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Cell migration is an essential characteristic of life. However, the indispensable, physiological migration of embryonic and adult stem cells, leukocytes, and fibroblasts is opposed to the pathological migration of tumor cells during metastasis formation. Leukemic cells take a special position, since they combine characteristics of leukocyte and tumor cell migration. Although migration occurs in many variants with regard to dynamics and molecular mechanisms, myosin is generally needed to generate locomotory forces in all of the aformentioned cells. Our work aims to the understanding on the involvement of different myosin isotypes in the migration of leukocytes and leukemic cells at various stages of differentiation. By means of our three-dimensional, collagen-based migration assay, we investigated the involvement of nonmuscle myosin II and myosin VI in the migration of adult CD133 hematopoietic stem/progenitor cells (HSPCs) as well as of four leukemic cell lines (Jurkat, Molt-4, NB-4, Dohh-2) and cells from leukemia patients. We show that the spontaneous, matrix-induced migration of CD133 HSPCs solely depends on the activity of myosin VI, whereas the stromal cellderived factor (SDF)-1-induced migration requires both myosin isotypes. In contrast, leukemic cells engage both myosin isotypes for the spontaneous and the SDF-1-induced migration with varying proportions. Our previous studies have shown that the migration of differentiated leukocytes is exclusively based on non-muscle myosin II. We conclude that the proportionate involvement of non-muscle myosin II and myosin VI varies due to the differentiation state of the cells. The involvement of myosin VI decreases with the grade of differentiation, whereas the role of non-muscle myosin II increases.

AbstractThe aim of this study was to investigate an electrochemical process for bulk disinfection of biologically treated sewage. The influence of operating conditions (current density and flow rate) on the electrochemical formation of free chlorine in the sewage was determined. Furthermore, the effect of wastewater-specific parameters on the inactivation of Escherichia coliwas studied. The disinfection capacity is primarily influenced by the concentration of electrochemically produced free chlorine. The production rate of free chlorine is independent of the flow rate within the range of 25–125 L h−1. The investigations have also shown that the electrochemical disinfection of E. coliin secondary effluents with BDD electrodes proceeds effectively at an electric charge input of 0.1–0.15 Ah L−1corresponding to an energy expenditure of 2.0–2.6 kWh m−3. The electrochemically generated concentration of free chlorine (c = 0.4–0.6 mg L−1) is sufficient for an E. colireduction of four log levels under the following conditions: after-reaction time of 15–20 min, T > 6°C, pH < 8.5 and DOC < 22 mg L−1. The formation of organic by-products (AOX, THMs) was marginal to moderate. The inorganic by-products chlorate (1.2 mg L−l) and perchlorate (18 mg L−1) were produced in considerable concentrations.

The aim of this study was to investigate an electrochemical process for bulk disinfection of biologically treated sewage. The influence of operating conditions (current density and flow rate) on the electrochemical formation of free chlorine in the sewage was determined. Furthermore, the effect of wastewater-specific parameters on the inactivation of Escherichia coliwas studied. The disinfection capacity is primarily influenced by the concentration of electrochemically produced free chlorine. The production rate of free chlorine is independent of the flow rate within the range of 25–125 L h-1. The investigations have also shown that the electrochemical disinfection of E. coliin secondary effluents with BDD electrodes proceeds effectively at an electric charge input of 0.1–0.15 Ah L-1corresponding to an energy expenditure of 2.0–2.6 kWh m-3. The electrochemically generated concentration of free chlorine (c = 0.4–0.6 mg L-1) is sufficient for an E. colireduction of four log levels under the following conditions: after-reaction time of 15–20 min, T > 6°C, pH < 8.5 and DOC < 22 mg L-1. The formation of organic by-products (AOX, THMs) was marginal to moderate. The inorganic by-products chlorate (1.2 mg L-l) and perchlorate (18 mg L-1) were produced in considerable concentrations.

Carcinogenesis is a multistep process that is frequently associated with p53 inactivation. The class 1 carcinogen cadmium (Cd2+) causes renal cancer and is known to inactivate p53. G2/mitosis (M) arrest contributes to stabilization of p53-deficient mutated cells, but its role and regulation in Cd2+-exposed p53-deficient renal cells are unknown. In p53-inactivated kidney proximal tubule (PT) cells, comet assay experiments showed that Cd2+(50–100 μM) induced DNA damage within 1–6 h. This was associated with peak formation of reactive oxygen species (ROS) at 1–3 h, measured with dihydrorhodamine 123, and G2/M cell cycle arrest at 6 h, which were abolished by the antioxidant α-tocopherol (100 μM). Cd2+-induced G2/M arrest was enhanced approximately twofold on release from cell synchronization (double thymidine block or nocodazole) and resulted in approximately twofold increase of apoptosis, indicating that G2/M arrest mirrors DNA damage and toxicity. The Chk1/2 kinase inhibitor UCN-01 (0.3 μM), which relieves G2/M transition block, abolished Cd2+-induced G2arrest and increased apoptosis. This was accompanied by prevention of Cd2+-induced cyclin-dependent kinase cdc2 phosphorylation at tyrosine 15, as shown by immunofluorescence microscopy and immunoblotting. The data indicate that in p53-inactivated PT cells Cd2+-induced ROS formation and DNA damage trigger signaling of checkpoint activating kinases ataxia telangiectasia-mutated kinase (ATM) and ataxia telangiectasia and Rad3-related kinase (ATR) to cause G2/M arrest. This may promote survival of premalignant PT cells and Cd2+carcinogenesis.

Migration is an innate and fundamental cellular function that enables hematopoietic stem cells (HSCs) and endothelial progenitors (EPCs) to leave the bone marrow, relocate to distant tissue, and to return to the bone marrow. An increasing number of studies demonstrate the widening scope of the therapeutic potential of both HSCs and endothelial cells. Therapeutic success however not only relies upon their ability to repair damaged tissue, but is also fundamentally dependent on the migration to these areas. Extensive in vivo and in vitro research efforts have shown that the most significant effects seen on HSC migration are initiated by the chemokine SDF-1. In this review we will elucidate the many cellular and systemic factors of HSC and EPC cell migration and their modi operandi.

PTP-BL is a highly modular protein tyrosine phosphatase of unknown function. It consists of an N-terminal FERM domain, five PDZ domains, and a C-terminally located tyrosine phosphatase domain. Here we show that PTP-BL is involved in the regulation of cytokinesis. We demonstrate localization of endogenous PTP-BL at the centrosomes during inter- and metaphase and at the spindle midzone during anaphase. Finally PTP-BL is concentrated at the midbody in cytokinesis. We show that PTP-BL is targeted to the midbody and centrosome by a specific splicing variant of the N-terminus characterized by an insertion of 182 amino acids. Moreover, we demonstrate that the FERM domain of PTP-BL is associated with the contractile ring and can be cosedimented with filamentous actin, whereas the N-terminus can be cosedimented with microtubules. We demonstrate that elevating the expression level of wild-type PTP-BL or expression of PTP-BL with an inactive tyrosine phosphatase domain leads to defects in cytokinesis and to the generation of multinucleate cells. We suggest that PTP-BL plays a role in the regulation of cytokinesis.

Induction of tumor cell migration is a key step in invasion and metastasis. Here we report that the epidermal growth factor (EGF)‐induced cell migration of breast cancer cells is attributed to a transient, rather than a sustained, activation of phospholipase C (PLC) ‐γ1 due to c‐erbB‐2 signaling. EGF stimulation of EGF receptor (EGFR) overexpressing cells resulted in long‐term PLC‐γ1 tyrosine phosphorylation and sustained levels of inositol‐1,4,5‐triphosphate (IP3) and diacylglycerol (DAG) producing sinusoidal calcium oscillations. In contrast, c‐erbB‐2/EGFR expressing cells displayed baseline transient calcium oscillations after EGF treatment due to short‐term PLC‐γ1 tyrosine phosphorylation and short‐term IP3and DAG turnover. A third cell line expressing a point‐mutated c‐erbB‐2 receptor that lacks the autophosphorylation Y1248 was generated to investigate whether the different PLC‐γ1 activation was attributed to this structure. Neither PLC‐γ1 tyrosine phosphorylation nor IP3and DAG turnover and calcium oscillations were observed in this cell line, indicating the modulation of the PLC‐γ1 activation time course by c‐erbB‐2 signaling. Induction of cell migration was solely observable in the c‐erbB‐2‐positive cell line as proved by the mode of actin reorganization and a cell migration assay, using a 3D‐ collagen lattice. In summary, c‐erbB‐2 up‐regulation switches on the cell migration program by modulating the time course of PLC‐γ1 activation.

Separate mechanisms for oncogenesis and metastasis have been postulated. We show here that prolonged and invasive cell migration, a key mechanism in cancer metastasis, is linked to c‐erbB‐2 signaling. Cell lines with c‐erbB‐2 and EGFR expression and transphosphorylation activity display a high transendothelial invasiveness in an endothelial‐extra‐cellular matrix model mimicking a capillary vessel wall in vitro. Tyrosine‐phosphorylated c‐erbB‐2 receptors and EGFR are localized predominantly in areas of the cell with high membrane extension activity. On the molecular level, there is a subtle cross talk between the transmembrane signaling molecule c‐erbB‐2 and the actin cytoskeleton at multiple levels, including the generation of the second messenger PIP2 and the mobilization of the actin‐regulatory protein gelsolin. Our data strongly suggest that c‐erbB‐2, especially in a heterodimer with EGFR, is closely involved in signaling pathways, inducing alterations in cell morphology that are required for a human breast cancer cell to become motile and conceivably metastatic.—Brandt, B. H., Roetger, A., Dittmar, T., Nikolai, G., Seeling, M., Merschjann, A., Nofer, J.‐R., Dehmer‐Möller, G., Junker, R., Assmann, G., Zaenker. K. S. c‐erbB‐2/EGFR as dominant heterodimerization partners determine a motogenic phenotype in human breast cancer cells. FASEB J. 13, 1939–1949 (1999)

Overexpression of the c-erbB-2 gene-encoded p185c–erbB-2is correlated with early onset of metastasis in breast cancer patients. Furthermore, the detection of blood-borne epithelium-derived clustered cells expressing p185c–erbB-2was related to advanced stages in breast cancer. To further elucidate the receptor's function in the metastatic process of human breast cancers, we analyzed disaggregated cells and cell clusters from freshly dissected breast cancer tissues. We studied whether their capability of extravasation is correlated with their expression of c-erbB-2. A model for the venular wall was constructed by growing human umbilical vein endothelial cells (HUVECs) on porous membranes coated with basement membrane extracellular matrix. In four control breast cancer cell lines (SK-BR-3, MCF-7, MDA-MB-468, and MDA-MB-468, the latter transfected with a full-length c-erbB-2 cDNA vector) producing different levels of the c-erbB-2 receptor, the expression level correlated positively with the invasiveness of the cells. The invasive, predominantly clustered cells from 14 of 23 tumors were positively stained for p185c–erbB-2by immunocytochemistry. Furthermore, we show that the invasive cell populations express the metastasis-associated proteins matrix metalloproteinase MMP-2, CD44, and integrins αvβ3 and α6. In this first study on the behavior of cells and cell clusters from disaggregated operated cancers in an extravasation model, we could demonstrate the presence of c-erbB-2-expressing cell subpopulations within the individual breast cancers that are presumably of high metastatic potential.

Um das Risikopotential eines Kreditengagements zu kalkulieren, muß sich ein Kreditgeber im Rahmen der sogenannten Bonitätsprüfung unter anderem auch einen gründlichen Einblick in die wirtschaftliche Situation des zukünftigen Kreditnehmers verschaffen. Ein Verfahren, das in jüngerer Zeit in diesem Bereich zunehmend an Bedeutung gewonnen hat, ist das Instrument der Künstlichen Neuronalen Netze. Deren grundlegende Aspekte werden in diesem Beitrag dargestellt. Die Verfasser würdigen kritisch die wichtigsten Studien zur Bonitätsprüfung und erarbeiten Vorschläge zur Erstellung adäquater Künstlicher Neuronaler Netze (KNN).

Dimethylaminobis(trifluoromethyl)borane, (CF3)2BNMe2 (A), reacts with Grignard reagents RMgBr to yield, after hydrolysis, the dimethylamine boranes R(CF3)2B NHMe2 (R = Me (I), Et(II),iPr(III), -CH2CH=CH2 (IV), Ph (V),pTol (VI),oTol (VII),pClC6H4 (VIII) and −CCH (IX)). Alkylnytrimethylstannanes Me3SnCCR (R = Ph,nBu) add toA across the BN double bond and yield (RCC)(CF3)2B·NMe2SnMe3, the hydrolysis of which gives (PhCC)(CF3)2B·NHMe2 (X) and (nBuCC)(CF3)2B·NHMe2 (XI) respectively. In contrast, mesitylmagnesiumbromide reacts withA to yield (CF3)(Mes)FBFCNMe2 (XII), hydrolysis of which furnishes (CF3)(Mes)FBC(O)NHMe2 (XIII). Of the phosphorus ylids, only Ph3PCH2 and Ph3PCHCH3 react withA to give the respective adducts Ph3PCH2(CF3)2BNMe2 (XIV) and Ph3PCH(CH3)(CF3)2BNMe2 (XV). CF3SO3CH3 alkylatesXIV at the nitrogen atom to form [Ph3PCH2(CF3)2BNMe3]+[CF3SO3]− (XVI). The crystal and molecular structures ofXII andXIV have been determined by X-ray methods.