Ivan Miksik - Academia.edu (original) (raw)

Papers by Ivan Miksik

Ecological Chemistry and Engineering S-chemia I Inzynieria Ekologiczna S, 2010

Age-related colour changes of biological objects are the results of changes in structure and prop... more Age-related colour changes of biological objects are the results of changes in structure and properties which may reflect the influence of the extrinsic and intrinsic environment. The method able to discriminate these two factors was not published yet. Non-erupted teeth which are isolated from the environment of the oral cavity (intrinsic factors) have not yet been explored too. A device for research the dentist’s chair-side measurements of vital erupted teeth as well as extracted impacted teeth (immediately after extraction) was built from commercially supplied components (fiber optic spectrometer) coupled with specific custom-made parts and a specific software driver. The measurement method related tooth for total colour changes in system CIELAB 1976 was evaluated to be inadequate. For more precise method of the ∆ECMC(l:c) were theoretical trichromatic coordinates of standard tooth and the ratio of extrinsic and intrinsic factors for vital erupted and impacted teeth modelled by mu...

Journal of chromatography. B, Analytical technologies in the biomedical and life sciences, 2004

A high-performance liquid chromatography-atmospheric pressure ionization-electrospray ionization ... more A high-performance liquid chromatography-atmospheric pressure ionization-electrospray ionization mass spectrometry (HPLC-API-ESI-MS) method was developed for the analysis of steroids in a study of steroid-converting enzymes. Separations ware done on a Zorbax Eclipse XDB-C18 column (eluted with a linear methanol-water-acetic acid gradient) and identification of the steroids involved was done by API-ESI-MS using positive ion mode and extracted ion analysis. The applicability of the present method for studying steroid metabolism was proven in assaying two steroid-converting enzymes (20beta-hydroxysteroid dehydrogenase and 11beta-hydroxysteroid dehydrogenase) in various biological samples (rat and chicken intestine, chicken oviduct).

Progress in Neuro-Psychopharmacology and Biological Psychiatry

Lithium (Li) is a typical mood stabilizer and the first choice for treatment of bipolar disorder ... more Lithium (Li) is a typical mood stabilizer and the first choice for treatment of bipolar disorder (BD). Despite an extensive clinical use of Li, its mechanisms of action remain widely different and debated. In this work, we studied the time-course of the therapeutic Li effects on ouabain-sensitive Na+/K+-ATPase in forebrain cortex and hippocampus of rats exposed to 3-day sleep deprivation (SD). We also monitored lipid peroxidation as malondialdehyde (MDA) production. In samples of plasma collected from all experimental groups of animals, Li concentrations were followed by ICP-MS. The acute (1 day), short-term (7 days) and chronic (28 days) treatment of rats with Li resulted in large decrease of Na+/K+-ATPase activity in both brain parts. At the same time, SD of control, Li-untreated rats increased Na+/K+-ATPase along with increased production of MDA. The SD-induced increase of Na+/K+-ATPase and MDA was attenuated in Li-treated rats. While SD results in a positive change of Na+/K+-ATPase, the inhibitory effect of Li treatment may be interpreted as a pharmacological mechanism causing a normalization of the stress-induced shift and return the Na+/K+-ATPase back to control level. We conclude that SD alone up-regulates Na+/K+-ATPase together with increased peroxidative damage of lipids. Chronic treatment of rats with Li before SD, protects the brain tissue against this type of damage and decreases Na+/K+-ATPase level back to control level.

Molecular and cellular biochemistry, Jan 4, 2018

The heart is characterized by a remarkable degree of heterogeneity. Since different cardiac patho... more The heart is characterized by a remarkable degree of heterogeneity. Since different cardiac pathologies affect different cardiac regions, it is important to understand molecular mechanisms by which these parts respond to pathological stimuli. In addition to already described left ventricular (LV)/right ventricular (RV) and transmural differences, possible baso-apical heterogeneity has to be taken into consideration. The aim of our study has been, therefore, to compare proteomes in the apical and basal parts of the rat RV and LV. Two-dimensional electrophoresis was used for the proteomic analysis. The major result of this study has revealed for the first time significant baso-apical differences in concentration of several proteins, both in the LV and RV. As far as the LV is concerned, five proteins had higher concentration in the apical compared to basal part of the ventricle. Three of them are mitochondrial and belong to the "metabolism and energy pathways" (myofibrillar c...

Ecology and Evolution, 2016

This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Journal of Chromatography Library, 2003

Life Sci, 1994

Summarv Aldosterone selectivity of mineralocorticoid target tissues has been suggested to be due ... more Summarv Aldosterone selectivity of mineralocorticoid target tissues has been suggested to be due to the inactivation of glucocorticoids in the target tissue by 11/3-hydroxysteroid dehydrogenase (11/~-OHSD). The distribution of 11/~-OHSD was studied in the intestine which is composed of aldosterone-sensitive and insensitive segments. The activity of the enzyme was high in distal colon and medium in ileum, cecum, and proximal colon. Zero activity was found in duodenum and jejunum. Carbenoxolone completely blocked the enzyme. Low-salt diet increased the activity in proximal colon and decreased in ileum. Adrenalectomy decreased the activity in ileum and proximal colon. The existence of segmental differences in the distribution of 11/3-OHSD and the hormonal effect on the activity of the enzyme suggest a physiological role of 11/~-OHSD in the intestine.

American Journal of Hypertension, 2003

Journal of Chromatography a, 1995

Microemulsion electrokinetic chromatography (MEEKC) was carried out in a pH 2.5 phosphate buffer ... more Microemulsion electrokinetic chromatography (MEEKC) was carried out in a pH 2.5 phosphate buffer to effectively suppress the electroosmotic flow (EOF). With 66.6% (w/w) 25 mM phosphate buffer pH 2.5, 20.0% (w/w) 2-propanol, 6.6% ...

J Steroid Biochem Mol Biol, 2008

J Steroid Biochem Mol Biol, 2005

Corticosteroids have been shown to play a role in cardiac remodeling, with the possibility of a d... more Corticosteroids have been shown to play a role in cardiac remodeling, with the possibility of a direct effect of overexpression of 11␤hydroxysteroid dehydrogenase (11HSD) isoform 2 at the level of the cardiomyocytes. The aim of this study was to examine cardiac steroid metabolism in hypertensive rats with hearts that are hypertrophied and fibrotic and have structural alterations in the coronary circulation. To assess possible alterations of cardiac steroid metabolism the expression and activity of both isoforms of 11␤-hydroxysteroid dehydrogenase (11HSD) were studied in spontaneously hypertensive rats (SHR), their normotensive controls Wistar-Kyoto (WKY), and in Dahl salt-sensitive (DS) and salt-resistant rats (DR) kept on a low-or high-salt diet. Using real-time quantitative RT-PCR and enzyme activity assay we found strain-dependent differences in cardiac metabolism of glucocorticoids. In Dahl rats expression of 11HSD1 and 11HSD2 mRNA was lower in DS than in DR rats and was not influenced by dietary salt intake; 11HSD1 mRNA was expressed at higher level than 11HSD2 mRNA. NADP +-dependent cardiac 11HSD activity showed similar distribution as 11HSD1 mRNA-lower activity in DS than in DR rats and no effect of salt intake. In SHR and WKY strains 11HSD2 mRNA expression was significantly higher in WKY than in SHR but no differences were observed in 11HSD1 mRNA abundance and NADP +-dependent 11HSD activity. These results show that the heart is able to metabolize glucocorticoids and that this metabolism is strain-dependent but do not support the notion of association between cardiac hypertrophy and changes of 11HSD1 and 11HSD2 expression.

J Chromatogr a, 1998

A mixture of saturated fatty acids containing even number of carbon atoms was successfully separa... more A mixture of saturated fatty acids containing even number of carbon atoms was successfully separated as phenacyl esters by microemulsion electrokinetic chromatography. Separations were done by using an untreated fused-silica capillary [57 cm (effective length 50 cm)375 mm] at 15 kV; detection was done by UV at 243 nm. The microemulsion system was composed of 10 mM borate buffer (87.93%, w / w), cholate (4.87%, w / w), heptane (0.66%, w / w) and n-butanol (6.55%, w / w), pH 10.2. Separation by microemulsion electrokinetic chromatography was characterized by high efficiency (theoretical plates 3 3 ranged from 142?10 to 428?10) with peak resolution 1.25 and better. Micellar electrokinetic chromatography under the standard conditions with sodium dodecyl sulfate as micellar phase was unsuccessful in separating all long-chain fatty acids. The described method can be used for monitoring of saturated fatty acids containing even number of carbon atoms in the molecule in a broad spectrum of chain length (C-C).

Ecology and evolution, Jan 12, 2016

No single hypothesis is likely to explain the diversity in eggshell coloration and patterning acr... more No single hypothesis is likely to explain the diversity in eggshell coloration and patterning across birds, suggesting that eggshell appearance is most likely to have evolved to fulfill many nonexclusive functions. By controlling for nonindependent phylogenetic associations between related species, we describe this diversity using museum eggshells of 71 British breeding passerine species to examine how eggshell pigment composition and concentrations vary with phylogeny and with life-history and nesting ecology traits. Across species, concentrations of biliverdin and protoporphyrin, the two main pigments found in eggshells, were strongly and positively correlated, and both pigments strongly covaried with phylogenetic relatedness. Controlling for phylogeny, cavity-nesting species laid eggs with lower protoporphyrin concentrations in the shell, while higher biliverdin concentrations were associated with thicker eggshells for species of all nest types. Overall, these relationships betwe...

Clanek popisuje zakladni principy fotografovani ptaků v letu. Podrobně jsou zde rozebrany dva zak... more Clanek popisuje zakladni principy fotografovani ptaků v letu. Podrobně jsou zde rozebrany dva zakladni přistupy – klasický (tradicni), využivajici kratkeho expozicniho casu, a “experimentalni“, využivajici dlouheho expozicniho casu. Nazorně je zde předvedeno jak použiti panning techniky, tak i přisvětleni bleskem ci připadně jejich kombinace.

Journal of Chromatography B

INTRODUCTION: The activity of placental 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) protec... more INTRODUCTION: The activity of placental 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) protects the fetus from overexposure to endogenous glucocorticoids (GCs) by converting cortisol and corticosterone into their inactive keto-derivates cortisone and 11 dehydrocorticosterone, respectively. AIM OF THE STUDY: In our study we investigated the effect of antenatal GC administration on the expression and functional activity of 11β-HSD2 in the human choriocarcinoma cell line JEG3 and rat placenta. We focused particularly on dexamethasone (DXM) and betamethasone (BTM) since these synthetic GCs are routinely administered to pregnant woman at risk of preterm delivery to enhance fetal lung maturation. METHODS: JEG3 cells were incubated with either DXM or BTM in concentrations ranging from 10-9 to 10-6 nM for 24 or 48 hours. In animal studies pregnant rats were premedicated with five i.m. doses of either DXM (200g/kg or 5mg/kg) or BTM (200g/kg or 11.5mg/kg) in 24 hour intervals at 16-21 ges...