Diffusion-aggregation processes with mono-stable reaction terms

This paper analyses front propagation of the equation $u_\tau=[D(u)v_x]_x +f(v) \;\;\; \tau < 0, x \in \mathbb{R}$ where $f$ is a monostable (ie Fisher-type) nonlinear reaction term and $D(v)$ changes its sign once, from positive to negative values,in the interval $v \in[0,1]$ where the process is studied. This model equation accounts for simultaneous diffusive and aggregative behaviors of a population dynamic depending on the population density $v$ at time $\tau$ and position $x$. The existence of infinitely many travelling wave solutions is proven. These fronts are parametrized by their wave speed and monotonically connect the stationary states u = 0 and v = 1. In the degenerate case, i.e. when D(0) and/or D(1) = 0, sharp profiles appear, corresponding to the minimum wave speed. They also have new behaviors, in addition to those already observed in diffusive models, since they can be right compactly supported, left compactly supported, or both. The dynamics can exhibit, respectively, the phenomena of finite speed of propagation, finite speed of saturation, or both

Aggregative movement and front propagation for bi-stable population models

Front propagation for the aggregation-diffusion-reaction equation is investigated, where f is a bi-stable reaction-term and D(v) is a diffusion coefficient with changing sign, modeling aggregating-diffusing processes. We provide necessary and sufficient conditions for the existence of traveling wave solutions and classify them according to how or if they attain their equilibria at finite times. We also show that the dynamics can exhibit the phenomena of finite speed of propagation and/or finite speed of saturation

Positive solutions of BVPs on the half-line involving functional BCs

We study the existence of positive solutions on the half-line of a second order ordinary differential equation subject to functional boundary conditions. Our approach relies on a combination between the fixed point index for operators on compact intervals, a fixed point result for operators on noncompact sets, and some comparison results for principal and nonprincipal solutions of suitable auxiliary linear equations.Comment: 13 page

Continuous dependence in front propagation of convective reaction-diffusion equations

Continuous dependence of the threshold wave speed and of thetravelling wave profiles for reaction-diffusion-convection equationsis here studied with respect to the diffusion, reaction and convection terms

Rheumatologic rehabilitation: the great expectation for rheumatic patients

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Circulating autoantibodies to endothelial progenitor cells: binding characteristics and association with risk factors for atherosclerosis.

OBJECTIVE: Endothelial progenitor cells (EPC) are committed to transform into EC promoting vasculogenic ischemic repair. Anti-endothelial cells (AECA) have been described in various disorders with an associated vascular damage. Herein, we explored a novel circulating population of IgG reactive with EPC, in patients with differential risk profile for atherosclerotic vascular disease. APPROACH AND RESULTS: A novel cyto-ELISA system was established where the coated cells were late outgrowth EPC. Levels of anti-EPC antibodies were determined in 100 subjects and differential risk score for atherosclerosis, as well as to circulating EPC levels and the inflammatory markers IL-6 and C-reactive protein. To study endothelial cell (EC) activating properties, sera were tested for their ability to induce VCAM-1 expression in a cell ELISA system. Detectable levels of anti-EPC antibodies, that correlated with age, Framingham risk score and CRP concentrations but did not associate with levels of LDL, HDL, hypertension or diabetes, were detected. Anti-EPC antibodies were distinct from EC binding antibodies as shown by competitive inhibition studies, and have been positively correlated with the extent of EC activation manifested by in vitro VCAM-1 expression. CONCLUSION: This is the first study showing a newly defined subgroup of self-antibodies binding EPC and associating positively with the Framingham risk score. Further studies are required to characterize and test this interesting subset of EPC binding autoantibodies and their potential significance

Mechanisms of vascular damage in SSc—implications for vascular treatment strategies

Vascular abnormalities are a major component of SSc, but little is known about the events or mechanisms that initiate vascular injury and prevent its repair. In SSc, angiogenesis is incomplete or lacking despite the increased expression of a large array of pro-angiogenic factors such as VEGF. Conflicting results have recently been published concerning the presence and role of vasculogenesis and circulating endothelial progenitor cells in SSc. It remains to be established if these endothelial progenitor cells are a marker of endothelial disease or a cause of insufficient vascular repair. Human mesenchymal stem cells (MSCs) may be an alternative source for endothelial progenitor cells, and it has been observed that the angiogenic potential of endothelial-like MSCs is reduced. Other mechanisms of vascular damage include oxidative stress and factors released from activated platelets. In addition, growth factors such as ET-1 and PDGF induce proliferation of vascular smooth muscle cells resulting in intimal thickening. For the development of new therapeutic strategies, it is important to realize that the different vascular pathologies—uncompensated loss of capillaries on one hand and vascular remodelling with a proliferative vasculopathy on the other—might require different treatment approache

Vasculogenesis and angiogenesis: vascular damage in systemic sclerosis

La sclerosi sistemica (SSc) è una malattia multisistemica del connettivo caratterizzata dalla presenza di alterazioni microvascolari con deficit angiogenetico (1). Suddividendo la patogenesi della SSc in momenti successivi è possibile considerare il microcircolo come la struttura colpita dalla malattia che in più fasi coinvolge l’organismo del paziente affetto da SSc (2). La cellula endoteliale (CE) viene inizialmente attivata tramite una noxa ignota alla produzione di molecole di adesione, chemiochine, citochine e fattori di crescita. In tal modo viene facilitato il passaggio (homing) linfocitario nei tessuti. Inizialmente si ha un danno a carico della CE seguito da un ispessimento dell’intima e da un progressivo restringimento del lume fino alla completa ostruzione del vaso..

The role of the dermatologist in Raynaud’s phenomenon: a clinical challenge

Raynaud’s phenomenon (RP) is a functional vascular disorder involving extremities. In his practice, the dermatologist may frequently encounter RP which affects mainly women and is categorized into a primary benign form and a secondary form associated with different diseases (infections, drugs, autoimmune and vascular conditions, haematologic, rheumatologic and endocrinologic disorders). Still today, the differential diagnosis is a clinical challenge. Therefore, a careful history and a physical examination, together with laboratory tests and nailfold capillaroscopy, is mandatory. RP is generally benign, but a scheduled followâ up for primary RP patients should be established, due to risk of evolution to secondary RP. A combination of conservative measures and medications can help in the management of RP. The importance of avoiding all potential physical, chemical and emotional triggers, as well as quitting smoking, should be strongly suggested to the patient. As firstâ line treatment, dihydropyridine calcium channel blockers should be used. If this approach is not sufficient, prostacyclin derivatives, phosphodiesterases inhibitors and endothelin receptor antagonists can be considered as secondâ line treatment. In cases of acute ischaemia, nifedipine and intravenous prostanoids are helpful. In refractory cases, botulinum injections have shown a significant benefit. The approach to the RP patients requires therefore a coordinated care of specialists together with the primary care physician.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144681/1/jdv14914_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144681/2/jdv14914.pd

Guidelines for initiation of anti-tumour necrosis factor therapy in rheumatoid arthritis: similarities and differences across Europe.

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