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result(s) for
"Najdenski, Hristo Miladinov"
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Sensitivity of Loop-Mediated Isothermal Amplification in Comparison to Digital Droplet PCR for Identification of Yersinia pseudotuberculosis in Raw Goat Milk
by
Zaharieva, Maya Margaritova
,
Kim, Tanya Chan
,
Najdenski, Hristo Miladinov
in
Colorimetry
,
Comparative analysis
,
Deoxyribonucleic acid
2026
According to the EFSA Report on Zoonoses (2024), yersiniosis was classified as the fourth most commonly reported zoonosis in humans in 2023, with a 13.5% increase in yersiniosis infections compared to 2022. In 2024, the findings were consistent with the 2020–2023 trend. Isolation and identification of enteropathogenic Yersinia is difficult and time consuming, especially when examining food and environmental samples. Among them, Y. pseudoturbeculosis poses a challenge due to the lack of a single selective medium for all bioserotypes. Therefore, faster methods for the detection of Yersinia spp. need to be implemented into the praxis. Rapid identification of pathogens in food or at the time and location of the epidemiological outbreak (point-of-care testing) enables either prevention of the outbreak or early stage diagnosis and prompt decisions. The loop-mediated isothermal amplification (LAMP) is increasingly coming to scientists’ attention as a robust and rapid methodology for pathogen detection in laboratories with limited resources and equipment. The aim of current study is to evaluate, for the first time, the sensitivity of the LAMP protocol based on colorimetric detection in the visible spectrum in comparison with that of the digital droplet PCR (ddPCR). For this aim, a series of decimal logarithmic dilutions of the pathogen Y. pseudotuberculosis in artificially contaminated raw goat milk was used. One commercial LAMP kit with two different dyes (one dsDNA-binding and one Mg2+-sensitive) was compared to the sensitivity of the detection to ddPCR. The results obtained revealed a high sensitivity of the kit for detection of DNA isolated from artificially contaminated milk samples in the following range: visible detection based on visible color change—3.1 × 104 mL (violet dye) and 3.4 × 103/mL (blue dye); detection with gel electrophoresis—2.0 × 101/mL (violet dye) and 3.4 × 102/mL (blue dye). The enumeration of the DNA copies in the same samples was performed with ddPCR, with a detection limit of 2.0 × 101/mL. Our results indicate the potential and the possible applicability of the LAMP method for rapid and sensitive visual detection of Y. pseudotuberculosis in raw goat milk. The presented ddPCR protocol can be used for highly sensitive identification and enumeration of Y. pseudtuberculosis in raw goat milk. In conclusion, the conducted comparison is of importance for future implementation of LAMP protocols for on-field analysis near the sampling site and point-of-care or laboratory diagnostics of Y. pseudtuberculosis after the successful validation procedure of an appropriate LAMP protocol.
Journal Article
Micellar curcumin improves the antibacterial activity of the alkylphosphocholines erufosine and miltefosine against pathogenic Staphyloccocus aureus strains
by
Dimitrova, Lyudmila
,
Momchilova, Milena
,
Mihaylov Konstantinov, Spiro
in
Adenomatous polyposis coli
,
Antibacterial activity
,
antibacterial properties
2019
In the light of the emerging bacterial resistance to broad-spectrum antibiotics, the search for new antibacterial therapeutics and drug combinations is one of the most challenging topics nowadays. In the present study, we investigated for the first time the antibacterial and biofilm inhibitory effects of the third generation anticancer alkylphosphocholine (APC) erufosine against pathogenic Staphylococcus aureus strains in comparison to the prototype of this pharmacological class of drugs, miltefosine. We also searched for synergistic antibacterial combinations between both APCs and curcumin incorporated in copolymeric micelles based on Pluronic® P123 or a mixture of Pluronic
®
P123 and Pluronic
®
F127 (P123/F127). The obtained quantitative redox-activity experimental data and drug-drug interactions were evaluated by using mathematical models in the MAPLE software. Similar to miltefosine, erufosine showed a moderate bacteriostatic effect in clinically relevant concentrations (50 ÷ 60 µmol/L) and inhibited the redox activity of the treated bacteria up to 90% at minimal inhibitory concentrations. The effect of both APCs towards methicillin resistant staphylococci was enhanced by combinations with P123/F127 micellar CRM at a ratio of 1:1. Erufosine showed a stronger median biofilm inhibition at lower concentrations (MBIC
50
= 1.87 µmol/L) than miltefosine (MBIC
50
= 6.0 µmol/L) and curcumin (MBIC
50
= 24.84 µmol/L) as demonstrated by quantification of biofilm-bound bacteria. In conclusion, the estimated antibacterial activity of erufosine widens the spectrum of its useful pharmacological effects, which is important for its clinical development. The established synergistic and additive drug combinations could be beneficial for the application of both APCs in cancer therapy, since numerous malignancies are accompanied by bacterial infections.
Journal Article
Photodynamic Inactivation of Bovine Coronavirus with the Photosensitizer Toluidine Blue O
by
Ilieva, Yana
,
Karamichali, Eirini
,
Kussovski, Vesselin
in
Adenoviruses
,
Animals
,
Antiviral activity
2023
Coronaviruses (CoVs) belong to the group of enveloped positive-sense single-strand RNA viruses and are causative agents of respiratory, gastro-intestinal, and central nervous systems diseases in many host species, i.e., birds, mammals, and humans. Beta-CoVs revealed a great potential to cross the barrier between species by causing three epidemics/pandemics among humans in the 21st century. Considering the urgent need for powerful antiviral agents for decontamination, prevention, and treatment of BCoV infections, we turned our attention to the possibility of photodynamic inactivation with photosensitizers in combination with light irradiation. In the present study, we evaluated, for the first time, the antiviral activity of toluidine blue O (TBO) against Beta-coronavirus 1 (BCoV) in comparison to methylene blue (MB). First, we determined the in vitro cytotoxicity of MB and TBO on the Madin–Darby bovine kidney (MDBK) cell line with ISO10993-5/Annex C. Thereafter, BCoV was propagated in MDBK cells, and the virus titer was measured with digital droplet PCR, TCID50 assay and plaque assay. The antiviral activity of non-toxic concentrations of TBO was estimated using the direct inactivation approach. All effects were calculated in MAPLE 15® mathematical software by developing programs for non-linear modeling and response surface analysis. The median inhibitory concentration (IC50) of TBO after 72 h of incubation in MDBK cells was 0.85 µM. The antiviral activity of TBO after the direct inactivation of BCoV (MOI = 1) was significantly stronger than that of MB. The median effective concentration (EC50) of TBO was 0.005 µM. The cytopathic effect decreased in a concentration-dependent manner, from 0.0025 to 0.01 µM, and disappeared fully at concentrations between 0.02 and 0.3 µM of TBO. The number of virus particles also decreased, depending on the concentration applied, as proven by ddPCR analysis. In conclusion, TBO exhibits significant potential for direct inactivation of BCoV in vitro, with a very high selectivity index, and should be subjected to further investigation, aiming at its application in veterinary and/or human medical practice.
Journal Article
System Analysis Theory Applied for Development of Microalgae Processes and Photobioreactors in the Frame of Integral Biorefinery Concept
by
Kroumov, Alexander
,
Najdenski, Hristo
,
Zaharieva, Maya
in
Algae
,
Antiviral drugs
,
biorefinery concept
2024
Microalgae technology involves many steps of unit operations and is connected with global warming and pandemic problems because of the unique features of algal cells. Studying sophisticated systems cannot be without special mathematical tools and approaches that combine knowledge from many research areas. The system analysis theory applied in biotechnology with great success can be applied by principles of analogy to microalgae cultivation of cells in CO2 fixation from flue gases in innovative closed photobioreactors (PBRs) where the products of biomass can have performed antimicrobial, anticancer, antiviral and other activities by challenging chemical agents. Recently, a multifunctional algology laboratory was created at the Stephan Angeloff Institute of Microbiology by applying knowledge in state of the art. The goal of this work was to summarize the 40 years of experience of the authors in this area and to show how this was realized by innovative engineering solutions for studying and developing the microalgae system. Special attention was paid to the development of hybrid, innovative PBRs with the aim of fully revealing the potential of microalgae strains not only for the complete absorption of CO2 from flue gases but also for the synthesis of high-value products (HVP) with antimicrobial, antiviral and anticancer activity.
Journal Article
Synergistic Antibacterial Effect of Mucus Fraction from Cornu aspersum and Cirpofloxacin Against Pathogenic Bacteria Isolated from Wounds of Diabetic Patients
by
Dolashki, Aleksandar
,
Kaleva, Mila Dobromirova
,
Velkova, Lyudmila
in
Amputation
,
Analysis
,
Antibacterial activity
2025
Background/Objectives: The treatment of diabetic foot ulcers (DFU) is a challenging medical problem of extreme clinical and social importance, as a consequence of the emerging antibiotic resistance and decreased quality of life of diabetic patients due to impaired wound healing. One of the current trends in world science is the search for biologically active substances derived from living organisms. Biologically active peptides from snail mucus attract considerable scientific interest because of their pleiotropic pharmacological properties. The aim of our study was to evaluate the activity of a combination between a snail mucus protein fraction (MW > 20 kDa) obtained from the garden snail Cornu aspersum and the clinically applied antibacterial chemotherapeutic ciprofloxacin on pathogenic bacterial strains isolated from DFU. Results: The test bacterial strains were characterized as multidrug resistant. The combination between ciprofloxacin and the snail mucus fraction of interest led to additive or synergistic effects depending on the test strain. The mucus fraction exerted a well-pronounced wound-healing effect and no cytotoxicity on normal human fibroblasts and keratinocytes. Methods: The snail mucus was obtained by a patented technology (BG Utility model 2097/2015) and its electrophoretic profile was presented by SDS-PAGE. The bacterial strains were identified and tested for antimicrobial susceptibility (BD Phoenix M50 and Kirby–Bauer assay). The in vitro cytotoxicity of the mucus was evaluated by ISO 10995-5. The antimicrobial activity and combination effects were tested through ISO 20776/1 and the Checkerboard assay. Conclusions: The obtained results are promising and open new horizons for the development of novel combination treatment schemas for healing of infected DFU.
Journal Article
Complex Analysis of New Unique Human Society Life in Eight Coordinate System
by
Kroumov, Alexander
,
Trigueros, Daniela
,
Módenes, Aparecido
in
chronically ill people
,
coronavirus
,
Coronaviruses
2021
The article presents deep and complex analysis based on the changes of life of human society during the COVID-19 pandemic. The World as never before has a global common enemy and everyone is in danger doesn’t matter where he lives and what is the occupation. The life new dimensions are considered as an 8-coordinate system where the new 4 coordinates – coronavirus, “virus” of poverty, “virus” of chronically ill people and scientists as new leading factor of the world. It means, a simple solution for prevention and regulation of pandemic doesn’t exist. Countries and outbreaks are represented by 4 everlasting coordinates – three for space and for time measurement. The life of human society is conditionally divided of 4 hierarchic levels. Interactions between them have to be studied by scientists from all areas in order to win this word challenge where all humans are on the same side of the barricade. The presented analysis could be extremely useful for explanation the errors made by leaders and to show them that the new reality requires relevant and effective decisions based on scientific complex analyzes and taking into account the four hierarchic levels of knowledge.
Journal Article