bluuebunny/crossref_metadata_2025_split huggingface dataset:
Associations between family history of Parkinson's disease and dementia and risk of dementia in Parkinson's disease: A community‐based, longitudinal study
Authors: Kurz Martin Wilhelm , Larsen Jan Petter , Kvaloy Jan Terje , Aarsland Dag 
Published: October 2006

AbstractDementia is common in patients with Parkinson's disease (PDD). The etiology of PDD is still unclear, but exciting advances have been made in discovering pathogenetic components in Parkinson's disease (PD), implicating the role of genetic factors. It is, however, still controversial whether genetic factors also contribute to the development of dementia in PD. Thus, we investigated the association between development of dementia and a positive family history of PD or dementia in a community‐based study of PD in Rogaland County, Norway (n = 219). The patients were followed prospectively with neurological and neuropsychological assessments. Dementia was more common in patients with a strong family association of PD (first‐degree relatives > second‐degree relatives > no family history; P < 0.05). However, time to dementia did not differ between the two groups. No associations between dementia in PD and familial occurrence of dementia could be shown. Further studies with larger samples are needed to explore a possible relationship between a family history of PD and development of dementia in PD and its potential pathogenetic mechanisms. © 2006 Movement Disorder Society
Chemodosimetry of in vivo tumor liposomal drug concentration using MRI
Authors: Viglianti Benjamin L. , Ponce Ana M. , Michelich Charles R. , Yu Daohai , Abraham Sheela A. , Sanders Linda , Yarmolenko Pavel S. , Schroeder Thies , MacFall James R. , Barboriak Daniel P. , Colvin O. Michael , Bally Marcel B. , Dewhirst Mark W. 
Published: October 2006

AbstractEffective cancer chemotherapy depends on the delivery of therapeutic drugs to cancer cells at cytotoxic concentrations. However, physiologic barriers, such as variable vessel permeability, high interstitial fluid pressure, and heterogeneous perfusion, make it difficult to achieve that goal. Efforts to improve drug delivery have been limited by the lack of noninvasive tools to evaluate intratumoral drug concentration and distribution. Here we demonstrate that tumor drug concentration can be measured in vivo using T1‐weighted MRI, following systemic administration of liposomes containing both drug (doxorubicin (DOX)) and contrast agent (manganese (Mn)). Mn and DOX concentrations were calculated using T1 relaxation times and Mn:DOX loading ratios, as previously described. Two independent validations by high‐performance liquid chromatography (HPLC) and histologic fluorescence in a rat fibrosarcoma (FSA) model indicate a concordant linear relationship between DOX concentrations determined using T1 and those measured invasively. This method of imaging exhibits potential for real‐time evaluation of chemotherapeutic protocols and prediction of tumor response on an individual patient basis. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Microvessel density estimation in the human brain by means of dynamic contrast‐enhanced echo‐planar imaging
Authors: Jensen Jens H. , Lu Hanzhang , Inglese Matilde 
Published: October 2006

AbstractAnimal studies have shown that in vivo estimates of microvessel density in the brain may be obtained from an MRI‐measurable index (Q) provided that a sufficiently high dose of an intravascular paramagnetic contrast agent is employed. Q is determined from the shifts in the transverse relaxation rates induced by the contrast agent, and a high dose is required for the validity of analytic expressions relating Q to the microvessel density. However, the steady‐state imaging techniques used in these prior investigations are not appropriate for humans, as the required contrast agent dose is too large. Here results of a pilot study with three subjects are reported. The results suggest that reliable Q measurements can be performed in the human brain at 1.5 T by using an interleaved spin‐echo (SE)/gradient‐echo (GE) echo‐planar imaging (EPI) sequence and a bolus injection of a triple dose of Gd‐DTPA. Lower‐ and upper‐bound estimates for the microvessel density were derived from the Q‐values, and were found to be in reasonable accord with previously cited values determined by histology. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
T2 measurement and quantification of glutamate in human brain in vivo
Authors: Choi Changho , Coupland Nicholas J. , Bhardwaj Paramjit P. , Kalra Sanjay , Casault Colin A. , Reid Kim , Allen Peter S. 
Published: October 2006

AbstractThe proton NMR transverse relaxation time T2 of glutamate (Glu) in human brain was measured by means of spectrally selective refocusing at 3.0 T in vivo. An 81.4‐ms‐long dual‐band Gaussian 180° RF pulse, designed for refocusing at 2.35 and 3.03 ppm, was employed within point‐resolved spectroscopy (PRESS) to generate the Glu C4‐proton target multiplet and the total creatine (tCr) singlet. Six optimal echo times (TEs) between 128 and 380 ms were selected from numerical analysis of the filtering performance for effective detection of the Glu signal with minimal contamination from glutamine (Gln), N‐acetylaspartate (NAA), and glutathione (GSH). The magnetization of Glu and tCr was extracted from spectral fitting of experimental and calculated spectra. Apparent T2 values of Glu and tCr were estimated as 201 ± 18 and 164 ± 12 ms for the medial prefrontal (PF) cortex, and 198 ± 22 and 169 ± 15 ms (mean ± SD, N = 5) for the left frontal (LF) cortex, respectively. With water segmentation data, the magnetization values of Glu and tCr of the two adjacent voxels, calculated from the T2 values and spectra following the thermal equilibrium magnetization, were combined to give the Glu and tCr concentrations as 10.37 ± 1.06 and 8.87 ± 0.56 mM for gray matter (GM), and 5.06 ± 0.57 and 5.16 ± 0.45 mM (mean ± SD, N = 5) for white matter (WM), respectively. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Three‐dimensional prepolarized magnetic resonance imaging using rapid acquisition with relaxation enhancement
Authors: Matter Nathaniel I. , Scott Greig C. , Venook Ross D. , Ungersma Sharon E. , Grafendorfer Thomas , Macovski Albert , Conolly Steven M. 
Published: October 2006

AbstractPrepolarized MRI (PMRI) with pulsed electromagnets has the potential to produce diagnostic quality 0.5‐ to 1.0‐T images with significantly reduced cost, susceptibility artifacts, specific absorption rate, and gradient noise. In PMRI, the main magnetic field cycles between a high field (Bp) to polarize the sample and a homogeneous, low field (B0) for data acquisition. This architecture combines the higher SNR of the polarizing field with the imaging benefits of the lower field. However, PMRI can only achieve high SNR efficiency for volumetric imaging with 3D rapid imaging techniques, such as rapid acquisition with relaxation enhancement (RARE) (FSE, TSE), because slice‐interleaved acquisition and longitudinal magnetization storage are both inefficient in PMRI. This paper demonstrates the use of three techniques necessary to achieve efficient, artifact‐free RARE in PMRI: quadratic nulling of concomitant gradient fields, electromotive force cancelation during field ramping, and phase compensation of CPMG echo trains. This paper also demonstrates the use of 3D RARE in PMRI to achieve standard T1 and fat‐suppressed T2 contrast in phantoms and in vivo wrists. These images show strong potential for future clinical application of PMRI to extremity musculoskeletal imaging and peripheral angiography. Magn Reason Med, 2006. © 2006 Wiley‐Liss.Inc.
Risk factors for extraocular relapse following enucleation after failure of chemoreduction in retinoblastoma
Authors: Chantada Guillermo L. , Dunkel Ira J. , Antoneli Celia B.G. , de Dávila María T.G. , Arias Victor , Beaverson Katherine , Fandiño Adriana C. , Chojniak Martha , Abramson David H. 
Published: October 2006

AbstractObjectiveTo assess the outcome and determine risk factors for extraocular relapse in patients with retinoblastoma who had been enucleated after failure of chemoreduction.MethodsRetrospective study (1995–2002) at three institutions. Pathological risk factors (PRF) were defined as invasion of the anterior segment, choroid, post‐laminar optic nerve, subarachnoid space, or sclera according to the local pathology report. Extraocular relapse was defined as an event.ResultsOne hundred twenty‐two patients were included (17 had bilateral enucleation). Chemoreduction included vincristine, carboplatin, and etoposide (n = 80, 65.6%), vincristine, and carboplatin (n = 17, 13.9%), or carboplatin (n = 25, 20.5%). Thirty‐five also received external beam radiotherapy (28.7%). PRF included: 39 with choroidal involvement, 9 with anterior segment, 9 with scleral, and 2 with post‐laminar optic nerve with subarachnoid invasion. Adjuvant chemotherapy was given to eight patients (6.5%) because of scleral invasion. Four patients had an extraocular relapse after enucleation, two of whom survive after intensive treatment including stem cell rescue. Five‐year probability of event‐free survival is 0.96. Only scleral invasion and bilateral enucleation were significantly associated with extraocular relapse.ConclusionsThe risk of extraocular relapse is low after enucleation following failure of chemoreduction. Patients who underwent bilateral enucleation and those with scleral invasion are at higher risk of extraocular relapse. Pediatr Blood Cancer 2007;49:256–260. © 2006 Wiley‐Liss, Inc.
Novel approach for α‐helical topology prediction in globular proteins: Generation of interhelical restraints
Authors: McAllister S. R. , Mickus B. E. , Klepeis J. L. , Floudas C. A. 
Published: October 2006

AbstractThe protein folding problem represents one of the most challenging problems in computational biology. Distance constraints and topology predictions can be highly useful for the folding problem in reducing the conformational space that must be searched by deterministic algorithms to find a protein structure of minimum conformational energy. We present a novel optimization framework for predicting topological contacts and generating interhelical distance restraints between hydrophobic residues in α‐helical globular proteins. It should be emphasized that since the model does not make assumptions about the form of the helices, it is applicable to all α‐helical proteins, including helices with kinks and irregular helices. This model aims at enhancing the ASTRO‐FOLD protein folding approach of Klepeis and Floudas (Journal of Computational Chemistry 2003;24:191–208), which finds the structure of global minimum conformational energy via a constrained nonlinear optimization problem. The proposed topology prediction model was evaluated on 26 α‐helical proteins ranging from 2 to 8 helices and 35 to 159 residues, and the best identified average interhelical distances corresponding to the predicted contacts fell below 11 Å in all 26 of these systems. Given the positive results of applying the model to several protein systems, the importance of interhelical hydrophobic‐to‐hydrophobic contacts in determining the folding of α‐helical globular proteins is highlighted. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Structural comparison of oxidized and reduced FKBP13 from Arabidopsis thaliana
Authors: Gopalan Gayathri , He Zengyong , Battaile Kevin P. , Luan Sheng , Swaminathan Kunchithapadam 
Published: October 2006

AbstractAtFKBP13, an immunophilin in the chloroplast thylakoid lumen, participates in redox‐regulatory processes via a pair of conserved disulfide bonds that are present at the N‐ and C‐termini of the protein. Characterization of this protein by structural and biochemical analysis has revealed a novel mechanism of redox regulation in the thylakoid lumen. The protein is active in its oxidized form but is inactivated after reduction by the thioredoxin system. This is in sharp contrast with the regulation of biosynthetic enzymes in the stroma of the chloroplast, where reduction of enzymes by thioredoxin activates their function. To understand how the reduced form of AtFKBP13 is stabilized and how reduction of the cysteine residues affects the molecular properties of the enzyme, we determined the crystal structure of reduced AtFKBP13 at 1.88 Å. Comparison of the reduced structure and the oxidized form that we published earlier shows rearrangements in redox site regions, readjustments of hydrogen‐bonding interactions and the secondary structure of the active site residues 50–53, and reduced accessibility of the catalytic residues involved in the peptidyl proline isomerase (PPIase) activity of this enzyme. We propose that redox‐linked changes in the secondary structure of the PPIase domain are responsible for significant functional differences in this protein in the reduced and oxidized states. Proteins 2006. © 2006 Wiley‐Liss, Inc.
n‐Type doping of diamond
Authors: Koizumi Satoshi , Suzuki Mariko 
Published: October 2006

Abstractn‐Type diamond formation is one of the most important issues for the electronic application of diamond. Phosphorus is the best n‐type dopant candidate at the moment. We have succeeded in growing high‐quality phosphorus‐doped diamond thin films on {111} diamond substrates. Although the ionization energy of the phosphorus donor is large (0.57 eV), the n‐type conductivity is clearly observed by Hall measurements. The Hall mobility is as high as 660 cm2/(V s) at room temperature. In this paper, the current status of n‐type diamond research is mentioned with focus mainly on the growth of high‐mobility n‐type diamond and its electrical properties. The Hall measurements performed over a wide temperature range give detailed information about the nature of the n‐type conductivity. Current–voltage and capacitance–voltage measurements of a Schottky diode formed by nickel contacts on an n‐type diamond layer show unique characteristics of semiconducting diamond. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Emission properties from dense exciton gases in diamond
Authors: Okushi Hideyo , Watanabe Hideyuki , Yamasaki Satoshi , Kanno Shokichi 
Published: October 2006

AbstractA systematic study of cathodoluminescence (CL) emission arising from free exciton recombination in diamond is given. CL spectra of free exciton emission from diamond under high excitation conditions were used to characterize properties of ultradense exciton gases at quasi‐thermal equilibrium. Theoretical spectra of excitonic emission from diamond were calculated based on Bose–Einstein (BE) statistics, taking into account collision of excitons in an indirect semiconductor like diamond. The calculated spectra agreed well with the observed spectra over a wide temperature range for high‐quality homoepitaxial chemical vapor deposition diamond thin films. The analysis showed that a high density of excitons of over 1018 cm−3 could be achieved under thermodynamic quasi‐equilibrium by continuous electron beam excitation, at which BE condensation can be expected at low temperature. These results indicate that diamond is a perfect material for the generation and detection of BE condensation which is the most characteristic features of BE statistics. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The transformation of open picotubes to a closed molecular configuration
Authors: Schaman Christoph , Pfeiffer Rudolf , Zólyomi Viktor , Kuzmany Hans , Ajami Daniel , Herges Rainer , Dubay Orest , Sloan Jeremy 
Published: October 2006

AbstractStarting with the open picotube, we studied the interaction of the picotube with carbon nanotubes. The picotube is easily produced at low cost, and therefore an ideal candidate for filling CNTs. The observed spectra are in good agreement with the spectra predicted by Gaussian'03 for the closed picotube. The stability of the molecule in two different environments, the inside and the outside of the nanotubes, were investigated in local density approximation and inter‐molecular Hückel calculations. We conclude that the closed picotube was formed, and is located on the outside of bundles of nanotubes. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and electronic properties of Ptn (n = 3, 7, 13) clusters on metallic single wall carbon nanotube
Authors: Cuong Nguyen Thanh , Chi Dam Hieu , Kim Yong‐Tae , Mitani Tadaoki 
Published: October 2006

AbstractA systematic study of Ptn (n = 3, 5, 7) clusters adsorbed on the metallic (5, 5) single wall carbon nanotube was carried out using theoretical calculations within Density Functional Theory. The geometrical and electronic structure and interaction between the Pt clusters and the single wall carbon nanotube were investigated. The bridge adsorption sites on the outer wall of the carbon nanotube are found favorable for Pt atom. We found that the average C–Pt and Pt–Pt bond length, binding energy, and the amount of charge transfers from the Pt cluster toward the nanotube increase with the size of cluster. The calculated density‐of‐states suggest a mixing of ionic and covalent character for the binding nature of this system. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The study of the interaction of human mesenchymal stem cells and monocytes/macrophages with single‐walled carbon nanotube films
Authors: Kalbacova M. , Kalbac M. , Dunsch L. , Kataura H. , Hempel U. 
Published: October 2006

AbstractThe influence of single‐walled carbon nanotube (SWCNT) films on two different human cell types was investigated: primary mesenchymal stem cells (MSC) and the monocytes/macrophages cell line THP‐1, the focus being on the metabolic activity of these cells. The SWCNT were free of impurity as was confirmed by Raman and VIS‐NIR spectroscopy. No surfactant was used to minimize the effect of other agents on the behavior of the cells. The results obtained on SWCNT films were compared to those measured on carbon fibers (CF). The metabolic activity of the investigated cell types cultured on SWCNT film was only slightly reduced (about 20%), while carbon fibers led to a much stronger decrease (about 40%). The reaction of the cells depended on the cell number, with more cells showing less metabolic inhibition. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis of single‐walled carbon nanotubes with the laser vaporization method: Ex situ and in situ measurements
Authors: Cau M. , Dorval N. , Attal‐Trétout B. , Cochon J. L. , Pigache D. , Loiseau A. , Arutyunyan N. R. , Obraztsova E. D. , Krüger V. , Tsurikov M. 
Published: October 2006

AbstractIn situ measurements were executed in the continuous wave CO2‐laser vaporization synthesis of single‐walled carbon nanotubes (SWCNTs). The results were compared with the findings of the ex situ analysis of the product. Different catalysts (Co, Ni, Co/Ni, Ni/Y and Co/Y) were used and the temperature of the target surface (T s) changed to compare the efficiency of the synthesis process. Our main results are related to the SWCNTs diameter which is depending on T s and on the catalysts nature. The targets containing Y with Co or Ni atoms produce more and larger SWCNTs than Co/Ni targets. The SWCNTs' diameter is seen to increase with T s. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
NMR study of spin excitations in carbon nanotubes
Authors: Singer P. M. , Wzietek P. , Alloul H. , Simon F. , Kuzmany H. 
Published: October 2006

AbstractThe spin dynamics of 13C isotope enriched inner‐walls in double‐wall carbon nanotubes (DWCNT) has been studied using 13C nuclear magnetic resonance (NMR). Contrary to expectations, the spin–lattice relaxation time (T 1) has the same temperature (T) and magnetic field (H) dependence for most of the inner‐wall nanotubes detected by NMR. In the high temperature regime (T ≳ 150 K), we find that the T and H dependence of 1/T 1T is consistent with a 1D metallic chain. For T ≲ 150 K the data clearly indicates the formation of a gap in the spin excitation spectrum, where the gap value 2Δ ≃ 40 K (≡ 3.7 meV) is H independent. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effect of molecular oxygen on the thermal conductance of multi‐walled nanotubes – a preliminary investigation
Authors: Brown E. , Hao L. , Gallop J. C. , Macfarlane J. C. , Josephs‐Franks P. W. , Cohen L. F. 
Published: October 2006

AbstractWhilst the effect of oxygen adsorption on the electrical properties of carbon nanotubes has been investigated extensively, little is known about how oxygen changes the thermal properties of nanotubes.Here we present a preliminary investigation on the effect of molecular oxygen on the electrical and thermal conductance of multi‐walled nanotubes (MWNTs) measured simultaneously.The nanotubes were placed in a vacuum chamber (pressures <1 × 10–5 mbar) for a prolonged period of time (>7 days) and continuously heated above 100 °C to ensure oxygen desorption. Then pure oxygen was introduced in the chamber using a needle valve (the pressure in the chamber was always <3 × 10–4 mbar) and the heating of the nanotube was stopped to allow oxygen adsorption.Thermal and electrical conductance measurements were taken simultaneously on the nanotubes when degassed and in the presence of oxygen.The thermal conductance of the nanotubes increased by a maximum of about 20% upon addition of oxygen. The percentage increase was initially linearly dependent on the amount of oxygen added then at oxygen pressures >1 × 10−4 mbar saturation of the effect was observed.The reasons for these changes are proposed to be: (i) oxygen adsorption caused a change in the nanotubes' phonon modes; (ii) the presence of oxygen molecules facilitated the inter‐shell transfer of heat in the nanotube. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman intensities of the first optical transitions in carbon nanotubes
Authors: Telg H. , Maultzsch J. , Reich S. , Hennrich F. , Thomsen C. 
Published: October 2006

AbstractWe performed resonant Raman spectroscopy on the lowest optical transition E S11 of separated single‐walled carbon nanotubes by studying the radial‐breathing mode (RBM) spectra for excitation energies between 1.15 and 1.48 eV. We were able to extend the experimental Kataura plot to these energies by adding the E S11 transition energies of 11 nanotube chiralities. We discuss also the relative Raman intensities; they are more similar for different family index ν than those of the corresponding transitions of the E S22 [1]. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐density selective excitation effect on excitons in semimagnetic semiconductor CdMnTe
Authors: Katayama K. , Miyajima K. , Ashida M. , Itoh T. 
Published: October 2006

AbstractMany body effects among electron–hole pairs and exchange interaction of spins between electron/hole and Mn2+ ions have been investigated in a semimagnetic semiconductor of CdMnTe under the selective excitation of high‐density localized excitons with use of a picosecond pulse laser. A new nonlinear luminescence band (X band) has been found on the high‐energy side of conventional exciton magnetic polaron band and its peak energy shows a pronounced red shift with the increase of excitation power and/or with the application of magnetic field. Time‐resolved luminescence without magnetic field has revealed the characteristic behaviour of the X band with a longer rise time for the higher energy side. However, this tendency disappears with the application of magnetic field. As the origin of the X band, we propose the high‐density spin‐polarized electron–hole pairs interacting with microscopic Mn2+‐ion spins aligned through the exchange interaction. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)