bluuebunny/crossref_metadata_2025 huggingface dataset:
Robustness to Failure of Assumptions of Tests for a Common Slope Amongst Several Allometric Lines – A Simulation Study
Authors: Warton David I.
Published: August 2006

In allometry, researchers are commonly interested in estimating the slope of the major axis or standardized major axis (methods of bivariate line fitting related to principal components analysis). This study considers the robustness of two tests for a common slope amongst several axes. It is of particular interest to measure the robustness of these tests to slight violations of assumptions that may not be readily detected in sample datasets. Type I error is estimated in simulations of data generated with varying levels of nonnormality, heteroscedasticity and nonlinearity. The assumption failures introduced in simulations were difficult to detect in a moderately sized dataset, with an expert panel only able to correct detect assumption violations 34–45% of the time.

While the common slope tests were robust to nonnormal and heteroscedastic errors from the line, Type I error was inflated if the two variables were related in a slightly nonlinear fashion. Similar results were also observed for the linear regression case. The common slope tests were more liberal when the simulated data had greater nonlinearity, and this effect was more evident when the underlying distribution had longer tails than the normal. This result raises concerns for common slopes testing, as slight nonlinearities such as those in simulations are often undetectable in moderately sized datasets. Consequently, practitioners should take care in checking for nonlinearity and interpreting the results of a test for common slope. This work has implications for the robustness of inference in linear models in general. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interaction of synthetic peptides corresponding to the scaffolding domain of Caveolin‐3 with model membranes
Authors: Sowmya Bekshe L. , Jagannadham M. V. , Nagaraj Ramakrishnan
Published: August 2006

Caveolin‐1 and ‐3 are among the few proteins in which the functional domains are contiguous and modular. The interaction of synthetic peptides spanning the scaffolding domain of caveolin‐3 with model membranes has been investigated. The peptides include the scaffolding domain, the aromatic and positively charged residues at the C‐terminal end of this domain as well as deletion of three amino acids TFT, observed in certain patients with limb girdle muscular dystrophy. All of the peptides appear to be peripherally bound to the bilayer surface. However, no preferential binding to sphingomyelin and cholesterol‐containing lipid vesicles was observed. Deletion of TFT appears to affect the association with lipid vesicles compared with the native sequence. Association with lipids decreases considerably when TFT as well as the aromatic‐rich segment YWFYR, which occurs at the extreme C‐terminus of the scaffolding domain, are deleted. © 2006 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 84: 615–624, 2006

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Mutational analysis of protein solubility enhancement using short peptide tags
Authors: Kato Atsushi , Maki Kosuke , Ebina Teppei , Kuwajima Kunihiro , Soda Kunitsugu , Kuroda Yutaka
Published: August 2006

Protein aggregation is a common phenomenon. The preparation of highly concentrated protein samples, typically required for biophysical measurements, often involves a time consuming and tedious testing of solvent conditions for improving protein solubility. Here, in a systematic analysis, we have determined the increase in solubility upon the addition of SEP‐tags (solubility enhancement peptide tags) containing, one, three, and five lysines or arginines (or six arginines) to either the N or C terminus of our low solubility model protein, bovine pancreatic trypsin inhibitor variant, BPTI‐22 (a BPTI variant containing 22 alanines). As anticipated, the BPTI‐22 solubility increased in direct relation to the number of charged residues contained in the SEP‐tag, and without altering either the activity or the structure of the protein. The largest solubility increases were of 4.2‐, 4.8‐, and 6.2‐folds produced by the addition, at the C terminus, of five lysine (BPTI‐22‐C5K), five and six arginine residues (BPTI‐22‐C5R and BPTI‐22‐C6R), respectively. The increased solubility of the tagged BPTI‐22 yielded higher quality NMR spectra (hetero single quantum correlation HSQC spectra; with respect of the signal‐to‐noise and line shapes) in a much shorter time than for the untagged BPTI‐22. Furthermore, tagged samples remained soluble for over ten days, as observed by their HSQC spectra. We believe that lysine‐ and arginine‐based SEP‐tags may provide an effective and versatile method for enhancing protein solubility. © 2006 Wiley Periodicals, Inc. Biopolymers 85: 12–18, 2007.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Selective modification of surface‐exposed thiol groups in Trigonopsis variabilisD‐amino acid oxidase using poly(ethylene glycol) maleimide and its effect on activity and stability of the enzyme
Authors: Slavica Anita , Dib Iskandar , Nidetzky Bernd
Published: August 2006

Covalent modification of purified Trigonopsis variabilis D‐amino acid oxidase using maleimide‐activated poly(ethylene glycol) 5000 yielded a stable bioconjugate in which three surface‐exposed cysteine side chains were selectively derivatized. Compared with the native enzyme, the PEGylated variant displayed substantially (≈3.3‐fold) slowed dissociation rate of FAD cofactor at 50°C, and this caused a twofold thermostabilization of the enzyme activity. The stability under reaction conditions at 30°C was also markedly enhanced in the PEG‐oxidase conjugate. PEGylation did not affect steady‐state kinetic parameters for oxidative deamination of D‐methionine when 2,6‐dichloroindophenol replaced dioxygen as the cosubstrate while it caused a ninefold decrease in substrate catalytic efficiency for the dioxygen‐dependent reaction. Biotechnol. Bioeng. 2007;96: 9–17. © 2006 Wiley Periodicals, Inc.
Effect of Suspended Liposomes on Hydrodynamic and Oxygen Transfer Properties in a Mini‐Scale External Loop Airlift Bubble Column
Authors: Yoshimoto M. , Momodomi C. , Fukuhara H. , Fukunaga K. , Nakao K.
Published: August 2006

The circulating liquid velocity, gas holdup, bubble size distribution, and liquid phase oxygen transfer coefficient were measured in a mini‐scale external loop airlift bubble column (MELBC) with the liquid volume suspending enzyme‐free liposomes of varying diameters. These values were compared to those for liposome‐free MELBC, normal bubble column (NBC), and a larger scale airlift column. The liposomes suspended in the MELBC are incorporated into the liquid film around the bubbles, leading to the development of a foam layer, where the incorporated liposomes exert negligible effect on the oxygen transfer in the film.
Absorption and Stripping of CO2 with a Molten Salt Slurry in a Bubble Column at High Temperature
Authors: Terasaka K. , Suyama Y. , Nakagawa K. , Kato M. , Essaki K.
Published: August 2006

A novel slurry bubble column in which a lithium silicate as a CO2 absorbent is suspended in a molten salt at high temperature was proposed. To confirm the feasibility of the proposed system, the effects of the CO2 feed rate into the slurry bubble column, the quantity of absorbent, and the suspension concentration on the performance of the CO2 recovery were investigated. The proposed system could rapidly absorb and strip CO2 by thermal swinging. Moreover, no reduction of the CO2 recovery performance by the repeated use of the absorbent was observed.
Axial Distribution of Oxygen Concentration in Different Airlift Bioreactor Scales: Mathematical Modeling and Simulation
Authors: Znad H. , Tokumura M. , Kawase Y.
Published: August 2006

Steady and unsteady state oxygen concentration distributions in the liquid and gas phases along the axial direction of different airlift bioreactor scales have been simulated for various gas flow rates and oxygen consumption rates by applying the axial dispersion model to the riser and the downcomer, and a complete mixing model for the top (separator) and the bottom sections of the bioreactor. The results show that the dissolved oxygen concentration is very low at the lower part of the downcomer when the rate of oxygen consumption by microorganisms is very high. Furthermore, the shorter (small) bioreactor shows relatively more uniform axial dissolved oxygen concentrations than the longer (large) bioreactor, due to the effect of the hydrostatic pressure along the bioreactor. One of the most important geometric factors for mass transfer is the reactor height, which dominates the mean pressure and thus influences the saturation concentration and mass transfer driving force. The presented model can be applied for modeling and scale‐up of practical airlift bioreactors.
Chemisorptive Removal of Carbon Dioxide from Process Streams Using a Reactive Bubble Column with Simultaneous Production of Usable Materials
Authors: Petrov P. , Ewert G. , Röhm H.‐J.
Published: August 2006

In the context of attempts to improve the protection of the environment, a novel process where the carbon dioxide reacts rapidly with almost 100 % conversion under mild conditions, is proposed. The chemisorptive process takes place in a slurry bubble column which operates with countercurrent flow, utilizing special solutions of primary long chain amines in a nonaqueous media. The product obtained is insoluble and separated by filtration. Because of its molecular structure, this product possesses tenside properties and can be used as an industrial additive. Typically the liquid phase consists of a mixture of hexadecylamine (C16H33NH2) or dodecylamine (C12H25NH2) in various concentrations with methanol or other alcohols as the solvent. Numerous parameters have been studied including different column heights, gas inlet compositions, gas flow rates and solvent type. Efficiencies of up to 99 % are achievable for CO2 absorption with methanol as the solvent. The second solvent examined, isopropanol, shows lower CO2 conversion rates. This can be attributed to its physical properties, mainly higher viscosity and hence, smaller mass transfer coefficient. In order to simulate real gas conditions, the influence of other sour gases, e.g., SO2 was also investigated experimentally. Because of coabsorption of the two gases, the CO2 efficiency was lower in this instance. In both solvents, the absorption efficiency with respect to SO2 is more than 99 % due to its high solubility and reactivity. A complex mathematical model has been developed and applied to describe the mass and enthalpy transport in the reactive bubble column.
Turbulent Enhancement of Mass Transfer in Bubble Plumes
Authors: Schaub F. , Pluschkell W.
Published: August 2006

An experimental method was developed for measuring the mass transfer in water/air/carbon dioxide systems with pH‐probes. Measurements of the mass transfer were made with respect to the parameters of desorption in bubble plumes. The investigations show a linear increase of the mass transfer with the gas flow rate. Furthermore, the mass transfer rate depends on the nozzle diameter, but not on that of the vessel. The mass transfer rates of the momentum dominated near field, of the buoyancy dominated far field, and of the free surface were separated experimentally. The probability density functions of the bubble size were determined with a photographic method as a function of the gas inlet conditions. Comparing the experimental results for the buoyancy dominated far field of the bubble plume with a basic microkinetic approach demonstrates that the turbulent flow does not increase the mass transfer by more than 10–20 %. Thus, a turbulence factor of 2–3 in order to establish consistency between the theoretical considerations and the experimental results, as described elsewhere in the literature, is not required.
Development and validation of nomograms for predicting residual tumor size and the probability of successful conservative surgery with neoadjuvant chemotherapy for breast cancer
Authors: Rouzier Roman , Pusztai Lajos , Garbay Jean‐Remi , Delaloge Suzette , Hunt Kelly K. , Hortobagyi Gabriel N. , Berry Donald , Kuerer Henry M.
Published: August 2006

BACKGROUND

Neoadjuvant chemotherapy (NACT) increases the likelihood that breast conservation therapy for breast cancer patients will be successful. There is no available nomogram to predict breast conservation after NACT. The aim of the current study was to develop and validate nomograms for predicting residual tumor size and probability of a patient becoming eligible for breast conservation surgery after NACT.

METHODS

A total of 1147 patients treated at M. D. Anderson Cancer Center (Houston, TX) and the Institut Gustave Roussy (Villejuif, France) who received anthracycline with or without paclitaxel NACT were included in the analysis. Clinicopathologic data from 1 series were used to construct logistic regression models for breast conservation and residual tumor size < 3 cm after NACT and were validated on an independent series.

RESULTS

The discrimination and the calibration of the nomogram for predicting the probability of residual tumor size < 3 cm after anthracycline‐based NACT were good when applied to the validation set (concordance index = 0.79; U‐index = 10−3). The discrimination of the nomogram for predicting eligibility for breast conservation therapy was also good (concordance index = 0.67). However, the calibration had to be adjusted to take into account global rates of breast conservation surgery. A second nomogram adapted to preoperative chemotherapy regimens containing paclitaxel was established. The concordance index of the nomogram for predicting breast conservation was 0.71 (P< 10−6) for the independent dataset and the calibration was also good. The confrontation of both nomograms showed that predictions were highly correlated (r = 0.97), suggesting that eligibility for breast conservation therapy was independent of the preoperative chemotherapy regimen used.

CONCLUSIONS

Nomograms were developed for breast cancer patients who received NACT to predict residual tumor size and whether the patient would thus become eligible for breast conservation therapy. These tools may be useful when counseling patients about treatment options, and a web‐based interface is now available to help guide patients and physicians in these decisions. Cancer 2006. © 2006 American Cancer Society.
Viable malignant germ cell tumor in the postchemotherapy retroperitoneal lymph node dissection specimen
Authors: Spiess Philippe E. , Brown Gordon A. , Pisters Louis L. , Liu Ping , Tu Shi‐Ming , Evans James G. , Kamat Ashish M. , Black Peter , Tannir Nizar M.
Published: August 2006

BACKGROUND

The presence of viable tumor in the surgical specimen after postchemotherapy retroperitoneal lymph node dissection (PC‐RPLND) is associated with an increased risk of disease progression. The objective of this study was to determine whether the presence of viable tumor in the surgical specimen could be predicted.

METHODS

Between 1980 and 2003, 236 patients underwent PC‐RPLND for clinical Stage IIA or III nonseminomatous germ cell tumors (NSGCT). The authors retrospectively reviewed the medical records of those patients for pertinent clinical and treatment‐related outcomes. A multivariate logistic regression analysis was used to evaluate whether clinical parameters were capable of predicting the presence of viable tumor in the surgical specimen.

RESULTS

International Germ Cell Consensus Classification (IGCCC) risk categories could be assigned to 218 patients, with 101 patients in the good‐risk category, 32 patients in the intermediate‐risk category, and 85 patients in the poor‐risk category. The incidence of viable tumor in the good‐risk, intermediate‐risk, and poor‐risk categories was similar (17.8%, 15.6%, and 15.3%, respectively); however, the risk categories predicted disease‐specific and recurrence‐free survival (P= .022 andP< .0001, respectively). On multivariate analysis, an elevated serum α‐fetoprotein (AFP) level prior to PC‐RPLND (P= .05) and the size of the retroperitoneal mass on pathology review (P= .02) were predictive of viable tumor in the surgical specimen.

CONCLUSIONS

Although IGCCC risk categories were correlated with disease‐related outcomes, the risk groups had similar incidences of viable tumor. Elevated serum AFP levels prior to surgery and the size of the retroperitoneal mass in the resected specimen may help to predict viable tumor in the PC‐RPLND specimen. Cancer 2006. © 2006 American Cancer Society.
Biochemical and clinical significance of the posttreatment prostate‐specific antigen bounce for prostate cancer patients treated with external beam radiation therapy alone
Authors: Horwitz Eric M. , Levy Lawrence B. , Thames Howard D. , Kupelian Patrick A. , Martinez Alvaro A. , Michalski Jeffrey M. , Pisansky Thomas M. , Sandler Howard M. , Shipley William U. , Zelefsky Michael J. , Zietman Anthony L. , Kuban Deborah A.
Published: August 2006

BACKGROUND.

The posttreatment prostate‐specific antigen (PSA) bounce phenomenon has been recognized in at least 20% of all patients treated with radiation. The purpose of the current report was to determine if there was a difference in biochemical and clinical control between the bounce and nonbounce (NB) patients using pooled data on 4839 patients with T1‐2 prostate cancer treated with external beam radiation therapy (RT) alone at 9 institutions between 1986 and 1995.

METHODS.

The median follow‐up was 6.3 years. A posttreatment PSA bounce was defined by a minimal rise of 0.4 ng/mL over a 6‐month follow‐up period, followed by a drop in PSA level of any magnitude. Endpoints included no biochemical evidence of disease (bNED) failure (BF) (ASTRO definition), distant failure (DF), cause‐specific failure (CSF), and overall survival (OS). Patients were stratified by pretreatment PSA, Gleason score, T stage, age, dose, and risk group.

RESULTS.

In all, 978 (20%) patients experienced at least 1 posttreatment PSA bounce. Within 3 subgroups (risk group, pretreatment PSA, and age), statistically significant differences of remaining bounce‐free were observed on univariate analysis. Patients < 70 years had a 72% chance of remaining bounce‐free at 5 years compared with 75% for older patients (P = .04). The NB patients had 72% bNED control at 10 years compared with 58% for the bounce patients. The effect of a bounce remained statistically significant on multivariate analysis (P < .0001). No statistically significant difference in DF, CSF, or OS was observed.

CONCLUSIONS.

Patients treated with external beam radiation therapy alone who experience a posttreatment PSA bounce have increased risk of BF. However, this did not translate into a difference in clinical failure with the available follow‐up in the current study. Cancer 2006. © 2006 American Cancer Society.
Rituximab combined with cladribine or with cladribine and cyclophosphamide in heavily pretreated patients with indolent lymphoproliferative disorders and mantle cell lymphoma
Authors: Robak Tadeusz , Smolewski Piotr , Cebula Barbara , Szmigielska‐Kaplon Anna , Chojnowski Krzysztof , Blonski Jerzy Z.
Published: August 2006

BACKGROUND

In vitro studies have shown synergistic or additive interactions between rituximab and purine nucleoside analogues. The results of recent clinical trials seem to confirm these preclinical observations.

METHODS

For the current study, the authors evaluated the feasibility, efficacy, and toxicity of combined regimens that consisted of either rituximab plus cladribine (2‐CdA) (the RC regimen) or RC plus cyclophosphamide (the RCC regimen) in the treatment of patients with heavily pretreated, indolent lymphoid malignancies. Fifty‐four adult patients with recurrent or refractory, low‐grade non‐Hodgkin lymphoma (LG‐NHL) and B‐cell chronic lymphocytic leukemia (B‐CLL) were treated according to the RC/RCC regimens. The RC protocol consisted of intravenous rituximab at a dose of 375 mg/m2 on Day 1 and 2‐CdA at a dose of .12 mg/kg per day on Days 2 through 6. The RCC protocol consisted of rituximab at a dose of 375 mg/m2 on Day 1, 2‐CdA at a dose of 0.12 mg/m2 on Days 2 through 4, and intravenous cyclophosphamide at a dose of 250 mg/m2 per day on Days 2 to 4. The RC/RCC courses were repeated at 4‐week intervals.

RESULTS

Thirty‐three patients with B‐CLL, 12 patients with LG‐NHL and 9 patients with mantle cell lymphoma (MCL) entered the study. Thirty‐three patients (61%) had recurrent disease after prior therapy, and 21 patients (39%) had refractory disease. Thirty‐one patients were treated on the RC regimen, and 23 patients were treated on the RCC regimen. Six patients (11%) achieved a complete response, and 33 patients (60%) achieved a partial response. The median failure‐free survival of responders was 10.5 months. The treatment revealed tolerability, with episodes of severe neutropenia (Grade 3 and 4 [according to World Health Organization criteria]) observed in 6 patients (11%), episodes of Grade 3 and 4 infections observed in 11 patients (20%), and episodes of Grade 3‐4 thrombocytopenia observed in 4 patients (7%).

CONCLUSIONS

The RC and RCC regimens were highly effective and well tolerated modalities of treatment in heavily pretreated patients with indolent lymphoproliferative disorders. Cancer 2006. © 2006 American Cancer Society.
Prevention of severe menorrhagia in oncology patients with treatment‐induced thrombocytopenia by luteinizing hormone‐releasing hormone agonist and depo‐medroxyprogesterone acetate
Authors: Meirow Dror , Rabinovici Jaron , Katz Daniela , Or Reuven , Ben‐Yehuda Dina
Published: August 2006

BACKGROUND

Menorrhagia is a serious complication in young female oncology patients who suffer from severe thrombocytopenia during myelosuppressive treatment. To the authors' knowledge, little is known regarding the incidence of this complication or the effectiveness of possible therapies for its prevention.

METHODS

In this retrospective clinical study, after a thorough gynecologic evaluation, young female oncology patients with regular menstrual cycles undergoing myelosuppressive treatments received either depo‐medroxyprogesterone acetate (DMPA), or D‐tryptophan‐6‐luteinizing hormone‐releasing hormone depot treatment (gonadotropin‐releasing hormone agonist [GnRH‐a]), or no treatment before the administration of myelosuppresive chemotherapy. Only patients who later developed severe thrombocytopenia (<25,000 platelets per μL) were included in the study. Daily blood counts, menorrhagia, nonvaginal bleeding episodes, and the need for blood products, gynecologic consultations, and other medical interventions were determined.

RESULTS

Of 101 women with cancer who met the inclusion criteria, 42 patients received DMPA, 39 patients received GnRH‐a, and 20 patients remained untreated. The mean duration (± standard deviation) of severe thrombocytopenia was 24.76 ± 23.6 days. Four patients were not included because of significant gynecologic pathologies. General bleeding from nongynecologic sites was similar for all groups and was not associated with vaginal bleeding. Severe or moderate menorrhagia was documented in none of the 39 women who received GnRH‐a, in 9 patients (21.4%) who received DMPA, and in 9 untreated patients (40%; P = .02). Fewer calls for urgent gynecologic consultations were documented in the GnRH‐a group compared with the untreated group (P < .0001).

CONCLUSIONS

Female patients undergoing myelosupressive therapy are at high risk of developing significant menorrhagia during prolonged, severe thrombocytopenia. Pretreatment gynecologic evaluation can detect significant pelvic pathologies. GnRH‐a treatment effectively prevented menorrhagia, whereas DMPA administration was less effective. Cancer 2006. © 2006 American Cancer Society.
P48 is a predictive marker for outcome of postoperative interferon‐α treatment in patients with hepatitis B virus infection‐related hepatocellular carcinoma
Authors: Qian Yong‐Bing , Zhang Ju‐Bo , Wu Wei‐Zhong , Fang Hong‐Bin , Jia Wei‐Dong , Zhuang Peng‐Yuan , Zhang Bo‐Heng , Pan Qi , Xu Yang , Wang Lu , Tang Zhao‐You , Sun Hui‐Chuan
Published: August 2006

BACKGROUND.

Postoperative interferon‐α (IFN‐α) therapy improved survival in patients with hepatitis B virus (HBV)‐related hepatocellular carcinoma (HCC). The identification of predictive markers of outcome will help to select patients who are most likely to benefit from treatment.

METHODS.

An immunohistochemical study of P48 was performed on specimens that were collected from patients in a randomized trial who received postoperative IFN‐α therapy (Group 1; n = 80 patients) and who did not receive postoperative IFN‐α therapy (Group 2; n = 75 patients). Positive P48 expression was graded as ≥20% positive cells in 1 sample.

RESULTS.

Eighty‐one patients were positive for P48, and 74 patients were negative for P48. The clinicopathologic data were comparable between patients with P48‐negative and P48‐positive staining. Disease‐free survival (DFS) and overall survival (OS) in P48‐positive patients were better than that in P48‐negative patients in Group 1 (DFS, P = .036; OS, P = .014), however, DFS and OS did not differ between patients with positive and negative P48 in Group 2. OS in P48‐positive patients from Group 1 was better than that in patients with P48‐positive patients from Group 2 (OS, P = .001) but did not differ when P48 was negative. In Group 1, the risk factors for DFS were cirrhosis and P48 staining, and the risk factors for OS were tumor differentiation and P48 staining. Receiver operating curve analysis indicated that, in the first 2 years of DFS, combined cirrhosis and P48 had good predictive accuracy; and, in the first 4 years of OS, combined tumor differentiation and P48 had good predictive accuracy.

CONCLUSIONS.

P48 was useful as a predictive marker of outcome after postoperative IFN‐α treatment in patients with HBV‐related HCC. Cancer 2006. © 2006 American Cancer Society.
Cyclodimethylsiloxane (Me2SiO)m (m = 3–6) Ring Transformations on Reactions with AgSbF6; Crystal Structure of Ag(Me2SiO)7SbF6
Authors: Decken Andreas , LeBlanc Francis Arthur , Passmore Jack , Wang Xinping
Published: August 2006

The reaction of Dm (D = Me2SiO, m = 3–6) with silver hexafluoroantimonate in liquid SO2 affords a mixture of AgDnSbF6 (n = 6–8) complexes. Upon the addition of CH3CN, Ag+‐directed ring transformations are effected, which allows for the isolation of neat Dn (n = 6–8). The AgDn+ cations are rare examples of Lewis acid donor complexes of silicon ethers and Ag+ oxygen donor complexes, and their isolation implies that numerous metal cation cyclosiloxanes can be prepared from readily available starting materials.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Nonlinear, Resonance‐Stabilized Pseudohalides: From Alkali Methanides to Ionic Liquids of Methanides
Authors: Brand Harald , Liebman Joel F. , Schulz Axel , Mayer Peter , Villinger Alexander
Published: August 2006

New 1‐ethyl‐3‐methylimidazolium (EMI) salts [EMI][X] (X = [HC(NO2)(CN)]–, [C(NO2)(NO)(CN)]–, [HC(NO)2]– and [HC(NO2)2]–) and 1‐n‐butyl‐3‐methylimidazolium (BMI) salts [BMI][Y] (Y = [C(CN)3]– and [C(NO2)(NO)(CN)]–) were prepared and characterized. Different synthetic routes to these new resonance‐stabilized methanide‐based ionic liquids starting either from the explosive silver salts (except from Ag[C(CN)3]) or the easily accessible potassium salts have been described. The melting points of all new salts are lower than 100 °C, in fact, most of them are ionic liquids at room temperature. These strongly colored ionic liquids (besides [BMI][C(CN)3] which is colorless) are neither heat nor shock sensitive, are thermally stable up to over 52 °C ([EMI][C(NO2)(NO)(CN)]) and 270 °C ([BMI][C(CN)3]) and can be prepared in large quantities. The structure and bonding of resonance‐stabilized methanides ([CR1R2R3]– with, R1,2,3 = H, NO2, NO, and CN) is discussed on the basis of experimental and theoretical data. X‐ray data of Cs+[HC(NO2)(CN)]–, K+[HC(NO2)2]–, [EMI]+[C(NO2)(NO)(CN)]–, and [Me4N]+[C(NO2)(NO)(CN)]– reveal almost planar anions with strong cation···anion interactions in the alkali methanides resulting in three‐dimensional network structures in the solid state. Only weak interionic interactions are found for the ammonium salts. As shown by different theoretical approaches (charge transfer, resonance energies and NLMO delocalization) resonance effects occur in all three classes of methanides (NO2‐, NO‐, and CN‐substituted), however, the magnitude of such effect strongly differs depending on the degree of substitution. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Synthesis of Photoactive α‐Mannosides and Mannosyl Peptides and Their Evaluation for Lectin Labeling
Authors: Wiegand Michaela , Lindhorst Thisbe K.
Published: August 2006

Adhesion to the glycosylated surface of eukaryotic cells, mediated by lectins for example, plays an important role in inflammation and other cellular processes of living organisms. To elucidate the mechanisms involved in the adhesion to cell surfaces and their biological consequences, the investigation of the molecular interactions between carbohydrate recognition domains of lectins and their ligands is of relevance. In this work, we have selected the photoaffinity labeling technique for the exploration of the ligand binding to mannose‐specific lectins, particularly the α‐mannose‐specific adhesin FimH, which is expressed at the tips of type 1 fimbriae of Escherichia coli bacteria. We have designed and synthesized a series of mannosides and glycopeptides derived thereof that are equipped with a photoactive functional group. It was our goal to compare the properties and labeling potencies of different types of photolabile residues, and therefore, photolabeled mannosides with an azide, a diazirine, and a benzophenone moiety were synthesized. Their crosslinking activity was investigated by photolysis in the presence of six different amino acids and with three model peptides, angiotensin II, PTHIKWGD, and pentaglycine as well. The crosslinked adducts so obtained were analyzed by mass spectrometry. In addition, difunctionalized mannosides were sought that contained a photolabel and a biotin marker to facilitate the isolation and the eventual identification, respectively, of the photolabeled peptides and proteins. To realize this concept, we have employed orthogonally functionalized glycoamino acid building blocks, which could be utilized as scaffold molecules for the synthesis of our bifunctional target molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Protection from radiation‐induced mitochondrial and genomic DNA damage by an extract of Hippophae rhamnoides
Authors: Shukla Sandeep Kumar , Chaudhary Pankaj , Kumar Indracanti Prem , Samanta Namita , Afrin Farhat , Gupta Manju Lata , Sharma Upendra Kumar , Sinha Arun Kumar , Sharma Yogendra Kumar , Sharma Rakesh Kumar
Published: August 2006

Hippophae rhamnoides or seabuckthorn is used extensively in Indian and Tibetan traditional medicine for the treatment of circulatory disorders, ischemic heart disease, hepatic injury, and neoplasia. In the present study, we have evaluated the radioprotective potential of REC‐1001, a fraction isolated from the berries of H. rhamnoides. Chemical analysis of the extract indicated that REC‐1001 was ∼68% by weight polyphenols, and contained kaempferol, isorhamnetin, and quercetin. The effect of REC‐1001 on modulating radiation‐induced DNA damage was determined in murine thymocytes by measuring nonspecific nuclear DNA damage at the whole genome level using the alkaline halo assay and by measuring sequence/gene‐specific DNA damage both in nuclear DNA (β‐globin gene) and in mitochondrial DNA using a quantitative polymerase chain reaction. Treatment with 10 Gy resulted in a significant amount of DNA damage in the halo assay and reductions in the amplification of both the β‐globin gene and mitochondrial DNA. REC‐1001 dose‐dependently reduced the amount of damage detected in each assay, with the maximum protective effects observed at the highest REC‐1001 dose evaluated (250 μg/ml). Studies measuring the nicking of naked plasmid DNA further established the radioprotective effect of REC‐1001. To elucidate possible mechanisms of action, the antioxidant properties and the free‐radical scavenging activities of REC‐1001 were evaluated. REC‐1001 dose‐dependently scavenged radiation‐induced hydroxyl radicals, chemically‐generated superoxide anions, stabilized DPPH radicals, and reduced Fe3+ to Fe2+. The results of the study indicate that the REC‐1001 extract of H. rhamnoides protects mitochondrial and genomic DNA from radiation‐induced damage. The polyphenols/flavonoids present in the extract might be responsible for the free radical scavenging and DNA protection afforded by REC‐1001. © 2006 Wiley‐Liss, Inc.
Screening and characterization of variant Theta‐class glutathione transferases catalyzing the activation of ethylene dibromide to a mutagen
Authors: Josephy P. David , Taylor Patricia L. , Vervaet Gaby , Mannervik Bengt
Published: August 2006

Ethylene dibromide (EDB) is a widespread environmental pollutant and mutagen/carcinogen. Certain Theta‐class glutathione transferases (GSTs), enzymes that catalyze the reaction of reduced glutathione (GSH) with electrophiles, activate EDB to a mutagen. Previous studies have shown that human GST T1‐1, but not rat GST T2‐2, activates EDB. We have constructed an E. coli lacZ reversion mutagenicity assay system in which expression of recombinant GST supports activation of EDB to a mutagen. Hexa‐histidine N‐terminal tagging of GST T1‐1 results in greatly enhanced expression of the recombinant enzyme and gives a lacZ strain that shows a mutagenic response to EDB at extremely low levels (∼1 ng EDB per plate). The hexa‐histidine‐tagged enzyme was purified in one step by Ni2+‐affinity chromatography. We applied the lacZ mutagenicity assay to the rapid screening of a library of variant GST Theta enzymes. Sequence variants with altered catalytic activities were identified, purified, and characterized. Environ. Mol. Mutagen., 2006. © 2006 Wiley‐Liss, Inc.
Co‐electrospun poly(lactide‐co‐glycolide), gelatin, and elastin blends for tissue engineering scaffolds
Authors: Li Mengyan , Mondrinos Mark J. , Chen Xuesi , Gandhi Milind R. , Ko Frank K. , Lelkes Peter I.
Published: August 2006

In this study, we describe composite scaffolds composed of synthetic and natural materials with physicochemical properties suitable for tissue engineering applications. Fibrous scaffolds were co‐electrospun from a blend of a synthetic biodegradable polymer (poly(lactic‐co‐glycolic acid), PLGA, 10% solution) and two natural proteins, gelatin (denatured collagen, 8% solution) and α‐elastin (20% solution) at ratios of 3:1:2 and 2:2:2 (v/v/v). The resulting PLGA–gelatin–elastin (PGE) fibers were homogeneous in appearance with an average diameter of 380 ± 80 nm, which was considerably smaller than fibers made under identical conditions from the starting materials (PLGA, 780 ± 200 nm; gelatin, 447 ± 123 nm; elastin, 1060 ± 170 nm). Upon hydration, PGE fibers swelled to an average fiber diameter of 963 ± 132 nm, but did not disintegrate. Importantly, PGE scaffolds were stable in an aqueous environment without crosslinking and were more elastic than those made of pure elastin fibers. To investigate the cytocompatibility of PGE, we cultured H9c2 rat cardiac myoblasts and rat bone marrow stromal cells (BMSCs) on fibrous PGE scaffolds. We found that myoblasts grew equally as well or slightly better on the scaffolds than on tissue‐culture plastic. Microscopic evaluation confirmed that myoblasts reached confluence on the scaffold surfaces while simultaneously growing into the scaffolds. Histological characterization of the PGE constructs indicated that BMSCs penetrated into the center of scaffolds and began proliferating shortly after seeding. Our results suggest that fibrous scaffolds made of PGE and similar biomimetic blends of natural and synthetic polymers may be useful for engineering soft tissues, such as heart, lung, and blood vessels. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Detailed analysis of myocardial motion in volunteers and patients using high‐temporal‐resolution MR tissue phase mapping
Authors: Jung Bernd , Föll Daniela , Böttler Petra , Petersen Steffen , Hennig Jürgen , Markl Michael
Published: August 2006

Purpose

To detect and investigate details in left ventricular (LV) motion patterns with a temporal resolution comparable to that of echocardiography.

Material and Methods

To assess global and regional myocardial motion in high temporal detail, respiratory‐gated MR phase‐contrast measurements with three‐directional velocity encoding (venc) were performed in 12 healthy volunteers and two patients with LV hypertrophy in basal, midventricular, and apical locations of the LV with a temporal resolution of 13.8 msec.

Results

The volunteer data revealed details in LV motion patterns that were known only from echocardiography. For all volunteers, characteristic myocardial motion patterns, such as triphasic global diastolic expansion, could be detected with high accuracy. One volunteer underwent an additional echocardiographic measurement in order to corroborate the complex motion features as measured by MRI. Patient examinations revealed substantial changes in diastolic function compared to motion patterns in healthy volunteers.

Conclusion

The proposed high‐temporal‐resolution velocity‐mapping technique provides previously undetectable information on LV performance, and is highly promising for the detection of local and global motion abnormalities in patients with disturbed LV performance, such as diastolic dysfunction. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Involvement of complement receptor 3 (CR3) and scavenger receptor in macrophage responses to wear debris
Authors: Rakshit Diptendu S. , Lim Jin T.E. , Ly Khanh , Ivashkiv Lionel B. , Nestor Bryan J. , Sculco Thomas P. , Purdue P. Edward
Published: August 2006

The ability of prosthetic wear debris to induce pro‐inflammatory responses in macrophages is widely appreciated, but little is known about the molecular mechanisms involved in particle recognition. Specifically, the nature of the cell surface receptors that interact with wear debris is poorly understood. Elucidating the identities of these receptors and how they interact with different types of wear debris are critical to understanding how wear debris initiates periprosthetic osteolysis. We examined the involvement of opsonization, complement receptor 3 (CR3), and scavenger receptor A (SRA), in responses to polymethylmethacrylate (PMMA) and titanium wear particles. Serum dependence of pro‐inflammatory responses to PMMA and titanium was tested, and serum proteins that adhered to these two types of particles were identified. Several serum proteins, including known opsonins such as C3bi and fibronectin, adhered to PMMA but not titanium, and serum was required for pro‐inflammatory signaling induced by PMMA, but not by titanium. Phagocytosis of PMMA and titanium by macrophages was demonstrated by flow cytometry. Blocking CR3 specifically inhibited phagocytosis of PMMA by macrophages, whereas blocking SRA specifically inhibited titanium uptake. Direct involvement of CR3 and SRA in cell–particle interaction was assessed by expression of these receptors in nonphagocytic HEK293 cells. CR3 specifically induced cell binding to PMMA particles and adhesion to PMMA‐coated plates, while SRA specifically induced binding to titanium particles and adhesion to titanium‐coated plates. Taken together, these results suggest involvement of opsonization, complement, and integrin receptors, including CR3 and fibronectin receptors, in PMMA action, and an involvement of scavenger receptors in responses to titanium. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 24:2036–2044, 2006
Morphological and Physical Properties of Triblock Copolymers of Methyl Methacrylate and 2‐Ethylhexyl Methacrylate
Authors: Eslami Hormoz , Zhu Shiping
Published: August 2006

Summary: Triblock copolymers of methyl methacrylate (MMA) and 2‐ethylhexyl methacrylate (EHMA) [that is, poly(MMA–EHMA–MMA)] were prepared by an emulsion atom‐transfer radical polymerization. The relationships of their structural, morphological, and physical properties were investigated. The latex particles had core‐shell morphologies and the block copolymers experienced phase separation. Small latex particles with a low number of cores could deform and wet silicon‐wafer surfaces, but the deformation of large latex particles was restricted by the internal two‐phase morphology of the particles. Latex casting produced continuous pinhole‐free films, in which hard poly(MMA) (PMMA) cores of different latex particles merged and provided interparticle connections. The morphology of solution‐cast films depended on block composition, solvent type, and film thickness. For all the prepared polymer samples, thick films cast in toluene had poly(EHMA) (PEHMA) materials at air surface, whereas those cast in tetrahydrofuran had a sponge‐like PMMA surface structure. Thin toluene‐cast films from P(MMA–EHMA–MMA) with the block degrees of polymerization ($\overline {DP}$) 200–930–200 showed spherical PMMA domains and those from 380–930–380 yielded a protruded worm‐like PMMA structure. The copolymer materials were coated on a glass surface for peeling tests. The films gave good hot‐melt adhesion properties when the $\overline {DP}$ of the PEHMA block was over 600. The peeling strength depended on the lengths of both PEHMA and PMMA blocks. The P(MMA–EHMA–MMA) sample with $\overline {DP} {\rm s}$ of 310–930–310 yielded the highest peeling strength of 7.4 kgf · inch−1. The developed material is demonstrated to be a good candidate for a solvent‐free, hot‐melt, pressure‐sensitive adhesives for special‐purpose applications such as medical tapes and labels.

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Effect of Bio‐Scavengers on the Curing Behavior and Bonding Properties of Melamine‐Formaldehyde Resins
Authors: Kim Sumin , Kim Hyun‐Joong , Kim Hee‐Soo , Lee Hwa Hyoung
Published: August 2006

Summary: The effects of bio‐scavengers on the formaldehyde emission, bonding strength, curing behavior, and thermal decomposition properties of MF resins for engineered flooring and adhesion for wood were investigated. Four varieties of bio‐scavengers, tannin powder, wheat flour, rice husk flour, and charcoal, were added to MF resin at 5 wt.‐%. To determine formaldehyde emission and bonding strength, we manufactured engineered floorings. MF‐charcoal was most effective in reducing formaldehyde emission because of its porous nature, but its bonding strength was decreased. Tannin powder and wheat flour, which contain more hydroxyl groups, showed higher bonding strength and curing degree than pure MF resin did. Although the hydroxyl groups of the bio‐scavengers were effective in reducing formaldehyde emission and improve bonding strength and curing degree, rice husk flour and charcoal behaved like inorganic substances, thereby disturbing the adhesion between MF resin and wood and thus reducing the bonding strength. In thermogravimetric analysis, MF‐tannin showed the highest thermal stability in the low‐temperature range from 100 to 300 °C.

Storage modulus (E′) of MF resin with various bio‐scavengers at a heating rate of 10 °C · min−1.

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Storage modulus (E′) of MF resin with various bio‐scavengers at a heating rate of 10 °C · min−1.
MP‐SAGE: A new MP‐RAGE sequence with enhanced SNR and CNR for brain imaging utilizing square‐spiral phase encoding and variable flip angles
Authors: Stöcker Tony , Shah N. Jon
Published: August 2006

The magnetization‐prepared rapid gradient‐echo (MP‐RAGE) sequence is well known and widely used for high‐resolution, structural brain MRI. Here we present a new version, termed magnetization‐prepared spiral acquisition gradient‐echo (MP‐SAGE), that employs interleaved square‐spiral phase‐encoding (PE) to take advantage of the 3D nature of the sequence. Resolution loss caused by point‐spread function (PSF) blurring is circumvented by the use of variable flip angle (VFA) radiofrequency (RF) pulses. The pulse train is calculated by means of an accurate new signal evolution theory that is derived from the extended phase graph (EPG) description. Phantom results show excellent agreement between theory and experiment for substances with relaxation times similar to those of human brain tissue. Both phantom and in vivo results show a strong enhancement of SNR and CNR compared to the standard MP‐RAGE in high‐resolution MRI. The benefits for brain tissue segmentation using images obtained with MP‐SAGE are shown. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Quantification of the pulse wave velocity of the descending aorta using axial velocity profiles from phase‐contrast magnetic resonance imaging
Authors: Yu Hsi‐Yu , Peng Hsu‐Hsia , Wang Jaw‐Lin , Wen Chih‐Yung , Tseng Wen‐Yih Isaac
Published: August 2006

The pulse wave velocity (PWV) of aortic blood flow is considered a surrogate for aortic compliance. A new method using phase‐contrast (PC)‐MRI is presented whereby the spatial and temporal profiles of axial velocity along the descending aorta can be analyzed. Seventeen young healthy volunteers (the YH group), six older healthy volunteers (the OH group), and six patients with coronary artery disease (the CAD group) were studied. PC‐MRI covering the whole descending aorta was acquired, with velocity gradients encoding the in‐plane velocity. From the corrected axial flow velocity profiles, PWV was determined from the slope of an intersecting line between the presystolic and early systolic phases. Furthermore, the aortic elastic modulus (Ep) was derived from the ratio of the brachial pulse pressure to the strain of the aortic diameter. The PWV increased from YH to OH to CAD (541 ± 94, 808 ± 184, 1121 ± 218 cm/s, respectively; P = 0.015 between YH and OH; P = 0.023 between OH and CAD). There was a high correlation between PWV and Ep (r = 0.861, P < 0.001). Multivariate analysis showed that age and CAD were independent risk factors for an increase in the PWV. Compared to existing methods, our method requires fewer assumptions and provides a more intuitive and objective way to estimate the PWV. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
Numerical simulation of substation grounding grids buried in both horizontal and vertical multilayer earth model
Authors: Li Zhong‐Xin , Fan Jian‐Bin , Chen Wei‐Jiang
Published: August 2006

In the simulation of quasi‐static electromagnetic fields produced by a point source located in both horizontal and vertical multilayer media, the conventional image method requires an infinite number of images to get an accurate solution, while the method of quasi‐static complex images needs only a few ones. Based on the method of quasi‐static complex images, the closed form of Green's function of a point source in both horizontal and vertical multilayer earth model is derived through matrix pencil (MP) approach. The fast convergent Galerkin's type of boundary element method (BEM) is taken to simulate and analyse a grounding system including floating electrode with any complicated structure, which can be located anywhere in horizontal or vertical multilayer earth model. Copyright © 2006 John Wiley & Sons, Ltd.