Plant response to heavy metal toxicity: comparative study between the hyperaccumulator Thlaspi caerulescens (ecotype Ganges) and nonaccumulator plants: lettuce, radish, and alfalfa

Thlaspi caerulescens (alpine pennycress) is one of the best-known heavy metal (HM) hyperaccumulating plant species. It exhibits the ability to extract and accumulate various HM at extremely high concentrations. In this hydroponic study, the performance of T. caerulescens (ecotype Ganges) to accumulate Cd, Zn, and Cu was compared with that of three nonaccumulator plants: alfalfa (Medicago sativa), radish (Raphanus sativus), and lettuce (Lactuca sativa). Plants were exposed to the separately dissolved HM salts for 7 days at a wide range of increasing concentrations: 0 (control: 1/5 Hoagland nutrient solution), 0.1, 1, 10, 100, and 1000 microM. The comparative study combined chemical, physiological, and ecotoxicological assessments. Excessive concentrations of HM (100 and 1000 microM) affected plant growth, photosynthesis, and phytoaccumulation efficiency. Root exudation for all plant species was highly and significantly correlated to HM concentration in exposure solutions and proved its importance to counter effect toxicity. T. caerulescens resisted better the phytotoxic effects of Cd and Zn (at 1000 microM each), and translocated them significantly within tissues (366 and 1290 microg g(-1), respectively). At the same HM level, T. caerulescens exhibited lower performances in accumulating Cu when compared with the rest of plant species, mainly alfalfa (298 microg g(-1)). Root elongation inhibition test confirmed the selective aptitude of T. caerulescens to better cope with Cd and Zn toxicities. MetPLATE bioassay showed greater sensitivity to HM toxicity with much lower EC(50) values for beta-galactosidase activity in E. coli. Nevertheless, exaggerated HM concentrations coupled with relatively short exposure time did not allow for an efficient metal phytoextraction thus a significant reduction of ecotoxicity.     

Sonographic evaluation of the diaphragm in critically ill patients. Technique and clinical applications

The use of ultrasonography has become increasingly popular in the everyday management of critically ill patients. It has been demonstrated to be a safe and handy bedside tool that allows rapid hemodynamic assessment and visualization of the thoracic, abdominal and major vessels structures. More recently, M-mode ultrasonography has been used in the assessment of diaphragm kinetics. Ultrasounds provide a simple, non-invasive method of quantifying diaphragmatic movement in a variety of normal and pathological conditions. Ultrasonography can assess the characteristics of diaphragmatic movement such as amplitude, force and velocity of contraction, special patterns of motion and changes in diaphragmatic thickness during inspiration. These sonographic diaphragmatic parameters can provide valuable information in the assessment and follow up of patients with diaphragmatic weakness or paralysis, in terms of patient–ventilator interactions during controlled or assisted modalities of mechanical ventilation, and can potentially help to understand post-operative pulmonary dysfunction or weaning failure from mechanical ventilation. This article reviews the technique and the clinical applications of ultrasonography in the evaluation of diaphragmatic function in ICU patients.     

Intrapulmonary percussive ventilation superimposed on spontaneous breathing: a physiological study in patients at risk for extubation failure

Purpose  

Intrapulmonary percussive ventilation (IPV) is a high-frequency ventilation modality that can be superimposed on spontaneous breathing. IPV may diminish respiratory muscle loading and help to mobilize secretions. The aim of this prospective study was to assess the short-term effects of IPV in patients at high risk for extubation failure who were receiving preventive non-invasive ventilation (NIV) after extubation.     

Membrane anchored and lipid raft targeted β-secretase inhibitors for Alzheimer's disease therapy

β-secretase, a key enzyme involved in amyloid-β generation, is an attractive candidate for Alzheimer's disease therapy. Transition-state inhibitors of β-secretase are designed to achieve specificity. However, these inhibitors bind only to the active conformation of the enzyme and as the active β-secretase is sequestered in subcellular compartments, new strategies have to be implemented. We propose that membrane-anchoring of β-secretase inhibitors would render them endocytosis-competent thereby enabling the inhibitors to reach these compartments that harbor active β-secretase. By choosing cholesterol as a membrane anchor, we also enrich the inhibitor in lipid rafts where much of the β-secretase is present. In addition, membrane-anchoring of soluble inhibitors reduces the dimensionality of the inhibitor and consequently increases the inhibitor concentration at the target membrane plane. Such inhibitors have great potential in terms of substrate selectivity and reduced side effects. Not only for β-secretase, this strategy could be applied for many membrane targets that are localized either at the plasma membrane or in the endocytic compartments.     

Diaphragm ultrasonography to estimate the work of breathing during non-invasive ventilation

Purpose  

Ultrasonography allows the direct observation of the diaphragm. Its thickness variation measured in the zone of apposition has been previously used to diagnose diaphragm paralysis. We assessed the feasibility and accuracy of this method to assess diaphragmatic function and its contribution to respiratory workload in critically ill patients under non-invasive ventilation.