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Sustainable varroa mite (Varroa destructor) control in field conditions
Aleš Gregorc, Ivo Planinc, 2022, original scientific article

Abstract: Experiments assessed the comparative efficacy of oxalic acid solution (OA) and combination of formic acid (FA) evaporation and trickling OA to control the honey bee mite, Varroa destructor, at two apiary locations. Queen caging, consecutive OA treatments of broodless colonies, or combined treatments using OA and FA in colonies with brood increased mite mortality (P < 0.05) in comparison to the pre-treatment period. FA application in colonies with brood in September and October resulted in an average mite mortality of 18% in the first apiary and subsequent FA applications in the same period in the second apiary killed, on average, 73% and 71% of mites; respectively. OA treatment of broodless colonies after queen caging at two apiaries resulted in 18% and 47% mite mortality. Caging the queens and OA treatments in broodless colonies or subsequently use consecutive OA or FA treatments ensure adequate mite reduction before wintering the colonies. Synergistic control methods of Varroa mites using OA and FA along with queen caging is discussed.
Keywords: beekeeping, mite control, oxalic acid, formic acid, queen caging
Published in DKUM: 10.07.2024; Views: 44; Downloads: 2
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Modeling the amino acid effect on glucagon secretion from pancreatic alpha cells
Jan Zmazek, Vladimir Grubelnik, Rene Markovič, Marko Marhl, 2022, original scientific article

Abstract: Type 2 Diabetes Mellitus (T2DM) is a burdensome problem in modern society, and intensive research is focused on better understanding the underlying cellular mechanisms of hormone secretion for blood glucose regulation. T2DM is a bi-hormonal disease, and in addition to 100 years of increasing knowledge about the importance of insulin, the second hormone glucagon, secreted by pancreatic alpha cells, is becoming increasingly important. We have developed a mathematical model for glucagon secretion that incorporates all major metabolic processes of glucose, fatty acids, and glutamine as the most abundant postprandial amino acid in blood. In addition, we consider cAMP signaling in alpha cells. The model predictions quantitatively estimate the relative importance of specific metabolic and signaling pathways and particularly emphasize the important role of glutamine in promoting glucagon secretion, which is in good agreement with known experimental data.
Keywords: diabetes, hormone secretion, glucose, amino acid, cAMP
Published in DKUM: 21.05.2024; Views: 137; Downloads: 8
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Antibacterial effect of topically administered tranexamic acid in large joint arthroplasty
Urban Slokar, Simon Kovač, Andrej Cör, Katja Šuster, 2023, original scientific article

Abstract: Tranexamic acid (TXA) is a synthetic derivative of the amino acid lysine and is commonly used as an antifibrinolytic agent in large joint surgery, such as knee arthroplasty, to minimize blood loss and its associated complications. Some studies have suggested that perioperative intravenous TXA application lowers the incidence of postoperative infections after hip and knee arthroplasty. While its effects on bacteria are not its primary purpose, more research is needed further to elucidate the extent of TXA’s impact on bacterial inhibition and its clinical relevance. In order to determine possible inhibitory effects, 22 clinically relevant bacterial strains were exposed to different TXA concentrations. Two different assays were performed: a microdilution assay with traditional endpoint measurements and a kinetic growth assay for a time-dependent susceptibility assessment. With the microdilution technique, a growth inhibitory effect became evident at higher TXA concentrations (50 and 100 mg/mL) on eight tested bacterial strains, of which four demonstrated absence of growth at 100 mg/mL, suggesting minimal inhibitory concentration. However, the kinetic growth assay revealed more specific TXA-induced dynamic changes in the bacterial growth of all tested bacterial strains. This study showed that TXA affects the growth dynamics of bacteria by altering their lag phase duration, exponential growth rate, and population density and may contribute to the prevention of implant-associated infections.
Keywords: tranexamic acid, bacterial growth, antimicrobial effect, topical administration, arthroplasty
Published in DKUM: 19.04.2024; Views: 110; Downloads: 5
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Incorporation of Biologically Active Ingredient Gallic Acid into Nano-scale Lipid Vesicles
Nika Kučuk, Mateja Primožič, Željko Knez, Maja Leitgeb, 2023, original scientific article

Keywords: nano-scale, gallic acid, lipid vesicle
Published in DKUM: 18.04.2024; Views: 106; Downloads: 4
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From nature to lab : sustainable bacterial cellulose production and modification with synthetic biology
Vid Potočnik, Selestina Gorgieva, Janja Trček, 2023, review article

Abstract: Bacterial cellulose (BC) is a macromolecule with versatile applications in medicine, pharmacy, biotechnology, cosmetology, food and food packaging, ecology, and electronics. Although many bacteria synthesize BC, the most efficient BC producers are certain species of the genera Komagataeibacter and Novacetimonas. These are also food-grade bacteria, simplifying their utilization at industrial facilities. The basic principles of BC synthesis are known from studies of Komagataeibacter xylinus, which became a model species for studying BC at genetic and molecular levels. Cellulose can also be of plant origin, but BC surpasses its purity. Moreover, the laboratory production of BC enables in situ modification into functionalized material with incorporated molecules during its synthesis. The possibility of growing Komagataeibacter and Novacetimonas species on various organic substrates and agricultural and food waste compounds also follows the green and sustainable economy principles. Further intervention into BC synthesis was enabled by genetic engineering tools, subsequently directing it into the field of synthetic biology. This review paper presents the development of the fascinating field of BC synthesis at the molecular level, seeking sustainable ways for its production and its applications towards genetic modifications of bacterial strains for producing novel types of living biomaterials using the flexible metabolic machinery of bacteria.
Keywords: acetic acid bacteria, bacterial cellulose, sustainable production, agricultural waste, food waste, genetic engineering, synthetic biology, biomaterial, Komagataeibacter, Novacetimonas
Published in DKUM: 28.03.2024; Views: 202; Downloads: 23
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Numerical analysis of a transtibial prosthesis socket using 3D-Printed Bio-Based PLA
Vasja Plesec, Jani Humar, Polona Dobnik-Dubrovski, Gregor Harih, 2023, original scientific article

Abstract: Lower-limb prosthesis design and manufacturing still rely mostly on the workshop process of trial-and-error using expensive unrecyclable composite materials, resulting in time-consuming, material-wasting, and, ultimately, expensive prostheses. Therefore, we investigated the possibility of utilizing Fused Deposition Modeling 3D-printing technology with inexpensive bio-based and bio-degradable Polylactic Acid (PLA) material for prosthesis socket development and manufacturing. The safety and stability of the proposed 3D-printed PLA socket were analyzed using a recently developed generic transtibial numeric model, with boundary conditions of donning and newly developed realistic gait cycle phases of a heel strike and forefoot loading according to ISO 10328. The material properties of the 3D-printed PLA were determined using uniaxial tensile and compression tests on transverse and longitudinal samples. Numerical simulations with all boundary conditions were performed for the 3D-printed PLA and traditional polystyrene check and definitive composite socket. The results showed that the 3D-printed PLA socket withstands the occurring von-Mises stresses of 5.4 MPa and 10.8 MPa under heel strike and push-off gait conditions, respectively. Furthermore, the maximum deformations observed in the 3D-printed PLA socket of 0.74 mm and 2.66 mm were similar to the check socket deformations of 0.67 mm and 2.52 mm during heel strike and push-off, respectively, hence providing the same stability for the amputees. We have shown that an inexpensive, bio-based, and bio-degradable PLA material can be considered for manufacturing the lower-limb prosthesis, resulting in an environmentally friendly and inexpensive solution.
Keywords: 3D printing, bio-based, polylactic acid, PLA, prosthesis, prosthesis socket, numerical model, finite element method
Published in DKUM: 14.03.2024; Views: 157; Downloads: 24
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Hybrid polylactic-acid–pectin aerogels : synthesis, structural properties, and drug release
Gabrijela Horvat, Klara Žvab, Željko Knez, Zoran Novak, 2023, original scientific article

Abstract: Wound-dressing materials often include other materials stimulating wound healing. This research describes the first formulation of biodegradable hybrid aerogels composed of polylactic acid and pectin. The prepared hybrid material showed a highly porous structure with a surface area of 166 +/- 22.6 m(2)center dot g(-1). The addition of polylactic acid may have decreased the surface area of the pure pectin aerogel, but it improved the stability of the material in simulated body fluid (SBF). The pure pectin aerogel showed a high swelling and degradation ratio after 3 h. The addition of the polylactic acid prolonged its stability in the simulated body fluid from 24 h to more than one week, depending on the amount of polylactic acid. Biodegradable aerogels were loaded with indomethacin and diclofenac sodium as model drugs. The entrapment efficiencies were 63.4% and 62.6% for indomethacin and diclofenac sodium, respectively. Dissolution of both drugs was prolonged up to 2 days. Finally, sodium percarbonate and calcium peroxide were incorporated into the bioaerogels as chemical oxygen sources, to evaluate oxygen generation for potential wound healing applications.
Keywords: hybrid aerogels, bioaerogel, pectin, polylactic acid, wound healing
Published in DKUM: 20.02.2024; Views: 312; Downloads: 16
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