Resumo Fundamento: Pré-condicionamento isquêmico remoto (PCIR) é uma terapia para proteção miocárdica, em particular quando é possível prever eventos isquêmicos. Embora vários mecanismos hipotéticos tenham sido propostos, nenhuma via molecular definitiva foi elucidada. Objetivo: Avaliar o efeito da oclusão da circulação braquial com manguito sobre a tolerância à isquemia miocárdica, a necrose miocárdica e a biodisponibilidade de óxido nítrico (NO) em pacientes com cardiopatia isquêmica submetidos a intervenção coronariana percutânea (ICP) eletiva. Métodos: 46 pacientes foram alocados aleatoriamente em dois grupos: controle e PCIR antes da ICP. Análise eletrocardiográfica e medidas da concentração sérica de troponina I (cTn-I) foram realizadas na condição basal e 24 horas após ICP. Coletou-se amostra de sangue da placa aterosclerótica para determinar os níveis de nitratos e nitritos. Resultados: O PCIR aumentou a disponibilidade de NO na artéria coronária que recebeu o stent. O grupo controle apresentou um aumento pequeno, mas significativo, da cTn-I, que permaneceu inalterada no grupo pré-condicionado. O pré-condicionamento não só preservou, como melhorou o somatório de ondas R no eletrocardiograma. Conclusões: O PCIR induziu aumento intracoronariano dos níveis de NO associado com redução do dano miocárdico (medido como aumento da cTn-I) e com aumento do somatório de ondas R, sugerindo melhora miocárdica após ICP eletiva.

Abstract Background: Remote ischemic preconditioning (RIPC) represents an attractive therapy for myocardial protection, particularly when ischemic events can be anticipated. Although several hypothetic mechanisms have been proposed, no definite molecular pathways have been elucidated. Objective: We evaluated the effect of brachial circulation cuff occlusion on myocardial ischemic tolerance, necrosis, and nitric oxide (NO) in patients with ischemic heart disease undergoing elective percutaneous coronary interventions (PCI). Methods: 46 patients were randomly allocated into two groups: control and RIPC before PCI procedures. Electrocardiographic analysis, serum concentrations of troponin I (cTn-I) were measured at baseline and 24 hours after PCI. A blood sample from the atherosclerotic plaque was drawn to determine nitrate and nitrites. Results: RIPC increased the availability of NO in the stented coronary artery. Control patients presented a small but significant increase in cTn-I, whilst it remained unchanged in preconditioned group. The preconditioning maneuver not only preserved but also enhanced the sum of R waves. Conclusions: RIPC induced an intracoronary increase of NO levels associated with a decrease in myocardial damage (measured as no increase in cTn-I) with electrocardiographic increases in the sum of R waves, suggesting an improved myocardium after elective PCI.

This paper describes the first Permian walchian conifer from Mexico based on several specimens preserved as compressions/impressions. The material comes from the Tuzancoa Formation in the state of Hidalgo, Central Mexico. It is described as Calnalia hidalguensis gen. nov. et sp. nov. a new conifer morphotaxon based on isolated lateral branches with leaves. This new conifer has some of the smallest branches and leaves found among previously described walchians. Calnalia hidalguensis has two types of branches (ovoid and deltoid) with simple and helically arranged leaves. Leaves are narrowly triangular to linear in front view, slightly concave and spreading (penultimate shoots) to slightly concave to slightly S-shaped (ultimate shoots), in side view. Leaves range from 3.2 mm long by 0.5 mm wide on penultimate shoots, to 1.3 - 2.9 mm long by 0.4 - 0.9 mm wide on ultimate shoots, with angles of leaf insertion ranging from 16º to 39º. The new species is most similar to Emporia lockardii Mapes and Rothwell, Walchia goeppertiana Florin, Walchia mucronata Florin, and Otovicia hypnoides Kerp, Poort, Swinkels & Verwer. However, none of these have the same ranges of morphological variation found in the leaves of Mexican species. The new taxon expands the diversity of walchian conifers at the end of the Paleozoic in America, and marks the beginning of new research of Permian floras in Mexico. The presence of C. hidalguensis and other gymnosperms, to be described, reinforces the presence of an arc along the Oaxaquia block that connected Mexico to the North American craton during the late Paleozoic. These new data also allow us to test hypotheses about the origin and evolution of Paleozoic floras in Euramerica.

Este artículo describe la primera conífera pérmica "walchiana" con base en varias compresiones e impresiones fósiles de la Formación Tuzancoa en el Estado de Hidalgo, Centro de México. Se describe como Calnalia hidalguensis gen. nov. et sp. nov., un nuevo morfotaxón de coníferas basados en ramas laterales y hojas. Esta nueva conífera tiene unas de las ramas más pequeñas descritas hasta ahora para los miembros "walchianos" en el registro fósil, y cuenta con dos tipos de ramas (ovoide y deltoide), las cuales portan hojas simples con filotaxia helicoidal. Las hojas son ligeramente triangulares a lineares; lateralmente son ligeramente cóncavas a abiertas (penúltimo orden), y ligeramente cóncavas a ligeramente en forma de "S" (último orden). El tamaño de las hojas de penúltimo orden es de 3.2 mm de largo por 0.5 mm de ancho y en las hojas de último orden de 1.3 - 2.9 mm de largo por 0.4 - 0.9 mm de ancho, con ángulos de inserción de las hojas de 16º a 39º. La nueva especie posee mayor similitud con Emporia lockardii Mapes and Rothwell, Walchia goeppertiana Florin, Walchia mucronata Florin y Otovicia hypnoides Kerp, Poort, Swinkels & Verwer. Sin embargo, ninguna de estas especies tiene los mismos rangos de variación morfológica que las hojas de la nueva especie Mexicana presentan. Este nuevo taxón aumenta la diversidad de estas coníferas conocida a finales del Paleozoico en el continente Americano. A su vez, la descripción de esta nueva especie abre la investigación paleobotánica durante el Pérmico en México, y su presencia, así como la de otras especies de plantas aún por describir, refuerzan la teoría de la existencia de un arco a lo largo del bloque Oaxaquilla que conectaba a México con el Cratón de Norteamérica a finales del Paleozoico. Estos datos nos ayudan a proponer hipótesis sobre el origen y evolución de las floras Paleozoicas de Euramérica.

A 54-year male with previous triple vessel coronary artery and aorto-bifemoral bypass graft surgeries complained of crescent angina. Stress induced myocardial ischemia on echocardiography was demonstrated. We performed direct stenting of a saphenous vein graft to the right coronary artery, via right radial approach. Subsequently stenting of a severe left subclavian artery proximal stenosis was performed via right brachial approach in order to relieve an overt myocardial ischemia in the territory supplied by a patent left internal mammary artery graft originated distally to the left subclavian stenosis. The finding of a total left axillary artery occlusion complement the pathogenesis of myocardial ischemia produced by limited anterograde flow and not driven by the common flow reversal mechanism of a typical coronary-subclavian steal syndrome.

Se trata de un paciente masculino de 54 años de edad, con antecedentes de cirugía de revasuclarización miocárdica por enfermedad coronaria trivascular, así como puentes aortobifemorales. Se presentó en nuestro centro aquejando de angina de pecho, de patrón creciente. Se demostró la existencia de isquemia miocárdica, mediante ecocardiografía con estrés farmacológico. Realizamos una angioplastia con stent a un puente de safena inversa a la coronaria derecha por vía radial derecha. Posteriormente debido a una estenosis proximal severa de la arteria subclavia izquerida, implantamos un stent mediante vía braquial derecha, con la idea de mejorar la isquemia existente en el territorio previamente revascularizado por un puente de arteria mamaria izquierda, que se originaba distalmente a la estenosis de la arteria subclavia. El hallazgo de una oclusión total crónica a nivel de la arteria axilar izquierda completó la patogénesis de la isquemia miocárdica no condicionada por robo al flujo coronario, como tradicionalmente sucede en el síndrome de robo subclavio coronario. En este caso particular, el mecanismo isquémico fue debido al compromiso anterógrado de flujo, provocado por la estenosis severa de la arteria subclavia.

In this paper we study the design of dynamic compensators for linear singular control systems described by the equation Ex ´(t) = Ax(t) + Bu(t) with time delayed observed output y(t) = Cx(t - r). The proposed compensators are applied to solve the regulator problem for the mentioned systems with controlled output z(t) = Dx(t).