bluuebunny/crossref_metadata_2025 huggingface dataset:
Development, Evaluation, and Application of an
In Silico
Model for Antimalarial Drug Treatment and Failure
Authors: Winter Katherine , Hastings Ian M.
Published: May 2011

Pharmacological mechanism-based modeling was refined and used to develop an
in silico
model of antimalarial drug treatment validated against clinical and field data. We used this approach to investigate key features of antimalarial drug action and effectiveness, with emphasis on the current generation of artemisinin combination therapies. We made the following conclusions. (i) The development of artemisinin tolerance and resistance will, unless checked, have an immediate, large impact on the protection afforded to its partner drug and on the likely clinical efficacy of artemisinin combination therapies. (ii) Long follow-up periods are required in clinical trials to detect all drug failures; the follow-up periods of 28 days recommended by the World Health Organization are likely to miss at least 50% of drug failures, and we confirmed recent suggestions that 63 days would be a more appropriate follow-up period. (iii) Day 7 serum drug concentrations are a significant risk factor of failure, although, paradoxically, receiver operating characteristic curve analysis revealed that their predictive power is relatively poor. (iv) The pharmacokinetic properties of the partner drugs in artemisinin-containing combination therapies are the most important determinants of treatment outcome, particularly the maximum killing rate. We discuss the assumptions made in such modeling approaches and how similar approaches may be refined in future work.
Azithromycin Inhibits Expression of the GacA-Dependent Small RNAs RsmY and RsmZ in Pseudomonas aeruginosa
Authors: Pérez-Martínez Isabel , Haas Dieter
Published: May 2011

Azithromycin at clinically relevant doses does not inhibit planktonic growth of the opportunistic pathogen
Pseudomonas aeruginosa
but causes markedly reduced formation of biofilms and quorum-sensing-regulated extracellular virulence factors. In the Gac/Rsm signal transduction pathway, which acts upstream of the quorum-sensing machinery in
P. aeruginosa
, the GacA-dependent untranslated small RNAs RsmY and RsmZ are key regulatory elements. As azithromycin treatment and mutational inactivation of
gacA
have strikingly similar phenotypic consequences, the effect of azithromycin on
rsmY
and
rsmZ
expression was investigated. In planktonically growing cells, the antibiotic strongly inhibited the expression of both small RNA genes but did not affect the expression of the housekeeping gene
proC
. The azithromycin treatment resulted in reduced expression of
gacA
and
rsmA
, which are known positive regulators of
rsmY
and
rsmZ
, and of the PA0588-PA0584 gene cluster, which was discovered as a novel positive regulatory element involved in
rsmY
and
rsmZ
expression. Deletion of this cluster resulted in diminished ability of
P. aeruginosa
to produce pyocyanin and to swarm. The results of this study indicate that azithromycin inhibits
rsmY
and
rsmZ
transcription indirectly by lowering the expression of positive regulators of these small RNA genes.
Spermidine Synthase Is Required for Virulence of Leishmania donovani
Authors: Gilroy Caslin , Olenyik Tamara , Roberts Sigrid C. , Ullman Buddy
Published: May 2011

Genetic lesions in the polyamine biosynthetic pathway of
Leishmania donovani
, the causal agent of visceral leishmaniasis, are conditionally lethal mutations that render the insect vector form of the parasite auxotrophic for polyamines. Recently, we have demonstrated that a Δ
odc
L. donovani
null mutant lacking ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine biosynthesis, was profoundly compromised in its ability to infect mice, indicating that ODC is essential for the infectious mammalian stage of the parasite and further validating the enzyme as a possible drug target. To assess whether other components of the polyamine biosynthetic pathway were also essential for parasite virulence, a cell line deficient in spermidine synthase (SPDSYN), the enzyme that converts putrescine to spermidine, was created by double-targeted gene replacement within a virulent
L. donovani
background. This Δ
spdsyn
strain was auxotrophic for polyamines, required spermidine for growth in its insect vector form, and was adversely impacted in its ability to infect mice. These findings establish that SPDSYN, like ODC, is essential for maintaining a robust infection in mammals and indicate that pharmacologic inhibition of SPDSYN, and perhaps all components of the polyamine biosynthetic pathway, is a valid therapeutic strategy for the treatment of visceral and, potentially, other forms of leishmaniasis.
Porphyromonas gingivalis Induction of MicroRNA-203 Expression Controls Suppressor of Cytokine Signaling 3 in Gingival Epithelial Cells
Authors: Moffatt Catherine E. , Lamont Richard J.
Published: May 2011

Porphyromonas gingivalis
is a pathogen in severe periodontal disease. Able to exploit an intracellular lifestyle within primary gingival epithelial cells (GECs), a reservoir of
P. gingivalis
can persist within the gingival epithelia. This process is facilitated by manipulation of the host cell signal transduction cascades which can impact cell cycle, cell death, and cytokine responses. Using microarrays, we investigated the ability of
P. gingivalis
33277 to regulate microRNA (miRNA) expression in GECs. One of several miRNAs differentially regulated by GECs in the presence of
P. gingivalis
was miRNA-203 (miR-203), which was upregulated 4-fold compared to uninfected controls. Differential regulation of miR-203 was confirmed by quantitative reverse transcription-PCR (qRT-PCR). Putative targets of miR-203, suppressor of cytokine signaling 3 (SOCS3) and SOCS6, were evaluated by qRT-PCR. SOCS3 and SOCS6 mRNA levels were reduced >5-fold and >2-fold, respectively, in
P. gingivalis
-infected GECs compared to controls. Silencing of miR-203 using a small interfering RNA construct reversed the inhibition of SOCS3 expression. A dual luciferase assay confirmed binding of miR-203 to the putative target binding site of the SOCS3 3′ untranslated region. Western blot analysis demonstrated that activation of signal transducer and activator of transcription 3 (Stat3), a downstream target of SOCS, was diminished following miR-203 silencing. This study shows that induction of miRNAs by
P. gingivalis
can modulate important host signaling responses.
Anaplasma phagocytophilum Infects Mast Cells via α1,3-Fucosylated but Not Sialylated Glycans and Inhibits IgE-Mediated Cytokine Production and Histamine Release
Authors: Ojogun Nore , Barnstein Brian , Huang Bernice , Oskeritzian Carole A. , Homeister Jonathon W. , Miller Daniel , Ryan John J. , Carlyon Jason A.
Published: May 2011

Mast cells are sentinels for infection. Upon exposure to pathogens, they release their stores of proinflammatory cytokines, chemokines, and histamine. Mast cells are also important for the control of certain tick-borne infections.
Anaplasma phagocytophilum
is an obligate intracellular tick-transmitted bacterium that infects neutrophils to cause the emerging disease granulocytic anaplasmosis.
A. phagocytophilum
adhesion to and infection of neutrophils depend on sialylated and α1,3-fucosylated glycans. We investigated the hypotheses that
A. phagocytophilum
invades mast cells and inhibits mast cell activation. We demonstrate that
A. phagocytophilum
binds and/or infects murine bone marrow-derived mast cells (BMMCs), murine peritoneal mast cells, and human skin-derived mast cells.
A. phagocytophilum
infection of BMMCs depends on α1,3-fucosylated, but not sialylated, glycans.
A. phagocytophilum
binding to and invasion of BMMCs do not elicit proinflammatory cytokine secretion. Moreover,
A. phagocytophilum
-infected cells are inhibited in the release of tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), IL-13, and histamine following stimulation with IgE or antigen. Thus,
A. phagocytophilum
mitigates mast cell activation. These findings potentially represent a novel means by which
A. phagocytophilum
usurps host defense mechanisms and shed light on the interplay between mast cells and vector-borne bacterial pathogens.
SlyA Is a Transcriptional Regulator Involved in the Virulence of Enterococcus faecalis
Authors: Michaux Charlotte , Sanguinetti Maurizio , Reffuveille Fany , Auffray Yanick , Posteraro Brunella , Gilmore Michael S. , Hartke Axel , Giard Jean-Christophe
Published: May 2011

Phylogenetic analysis of the crystal structure of the
Enterococcus faecalis
SlyA (EF_3002) transcriptional factor places it between the SlyA and MarR regulator subfamilies. Proteins of these families are often involved in the regulation of genes important for bacterial virulence and stress response. To gather evidence for the role of this putative regulator in
E. faecalis
biology, we dissected the genetic organization of the
slyA
-EF_3001 locus and constructed a
slyA
deletion mutant as well as complemented strains. Interestingly, compared to the wild-type parent, the Δ
slyA
mutant is more virulent in an insect infection model (
Galleria mellonella
), exhibits increased persistence in mouse kidneys and liver, and survives better inside peritoneal macrophages. In order to identify a possible SlyA regulon, global microarray transcriptional analysis was performed. This study revealed that the
slyA
-EF_3001 locus appears to be autoregulated and that 117 genes were differentially regulated in the Δ
slyA
mutant. In the mutant strain, 111 were underexpressed and 6 overexpressed, indicating that SlyA functions mainly as an activator of transcription.
Enhancement of Neutrophil Function by Interleukin-18 Therapy Protects Burn-Injured Mice from Methicillin-Resistant Staphylococcus aureus
Authors: Kinoshita Manabu , Miyazaki Hiromi , Ono Satoshi , Inatsu Akihito , Nakashima Hiroyuki , Tsujimoto Hironori , Shinomiya Nariyoshi , Saitoh Daizoh , Seki Shuhji
Published: May 2011

Methicillin-resistantStaphylococcus aureus(MRSA) infection is a grave concern in burn-injured patients. We investigated the efficacy of interleukin-18 (IL-18) treatment in postburn MRSA infection. Alternate-day injections of IL-18 into burn-injured C57BL/6 mice significantly increased their survival after MRSA infection and after methicillin-sensitiveS. aureusinfection. Although IL-18 treatment of burn-injured mice augmented natural IgM production before MRSA infection and gamma interferon (IFN-γ) production after MRSA infection, neither IgM nor IFN-γ significantly contributed to the improvement in mouse survival. IL-18 treatment increased/restored the serum tumor necrosis factor (TNF), IL-17, IL-23, granulocyte colony-stimulating factor (G-CSF), and macrophage inflammatory protein (MIP-2) levels, as well as the neutrophil count, after MRSA infection of burn-injured mice; it also improved impaired neutrophil functions, phagocytic activity, production of reactive oxygen species, and MRSA-killing activity. However, IL-18 treatment was ineffective against MRSA infection in both burn- and sham-injured neutropenic mice. Enhancement of neutrophil functions by IL-18 was also observedin vitro. Furthermore, when neutrophils from IL-18-treated burn-injured mice were adoptively transferred into nontreated burn-injured mice 2 days after MRSA challenge, survival of the recipient mice increased. NOD-SCID mice that have functionally intact neutrophils and macrophages (but not T, B, or NK cells) were substantially resistant to MRSA infection. IL-18 treatment increased the survival of NOD-SCID mice after burn injury and MRSA infection. An adoptive transfer of neutrophils using NOD-SCID mice also showed a beneficial effect of IL-18-activated neutrophils, similar to that seen in C57BL/6 mice. Thus, although neutrophil functions were impaired in burn-injured mice, IL-18 therapy markedly activated neutrophil functions, thereby increasing survival from postburn MRSA infection.
The Nasal Dendritic Cell-Targeting Flt3 Ligand as a Safe Adjuvant Elicits Effective Protection against Fatal Pneumococcal Pneumonia
Authors: Kataoka Kosuke , Fujihashi Kohtaro , Oma Keita , Fukuyama Yoshiko , Hollingshead Susan K. , Sekine Shinichi , Kawabata Shigetada , Ito Hiro-O , Briles David E. , Oishi Kazunori
Published: May 2011

We have previously shown that a pneumococcal surface protein A (PspA)-based vaccine containing DNA plasmid encoding the Flt3 ligand (FL) gene (pFL) as a nasal adjuvant prevented nasal carriage ofStreptococcus pneumoniae. In this study, we further investigated the safety and efficacy of this nasal vaccine for the induction of PspA-specific antibody (Ab) responses against lung infection withS. pneumoniae.C57BL/6 mice were nasally immunized with recombinant PspA/Rx1 (rPspA) plus pFL three times at weekly intervals. When dynamic translocation of pFL was initially examined, nasal pFL was taken up by nasal dendritic cells (DCs) and epithelial cells (nECs) but not in the central nervous systems, including olfactory nerve and epithelium. Of importance, nasal pFL induced FL protein synthesis with minimum levels of inflammatory cytokines in the nasal washes (NWs) and bronchoalveolar lavage fluid (BALF). NWs and BALF as well as plasma of mice given nasal rPspA plus pFL contained increased levels of rPspA-specific secretory IgA and IgG Ab responses that were correlated with elevated numbers of CD8+and CD11b+DCs and interleukin 2 (IL-2)- and IL-4-producing CD4+T cells in the nasal mucosa-associated lymphoid tissues (NALT) and cervical lymph nodes (CLNs). Thein vivoprotection by rPspA-specific Abs was evident in markedly reduced numbers of CFU in the lungs, airway secretions, and blood when mice were nasally challenged withStreptococcus pneumoniaeWU2. Our findings show that nasal pFL is a safe and effective mucosal adjuvant for the enhancement of bacterial antigen (Ag) (rPspA)-specific protective immunity through DC-induced Th2-type and IL-2 cytokine responses.
Increased knee valgus alignment and moment during single-leg landing after overhead stroke as a potential risk factor of anterior cruciate ligament injury in badminton
Authors: Kimura Yuka , Ishibashi Yasuyuki , Tsuda Eiichi , Yamamoto Yuji , Hayashi Yoshimitsu , Sato Shuichi
Published: May 2011

Background

In badminton, knees opposite to the racket-hand side received anterior cruciate ligament (ACL) injuries during single-leg landing after overhead stroke. Most of them occurred in the backhand-side of the rear court. Comparing lower limb biomechanics during single-leg landing after overhead stroke between the forehand-side and backhand-side court may help explain the different injury rates depending on court position.

Hypothesis

The knee kinematics and kinetics during single-leg landing after overhead stroke following back-stepping were different between the forehand-side and backhand-side court.

Study design

Controlled laboratory study.

Methods

Hip, knee and ankle joint kinematic and knee kinetic data were collected for 17 right-handed female college badminton players using a 3-dimensional motion analysis system. Subjects performed single-left-legged landing after an overhead stroke following left and right back-stepping. The kinematic and kinetic data of the left lower extremities during landing were measured and compared between left and right back-steps.

Results

Hip flexion and abduction and knee valgus at the initial contact, hip and knee flexion and knee valgus at the maximum knee flexion and the maximum knee valgus moment were significantly larger for the left back-step than the right back-step (p<0.05).

Conclusion

Significant differences in joint kinematics and kinetics of the lower extremity during single-leg landing after overhead stroke were observed between different back-step directions. Increased knee valgus angle and moment following back-stepping to the backhand-side might be related to the higher incidence of ACL injury during single-leg landing after overhead stroke.
Picea rubensgrowth at high versus low elevations in the Great Smoky Mountains National Park: evaluation by systems modeling
Authors: Koo Kyung-Ah , Patten Bernard C. , Creed Irena F.
Published: May 2011

For half a century, red spruce ( Picea rubens Sarg.), a commercially and ecologically important boreal tree species, has experienced growth decline and high mortality in eastern North America. A tree growth systems model, ARIM (annual radial increment model), was developed to evaluate responsible factors for red spruce growth in the Great Smoky Mountains National Park. The dominant cause at higher elevations (1800–2000 m) was found to be air pollution involving high-frequency acidic rain and cloud immersion. The identified causes at lower elevations (1450–1700 m) were insufficient solar absorption due to photoinhibition, drought stress resulting from reduced precipitation and high evapotranspiration due to warmer temperatures, and minor effects of air pollution. The ARIM exemplifies a complex systems concept and methodology for evaluating multivariable factors in tree growth systems. ARIM provides a general model structure that incorporates complex direct and indirect interactions for tree system studies and quantitatively integrates knowledge and data from different disciplines by developing a new set of indices, the relative basis index values. The ARIM results implicate comprehensive habitat-dependent directions for long-term conservation policies and management of red spruce with environmental changes, climate change, and air pollution in the Great Smoky Mountains National Park.
Chloroplast DNA polymorphisms in eastern hemlock: range-wide genogeographic analyses and implications for gene conservation
Authors: Lemieux Michée Joseph , Beaulieu Jean , Bousquet Jean
Published: May 2011

The objective of this study was to determine if the genetic diversity of eastern hemlock ( Tsuga canadensis (L.) Carrière) is uniformly distributed or structured. Such information is relevant to help guide conservation efforts. Individuals were sampled in 60 range-wide populations of T. canadensis and genotyped at seven polymorphic chloroplast DNA loci. All 16 chlorotypes identified in T. canadensis were highly divergent from the unique chlorotype detected in Carolina hemlock ( Tsuga caroliniana Engelm.). Among-population differentiation in T. canadensis was low (GST = 0.020) and the distribution of chlorotypes did not show any strong geographical pattern, which is likely due to the homogenizing effect of pollen gene flow during the Holocene. Nevertheless, a spatial Bayesian approach revealed two distinct groups of populations. Furthermore, an analysis of relative genetic distances indicated that southeastern Appalachian populations harboured greater population differentiation while conserving relatively high allelic richness, which might represent the imprint of an ancient glacial refugium in the region. Thus, these distinctive genetic patterns and the risk of Tsuga decline following climate warming combined with the introduction of the insect Adelges tsugae (Annand) indicate that the southern part of the range should be considered of high priority for ex situ conservation.
Estimating forest biomass components with hemispherical photography for Douglas-fir stands in northwest Oregon
Authors: Clark Joshua , Murphy Glen
Published: May 2011

Accurately and quickly identifying inventories of forest biomass has become increasingly important for a variety of reasons. Current allometric equations require time-consuming tree-level measurements, but ground-based remote sensing could lead to faster estimates of forest biomass. Hemispherical photography (HP) is one potential technology that could estimate forest biomass quickly and efficiently. This analysis is based on a study in northwest Oregon where 15 Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) plots were destructively sampled, and 60 HPs (four per plot) were taken. One photograph was taken after removing each quartile of a plot (by basal area). Two subsets of bone-dry biomass were measured and estimated: (i) crown and branch biomass (CBB) and (ii) total aboveground biomass (AGB). AGB ranged from 136 to 423 Mg/ha, and CBB ranged from 26 to 68 Mg/ha. A regression analysis between actual and HP estimated biomass showed that the average of the top two and top three 18° zenith angles resulted in the highest correlation and lowest RMSE for both CBB and AGB, while an estimate of plant area index over the top three zenith angles had the lowest correlation. HP estimates are compared with two allometric equations: one based on a regional study and one based on a national compilation of studies.
Predicting long-term sapling dynamics and canopy recruitment in northern hardwood forests
Authors: Hanson Jacob J. , Lorimer Craig G. , Halpin Corey R.
Published: May 2011

Prediction of forest composition and structure over multiple generations of trees is often hampered by limited data on understory tree dynamics and the highly variable process of canopy recruitment in forest openings. In this paper, we describe a model of sapling dynamics and overstory recruitment for CANOPY, a spatially explicit, crown-based, individual-tree model of gap dynamics. The model incorporates gap size as a predictor of sapling recruitment and height growth, and it mimics the processes of sapling release, gap capture, and lateral gap closure. Calibration data were derived from 12 data sets with a wide range of stand ages and disturbance history in northern hardwood stands in the Great Lakes region, USA. The model accounted for 30%–62% of the variation in sapling density, composition, and growth rates. Predicted effects of increasing gap size on growth rate were similar to observed trends. Growth equations that included gap size as an independent variable generally gave better predictions of sapling density, species composition, and growth rates than equations based on conventional plot-level competition metrics. Long-term, 1000-year simulations produced estimates of stand basal areas and tree density in each size class that are close to the mean observed values for old-growth stands in the region.
Agricultural land-use history increases non-native plant invasion in a southern Appalachian forest a century after abandonment
Authors: Kuhman Timothy R. , Pearson Scott M. , Turner Monica G.
Published: May 2011

Land-use history can play a significant role in shaping forest communities. We considered the effects of agricultural land-use legacies on the distribution of non-native invasive plants a century after abandonment in a watershed in western North Carolina, USA. Forest sites that were previously in cultivation and abandoned ca. 1905 were compared with nearby reference sites that were never cultivated. The most common invasive plants were Celastrus orbiculatus Thunb., Microstegium vimineum Trin., and Lonicera japonica Thunb. Formerly cultivated sites and plots positioned downslope from roads had the most invasives. Soil cation concentration and pH were positively correlated with invasive presence and abundance. Historic agricultural plots where the successional tree Liriodendron tulipifera L. was dominant had the highest soil cation concentrations and soil pH and the greatest abundance of invasive plants. Disentangling the cause–effect relationships between land-use history, the biotic community, and the abiotic template presents a challenge, but understanding the role of land-use legacies may provide important insights regarding the mechanisms underlying the establishment and spread of invasive plants in forest ecosystems. Our results suggest that land-use history at Bent Creek may be facilitating plant invasion indirectly by causing a shift in overstory community composition that in turn creates more suitable understory conditions for shade-tolerant invasive plants.
Tree growth and disturbance dynamics in old-growth subalpine spruce forests of the Western Carpathians
Authors: Szewczyk Janusz , Szwagrzyk Jerzy , Muter Elżbieta
Published: May 2011

Are the dynamics of natural subalpine spruce ( Picea abies (L.) Karst.) forests of central Europe governed by stand-replacing disturbances caused mostly by winds or by moderate disturbances resulting from bark beetle outbreaks? We analyzed tree-ring series from subalpine spruce forests in two mountain ranges of the Western Carpathians to determine the frequency and severity of disturbances and their effects on tree recruitment. The boundary-line method was employed to identify significant growth releases, interpreted as results of disturbances. In both study areas, major releases were not numerous but were regularly distributed over time. We found no evidence for stand-replacing disturbances. This result contrasts sharply with earlier findings from the Western Carpathians. The age structure of the forests studied indicates that the amount of tree recruitment was greater 150–200 years ago than in the subsequent 150 years. Our results suggest that stand dynamics in the forests analyzed are driven by numerous events of limited spatial extent and that stand-replacing disturbances are not necessary for the development of unimodal age structure.
Detection of high-wind events using tree-ring data
Authors: Hadley Keith S. , Knapp Paul A.
Published: May 2011

Windstorms are common events in midlatitude west coast climates yet little is known about their long-term history and influence on regional forests. In this paper, we present a procedure that detects the timing and frequency of these high-wind events (HWEs) along the Pacific Northwest coast of North America using crossdated tree-ring measurements and detrended tree-ring chronologies derived from windsnapped trees. Our results show that abrupt changes in ring width patterns closely match dates of known HWEs and can serve as a nonclimatic basis for crossdating. Experimentation with different growth suppression and release criteria revealed that either a 50% decrease or a 50% increase in radial growth relative to the mean index value provided the best criterion for detecting windstorm-related growth anomalies. Comparing these results with the known occurrence of windstorms during the past century successfully identified all known major wind events during the study period. Low correlations between tree growth and climatic variables further imply that HWEs are the principal cause of interannual growth variations. Accordingly, we discuss the application of our procedure toward the development of a multicentury reconstruction of HWEs, a long-term analysis of decadal climate variability and HWEs, and the ecological role of HWEs in Pacific Northwest and other west coast forests.
Amelioration of doxorubicin-induced cardiotoxicity by deferiprone in rats
Authors: Ammar El-Sayed M. , Said Shehta A. , Suddek Ghada M. , El-Damarawy Sally L.
Published: May 2011

The therapeutic usefulness of doxorubicin (Dox), an anthracycline antibiotic used as an anticancer agent, is limited by its cardiotoxicity. Dox-induced cardiotoxicity is mainly attributed to accumulation of reactive oxygen species and interaction of Dox with cellular iron metabolism. The present study investigated the effects of the iron chelator deferiprone (Def) against Dox-induced cardiotoxicity in rats. Dox (15 mg/kg) was injected intraperitoneally as a single dose, and Def (10 mg/kg) was administered orally for 10 days. Dox showed cardiotoxicity as evidenced by increased heart rate, elevated ST segment, prolonged QTc interval, and increased T wave amplitude. In addition, Dox enhanced aconitine cardiotoxicity by decreasing its dose, producing ventricular tachycardia. Administration of Def significantly attenuated Dox-induced electrocardiographic changes. Cardiotoxicity of Dox was confirmed biochemically by a significant elevation in serum creatine kinase-MB and lactate dehydrogenase activities as well as by myocardial malondialdehyde and reduced glutathione contents. Moreover, Dox caused a significant decrease in myocardial superoxide dismutase activity. Administration of Def significantly attenuated the biochemical changes. These results suggest that Def might be a potential cardioprotective agent against Dox-induced cardiotoxicity.
Orchidectomy attenuates impaired endothelial effects of a high-salt diet in Sprague–Dawley rats
Authors: Oloyo A.K. , Sofola O.A. , Anigbogu C.N.
Published: May 2011

The effect of sex hormones on vascular reactivity is considered one of the underlying factors contributing to gender differences in cardiovascular functions and diseases. Experiments were designed to investigate the role of androgens in salt-induced hypertension by assessing the relaxation response of isolated aortic rings to acetylcholine and sodium nitroprusside in the presence or absence of l-nitroarginine methyl ester in Sprague–Dawley rats. The rats were either orchidectomized or sham-operated, with or without testosterone replacement, and were placed on a normal or high-salt diet for 6 weeks. The results indicate a significant increase (p < 0.001) in the mean arterial blood pressure of rats on the high-salt diet, when compared with control or orchidectomized rats. Orchidectomy elicited a reduction in mean arterial blood pressure (p < 0.01), while testosterone replacement normalized mean arterial blood pressure to values seen in intact rats on the high-salt diet. The high-salt diet reduced the relaxation response to acetylcholine both in the presence and absence of inhibition of endothelial nitric oxide synthase with l-nitroarginine methyl ester. Bilateral orchidectomy attenuated the impaired endothelial function induced by the high-salt diet in rats, but this was reversed by concomitant administration of testosterone, suggesting a role for androgens in enhancing long-term vascular smooth muscle tone and hence maintenance of high blood pressure in salt-induced hypertension.
TRAVEL TIME DISTRIBUTION FOR NETWORK FLOWS UNDER LOCAL ROUTING
Authors: WANG CHAO-YANG , GAO ZI-YOU , ZHENG JIAN-FENG , DAI SHUAI
Published: May 2011

When transporting data packets on communication networks, the local routing protocols are often preferred because of the large-scale and complicated property of many realistic network structures such as Internet. Based on a local routing protocol with a navigation parameter proposed in a previous paper [W. X. Wang et al., Phys. Rev. E73, 026111 (2006)], this paper numerically investigates the distribution of travel time for transporting data packets from the origin to the destination in complex networks, including random networks, small-world networks and scale-free networks. Numerical results show that exponential distributions of travel time with various values of exponent in complex networks are obtained. Furthermore, the different values of the exponent can also intuitively prove the previous result for the optimal local routing strategy. Finally, violations of the First-Departure-First-Arrival situation in complex networks are discussed.
RHEOLOGY OF NOVEL FERROFLUIDS
Authors: BORIN DMITRY , ODENBACH STEFAN
Published: May 2011

The progress in the synthesis of new magnetic nanoparticles and agglomerates stimulates the development of novel ferrofluids with enhanced rheological properties. In the current work ferrofluids based on Co-nanoplatelets and clustered iron oxide nanoparticles have been considered. Steady-shear experiments and yield stress measurements of these ferrofluids have been performed using rotational rheometry.
GRAVITATIONAL COLLAPSE WITH TANGENTIAL PRESSURE
Authors: MALAFARINA DANIELE , JOSHI PANKAJ S.
Published: May 2011

Using the general formalism for spherical gravitational collapse developed in [P. S. Joshi and I. H. Dwivedi, Class. Quant. Grav.16 (1999) 41; P. S. Joshi and R. Goswami, Phys. Rev. D76 (2007) 084026], we investigate here the final fate of a spherical distribution of a matter cloud, where radial pressures vanish but tangential pressures are nonzero. Within this framework, firstly we examine the effect of introducing a generic small pressure in a well-known black hole formation process, which is that of an otherwise pressure-free dust cloud. The intriguing result we find is that a dust collapse that was going to a black hole final state could now go to a naked singularity final configuration, when arbitrarily small tangential pressures are introduced. The implications of such a scenario are discussed in some detail. Secondly, the approach here allows us to generalize the earlier results obtained on gravitational collapse with nonzero tangential pressure, in the presence of a nonzero cosmological constant. Finally, we discuss the genericity of black hole and naked singularity formation in collapse with nonzero tangential pressure. The treatment here gives a unified and complete picture on collapse final states, in terms of black hole and naked singularity formation, generalizing the earlier results obtained for this class of collapse models. Thus the role of tangential stresses towards determining collapse end-states emerges in a straightforward and transparent manner in our treatment.
3D FRACTAL DIMENSION AND FLOW PROPERTIES IN THE PORE STRUCTURE OF GEOLOGICAL ROCKS
Authors: FERANIE SELLY , FAUZI UMAR , BIJAKSANA SATRIA
Published: May 2011

Three-dimensional pore structure of four samples of geological rock was obtained using serial sectioning. Their fractal and flow properties have been successfully determined through image analysis. The measured 3D box counting fractal dimension of four geological rock samples are 2.59, 2.88, 2.88 and 2.29, which are not integer dimensions. This would imply that the structure of the four geological rock samples is fractal in nature. Porosity of the four rock samples are ranged from 0.18 to 0.31 and the specific surface area is ranged from 1.57 to 2.75 mm-1. Tortuosity estimated from image analysis of the four samples is ranged from 1.11 to 5.83 and varied in each fluid flow direction. This would imply that the rock samples are not uniform in its pore structure. The fractal dimension as a representation of the isotropic level of the pore structure is not clearly clarified and it still needs further investigation.
DOUBLE BARRIER OPTIONS IN REGIME-SWITCHING HYPER-EXPONENTIAL JUMP-DIFFUSION MODELS
Authors: BOYARCHENKO MITYA , BOYARCHENKO SVETLANA
Published: May 2011

We present a very fast and accurate algorithm for calculating prices of finite lived double barrier options with arbitrary terminal payoff functions under regime-switching hyper-exponential jump-diffusion (HEJD) models, which generalize the double-exponential jump-diffusion model pioneered by Kou and Lipton. Numerical tests demonstrate an excellent agreement of our results with those obtained using other methods, as well as a significant increase in computation speed (sometimes by a factor of 5). The first step of our approach is Carr's randomization, whose convergence we prove for barrier and double barrier options under strong Markov processes of a wide class. The resulting sequence of perpetual option pricing problems is solved using an efficient iteration algorithm and the Wiener-Hopf factorization.
VOLATILITY DERIVATIVES IN MARKET MODELS WITH JUMPS
Authors: LO HARRY , MIJATOVIĆ ALEKSANDAR
Published: May 2011

It is well documented that a model for the underlying asset price process that seeks to capture the behaviour of the market prices of vanilla options needs to exhibit both diffusion and jump features. In this paper we assume that the asset price process S is Markov with càdlàg paths and propose a scheme for computing the law of the realized variance of the log returns accrued while the asset was trading in a prespecified corridor. We thus obtain an algorithm for pricing and hedging volatility derivatives and derivatives on the corridor-realized variance in such a market. The class of models under consideration is large, as it encompasses jump-diffusion and Lévy processes. We prove the weak convergence of the scheme and describe in detail the implementation of the algorithm in the characteristic cases where S is a CEV process (continuous trajectories), a variance gamma process (jumps with independent increments) or an infinite activity jump-diffusion (discontinuous trajectories with dependent increments).
ELECTROMYOGRAPHY (EMG) SIGNAL CLASSIFICATION BASED ON DETRENDED FLUCTUATION ANALYSIS
Authors: PHINYOMARK ANGKOON , PHUKPATTARANONT PORNCHAI , LIMSAKUL CHUSAK , PHOTHISONOTHAI MONTRI
Published: May 2011

Electromyography (EMG) signal is a useful signal in various medical and engineering applications. To extract the useful information in the EMG signal, feature extraction method should be performed. The extracted features of the EMG signal are usually calculated based on linear or statistical methods, but the EMG signal exhibits the nonlinear and more complex in the properties. With recent advances in nonlinear analysis we are proposing the study of the EMG signals from upper-limb movements using Detrended Fluctuation Analysis (DFA) method. This study used EMG signals obtained from eight upper-limb movements and five muscle positions as representative EMG signals. The usefulness of the DFA method has been proposed to discriminate the upper-limb movements. Complete comparative studies of an optimal parameter of the DFA method were performed. From the viewpoints of maximum class separability, robustness, and complexity, scaling exponent obtained from the DFA method shows the appropriateness to be used as a feature in the classification of the EMG signal. From the experimental results, an optimal DFA method is obtained under these conditions: the minimum box size is approximately four, the maximum box size is one-tenth of the signal length, the box size increment is based on a power of two, and the quadratic polynomial fits is used in the fitting procedure. Moreover, the classification performance of the DFA method is better than other existing nonlinear methods, including the Higuchi's method.
GENERALIZED SOLUTIONS OF THE CAUCHY PROBLEM FOR SYSTEMS OF NONLINEAR PARABOLIC EQUATIONS AND DIFFUSION PROCESSES
Authors: BELOPOLSKAYA YANA , WOYCZYNSKI WOJBOR A.
Published: May 2011

The purpose of this paper is to construct both strong and weak solutions (in certain functional classes) of the Cauchy problem for a class of systems of nonlinear parabolic equations via a unified stochastic approach. To this end we give a stochastic interpretation of such a system, treating it as a version of the backward Kolmogorov equation for a two-component Markov process with coefficients depending on the distribution of its first component. To extend this approach and apply it to the construction of a generalized solution of a system of nonlinear parabolic equations, we use results from Kunita's theory of stochastic flows.
RANDOM WALKS WITH HEAVY TAILS AND LIMIT THEOREMS FOR BRANCHING PROCESSES WITH MIGRATION AND IMMIGRATION
Authors: FENG YAQIN , MOLCHANOV STANISLAV , WHITMEYER JOSEPH
Published: May 2011

The central result of this paper is the existence of limiting distributions for two classes of critical homogeneous-in-space branching processes with heavy tails spatial dynamics in dimension d = 2. In dimension d ≥ 3, the same results are true without any special assumptions on the underlying (non-degenerated) stochastic dynamics.
THE SYNTHESIS OFTiO2NANOPARTICLES BY WET-CHEMICAL METHOD AND THEIR PHOTOLUMINESCENCE, THERMAL AND VIBRATIONAL CHARACTERIZATIONS: EFFECT OF GROWTH CONDITION
Authors: DESAI RUCHA , GUPTA SANJEEV K. , MISHRA SHREE , JHA P. K. , PRATAP A.
Published: May 2011

Low temperature calcination methods have been developed to obtain anatase TiO2nanocrystals using three different synthesis routes. The DSC thermograms have been used to set the annealing temperature. Various size of TiO2nanocrystals ranging from 8 nm to 16.5 nm have been used to synthesize by setting up the annealing temperature and time. The X-ray diffraction (XRD) and Raman spectrum have been used to identify and confirm the anatase crystal structure having long range ordering. The photoluminescence (PL) spectra have been recorded as a function of particle size and excitation power, which is attributed to the defects inside the grain that can migrate into the grain surface region during annealing. In a typical TiO2nanocrystals (sample TN12), luminescence efficiency increases with the decrease in size due to e-/ h+recombination process.
GAUGE GROUP AND TOPOLOGY CHANGE
Authors: TANAKA IZUMI , NAGAMI SEIJI
Published: May 2011

The purpose of this study is to examine the effect of topology change in the initial universe. In this study, the concept of G-cobordism is introduced to argue about the topology change of the manifold on which a transformation group acts. This G-manifold has a fiber bundle structure if the group action is free and is related to the spacetime in Kaluza–Klein theory or Einstein–Yang–Mills system. Our results revealed the fundamental processes of compactification in G-manifolds. In these processes, the initial high symmetry and multidimensional universe changes to present universe by the mechanism which lowers the dimensions and symmetries.
ON A PROBLEM OF GEOMETRIC QUANTIZATION
Authors: HEDREA CIPRIAN , NEGREA ROMEO , ZAHARIE IOAN , PUTA MIRCEA
Published: May 2011

The problem of geometric Kostant quantization of this paper is the role played by "½-correction forms" in order to arrive at the result given by the classical Schrödinger quantization, in the one-dimensional harmonic oscillator study.
ON ELECTRICAL CORRELATES OF PHYSARUM POLYCEPHALUM SPATIAL ACTIVITY: CAN WE SEE PHYSARUM MACHINE IN THE DARK?
Authors: ADAMATZKY ANDREW , JONES JEFF
Published: May 2011

Plasmodium of Physarum polycephalum is a single cell visible by unaided eye, which spans sources of nutrients with its protoplasmic network. In a very simple experimental setup we recorded electric potential of the propagating plasmodium. We discovered a complex interplay of short range oscillatory behavior combined with long range, low frequency oscillations which serve to communicate information between different parts of the plasmodium. The plasmodium's response to changing environmental conditions forms basis patterns of electric activity, which are unique indicators of the following events: plasmodium occupies a site, plasmodium functions normally, plasmodium becomes "agitated" due to drying substrate, plasmodium departs a site, and plasmodium forms sclerotium. Using a collective particle approximation of Physarum polycephalum we found matching correlates of electrical potential in computational simulations by measuring local population flux at the node positions, generating trains of high and low frequency oscillatory behavior. Motifs present in these measurements matched the response "grammar" of the plasmodium when encountering new nodes, simulated consumption of nutrients, exposure to simulated hazardous illumination and sclerotium formation. The distributed computation of the particle collective was able to calculate beneficial network structures and sclerotium position by shifting the active growth zone of the simulated plasmodium. The results show future promise for the non-invasive study of the complex dynamical behavior within — and health status of — living systems.
Impact of random failures and attacks on Poisson and power-law random networks
Authors: Magnien Clémence , Latapy Matthieu , Guillaume Jean-Loup
Published: May 2011

It has appeared recently that the underlying degree distribution of networks may play a crucial role concerning their robustness. Previous work insisted on the fact that power-law degree distributions induce high resilience to random failures but high sensitivity to attack strategies, while Poisson degree distributions are quite sensitive in both cases. Then much work has been done to extend these results.

We aim here at studying in depth these results, their origin, and limitations. We review in detail previous contributions in a unified framework, and identify the approximations on which these results rely. We then present new results aimed at clarifying some important aspects. We also provide extensive rigorous experiments which help evaluate the relevance of the analytic results.

We reach the conclusion that, even if the basic results are clearly important, they are in practice much less striking than generally thought. The differences between random failures and attacks are not so huge and can be explained with simple facts. Likewise, the differences in the behaviors induced by power-law and Poisson distributions are not as striking as often claimed.
Machine transliteration survey
Authors: Karimi Sarvnaz , Scholer Falk , Turpin Andrew
Published: May 2011

Machine transliteration is the process of automatically transforming the script of a word from a source language to a target language, while preserving pronunciation. The development of algorithms specifically for machine transliteration began over a decade ago based on the phonetics of source and target languages, followed by approaches using statistical and language-specific methods. In this survey, we review the key methodologies introduced in the transliteration literature. The approaches are categorized based on the resources and algorithms used, and the effectiveness is compared.
Implementing statically typed object-oriented programming languages
Authors: Ducournau Roland
Published: May 2011

Object-oriented programming represents an original implementation issue due to its philosophy of making the program behavior depend on the dynamic type of objects. This is expressed by the
late binding
mechanism, aka
message sending
. The underlying principle is that the address of the actually called procedure is not statically determined at compile-time, but depends on the dynamic type of a distinguished parameter known as the
receiver
. A similar issue arises with attributes, because their position in the object layout may also depend on the object's dynamic type. Furthermore, subtyping introduces another original feature (i.e., runtime subtype checks). All three mechanisms need specific implementations and data structures. In static typing, late binding is generally implemented with so-called
virtual function tables
. These tables reduce method calls to pointers to functions via a small fixed number of extra indirections. It follows that object-oriented programming yields some overhead, as compared to the usual procedural languages.

The different techniques and their resulting overhead depend on several parameters. First, inheritance and subtyping may be single or multiple, and even a mixing is possible, as in Java and ˙NET which present single inheritance for classes and multiple subtyping for interfaces. Multiple inheritance is a well-known complication. Second, the production of executable programs may involve various schemes, from global compilation, which implies the
closed-world assumption
(CWA), as the whole program is known at compile time, to separate compilation and dynamic loading, where each program unit is compiled and loaded independently of any usage, hence under the
open-world assumption
(OWA). Global compilation is well-known to facilitate optimization.

This article reviews the various implementation techniques available in static typing and in the three cases of single inheritance, multiple inheritance, and multiple subtyping. This language-independent survey focuses on separate compilation and dynamic loading, as they represent the most commonly used and the most demanding framework. However, many works have been undertaken in the global compilation framework, mostly for dynamically typed languages, but also applied to the EIFFEL language. Hence, we also examine global techniques and how they can improve implementation efficiency. Finally, mixed frameworks that combine open and closed world assumptions are considered. For instance, just-in-time (JIT) compilers work under provisional CWA, at the expense of possible recompilations. In contrast, we present an experimental compiler-linker, where separate compilation implies the OWA, whereas the whole program is finally linked under the CWA.