J. Knizek

Differences in Vanadocene Dichloride and Cisplatin Effect on MOLT-4 Leukemia and Human Peripheral Blood Mononuclear Cells

Modern chemotherapy is interested in developing new agents with high efficiency of treatment in low-dose medication strategies, lower side toxicity and stronger specificity to the tumor cells. Vanadocene dichloride (VDC) belongs to the group of the most promising metallocene antitumor agents; however, its mechanism of action and cytotoxicity profile are not fully understood. In this paper we assess cytotoxic effects of VDC in comparison to cisplatin using opposite prototype of cells; human peripheral blood mononuclear (PBMCs) cells and human acute lymphoblastic leukemia cell line (MOLT-4). Our findings showed cytotoxic effect of VDC on leukemia cells, but unfortunately on human peripheral blood mononuclear cells as well. VDC induces apoptosis in leukemia cells; the induction is, however, lower than that of cisplatin, and in contrary to cisplatin, VDC does not induce p53 up-regulation. Cytotoxic effect of VDC on leukemia cells is less pronounced than that of cisplatin and more pronounced in PBMCs than in MOLT-4 cells.

The usage of contextual discounting and opposition in determining the trustfulness of users in online auctions

The communication within Internet auction systems proceeds as a rule under the situation in which users are not in physical contact nor they do not know anything of each other. They have therefore to rely on reputation mechanisms implemented within these online systems. Such mechanisms help to create a trustworthy environment on the basis of additional attributes associated with users and their roles. The trustworthy environment in online auction systems (trust of the system itself and trust among users of this virtual world) is the essential element for these systems functioning. This paper introduces a trust model based on reputation while it takes into account possible fraudulent behavior of users in online auctions as contextual information. The reputation is calculated from users evaluations (feedback) following performed transactions. Information about possible fraudulent behavior is additional information determining the reliability of the users reputation in our trust model. Reputation and fraudulent behavior are expressed in a form of belief functions and the resulting users trustfulness is calculated. The case study shows that the proposed approach is valid and may be applicable in real online auctions.

Evaluation of Skin Microcirculation during Hemodialysis

Background. Cardiovascular mortality in hemodialysis (HD) patients remains high despite improvements in HD technique such as dialysis adequacy, dialysis fluid purity, and membrane biocompatibility. Optimal fluid balance to maintain optimal hemodynamic stability during hemodialysis (HD) procedure is essential. At the present time, hemodynamic stability is conventionally assessed as stability of macrocirculation, especially as maintenance of systemic blood pressure with no attention paid to peripheral perfusion. Peripheral ischemic vascular disease represents a serious problem with high mortality and morbidity. We estimated skin microcirculation changes during HD using new device, Laser Doppler Line Scanner (Moor Instruments, Devon, UK). Aims. The aims were to introduce the novel method of detection of skin perfusion changes during hemodialysis and to evaluate possible relationship of these to ultrafiltration as well as to selected biochemical characteristics. Methods. In 36 hemodynamically stable patients, we performed paired measurements of skin blood flow in both hands before and during HD with registering the time of dialysis and the total ultrafiltration achieved. Results. We found a significant decrease in a majority of the evaluated areas. However, the skin blood flow change was not homogenous as it decreased more on the fingers. Conclusion. To our knowledge, this is the first study when the microcirculatory changes during hemodialysis are demonstrated and evaluated in large skin surface area, and showing not only a decrease in a majority of areas but also the heterogeneity of the changes.

Evaluation of the Antineoplastic Activity of L-rhamnose in vitro. A Comparison with 2-deoxyglucose

The effect of unsubstituted deoxyhexoses, 2-deoxy-D-glucose (2-DG) and L-fucose, on tumor cells has been reported in several papers throughout the last decades. That of a similar deoxysugar, L-rhamnose, which is synthesized in bacteria and plants but not in animal cells, has until today not been explored. In the present study, we examined the effect of L-rhamnose on DNA and protein synthesis, growth and the potential induction of apoptosis of tumor cells in vitro. Using 2-DG for comparison, we studied the effect of L-rhamnose in concentrations up to 20 (32 resp.) mmol/l on the initial velocity of the incorporation of labeled precursors of DNA and proteins in short term cultures of both mouse Ehrlich ascites tumor (EAT) and human HL-60 cells in vitro, and further, on cell proliferation and apoptosis induction in HL-60 cells. Neither cytotoxic nor cytostatic effects of L-rhamnose were observed with the exception of slightly pronounced inhibition of DNA synthesis in EAT cells. From the lacking inhibition of the protein synthesis it can be considered that L-rhamnose does not interfere with energy metabolism, at least not in a similar manner as 2-DG.