[ECMO treatment in acute lung failure : Who profits?] / ECMO-Therapie beim akuten Lungenversagen : Wer profitiert?

In intensive care medicine, rapid technical developments that are often beneficial to patients are taking place. On the other hand, there are also voices that generally criticize an increasing "interventionalism". This area of tension includes other important questions regarding usefulness, quality, ethical compliance, scientific evidence, structural capacities and economy. The treatment of acute respiratory distress syndrome (ARDS) using extracorporeal membrane oxygenation (ECMO) is an example of these considerations. Although ECMO has rarely been prospectively evaluated according to scientific criteria, it is still used with an increasing tendency, not least since the documented register survival rates in ECMO patients with severe ARDS are 60%. However, the implementation of this therapy means an immense effort. The necessary centralization and certification for ECMO treatment is currently under intensive discussion. Closely related to this are considerations about which criteria represent good quality in patient care. In order to be able to guarantee high quality, a precise indication is the first step. And here indications and contraindications still need to be defined. It has not yet been sufficiently clarified which prognosis factors need to be taken into account. This article summarizes what is known about ECMO prognosis and indication criteria. In conclusion, parameters are identified that should be developed scientifically in the future.

[Study protocol to improve the quality of delirium management in intensive care]. / Protokoll einer Studie zur Qualitätsverbesserung des Delirmanagements auf der Intensivstation.

BACKGROUND: Delirium in cardiac surgery patients is common and is associated with prolonged mechanical ventilation and hospital stay as well as higher mortality. Protocols may improve outcome. In our cardiac surgery intensive care unit (ICU), patients with delirium have not received standardized treatment so far. HYPOTHESIS: In cardiac surgery ICU patients, standardized delirium management will lead after a 4­week introduction, compared to nonstandardized treatment, to a reduction of delirium duration. METHODS: Prospective before/after study to evaluate a quality improvement project for delirium management over 12 weeks including 140 patients. INCLUSION CRITERIA: (a) ≥18 years, (b) consent for research with their data. EXCLUSION CRITERIA: (a) palliative status, (b) present during both the before/after phase, (c) pregnancy, (d) included in a competitive study, or (e) delirium not assessable. The implementation includes the introduction of a protocol with interprofessional training, bedside-teaching, pocket cards, posters, and reminders. The primary outcome is the duration of delirium, assessed four times a day with validated instruments. Secondary outcome measures include delirium incidence, duration of mechanical ventilation, length of stay in ICU and hospital, mortality, nursing/therapeutic interventions, cumulative doses of delirium-related drugs, and complications of delirium for a follow-up of 28 days. Empirical data will be analyzed with descriptive and inferential statistics. OBJECTIVES: The purpose of the study is a reduction of the duration and frequency of delirium in cardiac ICU patients and will provide evidence of the effect size of the introduction of a delirium management.

Mapping of the p56lck-mediated phosphorylation of GAP and analysis of its influence on p21ras-GTPase activity in vitro.

The protein tyrosine kinase p56lck and other members of the src family can transduce signals from activated cell-surface receptors. As we showed earlier the GTPase-activating protein (GAP), a regulator of p21ras, is a substrate of p56lck. Here, tryptic peptides of p56lck-phosphorylated GAP were generated and analyzed by two-dimensional thin layer chromatography and mass spectroscopy. Results revealed that p56lck phosphorylates GAP specifically on Tyr-460 in vitro and in vivo. The effect of tyrosine phosphorylation of GAP on its GTPase-activating activity versus p21ras was then tested using a p21ras-dependent GTPase assay system. Our results demonstrate that p56lck-mediated tyrosine phosphorylation of GAP is not sufficient to change directly its effect on the intrinsic GTPase activity of p21ras.

Ras GTPase-activating protein: a substrate and a potential binding protein of the protein-tyrosine kinase p56lck.

Ras GTPase-activating protein (GAP) is a cytoplasmic factor that regulates the GTPase activity of p21ras. Phosphorylation of GAP on tyrosine has recently been reported by several groups and may be an important step in linking signaling pathways involving p21ras and protein-tyrosine kinases. p56lck, a src-like protein-tyrosine kinase, seems to play a crucial role in T-cell development and T-cell activation. However, the molecular mechanisms of T-cell signaling involving p56lck and the substrates of p56lck have not yet been identified. To test whether GAP is a substrate of p56lck, in vitro kinase reactions were performed with purified, recombinant GAP and p56lck. We found that GAP became specifically phosphorylated on tyrosine within one tryptic peptide. Furthermore, coimmunoprecipitation studies provided evidence that the tyrosine-phosphorylated form of GAP is bound to p56lck. These results suggest that in T cells the function of GAP might be regulated through its phosphorylation on tyrosine and binding to the protein-tyrosine kinase p56lck.

The Src homology 2 domain of the protein-tyrosine kinase p56lck mediates both intermolecular and intramolecular interactions.

A key event in signaling by many cell surface receptors is the activation of Src-like protein-tyrosine kinases and the assembly of protein complexes at the plasma membrane mediated by Src homology 2 and 3 (SH2 and SH3) domains. p56lck is a Src-related protein-tyrosine kinase which has SH2 and SH3 domains and is involved in T-cell signaling and oncogenic transformation. Here we demonstrate that purified recombinant SH2 and HSH3/SH2 domains of p56lck can mediate intermolecular interactions with a number of tyrosine-phosphorylated proteins present in lysates of NIH 3T3 cells transformed by a constitutively activated form of p56lck (p56lckF505). Two of the interacting tyrosine-phosphorylated proteins were identified as the p85 subunit of phosphatidylinositol 3-kinase and the GTPase-activating protein of p21ras. Using a synthetic phosphopeptide corresponding to the tyrosine-phosphorylated carboxyl terminus of p56lck (amino acids 494-509), purified recombinant Lck SH2 domain, and differentially phosphorylated forms of p56lck we provide evidence that the SH2 domain of p56lck can also mediate intramolecular interactions with the phosphorylated carboxyl terminus. Together these results suggest that the SH2 domain of p56lck has a dual function: (i) it can mediate intermolecular interactions with cellular proteins phosphorylated on tyrosine and thus might be involved in building up signaling complexes at the plasma membrane and (ii) it can bind to the tyrosine-phosphorylated carboxyl terminus of p56lck in an intramolecular fashion and thereby might be involved in the regulation of its intrinsic protein-tyrosine kinase activity. Phosphorylation/dephosphorylation of the regulatory tyrosine residue 505 might serve as a switch between these two functions.