The geodynamic origin of Los Humeros volcanic field in Mexico: insights from numerical simulations.

Compared to normal arc-related volcanic eruptions, the formation of a volcanic caldera is a relatively atypical event. During caldera formation a series of large volumes of magma are erupted, reducing the structural support for the rock above the magma chamber and creating a large depression at the surface called caldera. Los Humeros volcanic field (LHVF) represents one of the largest volcanic calderas in Mexico. It is located some 400 km from the trench at the eastern edge of the Trans Mexican Volcanic Belt where the depth to the Cocos slab is more than 300 km. In this study we employ high-resolution two-dimensional thermomechanical numerical simulations of magma intrusions and a horizontal tectonic strain rate to better understand the influence of crustal deformation for the formation of Los Humeros caldera. A minimum number of three thermal anomaly pulses of hydrated mantle material (with diameter of 15 km or more) and a regional strain rate of 7.927 × 10-16 s-1 are required for magma to reach the surface. Modeling results show that regional extension coupled with deep thermal anomalies (with a temperature excess of ΔT ≥ 100 °C) that come in a specific chain-type sequence produce surface deformation patterns similar to LHVF. We propose an asthenospheric sub-slab deep source (> 300 km depth) for the thermal anomalies where previous studies showed the existence of a gap or tear in the Cocos slab.

Numerical modeling of subduction and evaluation of Philippine Sea Plate tectonic history along the Nankai Trough.

The subduction of the Philippine Sea (PHS) plate along the Nankai Trough in in southwest Japan is a relatively recent process compared with subduction along the Japan Trench in northeast Japan. However, the tectonic evolution of the PHS plate along the Nankai Trough is still controversial and not fully understood. There are several competing hypotheses based on different estimates for the time variations of convergence rate and plate age. Our study employs numerical modelling of subduction in order to evaluate the slab evolution for the last 15 Myr and aims to evaluate each tectonic scenario against the present-day slab geometry along a profile passing through the Shikoku and Chugoku regions. The modelling strategy involves a parameter study where subduction initiation and various subduction parameters are analyzed in terms of subduction geometry evolution. Two-dimensional visco-elasto-plastic numerical simulations of spontaneous bending subduction predict that convergence rate and plate age variations play an important role in the evolution of subduction geometry. Modeling results after 15 Myr of evolution reveal that the tectonic model based on a high convergence rate between ~ 15 Ma and ~ 3 Ma produces a slab geometry that agrees well with the observed present-day slab shape specific for the Shikoku and Chugoku regions.

[Penetrating ascending aortic ulcer in an asymptomatic patient]. / Úlcera penetrante de aorta ascendente en un paciente asintomático.

Penetrating aortic ulcer (PAU) has been defined as an atherosclerotic plaque ulceration that breaks the internal elastic lamina of the aorta, which may progress to a wall hematoma or aortic dissection in the case of blood seeping into the middle layer. Although PAU is commonly located in the descending aorta, the involvement of the ascending aorta can be fatal. Therefore, surgery is indicated even in asymptomatic patients presenting an ascending PAU. We report on an asymptomatic patient with ascending PAU referred for replacement of the ascending aorta with a composite prosthetic graft.

Úlcera penetrante de aorta ascendente en un paciente asintomático / Penetrating ascending aortic ulcer in an asymptomatic patient

La úlcera penetrante de aorta (UPA) es la ulceración de una placa aterosclerótica que afecta a la lámina elástica interna de la aorta, y que puede evolucionar hacia un hematoma de pared o una disección aórtica si se produce el paso de sangre hacia la capa media. A pesar de que se localiza más frecuentemente en la aorta descendente, puede presentar una alta mortalidad en caso de situarse en la aorta ascendente, donde la cirugía está indicada aunque el paciente se encuentre asintomático. Presentamos el caso de un paciente sin sintomatología con úlcera penetrante de aorta ascendente (UPAA) ascendente sometido a sustitución de aorta ascendente por una prótesis vascular(AU)

Penetrating aortic ulcer (PAU) has been defined as an atherosclerotic plaque ulceration that breaks the internal elastic lamina of the aorta, which may progress to a wall hematoma or aortic dissection incase of blood seeping into the middle layer. Although PAU is commonly located in the descending aorta, the involvement of the ascending aorta can be fatal. Therefore, surgery is indicated even in asymptomatic patients presenting an ascending PAU. We report on an asymptomatic patient with ascending PAU referred for replacement of the ascending aorta with a composite prosthetic graft(AU)

Gestación interrumpida del segundo trimestre complicada con miocardiopatía dilatada / A pregnancy interrupted in the second trimester complicated by dilated myocardopathy

Presentamos un caso de miocardiopatía dilatada asociada a interrupción de la gestación en la semana 19, que requirió la evacuación inmediata de los restos ovulares mediante microcesárea ante el deterioro progresivo cardiorrespiratorio desde el ingreso. Se llegó al diagnóstico tras no encontrar causa evidenciable alguna a pesar de toda la batería de pruebas de laboratorio realizadas. El ecocardiograma reveló la dilatación del ventrículo izquierdo con hipocinesia generalizada y disfunción sistólica. La paciente precisó de tratamiento intensivo similar al de la insuficiencia cardíaca para estabilizarla. La evolución favorable fue sorprendente y a los 6 meses no presenta secuelas (AU)

We report a case of dilated cardiomyopathy linked to a missed abortion in the 19th week, requiring immediate evacuation of products of pregnancy by means of a microcaesarean because of cardiorespiratory deterioration following admission to hospital. Diagnosis was made excluding other possibilities in spite of extensive laboratory tests, as there was no obvious cause for this. Echocardiogram showed left ventricular dilatation with general hypokinesis and systolic dysfunction. The patient required intensive care to stabilize her cardiac insufficiency. Surprisingly, her evolution was favourable, and after six months she has no sequelae (AU)

Effects of lipoxygenase and cyclooxygenase inhibitors on murine antibody-dependent cellular cytotoxicity (ADCC).

The purpose of this study was to determine the effects that specific inhibition of arachidonic acid (AA) metabolism has on the antibody-dependent cellular cytotoxicity (ADCC) of murine spleen cells. The action of three inhibitors of the lipoxygenase (LO) pathway--nordihydroguaiaretic acid (NDGA), esculetin (Es), and phenanthroline (Phe)--was compared with that of three inhibitors of the cyclooxygenase (CO) pathway--indomethacin (INDO), acetyl salicylic acid (ASA), and imidazole (IMI). All the LO inhibitors suppressed ADCC function in a dose-dependent manner, but NDGA was the most potent inhibitor of this cytolytic activity. In fact, NDGA inhibited the ADCC function with 97% inhibition at 100 microM, while Phe and Es, at the same concentration, inhibited ADCC by 21% and 19%, respectively. However, CO inhibitors did not markedly affect ADCC function and only some doses of them had a slight, but significant, depressing effect (8-11% inhibition at 0.01-0.1 microM of INDO, 7% inhibition at 400 microM of ASA, and 13% inhibition at 800-1000 microM of IMI). These results suggest the LO pathway of the arachidonic acid metabolism plays an important role in regulating ADCC activity of murine spleen cells and the products of the CO pathway have little effect on ADCC lysis.

Fluorimetric determination of indole derivatives by fluorophore generation in copper(II)-sulphuric acid solution.

A spectrofluorimetric procedure for the determination of indole-3-acetic acid, indole-3-propanoic acid and indole-3-butyric acid by derivatization with copper sulphate-sulphuric acid solution has been developed. The optimum reaction conditions, the effect of interferents and the advantages associated with the use of first- and second-derivative synchronous spectrofluorimetry have been studied. The detection limits are 3, 12 and 6 ng/ml for indole-3-acetic, indole-3-propanoic and indole-3-butyric acid, respectively.

Non-aqueous fluorimetric determination of scandium in silicate rocks.

A method for the fluorimetric determination of scandium with 1,2,7-trihydroxyanthraquinone in dimethylformamide medium is described. The calibration graphs obtained by the normal, synchronous, and synchronous first and second derivative techniques are linear between 12 and 225 ng/ml, and the detection limit is 2 ng/ml. The method is applied to the determination of Sc(III) in two simulated and two naturally occurring rocks.