O complexo Atuba: um cinturão paleoproterozóico intensamente retrabalhado no Neoproterozóico

Studies of terranes between the northern Ribeira and southern Dom Feliciano Belts allow the characterization of three geotectonic domains with different evolutions: the Luís Alves, Curitiba and Paranaguá terranes. The Atuba Complex occurs in the Curitiba Domain, which has a northwestern limit with metassediments of the Açungui and Setuva Groups and a southwestern limit with the granulitic gneisses of the Luis Alves domains. The contacts are expressive shear zones. The predominant rocks of the Curitiba Domain are banded, migmatitic gneisses in amphibolite grade with biotite-amphibole gneissic mesosomes and tonalitic/granodioritic to granitic leucosomes, here called the Atuba Complex. The migmatites are Paleoproterozoic (2.000 ± 200 Ma) and remigmatized in Neoproterozoic (600 ± 20 Ma). During the latter period temperatures reached more than 500º C. The structural pattem indicated shear-controlled tectonics with an important lateral component, and low-angle, south-southeastwards transport direction. The terranes of the Atuba Complex appear to represent deep-level rocks which were migmatized, granitized and then added to the border of the Luis Alves Microplate during the Neoproterozoic. This late Neoproterozoic tectonic scheme which continued to the Cambro-Ordoviciano seems to be the result of larger-scale processes of continental agglutination which ended with the formation of western Gondwanaland.Os estudos realizados nos terrenos localizados entre os Cinturões Ribeira (N) e Dom Feliciano (S) permitiram caracterizar a existência de três domínios geotectônicos com evoluções próprias e distintas: Domínios Luis Alves, Curitiba e Paranaguá. O Complexo Atuba se insere no âmbito do Domínio Curitiba, que se limita a noroeste com as seqüências metassedimentares dos Grupos Açungui e Setuva, e a sudeste com os gnaisses granulíticos do Domínio Luis Alves, contatos esses que se fazem por importantes zonas de cisalhamento. Predominam no Domínio Curitiba rochas gnáissicas bandadas, migmatíticas, do fácies anfibolito, representadas principalmente por biotita-anfibólio-gnaisses contendo leucossomas de composições tonalitogranodioríticas além de graníticas, que compõem o aqui denominado Complexo Atuba. Caracteriza-se por migmatitos formados no Paleoproterozóico (2.000 ± 200 Ma), remigmatizados no Neoproterozóico (600± 20 Ma), período esse em que as isotermas atingiram temperaturas superiores a 500 ºC. O padrão estrutural observado é indicativo de uma tectônica controlada em grande parte por cisalhamento, com importante componente lateral, e transporte relativo em direção a sul-sudeste. As rochas pertencentes ao Complexo Atuba representam terrenos relativamente profundos, do fácies anfibolito, migmatizados, granitizados acrescidos à borda do Domínio Luis Alves (Microplaca Luis Alves) durante o Neoproterozóico. Este quadro tectônico definido no final do Neoproterozóico com continuidade até o Cambro-Ordoviciano, parece ser o resultado de processos maiores, envolvendo aglutinações de massas continentais, que culminaram com a formação do Gondwana Ocidental

Urocortin 2 - a protective effect in hypertension?

Urocortin 2, an endogenous selective ligand for the corticotropin-releasing hormone receptor type 2, has been suggested to exert cardioprotective effects. We analyzed the possible relationship between the level of Ucn2 and specific indicators of cardiovascular risk factors in patients with untreated hypertension and in healthy subjects. Sixty seven subjects were recruited: 38 with newly diagnosed treatment-naive hypertension (with no pharmacological treatment - HT group) and 29 healthy subjects without hypertension (nHT group). We evaluated ambulatory blood pressure monitoring, Ucn2 levels and metabolic indices. Multivariable regression analyses were performed to assess the effects of gender, age, and Ucn2 levels on metabolic indices or blood pressure (BP) level. Log of Ucn2 levels were higher in healthy subjects than in hypertensive patients (2.44±0.7 versus 2.09±0.66, p<.05) and correlated inversely with 24-hour diastolic blood pressure, and both night-time systolic and diastolic blood pressure regardless of age and gender (R2=0.06; R2=0.06; R2=0.052; respectively). Furthermore, Ucn2 levels inversely correlated with cholesterol and low-density cholesterol (LDL) concentrations in healthy subjects only. Ucn2 was independently related to total cholesterol (but not to LDL) regardless of age, gender and the presence of hypertension (R2=0.18). However, we did not find any relationship between urocortin 2, body mass index or waist-hip ratio as well as parameters of glucose metabolism. Our data indicates that higher levels of urocortin 2 are related to more favorable lipid profiles and lower blood pressure