New discrete-time recurrent neural network proposal for quadratic optimization with general linear constraints.

In this brief, the quadratic problem with general linear constraints is reformulated using the Wolfe dual theory, and a very simple discrete-time recurrent neural network is proved to be able to solve it. Conditions that guarantee global convergence of this network to the constrained minimum are developed. The computational complexity of the method is analyzed, and experimental work is presented that shows its high efficiency.

Regeneración miocárdica: el futuro al alcance de la mano / Myocardial regeneration: future at reach

En los últimos años hemos asistido a un interés creciente por eltratamiento de la insuficiencia cardíaca mediante el trasplante decélulas madre. Mientras que los estudios con células madre de músculo(mioblastos) se iniciaron hace mas de 10 años, la posibilidadde que las células madre de la médula ósea tengan un enorme potencialde diferenciación y proliferación han estimulado la investigacióncon otros tipos de células madre. Estos estudios experimentales handemostrado, en no pocas ocasiones, resultados contradictorios loque ha llevado a posturas enfrentadas en cuanto a la ética de iniciarestudios clínicos. Creemos que es adecuado tratar de ofrecer unavisión crítica sobre la utilización de las células madre en la insuficienciacardíaca. Quizá la pregunta mas difícil de contestar en estemomento es, si la realización de ensayos clínicos esta justificado ono a la luz de los conocimientos actuales o si por el contrario debemosadquirir un conocimiento mucho más preciso de la posibleeficacia de este tipo de tratamiento y de los mecanismos que justificandicha eficacia, antes de siquiera iniciar los estudios en humanos.En nuestra opinión existen suficientes evidencias que justifican eldesarrollo de ensayos clínicos a pesar de que, sin duda, existenmuchos interrogantes que debemos resolver mediante estudios experimentalesen animales

The last few years have witnessed a growing interest in regenerative therapy of the failing heart by cell transplantation. Initial studies with skeletal myoblasts were conducted more than 10 years ago. However, the potential of bone marrow derived cells has more recently led to a flurry of experimental studies generating overall positive but occasionally conflicting results. The ethics of initiating clinical trials with stem cells in patients with heart failure has been questioned. Although laboratory research attempts to overcome a number of questions surrounding the usefulness and safety of cell therapy, the accumulated body of evidence warrants implementation of clinical trials. The earliest of these have now documented the feasibility of cell therapy. It is now appropriate to conduct safety and efficacy studies which, if carefully done, should allow assessment of the extent to which this concept of regenerative therapy can be made a clinical reality (AU)

[Myocardial regeneration: future at reach]. / Regeneración miocárdica: el futuro al alcance de la mano.

The last few years have witnessed a growing interest in regenerative therapy of the failing heart by cell transplantation. Initial studies with skeletal myoblasts were conducted more than 10 years ago. However, the potential of bone marrow derived cells has more recently led to a flurry of experimental studies generating overall positive but occasionally conflicting results. The ethics of initiating clinical trials with stem cells in patients with heart failure has been questioned. Although laboratory research attempts to overcome a number of questions surrounding the usefulness and safety of cell therapy, the accumulated body of evidence warrants implementation of clinical trials. The earliest of these have now documented the feasibility of cell therapy. It is now appropriate to conduct safety and efficacy studies which, if carefully done, should allow assessment of the extent to which this concept of regenerative therapy can be made a clinical reality.

Antioxidant vitamins increase the collagen content and reduce MMP-1 in a porcine model of atherosclerosis: implications for plaque stabilization.

Degradation of extracellular matrix, particularly interstitial collagen, promotes plaque instability and contributes to restenosis after vascular injury. We have explored the effects of vitamins C and E on the collagen content and metalloproteinase-1 (MMP-1) expression after angioplasty in hypercholesterolemic pigs. Iliac angioplasty was performed on 18 minipigs divided into three diet groups: a normal-cholesterol (NC), a high-cholesterol (HC) and a high-cholesterol plus vitamins C+E (HCV). Four weeks later, after sacrifice, the vascular collagen content and MMP-1 protein expression, along with the plasma caseinolytic activity and lipid peroxidation, were measured. MMP-1 was also determined in arterial rings stimulated with native low-density lipoproteins (LDL) isolated from experimental groups. Cholesterol-rich diet augmented plasma lipid peroxidation (P<0.05), reduced the collagen content and increased vascular MMP-1 expression after injury (P<0.05). Enhanced caseinolytic activity (identified as MMP-1) was also observed in HC plasma samples and in supernatants from arterial rings incubated with HC-LDL. Vitamins C and E markedly increased neointimal collagen content (P<0.01), reduced the hypercholesterolemia-induced changes in vascular MMP-1 (P<0.05) and diminished plasma and ex vivo caseinolytic activity. Vitamins C and E may help stabilize atherosclerotic plaque after angioplasty and favor vascular remodeling by increasing collagen content and reducing vascular MMP-1 expression in porcine hypercholesterolemia.

Convergence analysis of a discrete-time recurrent neural network to perform quadratic real optimization with bound constraints.

This paper presents a model of a discrete-time recurrent neural network designed to perform quadratic real optimization with bound constraints. The network iteratively improves the estimate of the solution, always maintaining it inside of the feasible region. Several neuron updating rules which assure global convergence of the net to the desired minimum have been obtained. Some of them also assure exponential convergence and maximize a lower bound for the convergence degree. Simulation results are presented to show the net performance.