An introduction to mathematical models of coagulation-fragmentation processes: a discrete deterministic mean-field approach

We summarise the properties and the fundamental mathematical results associated with basic models which describe coagulation and fragmentation processes in a deterministic manner and in which cluster size is a discrete quantity (an integer multiple of some basic unit size). In particular, we discuss Smoluchowski's equation for aggregation, the Becker-Döring model of simultaneous aggregation and fragmentation, and more general models involving coagulation and fragmentation.

Coagulation equations with mass loss

We derive and solve models for coagulation with mass loss arising, for example, from industrial processes in which growing inclusions are lost from the melt by colliding with the wall of the vessel. We consider a variety of loss laws and a variety of coagulation kernels, deriving exact results where possible, and more generally reducing the equations to similarity solutions valid in the large-time limit. One notable result is the effect that mass removal has on gelation: for small loss rates, gelation is delayed, whilst above a critical threshold, gelation is completely prevented. Finally, by forming an exact explicit solution for a more general initial cluster size distribution function, we illustrate how numerical results from earlier work can be interpreted in the light of the theory presented herein.

Effects of coagulation factors and inflammatory cytokines on development of acute myocardial infarction in patients younger than 60 years

Purpose: To investigate the effects of coagulation factors and inflammatory cytokines on acute myocardial infarction (AMI) development in patients younger than 60 years. Methods: In this study, 60 patients admitted to The First Affiliated Hospital of Dalian Medical University (Dalian, China) with AMI and 30 other subjects matched with the patients for age and ethnicity but without AMI were enrolled. Blood samples were collected from the AMI patients and the control subjects after a 12-h fast. Subsequently, the levels of coagulation factors (F) II (FII), VII (FVII), VIII (FVIII), fibrinogen (Fg) and von Willebrand factor (vWF) in plasma were analyzed by enzyme-linked immunosorbent assay (ELISA). The protein expression levels of these coagulation factors were determined by Western blot analysis. Inflammatory factors including C-reactive protein (CRP), tumor necrosis factor-α (TNF-α) and interleukin- 6 (IL-6) were also measured by ELISA. Results: FII, FVII, FVIII, Fg and vWF levels in plasm were significantly higher in AMI patients compared with control subjects (p < 0.01). Furthermore, the protein expression levels of FII, FVII, FVIII, Fg and vWF were also significantly up-regulated in AMI patients compared with those in control subjects. Additionally, no significant difference was observed in CRP between AMI patients and control subjects (p > 0.05). However, TNF-α and IL-6 levels in the plasma of AMI patients were significantly higher than those in control subjects (p < 0.05). Conclusion: The results reveal that the pathogenesis of AMI in patients younger than 60 years might be closely related to the high levels of coagulation factors and inflammatory cytokines in the blood.

Outcomes of global coagulation assays in patients with Philadelphia-negative myeloproliferative neoplasms with respect to genetic determinants of clonal progression

Classical myeloproliferative neoplasms (MPNs) are hematopoietic stem cell disorders that manifest with inflammation, promotion of atherosclerosis, hypercoagulability, fibrosis, and clonal evolution. The complex biological background lends itself to multi-omics studies. We have previously shown that reduced platelet fibrinogen receptor (PFR) expression may follow hyperactivation of plasma-dependent mechanisms, such as tissue factor (TF) release, unbalanced thrombin generation, involvement of protease-activated receptors (PARs). Acetylsalicylic acid (ASA) helped to restore the expression of PFRs. In this study, we enrolled 53 MPN patients, subjecting them to advanced genetic testing (panel of 30 genes in NGS), global coagulation testing (Rotational Thromboelastometry - ROTEM) and cytofluorometric determination of PFRs. ROTEM parameters appear to differ considerably depending on the type of pathology under investigation, cell count, and selected mutations. Essential thrombocythemia (ET) and CALR mutation appear to correlate with increased efficiency of both classical coagulation pathways, with significantly more contracted clot formation times (CFTs). In contrast, primary myelofibrosis (PMF) and polycythemia vera (PV) show greater imbalances in the hemostatic system. PV, probably due to its peculiar hematological features, shows a lengthening of the CFT and, at the same time, a selective contraction of parameters in INTEM with the increase of platelets and white blood cells. PMF - in contrast - seems to exploit the extrinsic pathway more to increase cell numbers. The presence of DNMT3A mutations is associated with reduced clotting time (CT) in EXTEM, while ASXL1 causes reduced maximal lysis (ML). EZH2 could be responsible for the elongation of CFT in INTEM assay. In addition, increased PFR expression is associated with history of hemorrhage and sustained CT time in FIBTEM under ASA prophylaxis. Our findings corroborate the existing models on the connection between fibrosis, genetic complexity, clonal progression, and hypercoagulability. Global coagulation assays and PFR expression are potentially useful tools for dynamic evaluation of treatments’ outcomes.

Key Issues In Inhibitor Management In Patients With Haemophilia.

12 Suppl 1

Elevated Hypercoagulability Markers In Hemoglobin Sc Disease.

Hemoglobin SC disease is a very prevalent hemoglobinopathy, however very little is known specifically about this condition. There appears to be an increased risk of thromboembolic events in hemoglobin SC disease, but studies evaluating the hemostatic alterations are lacking. We describe a cross-sectional observational study evaluating coagulation activation markers in adult hemoglobin SC patients, in comparison with sickle cell anemia patients and healthy controls. A total of 56 hemoglobin SC and 39 sickle cell anemia patients were included in the study, all in steady state, and 27 healthy controls. None of the patients were in use of hydroxyurea. Hemoglobin SC patients presented a significantly up-regulated relative expression of tissue factor, as well as elevations in thrombin-antithrombin complex and D-dimer, in comparison to controls (p<0.01). Hemoglobin SC patients presented lower tissue factor expression, and thrombin-antithrombin complex and D-dimer levels when compared to sickle cell anemia patients (p<0.05). Endothelial activation (soluble thrombomodulin and soluble vascular cell adhesion molecule-1), and inflammation (tumor necrosis factor-alpha) markers were both significantly elevated in hemoglobin SC patients when compared to controls, being as high as the levels seen in sickle cell anemia. Overall, in hemoglobin SC patients, higher hemolytic activity and inflammation were associated with a more intense activation of coagulation, and hemostatic activation was associated with two very prevalent chronic complications seen in hemoglobin SC disease: retinopathy and osteonecrosis. In summary, our results demonstrate that hemoglobin SC patients present a hypercoagulable state, although this manifestation was not as intense as that seen in sickle cell anemia.

Twin-twin Transfusion Syndrome: Neurodevelopmental Screening Test.

Objective To assess the neurodevelopmental functions (cognition, language and motor function) of survivors of twin-twin transfusion syndrome (TTTS). Method Observational cross-sectional study of a total of 67 monochorionic diamniotic twins who underwent fetoscopic laser coagulation (FLC) for treatment of TTTS. The study was conducted at the Center for Investigation in Pediatrics (CIPED), Universidade Estadual de Campinas. Ages ranged from one month and four days to two years four months. Bayley Scales of Infant and Toddler Development Screening Test-III, were used for evaluation. Results Most children reached the competent category and were classified as having appropriate performance. The preterm children scored worse than term infants for gross motor subtest (p = 0.036). Conclusion The majority of children reached the expected development according to their age. Despite the good neurodevelopment, children classified at risk should be monitored for development throughout childhood.

Influência das características das substâncias húmicas aquáticas na eficiência da coagulação com o cloreto férrico

The aim of this study was to verify the influence of the apparent molecular size of aquatic humic substances on the effectiveness of coagulation with ferric chloride. Coagulation-filtration tests using jar test and bench-scale sand filters were carried out on samples of water with true color of approximately 100 Hazen units, prepared with aquatic humic substances of different molecular sizes (F1: < 0.45 µm, F2: 100 kDa - 0.45 µm, F3: 30 - 100 kDa and F4': < 30 kDa). For the water samples with lower apparent molecular size fractions, greater dosages of coagulant was needed to remove the color around 5.0 Hanzen units, mainly because these water samples contain higher concentrations of fulvic acids, which exhibited a larger number of negatively-charged groups.

Pluripotent Reprogramming of Fibroblasts by Lentiviralmediated Insertion of SOX2, C-MYC, and TCL-1A

Reprogramming of somatic cells to pluripotency promises to boost cellular therapy. Most instances of direct reprogramming have been achieved by forced expression of defined exogenous factors using multiple viral vectors. The most used 4 transcription factors, octamer-binding transcription factor 4 (OCT4), (sex determining region Y)-box 2 (SOX2), Kruppel-like factor 4 (KLF4), and v-myc myelocytomatosis viral oncogene homolog (C-MYC), can induce pluripotency in mouse and human fibroblasts. Here, we report that forced expression of a new combination of transcription factors (T-cell leukemia/lymphoma protein 1A [TCL-1A], C-MYC, and SOX2) is sufficient to promote the reprogramming of human fibroblasts into pluripotent cells. These 3-factor pluripotent cells are similar to human embryonic stem cells in morphology, in the ability to differentiate into cells of the 3 embryonic layers, and at the level of global gene expression. Induced pluripotent human cells generated by a combination of other factors will be of great help for the understanding of reprogramming pathways. This, in turn, will allow us to better control cell-fate and apply this knowledge to cell therapy.

Impact of Manaus City on the Amazon Green Ocean atmosphere: ozone production, precursor sensitivity and aerosol load

As a contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia - Cooperative LBA Airborne Regional Experiment (LBA-CLAIRE-2001) field campaign in the heart of the Amazon Basin, we analyzed the temporal and spatial dynamics of the urban plume of Manaus City during the wet-to-dry season transition period in July 2001. During the flights, we performed vertical stacks of crosswind transects in the urban outflow downwind of Manaus City, measuring a comprehensive set of trace constituents including O(3), NO, NO(2), CO, VOC, CO(2), and H(2)O. Aerosol loads were characterized by concentrations of total aerosol number (CN) and cloud condensation nuclei (CCN), and by light scattering properties. Measurements over pristine rainforest areas during the campaign showed low levels of pollution from biomass burning or industrial emissions, representative of wet season background conditions. The urban plume of Manaus City was found to be joined by plumes from power plants south of the city, all showing evidence of very strong photochemical ozone formation. One episode is discussed in detail, where a threefold increase in ozone mixing ratios within the atmospheric boundary layer occurred within a 100 km travel distance downwind of Manaus. Observation-based estimates of the ozone production rates in the plume reached 15 ppb h(-1). Within the plume core, aerosol concentrations were strongly enhanced, with Delta CN/Delta CO ratios about one order of magnitude higher than observed in Amazon biomass burning plumes. Delta CN/Delta CO ratios tended to decrease with increasing transport time, indicative of a significant reduction in particle number by coagulation, and without substantial new particle nucleation occurring within the time/space observed. While in the background atmosphere a large fraction of the total particle number served as CCN (about 60-80% at 0.6% supersaturation), the CCN/CN ratios within the plume indicated that only a small fraction (16 +/- 12 %) of the plume particles were CCN. The fresh plume aerosols showed relatively weak light scattering efficiency. The CO-normalized CCN concentrations and light scattering coefficients increased with plume age in most cases, suggesting particle growth by condensation of soluble organic or inorganic species. We used a Single Column Chemistry and Transport Model (SCM) to infer the urban pollution emission fluxes of Manaus City, implying observed mixing ratios of CO, NO(x) and VOC. The model can reproduce the temporal/spatial distribution of ozone enhancements in the Manaus plume, both with and without accounting for the distinct (high NO(x)) contribution by the power plants; this way examining the sensitivity of ozone production to changes in the emission rates of NO(x). The VOC reactivity in the Manaus region was dominated by a high burden of biogenic isoprene from the background rainforest atmosphere, and therefore NO(x) control is assumed to be the most effective ozone abatement strategy. Both observations and models show that the agglomeration of NO(x) emission sources, like power plants, in a well-arranged area can decrease the ozone production efficiency in the near field of the urban populated cores. But on the other hand remote areas downwind of the city then bear the brunt, being exposed to increased ozone production and N-deposition. The simulated maximum stomatal ozone uptake fluxes were 4 nmol m(-2) s(-1) close to Manaus, and decreased only to about 2 nmol m(-2) s(-1) within a travel distance >1500 km downwind from Manaus, clearly exceeding the critical threshold level for broadleaf trees. Likewise, the simulated N deposition close to Manaus was similar to 70 kg N ha(-1) a(-1) decreasing only to about 30 kg N ha(-1) a(-1) after three days of simulation.

Dust-induced instability in a rotating plasma

The effect of immobile dust on stability of a magnetized rotating plasma is analyzed. In the presence of dust, a term containing an electric field appears in the one-fluid equation of plasma motion. This electric field leads to an instability of the magnetized rotating plasma called the dust-induced rotational instability (DRI). The DRI is related to the charge imbalance between plasma ions and electrons introduced by the presence of charged dust. In contrast to the well-known magnetorotational instability requiring the decreasing radial profile of the plasma rotation frequency, the DRI can appear for an increasing rotation frequency profile. (c) 2008 American Institute of Physics.

Is there a connection between long airplane flight, venous thromboembolism, and sleep-disordered breathing?

Commercial passenger flights have been increasing around the world. The effect of these flights on health is unclear. Venous thromboembolism has been noted after recent long-distance airplane flight, even in the absence of other risk factors. Hypoxia caused by the low ambient pressure during flights could contribute, and individuals with obstructive sleep apnea may be particularly vulnerable. The association between the effects of long airplane travel and sleep-disordered breathing deserves further study. (C) 2008 Elsevier B.V. All rights reserved.

Toxicity and recalcitrant compound removal from bleaching pulp plant effluents by an integrated system: anaerobic packed-bed bioreactor and ozone

Effluents originated in cellulose pulp manufacturing processes are usually toxic and recalcitrant, specially the bleaching effluents, which exhibit high contents of aromatic compounds (e.g. residual lignin derivates). Although biological processes are normally used, their efficiency for the removal of toxic lignin derivates is low. The toxicity and recalcitrance of a bleached Kraft pulp mill were assessed through bioassays and ultraviolet absorption measurements, i.e. acid soluble lignin (ASL), UV(280), and specific ultraviolet absorption (SUVA), before and after treatment by an integrated system comprised of an anaerobic packed-bed bioreactor and oxidation step with ozone. Furthermore, adsorbable organic halides (AOX) were measured. The results demonstrated not only that the toxic recalcitrant compounds can be removed successfully using integrated system, but also the ultraviolet absorption measurements can be an interesting control-parameter in a wastewater treatment.

Effect of HMEC on the consolidation of cement pastes: Isothermal calorimetry versus oscillatory rheometry

Chemical admixtures increase the theological complexity of cement pastes owing to their chemical and physical interactions with particles, which affects cement hydration and agglomeration kinetics. Using oscillatory rheometry and isothermal calorimetry, this article shows that the cellulose ether HMEC (hydroxymethyl ethylcellulose), widely used as a viscosity modifying agent in self-compacting concretes and dry-set mortars, displayed a steric dispersant barrier effect during the first 2 h of hydration associated to a cement retarding nature, consequently reducing the setting speed. However, despite this stabilization effect, the polymer increased the cohesion strength when comparing cement particles with the same hydration degree. (C) 2009 Elsevier Ltd. All rights reserved.

Lopap: A non-inflammatory and cytoprotective molecule in neutrophils and endothelial cells

Lopap (Lonomia obliqua prothrombin activator protease) is a member of the lipocalin family isolated from the extract of L obliqua bristles. Lopap displays serine protease-like activities, including coagulation disturbance, cytokine secretion and antiapoptotic activity in human cultured endothelial cells. Here, we have investigated the effects of the recombinant protein (rLopap) on the inflammatory and apoptotic processes of neutrophils and endothelial cells from male Wistar rats. We found that rLopap did not induce in vivo leukocyte-endothelial interactions in the microvasculature, initial steps of leukocyte recruitment during inflammation. Incubation of rLopap with neutrophils or endothelial cells prevented apoptosis evoked by serum deprivation and induced nitric oxide (NO) production in both cell types, and increased the expression of ICAM-1 by endothelial cells. Simultaneous incubation of endothelial cells or neutrophils with rLopap and N(omega)-nitro-L-arginine methyl ester (L-NAME), a non-specific inhibitor of NO synthases, inhibited NO production and impaired the protection on apoptosis. Differently, incubation of endothelial cells with monoclonal antibody anti ICAM-1 did not change the protection on apoptosis evoked by rLopap. Together, these results indicate that rLopap does not display inflammatory properties in vivo but inhibits apoptosis of neutrophils and endothelial cells depending, at least in part, on NO production. (C) 2009 Elsevier Ltd. All rights reserved.