bluuebunny/crossref_metadata_2025_split huggingface dataset:
Time course analysis of gene expression during light‐induced photoreceptor cell death and regeneration in albino zebrafish
Authors: Kassen Sean C. , Ramanan Vijay , Montgomery Jacob E. , T. Burket Christopher , Liu Chang‐Gong , Vihtelic Thomas S. , Hyde David R. 
Published: March 2007

AbstractConstant intense light causes apoptosis of rod and cone photoreceptors in adult albino zebrafish. The photoreceptors subsequently regenerate from proliferating inner nuclear layer (INL) progenitor cells that migrate to the outer nuclear layer (ONL) and differentiate into rods and cones. To identify gene expression changes during this photoreceptor regeneration response, a microarray analysis was performed at five time points during the light treatment. The time course included an early time point during photoreceptor death (16 h), later time points during progenitor cell proliferation and migration (31, 51, and 68 h) and a 96 h time point, which likely corresponds to the initial photoreceptor differentiation. Mean expression values for each gene were calculated at each time point relative to the control (0 h light exposure) and statistical analysis by one‐way ANOVA identified 4567 genes exhibiting significant changes in gene expression along the time course. The genes within this data set were clustered based on their temporal expression patterns and proposed functions. Quantitative real‐time PCR validated the microarray expression profiles for selected genes, including stat3 whose expression increased markedly during the light exposure. Based on immunoblots, both total and activated Stat3 protein expression also increased during the light treatment. Immunolocalization of Stat3 on retinal tissue sections demonstrated increased expression in photoreceptors and Müller glia by 16 h of light exposure. Some of the Stat3‐positive Müller cells expressed PCNA at 31 h, suggesting that Stat3 may play a role in signaling a subset of Müller cells to proliferate during the regeneration response. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007.
Kidney development and gene expression in the HIF2α knockout mouse
Authors: Steenhard Brooke M. , Freeburg Paul B. , Isom Kathryn , Stroganova Larysa , Borza Dorin‐Bogdan , Hudson Billy G. , St. John Patricia L. , Zelenchuk Adrian , Abrahamson Dale R. 
Published: March 2007

AbstractThe hypoxia‐inducible transcription factor‐2 (HIF2), a heterodimer composed of HIF2α and HIF1β subunits, drives expression of genes essential for vascularization, including vascular endothelial growth factor (VEGF) and VEGF receptor‐2 (VEGFR‐2, Flk‐1). Here, we used a HIF2α/LacZ transgenic mouse to define patterns of HIF2α transcription during kidney development and maturation. Our results from embryonic heterozygotes showed HIF2α/LacZ expression by apparently all renal endothelial cells. At 4 weeks of age, glomerular mesangial and vascular smooth muscle cells were also positive together with endothelial cells. These expression patterns were confirmed by electron microscopy using Bluo‐gal as a β‐galactosidase substrate. Small numbers of glomerular and tubular epithelial cells were also positive at all stages examined. Light and electron microscopic examination of kidneys from HIF2α null embryos showed no defects in renal vascular development or nephrogenesis. Similarly, the same amounts of Flk‐1 protein were seen on Western blots of kidney extracts from homozygous and heterozygous HIF2α mutants. To examine responsiveness of HIF2α null kidneys to hypoxia, embryonic day 13.5 metanephroi were cultured in room air or in mild (5% O2) hypoxia. For both heterozygous and null samples, VEGF mRNA levels doubled when metanephroi were cultured in mild hypoxia. Anterior chamber grafts of embryonic HIF2α knockouts were morphologically indistinguishable from heterozygous grafts. Endothelial markers, platelet endothelial cell adhesion molecule and BsLB4, as well as glomerular epithelial markers, GLEPP1 and WT‐1, were all expressed appropriately. Finally, we undertook quantitative real‐time polymerase chain reaction of kidneys from HIF2α null embryos and wild‐type siblings and found no compensatory up‐regulation of HIF1α or ‐3α. Our results show that, although HIF2α was widely transcribed by kidney endothelium and vascular smooth muscle, knockouts displayed no detectable deficits in vessel development or VEGF or Flk‐1 expression. Developmental Dynamics 236:1115–1125, 2007. © 2007 Wiley‐Liss, Inc.
Highly Organosoluble Metal‐Free Phthalocyanines and Metallophthalocyanines: Synthesis and Characterization
Authors: Bilgin Ahmet , Ertem Beytullah , Gök Yaşar 
Published: March 2007

AbstractThe syntheses and characterization of metal‐free and metal‐containing (Zn and Ni) derivatives of a symmetrically octa‐substituted phthalocyanine derived from 4,5:12,13‐bis(4′‐tert‐butylbenzo)‐8,9‐(4″,5″‐dicyanobenzo)‐6,11‐ditosyl‐6,11‐diaza‐2,15‐dithiacyclohexadeca‐4,8,12‐triene and CuPc from 4,5:12,13‐bis(4′‐tert‐butylbenzo)‐8,9‐(4″,5″‐dibromobenzo)‐6,11‐ditosyl‐6,11‐diaza‐2,15‐dithiacyclohexadeca‐4,8,12‐triene were carried out. Pentanuclear silver(I) and palladium(II) complexes have also been prepared from nickel(II) phthalocyaninate derivatives. The prepared phthalocyanines were semiconducting materials in the range of 10–5 to10–10 S cm–1 in vacuo and under atmospheric pressure. The extraction abilities of NiPc and detosylated phthalocyanines were evaluated in chloroform/water by using several heavy‐metal picrates such as Ag+, Cd2+, Cu2+, Hg2+, Pb2+, Pd2+, and Zn2+. The extraction affinities of NiPc and detosylated phthalocyanines for Ag+ were found to be the highest in solvent extraction experiments. The new compounds were characterized by using elemental analysis, UV/Vis, FTIR, NMR, MS spectroscopic data and DTA/TG. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
m‐Terphenylaluminum and ‐gallium Compounds: Synthesis and Conversion into Low‐Coordinate Organogallium Cations
Authors: Young Jackie D. , Khan Masood A. , Powell Douglas R. , Wehmschulte Rudolf J. 
Published: March 2007

AbstractThe reaction of two or 3 equiv. of m‐terphenyllithium with MCl3 or AlH3·NMe3 (M = Al, Ga) affords the bis(terphenyl)aluminum and ‐gallium chloride compounds [{2,6‐(4‐tBuC6H4)2C6H3}2GaCl] (1), [{2,6‐(3,5‐Me2C6H3)2C6H3}2GaCl] (2), [{2,6‐(4‐tBuC6H4)2C6H3}3Ga] (3), [(2,6‐Mes2C6H3)2AlCl] (5), and [(2,6‐Mes2C6H3)2AlH] (7; Mes = 2,4,6‐Me3C6H2). While the gallium compounds can be obtained at room temperature, heating is required for the aluminum derivatives. The dibutyl compounds [(2,6‐Mes2C6H3)GaBu2] (8) and[(2,6‐Dipp2C6H3)GaBu2] (9; Dipp = 2,6‐iPr2C6H3) have also been synthesized by the reaction of m‐terphenyllithium with ClGaBu2. A metathesis reaction of 2 with Li[Al{OCH(CF3)2}4] gives the ionic species [(2,6‐Mes2C6H3)2Ga]+[Li{Al[OCH(CF3)2]4}2]– (11). The cationic butyl(terphenyl)gallium compounds [(2,6‐Mes2C6H3)GaBu]+ ([13]+) and [(2,6‐Dipp2C6H3)GaBu]+ ([14]+) have been prepared by butanide abstraction with the trityl salts of the weakly coordinating anions [B(C6F5)4]–, [CHB11Br6Me5]–, and [CHB11Cl11]–. These ionic species are stable at room temperature for days or weeks, although their combinations with the borate anion [B(C6F5)4]– suffer from C6F5 migration, which is slow at room temperature and faster at elevated temperatures. The compound [14]+[CHB11Cl11]– is stable at 70 °C for at least 23 h. Addition of 1‐octene to a solution of [14]+[CHB11Cl11]– in C6D6 results in olefin exchange and formation of the octyl species [(2,6‐Dipp2C6H3)Ga(octyl)]+ ([17]+), and a slow alkylation of the solvent to afford various octylbenzenes. Hydrolysis of 8 and [13]+[CHB11Br6Me5]– gives the compounds [{(2,6‐Mes2C6H3)GaBu(μ‐OH)}2] (10) and [(BuGa)4(μ‐OH)6]2+[CHB11Br6Me5]–2 (16). All compounds have been characterized by 1H and 13C{1H} NMR spectroscopy and mass spectrometry, and compounds 3, 5, 7, 10, and 16·4.5C6H6 have also been characterized by single‐crystal X‐ray crystallography. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Characterization of Coordination Compounds by Electrochemical Parameters
Authors: Pombeiro Armando J. L. 
Published: March 2007

AbstractAttention is drawn to the interest in the use of the redox potential for the characterization and identification of coordination compounds on the basis of redox potential‐structure relationships that define electrochemical parameters, which are shown for a wide variety of ligands and metal sites. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
The Binuclear Cyclopentadienylvanadium Carbonyls (η5‐C5H5)2V2(CO)7 and (η5‐C5H5)2V2(CO)6: Comparison with Homoleptic Chromium Carbonyls
Authors: Zhang Xiuhui , Li Qian‐shu , Xie Yaoming , King R. Bruce , Schaefer III Henry F. 
Published: March 2007

AbstractThe cyclopentadienylvanadium carbonyls CpV(CO)n (n = 4, 3, 2, 1), Cp2V2(CO)7, and Cp2V2(CO)6 have been studied by density functional theory using the B3LYP and BP86 functionals. The optimized structure of CpV(CO)4 is close to that found experimentally by X‐ray and electron diffraction methods. For the coordinately unsaturated CpV(CO)n (n = 3, 2, 1) the computed ν(CO) frequencies by BP86 are related to those found in low‐temperature matrix isolation experiments but show some significant differences for n = 3 and 2 in band spacings suggesting some matrix effects on the geometries. An optimized structure for Cp2V2(CO)7 is found with one symmetrical bridging carbonyl group and a V–V distance of 3.306 Å (BP86) suggesting a single bond. Energetically competitive structures for Cp2V2(CO)6 include a doubly symmetrically bridged singlet structure with only two‐electron donor carbonyl groups, a triplet doubly semibridged structure, and a singlet structure with one four‐electron donor bridging carbonyl group. Thermodynamic considerations rationalize why neither Cp2V2(CO)7 nor Cp2V2(CO)6 have yet been synthesized. Thus Cp2V2(CO)7 is predicted to be unstable with respect to dissociation into CpV(CO)4 + CpV(CO)3. Furthermore, the dissociation energy of the lowest lying singlet isomer from Cp2V2(CO)6 to Cp2V2(CO)5 is only 10.8 kcal/mol (BP86) consistent with the formation of Cp2V2(CO)5 rather than Cp2V2(CO)6 upon decomposition of the presumed CpV(CO)3H2 dihydride generated by acidification of the dianion CpV(CO)32–.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Theoretical study of the vertical excited states of benzene, pyrimidine, and pyrazine by the symmetry adapted cluster—Configuration interaction method
Authors: Li Yongjian , Wan Jian , Xu Xin 
Published: March 2007

AbstractThe ground state and the excited states of benzene, pyrimidine, and pyrazine have been examined by using the symmetry adapted cluster‐configuration interaction (SAC‐CI) method. Detailed characterizations and the structures of the absorption peaks in the vacuum ultraviolet (VUV), low energy electron impact (LEEI), and electron energy loss (EEL) spectra were theoretically clarified by calculating the excitation energy and the oscillator strength for each excited state. We show that SAC‐CI has the power to well reproduce the electronic excitation spectra (VUV, LEEI, and EEL) simultaneously to an accuracy for both the singlet and the triplet excited states originated from the low‐lying π → π*, n → π*, π → σ* and n → σ* excited states of the titled compounds. The present results are compared with those of the previous theoretical studies by methods, such as EOM‐CCSD(T), STEOM‐CCSD, CASPT2 and TD‐B3LYP, etc. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
Theoretical studies on farnesyl transferase: Evidence for thioether product coordination to the active‐site zinc sphere
Authors: Sousa Sérgio Filipe , Fernandes Pedro Alexandrino , Ramos Maria João 
Published: March 2007

AbstractFarnesyltransferase (FTase), an interesting zinc metaloenzyme, has been the subject of great attention in anticancer research over the last decade. However, despite the major accomplishments in the field, some very pungent questions on the farnesylation mechanism still persist. In this study, the authors have analyzed a mechanistic paradox that arises from the existence of several contradicting and inconclusive experimental evidence regarding the existence of direct coordination between the active‐site zinc cation and the thioether from the farnesylated peptide product, which include UV–vis spectroscopy data on a Co2+‐substituted FTase, two X‐ray crystallographic structures of the FTase‐product complex, and extended X‐ray absorption fine structure results. Using high‐level theoretical calculations on two models of different sizes, and QM/MM calculations on the full enzyme, the authors have shown that the farnesylated product is Zn coordinated, and that a subsequent step where this Zn bond is broken is coherent with the available kinetic results. Furthermore, an explanation for the contradicting experimental evidence is suggested. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
Quick scheme for evaluation of atomic charges in arbitrary aluminophosphate sieves on the basis of electron densities calculated with DFT methods
Authors: Larin A. V. , Mortier W. J. , Vercauteren D. P. 
Published: March 2007

AbstractIt is demonstrated that unique and simple analytical functions are justified for the atomic charge dependences q of the T (T = Al, P) and O atoms of aluminophosphates (AlPOs) using DFT calculations with several basis sets, starting from STO‐3G to 3‐21G and 6‐21G**. Three internal (bonds, angles, …) coordinates for the charge dependences of the T atoms and four coordinates for the O are sufficient to reach a precision of 1.8% for the fitted q(Al), 1.0% for q(P), and 2.5% for q(O) relatively to the values calculated at any basis set level. The proposed strategy consists in an iterative scheme starting from charge dependences based on the neighbor's positions only. Electrostatic potential values are computed to illustrate the differences between the calculated and fitted charges in the considered AlPO models. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
Imaging of diffusion and microcirculation with gradient sensitization: Design, strategy, and significance
Authors: Le Bihan Denis , Turner Robert , Moonen Chrit T. W. , Pekar James 
Published: March 2007

AbstractRecent developments in the use of magnetic resonance (MR) to measure and image diffusion and blood microcirculation (“perfusion”) are summarized. After a brief description of the effects of diffusion and perfusion on the MR signal, the different methods (conventional spin‐echo, stimulated‐echo, gradient‐echo, and echo‐planar imaging) that have been proposed and used to image and measure diffusion and perfusion by gradient sensitization are presented, along with their advantages and limitations. The difficulties of diffusion/ perfusion imaging related to both hardware and software are then discussed. Special attention is given to specific problems encountered with in vivo studies and data analysis. Finally, the potential biologic and clinical applications are outlined, and some examples are presented.
Preliminary clinical trial of gadodiamide injection: A new nonionic gadolinium contrast agent for MR imaging
Authors: Kaplan Gabriela D. , Aisen Alex M. , Aravapalli S. Rao 
Published: March 2007

AbstractThe safety and efficacy of a newly developed intravenous formulation of the nonionic contrast agent gadolinium diethylenetriaminepentaacetic acid‐bis(methylamide), formulated as gadodia‐mide injection, was investigated. In 30 patients who underwent spin‐echo magnetic resonance (MR) imaging before and after contrast agent enhancement, the enhanced images had characteristics judged similar to those of images enhanced by means of available gadolinium compounds. In 15 patients, contrast agent administration was of major diagnostic help, either revealing lesions not apparent without enhancement or providing important lesion characterization. In 12 patients, the lack of abnormal enhancement patterns was important in excluding the presence of disease. In three patients, the contrast agent did not provide information additional to that obtained with the unenhanced T1‐ and T2‐weighted images. No clinically significant changes were observed in vital signs, neurologic status, or laboratory results. The authors conclude that, in this limited series, gadodiamide injection proved to be a safe and useful MR imaging contrast agent for evaluation of the central nervous system and surrounding structures.
MR imaging of patients with implanted drug infusion pumps
Authors: Roemeling Reinhard Von , Lanning Rosellen M. , Eames Frederick A. 
Published: March 2007

AbstractThe influence of magnetic resonance (MR) imaging on the integrity and function of an implantable, programmable drug infusion pump and the distortion of the image by this device were tested. Six identical pumps were tested in magnetic fields of 1.5 T. Pump memory was not affected by the procedure. The pump rotor stalled (no infusion) as long as the device was within the magnetic field. Drug delivery resumed as programmed after the pump was removed from the field. No structural damage to the electrical or mechanical pump components was detected. The pump caused a circular image artifact (a signal dropout) within 8–10 cm of the device. The authors conclude that MR imaging is accurate if the area of interest is at least 10 cm from the pump, and that with awareness of temporary infusion cessation, it is safe to perform MR imaging in patients with this implanted pump.
Direct hepatic tumor injection in rats: Can it be used for analysis of MR imaging contrast agents?
Authors: Murphy Frederick B. , del Pilar Fernandez Maria , Kossoff Marjorie B. , Dillehay Dirck L. , Malko John A. , Bernardino Michael E. 
Published: March 2007

AbstractWith a recently described rat model technique for direct hepatic injection of tumor cells for imaging research, there were concerns that the injection itself might produce lesions detectable with magnetic resonance (MR) imaging, thereby producing false‐positive results. To examine this possibility, the authors prospectively studied 14 Sprague‐Dawley rats after direct hepatic injection of cells from a rat hepatoma cell line. The rats were imaged with a variety of pulse sequences before and after intravenous injection of the contrast agent manganese dipyridoxal diphosphate at a dose of 8 μmol/kg. No intrahepatic lesions could be detected with MR imaging during the first 6 days after direct hepatic injection of the tumor cells. Therefore, the direct injection technique should be accurate for evaluating various MR imaging sequences and contrast agents for early hepatic tumor detection.
Interactive design of motion‐compensated gradient waveforms with a personal computer spreadsheet program
Authors: Wendt Richard E. 
Published: March 2007

AbstractA personal computer spreadsheet program was used to compute the amplitudes of the gradient pulses in motion‐compensated gradient waveforms. The resulting designs for velocity‐compensated, gradient‐echo, frequency‐encoding gradients and velocity‐compensated section‐select waveforms required little or no modification when implemented on two clinical magnetic resonance imagers.
Detection with echo‐planar MR imaging of transit of susceptibility contrast medium in a rat model of regional brain ischemia
Authors: Wendland Michael F. , White David L. , Aicher Klaus P. , Tzika A. Aria , Moseley Michael E. 
Published: March 2007

AbstractGradient‐refocused echo‐planar magnetic resonance (MR) images (TE = 18 msec) were acquired in rats during bolus injection of iron oxide particles, and the first pass of the contrast agent through the brain was monitored. In control rats, contrast agent (0.1 mmol/kg iron) produced significant signal‐intensity (SI) reduction over the right hemisphere and similar declines over the left. SI loss occurred first in the cortex and basal ganglia and later in the periventricular regions, along the midline, and in the thalamic zone. Sequential volume‐localized proton spectra acquired during transit of 0.02 mmol/kg iron showed substantial reduction in SI, slight asymmetric broadening, and no change in chemical shift of the water resonance. In rats with unilateral occlusion of the middle cerebral artery, peak reduction in ischemic brain SI was to 70% ± 9% of control, while normal brain SI was reduced to 18% ± 2% (P < .01), allowing distinction of the ischemic regions. The presence and location of injury were confirmed with diffusion‐weighted imaging and postmortem vital staining. These results demonstrate abnormal transit profiles in a rat model of regional brain ischemia. Evaluation of dynamic contrast delivery patterns may provide unique information in early brain ischemia.
Lumen definition in MR angiography
Authors: Lin Weili , Haacke E. Mark , Smith Alison S. 
Published: March 2007

AbstractFactors affecting blood vessel lumen definition for two‐dimensional and three‐dimensional inflow magnetic resonance (MR) imaging methods are considered. Vessel definition is affected (a) by the amount of dephasing of the blood in the vessels, both for uncompensated and velocity‐compensated gradients; (b) by the image reconstruction technique (normal Fourier reconstruction when asymmetric echoes are collected or a maximum‐intensity projection technique in postprocessing); (c) by loss of signal due to T2 de‐phasing; (d) by misregistration; (e) by vessel wall motion; and (f) by partial‐volume effects. The first two factors were found to dominate for resolution on the order of 1 mm3. To overcome these dephasing problems, the authors developed asymmetric echo, velocity‐compensated sequences with TEs as short as 4.8 msec. The data were then reconstructed with an iterative partial Fourier algorithm, enabling improved lumen definition to be obtained in phantoms and in vivo.
MR imaging—guided interstitial Nd:YAG laser phototherapy: Dosimetry study of acute tissue damage in an in vivo model
Authors: Anzai Yoshimi , Lufkin Robert B. , Castro Dan J. , Farahani Keyvan , Jabour Bradley A. , Layfield Lester J. , Udkoff Ranon , Hanafee William N. 
Published: March 2007

AbstractA dosimetry study of acute tissue damage induced by interstitial application of the neodymium‐yttrium‐aluminum‐garnet (Nd:YAG) laser was performed with magnetic resonance (MR) imaging. The MR appearance of the lesion was correlated with gross and histopathologic findings. Seventy‐six lesions were induced in rabbit muscle with laser power outputs of 5–20 W and exposure times of 20–600 seconds. MR imaging was performed immediately after laser exposure. T2‐weighted spin‐echo images clearly showed the acute thermal injuries caused by laser energy deposition and correlated best with histopathologic findings. These images showed three distinct layers, corresponding to central ablation, coagulative necrosis, and interstitial edema, respectively, in the pathologic findings. Lesion diameters measured on MR images showed a linear correlation with those in gross sections. Lesion volume increased not only with increasing total energy delivered but with increasing power output for a fixed total energy delivered. MR imaging is an accurate modality for dosimetry studies of laser‐induced acute lesions.