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Kircheva N, Petkova V, Dobrev S, Nikolova V, Angelova S, Dudev T. N-Methyl- and N-Phenylpiperazine Functionalized Styryl Dyes Inside Cucurbiturils: Theoretical Assessment of the Factors Governing the Host-Guest Recognition. Molecules 2023; 28:8130. [PMID: 38138619 PMCID: PMC10746092 DOI: 10.3390/molecules28248130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Revised: 12/04/2023] [Accepted: 12/14/2023] [Indexed: 12/24/2023] Open
Abstract
The family of cucurbiturils (CBs), the unique pumpkin-shaped macrocycles, has received great attention over the past four decades owing to their remarkable recognition properties. They have found diverse applications including biosensing and drug delivery technologies. The cucurbituril complexation of guest molecules can modulate their pKas, improve their solubility in aqueous solution, and reduce the adverse effects of the drugs, as well as enhance the stability and/or enable targeted delivery of the drug molecule. Employing twelve cationic styryl dyes with N-methyl- and N-phenylpiperazine functionality as probes, we attempted to understand the factors that govern the host-guest complexation of such molecules within CB[7] and CB[8] host systems. Various key factors determining the process were recognized, such as the pH and dielectric constant of the medium, the cavity size of the host, the chemical characteristics of the substituents in the guest entity, and the presence/absence of metal cations. The presented results add to our understanding (at the molecular level) of the mechanism of encapsulation of styryl dyes by cucurbiturils, thus shedding new light on various aspects of the intriguing complexation chemistry and the underlying recognition processes.
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Affiliation(s)
- Nikoleta Kircheva
- Institute of Optical Materials and Technologies “Acad. J. Malinowski”, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria; (N.K.); (V.P.); (S.D.); (S.A.)
| | - Vladislava Petkova
- Institute of Optical Materials and Technologies “Acad. J. Malinowski”, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria; (N.K.); (V.P.); (S.D.); (S.A.)
| | - Stefan Dobrev
- Institute of Optical Materials and Technologies “Acad. J. Malinowski”, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria; (N.K.); (V.P.); (S.D.); (S.A.)
| | - Valya Nikolova
- Faculty of Chemistry and Pharmacy, Sofia University “St. Kliment Ohridski”, 1164 Sofia, Bulgaria;
| | - Silvia Angelova
- Institute of Optical Materials and Technologies “Acad. J. Malinowski”, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria; (N.K.); (V.P.); (S.D.); (S.A.)
- University of Chemical Technology and Metallurgy, 8 St. Kliment Ohridski Blvd, 1756 Sofia, Bulgaria
| | - Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University “St. Kliment Ohridski”, 1164 Sofia, Bulgaria;
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2
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Angelova S, Kircheva N, Nikolova V, Dobrev S, Dudev T. Electrostatic interactions - key determinants of the metal selectivity in La 3+ and Ca 2+ binding proteins. Phys Chem Chem Phys 2023. [PMID: 37386862 DOI: 10.1039/d3cp01978k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/01/2023]
Abstract
Nearly half of all known proteins contain metal co-factors. In the course of evolution two dozen metal cations (mostly monovalent and divalent species) have been selected to participate in processes of vital importance for living organisms. Trivalent metal cations have also been selected, although to a lesser extent as compared with their mono- and divalent counterparts. Notably, factors governing the metal selectivity in trivalent metal centers in proteins are less well understood than those in the respective divalent metal centers. Thus, the source of high La3+/Ca2+ selectivity in lanthanum-binding proteins, as compared with that of calcium-binding proteins (i.e., calmodulin), is still shrouded in mystery. The well-calibrated thermochemical calculations, performed here, reveal the dominating role of electrostatic interactions in shaping the metal selectivity in La3+-binding centers. The calculations also disclose other (second-order) determinants of metal selectivity in these systems, such as the rigidity and extent of solvent exposure of the binding site. All these factors are also implicated in shaping the metal selectivity in Ca2+-binding proteins.
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Affiliation(s)
- Silvia Angelova
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
| | - Nikoleta Kircheva
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
| | - Valya Nikolova
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kliment Ohridski", 1164 Sofia, Bulgaria.
| | - Stefan Dobrev
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
| | - Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kliment Ohridski", 1164 Sofia, Bulgaria.
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3
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Kircheva N, Angelova S, Dobrev S, Petkova V, Nikolova V, Dudev T. Cu +/Ag + Competition in Type I Copper Proteins (T1Cu). Biomolecules 2023; 13:biom13040681. [PMID: 37189429 DOI: 10.3390/biom13040681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 04/13/2023] [Accepted: 04/14/2023] [Indexed: 05/17/2023] Open
Abstract
Due to the similarity in the basic coordination behavior of their mono-charged cations, silver biochemistry is known to be linked to that of copper in biological systems. Still, Cu+/2+ is an essential micronutrient in many organisms, while no known biological process requires silver. In human cells, copper regulation and trafficking is strictly controlled by complex systems including many cytosolic copper chaperones, whereas some bacteria exploit the so-called "blue copper" proteins. Therefore, evaluating the controlling factors of the competition between these two metal cations is of enormous interest. By employing the tools of computational chemistry, we aim to delineate the extent to which Ag+ might be able to compete with the endogenous copper in its Type I (T1Cu) proteins, and where and if, alternatively, it is handled uniquely. The effect of the surrounding media (dielectric constant) and the type, number, and composition of amino acid residues are taken into account when modelling the reactions in the present study. The obtained results clearly indicate the susceptibility of the T1Cu proteins to a silver attack due to the favorable composition and geometry of the metal-binding centers, along with the similarity between the Ag+/Cu+-containing structures. Furthermore, by exploring intriguing questions of both metals' coordination chemistry, an important background for understanding the metabolism and biotransformation of silver in organisms is provided.
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Affiliation(s)
- Nikoleta Kircheva
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Silvia Angelova
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Stefan Dobrev
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Vladislava Petkova
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Valya Nikolova
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kliment Ohridski", 1164 Sofia, Bulgaria
| | - Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kliment Ohridski", 1164 Sofia, Bulgaria
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Nikolova V, Kircheva N, Dobrev S, Angelova S, Dudev T. Lanthanides as Calcium Mimetic Species in Calcium-Signaling/Buffering Proteins: The Effect of Lanthanide Type on the Ca2+/Ln3+ Competition. Int J Mol Sci 2023; 24:ijms24076297. [PMID: 37047269 PMCID: PMC10094714 DOI: 10.3390/ijms24076297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 03/22/2023] [Accepted: 03/24/2023] [Indexed: 03/30/2023] Open
Abstract
Lanthanides, the 14 4f-block elements plus Lanthanum, have been extensively used to study the structure and biochemical properties of metalloproteins. The characteristics of lanthanides within the lanthanide series are similar, but not identical. The present research offers a systematic investigation of the ability of the entire Ln3+ series to substitute for Ca2+ in biological systems. A well-calibrated DFT/PCM protocol is employed in studying the factors that control the metal selectivity in biological systems by modeling typical calcium signaling/buffering binding sites and elucidating the thermodynamic outcome of the competition between the “alien” La3+/Ln3+ and “native” Ca2+, and La3+ − Ln3+ within the lanthanide series. The calculations performed reveal that the major determinant of the Ca2+/Ln3+ selectivity in calcium proteins is the net charge of the calcium binding pocket; the more negative the charge, the higher the competitiveness of the trivalent Ln3+ with respect to its Ca2+ contender. Solvent exposure of the binding site also influences the process; buried active centers with net charge of −4 or −3 are characterized by higher Ln3+ over Ca2+ selectivity, whereas it is the opposite for sites with overall charge of −1. Within the series, the competition between La3+ and its fellow lanthanides is determined by the balance between two competing effects: electronic (favoring heavier lanthanides) and solvation (generally favoring the lighter lanthanides).
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Affiliation(s)
- Valya Nikolova
- Faculty of Chemistry and Pharmacy, Sofia University “St. Kliment Ohridski”, 1164 Sofia, Bulgaria
| | - Nikoleta Kircheva
- Institute of Optical Materials and Technologies “Acad. J. Malinowski”, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Stefan Dobrev
- Institute of Optical Materials and Technologies “Acad. J. Malinowski”, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Silvia Angelova
- Institute of Optical Materials and Technologies “Acad. J. Malinowski”, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University “St. Kliment Ohridski”, 1164 Sofia, Bulgaria
- Correspondence:
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Nikolova V, Dobrev S, Kircheva N, Yordanova V, Dudev T, Angelova S. Host-guest complexation of cucurbit[7]uril and cucurbit[8]uril with the antimuscarinic drugs tropicamide and atropine. J Mol Graph Model 2023; 119:108380. [PMID: 36455472 DOI: 10.1016/j.jmgm.2022.108380] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 10/30/2022] [Accepted: 11/21/2022] [Indexed: 11/23/2022]
Abstract
Cucurbiturils are useful excipients in eye drop formulations: they can increase the water solubility of the drug, enhance drug absorption into the eye, improve aqueous stability and reduce local irritation. Effective and safe drug delivery is, however, a challenge and the information on the host (CBs)/guest (tropicamide and atropine) interactions can help improving the existing treatments and develop novel therapies not limited only to eye diseases/conditions. Since this carrier system can easily modify the properties of the drug and ensure its delivery at the targeted ocular tissue, further insight into the intimate mechanism of the host-guest recognition is crucial. The present DFT/SMD study focuses on the role of numerous factors governing this process, namely the specific position of the guest molecule in the cavity of the cucurbituril, the ionization form (non/protonated) of the antimuscarinic drug, the dielectric constant of the medium, and the size of the cavitant pore. The obtained results are in line with experimental observations and shed light on the mechanism, at atomic resolution, of recognition between the CBs and the two parasympatholytic drugs.
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Affiliation(s)
- Valya Nikolova
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kliment Ohridski", 1164, Sofia, Bulgaria
| | - Stefan Dobrev
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria
| | - Nikoleta Kircheva
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria
| | - Victoria Yordanova
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kliment Ohridski", 1164, Sofia, Bulgaria
| | - Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kliment Ohridski", 1164, Sofia, Bulgaria.
| | - Silvia Angelova
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences, 1113, Sofia, Bulgaria.
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6
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Kircheva N, Dobrev S, Nikolova V, Angelova S, Dudev T. Theoretical Insight into the Phosphate-Targeted Silver's Antibacterial Action: Differentiation between Gram (+) and Gram (-) Bacteria. Inorg Chem 2022; 61:10089-10100. [PMID: 35724666 DOI: 10.1021/acs.inorgchem.2c01085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Although silver is one of the first metals finding broad applications in everyday life, specific key points of the intimate mechanism of its bacteriostatic/bactericidal activity lack explanation. It is widely accepted that the antimicrobial potential of the silver cation depends on the composition and thickness of the bacterial external envelope: the outer membrane in Gram-negative bacteria is more prone to Ag+ attack than the cell wall in Gram-positive bacteria. The major cellular components able to interact strongly with Ag+ (teichoic acids, phospholipids, and lipopolysaccharides) contain mono/diesterified phosphate moieties. By applying a reliable DFT/SMD methodology, we modeled the reactions between the aforementioned constituents in typical Gram-positive and Gram-negative bacteria and hydrated Ag+ species, thus disclosing the factors that govern the process of metal-model ligand complexation. The conducted research indicates thermodynamically possible reactions in all cases but still a greater preference of the Ag+ toward the constituents in Gram-negative bacteria in comparison with their counterparts in Gram-positive bacteria. The observed tendencies shed light on the specific interactions of the silver cation with the modeled phosphate-containing units at the atomic level.
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Affiliation(s)
- Nikoleta Kircheva
- Institute of Optical Materials and Technologies ″Acad. J. Malinowski″, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Stefan Dobrev
- Institute of Optical Materials and Technologies ″Acad. J. Malinowski″, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Valya Nikolova
- Faculty of Chemistry and Pharmacy, Sofia University ″St. Kl. Ohridski″, 1164 Sofia, Bulgaria
| | - Silvia Angelova
- Institute of Optical Materials and Technologies ″Acad. J. Malinowski″, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University ″St. Kl. Ohridski″, 1164 Sofia, Bulgaria
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7
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Galabov B, Ilieva S, Cheshmedzhieva D, Nikolova V, Popov VA, Hadjieva B, Schaefer HF. Mini-Review on Structure-Reactivity Relationship for Aromatic Molecules: Recent Advances. ACS Omega 2022; 7:8199-8208. [PMID: 35309413 PMCID: PMC8928515 DOI: 10.1021/acsomega.1c07176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 02/22/2022] [Indexed: 06/14/2023]
Abstract
Recent advances in quantifying nucleophilic reactivities in chemical reactions and intermolecular interactions of aromatic molecules are reviewed. This survey covers experimental (IR frequency shifts induced by hydrogen bonding) and theoretical (modeling of potential energy surfaces, atomic charges, molecular electrostatic potential) approaches in characterizing chemical reactivity. Recent advances in software developments assisting the evaluation of the reactive sites for electrophilic aromatic substitution are briefly discussed.
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Affiliation(s)
- Boris Galabov
- Department
of Chemistry and Pharmacy, University of
Sofia, Sofia 1164, Bulgaria
| | - Sonia Ilieva
- Department
of Chemistry and Pharmacy, University of
Sofia, Sofia 1164, Bulgaria
| | | | - Valya Nikolova
- Department
of Chemistry and Pharmacy, University of
Sofia, Sofia 1164, Bulgaria
| | - Vassil A. Popov
- Department
of Chemistry and Pharmacy, University of
Sofia, Sofia 1164, Bulgaria
| | - Boriana Hadjieva
- Department
of Chemistry and Pharmacy, University of
Sofia, Sofia 1164, Bulgaria
| | - Henry F. Schaefer
- Center
for Computational Quantum Chemistry, University
of Georgia, Athens, Georgia 30602, United States
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Koleva IZ, Dobrev S, Kircheva N, Dasheva L, Nikolova V, Angelova S, Dudev T. Complexation of trivalent metal cations (Al 3+, Ga 3+, In 3+, La 3+, Lu 3+) to cucurbiturils: a DFT/SMD evaluation of the key factors governing the host-guest recognition. Phys Chem Chem Phys 2022; 24:6274-6281. [PMID: 35230371 DOI: 10.1039/d1cp04585g] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cucurbiturils (CBs), the pumpkin-shaped macrocycles, are suitable hosts for an array of neutral and cationic species. A plethora of host-guest complexes between CBs and a variety of guest molecules has been studied. However, much remains unknown, even in the complexation of very simple guests such as metal cations. In the computational study herein, DFT molecular modeling has been employed to investigate the interactions of a series of trivalent metal cations (Al3+, Ga3+, In3+, La3+, Lu3+) to cucurbit[n]urils and to evaluate the main factors controlling the host-guest complexation. The thermodynamic descriptors (Gibbs energies in the gas phase and in a water environment) of the corresponding complexation reactions have been estimated. This research is a logical continuation of an earlier study on the interaction between CB[n]s and a series of biologically essential mono- and divalent metal cations (Na+/K+ and Mg2+/Ca2+, respectively).
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Affiliation(s)
- Iskra Z Koleva
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski", 1164 Sofia, Bulgaria.
| | - Stefan Dobrev
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
| | - Nikoleta Kircheva
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
| | - Lyubima Dasheva
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski", 1164 Sofia, Bulgaria.
| | - Valya Nikolova
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski", 1164 Sofia, Bulgaria.
| | - Silvia Angelova
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
| | - Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski", 1164 Sofia, Bulgaria.
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Vologzhannikova AA, Shevelyova MP, Kazakov AS, Sokolov AS, Borisova NI, Permyakov EA, Kircheva N, Nikolova V, Dudev T, Permyakov SE. Strontium Binding to α-Parvalbumin, a Canonical Calcium-Binding Protein of the "EF-Hand" Family. Biomolecules 2021; 11:biom11081158. [PMID: 34439824 PMCID: PMC8392015 DOI: 10.3390/biom11081158] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 07/30/2021] [Accepted: 07/31/2021] [Indexed: 02/07/2023] Open
Abstract
Strontium salts are used for treatment of osteoporosis and bone cancer, but their impact on calcium-mediated physiological processes remains obscure. To explore Sr2+ interference with Ca2+ binding to proteins of the EF-hand family, we studied Sr2+/Ca2+ interaction with a canonical EF-hand protein, α-parvalbumin (α-PA). Evaluation of the equilibrium metal association constants for the active Ca2+ binding sites of recombinant human α-PA (‘CD’ and ‘EF’ sites) from fluorimetric titration experiments and isothermal titration calorimetry data gave 4 × 109 M−1 and 4 × 109 M−1 for Ca2+, and 2 × 107 M−1 and 2 × 106 M−1 for Sr2+. Inactivation of the EF site by homologous substitution of the Ca2+-coordinating Glu in position 12 of the EF-loop by Gln decreased Ca2+/Sr2+ affinity of the protein by an order of magnitude, whereas the analogous inactivation of the CD site induced much deeper suppression of the Ca2+/Sr2+ affinity. These results suggest that Sr2+ and Ca2+ bind to CD/EF sites of α-PA and the Ca2+/Sr2+ binding are sequential processes with the CD site being occupied first. Spectrofluorimetric Sr2+ titration of the Ca2+-loaded α-PA revealed presence of secondary Sr2+ binding site(s) with an apparent equilibrium association constant of 4 × 105 M−1. Fourier-transform infrared spectroscopy data evidence that Ca2+/Sr2+-loaded forms of α-PA exhibit similar states of their COO− groups. Near-UV circular dichroism (CD) data show that Ca2+/Sr2+ binding to α-PA induce similar changes in symmetry of microenvironment of its Phe residues. Far-UV CD experiments reveal that Ca2+/Sr2+ binding are accompanied by nearly identical changes in secondary structure of α-PA. Meanwhile, scanning calorimetry measurements show markedly lower Sr2+-induced increase in stability of tertiary structure of α-PA, compared to the Ca2+-induced effect. Theoretical modeling using Density Functional Theory computations with Polarizable Continuum Model calculations confirms that Ca2+-binding sites of α-PA are well protected against exchange of Ca2+ for Sr2+ regardless of coordination number of Sr2+, solvent exposure or rigidity of sites. The latter appears to be a key determinant of the Ca2+/Sr2+ selectivity. Overall, despite lowered affinity of α-PA to Sr2+, the latter competes with Ca2+ for the same EF-hands and induces similar structural rearrangements. The presence of a secondary Sr2+ binding site(s) could be a factor contributing to Sr2+ impact on the functional activity of proteins.
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Affiliation(s)
- Alisa A. Vologzhannikova
- Institute for Biological Instrumentation, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Pushchino, 142290 Moscow, Russia; (A.A.V.); (M.P.S.); (A.S.K.); (A.S.S.); (N.I.B.); (E.A.P.)
| | - Marina P. Shevelyova
- Institute for Biological Instrumentation, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Pushchino, 142290 Moscow, Russia; (A.A.V.); (M.P.S.); (A.S.K.); (A.S.S.); (N.I.B.); (E.A.P.)
| | - Alexey S. Kazakov
- Institute for Biological Instrumentation, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Pushchino, 142290 Moscow, Russia; (A.A.V.); (M.P.S.); (A.S.K.); (A.S.S.); (N.I.B.); (E.A.P.)
| | - Andrey S. Sokolov
- Institute for Biological Instrumentation, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Pushchino, 142290 Moscow, Russia; (A.A.V.); (M.P.S.); (A.S.K.); (A.S.S.); (N.I.B.); (E.A.P.)
| | - Nadezhda I. Borisova
- Institute for Biological Instrumentation, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Pushchino, 142290 Moscow, Russia; (A.A.V.); (M.P.S.); (A.S.K.); (A.S.S.); (N.I.B.); (E.A.P.)
| | - Eugene A. Permyakov
- Institute for Biological Instrumentation, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Pushchino, 142290 Moscow, Russia; (A.A.V.); (M.P.S.); (A.S.K.); (A.S.S.); (N.I.B.); (E.A.P.)
| | - Nikoleta Kircheva
- Institute of Optical Materials and Technologies “Acad. J. Malinowski”, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria;
| | - Valya Nikolova
- Faculty of Chemistry and Pharmacy, Sofia University “St. Kl. Ohridski”, 1164 Sofia, Bulgaria; (V.N.); (T.D.)
| | - Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University “St. Kl. Ohridski”, 1164 Sofia, Bulgaria; (V.N.); (T.D.)
| | - Sergei E. Permyakov
- Institute for Biological Instrumentation, Pushchino Scientific Center for Biological Research of the Russian Academy of Sciences, Pushchino, 142290 Moscow, Russia; (A.A.V.); (M.P.S.); (A.S.K.); (A.S.S.); (N.I.B.); (E.A.P.)
- Correspondence: ; Tel.: +7-(4967)-143-7741
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Damyanov D, Nikolova V, Angelova S, Dudev T. Halide anion solvation and recognition by bambusurils: A DFT study. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.116160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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11
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Nikolova V, Velinova A, Dobrev S, Kircheva N, Angelova S, Dudev T. Host-Guest Complexation of Cucurbit[7]Uril and Cucurbit[8]Uril with the Antineoplastic and Multiple Sclerosis Agent Mitoxantrone (Novantrone). J Phys Chem A 2021; 125:536-542. [PMID: 33415972 DOI: 10.1021/acs.jpca.0c08544] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The nature of interactions between the neutral/protonated mitoxantrone and the cucurbit[n]uril (n = 7, 8) host system was analyzed by employing density functional theory calculations. A comparison between the inclusion complexes of CB[7] and CB[8] shows various subtle differences in the complexation thermodynamics, given as changes in the Gibbs energy. Doubly and quadruply charged mitoxantrone (MX) molecules spontaneously form complexes in a water solvent, which are modeled using the polarizable continuum model approach. Both CB[7] and CB[8] complexes are stable as the geometry of the cavity allows for electrostatic interactions between the charged MX arms and the rim of the CB cavity. CB[8] also forms a stable complex with two mitoxantrone molecules with their aromatic rings stacked inside the cavity. Both CB[7] and CB[8] show properties that can be utilized in drug delivery.
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Affiliation(s)
- Valya Nikolova
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski", 1164 Sofia, Bulgaria
| | - Anita Velinova
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski", 1164 Sofia, Bulgaria
| | - Stefan Dobrev
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Nikoleta Kircheva
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Silvia Angelova
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski", 1164 Sofia, Bulgaria
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Kircheva N, Dobrev S, Nikolova V, Angelova S, Dudev T. Zinc and Its Critical Role in Retinitis pigmentosa: Insights from DFT/SMD Calculations. Inorg Chem 2020; 59:17347-17355. [DOI: 10.1021/acs.inorgchem.0c02664] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Nikoleta Kircheva
- Institute of Optical Materials and Technologies “Acad. J. Malinowski”, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Stefan Dobrev
- Institute of Optical Materials and Technologies “Acad. J. Malinowski”, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Valya Nikolova
- Faculty of Chemistry and Pharmacy, Sofia University “St. Kl. Ohridski”, 1164 Sofia, Bulgaria
| | - Silvia Angelova
- Institute of Optical Materials and Technologies “Acad. J. Malinowski”, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University “St. Kl. Ohridski”, 1164 Sofia, Bulgaria
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Kircheva N, Dobrev S, Dasheva L, Koleva I, Nikolova V, Angelova S, Dudev T. Complexation of biologically essential (mono- and divalent) metal cations to cucurbiturils: a DFT/SMD evaluation of the key factors governing the host-guest recognition. RSC Adv 2020; 10:28139-28147. [PMID: 35519129 PMCID: PMC9055741 DOI: 10.1039/d0ra04387g] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 07/20/2020] [Indexed: 01/31/2023] Open
Abstract
Supramolecular complexes based on classical synthetic macrocyclic host molecules such as cyclodextrins and calixarenes have received much attention recently due to their broad applications as biological and chemical sensors, bioimaging agents, drug delivery carriers, light-emitting materials, etc. Cucurbit[n]urils comprise another group of cavitands known for their high affinity for various guest molecules. Nonetheless, some aspects of their coordination chemistry remain enigmatic. Although they are recognized as potential biomimetic scaffolds, they are still not tested as metalloenzyme models and not much is known about their metal-binding properties. Furthermore, there is no systematic study on the key factors controlling the processes of metal coordination to these systems. In the computational study herein, DFT molecular modeling has been employed in order to investigate the interactions of biologically essential (mono- and divalent) metal cations to cucurbit[n]urils and evaluate the major determinants shaping the process. The thermodynamic descriptors (Gibbs energies in the gas phase and in a water medium) of the corresponding complexation reactions have been estimated. The results obtained shed light on the mechanism of host-guest recognition and disclose which factors more specifically affect the metal binding process.
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Affiliation(s)
- Nikoleta Kircheva
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences 1113 Sofia Bulgaria
| | - Stefan Dobrev
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences 1113 Sofia Bulgaria
| | - Lyubima Dasheva
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski" 1164 Sofia Bulgaria
| | - Iskra Koleva
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski" 1164 Sofia Bulgaria
| | - Valya Nikolova
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski" 1164 Sofia Bulgaria
| | - Silvia Angelova
- Institute of Optical Materials and Technologies "Acad. J. Malinowski", Bulgarian Academy of Sciences 1113 Sofia Bulgaria
| | - Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski" 1164 Sofia Bulgaria
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Pereva S, Nikolova V, Sarafska T, Angelova S, Spassov T, Dudev T. Inclusion complexes of ibuprofen and β-cyclodextrin: Supramolecular structure and stability. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2019.127575] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Pereva S, Nikolova V, Angelova S, Spassov T, Dudev T. Water inside β-cyclodextrin cavity: amount, stability and mechanism of binding. Beilstein J Org Chem 2019; 15:1592-1600. [PMID: 31435441 PMCID: PMC6664416 DOI: 10.3762/bjoc.15.163] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 07/01/2019] [Indexed: 01/27/2023] Open
Abstract
Cyclodextrins (CDs) are native host systems with inherent ability to form inclusion complexes with various molecular entities, mostly hydrophobic substances. Host cyclodextrins are accommodative to water molecules as well and contain water in the native state. For β-cyclodextrin (β-CD), there is no consensus regarding the number of bound water molecules and the location of their coordination. A number of intriguing questions remain: (1) Which localities of the host’s macrocycle are the strongest attractors for the guest water molecules? (2) What are the stabilizing factors for the water clusters in the interior of β-CD and what type of interactions between water molecules and cavity walls or between the water molecules themselves are dominating the energetics of the β-CD hydration? (3) What is the maximum number of water molecules inside the cavity of β-CD? (4) How do the thermodynamic characteristics of β-CD hydration compare with those of its smaller α-cyclodextrin (α-CD) counterpart? In this study, we address these questions by employing a combination of experimental (DSC/TG) and theoretical (DFT) approaches.
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Affiliation(s)
- Stiliyana Pereva
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski", 1164 Sofia, Bulgaria
| | - Valya Nikolova
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski", 1164 Sofia, Bulgaria
| | - Silvia Angelova
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Tony Spassov
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski", 1164 Sofia, Bulgaria
| | - Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski", 1164 Sofia, Bulgaria
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Simeonova K, Nikolova V, Naseva E, Stoychov M, Yankova T, Donchev M, Arnaudov G, Balazenkou G, Guenova M, Spasov B. PB1756 EFFICACY OF SALVAGE CHEMOTHERAPY REGIMENS IN PATIENTS WITH REFRACTORY OR RELAPSED ACUTE MYELOID LEUKEMIA SINGLE CENTER EXPERIENCE. Hemasphere 2019. [DOI: 10.1097/01.hs9.0000565532.97640.73] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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17
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Alargkof V, Kersten L, Stanislavov R, Nikolova V, Kamenov Z, Nikolinakos P. 515 Sperm DNA integrity in patients with varicocele: relationships between DNA fragmentation and bulk semen parameters. J Sex Med 2018. [DOI: 10.1016/j.jsxm.2018.04.421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
Cyclodextrins (CDs) are among the most widely used native host systems with ability to form inclusion complexes with various molecular objects. This ability is so strong that the "hydrophobic" CD cavity never remains empty, even in the guest-free state it is filled with water molecules. However, no consensus has been reached concerning both the total number of hydrating water molecules and their preferred binding location in the CDs. Several outstanding questions regarding the CD hydration still wait to be answered: (1) Which spots of the CD cavity ("hot spots") have the highest affinity for the guest water molecules? (2) How stable are water clusters inside the cavity? (3) Which mode of water binding, sequential or bulk, is thermodynamically more favored? (4) What is the upper limit of the number of water molecules bound inside the host cavity? (5) What factors do control the CD hydration process? Here, using αCD as a typical representative of the cyclodextrin family, we endeavor to answer these questions by combining experimental measurements (differential scanning calorimetry and thermogravimetry) with theoretical (DFT) calculations. Enthalpies of the αCD hydrate formation are evaluated and the role of different factors, such as the number and mode of binding (sequential vs bulk) of water molecules, type of hydrogen bonds established (water-water vs water-αCD), and the dielectric properties of the medium, on the complexation process is assessed. The results obtained shed light on the intimate mechanism of water binding to αCD and disclose the key factors governing the process.
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Affiliation(s)
- Silvia Angelova
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences , 1113 Sofia, Bulgaria
| | - Valya Nikolova
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski" , 1164 Sofia, Bulgaria
| | - Stiliyana Pereva
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski" , 1164 Sofia, Bulgaria
| | - Tony Spassov
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski" , 1164 Sofia, Bulgaria
| | - Todor Dudev
- Faculty of Chemistry and Pharmacy, Sofia University "St. Kl. Ohridski" , 1164 Sofia, Bulgaria
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Nikolova V, Delimitreva S, Chakarova I, Zhivkova R, Hadzhinesheva V, Markova M. Dynamics of Lamins B and A/C and Nucleoporin Nup160 during Meiotic Maturation in Mouse Oocytes. Folia Biol (Praha) 2017; 63:6-12. [PMID: 28374669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
This study was aimed at elucidating the fate of three important nuclear envelope components - lamins B and A/C and nucleoporin Nup160, during meiotic maturation of mouse oocytes. These proteins were localized by epifluorescence and confocal microscopy using specific antibodies in oocytes at different stages from prophase I (germinal vesicle) to metaphase II. In immature germinal vesicle oocytes, all three proteins were detected at the nuclear periphery. In metaphase I and metaphase II, lamin B co-localized with the meiotic spindle, lamin A/C was found in a diffuse halo surrounding the spindle and to a lesser degree throughout the cytoplasm, and Nup160 was concentrated to the spindle poles. To our knowledge, this is the first report on nucleoporin localization in mammalian oocytes and the first successful detection of lamins in mature oocytes. While the distribution patterns of both lamins closely paralleled the respective stages of mitosis, Nup160 localization in metaphase oocytes corresponded to that in mitotic prometaphase rather than metaphase. The peculiar distribution of this nucleoporin in oocytes may reflect its role in meiosis-specific mechanisms of spindle assembly and its regulation.
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Affiliation(s)
- V Nikolova
- Department of Biology, Medical Faculty, Medical University of Sofia, Bulgaria
| | - S Delimitreva
- Department of Biology, Medical Faculty, Medical University of Sofia, Bulgaria
| | - I Chakarova
- Department of Biology, Medical Faculty, Medical University of Sofia, Bulgaria
| | - R Zhivkova
- Department of Biology, Medical Faculty, Medical University of Sofia, Bulgaria
| | - V Hadzhinesheva
- Department of Biology, Medical Faculty, Medical University of Sofia, Bulgaria
| | - M Markova
- Department of Biology, Medical Faculty, Medical University of Sofia, Bulgaria
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Das RK, Tamman A, Nikolova V, Freeman TP, Bisby JA, Lazzarino AI, Kamboj SK. Nitrous oxide speeds the reduction of distressing intrusive memories in an experimental model of psychological trauma. Psychol Med 2016; 46:1749-1759. [PMID: 26937942 DOI: 10.1017/s003329171600026x] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
BACKGROUND Post-traumatic stress disorder (PTSD) involves maladaptive long-term memory formation which underlies involuntary intrusive thoughts about the trauma. Preventing the development of such maladaptive memory is a key aim in preventing the development of PTSD. We examined whether the N-methyl d-aspartate receptor (NMDAR) antagonist gas nitrous oxide (N2O) could reduce the frequency of intrusive memories by inhibiting NMDAR-dependent memory consolidation in a laboratory analogue of psychological trauma. METHOD Participants were randomized to inhale N2O (N = 25) or medical air (N = 25) after viewing a negatively valenced emotional film clip ('trauma film'). Participants subsequently completed a daily diary assessing frequency of intrusive thoughts relating to the film clip. A week later, participants completed an explicit memory recall task related to the film. RESULTS Post-encoding N2O sped the reduction in intrusive memory frequency, with a significant reduction by the next day in the N2O group compared to 4 days later in the air group. N2O also interacted with post-film dissociation, producing increased intrusion frequency in those who were highly dissociated at baseline. Sleep length and quality the night after viewing the film did not differ between the groups. CONCLUSION N2O speeds the reduction of intrusive analogue trauma memory in a time-dependent manner, consistent with sleep-dependent long-term consolidation disruption. Further research with this drug is warranted to determine its potential to inoculate against enduring effects of psychological trauma; however, caution is also urged in dissociated individuals where N2O may aggravate PTSD-like symptomatology.
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Affiliation(s)
- R K Das
- Clinical Psychopharmacology Unit,UCL,London,UK
| | - A Tamman
- Clinical Psychopharmacology Unit,UCL,London,UK
| | - V Nikolova
- Clinical Psychopharmacology Unit,UCL,London,UK
| | - T P Freeman
- Clinical Psychopharmacology Unit,UCL,London,UK
| | - J A Bisby
- Institute of Cognitive Neuroscience,UCL,London,UK
| | - A I Lazzarino
- London School of Hygiene & Tropical Medicine,London,UK
| | - S K Kamboj
- Clinical Psychopharmacology Unit,UCL,London,UK
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Angelova S, Spassov B, Nikolova V, Christov I, Tzvetkov N, Simeonova M. Does the pattern of clonal evolution in the karyotype of patients with acute myeloid leukemia and myelodysplastic syndromes depend on the type of the primary chromosomal aberrations? CYTOL GENET+ 2015. [DOI: 10.3103/s0095452715040027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Angelova S, Spassov B, Nikolova V, Christov I, Tzvetkov N, Simeonova M. DOES THE PATTERN OF CLONAL EVOLUTION IN THE KARYOTYPE OF PATIENTS WITH ACUTE MYELOID LEUKEMIA AND MYELODYSPLASTIC SYNDROMES DEPEND ON THE TYPE OF THE PRIMARY CHROMOSOMAL ABERRATIONS? Tsitol Genet 2015; 49:17-24. [PMID: 26419065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The aim of our study was to define if the type of primary chromosomal aberrations (CA) of the karyotype of patients with Acute myeloid leukemia (AML) and Myelodysplastic syndromes (MDS) determines the way and the rate of karyotype development. Conventional cytogenetic analysis was carried out on 248 AML and 105 MDS patients at diagnosis. Clonal evolution (CE) was found in 40% (51 of 128) of AML patients and in 47.5% (19 of 40) of MDS patients having CA in their karyotype. The first pattern we established was for the most frequent CA which initiate CE in 28 patients with a complex karyotype. These CA were non-balansed rearrangements in the following regions: 5q, 7q, 11q, 3q, monosomy 5, monosomy 7. The second pattern of CE was regarding the most frequent aneuploidias (+8, +11, +21, -Y, and the third pattern concerned balanced CA. We found significant difference in the distribution of karyotypes in different stages of progression between the first and the other two groups (p < 0.001). No statistical difference was found between the patterns in the second and the third group CA (p > 0.5).
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MESH Headings
- Adolescent
- Adult
- Aged
- Aged, 80 and over
- Bone Marrow/metabolism
- Bone Marrow/pathology
- Chromosome Aberrations
- Chromosomes, Human, Pair 11/chemistry
- Chromosomes, Human, Pair 21/chemistry
- Chromosomes, Human, Pair 5/chemistry
- Chromosomes, Human, Pair 7/chemistry
- Chromosomes, Human, Pair 8/chemistry
- Chromosomes, Human, Y/chemistry
- Clonal Evolution
- Cytogenetic Analysis
- Humans
- Karyotype
- Leukemia, Myeloid, Acute/diagnosis
- Leukemia, Myeloid, Acute/genetics
- Leukemia, Myeloid, Acute/pathology
- Middle Aged
- Myelodysplastic Syndromes/diagnosis
- Myelodysplastic Syndromes/genetics
- Myelodysplastic Syndromes/pathology
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Angelova S, Spassov B, Nikolova V, Christov I, Tzvetkov N, Simeonova M. Is amplification of c-MYC, MLL and RUNX1 genes in AML and MDS patients with trisomy 8, 11 and 21 a factor for a clonal evolution in the karyotype? CYTOL GENET+ 2015. [DOI: 10.3103/s0095452715030032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Nikolova V, Galabov B. Effects of structural variations on the hydrogen bond pairing between adenine derivatives and thymine. Maced J Chem Chem Eng 2015. [DOI: 10.20450/mjcce.2015.644] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
<p><strong>Abstract:</strong><strong> </strong>The hydrogen bonding between substituted adenines and thymine was investigated by density functional theory computations at the B3LYP/6-311+G(2d,2p) level. The effect of 20 different polar substituents at position 8 in adenine was examined in detail. Three different theoretical parameters, reflecting the electrostatics at the atoms involved in hydrogen bonding, were applied. An excellent correlation between electrostatic potentials at the bonding atoms in the monomer adenines and interaction energies was derived (Eqn. 2). It can be employed in designing bioactive adenine derivatives that are able to bind with a finely adjusted strength to thymine bioreceptor sites. NBO and Hirshfeld atomic charges are found to be less successful as reactivity predictors in these interactions.</p>
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Petakov D, Ivanov P, Nikolova V. Correlations of Oil Content and Fatty Acid Composition in High Oleic Lines and Hybrids of Sunflower (H. Annuus L.). BIOTECHNOL BIOTEC EQ 2014. [DOI: 10.1080/13102818.1993.10818724] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Delimitreva S, Wedi E, Bakker J, Tkachenko OY, Nikolova V, Nayudu PL. Numerical chromosome disorders in the common marmoset (Callithrix jacchus)--comparison between two captive colonies. J Med Primatol 2013; 42:177-85. [PMID: 23600894 DOI: 10.1111/jmp.12050] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/22/2013] [Indexed: 11/29/2022]
Abstract
BACKGROUND Chromosomal analyses were performed for marmosets from two colonies - Deutsches Primatenzentrum (DPZ) and Biomedical Primate Research Centre (BPRC). Chlorine-based disinfectants are used in DPZ; no chemical disinfection is applied in BPRC. METHODS The rates of chromosomal non-disjunction, polyploidy and endoreduplication were investigated after G-banding. RESULTS For DPZ monkeys, the mean rates of non-disjunction were 7.6% for bone marrow and 11.3% for lymphocytes. The polyploidy level was 2.5% in bone marrow and 0.8% in blood. Frequency of endoreduplication in bone marrow and in leucocytes was 0.5% and 0.8%, respectively. For BPRC, the rate of non-disjunction in leucocytes (1.3%) was significantly lower than that for DPZ; the polyploidy rate (0.2%) in blood was lower than that in DPZ; endoreduplication was not observed. CONCLUSION The levels of chromosomal disorders are elevated for DPZ colony. We suggest that the increased rate of chromosomal disorders in DPZ marmosets can be related to the chemical disinfection of their environment.
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Affiliation(s)
- S Delimitreva
- Laboratory of Reproductive Biomedicine, German Primate Center, Goettingen, Germany.
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Zhivkova R, Panevska M, Delimitreva S, Markova M, Nikolova V, Chakarova I, Tenev T, Hadzhinesheva V, Mainhard K, Vatev I. [Investigation of cytokeratin and vimentin intermediate filaments in polycystic ovaries (PCOS) -- presence and specific structure of Balbiani body in primordial follicles]. Akush Ginekol (Sofiia) 2013; 52:7-12. [PMID: 24505633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Despite of the importance of cytoskeletal proteins for ovarian function and pathology, very few studies have addressed the presence and distribution of these proteins in polycystic ovaries. We investigated sections of human polycystic ovarian tissue for vimentin and a set of cytokeratins by epifluorescence. The studied proteins showed strong colocalization. Positive reaction was detected in two main ovarian compartments: with weak intensity in follicular cells and very strong in perinuclear position in oocytes of primordial follicles. Epifluorescent study of the oocytes from primordial follicles allowed us to identify the immunopositive structure in oocytes as Balbiani body, a transient organelle responsible for establishing oocyte polarity and ooplasm gradients in nonmammalian vertebrates. Our results suggest functional interaction of different types of cytoplasmic intermediate filament proteins in polycystic ovaries and a possible importance of the Balbiani body for human oogenesis in norm and pathology.
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Nikolova V, Shivarov V, Angelova S. 125 Flow cytometry contributes to distinguish between myelodysplastic syndromes and uncertain cytopenias. Leuk Res 2011. [DOI: 10.1016/s0145-2126(11)70127-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Petkova V, Nikolova V, Kalapchieva S, Stoeva V, Topalova E, Angelova S. PHYSIOLOGICAL RESPONSE AND POLLEN VIABILITY OF PISUM SATIVUM GENOTYPES UNDER HIGH TEMPERATURE INFLUENCE. ACTA ACUST UNITED AC 2009. [DOI: 10.17660/actahortic.2009.830.96] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Stanislavov R, Nikolova V, Rohdewald P. Improvement of seminal parameters with Prelox: a randomized, double-blind, placebo-controlled, cross-over trial. Phytother Res 2009; 23:297-302. [PMID: 19142978 DOI: 10.1002/ptr.2592] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In a randomly allocated, double-blind, placebo-controlled, cross-over design, 50 infertile patients were treated for 1 month with placebo or a combination of l-arginine aspartate and Pycnogenol (Prelox). Semen samples were examined at 4 week intervals according to WHO criteria. Treatment with Prelox increased significantly the semen volume, concentration of spermatozoa, percentage of motile spermatozoa and percentage of spermatozoa with normal morphology compared with placebo. The placebo had no influence on the parameters of seminological analysis. Intake of Pycnogenol for 1 month improved the fertility index to normal values. After treatment, the fertility index decreased again to infertile status. No unwanted effects were reported. Prelox seems to be a promising alternative to treat patients with mild infertility.
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Affiliation(s)
- R Stanislavov
- Medical University Sofia, Faculty of Medicine, Department of Obstetrics and Gynecology, Sofia, Bulgaria
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Tonchev A, Rancic G, Fiore M, Tuncel N, Kostov D, Valchanov K, Ghenev P, Pancheva R, Panayotov P, Georgieva Z, Nikolova V, Peneva V, Petrovic A, Stoev S, Yamori Y, Aloe L, Chaldakov G. PERIADVENTITIAL ADIPOSE TISSUE (TUNICA ADIPOSA): A FRIEND-AND-FOE CONCEPT OF ATHEROGENESIS. ATHEROSCLEROSIS SUPP 2008. [DOI: 10.1016/s1567-5688(08)70907-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Götte M, Nikolova V, Yip GW, Smollich M, Fischgräbe J, Ibrahim SA, Wülfing P, Kiesel L. Die lösliche Form des prognostischen Markers Syndecan-1 fördert die Invasivität von Mammakarzinomzellen durch einen TIMP-1- und E-Cadherin-abhängigen Mechanismus. Geburtshilfe Frauenheilkd 2008. [DOI: 10.1055/s-2008-1075750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Stanislavov R, Nikolova V, Rohdewald P. Improvement of erectile function with Prelox: a randomized, double-blind, placebo-controlled, crossover trial. Int J Impot Res 2007; 20:173-80. [PMID: 17703218 DOI: 10.1038/sj.ijir.3901597] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
In a randomly allocated, double-blind, placebo-controlled, crossover design, 50 patients with mild to moderate erectile dysfunction (ED) were treated for 1 month with placebo or a combination of L-arginine aspartate and Pycnogenol (Prelox). Patients reported sexual function from diaries. Testosterone levels and endothelial NO synthase (e-NOS) were monitored along with routine clinical chemistry. Intake of Pycnogenol for 1 month restored erectile function to normal. Intercourse frequency doubled. e-NOS in spermatozoa and testosterone levels in blood increased significantly. Cholesterol levels and blood pressure were lowered. No unwanted effects were reported. Prelox is a promising alternative to treat mild to moderate ED.
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Affiliation(s)
- R Stanislavov
- Department of Obstetrics and Gynecology, Medical University Sofia, Faculty of Medicine, Sofia, Bulgaria
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Chaldakov GN, Tonchev AB, Manni L, Hristova MG, Nikolova V, Fiore M, Vyagova D, Peneva VN, Aloe L. Comment on: Krabbe KS, Nielsen AR, Krogh-Madsen R et al (2007) Brain-derived neurotrophic factor (BDNF) and type 2 diabetes. Diabetologia 50:431-438. Diabetologia 2007; 50:1781-2. [PMID: 17546439 DOI: 10.1007/s00125-007-0706-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Accepted: 04/10/2007] [Indexed: 01/18/2023]
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Götte M, Nikolova V, Rossi L, Smollich M, Fischgraebe J, Wülfing P, Kiesel L. Differentieller Einfluss membrangebundener und löslicher Formen von Syndecan-1 (CD138) auf die Proliferation und Invasivität von Mammakarzinomzellen in vitro. Geburtshilfe Frauenheilkd 2007. [DOI: 10.1055/s-2007-983663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Nikolova V, Stanislavov R, Vatev I, Nalbanski B, Pŭnevska M. [Sperm parameters in male idiopathic infertility after treatment with prelox]. Akush Ginekol (Sofiia) 2007; 46:7-12. [PMID: 17974175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
UNLABELLED The diagnosis of male infertility is determinate after assessment of sperm quality and clinical study. In nearly 30% of the cases nevertheless detailed clinical and laboratory study it can't be discovered the cause and on the bases of exclusion criteria set the diagnosis idiopathic infertility. The object of our study was investigation of the group patients (n=50) with idiopathic infertility treated with Prelox and to be studied its effects on spermatozoa parameters. MATERIAL AND METHODS The study design was double-blind, placebo-controlled, cross-over, randomized study, including introduction period (1 month), two therapeutic periods (each one of 1 month) separated with 1 month wash out period and concluding period of 1 month. There was applied a new method for treatment with mechanism of action stimulation the production cGMP of spermatozoa endothelial nitric oxide synthase (eNOS). This is not surprising achieving results show improvement of sperm quality. The methods of the study were: 1. Assessment of the conventional semen analysis (according the criteria of WHO, 1999). 2. Spermatozoa function tests. 3. Spermatozoa-cervical mucus penetration tests. RESULTS The obtained results showed improvement of sperm quality, in the middle-aged men the therapeutic answers was better than in younger. In conclusion the therapy with Prelox improve sperm parameters in men with idiopathic infertility. Pycnogenol (one of the constituents of Prelox) has powerful antioxidative influence ameliorating spermatozoa function.
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Neshkova MT, Nikolova V, Petrov V. New real-time analytical applications of electrochemical quartz crystal microbalance Stoichiometry and phase composition monitoring of electrodeposited thin chalcogenide films. Anal Chim Acta 2006; 573-574:34-40. [PMID: 17723502 DOI: 10.1016/j.aca.2005.12.070] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2005] [Revised: 11/29/2005] [Accepted: 12/29/2005] [Indexed: 11/17/2022]
Abstract
The electrochemical quartz crystal microbalance (EQCM) has recently gained increasing popularity as a powerful tool for electrochemical interface examinations. This paper reports on its great potential for developing new real-time analytical protocols. Potentiostatic coulometry is used in conjunction with quartz crystal microgravimetry (QCMg) with controlled hydrodynamics to develop two new analytical procedures: real-time stoichiometry monitoring of electrodeposited binary chalcogenide films and phase composition quantification of electrodeposited ternary chalcogenide compounds. The newly developed EQCM methods are illustrated on the examples of Ag2+deltaSe-electrodeposited films and the electroformation of ternary CuAgSe-films. Both compounds have been successfully used as ion-selective membranes for flow-injection detectors. The experimental set-up including hydrodynamic control, the main strategy of the approach used and its scope and limitations are broadly discussed. The obtained data allow for real time profile monitoring of either stoichiometry (Ag2+deltaSe-case) or phase composition (CuAgSe-case).
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Affiliation(s)
- Milka T Neshkova
- Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G.Bonchev str. bl.11, 1113 Sofia, Bulgaria.
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Drachev D, Nikolova V. Comparative Technological Study of the Tobacco of Burley Variety Group Grown in Bulgaria. BIOTECHNOL BIOTEC EQ 2006. [DOI: 10.1080/13102818.2006.10817365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Nikolova V. [Assessment of sperm quality as a male factor in couple's infertility]. Akush Ginekol (Sofiia) 2006; 45:40-7. [PMID: 17168496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The purpose of the present review is to present laboratory assessment of some studies of human seminal fluid and spermatozoa - cervical-mucus interactions according the last (the fourth edition) of WHO guideline, 1999. There are discussed additional tests for spermatozoa function in connection with male factor in couple's infertility. It is outlined the signification of calculation of some spermatozoa indices for clinical practice. The assessment built on the entire population spermatozoa defines the fertility ability of the small portion spermatozoa reaching the oocyte and leading to fertilization.
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Chaldakov G, Manni L, Nikolova V, Vyagova D, Aloe L. Mo-P2:181 Neurotrophins and acute coronary syndromes. ATHEROSCLEROSIS SUPP 2006. [DOI: 10.1016/s1567-5688(06)80316-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Nikolova V, Vatev I, Stanislavov R, Nalbanski B, Pŭnevska M, Ivanov S, Batashki I. [Selecting function of female genital tract in relation with spermatozoa interaction]. Akush Ginekol (Sofiia) 2006; 45:47-9. [PMID: 17489168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The present study includes 50 infertile couples followed sperm parameters: morphology and others indices for ability of penetration in ovulatory cervical mucus during 12 months. It is discussed the possibility of which spermatozoa can participate in the fertilization and the impotence and place of the female genital tract for the selection of morphologically abnormal spermatozoa before reaching the place of fertilization.
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Drachev D, Nikolova V, Nikolov N. Technological Study on Tobaccos of Basmi Group Variety Grown in Different Regions of Bulgaria. BIOTECHNOL BIOTEC EQ 2005. [DOI: 10.1080/13102818.2005.10817250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Nikolova V, Drachev D. Study on Tobacco Quality of Virginia Variety Group Grown in Bulgaria Technological Study on the Quality of Virginia Tobacco Introduced Varieties Grown in the Districts of South Bulgaria (Part I). BIOTECHNOL BIOTEC EQ 2005. [DOI: 10.1080/13102818.2005.10817187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Drachev D, Nikolova V. Study on Tobacco Quality of Virginia Variety Group Grown in Bulgaria Technological Study on the Quality of Virginia Tobacco Introduced Varieties Grown in the Districts of North Bulgaria (Part II). BIOTECHNOL BIOTEC EQ 2005. [DOI: 10.1080/13102818.2005.10817188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Nikolova V, Drachev D, Nikolov N. Technological Study on Tobaccos of Basmi Group Variety Grown in Different Regions of Bulgaria. BIOTECHNOL BIOTEC EQ 2005. [DOI: 10.1080/13102818.2005.10817251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Drachev D, Nikolova V, Petrova V, Shumarski N. Investigation Burley Tobacco Quality in Horizontal Stalk Cut Curing and Using of Desiccants. BIOTECHNOL BIOTEC EQ 2004. [DOI: 10.1080/13102818.2004.10817121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Nikolova V, Drachev D, Nikolov N. Investigation on Virginia Tobacco Quality. BIOTECHNOL BIOTEC EQ 2004. [DOI: 10.1080/13102818.2004.10817122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Abstract
Penile erection requires the relaxation of the cavernous smooth muscle, which is triggered by nitric oxide (NO). We investigated the possibility of overcoming erectile dysfunction (ED) by increasing the amounts of endogenous NO. For this purpose, we orally administered Pycnogenol, because it is known to increase production of NO by nitric oxide syntase together with L-arginine as substrate for this enzyme. The study included 40 men, aged 25-45 years, without confirmed organic erectile dysfunction. Throughout the 3-month trial period, patients received 3 ampoules Sargenor a day, a drinkable solution of the dipeptide arginyl aspartate (equivalent to 1.7 g L-arginine per day). During the second month, patients were additionally supplemented with 40 mg Pycnogenol two times per day; during the third month, the daily dosage was increased to three 40-mg Pycnogenol tablets. We obtained a sexual function questionnaire and a sexual activity diary from each patient. After 1 month of treatment with L-arginine, a statistically nonsignificant number of 2 patients (5%) experienced a normal erection. Treatment with a combination of L-arginine and Pycnogenol for the following month increased the number of men with restored sexual ability to 80%. Finally, after the third month of treatment, 92.5% of the men experienced a normal erection. We conclude that oral administration of L-arginine in combination with Pycnogenol causes a significant improvement in sexual function in men with ED without any side effects.
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Affiliation(s)
- R Stanislavov
- Seminological Laboratory SBALAG, Maichin Dom, Sofia, Bulgaria.
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