@article{ShityakovSalvadorPastorinetal.2015, author = {Shityakov, Sergey and Salvador, Ellaine and Pastorin, Giorgia and F{\"o}rster, Carola}, title = {Blood-brain barrier transport studies, aggregation, and molecular dynamics simulation of multiwalled carbon nanotube functionalized with fluorescein isothiocyanate}, series = {International Journal of Nanomedicine}, volume = {10}, journal = {International Journal of Nanomedicine}, doi = {10.2147/IJN.S68429}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-149233}, pages = {1703-1713}, year = {2015}, abstract = {In this study, the ability of a multiwalled carbon nanotube functionalized with fluorescein isothiocyanate (MWCNT-FITC) was assessed as a prospective central nervous system-targeting drug delivery system to permeate the blood-brain barrier. The results indicated that the MWCNT-FITC conjugate is able to penetrate microvascular cerebral endothelial monolayers; its concentrations in the Transwell® system were fully equilibrated after 48 hours. Cell viability test, together with phase-contrast and fluorescence microscopies, did not detect any signs of MWCNT-FITC toxicity on the cerebral endothelial cells. These microscopic techniques also revealed presumably the intracellular localization of fluorescent MWCNT-FITCs apart from their massive nonfluorescent accumulation on the cellular surface due to nanotube lipophilic properties. In addition, the 1,000 ps molecular dynamics simulation in vacuo discovered the phenomenon of carbon nanotube aggregation driven by van der Waals forces via MWCN-TFITC rapid dissociation as an intermediate phase.}, language = {en} } @article{ShityakovDandekarFoerster2015, author = {Shityakov, Sergey and Dandekar, Thomas and F{\"o}rster, Carola}, title = {Gene expression profiles and protein-protein interaction network analysis in AIDS patients with HIV-associated encephalitis and dementia}, series = {HIV/AIDS: Research and Palliative Care}, volume = {7}, journal = {HIV/AIDS: Research and Palliative Care}, doi = {10.2147/HIV.S88438}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-149494}, pages = {265-276}, year = {2015}, abstract = {Central nervous system dysfunction is an important cause of morbidity and mortality in patients with human immunodeficiency virus type 1 (HIV-1) infection and acquired immunodeficiency virus syndrome (AIDS). Patients with AIDS are usually affected by HIV-associated encephalitis (HIVE) with viral replication limited to cells of monocyte origin. To examine the molecular mechanisms underlying HIVE-induced dementia, the GSE4755 Affymetrix data were obtained from the Gene Expression Omnibus database and the differentially expressed genes (DEGs) between the samples from AIDS patients with and without apparent features of HIVE-induced dementia were identified. In addition, protein-protein interaction networks were constructed by mapping DEGs into protein-protein interaction data to identify the pathways that these DEGs are involved in. The results revealed that the expression of 1,528 DEGs is mainly involved in the immune response, regulation of cell proliferation, cellular response to inflammation, signal transduction, and viral replication cycle. Heat-shock protein alpha, class A member 1 (HSP90AA1), and fibronectin 1 were detected as hub nodes with degree values >130. In conclusion, the results indicate that HSP90A and fibronectin 1 play important roles in HIVE pathogenesis.}, language = {en} } @article{ShityakovSohajdaPuskasetal.2014, author = {Shityakov, Sergey and Sohajda, Tam{\´a}s and Puskas, Istav{\´a}n and Roewer, Norbert and F{\"o}rster, Carola and Broscheit, Jens-Albert}, title = {Ionization States, Cellular Toxicity and Molecular Modeling Studies of Midazolam Complexed with Trimethyl-β-Cyclodextrin}, series = {Molecules}, volume = {19}, journal = {Molecules}, number = {10}, doi = {10.3390/molecules191016861}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-119186}, pages = {16861-76}, year = {2014}, abstract = {We investigated the ionization profiles for open-ring (OR) and closed-ring (CR) forms of midazolam and drug-binding modes with heptakis-(2,3,6-tri-O-methyl)-β-cyclodextrin (trimethyl-β-cyclodextrin; TRIMEB) using molecular modeling techniques and quantum mechanics methods. The results indicated that the total net charges for different molecular forms of midazolam tend to be cationic for OR and neutral for CR at physiological pH levels. The thermodynamic calculations demonstrated that CR is less water-soluble than OR, mainly due to the maximal solvation energy (ΔG(CR)(solv = -9.98 kcal·mol ⁻¹), which has a minimal ΔG(OR)(solv) of -67.01 kcal·mol⁻¹. A cell viability assay did not detect any signs of TRIMEB and OR/CR-TRIMEB complex toxicity on the cEND cells after 24 h of incubation in either Dulbecco's Modified Eagles Medium or in heat-inactivated human serum. The molecular docking studies identified the more flexible OR form of midazolam as being a better binder to TRIMEB with the fluorophenyl ring introduced inside the amphiphilic cavity of the host molecule. The OR binding affinity was confirmed by a minimal Gibbs free energy of binding (ΔG(bind)) value of -5.57 ± 0.02 kcal·mol⁻¹, an equilibrium binding constant (K(b)) of 79.89 ± 2.706 μM, and a ligand efficiency index (LE(lig)) of -0.21 ± 0.001. Our current data suggest that in order to improve the clinical applications of midazolam via its complexation with trimethyl-β-cyclodextrin to increase drug's overall aqueous solubility, it is important to concern the different forms and ionization states of this anesthetic. All mean values are indicated with their standard deviations.}, language = {en} } @article{ShityakovFoerster2014, author = {Shityakov, Sergey and F{\"o}rster, Carola}, title = {In silico predictive model to determine vector-mediated transport properties for the blood-brain barrier choline transporter}, series = {Advances and Applications in Bioinformatics and Chemistry}, volume = {7}, journal = {Advances and Applications in Bioinformatics and Chemistry}, doi = {10.2147/AABC.S63749}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-120200}, pages = {23-36}, year = {2014}, abstract = {The blood-brain barrier choline transporter (BBB-ChT) may have utility as a drug delivery vector to the central nervous system (CNS). We therefore initiated molecular docking studies with the AutoDock and AutoDock Vina (ADVina) algorithms to develop predictive models for compound screening and to identify structural features important for binding to this transporter. The binding energy predictions were highly correlated with r2=0.88, F=692.4, standard error of estimate =0.775, and P-value<0.0001 for selected BBB-ChT-active/inactive compounds (n=93). Both programs were able to cluster active (Gibbs free energy of binding <-6.0 kcal*mol-1) and inactive (Gibbs free energy of binding >-6.0 kcal*mol-1) molecules and dock them significantly better than at random with an area under the curve value of 0.86 and 0.84, respectively. In ranking smaller molecules with few torsional bonds, a size-related bias in scoring producing false-negative outcomes was detected. Finally, important blood-brain barrier parameters, such as the logBBpassive and logBBactive values, were assessed to predict compound transport to the CNS accurately. Knowledge gained from this study is useful to better understand the binding requirements in BBB-ChT, and until such time as its crystal structure becomes available, it may have significant utility in developing a highly predictive model for the rational design of drug-like compounds targeted to the brain.}, language = {en} } @article{ShityakovFoerster2014, author = {Shityakov, Sergey and F{\"o}rster, Carola}, title = {In silico structure-based screening of versatile P-glycoprotein inhibitors using polynomial empirical scoring functions}, series = {Advances and Applications in Bioinformatics and Chemistry}, volume = {7}, journal = {Advances and Applications in Bioinformatics and Chemistry}, doi = {10.2147/AABC.S56046}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-120214}, pages = {1-9}, year = {2014}, abstract = {P-glycoprotein (P-gp) is an ATP (adenosine triphosphate)-binding cassette transporter that causes multidrug resistance of various chemotherapeutic substances by active efflux from mammalian cells. P-gp plays a pivotal role in limiting drug absorption and distribution in different organs, including the intestines and brain. Thus, the prediction of P-gp-drug interactions is of vital importance in assessing drug pharmacokinetic and pharmacodynamic properties. To find the strongest P-gp blockers, we performed an in silico structure-based screening of P-gp inhibitor library (1,300 molecules) by the gradient optimization method, using polynomial empirical scoring (POLSCORE) functions. We report a strong correlation (r2=0.80, F=16.27, n=6, P<0.0157) of inhibition constants (Kiexp or pKiexp; experimental Ki or negative decimal logarithm of Kiexp) converted from experimental IC50 (half maximal inhibitory concentration) values with POLSCORE-predicted constants (KiPOLSCORE or pKiPOLSCORE), using a linear regression fitting technique. The hydrophobic interactions between P-gp and selected drug substances were detected as the main forces responsible for the inhibition effect. The results showed that this scoring technique might be useful in the virtual screening and filtering of databases of drug-like compounds at the early stage of drug development processes.}, language = {en} } @article{ShityakovPuskasRoeweretal.2014, author = {Shityakov, Sergey and Pusk{\´a}s, Istv{\´a}n and Roewer, Norbert and F{\"o}rster, Carola and Broscheit, Jens}, title = {Three-dimensional quantitative structure-activity relationship and docking studies in a series of anthocyanin derivatives as cytochrome P450 3A4 inhibitors}, series = {Advances and Applications in Bioinformatics and Chemistry}, volume = {7}, journal = {Advances and Applications in Bioinformatics and Chemistry}, doi = {10.2147/AABC.S56478}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-120226}, pages = {11-21}, year = {2014}, abstract = {The cytochrome P450 (CYP)3A4 enzyme affects the metabolism of most drug-like substances, and its inhibition may influence drug safety. Modulation of CYP3A4 by flavonoids, such as anthocyanins, has been shown to inhibit the mutagenic activity of mammalian cells. Considering the previous investigations addressing CYP3A4 inhibition by these substances, we studied the three-dimensional quantitative structure-activity relationship (3D-QSAR) in a series of anthocyanin derivatives as CYP3A4 inhibitors. For the training dataset (n=12), comparative molecular field analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA) yielded crossvalidated and non-crossvalidated models with a q (2) of 0.795 (0.687) and r (2) of 0.962 (0.948), respectively. The models were also validated by an external test set of four compounds with r (2) of 0.821 (CoMFA) and r (2) of 0.812 (CoMSIA). The binding affinity modes associated with experimentally derived IC50 (half maximal inhibitory concentration) values were confirmed by molecular docking into the CYP3A4 active site with r (2) of 0.66. The results obtained from this study are useful for a better understanding of the effects of anthocyanin derivatives on inhibition of carcinogen activation and cellular DNA damage.}, language = {en} } @article{ShityakovHayashiStoerketal.2021, author = {Shityakov, Sergey and Hayashi, Kentaro and St{\"o}rk, Stefan and Scheper, Verena and Lenarz, Thomas and F{\"o}rster, Carola Y.}, title = {The conspicuous link between ear, brain and heart - Could neurotrophin-treatment of age-related hearing loss help prevent Alzheimer's disease and associated amyloid cardiomyopathy?}, series = {Biomolecules}, volume = {11}, journal = {Biomolecules}, number = {6}, issn = {2218-273X}, doi = {10.3390/biom11060900}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-241084}, year = {2021}, abstract = {Alzheimer's disease (AD), the most common cause of dementia in the elderly, is a neurodegenerative disorder associated with neurovascular dysfunction and cognitive decline. While the deposition of amyloid β peptide (Aβ) and the formation of neurofibrillary tangles (NFTs) are the pathological hallmarks of AD-affected brains, the majority of cases exhibits a combination of comorbidities that ultimately lead to multi-organ failure. Of particular interest, it can be demonstrated that Aβ pathology is present in the hearts of patients with AD, while the formation of NFT in the auditory system can be detected much earlier than the onset of symptoms. Progressive hearing impairment may beget social isolation and accelerate cognitive decline and increase the risk of developing dementia. The current review discusses the concept of a brain-ear-heart axis by which Aβ and NFT inhibition could be achieved through targeted supplementation of neurotrophic factors to the cochlea and the brain. Such amyloid inhibition might also indirectly affect amyloid accumulation in the heart, thus reducing the risk of developing AD-associated amyloid cardiomyopathy and cardiovascular disease.}, language = {en} } @article{ShityakovBroscheitFoerster2013, author = {Shityakov, Sergey and Broscheit, Jens and F{\"o}rster, Carola}, title = {Multidrug resistance protein P-gp interaction with nanoparticles (fullerenes and carbon nanotube) to assess their drug delivery potential: a theoretical molecular docking study.}, series = {International journal of computational biology and drug design}, volume = {6}, journal = {International journal of computational biology and drug design}, number = {4}, doi = {10.1504/IJCBDD.2013.056801}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-132089}, pages = {343-357}, year = {2013}, abstract = {P-glycoprotein (P-gp)-mediated efflux system plays an important role to maintain chemical balance in mammalian cells for endogenous and exogenous chemical compounds. However, despite the extensive characterisation of P-gp potential interaction with drug-like molecules, the interaction of carbon nanoparticles with this type of protein molecule is poorly understood. Thus, carbon nanoparticles were analysed, such as buckminsterfullerenes (C20, C60, C70), capped armchair single-walled carbon nanotube (SWCNT or C168), and P-gp interactions using different molecular docking techniques, such as gradient optimisation algorithm (ADVina), Lamarckian genetic algorithm (FastDock), and shape-based approach (PatchDock) to estimate the binding affinities between these structures. The theoretical results represented in this work show that fullerenes might be P-gp binders because of low levels of Gibbs free energy of binding (ΔG) and potential of mean force (PMF) values. Furthermore, the SWCNT binding is energetically unfavourable, leading to a total decrease in binding affinity by elevation of the residual area (Ares), which also affects the π-π stacking mechanisms. Further, the obtained data could potentially call experimental studies using carbon nanostructures, such as SWCNT for development of drug delivery vehicles, to administer and assess drug-like chemical compounds to the target cells since organisms probably did not develop molecular sensing elements to detect these types of carbon molecules.}, language = {en} } @article{SalvadorShityakovFoerster2013, author = {Salvador, Ellaine and Shityakov, Sergey and F{\"o}rster, Carola}, title = {Glucocorticoids and endothelial cell barrier function}, series = {Cell and Tissue Research}, volume = {355}, journal = {Cell and Tissue Research}, number = {3}, doi = {10.1007/s00441-013-1762-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-132091}, pages = {597-605}, year = {2013}, abstract = {Glucocorticoids (GCs) are steroid hormones that have inflammatory and immunosuppressive effects on a wide variety of cells. They are used as therapy for inflammatory disease and as a common agent against edema. The blood brain barrier (BBB), comprising microvascular endothelial cells, serves as a permeability screen between the blood and the brain. As such, it maintains homeostasis of the central nervous system (CNS). In many CNS disorders, BBB integrity is compromised. GC treatment has been demonstrated to improve the tightness of the BBB. The responses and effects of GCs are mediated by the ubiquitous GC receptor (GR). Ligand-bound GR recognizes and binds to the GC response element located within the promoter region of target genes. Transactivation of certain target genes leads to improved barrier properties of endothelial cells. In this review, we deal with the role of GCs in endothelial cell barrier function. First, we describe the mechanisms of GC action at the molecular level. Next, we discuss the regulation of the BBB by GCs, with emphasis on genes targeted by GCs such as occludin, claudins and VE-cadherin. Finally, we present currently available GC therapeutic strategies and their limitations.}, language = {en} } @article{ShityakovFoerster2013, author = {Shityakov, Sergey and F{\"o}rster, Carola}, title = {Pharmacokinetic Delivery and Metabolizing Rate of Nicardipine Incorporated in Hydrophilic and Hydrophobic Cyclodextrins Using Two-Compartment Mathematical Model}, series = {The Scientific World Journal}, volume = {2013}, journal = {The Scientific World Journal}, number = {131358}, doi = {10.1155/2013/131358}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-130519}, pages = {9}, year = {2013}, abstract = {The dispersion routes of cyclodextrin complexes with nicardipine (NC), such as hydrophilic hydroxypropyl-\(\beta\)-cyclodextrin (NC/HP\(\beta\)CD) and hydrophobic triacetyl-\(\beta\)-cyclodextrin (NC/TA\(\beta\)CD), through the body for controlled drug delivery and sustained release have been examined. The two-compartment pharmacokinetic model described the mechanisms of how the human body handles with ingestion of NC-cyclodextrin complexes in gastrointestinal tract (GI), distribution in plasma, and their metabolism in the liver. The model showed that drug bioavailability was significantly improved after oral administration of cyclodextrin complexes. The mathematical significance of this study to predict nicardipine delivery using pharmacokinetic two-compartment mathematical model with linear ordinary differential equations (ODE) approach represents a valuable tool to emphasize its effectiveness and metabolizing rate and diminish the side effects.}, language = {en} }