64 resultados para ~(46)Sc


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Thyroid hormone is known to affect myocardial glycogen stores and thereby possibly limit anaerobic performance of mammalian cardiac muscle. Thyroid hormone administration (3,5,T-triiodo-L-thyroxine, 300 mu g/kg/day, sc) for 10 days decreased left ventricle (LV) glycogen concentration relative to euthyroid animals (2.78 +/- 0.46 vs. 4.28 +/- 0.29 mg/g of LV (mean +/- SEM)) while increasing the percent of V(1) myosin isozyi-ne, contractile activity and cardiac mass. In contrast, thyroidectomy increased myocardial glycogen stores (8.50 +/- 0.56 mg/g of LV) and shifted the myosin isozyme toward V(3), prolonged contractile activity and decreased LV mass. Thyroxine administration for 3, 7 and 10 days to thyroidectomized animals progressively decreased contractile duration and increased LV mass. Thyroxine administration for 3 or 7 days to thyroidectomized rats did not reduce glycogen stores (7.75 +/- 1.02 and 9.62 +/- 1.16 mg/g of LV, respectively), whereas myocardial glycogen declined to 3.30 +/- 0.58 mg/g of LV after 10 days of treatment. During hypoxia, cardiac muscle from thyroidectomized rats maintained greater active force and developed less contracture relative to euthyroid and, to a greater extent, than hyperthyroid rats. Removal of glucose from the bath decreased anaerobic performance and impaired recovery; however, myocardium from thyroidectomized rats remained more tolerant to hypoxia than the euthyroid group. Overall, the intrinsic LV glycogen content was positively correlated to anaerobic performance. These data demonstrate that the thyroid state profoundly affects myocardial growth, contractility and anaerobic performance of rat myocardium. Although energy demand may affect function during hypoxia, anaerobic substrate reserve (cardiac glycogen concentration) appears to be the primary factor determining tolerance to hypoxic stress. J. Exp. Zool. 311A:399-407, 2009. (C) 2009 Wiley-Liss, Inc.

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The Taciba and Rio Bonito (lower Triunfo Mbr) formations are divided into six depositional sequences based on cores, gamma-ray and electrical logs from shallow drillings from northern Santa Catarina State, Each sequence is formed by two systems tracts, a lower one, sandy (lowstand) and an upper one, shaly (highstand). The Taciba Formation has three sequences, S 0 to S 0 sequence S 0 has a thick turbidite sandstone at the base (Rio Segredo Member) that pinches out towards the eastern margin and even disappears in the Mafra outcrop area. Sequence S 1 varies from a thin fluvial-estuarine system to a thick turbidite sandstone of a channelized fan system; S 1 upper shaly system tract is marine in well PP-11, and it is glacially-influenced in well PP-10. Sequence S 2 is a thick sand-stone body of shallow marine origin, but restricted to one well (PP-11); its upper shaly tract is dominated by massive siltstones intercalated with thin, distal tempestites. The lower Triunfo Member (or Taciba-Triunfo transition) begins with the arrival of deltaic clastics of sequence S 3 lower tract, coarsening-up from medial- to proximal delta front sandstones. Sequence S 4 is quite similar to S 3, both showing sand-stone progradation from north to south, as opposed to the southwest-sourced transgressive diamictites. Sequence S 5 consists of fluvial deposits at well PP-12, and two transgressive cycles from wells PP-11 to PP-9, each one of them composed of fluvial-estuarine to marine systems. Well PP-10 is an exception, where the lower cycle presents deglaciation to marine deposits.

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The Permo-Carboniferous Harare Group crops out in the Matra area, represented by Campo do Tenente, Mafra and Rio do Sul formations; they correspond in subsurface to Lagoa Azul, Campo Mourão and Tacïba formations. A composite sampling of the Group was performed through drilling of six wells, which average 60 m in depth; three of them cored the depositional sequence here designated as Upper Mafra\Lower Rio do Sul. The Upper Mafra Formation were sampled by TC-4 and BR-5 wells, and it consists of three units: the lower two are sandy, glacial-deltaic and fluvial-deltaic in origin, corresponding to a lowstand tract. The last unit is composed of two dirtying-upward successions of sandstone, diamictite and rhythmite, interpreted as deglaciation/transgressive events, and well represented in BR-5 drilling. The Lower-Rio do Sul Formation (Lontras Shale) is formed by two marine units: the lower one is represented by shale and bioturbated siltstone which culminate the previous deglaciation, transgressive succession, while the upper one, sampled by SL-2 well, is formed by shale and thin, turbidite sandstone, attributed to a highstand tract.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pós-graduação em Geografia - FCT

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Pós-graduação em Geociências e Meio Ambiente - IGCE