Assemblages' structure and activity of bacterioplankton in northern Adriatic Sea surface waters: a 3-year case study.

The bacterial community, both in terms of community structure (denaturing gradient gel electrophoresis fingerprinting) and activity (exoenzymatic hydrolysis of proteins, polysaccharides and phosphorylated molecules and leucine uptake), was investigated seasonally for 3 years (2004-2006) in a large-scale grid in the northern Adriatic Sea. A high variability characterized the spatial structure of bacterial assemblages and a scarce seasonality was found in all the nine studied stations. Bacterial communities were substantially diverse in the same season of the 3 years, in contrast to what was reported previously for oceanic sites. Assemblages were in general strongly affected by river inputs, especially in spring, when freshwater loads were higher. Finally, a close relationship was found between given assemblages and their patterns of degradation/production activities by applying a multivariate analysis (linear discriminant analysis) to the dataset. The high variability of bacterial community structures and patterns of activity may indicate an ecological response to the high dynamism that characterizes the basin both on a physical and on a biological basis.

B-type natriuretic peptide after open-water and hyperbaric chamber exposure to 10 msw.

INTRODUCTION: Hyperbaric environment exposure in humans has cardiovascular effects mainly characterized by an increase in afterload and a decrease in cardiac output. In a previous study we did not find B-type natriuretic peptide (BNP) changes in healthy volunteers exposed to hyperbaric oxygen while other authors documented a significant increase in N-terminal pro-BNP after scuba diving. On the basis of these data we hypothesized that dry hyperbaric exposure and scuba diving could have different effects on BNP secretion. METHODS: Nine healthy volunteers performed a 1-h open-sea air dive at 10 m depth (T); a few days later they were compressed in air in a hyperbaric chamber (CT) using the same dive profile. Three venous blood samples were drawn for each session: before starting the dives (T0 and CT0), immediately after exiting the water and the chamber (T1 and CT1), and 5 h later (T2 and CT2). RESULTS: A significant increase in plasma BNP was found with respect to baseline conditions after scuba diving both at T1 (median increment +32.69% [interquartile range +25.62 to +65.35%]) and at T2 (+28.03% [+23.08 to +38.92%]) while no differences were documented after the same dive in dry conditions either at CT1 (+1.34% [-17.57 to +33.55%]) or at CT2 (0.00% [17,67 to +21.62%]). DISCUSSION: These preliminary findings show that scuba diving and dry hyperbaric exposure, although at the same environmental pressure, cause different effects on ventricular loads in healthy subjects.

Hormonal responses to a long duration exploration in a cave of 700 m depth.

We studied the hypothalamus-pituitary adrenocortical, hypothalamus-pituitary and hypothalamus-pituitary thyroid system responses to a long duration activity (about 20 h) practiced in a demanding environment, characterized by darkness, low temperature and high humidity, namely alpine potholing. We performed four blood drawings in five elite potholers: (1) the morning before the performance, (2) at the bottom of the cave (-700 m), (3) at the end of the ascent, and (4) after 24 h of recovery. Two blood drawings as controls were performed on the same potholers, at the same resting time and with the same experimental procedures as the previous ones. Friedman two-way ANOVA test evidenced significant changes through the different time intervals for detrended (i.e., test values minus control values) growth hormone (GH) (P = 0.003), detrended cortisol (P = 0.004) and FT4 (P = 0.002), while this was not true for TSH and FT3. Successively pairwise comparisons were done both through the different time intervals and between test and control values. The rise of GH values during the performance underlines the great intensity and long duration characteristic of potholing as well as the possibility that the climbing sit harness can cause problems due to vascular hypo-perfusion. Cortisol data, peaking before entering the cave, suggest that there was a marked anticipatory stress reaction followed by less stressing phase during the performance. Finally, the rise of FT4 is likely due to the typical increase of free fatty acids that usually occurs during endurance exercise.