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M Turzová

Publications and source records attributed to M Turzová.

17 recordsLinked to original sources
PubMed2002

Information on heart repolarization changes obtained from body surface ECG potentials.

Possibility to obtain information about local changes of heart repolarization from body surface potentials was studied on a model. Activation-recovery intervals (ARI) in surface ECG leads were tested as indicators of changed repolarization in the underlying myocardium. ECG signals corresponding to activation of myocardium with normal and changed action potential duration were simulated on the surface of a realistic inhomogeneous torso. ARI intervals were derived from all ECG signals and displayed as surface ARI maps. Results suggest that shortening and prolongation of action potentials in anterior myocardial regions can be visible in corresponding areas on surface ARI maps while only prolongation in postero-lateral regions can be observed. Reproducibility of ARI maps was checked on real measurements using 63 and 192 surface ECG leads. Obtained ARI maps exhibited acceptable reproducibility with correlation of 0.73 to 0.87. Based on the model and experimental results it is hoped that ARI maps can give some insight into the myocardium repolarization and help to recognize tissue with changed properties, primarily in heart regions underlying the anterior chest.

Body Surface Potential Mapping↗
PubMed2002

Cardio 7--portable system for high resolution ECG mapping.

One of the main difficulties in using body surface potential mapping (BSPM) techniques is the need of complicated multi-channel measuring system. In this paper practical portable ECG mapping system is introduced. The system consists of a notebook computer and a data acquisition system box connected to the computer by fast IEEE 1284 parallel interface working in ECP mode. Concept of the device enables to extend the basic 134-channel high-resolution multi-channel ECG amplifying unit up to 256 channels. Application software includes measurement and real time monitoring of ECG signals, computation and display of several types of body surface potential maps. System can be connected to hospital information networks and supply them with measured ECG data for advanced processing or central archiving.

Body Surface Potential Mapping↗
PubMed1996

The uniform double layer model and myocardial infarction: forward solution consideration.

The Uniform Double Layer (UDL) model of the cardiac generator is often used for forward simulation of body surface potentials (BSPs). The model also proved to be very useful for the inverse computation of heart activation. However, for the purposes of Myocardial Infarction (MI) modelling mostly the Multiple Dipole (MD) models are used. In our study, the ability of UDL model to represent the activation of the heart with an old MI was examined. The finite element model of the heart was used to simulate electrical activation of the heart with an old MI. Different locations of endocardial MI were used. For each of them three cases were considered according to the scale of the infarcted area: small and medium endocardial and large transmural. For the further computation of the electric field within the torso volume conductor two types of UDL representation of the cardiac generator were used. For the first UDL model, supposing the scared tissue to be unexcitable, an "infarcted" surface (different from the "healthy" surface) of activated myocardium was generated for each case of MI. Times when activation wavefront reached particular nodes on the surface served as an input for the forward computation of BSPs. To be able to understand the behaviour of the UDL, we also created the second UDL model, where the "infarcted activation sequence" was approximated on the original "healthy" heart surface. The BSPs were computed for each case of MI using both UDL cardiac generators. The boundary element method with the inhomogeneous volume conductor was used for computations. The BSPs generated by both models for the same case of MI were compared using the correlation coefficient. The results show, that it is possible to find an approximation of the "infarcted activation sequence" on the "healthy" heart generator surface in a way that BSPs generated by both models have a correlation coefficient higher than 0.96 for the entire period of depolarisation. Visualisation of the epicardial isochrones might help to understand the UDL model behaviour under the MI conditions. It would be useful for the correct interpretation of the results when using the UDL model for inverse solution. (Fig. 7, Ref. 5.)

Body Surface Potential Mapping↗
PubMed1996

Model study of influence of extracardial factors on the inverse localization of preexcitation sites.

Inverse solution techniques are expected to help in noninvasive localization of ventricular preexcitation sites. The influence of selected extracardial factors on the accuracy of the inverse localization of the initial activation sites was studied on a model. Each of 8 simulated activation sequences was initiated in a different single starting point at the atrioventricular ring. Corresponding ecg potentials on the surface of a realistic model of inhomogeneous torso were used for the inverse localization procedure. A multiple dipole (MD) model of the cardiac generator composed of 39 segmental dipoles was used in the inverse computations. As it was shown in a previous study, the method was able to localize the 8 starting points even if a simplified torso model and a limited number of leads was used. In this study, influence of another two factors was evaluated: inaccuracy of location of the MD generator and presence of noise in surface potentials. Several shifts and rotations of the heart generator relative to its exact position were modeled. When the mean deviation of starting points was about 1 cm the mean localization error varied from 0.5 cm up to 1.0 cm for complete model data--198 surface potentials and a torso model including lungs and ventricular cavities. When a noise with uniform and Gaussian distribution was added to the surface potentials, the use of averaged body surface potentials significantly improved accuracy and stability of the inverse solution. For root mean square value of noise sigma = 14 microV the mean error of localization was 0.9 cm. For higher noise (sigma = 30 microV) the results were substantially deteriorated. The influence of a noise was studied on complete model data. (Tab. 3, Fig. 5. Ref. 6.)

Body Surface Potential Mapping↗
PubMed1994

A model study of the sensitivity of body surface potential distribution to variations of electrode placement.

The effect of electrode displacement as one of the sources of reproducibility errors in body surface potential maps was studied using a realistic computer model of the cardiac electric field. A uniform dipole layer model of the cardiac generator and a realistic geometry of the torso, heart, and lungs was adopted for the simulation of surface potentials during ventricular activation. The effect of systematic electrode displacement in terms of longitudinal shifts and variations of longitudinal size (height) of the mapped area was studied. The map reconstruction error of three different limited lead systems and the variability of maps measured on all points of the mapping grid, as well as maps reconstructed from limited lead systems, were investigated and quantified. A mean relative error of map reconstruction of less than 3.5% was found for longitudinal shifts from -4.4 to +1.7 cm, and for longitudinal size changes from 65 to 108% of the initial area. For vertical displacements of electrodes between the limits of +/- 2.0 cm for full grid maps and +/- 1.4 cm if limited lead systems were used, the mean relative error of the maps remained under 5%.

Body Surface Potential Mapping↗
PubMed1993

Modulation of leukosialin (sialophorin, CD43 antigen) on the cell surface of human hematopoietic cell lines induced by cytokins, retinoic acid and 1,25(OH)2-vitamin D3.

Cell surface expression of leukosialin (sialophorin, CD43 antigen) on human neoplastic hematopoietic cell lines K-562, U-937, HL-60 and REH was determined with the aid of a new CD43 monoclonal antibody (Bra7G) by the immunochemical (radioimmunoprecipitation, immunoblotting) and immunocytofluorometric techniques. Interferon-gamma and TNF-alpha were utilized as the "physiological" inducers of differentiation-associated markers. The "non-physiological" inducer phorbol ester PMA induced down-regulation of leukosialin cell surface expression on immature erythroid-myeloid leukemia cell line K-562, but up-regulation of CD43 antigen on the promyelocyte leukemia cell line HL-60 and, to a lesser extent on the monocyte-like U-937 and CALLA+ ALL cell line REH. Retinoic acid down-regulated leukosialin on both U-937 monocyte-like cells and the CALLA+ ALL cell line REH. In contrast to these data, interferon-gamma, TNF-alpha, retinoic acid and 1,25(OH)2-vitamin D3 induced the up-regulation of leukosialin in a promyelocytic leukemia cell line HL-60.

Antigens, CD↗
PubMed1992

Monoclonal antibodies to two adhesive cell surface antigens (CD43 and CD59) with different distribution on hematopoietic and non-hematopoietic tumor cell lines.

Two new murine monoclonal antibodies were prepared by hybridoma technique after immunization with the immature pluripotent leukemia cell line K562. The monoclonal antibody Bra10G (IgG2b) reacted in a non-lineage pattern with all examined hematopoietic neoplastic cell lines and peripheral blood cells (granulocytes, lymphocytes, erythrocytes) of healthy donors, with the exception of monoblastoid cell line U-937 and B lymphoma cell line Daudi. This monoclonal antibody immunoprecipitated an 18-20 kDa cell surface protein expressed also on the cell surface of examined non-hematopoietic (malignant glioma, melanoma and breast carcinoma) cell lines. These properties and the efficient inhibition of Bra10G binding to the cell surface of K562 cells by the reference CD59 monoclonal antibody (MEM-43) indicated that Bra10G belongs to the CD59 cluster of monoclonal antibodies which identify the human protectin molecule. The monoclonal antibody Bra7G (IgM) reacted with a 95 kDa cell surface protein expressed on hematopoietic cells (with the exception of erythrocytes) and was absent on the examined non-hematopoietic neoplastic cell lines. These data together with a partial inhibition of Bra7G binding by the reference CD-43 monoclonal antibody suggested the CD43 (leukosialin, sialophorin) specificity of this monoclonal antibody.

Animals↗
PubMed1992

T-lymphocyte subsets (CD4/CD8 ratio) in breast cancer patients.

T-lymphocyte subsets (CD4/CD8 antigen positive cells) were determined in peripheral lymphocytes from 48 patients with breast cancer of different stages by flow immunocytometry with the aid of anti-CD4 and CD8 monoclonal antibodies. A broad individual variability of the CD4/CD8 ratio among both healthy donors and breast cancer patients was observed. The average value of CD4/CD8 ratio decreased in groups as follows: Healthy donors and Stage I patients, Stage IIA, IIB and Stage IV breast cancer patients. These differences were generally statistically not significant. The difference between healthy donors and Stage IV breast cancer patients was statistically significant (p < 0.01), if one exceedingly elevated value of the CD4/CD8 ratio was excluded from statistical evaluation. The average CD4/CD8 value in the group of breast cancer patients with lymph node or distant metastases was lower than that of patients without metastases, but their difference was not statistically significant either.

Breast Neoplasms↗
PubMed1991

External quality control of mycobacterial laboratories in the Czech and Slovak Federal Republic and in the former German Democratic Republic.

Simulated samples of sputa respectively negative sputa artificially contaminated with mycobacteria were sent to mycobacteriological laboratories in CSFR and the former GDR for the purpose of conducting an external quality control of the process employed in bacteriological examination. The average percentage of positive results corresponding with the reference material came to 75.7% in CSFR and 92.0% in former GDR. Methodological differences influencing the results of external laboratory control in both countries are discussed. Systematic external controls are recommended as an invaluable aid for improvement of the bacteriological demonstration of mycobacterial infections.

Bacteriological Techniques↗
PubMed1991

Human monoblastoid cell line U-937 cultured in protein-free medium: immunophenotype, cytochemical and biochemical markers.

Human monoblastoid cell line U-937 was adapted to grow in protein-free (protein-free hybridoma--PFH) medium and cloned by limiting dilution. Resulting cell subline (U-937/PF) cultured in protein-free medium was characterized by immunological, cytochemical and biochemical techniques. There were no major differences in immunophenotype (determined by FACS analysis with monoclonal antibodies directed to HLA and CD antigens) and cytochemical markers between the U-937/PF cells cultured in protein-free cell culture medium and parental U-937 cell cultured in serum-supplemented medium. Maximal cell density was slightly decreased in protein-free culture as compared to the parental cell line in FCS-supplemented medium. Cell viability and cell DNA histograms (determined by propidium iodide cytofluorimetry) showed no major differences between parental U-937 and U-937/PF cells. Phorbol ester (TPA)-induction of differentiation-associated cell markers resulted in a proliferation arrest and accumulation of G0/G1 cells in both sublines. All-trans retinoic acid and, to a lesser extent, TPA-stimulated NBT reduction was higher in parental U-937 cells cultured in serum-supplemented medium as compared to U-937/PF cells. Quantitative differences in the expression and inducibility of some cytochemical markers (beta-glucuronidase, chloroacetate esterase) were found between both examined sublines. Described U-937/PF subline cultured in a protein-free cell culture medium (PFH) appeared as a potential tool for studies of in vitro inducing agents and serum components with differentiation promoting (or inhibiting) activities.

Acid Phosphatase↗
PubMed1990

[Use of ELISA for the detection of IgG antibodies to Mycobacterium tuberculosis in the diagnosis of tuberculosis].

The presence of mycobacterial antibodies of IgG type was determined in serum, cerebrospinal fluid and pleural puncture fluid by using ELISA and soluble antigens of the strain Mycobacterium tuberculosis H37Rv. In patients suffering from tuberculosis the most frequently found titer was 1:320 and above. This titer was however found also in 30% of healthy subjects of the control group and 29% of patients with other than tuberculous disease. The sensitivity of the test was 0.7692 and its specificity 0.4594. On examining cerebrospinal fluid of patients with suspect tuberculous meningitis, positive titers of 1:640 and 1:1280 were found in two cases, while the titers of all the other patients were definitely negative. In both cases with positive titers there was also a high antibody titer in serum and additionally also culture positivity or positive biological test was evidenced. This combination of examinations allows prompt administration of antituberculous therapy in case of positivity. The results obtained in examining pleural puncture fluid and serum are open to discussion.

Adolescent↗
PubMed1989

[Evaluation of the antimicrobial effect and toxicity of glutaraldehyde].

The antimicrobial efficacy and toxicity of a solution containing 20 g.l-1 glutaraldehyde was evaluated. All the tested germs of gram-negative microorganisms and of the strain Staphylococcus aureus were killed within 5 minutes, those of mycobacteria within 120 minutes, and bacterial spores in the course of 240 minutes. The fungicidal effect of the solution upon the strain Candida albicans became manifest after 10 minute exposure and upon the tested genera of dermatophytes after 30 minute exposure. The bacteriophage phi X 174 was inactivated within 60 minutes. In the view of the obtained values of its antimicrobial efficacy and toxicity, glutaraldehyde is recommended as a chemosterilizing substance.

Aldehydes↗
PubMed1975

[The value of guinea pig inoculation for the detection of tubercle bacilli in the patients specimens (author's transl)].

5912 specimens were examined by culture and animal experiment and the presence of tubercle bacilli was established with one or the other with both methods. An analysis of the results showed, that guinea pig tests in 29.1% of the cases were more accurate than were cultural methods. Experimental inoculation is, therefore, still an essential part of the laboratory diagnosis of tuberculosis. Materials which are either difficult to obtain, or are suspected to contain few mycobacteria only should be tested further by guinea pig inoculation.

Animals↗