RESUMO: Este trabalho resulta de um esforço de vários anos tentando usar a geologia de campo para descrever litologias, estabelecer relações de contato e perfazer a evolução tectônica das sucessões metassedimentares, de idades meso a neoproterozoicas, que foram deformadas dentro da Faixa de Xistos do Cinturão Dom Feliciano. Essas rochas constituem uma cobertura de baixo grau que repousa em cima do embasamento de alto grau metamórfico dos complexos La China e Las Tetas. Esse embasamento é de idade paleoproterozoica-arqueana. A Faixa de Xistos é sotoposta em discordância angular pela formação Barriga Negra. O Complexo Lavalleja e a formação Barriga Negra se deformaram junto durante o evento D2 (~ 570 - 540 Ma), mas a formação Barriga Negra registrou apenas parcialmente o evento transpressivo D2, enquanto o Complexo Lavalleja foi afetado pelos dois eventos (D1 e D2). O evento D1 teria desenvolvido uma dobra - nappe com vergencia para o sul. Essa hipótese é sustentada por diferentes estruturas: (i) dobras recumbentes e dobras retas orientadas E-W, (ii) Foliação subhorizontal milonítica em mármores (calco-xistos); (iii) lineações de estiramento mergulhando para SW em metaconglomerados do Complexo Las Tetas, e (iv) retrabalhamento da foliação subhorizontal, paralelamente à zona de cisalhamento transcorrente Sarandí del Yí.

ABSTRACT: This work is the result of a multiyear effort to use field geology to describe lithologies, to establish contact relationships and to create a sketch of the tectonic evolution of the Meso- to Neoproterozoic metasedimentary successions within the Schist Belt of the Dom Feliciano Belt. This low-grade metamorphic cover rests on the high-grade metamorphic basement of the La China and Las Tetas complexes. This basement is Archean-Paleoproterozoic in age. The Schist Belt is overlapped unconformably by the Barriga Negra formation. The Lavalleja complex and the Barriga Negra formation both deformed together during the D2 deformation event (~ 570 -540 Ma), but the Barriga Negra only partially recorded the D2 transpressive event, whereas the Lavalleja complex was affected by both the D1 tangential event and the D2 event. Event D1 would have developed a fold nappe with vergence to the south. This hypothesis is supported by different structures: (i) recumbent and upright folds oriented E-W, (ii) subhorizontal mylonitic foliation in marbles (calc-schists), (iii) stretching lineations plunging towards the SW in metaconglomerates of the Las Tetas Complex, and (iv) a reworking of the subhorizontal foliation parallel to the Sarandí del Yí strike-slip shear zone.

Abstract Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is a maternally inherited mitochondrial disease with a broad spectrum of manifestations. In addition to impaired energy production, nitric oxide (NO) deficiency occurs in MELAS syndrome and leads to impaired blood perfusion in microvasculature that can contribute to several complications including stroke-like episodes, myopathy, and lactic acidosis. The supplementation of NO precursors, L-arginine and L-citrulline, increases NO production and hence can potentially have therapeutic utility in MELAS syndrome. L-citrulline raises NO production to a greater extent than L-arginine; therefore, L-citrulline may have a better therapeutic effect. The clinical effect of L-citrulline has not yet been studied and clinical studies on L-arginine, which are limited, only evaluated the stroke-like episodes’ aspects of the disease. Controlled studies are still needed to assess the clinical effects of L-arginine and L-citrulline on different aspects of MELAS syndrome.

El Haz de Diques de San Gregorio de Polanco (Departamento de Tacuarembó, Uruguay) es la ocurrencia más meridional de diques pertenecientes a la Provincia Magmática Paraná en Uruguay. Fueron identificados cinco 5 diques principales con dos direcciones estructurales principales: N140º - N170º y N50º - N80º, respectivamente. Son diques de afinidad tholeítica compuestos por plagioclasa (An55), augita y augita-pigeonita, relictos de olivina y minerales opacos. Estos diques se caracterizan por el alto contenido de óxidos de Fe y Ti (titanomagnetitas), cuyas características mineralógicas y texturales fueron estudiadas con microscopio electrónico de barrido y espectrometría de energía dispersiva (SEM-EDS), incluyendo mapeos composicionales. Estas características junto con otras relaciones mineralógico-texturales presentes en estas rocas permitieron proponer la siguiente secuencia de cristalización: (i) cristalización de fenocristales de olivina, plagioclasa y piroxenos cálcicos; (ii) precipitación de una primera población de titanomagnetita, (iii) cristalización de plagioclasa y piroxenos conformando la matriz; (iv) disolución parcial de la primera población de titanomagnetitas por reacción con fluidos magmáticos; (v) cristalización de la segunda población de titanomagnetitas y finalmente, (vi) cristalización de barita intersticial.

The San Gregorio de Polanco Dike Swarm (Tacuarembó Department, Uruguay) is the southernmost set of dikes in the Paraná Magmatic Province of Uruguay. Five major dikes have been identified with two main structural trends: N140º-N170º and N50º-N80º. The dikes have tholeiitic affinities and are composed of plagioclase (An55), augite and augite-pigeonite, relicts of olivine and opaque minerals. These rocks have high contents of Fe-Ti oxides (titanomagnetites), the mineralogical and textural characteristics of which have been studied using scanning electron microscopy and energy dispersive spectrometry techniques (SEM - EDS). These features, along with other mineralogical and textural relationships, have been used to propose the following crystallization sequence for the dikes: (i) crystallization of olivine, plagioclase and Ca-rich pyroxene phenocrysts; (ii) precipitation of the first population of Ti-magnetite; (iii) crystallization of plagioclase and pyroxene in the groundmass; (iv) partial dissolution of Ti-magnetite by reaction with magmatic fluids; (v) crystallization of the second population of Ti-magnetite and finally, (vi) crystallization of interstitial barite.

Background The advent and the development of drug eluting stents (DES) have reduced the prevalence of restenosis according to different series; however, its incidence still remains significant. Genetic factors contribute to restenosis and thus should be taken into account and undergo thorough investigation. Some polymorphisms are known to have a relation with in-stent restenosis: platelet polymorphism and endothelial nitric oxide synthase gene polymorphism. Objective To demonstrate if platelet IIb-IIIa (PlA2) and endothelial nitric oxide synthase (eNOS) gene polymorphisms (Glu298Asp, -786T>C, 922A/G and 420/393) present greater risk of in-stent restenosis after coronary angioplasty (PTCA). Material and Methods A coronary angiography was performed in 92 patients who had undergone PTCA in the previous 1 to 12 month, due to suspected restenosis. Patients were divided in two groups: with angiographic restenosis (<50%) (cases) and without restenosis (controls). A polymerase chain reaction (PCR) was performed for each polymorphism using specific restriction enzymes. Multiple logistic regression analysis included clinical, angiographic and genetic factors. Results Age, gender and risk factors were similar among both groups (cases = 41 patients with restenosis, controls: 51 patients without restenosis). A 60% of drugs eluting stents were implanted in each group. The rate of restenosis in patients with PlA2 polymorphic allele was significantly greater than in non carriers (21.9% versus 1.9%, OR 14.1, 95% CI 1.7-116.3; p=0.002). Patients with variant allele for 922A/G polymorphism showed a similar behavior (41.5% versus 19.6%, OR 2.9, 95% CI 1.2-7.4; p=0.02). The prevalence of restenosis was similar in both groups in patients with 298Asp, 420/393 and 786T-C polymorphisms. Multivariate analysis revealed that PlA1/A2 was the only predictor of restenosis (p=0.02). Conclusions This study demonstrates that PlA2 polymorphic allele is an independent predictor of in-stent restenosis; its detection might have important clinical implications in decisionmaking.

Introducción Con la aparición y el desarrollo de los stents liberadores de droga (SLD), los porcentajes de reestenosis han disminuido según lo demuestran distintas series, pero igualmente siguen siendo clínicamente significativos. Factores genéticos contribuyen a ello, por lo que éstos constituyen una de las causas que deben tenerse en cuenta e investigarse a fondo. Se conocen algunos polimorfismos que presentan una bien documentada relación con la reestenosis intrastent, entre ellos el polimorfismo plaquetario y el de la óxido nítrico sintetasa endotelial. Objetivo Demostrar si el polimorfismo plaquetario IIb-IIIa (PlA2) y de la óxido nítrico sintetasa endotelial (eNOS) (Glu298Asp, -786T>C, 922A/G y 420/393) presentan mayor riesgo de reestenosis intrastent posangioplastia coronaria (ATC). Material y métodos La población estuvo compuesta por 92 pacientes con ATC realizada entre 1 y 12 meses previos a la inclusión en el estudio, en los que se efectuó una angiografía por sospecha clínica de reestenosis. Se consideraron casos las reestenosis angiográficas (> 50%) y controles a los pacientes sin reestenosis. Se realizó la prueba de la reacción en cadena de la polimerasa (PCR) para cada polimorfismo con enzimas de restricción específicas. Se efectuó un análisis de regresión logística múltiple, que incluyó factores clínicos, angiográficos y genéticos. Resultados Entre los casos y los controles, 41 pacientes con reestenosis y 51 sin reestenosis, respectivamente, la edad, el sexo y los factores de riesgo fueron similares. Se utilizó un 60% de stents liberadores de droga por grupo. Los pacientes con alelo polimórfico PlA2 tuvieron una tasa de reestenosis significativamente mayor que los no portadores (21,9% versus 1,9%, OR 14,1, IC 95% 1,7-116,3; p = 0,002). Algo similar se observó con el polimorfismo 922A/G (41,5% versus 19,6%, OR 2,9, IC 95% 1,2-7,4; p = 0,02). El resto de los polimorfismos (298Asp, 420/393 y 786T-C) mostraron una frecuencia similar de reestenosis en ambos grupos. En el análisis multivariado, el PlA1/A2 fue el único predictor independiente de reestenosis (p = 0,02). Conclusiones Este estudio muestra que el alelo polimórfico PlA2 es un predictor independiente de riesgo de reestenosis intrastent coronario y su detección podría tener implicaciones importantes en la toma de decisiones.