Ocorrência de ouro nos depósitos pliocénicos da região de Cruz de Pau (Seixal)

Recently had been discovery, in the area of the construction of the Carla Sacramento Athletics Stadium at Cruz de Pau (Seixal), a set of stopes and wells with characteristics of ancient Roman mining activities. The old mining works are incised in pliocene sandy formations with conglomeratic facies, where four preliminary samples were collected in a coarser level with subrounded pebbles. The heavy minerais of those samples were studied in accordance with the Heavy Mineral Concentrate Laboratory of the IGM. The previously mentioned facies has interesting gold percentages and the presence of grey (nodular) and classic monazite, xenotime, cassiterite, spinels s.l., ilmenite and rutile. The morphology of the gold grains as well as the heavy minerals shows two phases of transport; an initial fluvial phase and a secondary aeolian phase influenced their concentracion. The high percentage of toroid grains showing evidence of wind ablation, suggests that this was the main factor for reconcentration of the gold. The amount of gold particles obtained in the concentrates is considerable and in one sample, a grade of 3.2 ppm was calculated. The samples also have been analysed for Au + 34 elements by INAA and ICP-MS, the results of which show similar grades as previously obtained.

Glass in Cultural Heritage – An Introduction

Proceedings of the Chemistry and Conservation Science

Regulação integrada do metabolismo da glucose no estado pós-prandial : fisiologia e reversão de processos patológicos

Resumo: Os mecanismos que regulam a homeostase da glucose no pós-prandial são distintos dos mecanismos desencadeados em situações de jejum. Desta forma o fígado parece desempenhar um papel fundamental na acção periférica da insulina após a refeição através de um mecanismo que envolve os nervos parassimpáticos hepáticos e o óxido nítrico (NO). Esta dissertação procura evidenciar a importância de ambos na fi siologia de manutenção da glicémia pós-prandial e na fi siopatologia da resistência à insulina. Dos resultados obtidos observou-se que após a administração de uma refeição mista o perfi l glicémico foi distinto em animais com ou sem ablação dos nervos parassimpáticos hepáticos. A desnervação parassimpática hepática aumentou as excursões de glucose imediatamente após a refeição. Estas diferenças nas excursões de glucose dependentes do parassimpático ocorreram devido a uma diminuição da clearance de glucose, sem que fosse afectada a taxa de aparecimento de glucose no sangue, a produção endógena de glucose e secreção de insulina ou péptido-C. Este aumento das excursões de glucose revelou-se ser devida à diminuição da clearance de glucose pós-prandial exclusivamente no músculo-esquelético, coração e o rim. Concluiu-se que o fígado teria uma função endócrina nestes três órgãos. Surgiu assim a hipótese dos S-nitrosotiois (RSNOs) poderem mimetizar essa resposta endócrina. Testou-se o seu efeito in vivo na sensibilidade à insulina. Para níveis baixos de sensibilidade à insulina, como jejum, desnervação no estado pós-prandial e resistência à insulina os RSNOs potenciaram a sensibilidade à insulina para valores semelhantes ao pós-prandial indicando-os como potenciais fármacos no tratamento da resistência à insulina. O NO e seus derivados ganharam assim uma evidência cada vez maior na acção periférica da insulina e portanto fez-se uma caracterização dos seus níveis desde a fi siologia à fi siopatologia. Os resultados obtidos nesta dissertação permitiram correlacionar a sintetase de óxido nítrico (NOS), enzima responsável pela síntese de NO como um possível marcador da resistência à insulina. Os resultados obtidos contribuíram substancialmente para compreender os mecanismos fi siológicos e fi siopatológicos de manutenção da glicémia após a refeição, colocando o fígado como órgão primordial na regulação periférica (extra-hepática) da captação de glucose.-------- ABSTRACT: The mechanisms responsible for the postprandial response are different from the ones in the fasted state. Therefore the liver seems to play a fundamental role in postprandial insulin action through a mechanism that evolves the hepatic parasympathetic nerves (HPN) and nitric oxide (NO). This work focused on the importance of both, HPN and NO, on postprandial glycemic control and on the pathophysiology of insulin resistance. We observed that after administration of a mixed meal the glycemic profi les with or without the parasympathetic nerves were distinct, increasing glucose excursions after ablation of HPN.This increase in glucose excursions was due to a decrease on the rate of glucose disappearance in extra-hepatic tissues. Glucose appearance rate, endogenous glucose production and insulin secretion were not related to this mechanism. The increase on glucose excursions after the ablation of hepatic parasympathetic system was due to a decrease on glucose clearance on extra-hepatic tissues, namely skeletal-muscle, heart and kidney. We concluded that the liver has an endocrine function on those tissues increasing their glucose uptake.This mechanism led to propose the hypothesis that S-nitrosothiols (RSNOs) could mimic this mechanism. Therefore RSNOs effects on insulin sensitivity were tested. For low insulin sensitivity levels, i.e. fasted state, ablation of the HPN or insulin resistance state induced by a high sucrose diet RSNOs increased insulin sensitivity to levels normally observed in the postprandial state. These results indicated these drugs as potential pharmacological tools in the treatment of insulin resistance. NO and their derivates emerged as fundamental parts of insulin action. A characterization of nitric oxide and nitric oxide synthase (NOS), the enzyme responsible for NO synthesis was part of the work performed. We concluded that NO could be used as a biomarker for insulin resistance states. This work contributed for understanding the mechanism underlying postprandial glycemic control indicating the liver as a key organ in the regulation of peripheral (extra-hepatic) insulin action.

Role of sympathetic innervation in obesity

Part of the results presented in this thesis were published in the following reference (DOI 10.1016/j.cell.2015.08.055): Wenwen Zeng*, Roksana M. Pirzgalska*, Mafalda M.A. Pereira, Nadiya Kubasova, Andreia Barateiro, Elsa Seixas, Yi-Hsueh Lu, Albina Kozlova, Henning Voss, Gabriel G. Martins, Jeffrey M. Friedman and Ana I. Domingos. Sympathetic Neuro-adipose Connections Mediate Leptin-Driven Lipolysis. Cell 163, 84-94 (2015). The work was also presented through poster presentations at iMED Conference 6.0 (Lisbon, 2014), Sociedade Portuguesa de Bioquímica Meeting (Coimbra, 2014) and Sociedade Portuguesa de Neurociências Meeting (Póvoa de Varzim, 2015).