bluuebunny/crossref_metadata_2025 huggingface dataset:
Fiber‐optic sensor active networking with distributed erbium‐doped fiber and Raman amplification
Authors: Diaz S. , Abad S. , Lopez‐Amo M.
Published: November 2008

This work is meant to provide a review of different multiplexing topologies employing distributed erbium‐doped fiber and Raman amplification to solve the problem of power‐loss compensation in fiber‐optic sensor (FOS) networks. This is a key parameter in large multiplexing networks, particularly when employing intensity‐modulated sensors. These topologies are studied both theoretically and experimentally, and a comparative analysis is carried out between them. The main parameters considered in the analysis are power budget, optical signal‐to‐noise ratios, scalability and architecture complexity.
Transplantation-Mediated Alloimmune Thrombocytopenia: Guidelines for Utilization of Thrombocytopenic Donors
Authors: Diaz Geraldine C. , Prowda Joan , Lo Irene J. , Arepally Gowthami M. , Evans Neal , Wheeless Yvonne , Samstein Benjamin , Guarrera James V. , Renz John F.
Published: November 2008

Transplantation-mediated alloimmune thrombocytopenia (TMAT) is donor-derived thrombocytopenia following solid-organ transplantation. To date, no clear consensus on the appropriateness of organ utilization from cadaver donors with a history of idiopathic thrombocytopenia purpura (ITP) has emerged. Herein is reported a devastating case of TMAT following liver transplantation utilizing an allograft from a donor with ITP that resulted in allograft failure. The literature is reviewed in this context to propose preliminary guidelines regarding utilization of allografts from cadaver donors with a history of ITP.
Prevalence of Coronary Artery Calcification in Patients Undergoing Assessment for Orthotopic Liver Transplantation
Authors: McAvoy Norma C. , Kochar Narendra , McKillop Graham , Newby David E. , Hayes Peter C.
Published: November 2008

Patients with advanced liver disease are at increased risk of cardiovascular events, especially following orthotopic liver transplantation (OLT). Coronary artery calcification (CAC) is a novel and independent predictor of cardiovascular risk, but its prevalence and utility in patients with cirrhosis are unknown. The aim of this study was to define the prevalence of CAC and its association with markers of disease severity and standard measures of cardiovascular risk in a large cohort of patients undergoing OLT assessment. A single-center, prospective, observational study of 147 consecutive patients undergoing assessment for OLT was performed. CAC scores were derived with the Agatston method from thoracic computed tomography scans and correlated with cardiovascular risk factors and measures of liver disease severity. There were 101 patients (66 males) with a mean age of 53.2 years; 46 patients were excluded because the CAC score was not reported. The median CAC score was 40 HU (range, 0-3533). Correlations were identified between the CAC score and age (

r

= 0.477;

P

< 0.001), male sex (

r

= 0.262;

P

= 0.008), family history of cardiovascular disease (

r

= 0.208;

P

= 0.036), Framingham risk score (

r

= 0.621;

P

< 0.001), Model for End-Stage Liver Disease score (

r

= 0.221;

P

= 0.027), systolic blood pressure (

r

= 0.285;

P

= 0.004), diastolic blood pressure (

r

= 0.267;

P

= 0.007), cytomegalovirus status (

r

= 0.278;

P

= 0.005), fasting glucose (

r

= 0.330;

P

= 0.001), number of coronary vessels involved (

r

= 0.899;

P

< 0.001), and components of the metabolic syndrome (

r

= 0.226;

P

= 0.026). After multivariate analysis, age, systolic blood pressure, fasting glucose, number of features of metabolic syndrome, and number of vessels involved remained significantly associated with CAC. In conclusion, this study identified a high prevalence of occult coronary artery disease in patients undergoing OLT assessment and identified a strong relationship between CAC scores and a limited number of specific cardiovascular risk factors. The usefulness of these factors in predicting perioperative and postoperative cardiovascular events in patients undergoing OLT requires prospective evaluation.
The Difference in the Fibrosis Progression of Recurrent Hepatitis C After Live Donor Liver Transplantation Versus Deceased Donor Liver Transplantation is Attributable to the Difference in Donor Age
Authors: Selzner Nazia , Girgrah Nigel , Lilly Les , Guindi Maha , Selzner Markus , Therapondos George , Adeyi Oyedele , McGilvray Ian , Cattral Mark , Greig Paul D. , Grant David , Levy Gary , Renner Eberhard L.
Published: November 2008

Hepatitis C recurs universally after liver transplantation (LT). Whether its progression differs after live donor liver transplantation (LDLT) and deceased donor liver transplantation (DDLT) is still debated. We retrospectively analyzed 201 consecutive LTs performed at our institution for hepatitis C–related end-stage liver disease between April 2000 and December 2005 (46 LDLTs and 155 DDLTs). Patients were followed with protocol biopsies for medians of 29 (LDLT) and 39 months (DDLT;

P

= 0.7). Although overall graft and patient survival did not differ, the mean fibrosis stage (Metavir) was significantly higher at 12 to 48 months post-LT (all

P

< 0.05), and the rate of fibrosis progression tended to be faster after DDLT than LDLT (0.19 versus 0.11 stage/year,

P

= 0.05). In univariate analysis, donor age, cold ischemic time, and DDLT were significantly associated with a fibrosis stage ≥ 1 at 1 year and a fibrosis stage of 3 or 4 at 2 years post-LT. In multivariate analysis, however, donor age was the sole variable independently associated with both surrogate outcomes. Thus, donor age > 45 years carried a relative risk of 8.17 (confidence interval = 2.6–25.5,

P

= 0.001) for reaching fibrosis stage 3 or 4 at 2 years post-LT. In conclusion, donor age, rather than the transplant approach, determines the progression of recurrent hepatitis C after LT. LDLT, allowing for the selection of younger donors, may particularly benefit hepatitis C patients.
Biliary Reconstruction for Infantile Living Donor Liver Transplantation: Roux-en-Y Hepaticojejunostomy or Duct-to-Duct Choledochocholedochostomy?
Authors: Shirouzu Yasumasa , Okajima Hideaki , Ogata Satsuki , Ohya Yuki , Tsukamoto Yukika , Yamamoto Hidekazu , Takeichi Takayuki , Kwang-Jong Lee , Asonuma Katsuhiro , Inomata Yukihiro
Published: November 2008

Hepaticojejunostomy is a standard biliary reconstruction method for infantile living donor liver transplantation (LDLT), but choledochocholedochostomy for infants is not generally accepted yet. Ten pediatric recipients weighing no more than 10 kg underwent duct-to-duct choledochocholedochostomy (DD) for biliary reconstruction for LDLT. Patients were followed up for a median period of 26.8 months (range: 4.0–79.0 months). The incidence of posttransplant biliary complications for DD was compared with that for Roux-en-Y hepaticojejunostomy (RY). No DD patients and 1 RY patient (5%) developed biliary leakage (

P

> 0.05), and biliary stricture occurred in 1 DD patient (10%) and none of the RY patients (

P

> 0.05); none of the DD patients and 5 RY patients (25%) suffered from uncomplicated cholangitis after LDLT (

P

> 0.05), and 1 DD patient (10%) and 2 RY patients (10%) died of causes unrelated to biliary complications. In conclusion, both hepaticojejunostomy and choledochocholedochostomy resulted in satisfactory outcome in terms of biliary complications, including leakage and stricture, for recipients weighing no more than 10 kg.
Comparison of a New Enzymatic Assay with a High-Performance Liquid Chromatography/Ultraviolet Detection Method for Therapeutic Drug Monitoring of Mycophenolic Acid in Adult Liver Transplant Recipients
Authors: Blanchet Benoit , Taieb Fabrice , Conti Filomena , Abbas Halim , Seydi Idrissa , Harcouet Laura , Dauphin Alain , Calmus Yvon , Tod Michel
Published: November 2008

Mycophenolic acid (MPA) is used to prevent graft rejection. The methods used for determining the plasma MPA concentration in liver transplant recipients are the enzyme-multiplied immunoassay technique (EMIT), high-performance liquid chromatography with ultraviolet detection (HPLC-UV), and most recently mass spectrometry. EMIT has been reported to overestimate the MPA concentration by 30% to 35% in comparison with HPLC-UV. Recently, a new automated enzymatic assay based on inosine monophosphate dehydrogenase inhibition has been designed. The aim of the present investigation was to compare this technique with validated HPLC-UV in adult liver transplant recipients treated with tacrolimus or cyclosporine. One hundred seventy-six samples from 50 adult liver transplant recipients were analyzed with both techniques. Patients received mycophenolate mofetil (2 or 3 times daily) coadministered with cyclosporine microemulsion (n = 18) or tacrolimus (n = 32). Samples were drawn over an interdose interval during the early or late posttransplantation period. The Passing-Bablok regression and Bland-Altman plot were used to compare the 2 techniques. The Passing-Bablock regression, calculated from 166 samples, showed very good agreement between the enzymatic assay and the HPLC-UV method: enzymatic assay = 1.0204 (95% confidence interval, 0.9942, 1.0478) × HPLC-UV + 0.0201 (−0.0442, 0.0882). No significant bias was found between the techniques (Bland-Altman plot), and the median relative difference was 2.7% (95% confidence interval, −0.4, 6.6). In conclusion, the enzymatic assay showed an excellent correlation with HPLC-UV. Therefore, this method was proved valid and reliable for the monitoring of the plasma MPA concentration in adult liver transplant recipients treated with cyclosporine microemulsion or tacrolimus.
The Potential Impact of Using Donations After Cardiac Death on the Liver Transplantation Program and Waiting List in the State of Sao Paulo, Brazil
Authors: Chaib Eleazar , Massad Eduardo
Published: November 2008

Liver transplantation was first performed at the University of Sao Paulo School of Medicine in 1968. Since then, the patient waiting list for liver transplantation has increased at a rate of 150 new cases per month. Liver transplantation itself rose 1.84-fold (from 160 to 295) from 1988 to 2004. However, the number of patients on the liver waiting list jumped 2.71-fold (from 553 to 1500). Consequently, the number of deaths on the liver waiting list moved to a higher level, from 321 to 671, increasing 2.09-fold. We have applied a mathematical model to analyze the potential impact of using a donation after cardiac death (DCD) policy on our liver transplantation program and on the waiting list. Five thousand one hundred people died because of accidents and other violent causes in our state in 2004; of these, only 295 were donors of liver grafts that were transplanted. The model assumed that 5% of these grafts would have been DCD. We found a relative reduction of 27% in the size of the liver transplantation waiting list if DCD had been used by assuming that 248 additional liver transplants would have been performed annually. In conclusion, the use of DCD in our transplantation program would reduce the pressure on our liver transplantation waiting list, reducing it by at least 27%. On the basis of this model, the projected number of averted deaths is about 41,487 in the next 20 years.
Tezosentan, a Novel Endothelin Receptor Antagonist, Markedly Reduces Rat Hepatic Ischemia and Reperfusion Injury in Three Different Models
Authors: Farmer Douglas G. , Kaldas Fady , Anselmo Dean , Katori Masamichi , Shen Xiu-Da , Lassman Charles , Kaldas Marian , Clozel Martine , Busuttil Ronald W. , Kupiec-Weglinski Jerzy
Published: November 2008

This study investigated the effects of dual endothelin (ET) receptor blockade in rat models of liver ischemia and reperfusion injury (IRI). Three models of IRI were used: (1)

in vivo

total hepatic warm ischemia with portal shunting for 60 minutes with control (saline) and treatment groups (15 mg/kg tezosentan intravenously prior to reperfusion), (2)

ex vivo

hepatic perfusion after 24 hours of cold storage in University of Wisconsin solution with control and treatment groups (10 mg/kg tezosentan in the perfusate), and (3) syngeneic liver transplantation (LT) after 24 hours of cold storage in University of Wisconsin solution with control and treatment groups (10 mg/kg tezosentan intravenously prior to reperfusion). Tezosentan treatment significantly improved serum transaminase and histology after IRI in all 3 models. This correlated with reduced vascular resistance, improved bile production, and an improved oxygen extraction ratio. Treatment led to a reduction in neutrophil infiltration and interleukin-1 beta and macrophage inflammatory protein 2 production. A reduction in endothelial cell injury as measured by purine nucleoside phosphorylase was seen. Survival after LT was significantly increased with tezosentan treatment (90% versus 50%). In conclusion, this is the first investigation to examine dual receptor ET blockade in 3 models of hepatic IRI and the first to use the parenterally administered agent tezosentan. The results demonstrate that in both warm and cold IRI tezosentan administration improves sinusoidal hemodynamics and is associated with improved tissue oxygenation and reduced endothelial cell damage. In addition, reduced tissue inflammation, injury, and leukocyte chemotactic signaling were seen. These results provide compelling data for the further investigation of the use of tezosentan in hepatic IRI.
Hydroxyethyl Starch–Based Preservation Solutions Enhance Gene Therapy Vector Delivery Under Hypothermic Conditions
Authors: Henry Scot D. , van der Wegen Pascal , Metselaar Herold J. , Scholte Bob J. , Tilanus Hugo W. , van der Laan Luc J. W.
Published: November 2008

Isolated liver perfusion offers a unique prospect for safe, effective targeting of gene therapies that can be directed against allograft rejection or recurrent diseases such as reinfection by hepatitis C virus (HCV). We aimed to examine the effect of organ preservation solutions on vector-based gene therapy delivery under hypothermic conditions. University of Wisconsin (UW) solution, histidine tryptophan ketoglutarate (HTK), EloHaes, sodium-poly(ethylene glycol)-UW solution [Institut Georges Lopez 1 solution (IGL-1)], and Dulbecco's modified Eagle's medium (DMEM) culture medium (control) were tested at 2°C or 37°C for lentiviral vector transduction efficiencies to the hepatoma cell line Huh-7 and primary human or mouse hepatocytes. Lentiviral vectors expressing short hairpin RNA were used to target HCV replication. With a potent short hairpin RNA vector, transductions were directly correlated to the therapeutic effect, with low transduction yielding low knockdown and vice versa. Green fluorescent protein (GFP) reporter gene expression was observed with vector incubation times as short as 10 minutes. The highest transductions were seen, after 2-hour 37°C incubation, in UW (62% ± 6 SEM); they were significantly higher than those in HTK (21% ± 7 SEM). Neither adenosine nor glutathione, present in UW, provided any increase in transduction when supplemented to HTK, although the addition of hydroxyethyl starch (HES) significantly improved transductions. To rule out size exclusion as a mechanism of HES, IGL-1 was tested but did not result in better transductions than HTK or DMEM. When supplemented to UW, anionic compounds reduced transduction, and this indicated a charge interaction mechanism of HES. In conclusion, this study demonstrates that effective vector delivery can be achieved under conditions of hypothermic liver perfusion. UW provides superior transduction to hepatocytes over nonstarch solutions.
Report of the Paris Consensus Meeting on Expanded Criteria Donors in Liver Transplantation
Authors: Durand François , Renz John F. , Alkofer Barbara , Burra Patrizia , Clavien Pierre-Alain , Porte Robert J. , Freeman Richard B. , Belghiti Jacques
Published: November 2008

Because of organ shortage and a constant imbalance between available organs and candidates for liver transplantation, expanded criteria donors are needed. Experience shows that there are wide variations in the definitions, selection criteria, and use of expanded criteria donors according to different geographic areas and different centers. Overall, selection criteria for donors have tended to be relaxed in recent years. Consensus recommendations are needed. This article reports the conclusions of a consensus meeting held in Paris in March 2007 with the contribution of experts from Europe, the United States, and Asia. Definitions of expanded criteria donors with respect to donor variables (including age, liver function tests, steatosis, infections, malignancies, and heart-beating versus non–heart-beating, among others) are proposed. It is emphasized that donor quality represents a continuum of risk rather than “good or bad.” A distinction is made between donor factors that generate increased risk of graft failure and factors independent of graft function, such as transmissible infectious disease or donor-derived malignancy, that may preclude a good outcome. Updated data concerning the risks associated with different donor variables in different recipient populations are given. Recommendations on how to safely expand donor selection criteria are proposed.
1H and 13C NMR assignments for two new cordiaquinones from roots of Cordia leucocephala
Authors: Diniz Jaécio Carlos , Viana Francisco Arnaldo , Oliveira Odaci Fernandes , Maciel Maria Aparecida M. , Torres Maria da Conceição de Menezes , Braz‐Filho Raimundo , Silveira Edilberto R. , Pessoa Otília Deusdênia L.
Published: November 2008

From the roots of Cordia leucocephala (Boraginaceae), two new meroterpenoid naphthoquinones, 6‐[10‐(12,12‐dimethyl‐13α‐hydroxy‐16‐methenyl‐cyclohexyl)ethyl]‐1,4‐naphthalenedione (cordiaquinone L) and 5‐methyl‐6‐[10‐(12,12‐dimethyl‐13β‐hydroxy‐16‐methenyl‐cyclohexyl)methyl‐1,4‐naphthalenedione (cordiaquinone M) were isolated. Their structures were elucidated after detailed 1D and 2D NMR (COSY, HSQC, HMBC and NOESY) data analyses and comparison with literature data for analogous compounds. Copyright © 2008 John Wiley & Sons, Ltd.
Complete multinuclear magnetic resonance characterization of a set of polyfluorinated acids and alcohols
Authors: Marchione Alexander A. , Buck Robert C.
Published: November 2008

A complete 1H, 19F, and 13C NMR assignment of a homologous series of polyfluorinated acids and alcohols is reported. These assignments were obtained chiefly through single and multiple‐bond 1H–13C and 19F–13C correlation experiments (HSQC, HMBC). 19F NOESY experiments were required for assignment of two compounds with diastereotopic 19F nuclei in the CF2chain of the molecule. Copyright © 2008 John Wiley & Sons, Ltd.
Labeling of human neural precursor cells using ferromagnetic nanoparticles
Authors: Focke Almut , Schwarz Sigrid , Foerschler Annette , Scheibe Johanna , Milosevic Javorina , Zimmer Claus , Schwarz Johannes
Published: November 2008

Fetal human neural precursor cells (NPCs) are unique with respect to their capacity to proliferate and to preserve their potential to differentiate into neurons and glia. Human mesencephalic neural precursor cells (hmNPCs) provide a source for dopaminergic neurons. Preclinical and clinical research will benefit from reliable in vivo tracking of transplanted cells. Here, we investigate the potency of very small superparamagnetic iron oxide particles (VSOPs) to label hmNPCs, the effect of VSOPs on survival, proliferation, and differentiation of hmNPCs, and the sensitivity of 1.5T magnetic resonance imaging (MRI) to detect labeled cells in living rats following transplantation. When incubated with VSOPs at 1.5 mM, >95% of hmNPCs incorporated VSOPs without detectable impact on cell viability (>90%) or proliferative capacity, as measured by the expression of proliferating cell nuclear antigen (PCNA) and cell cycle distribution. Labeled hmNPCs differentiate into neurons (>30%) and glia with no detectable difference compared to nonlabeled cells. Following transplantation into rat striata, marked paramagnetic signal changes were detected for as long as three months postsurgery using MRI, corresponding to the histologically‐identified graft. Our data indicate that hmNPCs can be labeled with VSOPs without impairment of viability, proliferation, or multipotency. Labeled, transplanted cells are detectable in vivo using 1.5T MRI. Magn Reson Med 60:1321–1328, 2008. © 2008 Wiley‐Liss, Inc.
Improved 3D phase contrast MRI with off‐resonance corrected dual echo VIPR
Authors: Johnson Kevin M. , Lum Darren P. , Turski Patrick A. , Block Walter F. , Mistretta Charles A. , Wieben Oliver
Published: November 2008

Phase contrast (PC) magnetic resonance imaging with a three‐dimensional, radially undersampled acquisition allows for the acquisition of high resolution angiograms and velocimetry in dramatically reduced scan times. However, such an acquisition is sensitive to blurring and artifacts from off‐resonance and trajectory errors. A dual‐echo trajectory is proposed with a novel trajectory calibration from prescan data coupled with a multi‐frequency reconstruction to correct for these errors. Comparisons of phantom data and in vivo results from volunteer, and patients with arteriovenous malformations patients are presented with and without these corrections and show significant improvement of image quality when both corrections are applied. The results demonstrate significantly improved visualization of vessels, allowing for highly accelerated PC acquisitions without sacrifice in image quality. Magn Reson Med 60:1329–1336, 2008. © 2008 Wiley‐Liss, Inc.
Three‐element phased‐array coil for imaging of rat spinal cord at 7T
Authors: Mogatadakala Kishore V. , Bankson James A. , Narayana Ponnada A.
Published: November 2008

To overcome some of the limitations of an implantable coil, including its invasive nature and limited spatial coverage, a three‐element phased‐array coil is described for high‐resolution magnetic resonance imaging (MRI) of rat spinal cord. This coil allows imaging both thoracic and cervical segments of rat spinal cord. In the current design, coupling between the nearest neighbors was minimized by overlapping the coil elements. A simple capacitive network was used for decoupling the next neighbor elements. The dimensions of individual coils in the array were determined based on the signal‐to‐noise ratio (SNR) measurements performed on a phantom with three different surface coils. SNR measurements on a phantom demonstrated higher SNR for the phased array coil relative to two different volume coils. In vivo images acquired on rat spinal cord with our coil demonstrated excellent gray and white matter contrast. To evaluate the performance of the phased array coil under parallel imaging, g‐factor maps were obtained for acceleration factors of 2 and 3. These simulations indicate that parallel imaging with an acceleration factor of 2 would be possible without significant image reconstruction–related noise amplifications. Magn Reson Med 60:1498–1505, 2008. © 2008 Wiley‐Liss, Inc.
In vivo “hot spot” MR imaging of neural stem cells using fluorinated nanoparticles
Authors: Ruiz‐Cabello Jesús , Walczak Piotr , Kedziorek Dorota A. , Chacko Vadappuram P. , Schmieder Anna H. , Wickline Samuel A. , Lanza Gregory M. , Bulte Jeff W.M.
Published: November 2008

To optimize 19F MR tracking of stem cells, we compared cellular internalization of cationic and anionic perfluoro‐15‐crown‐5‐ether (PFCE) nanoparticles using cell culture plates with different surface coatings. The viability and proliferation of anionic and cationic PFCE‐labeled neural stem cells (NSCs) did not differ from unlabeled cells. Cationic PFCE nanoparticles (19F T1/T2 = 580/536 ms at 9.4 Tesla) were superior to anionic particles for intracellular fluorination. Best results were obtained with modified polystyrene culture dishes coated with both carboxylic and amino groups rather than conventional carboxyl‐coated dishes. After injecting PFCE‐labeled NSCs into the striatum of mouse brain, cells were readily identified in vivo by 19F MRI without changes in signal or viability over a 2‐week period after grafting. These results demonstrate that neural stem cells can be efficiently fluorinated with cationic PFCE nanoparticles without using transfection agents and visualized in vivo over prolonged periods with an MR sensitivity of approximately 140 pmol of PFCE/cell. Magn Reson Med 60:1506–1511, 2008. © 2008 Wiley‐Liss, Inc.
Continuous flow‐driven inversion for arterial spin labeling using pulsed radio frequency and gradient fields
Authors: Dai Weiying , Garcia Dairon , de Bazelaire Cedric , Alsop David C.
Published: November 2008

Continuous labeling by flow‐driven adiabatic inversion is advantageous for arterial spin labeling (ASL) perfusion studies, but details of the implementation, including inefficiency, magnetization transfer, and limited support for continuous‐mode operation on clinical scanners, have restricted the benefits of this approach. Here a new approach to continuous labeling that employs rapidly repeated gradient and radio frequency (RF) pulses to achieve continuous labeling with high efficiency is characterized. The theoretical underpinnings, numerical simulations, and in vivo implementation of this pulsed continuous ASL (PCASL) method are described. In vivo PCASL labeling efficiency of 96% relative to continuous labeling with comparable labeling parameters far exceeded the 33% duty cycle of the PCASL RF pulses. Imaging at 3T with body coil transmission was readily achieved. This technique should help to realize the benefits of continuous labeling in clinical imagers. Magn Reson Med 60:1488–1497, 2008. © 2008 Wiley‐Liss, Inc.
Characterization of tumor angiogenesis with dynamic contrast‐enhanced MRI and biodegradable macromolecular contrast agents in mice
Authors: Feng Yi , Jeong Eun‐Kee , Mohs Aaron M. , Emerson Lyska , Lu Zheng‐Rong
Published: November 2008

The efficacy of polydisulfide‐based biodegradable macromolecular contrast agents for characterizing tumor angiogenesis was investigated in a mouse model using dynamic contrast‐enhanced MRI (DCE‐MRI). Biodegradable macromolecular MRI contrast agents, gadopentetate dimeglumine (Gd‐DTPA) cystamine copolymers (GDCC), and Gd‐DTPA cystine copolymers (GDCP), with molecular weights of 20 and 70 kDa were used in the study. Gadodiamide (Gd [DTPA‐BMA]) and albumin labeled with Gd‐DTPA [albumin‐(Gd‐DTPA)] were used as the controls. The DCE‐MRI studies were performed in nude mice bearing prostate tumor xenografts from the MDA‐PCa‐2b cell line. Tumor angiogenic kinetic parameters, including endothelial transfer coefficient (KPS), fractional tumor plasma volume (fPV), and permeability surface area product (PS), were estimated from the DCE‐MRI data using a two‐compartment model. The KPS and fPV values estimated by the biodegradable macromolecular contrast agents were between those estimated by Gd(DTPA‐BMA) and albumin‐(Gd‐DTPA). The parameters estimated by the agent with a slow degradation rate and high molecular weight, GDCP‐70 (KPS = 2.09 ± 0.50 ml/min/100 cc and fPV = 0.075 ± 0.021), were closer to those by albumin‐(Gd‐DTPA) (KPS = 1.43 ± 0.64 ml/min/100 cc and fPV = 0.044 ± 0.007) than by other agents with relatively low molecular weight or rapid degradation rate. The polydisulfide‐based biodegradable macromolecular contrast agents are promising for characterizing tumor vascularity and angiogenesis with DCE‐MRI. Magn Reson Med 60:1347–1352, 2008. © 2008 Wiley‐Liss, Inc.
Nanoparticle pharmacokinetic profiling in vivo using magnetic resonance imaging
Authors: Neubauer Anne M. , Sim Hoon , Winter Patrick M. , Caruthers Shelton D. , Williams Todd A. , Robertson J. David , Sept David , Lanza Gregory M. , Wickline Samuel A.
Published: November 2008

Contrast agents targeted to molecular markers of disease are currently being developed with the goal of identifying disease early and evaluating treatment effectiveness using noninvasive imaging modalities such as MRI. Pharmacokinetic profiling of the binding of targeted contrast agents, while theoretically possible with MRI, has thus far only been demonstrated with more sensitive imaging techniques. Paramagnetic liquid perfluorocarbon nanoparticles were formulated to target αvβ3‐integrins associated with early atherosclerosis in cholesterol‐fed rabbits to produce a measurable signal increase on magnetic resonance images after binding. In this work, we combine quantitative information of the in vivo binding of this agent over time obtained by means of MRI with blood sampling to derive pharmacokinetic parameters using simultaneous and individual fitting of the data to a three compartment model. A doubling of tissue exposure (or area under the curve) is obtained with targeted as compared to control nanoparticles, and key parameter differences are discovered that may aid in development of models for targeted drug delivery. Magn Reson Med 60:1353–1361, 2008. © 2008 Wiley‐Liss, Inc.
Perfusion Tensor Imaging
Authors: Frank Lawrence R. , Lu Kun , Wong Eric C.
Published: November 2008

Arterial spin labeling (ASL) provides a method by which to noninvasively measure the spatial and temporal characteristics of local tissue perfusion. Standard methods employ spatial tagging schemes, but recently methods based on velocity dependent tags, called Velocity Selective ASL (VSASL), have been introduced wherein the tagging depends upon the vascular velocity profile. In this article, we point out an interesting feature of VSASL: the velocity can be encoded in any direction, thereby allowing for the measurement of perfusion with a specified angular resolution. This then facilitates the reconstruction of the local perfusion field, characterized by a perfusion tensor P, from which can be derived quantities related to the structure of the local perfusion field, such as the mean perfusion, the perfusion anisotropy, and the principal directions of flow feeding each voxel. We demonstrate this new method, Perfusion Tensor Imaging (PTI), in both the brain and skeletal muscle of normal human volunteers and discuss possible applications. Magn Reson Med 60:1284–1291, 2008. © 2008 Wiley‐Liss, Inc.
Estimation of base settlement from the surface subsidence profile: Plane‐field of displacements
Authors: Baxevanis Theocharis , Plexousakis Michael
Published: November 2008

According to Litwiniszyn's theory, subsidence over a yielding underground geo‐structure is seen as a stochastic (Markov) process. This theory leads to a single, linear parabolic differential equation of diffusion–convection type (D–C equation) in the plane‐field of displacements. If the boundary conditions for the governing D–C equation are prescribed along the shear bands, i.e. at ‘moving’ boundaries—it has been observed from small‐scale model experiments that the subsiding process is always confined between a set of inclined shear bands—then the resulting equation is nonlinear. The inverse problem for this nonlinear equation, i.e. the problem of determining the base displacement using the surface subsidence as ‘initial’ condition, is ill‐posed and estimation of the base displacement from a given surface subsidence profile is not possible. In the present paper the domain of integration of the governing D–C equation is fixed (and bounded)—the boundaries are not evolving. Hence, the governing equation remains linear parabolic. The advantage is that this linear differential equation admits an analytical solution, under the trap‐door mechanism assumption, that enables a direct solution to the inverse problem. Copyright © 2008 John Wiley & Sons, Ltd.
Evaluation of pressor and visceromotor reflex responses to bladder distension in urethane anesthetized rats
Authors: Blatt Lauren K. , Lashinger Erin S.R. , Laping Nicholas J. , Su Xin
Published: November 2008

Aims

We tested cardiovascular and visceromotor reflex (VMR) responses to urinary bladder distension (UBD) in urethane anesthetized rats to see if it can replicate the response pattern and the inhibition of bladder nociceptive transmission by analgesics seen in isoflurane anesthetized animals.

Methods

Female Sprague‐Dawley rats under 3% isoflurane anesthesia were acutely instrumented with jugular venous, carotid arterial, and bladder cannulas for drug administration, blood pressure (BP) measurement, and bladder distension, respectively. Needle electrodes were placed directly into the abdominal musculature to measure myoelectrical activity subsequent to phasic UBD (30 sec in 3 min intervals). A cardiovascular response (pressor) and a VMR response (a contraction of abdominal and hind limb musculature) to UBD were evaluated in urethane (1.2 g/kg, i.v.) or isoflurane (1%) anesthetized rats.

Results

Pressor and VMR responses to noxious UBD (60 mmHg) were generated under both anesthesics. The thresholds of stimulus response functions for both pressor and VMR responses were not affected by either anesthesics. However, the magnitude of the maximal pressor response was significantly reduced in urethane anesthesia. The analgesics, morphine, and mexiletine, significantly inhibited the VMR response to noxious UBD under both anesthetics, but the intensities of the inhibition from both analgesics under urethane anesthesia were much lower than under isoflurane anesthesia (ID50: 2.07 mg/kg vs. 0.88 mg/kg for morphine, >10 mg/kg vs. 0.47 mg/kg for mexiletine).

Conclusions

The rat urinary bladder distension model in urethane anesthetized rats demonstrates a blunted maximal pressor response and a reduced inhibition of visceral nociceptive transmission by analgesics. Neurourol. Urodynam. 28:442–446, 2009. © 2008 Wiley‐Liss, Inc.
Effects of 17ββ‐estradiol on rat urinary bladder: Gender differences in anoxia–glucopenia and reperfusion damage
Authors: Valeri Aurora , Ceccarelli Ilaria , Fiorenzani Paolo , Aloisi Anna Maria , Sgaragli Giampietro , Pessina Federica
Published: November 2008

Aim

To study the effect of 17β‐estradiol (E2) as a neuroprotective agent in male and female rat urinary bladders subjected to Anoxia‐Glucopenia and Reperfusion (A/G‐R) damage.

Methods

Rat urinary bladders were exposed to 1 hour of A—G and 2 hours of reperfusion (R). Intrinsic nerves underwent electrical field stimulation. The effect of E2 on the contractile response and its recovery in R phase, was monitored by adding it to the bath medium, at different concentrations, 60 min before A—G, during the A—G and the first 30 min of R. Furthermore, on both genders, in vivo treatments with E2, testosterone, IC1 182,780 and anastrozole were performed.

Results

After A—G the recovery of the nerve function in female bladders were significantly higher than in male. E2 given both in vivo (increased of E2 plasma levels were monitored) and in vitro, resulted to be neuroprotective in male bladder subjected to A—G/R damage. When rats were treated with anastrozole, a lower recovery of nerve responses both in male and female bladders was observed. Finally, treatments with E2 receptor antagonist ICI 182,780 increased E2 plasma levels and showed to abolished E2 neuroprotection, thus suggesting that E2 promotes nelronal survival likely through a rapid estrogen receptor mediated response.

Conclusions

Male rat urinary bladder serves are more susceptible to A—G/R damage than female. E2 exhibits neuroprotective properties and could be a lead for novel agents capable to protect the urinary bladder from ischaemia/reperfusion damage associated with urinary bladder disorders. Neurourol. Urodyn. 28:535–541, 2009. © 2008 Wiley‐Liss, Inc.
Study of crystal structure of (polyvinylidene fluoride/clay) nanocomposite films: Effect of process conditions and clay type
Authors: Sadeghi Farhad , Ajji Abdellah
Published: November 2008

Three Polyvinylidene fluoride (PVDF) different in molecular structure were used to produce nanocomposities films by cast extrusion with a particular emphasis on maximizing the β crystal phase content. The PVDF/clay compounding followed by cast film production was carried out through melt extrusion using a twin screw extruder equipped with a slit die. X‐ray diffraction (XRD) results showed that clay melt intercalation is almost similar for all three PVDFs. The XRD results also revealed that nanocomposite films from PVDF with branched chain structure (PVDFB) generated the greatest amount of β phase. FTIR spectroscopy measurements confirmed the XRD results but also revealed that significant stretching of the melt films at the die or rapid cooling would adversely affect the formation of β phase. The amount of β phase obtained based on nanoclay compounding was compared with that obtained from conventional method: stretching of molded PVDF film with initial α phase. Stretching of PVDF film at 60°C yielded pure β phase that means complete transformation of α to β. From mechanical properties, tensile tests were carried out on PVDF nanocomposite films to evaluate mechanical strength. PVDF with low molecular weight exhibited a very low strain at break while branched PVDF and high molecular weight PVDF could sustain more strain. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers
Proximity and distance goals in adult attachment
Authors: Dewitte Marieke , De Houwer Jan
Published: November 2008

We used a variant of the Implicit Association Test (IAT) and explicit reports to examine the assumption that attachment anxiety and avoidance are related to proximity and distance goals. Results confirmed that attachment avoidance was associated with a stronger implicit motivation for and positive evaluation of distance goals in attachment relationships. This was found both at the implicit and explicit levels and both in a threat and non‐threat context. Attachment anxiety was associated with proximity goals only when measured explicitly, but not when goal activation was measured implicitly. Our findings highlight the importance of considering both implicit and explicit goal representations when studying motivational processes in the context of attachment, and suggest that the IAT can provide a useful tool for investigating implicit motivational constructs. Copyright © 2008 John Wiley & Sons, Ltd.
Synthesis and characterization of novel polyurethanes based on aminolysis of poly(ethylene terephthalate) wastes, and evaluation of their thermal and mechanical properties
Authors: Shamsi Ramin , Abdouss Majid , Sadeghi Gity Mir Mohamad , Taromi Faramarz Afshar
Published: November 2008

BACKGROUND: Much research is currently directed towards recycling post‐consumer poly(ethylene terephthalate) (PET) products for both environmental and economic reasons. Aminolysis of PET wastes using different amines, such as allylamine, morpholine, hydrazine and polyamines, leads to different reaction products as diamides of terephthalic acid, which do not possess any potential for further chemical reactions. In the past, the use of ethanolamine has been investigated for the aminolytic degradation of PET waste in the presence of different simple chemicals such as sodium acetate as catalysts. The product obtained, bis(2‐hydroxyethylene) terephthalamide (BHETA), has potential for further reactions to obtain useful products. Nevertheless, there has been no report on using recycled BHETA from PET to synthesize polyurethanes.

RESULTS: In this research the product of aminolysis of PET waste, BHETA, was prepared. Then novel polyurethanes were synthesized based on the BHETA prepared, 1,4‐butanediol, ether‐type polyol and various molar ratios of hexamethylene diisocyanate. To evaluate the effect of BHETA, the properties of the polyurethanes without and with BHETA were compared. Fourier transform infrared spectra, thermal transitions, degradation, swelling ratio and chemical resistance of the synthesized polyurethanes were investigated. Also, the polyurethanes were applied as adhesives on various substrates. Comparison of the maximum bond strength of the synthesized polyurethane to that of commercial adhesives shows an about 2.2‐fold increase.

CONCLUSION: It is possible to synthesize new polyurethanes with interesting properties using BHETA as an aminolysis product of PET waste. These kinds of materials have potential for many applications, such as adhesives and coatings. Copyright © 2008 Society of Chemical Industry
Copolymers of N‐alkyl‐ and N‐arylalkylacrylamides with acrylamide: influence of hydrophobic structure on associative properties. Part II: rheological behaviour in semi‐dilute solution
Authors: Camail Michel , Margaillan André , Martin Isabelle
Published: November 2008

BACKGROUND: Hydrophobically associating water‐soluble polymers are of great interest because they possess unique rheological behaviour that results from the reversible association/dissociation process of their hydrophobic moieties. In this study, we focused on the structure of hydrophobic monomers related to the rheological and viscoelastic behaviours in semi‐dilute solutions of acrylamide polymers modified with small amounts of N‐alkyl‐ and N‐arylalkylacrylamides (0.5 and 1 mol%).

RESULTS: Associative efficiency increases with the length of the graft alkyl chain, with its proportion in the copolymer and with the presence of an aromatic group at the end of the alkyl graft chain. Introduction of hydrophobic groups induces a slowing down of the dynamics of the system, particularly marked for copolymers containing phenyldecyl chains.

CONCLUSION: At low frequencies, solutions behave as Newtonian liquids; at higher frequencies, solutions of strongly associative systems behave as a solid with a storage modulus higher than the loss modulus and little dependency on the frequency. The system is a transient network whose dynamics depend on entanglements and hydrophobic associations. The presence of the hydrophobic groups induces an increase of the final relaxation time, even more pronounced since these associations are strong. Copyright © 2008 Society of Chemical Industry
Poly(acrylonitrile‐co‐methyl methacrylate‐co‐methyl acrylate): Synthesis and stereosequence distribution analysis by 2D NMR
Authors: Brar Ajaib S. , Goyal Ashok K. , Hooda Sunita , Shankar Ravi
Published: November 2008

Terpolymers of acrylonitrile (A), methyl methacrylate (B), and methyl acrylate (M) were synthesized under optimized atom transfer radical polymerization conditions using 2‐bromopropionitrile as an initiator and CuBr/dinonyl bipyridine as a catalyst. Variation of the feed composition led to terpolymers with different compositions. Composition of synthesized terpolymers were calculated from quantitative 13C{1H} NMR spectra. Number average molecular weight and polydispersity index were determined by gel permeation chromatography. The overlapping and broad signals of the terpolymers were assigned completely to various compositional and configurational sequences by correlation of one‐dimensional 1H, 13C{1H}, and distortionless enhancement by polarization transfer and two‐dimensional heteronuclear single quantum coherence (HSQC) and total correlation spectroscopy (TOCSY). 2D HSQC NMR study shows one to one correlation between carbon and proton signals, while 2D TOCSY spectra were used to confirm 1, 2 bond geminal couplings between nonequivalent protons of same methylene group. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 25–37, 2009
Polyisobutylene‐based segmented polyureas. I. Synthesis of hydrolytically and oxidatively stable polyureas
Authors: Jewrajka Suresh K. , Yilgor Emel , Yilgor Iskender , Kennedy Joseph P.
Published: November 2008

Novel segmented polyurea elastomers containing soft polyisobutylene (PIB) segments were synthesized and characterized. The key ingredient, primary amine‐telechelic PIB oligomers (NH2‐PIB‐NH2) with number average molecular weights of 2500 and 6200 g/mol were synthesized. PIB‐based polyureas were prepared by using various aliphatic diisocyanates and diamine chain extenders with hard segment contents between 9.5 and 46.5% by weight. All copolymers displayed microphase morphologies as determined by dynamic mechanical analysis. Tensile strengths of nonchain‐extended and chain‐extended polyureas showed a linear dependence on the urea hard segment content. PIB‐based polyureas prepared with NH2‐PIB‐NH2 of Mn = 2500 g/mol, 4,4′‐methylendbis(cyclohexylisocyantate), and 1,6‐diaminohexane containing 45% hard segment exhibited 19.5 MPa tensile strength which rose to 23 MPa upon annealing at 150 °C for 12 h. With increasing hard segment content, elongation at break decreased from ∼ 450% to a plateau of 110%. The hydrolytic and oxidative stability of PIB‐based polyureas were unprecedented. Although commercial “oxidatively resistant” thermoplastic polyurethanes degraded severely upon exposure to boiling water or concentrated nitric acid, the experimental polyureas survived without much degradation in properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 38–48, 2009
Preparation of H‐shaped ABCAB terpolymers by atom transfer radical coupling
Authors: Luo Xiaolan , Wang Guowei , Huang Junlian
Published: November 2008

H‐shaped ABCAB terpolymers composed of polystyrene (PS) (A), poly(ethylene oxide) (PEO) (B), and poly(tert‐butyl acrylate) (PtBA) (C) were prepared by atom transfer radical coupling reaction using ABC star terpolymers as precursors, CuBr and N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) as catalysts, and nanosize copper as the reducing agent. The synthesis of 3‐miktoarm star terpolymer PS‐PEO‐(PtBA‐Br) involved following steps: (1) the preparation of PS with an active and an ethoxyethyl‐ptotected hydroxyl group at the same end; (2) the preparation of diblock copolymer PS‐b‐PEO with ethoxyethyl‐protected group at the junction point through the ring‐opening polymerization (ROP) of EO; (3) after de‐protection of ethoxyethyl group and further modification of hydroxyl group, tBA was polymerized by atom transfer radical polymerization using PS‐b‐PEO with 2‐bromoisobutyryl functional group as macroinitiator. The H‐shaped terpolymer could be successfully formed by atom transfer radical coupling reaction in the presence of small quantity of styrene, CuBr/PMDETA, and Cu at 90 °C. The copolymers were characterized by SEC, 1H NMR, and FTIR in detail. The optimized coupling temperature is 90 °C. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 59–68, 2009
Unimolecular micelles and reverse micelles based on hyperbranched polyethers—Comparative study of AB2 + A‐R and A2 + B3 + A‐R type strategies
Authors: Saha Animesh , Ramakrishnan S.
Published: November 2008

Core‐shell type hyperbranched polymers that are capable of forming unimolecular micelles and reverse micelles in aqueous and hydrocarbon medium, respectively, were synthesized via two approaches, namely AB2 + A‐R and A2 + B3 + A‐R type copolymerizations. In case of micelle‐forming polymers, an AB2 monomer carrying a decamethylene spacer was used along with heptaethylene glycol monomethyl ether (HPEG) as the A‐R type comonomer. One the other hand, for the preparation of reverse micelle‐forming polymers, an AB2 monomer containing an oligo(oxyethylene) spacer was used along with cetyl alcohol as the A‐R type comonomer. The former was readily soluble in water while the latter was soluble in hydrocarbon solvents like hexane. NMR spectral studies confirmed that both the approaches generated highly branched structures wherein about 65–70% of the terminal B groups were capped by the A‐R comonomer. Dye‐uptake measurements revealed that the polymers prepared via the AB2 + A‐R approach exhibited a significantly larger uptake compared with those prepared via the A2 + B3 + A‐R approach. This suggests that the AB2 + A‐R approach generates hyperbranched polymers with better defined core‐shell topology when compared with polymers prepared via the A2 + B3 + A‐R approach, which is in accordance with previous studies that suggest that A2 + B3 approach yields polymers with significantly lower branching levels and consequently less compact structures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 80–91, 2009