bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Investigation of Injection Molding of Wood/Plastics Composites
Authors: Behravesh A.H. , Zohdi Aghdam A. , Soury E.
Published: January 2009

In this article, injection processing of wood flour/PP composite and the effects of processing parameters on its mechanical properties are investigated. Injection pressure and pressure holding time were systematically chosen as the critical processing parameters. The results of this research work indicate that increasing injection pressure and holding time has considerable effect on final modulus of elasticity, noticeable decreasing effect on elongation, and insignificant effect on tensile strength.
Investigation of Fracture Toughness of Laminated Stitched Composites Subjected to Mixed Mode Loading
Authors: Rys Tomek , Sankar Bhavani V. , Ifju Peter G.
Published: January 2009

Through-the-thickness stitching is a method that increases the translaminar strength and apparent fracture toughness of laminated composites. A novel test fixture was developed to measure mixed mode fracture toughness under combined Mode I and Mode II loadings. This fixture allowed the ratio between Mode I and Mode II to be varied in order to perform tests under a wide range of mixed mode conditions. Through testing it has been shown that stitching increases Mode I fracture toughness 20—50 times while playing a less significant role in increasing Mode II fracture toughness.
RETRACTED: Friction and Wear Properties of PA6-reinforced PTFE Composites
Authors: Li J.
Published: January 2009

Retracted
The Influence of Interface Geometry on the Joint Strengths of Hot Plate Welded Composites
Authors: Liu Shih-Jung , Cheng Hsin-Fu
Published: January 2009

Interface geometry before joining has been an important factor for the welding quality of hot plate welding. In the present study, weld interfaces of six different geometries were studied, namely flat, triangular (30°, 45°, and 60°), rectangular, and semi-circular interfaces. Three materials were used in the study: virgin polypropylene, and 20 and 30% glass fiber-reinforced polypropylene composites. All specimens used in the experiments were molded using a pin injection gate on a reciprocating injection molding machine. After welding, the joint strength of the composites was determined by a tensile tester. Welded 20% glass fiber-reinforced polymers were found to exhibit the highest joint strengths. For the parameters selected in the experiments, hot plate temperature, heating time, and geometry of weld interface were found to be the principal factors affecting the joint property of hot plate welded composites. In addition, the triangular and rectangular weld interfaces were found to weld parts of the highest strengths for virgin polypropylene and 20% glass fiber-reinforced polypropylene composites, respectively, while the joint strengths of 30% fiber-reinforced composites were improved by adopting non-flat weld interface geometries.
As2O3 toxicity in rat hepatocytes: manifestation of caspase-mediated apoptosis
Authors: Ray A , Roy S , Agarwal S , Bhattacharya S
Published: January 2009

In India, arsenic contamination in ground water is of immediate environmental concern affecting a large number of inhabitants in Kolkata. Arsenic is known to be one of the most toxic metalloids naturally occurring in the environment giving rise to severe toxic manifestations including cancer. Because arsenic is also used in chemotherapy of leukemia, it was considered worthwhile to concentrate on the mechanism of toxic action in normal hepatocytes which has not been addressed earlier. Rat hepatocytes were isolated and incubated in As2O3 at concentrations of 10, 20, and 40 μM in a time-dependent manner (0, 15, 30 min and 1, 2, and 4 h). The expression of the common stress proteins HSP 70 and 90 throughout the experimental duration confirmed the magnitude of toxic effect imposed by arsenic. Microscopic observations showed clear apoptotic changes in hepatocytes, which were further characterized by DNA ladder formation in time- and concentration-dependent manners. Apoptosis was triggered by caspase activation and over expression of bax at 10 μM As2O3 and at 20 and 40 μM concentrations of As2O3, MAP kinases were found to mediate the apoptotic pathway. Co-treatment of cells with arsenic and caspase inhibitor (Ac-DEVD-Cho) led to over expression of bcl-2, suppression of bax, and cytosolic sequestration of Bid and Bad. It is therefore concluded that caspase activation has a direct role in arsenic-induced apoptosis mediated by mitochondrial factors at 10 μM As2O3, and JUN N-terminal kinase (JNK) and P38 activation are the major mediators of apoptosis at the higher test concentrations (20 and 40 μM) of As2O3.
Strain-type Sensor Networks for Structural Monitoring of Beam-type Structures
Authors: Krommer M. , Zellhofer M. , Heilbrunner K.-H.
Published: January 2009

In our previous work, we have shown that distributed strain-type sensors can be used to measure desired structural entities. A distributed strain-type sensor, whose distribution coincides with any statically admissible stress distribution due to quasi-static auxiliary forces, measures the work of these forces done on the original structural entities. Hence, a proper choice of the auxiliary forces results in the measurement of desired structural entities. In this article, we focus on the approximation of distributed sensors by sensor networks composed of sensor patches with constant intensity. The question is where to locate and how to assign weights to the patches such that the combined output of the network approximates the output of the distributed sensor. Our method is based on an integral statement characterizing the output of the distributed sensor and an integral statement for the output of the sensor network. As we cannot ensure the identity of the kernels of the integral statements, we develop methods ensuring the identity of the integral statements themselves. We develop the method for beam-type structures in detail. As a case study, we discuss a one-story frame structure and we seek to design sensor networks to measure desired structural entities; e.g., deflections or slopes.
Structural Effects and Energy Conversion Efficiency of Power Harvesting
Authors: Yabin Liao  , Sodano Henry A.
Published: January 2009

The concept of power harvesting works towards developing self-powered devices that do not require replaceable power supplies. One important parameter defining the performance of a piezoelectric power harvesting system is the efficiency of the system. However, an accepted definition of energy harvesting efficiency does not currently exist. This article will develop a new definition for the efficiency of an energy harvesting system, which rather than being defined through energy conservation as the ratio of the energy fed into the system to maintain the steady state to the output power, we consider the ratio of the strain energy over each cycle to the power output. This new definition is analogous to the material loss factor. Simulations will be performed to demonstrate the validity of the efficiency and will show that the maximum efficiency occurs at the matched impedance; however, for materials with high electromechanical coupling, the maximum power is generated at the near open- and closed-circuit resonances with a lower efficiency.
Gaussian Process Time Series Model for Life Prognosis of Metallic Structures
Authors: Mohanty Subhasish , Das Santanu , Chattopadhyay Aditi , Peralta Pedro
Published: January 2009

Al 2024-T351 fatigue specimens have been modeled using a kernel-based multi-variate Gaussian Process approach. The Gaussian Process model projects fatigue affecting input variables to output crack growth by probabilistically inferring the underlying nonlinear relationship between input and output. The Gaussian Process approach not only explicitly models the uncertainty due to scatter in material microstructure parameter but it also implicitly models the loading sequence effect due to variable loading. The loading sequence effect is modeled through the Gaussian Process optimal hyperparameters by using the crack length data observed over the entire domain of spectrum loading. The performance in the crack growth prediction is evaluated for two covariance functions, a radial basis-based, anisotropic, covariance function and a neural network-based isotropic covariance function. Furthermore, the performance of different types of scaling, used to scale the input—output data space, is tested. It is found that for the radial basis-based anisotropic covariance function with normalized scaling, the prediction error is consistently lower compared to other combinations. In addition, the Gaussian Process model allows determination of the collapse load condition, which is a desirable feature for the online health monitoring and prognosis.
In-plane Tensile Behavior of Shape Memory Alloy Honeycombs with Positive and Negative Poisson's Ratio
Authors: Hassan M.R. , Scarpa F. , Mohamed N.A.
Published: January 2009

This work illustrates the manufacturing and tensile testing of a novel concept of honeycomb structures with hexagonal and auxetic (negative Poisson's ratio) topology, made of shape memory alloy core material. The honeycombs are manufactured using Nitinol ribbons having 6.40 mm of width and 0.2 mm of thickness. The ribbons were inserted in a special dye using cyanoacrilate to bond the longitudinal strips of the unit cells. Tensile tests at room temperature (full martensite) were performed on the honeycombs. Finite element models of the honeycomb assemblies under tensile loading have been developed using nonlinear beam elements from a commercial code. Good agreement is observed between numerical nonlinear simulations and the experimental results.
Modeling and Control of a Membrane Strip Using a Single Piezoelectric Bimorph
Authors: Renno Jamil M. , Inman Daniel J.
Published: January 2009

This paper presents an improved finite-element model of a membrane strip actuated by a single piezoelectric bimorph. The paper also treats the static shape control problem of the structure under study. The membrane strip is modeled as an Euler—Bernoulli beam under tension, with non-uniform physical properties. The finite-element method allows the development of a model that accounts for the actuator dynamics. The static shape control problem is formulated as a disturbance rejection problem and solved using a proportional-integral (PI) controller. The PI control gains are obtained using the linear quadratic regulator theory. The proposed model is verified experimentally, and the closed loop system is simulated to demonstrate the effectiveness of the control law.
Optimal Active Control of a Deformable Mirror
Authors: Chellabi Abdelkader , Stepanenko Yury , Dost Sadik
Published: January 2009

A new control design method for active shape control of a dynamic flexible structures with piezoelectric inclusions is developed. It is applied mainly for applications such as deformable mirrors of an adaptive optics system, space-based imaging systems and other applications where deformable mirrors constitute part of the system. In this method, the dynamics of the flexible structure — the mirror — is included in the controller design in the form of algebraic equations of motion. The algebraic optimal control laws are derived in an explicit form for a general time-varying distributed parameter system with piezoelectric inclusions. The essence of the approach is based on using space-time assumed mode expansions of the generalized coordinates and inputs, or in other words the Rayleigh—Ritz method extended to both space and time dimensions in conjunction with variational work—energy principles that govern the physical system. An optimal tracking controller was designed for shaping the surface of the deformable mirror used in an adaptive optics system. The desired time-changing surface trajectory can be supplied analytically or by point data that can be curve fitted using Zernike polynomials for wavefront distortions for direct use. One feature of this method is that it accommodates the dynamic behavior of the structure instead of considering only the static shape control. It is shown through illustrated examples that the controller can operate at much higher control frequencies than what is currently reported in the literature.
Design of Delayed Reference Controllers for Simultaneous Path Tracking and Active Vibration Damping of Multi-degree-of-freedom Linear Systems
Authors: Richiedei D. , Trevisani A.
Published: January 2009

This paper presents an innovative non-time-based control strategy for the simultaneous path tracking and active vibration damping of multi-degree-of-freedom linear systems. The fundamental difference between the proposed scheme, and those that have already appeared in literature, is that it allows keeping the coordinated motion of different actuators. In other words, the use of such a scheme guarantees that a desired path in space is accurately followed while suppressing the undesired vibrational effects. The control strategy consists in actively suppressing the undesired vibrations by suitably changing the path reference for the system. Such a result can be achieved by making the path reference for the system be a function of an action reference parameter rather than just the time. The reference parameter depends on time and on a variable which plays the role of a time delay. The latter is computed on the fly, on the basis of the measured vibration. A cascade control structure is obtained, where no specific position controllers or actuators are to be employed in the inner loop.The theory developed is demonstrated through numerical simulations by applying it to the vibration and path tracking control of a four-degrees-of-freedom two-mass system.
Exploring the Mediating Mechanism Between Gender-Based Violence and Biologically Confirmed Chlamydia Among Detained Adolescent Girls
Authors: Salazar Laura F. , Crosby Richard A. , DiClemente Ralph J.
Published: January 2009

The study examined several behavioral mechanisms that link gender-based violence (GBV) to STD among detained, sexually active adolescent girls. Girls ( N = 198) were recruited from eight youth detention facilities. Measures were assessed using audiocomputer—assisted self-interviewing. DNA amplification was conducted to assess for chlamydia. Thirty-one percent had experienced GBV and 15% tested positive for chlamydia. GBV was related to chlamydia directly and indirectly through condom failures and through having sexual intercourse while high on drugs and/or alcohol. The study found that sexual risk reduction programs may benefit this population by addressing the role of GBV and its association with STD-associated behaviors.
Women's Fatalistic Suicide in Iran
Authors: Aliverdinia Akbar , Pridemore William Alex
Published: January 2009

Durkheim's theory of fatalistic suicide, or suicide resulting from overregulation of behavior, has been neglected empirically. The authors test this hypothesis in Iran by examining the geographic distribution of female suicide. Employing the province as the unit of analysis, they examine the association between female suicide rates and multiple measures of social control of women, with rates expected to be higher in areas with greater social regulation of the lives of women and stronger traditional tribal cultures. Results show that provinces with lower levels of female education, female labor force participation, and urbanization have higher female suicide rates. Thus, whereas social deregulation is often associated with higher suicide rates in the West, the authors' findings reveal that hyperregulation is associated with higher suicide rates in Iran, at least for women.
Positive and negative consequences of sick leave for the individual, with special focus on part-time sick leave
Authors: Sieurin Leif , Josephson Malin , Vingård Eva
Published: January 2009

Aims: To describe the consequences of long-term sick leave (>28 days) on working situation, health and lifestyle among employees from the public sector in Sweden. Methods: Employees in four county councils and two municipalities on long term sick leave on 1 November 2005 (n = 1,128) answered a questionnaire in February 2006. The response rate was 71.7%. Eighty seven per cent were still on sick leave when the questionnaire was answered: 54% part time and 33% full time. Results: Reporting positive consequences was rare but reporting negative consequences, such as effects on the development of salary, the possibilities of pursuing a career or to change to another job were common. Sick leave seemed to lead to a considerable loss of zest for work, even if the respondents were back in work full time. Regardless of the negative consequences at work, 92% of those on part-time sick leave believed that the part-time sick leave was good for them even if many thought it had negative consequences for employer and colleagues. Conclusions: Long-term sick leave has negative consequences for the individual in work situations, even for those back at work full time. The development of salary and career seem to be most affected. The attitude towards part-time sick leave was positive and this result indicates that there is a potential for an increased degree of partial return to work in the group of people on long-term sick leave.
Evaluation of tuberculosis control programme in Khartoum State for the year 2006
Authors: Ahmed Suleiman M.M. , Aro A.R. , Sodemann M.
Published: January 2009

Background: Tuberculosis (TB) is among the top ten causes of global mortality. Sudan is among the countries with high TB prevalence; with an estimated incidence of 90/100,000 smear-positive cases. In 1993, the Khartoum State tuberculosis control programme was established. Since its establishment, however, the programme has never been adequately assessed. Aim: To evaluate and describe the tuberculosis control programme in Khartoum State, Sudan in 2006; to find out if the programme achieved its global targeted goals; and to identify the challenges and needs for performing a good standard tuberculosis control programme. Methods: A descriptive cross-sectional and retrospective study design was used. The study population was tuberculosis control departments at the levels of the state (n = 1), localities (n = 7), health areas (n = 19) and health facilities (n = 42). Records review and group interviews were used to collect the required data. Results: The study found that the TB control programme in Khartoum State achieved a 77.2% case detection rate of the smear-postive cases, and 73.5% treatment success rate, and a case fatality rate of 2.2%, treatment failure rate of 2.2%, and default rate of 14.1%. There was no system to detect the prevalence of MDR-TB (multi-drug resistant TB) or HIV (human immunodeficiency virus) among the TB cases. The programme was not well implemented at locality or health area levels. Conversely, drugs and laboratory supply systems were functioning well. Conclusions: The tuberculosis control programme in Khartoum State is centralized, not updated, and does not achieve the targeted goals.
Designs and analyses for exploring the relationship of magnetic fields to childhood leukaemia: A pilot project for the Danish National Birth Cohort
Authors: Greenland Sander , Kheifets Leeka
Published: January 2009

Pooled analyses have consistently displayed an association of childhood leukaemia with residential magnetic fields, even after attempting to account for study problems. In light of the serious possibility that the link is indeed causal, a study of possible joint effects (interactions) of magnetic fields and genetic cofactors on childhood leukaemia may be justifiable. Such a study would face serious obstacles of limited numbers for subgroup analysis. To address these obstacles, we describe a design and analysis strategy that combines multiphase (multistage) sampling, measurement error modelling, and Bayesian methods for subgroup analysis that incorporate information from earlier pooled analyses. Special attention is given to prior specification, which would be the potentially controversial element. The approach could be pilot tested on data from the Danish National Birth Cohort, but an informative study would require augmenting these data with case-control sampling. We conclude that the approach outlined may be of value not only for this topic but also in other studies of effects of rare exposures and genetic factors on rare outcomes.
Job mismatching, unequal opportunities and long-term sickness absence in female white-collar workers in Sweden
Authors: Sandmark Hélène
Published: January 2009

Aim: To investigate associations between long-term sick-listing and factors at work and in family life. Methods: Associations were investigated in a cross-sectional case-referent study. The study base included women in white-collar jobs, aged 30—55 years, living in three urban areas in Sweden between February 2004 and October 2004. A postal questionnaire was constructed with questions on occupational and family circumstances, and sent to 513 randomly selected female white-collar workers, of whom 233 had ongoing sick-leave of 90 days or more. The response rate was 81% (n = 413). Results: Most of the women in this study were in managerial positions. The unadjusted associations showed that sick-listed women with children showed the highest estimates regarding reported long working hours, bullying, high mental strain, low control and low influence at work, and work—family imbalance. In a regression model, the strongest associations were: experiencing too high mental strain in work tasks (odds ratio (OR) = 2.57, 95% confidence interval (CI) = 2.09—3.15) and low control and influence at work (OR=2.17, 95% CI= 1.60—2.94). Sick-listed women reported an overall higher dissatisfaction with their workplace and working life. Conclusions: There seems to be a greater tendency for the sick-listed women in this study to experience low control and too high mental strain at work and to live in traditional family relationships with unequal opportunities. The women who were sick-listed were probably less able to cope with work stress and to find a balance between work and family life.
``Effectiveness'' in Finnish healthcare studies
Authors: Konu Anne , Rissanen Pekka , Ihantola Mervi , Sund Reijo
Published: January 2009

Aims: Evaluation of effectiveness is connected with prevailing paradigms, and the breadth and perspective applied therein exhibit differences. Effectiveness refers to the extent to which a given intervention or service produces health outcomes in individuals to whom it is offered. The aim of this paper is to clarify the concept of effectiveness evaluation in health care and present the ways in which Finnish healthcare studies use the concept of effectiveness. Methods: Through a systematic review of Finnish scientific journals in the healthcare research field, 25 original studies, 35 review articles, and 20 discussion papers were acquired. The inclusion criterion was that the word ``effectiveness'' was presented in the title or abstract. Results: In this study the effects of actions were evaluated through the process (outputs) or through the outcomes (harms and benefits). The word ``effectiveness'' is widely used in healthcare research in Finland; mostly in studies of orthopaedics, health services research, physiotherapy, rehabilitation, and psychiatry, yet the concept was explicitly defined in only three papers. Most studies used both process and outcome measures. The outcome indicators were usually disease-specific. Papers presenting only process outputs clearly showed a health service producer's perspective. Health-related quality of life as an outcome indicator was rarely used. Conclusions: In Finnish healthcare studies, the concept of effectiveness was rarely defined and effectiveness measures were often vague or even nonexistent. The meaning of the term had to be interpreted from the study methodology, measures, and indicators.
Understanding and interpreting the concept of physical activity — a focus group study among Swedish women
Authors: Johnson Isabel , Tillgren Per , Hagströmer Maria
Published: January 2009

Aims: Strong epidemiological evidence indicates that physical activity is highly beneficial for health. To follow physical activity trends and correctly target interventions, feasible, reliable and valid assessment methods are needed. This paper examines Swedish women's understanding and interpretations of the concepts of physical activity and exercise, as well as different intensity modifiers used in the International Physical Activity Questionnaire (IPAQ). Methods: Four focus group discussions were conducted with 27 women in total aged 35 to 69 (median = 52). Responses and accompanying discussion were analysed according to the principles for qualitative content analysis including both manifest and latent content in the text. Findings: Understanding of physical activity and exercise depends on differences in people's experiences. The women felt physical activity and exercise were different concepts, but ultimately agreed that physical activity and exercise were terms along a continuum of movement experiences, from informal to formal settings. The interpretations of the intensity modifiers ``moderate'' and ``vigorous'' were close to the formal definitions in IPAQ. However the Swedish terms ``mattligt anstraöngande'' (moderate intensity) and ''mycket anstraöngande'' (vigorous intensity) are the best possible terms and should be used in IPAQ. Conclusions: There are different interpretations of the meaning of the key concepts in IPAQ that must be considered. The use of a qualitative approach when developing physical activity questionnaires can lead to more feasible, reliable and valid assessment methods as well as a clearer message for health-enhancing physical activity recommendations.
Physical diseases among homeless people: Gender differences and comparisons with the general population
Authors: Beijer Ulla , Andréasson Sven
Published: January 2009

Aim: To study morbidity amongst homeless men and women by comparing prevalence of hospital care for somatic diseases and injuries with a control group of men and women from the general population. Methods: A cohort of 1,364 men and 340 women were documented as homeless in 1996. Comparisons are made concerning hospital care for somatic diseases and injuries (1996-2002) among 3,750 men and 1,250 women from the general population. Results: The relative risk (RR) for homeless men and women of being hospitalised was double that of the men and women in the controls (1.93 and 1.96 respectively). Homeless women had a slightly, not significant, increased risk compared to homeless men (RR 1.10). Younger homeless women had a significant higher risk. Among diagnostic categories, the highest prevalence was found among homeless men in the diagnosis group injury/poisoning (22%). The highest risk was found for skin diseases (RR 36.96) and concerned homeless women. There were a number of gender specific diagnoses, where risks were considerably elevated, such as diseases of the genital organs, viral hepatitis, and poisoning for homeless women, and cerebrovascular diseases, diseases of the liver, and concussion for homeless men. Conclusions: Homeless people had twice the risk of being hospitalised for physical diseases compared to the general population. Younger women were particularly at risk compared to homeless men and to women in the controls. There were a number of gender specific diagnoses that are important to take into account when planning services for homeless people.
Toward a New Method for Identifying Facilities and Communities With Critical Shortages of Nurses
Authors: Wing Paul , McGinnis Sandra L. , Moore Jean M.
Published: January 2009

This article summarizes the key findings of a study designed to evaluate the effectiveness of different methods for assessing the severity of nursing shortages in four types of health care facilities in the United States (hospitals, long-term care facilities, home health agencies, and public health agencies). The study involves testing several statistical models using currently available data to assess their accuracy and ease of use as possible bases for estimating and predicting the severity of nursing shortages in individual health care facilities. The assessments are based on criteria developed with the advice of panels of experts knowledgeable about each of the four types of facilities. The results of a “preferred method” for rating the severity of nursing shortages in counties in the United States are presented, along with key findings based on a variety of other models and analyses. Although it requires some refinement and a systematic validation, this method holds promise as a possible basis for targeting federal resources to alleviate the most critical nursing shortages across the country.
Ureteric Obstruction of Solitary Kidney Following Endovascular Repair of Infrarenal Abdominal Aortic Aneurysm: A Case Report
Authors: Goswami Rup , Rathod Krishnaraj , Coker Julian
Published: January 2009

Endovascular treatment of abdominal aortic aneurysm is commonplace at present. It has got lower mortality and morbidity compared to open surgical repair. However, it requires long-term follow-up. The main complications are endoleaks, stent migrations, kinks, and rupture. Ureteric obstruction is uncommon but an important complication following endovascular treatment of abdominal aortic aneurysms. We present a case of ureteric obstruction in a solitary kidney following endovascular repair of abdominal aortic aneurysm and its successful management by ureteric stenting.
Constitutive JAK3 activation induces lymphoproliferative syndromes in murine bone marrow transplantation models
Authors: Cornejo Melanie G. , Kharas Michael G. , Werneck Miriam B. , Bras Séverine Le , Moore Sandra A. , Ball Brian , Beylot-Barry Marie , Rodig Scott J. , Aster Jon C. , Lee Benjamin H. , Cantor Harvey , Merlio Jean-Philippe , Gilliland D. Gary , Mercher Thomas
Published: January 2009

The tyrosine kinase JAK3 plays a well-established role during normal lymphocyte development and is constitutively phosphorylated in several lymphoid malignancies. However, its contribution to lymphomagenesis remains elusive. In this study, we used the newly identified activating JAK3A572V mutation to elucidate the effect of constitutive JAK3 signaling on murine lymphopoiesis. In a bone marrow transplantation model, JAK3A572V induces an aggressive, fatal, and transplantable lymphoproliferative disorder characterized by the expansion of CD8+TCRαβ+CD44+CD122+Ly-6C+ T cellsthat closely resemble an effector/memory T-cell subtype. Compared with wild-type counterparts, these cells show increased proliferative capacities in response to polyclonal stimulation, enhanced survival rates with elevated expression of Bcl-2, and increased production of interferon-γ (IFNγ) and tumor necrosis factor-α (TNFα), correlating with enhanced cytotoxic abilities against allogeneic target cells. Of interest, the JAK3A572V disease is epidermotropic and produces intraepidermal microabscesses. Taken together, these clinical features are reminiscent of those observed in an uncommon but aggressive subset of CD8+ human cutaneous T-cell lymphomas (CTCLs). However, we also observed a CD4+ CTCL-like phenotype when cells are transplanted in an MHC-I–deficient background. These data demonstrate that constitutive JAK3 activation disrupts T-cell homeostasis and induces lymphoproliferative diseases in mice.
The Rac activator Tiam1 controls efficient T-cell trafficking and route of transendothelial migration
Authors: Gérard Audrey , van der Kammen Rob A. , Janssen Hans , Ellenbroek Saskia I. , Collard John G.
Published: January 2009

Migration toward chemoattractants is a hallmark of T-cell trafficking and is essential to produce an efficient immune response. Here, we have analyzed the function of the Rac activator Tiam1 in the control of T-cell trafficking and transendothelial migration. We found that Tiam1 is required for chemokine- and S1P-induced Rac activation and subsequent cell migration. As a result, Tiam1-deficient T cells show reduced chemotaxis in vitro, and impaired homing, egress, and contact hypersensitivity in vivo. Analysis of the T-cell transendothelial migration cascade revealed that PKCζ/Tiam1/Rac signaling is dispensable for T-cell arrest but is essential for the stabilization of polarization and efficient crawling of T cells on endothelial cells. T cells that lack Tiam1 predominantly transmigrate through individual endothelial cells (transcellular migration) rather than at endothelial junctions (paracellular migration), suggesting that T cells are able to change their route of transendothelial migration according to their polarization status and crawling capacity.
Cognate CD4 help is essential for the reactivation and expansion of CD8 memory T cells directed against the hematopoietic cell–specific dominant minor histocompatibility antigen, H60
Authors: Ryu Su Jeong , Jung Kyung Min , Yoo Hyun Seung , Kim Tae Woo , Kim Sol , Chang Jun , Choi Eun Young
Published: January 2009

In contrast to previous notions of the help-independency of memory CD8 T cells during secondary expansion, here we show that CD4 help is indispensable for the re-expansion of once-helped memory CD8 T cells, using a hematopoietic cell–specific dominant minor histocompatibility (H) antigen, H60, as a model antigen. H60-specific memory CD8 T cells generated during a helped primary response vigorously expanded only when rechallenged under helped conditions. The help requirement for an optimal secondary response was confirmed by a reduction in peak size by CD4 depletion, and was reproduced after skin transplantation. Helpless conditions or noncognate separate help during the secondary response resulted in a significant reduction in the peak size and different response kinetics. Providing CD4 help again during a tertiary challenge restored robust memory expansion; however, the repeated deprivation of help further reduced clonal expansion. Adoptively transferred memory CD8 T cells did not proliferate in CD40L−/− hosts. In the CD40−/− hosts, marginal memory expansion was detected after priming with male H60 cells but was completely abolished by priming with peptide-loaded CD40−/− cells, suggesting the essential role of CD40 and CD40L in memory responses. These results provide insight into the control of minor H antigen-specific CD8 T-cell responses, to maximize the graft-versus-leukemia response.
Insights into the manifestations, outcomes, and mechanisms of leukemogenesis in Down syndrome
Authors: Malinge Sébastien , Izraeli Shai , Crispino John D.
Published: January 2009

Children with Down syndrome (DS) show a spectrum of clinical anomalies, including cognitive impairment, cardiac malformations, and craniofacial dysmorphy. Moreover, hematologists have also noted that these children commonly show macrocytosis, abnormal platelet counts, and an increased incidence of transient myeloproliferative disease (TMD), acute megakaryocytic leukemia (AMKL), and acute lymphoid leukemia (ALL). In this review, we summarize the clinical manifestations and characteristics of these leukemias, provide an update on therapeutic strategies and patient outcomes, and discuss the most recent advances in DS-leukemia research. With the increased knowledge of the way in which trisomy 21 affects hematopoiesis and the specific genetic mutations that are found in DS-associated leukemias, we are well on our way toward designing improved strategies for treating both myeloid and lymphoid malignancies in this high-risk population.
Robust discovery of periodically expressed genes using the laplace periodogram
Authors: Liang Kuo-ching , Wang Xiaodong , Li Ta-Hsin
Published: January 2009

Background

Time-course gene expression analysis has become important in recent developments due to the increasingly available experimental data. The detection of genes that are periodically expressed is an important step which allows us to study the regulatory mechanisms associated with the cell cycle.

Results

In this work, we present the Laplace periodogram which employs the least absolute deviation criterion to provide a more robust detection of periodic gene expression in the presence of outliers. The Laplace periodogram is shown to perform comparably to existing methods for the Sacharomyces cerevisiae and Arabidopsis time-course datasets, and to outperform existing methods when outliers are present.

Conclusion

Time-course gene expression data are often noisy due to the limitations of current technology, and may include outliers. These artifacts corrupt the available data and make the detection of periodicity difficult in many cases. The Laplace periodogram is shown to perform well for both data with and without the presence of outliers, and also for data that are non-uniformly sampled.
Cell and molecular mechanisms of keratinocyte function stimulated by insulin during wound healing
Authors: Liu Yan , Petreaca Melissa , Yao Min , Martins-Green Manuela
Published: January 2009

Background

Regenerative wound repair is a goal of modern medicine. This is important not only for the local repair but also for its beneficial effect to systemic physiological processes. When wounds become chronic, individuals are susceptible to generalized inflammatory cascades that can affect many organs and even lead to death. Skin is the most commonly injured tissue, and its proper repair is important for reestablishment of its barrier function.

Results

We show here that insulin, when topically applied to skin excision wounds, accelerates re-epithelialization and stimulates "maturation" of the healing tissue. These effects are dependent on the insulin receptor but independent of EGF/EGF-R; PI3K-Akt-Rac1 signaling pathways are critically involved, and healing is α3 and LN332-dependent.

Conclusion

Insulin has great potential for the treatments of chronic wounds in which re-epthelialization is impaired. Understanding of the pathways induced by insulin is important for the development of analog molecules that function strictly in healing. Because of its long history of safe use in humans for decades, this protein may prove to be a powerful therapy without major adverse effects.
Evolution of prokaryotic SPFH proteins
Authors: Hinderhofer Markus , Walker Christina A , Friemel Anke , Stuermer Claudia AO , Möller Heiko M , Reuter Alexander
Published: January 2009

Background

The SPFH protein superfamily is a diverse family of proteins whose eukaryotic members are involved in the scaffolding of detergent-resistant microdomains. Recently the origin of the SPFH proteins has been questioned. Instead, convergent evolution has been proposed. However, an independent, convergent evolution of three large prokaryotic and three eukaryotic families is highly unlikely, especially when other mechanisms such as lateral gene transfer which could also explain their distribution pattern have not yet been considered.

To gain better insight into this very diverse protein family, we have analyzed the genomes of 497 microorganisms and investigated the pattern of occurrence as well as the genomic vicinity of the prokaryotic SPFH members.

Results

According to sequence and operon structure, a clear division into 12 subfamilies was evident. Three subfamilies (SPFH1, SPFH2 and SPFH5) show a conserved operon structure and two additional subfamilies are linked to those three through functional aspects (SPFH1, SPFH3, SPFH4: interaction with FtsH protease). Therefore these subgroups most likely share common ancestry. The complex pattern of occurrence among the different phyla is indicative of lateral gene transfer. Organisms that do not possess a single SPFH protein are almost exclusively endosymbionts or endoparasites.

Conclusion

The conserved operon structure and functional similarities suggest that at least 5 subfamilies that encompass almost 75% of all prokaryotic SPFH members share a common origin. Their similarity to the different eukaryotic SPFH families, as well as functional similarities, suggests that the eukaryotic SPFH families originated from different prokaryotic SPFH families rather than one. This explains the difficulties in obtaining a consistent phylogenetic tree of the eukaryotic SPFH members. Phylogenetic evidence points towards lateral gene transfer as one source of the very diverse patterns of occurrence in bacterial species.
Expression profiles of urbilaterian genes uniquely shared between honey bee and vertebrates
Authors: Matsui Toshiaki , Yamamoto Toshiyuki , Wyder Stefan , Zdobnov Evgeny M , Kadowaki Tatsuhiko
Published: January 2009

Background

Large-scale comparison of metazoan genomes has revealed that a significant fraction of genes of the last common ancestor of Bilateria (Urbilateria) is lost in each animal lineage. This event could be one of the underlying mechanisms involved in generating metazoan diversity. However, the present functions of these ancient genes have not been addressed extensively. To understand the functions and evolutionary mechanisms of such ancient Urbilaterian genes, we carried out comprehensive expression profile analysis of genes shared between vertebrates and honey bees but not with the other sequenced ecdysozoan genomes (honey bee-vertebrate specific, HVS genes) as a model.

Results

We identified 30 honey bee and 55 mouse HVS genes. Many HVS genes exhibited tissue-selective expression patterns; intriguingly, the expression of 60% of honey bee HVS genes was found to be brain enriched, and 24% of mouse HVS genes were highly expressed in either or both the brain and testis. Moreover, a minimum of 38% of mouse HVS genes demonstrated neuron-enriched expression patterns, and 62% of them exhibited expression in selective brain areas, particularly the forebrain and cerebellum. Furthermore, gene ontology (GO) analysis of HVS genes predicted that 35% of genes are associated with DNA transcription and RNA processing.

Conclusion

These results suggest that HVS genes include genes that are biased towards expression in the brain and gonads. They also demonstrate that at least some of Urbilaterian genes retained in the specific animal lineage may be selectively maintained to support the species-specific phenotypes.
Acidithiobacillus ferrooxidans metabolism: from genome sequence to industrial applications
Authors: Valdés Jorge , Pedroso Inti , Quatrini Raquel , Dodson Robert J , Tettelin Herve , Blake Robert , Eisen Jonathan A , Holmes David S
Published: January 2009

Background

Acidithiobacillus ferrooxidans is a major participant in consortia of microorganisms used for the industrial recovery of copper (bioleaching or biomining). It is a chemolithoautrophic, γ-proteobacterium using energy from the oxidation of iron- and sulfur-containing minerals for growth. It thrives at extremely low pH (pH 1–2) and fixes both carbon and nitrogen from the atmosphere. It solubilizes copper and other metals from rocks and plays an important role in nutrient and metal biogeochemical cycling in acid environments. The lack of a well-developed system for genetic manipulation has prevented thorough exploration of its physiology. Also, confusion has been caused by prior metabolic models constructed based upon the examination of multiple, and sometimes distantly related, strains of the microorganism.

Results

The genome of the type strain A. ferrooxidans ATCC 23270 was sequenced and annotated to identify general features and provide a framework for in silico metabolic reconstruction. Earlier models of iron and sulfur oxidation, biofilm formation, quorum sensing, inorganic ion uptake, and amino acid metabolism are confirmed and extended. Initial models are presented for central carbon metabolism, anaerobic metabolism (including sulfur reduction, hydrogen metabolism and nitrogen fixation), stress responses, DNA repair, and metal and toxic compound fluxes.

Conclusion

Bioinformatics analysis provides a valuable platform for gene discovery and functional prediction that helps explain the activity of A. ferrooxidans in industrial bioleaching and its role as a primary producer in acidic environments. An analysis of the genome of the type strain provides a coherent view of its gene content and metabolic potential.
Paxillin-Y118 phosphorylation contributes to the control of Src-induced anchorage-independent growth by FAK and adhesion
Authors: Sachdev Sanjay , Bu Yahao , Gelman Irwin H
Published: January 2009

Background

Focal adhesion kinase (FAK) and Src are protein tyrosine kinases that physically and functionally interact to facilitate cancer progression by regulating oncogenic processes such as cell motility, survival, proliferation, invasiveness, and angiogenesis.

Method

To understand how FAK affects oncogenesis through the phosphorylation of cellular substrates of Src, we analyzed the phosphorylation profile of a panel of Src substrates in parental and v-Src-expressing FAK+/+ and FAK-/- mouse embryo fibroblasts, under conditions of anchorage-dependent (adherent) and -independent (suspension) growth.

Results

Total Src-induced cellular tyrosine phosphorylation as well as the number of phosphotyrosyl substrates was higher in suspension versus adherent cultures. Although the total level of Src-induced cellular phosphorylation was similar in FAK+/+ and FAK-/- backgrounds, the phosphorylation of some substrates was influenced by FAK depending on adherence state. Specifically, in the absence of FAK, Src induced higher phosphorylation of p190RhoGAP, paxillin (poY118) and Crk irrespective of adhesion state, PKC-δ (poY311), connexin-43 (poY265) and Sam68 only under adherent conditions, and p56Dok-2 (poY351) and p120catenin (poY228) only under suspension conditions. In contrast, FAK enhanced the Src-induced phosphorylation of vinculin (poY100 and poY1065) and p130CAS (poY410) irrespective of adherence state, p56Dok-2 (poY351) and p120catenin (poY228) only under adherent conditions, and connexin-43 (poY265), cortactin (poY421) and paxillin (poY31) only under suspension conditions. The Src-induced phosphorylation of Eps8, PLC-γ1 and Shc (poY239/poY240) were not affected by either FAK or adherence status. The enhanced anchorage-independent growth of FAK-/-[v-Src] cells was selectively decreased by expression of paxillinY118F, but not by WT-paxillin, p120cateninY228F or ShcY239/240F, identifying for the first time a role for paxillinpoY118 in Src-induced anchorage-independent growth. Knockdown of FAK by siRNA in the human colon cancer lines HT-25 and RKO, resulted in increased paxillinpoY118 levels under suspension conditions as well as increased anchorage-independent growth, supporting the notion that FAK attenuates anchorage-independent growth by suppressing adhesion-dependent phosphorylation of paxillinY118.

Conclusion

These data suggest that phosphorylation of Src substrates is a dynamic process, influenced temporally and spatially by factors such as FAK and adhesion.