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Biomedical subjects

V Vĕtvicka

Publications and source records attributed to V Vĕtvicka.

At least 37 records · Page 2Linked to original sources
PubMed1990

Omental dendritic cells: Ia expression and relation to macrophages.

Rat omental dendritic cells (ODC) occur in two forms, mainly spindle-shaped, Ia-, on the surface, and stellar, Ia+ within the omentum. Like macrophages, most ODC label with W3/25 mAb and have a demonstrable activity of non-specific esterase, acid phosphatase and ATPase. Up to 30% of ODC are actively phagocytic. The proportion of Ia+ ODC rises 7 days after ip antigenic stimulation and there seems to be a reciprocal development of Ia positivity and phagocytic capacity between ODC and macrophages 3 and 5 days after ip immunization. ODC contribute to the overall fluctuation of Ia expression in the entire omentum after immunization. Ia+ ODC display a linear arrangement along preilymphatic spaces and may be related to the formation of new lymph vessels. They also constitute the stroma of pseudofollicles containing clusters of what are presumably T-helper lymphocytes closely attached to ODC, scattered suppressor T lymphocytes and B cells accumulating in later stages at the immune response.

Acid Phosphatase↗
PubMed1990

Properties of macrophages from high- and low-responder strains of mice. II. The expression of Fc receptors.

Simultaneous expression of Fc receptors was studied on the model of peritoneal macrophages from two inbred strains of mice, A/J and C57BL/10ScSn, so-called high- and low-responders. Sheep red blood cells and/or synthetic polymer microspheres both coated with monoclonal antibodies of different isotypes were used for detection of Fc receptors. It was proved that the majority of macrophages bear more than one type of Fc receptors, moreover, macrophages expressing at least three types of Fc receptors simultaneously were detected. Both mouse strains vary in the presence of different subpopulations of macrophages bearing particular sets of Fc receptors.

Animals↗
PubMed1990

Phagocytosis of synthetic particles in earthworms. Effect of antigenic stimulation and opsonization.

We examined the phagocytic activity of coelomocytes in earthworms Lumbricus terrestris. The synthetic polymeric HEMA particles were used in this study. The phagocytic capacity was increased after the protein administration or preincubation of HEMA particles with coelomic fluid. Furthermore, we isolated and characterized the proteins adsorbed on the surface of the particles which have opsonin-like properties.

Animals↗
PubMed1990

Different colony formation in low- and high-responding strains of mice.

B lymphocytes from the immunized low-responding strain B10 did not form colonies after stimulation with SRBC in semisolid agar cultures, this defect was reparable by simultaneous stimulation with LPS and SRBC. The colony formation of macrophages obtained from control and primarily immunized mice was comparable, but after secondary immunization the B10-derived macrophages formed only 50% of colonies. The formation of haemopoietic CFU-S colonies is in B10 strain significantly suppressed by both primary and secondary immunization.

Animals↗
PubMed1989

The stimulatory effect of bilirubin on phagocytic activity.

The effect of an i.p. application of bilirubin on phagocytic activity and the arrangement of the microtubule system of murine peritoneal macrophages were examined. A significant increase of phagocytic activity was observed 3 h after bilirubin treatment, and normal value were reached after 3 d. The increase of the extent of the microtubule system was comparable with that of enhanced phagocytosis but normal values were observed after 1 d.

Animals↗
PubMed1989

The transmembrane and intracellular transport of drugs: interactions with the cytoskeletal network.

The transport of molecules and/or larger corpuscular material into the cells takes place in plasma membrane and plasma membrane-derived vesicles and vacuoles. Transmembrane and intracellular transport of various materials plays an essential role in the final cellular effects of the drugs. Cytoskeletal network forms a three-dimensional array in the cytoplasm of cells and is closely related to the plasma membrane. Thus, the cytoskeleton significantly affects various processes such as endocytosis, organization and fluidity of the membrane, activity of ion channels, or localization of intracellular organelles. The interactions of the cytoskeletal system with cellular transport of drugs are the scope of this article.

Animals↗
PubMed1989

Different handling of antigen by macrophages of low-responder C57BL/10ScSn strain and high-responder A/J strain of mice. II. Antigen uptake.

The uptake of 51Cr-SRBC and 125I-ARS-BG6 in the liver and spleen of non-immune low IgG responder C57BL/10ScSn mice is higher than in the high-responder A/J strain. After immunization with SRBC, the uptake in the spleen of A/J mice is ten times higher and that in the liver three times higher than in C57BL/10ScSn mice. The higher uptake of the well responding A/J strain, which is antigen specific, is due not only to a higher level of opsonizing antibodies. Endotoxin stimulation, which increases the IgG formation of the low-responding strain, does not increase the uptake in this strain. In the low-responder strain there is a considerable level of free 51Cr in the serum and kidney within 5 min after antigen injection, suggesting a high catabolic rate of the antigen. In contrast, at that time in the A/J strain virtually all of the radioactivity is still bound to the erythrocyte fraction. Ultrastructural observations suggest that in the low-responding strain the antigen residues survived in macrophages for a long period of time. The results provide evidence of differences between the metabolic activity of macrophage populations of both strains which could be related to the low IgG response of the strain C57BL/10ScSn.

Animals↗
PubMed1988

Antibody-directed affinity therapy applied to the immune system: in vivo effectiveness and limited toxicity of daunomycin conjugated to HPMA copolymers and targeting antibody.

The applicability of targeting therapy intervention in lymphatic tissue was studied. The effect was measured as the inhibition of anti-sheep red blood cell antibody response expressed in plaque-forming cells. Daunomycin was used as the effective drug and polyclonal and monoclonal anti-Thy 1.2 or anti-Iak antibody served for targeting. Both components were coupled to a soluble N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer with oligopeptidic side sequences which permitted a controlled release of the drug in the target tissue. HPMA copolymer conjugates with side sequences Gly-Phe-Leu-Gly cleavable by lysosomal enzymes decreased in vivo the antibody reaction by 60-85%. A comparable amount of free targeting antibody was without a significant effect. Injection of targeted daunomycin decreased the toxicity of the drug against hematopoietic precursors in bone marrow colony-forming unit-spleen 80 times compared to the same amount of free drug. The in vivo effectiveness of targeted daunomycin was confirmed morphologically. Application of free daunomycin lead to a significant irritation of Kupffer cells in liver while none of the daunomycin-antibody-copolymer conjugate had such an effect.

Acrylates↗
PubMed1988

Alpha-fetoprotein and phagocytosis in athymic nude mice.

Alpha-fetoprotein (AFP) was found to suppress the phagocytic activity of the blood monocytes and neutrophils in vitro. The amounts of AFP detectable by immunofluorescence in the livers of nu/nu, nu/+ and +/+ mice were quite comparable, and thus could not have been responsible for the alterations in phagocytosis found in leukocytes of athymic nude mice during their ontogenetic development.

Age Factors↗
PubMed1988

Limitations of transmembrane transport in drug delivery.

The plasma membrane of all living cells controls the flow of substances, energy as well as information, between the internal cell order and surrounding cell disorder. There are three general routes along which substances may cross this barrier; free diffusion, passive and active transport, and endocytic processes. The subject of polymer drugs where biologically inert polymers bear therapeutically active low molecular weight drugs and targeting moiety became a popular issue in last decade. This review is devoted to the question of the interaction of drugs with the plasma membrane and their transport across it. As the polymer-drug conjugates are macromolecular substances, the main emphasis is focused on the problems of phagocytosis and pinocytosis.

Biological Transport↗
PubMed1988

Effects of bilirubin on murine peritoneal and spleen cells.

The effect of bilirubin on murine peritoneal and spleen cells was investigated. Bilirubin was found to have a strong and rapid effect on the expression of various kinds of Fc receptors on peritoneal macrophages. Significant changes were observed 30 min after the infection of bilirubin. The return to normal values was not observed earlier than after 24 h. The effect of bilirubin on Fc receptor expression of splenic macrophages was less pronounced. Expression of Ia antigen on macrophages was not influenced by bilirubin. The changes in percentage of sIg+ and Thy 1.2+ lymphocytes reflect a change in the ratio of T to B cells in the peritoneal cavity, as bilirubin caused 40% increase in numbers of B cells and a similar decrease in numbers of T cells. The percentage of splenic B lymphocytes was not influenced by bilirubin injection; but the ratio of T helper to suppressor cells was altered.

Animals↗
PubMed1987

Polymer microbeads in immunology.

Synthetic polymer microbeads have been studied extensively and the required properties, including monodispersity and size range 0.05-10 microns can best be achieved by radiation polymerization based on methacrylate derivatives. Fluorochrome-conjugated beads can be used for cell surface markers and simultaneously to study phagocytosis. The paper reviews some of these applications. Cell separation techniques are also described. Future possibilities for immunological and cell biology studies are discussed.

Animals↗
PubMed1987

Changes in the arrangement of the microtubule system of murine peritoneal cells after an antigenic stimulation.

We determined two characteristic morphological patterns typical for the organization of microtubule systems of murine peritoneal macrophages and lymphocytes. A small number of both cell types formed uropods with an axial bundle of microtubules. This number remains practically unchanged during 48 h of cultivation in non-antigenic environment but grows rapidly in the presence of an antigen.

Animals↗
PubMed1987

Membrane and functional characterization of lymphoid and macrophage populations of Peyer's patches from adult and aged mice.

Properties of macrophages isolated from Peyer's patches were compared with properties of peritoneal macrophages. We found a very low expression of all types of Fc receptors as well as a low expression of Ia antigens on Peyer's patch macrophages. No substantial changes in the levels of FcR and Ia antigen expression were found during the process of ageing. The investigation of phagocytic activity showed the activated state of Peyer's patch macrophages. Comparing the surface markers of lymphocytes obtained from Peyer's patches of mice of different ages, we found no differences in the numbers of sIg+, Thy-+ or L3T4+ lymphocytes. The numbers of FcR+ and Lyt 2.2+ lymphocytes decreased markedly with age.

Aging↗
PubMed1987

Immunologic markers and fine structure of alveolar cells in germfree pigs.

The objective of this study was to evaluate neonatal development of alveolar cells without any antigenic stimulation. The cells obtained by bronchoalveolar lavage from newborn and germfree Minnesota miniature piglets were characterized ultrastructurally and using different markers of pig lymphocytes and macrophages. Alveolar cells from newborn animals did not express any immunologic markers or phagocytic activity. Cells of the pulmonary immune system appeared in the airways at the twelfth hour, phagocytosing macrophages within the first day of postnatal life. Fc receptors were expressed sooner than complement receptors. Almost all lymphocytes were null cells. Macrophages and lymphocytes immigrated into alveolar spaces independently of external antigenic stimuli.

Animals↗
PubMed1986

Separation of human lymphoid cells by affinity chromatography and cell surface labelling by hydroxyethyl methacrylate particles using monoclonal antibodies.

The hydroxyalkyl methacrylate gel Separon, Sepharose 6MB and polystyrene dishes with bound antibodies were used for affinity chromatography of cells isolated from human tonsils and peripheral blood. Enrichment of T cells by filtration through anti-human immunoglobulin Separon or Sepharose 6MB columns was comparable to that achieved by "panning" on dishes or by Nylon wool column fractionation. High enrichment of B cells was obtained when cells pretreated with monoclonal anti-T cell antibodies were fractionated on columns or dishes where anti-mouse antibody was bound. Hydroxyethyl methacrylate copolymer microspheres were conjugated with monoclonal antibodies directed against surface markers of human lymphocytes or with anti-mouse immunoglobulin antibodies and used for surface labelling of cells. The results obtained by immunofluorescence were in good correlation with labelling by hydroxyethyl methacrylate immunobeads.

Animals↗