bluuebunny/crossref_metadata_2025 huggingface dataset:
Aeroelastic Stability of Welded-in-Pair Low Pressure Turbine Rotor Blades: A Comparative Study Using Linear Methods
Authors: Corral Roque , Gallardo Juan Manuel , Vasco Carlos
Published: January 2007

The aerodynamic damping of a modern low pressure turbine bladed-disk with interlock rotor blades is compared for the first time to that obtained when the rotor blades are welded in pairs through the lateral face of the shroud. The damping is computed solving the linearized Reynolds averaged Navier-Stokes equations on a moving grid. First the basics of the stabilizing mechanism of welding the rotor blades in pairs is investigated using two-dimensional analyses and the Panovsky and Kielb method. It is concluded that the stabilizing effect is due to the suppression of unsteady perturbations in one out of the two passages providing for the first time a physical explanation to engine data. Three-dimensional effects are then studied using the actual mode shapes of two bladed disks differing solely in the shroud boundary conditions. It is concluded that the increase in the aerodynamic damping, due to the modification of the mode shapes caused by welding the rotor blades in pairs, is smaller than that due to the overall raise of the reduced frequencies of a bladed disk with an interlock design. The modification of the flutter boundaries due to mistuning effects is assessed using the reduced order model known as the Fundamental Mistuning Model. A novel extension of the critical reduced frequency stability maps accounting for mistuning effects is derived and applied for both, the freestanding and welded-in-pair airfoils. The stabilizing effect of mistuning is clearly seen in these maps. Finally, the effect of mistuning on low-pressure-turbine bladed disks is studied. It is shown that the modification on the stability limit of the interlock bladed disk is negligible, while for the welded-in-pair configuration a 0.15% increase of the damping relative to the critical damping is found. This qualitative difference between both configurations had not been reported before.
Experimental and Computational Comparisons of Fan-Shaped Film Cooling on a Turbine Vane Surface
Authors: Colban W. , Thole K. A. , Haendler M.
Published: January 2007

The flow exiting the combustor in a gas turbine engine is considerably hotter than the melting temperature of the turbine section components, of which the turbine nozzle guide vanes see the hottest gas temperatures. One method used to cool the vanes is to use rows of film-cooling holes to inject bleed air that is lower in temperature through an array of discrete holes onto the vane surface. The purpose of this study was to evaluate the row-by-row interaction of fan-shaped holes as compared to the performance of a single row of fan-shaped holes in the same locations. This study presents adiabatic film-cooling effectiveness measurements from a scaled-up, two-passage vane cascade. High-resolution film-cooling measurements were made with an infrared camera at a number of engine representative flow conditions. Computational fluid dynamics predictions were also made to evaluate the performance of some of the current turbulence models in predicting a complex flow such as turbine film-cooling. The renormalization group (RNG) k‐ε turbulence model gave a closer prediction of the overall level of film effectiveness, while the v2‐f turbulence model gave a more accurate representation of the flow physics seen in the experiments.
Improving Aerodynamic Matching of Axial Compressor Blading Using a Three-Dimensional Multistage Inverse Design Method
Authors: van Rooij M. P. C. , Dang T. Q. , Larosiliere L. M.
Published: January 2007

Current turbomachinery design systems increasingly rely on multistage CFD as a means to diagnose designs and assess performance potential. However, design weaknesses attributed to improper stage matching are addressed using often ineffective strategies involving a costly iterative loop between blading modification, revision of design intent, and further evaluation of aerodynamic performance. A scheme is proposed herein which greatly simplifies the design point blade row matching process. It is based on a three-dimensional viscous inverse method that has been extended to allow blading analysis and design in a multi-blade row environment. For computational expediency, blade row coupling is achieved through an averaging-plane approximation. To limit computational time, the inverse method was parallelized. The proposed method allows improvement of design point blade row matching by direct regulation of the circulation capacity of the blading within a multistage environment. During the design calculation, blade shapes are adjusted to account for inflow and outflow conditions while producing a prescribed pressure loading. Thus, it is computationally ensured that the intended pressure-loading distribution is consistent with the derived blading geometry operating in a multiblade row environment that accounts for certain blade row interactions. The viability of the method is demonstrated in design exercises involving the rotors of a 2.5 stage, highly loaded compressor. Individually redesigned rotors display mismatching when run in the 2.5 stage, evident as a deviation from design intent. However, simultaneous redesign of the rotors in their multistage environment produces the design intent, indicating that aerodynamic matching has been achieved.
CFD Analysis of the Radiation Distribution in a New Immobilized Catalyst Bubble Column Externally Illuminated Photoreactor
Authors: Trujillo Francisco J. , Safinski Tomasz , Adesina Adesoji A.
Published: January 2007

A new externally irradiated photoreactor configuration combining the excellent mass transfer characteristics of a bubble column operation with the separation power of an immobilized catalyst on quartz plates has been investigated using computational fluid dynamics (CFD) simulation. The radiative transport equation (RTE) in conjunction with the Navier-Stokes equations were solved to obtain the light incident radiative flux and the light absorbed by the immobilized titania as a function of the gas superficial velocity, the angle of inclination, and the separating distance between the plates. The model employed water and air as the fluid phases and the results indicated that gas bubbling considerably increased the incident radiation in the gas-liquid mixture enhancing the radiative flux and the absorbed radiation on the titania-coated plates. The CFD results pave the way for the optimization of a solar photocatalytic reactor for the degradation of organic pollutants.
Dynamic Models for Hydrogen Peroxide Control in Solar Photo-Fenton Systems
Authors: Alvarez J. D. , Gernjak W. , Malato S. , Berenguel M. , Fuerhacker M. , Yebra L. J.
Published: January 2007

Simulations and real decomposition experiments with hydrogen peroxide induced by dissolved iron and solar illumination were performed in a solar pilot plant with compound parabolic collectors designed for photo-Fenton wastewater treatment. The structure of a gray-box linear model aimed at reproducing system dynamics with parameters dependent on operating conditions when operating around prescribed set-points is proposed. This simple model relates the changes in hydrogen peroxide concentration due to changes in hydrogen peroxide injection, dissolved iron, and solar illumination. Based on this model, control of the hydrogen peroxide concentration at set points between 200-900mg∕L±10mg∕L under dynamic conditions (simultaneous decomposition and addition of hydrogen peroxide by a dosage pump), was achieved. Different basic approaches for controller actuation upon the frequency of the dosage pump were tested, ranging from a simple PI controller to a PI controller plus antiwindup action and feedforward control. From these basic approaches, conclusions can be drawn about the process’s behavior under closed-loop control.
Photo-Fenton Treatment of Olive Mill Wastewater Applying a Combined Fenton/Flocculation Pretreatment
Authors: Gernjak W. , Krutzler T. , Bauer R.
Published: January 2007

In this work, a pretreatment involving a combination of acidification, the Fenton method, and flocculation with polyelectrolytes was successfully applied to remove the suspended solids of Olive mill wastewater (OMW). This pretreatment strongly augmented the reaction rate in the following photo-Fenton treatment under solar irradiation in a Compound Parabolic Collector pilot-plant at Plataforma Solar de Almería. The content in phenolic substances could be degraded down to zero, while DOC was degraded down to about 25% of the initial value. In the work we describe different aspects concerning the process parameters of the pretreatment and the photo-Fenton treatment. Furthermore, decrease in phytotoxicity in the course of the treatment was monitored by germination tests with barley (hordeum vulgare L.). The results indicate that acute phytotoxicity can be substantially reduced by the application of the above mentioned pretreatment, enabling OMW to be used for ferti-irrigation in agriculture.
Intensification of Water Detoxification by Integrating Photocatalysis and Pervaporation
Authors: Camera-Roda G. , Santarelli F.
Published: January 2007

Many studies have been made on the possibility of increasing the efficiency of the photocatalytic detoxification of water streams, since for several practical applications the need for increasing the yield of the process is important. In the present work, the integration of photocatalysis with a membrane separation process is studied in order to analyze the possibility of enhancing the efficiency. It is experimentally shown that for the integrated process, the rate of disappearance of a model pollutant (4-chlorophenol) is highly improved. Then it is demonstrated that this “process intensification” takes place through synergetic mechanisms that are identified, discussed, and optimized.
Detoxification of Aqueous Solutions Containing the Commercial Pesticide Metasystox by TiO2-Mediated Solar Photocatalysis
Authors: Arques A. , García-Ripoll A. , Sanchís R. , Santos-Juanes L. , Amat A. M. , López M. F. , Miranda M. A.
Published: January 2007

A commercial pesticide, namely metasystox, has been chosen to study its detoxification in aqueous solution by means of solar photocatalysis employing titanium dioxide. Initial toxicity/biodegradability has been checked by means of active sludges respirometry and the Zahn–Wellens test. Laboratory scale experiments indicate that significant detoxification (by approximately one order of magnitude) of a 0.05g∕L solution of the active species can be achieved in only 3h of solar irradiation due to the nearly complete elimination of the active compound, methyloxydemeton. In this case, total organic carbon (TOC) measurements cannot be used to evaluate the process as nonactive organic excipients interfere in the measurement. The experiment has been scaled-up to 25L in a solar pilot plant; also in this case more than 75% elimination of methyloxydemeton is achieved in 5h irradiation (∼1400kJ). Besides detoxification (80% initial inhibition of the active sludges and 20% at the end of the experiments), and moderate TOC reduction (∼20%) are observed together with an increase of the surface tension of the solutions, probably due to elimination of excipients having surfactant properties.
Modeling the Solar Photocatalytic Degradation of Dyes
Authors: Villafán-Vidales H. I. , Cuevas S. A. , Arancibia-Bulnes C. A.
Published: January 2007

Background. The calculation of radiation absorption by the catalyst in solar photocatalytic reactors has been addressed by some authors, because it is a necessary step for the modeling of the detoxification of polluted water in these systems. Generally transparent pollutants have been considered, which somewhat simplifies the calculations. However, there has been an increasing interest in the study of solar photocatalytic degradation of dyes. These substances are not transparent to the radiation that the catalyst is able to absorb, and therefore their optical properties must be taken into account in the radiative modeling. Method of Approach. Absorption of radiation by the catalyst suspended in colored water is modeled by using the P1 approximation of radiative transfer theory. The absorption coefficient of the dye is taken into account in these calculations. A kinetic model is used to model degradation rates, based on the results of the radiative calculations. This has to be done through an Euler type method, because the reduction of dye concentration constantly modifies the optical conditions on the reactor, requiring a recalculation of radiation absorption at each step. Also, photocatalytic degradation experiments were carried out in a CPC solar photocatalytic reactor with tubular reaction space. Degradation of the Acid Orange 24 Azo dye was studied. The experimental degradation rates are compared with theoretical predictions. Results. An important influence of dye concentration is observed in the distribution of absorbed radiation, and also this parameter has a notorious effect on the predicted degradation rates. As a function of catalyst concentration, the degradation rate first increases rapidly and then at a smaller pace with an apparent linear trend. The experimental results can be reproduced well by the model. Conclusions. The proposed methodology allows modeling the solar photocatalytic degradation of dyes. The method should be applicable as long as the dye absorption coefficient is not too high in the wavelength region where the catalyst absorbs.
Solar Photocatalytic Decontamination of Phenol Using Pyrolytic TiO2 Films Deposited Inside Glass Tubing
Authors: Diaz José , Rodríguez Juan , Ponce Silvia , Solís José , Estrada Walter
Published: January 2007

Solar photocatalytic degradation of phenol was performed using TiO2 films deposited inside glass tubing by a spray-gel technique. Photocatalytic phenol degradation experiments were performed using either solar radiation or a 300W lamp simulating the UVA solar radiation component. In order to concentrate the radiation a reflective surface was placed in the rear part of the tube. The obtained TiO2 films were amorphous, but after annealing at 450°C for 1h, the films crystallized to the anatase structure and presented photocatalytic activity. The films’ morphology, observed by scanning electron microscopy, presented a uniform film and agglomerates of TiO2. The size of the agglomerates increases as Ti isopropoxide/ethanol molar ratio of the starting solution increases. The concentration of the precursor solution and the film thickness of TiO2 was optimized for phenol degradation. The TiO2 film obtained with a Ti-isopropoxide/ethanol molar ratio of 0.0259 and a film thickness between 1.2to2.4μm were shown to yield the highest phenol degradation.
Low-Cost TiO2
Photocatalytic Technology for Water Potabilization in Plastic Bottles For
Isolated Regions. Photocatalyst Fixation
Authors: Meichtry Jorge M. , Lin Hurng J. , de la Fuente Luciana , Levy Ivana K. , Gautier Eduardo A. , Blesa Miguel A. , Litter Marta I.
Published: January 2007

Experiments to evaluate the photocatalytic activity of supported TiO2 to potabilize water in common plastic PET bottles under solar irradiation were performed. Commercial titanium dioxide (Degussa P-25) was applied to different cheap materials—glass rings, glass rods and porcelain beads—by dip coating, or directly to the plastic wall of the bottles. The adherence and stability of TiO2 on the supports and the photocatalytic activity in bottles under solar irradiation was evaluated using model compounds as 4-chlorophenol and 2,4-dichlorophenoxyacetic acid. Rings were found to be the best glass supports, but PET bottles were superior for this specific application, as no fragile fillings are used, and the materials can be easily fabricated on site.
A Comparison of Solar Photocatalytic Inactivation of Waterborne E. coli Using Tris (2,2′-bipyridine)ruthenium(II), Rose Bengal, and TiO2
Authors: Rengifo-Herrera Julián A. , Sanabria Janeth , Machuca Fiderman , Dierolf Carlos F. , Pulgarin Cesar , Orellana Guillermo
Published: January 2007

Background. The development of alternative processes to eliminate pathogenic agents in water is a matter of growing interest. Current drinking water disinfection procedures, such as chlorination and ozonation, can generate disinfection by-products with carcinogenic and mutagenic potential and are not readily applicable in isolated rural communities of less-favored countries. Solar disinfection processes are of particular interest to water treatment in sunny regions of the Earth. Solar light may be used to activate a photocatalyst or photosensitizer that generates, in the presence of molecular oxygen dissolved in water, reactive oxygen species (ROS), such as the HO• radical, singlet oxygen (O21), or superoxide (O2•), which are toxic to waterborne microorganisms. Method of Approach. Wild and collection-type Escherichia coli have been selected as model bacteria. Inactivation of such bacteria by either TiO2 nanoparticles, water-soluble tris(2,2′-bipyridine)ruthenium(II) dichloride or Rose bengal (RB) subject to simulated sunlight have been compared. Although TiO2 is the prototypical material for heterogeneous photocatalysis, the other two dyes are known to generate significant amounts of O21 by photosensitization but have different chemical structures. The concentration of dye, illumination time, photostability, presence of scavengers, and post-treatment regrowth of bacteria have been investigated. Results. After 1hr of solar illumination the Ru(II) complex produced a strong loss of E. coli culturability monitored with solid selective agars. Both the collection- and wild-type bacteria are sensitive to the treatment with 2-10mgL−1 of dye. This photosensitizer showed a better inactivation effect than TiO2 and the anionic organic dye RB due to a combination of visible light absorption, photostability, and production of O21 and other ROS when bound to the bacterial membrane. A complete loss of culturability was observed when the initial concentration was 103CFUmL−1, with no bacteria regrowth detected after 24hr of the water treatment. At higher initial microorganism levels, culturability still remains and regrowth is observed. Scavengers show that the HO• radical is not involved in bacteria inactivation by photosensitization. Conclusions. A higher quantum yield of ROS generation by the sensitizing dyes compared to the semiconductor photocatalyst determines the faster sunlight-activated water disinfection of photodynamic processes. The homogeneous nature of the latter determines a more efficient interaction of the toxic intermediates with the target microorganisms. Solid supporting of the Ru(II) dye is expected to eliminate the potentials problems associated to the water-soluble dye.
Low-Oxygen-Recovery Assay for High-Throughput Screening of Compounds against Nonreplicating
Mycobacterium tuberculosis
Authors: Cho Sang Hyun , Warit Saradee , Wan Baojie , Hwang Chang Hwa , Pauli Guido F. , Franzblau Scott G.
Published: January 2007

Screening for new antimicrobial agents is routinely conducted only against actively replicating bacteria. However, it is now widely accepted that a physiological state of nonreplicating persistence (NRP) is responsible for antimicrobial tolerance in many bacterial infections. In tuberculosis, the key to shortening the 6-month regimen lies in targeting this NRP subpopulation. Therefore, a high-throughput, luminescence-based low-oxygen-recovery assay (LORA) was developed to screen antimicrobial agents against NRP
Mycobacterium tuberculosis. M. tuberculosis
H
37
Rv containing a plasmid with an acetamidase promoter driving a bacterial luciferase gene was adapted to low oxygen conditions by extended culture in a fermentor with a 0.5 headspace ratio. The MICs of 31 established antimicrobial agents were determined in microplate cultures maintained under anaerobic conditions for 10 days and, for comparative purposes, under aerobic conditions for 7 days. Cultures exposed to drugs under anaerobic conditions followed by 28 h of “recovery” under ambient oxygen produced a luminescent signal that was, for most compounds, proportional to the number of CFU determined prior to the recovery phase. No agents targeting the cell wall were active against NRP
M. tuberculosis
, whereas drugs hitting other cellular targets had a range of activities. The calculated
Z
′ factor was in the range of 0.58 to 0.84, indicating the suitability of the use of LORA for high-throughput assays. This LORA is sufficiently robust for use for primary high-throughput screening of compounds against NRP
M. tuberculosis
.
Rapid Genotyping of CTX-M Extended-Spectrum β-Lactamases by Denaturing High-Performance Liquid Chromatography
Authors: Xu Li , Evans Jason , Ling Thomas , Nye Kathy , Hawkey Peter
Published: January 2007

Denaturing high-performance liquid chromatography (dHPLC) is a powerful technique which has been used extensively to detect genetic variation. This is the first report of the application of dHPLC for rapid genotyping of bacterial β-lactamase genes. The technique was specifically developed to genotype members of all
bla
CTX-M
DNA homology groups. Thirteen well-defined
bla
CTX-M
extended-spectrum β-lactamase (ESBL)-producing strains were used to develop and optimize the dHPLC genotyping assay. Further evaluation was carried out with a blinded panel of 62 clinical isolates. The results of
bla
CTX-M
genotyping achieved by dHPLC were comparable to the typing results obtained by DNA sequencing. Applying the newly developed dHPLC-based genotyping method, we successfully genotyped all 73
bla
CTX-M
ESBL-producing strains from the 4-month survey study. Furthermore, we found the first reported cases in the United Kingdom of clinically significant disease caused by CTX-M-14- and CTX-M-1-producing
Escherichia coli
strains. We conclude that the novel dHPLC assay is highly accurate, rapid, and cost-effective for the genotyping of
bla
CTX-M
-producing ESBLs and has great potential for determining the clinical relevance of different and new
bla
CTX-M
genotypes, as well as for epidemiological studies and surveillance programs.
Pharmacokinetic Interaction between Darunavir Boosted with Ritonavir and Omeprazole or Ranitidine in Human Immunodeficiency Virus-Negative Healthy Volunteers
Authors: Sekar Vanitha J. , Lefebvre Eric , De Paepe Els , De Marez Tine , De Pauw Martine , Parys Wim , Hoetelmans Richard M. W.
Published: January 2007

Darunavir (DRV; TMC114; Prezista) is a human immunodeficiency virus (HIV) protease inhibitor used in combination with low-dose ritonavir (RTV) (DRV/r) as a pharmacokinetic enhancer. Protease inhibitor absorption may be decreased during coadministration of drugs that limit stomach acid secretion and increase gastric pH. This study was conducted to investigate the effect of ranitidine and omeprazole on the plasma pharmacokinetics of DRV and RTV in HIV-negative healthy volunteers. Sixteen volunteers completed the study and received DRV/r, DRV/r plus ranitidine, and DRV/r plus omeprazole, in three separate sessions. Treatment was given for 4 days with an additional morning dose on day 5, and regimens were separated by a washout period of 7 days. Samples were taken over a 12-h period on day 5 for the assessment of DRV and RTV plasma concentrations. Pharmacokinetic parameters assessed included DRV area under the curve, maximum plasma concentration, and trough plasma concentration. The least-squares mean ratios and 90% confidence intervals are reported with treatment of DRV/r alone as a reference. Compared with DRV/r alone, no significant changes in DRV pharmacokinetic parameters were observed during coadministration of DRV/r and either ranitidine or omeprazole. Treatment regimens were generally well tolerated, and no serious adverse events were reported. In conclusion, coadministration of DRV/r and ranitidine or omeprazole was well tolerated by the volunteers. Ranitidine and omeprazole did not have a significant influence on DRV pharmacokinetics. No dose adjustments are required when DRV/r is coadministered with omeprazole or ranitidine.
In Vitro Activity of the Oxazolidinone RWJ-416457 against Linezolid-Resistant and -Susceptible Staphylococci and Enterococci
Authors: Livermore David M. , Warner Marina , Mushtaq Shazad , North Sarah , Woodford Neil
Published: January 2007

RWJ-416457, a novel oxazolidinone, had modal MICs of 0.5 to 1 μg/ml for linezolid-susceptible staphylococci and enterococci, versus linezolid MICs for these organisms of 1 or 2 μg/ml. RWJ-416457 MICs for mutants with 23S rRNA mutations were 2 to 32 μg/ml, versus linezolid MICs of 8 to 64 μg/ml; actual values reflected the proportion of gene copies mutated.
Activity of Linezolid against 3,251 Strains of Uncommonly Isolated Gram-Positive Organisms: Report from the SENTRY Antimicrobial Surveillance Program
Authors: Jones Ronald N. , Stilwell Matthew G. , Hogan Patricia A. , Sheehan Daniel J.
Published: January 2007

Linezolid was tested against 32 species of uncommonly isolated gram-positive organisms (3,251 strains) by reference MIC methods and found to be highly active (MIC
50
range, 0.25 to 2 μg/ml; MIC
90
range, 0.25 to 2 μg/ml). Only one isolate (viridans group streptococcus; 0.03% of tested strains) was resistant to linezolid.
Peroxisome Function Regulates Growth on Glucose in the Basidiomycete Fungus
Cryptococcus neoformans
Authors: Idnurm Alexander , Giles Steven S. , Perfect John R. , Heitman Joseph
Published: January 2007

The function of the peroxisomes was examined in the pathogenic basidiomycete
Cryptococcus neoformans
. Recent studies reveal the glyoxylate pathway is required for virulence of diverse microbial pathogens of plants and animals. One exception is
C. neoformans
, in which isocitrate lyase (encoded by
ICL1
) was previously shown not to be required for virulence, and here this was extended to exclude also a role for malate synthase (encoded by
MLS1
). The role of peroxisomes, in which the glyoxylate pathway enzymes are localized in many organisms, was examined by mutation of two genes (
PEX1
and
PEX6
) encoding AAA (
A
TPases
a
ssociated with various cellular
a
ctivities)-type proteins required for peroxisome formation. The
pex1
and
pex6
deletion mutants were unable to localize the fluorescent DsRED-SKL protein to peroxisomal punctate structures, in contrast to wild-type cells.
pex1
and
pex6
single mutants and a
pex1 pex6
double mutant exhibit identical phenotypes, including abolished growth on fatty acids but no growth difference on acetate. Because both
icl1
and
mls1
mutants are unable to grow on acetate as the sole carbon source, these findings demonstrate that the glyoxylate pathway can function efficiently outside the peroxisome in
C. neoformans
. The
pex1
mutant exhibits wild-type virulence in a murine inhalation model and in an insect host, demonstrating that peroxisomes are not required for virulence under these conditions. An unusual phenotype of the
pex1
and
pex6
mutants was that they grew poorly with glucose as the carbon source, but nearly wild type with galactose, which suggested impaired hexokinase function and that
C. neoformans
peroxisomes might function analogously to the glycosomes of the trypanosomid parasites. Deletion of the hexokinase
HXK2
gene reduced growth in the presence of glucose and suppressed the growth defect of the
pex1
mutant on glucose. The hexokinase 2 protein of
C. neoformans
contains a predicted peroxisome targeting signal (type 2) motif; however, Hxk2 fused to fluorescent proteins was not localized to peroxisomes. Thus, we hypothesize that glucose or glycolytic metabolites are utilized in the peroxisome by an as yet unidentified enzyme or regulate a pathway required by the fungus in the absence of peroxisomes.
Molecular Systematics of Dictyostelids: 5.8S Ribosomal DNA and Internal Transcribed Spacer Region Analyses
Authors: Romeralo María , Escalante Ricardo , Sastre Leandro , Lado Carlos
Published: January 2007

The variability and adaptability of the amoebae from the class
Dictyosteliomycetes
greatly complicate their systematics. The nucleotide sequences of the ribosomal internal transcribed spacers and the 5.8S ribosomal DNA gene have been determined for 28 isolates, and their utility to discriminate between different species and genera has been shown.
Protection against Cryptococcosis by Using a Murine Gamma Interferon-ProducingCryptococcus neoformansStrain
Authors: Wormley Floyd L. , Perfect John R. , Steele Chad , Cox Gary M.
Published: January 2007

We evaluated cell-mediated immune (CMI) responses in mice given a pulmonary infection with aCryptococcus neoformansstrain engineered to produce the Th1-type cytokine gamma interferon (IFN-γ). Mice given a pulmonary infection with an IFN-γ-producingC. neoformansstrain were able to resolve the primary infection and demonstrated complete (100%) protection against a second pulmonary challenge with a pathogenicC. neoformansstrain. Pulmonary cytokine analyses showed that Th1-type/proinflammatory cytokine and chemokine expression were significantly higher and Th2-type cytokine expression was significantly lower in mice infected with the IFN-γ-producingC. neoformansstrain compared to wild-type-infected mice. This increased pulmonary Th1-type cytokine expression was also associated with significantly lower pulmonary fungal burden and significantly higher pulmonary leukocyte and T-lymphocyte recruitment in mice infected with the IFN-γ-producingC. neoformansstrain compared to wild-type-infected mice. Our results demonstrate that pulmonary infection of mice with aC. neoformansstrain expressing IFN-γ results in the stimulation of local Th1-type anti-cryptococcal CMI responses and the development of protective host immunity against future pulmonary cryptococcal infections. The use of fungi engineered to produce host cytokines is a novel method to study immune responses to infection and may be useful in developing vaccine strategies in humans.
Transcriptional and Proteomic Profiles of Group B
Streptococcus
Type V Reveal Potential Adherence Proteins Associated with High-Level Invasion
Authors: Johri Atul K. , Margarit Immaculada , Broenstrup Mark , Brettoni Cecilia , Hua Lei , Gygi Steven P. , Telford John L. , Grandi Guido , Paoletti Lawrence C.
Published: January 2007

Group B
Streptococcus
(GBS) is an opportunistic organism that can harmlessly colonize the human gut, vagina, and rectum but can also cause pneumonia, sepsis, and meningitis in neonates born to colonized mothers. We have shown previously that growth rate and oxygen level regulate the ability of GBS to invade eukaryotic cells in vitro. Herein we extend and expand on these observations to show that GBS type V, an emergent serotype, grown in a chemostat at a cell mass-doubling time (

t
d

) of 1.8 h with oxygen invaded human ME-180 cervical epithelial cells in large numbers compared with those grown at the same

t
d

without oxygen or at a slower

t
d

of 11.0 h. The fact that several GBS type V cell wall-associated and membrane proteins were expressed exclusively under the invasive growth condition prompted an investigation, using genomics and proteomics, of all upregulated genes and proteins. Several proteins with potential roles in adherence were identified, including an undefined surface antigen (SAG1350), a lipoprotein (SAG0971), penicillin-binding protein 2b (SAG0765), glyceraldehyde-3-phosphate dehydrogenase (SAG0823), and an iron-binding protein (SAG1007). Mouse antisera to these five proteins inhibited binding of GBS type V to ME-180 cells by ≥85%. Recombinant undefined surface antigen (SAG1350), lipoprotein (SAG0971), and penicillin-binding protein 2b (SAG0765) each bound to ME-180 cells in a dose-dependent fashion, confirming their ability to act as ligands. Collectively, these data increase the number of potential GBS adherence factors and also suggest a role for these surface-associated proteins in initial pathogenic events.
Mixed epithelial and stromal tumour of the kidney with luteinised ovarian stroma
Authors: Buritica C , Serrano M , Zuluaga A , Arrabal M , Regauer S , Nogales F F
Published: January 2007

We report a case of a 9-cm mixed epithelial and stromal tumour of the kidney in an obese 70-year-old woman with diabetes. The ovarian-type stroma had a spindle cell component that was positive for progesterone receptors and had the hitherto unreported presence of abundant foci of luteinised stromal cells with characteristic immunohistochemical positivity to α-inhibin, calretinin, aromatase and gonadotropin-releasing hormone (GnRH) receptors. We conclude that the stromal component is identical to ovarian cortical stroma.

We believe that ovarian-type stroma occurs in extragenital tumours as a result of an epithelial–stromal interaction in an environment of hormonal hyperstimulation.
Massive expansion of EBV+ monoclonal T cells with CD5 down regulation in EBV-associated haemophagocytic lymphohistiocytosis
Authors: Lin Ming-Tsan , Chang Hui-Mei , Huang Chang-Jen , Chen Woan-Ling , Lin Chi-Yung , Lin Ching-Yang , Chuang Shih-Sung
Published: January 2007

Haemophagocytic lymphohistiocytosis (HLH) comprises primary and secondary forms; the secondary form is most commonly triggered by the Epstein–Barr virus (EBV; EBV-HLH). Patients with EBV-HLH usually exhibit oligoclonal or monoclonal T cell proliferation, which may mimic T cell lymphoproliferative disorder (T-LPD). This article reports on EBV-HLH in a 17-month-old girl with an extreme surge of reactive T lymphocytosis (absolute count 167×109/l) with CD5 down regulation. Bone marrow aspirate and trephine contained florid haemophagocytosis and massive infiltration of CD3+ Epstein–Barr virus-encoded RNA+ lymphocytes, as seen by double labelling. These lymphocytes were monoclonal for EBV and T cell receptor γ chain gene rearrangement. The patient responded dramatically to intravenous immunoglobulin, interferon α2b, ganciclovir and prednisolone, suggesting restoration of her immune system and eradication of the clonal T cells through these immunoregulatory agents. Thus, careful clinicopathological correlation is warranted in the interpretation of immunophenotyping and clonality data in T cell proliferation in association with EBV-HLH to avoid erroneous diagnosis of T-LPD.
Non-atherosclerotic coronary pathology causing sudden death
Authors: De Giorgio Fabio , Abbate Antonio , Vetrugno Giuseppe , Capelli Arnaldo , Arena Vincenzo
Published: January 2007

Coronary atherosclerosis is responsible for >50% of all cases of sudden death and for 90% of sudden coronary death. Four cases encountered in routine autopsy evaluation at our institute in 2004 in which non-atherosclerotic coronary pathology was responsible for sudden cardiac death are reported. The cases of a 31-year-old man with epicardial coronary arteritis, a 57-year-old man with intramyocardial vasculitis, a 45-year-old woman with spontaneous coronary dissection and a 50-year-old man with vascular fibrosis are described. Searching for non-atherosclerotic coronary disease is relevant for both the clinician and the pathologist to prevent coronary causes of sudden death going unrecognised.
Immunohistological analysis of immune cells in blistering skin lesions
Authors: Hussein Mahmoud R , Ali Fayed Mahammad Nagy , Omar Abd-Elhady M M
Published: January 2007

Background:Bullous skin lesions are characterised by the presence of intraepidermal or subepidermal bullae. Although inflammatory cell infiltrate is a constant feature in these lesions, their immunophenotypic characterisation is still incomplete.

Aim:To determine whether the development of bullous skin diseases is associated with changes in the inflammatory cell infiltrate.

Materials and methods:34 cases representing lesions with both intraepidermal and subepidermal bullae were examined using immunoperoxidase staining methods and antibodies targeting antigens for histiocytes (CD68), B cells (CD20+), T cells (CD3+), T cells with cytotoxic potential (T cell intracellular associated antigen, TIA1+) and activity (granzyme B, GRB+). The adjacent normal skin (lesions) and an additional five cases of normal skin were also examined (controls).

Results:The transition from normal skin to lesional skin (lesions with intraepidermal and subepidermal bullae) was associated with a significant increase (p⩽0.05) in the density of total inflammatory cell infiltrate, CD68+ cells, CD3+ T lymphocytes, CD20+ B lymphocytes, TIA1+-resting cytotoxic T cells and GRB+ T cells with cytotoxic activity.

Conclusions:The increase in inflammatory cell infiltrate during the transition from normal to lesional skin may reflect the presence of an increased antigenicity of the lesional cells or a response to some basement membrane components. CD68+ and CD3+ cells, especially the resting cytotoxic ones, achieved numerical dominance in these lesions. Cell-mediated immunity seems to have critical role in the development of these lesions.
Satellite cell proliferation and skeletal muscle hypertrophy
Authors: Adams Gregory R.
Published: January 2007

Satellite cells are small, mononuclear cells found in close association with striated skeletal muscles cells (myofibers). These cells appear to function as reserve myoblasts. A critical role for these cells in the process of muscle regeneration following injury has been clearly established. In that role, satellite cells have been shown to proliferate extensively. Some of the progeny of these cells then fuse with each other to form replacement myofibers, whereas others return to quiescence, thereby maintaining this reserve population. In response to injury, activated satellite cells can also fuse with damaged but viable myofibers to promote repair and regeneration. It has also been observed that satellite cells are activated during periods of significantly increased muscle loading and that some of these cells fuse with apparently undamaged myofibers as part of the hypertrophy process. The observation that the inactivation of satellite cell proliferation prevents most of the hypertrophy response to chronic increases in loading has lead to the hypothesis that a limitation to the expansion of myofiber size is imposed by the number of myonuclei present. Recent evidence suggests that a potential limitation to muscle hypertrophy, in the absence of a reserve supply of myonuclei, may be the inability to sustain increases in ribosomes, thereby limiting translational capacity.
Exercise in the prevention and treatment of maternal–fetal disease: a review of the literature
Authors: Weissgerber Tracey L. , Wolfe Larry A. , Davies Gregory A.L. , Mottola Michelle F.
Published: January 2007

Evidence-based guidelines indicate that regular prenatal exercise is an important component of a healthy pregnancy. In addition to maintaining physical fitness, exercise may be beneficial in preventing or treating maternal–fetal diseases. Women who are the most physically active have the lowest prevalence of gestational diabetes (GDM), and prevention of GDM may decrease the incidence of obesity and type 2 diabetes in both mother and offspring. However, few studies have investigated the effectiveness of exercise in delaying or preventing GDM in at-risk women, and exercise prescriptions that optimize outcomes for women with GDM are lacking. Physically active women are also less likely to develop pre-eclampsia, and we have proposed the following 4 mechanisms that may explain this protective effect: enhanced placental growth and vascularity, reduced oxidative stress, reduced inflammation, and correction of disease-related endothelial dysfunction. Exercise may also prevent reproductive complications associated with maternal obesity. Obesity increases the risk of infertility and miscarriage, and weight loss programs that incorporate diet and exercise are a cost-effective fertility treatment that may also reduce the probability of obesity-related complications during pregnancy. Regular exercise following conception may prevent excessive gestational weight gain and reduce post-partum weight retention.
Pulmonary oedema following exercise in humans
Authors: Hodges Alastair N.H.
Published: January 2007

Sub-clinical transient pulmonary oedema has been observed following exercise in both animals and, to some degree, humans. It has been proposed that transient pulmonary oedema, resulting from either pulmonary capillary leakage or capillary stress failure, may limit diffusion in the lung during and after exercise. Initially, to determine the minimal tolerable FIO2 for subsequent work in hypoxia, 10 aerobically trained males (VO2 max, 57.2 ± 7.95 mL·kg–1·min–1; age, 29.6 ± 5.8 y; height, 181.1 ± 8.3 cm; mass, 79.4 ± 5.6 kg) performed graded cycling work to maximal effort under 4 conditions of varying FIO2 (21%, 18%, 15%, and 12%) in a randomized blinded fashion. VO2 max and minimal SaO2 were significantly reduced while breathing 15% and 12% oxygen (VO2 max, 48.2 ± 7.9 and 31.5 ± 7.4 mL·kg–1·min–1, respectively). In the 12% oxygen condition, the majority of the subjects were not able to complete maximal exercise without SaO2 falling below 70%. Subsequently, to determine if transient pulmonary oedema occurs after sustained exercise, 10 highly trained male athletes (VO2 max, 65.0 ± 7.5 mL·kg–1·min–1; age, 25.9 ± 4.7 y; height, 184.1 ± 8.2 cm; mass, 79.4 ± 9.5 kg) underwent assessment of lung density by quantified magnetic resonance imaging before and 54.0 ± 17.2 and 100.7 ± 15.1 min after 60 min of cycling exercise (61.6% ± 9.5% VO2 max). The same 10 subjects underwent an identical measure before and 55.6 ± 9.8 and 104.3 ± 9.1 min after 60 min of cycling exercise (65.4% ± 7.1% hypoxic VO2 max) in hypoxia (FIO2 = 15.0%). Two subjects demonstrated mild exercise-induced arterial hypoxaemia (EIAH) (minSaO2 = 94.5% and 93.8%), and 7 demonstrated moderate EIAH (minSaO2 = 91.4% ± 1.1%) during a preliminary VO2 max test in normoxia. No significant differences (p < 0.05) were found in lung density after exercise in either condition. Mean lung densities, measured once pre- and twice post-exercise, were 0.177 ± 0.019, 0.181 ± 0.019, and 0.173 ± 0.019 g·mL–1 in the normoxic condition, and 0.178 ± 0.021, 0.174 ± 0.022, and 0.176 ± 0.019 g·mL–1 in the hypoxic condition. These results indicate that transient interstitial pulmonary oedema does not occur following sustained steady-state cycling exercise in normoxia or hypoxia. This diminishes the likelihood of pulmonary capillary leakage as a mechanism of transient pulmonary oedema, and, in turn, as a mechanism for changes in SaO2 during sustained exercise.
Work of breathing is increased during exercise with the self-contained breathing apparatus regulator
Authors: Butcher Scott J. , Jones Richard L. , Eves Neil D. , Petersen Stewart R.
Published: January 2007

The self-contained breathing apparatus (SCBA) increases the expiratory pressure required to maintain high rates of ventilation, suggesting that the expiratory work of breathing (WOB) is increased; however, this has never been reported. The objective of this study, therefore, was to determine if the WOB is increased with the SCBA regulator (BA condition) compared with a low-resistance breathing valve (RV condition) during exercise. Twelve healthy male subjects underwent two randomized exercise trials, consisting of cycling at 150, 180, 210, and 240 W. Inspired and expired tidal volumes were measured using a body plethysmograph, whereas esophageal pressures were measured with an esophageal balloon. Modified Campbell diagrams were created to calculate the resistive and elastic components of WOB during inspiration and expiration. There were no differences in WOB between BA and RV conditions at 150 W. End-inspiratory and -expiratory lung volumes were elevated (p < 0.05) in the BA condition at higher ventilation rates, which increased inspiratory elastic work and decreased expiratory elastic work at 180 and 210 W (p < 0.05). At 240 W (VE = 112 ± 17 L·min–1 in the BA condition), active expiratory resistive work increased by 59% ± 51%, inspiratory elastic work increased by 26% ± 24%, and total WOB increased by 13% ± 12% in the BA condition (p < 0.05). The SCBA regulator causes an increase in the active expiratory resistive work to maintain high ventilatory rates and an increase inspiratory elastic work through an elevation in lung volumes.
Local cold acclimation during exercise and its effect on neuromuscular function of the hand
Authors: Geurts Carla L.M. , Sleivert Gordon G. , Cheung Stephen S.
Published: January 2007

Most acclimation research is performed on resting individuals, whereas in real life, cold exposure is often accompanied by physical activity. We examined the effects of 2 weeks of repeated cold exposure of the hand with or without an elevated core temperature from exercise on neuromuscular function of the first dorsal interosseus (FDI) muscle and manual performance of the hand. The experimental group (4 female, 6 male; age, 25.1 ± 6.9 y) cooled their hands in 8 °C water for 30 min daily while cycling (50% of heart rate reserve); the control group (4 female, 4 male; age, 25.1 ± 5.7 y) remained still. Manual function testing consisted of tactile sensitivity, grip strength, manual dexterity, and evoked twitch force in a custom-made myograph. Thermal sensation, skin temperature of index finger (Tif) and hand (Tfdi), as well as rectal temperature (Tre), were recorded daily. Tre increased significantly during bicycling, by 0.6 ± 0.2 °C. Minimal Tif and Tfdi of the groups combined increased significantly during exposure days from 8.7 ± 0.7 °C and 12.4 ± 2.8 °C to 10.1 ± 1.3 °C and 15.0 ± 3.0 °C, respectively (p = 0.04), with no significant difference between groups. Thermal ratings improved significantly on exposure days. Manual function was impaired with cooling, but with no significant difference between groups or across time. Deterioration of twitch characteristics with cooling did not change with repeated cold exposure. Although the increasing core temperature during cold water immersion changed the acute temperature response and thermal ratings, it had no effect on local cold acclimation or manual function.
Validity of the 3 min step test in moderate altitude: environmental temperature as a confounder
Authors: Chen Shu-Man , Wang Jung-Shi , Lee Wen-Chih , Hou Chien-Wen , Chen Chung-Yu , Laio Yi-Hung , Lin Ching-Hung , Kuo Chia-Hua
Published: January 2007

The 3 min step test is a widely used method to evaluate physical fitness, but whether this method is valid when performed at altitude is unknown. The purpose of this study was to examine the effect of altitude on the fitness score of the 3 min step test, and the role of ambient temperature in this effect. In study I, 11 healthy volunteers (aged 18.1 ± 1.1 years) performed a 3 min step test at sea level and at altitude (1950 m). Plasma lactate and stress hormones, as indicators of metabolic stress, were measured before and after the test. To determine the role of ambient temperature, we performed study II at sea level with the same step test simulating the altitude temperature condition (24 °C at high altitude versus 32 °C at sea level) with 23 subjects (aged 20.4 ± 0.4 y). In study I, plasma lactate of the subjects was elevated during the step test at sea level and to a greater extent at high altitude. Plasma cortisol and testosterone levels were elevated only at high altitude. However, the heart rate (HR) recovery after the step test was faster at high altitude than at sea level, producing a better physical fitness index. Furthermore, in study II, we demonstrated that the subjects who performed the 3 min step test at 24 °C exhibited faster HR recovery than at 32 °C. The current study therefore suggests that environmental conditions leading to temperature variation have strong confounding effects on the fitness score of the 3 min step test.