5,793 research outputs found
Hypomethylating Agents in Treatment of Myelodysplastic Syndrome
Thelkey to the successful treatment of myelodysplastic syndrome is the careful characterization and diagnosis of the disease, which includes clinical, cytogenetic, biological and molecular investigation of individual patients. Today therapeutic approaches to the treatment of such patients are differentiated and depend, first of all, on the subtype of the disease, age, general condition of the patients and the possibility of allogeneic hematopoietic cell transplantation. For young patients, the best option is transplantation, whereas in older patients, the standard of therapy is the use of hypomethylating agents (azacitidine, decitabine). These drugs promote hematologic improvement, elimination of transfusion dependence and prolongation of the duration of both general and leukemia free survival in elderly patients with concomitant pathology.Despite the fact that therapy with hypomethylating drugs is widely used and has good results, many respondents are losing their response within 1–2 years. Reasons for the development of resistance to this type of treatment are still unclear, and the insensitivity to drugs is associated with very poor prognosis in patients with all subtypes of myelodysplastic syndrome. Such data and the presence of numerous genetic and epigenetic mechanisms for the development of this pathology have prompted the use of combinations of drugs with different application points and are relevant in terms of research. In the literature review, the results of clinical studies on the use of hypomethylating agents in patients with MDS of low and high risk, as in monotherapy and combined schemes are presented.The nearest prospect of treatment of myelodysplastic syndrome is the creation of new treatment regimens based on a combination of drugs of different pathogenetic direction for the elimination of the dysplastic clone in order to achieve not only long-term remissions, but also lengthening the duration of overall survival, especially for patients with high risk myelodysplastic syndrome
A simulation of the cluster structures in Ge-Se vitreous chalcogenide semiconductors
A structure of germanium selenide glasses is simulated by the featured
clusters built from the tetrahedral GeSe4 units up to the clusters with six
germanium atoms (Ge6Se16H4 and Ge6Se16H8). Quantum chemical calculations at the
DFT level with effective core potentials for Ge and Se atoms for the clusters
of different composition reveal their relative stability and optical
properties.Comment: 5 pages, 3 Figures include
Optimization of quantum cascade laser operation by geometric design of cascade active band in open and closed models
Using the effective mass and rectangular potential approximations, the theory
of electron dynamic conductivity is developed for the plane multilayer
resonance tunnel structure placed into a constant electric field within the
model of open nanosystem, and oscillator forces of quantum transitions within
the model of closed nanosystem. For the experimentally produced quantum cascade
laser with four-barrier active band of separate cascade, it is proven that just
the theory of dynamic conductivity in the model of open cascade most adequately
describes the radiation of high frequency electromagnetic field while the
electrons transport through the resonance tunnel structure driven by a constant
electric field.Comment: 10 pages, 2 figure
Nematocidial activity of aqueous solutions of plants of the families Cupressaceae, Rosaceae, Asteraceae, Fabaceae, Cannabaceae and Apiaceae
In natural ecosystems of animals, introduction of larvae of parasitic nematodes into the litter layer from excrement facilitates their migration and search of new host vertebrate animals. In such conditions they are constantly affected by biologically active substances of the abundant species of plants which grow in pastures. Currently, the influence of substances present in the above-ground part of plants on the vitality of larvae of helminths in the environment remains unstudied. In this article, we present the results of our research on the nematocidial activity in vitro in the aqueous solutions of 21 species of plants distributed in the territory of Steppe Ukraine: Sanguisorba officinalis L., Rosa canina L., Crataegus sanguinea Pall., Crataegus pentagyna Waldst. & Kit. ex Willd., Armeniaca vulgaris Lam., Taraxacum officinale F. H. Wigg., Iva xanthiifolia Nutt., Artemisia campestris L., Arctium minus (Hill) Bernh., Ambrosia artemisiifolia L., Cannabis sativa L., Humulus lupulus L., Melilotus officinalis (L.) Pall., Vicia cracca L., Lotus ucrainicus Klok., Onobrychis arenaria (Kit.) DC., Foeniculum vulgare Mill., Eryngium planum L., Conium maculatum L., Juniperus communis L., Thuja occidentalis L. The level of vitality of nematode larvae of the Strongylida (Haemonchus contortus (Rudolphi, 1803)) and Rhabditida (Strongyloides papillosus (Wedl, 1856)) orders varied depending on the species of plant, and also five experimental concentrations in aqueous solutions tested in seven replications. The most notable nematocidial effect was exerted by Taraxacum officinale F. H. Wigg. – we observed death of larvae of third stage development L3 H. contortus and larvae of first-third stages L1–3 S. papillosus at 24 h exposure to 3% aqueous solution. Three percent aqueous solutions of S. officinalis and A. artemisiifolia displayed nematocidial properties only against S. papillosus: death of L1–3 S. papillosus was observed. Aqueous solutions of R. canina, A. vulgaris, A. minus, H. lupulus, V. cracca, L. ucrainicus, O. arenaria, E. planum, C. maculatum, J. communis, Th. occidentalis had lethal effect only on non-invasive larvae (larvae of the first and second stage L1–2) of S. papillosus. They displayed no nematocidial properties towards invasive larvae of H. contortus and S. papillosus. At exposure to aqueous solutions of the rest of the studied species of plants, over 50% of L3 H. contortus and L1–3 S. papillosus larvae remained alive. The determined patterns allow us to state that while living in the litter and soil in the root zone of plants nematode larvae undergoa negative influence caused by some plant species
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