bluuebunny/crossref_metadata_2025 huggingface dataset:
Semiactive Controllers for Magnetorheological Fluid Dampers
Authors: Wang D. H. , Liao W. H.
Published: November 2005

It is challenging to control the damping forces of magnetorheological (MR) fluid dampers because of the strong nonlinearity between the damping force of an MR fluid damper and the velocity across the damper, and the semiactive relationship between the damping force and the applied voltage/current. Hence, the desired damping force ought to be generated by an MR fluid damper cannot be commanded directly, only the command voltage applied to the current driver for the MR damper can be directly controlled. In this article, the configuration of a semiactive control system with MR fluid dampers is discussed and a damper controller based on signum function for MR fluid dampers is proposed. The damper controller is used to generate and adjust the command voltage to track the desired damping force determined by the system controller based on the desired and the actual damping forces. Two key factors for controlling the damping force of an MR fluid damper through a damper controller are considered in this article: (1) tracking ability of the controlled damping force to the desired damping force, and (2) energy requirement for the MR fluid damper. The characteristics of the controlled damping force and its corresponding command voltage are analyzed and compared with the Heaviside function damper controller. The simulation results show that the signum function controller outperforms the Heaviside function controller for better damping tracking ability while requiring less energy for the MR damper.
Thrust Control Mechanism of VTOL UAV Cyclocopter with Cycloidal Blades System
Authors: Yun Chul Yong , Park Ill Kyung , Hwang In Seong , Kim Seung Jo
Published: November 2005

This study describes the control mechanism of a VTOL UAV cyclocopter. The cycloidal blades system (CBS), which is a thrust system of cyclocopter is composed of several blades rotating about a horizontal axis. To generate the required thrust, the pitch angles of the blades are periodically oscillated by a pitch control mechanism. And it can change both the magnitude and the direction of the thrust almost instantly. For the thrust control mechanism of the cyclocopter, the mathematical model is derived, and the control forces to control the magnitude and direction of the thrust are determined. In addition, it is designed and developed by radio-controlled actuators.
Simultaneous Optimal Design of Structural and Control Systems via Successive LMI Optimization
Authors: Kim J. H. , Shimomura T. , Okubo H.
Published: November 2005

This article is concerned with simultaneous optimal design of adaptive structures comprising structural and control systems. In this study, we apply the fact that the nonconvex problem is approximated by a convex one by adding a semidefinite positive function, the so-called convexifying function, to make the constraint convex. This study proposes a method of simultaneous optimization for state feedback gains and structural parameters. The system formulation is given using the descriptor form representation of the plant under the linear matrix inequality (LMI) constraint. A numerical example of a simple structure is provided to demonstrate the effectiveness of the proposed method.
Broad-band Viscoelastic Rotational Vibration Control for Remote Sensing Applications
Authors: Webster Adam L. , Semke William H.
Published: November 2005

The ability to eliminate, or effectively control, vibration in remote sensing applications is critical. Any perturbations of an imaging system are greatly magnified over the hundreds of kilometers from the orbiting space platform to the Earth's surface. Space platforms, such as the International Space Station, are not as predictable or stable as many other spacecraft. Therefore, an effective vibration isolation and/or absorber system is needed that operates over a wide range of excitation frequencies. A passive system is also preferred to reduce the resources required, as well as to provide a reliable and self-contained system. To accomplish these goals, a vibration amplitude limiting system has been developed that uses both vibration isolation and absorber components. Viscoelastic structural elements that act as both a spring and a damper in a single element are implemented in the design. This configuration also demonstrates a favorable frequencydependent response and produces a system with improved dynamic behavior compared to conventional spring and damper designs. This rotation limiting vibration system has been designed and analyzed for use in digital remote sensing imaging. The transmissibility and the ground jitter associated with the system are determined. A summary of these results will be presented along with a comparison to a more conventional vibration isolation/absorber system.
Spatial Microscopic Actuations of Shallow Conical Shell Sections
Authors: Chai W. K. , Dehaven J. G. , Tzou H. S.
Published: November 2005

In recent years there has been an interest in distributed control of shell structures because of its extensive applications in high performance structural systems. Conical shells are relevant to components of structural systems such as engine nozzles, interstage joints, satellite–rocket joints, load carrying structures for solid rocket motor cases, etc. In this paper we evaluate the spatially distributed microscopic control characteristics of distributed actuator patches laminated on conical shell surfaces. Piezoelectric materials have always been utilized for precision distributed control applications due to their converse effect. The resultant control forces and micro-control actions induced by distributed piezoelectric actuators depend on applied voltages, geometrical (e.g. spatial segmentation and shape) and material (i.e. various actuator materials) properties. Mathematical models and modal domain governing equations of the conical shell section laminated with distributed actuator patches are presented first, followed by the formulations of distributed control forces and micro-control actions, which can be refined to longitudinal and circumferential membrane/bending control components. We then evaluate the spatially distributed electromechanical microscopic actuation characteristics and control effects resulting from various longitudinal/circumferential actions of actuator patches.
Influence of Ripening Stage at Harvest on Chilling Injury Symptoms of Persimmon cv. Rojo Brillante Stored at Different Temperatures
Authors: Salvador A. , Arnal L. , Monterde A. , Martínez-Jávega J. M.
Published: November 2005

Changes in the quality during storage of persimmon fruits cv. Rojo Brillante harvested at two different maturity stages were studied. Early and late harvested fruit were stored at 1°C or 15°C for different periods of time. Harvest time had a relevant influence on chilling injury (CI) sensitiveness, since CI symptoms were found in fruits stored at 1°C only when they were early harvested. The most important CI manifestation was a drastic decrease of firmness that occurred when fruit were transferred from cold storage to 20°C. Other observed CI symptoms were internal browning, darkness of the skin, flesh structural changes, and increase of ethylene and CO2 production. Harvest date had also a considerable effect on the storage at 15°C, in this way, late harvested fruits maintained good quality for more time than early harvested ones.
Effects of the Degree of Maturity on the Chemical Composition, Physical Characteristics and Sensory Attributes of Peach (Prunus persica) cv. Caterin
Authors: Cascales A. I. , Costell E. , Romojaro F.
Published: November 2005

Sensory quality of peach during ripening to assess the best state for consumption was analysed. Physical and chemical parameters commonly used for establishing the commercial quality of this fruit were also determined: Soluble solids, acidity, sugars, organic acids, chlorophyll, carotenoids, resistance to compression and to penetration and colour. Relationships among these parameters and sensory characteristics were also analysed. A panel of eight trained assessors evaluated intensities of 12 sensory attributes (1 for odour, 2 for colour, 4 for flavour and 5 for texture). The sensory attributes selected allowed the description of perceivable differences between peaches of different degrees of maturity, although the variation in intensity of the attributes followed different trends. Colour intensity increased and acidity, firmness and crispness decreased significantly with ripening. Intensity of flavour, sweetness and fruitiness increased significantly from the under-ripe to semi-ripe states, and then decreased on reaching ripeness. It can be concluded that the most suitable time for harvesting and consumption of this peach variety was the state described herein as semi-ripe, and that a high correlation existed between colour intensity and hardness and the instrumental measurements of colour and texture.
Changes in Some Physical and Nutritional Properties of Tarhana, a Turkish Fermented Cereal Food, Added Various Phytase Sources
Authors: Bilgiçli N. , Elgün A.
Published: November 2005

The effects of three different levels of baker's yeast, barley malt flour and a microbial phytase supplement have on fermentation loss, colour, pH, total and HCl-extractable ash (HEA) and HCl-extractable phosphorus (HEP) ratio of Turkish tarhana were investigated. Fermentation loss, expressed as dry matter loss, was used for estimation of tarhana processing yield, including the fermentation, drying and grinding processes, and found on average to be 12.96%. Fermentation loss provided a proportional increase in the total ash and phosphorus content of the samples and pH decreased by adding microbial phytase. HEA and HEP content as a measurement for mineral bioavailability increased from 68.32% (dough) to 82.07% (tarhana), and from 60.45% to 83.63%, respectively, during the production process. Additions of yeast, barley malt and phytase significantly raised the HEA and HEP content ( p 0.01). Among the phytase sources, yeast was the most effective additive on the ash and phosphorus extractability. The combination of 2.5% yeast and 4% malt was the optimum treatment to obtain a low fermentation loss and high HEA and HEP. Increasing HEA and HEP values could mean higher bioavailability of minerals bound by phytic acid.
Vascular Responses to Extractable Fractions of Ilex paraguariensis in Rats Fed Standard and High-Cholesterol Diets
Authors: Stein Fabiana L. Paganini , Schmidt Bruno , Furlong Eliana Badiale , Soares Leonor A. Souza , Soares Maria Cristina Flores , Vaz Marta R. Cezar , Baisch Ana L. Muccillo
Published: November 2005

The authors investigated the vasorelaxant properties of the aqueous (Aq-EF) and acid n-butanolic (acn-BuOH) extractable fractions from Ilex paraguariensis leaves. Perfusion pressure was evaluated using isolated and perfused mesenteric arterial beds (MABs) from rats fed hypercholesterolemic and standard diets. Extract-induced vasorelaxation in the presence and absence of various inhibitors was examined following precontraction of the MABs with methoxamine (30 μM) solution. In hypercholesterolemic-diet rats, relaxation in intact MABs was significantly decreased with ac-n-BuOH-EF bolus (300, 600, 900 μg) in comparison to those in standard-diet rats. After the endothelium was stripped from the MABs, the vascular responses to ac-n-BuOH-EF and 900 μg bolus of Aq-EF were significantly changed. Treatment of the MABs with an inhibitor of nitric oxide synthase, NG -nitro-L-arginine methylester hydrochloride (L-NAME, 10 mM), did not change either ac-n-BuOH-EF- or Aq-EF-induced vasodilation except for the 900 g bolus of Aq-EF. The guanilate cyclase inhibitor methylene blue (100 μM) did not affect vasodilation for either fraction in the MABs from the hypercholesterolemic-diet rats. The chronic oral administration of I. paraguariensis extract in hypercholesterolemic-diet rats resulted in a significant reduction in serum levels of cholesterol and triglycerides. These results suggest that I. paraguariensis ac-n-BuOH-EF and Aq-EF induce vasodilation in standard-diet rats in a dose-dependent manner and that the hypercholesterolemic diet substantially reduced the effect of ac-n-BuOH-EF on precontracted MABs.
Chronic Inflammation and Breast Pathology: A Theoretical Model
Authors: Lithgow Diana , Covington Chandice
Published: November 2005

Breast cell pathology results from biochemical and molecular changes that culminate in the cell’s loss of functional responsiveness. The epithelial cell compartment in the breast ductal system is the site of approximately 98% of malignant proliferations, and it is from within these cells that the first biochemical signal of change may be expressed as an inflammatory response. Inflammation may be represented by biomarkers of early pathologic changes in breast cells and be associated with risk for the development of breast cancer. A theoretical model of the inflammatory process is proposed showing predictive linkages among stimuli in the breast microenvironment and the development of breast pathology, in particular, breast cancer. This model fuels intervention concepts that may prevent malignant breast health outcomes.
Neo-liberalizing Spaces and Subjectivities: Reinventing New Zealand Universities
Authors: Larner Wendy , Le Heron Richard
Published: November 2005

Consistent with an ongoing experience of neo-liberal experimentation, tertiary sector reform in New Zealand is being driven by the ambition to re-create universities in a qualitatively new form. We argue that, through calculative practices, New Zealand universities are being positioned and are positioning themselves in the neo-liberalizing spaces of university education. In turn, these calculative practices are giving rise to new views of the university and altering the behaviours of staff and students. We draw attention not only to the constitutive power of calculative practices, but also to the political contestations that surround them. Our conclusion is that, because of these contestations, the spaces and subjectivities of the neo-liberalizing university are multiple and contradictory. The attempted reinvention of New Zealand universities will have varied effects and give rise to multiple political forms.
The operationalization of race and ethnicity concepts in medical classification systems: issues of validity and utility
Authors: Aspinall Peter J.
Published: November 2005

This article looks at the operationalization of race and ethnicity concepts in medical classification systems, notably the main bibliographical databases of MEDLINE and EMBASE. In particular, an attempt is made to assess recent changes, including the impact of the 2004 major changes to the MeSH headings for race and ethnic groups, and the introduction of 'Continental Population Groups'. The underlying conceptual basis of the typologies, their relevance for capturing specific population groups, and their overall usefulness in appraising the literature on ethnic/racial disparities in health are examined. The bibliographical database thesauri reveal the pervasiveness of the notion of the biological basis of health differences by race/ethnicity as well as continuing use of antiquated racial terminology. Their system-oriented terminology is likely to limit the effectiveness of retrieval by users who may lack knowledge of their hierarchical structures.
Current trends in publicly available genetic databases
Authors: Tyshenko Michael G. , Leiss William
Published: November 2005

Analysis of human genetic data promises to uncover important disease targets. Genes known to cause or increase susceptibility for various diseases are being identified through analysis of genetic data, expression and metabolites. Future benefits to individuals are far-reaching, including improved gene therapy strategies, better drug development for disease treatment, pre-symptomatic disease intervention and risk susceptibility information. The rapid expansion of genetic databases has resulted in the emerging areas of genomics, transcriptomics, proteomics and metabolomics. The article presents a comprehensive overview of Internet databases, their trends over time and what 'omics' type they embody. With the completion of the human genome we are entering the postgenomic era. The use of microarrays and database software for genomic, transcriptomic, proteomic and metabolomic data for clinical assays and new diagnostic therapeutics will result in large, interlinked databases that will present unique issues of data management, standardization and information sharing.
Measuring psychological well-being in cognitively impaired persons
Authors: Burgener Sandy C. , Twigg Prudence , Popovich Ann
Published: November 2005

An objective measure of psychological well-being (a previously understudied outcome for persons with dementia) was developed and tested as part of a longitudinal study ( n= 96 participant pairs; n= 73 pairs remaining at 18 months). The reliability and validity of the Psychological Well-being in Cognitively Impaired Persons (PWB-CIP) scale was examined as a measure of one dimension of quality of life (QoL) as persons progress in the disease. The original 16-item PWB-CIP Likert-type scale required only five to 10 minutes to complete and was reduced to 11 items following factor analysis. Cronbach's alpha for the total scale was .79 at baseline and .82 at 18 months. Two subscales were identified: positive affect/interaction and negative affect/interaction. One item ('involved in a single activity for > five minutes') loaded on a different subscale at baseline (early disease stages) compared to 18 months (reflecting disease progression). The internal consistency of the two subscales remained acceptable across the two measurement intervals. Controlling for mental status, the PWB-CIP's construct validity was supported through significant relationships with depression, personal characteristics (personality), and the behavioral competence QoL dimensions at baseline and at 18 months. Because both rural (55%) and urban populations were sampled and the PWB-CIP was used across care settings, the findings support the PWB-CIP as a psychometrically sound measure of psychological well-being for diverse populations of persons with dementia.
Alzheimer's dementia in persons with Down's syndrome
Authors: McCarron Mary , Gill Michael , Mccallion Philip , Begley Cecily
Published: November 2005

The aim of this study was to investigate the amount of time formal caregivers spend addressing activities of day-to-day care activities for persons with Down's syndrome (DS) with and without Alzheimer's dementia (AD). Caregivers completed for 63 persons with DS and AD, and 61 persons with DS without AD, the Caregiving Activity Survey-Intellectual Disability (CAS-ID). Data was also gathered on co-morbid conditions. Regression analysis was used to understand predictors of increased time spent on day-to-day caregiving. Significant differences were found in average time spent in day-to-day caregiving for persons with and without AD. Mid-stage and end-stage AD, and co-morbid conditions were all found to predict increased time spent caregiving. Nature and tasks of day-to-day caregiving appeared to change as AD progressed. The study concluded that staff time to address day-to-day caregiving needs appeared to increase with onset of AD and did so most dramatically for persons with moderate intellectual disability. Equally, while the tasks for staff were different, time demands in caring for persons at both mid-and end-stage AD appeared similar.
Embodied selfhood in Alzheimer's disease
Authors: Kontos Pia C.
Published: November 2005

Dementia care practices are premised on a model of Alzheimer's disease that denies the body an agential role in the constitution and manifestation of selfhood. As a consequence, despite advances in person-centred care, the body, which is a substantive means by which persons with advancing dementia engage with the world, is treated as passive rather than active and intentional. My central argument is that dementia care practices must embrace the idea that the body is a fundamental source of selfhood that does not derive its agency from a cognitive form of knowledge. With an interest in bringing the body into a theoretical re-visioning of selfhood in Alzheimer's disease, I advance this idea with the notion of embodied selfhood. I suggest ways that the notion of embodied selfhood could enhance person-centred dementia care; however, further research is required in order to fully conceptualize this notion in the context of dementia care.
Creativity as a Drive for Change
Authors: Albrechts Louis
Published: November 2005

This article argues that society as a whole and planning in particular need more creative responses to the problems and challenges they face. Planning needs creativity to imagine and to construct (structurally) different futures. First, the article briefly analyses two case studies: the Hasselt case as an example of creative transport planning and creative local governance; and the Perth case as an example of distorted creativity. Then the article questions the nature of planning creativity needs and looks for a systematic method. Scenario building turns out to be an excellent tool for conceiving possible futures and their processes, what must be changed first and what next. Just as there are many traditions and collective practices there are also many images of what a society wants to achieve. As the opportunities for implementing images are not equal the article reflects on a planning annex governance system that serves all citizens and especially the least powerful. All this has an impact on planners as well. In the final part, the article touches briefly on some preconditions for creativity, on how it could be enhanced and on how realistic the discourse itself is.
Straddling the Post-Structuralist Abyss: Between Transcendence and Immanence?
Authors: Hillier Jean
Published: November 2005

Against a background of socio-economic change, planning practitioners are struggling to embrace the various processes of transformation of structures and practices in meaningful ways. Theorists, in turn, are struggling to come to terms with these practice transformations. Whilst many theorists would accept the need for dynamic, relational approaches there is strong debate about the meanings and implications of new theory. Tensions may arise from fundamental differences between transcendental and immanent frames: practice and theory seek immanence, yet are caught in remnants of transcendence. I explore the potential of Deleuze and Guattari's concept of 'becoming' as creative experimentation. I conclude that planning may involve a transcendental structure immanent in its practical local expressions; and that theorizing could benefit from ' becomingplanning'.
Resurrection Research From 1975 to the Present: What are Critical Scholars Saying?
Authors: Habermas Gary
Published: November 2005

An overview of resurrection research in Europe and North America during the last 30 years indicates some expected as well as some surprising trends. This study highlights six of these major research areas. The works of two representative scholars, J.D. Crossan and N.T. Wright, provide interpretive angles on these subjects. The article concludes with some comments on what is taken to be the single most crucial development at present, that after Jesus' death his followers had experiences that they thought were appearances of the risen Jesus. These early Christian experiences need to be explained viably.
Explaining the Resurrection: Conflicting Convictions
Authors: Allison Dale
Published: November 2005

Although explanations for the earliest Christian proclamation of Jesus' resurrection vary, certain standard arguments appear again and again. The present article introduces those explanations and those arguments as well as the essays in this theme issue of JSHJ, with a view to clarifying what they add to the traditional discussion.
Inhaled tolafentrine reverses pulmonary vascular remodeling via inhibition of smooth muscle cell migration
Authors: Pullamsetti Soni , Krick Stefanie , Yilmaz Hüseyin , Ghofrani Ardeschir Hossein , Schudt Christian , Weissmann Norbert , Fuchs Beate , Seeger Werner , Grimminger Friedrich , Schermuly Ralph Theo
Published: November 2005

Background

The aim of the study was to assess the chronic effects of combined phosphodiesterase 3/4 inhibitor tolafentrine, administered by inhalation, during monocrotaline-induced pulmonary arterial hypertension (PAH) in rats.

Methods

CD rats were given a single subcutaneous injection of monocrotaline to induce PAH. Four weeks after, rats were subjected to inhalation of tolafentrine or sham nebulization in an unrestrained, whole body aerosol exposure system. In these animals (i) the acute pulmonary vasodilatory efficacy of inhaled tolafentrine (ii) the anti-remodeling effect of long-term inhalation of tolafentrine (iii) the effects of tolafentrine on the expression profile of 96 genes encoding cell adhesion and extracellular matrix regulation were examined. In addition, the inhibitory effect of tolafentrine on ex vivo isolated pulmonary artery SMC cell migration was also investigated.

Results

Monocrotaline injection provoked severe PAH (right ventricular systolic pressure increased from 25.9 ± 4.0 to 68.9 ± 3.2 after 4 weeks and 74.9 ± 5.1 mmHg after 6 weeks), cardiac output depression and right heart hypertrophy. The media thickness of the pulmonary arteries and the proportion of muscularization of small precapillary resistance vessels increased dramatically, and the migratory response of ex-vivo isolated pulmonary artery smooth muscle cells (PASMC) was increased. Micro-arrays and subsequent confirmation with real time PCR demonstrated upregulation of several extracellular matrix regulation and adhesion genes, such as matrixmetalloproteases (MMP) 2, 8, 9, 10, 11, 12, 20, Icam, Itgax, Plat and serpinb2. When chronically nebulized from day 28 to 42 (12 daily aerosol maneuvers), after full establishment of severe pulmonary hypertension, tolafentrine reversed about 60% of all hemodynamic abnormalities, right heart hypertrophy and monocrotaline-induced structural lung vascular changes, including the proportion of pulmonary artery muscularization. The upregulation of extracellular matrix regulation and adhesion genes was reduced by nearly 80% by inhalation of the tolafentrine. When assessed in vitro, tolafentrine blocked the enhanced PASMC migratory response.

Conclusion

In conclusion, we demonstrate for the first time that inhalation of combined PDE3/4 inhibitor reverses pulmonary hypertension fully developed in response to monocrotaline in rats. This "reverse-remodeling" effect includes structural changes in the lung vascular wall and key molecular pathways of matrix regulation, concomitant with 60% normalization of hemodynamics.
The crucial role of particle surface reactivity in respirable quartz-induced reactive oxygen/nitrogen species formation and APE/Ref-1 induction in rat lung
Authors: Albrecht Catrin , Knaapen Ad M , Becker Andrea , Höhr Doris , Haberzettl Petra , van Schooten Frederik J , Borm Paul JA , Schins Roel PF
Published: November 2005

Persistent inflammation and associated excessive oxidative stress have been crucially implicated in quartz-induced pulmonary diseases, including fibrosis and cancer. We have investigated the significance of the particle surface reactivity of respirable quartz dust in relation to the in vivo generation of reactive oxygen and nitrogen species (ROS/RNS) and the associated induction of oxidative stress responses in the lung. Therefore, rats were intratracheally instilled with 2 mg quartz (DQ12) or quartz whose surface was modified by either polyvinylpyridine-N-oxide (PVNO) or aluminium lactate (AL). Seven days after instillation, the bronchoalveolar lavage fluid (BALF) was analysed for markers of inflammation (total/differential cell counts), levels of pulmonary oxidants (H2O2, nitrite), antioxidant status (trolox equivalent antioxidant capacity), as well as for markers of lung tissue damage, e.g. total protein, lactate dehydrogenase and alkaline phosphatase. Lung homogenates as well as sections were investigated regarding the induction of the oxidative DNA-lesion/oxidative stress marker 8-hydroxy-2'-deoxyguanosine (8-OHdG) using HPLC/ECD analysis and immunohistochemistry, respectively. Homogenates and sections were also investigated for the expression of the bifunctional apurinic/apyrimidinic endonuclease/redox factor-1 (APE/Ref-1) by Western blotting and immunohistochemistry. Significantly increased levels of H2O2 and nitrite were observed in rats treated with non-coated quartz, when compared to rats that were treated with either saline or the surface-modified quartz preparations. In the BALF, there was a strong correlation between the number of macrophages and ROS, as well as total cells and RNS. Although enhanced oxidant generation in non-coated DQ12-treated rats was paralleled with an increased total antioxidant capacity in the BALF, these animals also showed significantly enhanced lung tissue damage. Remarkably however, elevated ROS levels were not associated with an increase in 8-OHdG, whereas the lung tissue expression of APE/Ref-1 protein was clearly up-regulated. The present data provide further in vivo evidence for the crucial role of particle surface properties in quartz dust-induced ROS/RNS generation by recruited inflammatory phagocytes. Our results also demonstrate that quartz dust can fail to show steady-state enhanced oxidative DNA damage in the respiratory tract, in conditions were it elicits a marked and persistent inflammation with associated generation of ROS/RNS, and indicate that this may relate to compensatory induction of APE/Ref-1 mediated base excision repair.
Selecting additional tag SNPs for tolerating missing data in genotyping
Authors: Huang Yao-Ting , Zhang Kui , Chen Ting , Chao Kun-Mao
Published: November 2005

Background

Recent studies have shown that the patterns of linkage disequilibrium observed in human populations have a block-like structure, and a small subset of SNPs (called tag SNPs) is sufficient to distinguish each pair of haplotype patterns in the block. In reality, some tag SNPs may be missing, and we may fail to distinguish two distinct haplotypes due to the ambiguity caused by missing data.

Results

We show there exists a subset of SNPs (referred to as robust tag SNPs) which can still distinguish all distinct haplotypes even when some SNPs are missing. The problem of finding minimum robust tag SNPs is shown to be NP-hard. To find robust tag SNPs efficiently, we propose two greedy algorithms and one linear programming relaxation algorithm. The experimental results indicate that (1) the solutions found by these algorithms are quite close to the optimal solution; (2) the genotyping cost saved by using tag SNPs can be as high as 80%; and (3) genotyping additional tag SNPs for tolerating missing data is still cost-effective.

Conclusion

Genotyping robust tag SNPs is more practical than just genotyping the minimum tag SNPs if we can not avoid the occurrence of missing data. Our theoretical analysis and experimental results show that the performance of our algorithms is not only efficient but the solution found is also close to the optimal solution.
The neuroblast and angioblast chemotaxic factor SDF-1 (CXCL12) expression is briefly up regulated by reactive astrocytes in brain following neonatal hypoxic-ischemic injury
Authors: Miller Jason T , Bartley John H , Wimborne Hereward JC , Walker Aisha L , Hess David C , Hill William D , Carroll James E
Published: November 2005

Background

Stromal cell-derived factor 1 (SDF-1 or CXCL12) is chemotaxic for CXCR4 expressing bone marrow-derived cells. It functions in brain embryonic development and in response to ischemic injury in helping guide neuroblast migration and vasculogenesis. In experimental adult stroke models SDF-1 is expressed perivascularly in the injured region up to 30 days after the injury, suggesting it could be a therapeutic target for tissue repair strategies. We hypothesized that SDF-1 would be expressed in similar temporal and spatial patterns following hypoxic-ischemic (HI) injury in neonatal brain.

Results

Twenty-five 7-day-old C57BL/J mice underwent HI injury. SDF-1 expression was up regulated up to 7 days after the injury but not at the later time points. The chief sites of SDF-1 up regulation were astrocytes, their foot processes along blood vessels and endothelial cells.

Conclusion

The localization of SDF-1 along blood vessels in the HI injury zone suggests that these perivascular areas are where chemotaxic signaling for cellular recruitment originates and that reactive astrocytes are major mediators of this process. The associated endothelium is likely to be the site for vascular attachment and diapedesis of CXCR4 receptor expressing cells to enter the injured tissue. Here we show that, relative to adults, neonates have a significantly smaller window of opportunity for SDF-1 based vascular chemotaxic recruitment of bone marrow-derived cells. Therefore, without modification, following neonatal HI injury there is only a narrow period of time for endogenous SDF-1 mediated chemotaxis and recruitment of reparative cells, including exogenously administered stem/progenitor cells.
Parametric versus non-parametric statistics in the analysis of randomized trials with non-normally distributed data
Authors: Vickers Andrew J
Published: November 2005

Background

It has generally been argued that parametric statistics should not be applied to data with non-normal distributions. Empirical research has demonstrated that Mann-Whitney generally has greater power than thet-test unless data are sampled from the normal. In the case of randomized trials, we are typically interested in how an endpoint, such as blood pressure or pain, changes following treatment. Such trials should be analyzed using ANCOVA, rather thant-test. The objectives of this study were: a) to compare the relative power of Mann-Whitney and ANCOVA; b) to determine whether ANCOVA provides an unbiased estimate for the difference between groups; c) to investigate the distribution of change scores between repeat assessments of a non-normally distributed variable.

Methods

Polynomials were developed to simulate five archetypal non-normal distributions for baseline and post-treatment scores in a randomized trial. Simulation studies compared the power of Mann-Whitney and ANCOVA for analyzing each distribution, varying sample size, correlation and type of treatment effect (ratio or shift).

Results

Change between skewed baseline and post-treatment data tended towards a normal distribution. ANCOVA was generally superior to Mann-Whitney in most situations, especially where log-transformed data were entered into the model. The estimate of the treatment effect from ANCOVA was not importantly biased.

Conclusion

ANCOVA is the preferred method of analyzing randomized trials with baseline and post-treatment measures. In certain extreme cases, ANCOVA is less powerful than Mann-Whitney. Notably, in these cases, the estimate of treatment effect provided by ANCOVA is of questionable interpretability.
High carriage rate of high-level penicillin-resistant Streptococcus pneumoniaein a Taiwan kindergarten associated with a case of pneumococcal meningitis
Authors: Lauderdale Tsai-Ling , Lee Wei Yang , Cheng Ming Fang , Huang I Fei , Lin Yu Chen , Hseih Kai Sheng , Huang I-Wen , Chiou Christine C
Published: November 2005

Background

The Taiwan19F-14 Streptococcus pneumoniae clone and its variants are being found with increasing frequency in the Asia-Pacific region. A 5-year old child with S. pneumoniae meningitis caused by a high-level penicillin resistant strain (MIC = 4 μg/ml) was admitted to a hospital in southern Taiwan. We carried out a study to determine the potential source of this strain.

Methods

Nasopharyngeal cultures were obtained from all children attending the same kindergarten as the index case. To determine their relatedness all isolates were compared by serotype, antimicrobial susceptibility profile and pulsed field gel electrophoresis (PFGE).

Results

A high proportion of the children including the index case (32/78, 41.0%) carried S. pneumoniae in their nasopharynx (NP). The most common serotype was 19F (13/32, 40.6%). The PFGE types of the 19F serotype isolates obtained from the patient's blood, CSF and NP were identical and were related to 11 other serotype 19F NP isolates including 10 that were indistinguishable from the Taiwan19F-14 clone. All 14 isolates had similar high-level penicillin and multi-drug resistance. The serotypes of the other 19 NP isolates included 6A (2), 6B (10), 23F (5), 9V (1) and 3 (1). The overall rate of penicillin resistance in these S. pneumoniae from these children was 87.5% (28/32), with an MIC50 of 2 and MIC90 of 4 ug/ml. In addition, multi-drug resistant-isolates (isolates resistant to 3 different classes of antimicrobials) accounted for 87.5% (28/32) of all isolates.

Conclusion

The high carriage rate of high-level penicillin- and multi-drug- resistant S. pneumoniae in a kindergarten associated with a case of pneumococcal meningitis emphasizes the need for restraint in antibiotic use and consideration of childhood immunization with conjugate pneumococcal vaccine to prevent the further spread of resistant S. pneumoniae in Taiwan.
A functional profile of gene expression in ARPE-19 cells
Authors: Sharma Rajesh K , Orr William E , Schmitt Allyson D , Johnson Dianna A
Published: November 2005

Background

Retinal pigment epithelium cells play an important role in the pathogenesis of age related macular degeneration. Their morphological, molecular and functional phenotype changes in response to various stresses. Functional profiling of genes can provide useful information about the physiological state of cells and how this state changes in response to disease or treatment. In this study, we have constructed a functional profile of the genes expressed by the ARPE-19 cell line of retinal pigment epithelium.

Methods

Using Affymetrix MAS 5.0 microarray analysis, genes expressed by ARPE-19 cells were identified. Using GeneChip® annotations, these genes were classified according to their known functions to generate a functional gene expression profile.

Results

We have determined that of approximately 19,044 unique gene sequences represented on the HG-U133A GeneChip® , 6,438 were expressed in ARPE-19 cells irrespective of the substrate on which they were grown (plastic, fibronectin, collagen, or Matrigel). Rather than focus our subsequent analysis on the identity or level of expression of each individual gene in this large data set, we examined the number of genes expressed within 130 functional categories. These categories were selected from a library of HG-U133A GeneChip® annotations linked to the Affymetrix MAS 5.0 data sets. Using this functional classification scheme, we were able to categorize about 70% of the expressed genes and condense the original data set of over 6,000 data points into a format with 130 data points. The resulting ARPE-19 Functional Gene Expression Profile is displayed as a percentage of ARPE-19-expressed genes.

Conclusion

The Profile can readily be compared with equivalent microarray data from other appropriate samples in order to highlight cell-specific attributes or treatment-induced changes in gene expression. The usefulness of these analyses is based on the assumption that the numbers of genes expressed within a functional category provide an indicator of the overall level of activity within that particular functional pathway.
Indications and outcome of repeat penetrating keratoplasty in India
Authors: Vanathi M , Sharma Namrata , Sinha Rajesh , Tandon Radhika , Titiyal Jeewan S , Vajpayee Rasik B
Published: November 2005

Background

Repeat penetrating keratoplasty is quite often required as there is high chance of failure of the primary graft particularly in the developing world. We planned a study to analyze the indications and outcome of repeat penetrating keratoplasty in a tertiary care centre in India.

Methods

A retrospective analysis of all the patients who underwent repeat penetrating keratoplasty, between January 1999 and December 2001 was performed. The parameters evaluated were indication for the primary penetrating keratoplasty, causes of failure of the previous graft, and final visual outcome and clarity of the repeat corneal grafts.

Results

Of fifty-three eyes of 50 patients with repeat penetrating keratoplasty (three patients underwent bilateral corneal regrafts), 37 eyes had undergone one regraft each, 14 eyes two regrafts and two eyes had three regrafts. The follow-up of the patients ranged from one to three years. The most common primary etiologic diagnosis was vascularized corneal scars (66%), of which the scars related to infection were most common (68.5%). Twenty-eight regrafts (52.8%) remained clear at a mean follow-up of 1.54 ± 0.68 years, of which 25 were single regrafts (89.3%). The commonest cause of failure of regraft was infection to the corneal graft (recurrence of herpetic infection in 9 eyes and perforated graft ulcers in 3 eyes). Three (18.6%) of the 16 eyes with multiple corneal regrafts achieved a BCVA of 6/60. Overall, only five eyes (all with single regraft) achieved a BCVA of 6/18 or better at the end of follow-up.

Conclusion

Graft infection is the leading cause of failure of repeat keratoplasty in this part of the world. Prognosis for visual recovery and graft survival is worse in eyes undergoing multiple regrafts.
Testing assumptions for endophenotype studies in ADHD: Reliability and validity of tasks in a general population sample
Authors: Kuntsi Jonna , Andreou Penny , Ma Jonathan , Börger Norbert A , van der Meere Jaap J
Published: November 2005

Background

Advances in both genetic and cognitive-experimental studies on attention deficit hyperactivity disorder (ADHD) have opened new opportunities for cognitive endophenotype research. In such genetic designs the focus is on individual differences in characteristics, associated with ADHD, that can be measured reliably over time. Genetic studies that take a 'quantitative trait loci' approach hypothesise that multiple susceptibility genes contribute to a continuous dimension of ADHD symptoms. As an important initial step, we aimed to investigate the underlying assumptions that (1) key cognitive-experimental tasks indicate adequate test-retest reliability and (2) ADHD symptom scores in a general population sample are associated with performance on these tasks.

Methods

Forty-nine children were assessed on a go/no-go task and a reaction time task (the 'fast task') that included manipulations with event rate and incentives. The children were assessed twice, with a test-retest interval of two weeks.

Results

The majority of the task variables demonstrated moderate-to-good test-retest reliability. The correlations between teacher ratings of ADHD symptoms and key task variables were .4–.6: ADHD symptoms were associated with poor performance (especially high reaction time variability) in a slow baseline condition, whereas there was low or no association in conditions with a faster event rate or incentives. In contrast, no clear pattern of findings emerged based on parent ratings of ADHD symptoms.

Conclusion

The data support the usefulness of the go/no-go and fast tasks for genetic studies, which require reliable and valid indices of individual differences. The overall pattern of associations between teacher ratings of ADHD symptoms and task variables is consistent with effects of event rate and incentives on performance, as predicted by the model of activation and arousal regulation. The lack of a clear pattern of findings with parent ratings of ADHD symptoms warrants further study.
Blood pressure patterns in rural, semi-urban and urban children in the Ashanti region of Ghana, West Africa
Authors: Agyemang Charles , Redekop William K , Owusu-Dabo Ellis , Bruijnzeels Marc A
Published: November 2005

Background

High blood pressure, once rare, is rapidly becoming a major public health burden in sub-Saharan/Africa. It is unclear whether this is reflected in children. The main purpose of this study was to assess blood pressure patterns among rural, semi-urban, and urban children and to determine the association of blood pressure with locality and body mass index (BMI) in this sub-Saharan Africa setting.

Methods

We conducted a cross-sectional survey among school children aged 8–16 years in the Ashanti region of Ghana (West-Africa). There were 1277 children in the study (616 boys and 661 females). Of these 214 were from rural, 296 from semi-urban and 767 from urban settings.

Results

Blood pressure increased with increasing age in rural, semi-urban and urban areas, and in both boys and girls. The rural boys had a lower systolic and diastolic blood pressure than semi-urban boys (104.7/62.3 vs. 109.2/66.5; p < 0.001) and lower systolic blood pressure than urban boys (104.7 vs. 107.6; p < 0.01). Girls had a higher blood pressure than boys (109.1/66.7 vs. 107.5/63.8; p < 0.01). With the exception of a lower diastolic blood pressure amongst rural girls, no differences were found between rural girls (107.4/64.4) and semi-urban girls (108.0/66.1) and urban girls (109.8/67.5). In multiple linear regression analysis, locality and BMI were independently associated with blood pressure in both boys and girls.

Conclusion

These findings underscore the urgent need for public health measures to prevent increasing blood pressure and its sequelae from becoming another public health burden. More work on blood pressure in children in sub-Saharan African and other developing countries is needed to prevent high blood pressure from becoming a major burden in many of these countries.
The use and diagnostic yield of radiology in subjects with longstanding musculoskeletal pain – an eight year follow up
Authors: Lindgren Hans , Bergman Stefan
Published: November 2005

Background

Longstanding musculoskeletal pain is common in the general population and associated with frequent use of health care. Plain radiography is a common diagnostic approach in these patients despite knowledge that the use in the investigation of musculoskeletal pain is associated with low diagnostic yield, substantial costs and high radiation exposure. The aim of this study was to assess the use of diagnostic imaging and the proportion of pathological findings with regard to duration and distribution of pain in a cohort from the general population.

Methods

An eight-year longitudinal study based on questionnaires at three occasions and medical records on radiological examinations done in medical care. Thirty subjects were selected from an established population based cohort of 2425 subjects that in 1995 answered a postal survey on pain experience. At baseline there were ten subjects from each of three pain groups; No chronic pain, Chronic regional pain, and Chronic widespread pain (CWP). Those who presented with CWP at two or all three occasions were considered to have a longstanding or re-occurring CWP. In total the thirty subjects underwent 102 radiological examinations during the eight year follow up.

Results

There was a non-significant (p = 0.10) finding indicating that subjects with chronic pain at baseline (regional or widespread) were examined three times more often than those with no chronic pain. When the indication for the examination was pain, there was a low proportion of positive findings in subjects with longstanding CWP, compared to all others (5.3% vs 28.9%; p = 0.045). On the other hand, in examinations on other indications than pain the proportion of positive findings was high in the CWP group (62.5% vs 14.8%; p = 0.001).

Conclusion

Radiological examinations had a low diagnostic yield in evaluation of pain in subjects with longstanding/reoccurring CWP. These subjects had on the other hand more often positive findings when examined on other indications than pain. This may indicate that subjects with longstanding/reoccurring CWP are more prone to other diseases. It is a challenge for caregivers, often primary care physicians, to use radiological examinations to the best for their patients.