bluuebunny/crossref_metadata_2025 huggingface dataset:
High‐resolution MRS in the presence of field inhomogeneity via intermolecular double‐quantum coherences on a 3‐T whole‐body scanner
Authors: Lin Yanqin , Gu Tianliang , Chen Zhong , Kennedy Scott , Jacob Mathews , Zhong Jianhui
Published: January 2010

Signals from intermolecular double‐quantum coherences (iDQCs) have been shown to be insensitive to macroscopic field inhomogeneities and thus enable acquisition of high‐ resolution MR spectroscopy in the presence of large inhomogeneous fields. In this paper, localized iDQC 1H spectroscopy on a whole‐body 3‐T MR scanner is reported. Experiments with a brain metabolite phantom were performed to quantify characteristics of the iDQC signal under different conditions. The feasibility of in vivo iDQC high‐resolution MR spectroscopy in the presence of large intrinsic and external field inhomogeneity (in the order of hundreds of hertz) was demonstrated in the whole cerebellum of normal volunteers in a scan time of about 6.5 min. Major metabolite peaks were well resolved in the reconstructed one‐dimensional spectra projected from two‐dimensional iDQC acquisitions. Investigations on metabolite ratios, signal‐to‐noise ratio, and line width were performed and compared with results obtained with conventional point‐resolved spectroscopy/MR spectroscopy in homogeneous fields. Metabolite ratios from iDQC results showed excellent consistency under different in vitro and in vivo conditions, and they were similar to those from point‐resolved spectroscopy with small voxel sizes in homogeneous fields. MR spectroscopy with iDQCs can be applied potentially for quantification of gross metabolite changes due to diseases in large brain volumes with high field inhomogeneity. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Hyperpolarized 13C spectroscopy and an NMR‐compatible bioreactor system for the investigation of real‐time cellular metabolism
Authors: Keshari Kayvan R. , Kurhanewicz John , Jeffries Rex E. , Wilson David M. , Dewar Brian J. , Van Criekinge Mark , Zierhut Matthew , Vigneron Daniel B. , Macdonald Jeffrey M.
Published: January 2010

The purpose of this study was to combine a three‐dimensional NMR‐compatible bioreactor with hyperpolarized 13C NMR spectroscopy in order to probe cellular metabolism in real time. JM1 (immortalized rat hepatoma) cells were cultured in a three‐dimensional NMR‐compatible fluidized bioreactor. 31P spectra were acquired before and after each injection of hyperpolarized [1‐13C] pyruvate and subsequent 13C spectroscopy at 11.7 T. 1H and two‐dimensional 1H‐1H‐total correlation spectroscopy spectra were acquired from extracts of cells grown in uniformly labeled 13C‐glucose, on a 16.4 T, to determine 13C fractional enrichment and distribution of 13C label. JM1 cells were found to have a high rate of aerobic glycolysis in both two‐dimensional culture and in the bioreactor, with 85% of the 13C label from uniformly labeled 13C‐glucose being present as either lactate or alanine after 23 h. Flux measurements of pyruvate through lactate dehydrogenase and alanine aminotransferase in the bioreactor system were 12.18 ± 0.49 nmols/sec/108 cells and 2.39 ± 0.30 nmols/sec/108 cells, respectively, were reproducible in the same bioreactor, and were not significantly different over the course of 2 days. Although this preliminary study involved immortalized cells, this combination of technologies can be extended to the real‐time metabolic exploration of primary benign and cancerous cells and tissues prior to and after therapy. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Slow magic‐angle coil spinning: A high‐sensitivity and high‐resolution NMR strategy for microscopic biological specimens
Authors: Wong Alan , Aguiar Pedro M. , Sakellariou Dimitris
Published: January 2010

High‐resolution magic‐angle spinning has become a valuable tool to study biologic samples; however, there are only a few high‐resolution magic‐angle spinning methodologies that have been explored specifically to deal with small semisolid biomaterials such as tissues. Here, we report a novel high‐resolution 1H NMR spectroscopic approach using magic‐angle coil spinning. We demonstrate its potential for intact tissues by combining a resonant microcoil with a large‐volume commercial magic‐angle spinning rotor, where the microcoil offers incredible sensitivity and the large‐volume magic‐angle spinning rotor provides stable slow magic‐angle spinning. This approach provides high‐resolution spectra with high sensitivity and the preservation of living biologic specimens for an accurate chemical analysis. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Simultaneous B0‐ and B1+‐Map acquisition for fast localized shim, frequency, and RF power determination in the heart at 3 T
Authors: Schär Michael , Vonken Evert‐Jan , Stuber Matthias
Published: January 2010

High‐field (≥3 T) cardiac MRI is challenged by inhomogeneities of both the static magnetic field (B0) and the transmit radiofrequency field (B1+). The inhomogeneous B fields not only demand improved shimming methods but also impede the correct determination of the zero‐order terms, i.e., the local resonance frequency f0 and the radiofrequency power to generate the intended local B1+ field. In this work, dual echo time B0‐map and dual flip angle B1+‐map acquisition methods are combined to acquire multislice B0‐ and B1+‐maps simultaneously covering the entire heart in a single breath hold of 18 heartbeats. A previously proposed excitation pulse shape dependent slice profile correction is tested and applied to reduce systematic errors of the multislice B1+‐map. Localized higher‐order shim correction values including the zero‐order terms for frequency f0 and radiofrequency power can be determined based on the acquired B0‐ and B1+‐maps. This method has been tested in 7 healthy adult human subjects at 3 T and improved the B0 field homogeneity (standard deviation) from 60 Hz to 35 Hz and the average B1+ field from 77% to 100% of the desired B1+ field when compared to more commonly used preparation methods. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
A simulation‐based analysis of the potential of compressed sensing for accelerating passive mr catheter visualization in endovascular therapy
Authors: Yerly Jérôme , Lauzon M. Louis , Chen Henry S. , Frayne Richard
Published: January 2010

Passive MRI is a promising approach to visualize catheters in guiding and monitoring endovascular intervention and may offer several clinical advantages over the current x‐ray fluoroscopy “gold standard.” Endovascular MRI has limitations, however, such as difficulty in visualizing catheters and insufficient temporal resolution. The multicycle projection dephaser method is a background signal suppression technique that improves the conspicuity of passive catheters by generating a sparse (i.e., catheter only) image. One approach to improve the temporal resolution is to undersample the k‐space and then apply nonlinear methods, such as compressed sensing, to reconstruct the MR images. This feasibility study investigates the potential synergies between multicycle projection dephaser and compressed sensing reconstruction for real‐time passive catheter tracking. The multicycle projection dephaser method efficiently suppressed the background signal, and compressed sensing allowed MR images to be reconstructed with superior catheter conspicuity and spatial resolution when compared to the more conventional zero‐filling reconstruction approach. Moreover, compressed sensing allowed the shortening of total acquisition time (by up to 32 times) by vastly undersampling the k‐space while simultaneously preserving spatial resolution and catheter conspicuity. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Parametric dependence of myocardial blood oxygen level dependent, balanced steady‐state free‐precession imaging at 1.5 T: Theory and experiments
Authors: Zhou Xiangzhi , Tang Richard , Klein Rachel , Li Debiao , Dharmakumar Rohan
Published: January 2010

Myocardial blood oxygen level dependent, balanced steady‐state free precession (bSSFP) imaging is a relatively new technique for evaluating myocardial oxygenation changes in the presence of coronary artery stenosis. However, the dependence of myocardial bSSFP blood oxygen level dependent signal on imaging parameters has not been well studied. In this work, modeling capillaries as cylinders that act as magnetic perturbers, the Monte Carlo method was used to simulate spin relaxation via diffusion in a field variation inside and outside blood vessels. bSSFP signal changes at various levels of capillary blood oxygen saturation, for a range of pulse repetition times, flip angle, capillary blood volume fraction, vessel wall permeability, water diffusion coefficient, vessel angle to static magnetic field, and the impact of bulk frequency shifts were studied. The theoretical dependence of bSSFP blood oxygen level dependent contrast on pulse repetition times and flip angle was confirmed by experiments in an animal model with controllable coronary stenosis. Results showed that, with the standard bSSFP acquisition, optimum bSSFP blood oxygen level dependent contrast could be obtained at pulse repetition times = 6.0 ms and flip angle = 70°. Additional technical improvements that preserve the image quality may be necessary to further increase the myocardial bSSFP blood oxygen level dependent sensitivity at 1.5 T through even longer pulse repetition times. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Positive contrast with alternating repetition time SSFP (PARTS): A fast imaging technique for SPIO‐labeled cells
Authors: Çukur Tolga , Yamada Mayumi , Overall William R. , Yang Phillip , Nishimura Dwight G.
Published: January 2010

There has been recent interest in positive‐contrast MRI methods for noninvasive tracking of cells labeled with superparamagnetic iron‐oxide nanoparticles. Low‐tip‐angle balanced steady‐state free precession sequences have been used for fast, high‐resolution, and flow‐insensitive positive‐contrast imaging; however, the contrast can be compromised by the limited suppression of the on‐resonant and fat signals. In this work, a new technique that produces positive contrast with alternating repetition time steady‐state free precession is proposed to achieve robust background suppression for a broad range of tissue parameters. In vitro and in vivo experiments demonstrate the reliability of the generated positive contrast. The results indicate that the proposed method can enhance the suppression level by up to 18 dB compared with conventional balanced steady‐state free precession. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Asymmetries of the balanced SSFP profile. Part II: White matter
Authors: Miller Karla L. , Smith Stephen M. , Jezzard Peter
Published: January 2010

The signal profile measured in balanced steady‐state free precession has been shown to exhibit tissue‐dependent asymmetries that were hypothesized to relate to properties of the tissue microenvironment. It was proposed that balanced steady‐state free precession asymmetry may reflect subtle features of the frequency distribution in tissue. The present work investigates the large balanced steady‐state free precession asymmetries observed in white matter. First, maps quantifying the asymmetry are presented, which demonstrate considerable heterogeneity within white matter, with some tracts exhibiting significant asymmetry and others having a nearly symmetric profile. These maps are compared with a diffusion‐tensor atlas and indicate that the highest asymmetry is found in tracts oriented perpendicular to the main magnetic field. Measurements conducted at multiple repetition times suggest that the asymmetries are characterized by relatively small frequency shifts. These results are discussed in the context of previous work studying gradient‐recalled echo (GRE) signal behavior in white matter, and it is suggested that these two techniques are detecting closely related phenomena. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Non‐contrast‐enhanced pulmonary vein MRI with a spatially selective slab inversion preparation sequence
Authors: Hu Peng , Chuang Michael L. , Kissinger Kraig V. , Goddu Beth , Goepfert Lois A. , Rofsky Neil M. , Manning Warren J. , Nezafat Reza
Published: January 2010

We propose a non‐contrast‐enhanced, three‐dimensional, free‐breathing, electrocardiogram‐gated, gradient recalled echo sequence with a slab‐selective inversion for pulmonary vein (PV) MRI. A sagittal inversion slab was applied prior to data acquisition to suppress structures adjacent to the left atrium (LA) and PVs, thereby improving the conspicuity of the PV and LA. Compared with other MR angiography methods using an inversion pulse, the proposed method does not require signal subtraction and the inversion slab is not parallel to the imaging slab. The feasibility of the proposed method was demonstrated in healthy subjects. The inversion slab thickness and inversion time were optimized to be 60 mm and 500 ms, respectively. Compared to conventional gradient recalled echo imaging without inversion, the proposed technique significantly increased the contrast‐to‐noise ratios between the LA and the right atrium by 20‐fold (P < 0.01), increased the contrast‐to‐noise ratios between the PVs and right atrium by 10‐fold (P < 0.03), and increased the contrast‐to‐noise ratios between the PVs, LA and pulmonary artery by 4‐fold (P < 0.01 for both). The signal‐to‐noise ratios of the PVs and the LA were similar with and without the inversion slab (P > 0.3). The proposed technique greatly enhances the conspicuity of the PVs and LA without significant loss of signal‐to‐noise ratio. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Design and use of variable flip angle schedules in transient balanced SSFP subtractive imaging
Authors: Smith Travis , Zun Zungho , Wong Eric C. , Nayak Krishna S.
Published: January 2010

In subtractive imaging modalities, the differential longitudinal magnetization decays with time, necessitating signal‐efficient scanning methods. Balanced steady‐state free precession pulse sequences offer greater signal strength than conventional spoiled gradient echo sequences, even during the transient approach to steady state. Although traditional balanced steady‐state free precession requires that each excitation pulse use the same flip angle, operating in the transient regimen permits the application of variable flip angle schedules that can be tailored to optimize certain signal characteristics. A computationally efficient technique is presented to generate variable flip angle schedules efficiently for any optimization metric. The validity of the technique is shown using two phantoms, and its potential is demonstrated in vivo with a variable angle schedule to increase the signal‐to‐noise ratio (SNR) in myocardial tissue. Using variable flip angles, the mean SNR improvement in subtractive imaging of myocardial tissue was 18.2% compared to conventional, constant flip angle, balanced steady‐state free precession (P = 0.0078). Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Dual inversion recovery, ultrashort echo time (DIR UTE) imaging: Creating high contrast for short‐T2 species
Authors: Du Jiang , Takahashi Atsushi M. , Bae Won C. , Chung Christine B. , Bydder Graeme M.
Published: January 2010

Imaging of short‐T2 species requires not only a short echo time but also efficient suppression of long‐T2 species in order to maximize the short‐T2 contrast and dynamic range. This paper introduces a method of long‐T2 suppression using two long adiabatic inversion pulses. The first adiabatic inversion pulse inverts the magnetization of long‐T2 water and the second one inverts that of fat. Short‐T2 species experience a significant transverse relaxation during the long adiabatic inversion process and are minimally affected by the inversion pulses. Data acquisition with a short echo time of 8 μs starts following a time delay of inversion time (TI1) for the inverted water magnetization to reach a null point and a time delay of TI2 for the inverted fat magnetization to reach a null point. The suppression of long‐T2 species depends on proper combination of TI1, TI2, and pulse repetition time. It is insensitive to radiofrequency inhomogeneities because of the adiabatic inversion pulses. The feasibility of this dual inversion recovery ultrashort echo time technique was demonstrated on phantoms, cadaveric specimens, and healthy volunteers, using a clinical 3‐T scanner. High image contrast was achieved for the deep radial and calcified layers of articular cartilage, cortical bone, and the Achilles tendon. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
MRI and localized proton spectroscopy in human leg muscle at 7 tesla using longitudinal traveling waves
Authors: Webb Andrew G. , Collins Christopher M. , Versluis Maarten J. , Kan Hermien E. , Smith Nadine B.
Published: January 2010

Using a small resonant loop to produce a longitudinal traveling wave on a human 7‐T system allows MR to be performed over the entire volume of the human leg. We have used this capability to perform localized proton MR spectroscopy of the lipid composition of muscle in volunteers with a coil placed ∼30 cm away from the region of interest. Spectra with a reasonable signal‐to‐noise ratio can be acquired in a clinically relevant data acquisition time of less than 5 min using the loop in transmit/receive mode, maintaining the full flexibility to acquire spectra from any part of the calf and/or thigh. If a local receive coil is used in combination with the remote transmit coil, then the signal‐to‐noise improves significantly, as expected. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Relationship between brain R2 and liver and serum Iron concentrations in elderly men
Authors: House Michael J. , St. Pierre Timothy G. , Milward Elizabeth A. , Bruce David G. , Olynyk John K.
Published: January 2010

Studies of iron overload in humans and animals suggest that brain iron concentrations may be related in a regionally specific way to body iron status. However, few quantitative studies have investigated the associations between peripheral and regional brain iron in a normal elderly cohort. To examine these relationships, we used MRI to measure the proton transverse relaxation rate (R2) in 13 gray and white matter brain regions in 18 elderly men (average age, 75.5 years) with normal cognition. Brain R2 values were compared with liver iron concentrations measured using the FerriScan® MRI technique and serum iron indices. R2 values in high‐iron gray matter regions were significantly correlated (positively) with liver iron concentrations (globus pallidus, ventral pallidum) and serum transferrin saturation (caudate nucleus, globus pallidus, putamen) measured concurrently with brain R2, and with serum iron concentrations (caudate nucleus, globus pallidus) measured three years before the current study. Our results suggest that iron levels in specific gray matter brain regions are influenced by systemic iron status in elderly men. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Design and evaluation of a 32‐channel phased‐array coil for lung imaging with hyperpolarized 3‐helium
Authors: Meise Florian M. , Rivoire Julien , Terekhov Maxim , Wiggins Graham C. , Keil Boris , Karpuk Sergej , Salhi Zahir , Wald Lawrence L. , Schreiber Laura M.
Published: January 2010

Imaging with hyperpolarized 3‐helium is becoming an increasingly important technique for MRI diagnostics of the lung but is hampered by long breath holds (>20 sec), which are not always applicable in patients with severe lung disease like chronic obstructive pulmonary disease (COPD) or α‐1‐anti‐trypsin deficiency. Additionally, oxygen‐induced depolarization decay during the long breath holds complicates interpretation of functional data such as apparent diffusion coefficients. To address these issues, we describe and validate a 1.5‐T, 32‐channel array coil for accelerated 3He lung imaging and demonstrate its ability to speed up imaging 3He. A signal‐to‐noise ratio increase of up to a factor of 17 was observed compared to a conventional double‐resonant birdcage for unaccelerated imaging, potentially allowing increased image resolution or decreased gas production requirements. Accelerated imaging of the whole lung with one‐dimensional and two‐dimensional acceleration factors of 4 and 4 × 2, respectively, was achieved while still retaining excellent image quality. Finally, the potential of highly parallel detection in lung imaging is demonstrated with high‐resolution morphologic and functional images. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Dual half‐echo phase correction for implementation of 3D radial SSFP at 3.0 T
Authors: Klaers Jessica , Jashnani Yogesh , Jung Youngkyoo , Brodsky Ethan , Jacobson Joshua , Kijowski Richard , Block Walter F.
Published: January 2010

Fat/water separation methods such as fluctuating equilibrium magnetic resonance and linear combination steady‐state free precession have not yet been successfully implemented at 3.0 T due to extreme limitations on the time available for spatial encoding with the increase in magnetic field strength. We present a method to utilize a three‐dimensional radial sequence combined with linear combination steady‐state free precession at 3.0 T to take advantage of the increased signal levels over 1.5 T and demonstrate high spatial resolution compared to Cartesian techniques. We exploit information from the two half‐echoes within each pulse repetition time to correct the accumulated phase on a point‐by‐point basis, thereby fully aligning the phase of both half‐echoes. The correction provides reduced sensitivity to static field (B0) inhomogeneity and robust fat/water separation. Resultant images in the knee joint demonstrate the necessity of such a correction, as well as the increased isotropic spatial resolution attainable at 3.0 T. Results of a clinical study comparing this sequence to conventional joint imaging sequences are included. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.
Time discontinuous Galerkin methods with energy decaying correction for non‐linear elastodynamics
Authors: de Miranda Stefano , Mancuso Massimo , Ubertini Francesco
Published: January 2010

In this paper a new time discontinuous Galerkin (TDG) formulation for non‐linear elastodynamics is presented. The new formulation embeds an energy correction which ensures truly energy decaying, thus allowing to achieve unconditional stability that, as shown in the paper, is not guaranteed by the classical TDG formulation. The resulting method is simple and easily implementable into existing finite element codes. Moreover, it inherits the desirable higher‐order accuracy and high‐frequency dissipation properties of the classical formulation. Numerical results illustrate the very good performance of the proposed formulation. Copyright © 2010 John Wiley & Sons, Ltd.
Evaluation of the Met Office global forecast model using Geostationary Earth Radiation Budget (GERB) data
Authors: Allan Richard P. , Slingo Anthony , Milton Sean F. , Brooks Malcolm E.
Published: January 2010

Simulations of the top‐of‐atmosphere radiative‐energy budget from the Met Office global numerical weather‐prediction model are evaluated using new data from the Geostationary Earth Radiation Budget (GERB) instrument on board the Meteosat‐8 satellite. Systematic discrepancies between the model simulations and GERB measurements greater than 20 Wm−2in outgoing long‐wave radiation (OLR) and greater than 60 Wm−2in reflected short‐wave radiation (RSR) are identified over the period April–September 2006 using 12 UTC data. Convective cloud over equatorial Africa is spatially less organized and less reflective than in the GERB data. This bias depends strongly on convective‐cloud cover, which is highly sensitive to changes in the model convective parametrization. Underestimates in model OLR over the Gulf of Guinea coincide with unrealistic southerly cloud outflow from convective centres to the north. Large overestimates in model RSR over the subtropical ocean, greater than 50 Wm−2at 12 UTC, are explained by unrealistic radiative properties of low‐level cloud relating to overestimation of cloud liquid water compared with independent satellite measurements. The results of this analysis contribute to the development and improvement of parametrizations in the global forecast model. Copyright © 2007 Royal Meteorological Society
A three‐dimensional mountain wave imaged in satellite radiance throughout the stratosphere: Evidence of the effects of directional wind shear
Authors: Eckermann Stephen D. , Ma Jun , Wu Dong L. , Broutman Dave
Published: January 2010

Swath‐scanned thermal radiances from the Advanced Microwave Sounding Units (AMSU‐A) on the NOAA and Aqua satellites are used to image the horizontal temperature structure of a long‐wavelength mountain wave that formed over southern Scandinavia on 14 January 2003. Data from all six stratospheric channels show this wave propagating through the full depth of the stratosphere. In channels 9–11 (altitudes ∼20–90 hPa) the imaged wave has a phase structure broadly consistent with a stationary wave radiated by the southeastward flow over and above the quasi‐elliptical terrain of southern Norway. Channel 12 radiances at ∼10 hPa, however, show a remarkable abrupt change in imaged wave structure: the horizontal wavelength contracts, phase lines rotate anticlockwise by 30° –40° , and peak activity migrates to the south to lie over Denmark and northern Germany. Similar structure persists in channels 13 and 14 (at ∼2–5 hPa) with progessively increasing radiance amplitudes. These features are stable over the ∼10 hours of AMSU‐A measurements from five separate overpasses, and are validated against independent radiances acquired by the Atmospheric Infrared Sounder (AIRS) and retrieved AIRS/AMSU‐A temperature profiles from the Aqua overpass.

This change at the channel 11/12 interface coincides with an onset of anticlockwise rotation (backing) and intensification of background stratospheric winds with height. Fourier‐ray and spatial ray modelling incorporating these directionally sheared winds and simplified orographic forcing reproduce the salient features of the observations, but only after wave‐induced temperature perturbations have been converted to channel radiances using a forward model. The differential visibility of various components of this three‐dimensional mountain wave to the AMSU‐A channel weighting functions has a first‐order impact on the observations at heights above 10 hPa. Once that is factored in, the combined observations and modelling provide direct experimental support for the Shutts model's predictions of how backing wind vectors affect the vertical evolution of three‐dimensional mountain waves. Implications of these observations for orographic gravity wave drag parametrization are briefly discussed. Copyright © 2007 Royal Meteorological Society
DNA Damage-Induced Degradation of Cdc25A Does Not Lead to Inhibition of Cdk2 Activity in Mouse Embryonic Stem Cells
Authors: Koledova Zuzana , Kafkova Leona Raskova , Krämer Alwin , Divoky Vladimir
Published: January 2010

Cyclin-dependent kinase two (Cdk2) is the major regulator of the G1/S transition and the target of an activated G1 checkpoint in somatic cells. In the presence of DNA damage, Cdk2 kinase activity is abrogated by a deficiency of Cdc25A phosphatase, which is marked by Chk1/Chk2 for proteasomal degradation. Embryonic stem cells (ESCs) lack a G1 checkpoint response. In this study, we analyzed the G1 checkpoint pathways in mouse ESCs (mESCs) in the presence of DNA double-strand breaks evoked by ionizing radiation (IR). We show that checkpoint pathways, which operate during G1 phase in somatic cells, are activated in mESCs after IR; however, Cdk2 activity is not abolished. We demonstrate that Cdc25A is degraded in mESCs, but this degradation is not regulated by Chk1 and Chk2 kinases because they are sequestered to the centrosome. Instead, Cdc25A degradation is governed by glycogen synthase kinase-3β kinase. We hypothesize that Cdc25A degradation does not inhibit Cdk2 activity because a considerable proportion of Cdk2 molecules localize to the cytoplasm and centrosomes in mESCs, where they may be sheltered from regulation by nuclear Cdc25A. Finally, we show that a high Cdk2 activity, which is irresponsive to DNA damage, is the driving force of the rapid escape of mESCs from G1 phase after DNA damage.
Formal, theoretical aspects of systems engineering
Authors: Simpson Mary J. , Simpson Joseph J.
Published: January 2010

In “Principles of Complex Systems for Systems Engineering,” S.A. Sheard and A. Mostashari [Syst Eng 12 (2009), 295–311] suggest issues related to a formal and theoretical background to systems engineering as well as the definition and analysis of complex systems (p. 295): “Systems engineering (SE) has evolved without much of a formal or theoretical background for its practices; instead it has relied on experientially developed principles and heuristics [Defoe, 1993; Rechtin, 1991; Stevens et al., 1998].” This communication outlines some of the existing formal, theoretical systems engineering literature, discusses the provided definition of complex systems, examines “Ordered Systems Engineering” in the context of existing systems engineering literature, and reflects on the principles of complex systems for systems engineering. © 2010 Wiley Periodicals, Inc. Syst Eng
Nerve Growth Factor‐β Expression Is Associated with Lymph Node Metastasis and Nerve Infiltration in Human Hilar Cholangiocarcinoma
Authors: Xu Lei‐bo , Liu Chao , Gao Guo‐quan , Yu Xian‐huan , Zhang Rui , Wang Jie
Published: January 2010

Background

Angiogenesis and lymphangiogenesis are important processes in the progression of malignant tumors. Previous studies have shown that nerve growth factor‐β (NGF‐β) can promote the initiation and progression of many tumors. In addition, vascular endothelial growth factor‐C (VEGF‐C) has become recognized as the most important lymphangiogenic factor. In the present study, the expression of NGF‐β in human hilar cholangiocarcinoma and its relationship with lymphangiogenesis, lymph node metastasis, nerve infiltration, and VEGF‐C expression was investigated.

Methods

Nerve growth factor‐β and VEGF‐C expression were investigated by immunohistochemistry in samples from 28 cases of hilar cholangiocarcinoma. The lymphatic vessel density (LVD) in the tumor tissue that indicated lymphangiogenesis were calculated by immunostaining with the lymphendothelial‐specific antibody D2‐40. The relationship between NGF‐β expression and VEGF‐C expression, lymphangiogenesis, lymph node metastasis, and nerve infiltration was evaluated.

Results

The overexpression of NGF‐β and VEGF‐C occurred in 57.1% (16/28) and 46.4% (13/28) of tumor samples, respectively. Nerve growth factor‐β overexpression was highly correlated with VEGF‐C overexpression (P = 0.005), LVD (P < 0.001), lymph node metastasis (P = 0.021), nerve infiltration (P = 0.019), and tumor stage (P = 0.040). Furthermore, VEGF‐C overexpression was highly correlated with LVD (P < 0.001) and lymph node metastasis (P < 0.001). However, there was no statistic significance in the relation between NGF‐β expression and sex (P = 0.185), age (P = 0.387), maximal tumor size (P = 0.736), Bismuth classification (P = 0.627) as well as histological grade (P = 0.203).

Conclusions

Nerve growth factor‐β might promote lymph node metastasis and nerve infiltration in human hilar cholangiocarcinoma.
Parental Decisions Regarding a Prenatally Detected Fetal Chromosomal Abnormality and the Impact of Genetic Counseling: An Analysis of 38 Cases with Aneuploidy in Southeast Turkey
Authors: Balkan Mahmut , Kalkanli Sevgi , Akbas Halit , Yalinkaya Ahmet , Alp M. Nail , Budak Turgay
Published: January 2010

This study investigated parental decision‐making to terminate or continue a pregnancy after prenatal diagnosis of a chromosomal abnormality among a sample of patients in Southeast Turkey. Between 2004 and 2007, 1068 amniocentesis tests were performed in the Medical Biology and Genetic Department Laboratory at Dicle University. Aneuploidy was found in 38 cases (3.56%). Genetic counseling was provided for the couples that received abnormal results, and they were later interviewed and asked if they had continued or interrupted the pregnancy after the diagnosis. When confronted with autosomal aneuploidy in which a severe prognosis was expected, 85% of cases decided to terminate the pregnancy. When confronted with sex chromosome aneuploidy with a low risk of an abnormal clinical phenotype 60% of cases decided to continue the pregnancy. Among the diagnoses with aneuploidy, pregnancy was continued in 21.1% of cases due to religious beliefs regardless of whether there was a low or severe risk of an abnormal clinical phenotype. These findings indicate that both severity of abnormality and religiosity play an important role in genetic counseling patients’ decision‐making processes and outcomes in Turkey. In addition, the findings suggest the need for legislation that reduces the differences in approaches between the physicians and institutions regarding parental decision‐making to terminate or continue a pregnancy in our country.
Mitochondrial chloride channels – What are they for?
Authors: Tomaskova Zuzana , Ondrias Karol
Published: January 2010

This minireview focuses on observation of the properties, functional significance, and modulation of single chloride channels in the mitochondrial inner membrane using two electrophysiological methods – the patch‐clamp and bilayer lipid membrane methods. Measurements of parameters such as conductance, Cl−/K+selectivity, voltage or pH dependence as well as their modulation by endogenous and exogenous compounds using individual mitochondrial chloride channels result in an unexpectedly wide range of values. This paper discusses the origin of this wide variety of channel parameters and the possible involvement of these channels in mitochondrial membrane potential oscillations, apoptosis, carrier function, and mitochondrial fusion and fission.
Contribution of voltage‐gated potassium channels to the regulation of apoptosis
Authors: Szabò Ildikò , Zoratti Mario , Gulbins Erich
Published: January 2010

Recent evidence points to the crucial involvement of voltage‐gated potassium channels (Kv) in apoptotic volume decrease and in the regulation of apoptosis in several systems. We have recently described the presence of a Kv channel, Kv1.3, in the mitochondria of lymphocytes. Expression of the channel correlated with increased sensitivity to apoptotic stimuli. Mitochondrial Kv1.3 contributes to the apoptotic cascade in T lymphocytes by interacting with pro‐apoptotic Bax resulting in alteration of mitochondrial functional parameters and ultimately, in cytochromecrelease. The present review summarizes the current understanding of the function of Kv channels in apoptosis in several cell types as well as the role of mitochondrial Kv1.3 in the regulation of cell death in lymphocytes.
X‐ray structures of the peridinin–chlorophyll‐protein reconstituted with different chlorophylls
Authors: Schulte Tim , Hiller Roger G. , Hofmann Eckhard
Published: January 2010

The peridinin–chlorophyll a‐protein (PCP) from dinoflagellates is a soluble light harvesting antenna which gathers incoming photons mainly by the carotenoid peridinin. In PCPs reconstituted with different chlorophylls, the peridinin to chlorophyll energy transfer rates are well predicted by a Förster‐like theory, but only if the pigment arrangements are identical in all PCPs. We have determined the X‐ray structures of PCPs reconstituted with Chlorophyll‐b (Chl‐b), Chlorophyll‐d (Chl‐d) and Bacteriochlorophyll‐a (BChl‐a) to resolutions ⩽2 Å. In all three cases the pigment arrangements are essentially the same as in native PCP. Hydrogen bonding is not responsible for preferential incorporation of “non‐native” chlorophylls over Chl‐a.
Anatomical Landmark Asymmetry Assessment in the Lumbar Spine and Pelvis: A Review of Reliability
Authors: Stovall Bradley Alan , Kumar Shrawan
Published: January 2010

The purpose of this article is to review current research investigating the reliability of bony anatomical landmark positional asymmetry assessment in the lumbar spine and pelvis, to determine the agreement on findings between authors, and to explore future directions in the area to address the significant issues. The databases MEDLINE, CINAHL, AMED, MANTIS, Academic Search Complete, and Web of Knowledge were searched. A total of 23 articles were identified and reviewed, 10 of which met the inclusion criteria. For these 10 articles, the average interexaminer reliability for bony anatomical landmark positional asymmetry assessment was slightly above chance for all landmarks except medial malleolus, which had fair reliability. Interexaminer reliability on average was less than intraexaminer reliability (anterior superior iliac spine, k = 0.128/0.414; posterior superior iliac spine, k = 0.092/0.371). All interexaminer reliability averages were below values of clinical significance. From the current literature review, bony anatomical landmark positional asymmetry assessment in the lumbar spine and pelvis has not been demonstrated to be a reliable assessment method. However, there are unexplored factors that, after standardization, may improve reliability and further the understanding of musculoskeletal palpatory examination.
Constructing a Competitive Order
Authors: Mercer Helen
Published: January 2010

This book was first published in 1995. Businessmen have always had a strong inclination to avoid competition and regulate the market. Helen Mercer traces the evolution of British competition legislation designed to discourage such practices, from 1900 to 1964. Economic and legal textbooks attribute the dynamic behind the development of this legislation to an undefined 'public opinion' or to economists. Helen Mercer disagrees. She contends that competition policies have been shaped by the strategies of powerful business interests - at home and in the United States. Trade unions and organisations of labour have provided a consistent pressure on governments to legislate on private monopoly, in the face of sweeping criticisms of free enterprise. This book makes extensive use of archival sources to give a detailed analysis of government-industry relations. In the course of this it sheds new light on Britain's changing industrial structure, and offers pointers to the likely outcome of business regulation in Britain in the future.
Histories of City and State in the Persian Gulf
Authors: Fuccaro Nelida
Published: January 2010

In this path-breaking and multi-layered account of one of the least explored societies in the Middle East, Nelida Fuccaro examines the political and social life of the Gulf city and its coastline, as exemplified by Manama in Bahrain. Written as an ethnography of space, politics and community, it addresses the changing relationship between urban development, politics and society before and after the discovery of oil. By using a variety of local sources and oral histories, Fuccaro questions the role played by the British Empire and oil in state-making. Instead, she draws attention to urban residents, elites and institutions as active participants in state and nation building. She also examines how the city has continued to provide a source of political, social and sectarian identity since the early nineteenth century, challenging the view that the advent of oil and modernity represented a radical break in the urban past of the region.
Black Nationalism in American Politics and Thought
Authors: Robinson Dean E.
Published: January 2010

Black Nationalism in American Politics and Thought revisits the activism and arguments in support of separate black statehood from the mid-nineteenth century to the present, detailing the ways black nationalism historically mirrors broader currents in US politics and thought. This book challenges the idea that black nationalism is an essentially timeless, unchanging, and anti-assimilationist impulse with respect to the alternative goal of racial inclusion. It argues that black nationalism in the United States draws on analogous political strategy and thinking unique to specific historical eras – often inadvertently reproducing strategies and thinking responsible for racial inequality in the first place.
Grammar, Gesture, and Meaning in American Sign Language
Authors: Liddell Scott K.
Published: January 2010

In sign languages of the deaf some signs can meaningfully point toward things or can be meaningfully placed in the space ahead of the signer. This obligatory part of fluent grammatical signing has no parallel in vocally produced languages. This book focuses on American Sign Language to examine the grammatical and conceptual purposes served by these directional signs. It guides the reader through ASL grammar, the different categories of directional signs, the types of spatial representations signs are directed toward, how such spatial conceptions can be represented in mental space theory, and the conceptual purposes served by these signs. The book demonstrates a remarkable integration of grammar and gesture in the service of constructing meaning. These results also suggest that our concept of 'language' has been much too narrow and that a more comprehensive look at vocally produced languages will reveal the same integration of gestural, gradient, and symbolic elements.
History and Memory in the Carolingian World
Authors: McKitterick Rosamond
Published: January 2010

The writing and reading of history in the early Middle Ages form the key themes of this 2004 book. The primary focus is on the remarkable manifestations of historical writing in relation to historical memory in the Frankish kingdoms of the eighth and ninth centuries. It considers the audiences for history in the Frankish kingdoms, the recording of memory in new genres including narrative histories, cartularies and Libri memoriales, and thus particular perceptions of the Frankish and Christian past. It analyses both original manuscript material and key historical texts from the Carolingian period, a remarkably creative period in the history of European culture. Presentations of the past developed in this period were crucial in forming an historical understanding of the Greco-Roman and Judaeo-Christian past and, in subsequent centuries, of early medieval Europe. They also played an extraordinarily influential role in the formation of political ideologies and senses of identity within Europe.
Perspectives on Labour Law
Authors: Davies A. C. L.
Published: January 2010

Policy discussions play an important role in labour law, and labour lawyers draw on a wide range of disciplines and approaches in order to construct their arguments. This overview of the basic principles of labour law and the related policy arguments introduces two of the main perspectives used in the analysis of labour law today – human rights and economics. It offers a brief history of the influence of human rights and economics on labour law since the 1950s, explains neoclassical and new institutional economics and summarises the historical development of international human rights law. The insights of rights theorists and economists are then applied to a selection of topics in labour law, including anti-discrimination law, dismissal, working time, pay, consultation and collective bargaining, trade union membership and industrial action, in order to demonstrate the interplay between the two perspectives.
Budgetary Decisions
Authors: Kraan Dirk-Jan , Tullock Gordon
Published: January 2010

This book provides an introduction to the positive theory of the budgetary process based on the theory of public choice. Although budgetary institutions are very diverse, both between and within countries, it is possible to identify key elements which are common to all forms of representative government. The author identifies these key elements as the supply of services by public agencies; demand for services by political bodies (cabinet, houses of parliament, etc); negotiations between administrators of agencies and political bodies in an 'internal market'; and decision-making in the form of budgetary and substantive legislation. The book develops a step-by-step model which incorporates all these elements, a model which can be used to explain and predict budgetary decisions in existing institutions, as well as to analyze institutional change, including cost budgeting and various forms of privatization.
Aristophanes the Democrat
Authors: Sidwell Keith
Published: January 2010

This book provides a new interpretation of the nature of Old Comedy and its place at the heart of Athenian democratic politics. Professor Sidwell argues that Aristophanes and his rivals belonged to opposing political groups, each with their own political agenda. Through disguised caricature and parody of their rivals' work, the poets expressed and fuelled the political conflict between their factions. Professor Sidwell rereads the principal texts of Aristophanes and the fragmented remains of the work of his rivals in the light of these arguments for the political foundations of the genre.
Evaluating the quality of dietary intake validation studies
Authors: Serra-Majem Lluis , Frost Andersen Lene , Henríque-Sánchez Patricia , Doreste-Alonso Jorge , Sánchez-Villegas Almudena , Ortiz-Andrelluchi Adriana , Negri Eva , La Vecchia Carlo
Published: January 2010

Within the EURopean micronutrient RECommendations Aligned Network of Excellence (EURRECA), a scoring system was developed to assess the quality of dietary intake validation studies. The scoring system included three steps. The first step was to give each study a quality score, which included five components: sample size, statistics used, data collection procedure, consideration of seasonality and supplement use. Scores ranged from 0 to 7, and validation studies classified as very good ( ≥ 5), good (5–3·5), acceptable/reasonable (3·5–2·5) and poor ( < 2·5). The second and third steps included an adjustment/weighting of the correlation coefficient according to the quality score and moreover a rating of the adjusted/weighted correlation. The scoring system was tested in 124 validation studies that included at least one vitamin. Only 5·6 % of the 124 studies were judged to be of very good quality according to the quality score, 41·9 % of good quality and 16·9 % had a poor rating. When adjusting for the study quality scores, crude and adjusted mean correlations of vitamins A, C, D and E intakes were similar, but the percentage of correlation values classified as poor or very good was higher after adjustment. These results show the importance of considering the quality of studies validating dietary assessment methods and the correlations obtained for the micronutrient of interest when interpreting effects observed in epidemiological studies using dietary assessment methods. Without a doubt, this subject constitutes a key topic for research in nutritional epidemiology.