAO DANNA , CUI ZHEN , LIU MANCANG
Published: May 2012

The chemical vapor deposition (CVD) process has been used to synthesize gallium nitride (GaN) nanostructures using Pt -coated n-type Si (100) as the substrate, and NH 3 gas and Ga 2 O 3 powder as the reaction agents. The surface morphologies of the prepared GaN nanostructures obtained by field emission scanning electron microscopy (FE-SEM) show a large number of GaN nanowires and nanorods on the Si substrates. The synthesized nanostructures are hexagonal as determined from XRD analysis and show a turn-on field of 5 v/μm at 10 μA/cm2.
STRUCTURAL AND OPTICAL CHARACTERIZATION OF CdS:Fe THIN FILMS PREPARED BY FLASH EVAPORATION METHOD
Authors: DIZAJI H. R. , GHASEMIAN M. , EHSANI M. H.
Published: May 2012

CdS thin layers of 250 nm thick doped with zero, 0.1, 0.2 and 0.3 weight percents iron were deposited on glass substrates by modified flash evaporation technique in vacuum at the pressure of 5 × 10−6 mbar. The structure of the films was investigated by X-ray diffractometry. It was revealed that the films had hexagonal structure with (002) preferred orientation. Field emission scanning electron microscopy (FESEM) was employed to study the surface morphology of the prepared samples. It was found from FESEM images that the Fe -doped CdS film showed more surface uniformity. Optical absorption data of the films were used to measure the band gap of the films. It was found that the band gap of the samples decreased upon increasing the Iron concentration. Photoluminescence (PL) spectra of the CdS:Fe thin films were used to study most prominent excitation peaks within the energy range (1.6–2.6 eV). The variation in peak energy was observed upon increasing the Fe content in the films.
BAND ALIGNMENT AND ATOM SEGREGATION OF LaYbO3 FILMS ON SILICON
Authors: SU WEI-TAO , HUO DE-XUAN , LI BIN
Published: May 2012

Ternary rare earth oxides are expected to be more promising high-k dielectric materials than conventional binary rare earth oxides due to higher band gap, higher permittivity and good interfacial stability. In the present study, the band alignment and atom thermal diffusion of LaYbO3 , a new ternary rare earth oxide, are studied by X-ray photoelectron spectrum (XPS) and angle-resolved XPS, respectively. The band gap value for LaYbO3 crystalline film rises to 6.7 eV compared with 6.2 eV for amorphous film. Valence (ΔEv) and conduction band (ΔEc) offset are ΔEv = 3.5 eV, ΔEc = 1.6 eV for the amorphous film and ΔEv = 3.3 eV, ΔEc = 2.3 eV for the crystalline film. From elemental depth profile through high-k layer and silicon substrate, it is shown that La atom tends to diffuse into silicon substrate and piles up at oxide/silicon interface at high annealing temperature ~1000°C.
DEVELOPMENT OF PLATINUM(IV) COMPLEXES AS ANTICANCER PRODRUGS: THE STORY SO FAR
Authors: WONG DANIEL YUAN QIANG , ANG WEE HAN
Published: May 2012

The serendipitous discovery of the antitumor properties of cisplatin by Barnett Rosenberg some forty years ago brought about a paradigm shift in the field of medicinal chemistry and challenged conventional thinking regarding the role of potentially toxic heavy metals in drugs. Platinum(II)-based anticancer drugs have since become some of the most effective and widely-used drugs in a clinician's arsenal and have saved countless lives. However, they are limited by high toxicity, severe side-effects and the incidence of drug resistance. In recent years, attention has shifted to stable platinum(IV) complexes as anticancer prodrugs. By exploiting the unique chemical and structural attributes of their scaffolds, these platinum(IV) prodrugs offer new strategies of targeting and killing cancer cells. This review summarizes the development of anticancer platinum(IV) prodrugs to date and some of the exciting strategies that utilise the platinum(IV) construct as targeted chemotherapeutic agents against cancer.
Structure and Regulation of Soluble Guanylate Cyclase
Authors: Derbyshire Emily R. , Marletta Michael A.
Published: May 2012

Nitric oxide (NO) is an essential signaling molecule in biological systems. In mammals, the diatomic gas is critical to the cyclic guanosine monophosphate (cGMP) pathway as it functions as the primary activator of soluble guanylate cyclase (sGC). NO is synthesized from l-arginine and oxygen (O2) by the enzyme nitric oxide synthase (NOS). Once produced, NO rapidly diffuses across cell membranes and binds to the heme cofactor of sGC. sGC forms a stable complex with NO and carbon monoxide (CO), but not with O2. The binding of NO to sGC leads to significant increases in cGMP levels. The second messenger then directly modulates phosphodiesterases (PDEs), ion-gated channels, or cGMP-dependent protein kinases to regulate physiological functions, including vasodilation, platelet aggregation, and neurotransmission. Many studies are focused on elucidating the molecular mechanism of sGC activation and deactivation with a goal of therapeutic intervention in diseases involving the NO/cGMP-signaling pathway. This review summarizes the current understanding of sGC structure and regulation as well as recent developments in NO signaling.
Ubiquitin-Binding Proteins: Decoders of Ubiquitin-Mediated Cellular Functions
Authors: Husnjak Koraljka , Dikic Ivan
Published: May 2012

Ubiquitin acts as a versatile cellular signal that controls a wide range of biological processes including protein degradation, DNA repair, endocytosis, autophagy, transcription, immunity, and inflammation. The specificity of ubiquitin signaling is achieved by alternative conjugation signals (monoubiquitin and ubiquitin chains) and interactions with ubiquitin-binding proteins (known as ubiquitin receptors) that decode ubiquitinated target signals into biochemical cascades in the cell. Herein, we review the current knowledge pertaining to the structural and functional features of ubiquitin-binding proteins and the mechanisms by which they recognize various types of ubiquitin topologies. The combinatorial use of diverse ubiquitin-binding domains (UBDs) in full-length proteins, selective recognition of chains with distinct linkages and length, and posttranslational modifications of ubiquitin receptors or multivalent interactions within protein complexes illustrate a few mechanisms by which a circuitry of signaling networks can be rewired by ubiquitin-binding proteins to control cellular functions in vivo.
RNA Polymerase II Elongation Control
Authors: Zhou Qiang , Li Tiandao , Price David H.
Published: May 2012

Regulation of the elongation phase of transcription by RNA polymerase II (Pol II) is utilized extensively to generate the pattern of mRNAs needed to specify cell types and to respond to environmental changes. After Pol II initiates, negative elongation factors cause it to pause in a promoter proximal position. These polymerases are poised to respond to the positive transcription elongation factor P-TEFb, and then enter productive elongation only under the appropriate set of signals to generate full-length properly processed mRNAs. Recent global analyses of Pol II and elongation factors, mechanisms that regulate P-TEFb involving the 7SK small nuclear ribonucleoprotein (snRNP), factors that control both the negative and positive elongation properties of Pol II, and the mRNA processing events that are coupled with elongation are discussed.
Regulation of Glucose Transporter Translocation in Health and Diabetes
Authors: Bogan Jonathan S.
Published: May 2012

To enhance glucose uptake into muscle and fat cells, insulin stimulates the translocation of GLUT4 glucose transporters from intracellular membranes to the cell surface. This response requires the intersection of insulin signaling and vesicle trafficking pathways, and it is compromised in the setting of overnutrition to cause insulin resistance. Insulin signals through AS160/Tbc1D4 and Tbc1D1 to modulate Rab GTPases and through the Rho GTPase TC10α to act on other targets. In unstimulated cells, GLUT4 is incorporated into specialized storage vesicles containing IRAP, LRP1, sortilin, and VAMP2, which are sequestered by TUG, Ubc9, and other proteins. Insulin mobilizes these vesicles directly to the plasma membrane, and it modulates the trafficking itinerary so that cargo recycles from endosomes during ongoing insulin exposure. Knowledge of how signaling and trafficking pathways are coordinated will be essential to understanding the pathogenesis of diabetes and the metabolic syndrome and may also inform a wide range of other physiologies.
Discovery, Biosynthesis, and Engineering of Lantipeptides
Authors: Knerr Patrick J. , van der Donk Wilfred A.
Published: May 2012

Aided by genome-mining strategies, knowledge of the prevalence and diversity of ribosomally synthesized natural products (RNPs) is rapidly increasing. Among these are the lantipeptides, posttranslationally modified peptides containing characteristic thioether cross-links imperative for bioactivity and stability. Though this family was once thought to be a limited class of antimicrobial compounds produced by gram-positive bacteria, new insights have revealed a much larger diversity of activity, structure, biosynthetic machinery, and producing organisms than previously appreciated. Detailed investigation of the enzymes responsible for installing the posttranslational modifications has resulted in improved in vivo and in vitro engineering systems focusing on enhancement of the therapeutic potential of these compounds. Although dozens of new lantipeptides have been isolated in recent years, bioinformatic analyses indicate that many hundreds more await discovery owing to the widespread frequency of lantipeptide biosynthetic machinery in bacterial genomes.
Toward the Single-Hour High-Quality Genome
Authors: Ståhl Patrik L. , Lundeberg Joakim
Published: May 2012

Today, resequencing of a human genome can be performed in approximately a week using a single instrument. Thanks to a steady logarithmic rate of increase in performance for DNA sequencing platforms over the past seven years, DNA sequencing is one of the fastest developing technology fields. As the process becomes faster, it opens up possibilities within health care, diagnostics, and entirely new fields of research. Immediate genetic characterization of contagious outbreaks has been exemplified, and with such applications for the direct benefit of human health, expectations of future sensitive, rapid, high-throughput, and cost-effective technologies are steadily growing. Simultaneously, some of the limitations of a rapidly growing field have become apparent, and questions regarding the quality of some of the data deposited into databases have been raised. A human genome sequenced in only an hour is likely to become a reality in the future, but its definition may not be as certain.
Structure Unifies the Viral Universe
Authors: Abrescia Nicola G.A. , Bamford Dennis H. , Grimes Jonathan M. , Stuart David I.
Published: May 2012

Is it possible to meaningfully comprehend the diversity of the viral world? We propose that it is. This is based on the observation that, although there is immense genomic variation, every infective virion is restricted by strict constraints in structure space (i.e., there are a limited number of ways to fold a protein chain, and only a small subset of these have the potential to construct a virion, the hallmark of a virus). We have previously suggested the use of structure for the higher-order classification of viruses, where genomic similarities are no longer observable. Here, we summarize the arguments behind this proposal, describe the current status of structural work, highlighting its power to infer common ancestry, and discuss the limitations and obstacles ahead of us. We also reflect on the future opportunities for a more concerted effort to provide high-throughput methods to facilitate the large-scale sampling of the virosphere.
Ubiquitin-Like Proteins
Authors: van der Veen Annemarthe G. , Ploegh Hidde L.
Published: May 2012

The eukaryotic ubiquitin family encompasses nearly 20 proteins that are involved in the posttranslational modification of various macromolecules. The ubiquitin-like proteins (UBLs) that are part of this family adopt the β-grasp fold that is characteristic of its founding member ubiquitin (Ub). Although structurally related, UBLs regulate a strikingly diverse set of cellular processes, including nuclear transport, proteolysis, translation, autophagy, and antiviral pathways. New UBL substrates continue to be identified and further expand the functional diversity of UBL pathways in cellular homeostasis and physiology. Here, we review recent findings on such novel substrates, mechanisms, and functions of UBLs.
Development of an Fc-Enhanced Anti–B7-H3 Monoclonal Antibody with Potent Antitumor Activity
Authors: Loo Deryk , Alderson Ralph F. , Chen Francine Z. , Huang Ling , Zhang Wenjun , Gorlatov Sergey , Burke Steve , Ciccarone Valentina , Li Hua , Yang Yinhua , Son Tom , Chen Yan , Easton Ann N. , Li Jonathan C. , Rillema Jill R. , Licea Monica , Fieger Claudia , Liang Tony W. , Mather Jennie P. , Koenig Scott , Stewart Stanford J. , Johnson Syd , Bonvini Ezio , Moore Paul A.
Published: May 2012

Purpose: The goal of this research was to harness a monoclonal antibody (mAb) discovery platform to identify cell-surface antigens highly expressed on cancer and develop, through Fc optimization, potent mAb therapies toward these tumor-specific antigens.

Experimental Design: Fifty independent mAbs targeting the cell-surface immunoregulatory B7-H3 protein were obtained through independent intact cell-based immunizations using human tissue progenitor cells, cancer cell lines, or cell lines displaying cancer stem cell properties. Binding studies revealed this natively reactive B7-H3 mAb panel to bind a range of independent B7-H3 epitopes. Immunohistochemical analyses showed that a subset displayed strong reactivity to a broad range of human cancers while exhibiting limited binding to normal human tissues. A B7-H3 mAb displaying exquisite tumor/normal differential binding was selected for humanization and incorporation of an Fc domain modified to enhance effector-mediated antitumor function via increased affinity for the activating receptor CD16A and decreased binding to the inhibitory receptor CD32B.

Results: MGA271, the resulting engineered anti–B7-H3 mAb, mediates potent antibody-dependent cellular cytotoxicity against a broad range of tumor cell types. Furthermore, in human CD16A-bearing transgenic mice, MGA271 exhibited potent antitumor activity in B7-H3–expressing xenograft models of renal cell and bladder carcinoma. Toxicology studies carried out in cynomolgus monkeys revealed no significant test article-related safety findings.

Conclusions: This data supports evaluation of MGA271 clinical utility in B7-H3–expressing cancer, while validating a combination of a nontarget biased approach of intact cell immunizations and immunohistochemistry to identify novel cancer antigens with Fc-based mAb engineering to enable potent antitumor activity. Clin Cancer Res; 18(14); 3834–45. ©2012 AACR.
Antiplatelet Drug Response Status Does Not Predict Recurrent Ischemic Events in Stable Cardiovascular Patients
Authors: Reny Jean-Luc , Berdagué Philippe , Poncet Antoine , Barazer Isabelle , Nolli Séverine , Fabbro-Peray Pascale , Schved Jean-François , Bounameaux Henri , Mach François , de Moerloose Philippe , Fontana Pierre
Published: May 2012

Background—

The biological response to antiplatelet drugs has repeatedly been shown to predict the recurrence of major adverse cardiovascular events (MACEs). However, most studies involved coronary artery disease patients with recent vessel injury shortly after the initiation of antiplatelet therapy. Data on stable cardiovascular patients are scarce, and the added predictive value of specific assays (the vasodilator phosphoprotein assay for the clopidogrel response and serum thromboxane B2 for the aspirin response) and aggregation-based assays relative to common predictors has rarely been addressed.

Methods and Results—

Stable cardiovascular outpatients participating in the Antiplatelet Drug Resistances and Ischemic Events (ADRIE) study (n=771) were tested twice, at 2 separate visits, with specific and aggregation-based assays. Follow-up lasted 3 years, and <1% of patients were lost to follow-up. MACEs were adjudicated by an independent committee. Multivariate survival analyses included relevant variables identified in univariate analysis and platelet function test results. The C-index was used to express the prognostic value of various multivariate models. MACEs, the primary end point, occurred in 16% of patients. Hypertension, smoking, older age, and elevated low-density lipoprotein cholesterol were predictive of MACE recurrence, with a C-index of 0.63 (
P
<0.001). Neither the specific nor the aggregation-based assays added significant predictive value for the primary end point.

Conclusions—

Biological antiplatelet drug responsiveness, measured with specific or aggregation-based assays, has no incremental predictive value over common cardiovascular risk factors for MACE recurrence in stable cardiovascular outpatients. These results do not support platelet function testing for MACE risk evaluation in stable cardiovascular patients.

Clinical Trial Registration—

URL:
http://www.clinicaltrials.gov
. Unique identifier: NCT00501423.
The United States Registry for Fibromuscular Dysplasia
Authors: Olin Jeffrey W. , Froehlich James , Gu Xiaokui , Bacharach J. Michael , Eagle Kim , Gray Bruce H. , Jaff Michael R. , Kim Esther S.H. , Mace Pam , Matsumoto Alan H. , McBane Robert D. , Kline-Rogers Eva , White Christopher J. , Gornik Heather L.
Published: May 2012

Background—

Fibromuscular dysplasia (FMD), a noninflammatory disease of medium-size arteries, may lead to stenosis, occlusion, dissection, and/or aneurysm. There has been little progress in understanding the epidemiology, pathogenesis, and outcomes since its first description in 1938.

Methods and Results—

Clinical features, presenting symptoms, and vascular events are reviewed for the first 447 patients enrolled in a national FMD registry from 9 US sites. Vascular beds were imaged selectively based on clinical presentation and local practice. The majority of patients were female (91%) with a mean age at diagnosis of 51.9 (SD 13.4 years; range, 5–83 years). Hypertension, headache, and pulsatile tinnitus were the most common presenting symptoms of the disease. Self-reported family history of stroke (53.5%), aneurysm (23.5%), and sudden death (19.8%) were common, but FMD in first- or second-degree relatives was reported only in 7.3%. FMD was identified in the renal artery in 294 patients, extracranial carotid arteries in 251 patients, and vertebral arteries in 82 patients. A past or presenting history of vascular events were common: 19.2% of patients had a transient ischemic attack or stroke, 19.7% had experienced arterial dissection(s), and 17% of patients had an aneurysm(s). The most frequent indications for therapy were hypertension, aneurysm, and dissection.

Conclusions—

In this registry, FMD occurred primarily in middle-aged women, although it presents across the lifespan. Cerebrovascular FMD occurred as frequently as renal FMD. Although a significant proportion of FMD patients may present with a serious vascular event, many present with nonspecific symptoms and a subsequent delay in diagnosis.