Biomedical subjects

M Savova

Publications and source records attributed to M Savova.

4 recordsLinked to original sources

PubMed2003

Serotonin 1B knockout mice exhibit a task-dependent selective learning facilitation.

Serotonin 1B knockout (KO) mice exhibit better spatial reference memory performance in the Morris water maze than their wild type (WT) controls. The present study was aimed at dissecting the underlying cognitive bases of this facilitation using a stepwise water maze paradigm. The performance of KO mice did not differ from WT in a single start-goal task, nor when using two opposite starts. However, KO mice exhibited better performance in stages requiring cognitive flexibility or the higher level of spatial navigation planning (standard version). In a short-term memory version of the task, no such genotype effect was observed, confirming our previous findings. These results suggest that the serotonin 1B receptor gene deletion selectively enhances learning performance when the cognitive requirement of the task is elevated.

Animals↗

PubMed1985

[Electron microscopic research on an experimental infection in chicks caused by the infectious bursal virus].

A total of 18 birds at the age of 25 days were infected intraocularly with the pathogenic strain 52/70 of the infectious bursitis virus. The bursa of Fabricius and the thymus were sampled for electron-microscopic investigations. The ultrastructural changes in the infected cells consisted in pycnosis of the lymphocyte and macrophage nuclei, vacuolization of the cytoplasm, and the production of lipid droplets as well as of inclusion bodies of varying density, myelin figures, multivericular bodies, and other irregular structures in the cytoplasm. These changes were slightly visible at the 24th hour, were characteristic at the 48th hour, and were well manifested at the 72nd hour following infection. Beside the degenerative changes in the cytoplasm of the affected cells (mainly lymphocytes) there were at the 24th hour of infection tiny-granular matter of fibre-like structure and particles within it of varying electron density. In the later phases (at the 48 h and the 72nd hour) viral particles that were either free or in the vacuoles were predominantly seen in the cytoplasm of the macrophages, having a dia of 50-60 nm and a hexagonal form, with crystalographic arrangement. It was also demonstrated that the replication of the virus of the infectious bursal infection took place in lymphocytes, and in the later stages of infection--chiefly in macrophages. These were the two main types of cells in which virus replication was seen to take place.

Animals↗

PubMed1984

[Pathomorphological studies of infectious bursitis in chickens with a subclinical infection].

A total of 70 growing birds of three breed, aged 1 to 42 days in which the disease was serologically and morphologically demonstrated were studied. No apparent gross lesions were established with any of the birds. Histologically, there was in the bursa of Fabricius a drop of the lymphocytes within the lymphoreticular system of the follicles. There were in the center of the follicles histiocytes, and epithelial proliferation was seen with single follicles. The cover epithelium of the bursa presented vacuolar degeneration. The white pulp of the spleen was poorer in lymphocytes. There were in the thymus and the cecal tonsils of individual birds pseudoeosinophile leukocytes within the lymphoreticular system as well as lymphomalacia. Serologically, in birds aged 1-2 weeks high titers of antibodies were discovered (1:4 and 1:16), while in those aged 3-6 weeks the antibodies dropped--to 1:3 (with the 3-week-old ones) and to nil (in the 4-, 5-, and 6-week-old ones), which corresponded to the morphologic changes in the investigated organs. It was histologically demonstrated that the virus of infectious bursitis affects the lymphoreticular system of the birds as early as the first 20 days following hatching, which invariably has a bearing on their immune resistance.

Animals↗

PubMed1984

[Asymptomatic course of infectious bursitis in chickens].

Morphologic and serologic studies were carried out with a total of 190 birds of three breeds (Cornish, White Plymouth Rock, and Gillink) aged 1 to 50 days, with which Gumboro disease ran a symptomless course. Gross lesions were established in 3.1 per cent of the birds only. Histopathologically, however, there were changes in the bursa Fabricii (73.6 per cent), the spleen (68.4 per cent), the thymus (10.5 per cent), and the cecal tonsils (5.2 per cent). The microscopic lesions consisted in malacia of the elements of the lympho-reticular system. Serologically, mother precipitating antibodies were found in the first 2-3 weeks following hatching. The postinfection antibodies were shown to be released in the sixth to seventh week of even later. It was demonstrated that the symptomless course of infectious bursitis in birds could be histologically and serologically diagnosed as early as the first week following hatching, whereas the morphologic changes were mostly manifested between the 36th and the 50th day of age.

Animals↗