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Biomedical subjects

G Görög

Publications and source records attributed to G Görög.

8 recordsLinked to original sources
PubMed2001

Developing an expert system for immunophenotypical diagnosis in immunodeficiency. Age-related reference values of peripheral blood lymphocyte subpopulations in Hungary.

In the process of developing a decision support system based on flow cytometric data for the diagnosis of immunodeficiency, assessment of lymphocyte subpopulations in human peripheral blood provides the key for further analysis. Samples from 273 'healthy' Hungarian subjects were measured between 1998 and 1999. Immunophenotypic data are compared here (unadjusted for gender) by different age groups: I 0-6 years (n=45); II 7-18 years (n=71); III 19-35 years (n=72); IV 36-55 years (n=48); and V 56-99 years (n=37). Two-color flow cytometric analysis was performed using the Becton Dickinson Simultest IMK Plus kit (CD45/CD14, isotype control, CD3/CD19, CD4/CD8, CD3/HLA-DR, CD3/CD16+56). All lymphocyte subpopulations were measured in all blood samples identically. The quality criteria involved at least 95% of total lymphocytes in the analysis gate, homogenous CD45+ lymphocyte population (minimum of 2000 events in the gate, CD45+ >95%). The frequency of B lymphocytes was the highest, significantly, in the youngest Hungarian subjects, but there were no significant changes with age comparing the data of other II-V age groups. On the other hand, some T subpopulations changed with aging; both CD4 and CD8 subsets varied over time including the elevation of the fraction of activated T cells as well as LGL-NK cells. Some of these changes were significant by statistical tests. Interpretation of flow cytometric data is time-consuming and requires human knowledge of an expert laboratory staff. To facilitate the diagnosis of immunodeficiency, a pilot study aiming at the development of a diagnostic algorithm has been initiated. Algorithm nodes compare the frequency of each lymphocyte subpopulations to the generated reference values. This knowledge-based system describes a short summary report as a result of the comparison, and points to some values requiring further human examination to reach a final conclusion. These reference values and the expert system appear to be a recommended basis for comparing and combining results from different laboratories.

Adolescent↗
PubMed1994

An Excel program for calculating and plotting receiver-operator characteristic (ROC) curves, histograms and descriptive statistics.

Receiver-operator characteristic (ROC) curves have been used increasingly to assess the performance of clinical laboratory tests and to determine suitable positive/negative threshold values. The Microsoft Excel 4.0 program Plot.ROC was designed to provide formatted, publication quality output with minimal user involvement. It asks for a few parameters at the beginning and then runs autonomously, creating ROC charts, histograms and descriptive statistics for each test chosen, and a cumulative ROC chart to compare tests. Output can easily be formatted further using Excel's graphics and text formatting capabilities.

Biomarkers, Tumor↗
PubMed1989

Use of bispecific hybrid antibodies for the development of a homogeneous enzyme immunoassay.

Hybrid bispecific monoclonal antibodies reacting with carcinoembryonal antigen (CEA) and with the E. coli enzyme beta-galactosidase (GZ) were produced by fusion of hybridomas or chemical linkage of half-antibodies. Since the original anti-GZ antibody used in these experiments was capable of protecting GZ from thermal denaturation, it was possible, by hybridizing it with two different non-competitive anti-CEA antibodies, to design a homogeneous enzyme immunoassay for quantitation of CEA. In fact, a mathematical analysis of the reaction indicates that, under appropriate concentrations of the reactants, circular complexes can be formed which contain the two hybrid antibodies, the GZ enzyme and the CEA antigen. The stability of these complexes can be expected to be substantially greater than that of the more labile CEA-free GZ-antibody complexes, prompting a significant increase in the amount of enzyme molecules which are bound to antibody and are consequently protected from thermal denaturation. These expectations were supported by experimental results: under appropriate conditions, heat-resistant enzyme activity was indeed proportional to concentration of CEA in the range up to 75 ng/ml. As predicted by theory, however, in the presence of excess CEA - in fact at CEA concentrations which are higher than those of possible clinical relevance - circular complexes tended to open up, leading to a marked prozone effect.

Antibodies, Monoclonal↗
PubMed1989

Inhibition of the CD3-mediated calcium signal by protein kinase C activators in human T (Jurkat) lymphoblastoid cells.

The changes in the cytoplasmic free calcium concentrations (Cai) were investigated in human T (Jurkat) lymphoblastoid cells, loaded with the calcium-sensitive fluorescent dye Indo-1. A rapid increase in Cai could be evoked by monoclonal antibodies (mAb) directed against the CD3 antigen, as well as by the mitogenic lectin concanavalin A (conA). The protein kinase C (pKC) activators TPA and DiC8 did not increase Cai, but the addition of any of these two compounds prior to mAb eliminated the mAb-induced calcium signal. In contrast, the calcium signal evoked by ConA was not blocked by TPA or DiC8. These results suggest that the CD3-dependent calcium signal is selectively down-regulated by the activation of pKC.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1986

Regulatory function of cell surface molecules CD2-, LFA- and beta 2-microglobulin in natural killer cell activity.

The functional importance of various cell membrane bound molecules was studied and compared in the NK cytotoxicity and CTL activity. LFA-1 and CD2 participate in both killing functions, while CD3 and CD8/CD4 as well as MHC class I molecules are involved only in CTL activity. Nevertheless CD2- and beta 2-microglobulin are representatives of the NK function. It was demonstrated that CD2-, LFA-1 and beta 2-microglobulin molecules have an additive and complementary function in the killing mechanism. The upregulation of alpha- and gamma-interferons on NK function seems not to be a consequence of the enhanced expression of these molecules on the cell surface induced by IF at the same time.

Antibodies, Monoclonal↗
PubMed1985

Effect of anti-human pan-T monoclonal antibodies on lymphocyte proliferative and cytotoxic functions.

Effects of anti-human pan-T-specific monoclonal antibodies of the Second International Workshop on Human Leucocyte Differentiation Antigens were investigated in a number of lymphocyte functional tests. Monoclonal antibodies blocking antibody-dependent cytotoxicity (ADCC), PWM-induced IL-2 release, or Con A- and PWM-induced lymphocyte proliferation were found among anti-CD2 and CD3 reagents. Inhibition of lectin-dependent cellular cytotoxicity (LDCC) was found as an exclusive effect of anti-CD2 (the sheep red cell receptor) antibodies. Several anti-CD2s blocked natural killer (NK) activity and/or PWM-induced interferon production. These two effects were exerted by antibodies against epitopes on resting T cells but not by those directed to activation epitopes. The inhibitory activity of individual antibodies in the LDCC and NK tests showed a good correlation. Also, PHA-mediated cytotoxicity (LDCC) and proliferation were in good correlation. Concerning anti-CD3 (T3) reagents, some effects were characteristic for the majority of the antibodies in this group. Namely, induction of proliferation, enhancement of IL-2-dependent cell division, IL-2 consumption by antibody-triggered cells, inhibition of mitogen-induced proliferation but not IL-2 and interferon production were observed. None of the CD3-specific reagents exerted all of these effects. In general, no correlation of the effects with immunoglobulin subclass or CD3 subcluster specificity could be found. Further epitope analysis and affinity data may be required to understand the basis of heterogeneity in functional effects of monoclonal antibodies to the CD3 molecule.

Antibodies, Monoclonal↗
PubMed1985

Lectin-dependent cellular cytotoxicity by human lymphocytes is blocked by monoclonal antibodies to the sheep red cell receptor.

Investigating the functional effects of anti-T cell monoclonal antibodies (obtained through the Second International Workshop on Human Leucocyte Differentiation Antigens), antibodies to the sheep red cell receptor (CD2) were found to block lectin-dependent cytotoxicity. Blocking was seen with all anti-CD2 reagents tested regardless of epitope specificity, immunoglobulin subclass or other factors. Antibodies to other T cell differentiation antigens had no effect.

Animals↗