bluuebunny/crossref_metadata_2025_split huggingface dataset:
Salicylic Acid and Ethylene Pathways Are Differentially Activated in Melon Cotyledons by Active or Heat-Denatured Cellulase fromTrichoderma longibrachiatum
Authors: Martinez Christelle , Blanc Frédéric , Le Claire Emilie , Besnard Olivier , Nicole Michel , Baccou Jean-Claude 
Published: July 2002

Abstract
Infiltration of cellulase (EC 3.2.1.4) from Trichoderma longibrachiatum into melon (Cucumis melo) cotyledons induced several key defense mechanisms and hypersensitive reaction-like symptoms. An oxidative burst was observed 3 hours after treatment and was followed by activation of ethylene and salicylic acid (SA) signaling pathways leading to marked induction of peroxidase and chitinase activities. The treatment of cotyledons by heat-denatured cellulase also led to some induction of peroxidase and chitinase activities, but the oxidative burst and SA production were not observed. Co-infiltration of aminoethoxyvinil-glycine (an ethylene inhibitor) with the active cellulase did not affect the high increase of peroxidase and chitinase activities. In contrast, co-infiltration of aminoethoxyvinil-glycine with the denatured enzyme blocked peroxidase and chitinase activities. Our data suggest that the SA pathway (induced by the cellulase activity) and ethylene pathway (induced by heat-denatured and active protein) together coordinate the activation of defense mechanisms. We found a partial interaction between both signaling pathways since SA caused an inhibition of the ethylene production and a decrease in peroxidase activity when co-infiltrated with denatured cellulase. Treatments with active or denatured cellulase caused a reduction in powdery mildew (Sphaerotheca fuliginea) disease.
High and low oxygen affinity conformations of T state hemoglobin
Authors: Bruno Stefano , Bonaccio Maria , Bettati Stefano , Rivetti Claudio , Viappiani Cristiano , Abbruzzetti Stefania , Mozzarelli Andrea 
Published: July 2002

AbstractTo understand the interplay between tertiary and quaternary transitions associated with hemoglobin function and regulation, oxygen binding curves were obtained for hemoglobin A fixed in the T quaternary state by encapsulation in wet porous silica gels. At pH 7.0 and 15°C, the oxygen pressure at half saturation (p50) was measured to be 12.4 ± 0.2 and 139 ± 4 torr for hemoglobin gels prepared in the absence and presence of the strong allosteric effectors inositol hexaphosphate and bezafibrate, respectively. Both values are in excellent agreement with those found for the binding of the first oxygen to hemoglobin in solution under similar experimental conditions. The corresponding Hill coefficients of hemoglobin gels were 0.94 ± 0.02 and 0.93 ± 0.03, indicating, in the frame of the Monod, Wyman, and Changeux model, that high and low oxygen‐affinity tertiary T‐state conformations have been isolated in a pure form. The values, slightly lower than unity, reflect the different oxygen affinity of α‐ and β‐hemes. Significantly, hemoglobin encapsulated in the presence of the weak effector phosphate led to gels that show intermediate oxygen affinity and Hill coefficients of 0.7 to 0.8. The heterogeneous oxygen binding results from the presence of a mixture of the high and low oxygen‐affinity T states. The Bohr effect was measured for hemoglobin gels containing the pure conformations and found to be more pronounced for the high‐affinity T state and almost absent for the low‐affinity T state. These findings indicate that the functional properties of the T quaternary state result from the contribution of two distinct, interconverting conformations, characterized by a 10‐fold difference in oxygen affinity and a different extent of tertiary Bohr effect. The very small degree of T‐state cooperativity observed in solution and in the crystalline state might arise from a ligand‐induced perturbation of the distribution between the high‐ and low‐affinity T‐state conformations.
Total chemical synthesis of human matrix Gla protein
Authors: Hackeng Tilman M. , Rosing Jan , Spronk Henri M.H. , Vermeer Cees 
Published: July 2002

AbstractHuman matrix Gla protein (MGP) is a vitamin K–dependent extracellular matrix protein that binds Ca2+ ions and that is involved in the prevention of vascular calcification. MGP is a 10.6‐kD protein (84 amino acids) containing five γ‐carboxyglutamic acid (Gla) residues and one disulfide bond. Studies of the mechanism by which MGP prevents calcification of the arterial media are hampered by the low solubility of the protein (<10 μg/mL). Because of solubility problems, processing of a recombinantly expressed MGP‐fusion protein chimera to obtain MGP was unsuccessful. Here we describe the total chemical synthesis of MGP by tBoc solid‐phase peptide synthesis (SPPS) and native chemical ligation. Peptide Tyr1‐Ala53 was synthesized on a derivatized resin yielding a C‐terminal thioester group. Peptide Cys54‐Lys84 was synthesized on Lys‐PAM resin yielding a C‐terminal carboxylic acid. Subsequent native chemical ligation of the two peptides resulted in the formation of a native peptide bond between Ala53 and Cys54. Folding of the 1–84‐polypeptide chain in 3 M guanidine (pH 8) resulted in a decrease of molecular mass from 10,605 to 10,603 (ESI‐MS), representing the loss of two protons because of the formation of the Cys54‐Cys60 internal disulfide bond. Like native MGP, synthetic MGP had the same low solubility when brought into aqueous buffer solutions with physiological salt concentrations, confirming its native like structure. However, the solubility of MGP markedly increased in borate buffer at pH 7.4 in the absence of sodium chloride. Ca2+‐binding to MGP was confirmed by analytical HPLC, on which the retention time of MGP was reduced in the presence of CaCl2. Circular dichroism studies revealed a sharp increase in α‐helicity at 0.2 mM CaCl2 that may explain the Ca2+‐dependent shift in high‐pressure liquid chromatography (HPLC)‐retention time of MGP. In conclusion, facile and efficient chemical synthesis in combination with native chemical ligation yielded MGP preparations that can aid in unraveling the mechanism by which MGP prevents vascular calcification.
Coupled deformation-diffusion effects in the mechanics of faulting
and failure of geomaterials
Authors: Rudnicki JW 
Published: July 2002

Abstract
This review article discusses the applications of poroelasticity to the mechanics of faulting and failure in geomaterials. Values of material parameters inferred from laboratory and field studies are summarized. Attention is focused on solutions for shear dislocations and shear cracks. A common feature is that undrained response, invoked by rapid slip or deformation, is stiffer than drained response, which occurs for slower slip or deformation. The time and spatial variation of the stress and pore pressure is different for slip on permeable and impermeable planes. These solutions are applied to interpretation of water well level changes due to slip, earthquake precursory processes, and stabilization of spreading slip zones. Inclusion models for reservoirs, aquifers, and other inhomogeneities are formulated and the results are applied to stress and strain changes caused by fluid mass injection or withdrawal.
A New Device for Measuring the Viscoelastic Properties of Hydrated Matrix Gels
Authors: Parsons Jeffrey W. , Coger Robin N. 
Published: July 2002

AbstractDeterminations of the viscoelastic properties of extracellular matrices (ECMs) are becoming increasingly important for accurate predictive modeling of biological systems. Since the interactions of the cells with the ECM and surrounding fluid (e.g., blood, media) each affect cell behavior; it is advantageous to evaluate the ECM’s material properties in the presence of the hydrating fluid. Conventional rheometry methods evaluate the bulk material properties of gel materials while displacing the hydrating liquid film. Such systems are therefore nonideal for testing materials such as ECMs, whose properties change with dehydration. The new, patent pending, piezoelectrically actuated linear rheometer is designed to eliminate this problem. It uses a single cantilever to apply an oscillating load to the gel and to sense the gel’s deflection. Composed of two thin film piezopolymer layers, the cantilever uses one layer as the actuator, and the second piezopolymer layer to measure the lateral movement of its attached probe. The viscoelastic nature of the ECM adds stiffness and damping to the system, resulting in the attenuation and phase shift of the sensor’s output voltage. From these parameters, the ECM’s shear storage and loss moduli are then determined. Initial tests on the BioMatrix I and type I collagen ECMs reveal that the first prototype of the piezoelectrically actuated linear rheometer is capable of accurately determining the trend and order of magnitude of an ECM’s viscoelastic properties. In this paper, details of the rheometer’s design and operating principles are described.
A Dynamical Systems Approach to Damage Evolution Tracking, Part 1: Description and Experimental Application
Authors: Chelidze David , Cusumano Joseph P. , Chatterjee Anindya 
Published: July 2002

AbstractIn this two-part paper we present a novel method for tracking a slowly evolving hidden damage process responsible for nonstationarity in a fast dynamical system. The development of the method and its application to an electromechanical experiment is the core of Part 1. In Part 2, a mathematical model of the experimental system is developed and used to validate the experimental results. In addition, an analytical connection is established between the tracking method and the physics of the system based on the idea of averaging and the slow flow equations for the hidden process. The tracking method developed in this study uses a nonlinear, two-time-scale modeling strategy based on the delay reconstruction of a system’s phase space. The method treats damage-induced nonstationarity as evolving in a hierarchical dynamical system containing a fast, directly observable subsystem coupled to a slow, hidden subsystem. The utility of the method is demonstrated by tracking battery discharge in a vibrating beam system with a battery-powered electromagnetic restoring force. Applications to systems with evolving material damage are also discussed.
Falling Film Transitions on Plain and Enhanced Tubes
Authors: Roques J. F. , Dupont V. , Thome J. R. 
Published: July 2002

Abstract
In falling film heat transfer on horizontal tube bundles, liquid flow from tube to tube occurs as a falling jet that can take on different flow modes. At low flow rates, the liquid film falls as discrete droplets. At higher flow rates, these droplets form discretely spaced liquid columns. At still higher flow rates, the film falls as a continuous sheet of liquid. Predicting the flow transitions between these flow modes is an essential step in determining the heat transfer coefficient for the particular flow mode, whether for a single phase process or for falling film condensation or evaporation. Previous studies have centered mostly on falling films on plain tube arrays. The objective of the present study is to extend the investigation to tubes with enhanced surfaces: a low finned tube, an enhanced boiling tube and an enhanced condensation tube. The effect of tube spacing on flow transition has also been investigated. The test fluids were water, glycol and a glycol-water mixture. The adiabatic experimental results show that the flow mode transition thresholds for the enhanced boiling tube are very similar to those of the plain tube while the fin structure of the other two enhanced tubes can significantly shift their transition thresholds.
Ship Capsize Risk in a Seaway Using Fitted Distributions to Roll
Maxima
Authors: McTaggart Kevin A. 
Published: July 2002

Abstract
This paper presents an efficient method for determining capsize risk for a given seaway and ship operational condition using time domain simulations. The risk of capsize during 1 h exposure to a given seaway is dependent on the wave process realization, which is determined by a seed number and resulting random wave phases. The dependence of maximum roll angle on wave process can be modeled by fitting a suitable distribution to maximum roll angles from a moderate number of simulations. Sample computations for a naval frigate demonstrate that a Gumbel distribution provides a very good fit to maximum roll angles from different wave realizations. [S0892-7219(00)00402-7]
Science in Japan: Competition on Campus
Authors: Mervis Jeffrey 
Published: July 2002

Two opposing forces--competition and cooperation--are beginning to coexist at Japanese universities as they enter an era of increased funding, increased demand for graduate students, and increased pressure to contribute to the country's economic growth. The new environment promises to be a challenging one, with great rewards for those who succeed and great risks for those who fail to keep pace.
On the competitive side, there is the unprecedented bidding for talented students, the growing use of peer review to make awards, and the emerging recognition that lifetime tenure, tiny but equitable grants, and immobility are not compatible with cutting-edge science. Those below the top tier--dominated by the University of Tokyo and Kyoto University--liken the new atmosphere to the law of the jungle: "I have to get everything for my team by myself, like a small yakuza [organized crime] boss," says one researcher at Waseda University.
But cooperation is too deeply ingrained in Japanese culture to be driven out by the latest demands on science. From high school teachers sharing their ideas on improving the precollege science curriculum to universities putting out the welcome mat for foreign scientists, increased domestic and international collaboration are seen as vital to a successful transformation of academic science.
The stories in this special section are intended to be a snapshot of life on campus and the issues affecting academic research in Japan. It is part of our broader, ongoing effort to report on the country's vibrant and growing scientific enterprise. We welcome your comments and your ideas for future coverage.
Jeffrey Mervis
Choice of Ph.D. or job
This section was reported and written by Dennis Normile, head of the Japan news bureau of Science, and June Kinoshita, a science writer based in Belmont, Massachusetts.

For more information on career opportunities, see Science's Next Wave's forum on “s
Training Young Scientists in Asia for the 21st Century
.”
Comparison of a New Triazole, Posaconazole, with Itraconazole and Amphotericin B for Treatment of Histoplasmosis following Pulmonary Challenge in Immunocompromised Mice
Authors: Connolly Patricia , Wheat L. Joseph , Schnizlein-Bick Carol , Durkin Michelle , Kohler Steve , Smedema Melinda , Goldberg Janet , Brizendine Edward , Loebenberg David 
Published: July 2002

ABSTRACTA murine model of intratracheally induced histoplasmosis in immunocompromised B6C3F1mice was used to evaluate a new triazole antifungal agent, posaconazole. This compound was previously shown to be comparable to amphotericin B and superior to itraconazole for the treatment of histoplasmosis in immunocompetent mice. The current study used mice that were depleted of T lymphocytes by intraperitoneal injection of anti-CD4 and anti-CD8 monoclonal antibodies beginning 2 days before infection and continuing at 5-day intervals until completion of the study. Groups of B6C3F1mice that were depleted of CD4 and CD8 T cells were infected with an inoculum of 104Histoplasma capsulatumyeasts. All mice receiving posaconazole at 1 or 0.1 mg/kg of body weight/day, amphotericin B at 2 mg/kg every other day (qod), or itraconazole at 75 mg/kg/day survived to day 29. Only 60% of mice receiving itraconazole at 10 mg/kg/day and none receiving amphotericin B at 0.2 mg/kg qod survived to that date. Fungal burdens were determined at day 14 of infection, 1 day after discontinuation of therapy. Quantitative colony counts andHistoplasmaantigen levels in lung and spleen tissues declined following treatment with amphotericin B at 2 mg/kg qod, posaconazole at 5 and 1 mg/kg/day, and itraconazole at 75 mg/kg/day but not in mice treated with amphotericin B at 0.2 mg/kg qod or itraconazole at 10 mg/kg/day. Posaconazole at 0.1 mg/kg/day reduced fungal colony counts and antigen levels in spleens but not in lungs. This study shows posaconazole activity for the treatment of histoplasmosis in immunosuppressed animals.
Detection of Florfenicol Resistance Genes inEscherichia coliIsolated from Sick Chickens
Authors: Keyes Kathleen , Hudson Charlene , Maurer John J. , Thayer Stephan , White David G. , Lee Margie D. 
Published: July 2002

ABSTRACTFlorfenicol is an antibiotic approved for veterinary use in cattle in the United States in 1996. Although this drug is not used in poultry, we have detected resistance to florfenicol in clinical isolates of avianEscherichia coli. Molecular typing demonstrated that the florfenicol resistance gene,flo, was independently acquired and is plasmid encoded.
Efficacy of FK463, a New Lipopeptide Antifungal Agent, in Mouse Models of Disseminated Candidiasis and Aspergillosis
Authors: Ikeda Fumiaki , Wakai Yoshimi , Matsumoto Satoru , Maki Katsuyuki , Watabe Etsuko , Tawara Shuichi , Goto Toshio , Watanabe Yuji , Matsumoto Fumio , Kuwahara Shogo 
Published: July 2002

ABSTRACT

The efficacy of intravenous injection of FK463, a novel water-soluble lipopeptide, was evaluated in mouse models of disseminated candidiasis and aspergillosis and was compared with those of fluconazole (FLCZ) and amphotericin B (AMPH-B). In the candidiasis model, FK463 significantly prolonged the survival of intravenously infected mice at doses of 0.125 mg/kg of body weight or higher. In disseminated candidiasis caused by
Candida
species, including FLCZ-resistant
Candida albicans
, FK463 exhibited an efficacy 1.4 to 18 times inferior to that of AMPH-B, with 50% effective doses (ED
50
s) ranging from 0.21 to 1.00 mg/kg and 0.06 to 0.26 mg/kg, respectively, and was much more active than FLCZ. The protective effect of FK463 was not obviously influenced by the fungal inoculum size, the starting time of the treatment, or the immunosuppressed status of the host. The reduction in efficacy was less than that observed with FLCZ or AMPH-B. The efficacy of FK463 was also evaluated in the disseminated candidiasis target organ assay and was compared with those of FLCZ and AMPH-B. Efficacies were evaluated on the basis of a comparison between the mean log
10
CFU in kidneys in the groups treated with antifungal agents and that in control group. A single dose of FK463 at 0.5 mg/kg or higher significantly reduced the viable counts in kidneys compared with the numbers of yeast cells before treatment, and its efficacy was comparable to that of AMPH-B, while FLCZ at 4 mg/kg showed only a suppressive effect on the growth of
C. albicans
in the kidneys. In the disseminated aspergillosis model, FK463 given at doses of 0.5 mg/kg or higher significantly prolonged the survival of mice infected intravenously with
Aspergillus fumigatus
conidia. The efficacy of FK463 was about 2 times inferior to that of AMPH-B, with ED
50
s ranging from 0.25 to 0.50 mg/kg and 0.11 to 0.29 mg/kg, respectively. These results indicate that FK463 may be a potent parenterally administered therapeutic agent for disseminated candidiasis and aspergillosis.
In Vitro Activities of Nontraditional Antimicrobials against Multiresistant
Acinetobacter baumannii
Strains Isolated in an Intensive Care Unit Outbreak
Authors: Appleman Maria D. , Belzberg Howard , Citron Diane M. , Heseltine Peter N. R. , Yellin Albert E. , Murray James , Berne Thomas V. 
Published: July 2002

ABSTRACT

Fifteen multiresistant
Acinetobacter baumannii
isolates from patients in intensive care units and 14 nonoutbreak strains were tested to determine in vitro activities of nontraditional antimicrobials, including cefepime, meropenem, netilmicin, azithromycin, doxycycline, rifampin, sulbactam, and trovafloxacin. The latter five drugs were further tested against four of the strains for bactericidal or bacteriostatic activity by performing kill-curve studies at 0.5, 1, 2, and 4 times their MICs. In addition, novel combinations of drugs with sulbactam were examined for synergistic interactions by using a checkerboard configuration. MICs at which 90% of the isolates tested were inhibited for antimicrobials showing activity against the multiresistant
A. baumannii
strains were as follows (in parentheses): doxycycline (1 μg/ml), azithromycin (4 μg/ml), netilmicin (1 μg/ml), rifampin (8 μg/ml), polymyxin (0.8 U/ml), meropenem (4 μg/ml), trovafloxacin (4 μg/ml), and sulbactam (8 μg/ml). In the kill-curve studies, azithromycin and rifampin were rapidly bactericidal while sulbactam was more slowly bactericidal. Trovafloxacin and doxycycline were bacteriostatic. None of the antimicrobials tested were bactericidal against all strains tested. The synergy studies demonstrated that the combinations of sulbactam with azithromycin, rifampin, doxycycline, or trovafloxacin were generally additive or indifferent.
Control of Staphylococcal Adhesion to Polymethylmethacrylate and Enhancement of Susceptibility to Antibiotics by Poloxamer 407
Authors: Veyries Marie-Laure , Faurisson Francois , Joly-Guillou Marie-Laure , Rouveix Bernard 
Published: July 2002

ABSTRACT
We studied the antiadhesive effect of Poloxamer 407 (P407), together with modifications in the antimicrobial susceptibility of residual adherent staphylococci. Bacterial adherence was markedly inhibited (77% to more than 99.9%) whether polymethylmethacrylate was exposed to P407 before or during the adherence assay. Furthermore, residual adherent staphylococci appeared to be more susceptible to antibiotic activity, suggesting that combination of P407 with antibiotics could be a promising approach to the prevention of infection of foreign material.
Contributions of the AmpC β-Lactamase and the AcrAB Multidrug Efflux System in Intrinsic Resistance of
Escherichia coli
K-12 to β-Lactams
Authors: Mazzariol Annarita , Cornaglia Giuseppe , Nikaido Hiroshi 
Published: July 2002

ABSTRACT

The roles of the AmpC chromosomal β-lactamase and the AcrAB efflux system in levels of intrinsic resistance and susceptibility of
Escherichia coli
to β-lactams were studied with a set of isogenic strains. MICs of ureidopenicillins, carbenicillin, oxacillin, and cloxacillin were drastically reduced by the inactivation of AcrAB, whereas those of the earlier cephalosporins were affected mostly by the loss of AmpC β-lactamase.