bluuebunny/crossref_metadata_2025 huggingface dataset:
Origins of the “Black/White” Difference in Blood Pressure
Authors: Cruickshank J.K. , Mzayek F. , Liu L. , Kieltyka L. , Sherwin R. , Webber L.S. , Srinavasan S.R. , Berenson G.S.
Published: April 2005

Background—

The determinants of differences in blood pressure that emerge in adolescence between black Americans of predominantly African descent and white Americans of predominantly European descent are unknown. One hypothesis is related to intrauterine and early childhood growth. The role of early blood pressure itself is also unclear. We tested whether differences in birth weight and in carefully standardized subsequent measures of weight, height, and blood pressure from 0 to 4 or 5 years were related to black/white differences in blood pressure in adolescence.

Methods and Results—

Two Bogalusa cohorts who had complete follow-up data on birth weights and early childhood and adolescent anthropometric and blood pressure measures were pooled. One hundred eighty-five children (48 black and 47 white boys and 41 black and 49 white girls) were followed up and studied after 15 to 17 years. Birth weights were a mean 443 and 282 g lower in black boys and girls, respectively, than in whites (
P
<0.001). Blood pressures in adolescence were 3.4/1.9 and 1.7/0.6 mm Hg higher, respectively, and tracked from early childhood. In regression analyses, birth weight accounted for the ethnic difference in adolescent blood pressure, which was also independently predicted, in decreasing impact order, by adolescent height, adolescent body mass index, and systolic blood pressure at 4 to 5 years and inversely by growth from 0 to 4 to 5 years.

Conclusions—

If these results can be replicated in larger and independent samples, they suggest that efforts to improve intrauterine growth in black infants as well as lessen weight gain in adolescence might substantially reduce excess high blood pressure/hypertension in this ethnic group.
Novel Mitogenic Effect of Adenosine on Coronary Artery Smooth Muscle Cells
Authors: Shen Jianzhong , Halenda Stephen P. , Sturek Michael , Wilden Peter A.
Published: April 2005

Adenosine is a vascular endothelial cell mitogen, but anti-mitogenic for aortic smooth muscle cells and fibroblasts when acting via the A
2B
adenosine receptor. However, we show that adenosine increases porcine coronary artery smooth muscle cell (CASMC) number, cellular DNA content, protein synthesis, and PCNA staining. RT-PCR analysis indicates that porcine CASMC express A
1
, A
2A
, A
3
, and barely detectable levels of A
2B
receptor mRNAs. The mitogenic effect of adenosine is mimicked by NECA, CCPA, and R-PIA, but not by CGS21680 and 2-Cl-IB-MECA, and is inhibited by DPCPX, indicating a prominent role for the A
1
receptor. This interpretation is supported by the finding that adenosine- and CCPA-induced DNA synthesis is significantly inhibited by pertussis toxin, but substantially potentiated by PD81723, an allosteric enhancer of the A
1
receptor. When a cDNA encoding the porcine A
1
receptor was cloned and expressed in COS-1 cells, A
1
receptor pharmacology is confirmed. Anti-sense oligonucleotides to the cloned sequence dramatically suppress the mitogenic effect of adenosine and CCPA. Conversely, over-expression of the cloned A
1
receptor in CASMC increases adenosine- and CCPA-induced DNA synthesis. Furthermore, stimulation with adenosine or CCPA of intact coronary arteries in an organ culture model of vascular disease increases cellular DNA synthesis, which was abolished by DPCPX. We conclude that adenosine acts as a novel mitogen in porcine CASMC that express the A
1
adenosine receptor, possibly contributing to the development of coronary artery disease.
Adenovirus Vector E4 Gene Regulates Connexin 40 and 43 Expression in Endothelial Cells via PKA and PI3K Signal Pathways
Authors: Zhang Fan , Cheng Joseph , Lam George , Jin David K. , Vincent Loïc , Hackett Neil R. , Wang Shiyang , Young Lauren M. , Hempstead Barbara , Crystal Ronald G. , Rafii Shahin
Published: April 2005

Connexins (Cxs) provide a means for intercellular communication and play important roles in the pathophysiology of vascular cardiac diseases. Infection of endothelial cells (ECs) with first-generation E1/E3-deleted E4
+
adenovirus (AdE4
+
) selectively modulates the survival and angiogenic potential of ECs by as of yet unrecognized mechanisms. We show here that AdE4
+
vectors potentiate Cx expression in ECs in vitro and in mouse heart tissue. Infection of ECs with AdE4
+
, but not AdE4
−
, resulted in a time- and dose-dependent induction of junctional Cx40 expression and suppression of Cx43 protein and mRNA expression. Treatment of ECs with PKA inhibitor H89 or PI3K inhibitor LY294002 prevented the AdE4
+
-mediated regulation of Cx40 and Cx43 that was associated with diminished AdE4
+
-mediated survival of ECs. Moreover, both PKA activity and cAMP-response element (CRE)-binding activity were enhanced by treatment of ECs with AdE4
+
. However, there is no causal evidence of a cross-talk between the 2 modulatory pathways, PKA and PI3K. Remarkably, Cx40 immunostaining was markedly increased and Cx43 was decreased in the heart tissue of mice treated with intra-tracheal AdE4
+
. Taken together, these results suggest that AdE4
+
may play an important role in the regulation of Cx expression in ECs, and that these effects are mediated by both the PKA/CREB and PI3K signaling pathways.
Angiotensin IV Activates the Nuclear Transcription Factor-κB and Related Proinflammatory Genes in Vascular Smooth Muscle Cells
Authors: Esteban Vanesa , Ruperez Mónica , Sánchez-López Elsa , Rodríguez-Vita Juan , Lorenzo Oscar , Demaegdt Heidi , Vanderheyden Patrick , Egido Jesús , Ruiz-Ortega Marta
Published: April 2005

Inflammation is a key event in the development of atherosclerosis. Nuclear factor-κB (NF-κB) is important in the inflammatory response regulation. The effector peptide of the renin angiotensin system Angiotensin II (Ang II) activates NF-κB and upregulates some related proinflammatory genes. Our aim was to investigate whether other angiotensin-related peptides, as the N-terminal degradation peptide Ang IV, could regulate proinflammatory factors (activation of NF-κB and related genes) in cultured vascular smooth muscle cells (VSMCs). In these cells, Ang IV increased NF-κB DNA binding activity, caused nuclear translocation of p50/p65 subunits, cytosolic IκB degradation and induced NF-κB–dependent gene transcription. Ang II activates NF-κB via AT
1
and AT
2
receptors, but AT
1
or AT
2
antagonists did not inhibit NF-κB activation caused by Ang IV. In VSMC from AT
1a
receptor knockout mice, Ang IV also activated NF-κB pathway. In those cells, the AT
4
antagonist divalinal diminished dose-dependently Ang IV–induced NF-κB activation and prevented IκB degradation, but had no effect on the Ang II response, indicating that Ang IV activates the NF-κB pathway via AT
4
receptors. Ang IV also increased the expression of proinflammatory factors under NF-κB control, such as MCP-1, IL-6, TNF-α, ICAM-1, and PAI-1, which were blocked by the AT
4
antagonist. Our results reveal that Ang IV, via AT
4
receptors, activates NF-κB pathway and increases proinflammatory genes. These data indicate that Ang IV possesses proinflammatory properties, suggesting that this Ang degradation peptide could participate in the pathogenesis of cardiovascular diseases.
Use of Functional MRI to Guide Decisions in a Clinical Stroke Trial
Authors: Cramer Steven C. , Benson Randall R. , Himes David M. , Burra Vijaya C. , Janowsky Jeri S. , Weinand Martin E. , Brown Jeffrey A. , Lutsep Helmi L.
Published: April 2005

Background and Purpose—

An investigational trial examined safety and efficacy of targeted subthreshold cortical stimulation in patients with chronic stroke. The anatomical location for the target, hand motor area, varies across subjects, and so was localized with functional MRI (fMRI). This report describes the experience of incorporating standardized fMRI into a multisite stroke trial.

Methods—

At 3 enrollment centers, patients moved (0.25 Hz) the affected hand during fMRI. Hand motor function was localized at a fourth center guiding intervention for those randomized to stimulation.

Results—

The fMRI results were available within 24 hours. Across 12 patients, activation site variability was substantial (12, 23, and 11 mm in x, y, and z directions), exceeding stimulating electrode dimensions.

Conclusion—

Use of fMRI to guide decision-making in a clinical stroke trial is feasible.
Partisanship and the Path to Financial Openness
Authors: Kastner Scott L. , Rector Chad
Published: April 2005

The effect of traditional left-right economic preferences on countries’ international financial openness is more subtle than existing studies have recognized. The authors investigate the role that partisan politics played in the liberalization of international financial markets within 12 Western European democracies from 1960 to 1986. The authors find that right governments tended to be active liberalizers of the capital account. They were more likely than left governments to enact liberalizations, and liberalizations were especially likely when new right governments entered office. Left governments typically acquiesced to these changes. Although less likely to enact liberalizations, they were no more likely to impose new restrictions. The authors’ findings are consistent with studies that show how financial integration does not undermine welfare states but is still subject to partisan contention.
Information Technology, Public Space, and Collective Action in China
Authors: Zheng Yongnian , Wu Guoguang
Published: April 2005

The Internet has stimulated academic inquiries on the political implications of the Internet revolution. A great deal of attention has been focused on the following: Has the Internet altered the nature of interaction between the state and society? Will the Internet ultimately be able to promote the democratic transition of existing authoritarian political systems? This article attempts to address these two questions based on an empirical study of the situation in China. The article explores the democratic implications of the Internet in the context of the interplay between the state and society by setting up a three-layered analytical framework, that is, the Internet as a tool for communication, the Internet as public space, and the Internet as a means for collective action. In China, the impact of the Internet on democratic transition differs at each of these three layers, depending on the interaction strategies between the state and society.
Trust and Political Economy
Authors: Farrell Henry
Published: April 2005

Cooperation between small firms in “industrial districts,” where the production process may be radically dis-integrated, poses an important challenge to current political science theories of trust and cooperation. In this article, the author suggests that the problems posed by these districts—the existence of apparently irrational forms of trust in the political economy and of high-trust forms of cooperation in societies with low levels of interpersonal trust—may be explained if one adopts a more sophisticated institutional approach. The author shows how institutions may affect trust between economic actors and thus cooperation in two case studies of industrial districts, mechanical engineering in Bologna, Italy, and Stuttgart, Germany, and shows that empirical evidence supports the hypothesis that trust may depend on institutions and vary with institutional context.
Putting Stereotype Content in Context: Image Theory and Interethnic Stereotypes
Authors: Alexander Michele G. , Brewer Marilynn B. , Livingston Robert W.
Published: April 2005

Two studies apply intergroup image theory to better understand divergent interethnic images and to highlight the important role of intergroup context and perceived intergroup relations in shaping the content of social stereotypes. Image theory hypothesizes that specific interethnic stereotypes arise from specific patterns of perceived intergroup competition, relative power, and relative cultural status. Results from surveying Black, White, and Native Americans’ appraisals of intergroup relations and reported outgroup stereotypes in various intergroup contexts suggest that the content of outgroup stereotypes varies systematically as a function of the perceived state of intergroup relations and the intergroup context in which these groups are situated. The data reported from both studies establish the importance of examining social stereotypes from a functional perspective in the context of intergroup relations.
Connecting the Horizontal Dimension of Social Comparison With Self-Worth and Self-Confidence
Authors: Locke Kenneth D.
Published: April 2005

Multilevel modeling of undergraduates (N = 229) event-contingent records of naturalistic social comparison experiences revealed distinct correlates of the horizontal (similar-different) dimension and vertical (better-worse) dimension of comparisons. Complementing past studies showing associations between the horizontal dimension and communal dispositions and experiences, the current study showed that the horizontal dimension also is associated with agentic dispositions and experiences such as self-worth and self-confidence. For example, participants perceived more similarity when comparing with targets’ desirable attributes than with targets’ undesirable attributes and perceiving similarities with desirable target attributes (and dissimilarities with undesirable target attributes) enhanced their self-confidence. Participants higher in self-worth (high in self-esteem and low in depression) were more discriminating in their experiences of similarity and connection; specifically, they reported more similarity and connection when targets’ attributes were desirable but less connection the more targets’ attributes were inferior to their own.
Do Unto Others as They Do Unto You: Reciprocity and Social Identification as Determinants of Ingroup Favoritism
Authors: Stroebe Katherine , Lodewijkx Hein F.M. , Spears Russell
Published: April 2005

Predictions from the bounded and unbounded reciprocity hypotheses and from social identity theory (SIT) were examined in a minimal group experiment in which ingroup outcome dependence, outgroup outcome dependence, and the strength of social identity were orthogonally manipulated. Both ingroup and outgroup outcome dependence affected reward allocations. Participants made more ingroup-favoring reward allocations across all conditions. The identification manipulation produced hypothesized effects on social identification measures and marginal effects of identification on reward allocations in the no-dependence condition. Support was found for both an unbounded and bounded version of the reciprocity hypothesis and marginal support for a SIT approach to intergroup discrimination. The study highlights insufficiencies of both theoretical approaches and suggests possibilities for integration and elaboration.
Maintenance and Decay of Past Behavior Influences: Anchoring Attitudes on Beliefs Following Inconsistent Actions
Authors: Albarracín Dolores , McNatt Penny S.
Published: April 2005

Three studies investigated the influence of past behavior on the stability of the attitudes it elicits. In Experiment 1, the effect of a bogus behavior feedback was long lasting when people engaged in biased scanning, presumably because this process elicits behavior-consistent beliefs. In contrast, the effect of the feedback decayed when participants were forced to consider whether the behavior might have undesirable outcomes. A second experiment using a different behavioral paradigm and a field study further supported the interpretation that individuals resolve conflict between a past behavior and subsequent beliefs about it by aligning attitudes with beliefs instead of behavior.
Temporal Dimensions of Conversational Interaction
Authors: Boltz Marilyn G.
Published: April 2005

Four experiments examined whether variations in response latencies to a speaker’s query can be used to infer certain characteristics of a respondent. Across all experiments, participants listened to a set of monologues that varied in their underlying speech act (honesty, confidence, certainty, compliance). In Experiment 1, participants were asked to produce a designated one-word response to each monologue with the latency that conveyed either the most favorable or unfavorable impression. Experiment 2 relied on a perceptual rating task and confirmed that those latencies produced to express the most positive and negative impressions were in fact perceived as such by an independent group of participants. More important, the acceptance range of response latency behavior varied with different speech acts and evaluative dimensions. Experiments 3 and 4 extended these findings by revealing that the duration of inter-sentence pauses of a speaker’s monologue appears to be the primary determinant of response timing behavior. As a set, these results suggest that people adopt different criteria when judging different types of potential deception and this in turn can be facilitated by processes related to speaker accommodation.
Sexual Motives and Sentencing
Authors: MacMartin Clare , Wood Linda A.
Published: April 2005

The motives ascribed to offenders in the sentencing of sexual abuse crimes can be highly contentious. Some critics claim that sexual assaults are acts of power and violence and that reference to sexual motives minimizes violence and the seriousness of the offense. The present study examines 74 Canadian judicial sentencing decisions (1993-1997) involving offenders who had sexually abused children and adolescents. Using discursive social psychology, the authors analyze judicial explanations for the offenses, and their implications for mitigation and aggravation. Violent attributions were rare. Sex-based explanations predominated, variously invoking the selfish gratification of offenders’ sexual desires, sexual impulses, pedophilia, and offenders’ attraction to victims. However, in contrast to critics’ claims, these explanations are used by judges to emphasize the seriousness of these crimes. The findings highlight the importance of analyzing discourse in relation to action sequences rather than in isolation. The authors discuss the implications for the study of sexual assault and legal discourse.
Interpretations of Messages
Authors: Bello Richard , Edwards Renee
Published: April 2005

Equivocation, the use of ambiguity or vagueness, is used to protect face when an interlocutor seeks to avoid a hurtful truth or a deception. This study compared the effects of self and other-face, sex, and several versions of equivocation on perceptions of messages. Participants (n = 354) read a scenario about a public-speaking situation in which a classmate makes a comment about a poor performance. Equivocation, especially that directed at other-face, is judged more polite than unequivocal criticism. Unequivocal criticism is judged as more competent and honest than equivocation. A mixed message is regarded the most positively.
Readers’ Perceptions of Author Gender and Literary Genre
Authors: Janssen Anna , Murachver Tamar
Published: April 2005

Objective analyses of the language used in published literature have revealed effects of both author gender and literary genre. It is unclear, however, whether readers are sensitive to these differences. Participants’ ratings of author gender and literary genre were evaluated against actual gender and genre and statistically predicted gender and genre. Statistical predictions of gender and genre were based solely upon the authors’ use of a selection of gender-preferential language features. Overall, participants were far more adept at judging author gender than genre. They were also more accurate in judging male than female authorship. Judgments of author gender were more closely aligned with actual than statistically predicted gender. This suggests that authors display their gender in ways that extend beyond the specific language features they employ. In showing this, the study helps explain why gender is often difficult for authors to hide and for readers to ignore.
Season- and Latitude-Dependent Effects of Simulated Twilights on Circadian Entrainment
Authors: Boulos Ziad , Macchi M. Mila
Published: April 2005

Groups of Syrian hamsters were exposed to LD cycles with twilight transitions and photoperiods simulating natural lighting conditions at the summer solstice (SS), equinox, and winter solstice (WS) at 41°N and at the winter solstice at the Arctic Circle (WS 66°N) but with daytime illuminance truncatedat10 lux (LD-twilight). Separate groups were kept under matching rectangular cycles (LD-rectangular). The inclusion of twilights affected several circadian parameters in a season-and latitude-dependent manner. The most striking difference was in the timing of activity onsets, which followed dusk in the presence of twilights but were more closely related to dawn (lights-on) in their absence. Activity offsets and midpoints were also earlier in LD-twilight than in LD-rectangular, with the differences being most pronounced under WS 66°N. In LD-twilight, longer nights resulted in earlier offsets and midpoints, but in LD-rectangular, midpoints were later under long than under short nights while offsets did not vary significantly. In LD-twilight, activity duration (alpha) increased monotonically with increasing nighttime duration, but in LD-rectangular, alpha was shorter under WS 66°N than under WS conditions. These effects of season and latitude observed in LD-twilight were similar to those reported in animals exposed to natural illumination, while those observed in LD-rectangular differed in several respects. The presence of twilights also resulted in lower day-to-day variability in activity onset times (greater precision), supporting the earlier conclusion that twilights increase the strength of the LD zeitgeber. Free-running periods in constant darkness (DD) were shorter in LD-twilight than in LD-rectangular, especially under WS 66°N, raising the possibility that the effects of twilights on the timing of the entrained activity rhythm reflect their effects on the period of that rhythm. Increasing daytime illuminance to 100 lux (WS conditions only) resulted in earlier activity offsets and midpoints and a shorter alpha but had no effect on activity onsets or on subsequent period in DD. These results indicate that exposure to low twilight illuminances alone can account for several of the documented differences between the effects of natural and rectangular light cycles on circadian entrainment.
Importance of Photoperiods in the Regulation of Ovarian Activities in Indian Major Carp Catla catla in an Annual Cycle
Authors: Dey Ruma , Bhattacharya Sharmistha , Maitra Saumen Kumar
Published: April 2005

The present study attempted for the first time to explore the importance of photoperiod in the regulation of seasonal ovarian functions in any subtropical major carp. Adult Indian major carp Catla catla were transferred to a long photoperiod (LP; LD 16:8) or a short photoperiod (SP; LD 8:16) for 30 days on 4 dates corresponding to the beginnings of 4 reproductive phases in an annual cycle, and responsiveness of the ovary was evaluated by comparison with the gonadal weight (IG), relative number of developing oocytes, serum levels of vitellogenin, and the activity of 2 important steroidogenic enzymes, that is, Δ53β-hydroxysteroid dehydrogenase and 17.β-hydroxysteroid dehydrogenase, in the ovary of fish in a natural photoperiod. Exposure of fish to LP during the preparatory phase (February-March) resulted in a significant ( p < 0.001) increase in the values of vitellogenin and in the activity of both the steroidogenic enzymes but not in the ovarian weight and in the relative number of different stages of oocytes. A more stimulatory influence of LP was noted during the prespawning phase (April-May), when precocious maturation of ovary was evident from a significant ( p < 0.001) rise in the values of each studied features of ovarian functions. However, no ovarian response was found when the fish were transferred to LP during the spawning (July-August) and the postspawning (September-October) phases. On the other hand, the SP was found to have an inhibitory influence on ovarian growth and maturation during the prespawning and the spawning phases or to have no influences on ovarian functions during the preparatory and the postspawning phases of an annual cycle. The results of our study provide the first evidence that photoperiod per se plays an important role in the seasonal maturation of ovary in a subtropical freshwater major carp.
Phenomenology and Meaning Making: Student Voices and Understandings of Cultural Difference
Authors: Westrick Jan Marie
Published: April 2005

The purpose of this study is to examine international school secondary students’ understandings of intercultural sensitivity and the life experiences they attribute as influencing their own development of intercultural sensitivity, including participation in four models of service programs offered at their school. With practitioners in the field of service-learning claiming that service-learning influences students’ personal development, this study uses semistructured interviews and qualitative analysis to gain insights from students’ perspectives about the influence of participation in service-learning programs and other life factors on their intercultural sensitivity. This study found that international school students have many formal and informal opportunities to experience difference; that although service-learning can influence the development of intercultural sensitivity, it does not necessarily do so; and that students are able to develop intercultural sensitivity through a variety of life experiences.
Marketing Australian Universities to Thai Students
Authors: Pimpa Nattavud
Published: April 2005

This study examines Thai students’ perceptions regarding the quality of the Australian university system. Research findings reveal that (a) it is very important to maintain and safeguard the university’s superior reputation, as it is the most important factor influencing Thais to choose one university over other institutions; (b) information on the university, campuses, academic courses, subjects, and services for international students should be easy to access because Thai students always look at this information as part of the quality of the institution; and (c) Thai students from different levels of education perceived the quality of international education in different ways, thus, the need for international education and the decision-making process of each group of Thai students are dissimilar. This information affords stakeholders marketing international educational institutions a better understanding of choices made by Thai students.
Behaviour of Ir–24 at.-%Ta films on Ni based single crystal superalloys
Authors: Kuppusami P. , Murakami H. , Ohmura T.
Published: April 2005

The properties of Ir–24Ta (at.-%) films prepared by dc magnetron cosputtering from a composite target on a 〈 100 〉 oriented Ni based single crystal superalloy TMS-75 were investigated. Ir–Ta was proposed as a novel oxidation resistant bond coat material for thermal barrier coatings. XRD showed the formation of a Ir-Ta fcc phase with a fibre texture with 〈 111 〉 orientation tilted by ∼ 10° with respect to the plane normal to the substrate surface. The Ir–Ta film subjected to post-heat treatment was found to be very stable, with no secondary phase formation up to 1073 K, and there seems to be interdiffusion at 1273 K. Nanoindentation measurements indicated that the addition of tantalum decreased Young's modulus and increased the hardness obtained in the as deposited films compared with the hardness of iridium films. The Ir–Ta films heat treated up to 1273 K also exhibited nanomechanical properties comparable with those of as deposited films at 573 K.
Effect of alumina content on wear behaviour of Ni−P−Al2O3(α) electroless composite coatings
Authors: Alirezaei S. , Monirvaghefi S.M. , Salehi M. , Saatchi A. , Kargosha M.
Published: April 2005

Codeposition of alumina particles within a Ni–P matrix was investigated. These composite coatings were produced on AISI 1045 steel discs by an electroless process and then heat treated at 200, 400 and 600°C for 1 h. Wear resistance of the deposits was measured by the pin on disc method. Structural changes were evaluated by X-ray diffraction (XRD) analysis, and SEM was used to study the surface morphology, cross-sections of coatings, wear surfaces and debris. The volume of codeposited particles was determined using an image analysis system. The results showed that alumina content in the bath to 15 g L−1 led to an increase in both the hardness and the wear resistance of the coatings. It was also found that heat treatment at about 400°C can increase the hardness and wear resistance of these composite coatings to maximum values.
Effect of DLC coatings on wear in automotive applications
Authors: Johnston S. V. , Hainsworth S. V.
Published: April 2005

Diamond like carbon (DLC) coatings have been investigated for application in the automotive valve train and, in particular, the camshaft drive assembly. The drive assembly can have various force transfer devices, such as an overhead bucket tappet assembly or a cam follower assembly. Force transfer devices operate in severe tribological contact situations with maximum Hertzian stresses approaching 1 GN m−2 and temperatures in the range 100–150°C. Lubrication is often partially starved and, therefore, the thermochemical properties and surface finish of the components are critical to their successful operation. For motor sport applications, DLC offers improved wear resistance over steel alone; and for passenger vehicles, the high hardness and commensurately lower friction coefficient that DLC gives against steel counterfaces offers improvements in fuel economy and lower wear. This paper presents the results from an investigation of the wear of DLC coated shims against standard production camshafts. DLC offers benefits in terms of reducing shim wear, but increases the wear of the camshaft. The wear mechanism observed for DLC is dependent on the oil type, but generally it is a pitting type mechanism. The cam wear occurs by plastic ratchetting. The consequences of the results are discussed in terms of the implementation of such coatings in standard valve train applications.
Investigation of carbon void defects on hard disk surfaces
Authors: Zhong Z. W. , Gee S. H.
Published: April 2005

A carbon void on a hard disk surface is a defect that occurs during the carbon sputter deposition process for the manufacture of hard disks. Because the carbon overcoat on hard disk surfaces acts as a barrier to corrosion, it is essential to reduce the number and size of carbon voiddefects. In the present study, carbon void defects on hard disk surfaces were studied using various failure analysis tools. The influence of the substrate bias voltage on the number and size of carbon void defects was also investigated. The results of the failure analysis show that there wasa 40–50% loss in recorded magnetic bit signal due to an increase in the gap between a recording head and a hard disk surface with carbon void defects. Removing the bias voltage on the substrate during the sputtering process reduced the carbon void defects significantly. The average numberof carbon void defects per disk surface was reduced from 4 to 0·5. In addition, the average size of the carbon void defect was reduced from 8 μm to 3·8 μm.
Surface coating of particles by nanospray process and CCVD in circulating fluidised bed
Authors: Oljaca M. , Sundell S. , Smith P. , Hunt A. , Tellefsen M.
Published: April 2005

Coating of powders is often used to protect particles and to modify surface properties such as lustre, catalytic activity, hardness, permeability, adhesion and conductivity. A fast circulating fluidised bed for combustion chemical vapour deposition (CCVD) and CVD is introduced for the production of particles coated with nanolayers of metal oxides and metals. The CCVD fluidised bed process involves Nanomiser device atomisation and controlled thermal decomposition of low cost metalorganic liquid precursors and nanocoating of particles with thin films or with nanoparticulates while suspended in a turbulent fluidised bed. This paper describes the production of mica and glass spheres uniformly covered with metal oxide (TiO2, Cr2O3) and metal (Ag) films. The coated powder morphology, surface composition and optical properties were characterised by electron and optical microscopy and elemental analysis.
Repressible transgenic model of NRAS oncogene–driven mast cell disease in the mouse
Authors: Wiesner Stephen M. , Jones Jamie M. , Hasz Diane E. , Largaespada David A.
Published: April 2005

To create a model in which to study the effects of RAS dysregulation in hematopoietic disease, we developed separate founder lines of transgenic mice, with the tetracycline transactivator (tTA) driven by the Vav hematopoietic promoter in one line and NRASV12 driven by the tetracycline responsive element (TRE2) in the other. When these lines are crossed, doubly transgenic animals uniformly develop a disease similar to human aggressive systemic mastocytosis (ASM) or mast cell leukemia (MCL) when they are between 2 and 4 months of age. Disease is characterized by tissue infiltrates of large, well-differentiated mast cells in the spleen, liver, skin, lung, and thymus. Analysis of bone sections shows small to large foci of similarly well-differentiated mast cells. Results also show that transgene expression and diseases are repressible through the administration of doxycycline in the drinking water of affected animals, indicating that NRASV12 expression is required to initiate and maintain disease in doubly transgenic mice. Our inducible system of transgenes, developed as a model of mutant NRASV12 oncogene–driven myeloid disease, will be useful for studying the role of RAS dysregulation in hematopoietic disease in general and in discrete human diseases, specifically ASM and MCL.
Hematopoietic differentiation of human embryonic stem cells progresses through sequential hematoendothelial, primitive, and definitive stages resembling human yolk sac development
Authors: Zambidis Elias T. , Peault Bruno , Park Tea Soon , Bunz Fred , Civin Curt I.
Published: April 2005

We elucidate the cellular and molecular kinetics of the stepwise differentiation of human embryonic stem cells (hESCs) to primitive and definitive erythromyelopoiesis from human embryoid bodies (hEBs) in serum-free clonogenic assays. Hematopoiesis initiates from CD45 hEB cells with emergence of semiadherent mesodermal-hematoendothelial (MHE) colonies that can generate endothelium and form organized, yolk sac–like structures that secondarily generate multipotent primitive hematopoietic stem progenitor cells (HSPCs), erythroblasts, and CD13+CD45+ macrophages. A first wave of hematopoiesis follows MHE colony emergence and is predominated by primitive erythropoiesis characterized by a brilliant red hemoglobinization, CD71/CD325a (glycophorin A) expression, and exclusively embryonic/fetal hemoglobin expression. A second wave of definitive-type erythroid burst-forming units (BFU-e's), erythroid colony-forming units (CFU-e's), granulocyte-macrophage colony-forming cells (GM-CFCs), and multilineage CFCs follows next from hEB progenitors. These stages of hematopoiesis proceed spontaneously from hEB-derived cells without requirement for supplemental growth factors during hEB differentiation. Gene expression analysis of differentiating hEBs revealed that initiation of hematopoiesis correlated with increased levels of SCL/TAL1, GATA1, GATA2, CD34, CD31, and the homeobox gene-regulating factor CDX4 These data indicate that hematopoietic differentiation of hESCs models the earliest events of embryonic and definitive hematopoiesis in a manner resembling human yolk sac development, thus providing a valuable tool for dissecting the earliest events in human HSPC genesis.
Microcytic anemia, erythropoietic protoporphyria, and neurodegeneration in mice with targeted deletion of iron-regulatory protein 2
Authors: Cooperman Sharon S. , Meyron-Holtz Esther G. , Olivierre-Wilson Hayden , Ghosh Manik C. , McConnell Joseph P. , Rouault Tracey A.
Published: April 2005

Iron-regulatory proteins (IRPs) 1 and 2 posttranscriptionally regulate expression of transferrin receptor (TfR), ferritin, and other iron metabolism proteins. Mice with targeted deletion of IRP2 overexpress ferritin and express abnormally low TfR levels in multiple tissues. Despite this misregulation, there are no apparent pathologic consequences in tissues such as the liver and kidney. However, in the central nervous system, evidence of abnormal iron metabolism in IRP2-/- mice precedes the development of adult-onset progressive neurodegeneration, characterized by widespread axonal degeneration and neuronal loss. Here, we report that ablation of IRP2 results in iron-limited erythropoiesis. TfR expression in erythroid precursors of IRP2-/- mice is reduced, and bone marrow iron stores are absent, even though transferrin saturation levels are normal. Marked overexpression of 5-aminolevulinic acid synthase 2 (Alas2) results from loss of IRP-dependent translational repression, and markedly increased levels of free protoporphyrin IX and zinc protoporphyrin are generated in IRP2-/- erythroid cells. IRP2-/- mice represent a new paradigm of genetic microcytic anemia. We postulate that IRP2 mutations or deletions may be a cause of refractory microcytic anemia and bone marrow iron depletion in patients with normal transferrin saturations, elevated serum ferritins, elevated red cell protoporphyrin IX levels, and adult-onset neurodegeneration.
IL-6 blocks a discrete early step in lymphopoiesis
Authors: Maeda Kazuhiko , Baba Yoshihiro , Nagai Yoshinori , Miyazaki Kozo , Malykhin Alexander , Nakamura Koji , Kincade Paul W. , Sakaguchi Nobuo , Coggeshall K. Mark
Published: April 2005

Animals lacking Src homology 2 domain-containing inositol 5-phosphatase (SHIP) display a reduction in lymphopoiesis and a corresponding enhancement of myelopoiesis. These effects are mediated at least in part by elevated levels of interleukin 6 (IL-6). Here, we show the lymphopoiesis block in SHIP–/– mice is due to suppression of the lymphoid lineage choice by uncommitted progenitors. The suppression can be reproduced in vitro with recombinant IL-6, and IL-6 acts directly on hematopoietic progenitors. The block is partially overcome in SHIP–/– IL-6–/– double-deficient animals. IL-6 does not suppress but actually enhances proliferation of lymphoid-committed progenitors, indicating the IL-6 target cells are hematopoietic stem cells or multipotent progenitors. The findings suggest a mechanism for the lymphopenia that accompanies proinflammatory diseases.
Inhibitors of mitogen-activated protein kinases differentially regulate costimulated T cell cytokine production and mouse airway eosinophilia
Authors: Chialda Ligia , Zhang Meixia , Brune Kay , Pahl Andreas
Published: April 2005

Background

T cells play a dominant role in the pathogenesis of asthma. Costimulation of T cells is necessary to fully activate them. An inducible costimulator (ICOS) of T cells is predominantly expressed on Th2 cells. Therefore, interference of signaling pathways precipitated by ICOS may present new therapeutic options for Th2 dominated diseases such as asthma. However, these signaling pathways are poorly characterized in vitro and in vivo.

Methods

Human primary CD4+ T cells from blood were activated by beads with defined combinations of surface receptor stimulating antibodies and costimulatory receptor ligands. Real-time RT-PCR was used for measuring the production of cytokines from activated T cells. Activation of mitogen activated protein kinase (MAPK) signaling pathways leading to cytokine synthesis were investigated by western blot analysis and by specific inhibitors. The effect of inhibitors in vivo was tested in a murine asthma model of late phase eosinophilia. Lung inflammation was assessed by differential cell count of the bronchoalveolar lavage, determination of serum IgE and lung histology.

Results

We showed in vitro that ICOS and CD28 are stimulatory members of an expanding family of co-receptors, whereas PD1 ligands failed to co-stimulate T cells. ICOS and CD28 activated different MAPK signaling cascades necessary for cytokine activation. By means of specific inhibitors we showed that p38 and ERK act downstream of CD28 and that ERK and JNK act downstream of ICOS leading to the induction of various T cell derived cytokines. Using a murine asthma model of late phase eosinophilia, we demonstrated that the ERK inhibitor U0126 and the JNK inhibitor SP600125 inhibited lung inflammation in vivo. This inhibition correlated with the inhibition of Th2 cytokines in the BAL fluid. Despite acting on different signaling cascades, we could not detect synergistic action of any combination of MAPK inhibitors. In contrast, we found that the p38 inhibitor SB203580 antagonizes the action of the ERK inhibitor U0126 in vitro and in vivo.

Conclusion

These results demonstrate that the MAPKs ERK and JNK may be suitable targets for anti-inflammatory therapy of asthma, whereas inhibition of p38 seems to be an unlikely target.
Improved profile HMM performance by assessment of critical algorithmic features in SAM and HMMER
Authors: Wistrand Markus , Sonnhammer Erik LL
Published: April 2005

Background

Profile hidden Markov model (HMM) techniques are among the most powerful methods for protein homology detection. Yet, the critical features for successful modelling are not fully known. In the present work we approached this by using two of the most popular HMM packages: SAM and HMMER. The programs' abilities to build models and score sequences were compared on a SCOP/Pfam based test set. The comparison was done separately for local and global HMM scoring.

Results

Using default settings, SAM was overall more sensitive. SAM's model estimation was superior, while HMMER's model scoring was more accurate. Critical features for model building were then analysed by comparing the two packages' algorithmic choices and parameters. The weighting between prior probabilities and multiple alignment counts held the primary explanation why SAM's model building was superior. Our analysis suggests that HMMER gives too much weight to the sequence counts. SAM's emission prior probabilities were also shown to be more sensitive. The relative sequence weighting schemes are different in the two packages but performed equivalently.

Conclusion

SAM model estimation was more sensitive, while HMMER model scoring was more accurate. By combining the best algorithmic features from both packages the accuracy was substantially improved compared to their default performance.
Transcriptome analysis in primary neural stem cells using a tag cDNA amplification method
Authors: Sievertzon Maria , Wirta Valtteri , Mercer Alex , Meletis Konstantinos , Erlandsson Rikard , Wikström Lilian , Frisén Jonas , Lundeberg Joakim
Published: April 2005

Background

Neural stem cells (NSCs) can be isolated from the adult mammalian brain and expanded in culture, in the form of cellular aggregates called neurospheres. Neurospheres provide anin vitromodel for studying NSC behaviour and give information on the factors and mechanisms that govern their proliferation and differentiation. They are also a promising source for cell replacement therapies of the central nervous system. Neurospheres are complex structures consisting of several cell types of varying degrees of differentiation. One way of characterising neurospheres is to analyse their gene expression profiles. The value of such studies is however uncertain since they are heterogeneous structures and different populations of neurospheres may vary significantly in their gene expression.

Results

To address this issue, we have used cDNA microarrays and a recently reported tag cDNA amplification method to analyse the gene expression profiles of neurospheres originating from separate isolations of the lateral ventricle wall of adult mice and passaged to varying degrees. Separate isolations as well as consecutive passages yield a high variability in gene expression while parallel cultures yield the lowest variability.

Conclusions

We demonstrate a low technical amplification variability using the employed amplification strategy and conclude that neurospheres from the same isolation and passage are sufficiently similar to be used for comparative gene expression analysis.
Can pulsed ultrasound increase tissue damage during ischemia? A study of the effects of ultrasound on infarcted and non-infarcted myocardium in anesthetized pigs
Authors: Olivecrona Göran K , Härdig Bjarne Madsen , Roijer Anders , Block Mattias , Grins Edgars , Persson Hans W , Johansson Leif , Olsson Bertil
Published: April 2005

Background

The same mechanisms by which ultrasound enhances thrombolysis are described in connection with non-beneficial effects of ultrasound. The present safety study was therefore designed to explore effects of beneficial ultrasound characteristics on the infarcted and non-infarcted myocardium.

Methods

In an open chest porcine model (n = 17), myocardial infarction was induced by ligating a coronary diagonal branch. Pulsed ultrasound of frequency 1 MHz and intensity 0.1 W/cm2 (ISATA) was applied during one hour to both infarcted and non-infarcted myocardial tissue. These ultrasound characteristics are similar to those used in studies of ultrasound enhanced thrombolysis. Using blinded assessment technique, myocardial damage was rated according to histopathological criteria.

Results

Infarcted myocardium exhibited a significant increase in damage score compared to non-infarcted myocardium: 6.2 ± 2.0 vs. 4.3 ± 1.5 (mean ± standard deviation), (p = 0.004). In the infarcted myocardium, ultrasound exposure yielded a further significant increase of damage scores: 8.1 ± 1.7 vs. 6.2 ± 2.0 (p = 0.027).

Conclusion

Our results suggest an instantaneous additive effect on the ischemic damage in myocardial tissue when exposed to ultrasound of stated characteristics. The ultimate damage degree remains to be clarified.