Biomedical subjects

P Filipcík

Publications and source records attributed to P Filipcík.

11 recordsLinked to original sources

PubMed2003

First confirmed sheep scrapie with A136R154Q171 genotype in Slovakia.

The first confirmed evidence of scrapie in Slovakia was demonstrated in one sheep of the autochthonous Merino breed from the southeastern part of the country. The reported scrapie was diagnosed during compulsory transmissible spongiform encephalitis (TSE) screening of sheep over 9 months of age assigned for consumption. The positive ewe was 5-year-old, which did not show any clinical signs of scrapie. The presence of the proteinase-resistant prion protein (PrP) in brain was proved independently by two laboratories using two different immunochemical screening systems, namely the Prionics Check (Western blot analysis) and Enfer TSE enzyme-linked immunosorbent assay (ELISA). In addition, the genotyping analysis of PrP gene demonstrated the presence of PrP genotype from the high risk group R4. The affected sheep was homozygous for the allele PrP(ARQ) (ARQ/ARQ) coding for alanine (A), arginine (R) and glutamine (Q) at three most relevant codons (136, 154 and 171, respectively). The healthy sister of the positive ewe was heterozygous in the PrP locus and carried alleles ARQ/ARR.

Amino Acid Sequence↗

PubMed1998

Thyroid hormone receptor occupancy and biological effects of 3,5,3,-L-triiodothyronine (T3) in GH4C1 rat pituitary tumour cells.

The GH4C1 pituitary cell line, an excellent model for a thyroid hormone action study, was used for determination of the relationship between thyroid hormone receptor occupancy and intensity of cell proliferation, prolactin (PRL) production, thyrotropin (TSH) inhibition and 3,5,3,-L-triiodothyronine (T3) receptor down-regulation. Nuclear receptor population was progressively occupied by T3 in concentrations ranging from 0.025 to 10.0 nM T3. Bmax ranged from 0.029 fmol/10(6) cells at the lowest T3 concentration to Bmax = 12.51 fmol/10(6) cells at the highest concentration. Each of the observed biological events is operative within distinct dose-response ranges in cultured GH4C1 cells. The maximal biological response (except the TSH inhibition and T3 receptor down-regulation) does not require the occupation of the whole nuclear receptor population by T3 and the intensity of none of the responses studied was directly proportional to thyroid hormone receptor occupancy.

Animals↗

PubMed1996

[The basis for the variable effects of thyroid hormones].

Among physiological reactions of the organism, the multiplicity of action of thyroid hormones is a well known phenomenon. Thyroid hormones (TH) regulate activity of other hormones, receptors for bioactive signals, enzymes, and the function of ion channels. Until triiodothyronine has been identified as a ligand for oncoprotein c-erbA, this broad potency of actions has been mysterious. C-erbA has been recognized to be a transcription factor and an authentic thyroid hormone receptor. Important evidence comes from molecular studies, which have described isoforms of c-erbA and other members of intranuclear receptor family, their heterodimerization, thyroid hormone responsive elements in the target genes, and the existence of the cross-talk mechanism. Till present, much has been learned about TH transcription regulations in vitro. An open question remains whether this regulations are operative also in the intact organism.

Animals↗

PubMed1995

In vitro effects of sodium selenite on nuclear 3,5,3'-triiodothyronine (T3) receptor gene expression in rat pituitary GH4C1 cells.

The present study was undertaken in order to investigate the effects of sodium selenite on: 1. The growth of rat pituitary GH4C1 cells; 2. The nuclear T3 receptor gene expression; 3. The cytoplasmic protein phosphorylation; and 4. The prolactin secretion in rat pituitary GH4C1 cell line. Sodium selenite (up to 2.5 microM) has no inhibitory effect on GH4C1 cell proliferation as well as the prolactin secretion. On the other hand, 0.5 microM sodium selenite significantly decreases the rate of mRNA synthesis and/or degradation of both, the alpha 1 form of the T3 receptor (TR alpha 1) and the alpha 2 isoform of the T3 receptor. At 1 microM of sodium selenite, significant changes in the electrophoretic profile of low molecular mass cytoplasmic proteins were found, moreover, sodium selenite (1 microM) also considerably affects phosphorylation of a higher molecular mass proteins. The results based on the in vitro experiments suggest that sodium selenite may affect specific processes at the pretranslational level as well as it may also take part in processes of posttranslational modification of protein(s), the cell vitality and the cell growth remaining unchanged.

Animals↗

PubMed1992

Thyroid hormone responsiveness of the L1210 murine leukemia cell line.

The presence of saturable and high affinity 3,5,3'-triiodothyronine (T3) binding sites was demonstrated in L1210 murine leukemia cell nuclei. Scatchard analysis revealed one class of receptors for T3 with Ka = 2.187 x 10(9) l/mol and a maximum binding capacity (Bmax) of 3.96 fmol/10(6) cells. The effects of T3 on protein phosphorylation and growth rate of L1210 cells were investigated in a medium containing T3-depleted fetal calf serum. T3 was observed to be effective in enhancing protein phosphorylation (153.06% +/- 5.99 SD) compared to cells grown in the absence of T3 (81.49% +/- 13.50 SD). Moreover, in the presence of high T3 concentration (11.15 nmol/l) T3 was found to significantly increase the cell growth rate. In addition, the T3 receptor-associated alterations during the cell cycle, as measured by flow cytometry, suggest that the presence of T3 receptors becomes evident during the late G1 phase of the cell cycle, and T3 receptor numbers increase during the S phase. These results suggest that in in vitro conditions representing high T3 concentration, the number of L1210 leukemia cells may be increased by T3 via nuclear receptors. The L1210 leukemia cell line may serve as a convenient tool for in vitro studies of nuclear receptors and/or mechanism of action of T3. The binding affinity of T3 receptors is similar to that found in rat hepatocytes or human lymphocytes.

Animals↗

PubMed1992

Distribution of triiodothyronine nuclear receptors during the cell cycle in mouse leukemia cells.

The process of the appearance of thyroid hormone receptors in the cell cycle was studied in mouse leukemia cells L1210. After cell synchronization by 2 mM thymidine for 12 h followed by 80 nM Colcemid for 4 h, the specific binding of triiodothyronine (T3) to its nuclear receptors was determined 3, 6, 9 and 12 h after release from the thymidine-Colcemid block. Three h after release from the block, [125I]T3 specific binding was 11.4 +/- 2.5% of a control value measured for an asynchronous population. An upward slope in progression of T3 nuclear receptors was found 6 h (32.3% +/- 4.5%), 9 h (47.8% +/- 5.2%) and 12 h (83% +/- 4.3%) after release from thymidine-Colcemid block. The data suggest that processes involving T3 receptor promotion in cell nuclei are operative within the late G1 and S phases of the cell cycle, and thus the increase in T3 receptor concentration in the nuclei is in a positive correlation with the number of cells in the S compartment of the cell cycle.

Animals↗

PubMed1992

Effect of protease inhibitors and substrates on 3,5,3'-triiodothyronine binding to rat liver nuclear receptors.

The effect of protease inhibitors N-tosyl-L-phenylalanine chloromethyl ketone (TPCK) and N-carbobenzoxy-L-phenylalanine chloromethyl ketone (ZPCK) at concentrations ranging from 1.5 x 10(-6) mol/l to 1.5 x 10(-4) mol/l on the specific binding of 3,5,3'-triiodothyronine (T3) to rat liver nuclear receptors was evaluated. Both TPCK at 1.5 x 10(-5) mol/l (P < 0.001) and ZPCK at 1.5 x 10(-6) mol/l (P < 0.05) showed the inhibition of T3 binding to nuclear receptors. The evaluation of T3 binding data following separation of unbound TPCK from treated nuclear receptors on a Sephadex G-25 column showed that the inhibition of T3 binding was irreversible, since a substantial decrease of the equilibrium association constant (Ka) was found when compared to the mock samples lacking TPCK. In addition, similar inhibitory effect on T3 specific binding to rat liver nuclear receptors was found at 5.0 x 10(-4) mol/l by protease substrates L-tyrosine benzyl ester (P < 0.001), L-tyrosine ethyl ester (P < 0.02), L-tryptophan methyl ester (P < 0.02) and L-tryptophan ethyl ester (P < 0.05). The data suggest that: 1. both protease inhibitors and substrates tested inhibited T3 specific binding to T3 nuclear receptors; 2. this may support the hypothesis that T3 receptors like other receptors encoded by c-erbA gene possess a site that recognize both serine protease inhibitors and substrates in its hormone binding domain.

Amino Acid Chloromethyl Ketones↗

PubMed1992

Effect of triiodothyronine on rat liver polysome profiles and translational activity of mRNA after partial hepatectomy.

The administration of 3,5,3'-L-triiodothyronine (T3) (200 micrograms/100 g) to rats immediately after partial hepatectomy led to an increase in total polysome content of residual hepatocytes (as measured 18 h postoperatively) which exceeded that observed after partial hepatectomy in the absence of hormone. The percentage of free ribosome pool remained the same after partial hepatectomy irrespectively on the absence or presence of T3. After partial hepatectomy the sedimentation pattern of total polysomal fraction (isolated 18 h postoperatively) shifted towards smaller aggregates as compared with that isolated from sham operated animals. T3 did not affect this pattern. The translational capacity of mRNA isolated from regenerating liver after 18 h was higher than that of mRNA isolated from sham operated animals. T3 increased the translational capacity of mRNA isolated from regenerating liver if administered immediately after surgery. Two dimensional electrophoresis of translated products showed that one of the typical proteins recently characterized with Mr 25,000 pI 6.9 appeared after partial hepatectomy and was significantly increased when T3 was administered immediately after surgery. These results show that thyroid hormone can enhance some of the characteristics features of liver regeneration involved in the synthesis of proteins typical for the process of liver regeneration.

Animals↗

PubMed1990

[Cell lines in experimental endocrinology].

Cell lines derived of endocrine tissues which are most frequently employed in experimental endocrinology are described. The cell lines represent a useful experimental model for the study of the control of synthesis and release of hormones and hormone-like agents as well as for the study of mechanisms of action of these agents in target tissues at the cellular and subcellular level. A number of the cell lines know so far are able to grow in serumfree media. These media are completely defined. This approach is promising for further progress in cellular endocrinology.

Animals↗

PubMedDate not supplied

Nuclear all-trans retinoic acid receptors: in vitro effects of selenium.

The present study was undertaken to investigate the effects of selenite (SeIV) and selenate (SeVI) on the all-trans retinoic acid (RA)-nuclear retinoic acid receptor (RAR) complex formation in rat liver. We also present the data on the in vitro effects of SeIV on the RARalpha and the type I iodothyronine 5'-deiodinase gene expression in the GH4C1 rat pituitary tumor cells. SeIV at 1.0 micromol/L was found to reduce (p < 0.05) the RA specific binding to RAR in rat liver. Dithiothreitol (DTT), a protective agent for sulfhydryl groups, was found to be slightly effective in protecting the RAR binding properties when affected by SeIV. SeVI at 0.1 micromol/L reduced (p < 0.05) the RA specific binding to RAR in liver, as well. Seleno-L-methionine (Se-II) when compared to L-methionine did not exert any inhibitory effect on the formation of the RA-RAR complex. SeIV (up to 2.5 micromol/L) has no inhibitory effect on GH4C1 cell proliferation as well as the prolactin secretion. SeIV at 1.0 micromol/L significantly decreases the rate of mRNA synthesis and/or degradation of the alpha form of the RAR and causes the enhancement of the type I iodothyronine 5'-deiodinase gene expression in GH4C1 cells. The results based on in vitro experiments suggest that inorganic selenium may affect the RA specific binding to their cognate receptor molecules, and it may reduce expression of the gene encoding the RARalpha, with the cell vitality and the cell growth remaining unchanged.

Animals↗

PubMedDate not supplied

Effect of selenite and selenate on rat liver nuclear 3,5,3'-triiodothyronine (T3) receptor.

The present study was undertaken to investigate the effects of selenite (SeIV) or selenate (SeVI) on nuclear T3 receptors of rat liver. Selenite at 0.1 microM (p < 0.01) inhibited the T3 specific binding to rat liver nuclear receptors. The specific binding of the T3 receptor was fully restored when even 1.0 microM selenite was separated from the T3 receptor by gel filtration. No inhibitory effect of selenite (up to 100 microM) on the T3 binding to nuclear receptor was found in the presence of 1.0 mM dithiothreitol. The rate of dissociation of the T3-nuclear receptor complex was effectively increased by 0.1 microM selenite. Selenate up to 1 mM as well as sulfite or sulfate up to 0.1 mM did not exert an inhibitory effect on T3 receptors. The results based on the in vitro experiments suggest that the selenium in the form of selenite may reversibly affect the T3 binding on the receptor molecule.

Animals↗