Neutrophil mobility during anaesthesia in children. A trial of ascorbate premedication

In 20 healthy children undergoing elective surgery, mobility of neutrophils, both unstimulated and stimulated by endotoxin, was studied using a millipore filter system with microscopic determination of leading front migration. Paired samples were incubated with 10(-2) mol l-1 calcium ascorbate and ten children also received 10 mg kg-1 ascorbic acid before premedication. Stimulation of mobility was reduced after the opioid premedication (P less than 0.05) in the ascorbate group only, but not significantly during anaesthesia and surgery. A few individuals showed persisting abnormally low values. No effect of ascorbate in vivo or in vitro was demonstrated. There were no infections.     

The chemotactic activity of T-lymphocytes in response to interleukin 8 is significantly decreased in patients with psoriasis and atopic dermatitis

Abstract Involvement of T-lymphocytes in the pathogenesis of psoriasis and atopic dermatitis is well established. The question arises as to whether not only tissue infiltrating but also circulating T-lymphocytes are involved in the disease process. Therefore we sought to determine whether T-lymphocytes from patients with psoriasis and atopic dermatitis show abnormal biological behavior to the proinflammatory chemokine interleukin 8 (IL-8) in vitro as studied by their chemotactic activity. In addition, the expression of T-cell activation markers such as HLA-DR and interleukin 2 receptor (IL-2R) were analysed with FACS-technique. In all, 25 patients with psoriasis (13 patients with severe psoriasis and 12 patients with mild psoriasis) and 11 patients with atopic dermatitis were investigated. For comparison, T-lymphocytes from 14 healthy controls were tested equally. The results show that T-cell chemotactic responses to IL-8 were significantly decreased in patients with severe psoriasis as compared to healthy controls. T-cells from patients with atopic dermatitis demonstrated an even more pronounced decrease in chemotactic response as compared to T-cells from psoriasis patients or healthy controls. In contrast, increased expression of activation markers HLA-DR and IL-2R were demonstrated in circulating T-cells from patients with severe psoriasis and atopic dermatitis in comparison to healthy controls. It can be concluded that circulating T-cells in patients with severe psoriasis and atopic dermatitis show a decreased in vitro chemotactic response to IL-8. Furthermore, the in vivo phenotypic activation state of T-lymphocytes in these patients seemed to be associated with their decreased in vitro functional capacity.     

Identifying the Relative Contributions of Rac1 and Rac2 to Osteoclastogenesis

Rac small GTPases may play an important regulatory role in osteoclastogenesis. Our in vitro and in vivo results show that both Rac1 and Rac2 are required for optimal osteoclast differentiation, but Rac1 is more critical. Rac1 is the key Rac isoform responsible for regulating ROS generation and the actin cytoskeleton during the multiple stages of osteoclast differentiation. Introduction: Recent evidence suggests that the Rac small GTPases may play an important regulatory role in osteoclastogenesis. This finding is important because bisphosphonates may regulate their antiresorptive/antiosteoclast effects through the modification of Rho family of small GTPases. Materials and Methods: To elucidate the specific roles of the Rac1 and Rac2 isoforms during osteoclastogenesis, we used mice deficient in Rac1, Rac2, or both Rac1 and Rac2 in monocyte/osteoclast precursors. Macrophage‐colony stimulating factor (M‐CSF)– and RANKL‐mediated osteoclastogenesis in vitro was studied by using bone marrow‐derived mononucleated preosteoclast precursors (MOPs). The expression of osteoclast‐specific markers was examined using quantitative real‐time PCR and Western blot analysis. Free actin barbed ends in bone marrow MOPs after M‐CSF stimulation was determined. The ability of MOPs to migrate toward M‐CSF was assayed using Boyden chambers. Margin spreading on heparin sulfate‐coated glass and RANKL‐induced reactive oxygen species generation were also performed. Functional assays of in vitro‐generated osteoclasts were ascertained using dentine sections from narwal tusks. Osteoclast levels in vivo were counted in TRACP and immunohistochemically stained distal tibial sections. In vivo microarchitexture of lumbar vertebrate was examined using μCT 3D imaging and analysis. Results: We show here that, although both Rac isoforms are required for normal osteoclast differentiation, Rac1 deletion results in a more profound reduction in osteoclast formation in vitro because of its regulatory role in pre‐osteoclast M‐CSF‐mediated chemotaxis and actin assembly and RANKL‐mediated reactive oxygen species generation. This Rac1 cellular defect also manifests at the tissue level with increased trabecular bone volume and trabeculae number compared with wildtype and Rac2‐null mice. This unique mouse model has shown for the first time that Rac1 and Rac2 play different and nonoverlapping roles during osteoclastogenesis and will be useful for identifying the key roles played by these two proteins during the multiple stages of osteoclast differentiation. Conclusions: Rac1 and Rac2 play different and nonoverlapping roles during osteoclastogenesis. This model showed that Rac1 is the key Rac isoform responsible for regulating ROS generation and the actin cytoskeleton during the multiple stages of osteoclast differentiation.     

In Vitro Effect of Terbinafine on Human Leukocyte Chemotaxis and Chemiluminescence/In vitro-Effekt von Terbinafin auf die Chemotaxis und Chemilumineszenz von Leukozyten des Menschen

Summary: The in vitro effect of terbinafine, a broad spectrum antifungal agent on human peripheral blood polymorphonuclear leucocyte (PMNL) functions was studied in comparison to the known inhibitor cytochalasin B (CYTB). At concentrations above and below therapeutically achieveable plasma levels, terbinafine had no effect on either viability, chemotaxis or chemiluminescence of PMNL whether following simultaneous addition of the drug or prior treatment of the PMNL cells with drug. CYTB caused a statistically significant decrease in motility and chemiluminescence response of PMNL. The present in vitro studies demonstrate no adverse immunotoxic effects of terbinafine on major neutrophil functions even at concentrations several-fold higher than those generally found in plasma of humans receiving oral treatment.
Zusammenfassung: Terbinafin, ein Breitband-Antimykotikum, wurde hinsichtlich seines in vitro-Effektes auf verschiedene Funktionen peripherer, polymorphkerniger Leukozyten (PMNL) des Menschen im Vergleich zu Cytochalasin B (CYTB), einem bekannten Hemmstoff, untersucht. Bei Konzentrationen, die hÖher bzw. niedriger waren als die thera- peutisch erreichbaren Plasmaspiegel, hatte Terbinafin unabhängig davon, ob die Substanz gleichzeitig zugegeben wurde oder ob die PMNL mit der Substanz vorbehandelt wurden, weder einen Effekt auf die Vitalität noch auf die Chemotaxis oder Chemilumineszenz von PMNL. CYTB führte zu einer statistisch signifikanten Abnahme der Motilität und Chemilumineszenz von PMNL. Die vorlie-genden In vitro-Untersuchungen zeigen, daß Terbinafin selbst bei Konzentrationen, welche urn ein Vielfaches hÖher waren als die üblicherweise im Plasma des Menschen nach oraler Therapie bestimmten, keinen immunotoxischen Effekt auf die wichtigsten Funktionen von Neutrophilen hat.