The anaesthetic propofol interacts with the GABAA receptor, but its cellular signalling pathways are not fully understood. Propofol causes reorganisation of the actin cytoskeleton into ring structures in neurons. Is this reorganisation a specific effect of propofol as apposed to GABA, and which cellular pathways are involved? We used fluorescence-marked actin in cultured rat neurons to evaluate the percentage of actin rings caused by propofol or GABA in combination with rho, rho kinase (ROK), PI3-kinase or tyrosine kinase inhibitors, with or without the presence of extracellular calcium. Confocal microscopy was performed on propofol-stimulated cells and changes in actin between cellular compartments were studied with Western blot. Propofol (3 μg·ml-1), but not GABA (5 μM), caused transcellular actin ring formation, that was dependent on influx of extracellular calcium and blocked by rho, ROK, PI3-kinase or tyrosine kinase inhibitors. Propofol uses rho/ROK to translocate actin from the cytoskeleton to the membrane and its actin ring formation is dependent on an interaction site close to the GABA site on the GABAA receptor. GABA does not cause actin rings, implying that this is a specific effect of propofol.

The protective immune response against the parasite, including the role of dendritic cells (DC) in the course of infection, plays a fundamental role. This study shows that wild-type (WT) Leishmania promastigotes and specifically the phosphoglycans family of virulence-associated antigens inhibit human monocyte-derived dendritic cells (MoDC) maturation and detachment to distinct surfaces. Immature phagocytosis of Leishmania donovani promastigotes by immature MoDC results in the increased expression of CD11b and CD51, and inhibition of cell detachment to distinct surfaces, which was dependent on the presence of phosphoglycans. These findings demonstrate that phosphoglycans of WT L. donovani might also inhibit human DC migration to lymphoid organs. © 2007 Federation of European Microbiological Societies.

Melanophores are pigment cells found in the skin of lower vertebrates. The brownish-black pigment melanin is stored in organelles called melanosomes. In response to different stimuli, the cells can redistribute the melanosomes, and thereby change colour. During melanosome aggregation, a height increase has been observed in fish and frog melanophores across the cell centre. The mechanism by which the cell increases its height is unknown. Changes in cell shape can alter the electrical properties of the cell, and thereby be detected in impedance measurements. We have in earlier studies of Xenopus laevis melanophores shown that pigment aggregation can be revealed as impedance changes, and therefore we were interested in investigating the height changes associated with pigment aggregation further. Accordingly, we quantified the changes in cell height by performing vertical sectioning with confocal microscopy. In analogy with theories explaining the leading edge of migrating cells, we investigated the possibility that the elevation of plasma membrane is caused by local swelling due to influx of water through HgC1₂-sensitive aquaporins. We also measured the height of the microtubule structures to assess whether they are involved in the height increase. Our results show that pigment aggregation in X. laevis melanophores resulted in a significant height increase, which was substantially larger when aggregation was induced by latrunculin than with melatonin. Moreover, the elevation of the plasma membrane did not correlate with influx of water through aquaporins or formation of new microtubules, Rather, the accumulation of granules seemed to drive the change in cell height.

This is a consensus document compiled by the Medical Products Agency in Sweden and the Swedish Reference Group for Antiviral Therapy on management of respiratory syncytial virus (RSV) infections. Prophylaxis against RSV infections using palivizumab, a commercially available humanized monoclonal IgG, antibody preparation, is recommended for children <2 y of age with chronic respiratory diseases requiring continuous treatment (oxygen and/or inhalations and/or steroids) during the previous 6 months and children 6 months old who were born before gestational week 26. Ribavirin inhalation treatment may be considered in high-risk infants with clinical symptoms indicating a serious course of an RSV infection. Treatment with ribavirin in combination with intravenous polyclonal immunoglobulin should be considered in patients who have received an allogenic stem cell transplantation or organ transplantation with >1 episode of rejection treatment and who have mild or moderate RSV pneumonia. Evidence-based documentation for treatment of other groups of patients is lacking.

The insulin receptor is a transmembrane protein of the plasma membrane, where it recognizes extracellular insulin and transmits signals into the cellular signaling network. We report that insulin receptors are localized and signal in caveolae microdomains of adipocyte plasma membrane. Immunogold electron microscopy and immunofluorescence microscopy show that insulin receptors are restricted to caveolae and are colocalized with caveolin over the plasma membrane. Insulin receptor was enriched in a caveolae-enriched fraction of plasma membrane. By extraction with β-cyclodextrin or destruction with cholesterol oxidase, cholesterol reduction attenuated insulin receptor signaling to protein phosphorylation or glucose transport. Insulin signaling was regained by spontaneous recovery or by exogenous replenishment of cholesterol. β-Cyclodextrin treatment caused a nearly complete annihilation of caveolae invaginations as examined by electron microscopy. This suggests that the receptor is dependent on the caveolae environment for signaling. Insulin stimulation of cells prior to isolation of caveolae or insulin stimulation of the isolated caveolae fraction increased tyrosine phosphorylation of the insulin receptor in caveolae, demonstrating that insulin receptors in caveolae are functional. Our results indicate that insulin receptors are localized to caveolae in the plasma membrane of adipocytes, are signaling in caveolae, and are dependent on caveolae for signaling.

Background: Propofol is known to interact with the γ-aminobutyric acidA (GABA_A) receptor, however, activating the receptor alone is not sufficient for producing anaesthesia. Propofol tyresine phosphorylates the GABAA receptor and reorganises the actin cytoskeleton, eausing ring structures and rnembrane ruffles. Propofol, but not GABA, the endogenous tigand for the GABAA receptor, tyresine phosphorylates actin, both in the membrane and cytoskeletal fractions of the neuron.

Aim: How does propofol cause the actin reorganisation and is this a specific effect of propofol? Is the small membrane associated G-protein rho involved in the signal cascade towards the actin reorganisation?

Methods: Westem blotting (WB) was used to visualize tyresine phosphorylated immunoprecipitated proteins and changes in actin between the different cellularcompartments after inhibition with rho (C₃ exotoxin) and rho kinase (ROK) (HA-1077) inhibitors. Fluoreseenee mireoscopy after rhodamine-phalloidin labelling of actin was used to calculate the number of actin ring structures caused by propofol or GABA, in same experiments combined with pre-incubation with C₃ exotoxin, HA- 1077 or the tyrosine kinase inhibitor Herbimycin A. Propofol-stimulated cells were studied with confocal microscopy.

Results: Propofol eaused an increased tyresine phosphorylation, that was reduced by C₃ exotoxin, of a 160 kDa protein after two minutes stimulation. The 160 kDa protein is still unidentified. The actin ring structures caused by propofol was shown with confocal microscopy to go almost through the entire cell. The amount of rings were reduced by C3 exatoxin as well as HA-1077. Furthermore, w hen a tyrosine kinase bioeker was used no ring structures were formed. However, GABA did not produce any ring structures. When the actin content of the cellular campartments were analysed, C3 exatoxin treated cells showed an increased amount of actin in the cytoskeletal fraction, simultaneausly with a decrease in both the membrane and the cytosol fractions. The ROK bioeker on ly eaused a reduction of actin in the cytosol/membrane fractions, but no increase was observed in the cytoskeleton.

Conclusion: Propofol, but not GABA, eauses actin ring structures in neurons. Propofol uses the rho and rho kinase pathway to reorganize the actin cytoskeleton into ring structures, which is also dependent on a tyresine klnase. Propofol also eauses an unidentified rho dependent 160 kDa protein to be tyresine phosphorylated. The activation eaused by propofol of rho and rho kinase causes actin to be moved from the cytoskeleton to the cell membrane and cytosol. This reorganisation of actin might influence the GABA_A receptor by keeping it open, thus allowing the cell to be hyperpolarized for longer time, and consequently maintain anaesthesia.