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341 results on '"Majewska, M."'

1. Multiple polar and non-polar nematic phases

Author

Brown, S., Cruickshank, E., Storey, J. M. D., Imrie, C. T., Pociecha, D., Majewska, M., Makal, A., and Gorecka, E.

Subjects
Condensed Matter - Soft Condensed Matter
Abstract

Liquid crystal materials exhibiting up to three nematic phases are reported. Dielectric response measurements show that while the lower temperature nematic phase has ferroelectric order and the highest temperature nematic phase is apolar, the intermediate phase has local antiferroelectric order. The modification of the molecular structure by increasing the number of lateral fluorine substituents leads to one of the materials showing a direct isotropic-ferronematic phase transition.

Published
2021

3. Comparing the chemical composition of lesser duckweed (Lemna minor L.) grown in natural and laboratory settings.

Author

Miltko, R., Majewska, M. P., Wojtak, W., Białek, M., Kowalik, B., and Czauderna, M.

Subjects
ESSENTIAL amino acids, LEMNA minor, AMINO acids, G proteins, FATTY acids
Abstract

The aim of this study was to compare the chemical composition of lesser duckweed (Lemna minor L.) obtained from the natural environment and cultured under laboratory conditions. In the fi rst variant, lesser duckweed was  collected from a natural pond (LDN). Subsequently, the plants were cleaned of other aquatic fl ora and fauna, dried, and ground. In the second variant, lesser  duckweed was cultured in an aquarium (LDC) illuminated from 04:00 to 24:00. The water temperature was 25 °C and the pH was maintained in the range of 6.5–7.3. The content of crude protein, fat, and fi bre was similar in LDN and LDC,  but the proportion of crude ash was higher in LDC. The content of total amino acids was 95.70 and 68.71 g/100 g crude protein in LDC and LDN, respectively. The concentrations of essential amino acids and nonessential amino acids were 43.75 and 51.96 g/100 g crude protein in LDC, respectively, and 32.10 and 36.61 g/100 g crude protein in LDN, respectively. Palmitic and stearic acids were found in higher quantities in LDN than LDC, whereas the oleic acid content was three-fold higher  in LDN compared to LDC. Moreover,  linoleic and α-linolenic  acid concentrations were higher in LDN than LDC. Mineral analysis revealed elevated levels of Ca, Na, and Zn, while P and Mg levels were lower in LDC. Additionally, the levels of δ-, γ-tocopherols and α-tocotrienol were found to be  higher in LDC, while δ- and γ-tocotrienols in LDC were below detectable limits.  So, the  signifi cant  infl uence of growth  conditions on the nutrient  composition  of L. minor was shown. Optimizing growth conditions is pivotal for enhancing lesser duckweed production. It seems that L. minor can be a valuable source of essential nutrients and could serve as a supplementary food source for both domestic animals and humans. Nonetheless, anti-nutritional components, including toxic metals, should be monitored. [ABSTRACT FROM AUTHOR]

Published
2024
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9. Inhibition of Amyloid β-Induced Lipid Membrane Permeation and Amyloid β Aggregation by K162

Author

Mrdenovic, D., Majewska, M., Pieta, I.S., Kutner, W., Lipkowski, J., and Pieta, P.

Subjects
amyloid, AFM, lipid membrane permeation, K162
Abstract

Alzheimer’s disease (AD) is characterized by progressive neurodegeneration associated with amyloid β (Aβ) peptide aggregation. The aggregation of Aβ monomers (AβMs) leads to the formation of Aβ oligomers (AβOs), the neurotoxic Aβ form, capable of permeating the cell membrane. Here, we investigated the effect of a fluorene-based active drug candidate, named K162, on both Aβ aggregation and AβO toxicity toward the bilayer lipid membrane (BLM). Electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM), and molecular dynamics (MD) were employed to show that K162 inhibits AβOs-induced BLM permeation, thus preserving BLM integrity. In the presence of K162, only shallow defects on the BLM surface were formed. Apparently, K162 modifies Aβ aggregation by bypassing the formation of toxic AβOs, and only nontoxic AβMs, dimers (AβDs), and fibrils (AβFs) are produced. Unlike other Aβ toxicity inhibitors, K162 preserves neurologically beneficial AβMs. This unique K162 inhibition mechanism provides an alternative AD therapeutic strategy that could be explored in the future. Natural Sciences and Engineering Research Council of Canada (NSERC),Polish National Science Centre, European Union's Horizon 2020 research and innovation program under the Marie SkłodowskaCurie grant

Published
2021

12. Size-dependent interaction of amyloid β oligomers with brain total lipid extract bilayer – fibrillation vs. membrane destruction

Author

Mrdenovic, D., Majewska, M., Pieta, I.S., Kutner, W., Lipkowski, J., Pieta, P., and Bernatowicz, P.

Subjects
Size-Dependent, Amyloid b, AFM
Abstract

Amyloid β, Aβ(1–42), is a component of senile plaques present in the brain of Alzheimer’s disease patients and one of the main suspects responsible for pathological consequences of the disease. Herein, we directly visualize the Aβ activity toward a brain-like model membrane and demonstrate that this activity strongly depends on the Aβ oligomer size. PeakForce quantitative nanomechanical mapping mode of atomic force microscopy imaging revealed that the interaction of large-size (LS) Aβ oligomers, corresponding to high-molecular-weight Aβ oligomers, with the brain total lipid extract (BTLE) membrane resulted in accelerated Aβ fibrillogenesis on the membrane surface. Importantly, the fibrillogenesis did not affect integrity of the membrane. In contrast, small-size (SS) Aβ oligomers, corresponding to low-molecular-weight Aβ oligomers, created pores and then disintegrated the BTLE membrane. Both forms of the Aβ oligomers changed nanomechanical properties of the membrane by decreasing its Young’s modulus by ∼45%. Our results demonstrated that both forms of Aβ oligomers induce the neurotoxic effect on the brain cells but their action toward the membrane differs significantly. Polish National Science Centre, the European Union Horizon 2020 Research and Innovation Programme under the Marie SkłodowskaCurie grant agreement, the Polish Ministry of Science and Higher Education for the implementation of an international co-financed project

Published
2019

18. The effect of commercial enzyme preparation-assisted maceration on the yield, quality, and bioactivity of essential oil from waste carrot seeds (Daucus carota L.)

Author

Śmigielski, K. B., Majewska, M., Kunicka-Styczyńska, A., Gruska, R., and Stańczyk, Ł.

Subjects
Preparación enzimática, Nutrition. Foods and food supply, food and beverages, lcsh:TX341-641, enzyme preparation, essential oil, Essential oil, Enzyme preparation, Método Taguchi, taguchi method, Aceite esencial, Carrot, Zanahoria, Taguchi method, TX341-641, lcsh:Nutrition. Foods and food supply, carrot
Abstract

Eight enzyme preparations were screened with a view to maximizing the yield of carrot seed essential oil. Three of the eight enzyme preparations investigated, lipase from Mucor circinelloides, XPect® pectinase, and Esperase® protease, significantly influenced the amount of essential oil obtained, with Esperase® being the most effective. The Taguchi method was applied to optimize the processing conditions for the Esperase® protease. Under the optimum conditions, the essential oil yield increased by approximately 48%. The main constituent compounds in the oil are: carotol (OeA: 40.80%–OeB: 46.17%), daucol (OeA: 7.35%–OeB: 6.22%), sabinene (OeA: 5.12%–OeB: 6.13%), alpha-pinene (OeA: 4.24%–OeB: 5.11%) and geranyl acetate (OeA: 4.50%–OeB: 3.68%). As compared to the control sample, the essential oil obtained from enzyme-pretreated carrot seeds has the same biological activity against Bacillus subtilis and Candida sp., lower activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, and higher activity against Aspergillus niger and Penicillium expansum.Ocho preparados enzimáticos fueron seleccionados con el fin de maximizar el rendimiento de aceites esenciales de semillas de zanahoria. Tres de los ocho preparados de las enzimas investigadas, lipasa de Mucor circinelloides, Xpect® pectinasa y Esperase® proteasa, influyeron de manera significativa sobre la cantidad de aceite esencial obtenido, siendo Esperase® el más eficaz. El método de Taguchi se aplicó para optimizar las condiciones del procesamiento para esta última. Bajo las condiciones óptimas, el rendimiento de los aceite esenciales aumentó aproximadamente un 48%. Los principales compuestos constituyentes del aceite son: carotol (OEA: 40.80%–OeB: 46,17%), ducol (OEA: 7,35%–OeB: 6,22%), sabineno (OEA: 5,12%–OeB: 6,13%), alfa-pineno (OEA: 4,24%– OeB: 5,11%) y acetato de geranilo (OEA: 4,50%–OeB: 3,68%). En comparación con la muestra control, el aceite esencial obtenido a partir de las semillas de zanahoria mediante enzima-pretratada tiene la misma actividad biológica frente a Bacillus subtilis y Candida sp., menor actividad frente a Staphylococcus aureus, Escherichia coli, y Pseudomonas aeruginosa, y una mayor actividad contra Aspergillus niger y Penicillium expansum.

Published
2014
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24. Effect of blanching and cooking on antioxidant capacity of cultivated edible mushrooms: A comparative study.

Author

Radzki, W., Sławińska, A., Jabłońska-Ryś, E., and Michalak-Majewska, M.

Subjects
BLEACHING (Chemistry), ANTIOXIDANTS, EDIBLE mushrooms, COMPARATIVE studies, COOKING
Abstract

Three common species of cultivated edible mushrooms were analyzed in terms of their antioxidant capacity and total phenolics content. Fruiting bodies of Agaricus bisporus, Pleurotus ostreatus and Lentinula edodes were subjected to blanching in a citric acid solution for five minutes and boiling in water for fifteen minutes. Both ethanolic and water extracts were obtained from the mushrooms and their antioxidant abilities were evaluated with FRAP and DPPH assays. The content of total phenolic compounds in the extracts was determined. Among the three analyzed species, A. bisporus possessed the highest antioxidant capacity and total phenolics content, whereas L. edodes had the lowest. In general, the processing resulted in the decrease of the antioxidant activity and the species which was the most vulnerable to the hydrothermal treatments was P. ostreatus. [ABSTRACT FROM AUTHOR]

Published
2016

25. Arbuscular mycorrhiza and fungal root endophytes of weeds in an altitudinal gradient in the Pamir Alai Mountains of Central Asia.

Author

Zubek, S., Nobis, M., Błaszkowski, J., Nowak, A., Majewska, M. L., and Bąba, W.

Subjects
VESICULAR-arbuscular mycorrhizas, ENDOPHYTES, WEEDS, GALIUM (Plant genus)
Abstract

Arbuscular mycorrhiza and fungal root endophytes of three weeds,Galium tricornutum,Lycopsis orientalisandScandix pecten-veneris, were studied in an altitudinal gradient of the Pamir Alai Mountains. Colonisation by arbuscular mycorrhizal fungi (AMF) was found in all species. Only in the case ofG. tricornutumwas there a rise in mycorrhizal parameters values found for the medium altitude range. Similar tendencies were observed in the case of the AMF colonisation potential assessment. This suggests that plant species' identity, dependency on symbiosis and interactions with soil properties determine root colonisation and the abundance of AMF in soils at the elevations in question. Four AMF species,Claroideoglomus claroideum,Funneliformis mosseae,Scutellospora dipurpurescensandSeptoglomus constrictum, were isolated from trap cultures established on soil taken from under the weeds. Dark septate endophytes (DSE) accompanied the AMF in the roots ofG. tricornutumandS. pecten-veneris; however, they were neither frequently occurring nor abundant. The sporangia ofOlpidiumspp. were observed with low frequency occurrence inG. tricornutumandS. pecten-venerisand more often in the roots ofL.orientalis. However, in both cases, they were low in abundance. No differences were found for the presence of DSE andOlpidiumin the altitudinal gradient. [ABSTRACT FROM AUTHOR]

Published
2016
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35. Microbial Activity -- Factor Increasing Retention of Cd Added to Soil.

Author

Majewska, M., Kurek, E., and Szlachetka, D.

Abstract

The effects of microbial activity on speciation of Cd added to soil (10 mg⋅kg-1) in immobilized form or as a water solution of CdCl2 were investigated. Cadmium was immobilized in vitro by humic acids, bacterial or fungal biomass, or by bentonite. There was no inhibition of bacterial or fungal growth in the soil supplemented with Cd. An increase in soil pH values resulted from the microbial activity. After a 42-day incubation of the soil, the percentage of Cd extractable by 0.1 M NaNO3 in the soil with microbial activity amounted, on average, to 70% of that in the autoclaved soil. At the same time, the percentage of Cd extracted by 0.1 M NaNO3 from the soil supplemented with immobilized Cd was on average 31% of that extracted from the soil supplemented with a water solution of CdCl2. The reduction of the exchangeable fraction in the soil supplemented with the metal immobilized by bacterial biomass was connected with the enrichment of the organically bound fraction whereas in the soil with an addition of Cd immobilized by fungal biomass the reduction was linked with the enrichment of the residual fraction. Cadmium was transferred from the exchangeable fraction to a fraction extracted by hydroxylamine in the soil supplemented with Cd immobilized by abiotic soil constituents but it was transferred from the residual to the exchangeable fraction in the soil enriched with CdCl2. Among other factors tested, only pH values and the time of exposure of the soil to Cd affected the amount of the exchangeable Cd fraction in the soil. [ABSTRACT FROM AUTHOR]

Published
2006

36. Prostaglandin Endoperoxide Synthase 2 (PTGS2) and Prostaglandins F2α and E2 Synthases (PGFS and PGES) Expression and Prostaglandin F2α and E2 Secretion Following Oestrogen and/or Progesterone Stimulation of the Feline Endometrium.

Author

Siemieniuch, MJ, Jursza, E, Kowalewski, MP, Majewska, M, and Skarzynski, DJ

Subjects
CYCLOOXYGENASES, GENE expression in mammals, ENDOMETRIUM, PROGESTERONE, STEROIDS, MESSENGER RNA, ARACHIDONIC acid, PSEUDOCYESIS
Abstract

Contents Sex steroids in synergy with prostaglandins (PG) are involved in the regulation of cyclic ovarian function. In this study, we investigated the mRNA expression of three genes involved in arachidonic acid (AA) metabolism and hence PG production in domestic cats: PG-endoperoxide synthase ( PTGS2), PGF2α synthase ( PGFS) and PGE2 synthase ( PGES). Feline endometria (n = 16) were collected at oestrus and mid and late phases of pseudopregnancy. In addition, the effects of E2 and/or P4 on PG secretion and gene expression on endometrial explants were studied in an in vitro culture system. Expression levels of all examined genes were up-regulated at the mid phase of pseudopregnancy. The effects of E2 and/or P4 treatment on both PG secretion and expression of the genes were observed after 12 h of culture. Expression of PGES was significantly up-regulated by E2 plus P4 at oestrus and the mid phase of pseudopregnancy and was also up-regulated by a single treatment with P4 at late pseudopregnancy (p < 0.05). Simultaneous incubation with E2 and P4 up-regulated PTGS2 gene expression at oestrus and mid-luteal phase (p < 0.05). Progesterone plus E2 significantly increased PGE2 secretion at oestrus and the mid phase of pseudopregnancy. However, treatment with E2 and/or P4 affected neither PGF2α secretion nor PGFS expression at any phase after 12 h of culture. The overall findings indicate that genes involved in PG synthesis are up-regulated at the mid phase of pseudopregnancy. An increase in PGE2 secretion and up-regulation of PGES and PTGS2 are the main responses of the endometrium to treatment with E2 and P4 at oestrus and the mid phase of pseudopregnancy in the cat. These data support the hypothesis that ovarian sex steroids via endometrial PGE2 are involved in endocrine homoeostasis, especially at oestrus and the mid, but not the late, phase of pseudopregnancy in cats. [ABSTRACT FROM AUTHOR]

Published
2013
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40. Benzodiazepines enhance the muscimol-dependent activation of phospholipase A2 in glioma C6 cells.

Author

Majewska, M D and Chuang, D M

Abstract

Glioma C6 cells were incubated with [14C]arachidonate to label membrane phospholipids. Muscimol, a selective gamma-aminobutyric acid A receptor agonist, but not (-)-baclofen, a selective gamma-aminobutyric acid B receptor agonist, stimulates [14C]arachidonate release from C6 cells as a result of hydrolysis of a small pool of phosphatidylcholine and phosphatidylethanolamine by phospholipase A2. This release is facilitated by diazepam and a number of other benzodiazepines such as flunitrazepam, medazepam and midazolam (but very little by clonazepam), although these benzodiazepines per se are inactive in causing the release. In addition to increasing the release of [14C]arachidonate, diazepam in the presence of muscimol promotes the release of [14C] prostaglandin D2. Bicuculline inhibits the action of muscimol and facilitation by diazepam. "Peripheral" benzodiazepine ligand, RO 5-4864 (4'-chlordiazepam) antagonizes the action of diazepam, whereas "central" ligand, RO 15-1788, is inactive. The release of arachidonate metabolites stimulated by muscimol and diazepam is unaffected by Cl- channel blockers, picrotoxin and pentylenetetrazol. Based on these results we propose that in glioma C6 cells (and presumably in normal glia) peripheral benzodiazepine receptor interacts functionally with gamma-aminobutyric acid A type of receptor, which appears not to be linked to picrotoxin sensitive Cl- channel, and may be linked to phospholipase A2.

Published
1985

41. Modulation by calcium of gamma-aminobutyric acid (GABA) binding to GABAA and GABAB recognition sites in rat brain. Involvement of different mechanisms.

Author

Majewska, M D and Chuang, D M

Abstract

Calcium modulates sodium-independent binding of gamma-aminobutyric acid (GABA) to GABAA and GABAB recognition sites located in synaptic membranes of rat brain. At 37 degrees the binding of [3H]GABA to the GABAB recognition site is dramatically stimulated by Ca2+ with an EC50 (half-saturation constant) of congruent to 10 microns, whereas the binding to the GABAA recognition site is only slightly, but significantly, potentiated by Ca2+ with an EC50 of congruent to 0.1-1.0 micron. The effect of calcium on GABAA recognition sites requires a temperature of 37 degrees and the presence of calmodulin. Only GABAA recognition sites are linked to benzodiazepine recognition sites, and the interaction between these sites is modulated by Ca2+ at physiological ion concentrations. When free Ca2+ in the assay medium is below 10 nM, only one population of low-affinity GABAA recognition sites can be measured; however, when free Ca2+ is at the micromolar level, or if diazepam is present, a high affinity-binding site appears in addition to the pre-existing low-affinity component. On the basis of affinity there is a single population of GABAB bindings sites, but the number of sites is about 90% greater at 37 degrees than at 4 degrees. This temperature-dependent increase in the number of GABAB recognition sites is calmodulin-independent, and data with leupeptin, hemin, and antipain suggest that this temperature-dependent increase in GABAB sites might involve the activity of Ca2+-dependent protease(s).

Published
1984

42. Interactions of noncompetitive inhibitors with nicotinic receptors in the rat brain.

Author

Takayama, H, Majewska, M D, and London, E D

Abstract

This study was performed to determine how drugs that inhibit the function of peripheral nicotinic receptors (noncompetitive inhibitors), interact with nicotinic receptors in the brain. By using [3H]MCC (methylcarbamylcholine ) as a ligand for nicotinic receptors, competition studies at a fixed concentration of radioligand and saturation studies were performed with various noncompetitive inhibitors. [3H]MCC labeled high affinity nicotinic receptor sites in the rat brain at equilibrium. The sites appeared to represent desensitized nicotinic receptors, comprising a fraction of the total pool of these receptors. At micromolar concentrations, noncompetitive inhibitors interacted distinctively with [3H]MCC binding sites. Mecamylamine behaved as an allosteric inhibitor, as it decreased the apparent density of [3H]MCC binding sites. Tetracaine had mixed allosteric/competitive properties, reducing both the density and the affinity of binding. Chlorpromazine manifested a biphasic effect, increasing receptor density at concentrations of approximately 50 to 500 microM and reducing the affinity at higher concentrations. The results suggest that noncompetitive inhibitors bind to different, but interacting sites associated with desensitized nicotinic receptors in the brain, as well as to recognition sites for acetylcholine.

Published
1989

43. Structure-activity relationships for steroid interaction with the gamma-aminobutyric acidA receptor complex.

Author

Harrison, N L, Majewska, M D, Harrington, J W, and Barker, J L

Abstract

Certain steroids are potent barbiturate-like modulators of the gamma-aminobutyric acidA (GABA) receptor-chloride ionophore complex in rat brain membranes. At nanomolar to low micromolar concentrations, these steroids stimulate [3H]flunitrazepam and [3H] muscimol binding and displace the convulsant [35S]t-butylbicyclophosphorothionate from its binding site in an allosteric manner, in addition to enhancing Cl- conductance responses to GABA recorded in cultured rat hippocampal and spinal neurons. A stringent structure-activity relationship exists for these interactions of steroids with the GABAA receptor complex. Comparison of the structure-activity relationship data obtained in this study with those for steroid-induced general anesthesia strongly suggests that steroidal anesthesia may result from the interaction between steroids and the GABAA receptor. The essential features of the active structures are a 5 alpha or 5 beta-reduced pregnane skeleton with a hydroxyl at C3 in the alpha-position and a ketone group at C20. These features are all present in some naturally occurring steroids, including metabolites of deoxycorticosterone and progesterone, that show potent activity at the GABAA receptor complex. Two of the compounds investigated are known to be formed in vivo as reduced metabolites of endogenous steroid hormones: 5 alpha-pregnane-3 alpha -ol-20-one and 5 alpha-pregnane-3 alpha,21-diol-20-one, which are derived from progesterone and deoxycorticosterone, respectively. These two steroids produce a striking prolongation of GABA-mediated inhibitory postsynaptic currents recorded at synapses between rat hippocampal neurons in culture and could conceivably regulate GABA-mediated inhibition under some physiologic and pathologic conditions.

Published
1987

44. Steroid control of uterine motility via γ-aminobutyric acidAreceptors in the rabbit: a novel mechanism?

Author

Majewska, M. D. and Vaupel, D. B.

Abstract

γ-Aminobutyric acid (GABA) is a regulator of uterine motility. Stimulation of GABAAreceptors tonically inhibited contractions of rabbit uterine strips, while stimulation of GABABreceptors enhanced contractions. Steroids appeared to interact with GABAAreceptors to modulate uterine contractility: tetrahydroprogesterone (THP) inhibited while pregnenolone sulphate (PS) increased contractions. THP rapidly antagonized the stimulatory effect of PS, but progesterone inhibited the contractions after a delay, suggesting that the known 'silencing' actions of progesterone on the uterus could be mediated via the metabolite THP, which potentiates the inhibitory function of GABAAreceptors. This novel mechanisms may play a role in uterine function during pregnancy and parturition.Journal of Endocrinology(1991) 131,427–434

Published
1991
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