[Correction of Metabolic Processes in Rats during Chronic Endotoxicosis using Isotope (D/H) Exchange Reactions].

The effect of isotope exchange reactions (deuterium/protium, D/H) on morphofunctional indices and the state of the antioxidant blood system in rats was studied under physiological conditions and during experimental chronic endotoxicosis of hepatorenal genesis. It was demonstrated that introduction of water with a decreased content of deuterium in the food rations of rats results in a decrease in its concentration in the blood plasma by 32-36% (to 98-106 ppm) and in lyophilized liver, kidney, and heart tissues by 13-17% (to 123-128 ppm). It was noted that it is accompanied by correction of metabolic processes, an increase in the functional activity of nonspecific protection system, and an increase in the body weight growth by the 42nd day in the group of animals that passed (for 14 days) the stage of preliminary adaptation with a change in the D/H ratio in the organism.

Solitary cancer cells as a possible source of tumour dormancy?

Metastasis can occur many years after primary tumour treatment. However, the status of the tumour during this period of dormancy is poorly understood. As part of our ongoing experimental studies on mechanisms of metastasis, we have discovered that large numbers of disseminated single cells may persist in secondary sites for extended time periods. Identification of these cells was facilitated by in vivo techniques developed to quantify the fate of individual cells during the metastatic process. Here we review these in vivo techniques and findings. We also discuss the potential clinical implications if dormant solitary cells exist in appreciable numbers in cancer patients.

Critical steps in hematogenous metastasis: an overview.

Metastasis is responsible for most cancer deaths. A better understanding of the process provides opportunities to develop new treatments to prevent metastasis. This article summarizes findings from experimental in vivo videomicroscopy and quantitative studies on metastatic inefficiency, which indicate that early steps in hematogenous metastasis may be quite efficient, but that regulation of cancer cell growth in secondary sites determines metastatic outcome. The authors have identified three key stages of this growth regulation: survival of a subset of single cells, proliferation of a subset of these cells to form preangiogenic micrometastases, and persistence of growth of a subset of these to form vascularized metastases. Formation of clinically relevant metastases is determined by the proportion of cells that proceeds successfully through each stage, and surviving single cells and preangiogenic micrometastases both represent possible sources of tumor dormancy.

Molecular biology of breast cancer metastasis. Clinical implications of experimental studies on metastatic inefficiency.

Recent technological advances have led to an increasing ability to detect isolated tumour cells and groups of tumour cells in patients' blood, lymph nodes or bone marrow. However, the clinical significance of these cells is unclear. Should they be considered as evidence of metastasis, necessitating aggressive treatment, or are they in some cases unrelated to clinical outcome? Quantitative experimental studies on the basic biology of metastatic inefficiency are providing clues that may help in understanding the significance of these cells. This understanding will be of use in guiding clinical studies to assess the significance of isolated tumour cells and micrometastases in cancer patients.

Cellular expression of green fluorescent protein, coupled with high-resolution in vivo videomicroscopy, to monitor steps in tumor metastasis.

High resolution intravital videomicroscopy has provided a powerful tool for directly observing steps in the metastatic process, and for clarifying molecular mechanisms of metastasis and modes of action of anti-metastasis therapeutics. Cells previously have been identified in vivo using exogenously added fluorescent labels, limiting observations to a few cell divisions, or by natural markers (e.g. melanin) expressed only by specific cell types. Here we tested the utility of stable green fluorescent protein (GFP)-transfected cells for monitoring and quantifying sequential steps in the metastatic process. Using CHO-K1 cells that stably express GFP, we document the visualization and quantification by intravital videomicroscopy of sequential steps in metastasis within mouse liver, from initial arrest of cells in the microvasculature to the growth and angiogenesis of metastases. Individual, non-dividing cells, as well as micro- and macrometastases could clearly be detected and quantified, as could fine cellular details such as pseudopodial projections, even after extended periods of in vivo growth. We quantified the size distribution of micrometastases and their locations relative to the liver surface using 50 micrometer thick formalin-fixed tissue sections. The data suggest preferential growth and survival of micrometastases near the liver surface. Furthermore, we observed a small population of single cells that persisted over the 11 day observation period, which may represent dormant cells with potential for subsequent proliferation. This study demonstrates the advantages of GFP-expressing cells, coupled with real-time high resolution videomicroscopy, for long-term in vivo studies to visualize and quantify sequential steps of the metastatic process.

[Proteins, associated with 50S-ribosomal subunits of Escherichia coli MRE600]. / Belki, assotsirovannye s 50S-ribosomnymi sub''edinitsami Escherichia coli MRE600.

The proteins associated with the ribosomal subunits having the molecular masses from 158 to 47 kDa were isolated from hyaloplasmic, nucleoid and membrane fractions of Escherichia coli MRE600 cells. The proteins are eliminated from 50S subunits of ribosomes by thrice washing with the 1 M ammonium chloride buffer. 50S subunit proteins were found to be immunologically related to the inner membrane proteins. The native 50S subunits of ribosomes possess the expressed ATP-ase activity, while the washed off subunits lose it completely.

[Transposon-mediated integration of the RP1 plasmid into chromosomes of methylotrophic bacteria]. / Transpozonoposredovannaia integratsiia plazmidy RP1 v khromosomu metilotrofnoi bakterii.

The homology region between the DNA of plasmid RP1ts::Tn601 and chromosome of the thermotolerant methylotrophic bacterium Methylobacterium sp. SKF240 has been constructed by transposon Tn601 translocation into the chromosome. The clones of Methylobacterium sp. SKF240 having integrated the plasmid RP1 into the chromosome have been obtained by conjugation on the basis of above mentioned genetic technique. The integration of plasmid RP1 into the chromosomal DNA of the methylotroph has been confirmed by the genetic and electrophoretic methods. Clones harbouring the integrated plasmid are able to transfer the chromosomal genes for methionine and isoleucine-valine synthesis to the recipient cells of P. aeruginosa PAO ML4262 by conjugation.

[Characteristics of mutagenesis and repair following UV irradiation in the methylotrophic bacterium Pseudomonas methanolica]. / Osobennosti mutageneza i reparatsii posle UF-oblucheniia u metilotrofnoi bakterii Pseudomonas methanolica.

The methylotrophic bacterium Pseudomonas methanolica was shown to be very resistant to the bactericidal and mutagenic action of UV irradiation. The activity of reparation processes after UV irradiation was also detected as well as a weak photoreactivating activity in P. methanolica. The decrease in the survival rate of irradiated cells under the action of caffeine and acriflavine, reparation inhibitors, is indicative of the activity of the excision reparation systems and, possibly, the recombination branch of postreplicative reparation. No activity of the inducible reparation system was found. It has been concluded that the elevated resistance of P. methanolica cells to the bactericidal and mutagenic action of short-wavelength UV irradiation is associated with the activity of the reparation systems.

[Purification of plasmid DNA by chromatographic methods]. / Ochistka plazmidnoi DNK khromatograficheskimi metodami.

Chromatographic methods have been used to purify the DNA of plasmid RP1. DNA was purified in two stages. DNA was precipitated by ethanol and separated from RNA and proteins in Sepharose 4B column after lysis of plasmid containing cells by alkaline solution of sodium dodecylsulphate. Separation of the total DNA preparation and isolation of plasmid DNA was achieved at the second stage by chromatography on the hydroxyapatite column. The resulting purified plasmid DNA was free of RNA, protein and linear fragments of chromosomal DNA. The plasmid DNA kept intact native structure and possessed the transforming activity. The DNA of RP1 yield after purification by the described technique presented 70-80 micrograms per g of wet biomass.

[Transfer of prophage Mu into methylotrophic bacteria in the plasmid RP4]. / Peredacha profaga Mu metilotrofnym bakteriiam v sostave plazmidy RP4.

Bacteriophage Mu genome has been transferred into the cells of Pseudomonas methanolica and Methylobacterium sp. SKF240, that are naturally resistant to the bacteriophage, as a fragment of a hybrid plasmid RP4::Mu cts62. Temperature induction of the bacteriophage results in host cell lysis. Plasmid RP::Mu cis62 is maintained in methylotrophic cells presenting a cointegrative structure. The genetic and electrophoretic, analyses of the DNA isolated from transconjugant cells have confirmed the conclusion. Bacteriophage Mu propagation has been shown to be restricted in methylotrophic cells.

[Carotenoid pigments and the enhanced resistance of Pseudomonas methanolica to the action of ultraviolet radiation]. / Karotinoidnye pigmenty i povyshennaia ustoichivost' Pseudomonas methanolica k deistviiu ul'trafioletovogo izlucheniia.

The correlation was studied between the elevated resistance of Pseudomonas methanolica, a facultative methylotroph, to the bactericidal action of UV (254 nm) and the content of a pink pigment in this organism. Absorption spectra of cell extracts containing the pigment were recorded. The ethanol and acetone extracts had two absorption maxima at 420-430 and 500-510 nm, respectively, which was typical of carotenoids. The culture with the pigment and its variant without the pigment had nearly identical survival rates. Therefore, the elevated resistance of P. methanolica cells seems to stem from the activity of DNA reparation cellular systems rather than from the presence of carotenoid pigments in the cells.