Assessment of oxidative/nitrative modifications of plasma proteins, selected ROTEM parameters and kinetics of fibrinogen polymerization in patients with multiple myeloma at diagnosis.

Patients with multiple myeloma (MM) are at increased risk of thrombosis. Growing evidence indicates that oxidative and nitrative modifications of proteins, including fibrinogen, may lead to changes in hemostasis. The study compares samples from patients with MM at diagnosis and healthy volunteers with regard to the oxidative/nitrative modifications of proteins, ROTEM and thrombin-catalyzed fibrin polymerization. The content of carbonyl groups in plasma proteins of patients with MM was significantly higher than in controls (2.981 vs. 1.807 nmol/mg of protein, p = 0.005), while no differences were seen in the concentrations of nitrated proteins. Maximum clot firmness readings were significantly higher in the samples of patients than in controls according to FIBTEM test (23.5 vs. 15 mm, p = 0.006). The lag time of the fibrin polymerization process and the velocity of clot lysis (V Lys) were found to be significantly higher in the group of MM patients than controls. In contrast, no marked differences were identified between studied groups in reference to maximal velocity of fibrin polymerization process (V max), maximal absorbance (A max) and plasmin amidolytic activity values. In conclusion, our study demonstrates that at the time of diagnosis, patients with MM demonstrated greater oxidative stress than healthy volunteers, which is reflected in a higher amount of carbonylated proteins. Some prothrombotic features found in ROTEM tests in MM patients were not confirmed by turbidimetry.

FI-on line photochemical reaction for direct chemiluminescence determination of photodegradated chloramphenicol.

A new, simple, clean and selective flow injection strategy based on the tandem photochemical reaction-chemiluminescence detection was applied to the determination of chloramphenicol. The determination is based on the on-line photodegradation of the drug in a glycine buffer at pH 8.8 by using a photoreactor consisting of 697 cmx0.5 mm PTFE tubing helically coiled around an 8 W low-pressure mercury lamp. Photodegradated chloramphenicol is detected by direct chemiluminescence of resulting photo-fragments and their subsequent reaction with potassium permanganate in sulfuric acid medium as oxidant. The method allows the chemiluminescence determination of compounds which do not exhibit native chemiluminescence. The calibration graph was linear up to 14 mug ml(-1) chloramphenicol, the limit of detection was 30 ng ml(-1), the relative standard deviation was 2.4% for 7 mug ml(-1) of the drug and the sample throughput was 60 h(-1). Taking into account the importance of the medium of photodegradation on the mechanism of photodegradation a comparative study in terms of selective was performed for different chemical media employed in the procedure of photodegradation. The proposed method was applied to the determination of chloramphenicol in commercially available pharmaceutical formulations.

A cytoplasmic factor involved in the expression of resistance to C8-ATC in Saccharomyces cerevisiae.

A dozen mutants of Saccharomyces cerevisiae, resistant to C8-ATC have been characterized. C8-ATC was previously established as a biologically toxic compound. Frequency of mutants (10(-7)) was typical for spontaneous mutations. One very stable mutant was characterized extensively. The genetical analysis revealed that resistance in this mutant was determined by single-gene mutation. The rho 0 cells, obtained by ethidium bromide (EB) mutagenesis of the resistant strain, were completely devoid of resistance. A large percentage of rho- cells, obtained by a moderate EB treatment of resistant cells were still able to express resistance to C8-ATC. Therefore we hypothesized that, in our particular strain, a cytoplasmic factor is involved in nuclear determination of resistance.

Effects of C8 alkoxymethylene trimethylammonium chloride on Saccharomyces cerevisiae.

The influence of the C8 alkoxymethylene trimethyloammonium chloride on the growth of Saccharomyces cerevisiae and activity of mitochondria was studied. It was shown that the compound at low concentration inhibited growth on glycerol medium, but considerably higher concentration is involved in the inhibition of growth on glucose medium. C8-ATC also exerted another inhibitory effect on genotypically different yeast strains: it appeared that rho- strain is more sensitive than rho+ strain. C8-ATC compound was not capable itself of inducing petite mutations, but is able of retarding the petite inducing activity of the mutagen ethidium bromide. The result pointed out the role of mitochondria in the expression of sensitivity to the investigated compound.

Biological effect of alkoxymethylene trimethylammonium chlorides on yeast Saccharomyces cerevisiae.

Six compounds of the group of quaternary ammonium salts have been tested for their biological activity using yeasts as a biological system. They have an inhibitory effect on respiration, cell growth and amino acid transport. A destroying action on protoplast regeneration and respiration has been also observed. The studied chemicals appear to have very pleiotropic action, focused on a damage of mitochondrial and cell plasma membranes.

The genetic mapping of the OXI3 mitochondrial region.

Sixteen mit- mutations in the OXI3 region which specifies in Saccharomyces cerevisiae the subunit I of cytochrome oxidase, were ordered by means of deletion mapping and recombination frequency procedures. These results allowed to distinguish a group of mutants with large overlapping deletions. In one of the analyzed mutants the whole investigated segments is deleted.