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D Kanazir

Publications and source records attributed to D Kanazir.

At least 19 recordsLinked to original sources
PubMed2001

Ontogenetic profile of ecto-ATPase activity in rat hippocampal and caudate nucleus synaptic plasma membrane fractions.

An ontogenetic study of ecto-ATPase activity and the content of enzyme proteins was assessed in the caudate nucleus and hippocampal synaptic plasma membranes isolated from rats at various ages (15, 30, 90, 180 and 365 days). The ontogenetic profile revealed that the enzyme activities in both brain areas were the highest on day 30 and 365, while the ecto-ATPase protein abundance was the highest on day 15 after birth. Possible explanation for obtained ontogenetic profile and the discrepancy between activity and abundance may reside in the fact that ecto-ATPase during development could exert additional roles other than those related to metabolism of ATP. It is likely that ecto-ATPase, regulating the concentration of ATP and adenosine in synaptic cleft, has important role in the processes of brain development and aging.

Adenosine↗
PubMed1999

Glucocorticoid receptors in ageing rats.

The role of the glucocorticoid receptor (GR) in senescence was studied in rats of increasing age. Statistically significant changes in the number of GRs from rat liver were detected, whereas the affinity for the ligand triamcinolone acetonide (TA) did not change with increasing age, and was in the range of 1-2 nM. In all cases the number of receptors was lower in rats treated with hormone in vivo relative to untreated animals. In addition, we have found changes in GR activation, as measured by the binding to DNA cellulose in the mentioned age groups. Furthermore, expression of the glucocorticoid hormone (GH)-inducible gene, tyrosine amino transferase (TAT) also showed age-related alterations. We conclude that receptor function shows oscillatory changes during ageing. In addition, response to GH generally declines towards the older age. This specific periodicity in functional characteristics of the GR may reconcile conflicting results about the receptor number and properties during the ageing process, and marks particular age at which individual organism shows the highest or the lowest sensitivity to the actions of GH.

Aging↗
PubMed1999

Identification and characterization of glucocorticoid receptors in B16 mouse melanoma cells.

OBJECTIVE: To gain better insight into the role of glucocorticoids as modulators of cell growth, as well as to investigate the presence and characteristics of glucocorticoid receptors (GR) in mouse melanoma cells. METHODS: In two different B16 mouse melanoma cell clones (B16/F10 and B16/C3) the role of synthetic glucocorticoids (triamcinolone acetonide, TA) as cell growth modulators was investigated. RESULTS: The inhibitory effect of TA on B16/F10 cell growth after 8 days in culture was observed. The same hormonal treatment applied on B16/C3 melanoma cells also provoked changes in the cell growth. Dot blot analysis, using monoclonal antirodent glucocorticoid receptor antibodies showed the presence of receptor protein in both cell clones. The analysis of glucocorticoid receptors in B16/F10 and B16/C3 cell cytosol by Scatchard assay and ion-exchange chromatography on DEAE-Sephadex A-50 minicolumn indicated that the changes in melanoma cell growth may be mediated by glucocorticoid receptors and may relieve changes in the GR itself. CONCLUSIONS: It was found that B16/C3 melanoma cells exhibited different growth pattern under TA treatment when compared to the results obtained with B16/F10 cells. Such differences may be mediated by glucocorticoid receptors.

Animals↗
PubMed1998

Using yeast to study glucocorticoid receptor phosphorylation.

The glucocorticoid receptor (GR) is a phosphoprotein and a member of the steroid/thyroid receptor superfamily of ligand dependent transcription factors. When the glucocorticoid receptor is expressed in yeast (Saccharomyces cerevisiae), it is competent for signal transduction and transcriptional regulation. We have studied the glucocorticoid receptor phosphorylation in yeast and demonstrated that the receptor is phosphorylated in both the absence and presence of hormone, on serine and threonine residues. This phosphorylation occurs within 15 min upon addition of radioactivity in both hormone treated and untreated cells. As reported for mammalian cells, additional phosphorylation occurs upon hormone binding and this phosphorylation is dependent on the type of the ligand. We have followed the hormone dependent receptor phosphorylation by electrophoretic mobility shift assay, and have shown that this mobility change is sensitive to phosphatase treatment. In addition, the appearance of hormone dependent phosphoisoforms of the receptor depends on the potency of the agonist used. Using this method we show that the residues contributing to the hormone dependent mobility shift are localized in one of the transcriptional activation domains, between amino acids 130-247. We altered the phosphorylation sites within this domain that correspond to the amino acids phosphorylated in mouse hormone treated cells. Using phosphopeptide maps we show that hormone changes the peptide pattern of metabolically labelled receptor, and we identify peptides which are phosphorylated in hormone dependent manner. Then we determine that phosphorylation of residues S224 and S232 is increased in the presence of hormone, whereas phosphorylation of residues T171 and S246 is constitutive. Finally, we show that in both yeast and mammalian cells the same residues on the glucocorticoid receptor are phosphorylated. Our results suggest that yeast cells would be a suitable system to study glucocorticoid receptor phosphorylation. The genetic manipulability of yeast cells, together with conservation of the phosphorylation of GR in yeast and mammalian cells and identification of hormone dependent phosphorylation, would facilitate the isolation of molecules involved in the glucocorticoid receptor phosphorylation pathway and further our understanding of this process.

Animals↗
PubMed1998

Influence of pyridine and urea on the rat brain ATPase activity.

The neurotoxicity of pyridine and urea was investigated in respect to their ability to alter the activity of synaptosomal membrane Na+/K(+)-ATPase and Mg(2+)-ATPase. In vitro treatment with pyridine and urea stimulated Na+/K(+)-ATPase activity in a dose-dependent manner up to 40% and 60%, respectively. Mg(2+)-ATPase activity increased up to 40% after pyridine treatment, while urea had no effect at all. The neuroactive potencies of pyridine and urea were evaluated by estimating parameters Km and delta Vmax for enzyme stimulation, as well as Hill coefficient to estimate the levels of cooperativity for pyridine and urea binding. The results suggest that pyridine stimulates both enzymes, probably by interacting with some neuronal membrane components, and altering the lipid micro-environment of the ATPases. In contrast, urea stimulates the Na+/K(+)-ATPase only, assumingly by acting on it directly or via some other regulatory mechanism. Stimulation of Na+/K(+)-ATPase and Mg(2+)-ATPase by the substances tested and subsequent alteration of neuronal cell functioning could contribute to the CNS dysfunction upon chronic exposure to pyridine and urea.

Animals↗
PubMed1997

Estradiol in vitro modulates Na+-dependent Ca2+ uptake by synaptic plasma membrane vesicles of rat brain regions.

Membrane vesicles loaded with [Na+], prepared from synaptosomal plasma membranes (SPM) of whole brains (WB), hippocampi (Hip) and caudate nuclei (NC) of female rats, were used to study Na+ -dependent Ca2+ transport across SPM vesicles under the influence of 17beta-estradiol (E2) in vitro. In concentrations near to physiologic, E2 significantly increased 45Ca2+ uptake by SPM vesicles from all the brain tissues investigated. The maximum increase was observed for WB (21%) and Hip (33%) at 10(-9) mol/l, and for NC (31%) at 5 x 10(-9) mol/l of E2. These results (a) confirm our earlier finding that E2 in vitro modulates Na+-dependent Ca2+ transport across synaptosomal membrane in rat brain regions, and (b) suggest Na+/Ca2+ exchange as principal mechanism of the E2-stimulated Na-dependent Ca2+ uptake by membrane vesicles. The involvement of any ATPases as possible mediators is discussed.

Adenosine Triphosphatases↗
PubMed1988

Autocrine differentiation-inhibiting factor (ADIF) from chicken erythroleukemia cells acts on human and mouse early BFU-E erythroid progenitors.

tsAEV-LSCC HD3 chicken erythroid cells transformed by the avian erythroblastosis virus (AEV) secrete an autocrine differentiation-inhibiting factor, ADIF, which blocks differentiation without affecting proliferation of the chicken erythroid cells that synthesize and secrete it into the culture medium. The chicken erythroleukemia cell ADIF activity is not restricted to avians. It prevents dimethylsulfoxide (DMSO) from stimulating murine Friend erythroleukemia cells to synthesize hemoglobin. ADIF also blocks erythroid differentiation in normal human and murine bone marrow where it selectively targets the early BFU-E (burst-forming) erythroid precursor cells without affecting the more advanced CFU-E erythroid precursor cells or cells of the different granulocyte-macrophage lineage.

Animals↗
PubMed1987

AEV-transformed chicken erythroid cells secrete autocrine factors which promote soft agar growth and block erythroleukemia cell differentiation.

LSCC HD3 chicken erythroleukemia cells, transformed by a temperature-sensitive avian erythroblastosis virus (tsAEV), secreted into the medium several transforming factors which after separation by Bio-Cel P-60 chromatography, stimulated quiescent (G0) chicken embryo fibroblasts and NIH 3T3 mouse cells to replicate DNA in serum-free medium and to form colonies in soft agar. Most of these factors were also mitogenic for the LSCC HD3 cells themselves when they were rendered phenotypically untransformed by incubation at 42 degrees C to inactivate the ts AEV. The transformed LSCC HD3 cells also secreted a non-mitogenic 40 kDa factor which blocked the erythropoietin-induced differentiation of untransformed LSCC HD3 (at 42 degrees C) and the DMSO-induced differentiation of Friend murine erythroleukemia cells into hemoglobin-synthetizing erythroid cells.

Alpharetrovirus↗
PubMed1987

Reported herpes-virus-infection, fever and cancer incidence in a prospective study.

As soon as the first clinico-epidemiology reports appeared describing an association of herpes virus infection with genital cancer, relevant questions were introduced into an ongoing follow-up of a cohort already being studied for psychosocial risk factors in cancer. The study, which was initiated in 1966, comprised 1353 persons; disease incidence was determined in 1976. Incidences of cancer (including extragenital cancer) were found to be directly related to the reported prevalence of genital herpes symptoms, but were related inversely to extragenital herpes prevalence and to previous fever episodes. With regard to the relatively common incidence of "fever blisters", i.e. facial herpes, attributed to HSV-type 1, the latter findings is less surprising than the strong association of HSV type 2 lesions with overall cancer incidence. This association was particularly noticeable in individuals who had not reported episodes of fever earlier. These findings indicate the predictive role of certain host factors which are possibly related to systematic responses of the organism, including a diminished protection against (latent) herpes genitalis infection (recurrences). Further prospective studies are needed to investigate the proper time-relationship between clinically-overt herpes genitalis and the manifestation of cancer and its possible role in provoking the recurrent eruption of latent infections.

Adult↗
PubMed1986

[Mitogenic action of factors secreted by avian erythroblastosis virus transformed cells].

We describe here the capacity of erythroid LSCC HD3 cells, transformed with a ts mutant of avian erythroblastosis virus, to grow in a chemically defined medium without serum at 36 degrees C, but not at 41 degrees C. At this latter temperature the activity of v-erbB oncogene is suppressed. However, cell growth at 41 degrees C could take place either by addition of the medium derived from LSCC HD3 cells grown at 36 degrees C (conditioned medium), or by addition of fetal calf serum. These results show that LSCC HD3 cells, maintained under conditions in which the v-erbB oncogene is active, secrete growth factor(s) which exhibit a mitogenic effect similar to that observed with calf serum.

Alpharetrovirus↗
PubMed1986

Sex steroid receptors in transformed human cervical tissue.

Investigation of the binding affinity, the concentration and the DNA binding ability of the sex steroid receptors in transformed human cervical tissue has shown considerable changes in comparison to normal specimens. Lower level of hormone receptors and higher dissociation constants are the essential characteristics of the majority of analysed transformed tissue specimens. The DNA binding of steroid-receptor complexes is in agreement with mentionated data. These preliminary results are just one more evidence on the existence of relationship between modified properties of sex steroid receptors and different histological alterations of their target tissues. Further investigations are necessary to make some conclusion about the possible involvement of estrogen and progesterone receptors in pathological transformation of the portio vaginalis uteri.

Adenocarcinoma↗
PubMed1985

Steroid receptors in human uterine carcinoma. Their biological importance and therapeutic implications.

Surgical material of primary uterine carcinoma from postmenopausal patients was analyzed with regard to cytosol content of estradiol (ER) and progesterone (PR) receptors, as well as their binding sites in nuclear compartment. A dextrancoated charcoal technique was used and binding data were calculated from Scatchard plots. In all examined specimens intracellular high-affinity, low-capacity estrogen - and progesterone-binding proteins (which have the characteristics of steroid receptors), with equilibrium dissociation constants (Kd's) of 10(-10)M and 10(-9)M respectively, have been observed in detectable levels. DNA binding ability of steroid-receptor complexes was examined and clearly demonstrated even at 4 degrees C by using DNA-cellulose slurry. Preheating of complexes at 25 degrees cause increased DNA binding ability in some specimens, but significant loss of this ability in other tumors. The relationship between the nuclear retention of steroid-receptor complexes and their interaction with nuclear components (giving a response) is discussed on the basis of steroid-responsive and unresponsive systems. Present investigation indicate that described steroid analysis may become an important tool in predicting the value of endocrine therapy in human uterine carcinoma.

Cell Nucleus↗
PubMed1979

Cortisol-binding components of cytosol receptor in normal and adrenalectomized rat liver.

[3H] cortisol was found to be bound to two distinct components of receptor protein in hepatic cytosol of both normal and adrenalectomized adult male rats. In liver cytosol of normal rats, 78% of total bound [3H] cortisol to receptor was associated with the first receptor component, and about 20% to the second one. However, the first component of cytosol receptor in adrenalectomized rats was found to bind 95% of total [3H] cortisol bound to both receptor components, while only 4.5% of the bound hormone was found associated with the second receptor component. These alterations in binding capacity are discussed in relation to possible regulation of nuclear RNA synthesis by cortisol-receptor complexes.

Adrenalectomy↗