Publications by authors named "Angelov I"

2-Carbamido-1,3-indanedione (CAID) is a fluorescent compound, existing in two tautomeric forms: A and B. Spectroscopic features of CAID suggest that the tautomeric equilibrium is possible both in ground and excited state. To further elucidate this, measurements of UV-Vis absorption and fluorescence spectra were recorded in various solvents.

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We present a novel method to construct particle accelerators targeting light atoms and nuclei using high-power femtosecond laser pulses. Initially, we confine light atoms within the laser pulse envelope due to longitudinal polarization forces, allowing them to acquire kinetic energies of several GeV. Subsequently, an external electric field separates the nuclei at the cathode, concentrating helium nuclei in a small area.

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Dithienylethenes (DTE) are a rare class of photoswitches, which are capable of undergoing a fast photochemical cyclization leading to increased aromaticity of the closed isomer. At the same time in most of the tautomeric compounds the tautomeric state is strongly affected by the change in the aromaticity of the involved aromatic rings. Very recently it has been shown that the implementation of DTE moiety in salicylideneaniline leads to switching of the stable open form enol tautomer to thermodynamically stable keto tautomer upon cyclization.

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Importance: Cardiovascular disease (CVD) and cancer are the leading causes of mortality in the US. Large-scale population-based and mechanistic studies support a direct effect of CVD on accelerated tumor growth and spread, specifically in breast cancer.

Objective: To assess whether individuals presenting with advanced breast cancers are more likely to have prevalent CVD compared with those with early-stage breast cancers at the time of diagnosis.

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The effect of the external electric field on the ground-state tautomerism in 8-(benzo[d]thiazol-2-yl)quinolin-7-ol has been studied by using density functional theory. The compound exists as an enol tautomer (off state) and under the influence of the external electric field a long-range intramolecular proton transfer can occur, placing the tautomeric proton at the quinolyl nitrogen atom (on state). This is a result of the much higher dipole moment of the end keto tautomer and indicates that the external electric field can be used to mimic the implicit solvent effect in tautomeric systems.

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Background: Epidemiological and mechanistic data support a potential causal link between cardiovascular disease (CVD) and cancer. Abdominal aortic aneurysms (AAAs) represent a common form of CVD with at least partially distinct genetic and biologic pathogenesis from other forms of CVD. The risk of cancer and how this risk differs compared with other forms of CVD, is unknown among AAA patients.

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Herein, we demonstrate a working prototype of a conjugated proton crane, a reversible tautomeric switching molecule in which truly intramolecular long-range proton transfer occurs in solution at room temperature. The system consists of a benzothiazole rotor attached to a 7-hydroxy quinoline stator. According to the experimental and theoretical results, the OH proton is delivered under irradiation to the quinolyl nitrogen atom through a series of consecutive proton transfer and twisting steps.

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The central hypothesis for the development of glioblastoma multiforme (GBM) postulates that the tumor begins its development by transforming neural stem cells into cancer stem cells (CSC). Recently, it has become clear that another kind of stem cell, the mesenchymal stem cell (MSC), plays a role in the tumor stroma. Mesenchymal stem cells, along with their typical markers, can express neural markers and are capable of neural transdifferentiation.

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Photodynamic therapy (PDT) is a curative method, firstly developed for cancer therapy with fast response after treatment and minimum side effects. Two zinc(II) phthalocyanines (3ZnPc and 4ZnPc) and a hydroxycobalamin (Cbl) were investigated on two breast cancer cell lines (MDA-MB-231 and MCF-7) in comparison to normal cell lines (MCF-10 and BALB 3T3). The novelty of this study is a complex of non-peripherally methylpyridiloxy substituted Zn(II) phthalocyanine (3ZnPc) and the evaluation of the effects on different cell lines due to the addition of second porphyrinoid such as Cbl.

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Objective: There is currently no consensus regarding the appropriate lower instrumented vertebra (LIV) for multilevel posterior cervical fusion (PCF) constructs between C7 and crossing the cervicothoracic junction (CTJ). The goal of the present study was to compare postoperative sagittal alignment and functional outcomes among adult patients presenting with cervical myelopathy undergoing multilevel PCF terminating at C7 versus spanning the CTJ.

Methods: A single-institution retrospective analysis (January 2017-December 2018) was performed of patients undergoing multilevel PCF for cervical myelopathy that involved the C6-7 vertebrae.

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In this review, we have attempted to briefly summarize the influence of an external electric field on an assembly of tautomeric molecules and to what experimentally observable effects this interaction can lead to. We have focused more extensively on the influence of an oriented external electric field (OEEF) on excited-state intramolecular proton transfer (ESIPT) from the studies available to date. The possibilities provided by OEEF for regulating several processes and studying physicochemical processes in tautomers have turned this direction into an attractive area of research due to its numerous applications.

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Background: Prior studies, comparing anterior and posterior approaches to lumbar fusion surgery, found similar fusion rates and clinical outcomes, but are limited by sample size. Further evaluation of the postoperative complications of each approach is necessary.

Methods: The MSpine database by PearlDiver was queried using ICD-9, ICD-10, and CPT codes to identify patients who had undergone single-level anterior or posterior lumbar interbody fusion surgery.

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Introduction And Methods: Based on the limited research focusing on the severity of cognitive deterioration in schizophrenia with preceding toxoplasmosis, we sampled 89 demographically matched paranoid schizophrenia patients (mean age 38.97 years) with (n = 42) and without (n = 47) seroprevalence of IgG type anti antibodies as marker of past infection. They underwent examination of verbal memory (10 words Luria test), logical memory and visual memory (BVRT), processing speed (TMT-A/DSST) and executive functions (TMT-B/verbal fluency).

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Article Synopsis
  • Researchers are investigating the effectiveness of near-infrared photosensitizers (PS) derived from synthetic bacteriochlorin to treat large cancer tumors, specifically focusing on A549 human lung cancer cells.
  • The study employs various immunocytochemical and morphological methods to analyze how these PS affect cancer cell behavior, including inducing cell death (necrosis and apoptosis) and reducing cancer cell proliferation.
  • Findings reveal that tetracationic and octacationic PS exhibit significant phototoxicity against A549 cells, with effective concentrations notably lower under light than in the dark, suggesting these compounds could be promising for enhancing photodynamic therapy outcomes.
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Article Synopsis
  • Antimicrobial photodynamic therapy (aPDT) uses light-activated compounds to target and kill drug-resistant bacteria, particularly in aquaculture settings.
  • Two clinical isolates of Gram-negative bacteria were tested: one resistant (R) and one sensitive (S) to treatment, impacting fish farming significantly due to antibiotic ineffectiveness.
  • The study evaluated different forms of palladium phthalocyanines and zinc phthalocyanine, with promising results suggesting aPDT as a viable alternative to traditional antibiotics for controlling harmful pathogens.
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The antimicrobial multidrug resistance (AMR) of pathogenic bacteria towards currently used antibiotics has a remarkable impact on the quality and prolongation of human lives. An effective strategy to fight AMR is the method PhotoDynamic Therapy (PDT). PDT is based on a joint action of a photosensitizer, oxygen, and light within a specific spectrum.

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A novel rotary switch, overcoming the disadvantages of hydrazone based switches with competitive proton acceptor sub-rotors, has been designed. The new compound contains a pyridyl ring and a COOH group as sub-rotors, which provides engagement of the pyridyl nitrogen atom and leads to the existence of a single isomer in the ground state. The availability of acidic functionality in the rotor creates conditions for excited state intramolecular proton transfer (ESIPT), which exhibits anti-Kasha behavior.

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Fluorescent and computational methods were used to elucidate the binding expedient of 2-carbamido-1,3-indandione (CAID) tautomers to nucleotides. The dependence of the fluorescence emission of CAID loaded nucleic acids sequences to compound concentration, temperature and time variation was investigated. It was found that the subject compound binds to nucleic acids but does not intercalate.

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Background: Quinazolines 1 to 6, with an aromatic or aryl-vinyl substituent in position 2 are selected with the aim to compare their structures and biological activity. The selection includes a natural alkaloid, schizocommunin, and the synthetic 2-(2'-quinolyl)-3H-quinazolin-4-one, known to interact with guanine-quadruplex dependent enzymes, respectively telomerase and topoisomerase.

Methods: Breast cancer cells of the MDA cell line have been used to study the bioactivity of the tested compounds by the method of Comet Assay and FACS analyses.

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Article Synopsis
  • The process of immobilizing proteins on a surface plasmon resonance (SPR) sensor can cause loss of their bioactivity when they come into contact with untreated metal surfaces.
  • Using a complex immobilization matrix can help, but it can compromise the sensor's selectivity and sensitivity.
  • This study explores the use of the matrix-assisted pulsed laser evaporation (MAPLE) method for directly immobilizing heme proteins (hemoglobin and myoglobin) on a SPR transducer, preserving their bioactivity, and demonstrates the structural integrity of the immobilized proteins through various analytical techniques.
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Abiotic synthesis of nucleobases and amino acids is of critical importance as it sheds light on potential prebiotic chemical reactions. During thermal decomposition of formamide in vacuum conditions, purine, cytosine, adenine, hypoxanthine, uracil, pterin, urea, urocanic acid, glycine, alanine and norvaline were detected. The compounds were obtained without catalyst by heating at 100-180 °C or microwave heating of formamide.

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The development of ionic liquids based on active pharmaceutical ingredients (API-ILs) is a possible solution to some of the problems of solid and/or hydrophobic drugs such as low solubility and bioavailability, polymorphism and an alternative route of administration could be suggested as compared to the classical drug. Here, we report for the first time the synthesis and detailed characterization of a series of ILs containing a cation amino acid esters and anion ketoprofen (KETO-ILs). The affinity and the binding mode of the KETO-ILs to bovine serum albumin (BSA) were assessed using fluorescence spectroscopy.

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Using an original model of stress-induced colon adenocarcinoma, we uncover atypical vasorelaxation effects of a mucosa injection of epinephrine assessed by laser speckle contrast imaging and a significant increase of fluorescent intensity of 5-ALA/PpIX from malignant colon tissues by a mucosa injection of nitroglycerine. We clearly demonstrate a high activity of adrenergic and nitrergic mechanisms underlying this phenomenon and discuss their application in improving of optical approaches for effective diagnosis of gastrointestinal cancer.

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The photodynamic impact of water-soluble zwitterionic zinc phthalocyanines (ZnPc1-4) was studied on pathogenic bacterial strains after specific light exposure (LED 665 nm). The structural differences between the studied ZnPc1-4 are in the positions and the numbers of substitution groups as well as in the bridging atoms (sulfur or oxygen) between substituents and macrocycle. The three peripherally substituted compounds (ZnPc1-3) are tetra-2-(N-propanesulfonic acid)oxypyridine (ZnPc1), tetra-2-(N-propanesulfonic acid)mercaptopyridine (ZnPc2), and octa-substituted 2-(N-propanesulfonic acid)mercaptopyridine (ZnPc3).

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Photodynamic inactivation (PDI) has been featured as an effective strategy in the treatment of acute drug-resistant infections. The efficiency of PDI was evaluated against three periodontal pathogenic bacteria that were tested as drug-resistant strains. In vitro studies were performed with four water-soluble cationic Zn(II) phthalocyanines (ZnPc1-4) and irradiation of a specific light source (light-emitting diode, 665 nm) with three doses (15, 36 and 60 J/cm2).

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