Resistance to vitamin D has been known for decades as vitamin D resistant rickets, caused by mutations of the gene encoding for vitamin D receptor (VDR). Findings of extra-skeletal effects of vitamin D and learning of the molecular mechanisms used by its biologically active metabolite calcitriol revealed other ways leading to its impaired sensitivity. Calcitriol takes advantage of both genomic and non-genomic mechanisms through its binding to vitamin D receptor, located not only in the cell nuclei but also in a perinuclear space. On the genomic level the complex of calcitriol bound to VDR binds to the DNA responsive elements of the controlled gene in concert with another nuclear receptor, retinoid X receptor, and expression of the VDR itself is controlled by its own ligand. These elements were found not only in the promotor region, but are scattered over the gene DNA. The gene expression includes a number of nuclear transcription factors which interact with the responsive elements and with each other and learning how they operate would further contribute to revealing causes of the impaired vitamin D sensitivity. Finally, the examples of major disorders are provided, associated with impairment of the vitamin D function and its receptor., L. Máčová, M. Bičíková, R. Hampl., and Obsahuje bibliografii
The electrical properties of the supported lipid bilayer membrane (s-BLM) of egg phosphatidylcholine (PC) selfassembled on agar surface were examined. To characterize the insulating properties of s-BLMs, electrochemical impedance spectroscopy (EIS) was used. The analysis of impedance spectra in terms of an equivalent circuit of agar/electrolyte and agar/s-BLM/electrolyte in the frequency range of 0.1 Hz-10 kHz was performed. The high-density lipoproteins (HDL)/s-BLM interaction in the concentration range from 20 μg/ml to 80 μg/ml of HDL was investigated. It is evident that treatment of s-BLM with HDL resulted in an increase of the lipid film resistance and a decrease of membrane capacitance., M. Legiň, G. Laputková, J. Sabo, L. Vojčíková., and Obsahuje bibliografii
There are five subtypes of muscarinic receptors that serve various important physiological functions in the central nervous system and the periphery. Mental functions like attention, learning, and memory are attributed to the muscarinic M1 subtype. These functions decline during natural aging and an early deficit is typical for Alzheimer´s disease. In addition, stimulation of the M1 receptor increases non-amyloidogenic processing of the amyloid precursor protein and thus prevents accumulation of noxious β-amyloid fragments. The selectivity of classical muscarinic agonists among receptor subtypes is very low due to the highly conserved nature of the orthosteric binding site among receptor subtypes. Herein we summarize some recent studies with the functionally-selective M1 agonist xanomeline that indicate complex pharmacological profile of this drug that includes interactions with and activation of receptor from both orthosteric and ectopic binding sites, and the time-dependent changes of ligand binding and receptor activation. These findings point to potential profitability of exploitation of ectopic ligands in the search for truly selectiev muscarinic receptor agonists., J. Jakubík, P. Michal, E. Machová, V. Doležal., and Obsahuje bibliografii a bibliografické odkazy
There is a growing interest for the beneficial effect of magnesium (Mg) in cardiovascular disorders. A number of cardiovascular disorders including myocardial infarction, arrhythmias and congestive heart failure have been associated with low extracellular or intracellular concentrations of Mg. The efficiency of the preconditioning effect of Mg on cardiac function and infarct size in the globally ischemic-reperfused isolated rat heart was studied together with the role of ATP-sensitive potassium (KATP) channels in protection induced by Mg. Rat hearts were Langendorff perfused, subjected to 30 min of global ischemia and 90 min of reperfusion, including treatment groups which focused on different times of Mg (8 mmol/l) use. Infarct size was measured by triphenyltetrazolium chloride (TTC) method. The left ventricular function was assessed by left ventricular developed pressure (LVDP), heart rate (HR) and coronary flow (CF). The administration of Mg before ischemia had an anti-infarct effect in rat hearts and improved cardiac function. The protective effects of magnesium was abolished by the blocking of KATP channels and suggests that K-ATP channel has an important role in the heart protection effect of Mg as a preconditioning agent., M. Bazargan, M. Faghihi, M. Chitsaz., and Obsahuje bibliografii a bibliografické odkazy
Autophagy is the basic catabolic mechanism that involves degradation of dysfunctional cellular components through the action of lysosome as well as supplying energy and compounds for the synthesis of essential biomacromolecules. This process enables cells to survive stress from the external environment like nutrient deprivation. Autophagy is important in the breakdown of proteins, carbohydrates and lipids as well. Furthermore, recent studies have shown that autophagy is critical in wide range of normal human physiological processes, and defective autophagy is associated with diverse diseases, including lysosomal storage disease, myopathies, neurodegeneration and various metabolic disorders. This review summarizes the most up-to-date findings on what role autophagy plays in metabolism., Z. Papáčková, M. Cahová., and Obsahuje bibliografii
The electrical parameters of the cell membrane are mostly estimated employing ac methods. The measurement is based on the analysis of the current(s) flowing through an access resistance and the membrane. A current/potential transducer is used at the input of the device. The parameters of this transducer, especially its feedback capacity, degrades the accuracy of the measurement and hence diminishes the suppression of mutual influences of the individual parameters. The paper suggests a possible software correction and is supplemented by remarks for practical application., V. Rohlíček, F. Rech., and Obsahuje bibliografii
On March 4, 2017 at the age of 68, Sidney George Shaw (Sid) unexpectedly died from complications following surgery, only four years after retiring from the University of Bern. Trained in biochemistry at Oxford University, Sid had quickly moved into molecular pharmacology and became a key investigator in the field of enzyme biochemistry, vasoactive peptide research, and receptor signaling. Sid spent half his life in Switzerland, after moving to the University of Bern in 1984. This article, written by his friends and colleagues who knew him and worked with him during different stages of his career, summarizes his life, his passions, and his achievements in biomedical research. It also includes personal memories relating to a dear friend and outstanding scientist whose intellectual curiosity, humility, and honesty will remain an example to us all., M. Barton, H. J. Little, R. D. Vaughan-Jones, S. Daniels, M. R. Dashwood, J. C. Tsui., and Seznam literatury
Flavin7 (F7) is a nutritional supplement often taken by cancer patients in Central Europe during chemo- and radiation therapy. In this study, investigation of the antiproliferative and antiangiogenic activities of this supplement were performed. Flavin7 showed antiprolif erative activity in Jurkat as well as in HeLa cells. It significantly reduced the growth of both cancer cell lines at the doses of 200 μg/ml to 20 μg/ml (p<0.001 and p<0.01, respectively). In F7-treated Jurkat cells we found a significant increase in the fraction of cells with sub-G0/G1 DNA content, which is considered to be a marker of apoptotic cell death. Apoptosis was also confirmed by annexin V staining and DNA fragmentation. Furthermore, F7 at the doses of 100 μg/ml to 4 μg/ml inhibited endothelial cell migration and capillary tube formation what indicates its potential antiangiogenic properties. Flavin7 also inhibited the activity of matrix metalloproteinases (MMPs), preferentially MM P-9, at the doses of 100 μg/ml to 4 μg/ml. Our data suggest that F7 possesses marked antiproliferative and antiangiogenic properties in vitro. Further research is needed to elucidate also its in vivo activities., J. Mojžiš, M. Šarišský, M. Pilátová, V. Voharová, L. Varinská, G. Mojžišová, A. Ostro, P. Urdzík, R. Dankovčik, L. Mirossay., and Obsahuje bibliografii a bibliografické odkazy
The aim of this in vitro study was to examine the secretion activity (progesterone, 17β-estradiol and insulin-like growth factor-I) of rat ovarian fragments after molybdenum (Mo) addition. Rat ovarian fragments were incubated with ammonium molybdate (NH4)6Mo7O24.4H2O at the doses 90, 170, 330 and 500 μg.ml-1 for 24 h and compared with control group without Mo addition. Release of progesterone (P4), estradiol (17β-estradiol) and insulin-like growth factor I (IGF-I) by ovarian fragments was assessed by radioimmunoassay (RIA). Data show that P4 release by ovarian fragments was not affected by (NH4)6.Mo7O24.4H2O addition at all the doses used (90-500 μg.ml-1). However, addition of ammonium molybdate was found to cause a significant (P<0.05) dose-dependent decrease (at the doses 90, 170 and 500 μg.ml-1) in release of 17β-estradiol by ovarian fragments in comparison to control. Also, addition of ammonium molybdate significantly (P<0.05) inhibited IGF-I release at all the doses (90-500 μg.ml-1) used in the study. Results suggest ammonium molybdate induced inhibition in the release of growth factor IGF-I and its dosedependent effect on secretion of steroid hormone 17β-estradiol but not progesterone. These data contribute to new insights regarding the mechanism of action of Mo on rat ovarian functions., S. Roychoudhury, L. Detvanova, A. V. Sirotkin, R. Toman, A. Kolesarova., and Obsahuje bibliografii
Skin healing process is postnatally always associated with scarring of various extent. Based on the clinical experience of plastic surgeons, the healing after lip cleft reconstruction is surprisingly almost scar-less when it is carried out within a few first days after birth. This phenomenon is not seen in delayed cases. In order to decipher causative mechanism, we have isolated and studied principal cell populations, keratinocytes and fibroblast, from residual tissue samples after reconstructive operation (N=39) performed at various age (0-9 years). These cells play the pivotal role in the healing and that is why we focused on description of their phenotype and also functionality with respect to age. We have identified a population of remarkably small cells in explants from newborns (day 0-10). These small cells were strongly positive for markers of low differentiated keratinocytes, keratin-8 and -19, and moreover also for vimentin. In the explants cultures from older babies this population was missing. Fibroblasts from newborns and older patients differed namely in terms of nestin expression and also in the production of extracellular matrix components. We conclude that in vitro described properties of keratinocytes and fibroblasts in newborns could participate on the almost scar-less wound healing in earliest neonatal period., E. Krejčí, O. Kodet, P. Szabo, J. Borský, K. Smetana Jr., M. Grim, B. Dvořánková., and Obsahuje bibliografii