bluuebunny/crossref_metadata_2025_split huggingface dataset:
Using multiple cutpoints for the free‐to‐total prostate specific antigen ratio improves the accuracy of prostate cancer detection*
Authors: Hoffman Richard M. , Clanon David L. , Chavez Margarita , Peirce John C. 
Published: August 2002

AbstractBACKGROUNDUsing a single cutpoint for the free‐to‐total (F/T) prostate specific antigen (PSA) ratio loses important diagnostic information. We evaluated the performance of multiple F/T PSA cutpoints in detecting prostate cancer in men with nonspecific PSA values.METHODSWe extracted sensitivity and specificity data from 12 studies reporting on ≥30 cancer patients with PSA values between 2.0 and 10.0 ng/mL. We calculated stratum‐specific likelihood ratios (LR) and areas under the receiver operating characteristic (ROC) curves.RESULTSMultiple cutpoints for the F/T PSA ratio significantly increased the area under the ROC (0.70) compared with the single investigator‐selected cutpoint (0.62), P < 0.004. The LR for the most positive cutpoint stratum (2.62) was significantly higher than the LR for a positive test from the single cutpoint (1.36), P < 0.004.CONCLUSIONSUsing multiple cutpoints increased the discriminating power of the F/T PSA ratio and led to greater probability revisions in the most positive test‐result strata. Prostate 52:150–158, 2002. © 2002 Wiley‐Liss, Inc.
Reduction of human prostate tumor vascularity by the α1‐adrenoceptor antagonist terazosin
Authors: Keledjian Kaspar , Borkowski Andrew , Kim Grace , Isaacs John T. , Jacobs Stephen C. , Kyprianou Natasha 
Published: August 2002

AbstractBACKGROUNDWe previously demonstrated that the quinazoline‐derived a1‐adrenoceptor antagonists doxazosin and terazosin suppress prostate cancer growth via apoptosis induction. The aim of this study was to determine the potential effect of a1‐adrenoceptor antagonists on tumor vascularity of the human prostate.METHODSA total of 34 men with benign prostatic hyperplasia (BPH) who have been on terazosin treatment (for the obstructive symptoms) were pathologically diagnosed with prostate cancer following surgery. These patients were stratified according to the length of treatment periods with terazosin into two groups, 1 week–6 months, and 6–17 months. The control group consisted of prostatectomy specimens from 25 untreated prostate cancer patients undergoing surgery for localized disease. Formalin‐fixed, paraffin‐embedded prostate specimens were analyzed for apoptosis (TUNEL assay), cell proliferation (Ki‐67), microvessel density (MVD) (von Willebrand factor/Factor VIII), vascular endothelial growth factor (VEGF) expression, and prostate specific antigen (PSA) immunoreactivity.RESULTSA significant induction of apoptosis was observed among cancerous prostatic epithelial cells in the terazosin‐treated, as compared to the untreated prostate cancer specimens, while there was no significant change in the proliferative index of the same tumor cell populations after treatment. Furthermore, terazosin resulted in a significant decrease in prostate tissue MVD compared with the untreated group (P < 0.01), that correlated with the increased apoptotic index of the cancerous areas. Tissue PSA expression in the prostatic tumor foci was also markedly reduced after terazosin treatment, while no significant changes in VEGF expression were detected.CONCLUSIONSThese findings provide the first evidence that terazosin, a quinazoline‐based a1‐blocker decreases prostate tumor vascularity. Our study has significant clinical implications in identifying selected α1‐adrenoceptor antagonists as potential anti‐tumor agents with apoptotic and anti‐angiogenic effects in the human prostate that can be exploited for the treatment of advanced prostate cancer. Prostate 48:71–78, 2001. © 2001 Wiley‐Liss, Inc.
Molecular dynamics simulations of the acyl‐enzyme and the tetrahedral intermediate in the deacylation step of serine proteases
Authors: Topf Maya , Várnai Péter , Schofield Christopher J. , Richards W. Graham 
Published: August 2002

AbstractDespite the availability of many experimental data and some modeling studies, questions remain as to the precise mechanism of the serine proteases. Here we report molecular dynamics simulations on the acyl‐enzyme complex and the tetrahedral intermediate during the deacylation step in elastase catalyzed hydrolysis of a simple peptide. The models are based on recent crystallographic data for an acyl‐enzyme intermediate at pH 5 and a time‐resolved study on the deacylation step. Simulations were carried out on the acyl enzyme complex with His‐57 in protonated (as for the pH 5 crystallographic work) and deprotonated forms. In both cases, a water molecule that could provide the nucleophilic hydroxide ion to attack the ester carbonyl was located between the imidazole ring of His‐57 and the carbonyl carbon, close to the hydrolytic position assigned in the crystal structure. In the “neutral pH” simulations of the acyl‐enzyme complex, the hydrolytic water oxygen was hydrogen bonded to the imidazole ring and the side chain of Arg‐61. Alternative stable locations for water in the active site were also observed. Movement of the His‐57 side‐chain from that observed in the crystal structure allowed more solvent waters to enter the active site, suggesting that an alternative hydrolytic process directly involving two water molecules may be possible. At the acyl‐enzyme stage, the ester carbonyl was found to flip easily in and out of the oxyanion hole. In contrast, simulations on the tetrahedral intermediate showed no significant movement of His‐57 and the ester carbonyl was constantly located in the oxyanion hole. A comparison between the simulated tetrahedral intermediate and a time‐resolved crystallographic structure assigned as predominantly reflecting the tetrahedral intermediate suggests that the experimental structure may not precisely represent an optimal arrangement for catalysis in solution. Movement of loop residues 216–223 and P3 residue, seen both in the tetrahedral simulation and the experimental analysis, could be related to product release. Furthermore, an analysis of the geometric data obtained from the simulations and the pH 5 crystal structure of the acyl‐enzyme suggests that since His‐57 is protonated, in some aspects, this crystal structure resembles the tetrahedral intermediate. Proteins 2002;47:357–369. © 2002 Wiley‐Liss, Inc.
Substrate flow in catalases deduced from the crystal structures of active site variants of HPII from Escherichia coli
Authors: Melik‐Adamyan William , Bravo Jerónimo , Carpena Xavier , Switala Jack , Maté Maria J. , Fita Ignacio , Loewen Peter C. 
Published: August 2002

AbstractThe active site of heme catalases is buried deep inside a structurally highly conserved homotetramer. Channels leading to the active site have been identified as potential routes for substrate flow and product release, although evidence in support of this model is limited. To investigate further the role of protein structure and molecular channels in catalysis, the crystal structures of four active site variants of catalase HPII from Escherichia coli (His128Ala, His128Asn, Asn201Ala, and Asn201His) have been determined at ∼2.0‐Å resolution. The solvent organization shows major rearrangements with respect to native HPII, not only in the vicinity of the replaced residues but also in the main molecular channel leading to the heme distal pocket. In the two inactive His128 variants, continuous chains of hydrogen bonded water molecules extend from the molecular surface to the heme distal pocket filling the main channel. The differences in continuity of solvent molecules between the native and variant structures illustrate how sensitive the solvent matrix is to subtle changes in structure. It is hypothesized that the slightly larger H2O2 passing through the channel of the native enzyme will promote the formation of a continuous chain of solvent and peroxide. The structure of the His128Asn variant complexed with hydrogen peroxide has also been determined at 2.3‐Å resolution, revealing the existence of hydrogen peroxide binding sites both in the heme distal pocket and in the main channel. Unexpectedly, the largest changes in protein structure resulting from peroxide binding are clustered on the heme proximal side and mainly involve residues in only two subunits, leading to a departure from the 222‐point group symmetry of the native enzyme. An active role for channels in the selective flow of substrates through the catalase molecule is proposed as an integral feature of the catalytic mechanism. The Asn201His variant of HPII was found to contain unoxidized heme b in combination with the proximal side His–Tyr bond suggesting that the mechanistic pathways of the two reactions can be uncoupled. Proteins 2001;44:270–281. © 2001 Wiley‐Liss, Inc.
Toxico‐kinetics, recovery efficiency and microsomal changes following administration of deltamethrin to black Bengal goats
Authors: Juliet Sanis , Chakraborty Animesh K , Koley Kishori M , Mandal Tapan K , Bhattacharyya Anjan 
Published: August 2002

AbstractA study of the toxico‐kinetics, recovery percentage from different substrates, cytotoxicity and role of cytochrome P450 and b5 of liver microsome in the metabolism of deltamethrin were carried out in female black Bengal goat. The ALD50 value of deltamethrin in goat by intravenous route lies between 0.2 and 0.6 mg kg−1. Intravenous disposition kinetics using a dose of 0.2 mg kg−1 showed that the maximum blood concentration of deltamethrin was recorded at 0.5 min, followed by rapid decline, and a minimum concentration was detected at 6 min after administration. The following values were obtained : Vdarea 0.148 (± 0.02) litre kg−1; t1/2 (α) 0.22 (± 0.02) min; t1/2 (β) 2.17 (± 0.37) min; Kel 1.05 (± 0.24) min−1; AUC 4.30(± 0.45) µg min ml−1; ClB 0.05 (± 0.006) litre kg−1 min−1; T∼B 1.93 (± 0.58); fc 0.40(± 0.05). After 10 min, liver retained the maximum residue, and heart, adrenal gland, kidney, spleen, fat and brain also held the insecticide; liver, fat, heart and spleen retained residue after 30 min, and bone, liver and fat retained residue after 60 min of intravenous administration. Oral absorption of deltamethrin was poor and inconsistent, and approximately 65% of administered dose was recovered from faeces and gastrointestinal contents. The excretion of deltamethrin through urine was meagre, and only 0.01 and 0.013% of the administered dose was recovered after 3 and 5 days of oral administration respectively. All the tissues retained the residue after 3 days; while fat, rumen, reticulum, omasum, abomasum, large and small intestine and bone retained the residue after 5 days of oral administration; and the percentage recoveries were 1.73 and 0.027 respectively. Deltamethrin reduced the level of cytochrome P450 content of liver microsomal pellet of goat after 5 days of oral administration. Histopathological examination of liver, kidney, heart, spleen brain and lung sections of treated goats did not reveal any pathological changes.© 2001 Society of Chemical Industry
Evaluation of uncalibrated preferential flow models against data for isoproturon movement to drains through a heavy clay soil
Authors: Beulke Sabine , Brown Colin D , Dubus Igor G , Harris Graham 
Published: August 2002

AbstractThe uncalibrated predictive ability of four preferential flow models (CRACK‐NP, MACRO/MACRO_DB, PLM, SWAT) has been evaluated against point rates of drainflow and associated concentrations of isoproturon from a highly structured and heterogeneous clay soil in the south of England. Data were available for four plots for a number of storm events in each of three successive growing seasons. The mechanistic models CRACK‐NP and MACRO generally gave reasonable estimates of drainflow over the three seasons, but under‐estimated concentrations of isoproturon over a prolonged period in the first season and over‐estimated them in the two remaining seasons. CRACK‐NP simulated maximum concentrations of isoproturon over the first two events of each of the three seasons of 156, 527 and 24.4 µg litre−1, respectively, and matched the observed data (465, 65.1 and 0.65 µg litre−1) slightly better than MACRO (69.1, 566 and 58.5 µg litre−1). Automatic selection of parameters from soils information within MACRO_DB reduced the emphasis on preferential flow relative to the stand‐alone version of MACRO. This gave a poor simulation of isoproturon breakthrough and simulated maximum concentrations were 0, 50.1 and 35.1 µg litre−1, respectively. The capacity model PLM gave the best overall simulation of total drainflow for the first two events in each season, but over‐estimated concentrations of isoproturon (967, 808 and 51.3 µg litre−1). The simple model SWAT represented total drainflow reasonably well and gave the best simulation of maximum isoproturon concentrations (140, 80.2 and 8.2 µg litre−1). There was no clear advantage here in using the mechanistic models rather than the simpler models. None of the models tested was able to simulate consistently the data set, and uncalibrated modelling cannot be recommended for such artificially drained heavy clay soils.© 2001 Society of Chemical Industry
Corrosion fatigue reliability of aging aircraft structures
Authors: Mahadevan Sankaran , Shi Pan 
Published: August 2002

AbstractStructural integrity evaluation methods for aging aircraft are surveyed. Design approaches and programmes adopted by the aircraft industry to ensure structural safety are reviewed. Corrosion fatigue is the major failure mechanism affecting airframe integrity. Therefore, corrosion fatigue reliability analysis and life prediction methods are emphasized in detail. Probabilistic methods to simulate the total corrosion fatigue damage process and to estimate the reliability, considering both single‐site and multiple‐site damage, are studied. Application examples that illustrate the reliability evaluation of aircraft fuselage lap joints under corrosion and fatigue are discussed.
Compatibilized Ny6‐based blends as ­innovative packaging materials: ­determination of some important properties ­relevant to food contact application
Authors: Laurienzo P. , Malinconico M. , Volpe M. G. , Luongo D. , Ranieri V. , Scoponi M. 
Published: August 2002

AbstractChemical physical analysis, photo‐oxidative stability and lipid oxidation of innovative polymeric films based on blends of nylon 6 and ethylene‐co‐vinyl alcohol for use in food packaging have been investigated. Thermal mechanical analysis showed that the presence of an interfacial agent in the blend stabilized the films towards the action of permeants. Synergistic effects of the interfacial agent are reported with respect to UV photostability. Peroxide value (PV) was used to follow the oxidation of the olive oil, and for this parameter also the influence of the interfacial agent was clearly detected. Copyright © 2001 John Wiley & Sons, Ltd.
Simulated experimental design used to define the characteristic curves of car shock‐absorbers
Authors: Arcidiacono G. , Capitani R. , Vianello M. 
Published: August 2002

AbstractThis paper introduces a special ‘quality’ parameter on automotive perspective, i.e. the quality index in order to measure the customer satisfaction with car manoeuvrability. In particular, it describes how the characteristic setting curves of a car shock‐absorber can be optimized using subjective customer assessment of three categories of perception: handling, steering quality and ride‐comfort. These, called manoeuvrability indices, were used to represent the assessment of customer satisfaction with car manoeuvrability. The characteristic curves for each shock‐absorber setting were defined using parameters which uniquely determined their shape. Subsequent analysis was carried out using simulated experimental design which adopts a numeric model of vehicle simulation thereby enabling experimental costs to be reduced. This analysis made it possible to ascertain which setting parameter values provided the best compromise among the three categories of required performance. A codified method of optimization was then developed. This method, which includes the three categories of perception, will be extended to all new projects. Copyright © 2001 John Wiley & Sons, Ltd.
Phase I control charts for independent Bernoulli data
Authors: Borror Connie M. , Champ Charles W. 
Published: August 2002

AbstractPhase I Shewhart p, np and runs of conforming charts are investigated. The performance of these charts are assessed using the probability of a false alarm. As with other Phase I Shewhart charts, the probability of a false alarm increases as the number, m, of samples increases for a fixed sample size, n. For a fixed value of m, the probability of at least one signal decreases as the sample size n increases. The probability of a signal for a runs of conforming chart depends on the number of samples m. Like the p and np charts, as m increases the probability of a false alarm increases. Unlike the p and np charts, the false alarm rate for a runs of conforming chart does not depend on the in‐control value of p. Copyright © 2001 John Wiley & Sons, Ltd.
High level ab initio and density functional theory calculations of the dissociation energies, ionization energies, geometrical variations, and vibrational modes of ground and excited CO2, CO2+, and CO22+
Authors: Jalbout Abraham F. 
Published: August 2002

AbstractThe potential energy surface of CO22+ ( 3Σg−) is investigated with HF, MP2, MP4, CBS‐Q, G1, G2MP2, G2, G3B3, and B3LYP/6‐311++G(3df,3pd) methods. Density functional theory shows the lowest dissociation channel of this compound to be the formation of CO+ ( 2Σ+)+O+ ( 4Su) and to have a barrier of around 2 eV as well as a dissociation energy of around −3.2 eV. Thus we propose that with enough correlation it is possible to accurately predict the energies of dissociation and barrier widths and heights to test for the stability of a particular molecular species. We also propose a refinement of current understanding by observing HOMO–LUMO gaps, Lowdin and Mulliken bond orders (to test for bond orbital overlap and hence qualitatively describe bonding and fragmentation in these complexes) and predicted spectrum for such studies as ZEKE spectroscopy (to study cationic states) and REMPI (to study the first excited states) of these class of molecules and, we hope, provide future insight into larger and more interesting systems. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Using theozymes for designing transition‐state analogs for the intramolecular aldol reaction of δ‐diketones
Authors: Arnó Manuel , Domingo Luis R. 
Published: August 2002

AbstractTwo theozymes for the intramolecular aldol reaction of δ‐diketones have been studied using ab initio methods. The presence of both acid/base residues favors several steps of the aldol reaction. The appropriate positioning of these residues can accelerate one of two diastereromeric reaction pathways, the catalyzed aldol reaction being highly stereoselective. Analysis of the geometrical parameters, charge distribution, and the shape of molecular electrostatic potential for the corresponding acid/base catalyzed transition structure allows us to design adequate transition‐state analogs to favor a reactive channel of this intramolecular aldol reaction. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 83: 338–347, 2001
Density functional study of small Nin clusters, with n=2–6, 8, using the generalized gradient approximation
Authors: Michelini M. C. , Pis Diez R. , Jubert A. H. 
Published: August 2002

AbstractResults of a systematic study of the geometry, electronic structure, magnetic, and vibrational properties of small nickel clusters Nin, with n=2–6, 8, within the framework of the generalized gradient approximation of the density functional theory are presented in this work. Emphasis is on the increasing number of stable conformers found when the cluster size increases. Some discussion on how the lower vibrational frequencies could help in the experimental elucidation of the ground states is provided. Finally, a comparison between experimental and calculated average magnetic moments per atom is presented. © 2001 John Wiley & Sons, Inc. Int J Quant Chem, 2001
Theoretical studies on heats of formation for cubylnitrates using density functional theory B3LYP method and semiempirical MO methods
Authors: Zhang Ji , Xiao Jijun , Xiao Heming 
Published: August 2002

AbstractThe heats of formation (HOF) have been calculated for all the 21 cubylnitrate compounds using the semiemprical molecular orbital (MO) methods (MINDO/3, MNDO, AM1, and PM3) and for 8 of 21 cubylnitrates containing 1–4 ONO2 groups using the density functional theory (DFT) method at the B3LYP/6‐31G* level by means of designed isodesmic reactions. The cubane cage skeletons in cubylnitrate molecules have been kept in setting up isodesmic reactions to produce more accurate and reliable results. It is found that there are good linear relationships between the HOFs of the 8 cubylnitrates calculated using B3LYP/6‐31G* and two semiempirical MO (PM3 and AM1) methods, and the linear correlation coefficients of PM3 and AM1 methods are 0.9901 and 0.9826, respectively. Subsequently, the accurate HOFs at B3LYP/6‐31G* level of other 13 cubylnitrates containing 4–8 ONO2 groups are obtained by systematically correcting their PM3‐calculated HOFs. Compared with noncaged nitrates, all the 21 cubylnitrates have high heats of formation implying that they may be very powerful energetic materials and have highly exploitable value. The relationship between the HOFs and the molecular structures of cubylnitrates has been discussed. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001
Neural network modeling of physical properties of chemical compounds
Authors: Kozioł J. 
Published: August 2002

AbstractThree different models relating structural descriptors to normal boiling points, melting points, and refractive indexes of organic compounds have been developed using artificial neural networks. A newly elaborated set of molecular descriptors was evaluated to determine their utility in quantitative structure–property relationship (QSPR) studies. Applying two data sets containing 190 amines and 393 amides, neural networks were trained to predict physical properties with close to experimental accuracy, using the conjugated gradient algorithm. Obtained results have shown a high predictive ability of learned neural networks models. The fit error for the predicted properties values compared to experimental data is relatively small. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 84: 117–126, 2001
Third‐order nonlinear optical properties of dendritic molecular aggregates: Effects of fractal architecture
Authors: Nakano M. , Fujita H. , Takahata M. , Kiribayashi S. , Yamaguchi K. 
Published: August 2002

AbstractWe investigate the microscopic third‐order nonlinear optical properties, i.e., the second hyperpolarizabilities (γ), of two different sizes of molecular aggregates with a dendritic, i.e., Bethe‐lattice, structure. One possesses a nonfractal structure, while the other has a fractal structure. The aggregate is treated in a two‐exciton model composed of two‐state monomers coupled to each other by the dipole–dipole interaction. The off‐resonant γ of the aggregates are calculated by the numerical Liouville approach, including relaxation effects. The total γ value is partitioned into the contribution of virtual exciton generation, and its spatial contribution to γ is analyzed in relation to the virtual excitation processes in the perturbation theory. It is found that the intermolecular‐interaction effect enhances both one‐ and two‐exciton‐generation contributions, while the relaxation effect reduces those, although the one‐ and two‐exciton‐generation contributions have mutually opposite signs. From the comparison of spatial contributions to γ between the nonfractal and fractal aggregates, an enhancement of the contribution to γ from the periphery to the core is observed in the fractal structure, while such a feature is not observed in the nonfractal structure. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001