Presence Of Microparticles Research Articles

Effect of micropolar lubrication in non-circular hole-entry hybrid journal bearing with constant flow valve restrictor

Purpose In the present scenario of high-speed machines, the use of non-circular hole-entry bearing configuration, i.e. two-lobe, multi-lobe, lemon bore, etc., has becomes unavoidable, as the journal bearings with non-circular configurations provide better stability at high operating speed and heavy dynamic loading. Further, this research aims to show that the presence of micro particles in the lubricants greatly affects performance of the bearings, as their presence leads to non-Newtonian behaviors of the lubricant. Therefore, to consider the effect of these micro particles, the lubricant is modeled as a micropolar lubricant. The present work analyzes the effect of these micropolar lubricants on the performance of hole-entry circular and non-circular (two-lobe) hybrid journal bearings compensated with constant flow valve restrictor and compares with that of Newtonian lubricants. Design/methodology/approach The modified Reynolds equation governing the laminar flow of iso-viscous, incompressible micropolar lubricant in the clearance space of a journal bearing system has been solved using finite element method and appropriate boundary conditions. Further, a comparative analysis between circular and non-circular (two-lobe) hybrid journal bearing compensated with constant flow valve restrictor operating with Newtonian and micropolar lubricant has been presented. Findings The numerically simulated results reveal that the non-circular bearing configuration provides better performance vis-à-vis the circular bearing configuration. Further, the increase in the micropolar effect of the lubricant enhances the performance of circular and the non-circular bearing configurations compared with the Newtonian lubricant. Also, in the case of the non-circular bearing configuration with an offset factor (δ = 1.5), the bearing performance improved compared with (δ = 1.25). Originality/value Many research studies have been done in the area of non-circular hybrid journal bearing with Newtonian lubricants with different types of restrictors, but the non-circular hole-entry constant flow valve-compensated hybrid journal bearing operating with the micropolar lubricant has not been analyzed. Therefore, in the present work, an effort has been made to fill this research gap.

Bone regeneration using injectable BMP-7 loaded chitosan microparticles in rat femoral defect

Injectable chitosan microparticles were prepared using a simple coacervation method under physiologically friendly conditions by eliminating oil or toxic chemical, and employing low temperature and pressure for growth factor stability. Amount of 200ng of bone morphogenetic protein-7 (BMP-7) was incorporated in the chitosan microparticles by two methods: encapsulating and coating techniques. These microparticles were tested in vivo to determine the biological response in a rat femoral bone defect at 6 and 12weeks. Four groups (n=10) were tested which include two groups for BMP-7 incorporated microparticles (by two techniques), microparticles without BMP-7, and defect itself (negative control). Healthy bone formation was observed around the microparticles, which were only confined to the defect site and did not disperse. Histology indicated minor inflammatory response around the microparticles at 6weeks, which reduced by 12weeks. Micro-CT analysis of bone surface density and porosity was found to be significantly more (p<0.05) for microparticles containing groups, in comparison with controls, which suggests that the new bone formed in the presence of microparticles is more interconnected and porous. Collagen fibrils analysis conducted using multiphoton microscopy showed significant improvement in the formation of bundled collagen area (%) in microparticles containing groups in comparison with controls, indicating higher cross-linking between the fibrils. Microparticles were biocompatible and did not degrade in the 12week implant period.

Fabrication and characterization of zirconium cross-linked carboxymethyl cellulose-chitosan microparticles for bone tissue engineering application

Event Abstract Back to Event Fabrication and characterization of zirconium cross-linked carboxymethyl cellulose-chitosan microparticles for bone tissue engineering application Bipin Gaihre1 and A Champa Jayasuriya1, 2 1 The University of Toledo, Department of Bioengineering, United States 2 The University of Toledo Medical Center, Department of Orthopaedic Surgery, United States Introduction: Carboxymethyl cellulose (CMC) and chitosan (CS) are natural biodegradable and biocompatible polymers. CMC is an anionic polymer obtained through chemical modification of cellulose and CS is a cationic polymer derived from chitin and hence being oppositely charged these two polymers can undergo ionotropic gelation[1]. Zirconium (Zr) is a tetravalent cationic metal extensively used in orthopedic implants to promote osseointegration in the form of zirconia and has recently been found to stimulate proliferation and differentiation of human osteoblasts by stimulating different signaling pathways[2]. This study was aimed at developing injectable, non-toxic polyelectrolyte polymer complex microparticles based on Zr as a novel cross-linker. We hypothesize the use of Zr as cross-linker will not induce any cytotoxicity and promote adhesion of osteoblasts into microparticle. Methods: Aqueous solution of CMC (3% w/v) was prepared and added dropwise into the homogenous mixture of zirconium tetrachloride solution (5% w/v) and CS solution (1% w/v) and kept under stirring for 1 h. The volume ratio of CMC to CS was optimized at 1:2 for improved complexation between two polymers. The particles thus obtained were then dried at room temperature for 48 h before further analysis. The surface morphology of microparticles was characterized by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) was done for elemental analysis. Fourier transform-infrared (FTIR) spectrometer in ATR mode was used to characterize the intramolecular interaction between the components in microparticle. In vitro cytotoxicity was assessed using live/dead cell assay kit after culturing the murine pre-osteoblasts (OB-6) in the presence of microparticles up to 10 days. In order to specifically determine the viability of cells attached to microparticle, the microparticles were transferred into separate well of 24 well-plate and then live/dead cell assay was performed on day 5 and 10 and imaged under fluorescence microscope. The percent area of microparticle covered with cells was determined using ImageJ taking visible portion of microparticle. Results and Discussion: The microparticles were spherical in shape with an average diameter of 787±0.045 µm. The surface of the microparticles contained uniform grooves and ridges creating rougher surface as seen on SEM image (Fig. 1B). Few intact cracks were also observed on the surface of microparticles which might be due to the excessive evaporation of solvent and hence high shrinkage during drying process. EDS data obtained showed the presence of Zr along the surface of microparticles. The comparison of FTIR spectrum of CMC, CS and microparticle showed the presence of all characteristic peaks of both CMC and CS on microparticle. Moreover, absorbance band at 1580 cm-1 corresponding to the characteristic band of NH3+ and COO- suggested strong electrostatic interaction and hence complexation between two polymers (Fig. 2). The use of Zr as a cross-linker did not induce any cytotoxicity as most of the cells were viable up to 10 days of culture with microparticles. Fluorescence images of cells seeded microparticle showed adhesion of cells to the surface of microparticle (Fig. 3). The area percent of cells covering microparticle was significantly higher at day 10 (42%) compared to that at day 5 (15%) suggesting the proliferation of cells on microparticle. Conclusion: In this study, an injectable CMC-CS polyelectrolyte complex microparticles with Zr as a novel crosslinker was developed. Based on the results obtained, it can be concluded that polyelectrolyte complexation occurs between CS and CMC which can be developed into injectable microparticles by crosslinking with Zr. Zr used in this study was not cytotoxic and provided a suitable surface for cell adhesion and proliferation by enhancing the surface roughness of microparticle. National Institute of Health (NIH) (grant number R01DE023356)

Circulating Microparticles Alter Formation, Structure, and Properties of Fibrin Clots.

Despite the importance of circulating microparticles in haemostasis and thrombosis, there is limited evidence for potential causative effects of naturally produced cell-derived microparticles on fibrin clot formation and its properties. We studied the significance of blood microparticles for fibrin formation, structure, and susceptibility to fibrinolysis by removing them from platelet-free plasma using filtration. Clots made in platelet-free and microparticle-depleted plasma samples from the same healthy donors were analyzed in parallel. Microparticles accelerate fibrin polymerisation and support formation of more compact clots that resist internal and external fibrinolysis. These variations correlate with faster thrombin generation, suggesting thrombin-mediated kinetic effects of microparticles on fibrin formation, structure, and properties. In addition, clots formed in the presence of microparticles, unlike clots from the microparticle-depleted plasma, contain 0.1–0.5-μm size granular and CD61-positive material on fibres, suggesting that platelet-derived microparticles attach to fibrin. Therefore, the blood of healthy individuals contains functional microparticles at the levels that have a procoagulant potential. They affect the structure and stability of fibrin clots indirectly through acceleration of thrombin generation and through direct physical incorporation into the fibrin network. Both mechanisms underlie a potential role of microparticles in haemostasis and thrombosis as modulators of fibrin formation, structure, and resistance to fibrinolysis.

Microparticle composites on the basis of scrap utilizable in the field of agricultural production

For renovation of functional surfaces of machines and devices for agricultural production it is possible to use, in addition to conventionally used methods, polymers with fillers &amp;ndash; composites. The presence of microparticles in the polymeric matrix improves substantially the abrasive wear resistance and hardness. This contribution describes tribological properties of epoxy resin filled with chips of ferrous metals &amp;ndash; the change of volume losses increase in dependence on the pressure increase (load) having effect on the worn surface. From the carried out experiments the considerable decrease of filled resin losses is evident compared with the resin without filler. At the same time the exponential increase of volume losses with the increased load was quantified in the course of tribological tests.

Features of Microparticle-Associated Procoagulant Activity in Patients with Thrombocytopenias of Immune and Central Origin

Introduction: The risk of bleeding in patients with thrombocytopenia is increased with platelet counts less than 20 or 30 x 109/L. Nevertheless, some patients with thrombocytopenia of peripheral and central origin (immune thrombocytopenia [ITP] and myelodysplastic syndromes [MDS] respectively) have fewer bleeding symptoms than expected. This fact suggests there may be compensatory mechanisms for the thrombocytopenia, such as the presence of microparticles (MPs).Objective: The aim of this study was to evaluate and characterize the microparticle-associated procoagulant activity in ITP and MDS patients with thrombocytopenia.Methods: Thirty-five patients with chronic ITP and twenty-six patients with MDS with a platelet count less than 50 x109/L and twenty-five healthy controls were included. Blood cell counts were determined with a Coulter Ac. T Diff cell counter (Beckman Coulter, Madrid, Spain). Citrated blood was centrifuged at 1,500 g for 15 min at 23°C. Platelet-poor plasma obtained was additionally centrifuged twice at 23°C (15 min at 1,500 g, and 2 min at 13,000 g, [PFP]) and aliquots were stored at -70ºC until analysis.Phosphatidylserine-MP (Ph-MP) and tissue factor-MP (TF-MP)-dependent procoagulant activities were determined with the ZYMUPHEN kits (Hyphen BioMed, Neuville sur Oise, France) following the manufacturer’s instructions.The identification of MP’s cell origin was determined by flow cytometry labeling MPs with Annexin-V-fluorescein and the following specific monoclonal antibodies (mAb) conjugated with phycoerythrin: anti CD41 mAb for platelets, anti CD14 mAb for monocytes, anti CD144 mAb for endothelial cells, anti CD235 mAb for red cells and anti CD45 mAb for leukocytes.APRIL plasma levels were determined by ELISA (DuoSet ELISA, R&D Systems, Minneapolis,MN, USA).Results: Ph-MP associated procoagulant capacity in MDS and ITP patients was higher than in controls (p<0.01) whereas MP-TF associated procoagulant activity was only increased in MDS patients and practically negligible in ITP and control groups (p<0.01).MPs analysis by flow cytometry of seventeen controls, twenty ITP and six MDS patients showed that ITP patients had an increased percentage of MPs from platelets and red cells, whereas MDS had an increased percentage of monocytes derived MPs. Proportion of MPs derived from other cell types were similar to the control group.Increased percentage of monocyte-derived MPs in MDS patients is in accordance with the higher MP-TF-associated capacity observed in this group since monocytes are tissue factor rich cells. Nevertheless, no differences were found in monocyte count with control and ITP groups and monocyte count did not correlate with MPs associated procoagulant activity and the percentage of monocyte-derived MPs.In the ITP group neither MP-Ph-associated procoagulant activity nor the percentage of red cell-derived MPs correlated with red cell count. On the contrary, MP-Ph-associated procoagulant activity and the percentage of platelet-derived MPs inversely correlated with platelet count.ITP is an antibody-mediated autoimmune disease characterized by accelerated platelet destruction. A proliferation-inducing ligand (APRIL) is a factor that promotes B-cell maturation and survival. All patients with ITP and thrombocytopaenia showed higher APRIL plasma levels than MDS and control groups (p<.01), which inversely correlated with platelet count and correlated to MP-Ph-associated procoagulant activity. These observations support the proposed pathogenic role of APRIL in the development of this disease and that the increase in platelet-derived MPs was due to peripheral platelet destruction.Conclusion: Peripheral and central thrombocytopenias might present a MP-associated procoagulant activity to compensate bleeding risk present in these patients. Cellular origin of these MPs differed according to thrombocytopaenia etiology. DisclosuresNo relevant conflicts of interest to declare.

Comparison of microparticles and nanoparticles effects on deformation texture of steel-based composite and nanocomposite fabricated by the ARB process

In this study, the effect of SiC microparticles and nanoparticles on deformation texture of steel-based composite and nanocomposite fabricated by the accumulative roll bonding (ARB) process was investigated. Textural evolution during the ARB process was evaluated using X-ray diffraction. It was found that the presence of microparticles and nanoparticles in the IF steel matrix changed the intensity of texture components and fibers. There was a texture transition from rolling texture to shear one for pure IF steel, steel-based composite, and steel-based nanocomposite. However, the texture transition occurred in different cycles for these samples. It was realized that recrystallization occurred in pure IF steel, steel-based composite, and steel-based nanocomposite after the third, second, and first ARB cycles, respectively. In addition, occurrence of recrystallization in the steel-based composite and nanocomposite was sooner than in pure IF steel. Finally, it was found that with increasing the number of cycles, the fraction of low misorientation angle grain boundaries decreased and the fraction of high misorientation angle grain boundaries increased.

Characterization of Rheology and Release Profiles of Olanzapine-Loaded Lipid-Core Nanocapsules in Thermosensitive Hydrogel

In this study we developed a new drug delivery system for olanzanpine comprised of drug-loaded lipid-core nanocapsules incorporated in a thermosensitive hydrogel, intended to sustain the drug release. Firstly, olanzapine, a hydrophobic drug, was loaded in poly(epsilon-caprolactone) lipid core nanocapsules prepared by interfacial deposition of preformed polymer. The effects of the presence of ethanol and the amounts of sorbitan monostearate and medium-chain triglycerides on the particle size, zeta potential, polydispersity index, presence of microparticles and encapsulation efficiency were investigated using a 2(3) factorial design. The optimized nanocapsules were incorporated into a hydrophilic polymer (Poloxamer 407) dispersion in order to obtain a thermosensitive gel. The formulation containing 0.077 g of sorbitan monostearate, 0.22 ml of medium-chain triglycerides, 3 ml of ethanol and 18% of the thermosensitive polymer was selected according to the physicochemical properties. The rheology and release profiles of the mixed hydrophobic and hydrophilic delivery system were successfully characterized and revealed its great potential for the administration of hydrophobic drugs such as olanzapine with sustained in situ drug release.

Comparison of erosion, corrosion and erosion–corrosion of carbon steel in fluid containing micro- and nanosize particles

This work presents the results of an experimental study on surface damage due to erosion, corrosion and their interactive effect in sea water in the presence or absence of 1 g L−1 suspended nanosize as well as microsize Al2O3 particles. Erosion and erosion–corrosion tests have been conducted on low carbon steel targets using a rotating cylinder system. It is found that nano- and microsize particles act as inhibitors and decrease the pure corrosion rate in comparison to base fluids free of these particles, but over time, the inhibitory effect of microparticles is lost. The presence of microparticles causes more severe steel erosion than sea water, whereas the difference between nanofluid and sea water is not significant. In spite of the effects of nanoparticles on pure corrosion and net erosion, mass loss due to erosion–corrosion in a nanofluid is much higher that the base fluid but is less than the fluid containing microsize particles.

Influence of Particle Size on the Drying Kinetics of Single Droplets Containing Mixtures of Nanoparticles and Microparticles: Modeling and Pilot-Scale Validation

The particle size of the primary particles is an important parameter influencing the drying behavior of droplets. In this work, the influence of particle size on the drying kinetics and grain properties was analyzed for droplets containing silica nanoparticles, microparticles, and mixtures of the two. The presence of microparticles was found to increase the drying rate and shrinkage of the droplet. The drying curves were modeled using a reaction engineering approach (REA) model. Finally, different suspensions were dried in a pilot-scale spray dryer in order to prove the influence of the particle size obtained in the levitator tests.

Using microparticles to enhance micromixing in a high frequency continuous flow sonoreactor

In this paper, an experimental study was conducted to investigate the effect of high frequency ultrasound wave on micromixing efficiency in the presence of polymeric microparticles in a tubular sonoreactor. The size and volume fraction of polymeric microparticles were varied and the micromixing efficiency was studied by adopting the Dushman reaction coupled with a neutralization reaction. In addition, the effect of flow rate and liquid viscosity on the segregation index was studied. The experimental results showed that the movement and dispersion of the polymeric microparticles by ultrasound wave could improve the micromixing efficiency. The results showed that the size of the polymeric microparticles has great effect on mixing. Moreover, it was found that in the presence of these microparticles, segregation index decreases significantly and their effect reduces with increase in the solution viscosity. The presented results show that using high frequency ultrasound waves in the range of MHz and in the presence of microparticles can promise to reach an efficient micromixing in tubular sonoreactors.

Plasma diagnostics for complex plasmas under microgravity and on ground

AbstractComplex plasmas are low-temperature plasmas containing micron-sized particles (microparticles) such as dust grains. These are present in astrophysical systems (comets, molecular clouds, et al.) and in technological applications (microchip production by plasma etching, deposition of solar cells, et al.). Complex plasmas are also of interest in basic science because these are often used as models for many other strongly coupled many-body systems in solid state, fluid, or plasma physics. Since gravity has a strong influence on the microparticle component, experiments under microgravity (parabolic flights, sounding rockets, International Space Station (ISS)) are performed. Interaction between microparticles depends on plasma parameters such as ion density or ion temperature. Also, the presence of microparticles may change the properties of background plasma. Therefore, the background plasma needs to be characterized to provide adequate interpretation of the microgravity experiments. For this purpose a dedicated high-speed diagnostic system has been set up.

Changes of chondrocyte expression profiles in human MSC aggregates in the presence of PEG microspheres and TGF-β3

Biomaterial microparticles are commonly utilized as growth factor delivery vehicles to induce chondrogenic differentiation of mesenchymal stem/stromal cells (MSCs). To address whether the presence of microparticles could themselves affect differentiation of MSCs, a 3D co-aggregate system was developed containing an equal volume of human primary bone marrow-derived MSCs and non-degradable RGD-conjugated poly(ethylene glycol) microspheres (PEG-μs). Following TGF-β3 induction, differences in cell phenotype, gene expression and protein localization patterns were found when compared to MSC aggregate cultures devoid of PEG-μs. An outer fibrous layer always found in differentiated MSC aggregate cultures was not formed in the presence of PEG-μs. Type II collagen protein was synthesized by cells in both culture systems, although increased levels of the long (embryonic) procollagen isoforms were found in MSC/PEG-μs aggregates. Ubiquitous deposition of type I and type X collagen proteins was found in MSC/PEG-μs cultures while the expression patterns of these collagens was restricted to specific areas in MSC aggregates. These findings show that MSCs respond differently to TGF-β3 when in a PEG-μs environment due to effects of cell dilution, altered growth factor diffusion and/or cellular interactions with the microspheres. Although not all of the expression patterns pointed toward improved chondrogenic differentiation in the MSC/PEG-μs cultures, the surprisingly large impact of the microparticles themselves should be considered when designing drug delivery/scaffold strategies.

Meat and Bone Meal and Mineral Feed Additives May Increase the Risk of Oral Prion Disease Transmission

Ingestion of prion-contaminated materials is postulated to be a primary route of prion disease transmission. Binding of prions to soil (micro)particles dramatically enhances peroral disease transmission relative to unbound prions, and it was hypothesized that micrometer-sized particles present in other consumed materials may affect prion disease transmission via the oral route of exposure. Small, insoluble particles are present in many substances, including soil, human foods, pharmaceuticals, and animal feeds. It is known that meat and bone meal (MBM), a feed additive believed responsible for the spread of bovine spongiform encephalopathy (BSE), contains particles smaller than 20 μm and that the pathogenic prion protein binds to MBM. The potentiation of disease transmission via the oral route by exposure to MBM or three micrometer-sized mineral feed additives was determined. Data showed that when the disease agent was bound to any of the tested materials, the penetrance of disease was increased compared to unbound prions. Our data suggest that in feed or other prion-contaminated substances consumed by animals or, potentially, humans, the addition of MBM or the presence of microparticles could heighten risks of prion disease acquisition.

Assessing Consumption of Bioactive Micro-Particles by Filter-Feeding Asian Carp

Silver carp Hypophthalmichthys molitrix (SVC) and bighead carp H. nobilis (BHC) have impacted waters in the US since their escape. Current chemical controls for aquatic nuisance species are non-selective. Development of a bioactive micro-particle that exploits filter-feeding habits of SVC or BHC could result in a new control tool. It is not fully understood if SVC or BHC will consume bioactive micro-particles. Two discrete trials were performed to: 1) evaluate if SVC and BHC consume the candidate micro-particle formulation; 2) determine what size they consume; 3) establish methods to evaluate consumption of filter-feeders for future experiments. Both SVC and BHC were exposed to small (50-100 μm) and large (150-200 μm) micro-particles in two 24-h trials. Particles in water were counted electronically and manually (microscopy). Particles on gill rakers were counted manually and intestinal tracts inspected for the presence of micro-particles. In Trial 1, both manual and electronic count data confirmed reductions of both size particles; SVC appeared to remove more small particles than large; more BHC consumed particles; SVC had fewer overall particles in their gill rakers than BHC. In Trial 2, electronic counts confirmed reductions of both size particles; both SVC and BHC consumed particles, yet more SVC consumed micro-particles compared to BHC. Of the fish that ate micro-particles, SVC consumed more than BHC. It is recommended to use multiple metrics to assess consumption of candidate micro-particles by filter-feeders when attempting to distinguish differential particle consumption. This study has implications for developing micro-particles for species-specific delivery of bioactive controls to help fisheries, provides some methods for further experiments with bioactive micro-particles, and may also have applications in aquaculture.

The characterization and impact of microparticles on haemostasis within fresh‐frozen plasma

We have previously demonstrated that clot formation in fresh-frozen plasma (FFP) is influenced by the presence of microparticles (MP). In this study, the cellular source(s), properties and influence of MPs on clot formation within FFP were further characterized. Fresh-frozen plasma was prepared after an overnight hold of whole blood at 4 degrees C. We examined the effect of a 0.2 microm filtration device designed to remove cellular MPs on thrombin generation test (TGT) and Thrombelastography (TEG(R)) as well as clotting factors and physiological inhibitors: prothrombin time (PT); activated partial thromboplastin time (APTT), fibrinogen (Fg), factor VIII (FVIII), von Willebrand factor antigen (VWF:Ag), antithrombin III (AT-III) and protein C (PC). MPs were measured using a functional assay and also by flow cytometry. Microparticle levels by functional assay were reduced by filtration (pre- 5.11 vs. post- 4.43 nmol/l phosphatidylserine equivalent, P < 0.0001). Flow cytometry showed that the most numerous MPs were derived from red blood cells, with ~87% binding annexin V, most of which (94%) were removed by filtration. MP removal had minimal effect on the PT, APTT, Fg, VWF:Ag, AT-III or PC or FVIII, but a major effect on TGT (endogenous thrombin potential: pre- 1722 vs. post- 990 nM thrombin, P < 0.0001; peak thrombin: pre- 91 vs. post- 44 nM thrombin, P < 0.0001), which in turn reflected the changes seen in TEG(R), where post-filtration clots started forming more slowly and the rate of clot formation was reduced. These data suggest that MPs contribute towards clot formation in FFP.

Hemostatic Dysfunction Associated with Endocrine Disorders as a Major Risk Factor and Cause of Human Morbidity and Mortality: A Comprehensive Meta-review

We review the association between disorders of endocrine function and hemostasis. The content of more than 570 review articles were appraised to provide the core of 81 key articles referenced in this chapter. The search method used MEDLINE and EMBASE electronic databases and the key words e NDOCRINE DYSFUNCTION, DIABETES, GRAVES' DISEASE, HYPOTHYROIDISM, HYPERTHYROIDISM, THYROTOXICOSIS, VON WILLEBRAND DISEASE, VON WILLEBRAND FACTOR, BLEEDING DISORDERS, PLATELETS DYSFUNCTION, HEMOSTASIS DYSFUNCTION, and REVIEW. Abnormalities of hemostasis, platelets, and endothelium and the presence of microparticles, abnormal expression of adhesion molecules, and elevated von Willebrand factor are all associated with cardiovascular disease and are also features of various endocrine disorders, including diabetes and its complications, insulin resistance, polycystic ovary syndrome, and various thyroid disorders. Related causes and associated factors, including obesity, alcohol, hyperlipidemia, omega fatty acids, vitamin D, serotonin, insulin-like growth factors, angiotensin-converting enzyme, and C-reactive protein, are also discussed in this review.

Dying for attention: Microparticles and angiogenesis

See article by Brill et al. [18] (pages 30–38) in this issue. Microparticles, which were initially described as cell dust, have revealed over the past few years several exciting and unexpected properties. Microparticles are submicron vesicles shed from plasma membranes following cell activation or apoptosis, whose protein and lipid profile may be considered as a snapshot of the phenotype of the cell they stem from. The molecular mechanisms of microparticle formation and shedding are not yet fully understood, but seem to involve the changes in the cytoskeleton and exposure of phosphatidylserine on the outer leaflet of the plasma membrane [1,2]. Nevertheless, microparticles can easily be generated in vitro from aggregating platelets or from cultured cells following activation or apoptosis. Microparticles are also found circulating in the blood. Their numbers increase in patients exhibiting hypercoagulability and decrease in those with bleeding disorders [2,3]. Presence of microparticles has also been documented at sites of inflammation such as the acellular lipid core of the atherosclerotic plaque or the synovial fluid from patients with rheumatoid arthritis [3–6]. Furthermore, increased numbers … *Corresponding author. Tel.: +33 1 4463 1864; fax: +33 1 4281 3128. Email address: chantal.boulanger{at}larib.inserm.fr

Diamond-like amorphous carbon coatings for large areas of glass

Diamond-like carbon (DLC) is a metastable form of amorphous carbon with a significant fraction of sp 3 bonding. DLC is a semiconductor having high mechanical hardness, chemical inertness and optical transparency. The films have widespread applications as protective coatings in areas such as magnetic storage disks, optical windows and micro-electromechanical devices (MEMS). To date, such films have been deposited using mass selected ion beams, filtered cathodic vacuum arcs and pulsed laser ablation. These techniques are, however, limited in their areal coverage and throughput. Also, film adhesion to certain substrates, such as soda-lime glass, and the presence of micro-particles are still serious limitations. The primary motivation behind the present work is to develop a large area deposition technique, which produces highly transparent hydrogenated tetrahedral a-C thin films (ta-C:H) that acts as a scratch resistant layer and corrosion barrier on soda lime glass. Large area deposition of DLC, with sp 3 content as high as 80%, directly onto 1.5 m wide glass substrates is reported.

Role of the Tumor Necrosis Factor Receptor 2 (TNFR2) in Cerebral Malaria in Mice

Infection of susceptible mice with Plasmodium berghei Anka leads to a syndrome of severe or cerebral malaria. Tumor necrosis factor (TNF) contributes to this syndrome, apparently by acting on its receptor 2 (TNFR2) because TNFR1-/- are susceptible, whereas TNFR2-/- mice are resistant. In this work, we confirmed the essential role of the TNFR2 in cerebral malaria because 6 to 8 days after Plasmodium berghei Anka infection, hypothermia, coma, and death were observed in +/+ or TNFR1-/-, but never in TNFR2-/-, mice. TNF production, evaluated by the serum levels or the mRNA levels in the brain, spleen or lung, was similar in +/+, TNFR1-/-, or TNFR2-/- mice. Macrophage or parasitized red blood cell sequestration in brain or lung was similar in TNFR1-/- and TNFR2-/- mice. Accordingly, up-regulation of CD54 or CD40 in brain or lung was also similar in TNFR1-/- or TNFR2-/- mice. Platelet loss, manifested by thrombocytopenia and the presence of microparticles in plasma, was similar in TNFR1-/- or TNFR2-/- mice. Breakdown of the blood–brain barrier, detected by the diffusion of tracers, was attenuated in both TNFR1-/- and TNFR2-/-, compared with +/+, mice. Endothelial cells from brain capillaries, examined by transmission electron microscopy, were similar in infected TNFR1-/- or TNFR2-/- mice, whereas the basement membrane was enlarged in TNFR1-/- mice. Hypothermic mice were also hyperglycemic, and this was evident in +/+ and TNFR1-/-, but not in TNFR2-/-, mice. In addition, infected +/+ and TNFR1-/- mice became insulin resistant, while in contrast TNFR2-/- became extremely insulin sensitive. This study supports the possibility that coma and death are mediated not by cell sequestration or breakdown of vascular permeability, similar in TNFR1-/- or TNFR2-/- mice, but by metabolic disturbances selectively mediated by the TNFR2.