Search results for "Concentration."
showing 10 items of 1849 documents
Interactions of the alternating double stranded copolymer poly(dA-dT).poly(dA-dT) with NiCl2 and CdCl2: solution behaviour
2007
The thermal denaturation of the synthetic high molecular weight double stranded polynucleotide poly(dA-dT) x poly(dA-dT) has been studied in aqueous buffered solution (Tris 1.0 mM; pH 7.8+/-0.2) in the presence of increasing concentrations of either Ni(2+) (borderline cation) or Cd(2+) (soft cation) at four different constant ionic strength values (NaCl), making use of UV and circular dichroism (CD) spectroscopies. The experimental results show that the B-type double helix of the polymer is stabilized against thermal denaturation in the presence of both cations at low concentrations, relative to the systems where only NaCl is present, in the same conditions of ionic strength and pH. The eff…
Donnan equilibrium of ionic drugs in pH-dependent fixed charge membranes: theoretical modeling.
2002
Abstract We have studied theoretically the partition equilibrium of a cationic drug between an electrolyte solution and a membrane with pH-dependent fixed charges using an extended Donnan formalism. The aqueous solution within the fixed charge membrane is assumed to be in equilibrium with an external aqueous solution containing six ionic species: the cationic drug (DH + ), the salt cations (Na + and Ca 2+ ), the salt anion (Cl − ), and the hydrogen and hydroxide ions. In addition to these mobile species, the membrane solution may also contain four fixed species attached to the membrane chains: strongly acid sulfonic groups (SO 3 − ), weakly acid carboxylic groups in dissociated (COO − ) a…
Lead(II) ions adsorption onto amyloid particulates: An in depth study
2022
The production of new cost-effective biocompatible sorbent sustainable materials, with natural origins, able to remove heavy metals from water resources is nowadays highly desirable in order to reduce pollution and increase clean water availability. In this context, self-assembled protein materials with amyloid structures seem to have a great potential as natural platform for a broader development of highly-tunable structures. In this work we show how protein particulates, a generic form of protein aggregates, with spherical micro sized shape can be used as adsorbents of Pb2+ ions from aqueous solution. The effect of pH, ionic medium, ionic strength and temperature of the metal ion solution…
Artemisinin derivatives induce iron-dependent cell death (ferroptosis) in tumor cells
2015
Abstract Background Apoptosis and other forms of cell death have been intensively investigated in the past years to explain the mode of action of synthetic anticancer drugs and natural products. Recently, a new form of cell death emerged, which was termed ferroptosis, because it depends on intracellular iron. Here, the role of genes involved in iron metabolism and homeostasis for the cytotoxicity of ten artemisinin derivatives have been systematically investigated. Material and methods Log10IC50 values of 10 artemisinin derivatives (artesunate, artemether, arteether, artenimol, artemisitene, arteanuin B, another monomeric artemisinin derivative and three artemisinin dimer molecules) were co…
The oxidation of ubiquinol by the isolated rieske iron-sulfur protein in solution
1990
The pre-steady-state redox reactions of the Rieske iron-sulfur protein isolated from beef heart mitochondria have been characterized. The rates of oxidation by c-type cytochromes is much faster than the rate of reduction by ubiquinols. This enables the monitoring of the oxidation of ubiquinols by the Rieske protein through the steady-state electron transfer to cytochrome c in solution. The pH and ionic strength dependence of this reaction indicate that the ubiquinol anion is the direct reductant of the oxidized cluster of the iron-sulfur protein. The second electron from ubiquinol is diverted to oxygen by the isolated Rieske protein, and forms oxygen radicals that contribute to the steady-s…
Metabolic profiling of ripe olive fruit in response to moderate water stress
2013
a b s t r a c t The concentrations of different metabolites in olive (Olea europaea (L.)) fruit at harvest can be affected by water availability, with significant consequences on the composition and the quality of the resulting oil. The aim of the present study was to profile the metabolic composition of ripe olives (cv. Cipressino) grown under water-stress and irrigated conditions applied during the last part of the fruit developmental cycle (from pit hardening to commercial harvest). The imposed conditions resulted in a moderate water stress (−3.5 MPa) at the end of the experimental period. Samples (pulp + skin) of fruit collected at the stage of complete epicarp pigmentation were analyze…
The Jewish doctors involved in the development of health resorts in eastern Galicia at the late 19th and early 20th century (Central and Eastern Euro…
2018
Summary Background The involvement of Jewish doctors and scientists in the development of health resorts in eastern Galicia (part of the Austrian monarchy after 1772, and since 1918 as part of independent Poland, now part of Ukraine) is unquestionable; however, awareness of this fact is not that common. Meanwhile, also due to their work and activity, small borderland resorts became important medical, cultural and social centers of the region. The involvement of Jewish doctors in the development of Galician health resorts resulted from, among others, the rich and multi-layered tradition and integration of Judaism with the hygiene regulations and moral principles of the religion. The eastern …
Potential Antipsoriatic Avarol Derivatives as Antioxidants and Inhibitors of PGE2 Generation and Proliferation in the HaCaT Cell Line
2004
The synthesis and structure-activity relationships for a series of 14 new avarol derivatives as antioxidants and inhibitors of cell proliferation and PGE(2) generation in human keratinocytes are described. Compound 6 (thiosalicylic derivative) was the most potent inhibitor of superoxide generation in human neutrophils and also potently inhibited PGE(2) generation in the human keratinocyte HaCaT cell line. Compound 7(3'-methylaminoavarone) presented the best antiproliferative profile, by the inhibition of (3)H-thymidine incorporation in HaCaT cells, with potency similar to the reference compound anthralin. None of the avarol derivatives showed any sign of cytotoxicity measured as LDH release…
Biomimetic Alginate/Gelatin Cross-Linked Hydrogels Supplemented with Polyphosphate for Wound Healing Applications
2020
In the present study, the fabrication of a biomimetic wound dressing that mimics the extracellular matrix, consisting of a hydrogel matrix composed of non-oxidized and periodate-oxidized marine alginate, was prepared to which gelatin was bound via Schiff base formation. Into this alginate/oxidized-alginate-gelatin hydrogel, polyP was stably but reversibly integrated by ionic cross-linking with Zn2+ ions. Thereby, a soft hybrid material is obtained, consisting of a more rigid alginate scaffold and porous structures formed by the oxidized-alginate-gelatin hydrogel with ionically cross-linked polyP. Two forms of the Zn-polyP-containing matrices were obtained based on the property of polyP to f…
Synthesis and biological evaluation of dehydroabietic acid derivatives.
2010
A series of C18-oxygenated derivatives of dehydroabietic acid were synthesized from commercial abietic acid and evaluated for their cytotoxic, antimycotic, and antiviral activities.