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Biomedical subjects

K Isaković

Publications and source records attributed to K Isaković.

At least 19 recordsLinked to original sources
PubMed1993

Thymus changes in experimentally induced myasthenia gravis.

Experimental myasthenia gravis (EMG) was elicited in female AO rats, 8-12 weeks of age, by injection of 100 micrograms/rat Torpedo marmorata acetylcholine receptor (AChR)-protein incorporated in CFA. Bordetella pertussis, 24 x 10(9) microorganisms, rat, was injected simultaneously as additional adjuvant. Rats were sacrificed on the day of appearance of the clinical signs of EMG, and thymuses were used for histological analysis using stereologic method, and thymocyte subsets were estimated by flow cytometry. Two and three colour fluorescence was applied to determine DN (CD4-CD8-), DP (CD4+CD8+), SP-CD4+ (CD4+CD8-) and SP-CD8+ (CD4-CD8+) subsets, as well as thymocytes expressing TCR alpha/beta. Rats immunized with BSA and rats injected with saline were used as controls. From 56 rats immunized with AChR-protein, 44 rats developed the disease, between day 7 and 11 after immunization. Severity of disease varied from + to + + +. Stereologic analysis of tissue sections revealed a highly significant reduction of thymic cortex and hypertrophy of medulla in EMG thymuses. Similar, but very slight changes were observed in thymuses of rats immunized with BSA. Percentages of DN, SP-CD4+, and SP-CD8+ subpopulations were significantly increased, while the percentage of DP population showed a marked decrease. These preliminary data suggest an alteration of thymocyte maturational events. Whether these changes could be responsible for the initiation of autoimmunity, or are occurring as a secondary phenomenon, after EMG was already established following the injection of cross reactive antigen, is a matter for discussion.

Animals↗
PubMed1992

Parasympathetic innervation of the rat thymus during first life period: histochemical and biochemical study.

In the present study we analyzed development of the rat thymus parasympathetic innervation using histochemical determination of distribution and density of acetylcholinesterase (AChE) positive nerve profiles, as well as biochemical measuring of the activity of this enzyme. Rat thymuses from late embryonal to adult periods of life were analyzed. The AChE-positive nerve profiles were found, for the first time, on day 18 of fetal life in capsule and interlobulary septae, but also in the subcapsulary and cortico-medullary areas. The density of these profiles increased during the thymic development. The AChE positive nerve profiles in subcapsulary region were observed mainly in close proximity to the thymic epithelial cells, while in the cortico-medullary region they were found in apposition to the thymocytes. The biochemical analysis showed that the specific AChE activity in rat thymus was high on day 19 of gestation. A significant increase in the activity of this enzyme was measured by the third day of postnatal development, and its activity remained approximately at the same level up to the day 90. The present results suggest that thymus receives parasympathetic innervation relatively early in ontogeny; in addition, these nerve fibers could be involved in the regulation of the organ activity, at least, through action upon the thymocytes and/or by modulation of the thymic epithelial cell activity.

Acetylcholinesterase↗
PubMed1992

Components of sympathetic innervation of the rat thymus during late fetal and postnatal development: histofluorescence and biochemical study. Sympathetic innervation of the rat thymus.

This study was performed in order to investigate development of sympathetic innervation in the rat thymus. To achieve this aim histofluorescence and biochemical methods were used. The histofluorescence method revealed the presence of sympathetic nervous profiles in this organ for the first time on day 18 of gestation. The density of these profiles and intensity of their fluorescence increased progressively during late embryonal and postnatal development of the organ. In the outer cortex of adult thymus the sympathetic nervous profiles were found mainly in apposition to thymocytes, while in deeper cortex and medulla they were revealed adjacent to thymic epithelial cells. These nervous profiles were also found in close association with thymic autofluorescent cells, which density increased during the thymic postnatal development. Using the fluorometric method the concentrations of neither noradrenaline (NA) and dopamine (DA) nor serotonin (5-HT) were measurable until day 19 of embryogenesis. Their content increased during the postnatal development. The patterns of NA and DA increase during the postnatal development were almost identical, while the pattern of 5-HT increase was quite different. The present results indicate that DA might also be one of the transmitters of the thymic sympathetic nerve supply, as well as that the transmitters of that system can be involved in the regulation of activity of thymic epithelial and autofluorescent cells, but also in the modulation of T cell maturation.

Adrenergic Fibers↗
PubMed1989

Thymic microenvironment in myasthenia gravis.

This study was undertaken to investigate the role of thymic epithelial (TE) cells in the immunopathology of myasthenia gravis (MG). Seventeen thymuses from patients with MG and six normal thymuses were investigated by light and electron microscopy, using a stereologic method. In the myasthenic thymuses the cortex was markedly reduced, while the medulla was hypertrophied and had numerous germinal centers. A subpopulation of cortical TE cells showed a large fibrillar nucleolus and a decreased number of cytoplasmic dense bodies and cysts, indicating decreased function. Medullary TE cells, on the other hand, showed evidence of increased activity with an enlarged euchromatic nucleus and an increased number of cytoplasmic dense bodies. There was a statistically significant negative correlation between the decrease in size of the thymic cortex and the appearance of medullary germinal centers. A significant correlation was also demonstrated between atrophy of cortical TE cells and depletion of cortical thymocytes. Our study shows that both cortical and medullary TE cells are involved in the pathogenesis of MG but have different roles.

Adult↗
PubMed1987

Effects of neonatal gonadectomy on the differentiation of prolactin and growth hormone cells in the chicken adenohypophysis: a quantitative electron microscopic study.

The ultrastructural stereological analysis of prolactin, growth hormone, and gonadotroph cells in the hypophysis of neonatally gonadectomized, 3-month-old male and female chickens was performed. The observed ultrastructural changes (especially of granular endoplasmic reticulum and content of secretory granules) demonstrated reduced biosynthetic activity of prolactin cells in neonatally ovariectomized females and increased activity of prolactin cells in neonatally orchidectomized male chickens.

Animals↗
PubMed1987

Reactivity of B leukemic lymphocytes of patients with chronic lymphocytic leukemia to PWM and PHA.

The ability of leukemic B lymphocytes to proliferate after in vitro stimulation with PWM and PHA was studied in 15 patients with chronic lymphocytic leukemia. Peripheral blood lymphocytes of five healthy subjects as well as purified normal B lymphocytes were used as controls. Leukemic lymphocytes of all donors expressed the same membrane phenotype, M receptor, and B7 and Ia antigens. The lymphocyte populations investigated were not completely free from myelomonocytic cells and contained small numbers of T lymphocytes. DNA synthesis was determined on days 3, 5, and 7 of culture by measuring the incorporation of tritiated thymidine. PWM-induced proliferation of leukemic B lymphocytes of nine patients was within normal limits, while the response of leukemic cells of six patients was very low. On the other hand, all CLL donors responded very well to PHA. Moreover, the response of leukemic B lymphocytes was significantly higher than the response of normal B cells. It was concluded that leukemic B lymphocytes of CLL patients are capable of proliferation after stimulation with PWM and PHA. The mechanisms underlying these responses to PWM and PHA are likely to be different.

B-Lymphocytes↗
PubMed1986

Involution of bursa of fabricius in male and female chickens: a light microscopic histoquantitative study.

A histoquantitative study of the bursa of Fabricius in 3- and 6-month-old male Prelux Bro chickens (domestic selection) was made. All compartments of normal bursal tissue were examined. At 3 months of age, there were no significant differences in bursal weight and structure between males and females. The only difference observed was the higher volume density of follicular cortex and the lower proportion of follicular medulla in males compared to females. In 6-month-old male and female chickens, a different degree of bursal involution was observed. In the bursa of males, an advanced stage of involution was observed, whereas only the initial signs of bursal involution were found in females.

Animals↗
PubMed1985

Ia+T10+ blast cells in acute lymphoblastic leukaemia are precursors of T+ and B+ cells.

Leukaemic blasts isolated from peripheral blood of two patients with non-T, non-B ALL were cultivated for 10-13 days and cell markers were assayed on day 0 and during culture period. Using a panel of cell markers it was demonstrated that the populations of ALL blasts of both patients were composed of T10+Ia+ and "null" blasts. These blasts in the culture differentiated into three cell lines: T and B lymphocytes and myelomonocytic cells. The results thus obtained suggested that within the population of ALL blasts of these two patients there are progenitors of lymphoid and myelomonocytic cells ("null" blasts) and common precursors of T and B lymphocytes (T10+Ia+ blasts). In vitro differentiation of ALL blasts was not affected by LPS and CTPE.

Antigens, Differentiation, T-Lymphocyte↗