bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Altering Aminoglycoside Structures on Bacterial Resistance Enzyme Activities
Authors: Green Keith D. , Chen Wenjing , Garneau-Tsodikova Sylvie 
Published: May 2011

ABSTRACT

Aminoglycoside-modifying enzymes (AMEs) constitute the most prevalent mechanism of resistance to aminoglycosides by bacteria. We show that aminoglycosides can be doubly modified by the sequential actions of AMEs, with the activity of the second AME in most cases unaffected, decreased, or completely abolished. We demonstrate that the bifunctional enzyme AAC(3)-Ib/AAC(6′)-Ib′ can diacetylate gentamicin. Since single acetylation does not always inactivate the parent drugs completely, two modifications likely provide more-robust inactivation
in vivo
.
Protein Binding: Do We Ever Learn?
Authors: Zeitlinger Markus A. , Derendorf Hartmut , Mouton Johan W. , Cars Otto , Craig William A. , Andes David , Theuretzbacher Ursula 
Published: May 2011

ABSTRACTAlthough the influence of protein binding (PB) on antibacterial activity has been reported for many antibiotics and over many years, there is currently no standardization for pharmacodynamic models that account for the impact of protein binding of antimicrobial agentsin vitro. This might explain the somewhat contradictory results obtained from different studies. Simplein vitromodels which compare the MIC obtained in protein-free standard medium versus a protein-rich medium are prone to methodological pitfalls and may lead to flawed conclusions. Withinin vitrotest systems, a range of test conditions, including source of protein, concentration of the tested antibiotic, temperature, pH, electrolytes, and supplements may influence the impact of protein binding. As new antibiotics with a high degree of protein binding are in clinical development, attention and action directed toward the optimization and standardization of testing the impact of protein binding on the activity of antibioticsin vitrobecome even more urgent. In addition, the quantitative relationship between the effects of protein bindingin vitroandin vivoneeds to be established, since the physiological conditions differ. General recommendations for testing the impact of protein bindingin vitroare suggested.
In Vitro
Activity of Ceftazidime-NXL104 against 396 Strains of β-Lactamase-Producing Anaerobes
Authors: Citron Diane M. , Tyrrell Kerin L. , Merriam Vreni , Goldstein Ellie J. C. 
Published: May 2011

ABSTRACT

NXL104, a novel β-lactamase inhibitor, was tested at a constant concentration of 4 μg/ml in combination with ceftazidime (CAZ), with and without added metronidazole, against 396 β-lactamase-producing strains of anaerobic bacteria. MIC
50
/MIC
90
values for
Bacteroides fragilis
and the
B. fragilis
group were 8/16 and 64/>128 μg/ml, respectively. Although CAZ-NXL104 had limited activity against most anaerobic strains, in combination with metronidazole it shows potential for treating mixed infections involving resistant
Enterobacteriaceae
and anaerobes.
Efficacy of Caspofungin in Neutropenic and Corticosteroid-Immunosuppressed Murine Models of Invasive Pulmonary Mucormycosis
Authors: Lewis Russell E. , Leventakos Konstantinos , Liao Guangling , Kontoyiannis Dimitrios P. 
Published: May 2011

ABSTRACT

Caspofungin (CFG) was tested in neutropenic and corticosteroid-immunosuppressed mice challenged with a lethal sinopulmonary inoculum of
Rhizopus oryzae
. Compared to untreated controls, CFG administered at 1 mg/kg of body weight/day significantly improved survival (54% versus 19%;
P
= 0.003) and reduced median
R. oryzae
fungal burden by 1.5 log
10
for conidial equivalent DNA in neutropenic but not corticosteroid-immunosuppressed animals. CFG administered at 16 mg/kg/day was not significantly better than a saline control for treatment of invasive pulmonary mucormycosis (IPM) in either neutropenic or corticosteroid-immunosuppressed animals.
Trimeric Autotransporter Adhesin-Dependent Adherence of Bartonella henselae, Bartonella quintana, and Yersinia enterocolitica to Matrix Components and Endothelial Cells under Static and Dynamic Flow Conditions
Authors: Müller Niklas F. , Kaiser Patrick O. , Linke Dirk , Schwarz Heinz , Riess Tanja , Schäfer Andrea , Eble Johannes A. , Kempf Volkhard A. J. 
Published: May 2011

ABSTRACT

Trimeric autotransporter adhesins (TAAs) are important virulence factors of Gram-negative bacteria responsible for adherence to extracellular matrix (ECM) and host cells. Here, we analyzed three different TAAs (
Bartonella
adhesin A [BadA] of
Bartonella henselae
, variably expressed outer membrane proteins [Vomps] of
Bartonella quintana
, and
Yersinia
adhesin A [YadA] of
Yersinia enterocolitica
) for mediating bacterial adherence to ECM and endothelial cells. Using static (cell culture vials) and dynamic (capillary flow chambers) experimental settings, adherence of wild-type bacteria and of the respective TAA-negative strains was analyzed. Under static conditions, ECM adherence of
B. henselae
,
B. quintana
, and
Y. enterocolitica
was strongly dependent on the expression of their particular TAAs. YadA of
Y. enterocolitica
did not mediate bacterial binding to plasma or cellular fibronectin under either static or dynamic conditions. TAA-dependent host cell adherence appeared more significant under dynamic conditions although the total number of bound bacteria was diminished compared to the number under static conditions. Dynamic models expand the methodology to perform bacterial adherence experiments under more realistic, bloodstream-like conditions and allow dissection of the biological role of TAAs in ECM and host cell adherence under static and dynamic conditions.
Fusobacterium nucleatum Infection of Colonic Cells Stimulates MUC2 Mucin and Tumor Necrosis Factor Alpha
Authors: Dharmani Poonam , Strauss Jaclyn , Ambrose Christian , Allen-Vercoe Emma , Chadee Kris 
Published: May 2011

ABSTRACTThe etiology of inflammatory bowel disease is not completely known, but it is influenced by the presence of normal gut microflora as well as yet-unrecognized pathogens. The anaerobic, Gram-negative bacterial speciesFusobacterium nucleatumis a common resident of the human mouth and gut and varies in its pathogenic potential. In this study, we demonstrate that highly invasiveF. nucleatumisolates derived from the inflamed guts of Crohn's disease patients evoked significantly greater MUC2 and tumor necrosis factor alpha (TNF-α) gene expression than minimally invasive strains isolated from the noninflamed gut in human colonic epithelial cells and in a rat ligated colonic loop model of infection. Only liveF. nucleatuminduced mucin secretion and TNF-α expression in direct contact with and/or during invasion of colonic cells. In rat colons, mucin secretion was augmented in response to a highly invasiveF. nucleatumisolate but was unaffected by treatment with a minimally invasive strain. Taken together, these studies reveal thatF. nucleatummay represent a challenging pathogen in the etiology of gut inflammatory diseases and highlight the importance of different pathotypes of candidate bacterial species in disease pathogenesis.
Reproductive success of cavity-nesting birds in partially harvested woodlots
Authors: Straus Melissa A. , Bavrlic Kata , Nol Erica , Burke Dawn M. , Elliott Ken A. 
Published: May 2011

Cavity-nesting birds are dependent on large declining and dead trees that are frequently removed during partial harvesting. We compared breeding densities, nest survival, nest site characteristics, food abundance, and reproductive parameters of six species of cavity-nesting birds in partially harvested and reference woodlots in southwestern Ontario, Canada. Silvicultural practices significantly altered woodlot structure, with treatment-specific effects on bark arthropod biomass, fledging dates for the Red-bellied Woodpecker ( Melanerpes carolinus (Linnaeus, 1758)), and site suitability for the Yellow-bellied Sapsucker ( Sphyrapicus varius (Linnaeus, 1766)). Red-bellied Woodpecker, Downy Woodpecker ( Picoides pubescens (Linnaeus, 1766)), and Hairy Woodpecker ( Picoides villosus (Linnaeus, 1766)) experienced lower breeding densities in recently cut sites. Daily survival rates were generally greater for nests positioned higher up in large trees and for Northern Flicker ( Colaptes auratus (Linnaeus, 1758)) nests excavated in healthy and hard wood. Conversely, the Black-capped Chickadee ( Poecile atricapillus (Linnaeus, 1766)) had higher daily survival rates in low, small trees (<10 cm diameter at breast height) and sites with lower arthropod abundance. We conclude that although partial harvesting has the potential to decrease cavity-nesting bird breeding densities, conscientious cavity tree retention during harvest may provide suitable nesting sites that maintain high rates of nest success, regardless of the silvicultural treatments that we examined. However, further research is required to monitor these trends beyond a single harvesting rotation.
Early effects of pre- and post-harvest herbicide application and partial cutting in regenerating aspen – jack pine mixtures in northeastern Ontario
Authors: Man Rongzhou , Rice James A. , MacDonald G. Blake 
Published: May 2011

Silvicultural options to obtain mixtures of broadleaved and conifer tree species in boreal forests remain limited, especially for mixtures of broadleaves and shade-intolerant conifers. In this study, we tested a series of treatment packages that included variation in harvesting pattern, site preparation, renewal treatments, and timing and patterns of tending to establish trembling aspen (Populus tremuloides Michx.) and jack pine (Pinus banksiana Lamb.) mixedwoods in intimate mixtures or spatial mosaics in northeastern Ontario. Preharvest spray resulted in fewer but better growth of aspen suckers compared with postharvest spray, which both reduced sucker density and decreased their vigour. Partial cutting reduced aspen regeneration in both the harvested and leave corridors but did not affect other broadleaved species, in this case predominantly red maple (Acer rubrum L.). After treatment, the rapid development of understory vegetation (shrubs, herbs, and grasses) and regeneration reduced total light transmittance at 0.5 m but had no effect at 4.0 m after 5 years. Future stands will be jack pine dominated following both pre- and post-harvest sprays, despite higher density, more uniform distribution, and better growth of broadleaved regeneration with preharvest spray, but will be balanced broadleaf and conifer mixtures in the partial cut areas.
Acetylsalicylate reduces endothelial and platelet-derived microparticles in patients with coronary artery disease
Authors: Bulut Daniel , Becker Vanessa , Mügge Andreas 
Published: May 2011

Previous studies suggest that endothelial progenitor cells (EPCs) contribute to vascular repair processes. In contrast, circulating microparticles (MPs) are reported to be part of a process that is damaging to vascular cells. Numerous studies suggest that the “balance” between EPCs and MPs is important for the integrity of vascular cells and preservation of endothelial function. In the present study, we assess the impact of acetylsalicylate (ASA) — which is, beside statins and physical exercise, a third basic column in the preventive therapy of coronary artery disease (CAD) — on EPCs and MPs in patients with CAD. We investigated the effect of treatment (8 weeks) with ASA (100 mg/d) on endothelial function (flow-mediated vasodilation, FMD), number of circulating EPCs, and endothelial- and platelet-derived microparticles (eMP, pMP) in 15 male patients (age 59.5 ± 12.3 years) with CAD but nonsignificant stenosis. The number of pMPs and eMPs decreased by 62.7% (p < 0.05) and 28.4% (p < 0.05), respectively. The number of circulating EPCs (VEGFR2+CD34+), expressed as ‰ of circulating polymorphonuclear leukocytes, remained unchanged. Despite the reduced number of pMPs and eMPs in response to the ASA therapy, the FMD responses and the maximal dilator effects of nitroglycerin were unaffected. In a control experiment, patients (n = 6) treated with the selective COX-2 inhibitor etoricoxib (90 mg/day) for 8 weeks showed no changes in the number of pMPs, eMPs, and EPCs and in FMD. We report on a novel effect of ASA treatment on the number of circulating endothelial- and platelet-derived microparticles in patients with cardiovascular disease. The mechanism remains elusive, and appears not to be associated with the COX-2 pathway.
Short-term in vivo inhibition of nitric oxide synthase with L-NAME influences the contractile function of single left ventricular myocytes in rats
Authors: Lunz Wellington , Natali Antônio José , Carneiro Miguel Araújo , dos Santos Aggum Capettini Luciano , Baldo Marcelo Perim , de Souza Matheus Ornelas , Quintão Judson Fonseca , Bozi Luiz Henrique Marchesi , Lemos Virginia Soares , Mill José Geraldo 
Published: May 2011

The main purpose of this study was to investigate the effects of short-term L-NAME treatment on the contractile function of left ventricle (LV) myocytes and the expression of proteins related to Ca2+ homeostasis. Data from Wistar rats treated with L-NAME (L group, n = 20; 0.7 g/L in drinking water; 7 days) were compared with results from untreated controls (C group, n = 20). Cardiomyocytes from the L group showed increased (p < 0.05) fractional shortening (23%) and maximum rate of shortening (20%) compared with the C group. LV from the L group also showed increased (p < 0.05) expression of the ryanodine receptor 2 and Na+/Ca2+ exchanger proteins (76% and 83%, respectively; p < 0.05). However, the L and C groups showed similar in vivo hemodynamic parameters of cardiac function. In conclusion, short-term NOS inhibition determines an increased expression of Ca2+ regulatory proteins, which contributes to improving cardiomyocyte contractile function, preserving left ventricular function.
The short-term consumption of a moderately high-fat diet alters nitric oxide bioavailability in lean female Zucker rats
Authors: Huang Kan , Huang Yue , Frankel Jessica , Addis Cassandra , Jaswani Lavina , Wehner Paulette S. , Mangiarua Elsa I. , McCumbee William D. 
Published: May 2011

To determine whether short-term consumption of a moderately high-fat diet (MHFD) affects nitric oxide (NO) production, the concentration of stable NO metabolites (NOx) in urine and plasma of rats fed a MHFD (15.6 %g fat) or control diet (4.5 %g fat) was measured weekly for 4 weeks. Plasma and urine NOx levels were significantly depressed in the MHFD group by week 1 and remained so for the duration of the study. Decreased NO bioavailability may result from a decrease in NO production or the scavenging of NO by reactive oxygen species (ROS). Because endothelial NOS (eNOS) is the major contributor to NO production and circulating levels of NOx, eNOS expression was measured in several tissues. At week 1, there was a MHFD-associated decrease in eNOS expression in the liver. Subsequently, eNOS expression declined in the heart and kidney medulla of MHFD-fed rats at weeks 3 and 4, respectively. The expression of eNOS in the kidney cortex and adipose tissue did not change. These results suggest that a MHFD alters eNOS expression in a time-dependent and tissue-specific manner. In the liver, NOS activity and tissue levels of NOx and nitrotyrosine were measured. Nitrotyrosine levels were used as an indirect measure of the NO scavenged by ROS. There was a decrease in NOS activity, suggesting that the low levels of hepatic NOx were due, in part, to a decrease in NO production. In addition, there was a dramatic increase in nitrotyrosine formation, suggesting that the decline in hepatic NOx was also due to an increased interaction of NO with ROS. Tyrosine nitration commonly has detrimental effects on proteins. The decrease in NO and increase in protein nitration could potentially have adverse effects on tissue function.
AN URBAN GROWTH MODEL BASED ON A CELLULAR AUTOMATA PHENOMENOLOGICAL FRAMEWORK
Authors: IANNONE G. , TROISI A. , GUARNACCIA C. , D'AGOSTINO P. P. , QUARTIERI J. 
Published: May 2011

In this paper we adopt a phenomenological approach in order to develop a suitable Cellular Automata (CA) model capable to satisfactory mimic city growth and urban sprawl. The use of CA in urban expansion modeling is well known since many years, but very rarely it has been related with a down-top approach which considers inhabitants' preferences as a driving tool to characterize the CA algorithm. In addition, we consider as a control mechanism of the cell conversion rate (i.e. the number of cells experiencing conversion into urban use) the logistic function. This function is tuned on the free space (cells) at disposal for the urban development. In this paper we present the basics of the model and we perform a simple simulation in the case of a generic geographic pattern.
MULTIFRACTAL ANALYSIS OF SCLEROGLUCAN HYDROGELS FOR DRUG DELIVERY
Authors: FRANÇOIS NORA J. , LOSADA M. PIACQUADIO , DARAIO MARTA E. 
Published: May 2011

The non-homogeneity and complexity of micro network distribution of hydrogel matrices prepared with two scleroglucan biopolymers obtained with different fermentation times were analyzed using environmental scanning electron microscopy (ESEM) and dynamic rheology. ESEM images were processed with the tools of multifractal theory using the box-counting method in order to obtain the gels multifractal spectra. Dynamic rheological measurements indicate that both polymeric networks correspond to physical gels that exhibit a solid like behavior. These results suggest the existence of a relationship between the fermentation time used in the polymer production, the degree of self-similarity and the rigidity of the scleroglucan gel structure.
Programming wireless sensor networks
Authors: Mottola Luca , Picco Gian Pietro 
Published: May 2011

Wireless sensor networks (WSNs) are attracting great interest in a number of application domains concerned with monitoring and control of physical phenomena, as they enable dense and untethered deployments at low cost and with unprecedented flexibility.
However, application development is still one of the main hurdles to a wide adoption of WSN technology. In current real-world WSN deployments, programming is typically carried out very close to the operating system, therefore requiring the programmer to focus on low-level system issues. This not only distracts the programmer from the application logic, but also requires a technical background rarely found among application domain experts. The need for appropriate high-level programming abstractions, capable of simplifying the programming chore without sacrificing efficiency, has long been recognized, and several solutions have hitherto been proposed, which differ along many dimensions.
In this article, we survey the state of the art in programming approaches for WSNs. We begin by presenting a taxonomy of WSN applications, to identify the fundamental requirements programming platforms must deal with. Then, we introduce a taxonomy of WSN programming approaches that captures the fundamental differences among existing solutions, and constitutes the core contribution of this article. Our presentation style relies on concrete examples and code snippets taken from programming platforms representative of the taxonomy dimensions being discussed. We use the taxonomy to provide an exhaustive classification of existing approaches. Moreover, we also map existing approaches back to the application requirements, therefore providing not only a complete view of the state of the art, but also useful insights for selecting the programming abstraction most appropriate to the application at hand.
Interactive editing of massive imagery made simple
Authors: Summa Brian , Scorzelli Giorgio , Jiang Ming , Bremer Peer-Timo , Pascucci Valerio 
Published: May 2011

This article presents a simple framework for progressive processing of high-resolution images with minimal resources. We demonstrate this framework's effectiveness by implementing an adaptive, multi-resolution solver for gradient-based image processing that, for the first time, is capable of handling gigapixel imagery in real time. With our system, artists can use commodity hardware to interactively edit massive imagery and apply complex operators, such as seamless cloning, panorama stitching, and tone mapping.
We introduce a progressive Poisson solver that processes images in a purely coarse-to-fine manner, providing near instantaneous global approximations for interactive display (see Figure 1). We also allow for data-driven adaptive refinements to locally emulate the effects of a global solution. These techniques, combined with a fast, cache-friendly data access mechanism, allow the user to interactively explore and edit massive imagery, with the illusion of having a full solution at hand. In particular, we demonstrate the interactive modification of gigapixel panoramas that previously required extensive offline processing. Even with massive satellite images surpassing a hundred gigapixels in size, we enable repeated interactive editing in a dynamically changing environment. Images at these scales are significantly beyond the purview of previous methods yet are processed interactively using our techniques. Finally our system provides a robust and scalable out-of-core solver that consistently offers high-quality solutions while maintaining strict control over system resources.
Fine-grained DVFS using on-chip regulators
Authors: Eyerman Stijn , Eeckhout Lieven 
Published: May 2011

Limit studies on Dynamic Voltage and Frequency Scaling (DVFS) provide apparently contradictory conclusions. On the one hand early limit studies report that DVFS is effective at large timescales (on the order of million(s) of cycles) with large scaling overheads (on the order of tens of microseconds), and they conclude that there is no need for small overhead DVFS at small timescales. Recent work on the other hand—motivated by the surge of on-chip voltage regulator research—explores the potential of fine-grained DVFS and reports substantial energy savings at timescales of hundreds of cycles (while assuming no scaling overhead).
This article unifies these apparently contradictory conclusions through a DVFS limit study that simultaneously explores timescale and scaling speed. We find that coarse-grained DVFS is unaffected by timescale and scaling speed, however, fine-grained DVFS may lead to substantial energy savings for memory-intensive workloads. Inspired by these insights, we subsequently propose a fine-grained microarchitecture-driven DVFS mechanism that scales down voltage and frequency upon individual off-chip memory accesses using on-chip regulators. Fine-grained DVFS reduces energy consumption by 12% on average and up to 23% over a collection of memory-intensive workloads for an aggressively clock-gated processor, while incurring an average 0.08% performance degradation (and at most 0.14%). We also demonstrate that the proposed fine-grained DVFS mechanism is orthogonal to existing coarse-grained DVFS policies, and further reduces energy by 6% on average and up to 11% for memory-intensive applications with limited performance impact (at most 0.7%).