bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hemodynamics of the posterior cerebral arteries in neonates with periventricular leukomalacia
Authors: Fukuda Sumio , Kuwabara Satomi , Yasuda Mari , Mizuno Keisuke , Kato Takenori , Sugiura Takahiro , Hussein Mohamed Hamed , Kato Ineko , Fujimoto Shinji , Sobajima Hisanori , Togari Hajime 
Published: December 2004

AbstractPurposeThe purpose of this study was to evaluate the cerebral blood flow of the posterior cerebral arteries (PCAs) in neonates in relation to the onset of periventricular leukomalacia (PVL).MethodsAmong 57 low‐birth‐weight neonates studied, 7 were diagnosed with PVL with cyst formation on sonography and MRI. The mean cerebral blood flow velocity (CBFV) was measured in all the neonates by Doppler sonography through the posterior fontanel separately in the right and left PCA at days 0, 1, 2, 3, 4, 5, 7, 10, 14, 21, 28, 42, 56, and 70 following birth.ResultsIn the 7 neonates with PVL the mean CBFV in the right PCA was significantly lower than that in neonates without PVL at days 10, 14, 21, 28, 42, 56, and 70; the mean CBFV in the left PCA of neonates with PVL was significantly lower than that in those without PVL at days 7, 10, 14, 21, 28, 42, 56, and 70. CBFV measured in neonates without PVL exhibited a gradual increase postnatally. In contrast, CBFV values for neonates with PVL plateaued after day 5 or 7.ConclusionsThe serial measurement of PCA CBFV postnatally may prove useful as a predictor of the development of PVL. © 2004 Wiley Periodicals, Inc. J Clin Ultrasound 33:24–28, 2005
Sonographic demonstration of the normal thoracic esophagus
Authors: Zhu Shang‐Yong , Liu Ruo‐Chuan , Chen Li‐Hong , Luo Feng , Yang Hong , Feng Xu , Liao Xin‐Hong 
Published: December 2004

AbstractPurposeAlthough conventional sonography has been used widely in evaluation of the abdominal and cervical esophagus, its use in the thoracic esophagus is seldom mentioned. The aim of this study was to assess whether conventional sonography could demonstrate the thoracic esophagus and to determine this structure's normal sonographic appearance and measurements.MethodsTransthoracic sonography was performed in 253 healthy volunteers ranging in age from 12 to 72 years (mean, 41 ± 15 years). The subjects were examined while supine with their hands raised over their heads; the transducer was placed along the left side of the sternum sequentially from the first to the fifth intercostal spaces. The ultrasound beam was directed to the thoracic aorta using the heart as an acoustic window. The detectable length of the thoracic esophagus was measured in the longitudinal scan from the upper most part visualized to the point at which it penetrated the diaphragm. The esophageal thickness was measured on the anterior wall at the level of the left atrium.ResultsIn 188 (74%) of the 253 subjects, the thoracic esophagus could be demonstrated by sonography, except for the portion under the first and second intercostal spaces. In 3 of these 188 subjects, the esophagus also was not visualized at the third intercostal space. In these 188 subjects, the esophageal wall was shown as 3 layers. The esophageal lumen appeared as 1 or 2 hyperechoic bands in longitudinal sonograms. In 163 subjects, gas artifact and the comet‐tail sign, with downward movement, were seen in the esophageal lumen after swallowing. The mean demonstrable length of the thoracic esophagus was 10.2 ± 1.9 cm and the mean thickness 3.2 ± 0.3 mm.ConclusionsMost of the thoracic esophagus can be visualized by sonography, except for a short portion at the back of the left main bronchus. The heart and the thoracic aorta are 2 important landmarks in scanning. © 2004 Wiley Periodicals, Inc. J Clin Ultrasound 33:29–33, 2005
Estrogen promotes differentiation and survival of dopaminergic neurons derived from human neural stem cells
Authors: Kishi Yo , Takahashi Jun , Koyanagi Masaomi , Morizane Asuka , Okamoto Yo , Horiguchi Satoshi , Tashiro Kei , Honjo Tasuku , Fujii Shingo , Hashimoto Nobuo 
Published: December 2004

AbstractTo investigate the effect of estrogen on neuronal differentiation, especially on dopaminergic (DA) neurons, human neural stem cells (NSCs) were differentiated in the presence of 17β‐estradiol. NSCs gave rise to tyrosine hydroxylase (TH)‐positive neurons in vitro, the proportion of which was increased by 17β‐estradiol. Increase in TH‐positive neurons was abrogated by an estrogen receptor (ER) antagonist, ICI182780, suggesting ERs play a role in differentiation of DA neurons. The observation that ERs were expressed in both proliferating NSCs and postmitotic DA neurons suggested that increase in TH‐positive neurons was due to induction and support of DA neurons. 17β‐Estradiol also increased the number of DA neurons derived from human NSCs in vivo when the cells were grafted into mouse brains. These results support a possible role for estrogen in the transplantation of NSCs for Parkinson's disease. © 2004 Wiley‐Liss, Inc.
Modulation of hypoglycemia‐induced increases in plasma epinephrine by estrogen in the female rat
Authors: Adams Julye M. , Legan Sandra J. , Ott Cobern E. , Jackson Brian A. 
Published: December 2004

AbstractClinical studies have demonstrated that estrogen replacement therapy suppresses stress‐induced increases in plasma catecholamines. The present study determined whether normal circulating levels of estrogen can modulate hypoglycemia‐induced increases in plasma epinephrine (EPI). In anesthetized female rats, insulin‐induced hypoglycemia (0.25 U/kg) increased plasma EPI concentration to a significantly greater extent in 14‐day ovariectomized (OVEX) rats compared to that in sham‐operated controls. In 17β‐estradiol (E2)‐replaced OVEX rats, the hypoglycemia‐induced rise in plasma EPI was reduced significantly when compared to that in vehicle‐replaced OVEX rats. OVEX and E2 replacement had no effect on tyrosine hydroxylase or phenylethanolamine N‐methyltransferase mRNA levels in the adrenal medulla. In isolated adrenal medullary chromaffin cells, agonist‐induced increases in intracellular Ca2+ were unaffected by 48‐hr exposure to 10 nM E2. In contrast, acute (3‐min) exposure to micromolar concentrations of E2 dose‐dependently and reversibly inhibited agonist‐induced Ca2+ transients. In addition, in OVEX rats, a constant infusion of E2 significantly reduced the insulin‐induced increase in plasma EPI concentration compared to that in vehicle‐infused controls. These data demonstrate that physiologic levels of circulating E2 can modulate hypoglycemia‐induced increases in plasma EPI. This effect seems independent of steroid influence on adrenal medullary secretion or biosynthesis. In contrast, acute exposure to high levels of E2 can also suppress hypoglycemia‐induced increases in plasma epinephrine, due at least in part to inhibition of stimulus‐secretion coupling. © 2004 Wiley‐Liss, Inc.
Stimulation of G‐proteins in human control and Alzheimer's disease brain by FAD mutants of APP714–723: Implication of oxidative mechanisms
Authors: Karelson Ello , Fernaeus Sandra , Reis Katarina , Bogdanovic Nenad , Land Tiit 
Published: December 2004

AbstractWe report the effects of amyloid precursor protein (APP) fragment 714–723 (APP714–723; peptide P1) and its V717F and V717G mutants (peptides P2 and P3, respectively) on G‐protein activity ([35S]GTPγS binding) in membranes from postmortem human control and Alzheimer's disease (AD) brains. The peptides P1, P2, and P3 revealed a significant stimulatory effect on [35S]GTPγS binding in control temporal cortex. The most potent stimulator, P3, at 10 μM concentration enhanced [35S]GTPγS binding by 500%. The effect was threefold stronger than that for wild‐type P1 and twofold stronger than that for P2. In sporadic AD, the stimulatory effect of P1, P2, and P3 on G‐proteins was reduced significantly whereas in Swedish familial AD (SFAD), only P1 elicited marked stimulation (at 10 μM by 50%). In control sensory postcentral cortex, the stimulation of G‐proteins by P3 was 1.5‐fold lower than that in control temporal cortex, whereas in AD and SFAD the effect showed no remarkable regional difference. Treatment of membranes with H2O2 produced 1.5‐fold higher stimulation in [35S]GTPγS binding to temporal cortex than that in binding to sensory postcentral cortex. In AD and SFAD, the stimulation by H2O2 revealed no significant regional difference. Glutathione, desferrioxamine (DFO), and 17β‐estradiol markedly decreased the strong stimulatory effect by P3 on [35S]GTPγS binding to control temporal cortex, with the protective effect by DFO being most potent. The Gαo‐protein levels were not changed in AD or SFAD brain membranes as compared to levels in control membranes. We suggest that strong G‐protein stimulation by P3 in the human brain implies the specific (per)oxidation mechanism that might be affected by regional content of peroxidizing substrates and antioxidants. © 2004 Wiley‐Liss, Inc.
Metallothionein reduces central nervous system inflammation, neurodegeneration, and cell death following kainic acid‐induced epileptic seizures
Authors: Penkowa Milena , Florit Sergi , Giralt Mercedes , Quintana Albert , Molinero Amalia , Carrasco Javier , Hidalgo Juan 
Published: December 2004

AbstractWe examined metallothionein (MT)‐induced neuroprotection during kainic acid (KA)‐induced excitotoxicity by studying transgenic mice with MT‐I overexpression (TgMT mice). KA induces epileptic seizures and hippocampal excitotoxicity, followed by inflammation and delayed brain damage. We show for the first time that even though TgMT mice were more susceptible to KA, the cerebral MT‐I overexpression decreases the hippocampal inflammation and delayed neuronal degeneration and cell death as measured 3 days after KA administration. Hence, the proinflammatory responses of microglia/macrophages and lymphocytes and their expression of interleukin (IL)‐1, IL‐6, IL‐12, tumor necrosis factor‐α and matrix metalloproteinases (MMP‐3, MMP‐9) were significantly reduced in hippocampi of TgMT mice relative to wild‐type mice. Also by 3 days after KA, the TgMT mice showed significantly less delayed damage, such as oxidative stress (formation of nitrotyrosine, malondialdehyde, and 8‐oxoguanine), neurodegeneration (neuronal accumulation of abnormal proteins), and apoptotic cell death (judged by TUNEL and activated caspase‐3). This reduced bystander damage in TgMT mice could be due to antiinflammatory and antioxidant actions of MT‐I but also to direct MT‐I effects on the neurons, in that significant extracellular MT presence was detected. Furthermore, MT‐I overexpression stimulated astroglia and increased immunostaining of antiinflammatory IL‐10, growth factors, and neurotrophins (basic fibroblastic growth factor, transforming growth factor‐β, nerve growth factor, brain‐derived neurotrophic factor, glial‐derived neurotrophic factor) in hippocampus. Accordingly, MT‐I has different functions that likely contribute to the increased neuron survival and improved CNS condition of TgMT mice. The data presented here add new insight into MT‐induced neuroprotection and indicate that MT‐I therapy could be used against neurological disorders. © 2004 Wiley‐Liss, Inc.
Persistence of Hepatitis C Virus After Successful Treatment of Chronic Hepatitis C: Is Hepatitis C Infection for Life?
Authors: Radkowski Marek , Laskus Tomasz 
Published: December 2004

Abstract

It is presumed that resolution of hepatitis C, as evidenced by normalization of liver function tests and disappearance of hepatitis C virus (HCV) RNA from serum, as determined by conventional laboratory assays, reflects virus eradication. In this study, we examined the expression of the HCV genome in the sera, peripheral blood mononuclear cells (PBMC), and, on some occasions, monocyte-derived dendritic cells (DC) long after resolution of hepatitis C by using a highly sensitive reverse transcription (RT)-polymerase chain reaction-nucleic acid hybridization (RT-PCR-NAH) assay. The samples obtained from 16 randomly selected patients (5 with spontaneous resolution and 11 with treatment-induced resolution), monitored for up to 5 years, were studied by qualitative and semiquantitative RT-PCR-NAH and by real-time RT-PCR to detect the HCV RNA positive strand. The replicative HCV RNA negative strand was examined in PBMC after culture with a T cell proliferation stimulating mitogen. The findings show that HCV RNA was carried in the convalescent-phase sera and/or PBMC in all 16 individuals investigated. Also, DC from six of seven patients were reactive for the HCV genome. Importantly, traces of the HCV RNA negative strand, suggesting progressing virus replication, were detected in the majority of mitogen-stimulated PBMC, including four samples collected 5 years after recovery. Sequencing of the HCV 5' untranslated region fragment revealed genotype 1b in four of nine individuals examined and genotypes 1a and 2a in three and two patients, respectively. In conclusion, these results imply that HCV RNA can persist at very low levels in the serum and peripheral lymphoid cells and that an intermediate replicative form of the HCV genome can persist in PBMC for many years after apparently complete spontaneous or antiviral therapy-induced resolution of chronic hepatitis C. (J Virol 2004;78:5867–5874.)
Diffusion tensor imaging of in vivo and excised rat spinal cord at 7 T with an icosahedral encoding scheme
Authors: Madi Saaussan , Hasan Khader M. , Narayana Ponnada A. 
Published: December 2004

AbstractRegional values of fractional anisotropy (FA) and mean diffusivity (Dav) of in vivo and excised rat spinal cords were measured using an iscosahedral encoding scheme that is based on 21 uniformly distributed and alternating gradient directions with an echo planar imaging (EPI) readout. Based on the water phantom studies, this scheme was shown to provide unbiased estimation of FA. The stability of the scanner during the acquisition of diffusion tensor imaging (DTI) data was evaluated. Repeated measurements of the FA values demonstrated excellent reproducibility, as assessed by the Bland–Altman analysis. These studies demonstrated a reduced anisotropy in excised samples relative to in vivo cords. Diffusion in the spinal cord gray matter was shown to be anisotropic. The FA value in the dorsal white matter (WM) was found to be higher relative to the ventral WM. Results from these studies should provide the necessary baseline data for serial in vivo DTI of injured spinal cord. Magn Reson Med 53:118–125, 2005. © 2004 Wiley‐Liss, Inc.
Using the axis of rotation of polar navigator echoes to rapidly measure 3D rigid‐body motion
Authors: Costa Andreu F. , Petrie Daniel W. , Yen Yi‐Fen , Drangova Maria 
Published: December 2004

AbstractAn improved technique to prospectively correct three‐dimensional rigid‐body motion using polar spherical navigator (pNAV) echoes is presented. The technique is based on acquiring pNAVs of an object in a baseline and rotated position and determining the axis of rotation (AOR) between data sets, thereby reducing 3D rotations to a 2D, planar rotation. Finding the AOR is simplified by prerotating the baseline trajectory, which forces the axis to lie within a specific polar region of a spherical shell in k‐space. Orbital navigator echoes are interpolated from the pNAV data in planes orthogonal to the AOR and cross‐correlated to determine the 2D rotation. The rotation about the AOR is used in conjunction with its orientation to calculate the overall 3D rotation. The pNAV‐AOR technique was tested for its precision, accuracy, and processing speed in detecting compound rotations and translations of varying magnitude. In comparison to the spherical navigator echo technique, the pNAV‐AOR technique is noniterative, fast, and independent of rotation magnitude and direction. At low SNR, the technique can detect compound rotations to 0.5° accuracy in an estimated 100 msec, indicating that prospective 3D rigid‐body motion correction may be feasible with this technique. Magn Reson Med 53:150–158, 2005. © 2004 Wiley‐Liss, Inc.
Analytical approach to noncircular section birdcage coil design: Verification with a Cassinian oval coil
Authors: De Zanche Nicola , Yahya Atiyah , Vermeulen Fred. E. , Allen Peter S. 
Published: December 2004

AbstractA general analytical framework is presented for the design of birdcage radiofrequency resonators on cylindrical formers having arbitrary cross‐sectional shape. The primary objective of such shapes would be to improve the sensitivity of the NMR experiment to noncircular regions of the human anatomy while maintaining field homogeneity and quadrature polarization comparable to those of standard circular birdcage coils. The shape of the corresponding radiofrequency screen, which is required to decouple the coil from the rest of the NMR system and which is key to the performance, is also provided by this methodology. The theory was tested by constructing a 3‐T, quadrature, proton coil on a shape conforming to the anthropomorphic mean of the human head, namely, the oval of Cassini. Both bench tests (Q) and in vivo spectral and imaging comparisons of the Cassinian coil with an equivalently dimensioned and constructed circular birdcage coil, respectively, predicted and demonstrated in vivo an improvement in SNR of ∼24% over the circular section coil. The experimental RF field homogeneity and quadrature performance were comparable for both coil geometries, with the circular coil being marginally superior. Magn Reson Med 53:201–211, 2005. © 2004 Wiley‐Liss, Inc.
Retrospective coregistration of functional magnetic resonance imaging data using external monitoring
Authors: Tremblay Marleine , Tam Fred , Graham Simon J. 
Published: December 2004

AbstractCoregistration is essential for correcting head motion artifacts in functional magnetic resonance imaging (fMRI). Coregistration algorithms typically realign images through optimization of a similarity measure based on voxel signal intensities. However, coregistration can also be performed through external monitoring, whereby a tracking device measures head motion directly and independently of the imaging data. This paper describes development of external monitoring using fMRI‐compatible infrared cameras. Three subjects participated in block‐design fMRI experiments consisting of bilateral finger tapping alone and tapping combined with visuomotor tracking to produce controlled task‐correlated head motion. Functional MRI time‐series were coregistered using the external monitoring technique and a known image‐based algorithm for comparison. Over various performance characteristics, external monitoring and image‐based coregistration exhibited good agreement, in particular reducing signals correlated with millimeter task‐correlated motions by 50–100%, with a 5% difference between the two techniques. These results promise future applications and refinements of external monitoring in patient populations where head motion is especially problematic. Possibilities include 3D prospective coregistration during real‐time fMRI, coregistration of individual slices, and motion correction in anatomic MRI. Magn Reson Med 53:141–149, 2005. © 2004 Wiley‐Liss, Inc.
Sensitivity encoding as a means of enhancing the SNR efficiency in steady‐state MRI
Authors: Weiger Markus , Boesiger Peter , Hilfiker Paul R. , Weishaupt Dominik , Pruessmann Klaas P. 
Published: December 2004

AbstractSensitivity encoding (SENSE) with a receiver coil array is typically used as a means of reducing the scan time in MRI. The speed benefit usually comes at some expense in terms of the signal‐to‐noise ratio (SNR) efficiency, which has been notorious as the main downside of SENSE and parallel MRI in general. In this work it is shown that in steady‐state gradient‐echo imaging the parallel approach may as well be used to increase the SNR efficiency. The basic idea is to balance reduced phase encoding by increasing the repetition time. In this fashion both the acquisition duty cycle and the steady‐state magnetization can be enhanced, resulting in considerable net gains in SNR yield. It is argued that the reduction factor in parallel imaging is essentially an additional degree of freedom in optimizing the SNR. The optimal SENSE factor depends on scan, tissue, and hardware parameters, assuming values up to 3.0 and higher. The achievable SNR benefit also depends on the spoiling regime and is most pronounced for RF‐spoiled techniques. The proposed mechanism is demonstrated by simulations and phantom experiments, as well as by contrast‐enhanced angiography in vivo, achieving an approximate doubling of the SNR efficiency. Magn Reson Med 53:177–185, 2005. © 2004 Wiley‐Liss, Inc.
Dual‐velocity continuously moving table acquisition for contrast‐enhanced peripheral magnetic resonance angiography
Authors: Kruger David G. , Riederer Stephen J. , Polzin Jason A. , Madhuranthakam Ananth J. , Hu Houchun H. , Glockner James F. 
Published: December 2004

AbstractAcquisition of MR angiographic data of the peripheral vasculature during continuous table motion offers certain advantages over fixed station approaches, such as the elimination of wasted time moving between stations and the ability to form a seamless image of the extended field of view. However, it has recently been demonstrated that there is an approximate twofold reduction in contrast bolus velocity as it moves from the thighs to the calves. This can potentially cause a mismatch of the moving table with the contrast peak, resulting in the table outpacing the contrast bolus distally. In this work we describe a modification to the continuous table motion technique allowing two table velocities: a high (ca. 3.6 cm/sec) velocity from the abdomen to the thighs and a low (ca. 1.6 cm/sec) velocity distally. Implications of the nonconstant velocity on k‐space sampling are described, and it is shown that lateral resolution is improved for the low‐velocity region. Correction for table deceleration during the transition time between high and low velocities is demonstrated. Contrast‐enhanced studies in 15 volunteers are free of table‐motion‐related artifact and suggest improved depiction of the contrast bolus distally. Magn Reson Med 53:110–117, 2005. © 2004 Wiley‐Liss, Inc.
Hyperpolarized 3He lung imaging at 0.5 and 1.5 Tesla: A study of susceptibility‐induced effects
Authors: Salerno Michael , Brookeman James R. , de Lange Eduard E. , Mugler John P. 
Published: December 2004

AbstractHyperpolarized 3He MRI of the human lung was performed at 0.54 and 1.5 T using identical software and hardware (except for RF coils) at both field strengths. The T of 3He gas in the lung was measured, and the effects of magnetic‐susceptibility‐induced field inhomogeneities on the appearance of interleaved‐spiral and interleaved‐echo‐planar lung images at 1.5 T were compared to those at 0.54 T. Mean T values for 3He gas in the healthy human lung were 26.8 ± 1.5 ms and 67.9 ± 1.3 ms at 1.5 and 0.54 T, respectively. At 0.54 T, interleaved‐spiral images showed markedly less blurring due to susceptibility effects compared to images acquired at 1.5 T. At both 0.54 and 1.5 T, interleaved‐echo‐planar images appeared essentially identical to corresponding GRE images, even though the data‐sampling period per echo and echo time were substantially longer for the interleaved‐echo‐planar images acquired at 0.54 T. Magn Reson Med 53:212–216, 2005. © 2004 Wiley‐Liss, Inc.