bluuebunny/crossref_metadata_2025 huggingface dataset:
A kinematic and dynamic analysis on orthotic gait of paraplegics
Authors: Kagawa Takahiro , Fukuda Hiroshi , Uno Yoji
Published: July 2007

In this study, we attempt to quantify the relationship between significant arm‐clutch loading, leg restriction, and motor paralysis, and analyze lumbar joint trajectories in the orthotic gait of paraplegic subjects and in the ordinary and orthotic gaits of a normal subject, by using an inverted pendulum model. With leg restriction, the trajectories are located in front of an equilibrium point of the inverted pendulum, and the loading is higher due to the influence of the gravity moment. Comparing the trajectories of paraplegic and normal gait with orthosis in the horizontal plane, the trajectory in the paraplegic subjects was rectilinear, while that in the normal subject was curved in the direction toward the equilibrium point. The loading is lower in the curved trajectory than in the straight trajectory because of the trade‐off between gravity and inertia. These results suggest that the increase in the distance between the trunk movement and the equilibrium point of the inverted pendulum results in significant loading due to leg restriction and motor paralysis in the orthotic gait of paraplegics. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(3): 10– 21, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20533
Experimental study on the Unified Power Flow Controller
Authors: Matsuki Junya , Hayashi Yasuhiro , Kitajima Shunsuke , Takahashi Masahiro , Murata Kenji
Published: July 2007

This paper presents the results of experimental study on the performance of a Unified Power Flow Controller (UPFC), one of the FACTS (Flexible AC Transmission Systems) controllers. A laboratory‐scale UPFC was manufactured and installed on a laboratory electric power system to investigate its multifunctional capabilities as a power flow controller. The UPFC consists of two 4.5‐kVA, 200‐V back‐to‐back voltage‐sourced converters, labeled “Converter 1” and “Converter 2,” operated from a common DC link provided by a DC storage capacitor of 380 V. It can provide independent control of both the real and reactive power flow in the line. Tests were performed to examine the capabilities of the UPFC, under one‐machine connected to an infinite‐bus system. Steady‐state responses under various kinds of operating conditions were measured and analyzed. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(2): 8– 15, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20538
Theoretical study of methods for improving the energy efficiency of NOx removal from diesel exhaust gases by silent discharge
Authors: Shoyama Taiji , Yoshioka Yoshio
Published: July 2007

To improve the NO removal performance in silent discharge process, we investigated the influence of physical parameters such as current density, channel radius, and pulse duration of one micro‐discharge under a constant reduced electric field strength. The influence of micro‐discharge occurrence locations was also discussed. In order to analyze the NO removal process, we assumed that the pulse micro‐discharges occur repeatedly at the same location in static gas and that the chemical reactions induced by micro‐discharge form many radicals, which react with pollutants and by‐products. The conclusions we obtained are that lower current density, smaller discharge radius, and shorter discharge duration improve NO removal efficiency. These results also mean that the lower discharge energy of one micro‐discharge and the larger number of parallel micro‐discharges increase the NO removal performance. Therefore, making the area of one micro‐discharge small is a desirable way to improve the NO removal performance. Thus, we think that the glow‐like discharge might be more effective than the streamer‐like discharge mode. Next, using the two‐dimensional model, which considered the influence of gas flow, we found that the repeated micro‐discharges at different positions are very effective to increase the De‐NOx performance. The reason is that the reaction of NO2+O→NO+O2 and ozone dissociation reactions are suppressed by the movement of the location of micro discharges. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(3): 1–9, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20556
Plasma generation at atmospheric pressure using a high‐power microwave beam and its application to rocket propulsion
Authors: Oda Yasuhisa , Komurasaka Kimiya , Takahashi Koji , Kasugai Atsushi , Imai Tsuyoshi , Sakamoto Keishi
Published: July 2007

Experiments on microwave plasma generation and its application to microwave beamed energy propulsion were conducted using a 1‐MW‐class, 170‐GHz gyrotron. The microwave beam was focused using a parabola reflector and plasma was initiated near the focal point in the ambient air. Plasma propagated upstream in the microwave beam channel while absorbing microwaves. Its propagation velocity was supersonic when the microwave power density was greater than 75 kW/cm2. The propulsive impulse was measured using a cone‐cylinder‐shaped thruster model. As a result, the maximum momentum coupling coefficient was obtained at a certain plasma propagation distance. In addition, a larger momentum coupling coefficient was obtained when plasma was propagated at a supersonic velocity. This is because supersonic plasma propagation forms a strong shock wave, resulting in an efficient pressure increase. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(2): 1– 7, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20573
Eddy current flaw testing probe with high performance in detecting flaws during in‐service inspection of tubing
Authors: Koyama Kiyoshi , Hoshikawa Hiroshi
Published: July 2007

Eddy current flaw testing that uses changes in the impedance of the test coil as an electromagnetic field interacts with the test material is a nondestructive testing method. It can be used to inspect test material at high speed without bringing the test coil into contact with the test material. Therefore, it is widely used for product inspection. In the inspection of heat exchanger tubing in power plants and chemical plants, eddy current flaw testing is performed by using an inner probe, because of the structural restrictions of such plants. However, high levels of wobble noise and support plate noise occur in the conventional method using a rotating pancake coil. The authors therefore propose new minimal‐noise eddy current inner probes. Two new types of probes have been developed: one for detecting axial flaws and the other for detecting circumference flaws. These probes can detect flaws with a low level of noise. The phase of the flaw signal by the new probes changes according to the flaw depth. As a result, the signal phase by the new probes can be used for evaluating the depth of surface flaws. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(2): 52–61, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20605
Why are Phosphole Oxides Unstable? The Phenomenon of Antiaromaticity as a Destabilizing Factor
Authors: Mucsi Zoltán , Keglevich György
Published: July 2007

It is shown that the great instability of phosphole oxides can be attributed to their antiaromatic characters. The aromatic–antiaromatic switch in the course of the oxidation of phospholes, which may be fine‐tuned by P substituents, increases the reactivity toward dimerisation, leading to the corresponding 7‐phosphanorbornene rings. The degree of antiaromaticity of these stable compounds is examined and quantified on a linear aromatic and antiaromatic scale. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Linear versus Angular Fischer Indole Annulation: Relative Configuration Determines Regioselectivity
Authors: Diedrich Claas Lüder , Frey Wolfgang , Christoffers Jens
Published: July 2007

Fischer indole synthesis with bicyclic ketones yields regioselectively linear annulated tetracyclic products when starting from ketones with a relative trans configuration. On the other hand, starting materials with a relative cis configuration give exclusively angular annulated indole derivatives. The starting materials were prepared in optically active form in three steps by a sequence of asymmetric Michael reaction, aldol condensation, and catalytic hydrogenation. The last step yields a mixture of cis and trans diastereoisomers which can be separated by column chromatography. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
On the Mechanism of the Puzzling “Endocyclic” Skeletal Rearrangement of 1,6‐Enynes
Authors: Cabello Noemí , Jiménez‐Núñez Eloísa , Buñuel Elena , Cárdenas Diego J. , Echavarren Antonio M.
Published: July 2007

Skeletal rearrangements of simple 1,6‐enynes have been studied in order to determine the factors that control the formation of five‐ or six‐membered rings. Simple 1,6‐enynes substituted only at C‐4 preferentially give six‐membered rings on skeletal rearrangement in the presence of gold(I) catalysts, whereas increasing electron‐withdrawing character of substituents at C‐4 leads to five‐membered rings. Reactions of these simple enynes in the presence of PtCl4 as catalyst give exclusively exo‐double skeletal rearrangements. Enynes substituted at the alkyne also react with AuI catalysts to give exclusively products of exo‐double rearrangement. The different mechanisms have been analyzed by DFT calculations. Although a pathway for the formation of six‐membered rings involving two steps in a ring‐expansion/ring‐contraction process was found, the activation energy of the first step is too high. Instead, this skeletal rearrangement appears to follow an exo‐single skeletal rearrangement in which the initial cyclopropyl gold carbene opens to form a six‐membered ring. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Highly Selective Hydroformylation of Vinylarenes to Branched Aldehydes by [Rh(cod)Cl]2 Entrapped in Ionic Liquid Modified Silica Sol‐Gel
Authors: Hamza Khalil , Blum Jochanan
Published: July 2007

A co‐entrapped mixture of [Rh(cod)Cl]2 and Na[Ph2P‐3‐(C6H4SO3)] within a silica sol‐gel matrix modified with ca. 5 % of 1‐butyl‐3‐[3‐(trimethoxysilyl)propyl]imidazolium chloride catalyzes, in n‐heptane, the hydroformylation of a variety of vinylarenes. At 50 °C and under 6.9 bar each of H2 and CO the reaction is high‐yielding and highly selective. Non‐hindered substrates give >95 % of branched aldehydes and only <5 % of the linear isomers. The ceramic catalyst isleach‐proof and recyclable. It does not lose its high catalytic activity and selectivity for at least four runs. The selectivity depends on the pressure of the gases, the temperature and the solvent. The electronic nature has no influence on the selectivity, but the latter is diminished by steric effects. Upon omission of the sol‐gel component, the catalyst deteriorates and practically loses its activity after the first half‐life of the reaction. In the absence of the ionic liquid, the catalyst undergoes substantial leaching.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis of meso‐Coumarin‐Conjugated Porphyrins and Investigation of Their Luminescence Properties
Authors: Lin Weiying , Long Lingliang , Feng Jianbo , Wang Bin , Guo Cancheng
Published: July 2007

A series of meso‐coumarin‐conjugated porphyrins 1a–e were designed and synthesized. Condensation of 4‐chloroacetoacetate ethyl ester with m‐cresol or resorcin afforded 4‐chloromethylcoumarins, which were then hydrolyzed to give coumarin alcohols, followed by oxidation to provide coumarin aldehydes. The reaction of coumarin aldehydes with pyrrole under Adler or Lindsey conditions afforded the meso‐coumarin‐conjugated porphyrins 1a–e. Their UV/Vis absorption spectra and photoluminescent spectra were recorded both in dilute THF solution and as solid films. Analysis of the luminescence spectra indicate that the energy transfer from the coumarin substituents to the porphyrin core for 1a–e is more efficient in solid film than in solution, and the energy transfer from the coumarin substituent to the porphyrin core for 1d and 1e is more efficient than that of 1a, 1b and 1c in solid film. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Synthesis and Reactivity of 23‐tert‐Butyl‐ and 23‐Phenyltetraarylazuliporphyrins: an Analysis of the Effect of Bulky Substituents on Oxidative Ring Contractions to Benzocarbaporphyrins
Authors: El‐Beck Jessica A. , Lash Timothy D.
Published: July 2007

6‐tert‐Butyl‐ and 6‐phenylazulene reacted with pyrrole and benzaldehyde in a molar ratio of 1:3:4 in the presence of BF3·Et2O in chloroform, followed by oxidation with DDQ, to give 23‐substituted tetraphenylazuliporphyrins in 15–20 % yield. Slightly higher yields of the related meso‐tetrakis(4‐chlorophenyl)azuliporphyrins were obtained using 4‐chlorobenzaldehyde. The presence of an electron‐donating tert‐butyl substituent increased the diatropic character of the azuliporphyrin system as determined by the proton NMR chemical shifts for the internal CH resonance, while intermediary results were noted for 23‐phenylazuliporphyrins. Addition of TFA afforded dications with increased aromatic ring currents, but electron‐donating substituents (tBu > Ph) again produced a larger upfield shift for the internal CH signal due to stabilization of the tropylium character that is required so that the system can attain carbaporphyrin‐type aromaticity. The substituted azuliporphyrins reacted with nickel(II) acetate or palladium(II) acetate to give the corresponding organometallic derivatives. In addition, oxidations with tBuOOH and KOH afforded benzocarbaporphyrin products in approximately 50 % yield. The presence of tert‐butyl or phenyl substituents did not block these oxidative ring contraction processes, and the rate of reaction was slightly increased compared to 23‐unsubstituted azuliporphyrins. The major products were 22‐tert‐butyl or phenyl‐substituted benzocarbaporphyrins and minor products with an additional formyl substituent were also isolated. These products are consistent with an initial nucleophilic addition occurring at the position adjacent to the R group on the azulene ring. Detailed mechanisms are proposed to explain these observations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
The power of two‐locus affected sib‐pair linkage analysis to detect interacting disease loci
Authors: Hallgrímsdóttir Ingileif B. , Speed Terence P.
Published: July 2007

It has been shown that two‐locus linkage analysis can, for some two‐locus disease models, be used to detect effects at disease loci that do not reach significance in a genome scan. However, few examples exist where two‐locus linkage has been successfully used to map genes. We study the possible gain in power of affected sib‐pair nonparametric two‐locus linkage analysis for two‐locus models which fulfil the two‐locus triangle constraints. Using a new parameterization of the two‐locus joint identity‐by‐descent sharing probabilities we can, for fixed marginal sharing at both of two unlinked disease loci, derive a two‐locus distribution such that the power of a two‐locus analysis is maximized. In a simulation study we look at two test statistics, the two‐locus maximum likelihood score and the correlation between nonparametric linkage scores, and study power as a function of marginal sharing. We show that in a best‐case scenario two‐locus linkage can have considerable power to detect pairs of interacting loci if there is a moderate increase in allele sharing at one of the two loci, even if there is a very small increase in allele sharing at the other locus. But we also show that the power to detect interacting loci in a two‐locus analysis decreases as the marginal sharing at the two loci decreases and for any distribution with a small increase in allele sharing at both loci the power of a two‐locus analysis is always low. Genet. Epidemiol. 2007. © 2007 Wiley‐Liss, Inc.
Multiple cascade effects of oxidative stress on astroglia
Authors: Bond Cherie E. , Greenfield Susan A.
Published: July 2007

Many neurodegenerative diseases share common underlying features, most prominent of which are dysregulation of calcium homeostasis and reactive astrogliosis, ultimately triggered by oxidative stress. Interestingly, an additional feature of the early response to stress conditions is the upregulation and release of acetylcholinesterase (AChE). This study therefore investigates the link between oxidative stress, calcium influx, gene expression, protein synthesis, and AChE release. We report that, in astroglia and in an immortalized cell line, GH4‐hα7, acute oxidative stress causes influx of extracellular calcium through L‐type voltage‐gated calcium channels (L‐VGCC), followed by increased release of AChE into the extracellular medium. Moreover, rapid and sustained changes in mRNA expression of AChE, L‐VGCC, and melastatin‐like transient receptor potential 2 (TRPM2) accompany profound suppression of global protein synthesis. Application of L‐VGCC blockers selectively reduces stress‐induced calcium influx and AChE release, mitigates changes in gene expression, and facilitates recovery from protein synthesis suppression. Although glia exhibit greater sensitivity in their responses, the results are comparable in astroglia and GH4‐hα7 cells, and suggest a generalized and integrated cellular response to stress conditions that characterizes changes observed in neurodegeneration. © 2007 Wiley‐Liss, Inc.
Proteomic profiling of human liver biopsies: Hepatitis C virus–induced fibrosis and mitochondrial dysfunction
Authors: Diamond Deborah L. , Jacobs Jon M. , Paeper Bryan , Proll Sean C. , Gritsenko Marina A. , Carithers Robert L. , Larson Anne M. , Yeh Matthew M. , Camp David G. , Smith Richard D. , Katze Michael G.
Published: July 2007

Liver biopsies from hepatitis C virus (HCV)-infected patients offer the unique opportunity to study human liver biology and disease

in vivo

. However, the low protein yields associated with these small samples present a significant challenge for proteomic analysis. In this study we describe the application of an ultrasensitive proteomics platform for performing robust quantitative proteomic studies on microgram amounts of HCV-infected human liver tissue from 15 patients at different stages of fibrosis. A high-quality liver protein database containing 5,920 unique protein identifications supported high throughput quantitative studies using 16O/18O stable isotope labeling in combination with the accurate mass and time (AMT) tag approach. A total of 1,641 liver biopsy proteins were quantified, and analysis of variance (ANOVA) identified 210 proteins exhibiting statistically significant differences associated with fibrosis stage. Hierarchical clustering showed that biopsies representative of later fibrosis stages (for example, Batts-Ludwig stages 3–4) exhibited a distinct protein expression profile, indicating an apparent down-regulation of many proteins when compared with samples from earlier fibrosis stages (for example, Batts-Ludwig stages 0–2). Functional analysis of these signature proteins suggests that impairment of key mitochondrial processes including fatty acid oxidation and oxidative phosphorylation, and response to oxidative stress and reactive oxygen species occurs during advanced stage 3 to 4 fibrosis.

Conclusion:

The results reported here represent a significant advancement in clinical proteomics providing to our knowledge, the first demonstration of global proteomic alterations accompanying liver disease progression in patients chronically infected with HCV. Our findings contribute to a generally emerging theme associating oxidative stress and hepatic mitochondrial dysfunction with HCV pathogenesis. (Hepatology 2007.)
Tumor necrosis factor alpha inhibits the suppressive effect of regulatory T cells on the hepatitis B virus–specific immune response
Authors: Stoop Jeroen N. , Woltman Andrea M. , Biesta Paula J. , Kusters Johannes G. , Kuipers Ernst J. , Janssen Harry L.A. , van der Molen Renate G.
Published: July 2007

Chronicity of hepatitis B virus (HBV) infection is characterized by a weak immune response to the virus. CD4+CD25+ regulatory T cells (Treg) are present in increased numbers in the peripheral blood of chronic HBV patients, and these Treg are capable of suppressing the HBV-specific immune response. The aim of this study was to abrogate Treg-mediated suppression of the HBV-specific immune response. Therefore, Treg and a Treg-depleted cell fraction were isolated from peripheral blood of chronic HBV patients. Subsequently, the suppressive effect of Treg on the response to HBV core antigen (HBcAg) and tetanus toxin was compared, and the effect of exogenous tumor necrosis factor alpha (TNF-α), interleukin-1-beta (IL-1β), or neutralizing antibodies against interleukin-10 (IL-10) or transforming growth factor beta (TGF-β) on Treg-mediated suppression was determined. The results show that Treg of chronic HBV patients had a more potent suppressive effect on the response to HBcAg compared with the response to tetanus toxin. Neutralization of IL-10 and TGF-β or exogenous IL-1β had no effect on Treg-mediated suppression of the anti-HBcAg response, whereas exogenous TNF-α partially abrogated Treg-mediated suppression. Preincubation of Treg with TNF-α demonstrated that TNF-α had a direct effect on the Treg. No difference was observed in the type II TNF receptor expression by Treg from chronic HBV patients and healthy controls.

Conclusion:

Treg-mediated suppression of the anti-HBV response can be reduced by exogenous TNF-α. Because chronic HBV patients are known to produce less TNF-α, these data implicate an important role for TNF-α in the impaired antiviral response in chronic HBV. (Hepatology 2007.)
A lipidomic analysis of nonalcoholic fatty liver disease
Authors: Puri Puneet , Baillie Rebecca A. , Wiest Michelle M. , Mirshahi Faridoddin , Choudhury Jayanta , Cheung Onpan , Sargeant Carol , Contos Melissa J. , Sanyal Arun J.
Published: July 2007

The spectrum of nonalcoholic fatty liver disease (NAFLD) includes a nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). The specific types and amounts of lipids that accumulate in NAFLD are not fully defined. The free fatty acid (FFA), diacylglycerol (DAG), triacylglycerol (TAG), free cholesterol (FC), cholesterol ester, and phospholipid contents in normal livers were quantified and compared to those of NAFL and NASH, and the distribution of fatty acids within these classes was compared across these groups. Hepatic lipids were quantified by capillary gas chromatography. The mean (nmol/g of tissue) DAG (normal/NAFL/NASH: 1922 versus 4947 versus 3304) and TAG (13,609 versus 128,585 versus 104,036) increased significantly in NAFLD, but FFA remained unaltered (5533 versus 5929 versus 6115). There was a stepwise increase in the mean TAG/DAG ratio from normal livers to NAFL to NASH (7 versus 26 versus 31,

P

< 0.001). There was also a similar stepwise increment in hepatic FC (7539 versus 10,383 versus 12,863,

P

< 0.05 for NASH). The total phosphatidylcholine (PC) decreased in both NAFL and NASH. The FC/PC ratio increased progressively (0.34 versus 0.69 versus 0.71,

P

< 0.008 for both). Although the levels for linoleic acid (18:2n-6) and α-linolenic acid (18:3n-3) remained unaltered, there was a decrease in arachidonic acid (20:4n-6) in FFA, TAG, and PC (

P

< 0.05 for all) in NASH. Eicosapentanoic acid (20:5n-3) and docosahexanoic acid (22:6n-3) were decreased in TAG in NASH. The n-6:n-3 FFA ratio increased in NASH (

P

< 0.05).

Conclusions:

NAFLD is associated with numerous changes in the lipid composition of the liver. The potential implications are discussed. (HEPATOLOGY 2007.)
Role of the coagulation system in acetaminophen-induced hepatotoxicity in mice
Authors: Ganey Patricia E. , Luyendyk James P. , Newport Sandra W. , Eagle Theresa M. , Maddox Jane F. , Mackman Nigel , Roth Robert A.
Published: July 2007

Acetaminophen (

N-acetyl
-
p

-aminophenol [APAP]) is one of the leading causes of acute liver failure, and APAP hepatotoxicity is associated with coagulopathy in humans. We tested the hypothesis that activation of the coagulation system and downstream protease-activated receptor (PAR)-1 signaling contribute to APAP-induced liver injury. Fasted C57BL/J6 mice were treated with either saline or APAP (400 mg/kg intraperitoneally) and were euthanized 0.5-24 hours later. Hepatotoxicity and coagulation system activation occurred by 2 hours after administration of APAP. Treatment with APAP also caused a rapid and transient increase in liver procoagulant activity. In addition, significant deposition of fibrin was observed in the liver by 2 hours, and the concentration of plasminogen activator inhibitor-1 in plasma increased between 2 and 6 hours. Pretreatment with heparin attenuated the APAP-induced activation of the coagulation system and hepatocellular injury and diminished hepatic fibrin deposition at 6 hours. Loss of hepatocellular glutathione was similar in APAP-treated mice pretreated with saline or heparin, suggesting that heparin did not diminish bioactivation of APAP. In mice deficient in tissue factor, the principal cellular activator of coagulation, APAP-induced liver injury, activation of coagulation, and hepatic fibrin deposition were reduced at 6 hours. Formation of the tissue factor–factor VIIa complex leads to the generation of thrombin that can activate cells through cleavage of PAR-1. Mice lacking PAR-1 developed less injury and hepatic fibrin deposits at 6 hours in response to APAP than control mice.

Conclusion:

Activation of the coagulation system and PAR-1 signaling contribute significantly to APAP-induced liver injury. (HEPATOLOGY 2007.)
Hepatitis B virus DNA prediction rules for hepatitis B e antigen–negative chronic hepatitis B
Authors: Feld Jordan J. , Ayers Melissa , El-Ashry Dahlia , Mazzulli Tony , Tellier Raymond , Heathcote Jenny E.
Published: July 2007

After hepatitis B e antigen (HBeAg) seroconversion, hepatitis B may become inactive or progress to HBeAg-negative hepatitis with persistent or intermittent alanine aminotransferase (ALT) elevation. The aim of this study was to prospectively identify factors predictive of the clinical course in HBeAg-negative chronic hepatitis B (CHB). Patients were stratified by ALT and HBeAg status and followed every 3 months for up to 5 years. Kaplan-Meier and Cox regression analysis using the change from normal ALT to elevated ALT as endpoints were performed to determine factors associated with ALT elevation/normalization. Seventy-four HBeAg-negative and 32 HBeAg-positive patients were prospectively evaluated. For HBeAg-negative patients, hepatitis B virus (HBV) DNA was predictive of future ALT. Only 1 patient with normal ALT and an HBV DNA value lower than 10,000 copies/mL developed an elevated ALT within the subsequent year, whereas 67% with an HBV DNA value greater than 100,000 copies/mL had a rise in ALT above normal within 1 year. Patients with a previous history of ALT elevation and longer follow-up at all levels of HBV DNA were more likely to experience ALT elevations. For HBeAg-negative patients with elevated ALT and all HBeAg-positive patients, HBV DNA did not predict future ALT. Other viral and host factors were not predictive of future ALT.

Conclusion:

HBeAg-negative CHB has a fluctuating course. HBV DNA values lower than 10,000 copies/mL predict persistently normal ALT for at least 1 year. Patients with HBV DNA values between 10,000 and 100,000 copies/mL can safely be followed at 6 monthly intervals, whereas HBV DNA values greater than 100,000 copies/mL are highly predictive of future ALT elevation and should prompt regular follow-up. (HEPATOLOGY 2007.)
Insights in the regulation of cholesterol 7α-hydroxylase gene reveal a target for modulating bile acid synthesis
Authors: Mitro Nico , Godio Cristina , De Fabiani Emma , Scotti Elena , Galmozzi Andrea , Gilardi Federica , Caruso Donatella , Chacon Ana Belen Vigil , Crestani Maurizio
Published: July 2007

The transcription of the gene (

CYP7A1

) encoding cholesterol 7α-hydroxylase, a key enzyme in cholesterol homeostasis, is repressed by bile acids via multiple mechanisms involving members of the nuclear receptor superfamily. Here, we describe a regulatory mechanism that can be exploited for modulating bile acid synthesis. By dissecting the mechanisms of

CYP7A1

transcription, we found that bile acids stimulate the sequential recruitment of the histone deacetylases (HDACs) 7, 3, and 1, and of the corepressor SMRTα (silencing mediator of retinoid and thyroid receptors-α) and the nuclear corepressor. Bile acids, but not the farnesoid X receptor–selective agonist GW4064, increase the nuclear concentration of HDAC7, which promotes the assembly of a repressive complex that ultimately represses

CYP7A1

transcription. Interestingly, despite its high basal expression level, small heterodimer partner (SHP) is associated with the

CYP7A1

promoter only at a later stage of bile acid repression. Gene silencing with small interfering RNA confirms that HDAC7 is the key factor required for the repression of

CYP7A1

transcription, whereas knockdown of SHP does not prevent the down-regulation of

CYP7A1

. Administration of the HDAC inhibitors valproic acid or trichostatin A to genetically hypercholesterolemic mice increases Cyp7a1 messenger RNA and bile acid synthesis and consequently markedly reduces total plasma and low-density lipoprotein cholesterol.

Conclusion:

By using a combination of molecular, cellular, and animal models, our study highlights the importance of HDACs in the feedback regulation of

CYP7A1

transcription and identifies these enzymes as potential targets to modulate bile acid synthesis and for the treatment of hypercholesterolemia. (Hepatology 2007.)
Analysis of suspended sediment yields after low impact forest harvesting
Authors: Hotta Norifumi , Kayama Toshiya , Suzuki Masakazu
Published: July 2007

Disturbances to forest catchments have profound effects on the environment of headwater streams and have an impact on suspended sediment (SS) management. Forest harvesting is a dominant factor in increasing SS yields. Road construction, skidder activity and ploughing associated with harvesting cause serious soil disturbance that results in SS increases. However, few studies have shown whether harvesting itself increases SS yields. This study examined how harvesting influenced SS yields in a steep forested area. During harvesting, soil surface disturbance was prevented as much as possible by using skyline logging treatments and piling branches and leaves at selected locations in the watershed. Using these methods, the representative SS rating curve did not change significantly after harvesting. The results also show that the characteristics of SS transport were related to the SS source area, and reveal that the riparian zone/stream bank was a dominant SS source area at the study site. Annual SS yields did not increase despite increasing annual water yields after harvesting. The limited water capacity of the soil at the study site likely led to only slight differences in pre‐ and post‐harvest water discharge from heavy rainfall events. Most SS was transported during heavy rainfall events, and increases in SS yields were not detected after harvesting. We concluded that it is possible to prevent post‐harvest SS increases by performing careful, low‐impact harvesting procedures. Copyright © 2007 John Wiley & Sons, Ltd.
Electronic structure, chemical bonding, and geometry of pure and Sr‐doped CaCO3
Authors: Stashans Arvids , Chamba Gaston , Pinto Henry
Published: July 2007

The electronic structure, chemical bonding, geometry, and effects produced by Sr‐doping in CaCO3 have been studied on the basis of density‐functional theory using the VASP simulation package and molecular‐orbital theory utilizing the CLUSTERD computer code. Two calcium carbonate structures which occur naturally in anhydrous crystalline forms, calcite and aragonite, were considered in the present investigation. The obtained diagrams of density of states show similar patterns for both materials. The spatial structures are computed and analyzed in comparison to the available experimental data. The electronic properties and atomic displacements because of the trace element Sr‐incorporation are discussed in a comparative manner for the two crystalline structures. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
Effects of a gonadotropin‐releasing hormone antagonist on gonadotropin levels in masu salmon and sockeye salmon
Authors: Amano Masafumi , Ikuta Kazumasa , Kitamura Shoji
Published: July 2007

The salmon gonadotropin‐releasing hormone (sGnRH) is considered to be involved in gonadal maturation via gonadotropin (GTH) secretion in salmonid fishes. However, there is no direct evidence for endogenous sGnRH‐stimulated GTH secretion in salmonids. In this study, to clarify whether endogenous sGnRH stimulates GTH secretion, we examined the effects of the mammalian GnRH (mGnRH) antagonist [Ac‐Δ3‐Pro1, 4FD‐Phe2, D‐Trp3,6]‐mGnRH on luteinizing hormone (LH) levels in 0‐year‐old masu salmon Oncorhynchus masou and sockeye salmon Oncorhynchus nerka. First, the effects of the GnRH antagonist on LH release were examined in 0‐year‐old precocious male masu salmon. GnRH antagonist treatment for 3 hr significantly inhibited an increase in plasma LH levels that was artificially induced by exogenous sGnRH administration, indicating that the GnRH antagonist is effective in inhibiting LH release from the pituitary. Subsequently, we examined the effect of the GnRH antagonist on LH synthesis in 0‐year‐old immature sockeye salmon that were pretreated with exogenous testosterone for 42 days to increase the pituitary LH contents; the testosterone treatment did not affect the plasma LH levels. GnRH antagonist treatment slightly but significantly inhibited an increase in the testosterone‐stimulated pituitary LH content levels. However, no significant differences in the plasma LH levels were observed between the GnRH antagonist‐treated and control groups. These results suggest that endogenous sGnRH is involved in LH secretion in salmonid fishes. J. Exp. Zool. 307A:535–541, 2007. © 2007 Wiley‐Liss, Inc.
Structural and transfection properties of amine‐substituted gemini surfactant‐based nanoparticles
Authors: Wettig Shawn D. , Badea Ildiko , Donkuru McDonald , Verrall Ronald E. , Foldvari Marianna
Published: July 2007

Background

Increases in DNA transfection efficiencies for non‐viral vectors can be achieved through rational design of novel cationic building blocks. Based on previous results examining DNA condensation by polyamines, novel gemini surfactants have been designed that incorporate aza or imino substituents within the spacer group in order to increase interactions with DNA and potentially improve their DNA transfection ability.

Methods

Transfection efficiencies and cell toxicity of gemini nanoparticles constructed from plasmid DNA, gemini surfactant, and a neutral lipid were measured in COS7 cells using a luciferase assay. Structural properties of nanoparticles were examined by using circular dichroism, particle size, zeta potential, and small‐angle X‐ray scattering (SAXS) measurements.

Results

The incorporation of aza and imino substituents within the spacer group was observed to enhance the transfection ability of gemini surfactants. Incorporation of an imino group in the structure of the 1,9‐bis(dodecyl)‐1,1,9,9‐tetramethyl‐5‐imino‐1,9‐nonanediammonium dibromide surfactant (12‐7NH‐12) resulted in a statistically significant (p < 0.01) 9‐fold increase in transfection compared to an unsubstituted gemini surfactant and a 3‐fold increase compared to the corresponding aza‐substituted compound. A pH‐dependent transition in size and zeta potential was observed to occur at pH 5.5 for complexes formed from the 12‐7NH‐12 compound. SAXS results show weakly ordered structures and the presence of multiple phases.

Conclusions

The incorporation of a pH‐active imino group within the spacer of the gemini surfactant results in a significant increase in transfection efficiency that can be related to both pH‐induced changes in nanoparticle structure and the formation of multiple phases that more readily allow for membrane fusion that may facilitate DNA release. Copyright © 2007 John Wiley & Sons, Ltd.
Quantitative assessment of ventricular function using three‐dimensional SSFP magnetic resonance angiography
Authors: Greil Gerald F. , Boettger Thomas , Germann Sabrina , Klumpp Bernhard , Baltes Christof , Kozerke Sebastian , Bialkowski Anja , Urschitz Michael S. , Miller Stephan , Wolf Ivo , Meinzer Hans‐Peter , Sieverding Ludger
Published: July 2007

Purpose

To evaluate three‐dimensional (3D), free‐breathing, steady‐state free precession (SSFP) magnetic resonance angiography (MRA) for volumetric assessment of ventricular function.

Materials and Methods

In 18 subjects (mean age = 21.5 years) 3D datasets of the heart and great vessels were acquired using an ECG‐triggered, free‐breathing SSFP technique with a T2‐preparation prepulse. Data were acquired during end‐systole (ES) and end‐diastole (ED) for assessment of stroke volumes (SVs). Through‐plane flow measurements of the great arteries were performed as well as 2D‐cine SSFP imaging for comparison. For image analysis of the 3D SSFP datasets a simplex mesh model was used. Papillary muscles were excluded from ventricular volumes using thresholds. Intra‐ and interobserver variability (Bland‐Altman analysis) and correlations (Pearson's coefficient) between volumetric and flow measurements were assessed.

Results

ES and ED datasets were acquired successfully in all subjects. The best correlation was observed between flow vs. 3D SSFP SV for the LV (r = 0.85, mean difference = −1.0 mL) and the RV (r = 0.89, mean difference = −2.2 mL) with high intra‐ (LV: r = 0.93; RV: r = 0.94) and interobserver (LV: r = 0.91; RV: r = 0.93) reproducibility.

Conclusion

3D SSFP datasets combined with semiautomatic segmentation algorithms allow highly accurate and reproducible assessment of left (LV) and right ventricular (RV) SVs in free‐breathing subjects. J. Magn. Reson. Imaging 2007;26:288–295. © 2007 Wiley‐Liss, Inc.
SAR and temperature: Simulations and comparison to regulatory limits for MRI
Authors: Wang Zhangwei , Lin James C. , Mao Weihua , Liu Wanzhan , Smith Michael B. , Collins Christopher M.
Published: July 2007

Purpose

To present and discuss numerical calculations of the specific absorption rate (SAR) and temperature in comparison to regulatory limits. While it is possible to monitor whole‐body or whole‐head average SAR and/or core body temperature during MRI in practice, this is not generally true for local SAR values or local temperatures throughout the body. While methods of calculation for SAR and temperature are constantly being refined, methods for interpreting results of these calculations in light of regulatory limits also warrant discussion.

Materials and Methods

Numerical calculations of SAR and temperature for the human head in a volume coil for MRI at several different frequencies are presented.

Results

Just as the field pattern changes with the frequency, so do the temperature distribution and the ratio of maximum local SAR (in 1‐g or 10‐g regions) to whole‐head average SAR. In all of the cases studied here this ratio is far greater than that in the regulatory limits, indicating that existing limits on local SAR will be exceeded before limits on whole‐body or whole‐head average SAR are reached.

Conclusion

Calculations indicate that both SAR and temperature distributions vary greatly with B1 field frequency, that temperature distributions do not always correlate well with SAR distributions, and that regulatory limits on local temperature may not be exceeded as readily as those on local SAR. J. Magn. Reson. Imaging 2007;26:437–441. © 2007 Wiley‐Liss, Inc.
Evaluation of optimal echo time for 1H‐spectroscopic imaging of brain tumors at 3 Tesla
Authors: Hattingen Elke , Pilatus Ulrich , Franz Kea , Zanella Friedhelm E. , Lanfermann Heinrich
Published: July 2007

Purpose

To compare the spectral quality of short echo time (TE) MR spectroscopic imaging (MRSI, TE = 30 msec) with long‐TE MRSI (TE = 144 msec) at 3 Tesla in normal brain and tumor tissue.

Materials and Methods

Spectroscopic imaging (chemical‐shift imaging (CSI)) data of 32 patients with histopathological confirmed brain lesions were acquired at 3 Tesla (3T) using TEs of 30 msec and 144 msec. Tumor‐relevant metabolites (trimethylamine (TMA), creatine compounds (tCr), and N‐acetylated compounds (tNAA)) were analyzed with LCModel software, which applies prior knowledge by performing a frequency domain fit using a linear combination of model spectra.

Results

Short‐TE spectra provided up to twice the signal‐to‐noise ratio (SNR) compared to TE = 144 msec. The estimated fitting error was improved up to 30% for TMA and tCr, but was slightly reduced (10%) for tNAA. Quantification in terms of absolute concentrations was consistent at both TEs.

Conclusion

Since other metabolites observable at TE < 30 msec may be of diagnostic relevance, short‐TE MRSI should be the preferred method at 3T for the evaluation of focal lesions in brain tissue; however, TE = 144 msec can serve as an option for MRS in regions with potential baseline problems. J. Magn. Reson. Imaging 2007;26:427–431. © 2007 Wiley‐Liss, Inc.
Accuracy of blood flow values determined by arterial spin labeling: A validation study in isolated porcine kidneys
Authors: Warmuth Carsten , Nagel Stefan , Hegemann Oliver , Wlodarczyk Waldemar , Lüdemann Lutz
Published: July 2007

Purpose

To validate the accuracy of quantitative blood flow values determined using pulsed arterial spin labeling (ASL) in the preserved and reperfused porcine kidney.

Materials and Methods

Ex vivo porcine kidneys were perfused with whole blood under physiological conditions, in particular including pulsatile flow. Total flow through the kidney was determined using an ultrasound flowmeter. ASL measurements at two different inversion times and four different flow rates in the range of 70–210 mL/100 mL*minute were performed. Absolute values of blood flow and arterial transit times were determined in the kidney cortex.

Results

The quantitative values were in good agreement with the reference values obtained after calibration of the total flow. The greatest difference observed was 13%.

Conclusion

Isolated organ hemoperfusion allows validating perfusion imaging techniques. The experimental setup enables long‐term radiotherapeutic or toxicological studies using noninvasive ASL to monitor blood flow quantitatively. J. Magn. Reson. Imaging 2007;26:353–358. © 2007 Wiley‐Liss, Inc.
Establishing a baseline phase behavior in magnetic resonance imaging to determine normal vs. abnormal iron content in the brain
Authors: Haacke E. Mark , Ayaz Muhammad , Khan Asadullah , Manova Elena S. , Krishnamurthy Bharani , Gollapalli Lakshman , Ciulla Carlo , Kim I. , Petersen Floyd , Kirsch Wolff
Published: July 2007

Purpose

To establish a baseline of phase differences between tissues in a number of regions of the human brain as a means of detecting iron abnormalities using magnetic resonance imaging (MRI).

Materials and Methods

A fully flow‐compensated, three‐dimensional (3D), high‐resolution, gradient‐echo (GRE) susceptibility‐weighted imaging (SWI) sequence was used to collect magnitude and phase data at 1.5T. The phase images were high‐pass‐filtered and processed region by region with hand‐drawn areas. The regions evaluated included the motor cortex (MC), putamen (PUT), globus pallidus (GP), caudate nucleus (CN), substantia nigra (SN), and red nucleus (RN). A total of 75 subjects, ranging in age from 55 to 89 years, were analyzed.

Results

The phase was found to have a Gaussian‐like distribution with a standard deviation (SD) of 0.046 radians on a pixel‐by‐pixel basis. Most regions of interest (ROIs) contained at least 100 pixels, giving a standard error of the mean (SEM) of 0.0046 radians or less. In the MC, phase differences were found to be roughly 0.273 radians between CSF and gray matter (GM), and 0.083 radians between CSF and white matter (WM). The difference between CSF and the GP was 0.201 radians, and between CSF and the CN (head) it was 0.213 radians. For CSF and the PUT (the lower outer part) the difference was 0.449 radians, and between CSF and the RN (third slice vascularized region) it was 0.353 radians. Finally, the phase difference between CSF and SN was 0.345 radians.

Conclusion

The Gaussian‐like distributions in phase make it possible to predict deviations from normal phase behavior for tissues in the brain. Using phase as an iron marker may be useful for studying absorption of iron in diseases such as Parkinson's, Huntington's, neurodegeneration with brain iron accumulation (NBIA), Alzheimer's, and multiple sclerosis (MS), and other iron‐related diseases. The phases quoted here will serve as a baseline for future studies that look for changes in iron content. J. Magn. Reson. Imaging 2007;26:256–264. © 2007 Wiley‐Liss, Inc.
Micellization and the Surface Hydrophobicity of Amphiphilic Poly(vinylphenol)‐block‐Polystyrene Block Copolymers
Authors: Tung Pao‐Hsaing , Kuo Shiao‐Wei , Chan Shih‐Chien , Hsu Chih‐Hao , Wang Chih‐Feng , Chang Feng‐Chih
Published: July 2007

The self‐assembly of PVPh‐b‐PS in different solvents was studied. Upon replacing toluene by THF as the solvent, the morphology of the resulting aggregates change from core‐shell spheres, rod‐like micelles and vesicles to onion‐like aggregates. With increasing block copolymer concentration, morphologies such as honeycomb‐like films, surfaces of aggregated large porous spheres, or pincushion‐like spheres with protruding tubular vesicle aggregates are observed. These surface‐patterned films show significantly enhanced hydrophobicity. The results suggest that a superhydrophobic behavior can be achieved, with a maximum contact angle of 158°, by using the pincushion‐like micellar structure.

magnified image
Hyperbranched Poly(p‐phenylene ethynylene)s
Authors: Mendez James D. , Schroeter Michael , Weder Christoph
Published: July 2007

Hyperbranched poly(p‐phenylene ethynylenes) (HB‐PPEs) were synthesized in an A2 + B3one‐pot approach by the Pd/Cu‐catalyzed cross‐coupling reaction of 1,4‐diethynyl‐2,5‐bis‐(octyloxy)benzene and 1,2,4‐tribromobenzene. Reaction conditions were varied with the objective to obtain well‐defined HB‐PPEs of different molecular weights. HB‐PPEs with$\overline M _{\rm w}$from 11 000 to 237 000 g · mol−1and PDIs of 1.5–10.7 were prepared. All polymers that comprised unreacted ethynyl groups eventually became insoluble upon drying, presumably as a result of solid‐state cross‐linking. This reaction could be prevented by endcapping the polymers with an excess of 4‐iodotoluene.

magnified image
Functionalized Thermo‐Responsive Poly(vinyl ether) by Living Cationic Random Copolymerization of Methyl Vinyl Ether and 2‐Chloroethyl Vinyl Ether
Authors: Confortini Ondine , Du Prez Filip E.
Published: July 2007

The living cationic random copolymerization of MVE and CEVE to obtain functionalized thermo‐responsive PMVE as precursors for more complex PMVE‐containing polymer structures is reported. The random copolymers P(MVE‐co‐CEVE) were synthesized at 0 °C in toluene using the DEE/TMSI/ZnI2 initiating system. The monomer reactivity ratios of these copolymers are determined according to the extended Kelen‐Tüdõs procedure: rCEVE = 0.48 ± 0.04 and rMVE = 0.76 ± 0.05. The cloud point temperatures of the random copolymers are found to depend strongly on the composition of the copolymer and disappeared at CEVE contents above 3 mol‐%.

magnified image