Recording and assessment of evoked potentials with electrode arrays.

In order to optimize procedure for the assessment of evoked potentials and to provide visualization of the flow of action potentials along the motor systems, we introduced array electrodes for stimulation and recording and developed software for the analysis of the recordings. The system uses a stimulator connected to an electrode array for the generation of evoked potentials, an electrode array connected to the amplifier, A/D converter and computer for the recording of evoked potentials, and a dedicated software application. The method has been tested for the assessment of the H-reflex on the triceps surae muscle in six healthy humans. The electrode array with 16 pads was positioned over the posterior aspect of the thigh, while the recording electrode array with 16 pads was positioned over the triceps surae muscle. The stimulator activated all the pads of the stimulation electrode array asynchronously, while the signals were recorded continuously at all the recording sites. The results are topography maps (spatial distribution of evoked potentials) and matrices (spatial visualization of nerve excitability). The software allows the automatic selection of the lowest stimulation intensity to achieve maximal H-reflex amplitude and selection of the recording/stimulation pads according to predefined criteria. The analysis of results shows that the method provides rich information compared with the conventional recording of the H-reflex with regard the spatial distribution.

Expression analysis of genes involved in epigenetic regulation and apoptosis in human malignant haematopoietic cell lines treated with 5-azacytidine.

PURPOSE: The aim of this study was to investigate the modulation of the expression status of 10 different genes involved in epigenetic regulation and apoptosis by the DNA methyltransferase (DNMT) inhibitor 5-azacytidine (5-Aza), as markers of response to treatment, in two different human malignant haematopoietic cell lines. METHODS: In our analysis we used the SybrGreen technology and gene-specific primers for the qRT-PCR analysis of 10 genes, in cDNA of PC-MDS and K562 cell lines, treated by 1 micromole of 5-Aza for 24h. RESULTS: DNMT1 and DNMT3A showed statistically significant decrease of expression in 5-Aza-treated PC-MDS cells, whereas DNMT3B showed significantly decreased expression in 5-Aza-treated K562 cells. The members of the Bcl- 2 family of apoptosis-regulating genes Bcl-2 and Bax showed statistically significant differences in expression, in comparison with non-treated PC-MDS cells. Our most interesting result was the significant upregulation (re-expression) of p15, in 5-Aza-treated PC-MDS cells. CONCLUSION: The re-expression of p15 in PC-MDS cell line evaluated by qRT-PCR makes this novel cell line a suitable model for the studies of pharmacologic demethylation as a plausible mechanism resulting in hematologic response in myelodysplastic syndrome (MDS).

Synthesis and antiproliferative activity of new carboplatin analogues.

PURPOSE: The aim of this study was to present the synthesis and characterization of two carboplatin analogues and to investigate their antiproliferative activity against human tumor cell lines. MATERIALS AND METHODS: The carboplatin analogues cis-1,2-propylendiammine (cyclobutane-1,1-dicarboxylato) platinum (II) (MD2), and cis-izobutylendiammine (cyclobutane-1,1-dicarboxylato)platinum (II) (MD3) were characterized by elemental analysis and (1)H-NMR-measurements. The compounds were tested for antiproliferative activity against the following human tumor cell lines: myelogenous leukemia K562, colon adenocarcinoma HT- 29, breast adenocarcinoma MCF-7, and human lung fetal fibroplast cell line MRC-5. The active substance of carboplatin (MD1) was used as reference compound. Cells were exposed to complexes for 24 h at concentrations ranging from 10(-3) to 10(-8)M. Growth inhibition was evaluated by the colorimetric SRB assay. The IC(50) value of each carboplatin compound was determined by median effects analysis. RESULTS: Both carboplatin analogues induced dose-dependent growth inhibition of human tumor cell lines after 24 h of treatment. The MD3 analogue was 60-fold and the MD2 was 2-foild more active against K562 cell line compared to the referent compound. The activity of both analogues was comparable to the refernt compound against MCF-7 cell line. Colon adenocarcinoma cell line HT-29 was found to be 4-fold less sensitive to MD2 but equally sensitive to MD3 with respect to carboplatin referent compound. Both carboplatin and its analogues induced moderate cytotoxicity on MRC-5 cell line ranging from 25% (10(-7)M) to 46%(10(-3)M). CONCLUSION: This study showed that the two novel carboplatin analogues inhibited human cell lines in a different manner depending on cell line. Carboplatin analogues were more active against human tumor cell lines than against human lung fibroplast cell line MRC-5.