bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of ultrafast half‐Fourier single‐shot turbo spin‐echo sequence with turbo spin‐echo sequences for T2‐weighted imaging of the female pelvis
Authors: Yamashita Yasuyuki , Tang Yi , Abe Yasuko , Mitsuzaki Katsuhiko , Takahashi Matsumasa
Published: March 2007

So that we might evaluate the ultrafast half‐Fourier single‐shot turbo spin‐echo (HASTE) sequence in T2‐weighted MRI of the female pelvis and compare it with the turbo spin‐echo (TSE) sequence, we prospectively studied 60 consecutive females with suspected abnormalities of the pelvis. For all MR examinations, we used a 1.5‐T superconductive magnet with a phased array coil. The HASTE sequence was applied with TR/effective TE/echo train = ∞/90/64 and a 128 × 256 matri× (acquisition time: .3 sec/slice), conventional TSE imaging with 3,400 to 5,000/132/15 and a 128 × 256 matri× (mean acquisition time: 2 min 4 sec), and high‐resolution TSE imaging with 3,400 to 5,000/132/15 and a 300 × 512 matri× (6 min 4 sec). Although the lesion conspicuity for the HASTE sequence was less than that for the high‐resolution TSE sequences, artifacts (including ghosting, bowel motion, susceptibility difference, and chemical shift) were negligible on HASTE images of all patients. The lesion conspicuity for the HASTE sequence was significantly better than for the conventional TSE sequence. In spite of the very short acquisition time, the subjective scoring of the overall image quality for the HASTE sequence was significantly higher than for the conventional TSE sequence (P < .01) and were slightly lower than for the high‐resolution TSE sequence. Compared with high‐resolution TSE, HASTE provided clearer visualization of large leiomyomas and ovarian tumors but slightly poorer visualization of uterine cancer. In occlusion, HASTE sequence generates higher contrast and is free from motion and chemical shift artifact with much higher time efficacy. Because of limited image resolution, the HASTE sequence should be used when the high‐resolution TSE imaging is suboptimal.
Fast and ultrafast magnetic resonance imaging in renal lesions
Authors: Walter Christof , Jockenhöfer Anke , Heindel Walter , Phd Harald Kugel , Jung Gregor , Krahe Thomas , Krug Barbara , Lackner Klaus
Published: March 2007

Our purpose was to analyze and compare the image quality and contrast‐to‐noise ratio (CNR) of different fast T1‐ and T2‐weighted sequences with conventional spin‐echo sequences in renal MRI. Twenty‐three patients with focal renal lesions were examined with a T2‐weighted ultrafast turbo spin‐echo (UTSE) sequence with and without frequency selective fat suppression (SPIR), a combined gradient‐and‐spin‐echo sequence (GraSE), and a conventional spin‐echo sequence (SE). In addition, T1‐weighted images were obtained pre‐and postcontrast, using a fast spin‐echo sequence (TSE) with and without SPIR and the conventional SE sequence. Among the T2‐weighted images, the highest CNR and the best image quality were obtained with the UTSE sequence, followed by the fat‐suppressed UTSE sequence. GraSE and conventional SE sequences showed a significantly lower CNR and image quality (p < 0.05). The T1‐weighted sequences did not show significant differences, in either precontrast or postcontrast measurements. T2‐weighted UTSE with and without fat suppression combined excellent image quality and high CNR for imaging and detection of renal lesions. The T1‐weighted fast sequences provided no alternative to the gradient‐echo or to the conventional SE sequences. The results of this systematic study suggest the use of T2‐weighted fast techniques for improved diagnostic accuracy of renal MRI.
Vital sign changes during infant magnetic resonance examinations
Authors: Taber Katherine H. , Hayman L. Anne , Northrup S. Robert , Maturi Luxmi
Published: March 2007

Heart rate (HR) and blood oxygen saturation (SaO2) were monitored before and during clinically indicated MR examinations of newborns to (a) identify any temporal relationship between MR scanning and vital sign fluctuations and (b) assess the reliability of SaO2 monitoring of dynamic changes. Fluctuations in HR (but not in SaO2) that are temporally linked to the MR image acquisition occur in most neonates during routine clinical MR examinations.
Magnetic resonance imaging of shear wave propagation in excised tissue
Authors: Bishop Jonathan , Poole Greg , Leitch Michael , Plewes Donald B.
Published: March 2007

The propagation of shear waves in ex vivo tissue samples, agar/gel phantoms, and human volunteers was investigated. A moving coil apparatus was constructed to generate low acoustic frequency shear perturbations of 50 to 400 Hz. Oscillating gradients phase‐locked with the shear stimulus were used to generate a series of phase contrast images of the shear waves at different time‐points throughout the wave cycle. Quantitative measurements of wave velocity and attenuation were obtained to evaluate the effects of temperature, frequency, and tissue anisotropy. Results of these experiments demonstrate significant variation in shear wave behavior with tissue type, whereas frequency and anisotropic behavior was mixed. Temperature‐dependent behavior related mainly to the presence of fat. Propagation velocities ranged from 1 to 5 m/sec, and attenuation coefficients of from 1 to 3 nepers/unit wavelength, depending on tissue type. These results confirm the potential of elastic imaging attributable to the intrinsic variability of elastic properties observed in normal tissue, although some difficulty may be experienced in clinical implementation because of viscous attenuation in fat.
Determination of focal ischemic lesion volume in the rat brain using multispectral analysis
Authors: Carano Richard A. D. , Takano Kentaro , Helmer Karl G. , Tatlisumak Turgut , Irie Katsumi , Petruccelli Joseph D. , Fisher Marc , Sotak Christopher H.
Published: March 2007

Multispectral (MS) analysis was used to determine the ischemic lesion volume in the rat brain after permanent middle cerebral arterial occlusion. MS analysis used a four‐dimensional MS model consisting of an estimate of the average apparent diffusion coefficient of water (ADCay), T2, proton density, and perfusion. Four classification methods were investigated: (a) multivariate gaussian (MVG); (b) k‐nearest neighbor (k‐NN); (c) k‐means (KM); and (d) fuzzy c‐means (FCM). MVG and k‐NN classifiers are supervised methods requiring labeled training data to characterize the stroke lesion. Unsupervised classifiers (KM, FCM) do not require previous statistics or labeled training data, resulting in potentially greater clinical usefulness. All MS methods provided significant correlation with postmortem findings beyond the use of ADCav alone (partial correlation given the ADCav estimate: MVG, .66; k‐NN, .75; KM, .68; FCM, .70). This study demonstrates that MS analysis provides an improved estimate of ischemic lesion volume over that obtained from ADC alone.
Fat suppressed MRI of articular cartilage with a spatial‐spectral excitation pulse
Authors: Hardy Peter A. , Recht Michael P. , Piraino David W.
Published: March 2007

We developed a three‐dimensional, gradient‐recalled‐echo imaging technique that incorporates a short‐duration spatial‐spectral excitation pulse from the family of binomial pulses. Binomial pulses of different orders were tested on phantoms and on normal volunteers to find the composite pulse that produced in the shortest duration the most reliable fat suppression. Composite pulses employing unipolar slice‐selective gradients with explicit rewinder gradients between each radiofrequency (RF) pulse were compared with composite RF pulses employing alternating‐polarity, slice‐select gradients. The advantage of the sequences using the unipolar gradients is improved fat suppression. Images of the knees of volunteers produced with the composite RF pulse have contrast between fat and articular cartilage equivalent to that on images created by the gradient‐recalled‐echo imaging technique employing a conventional chemsat pulse. The optimum RF pulse consisted of three amplitude‐ and phase‐modulated pulses combined with unipolar slice‐select gradients.
Locally focused MRI of interventions
Authors: Kuperman Vadim Y. , Nagle Scott K. , Levin David N.
Published: March 2007

Certain interventional MR procedures would benefit from T2‐weighted imaging because of the sensitivity of T2‐weighted images to tissue damage and target lesion contrast. To acquire such images with reasonable temporal resolution, a single‐shot acquisition should be used because of the inherently long TR needed for T2 weighting. Unfortunately, most scanners require long readout times (eg, greater than 150 msec) and high bandwidths (eg, greater than 120 kHz) to perform conventional single‐shot imaging with high spatial resolution. The resulting images are thus degraded by unacceptable artifacts and noise levels. This study illustrates how to create locally focused MR images that have high spatial resolution in a region of interest and lower spatial resolution elsewhere in the image. Because these images can be created from sparse k‐space data, a scanner with modest gradients (eg, 10 mT/m maximal amplitude, 500 μsec minimal rise time) can acquire them after a single excitation with relatively short readout time and low bandwidth. This technique may make it practical to monitor interventions with T2‐weighted imaging. The method was illustrated by reconstructing dynamic changes, which were simulated experimentally by moving objects in the vicinity of a normal human head.
Single‐shot diffusion‐weighted RARE sequence: Application for temperature monitoring during hyperthermia session
Authors: II′yasov Kamil A. , Prof Jürgen Hennig
Published: March 2007

A diffusion‐sensitive single‐shot RARE (rapid acquisition with relaxation enhancement) sequence was implemented on a 2T whole‐body MRI system. The sequence was optimized for diffusion‐based MR thermometry, both on a conventional whole‐body gradient system and on a high‐performance gradient insert. The use of spin‐echo versus stimulated‐echo diffusion weighting is discussed as a function of gradient performance. Diffusion‐based temperature mapping was used to observe the effect of the geometry of the antenna used for radiofrequency (RF) hyperthermia on the temperature distribution. Temperature changes of ±.5°C in gel and ±2°C in a muscle sample in vitro could be detected within 16 seconds (gel) or 1 minute (muscle) at a spatial resolution of 2 × 2 × 8 mm. Temperature changes in vivo were also observed on human muscle cooled with ice with comparable sensitivity for the measured apparent diffusion coefficient (ADC) values.
MRI monitoring of laser ablation using optical flow
Authors: Zientara Gary P. , Saiviroonporn Pairash , Morrison Paul R. , Fried Marvin P. , Hushek Stephen G. , Kikinis Ron , Jolesz Ferenc A.
Published: March 2007

The optical flow method is used for visualizing and quantifying the dynamics of tissue changes observed by MRI during thermal ablations. An approach was implemented for parallel two‐dimensional optical flow calculations including the replacement of spurious velocities. Velocity magnitude results were found to be accurate in low‐noise cases in tests using series of synthetic images. Optical flow results are presented from thermal ablation experiments utilizing a homogeneous polyacrylamide gel phantom and heterogeneous rabbit liver tissue in vivo, exhibiting heating and cooling with the accompanying quantitative characterization of the dilation and contraction of the thermally affected region. Results demonstrate that optical flow is capable of noninvasive real‐time monitoring and control of interstitial laser therapy (ILT).
Interactive MR‐guided percutaneous nephrostomy
Authors: Hagspiel Klaus D. , Kandarpa Krishna , Silverman Stuart G.
Published: March 2007

Open‐configuration MRI systems have been recently introduced and hold promise to allow the performance of a variety of minimally invasive procedures. Experience with MR‐guided catheter‐based luminal interventions is experimental to date. This is the first case of a successful percutaneous nephrostomy tube placement in a patient in an interventional MR system. The procedure was performed completely under MR guidance, and technical aspects are reviewed and compared with other, established techniques for percutaneous nephrostomy placement.
Subungual glomus tumor: Combined use of MRI and three‐dimensional contrast MR angiography
Authors: Boudghene Frank P. , Gouny Pierre , Tassart Marc , Callard Patrice , Breton Caroline Le , Vayssairat Michel
Published: March 2007

We describe a case of digital glomus tumor diagnosed by MRI and three‐dimensional contrast MR angiography (MRA). Images provided the formal definitive diagnosis and the precise localization of the tumor, guiding the necessary surgical resection. It is possible that noninvasive MRA could replace conventional arteriography for the evaluation of patients with clinical suspicion of glomus tumor.
Functional MRI of the lumbar spine in erect position in a superconducting open‐configuration MR system: Preliminary results
Authors: Zamani Amir A. , Moriarty Thomas , Hsu Liangge , Winalski Carl S. , Schaffer Jonathan L. , Isbister Holly , Schenck John F. , Rohling Kenneth W. , Jolesz Ferenc
Published: March 2007

The purpose of this study was to determine the feasibility of obtaining, and findings in, functional MRI of the lumbar spine in an erect position and with flexion and extension. Thirty subjects (including 5 volunteers) were imaged in a sitting position and while performing flexion and extension. The alternations in posterior disk margin, size of neural foramina, and central canal were evaluated. In addition, routine supine imaging was accomplished in 15 of these subjects. The foraminal size and posterior disk margins did not change appreciably from supine to upright position. With extension, there was an increased disk bulge in 27% of disks (40% of those with desiccation). Central canal size (50%) and foraminal size (27%) decreased with extension, especially at levels with disk desiccation. Images obtained with our open‐configuration MR unit were diagnostically adequate, although of inferior quality compared with those obtained with a conventional unit. Our preliminary results show the feasibility of obtaining diagnostic images of the erect lumbar spine with flexion and extension. The results are in agreement with those obtained with cadaveric studies. The utility of this method in diagnostic imaging of patients with low back pain remains to be determined.
Black‐blood MR angiography with grase: Measurement of flow‐induced signal attenuation
Authors: Yu Beverly C. , Jara Hernan , Melhem Elias R. , Caruthers Shelton D. , Yucel E. Kent
Published: March 2007

We investigated the feasibility of performing black‐blood MR angiography (MRA) with the gradient and spin‐echo (GRASE) pulse sequence. Phantom experiments and human testing were conducted, and the results were compared with those of turbo spin‐echo (TSE). We demonstrated that both techniques are able to produce signal suppression of flowing fluid to background level. With fewer radiofrequency (RF)‐refocusing pulses, GRASE pulse sequences could serve as an alternative black‐blood technique of reduced RF power exposure and shorter scan time. These relative advantages of GRASE may become useful when high‐resolution images are taken.
Simultaneous qualification and quantification of eight triterpenoids in Radix Achyranthis Bidentatae by high‐performance liquid chromatography with evaporative light scattering detection and mass spectrometric detection
Authors: Li Juan , Li Ping , Li Hui‐Jun , Song Yue , Bi Zhi‐Ming , Li Yan‐Jing
Published: March 2007

An HPLC with evaporative light scattering detection (ELSD) and ESI‐MS was established for the simultaneous determination of eight triterpenoids in Radix Achyranthis Bidentatae. The optimal chromatographic conditions were achieved on a Zorbax C18 column by linear gradient elution with 0.08% v/v aqueous formic acid and ACN as the mobile phase at the flow rate of 0.8 mL/min. Temperature for the detector drift tube was set at 101°C and the nitrogen flow rate was 2.8 L/min. The identities of the analytes were accomplished by comparing retention times and mass data with those of reference compounds. The validation of the method included tests of linearity, sensitivity, repeatability, recovery, and stability. All the calibration curves of the eight triterpenoids showed good linear regression (R2 >0.997) within the test ranges. The method provides desirable repeatability with overall intra‐ and interday variations of less than 4.9%. The obtained recoveries varied between 93.6 and 98.1% while the RSDs were below 3.9% (n = 3). The analysis results indicate that the content of investigated triterpenoids in Radix Achyranthis Bidentatae from different locations was greatly diverse, and the triterpenoids could be used as chemical markers for the discrimination of genuine and ungenuine crude drugs.
Efficient Improvement of Fluorescence Quantum Yield of Fluoreneethynylene‐Based Polymers by Introducing a Perfluoroalkylbenzene Unit to the Polymers
Authors: Zeng Danli , Chen Junwu , Chen Zhao , Zhu Weihong , He Jun , Yu Feng , Huang Hao , Wu Huanrong , Liu Chang , Ren Shijie , Du Junping , Sun Jing , Xu Erjian , Cao Amin , Fang Qiang
Published: March 2007

In comparison with poly(9,9‐dialkylfluorene)s widely used in organic optoelectronic devices, poly(9,9‐dialkylfluoreneethynylene)s (PFEs) have attracted less attention partly because of their poor fluorescence quantum yield (FQY) in the solid state. In order to improve the FQY, a 1,4‐bis(perfluorohexyl)benzene (BFB) unit was introduced to PFEs, and the results showed that the absolute FQY in the solid state was dependent on the mol‐% of the BFB unit in the copolymers. When mol‐% was 40 and 50%, respectively, the absolute FQY had greatly increased from 4.9% of PFE to 7.8 and 17.4% of the copolymers, respectively. For comparison, a 1,4‐dihexylbenzene (DHB) unit was also introduced to PFE, whereas the obtained copolymer showed the absolute FQY of 3.8%, suggesting that the DHB unit was not suitable for improvement of the FQY of PFEs. Electrochemically, the PFE containing BFB units showed lower reduction potential than that of PFE. All the fluorine‐containing polymers have good thermal stability.

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Hydrogen Bonding‐Induced Transformation of Network Aggregates into Vesicles ‐ A Potential Method for the Preparation of Composite Vesicles
Authors: Zhang Jian Xiang , Li Xiao Dong , Yan Mei Qiu , Qiu Li Yan , Jin Yi , Zhu Kang Jie
Published: March 2007

While network‐like assemblies are formed by amphiphilic polyphosphazenes with poly(N‐isopropylacrylamide) and ethyl tryptophan as side groups in aqueous solution, a significant morphology transformation is observed when small molecules that exhibit hydrogen‐bonding interactions with amphiphilic copolymers are introduced during the preparation of polymeric assemblies through a dialysis procedure. Depending on copolymer composition and the content of small molecules introduced, aggregates ranging from general vesicles, high‐genus vesicles, to well‐defined nanospheres can be prepared successfully as clearly evidenced by TEM observation, which suggests this procedure should be a novel approach to prepare composite vesicles.

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Synthesis of Chain‐End Functionalized Polyolefins with a Bis(phenoxy imine) Titanium Catalyst
Authors: Makio Haruyuki , Fujita Terunori
Published: March 2007

Polyethylenes and highly syndiotactic poly(propylene)s possessing chain end hydroxyl groups were synthesized by living polymerizations using L2TiCl2 [1, L: C6F5NCH(2OC6H33tBu)]/MAO and functionalized α‐olefins, H2CCH(CH2)nY [2; YOAlMe2, n = 4 (2a); YOSiMe3, n = 9 (2b)]. Because the primary insertion of 2 to a cationic species L2Ti+Me (3) derived from 1/MAO is much faster than the successive secondary insertion of 2, addition of an equimolar amount of 2 to 3 resulted in the quantitative formation of L2Ti+CH2CH(Me)(CH2)nY [4; YOAlMe2, n = 4 (4a); YOSiMe3, n = 9 (4b)]. These cationic species 4 served as functionalized initiators for the living polymerization of both ethylene and propylene and afforded polyolefins having extremely narrow molecular weight distributions and a hydroxyl group at the initiating chain end. The terminating chain end of the syndiotactic poly(propylene)s was also functionalized by adding an excess amount of 2b as a chain end capping agent to the living L2Ti–polymeryl species. Due to much slower insertion of the second molecule of 2b relative to the first one, the obtained polymers were end capped quantitatively by a single molecule of 2b. Telechelic syndiotactic poly(propylene)s were successfully synthesized through a living polymerization initiated by 4b and an end capping using 2b.

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Orofacial automatisms induced by acute withdrawal from high‐dose midazolam mimicking nonconvulsive status epilepticus in a child
Authors: Epstein David , Difazio Marc
Published: March 2007

Nonconvulsive Status Epilepticus (NCSE) is not uncommon in children, and can be challenging to diagnose and treat. Etiologies vary widely and include infection, trauma and acute withdrawal from medications such as anticonvulsants. We report a child who experienced orofacial dyskinesias concerning for NCSE after withdrawal from high dose benzodiazepines andopiates. Automonic signs typically associated with sedative withdrawal were absent and treatment with benzodiazepines did not improve his symptoms. Diagnostic testing was negative, including electroencephalogram, and resolution was complete within five days. Our case demonstrates the orofacial dyskinesias that may occur during sedative medication withdrawal, and highlights potential confusion with non‐convulsive status epilepticus. © 2007 Movement Disorder Society
Cognitive‐behavioral therapy for depression in Parkinson's disease: A pilot study
Authors: Dobkin Roseanne DeFronzo , Allen Lesley A. , Menza Matthew
Published: March 2007

The present study was conducted to examine the feasibility and effect of an individual cognitive‐behavioral treatment (CBT) for depression that was modified to meet the unique needs of the PD patient and incorporated a separate social support intervention for caregivers. Fifteen PD patients with Major Depressive Disorder participated in the study with a caregiver. Patients received 10–14 sessions of modified individual CBT. Caregivers attended 3–4 psychoeducational sessions, occurring separately from the patients treatment sessions, which focused on strategies for offering appropriate support, and ways to respond to the patients' negative thoughts in a targeted manner. Patients experienced a significant reduction in depressive symptoms and negative cognitions, and an increased perception of social support over the course of treatment. Gains were maintained at 1‐month follow‐up. In conclusion, individual CBT, when modified appropriately, may be a feasible and effective option for PD depression. Larger, randomized controlled trials are needed to further evaluate the efficacy of this intervention and to identify specific mechanisms of change. © 2007 Movement Disorder Society
Global existence and blow‐up of the solutions for the multidimensional generalized Boussinesq equation
Authors: Wang Ying , Mu Chunlai
Published: March 2007

In this paper, the existence and the uniqueness of the global solution for the Cauchy problem of the multidimensional generalized Boussinesq equation are obtained. Furthermore, the blow‐up of the solution for the Cauchy problem of the generalized Boussinesq equation is proved. Copyright © 2007 John Wiley & Sons, Ltd.
Fredholm properties of multivariate refinement equations
Authors: Didenko Victor D.
Published: March 2007

The solvability of multivariate refinement equations in the Hilbert space L2(ℝs) is studied. It is shown that the set of all L2‐solutions of such equations either consists of the trivial solution only or it contains a subspace isomorphic to a space L∞(SM) where SM is a subset of ℝs with a positive Lebesgue measure. Therefore, the corresponding multivariate refinement operator is Fredholm if and only if it is invertible. Copyright © 2007 John Wiley & Sons, Ltd.
A detailed analysis of localized J‐difference GABA editing: theoretical and experimental study at 4 T
Authors: Kaiser L. G. , Young K. , Meyerhoff D. J. , Mueller S. G. , Matson G. B.
Published: March 2007

The problem of low signal‐to‐noise ratio for γ‐aminobutyric acid (GABA) in vivo is exacerbated by inefficient detection schemes and non‐optimal experimental parameters. To analyze the mechanisms for GABA signal loss of a MEGA‐PRESS J‐difference sequence at 4 T, numerical simulations were performed ranging from ideal to realistic experimental implementation, including volume selection and experimental radio frequency (RF) pulse shapes with a macromolecular minimization scheme. The simulations were found to be in good agreement with phantom and in vivo data from human brain. The overall GABA signal intensity for the simulations with realistic conditions for the MEGA‐PRESS difference spectrum was calculated to be almost half of the signal simulated under ideal conditions (∼43% signal loss). In contrast, creatine was reduced significantly less then GABA (∼19% signal loss). The ‘four‐compartment’ distribution due to J‐coupling in the PRESS‐based localization was one of the most significant sources of GABA signal loss, in addition to imperfect RF profiles for volume selection and editing. An alternative strategy that reduces signal loss due to the four‐compartment distribution is suggested. In summary, a detailed analysis of J‐difference editing is provided with estimates of the relative amounts of GABA signal losses due to various mechanisms. The numerical simulations presented in this study should facilitate both implementation of the more efficient acquisition and quantification process of J‐coupled systems. Copyright © 2007 John Wiley & Sons, Ltd.
Dimensioning and optimization of push‐to‐talk over cellular server
Authors: Alam M. T. , Wu Z. D.
Published: March 2007

The PoC (push‐to‐talk over cellular) application allows point‐to‐point or point‐to‐multipoint voice communication between mobile network users. The related work over PoC focuses on the performance analysis only and is ignorant about dimensioning a PoC controller to optimize revenue for service providers. In this paper, we dimension a PoC service with the assumption that the network grade of service is provided. The on‐demand sessions should have access priority over pre‐established sessions. A PoC controller should be able to terminate a PoC session based on an optimal timer. Moreover, the number of simultaneous session initiations by a PoC client is also a configurable parameter. We derived relations to provide access priority to special PoC sessions based on available transmit/receive units (TRU) and threshold level. Load sharing expressions are reported for a PoC controller using the Lagrange multiplier technique. A simple relation to control the PoC session timer is proposed. Finally, the derivation of maximum number of allowable simultaneous sessions is depicted using two‐state Markov models. Numerical results have been computed with the corresponding derivation to provide a useful insight into the system behaviour. A PoC service can benefit from these optimal values of our work during the busy hour. Copyright © 2007 John Wiley & Sons, Ltd.
Urine reagent stick protein determination: Utility in individuals with diabetes mellitus
Authors: Bloomgarden ZT
Published: March 2007

The study assessed the sensitivity and specificity of reagent stick urine analysis as a measure of albuminuria in individuals with diabetes mellitus. Using an automated method, reagent stick urine analysis for protein showed sensitivity and specificity both of 0.85 for detection of microalbuminuria (>25μg/ml). Visual reading of reagent strip protein showed similar sensitivity, but specificity was less than 0.6. In conclusion, the standard urine analysis test may offer specificity and sensitivity comparable to that of available microalbumin strips.
Comparison of the degradation of polycaprolactone and polycaprolactone–(β‐tricalcium phosphate) scaffolds in alkaline medium
Authors: Lam Christopher XF , Teoh Swee Hin , Hutmacher Dietmar W
Published: March 2007

The design and fabrication of scaffolds and biodegradable devices using slow‐degrading polymers and composites (degradation/resorption > 2 years) involve the necessity for long‐term in vitro and in vivo studies. If multiple designs and materials need to be tested, then this would use much time and financial resources. Accelerated degradation systems aim to achieve comparable degradation profiles within a shorter period of time. This investigation considers the hydrolytic degradation of polycaprolactone (PCL) and PCL–calcium phosphate (CaP) scaffolds in 5 mol L−1 NaOH at 37 °C. The scaffolds degrade via surface erosion, which proceeds in a consistent and predictable manner. The hydrolytic degradation of PCL‐based scaffolds alone is slow, governed by their high molecular weights, crystallinity, hydrophobicity, surface‐to‐volume ratio and porosity. The incorporation of CaP significantly increases the degradation rate. Copyright © 2007 Society of Chemical Industry
Modulus and damping of polymers in relation to their structure
Authors: Heijboer J.
Published: March 2007

For most applications of polymer products, the modulus or stiffness, i.e. resistance to deformation under load, is of prime importance. The mechanical losses or damping reveal molecular movements of small groups of atoms, which movements can be significant for the impact strength.

This review illustrates the effect of crosslinking, polarity, and steric features of both side‐groups and main molecular chain on both shear modulus and damping as functions of temperature.

The examples are mainly taken from commercial or recently developed polymers.

It is concluded that the most promising way of increasing the softening temperature of thermoplastics is to introduce rings into the main molecular chain.
Melamine‐formaldehyde resins: I. An examination of some model compound systems
Authors: Anderson I. H. , Cawley M. , Steedman W.
Published: March 2007

The possible course of methylotation and subsequent crosslinking steps in melamine‐formaldehyde resins has been investigated by using two model compound systems, viz., 2‐amino‐4, 6‐diphenoxy‐s‐triazine and 2‐amino‐4, 6‐diphenyl‐s‐triazine. The reactions of these models with formaldehyde and the secondary thermally induced condensation reactions have been examined, in particular, by the use of thin‐layer chromatography and by nuclear magnetic resonance and infra‐red spectroscopy. Methylolated products crosslink by forming ether and methylene bridges at ∼120°, the former being readily converted to the latter when the temperature is varied to ∼135°. Ether bridge degradation releases formaldehyde which further reacts in part at available N—H sites. The conversion of ether bridges to methylene bridges is enhanced by the attachment of phenyl groups to the triazine ring.
Wax crosslinking with dicumyl peroxide
Authors: Brink A. , Dressler F.
Published: March 2007

A Fischer—Tropsch paraffin wax of high molecular weight, congealing point 205°F (96·1°C), was crosslinked with dicumyl peroxide as initiator. At peroxide/wax molar ratios of less than 1·15 : 1, crosslinked waxes with molecular weights up to approximately double that of the starting material are obtained. These products are characterised by an increase in elasticity. At peroxide/wax ratios greater than 1·15 : 1 insoluble and infusible gels are formed. The efficiency and fate of the initiator and possible side reactions are discussed.
Liquid‐induced crystallisation of polymers
Authors: Kashmiri M. I. , Sheldon R. P.
Published: March 2007

In addition to the more conventional methods for promoting the crystallisation of polymers, treatment with certain organic liquids has been found to be effective. In previous work it has been shown that the mechanism of this process is a diffusion‐controlled one and that for thin films of polyethylene terephthalate, the crystallisation is completed by the development of opacity after a well‐defined induction time.

After a survey of possible methods it has been shown that an infra‐red technique is the most suitable for measuring the change in crystallinity, although doubt exists as to the reliability of the calculated magnitude of degrees of crystallinity. A comparison has been made between diffusion data and induction times and fair correlation is found to exist between log (diffusion coefficient) and induction time.
Structural information from the light scattered by solutions subjected to electric fields
Authors: Jennings B. R.
Published: March 2007

Measurements of the intensity of the light scattered from polymer solutions lead to information about geometric parameters such as the molecular weight and radius of gyration of the solute. The intensity changes when an electric field is applied to the solutions, owing to the resulting orientation, deformation and alignment of the polymer molecules. Measurements of these intensity changes lead to the evaluation of such physical parameters as the permanent and induced dipole moments and the relaxation time of the particles.

The theory of the effect is outlined briefly for rigid rod‐like and for flexible randomly coiled molecules. Two attractive aspects of the theory are that, in favourable circumstances, some measures of both the solute flexibility and polydispersity are obtainable in addition to the determination of the electrical properties of the polymer. Details of the inexpensive and straightforward modification and operation of an existing photoelectric photometer are mentioned.

Representative results are given for three systems. Aqueous dispersions of the needle‐like clay mineral attapulgite illustrate the abundance of molecular information obtainable by the method. Results for polybenzyl glutamate in the helix‐promoting solvent dichlorethane, demonstrate how an appraisal of the α‐helical configuration can be made in terms of the molecular length and dipole moment. Finally, results for polyproline show that, even with poorly characterised samples, useful qualitative information is still readily available. In this case, the molecular flexibility and dipolar nature were clearly shown.
Correlation of dielectric and visco‐elastic relaxation in polymer solutions
Authors: North A. M. , Phillips P. J.
Published: March 2007

The interpretation of studies of dielectric relaxation in polymers is often restricted by ignorance of the mode of motion responsible for dipole orientation in an applied field. Relevant information can be drawn from studies of visco‐elastic relaxation, since the visco‐elastic relaxation time is comparable with the dielectric relaxation time when the latter requires some ‘whole molecule’ mode of motion involving simultaneous movement of many chain segments. The dielectric and visco‐elastic relaxation times are expected to differ when the former involves a localised segmental motion.

The dielectric relaxation process is shown to involve a localised segmental motion in acrylic polymers, but involves a ‘whole molecule’ rotation in low molecular weight poly(N‐vinylcarbazole). Poly(p‐substituted phenyl acetylenes) exhibit two dielectric relaxation processes. A low frequency relaxation comparable with the visco‐elastic relaxation is ascribed to the backbone double bonds being polarised unidirectionally along the chain, and a high frequency process is ascribed to a localised segmental motion of the substituted phenyl moiety.
Azodiisobutyronitrile as initiator in emulsion polymerisation
Authors: Gulbekian E. V.
Published: March 2007

The solubility of azodiisobutyronitrile (AZDN), which is used as an initiator in emulsion polymerisation was measured in an aqueous phase containing a dissolved monomer and a surfactant. The results show that AZDN solubility is enhanced in the presence of dissolved monomer but that the surfactant alone has no appreciable effect.
Influence of chemical structure on the morphology and physical properties of crosslinked macromolecules synthesised by polyaddition reaction
Authors: Lohse F. , Schmid R. , Batzer H. , Fisch W.
Published: March 2007

By reacting acid polyesters with di‐epoxides and crosslinking them with anhydrides it was possible to increase the energy of deformation in the transition range by a factor of 10, compared with the conventional highly crosslinked epoxy resins.

A further increase in toughness could be realised by introducing hydrogen bonds, e.g. urethane groups along the chains of the polymers. The syntheses of epoxy resins containing urethane groups are described. The physical properties of the crosslinked systems caused by different densities of the crosslinks are demonstrated and discussed.
Synthesis of polymer particles possessing radical initiating sites on the surface by emulsion copolymerization and construction of core–shell structures by a photoinduced atom transfer radical polymerization approach
Authors: Ishizu Koji , Kobayakawa Naoyuki , Takano Satoshi , Tokuno Yoko , Ozawa Masaaki
Published: March 2007

The crosslinked polystyrene particles possessing photofunctional N,N‐diethyldithiocarbamate groups on their surface were prepared by free‐radical emulsion copolymerization of a mixture of styrene, divinylbenzene and 4‐vinylbenzyl N,N‐diethyldithiocarbamate with redox system as an initiator under UV irradiation. In this copolymerization, the inimer 4‐vinylbenzyl N,N‐diethyldithiocarbamate acted the formation of hyperbranched structures by living radical photopolymerization. The particle sizes (number‐average particle diameter = 214–523 nm) were controlled by varying the feed amount of surfactant and size distributions were relatively narrow. Subsequently, core–shell particles were synthesized by photoinduced atom transfer radical polymerization approach of methyl methacrylate initiated by photofunctional polystyrene particles as a macroinitiator. Such core–shell particles were stabilized sterically by grafted chains in organic solvents. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1771–1777, 2007
Aqueous solution and solid state interactions of lanthanide ions with a methacrylic ester polymer bearing pendant 15‐crown‐5 moieties
Authors: Rubio F. , García F. , Burrows H. D. , Pais A. A. C. C. , Valente A. J. M. , Tapia M. J. , García J. M.
Published: March 2007

The interaction between trivalent lanthanide ions and poly(1,4,7,10,13‐pentaoxacyclopentadecan‐2‐yl‐methyl methacrylate), PCR5, in aqueous solution and in the solid state have been studied. In aqueous solution, evidence of a weak interaction between the lanthanides and PCR5 comes from the small red shift of the Ce(III) emission spectra and the slight broadening of the Gd(III) EPR spectra. From the Tb(III) lifetimes in the presence of H2O and D2O the loss of one or two water coordinated molecules is confirmed when Tb(III) is bound to PCR5. An association constant of the order of 200 M−1 was obtained for a 1:1 (lanthanide:15‐crown‐5) complex from the shift of the polymer NMR signals induced by Tb(III). A similar association constant is obtained from the differences of the molar conductivity of Ce(III) solution at various concentrations in presence and absence of PCR5. When Tb(III) is adsorbed on PCR5 membranes, lifetime experiments in H2O and D2O confirm the loss of 5 or 6 water coordinated molecules indicating that in solid state the lanthanide(III)‐PCR5 interaction is stronger than in solution. The adsorption of Ce(III) in PCR5 membranes shows a Langmuir type isotherm, from which an equilibrium constant of 39 M−1 has been calculated. SEM shows that the membrane morphology is not much affected by lanthanide adsorption. Support for lanthanide ion–crown interactions comes from ab initio calculations on 15‐crown‐5/La(III) complex. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1788–1799, 2007
Overexpression of protease‐activated receptors‐1,‐2, and‐4 (PAR‐1, ‐2, and ‐4) in prostate cancer
Authors: Black Peter C. , Mize Gregory J. , Karlin Peter , Greenberg Daniel L. , Hawley Sarah J. , True Lawrence D. , Vessella Robert L. , Takayama Thomas K.
Published: March 2007

BACKGROUND

Although protease‐activated receptors (PARs) have been described to play a role in different malignancies, their expression and biological activity in prostate cancer are mostly unknown.

METHODS

PAR expression in radical prostatectomy specimens was investigated by immunohistochemistry (IHC, 40 patients) and RT‐PCR. Their role in LNCaP prostate cancer cell migration and Rac1/Cdc42 signaling was assessed with Boyden chamber analysis and Western blot, respectively.

RESULTS

PAR mRNA expression was higher in cancer, and protein expression was increased in PAR‐1 (45%), PAR‐2 (42%), and PAR‐4 (68%), compared to normal glands. Increased PAR‐1 (periglandular stroma) was associated with higher rates of biochemical recurrence (median follow‐up, 5 years;P = 0.006). LNCaP migration was enhanced twofold and Rac1/Cdc42 signaling was activated by stimulation of PAR‐1 and PAR‐2.

CONCLUSIONS

PARs are overexpressed in prostate cancer and may serve as potential predictors of recurrence. The data suggest potential role of PARs in autocrine and paracrine mechanisms of prostate cancer. Prostate 67: 743–756, 2007. © 2007 Wiley‐Liss, Inc.
Effects of steroidal and non‐steroidal antiandrogens on wild‐type and mutant androgen receptors
Authors: Urushibara Masayasu , Ishioka Junichiro , Hyochi Nobuhiko , Kihara Kazunori , Hara Shuntaro , Singh Pratap , Isaacs John T. , Kageyama Yukio
Published: March 2007

BACKGROUND

Molecular basis for secondary antiandrogen therapy in prostate cancer with mutant androgen receptors (ARs) is not fully elucidated.

MATERIALS AND METHODS

Effects of steroidal and non‐steroidal antiandrogens on transcriptional activities of wild‐type and mutant (W741C, T877A, and W741C+T877A) ARs were measured. Crystal structure analysis and docking studies were performed using Molecular Operating Environment (MOE) package.

RESULTS

DHT‐induced transcriptional activity of the T877A mutant and the W741C mutant was suppressed by bicalutamide and hydroxyflutamide, respectively. Nilutamide suppressed the W741C mutant and the double mutant. Cyproterone acetate modestly inhibited the W741C mutant and the double mutant. The structural studies suggested that nilutamide and cyproterone acetate retain their antiandrogenic properties against both the W741C mutant and the double mutant due to fact that mutation W741C does not permit formation of key hydrophobic interaction between ligand and AR ligand binding domain, which is necessary for their conversion into agonists.

CONCLUSIONS

Switching antiandrogens may be reasonable in prostate cancer with mutant ARs. Prostate 67: 799–807, 2007. © 2007 Wiley‐Liss, Inc.
Prospective diagnostic efficiency of biopsy washing DNA GSTP1 island hypermethylation for detection of adenocarcinoma of the prostate
Authors: Eilers Tyark , Machtens Stefan , Tezval Hossein , Blaue Christoph , Lichtinghagen Ralf , Hagemann Jörn , Jonas Udo , Serth Jürgen
Published: March 2007

BACKGROUND

The prospective diagnostic efficiency of quantitative glutathione S transferase (GSTP1) promoter hypermethylation analysis in biopsy washing samples has not been determined so far.

METHODS

Biopsies were obtained prospectively from 86 patients suspicious for prostate cancer (CaP). After isolation of DNA from biopsy washings and bisulfite conversion methylated and unmethylated GSTP1 sequences were specifically quantitated by real‐time fluorescence PCR. Relative degrees of methylation were compared to results of histopathological examination.

RESULTS

Increased relative methylation was found for the CaP group (mean 28.1%) compared to biopsies without histological evidence for malignancy (5.2%; P < 0.001). A sensitivity and specificity of 92% and 86% and positive and negative predictive values of 82% and 94% were obtained. Receiver operating characteristic (ROC) analysis demonstrated a value of 0.90 (95% CI 0.82–0.98) for the area under curve (AUC).

CONCLUSIONS

Biopsy washing DNA GSTP1 hypermethylation analysis demonstrates a high diagnostic efficacy which is comparable to the retrospective analysis of biopsy tissue specimens. Moreover it is compatible with routine biopsy examination thus permitting further prospective evaluation in CaP diagnosis. Prostate 67: 757–763, 2007. © 2007 Wiley‐Liss, Inc.
Interleukin‐6 undergoes transition from growth inhibitor associated with neuroendocrine differentiation to stimulator accompanied by androgen receptor activation during LNCaP prostate cancer cell progression
Authors: Lee Soo Ok , Chun Jae Yeon , Nadiminty Nagalakshmi , Lou Wei , Gao Allen C.
Published: March 2007

BACKGROUND

Interleukin‐6 (IL‐6) has been implicated in the modulation of growth and differentiation in many cancers, and is associated with poor prognosis in renal cell carcinoma, ovarian cancer, lymphoma, melanoma, and prostate cancer. The effects of IL‐6 on the growth of LNCaP human prostate cancer cells are puzzling with some groups showing growth stimulation, while others showing growth inhibition. In this study, we investigated the discrepancy of the effects of IL‐6 on prostate cancer cells.

METHODS

Series of lower and higher passages of LNCaP cell sublines were generated by a long‐term exposure of LNCaP cells in IL‐6‐containing culture media. The characteristics of these cell sublines were analyzed and the potential roles of neuroendocrine (NE) differentiation and androgen receptor (AR) activation were examined.

RESULTS

We demonstrated that while short‐term treatment of IL‐6 inhibits LNCaP cell growth by a paracrine mechanism associated with NE differentiation, long‐term treatment of IL‐6 promotes LNCaP cell growth by an autocrine mechanism accompanied by an activation of AR signaling. In the lower passages (less than 28 passages) of LNCaP cells treated with IL‐6, the cell growth was severely retarded which is associated with NE‐like morphology and increased expression of NE markers such as neuronspecific enolase (NSE) and chromgranin A (ChgA), and loss of AR expression. However, in the higher passages (higher than 42 passages) of LNCaP cells treated with IL‐6, cells started to express endogenous IL‐6. At the same time, NE characteristics were disappeared, AR signaling was activated and cells growth was accelerated. Knocking down the AR activation of the higher passages of LNCaP cells abolished autocrine IL‐6‐induced growth stimulation.

CONCLUSIONS

These studies suggest that acquisition of endogenous IL‐6 production after prolong exposure of prostate cancer cells to IL‐6 may contribute to an autocrine cell growth stimulation. Furthermore, the transition of IL‐6 from a paracrine growth inhibitor to an autocrine growth stimulator suggests that IL‐6 plays an important role during prostate cancer progression, possibly androgen‐independent progression. Prostate 67: 764–773, 2007. © 2007 Wiley‐Liss, Inc.
Toll like receptor‐9 agonists stimulate prostate cancer invasion in vitro
Authors: Ilvesaro Joanna M. , Merrell Melinda A. , Swain Telisha Millender , Davidson Jennifer , Zayzafoon Majd , Harris Kevin W. , Selander Katri S.
Published: March 2007

BACKGROUND

Toll‐like receptor 9 (TLR9) recognizes microbial DNA. In addition to immune cells, TLR9 expression has been detected in various cancer cells. We showed recently that TLR9 agonistic CpG‐oligonucleotides (CpG‐ODNs) induce matrix metalloproteinase‐13 (MMP‐13)‐mediated invasion in TLR9‐expressing (TLR9+) breast cancer cells. We investigated here TLR9 expression and function in human prostate cancer (CaP) cells.

METHODS

TLR9 expression was detected with Western blotting and immunohistochemistry. Invasion was studied with Matrigel‐assays. MMP‐13 was assayed with ELISA.

RESULTS

Human CaP cell lines and clinical samples exhibit various levels of TLR9 expression. Treatment of TLR9+, but not TLR9− CaP cells with CpG‐ODNs or bacterial DNA increased their invasion, which was inhibited with chloroquine. CpG‐ODN‐treatment also increased MMP‐13 activity and neutralizing anti‐MMP‐13 antibody prevented CpG‐ODN‐induced invasion in TLR9+ CaP cells. Estradiol up‐regulated TLR9 expression in LnCaP cells.

CONCLUSIONS

TLR9‐mediated invasion may represent a novel mechanism through which infections promote prostate cancer. Prostate 67: 774–781, 2007. © 2007 Wiley‐Liss, Inc.