bluuebunny/crossref_metadata_2025_split huggingface dataset:
Inhibitor-Sensitive AmpC β-Lactamase Variant Produced by an
Escherichia coli
Clinical Isolate Resistant to Oxyiminocephalosporins and Cephamycins
Authors: Doi Yohei , Wachino Jun-ichi , Ishiguro Masaji , Kurokawa Hiroshi , Yamane Kunikazu , Shibata Naohiro , Shibayama Keigo , Yokoyama Keiko , Kato Haru , Yagi Tetsuya , Arakawa Yoshichika 
Published: June 2004

ABSTRACT

Escherichia coli
HKY28, a ceftazidime-resistant strain isolated from a urine specimen in Japan, produced an inhibitor-sensitive AmpC β-lactamase variant. The deduced amino acid sequence of the enzyme contained a number of substitutions and a tripeptide deletion (Gly286-Ser287-Asp288) compared with the sequence of native AmpC of
E. coli
. When the deletion was reverted by a 9-base insertion at the relevant site of
ampC
in the clone, the typical inhibitor-resistant phenotype of AmpC was restored, while at the same time the levels of resistance to ceftazidime, cefpirome, and cefepime were reduced eightfold or more. Molecular modeling studies indicated that a structural change took place in the H-10 helix as a result of the deletion, and this change caused an alteration of the substrate binding site, leading to a unique phenotype analogous to that of inhibitor-sensitive class A extended-spectrum β-lactamases. The degree of inhibition was greater with sulbactam and tazobactam than with clavulanic acid. To our knowledge, this is the first report to have characterized an
E. coli ampC
that encodes chromosomal AmpC β-lactamase sensitive to the available β-lactamase inhibitors.
Oxygen Limitation Contributes to Antibiotic Tolerance of
Pseudomonas aeruginosa
in Biofilms
Authors: Borriello Giorgia , Werner Erin , Roe Frank , Kim Aana M. , Ehrlich Garth D. , Stewart Philip S. 
Published: June 2004

ABSTRACT

The role of oxygen limitation in protecting
Pseudomonas aeruginosa
strains growing in biofilms from killing by antibiotics was investigated in vitro. Bacteria in mature (48-h-old) colony biofilms were poorly killed when they were exposed to tobramycin, ciprofloxacin, carbenicillin, ceftazidime, chloramphenicol, or tetracycline for 12 h. It was shown with oxygen microelectrodes that these biofilms contain large anoxic regions. Oxygen penetrated about 50 μm into the biofilms, which averaged 210 μm thick. The region of active protein synthesis was visualized by using an inducible green fluorescent protein. This zone was also limited to a narrow band , approximately 30 μm wide, adjacent to the air interface of the biofilm. The bacteria in mature biofilms exhibited a specific growth rate of only 0.02 h
−1
. These results show that 48-h-old colony biofilms are physiologically heterogeneous and that most of the cells in the biofilm occupy an oxygen-limited, stationary-phase state. In contrast, bacteria in 4-h-old colony biofilms were still growing, active, and susceptible to antibiotics when they were challenged in air. When 4-h-old colony biofilms were challenged under anaerobic conditions, the level of killing by antibiotics was reduced compared to that for the controls grown aerobically. Oxygen limitation could explain 70% or more of the protection afforded to 48-h-old colony biofilms for all antibiotics tested. Nitrate amendment stimulated the growth of untreated control
P. aeruginosa
isolates grown under anaerobic conditions but decreased the susceptibilities of the organisms to antibiotics. Local oxygen limitation and the presence of nitrate may contribute to the reduced susceptibilities of
P. aeruginosa
biofilms causing infections in vivo.
Active Efflux of Ciprofloxacin from J774 Macrophages through an MRP-Like Transporter
Authors: Michot Jean-Michel , Van Bambeke Françoise , Mingeot-Leclercq Marie-Paule , Tulkens Paul M. 
Published: June 2004

ABSTRACT
The accumulation and efflux kinetics of ciprofloxacin have been examined by using murine J774 macrophages. Accumulation (at equilibrium) was increased (three- to fourfold) (i) when cells were incubated with high extracellular drug concentrations (typically 200 mg/liter) as opposed to clinically meaningful concentrations (10 mg/liter or lower), (ii) during ATP- depletion and at acid pH, and (iii) during coincubation with probenecid, gemfibrozil and the preferential multidrug resistance-related protein (MRP) inhibitor MK571. All these conditions were also associated with a marked decrease in ciprofloxacin efflux (half-lives increased from <2 min in controls to up to 10 min). Monensin (a proton ionophore), verapamil, and the preferential P-glycoprotein (P-gp) inhibitor GF120918 had no or only minimal effect, while cyclosporin A, which is not specific for P-gp but also acts on MRP, had an intermediate effect. Short-term uptake studies showed that the influence of the modulators on the apparent drug influx was almost immediate (delay of ≤1 min). Cells made resistant to probenecid and showing a marked overexpression of MRP1 (by Western blot analysis and confocal microscopy) accumulated ciprofloxacin to almost the same extent as did control cells, but efflux was inhibited less by probenecid, gemfibrozil, and MK571. We conclude that ciprofloxacin is subject to constitutive efflux in J774 macrophages through the activity of an MRP-related transporter which is probably distinct from MRP1. We also suggest that the cellular accumulation of ciprofloxacin in wild-type cells is constitutively impaired at therapeutically meaningful concentrations.
Purification and Characterization of Recombinant
Staphylococcus haemolyticus
DNA Gyrase and Topoisomerase IV Expressed in
Escherichia coli
Authors: Bronstein Joel C. , Olson Stacey L. , LeVier Kristin , Tomilo Mark , Weber Peter C. 
Published: June 2004

ABSTRACT

The subunits of DNA gyrase and topoisomerase IV from
Staphylococcus haemolyticus
were expressed in
Escherichia coli
, purified to homogeneity, and used to reconstitute active enzymes that were sensitive to known topoisomerase inhibitors. This represents the first description of a method for isolating type II topoisomerases of a coagulase-negative staphylococcal species.
Function and survival of dendritic cells depend on endothelin-1 and endothelin receptor autocrine loops
Authors: Guruli Georgi , Pflug Beth R. , Pecher Stefana , Makarenkova Valeria , Shurin Michael R. , Nelson Joel B. 
Published: June 2004

AbstractThe biologic effects of endothelin-1 (ET-1) are not limited to its potent vasoconstricting activity. The endothelin receptors, ETA and ETB, have differential tissue and functional distributions. Here we showed that dendritic cells (DCs), the major antigen-presenting cells in the adaptive limb of the immune system, produce large amounts of ET-1 and significantly increase the expression of endothelin receptors upon maturation. Selective blockade of the ETA receptor significantly reduced expression of the mature DC marker CD83, decreased the production of the immunostimulatory cytokine interleukin-12, down-regulated DC ability to stimulate T cells, and promoted DC apoptosis. Selective ETB receptor blockade, on the other hand, resulted in increased expression of CD83 and improved DC survival. Therefore, ET-1/ETA/ETB autocrine/paracrine loops on DCs appear to be essential for the normal maturation and function of human DCs, presenting a unique target for immunomodulatory therapies. (Blood. 2004;104:2107-2115)
A new anti-idiotype antibody capable of binding rituximab on the surface of lymphoma cells
Authors: Cragg Mark S. , Bayne Mike B. , Tutt Alison L. , French Ruth R. , Beers Stephen , Glennie Martin J. , Illidge Timothy M. 
Published: June 2004

AbstractThe chimeric anti-CD20 monoclonal antibody (mAb), rituximab, is an established part of the management of many non-Hodgkin lymphomas. The in vivo action of rituximab remains elusive, and this partially reflects a lack of highly specific reagents to detect rituximab binding at the cell surface. Here we report a new high-affinity mAb (MB2A4) with fine specificity for the idiotype of rituximab. It is able to detect rituximab in vitro, in the presence of high levels of human immunoglobulin G (IgG), in the serum of patients receiving rituximab therapy, and, surprisingly, when rituximab is bound to CD20 on the cell surface. We propose that the anti–idiotype (Id) binds to rituximab molecules bound univalently at the cell surface, facilitated by the relatively high off-rate of rituximab. This reagent provides new insights into the binding of rituximab at the cell surface and demonstrates a mode of binding that could be exploited for the surface detection of other mAbs with clinical and biologic applications.
Agentensysteme für die Logistik im Schienenverkehr (Multi Agent Systems for Logistics in Rail Transport)
Authors: Braun Imma , König Stefan , Schnieder Eckehard 
Published: June 2004

Abstract
Der makrologistische Strukturwandel des Güterverkehrsmarkts, hervorgerufen durch Substitutions-, Güterstruktur-, Logistik- und Integrationseffekte, führt infolge veränderter Anforderungen an die Strukturen und Prozesse des Güterverkehrs zu zunehmenden Verlusten an Marktanteilen des Schienengüterverkehrs am Gesamtgüterverkehrsmarkt. Ursache hierfür ist eine mangelnde Übereinstimmung von gewandelten Kundenanforderungen mit dem Leistungsangebot des Schienenverkehrs. Der Beitrag stellt ein neues Logistikkonzept für den Bahnbereich vor, das die Flexibilität im Schienengüterverkehr durch die Verschränkung von Organisations- und Betriebsprozessen erhöht. In Kombination mit dem Einsatz kleiner, autonomer Transporteinheiten trägt es dazu bei, den veränderten Marktanforderungen an den Güterverkehr gerecht zu werden.
Phase equilibria in systems with ethylene above its critical temperature
Authors: Todd David B. , Elgin Joseph C. 
Published: June 2004

AbstractA study was made of the mutual solubility of ethylene with various polar and nonpolar relatively high‐molecular‐weight organic compounds at temperatures 1° and 10° C. respectively above the critical temperature of ethylene and at pressures up to 1,500 Ib./sq.in.abs. For many compounds Henry's law was found to be applicable for the liquid phase up to approximately two thirds of the critical pressure of ethylene. In the critical region the solubility of ethylene was extremely sensitive to small changes in both temperature and pressure. The various types of phase behavior encountered were classified according to the nonideality involved. The results of this investigation indicate that a gas near its critical conditions is often capable of dissolving relatively nonvolatile materials in sufficient concentrations to warrant consideration of a separation process using such a gas as the extracting medium, namely fluid‐liquid extraction.
The fall of single liquid drops through water
Authors: Hu Shegen , Kinter R. C. 
Published: June 2004

AbstractThe steady motion of single drops of ten organic liquids falling through a stationary water field is discussed. A correlation is presented for nine systems with the exception of the aniline‐water system, in the form of a single curve relating the drag coefficient, Weber number, Reynolds number, and a physical property group. The curve can be used directly to predict the terminal velocity, drag coefficient, Reynolds number, and Weber number for any given equivalent drop size.A break point in the curve serves to predict the peak velocity and its related quantities. The critical drop size is predicted from the pertinent physical properties alone. All these estimations were accurate within 10% for the systems used. The interfacial tensions ranged from 24 to 45 dynes/cm. and the drop densities from 1.100 to 2.947g./ml., the latter resulting in a twentyfold range of density differences. The drop viscosities had no apparent effect.
Absorption of ethylene oxide in a packed column with various solvents
Authors: Bonilla C F. , Baron S. 
Published: June 2004

AbstractData were obtained on the solubility of ethylene oxide gas in a number of aqueous and nonaqueous solvents at various temperatures and gas concentrations. Its absorption from high concentrations in air was studied in a packed column with a cooling jacket for removal of the heat evolved. The results can be correlated with adequate accuracy in terms of the conditions at the top or dilute end of the column. The values of (H.T.U.)G and (H.T.U.)L agree approximately with known values for other systems. For the solvents tested, the liquid‐film resistance is controlling at room temperatures.
Transport of momentum and energy in a ducted jet: I. Experimental study of a nonisothermal jet of air discharging into a duct
Authors: Alexander L. G. , Kivnick Arnold , Comings E. W. , Henze E. D. 
Published: June 2004

AbstractA heated jet of air from an 0.898‐in. standard A.S.M.E. nozzle was discharged into a 4‐in. steel duct, well insulated over its entire 10‐ft. length. Air from the region surrounding the nozzle was entrained into the duct. At a number of points along the duct, radial profiles of air velocity and temperature were obtained by means of a probe which combined an impact tube and a thermocouple. The temperature at each of several points along the duct wall was indicated by thermocouples imbedded in the wall.In the experiments reported here the velocity at the jet was 585 ft./sec.; the temperature of the jet was about 220°F. and that of the entrained air was about 88°F. The total air flow rate through the duct was 0.67 lb./sec., and the heat flux was 4.9 B.t.u./sec., with the temperature of the entrained air taken as the datum.The radial and axial profiles of velocity and temperature are compared and discussed; the temperatures of the stream near the duct wall and of the duct wall itself are given. Conservation of mass and heat was checked by graphical integration of the radial profiles.
Use of the redlich and kwong equation of state in calculating thermodynamic properties of gases from experimental compressibility data
Authors: Van Ness Hendrick C. 
Published: June 2004

AbstractConvenient and accurate methods of calculating the thermodynamic properties of gases from experimental compressibility‐factor data through the use of the Redlich and Kwong equation of state are presented. Analytical and graphical methods are combined. As an example, fugacity and activity coefficients are calculated for the nitrogen‐ethylene system at 50°C. for pressures up to 500 atm.
Kinetics of the catalyzed and uncatalyzed liquid‐phase hydration of propylene oxide
Authors: Benham A. L. , Kurata Fred 
Published: June 2004

AbstractThe kinetics of the catalytic and noncatalytic hydration of propylene oxide were studied in a continuous reactor. Both the catalytic and noncatalytic reaction were studied over a temperature range of 100° to 300°F. The feed ratios ranged from 2.5 to 10 lb. water/lb. propylene oxide. In the case catalytic reaction, the catalyst concentration of sulfuric acid ranged up to 0.25 wt. % of the total feed.The study showed the noncatalytic reaction to be pseudo first order with respect to propylene oxide, and an equation was found for the rate constant. The catalytic reaction was found to be pseudo second order with respect to propylene oxide, and the effect of the catalyst concentration is shown graphically.
Critical constants of unsaturated aliphatic hydrocarbons
Authors: Thodos George 
Published: June 2004

AbstractThe van der Waals' constanta a andb evaluated from structural considerations of the unsaturated aliphatic hydrocarbons are used to calculate the critical constants for these types of compounds. For these unsaturated hydrocarbons, both van der Waals' constants are calculated through the additive contribution of unsaturated bonds to the van der Waals' constants of the corresponding saturated aliphatic hydrocarbons calculated according to a method previously proposed (6).With both van der Waals' constants available, the critical temperatures, pressures, and volumes for these types of compounds can be obtained.By use of this approach, the critical temperatures, pressures, and volumes of several olefins, diolefins, and acetylenes have been calculated. These calculated values have been compared whenever possible with values reported in the literature to produce an average percentage deviation of 1.3 for the critical temperature, 3.0 for the critical pressure, and 1.5 for the critical volume. In this comparison questionable literature values have been included, and consequently the reported deviations present the worst possible expectation.
Gas absorption in beds of rings and saddles
Authors: Leva Max 
Published: June 2004

AbstractNew data are presented for the system carbon dioxide—sodium hydroxide. The effect of CO3= build‐up upon KGa values was investigated first and the data were then used to construct a curve by means of which all data were corrected to an arbitrarily chosen reference state of 25% CO3= concentration. KGa values increased with increasing liquid rate but were not dependent on gas rate if the packings were operated below loading. For some packings examined in the loading range, however, KGa values increased with increasing gas rate.KGa values examined in relation to specific surface area were found to be very irregular in connection with rings. The surface‐area utilization pattern of the saddles was considerably more uniform. The ring and saddle data for the carbon dioxide‐sodium hydroxide system were in good qualitative agreement with the ammonia absorption data of Fellinger and the water‐water vapor data of Mehta and Parekh.
Total pressure method for vapor‐liquid equilibria at low absolute pressures: Aniline‐nitrobenzene systems
Authors: Holzlander G. W. , Riggle J. W. 
Published: June 2004

AbstractBinary vapor‐liquid equilibrium data for use in the successful design and operation of mass transfer equipment at pressures down to approximately 5 mm. Hg may be advantageously obtained by the method of total pressures. In this method the desired equilibrium data are derived from pressure vs. temperature measurements on a convnient number of made‐up solutions covering the entire composition range.With a modified Smith and Menzies isoteniscope, it is possible to measure accurately the data required for making the equilibrium calculations down to 2 mm. abs. pressure without the “bumping,” supercooling, and superheating encountered with equilibrium stills. The isoteniscope is simple to construct and operate from 1 atm. to 2 mm. abs.The use of the total pressure method and the isoteniscope is illustrated by the determination of the vapor‐liquid equilibrium in the aniline‐nitrobenzene system at 5 and 10 mm. abs. In nineteen out of twenty instances the vapor compositions for a given liquid composition are precise to within ± 0.9% and the relative volatility, which varied between 2.54 and 1.85 over the composition and temperature ranges, is precise within ± 1.5%.
Effect of drying conditions on drying rate and physical properties of a porous solid
Authors: Lebeis E. H. , Burtis T. A. 
Published: June 2004

AbstractRate data are presented for both the constant ‐ and the falling‐rate drying of closely sized spheres of silica‐alumina hydrogel. This hydrogel, which contains a fine powder, is the starting material from which petroleum cracking catalysts may be prepared. During the constant‐rate period the drying rate is directly proportional to the difference between the dry‐ and wet‐bulb temperatures of the air. In the falling‐rate period the rate is proportional to the free water content, the proportionality factor being an undetermined function of the dry‐bulb‐wet‐bulb differential.Drying severity during the falling‐rate period is shown to be the major determinant of the final pellet density. At constant wet‐bulb temperature, density is inversely related to the dry‐bulb‐wet‐bulb differential. If this differential is held constant, density is directly related to the wet‐bulb temperature.The variation in drying rate with position in the bed for through‐circulation constant‐rate drying of deep beds of particles is analyzed for the case where the direction of air flow is periodically reversed for equal time intervals. It is indicated that uniformity of drying should increase with an increase in air velocity, but decrease as bed depth is increased. At constant conditions and bed depth, large particles should dry more uniformly than small. Within normal operating ranges, air temperature and humidity should have little effect on drying uniformity.
Analysis of gas‐fluidized solid systems by x‐ray absorption
Authors: Grohse E. W. 
Published: June 2004

AbstractX‐ray absorption is presented as a unique tool for the study of the fundamentals of gas fludization. For example, bed‐density profiles, valuable indexes of the quality of fluidization, are readily determined by means of X‐ray absorption. No internal probes, to interfere with the normal action within a fluidized bed, are involved.As an initial application of X‐ray absorption to fluidization, the results of a study of the effect of mode of distribution of gas to a fluidized bed are presented. The importance of this variable, only superficially discussed in previous literature, is clearly shown by these results. Application of X‐ray absorption to other chemical engineering operations is readily conceivable.
Mechanism of heat transfer to fluidized beds
Authors: Mickley H. S. , Fairbanks D. F. 
Published: June 2004

AbstractIn order to determine the nature of the resistance controlling heat transfer between fluidized beds and surfaces in contact with them, heat transfer measurements were made on the same solid constituents with several different fluidizing gases. The heat transfer coefficients obtained with fluidized beds are found to be proportional to the square root of the thermal conductivity of the quiescent beds. This result indicates that the process controlling fluidized heat transfer may be considered to be an unsteady‐state diffusion of heat into mobile elements of quiescent bed material.This picture is analyzed mathematically to yield an equation for the heat transfer coefficient h = h \documentclass{article}\pagestyle{empty}\begin{document}$ h = \sqrt {{\rm K}_{\rm m} \rho _{\rm m} cS} $\end{document} wherein the effects of the bed thermal properties are separated from the effects of the stirring factor S, which accounts for bed motion and geometry. The mass transfer analogue is also derived and shown to correlate existing mass and heat transfer data reasonably well.It is concluded that the proposed mechanism yields a satisfactory picture of the fluidized heat transfer process and may provide the beginnings of a rational approach to the correlation and prediction of fluidized heat transfer in engineering work.
Continuous stirred tank reactors: A new graphical method for complex reaction and reflux designs
Authors: Bilous Olegh , Piret Edgar L. 
Published: June 2004

AbstractThe usual graphical CSTR design methods are not adequate for the case of complex reactions involving competing or consecutive steps; therefore graphical design method based on the representation of batch data on a triangular diagram is given and illustrated by several examples. This method does not require a complete analysis of the kinetics of the reaction. Since material balances are easily represented on concentration spaces, the method is especially useful when the design includes recycling, or feed additions along reactor chain.
Kinetics of the liquid‐phase oxidation of ethanol
Authors: Klassen John , Kirk R. S. 
Published: June 2004

AbstractA study was made of the rate of liquid‐phase oxidation of ethanol to acetic acid. An aqueous, basic solution of ethanol was allowed to trickle over a palladium‐onalumina catalyst in a packed tower while oxygen‐containing gas was blown upward. The observed rates are described by an equation including a kinetic term and a mass transfer term for the diffusion of oxygen. Kinetic rate constants and gas‐ and liquid‐film mass transfer coefficients are reported.