bluuebunny/crossref_metadata_2025 huggingface dataset:
Executive processes in Parkinson's disease: FDG‐PET and network analysis
Authors: Lozza Catherine , Baron Jean‐Claude , Eidelberg David , Mentis Marc J. , Carbon Maren , Marié Rose‐Marie
Published: May 2004

It is assumed widely that the clinical expression of Parkinson's Disease (PD), both motor and cognitive, is subtended by topographically distributed brain networks. However, little is known about the functional neuroanatomy of executive dysfunction in PD. Our objective was to validate further in a PD group the use of network analysis to assess the relationship between executive processes and pathological disorganization of frontostriatal networks. We studied 15 patients with idiopathic PD, and 7 age‐matched normal controls, using resting [18F]fluorodeoxyglucose (FDG) and high‐resolution positron emission tomography (PET). We carried out network analysis on regional metabolic data to identify specific covariation patterns associated with motor and executive dysfunction. We detected two independent patterns relating respectively to the two clinical abnormalities. The first pattern (principal component 1) was topographically similar to that described previously in other PD populations. Subject scores for this pattern discriminated patients from controls and correlated significantly with bradykinesia ratings (P = 0.013, r = 0.655) in PD patients. The second pattern (principal component 2) was characterized by relative ventromedial frontal, hippocampal, and striatal hypometabolism, associated with mediodorsal thalamic hypermetabolism. In the PD group, scores from this pattern correlated with scores on the conditional associative learning (CAL; P = 0.01, r = 0.690) and the Brown Peterson paradigm (BPP; P = 0.017, r = −0.651) tests, respectively assessing strategy and planning, and working memory. According to these findings, the networks subserving bradykinesia and executive dysfunction in PD seems to be topographically distinct and to involve different aspects of subcortico‐cortical processing. Hum. Brain Mapping 22:236–245, 2004. © 2004 Wiley‐Liss, Inc.
Autoradiographic distribution of serotonin transporters and receptor subtypes in human brain
Authors: Varnäs Katarina , Halldin Christer , Hall Håkan
Published: May 2004

Several neurochemical in vitro and in vivo imaging studies have been aimed at characterizing the localization of serotonin receptors and transporters in the human brain. In this study, a detailed comparison of the distribution of a number of 5‐HT receptor subtypes and the 5‐HT transporter was carried out in vitro using human postmortem brain tissue. Anatomically adjacent whole hemisphere sections were incubated with specific radioligands for the 5‐HT1A, 5‐HT1B, 5‐HT2A, 5‐HT4 receptors and the 5‐HT transporter. The autoradiograms revealed different laminar and regional distribution patterns in the isocortex, where 5‐HT1A and 5‐HT4 receptor binding showed highest densities in superficial layers and 5‐HT2A receptor binding was most abundant in middle layers. In cortical regions, 5‐HT transporters were concentrated to several limbic lobe structures (posterior uncus, entorhinal, cingulate, insular and temporal polar regions). 5‐HT1A receptor densities were also high in limbic cortical regions (hippocampus, posterior entorhinal cortex, and subcallosal area) compared to the isocortex. Subregionally different distribution patterns were observed in the basal ganglia with a trend toward higher levels in ventral striatal (5‐HT1B receptors) and pallidal (5‐HT transporters and 5‐HT1B receptors) regions. The localization in regions belonging to limbic cortico‐striato‐pallido‐thalamic circuits is in line with the documented role of 5‐HT in modulation of mood and emotion, and the suggested involvement of this system in pathophysiology of various psychiatric disorders. The qualitative and quantitative information reported in this study might provide important complements to in vivo neuroimaging studies of the 5‐HT system. Hum. Brain Mapping 22:246–260, 2004. © 2004 Wiley‐Liss, Inc.
High‐dose superselective intra‐arterial cisplatin and concomitant radiation (radplat) for advanced head and neck cancer
Authors: Balm Alfons J. M. , Rasch Coen R. N. , Schornagel Jan H. , Hilgers Frans J. M. , Keus Ronald B. , Schultze‐Kool Leo , Ackerstaff Annemieke H. , Busschers Wim , Tan I. Bing
Published: May 2004

Background.

The purpose of this study was to study the effect of intensive targeted chemoradiation in a group of patients with head and neck cancer with stage IV inoperable disease.

Methods.

We examined 79 patients with inoperable stage IV head and neck cancer receiving intra‐arterial infusion of high‐dose cisplatin (150 mg/m2) on days 2, 9, 16, and 23 concomitant with delivery of external beam radiotherapy (total dose, 70 Gy; 2 Gy, 35 fractions; 1 fraction/day for 7 weeks). Sodium thiosulfate was administered intravenously to provide effective cisplatin neutralization.

Results.

Four patients were not assessable. Complete local tumor response was achieved in 72 patients (91%) and a partial response in three patients. The complete response rate of neck node metastases was 90%. The 1‐ and 2‐year locoregional control rates were 82% and 69%, respectively. The median overall survival time was 2.2 years, with a 3‐year overall survival probability of 43%. Acute toxicities were as follows: grade III/IV hematologic toxicity (22%/16%), grade III/IV nephrotoxicity (0%), grade III mucositis (43%), grade III skin reactions (24%), grade III toxicity of the upper gastrointestinal tract (57%), grade III nausea (20%), and grade III subjective hearing loss (10%). Grade V toxicity (treatment‐related deaths) was 3.8%. Six (18%) of 33 patients with complete remission needed tube feeding 2 years after treatment without intercurrent salvage surgery.

Conclusions.

Supradose superselective intra‐arterial cisplatin and concomitant radiation is an effective organ‐preserving therapy in an unfavorable group of patients. Our series confirms encouraging results reported previously. This regimen is justified in unresectable patients despite the substantial toxicity. © 2004 Wiley Periodicals, Inc. Head Neck 26: 485–493, 2004
A pilot study of a randomized controlled trial to evaluate the effects of progressive resistance exercise training on shoulder dysfunction caused by spinal accessory neurapraxia/neurectomy in head and neck cancer survivors
Authors: McNeely Margaret L. , Parliament Matthew , Courneya Kerry S. , Seikaly Hadi , Jha Naresh , Scrimger Rufus , Hanson John
Published: May 2004

Background.

Shoulder dysfunction remains a frequent complication after neck dissection procedures for head and neck cancer.

Methods.

We conducted a pilot study to evaluate the effects of progressive resistance exercise training (PRET) on shoulder dysfunction caused by spinal accessory neurapraxia/neurectomy in patients with head and neck cancer. Twenty patients (mean age, 61 ± 7.7 years) were randomly assigned to PRET or standard care intervention. Subjects assigned to the PRET group exercised three times per week for 12 weeks. The goal of the exercise program was to enhance scapular stability and strength of the upper extremity. The resistance‐training program was progressive in terms of number of sets and repetitions performed, as well as the amount of weight lifted, depending on performance status.

Results.

The completion rate for the trial was 85% (17 of 20). The exercise group completed 93% of scheduled exercise sessions. Significant improvements were found in favor of the PRET group in active shoulder external rotation (p = .001), shoulder pain (p = .038), and overall score for shoulder pain and disability (p = .045).

Conclusions.

The study results demonstrate a high rate of completion and adherence with our PRET program among patients with head and neck cancer. The preliminary findings, although limited, also suggest a potential therapeutic role for resistance exercise as an adjunct to standard physical therapy treatment. © 2004 Wiley Periodicals, Inc. Head Neck 26: 518–530, 2004
Transcription factor NF‐κB activation after in vivo perforant path LTP in mouse hippocampus
Authors: Freudenthal Ramiro , Romano Arturo , Routtenberg Aryeh
Published: May 2004

There is increasing evidence that transcription factors (TFs) play a critical role in maintaining later phases of hippocampal long‐term potentiation (LTP). We have been led to study the role in synaptic plasticity of the powerful, yet generally unheralded, NF‐κB TF because it may serve as both a signaling molecule after its activation at the synapse and then a transcription initiator upon reaching the nucleus. In the present study, we show that LTP activates NF‐κB in the intact mouse hippocampus. Mice were sacrificed 15 min after one of three treatments: tetanization (high‐frequency stimulation [HFS]), low‐frequency stimulation (LFS), or no stimulated control animals (CT). In a first study, nuclear NF‐κB activity from hippocampus was estimated by electrophoretic mobility shift assays (EMSAs). A higher level of hippocampal TF binding to the NF‐κB recognition element was found in the HFS group compared with LFS or CT. In a second study, NF‐κB activity was evaluated by immunohistochemistry with a specific antibody that recognizes the activated form of NF‐κB. This antibody binds to the exposed nuclear location sequence on the p65 subunit of NF‐κB consequent to its dissociation from the inhibitory IκB molecule. In the four subfields of hippocampus examined—granule cell layer, hilus of the dentate gyrus, CA3 and CA1 pyramidal fields of the hippocampal gyrus—the highest levels of activated NF‐κB, statistically significant in all cases were found after HFS. In certain comparisons, LFS animals also showed significant elevation with respect to CT. These results support the role of NF‐κB as part of the synaptic signaling and transcriptional regulation mechanism required in long‐term plasticity, emphasizing the combinatorial nature of TF function. © 2004 Wiley‐Liss, Inc.
Thermal residual stresses near the interface between plasma‐sprayed hydroxyapatite coating and titanium substrate: Finite element analysis and synchrotron radiation measurements
Authors: Cofino B. , Fogarassy P. , Millet P. , Lodini A.
Published: May 2004

Plasma‐sprayed hydroxyapatite (HA) coatings on titanium alloy are often used in prosthetic implants. The metallic substrate gives the implant good mechanical strength which is combined with good biocompatibility and osteointegration of the ceramic coating. However, the interface between the HA coating and titanium alloy substrate is an area of critical weakness when compared with the interlamellar cohesive strength of the HA coating structure. Knowledge of the stresses in materials near the interface seems to be an important step in understanding why failure occurs. Synchrotron radiation, using Beamline BM16 at the European Synchrotron Radiation Facility (Grenoble, France), has been used to determine local stresses near the interface, down to 10 μm in resolution, between a plasma‐sprayed HA coating and a titanium alloy substrate. This experimental determination of residual stresses is compared with the results found by a finite element analysis modeling the thermal effects of the plasma‐spraying process. Residual stresses have been found in deposited ceramic near the interface due to a thermal properties mismatch of the materials. If the plane stress state is assumed, meaning the perpendicular component of residual stress is ignored (σz = 0), then the synchrotron residual stress measurements should be interpreted as mainly compressive in the ceramic coating. This is in contradiction with the coefficient of thermal expansion mismatch; therefore, the simplified plane stresses assumption seems to be inappropriate for the deposited morphology characterized by pores and a network of microcracks. The detailed finite element analysis model, taking into account the real morphology of the coating and the real three‐dimensional stress field distribution, allowed the estimation of σz, leading to a more accurate interpretation of synchrotron measurements, which is validated by the experimental results. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 70A: 20–27, 2004
Preparation of poly(ethylene glycol)‐block‐poly(caprolactone) copolymers and their applications as thermo‐sensitive materials
Authors: Kim Moon Suk , Seo Kwang Su , Khang Gilson , Cho Sun Hang , Lee Hai Bang
Published: May 2004

The polymerization of ϵ‐caprolactone (ϵ‐CL) was initiated by the terminal alcohol of methoxy poly(ethylene glycol) (MPEG) as an initiator via activated ring‐opening polymerization in the presence of HCl · Et2O as a monomer activator. The molecular weights of the poly(ϵ‐caprolactone) (PCL) in MPEG–PCL diblock copolymers controlled with the feed ratio of ϵ‐CL to MPEG. The polymerization was preceded by living fashion with no termination or chain transfer. This polymerization procedure offered MPEG–PCL diblock copolymers with well‐defined structures. The gel‐to‐sol transitions of MPEG–PCL diblock copolymer solutions were also examined. The diblock copolymers synthesized with various MPEG and PCL lengths were dissolved in water at 80°C in various concentrations. The polymer solutions formed gel at room temperature. The formed gel became fluids again by increasing the temperature. The gel‐to‐sol transition showed strong dependence on the length of the MPEG and PCL diblock segments. When the polymer solution was injected into rat, it became a gel at body temperature. The formed gel maintained for 1 month. We confirmed that MPEG–PCL diblock copolymers with well‐defined structures served as new thermo‐sensitive biomaterials. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 70A: 154–158, 2004
Biocompatibility and osseointegration of β‐TCP: Histomorphological and biomechanical studies in a weight‐bearing sheep model
Authors: Koepp Holger E. , Schorlemmer Sandra , Kessler Stefan , Brenner Rolf E. , Claes Lutz , Günther Klaus‐Peter , Ignatius Anita A.
Published: May 2004

The aim of the study was to investigate the biocompatibility, degradation, and biomechanical properties of β‐TCP (Cerasorb®) in a weight‐bearing sheep model. β‐TCP implant prototypes were implanted in the tibial head of adult merino sheep. After 6 and 12 months material explants were harvested for biomechanical, histological, and histomorphometrical analysis. Corresponding bone specimens of the intact bone of the contralateral leg were used as controls in the biomechanical test. Compression tests showed higher values for maximum fracture load, yield strength, and compression modulus after 6 and 12 months compared to control. Microscopically, the implants showed good osteoconduction and were incorporated into the bone; however, relevant amounts of β‐TCP were still present after 12 months. Histomorphological results revealed that β‐TCP had partially degraded between implantation and 6 months, but its share remained constant between 6 and 12 months. The bone volume fraction in the area of the implant (46% ± 6.5%) was initially higher than in the corresponding bone area of the contralateral leg (31% ± 9.6%), but after 12 months declined to 29% ± 9.4% (control: 33% ± 8.3%), while the share of β‐TCP remained constant at 36% ± 12.2%. These findings were supported by microradiographic data. In conclusion, in a weight bearing implantation model β‐TCP showed good biocompatibility, osseointegration and beginning degradation, even though it was not further degraded between 6 and 12 months. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 70B: 209–217, 2004
Bioresorbable nanofiber‐based systems for wound healing and drug delivery: Optimization of fabrication parameters
Authors: Katti Dhirendra S. , Robinson Kyle W. , Ko Frank K. , Laurencin Cato T.
Published: May 2004

Wound healing is a complex process that often requires treatment with antibiotics. This article reports the initial development of a biodegradable polymeric nanofiber‐based antibiotic delivery system. The functions of such a system would be (a) to serve as a biodegradable gauze, and (b) to serve as an antibiotic delivery system. The polymer used in this study was poly(lactide‐co‐glycolide) (PLAGA), and nanofibers of PLAGA were fabricated with the use of the electrospinning process. The objective of this study was to determine the effect of fabrication parameters: orifice diameter (needle gauge), polymer solution concentration, and voltage per unit length, on the morphology and diameter of electrospun nanofibers. The needle gauges studied were 16 (1.19 mm), 18 (0.84 mm), and 20 (0.58 mm), and the range of polymer solution concentration studied was from 0.10 g/mL to 0.30 g/mL. The effect of voltage was determined by varying the voltage per unit electrospinning distance, and the range studied was from 0.375 kV/cm to 1.5 kV/cm. In addition, the mass per unit area of the electrospun nanofibers as a function of time was determined and the feasibility of antibiotic (cefazolin) loading into the nanofibers was also studied. The results indicate that the diameter of nanofibers decreased with an increase in needle gauge (decrease in orifice diameter), and increased with an increase in the concentration of the polymer solution. The voltage study demonstrated that the average diameter of the nanofibers decreased with an increase in voltage. However, the effect of voltage on fiber diameter was less pronounced as compared to polymer solution concentration. The results of the areal density study indicated that the mass per unit area of the electrospun nanofibers increased linearly with time. Feasibility of drug incorporation into the nanofibers was demonstrated with the use of cefazolin, a broad‐spectrum antibiotic. Overall, these studies demonstrated that PLAGA nanofibers can be tailored to desired diameters through modifications in processing parameters, and that antibiotics such as cefazolin can be incorporated into these nanofibers. Therefore, PLAGA nanofibers show potential as antibiotic delivery systems for the treatment of wounds. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 70B: 286–296, 2004
Improved collagen bilayer dressing for the controlled release of drugs
Authors: Sripriya Ramasamy , Kumar Muthusamy Senthil , Sehgal Praveen Kumar
Published: May 2004

A novel bilayer dressing has been developed from bovine succinylated collagen. The dressing contains an antibiotic, Ciprofloxacin, for both immediate and time‐regulated release for controlling the infection, as the infected open wounds need special care. The dressing consists of a sponge and a film, both prepared from succinylated bovine collagen. The sponge has a smooth surface on one side; its rough surface on the other side forms the bilayer system with the film. Both sponge and film act as an anionic reservoir to hold the cationic Ciprofloxacin. The drug, after dispersing in poly (N‐vinyl‐2‐pyrrolidione) (PVP) solution is allowed to spread in the bilayer system by diffusion. The drug stays in the bilayer system because of ionic binding, but starts releasing when comes in contact with the wound. Release of the drug is immediate, but it is regulated by ionic binding between the drug and succinylated collagen. The wound exudates, and there is a polarity‐controlled release of the drug from the bilayer system. The PVP and bilayer system permits only time‐regulated release, and the system lasts up to 5 days with therapeutically sufficient drug availability. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 70B: 389–396, 2004
The behavior of novel hydrophilic composite bone cements in simulated body fluids
Authors: Boesel Luciano F. , Fernandes Maria H. V. , Reis Rui L.
Published: May 2004

Composite bone cements were formulated with bioactive glass (MgOSiO23CaO · P2O5) as the filler and hydrophilic matrix. The matrix was composed of a starch/cellulose acetate blend (SCA) as the solid component and a mixture of methylmethacrylate/acrylic acid (MMA/AA) as the liquid component. The curing parameters, mechanical properties, and bioactive behavior of these composite cements were determined. The addition of up to 30 wt % of glass improved both compressive modulus and yield strength and kept the maximum curing temperature at the same value presented by a typical acrylic‐based commercial formulation. The lack of a strongly bonded interface (because no coupling agent was used) had important effects on the swelling and mechanical properties of the novel bone cements. However, bone cements containing AA did not show a bioactive behavior, because of the deleterious effect of this monomer on the calcium phosphate precipitation on the polymeric surfaces. Formulations without AA were prepared with MMA or 2‐hydroxyethyl methacrylate (HEMA) as the liquid component. Only these formulations could form an apatite‐like layer on their surface. These systems, therefore, are very promising: They are bioactive, hydrophilic, partially degradable, and present interesting mechanical properties. This combination of properties could facilitate the release of bioactive agents from the cement, allow bone ingrowth in the cement, and induce a press‐fitting effect, improving the interfaces with both the prosthesis and the bone. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 70B: 368–377, 2004
Porous alginate/hydroxyapatite composite scaffolds for bone tissue engineering: Preparation, characterization, and in vitro studies
Authors: Lin Hong‐Ru , Yeh Yu‐Jen
Published: May 2004

In this study a series of alginate/hydroxyapatite (HAP) composite scaffolds was prepared by phase separation. HAP was incorporated into the alginate gel solution to improve both the mechanical and cell‐attachment properties of the scaffolds. These scaffolds had a well‐interconnected porous structure with an average pore size of 150 μm and over 82% porosity. The alginate/HAP scaffold prepared at −40°C with a 50% HAP content showed the best mechanical properties. The morphology of scaffolds could be manipulated by tuning the quenching temperature during the preparation. The dissolution of alginate/HAP composite scaffolds could be slowed by the pretreating them by immersion in 1.0M CaCl2 solution. The rat osteosarcoma UMR106 cells, an osteoblastic cell line, seeded in the scaffolds, displayed better cell attachment to the 75/25 and 50/50 alginate/HAP composite scaffolds than to the pure alginate scaffold. The natural polymeric sponges that fabricated in this study may be a promising approach for tissue‐engineering applications. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 52–65, 2004
Development of the force field parameters for phosphoimidazole and phosphohistidine
Authors: Kosinsky Yuri A. , Volynsky Pavel E. , Lagant Philippe , Vergoten Gerard , Suzuki Ei‐Ichiro , Arseniev Alexander S. , Efremov Roman G.
Published: May 2004

Phosphorylation of histidine‐containing proteins is a key step in the mechanism of many phosphate transfer enzymes (kinases, phosphatases) and is the first stage in a wide variety of signal transduction cascades in bacteria, yeast, higher plants, and mammals. Studies of structural and dynamical aspects of such enzymes in the phosphorylated intermediate states are important for understanding the intimate molecular mechanisms of their functioning. Such information may be obtained via molecular dynamics and/or docking simulations, but in this case appropriate force field parameters for phosphohistidine should be explicitly defined. In the present article we describe development of the GROMOS96 force field parameters for phosphoimidazole molecule—a realistic model of the phosphohistidine side chain. The parameterization is based on the results of ab initio quantum chemical calculations with subsequent refinement and testing using molecular mechanics and molecular dynamics simulations. The set of force constants and equilibrium geometry is employed to derive force field for the phosphohistidine moiety. Resulting parameters and topology are incorporated into the molecular modeling package GROMACS and used in molecular dynamics simulations of a phosphohistidine‐containing protein in explicit solvent. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1313–1321, 2004
Cytokine‐induced cell death in human oligodendroglial cell lines. II: Alterations in gene expression induced by interferon‐γ and tumor necrosis factor‐α
Authors: Buntinx Mieke , Gielen Ellen , Van Hummelen Paul , Raus Jef , Ameloot Marcel , Steels Paul , Stinissen Piet
Published: May 2004

Cytokines, such as interferon‐γ (IFN‐γ) and tumor necrosis factor‐α (TNF‐α), can initiate dual effects resulting in either cell growth or cell death. In this study, the human oligodendroglial cell lines HOG and MO3.13 were used as a model to study the molecular mechanisms of cytokine‐induced cell death in human oligodendrocytes. We have previously shown that TNF‐α and IFN‐γ induce apoptosis in both oligodendroglial cell lines within 72 hr. In the present study, the cell death pathways operating within these cells were further investigated at the gene expression level. Both cell lines express a broad repertoire of caspases and apoptosis‐related genes. Some of these genes are specifically up‐regulated by cytokine treatment; e.g., caspase‐1 is up‐regulated by IFN‐γ. In addition to direct cytotoxic effects, IFN‐γ and TNF‐α also enhance the expression of Fas, TNFR1, and MHC class I molecules in both cell lines. This suggests that cytokines can make oligodendrocytes more vulnerable to different cell death pathways in an inflammatory environment. cDNA microarray analysis of the HOG cell line revealed that TNF‐α induces genes that regulate apoptosis, survival, inflammation, cell metabolism, and cell signaling. The data suggest that oligodendroglial cells activate both death and survival pathways upon cytokine challenges. However, the survival pathways seem to be unable to compete with the death signal after more than 24 hr of cytokine treatment. These results may contribute to the development of therapeutic strategies aimed at interfering with cytokine‐induced cell death of oligodendrocytes in patients with multiple sclerosis. © 2004 Wiley‐Liss, Inc.
Alpha‐dystroglycan interactions affect cerebellar granule neuron migration
Authors: Qu Qiang , Smith Frances I.
Published: May 2004

The interaction of alpha‐dystroglycan (a‐DG) with its extracellular binding partners requires glycans attached to its mucin core domain, and defects in the glycosylation of a‐DG are associated with both muscular dystrophy and neuronal migration defects. The involvement of a‐DG and one of its ligands, agrin, in cerebellar neuronal migration was investigated. Antibodies directed against glycosylated a‐DG inhibited granule neuron migration in cerebellar slice cultures. a‐DG interactions did not appear to influence neurite outgrowth in cerebellar explant cultures, but enhanced granule neuron binding was observed on cells transfected with a‐DG. These results suggest that interactions involving a‐DG influence the strength of attachment of granule neurons to the a‐DG‐expressing Bergmann glial cells that guide granule neuron migration in the cerebellum. Experiments using anti‐agrin antibodies suggest that agrin is not involved in these interactions. © 2004 Wiley‐Liss, Inc.
Activation and Polymerisation of ansa‐Zirconocene Chloroamido Complexes
Authors: Seraidaris Tanja , Löfgren Barbro , Mäkelä‐Vaarne Nora , Lehmus Petri , Stehling Udo
Published: May 2004

Summary: Propene polymerisation was conducted with three ansa‐zirconocene complexed: Me2Si(2‐Me‐4‐PhInd)2ZrCl2 (A), Me2Si(2‐Me‐4‐PhInd)2ZrClNMe2 (B) and Me2Si(2‐Me‐4‐PhInd)2ZrClNEt2 (C). Methylalumoxane (MAO) or [HNPhMe2][B(C6F5)4] was used as cocatalyst. The influence of cocatalysts and triisobutylaluminum (TIBA) on polymerisation activity, molecular weight and polymer microstructure was studied. Furthermore, the alkylation and activation of the complexes were examined using UV/VIS spectroscopy. Complex A was the most active in polymerisation, but polymers produced by B and C had in general higher molecular weights. Replacing MAO partially by TIBA increased the molecular weight and prevented catalyst deactivation. According to the UV/VIS measurements, all complexes have low reactivity towards TMA and TIBA. Similar cationic species were formed of all three studied zirconocenes in the reaction with MAO. Additional TIBA did not affect the type of active species formed in the reaction of zirconocene and MAO, but increased the activity of B and C.

UV/VIS spectrum of complex A with MAO and with a MAO/TIBA mixture.

image

UV/VIS spectrum of complex A with MAO and with a MAO/TIBA mixture.
Role of ulnar forearm free flap in oromandibular reconstruction
Authors: Gabr E.M. , Kobayashi M.R. , Salibian A.H. , Armstrong W.B. , Sundine M. , Calvert J.W. , Evans G.R.D.
Published: May 2004

The ulnar forearm flap is not frequently utilized for oromandibular reconstruction. This study evaluated the usefulness of the ulnar free flap for reconstruction. A retrospective study of 32 patients was conducted. The ulnar forearm flap was combined with an osseous flap in 24 patients. Nine females and 23 males with a mean age of 58.15 years comprised our study population. Squamous‐cell carcinoma was the diagnosis in 93.75% of cases (56.25% T4), of which 20% were recurrent. Functional evaluation of swallowing was based on the University of Washington Questionnaire (UWQ). The mean hospital stay was 9.8 days. The external carotid (100%) was the recipient artery, and the internal jugular (74.07%) was the main recipient vein. Overall flap survival was 96.8%. One flap was lost due to unsalvageable venous thrombosis. Major local complications were seen in 9.4% of cases and included partial flap loss, hematoma, and an orocutaneous fistula. At the time of this study, 21 patients were available for functional evaluation. Speech was rated excellent and good in 33.3% of patients. Swallowing was found good in 28.6% of patients. Chewing was rated excellent and good in 47.6% of patients. Cosmetic acceptance was rated good in 71.4% of cases. The ulnar forearm is a useful free flap in oromandibular reconstruction. It is available when the radial artery is the dominant artery of the hand. Being more hidden, it may be more cosmetically accepted. It affords pliable soft tissue for lining and/or covering of oromandibular defects, and can be used as a second choice after other free‐flap failures. © 2004 Wiley‐Liss, Inc.
On the solution of an initial‐boundary value problem that combines Neumann and integral condition for the wave equation
Authors: Dehghan Mehdi
Published: May 2004

Numerical solution of hyperbolic partial differential equation with an integral condition continues to be a major research area with widespread applications in modern physics and technology. Many physical phenomena are modeled by nonclassical hyperbolic boundary value problems with nonlocal boundary conditions. In place of the classical specification of boundary data, we impose a nonlocal boundary condition. Partial differential equations with nonlocal boundary specifications have received much attention in last 20 years. However, most of the articles were directed to the second‐order parabolic equation, particularly to heat conduction equation. We will deal here with new type of nonlocal boundary value problem that is the solution of hyperbolic partial differential equations with nonlocal boundary specifications. These nonlocal conditions arise mainly when the data on the boundary can not be measured directly. Several finite difference methods have been proposed for the numerical solution of this one‐dimensional nonclassic boundary value problem. These computational techniques are compared using the largest error terms in the resulting modified equivalent partial differential equation. Numerical results supporting theoretical expectations are given. Restrictions on using higher order computational techniques for the studied problem are discussed. Suitable references on various physical applications and the theoretical aspects of solutions are introduced at the end of this article. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005
Discrete compactness property for quadrilateral finite element spaces
Authors: Gardini Francesca
Published: May 2004

The main purpose of the present article is to prove the discrete compactness property for Arnold‐Boffi‐Falk spaces of any order. Results of numerical experiments confirming the theory are also reported. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005
4S neuroblastoma: The long‐term outcome
Authors: Levitt G.A. , Platt K.A. , De Byrne R. , Sebire N. , Owens C.M.
Published: May 2004

Background

Stage 4S neuroblastoma is associated with a high rate of spontaneous maturation and involution, with survival rates of 70–90%. There is little long‐term follow‐up data describing the disease status or late effects. The aim of this study was to assess the clinical outcome and imaging findings in long‐term survivors of 4S neuroblastoma.

Methods

The patient population was identified from a single centre over 26 years. Twenty‐five of 31 consecutive patients were long‐term survivors. Five died from disease progression and one from cerebral palsy related complications. All survivors underwent clinical examination. Abdominal ultrasound scanning, liver function tests, hepatitis viral screen, and urinary catecholamines were performed.

Results

The mean age at diagnosis was 8 ± 9 weeks with a mean age when studied of 11 years and 10 months ± 8 years. Twenty of 25 had no significant clinical findings, three had disease associated clinical abnormalities (neurological, multiple subcutaneous nodules). Three patients had treatment related effects (small testes, urethral stricture, radiation induced soft tissue hypoplasia, post‐surgical Horners syndrome). Persistant adrenal enlargement and calcification was noted in three patients. Twelve patients had abnormal liver ultrasound findings ranging from mildly coarse echotexture to structural changes without evidence of hepatic dysfunction or infection. Treatment did not correlate with abnormal hepatic ultrasound findings.

Conclusions

The majority of long‐term survivors of stage 4S neuroblastoma have no clinically or radiologically significant sequelae but do have residual abnormalities. These findings have implications for subsequent management of unrelated medical conditions in this patient group. © 2004 Wiley‐Liss, Inc.
A survey of clinical productivity and current procedural terminology (CPT) coding patterns of pediatric hematologist/oncologists
Authors: Griffin Timothy C. , Hutter John J. , Johnson Kimberly K. , Moscow Jeffrey A.
Published: May 2004

Background

Subspecialty‐specific normative values for clinical productivity of practicing pediatric hematologist/oncologists have not been well established. This information could be a useful adjunct in administrative decision‐making in areas such as necessary levels of physician staffing and development of compensation plans.

Methods

Current procedural terminology (CPT) coding information was obtained from 27 pediatric hematology/oncology groups. Clinical productivity was assessed by overall number of patient encounters and the total number of physician work relative value units (RVU) as defined by the resource‐based relative value scale. The average physician productivity within each individual program was calculated. To determine uniformity of CPT coding, an additional survey solicited mock patient encounter documentation and CPT coding for a simple clinical vignette.

Results

A broad range of clinical productivity was observed for both numbers of patient encounters and RVU. Evaluation of the CPT coding data of the surveyed groups revealed differences in usage of certain evaluation and management (E/M) codes and procedural and specimen interpretation codes. Within individual categories of E/M service codes, a wide variation in assigned CPT code levels was also observed. This observation was supported by differences in the E/M coding for the clinical vignette.

Conclusions

Assessment and tracking of physician productivity can provide useful information for the administrative management of pediatric hematology/oncology programs. Caution must be exercised, however, when making productivity comparisons with other subspecialties or even between pediatric hematology/oncology programs. Such comparisons should take into account the number of patient encounters, characteristics of E/M coding patterns, the use of physician extenders, as well as overall RVU production. © 2004 Wiley‐Liss, Inc.
Synthesis of pH‐sensitive surfactants by the terpolymerization of methacrylic acid, methoxy poly(ethylene glycol) methacrylate, and lauryl methacrylate: Initiator effect and reactivity ratio study
Authors: Restrepo A. Sabrina , Pinzón Neissa M. , Ju Lu‐Kwang
Published: May 2004

For the development of pH‐sensitive surfactants to be used in water‐in‐oil fermentation, the free‐radical terpolymerization of methacrylic acid (MAA), methoxy poly(ethylene glycol) methacrylate (MPEGMA), and lauryl methacrylate (LMA), at a molar ratio of 1.0:0.04:0.76, was studied with two initiators, azobisisobutyronitrile (AIBN) and hydrogen peroxide, at different concentrations. The polymer synthesized with 0.45% AIBN as the initiator was the most promising, giving similar conversions of all three monomers throughout the 10‐h polymerization. The subsequent study on AIBN‐initiated systems indicated that MPEGMA caused an increase‐then‐decrease profile of the MAA conversion with a plateau around an ethylene glycol/MAA ratio of 1–2. This observation was fairly consistent with the well‐known type II template polymerization of poly(ethylene glycol) (PEG)–MAA systems. The reactivity ratios obtained in this study suggested that the polymer synthesized with AIBN as the initiator had a structure of alternating blocks of MAA and LMA, with isolated PEG grafts. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2950–2959, 2004
New series of highly phenyl‐substituted polyfluorene derivatives for polymer light‐emitting diodes
Authors: Peng Qiang , Xie Minggui , Huang Yan , Lu Zhiyun , Xiao Dan
Published: May 2004

A new series of highly phenyl‐substituted polyfluorene derivatives were synthesized and characterized. The resulting polymers were amorphous and showed excellent solubility in common organic solvents, such as chloroform, tetrahydrofuran, xylene, toluene, chlorobenzene, and so forth. All possessed satisfied thermal stability with glass‐transition temperatures (Tg's) in the range of 79–115 °C. They emitted blue light with photoluminescent (PL) maximum peaks at about 408–412 nm in thin films. The PL efficiencies of the polymer films were measured around 30–33%. The highly phenylated pendants improved the Tg of polyfluorene without forming defects in the polymers and reduced their tendency to form aggregate/excimers. Polymer light‐emitting diodes were fabricated from these polymers with the configuration of indium tin oxide/polyethylenedioxythiophene:polystyrene sulfonic acid/polymer/Ba/Al, which emitted bright blue light with maximum peaks at 418–420 nm. The maximum external quantum efficiencies of these devices were 0.41–0.6%. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2985–2993, 2004
Side‐chain functionalized polymers containing bipyridine coordination sites: Polymerization and metal‐coordination studies
Authors: Carlise Joseph R. , Weck Marcus
Published: May 2004

Monomers containing (trisbipyridine) ruthenium(II), (bisbipyridine) palladium(II), and heteroleptic ruthenium complexes were synthesized and polymerized via ruthenium‐catalyzed ring‐opening metathesis polymerization in nonpolar solvents. The solubility of the resulting polyelectrolytes in nonpolar solutions could be tuned by alkyl functionalization of the ligands around the metal centers. These polymers are the first polynorbornenes containing a 2,2′‐bipyridine‐based metal complex at each repeating unit and might be used in numerous applications, including luminescent and electroluminescent materials. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2973–2984, 2004
Living cationic polymerization of vinyl ethers with a urethane group
Authors: Namikoshi Takeshi , Hashimoto Tamotsu , Kodaira Toshiyuki
Published: May 2004

To study the possibility of living cationic polymerization of vinyl ethers with a urethane group, 4‐vinyloxybutyl n‐butylcarbamate (1) and 4‐vinyloxybutyl phenylcarbamate (2) were polymerized with the hydrogen chloride/zinc chloride initiating system in methylene chloride solvent at −30 °C ([monomer]0 = 0.30 M, [HCl]0/[ZnCl2]0 = 5.0/2.0 mM). The polymerization of 1 was very slow and gave only low‐molecular‐weight polymers with a number‐average molecular weight (Mn) of about 2000 even at 100% monomer conversion. The structural analysis of the products showed occurrence of chain‐transfer reactions because of the urethane group of monomer 1. In contrast, the polymerization of vinyl ether 2 proceeded much faster than 1 and led to high‐molecular‐weight polymers with narrow molecular weight distributions (MWDs ≤ ∼1.2) in quantitative yield. The Mn's of the product polymers increased in direct proportion to monomer conversion and continued to increase linearly after sequential addition of a fresh monomer feed to the almost completely polymerized reaction mixture, whereas the MWDs of the polymers remained narrow. These results indicated the formation of living polymer from vinyl ether 2. The difference of living nature between monomers 1 and 2 was attributable to the difference of the electron‐withdrawing power of the carbamate substituents, namely, n‐butyl for 1 versus phenyl for 2, of the monomers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2960–2972, 2004
Monomer reactivity ratios for acrylonitrile–methyl acrylate free‐radical copolymerization
Authors: Wiles K. B. , Bhanu V. A. , Pasquale A. J. , Long T. E. , McGrath J. E.
Published: May 2004

Nonlinear monomer reactivity ratios for the homogeneous free‐radical copolymerization of acrylonitrile and methyl acrylate were determined from 1H NMR and real‐time Fourier transform infrared (FTIR) analyses. All 1H NMR data were obtained on polymers isolated at low conversions (<10%), whereas the FTIR data were collected in situ. The copolymerizations were conducted in N,N‐dimethylformamide at 62 °C and were initiated with azobisisobutyronitrile. The real‐time FTIR technique allowed for many data points to be collected for each feed composition, which enabled the calculation of copolymer compositions (dM1/dM2) with better accuracy. Monomer reactivity ratios were estimated with the Mayo–Lewis method and then were refined via a nonlinear least‐squares analysis first suggested by Mortimer and Tidwell. Thus, monomer reactivity ratios at the 95% confidence level were determined to be 1.29 ± 0.2 and 0.96 ± 0.2 for acrylonitrile and methyl acrylate, respectively, which were valid under the specific system conditions (i.e., solvent and temperature) studied. The results are useful for the development of acrylonitrile (<90%) and methyl acrylate, melt‐processable copolymer fibers and films, including precursors for carbon fibers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2994–3001, 2004
QCD‐like gauge dynamics from gravity duals
Authors: Evans N.
Published: May 2004

We describe attempts to study QCD‐like gauge dynamics using a deformed version of the AdS/CFT Correspondence. The Yang Mills* geometry is dual to a gauge theory that is non‐supersymmetric Yang Mills in the infra‐red but reverts to N = 4 super Yang Mills in the ultra‐violet. The geometry describes a discrete, calculable glueball spectrum with a mass gap. Wilson loops in the geometry display QCD string breaking.
A gravity dual of chiral symmetry breaking
Authors: Babington J. , Erdmenger J. , Evans N. , Guralnik Z. , Kirsch I.
Published: May 2004

We establish a holographic description of chiral symmetry breaking for a particular confining large N non‐supersymmetric gauge theory with matter in the fundamental representation. The gravity dual of this theory is obtained by introducing a D7‐brane probe into a deformed Anti‐de Sitter background found by Constable and Myers. We numerically compute the $\bar\psi\psi$ condensate and meson spectrum by solving the equation of motion of the D7‐brane probe in this background. We find a symmetry breaking condensate as well as the associated, pion‐like, Goldstone boson in the limit of small quark mass. The existence of the condensate ensures that the D7‐brane never reaches the naked singularity at the origin of the deformed AdS space.
UV/IR mixing, noncommutative instabilites and closed strings
Authors: López E.
Published: May 2004

The leading UV/IR mixing effects on noncommutative field theories modify the dispersion relations and, depending on their sign, may cause the appearance of unstable modes. For noncommutative gauge theories on D‐branes, this phenomenon is able to capture important information about the closed string spectrum of the parent string theory. We analyse noncommutative D‐branes on nonsupersymmetric orbifolds and twisted circle backgrounds. We find that the sign of the leading UV/IR mixing effects is governed by the mass gap between the lowest modes in the NSNS and RR closed string towers. For noncommutative D3‐branes at orbifolds we obtain a stronger result: a one to one correspondence between noncommutative instabilities and closed string tachyons.
Twisted determinants and bosonic open strings in an electromagnetic field
Authors: Russo R. , Sciuto S.
Published: May 2004

The bosonization equivalence between the 2–dimensional Dirac and Laplacian operators can be used to derive new interesting identities involving Theta functions. We use these formulae to compute the multiloop partition function of the bosonic open string in presence of a constant electromagnetic field.
Gauge instantons from open strings
Authors: Frau M. , Lerda A.
Published: May 2004

In this contribution we describe how to obtain instanton effects in four dimensional gauge theories by computing string scattering amplitudes in D3/D(‐1) brane systems. In particular we show that the disks with mixed boundary conditions, which are typical of the D3/D(‐1) system, are the sources for the classical instanton solution.
Special‐holonomy manifolds and quartic‐curvature string corrections
Authors: Stelle K.S.
Published: May 2004

The quartic‐curvature corrections derived from string theory have a very specific impact on the geometry of target‐space manifolds of special holonomy. In the cases of Calabi‐Yau manifolds and D = 7 manifolds of G2 holonomy, we show how the corrections conspire to preserve the unbroken supersymmetry of these backgrounds.
Vibrating sample magnetometer using a multilayer piezoelectric actuator
Authors: Shin K. H. , Park K. I. , Kim Y. , Sa‐Gong G.
Published: May 2004

A vibrating sample magnetometer with a multilayer piezoelectric actuator as vibrating mechanism is proposed in this paper. The piezoelectric vibrating mechanism was adopted to achieve both high sensitivity and small‐sizing of VSM. By applying an alternating voltage to the multilayer piezoelectric actuator, the quartz cantilever is vibrated transversely. The magnetic specimen on the end of the cantilever was vibrated ∼3.5 mm at 79 Hz. The proposed VSM has high sensitivity due to an extremely large vibrating amplitude and small size (30 × 25 × 25 cm3). (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear resonant magneto‐optical effects in alkaline metal vapors in the strong bichromatic laser radiation field
Authors: Karagodova T. Ya. , Kuptsova A. V.
Published: May 2004

Results of computer simulations of the spectra of magneto‐optical rotation (MOR) of the polarization plane for both components of intense bichromatic laser radiation are presented. Dependences of MOR on light intensity and the external magnetic field strength have been investigated. The simulations are based on the theory and method published earlier. Our results coincide with experimental results known from literature. This suggests that new peculiarities of MOR in alkaline vapors obtained by computer simulations can be observed in the natural experiments. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004