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Biomedical subjects

V M Semenov

Publications and source records attributed to V M Semenov.

15 recordsLinked to original sources
PubMed1998

[One of the possible ways of propagation of the unicellular parasites Sarcocystis muris in the musculature of the intermediate host].

20 laboratory mice (Mus musculus) were fed each a single dose of 20,000 Sarcocystis muris sporocysts to be then sacrificed 1, 2.5, 4, 6 and 10 months following infection (p.i.). A visual infection of the murine corps demonstrated that the number of sarcocysts per animal increased regularly as the time of infection was progressing, being eventually higher after 6 and 10 months p.i. than within 1-4 months p.i. This phenomenon was poorly understood from the knowledge that the tissue cysts (sarcocysts) are able to increase in size, rather than in number, and that the original number of sarcocysts largely depends on the number of precystic merozoites available. In our experiments, each of 20 mice was fed an equal number of sporocysts, and thus the number of precystic merozoites ought to be expected also more or less equal. EM investigation of murine skeletal muscles 6 and 10 months p.i. revealed, along with numerous normal sarcocysts, the presence of some separate, individual zoites, both within and outside the muscle fibre, in the endomysium. Besides, a colony of zoites, living freely without any visible common wall, was detected within a muscle fibre adjacent to another one, containing a sarcocyst of normal structure. These zoites may have originated from one or more sarcocysts, whose cyst walls were spontaneously broken, time after another, and thus led the cyst cells go out. These discharged zoites could either perish, being enzymatically degraded, or penetrate the neighbouring muscle fibres to proceed their further development. The colony making zoites were confined to two cell types only: the intermediate cells and the merozoites (gamonts). No metrocytes were recognized due, presumably, to inability of these little differentiated cells, devoid of penetrative organelles, to invade the host muscle cell. The colony of zoites turned out to be a developing population of live cells, able to destroy progressively the harbouring muscle fibre, except its basal membrane and sarcolemma. It does not seem unlikely that the outer coverings of the infected cell could be transformed eventually into a cyst wall to make, thus, a new sarcocyst. The above phenomena have never been found in murine muscles earlier than 6 months p.i. Although these facts are few and far between, they may prompt a possible mechanism of sarcocyst increase in number, in the intermediate host with age, even without any additional sporocyst contamination.

Animals↗
PubMed1997

[The localization and functional significance of arylsulfatases in parasitic sarcosporidian protozoa in the tissue-cyst life cycle phase].

The hydrolytic enzymes arylsulphatases (AS) were detected in developing tissue cysts of Sarcocystis ovifelis, using two methods: the Goldfischer lead technique, with two different pH values-5.5 (AS-A) and 4.2 (AS-B), and the Hopsu-Havu barium technique (Gayer, 1974). The enzymatic activity was identified by the presence of an electron dense finely granulated precipitation. In cyst cells, lead sulphate precipitation was spotted only in the inner membrane complex (IC) of the pellicle, whereas barium sulphate marked, in addition, the plasma membrane. Besides, AS activity was detected in the endoplasmic reticulum, Golgi complex, lysosomes and micronemes of cyst cells. Of interest is the finding of AS in the outer membrane of IC and matrix of pellicular evaginations. In the cyst ground substance (CGS) of S. ovifelis AS activity is confined to the membrane and matrix of transport vesicles, originating from cyst cell pellicle evaginations. These cystic vesicles carry enzymes from the places of their synthesis, in the cyst cells, to the tissue cyst periphery near the cyst wall. In the CGS, the obvious precipitations of lead and barium sulphate, respectively, are seen around some cyst cells being in the state of destroying due to natural death, and around so-called apoptotic-like bodies made from the destroyed cells. AS activity is seen both in the cyst wall and in vesicles separating from the wall ("wall vesicles") that find eventually their way in the cytoplasm of infected muscle cells, the granulation being observed around destroyed organelles of such cells. The investigated dynamics of AS movement, by means of the transport cystic and wall vesicles, extends general knowledge of the distant metabolic interaction between cells of the host and the parasite in tissue cysts of Sarcocystis spp.

Animals↗
PubMed1996

[The effect of coccidia of the genus Sarcocystis on the morphofunctional organization of the skeletal musculature in experimentally infected mice. I. The muscle fiber].

At the ultrastructural level, the cellular response of skeletal muscles on developing Sarcocystis muris sarcocysts has been followed in mice at different times after sporocyst feeding, i.e. in 1, 2.5, 6 and 10 months, resp. The developing cyst creates a progressive degeneration of the infected muscle cell that involves organelle disorganization and formation of numerous vacuoles in the cytoplasm as a consequence of cell edema. Products of the host cell degradation, shaped as fibrillar-granular structures, are seen to find their way to the cyst wall outgrowings, where they become denser and on being covered with membranes appear eventually in the sarcocyst ground substance. Later on, the membranes around the granules disappear. In the course of its development, the sarcocyst totally destroys not only the harbouring muscle cell and the nearest connective tissue elements of the endomysium, but also the previously intact neighbouring cells. The involvement of some proteolytic enzymes in this process is suggested.

Animals↗
PubMed1989

[The development and a clinical trial of an erythrocytic diagnostic agent for determining antibodies to the liver-specific lipoprotein].

A simple method for the preparation of purified liver-specific protein has been developed and a sensitive and specific test-system has been created on its basis for the detection of antiLSP. The titres of antiLSP correlate with the activity of the pathological processes in patients with acute and chronic hepatitides. Immunosuppressive therapy results in elimination of antiLSP.

Antibodies↗
PubMed1984

[Ultrastructure of the fibrillar center in oocyte nucleoli at the diplonema stage in the golden hamster].

Topography of the fibrillar centre and other nucleolar components has been studied during the oocyte large growth in golden hamster. The fibrillar centre was found to show a tendency to marginal distribution, which is characteristic of the initial period of large growth and its final stages. Localization of the fibrillar centre correlates with the amount of granular component and the general level of the nucleus transcription activity. A possible role of the marginal localization of the nucleolus fibrillar centre in maturating oocytes is discussed as a distinguishing trait of chromosomes that enter into meiosis.

Animals↗
PubMedDate not supplied

[Seasonal dynamics of atmospheric methane oxidation in gray forest soils].

Seasonal fluctuations in the methane flow in the soil-atmosphere system were determined for gray forest soils of Central Russia. Consumption of atmospheric methane was found to exceed methane emission in gray forest soils under forest and in agrocenosis. The average annual rates of atmospheric methane consumption by the soil under forest and in agrocenosis were 0.026 and 0.008 mg CH4-C/(m2 h), respectively. The annual rate of atmospheric methane oxidation in the gray forest soils of Moscow oblast was estimated to be 0.68 kton. Seasonal fluctuations in the methane oxidation activity were due to changes in the hydrothermal conditions and in the reserves of readily decomposable organic matter and mineral nitrogen, as well as to changes in the activity of methane oxidizers.

Air↗
PubMedDate not supplied

[Physicochemical and biological factors affecting atmospheric methane oxidation in gray forest soils].

The decline of methane oxidizing activities in gray forest soil upon its conversion into arable land was shown to be caused by major changes in biotic and physicochemical properties of soil. Using the method of immune serums, methane-oxidizing bacteria were detected in both forest and agricultural soils, but their populations differed significantly in both abundance and composition. In the forest soil, the number of methanotrophs was an order of magnitude higher than in arable soil, amounting to 3.5 x 10(8) and 0.24 x 10(8) cells/g soil, respectively. All methane-oxidizing bacteria identified in the forest soil belonged to the genus Methylocystis, and 94% of these were represented by a single species, M. parvus. The arable soil was dominated by type I methanotrophs (Methylobacter and Methylomonas, 67.6%), occurring along with bacteria of the genus Methylocystis. In addition, arable soil is characterized by a low content of microbial biomass, lower porosity and water permeability of soil aggregates, and the predominance of nitrogen mineralization processes over those of nitrogen immobilization. These factors can also contribute to lower rates of methane oxidation in arable soil as compared to forest soil.

Agriculture↗
PubMedDate not supplied

[Persistence of viruses in rheumatoid arthritis].

Humoral and cell-mediated immune response to antigens of hepatitis B (HBsAg and HBeAg), delta-virus, rubella, and measles viruses was studied. Detection in a number of patients with rheumatoid arthritis of HBsAg and HBeAg in blood sera permits a conclusion that productive virus infection is formed in such patients. At the same time in patients with rheumatoid arthritis areactivity of immunocytes to HBsAg and HBeAg was found while marked sensitization of lymphocytes to rubella virus antigens was demonstrated. The patients with rheumatoid arthritis, however, do not develop mere long-term carrier state of hepatitis B virus but form primary chronic hepatitis as a consequence of virus infection. This is indicated by an increase in the level of alanine aminotransferase (1.6 +/- 0.8 mmol/l) and detection of antibody to delta-virus in such patients (28.6%).

Antibodies, Viral↗