127 results on '"Jan Vacek"'
Search Results
2. Cannabidiol and periodontal inflammatory disease: A critical assessment
- Author
-
Petr Jirasek, Alexandr Jusku, Vilim Simanek, Jana Frankova, Jan Storch, and Jan Vacek
- Subjects
Mammals ,Analgesics ,Receptor, Cannabinoid, CB1 ,Cannabinoids ,Animals ,Cannabidiol ,Humans ,Periodontal Diseases ,General Biochemistry, Genetics and Molecular Biology - Abstract
Cannabidiol (CBD), a non-psychotropic cannabinoid produced by the genus Cannabis, is a phytoceutical that activates the endocannabinoid system (ECS) through binding to CB1 and CB2 receptors. The ECS is involved in cellular homeostasis and regulates metabolic processes in virtually all mammalian tissues. Published studies on CBD focus, inter alia, on its use in prophylaxis and as an anti-inflammatory agent. Here the authors present a critical assessment of the effects of CBD on inflammatory periodontal diseases caused by bacterial virulence factors, and evaluate critically the possible benefits and drawbacks of CBD use in dentistry. Particular attention is paid to the interaction of CBD with microbially colonized oral tissues, the inflammatory response in relation to the immune response, and the destruction/regeneration of hard and soft tissues of the periodontium.
- Published
- 2022
3. Lipid-based liquid crystalline materials in electrochemical sensing and nanocarrier technology
- Author
-
Martina Zatloukalova, Lukasz Poltorak, Renata Bilewicz, and Jan Vacek
- Subjects
Analytical Chemistry - Abstract
Some biologically active substances are unstable and poorly soluble in aqueous media, at the same time exhibiting low bioavailability. The incorporation of these biologically active compounds into the structure of a lipid-based lyotropic liquid crystalline phase or nanoparticles can increase or improve their stability and transport properties, subsequent bioavailability, and applicability in general. The aim of this short overview is (1) to clarify the principle of self-assembly of lipidic amphiphilic molecules in an aqueous environment and (2) to present lipidic bicontinuous cubic and hexagonal phases and their current biosensing (with a focus on electrochemical protocols) and biomedical applications. Graphical Abstract
- Published
- 2023
4. Serum albumin as a primary non-covalent binding protein for nitro-oleic acid
- Author
-
Lenka Hernychova, Eleni Alexandri, Andreas G. Tzakos, Martina Zatloukalová, Alexandra Primikyri, Ioannis P. Gerothanassis, Lukas Uhrik, Marek Šebela, David Kopečný, Lukáš Jedinák, and Jan Vacek
- Subjects
Tandem Mass Spectrometry ,Structural Biology ,Humans ,Oleic Acids ,General Medicine ,Carrier Proteins ,Nitro Compounds ,Molecular Biology ,Biochemistry ,Serum Albumin ,Oleic Acid ,Protein Binding - Abstract
This work explores the interaction of 9/10-nitro-oleic acid (NO
- Published
- 2022
5. Preparation, stability, and molecular modeling of nitro-oleic acid/cyclodextrin complexes under aqueous conditions
- Author
-
David Novak, Martina Zatloukalova, Lukas Jedinak, Bara Komarkova, Martin Kabelac, and Jan Vacek
- Subjects
Materials Chemistry ,Physical and Theoretical Chemistry ,Condensed Matter Physics ,Spectroscopy ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Published
- 2023
6. Flavin‐Helicene Amphiphilic Hybrids: Synthesis, Characterization, and Preparation of Surface‐Supported Films
- Author
-
Adrianna Cytryniak, Renata Bilewicz, Jan Storch, Jeanne Crassous, Radek Cibulka, Ivana Císařová, Martin Jakubec, Jan Vacek, Jan Hrbac, David Novak, Ludovic Favereau, Martina Zatloukalová, Jaroslav Žádný, Institute of Chemical Process Fundamentals (ICPF), Czech Academy of Sciences [Prague] (CAS), Palacky University Olomouc, Charles University [Prague] (CU), University of Chemistry and Technology Prague (UCT Prague), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), University of Warsaw (UW), Masaryk University [Brno] (MUNI), Palacky University [RVO 61989592], Ministry of Education, Youth and Sports (MEYS, Czech Republic) [IGA_LF_2020_022], Czech Science Foundation Grant Agency of the Czech Republic [20-19353S], MEYS [CZ.02.2.69/0.0/0.0/16_027/0008482], project \'e-Infrastruktura CZ\' within the program \'Projects of Large Research, Development and Innovations Infrastructures\' within the program \'Projects of Large Research, Development and Innovations Infrastructures\' [eINFRA LM2018140], Institute of Chemical Process Fundamentals of the ASCR, Czech Republic, Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)
- Subjects
Circular dichroism ,thin layers ,lipidic cubic phases ,[CHIM.ORGA]Chemical Sciences/Organic chemistry ,010405 organic chemistry ,Chemistry ,Supramolecular chemistry ,Mesophase ,General Chemistry ,Flavin group ,010402 general chemistry ,flavins ,01 natural sciences ,0104 chemical sciences ,helicenes ,[CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry ,Crystallography ,chemistry.chemical_compound ,Helicene ,Amphiphile ,[CHIM]Chemical Sciences ,Molecule ,Cyclic voltammetry ,redox behavior - Abstract
International audience; This work reports on the preparation and structural characterization of flavo[7]helicene 1 (flavin-[7]helicene conjugate), which was subsequently characterized at the molecular level in either an aqueous environment or an organic phase, at the supramolecular level in the form of polymeric layers, and also embedded in a lipidic mesophase environment to study the resulting properties of such a hybrid relative to its parent molecules. The flavin benzo[g]pteridin-2,4-dione (isoalloxazine) was selected for conjugation because of its photoactivity and reversible redox behavior. Compound 1 was prepared from 2-nitroso[6]helicene and 6-methylamino-3-methyluracil, and characterized using common structural and spectroscopic tools: circular dichroism (CD), circularly polarized luminescence (CPL) spectroscopy, cyclic voltammetry (CV), and DFT quantum calculations. In addition, a methodology that allows the loading of 1 enantiomers into an internally nanostructured lipid (1-monoolein) matrix was developed.
- Published
- 2021
7. An Essay on Plausibility (Deconstruction) of Our Educational System
- Author
-
Jan Vacek
- Subjects
General Chemistry - Published
- 2023
8. Antioxidant function of phytocannabinoids: Molecular basis of their stability and cytoprotective properties under UV-irradiation
- Author
-
Martin Kabeláč, Denisa Skarupova, Jan Storch, Jan Vacek, Jitka Vostálová, Barbora Papoušková, and Martin Kos
- Subjects
0301 basic medicine ,Cannabigerol ,medicine.medical_treatment ,Pharmacology ,Biochemistry ,Antioxidants ,03 medical and health sciences ,chemistry.chemical_compound ,Cannabichromene ,HaCaT ,030104 developmental biology ,0302 clinical medicine ,chemistry ,Physiology (medical) ,medicine ,Cannabinol ,Cannabidiol ,Humans ,Dronabinol ,Cannabinoid ,Tetrahydrocannabinol ,Phototoxicity ,030217 neurology & neurosurgery ,medicine.drug - Abstract
In this contribution, a comprehensive study of the redox transformation, electronic structure, stability and photoprotective properties of phytocannabinoids is presented. The non-psychotropic cannabidiol (CBD), cannabigerol (CBG), cannabinol (CBN), cannabichromene (CBC), and psychotropic tetrahydrocannabinol (THC) isomers and iso-THC were included in the study. The results show that under aqueous ambient conditions at pH 7.4, non-psychotropic cannabinoids are slight or moderate electron-donors and they are relatively stable, in the following order: CBD > CBG ≥ CBN > CBC. In contrast, psychotropic Δ9-THC degrades approximately one order of magnitude faster than CBD. The degradation (oxidation) is associated with the transformation of OH groups and changes in the double-bond system of the investigated molecules. The satisfactory stability of cannabinoids is associated with the fact that their OH groups are fully protonated at pH 7.4 (pKa is ≥ 9). The instability of CBN and CBC was accelerated after exposure to UVA radiation, with CBD (or CBG) being stable for up to 24 h. To support their topical applications, an in vitro dermatological comparative study of cytotoxic, phototoxic and UVA or UVB photoprotective effects using normal human dermal fibroblasts (NHDF) and keratinocytes (HaCaT) was done. NHDF are approx. twice as sensitive to the cannabinoids’ toxicity as HaCaT. Specifically, toxicity IC50 values for CBD after 24 h of incubation are 7.1 and 12.8 μM for NHDF and HaCaT, respectively. None of the studied cannabinoids were phototoxic. Extensive testing has shown that CBD is the most effective protectant against UVA radiation of the studied cannabinoids. For UVB radiation, CBN was the most effective. The results acquired could be used for further redox biology studies on phytocannabinoids and evaluations of their mechanism of action at the molecular level. Furthermore, the UVA and UVB photoprotectivity of phytocannabinoids could also be utilized in the development of new cannabinoid-based topical preparations.
- Published
- 2021
9. Cysteamine assay for the evaluation of bioactive electrophiles
- Author
-
David Novak, Vlastimil Dorčák, Lenka Roubalová, Krzysztof Stolarczyk, Jiří Vrba, Jan Vacek, and Martina Zatloukalová
- Subjects
0301 basic medicine ,chemistry.chemical_classification ,Cysteamine ,Biochemistry ,Combinatorial chemistry ,Mass Spectrometry ,Chemical kinetics ,Kinetics ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,0302 clinical medicine ,chemistry ,Covalent bond ,Physiology (medical) ,Electrophile ,Thiol ,Amine gas treating ,Reactivity (chemistry) ,Sulfhydryl Compounds ,Molecular probe ,030217 neurology & neurosurgery ,Signal Transduction - Abstract
Covalent modifications of thiol and amine groups may control the function of proteins involved in the regulatory and signaling pathways of the cell. In this study, we developed a simple cysteamine assay which can be used to study the reactivity of electrophilic compounds towards primary amine and thiol groups in an aqueous environment. The detection principle is based on the electrochemical, photometrical and mass spectrometric analyses of cysteamine (2-aminoethanethiol) as the molecular probe. This technique is useful for studying the reaction kinetics of electrophiles with thiol (SH) and amino (NH2) groups. The decrease in analytical responses of cysteamine was monitored to evaluate the reactivity of three electrophilic activators of the Nrf2 pathway, which mediates the cellular stress response. The SH-reactivity under cell-free conditions of the tested electrophiles decreased in the following order: 4-hydroxy-2-nonenal ≥ nitro-oleic acid > sulforaphane. However, as shown in RAW264.7 cells, the tested compounds activated Nrf2-dependent gene expression in the opposite order: sulforaphane > nitro-oleic acid ≥ 4-hydroxy-2-nonenal. Although other factors in addition to chemical reactivity play a role in biological systems, we conclude that this cysteamine assay is a useful tool for screening potentially bioactive electrophiles and for studying their reactivity at a molecular level.
- Published
- 2021
10. Safety assessment and redox status in rats after chronic exposure to cannabidiol and cannabigerol
- Author
-
Hana Holcova Polanska, Katerina Petrlakova, Barbora Papouskova, Michal Hendrych, Amir Samadian, Jan Storch, Petr Babula, Michal Masarik, and Jan Vacek
- Subjects
Toxicology - Published
- 2023
11. A Systematic Review of Spatial Differences of the Ball Impact within the Serve Type at Professional and Junior Tennis Players
- Author
-
Michal Vágner, Petr Stastny, Daniel Cleather, and Jan Vacek
- Subjects
Fluid Flow and Transfer Processes ,Process Chemistry and Technology ,General Engineering ,General Materials Science ,Instrumentation ,Computer Science Applications - Abstract
Since the flat serve (FS) minimizes the ball spin and kick serve (KS) combined topspin and sidespin, this systematic review aimed to explore the ball impact location (BI) within the FS and KS at the professional men, junior men, and women tennis players. The PRISMA guideline was used, and the original articles were searched in Scopus, Web of Science, and PubMed. The means and standard deviations computed from the distance of BI from the origin within the FS and KS on the x, y, and z axes (global coordinate system) were normalized by the participants’ height and weighted by the number of participants in one-way ANOVA. Ten articles with a pooled sample of 133 males and 51 females aged 11–25 were included. The professional men had more stable BI on the x-axis within the FS by 56% (p < 0.001), within the KS by 58% (p < 0.001), and on the y-axis within the KS by 90% (p < 0.001) than junior men. The professional and junior men had the BI more leftwards from the origin on the x-axis within the KS by 188% (p < 0.001) and 88% (p < 0.001), respectively than within the FS.
- Published
- 2023
12. Sensors and microarrays in protein biomarker monitoring: an electrochemical perspective spots
- Author
-
Jan Hrbac and Jan Vacek
- Subjects
Protein biomarkers ,Computer science ,Clinical Biochemistry ,Nanotechnology ,Biosensing Techniques ,Electrochemical Techniques ,02 engineering and technology ,General Medicine ,Microarray Analysis ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,3. Good health ,Analytical Chemistry ,Biomarker (cell) ,Medical Laboratory Technology ,Humans ,Bipolar electrochemistry ,Multiplex ,General Pharmacology, Toxicology and Pharmaceutics ,DNA microarray ,0210 nano-technology ,Biomarkers - Abstract
The development of clinically applicable portable sensors and multiplex protein biomarker assays is one of the most important goals of laboratory medicine today. Sensing strategies based on electrochemical devices are discussed in this overview, with special emphasis on detection principles derived from voltammetry, electrogenerated chemiluminescence, bipolar electrochemistry and impedance-based measurements. Up-to-date examples of electrochemical methods in biomedical research and development are highlighted here, including critical evaluation and future directions of the analysis, development and validation of new protein biomarkers.
- Published
- 2020
13. Redox biology and electrochemistry. Towards evaluation of bioactive electron donors and acceptors
- Author
-
Jan Vacek, Martina Zatloukalova, and Martin Kabelac
- Subjects
Electrochemistry ,Analytical Chemistry - Published
- 2022
14. Oleic and nitro-oleic acid behavior at an electrified water-1,2-dichloroethane interface
- Author
-
Karolina Sobczak, Konrad Rudnicki, Lukas Jedinak, Martina Zatloukalova, Jan Vacek, and Lukasz Poltorak
- Subjects
Materials Chemistry ,Physical and Theoretical Chemistry ,Condensed Matter Physics ,Spectroscopy ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials - Published
- 2022
15. Ultrasound-guided sacroiliac joint injection
- Author
-
Jan Vacek, Karolína Sobotová, Šimon Kozák, Ondřej Naňka, Tomáš Novotný, and Karel Mezian
- Subjects
business.industry ,Sacroiliac joint injection ,Medicine ,Surgery ,Neurology (clinical) ,Nuclear medicine ,business ,Ultrasound guided - Published
- 2021
16. Structures of Peptidic H‐wires at Mercury Surface: Molecular Dynamics Study
- Author
-
Martin Kabeláč, Vlastimil Dorčák, Ondřej Kroutil, and Jan Vacek
- Subjects
Molecular dynamics ,chemistry ,Chemical physics ,Electrochemistry ,chemistry.chemical_element ,Helical peptide ,Analytical Chemistry ,Mercury (element) - Published
- 2019
17. Electrochemistry of peptides
- Author
-
Slawomir Sek, Vlastimil Dorčák, and Jan Vacek
- Subjects
chemistry.chemical_classification ,Peptide nucleic acid ,Antimicrobial peptides ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Combinatorial chemistry ,Redox ,0104 chemical sciences ,Analytical Chemistry ,Amino acid ,chemistry.chemical_compound ,chemistry ,Molecule ,0210 nano-technology - Abstract
This opinion is focused on the electrochemistry of peptides utilised in biological and technological processes. The redox behaviour of peptides important in biomedicine, neuropeptides and antimicrobial peptides is highlighted. In addition to peptides composed of essential amino acids, peptide-mimetic molecules such as peptide nucleic acid and artificial peptidic wires transferring protons and electrons are reviewed. The application of electrochemistry for the research of peptide–membrane and peptide–surface interactions is also discussed.
- Published
- 2019
18. Preparation and Physicochemical Properties of [6]Helicenes Fluorinated at Terminal Rings
- Author
-
Ivana Císařová, Tomáš Strašák, Jan Sýkora, Vladimír Církva, Jan Storch, Jan Vacek, Pavel Jakubík, Jan Hrbac, and Jaroslav Žádný
- Subjects
010405 organic chemistry ,Organic Chemistry ,Intermolecular force ,Crystal structure ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,3. Good health ,Crystallography ,chemistry.chemical_compound ,chemistry ,Helicene ,Yield (chemistry) ,Wittig reaction ,Specific rotation ,Cyclic voltammetry ,Racemization - Abstract
The first racemization-stable helicene derivatives fluorinated at terminal rings, 1,2,3,4-tetrafluoro[6]helicene (6) and 1,2,3,4,13,14,15,16-octafluoro[6]helicene (15), were synthesized via the Wittig reaction followed by oxidative photocyclization in an overall yield of 41% of 6 and 76% of 15. The changed electronic structure in fluorinated helicenes was reflected in a slight shift of UV-vis absorption, fluorescence excitation, and emission spectra maxima when compared to unsubstituted [6]helicene. Cyclic voltammetry revealed a moderate decrease in the HOMO-LUMO gap with increasing fluorination. The specific rotation of tetrafluoro[6]helicene 6 enantiomers was found to be approximately 25% lower than that of unsubstituted [6]helicene. The theoretical study of the racemization barrier suggested a reasonable shift toward higher energy with increasing fluorination. The increasing fluorination also significantly affected the intermolecular interactions in the crystal lattice. The observed CH···F interactions led to the formation of 1D-molecular chains in the crystal structures of both fluorinated helicenes.
- Published
- 2019
19. Free and bound histidine in reactions at mercury electrode
- Author
-
Luděk Havran, Jan Vacek, and Vlastimil Dorčák
- Subjects
General Chemical Engineering ,Electrochemistry ,Analytical Chemistry - Published
- 2022
20. Cyclopentenedione-based ascorbate-rejecting permselective layers prepared by electropolymerization
- Author
-
David Novosad, Miroslava Hrenakova, Jan Vacek, Jan Storch, Jakub Styskala, and Jan Hrbac
- Subjects
General Chemical Engineering ,Electrochemistry ,Analytical Chemistry - Published
- 2022
21. Electrochemistry of membrane proteins and protein–lipid assemblies
- Author
-
Martina Zatloukalová, David Novak, and Jan Vacek
- Subjects
chemistry.chemical_classification ,02 engineering and technology ,Polymer ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,Combinatorial chemistry ,Redox ,0104 chemical sciences ,Analytical Chemistry ,Membrane ,Enzyme ,Protein structure ,chemistry ,Membrane protein ,0210 nano-technology ,Biosensor - Abstract
Summary The electrochemistry of membrane proteins allows us to examine the association of proteins with membranes and low-molecular ligands, such as drugs, toxins and others. In addition, electrochemical methods are applicable for the quantification of transport phenomena, for monitoring the change in the structure of the protein, and determining its catalytic activity if the protein is an enzyme. In addition to approaches based on the concept of protein film voltammetry, methods based on the direct redox transformations or electrocatalytic reactions of the amino acid residues in the protein structure could be used. The above areas of interest fall under basic research, which is the main subject of this paper. However, the utilization of new immobilization strategies for proteins and the application of redox active polymers is an important part of the development of new biosensors and the construction of devices employing the principles of bioelectrocatalysis.
- Published
- 2018
22. Key Mismatch Attack on ThreeBears, Frodo and Round5
- Author
-
Jan Václavek and Jan Vacek
- Subjects
050101 languages & linguistics ,Post-quantum cryptography ,Computer science ,business.industry ,05 social sciences ,Cryptography ,02 engineering and technology ,Computer security ,computer.software_genre ,law.invention ,law ,Ciphertext ,0202 electrical engineering, electronic engineering, information engineering ,Key (cryptography) ,Cryptosystem ,020201 artificial intelligence & image processing ,0501 psychology and cognitive sciences ,Key encapsulation ,Cryptanalysis ,business ,computer ,Learning with errors - Abstract
In the last years, several key reuse attacks were proposed against Round 2 candidates of the NIST Post-Quantum Cryptography Standardization Process. In these attacks, the adversary has access to the key mismatch oracle which tells her if a given ciphertext decrypts to a given message under the targeted secret key. One of the so far non-targeted candidates is ThreeBears, which is a key encapsulation mechanism based on the integer module learning with errors (I-MLWE) problem. In this paper, we present a first key mismatch attack against the ThreeBears cryptosystem. Our attack recovers the whole secret key with probability of 100% and requires about \(2^{11}\) queries on average. Besides that, we use our technique to target other Round 2 candidates Frodo and Round5, and we improve the state-of-the-art results for them.
- Published
- 2021
23. Chiral Electrochemistry: Anodic Deposition of Enantiopure Helical Molecules
- Author
-
Jan Hrbac, Jan Vacek, Jan Storch, and Jaroslav Zadny
- Subjects
chemistry.chemical_classification ,Materials science ,Nanostructure ,010405 organic chemistry ,Nanotechnology ,General Chemistry ,Polymer ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Enantiopure drug ,Helicene ,chemistry ,Molecule ,Chirality (chemistry) ,Molecular imprinting - Abstract
Chirality is a fascinating phenomenon for recent electrochemistry and materials research, allowing for the preparation of detection platforms based on analyte enantiodiscrimination and the development of advanced chiroptical devices and chiral electrodes. In this Viewpoint, we highlight new directions in the field of chiral helical polyaromatic molecules (mainly helicenes) that are useful for the preparation of optically and redox-active polymers and/or self-assembled thin layers, nanostructures and functional electrode surfaces. Instead of the previously reported chiral materials prepared by molecular imprinting, a concept based on the preparation of inherently chiral helicene-based materials with (opto)electrochemical applicability is presented. A short overview of well-established electrochemical methods for the research of chiral molecules is also outlined.
- Published
- 2020
24. Bioelektrochemie
- Author
-
Jan Vacek and Veronika Ostatná
- Published
- 2020
25. Analytical techniques for multiplex analysis of protein biomarkers
- Author
-
Marei Sammar, Alain J. van Gool, Petra Martin, Virginie Brun, Theo M. Luider, Mirjana B. Čolović, Izabela Burzynska-Pedziwiatr, Felicia Antohe, Jaroslav Katrlík, Eda Aydindogan, Deborah Penque, Suna Timur, Jan Vacek, Guillaume Suarez, Zanka Bojic-Trbojevic, Chris W. Sutton, Ivone Jakasa, Ines Lanca Martins, Ede Bodoki, Danijela Krstić, Begona Oliver-Martos, Ruben t’Kindt, John Allinson, Lucyna A. Wozniak, Goran Gajski, César Pascual García, Kyriacos Kyriacou, Alicia Llorente, Viorel Iulian Suica, Saara Wittfooth, Bogdan-Cezar Iacob, Eva Martínez-Cáceres, Fernado Corrales, Stephan Nierkens, and European Cooperation in Science and Technology
- Subjects
0301 basic medicine ,Pharmaceutical drug ,Proteomics ,Protein biomarkers ,Multiplexing ,medicine.medical_treatment ,Computational biology ,Biochemistry ,Mass Spectrometry ,03 medical and health sciences ,mass spectrometry ,Validation ,medicine ,Animals ,Humans ,validation ,Multiplex ,Molecular Biology ,Immunoassay ,030102 biochemistry & molecular biology ,business.industry ,Metabolic Disorders Radboud Institute for Molecular Life Sciences [Radboudumc 6] ,3. Good health ,Genómica Funcional e Estrutural ,030104 developmental biology ,Personalized medicine ,business ,Biomarkers - Abstract
© 2020 The Author(s)., [Introduction]: The importance of biomarkers for pharmaceutical drug development and clinical diagnostics is more significant than ever in the current shift toward personalized medicine. Biomarkers have taken a central position either as companion markers to support drug development and patient selection, or as indicators aiming to detect the earliest perturbations indicative of disease, minimizing therapeutic intervention or even enabling disease reversal. Protein biomarkers are of particular interest given their central role in biochemical pathways. Hence, capabilities to analyze multiple protein biomarkers in one assay are highly interesting for biomedical research. [Areas covered]: We here review multiple methods that are suitable for robust, high throughput, standardized, and affordable analysis of protein biomarkers in a multiplex format. We describe innovative developments in immunoassays, the vanguard of methods in clinical laboratories, and mass spectrometry, increasingly implemented for protein biomarker analysis. Moreover, emerging techniques are discussed with potentially improved protein capture, separation, and detection that will further boost multiplex analyses. [Expert commentary]: The development of clinically applied multiplex protein biomarker assays is essential as multi-protein signatures provide more comprehensive information about biological systems than single biomarkers, leading to improved insights in mechanisms of disease, diagnostics, and the effect of personalized medicine., This paper was funded by the European cooperation in science and technology - COST action No. CA16113 - CliniMARK: ‘good biomarker practice’ to increase the number of clinically validated biomarkers.
- Published
- 2020
26. Positioning Techniques to Improve the Ultrasound Evaluation of the Elbow
- Author
-
Ali Zavareh, Stanislav Machač, Lucia Majerníková, Jan Vacek, Marc Schmitz, Kamal Mezian, and Leoš Navrátil
- Subjects
medicine.medical_specialty ,030219 obstetrics & reproductive medicine ,business.industry ,Elbow ,Ultrasound ,medicine.disease ,Sitting ,Patient Positioning ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,medicine.anatomical_structure ,Physical medicine and rehabilitation ,Elbow Joint ,mental disorders ,Humans ,Medicine ,Radiology, Nuclear Medicine and imaging ,Joint Diseases ,business ,Vasovagal syncope ,Ultrasonography - Abstract
We introduce an ergonomic positioning for sonographic scanning of elbow joint where the patient is lying semisupine on the examination bed. This is in contrast with the conventional positioning where the patient is sitting on the edge of the bed or across the table on a chair. Our proposed positioning is more comfortable for both the patient and ultrasound practitioner. It also allows immediate ultrasound-guided injections with lesser risk regarding a vasovagal syncope of the patient.
- Published
- 2018
27. Anodic Deposition of Enantiopure Hexahelicene Layers
- Author
-
Jan Vacek, Jan Hrbac, Jan Pokorný, Jan Sýkora, Jan Storch, Ladislav Fekete, Tomáš Strašák, Jiří Bulíř, Jeanne Crassous, Vladimír Církva, Magdaléna Hromadová, Palacky University Olomouc, Masaryk University [Brno] (MUNI), Czech Academy of Sciences [Prague] (CAS), Institut des Sciences Chimiques de Rennes (ISCR), Université de Rennes (UR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institutional Support of Palacky University in Olomouc, National Grid Infrastructure MetaCentrum [LM2010005], MEYS [LO1409, LD15058, LM2015088], FUNBIO [CZ.2.16/3.1.00/21568], Technology Agency of the Czech Republic [TA04010082], Czech Science Foundation [17-02578S, 15-12719S], Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université de Rennes 1 (UR1), Université de Rennes (UNIV-RENNES)-Université de Rennes (UNIV-RENNES)-Ecole Nationale Supérieure de Chimie de Rennes (ENSCR)-Institut National des Sciences Appliquées - Rennes (INSA Rennes), and Institut National des Sciences Appliquées (INSA)-Université de Rennes (UNIV-RENNES)-Institut National des Sciences Appliquées (INSA)
- Subjects
Circular dichroism ,Materials science ,010402 general chemistry ,Electrosynthesis ,Electrochemistry ,01 natural sciences ,Catalysis ,chemistry.chemical_compound ,symbols.namesake ,electrosynthesis ,redox chemistry ,Acetonitrile ,helicene ,electronic and spectral properties ,voltammetry ,010405 organic chemistry ,0104 chemical sciences ,Indium tin oxide ,Enantiopure drug ,chemistry ,Helicene ,symbols ,Physical chemistry ,[CHIM.OTHE]Chemical Sciences/Other ,Raman spectroscopy - Abstract
International audience; Helicenes are polyaromatic compounds with chiral properties useful for many applications in optoelectronics, separation processes, chiral recognition and catalysis. Here we focused on the electrochemistry of carbo[n]helicenes (n=5,6,7). The cyclic voltammograms of racemic mixtures of target compounds in acetonitrile/0.1M tetrabutylammonium perchlorate at a glassy carbon electrode reveal the diffusion-controlled reactions in both anodic and cathodic potential regions. Electrochemical behaviors are different for individual helicenes, [7]helicene undergoes redox transformation easily in comparison to the other investigated compounds, which is in agreement with DFT (density functional theory) calculations. Generally, the multi-component anodic process of helicenes is observable at potentials from +1.5 to +2.5V, leading to the formation of deposited structures (layers) on the electrode surface. The helicenes were electrodeposited onto transparent indium tin oxide (ITO) electrodes and characterized by atomic force microscopy, UV/Vis, Raman spectroscopy and ellipsometry. Finally, the anodic deposition of P and M enantiomers of [6]helicene was performed using ITO substrates, resulting in the formation of enantiopure layers of nanometer thicknesses, as confirmed by circular dichroism spectroscopy. The discovered electrosynthetic procedure opens up a new possibility for the immobilization of chiral helicene layers onto solid supports.
- Published
- 2018
28. Carbon fiber on-line detector for monitoring human blood serum reductive capacity. A complex technical solution
- Author
-
Jan Hrbac, David Novak, Marek Svarc, Petr Knopf, and Jan Vacek
- Subjects
0301 basic medicine ,Flow injection analysis ,Working electrode ,Chemistry ,General Chemical Engineering ,Analytical chemistry ,Ascorbic acid ,Redox ,Amperometry ,Analytical Chemistry ,Electrochemical cell ,03 medical and health sciences ,030104 developmental biology ,Blood serum ,Electrode ,Electrochemistry - Abstract
The construction of a cylindrical carbon fiber on-line detector is presented, featuring a novel way of sealing the carbon fiber microelectrode, the design of an interchangeable carbon fiber microelectrode-based flow cell and its interface with data-acquisition electronics. The two-electrode setup was used, where the regeneration of the carbon fiber working electrode surface between analyses was performed using an electrochemical procedure, typically −1/+1 V potential cycling. The detector was incorporated into the flow injection analysis manifold and the applicability of the developed sensing platform tested for monitoring a hexacyanoferrate (II/III) redox probe and the oxidizable compounds trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid), uric acid, and l -ascorbic acid, with dehydroascorbic acid as a negative control. Finally, the optimized procedure was utilized for the analysis of human blood serum reductive (antioxidant) capacity based on amperometric sensing and flow injection analysis at a flow rate of 10 μl/min. Amperometric responses for blood serum samples were evaluated for standard deviation, whose average value was estimated to be ±0.3 nA (n = 20). The electrolytic efficiency of the detector was on the order of % units, e.g. 2% for trolox. The flow cell geometry and application of carbon fiber electrodes resulted in the absence of dead volumes and passivation phenomena, in contrast to conventional high-surface-area electrochemical cells. We suppose that the complex technical solution presented here could find a broad range of applications in the on-line monitoring of other reducing low-molecular bioactives and of the redox properties of various body fluids or clinical samples.
- Published
- 2018
29. Electrochemical behavior of sarco/endoplasmic reticulum Ca-ATPase in response to carbonylation processes
- Author
-
Martina Zatloukalová, Magdalena Majekova, Silvia Michalikova, David Novak, Vladimir Heger, Jana Viskupicova, and Jan Vacek
- Subjects
SERCA ,Chemistry ,General Chemical Engineering ,Endoplasmic reticulum ,010401 analytical chemistry ,Methylglyoxal ,Skeletal muscle ,02 engineering and technology ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Analytical Chemistry ,Calcium ATPase ,Cytosol ,chemistry.chemical_compound ,Muscle relaxation ,medicine.anatomical_structure ,ATP hydrolysis ,Electrochemistry ,medicine ,Biophysics ,0210 nano-technology - Abstract
Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) is a transmembrane protein that transfers calcium ions from the cytosol of the cell to the lumen of the sarco/endoplasmic reticulum (SR) at the expense of ATP hydrolysis during muscle relaxation. Here we report the electrochemical monitoring of a SERCA1 isoform isolated from rabbit skeletal muscle. The constant-current chronopotentiometric stripping (CPS) analysis was applied for the analysis of solubilized SERCA1 based on a catalytic hydrogen evolution reaction (CHER). Consequently we applied an optimized CPS electrochemical protocol for monitoring the interaction of SERCA1 with the dicarbonyl compounds methylglyoxal, glyoxal and 3‑deoxyglucosone. We observed that SERCA1 readily interacts with methylglyoxal at pH 7.4. Electrochemical analysis showed that 1 mg/ml (9.1 μmol/l) SERCA1 was fully modified by methylglyoxal (3 mmol/l) after 24 h. The dicarbonyl binding decreased the enzyme activity of purified SERCA1 in the following order: methylglyoxal ≫ glyoxal > 3‑deoxyglucosone. The methodology presented here could be used in further studies of the structural integrity and intermolecular interactions of membrane transporters and the study of their oxidative modifications, carbonylation or glycoxidation.
- Published
- 2018
30. Lipidic liquid crystalline cubic phases for preparation of ATP-hydrolysing enzyme electrodes
- Author
-
David Novak, Jan Vacek, Ewa Nazaruk, Martina Zatloukalová, and Renata Bilewicz
- Subjects
Models, Molecular ,Swine ,ATPase ,Inorganic chemistry ,Biomedical Engineering ,Biophysics ,Enzyme electrode ,Biosensing Techniques ,02 engineering and technology ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,Ammonium phosphomolybdate ,Glycerides ,chemistry.chemical_compound ,Adenosine Triphosphate ,Animals ,Na+/K+-ATPase ,Voltammetry ,Enzyme Assays ,Ammonium molybdate ,biology ,Chemistry ,Hydrolysis ,General Medicine ,respiratory system ,Enzymes, Immobilized ,021001 nanoscience & nanotechnology ,Liquid Crystals ,0104 chemical sciences ,Membrane ,biology.protein ,Sodium-Potassium-Exchanging ATPase ,0210 nano-technology ,Biotechnology - Abstract
The lipidic liquid-crystalline cubic phase (LCP) is a membrane-mimetic material useful for the stabilization and structural analysis of membrane proteins. Here, we focused on the incorporation of the membrane ATP-hydrolysing sodium/potassium transporter Na + /K + -ATPase (NKA) into a monoolein-derived LCP. Small-angle X-ray scattering was employed for the determination of the LCP structure, which was of Pn3m symmetry for all the formulations studied. The fully characterized NKA-LCP material was immobilized onto a glassy carbon electrode, forming a highly stable enzyme electrode and a novel sensing platform. A typical NKA voltammetric signature was monitored via the anodic reaction of tyrosine and tryptophan residues. The in situ enzyme activity evaluation was based on the ability of NKA to transform ATP to ADP and free phosphate, the latter reacting with ammonium molybdate to form the ammonium phosphomolybdate complex under acidic conditions. The square-wave voltammetric detection of phosphomolybdate was performed and complemented with spectrophotometric measurement at 710 nm. The anodic voltammetric response, corresponding to the catalytic ATP-hydrolysing function of NKA incorporated into the LCP, was monitored at around + 0.2 V vs. Ag/AgCl in the presence or absence of ouabain, a specific NKA inhibitor. NKA incorporated into the LCP retained its ATP-hydrolysing activity for 7 days, while the solubilized protein became practically inactive. The novelty of this work is the first incorporation of NKA into a lipidic cubic phase with consequent enzyme functionality and stability evaluation using voltammetric detection. The application of LCPs could also be important in the further development of new membrane protein electrochemical sensors and enzyme electrodes.
- Published
- 2018
31. Nontoxic combretafuranone analogues with high in vitro antibacterial activity
- Author
-
P. Horký, Jiří Kuneš, David Sedlák, Petr Bartůněk, Milan Pour, M. Voráčová, Jan Vacek, and Klára Konečná
- Subjects
Antifungal Agents ,Cell Survival ,Stereochemistry ,Apoptosis ,Caspase 3 ,Microbial Sensitivity Tests ,01 natural sciences ,Structure-Activity Relationship ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Drug Discovery ,Humans ,Cytotoxic T cell ,Hydroxymethyl ,Furans ,Cytotoxicity ,IC50 ,Cells, Cultured ,Cell Proliferation ,Pharmacology ,Combretastatin ,Bacteria ,Dose-Response Relationship, Drug ,Molecular Structure ,010405 organic chemistry ,Organic Chemistry ,Fungi ,General Medicine ,In vitro ,Anti-Bacterial Agents ,0104 chemical sciences ,chemistry ,030220 oncology & carcinogenesis ,Antibacterial activity - Abstract
A library of thirty two 3,4-diphenylfuranones related to both combretastatin A-4 and antifungal 5-(acyloxymethyl)-3-(halophenyl)-2,5-dihydrofuran-2-ones was prepared. Cytotoxic effects on a panel of cancer and normal cell lines and antiinfective activity were evaluated, and the data were complemented with tests for the activation of caspase 3 and 7. High cytotoxicity was observed in some of the halogenated analogues, eg. 3-(3,4-dichlorophenyl)-4-(4-methylphenyl)-2,5-dihydrofuran-2-one with IC50 0.12–0.23 μM, but the compounds were also highly toxic against non-malignant control cells. More importantly, notable antibacterial activity indicating G+ selectivity has been found in the 3,4-diarylfuranone class of compounds for the first time. Hydroxymethylation of furanone C5 knocked out cytotoxic effects (up to 40 μM) while maintaining significant activity against Staphylococcus strains in some derivatives. MIC95 of the most promising compound, 3-(4-bromophenyl)-5,5-bis(hydroxymethyl)-4-(4-methylphenyl)-2,5-dihydrofuran-2-one against S. aureus strain ATCC 6538 was 0.98 μM (0.38 μg/mL) and 3.9 μM (1.52 μg/mL) after 24 and 48 h, respectively.
- Published
- 2018
32. Cover Feature: Flavin‐Helicene Amphiphilic Hybrids: Synthesis, Characterization, and Preparation of Surface‐Supported Films (ChemPlusChem 7/2021)
- Author
-
Jan Hrbac, Jaroslav Žádný, Martina Zatloukalová, Renata Bilewicz, Jeanne Crassous, Ivana Císařová, Martin Jakubec, Ludovic Favereau, Adrianna Cytryniak, Radek Cibulka, Jan Storch, David Novak, and Jan Vacek
- Subjects
chemistry.chemical_compound ,Helicene ,010405 organic chemistry ,Chemistry ,Amphiphile ,Cover (algebra) ,General Chemistry ,Flavin group ,010402 general chemistry ,01 natural sciences ,Combinatorial chemistry ,0104 chemical sciences ,Characterization (materials science) - Published
- 2021
33. Potential-Driven On/Off Switch Strategy for the Electrosynthesis of [7]Helicene-Derived Polymers
- Author
-
Ladislav Fekete, Jan Hrbac, Jan Pokorný, Tomáš Strašák, Jan Vacek, Jaroslav Žádný, Jan Storch, Milos Krbal, Jiří Bulíř, and Vít Ladányi
- Subjects
Organic electronics ,Materials science ,Inorganic chemistry ,02 engineering and technology ,Glassy carbon ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrosynthesis ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Indium tin oxide ,chemistry.chemical_compound ,Helicene ,chemistry ,Chemical engineering ,Electrochemistry ,Thiophene ,Cyclic voltammetry ,0210 nano-technology ,Acetonitrile - Abstract
New materials bearing thiophene and helicene moieties were prepared by a potential-driven on/off switch strategy onto the surface of glassy carbon and indium tin oxide substrates. Specifically, a 3-([7]helicen-9-yl)-thiophene hybrid monomer was electrooxidized in acetonitrile by cyclic voltammetry with anodic potential limits of +1.5 V or +2.5 V, resulting in a conductive and non-conductive polymer, respectively. The electrochemical findings were supplemented by microscopy investigations; UV-Vis, fluorescence and vibrational spectroscopies; 1H NMR spectroscopy; ellipsometry measurements and computational chemistry. The electrodeposited polymers could be used for the further development of materials applicable in organic electronics, optoelectronics and sensing technologies.
- Published
- 2017
34. Oxidation of Natural Bioactive Flavonolignan 2,3-Dehydrosilybin: An Electrochemical and Spectral Study
- Author
-
David Biedermann, Jan Vacek, Jana Kocábová, Petr Marhol, Romana Sokolová, Jan Fiedler, and Vladimír Křen
- Subjects
Spectrophotometry, Infrared ,Double bond ,Photochemistry ,Electrochemistry ,01 natural sciences ,Chemical reaction ,Electron Transport ,03 medical and health sciences ,chemistry.chemical_compound ,Electron transfer ,0302 clinical medicine ,Materials Chemistry ,Flavonolignan ,Molecule ,Organic chemistry ,Physical and Theoretical Chemistry ,Acetonitrile ,chemistry.chemical_classification ,010405 organic chemistry ,Electrochemical Techniques ,0104 chemical sciences ,Surfaces, Coatings and Films ,Flavonolignans ,chemistry ,Silybin ,030220 oncology & carcinogenesis ,Quantum Theory ,Spectrophotometry, Ultraviolet ,Derivative (chemistry) ,Silymarin - Abstract
The electrochemical oxidation of the natural antioxidant 2,3-dehydrosilybin (DHS) was investigated in acetonitrile. The spectral changes during two electron and two proton oxidation registered by in situ IR spectroelectrochemistry show that the electron transfer is followed by a subsequent chemical reaction with traces of water. A benzofuranone derivative (BF) is formed by ECEC (electron transfer-chemical reaction-electron transfer-chemical reaction) process at the potential of the first oxidation wave. A minor difference in the chemical structures of flavonolignans DHS and silybin, the presence of a double bond between atoms C-2 and C-3 in the DHS molecule, causes the formation of completely different oxidation products. BF was for the first time identified as the product of the oxidation of flavonolignan DHS. Its formation was proved by electroanalytical, chromatographic, and spectroelectrochemical techniques. Molecular orbital calculations support the experimental findings.
- Published
- 2017
35. Na+/K+-ATPase interaction with methylglyoxal as reactive metabolic side product
- Author
-
Petra Dvorakova, Jan Vacek, Marika Svrckova, Dominika Coufalová, David Novak, Lenka Hernychova, and Martina Zatloukalová
- Subjects
0301 basic medicine ,chemistry.chemical_classification ,biology ,Methylglyoxal ,Lysine ,02 engineering and technology ,respiratory system ,021001 nanoscience & nanotechnology ,Biochemistry ,Ouabain ,Pimagedine ,03 medical and health sciences ,chemistry.chemical_compound ,030104 developmental biology ,Enzyme ,chemistry ,Glycation ,Physiology (medical) ,medicine ,biology.protein ,Na+/K+-ATPase ,Bovine serum albumin ,0210 nano-technology ,medicine.drug - Abstract
Proteins are subject to oxidative modification and the formation of adducts with a broad spectrum of reactive species via enzymatic and non-enzymatic mechanisms. Here we report that in vitro non-enzymatic methylglyoxal (MGO) binding causes the inhibition and formation of MGO advanced glycation end-products (MAGEs) in Na+/K+-ATPase (NKA). Concretely, MGO adducts with NKA amino acid residues (mainly Arg) and Ne-(carboxymethyl)lysine (CML) formation were found. MGO is not only an inhibitor for solubilized NKA (IC50=91±16μM), but also for reconstituted NKA in the lipid bilayer environment, which was clearly demonstrated using a DPPC/DPPE liposome model in the presence or absence of the NKA-selective inhibitor ouabain. High-resolution mass spectrometric analysis of a tryptic digest of NKA isolated from pig (Sus scrofa) kidney indicates that the intracellular α-subunit is naturally (post-translationally) modified by MGO in vivo. In contrast to this, the β-subunit could only be modified by MGO artificially, and the transmembrane part of the protein did not undergo MGO binding under the experimental setup used. As with bovine serum albumin, serving as the water-soluble model, we also demonstrated a high binding capacity of MGO to water-poorly soluble NKA using a multi-spectral methodology based on electroanalytical, immunochemical and fluorimetric tools. In addition, a partial suppression of the MGO-mediated inhibitory effect could be observed in the presence of aminoguanidine (pimagedine), a glycation suppressor and MGO-scavenger. All the results here were obtained with the X-ray structure of NKA in the E1 conformation (3WGV) and could be used in the further interpretation of the functionality of this key enzyme in the presence of highly-reactive metabolic side-products, glycation agents and generally under oxidative stress conditions.
- Published
- 2017
36. Introduction to Neuromuscular Ultrasound
- Author
-
Jan Vacek, Petra Steyerova, Kamal Mezian, and Leoš Navrátil
- Subjects
business.industry ,Anesthesia ,0202 electrical engineering, electronic engineering, information engineering ,Medicine ,020201 artificial intelligence & image processing ,Surgery ,02 engineering and technology ,Neurology (clinical) ,021001 nanoscience & nanotechnology ,0210 nano-technology ,business ,Neuromuscular ultrasound - Published
- 2016
37. Cover Feature: Structures of Peptidic H‐wires at Mercury Surface: Molecular Dynamics Study (Electroanalysis 10/2019)
- Author
-
Vlastimil Dorčák, Ondřej Kroutil, Martin Kabeláč, and Jan Vacek
- Subjects
Molecular dynamics ,Materials science ,chemistry ,Chemical physics ,Electrochemistry ,chemistry.chemical_element ,Helical peptide ,Analytical Chemistry ,Mercury (element) - Published
- 2019
38. Redox properties of individual quercetin moieties
- Author
-
Marek Kuzma, Jan Vacek, Patrick Trouillas, Martina Bancířová, Michal Biler, Vladimír Křen, Martina Zatloukalová, Romana Sokolová, Andreas G. Tzakos, and Eva Heřmánková
- Subjects
0301 basic medicine ,Catechol ,Free Radical Scavengers ,Alkylation ,Biochemistry ,Combinatorial chemistry ,Enol ,Redox ,Antioxidants ,03 medical and health sciences ,chemistry.chemical_compound ,Electron transfer ,Structure-Activity Relationship ,030104 developmental biology ,0302 clinical medicine ,chemistry ,Physiology (medical) ,Taxifolin ,Moiety ,heterocyclic compounds ,Quercetin ,Oxidation-Reduction ,030217 neurology & neurosurgery - Abstract
Quercetin is one of the most prominent and widely studied flavonoids. Its oxidation has been previously investigated only indirectly by comparative analyses of structurally analogous compounds, e.g. dihydroquercetin (taxifolin). To provide direct evidence about the mechanism of quercetin oxidation, we employed selective alkylation procedures for the step-by-step blocking of individual redox active sites, i.e. the catechol, resorcinol and enol C-3 hydroxyls, as represented by newly prepared quercetin derivatives 1–3. Based on the structure-activity relationship (SAR), electrochemical, and computational (density functional theory) studies, we can clearly confirm that quercetin is oxidized in the following steps: the catechol moiety is oxidized first, forming the benzofuranone derivative via intramolecular rearrangement mechanism; therefore the quercetin C-3 hydroxy group cannot be involved in further oxidation reactions or other biochemical processes. The benzofuranone is oxidized subsequently, followed by oxidation of the resorcinol motif to complete the electrochemical cascade of reactions. Derivatization of individual quercetin hydroxyls has a significant effect on its redox behavior, and, importantly, on its antiradical and stability properties, as shown in DPPH/ABTS radical scavenging assays and UV–Vis spectrophotometry, respectively. The SAR data reported here are instrumental for future studies on the oxidation of biologically or technologically important flavonoids and other polyphenols or polyhydroxy substituted aromatics. This is the first complete and direct study mapping redox properties of individual moieties in quercetin structure.
- Published
- 2019
39. Cytotoxicity of hexahelicene and its effect on the aryl hydrocarbon receptor pathway
- Author
-
Jiri Vrba, Jan Storch, Jan Vacek, Lenka Roubalová, and Vladimír Církva
- Subjects
0301 basic medicine ,Toxicology ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Cytochrome P-450 CYP1A1 ,Cytotoxic T cell ,Humans ,Polycyclic Compounds ,Viability assay ,Cytotoxicity ,biology ,Activator (genetics) ,Imidazoles ,Cytochrome P450 ,General Medicine ,Transfection ,Hep G2 Cells ,respiratory system ,Aryl hydrocarbon receptor ,Molecular biology ,030104 developmental biology ,Helicene ,chemistry ,Receptors, Aryl Hydrocarbon ,030220 oncology & carcinogenesis ,biology.protein ,Signal Transduction - Abstract
Carbohelicenes are a group of helical-shaped polycyclic aromatic hydrocarbons. This study examined the effect of hexahelicene (or [6]helicene) and of its imidazolium derivative, 1-butyl-3-(2-methyl[6]helicenyl)-imidazolium bromide (I[6]H), on the activity of the aryl hydrocarbon receptor (AhR) and expression of cytochrome P450 1A1 (CYP1A1) in human hepatoma HepG2 cells. An MTT viability assay showed that both [6]helicene and I[6]H were cytotoxic to HepG2 cells after 24 h of exposure, with IC50 values of 0.9 and 8.4 μM, respectively. Using a gene reporter assay performed in transiently transfected HepG2 cells, we found that 1 μM [6]helicene, unlike I[6]H, significantly increased the activity of AhR to 2.1-fold compared to the control after 24 h of exposure. Moreover, [6]helicene induced a small but significant increase in the level of CYP1A1 mRNA. On the other hand, neither the protein level nor activity of CYP1A1 were affected by [6]helicene in HepG2 cells. The effect of [6]helicene on the AhR pathway was thus much lower than that of 2,3,7,8-tetrachlorodibenzo-p-dioxin, a potent AhR activator. We conclude that [6]helicene is a poor activator of the AhR pathway in HepG2 cells, and that the possible activation of the AhR pathway in vivo remains to be investigated.
- Published
- 2018
40. Flavonolignan Conjugates as DNA-binding Ligands and Topoisomerase I Inhibitors: Electrochemical and Electrophoretic Approaches
- Author
-
Vladimír Křen, Jan Coufal, Ana Dora Rodrigues Pontinha, Ana Maria Oliveira-Brett, Miroslav Fojta, Jan Vacek, Eva Vavříková, Jitka Ulrichová, and Martina Zatloukalová
- Subjects
010405 organic chemistry ,Chemistry ,Topoisomerase-I Inhibitor ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,0104 chemical sciences ,Analytical Chemistry ,chemistry.chemical_compound ,Electrophoresis ,Biochemistry ,Flavonolignan ,Nucleic acid ,DNA ,Conjugate - Published
- 2016
41. Oxidation of the Flavonolignan Silybin. In situ EPR Evidence of the Spin-Trapped Silybin Radical
- Author
-
Romana Sokolová, Ján Tarábek, Eva Vavříková, Vladimír Křen, Jana Kocábová, Barbora Papoušková, Jan Fiedler, Jan Vacek, and Petr Marhol
- Subjects
Spin trapping ,Chemistry ,General Chemical Engineering ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,Electrochemistry ,01 natural sciences ,Redox ,0104 chemical sciences ,law.invention ,Adduct ,chemistry.chemical_compound ,law ,Reagent ,Flavonolignan ,0210 nano-technology ,Electron paramagnetic resonance ,Derivative (chemistry) - Abstract
Oxidation of natural flavonolignan silybin in an aprotic environment was studied by electrochemical methods, electron paramagnetic resonance (EPR), UV–vis and IR in situ spectroelectrochemistry and chromatographic techniques. The presence of electrochemically generated silybin radical was proven using in situ EPR spectroelectrochemistry by spin trapping method with 5-tert-butoxycarbonyl-5-methyl-1-pyrroline-N-oxide (BMPO) as a spin trap reagent. The adduct of the silybin radical with BMPO was additionally unambiguously identified by UPLC-ESI-MS/MS. For the first time, the flavonolignan radical was detected upon electrochemical oxidation under such conditions. The one-electron oxidation of silybin leads to a hydroxylated silybin derivative. Its specific redox behaviour can reflect its bioefficiency.
- Published
- 2016
42. Electrocatalytic monitoring of peptidic proton-wires
- Author
-
Ondřej Kroutil, K. Bednářová, Vlastimil Dorčák, Martin Kabeláč, and Jan Vacek
- Subjects
Proton ,Chemistry ,Ab initio ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Biochemistry ,Acceptor ,0104 chemical sciences ,Analytical Chemistry ,Solvent ,Computational chemistry ,Transfer Ability ,Solvents ,Electrochemistry ,Environmental Chemistry ,Histidine ,Protons ,Peptides ,0210 nano-technology ,Spectroscopy ,Macromolecule - Abstract
The transfer of protons or proton donor/acceptor abilities is an important phenomenon in many biomolecular systems. One example is the recently proposed peptidic proton-wires (H-wires), but the ability of these His-containing peptides to transfer protons has only been studied at the theoretical level so far. Here, for the first time the proton transfer ability of peptidic H-wires is examined experimentally in an adsorbed state using an approach based on a label-free electrocatalytic reaction. The experimental findings are complemented by theoretical calculations at the ab initio level in a vacuum and in an implicit solvent. Experimental and theoretical results indicated Ala3(His-Ala2)6 to be a high proton-affinity peptidic H-wire model. The methodology presented here could be used for the further investigation of the proton-exchange chemistry of other biologically or technologically important macromolecules.
- Published
- 2016
43. Cover Feature: Chiral Electrochemistry: Anodic Deposition of Enantiopure Helical Molecules (ChemPlusChem 9/2020)
- Author
-
Jaroslav Zadny, Jan Hrbac, Jan Storch, and Jan Vacek
- Subjects
Materials science ,010405 organic chemistry ,General Chemistry ,010402 general chemistry ,Electrochemistry ,01 natural sciences ,0104 chemical sciences ,Anode ,Crystallography ,Enantiopure drug ,Molecule ,Cover (algebra) ,Chirality (chemistry) ,Deposition (chemistry) - Published
- 2020
44. Structural Stability of Peptidic His-Containing Proton Wire in Solution and in the Adsorbed State
- Author
-
Ondřej Kroutil, Lucie Bednárová, Jan Vacek, Martin Kabeláč, Vlastimil Dorčák, Vaclav Veverka, and David Novak
- Subjects
0301 basic medicine ,Materials science ,Magnetic Resonance Spectroscopy ,Stripping (chemistry) ,Proton ,Molecular Dynamics Simulation ,010402 general chemistry ,01 natural sciences ,Protein Structure, Secondary ,03 medical and health sciences ,Molecular dynamics ,Molecular wire ,Electrochemistry ,General Materials Science ,Histidine ,Electrodes ,Spectroscopy ,Aqueous solution ,Circular Dichroism ,Surfaces and Interfaces ,Nuclear magnetic resonance spectroscopy ,Electrochemical Techniques ,Trifluoroethanol ,Condensed Matter Physics ,0104 chemical sciences ,030104 developmental biology ,Electrode ,Solvents ,Physical chemistry ,Proton affinity ,Protons ,Peptides - Abstract
Molecular wires are functional molecules applicable in the field of transfer processes in technological and biochemical applications. Besides molecular wires with the ability to transfer electrons, research is currently focused on molecular wires with high proton affinity and proton transfer ability. Recently, proposed peptidic proton wires (H wires) are one example. Their ability to mediate the transport of protons from aqueous solutions onto the surface of a Hg electrode in a catalytic hydrogen evolution reaction was investigated by constant-current chronopotentiometric stripping. However, elucidating the structure of H wires and rationalizing their stability are key requirements for their further research and application. In this article, we focus on the His (H) and Ala (A)-containing peptidic H wire A3-(H-A2)6 in solution and after its immobilization onto the electrode surface in the presence of the secondary structure stabilizer 2,2,2-trifluoroethanol (TFE). We found that the solvent containing more ...
- Published
- 2018
45. Electrocatalytic artificial carbonylation assay for observation of human serum albumin inter-individual properties
- Author
-
Marika Svrckova, Jitka Ulrichová, Jitka Proskova, Martina Zatloukalová, Jan Vacek, David Novak, Katerina Langova, and Dana Galuszkova
- Subjects
0301 basic medicine ,Adult ,Male ,Biophysics ,Serum albumin ,Serum Albumin, Human ,02 engineering and technology ,Protein oxidation ,Biochemistry ,Protein Carbonylation ,03 medical and health sciences ,chemistry.chemical_compound ,Blood serum ,medicine ,Humans ,Molecular Biology ,biology ,Methylglyoxal ,Albumin ,Cell Biology ,Electrochemical Techniques ,021001 nanoscience & nanotechnology ,Human serum albumin ,body regions ,030104 developmental biology ,chemistry ,Nat ,embryonic structures ,biology.protein ,Female ,0210 nano-technology ,Ex vivo ,medicine.drug - Abstract
Human serum albumin (HSA) is a multifunctional protein with ligand binding, transporting and buffering properties. Posttranslational modifications and ligand binding processes are closely related to albumin final functional status. In the last few decades, HSA has been characterized using a broad spectrum of methods, but quantitative data on the HSA's modifications among individuals have not been reported. The investigations presented here are based on the non-denaturing electrocatalytic screening of HSA samples isolated from the blood serum of healthy subjects. The electrocatalytic responses of the native protein ( R nat ) varied depending on its modifications among individuals, which enable us to express the inter-individual variability. Consequently, the native HSA samples were subjected to ex vivo carbonylation with 50 mM methylglyoxal for 36 h. The differences between R nat and the responses of artificially carbonylated protein ( R mod ) corresponded with inter-individual binding capacity variations ( ΔR = R nat – R mod ). The coefficients of variation for the R nat and ΔR values of purified HSA samples were estimated to be 8.5 and 23.2%, respectively. A sensitive non-denaturing electrocatalytic assay was utilized to provide new data about albumin inter-individual variations and evaluate its oxidative modifications and binding capacity, which could be used for further studies targeting not only on HSA but also other clinically important proteins.
- Published
- 2018
46. Corrigendum to 'European contribution to the study of ROS: A summary of the findings and prospects for the future from the COST action BM1203 (EU-ROS)' [Redox Biol. 13 (2017) 94–162]
- Author
-
Alina Hanf, Alberto Bindoli, Miloš Mojović, David A. Bernlohr, Yuliya Mikhed, Paula M. Brito, Agnes Görlach, João G. Costa, Vladimír Křen, Rui M. Barbosa, Jose Viña, Khrystyna Semen, María Monsalve, Opeyemi S Ademowo, Andreas Petry, Jingjing Huang, Balaraman Kalyanaraman, Ioanna Andreadou, Javier Egea, Kateryna Kubaichuk, Antonio Martínez-Ruiz, Mutay Aslan, Helen R. Griffiths, Pietro Ghezzi, S. Ilikay, Rashid Giniatullin, Melanie Hillion, Shlomo Sasson, Verónica Miguel, John F. Mulvey, Huige Li, Nuno Saraiva, Kemal Sami Korkmaz, Brandán Pedre, Isabel T.N. Nguyen, Katrin Schröder, Maria Pia Rigobello, Holger Steinbrenner, João Laranjinha, Nikoletta Papaevgeniou, Péter Ferdinandy, Kateřina Valentová, Andrew R. Pitt, Nuno G. Oliveira, Amanda J. Edson, Gratiela Gradisteanu Pircalabioru, Paul G. Winyard, Matthias Oelze, Irundika H.K. Dias, Thomas Krieg, Joris Messens, Pidder Jansen-Dürr, Vaclav Hampl, Fernando Antunes, Yves Frapart, Thierry Soldati, Bilge Debelec-Butuner, Anabela P. Rolo, Tilman Grune, Jan Vacek, Thomas Münzel, Kahina Abbas, Marina Kleanthous, Anastasia Shakirzyanova, Neven Žarković, Belma Turan, Olga Vajnerova, F. Di Lisa, Irina Milisav, Thomas Kietzmann, Rhian M. Touyz, Lidija Milkovic, Antonio Cuadrado, Pierre-Alexis Mouthuy, Serge P. Bottari, Karl-Heinz Krause, Francis Rousset, Reiko Matsui, Catarina B. Afonso, Danylo Kaminskyy, Bebiana C. Sousa, F. Van Breusegem, Ana Sofia Fernandes, Antigone Lazou, Marcus Conrad, Isabel Fabregat, Bato Korac, Pablo Hernansanz-Agustín, Aleksandra Pavićević, Jaap A. Joles, Erkan Tuncay, Fabienne Peyrot, Anikó Görbe, Sebastian Steven, Harald H.H.W. Schmidt, Martina Zatloukalová, Jan Herget, Santiago Lamas, Kari E. Fladmark, Markus Bachschmid, Afroditi Chatzi, Geoffrey L. Smith, Fulvio Ursini, Joe Dan Dunn, Kostas Tokatlidis, Rafal Koziel, Andreas Papapetropoulos, Antonio Miranda-Vizuete, Jamel El-Benna, Vincent Jaquet, B. De Smet, Vladimir R. Muzykantov, Elizabeth A. Veal, Esther Bertran, Guia Carrara, Olha Yelisyeyeva, Haike Antelmann, Ana Stancic, A. S. Yalçin, M. El Assar, Ulla G. Knaus, Marcus S. Cooke, Vsevolod V. Belousov, Leocadio Rodríguez-Mañas, Lars-Oliver Klotz, Marios Phylactides, Manuela G. López, Marie José Stasia, Tatjana Ruskovska, Stuart P. Meredith, Lokman Varisli, Niki Chondrogianni, Mahsa Karbaschi, Rainer Schulz, Henrik E. Poulsen, Andreas Daiber, Natalia Robledinos-Antón, Corinne M. Spickett, Ulrich Förstermann, Višnja Stepanić, Tamara Seredenina, Carlos M. Palmeira, Gloria Olaso-Gonzalez, Ana I. Casas, Ignacio Prieto, Gethin J. McBean, Damir Kračun, P. My-Chan Dang, Jacek Zielonka, Zoltán Giricz, and Carsten Berndt
- Subjects
0301 basic medicine ,Societies, Scientific ,Redox signaling ,International Cooperation ,Clinical Biochemistry ,Nanotechnology ,Review Article ,Biology ,Public administration ,Biochemistry ,Antioxidants ,Article ,03 medical and health sciences ,media_common.cataloged_instance ,Animals ,Humans ,Cost action ,European Union ,European union ,Molecular Biology ,lcsh:QH301-705.5 ,media_common ,Funding Agency ,Redox therapeutics ,lcsh:R5-920 ,Organic Chemistry ,Reactive nitrogen species ,030104 developmental biology ,Work (electrical) ,lcsh:Biology (General) ,Oxidative stress ,Reactive Oxygen Species ,lcsh:Medicine (General) ,Oxidation-Reduction ,Signal Transduction - Abstract
The European Cooperation in Science and Technology (COST) provides an ideal framework to establish multi-disciplinary research networks. COST Action BM1203 (EU-ROS) represents a consortium of researchers from different disciplines who are dedicated to providing new insights and tools for better understanding redox biology and medicine and, in the long run, to finding new therapeutic strategies to target dysregulated redox processes in various diseases. This report highlights the major achievements of EU-ROS as well as research updates and new perspectives arising from its members. The EU-ROS consortium comprised more than 140 active members who worked together for four years on the topics briefly described below. The formation of reactive oxygen and nitrogen species (RONS) is an established hallmark of our aerobic environment and metabolism but RONS also act as messengers via redox regulation of essential cellular processes. The fact that many diseases have been found to be associated with oxidative stress established the theory of oxidative stress as a trigger of diseases that can be corrected by antioxidant therapy. However, while experimental studies support this thesis, clinical studies still generate controversial results, due to complex pathophysiology of oxidative stress in humans. For future improvement of antioxidant therapy and better understanding of redox-associated disease progression detailed knowledge on the sources and targets of RONS formation and discrimination of their detrimental or beneficial roles is required. In order to advance this important area of biology and medicine, highly synergistic approaches combining a variety of diverse and contrasting disciplines are needed., Graphical abstract fx1, Highlights • RONS are chemical mediators and a communication tool. • RONS and disturbed redox balance play a role in a broad range of diseases and aging. • Bacteria and toxins are important stimulators of cellular RONS formation. • Drugs should preserve beneficial redox signaling and inhibit detrimental RONS sources. • Redox drugs may target the origin, identity, location and time of RONS formation.
- Published
- 2018
- Full Text
- View/download PDF
47. Are High Proanthocyanidins Key to Cranberry Efficacy in the Prevention of Recurrent Urinary Tract Infection?
- Author
-
Ales Vidlar, Vladimír Študent, Vilím Šimánek, Benno F. Zimmermann, Pavel Kosina, Jitka Ulrichová, Jitka Vostálová, Jan Vacek, Adéla Galandáková, and Jana Vrbkova
- Subjects
Pharmacology ,medicine.medical_specialty ,business.industry ,Urinary system ,Significant difference ,bacterial infections and mycoses ,urologic and male genital diseases ,Placebo group ,female genital diseases and pregnancy complications ,RECURRENT UTI ,American cranberry ,food.food ,Surgery ,food ,Proanthocyanidin ,Internal medicine ,medicine ,Young adult ,business ,Survival analysis - Abstract
Most research on American cranberry in the prevention of urinary tract infection (UTI) has used juices. The spectrum of components in juice is limited. This study tested whether whole cranberry fruit powder (proanthocyanidin content 0.56%) could prevent recurrent UTI in 182 women with two or more UTI episodes in the last year. Participants were randomized to a cranberry (n = 89) or a placebo group (n = 93) and received daily 500 mg of cranberry for 6 months. The number of UTI diagnoses was counted. The intent-to-treat analyses showed that in the cranberry group, the UTIs were significantly fewer [10.8% vs. 25.8%, p = 0.04, with an age-standardized 12-month UTI history (p = 0.01)]. The Kaplan-Meier survival curves showed that the cranberry group experienced a longer time to first UTI than the placebo group (p = 0.04). Biochemical parameters were normal, and there was no significant difference in urinary phenolics between the groups at baseline or on day180. The results show that cranberry fruit powder (peel, seeds, pulp) may reduce the risk of symptomatic UTI in women with a history of recurrent UTIs.
- Published
- 2015
48. Metabolism of palmatine by human hepatocytes and recombinant cytochromes P450
- Author
-
Jitka Ulrichová, Martina Zatloukalová, Jiri Vrba, Michaela Pyszková, Barbora Papoušková, Karel Lemr, and Jan Vacek
- Subjects
Adult ,Male ,Spectrometry, Mass, Electrospray Ionization ,Adolescent ,Berberine Alkaloids ,Clinical Biochemistry ,Glucuronidation ,Pharmaceutical Science ,Analytical Chemistry ,Hydroxylation ,chemistry.chemical_compound ,Sulfation ,Cytochrome P-450 Enzyme System ,Biotransformation ,Tandem Mass Spectrometry ,Drug Discovery ,Humans ,Spectroscopy ,Demethylation ,Chromatography ,biology ,CYP1A2 ,Cytochrome P450 ,Palmatine ,Middle Aged ,Recombinant Proteins ,chemistry ,Biochemistry ,Hepatocytes ,biology.protein ,Female - Abstract
In this study, we developed a new liquid chromatography-mass spectrometry (LC-MS) method for analysis of the protoberberine alkaloid palmatine and its metabolites with separation performed on a cyanopropyl-modified stationary phase. Palmatine (10 μM) was metabolized using suspensions of human hepatocytes and human recombinant cytochrome P450 (CYP) enzymes. Our analyses using electrospray ionization-quadrupole time-of-flight mass spectrometry revealed that palmatine was relatively resistant to the metabolic activity of human hepatocytes and recombinant CYP enzymes. However, we found that the biotransformation of palmatine in human hepatocytes included O-demethylation or hydroxylation, and that the product of palmatine demethylation was conjugated by glucuronidation or sulfation. Moreover, we found that human recombinant CYP2D6 and, to a lesser extent, CYP1A2 can mediate O-demethylation of palmatine. These results provide fundamental insights into the biotransformation of palmatine in human in vitro models and, together with the LC-MS method, can be applied for further studies on the biotransformation of palmatine and other protoberberine alkaloids.
- Published
- 2015
49. Electrochemistry and electron paramagnetic resonance spectroscopy of cytochrome c and its heme-disrupted analogs
- Author
-
Jan Vacek, Martin Bartošík, Lenka Hernychova, Aleksandra Pavićević, Martina Zatloukalová, Miloš Mojović, and David Novak
- Subjects
Models, Molecular ,Hemeprotein ,Stereochemistry ,Protein Conformation ,Biophysics ,02 engineering and technology ,Heme ,010402 general chemistry ,Photochemistry ,01 natural sciences ,law.invention ,chemistry.chemical_compound ,law ,Electrochemistry ,Moiety ,Animals ,Hemeproteins ,Horses ,Physical and Theoretical Chemistry ,Electron paramagnetic resonance ,biology ,Cytochrome c peroxidase ,Cytochrome c ,Electron Spin Resonance Spectroscopy ,Cytochromes c ,General Medicine ,021001 nanoscience & nanotechnology ,Porphyrin ,0104 chemical sciences ,chemistry ,biology.protein ,Cattle ,0210 nano-technology - Abstract
Cytochrome c (cyt c) is one of the most studied conjugated proteins due to its electron-transfer properties and ability to regulate the processes involved in homeostasis or apoptosis. Here we report an electrochemical strategy for investigating the electroactivity of cyt c and its analogs with a disrupted heme moiety, i.e. apocytochrome c (acyt c) and porphyrin cytochrome c (pcyt c). The electrochemical data are supplemented with low-temperature and spin-probe electron paramagnetic resonance (EPR) spectroscopy. The main contribution of this report is a complex evaluation of cyt c reduction and oxidation at the level of surface-localized amino acid residues and the heme moiety in a single electrochemical scan. The electrochemical pattern of cyt c is substantially different to both analogs acyt c and pcyt c, which could be applicable in further studies on the redox properties and structural stability of cytochromes and other hemeproteins.
- Published
- 2017
50. Bilateral Rectus Femoris Muscle Rupture Following Statin Medication
- Author
-
Kamal Mezian, Levent Özçakar, Leoš Navrátil, and Jan Vacek
- Subjects
Male ,medicine.medical_specialty ,Statin ,Rupture, Spontaneous ,medicine.drug_class ,business.industry ,Rehabilitation ,MEDLINE ,Physical Therapy, Sports Therapy and Rehabilitation ,Rectus femoris muscle ,030204 cardiovascular system & hematology ,Surgery ,Quadriceps Muscle ,03 medical and health sciences ,0302 clinical medicine ,Muscular Diseases ,medicine ,Humans ,Hydroxymethylglutaryl-CoA Reductase Inhibitors ,business ,030217 neurology & neurosurgery ,Aged - Published
- 2017
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.