RESUMEN
Total hip replacements (THR) with modular femoral components (stem-neck interface) make it possible to adapt to extramedullary femoral parameters (anteversion, offset, and length) theoretically improving muscle function and stability. Nevertheless, adding a new interface has its disadvantages: reduced mechanical resistance, fretting corrosion and material fatigue fracture. We report the case of a femoral stem fracture of the female part of the component where the modular morse taper of the neck is inserted. An extended trochanteric osteotomy was necessary during revision surgery because the femoral stump could not be grasped for extraction, so that a long stem had to be used. In this case, the patient had the usual risk factors for modular neck failure: he was an active overweight male patient with a long varus neck. This report shows that the female part of the stem of a small femoral component may also be at increased failure risk and should be added to the list of risk factors. To our knowledge, this is the first reported case of this type of failure.
Asunto(s)
Artroplastia de Reemplazo de Cadera/efectos adversos , Prótesis de Cadera , Fracturas Periprotésicas/cirugía , Diseño de Prótesis , Falla de Prótesis , Artroplastia de Reemplazo de Cadera/métodos , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Sobrepeso , Fracturas Periprotésicas/diagnóstico , Recuperación de la Función , Reoperación/métodos , Estrés Mecánico , Resultado del TratamientoRESUMEN
The phosphatidylinositol-3-kinase (PI3K)/AKT/mTOR signaling pathway is a central regulator in cell proliferation, growth, and angiogenesis. Inhibition of this pathway therefore is a major strategy for cancer chemotherapy. In order to induce the maximal therapeutic outcome in cancer treatment, vertical inhibition of the PI3K/AKT/mTOR pathway or horizontal inhibition of PI3K/AKT/mTOR and other kinases has been reported. In this review, we discuss the drug design and clinical development of dual inhibitors of PI3K and mTOR as well as the mTOR-selective inhibitors, classified based on the mechanism of action and the chemical structures. Structural determinants for increasing selectivity toward PI3Kα or mTOR are revealed from the structure-activity relationship of the reported inhibitors. Current clinical development in combination therapy of inhibitors involving in the PI3K/AKT/mTOR pathway is also discussed.
Asunto(s)
Inhibidores Enzimáticos/farmacología , Inhibidores de las Quinasa Fosfoinosítidos-3 , Serina-Treonina Quinasas TOR/antagonistas & inhibidores , Animales , Humanos , Terapia Molecular Dirigida/métodos , Neoplasias/tratamiento farmacológico , Neoplasias/enzimología , Transducción de Señal/efectos de los fármacos , Relación Estructura-Actividad , Especificidad por SustratoRESUMEN
An important problem in vision is to detect the presence of a known rigid 3-D object. The general 3-D object recognition task can be thought of as building a description of the object that must have at least two parts: 1) the internal description of the object itself (with respect to an object-centered frame); and 2) the transformation of the object-centered frame to the viewer-centered (image) frame. The reason for this decomposition is parsimony: different views of the object should have minimal impact on its description. This is achieved by factoring the object's description into two sets of parameters, one which is view-independent (the object-centered component) and one which is view-varying (the viewing transformation). Often a description of the object is known beforehand and the task reduces to finding the objectframe to viewer-frame transformation. This paper describes a method for handling this case: a known object is detected by finding changes in orientation, translation, and scale of the object from its canonical description. The method is a Hough technique and has the characteristic insensitivity to occlusion and noise.