bluuebunny/crossref_metadata_2025 huggingface dataset:
Scaling down the Perdew-Zunger self-interaction correction in many-electron regions
Authors: Vydrov Oleg A. , Scuseria Gustavo E. , Perdew John P. , Ruzsinszky Adrienn , Csonka Gábor I.
Published: March 2006

Semilocal density functional approximations (DFAs) for the exchange-correlation energy suffer from self-interaction error, which is believed to be the cause of many of the failures of common DFAs, such as poor description of charge transfer and transition states of chemical reactions. The standard self-interaction correction (SIC) of Perdew and Zunger mends some of these failures but spoils such essential properties as thermochemistry and equilibrium bond lengths. The Perdew-Zunger SIC seems to overcorrect many-electron systems. In this paper, we propose a modified SIC, which is scaled down in many-electron regions. The new SIC has an improved performance for many molecular properties, including total energies, atomization energies, barrier heights of chemical reactions, ionization potentials, electron affinities, and bond lengths. The local spin-density approximation (LSDA) benefits from SIC more than higher-level functionals do. The scaled-down SIC has only one adjustable parameter. Rationalization of the optimal value of this parameter enables us to construct an almost-nonempirical version of the scaled-down SIC-LSDA, which is significantly better than uncorrected LSDA and even better than the uncorrected generalized gradient approximation. We present an analysis of the formal properties of the scaled-down SIC and define possible directions for further improvements. In particular, we find that exactness for all one-electron densities does not guarantee correct asymptotics for the exchange-correlation potential of a many-electron system.
Weak localization in ultrananocrystalline diamond
Authors: Mareš J. J. , Hubík P. , Krištofik J. , Kindl D. , Fanta M. , Nesládek M. , Williams O. , Gruen D. M.
Published: March 2006

In this letter we present results of magnetotransport measurements, carried out on heavily nitrogen-doped ultrananocrystalline diamond films, prepared by plasma-enhanced chemical vapor deposition. This material having at room temperature appreciably high electric conductivity (∼4200Sm−1) revealed surprisingly at Kelvin temperatures a giant negative magnetoresistance reaching up to 22% at 1.28K and at 8T. The analysis of experimental data has borne evidence of the fact that the transport in this subsystem has a character of low-dimensional disordered metal and it is controlled by quantum interference effects of electrons resulting in their weak localization.
Hydrogen-vacancy related defect in chemical vapor deposition homoepitaxial diamond films studied by electron paramagnetic resonance and cathodoluminescence
Authors: Mizuochi N. , Watanabe H. , Okushi H. , Yamasaki S. , Niitsuma J. , Sekiguchi T.
Published: March 2006

Hydrogen-vacancy related defect (H1′) in chemical vapor deposition homoepitaxial diamond films has been investigated by electron paramagnetic resonance and cathodoluminescence. It is found that the concentration of H1′ significantly decreases as the dilution (CH4∕H2) ratio decreases. It is also confirmed that the intensity of free-exciton emission (Iex) increases as the CH4∕H2 ratio decreases. The complementary relationship between Iex and H1′ can be explained by considering that H1′ acts as a nonradiative recombination center which reduces the lifetime of free exciton and Iex. The suppression mechanism of H1′ is discussed by considering the balance between the growth rate and the annihilation rate of H1′ in the subsurface region.
Patterned growth and cathodoluminescence of conical boron nitride nanorods
Authors: Zhang H. Z. , Phillips M. R. , Fitz Gerald J. D. , Yu J. , Chen Y.
Published: March 2006

We demonstrate a simple and effective approach for growing large-scale, high-density, and well-patterned conical boron nitride nanorods. A catalyst layer of Fe(NO3)3 was patterned on a silicon substrate by using a copper grid as a mask. The nanorods were grown via annealing milled boron carbide powders at 1300°C in a flow of nitrogen gas. The as-grown nanorods exhibit uniform morphology and the catalyst pattern precisely defines the position of nanorod deposition. Cathodoluminescence (CL) spectra of the nanorods show two broad emission bands centered at 3.75 and 1.85eV. Panchromatic CL images reveal clear patterned structure.
High power, single-mode operation from photonic-lattice semiconductor lasers with controllable lateral resonance
Authors: Li Shuang , Xu Dapeng , Botez Dan
Published: March 2006

An active-photonic-crystal (APC) laser based on laterally resonant arrays of antiguides is proposed and demonstrated. Approximately 1-μm-wide, high-index APC sites are obtained by preferential etching and GaAs regrowth into a GaAs∕InGaP∕AlGaAs base structure. For 4-μm-wide, low-index APC sites ∼0.28-μm-thick regrowths provide resonant leaky-wave coupling across a 100-μm-wide aperture (i.e., across a 20-element APC structure) at 0.98μm vacuum wavelength. Large intermodal discrimination favoring in-phase mode operation to high drive levels is obtained at and around the in-phase mode resonance by introducing significant nonsaturatable losses in the high-index sites. The lateral-resonance condition is controlled during fabrication via small variations in the preferential-regrowths thickness on several pieces from the same wafer base. Virtually single-lobe, near-diffraction-limited beam operation is obtained up to 1.1W peak power at 11 times threshold. This also represents the demonstration of the lateral component needed for the realization of two-dimensional (2D) grating surface-emitting, single-mode APC lasers.
Increased O(D1) metastable density in highly Ar-diluted oxygen plasmas
Authors: Kitajima Takeshi , Nakano Toshiki , Makabe Toshiaki
Published: March 2006

Enhancement of the growth rate of SiO2 with a rare gas diluted O2 plasma is of interest for application to various microelectronics fabrications. The key is the oxygen metastable atom (D1) density, which has the potential for surface activation. We used vacuum ultraviolet optical absorption spectroscopy to detect O(D1) and found a twofold increase in the density of O(D1) due to the dilution with Ar. The density increase is reasonably explained by the increase of the electron density, the oxygen dissociation fraction, and the Ar metastable density, that are experimentally obtained for low O2 fractions.
High-power λ∼9.5μm quantum-cascade lasers operating above room temperature in continuous-wave mode
Authors: Yu J. S. , Slivken S. , Evans A. , Darvish S. R. , Nguyen J. , Razeghi M.
Published: March 2006

We report high-power continuous-wave (cw) operation of λ∼9.5μm quantum-cascade lasers to a temperature of 318K. A high-reflectivity-coated 19-μm-wide and 3-mm-long device exhibits cw output powers as high as 150mW at 288K and still 22mW at 318K. In cw operation at 298K, a threshold current density of 1.57kA∕cm2, a slope efficiency of 391mW∕A, and a maximum wall-plug efficiency of 0.71% are obtained. In pulsed operation, a maximum average power of 317mW is achieved at 49% duty cycle. The emission wavelength in cw mode is shifted from 9.524μm at 288K to 9.547μm at 313K near 1.05A drive current with a temperature tuning coefficient of 0.92nm∕K.
Single mode photonic crystal vertical cavity lasers
Authors: Danner Aaron J. , Raftery James J. , Leisher Paul O. , Choquette Kent D.
Published: March 2006

We report the accuracy of the photonic crystal model in describing the characteristics of vertical cavity surface-emitting lasers with lateral optical confinement consisting of a periodic array of etched circular holes. Experiments were carried out to compare predictions of the photonic crystal model to observed modal device characteristics, and the oxide aperture size was optimized to give maximum output power and lower threshold. The role of loss in improving modal properties was also investigated. Optimized lasers exhibit submilliamp threshold current and operate in the fundamental lateral mode for all currents.
Shear-strain-governed transient compressive response of electrorheological fluid
Authors: Tian Yu , Meng Yonggang , Wen Shizhu
Published: March 2006

Transient process of electrorheological (ER) fluids compressed between two parallel plates and applied a high square-wave voltage has been modeled based on transient shear strain constant and shear stress and experimentally verified. The transient compressive resistance is integrated from the pressure distribution at the middle plane between the plates. Employing transient shear strain constant derived from other experimental investigations of dynamic shearing of ER fluids to fit the tested compressive stress, good results have been obtained. The rising of compressive stress upon the sudden applying of an electric field showed to be governed by the experienced shear strain of the compressed ER fluid.
Ultimate efficiency of polymer/fullerene bulk heterojunction solar cells
Authors: Koster L. J. A. , Mihailetchi V. D. , Blom P. W. M.
Published: March 2006

We present model calculations to explore the potential of polymer/fullerene bulk heterojunction solar cells. As a starting point, devices based on poly(3-hexylthiophene) and 6,6-phenyl C61-butyric acid methyl ester (PCBM), reaching 3.5% efficiency, are modeled. Lowering the polymeric band gap will lead to a device efficiency exceeding 6%. Tuning the electronic levels of PCBM in such a way that less energy is lost in the electron transfer process enhances the efficiency to values in excess of 8%. Ultimately, with an optimized level tuning, band gap, and balanced mobilities polymeric solar cells can reach power conversion efficiencies approaching 11%.
Size-dependent crystallization of Si nanoparticles
Authors: Hirasawa Makoto , Orii Takaaki , Seto Takafumi
Published: March 2006

Crystallization temperature dependency on Si nanoparticles size was studied by using Raman scattering spectroscopy. Si nanoparticles synthesized by pulsed laser ablation were annealed at various temperatures while they were suspended in helium background gas, and then were classified by a differential mobility analyzer. After the size classification, Si nanoparticles showed a narrow size distribution which enabled investigation of the size-dependent crystallization. The temperature threshold for the transition from amorphous to crystalline (Tc) decreased as the particle size decreased: the Tc values of the 10, 8, 6, and 4nm particles were 1273, 1173, 1073 and 773K, respectively.
Fabrication and characterization of two-pole X-band HgBa2CaCu2O6+δ microstrip filters
Authors: Dizon Jonathan R. , Zhao Hua , Baca Javier , Mishra Shramana , Emergo Rose Lyn , Aga Roberto S. , Wu Judy Z.
Published: March 2006

Hg Ba 2 Ca Cu 2 O 6 + δ (Hg-1212) two-pole X-band microstrip filters of 5% 3dB bandwidth have been fabricated and evaluated. The Hg-1212 filters exhibited a 449±3MHz bandwidth and a center frequency of 10.86±0.02GHz below the superconducting temperature Tc of 121K with low insertion loss of 0.70±0.04dB at 110K. This performance represents the best so far achieved in superconductor filters at above 100K. The better performance of the Hg-1212 filter at higher temperatures, as compared to its YBa2Cu3O7 and Cu counterparts at 77K, was attributed mainly to its higher Tc, which makes Hg-1212 a promising alternative material for passive microwave devices.
Increasing leaf export and grain import capacities in maize plants under water stress
Authors: Trouverie Jacques , Prioul Jean-Louis
Published: March 2006

The export rate and the carbohydrate concentration were measured in maize plants submitted to water deprivation either at the fourth leaf stage or at pollination. Export rate was evaluated by a short pulse of labelling with 14CO2 followed by a 10-h chase. In stressed plants, 14C fixation was strongly reduced. When radioactivity was expressed relative to the initial value, the time course of label export from the labelled zone showed a faster decline in stressed plants than in well-watered plants. This was observed both under mild stress (fourth leaf stage) and severe stress (pollination stage). Another consequence of drought stress was an increase in fourth leaf vacuolar invertase activity and an increase in hexoses, which accumulated to the same content as sucrose. This occurred without a significant decrease in starch. At pollination stage, despite a large decrease in absolute quantity of 14C entering kernels, the proportion of leaf 14C export recovered in the kernel was not modified after a 4-d water deprivation, i.e. at day 0 after pollination (0 DAP), and was multiplied by a factor of 2–3 at 12 DAP. The major conclusion arising from these data appears to be an improvement of both leaf export and kernel import efficiency under water stress.
Tumor suppressor PTEN acts through dynamic interaction with the plasma membrane
Authors: Vazquez Francisca , Matsuoka Satomi , Sellers William R. , Yanagida Toshio , Ueda Masahiro , Devreotes Peter N.
Published: March 2006

The tumor suppressor function of PTEN is strongly linked to its ability to dephosphorylate phosphatidylinositol-3,4,5 trisphosphate and, thereby, control cell growth, survival, and migration. However, the mechanism of action of PTEN in living cells is largely unexplored. Here we use single-molecule TIRF microscopy in living cells to reveal that the enzyme binds to the membrane for a few hundred milliseconds, sufficient to degrade several phosphatidylinositol-3,4,5 trisphosphate molecules. Deletion of an N-terminal lipid-binding motif completely abrogates membrane interaction and
in vivo
function. Several mechanisms, including C-terminal tail phosphorylations, appear to hold PTEN in a constrained conformation that limits its rate of association with the membrane. The steady-state level of bound PTEN is highest at sites of retracting membrane, including the rear of highly polarized cells. The dynamic membrane association could be modulated temporally or spatially to alter PTEN activity in specific physiological situations and could have important implications for tumor suppressor function.
Familial clustering of site-specific cancer risks associated with BRCA1 and BRCA2 mutations in the Ashkenazi Jewish population
Authors: Simchoni Sharon , Friedman Eitan , Kaufman Bella , Gershoni-Baruch Ruth , Orr-Urtreger Avi , Kedar-Barnes Inbal , Shiri-Sverdlov Ronit , Dagan Efrat , Tsabari Sigal , Shohat Mordechai , Catane Raphael , King Mary-Claire , Lahad Amnon , Levy-Lahad Ephrat
Published: March 2006

Inherited mutations in BRCA1 and BRCA2 lead to significantly increased risks of breast and ovarian cancer. We used epidemiologic methods to evaluate the relative risks of breast cancer vs. ovarian cancer among women of Ashkenazi Jewish ancestry with inherited mutations in BRCA1 or BRCA2. The cancer of a family's index case (i.e., breast cancer vs. ovarian cancer) was significantly associated with site-specific risks of cancer in relatives known to carry mutations in BRCA1 or BRCA2. Specifically, breast cancer risks were higher among relatives of breast cancer index cases compared with relatives of ovarian cancer index cases [hazard ratio (HR) = 3.0,
P
< 0.001 for BRCA1 carriers and HR = 4.8,
P
= 0.017 for BRCA2 carriers], and ovarian cancer risks were higher among relatives of ovarian cancer index cases compared with relatives of breast cancer index cases (HR = 7.2,
P
= 0.001 for BRCA1 carriers and HR = 15.8,
P
= 0.018 for BRCA2 carriers). Breast and ovarian cancer risks also increased with more recent year of birth. For each later decade of birth, risk increased 1.2-fold (
P
= 0.03). Effects of cancer site of the index case and of birth cohort were independent. These results suggest that both genetic and nongenetic factors modify cancer risks among BRCA1 and BRCA2 mutation carriers, and that genetic modifiers and other familial factors may influence risk specifically for either breast or ovarian cancer.
Cyclosporin and Timothy syndrome increase mode 2 gating of CaV1.2 calcium channels through aberrant phosphorylation of S6 helices
Authors: Erxleben Christian , Liao Yanhong , Gentile Saverio , Chin David , Gomez-Alegria Claudio , Mori Yasuo , Birnbaumer Lutz , Armstrong David L.
Published: March 2006

Calcium channels in the plasma membrane rarely remain open for much more than a millisecond at any one time, which avoids raising intracellular calcium to toxic levels. However, the dihydropyridine-sensitive calcium channels of the CaV1 family, which selectively couple electrical excitation to endocrine secretion, cardiovascular contractility, and neuronal transcription, have a unique second mode of gating, “mode 2,” that involves frequent openings of much longer duration. Here we report that two human conditions, cyclosporin neurotoxicity and Timothy syndrome, increase mode 2 gating of the recombinant rabbit CaV1.2 channel. In each case, mode 2 gating depends on a Ser residue at the cytoplasmic end of the S6 helix in domain I (Ser-439, Timothy syndrome) or domain IV (Ser-1517, cyclosporin). Both Ser reside in consensus sequences for type II calmodulin-dependent protein kinase. Pharmacologically inhibiting type II calmodulin-dependent protein kinase or mutating the Ser residues to Ala prevents the increase in mode 2 gating. We propose that aberrant phosphorylation, or “phosphorylopathy,” of the CaV1.2 channel protein contributes to the excitotoxicity associated with Timothy syndrome and with chronic cyclosporin treatment of transplant patients.
Quorum sensing and motility mediate interactions between
Pseudomonas aeruginosa
and
Agrobacterium tumefaciens
in biofilm cocultures
Authors: An Dingding , Danhorn Thomas , Fuqua Clay , Parsek Matthew R.
Published: March 2006

In the environment, multiple microbial taxa typically coexist as communities, competing for resources and, often, physically associated within biofilms. A dual-species cocultivation model has been developed by using two ubiquitous and well studied microbes
Pseudomonas aeruginosa
(
P.a.
) and
Agrobacterium tumefaciens
(
A.t.
) as a tractable system to identify molecular mechanisms that underlie multispecies microbial associations. Several factors were found to influence coculture interactions.
P.a.
had a distinct growth-rate advantage in cocultures, increasing its relative abundance during planktonic and biofilm growth.
P.a.
also demonstrated a slight quorum-sensing-dependent increase in growth yield in liquid cocultures.
P.a.
dominated coculture biofilms, “blanketing” or burying immature
A.t.
microcolonies.
P.a.
flagellar and type IV pili mutant strains exhibited deficient blanketing and impaired competition in coculture biofilms, whereas, in planktonic coculture, these mutations had no effect on competition. In contrast,
A.t.
used motility to emigrate from coculture biofilms. In both planktonic and biofilm cocultures,
A.t.
remained viable for extended periods of time, coexisting with its more numerous competitor. These findings reveal that quorum-sensing-regulated functions and surface motility are important microbial competition factors for
P.a.
and that the outcome of competition and the relative contribution of different factors to competition are strongly influenced by the environment in which they occur.
Initiation of shape-memory effect by inductive heating of magnetic nanoparticles in thermoplastic polymers
Authors: Mohr R. , Kratz K. , Weigel T. , Lucka-Gabor M. , Moneke M. , Lendlein A.
Published: March 2006

In shape-memory polymers, changes in shape are mostly induced by heating, and exceeding a specific switching temperature,Tswitch. If polymers cannot be warmed up by heat transfer using a hot liquid or gaseous medium, noncontact triggering will be required. In this article, the magnetically induced shape-memory effect of composites from magnetic nanoparticles and thermoplastic shape-memory polymers is introduced. A polyetherurethane (TFX) and a biodegradable multiblock copolymer (PDC) with poly(p-dioxanone) as hard segment and poly(ε-caprolactone) as soft segment were investigated as matrix component. Nanoparticles consisting of an iron(III)oxide core in a silica matrix could be processed into both polymers. A homogeneous particle distribution in TFX could be shown. Compounds have suitable elastic and thermal properties for the shape-memory functionalization. Temporary shapes of TFX compounds were obtained by elongating at increased temperature and subsequent cooling under constant stress. Cold-drawing of PDC compounds at 25°C resulted in temporary fixation of the mechanical deformation by 50–60%. The shape-memory effect of both composite systems could be induced by inductive heating in an alternating magnetic field (f= 258 kHz;H= 30 kA·m−1). The maximum temperatures achievable by inductive heating in a specific magnetic field depend on sample geometry and nanoparticle content. Shape recovery rates of composites resulting from magnetic triggering are comparable to those obtained by increasing the environmental temperature.
Echocardiographic Characterization of the Cardiovascular Phenotype in Rodent Models
Authors: Hoit Brian D.
Published: March 2006

Echocardiographic techniques are commonly utilized to describe the rodent cardiovascular phenotype. These approaches are contrasted with other in vivo methods and are positioned in the assay selection process by a review of studies from our laboratory and others. Although not conventionally considered a biomarker, the technique has the potential to be exploited as a marker of intentional or unanticipated toxic biological effects in the preclinical development of drugs and chemicals.
Standard Morphologic Evaluation of the Heart in the Laboratory Dog and Monkey
Authors: Keenan Charlotte M. , Vidal Justin D.
Published: March 2006

The nonrodent species most commonly utilized in preclinical safety studies are the purpose-bred beagle dog and cynomolgus macaque ( Macaca fascicularis). Potential effects of a new chemical entity (NCE) on the heart pose serious concerns; consequently in vivo testing is focused on detection of functional alterations as well as morphological changes. Macroscopic and microscopic evaluation of the heart is based on a standard survey of key structures to properly assess presence of spontaneous and potential drug-induced lesions. Evaluation of historical controls to determine type and frequency of background change is valuable, as studies with non-rodent species generally have a small sample size. Archived control dog and monkey data were retrospectively reviewed, including terminal body weight (BW), heart weight (HW), and archival glass slides of heart. Control dogs had minimal background changes that included myxomatous or cartilagenous change in the cardiac skeleton and a variable degree of vacuolation in Purkinje fibers. Control monkey hearts commonly contained inflammatory cell infiltrates, myocyte anisokaryosis, and handling artifacts, while myocyte degeneration, squamous plaques, pigment, and intimal plaques were occasionally observed. These findings highlight the utility of consistently recorded and readily accessible archived control data when attempting to discern background spontaneous changes and artifacts from test-article induced changes.
Clinical Biomarkers of Cardiac Injury: Cardiac Troponins and Natriuretic Peptides
Authors: Apple Fred S.
Published: March 2006

Laboratory and clinical medicine groups are actively collaborating and optimizing their individual expertise to potentially prove standardized biomarker assays that will optimize patient care. It is critical as new biomarkers are discovered, that quality specifications be developed prior to approval by regulatory agencies that give supported endorsement for the worldwide marketplace. The laboratory medicine and clinical communities of scientists continues to challenge the biomarker field, working towards developing standard reference materials, and providing quality analytical specifications that, hopefully, will be endorsed by our clinical, in vitro diagnostic and pharmaceutical industry colleagues. This paper will specifically address cardiac troponins and natriuretic peptides.
Acute Drug-Induced Vascular Injury in Beagle Dogs: Pathology and Correlating Genomic Expression
Authors: Enerson Bradley E. , Lin Aiping , Lu Bin , Zhao Hongyu , Lawton Michael P. , Floyd Eugenia
Published: March 2006

Acute vascular injury that leads to vascular inflammation is a common finding in the preclinical toxicity testing of drugs in rats and dogs. However, the relevance of this finding for risk to humans is unclear. Concern about the safety of these drugs is heightened by the current lack of noninvasive clinical methods to predict the onset of vascular damage in animals or humans. Determining the relevance of this poorly understood preclinical outcome for humans requires a better understanding of the molecular mechanisms of injury in addition to the development of sensitive and specific leading biomarkers for the clinical diagnosis of acute vascular damage.

Most molecular research on this toxicity has been performed in rats, but recent development of canine gene expression microarrays makes transcriptomic studies now possible in the dog. In this study, we investigated the molecular mechanisms of drug-induced vascular injury in dogs using gene arrays. After treating Beagles with toxic doses of CI-947, an adenosine receptor agonist, we profiled gene expression in the coronary arteries and correlated those changes with histopathology at 16 and 24 hours after dosing. The results demonstrated that pathobiological processes such as stimulation of the innate immune response, increased extracellular matrix turnover and oxidative stress were active at times of very early injury.
Biomarkers and Mechanisms of Drug-Induced Vascular Injury in Non-Rodents
Authors: Louden Calvert , Brott David , Katein Anne , Kelly Thomas , Gould Sarah , Jones Huw , Betton Graham , Valetin Jean-Pierre , Richardson Rudy J.
Published: March 2006

In preclinical safety studies, drug-induced vascular injury can negatively impact candidate-drug selection because there are no obvious diagnostic markers for monitoring this pathology preclinically or clinically. Furthermore, our current understanding of the pathogenesis of this lesion is limited. While vasodilatation and increased shear stress appear to play a role, the exact mechanism(s) of injury to the primary target cells, smooth muscle (SMC) and endothelial cell (EC), are unknown. Evaluation of potential novel markers for clinical monitoring with a mechanistic underpinning would add value in risk assessment and risk management. This mini review focuses on the efforts and progress to identify diagnostic markers as well as understanding the mechanism of action in nonrodent drug-induced vascular injury.
Serum Chemical Biomarkers of Cardiac Injury for Nonclinical Safety Testing
Authors: Walker Dana B.
Published: March 2006

There has been a substantial increase in the number and efficacy of laboratory biomarkers for the evaluation of human cardiac injury over the last decade. The advantages of these over traditional laboratory tests have encouraged adoption of comparable markers in nonclinical studies for cardiac injury assessment. Of particular interest are markers that are not only more sensitive and/or specific than traditional parameters for cardiac injury, but also those that may directly bridge human and laboratory animal safety testing. However, a majority of recently developed markers are quantified through antibody-based assays, and cross-reactivity with the comparable analyte in nonhuman samples is difficult to predict and often species-variable. The utility of these novel biomarkers thus, depends upon adequate assay validation with each laboratory species of interest. In contrast, traditional laboratory parameters of cardiac injury lack the properties of an ideal biomarker, but are well established and have an extensive database in nonclinical safety assessment. The current status and utility of both recently developed and traditional biomarkers of cardiac injury in nonclinical testing, and considerations for validation of novel biomarkers of cardiac injury are reviewed.
Portal vein stenosis and occlusion stenting after liver transplantation in two adults
Authors: Alfidja A. , Abergel A. , Chabrot P. , Pezet D. , Bony C. , Ravel A. , Garcier J. M. , Roche A. , Boyer L.
Published: March 2006

We report two cases of percutaneous transhepatic stenting of the portal vein to treat stenosis and occlusion disclosed 5 and 18 months, respectively, after orthotopic liver transplantation in two adult patients. If long-term patency is satisfactory, this technique should allow long-term management of portal vein stenosis and occlusion without the use of thrombolysis.
Standardized volume rendering for magnetic resonance angiography measurements in the abdominal aorta
Authors: Persson A. , Brismar T. B. , Lundström C. , Dahlström N. , Othberg F. , Smedby Ö.
Published: March 2006

Purpose: To compare three methods for standardizing volume rendering technique (VRT) protocols by studying aortic diameter measurements in magnetic resonance angiography (MRA) datasets.

Material and Methods: Datasets from 20 patients previously examined with gadolinium-enhanced MRA and with digital subtraction angiography (DSA) for abdominal aortic aneurysm were retrospectively evaluated by three independent readers. The MRA datasets were viewed using VRT with three different standardized transfer functions: the percentile method (Pc-VRT), the maximum-likelihood method (ML-VRT), and the partial range histogram method (PRH-VRT). The aortic diameters obtained with these three methods were compared with freely chosen VRT parameters (F-VRT) and with maximum intensity projection (MIP) concerning inter-reader variability and agreement with the reference method DSA.

Results: F-VRT parameters and PRH-VRT gave significantly higher diameter values than DSA, whereas Pc-VRT gave significantly lower values than DSA. The highest interobserver variability was found for F-VRT parameters and MIP, and the lowest for Pc-VRT and PRH-VRT. All standardized VRT methods were significantly superior to both MIP and F-VRT in this respect. The agreement with DSA was best for PRH-VRT, which was the only method with a mean error below 1 mm and which also had the narrowest limits of agreement (95% of cases between 2.1 mm below and 3.1 mm above DSA).

Conclusion: All the standardized VRT methods compare favorably with MIP and VRT with freely selected parameters as regards interobserver variability. The partial range histogram method, although systematically overestimating vessel diameters, gives results closest to those of DSA.
Magnetic resonance imaging findings of basal cell adenoma in curschmann-steinert myotonic dystrophy
Authors: Rudolph J. , Berl J. , Hamm B. , Klingebiel R.
Published: March 2006

Myotonic dystrophy Curschmann Steinert is a common hereditary disorder that in some cases can be combined with cutaneous tumors, which is an association that is rarely described in the literature. We present the magnetic resonance imaging in the unusual combination of a patient with known myotonic dystrophy and recurrent basal cell tumor.
Liver abscess associated with hepatic artery pseudoaneurysm with arteriovenous fistula: imaging and interventional management
Authors: Kang M. , Bapuraj J. R. , Khandelwal N. , Kochhar R. , Kalra N. , Verma G. R.
Published: March 2006

Hepatic artery pseudoaneurysm is an infrequently encountered entity that is usually seen secondary to trauma or surgical procedures. The clinical presentation is often due to complications such as massive intrahepatic or intraperitoneal bleeding as a result of rupture of the pseudoaneurysm into the biliary tree or peritoneal cavity, respectively. Hepatic artery pseudoaneurysm, associated with a liver abscess, has very rarely been described in the literature. We present the imaging features of a case of liver abscess associated with a hepatic artery pseudoaneurysm and complicated by rupture and formation of an arteriovenous fistula. The case was successfully managed by percutaneous endovascular embolization. The association between a hepatic artery pseudoaneurysm and a liver abscess must not be overlooked, bearing in mind the potentially fatal associated complications which can be averted or treated by timely intervention.
Effect of saline pushing after contrast material injection in abdominal multidetector computed tomography with the use of different iodine concentrations
Authors: Tatsugami F. , Matsuki M. , Kani H. , Tanikake M. , Miyao M. , Yoshikawa S. , Narabayashi I.
Published: March 2006

Purpose: To investigate whether saline pushing after contrast material improves hepatic vascular and parenchymal enhancement, and to determine whether this technique permits decreased contrast material concentration.

Material and Methods: 120 patients who underwent hepatic multidetector computed tomography were divided randomly into four groups (Groups A–D): receiving 100 ml of contrast material (300 mgI/ml) only (A) or with 50 ml of saline solution (B); or 100 ml of contrast material (350 mgI/ml) only (C) or with 50 ml of saline solution (D). Computed tomography (CT) values of the aorta in the arterial phase, the portal vein in the portal venous inflow phase, and the liver in the hepatic phase were measured. Visualization of the hepatic artery and the portal vein by 3D CT angiography was evaluated as well.

Results: Although the enhancement values of the aorta were not improved significantly with saline pushing, they continued at a high level to the latter slices with saline pushing. The enhancement value of the portal vein increased significantly and CT portography was improved with saline pushing. The enhancement value of the liver was not improved significantly using saline pushing. In a comparison between groups B and C, the enhancement values of the aorta and portal vein and the visualization of CT arteriography and portography were not statistically different.

Conclusion: The saline pushing technique can contribute to a decrease in contrast material concentration for 3D CT arteriography and portography.
Magnetic resonance renography findings and their clinical associations in nephropathia epidemica
Authors: Paakkala A. , Ryymin P. , Dastidar P. , Huhtala H. , Mustonen J.
Published: March 2006

Purpose: To evaluate, with magnetic resonance renography (MRR), the dynamics of renal function in patients with nephropathia epidemica (NE) and to correlate the findings with the clinical course of NE.

Material and Methods: MRR was performed on 20 hospitalized NE patients during the acute phase of the disease. A repeat MRR study was done 5–8 months later. Primary and repeat MRR studies were compared and functional findings evaluated.

Results: The uptake slope of the contrast enhancement curve was abnormal in the primary study in 14 patients, maximum level of enhancement in 11, decreasing slope of contrast enhancement curve in 14, and signal drop at time in 10 patients when the primary and repeat studies were compared. The greater change in the uptake slope of contrast enhancement, maximum level of enhancement, decreasing slope of enhancement, and signal drop at time between primary and repeat MRR studies evinced a mild association with the severity of clinical renal insufficiency and fluid volume overload.

Conclusion: Measurable functional MRR findings were recorded in 14/20 NE patients. The severity of the findings was mildly associated with the degree of clinical renal insufficiency and fluid volume overload.
Complete androgen insensitivity syndrome: report of a case with solitary pelvic kidney
Authors: Tokgoz H. , Turksoy O. , Boyacigil S. , Sakman B. , Yuksel E.
Published: March 2006

Complete androgen insensitivity syndrome, commonly known as the testicular feminization syndrome, is characterized by a 46, XY karyotype, bilateral testes, absent or hypoplastic Wolffian ducts, and female-appearing external genitalia with diminished axillary and pubic hair development. Although initial diagnosis in the child is difficult, the syndrome must be suspected after puberty if primary amenorrhea is present. Coexistence of genital defects with urologic abnormalities is expected in these cases because of close embryologic origin. However, unilateral renal agenesis with pelvic ectopia of the contralateral kidney does not seem so common. We report a case of testicular feminization syndrome with a solitary kidney located in bony pelvis on the left side.
Computed tomography features of spontaneously perforated pyometra: a case report
Authors: Chan K-S. , Tan C-K. , Mak C-W. , Chia C-C. , Kuo C-Y. , Yu W-L.
Published: March 2006

Spontaneous perforation of pyometra is an extremely rare emergent gynecologic disease. We report a 73-year-old woman with a spontaneously perforated pyometra presenting with acute abdomen in the emergency department. A dedicated computed tomography examination of the abdominal and pelvic regions revealed the diagnosis. The patient recovered well after surgical intervention and antibiotic treatment.
Identifying Opportunity for Conflict: Politically Active Dyads
Authors: Quackenbush Stephen L.
Published: March 2006

Since states cannot fight without the opportunity to do so, empirical identification of opportunity is important. Unfortunately, previous measures of opportunity—politically relevant dyads, the politically relevant international environment, and regional dyads—are inadequate. I attempt to measure opportunity by developing the concept of a politically active dyad, using contiguity, power status, and alliances as defining characteristics. I then use Braumoeller and Goertz's (2000) methodology for necessary conditions to compare active dyads with previous measures. This test demonstrates that although previous measures are unable to capture opportunity as a necessary condition for international conflict, the concept of politically active dyads does.
Leaders' Motivations and Actions: Explaining Government-Dissident Conflict-Cooperation Processes
Authors: Shellman Stephen M.
Published: March 2006

This study posits a theory to explain government and dissident sequential responses to one another and develops a statistical model to test the implied hypotheses. While competing hypotheses emerge from both formal and empirical models, the current literature lacks a single, coherent, theoretical, and empirically corroborated model of the interactive relationship between dissident and government behavior. The study seeks to fill this lacuna in the literature by developing a comprehensive theory to account for a large number of competing hypotheses within a single framework. The subsequent empirical tests enable one to find support for the various competing hypotheses under different sets of conditions. The analyses of Chile (1983—1992) and Venezuela (1987— 1992) provide evidence that the model captures well the sequential responses of Chilean and Venezuelan governments and dissidents.
Compliance with the Laws of War: Dataset and Coding Rules
Authors: Morrow James D. , Jo Hyeran
Published: March 2006

This report describes a dataset on compliance with the laws of war in 20th century interstate wars. We introduce the dataset, discuss sources, and explain the coding schemes. The unit is a directed warring dyad in a given war for one of nine issues. We collect five dimensions of compliance, including quality of the data, and construct a single measure of compliance. Reciprocity exists in the data, and treaty law strengthens reciprocity by clarifying what acts constitute violations. Compliance varies across issues, matching the scope for individual violations. States are more likely to respond reciprocally to violations by individuals than to those that are state policy.
Gene Expression Dose-Response of Liver with a Genotoxic and Nongenotoxic Carcinogen
Authors: Seidel Shawn D. , Stott William T. , Kan H. Lynn , Sparrow Barney R. , Gollapudi B. Bhaskar
Published: March 2006

Tumorigenic mechanisms due to chemical exposure are broadly classified as either genotoxic or nongenotoxic. Genotoxic mechanisms are generally well defined; however nongenotoxic modes of tumorgenesis are less straightforward. This study was undertaken to help elucidate dose-response changes in gene expression (transcriptome) in the liver of rats in response to administration of known genotoxic or nongenotoxic liver carcinogens. Male Big Blue Fischer 344 rats were treated for 28-days with 0, 0.1, 0.3, 1.0, or 3.0 mg/kg/day of the genotoxin 2-acetylaminofluorene (AAF) or 0, 10, 30, 60, or 100 mg/kg/day of the nongenotoxin phenobarbital (PB). Transcriptome analysis was performed using the relatively focused Clontech Rat Toxicology II microarray (465 genes) and hybridized with 32P-labeled cDNA target. The analysis indicated that after 28 days of treatment, AAF altered the expression of 14 genes (9 up-and 5 down-regulated) and PB altered the expression of 18 genes (10 up- and 8 down-regulated). Of the limited genes whose expression was altered by AAF and PB, four were altered in common, two up-regulated, and two down-regulated. Several of the genes that show modulation of transcriptional activity following AAF and PB treatment display an atypical dose-response relationship such that the expression at the higher doses tended to be similar to that of control. This high-dose effect could potentially be caused by adaptation, toxicity, or tissue remodeling. These results suggest that the transcriptional response of the cells to higher doses of a toxic agent is likely to be different from that of a low-dose exposure.
The existence of quasimeromorphic mappings in dimension 3
Authors: Saucan Emil
Published: March 2006

We prove that a Kleinian group

G
G

acting on

H

3

\mathbb {H}^{3}

admits a non-constant

G
G

-automorphic function, even if it has torsion elements, provided that the orders of the elliptic elements are uniformly bounded. This is accomplished by developing a method for meshing distinct fat triangulations which is fatness preserving. We further show how to adapt the proof to higher dimensions.
Specific functional interactions of nucleotides at key -3 and +4 positions flanking the initiation codon with components of the mammalian 48S translation initiation complex
Authors: Pisarev Andrey V. , Kolupaeva Victoria G. , Pisareva Vera P. , Merrick William C. , Hellen Christopher U.T. , Pestova Tatyana V.
Published: March 2006

Eukaryotic initiation factor (eIF) 1 maintains the fidelity of initiation codon selection and enables mammalian 43S preinitiation complexes to discriminate against AUG codons with a context that deviates from the optimum sequence GCC(A/G)CCAUGG, in which the purines at -3 and +4 positions are most important. We hypothesize that eIF1 acts by antagonizing conformational changes that occur in ribosomal complexes upon codon-anticodon base-pairing during 48S initiation complex formation, and that the role of -3 and +4 context nucleotides is to stabilize these changes by interacting with components of this complex. Here we report that U and G at +4 both UV-cross-linked to ribosomal protein (rp) S15 in 48S complexes. However, whereas U cross-linked strongly to C1696 and less well to AA1818-1819 in helix 44 of 18S rRNA, G cross-linked exclusively to AA1818-1819. U at -3 cross-linked to rpS5 and eIF2α, whereas G cross-linked only to eIF2α. Results of UV cross-linking experiments and of assays of 48S complex formation done using α-subunit-deficient eIF2 indicate that eIF2α's interaction with the -3 purine is responsible for recognition of the -3 context position by 43S complexes and suggest that the +4 purine/AA1818-1819 interaction might be responsible for recognizing the +4 position.
Cdc42 controls progenitor cell differentiation and β-catenin turnover in skin
Authors: Wu Xunwei , Quondamatteo Fabio , Lefever Tine , Czuchra Aleksandra , Meyer Hannelore , Chrostek Anna , Paus Ralf , Langbein Lutz , Brakebusch Cord
Published: March 2006

Differentiation of skin stem cells into hair follicles (HFs) requires the inhibition of β-catenin degradation, which is controlled by a complex containing axin and the protein kinase GSK3β. Using conditional gene targeting in mice, we show now that the small GTPase Cdc42 is crucial for differentiation of skin progenitor cells into HF lineage and that it regulates the turnover of β-catenin. In the absence of Cdc42, degradation of β-catenin was increased corresponding to a decreased phosphorylation of GSK3β at Ser 9 and an increased phosphorylation of axin, which is known to be required for binding of β-catenin to the degradation machinery. Cdc42-mediated regulation of β-catenin turnover was completely dependent on PKCζ, which associated with Cdc42, Par6, and Par3. These data suggest that Cdc42 regulation of β-catenin turnover is important for terminal differentiation of HF progenitor cells in vivo.
Characterization of the metabolic phenotypes of Cushing's syndrome and growth hormone deficiency: a study of body composition and energy metabolism
Authors: Burt Morton G. , Gibney James , Ho Ken K. Y.
Published: March 2006

Objective  A comparison of the severity and distribution of perturbations in body composition and their relationship to energy metabolism in glucocorticoid excess and GH deficiency (GHD) has not been undertaken before. The aim of this study was to investigate the impact of Cushing's syndrome (CS) and GHD on whole and regional body composition and energy metabolism.

Design  Cross‐sectional study design.

Patients  Eighteen subjects with CS (12 women, aged = 41·5 ± 3·0 years, 24‐h urinary free cortisol = 1601 ± 361 nmol/day, normal < 300 nmol/day), 22 subjects with GHD (14 women, age = 42·9 ± 2·9 years) and 18 normal subjects (11 women, age = 46·8 ± 2·8 years).

Measurements  Lean body mass (LBM), fat mass (FM) and regional body composition were assessed by dual‐energy X‐ray absorptiometry (DEXA). Resting energy expenditure (REE) and fat oxidation (Fox) were assessed by indirect calorimetry.

Results  Mean percentage FM was significantly greater by 30% in CS (P = 0·002) and 22% in GH‐deficient subjects (P = 0·014) than in normal subjects. LBM was significantly lower by 15% in CS (P = 0·002) and 11% in GHD (P = 0·013). In CS, the proportion of lean tissue in the limbs was 12% less than in normal (P = 0·001) and GH‐deficient subjects (P = 0·0005). Truncal fat represented a greater proportion of total FM in CS (52·5 ± 1·8%vs. 46·9 ± 1·3%, P = 0·014) than in normal subjects, but not in GHD. REE and Fox, corrected for LBM, were significantly lower in GHD (P < 0·02 for both vs. normal) but not in CS.

Conclusion  FM was higher and LBM lower in both CS and GHD. However, there is a greater abnormality of regional body composition in patients with CS who exhibit a lower limb lean mass and a greater truncal fat. Reduced REE and Fox contribute to increased adiposity in GHD. As REE and Fox are not perturbed in CS, other mechanisms must explain the marked gain in truncal and total fat.