bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maintaining bioactivity of NGF for controlled release from PLGA using PEG
Authors: Johnson Philip J. , Skornia Stacy L. , Stabenfeldt Sarah E. , Willits Rebecca Kuntz 
Published: October 2007

AbstractThe goal of this work was to investigate methods to retain bioactivity of nerve growth factor (NGF) after encapsulation in poly(lactic‐co‐glycolic acid) (PLGA) discs for controlled release. Poly(ethylene glycol) (PEG) was chosen as a porogen not only to control the release rate of NGF but also because it has been used to help maintain bioactivity of molecules in organic solvents. NGF and PEG were encapsulated in PLGA via standard dissolution–evaporation techniques with methylene chloride as the solvent. Morita et al. (Pharm Res 2000; 17:1367–1373) indicated that colyophilization of PEG and bioactive factors before exposure to organic solvents increased the retention of bioactivity. Therefore, various PEG:NGF mass ratios were colyophilized before encapsulation within PLGA to examine retained activity of NGF. When PEG was not colyophilized before encapsulation, NGF activity was lost during the fabrication process. In contrast, colyophilization of PEG and NGF supported retention of NGF activity during the entire fabrication process. The amount of PEG encapsulated was the dominating factor in the rate of NGF release regardless of the fabrication method. These results demonstrate the usefulness of PEG in both acting as a porogen to modulate release and aiding in the retention of activity of NGF. This process may be extended to other methods to enhance activity of growth factors after exposure to organic solvents. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Development and characterization of a rabbit alveolar bone nonhealing defect model
Authors: Young Simon , Bashoura Alex G. , Borden Timothy , Baggett L. Scott , Jansen John A. , Wong Mark , Mikos Antonios G. 
Published: October 2007

AbstractThe aim of this study was to develop an easily accessible and reproducible, nonhealing alveolar bone defect in the rabbit mandible. Twenty‐four adult male New Zealand white rabbits underwent unilateral mandibular defect surgery. Two types of defect in the premolar/molar region were compared: (1) a 10‐mm “full thickness” cylindrical defect removing both cortical plates and the intervening trabecular bone and tooth roots; (2) a 10‐mm “partial thickness” cylindrical defect removing only the lateral bony cortex, trabecular bone, and tooth roots. Both types of defect were examined at 0, 8, and 16 weeks using histology and/or microcomputed tomography to determine the quality and quantity of bone formation. The partial thickness defect displayed significant bone fill at 8 weeks (86.9% ± 10.8%), and complete regeneration of bony contours and bridging by 16 weeks. In contrast, the full thickness defect was never able to bridge itself and displayed no significant difference in bone regeneration between the 8‐week (61.5% ± 3.7%) and 16‐week (55.1% ± 18.5%) time points. These results indicate that a nonhealing defect can be created with a 10‐mm bicortical cylindrical ostectomy placed in the premolar/molar region of the rabbit mandible, demonstrating the potential of this animal model as a test bed for mandibular biomaterials and tissue‐engineering constructs. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
β‐TCP microporosity decreases the viability and osteoblast differentiation of human bone marrow stromal cells
Authors: Isaac Juliane , Hornez Jean‐Christophe , Jian Ding , Descamps Michel , Hardouin Pierre , Magne David 
Published: October 2007

AbstractAssociation of osteoprogenitor cells to calcium phosphate ceramics is currently under intense investigation, for its considered ability to induce bone formation and therefore to allow the successful repair of large bone defects. However, if the first experimental and clinical studies provided promising results, lack of new bone formation has been reported in a large number of animal experiments. In this context and since it has been reported that in some conditions, calcium phosphate ceramic microstructure induces ectopic bone formation, we investigated the effects of ceramic microporosity on the behavior of osteoprogenitor cells for the development of hybrid materials. Human bone marrow stromal cells (BMSCs) were seeded on β‐tricalcium phosphate (TCP) ceramics with 0, 25, or 45% microporosity and cell adhesion, viability, and osteoblastic differentiation have been studied for three weeks. Cell counts, measurement of MTS conversion, and LDH activity indicated that microporosity decreased the viability of BMSCs in a time and rate‐dependent manner. In addition, microporosity inhibited osteoblastic differentiation as compared with nonmicroporous ceramics, as revealed by decreased alkaline phosphatase activity and osteocalcin secretion. Results of this in vitro study therefore highlight a negative role for β‐TCP microporosity in the behavior of human osteoprogenitor cells. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Synthesis, self‐association and chiroselectivity of isotopically labeled trianglamine macrocycles in the ion trap mass spectrometer
Authors: Kuhnert Nikolai , Le‐Gresley Adam , Nicolau Daniel C. , Lopez‐Periago Ana 
Published: October 2007

AbstractThe synthesis and self‐association of chiral isotopically labeled trianglamine macrocycles under electrospray mass spectrometer conditions in an ion trap are described. A moderate diastereoselectivity in the self‐association process was observed providing a synthetic model system for the investigation of chiral self‐association in the gas phase. The first non‐covalently bound dimer exclusively bonded through aromatic–aromatic interactions was observed in the gas phase. Evidence for self‐association in solution was observed by diffusion nuclear magnetic resonance spectroscopy. Copyright © 2007 John Wiley & Sons, Ltd.
Utilization of diffusion tensor tractography in combination with spatial normalization to assess involvement of the corticospinal tract in capsular/pericapsular stroke: Feasibility and clinical implications
Authors: Kunimatsu Akira , Itoh Daisuke , Nakata Yasuhiro , Kunimatsu Natsuko , Aoki Shigeki , Masutani Yoshitaka , Abe Osamu , Yoshida Mariko , Minami Manabu , Ohtomo Kuni 
Published: October 2007

AbstractPurposeTo investigate the feasibility of using spatial normalization in combination with diffusion tensor (DT) corticospinal tractography to assess corticospinal tract (CST) involvement in capsular or pericapsular stroke.Materials and MethodsCorticospinal tractograms were created and segmented out using DT imaging (DTI) data from 10 normal volunteers. After spatial normalization was achieved with statistical parametric mapping (SPM), the whole ensemble of tractograms was used as a map of the CST. This was overlaid on the infarction site, which had also been spatially normalized from isotropic diffusion‐weighted (DW) images of 14 patients with small symptomatic capsular or pericapsular infarction. We evaluated the extent of CST involvement within the infarction site. Differences were sought in relation to recovery of muscle strength.ResultsThe CST was engulfed by the infarction in all patients. Muscle strength recovery occurred in 10 of the 14 patients. The extent of cross‐sectional and longitudinal involvement in the infarction site was related to motor recovery (P = 0.041).ConclusionAn evaluation of the involvement of the CST in cases of capsular or pericapsular infarction utilizing DT fiber tractography in combination with spatial normalization was found to be feasible as it clearly visualized the extent of CST involvement consistent with the symptom. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
MRI evaluation of microvascular obstruction in experimental reperfused acute myocardial infarction using a T1 and T2 preparation pulse sequence
Authors: Yang Yuesong , Foltz Warren D. , Graham John J. , Detsky Jay S. , Dick Alexander J. , Wright Graham A. 
Published: October 2007

AbstractPurposeTo investigate a T1 and T2 preparation pulse sequence to evaluate microvascular obstruction (MO) in a porcine model of reperfused acute myocardial infarction (AMI).Materials and MethodsA total of 14 pigs with reperfused AMI underwent MRI examinations at baseline and three to four hours after reperfusion. MRI scans included a left ventricular functional study, T1 and T2 measurement on a 1.5T MRI system. At reperfusion, first‐pass myocardial perfusion (FPMP) images were obtained after bolus injection of gadopentetate dimeglumine followed by an intravenous drip. Delayed contrast‐enhanced MRI (DE‐MRI) and T1 measurements were performed 30 and 45 minutes, respectively, after the bolus, during a constant infusion of gadopentetate dimeglumine.ResultsIn 11 pigs MO was hypoenhanced in FPMP and DE‐MRI. In later T1 preparation difference images postcontrast, MO was hyperenhanced while delayed hyperenhanced (DHE) regions appeared dark. MO areas on DE‐MRI and T1 images were comparable. T1 reduction (%) postcontrast in MO was small compared to measurements from DHE regions (P < 0.0001) and similar to those from control segments (P = 0.66). Precontrast T1 and T2 values at reperfusion from MO and DHE regions were larger than in control regions.ConclusionUsing T1 preparation under a constant gadopentetate dimeglumine (Gd‐DTPA) infusion, delayed imaging at 30 to 45 minutes demonstrates MO as a positive contrast with larger T1 values. Elevated T1 and T2 values in MO precontrast may also help to differentiate them from both control and DHE regions. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Comparison of flow patterns in ascending aortic aneurysms and volunteers using four‐dimensional magnetic resonance velocity mapping
Authors: Hope Thomas A. , Markl Michael , Wigström Lars , Alley Marcus T. , Miller D. Craig , Herfkens Robert J. 
Published: October 2007

AbstractPurposeTo determine the difference in flow patterns between healthy volunteers and ascending aortic aneurysm patients using time‐resolved three‐dimensional (3D) phase contrast magnetic resonance velocity (4D‐flow) profiling.Materials and Methods4D‐flow was performed on 19 healthy volunteers and 13 patients with ascending aortic aneurysms. Vector fields placed on 2D planes were visually graded to analyze helical and retrograde flow patterns along the aortic arch. Quantitative analysis of the pulsatile flow was carried out on manually segmented planes.ResultsIn volunteers, flow progressed as follows: an initial jet of blood skewed toward the anterior right wall of the ascending aorta is reflected posterolaterally toward the inner curvature creating opposing helices, a right‐handed helix along the left wall and a left‐handed helix along the right wall; retrograde flow occurred in all volunteers along the inner curvature between the location of the two helices. In the aneurysm patients, the helices were larger; retrograde flow occurred earlier and lasted longer. The average velocity decreased between the ascending aorta and the transverse aorta in volunteers (47.9 mm/second decrease, P = 0.023), while in aneurysm patients the velocity increased (145 mm/second increase, P < 0.001).ConclusionDilation of the ascending aorta skews normal flow in the ascending aorta, changing retrograde and helical flow patterns. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Quantitative in vivo proton MR spectroscopic evaluation of the irradiated rat brain
Authors: Atwood Todd , Robbins Mike E. , Zhu Jian‐Ming 
Published: October 2007

AbstractPurposeTo investigate if in vivo localized proton magnetic resonance spectroscopy (MRS) can detect putative metabolic changes in the irradiated rat brain and quantitatively measure brain metabolite changes in this model.Materials and MethodsA total of 20 adult male Fischer 344 rats were exposed to a fractionated regimen of whole brain irradiation (WBI) (total 45 Gy, given as five Gy fractions, twice per week for 4.5 weeks); 10 control rats received sham irradiation. A total of 52 weeks after WBI, all animals were subjected to high‐resolution MRI and in vivo proton MRS to determine structural and brain metabolite changes. Brain metabolites were measured by using single‐voxel MRS. Quantitative analysis of detectable metabolites was performed by using the spectral analysis method, LCModel.ResultsSignificant differences in brain metabolite concentrations were detected in rat brains irradiated with a clinically relevant fractionated radiotherapy regimen in 52 weeks, in comparison to age‐matched sham‐irradiated rats.ConclusionThese findings indicate that quantitative in vivo MRS may serve as a sensitive imaging tool to noninvasively detect neurochemical changes in the irradiated brain. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Real‐time MR imaging of myocardial regional function using strain‐encoding (SENC) with tissue through‐plane motion tracking
Authors: Ibrahim El‐Sayed H. , Stuber Matthias , Fahmy Ahmed S. , Abd‐Elmoniem Khaled Z. , Sasano Tetsuo , Abraham M. Roselle , Osman Nael F. 
Published: October 2007

AbstractPurposeTo implement real‐time myocardial strain‐encoding (SENC) imaging in combination with tracking the tissue displacement in the through‐plane direction.Materials and MethodsSENC imaging was combined with the slice‐following technique by implementing three‐dimensional (3D) selective excitation. Certain adjustments were implemented to reduce scan time to one heartbeat. A total of 10 volunteers and five pigs were scanned on a 3T MRI scanner. Spatial modulation of magnetization (SPAMM)‐tagged images were acquired on planes orthogonal to the SENC planes for comparison. Myocardial infarction (MI) was induced in two pigs and the resulting SENC images were compared to standard delayed‐enhancement (DE) images.ResultsThe strain values computed from SENC imaging with slice‐following showed significant difference from those acquired without slice‐following, especially during systole (P < 0.01). The strain curves computed from the SENC images with and without slice‐following were similar to those computed from the orthogonal SPAMM images, with and without, respectively, tracking the tag line displacement in the strain direction. The resulting SENC images showed good agreement with the DE images in identifying MI in infarcted pigs.ConclusionCorrection of through‐plane motion in real‐time cardiac functional imaging is feasible using slice‐following. The strain measurements are more accurate than conventional SENC measurements in humans and animals, as validated with conventional MRI tagging. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Multiparametric differentiation of posterior fossa tumors in children using diffusion‐weighted imaging and short echo‐time 1H‐MR spectroscopy
Authors: Schneider J.F. , Confort‐Gouny S. , Viola A. , Le Fur Y. , Viout P. , Bennathan M. , Chapon F. , Figarella‐Branger D. , Cozzone P. , Girard N. 
Published: October 2007

AbstractPurposeTo assess the combined value of diffusion‐weighted imaging (DWI) and proton magnetic resonance spectroscopy (1H‐MRS) in differentiating medulloblastoma, ependymoma, pilocytic astrocytoma, and infiltrating glioma in a pediatric population.Materials and MethodsA total of 17 children with untreated posterior fossa tumors (seven medulloblastoma, four infiltrating glioma, two ependymoma, and four pilocytic astrocytoma), were investigated with conventional MRI, DWI, and MRS using a single‐voxel technique. Within the nonnecrotic tumor core, apparent diffusion coefficient (ADC) values using a standardized region of interest (ROI) were retrieved. Quantification of water signal and analysis of metabolite signals from MRS measurements in the same tumorous area were reviewed using multivariant linear discriminant analysis.ResultsCombination of ADC values and metabolites, which were normalized using water as an internal standard, allowed discrimination between the four tumor groups with a likelihood below 1 × 10–9. Positive predictive value was 1 in all cases. Tumors could not be discriminated when using metabolite ratios or ADC values alone, nor could they be differentiated using creatine (Cr) as an internal reference even in combination with ADC values.ConclusionLinear discriminant analysis using DWI and MRS using water as internal reference, fully discriminates the four most frequent posterior fossa tumors in children. J. Magn. Reson. Imaging. © 2007 Wiley‐Liss, Inc.
MRI of ischemic stroke in canines: Applications for monitoring intraarterial thrombolysis
Authors: Harris Ashley D. , Kosior Jayme C. , Ryder Ronda C. , Andersen Linda B. , Hu William Y. , Hudon Mark , Morrish William H. , Sevick Robert J. , Wong John , Frayne Richard 
Published: October 2007

AbstractPurposeTo describe a canine embolic stroke model that is appropriate for endovascular procedure evaluations and develop local cerebral blood flow (CBF) maps to monitor the progression of stroke and thrombolysis. In the future, MR may displace X‐ray imaging in some endovascular procedures, such as intraarterial (IA) thrombolysis for stroke therapy, due to increased monitoring capabilities. For MR to attain its full potential in endovascular therapy, the development of appropriate disease models and monitoring techniques is essential.Materials and MethodsThe canine stroke model uses an injection of autologous clot to produce ischemic and infarcted tissue and produces a range of stroke severities within the anterior cerebral circulation. Local CBF maps were formed by using the catheter that would be in place to deliver the thrombolytic agent for treatment to deliver the gadolinium‐based contrast agent for perfusion imaging.ResultsAfter the injection of clot, changes on imaging were consistent with the progression of ischemic stroke. Local CBF maps showed perfusion changes with stroke progression and treatment.ConclusionWe successfully demonstrate the progression of ischemic stroke in the canine to mimic the progression of human stroke. CBF maps to show local perfusion characteristics show great potential in the evaluation of stroke therapy. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Improved tumor vascular function following high‐dose epidermal growth factor receptor tyrosine kinase inhibitor therapy
Authors: Moasser Mark M. , Wilmes Lisa J. , Wong Ching Hang , Aliu Sheye , Li Ka‐Loh , Wang Donghui , Hom Yun Kit , Hann Byron , Hylton Nola M. 
Published: October 2007

AbstractPurposeTo determine if inhibitors of the human growth factor receptor (HER) family can be used to enhance tumor vascular permeability and perfusion and optimize the efficacy of cytotoxic chemotherapeutics. Poor tumor vascular function limits the delivery and efficacy of cancer chemotherapeutics and HER family tyrosine kinases mediate tumor‐endothelial signaling in both of these compartments.Materials and MethodsBT474 human breast cancer tumors were established in mice and the biologic effects of the HER tyrosine kinase inhibitor (TKI) gefitinib on tumor vascular function was determined by dynamic contrast‐enhanced MRI (DCE‐MRI), and on tumor vascular architecture and perfusion by immunofluorescence microscopy.ResultsA brief dose of gefitinib enhances the antitumor activity of paclitaxel in vivo but not in cell culture, suggesting that its chemoenhancing activity involves the in vivo microenvironment. A brief high dose of gefitinib induces a decrease in endothelial transfer constant (Kps) and a concomitant increase in tumor fractional plasma volume (fPV). These changes are accompanied by a rapid reduction in tumor volume, likely due to decreased tumor edema, and modestly improved tumor vascular architecture and perfusion on microscopy.ConclusionThese data suggest that HER family TKIs have the potential to optimize the tumor microenvironment for delivery of cytotoxic chemotherapeutics. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
Black‐blood imaging of the human heart using rapid stimulated echo acquisition mode (STEAM) MRI
Authors: Karaus Alexander , Merboldt Klaus‐Dietmar , Graessner Joachim , Frahm Jens 
Published: October 2007

AbstractPurposeTo develop a rapid stimulated echo acquisition mode (STEAM) MRI technique for “black‐blood” imaging of the human heart that overcomes the single‐slice limitation and partially compromised blood suppression associated with double inversion‐recovery techniques.Materials and MethodsBlack‐blood multislice images of the heart along anatomic orientations and triggered to end diastole were obtained from healthy human subjects at 3T using rapid STEAM MRI sequences with five‐eighths partial Fourier encoding and variable flip angles. Single‐shot STEAM images at 2.5 × 2.5 mm2 in‐plane resolution and 6‐mm section thickness were recorded in 230 msec from individual heartbeats. Improved signal‐to‐noise ratio (SNR) and higher spatial resolution of 2.0 × 2.0 mm2 and 1.5 × 1.5 mm2 were achieved by segmented multishot STEAM MRI with interleaved k‐space acquisitions (160 msec each) from several heartbeats. In a single breathhold covering 18 heartbeats selected applications employed either three segments with six sections or six segments with three sections.ResultsBecause stimulated echoes (STEs) dephase signals from moving spins, rapid STEAM images are free from blood signal contamination. The method offers a flexible tradeoff between spatial resolution, imaging speed (i.e., number of segments), and volume coverage (i.e., number of sections).ConclusionRapid STEAM MRI of the heart emerges as a simple technique for multislice imaging of the myocardial wall with efficient flow suppression. J. Magn. Reson. Imaging 2007. © 2007 Wiley‐Liss, Inc.
New designer drugs N‐(1‐phenylcyclohexyl)‐2‐ethoxyethanamine (PCEEA) and N‐(1‐phenylcyclohexyl)‐2‐methoxyethanamine (PCMEA): Studies on their metabolism and toxicological detection in rat urine using gas chromatographic/mass spectrometric techniques
Authors: Sauer Christoph , Peters Frank T. , Staack Roland F. , Fritschi Giselher , Maurer Hans H. 
Published: October 2007

AbstractStudies are described on the metabolism and the toxicological detection of the phencyclidine‐derived designer drugs N‐(1‐phenylcyclohexyl)‐2‐ethoxyethanamine (PCEEA) and N‐(1‐phenylcyclohexyl)‐2‐methoxyethanamine (PCMEA) in rat urine using gas chromatographic/mass spectrometric (GC/MS) techniques. The identified metabolites indicated that PCEEA and PCMEA were transformed to the same metabolites by N‐dealkylation and O‐dealkylation partially followed by oxidation of the resulting alcohol to the respective carboxylic acid and hydroxylation of the cyclohexyl ring at different positions and combinations of those. Finally, aromatic hydroxylation of the O‐dealkylated metabolites was partially followed by hydroxylation of the cyclohexyl ring at different positions. All metabolites were partially excreted in conjugated form. The authors' systematic toxicological analysis (STA) procedure using full‐scan GC/MS after acid hydrolysis, liquid–liquid extraction and microwave‐assisted acetylation allowed the detection of an intake of a common drug users' dose both of PCEEA and PCMEA in rat urine. Assuming similar metabolism in humans, the STA should be suitable for proof of an intake of PCEEA and PCMEA in human urine, although their differentiation is not possible due to common metabolites. Copyright © 2007 John Wiley & Sons, Ltd.