Experimental bases of endoscopic correction of the secretory function of the stomach

The article gives experimental data proving the usage of the method of bloodless reduction of gastric secretion through endoscope in case of peptic ulcer. Pricking around the secretory zones of the stomach with hypertonic glucose solution conducted on 35 mongrel dogs led to a stable reduction of acid producing function of the stomach. Morphological changes of the stomach mucous membrane were mainly expressed in the atrophy of glands. The analysis of the test results gives opportunity to recommend the clinical introduction of the method in complex treatment of peptic ulcer.     

Multiple drug resistance of tumor cells: manifestations, genetic basis, clinical aspects

Data are reviewed concerning the results of study of multidrug-resistant (MDR) tumor cells. MDR often develops in the course of chemotherapy or in vitro selection of tumor cells by vincristine, adriamycin, actinomycin D, colchicine, etc. MDR cells are resistant to all these drugs though their targets and mechanisms of toxic action are quite different. Resistance is due to the decreased accumulation by MDR cells of these compounds. The genetic basis for MDR is amplification of a large genomic region that contains a number of genes coding for products and functions that are under extensive study. Specific karyotype and amplified DNA alterations occur during the development of MDR imitating the processes of appearance and variability of multigene families. The obtained data demonstrate the ways of overcoming of tumor multidrug resistance in clinic.     

Pattern of evolution of amplicons during the development of multiple drug resistance in Djungarian hamster cells

Six cloned DNA fragments representing different portions of the genomic region amplified in multidrug resistant Djungarian hamster cells were used to study amplicon variations in a large number of the resistant cell lines. Expressed correlation exists between the degree of 3 cloned sequences amplification and the level of multidrug resistance. Three other cloned regions amplify coordinately with the latter ones at the initial steps of selection. Later their amplification halts and they mao even eliminate from amplicons of highly resistant cells. The rates and order of elimination of these sequences vary among different independently derived series of multidrug resistant cell lines.     

Species loss of stoneflies (Plecoptera) in the Czech Republic during the 20th century

1. Rapid expansion and intensification of anthropogenic activities in the 20th century has caused profound changes in freshwater assemblages. Unfortunately, knowledge of the extent and causes of species loss (SL) is limited due to the lack of reliable historical data. An unusual data set allows us to compare changes in the most sensitive of aquatic insect orders, the Plecoptera, at some 170 locations in the Czech Republic between two time periods, 1955–1960 and 2006–2010. Historical data (1890–1911) on assemblages of six lowland rivers allow us to infer even earlier changes. 2. Regional stonefly diversity decreased in the first half of the 20th century. Streams at lower altitudes lost a substantial number of species, which were never recovered. In the second half of the century, large‐scale anthropogenic pressure caused SL in all habitats, leading to a dissimilarity of contemporary and previous assemblages. The greatest changes were found at sites affected by organic pollution and a mixture of organic pollution and channelisation or impoundment. Colonisation of new habitats was observed in only three of the 80 species evaluated. 3. Species of moderate habitat specialisation and tolerance to organic pollution were most likely to be lost. Those with narrow specialisations in protected habitats were present in both historical and contemporary collections. 4. Contemporary assemblages are the consequence of more than a 100 years of anthropogenic impacts. In particular, streams at lower altitude and draining intensively exploited landscapes host a mere fragment of the original species complement. Most stonefly species are less frequently present than before, although their assemblages remain almost intact in near‐natural mountain streams. Our analyses demonstrate dramatic restriction of species ranges and, in some cases, apparent changes in altitudinal preference throughout the area.     

Prolongation of oxidative stress by long-lived reactive protein species induced by X-ray radiation and their genotoxic action

Abstract The formation of long-lived reactive protein species of bovine serum albumin (BSA), ovalbumin, casein and casein hydrolyzate with a half-life of 3-5 hours was shown using chemiluminescence induced by X-ray radiation. It was found that long-lived reactive protein species are capable of generating reactive oxygen species (ROS) (H(2)O(2), OH(?), HO(2)(?, 1)O(2)) in the aquatic environment over a long period of time in vitro. The interaction of X-ray-irradiated BSA with DNA in vitro led to the formation of 8-oxoguanine (8-oxo-7,8-dihydroguanine), a biomarker of oxidative damage to DNA. Some natural antioxidants are effective scavengers of ROS (inosine, tryptophan, methionine and ascorbate). They protect DNA from the action of long-lived reactive protein species leading to ROS generation and the formation of 8-oxoguanine. The intravenous injection of X-ray radiation-induced, long-lived reactive protein species to rats, as well as the peroral and intraperitoneal administration of these products to mice, gave rise to cytogenetic injuries in the cells of their red bone marrow through the formation of micronuclei in polychromatophilic erythrocytes. The administration of the same natural antioxidants used for in vitro experiments soon after irradiation made it possible to effectively eliminate the genotoxic action of oxidative stress caused by radiation-induced, long-lived reactive protein species. Our data represent clear evidence that the oxidative damage to proteins induced by X-rays is directly involved in the induction of a response to DNA damage in rodents.     

Heat-induced activation of reducing properties of of sea water

It was shown using the Ellman's reagent that chloride and bicarbonate anions are the heat-induced reducing agents of sea-water, and their combined action is more than additive. Sulfate anions do not exhibit these properties. The influence of sea-water anions on the heat-induced production of hydrogen peroxide was studied by enhanced chemiluminescence in a peroxidase-luminol-p-iodophenol system. In NaCl and NaHCO3 solutions, at concentration and pH values equal to those of sea-water, the production of H2O2 upon heating increased, as compared with water, whereas sulfate anions depressed its formation. By using coumarin-3-carboxylic acid as a fluorescent detector of OH radicals, a substantial increase in the production of radicals in the presence of chloride and bicarbonate anions upon heating was shown. The effect is due to the electron donor properties of these anions, which lead to the decomposition of H2O2 with the formation of OH radicals. The results obtained were considered from the viewpoint of the equivalence of heat and electromagnetic radiation of an absolutely black body. It is supposed that the high-energy quanta of its spectrum lead to the dissociation of anions with the formation of a hydrated electron and radicals. Then a recombination of radicals with the formation of various molecular products takes place.     

Mutational analysis of the functional role of the loop region in the elongation factor G fourth domain in the ribosomal translocation

Seven variants of Thermus thermophilus elongation factor G (EF-G) with mutations in loops of domain IV were constructed by PCR. Point mutations Arg504-->Thr, Pro554-->Thr, or Ile534-->Asp did not affect the GTPase and translocational activities of EF-G. Similar results were obtained for mutants with tetra- or hexapeptide inserts in two loops located at the tip and two loops at the base of domain IV. Insertion of tetrapeptide Gly-Ser-Gly-Thr into loop 501--504 at the tip of domain IV dramatically reduced the activity of EF-G in poly(U)-directed polyphenylalanine synthesis on ribosomes, and halved its translocational activity. The intact conformation of loop Thr501-Gly-Gly-Arg504 was assumed to be essential for sterically perfect, efficient interaction of EF-G with the ribosome. The structural and biochemical data on the 30S subunit and EF-G were analyzed to specify the position of EF-G relative to the 30S and 50S ribosomal subunits.     

90Sr and 137Cs in higher aquatic plants of the Chernobyl nuclear plant exlusion zone]

The content of radionuclides 90Sr and 137Cs in higher aquatic plants of water objects within Chernobyl NPP exclusion zone has been analysed. Biodiversity of phytocenose was studied and species-indicators of radioactive contamination were revealed. The seasonal dynamics of radionuclide content in macrophytes was studied and the role of main aquatic plant clumps in processes of 137Cs and 90Sr distribution in abiotic component of biohydrocenose was demonstrated.