9 research outputs found
Funktion der Transmembranproteine ESAM und JAM-A bei Zell-Zell-Interaktionen
No full text[no abstract
Nano-surgery at the leukocyte-endothelial docking site
No full textThe endothelium has an important role in controlling the extravasation of leukocytes from blood to tissues. Endothelial permeability for leukocytes is influenced by transmembrane proteins that control inter-endothelial adhesion, as well as steps of the leukocyte transmigration process. In a cascade consisting of leukocyte rolling, adhesion, firm adhesion, and diapedesis, a new step was recently introduced, the formation of a docking structure or "transmigratory cup." Both terms describe a structure formed by endothelial pseudopods embracing the leukocyte. It has been found associated with both para- and transcellular diapedesis. The aim of this study was to characterize the leukocyte-endothelial contact area in terms of morphology and cell mechanics to investigate how the endothelial cytoskeleton reorganizes to engulf the leukocyte. We used atomic force microscopy (AFM) to selectively remove the leukocyte and then analyze the underlying cell at this specific spot. Firmly attached leukocytes could be removed by AFM nanomanipulation. In few cases, this exposed 8-12 mum wide and 1 mum deep footprints, representing the cup-like docking structure. Some of them were located near endothelial cell junctions. The interaction area did not exhibit significant alterations neither morphologically nor mechanically as compared to the surrounding cell surface. In conclusion, the endothelial invagination is formed without a net depolymerization of f-actin, as endothelial softening at the site of adhesion does not seem to be involved. Moreover, there were no cases of phagocytotic engulfment, but instead the formation of a transmigratory channel could be observed
Zellsortierung mit einer geschlossenen, piezobasierten Sortiertechnologie
No full textSorting of cells is important for biomedical applications including cellular cloning steps or the isolation of rare variants. A new cell sorter combines a high performance with user comfort
Spectroscopic study of inclusions in gem corundum from Mercaderes, Cauca, Colombia
No full textMineral inclusions in gem corundum from Mercaderes, Cauca, Colombia, were investigated non-destructively using Raman and photoluminescence spectroscopy, with special focus lying on phases containing radioactive elements. Besides abundant rutile, the minerals zircon, apatite, feldspar, and an epidote-group species, most probably allanite–(Ce), were found. The latter is detected easily from its characteristic Nd3+ emission pattern, which may prove useful in future provenance studies. Zircon inclusions range from well crystalline to moderately radiation damaged [FWHM (full width at half band maximum) of the ν3(SiO4) Raman band 1.8–10.9 cm−1]. Both the zircon inclusions and their neighbouring host corundum are affected by compressive stress, which is assigned to (1) heterogeneous volume expansion of the host-inclusion couple upon pressure release during the uplift following primary growth and (2) volume expansion of the zircon inclusion due to the accumulation of self-irradiation damage. Internal stress of zircon inclusions averages ~1.1 GPa. Heat treatment of corundum leads to structural reconstitution of zircon (narrowed zircon Raman bands with FWHMs in the range 1.8–2.7 cm−1) and accompanying stress release in the adjacent corundum (indicated by downshifts of the R1 emission of Cr3+). The observation of broadened Raman band of zircon inclusions therefore allows one to exclude high-temperature enhancement of the host corundum.© The Author(s) 201
ESAM supports neutrophil extravasation, activation of Rho, and VEGF-induced vascular permeability.
No full textEndothelial cell-selective adhesion molecule (ESAM) is specifically expressed at endothelial tight junctions and on platelets. To test whether ESAM is involved in leukocyte extravasation, we have generated mice carrying a disrupted ESAM gene and analyzed them in three different inflammation models. We found that recruitment of lymphocytes into inflamed skin was unaffected by the gene disruption. However, the migration of neutrophils into chemically inflamed peritoneum was inhibited by 70% at 2 h after stimulation, recovering at later time points. Analyzing neutrophil extravasation directly by intravital microscopy in the cremaster muscle revealed that leukocyte extravasation was reduced (50%) in ESAM(-/-) mice without affecting leukocyte rolling and adhesion. Depletion of >98% of circulating platelets did not abolish the ESAM deficiency-related inhibitory effect on neutrophil extravasation, indicating that it is only ESAM at endothelial tight junctions that is relevant for the extravasation process. Knocking down ESAM expression in endothelial cells resulted in reduced levels of activated Rho, a GTPase implicated in the destabilization of tight junctions. Indeed, vascular permeability stimulated by vascular endothelial growth factor was reduced in ESAM(-/-) mice. Collectively, ESAM at endothelial tight junctions participates in the migration of neutrophils through the vessel wall, possibly by influencing endothelial cell contacts
Cyt‐Geist:Current and Future Challenges in Cytometry: Reports of the CYTO 2019 Conference Workshops
No full textThe need for cytometry instrumentation, reagents, training and scientific collaborations in the nations of Africa remains high despite strong efforts by both the African and foreign biomedical and cytometry research communities. Dr. Tesfa and Dr. Blanco therefore organized the first Cytometry in Africa Workshop at CYTO2019. This workshop had several goals. The first goal was to present the results of a pre-workshop survey aimed at assessing flow cytometry resources, personnel, experience and training in Africa. The results of this survey demonstrated important strengths in the African cytometry community, but also pinpointed areas where instrument access, reagent availability and training could be improved. The second goal was to present several collaborative scientific projects in Africa with participation by ISAC members. Third, both existing and proposed strategies for improving collaborative efforts and research support were presented, including cytometer donations, research collaborations and training programs. Finally, an open roundtable discussion was held with workshop attendees, many with experience in working in Africa. A diverse array of investigators from government, academia and industry attended and contributed to the workshop. A key outcome of the workshop was the establishment an African Working group in collaboration with the ISAC Instruments 4 Science Task Force, the ISAC Live Education Task Force, and the ISAC Education Committee. The workshop also marked the establishment of I4S, with the goal of advancing flow cytometry in the international research communit
