Modelling the risk of mortality of Corbicula fluminea (Müller, 1774) (Bivalvia: Corbiculidae) exposed to different turbidity conditions.

The provision of sediment in rivers, due to erosion processes that occur in the environment, consists of a major source of pollution and alteration of the physicochemical conditions of water resources. In addition, the increase in water turbidity may cause siltation, dramatically impacting aquatic communities. Specifically considering the bivalve Corbicula fluminea (Müller, 1774), the aim of this study was to analyse the effect of exposure to different turbidity conditions of sediments, as a risk factor for the animals. For this purpose, a docking device was designed to ensure water circulation in a closed system and to maintain the desired levels of turbidity. Although C. fluminea can generally tolerate environmental changes in aquatic systems, an intolerance to high turbidity levels was experimentally observed, expressed by the mortality rate of the animals when exposed to conditions above 150 nephelometric turbidity units (NTU). This value was similar to the one recorded at study sites in the rivers Pardo (Serrana-SP-Brazil) and Mogi Guaçu (Porto Ferreira-SP-Brazil) during the rainy season. Using a logistic regression model, the experimental results were analysed and the observed mortality rates indicate that the exposure of the animals to turbidity levels above 150 nephelometric turbidity units (NTU), for periods longer than 120 hours, may be considered a probable cause of mortality for the species.

[Acute paraplegia secondary to painless aortic dissection]. / Paraplejía aguda secundaria a la disección indolora de la aorta.

INTRODUCTION: Acute aortic dissection (AAD) is a serious and uncommon event. The clinical presentation generally includes thoracic or back pain. Painless aortic dissection is an extremely rare occurrence. Acute paraplegia is one of the neurological complications secondary to AAD. Although painful paraplegia is seen in 2% to 3% of AAD cases, painless paraplegia is a very rare event. CASE REPORT: A 51-year-old man with a long term history of hypertension, presented with acute paralysis of the lower extremities, with no chest or back pain. CONCLUSION: In presence of acute neurologic events, must always be investigated a vascular cause and, in these group of disease, the aortic dissection may be researched, although the pain wasn't present on occasion of the diagnosis.

Headache in transient ischaemic attacks.

Headaches were studied in a series of 49 patients with single or multiple transient ischaemic attacks (TIAs) followed up for 27 +/- 17 months. Forty-two patients had a CT scan and 38 had a Duplex-Scan. Twelve patients (24%) had TIA-related headaches, mostly in close temporal relation to the ischaemic onset. Headaches were more frequent in females and in vertebrobasilar TIA. Headache predominated in patients taking vasodilators when TIA occurred, or with orthostatic hypotension at the first clinical examination, suggesting that haemodynamic mechanisms are of importance in this respect. Bilateral/median pain predominated, especially but not exclusively in patients with vertebrobasilar territory TIAs. Arterial hypertension or a personal history of migraine were not more frequent in patients with headache. Patients with multiple TIAs had stereotyped headaches. Data suggest that headache and transient ischaemia are closely related. Reflex mechanisms may induce pain far from the ischaemic territory.