Cytoskeleton actin-binding proteins in clinical behavior of pituitary tumors

Although generally benign, pituitary tumors are frequently locally invasive, with reduced success of neurosurgery and unresponsive to pharmacological treatment with somatostatin or dopamine analogues. The molecular basis of the different biological behavior of pituitary tumors are still poorly identified, but a body of work now suggests that the activity of specific cytoskeleton proteins is a key factor regulating both the invasiveness and drug resistance of these tumors. This review recapitulates the experimental evidence supporting a role for the actin-binding protein filamin A (FLNA) in the regulation of somatostatin and dopamine receptors expression and signaling in pituitary tumors, thus in determining the responsiveness to currently used drugs, somatostatin analogues and dopamine receptor type 2 agonists. Regarding the regulation of invasive behavior of pituitary tumoral cells, we bring evidence to the role of the actin-severing protein cofilin, whose activation status may be modulated by dopaminergic and somatostatinergic drugs, through FLNA involvement. Molecular mechanisms involved in the regulation of FLNA expression and function in pituitary tumors will also be discussed.

[Reference concentrations of dietary consumption of xenobiotics]

Total diet studies are the best tool to evaluate food exposure to xenobiotics. These studies are based on xenobiotic concentrations measured in foods that are related to food consumption data in order to obtain reliable assessment of xenobiotic food intakes. This work is a review of the main international literature and points out international, European and Italian data of xenobiotic food ingestion. In particular, it focuses on metals, trace elements, polycyclic aromatic hydrocarbons (PAHs) and some mycotoxin intakes in the total diet. Recorded data show that xenobiotic ingestion differs from nation to nation in relation to environmental pollution and contamination, geographical and climatic conditions, food habits and consumption. Therefore, in order to define reference values for xenobiotic food exposure, it is necessary to set up a monitoring and risk surveillance program by collecting data in a permanent and systematic way. Nevertheless, we have hypothesized some xenobiotic reference values for the area of Pavia based on local studies.

[Survey on environmental contamination in the total diet of an Italian population]

This work is a review of the total diet studies carried out in the nineties in the area of Pavia in order to evaluate food exposure to some xenobiotics: heavy metals (cadmium, mercury, lead, nickel), polycyclic aromatic hydrocarbons (PAHs), pesticides and mycotoxins. The review shows that: total diet studies are the best tool to evaluate food exposure to xenobiotics; however, the studies utility depends both on the presence of an actual correlation between xenobiotic food exposure and xenobiotic concentration in human body and depends also on environmental distribution of the xenobiotic. It's the case of the mycotoxins which, characterised by a punctiform contamination, can be studied only with analytical studies on biological samples, e.g. human milk. The results point out that some groups of the population are at risk because of high xenobiotic food ingestions above the acceptable daily intakes. In conclusion, we suggest that total diet studies should be carried out in a more systematic way in order to obtain effective surveillance and preventive programmes, besides we underline that the definition of reference values may be of great utility.

Communication and cooperation in networked environments: an experimental analysis

Interpersonal communication and cooperation do not happen exclusively face to face. In work contexts, as in private life, there are more and more situations of mediated communication and cooperation in which new online tools are used. However, understanding how to use the Internet to support collaborative interaction presents a substantial challenge for the designers and users of this emerging technology. First, collaborative Internet environments are designed to serve a purpose, so must be designed with intended users' tasks and goals explicitly considered. Second, in cooperative activities the key content of communication is the interpretation of the situations in which actors are involved. So, the most effective way of clarifying the meaning of messages is to connect them to a shared context of meaning. However, this is more difficult in the Internet than in other computer-based activities. This paper tries to understand the characteristics of cooperative activities in networked environments--shared 3D virtual worlds--through two different studies. The first used the analysis of conversations to explore the characteristics of the interaction during the cooperative task; the second analyzed whether and how the level of immersion in the networked environments influenced the performance and the interactional process. The results are analyzed to identify the psychosocial roots used to support cooperation in a digital interactive communication.

Acute respiratory distress syndrome caused by pulmonary and extrapulmonary disease. Different syndromes?

To assess the possible differences in respiratory mechanics between the acute respiratory distress syndrome (ARDS) originating from pulmonary disease (ARDSp) and that originating from extrapulmonary disease (ARDSexp) we measured the total respiratory system (Est,rs), chest wall (Est,w) and lung (Est,L) elastance, the intra-abdominal pressure (IAP), and the end-expiratory lung volume (EELV) at 0, 5, 10, and 15 cm H2O positive end-expiratory pressure (PEEP) in 12 patients with ARDSp and nine with ARDSexp. At zero end-expiratory pressure (ZEEP), Est,rs and EELV were similar in both groups of patients. The Est,L, however, was markedly higher in the ARDSp group than in the ARDSexp group (20.2 +/- 5.4 versus 13.8 +/- 5.0 cm H2O/L, p < 0.05), whereas Est,w was abnormally increased in the ARDSexp group (12.1 +/- 3.8 versus 5.2 +/- 1.9 cm H2O/L, p < 0.05). The IAP was higher in ARDSexp than in ARDSp (22.2 +/- 6.0 versus 8.5 +/- 2.9 cm H2O, p < 0.01), and it significantly correlated with Est,w (p < 0. 01). Increasing PEEP to 15 cm H2O caused an increase of Est,rs in ARDSp (from 25.4 +/- 6.2 to 31.2 +/- 11.3 cm H2O/L, p < 0.01) and a decrease in ARDSexp (from 25.9 +/- 5.4 to 21.4 +/- 55.5 cm H2O/L, p < 0.01). The estimated recruitment at 15 cm H2O PEEP was -0.031 +/- 0.092 versus 0.293 +/- 0.241 L in ARDSp and ARDSexp, respectively (p < 0.01). The different respiratory mechanics and response to PEEP observed are consistent with a prevalence of consolidation in ARDSp as opposed to prevalent edema and alveolar collapse in ARDSexp.

[Hypertonic saline solutions in resuscitation in hemorrhagic shock. An experimental study]

The aim of the study was to evaluate the use of hypertonic solutions in restoring intravascular volume in a model of hemorrhagic shock. Eighteen pigs underwent general anesthesia and were instrumented with a carotid catheter to record mean arterial pressure (MAP), a pulmonary artery catheter for pulmonary arterial pressure (MPAP) and cardiac output (CO) monitoring and an electromagnetic flowmeter around the abdominal supraceliac aorta for aortic flow measurement (Vaor). Oxygen delivery (DO2) and oxygen consumption (VO2) data were calculated by standard formulas. The animals were hemorrhaged to a MAP of 45 mmHg, held for 1 hour. They were resuscitated during the following hour until the aortic flow regained its basal value, using three different solutions: normotonic saline (NS = NaCl 0.9%), hypertonic saline (HS = NaCl 7.5%), hypertonic saline added with dextran (HSDX = NaCl 7.5% + 6% dextran 70). An hour of autologous blood transfusion and a two hours follow-up concluded the experiment. Volumes infused were remarkably lower administering HS (13.70 +/- 1.44 ml/kg) and HSDX (9.11 +/- 1.20 ml/kg) compared to NS (90.32 +/- 24.83 ml/kg). MAP, CO and DO2 values resulted significantly higher in the HSDX animals, with lower MPAP levels. During the two hours follow-up only the animals reinfused with HSDX maintained hemodynamic and oxygen transport values at normal levels. We conclude that the administration of hypertonic saline solutions during hemorrhagic shock allows the saving of infusion volumes, thus diminishing the occurrence of interstitial edema formation. The adding of dextran to the solution prolongs the hemodynamic effects.

Prone positioning improves pulmonary function in obese patients during general anesthesia

We investigated the effects of prone position on functional residual capacity (FRC), the mechanical properties (compliance and resistance) of the total respiratory system, lung and chest wall, and the gas exchange in 10 anesthetized and paralyzed obese (body mass index more than 30 kg/m2) patients, undergoing elective surgery. We used the esophageal balloon technique together with rapid airway occlusions during constant inspiratory flow to partition the mechanics of the respiratory system into its pulmonary and chest wall components. FRC was measured by the helium dilution technique. Measurements were taken in the supine position and after 15-30 min of prone position maintaining the same respiratory pattern (tidal volume 12 mL/kg ideal body weight, respiratory rate 14 breaths/ min, fraction of inspired oxygen [FIO2]0.4). We found that FRC and lung compliance significantly (P < 0.01) increased from the supine to prone position (0.894 +/- 0.327 L vs 1.980 +/- 0.856 L and 91.4 +/- 55.2 mL/cm H2O vs 109.6 +/- 52.4 mL/cm H2O, respectively). On the contrary, the prone position reduced chest wall compliance (199.5 +/- 58.7 mL/cm H2O vs 160.5 +/- 45.4 mL/cm H2O, P < 0.01), thus total respiratory system compliance did not change. Resistance of the total respiratory system, lung, and chest wall were not modified on turning the patients prone. The increase in FRC and lung compliance was paralleled by a significant (P < 0.01) improvement of PaO2 from supine to prone position (130 +/- 31 vs 181 +/- 28 mm Hg, P < 0.01), while PaCO2 was unchanged. We conclude that, in anesthetized and paralyzed obese subjects, the prone position improves pulmonary function, increasing FRC, lung compliance, and oxygenation.