bluuebunny/crossref_metadata_2025 huggingface dataset:
Noninvasive Evaluation of Coronary Sinus Anatomy and Its Relation to the Mitral Valve Annulus
Authors: Tops Laurens F. , Van de Veire Nico R. , Schuijf Joanne D. , de Roos Albert , van der Wall Ernst E. , Schalij Martin J. , Bax Jeroen J.
Published: March 2007

Background—

Percutaneous mitral annuloplasty has been proposed as an alternative to surgical annuloplasty. In this respect, evaluation of the coronary sinus (CS) and its relation with the mitral valve annulus (MVA) and the coronary arteries is relevant. The feasibility of evaluating these issues noninvasively with multislice computed tomography was determined.

Methods and Results—

In 105 patients (72 men, age 59±11 years), 64-slice multislice computed tomography was performed for noninvasive evaluation of coronary artery disease. Thirty-four patients with heart failure and/or severe mitral regurgitation were included. Three-dimensional reconstructions and standard orthogonal planes were used to assess CS anatomy and its relation with the MVA and circumflex artery. In 71 patients (68%), the circumflex artery coursed between the CS and the MVA with a minimal distance between the CS and the circumflex artery of 1.3±1.0 mm. The CS was located along the left atrial wall, rather than along the MVA, in the majority of the patients (ranging from 90% at the level of the MVA to 14% at the level of the distal CS). The minimal distance between the CS and MVA was 5.1±2.9 mm. In patients with severe mitral regurgitation, the minimal distance between the CS and the MVA was significantly greater as compared with patients without severe mitral regurgitation (mean 7.3±3.9 mm versus 4.8±2.5 mm,
P
<0.05).

Conclusion—

In the majority of the patients, the CS courses superiorly to the MVA. In 68% of the patients, the circumflex artery courses between the CS and the mitral annulus. Multislice computed tomography may provide useful information for the selection of potential candidates for percutaneous mitral annuloplasty.
Renal Albumin Excretion
Authors: Rao Fangwen , Wessel Jennifer , Wen Gen , Zhang Lian , Rana Brinda K. , Kennedy Brian P. , Greenwood Tiffany A. , Salem Rany M. , Chen Yuqing , Khandrika Srikrishna , Hamilton Bruce A. , Smith Douglas W. , Holstein-Rathlou Niels-Henrik , Ziegler Michael G. , Schork Nicholas J. , O’Connor Daniel T.
Published: March 2007

Albumin excretion marks early glomerular injury in hypertension. This study investigated heritability of albumin excretion in twin pairs and its genetic determination by adrenergic pathway polymorphism. Genetic associations used single nucleotide polymorphisms at adrenergic pathway loci spanning catecholamine biosynthesis, storage, catabolism, receptor action, and postreceptor signal transduction. We studied 134 single nucleotide polymorphisms at 46 loci for a total of >51 000 genotypes. Albumin excretion heritability was 45.2±7.4% (
P
=2×10
−7
), and the phenotype aggregated significantly with adrenergic, renal, metabolic, and hemodynamic traits. In the adrenergic system, excretions of both norepinephrine and epinephrine correlated with albumin. In the kidney, albumin excretion correlated with glomerular and tubular traits (Na
+
and K
+
excretion; fractional excretion of Na
+
and Li
+
). Albumin excretion shared genetic determination (genetic covariance) with epinephrine excretion, and environmental determination with glomerular filtration rate and electrolyte intake/excretion. Albumin excretion associated with polymorphisms at multiple points in the adrenergic pathway: catecholamine biosynthesis (tyrosine hydroxylase), catabolism (monoamine oxidase A), storage/release (chromogranin A), receptor target (dopamine D1 receptor), and postreceptor signal transduction (sorting nexin 13 and rho kinase). Epistasis (gene-by-gene interaction) occurred between alleles at rho kinase, tyrosine hydroxylase, chromogranin A, and sorting nexin 13. Dopamine D1 receptor polymorphism showed pleiotropic effects on both albumin and dopamine excretion. These studies establish new roles for heredity and environment in albumin excretion. Urinary excretions of albumin and catecholamines are highly heritable, and their parallel suggests adrenergic mediation of early glomerular permeability alterations. Albumin excretion is influenced by multiple adrenergic pathway genes and is, thus, polygenic. Such functional links between adrenergic activity and glomerular injury suggest novel approaches to its prediction, prevention, diagnosis, and treatment.
To Dip or Not to Dip
Authors: Sayk Friedhelm , Becker Christoph , Teckentrup Christina , Fehm Horst-Lorenz , Struck Jan , Wellhoener Jens Peter , Dodt Christoph
Published: March 2007

That sleep is accompanied by a blood pressure decrease is well known; however, the underlying physiology deserves further investigation. The present study examines in healthy subjects 2 main questions: is this dipping actively evoked? and what are the consequences of nondipping for daytime blood pressure? Nocturnal blood pressure was extrinsically elevated in 12 sleeping subjects to mean daytime values by continuously infused phenylephrine. This nondipping significantly lowered morning blood pressure during rest and 3 hours after resuming physical activity compared with a control condition (isotonic saline). Neither muscle sympathetic nerve activity nor sensitivity of α-adrenoceptors was reduced. However, the set point for initiation of regulatory responses through the baroreflex was clearly shifted toward lower blood pressure levels. Our results support the hypothesis of an actively regulated central mechanism for blood pressure resetting and set point consolidation of the baroreflex during nighttime sleep. This is suggested by the fact that extrinsically induced nondipping induces sustained decrease in blood pressure during the following morning through an actively lowered baroreflex set point.
Cerebral Hemodynamics After Short- and Long-Term Reduction in Blood Pressure in Mild and Moderate Hypertension
Authors: Zhang Rong , Witkowski Sarah , Fu Qi , Claassen Jurgen A.H.R. , Levine Benjamin D.
Published: March 2007

This study tested the hypothesis that acute reduction in blood pressure (BP) at the initial stage of antihypertensive therapy compromises brain perfusion and dynamic cerebral autoregulation in patients with hypertension. Cerebral blood flow velocity and BP were measured in patients with mild and moderate hypertension and in healthy volunteers at baseline upon reduction of BP within 1 to 2 weeks of administration of losartan/hydrochlorothiazide and after 3 to 4 months of treatment. The transfer function between beat-to-beat changes in BP and cerebral blood flow velocity was estimated to assess dynamic autoregulation. After 1 to 2 weeks of treatment, BP was reduced in mild (143±7/88±4 versus 126±12/77±6 mm Hg) and moderate hypertension (163±11/101±9 versus 134±17/84±9 mm Hg;
P
<0.05). These reductions in BP were well maintained over the 3 to 4 month period. Cerebral blood flow velocity did not change, whereas cerebrovascular resistance index was reduced by 17% (
P
<0.05) after reduction in BP. Responses of cerebral blood flow velocity to head-up tilt remained unchanged. Baseline transfer function gain at the low frequencies (0.07 to 0.20 Hz) was reduced in moderate hypertension, consistent with cerebral vasoconstriction and/or enhanced dynamic autoregulation. However, this reduced transfer function gain was restored to the level of control subjects after reduction in BP. These findings, contrary to our hypothesis, demonstrate that there is a rapid adaptation of the cerebral vasculature to protect the brain from hypoperfusion even at the initial stage of antihypertensive therapy in patients with mild and moderate hypertension.
Peroxisome Proliferator-Activated Receptor α–Independent Actions of Fenofibrate Exacerbates Left Ventricular Dilation and Fibrosis in Chronic Pressure Overload
Authors: Duhaney Toni-Ann S. , Cui Lei , Rude Mary K. , Lebrasseur Nathan K. , Ngoy Soeun , De Silva Deepa S. , Siwik Deborah A. , Liao Ronglih , Sam Flora
Published: March 2007

Progressive cardiac remodeling is characterized by subsequent chamber hypertrophy, enlargement, and pump dysfunction. It is also associated with increased cardiac fibrosis and matrix turnover. Interestingly, peroxisome proliferator-activated receptor (PPAR) α activators reduce cardiac hypertrophy, inflammation, and fibrosis. Little is known about the role of fenofibrates in mediating PPARα-independent effects in response to chronic pressure overload (PO). Wild-type and PPARα-deficient mice were subjected to chronic PO caused by ascending aortic constriction to test the role of fenofibrates in chronic, progressive cardiac remodeling by a PPARα-independent mechanism. Mice were randomized to regular chow or chow-containing fenofibrate (100 mg/kg of body weight per day) for 1 week before and 8 weeks after ascending aortic constriction. In the presence of PPARα, wild-type chronic PO mice, treated with fenofibrate, had improved cardiac remodeling. However, PO PPARα-deficient mice treated with fenofibrate had increased mortality, significantly adverse left ventricular end diastolic (3.4±0.1 versus 4.2±0.1 mm) and end systolic (1.5±0.2 versus 2.5±0.2 mm) dimensions, and fractional shortening (57±3% versus 40±3%). Fenofibrate also increased myocardial hypertrophy, cardiac fibrosis, and the ratio of matrix metalloproteinase-2/tissue inhibitor of matrix metalloproteinase-2 in PO PPARα-deficient mice. Fenofibrate inhibited matrix metalloproteinase activity in vitro and aldosterone-induced increases in extracellular signal-regulated kinase phosphorylation. Thus, fenofibrate improved cardiac remodeling in chronic PO mice. However, in PPARα-deficient mice, this chronic PO was exacerbated and associated with increased myocardial fibrosis and altered matrix remodeling. In the absence of PPARα, fenofibrates exerts deleterious, pleiotropic myocardial actions. This is an important observation, because PPARα agonists are considered possible inhibitory regulators of cardiac remodeling in the remodeled heart.
Synchronization Phenomena in Surface-Reaction Models of Protocells
Authors: Serra Roberto , Carletti Timoteo , Poli Irene
Published: March 2007

A class of generic models of protocells is introduced, which are inspired by the Los Alamos bug hypothesis but which, due to their abstraction level, can be applied to a wider set of detailed protocell hypotheses. These models describe the coupled growth of the lipid container and of the self-replicating molecules. A technique to analyze the dynamics of populations of such protocells is described, which couples a continuous-time formalism for the growth between two successive cell divisions, and a discrete map that relates the quantity of self-replicating molecules in successive generations. This technique allows one to derive several properties in an analytical way. It is shown that, under fairly general assumptions, the two growth rates synchronize, so that the lipid container doubles its size when the number of self-replicating molecules has also doubled—thus giving rise to exponential growth of the population of protocells. Such synchronization had been postulated a priori in previous models of protocells; here it is an emergent property. We also compare the rate of duplication of two populations generated by two different protocells with different kinds of self-replicating molecules, considering the interesting case where the rate of self-replication of one kind is higher than that of the other, but its contribution to the container growth rate is smaller. It is shown that in this case the population of offspring of the protocell with the faster-replicating molecule will eventually grow faster than the other. The case where two different types of self-replicating monomers are present in the same protocell is also analyzed, and it is shown that, if the replication follows a first-order kinetic equation, then the faster replicator eventually displaces the slower one, whereas if the growth is sublinear the two coexist. It is also proven by an appropriate rescaling of time that the results that concern the system asymptotic dynamics hold both for micelles and vesicles.
An Artificial Ecosystem: Emergent Dynamics and Lifelike Properties
Authors: Rönkkö Mauno
Published: March 2007

We discuss modeling and analysis of an artificial ecosystem. The ecosystem consists of basic elements, scents, plants, and animals. There are two species of animals: worms and beetles. As beetles absorb energy from worms, which absorb energy from blades of grass, which absorb energy from water, there is a food chain connecting animals to basic elements. The novelty of our approach lies in the modeling technique: we model the entire ecosystem using a single particle system. Consequently, the physical interaction dynamics not only shows emergent dynamics, but also some interesting lifelike properties. As the main contribution, we formalize the particle system and use it to model and analyze the ecosystem. We consider here several scenarios with nontrivial interaction dynamics.
Questioning in Chinese University EL Classrooms
Authors: Tan Zhi
Published: March 2007

This paper reports the findings of a study examining classroom questioning behavior and its impacts on students' development. A triangulation was conducted to collect data: observations of nine university English lessons, semi-structured interviews with six teachers and focus group discussions with three groups of students.

The data showed that many of the questions asked were lower cognitive questions and that they were mostly answered in chorus or by teacher nomination. The findings revealed that questioning was employed by the teachers to check text comprehension, hold the students' attention on the texts, to enhance and protect teacher's and students' face, to maintain classroom discipline, to establish teacher authority, and to gain student respect and acceptance.

The results indicate that the questioning behavior identified is likely to have potential negative impact on the students. Tentative suggestions are made for improving questioning style to fit the Chinese educational reform agenda.
Investigating Group Planning in Preparation for Oral Presentations in an EFL Class in Vietnam
Authors: Tuan Truong Anh , Neomy Storch
Published: March 2007

Research on pre-task planning has shown that planning has beneficial effects on learners' subsequent language output. However, to date most of this research has focused on solitary rather than group planning. Furthermore, very few studies have investigated what actually happens during the planning time. This study, conducted in an EFL class in Vietnam, investigated the nature and impact of group planning on learners' subsequent individual oral presentations. The learners (n=17) worked in small groups preparing for oral presentations. At the end of the planning session, two learners from each group were randomly selected to give presentations. All group work and individual presentations were audio recorded and teacher observation notes were collected. Transcribed oral data were coded for idea units and language related episodes as well as salient features of group interaction. The study found that group planning dealt with the content rather than the language of presentations. Using a matching procedure, the study found that most of the ideas presented were generated during the planning time. However, there were variations between the groups. The group that seemed to be the most interactive and that focused on both content and language was a group composed of mixed proficiency learners.
Before You Open the Doors
Authors: Lane Jodi , Lanza-Kaduce Lonn
Published: March 2007

In 2003, the Office of Juvenile Justice and Delinquency Prevention (OJJDP) provided Florida's Department of Juvenile Justice (DJJ) with a $3.5 million grant to design and implement a faith- and community-based program for incarcerated juveniles. Florida's experience developing a completely new program has provided valuable lessons regarding important issues to consider and address before clients are referred to the program. This article enumerates 10 key lessons from Florida's experience that can provide important guidance to other sites across the country hoping to develop faith-related services for youths in institutions.
Islam and Democracy from Tahtawi to Ghannouchi
Authors: Tamimi Azzam
Published: March 2007

This article explores the development of Islamic democratic thought over the past two centuries. Triggered by the European encroachment on Muslim lands and fueled by a sense of frustration precipitated by centuries of decline and backwardness, democracy continues to be a controversial concept seen by some Islamists as the therapy for Muslim sickness and by others as the illness itself. The main cause of the disagreement has been the definition of the concept: those that defend it see it as a set of procedures aimed at curbing the tendency to abuse political power and those that reject it see it as a philosophy that undermines the Islamic faith and threatens the Islamic way of life. The article argues that, even though the intellectual debate has to a large extent been settled in favour of the defenders of democracy, the main obstacle hindering democratization in Muslim lands continues to be an external one.
Cultural-economy and cities
Authors: Amin Ash , Thrift Nigel
Published: March 2007

This article seeks to re-imagine the urban economy from a cultural-economy perspective. The first part summarizes a perspective arguing that economic life is so shot through with cultural inputs and practices at all levels that ‘culture’ and ‘economy’ cannot be seen as separate entities. Focusing on the power of such influences as passion, moral values, soft knowledge, trust and cultural metaphor, the article illustrates different ways in which the economy can be imagined only as a hybrid entanglement. The second part uses the insight gained to illustrate how the urban is implicated in narrating new economic mantras as well as supporting and defining the everyday cultural-economy. The purpose of this illustration is to reveal new ways in which the urban economy might be grasped.
Humboldt's compromise, or the forgotten geographies of landscape
Authors: Minca Claudio
Published: March 2007

This paper is about the strategic forgetting of the Humboldtian ‘compromise’. The analysis looks to the ways in which the concept of landscape entered geography as a device uniquely able to match the Romantic imaginary of the emergent European bourgeoisie and this latter's need for a scientific (and a-political) theory of knowledge. Humboldt's geographical idea of landscape was precisely the ‘compromise’ that would provide the bourgeoisie with a new spatial theory. What I claim in this paper, following Franco Farinelli's critical rewriting of the history of European geography, is that the nature of Humboldt's attempt has been essentially cancelled from canonical disciplinary accounts, for a number of historical-political reasons. This accounts for why, even today, despite the achievements of the new cultural geography and the influence of nonrepresentational theories, landscapes all too often continue to be read either as texts or, worse still, as ‘real’ spaces and/or built environments.
Optimal solid waste collection routes identified by the ant colony system algorithm
Authors: Karadimas Nikolaos V. , Papatzelou Katerina , Loumos Vassili G.
Published: March 2007

In the present paper, the Ant Colony System (ACS) algorithm is used for the identification of optimal routes in the case of municipal solid waste (MSW) collection. The proposed MSW management system is based on a geo-referenced spatial database supported by a geographic information system (GIS). The GIS takes into account all the required parameters for solid waste collection. These parameters include static and dynamic data, such as the positions of waste bins, the road network and the related traffic, as well as the population density in the area under study. In addition, waste collection schedules, truck capacities and their characteristics are also taken into consideration. Spatio-temporal statistical analysis is used to estimate inter-relations between dynamic factors, like network traffic changes in residential and commercial areas. The user, in the proposed system, is able to define or modify all of the required dynamic factors for the creation of alternative initial scenarios. The objective of the system is to identify the most cost-effective scenario for waste collection, to estimate its running cost and to simulate its application. Finally, the results of the ACS algorithm are compared with the empirical method currently used by the Municipality of Athens.
Recycling of aged refuse from a closed landfill
Authors: Zhao Youcai , Song Liyan , Huang Renhua , Song Lijie , Li Xiong
Published: March 2007

In this study, refuse excavated from a typical refuse landfill in Shanghai after 8-10 years of placement was characterized in terms of particle size, total nitrogen, total phosphorus, and biodegradable matter. The refuse contained a large and diverse population of micro-organisms with a high capacity for decomposing refractory organic matter present in some waste-waters, including leachate. It was found that the aged refuse was quite stable after about a decade of decomposition in the warm, humid climate of southern China. The fine fractions resembled and had the properties of black soil, a medium that is suitable for green construction, organic fertilizer, or as bio-reactor media for biological treatment of organic wastewaters. Excavation of the aged refuse would make about 50% of the space available for fresh refuse. The plastics, glass, textiles, and cans can be readily mechanically separated and recycled after cleaning. It is estimated that at least 200 millions tonnes of such aged refuse are available in China alone, and at least 10 times that much is buried worldwide. Hence, the evaluation of mined landfill waste and consideration of its potential uses is of great significance.
Assessment of municipal solid waste compost quality using standardized methods before preparation of plant growth media
Authors: Silva María Teresa Barral , Menduíña Ana Moldes , Seijo Yolanda Cendón , Viqueira Francisco Díaz-Fierros
Published: March 2007

The quality of compost and its suitability for agricultural application depend upon physical and chemical parameters such as water-holding capacity, porosity, pH, electrical conductivity, C/N ratio, available nutrients and the absence of toxic substances. In the present study a complete characterization of an industrial municipal solid waste compost (MSWC) based on standardized European methods (CEN) for soil improvers and growing media was obtained, and compared with the quality of other Spanish composted biowaste and conventional substrates such as peat and pine bark. The MSWC was obtained from the main composting plant in Galicia (Spain), which processes organic waste that has been separated at origin and collected from more than 100 000 inhabitants. The MSWC presented a lower C/N ratio (15) than peat (84) and composted pine bark (CPB) (211), but had a similar ratio to other marketed MSWC. The nutrients and heavy metals were extracted using different recommended solvents (water, CaCl2 + diethylen triamin pentaacetic acid, and aqua regia). The nutrient concentrations of composted urban waste or manure were much higher than those of peat, CPB or pine bark. On the basis of the results of the plant tolerance test, the MSWC could be employed directly as a soil improver, but would need to be diluted with other low-salt components such as peat or CPB before being used as a growing media.
Hysteretic Behavior of Magnetorheological Fluid and Identification Using Preisach Model
Authors: Han Young-Min , Choi Seung-Bok , Wereley Norman M.
Published: March 2007

This study examines the field-dependent hysteretic behavior of a magnetorheological (MR) fluid and its identification using a Preisach model. The field-dependent shear stress of a commercially available MR fluid is measured using a parallel disk rheometer, and its shear stress versus shear rate hysteretic behavior is measured. To demonstrate the applicability of the Preisach model to MR fluid hysteresis modeling, two significant properties are empirically studied; the minor loop property and the wiping-out property. Using these data, the Preisach model for the MR fluid is identified using experimental first order descending curves. The effectiveness of the identified hysteresis model is verified in the time domain by comparing the reconstructed to the measured field-dependent shear stress. In addition, the identified hysteresis is compared to the conventional Bingham model.
Optimization of Piezoelectric Actuator Configuration on a Flexible Fin for Vibration Control using Genetic Algorithms
Authors: Rader Andrew A. , Afagh Fred F. , Yousefi-Koma Aghil , Zimcik David G.
Published: March 2007

This study presents a novel approach to optimizing the configuration of piezoelectric actuators for vibration control of a flexible aircraft fin. The fitness (cost) function for optimization using a genetic algorithm is derived directly from the frequency response function (FRF) obtained from a finite element model of the fin. In comparison to existing approaches, this method allows optimization on much more complex geometries where the derivation of an analytical fitness function is prohibitive or impossible. This technique is applied to two optimization problems for vibration control of the fin. First, the position of a single actuator is optimized anywhere within a judiciously pre-determined area of the fin using a genetic algorithm for polynomial surface fitting of the FRF in order to obtain a continuous fitness function. Next, the configuration of a pre-determined number of up to 48 separate actuators is optimized within the same area. The optimization approach is verified against experimental results obtained from a set of 12 actuators fixed to an experimental model of the fin.
The (Hetero)Sexualization of the Military and the Militarization of (Hetero)Sex: Discourses on Male (Hetero)Sexual Practices among a Group of Young Men in the South African Military
Authors: Shefer Tamara , Mankayi Nyameka
Published: March 2007

The article is framed in the context of the challenge of HIV/AIDS in South Africa and recognizes that military men are particularly vulnerable to infection. This is argued on the basis of their specific contexts of mobility, isolation and being among communities where they have greater economic and political power, as well as in relation to their identities and sexualities as men, and how these are exaggerated by the institutional framework of the military. Drawing on data from a larger study exploring a group of military men's narratives on their masculinity, sexuality, sexual relationships and HIV/AIDS, the discussion is presented in four broad thematic areas. These point to core aspects of the dominant construction of male sexualities in the military and the complex intersection of hegemonic masculinities and military masculinities, which facilitate a particular vulnerability to unsafe sexual practices. The article concludes with a recommendation that tackling HIV in the military needs to involve rigorous examination of how constructions of masculinity in the military context, at the level of material conditions and in terms of normative discourses on what it means to be a man in the military, exert specific pressures on men to adhere to traditional models of being a man with their attendant sexual practices.
Cytokine-independent growth and clonal expansion of a primary human CD8+ T-cell clone following retroviral transduction with the IL-15 gene
Authors: Hsu Cary , Jones Stephanie A. , Cohen Cyrille J. , Zheng Zhili , Kerstann Keith , Zhou Juhua , Robbins Paul F. , Peng Peter D. , Shen Xinglei , Gomes Theotonius J. , Dunbar Cynthia E. , Munroe David J. , Stewart Claudia , Cornetta Kenneth , Wangsa Danny , Ried Thomas , Rosenberg Steven A. , Morgan Richard A.
Published: March 2007

Malignancies arising from retrovirally transduced hematopoietic stem cells have been reported in animal models and human gene therapy trials. Whether mature lymphocytes are susceptible to insertional mutagenesis is unknown. We have characterized a primary human CD8+ T-cell clone, which exhibited logarithmic ex vivo growth in the absence of exogenous cytokine support for more than 1 year after transduction with a murine leukemia virus–based vector encoding the T-cell growth factor IL-15. Phenotypically, the clone was CD28−, CD45RA−, CD45RO+, and CD62L−, a profile consistent with effector memory T lymphocytes. After gene transfer with tumor-antigen–specific T-cell receptors, the clone secreted IFN-γ upon encountering tumor targets, providing further evidence that they derived from mature lymphocytes. Gene-expression analyses revealed no evidence of insertional activation of genes flanking the retroviral insertion sites. The clone exhibited constitutive telomerase activity, and the presence of autocrine loop was suggested by impaired cell proliferation following knockdown of IL-15Rα expression. The generation of this cell line suggests that nonphysiologic expression of IL-15 can result in the long-term in vitro growth of mature human T lymphocytes. The cytokine-independent growth of this line was a rare event that has not been observed in other IL-15 vector transduction experiments or with any other integrating vector system. It does not appear that the retroviral vector integration sites played a role in the continuous growth of this cell clone, but this remains under investigation.
Gene expression profiling of human mesenchymal stem cells derived from bone marrow during expansion and osteoblast differentiation
Authors: Kulterer Birgit , Friedl Gerald , Jandrositz Anita , Sanchez-Cabo Fatima , Prokesch Andreas , Paar Christine , Scheideler Marcel , Windhager Reinhard , Preisegger Karl-Heinz , Trajanoski Zlatko
Published: March 2007

Background

Human mesenchymal stem cells (MSC) with the capacity to differentiate into osteoblasts provide potential for the development of novel treatment strategies, such as improved healing of large bone defects. However, their low frequency in bone marrow necessitate ex vivo expansion for further clinical application. In this study we asked if MSC are developing in an aberrant or unwanted way during ex vivo long-term cultivation and if artificial cultivation conditions exert any influence on their stem cell maintenance. To address this question we first developed human oligonucleotide microarrays with 30.000 elements and then performed large-scale expression profiling of long-term expanded MSC and MSC during differentiation into osteoblasts.

Results

The results showed that MSC did not alter their osteogenic differentiation capacity, surface marker profile, and the expression profiles of MSC during expansion. Microarray analysis of MSC during osteogenic differentiation identified three candidate genes for further examination and functional analysis: ID4, CRYAB, and SORT1. Additionally, we were able to reconstruct the three developmental phases during osteoblast differentiation: proliferation, matrix maturation, and mineralization, and illustrate the activation of the SMAD signaling pathways by TGF-β2 and BMPs.

Conclusion

With a variety of assays we could show that MSC represent a cell population which can be expanded for therapeutic applications.
Pulsed-field gel electrophoresis profile homogeneity of Mycobacterium avium subsp. paratuberculosis isolates from cattle and heterogeneity of those from sheep and goats
Authors: Sevilla Iker , Garrido Joseba M , Geijo Marivi , Juste Ramon A
Published: March 2007

Background

Mycobacterium avium subsp. paratuberculosis (Map) causes paratuberculosis in animals and is suspected of causing Crohn's Disease in humans. Characterization of strains led to classify paratuberculosis isolates in two main types, cattle type strains, found affecting all host species, and sheep type strains, reported affecting mainly sheep. In order to get a better understanding of the epidemiology of paratuberculosis a large set of Map isolates obtained from different species over the last 25 years have been characterized. Five-hundred and twenty isolates from different hosts (cattle, sheep, goats, bison, deer and wild boar) and origins had been cultured and typed by IS1311 restriction-endonuclease-analysis. Two-hundred and sixty-nine isolates were further characterized by pulsed-field gel electrophoresis (PFGE) using Sna BI and Spe I endonucleases. Differences in strain isolation upon various media conditions were also studied.

Results

All bovines, 4 and 26% of Spanish sheep and goats, respectively, and the deer and wild boar studied, carried IS1311-Cattle type strains. IS1311-Sheep type encompassed 96% and 74% of Spanish sheep and goats, and all three Portuguese sheep. Thirty-seven distinct multiplex PFGE profiles were found, giving 32 novel profiles. Profiles 2-1 and 1-1 accounted for the 85% of cattle isolates. Ten distinct profiles were detected in Spanish sheep, none of them with an incidence higher than 25%. Profile 16-11 (43%) and another three profiles were identified in Spanish caprine cultures. The hierarchical analysis, clustered all profiles found in cattle, "wild" hosts and some small ruminants within the same group. The other group included 11 profiles only found in Spanish sheep and goats, including Spanish pigmented profiles. Differences in growth requirements associated with isolate genotype were observed.

Conclusion

Cattle in Spain are infected with cattle type strains, while sheep and goats are mainly infected with sheep type strains. Although 7H9 broth based culture media seem to broadly cover the growth requirements of most Map strains, the use of various solid media is recommended to reduce any recovery biases. High genetic homogeneity of isolates from cattle, and heterogeneity of those from sheep and goats have been detected.
Artesunate – amodiaquine combination therapy for falciparum malaria in young Gabonese children
Authors: Oyakhirome Sunny , Pötschke Marc , Schwarz Norbert G , Dörnemann Jenny , Laengin Matthias , Salazar Carmen Ospina , Lell Bertrand , Kun Jürgen FJ , Kremsner Peter G , Grobusch Martin P
Published: March 2007

Background

Artesunate-amodiaquine combination for the treatment of childhood malaria is one of the artemisinin combination therapies (ACTs) recommended by National authorities in many African countries today. Effectiveness data on this combination in young children is scarce.

Methods

The effectiveness of three daily doses of artesunate plus amodiaquine combination given unsupervised (n = 32), compared with the efficacy when given under full supervision (n = 29) to children with falciparum malaria were assessed in an unrandomized study.

Results

61 patients analysed revealed a PCR-corrected day-28 cure rate of 86 % (25 of 29 patients; CI 69 – 95 %) in the supervised group and 63 % (20 of 32 patients; CI 45 – 77 %) in the unsupervised group. The difference in outcome between both groups was statistically significant (p = 0.04). No severe adverse events were reported.

Conclusion

The effectiveness of this short course regimen in young children with falciparum malaria could be augmented by increased adherence and improved formulation.
Mid-term echocardiographic follow up of left ventricular function with permanent right ventricular pacing in pediatric patients with and without structural heart disease
Authors: Shalganov Tchavdar Nikolov , Paprika Dora , Vatasescu Radu , Kardos Attila , Mihalcz Attila , Kornyei Laszlo , Szatmari Andras , Szili-Torok Tamas
Published: March 2007

Background

Chronic right ventricular apical pacing may have detrimental effect on left ventricular function and may promote to heart failure in adult patients with left ventricular dysfunction.

Methods

A group of 99 pediatric patients with previously implanted pacemaker was studied retrospectively. Forty-three patients (21 males) had isolated congenital complete or advanced atrioventricular block. The remaining 56 patients (34 males) had pacing indication in the presence of structural heart disease. Thirty-two of them (21 males) had isolated structural heart disease and the remaining 24 (13 males) had complex congenital heart disease. Patients were followed up for an average of 53 ± 41.4 months with 12-lead electrocardiogram and transthoracic echocardiography. Left ventricular shortening fraction was used as a marker of ventricular function. QRS duration was assessed using leads V5 or II on standard 12-lead electrocardiogram.

Results

Left ventricular shortening fraction did not change significantly after pacemaker implantation compared to preimplant values overall and in subgroups. In patients with complex congenital heart malformations shortening fraction decreased significantly during the follow up period. (0.45 ± 0.07 vs 0.35 ± 0.06, p = 0.015). The correlation between the change in left ventricular shortening fraction and the mean increase of paced QRS duration was not significant. Six patients developed dilated cardiomyopathy, which was diagnosed 2 months to 9 years after pacemaker implantation.

Conclusion

Chronic right ventricular pacing in pediatric patients with or without structural heart disease does not necessarily result in decline of left ventricular function. In patients with complex congenital heart malformations left ventricular shortening fraction shows significant decrease.
Conserved aspartic acid 233 and alanine 231 are not required for poliovirus polymerase function in replicons
Authors: Freistadt Marion S , Eberle Karen E
Published: March 2007

Nucleic acid polymerases have similar structures and motifs. The function of an aspartic acid (conserved in all classes of nucleic acid polymerases) in motif A remains poorly understood in RNA-dependent RNA polymerases. We mutated this residue to alanine in a poliovirus replicon. The resulting mutant could still replicate, although at a reduced level. In addition, mutation A231C (also in motif A) yielded high levels of replication. Taken together these results show that poliovirus polymerase conserved residues D233 and A231 are not essential to poliovirus replicon function.
A pilot study of IL-1 inhibition by anakinra in acute gout
Authors: So Alexander , De Smedt Thibaut , Revaz Sylvie , Tschopp Jürg
Published: March 2007

Monosodium urate crystals stimulate monocytes and macrophages to release IL-1β through the NALP3 component of the inflammasome. The effectiveness of IL-1 inhibition in hereditary autoinflammatory syndromes with mutations in the NALP3 protein suggested that IL-1 inhibition might also be effective in relieving the inflammatory manifestations of acute gout. The effectiveness of IL-1 inhibition was first evaluated in a mouse model of monosodium urate crystal-induced inflammation. IL-1 inhibition prevented peritoneal neutrophil accumulation but TNF blockade had no effect. Based on these findings, we performed a pilot, open-labeled study (trial registration number ISRCTN10862635) in 10 patients with gout who could not tolerate or had failed standard antiinflammatory therapies. All patients received 100 mg anakinra daily for 3 days. All 10 patients with acute gout responded rapidly to anakinra. No adverse effects were observed. IL-1 blockade appears to be an effective therapy for acute gouty arthritis. The clinical findings need to be confirmed in a controlled study.
Computer simulation allows goal-oriented mechanical ventilation in acute respiratory distress syndrome
Authors: Uttman Leif , Ögren Helena , Niklason Lisbet , Drefeldt Björn , Jonson Björn
Published: March 2007

Introduction

To prevent further lung damage in patients with acute respiratory distress syndrome (ARDS), it is important to avoid overdistension and cyclic opening and closing of atelectatic alveoli. Previous studies have demonstrated protective effects of using low tidal volume (VT), moderate positive end-expiratory pressure and low airway pressure. Aspiration of dead space (ASPIDS) allows a reduction in VT by eliminating dead space in the tracheal tube and tubing. We hypothesized that, by applying goal-orientated ventilation based on iterative computer simulation, VT can be reduced at high respiratory rate and much further reduced during ASPIDS without compromising gas exchange or causing high airway pressure.

Methods

ARDS was induced in eight pigs by surfactant perturbation and ventilator-induced lung injury. Ventilator resetting guided by computer simulation was then performed, aiming at minimal VT, plateau pressure 30 cmH2O and isocapnia, first by only increasing respiratory rate and then by using ASPIDS as well.

Results

VT decreased from 7.2 ± 0.5 ml/kg to 6.6 ± 0.5 ml/kg as respiratory rate increased from 40 to 64 ± 6 breaths/min, and to 4.0 ± 0.4 ml/kg when ASPIDS was used at 80 ± 6 breaths/min. Measured values of arterial carbon dioxide tension were close to predicted values. Without ASPIDS, total positive end-expiratory pressure and plateau pressure were slightly higher than predicted, and with ASPIDS they were lower than predicted.

Conclusion

In principle, computer simulation may be used in goal-oriented ventilation in ARDS. Further studies are needed to investigate potential benefits and limitations over extended study periods.
Repetitive DNA is associated with centromeric domains in Trypanosoma brucei but not Trypanosoma cruzi
Authors: Obado Samson O , Bot Christopher , Nilsson Daniel , Andersson Bjorn , Kelly John M
Published: March 2007

Background

Trypanosomes are parasitic protozoa that diverged early from the main eukaryotic lineage. Their genomes display several unusual characteristics and, despite completion of the trypanosome genome projects, the location of centromeric DNA has not been identified.

Results

We report evidence on the location and nature of centromeric DNA in Trypanosoma cruzi and Trypanosoma brucei. In T. cruzi, we used telomere-associated chromosome fragmentation and found that GC-rich transcriptional 'strand-switch' domains composed predominantly of degenerate retrotranposons are a shared feature of regions that confer mitotic stability. Consistent with this, etoposide-mediated topoisomerase-II cleavage, a biochemical marker for active centromeres, is concentrated at these domains. In the 'megabase-sized' chromosomes of T. brucei, topoisomerase-II activity is also focused at single loci that encompass regions between directional gene clusters that contain transposable elements. Unlike T. cruzi, however, these loci also contain arrays of AT-rich repeats stretching over several kilobases. The sites of topoisomerase-II activity on T. brucei chromosome 1 and T. cruzi chromosome 3 are syntenic, suggesting that centromere location has been conserved for more than 200 million years. The T. brucei intermediate and minichromosomes, which lack housekeeping genes, do not exhibit site-specific accumulation of topoisomerase-II, suggesting that segregation of these atypical chromosomes might involve a centromere-independent mechanism.

Conclusion

The localization of centromeric DNA in trypanosomes fills a major gap in our understanding of genome organization in these important human pathogens. These data are a significant step towards identifying and functionally characterizing other determinants of centromere function and provide a framework for dissecting the mechanisms of chromosome segregation.
Dosage compensation is less effective in birds than in mammals
Authors: Itoh Yuichiro , Melamed Esther , Yang Xia , Kampf Kathy , Wang Susanna , Yehya Nadir , Van Nas Atila , Replogle Kirstin , Band Mark R , Clayton David F , Schadt Eric E , Lusis Aldons J , Arnold Arthur P
Published: March 2007

Background

In animals with heteromorphic sex chromosomes, dosage compensation of sex-chromosome genes is thought to be critical for species survival. Diverse molecular mechanisms have evolved to effectively balance the expressed dose of X-linked genes between XX and XY animals, and to balance expression of X and autosomal genes. Dosage compensation is not understood in birds, in which females (ZW) and males (ZZ) differ in the number of Z chromosomes.

Results

Using microarray analysis, we compared the male:female ratio of expression of sets of Z-linked and autosomal genes in two bird species, zebra finch and chicken, and in two mammalian species, mouse and human. Male:female ratios of expression were significantly higher for Z genes than for autosomal genes in several finch and chicken tissues. In contrast, in mouse and human the male:female ratio of expression of X-linked genes is quite similar to that of autosomal genes, indicating effective dosage compensation even in humans, in which a significant percentage of genes escape X-inactivation.

Conclusion

Birds represent an unprecedented case in which genes on one sex chromosome are expressed on average at constitutively higher levels in one sex compared with the other. Sex-chromosome dosage compensation is surprisingly ineffective in birds, suggesting that some genomes can do without effective sex-specific sex-chromosome dosage compensation mechanisms.
Monitoring Biodiesel Fuel Quality by near Infrared Spectroscopy
Authors: Felizardo Pedro , Baptista Patrícia , Uva Margarida Sousa , Menezes José C. , Correia M. Joana Neiva
Published: March 2007

Biodiesel is produced mainly by a transesterification reaction which involves the reaction of vegetable oils, animal fats or waste oils with an alcohol (such as methanol) in the presence of a catalyst (such as sodium hydroxide or methoxide). Since the presence of contaminants can cause severe engine problems, the assessment of the biodiesel quality is very important. This work reports the use of near infrared (NIR) spectroscopy to determine the content of water and methanol in industrial and laboratory-scale biodiesel samples. A qualitative analysis of the spectra by principal components analysis was carried out and partial least squares regression was used to develop calibration models between spectral and analytical data. The results indicate that the use of NIR spectroscopy, in combination with multivariate calibration, is a promising technique to assess the biodiesel quality in both laboratory-scale and industrial-scale samples.
Transflexive Embedded near Infrared Monitoring for Key Process Intermediates in Anaerobic Digestion/Biogas Production
Authors: Holm-Nielsen Jens Bo , Andree Helga , Lindorfer Harald , Esbensen Kim H.
Published: March 2007

This work reports an off-line method development simulating at-line anaerobic co-digestion process monitoring using a new transflexive embedded near infrared sensor (TENIRS) system as a process analytical chemistry (PAC) facility. The operative focus is on optimising anaerobic digestion biogas production with energy crops as the main feedstock. Results show that several key monitoring intermediates in the anaerobic fermentation process can be quantified directly using near infrared spectroscopy with good results, especially ammonium and total volatile fatty acids. Good feasibility study prediction validations have been obtained for total solids (TS), volatile solids (VS), ammonium, acetic acid and total volatile fatty acids. The TENIRS system is a new option for real-time, at-line/on-line monitoring of biogas fermentation operations, offering a robust, low-budget PAC approach to a rapidly growing bulk volume industry.