33 research outputs found

    Interseismic deformation at subduction zones investigated by 2D numerical modeling: case study before the 2010 Maule earthquake

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    We study interseismic deformation preceding the Mw8.8 2010 Maule earthquake by means of two-dimensional finite-element modeling. Our goal is to gain insight into the fundamental factors controlling elastic strain build-up and release in subduction zones, and to evaluate different modeling approaches of surface displacement as observed by GPS. We developed a linear elasticity solver that allows us to implement a realistic subducting plate geometry constrained by geophysical data. We test the influence of subducting plate thickness, variations in the updip and downdip limit of a 100% locked interplate zone, elastic parameters, and velocity reduction at the base of the subducted slab. We compared our modeled predictions with interseismic GPS observations along an EW profile crossing the Maule earthquake rupture area, in order to determine best fitting parameters. Our results indicate little influence of the subducting plate thickness at a given downdip limit, which itself has a strong influence on surface deformation. However, the fit to observations is achieved only after reducing the velocity at the base of the subducted slab below the trench region to 10% of the far-field convergence rate. We link this novel result to complementary numerical models that gradually evolve toward considering longer time-scales and complex rheology in order to evaluate the mechanical meaning of the above mentioned inferred kinematic conditions. This allowed us to link the velocity reduction at the base of subducting slabs with a long-term state of high flexural stress resulting from the mechanical interaction of the slab with the underlying mantle. Even a small amount of theses high deviatoric stresses may transfer towards the upper portion of the slab as strain energy that could participate into the mechanical loading of the megathrust and therefore in triggering large earthquakes there

    Porpora trombotica trombocitopenica (PTT) o sindrome di Moschowitz: una vera urgenza ematologica

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    Summary Introduction Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy caused by congenital or inherited disorders involving the processing of the ultra-large forms of von Willebrand factor. As a result, platelet-rich microthrombi form in the small arterial vessels of various organs, particularly those of the brain, heart, and kidneys. The idiopathic autoimmune form of TTP is the most common. There are various subgroups of acquired TTP associated with HIV infection, sepsis, pregnancy, autoimmune disease, various disseminated malignancies, and drugs. If not promptly treated, TTP is associated with high mortality, making it a true medical emergency. Materials and methods The article is based on a review of the literature published between January and October of 2009. Its aim is to clarify the diagnosis, treatment, and follow-up of TTP. Results Diagnostic criteria include the presence of microangiopathic hemolytic anemia associated with thrombocytopenia in the absence of other obvious causes. Assays of ADAMTS13 activity and titration of acquired antibodies against this enzyme are indicated in the follow-up of disease and as prognostic indicators. Treatment centers around daily plasma exchange associated with immunosuppressant drug therapy, particularly steroids and more recently the monoclonal anti-CD20 antibody rituximab. Discussion Despite improved treatment, TTP is still associated with significant mortality (10–20%), particularly when plasma exchange is initiated late. Relapse also occurs in a substantial proportion of patients (10–40%) although the frequency of this outcome may be reduced by rituximab therapy

    Acquired Hemophilia A Treated with Recombinant Porcine Factor VIII: Case Report and Literature Review on Its Efficacy

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    Acquired hemophilia A (AHA) is a bleeding disorder due to the presence of neutralizing autoantibodies named inhibitors in patients with a previously normal hemostasis. Recent international recommendations suggest the use of bypassing agents or substitutive therapy as the first-line treatment, usually preferring the former. The adequate hemostatic therapy needs an accurate balance between bleeding and thrombotic risks. We report a clinical case of acquired hemophilia A successfully treated with recombinant porcine factor VIII (Susoctocog alfa) as the first-line treatment. Despite the patient having a high-risk thrombotic score and a history of recent myocardial infarction, our experience showed the absence of thrombotic complications related to the use of Susoctocog alfa and a complete restoration of hemostatic parameters. Limited literature is present on the use of recombinant porcine factor VIII as a first-line treatment, and our report supports its use, especially when the thrombotic risk is high

    Thrombotic thrombocytopenic purpura (TTP) or Moschowitz syndrome: a true hematologic emergency

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    Introduction: Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy caused by congenital or inherited disorders involving the processing of the ultra-large forms of von Willebrand factor. As a result, platelet-rich microthrombi form in the small arterial vessels of various organs, particularly those of the brain, heart, and kidneys. The idiopathic autoimmune form of TTP is the most common. There are various subgroups of acquired TTP associated with HIV infection, sepsis, pregnancy, autoimmune disease, various disseminated malignancies, and drugs. If not promptly treated, TTP is associated with high mortality, making it a true medical emergency. Materials and methods: The article is based on a review of the literature published between January and October of 2009. Its aim is to clarify the diagnosis, treatment, and follow-up of TTP. Results: Diagnostic criteria include the presence of microangiopathic hemolytic anemia associated with thrombocytopenia in the absence of other obvious causes. Assays of ADAMTS13 activity and titration of acquired antibodies against this enzyme are indicated in the follow-up of disease and as prognostic indicators. Treatment centers around daily plasma exchange associated with immunosuppressant drug therapy, particularly steroids and more recently the monoclonal anti-CD20 antibody rituximab. Discussion: Despite improved treatment, TTP is still associated with significant mortality (10—20%), particularly when plasma exchange is initiated late. Relapse also occurs in a substantial proportion of patients (10—40%) although the frequency of this outcome may be reduced by rituximab therapy

    Primary hyperparathyroidism: epidemiology, clinical features, diagnostic tools and current management

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    Primary hyperparathyroidism (PHPT) is a clinical condition characterized by overactive parathyroid gland secretion of parathyroid hormone with concurrent alteration of the phosphocalcemic metabolism. We present a literature review on primary hyperparathyroidism addressing key on clinical presentation, causes, medical and surgical treatment at the best of our knowledge. Based on this review we confirm the role of serum calcium and serum level examination, as well as we define the definitive treatment for PHPT being parathyroidectomy. In case of contraindication for surgery, medical treatment can play a relevant role
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