Attomole-per Cell Atomic Mass Spectrometry Measurement of Platinum and Gold Drugs in Cultured Lung Cancer Cells

In this study, we developed a strategy to determine atto- and femtomolar amounts of metal ions in lysates and mineralizates of cells (human non-small-cell lung carcinoma (NSCLC, A549) and normal lung (MRC-5)) exposed to cytotoxic metallo-drugs: cisplatin and auranofin at concentrations close to the half-maximal inhibitory drug concentrations (IC₅₀). The developed strategy combines data obtained using biological and chemical approaches. Cell density was determined using two independent cell staining assays using trypan blue, calcein AM/propidium iodide. Metal concentrations in lysed and mineralized cells were established employing a mass spectrometer with inductively coupled plasma (ICP-MS) and equipped with a cross-flow nebulizer working in aspiration mode. It allowed for detecting of less than 1 fg of metal per cell. To decrease the required amount of sample material (from 1.5 mL to ~100 µL) without loss of sensitivity, the sample was introduced as a narrow band into a constant stream of liquid (flow-injection analysis). It was noticed that the selectivity of cisplatin accumulation by cells depends on the incubation time. This complex is accumulated by cells at a lower efficiency than auranofin and is found primarily in the lysate representing the cytosol. In contrast, auranofin interacts with water-insoluble compounds. Despite their different mechanism of action, both metallo-drugs increased the accumulation of transition metal ions responsible for oxidative stress.     

Oriented immobilization of chymotrypsin by use of suitable antibodies coupled to a nonporous solid support.

In order to eliminate the kinetic limitation of chymotryptic hydrolysis of proteins due to diffusion, nonporous hydroxyalkyl methacrylate solid support was developed and used for oriented immobilization of chymotrypsin by means of suitable polyclonal antibodies. Nonporous microspheres were prepared by dispersion copolymerization of 2-hydroxyethyl methacrylate and ethylene dimethacrylate in an alcohol-toluene mixture stabilized with cellulose acetate butyrate. The resulting particles were 1.2 microm in diameter and possessed narrow size distribution. After modification with adipic acid dihydrazide they contained 2 micromol of reactive groups available for coupling of anti-chymotrypsin antibodies. Prepared immunosorbent adsorbed 166.7 microg of chymotrypsin per 1 g of dry carrier. Immobilized chymotrypsin retained practically 100% of its native proteolytic activity. Kinetic parameters of catalysis by chymotrypsin immobilized via this way were improved due to the good steric accessibility of the enzyme active site for high-molecular-mass substrates, when digestion of proteins in batch experiments was used.     

All tilting modules are of finite type

We prove that any infinitely generated tilting module is of finite type, namely that its associated tilting class is the Ext-orthogonal of a set of modules possessing a projective resolution consisting of finitely generated projective modules.

     

The Banach-Zarecki theorem for functions with values in metric spaces

Using an old result of Luzin about his property , we prove a general version of the Banach-Zarecki theorem (on absolute continuity and Luzin's property ).

     

Numerical Solution of the Kiessl Model

The Kiessl model of moisture and heat transfer in generally nonhomogeneous porous materials is analyzed. A weak formulation of the problem of propagation of the state parameters of this model, which are so-called moisture potential and temperature, is derived. An application of the method of discretization in time leads to a system of boundary-value problems for coupled pairs of nonlinear second order ODE's. Some existence and regularity results for these problems are proved and an efficient numerical approach based on a certain special linearization scheme and the Petrov-Galerkin method is suggested.     

Optical pump-terahertz probe spectroscopy of dyes in solutions: probing the dynamics of liquid solvent or solid precipitate?

The optical pump-terahertz probe spectroscopy was used together with ab initio calculations and molecular dynamics simulations to investigate ultrafast dynamics following electronic excitation of Coumarin 153 and TBNC (2,11,20,29-tetra-tert-butyl-2,3-naphtalocyanine) dyes in polar solvents. By scanning the terahertz waveform for different pump-probe delays this experimental technique allows us to obtain two dimensional spectra directly reflecting the temporal response of the system. A distinct signal was obtained for TBNC in chloroform, 2-propanol, and n-butanol, while no signal was recorded for Coumarin 153 in either of these solvents. We explain the nonequilibrium signal detected in TBNC solutions by the presence of a solid, polycrystalline phase of the dye resulting from irradiating the solution by intense optical pulses.     

Effects of interchannel coupling in associative detachment: electron spectra for H+Cl- and H+Br- collisions

We present experimental and theoretical energy spectra of the electrons detached in collisions of slow Cl- and Br- ions with atomic hydrogen. Nonlocal resonance theory predicts two kinds of features in the spectra: steplike structures associated with rovibrational onsets and steep rises associated with interchannel coupling, the latter being absent in a calculation using the simpler local-complex potential theory. Our experimental spectra confirm the presence of both types of structures and thus the necessity of including interchannel coupling to properly describe the product-state distribution.