Rasosomes originate from the Golgi to dispense Ras signals.

Ras proteins undergo an incompletely understood trafficking process in the cell. Rasosomes are protein nanoparticles of 80-100 nm diameter that carry lipidated Ras isoforms (H-Ras and N-Ras) as well as their effectors through the cytoplasm and near the plasma membrane (PM). In this study, we identified the subcellular origin of rasosomes and how they spread Ras proteins through the cell. We found no dependency of rasosome formation on galectins, or on the GDP-/GTP-bound state of Ras. We found that significantly more rasosomes are associated with forms of Ras that are localized to the Golgi, namely N-Ras or the singly palmitoylated H-Ras mutant (C181S). To explore the possibility that rasosome originate from the Golgi, we used photoactivatable (PA)-GFP-H-Ras mutants and showed that rasosomes bud from the Golgi in a two-step mechanism. Newly released rasosomes first move in an energy-dependent directed fashion and then convert to randomly diffusing rasosomes. Dual fluorescence time-lapse imaging revealed the appearance of dually labeled rasosomes, indicating a dynamic exchange of cytoplasmic and PM-associated Ras with rasosome-associated Ras. Finally, higher levels of rasosomes correlate with higher levels of ERK phosphorylation, a key marker of Ras downstream signaling. We suggest that H-Ras and N-Ras proteins exchange with rasosomes that can function as carriers of palmitoylated Ras and its signals.

High dose intravenous immunoglobulin (IVIG) in dermatomyositis: clinical responses and effect on sIL-2R levels.

An open study was conducted to identify and investigate dermatomyositis patients who benefit from IVIG treatment, based on dermatological criteria, myositis-related symptoms and immune/inflammatory parameters. 19 patients (16 females and three males, ages 31-84) suffered from dermatomyositis, and 4/19 patients had paraneoplastic dermatomyositis. We monitored the disease activity by documenting the clinical symptoms, recording muscle-related parameters (electromyography, serum creatine kinase, histopathology), and by determining circulating autoantibodies and serum levels of IL-6, sIL-2R, sTNF-a-R, sICAM-1, and sCD8. 7/19 patients responded to IVIG. They had severe skin but only moderate muscle involvement, no autoantibodies, and no malignancy. IVIG-nonresponders had severe skin and muscle disease, concomitant with autoantibodies and/or malignancy. sIL-2R levels were initially elevated in all patients but reverted to normal in IVIG-responders only. Creatine kinase-levels and other parameters did not correlate with disease activity and/or treatment response. IVIG is effective in selected dermatomyositis patients. sIL-2R serum levels appear to be useful predictors of IVIG-induced treatment response and disease activity.

[Established and new therapeutic approaches in dermatomyositis, polymyositis and overlapping syndromes]. / Etablierte und neue Therapiestrategien bei Dermatomyositis, Polymyositis und Uberlappungssyndromen.

An overview is presented on current antiinflammatory, cytostatic/cytotoxic and immunomodulatory treatments for immunologically mediated inflammatory myopathies with skin involvement. High-dose intravenous immunoglobulin (IVIG) therapy is discussed in the context of recent findings regarding pathogenic mechanisms of autoimmune diseases.

[The value of thoracic and abdominal computed tomography with intensive care patients]. / Wertigkeit der thorakalen und abdominellen Computertomographie bei Intensivpatienten.

We evaluated in a retrospective study the therapeutic relevance of thoracic and abdominal CT examinations on 157 intensive-care patients with previously inconclusive radiological examinations. Indications for CT were sepsis (n = 105), rarely a decrease in haematocrit (n = 30), multiorgan failure (n = 16) or suspected aortic aneurysm (n = 6). In 83.4% of examinations CT detected clinically relevant features, in 44.3% positive CT studies resulted in invasive therapy within 72 hours and therefore changed patient management decisively. Our results justify the use of CT, enabling if necessary an on-target intervention, the advantages outweighing the inherent risks if the patient is exposed to the relatively small risk of being temporarily removed from the intensive-care unit for immediate invasive treatment.

Size heterogeneity of human lymphotoxin is due to O-linked glycosylation.

Lymphotoxin (LT), a cytokine with antiviral and antitumor activities, is produced by activated T- and B-lymphocytes. The molecular weight (MW) of this glycoprotein has been reported to be 24 and 25 kDa for the mature molecule and 18.6 kDa for the recombinant form. Here we report that various human T- and B-cell lines as well as freshly stimulated T and B cells release LT molecules of different sizes, ranging from 23 to 27 kDa by SDS polyacrylamide gele electrophoresis (PAGE) analysis. Although individual cell lines produce LT of characteristic size, no firm association between the different MW forms with either the B or the T cell lineage could be established. The size heterogeneity of LT is due to O-linked glycosylation since only the removal of both N- and O-linked sugar residues but not removal of N-linked sugar residues alone, reduces the size of all forms to around 18.6 kDa, which corresponds to the calculated MW of the recombinant form of human LT.

[Weaning using continuous-flow CPAP: hemodynamics and gas exchange]. / Weaning mit continuous-flow CPAP: Hämodynamik und Gasaustausch.

The present study was designed to investigate hemodynamics and gas exchange during weaning from mechanical ventilation (assist/control mode) to spontaneous breathing with continuous high flow (chf)-CPAP, and to study the predictive value of these parameters in respect of longterm success or failure of weaning. Hemodynamic and gas exchange parameters were obtained in 10 patients without severe pulmonary and cerebral dysfunction at -240, -60, -30, and -15 min before, and at +15, +30, +45, +60, +120, +180, +240 min after chf-CPAP. During chf-CPAP significant increases in heart rate/min (92 +/- 17 to 103 +/- 20), cardiac index (3.9 +/- 0.7 to 4.4 +/- 1.0 1/min.m2), respiratory rate/min (15 +/- 1 to 28 +/- 7), PaCO2 (36.7 +/- 3.0 to 41.2 +/- 5.9 torr) and oxygen delivery (12.2 +/- 2.7 to 13.9 +/- 2.3 ml/min.kg) were found. Arterial and pulmonary artery pressures rose only briefly within the first hour. All other parameters changed non-significantly. In the 4 patients who required mechanical ventilation 12 to 34 hours after the end of the study we found a significantly more pronounced increase in heart rate than in those who where weaned successfully (114 +/- 19 vs 89 +/- 9). Increases in heart rate, respiratory rate, cardiac index, PaCO2 and oxygen delivery can therefore be expected during weaning from mechanical ventilation to spontaneous breathing with CPAP. A pronounced increase in heart rate may suggest a weaning failure.