bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of nanoporous TiO2 coating and anodized Ca2+ modification of titanium surfaces on early microbial biofilm formation
Authors: Fröjd Victoria , Linderbäck Paula , Wennerberg Ann , Chávez de Paz Luis , Svensäter Gunnel , Davies Julia R
Published: March 2011

Background

The soft tissue around dental implants forms a barrier between the oral environment and the peri-implant bone and a crucial factor for long-term success of therapy is development of a good abutment/soft-tissue seal. Sol-gel derived nanoporous TiO2 coatings have been shown to enhance soft-tissue attachment but their effect on adhesion and biofilm formation by oral bacteria is unknown.

Methods

We have investigated how the properties of surfaces that may be used on abutments: turned titanium, sol-gel nanoporous TiO2 coated surfaces and anodized Ca2+ modified surfaces, affect biofilm formation by two early colonizers of the oral cavity: Streptococcus sanguinis and Actinomyces naeslundii. The bacteria were detected using 16S rRNA fluorescence in situ hybridization together with confocal laser scanning microscopy.

Results

Interferometry and atomic force microscopy revealed all the surfaces to be smooth (Sa ≤ 0.22 μm). Incubation with a consortium of S. sanguinis and A. naeslundii showed no differences in adhesion between the surfaces over 2 hours. After 14 hours, the level of biofilm growth was low and again, no differences between the surfaces were seen. The presence of saliva increased the biofilm biovolume of S. sanguinis and A. naeslundii ten-fold compared to when saliva was absent and this was due to increased adhesion rather than biofilm growth.

Conclusions

Nano-topographical modification of smooth titanium surfaces had no effect on adhesion or early biofilm formation by S. sanguinis and A. naeslundii as compared to turned surfaces or those treated with anodic oxidation in the presence of Ca2+. The presence of saliva led to a significantly greater biofilm biovolume but no significant differences were seen between the test surfaces. These data thus suggest that modification with sol-gel derived nanoporous TiO2, which has been shown to improve osseointegration and soft-tissue healing in vivo, does not cause greater biofilm formation by the two oral commensal species tested than the other surfaces.
End of life care in sub-Saharan Africa: a systematic review of the qualitative literature
Authors: Gysels Marjolein , Pell Christopher , Straus Lianne , Pool Robert
Published: March 2011

Background

End of life (EoL) care in sub-Saharan Africa still lacks the sound evidence-base needed for the development of effective, appropriate service provision. It is essential to make evidence from all types of research available alongside clinical and health service data, to ensure that EoL care is ethical and culturally appropriate. This article aims to synthesize qualitative research on EoL care in sub-Saharan Africa to inform policy, practice and further research. It seeks to identify areas of existing research; describe findings specifically relevant to the African context; and, identify areas lacking evidence.

Methods

Relevant literature was identified through eight electronic databases: AMED, British Nursing Index & Archive, CINAHL, EMBASE, IBSS, MEDLINE, PsycINFO, and the Social Sciences Citation Index; and hand searches. Inclusion criteria were: published qualitative or mixed-method studies in sub-Saharan Africa, about EoL care. Study quality was assessed using a standard grading scale. Relevant data including findings and practice recommendations were extracted and compared in tabular format.

Results

Of the 407 articles initially identified, 51 were included in the qualitative synthesis. Nineteen came from South Africa and the majority (38) focused on HIV/AIDS. Nine dealt with multiple or unspecified conditions and four were about cancer. Study respondents included health professionals, informal carers, patients, community members and bereaved relatives. Informal carers were typically women, the elderly and children, providing total care in the home, and lacking support from professionals or the extended family. Twenty studies focused on home-based care, describing how programmes function in practice and what is needed to make them effective. Patients and carers were reported to prefer institutional care but this needs to be understood in context. Studies focusing on culture discussed good and bad death, culture-specific approaches to symptoms and illness, and the bereavement process.

Conclusions

The data support or complement the findings from quantitative research. The review prompts a reconsideration of the assumption that in Africa the extended family care for the sick, and that people prefer home-based care. The review identifies areas relevant for a research agenda on socio-cultural issues at the EoL in sub-Saharan Africa.
Exploring new health markets: experiences from informal providers of transport for maternal health services in Eastern Uganda
Authors: Pariyo George W , Mayora Chrispus , Okui Olico , Ssengooba Freddie , Peters David H , Serwadda David , Lucas Henry , Bloom Gerald , Rahman M Hafizur , Ekirapa-Kiracho Elizabeth
Published: March 2011

Background

Although a number of intermediate transport initiatives have been used in some developing countries, available evidence reveals a dearth of local knowledge on the effect of these rural informal transport mechanisms on access to maternal health care services, the cost of implementing such schemes and their scalability. This paper, attempts to provide insights into the functioning of the informal transport markets in facilitating access to maternal health care. It also demonstrates the role that higher institutions of learning can play in designing projects that can increase the utilization of maternal health services.

Objectives

To explore the use of intermediate transport mechanisms to improve access to maternal health services, with emphasis on the benefits and unintended consequences of the transport scheme, as well as challenges in the implementation of the scheme.

Methods

This paper is based on the pilot phase to inform a quasi experimental study aimed at increasing access to maternal health services using demand and supply side incentives. The data collection for this paper included qualitative and quantitative methods that included focus group interviews, review of project documents and facility level data.

Results

There was a marked increase in attendance of antenatal, and delivery care services, with the contracted transporters playing a leading role in mobilizing mothers to attend services. The project also had economic spill-over effects to the transport providers, their families and community generally. However, some challenges were faced including difficulty in setting prices for paying transporters, and poor enforcement of existing traffic regulations.

Conclusions and implications

The findings indicate that locally existing resources such as motorcycle riders, also known as “boda boda” can be used innovatively to reduce challenges caused by geographical inaccessibility and a poor transport network with resultant increases in the utilization of maternal health services. However, care must be taken to mobilize the resources needed and to ensure that there is enforcement of laws that will ensure the safety of clients and the transport providers themselves.
EGFR and EGFRvIII undergo stress- and EGFR kinase inhibitor-induced mitochondrial translocalization: A potential mechanism of EGFR-driven antagonism of apoptosis
Authors: Cao Xinyu , Zhu Hu , Ali-Osman Francis , Lo Hui-Wen
Published: March 2011

Background

Epidermal growth factor receptor (EGFR) plays an essential role in normal development, tumorigenesis and malignant biology of human cancers, and is known to undergo intracellular trafficking to subcellular organelles. Although several studies have shown that EGFR translocates into the mitochondria in cancer cells, it remains unclear whether mitochondrially localized EGFR has an impact on the cells and whether EGFRvIII, a constitutively activated variant of EGFR, undergoes mitochondrial transport similar to EGFR.

Results

We report that both receptors translocate into the mitochondria of human glioblastoma and breast cancer cells, following treatments with the apoptosis inducers, staurosporine and anisomycin, and with an EGFR kinase inhibitor. Using mutant EGFR/EGFRvIII receptors engineered to undergo enriched intracellular trafficking into the mitochondria, we showed that glioblastoma cells expressing the mitochondrially enriched EGFRvIII were more resistant to staurosporine- and anisomycin-induced growth suppression and apoptosis and were highly resistant to EGFR kinase inhibitor-mediated growth inhibition.

Conclusions

These findings indicate that apoptosis inducers and EGFR-targeted inhibitors enhance mitochondrial translocalization of both EGFR and EGFRvIII and that mitochondrial accumulation of these receptors contributes to tumor drug resistance. The findings also provide evidence for a potential link between the mitochondrial EGFR pathway and apoptosis.
Light-emitting diodes enhanced by localized surface plasmon resonance
Authors: Gu Xuefeng , Qiu Teng , Zhang Wenjun , Chu Paul K
Published: March 2011

Light-emitting diodes [LEDs] are of particular interest recently as their performance is approaching fluorescent/incandescent tubes. Moreover, their energy-saving property is attracting many researchers because of the huge energy crisis we are facing. Among all methods intending to enhance the efficiency and intensity of a conventional LED, localized surface plasmon resonance is a promising way. The mechanism is based on the energy coupling effect between the emitted photons from the semiconductor and metallic nanoparticles fabricated by nanotechnology. In this review, we describe the mechanism of this coupling effect and summarize the common fabrication techniques. The prospect, including the potential to replace fluorescent/incandescent lighting devices as well as applications to flat panel displays and optoelectronics, and future challenges with regard to the design of metallic nanostructures and fabrication techniques are discussed.
Grain size-dependent magnetic and electric properties in nanosized YMnO3 multiferroic ceramics
Authors: Han Tai-Chun , Hsu Wei-Lun , Lee Wei-Da
Published: March 2011

Magnetic and electric properties are investigated for the nanosized YMnO3 samples with different grain sizes (25 nm to 200 nm) synthesized by a modified Pechini method. It shows that magnetic and electric properties are strongly dependent on the grain size. The magnetic characterization indicates that with increasing grain size, the antiferromagnetic (AFM) transition temperature increases from 52 to 74 K. A corresponding shift of the dielectric anomaly is observed, indicating a strong correlation between the electric polarization and the magnetic ordering. Further analysis suggests that the rising of AFM transition temperature with increasing grain size should be from the structural origin, in which the strength of AFM interaction as well as the electrical polarization is dependent on the in-plane lattice parameters. Furthermore, among all samples, the sample with grain size of 95 nm is found to have the smallest leakage current density (< 1 μA/cm2).

PACS: 75.50.Tt, 75.50.Ee, 75.85.+t, 77.84.-s
Lithium ion storage between graphenes
Authors: Chan Yue , Hill James M
Published: March 2011

In this article, we investigate the storage of lithium ions between two parallel graphene sheets using the continuous approximation and the 6-12 Lennard-Jones potential. The continuous approximation assumes that the carbon atoms can be replaced by a uniform distribution across the surface of the graphene sheets so that the total interaction potential can be approximated by performing surface integrations. The number of ion layers determines the major storage characteristics of the battery, and our results show three distinct ionic configurations, namely single, double, and triple ion forming layers between graphenes. The number densities of lithium ions between the two graphenes are estimated from existing semi-empirical molecular orbital calculations, and the graphene sheets giving rise to the triple ion layers admit the largest storage capacity at all temperatures, followed by a marginal decrease of storage capacity for the case of double ion layers. These two configurations exceed the maximum theoretical storage capacity of graphite. Further, on taking into account the charge-discharge property, the double ion layers are the most preferable choice for enhanced lithium storage. Although the single ion layer provides the least charge storage, it turns out to be the most stable configuration at all temperatures. One application of the present study is for the design of future high energy density alkali batteries using graphene sheets as anodes for which an analytical formulation might greatly facilitate rapid computational results.
Magnetotransport in quantum cascade detectors: analyzing the current under illumination
Authors: Jasnot François-Régis , Péré-Laperne Nicolas , de Vaulchier Louis-Anne , Guldner Yves , Carosella Francesca , Ferreira Robson , Buffaz Amandine , Doyennette Laetitia , Berger Vincent , Carras Mathieu , Marcadet Xavier
Published: March 2011

Photocurrent measurements have been performed on a quantum cascade detector structure under strong magnetic field applied parallel to the growth axis. The photocurrent shows oscillations as a function of B. In order to describe that behavior, we have developed a rate equation model. The interpretation of the experimental data supports the idea that an elastic scattering contribution plays a central role in the behavior of those structures. We present a calculation of electron lifetime versus magnetic field which suggests that impurities scattering in the active region is the limiting factor. These experiments lead to a better understanding of these complex structures and give key parameters to optimize them further.
Electromodulated reflectance study of self-assembled Ge/Si quantum dots
Authors: Yakimov Andrew , Nikiforov Aleksandr , Bloshkin Aleksei , Dvurechenskii Anatolii
Published: March 2011

We perform an electroreflectance spectroscopy of Ge/Si self-assembled quantum dots in the near-infrared and in the mid-infrared spectral range. Up to three optical transitions are observed. The low-energy resonance is proposed to correspond to a band-to-continuum hole transition in the Ge valence band. The other two modulation signals are attributed to the spatially direct transitions between the electrons confined in the L and Δ(4) valleys of the Ge conduction band, and the localized hole states at the Γ point.
Microscopic study of electrical properties of CrSi2 nanocrystals in silicon
Authors: Dózsa László , Lányi Štefan , Raineri Vito , Giannazzo Filippo , Galkin Nikolay Gennadevich
Published: March 2011

Semiconducting CrSi2 nanocrystallites (NCs) were grown by reactive deposition epitaxy of Cr onto n-type silicon and covered with a 50-nm epitaxial silicon cap. Two types of samples were investigated: in one of them, the NCs were localized near the deposition depth, and in the other they migrated near the surface. The electrical characteristics were investigated in Schottky junctions by current-voltage and capacitance-voltage measurements. Atomic force microscopy (AFM), conductive AFM and scanning probe capacitance microscopy (SCM) were applied to reveal morphology and local electrical properties. The scanning probe methods yielded specific information, and tapping-mode AFM has shown up to 13-nm-high large-area protrusions not seen in the contact-mode AFM. The electrical interaction of the vibrating scanning tip results in virtual deformation of the surface. SCM has revealed NCs deep below the surface not seen by AFM. The electrically active probe yielded significantly better spatial resolution than AFM. The conductive AFM measurements have shown that the Cr-related point defects near the surface are responsible for the leakage of the macroscopic Schottky junctions, and also that NCs near the surface are sensitive to the mechanical and electrical stress induced by the scanning probe.
Divergence of gut permeability and mucosal immune gene expression in two gluten-associated conditions: celiac disease and gluten sensitivity
Authors: Sapone Anna , Lammers Karen M , Casolaro Vincenzo , Cammarota Marcella , Giuliano Maria Teresa , De Rosa Mario , Stefanile Rosita , Mazzarella Giuseppe , Tolone Carlo , Russo Maria Itria , Esposito Pasquale , Ferraraccio Franca , Cartenì Maria , Riegler Gabriele , de Magistris Laura , Fasano Alessio
Published: March 2011

Background

Celiac disease (CD) is an autoimmune enteropathy triggered by the ingestion of gluten. Gluten-sensitive individuals (GS) cannot tolerate gluten and may develop gastrointestinal symptoms similar to those in CD, but the overall clinical picture is generally less severe and is not accompanied by the concurrence of tissue transglutaminase autoantibodies or autoimmune comorbidities. By studying and comparing mucosal expression of genes associated with intestinal barrier function, as well as innate and adaptive immunity in CD compared with GS, we sought to better understand the similarities and differences between these two gluten-associated disorders.

Methods

CD, GS and healthy, gluten-tolerant individuals were enrolled in this study. Intestinal permeability was evaluated using a lactulose and mannitol probe, and mucosal biopsy specimens were collected to study the expression of genes involved in barrier function and immunity.

Results

Unlike CD, GS is not associated with increased intestinal permeability. In fact, this was significantly reduced in GS compared with controls (P = 0.0308), paralleled by significantly increased expression of claudin (CLDN) 4 (P = 0.0286). Relative to controls, adaptive immunity markers interleukin (IL)-6 (P = 0.0124) and IL-21 (P = 0.0572) were expressed at higher levels in CD but not in GS, while expression of the innate immunity marker Toll-like receptor (TLR) 2 was increased in GS but not in CD (P = 0.0295). Finally, expression of the T-regulatory cell marker FOXP3 was significantly reduced in GS relative to controls (P = 0.0325) and CD patients (P = 0.0293).

Conclusions

This study shows that the two gluten-associated disorders, CD and GS, are different clinical entities, and it contributes to the characterization of GS as a condition associated with prevalent gluten-induced activation of innate, rather than adaptive, immune responses in the absence of detectable changes in mucosal barrier function.
Analysis of XMRV integration sites from human prostate cancer tissues suggests PCR contamination rather than genuine human infection
Authors: Garson Jeremy A , Kellam Paul , Towers Greg J
Published: March 2011

XMRV is a gammaretrovirus associated in some studies with human prostate cancer and chronic fatigue syndrome. Central to the hypothesis of XMRV as a human pathogen is the description of integration sites in DNA from prostate tumour tissues. Here we demonstrate that 2 of 14 patient-derived sites are identical to sites cloned in the same laboratory from experimentally infected DU145 cells. Identical integration sites have never previously been described in any retrovirus infection. We propose that the patient-derived sites are the result of PCR contamination. This observation further undermines the notion that XMRV is a genuine human pathogen.
Fish oil rich diet in comparison to saturated fat rich diet offered protection against lipopolysaccharide-induced inflammation and insulin resistance in mice
Authors: Vijay-Kumar Matam , Vanegas Sally M , Patel Nilam , Aitken Jesse D , Ziegler Thomas R , Ganji Vijay
Published: March 2011

Background and Objective

Systemic chronic inflammation is linked to metabolic syndrome, type-2 diabetes, and heart disease. Lipopolysaccharide (LPS), a Gram negative microbial product, triggers inflammation through toll-like-receptor-4 (TLR-4) signaling. It has been reported that dietary fatty acids also modulate inflammation through TLR-4. We investigated whether fish oil (FO) rich diet in comparison to saturated fat (SF) rich diet would confer protection from pathologies induced by LPS.

Methods

Twenty C57BL/6 mice were divided into two groups. One group received FO-diet and other received SF-diet ad libitum for 60 days. Diets were isocaloric containing 45% energy from fat. After 60-days of feeding, blood was collected after overnight fast. Mice were allowed to recover for 4-days, fasted for 5-hours, challenged with 100 ng/mL of LPS intraperitonially, and bled after 2-hours. After 7-days of recuperation, mice were challenged with 500 ng/mL of LPS intraperitonially and observed for physical health.

Results

Food intake was similar in FO- and SF-fed mice. FO-fed mice compared to SF-fed mice had significantly less body weight gain (P = 0.005), epididymal fat weight (P = 0.005), fasting blood glucose (70.8 vs 83.3 ng/dL; P < 0.05), HOMA-IR (5.0 vs 13.6; P < 0.019), and serum cholesterol (167 vs 94 mg/dL; P < 0.05). When challenged with LPS, FO-fed mice had significantly lower serum IL-1β compared to SF-fed mice (2.0 vs 30.0 pg/mL; P < 0.001). After LPS-challenge, SF-fed mice had higher mortality, lost more body weight, and had greater decrease in blood glucose compared to FO-fed mice.

Conclusion

Overall, FO-diet compared to SF-diet offered protection against deleterious effects of LPS in mice.
A primary-school-based study to reduce prevalence of childhood obesity in Catalunya (Spain) - EDAL-Educació en alimentació: study protocol for a randomised controlled trial
Authors: Giralt Montse , Albaladejo Rosa , Tarro Lucia , Moriña David , Arija Victoria , Solà Rosa
Published: March 2011

Background

The EdAL (
Ed

ucació en

Al

imentació) study is a long-term, nutrition educational, primary-school-based program designed to prevent obesity by promoting a healthy lifestyle that includes dietary recommendations and physical activity.

The aims are: 1) to evaluate the effects of a 3-year school-based life-style improvement program on the prevalence of obesity in an area of north-west Mediterranean 2) To design a health-promotion program to be implemented by health-promoter agents (university students) in primary schools.

Methods/Design

1) The intervention study is a randomised, controlled, school-based program performed by university-student health-promoter agents. Initial pupil enrolment was in 2006 and continued for 3 years. We considered two clusters (designated as cluster A and cluster B) as the units for randomisation. The first cluster involved 24 schools from Reus and the second involved 14 schools from surrounding towns Cambrils, Salou and Vilaseca combined in order to obtain comparable groups. There are very good communications between schools in each town, and to avoid cross influence of the programs resulting from inter-school dialogue, the towns themselves were the unit for randomisation. Data collected included name, gender, date and place of birth at the start of the program and, subsequently, weight, height, body mass index (BMI) and waist circumference every year for 3 years. Questionnaires on eating and physical activity habits are filled-in by the parents at the start and end of the study and, providing that informed consent is given, the data are analysed on the intention-to-treat basis.

The interventions are based on 8 nutritional and physical activity objectives. They are implemented by university students as part of the university curriculum in training health-promoter agents. These 8 objectives are developed in 4 educational activities/year for 3 years (a total of 12 activities; 1 h/activity) performed by the health-promoter agents in primary schools. Control pupils follow their usual activities.

2) Courses on education and promotion of health, within in the curriculum of medicine and health sciences for university students, are designed to train health-promoter agents to administer these activities in primary schools.

Discussion

This controlled school-based intervention will test the possibility of preventing childhood obesity.

Trial registration number

ISRCTN: ISRCTN29247645
T cell mediated cerebral hemorrhages and microhemorrhages during passive Aβ immunization in APPPS1 transgenic mice
Authors: Meyer-Luehmann Melanie , Mora J Rodrigo , Mielke Matthew , Spires-Jones Tara L , de Calignon Alix , von Andrian Ulrich H , Hyman Bradley T
Published: March 2011

Background

Immunization against amyloid-β (Aβ), the peptide that accumulates in the form of senile plaques and in the cerebrovasculature in Alzheimer's disease (AD), causes a dramatic immune response that prevents plaque formation and clears accumulated Aβ in transgenic mice. In a clinical trial of Aβ immunization, some patients developed meningoencephalitis and hemorrhages. Neuropathological investigations of patients who died after the trial showed clearance of amyloid pathology, but also a powerful immune response involving activated T cells probably underlying the negative effects of the immunization.

Results

To define the impact of T cells on this inflammatory response we used passive immunization and adoptive transfer to separate the effect of IgG and T cell mediated effects on microhemorrhage in APPPS1 transgenic mice. Neither anti Aβ IgG nor adoptively transferred T cells, alone, led to increased cerebrovascular damage. However, the combination of adoptively transferred T cells and passive immunization led to massive cerebrovascular bleeding that ranged from multiple microhemorrhages in the parenchyma to large hematomas.

Conclusions

Our results indicate that vaccination can lead to Aβ and T cell induced cerebral micro-hemorrhages and acute hematomas, which are greatly exacerbated by T cell mediated activity.
Allogeneic hematopoietic stem cell transplantation for acute leukemia with Gilbert's syndrome
Authors: Yu Guo-Pan , Jiang Qian-Li , Fan Zhi-Ping , Zhao Jie , Wei Qi , Sun Jing , Meng Fan-Yi , Liu Qi-Fa
Published: March 2011

Acute leukemia with coexisting Gilbert's syndrome treated by allogeneic hematopoietic stem cell transplantation (allo-HSCT) is rarely reported. Here we described a case whose transaminase levels were almost normal, although transient hyperbilirubinemia repeatedly happened during chemotherapy.
Biomedical semantics in the Semantic Web
Authors: Splendiani Andrea , Burger Albert , Paschke Adrian , Romano Paolo , Marshall M Scott
Published: March 2011

The Semantic Web offers an ideal platform for representing and linking biomedical information, which is a prerequisite for the development and application of analytical tools to address problems in data-intensive areas such as systems biology and translational medicine. As for any new paradigm, the adoption of the Semantic Web offers opportunities and poses questions and challenges to the life sciences scientific community: which technologies in the Semantic Web stack will be more beneficial for the life sciences? Is biomedical information too complex to benefit from simple interlinked representations? What are the implications of adopting a new paradigm for knowledge representation? What are the incentives for the adoption of the Semantic Web, and who are the facilitators? Is there going to be a Semantic Web revolution in the life sciences?

We report here a few reflections on these questions, following discussions at the SWAT4LS (Semantic Web Applications and Tools for Life Sciences) workshop series, of which this Journal of Biomedical Semantics special issue presents selected papers from the 2009 edition, held in Amsterdam on November 20th.
The anti-inflammatory role of granulocyte colony-stimulating factor in macrophage–dendritic cell crosstalk afterLactobacillus rhamnosusGR-1 exposure
Authors: Martins Andrew J , Spanton Sarah , Sheikh Haroon I , Kim Sung Ouk
Published: March 2011

MΦs are important sensory cells of the innate immune system and regulate immune responses through releasing different combinations of cytokines. In this study, we examined whether cytokines released by MΦs in response to the probiotic bacterial strain GR-1 modulate the responses of DCs. The cytokine profile released by GR-1-treated MΦs was characterized by low levels of TNF-α, GM-CSF, IL-6, and IL-12 but very high levels of G-CSF. GR-1 CM did not induce expression of the shared p40 subunit of IL-12 and IL-23 and costimulatory molecules CD80 or CD86 or increase T cell stimulatory capacity in DCs. However, in G-CSFR-deficient DCs or after antibody-mediated neutralization of G-CSF, GR-1 CM induced IL-12/23 p40 production significantly, indicating that G-CSF within the GR-1 CM inhibits IL-12/23 p40 production induced by other CM components. GR-1 CM and rG-CSF also inhibited LPS-induced IL-12 production at the mRNA and protein levels. The inhibition of IL-12 production by G-CSF was at least in part mediated through inhibition of JNK activation. Finally, splenic DCs of GR-1-injected mice produced less IL-12/23 p40 than those of PBS-injected mice in response to LPS ex vivo, and this was at least partially dependent on exposure to GR-1-induced G-CSF in vivo. Altogether, these results suggest that G-CSF modulates the IL-12/23 p40 response of DCs in the context of the probiotic GR-1 through MΦ–DC crosstalk.
Mechanical anisotropy in the Woodford Shale, Permian Basin: Origin, magnitude, and scale
Authors: Harris Nicholas B. , Miskimins Jennifer L. , Mnich Cheryl A.
Published: March 2011

The rock mechanical properties of shales are critical to how they perform as reservoirs, determining both their tendency to develop natural fractures and their response to hydraulic stimulation. These mechanical properties are, in turn, manifestations of composition, fabric and porosity, and fluid saturations. Such properties also dictate the seismic response of shales, as well as their signature on many well logs. It has long been recognized, or perhaps assumed, that shales are relatively homogeneous in the plane parallel to bedding and relatively heterogeneous in the direction perpendicular to bedding.
Rock physics of organic shales
Authors: Vernik Lev , Milovac Jadranka
Published: March 2011

Several publications over the last 20 years have established that black organic shales are generally characterized by strong velocity anisotropy, low velocity in the bedding-normal direction, and relatively low density and porosity (e.g., Vernik and Nur, 1992; Vernik and Liu, 1997). These rock properties are of interest in seismic attribute studies, but even more so in geomechanical applications related to reservoir characterization and hydraulic fracture stimulation. Organic shales typically, but not necessarily, express strong vertical transverse isotropy (VTI), with axis of symmetry perpendicular to the bedding-parallel lamination and clay-particle-preferred orientation. High-resolution SEM imaging (Figure 1) immediately reveals all these textural features in addition to silt grains and the lenticular distribution of the solid organic matter (kerogen), which in turn is characterized by significant intraparticle porosity in mature shales. Any TI medium is described by the five independent elastic constants ([Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]) and detailed multidirectional ultrasonic core measurements can provide the most accurate means for their adequate evaluation. Single-well sonic- and density-log data fall short of the full TI tensor description resulting in major ambiguities related to empirical correlations.
Understanding geophysical responses of shale-gas plays
Authors: Zhu Yaping , Liu Enru , Martinez Alex , Payne Michael A. , Harris Christopher E.
Published: March 2011

Unconventional resources such as shale gas are becoming increasingly important exploration and production targets. To understand the geophysical responses of shale-gas plays, we use a rock physics relationship, which is constrained with geology and formation-evaluation analysis, to calculate effective properties such as impedance and [Formula: see text]. Numerical studies suggest that in-situ rock para-meters such as mineral composition (e.g., clay, quartz, and calcite) and TOC, as well as the interaction among them, can significantly influence the geophysical responses of the organic-rich rocks, thus providing the basis for the geophysical characterization of shale-gas plays.
Dynamic Regulation of PDX-1 and FoxO1 Expression by FoxA2 in Dexamethasone-Induced Pancreatic β-cells Dysfunction
Authors: Chen Fang , Zhu Yunxia , Tang Xinyi , Sun Yidan , Jia Weiping , Sun Yujie , Han Xiao
Published: March 2011

Transcription factors forkhead box (Fox)O1 and pancreatic and duodenal homeobox-1 (PDX-1) are involved in dexamethasone (DEX)-induced dysfunction in pancreatic β-cells. However, the molecular mechanism underlying the regulation of FoxO1 and PDX-1 expression in β-cells treated with DEX is not fully understood. In this study, we found that DEX markedly increased FoxO1 mRNA and protein expression, whereas it decreased PDX-1 mRNA and protein expression in a dose- and time-dependent manner. Further study showed that FoxA2 was involved in regulation of FoxO1 and PDX-1 expression in DEX-induced pancreatic β-cells dysfunction. Interestingly, we demonstrated for the first time that FoxA2 could bind to the FoxO1 gene promoter and positively regulate FoxO1 expression. Moreover, we found that DEX increased the activity of FoxA2 binding to the FoxO1 promoter but decreased the activity of FoxA2 binding to the PDX-1 promoter of RINm5F cells. Knockdown of FoxA2 by RNA interference inhibited FoxO1 expression and restored PDX-1 expression in pancreatic β-cells treated with DEX. However, DEX had no effect on the expression of FoxA2. Together, the results of the present study demonstrated that FoxA2 could dynamically regulate FoxO1 and PDX-1 expression in pancreatic β-cells treated with DEX, which provides new important information on the transcriptional regulation of FoxO1 and PDX-1 in DEX-induced pancreatic β-cells. Inhibition of FoxA2 can effectively protect β-cells against DEX-induced dysfunction.
Regulation of MT1-MMP and MMP-2 by Leptin in Cardiac Fibroblasts Involves Rho/ROCK-Dependent Actin Cytoskeletal Reorganization and Leads to Enhanced Cell Migration
Authors: Schram Kristin , Ganguly Riya , No Eun Kyung , Fang Xiangping , Thong Farah S. L. , Sweeney Gary
Published: March 2011

Altered leptin action has been implicated in the pathophysiology of heart failure in obesity, a hallmark of which is extracellular matrix remodeling. Here, we characterize the direct influence of leptin on matrix metalloproteinase (MMP) activity in primary adult rat cardiac fibroblasts and focus on elucidating the molecular mechanisms responsible. Leptin increased expression and cell surface localization of membrane type 1 (MT1)-MMP, measured by cell surface biotinylation assay and antibody-based colorimetric detection of an exofacial epitope in intact cells. Coimmunoprecipitation analysis showed that leptin also induced the formation of a cluster of differentiation 44/MT1-MMP complex. Qualitative analysis using rhodamine-conjugated phalloidin immunofluorescence indicated that leptin stimulated actin cytoskeletal reorganization and enhanced stress fiber formation. Hence, we analyzed activation of Ras homolog gene family (Rho), member A GTPase activity and found a rapid increase in response to leptin that corresponded with increased phosphorylation of cofilin. Quantitative analysis of cytoskeleton reorganization upon separation of globular and filamentous actin by differential centrifugation confirmed the significant increase in filamentous to globular actin ratio in response to leptin, which was prevented by pharmacological inhibition of Rho (C3 transferase) or its downstream effector kinase Rho-associated coiled-coil-forming protein kinase (ROCK) (Y-27632). Inhibition of Rho or ROCK also attenuated leptin-stimulated increases in cell surface MT1-MMP content. Pro-MMP-2 is a known MT1-MMP substrate, and we observed that enhanced cell surface MT1-MMP in response to leptin resulted in enhanced extracellular activation of pro-MMP-2 measured by gelatin zymography, which was again attenuated by inhibition of Rho or ROCK. Using wound scratch assays, we observed enhanced cell migration, but not proliferation, measured by 5-bromo2′-deoxy-uridine incorporation, in response to leptin, again via a Rho-dependent signaling mechanism. Our results suggest that leptin regulates myocardial matrix remodeling by regulating the cell surface localization of MT1-MMP in adult cardiac fibroblasts via Rho/ROCK-dependent actin cytoskeleton reorganization. Subsequent pro-MMP-2 activation then contributes to stimulation of cell migration.
Couplons in rat atria form distinct subgroups defined by their molecular partners
Authors: Schulson Meredith N. , Scriven David R. L. , Fletcher Patrick , Moore Edwin D. W.
Published: March 2011

Standard local control theory, which describes Ca2+ release during excitation–contraction coupling (ECC), assumes that all ryanodine receptor 2 (RyR2) complexes are equivalent. Findings from our laboratory have called this assumption into question. Specifically, we have shown that the RyR2 complexes in ventricular myocytes are different, depending on their location within the cell. This has led us to hypothesize that similar differences occur within the rat atrial cell. To test this hypothesis, we have triple-labelled enzymatically isolated fixed myocytes to examine the distribution and colocalization of RyR2, calsequestrin (Casq), voltage-gated Ca2+ channels (Cav1.2), the sodium–calcium exchanger (Ncx) and caveolin-3 (Cav3). A number of different surface RyR2 populations were identified, and one of these groups, in which RyR2, Cav1.2 and Ncx colocalized, might provide the structural basis for ‘eager’ sites of Ca2+ release in atria. A small percentage of the dyads containing RyR2 and Cav1.2 were colocalized with Cav3, and therefore could be influenced by the signalling molecules it anchors. The majority of the RyR2 clusters were tightly linked to Cav1.2, and, whereas some were coupled to both Ca 1.2 and Ncx, none were with Ncx alone. This suggests that Cav1.2-mediated Ca2+ -induced Ca2+ release is the primary method of ECC. The two molecules studied that were found in the interior of atrial cells, RyR2 and Casq, showed significantly less colocalization and a reduced nearest-neighbour distance in the interior, compared with the surface of the cell. These differences might result in a higher excitability for RyR2 in the interior of the cells, facilitating the spread of excitation from the periphery to the centre. We also present morphometric data for all of the molecules studied, as well as for those colocalizations found to be significant.
Stimulus predictability mediates a switch in locomotor smooth pursuit performance for Eigenmannia virescens
Authors: Roth Eatai , Zhuang Katie , Stamper Sarah A. , Fortune Eric S. , Cowan Noah J.
Published: March 2011

The weakly electric glass knifefish, Eigenmannia virescens, will swim forward and backward, using propulsion from an anal ribbon fin, in response to motion of a computer-controlled moving refuge. Fish were recorded performing a refuge-tracking behavior for sinusoidal (predictable) and sum-of-sines (pseudo-random) refuge trajectories. For all trials, we observed high coherence between refuge and fish trajectories, suggesting linearity of the tracking dynamics. But superposition failed: we observed categorical differences in tracking between the predictable single-sine stimuli and the unpredictable sum-of-sines stimuli. This nonlinearity suggests a stimulus-mediated adaptation. At all frequencies tested, fish demonstrated reduced tracking error when tracking single-sine trajectories and this was typically accompanied by a reduction in overall movement. Most notably, fish demonstrated reduced phase lag when tracking single-sine trajectories. These data support the hypothesis that fish generate an internal dynamical model of the stimulus motion, hence improving tracking of predictable trajectories (relative to unpredictable ones) despite similar or reduced motor cost. Similar predictive mechanisms based on the dynamics of stimulus movement have been proposed recently, but almost exclusively for nonlocomotor tasks by humans, such as oculomotor target tracking and posture control. These data suggest that such mechanisms might be common across taxa and behaviors.
Temperature effects on Ca2+ cycling in scombrid cardiomyocytes: a phylogenetic comparison
Authors: Galli Gina L. J. , Lipnick Michael S. , Shiels Holly A. , Block Barbara A.
Published: March 2011

Specialisations in excitation–contraction coupling may have played an important role in the evolution of endothermy and high cardiac performance in scombrid fishes. We examined aspects of Ca2+ handling in cardiomyocytes from Pacific bonito (Sarda chiliensis), Pacific mackerel (Scomber japonicus), yellowfin tuna (Thunnus albacares) and Pacific bluefin tuna (Thunnus orientalis). The whole-cell voltage-clamp technique was used to measure the temperature sensitivity of the L-type Ca2+ channel current (ICa), density, and steady-state and maximal sarcoplasmic reticulum (SR) Ca2+ content (ssSRload and maxSRload). Current–voltage relations, peak ICa density and charge density of ICa were greatest in mackerel and yellowfin at all temperatures tested. ICa density and kinetics were temperature sensitive in all species studied, and the magnitude of this response was not related to the thermal preference of the species. SRload was greater in atrial than in ventricular myocytes in the Pacific bluefin tuna, and in species that are more cold tolerant (bluefin tuna and mackerel). ICa and SRload were particularly small in bonito, suggesting the Na+/Ca2+ exchanger plays a more pivotal role in Ca2+ entry into cardiomyocytes of this species. Our comparative approach reveals that the SR of cold-tolerant scombrid fishes has a greater capacity for Ca2+ storage. This specialisation may contribute to the temperature tolerance and thermal niche expansion of the bluefin tuna and mackerel.
Social thermoregulation and torpor in the Siberian hamster
Authors: Jefimow Małgorzata , Głąbska Marta , Wojciechowski Michał S.
Published: March 2011

Social thermoregulation and huddling bring about energy benefits to animals sharing a nest because of the smaller surface-to-volume ratio of a huddle and the higher local temperature in the nest. We tested whether living in groups and huddling affect daily torpor, metabolic rate and seasonal changes in the body mass of a small heterothermic rodent, the Siberian hamster (Phodopus sungorus), housed under semi-natural conditions both singly and in groups of four litter-mates. We predicted that in hamsters housed in groups: (1) synchronized torpor bouts would be longer and deeper than non-synchronized ones but shallower than in solitary hamsters, (2) seasonal variations in metabolic rate would be lower than in solitary hamsters, and (3) the winter decrease in body mass would be smaller in grouped than in singly housed hamsters. We found that group housing led to a smaller decrease in body mass in winter, and affected the length and depth of daily torpor. In group-living hamsters more than 50% of all torpor episodes were synchronized and torpid animals were often found in huddles formed of all cage-mates. The longest and deepest torpor bouts in groups were recorded when all animals in a group entered torpor simultaneously. Although the minimum body temperature during torpor was higher, torpor duration was slightly longer than in solitary hamsters. We did not record significant differences in the body mass-adjusted rate of oxygen consumption between solitary and grouped animals, either in the cold or at the lower critical temperature. We conclude that social thermoregulation enables maintenance of a larger body mass, and thus a larger body fat content, which can ensure better body condition at the beginning of the reproductive season.
The effect of ambient humidity and metabolic rate on the gas-exchange pattern of the semi-aquatic insectAquarius remigis
Authors: Contreras Heidy L. , Bradley Timothy J.
Published: March 2011

We have examined the effects of temperature on metabolic rate and respiratory pattern in the water strider Aquarius remigis. As temperature was increased from 10 to 30°C, the metabolic rate of the insects increased and the respiratory pattern transitioned from discontinuous, to cyclic, to continuous. The discontinuous gas-exchange cycle (DGC) was observed even in insects standing on water when the respirometry chamber was being perfused with humid (>95% relative humidity) air. Comparisons of insects at 20°C in humid and dry air showed no statistically significant differences in metabolic rate or respiratory pattern (P>0.05). The proportion of time that the spiracles were closed was greater at 10°C than at 20°C (P<0.01), and greater at 20°C than at 30°C (P<0.05). These results are compatible with the hypothesis that the respiratory patterns of insects are determined by the relationship between oxygen supply and oxygen demand. There was no evidence in this insect that humidity had any effect on the respiratory pattern. The results are discussed in the context of the ongoing discussion in the literature of the origin, maintenance and adaptive significance of the DGC in insects.
Scaling of caterpillar body properties and its biomechanical implications for the use of a hydrostatic skeleton
Authors: Lin Huai-Ti , Slate Daniel J. , Paetsch Christopher R. , Dorfmann A. Luis , Trimmer Barry A.
Published: March 2011

Caterpillars can increase their body mass 10,000-fold in 2 weeks. It is therefore remarkable that most caterpillars appear to maintain the same locomotion kinematics throughout their entire larval stage. This study examined how the body properties of a caterpillar might change to accommodate such dramatic changes in body load. Using Manduca sexta as a model system, we measured changes in body volume, tissue density and baseline body pressure, and the dimensions of load-bearing tissues (the cuticle and muscles) over a body mass range from milligrams to several grams. All Manduca biometrics relevant to the hydrostatic skeleton scaled allometrically but close to the isometric predictions. Body density and pressure were almost constant. We next investigated the effects of scaling on the bending stiffness of the caterpillar hydrostatic skeleton. The anisotropic non-linear mechanical response of Manduca muscles and soft cuticle has previously been quantified and modeled with constitutive equations. Using biometric data and these material laws, we constructed finite element models to simulate a hydrostatic skeleton under different conditions. The results show that increasing the internal pressure leads to a non-linear increase in bending stiffness. Increasing the body size results in a decrease in the normalized bending stiffness. Muscle activation can double this stiffness in the physiological pressure range, but thickening the cuticle or increasing the muscle area reduces the structural stiffness. These non-linear effects may dictate the effectiveness of a hydrostatic skeleton at different sizes. Given the shared anatomy and size variation in Lepidoptera larvae, these mechanical scaling constraints may implicate the diverse locomotion strategies in different species.