1 Ever increasing use of engineered carbon nanoparticles in nanopharmacology for selective imaging, sensor or drug delivery systems has increased the potential for blood platelet-nanoparticle interactions.2 We studied the effects of engineered and combustion-derived carbon nanoparticles on human platelet aggregation in vitro and rat vascular thrombosis in vivo. 3 Multiplewall (MWNT), singlewall (SWNT) nanotubes, C60 fullerenes (C60CS) and mixed carbon nanoparticles (MCN) (0.2-300 mg ml À1 ) were investigated. Nanoparticles were compared with standard urban particulate matter (SRM1648, average size 1.4 mm). 4 Platelet function was studied using lumi aggregometry, phase-contrast, immunofluorescence and transmission electron microscopy, flow cytometry, zymography and pharmacological inhibitors of platelet aggregation. Vascular thrombosis was induced by ferric chloride and the rate of thrombosis was measured, in the presence of carbon particles, with an ultrasonic flow probe. 5 Carbon particles, except C60CS, stimulated platelet aggregation (MCNXSWNT4MWNT4 SRM1648) and accelerated the rate of vascular thrombosis in rat carotid arteries with a similar rank order of efficacy. All particles resulted in upregulation of GPIIb/IIIa in platelets. In contrast, particles differentially affected the release of platelet granules, as well as the activity of thromboxane-, ADP, matrix metalloproteinase-and protein kinase C-dependent pathways of aggregation. Furthermore, particle-induced aggregation was inhibited by prostacyclin and S-nitroso-glutathione, but not by aspirin. 6 Thus, some carbon nanoparticles and microparticles have the ability to activate platelets and enhance vascular thrombosis. These observations are of importance for the pharmacological use of carbon nanoparticles and pathology of urban particulate matter.

During haematogenous metastasis, cancer cells migrate to the vasculature and interact with platelets resulting in tumour cell-induced platelet aggregation (TCIPA). We review: 1 The biological and clinical significance of TCIPA; 2 Molecular mechanisms involved in platelet aggregation by cancer cells; 3 Strategies for pharmacological regulation of these interactions. We conclude that pharmacological regulation of platelet-cancer cell interactions may reduce the impact of TCIPA on cancer biology.

1 Matrix metalloproteinase-2 (MMP-2) plays a role in agonist-and tumour cell-induced platelet aggregation (TCIPA). 2 MMP-2 is synthesized as a proenzyme and is activated at the cell surface by membrane type-1 matrix metalloproteinase (MT1-MMP, MMP-14). 3 The significance of tumour cell-associated MT1-MMP for TCIPA was investigated using human breast carcinoma MCF7 cells stably coexpressing the integrin avb3 with MT1-MMP, cells expressing avb3 alone and mock-transfected cells. 4 Western blot and zymography confirmed that avb3/MT1-MMP cells expressed MT1-MMP and efficiently processed proMMP-2 to MMP-2. 5 Aggregometry, phase-contrast and transmission electron microscopy and flow cytometry were used to characterize TCIPA induced by MCF7 cell lines. 6 The aggregating potency of cells was: avb3/MT1-MMP 4avb3 ¼ mock cells, as shown by aggregometry and phase-contrast microscopy. 7 Electron microscopy revealed close, membrane-membrane interactions between activated platelets and avb3/MT1-MMP cells during TCIPA.

Some agonists of the peroxisome proliferator-activated receptor gamma (PPARgamma) belonging to the thiazolidinedione (TZD) family, as well as the cyclopentenone prostaglandin 15-dPGJ2, have been shown to cause neuroprotection in animal models of stroke. We have tested whether the TZD-unrelated PPARgamma agonist L-796,449 is neuroprotective after permanent middle cerebral artery occlusion (MCAO) in the rat brain. Our results show that L-796,449 decreases MCAO-induced infarct size and improves neurologic scores. This protection is concomitant to inhibition of MCAO-induced brain expression of inducible NO synthase (iNOS) and the matrix metalloproteinase MMP-9 and to upregulation of the cytoprotective stress protein heme oxygenase-1 (HO-1). Analysis of the NF-kappaB p65 monomer and the NF-kappaB inhibitor IkappaBalpha protein levels as well as gel mobility shift assays indicate that L-796,449 inhibits NF-kappaB signaling, and that it may be recruiting both PPARgamma-dependent and independent pathways. In summary, our results provide new insights for stroke treatment.

Treatment with long-acting injectable risperidone compared with previous antipsychotic medications resulted in a higher number of patients not requiring hospitalization, not relapsing, and not requiring hospitalization and not showing relapse, resulting in risperidone being more cost effective per month per patient.It is important to note that real-world variations in adherence would automatically be controlled from within a randomized control trial, and hence, any evaluation of variations in adherence inevitably requires a real-world focus. On the basis of these findings, which were obtained in real-world clinical practice, long-acting injectable risperidone is predicted to be the dominant strategy because it results in effective symptom control and direct medical cost savings. However, because of limitations in methodology, any conclusions should, at this stage, be treated as tentative, and confirmation in more detailed follow-up studies is required. Cost-effectiveness comparisons based on experimental evaluations of relapse minimization strategies are also required. In order to avoid estimation biases in the future, a prospectively designed study is needed.

1 Platelet-leukocyte aggregation (PLA) links haemostasis to inflammation. The role of nitric oxide (NO) and matrix metalloproteinases (MMP-1, -2, -3, -9) in PLA regulation was studied. 2 Homologous human platelet-leukocyte suspensions were stimulated with thrombin (0.1-3 nM) and other proteinase activated receptor-activating peptides (PAR-AP), including PAR1AP (0.5-10 mM), PAR4AP (10-70 mM), and thrombin receptor-activating peptide (1-35 mM). 3 PLA was studied using light aggregometry with simultaneous measurement of oxygen-derived free radicals, dual colour flow cytometry, and phase-contrast microscopy. 4 The release of NO was measured using a porphyrinic nanosensor, while MMPs were investigated by Western blot, substrate degradation assays, immunofluorescence microscopy, and flow cytometry. The levels of P-selectin and microparticles (MP) in PLA were measured by flow cytometry. 5 PLA was also characterized using pharmacological agents: S-nitroso-glutathione (GSNO, 0.01-10 mM), 1H-Oxadiazole quinoxalin-1-one (ODQ, 1 mM), N G -L-nitro-L-arginine methyl ester (L-NAME, 100 mM) and compounds that modulate the actions of MMPs such as phenanthroline (100 mM), monoclonal anti-MMP antibodies, and purified MMPs. 6 PAR agonists concentration-dependently induced PLA, an effect associated with the release of microparticles (MP) and the translocation of P-selectin to the platelet surface. 7 NO and radicals were also released during PLA. Inhibition of NO bioactivity by the concomitant release of free radicals or by the treatment with L-NAME or ODQ stimulated PLA, while pharmacological administration of GSNO decreased PLA. 8 PAR agonist-induced PLA resulted in the liberation of MMP-1, -2, -3, and -9. 9 During PLA, MMPs were present on the cell surface, as shown by flow cytometry and immunofluorescence. 10 PLA led to the activation of latent MMPs to active MMPs, as shown by Western blot and substrate degradation assays. 11 Inhibition of MMPs actions by phenanthroline and by the antibodies attenuated PLA. In contrast, purified active, but not latent, MMPs amplified thrombin-induced PLA. 12 It is concluded that NO and MMP-1, -2, -3, and -9 play an important role in regulation of PAR agonist-induced PLA.

Platelets play an important role in carcinogenesis, but the underlying molecular mechanisms remain poorly understood. To investigate the effects of platelets on in vitro invasion of MCF7 human breast cancer cells, human MCF7 cells were used to study their interactions with platelets using aggregometry and cell invasion chambers. Zymography and quantitative polymerase chain reaction (PCR) were used to study matrix metalloproteinases (MMPs), whereas Western blot was used to study protein kinase C (PKC) ␦ in MCF7 cells. We observed that platelets promoted invasion of MCF7 cells (3-fold increase, p Ͻ 0.05, n ϭ 3) and that this process correlated with a dramatic increase in MMP-9 (8 fold-increase, p Ͻ 0.001, n ϭ 3), which is known to facilitate cancer cell invasion. Because both platelets and MCF7 cells have been shown to release MMP-9, we investigated the cellular source that accounted for this increase. The time course and the use of specific protein synthesis inhibitors demonstrated that most of the increase in MMP-9 levels derived from de novo synthesis of this protease by cancer cells.

Stroke is the second to third leading cause of death and the main cause of severe, long-term disability in adults. However, treatment is almost reduced to fibrinolysis, a therapy useful in a low percentage of patients. Given that the immediate treatment for stroke is often unfeasible in the clinical setting, the need for new therapy strategies is imperative. After stroke, the remaining impairment in functions essential for routine activities, such as movement programming and execution, sensorimotor integration, language and other cognitive functions have a deep and life-long impact on the quality of life. An interesting point is that a slow but consistent recovery can be observed in the clinical practice over a period of weeks and months. Whereas the recovery in the first few days likely results from edema resolution and/or from reperfusion of the ischemic penumbra, a large part of the recovery afterwards is due mainly to brain plasticity, by which some regions of the brain assume the functions previously performed by the damaged areas. Neurogenesis and angiogenesis are other possible mechanisms of recovery after stroke. An understanding of the mechanisms underlying functional recovery may shed light on strategies for neurorepair, an alternative with a wide therapeutic window when compared with neuroprotective strategies.