bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuronal circuits in the hypothalamus controlling gonadotrophin‐releasing hormone release: the neuroanatomical projections of kisspeptin neurons
Authors: Yeo Shel‐Hwa
Published: August 2013

New findings

What is the topic of this review?

Kisspeptin neurons have been implicated as important regulators of mammalian reproduction and fertility. This study aimed to investigate the axonal projections of kisspeptin neurons in adult female mouse brain using classical neuroanatomical tracers.

What advances does it highlight?

The tracing results revealed the innervation patterns of kisspeptin neurons in the arcuate nucleus and rostral periventricular area of the third ventricle. These projections highlighted the diversity of brain regions possibly targeted by kisspeptin neurons, suggesting their involvement in the regulation of multiple circuits in addition to the gonadotrophin‐releasing hormone neuronal network. The present study provides a neuroanatomical framework for the further elucidation of the functions of the kisspeptin neuron populations in the arcuate nucleus and rostral periventricular area of the third ventricle.

The hypothalamus regulates the key hormonal signalling events essential for reproduction and fertility in mammals. The gonadotrophin‐releasing hormone (GnRH) neurons are the principal neurons of the complex neuronal network that co‐ordinates multiple internal homeostatic and external factors necessary for fertility. Kisspeptin neurons are one of the major regulators of GnRH neuronal activity, but the ways in which kisspeptin neurons, located in the arcuate nucleus (ARN) and rostral periventricular area of the third ventricle (RP3V), control GnRH neurons are poorly understood. This study focused on the use of anterograde and retrograde tracing techniques to establish the neuronal projection patterns of kisspeptin cells in the female mouse brain. Both anterograde and retrograde tracing studies highlight the complexity of the kisspeptin neuronal system and indicate that both ARN and RP3V kisspeptin neurons may participate in a variety of limbic functions. In relationship to the GnRH neuronal network, these investigations demonstrate that rostral ARN kisspeptin neurons may also project to GnRH neuronal cell bodies. However, we found no anatomical evidence to suggest that kisspeptin neurons innervate GnRH nerve terminals in the external layer of the median eminence. These studies provide a neuroanatomical framework for the further elucidation of the functions of the ARN and RP3V kisspeptin neuron populations.
Modular Advantage and Kinematic Decoupling in Gravity Compensated Robotic Systems
Authors: Eckenstein Nick , Yim Mark
Published: August 2013

Two new designs for gravity compensated modular robotic systems are presented and analyzed. The gravity compensation relies on using zero-free-length springs approximated by a cable and pulley system. Simple yet powerful parallel four-bar modules enable the low-profile self-contained modules with sequential gravity compensation using the spring method for motion in a vertical plane. A second module that is formed as a parallel six-bar mechanism adds a horizontal motion to the previous system that also yields a complete decoupling of position and orientation of the distal end of a serial chain. Additionally, we introduce the concept of vanishing effort where as the number of modules that comprise an articulated serial chain increases, the actuation authority required at any joint reduces. Essentially, this results in a method for distributing actuation along the length of an articulated chain. Prototypes were designed and constructed validating the analysis and accomplishing the functions of a general serial-type manipulator arm.
Effect of Tube Location Change on Heat Transfer Characteristics of Plain Plate Fin-and-Tube Heat Exchangers
Authors: Yin Jixiang , He Zeming , Chen Fuqiang , Ma Jianzong
Published: August 2013

Three-dimensional numerical simulations are conducted for the air-side steady laminar flow and heat transfer characteristics of the plate fin-and-tube heat exchanger element. The effects of Reynolds number (Re), tube center location (Lc/D), and fin pitch (H/D) are examined. The Re based on the tube diameter and the air inlet velocity varies from 100 to 5000, the tube center location from 0.75 to 2, and the fin pitch from 0.2 to 0.5. The numerical results show that the increase of Re leads to the increase of heat transfer parameters (such as the span-averaged Nu¯(x), the overall average Nusselt number (Nu¯f, Nu¯f,t) of the fin as well as fin-and-tube, the fin surface average heat bulk q¯) and the averaged pressure drop on cross-sectional P¯(x), and the decrease of the friction factor (f) and the fin efficiency (ηf); moreover, the larger Re is, the smaller the influence on these parameters except the P¯(x). Regarding the effect of tube location (Lc/D), the f is almost insensitive to the Lc/D change, and the overall average Nusselt numbers of the fin as well as fin-and-tube increase with increasing Lc/D, but the q¯ and the ηf first gradually increase and then decrease. And so consequently, there exist the optimum Lc/D values corresponding to the largest averaged q¯ on the fin surface and the largest ηf, respectively. The investigation ascertains that the region achieving the highest average Nu¯(x) is not always holding the largest q¯(x) and/or the largest ηf for a conjugate heat transfer problem. The H/D has a positive impact on the ηf, namely the larger the H/D, the higher the ηf.
Automatic quantification of epicardial fat volume on non‐enhanced cardiac CT scans using a multi‐atlas segmentation approach
Authors: Shahzad Rahil , Bos Daniel , Metz Coert , Rossi Alexia , Kirişli Hortense , van der Lugt Aad , Klein Stefan , Witteman Jacqueline , de Feyter Pim , Niessen Wiro , van Vliet Lucas , van Walsum Theo
Published: August 2013

Purpose:

There is increasing evidence that epicardial fat (i.e., adipose tissue contained within the pericardium) plays an important role in the development of cardiovascular disease. Obtaining the epicardial fat volume from routinely performed non‐enhanced cardiac CT scans is therefore of clinical interest. The purpose of this work is to investigate the feasibility of automatic pericardium segmentation and subsequent quantification of epicardial fat on non‐enhanced cardiac CT scans.

Methods:

Imaging data of 98 randomly selected subjects belonging to a larger cohort of subjects who underwent a cardiac CT scan at our medical center were retrieved. The data were acquired on two different scanners. Automatic multi‐atlas based method for segmenting the pericardium and calculating the epicardial fat volume has been developed. The performance of the method was assessed by (1) comparing the automatically segmented pericardium to a manually annotated reference standard, (2) comparing the automatically obtained epicardial fat volumes to those obtained manually, and (3) comparing the accuracy of the automatic results to the inter‐observer variability.

Results:

Automatic segmentation of the pericardium was achieved with a Dice similarity index of 89.1 ± 2.6% with respect to Observer 1 and 89.2 ± 1.9% with respect to Observer 2. The correlation between the automatic method and the manual observers with respect to the epicardial fat volume computed as the Pearson's correlation coefficient (R) was 0.91 (P < 0.001) for both observers. The inter‐observer study resulted in a Dice similarity index of 89.0 ± 2.4% for segmenting the pericardium and a Pearson's correlation coefficient of 0.92 (P < 0.001) for computation of the epicardial fat volume.

Conclusions:

The authors developed a fully automatic method that is capable of segmenting the pericardium and quantifying epicardial fat on non‐enhanced cardiac CT scans. The authors demonstrated the feasibility of using this method to replace manual annotations by showing that the automatic method performs as good as manual annotation on a large dataset.
Mercury Methylation by the Methanogen Methanospirillum hungatei
Authors: Yu Ri-Qing , Reinfelder John R. , Hines Mark E. , Barkay Tamar
Published: August 2013

Methylmercury (MeHg), a neurotoxic substance that accumulates in aquatic food chains and poses a risk to human health, is synthesized by anaerobic microorganisms in the environment. To date, mercury (Hg) methylation has been attributed to sulfate- and iron-reducing bacteria (SRB and IRB, respectively). Here we report that a methanogen,
Methanospirillum hungatei
JF-1, methylated Hg in a sulfide-free medium at comparable rates, but with higher yields, than those observed for some SRB and IRB. Phylogenetic analyses showed that the concatenated orthologs of the Hg methylation proteins HgcA and HgcB from
M. hungatei
are closely related to those from known SRB and IRB methylators and that they cluster together with proteins from eight other methanogens, suggesting that these methanogens may also methylate Hg. Because all nine methanogens with HgcA and HgcB orthologs belong to the class
Methanomicrobia
, constituting the late-evolving methanogenic lineage, methanogenic Hg methylation could not be considered an ancient metabolic trait. Our results identify methanogens as a new guild of Hg-methylating microbes with a potentially important role in mineral-poor (sulfate- and iron-limited) anoxic freshwater environments.
Novel Cultivation-Based Approach To Understanding the Miscellaneous Crenarchaeotic Group (MCG) Archaea from Sedimentary Ecosystems
Authors: Gagen Emma J. , Huber Harald , Meador Travis , Hinrichs Kai-Uwe , Thomm Michael
Published: August 2013

The uncultured miscellaneous crenarchaeotic group (MCG) archaea comprise one of the most abundant microbial groups in the Earth's subsurface environment. However, very little information is available regarding the lifestyle, physiology, and factors controlling the distribution of members of this group. We established a novel method using both cultivation and molecular techniques, including a pre-PCR propidium monoazide treatment, to investigate viable members of the MCG
in vitro
. Enrichment cultures prepared from estuarine sediment were provided with one of a variety of carbon substrates or cultivation conditions and incubated for 3 weeks. Compared with the samples from time zero, there was an order-of-magnitude increase in the number of MCG 16S rRNA genes in almost all cultures, indicating that MCG archaea are amenable to
in vitro
cultivation. None of the tested substrates or conditions significantly stimulated growth of MCG archaea more than the basal medium alone; however, glycerol (0.02%) had a significantly inhibitory effect (
P
< 0.05). Diversity analysis of populations resulting from four culture treatments (basal medium, addition of amino acids, H
2
-CO
2
as the gas phase, or initial aerobic conditions) revealed that the majority of viable MCG archaea were affiliated with the MCG-8 and MCG-4 clusters. There were no significant differences in MCG diversity between these treatments, also indicating that some members of MCG-4 and MCG-8 are tolerant of initially oxic conditions. The methods outlined here will be useful for further investigation of MCG archaea and comparison of substrates and cultivation conditions that influence their growth
in vitro
.
Functional Identification of Rubber Oxygenase (RoxA) in Soil and Marine Myxobacteria
Authors: Birke Jakob , Röther Wolf , Schmitt Georg , Jendrossek Dieter
Published: August 2013

The rubber oxygenase (RoxA) of
Xanthomonas
sp. strain 35Y (RoxA

Xsp

) is so far the only known extracellular
c
-type diheme cytochrome that is able to cleave poly(
cis
-1,4-isoprene). All other rubber-degrading bacteria described are Gram positive and employ a nonheme protein (latex-clearing protein [Lcp]) for the postulated primary attack of polyisoprene. Here, we identified RoxA orthologs in the genomes of
Haliangium ochraceum
,
Myxococcus fulvus
,
Corallococcus coralloides
, and
Chondromyces apiculatus
. The
roxA
orthologs of
H. ochraceum
(RoxA

Hoc

),
C. coralloides
BO35 (RoxA

Cco

), and
M. fulvus
(RoxA

Mfu

) were functionally expressed in a Δ
roxA Xanthomonas
sp. 35Y background. All RoxA orthologs oxidatively cleaved polyisoprene, as revealed by restoration of clearing-zone formation and detection of 12-oxo-4,8-dimethyltrideca-4,8-diene-1-al (ODTD) as a cleavage product. RoxA

Xsp

, RoxA

Mfu

, and RoxA

Cco

were purified and biochemically characterized. The optimal temperature of RoxA

Cco

and RoxA

Mfu

was between 22 and 30°C. All RoxA orthologs as isolated showed an oxidized UV-visible spectrum. Chemical reduction of RoxA

Cco

and RoxA

Mfu

indicated the presence of two slightly different heme centers with absorption maxima between 549 and 553 nm, similar to RoxA

Xsp

. Sequence analysis and modeling of the three-dimensional structures of the RoxA orthologs revealed a high degree of similarity to the recently solved RoxA

Xsp

structure and included several conserved residues, notably, W
302
, F
317
, and a MauG motif at about H
517
. Lcp-like sequences were not detected in the genomes of the
Xanthomonas
sp. 35Y,
H. ochraceum
,
M. fulvus
, and
C. coralloides
. No RoxA orthologs were found in Gram-positive bacteria, and this first description of functional RoxA in Gram-negative bacteria other than
Xanthomonas
proves that RoxA is more common among rubber degraders than was previously assumed.
Comparative Genomic and Transcriptomic Analyses Reveal Habitat Differentiation and Different Transcriptional Responses during Pectin Metabolism in Alishewanella Species
Authors: Jung Jaejoon , Park Woojun
Published: August 2013

Alishewanella
species are expected to have high adaptability to diverse environments because they are isolated from different natural habitats. To investigate how the evolutionary history of
Alishewanella
species is reflected in their genomes, we performed comparative genomic and transcriptomic analyses of
A. jeotgali
,
A. aestuarii
, and
A. agri
, which were isolated from fermented seafood, tidal flat sediment, and soil, respectively. Genomic islands with variable GC contents indicated that invasion of prophage and transposition events occurred in
A. jeotgali
and
A. agri
but not in
A. aestuarii
. Habitat differentiation of
A. agri
from a marine environment to a terrestrial environment was proposed because the species-specific genes of
A. agri
were similar to those of soil bacteria, whereas those of
A. jeotgali
and
A. aestuarii
were more closely related to marine bacteria. Comparative transcriptomic analysis with pectin as a sole carbon source revealed different transcriptional responses in
Alishewanella
species, especially in oxidative stress-, methylglyoxal detoxification-, membrane maintenance-, and protease/chaperone activity-related genes. Transcriptomic and experimental data demonstrated that
A. agri
had a higher pectin degradation rate and more resistance to oxidative stress under pectin-amended conditions than the other 2
Alishewanella
species. However, expression patterns of genes in the pectin metabolic pathway and of glyoxylate bypass genes were similar among all 3
Alishewanella
species. Our comparative genomic and transcriptomic data revealed that
Alishewanella
species have evolved through horizontal gene transfer and habitat differentiation and that pectin degradation pathways in
Alishewanella
species are highly conserved, although stress responses of each
Alishewanella
species differed under pectin culture conditions.
Mapping of the SecA Signal Peptide Binding Site and Dimeric Interface by Using the Substituted Cysteine Accessibility Method
Authors: Bhanu Meera K. , Zhao Ping , Kendall Debra A.
Published: August 2013

SecA is an ATPase nanomotor critical for bacterial secretory protein translocation. Secretory proteins carry an amino-terminal signal peptide that is recognized and bound by SecA followed by its transfer across the SecYEG translocon. While this process is crucial for the onset of translocation, exactly where the signal peptide interacts with SecA is unclear. SecA protomers also interact among themselves to form dimers in solution, yet the oligomeric interface and the residues involved in dimerization are unknown. To address these issues, we utilized the substituted cysteine accessibility method (SCAM); we generated a library of 23 monocysteine SecA mutants and probed for the accessibility of each mutant cysteine to maleimide-(polyethylene glycol)
2
-biotin (MPB), a sulfhydryl-labeling reagent, both in the presence and absence of a signal peptide. Dramatic differences in MPB labeling were observed, with a select few mutants located at the preprotein cross-linking domain (PPXD), the helical wing domain (HWD), and the helical scaffold domain (HSD), indicating that the signal peptide binds at the groove formed between these three domains. The exposure of this binding site is varied under different conditions and could therefore provide an ideal mechanism for preprotein transfer into the translocon. We also identified residues G793, A795, K797, and D798 located at the two-helix finger of the HSD to be involved in dimerization. Adenosine-5′-(γ-thio)-triphosphate (ATPγS) alone and, more extensively, in conjunction with lipids and signal peptides strongly favored dimer dissociation, while ADP supports dimerization. This study provides key insight into the structure-function relationships of SecA preprotein binding and dimer dissociation.
Characterization of IntA, a Bidirectional Site-Specific Recombinase Required for Conjugative Transfer of the Symbiotic Plasmid of Rhizobium etli CFN42
Authors: Hernández-Tamayo Rogelio , Sohlenkamp Christian , Puente José Luis , Brom Susana , Romero David
Published: August 2013

Site-specific recombination occurs at short specific sequences, mediated by the cognate recombinases. IntA is a recombinase from
Rhizobium etli
CFN42 and belongs to the tyrosine recombinase family. It allows cointegration of plasmid p42a and the symbiotic plasmid via site-specific recombination between attachment regions (
attA
and
attD
) located in each replicon. Cointegration is needed for conjugative transfer of the symbiotic plasmid. To characterize this system, two plasmids harboring the corresponding attachment sites and
intA
were constructed. Introduction of these plasmids into
R. etli
revealed IntA-dependent recombination events occurring at high frequency. Interestingly, IntA promotes not only integration, but also excision events, albeit at a lower frequency. Thus,
R. etli
IntA appears to be a bidirectional recombinase. IntA was purified and used to set up electrophoretic mobility shift assays with linear fragments containing
attA
and
attD
. IntA-dependent retarded complexes were observed only with fragments containing either
attA
or
attD
. Specific retarded complexes, as well as normal
in vivo
recombination abilities, were seen even in derivatives harboring only a minimal attachment region (comprising the 5-bp central region flanked by 9- to 11-bp inverted repeats). DNase I-footprinting assays with IntA revealed specific protection of these zones. Mutations that disrupt the integrity of the 9- to 11-bp inverted repeats abolish both specific binding and recombination ability, while mutations in the 5-bp central region severely reduce both binding and recombination. These results show that IntA is a bidirectional recombinase that binds to
att
regions without requiring neighboring sequences as enhancers of recombination.
Structure-Function Analysis of MurJ Reveals a Solvent-Exposed Cavity Containing Residues Essential for Peptidoglycan Biogenesis in Escherichia coli
Authors: Butler Emily K. , Davis Rebecca M. , Bari Vase , Nicholson Paul A. , Ruiz Natividad
Published: August 2013

Gram-negative bacteria such as
Escherichia coli
build a peptidoglycan (PG) cell wall in their periplasm using the precursor known as lipid II. Lipid II is a large amphipathic molecule composed of undecaprenyl diphosphate and a disaccharide-pentapeptide that PG-synthesizing enzymes use to build the PG sacculus. During PG biosynthesis, lipid II is synthesized at the cytoplasmic face of the inner membrane and then flipped across the membrane. This translocation of lipid II must be assisted by flippases thought to shield the disaccharide-pentapeptide as it crosses the hydrophobic core of the membrane. The inner membrane protein MurJ is essential for PG biogenesis and homologous to known and putative flippases of the MOP (
m
ultidrug/
o
ligo-saccharidyl-lipid/
p
olysaccharide) exporter superfamily, which includes flippases that translocate undecaprenyl diphosphate-linked oligosaccharides across the cytoplasmic membranes of bacteria. Consequently, MurJ has been proposed to function as the lipid II flippase in
E. coli
. Here, we present a three-dimensional structural model of MurJ generated by the I-TASSER server that suggests that MurJ contains a solvent-exposed cavity within the plane of the membrane. Using
in vivo
topological studies, we demonstrate that MurJ has 14 transmembrane domains and validate features of the MurJ structural model, including the presence of a solvent-exposed cavity within its transmembrane region. Furthermore, we present functional studies demonstrating that specific charged residues localized in the central cavity are essential for function. Together, our studies support the structural homology of MurJ to MOP exporter proteins, suggesting that MurJ might function as an essential transporter in PG biosynthesis.
Functionally Essential Interaction between Yersinia YscO and the T3S4 Domain of YscP
Authors: Mukerjea Romila , Ghosh Partho
Published: August 2013

The type III secretion (T3S) system is essential to the virulence of a large number of Gram-negative bacterial pathogens, including
Yersinia
. YscO is required for T3S in
Yersinia
and is known to interact with several other T3S proteins, including the chaperone SycD and the needle length regulator YscP. To define which interactions of YscO are required for T3S, we pursued model-guided mutagenesis: three conserved and surface-exposed regions of modeled YscO were targeted for multiple alanine substitutions. Most of the mutations abrogated T3S and did so in a recessive manner, consistent with a loss of function. Both functional and nonfunctional YscO mutant proteins interacted with SycD, indicating that the mutations had not affected protein stability. Likewise, both functional and nonfunctional versions of YscO were exclusively intrabacterial. Functional and nonfunctional versions of YscO were, however, distinguishable with respect to interaction with YscP. This interaction was observed only for wild-type YscO and a T3S-proficient mutant of YscO but not for the several T3S-deficient mutants of YscO. Evidence is presented that the YscO-YscP interaction is direct and that the type III secretion substrate specificity switch (T3S4) domain of YscP is sufficient for this interaction. These results provide evidence that the interaction of YscO with YscP, and in particular the T3S4 domain of YscP, is essential to type III secretion.
A meta-analysis of cognitive-based behaviour change techniques as interventions to improve medication adherence
Authors: Easthall Claire , Song Fujian , Bhattacharya Debi
Published: August 2013

Objective

To describe and evaluate the use of cognitive-based behaviour change techniques as interventions to improve medication adherence.

Design

Systematic review and meta-analysis of interventions to improve medication adherence.

Data sources

Search of the MEDLINE, EMBASE, PsycINFO, CINAHL and The Cochrane Library databases from the earliest year to April 2013 without language restriction. References of included studies were also screened to identify further relevant articles.

Review methods

We used predefined criteria to select randomised controlled trials describing a medication adherence intervention that used Motivational Interviewing (MI) or other cognitive-based techniques. Data were extracted and risk of bias was assessed by two independent reviewers. We conducted the meta-analysis using a random effects model and Hedges’ g as the measure of effect size.

Results

We included 26 studies (5216 participants) in the meta-analysis. Interventions most commonly used MI, but many used techniques such as aiming to increase the patient's confidence and sense of self-efficacy, encouraging support-seeking behaviours and challenging negative thoughts, which were not specifically categorised. Interventions were most commonly delivered from community-based settings by routine healthcare providers such as general practitioners and nurses. An effect size (95% CI) of 0.34 (0.23 to 0.46) was calculated and was statistically significant (p < 0.001). Heterogeneity was high with an I2value of 68%. Adjustment for publication bias generated a more conservative estimate of summary effect size of 0.21 (0.08 to 0.33). The majority of subgroup analyses produced statistically non-significant results.

Conclusions

Cognitive-based behaviour change techniques are effective interventions eliciting improvements in medication adherence that are likely to be greater than the behavioural and educational interventions largely used in current practice. Subgroup analyses suggest that these interventions are amenable to use across different populations and in differing manners without loss of efficacy. These factors may facilitate incorporation of these techniques into routine care.
A new species and phylogenetic data for Nematococcomyces
Authors: Tian Hai-Zhen , Yang Zheng , Wang Shuang , Hou Cheng-Lin , Piepenbring Meike
Published: August 2013

Nematococcomyces oberwinkleri sp. nov. is described and illustrated on living twigs of Rhododendron sp. from Yunnan Province, China. It has ascospore appendages similar to the type species N. rhododendri, but differs in its eight-spored asci, ascospore shape, and the gelatinous sheath around the ascospores. Combined large subunit (LSU) rDNA and mitochondrial small subunit (mtSSU) DNA sequences were used to infer the phylogenetic position of Nematococcomyces in the Rhytismatales. Nematococcomyces species formed a monophyletic clade. Pestalotiopsis-like, filiform apical appendages of the ascospores and identity of the associated plant are important characteristics for the genus.
MAGNETOELECTRIC PONDEROMOTIVE FORCE
Authors: BRECHET SYLVAIN D. , ROULET ALEXANDRE , ANSERMET JEAN-PHILIPPE
Published: August 2013

The dynamics of a system consisting of a matter continuum with a weak linear magnetoelectric coupling interacting with electromagnetic fields is examined on a local scale in a nonrelativistic limit. A consistent expression for the internal energy of the system is derived. The internal energy density and the continuity equation for the momentum lead to the derivation of ponderomotive forces. A nonuniform magnetoelectric coupling generates a "magnetoelectric" ponderomotive force that could be distinguished from the purely electric or magnetic ponderomotive forces by applying alternating electric and magnetic fields at distinct frequencies.
DYNAMIC BEHAVIOR ANALYSIS OF A DIFFERENTIAL-ALGEBRAIC PREDATOR–PREY SYSTEM WITH PREY HARVESTING
Authors: LIU WEI , CHEN YUXIAN , FU CHAOJIN
Published: August 2013

This paper studies a differential-algebraic predator–prey system with prey harvesting, which consists of two differential equations and an algebraic equation. By using the differential-algebraic system theory, bifurcation theory and formal series expansions, we investigate the Hopf bifurcation and center stability of the differential-algebraic predator–prey system. Some sufficient conditions on these issues are obtained. In addition, numerical simulations illustrate the effectiveness of our results and their biological implications are discussed.
MINIMIZING THE COMPLETE INFLUENCE TIME IN A SOCIAL NETWORK WITH STOCHASTIC COSTS FOR INFLUENCING NODES
Authors: NI YAODONG , SHI QIAONI
Published: August 2013

In this paper, we study the problem of targeting a set of individuals to trigger a cascade of influence in a social network such that the influence diffuses to all individuals with the minimum time, given that the cost of initially influencing each individual is with randomness and that the budget available is limited. We adopt the incremental chance model to characterize the diffusion of influence, and propose three stochastic programming models that correspond to three different decision criteria respectively. A modified greedy algorithm is presented to solve the proposed models, which can flexibly trade off between solution performance and computational complexity. Experiments are performed on random graphs, by which we show that the algorithm we present is effective.
A MULTI-PERIOD INVENTORY MODEL FOR DETERIORATING ITEMS IN UNCERTAIN ENVIRONMENT
Authors: NING YUFU , YAN LIMEI , SHA HUANBIN
Published: August 2013

A model is constructed for a type of multi-period inventory problem with deteriorating items, in which demands are assumed to be uncertain variables. The objective is to minimize the expected total cost including the ordering cost, inventory holding cost and deteriorating cost under constraints that demands should be satisfied with some service level in each period. To solve the model, two methods are proposed in different cases. When uncertain variables are linear, a crisp equivalent form of the model is provided. For the general cases, a hybrid algorithm integrating the 99-method and genetic algorithm is designed. Two examples are given to illustrate the effectiveness of the model and solving methods.
MAMMOGRAPHIC DENSITY ESTIMATION AND CLASSIFICATION USING SEGMENTATION AND PROGRESSIVE ELIMINATION METHOD
Authors: MAITRA INDRA KANTA , NAG SANJAY , BANDYOPADHYAY SAMIR K.
Published: August 2013

For establishing risk factor of breast cancer requires highly specific breast density measure that can result in a more focused breast cancer prevention, diagnosis and treatment. This paper proposes a new CAD system for density estimation using progressive elimination method. The lower intensity pixels are eliminated in multiple phases by targeting specific intensity bands in each phase, using established statistical techniques. Local Standard Deviation (LSD) values are used to identify significant transitions and MLSD values to isolate the most significant transitions or edges. The results are compared to ACR BI RAD system of classification to establish the risk factor. Accuracy estimation on the proposed segmentation method signifies satisfactory qualitative results. The proposed algorithm implemented on all 322 mammograms of MIAS shows 73.91% agreement. The obtained Kappa (κ) value for the proposed method is 0.673.
Stability of bi-θ-derivations on JB*-triples: Revisited
Authors: Park Choonkil
Published: August 2013

Ebadian et al. [Stability of bi-θ-derivations on JB*-triples, Int. J. Geom. Meth. Mod. Phys.9(7) (2012) 1250051, 12 pp.] proved the Hyers–Ulam stability of bi-θ-derivations on JB*-triples. Under the conditions of the definition of bi-θ-derivation given in the above paper, the bi-θ-derivation must be zero. So the results given in the above paper must be trivial. Under the conditions in the main theorem, we can show that the related mapping must be zero. In this paper, we correct the statements of the results and prove the corrected theorems and corollaries.
PEGYLATED CONJUGATED OLIGOMERS FOR TARGETED TWO-PHOTON FLUORESCENCE IMAGING OF CANCER CELLS
Authors: WANG GUAN , GENG JUNLONG , ZHANG XINHAI , XING GUICHUAN , SUM TZE CHIEN , LAI YEE-HING , LIU BIN
Published: August 2013

A water-dispersible PEGylated conjugated oligomer (PEGTVFVBN) is synthesized for two-photon fluorescence imaging applications. PEGTVFVBN could aggregate into nanoparticles of ~ 110 nm size in H2O , which show a fluorescence quantum yield of 0.12, 20 times higher than that for its cationic counterpart (TVFVBC). Two-photon fluorescence measurement reveals a maximum two-photon absorption (TPA) cross-section of 263 GM at 780 nm based on molecules for PEGTVFVBN nanoparticles in H2O , while the TPA spectra of TVFVBC are barely detectable under the same experimental conditions. The N , N' -diacetylchitobiotic acid conjugated derivative (ChPEGTVFVBN) could also aggregate into nanoparticles of ~ 90 nm sizes, showing a slightly smaller fluorescence quantum yield of 0.08 and a maximum TPA cross-section of 213 GM at 780 nm. ChPEGTVFVBN could be specifically internalized by vimentin over expressing Hela cells through a receptor mediated endocytosis, giving two-photon fluorescence images in a bright and high contrast manner. In addition, both PEGTVFVBN and ChPEGTVFVBN show low cytotoxicity, which is essential for cell imaging applications. This study thus highlights the molecular engineering strategy of PEGylation to construct robust TPA materials for two-photon fluorescence imaging applications.
Beyond the Niche: Tissue-Level Coordination of Stem Cell Dynamics
Authors: O'Brien Lucy Erin , Bilder David
Published: August 2013

Adult animals rely on populations of stem cells to ensure organ function throughout their lifetime. Stem cells are governed by signals from stem cell niches, and much is known about how single niches promote stemness and direct stem cell behavior. However, most organs contain a multitude of stem cell–niche units, which are often distributed across the entire expanse of the tissue. Beyond the biology of individual stem cell–niche interactions, the next challenge is to uncover the tissue-level processes that orchestrate spatial control of stem-based renewal, repair, and remodeling throughout a whole organ. Here we examine what is known about higher order mechanisms for interniche coordination in epithelial organs, whose simple geometry offers a promising entry point for understanding the regulation of niche number, distribution, and activity. We also consider the potential existence of stem cell territories and how tissue architecture may influence niche coordination.
Integrative Mechanisms of Oriented Neuronal Migration in the Developing Brain
Authors: Evsyukova Irina , Plestant Charlotte , Anton E.S.
Published: August 2013

The emergence of functional neuronal connectivity in the developing cerebral cortex depends on neuronal migration. This process enables appropriate positioning of neurons and the emergence of neuronal identity so that the correct patterns of functional synaptic connectivity between the right types and numbers of neurons can emerge. Delineating the complexities of neuronal migration is critical to our understanding of normal cerebral cortical formation and neurodevelopmental disorders resulting from neuronal migration defects. For the most part, the integrated cell biological basis of the complex behavior of oriented neuronal migration within the developing mammalian cerebral cortex remains an enigma. This review aims to analyze the integrative mechanisms that enable neurons to sense environmental guidance cues and translate them into oriented patterns of migration toward defined areas of the cerebral cortex. We discuss how signals emanating from different domains of neurons get integrated to control distinct aspects of migratory behavior and how different types of cortical neurons coordinate their migratory activities within the developing cerebral cortex to produce functionally critical laminar organization.
Methods and Global Environmental Governance
Authors: O'Neill Kate , Weinthal Erika , Marion Suiseeya Kimberly R. , Bernstein Steven , Cohn Avery , Stone Michael W. , Cashore Benjamin
Published: August 2013

This review analyzes the methods being used and developed in global environmental governance (GEG), an applied field that employs insights and tools from a variety of disciplines both to understand pressing environmental problems and to determine how to address them collectively. We find that methods are often underspecified in GEG research. We undertake a critical review of data collection and analysis in three categories: qualitative, quantitative, and modeling and scenario building. We include examples and references from recent studies to show when and how best to utilize these different methods to conduct problem-driven research. GEG problems are often characterized by institutional and issue complexity, linkages, and multiscalarity that pose challenges for many conventional methodological approaches. As a result, given the large methodological toolbox available to applied researchers, we recommend they adopt a reflective, pluralist, and often collaborative approach when choosing methods appropriate to these challenges.
Peripheral δ-opioid receptors attenuate the exercise pressor reflex
Authors: Leal Anna K. , Yamauchi Katsuya , Kim Joyce , Ruiz-Velasco Victor , Kaufman Marc P.
Published: August 2013

In rats with ligated femoral arteries, the exercise pressor reflex is exaggerated, an effect that is attenuated by stimulation of peripheral μ-opioid receptors on group IV metabosensitive afferents. In contrast, δ-opioid receptors are expressed mostly on group III mechanosensitive afferents, a finding that prompted us to determine whether stimulation of these opioid receptors could also attenuate the exaggerated exercise pressor reflex in “ligated” rats. We found femoral arterial injection of [D-Pen2,D-Pen5]enkephalin (DPDPE; 1.0 μg), a δ-opioid agonist, significantly attenuated the pressor and cardioaccelerator components of the exercise pressor reflex evoked by hindlimb muscle contraction in both rats with ligated and patent femoral arteries. DPDPE significantly decreased the pressor responses to muscle mechanoreflex activation, evoked by tendon stretch, in ligated rats only. DPDPE (1.0 μg) had no effect in either group on the pressor and cardioaccelerator responses to capsaicin (0.2 μg), which primarily stimulates group IV afferents. DPDPE (1.0 μg) had no effect on the pressor and cardioaccelerator responses to lactic acid (24 mM), which stimulates group III and IV afferents, in rats with patent femoral arteries but significantly decreased the pressor response in ligated rats. Western blots revealed the amount of protein comprising the δ-opioid receptor was greater in dorsal root ganglia innervating hindlimbs with ligated femoral arteries than in dorsal root ganglia innervating hindlimbs with patent femoral arteries. Our findings support the hypothesis that stimulation of δ-opioid receptors on group III afferents attenuated the exercise pressor reflex.
Microvascular function in younger adults with obesity and metabolic syndrome: role of oxidative stress
Authors: Limberg Jacqueline K. , Harrell John W. , Johansson Rebecca E. , Eldridge Marlowe W. , Proctor Lester T. , Sebranek Joshua J. , Schrage William G.
Published: August 2013

Older adults with cardiovascular disease exhibit microvascular dysfunction and increased levels of reactive oxygen species (ROS). We hypothesized that microvascular impairments begin early in the disease process and can be improved by scavenging ROS. Forearm blood flow (Doppler ultrasound) was measured in 45 young (32 ± 2 yr old) adults ( n = 15/group) classified as lean, obese, and metabolic syndrome (MetSyn). Vasodilation in response to endothelial (ACh) and vascular smooth muscle [nitroprusside (NTP) and epoprostenol (Epo)] agonists was tested before and after intra-arterial infusion of ascorbic acid to scavenge ROS. Vasodilation was assessed as a rise in relative vascular conductance (ml·min−1·dl−1·100 mmHg−1). ACh and NTP responses were preserved ( P = 0.825 and P = 0.924, respectively), whereas Epo responses were lower in obese and MetSyn adults ( P < 0.05) than in lean controls. Scavenging of ROS via infusion of ascorbic acid resulted in an increase in ACh-mediated ( P < 0.001) and NTP-mediated ( P < 0.001) relative vascular conductance across all groups, suggesting that oxidative stress influences vascular responsiveness in adults with and without overt cardiovascular disease risk. Ascorbic acid had no effect on Epo-mediated vasodilation ( P = 0.267). These results suggest that obese and MetSyn adults exhibit preserved endothelium-dependent vasodilation with reduced dependence on prostacyclin and are consistent with an upregulation of compensatory vascular control mechanisms.
SERCA Cys674sulphonylation and inhibition of L-type Ca2+influx contribute to cardiac dysfunction in endotoxemic mice, independent of cGMP synthesis
Authors: Hobai Ion A. , Buys Emmanuel S. , Morse Justin C. , Edgecomb Jessica , Weiss Eric H. , Armoundas Antonis A. , Hou Xiuyun , Khandelwal Alok R. , Siwik Deborah A. , Brouckaert Peter , Cohen Richard A. , Colucci Wilson S.
Published: August 2013

The goal of this study was to identify the cellular mechanisms responsible for cardiac dysfunction in endotoxemic mice. We aimed to differentiate the roles of cGMP [produced by soluble guanylyl cyclase (sGC)] versus oxidative posttranslational modifications of Ca2+transporters. C57BL/6 mice [wild-type (WT) mice] were administered lipopolysaccharide (LPS; 25 μg/g ip) and euthanized 12 h later. Cardiomyocyte sarcomere shortening and Ca2+transients (ΔCai) were depressed in LPS-challenged mice versus baseline. The time constant of Ca2+decay (τCa) was prolonged, and sarcoplasmic reticulum Ca2+load (CaSR) was depressed in LPS-challenged mice (vs. baseline), indicating decreased activity of sarco(endo)plasmic Ca2+-ATPase (SERCA). L-type Ca2+channel current ( ICa,L) was also decreased after LPS challenge, whereas Na+/Ca2+exchange activity, ryanodine receptors leak flux, or myofilament sensitivity for Ca2+were unchanged. All Ca2+-handling abnormalities induced by LPS (the decrease in sarcomere shortening, ΔCai, CaSR, ICa,L, and τCaprolongation) were more pronounced in mice deficient in the sGC main isoform (sGCα1−/−mice) versus WT mice. LPS did not alter the protein expression of SERCA and phospholamban in either genotype. After LPS, phospholamban phosphorylation at Ser16and Thr17was unchanged in WT mice and was increased in sGCα1−/−mice. LPS caused sulphonylation of SERCA Cys674(as measured immunohistochemically and supported by iodoacetamide labeling), which was greater in sGCα1−/−versus WT mice. Taken together, these results suggest that cardiac Ca2+dysregulation in endotoxemic mice is mediated by a decrease in L-type Ca2+channel function and oxidative posttranslational modifications of SERCA Cys674, with the latter (at least) being opposed by sGC-released cGMP.
Mechanistic insight into prolonged electromechanical delay in dyssynchronous heart failure: a computational study
Authors: Constantino Jason , Hu Yuxuan , Lardo Albert C. , Trayanova Natalia A.
Published: August 2013

In addition to the left bundle branch block type of electrical activation, there are further remodeling aspects associated with dyssynchronous heart failure (HF) that affect the electromechanical behavior of the heart. Among the most important are altered ventricular structure (both geometry and fiber/sheet orientation), abnormal Ca2+ handling, slowed conduction, and reduced wall stiffness. In dyssynchronous HF, the electromechanical delay (EMD), the time interval between local myocyte depolarization and myofiber shortening onset, is prolonged. However, the contributions of the four major HF remodeling aspects in extending EMD in the dyssynchronous failing heart remain unknown. The goal of this study was to determine the individual and combined contributions of HF-induced remodeling aspects to EMD prolongation. We used MRI-based models of dyssynchronous nonfailing and HF canine electromechanics and constructed additional models in which varying combinations of the four remodeling aspects were represented. A left bundle branch block electrical activation sequence was simulated in all models. The simulation results revealed that deranged Ca2+ handling is the primary culprit in extending EMD in dyssynchronous HF, with the other aspects of remodeling contributing insignificantly. Mechanistically, we found that abnormal Ca2+ handling in dyssynchronous HF slows myofiber shortening velocity at the early-activated septum and depresses both myofiber shortening and stretch rate at the late-activated lateral wall. These changes in myofiber dynamics delay the onset of myofiber shortening, thus giving rise to prolonged EMD in dyssynchronous HF.
Mechanical ventilation-induced apoptosis in newborn rat lung is mediated via FasL/Fas pathway
Authors: Kroon Andreas A. , DelRiccio Veronica , Tseu Irene , Kavanagh Brian P. , Post Martin
Published: August 2013

Mechanical ventilation induces pulmonary apoptosis and inhibits alveolar development in preterm infants, but the molecular basis for the apoptotic injury is unknown. The objective was to determine the signaling mechanism(s) of ventilation (stretch)-induced apoptosis in newborn rat lung. Seven-day-old rats were ventilated with room air for 24 h using moderate tidal volumes (8.5 ml/kg). Isolated fetal rat lung epithelial and fibroblast cells were subjected to continuous cyclic stretch (5, 10, or 17% elongation) for up to 12 h. Prolonged ventilation significantly increased the number of apoptotic alveolar type II cells (i.e., terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling and anti-cleaved caspase-3 immunochemistry) and was associated with increased expression of the apoptotic mediator Fas ligand (FasL). Fetal lung epithelial cells, but not fibroblasts, subjected to maximal (i.e., 17%, but not lesser elongation) cyclic stretch exhibited increased apoptosis (i.e., nuclear fragmentation and DNA laddering), which appeared to be mediated via the extrinsic pathway (increased expression of FasL and cleaved caspase-3, -7, and -8). The intrinsic pathway appeared not to be involved [minimal mitochondrial membrane depolarization (JC-1 flow analysis) and no activation of caspase-9]. Universal caspases inhibition and neutralization of FasL abrogated the stretch-induced apoptosis. Prolonged mechanical ventilation induces apoptosis of alveolar type II cells in newborn rats and the mechanism appears to involve activation of the extrinsic death pathway via the FasL/Fas system.
Affordances in the Home Environment for Motor Development: A Cross-Cultural Study between American and Lebanese Children
Authors: Ammar Diala , Acevedo Gabriel A. , Cordova Alberto
Published: August 2013

Considerable efforts have been devoted to map the relations between the home environment and selected aspects of child’s development. A recent instrument was developed that aimed at assessing the affordances in the home environment, the AHEMD-SR. Although the AHEMD-SR gave insight into affordances in the home, it was focused on two specific populations from the United States and Portugal. Currently, there is limited research regarding the validity of this instrument when used in different cultures. The purpose of this study was to compare a sample of Middle Eastern children to the normative sample that was used to validate the AHEMD. Results showed a significance difference between the socioeconomic statuses between the groups. Concerning factor analysis, results showed that the Lebanese group had five factors loading as did the American/Portuguese sample but with variables loading differently. Interestingly, the Lebanese group showed higher scores for affordances inside the home such replica toys and games. Our findings show that the state of the environment may play a role in the affordances and development. Future work is needed to look at the specific loading and possible variables that may be included in the AHMED-SR to look at other cultures that may have other limitations.
Application of the Asymptotic Taylor Expansion Method to Bistable Potentials
Authors: Ozer Okan , Koklu Halide , Resitoglu Serap
Published: August 2013

A recent method called asymptotic Taylor expansion (ATEM) is applied to determine the analytical expression for eigenfunctions and numerical results for eigenvalues of the Schrödinger equation for the bistable potentials. Optimal truncation of the Taylor series gives a best possible analytical expression for eigenfunctions and numerical results for eigenvalues. It is shown that the results are obtained by a simple algorithm constructed for a computer system using symbolic or numerical calculation. It is observed that ATEM produces excellent results consistent with the existing literature.