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A Bogdanova

Publications and source records attributed to A Bogdanova.

At least 19 recordsLinked to original sources
PubMed2005

Na-K-ATPase in rat cerebellar granule cells is redox sensitive.

Redox-induced regulation of the Na-K-ATPase was studied in dispersed rat cerebellar granule cells. Intracellular thiol redox state was modulated using glutathione (GSH)-conjugating agents and membrane-permeable ethyl ester of GSH (et-GSH) and Na-K-ATPase transport and hydrolytic activity monitored as a function of intracellular reduced thiol concentration. Depletion of cytosolic and mitochondrial GSH pools caused an increase in free radical production in mitochondria and rapid ATP deprivation with a subsequent decrease in transport but not hydrolytic activity of the Na-K-ATPase. Selective conjugation of cytosolic GSH did not affect free radical production and Na-K-ATPase function. Unexpectedly, overloading of cerebellar granule cells with GSH triggered global free radical burst originating most probably from GSH autooxidation. The latter was not followed by ATP depletion but resulted in suppression of active K(+) influx and a modest increase in mortality. Suppression of transport activity of the Na-K-ATPase was observed in granule cells exposed to both permeable et-GSH and impermeable GSH, with inhibitory effects of external and cytosolic GSH being additive. The obtained data indicate that redox state is a potent regulator of the Na-K-ATPase function. Shifts from an "optimal redox potential range" to higher or lower levels cause suppression of the Na-K pump activity.

Adenosine Triphosphate↗
PubMed2005

Neuroprotection by hypoxic preconditioning: HIF-1 and erythropoietin protect from retinal degeneration.

Hypoxic exposure of cells or organisms induces expression of a number of hypoxia responsive genes through the activation of the hypoxia-inducible factor-1 (HIF-1). One of the most prominent HIF-1 targets is erythropoietin that has beneficial effects on ischemia-related injury in the brain. Exposure to low environmental oxygen concentrations can be used as a preconditioning paradigm to protect cells or tissues against a variety of harmful conditions. Here, we summarize recent work on neuroprotection of retinal photoreceptors and ganglion cells induced by hypoxic preconditioning or by systemically elevated levels of Epo in mouse plasma.

Animals↗
PubMed2005

Hypoxic responses of Na+/K+ ATPase in trout hepatocytes.

Reduction in oxygenation induces inhibition of Na+/K+ ATPase in a number of cells and tissues, including hepatocytes. When not reversed, decrease in Na+/K+ pump activity leads to a gradual Na+ accumulation, cell swelling and death. However, when accompanied by suppression of dissipative cation pathways, it has also been shown to be a beneficial adaptive strategy used by some hypoxia-tolerant species to reduce ATP consumption during prolonged periods of anoxia. This study aims to investigate acute hypoxic responses of the Na+/K+ ATPase in primary cultures of trout hepatocytes. Gradual decrease in oxygenation was followed by an instantaneous transient dose-dependent downregulation of the Na+/K+ ATPase transport activity, but was without an effect on hydrolytic function of the enzyme. Hypoxia-induced inhibition of active K+ influx was reversed spontaneously when hypoxic incubation time exceeded 20 min. The stimulating effect of prolonged hypoxic exposure on the Na+/K+ pump is most probably secondary to hypoxia-induced activation of the Na+/H+ exchanger with the following Na+ accumulation leading to Na+/K+ ATPase activation. Hypoxia-induced inhibition of the Na+/K+ pump was not caused by ATP depletion or global oxidative stress. However, local controlled production of reactive oxygen species seems to play an important role in hypoxia-induced regulation of the Na+/K+ ATPase. Treatment of cells with mercaptopropionyl glycine (MPG), a scavenger of OH*-, abolished hypoxia-induced inhibition of the Na+/K+ ATPase. Earlier on we have shown that activation of Na+/H+ exchanger under hypoxic conditions can be opposed by MPG treatment as well. Taken together our results suggest that regulation of both oxygen-sensitive transporters may be accomplished by local changes in free radical production.

Adenosine Triphosphate↗
PubMed2004

[Use of recombinant factor VIIa for the control of massive bleeding caused by uterine hypotonia in post-placental period].

We report our clinical opinion for recombinant activated factor VII (NovoSeven, Novo Nordisk, Copenhagen, Denmark) administration in puerperae with massive haemorrhage caused by uterine hypotonia. Four women with severe bleeding in post-placental period received NovoSeven in bolus IV. The blood loss and laboratory changes in hematology and haemostasis parameters are monitored. The right time of application and the mean effective dose of the medication are discussed. The bleeding was ceased in all cases. Decrease in values of Hb, Er and PTT was noted. The mean administered dose of 72 micrograms/kg BW was effective. The laboratory values showed tendency for improvement on the 24 hour after administration and normal levels on discharge. The use of recombinant factor VIIA in puerperae with severe bleeding in the postplacental period is effective and safe enough and could be an alternative to the extreme surgical procedures.

Adult↗
PubMed2004

[Ferro-Folgamma--a drug for treatment and prophylaxis of iron deficiency anemia in pregnant women].

The problem of iron deficiency anaemia (IDA) in pregnant women is not a new one, but the flashback to it is justified because of the fact that its significance is not appreciated properly. The growing foetus has increased needs of different active for blood formation substances such as iron (Fe), folic acid, vit. B12, which are taken away from the mother. If her supplies are not enough, an anaemic syndrome can be promoted. The only suitable way in the presence of iron deficiency is the administration of drugs for equilibration of iron balance. We used Ferro-Folgamma--a new medicine for our pharmaceutical market, for treatment of IDA in 42 pregnant women and we rendered an account of the results of its administration. All pregnant women had starting data of Hb<110 g/l and Hct<0.33 L/L. One capsule of Ferro-Folgamma contains 100 mg iron sulfate siccatum (that corresponds to 37 mg Fe), folic acid - 5 mg, cyancobalamine 10 mg. It is administered a capsule 3 times daily in 1 to 3 courses of treatment and a course has 20 days duration. After a treatment course was carried out the starting data of Hb were increased with 8.73 g/l, and of Hct with 0.02. In 8 pregnant women after the first therapeutic course, a 20-days - treatment was conducted too and Hb rose with 18.14 g/l in comparison with the starting data, and of Hct - with 0.037. The authors recommend the utilization of Ferro-Folgamma for treatment and prophylaxis of IDA in pregnant women, because of its good gastric acceptance, a few side undesired reactions, and the supplement of Folic acid and vit B12 increases the iron resorbtion.

Anemia, Iron-Deficiency↗
PubMed2004

[Clinical aspects of the issue "pregnancy complicated by syphilis"].

UNLABELLED: Syphilis is a disease with many social, cultural and ethico-moral implications. During the course of pregnancy it may lead to serious fetal disorders and eventually to its intrauterine death. With timely diagnosis, contemporary treatment is uttermost effective. AIM: Analysis of the frequency of syphilis among pregnant women, undergone treatment in the Quarantine Isolation Sector (QIS) with the Clinic "High risk pregnancy", at the University Multifunctional Hospital for Active Treatment (UMBAL) - Pleven Ltd., for a 5 year period (01.01.1999 - 31.12.2003) and an assessment of the effect of the disease on the fetus and the neonate. METHODS: Anamnesis, clinical investigation, serology, ultrasound of the fetus, cardiotocography, path morphology and statistical analysis. RESULTS: The retro- and prospective investigation made gives an idea of a slight tendency of increased frequency of pregnant women with positive serological probes, necessitating active treatment during pregnancy and after delivery (1999 - 0,32%, 2000 - 0,28%, 2001 - 0,51%, 2002 - 0,54% and 2003 - 0,65%). The most often inflicted contingent is among the illiterate population with a low social status. Frequency of obstetrical complication is not greater than with the seronegative women. Pronounced pathology in neonates is observed in newly diagnosed untreated cases. Frequency of operative delivery is independent of the accompanying disease. Higher among the diseased women is the incidence of premature, born-dead and death in the early neonatal period. CONCLUSION: From our results and data from literature we conclude as follows: 1. Wide screening of the sexually active population which covers the socially poor structures is necessary; 2. In timely started treatment with sufficient dose of Penicillin prophylaxis pevents complications to the fetus and the neonate; 3. Pertinent is the use of wide spectrum serological probes with pregnant women; 4. Changes in the health system have inferred a reduced efficacy of mass screening during pregnancy.

Adult↗
PubMed2003

Intracellular pH regulation in rainbow trout (Oncorhynchus mykiss) hepatocytes: the activity of sodium/proton exchange is oxygen-dependent.

We studied pH regulation in freshly isolated rainbow trout hepatocytes using microspectrofluorometry with the fluorescent dye BCECF. In accordance with earlier data on rainbow trout hepatocytes, ion substitution (N-methyl D-glucamine for sodium and gluconate for chloride) and transport inhibitor [10 microM M methyl isobutyl amiloride (MIA) to inhibit sodium/proton exchange and 100 microM DIDS to inhibit bicarbonate transport] studies in either Hepes-buffered or bicarbonate/carbon dioxide-buffered media (extracellular pH 7.6) indicated a role for sodium/proton exchange, sodium-dependent bicarbonate transport, and sodium-independent anion exchange in the regulation of hepatocyte pH. In Hepes-buffered medium, the activity of the sodium/proton exchanger (i.e. proton extrusion inhibited by MIA) was greater at 1% than at 21% oxygen. The oxygen dependency of the sodium/proton exchange is not caused by hydroxyl radicals, which appear to mediate the oxygen sensitivity of potassium-chloride cotransport in erythrocytes.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed2003

Oxygen dependency of the adrenergic Na/H exchange in rainbow trout erythrocytes is diminished by a hydroxyl radical scavenger.

AIM: Potassium transport via the potassium chloride cotransporter in rainbow trout erythrocytes is increased by high oxygen tension. It appears that the effect of oxygen is mediated by reactive oxygen species, especially hydroxyl radicals. In contrast, the activity of adrenergically stimulated sodium proton exchange decreases with increasing oxygen tension. As available data suggest that the two transporters are regulated reciprocally, the present study was undertaken to evaluate, if hydroxyl radicals may inhibit sodium transport via the adrenergically stimulated sodium proton exchanger. METHODS: The effects of the hydroxyl radical scavenger, 2 mm mercaptopropionyl glycine (MPG), on the activity of the adrenergically activated sodium proton exchange in rainbow trout erythrocytes were examined by measuring unidirectional sodium flux, using radioactive isotope, and cellular water content. RESULTS: The activity of the sodium proton exchange increased with decreasing oxygen tension after adrenergic stimulation. When MPG was present during incubation, there was no statistically significant effect of oxygen tension on the adrenergically stimulated sodium proton exchange, whereby the activity of the transporter at atmospheric oxygen tension was markedly higher in the presence than in the absence of MPG. In the absence of adrenergic stimulation, MPG did not influence the transporter activity significantly at any oxygen tension. CONCLUSION: The data suggest that hydroxyl radicals are involved in the inhibition of the adrenergically stimulated sodium proton exchange at elevated oxygen tensions.

Animals↗
PubMed2001

Photochemical ring opening of 7-benzoyl- and 7-methoxycarbonyldibenzonorcaradienes. competing 1,2-hydrogen shift and cyclization reactions of 1,3-diradicals.

[see reaction]. The UV irradiation of dibenzonorcaradienes bearing an acyl or alkoxycarbonyl substituent in the 7-position results in formation of substituted phenanthrenes, as well as cis-trans isomerization of the starting material. This reaction apparently proceeds via intermediate formation of a short-lived (tau = 1-20 ns) 1,3-diradical, which is produced by photochemical cleavage of one cyclopropane bond, while no evidence of alpha-carbonylcarbene formation was found.

Journal Article↗
PubMed2000

High-throughput profiling of the mitochondrial proteome using affinity fractionation and automation.

Recent studies have demonstrated the need for complementing cellular genomic information with specific information on expressed proteins, or proteomics, since the correlation between the two is poor. Typically, proteomic information is gathered by analyzing samples on two-dimensional gels with the subsequent identification of specific proteins of interest by using trypsin digestion and mass spectrometry in a process termed peptide mass fingerprinting. These procedures have, as a rule, been labor-intensive and manual, and therefore of low throughput. The development of automated proteomic technology for processing large numbers of samples simultaneously has made the concept of profiling entire proteomes feasible at last. In this study, we report the initiation of the (eventual) complete profile of the rat mitochondrial proteome by using high-throughput automated equipment in combination with a novel fractionation technique using minispin affinity columns. Using these technologies, approximately one hundred proteins could be identified in several days. In addition, separate profiles of calcium binding proteins, glycoproteins, and hydrophobic or membrane proteins could be generated. Because mitochondrial dysfunction has been implicated in numerous diseases, such as cancer, Alzheimer's disease and diabetes, it is probable that the identification of the majority of mitochondrial proteins will be a beneficial tool for developing drug and diagnostic targets for associated diseases.

Animals↗
PubMed2000

Molecular studies of the intestinal mucosal barrier physiopathology using cocultures of epithelial and immune cells: a technical update.

Peyer's patch lymphocytes cocultured with Caco-2 cells trigger the phenotypic conversion of enterocytes into cells that express morphological and functional M-cell properties. We report a technical update for setting up this model, which will enable the study of M-cell biology, the identification by biochemical approaches of molecules involved in the interaction of microorganisms with M cells, and the development of vectors that would efficiently target the mucosal immune system.

Animals↗
PubMed1998

Chloride transport in red blood cells of lamprey lampetra fluviatilis: evidence for a novel anion-exchange system

The existence of a furosemide-sensitive Cl- transport pathway activated by external Ca2+ and Mg2+ has been demonstrated previously in studies of Cl- influx across the lamprey erythrocyte membrane. The aim of the present study was to characterize further specific Cl- transport pathways, especially those involved in Cl- efflux, in the red blood cell membrane of Lampetra fluviatilis. Cl- efflux was inhibited by 0.05 mmol l-1 dihydroindenyloxyalkanoic acid (DIOA) (81 %), 1 mmol l-1 furosemide (76 %) and 0.1 mmol l-1 niflumic acid (54 %). Bumetanide (100 micromol l-1) and DIDS (100 micromol l-1) had no effect effect on Cl- efflux. Substitution of external Cl- by gluconate, but not by NO3-, led to a gradual decline of Cl- efflux. In addition, the removal of external Ca2+ resulted in a significant reduction in the rate of Cl- efflux. Membrane depolarization caused by increasing external K+ concentration or by inhibiting K+ channels with 1 mmol l-1 Ba2+ did not affect Cl- efflux. The furosemide-sensitive component of Cl- influx was a saturable function of external [Cl-] with an apparent Km of approximately 92 mmol l-1 and Vmax of approximately 17.8 mmol l-1 cells-1 h-1. Furosemide did not affect intracellular Cl- concentration (57.6+/-5. 2 mmol l-1 cell water), measured using an ion-selective Cl- electrode, showing that a furosemide-sensitive pathway is not involved in net Cl- movement. A gradual fall (from 28.1+/-1.4 to 15. 0+/-1.3 mmol l-1 cells-1 h-1) in unidirectional Cl- influx with time was observed within 3 h of cell preincubation in the standard physiological medium. These data provide evidence for the existence for an electroneutral furosemide-sensitive anion-exchange pathway in the lamprey erythrocyte membrane that accepts chloride and nitrate, but not bicarbonate or bromide.

Journal Article↗
PubMed1997

Conversion by Peyer's patch lymphocytes of human enterocytes into M cells that transport bacteria.

The epithelium that lines the gut is impermeable to macromolecules and microorganisms, except in Peyer's patches (PPs), where the lymphoid follicle-associated epithelium (FAE) contains M cells that transport antigens and microorganisms. A cultured system that reproduces the main characteristics of FAE and M cells was established by cultivation of PP lymphocytes with the differentiated human intestinal cell line Caco-2. Lymphocytes settled into the epithelial monolayer, inducing reorganization of the brush border and a temperature-dependent transport of particles and Vibrio cholerae. This model system could prove useful for intestinal physiology, vaccine research, and drug delivery studies.

Animals↗
PubMed1997

Paramagnetic metal scavenging by melanin: MR imaging.

PURPOSE: To quantitate the binding of metals to synthetic melanin in vitro, which is believed to be the reason why melanotic melanomas are hyperintense on T1-weighted magnetic resonance (MR) images, and to test whether such binding by natural melanin can be detected in cultured melanoma cells in vivo with MR imaging. MATERIALS AND METHODS: Seven synthetic metallomelanins were prepared and their metal contents and relaxivities determined. Melanotic PC1A and amelanotic B16 melanoma cells were incubated with increasing concentrations of iron. MR images of synthetic melanin and cell phantoms were obtained. RESULTS: The iron-binding capacities and relaxivities of the different synthetic metallomelanins varied considerably, which reflects the heterogeneous structure of melanin and the complexity of its binding of metals. Nevertheless, the MR signal intensities of the synthetic melanin and cell phantoms show marked increases that scale, respectively, with increasing iron content and iron concentration in the incubation medium. CONCLUSION: Melanotic melanomas are hyperintense on T1-weighted images because of paramagnetic metal scavenging. This observation has implications for the interpretation of MR images, the improved detection of melanomas, and the development of imaging marker genes.

Animals↗
PubMed1997

MR imaging and scintigraphy of gene expression through melanin induction.

PURPOSE: To determine whether an expression vector that encodes for human tyrosinase, the key enzyme in the melanin production pathway, can be used to image gene expression with magnetic resonance (MR) imaging and scintigraphy. MATERIALS AND METHODS: Mouse fibroblasts and human embryonal kidney cells were transfected with an expression vector that contained a complete complementary DNA sequence that encodes the human tyrosinase gene (pcDNA3tyr). Transfected cells were assayed for messenger RNA presence, melanin staining, and indium-111 binding; scintigraphy and MR imaging were performed. RESULTS: Transfected cells contained tyrosinase messenger RNA and stained positively for melanin. Transfected cells had a higher In-111 binding capacity than nontransfected cells, a difference readily detectable with scintigraphy. MR imaging showed transfected cells to have markedly higher signal intensity after gene transfer than nontransfected cells. CONCLUSION: Gene transfer and expression in cell culture can be detected with MR imaging and scintigraphy. The proposed strategy of using an imaging marker gene may have a substantial effect on the noninvasive imaging of gene therapy.

Animals↗