Biomedical subjects

A Dujić

Publications and source records attributed to A Dujić.

At least 19 recordsLinked to original sources

PubMed1998

A dental implant: aluminium trioxide exhibited no effect on mouse reproductive and mutanogenic potential.

Several diseases as well as trauma can affect the composition and integrity of periodontal tissues leading eventually to the destruction of connective tissue matrix and cells, loss of attachment and resorption of alveolar bone, often followed by tooth loss. Replacement of the missing tooth could then be provided by endosseous dental implants healing in a form of osseo- or fibrosteal integration to the alveolar bone. Aluminium oxide ceramics, a form of endosseous implant, allows osseointegration type of healing and has demonstrated excellent biocompatibility. However, potential aluminium toxicity has been implicated in the pathogenesis of a number of clinical disorders and for this reason we examined the reproductive and mutagenic effect of aluminium trioxide ceramic implant in experimental mice. 720 female and 45 fertile male BALB-cAn NCR mice were included in the study. 3 experimental groups of fertile male mice (15 for each group) were treated with an intraperitoneal injection of aluminium trioxide (1 g/ kg of body weight, group I), with ethyl-methane-sulphonate as a positive control (200 mg/kg, group II) and with Tween-80 (10 mg/kg as a negative control, Group III). Each of the labeled male mice fertilized previously uncoupled female mice during 8 weeks (a pair per week) to facilitate appropriate pre- and post-meiotic conditions of spermatogenesis to occur. Female mice were sacrificed with cervical dislocation at day 13 after fertilization. Immediately upon sacrifice the uterus was removed and the number of alive and healthy, or alive but mutated and/or dead embryos was computed to determine the dominant lethal or mutagenic effect. Animals treated with aluminium trioxide demonstrated similar effects on the reproductive and mutagenic capacity as the negative control, whereas the animals treated as positive controls exhibited significantly reduced reproductive and mutagenic capacity. Collectively, we concluded that aluminium trioxide has a very low rate of embryonal mortality and mutagenicity in mice. This finding is in general agreement with the biocompatibility of aluminium trioxide as an implant material.

Aluminum Oxide↗

PubMed1998

Bidirectional interactions between thymocytes and thymic epithelial cell lines in vitro.

In vitro interactions of thymocytes and thymocyte hybridomas with cortical (R-TNC.1) and medullary (TE-R 2.5) rat thymic epithelial-cell (TEC) lines were studied. It was found that the cortical line had better adhesion capability. It bound exclusively immature CD4+ CD8+ alpha beta TCRlo thymocytes, induced apoptosis of a subset of these cells, and stimulated proliferation of the BWRT 1 (CD4- CD8- alpha beta TCR-) hybridoma. The medullary line bound both immature and mature thymocytes, decreased their apoptosis, and induced apoptosis of the BWRT 8 (CD4+ CD8lo alpha beta TCRhi) hybridoma. Thymocyte differently modulated cytokine production by TEC lines, upregulating the secretion of IL-1 by R-TNC.1 and IL-6 by TE-R 2.5 cells. Finally, coculture of thymocytes with TEC lines resulted in different patterns of protein-tyrosine phosphorylation in thymocytes. These results show the existence of mutual bidirectional interactions between thymocytes and TEC lines in vitro, but these processes differed depending on phenotypic characteristics and origin of TEC lines used.

Animals↗

PubMed1995

Aberrant levels of cytokines within the healing wound after burn injury.

OBJECTIVE: To study the effect of a burn injury on the course of cellular and cytokine changes in a wound and the relationship of these cytokines to the amounts of protein and collagen deposited at the site of the wound. DESIGN: A randomized control trial was done in which one group of rats were subjected to a severe burn injury. With the use of a sponge matrix model, the wound-healing parameters were evaluated. MATERIALS: A random sample of eight inbred albino Oxford rats per group were used in all experiments. INTERVENTIONS: Rats were subjected to a severe scald injury. Polyvinyl sponges were used as the wound-healing model. MAIN OUTCOME MEASURE: The obtained results implied that the wound-healing process is impaired after a severe burn injury. RESULTS: The wounds in these animals with burn injuries contained a lower number and an altered type of infiltrating cells with aberrant levels of cytokines, higher levels of interleukin-6, and lower levels of tumor necrosis factor and interleukin-1 in the fluids of the wounds. The parameters of healing (amounts of protein and collagen deposited at the site of the wound) were significantly lower in animals with burn injuries on days 7 and 14. CONCLUSION: The underlying mechanism of the impaired healing of a wound after burn injury could lie in the altered migration of inflammatory cells to the site of the wound and in the aberrant cytokine levels within the wound.

Animals↗

PubMed1994

A novel anti-rat CD18 monoclonal antibody triggers lymphocyte homotypic aggregation and granulocyte adhesion to plastic: different intracellular signaling pathways in resting versus activated thymocytes.

We have raised a monoclonal antibody (mAb), NG2B12, directed against rat CD18, capable of inducing lymphocyte homotypic adhesion and granulocyte adherence to plastic. NG2B12-induced aggregation is temperature sensitive and requires metabolic energy, an intact cytoskeleton and the presence of Mg2+, but is independent of protein synthesis. Ca2+ is not only dispensable but exerts a suppressive effect on the NG2B12-induced adhesion. The adhesion is readily observed in thymocytes and concanavalin A blasts of thymocytes and splenocytes but is very weak in resting spleen and lymph node cells. NG2B12 also enhances phorbol 12-myristate 13-acetate (PMA)-induced aggregation in an additive fashion. The NG2B12-induced homotypic adhesion is mediated by LFA-1. mAb against ICAM-1 completely inhibited the induced adhesion of activated cells but inhibited only partially and in a time-dependent manner the adhesion of resting thymocytes. The activation of protein phosphatases 1 and 2A (as assessed by the use of okadaic acid) is necessary for the NG2B12-induced adhesion of both resting and activated thymocytes. In contrast, H-7 (an inhibitor of protein kinase C and A), substantially suppressed the adhesion of resting thymocytes, whereas W-7 (an inhibitor of calmodulin-dependent protein kinase) inhibited the adhesion of activated thymocytes. NG2B12 induces both adherence to plastic and homotypic aggregation of granulocytes; the events being blocked by anti-CD18 (WT.3) and anti-CD11b/CD11c (OX-42) mAb, augmented by okadaic acid and not modified by H-7 and W-7. Additionally, we have demonstrated that NG2B12 and PMA employ distinct intracellular signaling pathways in inducing adhesion of both thymocytes and granulocytes.

Animals↗

PubMed1994

Post-traumatic activation of draining lymph node cells. II. Proliferative and phenotypic characteristics.

Proliferative and phenotypic characteristics of cells in regional lymph nodes that drain burn injury were examined in rats on day 3 postburn, i.e. at the time of maximal spontaneous proliferation and of interleukin-2 and accessory cytokine (IL-1 and IL-6) production. The importance of IL-1 in spontaneous proliferation of draining lymph node cells was demonstrated by stimulation of IL-2-driven proliferation by recombinant IL-1 in vitro and by susceptibility of unstimulated proliferation to anti-IL-1 antibodies, while requirements for IL-6 in draining lymph node cell proliferation were less pronounced. Cell surface phenotyping revealed a slightly increased percentage of CD25+ cells in the blast cell population of freshly isolated draining lymph node cells after injury, which increased further during cultivation. Enrichment in CD8+ cells on day 3 following burn injury was demonstrated, while no changes in total cell population and CD4+ cells was noted. This was however preceded by pronounced percentual decrease of total T cells and CD4+ cells and by increases of B cells and MHC class II+ cells on day 1 postburn. Inhibition of draining lymph node cell proliferation by anti-MHC class II antibodies suggested that this proliferation was class II MHC dependent. The contribution of cell proliferation and/or cell influx to day 3 postburn draining lymph node cell activity is discussed.

Animals↗

PubMed1994

An adhesion-promoting anti-rat CD18 monoclonal antibody differentially alters thymocyte responses to various mitogens.

Leukocyte function-associated antigen (LFA)-1 represents one of the major lymphocyte adhesion molecules being capable of both strengthening cell-cell contacts and cooperating with other relevant surface molecules in signal transduction. We have studied the effects of an adhesion-promoting anti-CD18 monoclonal antibody (mAb) (NG2B12) on thymocyte proliferation induced by various mitogens. As we have recently described, the adhesion-promoting function of this mAb strictly depends upon the activation of several intracellular protein kinases and phosphatases. In the present work we have found that NG2B12 inhibits concanavalin (Con) A-induced thymocyte proliferation suppressing IL-2 production by these cells. Conversely, this mAb enhances proliferative responses of thymocytes to phytohemagglutinin (PHA) and interleukin (IL)2 alone or in combination with the phorbol ester PMA. The effects of this mAb were compared with those of another anti-rat CD18 mAb which potently blocks the LFA-1/Intercellular adhesion molecules (ICAMs) interactions.

Animals↗

PubMed1994

Adhesion molecules involved in the binding and subsequent engulfment of thymocytes by a rat thymic epithelial cell line.

A rat thymic epithelial cell (TEC) line (R-TNC.1) was established from a long-term TEC culture. Based on its ultrastructure, phenotype and cytokeratin profile, this line was characterized as a type of cortical TEC. R-TNC.1 cells had nursing activity which was manifested by the binding and subsequent engulfment of thymocytes. The role of adhesion molecules involved in these processes was studied extensively using a coculture of resting thymocytes and unstimulated or interferon-gamma (IFN-gamma)-stimulated R-TNC.1 cells. It was found that a number of adhesion molecules, such as CD2, CD4, CD8, LFA-1, CD18, ICAM-1 and Thy-1, was partly involved in the nursing activity. The effect of monoclonal antibodies (mAb) to these molecules depended on the incubation time and stimulation of R-TNC.1 cells. The inhibitory effect of mAb to CD2, LFA-1, CD18 and ICAM-1 on thymocyte engulfment was higher than their effect on thymocyte binding to the R-TNC.1 line. In addition, a LFA-1/CD18-dependent/ICAM-1-independent adhesion pathway was identified when unstimulated R-TNC.1 cells with minimal expression of ICAM-1 were used. The combination of inhibitory mAb did not completely abrogate the nursing activity of the R-TNC.1 line, suggesting the possible involvement of some other adhesion molecules.

Animals↗

PubMed1993

Prevalence of G-to-T transversions among K-ras oncogene mutations in human colorectal tumors in Yugoslavia.

Human colorectal carcinoma tissue sampled from 37 patients, routinely graded into Dukes' stages A, B and C and histologically examined for the level of differentiation, were analyzed for the presence of point mutations in the K-ras oncogene. Seventeen cases out of the 37 analyzed were found to have a mutation in either the 12th or the 13th codon of the K-ras gene, giving an overall frequency of mutation of 46%. The incidence of mutations in Dukes' stages A, B and C was 33, 46 and 58% respectively. Although the frequency of mutation appears to be similar to that reported for the USA population, the spectrum of point mutations in codons 12 and 13 of the K-ras gene in the Yugoslav population appears to differ significantly. G-to-T transversions make up 77% of all mutations present, with the distribution as follows: 18% at the first base and 59% at the second base of codons 12 and 13. G-to-A transitions at the second base is the only other mutation identified, occurring mainly in codon 13 in colorectal tumors of all 3 stages.

Adult↗

PubMed1993

Two novel monoclonal antibodies reactive with different components of the rat thymic epithelium.

Two novel monoclonal antibodies (mAbs) (PT10B7 and PT13D11) have been raised against molecules of rat thymic epithelial cells (TEC). Streptavidin-biotin immunoperoxidase staining and double immunofluorescence using these mAbs and anti-cytokeratin (CK) antibodies showed that PT10B7 and PT13D11 mAbs bound to different components of rat TEC. PT10B7 mAb reacted with cortical and a subset of medullary TEC, whereas PT13D11 mAb labeled subcapsular/perivascular and most medullary TEC, including TE-R 2.5 TEC line of medullary origin. Their staining patterns were different from those seen using mAbs to CK10, CK18 and CK19 polypeptides and other anti-rat TEC mAbs produced so far. The differences in immunoreactivity of these two mAbs on rat thymus during ontogeny and on other epithelial cells of adult rats were also seen. Namely, PT13D11 stained ectoderm-derived epithelia, whereas PT10B7 stained some cells of simple epithelia. Cumulatively, these results reveal a fine phenotypic heterogeneity within rat thymic epithelium.

Animals↗

PubMed1992

Interferon gamma alters the phenotype of rat thymic epithelial cells in culture and increases interleukin-6 production.

Rat thymic epithelial cells (TEC) in long-term culture were characterized by anticytokeratin monoclonal antibodies (mAbs) and electron microscopy. Phenotypic analysis performed by a large panel of mAbs showed that the highest percentage of these cells was of the subcapsular/medullary type. Recombinant rat interferon (IFN)-gamma up-regulated class-I and class-II MHC expression by TEC in culture as confirmed by immunohistochemistry and flow cytometry, but did not significantly alter other cell markers. TEC supernatants of IFN-gamma-treated cultures showed higher interleukin-6 (IL-6) activity, compared to the control, as determined by proliferation of the IL-6-sensitive B9-cell line. Increased IL-6 activity was probably not a consequence of increased TEC number in IFN-gamma-treated cultures because IFN did not significantly stimulate TEC proliferation in vitro. In contrast, IL-6 significantly stimulated TEC proliferation, indicating that this cytokine is not only a regulatory molecule for T-cell proliferation, but could also be an autocrine growth factor for thymic epithelium.

Animals↗

PubMed1992

Phenotypic and ultrastructural characterization of an epithelial cell line established from rat thymic cultures.

An epithelial cell line (TE-R 2.5) was established from a long-term culture of rat thymic epithelium. Its epithelial nature was confirmed using anti-cytokeratin (CK) monoclonal antibodies (mAb) and electron-microscopy. TE-R 2.5 cells were reactive with K 8.13, K 8.12, CK 8, R-MC 18, R-MC 19 and Mar 3 mAb and bind Ulex europaeus agglutinin I. Based on the results of this study it was concluded that they possess the phenotype of subcapsular/perivascular or medullary epithelium. This was in accordance with Western blot analysis of water-insoluble cell extracts showing the presence of 56,000, 52,000, 50,000 and 48,000 MW CK polypeptides. In addition, TE-R 2.5 cell line coexpressed CK and vimentin (a 57,000 MW polypeptide) which was demonstrated using dual immunohistochemistry and Western blot analysis. Electron microscopy demonstrated that TE-R 2.5 cells have all the characteristics of hypertrophic thymic epithelial cells (TEC) localized in situ exclusively in the medulla and thus further characterized this line as a type of medullary TEC. Finally, TE-4F10 mAb raised against an antigen of TE-R 2.5 cells selectively stained a subset of medullary TEC in situ including Hassall's corpuscles indicating again the medullary origin of this TEC line.

Animals↗

PubMed1991

Rat thymic epithelial cells in culture constitutively secrete IL-1 and IL-6.

To study the in vitro interactions between rat thymic non-lymphoid cells and thymocytes, we established a system for long-term cultivation of thymic epithelial cells (TEC). TEC were cultivated and successfully propagated for over 8 months in RPMI 1640 medium containing 15% FCS, dexamethasone, insulin, epidermal growth factor, and poly-L-lysin as an adhesive matrix. Their epithelial nature has been confirmed using monoclonal anti-cytokeratin (CK) antibodies. More than 95% of these cells were reactive with K 8.13 and CK 8 mAbs, which are pan-epithelial markers for rat TEC in situ. An epithelial cell clone (TE-R 2.5) established from a long-term TEC culture was 100% reactive with these anti-CK antibodies. Phenotypic analysis of TEC cultures was performed by a large panel of mAbs reactive with a subset of rat TEC or CK polypeptides as well as UIex europaeus agglutinin I using a streptavidin-biotin immunofluorescence assay. Although the results obtained demonstrated phenotypic heterogeneity among these cells, most cultures, including the TE-R 2.5 clone, were of subcapsular/medullary phenotype. Medium conditioned by TEC cultures exhibited IL-1 and IL-6 activities when tested on D10S and B9 sensitive cell lines, respectively. Cytokine activities were neutralized (IL-1) or significantly inhibited (IL-6) by specific polyclonal antibodies. In addition, both anti-IL-1 and anti-IL-6 antibodies reacted with TEC in culture and epithelial (CK-positive) cells on thymic cryostat sections, indicating that thymic epithelium provides an important intrathymic source for molecules contributing to T cell activation.

Animals↗

PubMed1991

Primary culture of rat thymic non-lymphoid cells: influence of culture time on the expression of macrophage differentiation antigens defined by monoclonal antibodies.

A panel monoclonal antibodies (mAbs) raised to rat thymic non-lymphoid cells has been shown to discriminate between distinct subpopulations of macrophages depending on their anatomic localization in the thymus. These reagents were used in this study to examine the expression of macrophage-associated antigens in primary culture of rat thymic stromal cells. The phenotype of both adherent macrophage (AM) monolayers and non-adherent cells (NAC) released in culture medium was studied at different time points after cultivation. More than 95% AM expressed ED1 and R-MC 38 antigens (pan-macrophage markers), class I MHC antigens (OX-18) and iC3b receptor recognized by OX-42 mAb. Most of them (70-85%) were reactive with ED2, R-MC 40, 41 and 42 mAbs specific for cortical and cortico-medullary zone (CMZ) macrophages. A much smaller percentage was positive with R-MC 43/44 and R-MC 46/47 mAbs staining CMZ/medullary macrophages and a subset of cortical macrophages, respectively. A minor subset of AM expressed class II MHC molecules which progressively decreased during cultivation. NAC were phenotypically heterogeneous. In comparison with adherent cells they contained a lower percentage of cortical/CMZ phenotype macrophages. In addition, NAC were slightly enriched in R-MC 43+ cells and more significantly expressed IA/E antigens (85-95%). ED3, R-MC 39 and 45 mAbs reactive with thymic macrophages in situ were mostly non-reactive with AM and NAC in culture.

Animals↗

PubMed1990

Interspecies differences in expression of cytokeratin polypeptides within thymic epithelium: a comparative immunohistochemical study.

Cytokeratin (CK) polypeptide expression within the thymic epithelium of several mammalian species (mouse, rat, calf, pig, rabbit, and human) has been analyzed by the streptavidin-biotin immunoperoxidase method. Comparative analysis by a large panel of 17 monoclonal antibodies (mAbs) specific for individual CK polypeptides, pairs, or groups showed considerable heterogeneity of thymic epithelial cells (TEC) in each species. In addition, extreme interspecies difference in CK contents was observed. Four main phenotypic zones: the subcapsule/perivascular area, cortex, medulla, and Hassall's corpuscles (HC) were clearly identified, each characterized by different CK expression. Medullary TEC were more heterogenous and shared common CK polypeptides either with subcapsular/perivascular TEC, cortical TEC, or HC, in most species.

Animals↗

PubMed1990

Ontogeny of rat thymic epithelium defined by monoclonal anticytokeratin antibodies.

Ontogenetic study on the expression of cytokeratin (CK) polypeptides within particular subsets of rat thymic epithelial cells (TEC) has been performed by a large panel of anti-CK monoclonal antibodies (mAbs) using the streptavidin-biotin immunoperoxidase method. Simultaneous presence of two or more CK subunits in the same TEC has been demonstrated by double immunofluorescence labeling. The obtained results showed that the expression of CK polypeptides in fetal and neonatal thymus differed from the adult patterns. The main difference was observed in expression of CK10, 18, and 19 polypeptides. During fetal ontogeny, CK10 and 18 are markers for most medullary TEC or a subset of medullary TEC, respectively, whereas CK19 is mainly a pan-TEC marker. In the adult animals, they are localized in the cortical and a subset of medullary TEC (CK18), subcapsular/perivascular and some medullary TEC (CK19), or in a subset of medullary TEC and Hasall's corpuscles (HC) (CK10). The switch in their expression in the cortex was observed during the first two weeks of postnatal life.

Animals↗

PubMed1990

[Immunomodulation during viral infections].

The paper provides a survey of immunomodulation mechanisms in the course of viral infections. The importance of viruses in the disturbance of immunological homeostasis has been pointed out. Virally induced immunomodulation can arise by: a mechanism of complete or abortive viral replication in the lymphocytes and macrophages, by soluble viral factors, by the influencing of antigen-presenting cells, and by excessive suppressor T-lymphocyte stimulation. Viral infections present a real danger to the integrity of the immunological system, and this demands a follow-up and an adequate interpretation of the arisen disorders.

Humans↗

PubMed1990

Immunohistochemical characterization of rat thymic non-lymphoid cells. II. Macrophages and granulocytes defined by monoclonal antibodies.

A panel of monoclonal antibodies (mAb) raised to antigens of rat thymic non-lymphoid cells (predominantly macrophages and granulocytes) was immunohistochemically characterized. Based on their staining patterns on cryostat thymic sections and double labellings using acid phosphatase activity, anti-cytokeratin mAb to exclude binding to epithelium or ED1 and ED2 mAb, specific for rat macrophages, antibodies were subdivided into four groups: (i) R-MC 39 mAb strongly reactive with macrophages in the cortex and cortico-medullary zone (CMZ) and weakly with some scattered macrophages in the medulla, blood vessels and thymocytes; (ii) R-MC 40, 41 and 42 mAb specific for cortical macrophages and most CMZ macrophages; (iii) R-MC 43 and 44 mAb predominantly recognizing CMZ and medullary macrophages; (iv) R-MC 45 mAb strongly labelling granulocytes and weakly a subset of macrophages throughout the thymus and isolated cells in the medulla. The obtained results show considerable heterogeneity within mobile thymic non-lymphoid cells and the presence of specific or common antigens in macrophages of particular topographic localization in the rat thymus.

Animals↗

PubMed1990

Genetic basis of resistance to trauma in inbred strains of mice.

In this study the resistance to mechanical, thermal, and radiation trauma in four inbred strains of mice (AKR, BALB/c, CBA, and C57Bl/6) was compared with the degree of genetic resemblance, by analyzing the allozyme variabilities of these strains. It was shown that the highest degree of genetic resemblance was among CBA and AKR strains, which correlated with a similar degree of resistance to trauma. On the other hand, BALB/c and C57Bl/6 strains expressed significant differences, both genetically and with respect to the responses to trauma. The hypothesis is introduced that the genetic determination of the resistance to trauma is based on: a) a polygenic control of general physiological homeostasis, with the possibility that b) some specific genes or single loci may contribute more than others to such adaptations of the strains tested.

Alleles↗