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Biomedical subjects

N M Ovcinnikov

Publications and source records attributed to N M Ovcinnikov.

17 recordsLinked to original sources
PubMed1976

Ultrastructure of gonococci in acute, chronic, and asymptomatic gonorrhoea.

The authors have made an electron microscope study of material from patients with acute, chronic, and asymptomatic gonorrhoea both before and during treatment with penicillin and kanamycin. Some features of the structure of the gonococcus, e.g. the six-layered cell wall, and of the reactions of the organism in different forms of gonorrhoeae before and during treatment with antibiotics were demonstrated using Ruthenium red staining. Thus, in chronic gonorrhoea, the presence of structures similar to gonococcal L-forms was found to be characteristic, while in asymptomatic gonorrhoea the formation was observed of multimembrane phagosomes hampering the penetration of drugs and antibodies. The positioning of gonococci round epithelial cells was noted (cellular energy). The possibility of changing treatment procedures is examined in the light of these observations.

Acute Disease↗
PubMed1975

Treponema pallidum in nerve fibres.

Ultrathin sections of a rabbit scrotal syphiloma were examined by electron microscopy. Treponemes were observed in the endo-, peri-, and epineurium of the nerve fibre. The significance of these findings, in that infection may be transmitted via the nerve fibres and pain reduced by damage to the afferent fibres, are discussed.

Animals↗
PubMed1975

Further studies of Trichomonas Vaginalis with transmission and scanning electron microscopy.

Under the scanning electron microscope, the body surface of trichomonads appears ruffled and creased, with numerous crater-like depressions, which should probably be interpreted as the initial stage in the formation of digestive vacuoles or pinocytotic vesicles. Having contacted epithelial cells, trichomonads engulf them totally or partially. Various micro-organisms also become a prey of the protozoon. The different stages of phagocytosis are illustrated in electron micrographs. Gonococci have been discovered in phagosomes of T. vaginalis. Usually their phagocytosis is not brought to completion and they survive within the trichomonads (endocytobiosis). This suggests that the agent of gonorrhoea may be maintained within trichomonads in cases of mixed infection. In addition to morphological details described earlier, T. vaginalis has lattice-like and lamellar structures of uncertain function. Spherical forms are found usually in an unfavourable environment or as a result of budding.

Cell Nucleus↗
PubMed1970

Ultrafine structure of te cell elements in hard chancres of the rabbit and their interrelationship with Treponema pallidum.

Investigating the interrelationship between Treponema pallidum and the host cells, the authors have studied under the electron microscope ultrathin sections of cellular elements of rabbit chancres and the condition of the treponemes. A description is given of the structure of the basic cellular elements found in the chancres, particularly the plasma cells since it is in them that the main immunological processes take place.The morphology of the treponemes varies in the course of the pathological process as well as with the type of cell harbouring them. Enveloped in multi-layered membranes, the treponemes may lie within plasma cells and may retain all their characteristic features, indicating that they remain viable and that their envelopes can protect them from the action of antibodies and drugs. In long-standing chancres cyst-like formations with multi-layered membranes have been found.

Animals↗
PubMed1966

Morphology of Treponema pallidum.

In recent years many investigations have been carried out on the morphology of Treponema pallidum by means of the electron microscope, and the use of ultra-thin sections has shown up a number of structural details. However, there is still need for much more evidence before the internal structure of treponemes can be elucidated fully and the functions of the structures interpreted. To provide such evidence, the authors have examined under the electron microscope negative-stained treponemes and ultra-thin sections, using both cultivated strains and treponemes obtained direct from syphilids in people suffering from fresh secondary syphilis. It has been shown that treponemes have a complex structure. T. pallidum has a two-layered outer wall, a cytoplasmic membrane proper, cytoplasm and a bunch of fibrils following a different path in different places on the treponeme. The sites of insertion of the fibrils (the basal granules) were investigated; structures similar to mesosomes and nucleoids were found. Cysts and granular forms are described.

History of Medicine↗
PubMed1965

Long-acting and therapeutic properties of some Soviet and other penicillin preparations in experimental conditions.

The authors describe the results of studies carried out in rabbits infected with syphilis on the therapeutic properties and duration of penicillinaemia of a number of penicillin preparations manufactured in the USSR and of certain others from Czechoslovakia and the USA. These products were studied after intramuscular administration, mainly in doses of 42 000, 84 000 or 168 000 units per kg of body-weight.With all the preparations tested, the first of these doses proved inadequate. Almost, all however, gave satisfactory short-term and long-term results at 84 000 or 168 000 units, but the optimum manner of administration (number of injections and interval between injections) varied according to the preparation. One Soviet and one American preparation showed a considerably lower degree of long-term therapeutic activity and penicillinaemia, although providing a satisfactorily high level of penicillin in the blood for the first few hours after administration.The authors also discuss the reasons for the painfulness of injections of long-acting penicillin and the causes of complications such as embolism following administration.

Animals↗
PubMed1965

A simplified method of performing the Treponema pallidum immobilization test.

The standard TPI test is a complicated technique that can be performed only by highly qualified staff in well-equipped laboratories. This has greatly restricted its application. The author describes a simplified method that does not require complicated apparatus or the use of a gas mixture. The test is performed in diluting pipettes of the type used in making white blood cell counts. The serum to be tested and treponemal suspension containing active complement are taken up successively into the pipette, which is then closed with a rubber ring, shaken and placed in the incubator. A parallel series of control pipettes with inactivated complement is also set up. After incubation, counts of motile and non-motile treponemes are made in the usual way. Comparative studies have shown that the results obtained with this simplified test are comparable in accuracy to those of the standard method. The medium used by the author for preparing the treponemal suspension is also very simple in composition. The technique can therefore be performed in any laboratory that has qualified staff and facilities for keeping rabbits.

Humans↗