bluuebunny/crossref_metadata_2025 huggingface dataset:
A Flexible Evaluative Framework for Order Picking Systems
Authors: Chen Chien‐Ming , Gong Yeming , De Koster René B.M. , Van Nunen Jo A.E.E.
Published: March 2009

This paper develops a novel framework to evaluate the integral performance of order picking systems with different combinations of storage and order picking policies. The warehousing literature on order picking mostly considers minimizing either elapsed time or distance as the sole objective, whereas warehouse managers in a supply chain have to look beyond single‐dimensional performance and consider trade‐offs among different criteria. Thus managers still need a unified and efficient framework to select a portfolio of appropriate order picking policies from a multi‐criteria and contextual perspective. Our framework—combining data envelopment analysis, ranking and selection, and multiple comparisons—provides an efficient methodology to simultaneously analyze several interrelated problems in order picking systems with multiple performance attributes, such as service levels and operational costs. We demonstrate our approach through comprehensive evaluations of order picking policies in three low‐level, picker‐to‐parts rectangular warehouses facing demand variations.
If You Don't Know Where You're Going, You'll Wind up Somewhere Else: The Case of “Foreign Language Learning Disability”
Authors: Sparks Richard L.
Published: March 2009

Abstract: Despite the lack of empirical evidence, the term foreign language learning disability (FLLD) has become popular in the learning disabilities (LD) and foreign language literature. I contend that there is not a unique “disability” for foreign language learning and suggest instead that foreign language skills run along a continuum of very strong to very weak foreign language learners. To support my positions, I review problems with the definition and diagnostic criteria for LD. Then, I cite problems with the development and use of a logically consistent, easily operationalized, and empirically valid definition and diagnostic criteria for the FLLD concept and explain how proponents of this “disability” misuse the foreign language aptitude concept. Last, I detail implications for identifying students who exhibit foreign language learning problems, address policies that permit students to obtain waivers from or course substitutions for foreign language requirements, and describe issues hidden from foreign language educators because of the LD and FLLD concepts.
A Modified Spanish Sequence for Students With Language‐Based Learning Disabilities
Authors: Amend Amanda E. , Whitney Carolyn A. , Messuri Antonia T. , Furukawa Hideko
Published: March 2009

Abstract: A two‐semester modified Spanish sequence was designed to address the needs of college students with language‐based learning disabilities. This course featured reduced scope, an emphasis on tactile activities, metacognitive strategies, and adaptations to the presentation and practice of material. Performances on fall and spring semester‐end essays were examined to determine whether differences in written performance would be found between students in the modified (n=30) versus nonmodified sections (n=213). Results showed no statistically significant differences in either fall or spring written performance scores between the two groups. A significant decline in performance was found between the fall and spring semesters for the modified section. This article details the methodologies used to teach vocabulary, grammar, and writing to this population of students.
Foreign Language Anxiety and Heritage Students of Spanish: A Quantitative Study
Authors: Tallon Michael
Published: March 2009

Abstract: The purpose of this study was to investigate if heritage students of Spanish experience foreign language anxiety and, if so, what levels of anxiety they experience. The data were collected using the Foreign Language Classroom Anxiety Scale (FLCAS). A total of 413 students (209 heritage students and 204 nonheritage students) participated in this study. In general, the mean anxiety scores for the heritage students were lower than the mean anxiety scores for the nonheritage students, although there were a few instances when the heritage students actually had higher anxiety scores. In addition, the heritage students in this study reported lower anxiety scores than other college‐level students from previous studies reported in the literature that also used the FLCAS.
Impact of short‐term high‐fat feeding on glucose and insulin metabolism in young healthy men
Authors: Brøns Charlotte , Jensen Christine B. , Storgaard Heidi , Hiscock Natalie J. , White Andrew , Appel Julie S. , Jacobsen Stine , Nilsson Emma , Larsen Claus M. , Astrup Arne , Quistorff Bjørn , Vaag Allan
Published: March 2009

A high‐fat, high‐calorie diet is associated with obesity and type 2 diabetes. However, the relative contribution of metabolic defects to the development of hyperglycaemia and type 2 diabetes is controversial. Accumulation of excess fat in muscle and adipose tissue in insulin resistance and type 2 diabetes may be linked with defective mitochondrial oxidative phosphorylation. The aim of the current study was to investigate acute effects of short‐term fat overfeeding on glucose and insulin metabolism in young men. We studied the effects of 5 days’ high‐fat (60% energy) overfeeding (+50%) versus a control diet on hepatic and peripheral insulin action by a hyperinsulinaemic euglycaemic clamp, muscle mitochondrial function by 31P magnetic resonance spectroscopy, and gene expression by qrt‐PCR and microarray in 26 young men. Hepatic glucose production and fasting glucose levels increased significantly in response to overfeeding. However, peripheral insulin action, muscle mitochondrial function, and general and specific oxidative phosphorylation gene expression were unaffected by high‐fat feeding. Insulin secretion increased appropriately to compensate for hepatic, and not for peripheral, insulin resistance. High‐fat feeding increased fasting levels of plasma adiponectin, leptin and gastric inhibitory peptide (GIP). High‐fat overfeeding increases fasting glucose levels due to increased hepatic glucose production. The increased insulin secretion may compensate for hepatic insulin resistance possibly mediated by elevated GIP secretion. Increased insulin secretion precedes the development of peripheral insulin resistance, mitochondrial dysfunction and obesity in response to overfeeding, suggesting a role for insulin per se as well GIP, in the development of peripheral insulin resistance and obesity.
Episodic hypoxia induces long‐term facilitation of upper airway muscle activity in spontaneously breathing anaesthetized rats
Authors: Ryan Stephen , Nolan Philip
Published: March 2009

We performed these experiments to determine if repeated exposure to episodic hypoxia induces long term facilitation (LTF) in anaesthetized spontaneously breathing rats. A previous study in spontaneously breathing rats was unable to demonstrate evidence of LTF with repeated hypoxia, but this may have been due to the low number of hypoxic episodes used. We hypothesized that with sufficient exposure, episodic hypoxia LTF of genioglossus (GG), hyoglossus (HG) and diaphragm (Dia) activities would be elicited. Experiments were performed in 24 anaesthetized spontaneously breathing rats with intact vagi. Peak and tonic GG, HG and Dia EMG activities were recorded before, during and for 1 h following exposure to eight (n= 8) or three (n= 8) episodes of isocapnic hypoxia (= 0.1) each of 3 min duration. A third time control series was also performed with exposure to normoxia alone (= 0.28, n= 8). Short‐term potentiation of GG and HG muscle activity developed during the early period after repeated exposure to eight and three hypoxic episodes. LTF, however, occurred only after eight hypoxic episodes. This manifested as an increase in peak GG and Dia inspiratory muscle activity and tonic HG activity. LTF of respiratory breathing frequency was also induced, reflected by a reduction in inspiratory and expiratory time. These findings support our initial hypothesis that LTF in the anaesthetized, spontaneously breathing rat is dependent on the number of exposures to hypoxia and show that the responses to repetitive hypoxia are composed of both short and long‐term facilitatory changes.
Loss of functional K+ channels encoded by ether‐à‐go‐go‐related genes in mouse myometrium prior to labour onset
Authors: Greenwood I. A. , Yeung S. Y. , Tribe R. M. , Ohya S.
Published: March 2009

There is a growing appreciation that ion channels encoded by the ether‐à‐go‐go‐related gene family have a functional impact in smooth muscle in addition to their accepted role in cardiac myocytes and neurones. This study aimed to assess the expression of ERG1–3 (KCNH1–3) genes in the murine myometrium (smooth muscle layer of the uterus) and determine the functional impact of the ion channels encoded by these genes in pregnant and non‐pregnant animals. Quantitative RT‐PCR did not detect message for ERG2 and 3 in whole myometrial tissue extracts. In contrast, message for two isoforms of mERG1 were readily detected with mERG1a more abundant than mERG1b. In isometric tension studies of non‐pregnant myometrium, the ERG channel blockers dofetilide (1 μm), E4031 (1 μm) and Be‐KM1 (100 nm) increased spontaneous contractility and ERG activators (PD118057 and NS1643) inhibited spontaneous contractility. In contrast, neither ERG blockade nor activation had any effect on the inherent contractility in myometrium from late pregnant (19 days gestation) animals. Moreover, dofetilide‐sensitive K+ currents with distinctive ‘hooked’ kinetics were considerably smaller in uterine myocytes from late pregnant compared to non‐pregnant animals. Expression of mERG1 isoforms did not alter throughout gestation or upon delivery, but the expression of genes encoding auxillary subunits (KCNE) were up‐regulated considerably. This study provides the first evidence for a regulation of ERG‐encoded K+ channels as a precursor to late pregnancy physiological activity.
Wave Load and Structural Analysis for a Jack-Up Platform in Freak Waves
Authors: el Moctar Ould , Schellin Thomas E. , Jahnke Thomas , Peric Milovan
Published: March 2009

This paper analyzed the effects of freak waves on a mobile jack-up drilling platform stationed in exposed waters of the North Sea. Under freak wave conditions, highly nonlinear effects, such as wave run-up on platform legs and impact-related wave loads on the hull, had to be considered. Traditional methods based on the Morison formula needed to be critically examined to accurately predict these loads. Our analysis was based on the use of advanced computational fluid dynamics techniques. The code used here solves the Reynolds-averaged Navier–Stokes equations and relies on the interface-capturing technique of the volume-of-fluid type. It computed the two-phase flow of water and air to describe the physics associated with complex free-surface shapes with breaking waves and air trapping, hydrodynamic phenomena that had to be considered to yield reliable predictions. Lastly, the finite element method was used to apply the wave-induced loads onto a comprehensive finite element structural model of the platform, yielding deformations and stresses.
Physics process level discrimination of detections for GATE: Assessment of contamination in SPECT and spurious activity in PET
Authors: De Beenhouwer Jan , Staelens Steven , Vandenberghe Stefaan , Verhaeghe Jeroen , Van Holen Roel , Rault Erwann , Lemahieu Ignace
Published: March 2009

The GEANT4 application for tomographic emission (GATE) is one of the most detailed Monte Carlo simulation tools for SPECT and PET. It allows for realistic phantoms, complex decay schemes, and a large variety of detector geometries. However, only a fraction of the information in each particle history is available for postprocessing. In order to extend the analysis capabilities of GATE, a flexible framework was developed. This framework allows all detected events to be subdivided according to their type: In PET, true coincidences from others, and in SPECT, geometrically collimated photons from others. The framework of the authors can be applied to any isotope, phantom, and detector geometry available in GATE. It is designed to enhance the usability of GATE for the study of contamination and for the investigation of the properties of current and future prototype detectors. The authors apply the framework to a case study of Bexxar, first assuming labeling with , then with . It is shown that with PET, results with an optimized window improve upon those with the standard window but achieve less than half of the ideal improvement. Nevertheless, PET shows improved resolution compared to SPECT with triple‐energy‐window scatter correction.
Accuracy in breast shape alignment with 3D surface fitting algorithms
Authors: Riboldi Marco , Gierga David P. , Chen George TY , Baroni Guido
Published: March 2009

Surface imaging is in use in radiotherapy clinical practice for patient setup optimization and monitoring. Breast alignment is accomplished by searching for a tentative spatial correspondence between the reference and daily surface shape models. In this study, the authors quantify whole breast shape alignment by relying on texture features digitized on 3D surface models. Texture feature localization was validated through repeated measurements in a silicone breast phantom, mounted on a high precision mechanical stage. Clinical investigations on breast shape alignment included 133 fractions in 18 patients treated with accelerated partial breast irradiation. The breast shape was detected with a 3D video based surface imaging system so that breathing was compensated. An in‐house algorithm for breast alignment, based on surface fitting constrained by nipple matching (constrained surface fitting), was applied. Results were compared with a commercial software where no constraints are utilized (unconstrained surface fitting). Texture feature localization was validated within 2 mm in each anatomical direction. Clinical data show that unconstrained surface fitting achieves adequate accuracy in most cases, though nipple mismatch is considerably higher than residual surface distances (3.9 mm vs 0.6 mm on average). Outliers beyond 1 cm can be experienced as the result of a degenerate surface fit, where unconstrained surface fitting is not sufficient to establish spatial correspondence. In the constrained surface fitting algorithm, average surface mismatch within 1 mm was obtained when nipple position was forced to match in the [1.5; 5] mm range. In conclusion, optimal results can be obtained by trading off the desired overall surface congruence vs matching of selected landmarks (constraint). Constrained surface fitting is put forward to represent an improvement in setup accuracy for those applications where whole breast positional reproducibility is an issue.
Experimental investigation of the response of an EPID to an unflattened photon beam from an Elekta Precise linear accelerator
Authors: Tyner Elaine , McClean Brendan , McCavana Patrick , Wetterstedt Sacha af
Published: March 2009

The characteristics of an Elekta amorphous silicon electronic portal imaging device (EPID) in response to a 6 MV photon beam generated without a flattening filter, an unflattened beam, have been determined. The characteristics were then compared to those for a conventional photon beam generated with a flattening filter in the beam, a flattened beam, in order to determine the suitability of an EPID for transit dosimetry. The response of the EPID to the unflattened beam increased by 7.3% compared to the flattened beam, and copper buildup of 3 mm reduces the variation in the EPID response over air gaps ranging from 60 to 40 cm to within 2.5%. The scattering properties of the EPID with changing field size for the unflattened beam agree with those measured for a flattened beam to within 2%. Due to the minimal variation in the energy spectrum of the unflattened beam with the distance from the central axis, it was expected and experimentally found that the profile shape of the unflattened beam changes minimally with increasing phantom thickness. For an unflattened beam, EPID measured profiles with and without a phantom in the beam agree to within 2% using confidence limits. The difference between EPID and ionization chamber profiles measured at a depth of 5 cm in water is reduced compared to a flattened beam and remains unchanged with increasing phantom thickness. A difference of 4% was found between EPID profiles and the corresponding profiles measured with an ionization chamber measured in water over a range of phantom thickness. A calibration procedure was developed to convert EPID images to the equivalent absolute dose in water, at the EPID plane. A gamma evaluation was performed comparing the calibrated EPID images to dose measured with an ionization chamber array for rectangular fields and an IMRT segment. The fields were situated on axis and at 5 cm off axis with and without a 25 cm thick phantom in the beam. The gamma evaluation criteria of 3% and 3 mm were met within the field, for all fields examined. This study concludes that EPIDs are suitable dosimeters for IMRT treatments using unflattened photon beams with the advantage that the characteristics of the unflattened beam result in a reduction in the number of measurements necessary to calibrate an EPID as a transit dosimeter.
Mechanistic model of radiation‐induced cancer after fractionated radiotherapy using the linear‐quadratic formula
Authors: Schneider Uwe
Published: March 2009

A simple mechanistic model for predicting cancer induction after fractionated radiotherapy is developed. The model is based upon the linear‐quadratic model. The inductions of carcinomas and sarcomas are modeled separately. The linear‐quadratic model of cell kill is applied to normal tissues which are unintentionally irradiated during a cancer treatment with radiotherapy. Tumor induction is modeled such that each transformation process results in a tumor cell. The microscopic transformation parameter was chosen such that in the limit of low dose and acute exposure, the parameters of the linear‐no‐threshold model for tumor induction were approached. The differential equations describing carcinoma and sarcoma inductions can be solved analytically. Cancer induction in this model is a function of treatment dose, the cell kill parameters , the tumor induction variable , and the repopulation parameter . Carcinoma induction shows a bell shaped behavior as long as cell repopulation is small. Assuming large cell repopulation rates, a plateaulike function is approached. In contrast, sarcoma induction is negligible for low doses and increases with increasing dose up to a constant value. The proposed model describes carcinoma and sarcoma inductions after fractionated radiotherapy as an analytical function of four parameters. In the limit of low dose and for an instant irradiation it reproduces the results of the linear‐no‐threshold model. The obtained dose‐response curves for cancer induction can be implemented with other models such as the organ‐equivalent dose model to predict second cancers after radiotherapy.
Neutron spectra and dose equivalents calculated in tissue for high‐energy radiation therapy
Authors: Kry Stephen F. , Howell Rebecca M. , Salehpour Mohammad , Followill David S.
Published: March 2009

Neutrons are by‐products of high‐energy radiation therapy and a source of dose to normal tissues. Thus, the presence of neutrons increases a patient's risk of radiation‐induced secondary cancer. Although neutrons have been thoroughly studied in air, little research has been focused on neutrons at depths in the patient where radiosensitive structures may exist, resulting in wide variations in neutron dose equivalents between studies. In this study, we characterized properties of neutrons produced during high‐energy radiation therapy as a function of their depth in tissue and for different field sizes and different source‐to‐surface distances (SSD). We used a previously developed Monte Carlo model of an accelerator operated at 18 MV to calculate the neutron fluences, energy spectra, quality factors, and dose equivalents in air and in tissue at depths ranging from 0.1 to 25 cm. In conjunction with the sharply decreasing dose equivalent with increased depth in tissue, the authors found that the neutron energy spectrum changed drastically as a function of depth in tissue. The neutron fluence decreased gradually as the depth increased, while the average neutron energy decreased sharply with increasing depth until a depth of approximately 7.5 cm in tissue, after which it remained nearly constant. There was minimal variation in the quality factor as a function of depth. At a given depth in tissue, the neutron dose equivalent increased slightly with increasing field size and decreasing SSD; however, the percentage depth‐dose equivalent curve remained constant outside the primary photon field. Because the neutron dose equivalent, fluence, and energy spectrum changed substantially with depth in tissue, we concluded that when the neutron dose equivalent is being determined at a depth within a patient, the spectrum and quality factor used should be appropriate for depth rather than for in‐air conditions. Alternately, an appropriate percent depth‐dose equivalent curve should be used to correct the dose equivalent at the patient surface.
Evaluation of correction methods for coil‐induced intensity inhomogeneities and their influence on trabecular bone structure parameters from MR images
Authors: Folkesson Jenny , Krug Roland , Goldenstein Janet , Issever Ahi S. , Fang Charles , Link Thomas M. , Majumdar Sharmila
Published: March 2009

Magnetic resonance (MR) imaging‐based quantitative trabecular bone structure analysis has gained increasing interest in osteoporotic fracture risk assessment and treatment evaluation related to osteoporosis. In vivo MR images of anatomic regions such as the proximal femur and distal tibia are generally acquired with a surface coil in order to obtain sufficient sensitivity and resolution for quantification of the trabeculae. However, these coils introduce intensity inhomogeneities which affect the trabecular bone structure analysis. This work evaluates the applicability of a fully automatic coil correction by nonparametric nonuniform intensity normalization (N3) in the analysis of trabecular bone parameters. The ability to correct for coil‐induced intensity inhomogeneity was evaluated ex vivo on proximal femur specimens scanned with both a surface coil and a volume coil, which allowed for a direct evaluation of the performance of the coil correction methods without any major confounding factors. In addition, trabecular bone parameter values were correlated with values from high‐resolution peripheral computed tomography (HR‐pQCT) scans, and the reproducibility of trabecular bone parameters was evaluated in an in vivo study of repeat hip MR scans. The trabecular bone parameters determined from MR surface coil scans processed with the N3 coil correction method showed significant correlation with corresponding values from homogeneous intensity data in the ex vivo study. This can be compared to the correlation without coil correction , and coil correction using low‐pass filtering (LPF) . The in vivo interscan variability was reduced from 8.9% to 12.8% using LPF‐based to 3.6%–8.4% (CV) using N3 coil correction; hence the results showed that N3 is advantageous to LPF‐based coil correction. No significant differences in correlation to HR‐pQCT data were found for the coil correction methods. The significant correlations with volume coil data and high reproducibility of the N3 processed data imply that N3 coil correction preserve image information while accurately correcting for coil‐induced intensity inhomogeneities, which makes it suitable for quantitative analysis of trabecular bone structure from MR images acquired with surface coils.
Genomewide Identification of Genetic Determinants of Antimicrobial Drug Resistance inPseudomonas aeruginosa
Authors: Dötsch Andreas , Becker Tanja , Pommerenke Claudia , Magnowska Zofia , Jänsch Lothar , Häussler Susanne
Published: March 2009

The emergence of antimicrobial drug resistance is of enormous public concern due to the increased risk of delayed treatment of infections, the increased length of hospital stays, the substantial increase in the cost of care, and the high risk of fatal outcomes. A prerequisite for the development of effective therapy alternatives is a detailed understanding of the diversity of bacterial mechanisms that underlie drug resistance, especially for problematic gram-negative bacteria such asPseudomonas aeruginosa. This pathogen has impressive chromosomally encoded mechanisms of intrinsic resistance, as well as the potential to mutate, gaining resistance to current antibiotics. In this study we have screened the comprehensive nonredundant Harvard PA14 library forP. aeruginosamutants that exhibited either increased or decreased resistance against 19 antibiotics commonly used in the clinic. This approach identified several genes whose inactivation sensitized the bacteria to a broad spectrum of different antimicrobials and uncovered novel genetic determinants of resistance to various classes of antibiotics. Knowledge of the enhancement of bacterial susceptibility to existing antibiotics and of novel resistance markers or modifiers of resistance expression may lay the foundation for effective therapy alternatives and will be the basis for the development of new strategies in the control of problematic multiresistant gram-negative bacteria.
Concentrations of Voriconazole in Healthy and Inflamed Lung in Rats
Authors: Joukhadar Christian , Thallinger Christiane , Pöppl Wolfgang , Kovar Florian , Konz Karl H. , Joukhadar Samir M. , Traunmüller Friederike
Published: March 2009

By utilizing the microdialysis technique, we investigated the pharmacokinetic profile of voriconazole in the interstitium of the lungs and skeletal muscle tissue of rats after a single intravenous dose under healthy and inflammatory conditions. As expected, voriconazole penetrated excellently into the interstitium of tissues, and its levels were descriptively almost identical to free concentration-versus-time profiles in plasma.
Genetic Analysis of Colistin Resistance in
Salmonella enterica
Serovar Typhimurium
Authors: Sun Song , Negrea Aurel , Rhen Mikael , Andersson Dan I.
Published: March 2009

Colistin is a cyclic cationic peptide that kills gram-negative bacteria by interacting with and disrupting the outer membrane. We isolated 44 independent mutants in
Salmonella enterica
serovar Typhimurium with reduced susceptibility to colistin and identified 27 different missense mutations located in the
pmrA
and
pmrB
genes (encoding the regulator and sensor of a two-component regulatory system) that conferred increased resistance. By comparison of the two homologous sensor kinases, PmrB and EnvZ, the 22 missense mutations identified in
pmrB
were shown to be located in four different structural domains of the protein. All five
pmrA
mutations were located in the phosphate receiver domain of the regulator protein. The mutants appeared at a mutation rate of 0.6 × 10
−6
per cell per generation. The MICs of colistin for the mutants increased 2- to 35-fold, and the extent of killing was reduced several orders of magnitude compared to the susceptible strain. The growth rates of the mutants were slightly reduced in both rich medium and M9-glycerol minimal medium, whereas growth in mice appeared unaffected by the
pmrA
and
pmrB
mutations. The low fitness costs and the high mutation rate suggest that mutants with reduced susceptibility to colistin could emerge in clinical settings.
Emergence and Evolution of Multiply Antibiotic-ResistantSalmonella entericaSerovar Paratyphi Bd-Tartrate-Utilizing Strains Containing SGI1
Authors: Djordjevic Steven P. , Cain Amy K. , Evershed Nick J. , Falconer Linda , Levings Renee S. , Lightfoot Diane , Hall Ruth M.
Published: March 2009

The first Australian isolate ofSalmonella entericaserovar Paratyphi Bd-tartrate-utilizing (dT+) that is resistant to ampicillin, chloramphenicol, florfenicol, streptomycin, spectinomycin, sulfonamides, and tetracycline (ApCmFlSmSpSuTc) and contains SGI1 was isolated from a patient with gastroenteritis in early 1995. This is the earliest reported isolation globally. The incidence of infections caused by these SGI1-containing multiply antibiotic-resistantS. entericaserovar Paratyphi B dT+strains increased during the next few years and occurred sporadically in all states of Australia. Several molecular criteria were used to show that the early isolates are very closely related to one another and to strains isolated during the following few years and in 2000 and 2003 from home aquariums and their owners. Early isolates from travelers returning from Indonesia shared the same features. Thus, they appear to represent a true clone arising from a single cell that acquired SGI1. Some minor differences in the resistance profiles and molecular profiles also were observed, indicating the ongoing evolution of the clone, and phage type differences were common, indicating that this is not a useful epidemiological marker over time. Three isolates from 1995, 1998, and 1999 contained a completesul1gene but were susceptible to sulfamethoxazole due to a point mutation that creates a premature termination codon. This SGI1 type was designated SGI1-R. The loss of resistance genes also was examined. When strains were grown for many generations in the absence of antibiotic selection, the loss of SGI1 was not detected. However, variants SGI1-C (resistance profile SmSpSu) and SGI1-B (resistant to ApSu), which had lost part of the integron, arose spontaneously, presumably via homologous recombination between duplications in the In104 complex integron.
Galleria mellonella
as a Model System To Study
Acinetobacter baumannii
Pathogenesis and Therapeutics
Authors: Peleg Anton Y. , Jara Sebastian , Monga Divya , Eliopoulos George M. , Moellering Robert C. , Mylonakis Eleftherios
Published: March 2009

Nonmammalian model systems of infection such as
Galleria mellonella
(caterpillars of the greater wax moth) have significant logistical and ethical advantages over mammalian models. In this study, we utilize
G. mellonella
caterpillars to study host-pathogen interactions with the gram-negative organism
Acinetobacter baumannii
and determine the utility of this infection model to study antibacterial efficacy. After infecting
G. mellonella
caterpillars with a reference
A. baumannii
strain, we observed that the rate of
G. mellonella
killing was dependent on the infection inoculum and the incubation temperature postinfection, with greater killing at 37°C than at 30°C (
P
= 0.01).
A. baumannii
strains caused greater killing than the less-pathogenic species
Acinetobacter baylyi
and
Acinetobacter lwoffii
(
P
< 0.001). Community-acquired
A. baumannii
caused greater killing than a reference hospital-acquired strain (
P
< 0.01). Reduced levels of production of the quorum-sensing molecule 3-hydroxy-C
12
-homoserine lactone caused no change in
A. baumannii
virulence against
G. mellonella
. Treatment of a lethal
A. baumannii
infection with antibiotics that had in vitro activity against the infecting
A. baumannii
strain significantly prolonged the survival of
G. mellonella
caterpillars compared with treatment with antibiotics to which the bacteria were resistant.
G. mellonella
is a relatively simple, nonmammalian model system that can be used to facilitate the in vivo study of host-pathogen interactions in
A. baumannii
and the efficacy of antibacterial agents.
Localized Th1-, Th2-, T Regulatory Cell-, and Inflammation-Associated Hepatic and Pulmonary Immune Responses inAscaris suum-Infected Swine Are Increased by Retinoic Acid
Authors: Dawson Harry , Solano-Aguilar Gloria , Beal Madeline , Beshah Ethiopia , Vangimalla Vandana , Jones Eudora , Botero Sebastian , Urban Joseph F.
Published: March 2009

Pigs infected withAscaris suumor controls were given 100 μg (low-dose) or 1,000 μg (high-dose) all-transretinoic acid (ATRA)/kg body weight in corn oil or corn oil alone per os on days after inoculation (DAI) −1, +1, and +3 with infective eggs. Treatment with ATRA increased interleukin 4 (IL4) and IL12p70 in plasma of infected pigs at 7 DAI and augmented bronchoalveolar lavage (BAL) eosinophilia observed at 7 and 14 DAI. To explore potential molecular mechanisms underlying these observations, a quantitative real-time reverse transcription (RT)-PCR array was used to examine mRNA expression in tissue.Ascaris-infected pigs had increased levels of liver mRNA for T-helper-2 (Th2)-associated cytokines, mast cell markers, and T regulatory (Treg) cells, while infected pigs given ATRA had higherIL4,IL13,CCL11,CCL26,CCL17,CCL22, andTPSB1expression. Gene expression for Th1-associated markers (IFNG,IL12B, andTBX21), the CXCR3 ligand (CXCL9),IL1B, and the putative Treg markerTNFRSF18was also increased. Expression ofIL4,IL13,IL1B,IL6,CCL11, andCCL26was increased in the lungs of infected pigs treated with ATRA. To determine a putative cellular source of eosinophil chemoattractants, alveolar macrophages were treated with IL4 and/or ATRA in vitro. IL4 inducedCCL11,CCL17,CCL22, andCCL26mRNA, and ATRA increased the basal and IL4-stimulated expression ofCCL17andCCL22. Thus, ATRA augments a diverse Th1-, Th2-, Treg-, and inflammation-associated response in swine infected withA. suum, and the increased BAL eosinophilia may be related to enhanced induction of eosinophil chemokine activity by alveolar macrophages.
Campylobacter jejuni
-Induced Activation of Dendritic Cells Involves Cooperative Signaling through Toll-Like Receptor 4 (TLR4)-MyD88 and TLR4-TRIF Axes
Authors: Rathinam Vijay A. K. , Appledorn Daniel M. , Hoag Kathleen A. , Amalfitano Andrea , Mansfield Linda S.
Published: March 2009

Campylobacter jejuni
is an important cause of human enteritis and has been linked to the development of autoimmune diseases. Recently we showed that infection of murine dendritic cells (DCs) with
C. jejuni
resulted in DC activation and induction of
Campylobacter
-specific Th1-effector responses. Toll-like receptor (TLR) signaling through myeloid differentiation factor 88 (MyD88) and/or Toll-interleukin 1 (IL-1) receptor domain-containing adaptor-inducing beta interferon (IFN-β) (TRIF) is critical in inducing immunity against pathogens. In this study, we investigated the role of TLR2, TLR4, MyD88, and TRIF signaling in
C. jejuni
-induced inflammatory activation of DCs. DC upregulation of major histocompatibility complex class II and costimulatory molecules after
C. jejuni
challenge was profoundly impaired by TLR2, TLR4, MyD88, and TRIF deficiencies. Similarly,
C. jejuni
-induced secretion of IL-12, IL-6, and tumor necrosis factor alpha was significantly inhibited in TLR2
−/−
, TLR4
−/−
, MyD88
−/−
, and TRIF
−/−
DCs compared to that in wild-type DCs; however, the magnitude of inhibition was greater in MyD88
−/−
, TRIF
−/−
, and TLR4
−/−
DCs than in TLR2
−/−
DCs. Furthermore,
C. jejuni
induced interferon regulatory factor 3 phosphorylation and IFN-β secretion by DCs in a TLR4-TRIF-dependent fashion, further demonstrating activation of this pathway by
C. jejuni
. Importantly, TLR2, TLR4, MyD88, and TRIF deficiencies all markedly impaired the Th1-priming ability of
C. jejuni
-infected DCs. Thus, our results show that cooperative signaling through the TLR4-MyD88 and TLR4-TRIF axes represents a novel mechanism mediating
C. jejuni
-induced inflammatory responses of DCs. To our knowledge, such a mechanism has not been demonstrated previously for an intact bacterium.
Does intrusive growth of fusiform initials really contribute to circumferential growth of vascular cambium?
Authors: Włoch Wiesław , Jura-Morawiec Joanna , Kojs Paweł , Iqbal Muhammad , Krawczyszyn Józef
Published: March 2009

Currently it is believed that intrusive growth of fusiform cambial initials adds to the circumference of the cambial cylinder: the initial cells multiplied by anticlinal divisions are produced in excess, and the excess cells are later eliminated from the cambial surface. The present study, dealing with the intrusive growth of fusiform initials in the cambium of Laburnum anagyroides Medik, suggests that addition of a radial file of initials owing to intrusive growth, or elimination of any such file, has no visible effect on the tangential dimensions of a given cambial sector, and that intrusive growth of fusiform initials and the elimination of excess initials occur in unison. The two events complement each other, and the gain in size of the growing fusiform cell is accompanied by a reduction in size of its neighbour cell, thus keeping the tangential dimensions of the cambium unchanged. Our findings on L. anagyroides find support from illustrations of previous studies, which we have re-examined and re-interpreted. Our data suggest that increase in the cambial circumference is largely due to the symplastic growth of the fusiform initials in tangential direction.
Undifilum, a new genus for endophyticEmbellisia oxytropisand parasiticHelminthosporium bornmuellerion legumes
Authors: Pryor B. M. , Creamer R. , Shoemaker R. A. , McLain-Romero J. , Hambleton S.
Published: March 2009

Fungal endophytes of Oxytropis kansuensis Bunge from China, previously described as Embellisia oxytropis Q. Wang, Nagao & Kakish, and endophytes of Oxytropis sericea Nutt. and Oxytropis lambertii Pursh from the United States were compared and are reported here as conspecific members of a new genus in the Pleosporaceae, Undifilum, based on morphological and molecular analyses. Morphological comparisons revealed characters that are similar to those of the genus Embellisia including conidia ovate to obclavate to long ellipsoid, straight or slightly to decidedly inequilateral with occasionally one or two cells distinctly swollen, and transepta occasionally thickened, dark, and rigid in comparison with the exterior conidium wall. However, upon germination, conidia produced unique and diagnostic germ tubes that were wavy or undulating in their growth until branching. Moreover, all isolates were found to produce the toxic alkaloid swainsonine. Parsimony analysis of sequences from ITS1–5.8S–ITS2, glyceraldehyde-3-phosphate dehydrogenase gene, and mitochondrial small subunit rDNA data sets revealed that the Oxytropis endophytes formed a clade distinct from other Embellisia species and species in the genera Alternaria , Ulocladium , Nimbya , and Crivellia . A second taxon, Helminthosporium bornmuelleri P. Magnus, was reexamined and found to possess similar morphological features to those of the Oxytropis isolates, but lacked swainsonine production. Sequence analysis placed this second taxon in the same clade with high bootstrap support. The distinct morphology and genetics of these taxa demonstrates that these fungi, both recovered from legumes, represent a new genus, hereinafter described as Undifilum . The two species now placed in this genus are redescribed as Undifilium oxytropis and Undifilium bornmuelleri .
Downslope Soil Movement at a Sub-Arctic Location With Regard to Variations with Depth
Authors: Williams P J
Published: March 2009

Soil movements resulting from solifluction or similar processes have been investigated at Schefferville, P.Q., Canada, where the variation of movement with depth below the surface was specially considered.Tubes up to 2 m long were inserted vertically in the ground and their subsequent deformation (if any) measured with special probes, which passed down the tubes in situ. Some sites proved to be entirely stable despite vegetational characteristics that might have been related to disturbance. Movements at the surface of more than 10 cm/yr. were recorded on a 20° bare slope covered with small stones.Similar large movements were recorded on a lobate terrace-like feature with a general 8 to 10° slope. The distribution of movement with depth was such as to produce a typically concave downslope form in the tubes. The movements varied in intensity and from year to year; they decreased with depth, and were not measurable below about 1 m. Although they are similar to those observed by Rapp and others, they are remarkable in view of the slight slope on which they occurred. Analysis shows that consolidation following frost heave is probably not the sole cause. A stability calculation of the type commonly used for engineering purposes would have given no indication of the occurrence of movements of the magnitude observed. They might have been suspected, however, from geomorphological considerations of the origin of the surface features of the affected area.
Laboratory Consolidation of Some Normally Consolidated Soils
Authors: Raymond Gerald Patrick
Published: March 2009

A theory of consolidation is developed assuming:[Formula: see text]Solutions are given for the case of a thin bed of clay subjected to an instantaneous load increment. It is shown how the soil parameters may be obtained from standard laboratory consolidation tests. It is intended to discuss the application of the theory to field cases in a later paper.One-dimensional drainage tests performed in both the oedometer and triaxial cell are presented. The tests in the triaxial cell were performed using hydrostatic loading. The laboratory work was conducted on some remoulded New South Wales soils, some artificially deposited North American soils, and some undisturbed Ontario soils using instantaneous loading and large load ratios. Discussion is mainly illustrated with the tests performed on the artificially deposited soils.The propounded theory was found to be in reasonable but not complete agreement with the test results.D'Arcy's law was found to be valid for the soils tested.
Analysis of freezing in buds of Douglas-fir seedlings by simultaneous detection of ultrasonic emissions and differential thermal analysis
Authors: Stushnoff Cecil , Tinus Richard W. , Esensee Virgil D.
Published: March 2009

Differential thermal analysis is used to detect low-temperature exotherms, the nucleation of supercooled aqueous fractions, indicative of lethal freezing temperature in certain plant tissues. However, in plant tissues that do not supercool at low temperatures, there has been no analytical technique to detect events during lethal freezing. Simultaneous detection of ultrasonic emissions and differential thermal analysis exotherms provides a method to determine the lethal freezing temperature in lateral buds of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seedlings in the nonhardy and in the hardy condition. Ultrasonic emissions were detected in buds that supercooled at low temperatures and in those that did not. Simultaneous detection of ultrasonic emissions and differential thermal analysis is more sensitive than differential scanning calorimetry. Neither the precise source nor the nature of molecular perturbations associated with the release of ultrasonic emissions during freezing injury is known.
Seasonal responses of leaf gas exchange to elevated carbon dioxide in Populusgrandidentata
Authors: Curtis Peter S. , Teeri James A.
Published: March 2009

Rising atmospheric carbon dioxide concentrations may have important consequences for forest ecosystems. We studied above- and below-ground growth and leaf gas exchange responses of Populusgrandidentata Michx. to elevated CO2 under natural forest conditions over the course of a growing season. Recently emerged P. grandidentata seedlings were grown in native, nutrient-poor soils at ambient and twice ambient (707 μbar (1 bar = 100 kPa)) CO2 partial pressure for 70 days in open-top chambers in northern lower Michigan. Total leaf area and shoot and root dry weight all increased in high CO2 grown plants. Photosynthetic light and CO2 response characteristics were measured 28, 45, and 68 days after exposure to elevated CO2. In ambient grown plants, light saturated assimilation rates increased from day 28 to day 45 and then declined at day 68 (15 September). This late-season decline, typical of senescing Populus leaves, was due both to a decrease in the initial slope of the net CO2 assimilation versus intercellular CO2 partial pressure relationship and to decreased CO2 saturated assimilation rates. Specific leaf nitrogen (mg N•(cm2 leaf area)−1) did not change during this period, although leaf carbon content and leaf weight (mg•cm−2) both increased. In ambient grown plants stomatal conductance also declined at day 68. In contrast, plants grown at elevated CO2 showed no late-season decline in photosynthetic capacity or changes in leaf weight, suggesting a delay in senescence with long-term exposure to high CO2. High CO2 grown plants also maintained photosynthetic sensitivity to increasing Ci throughout the exposure period, while ambient CO2 grown plants were insensitive to Ci above 400 μbar on day 68. These results indicate the potential for direct CO2 fertilization of P. grandidentata in the field and provide evidence for a new mechanism by which elevated atmospheric CO2 could influence seasonal carbon gain.
Snow ablation in small forest openings in southwest Alberta
Authors: Berry G.J. , Rothwell R.L.
Published: March 2009

Snow ablation in circular forest openings 0, 1,3, and 5 H in diameter (where H is the average height of adjacent uncut trees (21 m)) was measured in early to mid-April, using snow pans with perforated false bottoms to allow measurement of melt and evaporation. Snowmelt accounted for 70 to 90% of total ablation. Evaporation was small, primarily because meteorological conditions were not favourable. Ablation rates were lower in the 1 H opening than in the 0, 3, and 5 H openings. The 1 H openings were colder because net radiation in the uncut forest and larger openings was 3 to 4 times greater. Wind speeds in the larger openings were 7 times greater than in the 0 and 1 H openings. Daily snowmelt rates in 0 and 1 H openings varied from 0 to 5 mm/day compared with 7 to 20 mm/day in 3 and 5 H openings. Meteorological data indicated that snow ablation was affected by advective energy transfer within openings and between the openings and surrounding forest. Ambient weather suggested that conditions favourable for advection occurred 24 to 53% of the daylight hours during the study period, and that advection was more important in the larger openings.