bluuebunny/crossref_metadata_2025 huggingface dataset:
Predictive Modeling and Experimental Verification of Temperature and Concentration in Rapid Freeze Prototyping With Support Material
Authors: Bryant Frances D. , Leu Ming C.
Published: July 2009

Rapid freeze prototyping is a solid freeform fabrication method that uses water freezing into ice as the build material. Each layer of geometry is deposited and allowed to freeze before the next layer is added in order to additively create a three-dimensional ice part. A sacrificial support material is needed for the fabrication of complex ice parts. Identifying a suitable support material and understanding the interaction between the build and support materials is the motivation behind this study. A temperature prediction model and a concentration prediction model are presented. Experimental results have been obtained to validate these models.
Ideal SiC Schottky barrier diodes fabricated using refractory metal borides
Authors: Oder T. N. , Sutphin E. , Kummari R.
Published: July 2009

Several refractory metal borides were used as Schottky contacts to fabricate n-type 4H-SiC Schottky diodes. The boride contacts were deposited on SiC substrates held at 20 and 600 °C. Contacts deposited on substrates held at 600 °C produced better diodes with smaller ideality factors from 1.05 to 1.10, barrier heights from 0.94 to 1.15 eV, smaller leakage current densities at a reverse bias of 15 V, and smaller specific on-resistances compared to contacts deposited on substrates held at 20 °C, and these values remained essentially unchanged after annealing at 600 °C for 20 min. The Rutherford backscattering spectroscopy spectra of one of these boride contacts revealed a systematic decrease in oxygen with an increase in the deposition temperature. The improved electrical properties and thermal stability make these boride contacts attractive for high power and high temperature device applications.
Fabrication of high quality factor photonic crystal microcavities in InAsP∕InP membranes combining reactive ion beam etching and reactive ion etching
Authors: Martínez L. J. , Prieto I. , Alén B. , Postigo P. A.
Published: July 2009

The process of fabrication of high quality factor photonic crystal microcavities in slabs of InP with light emission at 1.5μm is reported. The process includes e-beam lithography, reactive ion beam etching with a CHF3∕N2 gas mixture, and reactive ion etching with a CH4∕H2 gas mixture and O2 cycling. An InGaAs sacrificial layer is removed by chemical wet etching in order to obtain the photonic crystal membrane. Microphotoluminescense measurements have been performed to assess the quality of the fabricated structures. Quality factors up to ≃30000 and laser emission with thresholds of excitation pump power around 34μW have been obtained.
Nondestructive nanoscale profile measurement on two-dimensional photonic crystal structure using differential confocal microscopy
Authors: Kuo Wen-Chuan , Juang Fu-Jay , Su Hong-Ren , Hsieh Mei-Li
Published: July 2009

In this study, the authors evaluated the effectiveness of using the nanometer depth sensitivity of differential confocal microscopy (DCM) to measure the surface profile of the two-dimensional (2D) photonic crystal structure. The depth of the micropore on the 2D hexagonal photonic crystal sample can be measured within 4.2nm resolution. The surface profile of the 2D photonic crystal structure on the photoresist can be obtained by the nondestructive and noncontact DCM method, and the results were comparable to those from the commercial atomic force microscope method.
Dry etch selectivity of a-C:H hardmasks for sub-65nm patterning applications
Authors: Padhi D. , Kim B. H. , Witty D.
Published: July 2009

Amorphous carbon (a-C:H) is widely used as a hardmask in semiconductor device manufacturing to enable patterning of sub-65nm features. Key criteria for a good hardmask include the ability to transfer patterns into underlayers with tightest dimension control. In order to achieve this goal, the hardmask film must possess superior etch selectivity during reactive ion etching of the underlayers. In this article, the authors show that etch selectivity of a-C:H hardmask (to underlayers) is directly related to its film density. Fourier transform infrared and composition data are analyzed to determine the aggregate bond energy per unit volume of hardmask. It is shown that for a-C:H films, this energy increases with density as a result of the bonding configurations, thereby explaining the correlation between etch selectivity and density.
Fabrication of all-metal field emitter arrays with controlled apex sizes by molding
Authors: Kirk E. , Tsujino S. , Vogel T. , Jefimovs K. , Gobrecht J. , Wrulich A.
Published: July 2009

The authors proposed a method to fabricate field emitter arrays with uniform apex diameters in tens of nanometer scale based on the molding technique and apply it to fabricate molybdenum field emitter arrays. Apex diameter equal to 23±5nm was observed in a 6×6 tip array by high-resolution scanning electron microscope. They also studied the field-emission characteristics in devices with gate electrodes fabricated on top of the arrays by a self-aligned process. In single-gate devices, emission current of up to 20μA per tip with negligible gate leak current was observed. The gate-fabrication process was extended to fabricate double-gated emitters. Further optimization of the fabrication process for higher emission current, together with metallurgical and lithographic methods, is discussed.
Design and fabrication of surface acoustic wave delay line for surface acoustic wave chemical-agent sensors
Authors: Zhao Yigui , Liu Ming , Li Jingjing , Niu Jiebin , Li Dongmei
Published: July 2009

This article presents a method for designing and fabricating a surface acoustic wave (SAW) delay line for chemical-agent sensors. To improve the frequency stability and detection sensitivity, the authors designed and fabricated a SAW dual delay line with electrode-width control/single-phase unidirectional transducer and single-mode selection capability. Electron-beam direct writing lithography, x-ray lithography, and metal lift-off are applied to the fabrication of a SAW delay line with a submicron feature size. The experimental results are approximately in agreement with the design goals.
Inductively coupled plasma etching of GaAs suspended photonic crystal cavities
Authors: Braive R. , Le Gratiet L. , Guilet S. , Patriarche G. , Lemaître A. , Beveratos A. , Robert-Philip I. , Sagnes I.
Published: July 2009

The authors studied the dry-etching process by chlorine-based inductively coupled plasma for fabricating GaAs suspended photonic crystal cavities. To achieve low optical loss in such resonators, the photonic crystal holes must demonstrate simultaneously smooth sidewalls and good verticality. The influence of various parameters of the inductively coupled plasma process was investigated: a systematic analysis is provided on the dependency of hole sidewall roughness and shape on the process parameters such as gas mixture, etching power, pressure, and rf bias. The authors show that a combination of high pressure, high bias, and high etching power in an inductively coupled plasma with a Cl2/N2 chemistry is beneficial for achieving straight and smooth sidewalls, and wall tilt of less than 4° was obtained.
X-ray photoelectron spectroscopy characterization of aminosilane anchored to ZnO nanorod arrays grown by an aqueous solution method with microwave-assisted heating
Authors: Ogata K. , Koike K. , Sasa S. , Inoue M. , Yano M.
Published: July 2009

An intermediate for immobilizing biofunctional molecules, 3-aminopropyltrimethoxysilane (APTMS) was anchored to ZnO nanorod arrays which had been grown by an aqueous solution method with microwave-assisted heating on a-plane sapphire substrates. X-ray photoelectron spectroscopy analysis revealed that the quantity of APTMS anchored on the ZnO nanorod arrays was more than that on a flat ZnO layer. Also, annealing of the APTMS anchored to ZnO nanorods at 500°C showed that the amino groups were disappeared while Si atoms remained after the annealing probably due to strong Si–O bonding.
Investigation of etching two-dimensional microhole lattice array on lithium niobate with focused ion beam for fabricating photonic crystals
Authors: Xu Xuefeng , Yan Sha , Xue Jianming , Wang Yugang , Wang Keming , Wang Xuelin
Published: July 2009

Lithium niobate (LN) is a widely used artificial optic-electronic crystal. A LN surface is an attractive substrate for the fabrication of photonic crystals (PhCs) in order to form useful optical devices. In this work, two-dimensional microhole lattice arrays with specified structure parameters were fabricated on a LN substrate by means of focused ion beam (FIB) etching. The physical and geometrical reasons for the formation of a nonideal hole shape and the depth limitation are analyzed. The authors have mainly discussed the effect of redeposition and presented equations of depth change tendency and change rate. The influence of the aberration in the hole shape on the PhC’s transmission spectrum is also estimated. Insulator enhanced etching is implemented in order to get better quasicolumn holes, and it is partly effective. Their work shows that FIB is a simple way to etch a hole on LN, but it is still necessary to make technical improvements to the process in order to obtain a better hole shape for PhC applications.
Fabrication of ZnO nanorods by pulsed Nd:YAG laser ablation deposition
Authors: Shen Yiqun , Xu Ning , Lai Jushui , Sun Jian , Wu Jiada , Ying Zhifeng , Okada Tatsuo
Published: July 2009

ZnO nanorods were fabricated on Si (100) substrate by pulsed laser ablation of ZnO target with background O2 gas. Nd:YAG laser with wavelength of 532 nm was used as laser source. Field emitted scanning electron microscopy, x-ray diffraction, and Raman spectra were applied to characterize the surface morphologies and crystalline structures of the as-deposited ZnO nanorods. Photoluminescence (PL) was carried out to attain the optical properties of the as-deposited ZnO nanorods. It was found that ZnO nanorods have good crystallinity and sound optical properties. Their PL spectra with the strong and sharp ultraviolet peak were observed at room and low temperatures.
Enhanced resolution of poly(methyl methacrylate) electron resist by thermal processing
Authors: Arjmandi Nima , Lagae Liesbet , Borghs Gustaaf
Published: July 2009

Granular nanostructure of electron beam resist had limited the ultimate resolution of electron beam lithography. The authors report a thermal process to achieve a uniform and homogeneous amorphous thin film of polymethyl methacrylate electron resist. This thermal process consists of a short time-high temperature backing process in addition to precisely optimized development process conditions. Using this novel process, they patterned arrays of holes with diameter smaller than 5 nm and line edge roughness and surface roughness of the resist reduced to 1 nm and 100 pm, respectively. In addition, etch resistance of the resist verified and the resist pattern transferred to a metal thin film.
Chemical effect of dry and wet cleaning of the Ru protective layer of the extreme ultraviolet lithography reflector
Authors: Belau Leonid , Park Jeong Y. , Liang Ted , Seo Hyungtak , Somorjai Gabor A.
Published: July 2009

The authors report the chemical influence of cleaning of the Ru capping layer on the extreme ultraviolet (EUV) reflector surface. The cleaning of EUV reflector to remove the contamination particles has two requirements: to prevent corrosion and etching of the reflector surface and to maintain the reflectivity functionality of the reflector after the corrosive cleaning processes. Two main approaches for EUV reflector cleaning, wet chemical treatments [sulfuric acid and hydrogen peroxide mixture (SPM), ozonated water, and ozonated hydrogen peroxide] and dry cleaning (oxygen plasma and UV/ozone treatment), were tested. The changes in surface morphology and roughness were characterized using scanning electron microscopy and atomic force microscopy, while the surface etching and change of oxidation states were probed with x-ray photoelectron spectroscopy. Significant surface oxidation of the Ru capping layer was observed after oxygen plasma and UV/ozone treatment, while the oxidation is unnoticeable after SPM treatment. Based on these surface studies, the authors found that SPM treatment exhibits the minimal corrosive interactions with Ru capping layer. They address the molecular mechanism of corrosive gas and liquid-phase chemical interaction with the surface of Ru capping layer on the EUV reflector.
Evaluation of extreme-ultraviolet lithography mask absorber pattern on multilayer phase defect using extreme-ultraviolet microscope
Authors: Hamamoto K. , Sakaya N. , Hosoya M. , Kureishi M. , Ohkubo R. , Shoki T. , Nagarekawa O. , Kishimoto J. , Watanabe T. , Kinoshita H.
Published: July 2009

This article concerns the observation of phase defects in an extreme-ultraviolet lithography (EUVL) mask with an extreme-ultraviolet (EUV) microscope developed by the University of Hyogo. The influence of phase defects in a multilayer blank with an absorber pattern on critical dimension was examined. The test mask had line-shaped, programed phase defects at various places relative to the absorber lines. Since the defects were as high as 12 nm, the absorber pattern had a considerable influence on them. In places where a line defect crossed the absorber pattern, the change in critical dimension was proportional to the size of the defect. The experimental results agree well with exposure results obtained using the same mask. They demonstrate that an EUV microscope is a promising tool for evaluating finished EUVL masks and multilayer mask blanks and can eliminate the need for replication tests with an exposure tool.
Escherichia coli
O157:H7 Strains That Persist in Feedlot Cattle Are Genetically Related and Demonstrate an Enhanced Ability To Adhere to Intestinal Epithelial Cells
Authors: Carlson Brandon A. , Nightingale Kendra K. , Mason Gary L. , Ruby John R. , Choat W. Travis , Loneragan Guy H. , Smith Gary C. , Sofos John N. , Belk Keith E.
Published: July 2009

A longitudinal study was conducted to investigate the nature of
Escherichia coli
O157:H7 colonization of feedlot cattle over the final 100 to 110 days of finishing. Rectal fecal grab samples were collected from an initial sample population of 788 steers every 20 to 22 days and microbiologically analyzed to detect
E. coli
O157:H7. The identities of presumptive colonies were confirmed using a multiplex PCR assay that screened for gene fragments unique to
E. coli
O157:H7 (
rfbE
and
fliC
h7
) and other key virulence genes (
eae
,
stx
1
, and
stx
2
). Animals were classified as having persistent shedding (PS), transient shedding (TS), or nonshedding (NS) status if they consecutively shed the same
E. coli
O157:H7 genotype (based on the multiplex PCR profile), exhibited variable
E. coli
O157 shedding, or never shed morphologically typical
E. coli
O157, respectively. Overall, 1.0% and 1.4% of steers were classified as PS and NS animals, respectively. Characterization of 132
E. coli
O157:H7 isolates from PS and TS animals by pulsed-field gel electrophoresis (PFGE) typing yielded 32 unique PFGE types. One predominant PFGE type accounted for 53% of all isolates characterized and persisted in cattle throughout the study. Isolates belonging to this predominant and persistent PFGE type demonstrated an enhanced (
P
< 0.0001) ability to adhere to Caco-2 human intestinal epithelial cells compared to isolates belonging to less common PFGE types but exhibited equal virulence expression. Interestingly, the attachment efficacy decreased as the genetic divergence from the predominant and persistent subtype increased. Our data support the hypothesis that certain
E. coli
O157:H7 strains persist in feedlot cattle, which may be partially explained by an enhanced ability to colonize the intestinal epithelium.
Genetic Engineering of
Enterobacter asburiae
Strain JDR-1 for Efficient Production of Ethanol from Hemicellulose Hydrolysates
Authors: Bi Changhao , Zhang Xueli , Ingram Lonnie O. , Preston James F.
Published: July 2009

Dilute acid pretreatment is an established method for hydrolyzing the methylglucuronoxylans of hemicellulose to release fermentable xylose. In addition to xylose, this process releases the aldouronate methylglucuronoxylose, which cannot be metabolized by current ethanologenic biocatalysts.
Enterobacter asburiae
JDR-1, isolated from colonized wood, was found to efficiently ferment both methylglucuronoxylose and xylose in acid hydrolysates of sweet gum xylan, producing predominantly ethanol and acetate. Transformation of
E. asburiae
JDR-1 with pLOI555 or pLOI297, each containing the PET operon containing pyruvate decarboxylase (
pdc
) and alcohol dehydrogenase B (
adhB
) genes derived from
Zymomonas mobilis
, replaced mixed-acid fermentation with homoethanol fermentation. Deletion of the pyruvate formate lyase (
pflB
) gene further increased the ethanol yield, resulting in a stable
E. asburiae
E1(pLOI555) strain that efficiently utilized both xylose and methylglucuronoxylose in dilute acid hydrolysates of sweet gum xylan. Ethanol was produced from xylan hydrolysate by
E. asburiae
E1(pLOI555) with a yield that was 99% of the theoretical maximum yield and at a rate of 0.11 g ethanol/g (dry weight) cells/h, which was 1.57 times the yield and 1.48 times the rate obtained with the ethanologenic strain
Escherichia coli
KO11. This engineered derivative of
E. asburiae
JDR-1 that is able to ferment the predominant hexoses and pentoses derived from both hemicellulose and cellulose fractions is a promising subject for development as an ethanologenic biocatalyst for production of fuels and chemicals from agricultural residues and energy crops.
The Longin Domain Regulates the Steady-State Dynamics of Sec22 inPlasmodium falciparum
Authors: Ayong Lawrence , Raghavan Avanthi , Schneider Timothy G. , Taraschi Theodore F. , Fidock David A. , Chakrabarti Debopam
Published: July 2009

The specificity of vesicle-mediated transport is largely regulated by the membrane-specific distribution of SNARE (solubleN-ethylmaleimide-sensitive factor attachment protein receptor) proteins. However, the signals and machineries involved in SNARE protein targeting to the respective intracellular locations are not fully understood. We have identified a Sec22 ortholog inPlasmodium falciparum(PfSec22) that contains an atypical insertion of thePlasmodiumexport element within the N-terminal longin domain. This Sec22 protein partially associates with membrane structures in the parasitized erythrocytes when expressed under the control of the endogenous promoter element. Our studies indicate that the atypical longin domain contains signals that are required for both endoplasmic reticulum (ER)/Golgi apparatus recycling of PfSec22 and partial export beyond the ER/Golgi apparatus interface. ER exit of PfSec22 is regulated by motifs within the α3 segment of the longin domain, whereas the recycling and export signals require residues within the N-terminal hydrophobic segment. Our data suggest that the longin domain of PfSec22 exhibits major differences from the yeast and mammalian orthologs, perhaps indicative of a novel mechanism for Sec22 trafficking in malaria parasites.
The Laminin-Binding Protein Lbp from
Streptococcus pyogenes
Is a Zinc Receptor
Authors: Linke Christian , Caradoc-Davies Tom T. , Young Paul G. , Proft Thomas , Baker Edward N.
Published: July 2009

The common pathogen
Streptococcus pyogenes
colonizes the human skin and tonsils and can invade underlying tissues. This requires the adhesion of
S. pyogenes
to host surface receptors mediated through adhesins. The laminin-binding protein Lbp has been suggested as an adhesin, specific for the human extracellular matrix protein laminin. Sequence alignments, however, indicate a relationship between Lbp and a family of bacterial metal-binding receptors. To further analyze the role of Lbp in
S. pyogenes
and its potential role in pathogenicity, Lbp has been crystallized, and its structure has been solved at a resolution of 2.45 Å (
R
= 0.186;
R
free
= 0.251). Lbp has the typical metal-binding receptor fold, comprising two globular (β/α)
4
domains connected by a helical backbone. The two domains enclose the metal-binding site, which contains a zinc ion. The interaction of Lbp with laminin was further investigated and shown to be specific in vitro. Localization studies with antibodies specific for Lbp show that the protein is attached to the membrane. The data suggest that Lbp is primarily a zinc-binding protein, and we suggest that its interaction with laminin in vivo may be mediated via zinc bound to laminin.
Isoprenoids Are Essential for Fruiting Body Formation in
Myxococcus xanthus
Authors: Lorenzen Wolfram , Ring Michael W. , Schwär Gertrud , Bode Helge B.
Published: July 2009

It was recently shown that
Myxococcus xanthus
harbors an alternative and reversible biosynthetic pathway to isovaleryl coenzyme A (CoA) branching from 3-hydroxy-3-methylglutaryl-CoA. Analyses of various mutants in these pathways for fatty acid profiles and fruiting body formation revealed for the first time the importance of isoprenoids for myxobacterial development.
Escherichia coli
DksA Binds to Free RNA Polymerase with Higher Affinity than to RNA Polymerase in an Open Complex
Authors: Lennon Christopher W. , Gaal Tamas , Ross Wilma , Gourse Richard L.
Published: July 2009

The transcription factor DksA binds in the secondary channel of RNA polymerase (RNAP) and alters transcriptional output without interacting with DNA. Here we present a quantitative assay for measuring DksA binding affinity and illustrate its utility by determining the relative affinities of DksA for three different forms of RNAP. Whereas the apparent affinities of DksA for RNAP core and holoenzyme are the same, the apparent affinity of DksA for RNAP decreases almost 10-fold in an open complex. These results suggest that the conformation of RNAP present in an open complex is not optimal for DksA binding and that DNA directly or indirectly alters the interface between the two proteins.
Draft Genome Sequence of the Extremely Acidophilic BacteriumAcidithiobacillus caldusATCC 51756 Reveals Metabolic Versatility in the GenusAcidithiobacillus
Authors: Valdes Jorge , Quatrini Raquel , Hallberg Kevin , Dopson Mark , Valenzuela Pablo D. T. , Holmes David S.
Published: July 2009

Acidithiobacillus caldusis an extremely acidophilic, moderately thermophilic, chemolithoautotrophic gammaproteobacterium that derives energy from the oxidation of sulfur and reduced inorganic sulfur compounds. Here we present the draft genome sequence ofAcidithiobacillus caldusATCC 51756 (the type strain of the species), which has permitted the prediction of genes for survival in extremely acidic environments, including genes for sulfur oxidation and nutrient assimilation.
Androgen receptor gene polymorphisms lean mass and performance in young men
Authors: Guadalupe-Grau Amelia , Rodríguez-González F Germán , Dorado Cecilia , Olmedillas Hugo , Fuentes Teresa , Pérez-Gómez Jorge , Delgado-Guerra Safira , Vicente-Rodríguez Germán , Ara Ignacio , Guerra Borja , Arteaga-Ortiz Rafael , Calbet José A L , Díaz-Chico B Nicolás
Published: July 2009

The exon-1 of the androgen receptor (AR) gene contains two repeat length polymorphisms which modify either the amount ofARprotein inside the cell (GGNn, polyglycine) or its transcriptional activity (CAGn, polyglutamine). ShorterCAGand/orGGNrepeats provide stronger androgen signalling and vice versa. To test the hypothesis thatCAGandGGNrepeatARpolymorphisms affect muscle mass and various variables of muscular strength phenotype traits, the length ofCAGandGGNrepeats was determined by PCR and fragment analysis and confirmed by DNA sequencing of selected samples in 282 men (28.6±7.6 years). Individuals were grouped asCAG short(CAGS) if harbouring repeat lengths of ≤21 andCAG long(CAGL) ifCAG>21. GGNwas considered short (GGNS) or long (GGNL) ifGGN≤23 or >23, respectively. No significant differences in lean body mass or fitness were observed between theCAGSandCAGLgroups, or betweenGGNSandGGNLgroups, but a trend for a correlation was found for theGGNrepeat and lean mass of the extremities (r=−0.11, p=0.06). In summary, the lengths ofCAGandGGNrepeat of theARgene do not appear to influence lean mass or fitness in young men.
Educational inequalities in smoking cessation trends in Italy, 1982–2002
Authors: Federico B , Costa G , Ricciardi W , Kunst A E
Published: July 2009

Background/aim:

Smoking prevalence rates are declining in most industrialised countries, partly because of growing cessation rates. However, little is known on recent time-trends in smoking cessation by socioeconomic position. This study aims to estimate educational inequalities in smoking cessation trends in Italy between 1982 and 2002.

Methods:

Data were derived from two national health interview surveys carried out in Italy in 1999–2000 (n = 34 789) and in 2004–2005 (n = 33 135). On the basis of respondents’ age at starting and age at quitting smoking, we computed age-standardised smoking cessation rates at ages 20–44 years for subjects who were current smokers between 1982 and 2002.

Results:

Smoking quit rates were approximately constant at a figure of about 2 per 100 person-years until the period 2000–2002, when they rapidly increased up to 3–4 per 100 person-years. Higher educated smokers constantly showed higher cessation rates than lower educated subjects (rate ratio 1.33; 95% CI 1.25 to 1.41 for men and 1.41; 95% CI 1.30 to 1.53 for women). The relative size of educational difference in smoking cessation did not significantly vary by period. However, in absolute terms, the increase in cessation rates in 2000–2002 was larger among higher educated smokers.

Conclusion:

Educational inequalities in smoking cessation persisted in both relative and absolute terms. The increase in smoking cessation rates in 2000–2002 suggests that tobacco control policies may have reached more disadvantaged smokers, although smokers of higher socioeconomic groups seem to have benefited the most.
Purification of cardiac myocytes from human heart biopsies for gene expression analysis
Authors: Kosloski L. M. , Bales I. K. , Allen K. B. , Walker B. L. , Borkon A. M. , Stuart R. S. , Pak A. F. , Wacker M. J.
Published: July 2009

The collection of gene expression data from human heart biopsies is important for understanding the cellular mechanisms of arrhythmias and diseases such as cardiac hypertrophy and heart failure. Many clinical and basic research laboratories conduct gene expression analysis using RNA from whole cardiac biopsies. This allows for the analysis of global changes in gene expression in areas of the heart, while eliminating the need for more complex and technically difficult single-cell isolation procedures (such as flow cytometry, laser capture microdissection, etc.) that require expensive equipment and specialized training. The abundance of fibroblasts and other cell types in whole biopsies, however, can complicate gene expression analysis and the interpretation of results. Therefore, we have designed a technique to quickly and easily purify cardiac myocytes from whole cardiac biopsies for RNA extraction. Human heart tissue samples were collected, and our purification method was compared with the standard nonpurification method. Cell imaging using acridine orange staining of the purified sample demonstrated that >98% of total RNA was contained within identifiable cardiac myocytes. Real-time RT-PCR was performed comparing nonpurified and purified samples for the expression of troponin T (myocyte marker), vimentin (fibroblast marker), and α-smooth muscle actin (smooth muscle marker). Troponin T expression was significantly increased, and vimentin and α-smooth muscle actin were significantly decreased in the purified sample ( n = 8; P < 0.05). Extracted RNA was analyzed during each step of the purification, and no significant degradation occurred. These results demonstrate that this isolation method yields a more purified cardiac myocyte RNA sample suitable for downstream applications, such as real-time RT-PCR, and allows for more accurate gene expression changes in cardiac myocytes from heart biopsies.
Dominant-negative p38α mitogen-activated protein kinase prevents cardiac apoptosis and remodeling after streptozotocin-induced diabetes mellitus
Authors: Thandavarayan Rajarajan A. , Watanabe Kenichi , Ma Meilei , Gurusamy Narasimman , Veeraveedu Punniyakoti T. , Konishi Tetsuya , Zhang Shaosong , Muslin Anthony J. , Kodama Makoto , Aizawa Yoshifusa
Published: July 2009

The p38 mitogen-activated protein kinase (MAPK) is activated during heart diseases that might be associated with myocardial damage and cardiac remodeling process. Diabetic cardiomyopathy is associated with increased oxidative stress and inflammation. The purpose of this study was to investigate the role of p38α MAPK after experimental diabetes by using transgenic (TG) mice with cardiac-specific expression of a dominant-negative mutant form of p38α MAPK. The elevation of blood glucose was comparable between the nontransgenic (NTG) and TG mice. The expression of phospho-p38 MAPK and phospho-MAPK-activated protein kinase 2 levels were significantly suppressed in TG mice heart than in NTG mice after diabetes induction. Left ventricular (LV) dimension in systole was smaller, and the percent fractional shortening was higher in diabetic TG mice compared with diabetic NTG mice. In addition, diabetic TG mice had reduced cardiac myocyte diameter, content of cardiac fibrosis, LV tissue expressions of atrial natriuretic peptide, transforming growth factor β1, and collagen III compared with diabetic NTG mice. Moreover, LV expression of NADPH oxidase subunits, p22phox, p67phox, gp91phox, and Nox4, reactive oxygen species and lipid peroxidation levels were significantly increased in diabetic NTG mice, but not in diabetic TG mice. Furthermore, myocardial apoptosis, the number of caspase-3-positive cells, and the downregulation of antiapoptotic protein Bcl-XLwere less in diabetic TG mice compared with diabetic NTG mice. In conclusion, our data establish that p38α MAPK activity is required for cardiac remodeling after diabetes induction and suggest that p38α MAPK may promote cardiomyocyte apoptosis by downregulation of Bcl-XL.
Inhaled carbon monoxide reduces leukocytosis in a murine model of sickle cell disease
Authors: Beckman Joan D. , Belcher John D. , Vineyard Julie V. , Chen Chunsheng , Nguyen Julia , Nwaneri M. Osita , O'Sullivan M. Gerard , Gulbahce Evin , Hebbel Robert P. , Vercellotti Gregory M.
Published: July 2009

Carbon monoxide (CO) has anti-inflammatory properties. We previously reported that acute treatments with inhaled CO inhibit vascular inflammation and hypoxia-induced vasoocclusion in sickle cell disease mouse models. Therefore, we hypothesized that chronic CO inhalation would decrease vascular inflammation and organ pathology in a sickle cell disease mouse model. The treatment of sickle cell disease mice with 25 or 250 parts/million inhaled CO for 1 h/day, 3 days/wk for 8–10 wk significantly decreased the total mean white blood cell, neutrophil, and lymphocyte counts in peripheral blood. Eight weeks of 250 parts/million CO treatments reduced staining for myeloid and lymphoid markers in the bone marrow of sickle mice. Bone marrow from treated sickle mice exhibited a significant decrease in colony-forming unit granulocyte-macrophage during colony-forming cell assays. Anti-inflammatory signaling pathways phospho-Akt and phospho-p38 MAPK were markedly increased in CO-treated sickle livers. Importantly, CO-treated sickle mice had a significant reduction in liver parenchymal necrosis, reflecting the anti-inflammatory benefits of CO. We conclude that inhaled CO may be a beneficial anti-inflammatory therapy for sickle cell disease.
Low-dose ouabain constricts small arteries from ouabain-hypertensive rats: implications for sustained elevation of vascular resistance
Authors: Zhang Jin , Hamlyn John M. , Karashima Eiji , Raina Hema , Mauban Joseph R. H. , Izuka Michelle , Berra-Romani Roberto , Zulian Alessandra , Wier W. Gil , Blaustein Mordecai P.
Published: July 2009

Prolonged ouabain administration to normal rats causes sustained blood pressure (BP) elevation. This ouabain-induced hypertension (OH) has been attributed, in part, to the narrowing of third-order resistance arteries (∼320 μm internal diameter) as a result of collagen deposition in the artery media (see Ref. 6 ). Here we describe the structural and functional properties of fourth-order mesenteric small arteries from control and OH rats, including the effect of low-dose ouabain on myogenic tone in these arteries. Systolic BP in OH rats was 138 ± 3 versus 124 ± 4 mmHg in controls ( P < 0.01). Pressurized (70 mmHg) control and OH arteries, with only a single layer of myocytes, both had ∼165-μm internal diameters and ∼20-μm wall thicknesses. Even after fixation, despite vasoconstriction, the diameters and wall thicknesses did not differ between control and OH fourth-order arteries, whereas in third-order arteries, both parameters were significantly smaller in OH than in controls. Myogenic reactivity was significantly augmented in OH fourth-order arteries. Nevertheless, phenylephrine- (1 μM) and high K+-induced vasoconstrictions and acetylcholine-induced vasodilation were comparable in control and OH arteries. Vasoconstrictions induced by 5 μM phenylephrine and by 10 mM caffeine in Ca2+-free media indicated that releasable sarcoplasmic reticulum Ca2+ stores were normal in OH arteries. Importantly, 100 nM ouabain constricted both control and OH arteries by ∼26 μm, indicating that this response was not downregulated in OH rats. This maximal ouabain-induced constriction corresponds to a ∼90% increase in resistance to flow in these small arteries; thus ouabain at EC50 of ∼0.66 nM should raise resistance by ∼35%. We conclude that dynamic constriction in response to circulating nanomolar ouabain in small arteries likely makes a major contribution to the increased vascular tone and BP in OH rats.
Myocardial reperfusion injury management: erythropoietin compared with postconditioning
Authors: Tamareille Sophie , Ghaboura Nehmat , Treguer Frederic , Khachman Dalia , Croué Anne , Henrion Daniel , Furber Alain , Prunier Fabrice
Published: July 2009

Ischemic postconditioning (IPost) and erythropoietin (EPO) have been shown to attenuate myocardial reperfusion injury using similar signaling pathways. The aim of this study was to examine whether EPO is as effective as IPost in decreasing postischemic myocardial injury in both Langendorff-isolated-heart and in vivo ischemia-reperfusion rat models. Rat hearts were subjected to 25 min ischemia, followed by 30 min or 2 h of reperfusion in the isolated-heart study. Rats underwent 45 min ischemia, followed by 24 h of reperfusion in the in vivo study. In both studies, the control group ( n = 12; ischemia-reperfusion only) was compared with IPost ( n = 16; 3 cycles of 10 s reperfusion/10 s ischemia) and EPO ( n = 12; 1,000 IU/kg) at the onset of reperfusion. The following resulted. First, in the isolated hearts, IPost or EPO significantly improved postischemic recovery of left ventricular developed pressure. EPO induced better left ventricular developed pressure than IPost at 30 min of reperfusion (73.18 ± 10.23 vs. 48.11 ± 7.92 mmHg, P < 0.05). After 2 h of reperfusion, the infarct size was significantly lower in EPO-treated hearts compared with IPost and control hearts (14.36 ± 0.60%, 19.11 ± 0.84%, and 36.21 ± 4.20% of the left ventricle, respectively; P < 0.05). GSK-3β phosphorylation, at 30 min of reperfusion, was significantly higher with EPO compared with IPost hearts. Phosphatidylinositol 3-kinase and ERK1/2 inhibitors abolished both EPO- and IPost-mediated cardioprotection. Second, in vivo, IPost and EPO induced an infarct size reduction compared with control (40.5 ± 3.6% and 28.9 ± 3.1%, respectively, vs. 53.7 ± 4.3% of the area at risk; P < 0.05). Again, EPO decreased significantly more infarct size and transmurality than IPost ( P < 0.05). In conclusion, with the use of our protocols, EPO showed better protective effects than IPost against reperfusion injury through higher phosphorylation of GSK-3β.
Protein disulfide isomerase increases in myocardial endothelial cells in mice exposed to chronic hypoxia: a stimulatory role in angiogenesis
Authors: Tian Fei , Zhou Xianghua , Wikström Johannes , Karlsson Helen , Sjöland Helén , Gan Li-Ming , Borén Jan , Akyürek Levent M.
Published: July 2009

Previous studies have shown that exposure to chronic hypoxia protects against myocardial infarction, but little is known about the cellular and molecular mechanisms involved. Here we observed that chronic hypoxia for 3 wk resulted in improved survival of mice (from 64% to 83%), reduced infarction size (from 45 ± 4% to 32 ± 4%, P < 0.05), increased cardiac ejection fraction (from 19 ± 4% to 35 ± 5%, P < 0.05), coronary flow velocity under adenosine-induced hyperemia (from 58 ± 2 to 75 ± 5 cm/s, P < 0.05), myocardial capillary density (from 3,772 ± 162 to 4,760 ± 197 capillaries/mm2, P < 0.01), and arteriolar density (from 8.04 ± 0.76 to 10.34 ± 0.69 arterioles/mm2, P < 0.05) 3 wk after myocardial infarction. With two-dimensional gel electrophoresis, we identified that protein disulfide isomerase (PDI) was highly upregulated in hypoxic myocardial capillary endothelial cells. The loss of PDI function in endothelial cells by small interfering RNA significantly increased the number of apoptotic cells (by 3.4-fold at hypoxia, P < 0.01) and reduced migration (by 52% at hypoxia, P < 0.001) and adhesion to collagen I (by 42% at hypoxia, P < 0.01). In addition, the specific inhibition of PDI by PDI small interfering RNA (by 46%, P < 0.01) and bacitracin (by 72%, P < 0.001) reduced the formation of tubular structures by endothelial cells. Our data indicate that chronic hypoxic exposure improves coronary blood flow and protects the myocardium against infarction. These beneficial effects may be partly explained by the increased endothelial expression of PDI, which protects cells against apoptosis and increases cellular migration, adhesion, and tubular formation. The increased PDI expression in endothelial cells may be a novel mechanism to protect the myocardium against myocardial ischemic diseases.
Neonatal oxygen adversely affects lung function in adult mice without altering surfactant composition or activity
Authors: Yee Min , Chess Patricia R. , McGrath-Morrow Sharon A. , Wang Zhengdong , Gelein Robert , Zhou Rui , Dean David A. , Notter Robert H. , O'Reilly Michael A.
Published: July 2009

Despite its potentially adverse effects on lung development and function, supplemental oxygen is often used to treat premature infants in respiratory distress. To understand how neonatal hyperoxia can permanently disrupt lung development, we previously reported increased lung compliance, greater alveolar simplification, and disrupted epithelial development in adult mice exposed to 100% inspired oxygen fraction between postnatal days 1 and 4. Here, we investigate whether oxygen-induced changes in lung function are attributable to defects in surfactant composition and activity, structural changes in alveolar development, or both. Newborn mice were exposed to room air or 40%, 60%, 80%, or 100% oxygen between postnatal days 1 and 4 and allowed to recover in room air until 8 wk of age. Lung compliance and alveolar size increased, and airway resistance, airway elastance, tissue elastance, and tissue damping decreased, in mice exposed to 60–80% oxygen; changes were even greater in mice exposed to 100% oxygen. These alterations in lung function were not associated with changes in total protein content or surfactant phospholipid composition in bronchoalveolar lavage. Moreover, surface activity and total and hydrophobic protein content were unchanged in large surfactant aggregates centrifuged from bronchoalveolar lavage compared with control. Instead, the number of type II cells progressively declined in 60–100% oxygen, whereas levels of T1α, a protein expressed by type I cells, were comparably increased in mice exposed to 40–100% oxygen. Thickened bundles of elastin fibers were also detected in alveolar walls of mice exposed to ≥60% oxygen. These findings support the hypothesis that changes in lung development, rather than surfactant activity, are the primary causes of oxygen-altered lung function in children who were exposed to oxygen as neonates. Furthermore, the disruptive effects of oxygen on epithelial development and lung mechanics are not equivalently dose dependent.
Measurement of extravascular lung water using the single indicator method in patients: research and potential clinical value
Authors: Brown Lisa M. , Liu Kathleen D. , Matthay Michael A.
Published: July 2009

Extravascular lung water includes all of the fluid within the lung but outside of the vasculature. Lung water increases as a result of increased hydrostatic vascular pressure or from an increase in lung endothelial and epithelial permeability or both. Experimentally, extravascular lung water has been measured gravimetrically. Clinically, the chest radiograph is used to determine whether extravascular lung water is present but is an insensitive instrument for determining the quantity of lung water. Bedside measurement of extravascular lung water in patients is now possible using a single indicator thermodilution method. This review critically evaluates the experimental and clinical evidence supporting the potential value of measuring extravascular lung water in patients using the single indicator method.
The soluble guanylate cyclase activator HMR1766 reverses hypoxia-induced experimental pulmonary hypertension in mice
Authors: Weissmann Norbert , Hackemack Sascha , Dahal Bhola Kumar , Pullamsetti Soni Savai , Savai Rajkumar , Mittal Manish , Fuchs Beate , Medebach Thomas , Dumitrascu Rio , Eickels Martin van , Ghofrani Hossein Ardeschir , Seeger Werner , Grimminger Friedrich , Schermuly Ralph Theo
Published: July 2009

Severe pulmonary hypertension (PH) is a disabling disease with high mortality, characterized by pulmonary vascular remodeling and right heart hypertrophy. In mice with PH induced by chronic hypoxia, we examined the acute and chronic effects of the soluble guanylate cyclase (sGC) activator HMR1766 on hemodynamics and pulmonary vascular remodeling. In isolated perfused mouse lungs from control animals, HMR1766 dose-dependently inhibited the pressor response of acute hypoxia. This dose-response curve was shifted leftward when the effects of HMR1766 were investigated in isolated lungs from chronic hypoxic animals for 21 days at 10% oxygen. Mice exposed for 21 or 35 days to chronic hypoxia developed PH, right heart hypertrophy, and pulmonary vascular remodeling. Treatment with HMR1766 (10 mg·kg−1·day−1), after full establishment of PH from day 21 to day 35, significantly reduced PH, as measured continuously by telemetry. In addition, right ventricular (RV) hypertrophy and structural remodeling of the lung vasculature were reduced. Pharmacological activation of oxidized sGC partially reverses hemodynamic and structural changes in chronic hypoxia-induced experimental PH.
Effects of Permeability on Perceived Enclosure and Spaciousness
Authors: Stamps Arthur E.
Published: July 2009

This article suggests that the ranges through which people can see through or move through environments are extremely important.The label corresponding to this theory is permeability theory. Eight hypotheses are generated from permeability theory using two responses (perceived enclosure and perceived spaciousness) and four properties of the physical environment (permeability of boundary, amount of light, horizontal area within a boundary, and boundary depth). Empirical data from 4 experiments, 54 environments, and 130 participants indicate that permeability theory correctly predicted 6 a priori hypotheses and also correctly predicted that the remaining 2 hypotheses would have effect sizes too small to detect. The main determinants of judged enclosure or spaciousness are visual permeability of the boundary, amount of light, and horizontal area. Numerical guidance is provided to assist future research.
Developing Strategies for Waste Reduction by Means of Tailored Interventions in Santiago de Cuba
Authors: Tobias Robert , Brügger Adrian , Mosler Hans-Joachim
Published: July 2009

This article introduces an approach to tailoring behavior-change campaigns to target populations using the example of solid waste reduction in Santiago de Cuba. Tailoring is performed in the following steps: (1) Psychological constructs are selected to detect problems in performing the target behavior, and data are gathered on these constructs. (2) Cluster analyses are performed on these data to identify different psychological types and their distribution in the population. (3) Intervention techniques are assigned according to the spatial and quantitative distribution and the characteristics of these types. Results of the cluster analyses are presented for three different behaviors that can reduce the amount of deposited solid waste (recycling, composting, reuse) on the basis of the four psychological constructs of instrumental and affective attitude, difficulty, and social pressure. The tailoring of interventions could be used to design environmental campaigns more efficiently.
Viewpoint Animation With a Dynamic Tether for Supporting Navigation in a Virtual Environment
Authors: Wang Wenbi , Milgram Paul
Published: July 2009

Objective: This study examined the concept of dynamic viewpoint tethering for enhancing performance in 3-D avatar control tasks. Background: Dynamic viewpoint tethering refers to a viewpoint animation technique that couples a display viewpoint to a controlled avatar through a virtual tether. A dynamic tether, modeled as a mass spring damper system, can potentially generate desirable viewpoint behavior because of its ability to produce frequency-separated viewpoint responses. This study investigated the impact of a tether’s rigidity and damping properties on users’ navigational performance. Methods: Twelve participants took part in a simulated 3-D aerial navigational task. Performance was evaluated with respect to local guidance and global awareness. Results: Root mean square error scores revealed a decrease in local guidance performance when (a) the tether was either severely underdamped or overdamped and (b) the tether’s rigidity approached either zero or infinity. In addition, (c) global performance was better for higher-frequency forcing functions. Conclusion: Critical damping and medium rigidity can be optimized during design for enhancing users’ navigational efficiency. Application: Guidelines generated from this study support future viewpoint design in interactive virtual reality applications.
Does ‘No Pesticide’ Reduce Suicides?
Authors: Vijayakumar Lakshmi , Satheesh-Babu R.
Published: July 2009

Introduction: Ingestion of pesticides is the most common method of suicide, particularly in China, Sri Lanka and India. Reported pesticide suicides in India numbered 22,000 in the year 2006.z

Method: Four villages in the state of Andhra Pradesh in India that had stopped using chemical pesticides in favour of non-pesticide management (NPM) were visited to assess any change in suicide incidence before and after discontinuation of chemical pesticides. Four similar villages in the same region that continued to use chemical pesticides were used as controls for comparison.

Results: In the pesticide-free villages there were 14 suicides before introduction of NPM and only three suicides thereafter. The percentage of suicides not reported to authorities was 47%.

Conclusion: Restriction of pesticide availability and accessibility by NPM has the potential to reduce pesticide suicides, in addition to psychosocial and health interventions.