Biomedical subjects

M Nováková

Publications and source records attributed to M Nováková.

At least 19 recordsLinked to original sources

PubMed2006

Developmental changes of some G-protein coupled receptors affected by c-fos knock-out.

The role of c-fos gene disruption on binding characteristics of selected G protein-coupled receptors has been investigated. The following receptors were studied: muscarinic receptors (MR), alpha1-adrenoceptors (AAR), beta-adrenoceptors (BAR), D1-like dopamine receptors (D1R), D2-like dopamine receptors (D2R). We have tested the hypothesis that c-fos gene disruption would not influence the receptor density in central nervous system (CNS: brain cortex and cerebellum) and in the periphery (lung, heart). We found that both in the periphery and in the CNS there were important changes in receptor density. Both MR and BAR were increased in the lung and heart. The effects of c-fos gene disruption in CNS were more selective. In general, the receptors that activate Gq-phospholipase C-proteinkinase C pathway (AAR, MR) were affected, while the others (that activate/or inhibit adenylyl cyclase: BAR, D1R, D2R) were not. These results show that disruption of c-fos gene could significantly change the expression of G protein-coupled receptors. Moreover, these changes could be comprehended as one of the adaptive mechanisms that help the organism to cope with c-fos gene disruption.

Animals↗

PubMed2005

Identification of all alpha1-adrenoceptor subtypes in rat lung.

The function of lung tissue is regulated via a release of neurotransmitters from autonomic nerves. The neurotransmitters of sympathetic nervous system, adrenaline and noradrenaline, activate both alpha-adrenoceptors and beta-adrenoceptors. Although the function and expression of beta-adrenoceptors can be considered major, some doubts exist about the function and expression of alpha1-adrenoceptor subtypes in the lung tissue. Therefore a set of competition binding experiments was employed in order to discriminate between the alpha1-adrenoceptor binding site subtypes in the rat lung. We identified three subpopulations of alpha1-adrenoceptor binding sites in the rat lung (alpha1A, alpha1B and alpha1D).

Animals↗

PubMed2000

Side reactions during photochemical cleavage of an alpha-methyl-6-nitroveratryl-based photolabile linker.

The mechanisms of reactions causing irreversible inhibition of the activity of enzymes when irradiated in the presence of the recently developed alpha-methyl-6-nitroveratryl-based photolinker [Holmes CP. J. Org. Chem. 1997; 62: 2370-2380] have been investigated. Several experiments based on the interaction of the photolinker with model peptides or n-butylamine have been accomplished. A complexity of products, resulting from the side reactions competing with the 'normal' photocleavage of the linker, have been found. The amino and thiol groups of the molecules present in the solvents upon irradiation were recognized as having a major influence on the course of photolysis. Some of these side products resulting from the interaction with amines were identified and the mechanisms by which they can be generated are discussed. The mechanism of the interaction of the thiol groups present in peptides or proteins with the photolinker is unclear and it remains to be further elucidated. It was found that the undesirable effects are favored by a basic pH and are largely reduced by a slightly acidic pH, together with the presence of dithiothreitol. Significant positive effects of dithiothreitol have been observed on the rate as well as the yield of the photocleavage. These results demonstrate that the use of photolabile linkers in biological media can be accompanied by undesired effects, which can be largely reduced by choosing appropriate conditions and additives.

Animals↗

PubMed1999

[Evaluation of the role of the HPV test in routine clinical practice: prospective study].

OBJECTIVE: To determine the incidence of papillomavirus and to asses the role a HPV DNA in screening of cervical intraepithelial neoplasia. DESIGN: Czech National Collaborative Trial. SETTING: Department of Gynaecology and Obstetrics, Kladno Hospital, Department of Microbiology, KLINLAB, Prague, outpatient clinics (Kladno, Bruntál, Unhost'). METHODS: The study group includes of 3,264 women, their cervical scrapings were sent to KLINLAB during November 1996 to June 1998, because of abnormal results of primary screening. Patients with ASCUS, AGNUS, LSIL, HSIL and/or abnormal colposcopic findings were eligible for this study. Only completely filled in records of a subgroup of 1,158 patients were assessed for sensitivity and specificity for CIN in screening methods. RESULTS: The overall sensitivity of cytology and basic colposcopy were 84.7% and 64.9% respectively. The overall sensitivity of HPV DNA testing was 66%. The sensitivity of cytology of women with minor cytological abnormities for major cervical disease (CIN 2/3 and microinvasive cancer) in this group of patients was only 35%. Combined cytology with HPV DNA test gave an increased sensitivity for major cervical disease of 83%. CONCLUSION: 153 (66.4%) of the cervical intraepithelial neoplasias grade 2/3 displayed negative and borderline or mild cytological changes. The combined use of cytology with HPV testing increased the sensitivity with a reduction of specificity. However, it is evident from these results that HPV DNA testing alone cannot be used as a diagnostic tool but could usefully improve the level of screening CIN in common clinical practice.

Adolescent↗

PubMed1997

Distinct subcellular localization of beta-tubulin epitopes in the adult mouse brain.

A panel of monoclonal antibodies specific of alpha-tubulin (TU-01, TU-09) and beta-tubulin (TU-06, TU-13) subunits was used to study the location of N-terminal structural domains of tubulin in adult mouse brain. The specificity of antibodies was confirmed b immunoblotting experiments. Immunohistochemical staining of vibratome sections from cerebral cortex, cerebellum, hippocampus, and corpus callosum showed that antibodies TU-01, TU-09, and TU-13 reacted with neuronal and glial cells and their processes, whereas the TU-06 antibody stained only the perikarya. Dendrites and axons were either unstained or their staining was very weak. As the TU-06 epitope is located on the N-terminal structural domain of beta-tubulin, the observed staining pattern cannot be interpreted as evidence of a distinct subcellular localization of beta-tubulin isotypes or known post-translational modifications. The limited distribution of the epitope could, rather, reflect differences between the conformations of tubulin molecules in microtubules of somata and neurites or, alternatively, a specific masking of the corresponding region on the N-terminal domain of beta-tubulin by interacting protein(s) in dendrites and axons.

Animals↗

PubMed1996

gamma-Tubulin redistribution in taxol-treated mitotic cells probed by monoclonal antibodies.

Monoclonal antibodies were prepared against conserved synthetic peptide from the C-terminus of the gamma-tubulin and their specificity was confirmed by immunoblotting, competitive enzyme-linked immunosorbent assay (ELISA) and immunofluorescence. The antibodies decorated interphase centrosomes as well as half-spindles and midbodies in mitotic cells of various origin. The prepared antibodies were used to study the gamma-tubulin distribution in nocodazole and taxol-treated cells. In the cells recovering from the nocodazole treatment, gamma-tubulin was found in centers of all microtubule asters. Examination of relative location of gamma-tubulin and microtubule asters in taxol-treated mitotic cells 3T3, HeLa and PtK2 revealed that the number of taxol-induced microtubule asters exceeded the number of gamma-tubulin-positive spots. The gamma-tubulin was often found in the periphery of microtubule asters. Centrosomal phosphoprotein epitope detected by MPM-2 antibody colocalized with gamma-tubulin in taxol-treated mitotic cells. The presented data suggest that taxol-induced microtubule asters are in vivo nucleated independently of gamma-tubulin, and other minus-end nucleator(s) are necessary for formation of such asters. Alternatively, gamma-tubulin is present in subthreshold amounts undetectable by immunofluorescence.

3T3 Cells↗

PubMed1995

Stability of monoclonal IgM antibodies freeze-dried in the presence of trehalose.

We describe the use of the disaccharide trehalose for stabilization of mouse monoclonal IgM antibodies during freeze-drying and prolonged storage at elevated temperatures. Spent culture media, ascitic fluids and isolated immunoglobulins were freeze-dried in the presence of trehalose, stored at different temperatures, and tested after rehydration for their binding to their corresponding antigens. Antibodies, directed against various types of antigens, effectively recovered their binding efficiency as tested in enzyme-linked immunoassays, flow cytometry and immunofluorescence. Application of trehalose for freeze-drying of labile monoclonal IgM antibodies permits convenient long-term storage of large quantities of antibodies, facilitates their transport at ambient temperature and simplifies the construction of pre-aliquoted kits based on such antibodies.

3T3 Cells↗

PubMed1995

Polyclonal activation of human lymphocytes by Bacillus firmus and its constituents.

Bacillus firmus strongly stimulates Ig synthesis in the cultures of human peripheral blood mononuclear leukocytes. As apparent from the character of Ig formation and blastic transformation, the stimulation has features of a polyclonal activation of B lymphocytes without substantial participation of T lymphocytes. B firmus is a strong B cell polyclonal activator even for human cord blood lymphocytes. The most striking feature is the strong stimulation of IgA synthesis in both adult and cord blood lymphocytes. Several crude fractions were isolated from B. firmus. None of them exhibited any remarkable enhancement of activity but the cytoplasmic fraction P-40 was clearly more potent than the intact bacilli. On the other hand, cell wall peptidoglycan, a well known polyclonal activator of B cells, had a much lower activity than whole bacteria. The effect of B. firmus on the stimulation of Ig formation is thus relatively complex; it is not caused mainly by peptidoglycan but rather by some cytoplasmic constituents of the bacterium.

Adult↗

PubMed1995

Vinorelbine and cisplatin in the treatment of advanced non-small cell lung cancer: results of a multicenter Czech study.

There is continuous discussion about the optimal treatment for patients with inoperable non small cell lung cancer. This is because chemotherapy can only improve the quality of life in a fraction of treated patients while prolonging survival by a couple of weeks at best. The new cytostatic drug "vinorelbine" has been tested in this indication during the last years. The drug has reached the response rate of 16 to 30% when used as monotherapy. The phase II studies proved the combination of vinorelbine with cisplatin to be the most efficient one and this combination was picked up for phase III clinical trials. The clinical trial with the aims to verify published data on treatment efficacy, to assess adverse effects of treatment and to evaluate appropriateness for routine application has been made in the Czech Republic. The treatment schedule was as follows: cisplatin (Platidiam Lachema) in a dose of 80 mg/m2 on day 1, vinorelbine (Navelbine Pierre Fabre) in a dose of 30 mg/m2 on days 1 and 8. The whole cycle was repeated on day 22. The treatment was applied for 12 weeks. After that the efficacy of treatment was evaluated and only the patients with regression or stabilization of the disease continued the treatment. 44 (35%) partial remissions and 3 (2.3%) complete remissions were achieved in a group of 126 evaluable patients. The effect of treatment was evaluated as stable disease in 35 (27%) patients while the progression of disease occurred in 38 (30%) patients. The tolerance of treatment using effective antiemetic support (ondansetron or granisetron) was fairly good.

Adult↗

PubMed1994

Effect of Bacillus firmus and other sporulating aerobic microorganisms on in vitro stimulation of human lymphocytes. A comparative study.

B. firmus activates human peripheral blood lymphocytes in vitro. Bacteria inactivated by heat or by formaldehyde were about equally effective, stimulating the blastic transformation of lymphocytes at doses of 10-200 mg/L and Ig formation in the culture at 10-500 mg/L. The action of formaldehyde treated B. firmus was compared with that of analogously inactivated B. subtilis, B. polymyxa, B. coagulans, B. megaterium, B. pumilus, B. cereus and B. lentus at a concentration of 100 mg/L. All these bacilli mildly stimulated blastic transformation and most of them substantially stimulated Ig formation, but B. firmus was the most efficient in stimulating the formation of Ig of all classes, in particular IgM and IgA. Its effect on Ig formation was comparable with that of PWM and was unusually high as compared with that of other bacteria. B. firmus is apparently a strong polyclonal activator of B lymphocytes. Its cells or their components could be potentially used for modulating immune reactions.

Bacillus↗

PubMed1994

Resistance to infection and activation of the monocyto-macrophage system caused by Bacillus firmus and its fractions.

Crude lipids isolated from Bacillus firmus, but not from other bacilli, were previously found to induce significant resistance against Listeria monocytogenes infection in mice. In this study, formaldehyde- and heat-killed bacterins of eight Bacillus species and some cellular fractions of B. firmus were prepared and tested for further immunomodulatory activities. Crude lipids, their aqueous extract, LTA, Protodyne and Pex-residue preparations exhibited a strong anti-infection activity, whereas Pextract, P40 and all bacterins tested had no effect. Formaldehyde-killed bacterins, live bacteria and the P40 preparation of both B. firmus strains, as well as bacterins of both B. subtilis strains, induced pronounced splenomegaly in mice. Peptidoglycan and Pex-residue induced significant depression of cytochrome P-450 in mouse liver microsomes after application of 0.1 mg per mouse. Optimal conditions for obtaining a bacterial suspension exhibiting these immunomodulatory properties were elaborated.

Adjuvants, Immunologic↗

PubMed1991

Naming and identification of tastes in aqueous solutions.

Several taste substances were tested in aqueous solutions; tannic and tartaric acids were found unsuitable as a standard substance for the taste identification. Monosodium glutamate, sodium hydrogen carbonate and potassium chloride were often identified as salty substances even when the subjects were able to distinguish between the tastes. They probably identified the taste as salty owing to the lack of proper terms, and unsufficient experience with tasting monosodium glutamate and sodium hydrogen carbonate as substances possessing defined tastes different from the salty taste.

Czechoslovakia↗

PubMed1987

Platinum cytostatics influence--the primary antibody response of mouse spleen cells in vitro.

The effects of three platinum containing cytostatic drugs--cis-DDP, CBDCA, and OXO--on in vitro primary antibody production after the treatment of mouse spleen cells with these compounds were studied. The technique of Marbrook was employed, the antibody response was assessed according to the number of plaque-forming cells (PFC) after the antigenic stimulation by sheep red blood cells (SRBC) in vitro. All of the three platinum complexes studied had inhibitory effect on antibody response at concentrations of 1 X 10(-5) to 1 X 10(-7) mol/l without affecting the viability of the mouse spleen cells. A comparison of the effectiveness of the three cytostatic drugs showed that cis-DDP was the most potent inhibitor. To obtain a similar inhibitory effect with CBDCA and OXO, concentrations 10 times as high as that in cis-DDP were required, depending on the time relation to antigenic stimulation. The lowest inhibitory effect on antibody production was observed in CBDCA. These drugs acted either after a simultaneous administration or 48 h after the antigen, i.e., at the time of maximal proliferation and differentiation of the cells. DNA synthesis must undoubtedly have been affected as well.

Animals↗

PubMed1986

Preparation and characterization of hybridomas producing monoclonal antibodies against human alpha interferon.

Hybridomas producing monoclonal antibodies against human alpha interferon (hu-IFN alpha) were constructed by fusion of NSO myeloma cells with spleen cells of BALB/c mice immunized with purified hu-IFN alpha. Altogether, 527 hybridomas were prepared in two separate experiments. From this cohort of hybridomas, 51 produced monoclonal antibodies against hu-IFN alpha. Seventeen out of fifty one hybridomas produced antibodies with neutralizing capacity for IFN while 34 hybridomas produced monoclonal antibodies with binding ability not accompanied with the neutralization of biological activity of IFN. The specificity of antibodies was determined with 3 types of tests: ELISA, ELISAN (modified ELISA) and neutralization test. Using isotype analysis, it has been found that 23 monoclonal antibodies were of IgM class, 20 were of IgG1 subclass, 4 were of IgG2b and 4 of IgG3 subclass. The average number of chromosomes in hybridomas was between 61.35 and 78.55. Their average doubling time was between 13.95 and 25.76 hrs.

Animals↗

PubMed1986