bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selectivity of Stabilized Benzhydrylium Ions
Authors: Denegri Bernard , Matić Mirela , Kronja Olga 
Published: February 2010

AbstractMethyl carbonates (1–4–OCO2Me) and phenyl carbonates (2–4–OCO2Ph) were subjected to solvolysis in the series of aqueous ethanol, the product ratios were determined and the selectivities (kE/kW) of the corresponding stabilized benzhydrylium ions 1–4 were calculated. The individual rate constants for ethanolysis (kE) and hydrolysis (kW) have been calculated. Ethanolysis proceeds via earlier more carbocation‐like transition state than hydrolysis. Due to more important solvation, kE decreases slower than kW if the fraction of the water in the binary solvent increases, which net effect is pronounced dependence of the selectivity on the solvent polarity. The selectivities of less stable carbocations 5–8 are reduced and influenced by the leaving group because of pairing and bending of the log k vs. E plot.
An Ultrasensitive Analytical Method Based on Chemiluminescence Sensing Electrochemical Parallel Catalytic Reaction Event
Authors: Guo Zhihui , Guo Ying , Zheng Xingwang 
Published: February 2010

AbstractAn ultrasensitive electrochemiluminescence (ECL) method on the combination of electrochemical parallel catalytic reaction and chemiluminesence signal sensing was proposed for improving ECL analytical characteristics using vanadate(V) as a representative. Vanadate(V) could be electrochemically reduced to generate vanadate(II) which could be chemically oxidized by potassium periodate to regenerate vanadate(V) and give parallel catalytic wave effect. Then, the reduced product of potassium periodate could react with butyl‐rhodamine B to emit a sensitive chemiluminescence signal. The chemiluminescence intensity was correlative with vanadate(V) concentration. The investigation on the electrochemical reaction rate constant (k0) confirmed that the speed of electrochemical reaction was faster than that of the subsequent chemiluminescence reaction. The possibility of the combination of electrochemical parallel catalytic reaction with chemiluminescence signal sensing was proved. The similar ECL behaviors could be observed at zirconia nanowires‐Nafion modified electrode. Because of the separation and enrichment effect of the modified electrode on vanadate(V), the selectivity and sensitivity was further improved greatly. Based on these findings, a new concept on the combination of electrochemical parallel catalytic reaction and chemiluminesence signal sensing was proposed and an ultrasensitive ECL method for the determination of vanadate(V) was developed at zirconia nanowires‐Nafion modified electrode. Under the optimum experimental conditions, the ECL intensity was linear with the concentration of vanadate(V) in the range of 2.0×10−12 mol/L–2.0×10−10 mol/L. The detection limit was 8.0×10−13 mol/L, which was more than 6 orders of magnitude lower than that observed by electrochemical current transduction for electrochemical parallel catalytic reaction at zirconia nanowires‐Nafion modified electrode.
Simultaneous Voltammetric Determination of Zn, Cd and Pb at Bismuth Nanopowder Electrodes with Various Particle Size Distributions
Authors: Lee Gyoung‐Ja , Kim Chang Kyu , Lee Min Ku , Rhee Chang Kyu 
Published: February 2010

AbstractEffect of particle size distribution on sensor characteristics of nano‐Bi fixed electrode has been investigated using square wave anodic stripping voltammetry. Bi nanopowders with various particle size distributions were synthesized by gas condensation (GC) method with the change of chamber pressure. As the chamber pressure decreased, the size of Bi nanopowder became smaller with narrower distribution due to a shorter residence time of Bi vapor. The square wave anodic stripping voltammograms (SWASV) showed well‐defined and highly reproducible peaks at −1.2 V, −0.8 V and −0.6 V (vs. SCE), which are closely related to the oxidation of Zn, Cd and Pb, respectively. The sensitivity and detection limit of the nano‐Bi fixed electrode were quantitatively estimated from the analyses of SWASV. From the results, it is concluded that as the size of Bi nanopowder becomes smaller with narrower particle size distribution, the sensitivity and detection limit of sensor electrode for Zn, Cd and Pb are improved, which is ascribed to the increase in electrochemical‐active surface area.
Green Synthesis of Silver Nanoparticles Using Ionic Liquid and Application for the Detection of Dissolved Oxygen
Authors: Tsai Tsung‐Hsuan , Thiagarajan Soundappan , Chen Shen‐Ming 
Published: February 2010

AbstractThe electrochemical synthesis of silver nanoparticles (nano‐Ag) has been successfully carried out on glassy carbon electrode (GCE) and indium tin oxide electrode (ITO) using 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMT) as green electrolytes. Further the electrodeposited nano‐Ag modified ITO electrode has been examined using atomic force microscopy (AFM), and X‐ray diffraction studies (XRD). The electrodeposited Ag nanoparticles on ITO were found in the size range of 5 to 35 nm. The nano‐Ag film modified GCE was further coated with nafion (Nf) and BMT (1 : 1 ratio) mixture and found to be stable in BMT and in pH 7 phosphate buffer solution (PBS). The nano‐Ag/BMT‐Nf film modified GCE successfully applied for the oxygen reduction reaction in neutral pH (pH 7.0 PBS). The proposed film modified GCE successfully reduces the over potential and show well defined reduction peaks for the detection of dissolved oxygen using cyclic voltammetry (CV) and rotating disc voltammetry (RDE). The film also applied for the detection of dissolved oxygen using electrochemical impedance spectroscopic studies (EIS).
A Contribution to the Study of the Adsorption of s‐Triazine Herbicides on Glassy Carbon Electrodes by Differential‐Capacity Measurements
Authors: Pintado S. , Amaro R. Rodríguez , Mellado J. M. Rodríguez 
Published: February 2010

AbstractMeasurements of differential capacity vs. potential have been made for a series of s‐triazine herbicides at different concentrations. In all cases the decrease in capacity was independent of the applied potential, so the adsorption is also independent of the potential. From the measurements it can be established that the adsorption follows Langmuir type isotherms. Adsorption constants were obtained for the different herbicides at 25 °C (simetryn, simazine, terburyn and prometon) as well as those to simetryn at different temperatures, from which the adsorption enthalpy of this herbicide was calculated being its value of 17.5 kJ mol−1.
Lable‐Free Electrochemical DNA Sensor Based on Gold Nanoparticles/Poly(neutral red) Modified Electrode
Authors: Zhang Keying , Zhang Yuzhong 
Published: February 2010

AbstractWe present a new strategy for the label‐free electrochemical detection of DNA hybridization based on gold nanoparticles (AuNPs)/poly(neutral red) (PNR) modified electrode. Probe oligonucledotides with thiol groups at the 5‐end were covalently linked onto the surface of AuNPs/PNR modified electrode via S‐Au binding. The hybridization event was monitored by using differential pulse voltammetry (DPV) upon hybridization generates electrochemical changes at the PNR‐solution interface. A significant decrease in the peak current was observed upon hybridization of probe with complementary target ssDNA, whereas no obvious change was observed with noncomplementary target ssDNA. And the DNA sensor also showed a high selectivity for detecting one‐mismatched and three‐mismatched target ssDNA and a high sensitivity for detecting complementary target ssDNA, the detection limit is 4.2×10−12 M for complementary target ssDNA. In addition, the DNA biosensor showed an excellent reproducibility and stability under the DNA‐hybridization conditions.
Impact of Epstein–Barr virus in the clinical evolution of patients with classical Hodgkin's lymphoma in Brazil
Authors: Souza Eni M. , Baiocchi Otávio C. G. , Zanichelli Maria A. , Alves Antonio C. , Assis Marianne G. , Eiras Daniel P. , Dobo Cristine , Oliveira José S. R. 
Published: February 2010

AbstractIntroductionClassical Hodgkin's Lymphoma (cHL) has been frequently associated with Epstein–Barr virus (EBV), which can be found in a latent pattern in Reed‐Sternberg (RS) cells. However, the impact of the presence of EBV in RS cells and its prognosis are still controversial. We analysed the presence of EBV in RS cells and its influence in the clinical evolution of patients with cHL treated in two public hospitals in the city of São Paulo, Brazil.Materials and MethodsWe selected 97 patients with cHL from 1994 to 2004. Patients were only included in this study if they had (1) >18 years, (2) negative HIV serology, (3) undergone similar chemotherapy protocols, (4) paraffin blocks available with enough material for systematic review and histological reclassification and for detection of EBV in RS cells by in situ hybridization and immunohistochemistry and (5) clinical, epidemiological and laboratorial parameters available after a thorough chart review.ResultsEBV was identified in 52.5% of the cases. Mixed cellularity (MC) subtype was more common in EBV‐related tumours (25.5%) (p = 0.005). There was no difference on age, gender, stage and the presence of B symptoms between the two groups. The presence of EBV did not influence event free survival (EFS) (p = 0.38) or overall survival (OS) (p = 0.80) with a median follow‐up of 80 months.ConclusionWe demonstrate that the prevalence of EBV‐related cHL in this Brazilian population is 52.5% and, that, the presence of EBV does not change the clinical evolution and OS of patients treated with similar chemotherapy protocols. Copyright © 2010 John Wiley & Sons, Ltd.
Pak1 and Pak2 are activated in recurrent respiratory papillomas, contributing to one pathway of Rac1‐mediated COX‐2 expression
Authors: Wu Rong , Abramson Allan L. , Symons Marc H. , Steinberg Bettie M. 
Published: February 2010

AbstractRecurrent respiratory papillomas are premalignant tumors of the airway caused by human papillomaviruses (HPVs), primarily Types 6 and 11. We had reported that respiratory papillomas overexpress the epidermal growth factor receptor (EGFR), the small GTPase Rac1 and cyclooxygenase‐2 (COX‐2), and have enhanced nuclear factor‐κB (NFκB) activation with decreased levels of IκB‐β but not IκB‐α. We also showed that EGFR‐activated Rac1 mediates expression of COX‐2 through activation of p38 mitogen‐activated protein kinase. We have now asked whether the p21‐activated kinases Pak1 or Pak2 mediate activation of p38 by Rac1 in papilloma cells. Pak1 and Pak2 were constitutively activated in vivo in papilloma tissue compared with normal epithelium, and Rac1 siRNA reduced the level of both phospho‐Pak1 and phospho‐Pak2 in cultured papilloma cells. Reduction in Pak1 and Pak2 with siRNA decreased the COX‐2 expression in papilloma cells, increased the levels of IκB‐β and reduced the nuclear localization of NF‐κB, but had no effect on p38 phosphorylation. Our studies suggest that Rac1 → Pak1/Pak2 → NFκB is a separate pathway that contributes to the expression of COX‐2 in HPV‐induced papillomas, independently of the previously described Rac1 → p38 → COX‐2 pathway.
Formulation and characterization of radio‐opaque conjugated in situ gelling materials
Authors: Blakely Brandon , Hoon Lee Bae , Riley Celeste , McLemore Ryan , Pathak Chandrashekhar P. , Vernon Brent L. 
Published: February 2010

AbstractX‐ray visibility is an integral design component of in situ gelling embolization systems for neurovascular treatment. The goals of this project included the synthesis and characterization of a unique intrinsically radio‐opaque in situ gelling material for neurovascular embolization. The gels formed using Michael‐Type Addition between pentaerythritol tetrakis 3‐mercaptopropionate (QT) thiols and poly(propylene glycol) diacrylate (PPODA) with the addition of the new material Iodobenzoyl poly(ethylene glycol) acrylate (IPEGA), a radio‐opaque agent, synthesized successfully as confirmed with 1H NMR. The PPODA and IPEGA were mixed using a syringe coupler with QT and buffer at pH 11 for 90 seconds. Gel mixes were weighed to provide equal molar thiols and acrylate groups, changing the present acrylate‐bearing compounds wt % ratios from 100 PPODA: 0 IPEGA, 90:10, 80:20, 70:30, 60:40, 50:50, and 0:100. Formulations with 10% and above of IPEGA were X‐ray visible. Rheology showed that increasing the amount of IPEGA decreased the storage. Kinetic FT‐IR studies indicate that the amphiphilic nature of the PEG backbone increased the reaction rate of the phase segregated reactants. Second order reaction constant modeling showed a change in initial reaction rate from 0.0029 to 0.0187 (M sec)−1 from the 10% to 50% IPEGA formulations respectively. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010
Vertebral morphology in aromatase inhibitor–treated males with idiopathic short stature or constitutional delay of puberty
Authors: Hero Matti , Toiviainen-Salo Sanna , Wickman Sanna , Mäkitie Outi , Dunkel Leo 
Published: February 2010

Abstract
Aromatase inhibitors (AIs), blockers of estrogen biosynthesis, delay bone maturation and therefore are used increasingly to promote growth in children and adolescents with growth disorders. The effects of treatment on skeletal health are largely unknown. Since estrogen deficiency is associated with various detrimental skeletal effects, we evaluated in this cross-sectional posttreatment study vertebral body morphology, dimensions and endplates, and intervertebral disks by the use of magnetic resonance imaging (MRI) in two cohorts of males previously treated with the AI letrozole or placebo. Males with idiopathic short stature received treatment with letrozole or placebo for 2 years during prepuberty or early puberty; males with constitutional delay of puberty received letrozole or placebo in combination with low-dose testosterone for 1 year during early or midpuberty. In males with idiopathic short stature, mild vertebral body deformities were found in 5 of 11 (45%) letrozole-treated subjects, whereas in the placebo group no deformities were detected (p = .01). In the cohort of males with constitutional delay of puberty, a high prevalence of endplate and intervertebral disk abnormalities was observed in both the letrozole- and the placebo-treated groups. We conclude that AI therapy during prepuberty or early puberty may predispose to vertebral deformities, which probably reflect impaired vertebral body growth rather than impaired bone quality and compression fractures. If AIs are used in growth indications, follow-up of vertebral morphology is indicated. © 2010 American Society for Bone and Mineral Research
Evidence that obesity does not influence the vitamin D-endocrine system in blacks
Authors: Epstein Sol , Dr. Bell Norman H. , Shary Judith , Shaw Sheryl , Greene Anne , Oexmann Mary Joan 
Published: February 2010

Abstract
As compared to nonobese white men and women, age-matched nonobese black subjects and obese white individuals show alterations in the vitamin D–endocrine system that are characterized by increases in mean serum immunoreactive parathyroid hormone (PTH), serum 1,25-dihydroxyvitamin D [1,25-(OH)2D], and urinary cyclic adenosine 3,5-monophosphate (cAMP) and by decreases in mean serum 25-hydroxyvitamin D (25 OHD) and in urinary calcium. Thus, both groups show secondary hyperparathyroidism which is associated with increased renal tubular reabsorption of calcium and increased renal synthesis of 1,25-(OH)2D. In view of these findings, studies were conducted in 10 obese black subjects (3 men and 7 women) and in 12 nonobese black individuals (7 men and 5 women), ranging in age from 20 to 35 yr, to determine whether obesity influences the vitamin D–endocrine system in blacks. Body weight averaged 99 ± 4 kg in the obese and 73 ± 3 kg in the nonobese subjects (p &lt; .001). All of them were hospitalized on a metabolic ward and were given a constant daily diet containing 400 mg of calcium, 900 mg of phosphorus, 110 meq of sodium, 65 meq of potassium, and 18 meq of magnesium. Whereas mean serum Gla protein was significantly higher in the obese than in the nonobese black subjects (23 ± 4 vs. 14 ± 2 ng/ml, p &lt; .05), mean serum total calcium, ionized calcium, phosphorus, magnesium, immunoreactive PTH by two different radioimmunoassays (399 ± 23 vs. 312 ± 26 pg/ml and 357 ± 26 vs. 392 ± 27 pg/ml), 25 OHD (5 ± 1 vs. 6 ± 1 ng/ml) and 1,25(OH)2D (43 ± 3 vs. 41 ± 3 pg/ml) were the same in the two groups. Also, mean urinary calcium (105 ± 13 vs. 101 ± 14 mg/d), phosphorus, sodium, potassium, magnesium and cAMP (3.12 ± 0.24 vs. 3.11 ± 0.47 nM/dl GF) and creatinine clearance were the same in the obese and nonobese black men and women. The results indicate that obesity does not produce alterations in the vitamin D–endocrine system that are over and above the changes present in nonobese black men and women.
The effect of ipriflavone (TC-80) on bone resorption in tissue culture
Authors: Tsuda Masao , Kitazaki Tadashi , Ito Toshio , Fujita Takuo 
Published: February 2010

Abstract
The fetal long bone culture system developed by Raisz for the assessment of bone resorption was modified to improve the sensitivity, by using radii and ulnae separately, based on the observation of the consistently higher release of 45Ca from the radii than ulnae. Effects of ipriflavone (TC-80), an isoflavonoid derivative currently under clinical trial for its effect on osteoporosis, on bone resorption were examined in this new system. Ipriflavone and its metabolites (5 out of 6) at 10 μg/ml or more inhibited basal 45Ca release from bones. The inhibitory effects were still demonstrated in the presence of submaximal concentration of parathyroid hormone (12.5 ng/ml). The effect of ipriflavone on bone resorption was apparently not due to its toxicity on bone cells, since the inhibition was reversible.
Clonal differences in prostaglandin synthesis among osteosarcoma cell lines
Authors: Dr. Rodan Sevgi B. , Wesolowski Gregg , Rodan Gideon A. 
Published: February 2010

AbstractThis study compares the metabolism of [14C]-arachidonic acid between PGE2 synthesizing (ROS 17/2.8) and nonsynthesizing (ROS 25/1) osteosarcoma cell lines. In both cell lines: (a) 90% of [14C]-arachidonic acid was taken up at 24 h. (b) More than 90% of the label was associated with phospholipids. (c) [14C]-arachidonic acid was rapidly taken up by phosphatidylcholine which reached the highest specific activity around 5 h while the labeling of other phospholipids was still increasing at 24 h. (d) Twenty-four hours after addition of [14C]-arachidonic acid only 4% of the label was associated with triacylglycerols in ROS 25/1 and 0.3% in ROS 17/2.8 cells. The calcium ionophore A23187 enhanced the release of [14C]-arachidonic acid from phospholipids in the PGE synthesizing osteoblastic cells (ROS 17/2.8 and 2/3) but had no effect in nonosteoblastic cells (ROS 24/1 and 25/1). ROS 17/2.8 and 2/3 cells converted the released arachidonic acid as well as exogeneously added arachidonic acid into PGE2. PGE2 synthesis depended on arachidonic acid concentration.Among bone resorbing agents, parathyroid hormone and 1,25(OH)2D3 had no effect on PGE synthesis, whereas thrombin and rabbit serum stimulated PGE2 production. The effect of rabbit serum was abolished by heat inactivation.The findings of this study indicate that the difference in PGE production between the osteoblastic and nonosteoblastic osteosarcoma cells are due mainly to differences in arachidonic acid conversion to PGE2.
Abnormal calcium metabolism caused by increased circulating 1,25-dihydroxyvitamin D in a patient with rheumatoid arthritis
Authors: Gates Sherman , Shary Judith , Turner Russell T. , Wallach Stanley , Bell Norman H. 
Published: February 2010

Abstract
A 35-year-old white male with rheumatoid arthritis who had developed hypercalcemia, hypercalciuria, and nephrolithiasis was found to be abnormally sensitive to vitamin D as a result of lack of regulation of circulating 1,25-dihydroxyvitamin D (1,25-(OH)2D). An increase in daily intake of vitamin D from 10 μg (400 units) per day to 50 μg (2000 units) per day produced an abnormal elevation in serum 1,25-(OH)2D, hypercalcemia, and hypercalciuria which were corrected by prednisone. Serum 25-hydroxyvitamin D initially was abnormally low, and increased with vitamin D to values which were in the low normal range. There were significant positive correlations between serum 1,25-(OH)2D (p &lt; .05) and serum calcium and between serum 1,25-(OH)2D and urinary calcium (p &lt; .05). Serum immunoreactive parathyroid hormone, initially in the lower range of normal, decreased further during hypercalcemia. A radiograph of the chest, gallium scan, and serum angiotensin-converting enzyme activity were normal. No granulomas or evidence of lymphoma were found in biopsies of the liver and of several lymph nodes. It is concluded that the abnormal calcium metabolism in this patient resulted from increased circulating 1,25-(OH)2D and that the defect in vitamin D metabolism was not related to sarcoidosis, other granulomatous disease, Hodgkin's disease, or lymphoma. The relationship, if any, of the abnormal metabolism of vitamin D and calcium to rheumatoid arthritis remains to be established.
Effects of human recombinant CSF-GM and highly purified CSF-1 on the formation of multinucleated cells with osteoclast characteristics in long-term bone marrow cultures
Authors: MacDonald B. R. , Mundy G. R. , Clark S. , Wang E. A. , Kuehl T. J. , Stanley E. R. , Roodman G. D. 
Published: February 2010

Abstract
Several studies have suggested that the osteoclast is derived from a mononuclear precursor which is found in bone marrow. We have developed a system for studying the formation of osteoclast-like multinucleated cells in long-term bone marrow culture of baboon cells. Recombinant human CSF-GM and highly purified CSF-1, both of which stimulate the proliferation of monocyte/macrophage precursors, were found to increase the number of osteoclast-like cells formed in long-term bone marrow culture. CSF-GM stimulated multinucleated cell formation more consistently than CSF-1. The subsequent addition of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) to cultures initially treated with CSF-GM or CSF-1 further increased multinucleated cell formation. Autoradiographic studies indicate that CSF stimulated multinucleated cell formation by increasing the proliferation of the precursor cell, and that the potentiating effect of 1,25-(OH)2D3 was caused by fusion of the increased numbers of precursors. These studies suggest that the interaction of locally produced colony-stimulating factors with circulating calcium regulating hormones may be important in the control of osteoclast formation and bone resorption.