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Emilia Sforza, Fréderic Roche Service de Physiologie Clinique et de l'Exercice, Pole NOL, CHU, EA SNA-EPIS 4607, Faculté de Médecine J. Lisfranc, UJM Saint-Etienne, Université de Lyon, Saint-Etienne, France Abstract: Obstructive sleep apnea (OSA) is a prevalent sleep disorder considered as an independent risk factor for cardiovascular consequences, such as systemic arterial hypertension, ischemic heart disease, cardiac arrhythmias, metabolic disorders, and cognitive dysfunction. The pathogenesis of OSA-related consequence is assumed to be chronic intermittent hypoxia (IH) inducing alterations at the molecular level, oxidative stress, persistent systemic inflammation, oxygen sensor activation, and increase of sympathetic activity. Overall, these mechanisms have an effect on vessel permeability and are considered to be important factors for explaining vascular, metabolic, and cognitive OSA-related consequences. The present review attempts to examine together the research paradigms and clinical studies on the effect of acute and chronic IH and the potential link with OSA. We firstly describe the literature data on the mechanisms activated by acute and chronic IH at the experimental level, which are very helpful and beneficial to explaining OSA consequences. Then, we describe in detail the effect of IH in patients with OSA that we can consider "the human model" of chronic IH. In this way, we can better understand the specific pathophysiological mechanisms proposed to explain the consequences of IH in OSA. Keywords: hypoxia, intermittent hypoxia, experimental studies, obstructive sleep apnea

In view of an efficient industrial autotrophic cultivation of microalgal biomass, the role of light into photobioreactor is still to be fully ascertained. The influence of different light intensities was investigated using both continuous illumination and alternation of light and dark cycles with different frequencies, which mimic illumination variations in a photobioreactor due to mixing. In order to minimize the effect of cell self- shading all experiments were carried out in thin layer flat plate reactor (which can be operated both in batch and continuous mode), where microalgae were cultivated under a non-limiting CO2 supply, with CO2- enriched air bubbled through the culture. In this apparatus, we measured growth rate, lipid content and photosynthetic performances of Scenedesmus obliquus. The species showed a maximum growth rate at about 150 µmol of photons m-2 s-1. Above this value the growth was inhibited, while the algae was found still able to exploit light, even if at lower efficiency, and showed a decreased pigment content. The resistance of the species to high irradiances was confirmed also in continuous experiments, where microalgae were found able to adapt to high illumination, leading to an increased steady state concentration and higher productivity at 350 µmol m-2 s-1 (about 3 g L-1 d-1). In addition, by changing the residence time, a maximum in productivity was found. The lipid content, constitutively high, was not affected by the variation light intensity, making this species suitable to industrial application. Furthermore, the alternation of light and dark cycles with different frequencies was studied both in batch and continuous experiments. Cultures exposed to pulsed light shows a drastically reduced growth compared to continuous light.

Amebic abscess is a common manifestation of extraintestinal amebiasis and it is associated with relatively high morbidity and mortality. We present three cases seen in Bari, Southern Italy, one of which was autochthonous and the other two were not. Diagnosis was performed by elevated antibody titre for E. histolytica through immunofluorescence assay and positive antigen determination by ELISA in stools and in abscess aspirate. Fever often accompanied by chills, abdominal pain, weight loss and hepatomegaly were present. Laboratory findings also revealed leukocytosis with neutrophilia. Pleural effusion was observed in two patients. In all our patients multiple abscesses were observed. All the patients were treated with metronidazole and two of them also underwent the aspiration of the amoebic abscess. In all of them there was improvement of the clinical picture, as demonstrated by computerized tomography.

Fatal familial insomnia is a prion disease in which a selective thalamic degeneration leads to total sleep deprivation, hypertension, dysautonomia, adrenal overactivity, and impaired motor functions. With patients under continuous recumbency and polysomnographic control, we assessed the changes in the 24-hour patterns of blood pressure, heart rate, plasma catecholamines, corticotropin, and serum cortisol in three patients at different stages of the disease. Six healthy volunteers were used as control subjects. A dominant 24-hour component was detected at rhythm analysis of all variables, both in patients and control subjects. In the patients, the amplitudes gradually decreased as the disease progressed, leading to the obliteration of any significant dirunal variation only in the preterminal stage. A shift in phase corresponded to the loss of the nocturnal fall in blood pressure in an early stage of the disease, when nocturnal bradycardia was still preserved. Plasma cortisol was high and became increasingly elevated, whereas corticotropin remained within normal levels; abnormal nocturnal peaks appeared in their circadian patterns. The disrupted patterns of cortisol and blood pressure preceded the development of hypertension and severe dysautonomia, which in turn were paralleled by increasing catecholamine and heart rate levels. Our data demonstrate that in patients with fatal familial insomnia the changes detectable in the rhythmic component of diurnal blood pressure variability result in a pattern of secondary hypertension. Disturbances in thalamic, pituitary-adrenal, and autonomic functions seem to be involved in mediating these changes.