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Biomedical subjects

A Macela

Publications and source records attributed to A Macela.

At least 37 records · Page 2Linked to original sources
PubMed1997

Early consequences of macrophage-Francisella tularensis interaction under the influence of different genetic background in mice.

The induction, regulation and expression of protective immunity against Francisella tularensis LVS infection is dependent on the results of primary interaction between the cells of host's immunoregulatory system and the microbe. The early events, at least on the side of macrophages, are under the genetic control. To determine the impact of genes that might be involved in the control of resistance to Francisella tularensis LVS infection, we have used three different inbred strains of mice with increasing resistance to this infection in order C3H/HeJ (Lpsd), C3H/HeN (Lpsn"), and C57B1/10N (Lpsn"). The controlled production of IL-10, IFN-gamma, and TNF-alpha coupled with increased production of reactive oxygen metabolites during early phase of infection distinguished less susceptible C3H/HeN mice from their more susceptible cogenic C3H/HeJ counterparts. The enhancement of oxidative metabolism that appeared on day 5 after the infection of both C3H/HeN and C57B1/10N mice closely correlated with increasing resistance of these two strains of mice to Francisella tularensis LVS infection. These mice were also capable to reach the highest level of TNF-alpha on day 5 after the infection. At the same time interval, only C57B1/10N mice produced significantly enhanced level of nitric oxide. Overall, these parameters may suggest their possible biological role in early-phase resistance to Francisella tularensis LVS infection and their subsequent consequences for ultimate control of infection and its clearance.

Animals↗
PubMed1997

Natural resistance to infection with intracellular pathogens: cross-talk between Nramp1 and Lps genes.

This study was designed to analyze the association of Nramp1 and/or Lps genes with differential protein expression in macrophages in order to select candidate proteins that might be related to resistance/susceptibility to various microbial infections under the control of the Nramp1 and/or Lps genes. The macrophage cell lines derived from bone marrow of Nramp1 or Lps congenic mice were utilized and high-resolution two-dimensional electrophoreis (2-DE), separating proteins according to their charge and size, was used as a window into alterations in gene expression and a means to compare the macrophages carrying a resistant allele of Nramp1 gene and/or normal allele of Lps gene, with their counterparts carrying either a susceptible allele of Nramp1 or defective allele of the Lps gene. We demonstrate that the changes of constitutive levels of two proteins named according to their isoelectric point/molecular weight (pI/Mr), p6.6/25 and p7.0/22, discriminate satisfactorily not only the macrophages congenic at the Nramp1 gene but also the macrophages congenic at the Lps gene, thus reflecting their common genotype (Nramp1r, Lps[n]). Furthermore, the decreased constitutive levels of these proteins in macrophages carrying a defective allele of Lps but preserving a resistant allele of Nramp1 can be, at least in part, restored by stimulation with interferon gamma or lipopolysaccharide. 2-DE immunoblot analysis identified the p7.0/22 protein as manganese superoxide dismutase. Bcl-2 appears to be the best candidate for p6.6/25 as suggested by 2-DE quantitative alterations and Western blot analysis. These proteins are important in the regulation of intracellular redox balance and the regulation of apoptosis in macrophages and their alterations might reflect closely the transport functions of ions or other charged substrates suggested for Nramp1 protein.

Amino Acid Sequence↗
PubMed1996

The immune response against Francisella tularensis live vaccine strain in Lps(n) and Lps(d) mice.

The impact of Lps gene on the course of immune response against subcutaneous infection of mice with Francisella tularensis live vaccine strain was studied. Production and specificity of antibodies, cytotoxic responses of macrophages and NK-cells, spontaneous production ex vivo of cytokines IL-1 alpha, IL-2, IL-4, IL-6, IL-10, IFN-gamma, and TNF-alpha in spleen cell cultures in C3H/HeJ (Lps(d)) mice in comparison with C3H/HeN (Lps(n)) mice were tested. The value of LD(50) was significantly different in the two strains of mice (8.0 x 10(5) cfu for C3H/HeJ versus 4.61 x 10(3) cfu for C3H/HeJ mice after subcutaneous inoculation). The production of NO(2) is also impaired in C3H/HeJ mice in the early intervals after infection. Thus, the defective Lps gene of C3H/HeJ mice influences both the level of innate resistance of mice to F. tularensis live vaccine strain infection and the process of induction and regulation of immune response against this intracellular bacterial pathogen.

Animals↗
PubMed1991

[Modulatory effect of glucans on the function of murine macrophages, NK-cells and lymphocytes].

The particulate glucan (G1), soluble glucan preparations (G2 to G5, and G7) isolated from Saccharomyces cerevisiae, and glucomanan prepared from culture fluid after cultivation of Candida utilis (G6) were tested for their immunomodulatory activity in vivo and in vitro. In tests in vivo three soluble glucans (G3, G4, and G7) injected s.c. to mice in the dose of 10 mg/kg increased the cytotoxic activity of peritoneal macrophages. The influence of glucans on natural killer cells was without significance. The lymphoproliferative reaction of spleen cells to polyclonal mitogens was inhibited by all the preparations used with the exception of soluble glucan G2. The mitogenic effect of the preparations, co-stimulatory tests and direct cytotoxicity to cells of cell lines used in cytotoxicity assays were assessed in vitro. The transformation index of glucans in the study was increased according to the glucan and dose tested. Inhibition of the lymphoproliferative reaction measured by the co-stimulatory test for optimal concentration of Concanavalin A occurred in a wide range of doses for the preparations G1 to G6. The preparation G7 increased the incorporation of 3HTdR under the same conditions. The use of a suboptimal concentration of Concanavalin A revealed co-stimulatory activity of all the preparations tested. Assessment of the cytotoxic activity of peritoneal macrophages and of the activity of natural killer cells induced in vitro was complicated by the direct cytotoxicity of particulate glucan and soluble glucan G5 (carboxymethylglucan) for target cells (YAC 1, and YAC 1 and K 562 resp.).

Adjuvants, Immunologic↗
PubMed1990

The production of oxygen metabolites and their possible regulatory role in the course of tularemia infection.

The changes of oxidative metabolism were studied in the course of a primary infection of mice with attenuated strain of Francisella tularensis. Metabolic stimulation of peritoneal cells is associated with a significant increase in spontaneous tetrazolium derivative reduction, the production of superoxide anion and hydrogen peroxide on day 5 after the immunization. The enhancement of superoxide dismutase precedes the increase in superoxide anion secretion. The splenic cells of immunized mice obtained on day 3 and in vitro pulsed by tularemic antigen secreted lymphokins(s) that could induce a metabolic stimulation. The treatment of resting splenic cells with hydrogen peroxide induces the secretion of interferon activity. The changes of oxidative metabolism that appear early after the infection seem to be related to a sequential activation of cells and probably have a regulatory role in the induction of immune defence against F. tularensis.

Animals↗
PubMed1990

The activation of macrophages in the immune response against the intracellular bacterial pathogen Francisella tularensis.

The activation of peritoneal macrophages in the course of primary infection of mice with attenuated strain of Francisella tularensis is associated with 2.5 fold increase in spontaneous INT reductase activity on day 5 after the immunization. The splenic cells of immunized mice pulsed in vitro by specific antigen secrete lymphokine that is able to induce an increase in spontaneous INT reductase activity of resident peritoneal cells. The production of spontaneous superoxide anion by peritoneal phagocytes reaches the highest level on day 5 after the immunization. It does not correlate with the results of cytotoxic or phagocytic activities at this time interval. An enhanced superoxide dismutase activity precedes an increase of superoxide anion secretion. The production of hydrogen peroxide is rising till day 7 and is related to the cytotoxic activity of peritoneal phagocytes. Concerning the testing of F. tularensis antigen as immunization agent, no changes of oxidative metabolism were detected. This might be in connection with the insufficient protection effect of killed F. tularensis vaccine. The production of reactive oxygen metabolites, probably under the control of superoxide dismutase, together with secreted lymphokines during the first days after the infection may play a regulatory role in the induction of immune response against intracellular pathogen F. tularensis.

Animals↗
PubMed1989

Protein heterogeneity of Francisella tularensis: detection of proteins with antigenic determinants.

The autolyzates of three different strains of Francisella tularensis 15L, 130 and SCHU were tested for their immunogenic potential and protein heterogeneity. The autolyzates induce the production of specific antibodies, the delayed type of hypersensitivity, and some degree of protection against European virulent strain 130. This material (as antigen) was especially suitable for ELISA. When the autolyzates were subjected to SDS gradient PAGE, a variety of polypeptides were distinguished. The composition of polypeptides from all three strains on SDS-PAGE was almost identical. After the detection of antigenic determinants by Western blotting more than twenty bands appeared. The visualization with polyclonal antisera against live laboratory strain 15L and against autolyzates 15L, 130 and SCHU revealed differences in the composition of the antigenic determinants of these strains.

Animals↗
PubMed1989

[Interleukin 2. Biochemical aspects of structure and function. Review].

During the last several years, the important progress has been achieved in studying activation and proliferation processes altogether with differentiation of mononuclear cells and regulatory course of immune response. In addition to molecular biology, also the biochemical characterization of interleukins, mainly Interleukin 2 (IL 2), is of a substantial import. IL 2 is actionning as an amplificator of T and B immune cellular reactions, and it influences the production of lymphokines, i.e., gamma interferon as well as participates in antitumorous immunity. IL 2 belongs to the range of products being secreted by T lymphocytes following the specific antigenic or polyclonal mitogenic simulation of cells. It can be classed as a growth factor of cells and regulatory factor of immune responsiveness. The human IL 2 was isolated as a protein with Mr 16 kD. On the basis of complementary DNA, the molecular weight has been determined for IL 2 as 15.4 kD. The IL 2-related human gen is localized on 4th chromosome and the product of the respective gen is a protein composed of 133 amino acids. This very protein undergoes glycosylation on the 3d position having alpha-helicoid conformation. The murine IL 2 occurs rather as a dimer composed of two protein chains with Mr 16-18 kD. Variable degrees of glycosylation involve the heterogeneity and pI differences in isolated forms of IL 2. Actions of IL2 are triggered by its interaction with specific receptor, which appears on the T cells no sooner as they are activated by the antigen or mitogen. Following the IL 2 with receptor interaction, the hydrolysis of phosphatidylinositolphosphate occurs intracellularly as well as activation of proteinkinase C and a track of other biochemical reactions non-elucidated till now, which lead up to the transcription regulation of genes and transfer of mitotic apparatus from G1 into S phase of cellular cycle and of division of cells.

Animals↗
PubMed1989

Multistep scheme for testing immunomodulatory substances.

The presented multistep program for testing immunomodulatory properties of biological response modifiers offers the possibility to evaluate multilaterally the modulatory potential of the tested preparations and to obtain basic data concerning their acute immunotoxicity. The scheme is divided into four stages: screening, optimalization, modelling, and analytical stage, each of which can be carried out separately on a relatively individual basis. This division considers the effect of the preparation on basic functions of the cells participating in the network of immunoregulation, the influence on the course of the immune response, modulation of the reactivity of the immune system affected by a 'non-immunological' phenomenon, as well as changes in protein repertoire produced by different systems of cells exposed to the tested preparation and/or the immunogenic signal. Detailed toxicological evaluation should be performed separately from immunopharmacological evaluation, keeping in mind differences in the application of the substances and the animal model involved. Incorporation of mathematical modelling and computer analysis of the results obtained by using the scheme may prove valuable in solving problems associated with potential modulation of the host immune system in clinically significant situations.

Adjuvants, Immunologic↗
PubMed1982

[Resistance to the Venezuelan equine encephalomyelitis virus in immunization with live tularemia vaccine].

Guinea pigs immunized with live tularemia vaccine have been found to possess pronounced resistance to Venezuelan equine encephalomyelitis virus infection. Antiviral resistance induced by the vaccine has been found to persist for 1 month. One of the possible mechanisms, though not the only one, of this resistance is the stimulation of macrophages by tularemia vaccine, which results in the enhancement of their resistance to the cytotoxic action of the virus.

Animals↗
PubMedDate not supplied

The analysis of S100A9 and S100A8 expression in matched sets of macroscopically normal colon mucosa and colorectal carcinoma: the S100A9 and S100A8 positive cells underlie and invade tumor mass.

The expression of calcium-binding protein S100A9 was investigated in 23 matched sets of colorectal carcinoma and normal colon mucosa using two-dimensional gel electrophoresis. We found that, from a group of 23 patients, the level of S100A9 protein, in comparison with matched normal colon mucosa, was significantly increased in malignant tissues of 16 patients (70%). Furthermore, an additional protein, identified by matrix-assisted laser desorption/ionization - mass spectrometry (MALDI-MS) as S100A8, exhibited an increased expression in the same specimens of malignant tissues as the S100A9 protein. The immunohistological analysis revealed the accumulation of S100A9 positive cells, macrophages and polymorphonuclear leukocytes along the invasive margin of colorectal carcinoma. The S100A8 protein was found to be produced in the same location. The possible participation of both proteins and, especially, its heterodimeric complex calprotectin in colorectal carcinoma regression could be taken into account.

Antigens, CD↗