An adsorptive transfer technique coupled with brdicka reaction to reveal the importance of metallothionein in chemotherapy with platinum based cytostatics

The drugs based on platinum metals represent one of the oldest, but also one of the most effective groups of chemotherapeutic agents. Thanks to many clinical studies it is known that resistance of tumor cells to drugs is a frequent cause of chemotherapy failure. With regard to platinum based drugs, multidrug resistance can also be connected with increased expression of low-molecular weight protein metallothionein (MT). This study aimed at investigating the interactions of MT with cisplatin or carboplatin, using the adsorptive transfer technique coupled with differential pulse voltammetry Brdicka reaction (AdTS DPV Brdicka reaction), and a comparison of in vitro results with results obtained in vivo. The results obtained from the in vitro study show a strong affinity between platinum based drugs and MT. Further, we analyzed extracts of neuroblastoma cell lines treated with cisplatin or carboplatin. It is clear that neuroblastoma UKF-NB-4 cisplatin-resistant and cisplatin-sensitive cell lines unlikely respond to the presence of the platinum-based cytostatics cisplatin and carboplatin. Finally, we determined the level of MT in samples from rabbits treated with carboplatin and patients with retinoblastoma treated with the same drug.     

An ultra-low energy (30-200 eV) ion-atomic beam source for ion-beam-assisted deposition in ultrahigh vacuum

The paper describes the design and construction of an ion-atomic beam source with an optimized generation of ions for ion-beam-assisted deposition under ultrahigh vacuum (UHV) conditions. The source combines an effusion cell and an electron impact ion source and produces ion beams with ultra-low energies in the range from 30 eV to 200 eV. Decreasing ion beam energy to hyperthermal values (≈10(1) eV) without loosing optimum ionization conditions has been mainly achieved by the incorporation of an ionization chamber with a grid transparent enough for electron and ion beams. In this way the energy and current density of nitrogen ion beams in the order of 10(1) eV and 10(1) nA/cm(2), respectively, have been achieved. The source is capable of growing ultrathin layers or nanostructures at ultra-low energies with a growth rate of several MLs/h. The ion-atomic beam source will be preferentially applied for the synthesis of GaN under UHV conditions.     

Cisplatin electrochemical biosensor

Platinum complexes play an important role in the chemotherapy of various tumour diseases. The aim of this paper was to investigate if a metallothionein (MT) modified hanging mercury drop electrode can be applied as a cisplatin electrochemical biosensor. The modification of the mercury electrode surface by MT and the determination of cisplatin were performed by adsorptive transfer stripping technique and differential pulse voltammetry. The detection limit (3 S/N) of cisplatin ([Pt^II(NH₃)₂Cl₂]⁰) calculated from the decrease of CdT peak was about 2.5 pmol in 5 μl (0.5 μM) at the interaction time of 400 s. Moreover, we tested the influence of human blood serum as a complex biological matrix on the way of determination of cisplatin. On the basis of the obtained results we estimated that we are able to determine tens of picomoles of cisplatin (5 μl drop) in the presence of human blood serum.     

Carbon composite micro- and nano-tubes-based electrodes for detection of nucleic acids

The first aim of this study was to fabricate vertically aligned multiwalled carbon nanotubes (MWCNTs). MWCNTs were successfully prepared by using plasma enhanced chemical vapour deposition. Further, three carbon composite electrodes with different content of carbon particles with various shapes and sizes were prepared and tested on measuring of nucleic acids. The dependences of adenine peak height on the concentration of nucleic acid sample were measured. Carbon composite electrode prepared from a mixture of glassy and spherical carbon powder and MWCNTs had the highest sensitivity to nucleic acids. Other interesting result is the fact that we were able to distinguish signals for all bases using this electrode.     

Electrochemical study of S-nitrosoglutathione and nitric oxide by carbon fibre NO sensor and cyclic voltammetry - possible way of monitoring of nitric oxide

Nitrosation of sulfhydryl group of glutathione, which is highly reactive and is often found conjugated to other molecules via its sulfhydryl moiety, is one of many biological effects of the nitric oxide (NO). This process may serve as a signal event and/or as a deposition of NO to S-nitrosoglutathione (GSNO). Moreover, GSNO may release NO under specific conditions. That is why NO, which has a little lifetime itself, could be distribute for longer distances within the organism. Here, we studied and compared the basic electrochemical characteristics of biological active thiol compounds (GSH, oxidized glutathione and GSNO). In addition, observation of the decomposition process of GSNO using different electrochemical techniques followed. Primarily we studied the influence of scan rate and reducing agent (Tris(2-carboxyethyl)phosphine). The CV calibration equations were linear, R.S.D. about 5%. The detection limits of GSH, GSSG and GSNO expressed as 3 S/N were 9 nM, 4 nM and 20 nM, respectively. In addition, the use of NO selective carbon fibre electrode and cyclic voltammetry for the study of GSNO decomposition catalysed by copper(II) and iron(II) followed.     

Attomole voltammetric determination of metallothionein

Number of authors have concerned with electrochemical analysis of metallothionein. Recently new electroanalytical techniques enabling determination of MT at picomole level has been suggested. The aim of the presented work was to show advantages and disadvantages of the different electrochemical procedures, which are commonly used for the detection of MT—(i) cyclic voltammetry, (ii) differential pulse voltammetry, and (iii) Brdicka reaction. Primarily we aimed on improvement of the mentioned techniques. Using of reducing agent (tris(2-carboxyethyl)phosphine) and combination of the mentioned method with adsorptive transfer stripping technique (AdTS) were the main improvements of the voltammetric method. The detection limits of metallothionein measured by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and DPV Brdicka reaction were 0.5 pmol, 4 fmol and 10 amol, respectively. In addition AdTS DPV Brdicka reaction was used for the determination of metallothionein in human blood serum of 11-year-old girl, which were lead poisoned.     

Approximating isosurfaces by guaranteed-quality triangular meshes

We describe a new method for approximating an implicit surface F by a piecewise-flat triangulated surface whose triangles are as close as possible to equilateral. The main advantage is improved mesh quality which is guaranteed for smooth surfaces. The GradNormal algorithm generates a triangular mesh that gives a piecewise-differentiable approximation of F, with angles between 35.2 and 101.5 degrees. As the mesh size approaches 0, the mesh converges to F through surfaces that are isotopic to F.     

DNA Methylation Mediates EMT Gene Expression in Human Pancreatic Ductal Adenocarcinoma Cell Lines

Due to abundant stroma and extracellular matrix, accompanied by lack of vascularization, pancreatic ductal adenocarcinoma (PDAC) is characterized by severe hypoxia. Epigenetic regulation is likely one of the mechanisms driving hypoxia-induced epithelial-to-mesenchymal transition (EMT), responsible for PDAC aggressiveness and dismal prognosis. To verify the role of DNA methylation in this process, we assessed gene expression and DNA methylation changes in four PDAC cell lines. BxPC-3, MIA PaCa-2, PANC-1, and SU.86.86 cells were exposed to conditioned media containing cytokines and inflammatory molecules in normoxic and hypoxic (1% O₂) conditions for 2 and 6 days. Cancer Inflammation and Immunity Crosstalk and Human Epithelial to Mesenchymal Transition RT² Profiler PCR Arrays were used to identify top deregulated inflammatory and EMT-related genes. Their mRNA expression and DNA methylation were quantified by qRT-PCR and pyrosequencing. BxPC-3 and SU.86.86 cell lines were the most sensitive to hypoxia and inflammation. Although the methylation of gene promoters correlated with gene expression negatively, it was not significantly influenced by experimental conditions. However, DNA methyltransferase inhibitor decitabine efficiently decreased DNA methylation up to 53% and reactivated all silenced genes. These results confirm the role of DNA methylation in EMT-related gene regulation and uncover possible new targets involved in PDAC progression.     

Photography in 1848: Five Case Studies from Central Europe

This article examines the role of photography in the Year of Revolution and the place this topic holds in historiography. Unlike many historical disciplines which perceive 1848 as a turning point in the nineteenth century, the history of photography gives the impression that photographic production was not really affected by the upheavals which otherwise had a great impact on the whole of continental Europe. Collections and archives, however, contain large amounts of visual and written material that indicate the very opposite – that the involvement of photography in the events of 1848 was not rare. Using five examples from Central Europe, three portraits and two cityscapes, this article provides an insight into the cultural and historical backgrounds of photographic production in that year. The article demonstrates the ways in which photographs were involved in the social, political, and cultural events of the time, and how they helped shape ideas about them.     

Experimental study of the behaviour of an isothermal continuous stirred tank reactor in the course of an autocatalytic reaction

The dynamic behaviour of an isothermal continuous stirred tank reactor and of a two-element series of continuous stirred tank reactors in the course of an autocatalytic reaction of bistrichlormethyl-trisulphide with aniline, in methanol at 20°C, was studied. It was shown that the regime of the continuous stirred tank reactor and of the series is unstable ia a certain region of the conversion of the initial reaction component (bis-trichlormethyl-trisulphide) and that in a certain interval of the reaction mixture feed rate the reactor can operate at a single value of the feed rate in two (the series in three) stable states. The values of the bis-trichlormethyl-trisulphide conversion in steady states, as well as the dependence of the conversion on the period of stabilization of the reactor regime, determined experimentally in a continuous stirred tank reactor and in the series are in good agreement with the values computed from the kinetic data, determined in a discontinuous stirred tank reactor.