bluuebunny/crossref_metadata_2025 huggingface dataset:
A cell‐based Dkk1 binding assay reveals roles for extracellular domains of LRP5 in Dkk1 interaction and highlights differences between wild‐type and the high bone mass mutant LRP5(G171V)
Authors: Murrills Richard J. , Matteo Jeanne J. , Bhat Bheem M. , Coleburn Valerie E. , Allen Kristina M. , Chen Wei , Damagnez Veronique , Bhat Ramesh A. , Bex Frederick J. , Bodine Peter V.N.
Published: September 2009

Dkk1 is a secreted antagonist of the LRP5‐mediated Wnt signaling pathway that plays a pivotal role in bone biology. Because there are no well‐documented LRP5‐based assays of Dkk1 binding, we developed a cell‐based assay of Dkk1/LRP5 binding using radioactive 125I‐Dkk1. In contrast to LRP6, transfection of LRP5 alone into 293A cells resulted in a low level of specific binding that was unsuitable for routine assay. However, co‐transfection of LRP5 with the chaperone protein MesD (which itself does not bind Dkk1) or Kremen‐2 (a known Dkk1 receptor), or both, resulted in a marked enhancement of specific binding that was sufficient for evaluation of Dkk1 antagonists. LRP5 fragments comprising the third and fourth β‐propellers plus the ligand binding domain, or the first β‐propeller, each inhibited Dkk1 binding, with mean IC50s of 10 and 196 nM, respectively. The extracellular domain of Kremen‐2 (“soluble Kremen”) was a weaker antagonist (mean IC50 806 nM). We also found that cells transfected with a high bone mass mutation LRP5(G171V) had a subtly reduced level of Dkk1 binding, compared to wild type LRP5‐transfected cells, and no enhancement of binding by MesD. We conclude that (1) LRP5‐transfected cells do not offer a suitable cell‐based Dkk1 binding assay, unless co‐transfected with either MesD, Kremen‐2, or both; (2) soluble fragments of LRP5 containing either the third and fourth β‐propellers plus the ligand binding domain, or the first β‐propeller, antagonize Dkk1 binding; and (3) a high bone mass mutant LRP5(G171V), has subtly reduced Dkk1 binding, and, in contrast to LRP5, no enhancement of binding with MesD. J. Cell. Biochem. 108: 1066–1075, 2009. © 2009 Wiley‐Liss, Inc.
Polyamine effects on cell function: Possible central role of plasma membrane PI(4,5)P2
Authors: Coburn Ronald F.
Published: September 2009

The polyamines spermidine, spermine, and putrescine are intimately involved in and required for cell growth and proliferation. There are also multiple effects of polyamines on other cellular processes that seem not to be a result of changes in protein expression. It is a daunting task to classify and understand cellular effects of endogenous polyamines. There has been no central hypothesis how these effects can occur or how spermine and spermidine could be targeted to various signal transduction cascades. However, now there is evidence that multiple effects of endogenous polyamines on different cellular processes may involve plasma membrane PI(4,5)P2 and recent evidence of how polyamines could be targeted to specific cellular functions. J. Cell. Physiol. 221: 544–551, 2009. © 2009 Wiley‐Liss, Inc.
The mammalian anti‐proliferative BTG/Tob protein family
Authors: Winkler G. Sebastiaan
Published: September 2009

The mammalian BTG/Tob family comprises six proteins (BTG1, BTG2/PC3/Tis21, BTG3/ANA, BTG4/PC3B, Tob1/Tob and Tob2), which regulate cell cycle progression in a variety of cell types. They are characterised by the conserved N‐terminal domain spanning 104–106 amino acids. Recent biochemical and structural data indicate that the conserved BTG domain is a protein–protein interaction module, which is capable of binding to DNA‐binding transcription factors as well as the paralogues CNOT7 (human Caf1/Caf1a) and CNOT8 (human Pop2/Calif/Caf1b), two deadenylase subunits of the Ccr4‐Not complex. Consistent with this finding, several members of the BTG/Tob family are shown to be implicated in transcription in the nucleus and cytoplasmic mRNA deadenylation and turnover. The C‐terminal regions are less conserved and appear to mediate protein–protein interactions that are unique to each family member. The human and mouse BTG/Tob proteins will be the focus of this review and structural aspects of BTG/Tob interactions with components of the Ccr4‐Not complex, and the role of the BTG/Tob proteins in the regulation of gene expression, tumourigenesis and cancer will be discussed. J. Cell. Physiol. 222:66–72, 2010. © 2009 Wiley‐Liss, Inc.
Runx2, p53, and pRB status as diagnostic parameters for deregulation of osteoblast growth and differentiation in a new pre‐chemotherapeutic osteosarcoma cell line (OS1)
Authors: Pereira Barry P. , Zhou Yefang , Gupta Anurag , Leong David T. , Aung Khin Zarchi , Ling Ling , Pho Robert W.H. , Galindo Mario , Salto‐Tellez Manuel , Stein Gary S. , Cool Simon M. , van Wijnen Andre J. , Nathan Saminathan S.
Published: September 2009

Osteosarcomas are the most prevalent primary bone tumors found in pediatric patients. To understand their molecular etiology, cell culture models are used to define disease mechanisms under controlled conditions. Many osteosarcoma cell lines (e.g., SAOS‐2, U2OS, MG63) are derived from Caucasian patients. However, patients exhibit individual and ethnic differences in their responsiveness to irradiation and chemotherapy. This motivated the establishment of osteosarcoma cell lines (OS1, OS2, OS3) from three ethnically Chinese patients. OS1 cells, derived from a pre‐chemotherapeutic tumor in the femur of a 6‐year‐old female, were examined for molecular markers characteristic for osteoblasts, stem cells, and cell cycle control by immunohistochemistry, reverse transcriptase‐PCR, Western blotting and flow cytometry. OS1 have aberrant G‐banded karyotypes, possibly reflecting chromosomal abnormalities related to p53 deficiency. OS1 had ossification profiles similar to human fetal osteoblasts rather than SAOS‐2 which ossifies ab initio (P < 0.05). Absence of p53 correlates with increased Runx2 expression, while the slow proliferation of OS1 cells is perhaps attenuated by pRB retention. OS1 express mesenchymal stem cell markers (CD44, CD105) and differ in relative expression of CD29, CD63, and CD71 to SAOS‐2. (P < 0.05). Cell cycle synchronization with nocodazole did not affect Runx2 and CDK1 levels but decreased cyclin‐E and increased cyclin‐A (P < 0.05). Xenotransplantion of OS1 in SCID mice yields spontaneous tumors that were larger and grew faster than SAOS‐2 transplants. Hence, OS1 is a new osteosarcoma cell culture model derived from a pre‐chemotherapeutic ethnic Chinese patient, for mechanistic studies and development of therapeutic strategies to counteract metastasis and deregulation of mesenchymal development. J. Cell. Physiol. 221: 778–788, 2009. © 2009 Wiley‐Liss, Inc.
Activation of nuclear factor kappa B in mammary epithelium promotes milk loss during mammary development and infection
Authors: Connelly Linda , Barham Whitney , Pigg Rachel , Saint‐Jean Leshana , Sherrill Taylor , Cheng Dong‐Sheng , Chodosh Lewis A. , Blackwell Timothy S. , Yull Fiona E.
Published: September 2009

We investigated whether nuclear factor kappa B (NF‐κB), which exhibits a regulated pattern of activity during murine mammary gland development, plays an important role during lactation and involution, when milk production ceases and the gland undergoes apoptosis and re‐modeling. We generated a doxycycline inducible transgenic mouse model to activate NF‐κB specifically in the mammary epithelium through expression of a constitutively active form of IKK2, the upstream kinase in the classical NF‐κB signaling cascade. We found that activation of NF‐κB during involution resulted in a more rapid reduction in milk levels and increased cleavage of caspase‐3, an indicator of apoptosis. We also found that activation of NF‐κB during lactation with no additional involution signals had a similar effect. The observation that NF‐κB is a key regulator of milk production led us to investigate the role of NF‐κB during mastitis, an infection of the mammary gland in which milk loss is observed. Mammary gland injection of E. coli LPS resulted in activation of NF‐κB and milk loss during lactation. This milk loss was decreased by selective inhibition of NF‐κB in mammary epithelium. Together, our data reveal that activation of NF‐κB leads to milk clearance in the lactating mammary gland. Therefore, targeting of NF‐κB signaling may prove therapeutic during mastitis in humans and could be beneficial for the dairy industry, where such infections have a major economic impact. J. Cell. Physiol. 222:73–81, 2010. © 2009 Wiley‐Liss, Inc.
Induction of Th17 differentiation by corneal epithelial‐derived cytokines
Authors: Zheng Xiaofen , Bian Fang , Ma Ping , De Paiva Cintia S. , Stern Michael , Pflugfelder Stephen C. , Li De‐Quan
Published: September 2009

This study was to explore a potential role of epithelium‐derived cytokines in Th17 differentiation. Th17 induction was evaluated by murine CD4+T cells treated with different combinations of five inducing cytokines, or conditioned media of human corneal epithelial cells (HCECs) exposed to a variety of stimuli. Th17 differentiation was determined by measuring Th17 associated molecules, IL‐17A, IL‐17F, IL‐22, CCL‐20, and STAT3 at mRNA and protein levels, and numbers of IL‐17‐producing T cells by real‐time PCR, and cytokine immunobead and ELISPOT assays, respectively. IL‐23 was the strongest inducer for expanding Th17 cells in the presence of TGF‐β1 + IL‐6; and IL‐1β was the strongest Th17 amplifier in the presence of TGF‐β1 + IL‐6 + IL‐23. These inducing cytokines were found to be significantly stimulated in HCECs challenged by hyperosmotic media (450 mOsM), microbial components (polyI:C, flagellin, R837, and other TLR ligands) and TNF‐α. Interestingly, when incubated with conditioned media of HCECs irritated by polyI:C or TNF‐α, CD4+T cells displayed increased mRNA levels of IL‐17A, IL‐17F, IL‐22, CCL‐20, and STAT3, increased IL‐17 protein in the supernatant, and increased numbers of IL‐17‐producing T cells (Th17 cells). These findings demonstrate for the first time that Th17 differentiation can be promoted by cytokines produced by corneal epithelium that are exposed to hyperosmotic, microbial, and inflammatory stimuli. J. Cell. Physiol. 222:95–102, 2010. © 2009 Wiley‐Liss, Inc.
Variations of the origin of renal arteries in the fetus identified on power Doppler and 3D sonography
Authors: Degani Shimon , Leibovitz Zvi , Shapiro Israel , Ohel Gonen
Published: September 2009

Purpose.

To investigate anatomic variations of renal arteries (RAs) using 2‐dimensional (2D)/3D power Doppler sonography (PDUS) in normal fetuses and in fetuses with renal anomalies.

Methods.

The origin, direction, and distribution of RAs were studied in 120 fetuses without renal malformations using 2D/3D PDUS. Studies were performed between 14 and 17 weeks of gestation age on 64 male and 56 female fetuses. PDUS of the RAs was also performed in 12 fetuses with renal anomalies.

Results.

In 117/120 fetuses, a single RA was found to originate from each side of the abdominal aorta. The origin of the right RA from the abdominal aorta was superior to, at the same level as, and inferior to that of the left RA in 47% (55/117), 25.5% (30/117), and 27.5% (32/117) of the cases, respectively. An accessory right RA was found in 3 cases. Bifurcation of the right RA was found in 2 cases. There were no variations of the origin of renal vessels in 69% of the cases (83/120), whereas the remaining 31% (37/120) had 1 or several variation patterns. Variations in renal vessels were found in 8 of the 12 fetuses with renal malformations: accessory artery in 3 cases, origin of the right RA from the iliac artery in horseshoe kidney and in 2 cases with pelvic kidney, and bifurcation in 2 of the fetuses with double collecting system.

Conclusions.

Variations in origin and distribution of fetal RAs are frequently observed in normal pregnancies. The majority of renal malformations are associated with such vascular variations. © 2009 Wiley Periodicals, Inc. J Clin Ultrasound, 2010
Evaluation of the hepatic artery anastomosis by intraoperative sonography with high‐frequency transducer in right‐lobe graft living donor liver transplantation
Authors: Mun Han Song , Kim Kyoung Won , Song Gi‐Won , Ahn Chul‐Soo , Kim So Yeon , Hwang Shin , Lee Sung Gyu
Published: September 2009

Objective

To describe the usefulness of intraoperative ultrasonography (IOUS) with high‐frequency transducer in living donor liver transplantation (LDLT) using right‐lobe graft (RLG).

Method

This retrospective study was approved by our institutional review board. We performed IOUS in 22 patients (17 men and 5 women, aged 51 ± 9.0 years) during LDLT with RLG using a Sequoia 512 scanner with an 8–12‐MHz linear transducer. Hepatic artery (HA) anastomosis was identified on gray‐scale US, and the diameter and percentage of stenosis of the anastomosis were measured. The HA was evaluated to detect thrombus or dissection in the region of anastomosis. Doppler study of the graft HA was also performed. Patients were divided into those with and without abnormalities, including thrombosis, dissection, and abnormal Doppler parameters (peak systolic velocity < 30 cm/s or > 2 m/s, resistance index < 0.5, and systolic acceleration time > 80 msec).

Result

On gray‐scale and Doppler IOUS study, abnormalities were found in 10 of 22 patients. Diagnoses were anastomotic stenosis (n = 2), celiac stenosis (n = 1), compromise of HA inflow due to systemic hypotension (n = 1), HA thrombosis (n = 2), and HA dissection (n = 4). Re‐anastomoses were done in 3 case (2 stenoses and 1 thrombosis). Uneventful postoperative recovery occurred in the other 7 patients without re‐anastomosis.

Conclusion

IOUS with high‐frequency transducer is a useful method to make an early diagnosis of HA complications of LDLT with RLG. © 2009 Wiley Periodicals, Inc. J Clin Ultrasound, 2010
Trumpet maneuver in the sonographic diagnosis of an external laryngocele
Authors: Conkbayir Isik , Keyik Bahri , Hekimoglu Koray , Cifci Egemen , Yanik Bahar
Published: September 2009

Laryngocele is an uncommon disease defined as an abnormal dilatation or herniation of the laryngeal saccule, forming an air‐filled cavity. Radiologic evaluation of a suspected laryngocele generally includes plain radiographs, CT, and MRI. There are very few reports in the literature on sonographic findings of laryngocele. Trumpet maneuver has been reported in CT examination for the diagnosis of laryngocele. However, to the best of our knowledge, the use of trumpet maneuver in the sonographic diagnosis of laryngocele has not been previously described. This report presents the sonographic findings of an external laryngocele while performing the trumpet maneuver. © 2009 Wiley Periodicals, Inc. J Clin Ultrasound, 2010
Deep thiopental anesthesia alters steady‐state glucose homeostasis but not the neurochemical profile of rat cortex
Authors: Lei Hongxia , Duarte Joao M.N. , Mlynarik Vladimir , Python Agathe , Gruetter Rolf
Published: September 2009

Barbiturates are regularly used as an anesthetic for animal experimentation and clinical procedures and are frequently provided with solubilizing compounds, such as ethanol and propylene glycol, which have been reported to affect brain function and, in the case of 1H NMR experiments, originate undesired resonances in spectra affecting the quantification. As an alternative, thiopental can be administrated without any solubilizing agents. The aim of the study was to investigate the effect of deep thiopental anesthesia on the neurochemical profile consisting of 19 metabolites and on glucose transport kinetics in vivo in rat cortex compared with α‐chloralose using localized 1H NMR spectroscopy. Thiopental was devoid of effects on the neurochemical profile, except for the elevated glucose at a given plasma glucose level resulting from thiopental‐induced depression of glucose consumption at isoelectrical condition. Over the entire range of plasma glucose levels, steady‐state glucose concentrations were increased on average by 48% ± 8%, implying that an effect of deep thiopental anesthesia on the transport rate relative to cerebral glucose consumption ratio was increased by 47% ± 8% compared with light α‐chloralose‐anesthetized rats. We conclude that the thiopental‐induced isoelectrical condition in rat cortex significantly affected glucose contents by depressing brain metabolism, which remained substantial at isoelectricity. © 2009 Wiley‐Liss, Inc.
KATP channel openers protect mesencephalic neurons against MPP+‐induced cytotoxicity via inhibition of ROS production
Authors: Xie Juan , Duan Lei , Qian Xia , Huang Xu , Ding Jianhua , Hu Gang
Published: September 2009

Opening of ATP‐sensitive potassium (KATP) channels has been demonstrated to exert significant neuroprotection in in vivo and in vitro models of Parkinson's disease (PD), but the exact mechanism remains unclear. In the present study, various KATP channel openers (KCOs) sensitive to diverse KATP subunits were used to clarify the protective role of KATP channel opening in 1‐methyl‐4‐phenylpyridinium (MPP+)‐induced oxidative stress injury in mouse primary cultured mesencephalic neurons. The results showed that pretreatment with nonselective KCO pinacidil (Pin) or diazoxide (Dia), a KCO sensitive to Kir6.2/SUR1 KATP channels, protected mesencephalic neurons, especially dopaminergic neurons, against MPP+‐induced injury in a concentration‐dependent manner. However, cromakalim (Cro), an opener of Kir6.1/SUR2 but not Kir6.2/SUR1 KATP channels, failed to protect against MPP+‐induced cytotoxicity. Furthermore, Pin and Dia but not Cro significantly suppressed the elevation of reactive oxygen species (ROS) triggered by MPP+ and prevented the loss of mitochondrial member potential (ΔΨm) and the release of mitochondrial cyotchrome c. Consequently, opening of KATP channels expressed in neurons could protect primary mesencephalic neurons against MPP+‐induced cytotoxicity via inhibiting ROS overproduction and subsequently ameliorating mitochondrial function. © 2009 Wiley‐Liss, Inc.
Dispersive liquid–liquid microextraction using extraction solvent lighter than water
Authors: Farajzadeh Mir Ali , Seyedi Seyed Esmaeil , Shalamzari Mohammad Safi , Bamorowat Mehdi
Published: September 2009

For the first time a dispersive liquid–liquid microextraction method on the basis of an extraction solvent lighter than water was presented in this study. Three organophosphorus pesticides (OPPs) were selected as model compounds and the proposed method was carried out for their preconcentration from water samples. In this extraction method, a mixture of cyclohexane (extraction solvent) and acetone (disperser) is rapidly injected into the aqueous sample in a special vessel (see experimental section) by syringe. Thereby, a cloudy solution is formed. In this step, the OPPs are extracted into the fine droplets of cyclohexane dispersed into aqueous phase. After centrifuging the fine droplets of cyclohexane are collected on the upper of the extraction vessel. The upper phase (0.40 μL) is injected into the gas chromatograph (GC) for separation. Analytes were detected by a flame ionization detector (FID) (for high concentrations) or MS (for low concentrations). Some important parameters, such as the kind of extraction and dispersive solvents and volume of them, extraction time, temperature, and salt amount were investigated. Under the optimum conditions, the enrichment factors (EFs) ranged from 100 to 150 and extraction recoveries varied between 68 and 105%, both of which are relatively high over those of published methods. The linear ranges were wide (10–100 000 μg/L for GC‐FID and 0.01–1 μg/L for GC‐MS) and LODs were low (3–4 μg/L for GC‐FID and 0.003 μg/L for GC‐MS). The RSDs for 100.0 μg/L of each OPP in water were in the range of 5.3–7.8% (n = 5).
HPLC with polysaccharide chiral stationary phase in polar‐organic phase mode: Application to the asymmetric epoxidation of allylic alcohols
Authors: Morante‐Zarcero Sonia , del Hierro Isabel , Fajardo Mariano , Sierra Isabel
Published: September 2009

A simple and rapid HPLC method using a polysaccharide‐based chiral stationary phase (Chiralpak AD‐H) in polar‐organic phase mode has been developed for direct resolution of glycidyl nitrobenzoate (GNB) and 2‐methyl glycidyl nitrobenzoate (MGNB) enantiomers. ACN and methanol were used as mobile phase and the effects of the addition of ethanol and 2‐propanol as organic modifier in the mobile phase, flow rate and the column temperature were tested. The optimized conditions were: methanol/ethanol (80:20) at a flow rate of 0.9 mL/min and 40°C. Analysis time was ⪇13 min and the chiral resolution was ⪈2. The method was validated and resulted to be selective, precise and accurate. The method was found to be linear in 2–300 μg/mL range (R2 >0.999) with an LOD nearly 0.5 μg/mL for four enantiomers. GNB and MGNB enantiomers were obtained by asymmetric epoxidation of allyl alcohol and 2‐methyl allyl alcohol, respectively, using chiral titanium–tartrate complexes as catalyst and dichloromethane as solvent after in situ derivatization of the intermediate glycidols derivatives. The quite simple and rapid validated method was applied successfully for direct determination of the enantiomeric excess (⪈90%) and yield obtained in real samples of asymmetric epoxidation of allylic alcohols without further purification, workup or solvent removal. The method provides a useful and value‐added tool for controlling the enantiomeric purity of the synthesized epoxides.
Uncertainty in the determination of glucose in aqueous solutions by high‐performance liquid chromatography with evaporative light scattering detection
Authors: Nogueiro Estevinho Berta , Ferraz Amélia , Rocha Fernando , Santos Lúcia , Alves Arminda
Published: September 2009

The determination of glucose and other carbohydrates is the most widespread chemical analysis that is performed within the industries of food, beverage, forage, biomass, pulp and paper, pharmaceuticals among others. Besides that, sugar refineries need to control their products, by‐products and effluents, and furthermore, glucose in the sucrose refining process, is considered an impurity, which shall be controlled. Being HPLC the most currently instrumental technique used for glucose analysis, the evaporative light scattering detector (ELSD) offers advantages (sensitivity, possibility for operating in gradient mode) over the also used refractive index detector. In this work, an HPLC‐ELSD methodology was optimised and validated, aiming the estimate of the uncertainty associated with the results at low levels of concentration of glucose to be measured. Linearity of the response was obtained in the range of glucose concentrations from 20 to 300 mg/L, with an analysis time of 10 min. The global uncertainty was estimated accordingly to the bottom‐up approach used by Eurachem. It was 13% on average for concentrations from 100 to 300 mg/L. For lower concentrations, uncertainty increased significantly up to 30% in the vicinity of the LOD of the method.
Lysozyme in wine: A risk evaluation for consumers allergic to hen's egg
Authors: Weber Patrick , Kratzin Hartmut , Brockow Knut , Ring Johannes , Steinhart Hans , Paschke Angelika
Published: September 2009

Lysozyme used in wine production could present a risk for consumers allergic to hen's egg. Thus, precautionary labeling of lysozyme on wines has been adopted within the European Community by updating Annex IIIa by Directive 2007/68/EC on November 27, 2007. Since no scientific data is known about the actual amounts and risks of lysozyme in wines, various in vitro efforts and skin prick tests were applied in this study to evaluate the presence of lysozyme in wines and the reactivity of those residues in allergic individuals and to fulfill the claim of updating Annex IIIa announced in Directive 2003/89/EC. Depending on the wine's color (red or white wine) and fining with bentonite, which is known as an important step to remove unstable proteins mainly from white wines, diverse results were obtained concerning the amounts of lysozyme in finished wines and their in vitro and in vivo reactivity in humans allergic to hen's egg.
Conversion of 3‐aminopropionamide and 3‐alkylaminopropionamides into acrylamide in model systems
Authors: Zamora Rosario , Delgado Rosa M. , Hidalgo Francisco J.
Published: September 2009

Carbonyl compounds have been shown to play a major role in the conversion of asparagine into acrylamide. However, it is unclear at this point if its role is only restricted to the decarboxylation of the amino acid or if carbonyl compounds also play a role in the deamination reaction of the decarboxylated intermediates 3‐aminopropionamide and 3‐(alkylamino)propionamides. This study describes the deamination reaction of 3‐aminopropionamide and 3‐(alkylamino)propionamides (benzyl, phenylethyl, butyl, and octyl) in model systems and in the presence, or not, of different carbonyl compounds (alkadienals, alkenals, and alkanals). All these reactions were mainly produced at almost neutral or basic pH values. In addition, the reaction yields and the activation energies not only depended on the type of aminopropionamide involved but also on the water activity (aw) and in the presence, or not, of carbonyl compounds. However, there was not a clear correlation among the activation energies calculated for the different deamination reactions and the yields of acrylamide obtained; therefore, suggesting the existence of diverse pathways by which 3‐aminopropionamide and 3‐(alkylamino)propionamides are converted into acrylamide. In addition, these reactions are also competing with other carbonyl–amine reactions when carbonyl compounds are present. All these results suggest that the type of the intermediate aminopropionamide involved is going to play a major role in both the amount of acrylamide produced and the conditions required for its formation. On the other hand, the role of carbonyl compounds in the acrylamide produced, but not in the activation energy of the reactions implicated, seems to be more limited than either the type of amine or the aw. A detailed analysis of the type of the intermediate aminopropionamide formed in foods may help to define strategies for mitigating the formation of this food toxicant.
PAX5 activates the transcription of the human telomerase reverse transcriptase gene in B cells
Authors: Bougel Stéphanie , Renaud Stéphanie , Braunschweig Richard , Loukinov Dmitri , Morse III Herbert C , Bosman Fred T. , Lobanenkov Victor , Benhattar Jean
Published: September 2009

Telomerase is an RNA‐dependent DNA polymerase that synthesizes telomeric DNA. Its activity is not detectable in most somatic cells but it is reactivated during tumorigenesis. In most cancers, the combination of hTERT hypermethylation and hypomethylation of a short promoter region is permissive for low‐level hTERT transcription. Activated and malignant lymphocytes express high telomerase activity, through a mechanism that seems methylation‐independent. The aim of this study was to determine which mechanism is involved in the enhanced expression of hTERT in lymphoid cells. Our data confirm that in B cells, some T cell lymphomas and non‐neoplastic lymph nodes, the hTERT promoter is unmethylated. Binding sites for the B cell‐specific transcription factor PAX5 were identified downstream of the ATG translational start site through EMSA and ChIP experiments. ChIP assays indicated that the transcriptional activation of hTERT by PAX5 does not involve repression of CTCF binding. In a B cell lymphoma cell line, siRNA‐induced knockdown of PAX5 expression repressed hTERT transcription. Moreover, ectopic expression of PAX5 in a telomerase‐negative normal fibroblast cell line was found to be sufficient to activate hTERT expression. These data show that activation of hTERT in telomerase‐positive B cells is due to a methylation‐independent mechanism in which PAX5 plays an important role. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Pediatric rhabdomyosarcoma in Morocco
Authors: Hessissen Laila , Kanouni Lamya , Kili Amina , Nachef Mohamed Nacer , El Khorassani Mohamed , Benjaafar Noureddine , Khattab Mohamed , El Gueddari Brahim El Khalil
Published: September 2009

Background

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in the first two decades of life. There is, however, a paucity of reports on the pattern of its occurrence in Africa. This study analyses the epidemiological pattern, clinical features, histology, and outcome in Moroccan children presenting with RMS.

Methods

We retrospectively studied 100 consecutive cases of histologically proven RMS in previously untreated children <15 years old followed at the Pediatric Oncology Unit of the Children's Hospital of Rabat from January 1995 to December 2004.

Results

RMS represented 5% of all the patients treated for cancer during this period. The male/female ratio was 2:1 with a mean age at diagnosis of 5 years. The embryonal subtype was the most frequent (73%) and the head and neck was the most common site of disease, followed by the genito‐urinary tract and limbs. Chemotherapy was used in all patients; 44% also had a radical surgery and 23% radiation therapy. The event‐free survival (EFS) at 10 years was 39% with relapse as the first cause of treatment failure. The overall survival at 10 years was 70%. The rate of treatment abandonment was 37%.

Conclusion

Epidemiology and clinical features of RMS in Moroccan children does not differ from others countries. However, EFS is lower than that reported elsewhere due to occasional lack of availability of drugs, inadequate local control, and abandonment. Pediatr Blood Cancer 2010; 54:25–28. © 2009 Wiley‐Liss, Inc.
Design, synthesis and polymerization of highly branched pseudodendrimers through tandem reactions
Authors: Wang Junyan , Johnson Dave M
Published: September 2009

BACKGROUND: Pseudodendrimers are hyperbranched polymers which are isomeric with dendrimers, that is, each repeat unit is either fully reacted or only singly reacted. The careful design of an ABB′ monomer leads to higher branching by virtue of tandem reactions that increase the reactivity of linear units during polymerization, leading to fully reacted repeat units. The resulting polymers are predicted to be very highly branched, and in the optimum case, pseudodendrimers.

RESULTS: Our work shows that 6‐amino‐3‐bromophthalide leads to a highly branched polymer via bromohydrin decomposition during polymerization, giving polymers of M̄ = of 3000 and a polydispersity index of 1.03. Our findings indicate a degree of branching of 0.84. The synthesis of similar polymers using different techniques confirms our proposed intermediate.

CONCLUSION: We have demonstrated a new class of hyperbranched polymers which are highly branched, and may be considered pseudodendrimers. Copyright © 2009 Society of Chemical Industry
Cationic polymerization of styrene involving ionization of the CCl bond in ionic liquid/SO2 mixture
Authors: Baśko Małgorzata , Biedroń Tadeusz , Kubisa Przemysław
Published: September 2009

There has been a recent upsurge in interest in use of ionic liquids as reaction media for various chemical processes. Until recently, ionic liquids were considered as highly polar solvents. Our earlier investigation indicated that cationic polymerization of styrene initiated by aryl (alkyl) chlorides in ionic liquids may proceed even in the absence of coinitiator (Lewis acid). Polymerization, however, did not conform to controlled polymerization scheme. More recently, it has been claimed that ionic liquids are not as polar as it was previously assumed. Independently, high solubility of sulfur dioxide in ionic liquids was noticed. As sulfur dioxide displays a high ionizing power toward organic halides, we applied ionic liquid/sulfur dioxide mixture as a solvent in cationic polymerization of styrene initiated by aryl (alkyl) chlorides. Results show that in this reaction medium ionization of the CCl bond is facilitated, and the contribution of chain transfer reaction can be reduced as compared with polymerization in ionic liquid alone. Ionization of the CCl bond, however, is still not sufficiently fast to ensure conditions of controlled polymerization. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5251–5257, 2009
Polyisobutylene‐based polyurethanes. III. Polyurethanes containing PIB/PTMO soft co‐segments
Authors: Erdodi Gabor , Kang Jungmee , Kennedy Joseph P. , Yilgor Emel , Yilgor Iskender
Published: September 2009

The synthesis, characterization, and structure–property behavior of polyurethanes containing polyisobutylene (PIB)/poly(tetramethylene oxide) (PTMO) soft co‐segments and bis(4‐isocyanatocyclohexyl)methane (HMDI)/hexanediol (HDO) hard segments is presented. The mechanical (stress/strain, hardness, and hysteresis) properties of these novel polyurethanes were investigated over a broad composition range. PIB‐based polyurethanes with HMDI/HDO hard segments showed better mechanical properties than earlier polyurethanes containing highly crystalline hard segments. The addition of moderate amounts (20% by weight) of PTMO significantly increased both tensile strengths and elongation. In the presence of larger amounts of PIB, these polyurethanes are expected to possess oxidative/hydrolytic/enzymatic stabilities superior to commercially available polyurethanes. These polyurethanes are softer and exhibit hysteresis superior to or comparable with conventional polyurethanes. According to initial thermal studies, these materials show good melt processibility. Overall, the mechanical properties of PIB based hybrid polyurethanes are similar to commercially important polyurethane type biomaterials. Our results show that the incorporation of PTMO segments to PIB‐based polyurethanes significantly improves elastomeric properties. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5278–5290, 2009
Synthesis and white electroluminescent properties of multicomponent copolymers containing polyfluorene, oligo(phenylenevinylene), and porphyrin derivatives
Authors: Li Hui , Xiang Na , Wang Lei , Zhao Bin , Shen Ping , Lu Junjian , Tan Songting
Published: September 2009

Two novel multicomponent copolymers (P1 and P2) containing polyfluorene (PF), oligo(phenylenevinylene) (OPV), and porphyrin (Por) derivatives were synthesized according to the Suzuki polymerization method. The structures, optical, and electrochemical properties of the two model compounds (OPV and Por) and multicomponent copolymers were characterized by 1H NMR, FTIR, elemental analysis, UV–vis spectroscopy, photoluminescence, and cyclic voltammetry, respectively. Both of the copolymers exhibit thermotropic liquid crystalline properties and represent the characteristic Schlieren textures in a wide temperature range. Electroluminescence spectra of these copolymers exhibit broadband emissions covering the entire visible region from 400 to 700 nm. The single layer polymer light emitting diodes device based on P2 with a configuration of indium tin oxide/poly(ethylenedioxythiophene):poly(styrenesulfonic acid)/polymers/Ca/Al emits white light with the Commission Internationale de l′Eclairage chromaticity coordinates of (0.29, 0.30), maximum brightness of 443 cd/m2. The white‐light‐emitting devices based on the novel multicomponent copolymers exhibit low turn‐on voltage, and good color stability at different driving voltages as well. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5291–5303, 2009
High performance polymer field‐effect transistors based on polythiophene derivative with conjugated side chain
Authors: He Youjun , Wu Weiping , Liu Yunqi , Li Yongfang
Published: September 2009

Poly(3‐[2‐(5‐hexyl‐2‐thienyl) ethenyl]‐2,2′‐bithiophene) (P2, see Scheme 1) with conjugated thienylvinyl side chain was synthesized by copolymerization of the thiophene units with and without conjugated side chain with Pd‐catalyzed Stille coupling method. For comparison, P1 with the hexyl side chain instead of conjugated side chain was also synthesized. P2 film shows broad absorption in the visible region with absorption edge at about 700 nm. The solution‐processed polymer field‐effect transistors were fabricated and characterized with bottom gate/top contact geometry. The organic field‐effect transistors (OFET) based on P2 showed an average hole mobility of about 0.034 cm2/Vs (the highest value reached 0.061 cm2/Vs) upon annealing at about 180 °C for 30 min, with a threshold voltage of −1.15 V and an on/off ratio of 104 with n‐octadecyltrichlorosilane (OTS) modified SiO2 substrate. In comparison, the OFET based on P1 displayed a hole mobility of 8.9 × 10–4 cm2/Vs and an on/off ratio of 104 with OTS modified SiO2 substrate. The results indicate that the polythiophene derivative with conjugated thienylvinyl side chain is a promising polymer for the application in polymer field‐effect transistors. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5304–5312, 2009
Poly(cyclohexene oxide)/clay nanocomposites by photoinitiated cationic polymerization via activated monomer mechanism
Authors: Oral Ayhan , Tasdelen Mehmet Atilla , Demirel Adem Levent , Yagci Yusuf
Published: September 2009

Poly(cyclohexene oxide) (PCHO)/clay nanocomposites were prepared by in situ photoinitiated activated monomer cationic polymerization. The polymerization of cyclohexene oxide through the interlayer galleries of the clay can provide distribution of the clay layers in the polymer matrix homogenously and results in the formation of PCHO/clay nanocomposites. The exfoliated structures were characterized by X‐ray diffraction spectroscopy, thermogravimetric analysis, transmission electron microscopy, and atomic force microscopy. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5328–5335, 2009
Synthesis and characterization of new low bandgap polyfluorene copolymers for bulk heterojunction solar cells
Authors: Hsu Steve Lien‐Chung , Lin Yu‐Chen , Lee Rong‐Fong , Sivakumar Chinnaiah , Chen Jen‐Sue , Chou Wei‐Yang
Published: September 2009

Two new low bandgap alternating polyfluorene copolymers based on dioctylfluorene and donor‐acceptor‐donor monomers have been synthesized via a Suzuki polymerization reaction. The resulting copolymers have low optical bandgaps at 1.99–1.98 eV. The bulk heterojunction polymer solar cells were fabricated with the conjugated polymers as the electron donor and 6.6‐phenyl C61‐butyric acid methyl ester as the electron acceptor. The power conversion efficiencies of the solar cells based on copolymers 1 and 2 are 0.37 and 0.42%, respectively, under the illumination of AM 1.5, 100 mW/cm2. The results indicate that the two copolymers are promising conjugated polymers for polymer solar cells. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5336–5343, 2009
An efficient approach to synthesize polysaccharides‐graft‐poly(p‐dioxanone) copolymers as potential drug carriers
Authors: Lu Fang , Wang Xiu‐Li , Chen Si‐Chong , Yang Ke‐Ke , Wang Yu‐Zhong
Published: September 2009

Starch and poly(p‐dioxanone) (PPDO) are the natural and synthetic biodegradable and biocompatible polymers, respectively. Their copolymers can find extensive applications in biomedical materials. However, it is very difficult to synthesize starch‐graft‐PPDO copolymers in common organic solvents with very good solubility. In this article, well‐defined polysaccharides‐graft‐poly(p‐dioxanone) (SAn‐PPDO) copolymers were successfully synthesized via the ring‐opening polymerization of p‐dioxanone (PDO) with an acetylated starch (SA) initiator and a Sn(Oct)2 catalyst in bulk. The copolymers were characterized via Fourier transform infrared spectroscopy, 1H NMR, gel permeation chromatography, thermogravimetric analysis (TG), differential scanning calorimetry, and wide angle x‐ray diffraction. The in vitro degradation results showed that the introduction of SA segments into the backbone chains of the copolymers led to an enhancement of the degradation rate, and the degradation rate of SAn‐PPDO increased with the increase of SA wt %. Microspheres with an average volume diameter of 20 μm, which will have potential applications in controlled release of drugs, were successfully prepared by using these new copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5344–5353, 2009
Incorporation of poly(2‐acrylamido‐2‐methyl‐N‐propanesulfonic acid) segments into block and brush copolymers by ATRP
Authors: McCullough Lynne A. , Dufour Bruno , Matyjaszewski Krzysztof
Published: September 2009

2‐Acrylamido‐2‐methyl‐N‐propanesulfonic acid (AMPSA) was successfully polymerized via atom transfer radical polymerization (ATRP) using a copper chloride/2,2′‐bipyridine (bpy) catalyst complex afterin situneutralization of the acidic proton in AMPSA with tri(n‐butyl)amine (TBA). A 5 mol % excess of TBA was required to completely neutralize the acid and prevent protonation of the bpy ligand, as well as to avoid side reactions caused by large excess of TBA. The use of activators generated by electron transfer (AGET) ATRP with ascorbic acid as reducing agent resulted in both increased conversion of the AMPSA monomer during polymerization (up to 50% with a 0.8 [ascorbic acid]/[Cu(II)] ratio) and much shorter polymerization times (<30 min). Block copolymers and molecular brushes containing AMPSA side chains were prepared using this method, and the solution and surface behavior of these materials were investigated. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5386–5396, 2009
Photoluminescence behaviors of organic soluble DNA bearing carbazole and pyrene derivatives as side‐chain substituents and effect of the copolymer structure on the Förster energy transfer process
Authors: Lee U Ra , Lee Jung Eun , Cho Min Ju , Kim Kyung Hwan , Kwon Young Wan , Jin Jung‐Il , Choi Dong Hoon
Published: September 2009

Organic soluble DNA bearing two different fluorophores in the side chain was prepared by reacting purified DNA with the cationic molecules 9‐(12‐bromododecyl)‐9H‐carbazole and (E)‐1‐(4‐(12‐bromododecyloxy)styryl)pyrene in water. Two homopolymers (CzDNA and PyDNA) and random copolymers (CzDNA‐co‐PyDNA) were prepared successfully. The absorption and photoluminescence (PL) behavior of CzDNA‐co‐PyDNA with pyrene derivative concentrations was investigated. As reference, we employed a guest‐host system and polymer blends using DNA homopolymers. The Förster energy transfer process was investigated in three different DNA systems. The DNA copolymer system showed much better energy transfer efficiency than the other DNA systems. The copolymers were mixed with 2‐{2‐[2‐(4‐diethylamino‐phenyl)‐vinyl]‐6‐methyl‐pyran‐4‐ylidene}‐malononitrile (DCM) at an optimum concentration. At low DCM concentration (0.3 wt %), undesired emissions were observed due to an incomplete energy transfer process from excited pyrene moieties. At high DCM concentration (5.0 wt %), red emissions were predominant; this is attributed to an efficient Förster energy transfer process. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5416–5425, 2009
Ionomers for proton exchange membrane fuel cells by sulfonation of novel dendritic multiblock copoly(ether‐sulfone)s
Authors: Matsumura Sumiko , Hlil Antisar R. , Al‐Souz Mohammed A. K. , Gaudet Julie , Guay Daniel , Hay Allan S.
Published: September 2009

The synthesis and properties of the first examples of dendritic multiblock coPESs, bearing sulfonated dendritic clusters, that form strong membranes are described. End‐capped dendritic multiblock coPESs with various average block lengths (n = 50–80) were synthesized by two‐step reactions. The synthesis of dendritic blocks consisting of difunctional dendritic block and monofunctional dendritic end‐group was accomplished by an aromatic nucleophilic substitution reaction of hexakis(4‐(4‐fluorophenylsulfonyl)phenyl)benzene with varying amounts of 1‐(4‐hydroxyphenyl)‐2,3,4,5,6‐pentaphenylbenzene, which provides a number of pendant phenyl rings as postsulfonation sites. Polycondensation of a controlled molar ratio between 4,4′‐dihydroxybenzophenone and bis(4‐fluorophenyl)sulfone monomers was carried out in the presence of the difunctional and monofunctional dendritic blocks in sulfolane at 215 °C for 3.5 h. Essentially six sulfonic acid groups were introduced into each hexaphenylbenzene moiety on the dendritic blocks by reaction with a large excess of chlorosulfonic acid, followed by hydrolysis with KOH aqueous solution. The introduction of longer average blocks (n = 60–80) into the dendritic PESs improved the mechanical properties of the resulting sulfonated dendritic PES membranes. At a level of IEC (0.92–1.26 meq/g) similar to Nafion (0.91 meq/g), PES membranes showed proton conductivities (58–67 mS/cm) comparable with that of Nafion (99 mS/cm). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5461–5473, 2009
Cylindrical molecular brushes with a loose grafting density
Authors: Deng Guohua , Chen Yongming
Published: September 2009

A cylindrical molecular brush with a low graft density was synthesized by two steps. Firstly, free radical alternating copolymerization of styrene (St) and N‐[2‐(2‐bromoisobutyryloxy)ethyl] maleimide (BiBEMI) gave a macroinitiator where pendant initiating sites for atom transfer radical polymerization (ATRP) being positioned along the backbone with an interval of four CC bonds. The backbone‐to‐be with an alternating sequence was verified by elemental analysis (EA). Secondly, grafting poly(tert‐butyl acrylate) chains from the macroinitiator by ATRP produced the novel molecular brush. Size exclusion chromatography, static light scattering (SLS), and 1H NMR and atomic force microscopy (AFM) were used to characterize the macroinitiator and the molecular brush. The results show that the backbone contains an average 730 repeat units (1 repeat unit = a pair of St and BiBEMI) and the absolute molecular weight of the brush, Mw,SLS, was 4.88 × 106 Da. The brush reveals a number average length Ln to be 96 nm under AFM observation on carbon coated mica, corresponding to the length per main chain monomer unit (Lunit) of 0.066 nm, indicating a less extended conformation due to the low grafting density. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5527–5533, 2009
Rheological behavior of biocomposites of silk fibroin fiber and poly(ε‐caprolactone): Effect of fiber network
Authors: Qiao Xiuying , Li Wei , Watanabe Hiroshi , Sun Kang , Chen Xiaodong
Published: September 2009

Rheological behavior was examined for biocomposites of rod‐like silk fibroin (SF) fiber and poly(ε‐caprolactone) (PCL) to investigate an effect(s) of the SF fiber network therein on the mechanical properties. At 160 °C where PCL was a homogeneous melt, linear viscoelastic tests revealed that the SF/PCL composites hardly relax to behave essentially as elastic solids (more precisely, plastic solids before yielding) at low frequencies. The corresponding equilibrium modulus G0 increased strongly with the SF volume fraction ϕSF (G0 ∼ ϕ) and was attributable to the elastic bending of the SF fibers incorporated in the network. The Doi‐Kuzuu model for non‐Brownian rods was modified for the SF/PCL composites by incorporating the rod–rod contact at equilibrium. The G0 calculated from this model was satisfactorily close to the data, in both ϕSF dependence and magnitude, lending support to the assignment of the composite elasticity to the fiber bending. The storage modulus G′ measured under large‐amplitude oscillatory shear (LAOS) was smaller than the linear viscoelastic G′, and this difference between the linear and nonlinear moduli was enhanced for the composites with a larger SF content and at lower frequencies. This nonlinear effect was attributable to a decrease of the effective fiber–fiber contacts sustaining the elasticity under LAOS. Under steady shear, the SF/PCL composites exhibited nonlinear (plastic) flow behavior associated with the stress overshoot, and their apparent viscosity was comparable to/lower than the viscosity of neat PCL matrix. The overshoot became much less significant on application of a second shear immediately after the first shear, while the overshoot was partly recovered after a quiescent rest between the first and second shears. These nonlinear features were attributable to slippage between shear‐oriented fibers and PCL matrix. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1957–1970, 2009