bluuebunny/crossref_metadata_2025 huggingface dataset:
Precipitation and hardening mechanisms of an ion nitrided H-12 tool steel
Authors: Albarran J.L. , Campillo B. , Constantino M.E.
Published: May 2005

In order to investigate the combined effects of tempering and ion nitriding on H-12 tool steel, specimens were tempered at 550 and 580°C and subsequently ion nitrided at 500°C for various times. The effect of the specimen treatments was analysed by microhardness testing, fractography, X-ray diffractometry, and transmission electron microscopy (TEM). A linear increase in the surface microhardness was observed up to 27 ks, however at longer times the surface microhardness decreased. The hardness increase is related to precipitation of iron nitrides, chromium carbonitrides, and tungsten carbides. The maximum hardness reached correlated with the maximum numbers of chromium carbonitrides and tungsten carbides, as demonstrated by the X-ray diffraction analysis. The TEM study shows that the increase is mainly a result of the coherent precipitation of W2 C in an Fe4 N matrix. Also, TEM observations reveal that in specimens nitrided for shorter times (9 and 18 ks) martensite is transformed into the nitride Fe16 N2 (α″). The microhardness decrease observed in specimens treated for longer times is caused by loss of toughness in the grain boundaries.
Silane based chromate replacements for corrosion control, paint adhesion, and rubber bonding
Authors: van Ooij W.J. , Zhu D.Q. , Prasad G. , Jayaseelan S. , Fu Y. , Teredesai N.
Published: May 2005

An overview is given of the use of silanes for corrosion control of metals and bonding of silane treated metals to paint systems and rubber compounds. Examples are given of corrosion protection of cold rolled steel, galvanised steel, aluminium, and magnesium, both painted and unpainted. Emphasis in this work has been on the use of bis-silanes rather than the conventional mono-silanes. It is shown that mixtures of a bis-amino and a bis-polysulphur silane work with a wide range of metals and paint systems. A model is described which is largely based on electrochemical impedance spectroscopy (EIS) measurements.
Diffraction techniques for study of ceramic thermal barrier coatings
Authors: Leoni M. , Scardi P.
Published: May 2005

Diffraction techniques are particularly suited for the study of the structural and mechanical properties of ceramic thermal barrier coatings (TBCs) for applications in engine components. Both X-ray (lab and synchrotron radiation) and neutron diffraction permit a non-destructive determination of phase content and several interesting related properties. Besides identification and quantitative phase analysis, detailed information can also be obtained on the residual strain field, both on the surface of the coating and through entire coated components, and on possible texture of deposited layers. This type of analysis is especially important for the design and production of TBCs, as well as for determination of the useful life of coated components. Some of the methodologies described in this work can be applied on a routine basis for quality control at the industrial level.
Techniques for improved surface integrity of electrodischarge machined ceramic composites
Authors: deng J.X. , Lee T.C.
Published: May 2005

Good surface integrity is frequently required of structural ceramic components, since the lifetime of a ceramic component is, in most cases, determined by its surface features. In this study, two mechanical surface treatments, i.e. ultrasonic and abrasive blasting surface finishing, have been introduced to the surface of electrodischarge machined ceramic composites to improve their surface integrity. The surface roughness, hardness, and topography of the ceramic composites were examined after electrodischarge machining (EDM) and surface treatment. The effect of surface integrity on the strength and its distribution was investigated. Results show that ultrasonic and abrasive blasting surface finishing can produce an improvement in both flexural strength and Weibull modulus, and are two effective procedures to improve the surface integrity of the EDM ceramic composites.
Effect of heat treatment on properties of nickel hard surface alloy deposited by hvof
Authors: Rodriguez M. , Staia M. , Gil L. , Arenas F. , Scagni A.
Published: May 2005

There are numerous industrial applications in which materials are subject simultaneously to high temperature, oxidation, corrosion, and wear leading to accelerated degradation. Some specific industries where these phenomena have been detected are: chemical, waste incineration, power generation, and paper/pulp with typical applications including boilers, cyclones, heat exchangers, and tubing. Previous studies have established some material compositions and microstructures that can resist these environments. In the search for cost effective industrial solutions, surface coating via thermal spraying becomes attractive. However, not all coatings have been successful in the past owing to adhesion problems, porosity, or unsatisfactory resistance to corrosion and erosion. Spray and fused coatings like nickel hard surface alloys are ideally suited for the elevated temperature environment. The present paper studies the effect of heat treatment, carried out using an oxyacetylene flame, on the microstructure, microhardness, erosion wear, and adhesion resistance of a NiCrBSiW alloy, commercially known as Colmonoy 88, deposited on a plain carbon steel using both wire and powder fed high velocity oxyfuel (HVOF) spray processes.
Quality and reliability in diamond deposition using CVD
Authors: Ali N. , Ahmed W. , Fan Q.H.
Published: May 2005

In the manufacturing industry, quality and reliability have become very important issues for both consumer and industrial products. These issues need be addressed in order for companies to remain competitive within the global marketplace. By way of illustration, a process known as chemical vapour deposition (CVD) is considered in this paper. This process is now widely used in industry to deposit a number of thin films for a diverse range of applications such as microelectronics, biomedical components, cutting tools, ophthalmic lenses, and decorative products. Polycrystalline diamond films have been selected to illustrate the importance of factors effecting the quality and reliability of films deposited. The effects of process parameters such as temperature, substrate properties, cleanliness, methane gas concentration, and adhesion are described. In addition, in order to achieve the maximum benefit from film quality and reliability, a ‘systems approach’ is discussed taking into consideration substrate pretreatments, deposition stages, and post-deposition treatments.
Performance of PVD hard ceramic coatings on HSS cutting tools during machining of free cutting steels
Authors: Malik H. , Bradley R. , Mills B.
Published: May 2005

The effect of a hard ceramic physical vapour deposited coating on high speed steel (HSS) cutting tools on the machining behaviour of free cutting steels has been studied. TiN, TiCN, and CrN coatings were applied to M2 high speed steels and studies were made of MnS layer formation on the rake face of the cutting tool after a continuous short cutting time. The compositions of the deposited layers were assessed by X-ray analyses of coated and uncoated M2 high speed steel tools. MnS layers have been observed to form within certain cutting conditions depending on the type of coating. Such tribological layers across the tool/chip interface improve machining performance, which has been confirmed by measurements of cutting force.
Direct current iron plating without pre-etching and performance of iron deposit
Authors: Kang Y.P. , Chen L.J. , Sun T.L. , Hong H.
Published: May 2005

A new direct current iron plating technique without pre-etching was investigated. The cathodic polarisation curves of the iron plating solution were measured and a theoretical analysis of these curves was carried out. The influence of current density on the deposition rate and microhardness of the iron deposit was investigated. The effects of heat treatment on the microhardness of the deposit were also determined.
Effect of rf plasma nitriding power density on microhardness, structure, and magnetic properties of 304 austenite stainless steel
Authors: El-Hossary F.M.
Published: May 2005

Structural phases, microhardness, and magnetic properties of nitrided 304 austenite stainless steel prepared using different rf plasma power densities ranging from 78·5 to 138 W cm-2 torr-1 have been investigated. The results of X-ray diffraction revealed that the structural phases of the nitrided layers are strongly dependent on the nitriding plasma power density. Fe2–3 N, Fe4 N, CrN, and α ferrite are the main phases formed in the treated layers which can be easily identified. The hysteresis loops of the samples were measured using a vibrating sample magnetometer, from which the saturation magnetisation Ms, remnant magnetisation Br, coercive field Hc, and magnetic susceptibility χ, were evaluated. The highest values of Ms, Br, Hc, and χ were obtained when the samples were nitrided at around 106 W cm-2 torr-1. This behaviour can be explained in terms of the high precipitation of CrN and Fe4 N at this nitriding plasma power density.
Wear resistance of electroless deposited Ni–P and Ni–P/SiC composite coatings on low alloy cast iron
Authors: Wu Y.C. , Li G.H. , Zhang L.
Published: May 2005

Nickel–phosphorus alloy and Ni–P/SiC composite coatings were prepared on low alloy cast iron surfaces using the electroless deposition method. The wear properties of both coatings were evaluated and compared with those of cast iron, phosphate coating, and chromium plating. The results indicate that the electroless deposited Ni–7·0 wt-%P coating is a supersaturated solid solution, and the Ni3 P phase can be precipitated when heat treated at a temperature of 350°C, which increases the hardness. However, when the heat treatment temperature is higher than 400°C the hardness decreases rapidly, but the wear volume still decreases continuously. Not only is the hardness of the Ni–P/SiC composite coating high, but its wear resistance is better than that of the Ni–P coating, chromium plating, cast iron substrate, and the phosphatising coating. Under the given experimental conditions, the wear volume of the Ni–P/SiC composite coating is the lowest.
Improvement of corrosion resistance of unbalanced magnetron deposited Nb coatings by high energy metal ion pretreatment: First Prize
Authors: Paritong H.
Published: May 2005

The quality of corrosion resistant thin films depends on a number of factors, in particular the microstructure and degree of porosity of the coating. The micro structure of thin films deposited by the physical vapour deposition technique of unbalanced magnetron sputtering is strongly influenced by the deposition temperature and by the melting point of the condensed material. It becomes increasingly difficult to produce dense coatings at low deposition temperatures for metals such as Nb with a melting point TM = 2500°C. The present study investigates the influence of ion etching pretreatment and of deposition temperature on the corrosion resistance of Nb thin films deposited by the combined cathodic arc–magnetron sputter deposition technique. Metal ion etching using Cr ions and Nb ions is compared to inert Ar ion etching. The coatings, deposited on 304 stainless steel substrates, are tested by potentiodynamic and potentiostatic polarisation measurements in a 3%NaCl solution and compared to electroplated chromium and electroless nickel films.
Surface engineering by powder coinjection moulding
Authors: Hanson S.
Published: May 2005

Intricately shaped surface engineered components have been produced using the technique of powder coinjection moulding. Powder coinjection moulding is the combi nation of two processing methods, polymer sandwich moulding and powder injection moulding, and has been used to produce metal or ceramic surface engineered components using several model material systems. Surface engineering was achieved by the addition of rigid non-sinterable particles or alloying particles. Modelling of the coinjection moulding process using a commercial finite element computer program, C-Mold, has demonstrated the ability to predict the skin thickness and distribution as a function of processing conditions and material properties. The ability to engineer surfaces as part of the powder injection moulding cycle provides a further incentive for the additional exploitation of the powder injection moulding process.
Evaluation of diamond film on cemented carbide substrate
Authors: Zhou K.S. , Dai M.J. , Kuang T.C. , Wang D.Z. , Liu Z.Y.
Published: May 2005

Diamond films with a thickness of 8 μm were deposited using plasma jet chemical vapour deposition on to cemented carbide substrates that had been chemically etched and bombarded by Ar–H2 plasma before synthesis. The interfaces and cross-sections of the diamond films and cemented carbide substrates were analysed by SEM, TEM, and Fourier transform Raman spectroscopy. Under the deposition conditions used, the typical structure of the diamond film and cemented carbide substrate was diamond film/thin graphite layer/fine WC particle layer/residual chemical etch layer/cemented carbide substrate. Cobalt, which diffused from the substrate to the interface, caused the formation of a graphite layer which was several hundreds of nanometres thick. However in some regions diamond particles grew directly on to the cemented carbide.
Ion implantation technique as research tool for improving oxidation behaviour of tial based intermetallic alloys
Authors: Haanappel V.A.C. , Stroosnijder M.F.
Published: May 2005

The effect of various elements added by ion implantation on the isothermal (up to 150 h) and cyclic (up to 1500 h) oxidation behaviour of γ-TiAl based intermetal lic alloys at 800 and 900°C in air has been studied. At 800°C ion implantation of Si, Nb, Ta, W, and Al showed a large beneficial effect on the oxidation behaviour of Ti–48Al–2Cr. A minor effect was found for Ti, Mo, Y, Mn, Pt, Rh, and Cr. More important was the oxidation of specimens implanted with Si or Nb, which revealed similar results to those for the intermetallic materials alloyed with these elements, i.e. Ti–47Al–2Cr–0·2Si and Ti–48Al–2Cr–2Nb. From this point of view it was concluded that the ion implantation technique can be employed as a ‘screening’ test for evaluating the effect of possible alloying additions. As a followup this technique was used as a research tool to study the effect of Nb, Pt, Rh, Si, Ta, and W on the oxidation behaviour of two types of Nb bearing TiAl based intermetallic alloys, i.e. Ti–48Al–2Cr–2Nb and Ti–48Al–2Mn–2Nb, at 900°C in air. In this case, no significant effect of the implanted elements on the isothermal and cyclic oxidation behaviour was found.
Nanoceramic caotings produced by laser treatment
Authors: de Hosson J.T.M. , Teeuw D.H.J.
Published: May 2005

Sol–gel derived thin nanoceramic layers of TiO2, SiO2, and Al2O3 are studied using scanning electron microscopy to reveal the microstructure and morphologies of the layers. The low voltage scanning electron microscope with a field emission gun is equipped with a specially designed lens. The specimen is placed where the magnetic field is largest and a maximum resolving power of 1·5 nm at 3 kV accelerating voltage could be attained. The melt spun layers were treated by either furnace or laser curing, which appeared to dictate the final morphologies of the layers to a large extent. Grain growth was present in furnace cured and laser cured layers and the activation energy for grain growth of these layers was determined. Homogeneous dense layers were obtained if the parameters in the curing process were selected appropriately. If the parameters were chosen incorrectly, severely debonded layers were obtained. Preheating the layers resulted in less blister formation. The mechanisms which may cause the layers to fail are examined in more detail.
Formation of reaction layers in steel machining: Impact on surface treatment processes
Authors: Haase B. , Stiles M. , Haasner T. , Walter A.
Published: May 2005

During production and machining, metal parts come into contact with cooling lubricants which protect the tool from wear. Cooling lubricants are responsible for heat and swarf removal as well as for friction reduction. For this reason they contain additives which form reaction layers not only at the tool surface, but also on the surface of the workpiece. Residues of cooling lubricants are thought to cause problems in surface treatment processes if they are not removed by efficient cleaning/degreasing. This is hardly practicable as long as it is unknown what contamination (and how much of it) has to be removed to obtain a desired physicochemical surface condition. Thus it is necessary to identify the composition of reaction layers and to determine critical surface concentrations which must not be exceeded if the surface treatment process is to function properly. Reaction layers have been prepared on steel by milling using different cutting oils, consisting of a mineral or synthetic base oil and additives in different concentrations. X-ray photoelectron spectroscopy was used to analyse surface composition after milling, and electrochemical measurements were carried out to establish the condition of the metal surfaces. Gas nitriding was used as a model surface treatment process to examine the impact of these reaction layers on the reactivity of a steel surface.
Structural and electrochemical characterisation of metal doped diamondlike carbon films
Authors: Koduri P. , Sunkara M.K. , Dickey E.C. , Frazier C. , Babu S.V.
Published: May 2005

The structural and electrochemical characteristics of metal doped diamondlike carbon films with conductivities higher that 5 Ω-1 cm-1 are investigated using TEM and electrochemical characterisation techniques. Cyclic voltammetry of hafnium doped diamondlike carbon films in acidic solutions shows that these films are electrochemically stable compared with pure hafnium metal surfaces. Highly doped Cr–DLC films show the presence of metal dopant in the form of nanoclusters while moderately doped films show randomly dispersed chromium metal dopant. In addition, these Cr–DLC films with nanoclusters of metal dopant show two orders of magnitude enhancement in electrochemical activity with gas evolution in acidic environments compared with the Cr–DLC films with randomly dispersed metal dopant. This difference is attributed to possible electrocatalytic activity of nanoclusters.
Electropolishing of Zinalco and characterisation of resulting surface
Authors: Guerrero R. , Cota L. , Machorro R.
Published: May 2005

The present paper studies electropolishing conditions on a Zn–22l–2Cu, multiphase alloy called Zinalco. The aim of this work is to obtain reproducible surfaces free of mechanical damage to be used in subsequent corrosion and thin film growing studies. Polarisation curves show that temperature and current density are the most relevant parameters in order to obtain good quality polished surfaces. The specimen morphology was observed by scanning electron microscopy, showing regions with different contrasts and with no pits, nor preferentially etched zones. Energy dispersive X-ray spectroscopy reveals differences in chemical composition associated with regions of different contrast. The surface chemical composition was obtained using X-ray photoelectron spectroscopy and Auger electron spectroscopy. Results indicate a surface formed by Zn and Al oxides with Al enrichment. Finally, surface profile measurements were carried out in order to evaluate the electropolishing conditions.
New possibilities for controlling gas nitriding process by simulation of growth kinetics of nitride layers
Authors: Maldzinski L. , Liliental W. , Tymowski G. , Tacikowski J.
Published: May 2005

This paper presents results of computerised simulations of the gas nitriding process, demonstrating the influence of the nitriding potential of NH3–H2 atmosphere on the composition and growth kinetics of γ′ and ɛ nitride layers on pure iron. For the simulation, the recently developed KN–T phase diagram and growth kinetics models for both phases were utilised, as well as the latest results of experimental research. Simulation results indicate optimum possibilities of process control for the formation of layers of predictable phase composition, thickness of particular zones, and surface nitrogen concentrations. Also included are data on growth kinetics of the nitride layer (ɛ/γ′ and α zones) on alloy steels. The role of nitride forming and other alloying elements in process kinetics is discussed.
Nickel diffusion treatment of Timetal 550 titanium alloy
Authors: Kwietniewski C. , Dong H. , Bloyce A. , Bell T.
Published: May 2005

A series of nickel diffusion treatments have been carried out on Timetal 550 titanium alloy at temperatures ranging from 650 to 900°C in order to achieve deep case hardening. Systematic characterisation of the nickel diffusion treated surface layers was performed using GDS, XRD, EDS, SEM, and optical microscopy. Microhardness and compositional profiles have been carried out in order to reveal the hardening effect and the nickel penetration. The sliding wear resistance against hardened 709M40 steel was evaluated using an Amsler wear tester. The results have shown that by choosing proper treatment parameters, different combinations of intermetallics from the system Ti–Ni can be formed in a selective manner. In addition, with specific conditions it is possible to form diffusion zones without intermetallics on the surface. Finally, a significant improvement in the sliding wear resistance was observed for treated specimens under unlubricated and lightly loaded conditions.
Manganese based conversion treatment
Authors: Danilidis I. , Sykes J.M. , Hunter J.A. , Scamans G.M.
Published: May 2005

Environmental concerns relating to chromate containing conversion treatments employed for the protection of aluminium alloys from corrosion have led to a search for their replacement. In this study, an alternative manganese based treatment has been examined. Its properties have been examined using electrochemical, electron microscopical, and spectroscopical techniques. Promising results have been obtained and further research is being carried out to provide a better understanding of the mechanism responsible for its good performance.
Titanium based conversion coatings on aluminium alloy 3003
Authors: Smit M.A. , Sykes J.M. , Hunter J.A. , Sharman J.D.B. , Scamans G.M.
Published: May 2005

The performance and characteristics of a no rinse, titanium based conversion coating on an aluminium alloy have been studied using electrochemical techniques and transmission electron microscopy. Coatings were prepared from an aqueous H2 TiF6 solution, spin coated onto aluminium alloy 3003. The electrochemical behaviour evolves with time during exposure to 0·5% and 3·5%NaCl. Polarisation curves and impedance data correspond well and indicate that the anodic inhibition and polarisation resistance increase dramatically with time. However, no cathodic inhibition is found. Metastable pitting was observed at potentials below the pitting potential. TEM micrographs taken from cross-sections of coated material show that the coating thickness is of the order of 30 nm and that with immersion a mixed metal oxide layer appears at the substrate/coating interface.
Influence of post-heat treatment and complexing agents on hardness of Ni–Cr alloy coatings
Authors: Bahrololoom M.E. , Hoveidaei A.
Published: May 2005

The presence of complexing agents in the electroplating bath and post-heat treatment are two factors which influence the structure of electroplated alloy coatings. Any change in structure is accompanied by changes in coating physical and mechanical properties such as hardness. The aim of this study was to investigate the effects of complexing agents present in the electroplating bath and post-heat treatment on the hardness of electroplated Ni–Cr coatings obtained from two different baths, one containing sodium citrate as its complexing agent and the other containing dimethyl- formamide. The hardness of coatings obtained from both types of electroplating bath increased with coating chromium content. Coatings obtained from the sodium citrate bath were generally harder than those obtained from the bath containing dimethylformamide. Alloy coatings with 18 and 35%Cr were selected for this study. The hardness did not decrease after heat treatment up to about 300°C, but further increase in annealing temperature caused a sharp decrease in the hardness of deposits. This decrease in coating hardness with increase in the annealing post-heattreatment temperature was observed for all coatings.
Phase and microstructural study of surface layers produced by plasma immersion ion implantation of stainless steel X6CrNiTi1810
Authors: Blawert C. , Mordike B.L. , Jirásková Y. , Schneeweiss O.
Published: May 2005

A complex study of austenitic stainless steel X6CrNiTi1810 modified by nitrogen plasma immersion ion implantation (PI3) at 300 and 400°C is presented. To obtain detailed information on the structure and phase compositions, conversion electron Mössbauer spectroscopy, XRD, TEM, and Rutherford back scattering spectroscopy are applied. Depending on the treatment temperature a mixture of several phases is observed by Mössbauer phase analysis and confirmed by TEM. The dominant component in specimens treated at 300°C is a paramagnetic oversaturated austenitic phase. A higher implantation temperature (400°C) evokes more pronounced diffusion of nitrogen into the specimen volume, causing a decrease of nitrogen concentration but an increase of stress in the surface layer. This influences the defect density and results in a change of the expanded austenitic phase. Nitride formation is also different depending on the temperature. Furthermore, a texturing of the grains is observed after the PI3 treatment at both temperatures.
Plasma ferritic nitrocarburising of carbon and low alloy 0·4%c steels in N2–H2 atmospheres with CO2 gas additions
Authors: Howse H.J. , Pistorius P.G.H.
Published: May 2005

Plasma ferritic nitrocarburising of carbon and low alloy 0·4%C steels was carried out at 570°C in a N2–H2 atmosphere containing CO2 gas additions. The influence of the atmosphere composition, the duration of treatment, and the composition and microstructure of the steels on the phase composition of the compound layer was investigated. The formation of a monophase ɛ compound layer was not possible with the parameters used in this study. The phase composition of the compound layer was found to be very dependent on the amount of CO2 in the process gas. A difference in the plasma nitrocarburising behaviour of the two low alloy steel grades was observed, and the formation of some austenite in the diffusion zone of one of the steels, at the interface with the compound layer, is proposed to explain this observation.
Wear and corrosion resistance of PTA weld surfaced Ni and CO based alloy layers
Authors:   Kim H.-J., Kim Y.J.
Published: May 2005

Microstructural development in the hardfacing alloys NiCrBSi and Stellite 6 resulting from the commercially available ‘open arc’ and ‘spray and fuse’ coating techniques was compared with that resulting from the plasma transferred arc (PTA) weld surfacing process. Denser eutectic structures were observed in the case of PTA weld surfaced layers of Stellite 6 in comparison with the open arc weld surfacing process. The shapes of both carbides and borides in the 16C alloy (NiCrBSi type) coated by PTA processing were observed to have coarse morphology, while the spray and fuse layers showed needlelike morphology with finer distribution. The possible thermal history during each coating process is discussed. Based on microstructural observation, the hardness, wear resistance, and corrosion behaviours are reported. As expected, the alloy properties are directly related to the microstructural constituents.
Splenic marginal zone lymphoma: proposal of new diagnostic and prognostic markers identified after tissue and cDNA microarray analysis
Authors: Ruiz-Ballesteros Elena , Mollejo Manuela , Rodriguez Antonia , Camacho Francisca I. , Algara Patrocinio , Martinez Nerea , Pollán Marina , Sanchez-Aguilera Abel , Menarguez Javier , Campo Elias , Martinez Pedro , Mateo Marisol , Piris Miguel A.
Published: May 2005

Splenic marginal zone lymphoma (SMZL) is a newly recognized lymphoma type whose precise molecular pathogenesis is still essentially unknown. This hampers differential diagnosis with other small B-cell malignancies. With the aim of characterizing this tumor more comprehensively, and of identifying new diagnostic and prognostic markers, we performed cDNA microarray expression profiling and tissue microarray (TMA) immunohistochemical studies in a relatively large series of 44 SMZLs. The results were related to immunoglobulin heavy chain variable region (IgVH) mutational status and clinical outcome. SMZLs display a largely homogenous signature, implying the existence of a single molecular entity. Of the genes deregulated in SMZLs, special mention may be made of the genes involved in B-cell receptor (BCR) signaling, tumor necrosis factor (TNF) signaling and nuclear factor-κB (NF-κB) activation, such as SYK, BTK, BIRC3, TRAF3, and LTB. Other genes observed were SELL and LPXN, which were highly expressed in spleen, and lymphoma oncogenes, such as ARHH and TCL1. In contrast, the genes CAV1, CAV2, and GNG11 located in 7q31, a commonly deleted area, were down-regulated in the entire series. A comparison with the genes comprising the signature of other small B-cell lymphomas identified 3 genes whose expression distinguishes SMZL, namely ILF1, SENATAXIN, and CD40. Shorter survival was associated with CD38 expression, naive IgVH genes, and the expression of a set of NF-κB pathway genes, including TRAF5, REL, and PKCA. (Blood. 2005;106:1831-1838)
Inhibitors of XIAP sensitize CD40-activated chronic lymphocytic leukemia cells to CD95-mediated apoptosis
Authors: Kater Arnon P. , Dicker Frank , Mangiola Massimo , Welsh Kate , Houghten Richard , Ostresh John , Nefzi Adel , Reed John C. , Pinilla Clemencia , Kipps Thomas J.
Published: May 2005

Patients with chronic lymphocytic leukemia (CLL) treated with adenovirus CD154 (Ad-CD154, CD40 ligand [CD40L]) gene therapy experienced rapid reductions in leukemia cell counts and lymph node size associated with the induced expression of Fas (CD95). However, CLL cells initially resist CD95-mediated apoptosis within the first 3 days after CD40 ligation in vitro. Thereafter, they become sensitive, which is associated with the CD40-induced expression of the proapoptotic protein B-cell leukemia 2 homology 3 (BH3) interacting domain death agonist (Bid). We hypothesized that the initial resistance to CD95-mediated apoptosis may be due to the high-level expression of X-linked inhibitor of apoptosis protein (XIAP) by CLL cells. Consistent with this, CLL cells from patients 1 day after treatment with autologous Ad-CD154-transduced CLL cells became sensitive to CD95-mediated apoptosis following treatment with a novel XIAP inhibitor, 1540-14. Similarly, 1540-14 specifically enhanced CD95-mediated apoptosis of CLL cells following CD40 ligation in vitro. Immunoblot analyses demonstrated that treatment with 1540-14 allowed CD40-stimulated CLL cells to experience high-level activation of caspases-8 and -3 and cleavage of poly(adenosine diphosphate [ADP]-ribose) polymerase following CD95 ligation. This study demonstrates that distal apoptosis regulators contribute to the initial resistance of CD40-activated CLL cells to CD95-mediated apoptosis and suggests that XIAP inhibitors might enhance the effectiveness of immune-based treatment strategies that target CD40, such as CD154 gene therapy. (Blood. 2005;106:1742-1748)
Effect of transcription-factor concentrations on leukemic stem cells
Authors: Rosenbauer Frank , Koschmieder Steffen , Steidl Ulrich , Tenen Daniel G.
Published: May 2005

Increasing evidence suggests that leukemias are sustained by leukemic stem cells. However, the molecular pathways underlying the transformation of normal cells into leukemic stem cells are still poorly understood. The involvement of a small group of key transcription factors into this process was suggested by their frequent mutation or down-regulation in patients with acute myeloid leukemia (AML). Recent findings in mice with hypomorphic transcription-factor genes demonstrated that leukemic stem-cell formation in AML could directly be caused by reduced transcription-factor activity beyond a critical threshold. Most interestingly, those experimental models and the paucity of biallelic null mutations or deletions in transcription-factor genes in patients suggest that AML is generally associated with graded down-regulation rather than complete disruption of transcription factors. Here, we discuss the effects of transcription-factor concentrations on hematopoiesis and leukemia, with a focus on the regulation of transcription-factor gene expression as a major mechanism that alters critical threshold levels during blood development and cancer.
Distinctive and indispensable roles of PU.1 in maintenance of hematopoietic stem cells and their differentiation
Authors: Iwasaki Hiromi , Somoza Chamorro , Shigematsu Hirokazu , Duprez Estelle A. , Iwasaki-Arai Junko , Mizuno Shin-ichi , Arinobu Yojiro , Geary Kristin , Zhang Pu , Dayaram Tajhal , Fenyus Maris L. , Elf Shannon , Chan Susan , Kastner Philippe , Huettner Claudia S. , Murray Richard , Tenen Daniel G. , Akashi Koichi
Published: May 2005

The PU.1 transcription factor is a key regulator of hematopoietic development, but its role at each hematopoietic stage remains unclear. In particular, the expression of PU.1 in hematopoietic stem cells (HSCs) could simply represent “priming” of genes related to downstream myelolymphoid lineages. By using a conditional PU.1 knock-out model, we here show that HSCs express PU.1, and its constitutive expression is necessary for maintenance of the HSC pool in the bone marrow. Bone marrow HSCs disrupted with PU.1 in situ could not maintain hematopoiesis and were outcompeted by normal HSCs. PU.1-deficient HSCs also failed to generate the earliest myeloid and lymphoid progenitors. PU.1 disruption in granulocyte/monocyte-committed progenitors blocked their maturation but not proliferation, resulting in myeloblast colony formation. PU.1 disruption in common lymphoid progenitors, however, did not prevent their B-cell maturation. In vivo disruption of PU.1 in mature B cells by the CD19-Cre locus did not affect B-cell maturation, and PU.1-deficient mature B cells displayed normal proliferation in response to mitogenic signals including the cross-linking of surface immunoglobulin M (IgM). Thus, PU.1 plays indispensable and distinct roles in hematopoietic development through supporting HSC self-renewal as well as commitment and maturation of myeloid and lymphoid lineages.
Negative control of basophil expansion by IRF-2 critical for the regulation of Th1/Th2 balance
Authors: Hida Shigeaki , Tadachi Masumi , Saito Takashi , Taki Shinsuke
Published: May 2005

Although basophils are known to produce interleukin 4 (IL-4), the roles of these cells have been documented only in mice infected with parasites or in the effector phase of allergic inflammations. Here we show that naive mice lacking the transcription factor, interferon regulatory factor 2 (IRF-2), exhibited signal transducer and activator of transcription 6 (Stat6)–independent expansion of basophils in the periphery. IRF-2 appeared to act autonomously in the cells to negatively regulate the expansion of, but not cytokine production by, basophils. Spontaneous Th2 polarization of CD4+ T cells was observed in these mice and the genetic reduction of basophil numbers by mutating the Kit gene abolished such a polarization in vivo. We also found that both basophils and IL-4 derived from them were indeed essential for Th2 development under neutral conditions in vitro. Furthermore, neutralization of IL-3 abolished IL-4 production by basophils during Th1/Th2 differentiation cultures and subsequent Th2 development. These results indicated that basophils acted as a cellular converter to turn the neutral IL-3 into the Th2-inducing IL-4 during the initiation of Th1/Th2 differentiation. Thus, the negative regulatory role of IRF-2 on the basophil population size is critically important for preventing excess Th2 polarization and the Th1/Th2 balance in naive animals.
Comparative genomics of Helicobacter pylori isolates recovered from ulcer disease patients in England
Authors: Kauser Farhana , Hussain M Abid , Ahmed Irshad , Srinivas Sriramula , Devi S Manjulata , Majeed Ahmed A , Rao K Rajender , Khan Aleem A , Sechi Leonardo A , Ahmed Niyaz
Published: May 2005

Background

Genomic diversity of H. pylori from many different human populations is largely unknown. We compared genomes of 65 H. pylori strains from Nottingham, England. Molecular analysis was carried out to identify rearrangements within and outside the cag-pathogenicity-island (cag PAI) and DNA sequence divergence in candidate genes. Phylogenetic analysis was carried out based on various high-resolution genotyping techniques.

Results

Analyses of virulence genes (cag T, cag E, cag A, vac A, ice A, oip A and bab B) revealed that H. pylori strains from England are genetically distinct from strains obtained from other countries. The toxigenic vac A s1m1 genotype was found to be less common and the plasticity region cluster was found to be disrupted in all the isolates. English isolates showed a predominance of ice A1 alleles and a functional proinflammatory oip A gene. The English H. pylori gene pool revealed several Asian/oriental features. This included the predominance of cag A – glr (cag A right junction) motif types III and II (up to 42%), presence of vac A m1c alleles and phylogenetic affinity towards East Asian / Amerindian gene pools based on fluorescent amplified fragment length polymorphism (FAFLP) analysis and glm M sequence analysis.

Conclusion

Overall, our results demonstrated genetic affinities of H. pylori in England with both European and the Asian gene pools and some distinctive genetic features of virulence genes that may have evolved in this important European population.
Surface TRAIL decoy receptor-4 expression is correlated with TRAIL resistance in MCF7 breast cancer cells
Authors: Sanlioglu Ahter D , Dirice Ercument , Aydin Cigdem , Erin Nuray , Koksoy Sadi , Sanlioglu Salih
Published: May 2005

Background

Tumor Necrosis Factor (TNF)-Related Apoptosis-Inducing Ligand (TRAIL) selectively induces apoptosis in cancer cells but not in normal cells. Despite this promising feature, TRAIL resistance observed in cancer cells seriously challenged the use of TRAIL as a death ligand in gene therapy. The current dispute concerns whether or not TRAIL receptor expression pattern is the primary determinant of TRAIL sensitivity in cancer cells. This study investigates TRAIL receptor expression pattern and its connection to TRAIL resistance in breast cancer cells. In addition, a DcR2 siRNA approach and a complementary gene therapy modality involving IKK inhibition (AdIKKβKA) were also tested to verify if these approaches could sensitize MCF7 breast cancer cells to adenovirus delivery of TRAIL (Ad5hTRAIL).

Methods

TRAIL sensitivity assays were conducted using Molecular Probe's Live/Dead Cellular Viability/Cytotoxicity Kit following the infection of breast cancer cells with Ad5hTRAIL. The molecular mechanism of TRAIL induced cell death under the setting of IKK inhibition was revealed by Annexin V binding. Novel quantitative Real Time RT-PCR and flow cytometry analysis were performed to disclose TRAIL receptor composition in breast cancer cells.

Results

MCF7 but not MDA-MB-231 breast cancer cells displayed strong resistance to adenovirus delivery of TRAIL. Only the combinatorial use of Ad5hTRAIL and AdIKKβKA infection sensitized MCF7 breast cancer cells to TRAIL induced cell death. Moreover, novel quantitative Real Time RT-PCR assays suggested that while the level of TRAIL Decoy Receptor-4 (TRAIL-R4) expression was the highest in MCF7 cells, it was the lowest TRAIL receptor expressed in MDA-MB-231 cells. In addition, conventional flow cytometry analysis demonstrated that TRAIL resistant MCF7 cells exhibited substantial levels of TRAIL-R4 expression but not TRAIL decoy receptor-3 (TRAIL-R3) on surface. On the contrary, TRAIL sensitive MDA-MB-231 cells displayed very low levels of surface TRAIL-R4 expression. Furthermore, a DcR2 siRNA approach lowered TRAIL-R4 expression on surface and this sensitized MCF7 cells to TRAIL.

Conclusion

The expression of TRAIL-R4 decoy receptor appeared to be well correlated with TRAIL resistance encountered in breast cancer cells. Both adenovirus mediated IKKβKA expression and a DcR2 siRNA approach sensitized MCF7 breast cancer cells to TRAIL.
Behaviour sequelae following acute Kawasaki disease
Authors: Carlton-Conway Daniel , Ahluwalia Raju , Henry Lucy , Michie Colin , Wood Louise , Tulloh Robert
Published: May 2005

Background

Kawasaki disease is a systemic vasculitis and may affect cerebral function acutely. The aim of the present study was to measure a number of behaviour and social parameters within a cohort of Kawasaki disease patients.

Methods

Parents of children with past diagnosis of Kawasaki disease were recruited to complete several behaviour screening questionnaires. Sixty five sets of questionnaires relating to the patient cohort received were eligible for inclusion. Two control groups were used, a hospital (HC) control and a sibling control (SC) group.

Results

40% of the Kawasaki disease group showed elevated internalising scores in the clinical or borderline-clinical range. This compared with 18% of hospital controls and 13% of sibling controls. Additionally, the Kawasaki disease (KD) group were shown to be experiencing greater overall total difficulties when compared with the controls (KD 13.7, HC 8.6, SC 8.9). The KD group attained higher behavioural scores within the internalising sub-categories of somatic problems (KD 61, HC 57, SC 54) and withdrawn traits (KD 56, HC 53, SC 51). The KD group were also shown to be suffering more thought problems (KD 57, HC 53, SC 50) compared with the controls. Further difficulties relating to conduct (KD 3.3, HC 1.4) and social interactions (KD 6.7, HC 8.3) are also highlighted for the KD group compared with hospital controls. Positron emission tomograms were performed on nine patients to investigate severe behavioural problems. Three showed minor changes, possibly a resolving cerebral vasculopathy.

Conclusion

Kawasaki disease can be associated with significant behavioural sequelae. This is an important consideration in the long-term follow up and referral to a clinical psychologist may be necessary in selected patients.
Vasectomy surgical techniques in South and South East Asia
Authors: Labrecque Michel , Pile John , Sokal David , Kaza Ramachandra CM , Rahman Mizanur , Bodh SS , Bhattarai Jeewan , Bhatt Ganesh D , Vaidya Tika Man
Published: May 2005

Background

Simple ligation of the vas with suture material and excision of a small vas segment is believed to be the most common vasectomy occlusion technique performed in low-resource settings. Ligation and excision (LE) is associated with a risk of occlusion and contraceptive failure which can be reduced by performing fascial interposition (FI) along with LE. Combining FI with intra luminal thermal cautery could be even more effective. The objective of this study was to determine the surgical vasectomy techniques currently used in five Asian countries and to evaluate the facilitating and limiting factors to introduction and assessment of FI and thermal cautery in these countries.

Methods

Between December 2003 and February 2004, 3 to 6 major vasectomy centers from Cambodia, Thailand, India, Nepal, and Bangladesh were visited and interviews with 5 to 11 key informants in each country were conducted. Vasectomy techniques performed in each center were observed. Vasectomy techniques using hand-held, battery-driven cautery devices and FI were demonstrated and performed under supervision by local providers. Information about interest and open-mindedness regarding the use of thermal cautery and/or FI was gathered.

Results

The use of vasectomy was marginal in Thailand and Cambodia. In India, Nepal, and Bangladesh, vasectomy was supported by national reproductive health programs. Most vasectomies were performed using the No-Scalpel Vasectomy (NSV) technique and simple LE. The addition of FI to LE, although largely known, was seldom performed. The main reasons reported were: 1) insufficient surgical skills, 2) time needed to perform the technique, and 3) technique not being mandatory according to country standards. Thermal cautery devices for vasectomy were not available in any selected countries. Pilot hands-on assessment showed that the technique could be safely and effectively performed by Asian providers. However, in addition to provision of supplies, introducing cautery with FI could be associated with the same barriers encountered when introducing FI in combination with LE.

Conclusion

Further studies assessing the effectiveness, safety, and feasibility of implementation are needed before thermal cautery combined with FI is introduced in Asia on a large scale. Until thermal cautery is introduced in a country, vasectomy providers should practice LE with FI to maximize effectiveness of vasectomy procedure.
The effect of Irvingia gabonensis seeds on body weight and blood lipids of obese subjects in Cameroon
Authors: Ngondi Judith L , Oben Julius E , Minka Samuel R
Published: May 2005

Dietary fibres are frequently used for the treatment of obesity. The aim of this study was to evaluate the efficacy of Irvingia gabonensis seeds in the management of obesity. This was carried out as a double blind randomised study involving 40 subjects (mean age 42.4 years). Twenty-eight subjects received Irvingia gabonensis (IG) (1.05 g three time a day for one month) while 12 were on placebo (P) and the same schedule. During the one-month study period all subjects were on a normocaloric diet evaluated every week by a dietetic record book. At the end, the mean body weight of the IG group was decreased by 5.26 ± 2.37% (p < 0.0001) and that of the placebo group by 1.32 ± 0.41% (p < 0.02). The difference observed between the IG and the placebo groups was significant (p < 0.01). The obese patients under Irvingia gabonensis treatment also had a significant decrease of total cholesterol, LDL-cholesterol, triglycerides, and an increase of HDL-cholesterol. On the other hand, the placebo group did not manifest any changes in blood lipid components. Irvingia gabonensis seed may find application in weight lose.
Ventricular metastasis resulting in disseminated intravascular coagulation
Authors: John Thomas , Davis Ian D
Published: May 2005

Background

Disseminated Intravascular Coagulation (DIC) complicates up to 7% of malignancies, the commonest solid organ association being adenocarcinoma. Transitional Cell Carcinoma (TCC) has rarely been associated with DIC.

Case presentation

A 74-year-old woman with TCC bladder and DIC was found to have a cardiac lesion suspicious for metastatic disease. The DIC improved with infusion of plasma and administration of Vitamin K, however the cardiac lesion was deemed inoperable and chemotherapy inappropriate; given the patients functional status. We postulate that direct activation of the coagulation cascade by the intraventricular metastasis probably triggered the coagulopathy in this patient.

Conclusion

Cardiac metastases should be considered in cancer patients with otherwise unexplained DIC. This may influence treatment choices.