bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Nucleotides in the Immune and Gastrointestinal Systems
Authors: Hess Jennifer R. , Greenberg Norman A.
Published: March 2012

Nucleotides are low molecular weight biological molecules key to biochemical processes. Sources include de novo synthesis, recovery via salvage mechanisms, and dietary intakes. Although endogenous production serves as the main nucleotide source, evidence suggests that exogenous sources are essential to immune competence, intestinal development, and recovery. Dietary nucleotides serve a marked role in rapidly proliferating cells where they are necessary for optimal function. Accordingly, dietary nucleotides are deemed conditionally essential in the presence of various physiological stresses, including growth and development, recovery from injury, infection, and certain disease states. Clinical studies that evaluated nutrition formulations of nucleotides in combination with other specific nutrient substances demonstrated improved clinical outcomes in patients characterized as critically ill, injured, immune suppressed, or with chronic gastrointestinal conditions. However, conclusions regarding specific benefits of nucleotides are limited. Scientific substantiation of nucleotide supplementation in infant formula has been reported to improve the maturation and development of the intestinal tract as well as immune function. All medical nutrition products except for one immune‐modulating formulation are devoid of nucleotides. In an effort to build on this, the current review presents the data to support potential clinical applications for nucleotides in enteral nutrition that may contribute to improved outcomes in physiologically stressed patients.
The Pharmacotherapy Implications of Ventricular Assist Device in the Patient With End-Stage Heart Failure
Authors: Ruden Serena A. S. Von , Murray Margaret A. , Grice Jennifer L. , Proebstle Amy K. , Kopacek Karen J.
Published: March 2012

Advances in mechanical circulatory support, such as the use of ventricular assist devices (VADs), have become a means for prolonging survival in end-stage heart failure (HF). VADs decrease the symptoms of HF and improve quality of life by replacing some of the work of a failing heart. They unload the ventricle to provide improved cardiac output and end-organ perfusion, resulting in improvement in cardiorenal syndromes and New York Heart Association functional class rating. VADs are currently used as a bridge to heart transplantation, a bridge to recovery of cardiac function, or as destination therapy. Complications of VAD include bleeding, infections, arrhythmias, multiple organ failure, right ventricular failure, and neurological dysfunction. Patients with VAD have unique pharmacotherapeutic requirements in terms of anticoagulation, appropriate antibiotic selection, and continuation of HF medications. Pharmacists in acute care and community settings are well prepared to care for the patient with VAD. These patients require thorough counseling and follow-up with regard to prevention and treatment of infections, appropriate levels of anticoagulation, and maintenance of fluid balance. A basic understanding of this unique therapy can assist pharmacists in attending to the needs of patients with VAD.
Facebook and the diffusion of innovation in New Zealand public libraries
Authors: Neo Emily , Calvert Philip J
Published: March 2012

The decision by public libraries in New Zealand to implement Facebook has been uneven. Using Rogers’ Diffusion of Innovations theory, a survey of nine public libraries investigated the process of its adoption or non-adoption. The motivating factors for the adoption of Facebook were identified. The surveyed libraries all met the four prior conditions for its adoption. In the innovation-decision process libraries fulfilled the knowledge stage to differing degrees. In the persuasion stage the attributes of relative advantage, compatibility and complexity were the most important factors to explain adoption. Other factors favouring adoption, such as the importance of change agents, were also discovered.
An Exploration of Patient Perceptions of Adherence to Tuberculosis Treatment in Tanzania
Authors: van den Boogaard Jossy , Msoka Elisabeth , Homfray Mike , Kibiki Gibson S. , Heldens Jeannette J. H. M. , Felling Albert J. A. , Aarnoutse Rob E.
Published: March 2012

In this study, we aimed to explore patient perceptions of adherence to tuberculosis (TB) treatment and construct a theoretical model of treatment adherence behavior. We conducted semistructured interviews with 11 adherent patients from Tanzania whom we recruited by purposive sampling. The interview data were analyzed by content analysis. We found that the patient’s intention to adhere is the most important determinant of adherence behavior. This intention is preceded by the decision to seek biomedical health care, and based on knowledge and beliefs about TB treatment and the motivation to be cured. The intention to adhere helps patients to cope with perceived barriers to adherence, such as socioeconomic difficulties, and to create an adherence-enabling environment in which the presence of social support plays an important role. Our preliminary adherence behavior model should be validated in larger, nonadherent patient populations and evaluated for its applicability to the development of adherence-promoting strategies.
Estimating Implicit Marginal Tax Rates of Welfare Recipients across the US States
Authors: Leguizamon J. Sebastian
Published: March 2012

This article provides a more accurate estimate of implicit marginal tax rates (IMTRs) faced by low-income households in all fifty states. Complications arising from multiple program participation, regional differences in wage regulations, and cost of living make former generalizations about representative low-income households in a state potentially problematic. Additionally, it is appropriate to account for differences in work requirements by choosing the relevant margin to estimate the IMTR, and these margins vary by state. This article is the first to consider these margins, and, indeed, the author finds significant variation of IMTRs for different states. One of biggest sources of variation is the structure of child care subsidies provisions and cost. However, changes made to initial assumptions causes the estimated rates to vary in unpredictable ways. Given this complicated and unpredictable nature of the variation, researchers should exercise caution when using estimated IMTRs to examine work incentives of welfare programs.
Spontaneous pleasures: Sex between women in public places
Authors: Albert Sasha
Published: March 2012

There is a dearth of academic work on public sex among women, especially compared to the wealth of information about men's public sex cultures. To address this disparity, an exploratory study was carried out in which queer women were interviewed to collect their opinions about and experiences with public sex. Based on their responses, queer women have public sex in an unplanned manner, and often within relationships, rejecting the dominant paradigm of men's anonymous cruising cultures. This research indicates that there should be future study on women's public sex, as well as on a wider variety of public sexual behaviors among and between men and women.
The South African Support System for Start-Up Companies: Assessing the Khula Indemnity Scheme
Authors: Gstraunthaler Thomas , Cramer Peter
Published: March 2012

This article examines the South African financial system for start-up companies, and focuses particularly on the support provided by the Khula indemnification scheme. Most research rests on the assumption that a lack of finance is the sole impediment to success of start-ups; however, it is unclear whether such government intervention can indeed foster successful entrepreneurial activity. We show that the current system provides profit-making opportunities for both banks and consultants, but lacks a focus on sustainable business development. There are incentives to create companies not in an attempt to be profitable, but rather as a means to gain access to government or government-backed money. We question whether a lack of finance is the primary obstacle to the formation of businesses. Instead, we argue that it is a lack of accountability and an insufficient application of business tools such as basic cost accounting that make entrepreneurs less creditworthy.
‘It's Not Easy Being Green’: Electricity Corporations and the Transition to a Low-Carbon Economy
Authors: Snell Darryn , Schmitt David
Published: March 2012

If costly and catastrophic climate change is to be avoided, there is an immediate need to stabilize and reduce the level of greenhouse gas emissions (GHGs) entering the atmosphere. The electricity generation sector, responsible for the highest percentage of the world's GHGs, is under mounting social and political pressure to minimize its GHG emissions. In many countries privatization has resulted in previously vertically integrated public electricity utilities being owned and managed by large energy corporations. The implications of electricity privatization for addressing major environmental issues such as climate change were not considered by governments at the time of sale nor have they been widely studied or understood since. This article adopts a political economy approach to examine corporate behaviour in the electricity generation sector and whether private ownership of this sector impacts on state action to reduce emissions. In examining this issue, we consider the carbon strategies of four energy corporations with a stake in Australia's power generation industry. We consider the relationship between the policy statements of these firms on climate change and carbon emission reductions with the action and strategies of their carbon-intensive power generation assets in the Australian state of Victoria. This integrated analysis and assessment of responses at the various organizational levels of these corporations highlights their complex, and in some cases contradictory, responses towards climate change mitigation and how their behaviour constitutes a significant barrier to GHG emission policies.
The maximal and minimal ranks of matrix expression with applications
Authors: Xiong Zhiping , Qin Yingying , Yuan Shifang
Published: March 2012

We give in this article the maximal and minimal ranks of the matrix expression A-B
1
V
1
C
1-B
2
V
2
C
2-B
3
V
3
C
3-B
4
V
4
C
4 with respect to V
1, V
2, V
3, and V
4. As applications, we derive the extremal ranks of the generalized Schur complement A - BM
(1)
C - DN
(1)
G and the partial matrix (A BM
(1)
C DN
(1)
G) with respect to the generalized inverse M
(1) ε M{1} and N
(1) ∈ N{1}.

AMS classifications: 15A03; 15A09; 15A24.
The identification of job opportunities for severely disabled sick-listed employees
Authors: Broersen Jake PJ , Mulders Henny PG , Schellart Antonius JM , van der Beek Allard J
Published: March 2012

Background

Work disability is a major problem for both the worker and society. To explore the work opportunities in regular jobs of persons low in functional abilities, we tried to identify occupations low in task demands. Because of the variety of functional abilities and of the corresponding work demands, the disabled persons need to be classified by type of disability in a limited number of subgroups. Within each subgroup, occupations judged suitable for the most seriously disabled will be selected as having a very low level of the corresponding task demands. These occupations can be applied as reference occupations to assess the presence or absence of work capacity of sick-listed employees in regular jobs, and as job opportunities for people with a specific type of functional disability.

Methods

Registered data from 50,931 disability assessments within the Dutch social security system were used in a second order factor analysis to identify types of disabilities in claimants for a disability pension. Threshold values were chosen to classify claimants according to the severity of the disability. In the disability assessment procedure, a labour expert needs to select jobs with task demands not exceeding the functional abilities of the claimant. For each type of disability, the accessible jobs for the subgroup of the most severely disabled claimants were identified as lowest in the corresponding demand.

Results

The factor analysis resulted in four types of disabilities: general physical ability; autonomy; psychological ability; and manual skills. For each of these types of disablement, a set of four to six occupations low in task demands were selected for the subgroup of most severely disabled claimants. Because of an overlap of the sets of occupations, 13 occupations were selected in total. The percentage of claimants with at least one of the occupations of the corresponding set (the coverage), ranged from 84% to 93%. An alternative selection of six occupations for all subgroups with even less overlap had a coverage ranging from 84% to 89% per subgroup.

Conclusion

This study resulted in two proposals for a set of reference occupations. Further research will be needed to compare the results of the new method of disability assessment to the results of the method presently used in practice.
Effects of Litchi chinensis fruit isolates on prostaglandin E2 and nitric oxide production in J774 murine macrophage cells
Authors: Zhou Yang , Wang Hong , Yang Ruili , Huang Hui , Sun Yuanming , Shen Yudong , Lei Hongtao , Gao Hong
Published: March 2012

Background

Litchi chinensis is regarded as one of the 'heating' fruits in China, which causes serious inflammation symptoms to people.

Methods

In the current study, the effects of isolates of litchi on prostaglandin E2 (PGE2) and nitric oxide (NO) production in J774 murine macrophage cells were investigated.

Results

The AcOEt extract (EAE) of litchi was found effective on stimulating PGE2 production, and three compounds, benzyl alcohol, hydrobenzoin and 5-hydroxymethyl-2-furfurolaldehyde (5-HMF), were isolated and identified from the EAE. Benzyl alcohol caused markedly increase in PGE2 and NO production, compared with lipopolysaccharide (LPS) as positive control, and in a dose-dependent manner. Hydrobenzoin and 5-HMF were found in litchi for the first time, and both of them stimulated PGE2 and NO production moderately in a dose-dependent manner. Besides, regulation of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) mRNA expression and NF-κB (p50) activation might be involved in mechanism of the stimulative process.

Conclusion

The study showed, some short molecular compounds in litchi play inflammatory effects on human.
Pharmacist counseling to cardiac patients in Israel prior to discharge from hospital contribute to increasing patient's medication adherence closing gaps and improving outcomes
Authors: Bisharat Bishara , Hafi Lubna , Baron-Epel Orna , Armaly Zaher , Bowirrat Abdalla
Published: March 2012

Background

Medication non adherence is a global epidemic perplexing phenomenon that is eminent, but not insurmountable. Our first objective was to explore whether providing pharmacist's counseling to cardiac patients prior to discharge can increase patient's medication adherence, and our second objective was to assess whether better medication adherence leads to reduction of hospital readmissions.

Methods

Observational study was conducted among diagnosed cardiac patients using an intervention strategy at discharge from two hospitals in Israel; The Nazareth and the Haemek hospital. 74 patients were recruited between January 2010 and January 2011. Two separate groups were selected; intervention group: 33 patients who prior to discharge received nurse, pharmacist interventions, and control group: 41 patients who had received the nurse and hospital discharge counseling only.

Results

Regression analysis for examining the first objective reflected significant effect when having a pharmacist interventions, which explains the increasing 11.6% of the variance in medication adherence, [F change (1,73) = 9.43,p< 0.003]. Stepwise regression analysis for examining the second objective demonstrated that the relation between medication adherence and readmissions was insignificant [F(1,73)= 9.43, n.s].

Conclusions

While physicians and nurses can have an impact on improving adherence, pharmacists have demonstrated the ability to inform, problem-solve and provide performance support directly to patients.
Second-order-like cluster-monomer transition within magnetic fluids and its impact upon the magnetic susceptibility
Authors: Zhong Jing , Xiang Qing , Massa Letícia O , Qu Fanyao , Morais Paulo C , Liu Wenzhong
Published: March 2012

The low-field (below 5 Oe) ac and dc magnetic response of a magnetic fluid [MF] sample in the range of 305 to 360 K and 410 to 455 K was experimentally and theoretically investigated. We found a systematic deviation of Curie's law, which predicts a linear temperature dependence of inverse initial susceptibility in the range of our investigation. This finding, as we hypothesized, is due to the onset of a second-order-like cluster-to-monomer transition with a critical exponent which is equal to 0.50. The susceptibility data were well fitted by a modified Langevin function, in which cluster dissociation into monomers, at the critical temperature [T*], was included. In the ac experiments, we found thatT*was reducing from 381.8 to 380.4 K as the frequency of the applied field increases from 123 to 173 Hz. In addition, our ac experiments confirm that only monomers respond for the magnetic behavior of the MF sample aboveT*. Furthermore, our Monte Carlo simulation and analytical results support the hypothesis of a thermal-assisted dissociation of chain-like structures.

PACS:75.75.-C; 75.30.Kz; 75.30.Cr.
Amorphous silicon nanocone array solar cell
Authors: Thiyagu Subramani , Pei Zingway , Jhong Ming-Sian
Published: March 2012

In the hydrogenated amorphous silicon [a-Si:H]-thin film solar cell, large amounts of traps reduce the carrier's lifetime that limit the photovoltaic performance, especially the power conversion efficiency. The nanowire structure is proposed to solve the low efficiency problem. In this work, we propose an amorphous silicon [a-Si]-solar cell with a nanocone array structure were implemented by reactive-ion etching through a polystyrene nanosphere template. The amorphous-Si nanocone exhibits absorption coefficient around 5 × 105/cm which is similar to the planar a-Si:H layer in our study. The nanostructure could provide the efficient carrier collection. Owing to the better carrier collection efficiency, efficiency of a-Si solar cell was increased from 1.43% to 1.77% by adding the nanocone structure which has 24% enhancement. Further passivation of the a-Si:H surface by hydrogen plasma treatment and an additional 10-nm intrinsic-a-Si:H layer, the efficiency could further increase to 2.2%, which is 54% enhanced as compared to the planar solar cell. The input-photon-to-current conversion efficiency spectrum indicates the efficient carrier collection from 300 to 800 nm of incident light.
Regulation of cell proliferation and cell density by the inorganic phosphate transporter PiT1
Authors: Byskov Kristina , Jensen Nina , Kongsfelt Iben Boutrup , Wielsøe Maria , Pedersen Lasse Ebdrup , Haldrup Christa , Pedersen Lene
Published: March 2012

Abstact

Background

The inorganic phosphate (Pi) transporter, PiT1 (SLC20A1), is ubiquitously expressed in mammalian cells. It has previously been shown that down-regulation of PiT1 severely impaired the proliferation of two transformed human cells lines, HepG2 and HeLa, and the tumorigenicity of HeLa cells in nude mice. Moreover, PiT1 knock-out mice do not survive past E12.5 and from E10.5, the embryos were found to be growth-retarded and showed reduced proliferation of liver cells. Isolated mouse embryonic fibroblasts with knocked out as well as reduced PiT1 expression levels also exhibited impaired proliferation. Together these results suggest that a certain level of PiT1 is important for proliferation. We have here investigated the role of PiT1 in regulation of cell proliferation using two strictly density-inhibited cells lines, the murine MC3T3-E1 and NIH3T3 cells.

Results

We found that knock-down of PiT1 in MC3T3-E1 cells led to impaired proliferation supporting that at least a certain level of PiT1 is important for wildtype level of proliferation. We, however, also observed that MC3T3-E1 and NIH3T3 cells themselves regulate their endogenous PiT1 mRNA levels with lower levels in general correlating with decreased proliferation/increased cell density. Moreover, over-expression of human PiT1 led to increased proliferation of both MC3T3-E1 and NIH3T3 cultures and resulted in higher cell densities in cultures of these two strictly density-inhibited cell lines. In addition, when we transformed NIH3T3 cells by cultivation in fetal bovine serum, cells over-expressing human PiT1 formed more colonies in soft agar than control cells.

Conclusions

We conclude that not only is a certain level of PiT1 necessary for normal cell division as suggested by previously published studies, rather the cellular PiT1 level is involved in regulating cell proliferation and cell density and an increased PiT1 expression can indeed make NIH3T3 cells more sensitive to transformation. We have thus provided the first evidence for that expression of the type III Pitransporter, PiT1, above the endogenous level can drive cell proliferation and overrule cell density constraints, and the results bridge previous observations showing that a certain PiT1 level is important for regulating normal embryonic growth/development and for tumorigenicity of HeLa cells.
Advanced biorefinery in lower termite-effect of combined pretreatment during the chewing process
Authors: Ke Jing , Laskar Dhrubojyoti D , Gao Difeng , Chen Shulin
Published: March 2012

Background

Currently the major barrier in biomass utilization is the lack of an effective pretreatment of plant cell wall so that the carbohydrates can subsequently be hydrolyzed into sugars for fermentation into fuel or chemical molecules. Termites are highly effective in degrading lignocellulosics and thus can be used as model biological systems for studying plant cell wall degradation.

Results

We discovered a combination of specific structural and compositional modification of the lignin framework and partial degradation of carbohydrates that occurs in softwood with physical chewing by the termite,Coptotermes formosanus, which are critical for efficient cell wall digestion. Comparative studies on the termite-chewed and native (control) softwood tissues at the same size were conducted with the aid of advanced analytical techniques such as pyrolysis gas chromatography mass spectrometry, attenuated total reflectance Fourier transform infrared spectroscopy and thermogravimetry. The results strongly suggest a significant increase in the softwood cellulose enzymatic digestibility after termite chewing, accompanied with utilization of holocellulosic counterparts and an increase in the hydrolysable capacity of lignin collectively. In other words, the termite mechanical chewing process combines with specific biological pretreatment on the lignin counterpart in the plant cell wall, resulting in increased enzymatic cellulose digestibilityin vitro. The specific lignin unlocking mechanism at this chewing stage comprises mainly of the cleavage of specific bonds from the lignin network and the modification and redistribution of functional groups in the resulting chewed plant tissue, which better expose the carbohydrate within the plant cell wall. Moreover, cleavage of the bond between the holocellulosic network and lignin molecule during the chewing process results in much better exposure of the biomass carbohydrate.

Conclusion

Collectively, these data indicate the participation of lignin-related enzyme(s) or polypeptide(s) and/or esterase(s), along with involvement of cellulases and hemicellulases in the chewing process ofC. formosanus, resulting in an efficient pretreatment of biomass through a combination of mechanical and enzymatic processes. This pretreatment could be mimicked for industrial biomass conversion.
Randomised clinical trial of an intensive intervention in the primary care setting of patients with high plasma fibrinogen in the primary prevention of cardiovascular disease
Authors: José Rodríguez Cristóbal Juan , Alonso-Villaverde Grote Carlos , Travé Mercadé Pere , Mª Pérez Santos José , Peña Sendra Esther , Muñoz Lloret Anna , Fernández Pérez Cristina , Bleda Fernández Domingo ,   The EFAP group
Published: March 2012

Background

We have studied the possible effects of an intensive lifestyle change program on plasma fibrinogen levels, in patients with no cardiovascular disease, with elevated levels of fibrinogen, normal cholesterol levels, and a moderate estimated risk of coronary heart disease (CHD) and we have also analysed whether the effect on fibrinogen is independent of the effect on lipids.

Results

This clinical trial was controlled, unblinded and randomized, with parallel groups, done in 13 Basic Health Areas (BHA) in l'Hospitalet de Llobregat (Barcelona) and Barcelona city. The study included 436 patients, aged between 35 and 75 years, with no cardiovascular disease, elevated levels of fibrinogen (> 300 mg/dl), cholesterol < 250 mg/dl, 218 of whom received a more intensive intervention consisting of advice on lifestyle and treatment. The follow-up frequency of the intervention group was every 2 months. The other 218 patients followed their standard care in the BHAs. Fibrinogen, plasma cholesterol and other clinical biochemistry parameters were assessed.

The evaluation of the baseline characteristics of the patients showed that both groups were homogenous. Obesity and hypertension were the most prevalent risk factors. After 24 months of the study, statistically significant changes were seen between the adjusted means of the two groups, for the following parameters: fibrinogen, plasma cholesterol, systolic and diastolic blood pressure and body mass index.

Conclusion

Intensive intervention to achieve lifestyle changes has shown to be effective in reducing some of the estimated CHD factors. However, the effect of intensive intervention on plasma fibrinogen levels did not correlate with the variations in cholesterol.

Trial Registration

ClinicalTrials.gov: NCT01089530
Dead space and CO2 elimination related to pattern of inspiratory gas delivery in ARDS patients
Authors: Aboab Jerome , Niklason Lisbet , Uttman Leif , Brochard Laurent , Jonson Björn
Published: March 2012

Introduction

The inspiratory flow pattern influences CO2 elimination by affecting the time the tidal volume remains resident in alveoli. This time is expressed in terms of mean distribution time (MDT), which is the time available for distribution and diffusion of inspired tidal gas within resident alveolar gas. In healthy and sick pigs, abrupt cessation of inspiratory flow (that is, high end-inspiratory flow (EIF)), enhances CO2 elimination. The objective was to test the hypothesis that effects of inspiratory gas delivery pattern on CO2 exchange can be comprehensively described from the effects of MDT and EIF in patients with acute respiratory distress syndrome (ARDS).

Methods

In a medical intensive care unit of a university hospital, ARDS patients were studied during sequences of breaths with varying inspiratory flow patterns. Patients were ventilated with a computer-controlled ventilator allowing single breaths to be modified with respect to durations of inspiratory flow and postinspiratory pause (TP), as well as the shape of the inspiratory flow wave. From the single-breath test for CO2, the volume of CO2 eliminated by each tidal breath was derived.

Results

A long MDT, caused primarily by a long TP, led to importantly enhanced CO2 elimination. So did a high EIF. Effects of MDT and EIF were comprehensively described with a simple equation. Typically, an efficient and a less-efficient pattern of inspiration could result in ± 10% variation of CO2 elimination, and in individuals, up to 35%.

Conclusions

In ARDS, CO2 elimination is importantly enhanced by an inspiratory flow pattern with long MDT and high EIF. An optimal inspiratory pattern allows a reduction of tidal volume and may be part of lung-protective ventilation.
Teaching the Biological Consequences of Alcohol Abuse through an Online Game: Impacts among Secondary Students
Authors: Klisch Yvonne , Miller Leslie M. , Beier Margaret E. , Wang Shu
Published: March 2012

A multimedia game was designed to serve as a dual-purpose intervention that aligned with National Science Content Standards, while also conveying knowledge about the consequences of alcohol consumption for a secondary school audience. A tertiary goal was to positively impact adolescents' attitudes toward science through career role-play experiences within the game. In a pretest/delayed posttest design, middle and high school students, both male and female, demonstrated significant gains on measures of content knowledge and attitudes toward science. The best predictors of these outcomes were the players' ratings of the game's usability and satisfaction with the game. The outcomes suggest that game interventions can successfully teach standards-based science content, target age-appropriate health messages, and impact students' attitudes toward science.
Molecular Thermodynamics for Cell Biology as Taught with Boxes
Authors: Mayorga Luis S. , López María José , Becker Wayne M.
Published: March 2012

Thermodynamic principles are basic to an understanding of the complex fluxes of energy and information required to keep cells alive. These microscopic machines are nonequilibrium systems at the micron scale that are maintained in pseudo-steady-state conditions by very sophisticated processes. Therefore, several nonstandard concepts need to be taught to rationalize why these very ordered systems proliferate actively all over our planet in seeming contradiction to the second law of thermodynamics. We propose a model consisting of boxes with different shapes that contain small balls that are in constant motion due to a stream of air blowing from below. This is a simple macroscopic system that can be easily visualized by students and that can be understood as mimicking the behavior of a set of molecules exchanging energy. With such boxes, the basic concepts of entropy, enthalpy, and free energy can be taught while reinforcing a molecular understanding of the concepts and stressing the stochastic nature of the thermodynamic laws. In addition, time-related concepts, such as reaction rates and activation energy, can be readily visualized. Moreover, the boxes provide an intuitive way to introduce the role in cellular organization of “information” and Maxwell's demons operating under nonequilibrium conditions.
Exploring Undergraduates' Understanding of Photosynthesis Using Diagnostic Question Clusters
Authors: Parker Joyce M. , Anderson Charles W. , Heidemann Merle , Merrill John , Merritt Brett , Richmond Gail , Urban-Lurain Mark
Published: March 2012

We present a diagnostic question cluster (DQC) that assesses undergraduates' thinking about photosynthesis. This assessment tool is not designed to identify individual misconceptions. Rather, it is focused on students' abilities to apply basic concepts about photosynthesis by reasoning with a coordinated set of practices based on a few scientific principles: conservation of matter, conservation of energy, and the hierarchical nature of biological systems. Data on students' responses to the cluster items and uses of some of the questions in multiple-choice, multiple-true/false, and essay formats are compared. A cross-over study indicates that the multiple-true/false format shows promise as a machine-gradable format that identifies students who have a mixture of accurate and inaccurate ideas. In addition, interviews with students about their choices on three multiple-choice questions reveal the fragility of students' understanding. Collectively, the data show that many undergraduates lack both a basic understanding of the role of photosynthesis in plant metabolism and the ability to reason with scientific principles when learning new content. Implications for instruction are discussed.
Using Science Songs to Enhance Learning: An Interdisciplinary Approach
Authors: Crowther Gregory
Published: March 2012

Music is recognized as an effective mode of teaching young children but is rarely used in university-level science courses. This article reviews the somewhat limited evidence on whether and how content-rich music might affect college students' understanding of science and offers practical suggestions for incorporating music into courses. Aside from aiding memorization, songs may potentially improve learning by helping students feel relaxed and welcome in stressful settings, engaging students through multiple modes (verbal vs. nonverbal) and modalities (auditory vs. visual vs. kinesthetic) simultaneously, challenging students to integrate and “own” the material through the medium of song lyrics, and increasing students' time on task outside of class through enjoyable listening or songwriting assignments. Students may produce content-rich songs of good quality if given sufficient assistance and encouragement by instructors and peers. The challenges ahead include 1) defining the circumstances in which music is most likely to promote learning and 2) developing rubrics for evaluating the quality of songs.
Visualizing Protein Interactions and Dynamics: Evolving a Visual Language for Molecular Animation
Authors: Jenkinson Jodie , McGill Gaël
Published: March 2012

Undergraduate biology education provides students with a number of learning challenges. Subject areas that are particularly difficult to understand include protein conformational change and stability, diffusion and random molecular motion, and molecular crowding. In this study, we examined the relative effectiveness of three-dimensional visualization techniques for learning about protein conformation and molecular motion in association with a ligand–receptor binding event. Increasingly complex versions of the same binding event were depicted in each of four animated treatments. Students (n = 131) were recruited from the undergraduate biology program at University of Toronto, Mississauga. Visualization media were developed in the Center for Molecular and Cellular Dynamics at Harvard Medical School. Stem cell factor ligand and cKit receptor tyrosine kinase were used as a classical example of a ligand-induced receptor dimerization and activation event. Each group completed a pretest, viewed one of four variants of the animation, and completed a posttest and, at 2 wk following the assessment, a delayed posttest. Overall, the most complex animation was the most effective at fostering students' understanding of the events depicted. These results suggest that, in select learning contexts, increasingly complex representations may be more desirable for conveying the dynamic nature of cell binding events.
Sex, Lies, and Paradise: The Assassins, Prester John, and the Fabulation of Civilizational Identities
Authors: Heng Geraldine
Published: March 2012

The Assassins of Alamut are presented in popular media and academic studies as the eleventh-century forerunners of today’s “suicide terrorists,” thus producing a genealogy of spectacular Middle Eastern suicide-homicides that stretches back some nine hundred years. “Sex, Lies, and Paradise” analyzes accretions of stories about the Assassins to see how the Assassins got their name, were believed to anticipate an Islamic paradise in the afterlife, and came to represent for the West a volatile nexus of sex and violence. This effort of literary archeology considers both Eastern and Western fabulations, examining in particular how two popular, widely circulating European texts—Marco Polo’s Travels and Mandeville’s Travels—were key in shaping Western understanding of Islamic history in terms of a civilizational identity that “clashes” with that of the Christian West. The article begins and ends by reflecting on the stakes involved, both today and in the past.
OCTOPUS, a polarly localised membrane-associated protein, regulates phloem differentiation entry in Arabidopsis thaliana
Authors: Truernit Elisabeth , Bauby Hélène , Belcram Katia , Barthélémy Julien , Palauqui Jean-Christophe
Published: March 2012

Vascular development is embedded into the developmental context of plant organ differentiation and can be divided into the consecutive phases of vascular patterning and differentiation of specific vascular cell types (phloem and xylem). To date, only very few genetic determinants of phloem development are known. Here, we identify OCTOPUS (OPS) as a potentiator of phloem differentiation. OPS is a polarly localised membrane-associated protein that is initially expressed in provascular cells, and upon vascular cell type specification becomes restricted to the phloem cell lineage. OPS mutants display a reduction of cotyledon vascular pattern complexity and discontinuous phloem differentiation, whereas OPS overexpressers show accelerated progress of cotyledon vascular patterning and phloem differentiation. We propose that OPS participates in vascular differentiation by interpreting longitudinal signals that lead to the transformation of vascular initials into differentiating protophloem cells.
Fluid flows and forces in development: functions, features and biophysical principles
Authors: Freund Jonathan B. , Goetz Jacky G. , Hill Kent L. , Vermot Julien
Published: March 2012

Throughout morphogenesis, cells experience intracellular tensile and contractile forces on microscopic scales. Cells also experience extracellular forces, such as static forces mediated by the extracellular matrix and forces resulting from microscopic fluid flow. Although the biological ramifications of static forces have received much attention, little is known about the roles of fluid flows and forces during embryogenesis. Here, we focus on the microfluidic forces generated by cilia-driven fluid flow and heart-driven hemodynamics, as well as on the signaling pathways involved in flow sensing. We discuss recent studies that describe the functions and the biomechanical features of these fluid flows. These insights suggest that biological flow determines many aspects of cell behavior and identity through a specific set of physical stimuli and signaling pathways.
Understanding the genetic and molecular pathogenesis of Friedreich’s ataxia through animal and cellular models
Authors: Martelli Alain , Napierala Marek , Puccio Hélène
Published: March 2012

In 1996, a link was identified between Friedreich’s ataxia (FRDA), the most common inherited ataxia in men, and alterations in the gene encoding frataxin (FXN). Initial studies revealed that the disease is caused by a unique, most frequently biallelic, expansion of the GAA sequence in intron 1 of FXN. Since the identification of this link, there has been tremendous progress in understanding frataxin function and the mechanism of FRDA pathology, as well as in developing diagnostics and therapeutic approaches for the disease. These advances were the subject of the 4th International Friedreich’s Ataxia Conference held on 5th–7th May in the Institut de Génétique et de Biologie Moléculaire et Cellulaire, Illkirch, France. More than 200 scientists gathered from all over the world to present the results of research spanning all areas of investigation into FRDA (including clinical aspects, FRDA pathogenesis, genetics and epigenetics of the disease, development of new models of FRDA, and drug discovery). This review provides an update on the understanding of frataxin function, developments of animal and cellular models of the disease, and recent advances in trying to uncover potential molecules for therapy.
Single Molecule Tools Elucidate H2A.Z Nucleosome Composition
Authors: Chen Jiji , Miller Andrew , Kirchmaier Ann L. , Irudayaraj Joseph M. K.
Published: March 2012

Although different epigenetic marks correlate with different chromatin states, how they are integrated within single nucleosomes to generate combinatorial signals remains largely unknown. We report the successful implementation of single molecule tools constituting Fluorescence Correlation Spectroscopy (FCS), Pulse Interleave Excitation-based Forster Resonance Energy Transfer (PIE-FRET) and Fluorescence Lifetime Imaging-based FRET (FLIM-FRET) to elucidate the composition of single nucleosomes containing Htz1p/H2A.Z in vitro and in vivo. We demonstrate yeast nucleosomes containing Htz1p are primarily comprised of H4 K12ac and H3 K4me3 but not H3 K36me3 and these patterns are conserved in mammalian cells. Quantification of epigenetic modifications in nucleosomes will provide a new dimension to epigenetics research and lead to a better understanding of how these patterns contribute to the targeting of chromatin-binding proteins and chromatin structure during gene regulation.
Spatiotemporal Resolution of Mast Cell Granule Exocytosis
Authors: Cohen Roy , Corwith Kathryn , Holowka David , Baird Barbara
Published: March 2012

Mast cell activation initiated by antigen-mediated crosslinking of IgE receptors results in stimulated exocytosis of secretory lysosomes in the process known as degranulation. Much has been learned about the molecular mechanisms important for this process, including the critical role of Ca2+ mobilization, but spatio-temporal relationships between stimulated Ca2+ mobilization and granule exocytosis are incompletely understood. Here we use a novel imaging-based method that utilizes fluorescein isothiocyanate (FITC)-dextran as a reporter for granule exocytosis in RBL mast cells and takes advantage of the pH sensitivity of FITC. We demonstrate the selectivity of FITC-dextran, accumulated by fluid phase uptake, as a marker for secretory lysosomes, and we characterize its capacity to delineate different exocytotic events, including full fusion, kiss-and-run transient fusion, and compound exocytosis. Using this method, we find strong dependence of degranulation kinetics on the duration of cell-substrate attachment. We combine imaging of degranulation and Ca2+ dynamics to demonstrate a spatial relationship between the sites of Ca2+ wave initiation in extended cell protrusions and exocytosis under conditions of limited antigen stimulation. In addition, we find that the spatially proximal Ca2+ signaling and secretory events correlate with participation of TRPC1 channels in Ca2+ mobilization.
Influence of ablative margin on local tumor progression and survival in patients with HCC ≤4 cm after laser ablation
Authors: Francica Giampiero , Petrolati Alesssandra , Di Stasio Enrico , Pacella Sara , Stasi Roberto , Pacella Claudio Maurizio
Published: March 2012

Background

Ablation of the normal hepatic parenchyma surrounding the tumor (ablative margin [AM]) is necessary to prevent local tumor progression.

Purpose

To assess the prognostic value of the ablative margin in patients with HCC ≤4 cm treated with US-guided laser ablation.

Material and Methods

A cohort of 116 patients (53 women and 63 men, age range 42–82 years) with 132 HCC nodules ≤4 cm completely ablated by US-guided laser ablation was retrospectively analyzed. Rates of local tumor progression were compared using different ablative margin cut-offs (≥2.5, 5.0, 7.5, and 10.0 mm). Survival probability curves were obtained with the Kaplan-Meier method.

Results

The mean period of follow-up was 42 months (range 3–114 months). Local tumor progression was identified in 24 out of 132 lesions (18%), with an average time to progression of 24 months (range 6–36 months). A significant difference in local tumor progression was observed only if the ablative margin was ≥7.5 mm (7% vs. 23%, P = 0.020). Survival curves of patients with or without an ablative margin ≥7.5 mm were not different ( P = 0.665; mean survival time 43.8 ± 3.1 and 46.8 ± 6.1 for an AM < or ≥7.5 mm, respectively).

Conclusion

An ablative margin ≥7.5 mm turned out to be useful in preventing local tumor progression but did not affect long-term survival in patients with HCC ≤4 cm treated with laser ablation.
1,25-Dihydroxyvitamin D3 and extracellular inorganic phosphate activate mitogen-activated protein kinase pathway through fibroblast growth factor 23 contributing to hypertrophy and mineralization in osteoarthritic chondrocytes
Authors: Orfanidou Timoklia , Malizos Konstantinos N , Varitimidis Sokratis , Tsezou Aspasia
Published: March 2012

Hypertrophy and impaired mineralization are two processes closely associated with osteoarthritis (OA). 1,25-dihydroxyvitamin D3 (1a,25(OH)2D3) and inorganic phosphate (Pi) are two important factors that are implicated in calcium and phosphate homeostasis of bone metabolism and both can be regulated by the circulating phosphaturic factor fibroblast growth factor 23 (FGF23). The objective of this study was to investigate the role of 1a,25(OH)2D3 and Pi and the molecular mechanism through which they contribute to hypertrophy and mineralization in human osteoarthritic chondrocytes. For this purpose, primary human chondrocytes were obtained from articular cartilage which was collected after total knee replacement surgery in OA patients. FGF23, fibroblast growth factor receptor 1c (FGFR1c), vitamin D3 receptor (VDR), and phosphate inorganic transporter-1 and -2 (PiT-1 and PiT-2) expression levels were evaluated and found to be significantly higher in OA chondrocytes compared with normal. In addition, we observed that the binding of FGF23 to FGFR1c was stronger in OA chondrocytes compared  with normal. Chromatin immunoprecipitation (ChIP) assay revealed, for the first time, the presence of two vitamin D response elements (VDREs) in the FGF23 promoter. Treatment of normal chondrocytes with 1a,25(OH)2D3 or Pi resulted in significant up-regulation of VDR, FGF23, PiT-1, PiT-2 mRNA and protein levels, extracellular signal-regulated kinases 1/2 (ERK1/2) phosphorylation and induction of hypertrophy markers collagen type X (COL10A1), osteopontin (OPN), osteocalcin (OC), catabolic markers metalloproteinase-13 (MMP-13) and the apoptotic marker caspase-9. Furthermore, VDR silencing in OA chondrocytes negatively regulated FGF23, COL10A1, OPN, OC, MMP-13 and caspase-9 expressions and ERK1/2 phosphorylation. Finally, combined VDR silencing and PiT-1, PiT-2 inhibition in OA chondrocytes resulted in additive down-regulation of FGF23 expression, ERK1/2 activation and COL10A1, OPN, OC, MMP-13 and caspase-9 expression levels. We propose that 1a,25(OH)2D3 and Pi act synergistically through FGF23 signaling and ERK1/2 phosphorylation contributing to late hypertrophic events and impaired mineralization in osteoarthritic chondrocytes.