bluuebunny/crossref_metadata_2025_split huggingface dataset:
Aromatase inhibition affects testosterone‐induced masculinization of song and the neural song system in female canaries
Authors: Fusani Leonida , Metzdorf Reinhold , Hutchison John B. , Gahr Manfred 
Published: December 2002

AbstractSongbirds have a specialized steroid‐sensitive network of brain nuclei, the song system, for controlling song. Most nuclei of the song system express androgen receptors, and the sensory‐motor integration nucleus High Vocal Center (HVC) alone also expresses estrogen receptors. Apart from expressing estrogen receptors in the vocal control system, songbirds are unique among birds because they have high concentrations of the estrogen‐synthesizing enzyme aromatase in the neostriatum surrounding HVC. However, the role of estrogen in controlling the development of the song structure has been scarcely investigated. In this work, we show that blocking the production of estrogen during testosterone‐induced song motor development in adult female canaries alters the song pattern compared to control females treated with testosterone only. These effects were correlated with inhibition of the expression of estrogen‐sensitive genes, such as brain‐derived nerve growth factor, in HVC. The expression of the ATP‐synthase gene, an indicator of cell activity, in HVC, and the size of HVC, were not affected by the treatment. Our results provide the first example of estrogen‐sensitive mechanisms controlling the structural features of adult birdsong. © 2002 Wiley Periodicals, Inc. J Neurobiol 54: 370–379, 2003
Domain decomposition for model heterogeneous anisotropic problem
Authors: Kwak D. Y. , Nepomnyaschikh S. V. , Pyo H. C. 
Published: December 2002

Abstract The main focus of this paper is to suggest a domain decomposition method for finite element approximations of elliptic problems with anisotropic coefficients in domains consisting of anisotropic shape rectangles. The theorems on traces of functions from Sobolev spaces play an important role in studying boundary value problems of partial differential equations. These theorems are commonly used for a priori estimates of the stability with respect to boundary conditions, and also play very important role in constructing and investigating effective domain decomposition methods. The trace theorem for anisotropic rectangles with anisotropic grids is the main tool in this paper to construct domain decomposition preconditioners. Copyright © 2002 John Wiley & Sons, Ltd.
Study of slabstock flexible polyurethane foams based on varied toluene diisocyanate isomer ratios
Authors: Aneja Ashish , Wilkes Garth L. , Rightor Edward G. 
Published: December 2002

AbstractThe morphological features of three flexible slabstock polyurethane foams based on varied contents of 2,4 and 2,6 toluene diisocyanate (TDI) isomers are investigated. The three commercially available TDI mixtures, that is, 65:35 2,4/2,6 TDI, 80:20 2,4/2,6 TDI, and 100:0 2,4/2,6 TDI were used. The foams were characterized at different length scales with several techniques. Differences in the cellular structure of the foams were noted with scanning electron microscopy. Small‐angle X‐ray scattering was used to demonstrate that all three foams were microphase‐separated and possessed similar interdomain spacings. Transmission electron microscopy revealed that the aggregation of the urea phase into large urea‐rich regions decreased systematically on increasing the asymmetric TDI isomer content. Fourier transform infrared spectroscopy showed that the level of bidentate hydrogen bonding of the hard segments increased with the 2,6 TDI isomer content. Differential scanning calorimetry and dynamic mechanical analysis (DMA) were used to note changes in the soft‐segment glass‐transition temperature of the foams on varying the diisocyanate ratios and suggested that the perfection of microphase separation was enhanced on increasing the 2,6 TDI isomer content. The preceding observations were used to explain why the foam containing the highest content of the symmetric 2,6 TDI isomer exhibited the highest rubbery storage modulus, as measured by DMA. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 258–268, 2003
Permeability, permselectivity, and penetrant‐induced plasticization in fluorinated polyimides studied by positron lifetime measurements
Authors: Shimazu Akira , Miyazaki Tukasa , Katayama Shigeru , Ito Yasuo 
Published: December 2002

AbstractThe ortho‐positronium (o‐Ps) lifetime τ3 and its intensity I3 in various fluorinated polyimides were determined by the positron annihilation technique and were studied with the spin–lattice relaxation time T1 and the propylene permeability, solubility, diffusivity, and permselectivity for propylene/propane in them. τ3, I3, and the distribution of τ3 changed when the bulky moieties in the polyimides were changed. The polyimides, having both large τ3 and I3 values, exhibited a short T1 and a high permeability with a low permselectivity. The propylene permeability and diffusivity were exponentially correlated with the product of I3 and the average free‐volume hole size estimated from τ3. In highly plasticized states induced by the sorption of propylene, the permeability increased with the propylene pressure in excellent agreement with the change in the free‐volume hole properties probed by o‐Ps. The large and broad distribution of the free‐volume holes and increased local chain mobility for the 2,2‐bis(3,4‐decarboxyphenyl) hexafluoropropane dianhydride‐based polyimides are thought to be important physical properties for promoting penetrant‐induced plasticization. These results suggest that o‐Ps is a powerful probe of not only the free‐volume holes but also the corresponding permeation mechanism and penetrant‐induced plasticization phenomenon. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 308–318, 2003
Structure and properties of the mesophase of syndiotactic polystyrene. II. Effect of stepwise extraction on the preparation of the mesophase
Authors: Rani D. Amutha , Yamamoto Y. , Mohri S. , Sivakumar M. , Tsujita Y. , Yoshimizu H. 
Published: December 2002

AbstractIn this study, a novel stepwise extraction method has been examined. The guest molecules housed between the helices of the clathrate δ form of syndiotactic polystyrene can be removed completely with this method. A systematic study of the preparation of a solvent‐free mesophase (emptied clathrate) membrane, its helical and residual solvent contents, and its structural transformations has been performed. In this first attempt, an enhancement in the TTGG helical content has been observed in the extracted membrane, and a conceptual mechanism is proposed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 269–273, 2003
Crystallization and melting of narrow composition distribution polyethylenes: Investigation and implications of crystal thickening
Authors: Mirabella Francis M. 
Published: December 2002

AbstractThe crystal structure produced during the isothermal crystallization of polyethylene (PE) copolymers with a broad range of comonomer concentrations was determined by the measurement of the melting endotherms directly after crystallization. PE copolymers with higher concentrations of short‐chain branches (≥10 branches per 1000 total carbon atoms) exhibited strong resistance to crystal thickening during isothermal crystallization. Negligible thickening, estimated to be only about 0.1 nm in 10 min of isothermal crystallization, was observed. The side‐chain branches apparently acted as limiting points of chain incorporation into the crystals, which exhibited great resistance to the modification of their position, that is, crystal thickening. Even with long periods (up to 8 h) of isothermal storage, crystal thickening was very small or negligible, about 0.3 nm. The crystal thickness was calculated from differential scanning calorimetry data. The behavior of copolymers with lower branching concentrations and the unbranched PE homopolymer was quite different from that of the copolymers with higher branching. Polymers with low or no branching exhibited the initial crystallization of a thinner crystal population, which thickened substantially with increasing time. The thickening observed for these lower or unbranched polymers was an order of magnitude larger, that is, 1.6–2.0 nm in 10 min of isothermal crystallization. Copolymers with higher concentrations of branching had relatively short sequence lengths of ethylene units between branch points, and this resulted in strong control over the crystal thickness by the branch points and great resistance to crystal thickening, even with long times of isothermal crystallization. Copolymers with low concentrations of branching had relatively long sequence lengths of ethylene units between branch points, and this resulted in little control over the crystal thickness by the branch points and rapid crystal thickening upon isothermal crystallization. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 235–246, 2003
Reconfiguration issues of future mobile software radio platforms
Authors: Laddomada Massimiliano 
Published: December 2002

AbstractThe evolution in the semiconductor industry leading to constant increase in the clock speeds and increase in device density and the advent of reconfigurable hardware have paved the way to the creation of a new generation of very agile reprogrammable communication systems generically known as Software Radio (SR) platforms. SR uses a mix of fixed and programmable and/or reconfigurable hardware entities for the implementation of radio transceiver functions capable of commanding the RF (Radio Frequency) spectrum used for wireless communications. While many articles have addressed the general architecture and features of such platforms, the literature on the mechanics of reconfiguring such units is rather scarce. This paper addresses the issue of reconfigurability for the SR platform. We look at a variety of techniques that may be employed to reconfigure the SR platform, list advantages and disadvantages of each, and address some of the questions that arise in the context of standardization efforts that may be needed to render such units truly universal in scope and in application. Copyright © 2002 John Wiley & Sons, Ltd.
Channel‐adaptive techniques in wireless communications: an overview
Authors: Cianca Ernestina , De Luise Aldo , Ruggieri Marina , Prasad Ramjee 
Published: December 2002

AbstractThe concept of adaptivity is of paramount importance in the design of future communication systems, in which a careful exploitation of the limited available resources (bandwidth, power, etc.) is required. The potential of channel‐adaptive transmission has been already recognized 30 years ago, but it did not receive much interest at that time. In the last decade, the advent of feasible software radio systems, and hence, the availability of fast flexible and reconfigurable transceivers has renewed interest in adaptive techniques, which include adaptive modulation and coding, adaptive antennas and adaptive equalization techniques. This paper focuses on adaptive modulation and adaptive error control mechanisms. Basic concepts are highlighted and an overview on the achieved results and new trends in this research area are presented. Some results from information theory are also presented, which show the limitations of these techniques and motivate further research on the practical and design issues that have to be addressed to enable performance to reach close to the theoretical limit. Copyright © 2002 John Wiley & Sons, Ltd.
In Vitro Drug Interaction Modeling of Combinations of Azoles with Terbinafine against ClinicalScedosporium prolificansIsolates
Authors: Meletiadis Joseph , Mouton Johan W. , Meis Jacques F. G. M. , Verweij Paul E. 
Published: December 2002

ABSTRACTThe in vitro interaction between terbinafine and the azoles voriconazole, miconazole, and itraconazole against five clinicalScedosporium prolificansisolates after 48 and 72 h of incubation was tested by a microdilution checkerboard (eight-by-twelve) technique. The antifungal effects of the drugs alone and in combination on the fungal biomass as well as on the metabolic activity of fungi were measured using a spectrophotometric method and two colorimetric methods, based on the lowest drug concentrations showed 75 and 50% growth inhibition (MIC-1 and MIC-2, respectively). The nature and the intensity of the interactions were assessed using a nonparametric approach (fractional inhibitory concentration [FIC] index model) and a fully parametric response surface approach (Greco model) of the Loewe additivity (LA) no-interaction theory as well as a nonparametric (Prichard model) and a semiparametric response surface approaches of the Bliss independence (BI) no-interaction theory. Statistically significant synergy was found between each of the three azoles and terbinafine in all cases, although with different intensities. A 27- to 64-fold and 16- to 90-fold reduction of the geometric mean of the azole and terbinafine MICs, respectively, was observed when they were combined, resulting in FIC indices of <1 to 0.02. Using the MIC-1 higher levels of synergy were obtained, , which were more consistent between the two incubation periods than using the MIC-2. The strongest synergy among the azoles was found with miconazole using the BI-based models and with voriconazole using the LA-based models. The synergistic effects both on fungal growth and metabolic activity were more potent after 72 h of incubation. Fully parametric approaches in combination with the modified colorimetric method might prove useful for testing the in vitro interaction of antifungal drugs against filamentous fungi.
Steady-State Pharmacokinetics of Amprenavir Coadministered with Ritonavir in Human Immunodeficiency Virus Type 1-Infected Patients
Authors: Goujard Cecile , Vincent Isabelle , Meynard Jean-Luc , Choudet Nathalie , Bollens Diane , Rousseau Cyril , Demarles Didier , Gillotin Catherine , Bidault Roselyne , Taburet Anne-Marie 
Published: December 2002

ABSTRACT

The protease inhibitor (PI) ritonavir is used as a strong inhibitor of cytochrome P450 3A4, which boosts the activities of coadministered PIs, resulting in augmented plasma PI levels, simplification of the dosage regimen, and better efficacy against resistant viruses. The objectives of the present open-label, multiple-dose study were to determine the steady-state pharmacokinetics of amprenavir administered at 600 mg twice daily (BID) and ritonavir administered at 100 mg BID in human immunodeficiency virus type 1 (HIV-1)-infected adults treated with different antiretroviral combinations including or not including a nonnucleoside reverse transcriptase inhibitor (NNRTI). Nineteen patients completed the study. The steady-state mean minimum plasma amprenavir concentration (
C
min,ss
) was 1.92 μg/ml for patients who received amprenavir and ritonavir without an NNRTI and 1.36 μg/ml for patients who received amprenavir and ritonavir plus efavirenz. For patients who received amprenavir-ritonavir without an NNRTI, the steady-state mean peak plasma amprenavir concentration (
C
max,ss
) was 7.12 μg/ml, the area under the concentration-time curve from 0 to 10 h (AUC
0-10
) was 32.06 μg · h/ml, and the area under the concentration-time curve over a dosing interval (12 h) at steady-state (AUC
ss
) was 35.74 μg · h/ml. Decreases in the mean values of
C
min,ss
(29%),
C
max,ss
(42%), AUC
0-10
(42%), and AUC
ss
(40%) for amprenavir occurred when efavirenz was coadministered with amprenavir-ritonavir. No unexpected side effects were observed. As expected, coadministration of amprenavir with ritonavir resulted in an amprenavir
C
min,ss
markedly higher than those previously reported for the marketed dose of amprenavir. When amprenavir-ritonavir was coadministered with efavirenz, amprenavir-ritonavir maintained a mean amprenavir
C
min,ss
above the mean 50% inhibitory concentration of amprenavir previously determined for both wild-type HIV-1 isolates and HIV-1 strains isolated from PI-experienced patients. These data support the use of low-dose ritonavir to enhance the level of exposure to amprenavir and increase the efficacy of amprenavir.
Population Pharmacokinetics and Pharmacodynamics of Efavirenz, Nelfinavir, and Indinavir: Adult AIDS Clinical Trial Group Study 398
Authors: Pfister Marc , Labbé Line , Hammer Scott M. , Mellors John , Bennett Kara K. , Rosenkranz Susan , Sheiner Lewis B. 
Published: December 2002

ABSTRACT

The present population pharmacokinetic (PK) and pharmacodynamic (PD) study modeled the effects of covariates including drug adherence and the coadministration of protease inhibitors (PIs) on the pharmacokinetics of efavirenz (EFV) and the relationship between EFV exposure and virological failure in patients who failed initial PI treatment in Adult AIDS Clinical Trial Group (AACTG) study 398. We also report on the population PKs of the PIs nelfinavir (NFV) and indinavir (IDV). AACTG study 398 patients received EFV, amprenavir, adefovir dipivoxil, and abacavir and were randomized to take, in addition, one of the following: NFV, IDV, saquinavir (SQV), or placebo. The PK databases consisted of 531 EFV concentrations (139 patients), 219 NFV concentrations (75 patients), and 66 IDV concentrations (11 patients). Time to virological failure was ascertained for all patients in the PK databases. PK data were fit with a population PK model that assumed exclusive hepatic elimination (the well-stirred model). Notable findings with respect to EFV PK and PD are as follows. (i) The hepatic clearance of EFV is unaltered by NFV, IDV, or SQV coadministration. (ii) The hepatic clearance of EFV appears to be 28% higher in white non-Hispanics than in African Americans and Hispanics (
P
= 0.03). (iii) Higher adherence scores (as measured with the Medication Event Monitoring System) are associated with marginally increased levels of exposure to EFV. (iv) In patients with no prior experience with nonnucleoside reverse transcriptase inhibitors (NNRTIs), a given percent increase in the oral clearance (CL/
F
) of EFV is associated with a greater percent increase in the hazard of virological failure (
P
< 0.0003). Among NNRTI-experienced patients, however, hazard is relatively uncorrelated with EFV CL/
F
.
Modeling of Transfer Kinetics at the Serum-Cerebrospinal Fluid Barrier in Rabbits with Experimental Meningitis: Application to Grepafloxacin
Authors: Pfister Marc , Zhang Liping , Hammarlund-Udenaes Margareta , Sheiner Lewis B. , Gerber Cynthia M. , Täuber Martin G. , Cottagnoud Philippe 
Published: December 2002

ABSTRACT

The goals of the present study were to model the population kinetics of in vivo influx and efflux processes of grepafloxacin at the serum-cerebrospinal fluid (CSF) barrier and to propose a simulation-based approach to optimize the design of dose-finding trials in the meningitis rabbit model. Twenty-nine rabbits with pneumococcal meningitis receiving grepafloxacin at 15 mg/kg of body weight (intravenous administration at 0 h), 30 mg/kg (at 0 h), or 50 mg/kg twice (at 0 and 4 h) were studied. A three-compartment population pharmacokinetic model was fit to the data with the program NONMEM (Nonlinear Mixed Effects Modeling). Passive diffusion clearance (CL
diff
) and active efflux clearance (CL
active
) are transfer kinetic modeling parameters. Influx clearance is assumed to be equal to CL
diff
, and efflux clearance is the sum of CL
diff
, CL
active
, and bulk flow clearance (CL
bulk
). The average influx clearance for the population was 0.0055 ml/min (interindividual variability, 17%). Passive diffusion clearance was greater in rabbits receiving grepafloxacin at 15 mg/kg than in those treated with higher doses (0.0088 versus 0.0034 ml/min). Assuming a CL
bulk
of 0.01 ml/min, CL
active
was estimated to be 0.017 ml/min (11%), and clearance by total efflux was estimated to be 0.032 ml/min. The population kinetic model allows not only to quantify in vivo efflux and influx mechanisms at the serum-CSF barrier but also to analyze the effects of different dose regimens on transfer kinetic parameters in the rabbit meningitis model. The modeling-based approach also provides a tool for the simulation and prediction of various outcomes in which researchers might be interested, which is of great potential in designing dose-finding trials.
Integration of a Transposon Tn
1
-Encoded Inhibitor-Resistant β-Lactamase Gene,
bla
TEM-67
from
Proteus mirabilis
, into the
Escherichia coli
Chromosome
Authors: Naas Thierry , Zerbib Marie , Girlich Delphine , Nordmann Patrice 
Published: December 2002

ABSTRACT

Proteus mirabilis
NEL-1 was isolated from a urine sample of a patient hospitalized in a long-term care facility. Strain NEL-1 produced a β-lactamase with a pI of 5.2 conferring resistance to amoxicillin and amoxicillin-clavulanic acid. Sequencing of a PCR amplicon by using TEM-specific primers revealed a novel
bla
TEM
gene,
bla
TEM-67
. TEM-67 was an IRT-1-like TEM derivative related to TEM-65 (Lys39, Cys244) with an additional Leu21Ile amino acid substitution in the leader peptide. The biochemical properties of TEM-67 were equivalent to those described for TEM-65. Analysis of sequences surrounding
bla
TEM-67
revealed that it was located on a transposon, Tn
1
, which itself was located on a 48-kb non-self-transferable plasmid, pANG-1. Electroporation of plasmid pANG-1 into
Escherichia coli
DH10B resulted in the integration of
bla
TEM-67
into the chromosome, whereas it remained episomal in the
P. mirabilis
CIP103181 reference strain. Further characterization of pANG-1 revealed the presence of two identical sequences on both sides of Tn
1
that contained an IS
26
insertion sequence followed by a novel colicin gene,
colZ
, which had 20% amino acid identity with other colicin genes. The characterization of this novel TEM derivative provides further evidence for the large diversity of plasmid-encoded β-lactamases produced in
P. mirabilis
and for their spread to other enterobacterial species through transposable-element-mediated events.
A Clonal Lineage of VanA-Type
Enterococcus faecalis
Predominates in Vancomycin-Resistant Enterococci Isolated in New Zealand
Authors: Manson Janet M. , Keis Stefanie , Smith John M. B. , Cook Gregory M. 
Published: December 2002

ABSTRACT

Avoparcin was used as a feed additive in New Zealand broiler production from 1977 until June 2000. We report here on the effects of the usage and discontinuation of avoparcin on the prevalence of vancomycin-resistant enterococci (VRE) in broilers. Eighty-two VRE isolates were recovered from poultry fecal samples between 2000 and mid-2001. VRE isolates were only obtained from broiler farms that were using, or had previously used, avoparcin as a dietary supplement. Of these VRE isolates, 73 (89%) were VanA-type
Enterococcus faecalis
and nine (11%) were VanA-type
Enterococcus faecium
. All
E. faecalis
isolates were found to have an identical or closely related pulsed-field gel electrophoresis (PFGE) pattern of
Sma
I-digested DNA and were susceptible to both ampicillin and gentamicin. The PFGE patterns of the nine
E. faecium
isolates were heterogeneous. All VRE contained both the
vanA
and
ermB
genes, which, regardless of species or PFGE pattern, resided on the same plasmid. Eighty-seven percent of the VRE isolates also harbored the
tet
(M) gene, while for 63 and 100%, respectively, of these isolates, the avilamycin and bacitracin MICs were high (≥256 μg/ml). Five of eight vancomycin-resistant
E. faecalis
isolates recovered from humans in New Zealand revealed a PFGE pattern identical or closely related to that of the
E. faecalis
poultry VRE isolates. Molecular characterization of Tn
1546
-like elements from the VRE showed that identical transposons were present in isolates from poultry and humans. Based on the findings presented here, a clonal lineage of VanA-type
E. faecalis
dominates in VRE isolated from poultry and humans in New Zealand.