Doris Moser

The role of oxygen termination of nanocrystalline diamond on immobilisation of BMP-2 and subsequent bone formation

Medical implants are increasingly often inserted into bone of frail patients, who are advanced in years. Due to age, severe trauma or pathology-related bone changes, osseous healing at the implant site is frequently limited. We were able to demonstrate that coating of endosseous implants with nanocrystalline diamond (NCD) allows stable functionalization by means of physisorption with BMP-2. Strong physisorption was shown to be directly related to the unique properties of NCD, and BMP-2 in its active form interacted strongly when NCD was oxygen-terminated. The binding of the protein was monitored under physiological conditions by single molecule force spectroscopy, and the respective adsorption energies were further substantiated by force-field-calculations. Implant surfaces refined in such a manner yielded enhanced osseointegration in vivo, when inserted into sheep calvaria. Our results further suggest that this technical advancement can be readily applied in clinical therapies with regard to bone healing, since primary human mesenchymal stromal cells strongly activated the expression of osteogenic markers when being cultivated on NCD physisorbed with physiological amounts of BMP-2.

Sufentanil inhibits migration of human leukocytes through human endothelial cell monolayers.

The interactions between blood and vascular wall cells are essential for understanding pathophysiological processes, e.g., during inflammation. The influence of anesthetics on leukocyte function is well documented. An inhibitory effect of thiopental, midazolam, and ketamine on leukocyte chemotaxis in a Boyden chamber chemotaxis assay (i.e., endothelial cells were not included) has been demonstrated. Little is known, however, about the influence of sufentanil on the inflammatory processes. To reach their targets in the tissue in vivo, leukocytes must interact with endothelial cell monolayers (ECMs). The aim of the current study was to investigate the influence of sufentanil on the migration of leukocytes through an ECM. Human umbilical vein endothelial cells were cultured to achieve a monolayer. Isolated polymorphonuclear leukocytes and ECM were preincubated with different concentrations of sufentanil. The rate of leukocyte migration against the chemotactic protein formyl-methyl-leucyl-phenylalanine was measured (n = 7). Sufentanil significantly reduced the amount of leukocyte migration through ECM to 77% +/- 7.8% (P < 0.05 compared with control). Endothelial cells as well as leukocytes contributed to this effect: treatment of both cell types showed an additive effect. Although lower concentrations showed no effect, high concentrations reduced leukocyte migration through ECM to 61% +/- 7.1%. Implications: Leukocytes play an important role during inflammation, and anesthetics influence leukocyte functions, e.g., respiratory burst or chemotaxis. The effect of sufentanil on transendothelial leukocyte migration has not been investigated. Therefore, we used a migration assay including endothelial cell monolayers. Sufentanil showed a reducing effect on transendothelial leukocyte migration. (Anesth Analg 1998;87:1181-5)

Propofol reduces the migration of human leukocytes through endothelial cell monolayers

OBJECTIVEnTo test propofol and the solvent of propofol on leukocyte function in the presence of endothelial cell monolayers. The interactions of leukocytes with endothelial cells play a tremendous role during inflammation. Previous studies have investigated the influence of propofol on leukocytes.nnnDESIGNnProspective, controlled study.nnnSETTINGnUniversity research laboratories.nnnSUBJECTSnSeven independent experiments were performed to investigate the influence of propofol (0.4, 4, and 40 ng/mL) on the migration of human leukocytes through human endothelial cell monolayers. Moreover, the authors tested the solvent of propofol on leukocyte migration.nnnINTERVENTIONSnHuman endothelial cell monolayers and/or human leukocytes were preincubated with clinically relevant higher and lower concentrations of propofol. The amount of leukocyte migration after 3 hrs was measured with a fluorometer.nnnMEASUREMENTS AND MAIN RESULTSnHuman endothelial cells isolated from umbilical veins were cultured on microporous membranes until they formed an endothelial cell monolayer. Leukocytes were separated by standard procedures. The migration of leukocytes through monolayers of endothelial cells using the clinically relevant concentration of propofol was reduced to 93% +- 3.8% (so; p < .05) when the leukocytes but not the endothelial cell monolayers were preincubated with propofol. Leukocyte migration was reduced to 80% - 5.9% (p < .05) when only monolayers of endothelial cells were treated with propofol, and was reduced to 73% + 10.4% (p < .05) when both leukocytes and monolayers of endothelial cells were treated with propofol. The higher and lower concentrations showed a dose-dependent effect. The solvent of propofol had no significant effect.nnnCONCLUSIONnThe authors investigated the influence of propofol and its solvent on the interaction between both cell systems-leukocytes and endothelial cells. Propofol is able to reduce significantly the migration of leukocytes through endothelial cell monolayers. The use of different doses revealed a dose-dependent effect. The current model allowed treatment of one cell type: leukocyte or endothelial cell. The results of this investigation indicate that the influence of propofol on leukocyte migration affects endothelial cells more than leukocytes.

Hydroxyethyl starch reduces the chemotaxis of white cells through endothelial cell monolayers

BACKGROUND: Polymorphonuclear leukocytes (PMNs) play a tremendous role during inflammatory processes. PMNs have to pass a monolayer of endothelial cells to migrate into the extravascular space. Hydroxyethyl starch (HES) is frequently used as a volume expander in critically ill patients.

Ketamine significantly reduces the migration of leukocytes through endothelial cell monolayers

OBJECTIVEnTo study the role of neutrophils in host defense, using human endothelial cells in migration studies in the presence of ketamine (0.3, 3, and 30 microg/mL).nnnDESIGNnProspective, controlled study.nnnSETTINGnUniversity research laboratories.nnnSUBJECTSnSeven independent experiments from different donors were done, investigating the influence of ketamine (0.3, 3, and 30 microg/mL) to the migration of human leukocytes through human endothelial cell monolayers.nnnINTERVENTIONSnHuman endothelial cell monolayers and/or human leukocytes were preincubated with clinically relevant (3 microg/mL), higher (30 microg/mL), and lower (0.3 microg/mL) concentrations of ketamine. The amount of leukocyte migration after 3 hrs was measured in a fluorometer.nnnMEASUREMENTS AND MAIN RESULTSnHuman endothelial cells isolated from umbilical veins were cultured on microporous membranes (polyethylene-terephthalat membranes) until they formed an endothelial cell monolayer. Leukocytes were separated by standard procedures. The migration of leukocytes through monolayers of endothelial cells under the clinically relevant concentration of ketamine was reduced to 59+/-9.8% (SD) (p< .05) when leukocytes but not the endothelial cell monolayers were preincubated with ketamine. Leukocyte migration was reduced to 92+/-7.3% (p > .05) when only monolayers of endothelial cells were treated with ketamine, and to 52+/-8.8% (p< .05) when both leukocytes and monolayers of endothelial cells were treated with ketamine. The higher and lower concentrations showed a dose-dependent effect.nnnCONCLUSIONSnWe investigated the cellular interaction between both cell systems, leukocytes and endothelial cells, simultaneously in the presence of ketamine. Ketamine is able to reduce significantly the migration of leukocytes through endothelial cell monolayers. The use of different dosages revealed a dose-dependent effect. The current model allowed treatment of one cell type, either leukocyte or endothelial cell. Ketamine inhibits the function of leukocytes more than the function of endothelial cells.

Airway Management with Endotracheal Tube versus Combitube® during Parabolic Flights

Background: Training of National Aeronautics and Space Administration space shuttle astronauts revealed difficult airway management with endotracheal tubes (ETTs) under microgravity conditions. The authors performed a randomized comparative study of ETT and Combitube® (ETC; Tyco Healthcare, Pleasanton, CA). The aim of the study was to evaluate ease, time of insertion, and success rates during normogravity and parabolic flights using mannequins. Methods: After normogravity experiments, four flyers performed intubation on a mannequin during the flights. Sixty-two intubation attempts were performed using the ETC (normogravity, 29; microgravity, 33), and 58 intubation attempts were performed using the ETT (each 29 attempts, both conditions). Time to completion of the intubation procedure, success rate, and ease of insertion were recorded. Results: The ETC performed equally well between normogravity (median, 18 s; range, 17–25 s) and microgravity (median, 18.5 s; range, 17–28 s), whereas the ETT performed significantly slower under microgravity (median, 20 s; range, 17–27 s) as compared with normogravity (median, 18 s; range, 16–22 s; P = 0.019). One hundred nine of 120 (90%) were successful. The ETT and ETC were comparable with respect to successful intubations, under normogravity or microgravity, respectively. Conclusions: Both the ETC and ETT perform comparably well. Slight differences could be found with respect to time of insertion in favor of the ETC. Because this is the first experiment using the ETC on the KC-135, it is shown that there is enough time to perform the insertion procedure. Because the ETC airway requires less training and is easier to insert than an ETT, it is recommended for further study as an alternative airway to what is currently on the shuttle.

Thrombus formation on the balloon of heparin-bonded pulmonary artery catheters: an ultrastructural scanning electron microscope study.

Objective: To investigate heparin‐bonded pulmonary artery catheters with respect to thrombus formation and platelet aggregation at the balloon and the shaft using a scanning electron microscope in critically ill patients. Design: Prospective study. Settings: Critical care unit and research laboratories. Patients: Pulmonary artery catheters were inserted in critically ill patients (n = 10). Interventions: Pulmonary artery catheters were removed after 24, 48, 72, or 120 hrs, and the ultrastructure was investigated in specialized research laboratories. Measurements and Main Results: Balloon and shaft were investigated using a scanning electron microscopic technique. Area of thrombus formation was quantified using image analysis. Heparin release of the catheters was measured. The frequency of balloon inflations was investigated in in vitro experiments by inflating catheters different times (0, 10, 20, and 30 times). Twenty‐four hours after catheter insertion, scanning electron microscopic images showed thrombus formation and platelet aggregation at the site of the balloon. Seventy‐two hours after catheter insertion, a thrombus started to detach. The areas of thrombus formation did not differ, but thrombus organization changed dramatically 72 and 120 hrs after catheter insertion. The shaft was colonized by single cells only. Cracks of the balloon could be observed after 72 hrs, whereas no cracks could be found in in vitro controls. In vitro, heparin release of the pulmonary artery catheters decreased significantly after 24 hrs. Conclusions: Scanning electron microscopic images of heparin‐bonded pulmonary artery catheters demonstrate thrombus formation on the balloon 24 hrs after pulmonary artery catheter insertion, increasing dramatically at 72 and 120 hrs. The shaft was colonized by single cells only. The thrombus size is not significantly different during the observation time, but the grade and quality of thrombus formation differ.

Thiopental inhibits migration of human leukocytes through human endothelial cell monolayers in vitro

ObjectivesThe interactions between blood and vascular wall cells are essential for the understanding of pathophysiologic processes, e. g. inflammation. The influence of the anesthetic drug thiopental on leukocyte function is well documented. Recently, an inhibitory effect of thiopental on leukocyte chemotaxis in a Boyden chamber assay (i. e. endothelial cells were not included) was demonstrated. In vivo, leukocytes have to interact with endothelial cell monolayers to invade the tissue. The influence of thiopental on a monolayer of endothelial cells has not yet been investigated. The aim of the current study was to investigate the influence of thiopental on the migration of leukocytes through endothelial cell monolayers (ECM).Material and methodsHuman umbilical vein endothelial cells (HUVEC) were isolated and cultured on microporous membrane filters to achieve a monolayer. Isolated polymorphonuclear leukocytes (PMNL) as well as ECM were preincubated with different concentrations of thiopental. The rate of leukocyte migration against the chemotactic protein formyl-methyl-leucyl-phenyla-lanine was measured (n=7). Thiopental was able to reduce the amount of leukocyte migration through ECM significantly.ConclusionIn conclusion, we could show that thiopental is able to reduce the migration of PMNL through ECM significantly.

Leukocyte migration: A new triple migration chamber assay allows investigation of various cell interactions simultaneously

Abstract Examination of the interactions between various cells of the vascular wall and blood components are essential for understanding different pathophysiological processes. Such investigations require appropriate techniques. Several groups have attempted to establish different methods. In all blood vessels except capillaries, endothelial cells (EC) and smooth muscle cells (SMC) coexist and interact very closely. The current study describes a new 3-dimensional triple chamber migration assay, studying leukocyte migration through human endothelial cell monolayers (ECM) towards human SMC layers simultaneously. To test the new assay, SMC-layers were prestimulated with different concentrations of tumor necrosis factor alpha (TNF-α, 1 ng ml , 10 ng ml , 100 ng ml ) over 6 hours. Then, two microporous membranes, a collecting membrane and a third membrane with cultured ECM, were inserted. Freshly isolated peripheral blood mononuclear cells (PBMNC) were seeded on the ECM and transmigrated cells were measured after further 3 hours incubation. The migration against non stimulated SMC-layers was used as control. Prestimulated SMC-layers led to a dose dependent increase of PBMNC migration into the subendothelial cell space. Antibodies against interleukin-1 reduced the PBMNC migration. In conclusion, this assay allows to study cell migration into the subendothelial space and interactions between different vascular cells. Moreover, this assay can also be used for studies on other cell-cell interactions in man.

A scanning electron microscopic study on thrombogenicity of intraarterial catheters for chemotherapeutic treatment in head and neck cancer

The purpose of this study was to assess the impact of standard anticoagulation and intermittent catheter irrigation on clot formation on intraarterial chemotherapeutical catheters.